diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
deleted file mode 100644
index 288780793..000000000
--- a/.github/workflows/go.yml
+++ /dev/null
@@ -1,26 +0,0 @@
-name: Go
-
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
-
-jobs:
-
-  build:
-    name: Build
-    runs-on: ubuntu-latest
-    steps:
-
-    - name: Setup Go environment
-      uses: actions/setup-go@v2
-
-    - name: Check out code into the Go module directory
-      uses: actions/checkout@v2
-
-    - name: Test
-      run: go test -race -coverprofile=coverage.txt -covermode=atomic ./...
-
-    - name: Codecov
-      uses: codecov/codecov-action@v1
diff --git a/.gitignore b/.gitignore
index 5bd4b85eb..e43b0f988 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,16 +1 @@
-# Binaries for programs and plugins
-*.exe
-*.exe~
-*.dll
-*.so
-*.dylib
-
-# Test binary, build with `go test -c`
-*.test
-
-# Output of the go coverage tool, specifically when used with LiteIDE
-*.out
-
-Makefile
-
-/leetcode*
+.DS_Store
diff --git a/CNAME b/CNAME
new file mode 100644
index 000000000..135ff1398
--- /dev/null
+++ b/CNAME
@@ -0,0 +1 @@
+leetcode.awesee.cn
\ No newline at end of file
diff --git a/LICENSE b/LICENSE
deleted file mode 100644
index 4a2706eb7..000000000
--- a/LICENSE
+++ /dev/null
@@ -1,21 +0,0 @@
-MIT License
-
-Copyright (c) 2018 Shuo
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
diff --git a/README.md b/README.md
index 340a1f882..fedae2030 100644
--- a/README.md
+++ b/README.md
@@ -1,461 +1 @@
-<!--|This file generated by command(leetcode readme); DO NOT EDIT.         |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-# [LeetCode](https://awesee.github.io/leetcode)
-LeetCode Problems' Solutions
-[[力扣](https://awesee.github.io/categories/leetcode/) ∙ [话题分类](https://github.com/awesee/leetcode/blob/master/tag/README.md)]
-
-[![Go](https://github.com/awesee/leetcode/workflows/Go/badge.svg)](https://github.com/awesee/leetcode/actions)
-[![codecov](https://codecov.io/gh/awesee/leetcode/branch/master/graph/badge.svg)](https://codecov.io/gh/awesee/leetcode)
-[![Go Report Card](https://goreportcard.com/badge/github.com/awesee/leetcode)](https://goreportcard.com/report/github.com/awesee/leetcode)
-[![GitHub contributors](https://img.shields.io/github/contributors/awesee/leetcode.svg)](https://github.com/awesee/leetcode/graphs/contributors)
-[![license](https://img.shields.io/github/license/awesee/leetcode.svg)](https://github.com/awesee/leetcode/blob/master/LICENSE)
-[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fawesee%2Fleetcode.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fawesee%2Fleetcode?ref=badge_shield)
-[![Join the chat](https://badges.gitter.im/awesee/leetcode.svg)](https://gitter.im/awesee/leetcode?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-
-<table><thead>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#1">[1-50]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#51">[51-100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#101">[101-150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#151">[151-200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#201">[201-250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#251">[251-300]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#301">[301-350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#351">[351-400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#401">[401-450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#451">[451-500]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#501">[501-550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#551">[551-600]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#601">[601-650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#651">[651-700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#701">[701-750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#751">[751-800]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#801">[801-850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#851">[851-900]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#901">[901-950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#951">[951-1000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1001">[1001-1050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1051">[1051-1100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1101">[1101-1150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1151">[1151-1200]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1201">[1201-1250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1251">[1251-1300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1301">[1301-1350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1351">[1351-1400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1401">[1401-1450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1451">[1451-1500]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1501">[1501-1550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1551">[1551-1600]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1601">[1601-1650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1651">[1651-1700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1701">[1701-1750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1751">[1751-1800]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1850">[1801-1850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1900">[1851-1900]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1950">[1901-1950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2000">[1951-2000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2050">[2001-2050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2100">[2051-2100]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2150">[2101-2150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2200">[2151-2200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2250">[2201-2250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2300">[2251-2300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2350">[2301-2350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2400">[2351-2400]</a></th>
-</tr>
-</thead></table>
-
-| # | Title | Solution | Difficulty |
-| :-: | - | - | :-: |
-| <span id="2173">2173</span> | [Longest Winning Streak](https://leetcode.com/problems/longest-winning-streak) 🔒 | [MySQL](problems/longest-winning-streak) | Hard |
-| <span id="2172">2172</span> | [Maximum AND Sum of Array](https://leetcode.com/problems/maximum-and-sum-of-array "数组的最大与和") | [Go](problems/maximum-and-sum-of-array) | Hard |
-| <span id="2171">2171</span> | [Removing Minimum Number of Magic Beans](https://leetcode.com/problems/removing-minimum-number-of-magic-beans "拿出最少数目的魔法豆") | [Go](problems/removing-minimum-number-of-magic-beans) | Medium |
-| <span id="2170">2170</span> | [Minimum Operations to Make the Array Alternating](https://leetcode.com/problems/minimum-operations-to-make-the-array-alternating "使数组变成交替数组的最少操作数") | [Go](problems/minimum-operations-to-make-the-array-alternating) | Medium |
-| <span id="2169">2169</span> | [Count Operations to Obtain Zero](https://leetcode.com/problems/count-operations-to-obtain-zero "得到 0 的操作数") | [Go](problems/count-operations-to-obtain-zero) | Easy |
-| <span id="2168">2168</span> | [Unique Substrings With Equal Digit Frequency](https://leetcode.com/problems/unique-substrings-with-equal-digit-frequency) 🔒 | [Go](problems/unique-substrings-with-equal-digit-frequency) | Medium |
-| <span id="2167">2167</span> | [Minimum Time to Remove All Cars Containing Illegal Goods](https://leetcode.com/problems/minimum-time-to-remove-all-cars-containing-illegal-goods "移除所有载有违禁货物车厢所需的最少时间") | [Go](problems/minimum-time-to-remove-all-cars-containing-illegal-goods) | Hard |
-| <span id="2166">2166</span> | [Design Bitset](https://leetcode.com/problems/design-bitset "设计位集") | [Go](problems/design-bitset) | Medium |
-| <span id="2165">2165</span> | [Smallest Value of the Rearranged Number](https://leetcode.com/problems/smallest-value-of-the-rearranged-number "重排数字的最小值") | [Go](problems/smallest-value-of-the-rearranged-number) | Medium |
-| <span id="2164">2164</span> | [Sort Even and Odd Indices Independently](https://leetcode.com/problems/sort-even-and-odd-indices-independently "对奇偶下标分别排序") | [Go](problems/sort-even-and-odd-indices-independently) | Easy |
-| <span id="2163">2163</span> | [Minimum Difference in Sums After Removal of Elements](https://leetcode.com/problems/minimum-difference-in-sums-after-removal-of-elements "删除元素后和的最小差值") | [Go](problems/minimum-difference-in-sums-after-removal-of-elements) | Hard |
-| <span id="2162">2162</span> | [Minimum Cost to Set Cooking Time](https://leetcode.com/problems/minimum-cost-to-set-cooking-time "设置时间的最少代价") | [Go](problems/minimum-cost-to-set-cooking-time) | Medium |
-| <span id="2161">2161</span> | [Partition Array According to Given Pivot](https://leetcode.com/problems/partition-array-according-to-given-pivot "根据给定数字划分数组") | [Go](problems/partition-array-according-to-given-pivot) | Medium |
-| <span id="2160">2160</span> | [Minimum Sum of Four Digit Number After Splitting Digits](https://leetcode.com/problems/minimum-sum-of-four-digit-number-after-splitting-digits "拆分数位后四位数字的最小和") | [Go](problems/minimum-sum-of-four-digit-number-after-splitting-digits) | Easy |
-| <span id="2159">2159</span> | [Order Two Columns Independently](https://leetcode.com/problems/order-two-columns-independently) 🔒 | [MySQL](problems/order-two-columns-independently) | Medium |
-| <span id="2158">2158</span> | [Amount of New Area Painted Each Day](https://leetcode.com/problems/amount-of-new-area-painted-each-day) 🔒 | [Go](problems/amount-of-new-area-painted-each-day) | Hard |
-| <span id="2157">2157</span> | [Groups of Strings](https://leetcode.com/problems/groups-of-strings "字符串分组") | [Go](problems/groups-of-strings) | Hard |
-| <span id="2156">2156</span> | [Find Substring With Given Hash Value](https://leetcode.com/problems/find-substring-with-given-hash-value "查找给定哈希值的子串") | [Go](problems/find-substring-with-given-hash-value) | Hard |
-| <span id="2155">2155</span> | [All Divisions With the Highest Score of a Binary Array](https://leetcode.com/problems/all-divisions-with-the-highest-score-of-a-binary-array "分组得分最高的所有下标") | [Go](problems/all-divisions-with-the-highest-score-of-a-binary-array) | Medium |
-| <span id="2154">2154</span> | [Keep Multiplying Found Values by Two](https://leetcode.com/problems/keep-multiplying-found-values-by-two "将找到的值乘以 2") | [Go](problems/keep-multiplying-found-values-by-two) | Easy |
-| <span id="2153">2153</span> | [The Number of Passengers in Each Bus II](https://leetcode.com/problems/the-number-of-passengers-in-each-bus-ii) 🔒 | [MySQL](problems/the-number-of-passengers-in-each-bus-ii) | Hard |
-| <span id="2152">2152</span> | [Minimum Number of Lines to Cover Points](https://leetcode.com/problems/minimum-number-of-lines-to-cover-points) 🔒 | [Go](problems/minimum-number-of-lines-to-cover-points) | Medium |
-| <span id="2151">2151</span> | [Maximum Good People Based on Statements](https://leetcode.com/problems/maximum-good-people-based-on-statements "基于陈述统计最多好人数") | [Go](problems/maximum-good-people-based-on-statements) | Hard |
-| <span id="2150">2150</span> | [Find All Lonely Numbers in the Array](https://leetcode.com/problems/find-all-lonely-numbers-in-the-array "找出数组中的所有孤独数字") | [Go](problems/find-all-lonely-numbers-in-the-array) | Medium |
-| <span id="2149">2149</span> | [Rearrange Array Elements by Sign](https://leetcode.com/problems/rearrange-array-elements-by-sign "按符号重排数组") | [Go](problems/rearrange-array-elements-by-sign) | Medium |
-| <span id="2148">2148</span> | [Count Elements With Strictly Smaller and Greater Elements](https://leetcode.com/problems/count-elements-with-strictly-smaller-and-greater-elements "元素计数") | [Go](problems/count-elements-with-strictly-smaller-and-greater-elements) | Easy |
-| <span id="2147">2147</span> | [Number of Ways to Divide a Long Corridor](https://leetcode.com/problems/number-of-ways-to-divide-a-long-corridor "分隔长廊的方案数") | [Go](problems/number-of-ways-to-divide-a-long-corridor) | Hard |
-| <span id="2146">2146</span> | [K Highest Ranked Items Within a Price Range](https://leetcode.com/problems/k-highest-ranked-items-within-a-price-range "价格范围内最高排名的 K 样物品") | [Go](problems/k-highest-ranked-items-within-a-price-range) | Medium |
-| <span id="2145">2145</span> | [Count the Hidden Sequences](https://leetcode.com/problems/count-the-hidden-sequences "统计隐藏数组数目") | [Go](problems/count-the-hidden-sequences) | Medium |
-| <span id="2144">2144</span> | [Minimum Cost of Buying Candies With Discount](https://leetcode.com/problems/minimum-cost-of-buying-candies-with-discount "打折购买糖果的最小开销") | [Go](problems/minimum-cost-of-buying-candies-with-discount) | Easy |
-| <span id="2143">2143</span> | [Choose Numbers From Two Arrays in Range](https://leetcode.com/problems/choose-numbers-from-two-arrays-in-range) 🔒 | [Go](problems/choose-numbers-from-two-arrays-in-range) | Hard |
-| <span id="2142">2142</span> | [The Number of Passengers in Each Bus I](https://leetcode.com/problems/the-number-of-passengers-in-each-bus-i) 🔒 | [MySQL](problems/the-number-of-passengers-in-each-bus-i) | Medium |
-| <span id="2141">2141</span> | [Maximum Running Time of N Computers](https://leetcode.com/problems/maximum-running-time-of-n-computers "同时运行 N 台电脑的最长时间") | [Go](problems/maximum-running-time-of-n-computers) | Hard |
-| <span id="2140">2140</span> | [Solving Questions With Brainpower](https://leetcode.com/problems/solving-questions-with-brainpower "解决智力问题") | [Go](problems/solving-questions-with-brainpower) | Medium |
-| <span id="2139">2139</span> | [Minimum Moves to Reach Target Score](https://leetcode.com/problems/minimum-moves-to-reach-target-score "得到目标值的最少行动次数") | [Go](problems/minimum-moves-to-reach-target-score) | Medium |
-| <span id="2138">2138</span> | [Divide a String Into Groups of Size k](https://leetcode.com/problems/divide-a-string-into-groups-of-size-k "将字符串拆分为若干长度为 k 的组") | [Go](problems/divide-a-string-into-groups-of-size-k) | Easy |
-| <span id="2137">2137</span> | [Pour Water Between Buckets to Make Water Levels Equal](https://leetcode.com/problems/pour-water-between-buckets-to-make-water-levels-equal) 🔒 | [Go](problems/pour-water-between-buckets-to-make-water-levels-equal) | Medium |
-| <span id="2136">2136</span> | [Earliest Possible Day of Full Bloom](https://leetcode.com/problems/earliest-possible-day-of-full-bloom "全部开花的最早一天") | [Go](problems/earliest-possible-day-of-full-bloom) | Hard |
-| <span id="2135">2135</span> | [Count Words Obtained After Adding a Letter](https://leetcode.com/problems/count-words-obtained-after-adding-a-letter "统计追加字母可以获得的单词数") | [Go](problems/count-words-obtained-after-adding-a-letter) | Medium |
-| <span id="2134">2134</span> | [Minimum Swaps to Group All 1's Together II](https://leetcode.com/problems/minimum-swaps-to-group-all-1s-together-ii "最少交换次数来组合所有的 1 II") | [Go](problems/minimum-swaps-to-group-all-1s-together-ii) | Medium |
-| <span id="2133">2133</span> | [Check if Every Row and Column Contains All Numbers](https://leetcode.com/problems/check-if-every-row-and-column-contains-all-numbers "检查是否每一行每一列都包含全部整数") | [Go](problems/check-if-every-row-and-column-contains-all-numbers) | Easy |
-| <span id="2132">2132</span> | [Stamping the Grid](https://leetcode.com/problems/stamping-the-grid "用邮票贴满网格图") | [Go](problems/stamping-the-grid) | Hard |
-| <span id="2131">2131</span> | [Longest Palindrome by Concatenating Two Letter Words](https://leetcode.com/problems/longest-palindrome-by-concatenating-two-letter-words "连接两字母单词得到的最长回文串") | [Go](problems/longest-palindrome-by-concatenating-two-letter-words) | Medium |
-| <span id="2130">2130</span> | [Maximum Twin Sum of a Linked List](https://leetcode.com/problems/maximum-twin-sum-of-a-linked-list "链表最大孪生和") | [Go](problems/maximum-twin-sum-of-a-linked-list) | Medium |
-| <span id="2129">2129</span> | [Capitalize the Title](https://leetcode.com/problems/capitalize-the-title "将标题首字母大写") | [Go](problems/capitalize-the-title) | Easy |
-| <span id="2128">2128</span> | [Remove All Ones With Row and Column Flips](https://leetcode.com/problems/remove-all-ones-with-row-and-column-flips) 🔒 | [Go](problems/remove-all-ones-with-row-and-column-flips) | Medium |
-| <span id="2127">2127</span> | [Maximum Employees to Be Invited to a Meeting](https://leetcode.com/problems/maximum-employees-to-be-invited-to-a-meeting "参加会议的最多员工数") | [Go](problems/maximum-employees-to-be-invited-to-a-meeting) | Hard |
-| <span id="2126">2126</span> | [Destroying Asteroids](https://leetcode.com/problems/destroying-asteroids "摧毁小行星") | [Go](problems/destroying-asteroids) | Medium |
-| <span id="2125">2125</span> | [Number of Laser Beams in a Bank](https://leetcode.com/problems/number-of-laser-beams-in-a-bank "银行中的激光束数量") | [Go](problems/number-of-laser-beams-in-a-bank) | Medium |
-| <span id="2124">2124</span> | [Check if All A's Appears Before All B's](https://leetcode.com/problems/check-if-all-as-appears-before-all-bs "检查是否所有 A 都在 B 之前") | [Go](problems/check-if-all-as-appears-before-all-bs) | Easy |
-| <span id="2123">2123</span> | [Minimum Operations to Remove Adjacent Ones in Matrix](https://leetcode.com/problems/minimum-operations-to-remove-adjacent-ones-in-matrix) 🔒 | [Go](problems/minimum-operations-to-remove-adjacent-ones-in-matrix) | Hard |
-| <span id="2122">2122</span> | [Recover the Original Array](https://leetcode.com/problems/recover-the-original-array "还原原数组") | [Go](problems/recover-the-original-array) | Hard |
-| <span id="2121">2121</span> | [Intervals Between Identical Elements](https://leetcode.com/problems/intervals-between-identical-elements "相同元素的间隔之和") | [Go](problems/intervals-between-identical-elements) | Medium |
-| <span id="2120">2120</span> | [Execution of All Suffix Instructions Staying in a Grid](https://leetcode.com/problems/execution-of-all-suffix-instructions-staying-in-a-grid "执行所有后缀指令") | [Go](problems/execution-of-all-suffix-instructions-staying-in-a-grid) | Medium |
-| <span id="2119">2119</span> | [A Number After a Double Reversal](https://leetcode.com/problems/a-number-after-a-double-reversal "反转两次的数字") | [Go](problems/a-number-after-a-double-reversal) | Easy |
-| <span id="2118">2118</span> | [Build the Equation](https://leetcode.com/problems/build-the-equation) 🔒 | [MySQL](problems/build-the-equation) | Hard |
-| <span id="2117">2117</span> | [Abbreviating the Product of a Range](https://leetcode.com/problems/abbreviating-the-product-of-a-range "一个区间内所有数乘积的缩写") | [Go](problems/abbreviating-the-product-of-a-range) | Hard |
-| <span id="2116">2116</span> | [Check if a Parentheses String Can Be Valid](https://leetcode.com/problems/check-if-a-parentheses-string-can-be-valid "判断一个括号字符串是否有效") | [Go](problems/check-if-a-parentheses-string-can-be-valid) | Medium |
-| <span id="2115">2115</span> | [Find All Possible Recipes from Given Supplies](https://leetcode.com/problems/find-all-possible-recipes-from-given-supplies "从给定原材料中找到所有可以做出的菜") | [Go](problems/find-all-possible-recipes-from-given-supplies) | Medium |
-| <span id="2114">2114</span> | [Maximum Number of Words Found in Sentences](https://leetcode.com/problems/maximum-number-of-words-found-in-sentences "句子中的最多单词数") | [Go](problems/maximum-number-of-words-found-in-sentences) | Easy |
-| <span id="2113">2113</span> | [Elements in Array After Removing and Replacing Elements](https://leetcode.com/problems/elements-in-array-after-removing-and-replacing-elements) 🔒 | [Go](problems/elements-in-array-after-removing-and-replacing-elements) | Medium |
-| <span id="2112">2112</span> | [The Airport With the Most Traffic](https://leetcode.com/problems/the-airport-with-the-most-traffic) 🔒 | [MySQL](problems/the-airport-with-the-most-traffic) | Medium |
-| <span id="2111">2111</span> | [Minimum Operations to Make the Array K-Increasing](https://leetcode.com/problems/minimum-operations-to-make-the-array-k-increasing "使数组 K 递增的最少操作次数") | [Go](problems/minimum-operations-to-make-the-array-k-increasing) | Hard |
-| <span id="2110">2110</span> | [Number of Smooth Descent Periods of a Stock](https://leetcode.com/problems/number-of-smooth-descent-periods-of-a-stock "股票平滑下跌阶段的数目") | [Go](problems/number-of-smooth-descent-periods-of-a-stock) | Medium |
-| <span id="2109">2109</span> | [Adding Spaces to a String](https://leetcode.com/problems/adding-spaces-to-a-string "向字符串添加空格") | [Go](problems/adding-spaces-to-a-string) | Medium |
-| <span id="2108">2108</span> | [Find First Palindromic String in the Array](https://leetcode.com/problems/find-first-palindromic-string-in-the-array "找出数组中的第一个回文字符串") | [Go](problems/find-first-palindromic-string-in-the-array) | Easy |
-| <span id="2107">2107</span> | [Number of Unique Flavors After Sharing K Candies](https://leetcode.com/problems/number-of-unique-flavors-after-sharing-k-candies) 🔒 | [Go](problems/number-of-unique-flavors-after-sharing-k-candies) | Medium |
-| <span id="2106">2106</span> | [Maximum Fruits Harvested After at Most K Steps](https://leetcode.com/problems/maximum-fruits-harvested-after-at-most-k-steps "摘水果") | [Go](problems/maximum-fruits-harvested-after-at-most-k-steps) | Hard |
-| <span id="2105">2105</span> | [Watering Plants II](https://leetcode.com/problems/watering-plants-ii "给植物浇水 II") | [Go](problems/watering-plants-ii) | Medium |
-| <span id="2104">2104</span> | [Sum of Subarray Ranges](https://leetcode.com/problems/sum-of-subarray-ranges "子数组范围和") | [Go](problems/sum-of-subarray-ranges) | Medium |
-| <span id="2103">2103</span> | [Rings and Rods](https://leetcode.com/problems/rings-and-rods "环和杆") | [Go](problems/rings-and-rods) | Easy |
-| <span id="2102">2102</span> | [Sequentially Ordinal Rank Tracker](https://leetcode.com/problems/sequentially-ordinal-rank-tracker "序列顺序查询") | [Go](problems/sequentially-ordinal-rank-tracker) | Hard |
-| <span id="2101">2101</span> | [Detonate the Maximum Bombs](https://leetcode.com/problems/detonate-the-maximum-bombs "引爆最多的炸弹") | [Go](problems/detonate-the-maximum-bombs) | Medium |
-| <span id="2100">2100</span> | [Find Good Days to Rob the Bank](https://leetcode.com/problems/find-good-days-to-rob-the-bank "适合打劫银行的日子") | [Go](problems/find-good-days-to-rob-the-bank) | Medium |
-| <span id="2099">2099</span> | [Find Subsequence of Length K With the Largest Sum](https://leetcode.com/problems/find-subsequence-of-length-k-with-the-largest-sum "找到和最大的长度为 K 的子序列") | [Go](problems/find-subsequence-of-length-k-with-the-largest-sum) | Easy |
-| <span id="2098">2098</span> | [Subsequence of Size K With the Largest Even Sum](https://leetcode.com/problems/subsequence-of-size-k-with-the-largest-even-sum) 🔒 | [Go](problems/subsequence-of-size-k-with-the-largest-even-sum) | Medium |
-| <span id="2097">2097</span> | [Valid Arrangement of Pairs](https://leetcode.com/problems/valid-arrangement-of-pairs "合法重新排列数对") | [Go](problems/valid-arrangement-of-pairs) | Hard |
-| <span id="2096">2096</span> | [Step-By-Step Directions From a Binary Tree Node to Another](https://leetcode.com/problems/step-by-step-directions-from-a-binary-tree-node-to-another "从二叉树一个节点到另一个节点每一步的方向") | [Go](problems/step-by-step-directions-from-a-binary-tree-node-to-another) | Medium |
-| <span id="2095">2095</span> | [Delete the Middle Node of a Linked List](https://leetcode.com/problems/delete-the-middle-node-of-a-linked-list "删除链表的中间节点") | [Go](problems/delete-the-middle-node-of-a-linked-list) | Medium |
-| <span id="2094">2094</span> | [Finding 3-Digit Even Numbers](https://leetcode.com/problems/finding-3-digit-even-numbers "找出 3 位偶数") | [Go](problems/finding-3-digit-even-numbers) | Easy |
-| <span id="2093">2093</span> | [Minimum Cost to Reach City With Discounts](https://leetcode.com/problems/minimum-cost-to-reach-city-with-discounts) 🔒 | [Go](problems/minimum-cost-to-reach-city-with-discounts) | Medium |
-| <span id="2092">2092</span> | [Find All People With Secret](https://leetcode.com/problems/find-all-people-with-secret "找出知晓秘密的所有专家") | [Go](problems/find-all-people-with-secret) | Hard |
-| <span id="2091">2091</span> | [Removing Minimum and Maximum From Array](https://leetcode.com/problems/removing-minimum-and-maximum-from-array "从数组中移除最大值和最小值") | [Go](problems/removing-minimum-and-maximum-from-array) | Medium |
-| <span id="2090">2090</span> | [K Radius Subarray Averages](https://leetcode.com/problems/k-radius-subarray-averages "半径为 k 的子数组平均值") | [Go](problems/k-radius-subarray-averages) | Medium |
-| <span id="2089">2089</span> | [Find Target Indices After Sorting Array](https://leetcode.com/problems/find-target-indices-after-sorting-array "找出数组排序后的目标下标") | [Go](problems/find-target-indices-after-sorting-array) | Easy |
-| <span id="2088">2088</span> | [Count Fertile Pyramids in a Land](https://leetcode.com/problems/count-fertile-pyramids-in-a-land "统计农场中肥沃金字塔的数目") | [Go](problems/count-fertile-pyramids-in-a-land) | Hard |
-| <span id="2087">2087</span> | [Minimum Cost Homecoming of a Robot in a Grid](https://leetcode.com/problems/minimum-cost-homecoming-of-a-robot-in-a-grid "网格图中机器人回家的最小代价") | [Go](problems/minimum-cost-homecoming-of-a-robot-in-a-grid) | Medium |
-| <span id="2086">2086</span> | [Minimum Number of Buckets Required to Collect Rainwater from Houses](https://leetcode.com/problems/minimum-number-of-buckets-required-to-collect-rainwater-from-houses "从房屋收集雨水需要的最少水桶数") | [Go](problems/minimum-number-of-buckets-required-to-collect-rainwater-from-houses) | Medium |
-| <span id="2085">2085</span> | [Count Common Words With One Occurrence](https://leetcode.com/problems/count-common-words-with-one-occurrence "统计出现过一次的公共字符串") | [Go](problems/count-common-words-with-one-occurrence) | Easy |
-| <span id="2084">2084</span> | [Drop Type 1 Orders for Customers With Type 0 Orders](https://leetcode.com/problems/drop-type-1-orders-for-customers-with-type-0-orders "为订单类型为 0 的客户删除类型为 1 的订单") 🔒 | [MySQL](problems/drop-type-1-orders-for-customers-with-type-0-orders) | Medium |
-| <span id="2083">2083</span> | [Substrings That Begin and End With the Same Letter](https://leetcode.com/problems/substrings-that-begin-and-end-with-the-same-letter "求以相同字母开头和结尾的子串总数") 🔒 | [Go](problems/substrings-that-begin-and-end-with-the-same-letter) | Medium |
-| <span id="2082">2082</span> | [The Number of Rich Customers](https://leetcode.com/problems/the-number-of-rich-customers "富有客户的数量") 🔒 | [MySQL](problems/the-number-of-rich-customers) | Easy |
-| <span id="2081">2081</span> | [Sum of k-Mirror Numbers](https://leetcode.com/problems/sum-of-k-mirror-numbers "k 镜像数字的和") | [Go](problems/sum-of-k-mirror-numbers) | Hard |
-| <span id="2080">2080</span> | [Range Frequency Queries](https://leetcode.com/problems/range-frequency-queries "区间内查询数字的频率") | [Go](problems/range-frequency-queries) | Medium |
-| <span id="2079">2079</span> | [Watering Plants](https://leetcode.com/problems/watering-plants "给植物浇水") | [Go](problems/watering-plants) | Medium |
-| <span id="2078">2078</span> | [Two Furthest Houses With Different Colors](https://leetcode.com/problems/two-furthest-houses-with-different-colors "两栋颜色不同且距离最远的房子") | [Go](problems/two-furthest-houses-with-different-colors) | Easy |
-| <span id="2077">2077</span> | [Paths in Maze That Lead to Same Room](https://leetcode.com/problems/paths-in-maze-that-lead-to-same-room) 🔒 | [Go](problems/paths-in-maze-that-lead-to-same-room) | Medium |
-| <span id="2076">2076</span> | [Process Restricted Friend Requests](https://leetcode.com/problems/process-restricted-friend-requests "处理含限制条件的好友请求") | [Go](problems/process-restricted-friend-requests) | Hard |
-| <span id="2075">2075</span> | [Decode the Slanted Ciphertext](https://leetcode.com/problems/decode-the-slanted-ciphertext "解码斜向换位密码") | [Go](problems/decode-the-slanted-ciphertext) | Medium |
-| <span id="2074">2074</span> | [Reverse Nodes in Even Length Groups](https://leetcode.com/problems/reverse-nodes-in-even-length-groups "反转偶数长度组的节点") | [Go](problems/reverse-nodes-in-even-length-groups) | Medium |
-| <span id="2073">2073</span> | [Time Needed to Buy Tickets](https://leetcode.com/problems/time-needed-to-buy-tickets "买票需要的时间") | [Go](problems/time-needed-to-buy-tickets) | Easy |
-| <span id="2072">2072</span> | [The Winner University](https://leetcode.com/problems/the-winner-university "赢得比赛的大学") 🔒 | [MySQL](problems/the-winner-university) | Easy |
-| <span id="2071">2071</span> | [Maximum Number of Tasks You Can Assign](https://leetcode.com/problems/maximum-number-of-tasks-you-can-assign "你可以安排的最多任务数目") | [Go](problems/maximum-number-of-tasks-you-can-assign) | Hard |
-| <span id="2070">2070</span> | [Most Beautiful Item for Each Query](https://leetcode.com/problems/most-beautiful-item-for-each-query "每一个查询的最大美丽值") | [Go](problems/most-beautiful-item-for-each-query) | Medium |
-| <span id="2069">2069</span> | [Walking Robot Simulation II](https://leetcode.com/problems/walking-robot-simulation-ii "模拟行走机器人 II") | [Go](problems/walking-robot-simulation-ii) | Medium |
-| <span id="2068">2068</span> | [Check Whether Two Strings are Almost Equivalent](https://leetcode.com/problems/check-whether-two-strings-are-almost-equivalent "检查两个字符串是否几乎相等") | [Go](problems/check-whether-two-strings-are-almost-equivalent) | Easy |
-| <span id="2067">2067</span> | [Number of Equal Count Substrings](https://leetcode.com/problems/number-of-equal-count-substrings) 🔒 | [Go](problems/number-of-equal-count-substrings) | Medium |
-| <span id="2066">2066</span> | [Account Balance](https://leetcode.com/problems/account-balance "账户余额") 🔒 | [MySQL](problems/account-balance) | Medium |
-| <span id="2065">2065</span> | [Maximum Path Quality of a Graph](https://leetcode.com/problems/maximum-path-quality-of-a-graph "最大化一张图中的路径价值") | [Go](problems/maximum-path-quality-of-a-graph) | Hard |
-| <span id="2064">2064</span> | [Minimized Maximum of Products Distributed to Any Store](https://leetcode.com/problems/minimized-maximum-of-products-distributed-to-any-store "分配给商店的最多商品的最小值") | [Go](problems/minimized-maximum-of-products-distributed-to-any-store) | Medium |
-| <span id="2063">2063</span> | [Vowels of All Substrings](https://leetcode.com/problems/vowels-of-all-substrings "所有子字符串中的元音") | [Go](problems/vowels-of-all-substrings) | Medium |
-| <span id="2062">2062</span> | [Count Vowel Substrings of a String](https://leetcode.com/problems/count-vowel-substrings-of-a-string "统计字符串中的元音子字符串") | [Go](problems/count-vowel-substrings-of-a-string) | Easy |
-| <span id="2061">2061</span> | [Number of Spaces Cleaning Robot Cleaned](https://leetcode.com/problems/number-of-spaces-cleaning-robot-cleaned "扫地机器人清扫过的空间个数") 🔒 | [Go](problems/number-of-spaces-cleaning-robot-cleaned) | Medium |
-| <span id="2060">2060</span> | [Check if an Original String Exists Given Two Encoded Strings](https://leetcode.com/problems/check-if-an-original-string-exists-given-two-encoded-strings "同源字符串检测") | [Go](problems/check-if-an-original-string-exists-given-two-encoded-strings) | Hard |
-| <span id="2059">2059</span> | [Minimum Operations to Convert Number](https://leetcode.com/problems/minimum-operations-to-convert-number "转化数字的最小运算数") | [Go](problems/minimum-operations-to-convert-number) | Medium |
-| <span id="2058">2058</span> | [Find the Minimum and Maximum Number of Nodes Between Critical Points](https://leetcode.com/problems/find-the-minimum-and-maximum-number-of-nodes-between-critical-points "找出临界点之间的最小和最大距离") | [Go](problems/find-the-minimum-and-maximum-number-of-nodes-between-critical-points) | Medium |
-| <span id="2057">2057</span> | [Smallest Index With Equal Value](https://leetcode.com/problems/smallest-index-with-equal-value "值相等的最小索引") | [Go](problems/smallest-index-with-equal-value) | Easy |
-| <span id="2056">2056</span> | [Number of Valid Move Combinations On Chessboard](https://leetcode.com/problems/number-of-valid-move-combinations-on-chessboard "棋盘上有效移动组合的数目") | [Go](problems/number-of-valid-move-combinations-on-chessboard) | Hard |
-| <span id="2055">2055</span> | [Plates Between Candles](https://leetcode.com/problems/plates-between-candles "蜡烛之间的盘子") | [Go](problems/plates-between-candles) | Medium |
-| <span id="2054">2054</span> | [Two Best Non-Overlapping Events](https://leetcode.com/problems/two-best-non-overlapping-events "两个最好的不重叠活动") | [Go](problems/two-best-non-overlapping-events) | Medium |
-| <span id="2053">2053</span> | [Kth Distinct String in an Array](https://leetcode.com/problems/kth-distinct-string-in-an-array "数组中第 K 个独一无二的字符串") | [Go](problems/kth-distinct-string-in-an-array) | Easy |
-| <span id="2052">2052</span> | [Minimum Cost to Separate Sentence Into Rows](https://leetcode.com/problems/minimum-cost-to-separate-sentence-into-rows "将句子分隔成行的最低成本") 🔒 | [Go](problems/minimum-cost-to-separate-sentence-into-rows) | Medium |
-| <span id="2051">2051</span> | [The Category of Each Member in the Store](https://leetcode.com/problems/the-category-of-each-member-in-the-store) 🔒 | [MySQL](problems/the-category-of-each-member-in-the-store) | Medium |
-| <span id="2050">2050</span> | [Parallel Courses III](https://leetcode.com/problems/parallel-courses-iii "并行课程 III") | [Go](problems/parallel-courses-iii) | Hard |
-| <span id="2049">2049</span> | [Count Nodes With the Highest Score](https://leetcode.com/problems/count-nodes-with-the-highest-score "统计最高分的节点数目") | [Go](problems/count-nodes-with-the-highest-score) | Medium |
-| <span id="2048">2048</span> | [Next Greater Numerically Balanced Number](https://leetcode.com/problems/next-greater-numerically-balanced-number "下一个更大的数值平衡数") | [Go](problems/next-greater-numerically-balanced-number) | Medium |
-| <span id="2047">2047</span> | [Number of Valid Words in a Sentence](https://leetcode.com/problems/number-of-valid-words-in-a-sentence "句子中的有效单词数") | [Go](problems/number-of-valid-words-in-a-sentence) | Easy |
-| <span id="2046">2046</span> | [Sort Linked List Already Sorted Using Absolute Values](https://leetcode.com/problems/sort-linked-list-already-sorted-using-absolute-values "给按照绝对值排序的链表排序") 🔒 | [Go](problems/sort-linked-list-already-sorted-using-absolute-values) | Medium |
-| <span id="2045">2045</span> | [Second Minimum Time to Reach Destination](https://leetcode.com/problems/second-minimum-time-to-reach-destination "到达目的地的第二短时间") | [Go](problems/second-minimum-time-to-reach-destination) | Hard |
-| <span id="2044">2044</span> | [Count Number of Maximum Bitwise-OR Subsets](https://leetcode.com/problems/count-number-of-maximum-bitwise-or-subsets "统计按位或能得到最大值的子集数目") | [Go](problems/count-number-of-maximum-bitwise-or-subsets) | Medium |
-| <span id="2043">2043</span> | [Simple Bank System](https://leetcode.com/problems/simple-bank-system "简易银行系统") | [Go](problems/simple-bank-system) | Medium |
-| <span id="2042">2042</span> | [Check if Numbers Are Ascending in a Sentence](https://leetcode.com/problems/check-if-numbers-are-ascending-in-a-sentence "检查句子中的数字是否递增") | [Go](problems/check-if-numbers-are-ascending-in-a-sentence) | Easy |
-| <span id="2041">2041</span> | [Accepted Candidates From the Interviews](https://leetcode.com/problems/accepted-candidates-from-the-interviews "面试中被录取的候选人") 🔒 | [MySQL](problems/accepted-candidates-from-the-interviews) | Medium |
-| <span id="2040">2040</span> | [Kth Smallest Product of Two Sorted Arrays](https://leetcode.com/problems/kth-smallest-product-of-two-sorted-arrays "两个有序数组的第 K 小乘积") | [Go](problems/kth-smallest-product-of-two-sorted-arrays) | Hard |
-| <span id="2039">2039</span> | [The Time When the Network Becomes Idle](https://leetcode.com/problems/the-time-when-the-network-becomes-idle "网络空闲的时刻") | [Go](problems/the-time-when-the-network-becomes-idle) | Medium |
-| <span id="2038">2038</span> | [Remove Colored Pieces if Both Neighbors are the Same Color](https://leetcode.com/problems/remove-colored-pieces-if-both-neighbors-are-the-same-color "如果相邻两个颜色均相同则删除当前颜色") | [Go](problems/remove-colored-pieces-if-both-neighbors-are-the-same-color) | Medium |
-| <span id="2037">2037</span> | [Minimum Number of Moves to Seat Everyone](https://leetcode.com/problems/minimum-number-of-moves-to-seat-everyone "使每位学生都有座位的最少移动次数") | [Go](problems/minimum-number-of-moves-to-seat-everyone) | Easy |
-| <span id="2036">2036</span> | [Maximum Alternating Subarray Sum](https://leetcode.com/problems/maximum-alternating-subarray-sum "最大交替子数组和") 🔒 | [Go](problems/maximum-alternating-subarray-sum) | Medium |
-| <span id="2035">2035</span> | [Partition Array Into Two Arrays to Minimize Sum Difference](https://leetcode.com/problems/partition-array-into-two-arrays-to-minimize-sum-difference "将数组分成两个数组并最小化数组和的差") | [Go](problems/partition-array-into-two-arrays-to-minimize-sum-difference) | Hard |
-| <span id="2034">2034</span> | [Stock Price Fluctuation](https://leetcode.com/problems/stock-price-fluctuation "股票价格波动") | [Go](problems/stock-price-fluctuation) | Medium |
-| <span id="2033">2033</span> | [Minimum Operations to Make a Uni-Value Grid](https://leetcode.com/problems/minimum-operations-to-make-a-uni-value-grid "获取单值网格的最小操作数") | [Go](problems/minimum-operations-to-make-a-uni-value-grid) | Medium |
-| <span id="2032">2032</span> | [Two Out of Three](https://leetcode.com/problems/two-out-of-three "至少在两个数组中出现的值") | [Go](problems/two-out-of-three) | Easy |
-| <span id="2031">2031</span> | [Count Subarrays With More Ones Than Zeros](https://leetcode.com/problems/count-subarrays-with-more-ones-than-zeros "1 比 0 多的子数组个数") 🔒 | [Go](problems/count-subarrays-with-more-ones-than-zeros) | Medium |
-| <span id="2030">2030</span> | [Smallest K-Length Subsequence With Occurrences of a Letter](https://leetcode.com/problems/smallest-k-length-subsequence-with-occurrences-of-a-letter "含特定字母的最小子序列") | [Go](problems/smallest-k-length-subsequence-with-occurrences-of-a-letter) | Hard |
-| <span id="2029">2029</span> | [Stone Game IX](https://leetcode.com/problems/stone-game-ix "石子游戏 IX") | [Go](problems/stone-game-ix) | Medium |
-| <span id="2028">2028</span> | [Find Missing Observations](https://leetcode.com/problems/find-missing-observations "找出缺失的观测数据") | [Go](problems/find-missing-observations) | Medium |
-| <span id="2027">2027</span> | [Minimum Moves to Convert String](https://leetcode.com/problems/minimum-moves-to-convert-string "转换字符串的最少操作次数") | [Go](problems/minimum-moves-to-convert-string) | Easy |
-| <span id="2026">2026</span> | [Low-Quality Problems](https://leetcode.com/problems/low-quality-problems "低质量的问题") 🔒 | [MySQL](problems/low-quality-problems) | Easy |
-| <span id="2025">2025</span> | [Maximum Number of Ways to Partition an Array](https://leetcode.com/problems/maximum-number-of-ways-to-partition-an-array "分割数组的最多方案数") | [Go](problems/maximum-number-of-ways-to-partition-an-array) | Hard |
-| <span id="2024">2024</span> | [Maximize the Confusion of an Exam](https://leetcode.com/problems/maximize-the-confusion-of-an-exam "考试的最大困扰度") | [Go](problems/maximize-the-confusion-of-an-exam) | Medium |
-| <span id="2023">2023</span> | [Number of Pairs of Strings With Concatenation Equal to Target](https://leetcode.com/problems/number-of-pairs-of-strings-with-concatenation-equal-to-target "连接后等于目标字符串的字符串对") | [Go](problems/number-of-pairs-of-strings-with-concatenation-equal-to-target) | Medium |
-| <span id="2022">2022</span> | [Convert 1D Array Into 2D Array](https://leetcode.com/problems/convert-1d-array-into-2d-array "将一维数组转变成二维数组") | [Go](problems/convert-1d-array-into-2d-array) | Easy |
-| <span id="2021">2021</span> | [Brightest Position on Street](https://leetcode.com/problems/brightest-position-on-street "街上最亮的位置") 🔒 | [Go](problems/brightest-position-on-street) | Medium |
-| <span id="2020">2020</span> | [Number of Accounts That Did Not Stream](https://leetcode.com/problems/number-of-accounts-that-did-not-stream) 🔒 | [MySQL](problems/number-of-accounts-that-did-not-stream) | Medium |
-| <span id="2019">2019</span> | [The Score of Students Solving Math Expression](https://leetcode.com/problems/the-score-of-students-solving-math-expression "解出数学表达式的学生分数") | [Go](problems/the-score-of-students-solving-math-expression) | Hard |
-| <span id="2018">2018</span> | [Check if Word Can Be Placed In Crossword](https://leetcode.com/problems/check-if-word-can-be-placed-in-crossword "判断单词是否能放入填字游戏内") | [Go](problems/check-if-word-can-be-placed-in-crossword) | Medium |
-| <span id="2017">2017</span> | [Grid Game](https://leetcode.com/problems/grid-game "网格游戏") | [Go](problems/grid-game) | Medium |
-| <span id="2016">2016</span> | [Maximum Difference Between Increasing Elements](https://leetcode.com/problems/maximum-difference-between-increasing-elements "增量元素之间的最大差值") | [Go](problems/maximum-difference-between-increasing-elements) | Easy |
-| <span id="2015">2015</span> | [Average Height of Buildings in Each Segment](https://leetcode.com/problems/average-height-of-buildings-in-each-segment) 🔒 | [Go](problems/average-height-of-buildings-in-each-segment) | Medium |
-| <span id="2014">2014</span> | [Longest Subsequence Repeated k Times](https://leetcode.com/problems/longest-subsequence-repeated-k-times "重复 K 次的最长子序列") | [Go](problems/longest-subsequence-repeated-k-times) | Hard |
-| <span id="2013">2013</span> | [Detect Squares](https://leetcode.com/problems/detect-squares "检测正方形") | [Go](problems/detect-squares) | Medium |
-| <span id="2012">2012</span> | [Sum of Beauty in the Array](https://leetcode.com/problems/sum-of-beauty-in-the-array "数组美丽值求和") | [Go](problems/sum-of-beauty-in-the-array) | Medium |
-| <span id="2011">2011</span> | [Final Value of Variable After Performing Operations](https://leetcode.com/problems/final-value-of-variable-after-performing-operations "执行操作后的变量值") | [Go](problems/final-value-of-variable-after-performing-operations) | Easy |
-| <span id="2010">2010</span> | [The Number of Seniors and Juniors to Join the Company II](https://leetcode.com/problems/the-number-of-seniors-and-juniors-to-join-the-company-ii) 🔒 | [MySQL](problems/the-number-of-seniors-and-juniors-to-join-the-company-ii) | Hard |
-| <span id="2009">2009</span> | [Minimum Number of Operations to Make Array Continuous](https://leetcode.com/problems/minimum-number-of-operations-to-make-array-continuous "使数组连续的最少操作数") | [Go](problems/minimum-number-of-operations-to-make-array-continuous) | Hard |
-| <span id="2008">2008</span> | [Maximum Earnings From Taxi](https://leetcode.com/problems/maximum-earnings-from-taxi "出租车的最大盈利") | [Go](problems/maximum-earnings-from-taxi) | Medium |
-| <span id="2007">2007</span> | [Find Original Array From Doubled Array](https://leetcode.com/problems/find-original-array-from-doubled-array "从双倍数组中还原原数组") | [Go](problems/find-original-array-from-doubled-array) | Medium |
-| <span id="2006">2006</span> | [Count Number of Pairs With Absolute Difference K](https://leetcode.com/problems/count-number-of-pairs-with-absolute-difference-k "差的绝对值为 K 的数对数目") | [Go](problems/count-number-of-pairs-with-absolute-difference-k) | Easy |
-| <span id="2005">2005</span> | [Subtree Removal Game with Fibonacci Tree](https://leetcode.com/problems/subtree-removal-game-with-fibonacci-tree "斐波那契树的移除子树游戏") 🔒 | [Go](problems/subtree-removal-game-with-fibonacci-tree) | Hard |
-| <span id="2004">2004</span> | [The Number of Seniors and Juniors to Join the Company](https://leetcode.com/problems/the-number-of-seniors-and-juniors-to-join-the-company) 🔒 | [MySQL](problems/the-number-of-seniors-and-juniors-to-join-the-company) | Hard |
-| <span id="2003">2003</span> | [Smallest Missing Genetic Value in Each Subtree](https://leetcode.com/problems/smallest-missing-genetic-value-in-each-subtree "每棵子树内缺失的最小基因值") | [Go](problems/smallest-missing-genetic-value-in-each-subtree) | Hard |
-| <span id="2002">2002</span> | [Maximum Product of the Length of Two Palindromic Subsequences](https://leetcode.com/problems/maximum-product-of-the-length-of-two-palindromic-subsequences "两个回文子序列长度的最大乘积") | [Go](problems/maximum-product-of-the-length-of-two-palindromic-subsequences) | Medium |
-| <span id="2001">2001</span> | [Number of Pairs of Interchangeable Rectangles](https://leetcode.com/problems/number-of-pairs-of-interchangeable-rectangles "可互换矩形的组数") | [Go](problems/number-of-pairs-of-interchangeable-rectangles) | Medium |
-| <span id="2000">2000</span> | [Reverse Prefix of Word](https://leetcode.com/problems/reverse-prefix-of-word "反转单词前缀") | [Go](problems/reverse-prefix-of-word) | Easy |
-| <span id="1999">1999</span> | [Smallest Greater Multiple Made of Two Digits](https://leetcode.com/problems/smallest-greater-multiple-made-of-two-digits "最小的仅由两个数组成的倍数") 🔒 | [Go](problems/smallest-greater-multiple-made-of-two-digits) | Medium |
-| <span id="1998">1998</span> | [GCD Sort of an Array](https://leetcode.com/problems/gcd-sort-of-an-array "数组的最大公因数排序") | [Go](problems/gcd-sort-of-an-array) | Hard |
-| <span id="1997">1997</span> | [First Day Where You Have Been in All the Rooms](https://leetcode.com/problems/first-day-where-you-have-been-in-all-the-rooms "访问完所有房间的第一天") | [Go](problems/first-day-where-you-have-been-in-all-the-rooms) | Medium |
-| <span id="1996">1996</span> | [The Number of Weak Characters in the Game](https://leetcode.com/problems/the-number-of-weak-characters-in-the-game "游戏中弱角色的数量") | [Go](problems/the-number-of-weak-characters-in-the-game) | Medium |
-| <span id="1995">1995</span> | [Count Special Quadruplets](https://leetcode.com/problems/count-special-quadruplets "统计特殊四元组") | [Go](problems/count-special-quadruplets) | Easy |
-| <span id="1994">1994</span> | [The Number of Good Subsets](https://leetcode.com/problems/the-number-of-good-subsets "好子集的数目") | [Go](problems/the-number-of-good-subsets) | Hard |
-| <span id="1993">1993</span> | [Operations on Tree](https://leetcode.com/problems/operations-on-tree "树上的操作") | [Go](problems/operations-on-tree) | Medium |
-| <span id="1992">1992</span> | [Find All Groups of Farmland](https://leetcode.com/problems/find-all-groups-of-farmland "找到所有的农场组") | [Go](problems/find-all-groups-of-farmland) | Medium |
-| <span id="1991">1991</span> | [Find the Middle Index in Array](https://leetcode.com/problems/find-the-middle-index-in-array "找到数组的中间位置") | [Go](problems/find-the-middle-index-in-array) | Easy |
-| <span id="1990">1990</span> | [Count the Number of Experiments](https://leetcode.com/problems/count-the-number-of-experiments "统计实验的数量") 🔒 | [MySQL](problems/count-the-number-of-experiments) | Medium |
-| <span id="1989">1989</span> | [Maximum Number of People That Can Be Caught in Tag](https://leetcode.com/problems/maximum-number-of-people-that-can-be-caught-in-tag) 🔒 | [Go](problems/maximum-number-of-people-that-can-be-caught-in-tag) | Medium |
-| <span id="1988">1988</span> | [Find Cutoff Score for Each School](https://leetcode.com/problems/find-cutoff-score-for-each-school "找出每所学校的最低分数要求") 🔒 | [MySQL](problems/find-cutoff-score-for-each-school) | Medium |
-| <span id="1987">1987</span> | [Number of Unique Good Subsequences](https://leetcode.com/problems/number-of-unique-good-subsequences "不同的好子序列数目") | [Go](problems/number-of-unique-good-subsequences) | Hard |
-| <span id="1986">1986</span> | [Minimum Number of Work Sessions to Finish the Tasks](https://leetcode.com/problems/minimum-number-of-work-sessions-to-finish-the-tasks "完成任务的最少工作时间段") | [Go](problems/minimum-number-of-work-sessions-to-finish-the-tasks) | Medium |
-| <span id="1985">1985</span> | [Find the Kth Largest Integer in the Array](https://leetcode.com/problems/find-the-kth-largest-integer-in-the-array "找出数组中的第 K 大整数") | [Go](problems/find-the-kth-largest-integer-in-the-array) | Medium |
-| <span id="1984">1984</span> | [Minimum Difference Between Highest and Lowest of K Scores](https://leetcode.com/problems/minimum-difference-between-highest-and-lowest-of-k-scores "学生分数的最小差值") | [Go](problems/minimum-difference-between-highest-and-lowest-of-k-scores) | Easy |
-| <span id="1983">1983</span> | [Widest Pair of Indices With Equal Range Sum](https://leetcode.com/problems/widest-pair-of-indices-with-equal-range-sum) 🔒 | [Go](problems/widest-pair-of-indices-with-equal-range-sum) | Medium |
-| <span id="1982">1982</span> | [Find Array Given Subset Sums](https://leetcode.com/problems/find-array-given-subset-sums "从子集的和还原数组") | [Go](problems/find-array-given-subset-sums) | Hard |
-| <span id="1981">1981</span> | [Minimize the Difference Between Target and Chosen Elements](https://leetcode.com/problems/minimize-the-difference-between-target-and-chosen-elements "最小化目标值与所选元素的差") | [Go](problems/minimize-the-difference-between-target-and-chosen-elements) | Medium |
-| <span id="1980">1980</span> | [Find Unique Binary String](https://leetcode.com/problems/find-unique-binary-string "找出不同的二进制字符串") | [Go](problems/find-unique-binary-string) | Medium |
-| <span id="1979">1979</span> | [Find Greatest Common Divisor of Array](https://leetcode.com/problems/find-greatest-common-divisor-of-array "找出数组的最大公约数") | [Go](problems/find-greatest-common-divisor-of-array) | Easy |
-| <span id="1978">1978</span> | [Employees Whose Manager Left the Company](https://leetcode.com/problems/employees-whose-manager-left-the-company "上级经理已离职的公司员工") 🔒 | [MySQL](problems/employees-whose-manager-left-the-company) | Easy |
-| <span id="1977">1977</span> | [Number of Ways to Separate Numbers](https://leetcode.com/problems/number-of-ways-to-separate-numbers "划分数字的方案数") | [Go](problems/number-of-ways-to-separate-numbers) | Hard |
-| <span id="1976">1976</span> | [Number of Ways to Arrive at Destination](https://leetcode.com/problems/number-of-ways-to-arrive-at-destination "到达目的地的方案数") | [Go](problems/number-of-ways-to-arrive-at-destination) | Medium |
-| <span id="1975">1975</span> | [Maximum Matrix Sum](https://leetcode.com/problems/maximum-matrix-sum "最大方阵和") | [Go](problems/maximum-matrix-sum) | Medium |
-| <span id="1974">1974</span> | [Minimum Time to Type Word Using Special Typewriter](https://leetcode.com/problems/minimum-time-to-type-word-using-special-typewriter "使用特殊打字机键入单词的最少时间") | [Go](problems/minimum-time-to-type-word-using-special-typewriter) | Easy |
-| <span id="1973">1973</span> | [Count Nodes Equal to Sum of Descendants](https://leetcode.com/problems/count-nodes-equal-to-sum-of-descendants "值等于子节点值之和的节点数量") 🔒 | [Go](problems/count-nodes-equal-to-sum-of-descendants) | Medium |
-| <span id="1972">1972</span> | [First and Last Call On the Same Day](https://leetcode.com/problems/first-and-last-call-on-the-same-day "同一天的第一个电话和最后一个电话") 🔒 | [MySQL](problems/first-and-last-call-on-the-same-day) | Hard |
-| <span id="1971">1971</span> | [Find if Path Exists in Graph](https://leetcode.com/problems/find-if-path-exists-in-graph "寻找图中是否存在路径") | [Go](problems/find-if-path-exists-in-graph) | Easy |
-| <span id="1970">1970</span> | [Last Day Where You Can Still Cross](https://leetcode.com/problems/last-day-where-you-can-still-cross "你能穿过矩阵的最后一天") | [Go](problems/last-day-where-you-can-still-cross) | Hard |
-| <span id="1969">1969</span> | [Minimum Non-Zero Product of the Array Elements](https://leetcode.com/problems/minimum-non-zero-product-of-the-array-elements "数组元素的最小非零乘积") | [Go](problems/minimum-non-zero-product-of-the-array-elements) | Medium |
-| <span id="1968">1968</span> | [Array With Elements Not Equal to Average of Neighbors](https://leetcode.com/problems/array-with-elements-not-equal-to-average-of-neighbors "构造元素不等于两相邻元素平均值的数组") | [Go](problems/array-with-elements-not-equal-to-average-of-neighbors) | Medium |
-| <span id="1967">1967</span> | [Number of Strings That Appear as Substrings in Word](https://leetcode.com/problems/number-of-strings-that-appear-as-substrings-in-word "作为子字符串出现在单词中的字符串数目") | [Go](problems/number-of-strings-that-appear-as-substrings-in-word) | Easy |
-| <span id="1966">1966</span> | [Binary Searchable Numbers in an Unsorted Array](https://leetcode.com/problems/binary-searchable-numbers-in-an-unsorted-array "未排序数组中的可被二分搜索的数") 🔒 | [Go](problems/binary-searchable-numbers-in-an-unsorted-array) | Medium |
-| <span id="1965">1965</span> | [Employees With Missing Information](https://leetcode.com/problems/employees-with-missing-information "丢失信息的雇员") 🔒 | [MySQL](problems/employees-with-missing-information) | Easy |
-| <span id="1964">1964</span> | [Find the Longest Valid Obstacle Course at Each Position](https://leetcode.com/problems/find-the-longest-valid-obstacle-course-at-each-position "找出到每个位置为止最长的有效障碍赛跑路线") | [Go](problems/find-the-longest-valid-obstacle-course-at-each-position) | Hard |
-| <span id="1963">1963</span> | [Minimum Number of Swaps to Make the String Balanced](https://leetcode.com/problems/minimum-number-of-swaps-to-make-the-string-balanced "使字符串平衡的最小交换次数") | [Go](problems/minimum-number-of-swaps-to-make-the-string-balanced) | Medium |
-| <span id="1962">1962</span> | [Remove Stones to Minimize the Total](https://leetcode.com/problems/remove-stones-to-minimize-the-total "移除石子使总数最小") | [Go](problems/remove-stones-to-minimize-the-total) | Medium |
-| <span id="1961">1961</span> | [Check If String Is a Prefix of Array](https://leetcode.com/problems/check-if-string-is-a-prefix-of-array "检查字符串是否为数组前缀") | [Go](problems/check-if-string-is-a-prefix-of-array) | Easy |
-| <span id="1960">1960</span> | [Maximum Product of the Length of Two Palindromic Substrings](https://leetcode.com/problems/maximum-product-of-the-length-of-two-palindromic-substrings "两个回文子字符串长度的最大乘积") | [Go](problems/maximum-product-of-the-length-of-two-palindromic-substrings) | Hard |
-| <span id="1959">1959</span> | [Minimum Total Space Wasted With K Resizing Operations](https://leetcode.com/problems/minimum-total-space-wasted-with-k-resizing-operations "K 次调整数组大小浪费的最小总空间") | [Go](problems/minimum-total-space-wasted-with-k-resizing-operations) | Medium |
-| <span id="1958">1958</span> | [Check if Move is Legal](https://leetcode.com/problems/check-if-move-is-legal "检查操作是否合法") | [Go](problems/check-if-move-is-legal) | Medium |
-| <span id="1957">1957</span> | [Delete Characters to Make Fancy String](https://leetcode.com/problems/delete-characters-to-make-fancy-string "删除字符使字符串变好") | [Go](problems/delete-characters-to-make-fancy-string) | Easy |
-| <span id="1956">1956</span> | [Minimum Time For K Virus Variants to Spread](https://leetcode.com/problems/minimum-time-for-k-virus-variants-to-spread "感染 K 种病毒所需的最短时间") 🔒 | [Go](problems/minimum-time-for-k-virus-variants-to-spread) | Hard |
-| <span id="1955">1955</span> | [Count Number of Special Subsequences](https://leetcode.com/problems/count-number-of-special-subsequences "统计特殊子序列的数目") | [Go](problems/count-number-of-special-subsequences) | Hard |
-| <span id="1954">1954</span> | [Minimum Garden Perimeter to Collect Enough Apples](https://leetcode.com/problems/minimum-garden-perimeter-to-collect-enough-apples "收集足够苹果的最小花园周长") | [Go](problems/minimum-garden-perimeter-to-collect-enough-apples) | Medium |
-| <span id="1953">1953</span> | [Maximum Number of Weeks for Which You Can Work](https://leetcode.com/problems/maximum-number-of-weeks-for-which-you-can-work "你可以工作的最大周数") | [Go](problems/maximum-number-of-weeks-for-which-you-can-work) | Medium |
-| <span id="1952">1952</span> | [Three Divisors](https://leetcode.com/problems/three-divisors "三除数") | [Go](problems/three-divisors) | Easy |
-| <span id="1951">1951</span> | [All the Pairs With the Maximum Number of Common Followers](https://leetcode.com/problems/all-the-pairs-with-the-maximum-number-of-common-followers "查询具有最多共同关注者的所有两两结对组") 🔒 | [MySQL](problems/all-the-pairs-with-the-maximum-number-of-common-followers) | Medium |
-| <span id="1950">1950</span> | [Maximum of Minimum Values in All Subarrays](https://leetcode.com/problems/maximum-of-minimum-values-in-all-subarrays "所有子数组最小值中的最大值") 🔒 | [Go](problems/maximum-of-minimum-values-in-all-subarrays) | Medium |
-| <span id="1949">1949</span> | [Strong Friendship](https://leetcode.com/problems/strong-friendship "坚定的友谊") 🔒 | [MySQL](problems/strong-friendship) | Medium |
-| <span id="1948">1948</span> | [Delete Duplicate Folders in System](https://leetcode.com/problems/delete-duplicate-folders-in-system "删除系统中的重复文件夹") | [Go](problems/delete-duplicate-folders-in-system) | Hard |
-| <span id="1947">1947</span> | [Maximum Compatibility Score Sum](https://leetcode.com/problems/maximum-compatibility-score-sum "最大兼容性评分和") | [Go](problems/maximum-compatibility-score-sum) | Medium |
-| <span id="1946">1946</span> | [Largest Number After Mutating Substring](https://leetcode.com/problems/largest-number-after-mutating-substring "子字符串突变后可能得到的最大整数") | [Go](problems/largest-number-after-mutating-substring) | Medium |
-| <span id="1945">1945</span> | [Sum of Digits of String After Convert](https://leetcode.com/problems/sum-of-digits-of-string-after-convert "字符串转化后的各位数字之和") | [Go](problems/sum-of-digits-of-string-after-convert) | Easy |
-| <span id="1944">1944</span> | [Number of Visible People in a Queue](https://leetcode.com/problems/number-of-visible-people-in-a-queue "队列中可以看到的人数") | [Go](problems/number-of-visible-people-in-a-queue) | Hard |
-| <span id="1943">1943</span> | [Describe the Painting](https://leetcode.com/problems/describe-the-painting "描述绘画结果") | [Go](problems/describe-the-painting) | Medium |
-| <span id="1942">1942</span> | [The Number of the Smallest Unoccupied Chair](https://leetcode.com/problems/the-number-of-the-smallest-unoccupied-chair "最小未被占据椅子的编号") | [Go](problems/the-number-of-the-smallest-unoccupied-chair) | Medium |
-| <span id="1941">1941</span> | [Check if All Characters Have Equal Number of Occurrences](https://leetcode.com/problems/check-if-all-characters-have-equal-number-of-occurrences "检查是否所有字符出现次数相同") | [Go](problems/check-if-all-characters-have-equal-number-of-occurrences) | Easy |
-| <span id="1940">1940</span> | [Longest Common Subsequence Between Sorted Arrays](https://leetcode.com/problems/longest-common-subsequence-between-sorted-arrays "排序数组之间的最长公共子序列") 🔒 | [Go](problems/longest-common-subsequence-between-sorted-arrays) | Medium |
-| <span id="1939">1939</span> | [Users That Actively Request Confirmation Messages](https://leetcode.com/problems/users-that-actively-request-confirmation-messages "主动请求确认消息的用户") 🔒 | [MySQL](problems/users-that-actively-request-confirmation-messages) | Easy |
-| <span id="1938">1938</span> | [Maximum Genetic Difference Query](https://leetcode.com/problems/maximum-genetic-difference-query "查询最大基因差") | [Go](problems/maximum-genetic-difference-query) | Hard |
-| <span id="1937">1937</span> | [Maximum Number of Points with Cost](https://leetcode.com/problems/maximum-number-of-points-with-cost "扣分后的最大得分") | [Go](problems/maximum-number-of-points-with-cost) | Medium |
-| <span id="1936">1936</span> | [Add Minimum Number of Rungs](https://leetcode.com/problems/add-minimum-number-of-rungs "新增的最少台阶数") | [Go](problems/add-minimum-number-of-rungs) | Medium |
-| <span id="1935">1935</span> | [Maximum Number of Words You Can Type](https://leetcode.com/problems/maximum-number-of-words-you-can-type "可以输入的最大单词数") | [Go](problems/maximum-number-of-words-you-can-type) | Easy |
-| <span id="1934">1934</span> | [Confirmation Rate](https://leetcode.com/problems/confirmation-rate) 🔒 | [MySQL](problems/confirmation-rate) | Medium |
-| <span id="1933">1933</span> | [Check if String Is Decomposable Into Value-Equal Substrings](https://leetcode.com/problems/check-if-string-is-decomposable-into-value-equal-substrings "判断字符串是否可分解为值均等的子串") 🔒 | [Go](problems/check-if-string-is-decomposable-into-value-equal-substrings) | Easy |
-| <span id="1932">1932</span> | [Merge BSTs to Create Single BST](https://leetcode.com/problems/merge-bsts-to-create-single-bst "合并多棵二叉搜索树") | [Go](problems/merge-bsts-to-create-single-bst) | Hard |
-| <span id="1931">1931</span> | [Painting a Grid With Three Different Colors](https://leetcode.com/problems/painting-a-grid-with-three-different-colors "用三种不同颜色为网格涂色") | [Go](problems/painting-a-grid-with-three-different-colors) | Hard |
-| <span id="1930">1930</span> | [Unique Length-3 Palindromic Subsequences](https://leetcode.com/problems/unique-length-3-palindromic-subsequences "长度为 3 的不同回文子序列") | [Go](problems/unique-length-3-palindromic-subsequences) | Medium |
-| <span id="1929">1929</span> | [Concatenation of Array](https://leetcode.com/problems/concatenation-of-array "数组串联") | [Go](problems/concatenation-of-array) | Easy |
-| <span id="1928">1928</span> | [Minimum Cost to Reach Destination in Time](https://leetcode.com/problems/minimum-cost-to-reach-destination-in-time "规定时间内到达终点的最小花费") | [Go](problems/minimum-cost-to-reach-destination-in-time) | Hard |
-| <span id="1927">1927</span> | [Sum Game](https://leetcode.com/problems/sum-game "求和游戏") | [Go](problems/sum-game) | Medium |
-| <span id="1926">1926</span> | [Nearest Exit from Entrance in Maze](https://leetcode.com/problems/nearest-exit-from-entrance-in-maze "迷宫中离入口最近的出口") | [Go](problems/nearest-exit-from-entrance-in-maze) | Medium |
-| <span id="1925">1925</span> | [Count Square Sum Triples](https://leetcode.com/problems/count-square-sum-triples "统计平方和三元组的数目") | [Go](problems/count-square-sum-triples) | Easy |
-| <span id="1924">1924</span> | [Erect the Fence II](https://leetcode.com/problems/erect-the-fence-ii "安装栅栏 II") 🔒 | [Go](problems/erect-the-fence-ii) | Hard |
-| <span id="1923">1923</span> | [Longest Common Subpath](https://leetcode.com/problems/longest-common-subpath "最长公共子路径") | [Go](problems/longest-common-subpath) | Hard |
-| <span id="1922">1922</span> | [Count Good Numbers](https://leetcode.com/problems/count-good-numbers "统计好数字的数目") | [Go](problems/count-good-numbers) | Medium |
-| <span id="1921">1921</span> | [Eliminate Maximum Number of Monsters](https://leetcode.com/problems/eliminate-maximum-number-of-monsters "消灭怪物的最大数量") | [Go](problems/eliminate-maximum-number-of-monsters) | Medium |
-| <span id="1920">1920</span> | [Build Array from Permutation](https://leetcode.com/problems/build-array-from-permutation "基于排列构建数组") | [Go](problems/build-array-from-permutation) | Easy |
-| <span id="1919">1919</span> | [Leetcodify Similar Friends](https://leetcode.com/problems/leetcodify-similar-friends "兴趣相同的朋友") 🔒 | [MySQL](problems/leetcodify-similar-friends) | Hard |
-| <span id="1918">1918</span> | [Kth Smallest Subarray Sum](https://leetcode.com/problems/kth-smallest-subarray-sum "第 K 小的子数组和·") 🔒 | [Go](problems/kth-smallest-subarray-sum) | Medium |
-| <span id="1917">1917</span> | [Leetcodify Friends Recommendations](https://leetcode.com/problems/leetcodify-friends-recommendations "Leetcodify 好友推荐") 🔒 | [MySQL](problems/leetcodify-friends-recommendations) | Hard |
-| <span id="1916">1916</span> | [Count Ways to Build Rooms in an Ant Colony](https://leetcode.com/problems/count-ways-to-build-rooms-in-an-ant-colony "统计为蚁群构筑房间的不同顺序") | [Go](problems/count-ways-to-build-rooms-in-an-ant-colony) | Hard |
-| <span id="1915">1915</span> | [Number of Wonderful Substrings](https://leetcode.com/problems/number-of-wonderful-substrings "最美子字符串的数目") | [Go](problems/number-of-wonderful-substrings) | Medium |
-| <span id="1914">1914</span> | [Cyclically Rotating a Grid](https://leetcode.com/problems/cyclically-rotating-a-grid "循环轮转矩阵") | [Go](problems/cyclically-rotating-a-grid) | Medium |
-| <span id="1913">1913</span> | [Maximum Product Difference Between Two Pairs](https://leetcode.com/problems/maximum-product-difference-between-two-pairs "两个数对之间的最大乘积差") | [Go](problems/maximum-product-difference-between-two-pairs) | Easy |
-| <span id="1912">1912</span> | [Design Movie Rental System](https://leetcode.com/problems/design-movie-rental-system "设计电影租借系统") | [Go](problems/design-movie-rental-system) | Hard |
-| <span id="1911">1911</span> | [Maximum Alternating Subsequence Sum](https://leetcode.com/problems/maximum-alternating-subsequence-sum "最大子序列交替和") | [Go](problems/maximum-alternating-subsequence-sum) | Medium |
-| <span id="1910">1910</span> | [Remove All Occurrences of a Substring](https://leetcode.com/problems/remove-all-occurrences-of-a-substring "删除一个字符串中所有出现的给定子字符串") | [Go](problems/remove-all-occurrences-of-a-substring) | Medium |
-| <span id="1909">1909</span> | [Remove One Element to Make the Array Strictly Increasing](https://leetcode.com/problems/remove-one-element-to-make-the-array-strictly-increasing "删除一个元素使数组严格递增") | [Go](problems/remove-one-element-to-make-the-array-strictly-increasing) | Easy |
-| <span id="1908">1908</span> | [Game of Nim](https://leetcode.com/problems/game-of-nim "Nim 游戏 II") 🔒 | [Go](problems/game-of-nim) | Medium |
-| <span id="1907">1907</span> | [Count Salary Categories](https://leetcode.com/problems/count-salary-categories "按分类统计薪水") 🔒 | [MySQL](problems/count-salary-categories) | Medium |
-| <span id="1906">1906</span> | [Minimum Absolute Difference Queries](https://leetcode.com/problems/minimum-absolute-difference-queries "查询差绝对值的最小值") | [Go](problems/minimum-absolute-difference-queries) | Medium |
-| <span id="1905">1905</span> | [Count Sub Islands](https://leetcode.com/problems/count-sub-islands "统计子岛屿") | [Go](problems/count-sub-islands) | Medium |
-| <span id="1904">1904</span> | [The Number of Full Rounds You Have Played](https://leetcode.com/problems/the-number-of-full-rounds-you-have-played "你完成的完整对局数") | [Go](problems/the-number-of-full-rounds-you-have-played) | Medium |
-| <span id="1903">1903</span> | [Largest Odd Number in String](https://leetcode.com/problems/largest-odd-number-in-string "字符串中的最大奇数") | [Go](problems/largest-odd-number-in-string) | Easy |
-| <span id="1902">1902</span> | [Depth of BST Given Insertion Order](https://leetcode.com/problems/depth-of-bst-given-insertion-order "给定二叉搜索树的插入顺序求深度") 🔒 | [Go](problems/depth-of-bst-given-insertion-order) | Medium |
-| <span id="1901">1901</span> | [Find a Peak Element II](https://leetcode.com/problems/find-a-peak-element-ii "找出顶峰元素 II") | [Go](problems/find-a-peak-element-ii) | Medium |
-| <span id="1900">1900</span> | [The Earliest and Latest Rounds Where Players Compete](https://leetcode.com/problems/the-earliest-and-latest-rounds-where-players-compete "最佳运动员的比拼回合") | [Go](problems/the-earliest-and-latest-rounds-where-players-compete) | Hard |
-| <span id="1899">1899</span> | [Merge Triplets to Form Target Triplet](https://leetcode.com/problems/merge-triplets-to-form-target-triplet "合并若干三元组以形成目标三元组") | [Go](problems/merge-triplets-to-form-target-triplet) | Medium |
-| <span id="1898">1898</span> | [Maximum Number of Removable Characters](https://leetcode.com/problems/maximum-number-of-removable-characters "可移除字符的最大数目") | [Go](problems/maximum-number-of-removable-characters) | Medium |
-| <span id="1897">1897</span> | [Redistribute Characters to Make All Strings Equal](https://leetcode.com/problems/redistribute-characters-to-make-all-strings-equal "重新分配字符使所有字符串都相等") | [Go](problems/redistribute-characters-to-make-all-strings-equal) | Easy |
-| <span id="1896">1896</span> | [Minimum Cost to Change the Final Value of Expression](https://leetcode.com/problems/minimum-cost-to-change-the-final-value-of-expression "反转表达式值的最少操作次数") | [Go](problems/minimum-cost-to-change-the-final-value-of-expression) | Hard |
-| <span id="1895">1895</span> | [Largest Magic Square](https://leetcode.com/problems/largest-magic-square "最大的幻方") | [Go](problems/largest-magic-square) | Medium |
-| <span id="1894">1894</span> | [Find the Student that Will Replace the Chalk](https://leetcode.com/problems/find-the-student-that-will-replace-the-chalk "找到需要补充粉笔的学生编号") | [Go](problems/find-the-student-that-will-replace-the-chalk) | Medium |
-| <span id="1893">1893</span> | [Check if All the Integers in a Range Are Covered](https://leetcode.com/problems/check-if-all-the-integers-in-a-range-are-covered "检查是否区域内所有整数都被覆盖") | [Go](problems/check-if-all-the-integers-in-a-range-are-covered) | Easy |
-| <span id="1892">1892</span> | [Page Recommendations II](https://leetcode.com/problems/page-recommendations-ii "页面推荐Ⅱ") 🔒 | [MySQL](problems/page-recommendations-ii) | Hard |
-| <span id="1891">1891</span> | [Cutting Ribbons](https://leetcode.com/problems/cutting-ribbons "割绳子") 🔒 | [Go](problems/cutting-ribbons) | Medium |
-| <span id="1890">1890</span> | [The Latest Login in 2020](https://leetcode.com/problems/the-latest-login-in-2020 "2020年最后一次登录") 🔒 | [MySQL](problems/the-latest-login-in-2020) | Easy |
-| <span id="1889">1889</span> | [Minimum Space Wasted From Packaging](https://leetcode.com/problems/minimum-space-wasted-from-packaging "装包裹的最小浪费空间") | [Go](problems/minimum-space-wasted-from-packaging) | Hard |
-| <span id="1888">1888</span> | [Minimum Number of Flips to Make the Binary String Alternating](https://leetcode.com/problems/minimum-number-of-flips-to-make-the-binary-string-alternating "使二进制字符串字符交替的最少反转次数") | [Go](problems/minimum-number-of-flips-to-make-the-binary-string-alternating) | Medium |
-| <span id="1887">1887</span> | [Reduction Operations to Make the Array Elements Equal](https://leetcode.com/problems/reduction-operations-to-make-the-array-elements-equal "使数组元素相等的减少操作次数") | [Go](problems/reduction-operations-to-make-the-array-elements-equal) | Medium |
-| <span id="1886">1886</span> | [Determine Whether Matrix Can Be Obtained By Rotation](https://leetcode.com/problems/determine-whether-matrix-can-be-obtained-by-rotation "判断矩阵经轮转后是否一致") | [Go](problems/determine-whether-matrix-can-be-obtained-by-rotation) | Easy |
-| <span id="1885">1885</span> | [Count Pairs in Two Arrays](https://leetcode.com/problems/count-pairs-in-two-arrays "统计数对") 🔒 | [Go](problems/count-pairs-in-two-arrays) | Medium |
-| <span id="1884">1884</span> | [Egg Drop With 2 Eggs and N Floors](https://leetcode.com/problems/egg-drop-with-2-eggs-and-n-floors "鸡蛋掉落-两枚鸡蛋") | [Go](problems/egg-drop-with-2-eggs-and-n-floors) | Medium |
-| <span id="1883">1883</span> | [Minimum Skips to Arrive at Meeting On Time](https://leetcode.com/problems/minimum-skips-to-arrive-at-meeting-on-time "准时抵达会议现场的最小跳过休息次数") | [Go](problems/minimum-skips-to-arrive-at-meeting-on-time) | Hard |
-| <span id="1882">1882</span> | [Process Tasks Using Servers](https://leetcode.com/problems/process-tasks-using-servers "使用服务器处理任务") | [Go](problems/process-tasks-using-servers) | Medium |
-| <span id="1881">1881</span> | [Maximum Value after Insertion](https://leetcode.com/problems/maximum-value-after-insertion "插入后的最大值") | [Go](problems/maximum-value-after-insertion) | Medium |
-| <span id="1880">1880</span> | [Check if Word Equals Summation of Two Words](https://leetcode.com/problems/check-if-word-equals-summation-of-two-words "检查某单词是否等于两单词之和") | [Go](problems/check-if-word-equals-summation-of-two-words) | Easy |
-| <span id="1879">1879</span> | [Minimum XOR Sum of Two Arrays](https://leetcode.com/problems/minimum-xor-sum-of-two-arrays "两个数组最小的异或值之和") | [Go](problems/minimum-xor-sum-of-two-arrays) | Hard |
-| <span id="1878">1878</span> | [Get Biggest Three Rhombus Sums in a Grid](https://leetcode.com/problems/get-biggest-three-rhombus-sums-in-a-grid "矩阵中最大的三个菱形和") | [Go](problems/get-biggest-three-rhombus-sums-in-a-grid) | Medium |
-| <span id="1877">1877</span> | [Minimize Maximum Pair Sum in Array](https://leetcode.com/problems/minimize-maximum-pair-sum-in-array "数组中最大数对和的最小值") | [Go](problems/minimize-maximum-pair-sum-in-array) | Medium |
-| <span id="1876">1876</span> | [Substrings of Size Three with Distinct Characters](https://leetcode.com/problems/substrings-of-size-three-with-distinct-characters "长度为三且各字符不同的子字符串") | [Go](problems/substrings-of-size-three-with-distinct-characters) | Easy |
-| <span id="1875">1875</span> | [Group Employees of the Same Salary](https://leetcode.com/problems/group-employees-of-the-same-salary "将工资相同的雇员分组") 🔒 | [MySQL](problems/group-employees-of-the-same-salary) | Medium |
-| <span id="1874">1874</span> | [Minimize Product Sum of Two Arrays](https://leetcode.com/problems/minimize-product-sum-of-two-arrays "两个数组的最小乘积和") 🔒 | [Go](problems/minimize-product-sum-of-two-arrays) | Medium |
-| <span id="1873">1873</span> | [Calculate Special Bonus](https://leetcode.com/problems/calculate-special-bonus "计算特殊奖金") 🔒 | [MySQL](problems/calculate-special-bonus) | Easy |
-| <span id="1872">1872</span> | [Stone Game VIII](https://leetcode.com/problems/stone-game-viii "石子游戏 VIII") | [Go](problems/stone-game-viii) | Hard |
-| <span id="1871">1871</span> | [Jump Game VII](https://leetcode.com/problems/jump-game-vii "跳跃游戏 VII") | [Go](problems/jump-game-vii) | Medium |
-| <span id="1870">1870</span> | [Minimum Speed to Arrive on Time](https://leetcode.com/problems/minimum-speed-to-arrive-on-time "准时到达的列车最小时速") | [Go](problems/minimum-speed-to-arrive-on-time) | Medium |
-| <span id="1869">1869</span> | [Longer Contiguous Segments of Ones than Zeros](https://leetcode.com/problems/longer-contiguous-segments-of-ones-than-zeros "哪种连续子字符串更长") | [Go](problems/longer-contiguous-segments-of-ones-than-zeros) | Easy |
-| <span id="1868">1868</span> | [Product of Two Run-Length Encoded Arrays](https://leetcode.com/problems/product-of-two-run-length-encoded-arrays "两个行程编码数组的积") 🔒 | [Go](problems/product-of-two-run-length-encoded-arrays) | Medium |
-| <span id="1867">1867</span> | [Orders With Maximum Quantity Above Average](https://leetcode.com/problems/orders-with-maximum-quantity-above-average "最大数量高于平均水平的订单") 🔒 | [MySQL](problems/orders-with-maximum-quantity-above-average) | Medium |
-| <span id="1866">1866</span> | [Number of Ways to Rearrange Sticks With K Sticks Visible](https://leetcode.com/problems/number-of-ways-to-rearrange-sticks-with-k-sticks-visible "恰有 K 根木棍可以看到的排列数目") | [Go](problems/number-of-ways-to-rearrange-sticks-with-k-sticks-visible) | Hard |
-| <span id="1865">1865</span> | [Finding Pairs With a Certain Sum](https://leetcode.com/problems/finding-pairs-with-a-certain-sum "找出和为指定值的下标对") | [Go](problems/finding-pairs-with-a-certain-sum) | Medium |
-| <span id="1864">1864</span> | [Minimum Number of Swaps to Make the Binary String Alternating](https://leetcode.com/problems/minimum-number-of-swaps-to-make-the-binary-string-alternating "构成交替字符串需要的最小交换次数") | [Go](problems/minimum-number-of-swaps-to-make-the-binary-string-alternating) | Medium |
-| <span id="1863">1863</span> | [Sum of All Subset XOR Totals](https://leetcode.com/problems/sum-of-all-subset-xor-totals "找出所有子集的异或总和再求和") | [Go](problems/sum-of-all-subset-xor-totals) | Easy |
-| <span id="1862">1862</span> | [Sum of Floored Pairs](https://leetcode.com/problems/sum-of-floored-pairs "向下取整数对和") | [Go](problems/sum-of-floored-pairs) | Hard |
-| <span id="1861">1861</span> | [Rotating the Box](https://leetcode.com/problems/rotating-the-box "旋转盒子") | [Go](problems/rotating-the-box) | Medium |
-| <span id="1860">1860</span> | [Incremental Memory Leak](https://leetcode.com/problems/incremental-memory-leak "增长的内存泄露") | [Go](problems/incremental-memory-leak) | Medium |
-| <span id="1859">1859</span> | [Sorting the Sentence](https://leetcode.com/problems/sorting-the-sentence "将句子排序") | [Go](problems/sorting-the-sentence) | Easy |
-| <span id="1858">1858</span> | [Longest Word With All Prefixes](https://leetcode.com/problems/longest-word-with-all-prefixes "包含所有前缀的最长单词") 🔒 | [Go](problems/longest-word-with-all-prefixes) | Medium |
-| <span id="1857">1857</span> | [Largest Color Value in a Directed Graph](https://leetcode.com/problems/largest-color-value-in-a-directed-graph "有向图中最大颜色值") | [Go](problems/largest-color-value-in-a-directed-graph) | Hard |
-| <span id="1856">1856</span> | [Maximum Subarray Min-Product](https://leetcode.com/problems/maximum-subarray-min-product "子数组最小乘积的最大值") | [Go](problems/maximum-subarray-min-product) | Medium |
-| <span id="1855">1855</span> | [Maximum Distance Between a Pair of Values](https://leetcode.com/problems/maximum-distance-between-a-pair-of-values "下标对中的最大距离") | [Go](problems/maximum-distance-between-a-pair-of-values) | Medium |
-| <span id="1854">1854</span> | [Maximum Population Year](https://leetcode.com/problems/maximum-population-year "人口最多的年份") | [Go](problems/maximum-population-year) | Easy |
-| <span id="1853">1853</span> | [Convert Date Format](https://leetcode.com/problems/convert-date-format "转换日期格式") 🔒 | [MySQL](problems/convert-date-format) | Easy |
-| <span id="1852">1852</span> | [Distinct Numbers in Each Subarray](https://leetcode.com/problems/distinct-numbers-in-each-subarray "每个子数组的数字种类数") 🔒 | [Go](problems/distinct-numbers-in-each-subarray) | Medium |
-| <span id="1851">1851</span> | [Minimum Interval to Include Each Query](https://leetcode.com/problems/minimum-interval-to-include-each-query "包含每个查询的最小区间") | [Go](problems/minimum-interval-to-include-each-query) | Hard |
-| <span id="1850">1850</span> | [Minimum Adjacent Swaps to Reach the Kth Smallest Number](https://leetcode.com/problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number "邻位交换的最小次数") | [Go](problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number) | Medium |
-| <span id="1849">1849</span> | [Splitting a String Into Descending Consecutive Values](https://leetcode.com/problems/splitting-a-string-into-descending-consecutive-values "将字符串拆分为递减的连续值") | [Go](problems/splitting-a-string-into-descending-consecutive-values) | Medium |
-| <span id="1848">1848</span> | [Minimum Distance to the Target Element](https://leetcode.com/problems/minimum-distance-to-the-target-element "到目标元素的最小距离") | [Go](problems/minimum-distance-to-the-target-element) | Easy |
-| <span id="1847">1847</span> | [Closest Room](https://leetcode.com/problems/closest-room "最近的房间") | [Go](problems/closest-room) | Hard |
-| <span id="1846">1846</span> | [Maximum Element After Decreasing and Rearranging](https://leetcode.com/problems/maximum-element-after-decreasing-and-rearranging "减小和重新排列数组后的最大元素") | [Go](problems/maximum-element-after-decreasing-and-rearranging) | Medium |
-| <span id="1845">1845</span> | [Seat Reservation Manager](https://leetcode.com/problems/seat-reservation-manager "座位预约管理系统") | [Go](problems/seat-reservation-manager) | Medium |
-| <span id="1844">1844</span> | [Replace All Digits with Characters](https://leetcode.com/problems/replace-all-digits-with-characters "将所有数字用字符替换") | [Go](problems/replace-all-digits-with-characters) | Easy |
-| <span id="1843">1843</span> | [Suspicious Bank Accounts](https://leetcode.com/problems/suspicious-bank-accounts "可疑银行账户") 🔒 | [MySQL](problems/suspicious-bank-accounts) | Medium |
-| <span id="1842">1842</span> | [Next Palindrome Using Same Digits](https://leetcode.com/problems/next-palindrome-using-same-digits "下个由相同数字构成的回文串") 🔒 | [Go](problems/next-palindrome-using-same-digits) | Hard |
-| <span id="1841">1841</span> | [League Statistics](https://leetcode.com/problems/league-statistics "联赛信息统计") 🔒 | [MySQL](problems/league-statistics) | Medium |
-| <span id="1840">1840</span> | [Maximum Building Height](https://leetcode.com/problems/maximum-building-height "最高建筑高度") | [Go](problems/maximum-building-height) | Hard |
-| <span id="1839">1839</span> | [Longest Substring Of All Vowels in Order](https://leetcode.com/problems/longest-substring-of-all-vowels-in-order "所有元音按顺序排布的最长子字符串") | [Go](problems/longest-substring-of-all-vowels-in-order) | Medium |
-| <span id="1838">1838</span> | [Frequency of the Most Frequent Element](https://leetcode.com/problems/frequency-of-the-most-frequent-element "最高频元素的频数") | [Go](problems/frequency-of-the-most-frequent-element) | Medium |
-| <span id="1837">1837</span> | [Sum of Digits in Base K](https://leetcode.com/problems/sum-of-digits-in-base-k "K 进制表示下的各位数字总和") | [Go](problems/sum-of-digits-in-base-k) | Easy |
-| <span id="1836">1836</span> | [Remove Duplicates From an Unsorted Linked List](https://leetcode.com/problems/remove-duplicates-from-an-unsorted-linked-list "从未排序的链表中移除重复元素") 🔒 | [Go](problems/remove-duplicates-from-an-unsorted-linked-list) | Medium |
-| <span id="1835">1835</span> | [Find XOR Sum of All Pairs Bitwise AND](https://leetcode.com/problems/find-xor-sum-of-all-pairs-bitwise-and "所有数对按位与结果的异或和") | [Go](problems/find-xor-sum-of-all-pairs-bitwise-and) | Hard |
-| <span id="1834">1834</span> | [Single-Threaded CPU](https://leetcode.com/problems/single-threaded-cpu "单线程 CPU") | [Go](problems/single-threaded-cpu) | Medium |
-| <span id="1833">1833</span> | [Maximum Ice Cream Bars](https://leetcode.com/problems/maximum-ice-cream-bars "雪糕的最大数量") | [Go](problems/maximum-ice-cream-bars) | Medium |
-| <span id="1832">1832</span> | [Check if the Sentence Is Pangram](https://leetcode.com/problems/check-if-the-sentence-is-pangram "判断句子是否为全字母句") | [Go](problems/check-if-the-sentence-is-pangram) | Easy |
-| <span id="1831">1831</span> | [Maximum Transaction Each Day](https://leetcode.com/problems/maximum-transaction-each-day "每天的最大交易") 🔒 | [MySQL](problems/maximum-transaction-each-day) | Medium |
-| <span id="1830">1830</span> | [Minimum Number of Operations to Make String Sorted](https://leetcode.com/problems/minimum-number-of-operations-to-make-string-sorted "使字符串有序的最少操作次数") | [Go](problems/minimum-number-of-operations-to-make-string-sorted) | Hard |
-| <span id="1829">1829</span> | [Maximum XOR for Each Query](https://leetcode.com/problems/maximum-xor-for-each-query "每个查询的最大异或值") | [Go](problems/maximum-xor-for-each-query) | Medium |
-| <span id="1828">1828</span> | [Queries on Number of Points Inside a Circle](https://leetcode.com/problems/queries-on-number-of-points-inside-a-circle "统计一个圆中点的数目") | [Go](problems/queries-on-number-of-points-inside-a-circle) | Medium |
-| <span id="1827">1827</span> | [Minimum Operations to Make the Array Increasing](https://leetcode.com/problems/minimum-operations-to-make-the-array-increasing "最少操作使数组递增") | [Go](problems/minimum-operations-to-make-the-array-increasing) | Easy |
-| <span id="1826">1826</span> | [Faulty Sensor](https://leetcode.com/problems/faulty-sensor "有缺陷的传感器") 🔒 | [Go](problems/faulty-sensor) | Easy |
-| <span id="1825">1825</span> | [Finding MK Average](https://leetcode.com/problems/finding-mk-average "求出 MK 平均值") | [Go](problems/finding-mk-average) | Hard |
-| <span id="1824">1824</span> | [Minimum Sideway Jumps](https://leetcode.com/problems/minimum-sideway-jumps "最少侧跳次数") | [Go](problems/minimum-sideway-jumps) | Medium |
-| <span id="1823">1823</span> | [Find the Winner of the Circular Game](https://leetcode.com/problems/find-the-winner-of-the-circular-game "找出游戏的获胜者") | [Go](problems/find-the-winner-of-the-circular-game) | Medium |
-| <span id="1822">1822</span> | [Sign of the Product of an Array](https://leetcode.com/problems/sign-of-the-product-of-an-array "数组元素积的符号") | [Go](problems/sign-of-the-product-of-an-array) | Easy |
-| <span id="1821">1821</span> | [Find Customers With Positive Revenue this Year](https://leetcode.com/problems/find-customers-with-positive-revenue-this-year "寻找今年具有正收入的客户") 🔒 | [MySQL](problems/find-customers-with-positive-revenue-this-year) | Easy |
-| <span id="1820">1820</span> | [Maximum Number of Accepted Invitations](https://leetcode.com/problems/maximum-number-of-accepted-invitations "最多邀请的个数") 🔒 | [Go](problems/maximum-number-of-accepted-invitations) | Medium |
-| <span id="1819">1819</span> | [Number of Different Subsequences GCDs](https://leetcode.com/problems/number-of-different-subsequences-gcds "序列中不同最大公约数的数目") | [Go](problems/number-of-different-subsequences-gcds) | Hard |
-| <span id="1818">1818</span> | [Minimum Absolute Sum Difference](https://leetcode.com/problems/minimum-absolute-sum-difference "绝对差值和") | [Go](problems/minimum-absolute-sum-difference) | Medium |
-| <span id="1817">1817</span> | [Finding the Users Active Minutes](https://leetcode.com/problems/finding-the-users-active-minutes "查找用户活跃分钟数") | [Go](problems/finding-the-users-active-minutes) | Medium |
-| <span id="1816">1816</span> | [Truncate Sentence](https://leetcode.com/problems/truncate-sentence "截断句子") | [Go](problems/truncate-sentence) | Easy |
-| <span id="1815">1815</span> | [Maximum Number of Groups Getting Fresh Donuts](https://leetcode.com/problems/maximum-number-of-groups-getting-fresh-donuts "得到新鲜甜甜圈的最多组数") | [Go](problems/maximum-number-of-groups-getting-fresh-donuts) | Hard |
-| <span id="1814">1814</span> | [Count Nice Pairs in an Array](https://leetcode.com/problems/count-nice-pairs-in-an-array "统计一个数组中好对子的数目") | [Go](problems/count-nice-pairs-in-an-array) | Medium |
-| <span id="1813">1813</span> | [Sentence Similarity III](https://leetcode.com/problems/sentence-similarity-iii "句子相似性 III") | [Go](problems/sentence-similarity-iii) | Medium |
-| <span id="1812">1812</span> | [Determine Color of a Chessboard Square](https://leetcode.com/problems/determine-color-of-a-chessboard-square "判断国际象棋棋盘中一个格子的颜色") | [Go](problems/determine-color-of-a-chessboard-square) | Easy |
-| <span id="1811">1811</span> | [Find Interview Candidates](https://leetcode.com/problems/find-interview-candidates "寻找面试候选人") 🔒 | [MySQL](problems/find-interview-candidates) | Medium |
-| <span id="1810">1810</span> | [Minimum Path Cost in a Hidden Grid](https://leetcode.com/problems/minimum-path-cost-in-a-hidden-grid "隐藏网格下的最小消耗路径") 🔒 | [Go](problems/minimum-path-cost-in-a-hidden-grid) | Medium |
-| <span id="1809">1809</span> | [Ad-Free Sessions](https://leetcode.com/problems/ad-free-sessions "没有广告的剧集") 🔒 | [MySQL](problems/ad-free-sessions) | Easy |
-| <span id="1808">1808</span> | [Maximize Number of Nice Divisors](https://leetcode.com/problems/maximize-number-of-nice-divisors "好因子的最大数目") | [Go](problems/maximize-number-of-nice-divisors) | Hard |
-| <span id="1807">1807</span> | [Evaluate the Bracket Pairs of a String](https://leetcode.com/problems/evaluate-the-bracket-pairs-of-a-string "替换字符串中的括号内容") | [Go](problems/evaluate-the-bracket-pairs-of-a-string) | Medium |
-| <span id="1806">1806</span> | [Minimum Number of Operations to Reinitialize a Permutation](https://leetcode.com/problems/minimum-number-of-operations-to-reinitialize-a-permutation "还原排列的最少操作步数") | [Go](problems/minimum-number-of-operations-to-reinitialize-a-permutation) | Medium |
-| <span id="1805">1805</span> | [Number of Different Integers in a String](https://leetcode.com/problems/number-of-different-integers-in-a-string "字符串中不同整数的数目") | [Go](problems/number-of-different-integers-in-a-string) | Easy |
-| <span id="1804">1804</span> | [Implement Trie II (Prefix Tree)](https://leetcode.com/problems/implement-trie-ii-prefix-tree "实现 Trie （前缀树） II") 🔒 | [Go](problems/implement-trie-ii-prefix-tree) | Medium |
-| <span id="1803">1803</span> | [Count Pairs With XOR in a Range](https://leetcode.com/problems/count-pairs-with-xor-in-a-range "统计异或值在范围内的数对有多少") | [Go](problems/count-pairs-with-xor-in-a-range) | Hard |
-| <span id="1802">1802</span> | [Maximum Value at a Given Index in a Bounded Array](https://leetcode.com/problems/maximum-value-at-a-given-index-in-a-bounded-array "有界数组中指定下标处的最大值") | [Go](problems/maximum-value-at-a-given-index-in-a-bounded-array) | Medium |
-| <span id="1801">1801</span> | [Number of Orders in the Backlog](https://leetcode.com/problems/number-of-orders-in-the-backlog "积压订单中的订单总数") | [Go](problems/number-of-orders-in-the-backlog) | Medium |
+# &copy;2019 Openset. All rights reserved.
diff --git a/_config.yml b/_config.yml
new file mode 100644
index 000000000..1338eb460
--- /dev/null
+++ b/_config.yml
@@ -0,0 +1,4 @@
+lang:   zh-CN
+owner_name: Openset
+google_analytics: UA-103591670-1
+theme: jekyll-theme-cayman
diff --git a/_layouts/default.html b/_layouts/default.html
new file mode 100644
index 000000000..ee38e760e
--- /dev/null
+++ b/_layouts/default.html
@@ -0,0 +1,55 @@
+<!DOCTYPE html>
+<html lang="{{ site.lang | default: "en-US" }}">
+<head>
+    <meta charset="UTF-8">
+    {% seo %}
+    <meta name="description"
+          content="{{ page.description | default: site.description | default: site.github.project_tagline }}"/>
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <meta name="theme-color" content="#157878">
+    <link href='https://fonts.googleapis.com/css?family=Open+Sans:400,700' rel='stylesheet' type='text/css'>
+    <link rel="stylesheet" href="{{ '/assets/css/style.css?v=' | append: site.github.build_revision | relative_url }}">
+    <link rel="shortcut icon" href="https://openset.github.io/favicon.ico">
+</head>
+<body>
+
+<section class="main-content">
+
+    {{ content }}
+
+    <footer class="site-footer">
+    <span class="site-footer-owner">
+        <span style="float: left;width:76%; max-width:400px;">&copy;{{ site.time | date: "%Y" }} {{ site.owner_name }}. All rights reserved.</span>
+        <a href="{{ site.github.repository_url | default: site.github.owner_url }}" target="_blank">
+            <svg height="24" version="1.1" viewBox="0 0 16 16" width="24">
+                <path fill-rule="evenodd"
+                      d="M8 0C3.58 0 0 3.58 0 8c0 3.54 2.29 6.53 5.47 7.59.4.07.55-.17.55-.38 0-.19-.01-.82-.01-1.49-2.01.37-2.53-.49-2.69-.94-.09-.23-.48-.94-.82-1.13-.28-.15-.68-.52-.01-.53.63-.01 1.08.58 1.23.82.72 1.21 1.87.87 2.33.66.07-.52.28-.87.51-1.07-1.78-.2-3.64-.89-3.64-3.95 0-.87.31-1.59.82-2.15-.08-.2-.36-1.02.08-2.12 0 0 .67-.21 2.2.82.64-.18 1.32-.27 2-.27.68 0 1.36.09 2 .27 1.53-1.04 2.2-.82 2.2-.82.44 1.1.16 1.92.08 2.12.51.56.82 1.27.82 2.15 0 3.07-1.87 3.75-3.65 3.95.29.25.54.73.54 1.48 0 1.07-.01 1.93-.01 2.2 0 .21.15.46.55.38A8.013 8.013 0 0 0 16 8c0-4.42-3.58-8-8-8z"></path>
+            </svg>
+        </a>
+        <span style="float: right;">
+            <a href="javascript:window.scrollTo(0,0);">TOP</a>
+        </span>
+    </span>
+    </footer>
+</section>
+
+{% if site.google_analytics %}
+<script type="text/javascript">
+    (function (i, s, o, g, r, a, m) {
+        i['GoogleAnalyticsObject'] = r;
+        i[r] = i[r] || function () {
+                    (i[r].q = i[r].q || []).push(arguments)
+                }, i[r].l = 1 * new Date();
+        a = s.createElement(o),
+                m = s.getElementsByTagName(o)[0];
+        a.async = 1;
+        a.src = g;
+        m.parentNode.insertBefore(a, m)
+    })(window, document, 'script', '//www.google-analytics.com/analytics.js', 'ga');
+
+    ga('create', '{{ site.google_analytics }}', 'auto');
+    ga('send', 'pageview');
+</script>
+{% endif %}
+</body>
+</html>
diff --git a/go.mod b/go.mod
deleted file mode 100644
index 5eb7c7282..000000000
--- a/go.mod
+++ /dev/null
@@ -1,3 +0,0 @@
-module github.com/awesee/leetcode
-
-go 1.16
diff --git a/helper/README.md b/helper/README.md
deleted file mode 100644
index b5d445180..000000000
--- a/helper/README.md
+++ /dev/null
@@ -1,25 +0,0 @@
-<!--|This file generated by command(leetcode helper); DO NOT EDIT.         |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-# Helper
-
-```text
-leetcode is a tool for managing leetcode source code.
-
-Usage:
-	leetcode <command> [arguments]
-The commands are:
-	question    	build problem solution file
-	open        	open a problem solution in browser
-	test        	run go test
-	update      	update or upgrade self
-	clean       	remove cached files
-	version     	print leetcode version
-	help        	show command usage
-
-Use "leetcode help <command>" for more information about a command.
-```
diff --git a/index.md b/index.md
new file mode 100644
index 000000000..33bb8501e
--- /dev/null
+++ b/index.md
@@ -0,0 +1,1029 @@
+<!--|This file generated by command(leetcode page); DO NOT EDIT.           |-->
+<!--+----------------------------------------------------------------------+-->
+<!--|@author    Openset <openset.wang@gmail.com>                           |-->
+<!--|@link      https://github.com/openset                                 |-->
+<!--|@home      https://github.com/openset/leetcode                        |-->
+<!--+----------------------------------------------------------------------+-->
+
+# [LeetCode](https://openset.github.io/leetcode)
+LeetCode Problems' Solutions
+[[话题分类](https://github.com/openset/leetcode/blob/master/tag/README.md)]
+
+[![Build Status](https://travis-ci.org/openset/leetcode.svg?branch=master)](https://travis-ci.org/openset/leetcode)
+[![codecov](https://codecov.io/gh/openset/leetcode/branch/master/graph/badge.svg)](https://codecov.io/gh/openset/leetcode)
+[![Go Report Card](https://goreportcard.com/badge/github.com/openset/leetcode)](https://goreportcard.com/report/github.com/openset/leetcode)
+[![GitHub contributors](https://img.shields.io/github/contributors/openset/leetcode.svg)](https://github.com/openset/leetcode/graphs/contributors)
+[![license](https://img.shields.io/github/license/openset/leetcode.svg)](https://github.com/openset/leetcode/blob/master/LICENSE)
+[![GitHub code size in bytes](https://img.shields.io/github/languages/code-size/openset/leetcode.svg?colorB=green)](https://github.com/openset/leetcode/archive/master.zip)
+
+<table><thead>
+<tr>
+	<th align="center"><a href="#1">[1-50]</a></th>
+	<th align="center"><a href="#51">[51-100]</a></th>
+	<th align="center"><a href="#101">[101-150]</a></th>
+	<th align="center"><a href="#151">[151-200]</a></th>
+	<th align="center"><a href="#201">[201-250]</a></th>
+	<th align="center"><a href="#251">[251-300]</a></th>
+</tr>
+<tr>
+	<th align="center"><a href="#301">[301-350]</a></th>
+	<th align="center"><a href="#351">[351-400]</a></th>
+	<th align="center"><a href="#401">[401-450]</a></th>
+	<th align="center"><a href="#451">[451-500]</a></th>
+	<th align="center"><a href="#501">[501-550]</a></th>
+	<th align="center"><a href="#551">[551-600]</a></th>
+</tr>
+<tr>
+	<th align="center"><a href="#601">[601-650]</a></th>
+	<th align="center"><a href="#651">[651-700]</a></th>
+	<th align="center"><a href="#701">[701-750]</a></th>
+	<th align="center"><a href="#751">[751-800]</a></th>
+	<th align="center"><a href="#801">[801-850]</a></th>
+	<th align="center"><a href="#851">[851-900]</a></th>
+</tr>
+<tr>
+	<th align="center"><a href="#901">[901-950]</a></th>
+	<th align="center"><a href="#951">[951-1000]</a></th>
+	<th align="center"><a href="#1001">[1001-1050]</a></th>
+	<th align="center"><a href="#1051">[1051-1100]</a></th>
+	<th align="center"><a href="#1101">[1101-1150]</a></th>
+	<th align="center"><a href="#1151">[1151-1200]</a></th>
+</tr>
+</thead></table>
+
+| # | Title | Solution | Difficulty |
+| :-: | - | - | :-: |
+| <span id="980">980</span> | [Unique Paths III](https://leetcode.com/problems/unique-paths-iii "不同路径 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-paths-iii) | Hard |
+| <span id="979">979</span> | [Distribute Coins in Binary Tree](https://leetcode.com/problems/distribute-coins-in-binary-tree "在二叉树中分配硬币") | [Go](https://github.com/openset/leetcode/tree/master/problems/distribute-coins-in-binary-tree) | Medium |
+| <span id="978">978</span> | [Longest Turbulent Subarray](https://leetcode.com/problems/longest-turbulent-subarray "最长湍流子数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-turbulent-subarray) | Medium |
+| <span id="977">977</span> | [Squares of a Sorted Array](https://leetcode.com/problems/squares-of-a-sorted-array "有序数组的平方") | [Go](https://github.com/openset/leetcode/tree/master/problems/squares-of-a-sorted-array) | Easy |
+| <span id="976">976</span> | [Largest Perimeter Triangle](https://leetcode.com/problems/largest-perimeter-triangle "三角形的最大周长") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-perimeter-triangle) | Easy |
+| <span id="975">975</span> | [Odd Even Jump](https://leetcode.com/problems/odd-even-jump "奇偶跳") | [Go](https://github.com/openset/leetcode/tree/master/problems/odd-even-jump) | Hard |
+| <span id="974">974</span> | [Subarray Sums Divisible by K](https://leetcode.com/problems/subarray-sums-divisible-by-k "和可被 K 整除的子数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/subarray-sums-divisible-by-k) | Medium |
+| <span id="973">973</span> | [K Closest Points to Origin](https://leetcode.com/problems/k-closest-points-to-origin "最接近原点的 K 个点") | [Go](https://github.com/openset/leetcode/tree/master/problems/k-closest-points-to-origin) | Easy |
+| <span id="972">972</span> | [Equal Rational Numbers](https://leetcode.com/problems/equal-rational-numbers "相等的有理数") | [Go](https://github.com/openset/leetcode/tree/master/problems/equal-rational-numbers) | Hard |
+| <span id="971">971</span> | [Flip Binary Tree To Match Preorder Traversal](https://leetcode.com/problems/flip-binary-tree-to-match-preorder-traversal "翻转二叉树以匹配先序遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/flip-binary-tree-to-match-preorder-traversal) | Medium |
+| <span id="970">970</span> | [Powerful Integers](https://leetcode.com/problems/powerful-integers "强整数") | [Go](https://github.com/openset/leetcode/tree/master/problems/powerful-integers) | Easy |
+| <span id="969">969</span> | [Pancake Sorting](https://leetcode.com/problems/pancake-sorting "煎饼排序") | [Go](https://github.com/openset/leetcode/tree/master/problems/pancake-sorting) | Medium |
+| <span id="968">968</span> | [Binary Tree Cameras](https://leetcode.com/problems/binary-tree-cameras "监控二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-cameras) | Hard |
+| <span id="967">967</span> | [Numbers With Same Consecutive Differences](https://leetcode.com/problems/numbers-with-same-consecutive-differences "连续差相同的数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/numbers-with-same-consecutive-differences) | Medium |
+| <span id="966">966</span> | [Vowel Spellchecker](https://leetcode.com/problems/vowel-spellchecker "元音拼写检查器") | [Go](https://github.com/openset/leetcode/tree/master/problems/vowel-spellchecker) | Medium |
+| <span id="965">965</span> | [Univalued Binary Tree](https://leetcode.com/problems/univalued-binary-tree "单值二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/univalued-binary-tree) | Easy |
+| <span id="964">964</span> | [Least Operators to Express Number](https://leetcode.com/problems/least-operators-to-express-number "表示数字的最少运算符") | [Go](https://github.com/openset/leetcode/tree/master/problems/least-operators-to-express-number) | Hard |
+| <span id="963">963</span> | [Minimum Area Rectangle II](https://leetcode.com/problems/minimum-area-rectangle-ii "最小面积矩形 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-area-rectangle-ii) | Medium |
+| <span id="962">962</span> | [Maximum Width Ramp](https://leetcode.com/problems/maximum-width-ramp "最大宽度坡") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-width-ramp) | Medium |
+| <span id="961">961</span> | [N-Repeated Element in Size 2N Array](https://leetcode.com/problems/n-repeated-element-in-size-2n-array "重复 N 次的元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/n-repeated-element-in-size-2n-array) | Easy |
+| <span id="960">960</span> | [Delete Columns to Make Sorted III](https://leetcode.com/problems/delete-columns-to-make-sorted-iii "删列造序 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/delete-columns-to-make-sorted-iii) | Hard |
+| <span id="959">959</span> | [Regions Cut By Slashes](https://leetcode.com/problems/regions-cut-by-slashes "由斜杠划分区域") | [Go](https://github.com/openset/leetcode/tree/master/problems/regions-cut-by-slashes) | Medium |
+| <span id="958">958</span> | [Check Completeness of a Binary Tree](https://leetcode.com/problems/check-completeness-of-a-binary-tree "二叉树的完全性检验") | [Go](https://github.com/openset/leetcode/tree/master/problems/check-completeness-of-a-binary-tree) | Medium |
+| <span id="957">957</span> | [Prison Cells After N Days](https://leetcode.com/problems/prison-cells-after-n-days "N 天后的牢房") | [Go](https://github.com/openset/leetcode/tree/master/problems/prison-cells-after-n-days) | Medium |
+| <span id="956">956</span> | [Tallest Billboard](https://leetcode.com/problems/tallest-billboard "最高的广告牌") | [Go](https://github.com/openset/leetcode/tree/master/problems/tallest-billboard) | Hard |
+| <span id="955">955</span> | [Delete Columns to Make Sorted II](https://leetcode.com/problems/delete-columns-to-make-sorted-ii "删列造序 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/delete-columns-to-make-sorted-ii) | Medium |
+| <span id="954">954</span> | [Array of Doubled Pairs](https://leetcode.com/problems/array-of-doubled-pairs "二倍数对数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/array-of-doubled-pairs) | Medium |
+| <span id="953">953</span> | [Verifying an Alien Dictionary](https://leetcode.com/problems/verifying-an-alien-dictionary "验证外星语词典") | [Go](https://github.com/openset/leetcode/tree/master/problems/verifying-an-alien-dictionary) | Easy |
+| <span id="952">952</span> | [Largest Component Size by Common Factor](https://leetcode.com/problems/largest-component-size-by-common-factor "按公因数计算最大组件大小") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-component-size-by-common-factor) | Hard |
+| <span id="951">951</span> | [Flip Equivalent Binary Trees](https://leetcode.com/problems/flip-equivalent-binary-trees "翻转等价二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/flip-equivalent-binary-trees) | Medium |
+| <span id="950">950</span> | [Reveal Cards In Increasing Order](https://leetcode.com/problems/reveal-cards-in-increasing-order "按递增顺序显示卡牌") | [Go](https://github.com/openset/leetcode/tree/master/problems/reveal-cards-in-increasing-order) | Medium |
+| <span id="949">949</span> | [Largest Time for Given Digits](https://leetcode.com/problems/largest-time-for-given-digits "给定数字能组成的最大时间") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-time-for-given-digits) | Easy |
+| <span id="948">948</span> | [Bag of Tokens](https://leetcode.com/problems/bag-of-tokens "令牌放置") | [Go](https://github.com/openset/leetcode/tree/master/problems/bag-of-tokens) | Medium |
+| <span id="947">947</span> | [Most Stones Removed with Same Row or Column](https://leetcode.com/problems/most-stones-removed-with-same-row-or-column "移除最多的同行或同列石头") | [Go](https://github.com/openset/leetcode/tree/master/problems/most-stones-removed-with-same-row-or-column) | Medium |
+| <span id="946">946</span> | [Validate Stack Sequences](https://leetcode.com/problems/validate-stack-sequences "验证栈序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/validate-stack-sequences) | Medium |
+| <span id="945">945</span> | [Minimum Increment to Make Array Unique](https://leetcode.com/problems/minimum-increment-to-make-array-unique "使数组唯一的最小增量") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-increment-to-make-array-unique) | Medium |
+| <span id="944">944</span> | [Delete Columns to Make Sorted](https://leetcode.com/problems/delete-columns-to-make-sorted "删列造序") | [Go](https://github.com/openset/leetcode/tree/master/problems/delete-columns-to-make-sorted) | Easy |
+| <span id="943">943</span> | [Find the Shortest Superstring](https://leetcode.com/problems/find-the-shortest-superstring "最短超级串") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-the-shortest-superstring) | Hard |
+| <span id="942">942</span> | [DI String Match](https://leetcode.com/problems/di-string-match "增减字符串匹配") | [Go](https://github.com/openset/leetcode/tree/master/problems/di-string-match) | Easy |
+| <span id="941">941</span> | [Valid Mountain Array](https://leetcode.com/problems/valid-mountain-array "有效的山脉数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-mountain-array) | Easy |
+| <span id="940">940</span> | [Distinct Subsequences II](https://leetcode.com/problems/distinct-subsequences-ii "不同的子序列 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/distinct-subsequences-ii) | Hard |
+| <span id="939">939</span> | [Minimum Area Rectangle](https://leetcode.com/problems/minimum-area-rectangle "最小面积矩形") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-area-rectangle) | Medium |
+| <span id="938">938</span> | [Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst "二叉搜索树的范围和") | [Go](https://github.com/openset/leetcode/tree/master/problems/range-sum-of-bst) | Medium |
+| <span id="937">937</span> | [Reorder Log Files](https://leetcode.com/problems/reorder-log-files "重新排列日志文件") | [Go](https://github.com/openset/leetcode/tree/master/problems/reorder-log-files) | Easy |
+| <span id="936">936</span> | [Stamping The Sequence](https://leetcode.com/problems/stamping-the-sequence "戳印序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/stamping-the-sequence) | Hard |
+| <span id="935">935</span> | [Knight Dialer](https://leetcode.com/problems/knight-dialer "骑士拨号器") | [Go](https://github.com/openset/leetcode/tree/master/problems/knight-dialer) | Medium |
+| <span id="934">934</span> | [Shortest Bridge](https://leetcode.com/problems/shortest-bridge "最短的桥") | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-bridge) | Medium |
+| <span id="933">933</span> | [Number of Recent Calls](https://leetcode.com/problems/number-of-recent-calls "最近的请求次数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-recent-calls) | Easy |
+| <span id="932">932</span> | [Beautiful Array](https://leetcode.com/problems/beautiful-array "漂亮数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/beautiful-array) | Medium |
+| <span id="931">931</span> | [Minimum Falling Path Sum](https://leetcode.com/problems/minimum-falling-path-sum "下降路径最小和") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-falling-path-sum) | Medium |
+| <span id="930">930</span> | [Binary Subarrays With Sum](https://leetcode.com/problems/binary-subarrays-with-sum "和相同的二元子数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-subarrays-with-sum) | Medium |
+| <span id="929">929</span> | [Unique Email Addresses](https://leetcode.com/problems/unique-email-addresses "独特的电子邮件地址") | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-email-addresses) | Easy |
+| <span id="928">928</span> | [Minimize Malware Spread II](https://leetcode.com/problems/minimize-malware-spread-ii "尽量减少恶意软件的传播 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimize-malware-spread-ii) | Hard |
+| <span id="927">927</span> | [Three Equal Parts](https://leetcode.com/problems/three-equal-parts "三等分") | [Go](https://github.com/openset/leetcode/tree/master/problems/three-equal-parts) | Hard |
+| <span id="926">926</span> | [Flip String to Monotone Increasing](https://leetcode.com/problems/flip-string-to-monotone-increasing "将字符串翻转到单调递增") | [Go](https://github.com/openset/leetcode/tree/master/problems/flip-string-to-monotone-increasing) | Medium |
+| <span id="925">925</span> | [Long Pressed Name](https://leetcode.com/problems/long-pressed-name "长按键入") | [Go](https://github.com/openset/leetcode/tree/master/problems/long-pressed-name) | Easy |
+| <span id="924">924</span> | [Minimize Malware Spread](https://leetcode.com/problems/minimize-malware-spread "尽量减少恶意软件的传播") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimize-malware-spread) | Hard |
+| <span id="923">923</span> | [3Sum With Multiplicity](https://leetcode.com/problems/3sum-with-multiplicity "三数之和的多种可能") | [Go](https://github.com/openset/leetcode/tree/master/problems/3sum-with-multiplicity) | Medium |
+| <span id="922">922</span> | [Sort Array By Parity II](https://leetcode.com/problems/sort-array-by-parity-ii "按奇偶排序数组 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/sort-array-by-parity-ii) | Easy |
+| <span id="921">921</span> | [Minimum Add to Make Parentheses Valid](https://leetcode.com/problems/minimum-add-to-make-parentheses-valid "使括号有效的最少添加") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-add-to-make-parentheses-valid) | Medium |
+| <span id="920">920</span> | [Number of Music Playlists](https://leetcode.com/problems/number-of-music-playlists "播放列表的数量") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-music-playlists) | Hard |
+| <span id="919">919</span> | [Complete Binary Tree Inserter](https://leetcode.com/problems/complete-binary-tree-inserter "完全二叉树插入器") | [Go](https://github.com/openset/leetcode/tree/master/problems/complete-binary-tree-inserter) | Medium |
+| <span id="918">918</span> | [Maximum Sum Circular Subarray](https://leetcode.com/problems/maximum-sum-circular-subarray "环形子数组的最大和") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-sum-circular-subarray) | Medium |
+| <span id="917">917</span> | [Reverse Only Letters](https://leetcode.com/problems/reverse-only-letters "仅仅反转字母") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-only-letters) | Easy |
+| <span id="916">916</span> | [Word Subsets](https://leetcode.com/problems/word-subsets "单词子集") | [Go](https://github.com/openset/leetcode/tree/master/problems/word-subsets) | Medium |
+| <span id="915">915</span> | [Partition Array into Disjoint Intervals](https://leetcode.com/problems/partition-array-into-disjoint-intervals "分割数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/partition-array-into-disjoint-intervals) | Medium |
+| <span id="914">914</span> | [X of a Kind in a Deck of Cards](https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards "卡牌分组") | [Go](https://github.com/openset/leetcode/tree/master/problems/x-of-a-kind-in-a-deck-of-cards) | Easy |
+| <span id="913">913</span> | [Cat and Mouse](https://leetcode.com/problems/cat-and-mouse "猫和老鼠") | [Go](https://github.com/openset/leetcode/tree/master/problems/cat-and-mouse) | Hard |
+| <span id="911">911</span> | [Online Election](https://leetcode.com/problems/online-election "在线选举") | [Go](https://github.com/openset/leetcode/tree/master/problems/online-election) | Medium |
+| <span id="910">910</span> | [Smallest Range II](https://leetcode.com/problems/smallest-range-ii "最小差值 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/smallest-range-ii) | Medium |
+| <span id="909">909</span> | [Snakes and Ladders](https://leetcode.com/problems/snakes-and-ladders "爬坡和梯子") | [Go](https://github.com/openset/leetcode/tree/master/problems/snakes-and-ladders) | Medium |
+| <span id="908">908</span> | [Smallest Range I](https://leetcode.com/problems/smallest-range-i "最小差值 I") | [Go](https://github.com/openset/leetcode/tree/master/problems/smallest-range-i) | Easy |
+| <span id="907">907</span> | [Sum of Subarray Minimums](https://leetcode.com/problems/sum-of-subarray-minimums "子数组的最小值之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/sum-of-subarray-minimums) | Medium |
+| <span id="906">906</span> | [Super Palindromes](https://leetcode.com/problems/super-palindromes "超级回文数") | [Go](https://github.com/openset/leetcode/tree/master/problems/super-palindromes) | Hard |
+| <span id="905">905</span> | [Sort Array By Parity](https://leetcode.com/problems/sort-array-by-parity "按奇偶排序数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/sort-array-by-parity) | Easy |
+| <span id="904">904</span> | [Fruit Into Baskets](https://leetcode.com/problems/fruit-into-baskets "水果成篮") | [Go](https://github.com/openset/leetcode/tree/master/problems/fruit-into-baskets) | Medium |
+| <span id="903">903</span> | [Valid Permutations for DI Sequence](https://leetcode.com/problems/valid-permutations-for-di-sequence "DI 序列的有效排列") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-permutations-for-di-sequence) | Hard |
+| <span id="902">902</span> | [Numbers At Most N Given Digit Set](https://leetcode.com/problems/numbers-at-most-n-given-digit-set "最大为 N 的数字组合") | [Go](https://github.com/openset/leetcode/tree/master/problems/numbers-at-most-n-given-digit-set) | Hard |
+| <span id="901">901</span> | [Online Stock Span](https://leetcode.com/problems/online-stock-span "股票价格跨度") | [Go](https://github.com/openset/leetcode/tree/master/problems/online-stock-span) | Medium |
+| <span id="900">900</span> | [RLE Iterator](https://leetcode.com/problems/rle-iterator "RLE 迭代器") | [Go](https://github.com/openset/leetcode/tree/master/problems/rle-iterator) | Medium |
+| <span id="899">899</span> | [Orderly Queue](https://leetcode.com/problems/orderly-queue "有序队列") | [Go](https://github.com/openset/leetcode/tree/master/problems/orderly-queue) | Hard |
+| <span id="898">898</span> | [Bitwise ORs of Subarrays](https://leetcode.com/problems/bitwise-ors-of-subarrays "子数组按位或操作") | [Go](https://github.com/openset/leetcode/tree/master/problems/bitwise-ors-of-subarrays) | Medium |
+| <span id="897">897</span> | [Increasing Order Search Tree](https://leetcode.com/problems/increasing-order-search-tree "递增顺序查找树") | [Go](https://github.com/openset/leetcode/tree/master/problems/increasing-order-search-tree) | Easy |
+| <span id="896">896</span> | [Monotonic Array](https://leetcode.com/problems/monotonic-array "单调数列") | [Go](https://github.com/openset/leetcode/tree/master/problems/monotonic-array) | Easy |
+| <span id="895">895</span> | [Maximum Frequency Stack](https://leetcode.com/problems/maximum-frequency-stack "最大频率栈") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-frequency-stack) | Hard |
+| <span id="894">894</span> | [All Possible Full Binary Trees](https://leetcode.com/problems/all-possible-full-binary-trees "所有可能的满二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/all-possible-full-binary-trees) | Medium |
+| <span id="893">893</span> | [Groups of Special-Equivalent Strings](https://leetcode.com/problems/groups-of-special-equivalent-strings "特殊等价字符串组") | [Go](https://github.com/openset/leetcode/tree/master/problems/groups-of-special-equivalent-strings) | Easy |
+| <span id="892">892</span> | [Surface Area of 3D Shapes](https://leetcode.com/problems/surface-area-of-3d-shapes "三维形体的表面积") | [Go](https://github.com/openset/leetcode/tree/master/problems/surface-area-of-3d-shapes) | Easy |
+| <span id="891">891</span> | [Sum of Subsequence Widths](https://leetcode.com/problems/sum-of-subsequence-widths "子序列宽度之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/sum-of-subsequence-widths) | Hard |
+| <span id="890">890</span> | [Find and Replace Pattern](https://leetcode.com/problems/find-and-replace-pattern "查找和替换模式") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-and-replace-pattern) | Medium |
+| <span id="889">889</span> | [Construct Binary Tree from Preorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-postorder-traversal "根据前序和后序遍历构造二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/construct-binary-tree-from-preorder-and-postorder-traversal) | Medium |
+| <span id="888">888</span> | [Fair Candy Swap](https://leetcode.com/problems/fair-candy-swap "公平的糖果交换") | [Go](https://github.com/openset/leetcode/tree/master/problems/fair-candy-swap) | Easy |
+| <span id="887">887</span> | [Super Egg Drop](https://leetcode.com/problems/super-egg-drop "鸡蛋掉落") | [Go](https://github.com/openset/leetcode/tree/master/problems/super-egg-drop) | Hard |
+| <span id="886">886</span> | [Possible Bipartition](https://leetcode.com/problems/possible-bipartition "可能的二分法") | [Go](https://github.com/openset/leetcode/tree/master/problems/possible-bipartition) | Medium |
+| <span id="885">885</span> | [Spiral Matrix III](https://leetcode.com/problems/spiral-matrix-iii "螺旋矩阵 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/spiral-matrix-iii) | Medium |
+| <span id="884">884</span> | [Uncommon Words from Two Sentences](https://leetcode.com/problems/uncommon-words-from-two-sentences "两句话中的不常见单词") | [Go](https://github.com/openset/leetcode/tree/master/problems/uncommon-words-from-two-sentences) | Easy |
+| <span id="883">883</span> | [Projection Area of 3D Shapes](https://leetcode.com/problems/projection-area-of-3d-shapes "三维形体投影面积") | [Go](https://github.com/openset/leetcode/tree/master/problems/projection-area-of-3d-shapes) | Easy |
+| <span id="882">882</span> | [Reachable Nodes In Subdivided Graph](https://leetcode.com/problems/reachable-nodes-in-subdivided-graph "细分图中的可到达结点") | [Go](https://github.com/openset/leetcode/tree/master/problems/reachable-nodes-in-subdivided-graph) | Hard |
+| <span id="881">881</span> | [Boats to Save People](https://leetcode.com/problems/boats-to-save-people "救生艇") | [Go](https://github.com/openset/leetcode/tree/master/problems/boats-to-save-people) | Medium |
+| <span id="880">880</span> | [Decoded String at Index](https://leetcode.com/problems/decoded-string-at-index "索引处的解码字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/decoded-string-at-index) | Medium |
+| <span id="879">879</span> | [Profitable Schemes](https://leetcode.com/problems/profitable-schemes "盈利计划") | [Go](https://github.com/openset/leetcode/tree/master/problems/profitable-schemes) | Hard |
+| <span id="878">878</span> | [Nth Magical Number](https://leetcode.com/problems/nth-magical-number "第 N 个神奇数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/nth-magical-number) | Hard |
+| <span id="877">877</span> | [Stone Game](https://leetcode.com/problems/stone-game "石子游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/stone-game) | Medium |
+| <span id="876">876</span> | [Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list "链表的中间结点") | [Go](https://github.com/openset/leetcode/tree/master/problems/middle-of-the-linked-list) | Easy |
+| <span id="875">875</span> | [Koko Eating Bananas](https://leetcode.com/problems/koko-eating-bananas "爱吃香蕉的珂珂") | [Go](https://github.com/openset/leetcode/tree/master/problems/koko-eating-bananas) | Medium |
+| <span id="874">874</span> | [Walking Robot Simulation](https://leetcode.com/problems/walking-robot-simulation "模拟行走机器人") | [Go](https://github.com/openset/leetcode/tree/master/problems/walking-robot-simulation) | Easy |
+| <span id="873">873</span> | [Length of Longest Fibonacci Subsequence](https://leetcode.com/problems/length-of-longest-fibonacci-subsequence "最长的斐波那契子序列的长度") | [Go](https://github.com/openset/leetcode/tree/master/problems/length-of-longest-fibonacci-subsequence) | Medium |
+| <span id="872">872</span> | [Leaf-Similar Trees](https://leetcode.com/problems/leaf-similar-trees "叶子相似的树") | [Go](https://github.com/openset/leetcode/tree/master/problems/leaf-similar-trees) | Easy |
+| <span id="871">871</span> | [Minimum Number of Refueling Stops](https://leetcode.com/problems/minimum-number-of-refueling-stops "最低加油次数") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-number-of-refueling-stops) | Hard |
+| <span id="870">870</span> | [Advantage Shuffle](https://leetcode.com/problems/advantage-shuffle "优势洗牌") | [Go](https://github.com/openset/leetcode/tree/master/problems/advantage-shuffle) | Medium |
+| <span id="869">869</span> | [Reordered Power of 2](https://leetcode.com/problems/reordered-power-of-2 "重新排序得到 2 的幂") | [Go](https://github.com/openset/leetcode/tree/master/problems/reordered-power-of-2) | Medium |
+| <span id="868">868</span> | [Binary Gap](https://leetcode.com/problems/binary-gap "二进制间距") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-gap) | Easy |
+| <span id="867">867</span> | [Transpose Matrix](https://leetcode.com/problems/transpose-matrix "转置矩阵") | [Go](https://github.com/openset/leetcode/tree/master/problems/transpose-matrix) | Easy |
+| <span id="866">866</span> | [Prime Palindrome](https://leetcode.com/problems/prime-palindrome "回文素数") | [Go](https://github.com/openset/leetcode/tree/master/problems/prime-palindrome) | Medium |
+| <span id="865">865</span> | [Smallest Subtree with all the Deepest Nodes](https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes "具有所有最深结点的最小子树") | [Go](https://github.com/openset/leetcode/tree/master/problems/smallest-subtree-with-all-the-deepest-nodes) | Medium |
+| <span id="864">864</span> | [Shortest Path to Get All Keys](https://leetcode.com/problems/shortest-path-to-get-all-keys "获取所有钥匙的最短路径") | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-path-to-get-all-keys) | Hard |
+| <span id="863">863</span> | [All Nodes Distance K in Binary Tree](https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree "二叉树中所有距离为 K 的结点") | [Go](https://github.com/openset/leetcode/tree/master/problems/all-nodes-distance-k-in-binary-tree) | Medium |
+| <span id="862">862</span> | [Shortest Subarray with Sum at Least K](https://leetcode.com/problems/shortest-subarray-with-sum-at-least-k "和至少为 K 的最短子数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-subarray-with-sum-at-least-k) | Hard |
+| <span id="861">861</span> | [Score After Flipping Matrix](https://leetcode.com/problems/score-after-flipping-matrix "翻转矩阵后的得分") | [Go](https://github.com/openset/leetcode/tree/master/problems/score-after-flipping-matrix) | Medium |
+| <span id="860">860</span> | [Lemonade Change](https://leetcode.com/problems/lemonade-change "柠檬水找零") | [Go](https://github.com/openset/leetcode/tree/master/problems/lemonade-change) | Easy |
+| <span id="859">859</span> | [Buddy Strings](https://leetcode.com/problems/buddy-strings "亲密字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/buddy-strings) | Easy |
+| <span id="858">858</span> | [Mirror Reflection](https://leetcode.com/problems/mirror-reflection "镜面反射") | [Go](https://github.com/openset/leetcode/tree/master/problems/mirror-reflection) | Medium |
+| <span id="857">857</span> | [Minimum Cost to Hire K Workers](https://leetcode.com/problems/minimum-cost-to-hire-k-workers "雇佣 K 名工人的最低成本") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-cost-to-hire-k-workers) | Hard |
+| <span id="856">856</span> | [Score of Parentheses](https://leetcode.com/problems/score-of-parentheses "括号的分数") | [Go](https://github.com/openset/leetcode/tree/master/problems/score-of-parentheses) | Medium |
+| <span id="855">855</span> | [Exam Room](https://leetcode.com/problems/exam-room "考场就座") | [Go](https://github.com/openset/leetcode/tree/master/problems/exam-room) | Medium |
+| <span id="854">854</span> | [K-Similar Strings](https://leetcode.com/problems/k-similar-strings "相似度为 K 的字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/k-similar-strings) | Hard |
+| <span id="853">853</span> | [Car Fleet](https://leetcode.com/problems/car-fleet "车队") | [Go](https://github.com/openset/leetcode/tree/master/problems/car-fleet) | Medium |
+| <span id="852">852</span> | [Peak Index in a Mountain Array](https://leetcode.com/problems/peak-index-in-a-mountain-array "山脉数组的峰顶索引") | [Go](https://github.com/openset/leetcode/tree/master/problems/peak-index-in-a-mountain-array) | Easy |
+| <span id="851">851</span> | [Loud and Rich](https://leetcode.com/problems/loud-and-rich "喧闹和富有") | [Go](https://github.com/openset/leetcode/tree/master/problems/loud-and-rich) | Medium |
+| <span id="850">850</span> | [Rectangle Area II](https://leetcode.com/problems/rectangle-area-ii "矩形面积 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/rectangle-area-ii) | Hard |
+| <span id="849">849</span> | [Maximize Distance to Closest Person](https://leetcode.com/problems/maximize-distance-to-closest-person "到最近的人的最大距离") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximize-distance-to-closest-person) | Easy |
+| <span id="848">848</span> | [Shifting Letters](https://leetcode.com/problems/shifting-letters "字母移位") | [Go](https://github.com/openset/leetcode/tree/master/problems/shifting-letters) | Medium |
+| <span id="847">847</span> | [Shortest Path Visiting All Nodes](https://leetcode.com/problems/shortest-path-visiting-all-nodes "访问所有节点的最短路径") | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-path-visiting-all-nodes) | Hard |
+| <span id="846">846</span> | [Hand of Straights](https://leetcode.com/problems/hand-of-straights "一手顺子") | [Go](https://github.com/openset/leetcode/tree/master/problems/hand-of-straights) | Medium |
+| <span id="845">845</span> | [Longest Mountain in Array](https://leetcode.com/problems/longest-mountain-in-array "数组中的最长山脉") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-mountain-in-array) | Medium |
+| <span id="844">844</span> | [Backspace String Compare](https://leetcode.com/problems/backspace-string-compare "比较含退格的字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/backspace-string-compare) | Easy |
+| <span id="843">843</span> | [Guess the Word](https://leetcode.com/problems/guess-the-word "猜猜这个单词") | [Go](https://github.com/openset/leetcode/tree/master/problems/guess-the-word) | Hard |
+| <span id="842">842</span> | [Split Array into Fibonacci Sequence](https://leetcode.com/problems/split-array-into-fibonacci-sequence "将数组拆分成斐波那契序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/split-array-into-fibonacci-sequence) | Medium |
+| <span id="841">841</span> | [Keys and Rooms](https://leetcode.com/problems/keys-and-rooms "钥匙和房间") | [Go](https://github.com/openset/leetcode/tree/master/problems/keys-and-rooms) | Medium |
+| <span id="840">840</span> | [Magic Squares In Grid](https://leetcode.com/problems/magic-squares-in-grid "矩阵中的幻方") | [Go](https://github.com/openset/leetcode/tree/master/problems/magic-squares-in-grid) | Easy |
+| <span id="839">839</span> | [Similar String Groups](https://leetcode.com/problems/similar-string-groups "相似字符串组") | [Go](https://github.com/openset/leetcode/tree/master/problems/similar-string-groups) | Hard |
+| <span id="838">838</span> | [Push Dominoes](https://leetcode.com/problems/push-dominoes "推多米诺") | [Go](https://github.com/openset/leetcode/tree/master/problems/push-dominoes) | Medium |
+| <span id="837">837</span> | [New 21 Game](https://leetcode.com/problems/new-21-game "新21点") | [Go](https://github.com/openset/leetcode/tree/master/problems/new-21-game) | Medium |
+| <span id="836">836</span> | [Rectangle Overlap](https://leetcode.com/problems/rectangle-overlap "矩形重叠") | [Go](https://github.com/openset/leetcode/tree/master/problems/rectangle-overlap) | Easy |
+| <span id="835">835</span> | [Image Overlap](https://leetcode.com/problems/image-overlap "图像重叠") | [Go](https://github.com/openset/leetcode/tree/master/problems/image-overlap) | Medium |
+| <span id="834">834</span> | [Sum of Distances in Tree](https://leetcode.com/problems/sum-of-distances-in-tree "树中距离之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/sum-of-distances-in-tree) | Hard |
+| <span id="833">833</span> | [Find And Replace in String](https://leetcode.com/problems/find-and-replace-in-string "字符串中的查找与替换") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-and-replace-in-string) | Medium |
+| <span id="832">832</span> | [Flipping an Image](https://leetcode.com/problems/flipping-an-image "翻转图像") | [Go](https://github.com/openset/leetcode/tree/master/problems/flipping-an-image) | Easy |
+| <span id="831">831</span> | [Masking Personal Information](https://leetcode.com/problems/masking-personal-information "隐藏个人信息") | [Go](https://github.com/openset/leetcode/tree/master/problems/masking-personal-information) | Medium |
+| <span id="830">830</span> | [Positions of Large Groups](https://leetcode.com/problems/positions-of-large-groups "较大分组的位置") | [Go](https://github.com/openset/leetcode/tree/master/problems/positions-of-large-groups) | Easy |
+| <span id="829">829</span> | [Consecutive Numbers Sum](https://leetcode.com/problems/consecutive-numbers-sum "连续整数求和") | [Go](https://github.com/openset/leetcode/tree/master/problems/consecutive-numbers-sum) | Hard |
+| <span id="828">828</span> | [Unique Letter String](https://leetcode.com/problems/unique-letter-string "独特字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-letter-string) | Hard |
+| <span id="827">827</span> | [Making A Large Island](https://leetcode.com/problems/making-a-large-island "最大人工岛") | [Go](https://github.com/openset/leetcode/tree/master/problems/making-a-large-island) | Hard |
+| <span id="826">826</span> | [Most Profit Assigning Work](https://leetcode.com/problems/most-profit-assigning-work "安排工作以达到最大收益") | [Go](https://github.com/openset/leetcode/tree/master/problems/most-profit-assigning-work) | Medium |
+| <span id="825">825</span> | [Friends Of Appropriate Ages](https://leetcode.com/problems/friends-of-appropriate-ages "适龄的朋友") | [Go](https://github.com/openset/leetcode/tree/master/problems/friends-of-appropriate-ages) | Medium |
+| <span id="824">824</span> | [Goat Latin](https://leetcode.com/problems/goat-latin "山羊拉丁文") | [Go](https://github.com/openset/leetcode/tree/master/problems/goat-latin) | Easy |
+| <span id="823">823</span> | [Binary Trees With Factors](https://leetcode.com/problems/binary-trees-with-factors "带因子的二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-trees-with-factors) | Medium |
+| <span id="822">822</span> | [Card Flipping Game](https://leetcode.com/problems/card-flipping-game "翻转卡片游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/card-flipping-game) | Medium |
+| <span id="821">821</span> | [Shortest Distance to a Character](https://leetcode.com/problems/shortest-distance-to-a-character "字符的最短距离") | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-distance-to-a-character) | Easy |
+| <span id="820">820</span> | [Short Encoding of Words](https://leetcode.com/problems/short-encoding-of-words "单词的压缩编码") | [Go](https://github.com/openset/leetcode/tree/master/problems/short-encoding-of-words) | Medium |
+| <span id="819">819</span> | [Most Common Word](https://leetcode.com/problems/most-common-word "最常见的单词") | [Go](https://github.com/openset/leetcode/tree/master/problems/most-common-word) | Easy |
+| <span id="818">818</span> | [Race Car](https://leetcode.com/problems/race-car "赛车") | [Go](https://github.com/openset/leetcode/tree/master/problems/race-car) | Hard |
+| <span id="817">817</span> | [Linked List Components](https://leetcode.com/problems/linked-list-components "链表组件") | [Go](https://github.com/openset/leetcode/tree/master/problems/linked-list-components) | Medium |
+| <span id="816">816</span> | [Ambiguous Coordinates](https://leetcode.com/problems/ambiguous-coordinates "模糊坐标") | [Go](https://github.com/openset/leetcode/tree/master/problems/ambiguous-coordinates) | Medium |
+| <span id="815">815</span> | [Bus Routes](https://leetcode.com/problems/bus-routes "公交路线") | [Go](https://github.com/openset/leetcode/tree/master/problems/bus-routes) | Hard |
+| <span id="814">814</span> | [Binary Tree Pruning](https://leetcode.com/problems/binary-tree-pruning "二叉树剪枝") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-pruning) | Medium |
+| <span id="813">813</span> | [Largest Sum of Averages](https://leetcode.com/problems/largest-sum-of-averages "最大平均值和的分组") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-sum-of-averages) | Medium |
+| <span id="812">812</span> | [Largest Triangle Area](https://leetcode.com/problems/largest-triangle-area "最大三角形面积") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-triangle-area) | Easy |
+| <span id="811">811</span> | [Subdomain Visit Count](https://leetcode.com/problems/subdomain-visit-count "子域名访问计数") | [Go](https://github.com/openset/leetcode/tree/master/problems/subdomain-visit-count) | Easy |
+| <span id="810">810</span> | [Chalkboard XOR Game](https://leetcode.com/problems/chalkboard-xor-game "黑板异或游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/chalkboard-xor-game) | Hard |
+| <span id="809">809</span> | [Expressive Words](https://leetcode.com/problems/expressive-words "情感丰富的文字") | [Go](https://github.com/openset/leetcode/tree/master/problems/expressive-words) | Medium |
+| <span id="808">808</span> | [Soup Servings](https://leetcode.com/problems/soup-servings "分汤") | [Go](https://github.com/openset/leetcode/tree/master/problems/soup-servings) | Medium |
+| <span id="807">807</span> | [Max Increase to Keep City Skyline](https://leetcode.com/problems/max-increase-to-keep-city-skyline "保持城市天际线") | [Go](https://github.com/openset/leetcode/tree/master/problems/max-increase-to-keep-city-skyline) | Medium |
+| <span id="806">806</span> | [Number of Lines To Write String](https://leetcode.com/problems/number-of-lines-to-write-string "写字符串需要的行数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-lines-to-write-string) | Easy |
+| <span id="805">805</span> | [Split Array With Same Average](https://leetcode.com/problems/split-array-with-same-average "数组的均值分割") | [Go](https://github.com/openset/leetcode/tree/master/problems/split-array-with-same-average) | Hard |
+| <span id="804">804</span> | [Unique Morse Code Words](https://leetcode.com/problems/unique-morse-code-words "唯一摩尔斯密码词") | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-morse-code-words) | Easy |
+| <span id="803">803</span> | [Bricks Falling When Hit](https://leetcode.com/problems/bricks-falling-when-hit "打砖块") | [Go](https://github.com/openset/leetcode/tree/master/problems/bricks-falling-when-hit) | Hard |
+| <span id="802">802</span> | [Find Eventual Safe States](https://leetcode.com/problems/find-eventual-safe-states "找到最终的安全状态") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-eventual-safe-states) | Medium |
+| <span id="801">801</span> | [Minimum Swaps To Make Sequences Increasing](https://leetcode.com/problems/minimum-swaps-to-make-sequences-increasing "使序列递增的最小交换次数") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-swaps-to-make-sequences-increasing) | Medium |
+| <span id="800">800</span> | [Similar RGB Color](https://leetcode.com/problems/similar-rgb-color) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/similar-rgb-color) | Easy |
+| <span id="799">799</span> | [Champagne Tower](https://leetcode.com/problems/champagne-tower "香槟塔") | [Go](https://github.com/openset/leetcode/tree/master/problems/champagne-tower) | Medium |
+| <span id="798">798</span> | [Smallest Rotation with Highest Score](https://leetcode.com/problems/smallest-rotation-with-highest-score "得分最高的最小轮调") | [Go](https://github.com/openset/leetcode/tree/master/problems/smallest-rotation-with-highest-score) | Hard |
+| <span id="797">797</span> | [All Paths From Source to Target](https://leetcode.com/problems/all-paths-from-source-to-target "所有可能的路径") | [Go](https://github.com/openset/leetcode/tree/master/problems/all-paths-from-source-to-target) | Medium |
+| <span id="796">796</span> | [Rotate String](https://leetcode.com/problems/rotate-string "旋转字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/rotate-string) | Easy |
+| <span id="795">795</span> | [Number of Subarrays with Bounded Maximum](https://leetcode.com/problems/number-of-subarrays-with-bounded-maximum "区间子数组个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-subarrays-with-bounded-maximum) | Medium |
+| <span id="794">794</span> | [Valid Tic-Tac-Toe State](https://leetcode.com/problems/valid-tic-tac-toe-state "有效的井字游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-tic-tac-toe-state) | Medium |
+| <span id="793">793</span> | [Preimage Size of Factorial Zeroes Function](https://leetcode.com/problems/preimage-size-of-factorial-zeroes-function "阶乘函数后K个零") | [Go](https://github.com/openset/leetcode/tree/master/problems/preimage-size-of-factorial-zeroes-function) | Hard |
+| <span id="792">792</span> | [Number of Matching Subsequences](https://leetcode.com/problems/number-of-matching-subsequences "匹配子序列的单词数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-matching-subsequences) | Medium |
+| <span id="791">791</span> | [Custom Sort String](https://leetcode.com/problems/custom-sort-string "自定义字符串排序") | [Go](https://github.com/openset/leetcode/tree/master/problems/custom-sort-string) | Medium |
+| <span id="790">790</span> | [Domino and Tromino Tiling](https://leetcode.com/problems/domino-and-tromino-tiling "多米诺和托米诺平铺") | [Go](https://github.com/openset/leetcode/tree/master/problems/domino-and-tromino-tiling) | Medium |
+| <span id="789">789</span> | [Escape The Ghosts](https://leetcode.com/problems/escape-the-ghosts "逃脱阻碍者") | [Go](https://github.com/openset/leetcode/tree/master/problems/escape-the-ghosts) | Medium |
+| <span id="788">788</span> | [Rotated Digits](https://leetcode.com/problems/rotated-digits "旋转数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/rotated-digits) | Easy |
+| <span id="787">787</span> | [Cheapest Flights Within K Stops](https://leetcode.com/problems/cheapest-flights-within-k-stops "K 站中转内最便宜的航班") | [Go](https://github.com/openset/leetcode/tree/master/problems/cheapest-flights-within-k-stops) | Medium |
+| <span id="786">786</span> | [K-th Smallest Prime Fraction](https://leetcode.com/problems/k-th-smallest-prime-fraction "第 K 个最小的素数分数") | [Go](https://github.com/openset/leetcode/tree/master/problems/k-th-smallest-prime-fraction) | Hard |
+| <span id="785">785</span> | [Is Graph Bipartite?](https://leetcode.com/problems/is-graph-bipartite "判断二分图") | [Go](https://github.com/openset/leetcode/tree/master/problems/is-graph-bipartite) | Medium |
+| <span id="784">784</span> | [Letter Case Permutation](https://leetcode.com/problems/letter-case-permutation "字母大小写全排列") | [Go](https://github.com/openset/leetcode/tree/master/problems/letter-case-permutation) | Easy |
+| <span id="783">783</span> | [Minimum Distance Between BST Nodes](https://leetcode.com/problems/minimum-distance-between-bst-nodes "二叉搜索树结点最小距离") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-distance-between-bst-nodes) | Easy |
+| <span id="782">782</span> | [Transform to Chessboard](https://leetcode.com/problems/transform-to-chessboard "变为棋盘") | [Go](https://github.com/openset/leetcode/tree/master/problems/transform-to-chessboard) | Hard |
+| <span id="781">781</span> | [Rabbits in Forest](https://leetcode.com/problems/rabbits-in-forest "森林中的兔子") | [Go](https://github.com/openset/leetcode/tree/master/problems/rabbits-in-forest) | Medium |
+| <span id="780">780</span> | [Reaching Points](https://leetcode.com/problems/reaching-points "到达终点") | [Go](https://github.com/openset/leetcode/tree/master/problems/reaching-points) | Hard |
+| <span id="779">779</span> | [K-th Symbol in Grammar](https://leetcode.com/problems/k-th-symbol-in-grammar "第K个语法符号") | [Go](https://github.com/openset/leetcode/tree/master/problems/k-th-symbol-in-grammar) | Medium |
+| <span id="778">778</span> | [Swim in Rising Water](https://leetcode.com/problems/swim-in-rising-water "水位上升的泳池中游泳") | [Go](https://github.com/openset/leetcode/tree/master/problems/swim-in-rising-water) | Hard |
+| <span id="777">777</span> | [Swap Adjacent in LR String](https://leetcode.com/problems/swap-adjacent-in-lr-string "在LR字符串中交换相邻字符") | [Go](https://github.com/openset/leetcode/tree/master/problems/swap-adjacent-in-lr-string) | Medium |
+| <span id="776">776</span> | [Split BST](https://leetcode.com/problems/split-bst) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/split-bst) | Medium |
+| <span id="775">775</span> | [Global and Local Inversions](https://leetcode.com/problems/global-and-local-inversions "全局倒置与局部倒置") | [Go](https://github.com/openset/leetcode/tree/master/problems/global-and-local-inversions) | Medium |
+| <span id="774">774</span> | [Minimize Max Distance to Gas Station](https://leetcode.com/problems/minimize-max-distance-to-gas-station) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/minimize-max-distance-to-gas-station) | Hard |
+| <span id="773">773</span> | [Sliding Puzzle](https://leetcode.com/problems/sliding-puzzle "滑动谜题") | [Go](https://github.com/openset/leetcode/tree/master/problems/sliding-puzzle) | Hard |
+| <span id="772">772</span> | [Basic Calculator III](https://leetcode.com/problems/basic-calculator-iii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/basic-calculator-iii) | Hard |
+| <span id="771">771</span> | [Jewels and Stones](https://leetcode.com/problems/jewels-and-stones "宝石与石头") | [Go](https://github.com/openset/leetcode/tree/master/problems/jewels-and-stones) | Easy |
+| <span id="770">770</span> | [Basic Calculator IV](https://leetcode.com/problems/basic-calculator-iv "基本计算器 IV") | [Go](https://github.com/openset/leetcode/tree/master/problems/basic-calculator-iv) | Hard |
+| <span id="769">769</span> | [Max Chunks To Make Sorted](https://leetcode.com/problems/max-chunks-to-make-sorted "最多能完成排序的块") | [Go](https://github.com/openset/leetcode/tree/master/problems/max-chunks-to-make-sorted) | Medium |
+| <span id="768">768</span> | [Max Chunks To Make Sorted II](https://leetcode.com/problems/max-chunks-to-make-sorted-ii "最多能完成排序的块 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/max-chunks-to-make-sorted-ii) | Hard |
+| <span id="767">767</span> | [Reorganize String](https://leetcode.com/problems/reorganize-string "重构字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/reorganize-string) | Medium |
+| <span id="766">766</span> | [Toeplitz Matrix](https://leetcode.com/problems/toeplitz-matrix "托普利茨矩阵") | [Go](https://github.com/openset/leetcode/tree/master/problems/toeplitz-matrix) | Easy |
+| <span id="765">765</span> | [Couples Holding Hands](https://leetcode.com/problems/couples-holding-hands "情侣牵手") | [Go](https://github.com/openset/leetcode/tree/master/problems/couples-holding-hands) | Hard |
+| <span id="764">764</span> | [Largest Plus Sign](https://leetcode.com/problems/largest-plus-sign "最大加号标志") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-plus-sign) | Medium |
+| <span id="763">763</span> | [Partition Labels](https://leetcode.com/problems/partition-labels "划分字母区间") | [Go](https://github.com/openset/leetcode/tree/master/problems/partition-labels) | Medium |
+| <span id="762">762</span> | [Prime Number of Set Bits in Binary Representation](https://leetcode.com/problems/prime-number-of-set-bits-in-binary-representation "二进制表示中质数个计算置位") | [Go](https://github.com/openset/leetcode/tree/master/problems/prime-number-of-set-bits-in-binary-representation) | Easy |
+| <span id="761">761</span> | [Special Binary String](https://leetcode.com/problems/special-binary-string "特殊的二进制序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/special-binary-string) | Hard |
+| <span id="760">760</span> | [Find Anagram Mappings](https://leetcode.com/problems/find-anagram-mappings) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/find-anagram-mappings) | Easy |
+| <span id="759">759</span> | [Employee Free Time](https://leetcode.com/problems/employee-free-time) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/employee-free-time) | Hard |
+| <span id="758">758</span> | [Bold Words in String](https://leetcode.com/problems/bold-words-in-string) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/bold-words-in-string) | Easy |
+| <span id="757">757</span> | [Set Intersection Size At Least Two](https://leetcode.com/problems/set-intersection-size-at-least-two " 设置交集大小至少为2") | [Go](https://github.com/openset/leetcode/tree/master/problems/set-intersection-size-at-least-two) | Hard |
+| <span id="756">756</span> | [Pyramid Transition Matrix](https://leetcode.com/problems/pyramid-transition-matrix "金字塔转换矩阵") | [Go](https://github.com/openset/leetcode/tree/master/problems/pyramid-transition-matrix) | Medium |
+| <span id="755">755</span> | [Pour Water](https://leetcode.com/problems/pour-water) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/pour-water) | Medium |
+| <span id="754">754</span> | [Reach a Number](https://leetcode.com/problems/reach-a-number "到达终点数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/reach-a-number) | Easy |
+| <span id="753">753</span> | [Cracking the Safe](https://leetcode.com/problems/cracking-the-safe "破解保险箱") | [Go](https://github.com/openset/leetcode/tree/master/problems/cracking-the-safe) | Hard |
+| <span id="752">752</span> | [Open the Lock](https://leetcode.com/problems/open-the-lock "打开转盘锁") | [Go](https://github.com/openset/leetcode/tree/master/problems/open-the-lock) | Medium |
+| <span id="751">751</span> | [IP to CIDR](https://leetcode.com/problems/ip-to-cidr) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/ip-to-cidr) | Easy |
+| <span id="750">750</span> | [Number Of Corner Rectangles](https://leetcode.com/problems/number-of-corner-rectangles) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-corner-rectangles) | Medium |
+| <span id="749">749</span> | [Contain Virus](https://leetcode.com/problems/contain-virus "隔离病毒") | [Go](https://github.com/openset/leetcode/tree/master/problems/contain-virus) | Hard |
+| <span id="748">748</span> | [Shortest Completing Word](https://leetcode.com/problems/shortest-completing-word "最短完整词") | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-completing-word) | Easy |
+| <span id="747">747</span> | [Largest Number At Least Twice of Others](https://leetcode.com/problems/largest-number-at-least-twice-of-others "至少是其他数字两倍的最大数") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-number-at-least-twice-of-others) | Easy |
+| <span id="746">746</span> | [Min Cost Climbing Stairs](https://leetcode.com/problems/min-cost-climbing-stairs "使用最小花费爬楼梯") | [Go](https://github.com/openset/leetcode/tree/master/problems/min-cost-climbing-stairs) | Easy |
+| <span id="745">745</span> | [Prefix and Suffix Search](https://leetcode.com/problems/prefix-and-suffix-search "前缀和后缀搜索") | [Go](https://github.com/openset/leetcode/tree/master/problems/prefix-and-suffix-search) | Hard |
+| <span id="744">744</span> | [Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target "寻找比目标字母大的最小字母") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-smallest-letter-greater-than-target) | Easy |
+| <span id="743">743</span> | [Network Delay Time](https://leetcode.com/problems/network-delay-time "网络延迟时间") | [Go](https://github.com/openset/leetcode/tree/master/problems/network-delay-time) | Easy |
+| <span id="742">742</span> | [Closest Leaf in a Binary Tree](https://leetcode.com/problems/closest-leaf-in-a-binary-tree) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/closest-leaf-in-a-binary-tree) | Medium |
+| <span id="741">741</span> | [Cherry Pickup](https://leetcode.com/problems/cherry-pickup "摘樱桃") | [Go](https://github.com/openset/leetcode/tree/master/problems/cherry-pickup) | Hard |
+| <span id="740">740</span> | [Delete and Earn](https://leetcode.com/problems/delete-and-earn "删除与获得点数") | [Go](https://github.com/openset/leetcode/tree/master/problems/delete-and-earn) | Medium |
+| <span id="739">739</span> | [Daily Temperatures](https://leetcode.com/problems/daily-temperatures "每日温度") | [Go](https://github.com/openset/leetcode/tree/master/problems/daily-temperatures) | Medium |
+| <span id="738">738</span> | [Monotone Increasing Digits](https://leetcode.com/problems/monotone-increasing-digits "单调递增的数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/monotone-increasing-digits) | Medium |
+| <span id="737">737</span> | [Sentence Similarity II](https://leetcode.com/problems/sentence-similarity-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/sentence-similarity-ii) | Medium |
+| <span id="736">736</span> | [Parse Lisp Expression](https://leetcode.com/problems/parse-lisp-expression "Lisp 语法解析") | [Go](https://github.com/openset/leetcode/tree/master/problems/parse-lisp-expression) | Hard |
+| <span id="735">735</span> | [Asteroid Collision](https://leetcode.com/problems/asteroid-collision "行星碰撞") | [Go](https://github.com/openset/leetcode/tree/master/problems/asteroid-collision) | Medium |
+| <span id="734">734</span> | [Sentence Similarity](https://leetcode.com/problems/sentence-similarity) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/sentence-similarity) | Easy |
+| <span id="733">733</span> | [Flood Fill](https://leetcode.com/problems/flood-fill "图像渲染") | [Go](https://github.com/openset/leetcode/tree/master/problems/flood-fill) | Easy |
+| <span id="732">732</span> | [My Calendar III](https://leetcode.com/problems/my-calendar-iii "我的日程安排表 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/my-calendar-iii) | Hard |
+| <span id="731">731</span> | [My Calendar II](https://leetcode.com/problems/my-calendar-ii "我的日程安排表 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/my-calendar-ii) | Medium |
+| <span id="730">730</span> | [Count Different Palindromic Subsequences](https://leetcode.com/problems/count-different-palindromic-subsequences "统计不同回文子字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-different-palindromic-subsequences) | Hard |
+| <span id="729">729</span> | [My Calendar I](https://leetcode.com/problems/my-calendar-i "我的日程安排表 I") | [Go](https://github.com/openset/leetcode/tree/master/problems/my-calendar-i) | Medium |
+| <span id="728">728</span> | [Self Dividing Numbers](https://leetcode.com/problems/self-dividing-numbers "自除数") | [Go](https://github.com/openset/leetcode/tree/master/problems/self-dividing-numbers) | Easy |
+| <span id="727">727</span> | [Minimum Window Subsequence](https://leetcode.com/problems/minimum-window-subsequence) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-window-subsequence) | Hard |
+| <span id="726">726</span> | [Number of Atoms](https://leetcode.com/problems/number-of-atoms "原子的数量") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-atoms) | Hard |
+| <span id="725">725</span> | [Split Linked List in Parts](https://leetcode.com/problems/split-linked-list-in-parts "分隔链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/split-linked-list-in-parts) | Medium |
+| <span id="724">724</span> | [Find Pivot Index](https://leetcode.com/problems/find-pivot-index "寻找数组的中心索引") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-pivot-index) | Easy |
+| <span id="723">723</span> | [Candy Crush](https://leetcode.com/problems/candy-crush) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/candy-crush) | Medium |
+| <span id="722">722</span> | [Remove Comments](https://leetcode.com/problems/remove-comments "删除注释") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-comments) | Medium |
+| <span id="721">721</span> | [Accounts Merge](https://leetcode.com/problems/accounts-merge "账户合并") | [Go](https://github.com/openset/leetcode/tree/master/problems/accounts-merge) | Medium |
+| <span id="720">720</span> | [Longest Word in Dictionary](https://leetcode.com/problems/longest-word-in-dictionary "词典中最长的单词") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-word-in-dictionary) | Easy |
+| <span id="719">719</span> | [Find K-th Smallest Pair Distance](https://leetcode.com/problems/find-k-th-smallest-pair-distance "找出第 k 小的距离对") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-k-th-smallest-pair-distance) | Hard |
+| <span id="718">718</span> | [Maximum Length of Repeated Subarray](https://leetcode.com/problems/maximum-length-of-repeated-subarray "最长重复子数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-length-of-repeated-subarray) | Medium |
+| <span id="717">717</span> | [1-bit and 2-bit Characters](https://leetcode.com/problems/1-bit-and-2-bit-characters "1比特与2比特字符") | [Go](https://github.com/openset/leetcode/tree/master/problems/1-bit-and-2-bit-characters) | Easy |
+| <span id="716">716</span> | [Max Stack](https://leetcode.com/problems/max-stack) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/max-stack) | Easy |
+| <span id="715">715</span> | [Range Module](https://leetcode.com/problems/range-module "Range 模块") | [Go](https://github.com/openset/leetcode/tree/master/problems/range-module) | Hard |
+| <span id="714">714</span> | [Best Time to Buy and Sell Stock with Transaction Fee](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-transaction-fee "买卖股票的最佳时机含手续费") | [Go](https://github.com/openset/leetcode/tree/master/problems/best-time-to-buy-and-sell-stock-with-transaction-fee) | Medium |
+| <span id="713">713</span> | [Subarray Product Less Than K](https://leetcode.com/problems/subarray-product-less-than-k "乘积小于K的子数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/subarray-product-less-than-k) | Medium |
+| <span id="712">712</span> | [Minimum ASCII Delete Sum for Two Strings](https://leetcode.com/problems/minimum-ascii-delete-sum-for-two-strings "两个字符串的最小ASCII删除和") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-ascii-delete-sum-for-two-strings) | Medium |
+| <span id="711">711</span> | [Number of Distinct Islands II](https://leetcode.com/problems/number-of-distinct-islands-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-distinct-islands-ii) | Hard |
+| <span id="710">710</span> | [Random Pick with Blacklist](https://leetcode.com/problems/random-pick-with-blacklist "黑名单中的随机数") | [Go](https://github.com/openset/leetcode/tree/master/problems/random-pick-with-blacklist) | Hard |
+| <span id="709">709</span> | [To Lower Case](https://leetcode.com/problems/to-lower-case "转换成小写字母") | [Go](https://github.com/openset/leetcode/tree/master/problems/to-lower-case) | Easy |
+| <span id="708">708</span> | [Insert into a Cyclic Sorted List](https://leetcode.com/problems/insert-into-a-cyclic-sorted-list) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/insert-into-a-cyclic-sorted-list) | Medium |
+| <span id="707">707</span> | [Design Linked List](https://leetcode.com/problems/design-linked-list "设计链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/design-linked-list) | Easy |
+| <span id="706">706</span> | [Design HashMap](https://leetcode.com/problems/design-hashmap "设计哈希映射") | [Go](https://github.com/openset/leetcode/tree/master/problems/design-hashmap) | Easy |
+| <span id="705">705</span> | [Design HashSet](https://leetcode.com/problems/design-hashset "设计哈希集合") | [Go](https://github.com/openset/leetcode/tree/master/problems/design-hashset) | Easy |
+| <span id="704">704</span> | [Binary Search](https://leetcode.com/problems/binary-search "二分查找") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-search) | Easy |
+| <span id="703">703</span> | [Kth Largest Element in a Stream](https://leetcode.com/problems/kth-largest-element-in-a-stream "数据流中的第K大元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/kth-largest-element-in-a-stream) | Easy |
+| <span id="702">702</span> | [Search in a Sorted Array of Unknown Size](https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/search-in-a-sorted-array-of-unknown-size) | Medium |
+| <span id="701">701</span> | [Insert into a Binary Search Tree](https://leetcode.com/problems/insert-into-a-binary-search-tree "二叉搜索树中的插入操作") | [Go](https://github.com/openset/leetcode/tree/master/problems/insert-into-a-binary-search-tree) | Medium |
+| <span id="700">700</span> | [Search in a Binary Search Tree](https://leetcode.com/problems/search-in-a-binary-search-tree "二叉搜索树中的搜索") | [Go](https://github.com/openset/leetcode/tree/master/problems/search-in-a-binary-search-tree) | Easy |
+| <span id="699">699</span> | [Falling Squares](https://leetcode.com/problems/falling-squares "掉落的方块") | [Go](https://github.com/openset/leetcode/tree/master/problems/falling-squares) | Hard |
+| <span id="698">698</span> | [Partition to K Equal Sum Subsets](https://leetcode.com/problems/partition-to-k-equal-sum-subsets "划分为k个相等的子集") | [Go](https://github.com/openset/leetcode/tree/master/problems/partition-to-k-equal-sum-subsets) | Medium |
+| <span id="697">697</span> | [Degree of an Array](https://leetcode.com/problems/degree-of-an-array "数组的度") | [Go](https://github.com/openset/leetcode/tree/master/problems/degree-of-an-array) | Easy |
+| <span id="696">696</span> | [Count Binary Substrings](https://leetcode.com/problems/count-binary-substrings "计数二进制子串") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-binary-substrings) | Easy |
+| <span id="695">695</span> | [Max Area of Island](https://leetcode.com/problems/max-area-of-island "岛屿的最大面积") | [Go](https://github.com/openset/leetcode/tree/master/problems/max-area-of-island) | Medium |
+| <span id="694">694</span> | [Number of Distinct Islands](https://leetcode.com/problems/number-of-distinct-islands) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-distinct-islands) | Medium |
+| <span id="693">693</span> | [Binary Number with Alternating Bits](https://leetcode.com/problems/binary-number-with-alternating-bits "交替位二进制数") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-number-with-alternating-bits) | Easy |
+| <span id="692">692</span> | [Top K Frequent Words](https://leetcode.com/problems/top-k-frequent-words "前K个高频单词") | [Go](https://github.com/openset/leetcode/tree/master/problems/top-k-frequent-words) | Medium |
+| <span id="691">691</span> | [Stickers to Spell Word](https://leetcode.com/problems/stickers-to-spell-word "贴纸拼词") | [Go](https://github.com/openset/leetcode/tree/master/problems/stickers-to-spell-word) | Hard |
+| <span id="690">690</span> | [Employee Importance](https://leetcode.com/problems/employee-importance "员工的重要性") | [Go](https://github.com/openset/leetcode/tree/master/problems/employee-importance) | Easy |
+| <span id="689">689</span> | [Maximum Sum of 3 Non-Overlapping Subarrays](https://leetcode.com/problems/maximum-sum-of-3-non-overlapping-subarrays "三个无重叠子数组的最大和") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-sum-of-3-non-overlapping-subarrays) | Hard |
+| <span id="688">688</span> | [Knight Probability in Chessboard](https://leetcode.com/problems/knight-probability-in-chessboard "“马”在棋盘上的概率") | [Go](https://github.com/openset/leetcode/tree/master/problems/knight-probability-in-chessboard) | Medium |
+| <span id="687">687</span> | [Longest Univalue Path](https://leetcode.com/problems/longest-univalue-path "最长同值路径") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-univalue-path) | Easy |
+| <span id="686">686</span> | [Repeated String Match](https://leetcode.com/problems/repeated-string-match "重复叠加字符串匹配") | [Go](https://github.com/openset/leetcode/tree/master/problems/repeated-string-match) | Easy |
+| <span id="685">685</span> | [Redundant Connection II](https://leetcode.com/problems/redundant-connection-ii "冗余连接 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/redundant-connection-ii) | Hard |
+| <span id="684">684</span> | [Redundant Connection](https://leetcode.com/problems/redundant-connection "冗余连接") | [Go](https://github.com/openset/leetcode/tree/master/problems/redundant-connection) | Medium |
+| <span id="683">683</span> | [K Empty Slots](https://leetcode.com/problems/k-empty-slots) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/k-empty-slots) | Hard |
+| <span id="682">682</span> | [Baseball Game](https://leetcode.com/problems/baseball-game "棒球比赛") | [Go](https://github.com/openset/leetcode/tree/master/problems/baseball-game) | Easy |
+| <span id="681">681</span> | [Next Closest Time](https://leetcode.com/problems/next-closest-time) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/next-closest-time) | Medium |
+| <span id="680">680</span> | [Valid Palindrome II](https://leetcode.com/problems/valid-palindrome-ii "验证回文字符串 Ⅱ") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-palindrome-ii) | Easy |
+| <span id="679">679</span> | [24 Game](https://leetcode.com/problems/24-game "24点游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/24-game) | Hard |
+| <span id="678">678</span> | [Valid Parenthesis String](https://leetcode.com/problems/valid-parenthesis-string "有效的括号字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-parenthesis-string) | Medium |
+| <span id="677">677</span> | [Map Sum Pairs](https://leetcode.com/problems/map-sum-pairs "键值映射") | [Go](https://github.com/openset/leetcode/tree/master/problems/map-sum-pairs) | Medium |
+| <span id="676">676</span> | [Implement Magic Dictionary](https://leetcode.com/problems/implement-magic-dictionary "实现一个魔法字典") | [Go](https://github.com/openset/leetcode/tree/master/problems/implement-magic-dictionary) | Medium |
+| <span id="675">675</span> | [Cut Off Trees for Golf Event](https://leetcode.com/problems/cut-off-trees-for-golf-event "为高尔夫比赛砍树") | [Go](https://github.com/openset/leetcode/tree/master/problems/cut-off-trees-for-golf-event) | Hard |
+| <span id="674">674</span> | [Longest Continuous Increasing Subsequence](https://leetcode.com/problems/longest-continuous-increasing-subsequence "最长连续递增序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-continuous-increasing-subsequence) | Easy |
+| <span id="673">673</span> | [Number of Longest Increasing Subsequence](https://leetcode.com/problems/number-of-longest-increasing-subsequence "最长递增子序列的个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-longest-increasing-subsequence) | Medium |
+| <span id="672">672</span> | [Bulb Switcher II](https://leetcode.com/problems/bulb-switcher-ii "灯泡开关 Ⅱ") | [Go](https://github.com/openset/leetcode/tree/master/problems/bulb-switcher-ii) | Medium |
+| <span id="671">671</span> | [Second Minimum Node In a Binary Tree](https://leetcode.com/problems/second-minimum-node-in-a-binary-tree "二叉树中第二小的节点") | [Go](https://github.com/openset/leetcode/tree/master/problems/second-minimum-node-in-a-binary-tree) | Easy |
+| <span id="670">670</span> | [Maximum Swap](https://leetcode.com/problems/maximum-swap "最大交换") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-swap) | Medium |
+| <span id="669">669</span> | [Trim a Binary Search Tree](https://leetcode.com/problems/trim-a-binary-search-tree "修剪二叉搜索树") | [Go](https://github.com/openset/leetcode/tree/master/problems/trim-a-binary-search-tree) | Easy |
+| <span id="668">668</span> | [Kth Smallest Number in Multiplication Table](https://leetcode.com/problems/kth-smallest-number-in-multiplication-table "乘法表中第k小的数") | [Go](https://github.com/openset/leetcode/tree/master/problems/kth-smallest-number-in-multiplication-table) | Hard |
+| <span id="667">667</span> | [Beautiful Arrangement II](https://leetcode.com/problems/beautiful-arrangement-ii "优美的排列 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/beautiful-arrangement-ii) | Medium |
+| <span id="666">666</span> | [Path Sum IV](https://leetcode.com/problems/path-sum-iv) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/path-sum-iv) | Medium |
+| <span id="665">665</span> | [Non-decreasing Array](https://leetcode.com/problems/non-decreasing-array "非递减数列") | [Go](https://github.com/openset/leetcode/tree/master/problems/non-decreasing-array) | Easy |
+| <span id="664">664</span> | [Strange Printer](https://leetcode.com/problems/strange-printer "奇怪的打印机") | [Go](https://github.com/openset/leetcode/tree/master/problems/strange-printer) | Hard |
+| <span id="663">663</span> | [Equal Tree Partition](https://leetcode.com/problems/equal-tree-partition) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/equal-tree-partition) | Medium |
+| <span id="662">662</span> | [Maximum Width of Binary Tree](https://leetcode.com/problems/maximum-width-of-binary-tree "二叉树最大宽度") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-width-of-binary-tree) | Medium |
+| <span id="661">661</span> | [Image Smoother](https://leetcode.com/problems/image-smoother "图片平滑器") | [Go](https://github.com/openset/leetcode/tree/master/problems/image-smoother) | Easy |
+| <span id="660">660</span> | [Remove 9](https://leetcode.com/problems/remove-9) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-9) | Hard |
+| <span id="659">659</span> | [Split Array into Consecutive Subsequences](https://leetcode.com/problems/split-array-into-consecutive-subsequences "分割数组为连续子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/split-array-into-consecutive-subsequences) | Medium |
+| <span id="658">658</span> | [Find K Closest Elements](https://leetcode.com/problems/find-k-closest-elements "找到 K 个最接近的元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-k-closest-elements) | Medium |
+| <span id="657">657</span> | [Robot Return to Origin](https://leetcode.com/problems/robot-return-to-origin "机器人能否返回原点") | [Go](https://github.com/openset/leetcode/tree/master/problems/robot-return-to-origin) | Easy |
+| <span id="656">656</span> | [Coin Path](https://leetcode.com/problems/coin-path) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/coin-path) | Hard |
+| <span id="655">655</span> | [Print Binary Tree](https://leetcode.com/problems/print-binary-tree "输出二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/print-binary-tree) | Medium |
+| <span id="654">654</span> | [Maximum Binary Tree](https://leetcode.com/problems/maximum-binary-tree "最大二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-binary-tree) | Medium |
+| <span id="653">653</span> | [Two Sum IV - Input is a BST](https://leetcode.com/problems/two-sum-iv-input-is-a-bst "两数之和 IV - 输入 BST") | [Go](https://github.com/openset/leetcode/tree/master/problems/two-sum-iv-input-is-a-bst) | Easy |
+| <span id="652">652</span> | [Find Duplicate Subtrees](https://leetcode.com/problems/find-duplicate-subtrees "寻找重复的子树") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-duplicate-subtrees) | Medium |
+| <span id="651">651</span> | [4 Keys Keyboard](https://leetcode.com/problems/4-keys-keyboard) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/4-keys-keyboard) | Medium |
+| <span id="650">650</span> | [2 Keys Keyboard](https://leetcode.com/problems/2-keys-keyboard "只有两个键的键盘") | [Go](https://github.com/openset/leetcode/tree/master/problems/2-keys-keyboard) | Medium |
+| <span id="649">649</span> | [Dota2 Senate](https://leetcode.com/problems/dota2-senate "Dota2 参议院") | [Go](https://github.com/openset/leetcode/tree/master/problems/dota2-senate) | Medium |
+| <span id="648">648</span> | [Replace Words](https://leetcode.com/problems/replace-words "单词替换") | [Go](https://github.com/openset/leetcode/tree/master/problems/replace-words) | Medium |
+| <span id="647">647</span> | [Palindromic Substrings](https://leetcode.com/problems/palindromic-substrings "回文子串") | [Go](https://github.com/openset/leetcode/tree/master/problems/palindromic-substrings) | Medium |
+| <span id="646">646</span> | [Maximum Length of Pair Chain](https://leetcode.com/problems/maximum-length-of-pair-chain "最长数对链") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-length-of-pair-chain) | Medium |
+| <span id="645">645</span> | [Set Mismatch](https://leetcode.com/problems/set-mismatch "错误的集合") | [Go](https://github.com/openset/leetcode/tree/master/problems/set-mismatch) | Easy |
+| <span id="644">644</span> | [Maximum Average Subarray II](https://leetcode.com/problems/maximum-average-subarray-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-average-subarray-ii) | Hard |
+| <span id="643">643</span> | [Maximum Average Subarray I](https://leetcode.com/problems/maximum-average-subarray-i "子数组最大平均数 I") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-average-subarray-i) | Easy |
+| <span id="642">642</span> | [Design Search Autocomplete System](https://leetcode.com/problems/design-search-autocomplete-system) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/design-search-autocomplete-system) | Hard |
+| <span id="641">641</span> | [Design Circular Deque](https://leetcode.com/problems/design-circular-deque "设计循环双端队列") | [Go](https://github.com/openset/leetcode/tree/master/problems/design-circular-deque) | Medium |
+| <span id="640">640</span> | [Solve the Equation](https://leetcode.com/problems/solve-the-equation "求解方程") | [Go](https://github.com/openset/leetcode/tree/master/problems/solve-the-equation) | Medium |
+| <span id="639">639</span> | [Decode Ways II](https://leetcode.com/problems/decode-ways-ii "解码方法 2") | [Go](https://github.com/openset/leetcode/tree/master/problems/decode-ways-ii) | Hard |
+| <span id="638">638</span> | [Shopping Offers](https://leetcode.com/problems/shopping-offers "大礼包") | [Go](https://github.com/openset/leetcode/tree/master/problems/shopping-offers) | Medium |
+| <span id="637">637</span> | [Average of Levels in Binary Tree](https://leetcode.com/problems/average-of-levels-in-binary-tree "二叉树的层平均值") | [Go](https://github.com/openset/leetcode/tree/master/problems/average-of-levels-in-binary-tree) | Easy |
+| <span id="636">636</span> | [Exclusive Time of Functions](https://leetcode.com/problems/exclusive-time-of-functions "函数的独占时间") | [Go](https://github.com/openset/leetcode/tree/master/problems/exclusive-time-of-functions) | Medium |
+| <span id="635">635</span> | [Design Log Storage System](https://leetcode.com/problems/design-log-storage-system) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/design-log-storage-system) | Medium |
+| <span id="634">634</span> | [Find the Derangement of An Array](https://leetcode.com/problems/find-the-derangement-of-an-array) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/find-the-derangement-of-an-array) | Medium |
+| <span id="633">633</span> | [Sum of Square Numbers](https://leetcode.com/problems/sum-of-square-numbers "平方数之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/sum-of-square-numbers) | Easy |
+| <span id="632">632</span> | [Smallest Range](https://leetcode.com/problems/smallest-range "最小区间") | [Go](https://github.com/openset/leetcode/tree/master/problems/smallest-range) | Hard |
+| <span id="631">631</span> | [Design Excel Sum Formula](https://leetcode.com/problems/design-excel-sum-formula) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/design-excel-sum-formula) | Hard |
+| <span id="630">630</span> | [Course Schedule III](https://leetcode.com/problems/course-schedule-iii "课程表 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/course-schedule-iii) | Hard |
+| <span id="629">629</span> | [K Inverse Pairs Array](https://leetcode.com/problems/k-inverse-pairs-array "K个逆序对数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/k-inverse-pairs-array) | Hard |
+| <span id="628">628</span> | [Maximum Product of Three Numbers](https://leetcode.com/problems/maximum-product-of-three-numbers "三个数的最大乘积") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-product-of-three-numbers) | Easy |
+| <span id="627">627</span> | [Swap Salary](https://leetcode.com/problems/swap-salary "交换工资") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/swap-salary) | Easy |
+| <span id="626">626</span> | [Exchange Seats](https://leetcode.com/problems/exchange-seats "换座位") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/exchange-seats) | Medium |
+| <span id="625">625</span> | [Minimum Factorization](https://leetcode.com/problems/minimum-factorization) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-factorization) | Medium |
+| <span id="624">624</span> | [Maximum Distance in Arrays](https://leetcode.com/problems/maximum-distance-in-arrays) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-distance-in-arrays) | Easy |
+| <span id="623">623</span> | [Add One Row to Tree](https://leetcode.com/problems/add-one-row-to-tree "在二叉树中增加一行") | [Go](https://github.com/openset/leetcode/tree/master/problems/add-one-row-to-tree) | Medium |
+| <span id="622">622</span> | [Design Circular Queue](https://leetcode.com/problems/design-circular-queue "设计循环队列") | [Go](https://github.com/openset/leetcode/tree/master/problems/design-circular-queue) | Medium |
+| <span id="621">621</span> | [Task Scheduler](https://leetcode.com/problems/task-scheduler "任务调度器") | [Go](https://github.com/openset/leetcode/tree/master/problems/task-scheduler) | Medium |
+| <span id="620">620</span> | [Not Boring Movies](https://leetcode.com/problems/not-boring-movies "有趣的电影") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/not-boring-movies) | Easy |
+| <span id="619">619</span> | [Biggest Single Number](https://leetcode.com/problems/biggest-single-number) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/biggest-single-number) | Easy |
+| <span id="618">618</span> | [Students Report By Geography](https://leetcode.com/problems/students-report-by-geography) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/students-report-by-geography) | Hard |
+| <span id="617">617</span> | [Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees "合并二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/merge-two-binary-trees) | Easy |
+| <span id="616">616</span> | [Add Bold Tag in String](https://leetcode.com/problems/add-bold-tag-in-string) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/add-bold-tag-in-string) | Medium |
+| <span id="615">615</span> | [Average Salary: Departments VS Company](https://leetcode.com/problems/average-salary-departments-vs-company) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/average-salary-departments-vs-company) | Hard |
+| <span id="614">614</span> | [Second Degree Follower](https://leetcode.com/problems/second-degree-follower) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/second-degree-follower) | Medium |
+| <span id="613">613</span> | [Shortest Distance in a Line](https://leetcode.com/problems/shortest-distance-in-a-line) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-distance-in-a-line) | Easy |
+| <span id="612">612</span> | [Shortest Distance in a Plane](https://leetcode.com/problems/shortest-distance-in-a-plane) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-distance-in-a-plane) | Medium |
+| <span id="611">611</span> | [Valid Triangle Number](https://leetcode.com/problems/valid-triangle-number "有效三角形的个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-triangle-number) | Medium |
+| <span id="610">610</span> | [Triangle Judgement](https://leetcode.com/problems/triangle-judgement) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/triangle-judgement) | Easy |
+| <span id="609">609</span> | [Find Duplicate File in System](https://leetcode.com/problems/find-duplicate-file-in-system "在系统中查找重复文件") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-duplicate-file-in-system) | Medium |
+| <span id="608">608</span> | [Tree Node](https://leetcode.com/problems/tree-node) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/tree-node) | Medium |
+| <span id="607">607</span> | [Sales Person](https://leetcode.com/problems/sales-person) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/sales-person) | Easy |
+| <span id="606">606</span> | [Construct String from Binary Tree](https://leetcode.com/problems/construct-string-from-binary-tree "根据二叉树创建字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/construct-string-from-binary-tree) | Easy |
+| <span id="605">605</span> | [Can Place Flowers](https://leetcode.com/problems/can-place-flowers "种花问题") | [Go](https://github.com/openset/leetcode/tree/master/problems/can-place-flowers) | Easy |
+| <span id="604">604</span> | [Design Compressed String Iterator](https://leetcode.com/problems/design-compressed-string-iterator) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/design-compressed-string-iterator) | Easy |
+| <span id="603">603</span> | [Consecutive Available Seats](https://leetcode.com/problems/consecutive-available-seats) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/consecutive-available-seats) | Easy |
+| <span id="602">602</span> | [Friend Requests II: Who Has the Most Friends](https://leetcode.com/problems/friend-requests-ii-who-has-the-most-friends) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/friend-requests-ii-who-has-the-most-friends) | Medium |
+| <span id="601">601</span> | [Human Traffic of Stadium](https://leetcode.com/problems/human-traffic-of-stadium "体育馆的人流量") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/human-traffic-of-stadium) | Hard |
+| <span id="600">600</span> | [Non-negative Integers without Consecutive Ones](https://leetcode.com/problems/non-negative-integers-without-consecutive-ones "不含连续1的非负整数") | [Go](https://github.com/openset/leetcode/tree/master/problems/non-negative-integers-without-consecutive-ones) | Hard |
+| <span id="599">599</span> | [Minimum Index Sum of Two Lists](https://leetcode.com/problems/minimum-index-sum-of-two-lists "两个列表的最小索引总和") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-index-sum-of-two-lists) | Easy |
+| <span id="598">598</span> | [Range Addition II](https://leetcode.com/problems/range-addition-ii "范围求和 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/range-addition-ii) | Easy |
+| <span id="597">597</span> | [Friend Requests I: Overall Acceptance Rate](https://leetcode.com/problems/friend-requests-i-overall-acceptance-rate) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/friend-requests-i-overall-acceptance-rate) | Easy |
+| <span id="596">596</span> | [Classes More Than 5 Students](https://leetcode.com/problems/classes-more-than-5-students "超过5名学生的课") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/classes-more-than-5-students) | Easy |
+| <span id="595">595</span> | [Big Countries](https://leetcode.com/problems/big-countries "大的国家") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/big-countries) | Easy |
+| <span id="594">594</span> | [Longest Harmonious Subsequence](https://leetcode.com/problems/longest-harmonious-subsequence "最长和谐子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-harmonious-subsequence) | Easy |
+| <span id="593">593</span> | [Valid Square](https://leetcode.com/problems/valid-square "有效的正方形") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-square) | Medium |
+| <span id="592">592</span> | [Fraction Addition and Subtraction](https://leetcode.com/problems/fraction-addition-and-subtraction "分数加减运算") | [Go](https://github.com/openset/leetcode/tree/master/problems/fraction-addition-and-subtraction) | Medium |
+| <span id="591">591</span> | [Tag Validator](https://leetcode.com/problems/tag-validator "标签验证器") | [Go](https://github.com/openset/leetcode/tree/master/problems/tag-validator) | Hard |
+| <span id="590">590</span> | [N-ary Tree Postorder Traversal](https://leetcode.com/problems/n-ary-tree-postorder-traversal "N叉树的后序遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/n-ary-tree-postorder-traversal) | Easy |
+| <span id="589">589</span> | [N-ary Tree Preorder Traversal](https://leetcode.com/problems/n-ary-tree-preorder-traversal "N叉树的前序遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/n-ary-tree-preorder-traversal) | Easy |
+| <span id="588">588</span> | [Design In-Memory File System](https://leetcode.com/problems/design-in-memory-file-system) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/design-in-memory-file-system) | Hard |
+| <span id="587">587</span> | [Erect the Fence](https://leetcode.com/problems/erect-the-fence "安装栅栏") | [Go](https://github.com/openset/leetcode/tree/master/problems/erect-the-fence) | Hard |
+| <span id="586">586</span> | [Customer Placing the Largest Number of Orders](https://leetcode.com/problems/customer-placing-the-largest-number-of-orders) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/customer-placing-the-largest-number-of-orders) | Easy |
+| <span id="585">585</span> | [Investments in 2016](https://leetcode.com/problems/investments-in-2016) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/investments-in-2016) | Medium |
+| <span id="584">584</span> | [Find Customer Referee](https://leetcode.com/problems/find-customer-referee) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/find-customer-referee) | Easy |
+| <span id="583">583</span> | [Delete Operation for Two Strings](https://leetcode.com/problems/delete-operation-for-two-strings "两个字符串的删除操作") | [Go](https://github.com/openset/leetcode/tree/master/problems/delete-operation-for-two-strings) | Medium |
+| <span id="582">582</span> | [Kill Process](https://leetcode.com/problems/kill-process) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/kill-process) | Medium |
+| <span id="581">581</span> | [Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/shortest-unsorted-continuous-subarray "最短无序连续子数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-unsorted-continuous-subarray) | Easy |
+| <span id="580">580</span> | [Count Student Number in Departments](https://leetcode.com/problems/count-student-number-in-departments) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/count-student-number-in-departments) | Medium |
+| <span id="579">579</span> | [Find Cumulative Salary of an Employee](https://leetcode.com/problems/find-cumulative-salary-of-an-employee) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/find-cumulative-salary-of-an-employee) | Hard |
+| <span id="578">578</span> | [Get Highest Answer Rate Question](https://leetcode.com/problems/get-highest-answer-rate-question) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/get-highest-answer-rate-question) | Medium |
+| <span id="577">577</span> | [Employee Bonus](https://leetcode.com/problems/employee-bonus) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/employee-bonus) | Easy |
+| <span id="576">576</span> | [Out of Boundary Paths](https://leetcode.com/problems/out-of-boundary-paths "出界的路径数") | [Go](https://github.com/openset/leetcode/tree/master/problems/out-of-boundary-paths) | Medium |
+| <span id="575">575</span> | [Distribute Candies](https://leetcode.com/problems/distribute-candies "分糖果") | [Go](https://github.com/openset/leetcode/tree/master/problems/distribute-candies) | Easy |
+| <span id="574">574</span> | [Winning Candidate](https://leetcode.com/problems/winning-candidate) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/winning-candidate) | Medium |
+| <span id="573">573</span> | [Squirrel Simulation](https://leetcode.com/problems/squirrel-simulation) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/squirrel-simulation) | Medium |
+| <span id="572">572</span> | [Subtree of Another Tree](https://leetcode.com/problems/subtree-of-another-tree "另一个树的子树") | [Go](https://github.com/openset/leetcode/tree/master/problems/subtree-of-another-tree) | Easy |
+| <span id="571">571</span> | [Find Median Given Frequency of Numbers](https://leetcode.com/problems/find-median-given-frequency-of-numbers) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/find-median-given-frequency-of-numbers) | Hard |
+| <span id="570">570</span> | [Managers with at Least 5 Direct Reports](https://leetcode.com/problems/managers-with-at-least-5-direct-reports) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/managers-with-at-least-5-direct-reports) | Medium |
+| <span id="569">569</span> | [Median Employee Salary](https://leetcode.com/problems/median-employee-salary) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/median-employee-salary) | Hard |
+| <span id="568">568</span> | [Maximum Vacation Days](https://leetcode.com/problems/maximum-vacation-days) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-vacation-days) | Hard |
+| <span id="567">567</span> | [Permutation in String](https://leetcode.com/problems/permutation-in-string "字符串的排列") | [Go](https://github.com/openset/leetcode/tree/master/problems/permutation-in-string) | Medium |
+| <span id="566">566</span> | [Reshape the Matrix](https://leetcode.com/problems/reshape-the-matrix "重塑矩阵") | [Go](https://github.com/openset/leetcode/tree/master/problems/reshape-the-matrix) | Easy |
+| <span id="565">565</span> | [Array Nesting](https://leetcode.com/problems/array-nesting "数组嵌套") | [Go](https://github.com/openset/leetcode/tree/master/problems/array-nesting) | Medium |
+| <span id="564">564</span> | [Find the Closest Palindrome](https://leetcode.com/problems/find-the-closest-palindrome "寻找最近的回文数") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-the-closest-palindrome) | Hard |
+| <span id="563">563</span> | [Binary Tree Tilt](https://leetcode.com/problems/binary-tree-tilt "二叉树的坡度") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-tilt) | Easy |
+| <span id="562">562</span> | [Longest Line of Consecutive One in Matrix](https://leetcode.com/problems/longest-line-of-consecutive-one-in-matrix) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-line-of-consecutive-one-in-matrix) | Medium |
+| <span id="561">561</span> | [Array Partition I](https://leetcode.com/problems/array-partition-i "数组拆分 I") | [Go](https://github.com/openset/leetcode/tree/master/problems/array-partition-i) | Easy |
+| <span id="560">560</span> | [Subarray Sum Equals K](https://leetcode.com/problems/subarray-sum-equals-k "和为K的子数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/subarray-sum-equals-k) | Medium |
+| <span id="559">559</span> | [Maximum Depth of N-ary Tree](https://leetcode.com/problems/maximum-depth-of-n-ary-tree "N叉树的最大深度") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-depth-of-n-ary-tree) | Easy |
+| <span id="558">558</span> | [Quad Tree Intersection](https://leetcode.com/problems/quad-tree-intersection "四叉树交集") | [Go](https://github.com/openset/leetcode/tree/master/problems/quad-tree-intersection) | Easy |
+| <span id="557">557</span> | [Reverse Words in a String III](https://leetcode.com/problems/reverse-words-in-a-string-iii "反转字符串中的单词 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-words-in-a-string-iii) | Easy |
+| <span id="556">556</span> | [Next Greater Element III](https://leetcode.com/problems/next-greater-element-iii "下一个更大元素 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/next-greater-element-iii) | Medium |
+| <span id="555">555</span> | [Split Concatenated Strings](https://leetcode.com/problems/split-concatenated-strings) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/split-concatenated-strings) | Medium |
+| <span id="554">554</span> | [Brick Wall](https://leetcode.com/problems/brick-wall "砖墙") | [Go](https://github.com/openset/leetcode/tree/master/problems/brick-wall) | Medium |
+| <span id="553">553</span> | [Optimal Division](https://leetcode.com/problems/optimal-division "最优除法") | [Go](https://github.com/openset/leetcode/tree/master/problems/optimal-division) | Medium |
+| <span id="552">552</span> | [Student Attendance Record II](https://leetcode.com/problems/student-attendance-record-ii "学生出勤记录 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/student-attendance-record-ii) | Hard |
+| <span id="551">551</span> | [Student Attendance Record I](https://leetcode.com/problems/student-attendance-record-i "学生出勤记录 I") | [Go](https://github.com/openset/leetcode/tree/master/problems/student-attendance-record-i) | Easy |
+| <span id="549">549</span> | [Binary Tree Longest Consecutive Sequence II](https://leetcode.com/problems/binary-tree-longest-consecutive-sequence-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-longest-consecutive-sequence-ii) | Medium |
+| <span id="548">548</span> | [Split Array with Equal Sum](https://leetcode.com/problems/split-array-with-equal-sum) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/split-array-with-equal-sum) | Medium |
+| <span id="547">547</span> | [Friend Circles](https://leetcode.com/problems/friend-circles "朋友圈") | [Go](https://github.com/openset/leetcode/tree/master/problems/friend-circles) | Medium |
+| <span id="546">546</span> | [Remove Boxes](https://leetcode.com/problems/remove-boxes "移除盒子") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-boxes) | Hard |
+| <span id="545">545</span> | [Boundary of Binary Tree](https://leetcode.com/problems/boundary-of-binary-tree) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/boundary-of-binary-tree) | Medium |
+| <span id="544">544</span> | [Output Contest Matches](https://leetcode.com/problems/output-contest-matches) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/output-contest-matches) | Medium |
+| <span id="543">543</span> | [Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree "二叉树的直径") | [Go](https://github.com/openset/leetcode/tree/master/problems/diameter-of-binary-tree) | Easy |
+| <span id="542">542</span> | [01 Matrix](https://leetcode.com/problems/01-matrix "01 矩阵") | [Go](https://github.com/openset/leetcode/tree/master/problems/01-matrix) | Medium |
+| <span id="541">541</span> | [Reverse String II](https://leetcode.com/problems/reverse-string-ii "反转字符串 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-string-ii) | Easy |
+| <span id="540">540</span> | [Single Element in a Sorted Array](https://leetcode.com/problems/single-element-in-a-sorted-array "有序数组中的单一元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/single-element-in-a-sorted-array) | Medium |
+| <span id="539">539</span> | [Minimum Time Difference](https://leetcode.com/problems/minimum-time-difference "最小时间差") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-time-difference) | Medium |
+| <span id="538">538</span> | [Convert BST to Greater Tree](https://leetcode.com/problems/convert-bst-to-greater-tree "把二叉搜索树转换为累加树") | [Go](https://github.com/openset/leetcode/tree/master/problems/convert-bst-to-greater-tree) | Easy |
+| <span id="537">537</span> | [Complex Number Multiplication](https://leetcode.com/problems/complex-number-multiplication "复数乘法") | [Go](https://github.com/openset/leetcode/tree/master/problems/complex-number-multiplication) | Medium |
+| <span id="536">536</span> | [Construct Binary Tree from String](https://leetcode.com/problems/construct-binary-tree-from-string) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/construct-binary-tree-from-string) | Medium |
+| <span id="535">535</span> | [Encode and Decode TinyURL](https://leetcode.com/problems/encode-and-decode-tinyurl "TinyURL 的加密与解密") | [Go](https://github.com/openset/leetcode/tree/master/problems/encode-and-decode-tinyurl) | Medium |
+| <span id="533">533</span> | [Lonely Pixel II](https://leetcode.com/problems/lonely-pixel-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/lonely-pixel-ii) | Medium |
+| <span id="532">532</span> | [K-diff Pairs in an Array](https://leetcode.com/problems/k-diff-pairs-in-an-array "数组中的K-diff数对") | [Go](https://github.com/openset/leetcode/tree/master/problems/k-diff-pairs-in-an-array) | Easy |
+| <span id="531">531</span> | [Lonely Pixel I](https://leetcode.com/problems/lonely-pixel-i) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/lonely-pixel-i) | Medium |
+| <span id="530">530</span> | [Minimum Absolute Difference in BST](https://leetcode.com/problems/minimum-absolute-difference-in-bst "二叉搜索树的最小绝对差") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-absolute-difference-in-bst) | Easy |
+| <span id="529">529</span> | [Minesweeper](https://leetcode.com/problems/minesweeper "扫雷游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/minesweeper) | Medium |
+| <span id="528">528</span> | [Random Pick with Weight](https://leetcode.com/problems/random-pick-with-weight "按权重随机选择") | [Go](https://github.com/openset/leetcode/tree/master/problems/random-pick-with-weight) | Medium |
+| <span id="527">527</span> | [Word Abbreviation](https://leetcode.com/problems/word-abbreviation) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/word-abbreviation) | Hard |
+| <span id="526">526</span> | [Beautiful Arrangement](https://leetcode.com/problems/beautiful-arrangement "优美的排列") | [Go](https://github.com/openset/leetcode/tree/master/problems/beautiful-arrangement) | Medium |
+| <span id="525">525</span> | [Contiguous Array](https://leetcode.com/problems/contiguous-array "连续数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/contiguous-array) | Medium |
+| <span id="524">524</span> | [Longest Word in Dictionary through Deleting](https://leetcode.com/problems/longest-word-in-dictionary-through-deleting "通过删除字母匹配到字典里最长单词") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-word-in-dictionary-through-deleting) | Medium |
+| <span id="523">523</span> | [Continuous Subarray Sum](https://leetcode.com/problems/continuous-subarray-sum "连续的子数组和") | [Go](https://github.com/openset/leetcode/tree/master/problems/continuous-subarray-sum) | Medium |
+| <span id="522">522</span> | [Longest Uncommon Subsequence II](https://leetcode.com/problems/longest-uncommon-subsequence-ii "最长特殊序列 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-uncommon-subsequence-ii) | Medium |
+| <span id="521">521</span> | [Longest Uncommon Subsequence I](https://leetcode.com/problems/longest-uncommon-subsequence-i "最长特殊序列 Ⅰ") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-uncommon-subsequence-i) | Easy |
+| <span id="520">520</span> | [Detect Capital](https://leetcode.com/problems/detect-capital "检测大写字母") | [Go](https://github.com/openset/leetcode/tree/master/problems/detect-capital) | Easy |
+| <span id="519">519</span> | [Random Flip Matrix](https://leetcode.com/problems/random-flip-matrix "随机翻转矩阵") | [Go](https://github.com/openset/leetcode/tree/master/problems/random-flip-matrix) | Medium |
+| <span id="518">518</span> | [Coin Change 2](https://leetcode.com/problems/coin-change-2 "零钱兑换 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/coin-change-2) | Medium |
+| <span id="517">517</span> | [Super Washing Machines](https://leetcode.com/problems/super-washing-machines "超级洗衣机") | [Go](https://github.com/openset/leetcode/tree/master/problems/super-washing-machines) | Hard |
+| <span id="516">516</span> | [Longest Palindromic Subsequence](https://leetcode.com/problems/longest-palindromic-subsequence "最长回文子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-palindromic-subsequence) | Medium |
+| <span id="515">515</span> | [Find Largest Value in Each Tree Row](https://leetcode.com/problems/find-largest-value-in-each-tree-row "在每个树行中找最大值") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-largest-value-in-each-tree-row) | Medium |
+| <span id="514">514</span> | [Freedom Trail](https://leetcode.com/problems/freedom-trail "自由之路") | [Go](https://github.com/openset/leetcode/tree/master/problems/freedom-trail) | Hard |
+| <span id="513">513</span> | [Find Bottom Left Tree Value](https://leetcode.com/problems/find-bottom-left-tree-value "找树左下角的值") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-bottom-left-tree-value) | Medium |
+| <span id="509">509</span> | [Fibonacci Number](https://leetcode.com/problems/fibonacci-number "斐波那契数") | [Go](https://github.com/openset/leetcode/tree/master/problems/fibonacci-number) | Easy |
+| <span id="508">508</span> | [Most Frequent Subtree Sum](https://leetcode.com/problems/most-frequent-subtree-sum "出现次数最多的子树元素和") | [Go](https://github.com/openset/leetcode/tree/master/problems/most-frequent-subtree-sum) | Medium |
+| <span id="507">507</span> | [Perfect Number](https://leetcode.com/problems/perfect-number "完美数") | [Go](https://github.com/openset/leetcode/tree/master/problems/perfect-number) | Easy |
+| <span id="506">506</span> | [Relative Ranks](https://leetcode.com/problems/relative-ranks "相对名次") | [Go](https://github.com/openset/leetcode/tree/master/problems/relative-ranks) | Easy |
+| <span id="505">505</span> | [The Maze II](https://leetcode.com/problems/the-maze-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/the-maze-ii) | Medium |
+| <span id="504">504</span> | [Base 7](https://leetcode.com/problems/base-7 "七进制数") | [Go](https://github.com/openset/leetcode/tree/master/problems/base-7) | Easy |
+| <span id="503">503</span> | [Next Greater Element II](https://leetcode.com/problems/next-greater-element-ii "下一个更大元素 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/next-greater-element-ii) | Medium |
+| <span id="502">502</span> | [IPO](https://leetcode.com/problems/ipo "IPO") | [Go](https://github.com/openset/leetcode/tree/master/problems/ipo) | Hard |
+| <span id="501">501</span> | [Find Mode in Binary Search Tree](https://leetcode.com/problems/find-mode-in-binary-search-tree "二叉搜索树中的众数") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-mode-in-binary-search-tree) | Easy |
+| <span id="500">500</span> | [Keyboard Row](https://leetcode.com/problems/keyboard-row "键盘行") | [Go](https://github.com/openset/leetcode/tree/master/problems/keyboard-row) | Easy |
+| <span id="499">499</span> | [The Maze III](https://leetcode.com/problems/the-maze-iii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/the-maze-iii) | Hard |
+| <span id="498">498</span> | [Diagonal Traverse](https://leetcode.com/problems/diagonal-traverse "对角线遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/diagonal-traverse) | Medium |
+| <span id="497">497</span> | [Random Point in Non-overlapping Rectangles](https://leetcode.com/problems/random-point-in-non-overlapping-rectangles "非重叠矩形中的随机点") | [Go](https://github.com/openset/leetcode/tree/master/problems/random-point-in-non-overlapping-rectangles) | Medium |
+| <span id="496">496</span> | [Next Greater Element I](https://leetcode.com/problems/next-greater-element-i "下一个更大元素 I") | [Go](https://github.com/openset/leetcode/tree/master/problems/next-greater-element-i) | Easy |
+| <span id="495">495</span> | [Teemo Attacking](https://leetcode.com/problems/teemo-attacking "提莫攻击") | [Go](https://github.com/openset/leetcode/tree/master/problems/teemo-attacking) | Medium |
+| <span id="494">494</span> | [Target Sum](https://leetcode.com/problems/target-sum "目标和") | [Go](https://github.com/openset/leetcode/tree/master/problems/target-sum) | Medium |
+| <span id="493">493</span> | [Reverse Pairs](https://leetcode.com/problems/reverse-pairs "翻转对") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-pairs) | Hard |
+| <span id="492">492</span> | [Construct the Rectangle](https://leetcode.com/problems/construct-the-rectangle "构造矩形") | [Go](https://github.com/openset/leetcode/tree/master/problems/construct-the-rectangle) | Easy |
+| <span id="491">491</span> | [Increasing Subsequences](https://leetcode.com/problems/increasing-subsequences "递增子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/increasing-subsequences) | Medium |
+| <span id="490">490</span> | [The Maze](https://leetcode.com/problems/the-maze) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/the-maze) | Medium |
+| <span id="489">489</span> | [Robot Room Cleaner](https://leetcode.com/problems/robot-room-cleaner) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/robot-room-cleaner) | Hard |
+| <span id="488">488</span> | [Zuma Game](https://leetcode.com/problems/zuma-game "祖玛游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/zuma-game) | Hard |
+| <span id="487">487</span> | [Max Consecutive Ones II](https://leetcode.com/problems/max-consecutive-ones-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/max-consecutive-ones-ii) | Medium |
+| <span id="486">486</span> | [Predict the Winner](https://leetcode.com/problems/predict-the-winner "预测赢家") | [Go](https://github.com/openset/leetcode/tree/master/problems/predict-the-winner) | Medium |
+| <span id="485">485</span> | [Max Consecutive Ones](https://leetcode.com/problems/max-consecutive-ones "最大连续1的个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/max-consecutive-ones) | Easy |
+| <span id="484">484</span> | [Find Permutation](https://leetcode.com/problems/find-permutation) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/find-permutation) | Medium |
+| <span id="483">483</span> | [Smallest Good Base](https://leetcode.com/problems/smallest-good-base "最小好进制") | [Go](https://github.com/openset/leetcode/tree/master/problems/smallest-good-base) | Hard |
+| <span id="482">482</span> | [License Key Formatting](https://leetcode.com/problems/license-key-formatting "密钥格式化") | [Go](https://github.com/openset/leetcode/tree/master/problems/license-key-formatting) | Easy |
+| <span id="481">481</span> | [Magical String](https://leetcode.com/problems/magical-string "神奇字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/magical-string) | Medium |
+| <span id="480">480</span> | [Sliding Window Median](https://leetcode.com/problems/sliding-window-median "滑动窗口中位数") | [Go](https://github.com/openset/leetcode/tree/master/problems/sliding-window-median) | Hard |
+| <span id="479">479</span> | [Largest Palindrome Product](https://leetcode.com/problems/largest-palindrome-product "最大回文数乘积") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-palindrome-product) | Hard |
+| <span id="478">478</span> | [Generate Random Point in a Circle](https://leetcode.com/problems/generate-random-point-in-a-circle "在圆内随机生成点") | [Go](https://github.com/openset/leetcode/tree/master/problems/generate-random-point-in-a-circle) | Medium |
+| <span id="477">477</span> | [Total Hamming Distance](https://leetcode.com/problems/total-hamming-distance "汉明距离总和") | [Go](https://github.com/openset/leetcode/tree/master/problems/total-hamming-distance) | Medium |
+| <span id="476">476</span> | [Number Complement](https://leetcode.com/problems/number-complement "数字的补数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-complement) | Easy |
+| <span id="475">475</span> | [Heaters](https://leetcode.com/problems/heaters "供暖器") | [Go](https://github.com/openset/leetcode/tree/master/problems/heaters) | Easy |
+| <span id="474">474</span> | [Ones and Zeroes](https://leetcode.com/problems/ones-and-zeroes "一和零") | [Go](https://github.com/openset/leetcode/tree/master/problems/ones-and-zeroes) | Medium |
+| <span id="473">473</span> | [Matchsticks to Square](https://leetcode.com/problems/matchsticks-to-square "火柴拼正方形") | [Go](https://github.com/openset/leetcode/tree/master/problems/matchsticks-to-square) | Medium |
+| <span id="472">472</span> | [Concatenated Words](https://leetcode.com/problems/concatenated-words "连接词") | [Go](https://github.com/openset/leetcode/tree/master/problems/concatenated-words) | Hard |
+| <span id="471">471</span> | [Encode String with Shortest Length](https://leetcode.com/problems/encode-string-with-shortest-length) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/encode-string-with-shortest-length) | Hard |
+| <span id="470">470</span> | [Implement Rand10() Using Rand7()](https://leetcode.com/problems/implement-rand10-using-rand7 "用 Rand7() 实现 Rand10()") | [Go](https://github.com/openset/leetcode/tree/master/problems/implement-rand10-using-rand7) | Medium |
+| <span id="469">469</span> | [Convex Polygon](https://leetcode.com/problems/convex-polygon) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/convex-polygon) | Medium |
+| <span id="468">468</span> | [Validate IP Address](https://leetcode.com/problems/validate-ip-address "验证IP地址") | [Go](https://github.com/openset/leetcode/tree/master/problems/validate-ip-address) | Medium |
+| <span id="467">467</span> | [Unique Substrings in Wraparound String](https://leetcode.com/problems/unique-substrings-in-wraparound-string "环绕字符串中唯一的子字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-substrings-in-wraparound-string) | Medium |
+| <span id="466">466</span> | [Count The Repetitions](https://leetcode.com/problems/count-the-repetitions "统计重复个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-the-repetitions) | Hard |
+| <span id="465">465</span> | [Optimal Account Balancing](https://leetcode.com/problems/optimal-account-balancing) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/optimal-account-balancing) | Hard |
+| <span id="464">464</span> | [Can I Win](https://leetcode.com/problems/can-i-win "我能赢吗") | [Go](https://github.com/openset/leetcode/tree/master/problems/can-i-win) | Medium |
+| <span id="463">463</span> | [Island Perimeter](https://leetcode.com/problems/island-perimeter "岛屿的周长") | [Go](https://github.com/openset/leetcode/tree/master/problems/island-perimeter) | Easy |
+| <span id="462">462</span> | [Minimum Moves to Equal Array Elements II](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii "最少移动次数使数组元素相等 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-moves-to-equal-array-elements-ii) | Medium |
+| <span id="461">461</span> | [Hamming Distance](https://leetcode.com/problems/hamming-distance "汉明距离") | [Go](https://github.com/openset/leetcode/tree/master/problems/hamming-distance) | Easy |
+| <span id="460">460</span> | [LFU Cache](https://leetcode.com/problems/lfu-cache "LFU缓存") | [Go](https://github.com/openset/leetcode/tree/master/problems/lfu-cache) | Hard |
+| <span id="459">459</span> | [Repeated Substring Pattern](https://leetcode.com/problems/repeated-substring-pattern "重复的子字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/repeated-substring-pattern) | Easy |
+| <span id="458">458</span> | [Poor Pigs](https://leetcode.com/problems/poor-pigs "可怜的小猪") | [Go](https://github.com/openset/leetcode/tree/master/problems/poor-pigs) | Easy |
+| <span id="457">457</span> | [Circular Array Loop](https://leetcode.com/problems/circular-array-loop "环形数组循环") | [Go](https://github.com/openset/leetcode/tree/master/problems/circular-array-loop) | Medium |
+| <span id="456">456</span> | [132 Pattern](https://leetcode.com/problems/132-pattern "132模式") | [Go](https://github.com/openset/leetcode/tree/master/problems/132-pattern) | Medium |
+| <span id="455">455</span> | [Assign Cookies](https://leetcode.com/problems/assign-cookies "分发饼干") | [Go](https://github.com/openset/leetcode/tree/master/problems/assign-cookies) | Easy |
+| <span id="454">454</span> | [4Sum II](https://leetcode.com/problems/4sum-ii "四数相加 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/4sum-ii) | Medium |
+| <span id="453">453</span> | [Minimum Moves to Equal Array Elements](https://leetcode.com/problems/minimum-moves-to-equal-array-elements "最小移动次数使数组元素相等") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-moves-to-equal-array-elements) | Easy |
+| <span id="452">452</span> | [Minimum Number of Arrows to Burst Balloons](https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons "用最少数量的箭引爆气球") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-number-of-arrows-to-burst-balloons) | Medium |
+| <span id="451">451</span> | [Sort Characters By Frequency](https://leetcode.com/problems/sort-characters-by-frequency "根据字符出现频率排序") | [Go](https://github.com/openset/leetcode/tree/master/problems/sort-characters-by-frequency) | Medium |
+| <span id="450">450</span> | [Delete Node in a BST](https://leetcode.com/problems/delete-node-in-a-bst "删除二叉搜索树中的节点") | [Go](https://github.com/openset/leetcode/tree/master/problems/delete-node-in-a-bst) | Medium |
+| <span id="449">449</span> | [Serialize and Deserialize BST](https://leetcode.com/problems/serialize-and-deserialize-bst "序列化和反序列化二叉搜索树") | [Go](https://github.com/openset/leetcode/tree/master/problems/serialize-and-deserialize-bst) | Medium |
+| <span id="448">448</span> | [Find All Numbers Disappeared in an Array](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array "找到所有数组中消失的数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-all-numbers-disappeared-in-an-array) | Easy |
+| <span id="447">447</span> | [Number of Boomerangs](https://leetcode.com/problems/number-of-boomerangs "回旋镖的数量") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-boomerangs) | Easy |
+| <span id="446">446</span> | [Arithmetic Slices II - Subsequence](https://leetcode.com/problems/arithmetic-slices-ii-subsequence "等差数列划分 II - 子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/arithmetic-slices-ii-subsequence) | Hard |
+| <span id="445">445</span> | [Add Two Numbers II](https://leetcode.com/problems/add-two-numbers-ii "两数相加 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/add-two-numbers-ii) | Medium |
+| <span id="444">444</span> | [Sequence Reconstruction](https://leetcode.com/problems/sequence-reconstruction) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/sequence-reconstruction) | Medium |
+| <span id="443">443</span> | [String Compression](https://leetcode.com/problems/string-compression "压缩字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/string-compression) | Easy |
+| <span id="442">442</span> | [Find All Duplicates in an Array](https://leetcode.com/problems/find-all-duplicates-in-an-array "数组中重复的数据") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-all-duplicates-in-an-array) | Medium |
+| <span id="441">441</span> | [Arranging Coins](https://leetcode.com/problems/arranging-coins "排列硬币") | [Go](https://github.com/openset/leetcode/tree/master/problems/arranging-coins) | Easy |
+| <span id="440">440</span> | [K-th Smallest in Lexicographical Order](https://leetcode.com/problems/k-th-smallest-in-lexicographical-order "字典序的第K小数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/k-th-smallest-in-lexicographical-order) | Hard |
+| <span id="439">439</span> | [Ternary Expression Parser](https://leetcode.com/problems/ternary-expression-parser) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/ternary-expression-parser) | Medium |
+| <span id="438">438</span> | [Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string "找到字符串中所有字母异位词") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-all-anagrams-in-a-string) | Easy |
+| <span id="437">437</span> | [Path Sum III](https://leetcode.com/problems/path-sum-iii "路径总和 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/path-sum-iii) | Easy |
+| <span id="436">436</span> | [Find Right Interval](https://leetcode.com/problems/find-right-interval "寻找右区间") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-right-interval) | Medium |
+| <span id="435">435</span> | [Non-overlapping Intervals](https://leetcode.com/problems/non-overlapping-intervals "无重叠区间") | [Go](https://github.com/openset/leetcode/tree/master/problems/non-overlapping-intervals) | Medium |
+| <span id="434">434</span> | [Number of Segments in a String](https://leetcode.com/problems/number-of-segments-in-a-string "字符串中的单词数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-segments-in-a-string) | Easy |
+| <span id="433">433</span> | [Minimum Genetic Mutation](https://leetcode.com/problems/minimum-genetic-mutation "最小基因变化") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-genetic-mutation) | Medium |
+| <span id="432">432</span> | [All O`one Data Structure](https://leetcode.com/problems/all-oone-data-structure "全 O(1) 的数据结构") | [Go](https://github.com/openset/leetcode/tree/master/problems/all-oone-data-structure) | Hard |
+| <span id="431">431</span> | [Encode N-ary Tree to Binary Tree](https://leetcode.com/problems/encode-n-ary-tree-to-binary-tree) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/encode-n-ary-tree-to-binary-tree) | Hard |
+| <span id="430">430</span> | [Flatten a Multilevel Doubly Linked List](https://leetcode.com/problems/flatten-a-multilevel-doubly-linked-list "扁平化多级双向链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/flatten-a-multilevel-doubly-linked-list) | Medium |
+| <span id="429">429</span> | [N-ary Tree Level Order Traversal](https://leetcode.com/problems/n-ary-tree-level-order-traversal "N叉树的层序遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/n-ary-tree-level-order-traversal) | Easy |
+| <span id="428">428</span> | [Serialize and Deserialize N-ary Tree](https://leetcode.com/problems/serialize-and-deserialize-n-ary-tree) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/serialize-and-deserialize-n-ary-tree) | Hard |
+| <span id="427">427</span> | [Construct Quad Tree](https://leetcode.com/problems/construct-quad-tree "建立四叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/construct-quad-tree) | Easy |
+| <span id="426">426</span> | [Convert Binary Search Tree to Sorted Doubly Linked List](https://leetcode.com/problems/convert-binary-search-tree-to-sorted-doubly-linked-list) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/convert-binary-search-tree-to-sorted-doubly-linked-list) | Medium |
+| <span id="425">425</span> | [Word Squares](https://leetcode.com/problems/word-squares) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/word-squares) | Hard |
+| <span id="424">424</span> | [Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement "替换后的最长重复字符") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-repeating-character-replacement) | Medium |
+| <span id="423">423</span> | [Reconstruct Original Digits from English](https://leetcode.com/problems/reconstruct-original-digits-from-english "从英文中重建数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/reconstruct-original-digits-from-english) | Medium |
+| <span id="422">422</span> | [Valid Word Square](https://leetcode.com/problems/valid-word-square) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-word-square) | Easy |
+| <span id="421">421</span> | [Maximum XOR of Two Numbers in an Array](https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array "数组中两个数的最大异或值") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-xor-of-two-numbers-in-an-array) | Medium |
+| <span id="420">420</span> | [Strong Password Checker](https://leetcode.com/problems/strong-password-checker "强密码检验器") | [Go](https://github.com/openset/leetcode/tree/master/problems/strong-password-checker) | Hard |
+| <span id="419">419</span> | [Battleships in a Board](https://leetcode.com/problems/battleships-in-a-board "甲板上的战舰") | [Go](https://github.com/openset/leetcode/tree/master/problems/battleships-in-a-board) | Medium |
+| <span id="418">418</span> | [Sentence Screen Fitting](https://leetcode.com/problems/sentence-screen-fitting) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/sentence-screen-fitting) | Medium |
+| <span id="417">417</span> | [Pacific Atlantic Water Flow](https://leetcode.com/problems/pacific-atlantic-water-flow "太平洋大西洋水流问题") | [Go](https://github.com/openset/leetcode/tree/master/problems/pacific-atlantic-water-flow) | Medium |
+| <span id="416">416</span> | [Partition Equal Subset Sum](https://leetcode.com/problems/partition-equal-subset-sum "分割等和子集") | [Go](https://github.com/openset/leetcode/tree/master/problems/partition-equal-subset-sum) | Medium |
+| <span id="415">415</span> | [Add Strings](https://leetcode.com/problems/add-strings "字符串相加") | [Go](https://github.com/openset/leetcode/tree/master/problems/add-strings) | Easy |
+| <span id="414">414</span> | [Third Maximum Number](https://leetcode.com/problems/third-maximum-number "第三大的数") | [Go](https://github.com/openset/leetcode/tree/master/problems/third-maximum-number) | Easy |
+| <span id="413">413</span> | [Arithmetic Slices](https://leetcode.com/problems/arithmetic-slices "等差数列划分") | [Go](https://github.com/openset/leetcode/tree/master/problems/arithmetic-slices) | Medium |
+| <span id="412">412</span> | [Fizz Buzz](https://leetcode.com/problems/fizz-buzz "Fizz Buzz") | [Go](https://github.com/openset/leetcode/tree/master/problems/fizz-buzz) | Easy |
+| <span id="411">411</span> | [Minimum Unique Word Abbreviation](https://leetcode.com/problems/minimum-unique-word-abbreviation) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-unique-word-abbreviation) | Hard |
+| <span id="410">410</span> | [Split Array Largest Sum](https://leetcode.com/problems/split-array-largest-sum "分割数组的最大值") | [Go](https://github.com/openset/leetcode/tree/master/problems/split-array-largest-sum) | Hard |
+| <span id="409">409</span> | [Longest Palindrome](https://leetcode.com/problems/longest-palindrome "最长回文串") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-palindrome) | Easy |
+| <span id="408">408</span> | [Valid Word Abbreviation](https://leetcode.com/problems/valid-word-abbreviation) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-word-abbreviation) | Easy |
+| <span id="407">407</span> | [Trapping Rain Water II](https://leetcode.com/problems/trapping-rain-water-ii "接雨水 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/trapping-rain-water-ii) | Hard |
+| <span id="406">406</span> | [Queue Reconstruction by Height](https://leetcode.com/problems/queue-reconstruction-by-height "根据身高重建队列") | [Go](https://github.com/openset/leetcode/tree/master/problems/queue-reconstruction-by-height) | Medium |
+| <span id="405">405</span> | [Convert a Number to Hexadecimal](https://leetcode.com/problems/convert-a-number-to-hexadecimal "数字转换为十六进制数") | [Go](https://github.com/openset/leetcode/tree/master/problems/convert-a-number-to-hexadecimal) | Easy |
+| <span id="404">404</span> | [Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves "左叶子之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/sum-of-left-leaves) | Easy |
+| <span id="403">403</span> | [Frog Jump](https://leetcode.com/problems/frog-jump "青蛙过河") | [Go](https://github.com/openset/leetcode/tree/master/problems/frog-jump) | Hard |
+| <span id="402">402</span> | [Remove K Digits](https://leetcode.com/problems/remove-k-digits "移掉K位数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-k-digits) | Medium |
+| <span id="401">401</span> | [Binary Watch](https://leetcode.com/problems/binary-watch "二进制手表") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-watch) | Easy |
+| <span id="400">400</span> | [Nth Digit](https://leetcode.com/problems/nth-digit "第N个数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/nth-digit) | Easy |
+| <span id="399">399</span> | [Evaluate Division](https://leetcode.com/problems/evaluate-division "除法求值") | [Go](https://github.com/openset/leetcode/tree/master/problems/evaluate-division) | Medium |
+| <span id="398">398</span> | [Random Pick Index](https://leetcode.com/problems/random-pick-index "随机数索引") | [Go](https://github.com/openset/leetcode/tree/master/problems/random-pick-index) | Medium |
+| <span id="397">397</span> | [Integer Replacement](https://leetcode.com/problems/integer-replacement "整数替换") | [Go](https://github.com/openset/leetcode/tree/master/problems/integer-replacement) | Medium |
+| <span id="396">396</span> | [Rotate Function](https://leetcode.com/problems/rotate-function "旋转函数") | [Go](https://github.com/openset/leetcode/tree/master/problems/rotate-function) | Medium |
+| <span id="395">395</span> | [Longest Substring with At Least K Repeating Characters](https://leetcode.com/problems/longest-substring-with-at-least-k-repeating-characters "至少有K个重复字符的最长子串") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-substring-with-at-least-k-repeating-characters) | Medium |
+| <span id="394">394</span> | [Decode String](https://leetcode.com/problems/decode-string "字符串解码") | [Go](https://github.com/openset/leetcode/tree/master/problems/decode-string) | Medium |
+| <span id="393">393</span> | [UTF-8 Validation](https://leetcode.com/problems/utf-8-validation "UTF-8 编码验证") | [Go](https://github.com/openset/leetcode/tree/master/problems/utf-8-validation) | Medium |
+| <span id="392">392</span> | [Is Subsequence](https://leetcode.com/problems/is-subsequence "判断子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/is-subsequence) | Medium |
+| <span id="391">391</span> | [Perfect Rectangle](https://leetcode.com/problems/perfect-rectangle "完美矩形") | [Go](https://github.com/openset/leetcode/tree/master/problems/perfect-rectangle) | Hard |
+| <span id="390">390</span> | [Elimination Game](https://leetcode.com/problems/elimination-game "消除游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/elimination-game) | Medium |
+| <span id="389">389</span> | [Find the Difference](https://leetcode.com/problems/find-the-difference "找不同") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-the-difference) | Easy |
+| <span id="388">388</span> | [Longest Absolute File Path](https://leetcode.com/problems/longest-absolute-file-path "文件的最长绝对路径") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-absolute-file-path) | Medium |
+| <span id="387">387</span> | [First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string "字符串中的第一个唯一字符") | [Go](https://github.com/openset/leetcode/tree/master/problems/first-unique-character-in-a-string) | Easy |
+| <span id="386">386</span> | [Lexicographical Numbers](https://leetcode.com/problems/lexicographical-numbers "字典序排数") | [Go](https://github.com/openset/leetcode/tree/master/problems/lexicographical-numbers) | Medium |
+| <span id="385">385</span> | [Mini Parser](https://leetcode.com/problems/mini-parser "迷你语法分析器") | [Go](https://github.com/openset/leetcode/tree/master/problems/mini-parser) | Medium |
+| <span id="384">384</span> | [Shuffle an Array](https://leetcode.com/problems/shuffle-an-array "打乱数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/shuffle-an-array) | Medium |
+| <span id="383">383</span> | [Ransom Note](https://leetcode.com/problems/ransom-note "赎金信") | [Go](https://github.com/openset/leetcode/tree/master/problems/ransom-note) | Easy |
+| <span id="382">382</span> | [Linked List Random Node](https://leetcode.com/problems/linked-list-random-node "链表随机节点") | [Go](https://github.com/openset/leetcode/tree/master/problems/linked-list-random-node) | Medium |
+| <span id="381">381</span> | [Insert Delete GetRandom O(1) - Duplicates allowed](https://leetcode.com/problems/insert-delete-getrandom-o1-duplicates-allowed "O(1) 时间插入、删除和获取随机元素 - 允许重复") | [Go](https://github.com/openset/leetcode/tree/master/problems/insert-delete-getrandom-o1-duplicates-allowed) | Hard |
+| <span id="380">380</span> | [Insert Delete GetRandom O(1)](https://leetcode.com/problems/insert-delete-getrandom-o1 "常数时间插入、删除和获取随机元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/insert-delete-getrandom-o1) | Medium |
+| <span id="379">379</span> | [Design Phone Directory](https://leetcode.com/problems/design-phone-directory) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/design-phone-directory) | Medium |
+| <span id="378">378</span> | [Kth Smallest Element in a Sorted Matrix](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix "有序矩阵中第K小的元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/kth-smallest-element-in-a-sorted-matrix) | Medium |
+| <span id="377">377</span> | [Combination Sum IV](https://leetcode.com/problems/combination-sum-iv "组合总和 Ⅳ") | [Go](https://github.com/openset/leetcode/tree/master/problems/combination-sum-iv) | Medium |
+| <span id="376">376</span> | [Wiggle Subsequence](https://leetcode.com/problems/wiggle-subsequence "摆动序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/wiggle-subsequence) | Medium |
+| <span id="375">375</span> | [Guess Number Higher or Lower II](https://leetcode.com/problems/guess-number-higher-or-lower-ii "猜数字大小 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/guess-number-higher-or-lower-ii) | Medium |
+| <span id="374">374</span> | [Guess Number Higher or Lower](https://leetcode.com/problems/guess-number-higher-or-lower "猜数字大小") | [Go](https://github.com/openset/leetcode/tree/master/problems/guess-number-higher-or-lower) | Easy |
+| <span id="373">373</span> | [Find K Pairs with Smallest Sums](https://leetcode.com/problems/find-k-pairs-with-smallest-sums "查找和最小的K对数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-k-pairs-with-smallest-sums) | Medium |
+| <span id="372">372</span> | [Super Pow](https://leetcode.com/problems/super-pow "超级次方") | [Go](https://github.com/openset/leetcode/tree/master/problems/super-pow) | Medium |
+| <span id="371">371</span> | [Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers "两整数之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/sum-of-two-integers) | Easy |
+| <span id="370">370</span> | [Range Addition](https://leetcode.com/problems/range-addition) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/range-addition) | Medium |
+| <span id="369">369</span> | [Plus One Linked List](https://leetcode.com/problems/plus-one-linked-list) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/plus-one-linked-list) | Medium |
+| <span id="368">368</span> | [Largest Divisible Subset](https://leetcode.com/problems/largest-divisible-subset "最大整除子集") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-divisible-subset) | Medium |
+| <span id="367">367</span> | [Valid Perfect Square](https://leetcode.com/problems/valid-perfect-square "有效的完全平方数") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-perfect-square) | Easy |
+| <span id="366">366</span> | [Find Leaves of Binary Tree](https://leetcode.com/problems/find-leaves-of-binary-tree) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/find-leaves-of-binary-tree) | Medium |
+| <span id="365">365</span> | [Water and Jug Problem](https://leetcode.com/problems/water-and-jug-problem "水壶问题") | [Go](https://github.com/openset/leetcode/tree/master/problems/water-and-jug-problem) | Medium |
+| <span id="364">364</span> | [Nested List Weight Sum II](https://leetcode.com/problems/nested-list-weight-sum-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/nested-list-weight-sum-ii) | Medium |
+| <span id="363">363</span> | [Max Sum of Rectangle No Larger Than K](https://leetcode.com/problems/max-sum-of-rectangle-no-larger-than-k "矩形区域不超过 K 的最大数值和") | [Go](https://github.com/openset/leetcode/tree/master/problems/max-sum-of-rectangle-no-larger-than-k) | Hard |
+| <span id="362">362</span> | [Design Hit Counter](https://leetcode.com/problems/design-hit-counter) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/design-hit-counter) | Medium |
+| <span id="361">361</span> | [Bomb Enemy](https://leetcode.com/problems/bomb-enemy) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/bomb-enemy) | Medium |
+| <span id="360">360</span> | [Sort Transformed Array](https://leetcode.com/problems/sort-transformed-array) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/sort-transformed-array) | Medium |
+| <span id="359">359</span> | [Logger Rate Limiter](https://leetcode.com/problems/logger-rate-limiter) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/logger-rate-limiter) | Easy |
+| <span id="358">358</span> | [Rearrange String k Distance Apart](https://leetcode.com/problems/rearrange-string-k-distance-apart) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/rearrange-string-k-distance-apart) | Hard |
+| <span id="357">357</span> | [Count Numbers with Unique Digits](https://leetcode.com/problems/count-numbers-with-unique-digits "计算各个位数不同的数字个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-numbers-with-unique-digits) | Medium |
+| <span id="356">356</span> | [Line Reflection](https://leetcode.com/problems/line-reflection) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/line-reflection) | Medium |
+| <span id="355">355</span> | [Design Twitter](https://leetcode.com/problems/design-twitter "设计推特") | [Go](https://github.com/openset/leetcode/tree/master/problems/design-twitter) | Medium |
+| <span id="354">354</span> | [Russian Doll Envelopes](https://leetcode.com/problems/russian-doll-envelopes "俄罗斯套娃信封问题") | [Go](https://github.com/openset/leetcode/tree/master/problems/russian-doll-envelopes) | Hard |
+| <span id="353">353</span> | [Design Snake Game](https://leetcode.com/problems/design-snake-game) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/design-snake-game) | Medium |
+| <span id="352">352</span> | [Data Stream as Disjoint Intervals](https://leetcode.com/problems/data-stream-as-disjoint-intervals "将数据流变为多个不相交间隔") | [Go](https://github.com/openset/leetcode/tree/master/problems/data-stream-as-disjoint-intervals) | Hard |
+| <span id="351">351</span> | [Android Unlock Patterns](https://leetcode.com/problems/android-unlock-patterns) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/android-unlock-patterns) | Medium |
+| <span id="350">350</span> | [Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii "两个数组的交集 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/intersection-of-two-arrays-ii) | Easy |
+| <span id="349">349</span> | [Intersection of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays "两个数组的交集") | [Go](https://github.com/openset/leetcode/tree/master/problems/intersection-of-two-arrays) | Easy |
+| <span id="348">348</span> | [Design Tic-Tac-Toe](https://leetcode.com/problems/design-tic-tac-toe) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/design-tic-tac-toe) | Medium |
+| <span id="347">347</span> | [Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements "前K个高频元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/top-k-frequent-elements) | Medium |
+| <span id="346">346</span> | [Moving Average from Data Stream](https://leetcode.com/problems/moving-average-from-data-stream) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/moving-average-from-data-stream) | Easy |
+| <span id="345">345</span> | [Reverse Vowels of a String](https://leetcode.com/problems/reverse-vowels-of-a-string "反转字符串中的元音字母") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-vowels-of-a-string) | Easy |
+| <span id="344">344</span> | [Reverse String](https://leetcode.com/problems/reverse-string "反转字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-string) | Easy |
+| <span id="343">343</span> | [Integer Break](https://leetcode.com/problems/integer-break "整数拆分") | [Go](https://github.com/openset/leetcode/tree/master/problems/integer-break) | Medium |
+| <span id="342">342</span> | [Power of Four](https://leetcode.com/problems/power-of-four "4的幂") | [Go](https://github.com/openset/leetcode/tree/master/problems/power-of-four) | Easy |
+| <span id="341">341</span> | [Flatten Nested List Iterator](https://leetcode.com/problems/flatten-nested-list-iterator "扁平化嵌套列表迭代器") | [Go](https://github.com/openset/leetcode/tree/master/problems/flatten-nested-list-iterator) | Medium |
+| <span id="340">340</span> | [Longest Substring with At Most K Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-substring-with-at-most-k-distinct-characters) | Hard |
+| <span id="339">339</span> | [Nested List Weight Sum](https://leetcode.com/problems/nested-list-weight-sum) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/nested-list-weight-sum) | Easy |
+| <span id="338">338</span> | [Counting Bits](https://leetcode.com/problems/counting-bits "比特位计数") | [Go](https://github.com/openset/leetcode/tree/master/problems/counting-bits) | Medium |
+| <span id="337">337</span> | [House Robber III](https://leetcode.com/problems/house-robber-iii "打家劫舍 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/house-robber-iii) | Medium |
+| <span id="336">336</span> | [Palindrome Pairs](https://leetcode.com/problems/palindrome-pairs "回文对") | [Go](https://github.com/openset/leetcode/tree/master/problems/palindrome-pairs) | Hard |
+| <span id="335">335</span> | [Self Crossing](https://leetcode.com/problems/self-crossing "路径交叉") | [Go](https://github.com/openset/leetcode/tree/master/problems/self-crossing) | Hard |
+| <span id="334">334</span> | [Increasing Triplet Subsequence](https://leetcode.com/problems/increasing-triplet-subsequence "递增的三元子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/increasing-triplet-subsequence) | Medium |
+| <span id="333">333</span> | [Largest BST Subtree](https://leetcode.com/problems/largest-bst-subtree) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-bst-subtree) | Medium |
+| <span id="332">332</span> | [Reconstruct Itinerary](https://leetcode.com/problems/reconstruct-itinerary "重新安排行程") | [Go](https://github.com/openset/leetcode/tree/master/problems/reconstruct-itinerary) | Medium |
+| <span id="331">331</span> | [Verify Preorder Serialization of a Binary Tree](https://leetcode.com/problems/verify-preorder-serialization-of-a-binary-tree "验证二叉树的前序序列化") | [Go](https://github.com/openset/leetcode/tree/master/problems/verify-preorder-serialization-of-a-binary-tree) | Medium |
+| <span id="330">330</span> | [Patching Array](https://leetcode.com/problems/patching-array "按要求补齐数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/patching-array) | Hard |
+| <span id="329">329</span> | [Longest Increasing Path in a Matrix](https://leetcode.com/problems/longest-increasing-path-in-a-matrix "矩阵中的最长递增路径") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-increasing-path-in-a-matrix) | Hard |
+| <span id="328">328</span> | [Odd Even Linked List](https://leetcode.com/problems/odd-even-linked-list "奇偶链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/odd-even-linked-list) | Medium |
+| <span id="327">327</span> | [Count of Range Sum](https://leetcode.com/problems/count-of-range-sum "区间和的个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-of-range-sum) | Hard |
+| <span id="326">326</span> | [Power of Three](https://leetcode.com/problems/power-of-three "3的幂") | [Go](https://github.com/openset/leetcode/tree/master/problems/power-of-three) | Easy |
+| <span id="325">325</span> | [Maximum Size Subarray Sum Equals k](https://leetcode.com/problems/maximum-size-subarray-sum-equals-k) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-size-subarray-sum-equals-k) | Medium |
+| <span id="324">324</span> | [Wiggle Sort II](https://leetcode.com/problems/wiggle-sort-ii "摆动排序 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/wiggle-sort-ii) | Medium |
+| <span id="323">323</span> | [Number of Connected Components in an Undirected Graph](https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-connected-components-in-an-undirected-graph) | Medium |
+| <span id="322">322</span> | [Coin Change](https://leetcode.com/problems/coin-change "零钱兑换") | [Go](https://github.com/openset/leetcode/tree/master/problems/coin-change) | Medium |
+| <span id="321">321</span> | [Create Maximum Number](https://leetcode.com/problems/create-maximum-number "拼接最大数") | [Go](https://github.com/openset/leetcode/tree/master/problems/create-maximum-number) | Hard |
+| <span id="320">320</span> | [Generalized Abbreviation](https://leetcode.com/problems/generalized-abbreviation) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/generalized-abbreviation) | Medium |
+| <span id="319">319</span> | [Bulb Switcher](https://leetcode.com/problems/bulb-switcher "灯泡开关") | [Go](https://github.com/openset/leetcode/tree/master/problems/bulb-switcher) | Medium |
+| <span id="318">318</span> | [Maximum Product of Word Lengths](https://leetcode.com/problems/maximum-product-of-word-lengths "最大单词长度乘积") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-product-of-word-lengths) | Medium |
+| <span id="317">317</span> | [Shortest Distance from All Buildings](https://leetcode.com/problems/shortest-distance-from-all-buildings) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-distance-from-all-buildings) | Hard |
+| <span id="316">316</span> | [Remove Duplicate Letters](https://leetcode.com/problems/remove-duplicate-letters "去除重复字母") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-duplicate-letters) | Hard |
+| <span id="315">315</span> | [Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self "计算右侧小于当前元素的个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-of-smaller-numbers-after-self) | Hard |
+| <span id="314">314</span> | [Binary Tree Vertical Order Traversal](https://leetcode.com/problems/binary-tree-vertical-order-traversal) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-vertical-order-traversal) | Medium |
+| <span id="313">313</span> | [Super Ugly Number](https://leetcode.com/problems/super-ugly-number "超级丑数") | [Go](https://github.com/openset/leetcode/tree/master/problems/super-ugly-number) | Medium |
+| <span id="312">312</span> | [Burst Balloons](https://leetcode.com/problems/burst-balloons "戳气球") | [Go](https://github.com/openset/leetcode/tree/master/problems/burst-balloons) | Hard |
+| <span id="311">311</span> | [Sparse Matrix Multiplication](https://leetcode.com/problems/sparse-matrix-multiplication) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/sparse-matrix-multiplication) | Medium |
+| <span id="310">310</span> | [Minimum Height Trees](https://leetcode.com/problems/minimum-height-trees "最小高度树") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-height-trees) | Medium |
+| <span id="309">309</span> | [Best Time to Buy and Sell Stock with Cooldown](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown "最佳买卖股票时机含冷冻期") | [Go](https://github.com/openset/leetcode/tree/master/problems/best-time-to-buy-and-sell-stock-with-cooldown) | Medium |
+| <span id="308">308</span> | [Range Sum Query 2D - Mutable](https://leetcode.com/problems/range-sum-query-2d-mutable) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/range-sum-query-2d-mutable) | Hard |
+| <span id="307">307</span> | [Range Sum Query - Mutable](https://leetcode.com/problems/range-sum-query-mutable "区域和检索 - 数组可修改") | [Go](https://github.com/openset/leetcode/tree/master/problems/range-sum-query-mutable) | Medium |
+| <span id="306">306</span> | [Additive Number](https://leetcode.com/problems/additive-number "累加数") | [Go](https://github.com/openset/leetcode/tree/master/problems/additive-number) | Medium |
+| <span id="305">305</span> | [Number of Islands II](https://leetcode.com/problems/number-of-islands-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-islands-ii) | Hard |
+| <span id="304">304</span> | [Range Sum Query 2D - Immutable](https://leetcode.com/problems/range-sum-query-2d-immutable "二维区域和检索 - 矩阵不可变") | [Go](https://github.com/openset/leetcode/tree/master/problems/range-sum-query-2d-immutable) | Medium |
+| <span id="303">303</span> | [Range Sum Query - Immutable](https://leetcode.com/problems/range-sum-query-immutable "区域和检索 - 数组不可变") | [Go](https://github.com/openset/leetcode/tree/master/problems/range-sum-query-immutable) | Easy |
+| <span id="302">302</span> | [Smallest Rectangle Enclosing Black Pixels](https://leetcode.com/problems/smallest-rectangle-enclosing-black-pixels) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/smallest-rectangle-enclosing-black-pixels) | Hard |
+| <span id="301">301</span> | [Remove Invalid Parentheses](https://leetcode.com/problems/remove-invalid-parentheses "删除无效的括号") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-invalid-parentheses) | Hard |
+| <span id="300">300</span> | [Longest Increasing Subsequence](https://leetcode.com/problems/longest-increasing-subsequence "最长上升子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-increasing-subsequence) | Medium |
+| <span id="299">299</span> | [Bulls and Cows](https://leetcode.com/problems/bulls-and-cows "猜数字游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/bulls-and-cows) | Medium |
+| <span id="298">298</span> | [Binary Tree Longest Consecutive Sequence](https://leetcode.com/problems/binary-tree-longest-consecutive-sequence) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-longest-consecutive-sequence) | Medium |
+| <span id="297">297</span> | [Serialize and Deserialize Binary Tree](https://leetcode.com/problems/serialize-and-deserialize-binary-tree "二叉树的序列化与反序列化") | [Go](https://github.com/openset/leetcode/tree/master/problems/serialize-and-deserialize-binary-tree) | Hard |
+| <span id="296">296</span> | [Best Meeting Point](https://leetcode.com/problems/best-meeting-point) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/best-meeting-point) | Hard |
+| <span id="295">295</span> | [Find Median from Data Stream](https://leetcode.com/problems/find-median-from-data-stream "数据流的中位数") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-median-from-data-stream) | Hard |
+| <span id="294">294</span> | [Flip Game II](https://leetcode.com/problems/flip-game-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/flip-game-ii) | Medium |
+| <span id="293">293</span> | [Flip Game](https://leetcode.com/problems/flip-game) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/flip-game) | Easy |
+| <span id="292">292</span> | [Nim Game](https://leetcode.com/problems/nim-game "Nim游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/nim-game) | Easy |
+| <span id="291">291</span> | [Word Pattern II](https://leetcode.com/problems/word-pattern-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/word-pattern-ii) | Hard |
+| <span id="290">290</span> | [Word Pattern](https://leetcode.com/problems/word-pattern "单词模式") | [Go](https://github.com/openset/leetcode/tree/master/problems/word-pattern) | Easy |
+| <span id="289">289</span> | [Game of Life](https://leetcode.com/problems/game-of-life "生命游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/game-of-life) | Medium |
+| <span id="288">288</span> | [Unique Word Abbreviation](https://leetcode.com/problems/unique-word-abbreviation) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-word-abbreviation) | Medium |
+| <span id="287">287</span> | [Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number "寻找重复数") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-the-duplicate-number) | Medium |
+| <span id="286">286</span> | [Walls and Gates](https://leetcode.com/problems/walls-and-gates) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/walls-and-gates) | Medium |
+| <span id="285">285</span> | [Inorder Successor in BST](https://leetcode.com/problems/inorder-successor-in-bst) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/inorder-successor-in-bst) | Medium |
+| <span id="284">284</span> | [Peeking Iterator](https://leetcode.com/problems/peeking-iterator "顶端迭代器") | [Go](https://github.com/openset/leetcode/tree/master/problems/peeking-iterator) | Medium |
+| <span id="283">283</span> | [Move Zeroes](https://leetcode.com/problems/move-zeroes "移动零") | [Go](https://github.com/openset/leetcode/tree/master/problems/move-zeroes) | Easy |
+| <span id="282">282</span> | [Expression Add Operators](https://leetcode.com/problems/expression-add-operators "给表达式添加运算符") | [Go](https://github.com/openset/leetcode/tree/master/problems/expression-add-operators) | Hard |
+| <span id="281">281</span> | [Zigzag Iterator](https://leetcode.com/problems/zigzag-iterator) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/zigzag-iterator) | Medium |
+| <span id="280">280</span> | [Wiggle Sort](https://leetcode.com/problems/wiggle-sort) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/wiggle-sort) | Medium |
+| <span id="279">279</span> | [Perfect Squares](https://leetcode.com/problems/perfect-squares "完全平方数") | [Go](https://github.com/openset/leetcode/tree/master/problems/perfect-squares) | Medium |
+| <span id="278">278</span> | [First Bad Version](https://leetcode.com/problems/first-bad-version "第一个错误的版本") | [Go](https://github.com/openset/leetcode/tree/master/problems/first-bad-version) | Easy |
+| <span id="277">277</span> | [Find the Celebrity](https://leetcode.com/problems/find-the-celebrity) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/find-the-celebrity) | Medium |
+| <span id="276">276</span> | [Paint Fence](https://leetcode.com/problems/paint-fence) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/paint-fence) | Easy |
+| <span id="275">275</span> | [H-Index II](https://leetcode.com/problems/h-index-ii "H指数 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/h-index-ii) | Medium |
+| <span id="274">274</span> | [H-Index](https://leetcode.com/problems/h-index "H指数") | [Go](https://github.com/openset/leetcode/tree/master/problems/h-index) | Medium |
+| <span id="273">273</span> | [Integer to English Words](https://leetcode.com/problems/integer-to-english-words "整数转换英文表示") | [Go](https://github.com/openset/leetcode/tree/master/problems/integer-to-english-words) | Hard |
+| <span id="272">272</span> | [Closest Binary Search Tree Value II](https://leetcode.com/problems/closest-binary-search-tree-value-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/closest-binary-search-tree-value-ii) | Hard |
+| <span id="271">271</span> | [Encode and Decode Strings](https://leetcode.com/problems/encode-and-decode-strings) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/encode-and-decode-strings) | Medium |
+| <span id="270">270</span> | [Closest Binary Search Tree Value](https://leetcode.com/problems/closest-binary-search-tree-value) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/closest-binary-search-tree-value) | Easy |
+| <span id="269">269</span> | [Alien Dictionary](https://leetcode.com/problems/alien-dictionary) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/alien-dictionary) | Hard |
+| <span id="268">268</span> | [Missing Number](https://leetcode.com/problems/missing-number "缺失数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/missing-number) | Easy |
+| <span id="267">267</span> | [Palindrome Permutation II](https://leetcode.com/problems/palindrome-permutation-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/palindrome-permutation-ii) | Medium |
+| <span id="266">266</span> | [Palindrome Permutation](https://leetcode.com/problems/palindrome-permutation) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/palindrome-permutation) | Easy |
+| <span id="265">265</span> | [Paint House II](https://leetcode.com/problems/paint-house-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/paint-house-ii) | Hard |
+| <span id="264">264</span> | [Ugly Number II](https://leetcode.com/problems/ugly-number-ii "丑数 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/ugly-number-ii) | Medium |
+| <span id="263">263</span> | [Ugly Number](https://leetcode.com/problems/ugly-number "丑数") | [Go](https://github.com/openset/leetcode/tree/master/problems/ugly-number) | Easy |
+| <span id="262">262</span> | [Trips and Users](https://leetcode.com/problems/trips-and-users "行程和用户") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/trips-and-users) | Hard |
+| <span id="261">261</span> | [Graph Valid Tree](https://leetcode.com/problems/graph-valid-tree) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/graph-valid-tree) | Medium |
+| <span id="260">260</span> | [Single Number III](https://leetcode.com/problems/single-number-iii "只出现一次的数字 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/single-number-iii) | Medium |
+| <span id="259">259</span> | [3Sum Smaller](https://leetcode.com/problems/3sum-smaller) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/3sum-smaller) | Medium |
+| <span id="258">258</span> | [Add Digits](https://leetcode.com/problems/add-digits "各位相加") | [Go](https://github.com/openset/leetcode/tree/master/problems/add-digits) | Easy |
+| <span id="257">257</span> | [Binary Tree Paths](https://leetcode.com/problems/binary-tree-paths "二叉树的所有路径") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-paths) | Easy |
+| <span id="256">256</span> | [Paint House](https://leetcode.com/problems/paint-house) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/paint-house) | Easy |
+| <span id="255">255</span> | [Verify Preorder Sequence in Binary Search Tree](https://leetcode.com/problems/verify-preorder-sequence-in-binary-search-tree) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/verify-preorder-sequence-in-binary-search-tree) | Medium |
+| <span id="254">254</span> | [Factor Combinations](https://leetcode.com/problems/factor-combinations) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/factor-combinations) | Medium |
+| <span id="253">253</span> | [Meeting Rooms II](https://leetcode.com/problems/meeting-rooms-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/meeting-rooms-ii) | Medium |
+| <span id="252">252</span> | [Meeting Rooms](https://leetcode.com/problems/meeting-rooms) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/meeting-rooms) | Easy |
+| <span id="251">251</span> | [Flatten 2D Vector](https://leetcode.com/problems/flatten-2d-vector) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/flatten-2d-vector) | Medium |
+| <span id="250">250</span> | [Count Univalue Subtrees](https://leetcode.com/problems/count-univalue-subtrees) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/count-univalue-subtrees) | Medium |
+| <span id="249">249</span> | [Group Shifted Strings](https://leetcode.com/problems/group-shifted-strings) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/group-shifted-strings) | Medium |
+| <span id="248">248</span> | [Strobogrammatic Number III](https://leetcode.com/problems/strobogrammatic-number-iii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/strobogrammatic-number-iii) | Hard |
+| <span id="247">247</span> | [Strobogrammatic Number II](https://leetcode.com/problems/strobogrammatic-number-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/strobogrammatic-number-ii) | Medium |
+| <span id="246">246</span> | [Strobogrammatic Number](https://leetcode.com/problems/strobogrammatic-number) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/strobogrammatic-number) | Easy |
+| <span id="245">245</span> | [Shortest Word Distance III](https://leetcode.com/problems/shortest-word-distance-iii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-word-distance-iii) | Medium |
+| <span id="244">244</span> | [Shortest Word Distance II](https://leetcode.com/problems/shortest-word-distance-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-word-distance-ii) | Medium |
+| <span id="243">243</span> | [Shortest Word Distance](https://leetcode.com/problems/shortest-word-distance) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-word-distance) | Easy |
+| <span id="242">242</span> | [Valid Anagram](https://leetcode.com/problems/valid-anagram "有效的字母异位词") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-anagram) | Easy |
+| <span id="241">241</span> | [Different Ways to Add Parentheses](https://leetcode.com/problems/different-ways-to-add-parentheses "为运算表达式设计优先级") | [Go](https://github.com/openset/leetcode/tree/master/problems/different-ways-to-add-parentheses) | Medium |
+| <span id="240">240</span> | [Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii "搜索二维矩阵 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/search-a-2d-matrix-ii) | Medium |
+| <span id="239">239</span> | [Sliding Window Maximum](https://leetcode.com/problems/sliding-window-maximum "滑动窗口最大值") | [Go](https://github.com/openset/leetcode/tree/master/problems/sliding-window-maximum) | Hard |
+| <span id="238">238</span> | [Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self "除自身以外数组的乘积") | [Go](https://github.com/openset/leetcode/tree/master/problems/product-of-array-except-self) | Medium |
+| <span id="237">237</span> | [Delete Node in a Linked List](https://leetcode.com/problems/delete-node-in-a-linked-list "删除链表中的节点") | [Go](https://github.com/openset/leetcode/tree/master/problems/delete-node-in-a-linked-list) | Easy |
+| <span id="236">236</span> | [Lowest Common Ancestor of a Binary Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree "二叉树的最近公共祖先") | [Go](https://github.com/openset/leetcode/tree/master/problems/lowest-common-ancestor-of-a-binary-tree) | Medium |
+| <span id="235">235</span> | [Lowest Common Ancestor of a Binary Search Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree "二叉搜索树的最近公共祖先") | [Go](https://github.com/openset/leetcode/tree/master/problems/lowest-common-ancestor-of-a-binary-search-tree) | Easy |
+| <span id="234">234</span> | [Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list "回文链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/palindrome-linked-list) | Easy |
+| <span id="233">233</span> | [Number of Digit One](https://leetcode.com/problems/number-of-digit-one "数字1的个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-digit-one) | Hard |
+| <span id="232">232</span> | [Implement Queue using Stacks](https://leetcode.com/problems/implement-queue-using-stacks "用栈实现队列") | [Go](https://github.com/openset/leetcode/tree/master/problems/implement-queue-using-stacks) | Easy |
+| <span id="231">231</span> | [Power of Two](https://leetcode.com/problems/power-of-two "2的幂") | [Go](https://github.com/openset/leetcode/tree/master/problems/power-of-two) | Easy |
+| <span id="230">230</span> | [Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst "二叉搜索树中第K小的元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/kth-smallest-element-in-a-bst) | Medium |
+| <span id="229">229</span> | [Majority Element II](https://leetcode.com/problems/majority-element-ii "求众数 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/majority-element-ii) | Medium |
+| <span id="228">228</span> | [Summary Ranges](https://leetcode.com/problems/summary-ranges "汇总区间") | [Go](https://github.com/openset/leetcode/tree/master/problems/summary-ranges) | Medium |
+| <span id="227">227</span> | [Basic Calculator II](https://leetcode.com/problems/basic-calculator-ii "基本计算器 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/basic-calculator-ii) | Medium |
+| <span id="226">226</span> | [Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree "翻转二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/invert-binary-tree) | Easy |
+| <span id="225">225</span> | [Implement Stack using Queues](https://leetcode.com/problems/implement-stack-using-queues "用队列实现栈") | [Go](https://github.com/openset/leetcode/tree/master/problems/implement-stack-using-queues) | Easy |
+| <span id="224">224</span> | [Basic Calculator](https://leetcode.com/problems/basic-calculator "基本计算器") | [Go](https://github.com/openset/leetcode/tree/master/problems/basic-calculator) | Hard |
+| <span id="223">223</span> | [Rectangle Area](https://leetcode.com/problems/rectangle-area "矩形面积") | [Go](https://github.com/openset/leetcode/tree/master/problems/rectangle-area) | Medium |
+| <span id="222">222</span> | [Count Complete Tree Nodes](https://leetcode.com/problems/count-complete-tree-nodes "完全二叉树的节点个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-complete-tree-nodes) | Medium |
+| <span id="221">221</span> | [Maximal Square](https://leetcode.com/problems/maximal-square "最大正方形") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximal-square) | Medium |
+| <span id="220">220</span> | [Contains Duplicate III](https://leetcode.com/problems/contains-duplicate-iii "存在重复元素 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/contains-duplicate-iii) | Medium |
+| <span id="219">219</span> | [Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii "存在重复元素 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/contains-duplicate-ii) | Easy |
+| <span id="218">218</span> | [The Skyline Problem](https://leetcode.com/problems/the-skyline-problem "天际线问题") | [Go](https://github.com/openset/leetcode/tree/master/problems/the-skyline-problem) | Hard |
+| <span id="217">217</span> | [Contains Duplicate](https://leetcode.com/problems/contains-duplicate "存在重复元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/contains-duplicate) | Easy |
+| <span id="216">216</span> | [Combination Sum III](https://leetcode.com/problems/combination-sum-iii "组合总和 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/combination-sum-iii) | Medium |
+| <span id="215">215</span> | [Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array "数组中的第K个最大元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/kth-largest-element-in-an-array) | Medium |
+| <span id="214">214</span> | [Shortest Palindrome](https://leetcode.com/problems/shortest-palindrome "最短回文串") | [Go](https://github.com/openset/leetcode/tree/master/problems/shortest-palindrome) | Hard |
+| <span id="213">213</span> | [House Robber II](https://leetcode.com/problems/house-robber-ii "打家劫舍 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/house-robber-ii) | Medium |
+| <span id="212">212</span> | [Word Search II](https://leetcode.com/problems/word-search-ii "单词搜索 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/word-search-ii) | Hard |
+| <span id="211">211</span> | [Add and Search Word - Data structure design](https://leetcode.com/problems/add-and-search-word-data-structure-design "添加与搜索单词 - 数据结构设计") | [Go](https://github.com/openset/leetcode/tree/master/problems/add-and-search-word-data-structure-design) | Medium |
+| <span id="210">210</span> | [Course Schedule II](https://leetcode.com/problems/course-schedule-ii "课程表 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/course-schedule-ii) | Medium |
+| <span id="209">209</span> | [Minimum Size Subarray Sum](https://leetcode.com/problems/minimum-size-subarray-sum "长度最小的子数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-size-subarray-sum) | Medium |
+| <span id="208">208</span> | [Implement Trie (Prefix Tree)](https://leetcode.com/problems/implement-trie-prefix-tree "实现 Trie (前缀树)") | [Go](https://github.com/openset/leetcode/tree/master/problems/implement-trie-prefix-tree) | Medium |
+| <span id="207">207</span> | [Course Schedule](https://leetcode.com/problems/course-schedule "课程表") | [Go](https://github.com/openset/leetcode/tree/master/problems/course-schedule) | Medium |
+| <span id="206">206</span> | [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list "反转链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-linked-list) | Easy |
+| <span id="205">205</span> | [Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings "同构字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/isomorphic-strings) | Easy |
+| <span id="204">204</span> | [Count Primes](https://leetcode.com/problems/count-primes "计数质数") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-primes) | Easy |
+| <span id="203">203</span> | [Remove Linked List Elements](https://leetcode.com/problems/remove-linked-list-elements "移除链表元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-linked-list-elements) | Easy |
+| <span id="202">202</span> | [Happy Number](https://leetcode.com/problems/happy-number "快乐数") | [Go](https://github.com/openset/leetcode/tree/master/problems/happy-number) | Easy |
+| <span id="201">201</span> | [Bitwise AND of Numbers Range](https://leetcode.com/problems/bitwise-and-of-numbers-range "数字范围按位与") | [Go](https://github.com/openset/leetcode/tree/master/problems/bitwise-and-of-numbers-range) | Medium |
+| <span id="200">200</span> | [Number of Islands](https://leetcode.com/problems/number-of-islands "岛屿的个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-islands) | Medium |
+| <span id="199">199</span> | [Binary Tree Right Side View](https://leetcode.com/problems/binary-tree-right-side-view "二叉树的右视图") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-right-side-view) | Medium |
+| <span id="198">198</span> | [House Robber](https://leetcode.com/problems/house-robber "打家劫舍") | [Go](https://github.com/openset/leetcode/tree/master/problems/house-robber) | Easy |
+| <span id="197">197</span> | [Rising Temperature](https://leetcode.com/problems/rising-temperature "上升的温度") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/rising-temperature) | Easy |
+| <span id="196">196</span> | [Delete Duplicate Emails](https://leetcode.com/problems/delete-duplicate-emails "删除重复的电子邮箱") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/delete-duplicate-emails) | Easy |
+| <span id="195">195</span> | [Tenth Line](https://leetcode.com/problems/tenth-line "第十行") | [Bash](https://github.com/openset/leetcode/tree/master/problems/tenth-line) | Easy |
+| <span id="194">194</span> | [Transpose File](https://leetcode.com/problems/transpose-file "转置文件") | [Bash](https://github.com/openset/leetcode/tree/master/problems/transpose-file) | Medium |
+| <span id="193">193</span> | [Valid Phone Numbers](https://leetcode.com/problems/valid-phone-numbers "有效电话号码") | [Bash](https://github.com/openset/leetcode/tree/master/problems/valid-phone-numbers) | Easy |
+| <span id="192">192</span> | [Word Frequency](https://leetcode.com/problems/word-frequency "统计词频") | [Bash](https://github.com/openset/leetcode/tree/master/problems/word-frequency) | Medium |
+| <span id="191">191</span> | [Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits "位1的个数") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-1-bits) | Easy |
+| <span id="190">190</span> | [Reverse Bits](https://leetcode.com/problems/reverse-bits "颠倒二进制位") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-bits) | Easy |
+| <span id="189">189</span> | [Rotate Array](https://leetcode.com/problems/rotate-array "旋转数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/rotate-array) | Easy |
+| <span id="188">188</span> | [Best Time to Buy and Sell Stock IV](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv "买卖股票的最佳时机 IV") | [Go](https://github.com/openset/leetcode/tree/master/problems/best-time-to-buy-and-sell-stock-iv) | Hard |
+| <span id="187">187</span> | [Repeated DNA Sequences](https://leetcode.com/problems/repeated-dna-sequences "重复的DNA序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/repeated-dna-sequences) | Medium |
+| <span id="186">186</span> | [Reverse Words in a String II](https://leetcode.com/problems/reverse-words-in-a-string-ii) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-words-in-a-string-ii) | Medium |
+| <span id="185">185</span> | [Department Top Three Salaries](https://leetcode.com/problems/department-top-three-salaries "部门工资前三高的员工") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/department-top-three-salaries) | Hard |
+| <span id="184">184</span> | [Department Highest Salary](https://leetcode.com/problems/department-highest-salary "部门工资最高的员工") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/department-highest-salary) | Medium |
+| <span id="183">183</span> | [Customers Who Never Order](https://leetcode.com/problems/customers-who-never-order "从不订购的客户") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/customers-who-never-order) | Easy |
+| <span id="182">182</span> | [Duplicate Emails](https://leetcode.com/problems/duplicate-emails "查找重复的电子邮箱") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/duplicate-emails) | Easy |
+| <span id="181">181</span> | [Employees Earning More Than Their Managers](https://leetcode.com/problems/employees-earning-more-than-their-managers "超过经理收入的员工") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/employees-earning-more-than-their-managers) | Easy |
+| <span id="180">180</span> | [Consecutive Numbers](https://leetcode.com/problems/consecutive-numbers "连续出现的数字") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/consecutive-numbers) | Medium |
+| <span id="179">179</span> | [Largest Number](https://leetcode.com/problems/largest-number "最大数") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-number) | Medium |
+| <span id="178">178</span> | [Rank Scores](https://leetcode.com/problems/rank-scores "分数排名") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/rank-scores) | Medium |
+| <span id="177">177</span> | [Nth Highest Salary](https://leetcode.com/problems/nth-highest-salary "第N高的薪水") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/nth-highest-salary) | Medium |
+| <span id="176">176</span> | [Second Highest Salary](https://leetcode.com/problems/second-highest-salary "第二高的薪水") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/second-highest-salary) | Easy |
+| <span id="175">175</span> | [Combine Two Tables](https://leetcode.com/problems/combine-two-tables "组合两个表") | [MySQL](https://github.com/openset/leetcode/tree/master/problems/combine-two-tables) | Easy |
+| <span id="174">174</span> | [Dungeon Game](https://leetcode.com/problems/dungeon-game "地下城游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/dungeon-game) | Hard |
+| <span id="173">173</span> | [Binary Search Tree Iterator](https://leetcode.com/problems/binary-search-tree-iterator "二叉搜索树迭代器") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-search-tree-iterator) | Medium |
+| <span id="172">172</span> | [Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes "阶乘后的零") | [Go](https://github.com/openset/leetcode/tree/master/problems/factorial-trailing-zeroes) | Easy |
+| <span id="171">171</span> | [Excel Sheet Column Number](https://leetcode.com/problems/excel-sheet-column-number "Excel表列序号") | [Go](https://github.com/openset/leetcode/tree/master/problems/excel-sheet-column-number) | Easy |
+| <span id="170">170</span> | [Two Sum III - Data structure design](https://leetcode.com/problems/two-sum-iii-data-structure-design) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/two-sum-iii-data-structure-design) | Easy |
+| <span id="169">169</span> | [Majority Element](https://leetcode.com/problems/majority-element "求众数") | [Go](https://github.com/openset/leetcode/tree/master/problems/majority-element) | Easy |
+| <span id="168">168</span> | [Excel Sheet Column Title](https://leetcode.com/problems/excel-sheet-column-title "Excel表列名称") | [Go](https://github.com/openset/leetcode/tree/master/problems/excel-sheet-column-title) | Easy |
+| <span id="167">167</span> | [Two Sum II - Input array is sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted "两数之和 II - 输入有序数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/two-sum-ii-input-array-is-sorted) | Easy |
+| <span id="166">166</span> | [Fraction to Recurring Decimal](https://leetcode.com/problems/fraction-to-recurring-decimal "分数到小数") | [Go](https://github.com/openset/leetcode/tree/master/problems/fraction-to-recurring-decimal) | Medium |
+| <span id="165">165</span> | [Compare Version Numbers](https://leetcode.com/problems/compare-version-numbers "比较版本号") | [Go](https://github.com/openset/leetcode/tree/master/problems/compare-version-numbers) | Medium |
+| <span id="164">164</span> | [Maximum Gap](https://leetcode.com/problems/maximum-gap "最大间距") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-gap) | Hard |
+| <span id="163">163</span> | [Missing Ranges](https://leetcode.com/problems/missing-ranges) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/missing-ranges) | Medium |
+| <span id="162">162</span> | [Find Peak Element](https://leetcode.com/problems/find-peak-element "寻找峰值") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-peak-element) | Medium |
+| <span id="161">161</span> | [One Edit Distance](https://leetcode.com/problems/one-edit-distance) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/one-edit-distance) | Medium |
+| <span id="160">160</span> | [Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists "相交链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/intersection-of-two-linked-lists) | Easy |
+| <span id="159">159</span> | [Longest Substring with At Most Two Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-substring-with-at-most-two-distinct-characters) | Hard |
+| <span id="158">158</span> | [Read N Characters Given Read4 II - Call multiple times](https://leetcode.com/problems/read-n-characters-given-read4-ii-call-multiple-times) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/read-n-characters-given-read4-ii-call-multiple-times) | Hard |
+| <span id="157">157</span> | [Read N Characters Given Read4](https://leetcode.com/problems/read-n-characters-given-read4) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/read-n-characters-given-read4) | Easy |
+| <span id="156">156</span> | [Binary Tree Upside Down](https://leetcode.com/problems/binary-tree-upside-down) &hearts; | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-upside-down) | Medium |
+| <span id="155">155</span> | [Min Stack](https://leetcode.com/problems/min-stack "最小栈") | [Go](https://github.com/openset/leetcode/tree/master/problems/min-stack) | Easy |
+| <span id="154">154</span> | [Find Minimum in Rotated Sorted Array II](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii "寻找旋转排序数组中的最小值 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-minimum-in-rotated-sorted-array-ii) | Hard |
+| <span id="153">153</span> | [Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array "寻找旋转排序数组中的最小值") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-minimum-in-rotated-sorted-array) | Medium |
+| <span id="152">152</span> | [Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray "乘积最大子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-product-subarray) | Medium |
+| <span id="151">151</span> | [Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string "翻转字符串里的单词") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-words-in-a-string) | Medium |
+| <span id="150">150</span> | [Evaluate Reverse Polish Notation](https://leetcode.com/problems/evaluate-reverse-polish-notation "逆波兰表达式求值") | [Go](https://github.com/openset/leetcode/tree/master/problems/evaluate-reverse-polish-notation) | Medium |
+| <span id="149">149</span> | [Max Points on a Line](https://leetcode.com/problems/max-points-on-a-line "直线上最多的点数") | [Go](https://github.com/openset/leetcode/tree/master/problems/max-points-on-a-line) | Hard |
+| <span id="148">148</span> | [Sort List](https://leetcode.com/problems/sort-list "排序链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/sort-list) | Medium |
+| <span id="147">147</span> | [Insertion Sort List](https://leetcode.com/problems/insertion-sort-list "对链表进行插入排序") | [Go](https://github.com/openset/leetcode/tree/master/problems/insertion-sort-list) | Medium |
+| <span id="146">146</span> | [LRU Cache](https://leetcode.com/problems/lru-cache "LRU缓存机制") | [Go](https://github.com/openset/leetcode/tree/master/problems/lru-cache) | Hard |
+| <span id="145">145</span> | [Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal "二叉树的后序遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-postorder-traversal) | Hard |
+| <span id="144">144</span> | [Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal "二叉树的前序遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-preorder-traversal) | Medium |
+| <span id="143">143</span> | [Reorder List](https://leetcode.com/problems/reorder-list "重排链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/reorder-list) | Medium |
+| <span id="142">142</span> | [Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii "环形链表 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/linked-list-cycle-ii) | Medium |
+| <span id="141">141</span> | [Linked List Cycle](https://leetcode.com/problems/linked-list-cycle "环形链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/linked-list-cycle) | Easy |
+| <span id="140">140</span> | [Word Break II](https://leetcode.com/problems/word-break-ii "单词拆分 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/word-break-ii) | Hard |
+| <span id="139">139</span> | [Word Break](https://leetcode.com/problems/word-break "单词拆分") | [Go](https://github.com/openset/leetcode/tree/master/problems/word-break) | Medium |
+| <span id="138">138</span> | [Copy List with Random Pointer](https://leetcode.com/problems/copy-list-with-random-pointer "复制带随机指针的链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/copy-list-with-random-pointer) | Medium |
+| <span id="137">137</span> | [Single Number II](https://leetcode.com/problems/single-number-ii "只出现一次的数字 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/single-number-ii) | Medium |
+| <span id="136">136</span> | [Single Number](https://leetcode.com/problems/single-number "只出现一次的数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/single-number) | Easy |
+| <span id="135">135</span> | [Candy](https://leetcode.com/problems/candy "分发糖果") | [Go](https://github.com/openset/leetcode/tree/master/problems/candy) | Hard |
+| <span id="134">134</span> | [Gas Station](https://leetcode.com/problems/gas-station "加油站") | [Go](https://github.com/openset/leetcode/tree/master/problems/gas-station) | Medium |
+| <span id="133">133</span> | [Clone Graph](https://leetcode.com/problems/clone-graph "克隆图") | [Go](https://github.com/openset/leetcode/tree/master/problems/clone-graph) | Medium |
+| <span id="132">132</span> | [Palindrome Partitioning II](https://leetcode.com/problems/palindrome-partitioning-ii "分割回文串 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/palindrome-partitioning-ii) | Hard |
+| <span id="131">131</span> | [Palindrome Partitioning](https://leetcode.com/problems/palindrome-partitioning "分割回文串") | [Go](https://github.com/openset/leetcode/tree/master/problems/palindrome-partitioning) | Medium |
+| <span id="130">130</span> | [Surrounded Regions](https://leetcode.com/problems/surrounded-regions "被围绕的区域") | [Go](https://github.com/openset/leetcode/tree/master/problems/surrounded-regions) | Medium |
+| <span id="129">129</span> | [Sum Root to Leaf Numbers](https://leetcode.com/problems/sum-root-to-leaf-numbers "求根到叶子节点数字之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/sum-root-to-leaf-numbers) | Medium |
+| <span id="128">128</span> | [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence "最长连续序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-consecutive-sequence) | Hard |
+| <span id="127">127</span> | [Word Ladder](https://leetcode.com/problems/word-ladder "单词接龙") | [Go](https://github.com/openset/leetcode/tree/master/problems/word-ladder) | Medium |
+| <span id="126">126</span> | [Word Ladder II](https://leetcode.com/problems/word-ladder-ii "单词接龙 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/word-ladder-ii) | Hard |
+| <span id="125">125</span> | [Valid Palindrome](https://leetcode.com/problems/valid-palindrome "验证回文串") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-palindrome) | Easy |
+| <span id="124">124</span> | [Binary Tree Maximum Path Sum](https://leetcode.com/problems/binary-tree-maximum-path-sum "二叉树中的最大路径和") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-maximum-path-sum) | Hard |
+| <span id="123">123</span> | [Best Time to Buy and Sell Stock III](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii "买卖股票的最佳时机 III") | [Go](https://github.com/openset/leetcode/tree/master/problems/best-time-to-buy-and-sell-stock-iii) | Hard |
+| <span id="122">122</span> | [Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii "买卖股票的最佳时机 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/best-time-to-buy-and-sell-stock-ii) | Easy |
+| <span id="121">121</span> | [Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock "买卖股票的最佳时机") | [Go](https://github.com/openset/leetcode/tree/master/problems/best-time-to-buy-and-sell-stock) | Easy |
+| <span id="120">120</span> | [Triangle](https://leetcode.com/problems/triangle "三角形最小路径和") | [Go](https://github.com/openset/leetcode/tree/master/problems/triangle) | Medium |
+| <span id="119">119</span> | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii "杨辉三角 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/pascals-triangle-ii) | Easy |
+| <span id="118">118</span> | [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle "杨辉三角") | [Go](https://github.com/openset/leetcode/tree/master/problems/pascals-triangle) | Easy |
+| <span id="117">117</span> | [Populating Next Right Pointers in Each Node II](https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii "填充同一层的兄弟节点 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/populating-next-right-pointers-in-each-node-ii) | Medium |
+| <span id="116">116</span> | [Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node "填充同一层的兄弟节点") | [Go](https://github.com/openset/leetcode/tree/master/problems/populating-next-right-pointers-in-each-node) | Medium |
+| <span id="115">115</span> | [Distinct Subsequences](https://leetcode.com/problems/distinct-subsequences "不同的子序列") | [Go](https://github.com/openset/leetcode/tree/master/problems/distinct-subsequences) | Hard |
+| <span id="114">114</span> | [Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list "二叉树展开为链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/flatten-binary-tree-to-linked-list) | Medium |
+| <span id="113">113</span> | [Path Sum II](https://leetcode.com/problems/path-sum-ii "路径总和 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/path-sum-ii) | Medium |
+| <span id="112">112</span> | [Path Sum](https://leetcode.com/problems/path-sum "路径总和") | [Go](https://github.com/openset/leetcode/tree/master/problems/path-sum) | Easy |
+| <span id="111">111</span> | [Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree "二叉树的最小深度") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-depth-of-binary-tree) | Easy |
+| <span id="110">110</span> | [Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree "平衡二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/balanced-binary-tree) | Easy |
+| <span id="109">109</span> | [Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree "有序链表转换二叉搜索树") | [Go](https://github.com/openset/leetcode/tree/master/problems/convert-sorted-list-to-binary-search-tree) | Medium |
+| <span id="108">108</span> | [Convert Sorted Array to Binary Search Tree](https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree "将有序数组转换为二叉搜索树") | [Go](https://github.com/openset/leetcode/tree/master/problems/convert-sorted-array-to-binary-search-tree) | Easy |
+| <span id="107">107</span> | [Binary Tree Level Order Traversal II](https://leetcode.com/problems/binary-tree-level-order-traversal-ii "二叉树的层次遍历 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-level-order-traversal-ii) | Easy |
+| <span id="106">106</span> | [Construct Binary Tree from Inorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal "从中序与后序遍历序列构造二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/construct-binary-tree-from-inorder-and-postorder-traversal) | Medium |
+| <span id="105">105</span> | [Construct Binary Tree from Preorder and Inorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal "从前序与中序遍历序列构造二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/construct-binary-tree-from-preorder-and-inorder-traversal) | Medium |
+| <span id="104">104</span> | [Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree "二叉树的最大深度") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-depth-of-binary-tree) | Easy |
+| <span id="103">103</span> | [Binary Tree Zigzag Level Order Traversal](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal "二叉树的锯齿形层次遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-zigzag-level-order-traversal) | Medium |
+| <span id="102">102</span> | [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal "二叉树的层次遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-level-order-traversal) | Medium |
+| <span id="101">101</span> | [Symmetric Tree](https://leetcode.com/problems/symmetric-tree "对称二叉树") | [Go](https://github.com/openset/leetcode/tree/master/problems/symmetric-tree) | Easy |
+| <span id="100">100</span> | [Same Tree](https://leetcode.com/problems/same-tree "相同的树") | [Go](https://github.com/openset/leetcode/tree/master/problems/same-tree) | Easy |
+| <span id="99">99</span> | [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree "恢复二叉搜索树") | [Go](https://github.com/openset/leetcode/tree/master/problems/recover-binary-search-tree) | Hard |
+| <span id="98">98</span> | [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree "验证二叉搜索树") | [Go](https://github.com/openset/leetcode/tree/master/problems/validate-binary-search-tree) | Medium |
+| <span id="97">97</span> | [Interleaving String](https://leetcode.com/problems/interleaving-string "交错字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/interleaving-string) | Hard |
+| <span id="96">96</span> | [Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees "不同的二叉搜索树") | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-binary-search-trees) | Medium |
+| <span id="95">95</span> | [Unique Binary Search Trees II](https://leetcode.com/problems/unique-binary-search-trees-ii "不同的二叉搜索树 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-binary-search-trees-ii) | Medium |
+| <span id="94">94</span> | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal "二叉树的中序遍历") | [Go](https://github.com/openset/leetcode/tree/master/problems/binary-tree-inorder-traversal) | Medium |
+| <span id="93">93</span> | [Restore IP Addresses](https://leetcode.com/problems/restore-ip-addresses "复原IP地址") | [Go](https://github.com/openset/leetcode/tree/master/problems/restore-ip-addresses) | Medium |
+| <span id="92">92</span> | [Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii "反转链表 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-linked-list-ii) | Medium |
+| <span id="91">91</span> | [Decode Ways](https://leetcode.com/problems/decode-ways "解码方法") | [Go](https://github.com/openset/leetcode/tree/master/problems/decode-ways) | Medium |
+| <span id="90">90</span> | [Subsets II](https://leetcode.com/problems/subsets-ii "子集 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/subsets-ii) | Medium |
+| <span id="89">89</span> | [Gray Code](https://leetcode.com/problems/gray-code "格雷编码") | [Go](https://github.com/openset/leetcode/tree/master/problems/gray-code) | Medium |
+| <span id="88">88</span> | [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array "合并两个有序数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/merge-sorted-array) | Easy |
+| <span id="87">87</span> | [Scramble String](https://leetcode.com/problems/scramble-string "扰乱字符串") | [Go](https://github.com/openset/leetcode/tree/master/problems/scramble-string) | Hard |
+| <span id="86">86</span> | [Partition List](https://leetcode.com/problems/partition-list "分隔链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/partition-list) | Medium |
+| <span id="85">85</span> | [Maximal Rectangle](https://leetcode.com/problems/maximal-rectangle "最大矩形") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximal-rectangle) | Hard |
+| <span id="84">84</span> | [Largest Rectangle in Histogram](https://leetcode.com/problems/largest-rectangle-in-histogram "柱状图中最大的矩形") | [Go](https://github.com/openset/leetcode/tree/master/problems/largest-rectangle-in-histogram) | Hard |
+| <span id="83">83</span> | [Remove Duplicates from Sorted List](https://leetcode.com/problems/remove-duplicates-from-sorted-list "删除排序链表中的重复元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-duplicates-from-sorted-list) | Easy |
+| <span id="82">82</span> | [Remove Duplicates from Sorted List II](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii "删除排序链表中的重复元素 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-duplicates-from-sorted-list-ii) | Medium |
+| <span id="81">81</span> | [Search in Rotated Sorted Array II](https://leetcode.com/problems/search-in-rotated-sorted-array-ii "搜索旋转排序数组 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/search-in-rotated-sorted-array-ii) | Medium |
+| <span id="80">80</span> | [Remove Duplicates from Sorted Array II](https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii "删除排序数组中的重复项 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-duplicates-from-sorted-array-ii) | Medium |
+| <span id="79">79</span> | [Word Search](https://leetcode.com/problems/word-search "单词搜索") | [Go](https://github.com/openset/leetcode/tree/master/problems/word-search) | Medium |
+| <span id="78">78</span> | [Subsets](https://leetcode.com/problems/subsets "子集") | [Go](https://github.com/openset/leetcode/tree/master/problems/subsets) | Medium |
+| <span id="77">77</span> | [Combinations](https://leetcode.com/problems/combinations "组合") | [Go](https://github.com/openset/leetcode/tree/master/problems/combinations) | Medium |
+| <span id="76">76</span> | [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring "最小覆盖子串") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-window-substring) | Hard |
+| <span id="75">75</span> | [Sort Colors](https://leetcode.com/problems/sort-colors "颜色分类") | [Go](https://github.com/openset/leetcode/tree/master/problems/sort-colors) | Medium |
+| <span id="74">74</span> | [Search a 2D Matrix](https://leetcode.com/problems/search-a-2d-matrix "搜索二维矩阵") | [Go](https://github.com/openset/leetcode/tree/master/problems/search-a-2d-matrix) | Medium |
+| <span id="73">73</span> | [Set Matrix Zeroes](https://leetcode.com/problems/set-matrix-zeroes "矩阵置零") | [Go](https://github.com/openset/leetcode/tree/master/problems/set-matrix-zeroes) | Medium |
+| <span id="72">72</span> | [Edit Distance](https://leetcode.com/problems/edit-distance "编辑距离") | [Go](https://github.com/openset/leetcode/tree/master/problems/edit-distance) | Hard |
+| <span id="71">71</span> | [Simplify Path](https://leetcode.com/problems/simplify-path "简化路径") | [Go](https://github.com/openset/leetcode/tree/master/problems/simplify-path) | Medium |
+| <span id="70">70</span> | [Climbing Stairs](https://leetcode.com/problems/climbing-stairs "爬楼梯") | [Go](https://github.com/openset/leetcode/tree/master/problems/climbing-stairs) | Easy |
+| <span id="69">69</span> | [Sqrt(x)](https://leetcode.com/problems/sqrtx "x 的平方根") | [Go](https://github.com/openset/leetcode/tree/master/problems/sqrtx) | Easy |
+| <span id="68">68</span> | [Text Justification](https://leetcode.com/problems/text-justification "文本左右对齐") | [Go](https://github.com/openset/leetcode/tree/master/problems/text-justification) | Hard |
+| <span id="67">67</span> | [Add Binary](https://leetcode.com/problems/add-binary "二进制求和") | [Go](https://github.com/openset/leetcode/tree/master/problems/add-binary) | Easy |
+| <span id="66">66</span> | [Plus One](https://leetcode.com/problems/plus-one "加一") | [Go](https://github.com/openset/leetcode/tree/master/problems/plus-one) | Easy |
+| <span id="65">65</span> | [Valid Number](https://leetcode.com/problems/valid-number "有效数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-number) | Hard |
+| <span id="64">64</span> | [Minimum Path Sum](https://leetcode.com/problems/minimum-path-sum "最小路径和") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-path-sum) | Medium |
+| <span id="63">63</span> | [Unique Paths II](https://leetcode.com/problems/unique-paths-ii "不同路径 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-paths-ii) | Medium |
+| <span id="62">62</span> | [Unique Paths](https://leetcode.com/problems/unique-paths "不同路径") | [Go](https://github.com/openset/leetcode/tree/master/problems/unique-paths) | Medium |
+| <span id="61">61</span> | [Rotate List](https://leetcode.com/problems/rotate-list "旋转链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/rotate-list) | Medium |
+| <span id="60">60</span> | [Permutation Sequence](https://leetcode.com/problems/permutation-sequence "第k个排列") | [Go](https://github.com/openset/leetcode/tree/master/problems/permutation-sequence) | Medium |
+| <span id="59">59</span> | [Spiral Matrix II](https://leetcode.com/problems/spiral-matrix-ii "螺旋矩阵 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/spiral-matrix-ii) | Medium |
+| <span id="58">58</span> | [Length of Last Word](https://leetcode.com/problems/length-of-last-word "最后一个单词的长度") | [Go](https://github.com/openset/leetcode/tree/master/problems/length-of-last-word) | Easy |
+| <span id="57">57</span> | [Insert Interval](https://leetcode.com/problems/insert-interval "插入区间") | [Go](https://github.com/openset/leetcode/tree/master/problems/insert-interval) | Hard |
+| <span id="56">56</span> | [Merge Intervals](https://leetcode.com/problems/merge-intervals "合并区间") | [Go](https://github.com/openset/leetcode/tree/master/problems/merge-intervals) | Medium |
+| <span id="55">55</span> | [Jump Game](https://leetcode.com/problems/jump-game "跳跃游戏") | [Go](https://github.com/openset/leetcode/tree/master/problems/jump-game) | Medium |
+| <span id="54">54</span> | [Spiral Matrix](https://leetcode.com/problems/spiral-matrix "螺旋矩阵") | [Go](https://github.com/openset/leetcode/tree/master/problems/spiral-matrix) | Medium |
+| <span id="53">53</span> | [Maximum Subarray](https://leetcode.com/problems/maximum-subarray "最大子序和") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-subarray) | Easy |
+| <span id="52">52</span> | [N-Queens II](https://leetcode.com/problems/n-queens-ii "N皇后 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/n-queens-ii) | Hard |
+| <span id="51">51</span> | [N-Queens](https://leetcode.com/problems/n-queens "N皇后") | [Go](https://github.com/openset/leetcode/tree/master/problems/n-queens) | Hard |
+| <span id="50">50</span> | [Pow(x, n)](https://leetcode.com/problems/powx-n "Pow(x, n)") | [Go](https://github.com/openset/leetcode/tree/master/problems/powx-n) | Medium |
+| <span id="49">49</span> | [Group Anagrams](https://leetcode.com/problems/group-anagrams "字母异位词分组") | [Go](https://github.com/openset/leetcode/tree/master/problems/group-anagrams) | Medium |
+| <span id="48">48</span> | [Rotate Image](https://leetcode.com/problems/rotate-image "旋转图像") | [Go](https://github.com/openset/leetcode/tree/master/problems/rotate-image) | Medium |
+| <span id="47">47</span> | [Permutations II](https://leetcode.com/problems/permutations-ii "全排列 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/permutations-ii) | Medium |
+| <span id="46">46</span> | [Permutations](https://leetcode.com/problems/permutations "全排列") | [Go](https://github.com/openset/leetcode/tree/master/problems/permutations) | Medium |
+| <span id="45">45</span> | [Jump Game II](https://leetcode.com/problems/jump-game-ii "跳跃游戏 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/jump-game-ii) | Hard |
+| <span id="44">44</span> | [Wildcard Matching](https://leetcode.com/problems/wildcard-matching "通配符匹配") | [Go](https://github.com/openset/leetcode/tree/master/problems/wildcard-matching) | Hard |
+| <span id="43">43</span> | [Multiply Strings](https://leetcode.com/problems/multiply-strings "字符串相乘") | [Go](https://github.com/openset/leetcode/tree/master/problems/multiply-strings) | Medium |
+| <span id="42">42</span> | [Trapping Rain Water](https://leetcode.com/problems/trapping-rain-water "接雨水") | [Go](https://github.com/openset/leetcode/tree/master/problems/trapping-rain-water) | Hard |
+| <span id="41">41</span> | [First Missing Positive](https://leetcode.com/problems/first-missing-positive "缺失的第一个正数") | [Go](https://github.com/openset/leetcode/tree/master/problems/first-missing-positive) | Hard |
+| <span id="40">40</span> | [Combination Sum II](https://leetcode.com/problems/combination-sum-ii "组合总和 II") | [Go](https://github.com/openset/leetcode/tree/master/problems/combination-sum-ii) | Medium |
+| <span id="39">39</span> | [Combination Sum](https://leetcode.com/problems/combination-sum "组合总和") | [Go](https://github.com/openset/leetcode/tree/master/problems/combination-sum) | Medium |
+| <span id="38">38</span> | [Count and Say](https://leetcode.com/problems/count-and-say "报数") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-and-say) | Easy |
+| <span id="37">37</span> | [Sudoku Solver](https://leetcode.com/problems/sudoku-solver "解数独") | [Go](https://github.com/openset/leetcode/tree/master/problems/sudoku-solver) | Hard |
+| <span id="36">36</span> | [Valid Sudoku](https://leetcode.com/problems/valid-sudoku "有效的数独") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-sudoku) | Medium |
+| <span id="35">35</span> | [Search Insert Position](https://leetcode.com/problems/search-insert-position "搜索插入位置") | [Go](https://github.com/openset/leetcode/tree/master/problems/search-insert-position) | Easy |
+| <span id="34">34</span> | [Find First and Last Position of Element in Sorted Array](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array "在排序数组中查找元素的第一个和最后一个位置") | [Go](https://github.com/openset/leetcode/tree/master/problems/find-first-and-last-position-of-element-in-sorted-array) | Medium |
+| <span id="33">33</span> | [Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array "搜索旋转排序数组") | [Go](https://github.com/openset/leetcode/tree/master/problems/search-in-rotated-sorted-array) | Medium |
+| <span id="32">32</span> | [Longest Valid Parentheses](https://leetcode.com/problems/longest-valid-parentheses "最长有效括号") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-valid-parentheses) | Hard |
+| <span id="31">31</span> | [Next Permutation](https://leetcode.com/problems/next-permutation "下一个排列") | [Go](https://github.com/openset/leetcode/tree/master/problems/next-permutation) | Medium |
+| <span id="30">30</span> | [Substring with Concatenation of All Words](https://leetcode.com/problems/substring-with-concatenation-of-all-words "串联所有单词的子串") | [Go](https://github.com/openset/leetcode/tree/master/problems/substring-with-concatenation-of-all-words) | Hard |
+| <span id="29">29</span> | [Divide Two Integers](https://leetcode.com/problems/divide-two-integers "两数相除") | [Go](https://github.com/openset/leetcode/tree/master/problems/divide-two-integers) | Medium |
+| <span id="28">28</span> | [Implement strStr()](https://leetcode.com/problems/implement-strstr "实现strStr()") | [Go](https://github.com/openset/leetcode/tree/master/problems/implement-strstr) | Easy |
+| <span id="27">27</span> | [Remove Element](https://leetcode.com/problems/remove-element "移除元素") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-element) | Easy |
+| <span id="26">26</span> | [Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array "删除排序数组中的重复项") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-duplicates-from-sorted-array) | Easy |
+| <span id="25">25</span> | [Reverse Nodes in k-Group](https://leetcode.com/problems/reverse-nodes-in-k-group "k个一组翻转链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-nodes-in-k-group) | Hard |
+| <span id="24">24</span> | [Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs "两两交换链表中的节点") | [Go](https://github.com/openset/leetcode/tree/master/problems/swap-nodes-in-pairs) | Medium |
+| <span id="23">23</span> | [Merge k Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists "合并K个排序链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/merge-k-sorted-lists) | Hard |
+| <span id="22">22</span> | [Generate Parentheses](https://leetcode.com/problems/generate-parentheses "括号生成") | [Go](https://github.com/openset/leetcode/tree/master/problems/generate-parentheses) | Medium |
+| <span id="21">21</span> | [Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists "合并两个有序链表") | [Go](https://github.com/openset/leetcode/tree/master/problems/merge-two-sorted-lists) | Easy |
+| <span id="20">20</span> | [Valid Parentheses](https://leetcode.com/problems/valid-parentheses "有效的括号") | [Go](https://github.com/openset/leetcode/tree/master/problems/valid-parentheses) | Easy |
+| <span id="19">19</span> | [Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list "删除链表的倒数第N个节点") | [Go](https://github.com/openset/leetcode/tree/master/problems/remove-nth-node-from-end-of-list) | Medium |
+| <span id="18">18</span> | [4Sum](https://leetcode.com/problems/4sum "四数之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/4sum) | Medium |
+| <span id="17">17</span> | [Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number "电话号码的字母组合") | [Go](https://github.com/openset/leetcode/tree/master/problems/letter-combinations-of-a-phone-number) | Medium |
+| <span id="16">16</span> | [3Sum Closest](https://leetcode.com/problems/3sum-closest "最接近的三数之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/3sum-closest) | Medium |
+| <span id="15">15</span> | [3Sum](https://leetcode.com/problems/3sum "三数之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/3sum) | Medium |
+| <span id="14">14</span> | [Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix "最长公共前缀") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-common-prefix) | Easy |
+| <span id="13">13</span> | [Roman to Integer](https://leetcode.com/problems/roman-to-integer "罗马数字转整数") | [Go](https://github.com/openset/leetcode/tree/master/problems/roman-to-integer) | Easy |
+| <span id="12">12</span> | [Integer to Roman](https://leetcode.com/problems/integer-to-roman "整数转罗马数字") | [Go](https://github.com/openset/leetcode/tree/master/problems/integer-to-roman) | Medium |
+| <span id="11">11</span> | [Container With Most Water](https://leetcode.com/problems/container-with-most-water "盛最多水的容器") | [Go](https://github.com/openset/leetcode/tree/master/problems/container-with-most-water) | Medium |
+| <span id="10">10</span> | [Regular Expression Matching](https://leetcode.com/problems/regular-expression-matching "正则表达式匹配") | [Go](https://github.com/openset/leetcode/tree/master/problems/regular-expression-matching) | Hard |
+| <span id="9">9</span> | [Palindrome Number](https://leetcode.com/problems/palindrome-number "回文数") | [Go](https://github.com/openset/leetcode/tree/master/problems/palindrome-number) | Easy |
+| <span id="8">8</span> | [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi "字符串转换整数 (atoi)") | [Go](https://github.com/openset/leetcode/tree/master/problems/string-to-integer-atoi) | Medium |
+| <span id="7">7</span> | [Reverse Integer](https://leetcode.com/problems/reverse-integer "整数反转") | [Go](https://github.com/openset/leetcode/tree/master/problems/reverse-integer) | Easy |
+| <span id="6">6</span> | [ZigZag Conversion](https://leetcode.com/problems/zigzag-conversion "Z 字形变换") | [Go](https://github.com/openset/leetcode/tree/master/problems/zigzag-conversion) | Medium |
+| <span id="5">5</span> | [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring "最长回文子串") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-palindromic-substring) | Medium |
+| <span id="4">4</span> | [Median of Two Sorted Arrays](https://leetcode.com/problems/median-of-two-sorted-arrays "寻找两个有序数组的中位数") | [Go](https://github.com/openset/leetcode/tree/master/problems/median-of-two-sorted-arrays) | Hard |
+| <span id="3">3</span> | [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters "无重复字符的最长子串") | [Go](https://github.com/openset/leetcode/tree/master/problems/longest-substring-without-repeating-characters) | Medium |
+| <span id="2">2</span> | [Add Two Numbers](https://leetcode.com/problems/add-two-numbers "两数相加") | [Go](https://github.com/openset/leetcode/tree/master/problems/add-two-numbers) | Medium |
+| <span id="1">1</span> | [Two Sum](https://leetcode.com/problems/two-sum "两数之和") | [Go](https://github.com/openset/leetcode/tree/master/problems/two-sum) | Easy |
diff --git a/internal/base/base.go b/internal/base/base.go
deleted file mode 100644
index 3b1b4451f..000000000
--- a/internal/base/base.go
+++ /dev/null
@@ -1,84 +0,0 @@
-// Package base provides base support.
-package base
-
-import (
-	"bytes"
-	"encoding/json"
-	"fmt"
-	"io/ioutil"
-	"log"
-	"os"
-	"path/filepath"
-	"strings"
-)
-
-// URL - base.URL
-const URL = "https://github.com/awesee/leetcode/tree/main"
-
-// CmdName - base.CmdName
-var CmdName = filepath.Base(os.Args[0])
-
-// Usage - base.Usage
-func Usage() {
-	fmt.Printf("%s is a tool for managing leetcode source code.\n\n", CmdName)
-	fmt.Println("Usage:")
-	fmt.Printf("\t%s <command> [arguments]\n", CmdName)
-	fmt.Println("The commands are:")
-	for _, cmd := range Commands {
-		if !cmd.Hidden {
-			fmt.Printf("\t%-11s \t%s\n", cmd.Name(), cmd.Short)
-		}
-	}
-	fmt.Printf("\nUse \"%s help <command>\" for more information about a command.\n", CmdName)
-}
-
-// FilePutContents - base.FilePutContents
-func FilePutContents(filename string, data []byte) []byte {
-	ext := filepath.Ext(filename)
-	if strings.EqualFold(ext, ".json") {
-		data = JSONIndent(data)
-	}
-	if len(data) > 0 {
-		filename = getFilePath(filename)
-		err := ioutil.WriteFile(filename, data, 0644)
-		CheckErr(err)
-	}
-	return data
-}
-
-// JSONIndent - base.JSONIndent
-func JSONIndent(src []byte) []byte {
-	if !json.Valid(src) {
-		return nil
-	}
-	var buf bytes.Buffer
-	err := json.Indent(&buf, src, "", "\t")
-	CheckErr(err)
-	return buf.Bytes()
-}
-
-// CheckErr - base.CheckErr
-func CheckErr(err error) {
-	if err != nil {
-		log.Fatalln(err)
-	}
-}
-
-// AuthInfo - base.AuthInfo
-func AuthInfo(cmd string) string {
-	format := "<!--|This file generated by command(leetcode %s); DO NOT EDIT.%s|-->\n"
-	format += "<!--+----------------------------------------------------------------------+-->\n"
-	format += "<!--|@author    awesee <openset.wang@gmail.com>                           |-->\n"
-	format += "<!--|@link      https://github.com/awesee                                 |-->\n"
-	format += "<!--|@home      https://github.com/awesee/leetcode                        |-->\n"
-	format += "<!--+----------------------------------------------------------------------+-->\n"
-	return fmt.Sprintf(format, cmd, strings.Repeat(" ", 15-len(cmd)))
-}
-
-func getFilePath(filename string) string {
-	if dir := filepath.Dir(filename); dir != "" {
-		err := os.MkdirAll(dir, 0755)
-		CheckErr(err)
-	}
-	return filename
-}
diff --git a/internal/base/cmd.go b/internal/base/cmd.go
deleted file mode 100644
index fb8dcdc37..000000000
--- a/internal/base/cmd.go
+++ /dev/null
@@ -1,44 +0,0 @@
-package base
-
-import (
-	"fmt"
-	"strings"
-)
-
-// Commands - base.Commands
-var Commands []*Command
-
-// Command - base.Command
-type Command struct {
-	Run       func(cmd *Command, args []string)
-	UsageLine string
-	Short     string
-	Long      string
-	Hidden    bool
-}
-
-// Name - base.Command.Name
-func (c *Command) Name() string {
-	name := c.UsageLine
-	if i := strings.Index(name, " "); i > 0 {
-		name = name[0:i]
-	}
-	return name
-}
-
-// Usage - base.Command.Usage
-func (c *Command) Usage() {
-	fmt.Printf("usage: %s %s\n\n", CmdName, c.UsageLine)
-	fmt.Printf("Run '%s help %s' for details.\n", CmdName, c.Name())
-}
-
-// UsageHelp - base.Command.UsageHelp
-func (c *Command) UsageHelp() {
-	fmt.Printf("usage: %s %s\n\n", CmdName, c.UsageLine)
-	fmt.Println(c.Long)
-}
-
-// Register - base.Register
-func Register(cmds ...*Command) {
-	Commands = append(Commands, cmds...)
-}
diff --git a/internal/base/run.go b/internal/base/run.go
deleted file mode 100644
index f62a66982..000000000
--- a/internal/base/run.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package base
-
-import (
-	"flag"
-	"fmt"
-)
-
-// Run - base.Run
-func Run() {
-	flag.Usage = Usage
-	flag.Parse()
-	if flag.NArg() < 1 {
-		flag.Usage()
-		return
-	}
-	args := flag.Args()
-	cmdName := flag.Arg(0)
-	for _, cmd := range Commands {
-		if cmd.Name() == cmdName {
-			cmd.Run(cmd, args[1:])
-			return
-		}
-	}
-	fmt.Printf("%s %s: unknown command\n\n", CmdName, cmdName)
-	fmt.Printf("Run '%s help' for usage.\n", CmdName)
-}
diff --git a/internal/browser/browser.go b/internal/browser/browser.go
deleted file mode 100644
index 73d527186..000000000
--- a/internal/browser/browser.go
+++ /dev/null
@@ -1,63 +0,0 @@
-// Package browser support open a url in browser.
-package browser
-
-import (
-	"os"
-	"os/exec"
-	"runtime"
-	"time"
-)
-
-// Commands returns a list of possible commands to use to open a url.
-func Commands() [][]string {
-	var cmds [][]string
-	if exe := os.Getenv("BROWSER"); exe != "" {
-		cmds = append(cmds, []string{exe})
-	}
-	switch runtime.GOOS {
-	case "darwin":
-		cmds = append(cmds, []string{"/usr/bin/open"})
-	case "windows":
-		cmds = append(cmds, []string{"cmd", "/c", "start"})
-	default:
-		if os.Getenv("DISPLAY") != "" {
-			// xdg-open is only for use in a desktop environment.
-			cmds = append(cmds, []string{"xdg-open"})
-		}
-	}
-	cmds = append(cmds,
-		[]string{"chrome"},
-		[]string{"google-chrome"},
-		[]string{"chromium"},
-		[]string{"firefox"},
-	)
-	return cmds
-}
-
-// Open tries to open url in a browser and reports whether it succeeded.
-func Open(url string) bool {
-	for _, args := range Commands() {
-		cmd := exec.Command(args[0], append(args[1:], url)...)
-		if cmd.Start() == nil && appearsSuccessful(cmd, 3*time.Second) {
-			return true
-		}
-	}
-	return false
-}
-
-// appearsSuccessful reports whether the command appears to have run successfully.
-// If the command runs longer than the timeout, it's deemed successful.
-// If the command runs within the timeout, it's deemed successful if it exited cleanly.
-func appearsSuccessful(cmd *exec.Cmd, timeout time.Duration) bool {
-	errc := make(chan error, 1)
-	go func() {
-		errc <- cmd.Wait()
-	}()
-
-	select {
-	case <-time.After(timeout):
-		return true
-	case err := <-errc:
-		return err == nil
-	}
-}
diff --git a/internal/build/build.go b/internal/build/build.go
deleted file mode 100644
index 8a7fcdf72..000000000
--- a/internal/build/build.go
+++ /dev/null
@@ -1,81 +0,0 @@
-// Package build implements the command build.
-package build
-
-import (
-	"archive/zip"
-	"fmt"
-	"io"
-	"os"
-	"os/exec"
-	"time"
-
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/version"
-)
-
-// CmdBuild - build.CmdBuild
-var CmdBuild = &base.Command{
-	Run:       runBuild,
-	UsageLine: "build",
-	Short:     "cross compiler",
-	Long:      "compile packages for darwin, windows, linux.",
-	Hidden:    true,
-}
-
-func runBuild(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		cmd.Usage()
-		return
-	}
-	target := map[string][]string{
-		"darwin":  {"amd64"},
-		"windows": {"386", "amd64"},
-		"linux":   {"386", "amd64"},
-	}
-	err := os.Setenv("CGO_ENABLED", "0")
-	base.CheckErr(err)
-	for goos, goarchList := range target {
-		err = os.Setenv("GOOS", goos)
-		base.CheckErr(err)
-		for _, goarch := range goarchList {
-			err = os.Setenv("GOARCH", goarch)
-			base.CheckErr(err)
-			fileName := fmt.Sprintf("%s%s.%s-%s.zip",
-				base.CmdName,
-				version.String(),
-				goos,
-				goarch,
-			)
-			fmt.Println("OS:", goos, "\tArch:", goarch, "\t", fileName)
-			file, err := os.Create(fileName)
-			base.CheckErr(err)
-			zw := zip.NewWriter(file)
-			zf, err := zw.CreateHeader(&zip.FileHeader{
-				Name:     binName(),
-				Method:   zip.Deflate,
-				Modified: time.Now(),
-			})
-			base.CheckErr(err)
-			err = exec.Command("go", "build", "-ldflags", "-s -w", "github.com/awesee/leetcode").Run()
-			base.CheckErr(err)
-			src, err := os.Open(binName())
-			base.CheckErr(err)
-			_, err = io.Copy(zf, src)
-			base.CheckErr(err)
-			err = src.Close()
-			base.CheckErr(err)
-			err = zw.Close()
-			base.CheckErr(err)
-			err = os.Remove(binName())
-			base.CheckErr(err)
-		}
-	}
-}
-
-func binName() string {
-	var exeSuffix string
-	if os.Getenv("GOOS") == "windows" {
-		exeSuffix = ".exe"
-	}
-	return base.CmdName + exeSuffix
-}
diff --git a/internal/clean/clean.go b/internal/clean/clean.go
deleted file mode 100644
index 3d07fd0b6..000000000
--- a/internal/clean/clean.go
+++ /dev/null
@@ -1,23 +0,0 @@
-// Package clean implements the command clean.
-package clean
-
-import (
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/leetcode"
-)
-
-// CmdClean - clean.CmdClean
-var CmdClean = &base.Command{
-	Run:       runClean,
-	UsageLine: "clean",
-	Short:     "remove cached files",
-	Long:      "remove leetcode cached files.",
-}
-
-func runClean(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		cmd.Usage()
-		return
-	}
-	leetcode.Clean()
-}
diff --git a/internal/client/client.go b/internal/client/client.go
deleted file mode 100644
index 9a419e513..000000000
--- a/internal/client/client.go
+++ /dev/null
@@ -1,48 +0,0 @@
-// Package client provides support for http request.
-package client
-
-import (
-	"errors"
-	"io/ioutil"
-	"net/http"
-	"net/http/cookiejar"
-	"strings"
-
-	"github.com/awesee/leetcode/internal/base"
-)
-
-var err error
-
-// Get - client.Get
-func Get(url string) []byte {
-	if resp, err := http.Get(url); err == nil {
-		defer resp.Body.Close()
-		body, err := ioutil.ReadAll(resp.Body)
-		base.CheckErr(err)
-		return body
-	}
-	return nil
-}
-
-// PostJSON - client.PostJSON
-func PostJSON(url, jsonStr string) []byte {
-	if resp, err := http.Post(url, "application/json", strings.NewReader(jsonStr)); err == nil {
-		defer resp.Body.Close()
-		body, err := ioutil.ReadAll(resp.Body)
-		base.CheckErr(err)
-		return body
-	}
-	return nil
-}
-
-func init() {
-	http.DefaultClient.Jar, err = cookiejar.New(nil)
-	base.CheckErr(err)
-	http.DefaultClient.CheckRedirect = func(req *http.Request, via []*http.Request) error {
-		req.Header.Set("Referer", req.URL.String())
-		if len(via) >= 3 {
-			return errors.New("stopped after 3 redirects")
-		}
-		return nil
-	}
-}
diff --git a/internal/description/description.go b/internal/description/description.go
deleted file mode 100644
index 7a71538bf..000000000
--- a/internal/description/description.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Package description implements the command description.
-package description
-
-import (
-	"fmt"
-	"runtime"
-	"sync"
-
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/leetcode"
-)
-
-// CmdDescription - description.CmdDescription
-var CmdDescription = &base.Command{
-	Run:       runDescription,
-	UsageLine: "description",
-	Short:     "build all problems description file",
-	Long:      "build all problems README.md file.",
-	Hidden:    true,
-}
-
-func runDescription(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		cmd.Usage()
-		return
-	}
-	var wg sync.WaitGroup
-	jobs := make(chan leetcode.StatStatusPairsType)
-	for i := 0; i < 1<<runtime.NumCPU(); i++ {
-		go worker(jobs, &wg)
-	}
-	problems := leetcode.ProblemsAll()
-	for _, problem := range problems.StatStatusPairs {
-		fmt.Println(problem.Stat.FrontendQuestionID, "\t"+problem.Stat.QuestionTitle)
-		wg.Add(1)
-		jobs <- problem
-	}
-	wg.Wait()
-}
-
-func worker(jobs <-chan leetcode.StatStatusPairsType, wg *sync.WaitGroup) {
-	for problem := range jobs {
-		titleSlug := problem.Stat.QuestionTitleSlug
-		question := leetcode.QuestionData(titleSlug, false).Data.Question
-		if question.Content == "" && problem.PaidOnly == true && problem.Stat.QuestionArticleLive {
-			question.Content = leetcode.GetDescription(problem.Stat.QuestionArticleSlug)
-		}
-		question.SaveContent()
-		wg.Done()
-	}
-}
diff --git a/internal/help/help.go b/internal/help/help.go
deleted file mode 100644
index cf00dbe93..000000000
--- a/internal/help/help.go
+++ /dev/null
@@ -1,32 +0,0 @@
-// Package help implements the command help.
-package help
-
-import (
-	"fmt"
-
-	"github.com/awesee/leetcode/internal/base"
-)
-
-// CmdHelp - help.CmdHelp
-var CmdHelp = &base.Command{
-	Run:       runHelp,
-	UsageLine: "help [command]",
-	Short:     "show command usage",
-	Long:      "show command usage detail.",
-}
-
-func runHelp(cmd *base.Command, args []string) {
-	if len(args) < 1 {
-		base.Usage()
-		return
-	}
-	cmdName := args[0]
-	for _, cmd := range base.Commands {
-		if cmd.Name() == cmdName {
-			cmd.UsageHelp()
-			return
-		}
-	}
-	fmt.Printf("%s help %s: unknown help topic.\n\n", base.CmdName, cmdName)
-	fmt.Printf("Run '%s help' for usage.\n", base.CmdName)
-}
diff --git a/internal/helper/helper.go b/internal/helper/helper.go
deleted file mode 100644
index b12d1e739..000000000
--- a/internal/helper/helper.go
+++ /dev/null
@@ -1,34 +0,0 @@
-// Package helper implements the command helper.
-package helper
-
-import (
-	"bytes"
-	"os/exec"
-
-	"github.com/awesee/leetcode/internal/base"
-)
-
-// CmdHelper - help.CmdHelper
-var CmdHelper = &base.Command{
-	Run:       runHelper,
-	UsageLine: "helper",
-	Short:     "build helper file",
-	Long:      "build helper README.md file.",
-	Hidden:    true,
-}
-
-func runHelper(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		cmd.Usage()
-		return
-	}
-	var buf bytes.Buffer
-	buf.WriteString(base.AuthInfo("helper"))
-	buf.WriteString("\n# Helper\n\n")
-	buf.WriteString("```text\n")
-	out, err := exec.Command(base.CmdName).Output()
-	base.CheckErr(err)
-	buf.Write(out)
-	buf.WriteString("```\n")
-	base.FilePutContents("helper/README.md", buf.Bytes())
-}
diff --git a/internal/kit/doc.go b/internal/kit/doc.go
deleted file mode 100644
index 8f0b630f8..000000000
--- a/internal/kit/doc.go
+++ /dev/null
@@ -1,2 +0,0 @@
-// Package kit contain the predefined type.
-package kit
diff --git a/internal/kit/is_equal.go b/internal/kit/is_equal.go
deleted file mode 100644
index 3639a2d06..000000000
--- a/internal/kit/is_equal.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package kit
-
-import (
-	"reflect"
-	"sort"
-)
-
-// IsEqualSliceInt returns a boolean
-// reporting whether the slices values
-// are deeply equal in any order.
-func IsEqualSliceInt(s1, s2 []int) bool {
-	sort.Ints(s1)
-	sort.Ints(s2)
-	return reflect.DeepEqual(s1, s2)
-}
diff --git a/internal/kit/is_equal_test.go b/internal/kit/is_equal_test.go
deleted file mode 100644
index 18663da1e..000000000
--- a/internal/kit/is_equal_test.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package kit
-
-import "testing"
-
-func TestIsEqualSliceInt(t *testing.T) {
-	tests := [...]struct {
-		s1       []int
-		s2       []int
-		expected bool
-	}{
-		{
-			s1:       []int{1, 2, 3},
-			s2:       []int{1, 2, 3},
-			expected: true,
-		},
-		{
-			s1:       []int{1, 2, 3},
-			s2:       []int{3, 2, 1},
-			expected: true,
-		},
-		{
-			s1:       []int{1, 2, 3},
-			s2:       []int{1, 2, 1},
-			expected: false,
-		},
-	}
-	for _, tc := range tests {
-		output := IsEqualSliceInt(tc.s1, tc.s2)
-		if output != tc.expected {
-			t.Fatalf("input: %v %v, output: %v, expected: %v", tc.s1, tc.s2, output, tc.expected)
-		}
-	}
-}
diff --git a/internal/kit/list_node.go b/internal/kit/list_node.go
deleted file mode 100644
index 3878aa505..000000000
--- a/internal/kit/list_node.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package kit
-
-// ListNode - Definition for singly-linked list.
-type ListNode struct {
-	Val  int
-	Next *ListNode
-}
-
-// ListNode2SliceInt - convert *ListNode to []int
-func ListNode2SliceInt(l *ListNode) (s []int) {
-	for l != nil {
-		s = append(s, l.Val)
-		l = l.Next
-	}
-	return
-}
-
-// SliceInt2ListNode - convert []int to *ListNode
-func SliceInt2ListNode(s []int) *ListNode {
-	l := &ListNode{}
-	t := l
-	for _, v := range s {
-		t.Next = &ListNode{Val: v}
-		t = t.Next
-	}
-	return l.Next
-}
diff --git a/internal/kit/list_node_test.go b/internal/kit/list_node_test.go
deleted file mode 100644
index 0798c98ef..000000000
--- a/internal/kit/list_node_test.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package kit
-
-import (
-	"reflect"
-	"testing"
-)
-
-func TestListNode(t *testing.T) {
-	tests := [...][]int{
-		{0, 1, 2},
-		{1, 2, 3},
-	}
-	for _, input := range tests {
-		l := SliceInt2ListNode(input)
-		output := ListNode2SliceInt(l)
-		if !reflect.DeepEqual(output, input) {
-			t.Fatalf("input: %v, output: %v, expected: %v", input, output, input)
-		}
-	}
-}
diff --git a/internal/kit/tree_node.go b/internal/kit/tree_node.go
deleted file mode 100644
index 937b8929d..000000000
--- a/internal/kit/tree_node.go
+++ /dev/null
@@ -1,64 +0,0 @@
-package kit
-
-import "math"
-
-// NULL null
-var NULL = math.MinInt32
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode struct {
-	Val   int
-	Left  *TreeNode
-	Right *TreeNode
-}
-
-// SliceInt2TreeNode - convert []int to *TreeNode
-func SliceInt2TreeNode(s []int) *TreeNode {
-	l := len(s)
-	if l == 0 {
-		return nil
-	}
-	tree := &TreeNode{Val: s[0]}
-	node, queue := tree, make([]*TreeNode, 0)
-	for i := 1; i < l; i++ {
-		if s[i] != NULL {
-			node.Left = &TreeNode{Val: s[i]}
-			queue = append(queue, node.Left)
-		}
-		i++
-		if i < l && s[i] != NULL {
-			node.Right = &TreeNode{Val: s[i]}
-			queue = append(queue, node.Right)
-		}
-		if len(queue) > 0 {
-			node = queue[0]
-			queue = queue[1:]
-		} else {
-			break
-		}
-	}
-	return tree
-}
-
-// TreeNode2SliceInt - convert *TreeNode to []int
-func TreeNode2SliceInt(t *TreeNode) (s []int) {
-	if t != nil {
-		queue := []*TreeNode{t}
-		for len(queue) > 0 {
-			if queue[0] != nil {
-				s = append(s, queue[0].Val)
-				if queue[0].Left != nil || queue[0].Right != nil {
-					queue = append(queue, queue[0].Left)
-					queue = append(queue, queue[0].Right)
-				}
-			} else {
-				s = append(s, NULL)
-			}
-			queue = queue[1:]
-		}
-	}
-	for i := len(s) - 1; i >= 0 && s[i] == NULL; i-- {
-		s = s[:i]
-	}
-	return
-}
diff --git a/internal/kit/tree_node_test.go b/internal/kit/tree_node_test.go
deleted file mode 100644
index 15597c851..000000000
--- a/internal/kit/tree_node_test.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package kit
-
-import (
-	"reflect"
-	"testing"
-)
-
-func TestTreeNode(t *testing.T) {
-	tests := [...]struct {
-		input    []int
-		expected []int
-	}{
-		{
-			input:    []int{1, 2, 3, 4},
-			expected: []int{1, 2, 3, 4},
-		},
-		{
-			input:    []int{1, 2, 3, NULL, 5},
-			expected: []int{1, 2, 3, NULL, 5},
-		},
-		{
-			input:    []int{1, 2, 3, NULL, 5, NULL, NULL, NULL},
-			expected: []int{1, 2, 3, NULL, 5},
-		},
-		{
-			input:    nil,
-			expected: nil,
-		},
-	}
-	for _, tc := range tests {
-		output := TreeNode2SliceInt(SliceInt2TreeNode(tc.input))
-		if !reflect.DeepEqual(output, tc.expected) {
-			t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)
-		}
-	}
-}
diff --git a/internal/leetcode/base.go b/internal/leetcode/base.go
deleted file mode 100644
index f53c732ed..000000000
--- a/internal/leetcode/base.go
+++ /dev/null
@@ -1,117 +0,0 @@
-package leetcode
-
-import (
-	"encoding/json"
-	"io/ioutil"
-	"net/http"
-	"net/url"
-	"os"
-	"path/filepath"
-	"strings"
-	"time"
-
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/client"
-)
-
-// leetcode var
-var (
-	authInfo        = base.AuthInfo
-	checkErr        = base.CheckErr
-	filePutContents = base.FilePutContents
-	jsonIndent      = base.JSONIndent
-	LockStr         = " 🔒"
-	translationSet  = make(map[int]string)
-	titleSlugID     = make(map[string]int)
-)
-
-// Clean - leetcode.Clean
-func Clean() {
-	dir := getCachePath("")
-	err := os.RemoveAll(dir)
-	checkErr(err)
-}
-
-func graphQLRequest(graphQL, jsonStr, filename string, days int, v interface{}) {
-	data := remember(filename, days, func() []byte {
-		return client.PostJSON(graphQL, jsonStr)
-	})
-	jsonDecode(data, &v)
-}
-
-func remember(filename string, days int, f func() []byte) []byte {
-	filename = getCachePath(filename)
-	if fi, err := os.Stat(filename); err == nil {
-		t := fi.ModTime().AddDate(0, 0, days)
-		if time.Now().Add(time.Duration(t.Unix()%86400) * time.Second).Before(t) {
-			return fileGetContents(filename)
-		} else if cts := f(); len(cts) == 0 {
-			return fileGetContents(filename)
-		} else {
-			return filePutContents(filename, cts)
-		}
-	}
-	return filePutContents(filename, f())
-}
-
-func getCsrfToken(cookies []*http.Cookie) string {
-	for _, cookie := range cookies {
-		if cookie.Name == "csrftoken" {
-			return cookie.Value
-		}
-	}
-	return ""
-}
-
-func getCachePath(f string) string {
-	dir, err := os.UserHomeDir()
-	if err != nil {
-		dir, err = os.UserCacheDir()
-		checkErr(err)
-	}
-	return filepath.Join(dir, ".leetcode", f)
-}
-
-func fileGetContents(filename string) []byte {
-	if cts, err := ioutil.ReadFile(filename); err == nil {
-		return cts
-	}
-	return nil
-}
-
-func jsonEncode(v interface{}) []byte {
-	data, err := json.Marshal(v)
-	checkErr(err)
-	return jsonIndent(data)
-}
-
-func jsonDecode(data []byte, v interface{}) {
-	if len(data) > 0 {
-		err := json.Unmarshal(data, v)
-		checkErr(err)
-	}
-}
-
-func saveCookies(cookies []*http.Cookie) {
-	filePutContents(getCachePath(cookiesFile), jsonEncode(cookies))
-}
-
-func getCookies() (cookies []*http.Cookie) {
-	cts := fileGetContents(getCachePath(cookiesFile))
-	jsonDecode(cts, &cookies)
-	return
-}
-
-func saveCredential(data url.Values) {
-	filePutContents(getCachePath(credentialsFile), jsonEncode(data))
-}
-
-func getCredential() (data url.Values) {
-	cts := fileGetContents(getCachePath(credentialsFile))
-	jsonDecode(cts, &data)
-	return
-}
-
-func slugToSnake(slug string) string {
-	return strings.ReplaceAll(slug, "-", "_")
-}
diff --git a/internal/leetcode/config.go b/internal/leetcode/config.go
deleted file mode 100644
index b0c6aceb9..000000000
--- a/internal/leetcode/config.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package leetcode
-
-// leetcode const
-const (
-	accountsLoginURL         = "https://leetcode.com/accounts/login/"
-	apiProblemsAllURL        = "https://leetcode.com/api/problems/all/"
-	apiProblemsAlgorithmsURL = "https://leetcode.com/api/problems/algorithms/"
-	apiProblemsDatabaseURL   = "https://leetcode.com/api/problems/database/"
-	apiProblemsShellURL      = "https://leetcode.com/api/problems/shell/"
-	problemsetAllURL         = "https://leetcode.com/problemset/all/"
-	questionArticleURL       = "https://leetcode.com/articles/%s/"
-	graphQLUrl               = "https://leetcode.com/graphql"
-	graphQLCnURL             = "https://leetcode-cn.com/graphql"
-	apiProgressAllURL        = "https://leetcode.com/api/progress/all/"
-	submissionsLatestURL     = "https://leetcode.com/submissions/latest/"
-)
-
-const (
-	cookiesFile             = "cookies.json"
-	credentialsFile         = "credentials.json"
-	problemsetAllFile       = "problemset_all.html"
-	problemsAllFile         = "problems_all.json"
-	problemsAlgorithmsFile  = "problems_algorithms.json"
-	problemsDatabaseFile    = "problems_database.json"
-	problemsShellFile       = "problems_shell.json"
-	questionTranslationFile = "question_translation.json"
-	questionDataFile        = "question_data_%s.json"
-	questionArticleFile     = "question_article_%s.html"
-	topicTagFile            = "topic_tag_%s.json"
-)
diff --git a/internal/leetcode/doc.go b/internal/leetcode/doc.go
deleted file mode 100644
index 77d4a5503..000000000
--- a/internal/leetcode/doc.go
+++ /dev/null
@@ -1,2 +0,0 @@
-// Package leetcode implements access to leetcode.com.
-package leetcode
diff --git a/internal/leetcode/lang_kit.go b/internal/leetcode/lang_kit.go
deleted file mode 100644
index 02c2a2f84..000000000
--- a/internal/leetcode/lang_kit.go
+++ /dev/null
@@ -1,22 +0,0 @@
-package leetcode
-
-var langSet = make(map[string]string)
-
-func saveAsMySQL(titleSlug string) {
-	langSet[titleSlug] = "MySQL"
-}
-
-func isLangMySQL(titleSlug string) bool {
-	return langSet[titleSlug] == "MySQL"
-}
-
-func saveAsBash(titleSlug string) {
-	langSet[titleSlug] = "Bash"
-}
-
-func getLang(titleSlug string) string {
-	if lang, ok := langSet[titleSlug]; ok {
-		return lang
-	}
-	return "Go"
-}
diff --git a/internal/leetcode/login.go b/internal/leetcode/login.go
deleted file mode 100644
index f7f0d834c..000000000
--- a/internal/leetcode/login.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package leetcode
-
-import (
-	"fmt"
-	"net/http"
-	"net/url"
-)
-
-// AccountsLogin - leetcode.AccountsLogin
-func AccountsLogin(username, password string) (*http.Response, error) {
-	resp, err := http.Head(accountsLoginURL)
-	checkErr(err)
-	defer resp.Body.Close()
-	saveCookies(resp.Cookies())
-	csrftoken := getCsrfToken(resp.Cookies())
-	data := url.Values{
-		"login":               {username},
-		"password":            {password},
-		"csrfmiddlewaretoken": {csrftoken},
-	}
-	resp, err = http.PostForm(accountsLoginURL, data)
-	checkErr(err)
-	defer resp.Body.Close()
-	saveCookies(resp.Cookies())
-	if resp.StatusCode == 200 {
-		saveCredential(data)
-	} else {
-		fmt.Println("login error: ", resp.Status)
-	}
-	return resp, err
-}
-
-// AutoLogin - leetcode.AutoLogin
-func AutoLogin() (*http.Response, error) {
-	data := getCredential()
-	if data.Get("login") == "" {
-		fmt.Println("can't get username")
-	}
-	if data.Get("password") == "" {
-		fmt.Println("can't get password")
-	}
-	return AccountsLogin(data.Get("login"), data.Get("password"))
-}
diff --git a/internal/leetcode/problems_algorithms.go b/internal/leetcode/problems_algorithms.go
deleted file mode 100644
index cde634476..000000000
--- a/internal/leetcode/problems_algorithms.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package leetcode
-
-import "github.com/awesee/leetcode/internal/client"
-
-// ProblemsAlgorithms - leetcode.ProblemsAlgorithms
-func ProblemsAlgorithms() (ps ProblemsType) {
-	data := remember(problemsAlgorithmsFile, 2, func() []byte {
-		return client.Get(apiProblemsAlgorithmsURL)
-	})
-	jsonDecode(data, &ps)
-	return
-}
diff --git a/internal/leetcode/problems_all.go b/internal/leetcode/problems_all.go
deleted file mode 100644
index 86248b591..000000000
--- a/internal/leetcode/problems_all.go
+++ /dev/null
@@ -1,120 +0,0 @@
-package leetcode
-
-import (
-	"bytes"
-	"fmt"
-	"sort"
-	"strings"
-
-	"github.com/awesee/leetcode/internal/client"
-)
-
-// ProblemsType - leetcode.ProblemsType
-type ProblemsType struct {
-	UserName        string                `json:"user_name"`
-	NumSolved       int                   `json:"num_solved"`
-	NumTotal        int                   `json:"num_total"`
-	AcEasy          int                   `json:"ac_easy"`
-	AcMedium        int                   `json:"ac_medium"`
-	AcHard          int                   `json:"ac_hard"`
-	StatStatusPairs []StatStatusPairsType `json:"stat_status_pairs"`
-	FrequencyHigh   int                   `json:"frequency_high"`
-	FrequencyMid    int                   `json:"frequency_mid"`
-	CategorySlug    string                `json:"category_slug"`
-}
-
-// StatStatusPairsType - leetcode.StatStatusPairsType
-type StatStatusPairsType struct {
-	Stat       statType       `json:"stat"`
-	Status     string         `json:"status"`
-	Difficulty difficultyType `json:"difficulty"`
-	PaidOnly   paidType       `json:"paid_only"`
-	IsFavor    bool           `json:"is_favor"`
-	Frequency  int            `json:"frequency"`
-	Progress   int            `json:"progress"`
-}
-
-// WriteRow - leetcode.WriteRow
-func (problem *StatStatusPairsType) WriteRow(buf *bytes.Buffer, path string) {
-	format := "| <span id=\"%d\">%d</span> | [%s](https://leetcode.com/problems/%s%s)%s | [%s](%s/%s) | %s |\n"
-	id := problem.Stat.FrontendQuestionID
-	stat := problem.Stat
-	title := strings.TrimSpace(problem.Stat.QuestionTitle)
-	titleSlug := stat.QuestionTitleSlug
-	levelName := problem.Difficulty.LevelName()
-	buf.WriteString(fmt.Sprintf(format, id, id,
-		title, titleSlug, stat.TranslationTitle(), problem.PaidOnly.Str(),
-		stat.Lang(), path, titleSlug,
-		levelName,
-	))
-}
-
-type statType struct {
-	QuestionID          int    `json:"question_id"`
-	QuestionArticleLive bool   `json:"question__article__live"`
-	QuestionArticleSlug string `json:"question__article__slug"`
-	QuestionTitle       string `json:"question__title"`
-	QuestionTitleSlug   string `json:"question__title_slug"`
-	QuestionHide        bool   `json:"question__hide"`
-	TotalAcs            int    `json:"total_acs"`
-	TotalSubmitted      int    `json:"total_submitted"`
-	FrontendQuestionID  int    `json:"frontend_question_id"`
-	IsNewQuestion       bool   `json:"is_new_question"`
-}
-
-func (s *statType) Lang() string {
-	return getLang(s.QuestionTitleSlug)
-}
-
-func (s *statType) QuestionTitleSnake() string {
-	return slugToSnake(s.QuestionTitleSlug)
-}
-
-func (s *statType) TranslationTitle() string {
-	title := translationSet[s.QuestionID]
-	if title != "" {
-		title = fmt.Sprintf(` "%s"`, title)
-	}
-	return title
-}
-
-type difficultyType struct {
-	Level int `json:"level"`
-}
-
-func (d *difficultyType) LevelName() string {
-	m := map[int]string{
-		1: "Easy",
-		2: "Medium",
-		3: "Hard",
-	}
-	return m[d.Level]
-}
-
-type paidType bool
-
-func (p paidType) Str() string {
-	if p {
-		return LockStr
-	}
-	return ""
-}
-
-// ProblemsAll - leetcode.ProblemsAll
-func ProblemsAll() (ps ProblemsType) {
-	data := remember(problemsAllFile, 2, func() []byte {
-		return client.Get(apiProblemsAllURL)
-	})
-	jsonDecode(data, &ps)
-	sort.Slice(ps.StatStatusPairs, func(i, j int) bool {
-		return ps.StatStatusPairs[i].Stat.FrontendQuestionID > ps.StatStatusPairs[j].Stat.FrontendQuestionID
-	})
-	return
-}
-
-func init() {
-	questions := ProblemsAll().StatStatusPairs
-	for _, item := range questions {
-		titleSlugID[item.Stat.QuestionTitleSlug] = item.Stat.FrontendQuestionID
-	}
-}
diff --git a/internal/leetcode/problems_database.go b/internal/leetcode/problems_database.go
deleted file mode 100644
index c2495a9b0..000000000
--- a/internal/leetcode/problems_database.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package leetcode
-
-import "github.com/awesee/leetcode/internal/client"
-
-// ProblemsDatabase - leetcode.ProblemsDatabase
-func ProblemsDatabase() (ps ProblemsType) {
-	data := remember(problemsDatabaseFile, 2, func() []byte {
-		return client.Get(apiProblemsDatabaseURL)
-	})
-	jsonDecode(data, &ps)
-	return
-}
-
-func init() {
-	problems := ProblemsDatabase()
-	for _, problem := range problems.StatStatusPairs {
-		saveAsMySQL(problem.Stat.QuestionTitleSlug)
-	}
-}
diff --git a/internal/leetcode/problems_shell.go b/internal/leetcode/problems_shell.go
deleted file mode 100644
index 5714429de..000000000
--- a/internal/leetcode/problems_shell.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package leetcode
-
-import "github.com/awesee/leetcode/internal/client"
-
-// ProblemsShell - leetcode.ProblemsShell
-func ProblemsShell() (ps ProblemsType) {
-	data := remember(problemsShellFile, 2, func() []byte {
-		return client.Get(apiProblemsShellURL)
-	})
-	jsonDecode(data, &ps)
-	return
-}
-
-func init() {
-	problems := ProblemsShell()
-	for _, problem := range problems.StatStatusPairs {
-		saveAsBash(problem.Stat.QuestionTitleSlug)
-	}
-}
diff --git a/internal/leetcode/problems_status.go b/internal/leetcode/problems_status.go
deleted file mode 100644
index 11f8d115b..000000000
--- a/internal/leetcode/problems_status.go
+++ /dev/null
@@ -1,249 +0,0 @@
-package leetcode
-
-var problemStatus = map[int]bool{
-	1:    true,
-	2:    true,
-	3:    true,
-	4:    true,
-	5:    true,
-	6:    true,
-	7:    true,
-	8:    true,
-	9:    true,
-	10:   true,
-	11:   true,
-	12:   true,
-	13:   true,
-	14:   true,
-	15:   true,
-	16:   true,
-	17:   true,
-	18:   true,
-	19:   true,
-	20:   true,
-	21:   true,
-	22:   true,
-	24:   true,
-	26:   true,
-	27:   true,
-	28:   true,
-	32:   true,
-	35:   true,
-	36:   true,
-	38:   true,
-	48:   true,
-	50:   true,
-	53:   true,
-	58:   true,
-	65:   true,
-	66:   true,
-	67:   true,
-	69:   true,
-	70:   true,
-	71:   true,
-	83:   true,
-	88:   true,
-	100:  true,
-	101:  true,
-	104:  true,
-	108:  true,
-	110:  true,
-	112:  true,
-	118:  true,
-	119:  true,
-	121:  true,
-	122:  true,
-	125:  true,
-	136:  true,
-	137:  true,
-	139:  true,
-	141:  true,
-	151:  true,
-	155:  true,
-	160:  true,
-	165:  true,
-	167:  true,
-	168:  true,
-	169:  true,
-	171:  true,
-	172:  true,
-	182:  true,
-	189:  true,
-	190:  true,
-	191:  true,
-	192:  true,
-	193:  true,
-	194:  true,
-	195:  true,
-	198:  true,
-	202:  true,
-	204:  true,
-	206:  true,
-	215:  true,
-	217:  true,
-	219:  true,
-	226:  true,
-	231:  true,
-	233:  true,
-	234:  true,
-	237:  true,
-	242:  true,
-	258:  true,
-	263:  true,
-	264:  true,
-	268:  true,
-	283:  true,
-	290:  true,
-	292:  true,
-	303:  true,
-	319:  true,
-	326:  true,
-	342:  true,
-	343:  true,
-	344:  true,
-	345:  true,
-	350:  true,
-	367:  true,
-	371:  true,
-	383:  true,
-	387:  true,
-	393:  true,
-	412:  true,
-	413:  true,
-	414:  true,
-	415:  true,
-	434:  true,
-	437:  true,
-	441:  true,
-	443:  true,
-	445:  true,
-	448:  true,
-	453:  true,
-	455:  true,
-	459:  true,
-	461:  true,
-	468:  true,
-	485:  true,
-	504:  true,
-	509:  true,
-	520:  true,
-	521:  true,
-	532:  true,
-	541:  true,
-	551:  true,
-	557:  true,
-	561:  true,
-	565:  true,
-	566:  true,
-	581:  true,
-	595:  true,
-	605:  true,
-	606:  true,
-	617:  true,
-	620:  true,
-	626:  true,
-	627:  true,
-	628:  true,
-	643:  true,
-	657:  true,
-	661:  true,
-	665:  true,
-	674:  true,
-	679:  true,
-	680:  true,
-	686:  true,
-	696:  true,
-	697:  true,
-	705:  true,
-	706:  true,
-	709:  true,
-	717:  true,
-	724:  true,
-	728:  true,
-	744:  true,
-	746:  true,
-	747:  true,
-	766:  true,
-	771:  true,
-	788:  true,
-	793:  true,
-	796:  true,
-	804:  true,
-	819:  true,
-	824:  true,
-	830:  true,
-	832:  true,
-	840:  true,
-	849:  true,
-	859:  true,
-	867:  true,
-	877:  true,
-	888:  true,
-	893:  true,
-	896:  true,
-	905:  true,
-	908:  true,
-	912:  true,
-	914:  true,
-	917:  true,
-	922:  true,
-	925:  true,
-	929:  true,
-	933:  true,
-	937:  true,
-	938:  true,
-	941:  true,
-	942:  true,
-	944:  true,
-	949:  true,
-	953:  true,
-	961:  true,
-	965:  true,
-	970:  true,
-	973:  true,
-	976:  true,
-	977:  true,
-	984:  true,
-	985:  true,
-	989:  true,
-	993:  true,
-	994:  true,
-	997:  true,
-	999:  true,
-	1000: true,
-	1002: true,
-	1005: true,
-	1009: true,
-	1010: true,
-	1013: true,
-	1018: true,
-	1021: true,
-	1022: true,
-	1023: true,
-	1025: true,
-	1029: true,
-	1037: true,
-	1041: true,
-	1042: true,
-	1046: true,
-	1047: true,
-	1051: true,
-	1071: true,
-	1108: true,
-	1154: true,
-	1163: true,
-	1170: true,
-	1185: true,
-	1189: true,
-	1221: true,
-	1408: true,
-	1417: true,
-	1422: true,
-	1436: true,
-	1455: true,
-}
-
-// IsSolved - leetcode.IsSolved
-func IsSolved(id int) bool {
-	return problemStatus[id]
-}
diff --git a/internal/leetcode/question_article.go b/internal/leetcode/question_article.go
deleted file mode 100644
index ece22475f..000000000
--- a/internal/leetcode/question_article.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package leetcode
-
-import (
-	"bytes"
-	"fmt"
-	"regexp"
-
-	"github.com/awesee/leetcode/internal/client"
-)
-
-// GetDescription - leetcode.GetDescription
-func GetDescription(articleSlug string) string {
-	filename := fmt.Sprintf(questionArticleFile, slugToSnake(articleSlug))
-	html := remember(filename, 6, func() []byte {
-		return client.Get(fmt.Sprintf(questionArticleURL, articleSlug))
-	})
-	reg := regexp.MustCompile(`<div class="block-markdown question">([\S\s]+?)</div>`)
-	matches := reg.FindSubmatch(html)
-	if len(matches) >= 2 {
-		return string(bytes.TrimSpace(matches[1]))
-	}
-	return ""
-}
diff --git a/internal/leetcode/question_data.go b/internal/leetcode/question_data.go
deleted file mode 100644
index a326f54cc..000000000
--- a/internal/leetcode/question_data.go
+++ /dev/null
@@ -1,382 +0,0 @@
-package leetcode
-
-import (
-	"bytes"
-	"fmt"
-	"log"
-	"os"
-	"path/filepath"
-	"regexp"
-	"strconv"
-	"strings"
-)
-
-const testTpl = `package {{packageName}}
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func Test{{funcName}}(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   0,
-			want: 0,
-		},
-	}
-	for _, tt := range tests {
-		got := 0
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
-`
-
-// QuestionDataType - leetcode.QuestionDataType
-type QuestionDataType struct {
-	Errors []errorType `json:"errors"`
-	Data   dataType    `json:"data"`
-}
-
-type errorType struct {
-	Message string `json:"message"`
-}
-
-type dataType struct {
-	Question questionType `json:"question"`
-}
-
-type questionType struct {
-	QuestionID         string             `json:"questionId"`
-	QuestionFrontendID string             `json:"questionFrontendId"`
-	BoundTopicID       int                `json:"boundTopicId"`
-	Title              string             `json:"title"`
-	TitleSlug          string             `json:"titleSlug"`
-	Content            string             `json:"content"`
-	TranslatedTitle    string             `json:"translatedTitle"`
-	TranslatedContent  string             `json:"translatedContent"`
-	IsPaidOnly         paidType           `json:"isPaidOnly"`
-	Difficulty         difficultyStrType  `json:"difficulty"`
-	Likes              int                `json:"likes"`
-	Dislikes           int                `json:"dislikes"`
-	IsLiked            int                `json:"isLiked"`
-	SimilarQuestions   string             `json:"similarQuestions"`
-	TopicTags          []TagType          `json:"topicTags"`
-	CodeSnippets       []codeSnippetsType `json:"codeSnippets"`
-	Hints              []string           `json:"hints"`
-	MysqlSchemas       []string           `json:"mysqlSchemas"`
-}
-
-func (question *questionType) SaveContent() {
-	if question.TitleSlug != "" {
-		filePutContents(question.getFilePath("README.md"), question.getDescContent())
-		question.saveMysqlSchemas()
-	}
-}
-
-func (question *questionType) GetSimilarQuestion() (sq []similarQuestionType) {
-	jsonDecode([]byte(question.SimilarQuestions), &sq)
-	return
-}
-
-func (question *questionType) TitleSnake() string {
-	return slugToSnake(question.TitleSlug)
-}
-
-func (question *questionType) LeetCodeURL() string {
-	return "https://leetcode.com/problems/" + question.TitleSlug
-}
-
-func (question *questionType) PackageName() string {
-	return fmt.Sprintf("problem%d", question.FrontendID())
-}
-
-func (question *questionType) SaveCodeSnippet() {
-	if isLangMySQL(question.TitleSlug) {
-		filePutContents(question.getFilePath(question.TitleSnake()+".sql"), []byte("# Write your MySQL query statement below\n"))
-	}
-	langSupport := [...]struct {
-		slug   string
-		handle func(*questionType, codeSnippetsType)
-	}{
-		{"golang", handleCodeGolang},
-		{"python3", handleCodePython},
-		{"python", handleCodePython},
-		{"bash", handleCodeBash},
-		{"mysql", handleCodeSQL},
-		{"mssql", handleCodeSQL},
-		{"oraclesql", handleCodeSQL},
-	}
-	codeSet := make(map[string]codeSnippetsType)
-	for _, code := range question.CodeSnippets {
-		codeSet[code.LangSlug] = code
-	}
-	for _, lang := range langSupport {
-		if code, ok := codeSet[lang.slug]; ok {
-			lang.handle(question, code)
-			return
-		}
-	}
-}
-
-func (question *questionType) getDescContent() []byte {
-	var buf bytes.Buffer
-	buf.WriteString(authInfo("description"))
-	buf.WriteString(question.getNavigation())
-	buf.WriteString(fmt.Sprintf("\n## [%d. %s%s](%s \"%s\")\n\n",
-		question.FrontendID(),
-		question.Title,
-		question.Difficulty.Str(),
-		question.LeetCodeURL(),
-		question.translatedTitle(),
-	))
-	cts := filterContents(question.Content)
-	// remove style
-	reg := regexp.MustCompile(`<style[\S\s]+?</style>`)
-	cts = reg.ReplaceAllString(cts, "")
-	cts = strings.ReplaceAll(cts, "\n\n\t", "\n\t")
-	cts = strings.TrimSpace(cts) + "\n"
-	buf.WriteString(cts)
-	buf.Write(question.getTopicTags())
-	buf.Write(question.getSimilarQuestion())
-	buf.Write(question.getHints())
-	return buf.Bytes()
-}
-
-func (question *questionType) questionID() int {
-	id, _ := strconv.Atoi(question.QuestionID)
-	return id
-}
-
-func (question *questionType) FrontendID() int {
-	id := titleSlugID[question.TitleSlug]
-	if id != 0 {
-		return id
-	}
-	id, _ = strconv.Atoi(question.QuestionFrontendID)
-	return id
-}
-
-func (question *questionType) translatedTitle() string {
-	if question.TranslatedTitle == "" {
-		question.TranslatedTitle = translationSet[question.questionID()]
-	}
-	return question.TranslatedTitle
-}
-
-func (question *questionType) getNavigation() string {
-	nav, pre, next := "\n%s\n%s\n%s\n", "< Previous", "Next >"
-	problems := ProblemsAll().StatStatusPairs
-	id := question.questionID()
-	format := `[%s](../%s "%s")`
-	for i, problem := range problems {
-		if problem.Stat.QuestionID == id {
-			if i < len(problems)-1 {
-				pre = fmt.Sprintf(format, pre, problems[i+1].Stat.QuestionTitleSlug, problems[i+1].Stat.QuestionTitle)
-			}
-			if i > 0 {
-				next = fmt.Sprintf(format, next, problems[i-1].Stat.QuestionTitleSlug, problems[i-1].Stat.QuestionTitle)
-			}
-			break
-		}
-	}
-	return fmt.Sprintf(nav, pre, strings.Repeat("　", 16), next)
-}
-
-func (question *questionType) getTopicTags() []byte {
-	tags := question.TopicTags
-	var buf bytes.Buffer
-	if len(tags) > 0 {
-		buf.WriteString("\n### Related Topics\n")
-	}
-	format := "  [[%s](../../tag/%s/README.md)]\n"
-	for _, tag := range tags {
-		buf.WriteString(fmt.Sprintf(format, tag.Name, tag.Slug))
-	}
-	return buf.Bytes()
-}
-
-func (question *questionType) getHints() []byte {
-	hints := question.Hints
-	var buf bytes.Buffer
-	if len(hints) > 0 {
-		buf.WriteString("\n### Hints")
-	}
-	for i, hint := range hints {
-		buf.WriteString(fmt.Sprintf("\n<details>\n<summary>Hint %d</summary>\n%s\n</details>\n", i+1, filterContents(hint)))
-	}
-	return buf.Bytes()
-}
-
-func (question *questionType) RenamePackageName() {
-	packageName := fmt.Sprintf("package %s", question.PackageName())
-	reg := regexp.MustCompile(`package \w+`)
-	for _, ext := range [...]string{".go", "_test.go"} {
-		cts := fileGetContents(question.getFilePath(question.TitleSnake() + ext))
-		if len(cts) > 0 {
-			content := reg.ReplaceAllString(string(cts), packageName)
-			question.saveCodeContent(content, ext)
-		}
-	}
-}
-
-func (question *questionType) Restore() {
-	filename := question.getFilePath("README.md")
-	body := fileGetContents(filename)
-	pattern := `## [^\n]+\n\n([\S\s]+)`
-	if bytes.Contains(body, []byte("\n### ")) {
-		pattern = `## [^\n]+\n\n([\S\s]+?)\n### `
-	}
-	reg := regexp.MustCompile(pattern)
-	matches := reg.FindSubmatch(body)
-	if len(matches) < 2 {
-		return
-	}
-	question.Content = string(bytes.TrimSpace(matches[1]))
-	name := fmt.Sprintf(questionDataFile, question.TitleSnake())
-	filePutContents(getCachePath(name), jsonEncode(QuestionDataType{
-		Data: dataType{Question: *question},
-	}))
-}
-
-func (question *questionType) getSimilarQuestion() []byte {
-	sq := question.GetSimilarQuestion()
-	var buf bytes.Buffer
-	if len(sq) > 0 {
-		buf.WriteString("\n### Similar Questions\n")
-	}
-	format := "  1. [%s](../%s)%s\n"
-	for _, q := range sq {
-		buf.WriteString(fmt.Sprintf(format, q.Title, q.TitleSlug, q.Difficulty.Str()))
-	}
-	return buf.Bytes()
-}
-
-func (question *questionType) getFilePath(filename string) string {
-	return filepath.Join("problems", question.TitleSlug, filename)
-}
-
-func (question *questionType) saveCodeContent(content, ext string, permX ...bool) {
-	filePath := question.getFilePath(question.TitleSnake() + ext)
-	filePutContents(filePath, []byte(content))
-	if len(permX) > 0 && permX[0] {
-		_ = os.Chmod(filePath, 0755)
-	}
-}
-
-func (question *questionType) saveMysqlSchemas() {
-	var buf bytes.Buffer
-	for _, s := range question.MysqlSchemas {
-		buf.WriteString(s + ";\n")
-	}
-	filePutContents(question.getFilePath("mysql_schemas.sql"), buf.Bytes())
-}
-
-type codeSnippetsType struct {
-	Lang     string `json:"lang"`
-	LangSlug string `json:"langSlug"`
-	Code     string `json:"code"`
-}
-
-type similarQuestionType struct {
-	Title           string            `json:"title"`
-	TitleSlug       string            `json:"titleSlug"`
-	Difficulty      difficultyStrType `json:"difficulty"`
-	TranslatedTitle string            `json:"translatedTitle"`
-}
-
-type difficultyStrType string
-
-func (d difficultyStrType) Str() (s string) {
-	if d != "" {
-		s = fmt.Sprintf(" (%s)", d)
-	}
-	return
-}
-
-// QuestionData - leetcode.QuestionData
-func QuestionData(titleSlug string, isForce bool, graphQL ...string) (qd QuestionDataType) {
-	jsonStr := `{
-		"operationName": "questionData",
-		"variables": {
-			"titleSlug": "` + titleSlug + `"
-		},
-		"query": "query questionData($titleSlug: String!) {\n  question(titleSlug: $titleSlug) {\n    questionId\n    questionFrontendId\n    boundTopicId\n    title\n    titleSlug\n    content\n    translatedTitle\n    translatedContent\n    isPaidOnly\n    difficulty\n    likes\n    dislikes\n    isLiked\n    similarQuestions\n    contributors {\n      username\n      profileUrl\n      avatarUrl\n      __typename\n    }\n    langToValidPlayground\n    topicTags {\n      name\n      slug\n      translatedName\n      __typename\n    }\n    companyTagStats\n    codeSnippets {\n      lang\n      langSlug\n      code\n      __typename\n    }\n    stats\n    hints\n    solution {\n      id\n      canSeeDetail\n      __typename\n    }\n    status\n    sampleTestCase\n    metaData\n    judgerAvailable\n    judgeType\n    mysqlSchemas\n    enableRunCode\n    enableTestMode\n    envInfo\n    __typename\n  }\n}\n"
-	}`
-	days := 3
-	if isForce {
-		days = 0
-	}
-	if len(graphQL) == 0 {
-		graphQL = []string{graphQLCnURL}
-	}
-	name := fmt.Sprintf(questionDataFile, slugToSnake(titleSlug))
-	filename := getCachePath(name)
-	oldContent := getContent(filename)
-	graphQLRequest(graphQL[0], jsonStr, name, days, &qd)
-	if qd.Data.Question.Content == "" && oldContent != "" {
-		qd.Data.Question.Content = oldContent
-		filePutContents(filename, jsonEncode(qd))
-	}
-	if qd.Data.Question.TitleSlug == "" {
-		if graphQL[0] == graphQLCnURL {
-			return QuestionData(titleSlug, true, graphQLUrl)
-		}
-		for _, err := range qd.Errors {
-			log.Println(titleSlug, err.Message)
-		}
-	}
-	return
-}
-
-func handleCodeGolang(question *questionType, code codeSnippetsType) {
-	content := fmt.Sprintf("package %s\n\n", question.PackageName())
-	content += code.Code + "\n"
-	question.saveCodeContent(content, ".go")
-	testExt := "_test.go"
-	contents := fileGetContents(question.getFilePath(question.TitleSnake() + testExt))
-	if bytes.Count(contents, []byte("\n")) <= 2 {
-		// match function name
-		reg := regexp.MustCompile(`func (\w+?)\(`)
-		matches := reg.FindStringSubmatch(code.Code)
-		funcName := "Func"
-		if len(matches) >= 2 {
-			funcName = matches[1]
-		}
-		content = strings.NewReplacer(
-			"{{packageName}}", question.PackageName(),
-			"{{funcName}}", strings.Title(funcName),
-		).Replace(testTpl)
-		question.saveCodeContent(content, testExt)
-	}
-}
-
-func handleCodeBash(question *questionType, code codeSnippetsType) {
-	question.saveCodeContent("#!/usr/bin/env bash\n\n"+code.Code, ".bash", true)
-}
-
-func handleCodePython(question *questionType, code codeSnippetsType) {
-	question.saveCodeContent("#!/usr/bin/env python\n\n"+code.Code, ".py", true)
-}
-
-func handleCodeSQL(question *questionType, code codeSnippetsType) {
-	question.saveCodeContent(code.Code, ".sql")
-	question.saveMysqlSchemas()
-}
-
-func filterContents(cts string) string {
-	cts = strings.ReplaceAll(cts, "\r", "")
-	cts = strings.ReplaceAll(cts, `src="/static`, `src="https://assets.leetcode.com/static_assets/public`)
-	return cts
-}
-
-func getContent(filename string) string {
-	var qd QuestionDataType
-	cts := fileGetContents(filename)
-	jsonDecode(cts, &qd)
-	return qd.Data.Question.Content
-}
diff --git a/internal/leetcode/question_translation.go b/internal/leetcode/question_translation.go
deleted file mode 100644
index b403de568..000000000
--- a/internal/leetcode/question_translation.go
+++ /dev/null
@@ -1,50 +0,0 @@
-package leetcode
-
-import (
-	"log"
-	"os"
-	"strconv"
-)
-
-// QuestionTranslationType - leetcode.QuestionTranslationType
-type QuestionTranslationType struct {
-	Errors []errorType `json:"errors"`
-	Data   qtDataType  `json:"data"`
-}
-
-type qtDataType struct {
-	Translations []translationsType `json:"translations"`
-}
-
-type translationsType struct {
-	Title      string `json:"title"`
-	QuestionID string `json:"questionId"`
-	TypeName   string `json:"__typename"`
-}
-
-// GetQuestionTranslation - leetcode.GetQuestionTranslation
-func GetQuestionTranslation() (qt QuestionTranslationType) {
-	jsonStr := `{
-		"operationName": "getQuestionTranslation",
-		"variables": {},
-		"query": "query getQuestionTranslation($lang: String) {\n  translations: allAppliedQuestionTranslations(lang: $lang) {\n    title\n    questionId\n    __typename\n  }\n}\n"
-	}`
-	graphQLRequest(graphQLCnURL, jsonStr, questionTranslationFile, 2, &qt)
-	if qt.Data.Translations == nil {
-		_ = os.Remove(getCachePath(questionTranslationFile))
-		for _, err := range qt.Errors {
-			log.Println(err.Message)
-		}
-	}
-	return
-}
-
-func init() {
-	translation := GetQuestionTranslation()
-	for _, item := range translation.Data.Translations {
-		id := item.QuestionID
-		if id, err := strconv.Atoi(id); err == nil {
-			translationSet[id] = item.Title
-		}
-	}
-}
diff --git a/internal/leetcode/topic_tag.go b/internal/leetcode/topic_tag.go
deleted file mode 100644
index d045f1a28..000000000
--- a/internal/leetcode/topic_tag.go
+++ /dev/null
@@ -1,178 +0,0 @@
-package leetcode
-
-import (
-	"bytes"
-	"fmt"
-	"log"
-	"os"
-	"path/filepath"
-	"regexp"
-	"sort"
-	"strconv"
-	"sync"
-
-	"github.com/awesee/leetcode/internal/client"
-)
-
-var (
-	mu       sync.Mutex
-	initTags []TagType
-	tagsFile = filepath.Join("tag", "tags.json")
-)
-
-// TagType - leetcode.TagType
-type TagType struct {
-	Name           string
-	Slug           string
-	TranslatedName string
-}
-
-// SaveContents - leetcode.SaveContents
-func (tag *TagType) SaveContents() {
-	questions := GetTopicTag(tag.Slug).Data.TopicTag.Questions
-	sort.Slice(questions, func(i, j int) bool {
-		return questions[i].frontendID() > questions[j].frontendID()
-	})
-	var buf bytes.Buffer
-	buf.WriteString(authInfo("tag"))
-	buf.WriteString(fmt.Sprintf("\n## [话题分类](../README.md) > %s\n\n", tag.name()))
-	buf.WriteString("| # | 题目 | 标签 | 难度 |\n")
-	buf.WriteString("| :-: | - | - | :-: |\n")
-	format := "| %d | [%s](../../problems/%s)%s | %s | %s |\n"
-	preID := 0
-	for _, question := range questions {
-		if question.TranslatedTitle == "" {
-			question.TranslatedTitle = question.Title
-		}
-		if question.frontendID() > 0 && question.frontendID() != preID {
-			preID = question.frontendID()
-			buf.WriteString(fmt.Sprintf(format, question.frontendID(), question.TranslatedTitle, question.TitleSlug, question.IsPaidOnly.Str(), question.TagsStr(), question.Difficulty))
-		}
-	}
-	filename := filepath.Join("tag", tag.Slug, "README.md")
-	filePutContents(filename, buf.Bytes())
-}
-
-func (tag *TagType) name() string {
-	if tag.TranslatedName != "" {
-		return tag.TranslatedName
-	}
-	return tag.Name
-}
-
-// TopicTagType - leetcode.TopicTagType
-type TopicTagType struct {
-	Errors []errorType `json:"errors"`
-	Data   ttDataType  `json:"data"`
-}
-
-type ttDataType struct {
-	TopicTag ttType `json:"topicTag"`
-}
-
-type ttType struct {
-	Name           string           `json:"name"`
-	TranslatedName string           `json:"translatedName"`
-	Questions      []ttQuestionType `json:"questions"`
-}
-
-type ttQuestionType struct {
-	QuestionID         string    `json:"questionId"`
-	QuestionFrontendID string    `json:"questionFrontendId"`
-	Title              string    `json:"title"`
-	TitleSlug          string    `json:"titleSlug"`
-	TranslatedTitle    string    `json:"translatedTitle"`
-	TranslatedContent  string    `json:"translatedContent"`
-	IsPaidOnly         paidType  `json:"isPaidOnly"`
-	Difficulty         string    `json:"difficulty"`
-	TopicTags          []TagType `json:"topicTags"`
-}
-
-func (question *ttQuestionType) TagsStr() string {
-	var buf bytes.Buffer
-	format := "[[%s](../%s/README.md)] "
-	for _, tag := range question.TopicTags {
-		buf.WriteString(fmt.Sprintf(format, tag.name(), tag.Slug))
-	}
-	saveTags(question.TopicTags)
-	return buf.String()
-}
-
-func (question *ttQuestionType) frontendID() int {
-	id := titleSlugID[question.TitleSlug]
-	if id != 0 {
-		return id
-	}
-	id, _ = strconv.Atoi(question.QuestionFrontendID)
-	return id
-}
-
-// GetTags - leetcode.GetTags
-func GetTags() (tags []TagType) {
-	cts := fileGetContents(tagsFile)
-	jsonDecode(cts, &tags)
-	tags = tagsUnique(tags)
-	return
-}
-
-// GetTopicTag - leetcode.GetTopicTag
-func GetTopicTag(slug string) (tt TopicTagType) {
-	jsonStr := `{
-		"operationName": "getTopicTag",
-		"variables": {
-			"slug": "` + slug + `"
-		},
-		"query": "query getTopicTag($slug: String!) {\n  topicTag(slug: $slug) {\n    name\n    translatedName\n    questions {\n      status\n      questionId\n      questionFrontendId\n      title\n      titleSlug\n      translatedTitle\n      stats\n      difficulty\n      isPaidOnly\n      topicTags {\n        name\n        translatedName\n        slug\n        __typename\n      }\n      __typename\n    }\n    frequencies\n    __typename\n  }\n  favoritesLists {\n    publicFavorites {\n      ...favoriteFields\n      __typename\n    }\n    privateFavorites {\n      ...favoriteFields\n      __typename\n    }\n    __typename\n  }\n}\n\nfragment favoriteFields on FavoriteNode {\n  idHash\n  id\n  name\n  isPublicFavorite\n  viewCount\n  creator\n  isWatched\n  questions {\n    questionId\n    title\n    titleSlug\n    __typename\n  }\n  __typename\n}\n"
-	}`
-	filename := fmt.Sprintf(topicTagFile, slugToSnake(slug))
-	graphQLRequest(graphQLCnURL, jsonStr, filename, 2, &tt)
-	if tt.Data.TopicTag.Name == "" {
-		_ = os.Remove(getCachePath(filename))
-		for _, err := range tt.Errors {
-			log.Println(slug, err.Message)
-		}
-	}
-	return
-}
-
-func saveTags(tags []TagType) {
-	mu.Lock()
-	defer mu.Unlock()
-	tags = append(GetTags(), tags...)
-	filePutContents(tagsFile, jsonEncode(tagsUnique(tags)))
-}
-
-func tagsUnique(tags []TagType) []TagType {
-	rs, top := make([]TagType, 0, len(tags)), 1
-	tags = append(initTags, tags...)
-	var flag = make(map[string]int)
-	for _, tag := range tags {
-		i := flag[tag.Slug]
-		if i == 0 {
-			rs = append(rs, tag)
-			flag[tag.Slug] = top
-			top++
-		} else {
-			if tag.Name != "" {
-				rs[i-1].Name = tag.Name
-				rs[i-1].TranslatedName = tag.Name
-			}
-			if tag.TranslatedName != "" {
-				rs[i-1].TranslatedName = tag.TranslatedName
-			}
-		}
-	}
-	return rs
-}
-
-func init() {
-	html := remember(problemsetAllFile, 3, func() []byte {
-		return client.Get(problemsetAllURL)
-	})
-	reg := regexp.MustCompile(`href="/tag/(\S+?)/"`)
-	for _, matches := range reg.FindAllStringSubmatch(string(html), -1) {
-		if len(matches) >= 2 {
-			initTags = append(initTags, TagType{Slug: matches[1]})
-		}
-	}
-}
diff --git a/internal/open/open.go b/internal/open/open.go
deleted file mode 100644
index 3e6bf14be..000000000
--- a/internal/open/open.go
+++ /dev/null
@@ -1,39 +0,0 @@
-// Package open implements the command open.
-package open
-
-import (
-	"fmt"
-	"strconv"
-
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/browser"
-	"github.com/awesee/leetcode/internal/leetcode"
-)
-
-// CmdOpen - open.CmdOpen
-var CmdOpen = &base.Command{
-	Run:       runOpen,
-	UsageLine: "open <QuestionId>",
-	Short:     "open a problem solution in browser",
-	Long:      "open a problem solution in browser.",
-}
-
-func runOpen(cmd *base.Command, args []string) {
-	if len(args) != 1 {
-		cmd.Usage()
-		return
-	}
-	id, err := strconv.Atoi(args[0])
-	if err != nil {
-		cmd.Usage()
-		return
-	}
-	problems := leetcode.ProblemsAll()
-	for _, problem := range problems.StatStatusPairs {
-		if problem.Stat.FrontendQuestionID == id {
-			titleSlug := problem.Stat.QuestionTitleSlug
-			browser.Open(fmt.Sprintf("%s/problems/%s", base.URL, titleSlug))
-			break
-		}
-	}
-}
diff --git a/internal/page/page.go b/internal/page/page.go
deleted file mode 100644
index a58df6130..000000000
--- a/internal/page/page.go
+++ /dev/null
@@ -1,24 +0,0 @@
-// Package page implements the command page.
-package page
-
-import (
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/readme"
-)
-
-// CmdPage - page.CmdPage
-var CmdPage = &base.Command{
-	Run:       runPage,
-	UsageLine: "page",
-	Short:     "build index.md file",
-	Long:      "build page file(index.md).",
-	Hidden:    true,
-}
-
-func runPage(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		cmd.Usage()
-		return
-	}
-	readme.CmdReadme.Run(readme.CmdReadme, []string{"page"})
-}
diff --git a/internal/post/post.go b/internal/post/post.go
deleted file mode 100644
index 9238b6ff7..000000000
--- a/internal/post/post.go
+++ /dev/null
@@ -1,132 +0,0 @@
-// Package post implements the command post.
-package post
-
-import (
-	"bytes"
-	"fmt"
-	"os"
-	"path/filepath"
-	"regexp"
-	"strings"
-	"time"
-
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/leetcode"
-)
-
-const frontMatter = `---
-layout:     single
-title:      "%s"
-date:       %s +0800
-categories: [Leetcode]
-tags:       [%s]
-permalink:  /problems/%s/
----
-`
-
-const tagTmpl = `---
-title: "%s"
-layout: tag
-permalink: /tags/%s/
-taxonomy: %s
----
-`
-
-// CmdPost - post.CmdPost
-var CmdPost = &base.Command{
-	Run:       runPost,
-	UsageLine: "post",
-	Short:     "build post files",
-	Long:      "build all post files.",
-	Hidden:    true,
-}
-
-var (
-	homeDir, _ = os.UserHomeDir()
-	basePath   = filepath.Join(homeDir, "awesee", "awesee")
-)
-
-func runPost(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		cmd.Usage()
-		return
-	}
-	formatFilename := "%s-%s.md"
-	formatTopicTag := "  [[%s](%s/tag/%s/README.md)]\n"
-	formatSimilarQuestion := "  1. [%s](/problems/%s)%s\n"
-	problems := leetcode.ProblemsAll()
-	for _, problem := range problems.StatStatusPairs {
-		id := problem.Stat.FrontendQuestionID
-		titleSlug := problem.Stat.QuestionTitleSlug
-		question := leetcode.QuestionData(titleSlug, false).Data.Question
-		if question.TranslatedContent != "" {
-			fmt.Println(id, "\t"+question.TranslatedTitle)
-			var buf bytes.Buffer
-			t := time.Date(2016, 1, 1, 21, 30, 0, 0, time.Local)
-			t = t.AddDate(0, 0, id)
-			var tags []string
-			var tagsBuf bytes.Buffer
-			for _, tag := range question.TopicTags {
-				tags = append(tags, tag.Name)
-				if tag.TranslatedName != "" {
-					tag.Name = tag.TranslatedName
-				}
-				tagsBuf.WriteString(fmt.Sprintf(formatTopicTag, tag.Name, base.URL, tag.Slug))
-			}
-			buf.WriteString(fmt.Sprintf(frontMatter,
-				question.TranslatedTitle,
-				t.Format("2006-01-02 15:04:05"),
-				strings.Join(tags, ", "),
-				question.TitleSlug,
-			))
-			buf.WriteString(fmt.Sprintf("\n## %d. %s%s\n\n", question.FrontendID(), question.TranslatedTitle, question.Difficulty.Str()))
-			buf.WriteString("{% raw %}\n\n")
-			content := strings.ReplaceAll(question.TranslatedContent, "\r", "")
-			// remove style
-			reg := regexp.MustCompile(`<style[\S\s]+?</style>`)
-			content = reg.ReplaceAllString(content, "")
-			content = strings.ReplaceAll(content, "\n\n\t", "\n\t")
-			content = strings.TrimSpace(content)
-			buf.WriteString(content)
-			buf.WriteString("\n\n{% endraw %}\n")
-			if len(question.TopicTags) > 0 {
-				buf.WriteString("\n### 相关话题\n")
-			}
-			buf.Write(tagsBuf.Bytes())
-			sq := question.GetSimilarQuestion()
-			if len(sq) > 0 {
-				buf.WriteString("\n### 相似题目\n")
-			}
-			for _, q := range sq {
-				if q.TranslatedTitle != "" {
-					q.Title = q.TranslatedTitle
-				}
-				buf.WriteString(fmt.Sprintf(formatSimilarQuestion, q.Title, q.TitleSlug, q.Difficulty.Str()))
-			}
-			buf.WriteString("\n---\n")
-			buf.WriteString(fmt.Sprintf("\n## [解法](%s/problems/%s)\n", base.URL, question.TitleSlug))
-			filename := fmt.Sprintf(formatFilename, t.Format("2006-01-02"), question.TitleSlug)
-			oldPath := filepath.Join(basePath, "leetcode", filename)
-			newPath := filepath.Join(basePath, "_posts", filename)
-			base.FilePutContents(oldPath, buf.Bytes())
-			if leetcode.IsSolved(id) {
-				_ = os.Rename(oldPath, newPath)
-			} else {
-				_ = os.Remove(newPath)
-			}
-		}
-	}
-	postTags()
-}
-
-func postTags() {
-	for _, tag := range leetcode.GetTags() {
-		title := tag.TranslatedName
-		if title == "" {
-			title = tag.Name
-		}
-		filename := fmt.Sprintf("tag-%s.md", tag.Slug)
-		data := []byte(fmt.Sprintf(tagTmpl, title, tag.Slug, tag.Name))
-		base.FilePutContents(filepath.Join(basePath, "_pages", filename), data)
-	}
-}
diff --git a/internal/question/question.go b/internal/question/question.go
deleted file mode 100644
index 3dd7e56eb..000000000
--- a/internal/question/question.go
+++ /dev/null
@@ -1,43 +0,0 @@
-// Package question implements the command question.
-package question
-
-import (
-	"fmt"
-	"strconv"
-
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/leetcode"
-)
-
-// CmdQuestion - question.CmdQuestion
-var CmdQuestion = &base.Command{
-	Run:       runQuestion,
-	UsageLine: "question <QuestionId>",
-	Short:     "build problem solution file",
-	Long:      "build problem's description,solution file.",
-}
-
-func runQuestion(cmd *base.Command, args []string) {
-	if len(args) != 1 {
-		cmd.Usage()
-		return
-	}
-	id, err := strconv.Atoi(args[0])
-	if err != nil {
-		return
-	}
-	problems := leetcode.ProblemsAll()
-	for _, problem := range problems.StatStatusPairs {
-		if problem.Stat.FrontendQuestionID == id {
-			fmt.Println(id, "\t"+problem.Stat.QuestionTitle)
-			titleSlug := problem.Stat.QuestionTitleSlug
-			question := leetcode.QuestionData(titleSlug, true).Data.Question
-			if question.Content == "" && problem.PaidOnly == true && problem.Stat.QuestionArticleLive {
-				question.Content = leetcode.GetDescription(problem.Stat.QuestionArticleSlug)
-			}
-			question.SaveContent()
-			question.SaveCodeSnippet()
-			return
-		}
-	}
-}
diff --git a/internal/readme/readme.go b/internal/readme/readme.go
deleted file mode 100644
index 0a4e1e10f..000000000
--- a/internal/readme/readme.go
+++ /dev/null
@@ -1,106 +0,0 @@
-// Package readme implements the command readme.
-package readme
-
-import (
-	"bytes"
-	"fmt"
-	"path/filepath"
-
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/leetcode"
-)
-
-const defaultStr = `
-# [LeetCode](https://awesee.github.io/leetcode)
-LeetCode Problems' Solutions
-[[力扣](https://awesee.github.io/categories/leetcode/) ∙ [话题分类](https://github.com/awesee/leetcode/blob/master/tag/README.md)]
-
-[![Go](https://github.com/awesee/leetcode/workflows/Go/badge.svg)](https://github.com/awesee/leetcode/actions)
-[![codecov](https://codecov.io/gh/awesee/leetcode/branch/master/graph/badge.svg)](https://codecov.io/gh/awesee/leetcode)
-[![Go Report Card](https://goreportcard.com/badge/github.com/awesee/leetcode)](https://goreportcard.com/report/github.com/awesee/leetcode)
-[![GitHub contributors](https://img.shields.io/github/contributors/awesee/leetcode.svg)](https://github.com/awesee/leetcode/graphs/contributors)
-[![license](https://img.shields.io/github/license/awesee/leetcode.svg)](https://github.com/awesee/leetcode/blob/master/LICENSE)
-[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fawesee%2Fleetcode.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fawesee%2Fleetcode?ref=badge_shield)
-[![Join the chat](https://badges.gitter.im/awesee/leetcode.svg)](https://gitter.im/awesee/leetcode?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-
-`
-
-// CmdReadme - readme.CmdReadme
-var CmdReadme = &base.Command{
-	Run:       runReadme,
-	UsageLine: "readme",
-	Short:     "build README.md file",
-	Long:      "build README.md file.",
-	Hidden:    true,
-}
-
-var (
-	buildCmd = "readme"
-	fileName = "README.md"
-	maxID    = 0
-	pageSize = 300
-	step     = 50
-	num      = 6
-)
-
-func runReadme(cmd *base.Command, args []string) {
-	if len(args) == 1 && args[0] == "page" {
-		buildCmd = "page"
-		fileName = "index.md"
-		leetcode.LockStr = " &hearts;"
-	}
-	if len(args) > 1 {
-		cmd.Usage()
-		return
-	}
-	var buf bytes.Buffer
-	buf.WriteString(base.AuthInfo(buildCmd))
-	buf.WriteString(defaultStr)
-	writeProblems(&buf)
-	base.FilePutContents(fileName, buf.Bytes())
-}
-
-func writeProblems(buf *bytes.Buffer) {
-	problems := leetcode.ProblemsAll().StatStatusPairs
-	count := len(problems)
-	if count > 0 {
-		maxID = problems[0].Stat.FrontendQuestionID
-		writeNav(buf)
-		// list
-		buf.WriteString("| # | Title | Solution | Difficulty |\n")
-		buf.WriteString("| :-: | - | - | :-: |\n")
-		n := buf.Len()
-		for i := 1; i < maxID/pageSize; i++ {
-			for problems[count-1].Stat.FrontendQuestionID <= pageSize*i {
-				count--
-				problems[count].WriteRow(buf, "../problems")
-			}
-			fileName := filepath.Join("readme", fmt.Sprintf("%d-%d.md", pageSize*(i-1)+1, pageSize*i))
-			base.FilePutContents(fileName, buf.Bytes())
-			buf.Truncate(n)
-		}
-		for _, problem := range problems[0:count] {
-			problem.WriteRow(buf, "problems")
-		}
-	}
-}
-
-func writeNav(buf *bytes.Buffer) {
-	// table
-	buf.WriteString("<table><thead>\n")
-	for i := 0; i < maxID; i += step * num {
-		buf.WriteString("<tr>\n")
-		for j := 0; j < num; j++ {
-			buf.WriteString(fmt.Sprintf("\t<th align=\"center\"><a href=\"%s\">[%d-%d]</a></th>\n", linkStr(i+j*step+step), 1+i+j*step, i+j*step+step))
-		}
-		buf.WriteString("</tr>\n")
-	}
-	buf.WriteString("</thead></table>\n\n")
-}
-
-func linkStr(num int) string {
-	if num > maxID-maxID%pageSize-pageSize {
-		return fmt.Sprintf("%s/README.md#%d", base.URL, num)
-	}
-	return fmt.Sprintf("%s/readme/%d-%d.md#%d", base.URL, (num-1)/pageSize*pageSize+1, ((num-1)/pageSize+1)*pageSize, num-step+1)
-}
diff --git a/internal/tag/tag.go b/internal/tag/tag.go
deleted file mode 100644
index 02819523a..000000000
--- a/internal/tag/tag.go
+++ /dev/null
@@ -1,59 +0,0 @@
-// Package tag implements the command tag.
-package tag
-
-import (
-	"bytes"
-	"fmt"
-	"reflect"
-	"sync"
-
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/leetcode"
-)
-
-// CmdTag - tag.CmdTag
-var CmdTag = &base.Command{
-	Run:       runTag,
-	UsageLine: "tag",
-	Short:     "build all tags file",
-	Long:      "build all tags README.md file.",
-	Hidden:    true,
-}
-
-func runTag(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		cmd.Usage()
-		return
-	}
-	var wg sync.WaitGroup
-	var buf bytes.Buffer
-	buf.WriteString(base.AuthInfo("tag"))
-	buf.WriteString("\n## 话题分类\n\n")
-	buf.WriteString("| # | Topic | 话题 | | # | Topic | 话题 |\n")
-	buf.WriteString("| :-: | - | :-: | - | :-: | - | :-: |\n")
-	format := "| %d | [%s](%s/README.md) | [%s](https://awesee.github.io/tags/%s/) | "
-	n := buf.Len()
-	for times := 0; times < 2; times++ {
-		buf.Truncate(n)
-		tags := leetcode.GetTags()
-		for i, tag := range tags {
-			if tag.Name != "" {
-				fmt.Println(i+1, "\t"+tag.Name)
-			}
-			buf.WriteString(fmt.Sprintf(format, i+1, tag.Name, tag.Slug, tag.TranslatedName, tag.Slug))
-			if i&1 == 1 {
-				buf.WriteString("\n")
-			}
-			wg.Add(1)
-			go func(tag leetcode.TagType) {
-				tag.SaveContents()
-				wg.Done()
-			}(tag)
-		}
-		if reflect.DeepEqual(tags, leetcode.GetTags()) {
-			break
-		}
-	}
-	base.FilePutContents("tag/README.md", buf.Bytes())
-	wg.Wait()
-}
diff --git a/internal/test/test.go b/internal/test/test.go
deleted file mode 100644
index 1ce2e7bf0..000000000
--- a/internal/test/test.go
+++ /dev/null
@@ -1,45 +0,0 @@
-// Package test implements the command test.
-package test
-
-import (
-	"os"
-	"os/exec"
-	"strconv"
-
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/leetcode"
-)
-
-// CmdTest - test.CmdTest
-var CmdTest = &base.Command{
-	Run:       runTest,
-	UsageLine: "test [QuestionId]",
-	Short:     "run go test",
-	Long:      "automates testing the packages.",
-}
-
-func runTest(cmd *base.Command, args []string) {
-	if len(args) > 1 {
-		cmd.Usage()
-		return
-	}
-	if _, err := os.Stat("problems"); err == nil {
-		target := "./..."
-		if len(args) == 1 {
-			if id, err := strconv.Atoi(args[0]); err == nil {
-				problems := leetcode.ProblemsAll()
-				for _, problem := range problems.StatStatusPairs {
-					if problem.Stat.FrontendQuestionID == id {
-						target = "./problems/" + problem.Stat.QuestionTitleSlug
-						break
-					}
-				}
-			}
-		}
-		c := exec.Command("go", "test", target)
-		c.Stdout = os.Stdout
-		c.Stderr = os.Stderr
-		err := c.Run()
-		base.CheckErr(err)
-	}
-}
diff --git a/internal/update/update.go b/internal/update/update.go
deleted file mode 100644
index 47a9ebca3..000000000
--- a/internal/update/update.go
+++ /dev/null
@@ -1,32 +0,0 @@
-// Package update implements the command update.
-package update
-
-import (
-	"fmt"
-	"os"
-	"os/exec"
-
-	"github.com/awesee/leetcode/internal/base"
-)
-
-// CmdUpdate - update.CmdUpdate
-var CmdUpdate = &base.Command{
-	Run:       runUpdate,
-	UsageLine: "update",
-	Short:     "update or upgrade self",
-	Long:      fmt.Sprintf("fetch the newest version of %s.", base.CmdName),
-}
-
-func runUpdate(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		cmd.Usage()
-		return
-	}
-	err := exec.Command("go", "get", "-u", "github.com/awesee/leetcode").Run()
-	base.CheckErr(err)
-	c := exec.Command(base.CmdName, "version")
-	c.Stdout = os.Stdout
-	c.Stderr = os.Stderr
-	err = c.Run()
-	base.CheckErr(err)
-}
diff --git a/internal/version/version.go b/internal/version/version.go
deleted file mode 100644
index 87f26aefc..000000000
--- a/internal/version/version.go
+++ /dev/null
@@ -1,32 +0,0 @@
-// Package version implements the command version.
-package version
-
-import (
-	"fmt"
-	"runtime"
-
-	"github.com/awesee/leetcode/internal/base"
-)
-
-const version = "1.6.6"
-
-// CmdVersion - version.CmdVersion
-var CmdVersion = &base.Command{
-	Run:       runVersion,
-	UsageLine: "version",
-	Short:     fmt.Sprintf("print %s version", base.CmdName),
-	Long:      fmt.Sprintf("prints the %s version.", base.CmdName),
-}
-
-func runVersion(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		cmd.Usage()
-		return
-	}
-	fmt.Printf("%s version %s %s/%s\n", base.CmdName, version, runtime.GOOS, runtime.GOARCH)
-}
-
-// String - version.String
-func String() string {
-	return version
-}
diff --git a/main.go b/main.go
deleted file mode 100644
index 954f38eaf..000000000
--- a/main.go
+++ /dev/null
@@ -1,40 +0,0 @@
-// leetcode is a tool for managing leetcode source code.
-package main
-
-import (
-	"github.com/awesee/leetcode/internal/base"
-	"github.com/awesee/leetcode/internal/build"
-	"github.com/awesee/leetcode/internal/clean"
-	"github.com/awesee/leetcode/internal/description"
-	"github.com/awesee/leetcode/internal/help"
-	"github.com/awesee/leetcode/internal/helper"
-	"github.com/awesee/leetcode/internal/open"
-	"github.com/awesee/leetcode/internal/page"
-	"github.com/awesee/leetcode/internal/post"
-	"github.com/awesee/leetcode/internal/question"
-	"github.com/awesee/leetcode/internal/readme"
-	"github.com/awesee/leetcode/internal/tag"
-	"github.com/awesee/leetcode/internal/test"
-	"github.com/awesee/leetcode/internal/update"
-	"github.com/awesee/leetcode/internal/version"
-)
-
-func main() {
-	base.Register(
-		readme.CmdReadme,
-		page.CmdPage,
-		tag.CmdTag,
-		helper.CmdHelper,
-		question.CmdQuestion,
-		open.CmdOpen,
-		test.CmdTest,
-		description.CmdDescription,
-		update.CmdUpdate,
-		build.CmdBuild,
-		clean.CmdClean,
-		version.CmdVersion,
-		help.CmdHelp,
-		post.CmdPost,
-	)
-	base.Run()
-}
diff --git a/problems/01-matrix/01_matrix.go b/problems/01-matrix/01_matrix.go
deleted file mode 100644
index 0072d2b91..000000000
--- a/problems/01-matrix/01_matrix.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem542
-
-func updateMatrix(matrix [][]int) [][]int {
-	m, n := len(matrix), len(matrix[0])
-	MIN := m * n
-	// 根据 左方 和 上方 的格子，更新 (i,j)
-	for i := 0; i < m; i++ {
-		for j := 0; j < n; j++ {
-			if matrix[i][j] == 0 {
-				continue
-			}
-			matrix[i][j] = MIN
-			if 0 <= i-1 {
-				matrix[i][j] = min(matrix[i][j], matrix[i-1][j]+1)
-			}
-			if 0 <= j-1 {
-				matrix[i][j] = min(matrix[i][j], matrix[i][j-1]+1)
-			}
-		}
-	}
-	// 根据 右方 和 下方 的格子，更新 (i,j)
-	for i := m - 1; 0 <= i; i-- {
-		for j := n - 1; 0 <= j; j-- {
-			if matrix[i][j] == 0 {
-				continue
-			}
-			if i+1 < m {
-				matrix[i][j] = min(matrix[i][j], matrix[i+1][j]+1)
-			}
-			if j+1 < n {
-				matrix[i][j] = min(matrix[i][j], matrix[i][j+1]+1)
-			}
-		}
-	}
-	return matrix
-}
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
diff --git a/problems/01-matrix/01_matrix_test.go b/problems/01-matrix/01_matrix_test.go
deleted file mode 100644
index c7178e416..000000000
--- a/problems/01-matrix/01_matrix_test.go
+++ /dev/null
@@ -1,46 +0,0 @@
-package problem542
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   [][]int
-	want [][]int
-}
-
-func TestUpdateMatrix(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{0, 0, 0},
-				{0, 1, 0},
-				{0, 0, 0},
-			},
-			want: [][]int{
-				{0, 0, 0},
-				{0, 1, 0},
-				{0, 0, 0},
-			},
-		},
-		{
-			in: [][]int{
-				{0, 0, 0},
-				{0, 1, 0},
-				{1, 1, 1},
-			},
-			want: [][]int{
-				{0, 0, 0},
-				{0, 1, 0},
-				{1, 2, 1},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := updateMatrix(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/01-matrix/README.md b/problems/01-matrix/README.md
deleted file mode 100644
index 47aff04e7..000000000
--- a/problems/01-matrix/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-string-ii "Reverse String II")
-　　　　　　　　　　　　　　　　
-[Next >](../diameter-of-binary-tree "Diameter of Binary Tree")
-
-## [542. 01 Matrix (Medium)](https://leetcode.com/problems/01-matrix "01 矩阵")
-
-<p>Given an <code>m x n</code> binary matrix <code>mat</code>, return <em>the distance of the nearest </em><code>0</code><em> for each cell</em>.</p>
-
-<p>The distance between two adjacent cells is <code>1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/01-1-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> mat = [[0,0,0],[0,1,0],[0,0,0]]
-<strong>Output:</strong> [[0,0,0],[0,1,0],[0,0,0]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/01-2-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> mat = [[0,0,0],[0,1,0],[1,1,1]]
-<strong>Output:</strong> [[0,0,0],[0,1,0],[1,2,1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= m * n &lt;= 10<sup>4</sup></code></li>
-	<li><code>mat[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-	<li>There is at least one <code>0</code> in <code>mat</code>.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/1-bit-and-2-bit-characters/1_bit_and_2_bit_characters.go b/problems/1-bit-and-2-bit-characters/1_bit_and_2_bit_characters.go
deleted file mode 100644
index 4246a27ae..000000000
--- a/problems/1-bit-and-2-bit-characters/1_bit_and_2_bit_characters.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package problem717
-
-func isOneBitCharacter(bits []int) bool {
-	i, l := 0, len(bits)-1
-	for i < l {
-		i += bits[i] + 1
-	}
-	return i == l
-}
diff --git a/problems/1-bit-and-2-bit-characters/1_bit_and_2_bit_characters_test.go b/problems/1-bit-and-2-bit-characters/1_bit_and_2_bit_characters_test.go
deleted file mode 100644
index f70c45639..000000000
--- a/problems/1-bit-and-2-bit-characters/1_bit_and_2_bit_characters_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem717
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestIsOneBitCharacter(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 0, 0},
-			want: true,
-		},
-		{
-			in:   []int{1, 1, 1, 0},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isOneBitCharacter(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/1-bit-and-2-bit-characters/README.md b/problems/1-bit-and-2-bit-characters/README.md
deleted file mode 100644
index 12f6933a1..000000000
--- a/problems/1-bit-and-2-bit-characters/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-stack "Max Stack")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-length-of-repeated-subarray "Maximum Length of Repeated Subarray")
-
-## [717. 1-bit and 2-bit Characters (Easy)](https://leetcode.com/problems/1-bit-and-2-bit-characters "1比特与2比特字符")
-
-<p>We have two special characters:</p>
-
-<ul>
-	<li>The first character can be represented by one bit <code>0</code>.</li>
-	<li>The second character can be represented by two bits (<code>10</code> or <code>11</code>).</li>
-</ul>
-
-<p>Given a binary array <code>bits</code> that ends with <code>0</code>, return <code>true</code> if the last character must be a one-bit character.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> bits = [1,0,0]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The only way to decode it is two-bit character and one-bit character.
-So the last character is one-bit character.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> bits = [1,1,1,0]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The only way to decode it is two-bit character and two-bit character.
-So the last character is not one-bit character.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= bits.length &lt;= 1000</code></li>
-	<li><code>bits[i]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Gray Code](../gray-code) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep track of where the next character starts.  At the end, you want to know if you started on the last bit.
-</details>
diff --git a/problems/132-pattern/132_pattern.go b/problems/132-pattern/132_pattern.go
deleted file mode 100644
index 021713a47..000000000
--- a/problems/132-pattern/132_pattern.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem456
-
-func find132pattern(nums []int) bool {
-	ak, ajStack := -1<<31, make([]int, 0, len(nums))
-	for i := len(nums) - 1; 0 <= i; i-- {
-		if nums[i] < ak {
-			return true
-		}
-		for len(ajStack) > 0 && ajStack[len(ajStack)-1] < nums[i] {
-			ak = ajStack[len(ajStack)-1]
-			ajStack = ajStack[:len(ajStack)-1]
-		}
-		ajStack = append(ajStack, nums[i])
-	}
-	return false
-}
diff --git a/problems/132-pattern/132_pattern_test.go b/problems/132-pattern/132_pattern_test.go
deleted file mode 100644
index eeaa7b8d7..000000000
--- a/problems/132-pattern/132_pattern_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem456
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestFind132pattern(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3, 4},
-			want: false,
-		},
-		{
-			in:   []int{3, 1, 4, 2},
-			want: true,
-		},
-		{
-			in:   []int{-1, 3, 2, 0},
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := find132pattern(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/132-pattern/README.md b/problems/132-pattern/README.md
deleted file mode 100644
index 3adc70a27..000000000
--- a/problems/132-pattern/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../assign-cookies "Assign Cookies")
-　　　　　　　　　　　　　　　　
-[Next >](../circular-array-loop "Circular Array Loop")
-
-## [456. 132 Pattern (Medium)](https://leetcode.com/problems/132-pattern "132 模式")
-
-<p>Given an array&nbsp;of <code>n</code> integers <code>nums</code>, a <strong>132 pattern</strong> is a subsequence of three integers <code>nums[i]</code>, <code>nums[j]</code> and <code>nums[k]</code> such that <code>i &lt; j &lt; k</code> and <code>nums[i] &lt; nums[k] &lt; nums[j]</code>.</p>
-
-<p>Return <em><code>true</code> if there is a <strong>132 pattern</strong> in <code>nums</code>, otherwise, return <code>false</code>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There is no 132 pattern in the sequence.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,4,2]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> There is a 132 pattern in the sequence: [1, 4, 2].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,3,2,0]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> There are three 132 patterns in the sequence: [-1, 3, 2], [-1, 3, 0] and [-1, 2, 0].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
diff --git a/problems/2-keys-keyboard/2_keys_keyboard.go b/problems/2-keys-keyboard/2_keys_keyboard.go
deleted file mode 100644
index a51bcd0e7..000000000
--- a/problems/2-keys-keyboard/2_keys_keyboard.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem650
-
-func minSteps(n int) int {
-	if n == 1 {
-		return 0
-	}
-	for i := 2; i < n; i++ {
-		if n%i == 0 {
-			return i + minSteps(n/i)
-		}
-	}
-	return n
-}
diff --git a/problems/2-keys-keyboard/2_keys_keyboard_test.go b/problems/2-keys-keyboard/2_keys_keyboard_test.go
deleted file mode 100644
index f5dc7cd19..000000000
--- a/problems/2-keys-keyboard/2_keys_keyboard_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem650
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestMinSteps(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   1,
-			want: 0,
-		},
-		{
-			in:   3,
-			want: 3,
-		},
-		{
-			in:   30,
-			want: 10,
-		},
-		{
-			in:   97,
-			want: 97,
-		},
-	}
-	for _, tt := range tests {
-		got := minSteps(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/2-keys-keyboard/README.md b/problems/2-keys-keyboard/README.md
deleted file mode 100644
index 6bf91790a..000000000
--- a/problems/2-keys-keyboard/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../dota2-senate "Dota2 Senate")
-　　　　　　　　　　　　　　　　
-[Next >](../4-keys-keyboard "4 Keys Keyboard")
-
-## [650. 2 Keys Keyboard (Medium)](https://leetcode.com/problems/2-keys-keyboard "只有两个键的键盘")
-
-<p>There is only one character <code>&#39;A&#39;</code> on the screen of a notepad. You can perform two operations on this notepad for each step:</p>
-
-<ul>
-	<li>Copy All: You can copy all the characters present on the screen (a partial copy is not allowed).</li>
-	<li>Paste: You can paste the characters which are copied last time.</li>
-</ul>
-
-<p>Given an integer <code>n</code>, return <em>the minimum number of operations to get the character</em> <code>&#39;A&#39;</code> <em>exactly</em> <code>n</code> <em>times on the screen</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Intitally, we have one character &#39;A&#39;.
-In step 1, we use Copy All operation.
-In step 2, we use Paste operation to get &#39;AA&#39;.
-In step 3, we use Paste operation to get &#39;AAA&#39;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [4 Keys Keyboard](../4-keys-keyboard) (Medium)
-  1. [Broken Calculator](../broken-calculator) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many characters may be there in the clipboard at the last step if n = 3? n = 7? n = 10? n = 24?
-</details>
diff --git a/problems/24-game/24_game.go b/problems/24-game/24_game.go
deleted file mode 100644
index 5a0d00173..000000000
--- a/problems/24-game/24_game.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem679
-
-import "sort"
-
-// 无法算出 24 的数字组合
-var bad = map[int]bool{
-	1111: true, 1112: true, 1113: true, 1114: true, 1115: true,
-	1116: true, 1117: true, 1119: true, 1122: true, 1123: true,
-	1124: true, 1125: true, 1133: true, 1159: true, 1167: true,
-	1177: true, 1178: true, 1179: true, 1189: true, 1199: true,
-	1222: true, 1223: true, 1299: true, 1355: true, 1499: true,
-	1557: true, 1558: true, 1577: true, 1667: true, 1677: true,
-	1678: true, 1777: true, 1778: true, 1899: true, 1999: true,
-	2222: true, 2226: true, 2279: true, 2299: true, 2334: true,
-	2555: true, 2556: true, 2599: true, 2677: true, 2777: true,
-	2779: true, 2799: true, 2999: true, 3358: true, 3467: true,
-	3488: true, 3555: true, 3577: true, 4459: true, 4466: true,
-	4467: true, 4499: true, 4779: true, 4999: true, 5557: true,
-	5558: true, 5569: true, 5579: true, 5777: true, 5778: true,
-	5799: true, 5899: true, 5999: true, 6667: true, 6677: true,
-	6678: true, 6699: true, 6777: true, 6778: true, 6779: true,
-	6788: true, 6999: true, 7777: true, 7778: true, 7779: true,
-	7788: true, 7789: true, 7799: true, 7888: true, 7899: true,
-	7999: true, 8888: true, 8889: true, 8899: true, 8999: true,
-	9999: true,
-}
-
-func judgePoint24(nums []int) bool {
-	sort.Ints(nums)
-	sum := 0
-	for i := 0; i < 4; i++ {
-		sum = sum*10 + nums[i]
-	}
-	return !bad[sum]
-}
diff --git a/problems/24-game/24_game_test.go b/problems/24-game/24_game_test.go
deleted file mode 100644
index d01352b98..000000000
--- a/problems/24-game/24_game_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem679
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestJudgePoint24(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{4, 1, 8, 7},
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 1, 2},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := judgePoint24(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/24-game/README.md b/problems/24-game/README.md
deleted file mode 100644
index 64205b65d..000000000
--- a/problems/24-game/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-parenthesis-string "Valid Parenthesis String")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-palindrome-ii "Valid Palindrome II")
-
-## [679. 24 Game (Hard)](https://leetcode.com/problems/24-game "24 点游戏")
-
-<p>You are given an integer array <code>cards</code> of length <code>4</code>. You have four cards, each containing a number in the range <code>[1, 9]</code>. You should arrange the numbers on these cards in a mathematical expression using the operators <code>[&#39;+&#39;, &#39;-&#39;, &#39;*&#39;, &#39;/&#39;]</code> and the parentheses <code>&#39;(&#39;</code> and <code>&#39;)&#39;</code> to get the value 24.</p>
-
-<p>You are restricted with the following rules:</p>
-
-<ul>
-	<li>The division operator <code>&#39;/&#39;</code> represents real division, not integer division.
-	<ul>
-		<li>For example, <code>4 / (1 - 2 / 3) = 4 / (1 / 3) = 12</code>.</li>
-	</ul>
-	</li>
-	<li>Every operation done is between two numbers. In particular, we cannot use <code>&#39;-&#39;</code> as a unary operator.
-	<ul>
-		<li>For example, if <code>cards = [1, 1, 1, 1]</code>, the expression <code>&quot;-1 - 1 - 1 - 1&quot;</code> is <strong>not allowed</strong>.</li>
-	</ul>
-	</li>
-	<li>You cannot concatenate numbers together
-	<ul>
-		<li>For example, if <code>cards = [1, 2, 1, 2]</code>, the expression <code>&quot;12 + 12&quot;</code> is not valid.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <code>true</code> if you can get such expression that evaluates to <code>24</code>, and <code>false</code> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> cards = [4,1,8,7]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> (8-4) * (7-1) = 24
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> cards = [1,2,1,2]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>cards.length == 4</code></li>
-	<li><code>1 &lt;= cards[i] &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
diff --git a/problems/3sum-closest/3sum_closest.go b/problems/3sum-closest/3sum_closest.go
deleted file mode 100644
index 1eb41e9f2..000000000
--- a/problems/3sum-closest/3sum_closest.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem16
-
-import (
-	"math"
-	"sort"
-)
-
-func threeSumClosest(nums []int, target int) int {
-	sort.Ints(nums)
-	ans, diff, n := math.MaxInt32, math.MaxInt32, len(nums)
-	for i := 0; i < n-2; i++ {
-		l, r := i+1, n-1
-		for l < r {
-			sum := nums[i] + nums[l] + nums[r]
-			if sum < target {
-				if target-sum < diff {
-					ans, diff = sum, target-sum
-				}
-				l++
-			} else if sum > target {
-				if sum-target < diff {
-					ans, diff = sum, sum-target
-				}
-				r--
-			} else {
-				return target
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/3sum-closest/3sum_closest_test.go b/problems/3sum-closest/3sum_closest_test.go
deleted file mode 100644
index 90cd6c8ec..000000000
--- a/problems/3sum-closest/3sum_closest_test.go
+++ /dev/null
@@ -1,45 +0,0 @@
-package problem16
-
-import "testing"
-
-type testType struct {
-	in     []int
-	target int
-	want   int
-}
-
-func TestThreeSumClosest(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:     []int{-1, 2, 1, -4},
-			target: 1,
-			want:   2,
-		},
-		{
-			in:     []int{-1, 0, 1, 2, -1, -4},
-			target: 1,
-			want:   1,
-		},
-		{
-			in:     []int{0, 0, 0, 0},
-			target: 1,
-			want:   0,
-		},
-		{
-			in:     []int{-2, 0, 0, 2, 2, 2},
-			target: 2,
-			want:   2,
-		},
-		{
-			in:     []int{-2, 0, 0, 2, 2, 2, 2},
-			target: 1,
-			want:   0,
-		},
-	}
-	for _, tt := range tests {
-		got := threeSumClosest(tt.in, tt.target)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/3sum-closest/README.md b/problems/3sum-closest/README.md
deleted file mode 100644
index b96e513a8..000000000
--- a/problems/3sum-closest/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../3sum "3Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../letter-combinations-of-a-phone-number "Letter Combinations of a Phone Number")
-
-## [16. 3Sum Closest (Medium)](https://leetcode.com/problems/3sum-closest "最接近的三数之和")
-
-<p>Given an integer array <code>nums</code> of length <code>n</code> and an integer <code>target</code>, find three integers in <code>nums</code> such that the sum is closest to <code>target</code>.</p>
-
-<p>Return <em>the sum of the three integers</em>.</p>
-
-<p>You may assume that each input would have exactly one solution.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,2,1,-4], target = 1
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,0], target = 1
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>-1000 &lt;= nums[i] &lt;= 1000</code></li>
-	<li><code>-10<sup>4</sup> &lt;= target &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [3Sum](../3sum) (Medium)
-  1. [3Sum Smaller](../3sum-smaller) (Medium)
diff --git a/problems/3sum-smaller/3sum_smaller.go b/problems/3sum-smaller/3sum_smaller.go
deleted file mode 100644
index 0f1bb3515..000000000
--- a/problems/3sum-smaller/3sum_smaller.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem259
diff --git a/problems/3sum-smaller/3sum_smaller_test.go b/problems/3sum-smaller/3sum_smaller_test.go
deleted file mode 100644
index 0f1bb3515..000000000
--- a/problems/3sum-smaller/3sum_smaller_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem259
diff --git a/problems/3sum-smaller/README.md b/problems/3sum-smaller/README.md
deleted file mode 100644
index bfa0d4d13..000000000
--- a/problems/3sum-smaller/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-digits "Add Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../single-number-iii "Single Number III")
-
-## [259. 3Sum Smaller (Medium)](https://leetcode.com/problems/3sum-smaller "较小的三数之和")
-
-<p>Given an array of <i>n</i> integers <i>nums</i> and a <i>target</i>, find the number of index triplets <code>i, j, k</code> with <code>0 &lt;= i &lt; j &lt; k &lt; n</code> that satisfy the condition <code>nums[i] + nums[j] + nums[k] &lt; target</code>.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> <i>nums</i> = <code>[-2,0,1,3]</code>, and <i>target</i> = 2
-<strong>Output:</strong> 2 
-<strong>Explanation:</strong>&nbsp;Because there are two triplets which sums are less than 2:
-&nbsp;            [-2,0,1]
-             [-2,0,3]
-</pre>
-
-<p><b style="font-family: sans-serif, Arial, Verdana, &quot;Trebuchet MS&quot;;">Follow up:</b> Could you solve it in <i>O</i>(<i>n</i><sup>2</sup>) runtime?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [3Sum](../3sum) (Medium)
-  1. [3Sum Closest](../3sum-closest) (Medium)
-  1. [Valid Triangle Number](../valid-triangle-number) (Medium)
-  1. [Two Sum Less Than K](../two-sum-less-than-k) (Easy)
diff --git a/problems/3sum-with-multiplicity/3sum_with_multiplicity.go b/problems/3sum-with-multiplicity/3sum_with_multiplicity.go
deleted file mode 100644
index 8fc63a912..000000000
--- a/problems/3sum-with-multiplicity/3sum_with_multiplicity.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem923
diff --git a/problems/3sum-with-multiplicity/3sum_with_multiplicity_test.go b/problems/3sum-with-multiplicity/3sum_with_multiplicity_test.go
deleted file mode 100644
index 8fc63a912..000000000
--- a/problems/3sum-with-multiplicity/3sum_with_multiplicity_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem923
diff --git a/problems/3sum-with-multiplicity/README.md b/problems/3sum-with-multiplicity/README.md
deleted file mode 100644
index d7bdf95a0..000000000
--- a/problems/3sum-with-multiplicity/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-array-by-parity-ii "Sort Array By Parity II")
-　　　　　　　　　　　　　　　　
-[Next >](../minimize-malware-spread "Minimize Malware Spread")
-
-## [923. 3Sum With Multiplicity (Medium)](https://leetcode.com/problems/3sum-with-multiplicity "三数之和的多种可能")
-
-<p>Given an integer array <code>arr</code>, and an integer <code>target</code>, return the number of tuples <code>i, j, k</code> such that <code>i &lt; j &lt; k</code> and <code>arr[i] + arr[j] + arr[k] == target</code>.</p>
-
-<p>As the answer can be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,1,2,2,3,3,4,4,5,5], target = 8
-<strong>Output:</strong> 20
-<strong>Explanation: </strong>
-Enumerating by the values (arr[i], arr[j], arr[k]):
-(1, 2, 5) occurs 8 times;
-(1, 3, 4) occurs 8 times;
-(2, 2, 4) occurs 2 times;
-(2, 3, 3) occurs 2 times.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,1,2,2,2,2], target = 5
-<strong>Output:</strong> 12
-<strong>Explanation: </strong>
-arr[i] = 1, arr[j] = arr[k] = 2 occurs 12 times:
-We choose one 1 from [1,1] in 2 ways,
-and two 2s from [2,2,2,2] in 6 ways.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= arr.length &lt;= 3000</code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 100</code></li>
-	<li><code>0 &lt;= target &lt;= 300</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/3sum/3sum.go b/problems/3sum/3sum.go
deleted file mode 100644
index 4a9e0f62c..000000000
--- a/problems/3sum/3sum.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem15
-
-import "sort"
-
-func threeSum(nums []int) [][]int {
-	sort.Ints(nums)
-	ans, length := make([][]int, 0), len(nums)
-	for i := 0; i < length-2; i++ {
-		if nums[i] <= 0 && (i == 0 || nums[i] != nums[i-1]) {
-			l, r := i+1, length-1
-			for l < r {
-				sum := nums[i] + nums[l] + nums[r]
-				if sum < 0 {
-					l++
-				} else if sum > 0 {
-					r--
-				} else {
-					ans = append(ans, []int{nums[i], nums[l], nums[r]})
-					l, r = l+1, r-1
-					for l < r && nums[l] == nums[l-1] {
-						l++
-					}
-					for l < r && nums[r] == nums[r+1] {
-						r--
-					}
-				}
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/3sum/3sum_test.go b/problems/3sum/3sum_test.go
deleted file mode 100644
index fa8763b85..000000000
--- a/problems/3sum/3sum_test.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package problem15
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want [][]int
-}
-
-func TestThreeSum(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: []int{-1, 0, 1, 2, -1, -4},
-			want: [][]int{
-				{-1, -1, 2},
-				{-1, 0, 1},
-			},
-		},
-		{
-			in: []int{0, 0, 0, 0},
-			want: [][]int{
-				{0, 0, 0},
-			},
-		},
-		{
-			in: []int{-2, 0, 0, 2, 2, 2},
-			want: [][]int{
-				{-2, 0, 2},
-			},
-		},
-		{
-			in: []int{-2, 0, 0, 2, 2, 2, 2},
-			want: [][]int{
-				{-2, 0, 2},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := threeSum(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/3sum/README.md b/problems/3sum/README.md
deleted file mode 100644
index 74eb35d4c..000000000
--- a/problems/3sum/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-common-prefix "Longest Common Prefix")
-　　　　　　　　　　　　　　　　
-[Next >](../3sum-closest "3Sum Closest")
-
-## [15. 3Sum (Medium)](https://leetcode.com/problems/3sum "三数之和")
-
-<p>Given an integer array nums, return all the triplets <code>[nums[i], nums[j], nums[k]]</code> such that <code>i != j</code>, <code>i != k</code>, and <code>j != k</code>, and <code>nums[i] + nums[j] + nums[k] == 0</code>.</p>
-
-<p>Notice that the solution set must not contain duplicate triplets.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [-1,0,1,2,-1,-4]
-<strong>Output:</strong> [[-1,-1,2],[-1,0,1]]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = []
-<strong>Output:</strong> []
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [0]
-<strong>Output:</strong> []
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= nums.length &lt;= 3000</code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Two Sum](../two-sum) (Easy)
-  1. [3Sum Closest](../3sum-closest) (Medium)
-  1. [4Sum](../4sum) (Medium)
-  1. [3Sum Smaller](../3sum-smaller) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-So, we essentially need to find three numbers x, y, and z such that they add up to the given value. If we fix one of the numbers say x, we are left with the two-sum problem at hand!
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For the two-sum problem, if we fix one of the numbers, say <pre>x</pre>, we have to scan the entire array to find the next number<pre>y</pre> which is <pre>value - x</pre> where value is the input parameter. Can we change our array somehow so that this search becomes faster?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The second train of thought for two-sum is, without changing the array, can we use additional space somehow? Like maybe a hash map to speed up the search?
-</details>
diff --git a/problems/4-keys-keyboard/4_keys_keyboard.go b/problems/4-keys-keyboard/4_keys_keyboard.go
deleted file mode 100644
index 3dff4fa3d..000000000
--- a/problems/4-keys-keyboard/4_keys_keyboard.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem651
diff --git a/problems/4-keys-keyboard/4_keys_keyboard_test.go b/problems/4-keys-keyboard/4_keys_keyboard_test.go
deleted file mode 100644
index 3dff4fa3d..000000000
--- a/problems/4-keys-keyboard/4_keys_keyboard_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem651
diff --git a/problems/4-keys-keyboard/README.md b/problems/4-keys-keyboard/README.md
deleted file mode 100644
index 14b9a794c..000000000
--- a/problems/4-keys-keyboard/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../2-keys-keyboard "2 Keys Keyboard")
-　　　　　　　　　　　　　　　　
-[Next >](../find-duplicate-subtrees "Find Duplicate Subtrees")
-
-## [651. 4 Keys Keyboard (Medium)](https://leetcode.com/problems/4-keys-keyboard "4键键盘")
-
-<p>Imagine you have a special keyboard with the following keys: </p>
-<p><code>Key 1: (A)</code>:  Print one 'A' on screen.</p>
-<p><code>Key 2: (Ctrl-A)</code>: Select the whole screen.</p>
-<p><code>Key 3: (Ctrl-C)</code>: Copy selection to buffer.</p>
-<p><code>Key 4: (Ctrl-V)</code>: Print buffer on screen appending it after what has already been printed. </p>
-
-
-
-<p>Now, you can only press the keyboard for <b>N</b> times (with the above four keys), find out the maximum numbers of 'A' you can print on screen.</p>
-
-
-<p><b>Example 1:</b><br />
-<pre><b>Input:</b> N = 3
-<b>Output:</b> 3
-<b>Explanation:</b> 
-We can at most get 3 A's on screen by pressing following key sequence:
-A, A, A
-</pre>
-</p>
-
-<p><b>Example 2:</b><br />
-<pre><b>Input:</b> N = 7
-<b>Output:</b> 9
-<b>Explanation:</b> 
-We can at most get 9 A's on screen by pressing following key sequence:
-A, A, A, Ctrl A, Ctrl C, Ctrl V, Ctrl V
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>1 <= N <= 50 </li>
-<li>Answers will be in the range of 32-bit signed integer.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [2 Keys Keyboard](../2-keys-keyboard) (Medium)
diff --git a/problems/4sum-ii/4sum_ii.go b/problems/4sum-ii/4sum_ii.go
deleted file mode 100644
index afe2cf381..000000000
--- a/problems/4sum-ii/4sum_ii.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem454
-
-func fourSumCount(A []int, B []int, C []int, D []int) int {
-	ans, n := 0, len(A)
-	sum := make(map[int]int, n*n)
-	for i := 0; i < n; i++ {
-		for j := 0; j < n; j++ {
-			sum[A[i]+B[j]]++
-		}
-	}
-	for k := 0; k < n; k++ {
-		for l := 0; l < n; l++ {
-			ans += sum[-C[k]-D[l]]
-		}
-	}
-	return ans
-}
diff --git a/problems/4sum-ii/4sum_ii_test.go b/problems/4sum-ii/4sum_ii_test.go
deleted file mode 100644
index ed19e4509..000000000
--- a/problems/4sum-ii/4sum_ii_test.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem454
-
-import "testing"
-
-type testType struct {
-	a    []int
-	b    []int
-	c    []int
-	d    []int
-	want int
-}
-
-func TestFourSumCount(t *testing.T) {
-	tests := [...]testType{
-		{
-			a:    []int{1, 2},
-			b:    []int{-2, -1},
-			c:    []int{-1, 2},
-			d:    []int{0, 2},
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := fourSumCount(tt.a, tt.b, tt.c, tt.d)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt, got, tt.want)
-		}
-	}
-}
diff --git a/problems/4sum-ii/README.md b/problems/4sum-ii/README.md
deleted file mode 100644
index b2fcdb145..000000000
--- a/problems/4sum-ii/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-moves-to-equal-array-elements "Minimum Moves to Equal Array Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../assign-cookies "Assign Cookies")
-
-## [454. 4Sum II (Medium)](https://leetcode.com/problems/4sum-ii "四数相加 II")
-
-<p>Given four integer arrays <code>nums1</code>, <code>nums2</code>, <code>nums3</code>, and <code>nums4</code> all of length <code>n</code>, return the number of tuples <code>(i, j, k, l)</code> such that:</p>
-
-<ul>
-	<li><code>0 &lt;= i, j, k, l &lt; n</code></li>
-	<li><code>nums1[i] + nums2[j] + nums3[k] + nums4[l] == 0</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2], nums2 = [-2,-1], nums3 = [-1,2], nums4 = [0,2]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-The two tuples are:
-1. (0, 0, 0, 1) -&gt; nums1[0] + nums2[0] + nums3[0] + nums4[1] = 1 + (-2) + (-1) + 2 = 0
-2. (1, 1, 0, 0) -&gt; nums1[1] + nums2[1] + nums3[0] + nums4[0] = 2 + (-1) + (-1) + 0 = 0
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [0], nums2 = [0], nums3 = [0], nums4 = [0]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums1.length</code></li>
-	<li><code>n == nums2.length</code></li>
-	<li><code>n == nums3.length</code></li>
-	<li><code>n == nums4.length</code></li>
-	<li><code>1 &lt;= n &lt;= 200</code></li>
-	<li><code>-2<sup>28</sup> &lt;= nums1[i], nums2[i], nums3[i], nums4[i] &lt;= 2<sup>28</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [4Sum](../4sum) (Medium)
diff --git a/problems/4sum/4sum.go b/problems/4sum/4sum.go
deleted file mode 100644
index 290dec515..000000000
--- a/problems/4sum/4sum.go
+++ /dev/null
@@ -1,37 +0,0 @@
-package problem18
-
-import "sort"
-
-func fourSum(nums []int, target int) [][]int {
-	sort.Ints(nums)
-	ans, end := make([][]int, 0), len(nums)-1
-	for i := 0; i < end-2; i++ {
-		if i > 0 && nums[i] == nums[i-1] {
-			continue
-		}
-		for j := i + 1; j < end-1; j++ {
-			if j > i+1 && nums[j] == nums[j-1] {
-				continue
-			}
-			l, r := j+1, end
-			for l < r {
-				sum := nums[i] + nums[j] + nums[l] + nums[r]
-				if sum < target {
-					l++
-				} else if sum > target {
-					r--
-				} else {
-					ans = append(ans, []int{nums[i], nums[j], nums[l], nums[r]})
-					l, r = l+1, r-1
-					for l < r && nums[l] == nums[l-1] {
-						l++
-					}
-					for l < r && nums[r] == nums[r+1] {
-						r--
-					}
-				}
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/4sum/4sum_test.go b/problems/4sum/4sum_test.go
deleted file mode 100644
index 183b928e6..000000000
--- a/problems/4sum/4sum_test.go
+++ /dev/null
@@ -1,81 +0,0 @@
-package problem18
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in     []int
-	target int
-	want   [][]int
-}
-
-func TestFourSum(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:     []int{1, 0, -1, 0, -2, 2},
-			target: 0,
-			want: [][]int{
-				{-2, -1, 1, 2},
-				{-2, 0, 0, 2},
-				{-1, 0, 0, 1},
-			},
-		},
-		{
-			in:     []int{-1, 0, 1, 2, -1, -4},
-			target: 0,
-			want: [][]int{
-				{-1, -1, 0, 2},
-			},
-		},
-		{
-			in:     []int{0, 0, 0, 0},
-			target: 0,
-			want: [][]int{
-				{0, 0, 0, 0},
-			},
-		},
-		{
-			in:     []int{-2, 0, 0, 2, 2, 2},
-			target: 0,
-			want: [][]int{
-				{-2, 0, 0, 2},
-			},
-		},
-		{
-			in:     []int{-2, 0, 0, 2, 2, 2, 2},
-			target: 0,
-			want: [][]int{
-				{-2, 0, 0, 2},
-			},
-		},
-		{
-			in:     []int{-3, -2, -1, 0, 0, 1, 2, 3},
-			target: 0,
-			want: [][]int{
-				{-3, -2, 2, 3},
-				{-3, -1, 1, 3},
-				{-3, 0, 0, 3},
-				{-3, 0, 1, 2},
-				{-2, -1, 0, 3},
-				{-2, -1, 1, 2},
-				{-2, 0, 0, 2},
-				{-1, 0, 0, 1},
-			},
-		},
-		{
-			in:     []int{1, -2, -5, -4, -3, 3, 3, 5},
-			target: -11,
-			want: [][]int{
-				{-5, -4, -3, 1},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := fourSum(tt.in, tt.target)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/4sum/README.md b/problems/4sum/README.md
deleted file mode 100644
index cbf87def4..000000000
--- a/problems/4sum/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../letter-combinations-of-a-phone-number "Letter Combinations of a Phone Number")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-nth-node-from-end-of-list "Remove Nth Node From End of List")
-
-## [18. 4Sum (Medium)](https://leetcode.com/problems/4sum "四数之和")
-
-<p>Given an array <code>nums</code> of <code>n</code> integers, return <em>an array of all the <strong>unique</strong> quadruplets</em> <code>[nums[a], nums[b], nums[c], nums[d]]</code> such that:</p>
-
-<ul>
-	<li><code>0 &lt;= a, b, c, d&nbsp;&lt; n</code></li>
-	<li><code>a</code>, <code>b</code>, <code>c</code>, and <code>d</code> are <strong>distinct</strong>.</li>
-	<li><code>nums[a] + nums[b] + nums[c] + nums[d] == target</code></li>
-</ul>
-
-<p>You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,0,-1,0,-2,2], target = 0
-<strong>Output:</strong> [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,2,2,2], target = 8
-<strong>Output:</strong> [[2,2,2,2]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 200</code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= target &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Two Sum](../two-sum) (Easy)
-  1. [3Sum](../3sum) (Medium)
-  1. [4Sum II](../4sum-ii) (Medium)
-  1. [Count Special Quadruplets](../count-special-quadruplets) (Easy)
diff --git a/problems/a-number-after-a-double-reversal/README.md b/problems/a-number-after-a-double-reversal/README.md
deleted file mode 100644
index 4fffcb4b3..000000000
--- a/problems/a-number-after-a-double-reversal/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../build-the-equation "Build the Equation")
-　　　　　　　　　　　　　　　　
-[Next >](../execution-of-all-suffix-instructions-staying-in-a-grid "Execution of All Suffix Instructions Staying in a Grid")
-
-## [2119. A Number After a Double Reversal (Easy)](https://leetcode.com/problems/a-number-after-a-double-reversal "反转两次的数字")
-
-<p><strong>Reversing</strong> an integer means to reverse all its digits.</p>
-
-<ul>
-	<li>For example, reversing <code>2021</code> gives <code>1202</code>. Reversing <code>12300</code> gives <code>321</code> as the <strong>leading zeros are not retained</strong>.</li>
-</ul>
-
-<p>Given an integer <code>num</code>, <strong>reverse</strong> <code>num</code> to get <code>reversed1</code>, <strong>then reverse</strong> <code>reversed1</code> to get <code>reversed2</code>. Return <code>true</code> <em>if</em> <code>reversed2</code> <em>equals</em> <code>num</code>. Otherwise return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 526
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Reverse num to get 625, then reverse 625 to get 526, which equals num.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 1800
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Reverse num to get 81, then reverse 81 to get 18, which does not equal num.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 0
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Reverse num to get 0, then reverse 0 to get 0, which equals num.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= num &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Other than the number 0 itself, any number that ends with 0 would lose some digits permanently when reversed.
-</details>
diff --git a/problems/abbreviating-the-product-of-a-range/README.md b/problems/abbreviating-the-product-of-a-range/README.md
deleted file mode 100644
index 3ee8a1c74..000000000
--- a/problems/abbreviating-the-product-of-a-range/README.md
+++ /dev/null
@@ -1,103 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-a-parentheses-string-can-be-valid "Check if a Parentheses String Can Be Valid")
-　　　　　　　　　　　　　　　　
-[Next >](../build-the-equation "Build the Equation")
-
-## [2117. Abbreviating the Product of a Range (Hard)](https://leetcode.com/problems/abbreviating-the-product-of-a-range "一个区间内所有数乘积的缩写")
-
-<p>You are given two positive integers <code>left</code> and <code>right</code> with <code>left &lt;= right</code>. Calculate the <strong>product</strong> of all integers in the <strong>inclusive</strong> range <code>[left, right]</code>.</p>
-
-<p>Since the product may be very large, you will <strong>abbreviate</strong> it following these steps:</p>
-
-<ol>
-	<li>Count all <strong>trailing</strong> zeros in the product and <strong>remove</strong> them. Let us denote this count as <code>C</code>.
-	<ul>
-		<li>For example, there are <code>3</code> trailing zeros in <code>1000</code>, and there are <code>0</code> trailing zeros in <code>546</code>.</li>
-	</ul>
-	</li>
-	<li>Denote the remaining number of digits in the product as <code>d</code>. If <code>d &gt; 10</code>, then express the product as <code>&lt;pre&gt;...&lt;suf&gt;</code> where <code>&lt;pre&gt;</code> denotes the <strong>first</strong> <code>5</code> digits of the product, and <code>&lt;suf&gt;</code> denotes the <strong>last</strong> <code>5</code> digits of the product <strong>after</strong> removing all trailing zeros. If <code>d &lt;= 10</code>, we keep it unchanged.
-	<ul>
-		<li>For example, we express <code>1234567654321</code> as <code>12345...54321</code>, but <code>1234567</code> is represented as <code>1234567</code>.</li>
-	</ul>
-	</li>
-	<li>Finally, represent the product as a <strong>string</strong> <code>&quot;&lt;pre&gt;...&lt;suf&gt;eC&quot;</code>.
-	<ul>
-		<li>For example, <code>12345678987600000</code> will be represented as <code>&quot;12345...89876e5&quot;</code>.</li>
-	</ul>
-	</li>
-</ol>
-
-<p>Return <em>a string denoting the <strong>abbreviated product</strong> of all integers in the <strong>inclusive</strong> range</em> <code>[left, right]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = 1, right = 4
-<strong>Output:</strong> &quot;24e0&quot;
-<strong>Explanation:</strong> The product is 1 &times; 2 &times; 3 &times; 4 = 24.
-There are no trailing zeros, so 24 remains the same. The abbreviation will end with &quot;e0&quot;.
-Since the number of digits is 2, which is less than 10, we do not have to abbreviate it further.
-Thus, the final representation is &quot;24e0&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = 2, right = 11
-<strong>Output:</strong> &quot;399168e2&quot;
-<strong>Explanation:</strong> The product is 39916800.
-There are 2 trailing zeros, which we remove to get 399168. The abbreviation will end with &quot;e2&quot;.
-The number of digits after removing the trailing zeros is 6, so we do not abbreviate it further.
-Hence, the abbreviated product is &quot;399168e2&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = 371, right = 375
-<strong>Output:</strong> &quot;7219856259e3&quot;
-<strong>Explanation:</strong> The product is 7219856259000.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= left &lt;= right &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Calculating the number of trailing zeros, the last five digits, and the first five digits can all be done separately.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a prime factorization property to find the number of trailing zeros. Use modulo to find the last 5 digits. Use a logarithm property to find the first 5 digits.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The number of trailing zeros C is nothing but the number of times the product is completely divisible by 10. Since 2 and 5 are the only prime factors of 10,  C will be equal to the minimum number of times 2 or 5 appear in the prime factorization of the product.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Iterate through the integers from left to right. For every integer, keep dividing it by 2 as long as it is divisible by 2 and C occurrences of 2 haven't been removed in total. Repeat this process for 5. Finally, multiply the integer under modulo of 10^5 with the product obtained till now to obtain the last five digits.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-The product P can be represented as P=10^(x+y) where x is the integral part and y is the fractional part of x+y. Using the property "if S = A * B, then log(S) = log(A) + log(B)", we can write x+y = log_10(P) = sum(log_10(i)) for each integer i in [left, right]. Once we obtain the sum, the first five digits can be represented as floor(10^(y+4)).
-</details>
diff --git a/problems/accepted-candidates-from-the-interviews/README.md b/problems/accepted-candidates-from-the-interviews/README.md
deleted file mode 100644
index b6aa925d5..000000000
--- a/problems/accepted-candidates-from-the-interviews/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-smallest-product-of-two-sorted-arrays "Kth Smallest Product of Two Sorted Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-numbers-are-ascending-in-a-sentence "Check if Numbers Are Ascending in a Sentence")
-
-## [2041. Accepted Candidates From the Interviews (Medium)](https://leetcode.com/problems/accepted-candidates-from-the-interviews "面试中被录取的候选人")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/accepted-candidates-from-the-interviews/mysql_schemas.sql b/problems/accepted-candidates-from-the-interviews/mysql_schemas.sql
deleted file mode 100644
index 6d1a6a9d4..000000000
--- a/problems/accepted-candidates-from-the-interviews/mysql_schemas.sql
+++ /dev/null
@@ -1,20 +0,0 @@
-Create table If Not Exists Candidates (candidate_id int, name varchar(30), years_of_exp int, interview_id int);
-Create table If Not Exists Rounds (interview_id int, round_id int, score int);
-Truncate table Candidates;
-insert into Candidates (candidate_id, name, years_of_exp, interview_id) values ('11', 'Atticus', '1', '101');
-insert into Candidates (candidate_id, name, years_of_exp, interview_id) values ('9', 'Ruben', '6', '104');
-insert into Candidates (candidate_id, name, years_of_exp, interview_id) values ('6', 'Aliza', '10', '109');
-insert into Candidates (candidate_id, name, years_of_exp, interview_id) values ('8', 'Alfredo', '0', '107');
-Truncate table Rounds;
-insert into Rounds (interview_id, round_id, score) values ('109', '3', '4');
-insert into Rounds (interview_id, round_id, score) values ('101', '2', '8');
-insert into Rounds (interview_id, round_id, score) values ('109', '4', '1');
-insert into Rounds (interview_id, round_id, score) values ('107', '1', '3');
-insert into Rounds (interview_id, round_id, score) values ('104', '3', '6');
-insert into Rounds (interview_id, round_id, score) values ('109', '1', '4');
-insert into Rounds (interview_id, round_id, score) values ('104', '4', '7');
-insert into Rounds (interview_id, round_id, score) values ('104', '1', '2');
-insert into Rounds (interview_id, round_id, score) values ('109', '2', '1');
-insert into Rounds (interview_id, round_id, score) values ('104', '2', '7');
-insert into Rounds (interview_id, round_id, score) values ('107', '2', '3');
-insert into Rounds (interview_id, round_id, score) values ('101', '1', '8');
diff --git a/problems/account-balance/README.md b/problems/account-balance/README.md
deleted file mode 100644
index a5dbfabc3..000000000
--- a/problems/account-balance/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-path-quality-of-a-graph "Maximum Path Quality of a Graph")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-equal-count-substrings "Number of Equal Count Substrings")
-
-## [2066. Account Balance (Medium)](https://leetcode.com/problems/account-balance "账户余额")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/account-balance/mysql_schemas.sql b/problems/account-balance/mysql_schemas.sql
deleted file mode 100644
index 74d4a5114..000000000
--- a/problems/account-balance/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Transactions (account_id int, day date, type ENUM('Deposit', 'Withdraw'), amount int);
-Truncate table Transactions;
-insert into Transactions (account_id, day, type, amount) values ('1', '2021-11-07', 'Deposit', '2000');
-insert into Transactions (account_id, day, type, amount) values ('1', '2021-11-09', 'Withdraw', '1000');
-insert into Transactions (account_id, day, type, amount) values ('1', '2021-11-11', 'Deposit', '3000');
-insert into Transactions (account_id, day, type, amount) values ('2', '2021-12-07', 'Deposit', '7000');
-insert into Transactions (account_id, day, type, amount) values ('2', '2021-12-12', 'Withdraw', '7000');
diff --git a/problems/accounts-merge/README.md b/problems/accounts-merge/README.md
deleted file mode 100644
index 63f2c14d2..000000000
--- a/problems/accounts-merge/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-word-in-dictionary "Longest Word in Dictionary")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-comments "Remove Comments")
-
-## [721. Accounts Merge (Medium)](https://leetcode.com/problems/accounts-merge "账户合并")
-
-<p>Given a list of <code>accounts</code> where each element <code>accounts[i]</code> is a list of strings, where the first element <code>accounts[i][0]</code> is a name, and the rest of the elements are <strong>emails</strong> representing emails of the account.</p>
-
-<p>Now, we would like to merge these accounts. Two accounts definitely belong to the same person if there is some common email to both accounts. Note that even if two accounts have the same name, they may belong to different people as people could have the same name. A person can have any number of accounts initially, but all of their accounts definitely have the same name.</p>
-
-<p>After merging the accounts, return the accounts in the following format: the first element of each account is the name, and the rest of the elements are emails <strong>in sorted order</strong>. The accounts themselves can be returned in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> accounts = [[&quot;John&quot;,&quot;johnsmith@mail.com&quot;,&quot;john_newyork@mail.com&quot;],[&quot;John&quot;,&quot;johnsmith@mail.com&quot;,&quot;john00@mail.com&quot;],[&quot;Mary&quot;,&quot;mary@mail.com&quot;],[&quot;John&quot;,&quot;johnnybravo@mail.com&quot;]]
-<strong>Output:</strong> [[&quot;John&quot;,&quot;john00@mail.com&quot;,&quot;john_newyork@mail.com&quot;,&quot;johnsmith@mail.com&quot;],[&quot;Mary&quot;,&quot;mary@mail.com&quot;],[&quot;John&quot;,&quot;johnnybravo@mail.com&quot;]]
-<strong>Explanation:</strong>
-The first and second John&#39;s are the same person as they have the common email &quot;johnsmith@mail.com&quot;.
-The third John and Mary are different people as none of their email addresses are used by other accounts.
-We could return these lists in any order, for example the answer [[&#39;Mary&#39;, &#39;mary@mail.com&#39;], [&#39;John&#39;, &#39;johnnybravo@mail.com&#39;], 
-[&#39;John&#39;, &#39;john00@mail.com&#39;, &#39;john_newyork@mail.com&#39;, &#39;johnsmith@mail.com&#39;]] would still be accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> accounts = [[&quot;Gabe&quot;,&quot;Gabe0@m.co&quot;,&quot;Gabe3@m.co&quot;,&quot;Gabe1@m.co&quot;],[&quot;Kevin&quot;,&quot;Kevin3@m.co&quot;,&quot;Kevin5@m.co&quot;,&quot;Kevin0@m.co&quot;],[&quot;Ethan&quot;,&quot;Ethan5@m.co&quot;,&quot;Ethan4@m.co&quot;,&quot;Ethan0@m.co&quot;],[&quot;Hanzo&quot;,&quot;Hanzo3@m.co&quot;,&quot;Hanzo1@m.co&quot;,&quot;Hanzo0@m.co&quot;],[&quot;Fern&quot;,&quot;Fern5@m.co&quot;,&quot;Fern1@m.co&quot;,&quot;Fern0@m.co&quot;]]
-<strong>Output:</strong> [[&quot;Ethan&quot;,&quot;Ethan0@m.co&quot;,&quot;Ethan4@m.co&quot;,&quot;Ethan5@m.co&quot;],[&quot;Gabe&quot;,&quot;Gabe0@m.co&quot;,&quot;Gabe1@m.co&quot;,&quot;Gabe3@m.co&quot;],[&quot;Hanzo&quot;,&quot;Hanzo0@m.co&quot;,&quot;Hanzo1@m.co&quot;,&quot;Hanzo3@m.co&quot;],[&quot;Kevin&quot;,&quot;Kevin0@m.co&quot;,&quot;Kevin3@m.co&quot;,&quot;Kevin5@m.co&quot;],[&quot;Fern&quot;,&quot;Fern0@m.co&quot;,&quot;Fern1@m.co&quot;,&quot;Fern5@m.co&quot;]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= accounts.length &lt;= 1000</code></li>
-	<li><code>2 &lt;= accounts[i].length &lt;= 10</code></li>
-	<li><code>1 &lt;= accounts[i][j] &lt;= 30</code></li>
-	<li><code>accounts[i][0]</code> consists of English letters.</li>
-	<li><code>accounts[i][j] (for j &gt; 0)</code> is a valid email.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Redundant Connection](../redundant-connection) (Medium)
-  1. [Sentence Similarity](../sentence-similarity) (Easy)
-  1. [Sentence Similarity II](../sentence-similarity-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For every pair of emails in the same account, draw an edge between those emails.  The problem is about enumerating the connected components of this graph.
-</details>
diff --git a/problems/accounts-merge/accounts_merge.go b/problems/accounts-merge/accounts_merge.go
deleted file mode 100644
index 2783a6b2a..000000000
--- a/problems/accounts-merge/accounts_merge.go
+++ /dev/null
@@ -1,45 +0,0 @@
-package problem721
-
-import "sort"
-
-func accountsMerge(accounts [][]string) [][]string {
-	n := len(accounts)
-	owner := make(map[string]string, n)
-	parent := make(map[string]string, n*2)
-	for _, a := range accounts {
-		for i := 1; i < len(a); i++ {
-			parent[a[i]] = a[i]
-			owner[a[i]] = a[0]
-		}
-	}
-	for _, a := range accounts {
-		r := root(a[1], parent)
-		for i := 2; i < len(a); i++ {
-			p := root(a[i], parent)
-			parent[p] = r
-		}
-	}
-	union := make(map[string][]string, n)
-	for email, p := range parent {
-		r := root(p, parent)
-		union[r] = append(union[r], email)
-	}
-	res := make([][]string, 0, len(union))
-	for p, emails := range union {
-		t := make([]string, len(emails)+1)
-		t[0] = owner[p]
-		if len(emails) > 1 {
-			sort.Strings(emails)
-		}
-		copy(t[1:], emails)
-		res = append(res, t)
-	}
-	return res
-}
-
-func root(e string, parent map[string]string) string {
-	if parent[e] == e {
-		return e
-	}
-	return root(parent[e], parent)
-}
diff --git a/problems/accounts-merge/accounts_merge_test.go b/problems/accounts-merge/accounts_merge_test.go
deleted file mode 100644
index e95d5d934..000000000
--- a/problems/accounts-merge/accounts_merge_test.go
+++ /dev/null
@@ -1,81 +0,0 @@
-package problem721
-
-import (
-	"reflect"
-	"sort"
-	"testing"
-)
-
-type testType struct {
-	in   [][]string
-	want [][]string
-}
-
-func TestAccountsMerge(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]string{
-				{"John", "johnsmith@mail.com", "john00@mail.com"},
-				{"John", "johnnybravo@mail.com"},
-				{"John", "johnsmith@mail.com", "john_newyork@mail.com"},
-				{"Mary", "mary@mail.com"},
-			},
-			want: [][]string{
-				{"John", "john00@mail.com", "john_newyork@mail.com", "johnsmith@mail.com"},
-				{"John", "johnnybravo@mail.com"},
-				{"Mary", "mary@mail.com"},
-			},
-		},
-		{
-			in: [][]string{
-				{"Alex", "Alex5@m.co", "Alex4@m.co", "Alex0@m.co"},
-				{"Ethan", "Ethan3@m.co", "Ethan3@m.co", "Ethan0@m.co"},
-				{"Kevin", "Kevin4@m.co", "Kevin2@m.co", "Kevin2@m.co"},
-				{"Gabe", "Gabe0@m.co", "Gabe3@m.co", "Gabe2@m.co"},
-				{"Gabe", "Gabe3@m.co", "Gabe4@m.co", "Gabe2@m.co"},
-			},
-			want: [][]string{
-				{"Alex", "Alex0@m.co", "Alex4@m.co", "Alex5@m.co"},
-				{"Ethan", "Ethan0@m.co", "Ethan3@m.co"},
-				{"Gabe", "Gabe0@m.co", "Gabe2@m.co", "Gabe3@m.co", "Gabe4@m.co"},
-				{"Kevin", "Kevin2@m.co", "Kevin4@m.co"},
-			},
-		},
-		{
-			in: [][]string{
-				{"David", "David0@m.co", "David4@m.co", "David3@m.co"},
-				{"David", "David5@m.co", "David5@m.co", "David0@m.co"},
-				{"David", "David1@m.co", "David4@m.co", "David0@m.co"},
-				{"David", "David0@m.co", "David1@m.co", "David3@m.co"},
-				{"David", "David4@m.co", "David1@m.co", "David3@m.co"},
-			},
-			want: [][]string{
-				{"David", "David0@m.co", "David1@m.co", "David3@m.co", "David4@m.co", "David5@m.co"},
-			},
-		},
-		{
-			in: [][]string{
-				{"David", "David0@m.co", "David1@m.co"},
-				{"David", "David3@m.co", "David4@m.co"},
-				{"David", "David4@m.co", "David5@m.co"},
-				{"David", "David2@m.co", "David3@m.co"},
-				{"David", "David1@m.co", "David2@m.co"},
-			},
-			want: [][]string{
-				{"David", "David0@m.co", "David1@m.co", "David2@m.co", "David3@m.co", "David4@m.co", "David5@m.co"},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := accountsMerge(tt.in)
-		sort.Slice(got, func(i, j int) bool {
-			if got[i][0] == got[i][0] {
-				return got[i][1] < got[j][1]
-			}
-			return got[i][0] < got[i][0]
-		})
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/active-businesses/README.md b/problems/active-businesses/README.md
deleted file mode 100644
index 0502a4f42..000000000
--- a/problems/active-businesses/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-sufficient-team "Smallest Sufficient Team")
-　　　　　　　　　　　　　　　　
-[Next >](../user-purchase-platform "User Purchase Platform")
-
-## [1126. Active Businesses (Medium)](https://leetcode.com/problems/active-businesses "查询活跃业务")
-
-<p>Table: <code>Events</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| business_id   | int     |
-| event_type    | varchar |
-| occurences    | int     | 
-+---------------+---------+
-(business_id, event_type) is the primary key of this table.
-Each row in the table logs the info that an event of some type occured at some business for a number of times.</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find all <em>active businesses</em>.</p>
-
-<p>An active business is a business that has more than one event type&nbsp;with occurences greater than the average occurences of that event type&nbsp;among all businesses.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Events table:
-+-------------+------------+------------+
-| business_id | event_type | occurences |
-+-------------+------------+------------+
-| 1           | reviews    | 7          |
-| 3           | reviews    | 3          |
-| 1           | ads        | 11         |
-| 2           | ads        | 7          |
-| 3           | ads        | 6          |
-| 1           | page views | 3          |
-| 2           | page views | 12         |
-+-------------+------------+------------+
-
-Result table:
-+-------------+
-| business_id |
-+-------------+
-| 1           |
-+-------------+ 
-Average for &#39;reviews&#39;, &#39;ads&#39; and &#39;page views&#39; are (7+3)/2=5, (11+7+6)/3=8, (3+12)/2=7.5 respectively.
-Business with id 1 has 7 &#39;reviews&#39; events (more than 5) and 11 &#39;ads&#39; events (more than 8) so it is an active business.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/active-businesses/active_businesses.sql b/problems/active-businesses/active_businesses.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/active-businesses/active_businesses.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/active-businesses/mysql_schemas.sql b/problems/active-businesses/mysql_schemas.sql
deleted file mode 100644
index b80874bf4..000000000
--- a/problems/active-businesses/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Events (business_id int, event_type varchar(10), occurences int);
-Truncate table Events;
-insert into Events (business_id, event_type, occurences) values ('1', 'reviews', '7');
-insert into Events (business_id, event_type, occurences) values ('3', 'reviews', '3');
-insert into Events (business_id, event_type, occurences) values ('1', 'ads', '11');
-insert into Events (business_id, event_type, occurences) values ('2', 'ads', '7');
-insert into Events (business_id, event_type, occurences) values ('3', 'ads', '6');
-insert into Events (business_id, event_type, occurences) values ('1', 'page views', '3');
-insert into Events (business_id, event_type, occurences) values ('2', 'page views', '12');
diff --git a/problems/active-users/README.md b/problems/active-users/README.md
deleted file mode 100644
index ef8762c21..000000000
--- a/problems/active-users/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-darts-inside-of-a-circular-dartboard "Maximum Number of Darts Inside of a Circular Dartboard")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence "Check If a Word Occurs As a Prefix of Any Word in a Sentence")
-
-## [1454. Active Users (Medium)](https://leetcode.com/problems/active-users "活跃用户")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/active-users/mysql_schemas.sql b/problems/active-users/mysql_schemas.sql
deleted file mode 100644
index 256bf8be8..000000000
--- a/problems/active-users/mysql_schemas.sql
+++ /dev/null
@@ -1,15 +0,0 @@
-Create table If Not Exists Accounts (id int, name varchar(10));
-Create table If Not Exists Logins (id int, login_date date);
-Truncate table Accounts;
-insert into Accounts (id, name) values ('1', 'Winston');
-insert into Accounts (id, name) values ('7', 'Jonathan');
-Truncate table Logins;
-insert into Logins (id, login_date) values ('7', '2020-05-30');
-insert into Logins (id, login_date) values ('1', '2020-05-30');
-insert into Logins (id, login_date) values ('7', '2020-05-31');
-insert into Logins (id, login_date) values ('7', '2020-06-01');
-insert into Logins (id, login_date) values ('7', '2020-06-02');
-insert into Logins (id, login_date) values ('7', '2020-06-02');
-insert into Logins (id, login_date) values ('7', '2020-06-03');
-insert into Logins (id, login_date) values ('1', '2020-06-07');
-insert into Logins (id, login_date) values ('7', '2020-06-10');
diff --git a/problems/activity-participants/README.md b/problems/activity-participants/README.md
deleted file mode 100644
index 066be853b..000000000
--- a/problems/activity-participants/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-target-array-with-multiple-sums "Construct Target Array With Multiple Sums")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-integers-by-the-number-of-1-bits "Sort Integers by The Number of 1 Bits")
-
-## [1355. Activity Participants (Medium)](https://leetcode.com/problems/activity-participants "活动参与者")
-
-<p>Table: <code>Friends</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| name          | varchar |
-| activity      | varchar |
-+---------------+---------+
-id is the id of the friend and primary key for this table.
-name is the name of the friend.
-activity is the name of the activity which the friend takes part in.
-</pre>
-
-<p>Table: <code>Activities</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| name          | varchar |
-+---------------+---------+
-id is the primary key for this table.
-name is the name of the activity.
-</pre>
- 
-Write an SQL query to find the names of all the activities with neither maximum, nor minimum number of participants.
-
-Return the result table in any order. Each activity in table Activities is performed by any person in the table Friends.
-
-The query result format is in the following example:
-
-Friends table:
-<pre>
-+------+--------------+---------------+
-| id   | name         | activity      |
-+------+--------------+---------------+
-| 1    | Jonathan D.  | Eating        |
-| 2    | Jade W.      | Singing       |
-| 3    | Victor J.    | Singing       |
-| 4    | Elvis Q.     | Eating        |
-| 5    | Daniel A.    | Eating        |
-| 6    | Bob B.       | Horse Riding  |
-+------+--------------+---------------+
-
-Activities table:
-+------+--------------+
-| id   | name         |
-+------+--------------+
-| 1    | Eating       |
-| 2    | Singing      |
-| 3    | Horse Riding |
-+------+--------------+
-
-Result table:
-+--------------+
-| results      |
-+--------------+
-| Singing      |
-+--------------+
-
-Eating activity is performed by 3 friends, maximum number of participants, (Jonathan D. , Elvis Q. and Daniel A.)
-Horse Riding activity is performed by 1 friend, minimum number of participants, (Bob B.)
-Singing is performed by 2 friends (Victor J. and Jade W.)
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/activity-participants/mysql_schemas.sql b/problems/activity-participants/mysql_schemas.sql
deleted file mode 100644
index 161ef2e28..000000000
--- a/problems/activity-participants/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Friends (id int, name varchar(30), activity varchar(30));
-Create table If Not Exists Activities (id int, name varchar(30));
-Truncate table Friends;
-insert into Friends (id, name, activity) values ('1', 'Jonathan D.', 'Eating');
-insert into Friends (id, name, activity) values ('2', 'Jade W.', 'Singing');
-insert into Friends (id, name, activity) values ('3', 'Victor J.', 'Singing');
-insert into Friends (id, name, activity) values ('4', 'Elvis Q.', 'Eating');
-insert into Friends (id, name, activity) values ('5', 'Daniel A.', 'Eating');
-insert into Friends (id, name, activity) values ('6', 'Bob B.', 'Horse Riding');
-Truncate table Activities;
-insert into Activities (id, name) values ('1', 'Eating');
-insert into Activities (id, name) values ('2', 'Singing');
-insert into Activities (id, name) values ('3', 'Horse Riding');
diff --git a/problems/actors-and-directors-who-cooperated-at-least-three-times/README.md b/problems/actors-and-directors-who-cooperated-at-least-three-times/README.md
deleted file mode 100644
index 553490bae..000000000
--- a/problems/actors-and-directors-who-cooperated-at-least-three-times/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../last-stone-weight-ii "Last Stone Weight II")
-　　　　　　　　　　　　　　　　
-[Next >](../height-checker "Height Checker")
-
-## [1050. Actors and Directors Who Cooperated At Least Three Times (Easy)](https://leetcode.com/problems/actors-and-directors-who-cooperated-at-least-three-times "合作过至少三次的演员和导演")
-
-<p>Table: <code>ActorDirector</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| actor_id    | int     |
-| director_id | int     |
-| timestamp   | int     |
-+-------------+---------+
-timestamp is the primary key column for this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write a SQL query for a report that provides the pairs <code>(actor_id, director_id)</code> where the actor have cooperated with the director at least 3 times.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-ActorDirector table:
-+-------------+-------------+-------------+
-| actor_id    | director_id | timestamp   |
-+-------------+-------------+-------------+
-| 1           | 1           | 0           |
-| 1           | 1           | 1           |
-| 1           | 1           | 2           |
-| 1           | 2           | 3           |
-| 1           | 2           | 4           |
-| 2           | 1           | 5           |
-| 2           | 1           | 6           |
-+-------------+-------------+-------------+
-
-Result table:
-+-------------+-------------+
-| actor_id    | director_id |
-+-------------+-------------+
-| 1           | 1           |
-+-------------+-------------+
-The only pair is (1, 1) where they cooperated exactly 3 times.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/actors-and-directors-who-cooperated-at-least-three-times/actors_and_directors_who_cooperated_at_least_three_times.sql b/problems/actors-and-directors-who-cooperated-at-least-three-times/actors_and_directors_who_cooperated_at_least_three_times.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/actors-and-directors-who-cooperated-at-least-three-times/actors_and_directors_who_cooperated_at_least_three_times.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/actors-and-directors-who-cooperated-at-least-three-times/mysql_schemas.sql b/problems/actors-and-directors-who-cooperated-at-least-three-times/mysql_schemas.sql
deleted file mode 100644
index 39c505012..000000000
--- a/problems/actors-and-directors-who-cooperated-at-least-three-times/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists ActorDirector (actor_id int, director_id int, timestamp int);
-Truncate table ActorDirector;
-insert into ActorDirector (actor_id, director_id, timestamp) values ('1', '1', '0');
-insert into ActorDirector (actor_id, director_id, timestamp) values ('1', '1', '1');
-insert into ActorDirector (actor_id, director_id, timestamp) values ('1', '1', '2');
-insert into ActorDirector (actor_id, director_id, timestamp) values ('1', '2', '3');
-insert into ActorDirector (actor_id, director_id, timestamp) values ('1', '2', '4');
-insert into ActorDirector (actor_id, director_id, timestamp) values ('2', '1', '5');
-insert into ActorDirector (actor_id, director_id, timestamp) values ('2', '1', '6');
diff --git a/problems/ad-free-sessions/README.md b/problems/ad-free-sessions/README.md
deleted file mode 100644
index 4e9bc9677..000000000
--- a/problems/ad-free-sessions/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximize-number-of-nice-divisors "Maximize Number of Nice Divisors")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-path-cost-in-a-hidden-grid "Minimum Path Cost in a Hidden Grid")
-
-## [1809. Ad-Free Sessions (Easy)](https://leetcode.com/problems/ad-free-sessions "没有广告的剧集")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/ad-free-sessions/mysql_schemas.sql b/problems/ad-free-sessions/mysql_schemas.sql
deleted file mode 100644
index f430ed831..000000000
--- a/problems/ad-free-sessions/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Playback(session_id int,customer_id int,start_time int,end_time int);
-Create table If Not Exists Ads (ad_id int, customer_id int, timestamp int);
-Truncate table Playback;
-insert into Playback (session_id, customer_id, start_time, end_time) values ('1', '1', '1', '5');
-insert into Playback (session_id, customer_id, start_time, end_time) values ('2', '1', '15', '23');
-insert into Playback (session_id, customer_id, start_time, end_time) values ('3', '2', '10', '12');
-insert into Playback (session_id, customer_id, start_time, end_time) values ('4', '2', '17', '28');
-insert into Playback (session_id, customer_id, start_time, end_time) values ('5', '2', '2', '8');
-Truncate table Ads;
-insert into Ads (ad_id, customer_id, timestamp) values ('1', '1', '5');
-insert into Ads (ad_id, customer_id, timestamp) values ('2', '2', '17');
-insert into Ads (ad_id, customer_id, timestamp) values ('3', '2', '20');
diff --git a/problems/add-and-search-word-data-structure-design/README.md b/problems/add-and-search-word-data-structure-design/README.md
deleted file mode 100644
index 2376f5791..000000000
--- a/problems/add-and-search-word-data-structure-design/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../course-schedule-ii "Course Schedule II")
-　　　　　　　　　　　　　　　　
-[Next >](../word-search-ii "Word Search II")
-
-## [211. Add and Search Word - Data structure design (Medium)](https://leetcode.com/problems/add-and-search-word-data-structure-design "添加与搜索单词 - 数据结构设计")
-
-<p>Design a data structure that supports the following two operations:</p>
-
-<pre>
-void addWord(word)
-bool search(word)
-</pre>
-
-<p>search(word) can search a literal word or a regular expression string containing only letters <code>a-z</code> or <code>.</code>. A <code>.</code> means it can represent any one letter.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-addWord(&quot;bad&quot;)
-addWord(&quot;dad&quot;)
-addWord(&quot;mad&quot;)
-search(&quot;pad&quot;) -&gt; false
-search(&quot;bad&quot;) -&gt; true
-search(&quot;.ad&quot;) -&gt; true
-search(&quot;b..&quot;) -&gt; true
-</pre>
-
-<p><b>Note:</b><br />
-You may assume that all words are consist of lowercase letters <code>a-z</code>.</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Implement Trie (Prefix Tree)](../implement-trie-prefix-tree) (Medium)
-  1. [Prefix and Suffix Search](../prefix-and-suffix-search) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You should be familiar with how a Trie works. If not, please work on this problem: <a href="https://leetcode.com/problems/implement-trie-prefix-tree/">Implement Trie (Prefix Tree)</a> first.
-</details>
diff --git a/problems/add-and-search-word-data-structure-design/add_and_search_word_data_structure_design.go b/problems/add-and-search-word-data-structure-design/add_and_search_word_data_structure_design.go
deleted file mode 100644
index 763407809..000000000
--- a/problems/add-and-search-word-data-structure-design/add_and_search_word_data_structure_design.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem211
diff --git a/problems/add-and-search-word-data-structure-design/add_and_search_word_data_structure_design_test.go b/problems/add-and-search-word-data-structure-design/add_and_search_word_data_structure_design_test.go
deleted file mode 100644
index 763407809..000000000
--- a/problems/add-and-search-word-data-structure-design/add_and_search_word_data_structure_design_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem211
diff --git a/problems/add-binary/README.md b/problems/add-binary/README.md
deleted file mode 100644
index a8eaa0db1..000000000
--- a/problems/add-binary/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../plus-one "Plus One")
-　　　　　　　　　　　　　　　　
-[Next >](../text-justification "Text Justification")
-
-## [67. Add Binary (Easy)](https://leetcode.com/problems/add-binary "二进制求和")
-
-<p>Given two binary strings <code>a</code> and <code>b</code>, return <em>their sum as a binary string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> a = "11", b = "1"
-<strong>Output:</strong> "100"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> a = "1010", b = "1011"
-<strong>Output:</strong> "10101"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= a.length, b.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>a</code> and <code>b</code> consist&nbsp;only of <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code> characters.</li>
-	<li>Each string does not contain leading zeros except for the zero itself.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Add Two Numbers](../add-two-numbers) (Medium)
-  1. [Multiply Strings](../multiply-strings) (Medium)
-  1. [Plus One](../plus-one) (Easy)
-  1. [Add to Array-Form of Integer](../add-to-array-form-of-integer) (Easy)
diff --git a/problems/add-binary/add_binary.go b/problems/add-binary/add_binary.go
deleted file mode 100644
index 8acfc5b3c..000000000
--- a/problems/add-binary/add_binary.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem67
-
-func addBinary(a string, b string) string {
-	ans, l1, l2, carry := "", len(a)-1, len(b)-1, byte('0')
-	for l1 >= 0 || l2 >= 0 || carry != '0' {
-		v := carry
-		if l1 >= 0 {
-			v += a[l1] - '0'
-			l1--
-		}
-		if l2 >= 0 {
-			v += b[l2] - '0'
-			l2--
-		}
-		carry = '0' + (v-'0')/2
-		v = '0' + (v-'0')%2
-		ans = string(v) + ans
-	}
-	return ans
-}
diff --git a/problems/add-binary/add_binary_test.go b/problems/add-binary/add_binary_test.go
deleted file mode 100644
index d4dcd93f2..000000000
--- a/problems/add-binary/add_binary_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem67
-
-import "testing"
-
-type testType struct {
-	a    string
-	b    string
-	want string
-}
-
-func TestAddBinary(t *testing.T) {
-	tests := [...]testType{
-		{
-			a:    "11",
-			b:    "1",
-			want: "100",
-		},
-		{
-			a:    "1010",
-			b:    "1011",
-			want: "10101",
-		},
-		{
-			a:    "111",
-			b:    "111",
-			want: "1110",
-		},
-	}
-	for _, tt := range tests {
-		got := addBinary(tt.a, tt.b)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.a, tt.b, got, tt.want)
-		}
-	}
-}
diff --git a/problems/add-bold-tag-in-string/README.md b/problems/add-bold-tag-in-string/README.md
deleted file mode 100644
index 2af02380c..000000000
--- a/problems/add-bold-tag-in-string/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../average-salary-departments-vs-company "Average Salary: Departments VS Company")
-　　　　　　　　　　　　　　　　
-[Next >](../merge-two-binary-trees "Merge Two Binary Trees")
-
-## [616. Add Bold Tag in String (Medium)](https://leetcode.com/problems/add-bold-tag-in-string "给字符串添加加粗标签")
-
-Given a string <b>s</b> and a list of strings <b>dict</b>, you need to add a closed pair of bold tag <code>&lt;b&gt;</code> and <code>&lt;/b&gt;</code> to wrap the substrings in s that exist in dict. If two such substrings overlap, you need to wrap them together by only one pair of closed bold tag. Also, if two substrings wrapped by bold tags are consecutive, you need to combine them. 
-
-<p><b>Example 1:</b><br />
-<pre>
-<b>Input:</b> 
-s = "abcxyz123"
-dict = ["abc","123"]
-<b>Output:</b>
-"&lt;b&gt;abc&lt;/b&gt;xyz&lt;b&gt;123&lt;/b&gt;"
-</pre>
-</p>
-
-<p><b>Example 2:</b><br />
-<pre>
-<b>Input:</b> 
-s = "aaabbcc"
-dict = ["aaa","aab","bc"]
-<b>Output:</b>
-"&lt;b&gt;aaabbc&lt;/b&gt;c"
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>The given dict won't contain duplicates, and its length won't exceed 100.</li>
-<li>All the strings in input have length in range [1, 1000]. </li>
-</ol>
-</p>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Similar Questions
-  1. [Merge Intervals](../merge-intervals) (Medium)
-  1. [Tag Validator](../tag-validator) (Hard)
diff --git a/problems/add-bold-tag-in-string/add_bold_tag_in_string.go b/problems/add-bold-tag-in-string/add_bold_tag_in_string.go
deleted file mode 100644
index e8240e8a2..000000000
--- a/problems/add-bold-tag-in-string/add_bold_tag_in_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem616
diff --git a/problems/add-bold-tag-in-string/add_bold_tag_in_string_test.go b/problems/add-bold-tag-in-string/add_bold_tag_in_string_test.go
deleted file mode 100644
index e8240e8a2..000000000
--- a/problems/add-bold-tag-in-string/add_bold_tag_in_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem616
diff --git a/problems/add-digits/README.md b/problems/add-digits/README.md
deleted file mode 100644
index a691d58a8..000000000
--- a/problems/add-digits/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-paths "Binary Tree Paths")
-　　　　　　　　　　　　　　　　
-[Next >](../3sum-smaller "3Sum Smaller")
-
-## [258. Add Digits (Easy)](https://leetcode.com/problems/add-digits "各位相加")
-
-<p>Given an integer <code>num</code>, repeatedly add all its digits until the result has only one digit, and return it.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 38
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The process is
-38 --&gt; 3 + 8 --&gt; 11
-11 --&gt; 1 + 1 --&gt; 2 
-Since 2 has only one digit, return it.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= num &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you do it without any loop/recursion in <code>O(1)</code> runtime?</p>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-  [[Number Theory](../../tag/number-theory/README.md)]
-
-### Similar Questions
-  1. [Happy Number](../happy-number) (Easy)
-  1. [Sum of Digits in the Minimum Number](../sum-of-digits-in-the-minimum-number) (Easy)
-  1. [Sum of Digits of String After Convert](../sum-of-digits-of-string-after-convert) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A naive implementation of the above process is trivial. Could you come up with other methods?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What are all the possible results?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How do they occur, periodically or randomly?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-You may find this <a href="https://en.wikipedia.org/wiki/Digital_root" target="_blank">Wikipedia article</a> useful.
-</details>
diff --git a/problems/add-digits/add_digits.go b/problems/add-digits/add_digits.go
deleted file mode 100644
index e1673c7e8..000000000
--- a/problems/add-digits/add_digits.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem258
-
-func addDigits(num int) int {
-	return (num-1)%9 + 1
-}
diff --git a/problems/add-digits/add_digits_test.go b/problems/add-digits/add_digits_test.go
deleted file mode 100644
index 4272d203f..000000000
--- a/problems/add-digits/add_digits_test.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem258
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestAddDigits(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   38,
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := addDigits(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/add-minimum-number-of-rungs/README.md b/problems/add-minimum-number-of-rungs/README.md
deleted file mode 100644
index 75ced1a88..000000000
--- a/problems/add-minimum-number-of-rungs/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-words-you-can-type "Maximum Number of Words You Can Type")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-points-with-cost "Maximum Number of Points with Cost")
-
-## [1936. Add Minimum Number of Rungs (Medium)](https://leetcode.com/problems/add-minimum-number-of-rungs "新增的最少台阶数")
-
-<p>You are given a <strong>strictly increasing</strong> integer array <code>rungs</code> that represents the <strong>height</strong> of rungs on a ladder. You are currently on the <strong>floor</strong> at height <code>0</code>, and you want to reach the last rung.</p>
-
-<p>You are also given an integer <code>dist</code>. You can only climb to the next highest rung if the distance between where you are currently at (the floor or on a rung) and the next rung is <strong>at most</strong> <code>dist</code>. You are able to insert rungs at any positive <strong>integer</strong> height if a rung is not already there.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of rungs that must be added to the ladder in order for you to climb to the last rung.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rungs = [1,3,5,10], dist = 2
-<strong>Output:</strong> 2
-<strong>Explanation:
-</strong>You currently cannot reach the last rung.
-Add rungs at heights 7 and 8 to climb this ladder. 
-The ladder will now have rungs at [1,3,5,<u>7</u>,<u>8</u>,10].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rungs = [3,6,8,10], dist = 3
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-This ladder can be climbed without adding additional rungs.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> rungs = [3,4,6,7], dist = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-You currently cannot reach the first rung from the ground.
-Add a rung at height 1 to climb this ladder.
-The ladder will now have rungs at [<u>1</u>,3,4,6,7].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rungs.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= rungs[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= dist &lt;= 10<sup>9</sup></code></li>
-	<li><code>rungs</code> is <strong>strictly increasing</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Go as far as you can on the available rungs before adding new rungs.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you have to add a new rung, add it as high up as possible.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Try using division to decrease the number of computations.
-</details>
diff --git a/problems/add-one-row-to-tree/README.md b/problems/add-one-row-to-tree/README.md
deleted file mode 100644
index 46e4b2d6a..000000000
--- a/problems/add-one-row-to-tree/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-circular-queue "Design Circular Queue")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-distance-in-arrays "Maximum Distance in Arrays")
-
-## [623. Add One Row to Tree (Medium)](https://leetcode.com/problems/add-one-row-to-tree "在二叉树中增加一行")
-
-<p>Given the <code>root</code> of a binary tree and two integers <code>val</code> and <code>depth</code>, add a row of nodes with value <code>val</code> at the given depth <code>depth</code>.</p>
-
-<p>Note that the <code>root</code> node is at depth <code>1</code>.</p>
-
-<p>The adding rule is:</p>
-
-<ul>
-	<li>Given the integer <code>depth</code>, for each not null tree node <code>cur</code> at the depth <code>depth - 1</code>, create two tree nodes with value <code>val</code> as <code>cur</code>&#39;s left subtree root and right subtree root.</li>
-	<li><code>cur</code>&#39;s original left subtree should be the left subtree of the new left subtree root.</li>
-	<li><code>cur</code>&#39;s original right subtree should be the right subtree of the new right subtree root.</li>
-	<li>If <code>depth == 1</code> that means there is no depth <code>depth - 1</code> at all, then create a tree node with value <code>val</code> as the new root of the whole original tree, and the original tree is the new root&#39;s left subtree.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/15/addrow-tree.jpg" style="width: 500px; height: 231px;" />
-<pre>
-<strong>Input:</strong> root = [4,2,6,3,1,5], val = 1, depth = 2
-<strong>Output:</strong> [4,1,1,2,null,null,6,3,1,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/11/add2-tree.jpg" style="width: 500px; height: 277px;" />
-<pre>
-<strong>Input:</strong> root = [4,2,null,3,1], val = 1, depth = 3
-<strong>Output:</strong> [4,2,null,1,1,3,null,null,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li>The depth of the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-	<li><code>-10<sup>5</sup> &lt;= val &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= depth &lt;= the depth of tree + 1</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/add-one-row-to-tree/add_one_row_to_tree.go b/problems/add-one-row-to-tree/add_one_row_to_tree.go
deleted file mode 100644
index 332bbab67..000000000
--- a/problems/add-one-row-to-tree/add_one_row_to_tree.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package problem623
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func addOneRow(root *TreeNode, v int, d int) *TreeNode {
-	switch d {
-	case 1:
-		return &TreeNode{Val: v, Left: root}
-	case 2:
-		root.Left = &TreeNode{Val: v, Left: root.Left}
-		root.Right = &TreeNode{Val: v, Right: root.Right}
-	default:
-		if root.Left != nil {
-			root.Left = addOneRow(root.Left, v, d-1)
-		}
-		if root.Right != nil {
-			root.Right = addOneRow(root.Right, v, d-1)
-		}
-	}
-	return root
-}
diff --git a/problems/add-one-row-to-tree/add_one_row_to_tree_test.go b/problems/add-one-row-to-tree/add_one_row_to_tree_test.go
deleted file mode 100644
index ca8869b1f..000000000
--- a/problems/add-one-row-to-tree/add_one_row_to_tree_test.go
+++ /dev/null
@@ -1,52 +0,0 @@
-package problem623
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	v    int
-	d    int
-	want []int
-}
-
-func TestAddOneRow(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{4, 2, 6, 3, 1, 5},
-			v:    1,
-			d:    2,
-			want: []int{4, 1, 1, 2, kit.NULL, kit.NULL, 6, 3, 1, 5},
-		},
-		{
-			in:   []int{4, 2, kit.NULL, 3, 1},
-			v:    1,
-			d:    3,
-			want: []int{4, 2, kit.NULL, 1, 1, 3, kit.NULL, kit.NULL, 1},
-		},
-		{
-			in:   []int{3, 1},
-			v:    1,
-			d:    1,
-			want: []int{1, 3, kit.NULL, 1},
-		},
-		{
-			in:   []int{3, kit.NULL, 2},
-			v:    1,
-			d:    3,
-			want: []int{3, kit.NULL, 2, 1, 1},
-		},
-	}
-	for _, tt := range tests {
-		root := kit.SliceInt2TreeNode(tt.in)
-		root = addOneRow(root, tt.v, tt.d)
-		got := kit.TreeNode2SliceInt(root)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/add-strings/README.md b/problems/add-strings/README.md
deleted file mode 100644
index 165bbe5c5..000000000
--- a/problems/add-strings/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../third-maximum-number "Third Maximum Number")
-　　　　　　　　　　　　　　　　
-[Next >](../partition-equal-subset-sum "Partition Equal Subset Sum")
-
-## [415. Add Strings (Easy)](https://leetcode.com/problems/add-strings "字符串相加")
-
-<p>Given two non-negative integers, <code>num1</code> and <code>num2</code> represented as string, return <em>the sum of</em> <code>num1</code> <em>and</em> <code>num2</code> <em>as a string</em>.</p>
-
-<p>You must solve the problem without using any built-in library for handling large integers (such as <code>BigInteger</code>). You must also not convert the inputs to integers directly.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num1 = &quot;11&quot;, num2 = &quot;123&quot;
-<strong>Output:</strong> &quot;134&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num1 = &quot;456&quot;, num2 = &quot;77&quot;
-<strong>Output:</strong> &quot;533&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num1 = &quot;0&quot;, num2 = &quot;0&quot;
-<strong>Output:</strong> &quot;0&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num1.length, num2.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>num1</code> and <code>num2</code> consist of only digits.</li>
-	<li><code>num1</code> and <code>num2</code> don&#39;t have any leading zeros except for the zero itself.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Add Two Numbers](../add-two-numbers) (Medium)
-  1. [Multiply Strings](../multiply-strings) (Medium)
-  1. [Add to Array-Form of Integer](../add-to-array-form-of-integer) (Easy)
diff --git a/problems/add-strings/add_strings.go b/problems/add-strings/add_strings.go
deleted file mode 100644
index 3bf8c8173..000000000
--- a/problems/add-strings/add_strings.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem415
-
-func addStrings(num1 string, num2 string) string {
-	ans, l1, l2, carry := "", len(num1)-1, len(num2)-1, byte('0')
-	for l1 >= 0 || l2 >= 0 || carry != '0' {
-		v := carry
-		if l1 >= 0 {
-			v += num1[l1] - '0'
-			l1--
-		}
-		if l2 >= 0 {
-			v += num2[l2] - '0'
-			l2--
-		}
-		carry = '0' + (v-'0')/10
-		v = '0' + (v-'0')%10
-		ans = string(v) + ans
-	}
-	return ans
-}
diff --git a/problems/add-strings/add_strings_test.go b/problems/add-strings/add_strings_test.go
deleted file mode 100644
index 66ff5596e..000000000
--- a/problems/add-strings/add_strings_test.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package problem415
-
-import "testing"
-
-type testType struct {
-	num1 string
-	num2 string
-	want string
-}
-
-func TestAddStrings(t *testing.T) {
-	tests := [...]testType{
-		{
-			num1: "0",
-			num2: "0",
-			want: "0",
-		},
-		{
-			num1: "1",
-			num2: "2",
-			want: "3",
-		},
-		{
-			num1: "9",
-			num2: "9",
-			want: "18",
-		},
-		{
-			num1: "100",
-			num2: "999",
-			want: "1099",
-		},
-	}
-	for _, tt := range tests {
-		got := addStrings(tt.num1, tt.num2)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt, got, tt.want)
-		}
-	}
-}
diff --git a/problems/add-to-array-form-of-integer/README.md b/problems/add-to-array-form-of-integer/README.md
deleted file mode 100644
index 83da4ee23..000000000
--- a/problems/add-to-array-form-of-integer/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-string-starting-from-leaf "Smallest String Starting From Leaf")
-　　　　　　　　　　　　　　　　
-[Next >](../satisfiability-of-equality-equations "Satisfiability of Equality Equations")
-
-## [989. Add to Array-Form of Integer (Easy)](https://leetcode.com/problems/add-to-array-form-of-integer "数组形式的整数加法")
-
-<p>The <strong>array-form</strong> of an integer <code>num</code> is an array representing its digits in left to right order.</p>
-
-<ul>
-	<li>For example, for <code>num = 1321</code>, the array form is <code>[1,3,2,1]</code>.</li>
-</ul>
-
-<p>Given <code>num</code>, the <strong>array-form</strong> of an integer, and an integer <code>k</code>, return <em>the <strong>array-form</strong> of the integer</em> <code>num + k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = [1,2,0,0], k = 34
-<strong>Output:</strong> [1,2,3,4]
-<strong>Explanation:</strong> 1200 + 34 = 1234
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = [2,7,4], k = 181
-<strong>Output:</strong> [4,5,5]
-<strong>Explanation:</strong> 274 + 181 = 455
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = [2,1,5], k = 806
-<strong>Output:</strong> [1,0,2,1]
-<strong>Explanation:</strong> 215 + 806 = 1021
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = [9,9,9,9,9,9,9,9,9,9], k = 1
-<strong>Output:</strong> [1,0,0,0,0,0,0,0,0,0,0]
-<strong>Explanation:</strong> 9999999999 + 1 = 10000000000
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= num[i] &lt;= 9</code></li>
-	<li><code>num</code>&nbsp;does not contain any leading zeros except for the zero itself.</li>
-	<li><code>1 &lt;= k &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Add Two Numbers](../add-two-numbers) (Medium)
-  1. [Plus One](../plus-one) (Easy)
-  1. [Add Binary](../add-binary) (Easy)
-  1. [Add Strings](../add-strings) (Easy)
diff --git a/problems/add-to-array-form-of-integer/add_to_array_form_of_integer.go b/problems/add-to-array-form-of-integer/add_to_array_form_of_integer.go
deleted file mode 100644
index 6223942e9..000000000
--- a/problems/add-to-array-form-of-integer/add_to_array_form_of_integer.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem989
-
-func addToArrayForm(A []int, K int) []int {
-	ans, carry, l := make([]int, 0), 0, len(A)-1
-	for carry > 0 || K > 0 || l >= 0 {
-		x := K%10 + carry
-		if l >= 0 {
-			x, l = x+A[l], l-1
-		}
-		carry, K = x/10, K/10
-		ans = append([]int{x % 10}, ans...)
-	}
-	return ans
-}
diff --git a/problems/add-to-array-form-of-integer/add_to_array_form_of_integer_test.go b/problems/add-to-array-form-of-integer/add_to_array_form_of_integer_test.go
deleted file mode 100644
index bba949e63..000000000
--- a/problems/add-to-array-form-of-integer/add_to_array_form_of_integer_test.go
+++ /dev/null
@@ -1,38 +0,0 @@
-package problem989
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	k    int
-	want []int
-}
-
-func TestAddToArrayForm(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 0, 0},
-			k:    34,
-			want: []int{1, 2, 3, 4},
-		},
-		{
-			in:   []int{2, 1, 5},
-			k:    806,
-			want: []int{1, 0, 2, 1},
-		},
-		{
-			in:   []int{9, 9, 9, 9, 9, 9, 9, 9, 9, 9},
-			k:    1,
-			want: []int{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
-		},
-	}
-	for _, tt := range tests {
-		got := addToArrayForm(tt.in, tt.k)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/add-two-numbers-ii/README.md b/problems/add-two-numbers-ii/README.md
deleted file mode 100644
index 8a1ffe7ee..000000000
--- a/problems/add-two-numbers-ii/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sequence-reconstruction "Sequence Reconstruction")
-　　　　　　　　　　　　　　　　
-[Next >](../arithmetic-slices-ii-subsequence "Arithmetic Slices II - Subsequence")
-
-## [445. Add Two Numbers II (Medium)](https://leetcode.com/problems/add-two-numbers-ii "两数相加 II")
-
-<p>You are given two <strong>non-empty</strong> linked lists representing two non-negative integers. The most significant digit comes first and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.</p>
-
-<p>You may assume the two numbers do not contain any leading zero, except the number 0 itself.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/09/sumii-linked-list.jpg" style="width: 523px; height: 342px;" />
-<pre>
-<strong>Input:</strong> l1 = [7,2,4,3], l2 = [5,6,4]
-<strong>Output:</strong> [7,8,0,7]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> l1 = [2,4,3], l2 = [5,6,4]
-<strong>Output:</strong> [8,0,7]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> l1 = [0], l2 = [0]
-<strong>Output:</strong> [0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in each linked list is in the range <code>[1, 100]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 9</code></li>
-	<li>It is guaranteed that the list represents a number that does not have leading zeros.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong>&nbsp;Could you solve it without reversing the input lists?</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Add Two Numbers](../add-two-numbers) (Medium)
diff --git a/problems/add-two-numbers-ii/add_two_numbers_ii.go b/problems/add-two-numbers-ii/add_two_numbers_ii.go
deleted file mode 100644
index e6c4cae64..000000000
--- a/problems/add-two-numbers-ii/add_two_numbers_ii.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package problem445
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
-	s1, s2 := make([]int, 0), make([]int, 0)
-	for l1 != nil {
-		s1 = append(s1, l1.Val)
-		l1 = l1.Next
-	}
-	for l2 != nil {
-		s2 = append(s2, l2.Val)
-		l2 = l2.Next
-	}
-	ans, n1, n2, carry := &ListNode{}, len(s1)-1, len(s2)-1, 0
-	for n1 >= 0 || n2 >= 0 || carry > 0 {
-		if n1 >= 0 {
-			carry += s1[n1]
-			n1--
-		}
-		if n2 >= 0 {
-			carry += s2[n2]
-			n2--
-		}
-		ans.Val = carry % 10
-		ans = &ListNode{Val: 0, Next: ans}
-		carry /= 10
-	}
-	return ans.Next
-}
diff --git a/problems/add-two-numbers-ii/add_two_numbers_ii_test.go b/problems/add-two-numbers-ii/add_two_numbers_ii_test.go
deleted file mode 100644
index 3d09f2cda..000000000
--- a/problems/add-two-numbers-ii/add_two_numbers_ii_test.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package problem445
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	l1   []int
-	l2   []int
-	want []int
-}
-
-func TestAddTwoNumbers(t *testing.T) {
-	tests := [...]testType{
-		{
-			l1:   []int{7, 2, 4, 3},
-			l2:   []int{5, 6, 4},
-			want: []int{7, 8, 0, 7},
-		},
-		{
-			l1:   []int{2, 4, 3},
-			l2:   []int{5, 6, 4},
-			want: []int{8, 0, 7},
-		},
-		{
-			l1:   []int{5},
-			l2:   []int{5},
-			want: []int{1, 0},
-		},
-		{
-			l1:   []int{5},
-			l2:   []int{5, 9, 9},
-			want: []int{6, 0, 4},
-		},
-	}
-	for _, tt := range tests {
-		l1 := kit.SliceInt2ListNode(tt.l1)
-		l2 := kit.SliceInt2ListNode(tt.l2)
-		got := kit.ListNode2SliceInt(addTwoNumbers(l1, l2))
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.l1, tt.l2, got, tt.want)
-		}
-	}
-}
diff --git a/problems/add-two-numbers/README.md b/problems/add-two-numbers/README.md
deleted file mode 100644
index 4b8b6c228..000000000
--- a/problems/add-two-numbers/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-sum "Two Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-substring-without-repeating-characters "Longest Substring Without Repeating Characters")
-
-## [2. Add Two Numbers (Medium)](https://leetcode.com/problems/add-two-numbers "两数相加")
-
-<p>You are given two <strong>non-empty</strong> linked lists representing two non-negative integers. The digits are stored in <strong>reverse order</strong>, and each of their nodes contains a single digit. Add the two numbers and return the sum&nbsp;as a linked list.</p>
-
-<p>You may assume the two numbers do not contain any leading zero, except the number 0 itself.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/02/addtwonumber1.jpg" style="width: 483px; height: 342px;" />
-<pre>
-<strong>Input:</strong> l1 = [2,4,3], l2 = [5,6,4]
-<strong>Output:</strong> [7,0,8]
-<strong>Explanation:</strong> 342 + 465 = 807.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> l1 = [0], l2 = [0]
-<strong>Output:</strong> [0]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
-<strong>Output:</strong> [8,9,9,9,0,0,0,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in each linked list is in the range <code>[1, 100]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 9</code></li>
-	<li>It is guaranteed that the list represents a number that does not have leading zeros.</li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Multiply Strings](../multiply-strings) (Medium)
-  1. [Add Binary](../add-binary) (Easy)
-  1. [Sum of Two Integers](../sum-of-two-integers) (Medium)
-  1. [Add Strings](../add-strings) (Easy)
-  1. [Add Two Numbers II](../add-two-numbers-ii) (Medium)
-  1. [Add to Array-Form of Integer](../add-to-array-form-of-integer) (Easy)
diff --git a/problems/add-two-numbers/add_two_numbers.go b/problems/add-two-numbers/add_two_numbers.go
deleted file mode 100644
index 2bd03f25e..000000000
--- a/problems/add-two-numbers/add_two_numbers.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package problem2
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
-	ans, carry := &ListNode{}, 0
-	t := ans
-	for l1 != nil || l2 != nil || carry != 0 {
-		if l1 != nil {
-			carry += l1.Val
-			l1 = l1.Next
-		}
-		if l2 != nil {
-			carry += l2.Val
-			l2 = l2.Next
-		}
-		t.Next = &ListNode{Val: carry % 10}
-		t = t.Next
-		carry /= 10
-	}
-	return ans.Next
-}
diff --git a/problems/add-two-numbers/add_two_numbers_test.go b/problems/add-two-numbers/add_two_numbers_test.go
deleted file mode 100644
index 435a43070..000000000
--- a/problems/add-two-numbers/add_two_numbers_test.go
+++ /dev/null
@@ -1,42 +0,0 @@
-package problem2
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	l1   []int
-	l2   []int
-	want []int
-}
-
-func TestAddTwoNumbers(t *testing.T) {
-	tests := [...]testType{
-		{
-			l1:   []int{2, 4, 3},
-			l2:   []int{5, 6, 4},
-			want: []int{7, 0, 8},
-		},
-		{
-			l1:   []int{5},
-			l2:   []int{5},
-			want: []int{0, 1},
-		},
-		{
-			l1:   []int{5},
-			l2:   []int{5, 9, 9},
-			want: []int{0, 0, 0, 1},
-		},
-	}
-	for _, tt := range tests {
-		l1 := kit.SliceInt2ListNode(tt.l1)
-		l2 := kit.SliceInt2ListNode(tt.l2)
-		got := kit.ListNode2SliceInt(addTwoNumbers(l1, l2))
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.l1, tt.l2, got, tt.want)
-		}
-	}
-}
diff --git a/problems/add-two-polynomials-represented-as-linked-lists/README.md b/problems/add-two-polynomials-represented-as-linked-lists/README.md
deleted file mode 100644
index 3c0db5e11..000000000
--- a/problems/add-two-polynomials-represented-as-linked-lists/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../percentage-of-users-attended-a-contest "Percentage of Users Attended a Contest")
-　　　　　　　　　　　　　　　　
-[Next >](../hopper-company-queries-i "Hopper Company Queries I")
-
-## [1634. Add Two Polynomials Represented as Linked Lists (Medium)](https://leetcode.com/problems/add-two-polynomials-represented-as-linked-lists "求两个多项式链表的和")
-
-
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Process both linked lists at the same time
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the current power of the two heads is equal, add this power with the sum of the coefficients to the answer list.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If one head has a larger power, add this power to the answer list and move only this head.
-</details>
diff --git a/problems/adding-spaces-to-a-string/README.md b/problems/adding-spaces-to-a-string/README.md
deleted file mode 100644
index 2239ba4fd..000000000
--- a/problems/adding-spaces-to-a-string/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-first-palindromic-string-in-the-array "Find First Palindromic String in the Array")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-smooth-descent-periods-of-a-stock "Number of Smooth Descent Periods of a Stock")
-
-## [2109. Adding Spaces to a String (Medium)](https://leetcode.com/problems/adding-spaces-to-a-string "向字符串添加空格")
-
-<p>You are given a <strong>0-indexed</strong> string <code>s</code> and a <strong>0-indexed</strong> integer array <code>spaces</code> that describes the indices in the original string where spaces will be added. Each space should be inserted <strong>before</strong> the character at the given index.</p>
-
-<ul>
-	<li>For example, given <code>s = &quot;EnjoyYourCoffee&quot;</code> and <code>spaces = [5, 9]</code>, we place spaces before <code>&#39;Y&#39;</code> and <code>&#39;C&#39;</code>, which are at indices <code>5</code> and <code>9</code> respectively. Thus, we obtain <code>&quot;Enjoy <strong><u>Y</u></strong>our <u><strong>C</strong></u>offee&quot;</code>.</li>
-</ul>
-
-<p>Return<strong> </strong><em>the modified string <strong>after</strong> the spaces have been added.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;LeetcodeHelpsMeLearn&quot;, spaces = [8,13,15]
-<strong>Output:</strong> &quot;Leetcode Helps Me Learn&quot;
-<strong>Explanation:</strong> 
-The indices 8, 13, and 15 correspond to the underlined characters in &quot;Leetcode<u><strong>H</strong></u>elps<u><strong>M</strong></u>e<u><strong>L</strong></u>earn&quot;.
-We then place spaces before those characters.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;icodeinpython&quot;, spaces = [1,5,7,9]
-<strong>Output:</strong> &quot;i code in py thon&quot;
-<strong>Explanation:</strong>
-The indices 1, 5, 7, and 9 correspond to the underlined characters in &quot;i<u><strong>c</strong></u>ode<u><strong>i</strong></u>n<u><strong>p</strong></u>y<u><strong>t</strong></u>hon&quot;.
-We then place spaces before those characters.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;spacing&quot;, spaces = [0,1,2,3,4,5,6]
-<strong>Output:</strong> &quot; s p a c i n g&quot;
-<strong>Explanation:</strong>
-We are also able to place spaces before the first character of the string.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 3 * 10<sup>5</sup></code></li>
-	<li><code>s</code> consists only of lowercase and uppercase English letters.</li>
-	<li><code>1 &lt;= spaces.length &lt;= 3 * 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= spaces[i] &lt;= s.length - 1</code></li>
-	<li>All the values of <code>spaces</code> are <strong>strictly increasing</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create a new string, initially empty, as the modified string. Iterate through the original string and append each character of the original string to the new string. However, each time you reach a character that requires a space before it, append a space before appending the character.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Since the array of indices for the space locations is sorted, use a pointer to keep track of the next index to place a space. Only increment the pointer once a space has been appended.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Ensure that your append operation can be done in O(1).
-</details>
diff --git a/problems/adding-two-negabinary-numbers/README.md b/problems/adding-two-negabinary-numbers/README.md
deleted file mode 100644
index be61ff03b..000000000
--- a/problems/adding-two-negabinary-numbers/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flip-columns-for-maximum-number-of-equal-rows "Flip Columns For Maximum Number of Equal Rows")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-submatrices-that-sum-to-target "Number of Submatrices That Sum to Target")
-
-## [1073. Adding Two Negabinary Numbers (Medium)](https://leetcode.com/problems/adding-two-negabinary-numbers "负二进制数相加")
-
-<p>Given two numbers <code>arr1</code> and <code>arr2</code> in base <strong>-2</strong>, return the result of adding them together.</p>
-
-<p>Each number is given in <em>array format</em>:&nbsp; as an array of 0s and 1s, from most significant bit to least significant bit.&nbsp; For example, <code>arr = [1,1,0,1]</code> represents the number <code>(-2)^3&nbsp;+ (-2)^2 + (-2)^0 = -3</code>.&nbsp; A number <code>arr</code> in <em>array, format</em> is also guaranteed to have no leading zeros: either&nbsp;<code>arr == [0]</code> or <code>arr[0] == 1</code>.</p>
-
-<p>Return the result of adding <code>arr1</code> and <code>arr2</code> in the same format: as an array of 0s and 1s with no leading zeros.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [1,1,1,1,1], arr2 = [1,0,1]
-<strong>Output:</strong> [1,0,0,0,0]
-<strong>Explanation: </strong>arr1 represents 11, arr2 represents 5, the output represents 16.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [0], arr2 = [0]
-<strong>Output:</strong> [0]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [0], arr2 = [1]
-<strong>Output:</strong> [1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr1.length,&nbsp;arr2.length &lt;= 1000</code></li>
-	<li><code>arr1[i]</code>&nbsp;and <code>arr2[i]</code> are&nbsp;<code>0</code> or <code>1</code></li>
-	<li><code>arr1</code> and <code>arr2</code> have no leading zeros</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can try to determine the last digit of the answer, then divide everything by 2 and repeat.
-</details>
diff --git a/problems/adding-two-negabinary-numbers/adding_two_negabinary_numbers.go b/problems/adding-two-negabinary-numbers/adding_two_negabinary_numbers.go
deleted file mode 100644
index de035c93e..000000000
--- a/problems/adding-two-negabinary-numbers/adding_two_negabinary_numbers.go
+++ /dev/null
@@ -1,38 +0,0 @@
-package problem1073
-
-func addNegabinary(A, B []int) []int {
-	i, j := len(A)-1, len(B)-1
-	res := make([]int, 0, i+j)
-	carry := 0
-	for i >= 0 || j >= 0 || carry != 0 {
-		if i >= 0 {
-			carry += A[i]
-			i--
-		}
-		if j >= 0 {
-			carry += B[j]
-			j--
-		}
-		res = append(res, carry&1)
-		carry = -(carry >> 1)
-	}
-
-	res = reverse(res)
-
-	// cut leading zero
-	i, end := 0, len(res)-1
-	for i < end && res[i] == 0 {
-		i++
-	}
-	return res[i:]
-}
-
-func reverse(A []int) []int {
-	i, j := 0, len(A)-1
-	for i < j {
-		A[i], A[j] = A[j], A[i]
-		i++
-		j--
-	}
-	return A
-}
diff --git a/problems/additive-number/README.md b/problems/additive-number/README.md
deleted file mode 100644
index dc51c75c0..000000000
--- a/problems/additive-number/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-islands-ii "Number of Islands II")
-　　　　　　　　　　　　　　　　
-[Next >](../range-sum-query-mutable "Range Sum Query - Mutable")
-
-## [306. Additive Number (Medium)](https://leetcode.com/problems/additive-number "累加数")
-
-<p>Additive number is a string whose digits can form additive sequence.</p>
-
-<p>A valid additive sequence should contain <b>at least</b> three numbers. Except for the first two numbers, each subsequent number in the sequence must be the sum of the preceding two.</p>
-
-<p>Given a string containing only digits <code>&#39;0&#39;-&#39;9&#39;</code>, write a function to determine if it&#39;s an additive number.</p>
-
-<p><b>Note:</b> Numbers in the additive sequence <b>cannot</b> have leading zeros, so sequence <code>1, 2, 03</code> or <code>1, 02, 3</code> is invalid.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> &quot;112358&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The digits can form an additive sequence: 1, 1, 2, 3, 5, 8. 
-&nbsp;            1 + 1 = 2, 1 + 2 = 3, 2 + 3 = 5, 3 + 5 = 8
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> &quot;199100199&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The additive sequence is: 1, 99, 100, 199.&nbsp;
-&nbsp;            1 + 99 = 100, 99 + 100 = 199
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><font face="monospace"><code>num</code>&nbsp;</font>consists only of digits <code>&#39;0&#39;-&#39;9&#39;</code>.</li>
-	<li><code>1 &lt;= num.length &lt;= 35</code></li>
-</ul>
-
-<p><b>Follow up:</b><br />
-How would you handle overflow for very large input integers?</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Split Array into Fibonacci Sequence](../split-array-into-fibonacci-sequence) (Medium)
diff --git a/problems/additive-number/additive_number.go b/problems/additive-number/additive_number.go
deleted file mode 100644
index 365e31f15..000000000
--- a/problems/additive-number/additive_number.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem306
diff --git a/problems/additive-number/additive_number_test.go b/problems/additive-number/additive_number_test.go
deleted file mode 100644
index 365e31f15..000000000
--- a/problems/additive-number/additive_number_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem306
diff --git a/problems/ads-performance/README.md b/problems/ads-performance/README.md
deleted file mode 100644
index 6ab077012..000000000
--- a/problems/ads-performance/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../restaurant-growth "Restaurant Growth")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-69-number "Maximum 69 Number")
-
-## [1322. Ads Performance (Easy)](https://leetcode.com/problems/ads-performance "广告效果")
-
-<p>Table: <code>Ads</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| ad_id         | int     |
-| user_id       | int     |
-| action        | enum    |
-+---------------+---------+
-(ad_id, user_id) is the primary key for this table.
-Each row of this table contains the ID of an Ad, the ID of a user and the action taken by this user regarding this Ad.
-The action column is an ENUM type of ('Clicked', 'Viewed', 'Ignored').
-</pre>
- 
-A company is running Ads and wants to calculate the performance of each Ad.
-
-Performance of the Ad is measured using Click-Through Rate (CTR) where:
-
-[[image-blog:Leetcode: Ads Performance][https://raw.githubusercontent.com/dennyzhang/code.dennyzhang.com/master/problems/ads-performance/ctrformula.png]]
-
-Write an SQL query to find the ctr of each Ad.
-
-Round ctr to 2 decimal points. Order the result table by ctr in descending order and by ad_id in ascending order in case of a tie.
-
-The query result format is in the following example:
-<pre>
-Ads table:
-+-------+---------+---------+
-| ad_id | user_id | action  |
-+-------+---------+---------+
-| 1     | 1       | Clicked |
-| 2     | 2       | Clicked |
-| 3     | 3       | Viewed  |
-| 5     | 5       | Ignored |
-| 1     | 7       | Ignored |
-| 2     | 7       | Viewed  |
-| 3     | 5       | Clicked |
-| 1     | 4       | Viewed  |
-| 2     | 11      | Viewed  |
-| 1     | 2       | Clicked |
-+-------+---------+---------+
-Result table:
-+-------+-------+
-| ad_id | ctr   |
-+-------+-------+
-| 1     | 66.67 |
-| 3     | 50.00 |
-| 2     | 33.33 |
-| 5     | 0.00  |
-+-------+-------+
-for ad_id = 1, ctr = (2/(2+1)) * 100 = 66.67
-for ad_id = 2, ctr = (1/(1+2)) * 100 = 33.33
-for ad_id = 3, ctr = (1/(1+1)) * 100 = 50.00
-for ad_id = 5, ctr = 0.00, Note that ad_id has no clicks or views.
-Note that we don't care about Ignored Ads.
-Result table is ordered by the ctr. in case of a tie we order them by ad_id
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/ads-performance/mysql_schemas.sql b/problems/ads-performance/mysql_schemas.sql
deleted file mode 100644
index 0ccce8bb5..000000000
--- a/problems/ads-performance/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Ads (ad_id int, user_id int, action ENUM('Clicked', 'Viewed', 'Ignored'));
-Truncate table Ads;
-insert into Ads (ad_id, user_id, action) values ('1', '1', 'Clicked');
-insert into Ads (ad_id, user_id, action) values ('2', '2', 'Clicked');
-insert into Ads (ad_id, user_id, action) values ('3', '3', 'Viewed');
-insert into Ads (ad_id, user_id, action) values ('5', '5', 'Ignored');
-insert into Ads (ad_id, user_id, action) values ('1', '7', 'Ignored');
-insert into Ads (ad_id, user_id, action) values ('2', '7', 'Viewed');
-insert into Ads (ad_id, user_id, action) values ('3', '5', 'Clicked');
-insert into Ads (ad_id, user_id, action) values ('1', '4', 'Viewed');
-insert into Ads (ad_id, user_id, action) values ('2', '11', 'Viewed');
-insert into Ads (ad_id, user_id, action) values ('1', '2', 'Clicked');
diff --git a/problems/advantage-shuffle/README.md b/problems/advantage-shuffle/README.md
deleted file mode 100644
index 129cfef84..000000000
--- a/problems/advantage-shuffle/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reordered-power-of-2 "Reordered Power of 2")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-refueling-stops "Minimum Number of Refueling Stops")
-
-## [870. Advantage Shuffle (Medium)](https://leetcode.com/problems/advantage-shuffle "优势洗牌")
-
-<p>You are given two integer arrays <code>nums1</code> and <code>nums2</code> both of the same length. The <strong>advantage</strong> of <code>nums1</code> with respect to <code>nums2</code> is the number of indices <code>i</code> for which <code>nums1[i] &gt; nums2[i]</code>.</p>
-
-<p>Return <em>any permutation of </em><code>nums1</code><em> that maximizes its <strong>advantage</strong> with respect to </em><code>nums2</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums1 = [2,7,11,15], nums2 = [1,10,4,11]
-<strong>Output:</strong> [2,11,7,15]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums1 = [12,24,8,32], nums2 = [13,25,32,11]
-<strong>Output:</strong> [24,32,8,12]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums2.length == nums1.length</code></li>
-	<li><code>0 &lt;= nums1[i], nums2[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/advantage-shuffle/advantage_shuffle.go b/problems/advantage-shuffle/advantage_shuffle.go
deleted file mode 100644
index 95db8416b..000000000
--- a/problems/advantage-shuffle/advantage_shuffle.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem870
diff --git a/problems/advantage-shuffle/advantage_shuffle_test.go b/problems/advantage-shuffle/advantage_shuffle_test.go
deleted file mode 100644
index 95db8416b..000000000
--- a/problems/advantage-shuffle/advantage_shuffle_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem870
diff --git a/problems/airplane-seat-assignment-probability/README.md b/problems/airplane-seat-assignment-probability/README.md
deleted file mode 100644
index 27e58d0cf..000000000
--- a/problems/airplane-seat-assignment-probability/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-dining-philosophers "The Dining Philosophers")
-　　　　　　　　　　　　　　　　
-[Next >](../missing-number-in-arithmetic-progression "Missing Number In Arithmetic Progression")
-
-## [1227. Airplane Seat Assignment Probability (Medium)](https://leetcode.com/problems/airplane-seat-assignment-probability "飞机座位分配概率")
-
-<p><code data-stringify-type="code">n</code>&nbsp;passengers board an airplane with exactly&nbsp;<code data-stringify-type="code">n</code>&nbsp;seats. The first passenger has lost the ticket and picks a seat randomly. But after that, the rest of passengers will:</p>
-
-<ul>
-	<li>Take their own seat if it is still available,&nbsp;</li>
-	<li>Pick other seats randomly when they find their seat occupied&nbsp;</li>
-</ul>
-
-<p>What is the probability that the n-th person can get his own seat?</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1.00000
-<strong>Explanation: </strong>The first person can only get the first seat.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 0.50000
-<strong>Explanation: </strong>The second person has a probability of 0.5 to get the second seat (when first person gets the first seat).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10^5</code></li>
-</ul>
-
-### Related Topics
-  [[Brainteaser](../../tag/brainteaser/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Probability and Statistics](../../tag/probability-and-statistics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming, dp[i] indicates the probability that the i-th person can get his seat when there're i persons in total. It's okay to start with O(n^2) solution and then optimize it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to find the regular pattern of the result.
-</details>
diff --git a/problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period/README.md b/problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period/README.md
deleted file mode 100644
index a91e1b097..000000000
--- a/problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-parking-system "Design Parking System")
-　　　　　　　　　　　　　　　　
-[Next >](../find-valid-matrix-given-row-and-column-sums "Find Valid Matrix Given Row and Column Sums")
-
-## [1604. Alert Using Same Key-Card Three or More Times in a One Hour Period (Medium)](https://leetcode.com/problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period "警告一小时内使用相同员工卡大于等于三次的人")
-
-<p>LeetCode company workers use key-cards to unlock office doors. Each time a worker uses their key-card, the security system saves the worker&#39;s name and the time when it was used. The system emits an <strong>alert</strong> if any worker uses the key-card <strong>three or more times</strong> in a one-hour period.</p>
-
-<p>You are given a list of strings <code>keyName</code> and <code>keyTime</code> where <code>[keyName[i], keyTime[i]]</code> corresponds to a person&#39;s name and the time when their key-card was used <strong>in a</strong> <strong>single day</strong>.</p>
-
-<p>Access times are given in the <strong>24-hour time format &quot;HH:MM&quot;</strong>, such as <code>&quot;23:51&quot;</code> and <code>&quot;09:49&quot;</code>.</p>
-
-<p>Return a <em>list of unique worker names who received an alert for frequent keycard use</em>. Sort the names in <strong>ascending order alphabetically</strong>.</p>
-
-<p>Notice that <code>&quot;10:00&quot;</code> - <code>&quot;11:00&quot;</code> is considered to be within a one-hour period, while <code>&quot;22:51&quot;</code> - <code>&quot;23:52&quot;</code> is not considered to be within a one-hour period.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> keyName = [&quot;daniel&quot;,&quot;daniel&quot;,&quot;daniel&quot;,&quot;luis&quot;,&quot;luis&quot;,&quot;luis&quot;,&quot;luis&quot;], keyTime = [&quot;10:00&quot;,&quot;10:40&quot;,&quot;11:00&quot;,&quot;09:00&quot;,&quot;11:00&quot;,&quot;13:00&quot;,&quot;15:00&quot;]
-<strong>Output:</strong> [&quot;daniel&quot;]
-<strong>Explanation:</strong> &quot;daniel&quot; used the keycard 3 times in a one-hour period (&quot;10:00&quot;,&quot;10:40&quot;, &quot;11:00&quot;).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> keyName = [&quot;alice&quot;,&quot;alice&quot;,&quot;alice&quot;,&quot;bob&quot;,&quot;bob&quot;,&quot;bob&quot;,&quot;bob&quot;], keyTime = [&quot;12:01&quot;,&quot;12:00&quot;,&quot;18:00&quot;,&quot;21:00&quot;,&quot;21:20&quot;,&quot;21:30&quot;,&quot;23:00&quot;]
-<strong>Output:</strong> [&quot;bob&quot;]
-<strong>Explanation:</strong> &quot;bob&quot; used the keycard 3 times in a one-hour period (&quot;21:00&quot;,&quot;21:20&quot;, &quot;21:30&quot;).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= keyName.length, keyTime.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>keyName.length == keyTime.length</code></li>
-	<li><code>keyTime[i]</code> is in the format <strong>&quot;HH:MM&quot;</strong>.</li>
-	<li><code>[keyName[i], keyTime[i]]</code> is <strong>unique</strong>.</li>
-	<li><code>1 &lt;= keyName[i].length &lt;= 10</code></li>
-	<li><code>keyName[i] contains only lowercase English letters.</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Group the times by the name of the card user, then sort each group
-</details>
diff --git a/problems/alien-dictionary/README.md b/problems/alien-dictionary/README.md
deleted file mode 100644
index 4c7fde95a..000000000
--- a/problems/alien-dictionary/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../missing-number "Missing Number")
-　　　　　　　　　　　　　　　　
-[Next >](../closest-binary-search-tree-value "Closest Binary Search Tree Value")
-
-## [269. Alien Dictionary (Hard)](https://leetcode.com/problems/alien-dictionary "火星词典")
-
-<p>There is a new alien language which uses the latin alphabet. However, the order among letters are unknown to you. You receive a list of <b>non-empty</b> words from the dictionary, where <b>words are sorted lexicographically by the rules of this new language</b>. Derive the order of letters in this language.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<strong>Input:</strong>
-[
-  &quot;wrt&quot;,
-  &quot;wrf&quot;,
-  &quot;er&quot;,
-  &quot;ett&quot;,
-  &quot;rftt&quot;
-]
-
-<strong>Output: </strong><code>&quot;wertf&quot;</code>
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<strong>Input:</strong>
-[
-  &quot;z&quot;,
-  &quot;x&quot;
-]
-
-<strong>Output: </strong><code>&quot;zx&quot;</code>
-</pre>
-
-<p><b>Example 3:</b></p>
-
-<pre>
-<strong>Input:</strong>
-[
-  &quot;z&quot;,
-  &quot;x&quot;,
-  &quot;z&quot;
-] 
-
-<strong>Output:</strong> <code>&quot;&quot;</code>&nbsp;
-
-<strong>Explanation:</strong> The order is invalid, so return <code>&quot;&quot;</code>.
-</pre>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>You may assume all letters are in lowercase.</li>
-	<li>You may assume that if a is a prefix of b, then a must appear before b in the given dictionary.</li>
-	<li>If the order is invalid, return an empty string.</li>
-	<li>There may be multiple valid order of letters, return any one of them is fine.</li>
-</ol>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Course Schedule II](../course-schedule-ii) (Medium)
diff --git a/problems/alien-dictionary/alien_dictionary.go b/problems/alien-dictionary/alien_dictionary.go
deleted file mode 100644
index e2e505be7..000000000
--- a/problems/alien-dictionary/alien_dictionary.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem269
diff --git a/problems/alien-dictionary/alien_dictionary_test.go b/problems/alien-dictionary/alien_dictionary_test.go
deleted file mode 100644
index e2e505be7..000000000
--- a/problems/alien-dictionary/alien_dictionary_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem269
diff --git a/problems/all-divisions-with-the-highest-score-of-a-binary-array/README.md b/problems/all-divisions-with-the-highest-score-of-a-binary-array/README.md
deleted file mode 100644
index 3e8ea2eca..000000000
--- a/problems/all-divisions-with-the-highest-score-of-a-binary-array/README.md
+++ /dev/null
@@ -1,92 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../keep-multiplying-found-values-by-two "Keep Multiplying Found Values by Two")
-　　　　　　　　　　　　　　　　
-[Next >](../find-substring-with-given-hash-value "Find Substring With Given Hash Value")
-
-## [2155. All Divisions With the Highest Score of a Binary Array (Medium)](https://leetcode.com/problems/all-divisions-with-the-highest-score-of-a-binary-array "分组得分最高的所有下标")
-
-<p>You are given a <strong>0-indexed</strong> binary array <code>nums</code> of length <code>n</code>. <code>nums</code> can be divided at index <code>i</code> (where <code>0 &lt;= i &lt;= n)</code> into two arrays (possibly empty) <code>nums<sub>left</sub></code> and <code>nums<sub>right</sub></code>:</p>
-
-<ul>
-	<li><code>nums<sub>left</sub></code> has all the elements of <code>nums</code> between index <code>0</code> and <code>i - 1</code> <strong>(inclusive)</strong>, while <code>nums<sub>right</sub></code> has all the elements of nums between index <code>i</code> and <code>n - 1</code> <strong>(inclusive)</strong>.</li>
-	<li>If <code>i == 0</code>, <code>nums<sub>left</sub></code> is <strong>empty</strong>, while <code>nums<sub>right</sub></code> has all the elements of <code>nums</code>.</li>
-	<li>If <code>i == n</code>, <code>nums<sub>left</sub></code> has all the elements of nums, while <code>nums<sub>right</sub></code> is <strong>empty</strong>.</li>
-</ul>
-
-<p>The <strong>division score</strong> of an index <code>i</code> is the <strong>sum</strong> of the number of <code>0</code>&#39;s in <code>nums<sub>left</sub></code> and the number of <code>1</code>&#39;s in <code>nums<sub>right</sub></code>.</p>
-
-<p>Return <em><strong>all distinct indices</strong> that have the <strong>highest</strong> possible <strong>division score</strong></em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,1,0]
-<strong>Output:</strong> [2,4]
-<strong>Explanation:</strong> Division at index
-- 0: nums<sub>left</sub> is []. nums<sub>right</sub> is [0,0,<u><strong>1</strong></u>,0]. The score is 0 + 1 = 1.
-- 1: nums<sub>left</sub> is [<u><strong>0</strong></u>]. nums<sub>right</sub> is [0,<u><strong>1</strong></u>,0]. The score is 1 + 1 = 2.
-- 2: nums<sub>left</sub> is [<u><strong>0</strong></u>,<u><strong>0</strong></u>]. nums<sub>right</sub> is [<u><strong>1</strong></u>,0]. The score is 2 + 1 = 3.
-- 3: nums<sub>left</sub> is [<u><strong>0</strong></u>,<u><strong>0</strong></u>,1]. nums<sub>right</sub> is [0]. The score is 2 + 0 = 2.
-- 4: nums<sub>left</sub> is [<u><strong>0</strong></u>,<u><strong>0</strong></u>,1,<u><strong>0</strong></u>]. nums<sub>right</sub> is []. The score is 3 + 0 = 3.
-Indices 2 and 4 both have the highest possible division score 3.
-Note the answer [4,2] would also be accepted.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,0]
-<strong>Output:</strong> [3]
-<strong>Explanation:</strong> Division at index
-- 0: nums<sub>left</sub> is []. nums<sub>right</sub> is [0,0,0]. The score is 0 + 0 = 0.
-- 1: nums<sub>left</sub> is [<u><strong>0</strong></u>]. nums<sub>right</sub> is [0,0]. The score is 1 + 0 = 1.
-- 2: nums<sub>left</sub> is [<u><strong>0</strong></u>,<u><strong>0</strong></u>]. nums<sub>right</sub> is [0]. The score is 2 + 0 = 2.
-- 3: nums<sub>left</sub> is [<u><strong>0</strong></u>,<u><strong>0</strong></u>,<u><strong>0</strong></u>]. nums<sub>right</sub> is []. The score is 3 + 0 = 3.
-Only index 3 has the highest possible division score 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1]
-<strong>Output:</strong> [0]
-<strong>Explanation:</strong> Division at index
-- 0: nums<sub>left</sub> is []. nums<sub>right</sub> is [<u><strong>1</strong></u>,<u><strong>1</strong></u>]. The score is 0 + 2 = 2.
-- 1: nums<sub>left</sub> is [1]. nums<sub>right</sub> is [<u><strong>1</strong></u>]. The score is 0 + 1 = 1.
-- 2: nums<sub>left</sub> is [1,1]. nums<sub>right</sub> is []. The score is 0 + 0 = 0.
-Only index 0 has the highest possible division score 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums[i]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-When you iterate the array, maintain the number of zeros and ones on the left side. Can you quickly calculate the number of ones on the right side?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The number of ones on the right side equals the number of ones in the whole array minus the number of ones on the left side.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Alternatively, you can quickly calculate it by using a prefix sum array.
-</details>
diff --git a/problems/all-elements-in-two-binary-search-trees/README.md b/problems/all-elements-in-two-binary-search-trees/README.md
deleted file mode 100644
index add402354..000000000
--- a/problems/all-elements-in-two-binary-search-trees/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-n-unique-integers-sum-up-to-zero "Find N Unique Integers Sum up to Zero")
-　　　　　　　　　　　　　　　　
-[Next >](../jump-game-iii "Jump Game III")
-
-## [1305. All Elements in Two Binary Search Trees (Medium)](https://leetcode.com/problems/all-elements-in-two-binary-search-trees "两棵二叉搜索树中的所有元素")
-
-<p>Given two binary search trees <code>root1</code> and <code>root2</code>, return <em>a list containing all the integers from both trees sorted in <strong>ascending</strong> order</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/q2-e1.png" style="width: 457px; height: 207px;" />
-<pre>
-<strong>Input:</strong> root1 = [2,1,4], root2 = [1,0,3]
-<strong>Output:</strong> [0,1,1,2,3,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/q2-e5-.png" style="width: 352px; height: 197px;" />
-<pre>
-<strong>Input:</strong> root1 = [1,null,8], root2 = [8,1]
-<strong>Output:</strong> [1,1,8,8]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in each tree is in the range <code>[0, 5000]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Traverse the first tree in list1 and the second tree in list2.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Merge the two trees in one list and sort it.
-</details>
diff --git a/problems/all-nodes-distance-k-in-binary-tree/README.md b/problems/all-nodes-distance-k-in-binary-tree/README.md
deleted file mode 100644
index c312b5eab..000000000
--- a/problems/all-nodes-distance-k-in-binary-tree/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-subarray-with-sum-at-least-k "Shortest Subarray with Sum at Least K")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-path-to-get-all-keys "Shortest Path to Get All Keys")
-
-## [863. All Nodes Distance K in Binary Tree (Medium)](https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree "二叉树中所有距离为 K 的结点")
-
-<p>Given the <code>root</code> of a binary tree, the value of a target node <code>target</code>, and an integer <code>k</code>, return <em>an array of the values of all nodes that have a distance </em><code>k</code><em> from the target node.</em></p>
-
-<p>You can return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/06/28/sketch0.png" style="width: 500px; height: 429px;" />
-<pre>
-<strong>Input:</strong> root = [3,5,1,6,2,0,8,null,null,7,4], target = 5, k = 2
-<strong>Output:</strong> [7,4,1]
-Explanation: The nodes that are a distance 2 from the target node (with value 5) have values 7, 4, and 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1], target = 1, k = 3
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 500]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 500</code></li>
-	<li>All the values <code>Node.val</code> are <strong>unique</strong>.</li>
-	<li><code>target</code> is the value of one of the nodes in the tree.</li>
-	<li><code>0 &lt;= k &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/all-nodes-distance-k-in-binary-tree/all_nodes_distance_k_in_binary_tree.go b/problems/all-nodes-distance-k-in-binary-tree/all_nodes_distance_k_in_binary_tree.go
deleted file mode 100644
index 4e29d0b4f..000000000
--- a/problems/all-nodes-distance-k-in-binary-tree/all_nodes_distance_k_in_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem863
diff --git a/problems/all-nodes-distance-k-in-binary-tree/all_nodes_distance_k_in_binary_tree_test.go b/problems/all-nodes-distance-k-in-binary-tree/all_nodes_distance_k_in_binary_tree_test.go
deleted file mode 100644
index 4e29d0b4f..000000000
--- a/problems/all-nodes-distance-k-in-binary-tree/all_nodes_distance_k_in_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem863
diff --git a/problems/all-oone-data-structure/README.md b/problems/all-oone-data-structure/README.md
deleted file mode 100644
index b1bf3b3fc..000000000
--- a/problems/all-oone-data-structure/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../encode-n-ary-tree-to-binary-tree "Encode N-ary Tree to Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-genetic-mutation "Minimum Genetic Mutation")
-
-## [432. All O`one Data Structure (Hard)](https://leetcode.com/problems/all-oone-data-structure "全 O(1) 的数据结构")
-
-<p>Design a data structure to store the strings&#39; count with the ability to return the strings with minimum and maximum counts.</p>
-
-<p>Implement the <code>AllOne</code> class:</p>
-
-<ul>
-	<li><code>AllOne()</code> Initializes the object of the data structure.</li>
-	<li><code>inc(String key)</code> Increments the count of the string <code>key</code> by <code>1</code>. If <code>key</code> does not exist in the data structure, insert it with count <code>1</code>.</li>
-	<li><code>dec(String key)</code> Decrements the count of the string <code>key</code> by <code>1</code>. If the count of <code>key</code> is <code>0</code> after the decrement, remove it from the data structure. It is guaranteed that <code>key</code> exists in the data structure before the decrement.</li>
-	<li><code>getMaxKey()</code> Returns one of the keys with the maximal count. If no element exists, return an empty string <code>&quot;&quot;</code>.</li>
-	<li><code>getMinKey()</code> Returns one of the keys with the minimum count. If no element exists, return an empty string <code>&quot;&quot;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;AllOne&quot;, &quot;inc&quot;, &quot;inc&quot;, &quot;getMaxKey&quot;, &quot;getMinKey&quot;, &quot;inc&quot;, &quot;getMaxKey&quot;, &quot;getMinKey&quot;]
-[[], [&quot;hello&quot;], [&quot;hello&quot;], [], [], [&quot;leet&quot;], [], []]
-<strong>Output</strong>
-[null, null, null, &quot;hello&quot;, &quot;hello&quot;, null, &quot;hello&quot;, &quot;leet&quot;]
-
-<strong>Explanation</strong>
-AllOne allOne = new AllOne();
-allOne.inc(&quot;hello&quot;);
-allOne.inc(&quot;hello&quot;);
-allOne.getMaxKey(); // return &quot;hello&quot;
-allOne.getMinKey(); // return &quot;hello&quot;
-allOne.inc(&quot;leet&quot;);
-allOne.getMaxKey(); // return &quot;hello&quot;
-allOne.getMinKey(); // return &quot;leet&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= key.length &lt;= 10</code></li>
-	<li><code>key</code> consists of lowercase English letters.</li>
-	<li>It is guaranteed that for each call to <code>dec</code>, <code>key</code> is existing in the data structure.</li>
-	<li>At most <code>5 * 10<sup>4</sup></code>&nbsp;calls will be made to <code>inc</code>, <code>dec</code>, <code>getMaxKey</code>, and <code>getMinKey</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Doubly-Linked List](../../tag/doubly-linked-list/README.md)]
diff --git a/problems/all-oone-data-structure/all_oone_data_structure.go b/problems/all-oone-data-structure/all_oone_data_structure.go
deleted file mode 100644
index a62225c93..000000000
--- a/problems/all-oone-data-structure/all_oone_data_structure.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem432
diff --git a/problems/all-oone-data-structure/all_oone_data_structure_test.go b/problems/all-oone-data-structure/all_oone_data_structure_test.go
deleted file mode 100644
index a62225c93..000000000
--- a/problems/all-oone-data-structure/all_oone_data_structure_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem432
diff --git a/problems/all-paths-from-source-lead-to-destination/README.md b/problems/all-paths-from-source-lead-to-destination/README.md
deleted file mode 100644
index 6f5e1223b..000000000
--- a/problems/all-paths-from-source-lead-to-destination/README.md
+++ /dev/null
@@ -1,107 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimize-rounding-error-to-meet-target "Minimize Rounding Error to Meet Target")
-　　　　　　　　　　　　　　　　
-[Next >](../missing-element-in-sorted-array "Missing Element in Sorted Array")
-
-## [1059. All Paths from Source Lead to Destination (Medium)](https://leetcode.com/problems/all-paths-from-source-lead-to-destination "从始点到终点的所有路径")
-
-<p>Given the <code>edges</code> of a directed graph, and two nodes <code>source</code> and <code>destination</code> of this graph, determine whether or not all paths starting from <code>source</code> eventually end at <code>destination</code>, that is:</p>
-
-<ul>
-	<li>At least one path exists from the <code>source</code> node to the <code>destination</code> node</li>
-	<li>If a path exists from the <code>source</code> node to a node with no outgoing edges, then that node is equal to <code>destination</code>.</li>
-	<li>The number of possible paths from <code>source</code> to <code>destination</code> is a finite number.</li>
-</ul>
-
-<p>Return <code>true</code> if and only if all roads from <code>source</code> lead to <code>destination</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/16/485_example_1.png" style="width: 200px; height: 208px;" /></p>
-
-<pre>
-<strong>Input: </strong>n = 3, edges = <span id="example-input-1-2">[[0,1],[0,2]]</span>, source = <span id="example-input-1-3">0</span>, destination = 2
-<strong>Output: </strong><span id="example-output-1">false</span>
-<strong>Explanation: </strong>It is possible to reach and get stuck on both node 1 and node 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/16/485_example_2.png" style="width: 200px; height: 230px;" /></p>
-
-<pre>
-<strong>Input: </strong>n = <span id="example-input-2-1">4</span>, edges = <span id="example-input-2-2">[[0,1],[0,3],[1,2],[2,1]]</span>, source = <span id="example-input-2-3">0</span>, destination = <span id="example-input-2-4">3</span>
-<strong>Output: </strong><span id="example-output-2">false</span>
-<strong>Explanation: </strong>We have two possibilities: to end at node 3, or to loop over node 1 and node 2 indefinitely.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/16/485_example_3.png" style="width: 200px; height: 183px;" /></p>
-
-<pre>
-<strong>Input: </strong>n = <span id="example-input-3-1">4</span>, edges = <span id="example-input-3-2">[[0,1],[0,2],[1,3],[2,3]]</span>, source = <span id="example-input-3-3">0</span>, destination = <span id="example-input-3-4">3</span>
-<strong>Output: </strong><span id="example-output-3">true</span>
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/16/485_example_4.png" style="width: 200px; height: 183px;" /></p>
-
-<pre>
-<strong>Input: </strong>n = <span id="example-input-4-1">3</span>, edges = <span id="example-input-4-2">[[0,1],[1,1],[1,2]]</span>, source = <span id="example-input-4-3">0</span>, destination = <span id="example-input-4-4">2</span>
-<strong>Output: </strong><span id="example-output-4">false</span>
-<strong>Explanation: </strong>All paths from the source node end at the destination node, but there are an infinite number of paths, such as 0-1-2, 0-1-1-2, 0-1-1-1-2, 0-1-1-1-1-2, and so on.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/16/485_example_5.png" style="width: 150px; height: 131px;" /></p>
-
-<pre>
-<strong>Input: </strong>n = <span id="example-input-5-1">2</span>, edges = <span id="example-input-5-2">[[0,1],[1,1]]</span>, source = <span id="example-input-5-3">0</span>, destination = <span id="example-input-5-4">1</span>
-<strong>Output: </strong><span id="example-output-5">false</span>
-<strong>Explanation: </strong>There is infinite self-loop at destination node.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><italic>The given graph may have self loops and parallel edges.</italic></li>
-	<li>The number of nodes <code>n</code> in the graph is between <code>1</code> and <code>10000</code></li>
-	<li>The number of edges in the graph is between <code>0</code> and <code>10000</code></li>
-	<li><code>0 &lt;= edges.length &lt;= 10000</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>0 &lt;= source &lt;= n - 1</code></li>
-	<li><code>0 &lt;= destination &lt;= n - 1</code></li>
-</ol>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if we can reach to a cycle from the source node?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Then the answer will be false, because we eventually get trapped in the cycle forever.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What if the we can't reach to a cycle from the source node? Then we need to ensure that from all visited nodes from source the unique node with indegree = 0 is the destination node.
-</details>
diff --git a/problems/all-paths-from-source-to-target/README.md b/problems/all-paths-from-source-to-target/README.md
deleted file mode 100644
index 35dbddd71..000000000
--- a/problems/all-paths-from-source-to-target/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rotate-string "Rotate String")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-rotation-with-highest-score "Smallest Rotation with Highest Score")
-
-## [797. All Paths From Source to Target (Medium)](https://leetcode.com/problems/all-paths-from-source-to-target "所有可能的路径")
-
-<p>Given a directed acyclic graph (<strong>DAG</strong>) of <code>n</code> nodes labeled from <code>0</code> to <code>n - 1</code>, find all possible paths from node <code>0</code> to node <code>n - 1</code> and return them in <strong>any order</strong>.</p>
-
-<p>The graph is given as follows: <code>graph[i]</code> is a list of all nodes you can visit from node <code>i</code> (i.e., there is a directed edge from node <code>i</code> to node <code>graph[i][j]</code>).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/28/all_1.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> graph = [[1,2],[3],[3],[]]
-<strong>Output:</strong> [[0,1,3],[0,2,3]]
-<strong>Explanation:</strong> There are two paths: 0 -&gt; 1 -&gt; 3 and 0 -&gt; 2 -&gt; 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/28/all_2.jpg" style="width: 423px; height: 301px;" />
-<pre>
-<strong>Input:</strong> graph = [[4,3,1],[3,2,4],[3],[4],[]]
-<strong>Output:</strong> [[0,4],[0,3,4],[0,1,3,4],[0,1,2,3,4],[0,1,4]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> graph = [[1],[]]
-<strong>Output:</strong> [[0,1]]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> graph = [[1,2,3],[2],[3],[]]
-<strong>Output:</strong> [[0,1,2,3],[0,2,3],[0,3]]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> graph = [[1,3],[2],[3],[]]
-<strong>Output:</strong> [[0,1,2,3],[0,3]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == graph.length</code></li>
-	<li><code>2 &lt;= n &lt;= 15</code></li>
-	<li><code>0 &lt;= graph[i][j] &lt; n</code></li>
-	<li><code>graph[i][j] != i</code> (i.e., there will be no self-loops).</li>
-	<li>All the elements of <code>graph[i]</code> are <strong>unique</strong>.</li>
-	<li>The input graph is <strong>guaranteed</strong> to be a <strong>DAG</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [Number of Ways to Arrive at Destination](../number-of-ways-to-arrive-at-destination) (Medium)
diff --git a/problems/all-paths-from-source-to-target/all_paths_from_source_to_target.go b/problems/all-paths-from-source-to-target/all_paths_from_source_to_target.go
deleted file mode 100644
index 74b7b969a..000000000
--- a/problems/all-paths-from-source-to-target/all_paths_from_source_to_target.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem797
diff --git a/problems/all-paths-from-source-to-target/all_paths_from_source_to_target_test.go b/problems/all-paths-from-source-to-target/all_paths_from_source_to_target_test.go
deleted file mode 100644
index 74b7b969a..000000000
--- a/problems/all-paths-from-source-to-target/all_paths_from_source_to_target_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem797
diff --git a/problems/all-people-report-to-the-given-manager/README.md b/problems/all-people-report-to-the-given-manager/README.md
deleted file mode 100644
index e5e7d006b..000000000
--- a/problems/all-people-report-to-the-given-manager/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-stay-in-the-same-place-after-some-steps "Number of Ways to Stay in the Same Place After Some Steps")
-　　　　　　　　　　　　　　　　
-[Next >](../hexspeak "Hexspeak")
-
-## [1270. All People Report to the Given Manager (Medium)](https://leetcode.com/problems/all-people-report-to-the-given-manager "向公司CEO汇报工作的所有人")
-
-<p>Table: <code>Employees</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| employee_id   | int     |
-| employee_name | varchar |
-| manager_id    | int     |
-+---------------+---------+
-employee_id is the primary key for this table.
-Each row of this table indicates that the employee with ID employee_id and name employee_name reports his work to his/her direct manager with manager_id
-The head of the company is the employee with employee_id = 1.
-</pre> 
-
-Write an SQL query to find employee_id of all employees that directly or indirectly report their work to the head of the company.
-
-The indirect relation between managers will not exceed 3 managers as the company is small.
-
-Return result table in any order without duplicates.
-
-The query result format is in the following example:
-<pre>
-Employees table:
-+-------------+---------------+------------+
-| employee_id | employee_name | manager_id |
-+-------------+---------------+------------+
-| 1           | Boss          | 1          |
-| 3           | Alice         | 3          |
-| 2           | Bob           | 1          |
-| 4           | Daniel        | 2          |
-| 7           | Luis          | 4          |
-| 8           | Jhon          | 3          |
-| 9           | Angela        | 8          |
-| 77          | Robert        | 1          |
-+-------------+---------------+------------+
-
-Result table:
-+-------------+
-| employee_id |
-+-------------+
-| 2           |
-| 77          |
-| 4           |
-| 7           |
-+-------------+
-
-The head of the company is the employee with employee_id 1.
-The employees with employee_id 2 and 77 report their work directly to the head of the company.
-The employee with employee_id 4 report his work indirectly to the head of the company 4 --> 2 --> 1. 
-The employee with employee_id 7 report his work indirectly to the head of the company 7 --> 4 --> 2 --> 1.
-The employees with employee_id 3, 8 and 9 don't report their work to head of company directly or indirectly. 
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/all-people-report-to-the-given-manager/mysql_schemas.sql b/problems/all-people-report-to-the-given-manager/mysql_schemas.sql
deleted file mode 100644
index 25fc46e17..000000000
--- a/problems/all-people-report-to-the-given-manager/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Employees (employee_id int, employee_name varchar(30), manager_id int);
-Truncate table Employees;
-insert into Employees (employee_id, employee_name, manager_id) values ('1', 'Boss', '1');
-insert into Employees (employee_id, employee_name, manager_id) values ('3', 'Alice', '3');
-insert into Employees (employee_id, employee_name, manager_id) values ('2', 'Bob', '1');
-insert into Employees (employee_id, employee_name, manager_id) values ('4', 'Daniel', '2');
-insert into Employees (employee_id, employee_name, manager_id) values ('7', 'Luis', '4');
-insert into Employees (employee_id, employee_name, manager_id) values ('8', 'John', '3');
-insert into Employees (employee_id, employee_name, manager_id) values ('9', 'Angela', '8');
-insert into Employees (employee_id, employee_name, manager_id) values ('77', 'Robert', '1');
diff --git a/problems/all-possible-full-binary-trees/README.md b/problems/all-possible-full-binary-trees/README.md
deleted file mode 100644
index 663028786..000000000
--- a/problems/all-possible-full-binary-trees/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../groups-of-special-equivalent-strings "Groups of Special-Equivalent Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-frequency-stack "Maximum Frequency Stack")
-
-## [894. All Possible Full Binary Trees (Medium)](https://leetcode.com/problems/all-possible-full-binary-trees "所有可能的满二叉树")
-
-<p>Given an integer <code>n</code>, return <em>a list of all possible <strong>full binary trees</strong> with</em> <code>n</code> <em>nodes</em>. Each node of each tree in the answer must have <code>Node.val == 0</code>.</p>
-
-<p>Each element of the answer is the root node of one possible tree. You may return the final list of trees in <strong>any order</strong>.</p>
-
-<p>A <strong>full binary tree</strong> is a binary tree where each node has exactly <code>0</code> or <code>2</code> children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/08/22/fivetrees.png" style="width: 700px; height: 400px;" />
-<pre>
-<strong>Input:</strong> n = 7
-<strong>Output:</strong> [[0,0,0,null,null,0,0,null,null,0,0],[0,0,0,null,null,0,0,0,0],[0,0,0,0,0,0,0],[0,0,0,0,0,null,null,null,null,0,0],[0,0,0,0,0,null,null,0,0]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> [[0,0,0]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/all-possible-full-binary-trees/all_possible_full_binary_trees.go b/problems/all-possible-full-binary-trees/all_possible_full_binary_trees.go
deleted file mode 100644
index 3fc11d1d5..000000000
--- a/problems/all-possible-full-binary-trees/all_possible_full_binary_trees.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem894
diff --git a/problems/all-possible-full-binary-trees/all_possible_full_binary_trees_test.go b/problems/all-possible-full-binary-trees/all_possible_full_binary_trees_test.go
deleted file mode 100644
index 3fc11d1d5..000000000
--- a/problems/all-possible-full-binary-trees/all_possible_full_binary_trees_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem894
diff --git a/problems/all-the-pairs-with-the-maximum-number-of-common-followers/README.md b/problems/all-the-pairs-with-the-maximum-number-of-common-followers/README.md
deleted file mode 100644
index 85484c71c..000000000
--- a/problems/all-the-pairs-with-the-maximum-number-of-common-followers/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-of-minimum-values-in-all-subarrays "Maximum of Minimum Values in All Subarrays")
-　　　　　　　　　　　　　　　　
-[Next >](../three-divisors "Three Divisors")
-
-## [1951. All the Pairs With the Maximum Number of Common Followers (Medium)](https://leetcode.com/problems/all-the-pairs-with-the-maximum-number-of-common-followers "查询具有最多共同关注者的所有两两结对组")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/all-the-pairs-with-the-maximum-number-of-common-followers/mysql_schemas.sql b/problems/all-the-pairs-with-the-maximum-number-of-common-followers/mysql_schemas.sql
deleted file mode 100644
index 358f44061..000000000
--- a/problems/all-the-pairs-with-the-maximum-number-of-common-followers/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Relations (user_id int, follower_id int);
-Truncate table Relations;
-insert into Relations (user_id, follower_id) values ('1', '3');
-insert into Relations (user_id, follower_id) values ('2', '3');
-insert into Relations (user_id, follower_id) values ('7', '3');
-insert into Relations (user_id, follower_id) values ('1', '4');
-insert into Relations (user_id, follower_id) values ('2', '4');
-insert into Relations (user_id, follower_id) values ('7', '4');
-insert into Relations (user_id, follower_id) values ('1', '5');
-insert into Relations (user_id, follower_id) values ('2', '6');
-insert into Relations (user_id, follower_id) values ('7', '5');
diff --git a/problems/all-valid-triplets-that-can-represent-a-country/README.md b/problems/all-valid-triplets-that-can-represent-a-country/README.md
deleted file mode 100644
index 30cf0bbaa..000000000
--- a/problems/all-valid-triplets-that-can-represent-a-country/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fancy-sequence "Fancy Sequence")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-substring-between-two-equal-characters "Largest Substring Between Two Equal Characters")
-
-## [1623. All Valid Triplets That Can Represent a Country (Easy)](https://leetcode.com/problems/all-valid-triplets-that-can-represent-a-country "三人国家代表队")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/all-valid-triplets-that-can-represent-a-country/mysql_schemas.sql b/problems/all-valid-triplets-that-can-represent-a-country/mysql_schemas.sql
deleted file mode 100644
index 9f28968ca..000000000
--- a/problems/all-valid-triplets-that-can-represent-a-country/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists SchoolA (student_id int, student_name varchar(20));
-Create table If Not Exists SchoolB (student_id int, student_name varchar(20));
-Create table If Not Exists SchoolC (student_id int, student_name varchar(20));
-Truncate table SchoolA;
-insert into SchoolA (student_id, student_name) values ('1', 'Alice');
-insert into SchoolA (student_id, student_name) values ('2', 'Bob');
-Truncate table SchoolB;
-insert into SchoolB (student_id, student_name) values ('3', 'Tom');
-Truncate table SchoolC;
-insert into SchoolC (student_id, student_name) values ('3', 'Tom');
-insert into SchoolC (student_id, student_name) values ('2', 'Jerry');
-insert into SchoolC (student_id, student_name) values ('10', 'Alice');
diff --git a/problems/allocate-mailboxes/README.md b/problems/allocate-mailboxes/README.md
deleted file mode 100644
index b0bd29e7e..000000000
--- a/problems/allocate-mailboxes/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-two-non-overlapping-sub-arrays-each-with-target-sum "Find Two Non-overlapping Sub-arrays Each With Target Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../sales-by-day-of-the-week "Sales by Day of the Week")
-
-## [1478. Allocate Mailboxes (Hard)](https://leetcode.com/problems/allocate-mailboxes "安排邮筒")
-
-<p>Given the array <code>houses</code> where <code>houses[i]</code> is the location of the <code>i<sup>th</sup></code> house along a street and an integer <code>k</code>, allocate <code>k</code> mailboxes in the street.</p>
-
-<p>Return <em>the <strong>minimum</strong> total distance between each house and its nearest mailbox</em>.</p>
-
-<p>The test cases are generated so that the answer fits in a 32-bit integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/05/07/sample_11_1816.png" style="width: 454px; height: 154px;" />
-<pre>
-<strong>Input:</strong> houses = [1,4,8,10,20], k = 3
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Allocate mailboxes in position 3, 9 and 20.
-Minimum total distance from each houses to nearest mailboxes is |3-1| + |4-3| + |9-8| + |10-9| + |20-20| = 5 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/05/07/sample_2_1816.png" style="width: 433px; height: 154px;" />
-<pre>
-<strong>Input:</strong> houses = [2,3,5,12,18], k = 2
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> Allocate mailboxes in position 3 and 14.
-Minimum total distance from each houses to nearest mailboxes is |2-3| + |3-3| + |5-3| + |12-14| + |18-14| = 9.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= houses.length &lt;= 100</code></li>
-	<li><code>1 &lt;= houses[i] &lt;= 10<sup>4</sup></code></li>
-	<li>All the integers of <code>houses</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If k =1, the minimum distance is obtained allocating the mailbox in the median of the array houses.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Generalize this idea, using dynamic programming allocating k mailboxes.
-</details>
diff --git a/problems/alphabet-board-path/README.md b/problems/alphabet-board-path/README.md
deleted file mode 100644
index 6a4c93f65..000000000
--- a/problems/alphabet-board-path/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../n-th-tribonacci-number "N-th Tribonacci Number")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-1-bordered-square "Largest 1-Bordered Square")
-
-## [1138. Alphabet Board Path (Medium)](https://leetcode.com/problems/alphabet-board-path "字母板上的路径")
-
-<p>On an alphabet board, we start at position <code>(0, 0)</code>, corresponding to character&nbsp;<code>board[0][0]</code>.</p>
-
-<p>Here, <code>board = [&quot;abcde&quot;, &quot;fghij&quot;, &quot;klmno&quot;, &quot;pqrst&quot;, &quot;uvwxy&quot;, &quot;z&quot;]</code>, as shown in the diagram below.</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/07/28/azboard.png" style="width: 250px; height: 317px;" /></p>
-
-<p>We may make the following moves:</p>
-
-<ul>
-	<li><code>&#39;U&#39;</code> moves our position up one row, if the position exists on the board;</li>
-	<li><code>&#39;D&#39;</code> moves our position down one row, if the position exists on the board;</li>
-	<li><code>&#39;L&#39;</code> moves our position left one column, if the position exists on the board;</li>
-	<li><code>&#39;R&#39;</code> moves our position right one column, if the position exists on the board;</li>
-	<li><code>&#39;!&#39;</code>&nbsp;adds the character <code>board[r][c]</code> at our current position <code>(r, c)</code>&nbsp;to the&nbsp;answer.</li>
-</ul>
-
-<p>(Here, the only positions that exist on the board are positions with letters on them.)</p>
-
-<p>Return a sequence of moves that makes our answer equal to <code>target</code>&nbsp;in the minimum number of moves.&nbsp; You may return any path that does so.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> target = "leet"
-<strong>Output:</strong> "DDR!UURRR!!DDD!"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> target = "code"
-<strong>Output:</strong> "RR!DDRR!UUL!R!"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= target.length &lt;= 100</code></li>
-	<li><code>target</code> consists only of English lowercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create a hashmap from letter to position on the board.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Now for each letter, try moving there in steps, where at each step you check if it is inside the boundaries of the board.
-</details>
diff --git a/problems/alphabet-board-path/alphabet_board_path.go b/problems/alphabet-board-path/alphabet_board_path.go
deleted file mode 100644
index 53e45d526..000000000
--- a/problems/alphabet-board-path/alphabet_board_path.go
+++ /dev/null
@@ -1,42 +0,0 @@
-package problem1138
-
-import "strings"
-
-func alphabetBoardPath(target string) string {
-	var sb strings.Builder
-	// form [x1,y1] move to [x2,y2]
-	move := func(x1, y1, x2, y2 int) {
-		for y1 > y2 {
-			y1--
-			sb.WriteByte('L')
-		}
-		for x1 > x2 {
-			x1--
-			sb.WriteByte('U')
-		}
-		for x1 < x2 {
-			x1++
-			sb.WriteByte('D')
-		}
-		for y1 < y2 {
-			y1++
-			sb.WriteByte('R')
-		}
-		return
-	}
-
-	x1, y1 := 0, 0
-	for _, r := range target {
-		x2, y2 := coordinate(r)
-		move(x1, y1, x2, y2)
-		sb.WriteByte('!')
-		x1, y1 = x2, y2
-	}
-	return sb.String()
-}
-
-func coordinate(r rune) (x, y int) {
-	a := int(r - 'a')
-	x, y = a/5, a%5
-	return
-}
diff --git a/problems/ambiguous-coordinates/README.md b/problems/ambiguous-coordinates/README.md
deleted file mode 100644
index 9b197c55a..000000000
--- a/problems/ambiguous-coordinates/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bus-routes "Bus Routes")
-　　　　　　　　　　　　　　　　
-[Next >](../linked-list-components "Linked List Components")
-
-## [816. Ambiguous Coordinates (Medium)](https://leetcode.com/problems/ambiguous-coordinates "模糊坐标")
-
-<p>We had some 2-dimensional coordinates, like <code>&quot;(1, 3)&quot;</code> or <code>&quot;(2, 0.5)&quot;</code>. Then, we removed all commas, decimal points, and spaces and ended up with the string s.</p>
-
-<ul>
-	<li>For example, <code>&quot;(1, 3)&quot;</code> becomes <code>s = &quot;(13)&quot;</code> and <code>&quot;(2, 0.5)&quot;</code> becomes <code>s = &quot;(205)&quot;</code>.</li>
-</ul>
-
-<p>Return <em>a list of strings representing all possibilities for what our original coordinates could have been</em>.</p>
-
-<p>Our original representation never had extraneous zeroes, so we never started with numbers like <code>&quot;00&quot;</code>, <code>&quot;0.0&quot;</code>, <code>&quot;0.00&quot;</code>, <code>&quot;1.0&quot;</code>, <code>&quot;001&quot;</code>, <code>&quot;00.01&quot;</code>, or any other number that can be represented with fewer digits. Also, a decimal point within a number never occurs without at least one digit occurring before it, so we never started with numbers like <code>&quot;.1&quot;</code>.</p>
-
-<p>The final answer list can be returned in any order. All coordinates in the final answer have exactly one space between them (occurring after the comma.)</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(123)&quot;
-<strong>Output:</strong> [&quot;(1, 2.3)&quot;,&quot;(1, 23)&quot;,&quot;(1.2, 3)&quot;,&quot;(12, 3)&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(0123)&quot;
-<strong>Output:</strong> [&quot;(0, 1.23)&quot;,&quot;(0, 12.3)&quot;,&quot;(0, 123)&quot;,&quot;(0.1, 2.3)&quot;,&quot;(0.1, 23)&quot;,&quot;(0.12, 3)&quot;]
-<strong>Explanation:</strong> 0.0, 00, 0001 or 00.01 are not allowed.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(00011)&quot;
-<strong>Output:</strong> [&quot;(0, 0.011)&quot;,&quot;(0.001, 1)&quot;]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(100)&quot;
-<strong>Output:</strong> [&quot;(10, 0)&quot;]
-<strong>Explanation:</strong> 1.0 is not allowed.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>4 &lt;= s.length &lt;= 12</code></li>
-	<li><code>s[0] == &#39;(&#39;</code> and <code>s[s.length - 1] == &#39;)&#39;</code>.</li>
-	<li>The rest of <code>s</code> are digits.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
diff --git a/problems/ambiguous-coordinates/ambiguous_coordinates.go b/problems/ambiguous-coordinates/ambiguous_coordinates.go
deleted file mode 100644
index 2ba471c29..000000000
--- a/problems/ambiguous-coordinates/ambiguous_coordinates.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem816
diff --git a/problems/ambiguous-coordinates/ambiguous_coordinates_test.go b/problems/ambiguous-coordinates/ambiguous_coordinates_test.go
deleted file mode 100644
index 2ba471c29..000000000
--- a/problems/ambiguous-coordinates/ambiguous_coordinates_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem816
diff --git a/problems/amount-of-new-area-painted-each-day/README.md b/problems/amount-of-new-area-painted-each-day/README.md
deleted file mode 100644
index 7af517b36..000000000
--- a/problems/amount-of-new-area-painted-each-day/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../groups-of-strings "Groups of Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../order-two-columns-independently "Order Two Columns Independently")
-
-## [2158. Amount of New Area Painted Each Day (Hard)](https://leetcode.com/problems/amount-of-new-area-painted-each-day "")
-
-
-
-### Related Topics
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What’s a good way to keep track of intervals that you have already painted?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Create an array of all 1’s, and when you have painted an interval, set the values in that interval to 0.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Using this array, how can you quickly calculate the amount of new area that you paint on a given day?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Calculate the sum of the new array in the interval that you paint.
-</details>
diff --git a/problems/analyze-user-website-visit-pattern/README.md b/problems/analyze-user-website-visit-pattern/README.md
deleted file mode 100644
index e6a48d34d..000000000
--- a/problems/analyze-user-website-visit-pattern/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-swaps-to-group-all-1s-together "Minimum Swaps to Group All 1's Together")
-　　　　　　　　　　　　　　　　
-[Next >](../string-transforms-into-another-string "String Transforms Into Another String")
-
-## [1152. Analyze User Website Visit Pattern (Medium)](https://leetcode.com/problems/analyze-user-website-visit-pattern "用户网站访问行为分析")
-
-<p>We are given some website visits: the user with name&nbsp;<code>username[i]</code> visited the website&nbsp;<code>website[i]</code> at time <code>timestamp[i]</code>.</p>
-
-<p>A <em>3-sequence</em>&nbsp;is a list of&nbsp;websites of length 3 sorted in ascending order&nbsp;by the time of their visits.&nbsp; (The websites in a 3-sequence are not necessarily distinct.)</p>
-
-<p>Find the 3-sequence visited&nbsp;by the largest number of users. If there is more than one solution, return the lexicographically smallest such 3-sequence.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>username = <span>[&quot;joe&quot;,&quot;joe&quot;,&quot;joe&quot;,&quot;james&quot;,&quot;james&quot;,&quot;james&quot;,&quot;james&quot;,&quot;mary&quot;,&quot;mary&quot;,&quot;mary&quot;]</span>, timestamp = <span id="example-input-1-2">[1,2,3,4,5,6,7,8,9,10]</span>, website = <span id="example-input-1-3">[&quot;home&quot;,&quot;about&quot;,&quot;career&quot;,&quot;home&quot;,&quot;cart&quot;,&quot;maps&quot;,&quot;home&quot;,&quot;home&quot;,&quot;about&quot;,&quot;career&quot;]</span>
-<strong>Output: </strong><span id="example-output-1">[&quot;home&quot;,&quot;about&quot;,&quot;career&quot;]</span>
-<strong>Explanation: </strong>
-The tuples in this example are:
-[&quot;joe&quot;, 1, &quot;home&quot;]
-[&quot;joe&quot;, 2, &quot;about&quot;]
-[&quot;joe&quot;, 3, &quot;career&quot;]
-[&quot;james&quot;, 4, &quot;home&quot;]
-[&quot;james&quot;, 5, &quot;cart&quot;]
-[&quot;james&quot;, 6, &quot;maps&quot;]
-[&quot;james&quot;, 7, &quot;home&quot;]
-[&quot;mary&quot;, 8, &quot;home&quot;]
-[&quot;mary&quot;, 9, &quot;about&quot;]
-[&quot;mary&quot;, 10, &quot;career&quot;]
-The 3-sequence (&quot;home&quot;, &quot;about&quot;, &quot;career&quot;) was visited at least once by <strong>2</strong> users.
-The 3-sequence (&quot;home&quot;, &quot;cart&quot;, &quot;maps&quot;) was visited at least once by 1 user.
-The 3-sequence (&quot;home&quot;, &quot;cart&quot;, &quot;home&quot;) was visited at least once by 1 user.
-The 3-sequence (&quot;home&quot;, &quot;maps&quot;, &quot;home&quot;) was visited at least once by 1 user.
-The 3-sequence (&quot;cart&quot;, &quot;maps&quot;, &quot;home&quot;) was visited at least once by 1 user.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>3 &lt;= N = username.length = timestamp.length = website.length &lt;= 50</code></li>
-	<li><code>1 &lt;= username[i].length &lt;= 10</code></li>
-	<li><code>0 &lt;= timestamp[i] &lt;= 10^9</code></li>
-	<li><code>1 &lt;= website[i].length &lt;= 10</code></li>
-	<li>Both <code>username[i]</code> and <code>website[i]</code> contain only lowercase characters.</li>
-	<li>It is guaranteed that there is at least one user who visited at least 3 websites.</li>
-	<li>No user visits two websites at the same time.</li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's find for every user separately the websites he visited.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Consider all possible 3-sequences, find the number of distinct users who visited each of them.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How to check if some user visited some 3-sequence ?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Store for every user all the 3-sequence he visited.
-</details>
diff --git a/problems/android-unlock-patterns/README.md b/problems/android-unlock-patterns/README.md
deleted file mode 100644
index 681daf4dc..000000000
--- a/problems/android-unlock-patterns/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../intersection-of-two-arrays-ii "Intersection of Two Arrays II")
-　　　　　　　　　　　　　　　　
-[Next >](../data-stream-as-disjoint-intervals "Data Stream as Disjoint Intervals")
-
-## [351. Android Unlock Patterns (Medium)](https://leetcode.com/problems/android-unlock-patterns "安卓系统手势解锁")
-
-<p>Given an Android <b>3x3</b> key lock screen and two integers <b>m</b> and <b>n</b>, where 1 &le; m &le; n &le; 9, count the total number of unlock patterns of the Android lock screen, which consist of minimum of <b>m</b> keys and maximum <b>n</b> keys.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Rules for a valid pattern:</b></p>
-
-<ol>
-	<li>Each pattern must connect at least <b>m</b> keys and at most <b>n</b> keys.</li>
-	<li>All the keys must be distinct.</li>
-	<li>If the line connecting two consecutive keys in the pattern passes through any other keys, the other keys must have previously selected in the pattern. No jumps through non selected key is allowed.</li>
-	<li>The order of keys used matters.</li>
-</ol>
-
-<p>&nbsp;</p>
-
-<pre>
-<img src="https://assets.leetcode.com/uploads/2018/10/12/android-unlock.png" style="width: 418px; height: 128px;" /></pre>
-
-<p>&nbsp;</p>
-
-<p><b>Explanation:</b></p>
-
-<pre>
-| 1 | 2 | 3 |
-| 4 | 5 | 6 |
-| 7 | 8 | 9 |</pre>
-
-<p><b>Invalid move:</b> <code>4 - 1 - 3 - 6 </code><br />
-Line 1 - 3 passes through key 2 which had not been selected in the pattern.</p>
-
-<p><b>Invalid move:</b> <code>4 - 1 - 9 - 2</code><br />
-Line 1 - 9 passes through key 5 which had not been selected in the pattern.</p>
-
-<p><b>Valid move:</b> <code>2 - 4 - 1 - 3 - 6</code><br />
-Line 1 - 3 is valid because it passes through key 2, which had been selected in the pattern</p>
-
-<p><b>Valid move:</b> <code>6 - 5 - 4 - 1 - 9 - 2</code><br />
-Line 1 - 9 is valid because it passes through key 5, which had been selected in the pattern.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example:</strong></p>
-
-<div>
-<pre>
-<strong>Input: </strong>m = <span id="example-input-1-1">1</span>, n = <span id="example-input-1-2">1</span>
-<strong>Output: </strong><span id="example-output-1">9</span>
-</pre>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
diff --git a/problems/android-unlock-patterns/android_unlock_patterns.go b/problems/android-unlock-patterns/android_unlock_patterns.go
deleted file mode 100644
index 80010d0fd..000000000
--- a/problems/android-unlock-patterns/android_unlock_patterns.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem351
diff --git a/problems/android-unlock-patterns/android_unlock_patterns_test.go b/problems/android-unlock-patterns/android_unlock_patterns_test.go
deleted file mode 100644
index 80010d0fd..000000000
--- a/problems/android-unlock-patterns/android_unlock_patterns_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem351
diff --git a/problems/angle-between-hands-of-a-clock/README.md b/problems/angle-between-hands-of-a-clock/README.md
deleted file mode 100644
index a3bacec65..000000000
--- a/problems/angle-between-hands-of-a-clock/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold "Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold")
-　　　　　　　　　　　　　　　　
-[Next >](../jump-game-iv "Jump Game IV")
-
-## [1344. Angle Between Hands of a Clock (Medium)](https://leetcode.com/problems/angle-between-hands-of-a-clock "时钟指针的夹角")
-
-<p>Given two numbers, <code>hour</code> and <code>minutes</code>. Return the smaller angle (in degrees) formed between the <code>hour</code> and the <code>minute</code> hand.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/12/26/sample_1_1673.png" style="width: 230px; height: 225px;" /></p>
-
-<pre>
-<strong>Input:</strong> hour = 12, minutes = 30
-<strong>Output:</strong> 165
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/12/26/sample_2_1673.png" style="width: 230px; height: 225px;" /></p>
-
-<pre>
-<strong>Input:</strong> hour = 3, minutes = 30
-<strong>Output:</strong> 75
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/12/26/sample_3_1673.png" style="width: 230px; height: 225px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> hour = 3, minutes = 15
-<strong>Output:</strong> 7.5
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> hour = 4, minutes = 50
-<strong>Output:</strong> 155
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> hour = 12, minutes = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= hour &lt;= 12</code></li>
-	<li><code>0 &lt;= minutes &lt;= 59</code></li>
-	<li>Answers within&nbsp;<code>10^-5</code>&nbsp;of the actual value will be accepted as correct.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The tricky part is determining how the minute hand affects the position of the hour hand.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Calculate the angles separately then find the difference.
-</details>
diff --git a/problems/apples-oranges/README.md b/problems/apples-oranges/README.md
deleted file mode 100644
index 61bfaa61e..000000000
--- a/problems/apples-oranges/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-of-cutting-a-pizza "Number of Ways of Cutting a Pizza")
-　　　　　　　　　　　　　　　　
-[Next >](../consecutive-characters "Consecutive Characters")
-
-## [1445. Apples & Oranges (Medium)](https://leetcode.com/problems/apples-oranges "苹果和桔子")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/apples-oranges/mysql_schemas.sql b/problems/apples-oranges/mysql_schemas.sql
deleted file mode 100644
index 426703feb..000000000
--- a/problems/apples-oranges/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Sales (sale_date date, fruit ENUM('apples', 'oranges'), sold_num int);
-Truncate table Sales;
-insert into Sales (sale_date, fruit, sold_num) values ('2020-05-01', 'apples', '10');
-insert into Sales (sale_date, fruit, sold_num) values ('2020-05-01', 'oranges', '8');
-insert into Sales (sale_date, fruit, sold_num) values ('2020-05-02', 'apples', '15');
-insert into Sales (sale_date, fruit, sold_num) values ('2020-05-02', 'oranges', '15');
-insert into Sales (sale_date, fruit, sold_num) values ('2020-05-03', 'apples', '20');
-insert into Sales (sale_date, fruit, sold_num) values ('2020-05-03', 'oranges', '0');
-insert into Sales (sale_date, fruit, sold_num) values ('2020-05-04', 'apples', '15');
-insert into Sales (sale_date, fruit, sold_num) values ('2020-05-04', 'oranges', '16');
diff --git a/problems/apply-discount-every-n-orders/README.md b/problems/apply-discount-every-n-orders/README.md
deleted file mode 100644
index d43de40f0..000000000
--- a/problems/apply-discount-every-n-orders/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-integers-by-the-number-of-1-bits "Sort Integers by The Number of 1 Bits")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-substrings-containing-all-three-characters "Number of Substrings Containing All Three Characters")
-
-## [1357. Apply Discount Every n Orders (Medium)](https://leetcode.com/problems/apply-discount-every-n-orders "每隔 n 个顾客打折")
-
-<p>There is a supermarket that is frequented by many customers. The products sold at the supermarket are represented as two parallel integer arrays <code>products</code> and <code>prices</code>, where the <code>i<sup>th</sup></code> product has an ID of <code>products[i]</code> and a price of <code>prices[i]</code>.</p>
-
-<p>When a customer is paying, their bill is represented as two parallel integer arrays <code>product</code> and <code>amount</code>, where the <code>j<sup>th</sup></code> product they purchased has an ID of <code>product[j]</code>, and <code>amount[j]</code> is how much of the product they bought. Their subtotal is calculated as the sum of each <code>amount[j] * (price of the j<sup>th</sup> product)</code>.</p>
-
-<p>The supermarket decided to have a sale. Every <code>n<sup>th</sup></code> customer paying for their groceries will be given a <strong>percentage discount</strong>. The discount amount is given by <code>discount</code>, where they will be given <code>discount</code> percent off their subtotal. More formally, if their subtotal is <code>bill</code>, then they would actually pay <code>bill * ((100 - discount) / 100)</code>.</p>
-
-<p>Implement the <code>Cashier</code> class:</p>
-
-<ul>
-	<li><code>Cashier(int n, int discount, int[] products, int[] prices)</code> Initializes the object with <code>n</code>, the <code>discount</code>, and the <code>products</code> and their <code>prices</code>.</li>
-	<li><code>double getBill(int[] product, int[] amount)</code> Returns the final total of the bill with the discount applied (if any). Answers within <code>10<sup>-5</sup></code> of the actual value will be accepted.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Cashier&quot;,&quot;getBill&quot;,&quot;getBill&quot;,&quot;getBill&quot;,&quot;getBill&quot;,&quot;getBill&quot;,&quot;getBill&quot;,&quot;getBill&quot;]
-[[3,50,[1,2,3,4,5,6,7],[100,200,300,400,300,200,100]],[[1,2],[1,2]],[[3,7],[10,10]],[[1,2,3,4,5,6,7],[1,1,1,1,1,1,1]],[[4],[10]],[[7,3],[10,10]],[[7,5,3,1,6,4,2],[10,10,10,9,9,9,7]],[[2,3,5],[5,3,2]]]
-<strong>Output</strong>
-[null,500.0,4000.0,800.0,4000.0,4000.0,7350.0,2500.0]
-<strong>Explanation</strong>
-Cashier cashier = new Cashier(3,50,[1,2,3,4,5,6,7],[100,200,300,400,300,200,100]);
-cashier.getBill([1,2],[1,2]);                        // return 500.0. 1<sup>st</sup> customer, no discount.
-                                                     // bill = 1 * 100 + 2 * 200 = 500.
-cashier.getBill([3,7],[10,10]);                      // return 4000.0. 2<sup>nd</sup> customer, no discount.
-                                                     // bill = 10 * 300 + 10 * 100 = 4000.
-cashier.getBill([1,2,3,4,5,6,7],[1,1,1,1,1,1,1]);    // return 800.0. 3<sup>rd</sup> customer, 50% discount.
-                                                     // Original bill = 1600
-                                                     // Actual bill = 1600 * ((100 - 50) / 100) = 800.
-cashier.getBill([4],[10]);                           // return 4000.0. 4<sup>th</sup> customer, no discount.
-cashier.getBill([7,3],[10,10]);                      // return 4000.0. 5<sup>th</sup> customer, no discount.
-cashier.getBill([7,5,3,1,6,4,2],[10,10,10,9,9,9,7]); // return 7350.0. 6<sup>th</sup> customer, 50% discount.
-                                                     // Original bill = 14700, but with
-                                                     // Actual bill = 14700 * ((100 - 50) / 100) = 7350.
-cashier.getBill([2,3,5],[5,3,2]);                    // return 2500.0.  6<sup>th</sup> customer, no discount.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= discount &lt;= 100</code></li>
-	<li><code>1 &lt;= products.length &lt;= 200</code></li>
-	<li><code>prices.length == products.length</code></li>
-	<li><code>1 &lt;= products[i] &lt;= 200</code></li>
-	<li><code>1 &lt;= prices[i] &lt;= 1000</code></li>
-	<li>The elements in <code>products</code> are <strong>unique</strong>.</li>
-	<li><code>1 &lt;= product.length &lt;= products.length</code></li>
-	<li><code>amount.length == product.length</code></li>
-	<li><code>product[j]</code> exists in <code>products</code>.</li>
-	<li><code>1 &lt;= amount[j] &lt;= 1000</code></li>
-	<li>The elements of <code>product</code> are <strong>unique</strong>.</li>
-	<li>At most <code>1000</code> calls will be made to <code>getBill</code>.</li>
-	<li>Answers within <code>10<sup>-5</sup></code> of the actual value will be accepted.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep track of the count of the customers.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check if the count of the customers is divisible by n then apply the discount formula.
-</details>
diff --git a/problems/arithmetic-slices-ii-subsequence/README.md b/problems/arithmetic-slices-ii-subsequence/README.md
deleted file mode 100644
index 8481d5223..000000000
--- a/problems/arithmetic-slices-ii-subsequence/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-two-numbers-ii "Add Two Numbers II")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-boomerangs "Number of Boomerangs")
-
-## [446. Arithmetic Slices II - Subsequence (Hard)](https://leetcode.com/problems/arithmetic-slices-ii-subsequence "等差数列划分 II - 子序列")
-
-<p>Given an integer array <code>nums</code>, return <em>the number of all the <strong>arithmetic subsequences</strong> of</em> <code>nums</code>.</p>
-
-<p>A sequence of numbers is called arithmetic if it consists of <strong>at least three elements</strong> and if the difference between any two consecutive elements is the same.</p>
-
-<ul>
-	<li>For example, <code>[1, 3, 5, 7, 9]</code>, <code>[7, 7, 7, 7]</code>, and <code>[3, -1, -5, -9]</code> are arithmetic sequences.</li>
-	<li>For example, <code>[1, 1, 2, 5, 7]</code> is not an arithmetic sequence.</li>
-</ul>
-
-<p>A <strong>subsequence</strong> of an array is a sequence that can be formed by removing some elements (possibly none) of the array.</p>
-
-<ul>
-	<li>For example, <code>[2,5,10]</code> is a subsequence of <code>[1,2,1,<strong><u>2</u></strong>,4,1,<u><strong>5</strong></u>,<u><strong>10</strong></u>]</code>.</li>
-</ul>
-
-<p>The test cases are generated so that the answer fits in <strong>32-bit</strong> integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,4,6,8,10]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> All arithmetic subsequence slices are:
-[2,4,6]
-[4,6,8]
-[6,8,10]
-[2,4,6,8]
-[4,6,8,10]
-[2,4,6,8,10]
-[2,6,10]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,7,7,7,7]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> Any subsequence of this array is arithmetic.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1&nbsp; &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Arithmetic Slices](../arithmetic-slices) (Medium)
diff --git a/problems/arithmetic-slices-ii-subsequence/arithmetic_slices_ii_subsequence.go b/problems/arithmetic-slices-ii-subsequence/arithmetic_slices_ii_subsequence.go
deleted file mode 100644
index e0db175d9..000000000
--- a/problems/arithmetic-slices-ii-subsequence/arithmetic_slices_ii_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem446
diff --git a/problems/arithmetic-slices-ii-subsequence/arithmetic_slices_ii_subsequence_test.go b/problems/arithmetic-slices-ii-subsequence/arithmetic_slices_ii_subsequence_test.go
deleted file mode 100644
index e0db175d9..000000000
--- a/problems/arithmetic-slices-ii-subsequence/arithmetic_slices_ii_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem446
diff --git a/problems/arithmetic-slices/README.md b/problems/arithmetic-slices/README.md
deleted file mode 100644
index 90d411755..000000000
--- a/problems/arithmetic-slices/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fizz-buzz "Fizz Buzz")
-　　　　　　　　　　　　　　　　
-[Next >](../third-maximum-number "Third Maximum Number")
-
-## [413. Arithmetic Slices (Medium)](https://leetcode.com/problems/arithmetic-slices "等差数列划分")
-
-<p>An integer array is called arithmetic if it consists of <strong>at least three elements</strong> and if the difference between any two consecutive elements is the same.</p>
-
-<ul>
-	<li>For example, <code>[1,3,5,7,9]</code>, <code>[7,7,7,7]</code>, and <code>[3,-1,-5,-9]</code> are arithmetic sequences.</li>
-</ul>
-
-<p>Given an integer array <code>nums</code>, return <em>the number of arithmetic <strong>subarrays</strong> of</em> <code>nums</code>.</p>
-
-<p>A <strong>subarray</strong> is a contiguous subsequence of the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We have 3 arithmetic slices in nums: [1, 2, 3], [2, 3, 4] and [1,2,3,4] itself.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5000</code></li>
-	<li><code>-1000 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Arithmetic Slices II - Subsequence](../arithmetic-slices-ii-subsequence) (Hard)
-  1. [Arithmetic Subarrays](../arithmetic-subarrays) (Medium)
diff --git a/problems/arithmetic-slices/arithmetic_slices.go b/problems/arithmetic-slices/arithmetic_slices.go
deleted file mode 100644
index d1f411d21..000000000
--- a/problems/arithmetic-slices/arithmetic_slices.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem413
-
-func numberOfArithmeticSlices(A []int) int {
-	ans, i, j, l := 0, 0, 0, len(A)-1
-	for i < l-1 {
-		j = i + 1
-		for j < l && A[j+1]-A[j] == A[j]-A[j-1] {
-			j++
-		}
-		i, j = j, j-i
-		ans += j * (j - 1) / 2
-	}
-	return ans
-}
diff --git a/problems/arithmetic-slices/arithmetic_slices_test.go b/problems/arithmetic-slices/arithmetic_slices_test.go
deleted file mode 100644
index 8859800eb..000000000
--- a/problems/arithmetic-slices/arithmetic_slices_test.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package problem413
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestNumberOfArithmeticSlices(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 3, 5, 7, 9},
-			want: 6,
-		},
-		{
-			in:   []int{7, 7, 7, 7},
-			want: 3,
-		},
-		{
-			in:   []int{3, -1, -5, -9},
-			want: 3,
-		},
-		{
-			in:   []int{1, 2, 3, 4},
-			want: 3,
-		},
-		{
-			in:   []int{1, 2, 3, 4, 6, 8, 10},
-			want: 6,
-		},
-		{
-			in:   []int{1, 2},
-			want: 0,
-		},
-		{
-			in:   []int{1, 2, 4, 5, 7},
-			want: 0,
-		},
-	}
-	for _, tt := range tests {
-		got := numberOfArithmeticSlices(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/arithmetic-subarrays/README.md b/problems/arithmetic-subarrays/README.md
deleted file mode 100644
index e38ff7b32..000000000
--- a/problems/arithmetic-subarrays/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../slowest-key "Slowest Key")
-　　　　　　　　　　　　　　　　
-[Next >](../path-with-minimum-effort "Path With Minimum Effort")
-
-## [1630. Arithmetic Subarrays (Medium)](https://leetcode.com/problems/arithmetic-subarrays "等差子数组")
-
-<p>A sequence of numbers is called <strong>arithmetic</strong> if it consists of at least two elements, and the difference between every two consecutive elements is the same. More formally, a sequence <code>s</code> is arithmetic if and only if <code>s[i+1] - s[i] == s[1] - s[0] </code>for all valid <code>i</code>.</p>
-
-<p>For example, these are <strong>arithmetic</strong> sequences:</p>
-
-<pre>
-1, 3, 5, 7, 9
-7, 7, 7, 7
-3, -1, -5, -9</pre>
-
-<p>The following sequence is not <strong>arithmetic</strong>:</p>
-
-<pre>
-1, 1, 2, 5, 7</pre>
-
-<p>You are given an array of <code>n</code> integers, <code>nums</code>, and two arrays of <code>m</code> integers each, <code>l</code> and <code>r</code>, representing the <code>m</code> range queries, where the <code>i<sup>th</sup></code> query is the range <code>[l[i], r[i]]</code>. All the arrays are <strong>0-indexed</strong>.</p>
-
-<p>Return <em>a list of </em><code>boolean</code> <em>elements</em> <code>answer</code><em>, where</em> <code>answer[i]</code> <em>is</em> <code>true</code> <em>if the subarray</em> <code>nums[l[i]], nums[l[i]+1], ... , nums[r[i]]</code><em> can be <strong>rearranged</strong> to form an <strong>arithmetic</strong> sequence, and</em> <code>false</code> <em>otherwise.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = <code>[4,6,5,9,3,7]</code>, l = <code>[0,0,2]</code>, r = <code>[2,3,5]</code>
-<strong>Output:</strong> <code>[true,false,true]</code>
-<strong>Explanation:</strong>
-In the 0<sup>th</sup> query, the subarray is [4,6,5]. This can be rearranged as [6,5,4], which is an arithmetic sequence.
-In the 1<sup>st</sup> query, the subarray is [4,6,5,9]. This cannot be rearranged as an arithmetic sequence.
-In the 2<sup>nd</sup> query, the subarray is <code>[5,9,3,7]. This</code> can be rearranged as <code>[3,5,7,9]</code>, which is an arithmetic sequence.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-12,-9,-3,-12,-6,15,20,-25,-20,-15,-10], l = [0,1,6,4,8,7], r = [4,4,9,7,9,10]
-<strong>Output:</strong> [false,true,false,false,true,true]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>m == l.length</code></li>
-	<li><code>m == r.length</code></li>
-	<li><code>2 &lt;= n &lt;= 500</code></li>
-	<li><code>1 &lt;= m &lt;= 500</code></li>
-	<li><code>0 &lt;= l[i] &lt; r[i] &lt; n</code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-To check if a given sequence is arithmetic, just check that the difference between every two consecutive elements is the same.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If and only if a set of numbers can make an arithmetic sequence, then its sorted version makes an arithmetic sequence. So to check a set of numbers, sort it, and check if that sequence is arithmetic.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For each query, get the corresponding set of numbers which will be the sub-array represented by the query, sort it, and check if the result sequence is arithmetic.
-</details>
diff --git a/problems/armstrong-number/README.md b/problems/armstrong-number/README.md
deleted file mode 100644
index 6393d60cd..000000000
--- a/problems/armstrong-number/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-unique-number "Largest Unique Number")
-　　　　　　　　　　　　　　　　
-[Next >](../connecting-cities-with-minimum-cost "Connecting Cities With Minimum Cost")
-
-## [1134. Armstrong Number (Easy)](https://leetcode.com/problems/armstrong-number "阿姆斯特朗数")
-
-<p>The k-digit number <code>N</code> is an Armstrong number if and only if the k-th power of each digit sums to N.</p>
-
-<p>Given a positive integer <code>N</code>, return true if and only if it is an Armstrong number.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">153</span>
-<strong>Output: </strong><span id="example-output-1">true</span>
-<strong>Explanation: </strong>
-153 is a 3-digit number, and 153 = 1^3 + 5^3 + 3^3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">123</span>
-<strong>Output: </strong><span id="example-output-2">false</span>
-<strong>Explanation: </strong>
-123 is a 3-digit number, and 123 != 1^3 + 2^3 + 3^3 = 36.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= N &lt;= 10^8</code></li>
-</ol>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check if the given k-digit number equals the sum of the k-th power of it's digits.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How to compute the sum of the k-th power of the digits of a number ? Can you divide the number into digits using division and modulus operations ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can find the least significant digit of a number by taking it modulus 10. And you can remove it by dividing the number by 10 (integer division). Once you have a digit, you can raise it to the power of k and add it to the sum.
-</details>
diff --git a/problems/arranging-coins/README.md b/problems/arranging-coins/README.md
deleted file mode 100644
index 57ce5aa46..000000000
--- a/problems/arranging-coins/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-th-smallest-in-lexicographical-order "K-th Smallest in Lexicographical Order")
-　　　　　　　　　　　　　　　　
-[Next >](../find-all-duplicates-in-an-array "Find All Duplicates in an Array")
-
-## [441. Arranging Coins (Easy)](https://leetcode.com/problems/arranging-coins "排列硬币")
-
-<p>You have <code>n</code> coins and you want to build a staircase with these coins. The staircase consists of <code>k</code> rows where the <code>i<sup>th</sup></code> row has exactly <code>i</code> coins. The last row of the staircase <strong>may be</strong> incomplete.</p>
-
-<p>Given the integer <code>n</code>, return <em>the number of <strong>complete rows</strong> of the staircase you will build</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/09/arrangecoins1-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Because the 3<sup>rd</sup> row is incomplete, we return 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/09/arrangecoins2-grid.jpg" style="width: 333px; height: 333px;" />
-<pre>
-<strong>Input:</strong> n = 8
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Because the 4<sup>th</sup> row is incomplete, we return 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
diff --git a/problems/arranging-coins/arranging_coins.go b/problems/arranging-coins/arranging_coins.go
deleted file mode 100644
index 67eeb82e1..000000000
--- a/problems/arranging-coins/arranging_coins.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package problem441
-
-import "math"
-
-func arrangeCoins(n int) int {
-	x := math.Sqrt(1+8*float64(n)) - 1
-	return int(x) / 2
-}
diff --git a/problems/arranging-coins/arranging_coins_test.go b/problems/arranging-coins/arranging_coins_test.go
deleted file mode 100644
index e290120f8..000000000
--- a/problems/arranging-coins/arranging_coins_test.go
+++ /dev/null
@@ -1,51 +0,0 @@
-package problem441
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestArrangeCoins(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   5,
-			want: 2,
-		},
-		{
-			in:   8,
-			want: 3,
-		},
-		{
-			in:   0,
-			want: 0,
-		},
-		{
-			in:   1,
-			want: 1,
-		},
-		{
-			in:   2,
-			want: 1,
-		},
-		{
-			in:   3,
-			want: 2,
-		},
-		{
-			in:   13,
-			want: 4,
-		},
-		{
-			in:   130,
-			want: 15,
-		},
-	}
-	for _, tt := range tests {
-		got := arrangeCoins(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/array-nesting/README.md b/problems/array-nesting/README.md
deleted file mode 100644
index 8d0be2a7b..000000000
--- a/problems/array-nesting/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-closest-palindrome "Find the Closest Palindrome")
-　　　　　　　　　　　　　　　　
-[Next >](../reshape-the-matrix "Reshape the Matrix")
-
-## [565. Array Nesting (Medium)](https://leetcode.com/problems/array-nesting "数组嵌套")
-
-<p>You are given an integer array <code>nums</code> of length <code>n</code> where <code>nums</code> is a permutation of the numbers in the range <code>[0, n - 1]</code>.</p>
-
-<p>You should build a set <code>s[k] = {nums[k], nums[nums[k]], nums[nums[nums[k]]], ... }</code> subjected to the following rule:</p>
-
-<ul>
-	<li>The first element in <code>s[k]</code> starts with the selection of the element <code>nums[k]</code> of <code>index = k</code>.</li>
-	<li>The next element in <code>s[k]</code> should be <code>nums[nums[k]]</code>, and then <code>nums[nums[nums[k]]]</code>, and so on.</li>
-	<li>We stop adding right before a duplicate element occurs in <code>s[k]</code>.</li>
-</ul>
-
-<p>Return <em>the longest length of a set</em> <code>s[k]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,4,0,3,1,6,2]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> 
-nums[0] = 5, nums[1] = 4, nums[2] = 0, nums[3] = 3, nums[4] = 1, nums[5] = 6, nums[6] = 2.
-One of the longest sets s[k]:
-s[0] = {nums[0], nums[5], nums[6], nums[2]} = {5, 6, 2, 0}
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,2]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt; nums.length</code></li>
-	<li>All the values of <code>nums</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Nested List Weight Sum](../nested-list-weight-sum) (Medium)
-  1. [Flatten Nested List Iterator](../flatten-nested-list-iterator) (Medium)
-  1. [Nested List Weight Sum II](../nested-list-weight-sum-ii) (Medium)
diff --git a/problems/array-nesting/array_nesting.go b/problems/array-nesting/array_nesting.go
deleted file mode 100644
index c0dff58f4..000000000
--- a/problems/array-nesting/array_nesting.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem565
-
-func arrayNesting(nums []int) int {
-	ans := 0
-	for i := range nums {
-		c := 1
-		for nums[i] != i {
-			nums[i], nums[nums[i]] = nums[nums[i]], nums[i]
-			c++
-		}
-		if ans < c {
-			ans = c
-		}
-	}
-	return ans
-}
diff --git a/problems/array-nesting/array_nesting_test.go b/problems/array-nesting/array_nesting_test.go
deleted file mode 100644
index d9d3f068c..000000000
--- a/problems/array-nesting/array_nesting_test.go
+++ /dev/null
@@ -1,37 +0,0 @@
-package problem565
-
-import (
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestArrayNesting(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{5, 4, 0, 3, 1, 6, 2},
-			want: 4,
-		},
-		{
-			in:   []int{0, 3, 1, 5, 4, 6, 2},
-			want: 5,
-		},
-		{
-			in:   []int{6, 2, 5, 4, 0, 3, 1},
-			want: 7,
-		},
-		{
-			in:   []int{3, 1, 5, 4, 0, 6, 2},
-			want: 3,
-		},
-	}
-	for _, tt := range tests {
-		got := arrayNesting(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/array-of-doubled-pairs/README.md b/problems/array-of-doubled-pairs/README.md
deleted file mode 100644
index 7308b457d..000000000
--- a/problems/array-of-doubled-pairs/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../verifying-an-alien-dictionary "Verifying an Alien Dictionary")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-columns-to-make-sorted-ii "Delete Columns to Make Sorted II")
-
-## [954. Array of Doubled Pairs (Medium)](https://leetcode.com/problems/array-of-doubled-pairs "二倍数对数组")
-
-<p>Given an integer array of even length <code>arr</code>, return <code>true</code><em> if it is possible to reorder </em><code>arr</code><em> such that </em><code>arr[2 * i + 1] = 2 * arr[2 * i]</code><em> for every </em><code>0 &lt;= i &lt; len(arr) / 2</code><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,1,3,6]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,1,2,6]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,-2,2,-4]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We can take two groups, [-2,-4] and [2,4] to form [-2,-4,2,4] or [2,4,-2,-4].
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,4,16,8,4]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>arr.length</code> is even.</li>
-	<li><code>-10<sup>5</sup> &lt;= arr[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Find Original Array From Doubled Array](../find-original-array-from-doubled-array) (Medium)
diff --git a/problems/array-of-doubled-pairs/array_of_doubled_pairs.go b/problems/array-of-doubled-pairs/array_of_doubled_pairs.go
deleted file mode 100644
index 1ee16fc96..000000000
--- a/problems/array-of-doubled-pairs/array_of_doubled_pairs.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem954
diff --git a/problems/array-of-doubled-pairs/array_of_doubled_pairs_test.go b/problems/array-of-doubled-pairs/array_of_doubled_pairs_test.go
deleted file mode 100644
index 1ee16fc96..000000000
--- a/problems/array-of-doubled-pairs/array_of_doubled_pairs_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem954
diff --git a/problems/array-partition-i/README.md b/problems/array-partition-i/README.md
deleted file mode 100644
index bf1e259b2..000000000
--- a/problems/array-partition-i/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subarray-sum-equals-k "Subarray Sum Equals K")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-line-of-consecutive-one-in-matrix "Longest Line of Consecutive One in Matrix")
-
-## [561. Array Partition I (Easy)](https://leetcode.com/problems/array-partition-i "数组拆分 I")
-
-<p>Given an integer array <code>nums</code> of <code>2n</code> integers, group these integers into <code>n</code> pairs <code>(a<sub>1</sub>, b<sub>1</sub>), (a<sub>2</sub>, b<sub>2</sub>), ..., (a<sub>n</sub>, b<sub>n</sub>)</code> such that the sum of <code>min(a<sub>i</sub>, b<sub>i</sub>)</code> for all <code>i</code> is <strong>maximized</strong>. Return<em> the maximized sum</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,4,3,2]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> All possible pairings (ignoring the ordering of elements) are:
-1. (1, 4), (2, 3) -&gt; min(1, 4) + min(2, 3) = 1 + 2 = 3
-2. (1, 3), (2, 4) -&gt; min(1, 3) + min(2, 4) = 1 + 2 = 3
-3. (1, 2), (3, 4) -&gt; min(1, 2) + min(3, 4) = 1 + 3 = 4
-So the maximum possible sum is 4.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [6,2,6,5,1,2]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> The optimal pairing is (2, 1), (2, 5), (6, 6). min(2, 1) + min(2, 5) + min(6, 6) = 1 + 2 + 6 = 9.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>nums.length == 2 * n</code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Counting Sort](../../tag/counting-sort/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Obviously, brute force won't help here. Think of something else, take some example like 1,2,3,4.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How will you make pairs to get the result? There must be some pattern.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Did you observe that- Minimum element gets add into the result in sacrifice of maximum element.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Still won't able to find pairs? Sort the array and try to find the pattern.
-</details>
diff --git a/problems/array-partition-i/array_partition_i.go b/problems/array-partition-i/array_partition_i.go
deleted file mode 100644
index 4deaaf2d8..000000000
--- a/problems/array-partition-i/array_partition_i.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem561
-
-import "sort"
-
-func arrayPairSum(nums []int) int {
-	sum := 0
-	sort.Ints(nums)
-	for i, v := range nums {
-		if i&1 == 0 {
-			sum += v
-		}
-	}
-	return sum
-}
diff --git a/problems/array-partition-i/array_partition_i_test.go b/problems/array-partition-i/array_partition_i_test.go
deleted file mode 100644
index 58d398f4b..000000000
--- a/problems/array-partition-i/array_partition_i_test.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem561
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestArrayPairSum(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 4, 3, 2},
-			want: 4,
-		},
-	}
-	for _, tt := range tests {
-		got := arrayPairSum(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/array-transformation/README.md b/problems/array-transformation/README.md
deleted file mode 100644
index b4fcc4466..000000000
--- a/problems/array-transformation/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../web-crawler-multithreaded "Web Crawler Multithreaded")
-　　　　　　　　　　　　　　　　
-[Next >](../design-a-leaderboard "Design A Leaderboard")
-
-## [1243. Array Transformation (Easy)](https://leetcode.com/problems/array-transformation "数组变换")
-
-<p>Given an initial array <code>arr</code>, every day you produce a new array using the array of the previous day.</p>
-
-<p>On the <code>i</code>-th day, you do the following operations on the array of day&nbsp;<code>i-1</code>&nbsp;to produce the array of day <code>i</code>:</p>
-
-<ol>
-	<li>If an element is smaller than both its left neighbor and its right neighbor, then this element is incremented.</li>
-	<li>If an element is bigger than both its left neighbor and its right neighbor, then this element is decremented.</li>
-	<li>The first&nbsp;and last elements never change.</li>
-</ol>
-
-<p>After some days, the array does not change. Return that final array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [6,2,3,4]
-<strong>Output:</strong> [6,3,3,4]
-<strong>Explanation: </strong>
-On the first day, the array is changed from [6,2,3,4] to [6,3,3,4].
-No more operations can be done to this array.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,6,3,4,3,5]
-<strong>Output:</strong> [1,4,4,4,4,5]
-<strong>Explanation: </strong>
-On the first day, the array is changed from [1,6,3,4,3,5] to [1,5,4,3,4,5].
-On the second day, the array is changed from [1,5,4,3,4,5] to [1,4,4,4,4,5].
-No more operations can be done to this array.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 100</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to simulate the process.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For every iteration, find the new array using the old one and the given rules.
-</details>
diff --git a/problems/array-with-elements-not-equal-to-average-of-neighbors/README.md b/problems/array-with-elements-not-equal-to-average-of-neighbors/README.md
deleted file mode 100644
index 25d9d3c60..000000000
--- a/problems/array-with-elements-not-equal-to-average-of-neighbors/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-strings-that-appear-as-substrings-in-word "Number of Strings That Appear as Substrings in Word")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-non-zero-product-of-the-array-elements "Minimum Non-Zero Product of the Array Elements")
-
-## [1968. Array With Elements Not Equal to Average of Neighbors (Medium)](https://leetcode.com/problems/array-with-elements-not-equal-to-average-of-neighbors "构造元素不等于两相邻元素平均值的数组")
-
-<p>You are given a <strong>0-indexed</strong> array <code>nums</code> of <strong>distinct</strong> integers. You want to rearrange the elements in the array such that every element in the rearranged array is <strong>not</strong> equal to the <strong>average</strong> of its neighbors.</p>
-
-<p>More formally, the rearranged array should have the property such that for every <code>i</code> in the range <code>1 &lt;= i &lt; nums.length - 1</code>, <code>(nums[i-1] + nums[i+1]) / 2</code> is <strong>not</strong> equal to <code>nums[i]</code>.</p>
-
-<p>Return <em><strong>any</strong> rearrangement of </em><code>nums</code><em> that meets the requirements</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5]
-<strong>Output:</strong> [1,2,4,5,3]
-<strong>Explanation:</strong>
-When i=1, nums[i] = 2, and the average of its neighbors is (1+4) / 2 = 2.5.
-When i=2, nums[i] = 4, and the average of its neighbors is (2+5) / 2 = 3.5.
-When i=3, nums[i] = 5, and the average of its neighbors is (4+3) / 2 = 3.5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [6,2,0,9,7]
-<strong>Output:</strong> [9,7,6,2,0]
-<strong>Explanation:</strong>
-When i=1, nums[i] = 7, and the average of its neighbors is (9+6) / 2 = 7.5.
-When i=2, nums[i] = 6, and the average of its neighbors is (7+2) / 2 = 4.5.
-When i=3, nums[i] = 2, and the average of its neighbors is (6+0) / 2 = 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A number can be the average of its neighbors if one neighbor is smaller than the number and the other is greater than the number.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can put numbers smaller than the median on odd indices and the rest on even indices.
-</details>
diff --git a/problems/article-views-i/README.md b/problems/article-views-i/README.md
deleted file mode 100644
index 8b68e333a..000000000
--- a/problems/article-views-i/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-chunked-palindrome-decomposition "Longest Chunked Palindrome Decomposition")
-　　　　　　　　　　　　　　　　
-[Next >](../article-views-ii "Article Views II")
-
-## [1148. Article Views I (Easy)](https://leetcode.com/problems/article-views-i "文章浏览 I")
-
-<p>Table: <code>Views</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| article_id    | int     |
-| author_id     | int     |
-| viewer_id     | int     |
-| view_date     | date    |
-+---------------+---------+
-There is no primary key for this table, it may have duplicate rows.
-Each row of this table indicates that some viewer viewed an article (written by some author) on some date. 
-Note that equal author_id and viewer_id indicate the same person.</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find all the authors that viewed at least one of their own articles, sorted in ascending order by their id.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Views table:
-+------------+-----------+-----------+------------+
-| article_id | author_id | viewer_id | view_date  |
-+------------+-----------+-----------+------------+
-| 1          | 3         | 5         | 2019-08-01 |
-| 1          | 3         | 6         | 2019-08-02 |
-| 2          | 7         | 7         | 2019-08-01 |
-| 2          | 7         | 6         | 2019-08-02 |
-| 4          | 7         | 1         | 2019-07-22 |
-| 3          | 4         | 4         | 2019-07-21 |
-| 3          | 4         | 4         | 2019-07-21 |
-+------------+-----------+-----------+------------+
-
-Result table:
-+------+
-| id   |
-+------+
-| 4    |
-| 7    |
-+------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/article-views-i/mysql_schemas.sql b/problems/article-views-i/mysql_schemas.sql
deleted file mode 100644
index 70943fd44..000000000
--- a/problems/article-views-i/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Views (article_id int, author_id int, viewer_id int, view_date date);
-Truncate table Views;
-insert into Views (article_id, author_id, viewer_id, view_date) values ('1', '3', '5', '2019-08-01');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('1', '3', '6', '2019-08-02');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('2', '7', '7', '2019-08-01');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('2', '7', '6', '2019-08-02');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('4', '7', '1', '2019-07-22');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('3', '4', '4', '2019-07-21');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('3', '4', '4', '2019-07-21');
diff --git a/problems/article-views-ii/README.md b/problems/article-views-ii/README.md
deleted file mode 100644
index 49af2063a..000000000
--- a/problems/article-views-ii/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../article-views-i "Article Views I")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-a-number-is-majority-element-in-a-sorted-array "Check If a Number Is Majority Element in a Sorted Array")
-
-## [1149. Article Views II (Medium)](https://leetcode.com/problems/article-views-ii "文章浏览 II")
-
-<p>Table: <code>Views</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| article_id    | int     |
-| author_id     | int     |
-| viewer_id     | int     |
-| view_date     | date    |
-+---------------+---------+
-There is no primary key for this table, it may have duplicate rows.
-Each row of this table indicates that some viewer viewed an article (written by some author) on some date. 
-Note that equal author_id and viewer_id indicate the same person.</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find all the people who viewed more than one article on the same date, sorted in ascending order by their id.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Views table:
-+------------+-----------+-----------+------------+
-| article_id | author_id | viewer_id | view_date  |
-+------------+-----------+-----------+------------+
-| 1          | 3         | 5         | 2019-08-01 |
-| 3          | 4         | 5         | 2019-08-01 |
-| 1          | 3         | 6         | 2019-08-02 |
-| 2          | 7         | 7         | 2019-08-01 |
-| 2          | 7         | 6         | 2019-08-02 |
-| 4          | 7         | 1         | 2019-07-22 |
-| 3          | 4         | 4         | 2019-07-21 |
-| 3          | 4         | 4         | 2019-07-21 |
-+------------+-----------+-----------+------------+
-
-Result table:
-+------+
-| id   |
-+------+
-| 5    |
-| 6    |
-+------+</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/article-views-ii/mysql_schemas.sql b/problems/article-views-ii/mysql_schemas.sql
deleted file mode 100644
index c0178ce47..000000000
--- a/problems/article-views-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Views (article_id int, author_id int, viewer_id int, view_date date);
-Truncate table Views;
-insert into Views (article_id, author_id, viewer_id, view_date) values ('1', '3', '5', '2019-08-01');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('3', '4', '5', '2019-08-01');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('1', '3', '6', '2019-08-02');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('2', '7', '7', '2019-08-01');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('2', '7', '6', '2019-08-02');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('4', '7', '1', '2019-07-22');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('3', '4', '4', '2019-07-21');
-insert into Views (article_id, author_id, viewer_id, view_date) values ('3', '4', '4', '2019-07-21');
diff --git a/problems/as-far-from-land-as-possible/README.md b/problems/as-far-from-land-as-possible/README.md
deleted file mode 100644
index f7b860658..000000000
--- a/problems/as-far-from-land-as-possible/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-level-sum-of-a-binary-tree "Maximum Level Sum of a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../last-substring-in-lexicographical-order "Last Substring in Lexicographical Order")
-
-## [1162. As Far from Land as Possible (Medium)](https://leetcode.com/problems/as-far-from-land-as-possible "地图分析")
-
-<p>Given an <code>n x n</code> <code>grid</code>&nbsp;containing only values <code>0</code> and <code>1</code>, where&nbsp;<code>0</code> represents water&nbsp;and <code>1</code> represents land, find a water cell such that its distance to the nearest land cell is maximized, and return the distance.&nbsp;If no land or water exists in the grid, return <code>-1</code>.</p>
-
-<p>The distance used in this problem is the Manhattan distance:&nbsp;the distance between two cells <code>(x0, y0)</code> and <code>(x1, y1)</code> is <code>|x0 - x1| + |y0 - y1|</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/05/03/1336_ex1.JPG" style="width: 185px; height: 87px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,0,1],[0,0,0],[1,0,1]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The cell (1, 1) is as far as possible from all the land with distance 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/05/03/1336_ex2.JPG" style="width: 184px; height: 87px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,0,0],[0,0,0],[0,0,0]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The cell (2, 2) is as far as possible from all the land with distance 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= n&nbsp;&lt;= 100</code></li>
-	<li><code>grid[i][j]</code>&nbsp;is <code>0</code> or <code>1</code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Shortest Distance from All Buildings](../shortest-distance-from-all-buildings) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you think of this problem in a backwards way ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Imagine expanding outward from each land cell. What kind of search does that ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use BFS starting from all land cells in the same time.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-When do you reach the furthest water cell?
-</details>
diff --git a/problems/assign-cookies/README.md b/problems/assign-cookies/README.md
deleted file mode 100644
index b2899d806..000000000
--- a/problems/assign-cookies/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../4sum-ii "4Sum II")
-　　　　　　　　　　　　　　　　
-[Next >](../132-pattern "132 Pattern")
-
-## [455. Assign Cookies (Easy)](https://leetcode.com/problems/assign-cookies "分发饼干")
-
-<p>Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie.</p>
-
-<p>Each child <code>i</code> has a greed factor <code>g[i]</code>, which is the minimum size of a cookie that the child will be content with; and each cookie <code>j</code> has a size <code>s[j]</code>. If <code>s[j] &gt;= g[i]</code>, we can assign the cookie <code>j</code> to the child <code>i</code>, and the child <code>i</code> will be content. Your goal is to maximize the number of your content children and output the maximum number.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> g = [1,2,3], s = [1,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You have 3 children and 2 cookies. The greed factors of 3 children are 1, 2, 3. 
-And even though you have 2 cookies, since their size is both 1, you could only make the child whose greed factor is 1 content.
-You need to output 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> g = [1,2], s = [1,2,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You have 2 children and 3 cookies. The greed factors of 2 children are 1, 2. 
-You have 3 cookies and their sizes are big enough to gratify all of the children, 
-You need to output 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= g.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= s.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= g[i], s[j] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/assign-cookies/assign_cookies.go b/problems/assign-cookies/assign_cookies.go
deleted file mode 100644
index d7870bbba..000000000
--- a/problems/assign-cookies/assign_cookies.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem455
-
-import "sort"
-
-func findContentChildren(g []int, s []int) int {
-	sort.Ints(g)
-	sort.Ints(s)
-	var ans, i, j int
-	for i < len(g) && j < len(s) {
-		if g[i] <= s[j] {
-			ans, i = ans+1, i+1
-		}
-		j++
-	}
-	return ans
-}
diff --git a/problems/assign-cookies/assign_cookies_test.go b/problems/assign-cookies/assign_cookies_test.go
deleted file mode 100644
index df6fa1b7e..000000000
--- a/problems/assign-cookies/assign_cookies_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem455
-
-import "testing"
-
-type testType struct {
-	g    []int
-	s    []int
-	want int
-}
-
-func TestFindContentChildren(t *testing.T) {
-	tests := [...]testType{
-		{
-			g:    []int{1, 2, 3},
-			s:    []int{1, 1},
-			want: 1,
-		},
-		{
-			g:    []int{1, 2},
-			s:    []int{1, 2, 3},
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := findContentChildren(tt.g, tt.s)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.g, got, tt.want)
-		}
-	}
-}
diff --git a/problems/asteroid-collision/README.md b/problems/asteroid-collision/README.md
deleted file mode 100644
index d86b379f9..000000000
--- a/problems/asteroid-collision/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sentence-similarity "Sentence Similarity")
-　　　　　　　　　　　　　　　　
-[Next >](../parse-lisp-expression "Parse Lisp Expression")
-
-## [735. Asteroid Collision (Medium)](https://leetcode.com/problems/asteroid-collision "行星碰撞")
-
-<p>We are given an array <code>asteroids</code> of integers representing asteroids in a row.</p>
-
-<p>For each asteroid, the absolute value represents its size, and the sign represents its direction (positive meaning right, negative meaning left). Each asteroid moves at the same speed.</p>
-
-<p>Find out the state of the asteroids after all collisions. If two asteroids meet, the smaller one will explode. If both are the same size, both will explode. Two asteroids moving in the same direction will never meet.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> asteroids = [5,10,-5]
-<strong>Output:</strong> [5,10]
-<b>Explanation:</b> The 10 and -5 collide resulting in 10. The 5 and 10 never collide.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> asteroids = [8,-8]
-<strong>Output:</strong> []
-<b>Explanation:</b> The 8 and -8 collide exploding each other.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> asteroids = [10,2,-5]
-<strong>Output:</strong> [10]
-<b>Explanation:</b> The 2 and -5 collide resulting in -5. The 10 and -5 collide resulting in 10.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> asteroids = [-2,-1,1,2]
-<strong>Output:</strong> [-2,-1,1,2]
-<b>Explanation:</b> The -2 and -1 are moving left, while the 1 and 2 are moving right. Asteroids moving the same direction never meet, so no asteroids will meet each other.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= asteroids.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-1000 &lt;= asteroids[i] &lt;= 1000</code></li>
-	<li><code>asteroids[i] != 0</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Can Place Flowers](../can-place-flowers) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Say a row of asteroids is stable.  What happens when a new asteroid is added on the right?
-</details>
diff --git a/problems/asteroid-collision/asteroid_collision.go b/problems/asteroid-collision/asteroid_collision.go
deleted file mode 100644
index 5d878d55e..000000000
--- a/problems/asteroid-collision/asteroid_collision.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem735
diff --git a/problems/asteroid-collision/asteroid_collision_test.go b/problems/asteroid-collision/asteroid_collision_test.go
deleted file mode 100644
index 5d878d55e..000000000
--- a/problems/asteroid-collision/asteroid_collision_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem735
diff --git a/problems/available-captures-for-rook/README.md b/problems/available-captures-for-rook/README.md
deleted file mode 100644
index d1375f510..000000000
--- a/problems/available-captures-for-rook/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-binary-tree-ii "Maximum Binary Tree II")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-merge-stones "Minimum Cost to Merge Stones")
-
-## [999. Available Captures for Rook (Easy)](https://leetcode.com/problems/available-captures-for-rook "可以被一步捕获的棋子数")
-
-<p>On an <code>8 x 8</code> chessboard, there is <strong>exactly one</strong> white rook <code>&#39;R&#39;</code> and some number of white bishops <code>&#39;B&#39;</code>, black pawns <code>&#39;p&#39;</code>, and empty squares <code>&#39;.&#39;</code>.</p>
-
-<p>When the rook moves, it chooses one of four cardinal directions (north, east, south, or west), then moves in that direction until it chooses to stop, reaches the edge of the board, captures a black pawn, or is blocked by a white bishop. A rook is considered <strong>attacking</strong> a pawn if the rook can capture the pawn on the rook&#39;s turn. The <strong>number of available captures</strong> for the white rook is the number of pawns that the rook is <strong>attacking</strong>.</p>
-
-<p>Return <em>the <strong>number of available captures</strong> for the white rook</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/20/1253_example_1_improved.PNG" style="width: 300px; height: 305px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;R&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;p&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> In this example, the rook is attacking all the pawns.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/19/1253_example_2_improved.PNG" style="width: 300px; height: 306px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;p&quot;,&quot;p&quot;,&quot;p&quot;,&quot;p&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;p&quot;,&quot;p&quot;,&quot;B&quot;,&quot;p&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;p&quot;,&quot;B&quot;,&quot;R&quot;,&quot;B&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;p&quot;,&quot;p&quot;,&quot;B&quot;,&quot;p&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;p&quot;,&quot;p&quot;,&quot;p&quot;,&quot;p&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The bishops are blocking the rook from attacking any of the pawns.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/20/1253_example_3_improved.PNG" style="width: 300px; height: 305px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;p&quot;,&quot;p&quot;,&quot;.&quot;,&quot;R&quot;,&quot;.&quot;,&quot;p&quot;,&quot;B&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;B&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;p&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The rook is attacking the pawns at positions b5, d6, and f5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>board.length == 8</code></li>
-	<li><code>board[i].length == 8</code></li>
-	<li><code>board[i][j]</code> is either <code>&#39;R&#39;</code>, <code>&#39;.&#39;</code>, <code>&#39;B&#39;</code>, or <code>&#39;p&#39;</code></li>
-	<li>There is exactly one cell with <code>board[i][j] == &#39;R&#39;</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/available-captures-for-rook/available_captures_for_rook.go b/problems/available-captures-for-rook/available_captures_for_rook.go
deleted file mode 100644
index 39d372526..000000000
--- a/problems/available-captures-for-rook/available_captures_for_rook.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem999
-
-func numRookCaptures(board [][]byte) int {
-	ans, rx, ry, left, up := 0, -1, -1, [8]int{}, [8]int{}
-	for i, row := range board {
-		for j, v := range row {
-			if rx == -1 {
-				if v == 'p' {
-					left[i], up[j] = 1, 1
-				} else if v == 'B' {
-					left[i], up[j] = 0, 0
-				} else if v == 'R' {
-					ans, rx, ry = left[i]+up[j], i, j
-				}
-			} else if i == rx {
-				if v == 'p' {
-					ans++
-				}
-				if v != '.' {
-					break
-				}
-			} else if j == ry {
-				if v == 'p' {
-					ans++
-				}
-				if v != '.' {
-					return ans
-				}
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/available-captures-for-rook/available_captures_for_rook_test.go b/problems/available-captures-for-rook/available_captures_for_rook_test.go
deleted file mode 100644
index 39348f3a6..000000000
--- a/problems/available-captures-for-rook/available_captures_for_rook_test.go
+++ /dev/null
@@ -1,71 +0,0 @@
-package problem999
-
-import "testing"
-
-type testType struct {
-	in   [][]byte
-	want int
-}
-
-func TestNumRookCaptures(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]byte{
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', '.', 'p', '.', '.', '.', '.'},
-				{'.', '.', '.', 'R', '.', '.', '.', 'p'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', '.', 'p', '.', '.', '.', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-			},
-			want: 3,
-		},
-		{
-			in: [][]byte{
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', 'p', 'p', 'p', 'p', 'p', '.', '.'},
-				{'.', 'p', 'p', 'B', 'p', 'p', '.', '.'},
-				{'.', 'p', 'B', 'R', 'B', 'p', '.', '.'},
-				{'.', 'p', 'p', 'B', 'p', 'p', '.', '.'},
-				{'.', 'p', 'p', 'p', 'p', 'p', '.', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-			},
-			want: 0,
-		},
-		{
-			in: [][]byte{
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', '.', 'p', '.', '.', '.', '.'},
-				{'.', '.', '.', 'p', '.', '.', '.', '.'},
-				{'p', 'p', '.', 'R', '.', 'p', 'B', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', '.', 'B', '.', '.', '.', '.'},
-				{'.', '.', '.', 'p', '.', '.', '.', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-			},
-			want: 3,
-		},
-		{
-			in: [][]byte{
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', '.', 'p', '.', '.', '.', '.'},
-				{'.', '.', '.', 'p', '.', '.', '.', '.'},
-				{'p', 'B', '.', 'R', '.', 'p', 'B', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-				{'.', '.', 'p', '.', 'p', '.', '.', '.'},
-				{'.', '.', '.', '.', '.', '.', '.', '.'},
-			},
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := numRookCaptures(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/average-height-of-buildings-in-each-segment/README.md b/problems/average-height-of-buildings-in-each-segment/README.md
deleted file mode 100644
index d47e0bd37..000000000
--- a/problems/average-height-of-buildings-in-each-segment/README.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-subsequence-repeated-k-times "Longest Subsequence Repeated k Times")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-difference-between-increasing-elements "Maximum Difference Between Increasing Elements")
-
-## [2015. Average Height of Buildings in Each Segment (Medium)](https://leetcode.com/problems/average-height-of-buildings-in-each-segment "")
-
-
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try sorting the start and end points of each building.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The naive solution is to go through each position on the street and keep track of the sum of all the buildings at that position and the number of buildings at that position.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How could we optimize that solution to pass?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-We don't need to go through every position, just the ones where a building starts or a building ends.
-</details>
diff --git a/problems/average-of-levels-in-binary-tree/README.md b/problems/average-of-levels-in-binary-tree/README.md
deleted file mode 100644
index aac5fb089..000000000
--- a/problems/average-of-levels-in-binary-tree/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../exclusive-time-of-functions "Exclusive Time of Functions")
-　　　　　　　　　　　　　　　　
-[Next >](../shopping-offers "Shopping Offers")
-
-## [637. Average of Levels in Binary Tree (Easy)](https://leetcode.com/problems/average-of-levels-in-binary-tree "二叉树的层平均值")
-
-Given the <code>root</code> of a binary tree, return <em>the average value of the nodes on each level in the form of an array</em>. Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/09/avg1-tree.jpg" style="width: 277px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,null,null,15,7]
-<strong>Output:</strong> [3.00000,14.50000,11.00000]
-Explanation: The average value of nodes on level 0 is 3, on level 1 is 14.5, and on level 2 is 11.
-Hence return [3, 14.5, 11].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/09/avg2-tree.jpg" style="width: 292px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,15,7]
-<strong>Output:</strong> [3.00000,14.50000,11.00000]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-2<sup>31</sup> &lt;= Node.val &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Level Order Traversal](../binary-tree-level-order-traversal) (Medium)
-  1. [Binary Tree Level Order Traversal II](../binary-tree-level-order-traversal-ii) (Medium)
diff --git a/problems/average-of-levels-in-binary-tree/average_of_levels_in_binary_tree.go b/problems/average-of-levels-in-binary-tree/average_of_levels_in_binary_tree.go
deleted file mode 100644
index a7ba56531..000000000
--- a/problems/average-of-levels-in-binary-tree/average_of_levels_in_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem637
diff --git a/problems/average-of-levels-in-binary-tree/average_of_levels_in_binary_tree_test.go b/problems/average-of-levels-in-binary-tree/average_of_levels_in_binary_tree_test.go
deleted file mode 100644
index a7ba56531..000000000
--- a/problems/average-of-levels-in-binary-tree/average_of_levels_in_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem637
diff --git a/problems/average-salary-departments-vs-company/README.md b/problems/average-salary-departments-vs-company/README.md
deleted file mode 100644
index 7e1bd353e..000000000
--- a/problems/average-salary-departments-vs-company/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../second-degree-follower "Second Degree Follower")
-　　　　　　　　　　　　　　　　
-[Next >](../add-bold-tag-in-string "Add Bold Tag in String")
-
-## [615. Average Salary: Departments VS Company (Hard)](https://leetcode.com/problems/average-salary-departments-vs-company "平均工资：部门与公司比较")
-
-Given two tables as below, write a query to display the comparison result (higher/lower/same) of the average salary of employees in a department to the company&#39;s average salary.
-<p>&nbsp;</p>
-Table: <code>salary</code>
-
-<pre>
-| id | employee_id | amount | pay_date   |
-|----|-------------|--------|------------|
-| 1  | 1           | 9000   | 2017-03-31 |
-| 2  | 2           | 6000   | 2017-03-31 |
-| 3  | 3           | 10000  | 2017-03-31 |
-| 4  | 1           | 7000   | 2017-02-28 |
-| 5  | 2           | 6000   | 2017-02-28 |
-| 6  | 3           | 8000   | 2017-02-28 |
-</pre>
-
-<p>&nbsp;</p>
-The <b>employee_id</b> column refers to the <b>employee_id</b> in the following table <code>employee</code>.
-
-<p>&nbsp;</p>
-
-<pre>
-| employee_id | department_id |
-|-------------|---------------|
-| 1           | 1             |
-| 2           | 2             |
-| 3           | 2             |
-</pre>
-
-<p>&nbsp;</p>
-So for the sample data above, the result is:
-
-<p>&nbsp;</p>
-
-<pre>
-| pay_month | department_id | comparison  |
-|-----------|---------------|-------------|
-| 2017-03   | 1             | higher      |
-| 2017-03   | 2             | lower       |
-| 2017-02   | 1             | same        |
-| 2017-02   | 2             | same        |
-</pre>
-
-<p>&nbsp;</p>
-<b>Explanation</b>
-
-<p>&nbsp;</p>
-In March, the company&#39;s average salary is (9000+6000+10000)/3 = 8333.33...
-
-<p>&nbsp;</p>
-The average salary for department &#39;1&#39; is 9000, which is the salary of <b>employee_id</b> &#39;1&#39; since there is only one employee in this department. So the comparison result is &#39;higher&#39; since 9000 &gt; 8333.33 obviously.
-
-<p>&nbsp;</p>
-The average salary of department &#39;2&#39; is (6000 + 10000)/2 = 8000, which is the average of <b>employee_id</b> &#39;2&#39; and &#39;3&#39;. So the comparison result is &#39;lower&#39; since 8000 &lt; 8333.33.
-
-<p>&nbsp;</p>
-With he same formula for the average salary comparison in February, the result is &#39;same&#39; since both the department &#39;1&#39; and &#39;2&#39; have the same average salary with the company, which is 7000.
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/average-salary-departments-vs-company/average_salary_departments_vs_company.sql b/problems/average-salary-departments-vs-company/average_salary_departments_vs_company.sql
deleted file mode 100644
index b0dd6d5bd..000000000
--- a/problems/average-salary-departments-vs-company/average_salary_departments_vs_company.sql
+++ /dev/null
@@ -1,29 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT
-  department_salary.pay_month,
-  department_id,
-  CASE
-  WHEN department_avg > company_avg
-    THEN 'higher'
-  WHEN department_avg < company_avg
-    THEN 'lower'
-  ELSE 'same'
-  END AS comparison
-FROM
-  (SELECT
-     department_id,
-     avg(amount)                    AS department_avg,
-     date_format(pay_date, '%Y-%m') AS pay_month
-   FROM salary
-     JOIN employee ON salary.employee_id = employee.employee_id
-   GROUP BY department_id, pay_month
-  ) AS department_salary
-  JOIN (
-         SELECT
-           avg(amount)                    AS company_avg,
-           date_format(pay_date, '%Y-%m') AS pay_month
-         FROM salary
-         GROUP BY date_format(pay_date, '%Y-%m')
-       ) AS company_salary
-    ON department_salary.pay_month = company_salary.pay_month;
diff --git a/problems/average-salary-departments-vs-company/mysql_schemas.sql b/problems/average-salary-departments-vs-company/mysql_schemas.sql
deleted file mode 100644
index 3ab9ca94f..000000000
--- a/problems/average-salary-departments-vs-company/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Salary (id int, employee_id int, amount int, pay_date date);
-Create table If Not Exists Employee (employee_id int, department_id int);
-Truncate table Salary;
-insert into Salary (id, employee_id, amount, pay_date) values ('1', '1', '9000', '2017/03/31');
-insert into Salary (id, employee_id, amount, pay_date) values ('2', '2', '6000', '2017/03/31');
-insert into Salary (id, employee_id, amount, pay_date) values ('3', '3', '10000', '2017/03/31');
-insert into Salary (id, employee_id, amount, pay_date) values ('4', '1', '7000', '2017/02/28');
-insert into Salary (id, employee_id, amount, pay_date) values ('5', '2', '6000', '2017/02/28');
-insert into Salary (id, employee_id, amount, pay_date) values ('6', '3', '8000', '2017/02/28');
-Truncate table Employee;
-insert into Employee (employee_id, department_id) values ('1', '1');
-insert into Employee (employee_id, department_id) values ('2', '2');
-insert into Employee (employee_id, department_id) values ('3', '2');
diff --git a/problems/average-salary-excluding-the-minimum-and-maximum-salary/README.md b/problems/average-salary-excluding-the-minimum-and-maximum-salary/README.md
deleted file mode 100644
index 239269d1b..000000000
--- a/problems/average-salary-excluding-the-minimum-and-maximum-salary/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../clone-n-ary-tree "Clone N-ary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../the-kth-factor-of-n "The kth Factor of n")
-
-## [1491. Average Salary Excluding the Minimum and Maximum Salary (Easy)](https://leetcode.com/problems/average-salary-excluding-the-minimum-and-maximum-salary "去掉最低工资和最高工资后的工资平均值")
-
-<p>You are given an array of <strong>unique</strong> integers <code>salary</code> where <code>salary[i]</code> is the salary of the <code>i<sup>th</sup></code> employee.</p>
-
-<p>Return <em>the average salary of employees excluding the minimum and maximum salary</em>. Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> salary = [4000,3000,1000,2000]
-<strong>Output:</strong> 2500.00000
-<strong>Explanation:</strong> Minimum salary and maximum salary are 1000 and 4000 respectively.
-Average salary excluding minimum and maximum salary is (2000+3000) / 2 = 2500
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> salary = [1000,2000,3000]
-<strong>Output:</strong> 2000.00000
-<strong>Explanation:</strong> Minimum salary and maximum salary are 1000 and 3000 respectively.
-Average salary excluding minimum and maximum salary is (2000) / 1 = 2000
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= salary.length &lt;= 100</code></li>
-	<li><code>1000 &lt;= salary[i] &lt;= 10<sup>6</sup></code></li>
-	<li>All the integers of <code>salary</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Get the total sum and subtract the minimum and maximum value in the array.  Finally divide the result by n - 2.
-</details>
diff --git a/problems/average-selling-price/README.md b/problems/average-selling-price/README.md
deleted file mode 100644
index 2801a6793..000000000
--- a/problems/average-selling-price/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-it-is-a-good-array "Check If It Is a Good Array")
-　　　　　　　　　　　　　　　　
-[Next >](../cells-with-odd-values-in-a-matrix "Cells with Odd Values in a Matrix")
-
-## [1251. Average Selling Price (Easy)](https://leetcode.com/problems/average-selling-price "平均售价")
-
-<p>Table: <code>Prices</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| product_id    | int     |
-| start_date    | date    |
-| end_date      | date    |
-| price         | int     |
-+---------------+---------+
-(product_id, start_date, end_date) is the primary key for this table.
-Each row of this table indicates the price of the product_id in the period from start_date to end_date.
-For each product_id there will be no two overlapping periods. That means there will be no two intersecting periods for the same product_id.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Table: <code>UnitsSold</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| product_id    | int     |
-| purchase_date | date    |
-| units         | int     |
-+---------------+---------+
-There is no primary key for this table, it may contain duplicates.
-Each row of this table indicates the date, units and product_id of each product sold. 
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find the average selling price for each product.</p>
-
-<p><code>average_price&nbsp;</code>should be&nbsp;<strong>rounded to 2 decimal places</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Prices table:
-+------------+------------+------------+--------+
-| product_id | start_date | end_date   | price  |
-+------------+------------+------------+--------+
-| 1          | 2019-02-17 | 2019-02-28 | 5      |
-| 1          | 2019-03-01 | 2019-03-22 | 20     |
-| 2          | 2019-02-01 | 2019-02-20 | 15     |
-| 2          | 2019-02-21 | 2019-03-31 | 30     |
-+------------+------------+------------+--------+
- 
-UnitsSold table:
-+------------+---------------+-------+
-| product_id | purchase_date | units |
-+------------+---------------+-------+
-| 1          | 2019-02-25    | 100   |
-| 1          | 2019-03-01    | 15    |
-| 2          | 2019-02-10    | 200   |
-| 2          | 2019-03-22    | 30    |
-+------------+---------------+-------+
-
-Result table:
-+------------+---------------+
-| product_id | average_price |
-+------------+---------------+
-| 1          | 6.96          |
-| 2          | 16.96         |
-+------------+---------------+
-Average selling price = Total Price of Product / Number of products sold.
-Average selling price for product 1 = ((100 * 5) + (15 *&nbsp;20)) / 115 =&nbsp;6.96
-Average selling price for product 2 = ((200 * 15) + (30&nbsp;* 30)) / 230 =&nbsp;16.96
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/average-selling-price/mysql_schemas.sql b/problems/average-selling-price/mysql_schemas.sql
deleted file mode 100644
index e4c3cf269..000000000
--- a/problems/average-selling-price/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Prices (product_id int, start_date date, end_date date, price int);
-Create table If Not Exists UnitsSold (product_id int, purchase_date date, units int);
-Truncate table Prices;
-insert into Prices (product_id, start_date, end_date, price) values ('1', '2019-02-17', '2019-02-28', '5');
-insert into Prices (product_id, start_date, end_date, price) values ('1', '2019-03-01', '2019-03-22', '20');
-insert into Prices (product_id, start_date, end_date, price) values ('2', '2019-02-01', '2019-02-20', '15');
-insert into Prices (product_id, start_date, end_date, price) values ('2', '2019-02-21', '2019-03-31', '30');
-Truncate table UnitsSold;
-insert into UnitsSold (product_id, purchase_date, units) values ('1', '2019-02-25', '100');
-insert into UnitsSold (product_id, purchase_date, units) values ('1', '2019-03-01', '15');
-insert into UnitsSold (product_id, purchase_date, units) values ('2', '2019-02-10', '200');
-insert into UnitsSold (product_id, purchase_date, units) values ('2', '2019-03-22', '30');
diff --git a/problems/average-time-of-process-per-machine/README.md b/problems/average-time-of-process-per-machine/README.md
deleted file mode 100644
index 0a4023215..000000000
--- a/problems/average-time-of-process-per-machine/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../correct-a-binary-tree "Correct a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-two-string-arrays-are-equivalent "Check If Two String Arrays are Equivalent")
-
-## [1661. Average Time of Process per Machine (Easy)](https://leetcode.com/problems/average-time-of-process-per-machine "每台机器的进程平均运行时间")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/average-time-of-process-per-machine/mysql_schemas.sql b/problems/average-time-of-process-per-machine/mysql_schemas.sql
deleted file mode 100644
index 7ae9bb48a..000000000
--- a/problems/average-time-of-process-per-machine/mysql_schemas.sql
+++ /dev/null
@@ -1,14 +0,0 @@
-Create table If Not Exists Activity (machine_id int, process_id int, activity_type ENUM('start', 'end'), timestamp float);
-Truncate table Activity;
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('0', '0', 'start', '0.712');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('0', '0', 'end', '1.52');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('0', '1', 'start', '3.14');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('0', '1', 'end', '4.12');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('1', '0', 'start', '0.55');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('1', '0', 'end', '1.55');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('1', '1', 'start', '0.43');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('1', '1', 'end', '1.42');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('2', '0', 'start', '4.1');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('2', '0', 'end', '4.512');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('2', '1', 'start', '2.5');
-insert into Activity (machine_id, process_id, activity_type, timestamp) values ('2', '1', 'end', '5');
diff --git a/problems/average-waiting-time/README.md b/problems/average-waiting-time/README.md
deleted file mode 100644
index d2cba9701..000000000
--- a/problems/average-waiting-time/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-students-unable-to-eat-lunch "Number of Students Unable to Eat Lunch")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-binary-string-after-change "Maximum Binary String After Change")
-
-## [1701. Average Waiting Time (Medium)](https://leetcode.com/problems/average-waiting-time "平均等待时间")
-
-<p>There is a restaurant with a single chef. You are given an array <code>customers</code>, where <code>customers[i] = [arrival<sub>i</sub>, time<sub>i</sub>]:</code></p>
-
-<ul>
-	<li><code>arrival<sub>i</sub></code> is the arrival time of the <code>i<sup>th</sup></code> customer. The arrival times are sorted in <strong>non-decreasing</strong> order.</li>
-	<li><code>time<sub>i</sub></code> is the time needed to prepare the order of the <code>i<sup>th</sup></code> customer.</li>
-</ul>
-
-<p>When a customer arrives, he gives the chef his order, and the chef starts preparing it once he is idle. The customer waits till the chef finishes preparing his order. The chef does not prepare food for more than one customer at a time. The chef prepares food for customers <strong>in the order they were given in the input</strong>.</p>
-
-<p>Return <em>the <strong>average</strong> waiting time of all customers</em>. Solutions within <code>10<sup>-5</sup></code> from the actual answer are considered accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> customers = [[1,2],[2,5],[4,3]]
-<strong>Output:</strong> 5.00000
-<strong>Explanation:
-</strong>1) The first customer arrives at time 1, the chef takes his order and starts preparing it immediately at time 1, and finishes at time 3, so the waiting time of the first customer is 3 - 1 = 2.
-2) The second customer arrives at time 2, the chef takes his order and starts preparing it at time 3, and finishes at time 8, so the waiting time of the second customer is 8 - 2 = 6.
-3) The third customer arrives at time 4, the chef takes his order and starts preparing it at time 8, and finishes at time 11, so the waiting time of the third customer is 11 - 4 = 7.
-So the average waiting time = (2 + 6 + 7) / 3 = 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> customers = [[5,2],[5,4],[10,3],[20,1]]
-<strong>Output:</strong> 3.25000
-<strong>Explanation:
-</strong>1) The first customer arrives at time 5, the chef takes his order and starts preparing it immediately at time 5, and finishes at time 7, so the waiting time of the first customer is 7 - 5 = 2.
-2) The second customer arrives at time 5, the chef takes his order and starts preparing it at time 7, and finishes at time 11, so the waiting time of the second customer is 11 - 5 = 6.
-3) The third customer arrives at time 10, the chef takes his order and starts preparing it at time 11, and finishes at time 14, so the waiting time of the third customer is 14 - 10 = 4.
-4) The fourth customer arrives at time 20, the chef takes his order and starts preparing it immediately at time 20, and finishes at time 21, so the waiting time of the fourth customer is 21 - 20 = 1.
-So the average waiting time = (2 + 6 + 4 + 1) / 4 = 3.25.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= customers.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arrival<sub>i</sub>, time<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li><code>arrival<sub>i&nbsp;</sub>&lt;= arrival<sub>i+1</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate on the customers, maintaining the time the chef will finish the previous orders.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If that time is before the current arrival time, the chef starts immediately. Else, the current customer waits till the chef finishes, and then the chef starts.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Update the running time by the time when the chef starts preparing + preparation time.
-</details>
diff --git a/problems/avoid-flood-in-the-city/README.md b/problems/avoid-flood-in-the-city/README.md
deleted file mode 100644
index fdd8339ce..000000000
--- a/problems/avoid-flood-in-the-city/README.md
+++ /dev/null
@@ -1,100 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../making-file-names-unique "Making File Names Unique")
-　　　　　　　　　　　　　　　　
-[Next >](../find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree "Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree")
-
-## [1488. Avoid Flood in The City (Medium)](https://leetcode.com/problems/avoid-flood-in-the-city "避免洪水泛滥")
-
-<p>Your country has an infinite number of lakes. Initially, all the lakes are empty, but when it rains over the <code>nth</code> lake, the <code>nth</code> lake becomes full of water. If it rains over a lake which is <strong>full of water</strong>, there will be a <strong>flood</strong>. Your goal is to avoid the flood in any lake.</p>
-
-<p>Given an integer array <code>rains</code> where:</p>
-
-<ul>
-	<li><code>rains[i] &gt; 0</code> means there will be rains over the <code>rains[i]</code> lake.</li>
-	<li><code>rains[i] == 0</code> means there are no rains this day and you can choose <strong>one lake</strong> this day and <strong>dry it</strong>.</li>
-</ul>
-
-<p>Return <em>an array <code>ans</code></em> where:</p>
-
-<ul>
-	<li><code>ans.length == rains.length</code></li>
-	<li><code>ans[i] == -1</code> if <code>rains[i] &gt; 0</code>.</li>
-	<li><code>ans[i]</code> is the lake you choose to dry in the <code>ith</code> day if <code>rains[i] == 0</code>.</li>
-</ul>
-
-<p>If there are multiple valid answers return <strong>any</strong> of them. If it is impossible to avoid flood return <strong>an empty array</strong>.</p>
-
-<p>Notice that if you chose to dry a full lake, it becomes empty, but if you chose to dry an empty lake, nothing changes. (see example 4)</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rains = [1,2,3,4]
-<strong>Output:</strong> [-1,-1,-1,-1]
-<strong>Explanation:</strong> After the first day full lakes are [1]
-After the second day full lakes are [1,2]
-After the third day full lakes are [1,2,3]
-After the fourth day full lakes are [1,2,3,4]
-There&#39;s no day to dry any lake and there is no flood in any lake.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rains = [1,2,0,0,2,1]
-<strong>Output:</strong> [-1,-1,2,1,-1,-1]
-<strong>Explanation:</strong> After the first day full lakes are [1]
-After the second day full lakes are [1,2]
-After the third day, we dry lake 2. Full lakes are [1]
-After the fourth day, we dry lake 1. There is no full lakes.
-After the fifth day, full lakes are [2].
-After the sixth day, full lakes are [1,2].
-It is easy that this scenario is flood-free. [-1,-1,1,2,-1,-1] is another acceptable scenario.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> rains = [1,2,0,1,2]
-<strong>Output:</strong> []
-<strong>Explanation:</strong> After the second day, full lakes are  [1,2]. We have to dry one lake in the third day.
-After that, it will rain over lakes [1,2]. It&#39;s easy to prove that no matter which lake you choose to dry in the 3rd day, the other one will flood.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rains.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= rains[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep An array of the last day there was rains over each city.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep an array of the days you can dry a lake when you face one.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-When it rains over a lake, check the first possible day you can dry this lake and assign this day to this lake.
-</details>
diff --git a/problems/backspace-string-compare/README.md b/problems/backspace-string-compare/README.md
deleted file mode 100644
index e5ba9c09d..000000000
--- a/problems/backspace-string-compare/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../guess-the-word "Guess the Word")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-mountain-in-array "Longest Mountain in Array")
-
-## [844. Backspace String Compare (Easy)](https://leetcode.com/problems/backspace-string-compare "比较含退格的字符串")
-
-<p>Given two strings <code>s</code> and <code>t</code>, return <code>true</code> <em>if they are equal when both are typed into empty text editors</em>. <code>&#39;#&#39;</code> means a backspace character.</p>
-
-<p>Note that after backspacing an empty text, the text will continue empty.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ab#c&quot;, t = &quot;ad#c&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Both s and t become &quot;ac&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ab##&quot;, t = &quot;c#d#&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Both s and t become &quot;&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a#c&quot;, t = &quot;b&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> s becomes &quot;c&quot; while t becomes &quot;b&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code><span>1 &lt;= s.length, t.length &lt;= 200</span></code></li>
-	<li><span><code>s</code> and <code>t</code> only contain lowercase letters and <code>&#39;#&#39;</code> characters.</span></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Can you solve it in <code>O(n)</code> time and <code>O(1)</code> space?</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/backspace-string-compare/backspace_string_compare.go b/problems/backspace-string-compare/backspace_string_compare.go
deleted file mode 100644
index 996e14c27..000000000
--- a/problems/backspace-string-compare/backspace_string_compare.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem844
diff --git a/problems/backspace-string-compare/backspace_string_compare_test.go b/problems/backspace-string-compare/backspace_string_compare_test.go
deleted file mode 100644
index 996e14c27..000000000
--- a/problems/backspace-string-compare/backspace_string_compare_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem844
diff --git a/problems/bag-of-tokens/README.md b/problems/bag-of-tokens/README.md
deleted file mode 100644
index e5400398d..000000000
--- a/problems/bag-of-tokens/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../most-stones-removed-with-same-row-or-column "Most Stones Removed with Same Row or Column")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-time-for-given-digits "Largest Time for Given Digits")
-
-## [948. Bag of Tokens (Medium)](https://leetcode.com/problems/bag-of-tokens "令牌放置")
-
-<p>You have an initial <strong>power</strong> of <code>power</code>, an initial <strong>score</strong> of <code>0</code>, and a bag of <code>tokens</code> where <code>tokens[i]</code> is the value of the <code>i<sup>th</sup></code> token (0-indexed).</p>
-
-<p>Your goal is to maximize your total <strong>score</strong> by potentially playing each token in one of two ways:</p>
-
-<ul>
-	<li>If your current <strong>power</strong> is at least <code>tokens[i]</code>, you may play the <code>i<sup>th</sup></code> token face up, losing <code>tokens[i]</code> <strong>power</strong> and gaining <code>1</code> <strong>score</strong>.</li>
-	<li>If your current <strong>score</strong> is at least <code>1</code>, you may play the <code>i<sup>th</sup></code> token face down, gaining <code>tokens[i]</code> <strong>power</strong> and losing <code>1</code> <strong>score</strong>.</li>
-</ul>
-
-<p>Each token may be played <strong>at most</strong> once and <strong>in any order</strong>. You do <strong>not</strong> have to play all the tokens.</p>
-
-<p>Return <em>the largest possible <strong>score</strong> you can achieve after playing any number of tokens</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tokens = [100], power = 50
-<strong>Output:</strong> 0
-<strong>Explanation</strong><strong>:</strong> Playing the only token in the bag is impossible because you either have too little power or too little score.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tokens = [100,200], power = 150
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Play the 0<sup>th</sup> token (100) face up, your power becomes 50 and score becomes 1.
-There is no need to play the 1<sup>st</sup> token since you cannot play it face up to add to your score.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> tokens = [100,200,300,400], power = 200
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Play the tokens in this order to get a score of 2:
-1. Play the 0<sup>th</sup> token (100) face up, your power becomes 100 and score becomes 1.
-2. Play the 3<sup>rd</sup> token (400) face down, your power becomes 500 and score becomes 0.
-3. Play the 1<sup>st</sup> token (200) face up, your power becomes 300 and score becomes 1.
-4. Play the 2<sup>nd </sup>token (300) face up, your power becomes 0 and score becomes 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= tokens.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= tokens[i],&nbsp;power &lt; 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/bag-of-tokens/bag_of_tokens.go b/problems/bag-of-tokens/bag_of_tokens.go
deleted file mode 100644
index 4f2d08f5f..000000000
--- a/problems/bag-of-tokens/bag_of_tokens.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem948
diff --git a/problems/bag-of-tokens/bag_of_tokens_test.go b/problems/bag-of-tokens/bag_of_tokens_test.go
deleted file mode 100644
index 4f2d08f5f..000000000
--- a/problems/bag-of-tokens/bag_of_tokens_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem948
diff --git a/problems/balance-a-binary-search-tree/README.md b/problems/balance-a-binary-search-tree/README.md
deleted file mode 100644
index 29cbd7b6c..000000000
--- a/problems/balance-a-binary-search-tree/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-a-stack-with-increment-operation "Design a Stack With Increment Operation")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-performance-of-a-team "Maximum Performance of a Team")
-
-## [1382. Balance a Binary Search Tree (Medium)](https://leetcode.com/problems/balance-a-binary-search-tree "将二叉搜索树变平衡")
-
-<p>Given the <code>root</code> of a binary search tree, return <em>a <strong>balanced</strong> binary search tree with the same node values</em>. If there is more than one answer, return <strong>any of them</strong>.</p>
-
-<p>A binary search tree is <strong>balanced</strong> if the depth of the two subtrees of every node never differs by more than <code>1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/10/balance1-tree.jpg" style="width: 500px; height: 319px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2,null,3,null,4,null,null]
-<strong>Output:</strong> [2,1,3,null,null,null,4]
-<b>Explanation:</b> This is not the only correct answer, [3,1,4,null,2] is also correct.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/10/balanced2-tree.jpg" style="width: 224px; height: 145px;" />
-<pre>
-<strong>Input:</strong> root = [2,1,3]
-<strong>Output:</strong> [2,1,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert the tree to a sorted array using an in-order traversal.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Construct a new balanced tree from the sorted array recursively.
-</details>
diff --git a/problems/balanced-binary-tree/README.md b/problems/balanced-binary-tree/README.md
deleted file mode 100644
index 22b4d5ef7..000000000
--- a/problems/balanced-binary-tree/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-sorted-list-to-binary-search-tree "Convert Sorted List to Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-depth-of-binary-tree "Minimum Depth of Binary Tree")
-
-## [110. Balanced Binary Tree (Easy)](https://leetcode.com/problems/balanced-binary-tree "平衡二叉树")
-
-<p>Given a binary tree, determine if it is height-balanced.</p>
-
-<p>For this problem, a height-balanced binary tree is defined as:</p>
-
-<blockquote>
-<p>a binary tree in which the left and right subtrees of <em>every</em> node differ in height by no more than 1.</p>
-</blockquote>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/06/balance_1.jpg" style="width: 342px; height: 221px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,null,null,15,7]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/06/balance_2.jpg" style="width: 452px; height: 301px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,2,3,3,null,null,4,4]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 5000]</code>.</li>
-	<li><code>-10<sup>4</sup> &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Maximum Depth of Binary Tree](../maximum-depth-of-binary-tree) (Easy)
diff --git a/problems/balanced-binary-tree/balanced_binary_tree.go b/problems/balanced-binary-tree/balanced_binary_tree.go
deleted file mode 100644
index 7b1ccbb96..000000000
--- a/problems/balanced-binary-tree/balanced_binary_tree.go
+++ /dev/null
@@ -1,38 +0,0 @@
-package problem110
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func isBalanced(root *TreeNode) bool {
-	if root != nil {
-		left := depth(root.Left)
-		right := depth(root.Right)
-		if left > right+1 || left < right-1 {
-			return false
-		}
-		return isBalanced(root.Left) && isBalanced(root.Right)
-	}
-	return true
-}
-
-func depth(root *TreeNode) int {
-	if root != nil {
-		left := depth(root.Left) + 1
-		right := depth(root.Right) + 1
-		if left > right {
-			return left
-		}
-		return right
-	}
-	return 0
-}
diff --git a/problems/balanced-binary-tree/balanced_binary_tree_test.go b/problems/balanced-binary-tree/balanced_binary_tree_test.go
deleted file mode 100644
index c5df3012b..000000000
--- a/problems/balanced-binary-tree/balanced_binary_tree_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem110
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestIsBalanced(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 9, 20, kit.NULL, kit.NULL, 15, 7},
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 2, 3, 3, kit.NULL, kit.NULL, 4, 4},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isBalanced(kit.SliceInt2TreeNode(tt.in))
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/bank-account-summary-ii/README.md b/problems/bank-account-summary-ii/README.md
deleted file mode 100644
index 485e97320..000000000
--- a/problems/bank-account-summary-ii/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-search-tree-iterator-ii "Binary Search Tree Iterator II")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-all-odd-length-subarrays "Sum of All Odd Length Subarrays")
-
-## [1587. Bank Account Summary II (Easy)](https://leetcode.com/problems/bank-account-summary-ii "银行账户概要 II")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/bank-account-summary-ii/mysql_schemas.sql b/problems/bank-account-summary-ii/mysql_schemas.sql
deleted file mode 100644
index a6c25623c..000000000
--- a/problems/bank-account-summary-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,14 +0,0 @@
-Create table If Not Exists Users (account int, name varchar(20));
-Create table If Not Exists Transactions (trans_id int, account int, amount int, transacted_on date);
-Truncate table Users;
-insert into Users (account, name) values ('900001', 'Alice');
-insert into Users (account, name) values ('900002', 'Bob');
-insert into Users (account, name) values ('900003', 'Charlie');
-Truncate table Transactions;
-insert into Transactions (trans_id, account, amount, transacted_on) values ('1', '900001', '7000', '2020-08-01');
-insert into Transactions (trans_id, account, amount, transacted_on) values ('2', '900001', '7000', '2020-09-01');
-insert into Transactions (trans_id, account, amount, transacted_on) values ('3', '900001', '-3000', '2020-09-02');
-insert into Transactions (trans_id, account, amount, transacted_on) values ('4', '900002', '1000', '2020-09-12');
-insert into Transactions (trans_id, account, amount, transacted_on) values ('5', '900003', '6000', '2020-08-07');
-insert into Transactions (trans_id, account, amount, transacted_on) values ('6', '900003', '6000', '2020-09-07');
-insert into Transactions (trans_id, account, amount, transacted_on) values ('7', '900003', '-4000', '2020-09-11');
diff --git a/problems/bank-account-summary/README.md b/problems/bank-account-summary/README.md
deleted file mode 100644
index bbd146880..000000000
--- a/problems/bank-account-summary/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../strings-differ-by-one-character "Strings Differ by One Character")
-　　　　　　　　　　　　　　　　
-[Next >](../thousand-separator "Thousand Separator")
-
-## [1555. Bank Account Summary (Medium)](https://leetcode.com/problems/bank-account-summary "银行账户概要")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/bank-account-summary/mysql_schemas.sql b/problems/bank-account-summary/mysql_schemas.sql
deleted file mode 100644
index 2397d1a15..000000000
--- a/problems/bank-account-summary/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Users (user_id int, user_name varchar(20), credit int)
-;
-Create table If Not Exists Transactions (trans_id int, paid_by int, paid_to int, amount int, transacted_on date);
-Truncate table Users;
-insert into Users (user_id, user_name, credit) values ('1', 'Moustafa', '100');
-insert into Users (user_id, user_name, credit) values ('2', 'Jonathan', '200');
-insert into Users (user_id, user_name, credit) values ('3', 'Winston', '10000');
-insert into Users (user_id, user_name, credit) values ('4', 'Luis', '800');
-Truncate table Transactions;
-insert into Transactions (trans_id, paid_by, paid_to, amount, transacted_on) values ('1', '1', '3', '400', '2020-08-01');
-insert into Transactions (trans_id, paid_by, paid_to, amount, transacted_on) values ('2', '3', '2', '500', '2020-08-02');
-insert into Transactions (trans_id, paid_by, paid_to, amount, transacted_on) values ('3', '2', '1', '200', '2020-08-03');
diff --git a/problems/base-7/README.md b/problems/base-7/README.md
deleted file mode 100644
index 9d65ffe95..000000000
--- a/problems/base-7/README.md
+++ /dev/null
@@ -1,32 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../next-greater-element-ii "Next Greater Element II")
-　　　　　　　　　　　　　　　　
-[Next >](../the-maze-ii "The Maze II")
-
-## [504. Base 7 (Easy)](https://leetcode.com/problems/base-7 "七进制数")
-
-<p>Given an integer <code>num</code>, return <em>a string of its <strong>base 7</strong> representation</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> num = 100
-<strong>Output:</strong> "202"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> num = -7
-<strong>Output:</strong> "-10"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-10<sup>7</sup> &lt;= num &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/base-7/base_7.go b/problems/base-7/base_7.go
deleted file mode 100644
index a33edf3b2..000000000
--- a/problems/base-7/base_7.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem504
-
-import "fmt"
-
-func convertToBase7(num int) string {
-	ans := ""
-	if num < 0 {
-		ans, num = "-", -num
-	}
-	if num >= 7 {
-		ans += convertToBase7(num / 7)
-	}
-	return ans + fmt.Sprintf("%c", '0'+num%7)
-}
diff --git a/problems/base-7/base_7_test.go b/problems/base-7/base_7_test.go
deleted file mode 100644
index 81e455a9a..000000000
--- a/problems/base-7/base_7_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem504
-
-import "testing"
-
-type testType struct {
-	in   int
-	want string
-}
-
-func TestConvertToBase7(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   100,
-			want: "202",
-		},
-		{
-			in:   -7,
-			want: "-10",
-		},
-		{
-			in:   -1,
-			want: "-1",
-		},
-		{
-			in:   0,
-			want: "0",
-		},
-	}
-	for _, tt := range tests {
-		got := convertToBase7(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/baseball-game/README.md b/problems/baseball-game/README.md
deleted file mode 100644
index 27f41d025..000000000
--- a/problems/baseball-game/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../next-closest-time "Next Closest Time")
-　　　　　　　　　　　　　　　　
-[Next >](../k-empty-slots "K Empty Slots")
-
-## [682. Baseball Game (Easy)](https://leetcode.com/problems/baseball-game "棒球比赛")
-
-<p>You are keeping score for a baseball game with strange rules. The game consists of several rounds, where the scores of past rounds may affect future rounds&#39; scores.</p>
-
-<p>At the beginning of the game, you start with an empty record. You are given a list of strings <code>ops</code>, where <code>ops[i]</code> is the <code>i<sup>th</sup></code> operation you must apply to the record and is one of the following:</p>
-
-<ol>
-	<li>An integer <code>x</code> - Record a new score of <code>x</code>.</li>
-	<li><code>&quot;+&quot;</code> - Record a new score that is the sum of the previous two scores. It is guaranteed there will always be two previous scores.</li>
-	<li><code>&quot;D&quot;</code> - Record a new score that is double the previous score. It is guaranteed there will always be a previous score.</li>
-	<li><code>&quot;C&quot;</code> - Invalidate the previous score, removing it from the record. It is guaranteed there will always be a previous score.</li>
-</ol>
-
-<p>Return <em>the sum of all the scores on the record</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> ops = [&quot;5&quot;,&quot;2&quot;,&quot;C&quot;,&quot;D&quot;,&quot;+&quot;]
-<strong>Output:</strong> 30
-<strong>Explanation:</strong>
-&quot;5&quot; - Add 5 to the record, record is now [5].
-&quot;2&quot; - Add 2 to the record, record is now [5, 2].
-&quot;C&quot; - Invalidate and remove the previous score, record is now [5].
-&quot;D&quot; - Add 2 * 5 = 10 to the record, record is now [5, 10].
-&quot;+&quot; - Add 5 + 10 = 15 to the record, record is now [5, 10, 15].
-The total sum is 5 + 10 + 15 = 30.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> ops = [&quot;5&quot;,&quot;-2&quot;,&quot;4&quot;,&quot;C&quot;,&quot;D&quot;,&quot;9&quot;,&quot;+&quot;,&quot;+&quot;]
-<strong>Output:</strong> 27
-<strong>Explanation:</strong>
-&quot;5&quot; - Add 5 to the record, record is now [5].
-&quot;-2&quot; - Add -2 to the record, record is now [5, -2].
-&quot;4&quot; - Add 4 to the record, record is now [5, -2, 4].
-&quot;C&quot; - Invalidate and remove the previous score, record is now [5, -2].
-&quot;D&quot; - Add 2 * -2 = -4 to the record, record is now [5, -2, -4].
-&quot;9&quot; - Add 9 to the record, record is now [5, -2, -4, 9].
-&quot;+&quot; - Add -4 + 9 = 5 to the record, record is now [5, -2, -4, 9, 5].
-&quot;+&quot; - Add 9 + 5 = 14 to the record, record is now [5, -2, -4, 9, 5, 14].
-The total sum is 5 + -2 + -4 + 9 + 5 + 14 = 27.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> ops = [&quot;1&quot;]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= ops.length &lt;= 1000</code></li>
-	<li><code>ops[i]</code> is <code>&quot;C&quot;</code>, <code>&quot;D&quot;</code>, <code>&quot;+&quot;</code>, or a string representing an integer in the range <code>[-3 * 10<sup>4</sup>, 3 * 10<sup>4</sup>]</code>.</li>
-	<li>For operation <code>&quot;+&quot;</code>, there will always be at least two previous scores on the record.</li>
-	<li>For operations <code>&quot;C&quot;</code> and <code>&quot;D&quot;</code>, there will always be at least one previous score on the record.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/baseball-game/baseball_game.go b/problems/baseball-game/baseball_game.go
deleted file mode 100644
index 14a6fa2a2..000000000
--- a/problems/baseball-game/baseball_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem682
diff --git a/problems/baseball-game/baseball_game_test.go b/problems/baseball-game/baseball_game_test.go
deleted file mode 100644
index 14a6fa2a2..000000000
--- a/problems/baseball-game/baseball_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem682
diff --git a/problems/basic-calculator-ii/README.md b/problems/basic-calculator-ii/README.md
deleted file mode 100644
index aa4ab58ff..000000000
--- a/problems/basic-calculator-ii/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../invert-binary-tree "Invert Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../summary-ranges "Summary Ranges")
-
-## [227. Basic Calculator II (Medium)](https://leetcode.com/problems/basic-calculator-ii "基本计算器 II")
-
-<p>Given a string <code>s</code> which represents an expression, <em>evaluate this expression and return its value</em>.&nbsp;</p>
-
-<p>The integer division should truncate toward zero.</p>
-
-<p>You may assume that the given expression is always valid. All intermediate results will be in the range of <code>[-2<sup>31</sup>, 2<sup>31</sup> - 1]</code>.</p>
-
-<p><strong>Note:</strong> You are not allowed to use any built-in function which evaluates strings as mathematical expressions, such as <code>eval()</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "3+2*2"
-<strong>Output:</strong> 7
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = " 3/2 "
-<strong>Output:</strong> 1
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s = " 3+5 / 2 "
-<strong>Output:</strong> 5
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 3 * 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of integers and operators <code>(&#39;+&#39;, &#39;-&#39;, &#39;*&#39;, &#39;/&#39;)</code> separated by some number of spaces.</li>
-	<li><code>s</code> represents <strong>a valid expression</strong>.</li>
-	<li>All the integers in the expression are non-negative integers in the range <code>[0, 2<sup>31</sup> - 1]</code>.</li>
-	<li>The answer is <strong>guaranteed</strong> to fit in a <strong>32-bit integer</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Basic Calculator](../basic-calculator) (Hard)
-  1. [Expression Add Operators](../expression-add-operators) (Hard)
-  1. [Basic Calculator III](../basic-calculator-iii) (Hard)
diff --git a/problems/basic-calculator-ii/basic_calculator_ii.go b/problems/basic-calculator-ii/basic_calculator_ii.go
deleted file mode 100644
index c8b91ea5e..000000000
--- a/problems/basic-calculator-ii/basic_calculator_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem227
diff --git a/problems/basic-calculator-ii/basic_calculator_ii_test.go b/problems/basic-calculator-ii/basic_calculator_ii_test.go
deleted file mode 100644
index c8b91ea5e..000000000
--- a/problems/basic-calculator-ii/basic_calculator_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem227
diff --git a/problems/basic-calculator-iii/README.md b/problems/basic-calculator-iii/README.md
deleted file mode 100644
index a11c8252e..000000000
--- a/problems/basic-calculator-iii/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../jewels-and-stones "Jewels and Stones")
-　　　　　　　　　　　　　　　　
-[Next >](../sliding-puzzle "Sliding Puzzle")
-
-## [772. Basic Calculator III (Hard)](https://leetcode.com/problems/basic-calculator-iii "基本计算器 III")
-
-<p>Implement a basic calculator to evaluate a simple expression string.</p>
-
-<p>The expression string may contain open <code>(</code> and closing parentheses <code>)</code>, the plus <code>+</code> or minus sign <code>-</code>, <strong>non-negative</strong> integers and empty spaces <code> </code>.</p>
-
-<p>The expression string contains only non-negative integers, <code>+</code>, <code>-</code>, <code>*</code>, <code>/</code> operators , open <code>(</code> and closing parentheses <code>)</code> and empty spaces <code> </code>. The integer division should truncate toward zero.</p>
-
-<p>You may assume that the given expression is always valid. All intermediate results will be in the range of <code>[-2147483648, 2147483647]</code>.</p>
-
-<p>Some examples:</p>
-
-<pre>
-&quot;1 + 1&quot; = 2
-&quot; 6-4 / 2 &quot; = 4
-&quot;2*(5+5*2)/3+(6/2+8)&quot; = 21
-&quot;(2+6* 3+5- (3*14/7+2)*5)+3&quot;=-12
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong> <strong>Do not</strong> use the <code>eval</code> built-in library function.</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Basic Calculator](../basic-calculator) (Hard)
-  1. [Basic Calculator II](../basic-calculator-ii) (Medium)
-  1. [Basic Calculator IV](../basic-calculator-iv) (Hard)
diff --git a/problems/basic-calculator-iii/basic_calculator_iii.go b/problems/basic-calculator-iii/basic_calculator_iii.go
deleted file mode 100644
index 6a25d40d5..000000000
--- a/problems/basic-calculator-iii/basic_calculator_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem772
diff --git a/problems/basic-calculator-iii/basic_calculator_iii_test.go b/problems/basic-calculator-iii/basic_calculator_iii_test.go
deleted file mode 100644
index 6a25d40d5..000000000
--- a/problems/basic-calculator-iii/basic_calculator_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem772
diff --git a/problems/basic-calculator-iv/README.md b/problems/basic-calculator-iv/README.md
deleted file mode 100644
index 6645b7aa6..000000000
--- a/problems/basic-calculator-iv/README.md
+++ /dev/null
@@ -1,126 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-chunks-to-make-sorted "Max Chunks To Make Sorted")
-　　　　　　　　　　　　　　　　
-[Next >](../jewels-and-stones "Jewels and Stones")
-
-## [770. Basic Calculator IV (Hard)](https://leetcode.com/problems/basic-calculator-iv "基本计算器 IV")
-
-<p>Given an expression such as <code>expression = &quot;e + 8 - a + 5&quot;</code> and an evaluation map such as <code>{&quot;e&quot;: 1}</code> (given in terms of <code>evalvars = [&quot;e&quot;]</code> and <code>evalints = [1]</code>), return a list of tokens representing the simplified expression, such as <code>[&quot;-1*a&quot;,&quot;14&quot;]</code></p>
-
-<ul>
-	<li>An expression alternates chunks and symbols, with a space separating each chunk and symbol.</li>
-	<li>A chunk is either an expression in parentheses, a variable, or a non-negative integer.</li>
-	<li>A variable is a string of lowercase letters (not including digits.) Note that variables can be multiple letters, and note that variables never have a leading coefficient or unary operator like <code>&quot;2x&quot;</code> or <code>&quot;-x&quot;</code>.</li>
-</ul>
-
-<p>Expressions are evaluated in the usual order: brackets first, then multiplication, then addition and subtraction.</p>
-
-<ul>
-	<li>For example, <code>expression = &quot;1 + 2 * 3&quot;</code> has an answer of <code>[&quot;7&quot;]</code>.</li>
-</ul>
-
-<p>The format of the output is as follows:</p>
-
-<ul>
-	<li>For each term of free variables with a non-zero coefficient, we write the free variables within a term in sorted order lexicographically.
-	<ul>
-		<li>For example, we would never write a term like <code>&quot;b*a*c&quot;</code>, only <code>&quot;a*b*c&quot;</code>.</li>
-	</ul>
-	</li>
-	<li>Terms have degrees equal to the number of free variables being multiplied, counting multiplicity. We write the largest degree terms of our answer first, breaking ties by lexicographic order ignoring the leading coefficient of the term.
-	<ul>
-		<li>For example, <code>&quot;a*a*b*c&quot;</code> has degree <code>4</code>.</li>
-	</ul>
-	</li>
-	<li>The leading coefficient of the term is placed directly to the left with an asterisk separating it from the variables (if they exist.) A leading coefficient of 1 is still printed.</li>
-	<li>An example of a well-formatted answer is <code>[&quot;-2*a*a*a&quot;, &quot;3*a*a*b&quot;, &quot;3*b*b&quot;, &quot;4*a&quot;, &quot;5*c&quot;, &quot;-6&quot;]</code>.</li>
-	<li>Terms (including constant terms) with coefficient <code>0</code> are not included.
-	<ul>
-		<li>For example, an expression of <code>&quot;0&quot;</code> has an output of <code>[]</code>.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;e + 8 - a + 5&quot;, evalvars = [&quot;e&quot;], evalints = [1]
-<strong>Output:</strong> [&quot;-1*a&quot;,&quot;14&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;e - 8 + temperature - pressure&quot;, evalvars = [&quot;e&quot;, &quot;temperature&quot;], evalints = [1, 12]
-<strong>Output:</strong> [&quot;-1*pressure&quot;,&quot;5&quot;]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;(e + 8) * (e - 8)&quot;, evalvars = [], evalints = []
-<strong>Output:</strong> [&quot;1*e*e&quot;,&quot;-64&quot;]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;a * b * c + b * a * c * 4&quot;, evalvars = [], evalints = []
-<strong>Output:</strong> [&quot;5*a*b*c&quot;]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;((a - b) * (b - c) + (c - a)) * ((a - b) + (b - c) * (c - a))&quot;, evalvars = [], evalints = []
-<strong>Output:</strong> [&quot;-1*a*a*b*b&quot;,&quot;2*a*a*b*c&quot;,&quot;-1*a*a*c*c&quot;,&quot;1*a*b*b*b&quot;,&quot;-1*a*b*b*c&quot;,&quot;-1*a*b*c*c&quot;,&quot;1*a*c*c*c&quot;,&quot;-1*b*b*b*c&quot;,&quot;2*b*b*c*c&quot;,&quot;-1*b*c*c*c&quot;,&quot;2*a*a*b&quot;,&quot;-2*a*a*c&quot;,&quot;-2*a*b*b&quot;,&quot;2*a*c*c&quot;,&quot;1*b*b*b&quot;,&quot;-1*b*b*c&quot;,&quot;1*b*c*c&quot;,&quot;-1*c*c*c&quot;,&quot;-1*a*a&quot;,&quot;1*a*b&quot;,&quot;1*a*c&quot;,&quot;-1*b*c&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= expression.length &lt;= 250</code></li>
-	<li><code>expression</code> consists of lowercase English letters, digits, <code>&#39;+&#39;</code>, <code>&#39;-&#39;</code>, <code>&#39;*&#39;</code>, <code>&#39;(&#39;</code>, <code>&#39;)&#39;</code>, <code>&#39; &#39;</code>.</li>
-	<li><code>expression</code> does not contain any leading or trailing spaces.</li>
-	<li>All the tokens in <code>expression</code> are separated by a single space.</li>
-	<li><code>0 &lt;= evalvars.length &lt;= 100</code></li>
-	<li><code>1 &lt;= evalvars[i].length &lt;= 20</code></li>
-	<li><code>evalvars[i]</code> consists of lowercase English letters.</li>
-	<li><code>evalints.length == evalvars.length</code></li>
-	<li><code>-100 &lt;= evalints[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Parse Lisp Expression](../parse-lisp-expression) (Hard)
-  1. [Basic Calculator III](../basic-calculator-iii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-One way is with a Polynomial class.  For example,
-
-* `Poly:add(this, that)` returns the result of `this + that`.
-* `Poly:sub(this, that)` returns the result of `this - that`.
-* `Poly:mul(this, that)` returns the result of `this * that`.
-* `Poly:evaluate(this, evalmap)` returns the polynomial after replacing all free variables with constants as specified by `evalmap`.
-* `Poly:toList(this)` returns the polynomial in the correct output format.
-
-* `Solution::combine(left, right, symbol)` returns the result of applying the binary operator represented by `symbol` to `left` and `right`.
-* `Solution::make(expr)` makes a new `Poly` represented by either the constant or free variable specified by `expr`.
-* `Solution::parse(expr)` parses an expression into a new `Poly`.
-</details>
diff --git a/problems/basic-calculator-iv/basic_calculator_iv.go b/problems/basic-calculator-iv/basic_calculator_iv.go
deleted file mode 100644
index 58dead005..000000000
--- a/problems/basic-calculator-iv/basic_calculator_iv.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem770
diff --git a/problems/basic-calculator-iv/basic_calculator_iv_test.go b/problems/basic-calculator-iv/basic_calculator_iv_test.go
deleted file mode 100644
index 58dead005..000000000
--- a/problems/basic-calculator-iv/basic_calculator_iv_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem770
diff --git a/problems/basic-calculator/README.md b/problems/basic-calculator/README.md
deleted file mode 100644
index df8bef877..000000000
--- a/problems/basic-calculator/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rectangle-area "Rectangle Area")
-　　　　　　　　　　　　　　　　
-[Next >](../implement-stack-using-queues "Implement Stack using Queues")
-
-## [224. Basic Calculator (Hard)](https://leetcode.com/problems/basic-calculator "基本计算器")
-
-<p>Given a string <code>s</code> representing a valid expression, implement a basic calculator to evaluate it, and return <em>the result of the evaluation</em>.</p>
-
-<p><strong>Note:</strong> You are <strong>not</strong> allowed to use any built-in function which evaluates strings as mathematical expressions, such as <code>eval()</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1 + 1&quot;
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot; 2-1 + 2 &quot;
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(1+(4+5+2)-3)+(6+8)&quot;
-<strong>Output:</strong> 23
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 3 * 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of digits, <code>&#39;+&#39;</code>, <code>&#39;-&#39;</code>, <code>&#39;(&#39;</code>, <code>&#39;)&#39;</code>, and <code>&#39; &#39;</code>.</li>
-	<li><code>s</code> represents a valid expression.</li>
-	<li><code>&#39;+&#39;</code> is <strong>not</strong> used as a unary operation (i.e., <code>&quot;+1&quot;</code> and <code>&quot;+(2 + 3)&quot;</code> is invalid).</li>
-	<li><code>&#39;-&#39;</code> could be used as a unary operation (i.e., <code>&quot;-1&quot;</code> and <code>&quot;-(2 + 3)&quot;</code> is valid).</li>
-	<li>There will be no two consecutive operators in the input.</li>
-	<li>Every number and running calculation will fit in a signed 32-bit integer.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Evaluate Reverse Polish Notation](../evaluate-reverse-polish-notation) (Medium)
-  1. [Basic Calculator II](../basic-calculator-ii) (Medium)
-  1. [Different Ways to Add Parentheses](../different-ways-to-add-parentheses) (Medium)
-  1. [Expression Add Operators](../expression-add-operators) (Hard)
-  1. [Basic Calculator III](../basic-calculator-iii) (Hard)
diff --git a/problems/basic-calculator/basic_calculator.go b/problems/basic-calculator/basic_calculator.go
deleted file mode 100644
index 439adc00f..000000000
--- a/problems/basic-calculator/basic_calculator.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem224
diff --git a/problems/basic-calculator/basic_calculator_test.go b/problems/basic-calculator/basic_calculator_test.go
deleted file mode 100644
index 439adc00f..000000000
--- a/problems/basic-calculator/basic_calculator_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem224
diff --git a/problems/battleships-in-a-board/README.md b/problems/battleships-in-a-board/README.md
deleted file mode 100644
index 0fd2ab0d2..000000000
--- a/problems/battleships-in-a-board/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sentence-screen-fitting "Sentence Screen Fitting")
-　　　　　　　　　　　　　　　　
-[Next >](../strong-password-checker "Strong Password Checker")
-
-## [419. Battleships in a Board (Medium)](https://leetcode.com/problems/battleships-in-a-board "甲板上的战舰")
-
-<p>Given an <code>m x n</code> matrix <code>board</code> where each cell is a battleship <code>&#39;X&#39;</code> or empty <code>&#39;.&#39;</code>, return <em>the number of the <strong>battleships</strong> on</em> <code>board</code>.</p>
-
-<p><strong>Battleships</strong> can only be placed horizontally or vertically on <code>board</code>. In other words, they can only be made of the shape <code>1 x k</code> (<code>1</code> row, <code>k</code> columns) or <code>k x 1</code> (<code>k</code> rows, <code>1</code> column), where <code>k</code> can be of any size. At least one horizontal or vertical cell separates between two battleships (i.e., there are no adjacent battleships).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/10/battelship-grid.jpg" style="width: 333px; height: 333px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;X&quot;,&quot;.&quot;,&quot;.&quot;,&quot;X&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;X&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;X&quot;]]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> board = [[&quot;.&quot;]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == board.length</code></li>
-	<li><code>n == board[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>board[i][j]</code> is either <code>&#39;.&#39;</code> or <code>&#39;X&#39;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you do it in one-pass, using only <code>O(1)</code> extra memory and without modifying the values <code>board</code>?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/battleships-in-a-board/battleships_in_a_board.go b/problems/battleships-in-a-board/battleships_in_a_board.go
deleted file mode 100644
index 686438018..000000000
--- a/problems/battleships-in-a-board/battleships_in_a_board.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem419
diff --git a/problems/battleships-in-a-board/battleships_in_a_board_test.go b/problems/battleships-in-a-board/battleships_in_a_board_test.go
deleted file mode 100644
index 686438018..000000000
--- a/problems/battleships-in-a-board/battleships_in_a_board_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem419
diff --git a/problems/beautiful-arrangement-ii/README.md b/problems/beautiful-arrangement-ii/README.md
deleted file mode 100644
index 2b4e92760..000000000
--- a/problems/beautiful-arrangement-ii/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-sum-iv "Path Sum IV")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-smallest-number-in-multiplication-table "Kth Smallest Number in Multiplication Table")
-
-## [667. Beautiful Arrangement II (Medium)](https://leetcode.com/problems/beautiful-arrangement-ii "优美的排列 II")
-
-<p>Given two integers <code>n</code> and <code>k</code>, construct a list <code>answer</code> that contains <code>n</code> different positive integers ranging from <code>1</code> to <code>n</code> and obeys the following requirement:</p>
-
-<ul>
-	<li>Suppose this list is <code>answer =&nbsp;[a<sub>1</sub>, a<sub>2</sub>, a<sub>3</sub>, ... , a<sub>n</sub>]</code>, then the list <code>[|a<sub>1</sub> - a<sub>2</sub>|, |a<sub>2</sub> - a<sub>3</sub>|, |a<sub>3</sub> - a<sub>4</sub>|, ... , |a<sub>n-1</sub> - a<sub>n</sub>|]</code> has exactly <code>k</code> distinct integers.</li>
-</ul>
-
-<p>Return <em>the list</em> <code>answer</code>. If there multiple valid answers, return <strong>any of them</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 1
-<strong>Output:</strong> [1,2,3]
-Explanation: The [1,2,3] has three different positive integers ranging from 1 to 3, and the [1,1] has exactly 1 distinct integer: 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 2
-<strong>Output:</strong> [1,3,2]
-Explanation: The [1,3,2] has three different positive integers ranging from 1 to 3, and the [2,1] has exactly 2 distinct integers: 1 and 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt; n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Beautiful Arrangement](../beautiful-arrangement) (Medium)
diff --git a/problems/beautiful-arrangement-ii/beautiful_arrangement_ii.go b/problems/beautiful-arrangement-ii/beautiful_arrangement_ii.go
deleted file mode 100644
index 940153f99..000000000
--- a/problems/beautiful-arrangement-ii/beautiful_arrangement_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem667
diff --git a/problems/beautiful-arrangement-ii/beautiful_arrangement_ii_test.go b/problems/beautiful-arrangement-ii/beautiful_arrangement_ii_test.go
deleted file mode 100644
index 940153f99..000000000
--- a/problems/beautiful-arrangement-ii/beautiful_arrangement_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem667
diff --git a/problems/beautiful-arrangement/README.md b/problems/beautiful-arrangement/README.md
deleted file mode 100644
index 054a56581..000000000
--- a/problems/beautiful-arrangement/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../contiguous-array "Contiguous Array")
-　　　　　　　　　　　　　　　　
-[Next >](../word-abbreviation "Word Abbreviation")
-
-## [526. Beautiful Arrangement (Medium)](https://leetcode.com/problems/beautiful-arrangement "优美的排列")
-
-<p>Suppose you have <code>n</code> integers labeled <code>1</code> through <code>n</code>. A permutation of those <code>n</code> integers <code>perm</code> (<strong>1-indexed</strong>) is considered a <strong>beautiful arrangement</strong> if for every <code>i</code> (<code>1 &lt;= i &lt;= n</code>), <strong>either</strong> of the following is true:</p>
-
-<ul>
-	<li><code>perm[i]</code> is divisible by <code>i</code>.</li>
-	<li><code>i</code> is divisible by <code>perm[i]</code>.</li>
-</ul>
-
-<p>Given an integer <code>n</code>, return <em>the <strong>number</strong> of the <strong>beautiful arrangements</strong> that you can construct</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 2
-<b>Explanation:</b> 
-The first beautiful arrangement is [1,2]:
-    - perm[1] = 1 is divisible by i = 1
-    - perm[2] = 2 is divisible by i = 2
-The second beautiful arrangement is [2,1]:
-    - perm[1] = 2 is divisible by i = 1
-    - i = 2 is divisible by perm[2] = 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 15</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Similar Questions
-  1. [Beautiful Arrangement II](../beautiful-arrangement-ii) (Medium)
diff --git a/problems/beautiful-arrangement/beautiful_arrangement.go b/problems/beautiful-arrangement/beautiful_arrangement.go
deleted file mode 100644
index bc0f0207c..000000000
--- a/problems/beautiful-arrangement/beautiful_arrangement.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem526
diff --git a/problems/beautiful-arrangement/beautiful_arrangement_test.go b/problems/beautiful-arrangement/beautiful_arrangement_test.go
deleted file mode 100644
index bc0f0207c..000000000
--- a/problems/beautiful-arrangement/beautiful_arrangement_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem526
diff --git a/problems/beautiful-array/README.md b/problems/beautiful-array/README.md
deleted file mode 100644
index 7d27947ad..000000000
--- a/problems/beautiful-array/README.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-falling-path-sum "Minimum Falling Path Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-recent-calls "Number of Recent Calls")
-
-## [932. Beautiful Array (Medium)](https://leetcode.com/problems/beautiful-array "漂亮数组")
-
-<p>An array <code>nums</code> of length <code>n</code> is <strong>beautiful</strong> if:</p>
-
-<ul>
-	<li><code>nums</code> is a permutation of the integers in the range <code>[1, n]</code>.</li>
-	<li>For every <code>0 &lt;= i &lt; j &lt; n</code>, there is no index <code>k</code> with <code>i &lt; k &lt; j</code> where <code>2 * nums[k] == nums[i] + nums[j]</code>.</li>
-</ul>
-
-<p>Given the integer <code>n</code>, return <em>any <strong>beautiful</strong> array </em><code>nums</code><em> of length </em><code>n</code>. There will be at least one valid answer for the given <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 4
-<strong>Output:</strong> [2,1,4,3]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 5
-<strong>Output:</strong> [3,1,2,5,4]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
diff --git a/problems/beautiful-array/beautiful_array.go b/problems/beautiful-array/beautiful_array.go
deleted file mode 100644
index 852504bce..000000000
--- a/problems/beautiful-array/beautiful_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem932
diff --git a/problems/beautiful-array/beautiful_array_test.go b/problems/beautiful-array/beautiful_array_test.go
deleted file mode 100644
index 852504bce..000000000
--- a/problems/beautiful-array/beautiful_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem932
diff --git a/problems/before-and-after-puzzle/README.md b/problems/before-and-after-puzzle/README.md
deleted file mode 100644
index 24706b19c..000000000
--- a/problems/before-and-after-puzzle/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-substrings-with-only-one-distinct-letter "Count Substrings with Only One Distinct Letter")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-distance-to-target-color "Shortest Distance to Target Color")
-
-## [1181. Before and After Puzzle (Medium)](https://leetcode.com/problems/before-and-after-puzzle "前后拼接")
-
-<p>Given a list of <code>phrases</code>, generate a list of&nbsp;Before and After puzzles.</p>
-
-<p>A <em>phrase</em> is a string that consists of lowercase English letters and spaces only. No space appears in the start or the end of a phrase. There are&nbsp;no consecutive spaces&nbsp;in a phrase.</p>
-
-<p><em>Before and After&nbsp;puzzles</em> are phrases that are formed by merging&nbsp;two phrases where the <strong>last&nbsp;word of the first&nbsp;phrase</strong> is the same as the <strong>first word of the second phrase</strong>.</p>
-
-<p>Return the&nbsp;Before and After&nbsp;puzzles that can be formed by every two phrases&nbsp;<code>phrases[i]</code>&nbsp;and&nbsp;<code>phrases[j]</code>&nbsp;where&nbsp;<code>i != j</code>. Note that the order of matching two phrases matters, we want to consider both orders.</p>
-
-<p>You should return a list of&nbsp;<strong>distinct</strong>&nbsp;strings <strong>sorted&nbsp;lexicographically</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> phrases = [&quot;writing code&quot;,&quot;code rocks&quot;]
-<strong>Output:</strong> [&quot;writing code rocks&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> phrases = [&quot;mission statement&quot;,
-                  &quot;a quick bite to eat&quot;,
-&nbsp;                 &quot;a chip off the old block&quot;,
-&nbsp;                 &quot;chocolate bar&quot;,
-&nbsp;                 &quot;mission impossible&quot;,
-&nbsp;                 &quot;a man on a mission&quot;,
-&nbsp;                 &quot;block party&quot;,
-&nbsp;                 &quot;eat my words&quot;,
-&nbsp;                 &quot;bar of soap&quot;]
-<strong>Output:</strong> [&quot;a chip off the old block party&quot;,
-&nbsp;        &quot;a man on a mission impossible&quot;,
-&nbsp;        &quot;a man on a mission statement&quot;,
-&nbsp;        &quot;a quick bite to eat my words&quot;,
-         &quot;chocolate bar of soap&quot;]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> phrases = [&quot;a&quot;,&quot;b&quot;,&quot;a&quot;]
-<strong>Output:</strong> [&quot;a&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= phrases.length &lt;= 100</code></li>
-	<li><code>1 &lt;= phrases[i].length &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if you check every pair of strings (bruteforce)?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For every two strings, check if they can form a puzzle by comparing their last and first words.
-</details>
diff --git a/problems/best-meeting-point/README.md b/problems/best-meeting-point/README.md
deleted file mode 100644
index f513e9738..000000000
--- a/problems/best-meeting-point/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-median-from-data-stream "Find Median from Data Stream")
-　　　　　　　　　　　　　　　　
-[Next >](../serialize-and-deserialize-binary-tree "Serialize and Deserialize Binary Tree")
-
-## [296. Best Meeting Point (Hard)](https://leetcode.com/problems/best-meeting-point "最佳的碰头地点")
-
-<p>A group of two or more people wants to meet and minimize the total travel distance. You are given a 2D grid of values 0 or 1, where each 1 marks the home of someone in the group. The distance is calculated using <a href="http://en.wikipedia.org/wiki/Taxicab_geometry" target="_blank">Manhattan Distance</a>, where distance(p1, p2) = <code>|p2.x - p1.x| + |p2.y - p1.y|</code>.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-
-1 - 0 - 0 - 0 - 1
-|   |   |   |   |
-0 - 0 - 0 - 0 - 0
-|   |   |   |   |
-0 - 0 - 1 - 0 - 0
-
-<strong>Output: 6 
-
-Explanation: </strong>Given three people living at <code>(0,0)</code>, <code>(0,4)</code>, and <code>(2,2)</code>:
-&nbsp;            The point <code>(0,2)</code> is an ideal meeting point, as the total travel distance 
-&nbsp;            of 2+2+2=6 is minimal. So return 6.</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Shortest Distance from All Buildings](../shortest-distance-from-all-buildings) (Hard)
-  1. [Minimum Moves to Equal Array Elements II](../minimum-moves-to-equal-array-elements-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to solve it in one dimension first. How can this solution apply to the two dimension case?
-</details>
diff --git a/problems/best-meeting-point/best_meeting_point.go b/problems/best-meeting-point/best_meeting_point.go
deleted file mode 100644
index b562cd74e..000000000
--- a/problems/best-meeting-point/best_meeting_point.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem296
diff --git a/problems/best-meeting-point/best_meeting_point_test.go b/problems/best-meeting-point/best_meeting_point_test.go
deleted file mode 100644
index b562cd74e..000000000
--- a/problems/best-meeting-point/best_meeting_point_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem296
diff --git a/problems/best-position-for-a-service-centre/README.md b/problems/best-position-for-a-service-centre/README.md
deleted file mode 100644
index 224671215..000000000
--- a/problems/best-position-for-a-service-centre/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-with-maximum-probability "Path with Maximum Probability")
-　　　　　　　　　　　　　　　　
-[Next >](../move-sub-tree-of-n-ary-tree "Move Sub-Tree of N-Ary Tree")
-
-## [1515. Best Position for a Service Centre (Hard)](https://leetcode.com/problems/best-position-for-a-service-centre "服务中心的最佳位置")
-
-<p>A delivery company wants to build a new service center in a new city. The company knows the positions of all the customers in this city on a 2D-Map and wants to build the new center in a position such that <strong>the sum of the euclidean distances to all customers is minimum</strong>.</p>
-
-<p>Given an array <code>positions</code> where <code>positions[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> is the position of the <code>ith</code> customer on the map, return <em>the minimum sum of the euclidean distances</em> to all customers.</p>
-
-<p>In other words, you need to choose the position of the service center <code>[x<sub>centre</sub>, y<sub>centre</sub>]</code> such that the following formula is minimized:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/25/q4_edited.jpg" />
-<p>Answers within <code>10<sup>-5</sup></code> of the actual value will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/25/q4_e1.jpg" style="width: 377px; height: 362px;" />
-<pre>
-<strong>Input:</strong> positions = [[0,1],[1,0],[1,2],[2,1]]
-<strong>Output:</strong> 4.00000
-<strong>Explanation:</strong> As shown, you can see that choosing [x<sub>centre</sub>, y<sub>centre</sub>] = [1, 1] will make the distance to each customer = 1, the sum of all distances is 4 which is the minimum possible we can achieve.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/25/q4_e3.jpg" style="width: 419px; height: 419px;" />
-<pre>
-<strong>Input:</strong> positions = [[1,1],[3,3]]
-<strong>Output:</strong> 2.82843
-<strong>Explanation:</strong> The minimum possible sum of distances = sqrt(2) + sqrt(2) = 2.82843
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= positions.length &lt;= 50</code></li>
-	<li><code>positions[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The problem can be reworded as, giving a set of points on a 2d-plane, return the geometric median.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop over each triplet of points (positions[i], positions[j], positions[k]) where i < j < k, get the centre of the circle which goes throw the 3 points, check if all other points lie in this circle.
-</details>
diff --git a/problems/best-sightseeing-pair/README.md b/problems/best-sightseeing-pair/README.md
deleted file mode 100644
index 2889a419e..000000000
--- a/problems/best-sightseeing-pair/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partition-array-into-three-parts-with-equal-sum "Partition Array Into Three Parts With Equal Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-integer-divisible-by-k "Smallest Integer Divisible by K")
-
-## [1014. Best Sightseeing Pair (Medium)](https://leetcode.com/problems/best-sightseeing-pair "最佳观光组合")
-
-<p>You are given an integer array <code>values</code> where values[i] represents the value of the <code>i<sup>th</sup></code> sightseeing spot. Two sightseeing spots <code>i</code> and <code>j</code> have a <strong>distance</strong> <code>j - i</code> between them.</p>
-
-<p>The score of a pair (<code>i &lt; j</code>) of sightseeing spots is <code>values[i] + values[j] + i - j</code>: the sum of the values of the sightseeing spots, minus the distance between them.</p>
-
-<p>Return <em>the maximum score of a pair of sightseeing spots</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> values = [8,1,5,2,6]
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> i = 0, j = 2, values[i] + values[j] + i - j = 8 + 5 + 0 - 2 = 11
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> values = [1,2]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= values.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= values[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you tell the best sightseeing spot in one pass (ie. as you iterate over the input?)  What should we store or keep track of as we iterate to do this?
-</details>
diff --git a/problems/best-sightseeing-pair/best_sightseeing_pair.go b/problems/best-sightseeing-pair/best_sightseeing_pair.go
deleted file mode 100644
index bad3da607..000000000
--- a/problems/best-sightseeing-pair/best_sightseeing_pair.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem1014
-
-func maxScoreSightseeingPair(A []int) int {
-	a := A[0] // a is A[i]+i
-	res := 0
-	for j := 1; j < len(A); j++ {
-		res = max(res, a+A[j]-j)
-		a = max(a, A[j]+j)
-	}
-	return res
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/best-team-with-no-conflicts/README.md b/problems/best-team-with-no-conflicts/README.md
deleted file mode 100644
index 945122c01..000000000
--- a/problems/best-team-with-no-conflicts/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lexicographically-smallest-string-after-applying-operations "Lexicographically Smallest String After Applying Operations")
-　　　　　　　　　　　　　　　　
-[Next >](../graph-connectivity-with-threshold "Graph Connectivity With Threshold")
-
-## [1626. Best Team With No Conflicts (Medium)](https://leetcode.com/problems/best-team-with-no-conflicts "无矛盾的最佳球队")
-
-<p>You are the manager of a basketball team. For the upcoming tournament, you want to choose the team with the highest overall score. The score of the team is the <strong>sum</strong> of scores of all the players in the team.</p>
-
-<p>However, the basketball team is not allowed to have <strong>conflicts</strong>. A <strong>conflict</strong> exists if a younger player has a <strong>strictly higher</strong> score than an older player. A conflict does <strong>not</strong> occur between players of the same age.</p>
-
-<p>Given two lists, <code>scores</code> and <code>ages</code>, where each <code>scores[i]</code> and <code>ages[i]</code> represents the score and age of the <code>i<sup>th</sup></code> player, respectively, return <em>the highest overall score of all possible basketball teams</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> scores = [1,3,5,10,15], ages = [1,2,3,4,5]
-<strong>Output:</strong> 34
-<strong>Explanation:</strong>&nbsp;You can choose all the players.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> scores = [4,5,6,5], ages = [2,1,2,1]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong>&nbsp;It is best to choose the last 3 players. Notice that you are allowed to choose multiple people of the same age.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> scores = [1,2,3,5], ages = [8,9,10,1]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong>&nbsp;It is best to choose the first 3 players. 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= scores.length, ages.length &lt;= 1000</code></li>
-	<li><code>scores.length == ages.length</code></li>
-	<li><code>1 &lt;= scores[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= ages[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First, sort players by age and break ties by their score. You can now consider the players from left to right.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you choose to include a player, you must only choose players with at least that score later on.
-</details>
diff --git a/problems/best-time-to-buy-and-sell-stock-ii/README.md b/problems/best-time-to-buy-and-sell-stock-ii/README.md
deleted file mode 100644
index 2bd861814..000000000
--- a/problems/best-time-to-buy-and-sell-stock-ii/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-time-to-buy-and-sell-stock "Best Time to Buy and Sell Stock")
-　　　　　　　　　　　　　　　　
-[Next >](../best-time-to-buy-and-sell-stock-iii "Best Time to Buy and Sell Stock III")
-
-## [122. Best Time to Buy and Sell Stock II (Medium)](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii "买卖股票的最佳时机 II")
-
-<p>You are given an integer array <code>prices</code> where <code>prices[i]</code> is the price of a given stock on the <code>i<sup>th</sup></code> day.</p>
-
-<p>On each day, you may decide to buy and/or sell the stock. You can only hold <strong>at most one</strong> share of the stock at any time. However, you can buy it then immediately sell it on the <strong>same day</strong>.</p>
-
-<p>Find and return <em>the <strong>maximum</strong> profit you can achieve</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [7,1,5,3,6,4]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> Buy on day 2 (price = 1) and sell on day 3 (price = 5), profit = 5-1 = 4.
-Then buy on day 4 (price = 3) and sell on day 5 (price = 6), profit = 6-3 = 3.
-Total profit is 4 + 3 = 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [1,2,3,4,5]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.
-Total profit is 4.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [7,6,4,3,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no way to make a positive profit, so we never buy the stock to achieve the maximum profit of 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= prices.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= prices[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Best Time to Buy and Sell Stock](../best-time-to-buy-and-sell-stock) (Easy)
-  1. [Best Time to Buy and Sell Stock III](../best-time-to-buy-and-sell-stock-iii) (Hard)
-  1. [Best Time to Buy and Sell Stock IV](../best-time-to-buy-and-sell-stock-iv) (Hard)
-  1. [Best Time to Buy and Sell Stock with Cooldown](../best-time-to-buy-and-sell-stock-with-cooldown) (Medium)
-  1. [Best Time to Buy and Sell Stock with Transaction Fee](../best-time-to-buy-and-sell-stock-with-transaction-fee) (Medium)
diff --git a/problems/best-time-to-buy-and-sell-stock-ii/best_time_to_buy_and_sell_stock_ii.go b/problems/best-time-to-buy-and-sell-stock-ii/best_time_to_buy_and_sell_stock_ii.go
deleted file mode 100644
index 7260b3177..000000000
--- a/problems/best-time-to-buy-and-sell-stock-ii/best_time_to_buy_and_sell_stock_ii.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package problem122
-
-func maxProfit(prices []int) int {
-	maxProfit := 0
-	for i, p := range prices {
-		if i > 0 && p > prices[i-1] {
-			maxProfit += p - prices[i-1]
-		}
-	}
-	return maxProfit
-}
diff --git a/problems/best-time-to-buy-and-sell-stock-ii/best_time_to_buy_and_sell_stock_ii_test.go b/problems/best-time-to-buy-and-sell-stock-ii/best_time_to_buy_and_sell_stock_ii_test.go
deleted file mode 100644
index ce9cfbb4e..000000000
--- a/problems/best-time-to-buy-and-sell-stock-ii/best_time_to_buy_and_sell_stock_ii_test.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package problem122
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMaxProfit(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{7, 1, 5, 3, 6, 4},
-			want: 7,
-		},
-		{
-			in:   []int{1, 2, 3, 4, 5},
-			want: 4,
-		},
-		{
-			in:   []int{7, 6, 4, 3, 1},
-			want: 0,
-		},
-	}
-
-	for _, tt := range tests {
-		got := maxProfit(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/best-time-to-buy-and-sell-stock-iii/README.md b/problems/best-time-to-buy-and-sell-stock-iii/README.md
deleted file mode 100644
index aed420db4..000000000
--- a/problems/best-time-to-buy-and-sell-stock-iii/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-time-to-buy-and-sell-stock-ii "Best Time to Buy and Sell Stock II")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-maximum-path-sum "Binary Tree Maximum Path Sum")
-
-## [123. Best Time to Buy and Sell Stock III (Hard)](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii "买卖股票的最佳时机 III")
-
-<p>You are given an array <code>prices</code> where <code>prices[i]</code> is the price of a given stock on the <code>i<sup>th</sup></code> day.</p>
-
-<p>Find the maximum profit you can achieve. You may complete <strong>at most two transactions</strong>.</p>
-
-<p><strong>Note:</strong> You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [3,3,5,0,0,3,1,4]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Buy on day 4 (price = 0) and sell on day 6 (price = 3), profit = 3-0 = 3.
-Then buy on day 7 (price = 1) and sell on day 8 (price = 4), profit = 4-1 = 3.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [1,2,3,4,5]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.
-Note that you cannot buy on day 1, buy on day 2 and sell them later, as you are engaging multiple transactions at the same time. You must sell before buying again.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [7,6,4,3,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> In this case, no transaction is done, i.e. max profit = 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= prices.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= prices[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Best Time to Buy and Sell Stock](../best-time-to-buy-and-sell-stock) (Easy)
-  1. [Best Time to Buy and Sell Stock II](../best-time-to-buy-and-sell-stock-ii) (Medium)
-  1. [Best Time to Buy and Sell Stock IV](../best-time-to-buy-and-sell-stock-iv) (Hard)
-  1. [Maximum Sum of 3 Non-Overlapping Subarrays](../maximum-sum-of-3-non-overlapping-subarrays) (Hard)
diff --git a/problems/best-time-to-buy-and-sell-stock-iii/best_time_to_buy_and_sell_stock_iii.go b/problems/best-time-to-buy-and-sell-stock-iii/best_time_to_buy_and_sell_stock_iii.go
deleted file mode 100644
index 9575f65f6..000000000
--- a/problems/best-time-to-buy-and-sell-stock-iii/best_time_to_buy_and_sell_stock_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem123
diff --git a/problems/best-time-to-buy-and-sell-stock-iii/best_time_to_buy_and_sell_stock_iii_test.go b/problems/best-time-to-buy-and-sell-stock-iii/best_time_to_buy_and_sell_stock_iii_test.go
deleted file mode 100644
index 9575f65f6..000000000
--- a/problems/best-time-to-buy-and-sell-stock-iii/best_time_to_buy_and_sell_stock_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem123
diff --git a/problems/best-time-to-buy-and-sell-stock-iv/README.md b/problems/best-time-to-buy-and-sell-stock-iv/README.md
deleted file mode 100644
index 6bba064fd..000000000
--- a/problems/best-time-to-buy-and-sell-stock-iv/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../repeated-dna-sequences "Repeated DNA Sequences")
-　　　　　　　　　　　　　　　　
-[Next >](../rotate-array "Rotate Array")
-
-## [188. Best Time to Buy and Sell Stock IV (Hard)](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv "买卖股票的最佳时机 IV")
-
-<p>You are given an integer array <code>prices</code> where <code>prices[i]</code> is the price of a given stock on the <code>i<sup>th</sup></code> day, and an integer <code>k</code>.</p>
-
-<p>Find the maximum profit you can achieve. You may complete at most <code>k</code> transactions.</p>
-
-<p><strong>Note:</strong> You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 2, prices = [2,4,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Buy on day 1 (price = 2) and sell on day 2 (price = 4), profit = 4-2 = 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 2, prices = [3,2,6,5,0,3]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> Buy on day 2 (price = 2) and sell on day 3 (price = 6), profit = 6-2 = 4. Then buy on day 5 (price = 0) and sell on day 6 (price = 3), profit = 3-0 = 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= k &lt;= 100</code></li>
-	<li><code>0 &lt;= prices.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= prices[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Best Time to Buy and Sell Stock](../best-time-to-buy-and-sell-stock) (Easy)
-  1. [Best Time to Buy and Sell Stock II](../best-time-to-buy-and-sell-stock-ii) (Medium)
-  1. [Best Time to Buy and Sell Stock III](../best-time-to-buy-and-sell-stock-iii) (Hard)
diff --git a/problems/best-time-to-buy-and-sell-stock-iv/best_time_to_buy_and_sell_stock_iv.go b/problems/best-time-to-buy-and-sell-stock-iv/best_time_to_buy_and_sell_stock_iv.go
deleted file mode 100644
index 1da2acbdd..000000000
--- a/problems/best-time-to-buy-and-sell-stock-iv/best_time_to_buy_and_sell_stock_iv.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem188
diff --git a/problems/best-time-to-buy-and-sell-stock-iv/best_time_to_buy_and_sell_stock_iv_test.go b/problems/best-time-to-buy-and-sell-stock-iv/best_time_to_buy_and_sell_stock_iv_test.go
deleted file mode 100644
index 1da2acbdd..000000000
--- a/problems/best-time-to-buy-and-sell-stock-iv/best_time_to_buy_and_sell_stock_iv_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem188
diff --git a/problems/best-time-to-buy-and-sell-stock-with-cooldown/README.md b/problems/best-time-to-buy-and-sell-stock-with-cooldown/README.md
deleted file mode 100644
index 1c8c2b76d..000000000
--- a/problems/best-time-to-buy-and-sell-stock-with-cooldown/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-sum-query-2d-mutable "Range Sum Query 2D - Mutable")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-height-trees "Minimum Height Trees")
-
-## [309. Best Time to Buy and Sell Stock with Cooldown (Medium)](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown "最佳买卖股票时机含冷冻期")
-
-<p>You are given an array <code>prices</code> where <code>prices[i]</code> is the price of a given stock on the <code>i<sup>th</sup></code> day.</p>
-
-<p>Find the maximum profit you can achieve. You may complete as many transactions as you like (i.e., buy one and sell one share of the stock multiple times) with the following restrictions:</p>
-
-<ul>
-	<li>After you sell your stock, you cannot buy stock on the next day (i.e., cooldown one day).</li>
-</ul>
-
-<p><strong>Note:</strong> You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [1,2,3,0,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> transactions = [buy, sell, cooldown, buy, sell]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= prices.length &lt;= 5000</code></li>
-	<li><code>0 &lt;= prices[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Best Time to Buy and Sell Stock](../best-time-to-buy-and-sell-stock) (Easy)
-  1. [Best Time to Buy and Sell Stock II](../best-time-to-buy-and-sell-stock-ii) (Medium)
diff --git a/problems/best-time-to-buy-and-sell-stock-with-cooldown/best_time_to_buy_and_sell_stock_with_cooldown.go b/problems/best-time-to-buy-and-sell-stock-with-cooldown/best_time_to_buy_and_sell_stock_with_cooldown.go
deleted file mode 100644
index 3faa85852..000000000
--- a/problems/best-time-to-buy-and-sell-stock-with-cooldown/best_time_to_buy_and_sell_stock_with_cooldown.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem309
diff --git a/problems/best-time-to-buy-and-sell-stock-with-cooldown/best_time_to_buy_and_sell_stock_with_cooldown_test.go b/problems/best-time-to-buy-and-sell-stock-with-cooldown/best_time_to_buy_and_sell_stock_with_cooldown_test.go
deleted file mode 100644
index 3faa85852..000000000
--- a/problems/best-time-to-buy-and-sell-stock-with-cooldown/best_time_to_buy_and_sell_stock_with_cooldown_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem309
diff --git a/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/README.md b/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/README.md
deleted file mode 100644
index 199745595..000000000
--- a/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subarray-product-less-than-k "Subarray Product Less Than K")
-　　　　　　　　　　　　　　　　
-[Next >](../range-module "Range Module")
-
-## [714. Best Time to Buy and Sell Stock with Transaction Fee (Medium)](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-transaction-fee "买卖股票的最佳时机含手续费")
-
-<p>You are given an array <code>prices</code> where <code>prices[i]</code> is the price of a given stock on the <code>i<sup>th</sup></code> day, and an integer <code>fee</code> representing a transaction fee.</p>
-
-<p>Find the maximum profit you can achieve. You may complete as many transactions as you like, but you need to pay the transaction fee for each transaction.</p>
-
-<p><strong>Note:</strong> You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [1,3,2,8,4,9], fee = 2
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> The maximum profit can be achieved by:
-- Buying at prices[0] = 1
-- Selling at prices[3] = 8
-- Buying at prices[4] = 4
-- Selling at prices[5] = 9
-The total profit is ((8 - 1) - 2) + ((9 - 4) - 2) = 8.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [1,3,7,5,10,3], fee = 3
-<strong>Output:</strong> 6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= prices.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= prices[i] &lt; 5 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= fee &lt; 5 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Best Time to Buy and Sell Stock II](../best-time-to-buy-and-sell-stock-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider the first K stock prices.  At the end, the only legal states are that you don't own a share of stock, or that you do.  Calculate the most profit you could have under each of these two cases.
-</details>
diff --git a/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/best_time_to_buy_and_sell_stock_with_transaction_fee.go b/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/best_time_to_buy_and_sell_stock_with_transaction_fee.go
deleted file mode 100644
index 8a1fc1d4c..000000000
--- a/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/best_time_to_buy_and_sell_stock_with_transaction_fee.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem714
diff --git a/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/best_time_to_buy_and_sell_stock_with_transaction_fee_test.go b/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/best_time_to_buy_and_sell_stock_with_transaction_fee_test.go
deleted file mode 100644
index 8a1fc1d4c..000000000
--- a/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/best_time_to_buy_and_sell_stock_with_transaction_fee_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem714
diff --git a/problems/best-time-to-buy-and-sell-stock/README.md b/problems/best-time-to-buy-and-sell-stock/README.md
deleted file mode 100644
index f421fa34b..000000000
--- a/problems/best-time-to-buy-and-sell-stock/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../triangle "Triangle")
-　　　　　　　　　　　　　　　　
-[Next >](../best-time-to-buy-and-sell-stock-ii "Best Time to Buy and Sell Stock II")
-
-## [121. Best Time to Buy and Sell Stock (Easy)](https://leetcode.com/problems/best-time-to-buy-and-sell-stock "买卖股票的最佳时机")
-
-<p>You are given an array <code>prices</code> where <code>prices[i]</code> is the price of a given stock on the <code>i<sup>th</sup></code> day.</p>
-
-<p>You want to maximize your profit by choosing a <strong>single day</strong> to buy one stock and choosing a <strong>different day in the future</strong> to sell that stock.</p>
-
-<p>Return <em>the maximum profit you can achieve from this transaction</em>. If you cannot achieve any profit, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [7,1,5,3,6,4]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
-Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [7,6,4,3,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> In this case, no transactions are done and the max profit = 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= prices.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= prices[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Maximum Subarray](../maximum-subarray) (Easy)
-  1. [Best Time to Buy and Sell Stock II](../best-time-to-buy-and-sell-stock-ii) (Medium)
-  1. [Best Time to Buy and Sell Stock III](../best-time-to-buy-and-sell-stock-iii) (Hard)
-  1. [Best Time to Buy and Sell Stock IV](../best-time-to-buy-and-sell-stock-iv) (Hard)
-  1. [Best Time to Buy and Sell Stock with Cooldown](../best-time-to-buy-and-sell-stock-with-cooldown) (Medium)
diff --git a/problems/best-time-to-buy-and-sell-stock/best_time_to_buy_and_sell_stock.go b/problems/best-time-to-buy-and-sell-stock/best_time_to_buy_and_sell_stock.go
deleted file mode 100644
index fb2cd65fe..000000000
--- a/problems/best-time-to-buy-and-sell-stock/best_time_to_buy_and_sell_stock.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem121
-
-func maxProfit(prices []int) int {
-	ans, min := 0, 0
-	for i, v := range prices {
-		if v < prices[min] {
-			min = i
-		} else if v-prices[min] > ans {
-			ans = v - prices[min]
-		}
-	}
-	return ans
-}
diff --git a/problems/best-time-to-buy-and-sell-stock/best_time_to_buy_and_sell_stock_test.go b/problems/best-time-to-buy-and-sell-stock/best_time_to_buy_and_sell_stock_test.go
deleted file mode 100644
index 6f7bb2251..000000000
--- a/problems/best-time-to-buy-and-sell-stock/best_time_to_buy_and_sell_stock_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem121
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMaxProfit(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{7, 1, 5, 3, 6, 4},
-			want: 5,
-		},
-		{
-			in:   []int{7, 6, 4, 3, 1},
-			want: 0,
-		},
-		{
-			in:   []int{1, 1, 1, 1, 1},
-			want: 0,
-		},
-		{
-			in:   []int{},
-			want: 0,
-		},
-	}
-	for _, tt := range tests {
-		got := maxProfit(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/big-countries/README.md b/problems/big-countries/README.md
deleted file mode 100644
index ff5363393..000000000
--- a/problems/big-countries/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-harmonious-subsequence "Longest Harmonious Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../classes-more-than-5-students "Classes More Than 5 Students")
-
-## [595. Big Countries (Easy)](https://leetcode.com/problems/big-countries "大的国家")
-
-<p>There is a table <code>World</code></p>
-
-<pre>
-+-----------------+------------+------------+--------------+---------------+
-| name            | continent  | area       | population   | gdp           |
-+-----------------+------------+------------+--------------+---------------+
-| Afghanistan     | Asia       | 652230     | 25500100     | 20343000      |
-| Albania         | Europe     | 28748      | 2831741      | 12960000      |
-| Algeria         | Africa     | 2381741    | 37100000     | 188681000     |
-| Andorra         | Europe     | 468        | 78115        | 3712000       |
-| Angola          | Africa     | 1246700    | 20609294     | 100990000     |
-+-----------------+------------+------------+--------------+---------------+
-</pre>
-
-<p>A country is big if it has an area of bigger than 3 million square km or a population of more than 25 million.</p>
-
-<p>Write a SQL solution to output big countries&#39; name, population and area.</p>
-
-<p>For example, according to the above table, we should output:</p>
-
-<pre>
-+--------------+-------------+--------------+
-| name         | population  | area         |
-+--------------+-------------+--------------+
-| Afghanistan  | 25500100    | 652230       |
-| Algeria      | 37100000    | 2381741      |
-+--------------+-------------+--------------+
-</pre>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/big-countries/big_countries.sql b/problems/big-countries/big_countries.sql
deleted file mode 100644
index bd4c7cee4..000000000
--- a/problems/big-countries/big_countries.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT
-  `name`,
-  `population`,
-  `area`
-FROM
-  `World`
-WHERE
-  `area` > 3000000
-  OR `population` > 25000000;
diff --git a/problems/big-countries/mysql_schemas.sql b/problems/big-countries/mysql_schemas.sql
deleted file mode 100644
index 44994d550..000000000
--- a/problems/big-countries/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists World (name varchar(255), continent varchar(255), area int, population int, gdp int);
-Truncate table World;
-insert into World (name, continent, area, population, gdp) values ('Afghanistan', 'Asia', '652230', '25500100', '20343000000');
-insert into World (name, continent, area, population, gdp) values ('Albania', 'Europe', '28748', '2831741', '12960000000');
-insert into World (name, continent, area, population, gdp) values ('Algeria', 'Africa', '2381741', '37100000', '188681000000');
-insert into World (name, continent, area, population, gdp) values ('Andorra', 'Europe', '468', '78115', '3712000000');
-insert into World (name, continent, area, population, gdp) values ('Angola', 'Africa', '1246700', '20609294', '100990000000');
diff --git a/problems/biggest-single-number/README.md b/problems/biggest-single-number/README.md
deleted file mode 100644
index bb71e7128..000000000
--- a/problems/biggest-single-number/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../students-report-by-geography "Students Report By Geography")
-　　　　　　　　　　　　　　　　
-[Next >](../not-boring-movies "Not Boring Movies")
-
-## [619. Biggest Single Number (Easy)](https://leetcode.com/problems/biggest-single-number "只出现一次的最大数字")
-
-<p>Table <code>my_numbers</code> contains many numbers in column <b>num</b> including duplicated ones.<br />
-Can you write a SQL query to find the biggest number, which only appears once.</p>
-
-<pre>
-+---+
-|num|
-+---+
-| 8 |
-| 8 |
-| 3 |
-| 3 |
-| 1 |
-| 4 |
-| 5 |
-| 6 | 
-</pre>
-For the sample data above, your query should return the following result:
-
-<pre>
-+---+
-|num|
-+---+
-| 6 |
-</pre>
-<b>Note:</b><br />
-If there is no such number, just output <b>null</b>.
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/biggest-single-number/biggest_single_number.sql b/problems/biggest-single-number/biggest_single_number.sql
deleted file mode 100644
index 3e097c7a8..000000000
--- a/problems/biggest-single-number/biggest_single_number.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT MAX(num) AS num
-FROM
-  (SELECT num
-   FROM
-     `my_numbers`
-   GROUP BY num
-   HAVING COUNT(num) = 1) AS t;
diff --git a/problems/biggest-single-number/mysql_schemas.sql b/problems/biggest-single-number/mysql_schemas.sql
deleted file mode 100644
index 99c31bfa5..000000000
--- a/problems/biggest-single-number/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists my_numbers (num int);
-Truncate table my_numbers;
-insert into my_numbers (num) values ('8');
-insert into my_numbers (num) values ('8');
-insert into my_numbers (num) values ('3');
-insert into my_numbers (num) values ('3');
-insert into my_numbers (num) values ('1');
-insert into my_numbers (num) values ('4');
-insert into my_numbers (num) values ('5');
-insert into my_numbers (num) values ('6');
diff --git a/problems/biggest-window-between-visits/README.md b/problems/biggest-window-between-visits/README.md
deleted file mode 100644
index b6e868d16..000000000
--- a/problems/biggest-window-between-visits/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-subarray-length-k "Largest Subarray Length K")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-units-on-a-truck "Maximum Units on a Truck")
-
-## [1709. Biggest Window Between Visits (Medium)](https://leetcode.com/problems/biggest-window-between-visits "访问日期之间最大的空档期")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/biggest-window-between-visits/mysql_schemas.sql b/problems/biggest-window-between-visits/mysql_schemas.sql
deleted file mode 100644
index fba17a19a..000000000
--- a/problems/biggest-window-between-visits/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists UserVisits(user_id int, visit_date date);
-Truncate table UserVisits;
-insert into UserVisits (user_id, visit_date) values ('1', '2020-11-28');
-insert into UserVisits (user_id, visit_date) values ('1', '2020-10-20');
-insert into UserVisits (user_id, visit_date) values ('1', '2020-12-3');
-insert into UserVisits (user_id, visit_date) values ('2', '2020-10-5');
-insert into UserVisits (user_id, visit_date) values ('2', '2020-12-9');
-insert into UserVisits (user_id, visit_date) values ('3', '2020-11-11');
diff --git a/problems/binary-gap/README.md b/problems/binary-gap/README.md
deleted file mode 100644
index ba1264dc0..000000000
--- a/problems/binary-gap/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../transpose-matrix "Transpose Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../reordered-power-of-2 "Reordered Power of 2")
-
-## [868. Binary Gap (Easy)](https://leetcode.com/problems/binary-gap "二进制间距")
-
-<p>Given a positive integer <code>n</code>, find and return <em>the <strong>longest distance</strong> between any two <strong>adjacent</strong> </em><code>1</code><em>&#39;s in the binary representation of </em><code>n</code><em>. If there are no two adjacent </em><code>1</code><em>&#39;s, return </em><code>0</code><em>.</em></p>
-
-<p>Two <code>1</code>&#39;s are <strong>adjacent</strong> if there are only <code>0</code>&#39;s separating them (possibly no <code>0</code>&#39;s). The <b>distance</b> between two <code>1</code>&#39;s is the absolute difference between their bit positions. For example, the two <code>1</code>&#39;s in <code>&quot;1001&quot;</code> have a distance of 3.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 22
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 22 in binary is &quot;10110&quot;.
-The first adjacent pair of 1&#39;s is &quot;<u>1</u>0<u>1</u>10&quot; with a distance of 2.
-The second adjacent pair of 1&#39;s is &quot;10<u>11</u>0&quot; with a distance of 1.
-The answer is the largest of these two distances, which is 2.
-Note that &quot;<u>1</u>01<u>1</u>0&quot; is not a valid pair since there is a 1 separating the two 1&#39;s underlined.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 5 in binary is &quot;101&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 6 in binary is &quot;110&quot;.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 8
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> 8 in binary is &quot;1000&quot;.
-There aren&#39;t any adjacent pairs of 1&#39;s in the binary representation of 8, so we return 0.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/binary-gap/binary_gap.go b/problems/binary-gap/binary_gap.go
deleted file mode 100644
index ae6416e46..000000000
--- a/problems/binary-gap/binary_gap.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem868
diff --git a/problems/binary-gap/binary_gap_test.go b/problems/binary-gap/binary_gap_test.go
deleted file mode 100644
index ae6416e46..000000000
--- a/problems/binary-gap/binary_gap_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem868
diff --git a/problems/binary-number-with-alternating-bits/README.md b/problems/binary-number-with-alternating-bits/README.md
deleted file mode 100644
index c4e00c4fe..000000000
--- a/problems/binary-number-with-alternating-bits/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../top-k-frequent-words "Top K Frequent Words")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-distinct-islands "Number of Distinct Islands")
-
-## [693. Binary Number with Alternating Bits (Easy)](https://leetcode.com/problems/binary-number-with-alternating-bits "交替位二进制数")
-
-<p>Given a positive integer, check whether it has alternating bits: namely, if two adjacent bits will always have different values.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The binary representation of 5 is: 101
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The binary representation of 7 is: 111.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 11
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The binary representation of 11 is: 1011.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Number of 1 Bits](../number-of-1-bits) (Easy)
diff --git a/problems/binary-number-with-alternating-bits/binary_number_with_alternating_bits.go b/problems/binary-number-with-alternating-bits/binary_number_with_alternating_bits.go
deleted file mode 100644
index 749a321d4..000000000
--- a/problems/binary-number-with-alternating-bits/binary_number_with_alternating_bits.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem693
diff --git a/problems/binary-number-with-alternating-bits/binary_number_with_alternating_bits_test.go b/problems/binary-number-with-alternating-bits/binary_number_with_alternating_bits_test.go
deleted file mode 100644
index 749a321d4..000000000
--- a/problems/binary-number-with-alternating-bits/binary_number_with_alternating_bits_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem693
diff --git a/problems/binary-prefix-divisible-by-5/README.md b/problems/binary-prefix-divisible-by-5/README.md
deleted file mode 100644
index 15d409927..000000000
--- a/problems/binary-prefix-divisible-by-5/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-to-base-2 "Convert to Base -2")
-　　　　　　　　　　　　　　　　
-[Next >](../next-greater-node-in-linked-list "Next Greater Node In Linked List")
-
-## [1018. Binary Prefix Divisible By 5 (Easy)](https://leetcode.com/problems/binary-prefix-divisible-by-5 "可被 5 整除的二进制前缀")
-
-<p>You are given a binary array <code>nums</code> (<strong>0-indexed</strong>).</p>
-
-<p>We define <code>x<sub>i</sub></code> as the number whose binary representation is the subarray <code>nums[0..i]</code> (from most-significant-bit to least-significant-bit).</p>
-
-<ul>
-	<li>For example, if <code>nums = [1,0,1]</code>, then <code>x<sub>0</sub> = 1</code>, <code>x<sub>1</sub> = 2</code>, and <code>x<sub>2</sub> = 5</code>.</li>
-</ul>
-
-<p>Return <em>an array of booleans </em><code>answer</code><em> where </em><code>answer[i]</code><em> is </em><code>true</code><em> if </em><code>x<sub>i</sub></code><em> is divisible by </em><code>5</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,1]
-<strong>Output:</strong> [true,false,false]
-<strong>Explanation:</strong> The input numbers in binary are 0, 01, 011; which are 0, 1, and 3 in base-10.
-Only the first number is divisible by 5, so answer[0] is true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1]
-<strong>Output:</strong> [false,false,false]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,1,1,1,1]
-<strong>Output:</strong> [true,false,false,false,true,false]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,0,1]
-<strong>Output:</strong> [false,false,false,false,false]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums[i]</code>&nbsp;is&nbsp;<code>0</code>&nbsp;or&nbsp;<code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If X is the first i digits of the array as a binary number, then 2X + A[i] is the first i+1 digits.
-</details>
diff --git a/problems/binary-prefix-divisible-by-5/binary_prefix_divisible_by_5.go b/problems/binary-prefix-divisible-by-5/binary_prefix_divisible_by_5.go
deleted file mode 100644
index 57fadaa99..000000000
--- a/problems/binary-prefix-divisible-by-5/binary_prefix_divisible_by_5.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem1018
-
-func prefixesDivBy5(A []int) []bool {
-	ans, v := make([]bool, len(A)), 0
-	for i, b := range A {
-		v = (v<<1 + b) % 5
-		ans[i] = v == 0
-	}
-	return ans
-}
diff --git a/problems/binary-prefix-divisible-by-5/binary_prefix_divisible_by_5_test.go b/problems/binary-prefix-divisible-by-5/binary_prefix_divisible_by_5_test.go
deleted file mode 100644
index 113d6d1c8..000000000
--- a/problems/binary-prefix-divisible-by-5/binary_prefix_divisible_by_5_test.go
+++ /dev/null
@@ -1,42 +0,0 @@
-package problem1018
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []bool
-}
-
-func TestPrefixesDivBy5(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{0, 1, 1},
-			want: []bool{true, false, false},
-		},
-		{
-			in:   []int{1, 1, 1},
-			want: []bool{false, false, false},
-		},
-		{
-			in:   []int{0, 1, 1, 1, 1, 1},
-			want: []bool{true, false, false, false, true, false},
-		},
-		{
-			in:   []int{1, 1, 1, 0, 1},
-			want: []bool{false, false, false, false, false},
-		},
-		{
-			in:   []int{1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 1, 0},
-			want: []bool{false, false, true, false, false, false, false, false, false, false, true, true, true, true, true, true, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, false, false, true, false, false, true, false, false, true, true, true, true, true, true, true, false, false, true, false, false, false, false, true, true},
-		},
-	}
-	for _, tt := range tests {
-		got := prefixesDivBy5(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/binary-search-tree-iterator-ii/README.md b/problems/binary-search-tree-iterator-ii/README.md
deleted file mode 100644
index b4e7ca01b..000000000
--- a/problems/binary-search-tree-iterator-ii/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-string-is-transformable-with-substring-sort-operations "Check If String Is Transformable With Substring Sort Operations")
-　　　　　　　　　　　　　　　　
-[Next >](../bank-account-summary-ii "Bank Account Summary II")
-
-## [1586. Binary Search Tree Iterator II (Medium)](https://leetcode.com/problems/binary-search-tree-iterator-ii "二叉搜索树迭代器 II")
-
-
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-  [[Iterator](../../tag/iterator/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The inorder traversal of a BST gives us the elements in a sorted order.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can use a stack to simulate the inorder traversal of the BST.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We can use another stack as a buffer to store numbers returned from calls to next and use this buffer whenever prev is called.
-</details>
diff --git a/problems/binary-search-tree-iterator/README.md b/problems/binary-search-tree-iterator/README.md
deleted file mode 100644
index a76bdfa24..000000000
--- a/problems/binary-search-tree-iterator/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../factorial-trailing-zeroes "Factorial Trailing Zeroes")
-　　　　　　　　　　　　　　　　
-[Next >](../dungeon-game "Dungeon Game")
-
-## [173. Binary Search Tree Iterator (Medium)](https://leetcode.com/problems/binary-search-tree-iterator "二叉搜索树迭代器")
-
-<p>Implement the <code>BSTIterator</code> class that represents an iterator over the <strong><a href="https://en.wikipedia.org/wiki/Tree_traversal#In-order_(LNR)" target="_blank">in-order traversal</a></strong> of a binary search tree (BST):</p>
-
-<ul>
-	<li><code>BSTIterator(TreeNode root)</code> Initializes an object of the <code>BSTIterator</code> class. The <code>root</code> of the BST is given as part of the constructor. The pointer should be initialized to a non-existent number smaller than any element in the BST.</li>
-	<li><code>boolean hasNext()</code> Returns <code>true</code> if there exists a number in the traversal to the right of the pointer, otherwise returns <code>false</code>.</li>
-	<li><code>int next()</code> Moves the pointer to the right, then returns the number at the pointer.</li>
-</ul>
-
-<p>Notice that by initializing the pointer to a non-existent smallest number, the first call to <code>next()</code> will return the smallest element in the BST.</p>
-
-<p>You may assume that <code>next()</code> calls will always be valid. That is, there will be at least a next number in the in-order traversal when <code>next()</code> is called.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/25/bst-tree.png" style="width: 189px; height: 178px;" />
-<pre>
-<strong>Input</strong>
-[&quot;BSTIterator&quot;, &quot;next&quot;, &quot;next&quot;, &quot;hasNext&quot;, &quot;next&quot;, &quot;hasNext&quot;, &quot;next&quot;, &quot;hasNext&quot;, &quot;next&quot;, &quot;hasNext&quot;]
-[[[7, 3, 15, null, null, 9, 20]], [], [], [], [], [], [], [], [], []]
-<strong>Output</strong>
-[null, 3, 7, true, 9, true, 15, true, 20, false]
-
-<strong>Explanation</strong>
-BSTIterator bSTIterator = new BSTIterator([7, 3, 15, null, null, 9, 20]);
-bSTIterator.next();    // return 3
-bSTIterator.next();    // return 7
-bSTIterator.hasNext(); // return True
-bSTIterator.next();    // return 9
-bSTIterator.hasNext(); // return True
-bSTIterator.next();    // return 15
-bSTIterator.hasNext(); // return True
-bSTIterator.next();    // return 20
-bSTIterator.hasNext(); // return False
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>6</sup></code></li>
-	<li>At most <code>10<sup>5</sup></code> calls will be made to <code>hasNext</code>, and <code>next</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>Could you implement <code>next()</code> and <code>hasNext()</code> to run in average <code>O(1)</code> time and use&nbsp;<code>O(h)</code> memory, where <code>h</code> is the height of the tree?</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-  [[Iterator](../../tag/iterator/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Inorder Traversal](../binary-tree-inorder-traversal) (Easy)
-  1. [Flatten 2D Vector](../flatten-2d-vector) (Medium)
-  1. [Zigzag Iterator](../zigzag-iterator) (Medium)
-  1. [Peeking Iterator](../peeking-iterator) (Medium)
-  1. [Inorder Successor in BST](../inorder-successor-in-bst) (Medium)
-  1. [Binary Search Tree Iterator II](../binary-search-tree-iterator-ii) (Medium)
diff --git a/problems/binary-search-tree-iterator/binary_search_tree_iterator.go b/problems/binary-search-tree-iterator/binary_search_tree_iterator.go
deleted file mode 100644
index 7fa1a5358..000000000
--- a/problems/binary-search-tree-iterator/binary_search_tree_iterator.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem173
diff --git a/problems/binary-search-tree-iterator/binary_search_tree_iterator_test.go b/problems/binary-search-tree-iterator/binary_search_tree_iterator_test.go
deleted file mode 100644
index 7fa1a5358..000000000
--- a/problems/binary-search-tree-iterator/binary_search_tree_iterator_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem173
diff --git a/problems/binary-search-tree-to-greater-sum-tree/README.md b/problems/binary-search-tree-to-greater-sum-tree/README.md
deleted file mode 100644
index b0c0f0076..000000000
--- a/problems/binary-search-tree-to-greater-sum-tree/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-boomerang "Valid Boomerang")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-score-triangulation-of-polygon "Minimum Score Triangulation of Polygon")
-
-## [1038. Binary Search Tree to Greater Sum Tree (Medium)](https://leetcode.com/problems/binary-search-tree-to-greater-sum-tree "把二叉搜索树转换为累加树")
-
-<p>Given the <code>root</code> of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum of all keys greater than the original key in BST.</p>
-
-<p>As a reminder, a <em>binary search tree</em> is a tree that satisfies these constraints:</p>
-
-<ul>
-	<li>The left subtree of a node contains only nodes with keys <strong>less than</strong> the node&#39;s key.</li>
-	<li>The right subtree of a node contains only nodes with keys <strong>greater than</strong> the node&#39;s key.</li>
-	<li>Both the left and right subtrees must also be binary search trees.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/05/02/tree.png" style="width: 550px; height: 375px;" />
-<pre>
-<strong>Input:</strong> root = [4,1,6,0,2,5,7,null,null,null,3,null,null,null,8]
-<strong>Output:</strong> [30,36,21,36,35,26,15,null,null,null,33,null,null,null,8]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [0,null,1]
-<strong>Output:</strong> [1,null,1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,0,2]
-<strong>Output:</strong> [3,3,2]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [3,2,4,1]
-<strong>Output:</strong> [7,9,4,10]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 100]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 100</code></li>
-	<li>All the values in the tree are <strong>unique</strong>.</li>
-	<li><code>root</code> is guaranteed to be a valid binary search tree.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 538: <a href="https://leetcode.com/problems/convert-bst-to-greater-tree/" target="_blank">https://leetcode.com/problems/convert-bst-to-greater-tree/</a></p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What traversal method organizes all nodes in sorted order?
-</details>
diff --git a/problems/binary-search/README.md b/problems/binary-search/README.md
deleted file mode 100644
index 782afcd83..000000000
--- a/problems/binary-search/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-largest-element-in-a-stream "Kth Largest Element in a Stream")
-　　　　　　　　　　　　　　　　
-[Next >](../design-hashset "Design HashSet")
-
-## [704. Binary Search (Easy)](https://leetcode.com/problems/binary-search "二分查找")
-
-<p>Given an array of integers <code>nums</code> which is sorted in ascending order, and an integer <code>target</code>, write a function to search <code>target</code> in <code>nums</code>. If <code>target</code> exists, then return its index. Otherwise, return <code>-1</code>.</p>
-
-<p>You must write an algorithm with <code>O(log n)</code> runtime complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,0,3,5,9,12], target = 9
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> 9 exists in nums and its index is 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,0,3,5,9,12], target = 2
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> 2 does not exist in nums so return -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt; nums[i], target &lt; 10<sup>4</sup></code></li>
-	<li>All the integers in <code>nums</code> are <strong>unique</strong>.</li>
-	<li><code>nums</code> is sorted in ascending order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Search in a Sorted Array of Unknown Size](../search-in-a-sorted-array-of-unknown-size) (Medium)
diff --git a/problems/binary-search/binary_search.go b/problems/binary-search/binary_search.go
deleted file mode 100644
index 9a16a73fc..000000000
--- a/problems/binary-search/binary_search.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem704
diff --git a/problems/binary-search/binary_search_test.go b/problems/binary-search/binary_search_test.go
deleted file mode 100644
index 9a16a73fc..000000000
--- a/problems/binary-search/binary_search_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem704
diff --git a/problems/binary-searchable-numbers-in-an-unsorted-array/README.md b/problems/binary-searchable-numbers-in-an-unsorted-array/README.md
deleted file mode 100644
index 6bebaaf0d..000000000
--- a/problems/binary-searchable-numbers-in-an-unsorted-array/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../employees-with-missing-information "Employees With Missing Information")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-strings-that-appear-as-substrings-in-word "Number of Strings That Appear as Substrings in Word")
-
-## [1966. Binary Searchable Numbers in an Unsorted Array (Medium)](https://leetcode.com/problems/binary-searchable-numbers-in-an-unsorted-array "未排序数组中的可被二分搜索的数")
-
-
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The target will not be found if it is removed from the sequence. When does this occur?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If a pivot is to the left of and is greater than the target, then the target will be removed. The same occurs when the pivot is to the right of and is less than the target.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Since any element can be chosen as the pivot, for any target NOT to be removed, the condition described in the previous hint must never occur.
-</details>
diff --git a/problems/binary-string-with-substrings-representing-1-to-n/README.md b/problems/binary-string-with-substrings-representing-1-to-n/README.md
deleted file mode 100644
index 86dfded8d..000000000
--- a/problems/binary-string-with-substrings-representing-1-to-n/README.md
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-integer-divisible-by-k "Smallest Integer Divisible by K")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-to-base-2 "Convert to Base -2")
-
-## [1016. Binary String With Substrings Representing 1 To N (Medium)](https://leetcode.com/problems/binary-string-with-substrings-representing-1-to-n "子串能表示从 1 到 N 数字的二进制串")
-
-<p>Given a binary string <code>s</code> and a positive integer <code>n</code>, return <code>true</code><em> if the binary representation of all the integers in the range </em><code>[1, n]</code><em> are <strong>substrings</strong> of </em><code>s</code><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "0110", n = 3
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "0110", n = 4
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We only need to check substrings of length at most 20, because 10^6 has 20 bits.
-</details>
diff --git a/problems/binary-string-with-substrings-representing-1-to-n/binary_string_with_substrings_representing_1_to_n.go b/problems/binary-string-with-substrings-representing-1-to-n/binary_string_with_substrings_representing_1_to_n.go
deleted file mode 100644
index be4db217c..000000000
--- a/problems/binary-string-with-substrings-representing-1-to-n/binary_string_with_substrings_representing_1_to_n.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem1016
-
-import "strings"
-
-func queryString(S string, N int) bool {
-	end := N >> 1
-	for N >= end {
-		if !strings.Contains(S, binaryString(N)) {
-			return false
-		}
-		N--
-	}
-	return true
-}
-
-func binaryString(n int) string {
-	B := make([]byte, 0, 30)
-	for n > 0 {
-		B = append(B, byte(n&1)+'0')
-		n >>= 1
-	}
-	swap(B)
-	return string(B)
-}
-
-func swap(B []byte) {
-	i, j := 0, len(B)-1
-	for i < j {
-		B[i], B[j] = B[j], B[i]
-		i++
-		j--
-	}
-}
diff --git a/problems/binary-subarrays-with-sum/README.md b/problems/binary-subarrays-with-sum/README.md
deleted file mode 100644
index 775b0833f..000000000
--- a/problems/binary-subarrays-with-sum/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-email-addresses "Unique Email Addresses")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-falling-path-sum "Minimum Falling Path Sum")
-
-## [930. Binary Subarrays With Sum (Medium)](https://leetcode.com/problems/binary-subarrays-with-sum "和相同的二元子数组")
-
-<p>Given a binary array <code>nums</code> and an integer <code>goal</code>, return <em>the number of non-empty <strong>subarrays</strong> with a sum</em> <code>goal</code>.</p>
-
-<p>A <strong>subarray</strong> is a contiguous part of the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,0,1,0,1], goal = 2
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The 4 subarrays are bolded and underlined below:
-[<u><strong>1,0,1</strong></u>,0,1]
-[<u><strong>1,0,1,0</strong></u>,1]
-[1,<u><strong>0,1,0,1</strong></u>]
-[1,0,<u><strong>1,0,1</strong></u>]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,0,0,0], goal = 0
-<strong>Output:</strong> 15
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>nums[i]</code> is either <code>0</code> or <code>1</code>.</li>
-	<li><code>0 &lt;= goal &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
diff --git a/problems/binary-subarrays-with-sum/binary_subarrays_with_sum.go b/problems/binary-subarrays-with-sum/binary_subarrays_with_sum.go
deleted file mode 100644
index b3b8d7932..000000000
--- a/problems/binary-subarrays-with-sum/binary_subarrays_with_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem930
diff --git a/problems/binary-subarrays-with-sum/binary_subarrays_with_sum_test.go b/problems/binary-subarrays-with-sum/binary_subarrays_with_sum_test.go
deleted file mode 100644
index b3b8d7932..000000000
--- a/problems/binary-subarrays-with-sum/binary_subarrays_with_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem930
diff --git a/problems/binary-tree-cameras/README.md b/problems/binary-tree-cameras/README.md
deleted file mode 100644
index effd99d34..000000000
--- a/problems/binary-tree-cameras/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../numbers-with-same-consecutive-differences "Numbers With Same Consecutive Differences")
-　　　　　　　　　　　　　　　　
-[Next >](../pancake-sorting "Pancake Sorting")
-
-## [968. Binary Tree Cameras (Hard)](https://leetcode.com/problems/binary-tree-cameras "监控二叉树")
-
-<p>You are given the <code>root</code> of a binary tree. We install cameras on the tree nodes where each camera at a node can monitor its parent, itself, and its immediate children.</p>
-
-<p>Return <em>the minimum number of cameras needed to monitor all nodes of the tree</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/29/bst_cameras_01.png" style="width: 138px; height: 163px;" />
-<pre>
-<strong>Input:</strong> root = [0,0,null,0,0]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> One camera is enough to monitor all nodes if placed as shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/29/bst_cameras_02.png" style="width: 139px; height: 312px;" />
-<pre>
-<strong>Input:</strong> root = [0,0,null,0,null,0,null,null,0]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> At least two cameras are needed to monitor all nodes of the tree. The above image shows one of the valid configurations of camera placement.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 1000]</code>.</li>
-	<li><code>Node.val == 0</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Distribute Coins in Binary Tree](../distribute-coins-in-binary-tree) (Medium)
diff --git a/problems/binary-tree-cameras/binary_tree_cameras.go b/problems/binary-tree-cameras/binary_tree_cameras.go
deleted file mode 100644
index 3f5cdd844..000000000
--- a/problems/binary-tree-cameras/binary_tree_cameras.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem968
diff --git a/problems/binary-tree-coloring-game/README.md b/problems/binary-tree-coloring-game/README.md
deleted file mode 100644
index d1f3a7289..000000000
--- a/problems/binary-tree-coloring-game/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decrease-elements-to-make-array-zigzag "Decrease Elements To Make Array Zigzag")
-　　　　　　　　　　　　　　　　
-[Next >](../snapshot-array "Snapshot Array")
-
-## [1145. Binary Tree Coloring Game (Medium)](https://leetcode.com/problems/binary-tree-coloring-game "二叉树着色游戏")
-
-<p>Two players play a turn based game on a binary tree. We are given the <code>root</code> of this binary tree, and the number of nodes <code>n</code> in the tree. <code>n</code> is odd, and each node has a distinct value from <code>1</code> to <code>n</code>.</p>
-
-<p>Initially, the first player names a value <code>x</code> with <code>1 &lt;= x &lt;= n</code>, and the second player names a value <code>y</code> with <code>1 &lt;= y &lt;= n</code> and <code>y != x</code>. The first player colors the node with value <code>x</code> red, and the second player colors the node with value <code>y</code> blue.</p>
-
-<p>Then, the players take turns starting with the first player. In each turn, that player chooses a node of their color (red if player 1, blue if player 2) and colors an <strong>uncolored</strong> neighbor of the chosen node (either the left child, right child, or parent of the chosen node.)</p>
-
-<p>If (and only if) a player cannot choose such a node in this way, they must pass their turn. If both players pass their turn, the game ends, and the winner is the player that colored more nodes.</p>
-
-<p>You are the second player. If it is possible to choose such a <code>y</code> to ensure you win the game, return <code>true</code>. If it is not possible, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/08/01/1480-binary-tree-coloring-game.png" style="width: 500px; height: 310px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,6,7,8,9,10,11], n = 11, x = 3
-<strong>Output:</strong> true
-<strong>Explanation: </strong>The second player can choose the node with value 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,2,3], n = 3, x = 1
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is <code>n</code>.</li>
-	<li><code>1 &lt;= x &lt;= n &lt;= 100</code></li>
-	<li><code>n</code> is odd.</li>
-	<li>1 &lt;= Node.val &lt;= n</li>
-	<li>All the values of the tree are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The best move y must be immediately adjacent to x, since it locks out that subtree.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you count each of (up to) 3 different subtrees neighboring x?
-</details>
diff --git a/problems/binary-tree-inorder-traversal/README.md b/problems/binary-tree-inorder-traversal/README.md
deleted file mode 100644
index a64db82ed..000000000
--- a/problems/binary-tree-inorder-traversal/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../restore-ip-addresses "Restore IP Addresses")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-binary-search-trees-ii "Unique Binary Search Trees II")
-
-## [94. Binary Tree Inorder Traversal (Easy)](https://leetcode.com/problems/binary-tree-inorder-traversal "二叉树的中序遍历")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the inorder traversal of its nodes&#39; values</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/inorder_1.jpg" style="width: 202px; height: 324px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2,3]
-<strong>Output:</strong> [1,3,2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/inorder_5.jpg" style="width: 202px; height: 202px;" />
-<pre>
-<strong>Input:</strong> root = [1,2]
-<strong>Output:</strong> [2,1]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/inorder_4.jpg" style="width: 202px; height: 202px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2]
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 100]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Recursive solution is trivial, could you do it iteratively?
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Validate Binary Search Tree](../validate-binary-search-tree) (Medium)
-  1. [Binary Tree Preorder Traversal](../binary-tree-preorder-traversal) (Easy)
-  1. [Binary Tree Postorder Traversal](../binary-tree-postorder-traversal) (Easy)
-  1. [Binary Search Tree Iterator](../binary-search-tree-iterator) (Medium)
-  1. [Kth Smallest Element in a BST](../kth-smallest-element-in-a-bst) (Medium)
-  1. [Closest Binary Search Tree Value II](../closest-binary-search-tree-value-ii) (Hard)
-  1. [Inorder Successor in BST](../inorder-successor-in-bst) (Medium)
-  1. [Convert Binary Search Tree to Sorted Doubly Linked List](../convert-binary-search-tree-to-sorted-doubly-linked-list) (Medium)
-  1. [Minimum Distance Between BST Nodes](../minimum-distance-between-bst-nodes) (Easy)
diff --git a/problems/binary-tree-inorder-traversal/binary_tree_inorder_traversal.go b/problems/binary-tree-inorder-traversal/binary_tree_inorder_traversal.go
deleted file mode 100644
index e24e5d8e9..000000000
--- a/problems/binary-tree-inorder-traversal/binary_tree_inorder_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem94
diff --git a/problems/binary-tree-inorder-traversal/binary_tree_inorder_traversal_test.go b/problems/binary-tree-inorder-traversal/binary_tree_inorder_traversal_test.go
deleted file mode 100644
index e24e5d8e9..000000000
--- a/problems/binary-tree-inorder-traversal/binary_tree_inorder_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem94
diff --git a/problems/binary-tree-level-order-traversal-ii/README.md b/problems/binary-tree-level-order-traversal-ii/README.md
deleted file mode 100644
index 4cf8b3360..000000000
--- a/problems/binary-tree-level-order-traversal-ii/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-binary-tree-from-inorder-and-postorder-traversal "Construct Binary Tree from Inorder and Postorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-sorted-array-to-binary-search-tree "Convert Sorted Array to Binary Search Tree")
-
-## [107. Binary Tree Level Order Traversal II (Medium)](https://leetcode.com/problems/binary-tree-level-order-traversal-ii "二叉树的层序遍历 II")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the bottom-up level order traversal of its nodes&#39; values</em>. (i.e., from left to right, level by level from leaf to root).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/tree1.jpg" style="width: 277px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,null,null,15,7]
-<strong>Output:</strong> [[15,7],[9,20],[3]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [[1]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 2000]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Level Order Traversal](../binary-tree-level-order-traversal) (Medium)
-  1. [Average of Levels in Binary Tree](../average-of-levels-in-binary-tree) (Easy)
diff --git a/problems/binary-tree-level-order-traversal-ii/binary_tree_level_order_traversal_ii.go b/problems/binary-tree-level-order-traversal-ii/binary_tree_level_order_traversal_ii.go
deleted file mode 100644
index c24c80ae3..000000000
--- a/problems/binary-tree-level-order-traversal-ii/binary_tree_level_order_traversal_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem107
diff --git a/problems/binary-tree-level-order-traversal-ii/binary_tree_level_order_traversal_ii_test.go b/problems/binary-tree-level-order-traversal-ii/binary_tree_level_order_traversal_ii_test.go
deleted file mode 100644
index c24c80ae3..000000000
--- a/problems/binary-tree-level-order-traversal-ii/binary_tree_level_order_traversal_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem107
diff --git a/problems/binary-tree-level-order-traversal/README.md b/problems/binary-tree-level-order-traversal/README.md
deleted file mode 100644
index 60197a3e7..000000000
--- a/problems/binary-tree-level-order-traversal/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../symmetric-tree "Symmetric Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-zigzag-level-order-traversal "Binary Tree Zigzag Level Order Traversal")
-
-## [102. Binary Tree Level Order Traversal (Medium)](https://leetcode.com/problems/binary-tree-level-order-traversal "二叉树的层序遍历")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the level order traversal of its nodes&#39; values</em>. (i.e., from left to right, level by level).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/tree1.jpg" style="width: 277px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,null,null,15,7]
-<strong>Output:</strong> [[3],[9,20],[15,7]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [[1]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 2000]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Zigzag Level Order Traversal](../binary-tree-zigzag-level-order-traversal) (Medium)
-  1. [Binary Tree Level Order Traversal II](../binary-tree-level-order-traversal-ii) (Medium)
-  1. [Minimum Depth of Binary Tree](../minimum-depth-of-binary-tree) (Easy)
-  1. [Binary Tree Vertical Order Traversal](../binary-tree-vertical-order-traversal) (Medium)
-  1. [Average of Levels in Binary Tree](../average-of-levels-in-binary-tree) (Easy)
-  1. [N-ary Tree Level Order Traversal](../n-ary-tree-level-order-traversal) (Medium)
-  1. [Cousins in Binary Tree](../cousins-in-binary-tree) (Easy)
diff --git a/problems/binary-tree-level-order-traversal/binary_tree_level_order_traversal.go b/problems/binary-tree-level-order-traversal/binary_tree_level_order_traversal.go
deleted file mode 100644
index 2a1ce7079..000000000
--- a/problems/binary-tree-level-order-traversal/binary_tree_level_order_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem102
diff --git a/problems/binary-tree-level-order-traversal/binary_tree_level_order_traversal_test.go b/problems/binary-tree-level-order-traversal/binary_tree_level_order_traversal_test.go
deleted file mode 100644
index 2a1ce7079..000000000
--- a/problems/binary-tree-level-order-traversal/binary_tree_level_order_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem102
diff --git a/problems/binary-tree-longest-consecutive-sequence-ii/README.md b/problems/binary-tree-longest-consecutive-sequence-ii/README.md
deleted file mode 100644
index 04a3c7e03..000000000
--- a/problems/binary-tree-longest-consecutive-sequence-ii/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-array-with-equal-sum "Split Array with Equal Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../game-play-analysis-iv "Game Play Analysis IV")
-
-## [549. Binary Tree Longest Consecutive Sequence II (Medium)](https://leetcode.com/problems/binary-tree-longest-consecutive-sequence-ii "二叉树中最长的连续序列")
-
-<p>Given a binary tree, you need to find the length of Longest Consecutive Path in Binary Tree.</p>
-
-<p>Especially, this path can be either increasing or decreasing. For example, [1,2,3,4] and [4,3,2,1] are both considered valid, but the path [1,2,4,3] is not valid. On the other hand, the path can be in the child-Parent-child order, where not necessarily be parent-child order.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<b>Input:</b>
-        1
-       / \
-      2   3
-<b>Output:</b> 2
-<b>Explanation:</b> The longest consecutive path is [1, 2] or [2, 1].
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<b>Input:</b>
-        2
-       / \
-      1   3
-<b>Output:</b> 3
-<b>Explanation:</b> The longest consecutive path is [1, 2, 3] or [3, 2, 1].
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b> All the values of tree nodes are in the range of [-1e7, 1e7].</p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Longest Consecutive Sequence](../binary-tree-longest-consecutive-sequence) (Medium)
diff --git a/problems/binary-tree-longest-consecutive-sequence-ii/binary_tree_longest_consecutive_sequence_ii.go b/problems/binary-tree-longest-consecutive-sequence-ii/binary_tree_longest_consecutive_sequence_ii.go
deleted file mode 100644
index 6448485ca..000000000
--- a/problems/binary-tree-longest-consecutive-sequence-ii/binary_tree_longest_consecutive_sequence_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem549
diff --git a/problems/binary-tree-longest-consecutive-sequence-ii/binary_tree_longest_consecutive_sequence_ii_test.go b/problems/binary-tree-longest-consecutive-sequence-ii/binary_tree_longest_consecutive_sequence_ii_test.go
deleted file mode 100644
index 6448485ca..000000000
--- a/problems/binary-tree-longest-consecutive-sequence-ii/binary_tree_longest_consecutive_sequence_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem549
diff --git a/problems/binary-tree-longest-consecutive-sequence/README.md b/problems/binary-tree-longest-consecutive-sequence/README.md
deleted file mode 100644
index 555757df4..000000000
--- a/problems/binary-tree-longest-consecutive-sequence/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../serialize-and-deserialize-binary-tree "Serialize and Deserialize Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../bulls-and-cows "Bulls and Cows")
-
-## [298. Binary Tree Longest Consecutive Sequence (Medium)](https://leetcode.com/problems/binary-tree-longest-consecutive-sequence "二叉树最长连续序列")
-
-<p>Given a binary tree, find the length of the longest consecutive sequence path.</p>
-
-<p>The path refers to any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The longest consecutive path need to be from parent to child (cannot be the reverse).</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong>
-
-   1
-    \
-     3
-    / \
-   2   4
-        \
-         5
-
-<strong>Output:</strong> <code>3</code>
-
-<strong>Explanation: </strong>Longest consecutive sequence path is <code>3-4-5</code><span style="font-family: sans-serif, Arial, Verdana, &quot;Trebuchet MS&quot;;">, so return </span><code>3</code><span style="font-family: sans-serif, Arial, Verdana, &quot;Trebuchet MS&quot;;">.</span></pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:
-
-</strong>   2
-    \
-     3
-    / 
-   2    
-  / 
- 1
-
-<strong>Output: 2 
-
-Explanation: </strong>Longest consecutive sequence path is <code>2-3</code><span style="font-family: sans-serif, Arial, Verdana, &quot;Trebuchet MS&quot;;">, not </span><code>3-2-1</code><span style="font-family: sans-serif, Arial, Verdana, &quot;Trebuchet MS&quot;;">, so return </span><code>2</code><span style="font-family: sans-serif, Arial, Verdana, &quot;Trebuchet MS&quot;;">.</span></pre>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Longest Consecutive Sequence](../longest-consecutive-sequence) (Medium)
-  1. [Binary Tree Longest Consecutive Sequence II](../binary-tree-longest-consecutive-sequence-ii) (Medium)
diff --git a/problems/binary-tree-longest-consecutive-sequence/binary_tree_longest_consecutive_sequence.go b/problems/binary-tree-longest-consecutive-sequence/binary_tree_longest_consecutive_sequence.go
deleted file mode 100644
index ab404c8f3..000000000
--- a/problems/binary-tree-longest-consecutive-sequence/binary_tree_longest_consecutive_sequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem298
diff --git a/problems/binary-tree-longest-consecutive-sequence/binary_tree_longest_consecutive_sequence_test.go b/problems/binary-tree-longest-consecutive-sequence/binary_tree_longest_consecutive_sequence_test.go
deleted file mode 100644
index ab404c8f3..000000000
--- a/problems/binary-tree-longest-consecutive-sequence/binary_tree_longest_consecutive_sequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem298
diff --git a/problems/binary-tree-maximum-path-sum/README.md b/problems/binary-tree-maximum-path-sum/README.md
deleted file mode 100644
index 52c632575..000000000
--- a/problems/binary-tree-maximum-path-sum/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-time-to-buy-and-sell-stock-iii "Best Time to Buy and Sell Stock III")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-palindrome "Valid Palindrome")
-
-## [124. Binary Tree Maximum Path Sum (Hard)](https://leetcode.com/problems/binary-tree-maximum-path-sum "二叉树中的最大路径和")
-
-<p>A <strong>path</strong> in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequence <strong>at most once</strong>. Note that the path does not need to pass through the root.</p>
-
-<p>The <strong>path sum</strong> of a path is the sum of the node&#39;s values in the path.</p>
-
-<p>Given the <code>root</code> of a binary tree, return <em>the maximum <strong>path sum</strong> of any <strong>non-empty</strong> path</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/13/exx1.jpg" style="width: 322px; height: 182px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The optimal path is 2 -&gt; 1 -&gt; 3 with a path sum of 2 + 1 + 3 = 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/13/exx2.jpg" />
-<pre>
-<strong>Input:</strong> root = [-10,9,20,null,null,15,7]
-<strong>Output:</strong> 42
-<strong>Explanation:</strong> The optimal path is 15 -&gt; 20 -&gt; 7 with a path sum of 15 + 20 + 7 = 42.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 3 * 10<sup>4</sup>]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Path Sum](../path-sum) (Easy)
-  1. [Sum Root to Leaf Numbers](../sum-root-to-leaf-numbers) (Medium)
-  1. [Path Sum IV](../path-sum-iv) (Medium)
-  1. [Longest Univalue Path](../longest-univalue-path) (Medium)
-  1. [Time Needed to Inform All Employees](../time-needed-to-inform-all-employees) (Medium)
diff --git a/problems/binary-tree-maximum-path-sum/binary_tree_maximum_path_sum.go b/problems/binary-tree-maximum-path-sum/binary_tree_maximum_path_sum.go
deleted file mode 100644
index c1fc39b2a..000000000
--- a/problems/binary-tree-maximum-path-sum/binary_tree_maximum_path_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem124
diff --git a/problems/binary-tree-maximum-path-sum/binary_tree_maximum_path_sum_test.go b/problems/binary-tree-maximum-path-sum/binary_tree_maximum_path_sum_test.go
deleted file mode 100644
index c1fc39b2a..000000000
--- a/problems/binary-tree-maximum-path-sum/binary_tree_maximum_path_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem124
diff --git a/problems/binary-tree-paths/README.md b/problems/binary-tree-paths/README.md
deleted file mode 100644
index 7d34b50d0..000000000
--- a/problems/binary-tree-paths/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../paint-house "Paint House")
-　　　　　　　　　　　　　　　　
-[Next >](../add-digits "Add Digits")
-
-## [257. Binary Tree Paths (Easy)](https://leetcode.com/problems/binary-tree-paths "二叉树的所有路径")
-
-<p>Given the <code>root</code> of a binary tree, return <em>all root-to-leaf paths in <strong>any order</strong></em>.</p>
-
-<p>A <strong>leaf</strong> is a node with no children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/12/paths-tree.jpg" style="width: 207px; height: 293px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,null,5]
-<strong>Output:</strong> [&quot;1-&gt;2-&gt;5&quot;,&quot;1-&gt;3&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [&quot;1&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 100]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Path Sum II](../path-sum-ii) (Medium)
-  1. [Smallest String Starting From Leaf](../smallest-string-starting-from-leaf) (Medium)
diff --git a/problems/binary-tree-paths/binary_tree_paths.go b/problems/binary-tree-paths/binary_tree_paths.go
deleted file mode 100644
index 2879463d5..000000000
--- a/problems/binary-tree-paths/binary_tree_paths.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem257
diff --git a/problems/binary-tree-paths/binary_tree_paths_test.go b/problems/binary-tree-paths/binary_tree_paths_test.go
deleted file mode 100644
index 2879463d5..000000000
--- a/problems/binary-tree-paths/binary_tree_paths_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem257
diff --git a/problems/binary-tree-postorder-traversal/README.md b/problems/binary-tree-postorder-traversal/README.md
deleted file mode 100644
index 0828461f3..000000000
--- a/problems/binary-tree-postorder-traversal/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-preorder-traversal "Binary Tree Preorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../lru-cache "LRU Cache")
-
-## [145. Binary Tree Postorder Traversal (Easy)](https://leetcode.com/problems/binary-tree-postorder-traversal "二叉树的后序遍历")
-
-<p>Given the <code>root</code> of a&nbsp;binary tree, return <em>the postorder traversal of its nodes&#39; values</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/28/pre1.jpg" style="width: 202px; height: 317px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2,3]
-<strong>Output:</strong> [3,2,1]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/28/pre3.jpg" style="width: 202px; height: 197px;" />
-<pre>
-<strong>Input:</strong> root = [1,2]
-<strong>Output:</strong> [2,1]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/28/pre2.jpg" style="width: 202px; height: 197px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2]
-<strong>Output:</strong> [2,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of the nodes in the tree is in the range <code>[0, 100]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Recursive solution is trivial, could you do it iteratively?
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Inorder Traversal](../binary-tree-inorder-traversal) (Easy)
-  1. [N-ary Tree Postorder Traversal](../n-ary-tree-postorder-traversal) (Easy)
diff --git a/problems/binary-tree-postorder-traversal/binary_tree_postorder_traversal.go b/problems/binary-tree-postorder-traversal/binary_tree_postorder_traversal.go
deleted file mode 100644
index 7d85dff9a..000000000
--- a/problems/binary-tree-postorder-traversal/binary_tree_postorder_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem145
diff --git a/problems/binary-tree-postorder-traversal/binary_tree_postorder_traversal_test.go b/problems/binary-tree-postorder-traversal/binary_tree_postorder_traversal_test.go
deleted file mode 100644
index 7d85dff9a..000000000
--- a/problems/binary-tree-postorder-traversal/binary_tree_postorder_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem145
diff --git a/problems/binary-tree-preorder-traversal/README.md b/problems/binary-tree-preorder-traversal/README.md
deleted file mode 100644
index e0333b39e..000000000
--- a/problems/binary-tree-preorder-traversal/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reorder-list "Reorder List")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-postorder-traversal "Binary Tree Postorder Traversal")
-
-## [144. Binary Tree Preorder Traversal (Easy)](https://leetcode.com/problems/binary-tree-preorder-traversal "二叉树的前序遍历")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the preorder traversal of its nodes&#39; values</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/inorder_1.jpg" style="width: 202px; height: 324px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2,3]
-<strong>Output:</strong> [1,2,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/inorder_5.jpg" style="width: 202px; height: 202px;" />
-<pre>
-<strong>Input:</strong> root = [1,2]
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/inorder_4.jpg" style="width: 202px; height: 202px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2]
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 100]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Recursive solution is trivial, could you do it iteratively?</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Inorder Traversal](../binary-tree-inorder-traversal) (Easy)
-  1. [Verify Preorder Sequence in Binary Search Tree](../verify-preorder-sequence-in-binary-search-tree) (Medium)
-  1. [N-ary Tree Preorder Traversal](../n-ary-tree-preorder-traversal) (Easy)
diff --git a/problems/binary-tree-preorder-traversal/binary_tree_preorder_traversal.go b/problems/binary-tree-preorder-traversal/binary_tree_preorder_traversal.go
deleted file mode 100644
index 627bbf6e4..000000000
--- a/problems/binary-tree-preorder-traversal/binary_tree_preorder_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem144
diff --git a/problems/binary-tree-preorder-traversal/binary_tree_preorder_traversal_test.go b/problems/binary-tree-preorder-traversal/binary_tree_preorder_traversal_test.go
deleted file mode 100644
index 627bbf6e4..000000000
--- a/problems/binary-tree-preorder-traversal/binary_tree_preorder_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem144
diff --git a/problems/binary-tree-pruning/README.md b/problems/binary-tree-pruning/README.md
deleted file mode 100644
index 316f3dc32..000000000
--- a/problems/binary-tree-pruning/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-sum-of-averages "Largest Sum of Averages")
-　　　　　　　　　　　　　　　　
-[Next >](../bus-routes "Bus Routes")
-
-## [814. Binary Tree Pruning (Medium)](https://leetcode.com/problems/binary-tree-pruning "二叉树剪枝")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the same tree where every subtree (of the given tree) not containing a </em><code>1</code><em> has been removed</em>.</p>
-
-<p>A subtree of a node <code>node</code> is <code>node</code> plus every node that is a descendant of <code>node</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/04/06/1028_2.png" style="width: 500px; height: 140px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,0,0,1]
-<strong>Output:</strong> [1,null,0,null,1]
-<strong>Explanation:</strong> 
-Only the red nodes satisfy the property &quot;every subtree not containing a 1&quot;.
-The diagram on the right represents the answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/04/06/1028_1.png" style="width: 500px; height: 115px;" />
-<pre>
-<strong>Input:</strong> root = [1,0,1,0,0,0,1]
-<strong>Output:</strong> [1,null,1,null,1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/04/05/1028.png" style="width: 500px; height: 134px;" />
-<pre>
-<strong>Input:</strong> root = [1,1,0,1,1,0,1,0]
-<strong>Output:</strong> [1,1,0,1,1,null,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 200]</code>.</li>
-	<li><code>Node.val</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/binary-tree-pruning/binary_tree_pruning.go b/problems/binary-tree-pruning/binary_tree_pruning.go
deleted file mode 100644
index 3da5cce32..000000000
--- a/problems/binary-tree-pruning/binary_tree_pruning.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem814
diff --git a/problems/binary-tree-pruning/binary_tree_pruning_test.go b/problems/binary-tree-pruning/binary_tree_pruning_test.go
deleted file mode 100644
index 3da5cce32..000000000
--- a/problems/binary-tree-pruning/binary_tree_pruning_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem814
diff --git a/problems/binary-tree-right-side-view/README.md b/problems/binary-tree-right-side-view/README.md
deleted file mode 100644
index d005f8380..000000000
--- a/problems/binary-tree-right-side-view/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../house-robber "House Robber")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-islands "Number of Islands")
-
-## [199. Binary Tree Right Side View (Medium)](https://leetcode.com/problems/binary-tree-right-side-view "二叉树的右视图")
-
-<p>Given the <code>root</code> of a binary tree, imagine yourself standing on the <strong>right side</strong> of it, return <em>the values of the nodes you can see ordered from top to bottom</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/14/tree.jpg" style="width: 401px; height: 301px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,null,5,null,4]
-<strong>Output:</strong> [1,3,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,3]
-<strong>Output:</strong> [1,3]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 100]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Populating Next Right Pointers in Each Node](../populating-next-right-pointers-in-each-node) (Medium)
-  1. [Boundary of Binary Tree](../boundary-of-binary-tree) (Medium)
diff --git a/problems/binary-tree-right-side-view/binary_tree_right_side_view.go b/problems/binary-tree-right-side-view/binary_tree_right_side_view.go
deleted file mode 100644
index f29ea357a..000000000
--- a/problems/binary-tree-right-side-view/binary_tree_right_side_view.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem199
diff --git a/problems/binary-tree-right-side-view/binary_tree_right_side_view_test.go b/problems/binary-tree-right-side-view/binary_tree_right_side_view_test.go
deleted file mode 100644
index f29ea357a..000000000
--- a/problems/binary-tree-right-side-view/binary_tree_right_side_view_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem199
diff --git a/problems/binary-tree-tilt/README.md b/problems/binary-tree-tilt/README.md
deleted file mode 100644
index 39e9371ae..000000000
--- a/problems/binary-tree-tilt/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-line-of-consecutive-one-in-matrix "Longest Line of Consecutive One in Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-closest-palindrome "Find the Closest Palindrome")
-
-## [563. Binary Tree Tilt (Easy)](https://leetcode.com/problems/binary-tree-tilt "二叉树的坡度")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the sum of every tree node&#39;s <strong>tilt</strong>.</em></p>
-
-<p>The <strong>tilt</strong> of a tree node is the <b>absolute difference</b> between the sum of all left subtree node <strong>values</strong> and all right subtree node <strong>values</strong>. If a node does not have a left child, then the sum of the left subtree node <strong>values</strong> is treated as <code>0</code>. The rule is similar if there the node does not have a right child.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/20/tilt1.jpg" style="width: 712px; height: 182px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 
-Tilt of node 2 : |0-0| = 0 (no children)
-Tilt of node 3 : |0-0| = 0 (no children)
-Tilt of node 1 : |2-3| = 1 (left subtree is just left child, so sum is 2; right subtree is just right child, so sum is 3)
-Sum of every tilt : 0 + 0 + 1 = 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/20/tilt2.jpg" style="width: 800px; height: 203px;" />
-<pre>
-<strong>Input:</strong> root = [4,2,9,3,5,null,7]
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> 
-Tilt of node 3 : |0-0| = 0 (no children)
-Tilt of node 5 : |0-0| = 0 (no children)
-Tilt of node 7 : |0-0| = 0 (no children)
-Tilt of node 2 : |3-5| = 2 (left subtree is just left child, so sum is 3; right subtree is just right child, so sum is 5)
-Tilt of node 9 : |0-7| = 7 (no left child, so sum is 0; right subtree is just right child, so sum is 7)
-Tilt of node 4 : |(3+5+2)-(9+7)| = |10-16| = 6 (left subtree values are 3, 5, and 2, which sums to 10; right subtree values are 9 and 7, which sums to 16)
-Sum of every tilt : 0 + 0 + 0 + 2 + 7 + 6 = 15
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/20/tilt3.jpg" style="width: 800px; height: 293px;" />
-<pre>
-<strong>Input:</strong> root = [21,7,14,1,1,2,2,3,3]
-<strong>Output:</strong> 9
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Don't think too much, this is an easy problem. Take some small tree as an example.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can a parent node use the values of its child nodes? How will you implement it?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-May be recursion and tree traversal can help you in implementing.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-What about postorder traversal, using values of left and right childs?
-</details>
diff --git a/problems/binary-tree-tilt/binary_tree_tilt.go b/problems/binary-tree-tilt/binary_tree_tilt.go
deleted file mode 100644
index a5ae7cbfd..000000000
--- a/problems/binary-tree-tilt/binary_tree_tilt.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem563
diff --git a/problems/binary-tree-tilt/binary_tree_tilt_test.go b/problems/binary-tree-tilt/binary_tree_tilt_test.go
deleted file mode 100644
index a5ae7cbfd..000000000
--- a/problems/binary-tree-tilt/binary_tree_tilt_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem563
diff --git a/problems/binary-tree-upside-down/README.md b/problems/binary-tree-upside-down/README.md
deleted file mode 100644
index 9e4be9643..000000000
--- a/problems/binary-tree-upside-down/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../min-stack "Min Stack")
-　　　　　　　　　　　　　　　　
-[Next >](../read-n-characters-given-read4 "Read N Characters Given Read4")
-
-## [156. Binary Tree Upside Down (Medium)](https://leetcode.com/problems/binary-tree-upside-down "上下翻转二叉树")
-
-<p>Given a binary tree where all the right nodes are either leaf nodes with a sibling (a left node that shares the same parent node) or empty, flip it upside down and turn it into a tree where the original right nodes turned into left leaf nodes. Return the new root.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input: </strong>[1,2,3,4,5]
-
-    1
-   / \
-  2   3
- / \
-4   5
-
-<strong>Output:</strong> return the root of the binary tree [4,5,2,#,#,3,1]
-
-   4
-  / \
- 5   2
-    / \
-   3   1  
-</pre>
-
-<p><strong>Clarification:</strong></p>
-
-<p>Confused what <code>[4,5,2,#,#,3,1<font face="monospace">]</font></code>&nbsp;means? Read more below on how binary tree is serialized on OJ.</p>
-
-<p>The serialization of a binary tree follows a level order traversal, where &#39;#&#39; signifies a path terminator where no node exists below.</p>
-
-<p>Here&#39;s an example:</p>
-
-<pre>
-   1
-  / \
- 2   3
-    /
-   4
-    \
-     5
-</pre>
-
-<p>The above binary tree is serialized as <code>[1,2,3,#,#,4,#,#,5]</code>.</p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Reverse Linked List](../reverse-linked-list) (Easy)
diff --git a/problems/binary-tree-upside-down/binary_tree_upside_down.go b/problems/binary-tree-upside-down/binary_tree_upside_down.go
deleted file mode 100644
index 58eadce45..000000000
--- a/problems/binary-tree-upside-down/binary_tree_upside_down.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem156
diff --git a/problems/binary-tree-upside-down/binary_tree_upside_down_test.go b/problems/binary-tree-upside-down/binary_tree_upside_down_test.go
deleted file mode 100644
index 58eadce45..000000000
--- a/problems/binary-tree-upside-down/binary_tree_upside_down_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem156
diff --git a/problems/binary-tree-vertical-order-traversal/README.md b/problems/binary-tree-vertical-order-traversal/README.md
deleted file mode 100644
index a23002120..000000000
--- a/problems/binary-tree-vertical-order-traversal/README.md
+++ /dev/null
@@ -1,100 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../super-ugly-number "Super Ugly Number")
-　　　　　　　　　　　　　　　　
-[Next >](../count-of-smaller-numbers-after-self "Count of Smaller Numbers After Self")
-
-## [314. Binary Tree Vertical Order Traversal (Medium)](https://leetcode.com/problems/binary-tree-vertical-order-traversal "二叉树的垂直遍历")
-
-<p>Given a binary tree, return the <i>vertical order</i> traversal of its nodes&#39; values. (ie, from top to bottom, column by column).</p>
-
-<p>If two nodes are in the same row and column, the order should be from <b>left to right</b>.</p>
-
-<p><b>Examples 1:</b></p>
-
-<pre>
-<strong>Input:</strong> <code>[3,9,20,null,null,15,7]
-</code>
-   3
-  /\
- /  \
- 9  20
-    /\
-   /  \
-  15   7 
-
-<strong>Output:</strong>
-
-[
-  [9],
-  [3,15],
-  [20],
-  [7]
-]
-</pre>
-
-<p><b>Examples 2:</b></p>
-
-<pre>
-<strong>Input: </strong><code>[3,9,8,4,0,1,7]
-
-</code>     3
-    /\
-   /  \
-   9   8
-  /\  /\
- /  \/  \
- 4  01   7 
-
-<strong>Output:</strong>
-
-[
-  [4],
-  [9],
-  [3,0,1],
-  [8],
-  [7]
-]
-</pre>
-
-<p><b>Examples 3:</b></p>
-
-<pre>
-<strong>Input:</strong> <code>[3,9,8,4,0,1,7,null,null,null,2,5]</code> (0&#39;s right child is 2 and 1&#39;s left child is 5)
-
-     3
-    /\
-   /  \
-   9   8
-  /\  /\
- /  \/  \
- 4  01   7
-    /\
-   /  \
-   5   2
-
-<strong>Output:</strong>
-
-[
-  [4],
-  [9,5],
-  [3,0,1],
-  [8,2],
-  [7]
-]
-</pre>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Level Order Traversal](../binary-tree-level-order-traversal) (Medium)
diff --git a/problems/binary-tree-vertical-order-traversal/binary_tree_vertical_order_traversal.go b/problems/binary-tree-vertical-order-traversal/binary_tree_vertical_order_traversal.go
deleted file mode 100644
index 74f861737..000000000
--- a/problems/binary-tree-vertical-order-traversal/binary_tree_vertical_order_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem314
diff --git a/problems/binary-tree-vertical-order-traversal/binary_tree_vertical_order_traversal_test.go b/problems/binary-tree-vertical-order-traversal/binary_tree_vertical_order_traversal_test.go
deleted file mode 100644
index 74f861737..000000000
--- a/problems/binary-tree-vertical-order-traversal/binary_tree_vertical_order_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem314
diff --git a/problems/binary-tree-zigzag-level-order-traversal/README.md b/problems/binary-tree-zigzag-level-order-traversal/README.md
deleted file mode 100644
index b5819034d..000000000
--- a/problems/binary-tree-zigzag-level-order-traversal/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-level-order-traversal "Binary Tree Level Order Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-depth-of-binary-tree "Maximum Depth of Binary Tree")
-
-## [103. Binary Tree Zigzag Level Order Traversal (Medium)](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal "二叉树的锯齿形层序遍历")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the zigzag level order traversal of its nodes&#39; values</em>. (i.e., from left to right, then right to left for the next level and alternate between).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/tree1.jpg" style="width: 277px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,null,null,15,7]
-<strong>Output:</strong> [[3],[20,9],[15,7]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [[1]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 2000]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Level Order Traversal](../binary-tree-level-order-traversal) (Medium)
diff --git a/problems/binary-tree-zigzag-level-order-traversal/binary_tree_zigzag_level_order_traversal.go b/problems/binary-tree-zigzag-level-order-traversal/binary_tree_zigzag_level_order_traversal.go
deleted file mode 100644
index 110453694..000000000
--- a/problems/binary-tree-zigzag-level-order-traversal/binary_tree_zigzag_level_order_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem103
diff --git a/problems/binary-tree-zigzag-level-order-traversal/binary_tree_zigzag_level_order_traversal_test.go b/problems/binary-tree-zigzag-level-order-traversal/binary_tree_zigzag_level_order_traversal_test.go
deleted file mode 100644
index 110453694..000000000
--- a/problems/binary-tree-zigzag-level-order-traversal/binary_tree_zigzag_level_order_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem103
diff --git a/problems/binary-trees-with-factors/README.md b/problems/binary-trees-with-factors/README.md
deleted file mode 100644
index c944e4364..000000000
--- a/problems/binary-trees-with-factors/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../card-flipping-game "Card Flipping Game")
-　　　　　　　　　　　　　　　　
-[Next >](../goat-latin "Goat Latin")
-
-## [823. Binary Trees With Factors (Medium)](https://leetcode.com/problems/binary-trees-with-factors "带因子的二叉树")
-
-<p>Given an array of unique integers, <code>arr</code>, where each integer <code>arr[i]</code> is strictly greater than <code>1</code>.</p>
-
-<p>We make a binary tree using these integers, and each number may be used for any number of times. Each non-leaf node&#39;s value should be equal to the product of the values of its children.</p>
-
-<p>Return <em>the number of binary trees we can make</em>. The answer may be too large so return the answer <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,4]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We can make these trees: <code>[2], [4], [4, 2, 2]</code></pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,4,5,10]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> We can make these trees: <code>[2], [4], [5], [10], [4, 2, 2], [10, 2, 5], [10, 5, 2]</code>.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>2 &lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
-	<li>All the values of <code>arr</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/binary-trees-with-factors/binary_trees_with_factors.go b/problems/binary-trees-with-factors/binary_trees_with_factors.go
deleted file mode 100644
index a7e9873ed..000000000
--- a/problems/binary-trees-with-factors/binary_trees_with_factors.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem823
diff --git a/problems/binary-trees-with-factors/binary_trees_with_factors_test.go b/problems/binary-trees-with-factors/binary_trees_with_factors_test.go
deleted file mode 100644
index a7e9873ed..000000000
--- a/problems/binary-trees-with-factors/binary_trees_with_factors_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem823
diff --git a/problems/binary-watch/README.md b/problems/binary-watch/README.md
deleted file mode 100644
index 032afb9af..000000000
--- a/problems/binary-watch/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../nth-digit "Nth Digit")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-k-digits "Remove K Digits")
-
-## [401. Binary Watch (Easy)](https://leetcode.com/problems/binary-watch "二进制手表")
-
-<p>A binary watch has 4 LEDs on the top which represent the hours (0-11), and the 6 LEDs on the bottom represent the minutes (0-59). Each LED represents a zero or one, with the least significant bit on the right.</p>
-
-<ul>
-	<li>For example, the below binary watch reads <code>&quot;4:51&quot;</code>.</li>
-</ul>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/binarywatch.jpg" style="width: 500px; height: 500px;" /></p>
-
-<p>Given an integer <code>turnedOn</code> which represents the number of LEDs that are currently on, return <em>all possible times the watch could represent</em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>The hour must not contain a leading zero.</p>
-
-<ul>
-	<li>For example, <code>&quot;01:00&quot;</code> is not valid. It should be <code>&quot;1:00&quot;</code>.</li>
-</ul>
-
-<p>The minute must be consist of two digits and may contain a leading zero.</p>
-
-<ul>
-	<li>For example, <code>&quot;10:2&quot;</code> is not valid. It should be <code>&quot;10:02&quot;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> turnedOn = 1
-<strong>Output:</strong> ["0:01","0:02","0:04","0:08","0:16","0:32","1:00","2:00","4:00","8:00"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> turnedOn = 9
-<strong>Output:</strong> []
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= turnedOn &lt;= 10</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Letter Combinations of a Phone Number](../letter-combinations-of-a-phone-number) (Medium)
-  1. [Number of 1 Bits](../number-of-1-bits) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simplify by seeking for solutions that involve comparing bit counts.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Consider calculating all possible times for comparison purposes.
-</details>
diff --git a/problems/binary-watch/binary_watch.go b/problems/binary-watch/binary_watch.go
deleted file mode 100644
index 812950064..000000000
--- a/problems/binary-watch/binary_watch.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem401
diff --git a/problems/binary-watch/binary_watch_test.go b/problems/binary-watch/binary_watch_test.go
deleted file mode 100644
index 812950064..000000000
--- a/problems/binary-watch/binary_watch_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem401
diff --git a/problems/bitwise-and-of-numbers-range/README.md b/problems/bitwise-and-of-numbers-range/README.md
deleted file mode 100644
index fb838725c..000000000
--- a/problems/bitwise-and-of-numbers-range/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-islands "Number of Islands")
-　　　　　　　　　　　　　　　　
-[Next >](../happy-number "Happy Number")
-
-## [201. Bitwise AND of Numbers Range (Medium)](https://leetcode.com/problems/bitwise-and-of-numbers-range "数字范围按位与")
-
-<p>Given two integers <code>left</code> and <code>right</code> that represent the range <code>[left, right]</code>, return <em>the bitwise AND of all numbers in this range, inclusive</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = 5, right = 7
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = 0, right = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = 1, right = 2147483647
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= left &lt;= right &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
diff --git a/problems/bitwise-and-of-numbers-range/bitwise_and_of_numbers_range.go b/problems/bitwise-and-of-numbers-range/bitwise_and_of_numbers_range.go
deleted file mode 100644
index a54e63ea5..000000000
--- a/problems/bitwise-and-of-numbers-range/bitwise_and_of_numbers_range.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem201
diff --git a/problems/bitwise-and-of-numbers-range/bitwise_and_of_numbers_range_test.go b/problems/bitwise-and-of-numbers-range/bitwise_and_of_numbers_range_test.go
deleted file mode 100644
index a54e63ea5..000000000
--- a/problems/bitwise-and-of-numbers-range/bitwise_and_of_numbers_range_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem201
diff --git a/problems/bitwise-ors-of-subarrays/README.md b/problems/bitwise-ors-of-subarrays/README.md
deleted file mode 100644
index 1bc3dc5b0..000000000
--- a/problems/bitwise-ors-of-subarrays/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../increasing-order-search-tree "Increasing Order Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../orderly-queue "Orderly Queue")
-
-## [898. Bitwise ORs of Subarrays (Medium)](https://leetcode.com/problems/bitwise-ors-of-subarrays "子数组按位或操作")
-
-<p>We have an array <code>arr</code> of non-negative integers.</p>
-
-<p>For every (contiguous) subarray <code>sub = [arr[i], arr[i + 1], ..., arr[j]]</code> (with <code>i &lt;= j</code>), we take the bitwise OR of all the elements in <code>sub</code>, obtaining a result <code>arr[i] | arr[i + 1] | ... | arr[j]</code>.</p>
-
-<p>Return the number of possible results. Results that occur more than once are only counted once in the final answer</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [0]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There is only one possible result: 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,1,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The possible subarrays are [1], [1], [2], [1, 1], [1, 2], [1, 1, 2].
-These yield the results 1, 1, 2, 1, 3, 3.
-There are 3 unique values, so the answer is 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,4]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The possible results are 1, 2, 3, 4, 6, and 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i]&nbsp;&lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
diff --git a/problems/bitwise-ors-of-subarrays/bitwise_ors_of_subarrays.go b/problems/bitwise-ors-of-subarrays/bitwise_ors_of_subarrays.go
deleted file mode 100644
index 2d602dad9..000000000
--- a/problems/bitwise-ors-of-subarrays/bitwise_ors_of_subarrays.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem898
diff --git a/problems/bitwise-ors-of-subarrays/bitwise_ors_of_subarrays_test.go b/problems/bitwise-ors-of-subarrays/bitwise_ors_of_subarrays_test.go
deleted file mode 100644
index 2d602dad9..000000000
--- a/problems/bitwise-ors-of-subarrays/bitwise_ors_of_subarrays_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem898
diff --git a/problems/boats-to-save-people/README.md b/problems/boats-to-save-people/README.md
deleted file mode 100644
index e28fa8897..000000000
--- a/problems/boats-to-save-people/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decoded-string-at-index "Decoded String at Index")
-　　　　　　　　　　　　　　　　
-[Next >](../reachable-nodes-in-subdivided-graph "Reachable Nodes In Subdivided Graph")
-
-## [881. Boats to Save People (Medium)](https://leetcode.com/problems/boats-to-save-people "救生艇")
-
-<p>You are given an array <code>people</code> where <code>people[i]</code> is the weight of the <code>i<sup>th</sup></code> person, and an <strong>infinite number of boats</strong> where each boat can carry a maximum weight of <code>limit</code>. Each boat carries at most two people at the same time, provided the sum of the weight of those people is at most <code>limit</code>.</p>
-
-<p>Return <em>the minimum number of boats to carry every given person</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> people = [1,2], limit = 3
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 1 boat (1, 2)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> people = [3,2,2,1], limit = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 3 boats (1, 2), (2) and (3)
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> people = [3,5,3,4], limit = 5
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> 4 boats (3), (3), (4), (5)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= people.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= people[i] &lt;= limit &lt;= 3 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/boats-to-save-people/boats_to_save_people.go b/problems/boats-to-save-people/boats_to_save_people.go
deleted file mode 100644
index 0ddbd5738..000000000
--- a/problems/boats-to-save-people/boats_to_save_people.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem881
diff --git a/problems/boats-to-save-people/boats_to_save_people_test.go b/problems/boats-to-save-people/boats_to_save_people_test.go
deleted file mode 100644
index 0ddbd5738..000000000
--- a/problems/boats-to-save-people/boats_to_save_people_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem881
diff --git a/problems/bold-words-in-string/README.md b/problems/bold-words-in-string/README.md
deleted file mode 100644
index 30a868929..000000000
--- a/problems/bold-words-in-string/README.md
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../set-intersection-size-at-least-two "Set Intersection Size At Least Two")
-　　　　　　　　　　　　　　　　
-[Next >](../employee-free-time "Employee Free Time")
-
-## [758. Bold Words in String (Medium)](https://leetcode.com/problems/bold-words-in-string "字符串中的加粗单词")
-
-<p>
-Given a set of keywords <code>words</code> and a string <code>S</code>, make all appearances of all keywords in <code>S</code> bold.  Any letters between <code>&lt;b&gt;</code> and <code>&lt;/b&gt;</code> tags become bold.
-</p><p>
-The returned string should use the least number of tags possible, and of course the tags should form a valid combination.
-</p>
-<p>
-For example, given that <code>words = ["ab", "bc"]</code> and  <code>S = "aabcd"</code>, we should return <code>"a&lt;b&gt;abc&lt;/b&gt;d"</code>.  Note that returning <code>"a&lt;b&gt;a&lt;b&gt;b&lt;/b&gt;c&lt;/b&gt;d"</code> would use more tags, so it is incorrect.
-</p>
-
-<p><b>Note:</b><ol>
-<li><code>words</code> has length in range <code>[0, 50]</code>.</li>
-<li><code>words[i]</code> has length in range <code>[1, 10]</code>.</li>
-<li><code>S</code> has length in range <code>[0, 500]</code>.</li>
-<li>All characters in <code>words[i]</code> and <code>S</code> are lowercase letters.</li>
-</ol></p>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First, determine which letters are bold and store that information in mask[i] = if i-th character is bold.
-Then, insert the tags at the beginning and end of groups.  The start of a group is if and only if (mask[i] and (i == 0 or not mask[i-1])), and the end of a group is similar.
-</details>
diff --git a/problems/bold-words-in-string/bold_words_in_string.go b/problems/bold-words-in-string/bold_words_in_string.go
deleted file mode 100644
index 9e01008a2..000000000
--- a/problems/bold-words-in-string/bold_words_in_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem758
diff --git a/problems/bold-words-in-string/bold_words_in_string_test.go b/problems/bold-words-in-string/bold_words_in_string_test.go
deleted file mode 100644
index 9e01008a2..000000000
--- a/problems/bold-words-in-string/bold_words_in_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem758
diff --git a/problems/bomb-enemy/README.md b/problems/bomb-enemy/README.md
deleted file mode 100644
index d4e476cea..000000000
--- a/problems/bomb-enemy/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-transformed-array "Sort Transformed Array")
-　　　　　　　　　　　　　　　　
-[Next >](../design-hit-counter "Design Hit Counter")
-
-## [361. Bomb Enemy (Medium)](https://leetcode.com/problems/bomb-enemy "轰炸敌人")
-
-<p>Given a 2D grid, each cell is either a wall <code>&#39;W&#39;</code>, an enemy <code>&#39;E&#39;</code> or empty <code>&#39;0&#39;</code> (the number zero), return the maximum enemies you can kill using one bomb.<br />
-The bomb kills all the enemies in the same row and column from the planted point until it hits the wall since the wall is too strong to be destroyed.<br />
-<strong>Note: </strong>You can only put the bomb at an empty cell.</p>
-
-<p><strong>Example:</strong></p>
-
-<div>
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[[&quot;0&quot;,&quot;E&quot;,&quot;0&quot;,&quot;0&quot;],[&quot;E&quot;,&quot;0&quot;,&quot;W&quot;,&quot;E&quot;],[&quot;0&quot;,&quot;E&quot;,&quot;0&quot;,&quot;0&quot;]]</span>
-<strong>Output: </strong><span id="example-output-1">3 
-<strong>Explanation: </strong></span>For the given grid,
-
-0 E 0 0 
-E 0 W E 
-0 E 0 0
-
-Placing a bomb at (1,1) kills 3 enemies.
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/bomb-enemy/bomb_enemy.go b/problems/bomb-enemy/bomb_enemy.go
deleted file mode 100644
index 0cf0cb26d..000000000
--- a/problems/bomb-enemy/bomb_enemy.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem361
diff --git a/problems/bomb-enemy/bomb_enemy_test.go b/problems/bomb-enemy/bomb_enemy_test.go
deleted file mode 100644
index 0cf0cb26d..000000000
--- a/problems/bomb-enemy/bomb_enemy_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem361
diff --git a/problems/boundary-of-binary-tree/README.md b/problems/boundary-of-binary-tree/README.md
deleted file mode 100644
index 8b47a94b0..000000000
--- a/problems/boundary-of-binary-tree/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../output-contest-matches "Output Contest Matches")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-boxes "Remove Boxes")
-
-## [545. Boundary of Binary Tree (Medium)](https://leetcode.com/problems/boundary-of-binary-tree "二叉树的边界")
-
-<p>Given a binary tree, return the values of its boundary in <b>anti-clockwise</b> direction starting from root. Boundary includes left boundary, leaves, and right boundary in order without duplicate <strong>nodes</strong>.&nbsp; (The values of the nodes may still be duplicates.)</p>
-
-<p><b>Left boundary</b> is defined as the path from root to the <b>left-most</b> node. <b>Right boundary</b> is defined as the path from root to the <b>right-most</b> node. If the root doesn&#39;t have left subtree or right subtree, then the root itself is left boundary or right boundary. Note this definition only applies to the input binary tree, and not applies to any subtrees.</p>
-
-<p>The <b>left-most</b> node is defined as a <b>leaf</b> node you could reach when you always firstly travel to the left subtree if exists. If not, travel to the right subtree. Repeat until you reach a leaf node.</p>
-
-<p>The <b>right-most</b> node is also defined by the same way with left and right exchanged.</p>
-
-<p><b>Example 1</b></p>
-
-<pre>
-<b>Input:</b>
-  1
-   \
-    2
-   / \
-  3   4
-
-<b>Ouput:</b>
-[1, 3, 4, 2]
-
-<b>Explanation:</b>
-The root doesn&#39;t have left subtree, so the root itself is left boundary.
-The leaves are node 3 and 4.
-The right boundary are node 1,2,4. Note the anti-clockwise direction means you should output reversed right boundary.
-So order them in anti-clockwise without duplicates and we have [1,3,4,2].
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 2</b></p>
-
-<pre>
-<b>Input:</b>
-    ____1_____
-   /          \
-  2            3
- / \          / 
-4   5        6   
-   / \      / \
-  7   8    9  10  
-       
-<b>Ouput:</b>
-[1,2,4,7,8,9,10,6,3]
-
-<b>Explanation:</b>
-The left boundary are node 1,2,4. (4 is the left-most node according to definition)
-The leaves are node 4,7,8,9,10.
-The right boundary are node 1,3,6,10. (10 is the right-most node).
-So order them in anti-clockwise without duplicate nodes we have [1,2,4,7,8,9,10,6,3].
-</pre>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Right Side View](../binary-tree-right-side-view) (Medium)
diff --git a/problems/boundary-of-binary-tree/boundary_of_binary_tree.go b/problems/boundary-of-binary-tree/boundary_of_binary_tree.go
deleted file mode 100644
index 0032ca752..000000000
--- a/problems/boundary-of-binary-tree/boundary_of_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem545
diff --git a/problems/boundary-of-binary-tree/boundary_of_binary_tree_test.go b/problems/boundary-of-binary-tree/boundary_of_binary_tree_test.go
deleted file mode 100644
index 0032ca752..000000000
--- a/problems/boundary-of-binary-tree/boundary_of_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem545
diff --git a/problems/brace-expansion-ii/README.md b/problems/brace-expansion-ii/README.md
deleted file mode 100644
index b5dea6de0..000000000
--- a/problems/brace-expansion-ii/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-in-mountain-array "Find in Mountain Array")
-　　　　　　　　　　　　　　　　
-[Next >](../game-play-analysis-v "Game Play Analysis V")
-
-## [1096. Brace Expansion II (Hard)](https://leetcode.com/problems/brace-expansion-ii "花括号展开 II")
-
-<p>Under the grammar given below, strings can represent a set of lowercase words. Let&nbsp;<code>R(expr)</code>&nbsp;denote the set of words the expression represents.</p>
-
-<p>The grammar can best be understood through simple examples:</p>
-
-<ul>
-	<li>Single letters represent a singleton set containing that word.
-	<ul>
-		<li><code>R(&quot;a&quot;) = {&quot;a&quot;}</code></li>
-		<li><code>R(&quot;w&quot;) = {&quot;w&quot;}</code></li>
-	</ul>
-	</li>
-	<li>When we take a comma-delimited list of two or more expressions, we take the union of possibilities.
-	<ul>
-		<li><code>R(&quot;{a,b,c}&quot;) = {&quot;a&quot;,&quot;b&quot;,&quot;c&quot;}</code></li>
-		<li><code>R(&quot;{{a,b},{b,c}}&quot;) = {&quot;a&quot;,&quot;b&quot;,&quot;c&quot;}</code> (notice the final set only contains each word at most once)</li>
-	</ul>
-	</li>
-	<li>When we concatenate two expressions, we take the set of possible concatenations between two words where the first word comes from the first expression and the second word comes from the second expression.
-	<ul>
-		<li><code>R(&quot;{a,b}{c,d}&quot;) = {&quot;ac&quot;,&quot;ad&quot;,&quot;bc&quot;,&quot;bd&quot;}</code></li>
-		<li><code>R(&quot;a{b,c}{d,e}f{g,h}&quot;) = {&quot;abdfg&quot;, &quot;abdfh&quot;, &quot;abefg&quot;, &quot;abefh&quot;, &quot;acdfg&quot;, &quot;acdfh&quot;, &quot;acefg&quot;, &quot;acefh&quot;}</code></li>
-	</ul>
-	</li>
-</ul>
-
-<p>Formally, the three rules for our grammar:</p>
-
-<ul>
-	<li>For every lowercase letter <code>x</code>, we have <code>R(x) = {x}</code>.</li>
-	<li>For expressions <code>e<sub>1</sub>, e<sub>2</sub>, ... , e<sub>k</sub></code> with <code>k &gt;= 2</code>, we have <code>R({e<sub>1</sub>, e<sub>2</sub>, ...}) = R(e<sub>1</sub>) &cup; R(e<sub>2</sub>) &cup; ...</code></li>
-	<li>For expressions <code>e<sub>1</sub></code> and <code>e<sub>2</sub></code>, we have <code>R(e<sub>1</sub> + e<sub>2</sub>) = {a + b for (a, b) in R(e<sub>1</sub>) &times; R(e<sub>2</sub>)}</code>, where <code>+</code> denotes concatenation, and <code>&times;</code> denotes the cartesian product.</li>
-</ul>
-
-<p>Given an expression representing a set of words under the given grammar, return <em>the sorted list of words that the expression represents</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;{a,b}{c,{d,e}}&quot;
-<strong>Output:</strong> [&quot;ac&quot;,&quot;ad&quot;,&quot;ae&quot;,&quot;bc&quot;,&quot;bd&quot;,&quot;be&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;{{a,z},a{b,c},{ab,z}}&quot;
-<strong>Output:</strong> [&quot;a&quot;,&quot;ab&quot;,&quot;ac&quot;,&quot;z&quot;]
-<strong>Explanation:</strong> Each distinct word is written only once in the final answer.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= expression.length &lt;= 60</code></li>
-	<li><code>expression[i]</code> consists of <code>&#39;{&#39;</code>, <code>&#39;}&#39;</code>, <code>&#39;,&#39;</code>or lowercase English letters.</li>
-	<li>The given&nbsp;<code>expression</code>&nbsp;represents a set of words based on the grammar given in the description.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Brace Expansion](../brace-expansion) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can write helper methods to parse the next "chunk" of the expression.  If you see eg. "a", the answer is just the set {a}.  If you see "{", you parse until you complete the "}" (the number of { and } seen are equal) and that becomes a chunk that you find where the appropriate commas are, and parse each individual expression between the commas.
-</details>
diff --git a/problems/brace-expansion-ii/brace_expansion_ii.go b/problems/brace-expansion-ii/brace_expansion_ii.go
deleted file mode 100644
index bc0559311..000000000
--- a/problems/brace-expansion-ii/brace_expansion_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1096
diff --git a/problems/brace-expansion/README.md b/problems/brace-expansion/README.md
deleted file mode 100644
index 7aec2e852..000000000
--- a/problems/brace-expansion/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../high-five "High Five")
-　　　　　　　　　　　　　　　　
-[Next >](../confusing-number-ii "Confusing Number II")
-
-## [1087. Brace Expansion (Medium)](https://leetcode.com/problems/brace-expansion "花括号展开")
-
-<p>A string <code>S</code>&nbsp;represents a list of words.</p>
-
-<p>Each letter in the word has 1 or more options.&nbsp; If there is one option, the letter is represented as is.&nbsp; If there is more than one option, then curly braces delimit the options.&nbsp; For example, <code>&quot;{a,b,c}&quot;</code> represents options <code>[&quot;a&quot;, &quot;b&quot;, &quot;c&quot;]</code>.</p>
-
-<p>For example, <code>&quot;{a,b,c}d{e,f}&quot;</code> represents the list <code>[&quot;ade&quot;, &quot;adf&quot;, &quot;bde&quot;, &quot;bdf&quot;, &quot;cde&quot;, &quot;cdf&quot;]</code>.</p>
-
-<p>Return all words that can be formed in this manner, in lexicographical order.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">&quot;{a,b}c{d,e}f&quot;</span>
-<strong>Output: </strong><span id="example-output-1">[&quot;acdf&quot;,&quot;acef&quot;,&quot;bcdf&quot;,&quot;bcef&quot;]</span>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">&quot;abcd&quot;</span>
-<strong>Output: </strong><span id="example-output-2">[&quot;abcd&quot;]</span>
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= S.length &lt;= 50</code></li>
-	<li>There are no&nbsp;nested curly brackets.</li>
-	<li>All characters inside a pair of&nbsp;consecutive opening and ending curly brackets are different.</li>
-</ol>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Decode String](../decode-string) (Medium)
-  1. [Letter Case Permutation](../letter-case-permutation) (Medium)
-  1. [Brace Expansion II](../brace-expansion-ii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-All generated strings are of the same size. How can we generate all of these strings?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Do a backtracking on which each level of it has to choose one single (e.g. 'a') character or any character of the given parenthesized group (e.g. "{a,b,c}")
-</details>
diff --git a/problems/break-a-palindrome/README.md b/problems/break-a-palindrome/README.md
deleted file mode 100644
index aaaae4da1..000000000
--- a/problems/break-a-palindrome/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../list-the-products-ordered-in-a-period "List the Products Ordered in a Period")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-the-matrix-diagonally "Sort the Matrix Diagonally")
-
-## [1328. Break a Palindrome (Medium)](https://leetcode.com/problems/break-a-palindrome "破坏回文串")
-
-<p>Given a palindromic string of lowercase English letters <code>palindrome</code>, replace <strong>exactly one</strong> character with any lowercase English letter so that the resulting string is <strong>not</strong> a palindrome and that it is the <strong>lexicographically smallest</strong> one possible.</p>
-
-<p>Return <em>the resulting string. If there is no way to replace a character to make it not a palindrome, return an <strong>empty string</strong>.</em></p>
-
-<p>A string <code>a</code> is lexicographically smaller than a string <code>b</code> (of the same length) if in the first position where <code>a</code> and <code>b</code> differ, <code>a</code> has a character strictly smaller than the corresponding character in <code>b</code>. For example, <code>&quot;abcc&quot;</code> is lexicographically smaller than <code>&quot;abcd&quot;</code> because the first position they differ is at the fourth character, and <code>&#39;c&#39;</code> is smaller than <code>&#39;d&#39;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> palindrome = &quot;abccba&quot;
-<strong>Output:</strong> &quot;aaccba&quot;
-<strong>Explanation:</strong> There are many ways to make &quot;abccba&quot; not a palindrome, such as &quot;<u>z</u>bccba&quot;, &quot;a<u>a</u>ccba&quot;, and &quot;ab<u>a</u>cba&quot;.
-Of all the ways, &quot;aaccba&quot; is the lexicographically smallest.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> palindrome = &quot;a&quot;
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> There is no way to replace a single character to make &quot;a&quot; not a palindrome, so return an empty string.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= palindrome.length &lt;= 1000</code></li>
-	<li><code>palindrome</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to detect if there is impossible to perform the replacement? Only when the length = 1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Change the first non 'a' character to 'a'.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What if the string has only 'a'?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Change the last character to 'b'.
-</details>
diff --git a/problems/brick-wall/README.md b/problems/brick-wall/README.md
deleted file mode 100644
index 252c2432c..000000000
--- a/problems/brick-wall/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../optimal-division "Optimal Division")
-　　　　　　　　　　　　　　　　
-[Next >](../split-concatenated-strings "Split Concatenated Strings")
-
-## [554. Brick Wall (Medium)](https://leetcode.com/problems/brick-wall "砖墙")
-
-<p>There is a rectangular brick wall in front of you with <code>n</code> rows of bricks. The <code>i<sup>th</sup></code> row has some number of bricks each of the same height (i.e., one unit) but they can be of different widths. The total width of each row is the same.</p>
-
-<p>Draw a vertical line from the top to the bottom and cross the least bricks. If your line goes through the edge of a brick, then the brick is not considered as crossed. You cannot draw a line just along one of the two vertical edges of the wall, in which case the line will obviously cross no bricks.</p>
-
-<p>Given the 2D array <code>wall</code> that contains the information about the wall, return <em>the minimum number of crossed bricks after drawing such a vertical line</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/cutwall-grid.jpg" style="width: 493px; height: 577px;" />
-<pre>
-<strong>Input:</strong> wall = [[1,2,2,1],[3,1,2],[1,3,2],[2,4],[3,1,2],[1,3,1,1]]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> wall = [[1],[1],[1]]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == wall.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= wall[i].length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= sum(wall[i].length) &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>sum(wall[i])</code> is the same for each row <code>i</code>.</li>
-	<li><code>1 &lt;= wall[i][j] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
diff --git a/problems/brick-wall/brick_wall.go b/problems/brick-wall/brick_wall.go
deleted file mode 100644
index 9da17e427..000000000
--- a/problems/brick-wall/brick_wall.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem554
diff --git a/problems/brick-wall/brick_wall_test.go b/problems/brick-wall/brick_wall_test.go
deleted file mode 100644
index 9da17e427..000000000
--- a/problems/brick-wall/brick_wall_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem554
diff --git a/problems/bricks-falling-when-hit/README.md b/problems/bricks-falling-when-hit/README.md
deleted file mode 100644
index 9720c2f60..000000000
--- a/problems/bricks-falling-when-hit/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-eventual-safe-states "Find Eventual Safe States")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-morse-code-words "Unique Morse Code Words")
-
-## [803. Bricks Falling When Hit (Hard)](https://leetcode.com/problems/bricks-falling-when-hit "打砖块")
-
-<p>You are given an <code>m x n</code> binary <code>grid</code>, where each <code>1</code> represents a brick and <code>0</code> represents an empty space. A brick is <strong>stable</strong> if:</p>
-
-<ul>
-	<li>It is directly connected to the top of the grid, or</li>
-	<li>At least one other brick in its four adjacent cells is <strong>stable</strong>.</li>
-</ul>
-
-<p>You are also given an array <code>hits</code>, which is a sequence of erasures we want to apply. Each time we want to erase the brick at the location <code>hits[i] = (row<sub>i</sub>, col<sub>i</sub>)</code>. The brick on that location&nbsp;(if it exists) will disappear. Some other bricks may no longer be stable because of that erasure and will <strong>fall</strong>. Once a brick falls, it is <strong>immediately</strong> erased from the <code>grid</code> (i.e., it does not land on other stable bricks).</p>
-
-<p>Return <em>an array </em><code>result</code><em>, where each </em><code>result[i]</code><em> is the number of bricks that will <strong>fall</strong> after the </em><code>i<sup>th</sup></code><em> erasure is applied.</em></p>
-
-<p><strong>Note</strong> that an erasure may refer to a location with no brick, and if it does, no bricks drop.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,0,0,0],[1,1,1,0]], hits = [[1,0]]
-<strong>Output:</strong> [2]
-<strong>Explanation: </strong>Starting with the grid:
-[[1,0,0,0],
- [<u>1</u>,1,1,0]]
-We erase the underlined brick at (1,0), resulting in the grid:
-[[1,0,0,0],
- [0,<u>1</u>,<u>1</u>,0]]
-The two underlined bricks are no longer stable as they are no longer connected to the top nor adjacent to another stable brick, so they will fall. The resulting grid is:
-[[1,0,0,0],
- [0,0,0,0]]
-Hence the result is [2].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,0,0,0],[1,1,0,0]], hits = [[1,1],[1,0]]
-<strong>Output:</strong> [0,0]
-<strong>Explanation: </strong>Starting with the grid:
-[[1,0,0,0],
- [1,<u>1</u>,0,0]]
-We erase the underlined brick at (1,1), resulting in the grid:
-[[1,0,0,0],
- [1,0,0,0]]
-All remaining bricks are still stable, so no bricks fall. The grid remains the same:
-[[1,0,0,0],
- [<u>1</u>,0,0,0]]
-Next, we erase the underlined brick at (1,0), resulting in the grid:
-[[1,0,0,0],
- [0,0,0,0]]
-Once again, all remaining bricks are still stable, so no bricks fall.
-Hence the result is [0,0].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>grid[i][j]</code> is <code>0</code> or <code>1</code>.</li>
-	<li><code>1 &lt;= hits.length &lt;= 4 * 10<sup>4</sup></code></li>
-	<li><code>hits[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>i&nbsp;</sub>&lt;= m - 1</code></li>
-	<li><code>0 &lt;=&nbsp;y<sub>i</sub> &lt;= n - 1</code></li>
-	<li>All <code>(x<sub>i</sub>, y<sub>i</sub>)</code> are unique.</li>
-</ul>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/bricks-falling-when-hit/bricks_falling_when_hit.go b/problems/bricks-falling-when-hit/bricks_falling_when_hit.go
deleted file mode 100644
index ba1c94887..000000000
--- a/problems/bricks-falling-when-hit/bricks_falling_when_hit.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem803
diff --git a/problems/bricks-falling-when-hit/bricks_falling_when_hit_test.go b/problems/bricks-falling-when-hit/bricks_falling_when_hit_test.go
deleted file mode 100644
index ba1c94887..000000000
--- a/problems/bricks-falling-when-hit/bricks_falling_when_hit_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem803
diff --git a/problems/brightest-position-on-street/README.md b/problems/brightest-position-on-street/README.md
deleted file mode 100644
index 0aaf7cc50..000000000
--- a/problems/brightest-position-on-street/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-accounts-that-did-not-stream "Number of Accounts That Did Not Stream")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-1d-array-into-2d-array "Convert 1D Array Into 2D Array")
-
-## [2021. Brightest Position on Street (Medium)](https://leetcode.com/problems/brightest-position-on-street "街上最亮的位置")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert lights into an array of ranges representing the range where each street light can light up and sort the start and end points of the ranges.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Do we need to traverse all possible positions on the street?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-No, we don't, we only need to go to the start and end points of the ranges for each streetlight.
-</details>
diff --git a/problems/broken-calculator/README.md b/problems/broken-calculator/README.md
deleted file mode 100644
index cd680fffa..000000000
--- a/problems/broken-calculator/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../satisfiability-of-equality-equations "Satisfiability of Equality Equations")
-　　　　　　　　　　　　　　　　
-[Next >](../subarrays-with-k-different-integers "Subarrays with K Different Integers")
-
-## [991. Broken Calculator (Medium)](https://leetcode.com/problems/broken-calculator "坏了的计算器")
-
-<p>There is a broken calculator that has the integer <code>startValue</code> on its display initially. In on operation you can:</p>
-
-<ul>
-	<li>multiply the number on the display by <code>2</code>, or</li>
-	<li>subtract <code>1</code> from the number on the display.</li>
-</ul>
-
-<p>Given two integers <code>startValue</code> and <code>target</code>, return <em>the minimum number of operations needed to display </em><code>target</code><em> on the calculator</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> startValue = 2, target = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Use double operation and then decrement operation {2 -&gt; 4 -&gt; 3}.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> startValue = 5, target = 8
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Use decrement and then double {5 -&gt; 4 -&gt; 8}.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> startValue = 3, target = 10
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Use double, decrement and double {3 -&gt; 6 -&gt; 5 -&gt; 10}.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> startValue = 1024, target = 1
-<strong>Output:</strong> 1023
-<strong>Explanation:</strong> Use decrement operations 1023 times.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= x, y &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [2 Keys Keyboard](../2-keys-keyboard) (Medium)
diff --git a/problems/broken-calculator/broken_calculator.go b/problems/broken-calculator/broken_calculator.go
deleted file mode 100644
index 27bb583d4..000000000
--- a/problems/broken-calculator/broken_calculator.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem991
diff --git a/problems/buddy-strings/README.md b/problems/buddy-strings/README.md
deleted file mode 100644
index ebe14bc06..000000000
--- a/problems/buddy-strings/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../mirror-reflection "Mirror Reflection")
-　　　　　　　　　　　　　　　　
-[Next >](../lemonade-change "Lemonade Change")
-
-## [859. Buddy Strings (Easy)](https://leetcode.com/problems/buddy-strings "亲密字符串")
-
-<p>Given two strings <code>s</code> and <code>goal</code>, return <code>true</code><em> if you can swap two letters in </em><code>s</code><em> so the result is equal to </em><code>goal</code><em>, otherwise, return </em><code>false</code><em>.</em></p>
-
-<p>Swapping letters is defined as taking two indices <code>i</code> and <code>j</code> (0-indexed) such that <code>i != j</code> and swapping the characters at <code>s[i]</code> and <code>s[j]</code>.</p>
-
-<ul>
-	<li>For example, swapping at indices <code>0</code> and <code>2</code> in <code>&quot;abcd&quot;</code> results in <code>&quot;cbad&quot;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ab&quot;, goal = &quot;ba&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can swap s[0] = &#39;a&#39; and s[1] = &#39;b&#39; to get &quot;ba&quot;, which is equal to goal.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ab&quot;, goal = &quot;ab&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The only letters you can swap are s[0] = &#39;a&#39; and s[1] = &#39;b&#39;, which results in &quot;ba&quot; != goal.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aa&quot;, goal = &quot;aa&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can swap s[0] = &#39;a&#39; and s[1] = &#39;a&#39; to get &quot;aa&quot;, which is equal to goal.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaaaaaabc&quot;, goal = &quot;aaaaaaacb&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, goal.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>s</code> and <code>goal</code> consist of lowercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/buddy-strings/buddy_strings.go b/problems/buddy-strings/buddy_strings.go
deleted file mode 100644
index d21408dff..000000000
--- a/problems/buddy-strings/buddy_strings.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem859
-
-func buddyStrings(A string, B string) bool {
-	if len(A) != len(B) {
-		return false
-	}
-	if A == B {
-		exist := [26]bool{}
-		for _, c := range A {
-			k := c - 'a'
-			if exist[k] {
-				return true
-			}
-			exist[k] = true
-		}
-		return false
-	}
-	m, n := -1, -1
-	for i, c := range A {
-		if B[i] != byte(c) {
-			if m == -1 {
-				m = i
-			} else if n == -1 {
-				n = i
-			} else {
-				return false
-			}
-		}
-	}
-	return n != -1 && A[m] == B[n] && A[n] == B[m]
-}
diff --git a/problems/buddy-strings/buddy_strings_test.go b/problems/buddy-strings/buddy_strings_test.go
deleted file mode 100644
index 28ab9045e..000000000
--- a/problems/buddy-strings/buddy_strings_test.go
+++ /dev/null
@@ -1,55 +0,0 @@
-package problem859
-
-import "testing"
-
-type testType struct {
-	a    string
-	b    string
-	want bool
-}
-
-func TestBuddyStrings(t *testing.T) {
-	tests := [...]testType{
-		{
-			a:    "ab",
-			b:    "ba",
-			want: true,
-		},
-		{
-			a:    "aa",
-			b:    "aa",
-			want: true,
-		},
-		{
-			a:    "ab",
-			b:    "ab",
-			want: false,
-		},
-		{
-			a:    "aaaaaaabc",
-			b:    "aaaaaaacb",
-			want: true,
-		},
-		{
-			a:    "",
-			b:    "aa",
-			want: false,
-		},
-		{
-			a:    "hello",
-			b:    "h0lle",
-			want: false,
-		},
-		{
-			a:    "hello",
-			b:    "hanna",
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := buddyStrings(tt.a, tt.b)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.a, tt.b, got, tt.want)
-		}
-	}
-}
diff --git a/problems/build-an-array-with-stack-operations/README.md b/problems/build-an-array-with-stack-operations/README.md
deleted file mode 100644
index 15700b124..000000000
--- a/problems/build-an-array-with-stack-operations/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../evaluate-boolean-expression "Evaluate Boolean Expression")
-　　　　　　　　　　　　　　　　
-[Next >](../count-triplets-that-can-form-two-arrays-of-equal-xor "Count Triplets That Can Form Two Arrays of Equal XOR")
-
-## [1441. Build an Array With Stack Operations (Easy)](https://leetcode.com/problems/build-an-array-with-stack-operations "用栈操作构建数组")
-
-<p>You are given an array <code>target</code> and an integer <code>n</code>.</p>
-
-<p>In each iteration, you will read a number from <code>list = [1, 2, 3, ..., n]</code>.</p>
-
-<p>Build the <code>target</code> array using the following operations:</p>
-
-<ul>
-	<li><code>&quot;Push&quot;</code>: Reads a new element from the beginning list, and pushes it in the array.</li>
-	<li><code>&quot;Pop&quot;</code>: Deletes the last element of the array.</li>
-	<li>If the target array is already built, stop reading more elements.</li>
-</ul>
-
-<p>Return <em>a list of the operations needed to build </em><code>target</code>. The test cases are generated so that the answer is <strong>unique</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [1,3], n = 3
-<strong>Output:</strong> [&quot;Push&quot;,&quot;Push&quot;,&quot;Pop&quot;,&quot;Push&quot;]
-<strong>Explanation:</strong> 
-Read number 1 and automatically push in the array -&gt; [1]
-Read number 2 and automatically push in the array then Pop it -&gt; [1]
-Read number 3 and automatically push in the array -&gt; [1,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [1,2,3], n = 3
-<strong>Output:</strong> [&quot;Push&quot;,&quot;Push&quot;,&quot;Push&quot;]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [1,2], n = 4
-<strong>Output:</strong> [&quot;Push&quot;,&quot;Push&quot;]
-<strong>Explanation:</strong> You only need to read the first 2 numbers and stop.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= target.length &lt;= 100</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= target[i] &lt;= n</code></li>
-	<li><code>target</code> is strictly increasing.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use “Push” for numbers to be kept in target array and [“Push”, “Pop”] for numbers to be discarded.
-</details>
diff --git a/problems/build-array-from-permutation/README.md b/problems/build-array-from-permutation/README.md
deleted file mode 100644
index e72aa6eb5..000000000
--- a/problems/build-array-from-permutation/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../leetcodify-similar-friends "Leetcodify Similar Friends")
-　　　　　　　　　　　　　　　　
-[Next >](../eliminate-maximum-number-of-monsters "Eliminate Maximum Number of Monsters")
-
-## [1920. Build Array from Permutation (Easy)](https://leetcode.com/problems/build-array-from-permutation "基于排列构建数组")
-
-<p>Given a <strong>zero-based permutation</strong> <code>nums</code> (<strong>0-indexed</strong>), build an array <code>ans</code> of the <strong>same length</strong> where <code>ans[i] = nums[nums[i]]</code> for each <code>0 &lt;= i &lt; nums.length</code> and return it.</p>
-
-<p>A <strong>zero-based permutation</strong> <code>nums</code> is an array of <strong>distinct</strong> integers from <code>0</code> to <code>nums.length - 1</code> (<strong>inclusive</strong>).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,2,1,5,3,4]
-<strong>Output:</strong> [0,1,2,4,5,3]<strong>
-Explanation:</strong> The array ans is built as follows: 
-ans = [nums[nums[0]], nums[nums[1]], nums[nums[2]], nums[nums[3]], nums[nums[4]], nums[nums[5]]]
-    = [nums[0], nums[2], nums[1], nums[5], nums[3], nums[4]]
-    = [0,1,2,4,5,3]</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,0,1,2,3,4]
-<strong>Output:</strong> [4,5,0,1,2,3]
-<strong>Explanation:</strong> The array ans is built as follows:
-ans = [nums[nums[0]], nums[nums[1]], nums[nums[2]], nums[nums[3]], nums[nums[4]], nums[nums[5]]]
-    = [nums[5], nums[0], nums[1], nums[2], nums[3], nums[4]]
-    = [4,5,0,1,2,3]</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt; nums.length</code></li>
-	<li>The elements in <code>nums</code> are <strong>distinct</strong>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow-up:</strong> Can you solve it without using an extra space (i.e., <code>O(1)</code> memory)?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Just apply what's said in the statement.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Notice that you can't apply it on the same array directly since some elements will change after application
-</details>
diff --git a/problems/build-array-where-you-can-find-the-maximum-exactly-k-comparisons/README.md b/problems/build-array-where-you-can-find-the-maximum-exactly-k-comparisons/README.md
deleted file mode 100644
index a375d8613..000000000
--- a/problems/build-array-where-you-can-find-the-maximum-exactly-k-comparisons/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-frogs-croaking "Minimum Number of Frogs Croaking")
-　　　　　　　　　　　　　　　　
-[Next >](../npv-queries "NPV Queries")
-
-## [1420. Build Array Where You Can Find The Maximum Exactly K Comparisons (Hard)](https://leetcode.com/problems/build-array-where-you-can-find-the-maximum-exactly-k-comparisons "生成数组")
-
-<p>Given three integers <code>n</code>, <code>m</code> and <code>k</code>. Consider the following algorithm to find the maximum element of an array of positive integers:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/04/02/e.png" style="width: 424px; height: 372px;" />
-<p>You should build the array arr which has the following properties:</p>
-
-<ul>
-	<li><code>arr</code> has exactly <code>n</code> integers.</li>
-	<li><code>1 &lt;= arr[i] &lt;= m</code> where <code>(0 &lt;= i &lt; n)</code>.</li>
-	<li>After applying the mentioned algorithm to <code>arr</code>, the value <code>search_cost</code> is equal to <code>k</code>.</li>
-</ul>
-
-<p>Return <em>the number of ways</em> to build the array <code>arr</code> under the mentioned conditions.&nbsp;As the answer may grow large, the answer&nbsp;<strong>must be</strong>&nbsp;computed modulo&nbsp;<code>10^9 + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, m = 3, k = 1
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The possible arrays are [1, 1], [2, 1], [2, 2], [3, 1], [3, 2] [3, 3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, m = 2, k = 3
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no possible arrays that satisify the mentioned conditions.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 9, m = 1, k = 1
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only possible array is [1, 1, 1, 1, 1, 1, 1, 1, 1]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 50, m = 100, k = 25
-<strong>Output:</strong> 34549172
-<strong>Explanation:</strong> Don&#39;t forget to compute the answer modulo 1000000007
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 37, m = 17, k = 7
-<strong>Output:</strong> 418930126
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 50</code></li>
-	<li><code>1 &lt;= m &lt;= 100</code></li>
-	<li><code>0 &lt;= k &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming approach. Build dp table where dp[a][b][c] is the number of ways you can start building the array starting from index a where the search_cost = c and the maximum used integer was b.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Recursively, solve the small sub-problems first. Optimize your answer by stopping the search if you exceeded k changes.
-</details>
diff --git a/problems/build-binary-expression-tree-from-infix-expression/README.md b/problems/build-binary-expression-tree-from-infix-expression/README.md
deleted file mode 100644
index ccb059a16..000000000
--- a/problems/build-binary-expression-tree-from-infix-expression/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-most-frequently-ordered-products-for-each-customer "The Most Frequently Ordered Products for Each Customer")
-　　　　　　　　　　　　　　　　
-[Next >](../crawler-log-folder "Crawler Log Folder")
-
-## [1597. Build Binary Expression Tree From Infix Expression (Hard)](https://leetcode.com/problems/build-binary-expression-tree-from-infix-expression "根据中缀表达式构造二叉表达式树")
-
-
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Basic Calculator III](../basic-calculator-iii) (Hard)
-  1. [Check If Two Expression Trees are Equivalent](../check-if-two-expression-trees-are-equivalent) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert infix expression to postfix expression.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Build an expression tree from the postfix expression.
-</details>
diff --git a/problems/build-the-equation/README.md b/problems/build-the-equation/README.md
deleted file mode 100644
index 1a035a2c2..000000000
--- a/problems/build-the-equation/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../abbreviating-the-product-of-a-range "Abbreviating the Product of a Range")
-　　　　　　　　　　　　　　　　
-[Next >](../a-number-after-a-double-reversal "A Number After a Double Reversal")
-
-## [2118. Build the Equation (Hard)](https://leetcode.com/problems/build-the-equation "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/build-the-equation/mysql_schemas.sql b/problems/build-the-equation/mysql_schemas.sql
deleted file mode 100644
index 9cb986611..000000000
--- a/problems/build-the-equation/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create table If Not Exists Terms (power int, factor int);
-Truncate table Terms;
-insert into Terms (power, factor) values ('2', '1');
-insert into Terms (power, factor) values ('1', '-4');
-insert into Terms (power, factor) values ('0', '2');
diff --git a/problems/building-boxes/README.md b/problems/building-boxes/README.md
deleted file mode 100644
index 55d42ffd8..000000000
--- a/problems/building-boxes/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-kth-largest-xor-coordinate-value "Find Kth Largest XOR Coordinate Value")
-　　　　　　　　　　　　　　　　
-[Next >](../find-distance-in-a-binary-tree "Find Distance in a Binary Tree")
-
-## [1739. Building Boxes (Hard)](https://leetcode.com/problems/building-boxes "放置盒子")
-
-<p>You have a cubic storeroom where the width, length, and height of the room are all equal to <code>n</code> units. You are asked to place <code>n</code> boxes in this room where each box is a cube of unit side length. There are however some rules to placing the boxes:</p>
-
-<ul>
-	<li>You can place the boxes anywhere on the floor.</li>
-	<li>If box <code>x</code> is placed on top of the box <code>y</code>, then each side of the four vertical sides of the box <code>y</code> <strong>must</strong> either be adjacent to another box or to a wall.</li>
-</ul>
-
-<p>Given an integer <code>n</code>, return<em> the <strong>minimum</strong> possible number of boxes touching the floor.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/3-boxes.png" style="width: 135px; height: 143px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The figure above is for the placement of the three boxes.
-These boxes are placed in the corner of the room, where the corner is on the left side.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/4-boxes.png" style="width: 135px; height: 179px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The figure above is for the placement of the four boxes.
-These boxes are placed in the corner of the room, where the corner is on the left side.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/10-boxes.png" style="width: 271px; height: 257px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The figure above is for the placement of the ten boxes.
-These boxes are placed in the corner of the room, where the corner is on the back side.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Suppose We can put m boxes on the floor, within all the ways to put the boxes, what’s the maximum number of boxes we can put in?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The first box should always start in the corner
-</details>
diff --git a/problems/building-h2o/README.md b/problems/building-h2o/README.md
deleted file mode 100644
index a449643cb..000000000
--- a/problems/building-h2o/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../print-zero-even-odd "Print Zero Even Odd")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-days-in-a-month "Number of Days in a Month")
-
-## [1117. Building H2O (Medium)](https://leetcode.com/problems/building-h2o "H2O 生成")
-
-<p>There are two kinds of threads: <code>oxygen</code> and <code>hydrogen</code>. Your goal is to group these threads to form water molecules.</p>
-
-<p>There is a barrier where each thread has to wait until a complete molecule can be formed. Hydrogen and oxygen threads will be given <code>releaseHydrogen</code> and <code>releaseOxygen</code> methods respectively, which will allow them to pass the barrier. These threads should pass the barrier in groups of three, and they must immediately bond with each other to form a water molecule. You must guarantee that all the threads from one molecule bond before any other threads from the next molecule do.</p>
-
-<p>In other words:</p>
-
-<ul>
-	<li>If an oxygen thread arrives at the barrier when no hydrogen threads are present, it must wait for two hydrogen threads.</li>
-	<li>If a hydrogen thread arrives at the barrier when no other threads are present, it must wait for an oxygen thread and another hydrogen thread.</li>
-</ul>
-
-<p>We do not have to worry about matching the threads up explicitly; the threads do not necessarily know which other threads they are paired up with. The key is that threads pass the barriers in complete sets; thus, if we examine the sequence of threads that bind and divide them into groups of three, each group should contain one oxygen and two hydrogen threads.</p>
-
-<p>Write synchronization code for oxygen and hydrogen molecules that enforces these constraints.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> water = &quot;HOH&quot;
-<strong>Output:</strong> &quot;HHO&quot;
-<strong>Explanation:</strong> &quot;HOH&quot; and &quot;OHH&quot; are also valid answers.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> water = &quot;OOHHHH&quot;
-<strong>Output:</strong> &quot;HHOHHO&quot;
-<strong>Explanation:</strong> &quot;HOHHHO&quot;, &quot;OHHHHO&quot;, &quot;HHOHOH&quot;, &quot;HOHHOH&quot;, &quot;OHHHOH&quot;, &quot;HHOOHH&quot;, &quot;HOHOHH&quot; and &quot;OHHOHH&quot; are also valid answers.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 * n == water.length</code></li>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-	<li><code>water[i]</code> is either <code>&#39;H&#39;</code> or <code>&#39;O&#39;</code>.</li>
-	<li>There will be exactly <code>2 * n</code> <code>&#39;H&#39;</code> in <code>water</code>.</li>
-	<li>There will be exactly <code>n</code> <code>&#39;O&#39;</code> in <code>water</code>.</li>
-</ul>
-
-### Related Topics
-  [[Concurrency](../../tag/concurrency/README.md)]
diff --git a/problems/building-h2o/building_h2o.py b/problems/building-h2o/building_h2o.py
deleted file mode 100755
index d675daa14..000000000
--- a/problems/building-h2o/building_h2o.py
+++ /dev/null
@@ -1,17 +0,0 @@
-#!/usr/bin/env python
-
-class H2O:
-    def __init__(self):
-        pass
-
-
-    def hydrogen(self, releaseHydrogen: 'Callable[[], None]') -> None:
-        
-        # releaseHydrogen() outputs "H". Do not change or remove this line.
-        releaseHydrogen()
-
-
-    def oxygen(self, releaseOxygen: 'Callable[[], None]') -> None:
-        
-        # releaseOxygen() outputs "O". Do not change or remove this line.
-        releaseOxygen()
\ No newline at end of file
diff --git a/problems/buildings-with-an-ocean-view/README.md b/problems/buildings-with-an-ocean-view/README.md
deleted file mode 100644
index 37792f25e..000000000
--- a/problems/buildings-with-an-ocean-view/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-degree-of-a-connected-trio-in-a-graph "Minimum Degree of a Connected Trio in a Graph")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-nice-substring "Longest Nice Substring")
-
-## [1762. Buildings With an Ocean View (Medium)](https://leetcode.com/problems/buildings-with-an-ocean-view "能看到海景的建筑物")
-
-
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can traverse the buildings from the nearest to the ocean to the furthest.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep with you the maximum to the right while traversing to determine if you can see the ocean or not.
-</details>
diff --git a/problems/bulb-switcher-ii/README.md b/problems/bulb-switcher-ii/README.md
deleted file mode 100644
index c2af65e7a..000000000
--- a/problems/bulb-switcher-ii/README.md
+++ /dev/null
@@ -1,95 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../second-minimum-node-in-a-binary-tree "Second Minimum Node In a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-longest-increasing-subsequence "Number of Longest Increasing Subsequence")
-
-## [672. Bulb Switcher II (Medium)](https://leetcode.com/problems/bulb-switcher-ii "灯泡开关 Ⅱ")
-
-<p>There is a room with <code>n</code> bulbs labeled from <code>1</code> to <code>n</code> that all are turned on initially, and <strong>four buttons</strong> on the wall. Each of the four buttons has a different functionality where:</p>
-
-<ul>
-	<li><strong>Button 1:</strong> Flips the status of all the bulbs.</li>
-	<li><strong>Button 2:</strong> Flips the status of all the bulbs with even labels (i.e., <code>2, 4, ...</code>).</li>
-	<li><strong>Button 3:</strong> Flips the status of all the bulbs with odd labels (i.e., <code>1, 3, ...</code>).</li>
-	<li><strong>Button 4:</strong> Flips the status of all the bulbs with a label <code>j = 3k + 1</code> where <code>k = 0, 1, 2, ...</code> (i.e., <code>1, 4, 7, 10, ...</code>).</li>
-</ul>
-
-<p>You must make <strong>exactly</strong> <code>presses</code> button presses in total. For each press, you may pick <strong>any</strong> of the four buttons to press.</p>
-
-<p>Given the two integers <code>n</code> and <code>presses</code>, return <em>the number of <strong>different possible statuses</strong> after performing all </em><code>presses</code><em> button presses</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, presses = 1
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Status can be:
-- [off] by pressing button 1
-- [on] by pressing button 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, presses = 1
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Status can be:
-- [off, off] by pressing button 1
-- [on, off] by pressing button 2
-- [off, on] by pressing button 3
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, presses = 1
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Status can be:
-- [off, off, off] by pressing button 1
-- [off, on, off] by pressing button 2
-- [on, off, on] by pressing button 3
-- [off, on, on] by pressing button 4
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, presses = 0
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Status can only be [on] since you cannot press any of the buttons.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, presses = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Status can be:
-- [off] by pressing button 1 then button 1 again
-- [on] by pressing button 1 then button 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>0 &lt;= presses &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Bulb Switcher](../bulb-switcher) (Medium)
-  1. [Bulb Switcher III](../bulb-switcher-iii) (Medium)
diff --git a/problems/bulb-switcher-ii/bulb_switcher_ii.go b/problems/bulb-switcher-ii/bulb_switcher_ii.go
deleted file mode 100644
index 37fccc8b5..000000000
--- a/problems/bulb-switcher-ii/bulb_switcher_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem672
diff --git a/problems/bulb-switcher-ii/bulb_switcher_ii_test.go b/problems/bulb-switcher-ii/bulb_switcher_ii_test.go
deleted file mode 100644
index 37fccc8b5..000000000
--- a/problems/bulb-switcher-ii/bulb_switcher_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem672
diff --git a/problems/bulb-switcher-iii/README.md b/problems/bulb-switcher-iii/README.md
deleted file mode 100644
index bc5d0acba..000000000
--- a/problems/bulb-switcher-iii/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../generate-a-string-with-characters-that-have-odd-counts "Generate a String With Characters That Have Odd Counts")
-　　　　　　　　　　　　　　　　
-[Next >](../time-needed-to-inform-all-employees "Time Needed to Inform All Employees")
-
-## [1375. Bulb Switcher III (Medium)](https://leetcode.com/problems/bulb-switcher-iii "灯泡开关 III")
-
-<p>There is a room with <code>n</code> bulbs, numbered from <code>1</code> to <code>n</code>, arranged in a row from left to right. Initially, all the bulbs are turned off.</p>
-
-<p>At moment <code>k</code> (for <code>k</code> from <code>0</code> to <code>n - 1</code>), we turn on the <code>light[k]</code> bulb. A bulb <strong>changes color to blue</strong> only if it is on and all the previous bulbs (to the left) are turned on too.</p>
-
-<p>Return the number of moments in which <strong>all turned-on</strong> bulbs <strong>are blue.</strong></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/29/sample_2_1725.png" style="width: 575px; height: 300px;" />
-<pre>
-<strong>Input:</strong> light = [2,1,3,5,4]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> All bulbs turned on, are blue at the moment 1, 2 and 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> light = [3,2,4,1,5]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> All bulbs turned on, are blue at the moment 3, and 4 (index-0).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> light = [4,1,2,3]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> All bulbs turned on, are blue at the moment 3 (index-0).
-Bulb 4th changes to blue at the moment 3.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> light = [2,1,4,3,6,5]
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> light = [1,2,3,4,5,6]
-<strong>Output:</strong> 6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == light.length</code></li>
-	<li><code>1 &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>light</code> is a permutation of the numbers in the range <code>[1, n]</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Bulb Switcher](../bulb-switcher) (Medium)
-  1. [Bulb Switcher II](../bulb-switcher-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If in the step x all bulb shines then bulbs 1,2,3,..,x should shines too.
-</details>
diff --git a/problems/bulb-switcher-iv/README.md b/problems/bulb-switcher-iv/README.md
deleted file mode 100644
index dfaa2dd4f..000000000
--- a/problems/bulb-switcher-iv/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shuffle-string "Shuffle String")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-good-leaf-nodes-pairs "Number of Good Leaf Nodes Pairs")
-
-## [1529. Bulb Switcher IV (Medium)](https://leetcode.com/problems/bulb-switcher-iv "灯泡开关 IV")
-
-<p>There is a room with <code>n</code> bulbs, numbered from <code>0</code> to <code>n - 1</code>, arranged in a row from left to right. Initially, all the bulbs are <strong>turned off</strong>.</p>
-
-<p>Your task is to obtain the configuration represented by <code>target</code> where <code>target[i]</code> is <code>&#39;1&#39;</code> if the <code>i<sup>th</sup></code> bulb is turned on and is <code>&#39;0&#39;</code> if it is turned off.</p>
-
-<p>You have a switch to flip the state of the bulb, a flip operation is defined as follows:</p>
-
-<ul>
-	<li>Choose <strong>any</strong> bulb (index <code>i</code>) of your current configuration.</li>
-	<li>Flip each bulb from index <code>i</code> to index <code>n - 1</code>.</li>
-</ul>
-
-<p>When any bulb is flipped it means that if it is <code>&#39;0&#39;</code> it changes to <code>&#39;1&#39;</code> and if it is <code>&#39;1&#39;</code> it changes to <code>&#39;0&#39;</code>.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of flips required to form</em> <code>target</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = &quot;10111&quot;
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>Initial configuration &quot;00000&quot;.
-flip from the third bulb:  &quot;00000&quot; -&gt; &quot;00111&quot;
-flip from the first bulb:  &quot;00111&quot; -&gt; &quot;11000&quot;
-flip from the second bulb:  &quot;11000&quot; -&gt; &quot;10111&quot;
-We need at least 3 flip operations to form target.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = &quot;101&quot;
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>&quot;000&quot; -&gt; &quot;111&quot; -&gt; &quot;100&quot; -&gt; &quot;101&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = &quot;00000&quot;
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = &quot;001011101&quot;
-<strong>Output:</strong> 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= target.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>target[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider a strategy where the choice of bulb with number i is increasing. In such a strategy, you no longer need to worry about bulbs that have been set to the left.
-</details>
diff --git a/problems/bulb-switcher/README.md b/problems/bulb-switcher/README.md
deleted file mode 100644
index 646c4a73c..000000000
--- a/problems/bulb-switcher/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-product-of-word-lengths "Maximum Product of Word Lengths")
-　　　　　　　　　　　　　　　　
-[Next >](../generalized-abbreviation "Generalized Abbreviation")
-
-## [319. Bulb Switcher (Medium)](https://leetcode.com/problems/bulb-switcher "灯泡开关")
-
-<p>There are <code>n</code> bulbs that are initially off. You first turn on all the bulbs, then&nbsp;you turn off every second bulb.</p>
-
-<p>On the third round, you toggle every third bulb (turning on if it&#39;s off or turning off if it&#39;s on). For the <code>i<sup>th</sup></code> round, you toggle every <code>i</code> bulb. For the <code>n<sup>th</sup></code> round, you only toggle the last bulb.</p>
-
-<p>Return <em>the number of bulbs that are on after <code>n</code> rounds</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/bulb.jpg" style="width: 421px; height: 321px;" />
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> At first, the three bulbs are [off, off, off].
-After the first round, the three bulbs are [on, on, on].
-After the second round, the three bulbs are [on, off, on].
-After the third round, the three bulbs are [on, off, off]. 
-So you should return 1 because there is only one bulb is on.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Brainteaser](../../tag/brainteaser/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Bulb Switcher II](../bulb-switcher-ii) (Medium)
-  1. [Minimum Number of K Consecutive Bit Flips](../minimum-number-of-k-consecutive-bit-flips) (Hard)
diff --git a/problems/bulb-switcher/bulb_switcher.go b/problems/bulb-switcher/bulb_switcher.go
deleted file mode 100644
index 07da21653..000000000
--- a/problems/bulb-switcher/bulb_switcher.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem319
-
-import "math"
-
-func bulbSwitch(n int) int {
-	return int(math.Sqrt(float64(n)))
-}
diff --git a/problems/bulb-switcher/bulb_switcher_test.go b/problems/bulb-switcher/bulb_switcher_test.go
deleted file mode 100644
index dadcb2c53..000000000
--- a/problems/bulb-switcher/bulb_switcher_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem319
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestBulbSwitch(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   3,
-			want: 1,
-		},
-		{
-			in:   4,
-			want: 2,
-		},
-		{
-			in:   5,
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := bulbSwitch(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/bulls-and-cows/README.md b/problems/bulls-and-cows/README.md
deleted file mode 100644
index 5705946a0..000000000
--- a/problems/bulls-and-cows/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-longest-consecutive-sequence "Binary Tree Longest Consecutive Sequence")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-increasing-subsequence "Longest Increasing Subsequence")
-
-## [299. Bulls and Cows (Medium)](https://leetcode.com/problems/bulls-and-cows "猜数字游戏")
-
-<p>You are playing the <strong><a href="https://en.wikipedia.org/wiki/Bulls_and_Cows" target="_blank">Bulls and Cows</a></strong> game with your friend.</p>
-
-<p>You write down a secret number and ask your friend to guess what the number is. When your friend makes a guess, you provide a hint with the following info:</p>
-
-<ul>
-	<li>The number of &quot;bulls&quot;, which are digits in the guess that are in the correct position.</li>
-	<li>The number of &quot;cows&quot;, which are digits in the guess that are in your secret number but are located in the wrong position. Specifically, the non-bull digits in the guess that could be rearranged such that they become bulls.</li>
-</ul>
-
-<p>Given the secret number <code>secret</code> and your friend&#39;s guess <code>guess</code>, return <em>the hint for your friend&#39;s guess</em>.</p>
-
-<p>The hint should be formatted as <code>&quot;xAyB&quot;</code>, where <code>x</code> is the number of bulls and <code>y</code> is the number of cows. Note that both <code>secret</code> and <code>guess</code> may contain duplicate digits.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> secret = &quot;1807&quot;, guess = &quot;7810&quot;
-<strong>Output:</strong> &quot;1A3B&quot;
-<strong>Explanation:</strong> Bulls are connected with a &#39;|&#39; and cows are underlined:
-&quot;1807&quot;
-  |
-&quot;<u>7</u>8<u>10</u>&quot;</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> secret = &quot;1123&quot;, guess = &quot;0111&quot;
-<strong>Output:</strong> &quot;1A1B&quot;
-<strong>Explanation:</strong> Bulls are connected with a &#39;|&#39; and cows are underlined:
-&quot;1123&quot;        &quot;1123&quot;
-  |      or     |
-&quot;01<u>1</u>1&quot;        &quot;011<u>1</u>&quot;
-Note that only one of the two unmatched 1s is counted as a cow since the non-bull digits can only be rearranged to allow one 1 to be a bull.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> secret = &quot;1&quot;, guess = &quot;0&quot;
-<strong>Output:</strong> &quot;0A0B&quot;
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> secret = &quot;1&quot;, guess = &quot;1&quot;
-<strong>Output:</strong> &quot;1A0B&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= secret.length, guess.length &lt;= 1000</code></li>
-	<li><code>secret.length == guess.length</code></li>
-	<li><code>secret</code> and <code>guess</code> consist of digits only.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
diff --git a/problems/bulls-and-cows/bulls_and_cows.go b/problems/bulls-and-cows/bulls_and_cows.go
deleted file mode 100644
index a58f8c00b..000000000
--- a/problems/bulls-and-cows/bulls_and_cows.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem299
diff --git a/problems/bulls-and-cows/bulls_and_cows_test.go b/problems/bulls-and-cows/bulls_and_cows_test.go
deleted file mode 100644
index a58f8c00b..000000000
--- a/problems/bulls-and-cows/bulls_and_cows_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem299
diff --git a/problems/burst-balloons/README.md b/problems/burst-balloons/README.md
deleted file mode 100644
index d8143c649..000000000
--- a/problems/burst-balloons/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sparse-matrix-multiplication "Sparse Matrix Multiplication")
-　　　　　　　　　　　　　　　　
-[Next >](../super-ugly-number "Super Ugly Number")
-
-## [312. Burst Balloons (Hard)](https://leetcode.com/problems/burst-balloons "戳气球")
-
-<p>You are given <code>n</code> balloons, indexed from <code>0</code> to <code>n - 1</code>. Each balloon is painted with a number on it represented by an array <code>nums</code>. You are asked to burst all the balloons.</p>
-
-<p>If you burst the <code>i<sup>th</sup></code> balloon, you will get <code>nums[i - 1] * nums[i] * nums[i + 1]</code> coins. If <code>i - 1</code> or <code>i + 1</code> goes out of bounds of the array, then treat it as if there is a balloon with a <code>1</code> painted on it.</p>
-
-<p>Return <em>the maximum coins you can collect by bursting the balloons wisely</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,5,8]
-<strong>Output:</strong> 167
-<strong>Explanation:</strong>
-nums = [3,1,5,8] --&gt; [3,5,8] --&gt; [3,8] --&gt; [8] --&gt; []
-coins =  3*1*5    +   3*5*8   +  1*3*8  + 1*8*1 = 167</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5]
-<strong>Output:</strong> 10
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 300</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Minimum Cost to Merge Stones](../minimum-cost-to-merge-stones) (Hard)
diff --git a/problems/burst-balloons/burst_balloons.go b/problems/burst-balloons/burst_balloons.go
deleted file mode 100644
index 640cbfbb8..000000000
--- a/problems/burst-balloons/burst_balloons.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem312
diff --git a/problems/burst-balloons/burst_balloons_test.go b/problems/burst-balloons/burst_balloons_test.go
deleted file mode 100644
index 640cbfbb8..000000000
--- a/problems/burst-balloons/burst_balloons_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem312
diff --git a/problems/bus-routes/README.md b/problems/bus-routes/README.md
deleted file mode 100644
index 8be99bf69..000000000
--- a/problems/bus-routes/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-pruning "Binary Tree Pruning")
-　　　　　　　　　　　　　　　　
-[Next >](../ambiguous-coordinates "Ambiguous Coordinates")
-
-## [815. Bus Routes (Hard)](https://leetcode.com/problems/bus-routes "公交路线")
-
-<p>You are given an array <code>routes</code> representing bus routes where <code>routes[i]</code> is a bus route that the <code>i<sup>th</sup></code> bus repeats forever.</p>
-
-<ul>
-	<li>For example, if <code>routes[0] = [1, 5, 7]</code>, this means that the <code>0<sup>th</sup></code> bus travels in the sequence <code>1 -&gt; 5 -&gt; 7 -&gt; 1 -&gt; 5 -&gt; 7 -&gt; 1 -&gt; ...</code> forever.</li>
-</ul>
-
-<p>You will start at the bus stop <code>source</code> (You are not on any bus initially), and you want to go to the bus stop <code>target</code>. You can travel between bus stops by buses only.</p>
-
-<p>Return <em>the least number of buses you must take to travel from </em><code>source</code><em> to </em><code>target</code>. Return <code>-1</code> if it is not possible.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> routes = [[1,2,7],[3,6,7]], source = 1, target = 6
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The best strategy is take the first bus to the bus stop 7, then take the second bus to the bus stop 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> routes = [[7,12],[4,5,15],[6],[15,19],[9,12,13]], source = 15, target = 12
-<strong>Output:</strong> -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= routes.length &lt;= 500</code>.</li>
-	<li><code>1 &lt;= routes[i].length &lt;= 10<sup>5</sup></code></li>
-	<li>All the values of <code>routes[i]</code> are <strong>unique</strong>.</li>
-	<li><code>sum(routes[i].length) &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= routes[i][j] &lt; 10<sup>6</sup></code></li>
-	<li><code>0 &lt;= source, target &lt; 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
diff --git a/problems/bus-routes/bus_routes.go b/problems/bus-routes/bus_routes.go
deleted file mode 100644
index 9bf0252e8..000000000
--- a/problems/bus-routes/bus_routes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem815
diff --git a/problems/bus-routes/bus_routes_test.go b/problems/bus-routes/bus_routes_test.go
deleted file mode 100644
index 9bf0252e8..000000000
--- a/problems/bus-routes/bus_routes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem815
diff --git a/problems/calculate-money-in-leetcode-bank/README.md b/problems/calculate-money-in-leetcode-bank/README.md
deleted file mode 100644
index 7f70f38b2..000000000
--- a/problems/calculate-money-in-leetcode-bank/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-apples-and-oranges "Count Apples and Oranges")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-score-from-removing-substrings "Maximum Score From Removing Substrings")
-
-## [1716. Calculate Money in Leetcode Bank (Easy)](https://leetcode.com/problems/calculate-money-in-leetcode-bank "计算力扣银行的钱")
-
-<p>Hercy wants to save money for his first car. He puts money in the Leetcode&nbsp;bank <strong>every day</strong>.</p>
-
-<p>He starts by putting in <code>$1</code> on Monday, the first day. Every day from Tuesday to Sunday, he will put in <code>$1</code> more than the day before. On every subsequent Monday, he will put in <code>$1</code> more than the <strong>previous Monday</strong>.<span style="display: none;"> </span></p>
-
-<p>Given <code>n</code>, return <em>the total amount of money he will have in the Leetcode bank at the end of the </em><code>n<sup>th</sup></code><em> day.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 10
-<strong>Explanation:</strong>&nbsp;After the 4<sup>th</sup> day, the total is 1 + 2 + 3 + 4 = 10.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 37
-<strong>Explanation:</strong>&nbsp;After the 10<sup>th</sup> day, the total is (1 + 2 + 3 + 4 + 5 + 6 + 7) + (2 + 3 + 4) = 37. Notice that on the 2<sup>nd</sup> Monday, Hercy only puts in $2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 20
-<strong>Output:</strong> 96
-<strong>Explanation:</strong>&nbsp;After the 20<sup>th</sup> day, the total is (1 + 2 + 3 + 4 + 5 + 6 + 7) + (2 + 3 + 4 + 5 + 6 + 7 + 8) + (3 + 4 + 5 + 6 + 7 + 8) = 96.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process by keeping track of how much money John is putting in and which day of the week it is, and use this information to deduce how much money John will put in the next day.
-</details>
diff --git a/problems/calculate-salaries/README.md b/problems/calculate-salaries/README.md
deleted file mode 100644
index 9f0654cc5..000000000
--- a/problems/calculate-salaries/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../probability-of-a-two-boxes-having-the-same-number-of-distinct-balls "Probability of a Two Boxes Having The Same Number of Distinct Balls")
-　　　　　　　　　　　　　　　　
-[Next >](../find-all-the-lonely-nodes "Find All The Lonely Nodes")
-
-## [1468. Calculate Salaries (Medium)](https://leetcode.com/problems/calculate-salaries "计算税后工资")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/calculate-salaries/mysql_schemas.sql b/problems/calculate-salaries/mysql_schemas.sql
deleted file mode 100644
index a60a565aa..000000000
--- a/problems/calculate-salaries/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Salaries (company_id int, employee_id int, employee_name varchar(13), salary int);
-Truncate table Salaries;
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('1', '1', 'Tony', '2000');
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('1', '2', 'Pronub', '21300');
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('1', '3', 'Tyrrox', '10800');
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('2', '1', 'Pam', '300');
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('2', '7', 'Bassem', '450');
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('2', '9', 'Hermione', '700');
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('3', '7', 'Bocaben', '100');
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('3', '2', 'Ognjen', '2200');
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('3', '13', 'Nyancat', '3300');
-insert into Salaries (company_id, employee_id, employee_name, salary) values ('3', '15', 'Morninngcat', '7777');
diff --git a/problems/calculate-special-bonus/README.md b/problems/calculate-special-bonus/README.md
deleted file mode 100644
index 1fdb4c0d3..000000000
--- a/problems/calculate-special-bonus/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stone-game-viii "Stone Game VIII")
-　　　　　　　　　　　　　　　　
-[Next >](../minimize-product-sum-of-two-arrays "Minimize Product Sum of Two Arrays")
-
-## [1873. Calculate Special Bonus (Easy)](https://leetcode.com/problems/calculate-special-bonus "计算特殊奖金")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/calculate-special-bonus/mysql_schemas.sql b/problems/calculate-special-bonus/mysql_schemas.sql
deleted file mode 100644
index d5d505e6f..000000000
--- a/problems/calculate-special-bonus/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Employees (employee_id int, name varchar(30), salary int);
-Truncate table Employees;
-insert into Employees (employee_id, name, salary) values ('2', 'Meir', '3000');
-insert into Employees (employee_id, name, salary) values ('3', 'Michael', '3800');
-insert into Employees (employee_id, name, salary) values ('7', 'Addilyn', '7400');
-insert into Employees (employee_id, name, salary) values ('8', 'Juan', '6100');
-insert into Employees (employee_id, name, salary) values ('9', 'Kannon', '7700');
diff --git a/problems/camelcase-matching/README.md b/problems/camelcase-matching/README.md
deleted file mode 100644
index 3d40dd3c7..000000000
--- a/problems/camelcase-matching/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-root-to-leaf-binary-numbers "Sum of Root To Leaf Binary Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../video-stitching "Video Stitching")
-
-## [1023. Camelcase Matching (Medium)](https://leetcode.com/problems/camelcase-matching "驼峰式匹配")
-
-<p>Given an array of strings <code>queries</code> and a string <code>pattern</code>, return a boolean array <code>answer</code> where <code>answer[i]</code> is <code>true</code> if <code>queries[i]</code> matches <code>pattern</code>, and <code>false</code> otherwise.</p>
-
-<p>A query word <code>queries[i]</code> matches <code>pattern</code> if you can insert lowercase English letters pattern so that it equals the query. You may insert each character at any position and you may not insert any characters.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [&quot;FooBar&quot;,&quot;FooBarTest&quot;,&quot;FootBall&quot;,&quot;FrameBuffer&quot;,&quot;ForceFeedBack&quot;], pattern = &quot;FB&quot;
-<strong>Output:</strong> [true,false,true,true,false]
-<strong>Explanation:</strong> &quot;FooBar&quot; can be generated like this &quot;F&quot; + &quot;oo&quot; + &quot;B&quot; + &quot;ar&quot;.
-&quot;FootBall&quot; can be generated like this &quot;F&quot; + &quot;oot&quot; + &quot;B&quot; + &quot;all&quot;.
-&quot;FrameBuffer&quot; can be generated like this &quot;F&quot; + &quot;rame&quot; + &quot;B&quot; + &quot;uffer&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [&quot;FooBar&quot;,&quot;FooBarTest&quot;,&quot;FootBall&quot;,&quot;FrameBuffer&quot;,&quot;ForceFeedBack&quot;], pattern = &quot;FoBa&quot;
-<strong>Output:</strong> [true,false,true,false,false]
-<strong>Explanation:</strong> &quot;FooBar&quot; can be generated like this &quot;Fo&quot; + &quot;o&quot; + &quot;Ba&quot; + &quot;r&quot;.
-&quot;FootBall&quot; can be generated like this &quot;Fo&quot; + &quot;ot&quot; + &quot;Ba&quot; + &quot;ll&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [&quot;FooBar&quot;,&quot;FooBarTest&quot;,&quot;FootBall&quot;,&quot;FrameBuffer&quot;,&quot;ForceFeedBack&quot;], pattern = &quot;FoBaT&quot;
-<strong>Output:</strong> [false,true,false,false,false]
-<strong>Explanation:</strong> &quot;FooBarTest&quot; can be generated like this &quot;Fo&quot; + &quot;o&quot; + &quot;Ba&quot; + &quot;r&quot; + &quot;T&quot; + &quot;est&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= pattern.length, queries.length &lt;= 100</code></li>
-	<li><code>1 &lt;= queries[i].length &lt;= 100</code></li>
-	<li><code>queries[i]</code> and <code>pattern</code> consist of English letters.</li>
-</ul>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given a single pattern and word, how can we solve it?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-One way to do it is using a DP (pos1, pos2) where pos1 is a pointer to the word and pos2 to the pattern and returns true if we can match the pattern with the given word.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We have two scenarios: The first one is when `word[pos1] == pattern[pos2]`, then the transition will be just DP(pos1 + 1, pos2 + 1). The second scenario is when `word[pos1]` is lowercase then we can add this character to the pattern so that the transition is just DP(pos1 + 1, pos2)
-The case base is `if (pos1 == n && pos2 == m) return true;` Where n and m are the sizes of the strings word and pattern respectively.
-</details>
diff --git a/problems/camelcase-matching/camelcase_matching.go b/problems/camelcase-matching/camelcase_matching.go
deleted file mode 100644
index a4af3e89b..000000000
--- a/problems/camelcase-matching/camelcase_matching.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem1023
-
-func camelMatch(queries []string, pattern string) []bool {
-	ans := make([]bool, len(queries))
-	for i, q := range queries {
-		ptn := []rune(pattern)
-		for _, r := range q {
-			if len(ptn) > 0 && ptn[0] == r {
-				ptn = ptn[1:]
-			} else if r >= 'A' && r <= 'Z' {
-				ptn = []rune{1}
-				break
-			}
-		}
-		ans[i] = len(ptn) == 0
-	}
-	return ans
-}
diff --git a/problems/camelcase-matching/camelcase_matching_test.go b/problems/camelcase-matching/camelcase_matching_test.go
deleted file mode 100644
index 550fd2226..000000000
--- a/problems/camelcase-matching/camelcase_matching_test.go
+++ /dev/null
@@ -1,48 +0,0 @@
-package problem1023
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	queries []string
-	pattern string
-	want    []bool
-}
-
-func TestCamelMatch(t *testing.T) {
-	tests := [...]testType{
-		{
-			queries: []string{"FooBar", "FooBarTest", "FootBall", "FrameBuffer", "ForceFeedBack"},
-			pattern: "FB",
-			want:    []bool{true, false, true, true, false},
-		},
-		{
-			queries: []string{"FooBar", "FooBarTest", "FootBall", "FrameBuffer", "ForceFeedBack"},
-			pattern: "FoBa",
-			want:    []bool{true, false, true, false, false},
-		},
-		{
-			queries: []string{"FooBar", "FooBarTest", "FootBall", "FrameBuffer", "ForceFeedBack"},
-			pattern: "FoBaT",
-			want:    []bool{false, true, false, false, false},
-		},
-		{
-			queries: []string{"CompetitiveProgramming", "CounterPick", "ControlPanel"},
-			pattern: "CooP",
-			want:    []bool{false, false, true},
-		},
-		{
-			queries: []string{"aksvbjLiknuTzqon", "ksvjLimflkpnTzqn", "mmkasvjLiknTxzqn", "ksvjLiurknTzzqbn", "ksvsjLctikgnTzqn", "knzsvzjLiknTszqn"},
-			pattern: "ksvjLiknTzqn",
-			want:    []bool{true, true, true, true, true, true},
-		},
-	}
-	for _, tt := range tests {
-		got := camelMatch(tt.queries, tt.pattern)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.pattern, got, tt.want)
-		}
-	}
-}
diff --git a/problems/campus-bikes-ii/README.md b/problems/campus-bikes-ii/README.md
deleted file mode 100644
index e75cc52fc..000000000
--- a/problems/campus-bikes-ii/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../index-pairs-of-a-string "Index Pairs of a String")
-　　　　　　　　　　　　　　　　
-[Next >](../digit-count-in-range "Digit Count in Range")
-
-## [1066. Campus Bikes II (Medium)](https://leetcode.com/problems/campus-bikes-ii "校园自行车分配 II")
-
-<p>On a campus represented as a 2D grid, there are <code>N</code> workers and <code>M</code> bikes, with <code>N &lt;= M</code>. Each worker and bike is a 2D coordinate on this grid.</p>
-
-<p>We assign one unique bike to each worker so that the sum of the Manhattan distances between each worker and their assigned bike is minimized.</p>
-
-<p>The Manhattan distance between two points <code>p1</code> and <code>p2</code> is <code>Manhattan(p1, p2) = |p1.x - p2.x| + |p1.y - p2.y|</code>.</p>
-
-<p>Return the minimum possible sum of Manhattan distances between each worker and their assigned bike.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/06/1261_example_1_v2.png" style="width: 264px; height: 264px;" /></p>
-
-<pre>
-<strong>Input: </strong>workers = <span id="example-input-1-1">[[0,0],[2,1]]</span>, bikes = <span id="example-input-1-2">[[1,2],[3,3]]</span>
-<strong>Output: </strong><span id="example-output-1">6</span>
-<strong>Explanation: </strong>
-We assign bike 0 to worker 0, bike 1 to worker 1. The Manhattan distance of both assignments is 3, so the output is 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/06/1261_example_2_v2.png" style="width: 264px; height: 264px;" /></p>
-
-<pre>
-<strong>Input: </strong>workers = <span id="example-input-2-1">[[0,0],[1,1],[2,0]]</span>, bikes = <span id="example-input-2-2">[[1,0],[2,2],[2,1]]</span>
-<strong>Output: </strong><span id="example-output-2">4</span>
-<strong>Explanation: </strong>
-We first assign bike 0 to worker 0, then assign bike 1 to worker 1 or worker 2, bike 2 to worker 2 or worker 1. Both assignments lead to sum of the Manhattan distances as 4.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>0 &lt;= workers[i][0], workers[i][1], bikes[i][0], bikes[i][1] &lt; 1000</code></li>
-	<li>All worker and bike locations are distinct.</li>
-	<li><code>1 &lt;= workers.length &lt;= bikes.length &lt;= 10</code></li>
-</ol>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Similar Questions
-  1. [Campus Bikes](../campus-bikes) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Model the problem with a dp(pos, mask) where pos represents the current bike to be assigned and mask the set of available workers.
-</details>
diff --git a/problems/campus-bikes/README.md b/problems/campus-bikes/README.md
deleted file mode 100644
index 6e99c5415..000000000
--- a/problems/campus-bikes/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../confusing-number "Confusing Number")
-　　　　　　　　　　　　　　　　
-[Next >](../minimize-rounding-error-to-meet-target "Minimize Rounding Error to Meet Target")
-
-## [1057. Campus Bikes (Medium)](https://leetcode.com/problems/campus-bikes "校园自行车分配")
-
-<p>On a campus represented as a 2D grid, there are <code>N</code> workers and <code>M</code> bikes, with <code>N &lt;= M</code>. Each worker and bike is a 2D coordinate on this grid.</p>
-
-<p>Our goal is to assign a bike to each worker. Among the available bikes and workers, we choose the (worker, bike) pair with the shortest Manhattan distance between each other, and assign the bike to that worker. (If there are multiple (worker, bike) pairs with the same shortest Manhattan distance, we choose the pair with the smallest worker index; if there are multiple ways to do that, we choose the pair with the smallest bike index). We repeat this process until there are no available workers.</p>
-
-<p>The Manhattan distance between two points <code>p1</code> and <code>p2</code> is <code>Manhattan(p1, p2) = |p1.x - p2.x| + |p1.y - p2.y|</code>.</p>
-
-<p>Return a vector <code>ans</code> of length <code>N</code>, where <code>ans[i]</code> is the index (0-indexed) of the bike that the <code>i</code>-th worker is assigned to.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/06/1261_example_1_v2.png" style="width: 264px; height: 264px;" /></p>
-
-<pre>
-<strong>Input: </strong>workers = <span id="example-input-1-1">[[0,0],[2,1]]</span>, bikes = <span id="example-input-1-2">[[1,2],[3,3]]</span>
-<strong>Output: </strong><span id="example-output-1">[1,0]</span>
-<strong>Explanation: </strong>
-Worker 1 grabs Bike 0 as they are closest (without ties), and Worker 0 is assigned Bike 1. So the output is [1, 0].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/06/1261_example_2_v2.png" style="width: 264px; height: 264px;" /></p>
-
-<pre>
-<strong>Input: </strong>workers = <span id="example-input-2-1">[[0,0],[1,1],[2,0]]</span>, bikes = <span id="example-input-2-2">[[1,0],[2,2],[2,1]]</span>
-<strong>Output: </strong><span id="example-output-2">[0,2,1]</span>
-<strong>Explanation: </strong>
-Worker 0 grabs Bike 0 at first. Worker 1 and Worker 2 share the same distance to Bike 2, thus Worker 1 is assigned to Bike 2, and Worker 2 will take Bike 1. So the output is [0,2,1].
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>0 &lt;= workers[i][j], bikes[i][j] &lt; 1000</code></li>
-	<li>All worker and bike locations are distinct.</li>
-	<li><code>1 &lt;= workers.length &lt;= bikes.length &lt;= 1000</code></li>
-</ol>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Campus Bikes II](../campus-bikes-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-<p>Sort the elements by distance. In case of a tie, sort them by the index of the worker. After that, if there are still ties, sort them by the index of the bike.</p>
-
-<p>Can you do this in less than O(nlogn) time, where n is the total number of pairs between workers and bikes?</p>
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop the sorted elements and match each pair of worker and bike if the given worker and bike where not used.
-</details>
diff --git a/problems/can-convert-string-in-k-moves/README.md b/problems/can-convert-string-in-k-moves/README.md
deleted file mode 100644
index 38ce7036e..000000000
--- a/problems/can-convert-string-in-k-moves/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-missing-positive-number "Kth Missing Positive Number")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-insertions-to-balance-a-parentheses-string "Minimum Insertions to Balance a Parentheses String")
-
-## [1540. Can Convert String in K Moves (Medium)](https://leetcode.com/problems/can-convert-string-in-k-moves "K 次操作转变字符串")
-
-<p>Given two strings&nbsp;<code>s</code>&nbsp;and&nbsp;<code>t</code>, your goal is to convert&nbsp;<code>s</code>&nbsp;into&nbsp;<code>t</code>&nbsp;in&nbsp;<code>k</code><strong>&nbsp;</strong>moves or less.</p>
-
-<p>During the&nbsp;<code>i<sup>th</sup></code>&nbsp;(<font face="monospace"><code>1 &lt;= i &lt;= k</code>)&nbsp;</font>move you can:</p>
-
-<ul>
-	<li>Choose any index&nbsp;<code>j</code>&nbsp;(1-indexed) from&nbsp;<code>s</code>, such that&nbsp;<code>1 &lt;= j &lt;= s.length</code>&nbsp;and <code>j</code>&nbsp;has not been chosen in any previous move,&nbsp;and shift the character at that index&nbsp;<code>i</code>&nbsp;times.</li>
-	<li>Do nothing.</li>
-</ul>
-
-<p>Shifting a character means replacing it by the next letter in the alphabet&nbsp;(wrapping around so that&nbsp;<code>&#39;z&#39;</code>&nbsp;becomes&nbsp;<code>&#39;a&#39;</code>). Shifting a character by&nbsp;<code>i</code>&nbsp;means applying the shift operations&nbsp;<code>i</code>&nbsp;times.</p>
-
-<p>Remember that any index&nbsp;<code>j</code>&nbsp;can be picked at most once.</p>
-
-<p>Return&nbsp;<code>true</code>&nbsp;if it&#39;s possible to convert&nbsp;<code>s</code>&nbsp;into&nbsp;<code>t</code>&nbsp;in no more than&nbsp;<code>k</code>&nbsp;moves, otherwise return&nbsp;<code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;input&quot;, t = &quot;ouput&quot;, k = 9
-<strong>Output:</strong> true
-<b>Explanation: </b>In the 6th move, we shift &#39;i&#39; 6 times to get &#39;o&#39;. And in the 7th move we shift &#39;n&#39; to get &#39;u&#39;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;, t = &quot;bcd&quot;, k = 10
-<strong>Output:</strong> false
-<strong>Explanation: </strong>We need to shift each character in s one time to convert it into t. We can shift &#39;a&#39; to &#39;b&#39; during the 1st move. However, there is no way to shift the other characters in the remaining moves to obtain t from s.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aab&quot;, t = &quot;bbb&quot;, k = 27
-<strong>Output:</strong> true
-<b>Explanation: </b>In the 1st move, we shift the first &#39;a&#39; 1 time to get &#39;b&#39;. In the 27th move, we shift the second &#39;a&#39; 27 times to get &#39;b&#39;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, t.length &lt;= 10^5</code></li>
-	<li><code>0 &lt;= k &lt;= 10^9</code></li>
-	<li><code>s</code>, <code>t</code> contain&nbsp;only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Observe that shifting a letter x times has the same effect of shifting the letter x + 26 times.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You need to check whether k is large enough to cover all shifts with the same remainder after modulo 26.
-</details>
diff --git a/problems/can-i-win/README.md b/problems/can-i-win/README.md
deleted file mode 100644
index dd4163c8a..000000000
--- a/problems/can-i-win/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../island-perimeter "Island Perimeter")
-　　　　　　　　　　　　　　　　
-[Next >](../optimal-account-balancing "Optimal Account Balancing")
-
-## [464. Can I Win (Medium)](https://leetcode.com/problems/can-i-win "我能赢吗")
-
-<p>In the &quot;100 game&quot; two players take turns adding, to a running total, any integer from <code>1</code> to <code>10</code>. The player who first causes the running total to <strong>reach or exceed</strong> 100 wins.</p>
-
-<p>What if we change the game so that players <strong>cannot</strong> re-use integers?</p>
-
-<p>For example, two players might take turns drawing from a common pool of numbers from 1 to 15 without replacement until they reach a total &gt;= 100.</p>
-
-<p>Given two integers <code>maxChoosableInteger</code> and <code>desiredTotal</code>, return <code>true</code> if the first player to move can force a win, otherwise, return <code>false</code>. Assume both players play <strong>optimally</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> maxChoosableInteger = 10, desiredTotal = 11
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-No matter which integer the first player choose, the first player will lose.
-The first player can choose an integer from 1 up to 10.
-If the first player choose 1, the second player can only choose integers from 2 up to 10.
-The second player will win by choosing 10 and get a total = 11, which is &gt;= desiredTotal.
-Same with other integers chosen by the first player, the second player will always win.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> maxChoosableInteger = 10, desiredTotal = 0
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> maxChoosableInteger = 10, desiredTotal = 1
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= maxChoosableInteger &lt;= 20</code></li>
-	<li><code>0 &lt;= desiredTotal &lt;= 300</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Similar Questions
-  1. [Flip Game II](../flip-game-ii) (Medium)
-  1. [Guess Number Higher or Lower II](../guess-number-higher-or-lower-ii) (Medium)
-  1. [Predict the Winner](../predict-the-winner) (Medium)
diff --git a/problems/can-i-win/can_i_win.go b/problems/can-i-win/can_i_win.go
deleted file mode 100644
index cf9f28b20..000000000
--- a/problems/can-i-win/can_i_win.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem464
diff --git a/problems/can-i-win/can_i_win_test.go b/problems/can-i-win/can_i_win_test.go
deleted file mode 100644
index cf9f28b20..000000000
--- a/problems/can-i-win/can_i_win_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem464
diff --git a/problems/can-make-arithmetic-progression-from-sequence/README.md b/problems/can-make-arithmetic-progression-from-sequence/README.md
deleted file mode 100644
index 8ab8e871e..000000000
--- a/problems/can-make-arithmetic-progression-from-sequence/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../countries-you-can-safely-invest-in "Countries You Can Safely Invest In")
-　　　　　　　　　　　　　　　　
-[Next >](../last-moment-before-all-ants-fall-out-of-a-plank "Last Moment Before All Ants Fall Out of a Plank")
-
-## [1502. Can Make Arithmetic Progression From Sequence (Easy)](https://leetcode.com/problems/can-make-arithmetic-progression-from-sequence "判断能否形成等差数列")
-
-<p>A sequence of numbers is called an <strong>arithmetic progression</strong> if the difference between any two consecutive elements is the same.</p>
-
-<p>Given an array of numbers <code>arr</code>, return <code>true</code> <em>if the array can be rearranged to form an <strong>arithmetic progression</strong>. Otherwise, return</em> <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,5,1]
-<strong>Output:</strong> true
-<strong>Explanation: </strong>We can reorder the elements as [1,3,5] or [5,3,1] with differences 2 and -2 respectively, between each consecutive elements.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,4]
-<strong>Output:</strong> false
-<strong>Explanation: </strong>There is no way to reorder the elements to obtain an arithmetic progression.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>-10<sup>6</sup> &lt;= arr[i] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Arithmetic Subarrays](../arithmetic-subarrays) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider that any valid arithmetic progression will be in sorted order.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort the array, then check if the differences of all consecutive elements are equal.
-</details>
diff --git a/problems/can-make-palindrome-from-substring/README.md b/problems/can-make-palindrome-from-substring/README.md
deleted file mode 100644
index 20ea8a9eb..000000000
--- a/problems/can-make-palindrome-from-substring/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../diet-plan-performance "Diet Plan Performance")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-valid-words-for-each-puzzle "Number of Valid Words for Each Puzzle")
-
-## [1177. Can Make Palindrome from Substring (Medium)](https://leetcode.com/problems/can-make-palindrome-from-substring "构建回文串检测")
-
-<p>You are given a string <code>s</code> and array <code>queries</code> where <code>queries[i] = [left<sub>i</sub>, right<sub>i</sub>, k<sub>i</sub>]</code>. We may rearrange the substring <code>s[left<sub>i</sub>...right<sub>i</sub>]</code> for each query and then choose up to <code>k<sub>i</sub></code> of them to replace with any lowercase English letter.</p>
-
-<p>If the substring is possible to be a palindrome string after the operations above, the result of the query is <code>true</code>. Otherwise, the result is <code>false</code>.</p>
-
-<p>Return a boolean array <code>answer</code> where <code>answer[i]</code> is the result of the <code>i<sup>th</sup></code> query <code>queries[i]</code>.</p>
-
-<p>Note that each letter is counted individually for replacement, so if, for example <code>s[left<sub>i</sub>...right<sub>i</sub>] = &quot;aaa&quot;</code>, and <code>k<sub>i</sub> = 2</code>, we can only replace two of the letters. Also, note that no query modifies the initial string <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example :</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcda&quot;, queries = [[3,3,0],[1,2,0],[0,3,1],[0,3,2],[0,4,1]]
-<strong>Output:</strong> [true,false,false,true,true]
-<strong>Explanation:</strong>
-queries[0]: substring = &quot;d&quot;, is palidrome.
-queries[1]: substring = &quot;bc&quot;, is not palidrome.
-queries[2]: substring = &quot;abcd&quot;, is not palidrome after replacing only 1 character.
-queries[3]: substring = &quot;abcd&quot;, could be changed to &quot;abba&quot; which is palidrome. Also this can be changed to &quot;baab&quot; first rearrange it &quot;bacd&quot; then replace &quot;cd&quot; with &quot;ab&quot;.
-queries[4]: substring = &quot;abcda&quot;, could be changed to &quot;abcba&quot; which is palidrome.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;lyb&quot;, queries = [[0,1,0],[2,2,1]]
-<strong>Output:</strong> [false,true]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, queries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= left<sub>i</sub> &lt;= right<sub>i</sub> &lt; s.length</code></li>
-	<li><code>0 &lt;= k<sub>i</sub> &lt;= s.length</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since we can rearrange the substring, all we care about is the frequency of each character in that substring.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How to find the character frequencies efficiently ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-As a preprocess, calculate the accumulate frequency of all characters for all prefixes of the string.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-How to check if a substring can be changed to a palindrome given its characters frequency ?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Count the number of odd frequencies, there can be at most one odd frequency in a palindrome.
-</details>
diff --git a/problems/can-place-flowers/README.md b/problems/can-place-flowers/README.md
deleted file mode 100644
index 2cf0c8bdd..000000000
--- a/problems/can-place-flowers/README.md
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-compressed-string-iterator "Design Compressed String Iterator")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-string-from-binary-tree "Construct String from Binary Tree")
-
-## [605. Can Place Flowers (Easy)](https://leetcode.com/problems/can-place-flowers "种花问题")
-
-<p>You have a long flowerbed in which some of the plots are planted, and some are not. However, flowers cannot be planted in <strong>adjacent</strong> plots.</p>
-
-<p>Given an integer array <code>flowerbed</code> containing <code>0</code>&#39;s and <code>1</code>&#39;s, where <code>0</code> means empty and <code>1</code> means not empty, and an integer <code>n</code>, return <em>if</em> <code>n</code> new flowers can be planted in the <code>flowerbed</code> without violating the no-adjacent-flowers rule.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> flowerbed = [1,0,0,0,1], n = 1
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> flowerbed = [1,0,0,0,1], n = 2
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= flowerbed.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>flowerbed[i]</code> is <code>0</code> or <code>1</code>.</li>
-	<li>There are no two adjacent flowers in <code>flowerbed</code>.</li>
-	<li><code>0 &lt;= n &lt;= flowerbed.length</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Teemo Attacking](../teemo-attacking) (Easy)
-  1. [Asteroid Collision](../asteroid-collision) (Medium)
diff --git a/problems/can-place-flowers/can_place_flowers.go b/problems/can-place-flowers/can_place_flowers.go
deleted file mode 100644
index e77cd1faa..000000000
--- a/problems/can-place-flowers/can_place_flowers.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem605
-
-func canPlaceFlowers(flowerbed []int, n int) bool {
-	sum, ec := 0, 1
-	for _, v := range flowerbed {
-		if v == 0 {
-			ec++
-		} else {
-			sum += (ec - 1) / 2
-			ec = 0
-		}
-	}
-	sum += ec / 2
-	return sum >= n
-}
diff --git a/problems/can-place-flowers/can_place_flowers_test.go b/problems/can-place-flowers/can_place_flowers_test.go
deleted file mode 100644
index f3a5097bc..000000000
--- a/problems/can-place-flowers/can_place_flowers_test.go
+++ /dev/null
@@ -1,70 +0,0 @@
-package problem605
-
-import "testing"
-
-type testType struct {
-	flowerbed []int
-	n         int
-	want      bool
-}
-
-func TestCanPlaceFlowers(t *testing.T) {
-	tests := [...]testType{
-		{
-			flowerbed: []int{0, 1, 0, 0, 0, 0, 1, 0},
-			n:         2,
-			want:      false,
-		},
-		{
-			flowerbed: []int{1, 0, 0, 0, 1},
-			n:         1,
-			want:      true,
-		},
-		{
-			flowerbed: []int{1, 0, 0, 0, 1},
-			n:         2,
-			want:      false,
-		},
-		{
-			flowerbed: []int{0, 0, 1, 0},
-			n:         1,
-			want:      true,
-		},
-		{
-			flowerbed: []int{0, 1, 0, 0},
-			n:         1,
-			want:      true,
-		},
-		{
-			flowerbed: []int{0, 1, 0, 0, 1, 0},
-			n:         1,
-			want:      false,
-		},
-		{
-			flowerbed: []int{0, 0, 0, 0, 0},
-			n:         3,
-			want:      true,
-		},
-		{
-			flowerbed: []int{0, 0},
-			n:         2,
-			want:      false,
-		},
-		{
-			flowerbed: []int{0},
-			n:         1,
-			want:      true,
-		},
-		{
-			flowerbed: []int{0, 1},
-			n:         1,
-			want:      false,
-		},
-	}
-	for _, tt := range tests {
-		got := canPlaceFlowers(tt.flowerbed, tt.n)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.flowerbed, tt.n, got, tt.want)
-		}
-	}
-}
diff --git a/problems/can-you-eat-your-favorite-candy-on-your-favorite-day/README.md b/problems/can-you-eat-your-favorite-candy-on-your-favorite-day/README.md
deleted file mode 100644
index ea7291af7..000000000
--- a/problems/can-you-eat-your-favorite-candy-on-your-favorite-day/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../restore-the-array-from-adjacent-pairs "Restore the Array From Adjacent Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-partitioning-iv "Palindrome Partitioning IV")
-
-## [1744. Can You Eat Your Favorite Candy on Your Favorite Day? (Medium)](https://leetcode.com/problems/can-you-eat-your-favorite-candy-on-your-favorite-day "你能在你最喜欢的那天吃到你最喜欢的糖果吗？")
-
-<p>You are given a <strong>(0-indexed)</strong> array of positive integers <code>candiesCount</code> where <code>candiesCount[i]</code> represents the number of candies of the&nbsp;<code>i<sup>th</sup></code>&nbsp;type you have. You are also given a 2D array <code>queries</code> where <code>queries[i] = [favoriteType<sub>i</sub>, favoriteDay<sub>i</sub>, dailyCap<sub>i</sub>]</code>.</p>
-
-<p>You play a game with the following rules:</p>
-
-<ul>
-	<li>You start eating candies on day <code><strong>0</strong></code>.</li>
-	<li>You <b>cannot</b> eat <strong>any</strong> candy of type <code>i</code> unless you have eaten <strong>all</strong> candies of type <code>i - 1</code>.</li>
-	<li>You must eat <strong>at least</strong> <strong>one</strong> candy per day until you have eaten all the candies.</li>
-</ul>
-
-<p>Construct a boolean array <code>answer</code> such that <code>answer.length == queries.length</code> and <code>answer[i]</code> is <code>true</code> if you can eat a candy of type <code>favoriteType<sub>i</sub></code> on day <code>favoriteDay<sub>i</sub></code> without eating <strong>more than</strong> <code>dailyCap<sub>i</sub></code> candies on <strong>any</strong> day, and <code>false</code> otherwise. Note that you can eat different types of candy on the same day, provided that you follow rule 2.</p>
-
-<p>Return <em>the constructed array </em><code>answer</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> candiesCount = [7,4,5,3,8], queries = [[0,2,2],[4,2,4],[2,13,1000000000]]
-<strong>Output:</strong> [true,false,true]
-<strong>Explanation:</strong>
-1- If you eat 2 candies (type 0) on day 0 and 2 candies (type 0) on day 1, you will eat a candy of type 0 on day 2.
-2- You can eat at most 4 candies each day.
-   If you eat 4 candies every day, you will eat 4 candies (type 0) on day 0 and 4 candies (type 0 and type 1) on day 1.
-   On day 2, you can only eat 4 candies (type 1 and type 2), so you cannot eat a candy of type 4 on day 2.
-3- If you eat 1 candy each day, you will eat a candy of type 2 on day 13.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> candiesCount = [5,2,6,4,1], queries = [[3,1,2],[4,10,3],[3,10,100],[4,100,30],[1,3,1]]
-<strong>Output:</strong> [false,true,true,false,false]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= candiesCount.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= candiesCount[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= queries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>queries[i].length == 3</code></li>
-	<li><code>0 &lt;= favoriteType<sub>i</sub> &lt; candiesCount.length</code></li>
-	<li><code>0 &lt;= favoriteDay<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= dailyCap<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The query is true if and only if your favorite day is in between the earliest and latest possible days to eat your favorite candy.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To get the earliest day, you need to eat dailyCap candies every day. To get the latest day, you need to eat 1 candy every day.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The latest possible day is the total number of candies with a smaller type plus the number of your favorite candy minus 1.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The earliest possible day that you can eat your favorite candy is the total number of candies with a smaller type divided by dailyCap.
-</details>
diff --git a/problems/candy-crush/README.md b/problems/candy-crush/README.md
deleted file mode 100644
index 1fe58d7ca..000000000
--- a/problems/candy-crush/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-comments "Remove Comments")
-　　　　　　　　　　　　　　　　
-[Next >](../find-pivot-index "Find Pivot Index")
-
-## [723. Candy Crush (Medium)](https://leetcode.com/problems/candy-crush "粉碎糖果")
-
-<p>This question is about implementing a basic elimination algorithm for Candy Crush.</p>
-
-<p>Given a 2D integer array <code>board</code> representing the grid of candy, different positive integers <code>board[i][j]</code> represent different types of candies. A value of <code>board[i][j] = 0</code> represents that the cell at position <code>(i, j)</code> is empty. The given board represents the state of the game following the player&#39;s move. Now, you need to restore the board to a <i>stable state</i> by crushing candies according to the following rules:</p>
-
-<ol>
-	<li>If three or more candies of the same type are adjacent vertically or horizontally, &quot;crush&quot; them all at the same time - these positions become empty.</li>
-	<li>After crushing all candies simultaneously, if an empty space on the board has candies on top of itself, then these candies will drop until they hit a candy or bottom at the same time. (No new candies will drop outside the top boundary.)</li>
-	<li>After the above steps, there may exist more candies that can be crushed. If so, you need to repeat the above steps.</li>
-	<li>If there does not exist more candies that can be crushed (ie. the board is <i>stable</i>), then return the current board.</li>
-</ol>
-
-<p>You need to perform the above rules until the board becomes stable, then return the current board.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Example:</b></p>
-
-<pre style="white-space: pre-line">
-<b>Input:</b>
-board = 
-[[110,5,112,113,114],[210,211,5,213,214],[310,311,3,313,314],[410,411,412,5,414],[5,1,512,3,3],[610,4,1,613,614],[710,1,2,713,714],[810,1,2,1,1],[1,1,2,2,2],[4,1,4,4,1014]]
-
-<b>Output:</b>
-[[0,0,0,0,0],[0,0,0,0,0],[0,0,0,0,0],[110,0,0,0,114],[210,0,0,0,214],[310,0,0,113,314],[410,0,0,213,414],[610,211,112,313,614],[710,311,412,613,714],[810,411,512,713,1014]]
-
-<b>Explanation:</b> 
-<img src="https://assets.leetcode.com/uploads/2018/10/12/candy_crush_example_2.png" style="width: 777px; height: 532px;" />
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>The length of <code>board</code> will be in the range [3, 50].</li>
-	<li>The length of <code>board[i]</code> will be in the range [3, 50].</li>
-	<li>Each <code>board[i][j]</code> will initially start as an integer in the range [1, 2000].</li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Carefully perform the "crush" and "gravity" steps.  In the crush step, flag each candy that should be removed, then go through and crush each flagged candy.  In the gravity step, collect the candy in each column and then rewrite the column appropriately.  Do these steps repeatedly until there's no work left to do.
-</details>
diff --git a/problems/candy-crush/candy_crush.go b/problems/candy-crush/candy_crush.go
deleted file mode 100644
index 4ff25967b..000000000
--- a/problems/candy-crush/candy_crush.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem723
diff --git a/problems/candy-crush/candy_crush_test.go b/problems/candy-crush/candy_crush_test.go
deleted file mode 100644
index 4ff25967b..000000000
--- a/problems/candy-crush/candy_crush_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem723
diff --git a/problems/candy/README.md b/problems/candy/README.md
deleted file mode 100644
index 870b0d873..000000000
--- a/problems/candy/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../gas-station "Gas Station")
-　　　　　　　　　　　　　　　　
-[Next >](../single-number "Single Number")
-
-## [135. Candy (Hard)](https://leetcode.com/problems/candy "分发糖果")
-
-<p>There are <code>n</code> children standing in a line. Each child is assigned a rating value given in the integer array <code>ratings</code>.</p>
-
-<p>You are giving candies to these children subjected to the following requirements:</p>
-
-<ul>
-	<li>Each child must have at least one candy.</li>
-	<li>Children with a higher rating get more candies than their neighbors.</li>
-</ul>
-
-<p>Return <em>the minimum number of candies you need to have to distribute the candies to the children</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> ratings = [1,0,2]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> You can allocate to the first, second and third child with 2, 1, 2 candies respectively.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> ratings = [1,2,2]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> You can allocate to the first, second and third child with 1, 2, 1 candies respectively.
-The third child gets 1 candy because it satisfies the above two conditions.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == ratings.length</code></li>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= ratings[i] &lt;= 2 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
diff --git a/problems/candy/candy.go b/problems/candy/candy.go
deleted file mode 100644
index 09c499563..000000000
--- a/problems/candy/candy.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem135
diff --git a/problems/candy/candy_test.go b/problems/candy/candy_test.go
deleted file mode 100644
index 09c499563..000000000
--- a/problems/candy/candy_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem135
diff --git a/problems/capacity-to-ship-packages-within-d-days/README.md b/problems/capacity-to-ship-packages-within-d-days/README.md
deleted file mode 100644
index 7bb5aba1c..000000000
--- a/problems/capacity-to-ship-packages-within-d-days/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pairs-of-songs-with-total-durations-divisible-by-60 "Pairs of Songs With Total Durations Divisible by 60")
-　　　　　　　　　　　　　　　　
-[Next >](../numbers-with-repeated-digits "Numbers With Repeated Digits")
-
-## [1011. Capacity To Ship Packages Within D Days (Medium)](https://leetcode.com/problems/capacity-to-ship-packages-within-d-days "在 D 天内送达包裹的能力")
-
-<p>A conveyor belt has packages that must be shipped from one port to another within <code>days</code> days.</p>
-
-<p>The <code>i<sup>th</sup></code> package on the conveyor belt has a weight of <code>weights[i]</code>. Each day, we load the ship with packages on the conveyor belt (in the order given by <code>weights</code>). We may not load more weight than the maximum weight capacity of the ship.</p>
-
-<p>Return the least weight capacity of the ship that will result in all the packages on the conveyor belt being shipped within <code>days</code> days.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> weights = [1,2,3,4,5,6,7,8,9,10], days = 5
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> A ship capacity of 15 is the minimum to ship all the packages in 5 days like this:
-1st day: 1, 2, 3, 4, 5
-2nd day: 6, 7
-3rd day: 8
-4th day: 9
-5th day: 10
-
-Note that the cargo must be shipped in the order given, so using a ship of capacity 14 and splitting the packages into parts like (2, 3, 4, 5), (1, 6, 7), (8), (9), (10) is not allowed.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> weights = [3,2,2,4,1,4], days = 3
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> A ship capacity of 6 is the minimum to ship all the packages in 3 days like this:
-1st day: 3, 2
-2nd day: 2, 4
-3rd day: 1, 4
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> weights = [1,2,3,1,1], days = 4
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-1st day: 1
-2nd day: 2
-3rd day: 3
-4th day: 1, 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= days &lt;= weights.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= weights[i] &lt;= 500</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Binary search on the answer.  We need a function possible(capacity) which returns true if and only if we can do the task in D days.
-</details>
diff --git a/problems/capacity-to-ship-packages-within-d-days/capacity_to_ship_packages_within_d_days.go b/problems/capacity-to-ship-packages-within-d-days/capacity_to_ship_packages_within_d_days.go
deleted file mode 100644
index 50fc17390..000000000
--- a/problems/capacity-to-ship-packages-within-d-days/capacity_to_ship_packages_within_d_days.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1011
-
-func shipWithinDays(weights []int, D int) int {
-	lo, hi := 0, 0
-	for _, w := range weights {
-		lo = max(lo, w)
-		hi += w
-	}
-
-	for lo < hi {
-		mid := (lo + hi) >> 1
-		days, cur := 1, 0
-		for _, w := range weights {
-			if cur+w > mid {
-				days++
-				cur = 0
-			}
-			cur += w
-		}
-		if days > D {
-			lo = mid + 1
-		} else {
-			hi = mid
-		}
-	}
-
-	return lo
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/capital-gainloss/README.md b/problems/capital-gainloss/README.md
deleted file mode 100644
index df3815de0..000000000
--- a/problems/capital-gainloss/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-happy-prefix "Longest Happy Prefix")
-　　　　　　　　　　　　　　　　
-[Next >](../find-lucky-integer-in-an-array "Find Lucky Integer in an Array")
-
-## [1393. Capital Gain/Loss (Medium)](https://leetcode.com/problems/capital-gainloss "股票的资本损益")
-
-<p>Table: <code>Stocks</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| stock_name    | varchar |
-| operation     | enum    |
-| operation_day | int     |
-| price         | int     |
-+---------------+---------+
-(stock_name, day) is the primary key for this table.
-The operation column is an ENUM of type ('Sell', 'Buy')
-Each row of this table indicates that the stock which has stock_name had an operation on the day operation_day with the price.
-It is guaranteed that each 'Sell' operation for a stock has a corresponding 'Buy' operation in a previous day.
-</pre>
- 
-Write an SQL query to report the Capital gain/loss for each stock.
-
-The capital gain/loss of a stock is total gain or loss after buying and selling the stock one or many times.
-
-Return the result table in any order.
-
-The query result format is in the following example:
-
-<pre>
-Stocks table:
-+---------------+-----------+---------------+--------+
-| stock_name    | operation | operation_day | price  |
-+---------------+-----------+---------------+--------+
-| Leetcode      | Buy       | 1             | 1000   |
-| Corona Masks  | Buy       | 2             | 10     |
-| Leetcode      | Sell      | 5             | 9000   |
-| Handbags      | Buy       | 17            | 30000  |
-| Corona Masks  | Sell      | 3             | 1010   |
-| Corona Masks  | Buy       | 4             | 1000   |
-| Corona Masks  | Sell      | 5             | 500    |
-| Corona Masks  | Buy       | 6             | 1000   |
-| Handbags      | Sell      | 29            | 7000   |
-| Corona Masks  | Sell      | 10            | 10000  |
-+---------------+-----------+---------------+--------+
-
-Result table:
-+---------------+-------------------+
-| stock_name    | capital_gain_loss |
-+---------------+-------------------+
-| Corona Masks  | 9500              |
-| Leetcode      | 8000              |
-| Handbags      | -23000            |
-+---------------+-------------------+
-Leetcode stock was bought at day 1 for 1000$ and was sold at day 5 for 9000$. Capital gain = 9000 - 1000 = 8000$.
-Handbags stock was bought at day 17 for 30000$ and was sold at day 29 for 7000$. Capital loss = 7000 - 30000 = -23000$.
-Corona Masks stock was bought at day 1 for 10$ and was sold at day 3 for 1010$. It was bought again at day 4 for 1000$ and was sold at day 5 for 500$. At last, it was bought at day 6 for 1000$ and was sold at day 10 for 10000$. Capital gain/loss is the sum of capital gains/losses for each ('Buy' --> 'Sell') operation = (1010 - 10) + (500 - 1000) + (10000 - 1000) = 1000 - 500 + 9000 = 9500$.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/capital-gainloss/mysql_schemas.sql b/problems/capital-gainloss/mysql_schemas.sql
deleted file mode 100644
index 8b782e9d7..000000000
--- a/problems/capital-gainloss/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create Table If Not Exists Stocks (stock_name varchar(15), operation ENUM('Sell', 'Buy'), operation_day int, price int);
-Truncate table Stocks;
-insert into Stocks (stock_name, operation, operation_day, price) values ('Leetcode', 'Buy', '1', '1000');
-insert into Stocks (stock_name, operation, operation_day, price) values ('Corona Masks', 'Buy', '2', '10');
-insert into Stocks (stock_name, operation, operation_day, price) values ('Leetcode', 'Sell', '5', '9000');
-insert into Stocks (stock_name, operation, operation_day, price) values ('Handbags', 'Buy', '17', '30000');
-insert into Stocks (stock_name, operation, operation_day, price) values ('Corona Masks', 'Sell', '3', '1010');
-insert into Stocks (stock_name, operation, operation_day, price) values ('Corona Masks', 'Buy', '4', '1000');
-insert into Stocks (stock_name, operation, operation_day, price) values ('Corona Masks', 'Sell', '5', '500');
-insert into Stocks (stock_name, operation, operation_day, price) values ('Corona Masks', 'Buy', '6', '1000');
-insert into Stocks (stock_name, operation, operation_day, price) values ('Handbags', 'Sell', '29', '7000');
-insert into Stocks (stock_name, operation, operation_day, price) values ('Corona Masks', 'Sell', '10', '10000');
diff --git a/problems/capitalize-the-title/README.md b/problems/capitalize-the-title/README.md
deleted file mode 100644
index 390a33635..000000000
--- a/problems/capitalize-the-title/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-all-ones-with-row-and-column-flips "Remove All Ones With Row and Column Flips")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-twin-sum-of-a-linked-list "Maximum Twin Sum of a Linked List")
-
-## [2129. Capitalize the Title (Easy)](https://leetcode.com/problems/capitalize-the-title "将标题首字母大写")
-
-<p>You are given a string <code>title</code> consisting of one or more words separated by a single space, where each word consists of English letters. <strong>Capitalize</strong> the string by changing the capitalization of each word such that:</p>
-
-<ul>
-	<li>If the length of the word is <code>1</code> or <code>2</code> letters, change all letters to lowercase.</li>
-	<li>Otherwise, change the first letter to uppercase and the remaining letters to lowercase.</li>
-</ul>
-
-<p>Return <em>the <strong>capitalized</strong> </em><code>title</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> title = &quot;capiTalIze tHe titLe&quot;
-<strong>Output:</strong> &quot;Capitalize The Title&quot;
-<strong>Explanation:</strong>
-Since all the words have a length of at least 3, the first letter of each word is uppercase, and the remaining letters are lowercase.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> title = &quot;First leTTeR of EACH Word&quot;
-<strong>Output:</strong> &quot;First Letter of Each Word&quot;
-<strong>Explanation:</strong>
-The word &quot;of&quot; has length 2, so it is all lowercase.
-The remaining words have a length of at least 3, so the first letter of each remaining word is uppercase, and the remaining letters are lowercase.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> title = &quot;i lOve leetcode&quot;
-<strong>Output:</strong> &quot;i Love Leetcode&quot;
-<strong>Explanation:</strong>
-The word &quot;i&quot; has length 1, so it is lowercase.
-The remaining words have a length of at least 3, so the first letter of each remaining word is uppercase, and the remaining letters are lowercase.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= title.length &lt;= 100</code></li>
-	<li><code>title</code> consists of words separated by a single space without any leading or trailing spaces.</li>
-	<li>Each word consists of uppercase and lowercase English letters and is <strong>non-empty</strong>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Firstly, try to find all the words present in the string.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-On the basis of each word's lengths, simulate the process explained in Problem.
-</details>
diff --git a/problems/car-fleet-ii/README.md b/problems/car-fleet-ii/README.md
deleted file mode 100644
index 49ff94884..000000000
--- a/problems/car-fleet-ii/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../equal-sum-arrays-with-minimum-number-of-operations "Equal Sum Arrays With Minimum Number of Operations")
-　　　　　　　　　　　　　　　　
-[Next >](../products-price-for-each-store "Product's Price for Each Store")
-
-## [1776. Car Fleet II (Hard)](https://leetcode.com/problems/car-fleet-ii "车队 II")
-
-<p>There are <code>n</code> cars traveling at different speeds in the same direction along a one-lane road. You are given an array <code>cars</code> of length <code>n</code>, where <code>cars[i] = [position<sub>i</sub>, speed<sub>i</sub>]</code> represents:</p>
-
-<ul>
-	<li><code>position<sub>i</sub></code> is the distance between the <code>i<sup>th</sup></code> car and the beginning of the road in meters. It is guaranteed that <code>position<sub>i</sub> &lt; position<sub>i+1</sub></code>.</li>
-	<li><code>speed<sub>i</sub></code> is the initial speed of the <code>i<sup>th</sup></code> car in meters per second.</li>
-</ul>
-
-<p>For simplicity, cars can be considered as points moving along the number line. Two cars collide when they occupy the same position. Once a car collides with another car, they unite and form a single car fleet. The cars in the formed fleet will have the same position and the same speed, which is the initial speed of the <strong>slowest</strong> car in the fleet.</p>
-
-<p>Return an array <code>answer</code>, where <code>answer[i]</code> is the time, in seconds, at which the <code>i<sup>th</sup></code> car collides with the next car, or <code>-1</code> if the car does not collide with the next car. Answers within <code>10<sup>-5</sup></code> of the actual answers are accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> cars = [[1,2],[2,1],[4,3],[7,2]]
-<strong>Output:</strong> [1.00000,-1.00000,3.00000,-1.00000]
-<strong>Explanation:</strong> After exactly one second, the first car will collide with the second car, and form a car fleet with speed 1 m/s. After exactly 3 seconds, the third car will collide with the fourth car, and form a car fleet with speed 2 m/s.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> cars = [[3,4],[5,4],[6,3],[9,1]]
-<strong>Output:</strong> [2.00000,1.00000,1.50000,-1.00000]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= cars.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= position<sub>i</sub>, speed<sub>i</sub> &lt;= 10<sup>6</sup></code></li>
-	<li><code>position<sub>i</sub> &lt; position<sub>i+1</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Car Fleet](../car-fleet) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can simply ignore the merging of any car fleet, simply assume they cross each other. Now the aim is to find the first car to the right, which intersects with the current car before any other.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Assume we have already considered all cars to the right already, now the current car is to be considered. Let’s ignore all cars with speeds higher than the current car since the current car cannot intersect with those ones. Now, all cars to the right having speed strictly less than current car are to be considered. Now, for two cars c1 and c2 with positions p1 and p2 (p1 < p2) and speed s1 and s2 (s1 > s2), if c1 and c2 intersect before the current car and c2, then c1 can never be the first car of intersection for any car to the left of current car including current car. So we can remove that car from our consideration.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We can see that we can maintain candidate cars in this way using a stack, removing cars with speed greater than or equal to current car, and then removing cars which can never be first point of intersection. The first car after this process (if any) would be first point of intersection.
-</details>
diff --git a/problems/car-fleet/README.md b/problems/car-fleet/README.md
deleted file mode 100644
index 3c65d371a..000000000
--- a/problems/car-fleet/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../peak-index-in-a-mountain-array "Peak Index in a Mountain Array")
-　　　　　　　　　　　　　　　　
-[Next >](../k-similar-strings "K-Similar Strings")
-
-## [853. Car Fleet (Medium)](https://leetcode.com/problems/car-fleet "车队")
-
-<p>There are <code>n</code> cars going to the same destination along a one-lane road. The destination is <code>target</code> miles away.</p>
-
-<p>You are given two integer array <code>position</code> and <code>speed</code>, both of length <code>n</code>, where <code>position[i]</code> is the position of the <code>i<sup>th</sup></code> car and <code>speed[i]</code> is the speed of the <code>i<sup>th</sup></code> car (in miles per hour).</p>
-
-<p>A car can never pass another car ahead of it, but it can catch up to it, and drive bumper to bumper <strong>at the same speed</strong>.</p>
-
-<p>The distance between these two cars is ignored (i.e., they are assumed to have the same position).</p>
-
-<p>A car fleet is some non-empty set of cars driving at the same position and same speed. Note that a single car is also a car fleet.</p>
-
-<p>If a car catches up to a car fleet right at the destination point, it will still be considered as one car fleet.</p>
-
-<p>Return <em>the number of car fleets that will arrive at the destination</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 12, position = [10,8,0,5,3], speed = [2,4,1,1,3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-The cars starting at 10 and 8 become a fleet, meeting each other at 12.
-The car starting at 0 doesn&#39;t catch up to any other car, so it is a fleet by itself.
-The cars starting at 5 and 3 become a fleet, meeting each other at 6.
-Note that no other cars meet these fleets before the destination, so the answer is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 10, position = [3], speed = [3]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == position.length == speed.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt; target &lt;= 10<sup>6</sup></code></li>
-	<li><code>0 &lt;= position[i] &lt; target</code></li>
-	<li>All the values of <code>position</code> are <strong>unique</strong>.</li>
-	<li><code>0 &lt; speed[i] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/car-fleet/car_fleet.go b/problems/car-fleet/car_fleet.go
deleted file mode 100644
index 99153dc9a..000000000
--- a/problems/car-fleet/car_fleet.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem853
diff --git a/problems/car-fleet/car_fleet_test.go b/problems/car-fleet/car_fleet_test.go
deleted file mode 100644
index 99153dc9a..000000000
--- a/problems/car-fleet/car_fleet_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem853
diff --git a/problems/car-pooling/README.md b/problems/car-pooling/README.md
deleted file mode 100644
index ee4665fef..000000000
--- a/problems/car-pooling/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../statistics-from-a-large-sample "Statistics from a Large Sample")
-　　　　　　　　　　　　　　　　
-[Next >](../find-in-mountain-array "Find in Mountain Array")
-
-## [1094. Car Pooling (Medium)](https://leetcode.com/problems/car-pooling "拼车")
-
-<p>There is a car with <code>capacity</code> empty seats. The vehicle only drives east (i.e., it cannot turn around and drive west).</p>
-
-<p>You are given the integer <code>capacity</code> and an array <code>trips</code> where <code>trips[i] = [numPassengers<sub>i</sub>, from<sub>i</sub>, to<sub>i</sub>]</code> indicates that the <code>i<sup>th</sup></code> trip has <code>numPassengers<sub>i</sub></code> passengers and the locations to pick them up and drop them off are <code>from<sub>i</sub></code> and <code>to<sub>i</sub></code> respectively. The locations are given as the number of kilometers due east from the car&#39;s initial location.</p>
-
-<p>Return <code>true</code><em> if it is possible to pick up and drop off all passengers for all the given trips, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> trips = [[2,1,5],[3,3,7]], capacity = 4
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> trips = [[2,1,5],[3,3,7]], capacity = 5
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= trips.length &lt;= 1000</code></li>
-	<li><code>trips[i].length == 3</code></li>
-	<li><code>1 &lt;= numPassengers<sub>i</sub> &lt;= 100</code></li>
-	<li><code>0 &lt;= from<sub>i</sub> &lt; to<sub>i</sub> &lt;= 1000</code></li>
-	<li><code>1 &lt;= capacity &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Meeting Rooms II](../meeting-rooms-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the pickup and dropoff events by location, then process them in order.
-</details>
diff --git a/problems/car-pooling/car_pooling.go b/problems/car-pooling/car_pooling.go
deleted file mode 100644
index c5254f4c5..000000000
--- a/problems/car-pooling/car_pooling.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem1094
-
-func carPooling(trips [][]int, capacity int) bool {
-	location := [1001]int{}
-	for _, t := range trips {
-		num, start, end := t[0], t[1], t[2]
-		location[start] += num
-		location[end] -= num
-	}
-
-	p := 0
-	for _, c := range location {
-		p += c
-		if p > capacity {
-			return false
-		}
-	}
-	return true
-}
diff --git a/problems/card-flipping-game/README.md b/problems/card-flipping-game/README.md
deleted file mode 100644
index 90ae2335a..000000000
--- a/problems/card-flipping-game/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-distance-to-a-character "Shortest Distance to a Character")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-trees-with-factors "Binary Trees With Factors")
-
-## [822. Card Flipping Game (Medium)](https://leetcode.com/problems/card-flipping-game "翻转卡片游戏")
-
-<p>You are given <code>n</code> cards, with a positive integer printed on the front and back of each card (possibly different). You can flip any number of cards (possibly zero).</p>
-
-<p>After choosing the front and the back of each card, you will pick each card, and if the integer printed on the back of this card is not printed on the front of any other card, then this integer is <strong>good</strong>.</p>
-
-<p>You are given two integer array <code>fronts</code> and <code>backs</code> where <code>fronts[i]</code> and <code>backs[i]</code> are the integers printer on the front and the back of the <code>i<sup>th</sup></code> card respectively.</p>
-
-<p>Return <em>the smallest good and integer after flipping the cards</em>. If there are no good integers, return <code>0</code>.</p>
-
-<p><strong>Note</strong> that a <strong>flip</strong> swaps the front and back numbers, so the value on the front is now on the back and vice versa.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> fronts = [1,2,4,4,7], backs = [1,3,4,1,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> If we flip the second card, the fronts are [1,3,4,4,7] and the backs are [1,2,4,1,3].
-We choose the second card, which has the number 2 on the back, and it is not on the front of any card, so 2 is good.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> fronts = [1], backs = [1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == fronts.length</code></li>
-	<li><code>n == backs.length</code></li>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= fronts[i], backs[i] &lt;= 2000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
diff --git a/problems/card-flipping-game/card_flipping_game.go b/problems/card-flipping-game/card_flipping_game.go
deleted file mode 100644
index 342b1a8bd..000000000
--- a/problems/card-flipping-game/card_flipping_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem822
diff --git a/problems/card-flipping-game/card_flipping_game_test.go b/problems/card-flipping-game/card_flipping_game_test.go
deleted file mode 100644
index 342b1a8bd..000000000
--- a/problems/card-flipping-game/card_flipping_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem822
diff --git a/problems/cat-and-mouse-ii/README.md b/problems/cat-and-mouse-ii/README.md
deleted file mode 100644
index 87c97a15a..000000000
--- a/problems/cat-and-mouse-ii/README.md
+++ /dev/null
@@ -1,98 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-submatrix-with-rearrangements "Largest Submatrix With Rearrangements")
-　　　　　　　　　　　　　　　　
-[Next >](../find-followers-count "Find Followers Count")
-
-## [1728. Cat and Mouse II (Hard)](https://leetcode.com/problems/cat-and-mouse-ii "猫和老鼠 II")
-
-<p>A game is played by a cat and a mouse named Cat and Mouse.</p>
-
-<p>The environment is represented by a <code>grid</code> of size <code>rows x cols</code>, where each element is a wall, floor, player (Cat, Mouse), or food.</p>
-
-<ul>
-	<li>Players are represented by the characters <code>&#39;C&#39;</code>(Cat)<code>,&#39;M&#39;</code>(Mouse).</li>
-	<li>Floors are represented by the character <code>&#39;.&#39;</code> and can be walked on.</li>
-	<li>Walls are represented by the character <code>&#39;#&#39;</code> and cannot be walked on.</li>
-	<li>Food is represented by the character <code>&#39;F&#39;</code> and can be walked on.</li>
-	<li>There is only one of each character <code>&#39;C&#39;</code>, <code>&#39;M&#39;</code>, and <code>&#39;F&#39;</code> in <code>grid</code>.</li>
-</ul>
-
-<p>Mouse and Cat play according to the following rules:</p>
-
-<ul>
-	<li>Mouse <strong>moves first</strong>, then they take turns to move.</li>
-	<li>During each turn, Cat and Mouse can jump in one of the four directions (left, right, up, down). They cannot jump over the wall nor outside of the <code>grid</code>.</li>
-	<li><code>catJump, mouseJump</code> are the maximum lengths Cat and Mouse can jump at a time, respectively. Cat and Mouse can jump less than the maximum length.</li>
-	<li>Staying in the same position is allowed.</li>
-	<li>Mouse can jump over Cat.</li>
-</ul>
-
-<p>The game can end in 4 ways:</p>
-
-<ul>
-	<li>If Cat occupies the same position as Mouse, Cat wins.</li>
-	<li>If Cat reaches the food first, Cat wins.</li>
-	<li>If Mouse reaches the food first, Mouse wins.</li>
-	<li>If Mouse cannot get to the food within 1000 turns, Cat wins.</li>
-</ul>
-
-<p>Given a <code>rows x cols</code> matrix <code>grid</code> and two integers <code>catJump</code> and <code>mouseJump</code>, return <code>true</code><em> if Mouse can win the game if both Cat and Mouse play optimally, otherwise return </em><code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/12/sample_111_1955.png" style="width: 580px; height: 239px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot;####F&quot;,&quot;#C...&quot;,&quot;M....&quot;], catJump = 1, mouseJump = 2
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Cat cannot catch Mouse on its turn nor can it get the food before Mouse.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/12/sample_2_1955.png" style="width: 580px; height: 175px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot;M.C...F&quot;], catJump = 1, mouseJump = 4
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [&quot;M.C...F&quot;], catJump = 1, mouseJump = 3
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>rows == grid.length</code></li>
-	<li><code>cols = grid[i].length</code></li>
-	<li><code>1 &lt;= rows, cols &lt;= 8</code></li>
-	<li><code>grid[i][j]</code> consist only of characters <code>&#39;C&#39;</code>, <code>&#39;M&#39;</code>, <code>&#39;F&#39;</code>, <code>&#39;.&#39;</code>, and <code>&#39;#&#39;</code>.</li>
-	<li>There is only one of each character <code>&#39;C&#39;</code>, <code>&#39;M&#39;</code>, and <code>&#39;F&#39;</code> in <code>grid</code>.</li>
-	<li><code>1 &lt;= catJump, mouseJump &lt;= 8</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Similar Questions
-  1. [Escape The Ghosts](../escape-the-ghosts) (Medium)
-  1. [Cat and Mouse](../cat-and-mouse) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try working backward: consider all trivial states you know to be winning or losing, and work backward to determine which other states can be labeled as winning or losing.
-</details>
diff --git a/problems/cat-and-mouse/README.md b/problems/cat-and-mouse/README.md
deleted file mode 100644
index 20304f04b..000000000
--- a/problems/cat-and-mouse/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-an-array "Sort an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../x-of-a-kind-in-a-deck-of-cards "X of a Kind in a Deck of Cards")
-
-## [913. Cat and Mouse (Hard)](https://leetcode.com/problems/cat-and-mouse "猫和老鼠")
-
-<p>A game on an <strong>undirected</strong> graph is played by two players, Mouse and Cat, who alternate turns.</p>
-
-<p>The graph is given as follows: <code>graph[a]</code> is a list of all nodes <code>b</code> such that <code>ab</code> is an edge of the graph.</p>
-
-<p>The mouse starts at node <code>1</code> and goes first, the cat starts at node <code>2</code> and goes second, and there is a hole at node <code>0</code>.</p>
-
-<p>During each player&#39;s turn, they <strong>must</strong> travel along one&nbsp;edge of the graph that meets where they are.&nbsp; For example, if the Mouse is at node 1, it <strong>must</strong> travel to any node in <code>graph[1]</code>.</p>
-
-<p>Additionally, it is not allowed for the Cat to travel to the Hole (node 0.)</p>
-
-<p>Then, the game can end in three&nbsp;ways:</p>
-
-<ul>
-	<li>If ever the Cat occupies the same node as the Mouse, the Cat wins.</li>
-	<li>If ever the Mouse reaches the Hole, the Mouse wins.</li>
-	<li>If ever a position is repeated (i.e., the players are in the same position as a previous turn, and&nbsp;it is the same player&#39;s turn to move), the game is a draw.</li>
-</ul>
-
-<p>Given a <code>graph</code>, and assuming both players play optimally, return</p>
-
-<ul>
-	<li><code>1</code>&nbsp;if the mouse wins the game,</li>
-	<li><code>2</code>&nbsp;if the cat wins the game, or</li>
-	<li><code>0</code>&nbsp;if the game is a draw.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/17/cat1.jpg" style="width: 300px; height: 300px;" />
-<pre>
-<strong>Input:</strong> graph = [[2,5],[3],[0,4,5],[1,4,5],[2,3],[0,2,3]]
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/17/cat2.jpg" style="width: 200px; height: 200px;" />
-<pre>
-<strong>Input:</strong> graph = [[1,3],[0],[3],[0,2]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= graph.length &lt;= 50</code></li>
-	<li><code>1&nbsp;&lt;= graph[i].length &lt; graph.length</code></li>
-	<li><code>0 &lt;= graph[i][j] &lt; graph.length</code></li>
-	<li><code>graph[i][j] != i</code></li>
-	<li><code>graph[i]</code> is unique.</li>
-	<li>The mouse and the cat can always move.&nbsp;</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
diff --git a/problems/cat-and-mouse/cat_and_mouse.go b/problems/cat-and-mouse/cat_and_mouse.go
deleted file mode 100644
index ca305e1f7..000000000
--- a/problems/cat-and-mouse/cat_and_mouse.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem913
diff --git a/problems/cat-and-mouse/cat_and_mouse_test.go b/problems/cat-and-mouse/cat_and_mouse_test.go
deleted file mode 100644
index ca305e1f7..000000000
--- a/problems/cat-and-mouse/cat_and_mouse_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem913
diff --git a/problems/cells-with-odd-values-in-a-matrix/README.md b/problems/cells-with-odd-values-in-a-matrix/README.md
deleted file mode 100644
index b8fc0de26..000000000
--- a/problems/cells-with-odd-values-in-a-matrix/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../average-selling-price "Average Selling Price")
-　　　　　　　　　　　　　　　　
-[Next >](../reconstruct-a-2-row-binary-matrix "Reconstruct a 2-Row Binary Matrix")
-
-## [1252. Cells with Odd Values in a Matrix (Easy)](https://leetcode.com/problems/cells-with-odd-values-in-a-matrix "奇数值单元格的数目")
-
-<p>There is an <code>m x n</code> matrix that is initialized to all <code>0</code>&#39;s. There is also a 2D array <code>indices</code> where each <code>indices[i] = [r<sub>i</sub>, c<sub>i</sub>]</code> represents a <strong>0-indexed location</strong> to perform some increment operations on the matrix.</p>
-
-<p>For each location <code>indices[i]</code>, do <strong>both</strong> of the following:</p>
-
-<ol>
-	<li>Increment <strong>all</strong> the cells on row <code>r<sub>i</sub></code>.</li>
-	<li>Increment <strong>all</strong> the cells on column <code>c<sub>i</sub></code>.</li>
-</ol>
-
-<p>Given <code>m</code>, <code>n</code>, and <code>indices</code>, return <em>the <strong>number of odd-valued cells</strong> in the matrix after applying the increment to all locations in </em><code>indices</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/10/30/e1.png" style="width: 600px; height: 118px;" />
-<pre>
-<strong>Input:</strong> m = 2, n = 3, indices = [[0,1],[1,1]]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Initial matrix = [[0,0,0],[0,0,0]].
-After applying first increment it becomes [[1,2,1],[0,1,0]].
-The final matrix is [[1,3,1],[1,3,1]], which contains 6 odd numbers.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/10/30/e2.png" style="width: 600px; height: 150px;" />
-<pre>
-<strong>Input:</strong> m = 2, n = 2, indices = [[1,1],[0,0]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Final matrix = [[2,2],[2,2]]. There are no odd numbers in the final matrix.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>1 &lt;= indices.length &lt;= 100</code></li>
-	<li><code>0 &lt;= r<sub>i</sub> &lt; m</code></li>
-	<li><code>0 &lt;= c<sub>i</sub> &lt; n</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you solve this in <code>O(n + m + indices.length)</code> time with only <code>O(n + m)</code> extra space?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulation : With small constraints, it is possible to apply changes to each row and column and count odd cells after applying it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can accumulate the number you should add to each row and column and then you can count the number of odd cells.
-</details>
diff --git a/problems/chalkboard-xor-game/README.md b/problems/chalkboard-xor-game/README.md
deleted file mode 100644
index b3e8c6744..000000000
--- a/problems/chalkboard-xor-game/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../expressive-words "Expressive Words")
-　　　　　　　　　　　　　　　　
-[Next >](../subdomain-visit-count "Subdomain Visit Count")
-
-## [810. Chalkboard XOR Game (Hard)](https://leetcode.com/problems/chalkboard-xor-game "黑板异或游戏")
-
-<p>You are given an array of integers <code>nums</code> represents the numbers written on a chalkboard.</p>
-
-<p>Alice and Bob take turns erasing exactly one number from the chalkboard, with Alice starting first. If erasing a number causes the bitwise XOR of all the elements of the chalkboard to become <code>0</code>, then that player loses. The bitwise XOR of one element is that element itself, and the bitwise XOR of no elements is <code>0</code>.</p>
-
-<p>Also, if any player starts their turn with the bitwise XOR of all the elements of the chalkboard equal to <code>0</code>, then that player wins.</p>
-
-<p>Return <code>true</code> <em>if and only if Alice wins the game, assuming both players play optimally</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> 
-Alice has two choices: erase 1 or erase 2. 
-If she erases 1, the nums array becomes [1, 2]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 2 = 3. Now Bob can remove any element he wants, because Alice will be the one to erase the last element and she will lose. 
-If Alice erases 2 first, now nums become [1, 1]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 1 = 0. Alice will lose.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt; 2<sup>16</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Brainteaser](../../tag/brainteaser/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
diff --git a/problems/chalkboard-xor-game/chalkboard_xor_game.go b/problems/chalkboard-xor-game/chalkboard_xor_game.go
deleted file mode 100644
index 693b94d4b..000000000
--- a/problems/chalkboard-xor-game/chalkboard_xor_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem810
diff --git a/problems/chalkboard-xor-game/chalkboard_xor_game_test.go b/problems/chalkboard-xor-game/chalkboard_xor_game_test.go
deleted file mode 100644
index 693b94d4b..000000000
--- a/problems/chalkboard-xor-game/chalkboard_xor_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem810
diff --git a/problems/champagne-tower/README.md b/problems/champagne-tower/README.md
deleted file mode 100644
index 198366efc..000000000
--- a/problems/champagne-tower/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-rotation-with-highest-score "Smallest Rotation with Highest Score")
-　　　　　　　　　　　　　　　　
-[Next >](../similar-rgb-color "Similar RGB Color")
-
-## [799. Champagne Tower (Medium)](https://leetcode.com/problems/champagne-tower "香槟塔")
-
-<p>We stack glasses in a pyramid, where the <strong>first</strong> row has <code>1</code> glass, the <strong>second</strong> row has <code>2</code> glasses, and so on until the 100<sup>th</sup> row.&nbsp; Each glass holds one cup&nbsp;of champagne.</p>
-
-<p>Then, some champagne is poured into the first glass at the top.&nbsp; When the topmost glass is full, any excess liquid poured will fall equally to the glass immediately to the left and right of it.&nbsp; When those glasses become full, any excess champagne will fall equally to the left and right of those glasses, and so on.&nbsp; (A glass at the bottom row has its excess champagne fall on the floor.)</p>
-
-<p>For example, after one cup of champagne is poured, the top most glass is full.&nbsp; After two cups of champagne are poured, the two glasses on the second row are half full.&nbsp; After three cups of champagne are poured, those two cups become full - there are 3 full glasses total now.&nbsp; After four cups of champagne are poured, the third row has the middle glass half full, and the two outside glasses are a quarter full, as pictured below.</p>
-
-<p><img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/03/09/tower.png" style="height: 241px; width: 350px;" /></p>
-
-<p>Now after pouring some non-negative integer cups of champagne, return how full the <code>j<sup>th</sup></code> glass in the <code>i<sup>th</sup></code> row is (both <code>i</code> and <code>j</code> are 0-indexed.)</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> poured = 1, query_row = 1, query_glass = 1
-<strong>Output:</strong> 0.00000
-<strong>Explanation:</strong> We poured 1 cup of champange to the top glass of the tower (which is indexed as (0, 0)). There will be no excess liquid so all the glasses under the top glass will remain empty.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> poured = 2, query_row = 1, query_glass = 1
-<strong>Output:</strong> 0.50000
-<strong>Explanation:</strong> We poured 2 cups of champange to the top glass of the tower (which is indexed as (0, 0)). There is one cup of excess liquid. The glass indexed as (1, 0) and the glass indexed as (1, 1) will share the excess liquid equally, and each will get half cup of champange.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> poured = 100000009, query_row = 33, query_glass = 17
-<strong>Output:</strong> 1.00000
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;=&nbsp;poured &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= query_glass &lt;= query_row&nbsp;&lt; 100</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/champagne-tower/champagne_tower.go b/problems/champagne-tower/champagne_tower.go
deleted file mode 100644
index a54d9ee72..000000000
--- a/problems/champagne-tower/champagne_tower.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem799
diff --git a/problems/champagne-tower/champagne_tower_test.go b/problems/champagne-tower/champagne_tower_test.go
deleted file mode 100644
index a54d9ee72..000000000
--- a/problems/champagne-tower/champagne_tower_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem799
diff --git a/problems/change-minimum-characters-to-satisfy-one-of-three-conditions/README.md b/problems/change-minimum-characters-to-satisfy-one-of-three-conditions/README.md
deleted file mode 100644
index 98008661a..000000000
--- a/problems/change-minimum-characters-to-satisfy-one-of-three-conditions/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../latest-time-by-replacing-hidden-digits "Latest Time by Replacing Hidden Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../find-kth-largest-xor-coordinate-value "Find Kth Largest XOR Coordinate Value")
-
-## [1737. Change Minimum Characters to Satisfy One of Three Conditions (Medium)](https://leetcode.com/problems/change-minimum-characters-to-satisfy-one-of-three-conditions "满足三条件之一需改变的最少字符数")
-
-<p>You are given two strings <code>a</code> and <code>b</code> that consist of lowercase letters. In one operation, you can change any character in <code>a</code> or <code>b</code> to <strong>any lowercase letter</strong>.</p>
-
-<p>Your goal is to satisfy <strong>one</strong> of the following three conditions:</p>
-
-<ul>
-	<li><strong>Every</strong> letter in <code>a</code> is <strong>strictly less</strong> than <strong>every</strong> letter in <code>b</code> in the alphabet.</li>
-	<li><strong>Every</strong> letter in <code>b</code> is <strong>strictly less</strong> than <strong>every</strong> letter in <code>a</code> in the alphabet.</li>
-	<li><strong>Both</strong> <code>a</code> and <code>b</code> consist of <strong>only one</strong> distinct letter.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum</strong> number of operations needed to achieve your goal.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;aba&quot;, b = &quot;caa&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Consider the best way to make each condition true:
-1) Change b to &quot;ccc&quot; in 2 operations, then every letter in a is less than every letter in b.
-2) Change a to &quot;bbb&quot; and b to &quot;aaa&quot; in 3 operations, then every letter in b is less than every letter in a.
-3) Change a to &quot;aaa&quot; and b to &quot;aaa&quot; in 2 operations, then a and b consist of one distinct letter.
-The best way was done in 2 operations (either condition 1 or condition 3).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;dabadd&quot;, b = &quot;cda&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The best way is to make condition 1 true by changing b to &quot;eee&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= a.length, b.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>a</code> and <code>b</code> consist only of lowercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate on each letter in the alphabet, and check the smallest number of operations needed to make it one of the following: the largest letter in a and smaller than the smallest one in b, vice versa, or let a and b consist only of this letter.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For the first 2 conditions, take care that you can only change characters to lowercase letters, so you can't make 'z' the smallest letter in one of the strings or 'a' the largest letter in one of them.
-</details>
diff --git a/problems/change-the-root-of-a-binary-tree/README.md b/problems/change-the-root-of-a-binary-tree/README.md
deleted file mode 100644
index 532482af4..000000000
--- a/problems/change-the-root-of-a-binary-tree/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-initial-energy-to-finish-tasks "Minimum Initial Energy to Finish Tasks")
-　　　　　　　　　　　　　　　　
-[Next >](../fix-names-in-a-table "Fix Names in a Table")
-
-## [1666. Change the Root of a Binary Tree (Medium)](https://leetcode.com/problems/change-the-root-of-a-binary-tree "改变二叉树的根节点")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Start traversing from the leaf. Always go up till you reach the root.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Change pointers as asked, make the current node's parent its left child, and make the left child the right one if needed.
-</details>
diff --git a/problems/cheapest-flights-within-k-stops/README.md b/problems/cheapest-flights-within-k-stops/README.md
deleted file mode 100644
index 04469ee9c..000000000
--- a/problems/cheapest-flights-within-k-stops/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-th-smallest-prime-fraction "K-th Smallest Prime Fraction")
-　　　　　　　　　　　　　　　　
-[Next >](../rotated-digits "Rotated Digits")
-
-## [787. Cheapest Flights Within K Stops (Medium)](https://leetcode.com/problems/cheapest-flights-within-k-stops "K 站中转内最便宜的航班")
-
-<p>There are <code>n</code> cities connected by some number of flights. You are given an array <code>flights</code> where <code>flights[i] = [from<sub>i</sub>, to<sub>i</sub>, price<sub>i</sub>]</code> indicates that there is a flight from city <code>from<sub>i</sub></code> to city <code>to<sub>i</sub></code> with cost <code>price<sub>i</sub></code>.</p>
-
-<p>You are also given three integers <code>src</code>, <code>dst</code>, and <code>k</code>, return <em><strong>the cheapest price</strong> from </em><code>src</code><em> to </em><code>dst</code><em> with at most </em><code>k</code><em> stops. </em>If there is no such route, return<em> </em><code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/02/16/995.png" style="height: 360px; width: 492px;" />
-<pre>
-<strong>Input:</strong> n = 3, flights = [[0,1,100],[1,2,100],[0,2,500]], src = 0, dst = 2, k = 1
-<strong>Output:</strong> 200
-<strong>Explanation:</strong> The graph is shown.
-The cheapest price from city <code>0</code> to city <code>2</code> with at most 1 stop costs 200, as marked red in the picture.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/02/16/995.png" style="height: 360px; width: 492px;" />
-<pre>
-<strong>Input:</strong> n = 3, flights = [[0,1,100],[1,2,100],[0,2,500]], src = 0, dst = 2, k = 0
-<strong>Output:</strong> 500
-<strong>Explanation:</strong> The graph is shown.
-The cheapest price from city <code>0</code> to city <code>2</code> with at most 0 stop costs 500, as marked blue in the picture.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>0 &lt;= flights.length &lt;= (n * (n - 1) / 2)</code></li>
-	<li><code>flights[i].length == 3</code></li>
-	<li><code>0 &lt;= from<sub>i</sub>, to<sub>i</sub> &lt; n</code></li>
-	<li><code>from<sub>i</sub> != to<sub>i</sub></code></li>
-	<li><code>1 &lt;= price<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li>There will not be any multiple flights between two cities.</li>
-	<li><code>0 &lt;= src, dst, k &lt; n</code></li>
-	<li><code>src != dst</code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Maximum Vacation Days](../maximum-vacation-days) (Hard)
diff --git a/problems/cheapest-flights-within-k-stops/cheapest_flights_within_k_stops.go b/problems/cheapest-flights-within-k-stops/cheapest_flights_within_k_stops.go
deleted file mode 100644
index 32b32c056..000000000
--- a/problems/cheapest-flights-within-k-stops/cheapest_flights_within_k_stops.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem787
diff --git a/problems/cheapest-flights-within-k-stops/cheapest_flights_within_k_stops_test.go b/problems/cheapest-flights-within-k-stops/cheapest_flights_within_k_stops_test.go
deleted file mode 100644
index 32b32c056..000000000
--- a/problems/cheapest-flights-within-k-stops/cheapest_flights_within_k_stops_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem787
diff --git a/problems/check-array-formation-through-concatenation/README.md b/problems/check-array-formation-through-concatenation/README.md
deleted file mode 100644
index 21e3f6946..000000000
--- a/problems/check-array-formation-through-concatenation/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-form-a-target-string-given-a-dictionary "Number of Ways to Form a Target String Given a Dictionary")
-　　　　　　　　　　　　　　　　
-[Next >](../count-sorted-vowel-strings "Count Sorted Vowel Strings")
-
-## [1640. Check Array Formation Through Concatenation (Easy)](https://leetcode.com/problems/check-array-formation-through-concatenation "能否连接形成数组")
-
-<p>You are given an array of <strong>distinct</strong> integers <code>arr</code> and an array of integer arrays <code>pieces</code>, where the integers in <code>pieces</code> are <strong>distinct</strong>. Your goal is to form <code>arr</code> by concatenating the arrays in <code>pieces</code> <strong>in any order</strong>. However, you are <strong>not</strong> allowed to reorder the integers in each array <code>pieces[i]</code>.</p>
-
-<p>Return <code>true</code> <em>if it is possible </em><em>to form the array </em><code>arr</code><em> from </em><code>pieces</code>. Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [15,88], pieces = [[88],[15]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Concatenate [15] then [88]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [49,18,16], pieces = [[16,18,49]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Even though the numbers match, we cannot reorder pieces[0].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [91,4,64,78], pieces = [[78],[4,64],[91]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Concatenate [91] then [4,64] then [78]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= pieces.length &lt;= arr.length &lt;= 100</code></li>
-	<li><code>sum(pieces[i].length) == arr.length</code></li>
-	<li><code>1 &lt;= pieces[i].length &lt;= arr.length</code></li>
-	<li><code>1 &lt;= arr[i], pieces[i][j] &lt;= 100</code></li>
-	<li>The integers in <code>arr</code> are <strong>distinct</strong>.</li>
-	<li>The integers in <code>pieces</code> are <strong>distinct</strong> (i.e., If we flatten pieces in a 1D array, all the integers in this array are distinct).</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that the distinct part means that every position in the array belongs to only one piece
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Note that you can get the piece every position belongs to naively
-</details>
diff --git a/problems/check-completeness-of-a-binary-tree/README.md b/problems/check-completeness-of-a-binary-tree/README.md
deleted file mode 100644
index e6538cb8f..000000000
--- a/problems/check-completeness-of-a-binary-tree/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../prison-cells-after-n-days "Prison Cells After N Days")
-　　　　　　　　　　　　　　　　
-[Next >](../regions-cut-by-slashes "Regions Cut By Slashes")
-
-## [958. Check Completeness of a Binary Tree (Medium)](https://leetcode.com/problems/check-completeness-of-a-binary-tree "二叉树的完全性检验")
-
-<p>Given the <code>root</code> of a binary tree, determine if it is a <em>complete binary tree</em>.</p>
-
-<p>In a <strong><a href="http://en.wikipedia.org/wiki/Binary_tree#Types_of_binary_trees" target="_blank">complete binary tree</a></strong>, every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between <code>1</code> and <code>2<sup>h</sup></code> nodes inclusive at the last level <code>h</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/complete-binary-tree-1.png" style="width: 180px; height: 145px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,6]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Every level before the last is full (ie. levels with node-values {1} and {2, 3}), and all nodes in the last level ({4, 5, 6}) are as far left as possible.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/complete-binary-tree-2.png" style="width: 200px; height: 145px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,null,7]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The node with value 7 isn&#39;t as far left as possible.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 100]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/check-completeness-of-a-binary-tree/check_completeness_of_a_binary_tree.go b/problems/check-completeness-of-a-binary-tree/check_completeness_of_a_binary_tree.go
deleted file mode 100644
index 8bf9a0eea..000000000
--- a/problems/check-completeness-of-a-binary-tree/check_completeness_of_a_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem958
diff --git a/problems/check-completeness-of-a-binary-tree/check_completeness_of_a_binary_tree_test.go b/problems/check-completeness-of-a-binary-tree/check_completeness_of_a_binary_tree_test.go
deleted file mode 100644
index 8bf9a0eea..000000000
--- a/problems/check-completeness-of-a-binary-tree/check_completeness_of_a_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem958
diff --git a/problems/check-if-a-number-is-majority-element-in-a-sorted-array/README.md b/problems/check-if-a-number-is-majority-element-in-a-sorted-array/README.md
deleted file mode 100644
index ca9cb277e..000000000
--- a/problems/check-if-a-number-is-majority-element-in-a-sorted-array/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../article-views-ii "Article Views II")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-swaps-to-group-all-1s-together "Minimum Swaps to Group All 1's Together")
-
-## [1150. Check If a Number Is Majority Element in a Sorted Array (Easy)](https://leetcode.com/problems/check-if-a-number-is-majority-element-in-a-sorted-array "检查一个数是否在数组中占绝大多数")
-
-<p>Given an array <code>nums</code> sorted in <strong>non-decreasing</strong> order, and a number <code>target</code>, return <code>True</code> if and only if <code>target</code> is a majority element.</p>
-
-<p>A <em>majority element</em> is an element that appears <strong>more than <code>N/2</code></strong> times in an array of length <code>N</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>nums = <span id="example-input-1-1">[2,4,5,5,5,5,5,6,6]</span>, target = <span id="example-input-1-2">5</span>
-<strong>Output: </strong><span id="example-output-1">true</span>
-<strong>Explanation: </strong>
-The value 5 appears 5 times and the length of the array is 9.
-Thus, 5 is a majority element because 5 &gt; 9/2 is true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>nums = <span id="example-input-2-1">[10,100,101,101]</span>, target = <span id="example-input-2-2">101</span>
-<strong>Output: </strong><span id="example-output-2">false</span>
-<strong>Explanation: </strong>
-The value 101 appears 2 times and the length of the array is 4.
-Thus, 101 is not a majority element because 2 &gt; 4/2 is false.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><span><strong>Note:</strong></span></p>
-
-<ol>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10^9</code></li>
-	<li><code>1 &lt;= target &lt;= 10^9</code></li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Majority Element](../majority-element) (Easy)
-  1. [Majority Element II](../majority-element-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to check if a given number target is a majority element?.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the frequency of target and compare it to the length of the array.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can find the frequency of an element using Binary Search since the array is sorted.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Using Binary Search, find the first and last occurrences of A. Then just calculate the difference between the indexes of these occurrences.
-</details>
diff --git a/problems/check-if-a-parentheses-string-can-be-valid/README.md b/problems/check-if-a-parentheses-string-can-be-valid/README.md
deleted file mode 100644
index 9145e429f..000000000
--- a/problems/check-if-a-parentheses-string-can-be-valid/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-all-possible-recipes-from-given-supplies "Find All Possible Recipes from Given Supplies")
-　　　　　　　　　　　　　　　　
-[Next >](../abbreviating-the-product-of-a-range "Abbreviating the Product of a Range")
-
-## [2116. Check if a Parentheses String Can Be Valid (Medium)](https://leetcode.com/problems/check-if-a-parentheses-string-can-be-valid "判断一个括号字符串是否有效")
-
-<p>A parentheses string is a <strong>non-empty</strong> string consisting only of <code>&#39;(&#39;</code> and <code>&#39;)&#39;</code>. It is valid if <strong>any</strong> of the following conditions is <strong>true</strong>:</p>
-
-<ul>
-	<li>It is <code>()</code>.</li>
-	<li>It can be written as <code>AB</code> (<code>A</code> concatenated with <code>B</code>), where <code>A</code> and <code>B</code> are valid parentheses strings.</li>
-	<li>It can be written as <code>(A)</code>, where <code>A</code> is a valid parentheses string.</li>
-</ul>
-
-<p>You are given a parentheses string <code>s</code> and a string <code>locked</code>, both of length <code>n</code>. <code>locked</code> is a binary string consisting only of <code>&#39;0&#39;</code>s and <code>&#39;1&#39;</code>s. For <strong>each</strong> index <code>i</code> of <code>locked</code>,</p>
-
-<ul>
-	<li>If <code>locked[i]</code> is <code>&#39;1&#39;</code>, you <strong>cannot</strong> change <code>s[i]</code>.</li>
-	<li>But if <code>locked[i]</code> is <code>&#39;0&#39;</code>, you <strong>can</strong> change <code>s[i]</code> to either <code>&#39;(&#39;</code> or <code>&#39;)&#39;</code>.</li>
-</ul>
-
-<p>Return <code>true</code> <em>if you can make <code>s</code> a valid parentheses string</em>. Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/06/eg1.png" style="width: 311px; height: 101px;" />
-<pre>
-<strong>Input:</strong> s = &quot;))()))&quot;, locked = &quot;010100&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> locked[1] == &#39;1&#39; and locked[3] == &#39;1&#39;, so we cannot change s[1] or s[3].
-We change s[0] and s[4] to &#39;(&#39; while leaving s[2] and s[5] unchanged to make s valid.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;()()&quot;, locked = &quot;0000&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We do not need to make any changes because s is already valid.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;)&quot;, locked = &quot;0&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> locked permits us to change s[0]. 
-Changing s[0] to either &#39;(&#39; or &#39;)&#39; will not make s valid.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == s.length == locked.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;(&#39;</code> or <code>&#39;)&#39;</code>.</li>
-	<li><code>locked[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can an odd length string ever be valid?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-From left to right, if a locked ')' is encountered, it must be balanced with either a locked '(' or an unlocked index on its left. If neither exist, what conclusion can be drawn? If both exist, which one is more preferable to use?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-After the above, we may have locked indices of '(' and additional unlocked indices. How can you balance out the locked '(' now? What if you cannot balance any locked '('?
-</details>
diff --git a/problems/check-if-a-string-can-break-another-string/README.md b/problems/check-if-a-string-can-break-another-string/README.md
deleted file mode 100644
index 967b846b1..000000000
--- a/problems/check-if-a-string-can-break-another-string/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-difference-you-can-get-from-changing-an-integer "Max Difference You Can Get From Changing an Integer")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-wear-different-hats-to-each-other "Number of Ways to Wear Different Hats to Each Other")
-
-## [1433. Check If a String Can Break Another String (Medium)](https://leetcode.com/problems/check-if-a-string-can-break-another-string "检查一个字符串是否可以打破另一个字符串")
-
-<p>Given two strings: <code>s1</code> and <code>s2</code> with the same&nbsp;size, check if some&nbsp;permutation of string <code>s1</code> can break&nbsp;some&nbsp;permutation of string <code>s2</code> or vice-versa. In other words <code>s2</code> can break <code>s1</code>&nbsp;or vice-versa.</p>
-
-<p>A string <code>x</code>&nbsp;can break&nbsp;string <code>y</code>&nbsp;(both of size <code>n</code>) if <code>x[i] &gt;= y[i]</code>&nbsp;(in alphabetical order)&nbsp;for all <code>i</code>&nbsp;between <code>0</code> and <code>n-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;abc&quot;, s2 = &quot;xya&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> &quot;ayx&quot; is a permutation of s2=&quot;xya&quot; which can break to string &quot;abc&quot; which is a permutation of s1=&quot;abc&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;abe&quot;, s2 = &quot;acd&quot;
-<strong>Output:</strong> false 
-<strong>Explanation:</strong> All permutations for s1=&quot;abe&quot; are: &quot;abe&quot;, &quot;aeb&quot;, &quot;bae&quot;, &quot;bea&quot;, &quot;eab&quot; and &quot;eba&quot; and all permutation for s2=&quot;acd&quot; are: &quot;acd&quot;, &quot;adc&quot;, &quot;cad&quot;, &quot;cda&quot;, &quot;dac&quot; and &quot;dca&quot;. However, there is not any permutation from s1 which can break some permutation from s2 and vice-versa.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;leetcodee&quot;, s2 = &quot;interview&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>s1.length == n</code></li>
-	<li><code>s2.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 10^5</code></li>
-	<li>All strings consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort both strings and then check if one of them can break the other.
-</details>
diff --git a/problems/check-if-a-string-contains-all-binary-codes-of-size-k/README.md b/problems/check-if-a-string-contains-all-binary-codes-of-size-k/README.md
deleted file mode 100644
index 1e1302333..000000000
--- a/problems/check-if-a-string-contains-all-binary-codes-of-size-k/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../make-two-arrays-equal-by-reversing-sub-arrays "Make Two Arrays Equal by Reversing Sub-arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../course-schedule-iv "Course Schedule IV")
-
-## [1461. Check If a String Contains All Binary Codes of Size K (Medium)](https://leetcode.com/problems/check-if-a-string-contains-all-binary-codes-of-size-k "检查一个字符串是否包含所有长度为 K 的二进制子串")
-
-<p>Given a binary string <code>s</code> and an integer <code>k</code>, return <code>true</code> <em>if every binary code of length</em> <code>k</code> <em>is a substring of</em> <code>s</code>. Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;00110110&quot;, k = 2
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The binary codes of length 2 are &quot;00&quot;, &quot;01&quot;, &quot;10&quot; and &quot;11&quot;. They can be all found as substrings at indices 0, 1, 3 and 2 respectively.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0110&quot;, k = 1
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The binary codes of length 1 are &quot;0&quot; and &quot;1&quot;, it is clear that both exist as a substring. 
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0110&quot;, k = 2
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The binary code &quot;00&quot; is of length 2 and does not exist in the array.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 5 * 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-	<li><code>1 &lt;= k &lt;= 20</code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We need only to check all sub-strings of length k.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The number of distinct sub-strings should be exactly 2^k.
-</details>
diff --git a/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree/README.md b/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree/README.md
deleted file mode 100644
index 82be2ec2f..000000000
--- a/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree/README.md
+++ /dev/null
@@ -1,31 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../first-unique-number "First Unique Number")
-　　　　　　　　　　　　　　　　
-[Next >](../kids-with-the-greatest-number-of-candies "Kids With the Greatest Number of Candies")
-
-## [1430. Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree (Medium)](https://leetcode.com/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree "判断给定的序列是否是二叉树从根到叶的路径")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Depth-first search (DFS) with the parameters: current node in the binary tree and current position in the array of integers.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When reaching at final position check if it is a leaf node.
-</details>
diff --git a/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/README.md b/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/README.md
deleted file mode 100644
index 95c2506ca..000000000
--- a/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../active-users "Active Users")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-vowels-in-a-substring-of-given-length "Maximum Number of Vowels in a Substring of Given Length")
-
-## [1455. Check If a Word Occurs As a Prefix of Any Word in a Sentence (Easy)](https://leetcode.com/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence "检查单词是否为句中其他单词的前缀")
-
-<p>Given a <code>sentence</code> that consists of some words separated by a <strong>single space</strong>, and a <code>searchWord</code>, check if <code>searchWord</code> is a prefix of any word in <code>sentence</code>.</p>
-
-<p>Return <em>the index of the word in </em><code>sentence</code><em> (<strong>1-indexed</strong>) where </em><code>searchWord</code><em> is a prefix of this word</em>. If <code>searchWord</code> is a prefix of more than one word, return the index of the first word <strong>(minimum index)</strong>. If there is no such word return <code>-1</code>.</p>
-
-<p>A <strong>prefix</strong> of a string <code>s</code> is any leading contiguous substring of <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence = &quot;i love eating burger&quot;, searchWord = &quot;burg&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> &quot;burg&quot; is prefix of &quot;burger&quot; which is the 4th word in the sentence.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence = &quot;this problem is an easy problem&quot;, searchWord = &quot;pro&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> &quot;pro&quot; is prefix of &quot;problem&quot; which is the 2nd and the 6th word in the sentence, but we return 2 as it&#39;s the minimal index.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence = &quot;i am tired&quot;, searchWord = &quot;you&quot;
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> &quot;you&quot; is not a prefix of any word in the sentence.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= sentence.length &lt;= 100</code></li>
-	<li><code>1 &lt;= searchWord.length &lt;= 10</code></li>
-	<li><code>sentence</code> consists of lowercase English letters and spaces.</li>
-	<li><code>searchWord</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First extract the words of the sentence.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check for each word if searchWord occurs at index 0, if so return the index of this word (1-indexed)
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If searchWord doesn't exist as a prefix of any word return the default value (-1).
-</details>
diff --git a/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/check_if_a_word_occurs_as_a_prefix_of_any_word_in_a_sentence.go b/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/check_if_a_word_occurs_as_a_prefix_of_any_word_in_a_sentence.go
deleted file mode 100644
index 703b7c628..000000000
--- a/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/check_if_a_word_occurs_as_a_prefix_of_any_word_in_a_sentence.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem1455
-
-import "strings"
-
-func isPrefixOfWord(sentence string, searchWord string) int {
-	items := strings.Fields(sentence)
-	for i, item := range items {
-		if strings.HasPrefix(item, searchWord) {
-			return i + 1
-		}
-	}
-	return -1
-}
diff --git a/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/check_if_a_word_occurs_as_a_prefix_of_any_word_in_a_sentence_test.go b/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/check_if_a_word_occurs_as_a_prefix_of_any_word_in_a_sentence_test.go
deleted file mode 100644
index 30813227d..000000000
--- a/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/check_if_a_word_occurs_as_a_prefix_of_any_word_in_a_sentence_test.go
+++ /dev/null
@@ -1,45 +0,0 @@
-package problem1455
-
-import "testing"
-
-type testType struct {
-	sentence   string
-	searchWord string
-	want       int
-}
-
-func TestIsPrefixOfWord(t *testing.T) {
-	tests := [...]testType{
-		{
-			sentence:   "i love eating burger",
-			searchWord: "burg",
-			want:       4,
-		},
-		{
-			sentence:   "this problem is an easy problem",
-			searchWord: "pro",
-			want:       2,
-		},
-		{
-			sentence:   "i am tired",
-			searchWord: "you",
-			want:       -1,
-		},
-		{
-			sentence:   "i use triple pillow",
-			searchWord: "pill",
-			want:       4,
-		},
-		{
-			sentence:   "hello from the other side",
-			searchWord: "they",
-			want:       -1,
-		},
-	}
-	for _, tt := range tests {
-		got := isPrefixOfWord(tt.sentence, tt.searchWord)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.sentence, got, tt.want)
-		}
-	}
-}
diff --git a/problems/check-if-all-1s-are-at-least-length-k-places-away/README.md b/problems/check-if-all-1s-are-at-least-length-k-places-away/README.md
deleted file mode 100644
index 7e7b72d6f..000000000
--- a/problems/check-if-all-1s-are-at-least-length-k-places-away/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../destination-city "Destination City")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit "Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit")
-
-## [1437. Check If All 1's Are at Least Length K Places Away (Easy)](https://leetcode.com/problems/check-if-all-1s-are-at-least-length-k-places-away "是否所有 1 都至少相隔 k 个元素")
-
-<p>Given an array <code>nums</code> of 0s and 1s and an integer <code>k</code>, return <code>True</code> if all 1&#39;s are at least <code>k</code> places away from each other, otherwise return <code>False</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/04/15/sample_1_1791.png" style="width: 214px; height: 90px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,0,0,0,1,0,0,1], k = 2
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Each of the 1s are at least 2 places away from each other.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/04/15/sample_2_1791.png" style="width: 160px; height: 86px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,0,0,1,0,1], k = 2
-<strong>Output:</strong> false
-<strong>Explanation: </strong>The second 1 and third 1 are only one apart from each other.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,1,1], k = 0
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,0,1], k = 1
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= k &lt;= nums.length</code></li>
-	<li><code>nums[i]</code> is <code>0</code> or <code>1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Each time you find a number 1, check whether or not it is K or more places away from the next one. If it's not, return false.
-</details>
diff --git a/problems/check-if-all-as-appears-before-all-bs/README.md b/problems/check-if-all-as-appears-before-all-bs/README.md
deleted file mode 100644
index a5c03bdf8..000000000
--- a/problems/check-if-all-as-appears-before-all-bs/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-operations-to-remove-adjacent-ones-in-matrix "Minimum Operations to Remove Adjacent Ones in Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-laser-beams-in-a-bank "Number of Laser Beams in a Bank")
-
-## [2124. Check if All A's Appears Before All B's (Easy)](https://leetcode.com/problems/check-if-all-as-appears-before-all-bs "检查是否所有 A 都在 B 之前")
-
-<p>Given a string <code>s</code> consisting of <strong>only</strong> the characters <code>&#39;a&#39;</code> and <code>&#39;b&#39;</code>, return <code>true</code> <em>if <strong>every</strong> </em><code>&#39;a&#39;</code> <em>appears before <strong>every</strong> </em><code>&#39;b&#39;</code><em> in the string</em>. Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaabbb&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-The &#39;a&#39;s are at indices 0, 1, and 2, while the &#39;b&#39;s are at indices 3, 4, and 5.
-Hence, every &#39;a&#39; appears before every &#39;b&#39; and we return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abab&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-There is an &#39;a&#39; at index 2 and a &#39;b&#39; at index 1.
-Hence, not every &#39;a&#39; appears before every &#39;b&#39; and we return false.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bbb&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-There are no &#39;a&#39;s, hence, every &#39;a&#39; appears before every &#39;b&#39; and we return true.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s[i]</code> is either <code>&#39;a&#39;</code> or <code>&#39;b&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can check the opposite: check if there is a ‘b’ before an ‘a’. Then, negate and return that answer.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-s should not have any occurrences of “ba” as a substring.
-</details>
diff --git a/problems/check-if-all-characters-have-equal-number-of-occurrences/README.md b/problems/check-if-all-characters-have-equal-number-of-occurrences/README.md
deleted file mode 100644
index aacdbbaa9..000000000
--- a/problems/check-if-all-characters-have-equal-number-of-occurrences/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-common-subsequence-between-sorted-arrays "Longest Common Subsequence Between Sorted Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-the-smallest-unoccupied-chair "The Number of the Smallest Unoccupied Chair")
-
-## [1941. Check if All Characters Have Equal Number of Occurrences (Easy)](https://leetcode.com/problems/check-if-all-characters-have-equal-number-of-occurrences "检查是否所有字符出现次数相同")
-
-<p>Given a string <code>s</code>, return <code>true</code><em> if </em><code>s</code><em> is a <strong>good</strong> string, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>A string <code>s</code> is <strong>good</strong> if <strong>all</strong> the characters that appear in <code>s</code> have the <strong>same</strong> number of occurrences (i.e., the same frequency).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abacbc&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The characters that appear in s are &#39;a&#39;, &#39;b&#39;, and &#39;c&#39;. All characters occur 2 times in s.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaabb&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The characters that appear in s are &#39;a&#39; and &#39;b&#39;.
-&#39;a&#39; occurs 3 times while &#39;b&#39; occurs 2 times, which is not the same number of times.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Rings and Rods](../rings-and-rods) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build a dictionary containing the frequency of each character appearing in s
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check if all values in the dictionary are the same.
-</details>
diff --git a/problems/check-if-all-the-integers-in-a-range-are-covered/README.md b/problems/check-if-all-the-integers-in-a-range-are-covered/README.md
deleted file mode 100644
index d12d6aad3..000000000
--- a/problems/check-if-all-the-integers-in-a-range-are-covered/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../page-recommendations-ii "Page Recommendations II")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-student-that-will-replace-the-chalk "Find the Student that Will Replace the Chalk")
-
-## [1893. Check if All the Integers in a Range Are Covered (Easy)](https://leetcode.com/problems/check-if-all-the-integers-in-a-range-are-covered "检查是否区域内所有整数都被覆盖")
-
-<p>You are given a 2D integer array <code>ranges</code> and two integers <code>left</code> and <code>right</code>. Each <code>ranges[i] = [start<sub>i</sub>, end<sub>i</sub>]</code> represents an <strong>inclusive</strong> interval between <code>start<sub>i</sub></code> and <code>end<sub>i</sub></code>.</p>
-
-<p>Return <code>true</code> <em>if each integer in the inclusive range</em> <code>[left, right]</code> <em>is covered by <strong>at least one</strong> interval in</em> <code>ranges</code>. Return <code>false</code> <em>otherwise</em>.</p>
-
-<p>An integer <code>x</code> is covered by an interval <code>ranges[i] = [start<sub>i</sub>, end<sub>i</sub>]</code> if <code>start<sub>i</sub> &lt;= x &lt;= end<sub>i</sub></code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> ranges = [[1,2],[3,4],[5,6]], left = 2, right = 5
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Every integer between 2 and 5 is covered:
-- 2 is covered by the first range.
-- 3 and 4 are covered by the second range.
-- 5 is covered by the third range.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> ranges = [[1,10],[10,20]], left = 21, right = 21
-<strong>Output:</strong> false
-<strong>Explanation:</strong> 21 is not covered by any range.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= ranges.length &lt;= 50</code></li>
-	<li><code>1 &lt;= start<sub>i</sub> &lt;= end<sub>i</sub> &lt;= 50</code></li>
-	<li><code>1 &lt;= left &lt;= right &lt;= 50</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate over every integer point in the range [left, right].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each of these points check if it is included in one of the ranges.
-</details>
diff --git a/problems/check-if-an-original-string-exists-given-two-encoded-strings/README.md b/problems/check-if-an-original-string-exists-given-two-encoded-strings/README.md
deleted file mode 100644
index caeebf97b..000000000
--- a/problems/check-if-an-original-string-exists-given-two-encoded-strings/README.md
+++ /dev/null
@@ -1,109 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-operations-to-convert-number "Minimum Operations to Convert Number")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-spaces-cleaning-robot-cleaned "Number of Spaces Cleaning Robot Cleaned")
-
-## [2060. Check if an Original String Exists Given Two Encoded Strings (Hard)](https://leetcode.com/problems/check-if-an-original-string-exists-given-two-encoded-strings "同源字符串检测")
-
-<p>An original string, consisting of lowercase English letters, can be encoded by the following steps:</p>
-
-<ul>
-	<li>Arbitrarily <strong>split</strong> it into a <strong>sequence</strong> of some number of <strong>non-empty</strong> substrings.</li>
-	<li>Arbitrarily choose some elements (possibly none) of the sequence, and <strong>replace</strong> each with <strong>its length</strong> (as a numeric string).</li>
-	<li><strong>Concatenate</strong> the sequence as the encoded string.</li>
-</ul>
-
-<p>For example, <strong>one way</strong> to encode an original string <code>&quot;abcdefghijklmnop&quot;</code> might be:</p>
-
-<ul>
-	<li>Split it as a sequence: <code>[&quot;ab&quot;, &quot;cdefghijklmn&quot;, &quot;o&quot;, &quot;p&quot;]</code>.</li>
-	<li>Choose the second and third elements to be replaced by their lengths, respectively. The sequence becomes <code>[&quot;ab&quot;, &quot;12&quot;, &quot;1&quot;, &quot;p&quot;]</code>.</li>
-	<li>Concatenate the elements of the sequence to get the encoded string: <code>&quot;ab121p&quot;</code>.</li>
-</ul>
-
-<p>Given two encoded strings <code>s1</code> and <code>s2</code>, consisting of lowercase English letters and digits <code>1-9</code> (inclusive), return <code>true</code><em> if there exists an original string that could be encoded as <strong>both</strong> </em><code>s1</code><em> and </em><code>s2</code><em>. Otherwise, return </em><code>false</code>.</p>
-
-<p><strong>Note</strong>: The test cases are generated such that the number of consecutive digits in <code>s1</code> and <code>s2</code> does not exceed <code>3</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;internationalization&quot;, s2 = &quot;i18n&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> It is possible that &quot;internationalization&quot; was the original string.
-- &quot;internationalization&quot; 
-  -&gt; Split:       [&quot;internationalization&quot;]
-  -&gt; Do not replace any element
-  -&gt; Concatenate:  &quot;internationalization&quot;, which is s1.
-- &quot;internationalization&quot;
-  -&gt; Split:       [&quot;i&quot;, &quot;nternationalizatio&quot;, &quot;n&quot;]
-  -&gt; Replace:     [&quot;i&quot;, &quot;18&quot;,                 &quot;n&quot;]
-  -&gt; Concatenate:  &quot;i18n&quot;, which is s2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;l123e&quot;, s2 = &quot;44&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> It is possible that &quot;leetcode&quot; was the original string.
-- &quot;leetcode&quot; 
-  -&gt; Split:      [&quot;l&quot;, &quot;e&quot;, &quot;et&quot;, &quot;cod&quot;, &quot;e&quot;]
-  -&gt; Replace:    [&quot;l&quot;, &quot;1&quot;, &quot;2&quot;,  &quot;3&quot;,   &quot;e&quot;]
-  -&gt; Concatenate: &quot;l123e&quot;, which is s1.
-- &quot;leetcode&quot; 
-  -&gt; Split:      [&quot;leet&quot;, &quot;code&quot;]
-  -&gt; Replace:    [&quot;4&quot;,    &quot;4&quot;]
-  -&gt; Concatenate: &quot;44&quot;, which is s2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;a5b&quot;, s2 = &quot;c5b&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible.
-- The original string encoded as s1 must start with the letter &#39;a&#39;.
-- The original string encoded as s2 must start with the letter &#39;c&#39;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s1.length, s2.length &lt;= 40</code></li>
-	<li><code>s1</code> and <code>s2</code> consist of digits <code>1-9</code> (inclusive), and lowercase English letters only.</li>
-	<li>The number of consecutive digits in <code>s1</code> and <code>s2</code> does not exceed <code>3</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For s1 and s2, divide each into a sequence of single alphabet strings and digital strings. The problem now becomes comparing if two sequences are equal.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-A single alphabet string has no variation, but a digital string has variations. For example: "124" can be interpreted as 1+2+4, 12+4, 1+24, and 124 wildcard characters.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-There are four kinds of comparisons: a single alphabet vs another; a single alphabet vs a number, a number vs a single alphabet, and a number vs another number. In the case of a number vs another (a single alphabet or a number), can you decrease the number by the min length of both?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-There is a recurrence relation in the search which ends when either a single alphabet != another, or one sequence ran out, or both sequences ran out.
-</details>
diff --git a/problems/check-if-array-is-sorted-and-rotated/README.md b/problems/check-if-array-is-sorted-and-rotated/README.md
deleted file mode 100644
index 0db6947c5..000000000
--- a/problems/check-if-array-is-sorted-and-rotated/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-events-that-can-be-attended-ii "Maximum Number of Events That Can Be Attended II")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-score-from-removing-stones "Maximum Score From Removing Stones")
-
-## [1752. Check if Array Is Sorted and Rotated (Easy)](https://leetcode.com/problems/check-if-array-is-sorted-and-rotated "检查数组是否经排序和轮转得到")
-
-<p>Given an array <code>nums</code>, return <code>true</code><em> if the array was originally sorted in non-decreasing order, then rotated <strong>some</strong> number of positions (including zero)</em>. Otherwise, return <code>false</code>.</p>
-
-<p>There may be <strong>duplicates</strong> in the original array.</p>
-
-<p><strong>Note:</strong> An array <code>A</code> rotated by <code>x</code> positions results in an array <code>B</code> of the same length such that <code>A[i] == B[(i+x) % A.length]</code>, where <code>%</code> is the modulo operation.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,4,5,1,2]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> [1,2,3,4,5] is the original sorted array.
-You can rotate the array by x = 3 positions to begin on the the element of value 3: [3,4,5,1,2].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,3,4]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There is no sorted array once rotated that can make nums.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> [1,2,3] is the original sorted array.
-You can rotate the array by x = 0 positions (i.e. no rotation) to make nums.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Brute force and check if it is possible for a sorted array to start from each position.
-</details>
diff --git a/problems/check-if-array-pairs-are-divisible-by-k/README.md b/problems/check-if-array-pairs-are-divisible-by-k/README.md
deleted file mode 100644
index 2eeb96e92..000000000
--- a/problems/check-if-array-pairs-are-divisible-by-k/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-crossing "Path Crossing")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-subsequences-that-satisfy-the-given-sum-condition "Number of Subsequences That Satisfy the Given Sum Condition")
-
-## [1497. Check If Array Pairs Are Divisible by k (Medium)](https://leetcode.com/problems/check-if-array-pairs-are-divisible-by-k "检查数组对是否可以被 k 整除")
-
-<p>Given an array of integers <code>arr</code> of even length <code>n</code> and an integer <code>k</code>.</p>
-
-<p>We want to divide the array into exactly <code>n / 2</code> pairs such that the sum of each pair is divisible by <code>k</code>.</p>
-
-<p>Return <code>true</code><em> If you can find a way to do that or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4,5,10,6,7,8,9], k = 5
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Pairs are (1,9),(2,8),(3,7),(4,6) and (5,10).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4,5,6], k = 7
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Pairs are (1,6),(2,5) and(3,4).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4,5,6], k = 10
-<strong>Output:</strong> false
-<strong>Explanation:</strong> You can try all possible pairs to see that there is no way to divide arr into 3 pairs each with sum divisible by 10.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>arr.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>n</code> is even.</li>
-	<li><code>-10<sup>9</sup> &lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep an array of the frequencies of ((x % k) + k) % k for each x in arr.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-for each i in [0, k - 1] we need to check if freq[k] == freq[k - i]
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Take care of the case when i == k - i and when i == 0
-</details>
diff --git a/problems/check-if-binary-string-has-at-most-one-segment-of-ones/README.md b/problems/check-if-binary-string-has-at-most-one-segment-of-ones/README.md
deleted file mode 100644
index 60756572a..000000000
--- a/problems/check-if-binary-string-has-at-most-one-segment-of-ones/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../grand-slam-titles "Grand Slam Titles")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-elements-to-add-to-form-a-given-sum "Minimum Elements to Add to Form a Given Sum")
-
-## [1784. Check if Binary String Has at Most One Segment of Ones (Easy)](https://leetcode.com/problems/check-if-binary-string-has-at-most-one-segment-of-ones "检查二进制字符串字段")
-
-<p>Given a binary string <code>s</code> <strong>​​​​​without leading zeros</strong>, return <code>true</code>​​​ <em>if </em><code>s</code><em> contains <strong>at most one contiguous segment of ones</strong></em>. Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1001&quot;
-<strong>Output:</strong> false
-<strong>Explanation: </strong>The ones do not form a contiguous segment.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;110&quot;
-<strong>Output:</strong> true</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s[i]</code>​​​​ is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-	<li><code>s[0]</code> is&nbsp;<code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Longer Contiguous Segments of Ones than Zeros](../longer-contiguous-segments-of-ones-than-zeros) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-It's guaranteed to have at least one segment
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The string size is small so you can count all segments of ones with no that have no adjacent ones.
-</details>
diff --git a/problems/check-if-every-row-and-column-contains-all-numbers/README.md b/problems/check-if-every-row-and-column-contains-all-numbers/README.md
deleted file mode 100644
index b3597801f..000000000
--- a/problems/check-if-every-row-and-column-contains-all-numbers/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stamping-the-grid "Stamping the Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-swaps-to-group-all-1s-together-ii "Minimum Swaps to Group All 1's Together II")
-
-## [2133. Check if Every Row and Column Contains All Numbers (Easy)](https://leetcode.com/problems/check-if-every-row-and-column-contains-all-numbers "检查是否每一行每一列都包含全部整数")
-
-<p>An <code>n x n</code> matrix is <strong>valid</strong> if every row and every column contains <strong>all</strong> the integers from <code>1</code> to <code>n</code> (<strong>inclusive</strong>).</p>
-
-<p>Given an <code>n x n</code> integer matrix <code>matrix</code>, return <code>true</code> <em>if the matrix is <strong>valid</strong>.</em> Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/21/example1drawio.png" style="width: 250px; height: 251px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,2,3],[3,1,2],[2,3,1]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> In this case, n = 3, and every row and column contains the numbers 1, 2, and 3.
-Hence, we return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/21/example2drawio.png" style="width: 250px; height: 251px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,1,1],[1,2,3],[1,2,3]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> In this case, n = 3, but the first row and the first column do not contain the numbers 2 or 3.
-Hence, we return false.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == matrix.length == matrix[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= matrix[i][j] &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use for loops to check each row for every number from 1 to n. Similarly, do the same for each column.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each check, you can keep a set of the unique elements in the checked row/col. By the end of the check, the size of the set should be n.
-</details>
diff --git a/problems/check-if-it-is-a-good-array/README.md b/problems/check-if-it-is-a-good-array/README.md
deleted file mode 100644
index 289c87eae..000000000
--- a/problems/check-if-it-is-a-good-array/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-remove-to-make-valid-parentheses "Minimum Remove to Make Valid Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../average-selling-price "Average Selling Price")
-
-## [1250. Check If It Is a Good Array (Hard)](https://leetcode.com/problems/check-if-it-is-a-good-array "检查「好数组」")
-
-<p>Given an array <code>nums</code> of&nbsp;positive integers. Your task is to select some subset of <code>nums</code>, multiply each element by an integer and add all these numbers.&nbsp;The array is said to be&nbsp;<strong>good&nbsp;</strong>if you can obtain a sum of&nbsp;<code>1</code>&nbsp;from the array by any possible subset and multiplicand.</p>
-
-<p>Return&nbsp;<code>True</code>&nbsp;if the array is <strong>good&nbsp;</strong>otherwise&nbsp;return&nbsp;<code>False</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [12,5,7,23]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Pick numbers 5 and 7.
-5*3 + 7*(-2) = 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [29,6,10]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Pick numbers 29, 6 and 10.
-29*1 + 6*(-3) + 10*(-1) = 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,6]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10^5</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Number Theory](../../tag/number-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Eq.  ax+by=1 has solution x, y if gcd(a,b) = 1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you generalize the formula?.  Check Bézout's lemma.
-</details>
diff --git a/problems/check-if-it-is-a-straight-line/README.md b/problems/check-if-it-is-a-straight-line/README.md
deleted file mode 100644
index f56c7a5e8..000000000
--- a/problems/check-if-it-is-a-straight-line/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../divide-chocolate "Divide Chocolate")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-sub-folders-from-the-filesystem "Remove Sub-Folders from the Filesystem")
-
-## [1232. Check If It Is a Straight Line (Easy)](https://leetcode.com/problems/check-if-it-is-a-straight-line "缀点成线")
-
-<p>You are given an array&nbsp;<code>coordinates</code>, <code>coordinates[i] = [x, y]</code>, where <code>[x, y]</code> represents the coordinate of a point. Check if these points&nbsp;make a straight line in the XY plane.</p>
-
-<p>&nbsp;</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/15/untitled-diagram-2.jpg" style="width: 336px; height: 336px;" /></p>
-
-<pre>
-<strong>Input:</strong> coordinates = [[1,2],[2,3],[3,4],[4,5],[5,6],[6,7]]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/10/09/untitled-diagram-1.jpg" style="width: 348px; height: 336px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> coordinates = [[1,1],[2,2],[3,4],[4,5],[5,6],[7,7]]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;=&nbsp;coordinates.length &lt;= 1000</code></li>
-	<li><code>coordinates[i].length == 2</code></li>
-	<li><code>-10^4 &lt;=&nbsp;coordinates[i][0],&nbsp;coordinates[i][1] &lt;= 10^4</code></li>
-	<li><code>coordinates</code>&nbsp;contains no duplicate point.</li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If there're only 2 points, return true.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check if all other points lie on the line defined by the first 2 points.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use cross product to check collinearity.
-</details>
diff --git a/problems/check-if-move-is-legal/README.md b/problems/check-if-move-is-legal/README.md
deleted file mode 100644
index 026618369..000000000
--- a/problems/check-if-move-is-legal/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-characters-to-make-fancy-string "Delete Characters to Make Fancy String")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-total-space-wasted-with-k-resizing-operations "Minimum Total Space Wasted With K Resizing Operations")
-
-## [1958. Check if Move is Legal (Medium)](https://leetcode.com/problems/check-if-move-is-legal "检查操作是否合法")
-
-<p>You are given a <strong>0-indexed</strong> <code>8 x 8</code> grid <code>board</code>, where <code>board[r][c]</code> represents the cell <code>(r, c)</code> on a game board. On the board, free cells are represented by <code>&#39;.&#39;</code>, white cells are represented by <code>&#39;W&#39;</code>, and black cells are represented by <code>&#39;B&#39;</code>.</p>
-
-<p>Each move in this game consists of choosing a free cell and changing it to the color you are playing as (either white or black). However, a move is only <strong>legal</strong> if, after changing it, the cell becomes the <strong>endpoint of a good line</strong> (horizontal, vertical, or diagonal).</p>
-
-<p>A <strong>good line</strong> is a line of <strong>three or more cells (including the endpoints)</strong> where the endpoints of the line are <strong>one color</strong>, and the remaining cells in the middle are the <strong>opposite color</strong> (no cells in the line are free). You can find examples for good lines in the figure below:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/22/goodlines5.png" style="width: 500px; height: 312px;" />
-<p>Given two integers <code>rMove</code> and <code>cMove</code> and a character <code>color</code> representing the color you are playing as (white or black), return <code>true</code> <em>if changing cell </em><code>(rMove, cMove)</code> <em>to color</em> <code>color</code> <em>is a <strong>legal</strong> move, or </em><code>false</code><em> if it is not legal</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/10/grid11.png" style="width: 350px; height: 350px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;B&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;W&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;W&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;W&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;W&quot;,&quot;B&quot;,&quot;B&quot;,&quot;.&quot;,&quot;W&quot;,&quot;W&quot;,&quot;W&quot;,&quot;B&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;B&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;B&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;W&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]], rMove = 4, cMove = 3, color = &quot;B&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> &#39;.&#39;, &#39;W&#39;, and &#39;B&#39; are represented by the colors blue, white, and black respectively, and cell (rMove, cMove) is marked with an &#39;X&#39;.
-The two good lines with the chosen cell as an endpoint are annotated above with the red rectangles.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/10/grid2.png" style="width: 350px; height: 351px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;B&quot;,&quot;.&quot;,&quot;.&quot;,&quot;W&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;W&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;W&quot;,&quot;B&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;B&quot;,&quot;W&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;W&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;B&quot;]], rMove = 4, cMove = 4, color = &quot;W&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> While there are good lines with the chosen cell as a middle cell, there are no good lines with the chosen cell as an endpoint.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>board.length == board[r].length == 8</code></li>
-	<li><code>0 &lt;= rMove, cMove &lt; 8</code></li>
-	<li><code>board[rMove][cMove] == &#39;.&#39;</code></li>
-	<li><code>color</code> is either <code>&#39;B&#39;</code> or <code>&#39;W&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each line starting at the given cell check if it's a good line
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To do that iterate over all directions horizontal, vertical, and diagonals then check good lines naively
-</details>
diff --git a/problems/check-if-n-and-its-double-exist/README.md b/problems/check-if-n-and-its-double-exist/README.md
deleted file mode 100644
index c54a20cf5..000000000
--- a/problems/check-if-n-and-its-double-exist/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../jump-game-iv "Jump Game IV")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-steps-to-make-two-strings-anagram "Minimum Number of Steps to Make Two Strings Anagram")
-
-## [1346. Check If N and Its Double Exist (Easy)](https://leetcode.com/problems/check-if-n-and-its-double-exist "检查整数及其两倍数是否存在")
-
-<p>Given an array <code>arr</code> of integers, check if there exists two integers <code>N</code> and <code>M</code> such that <code>N</code> is the double of <code>M</code> ( i.e. <code>N = 2 * M</code>).</p>
-
-<p>More formally check if there exists&nbsp;two indices <code>i</code> and <code>j</code> such that :</p>
-
-<ul>
-	<li><code>i != j</code></li>
-	<li><code>0 &lt;= i, j &lt; arr.length</code></li>
-	<li><code>arr[i] == 2 * arr[j]</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [10,2,5,3]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> N<code> = 10</code> is the double of M<code> = 5</code>,that is, <code>10 = 2 * 5</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [7,1,14,11]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> N<code> = 14</code> is the double of M<code> = 7</code>,that is, <code>14 = 2 * 7</code>.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,1,7,11]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> In this case does not exist N and M, such that N = 2 * M.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr.length &lt;= 500</code></li>
-	<li><code>-10^3 &lt;= arr[i] &lt;= 10^3</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Keep Multiplying Found Values by Two](../keep-multiplying-found-values-by-two) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Loop from i = 0 to arr.length, maintaining in a hashTable the array elements from [0, i - 1].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-On each step of the loop check if we have seen the element 2 * arr[i] so far or arr[i] / 2 was seen if arr[i] % 2 == 0.
-</details>
diff --git a/problems/check-if-number-is-a-sum-of-powers-of-three/README.md b/problems/check-if-number-is-a-sum-of-powers-of-three/README.md
deleted file mode 100644
index 85e10f36c..000000000
--- a/problems/check-if-number-is-a-sum-of-powers-of-three/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-nearest-point-that-has-the-same-x-or-y-coordinate "Find Nearest Point That Has the Same X or Y Coordinate")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-beauty-of-all-substrings "Sum of Beauty of All Substrings")
-
-## [1780. Check if Number is a Sum of Powers of Three (Medium)](https://leetcode.com/problems/check-if-number-is-a-sum-of-powers-of-three "判断一个数字是否可以表示成三的幂的和")
-
-<p>Given an integer <code>n</code>, return <code>true</code> <em>if it is possible to represent </em><code>n</code><em> as the sum of distinct powers of three.</em> Otherwise, return <code>false</code>.</p>
-
-<p>An integer <code>y</code> is a power of three if there exists an integer <code>x</code> such that <code>y == 3<sup>x</sup></code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 12
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 12 = 3<sup>1</sup> + 3<sup>2</sup>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 91
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 91 = 3<sup>0</sup> + 3<sup>2</sup> + 3<sup>4</sup>
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 21
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's note that the maximum power of 3 you'll use in your soln is 3^16
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The number can not be represented as a sum of powers of 3 if it's ternary presentation has a 2 in it
-</details>
diff --git a/problems/check-if-numbers-are-ascending-in-a-sentence/README.md b/problems/check-if-numbers-are-ascending-in-a-sentence/README.md
deleted file mode 100644
index f23398623..000000000
--- a/problems/check-if-numbers-are-ascending-in-a-sentence/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../accepted-candidates-from-the-interviews "Accepted Candidates From the Interviews")
-　　　　　　　　　　　　　　　　
-[Next >](../simple-bank-system "Simple Bank System")
-
-## [2042. Check if Numbers Are Ascending in a Sentence (Easy)](https://leetcode.com/problems/check-if-numbers-are-ascending-in-a-sentence "检查句子中的数字是否递增")
-
-<p>A sentence is a list of <strong>tokens</strong> separated by a <strong>single</strong> space with no leading or trailing spaces. Every token is either a <strong>positive number</strong> consisting of digits <code>0-9</code> with no leading zeros, or a <strong>word</strong> consisting of lowercase English letters.</p>
-
-<ul>
-	<li>For example, <code>&quot;a puppy has 2 eyes 4 legs&quot;</code> is a sentence with seven tokens: <code>&quot;2&quot;</code> and <code>&quot;4&quot;</code> are numbers and the other tokens such as <code>&quot;puppy&quot;</code> are words.</li>
-</ul>
-
-<p>Given a string <code>s</code> representing a sentence, you need to check if <strong>all</strong> the numbers in <code>s</code> are <strong>strictly increasing</strong> from left to right (i.e., other than the last number, <strong>each</strong> number is <strong>strictly smaller</strong> than the number on its <strong>right</strong> in <code>s</code>).</p>
-
-<p>Return <code>true</code><em> if so, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="example-1" src="https://assets.leetcode.com/uploads/2021/09/30/example1.png" style="width: 637px; height: 48px;" />
-<pre>
-<strong>Input:</strong> s = &quot;1 box has 3 blue 4 red 6 green and 12 yellow marbles&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The numbers in s are: 1, 3, 4, 6, 12.
-They are strictly increasing from left to right: 1 &lt; 3 &lt; 4 &lt; 6 &lt; 12.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;hello world 5 x 5&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The numbers in s are: <u><strong>5</strong></u>, <strong><u>5</u></strong>. They are not strictly increasing.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="example-3" src="https://assets.leetcode.com/uploads/2021/09/30/example3.png" style="width: 794px; height: 48px;" />
-<pre>
-<strong>Input:</strong> s = &quot;sunset is at 7 51 pm overnight lows will be in the low 50 and 60 s&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The numbers in s are: 7, <u><strong>51</strong></u>, <u><strong>50</strong></u>, 60. They are not strictly increasing.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= s.length &lt;= 200</code></li>
-	<li><code>s</code> consists of lowercase English letters, spaces, and digits from <code>0</code> to <code>9</code>, inclusive.</li>
-	<li>The number of tokens in <code>s</code> is between <code>2</code> and <code>100</code>, inclusive.</li>
-	<li>The tokens in <code>s</code> are separated by a single space.</li>
-	<li>There are at least <strong>two</strong> numbers in <code>s</code>.</li>
-	<li>Each number in <code>s</code> is a <strong>positive</strong> number <strong>less</strong> than <code>100</code>, with no leading zeros.</li>
-	<li><code>s</code> contains no leading or trailing spaces.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use string tokenization of your language to extract all the tokens of the string easily.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each token extracted, how can you tell if it is a number? Does the first letter being a digit mean something?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Compare the number with the previously occurring number to check if ascending order is maintained.
-</details>
diff --git a/problems/check-if-one-string-swap-can-make-strings-equal/README.md b/problems/check-if-one-string-swap-can-make-strings-equal/README.md
deleted file mode 100644
index 97904c0b9..000000000
--- a/problems/check-if-one-string-swap-can-make-strings-equal/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../primary-department-for-each-employee "Primary Department for Each Employee")
-　　　　　　　　　　　　　　　　
-[Next >](../find-center-of-star-graph "Find Center of Star Graph")
-
-## [1790. Check if One String Swap Can Make Strings Equal (Easy)](https://leetcode.com/problems/check-if-one-string-swap-can-make-strings-equal "仅执行一次字符串交换能否使两个字符串相等")
-
-<p>You are given two strings <code>s1</code> and <code>s2</code> of equal length. A <strong>string swap</strong> is an operation where you choose two indices in a string (not necessarily different) and swap the characters at these indices.</p>
-
-<p>Return <code>true</code> <em>if it is possible to make both strings equal by performing <strong>at most one string swap </strong>on <strong>exactly one</strong> of the strings. </em>Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;bank&quot;, s2 = &quot;kanb&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> For example, swap the first character with the last character of s2 to make &quot;bank&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;attack&quot;, s2 = &quot;defend&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to make them equal with one string swap.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;kelb&quot;, s2 = &quot;kelb&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The two strings are already equal, so no string swap operation is required.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s1.length, s2.length &lt;= 100</code></li>
-	<li><code>s1.length == s2.length</code></li>
-	<li><code>s1</code> and <code>s2</code> consist of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Buddy Strings](../buddy-strings) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The answer is false if the number of nonequal positions in the strings is not equal to 0 or 2.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check that these positions have the same set of characters.
-</details>
diff --git a/problems/check-if-string-is-a-prefix-of-array/README.md b/problems/check-if-string-is-a-prefix-of-array/README.md
deleted file mode 100644
index 9bf0c41d0..000000000
--- a/problems/check-if-string-is-a-prefix-of-array/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-product-of-the-length-of-two-palindromic-substrings "Maximum Product of the Length of Two Palindromic Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-stones-to-minimize-the-total "Remove Stones to Minimize the Total")
-
-## [1961. Check If String Is a Prefix of Array (Easy)](https://leetcode.com/problems/check-if-string-is-a-prefix-of-array "检查字符串是否为数组前缀")
-
-<p>Given a string <code>s</code> and an array of strings <code>words</code>, determine whether <code>s</code> is a <strong>prefix string</strong> of <code>words</code>.</p>
-
-<p>A string <code>s</code> is a <strong>prefix string</strong> of <code>words</code> if <code>s</code> can be made by concatenating the first <code>k</code> strings in <code>words</code> for some <strong>positive</strong> <code>k</code> no larger than <code>words.length</code>.</p>
-
-<p>Return <code>true</code><em> if </em><code>s</code><em> is a <strong>prefix string</strong> of </em><code>words</code><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;iloveleetcode&quot;, words = [&quot;i&quot;,&quot;love&quot;,&quot;leetcode&quot;,&quot;apples&quot;]
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-s can be made by concatenating &quot;i&quot;, &quot;love&quot;, and &quot;leetcode&quot; together.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;iloveleetcode&quot;, words = [&quot;apples&quot;,&quot;i&quot;,&quot;love&quot;,&quot;leetcode&quot;]
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-It is impossible to make s using a prefix of arr.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 100</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 20</code></li>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>words[i]</code> and <code>s</code> consist of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There are only words.length prefix strings.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Create all of them and see if s is one of them.
-</details>
diff --git a/problems/check-if-string-is-decomposable-into-value-equal-substrings/README.md b/problems/check-if-string-is-decomposable-into-value-equal-substrings/README.md
deleted file mode 100644
index e984f649b..000000000
--- a/problems/check-if-string-is-decomposable-into-value-equal-substrings/README.md
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../merge-bsts-to-create-single-bst "Merge BSTs to Create Single BST")
-　　　　　　　　　　　　　　　　
-[Next >](../confirmation-rate "Confirmation Rate")
-
-## [1933. Check if String Is Decomposable Into Value-Equal Substrings (Easy)](https://leetcode.com/problems/check-if-string-is-decomposable-into-value-equal-substrings "判断字符串是否可分解为值均等的子串")
-
-
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep looking for 3-equals, if you find a 3-equal, keep going. If you don't find a 3-equal, check if it is a 2-equal.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Make sure that it is the only 2-equal.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If it is neither a 3-equal nor a 2-equal, then it is impossible.
-</details>
diff --git a/problems/check-if-string-is-transformable-with-substring-sort-operations/README.md b/problems/check-if-string-is-transformable-with-substring-sort-operations/README.md
deleted file mode 100644
index 59a65dbb5..000000000
--- a/problems/check-if-string-is-transformable-with-substring-sort-operations/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../min-cost-to-connect-all-points "Min Cost to Connect All Points")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-search-tree-iterator-ii "Binary Search Tree Iterator II")
-
-## [1585. Check If String Is Transformable With Substring Sort Operations (Hard)](https://leetcode.com/problems/check-if-string-is-transformable-with-substring-sort-operations "检查字符串是否可以通过排序子字符串得到另一个字符串")
-
-<p>Given two strings <code>s</code> and <code>t</code>, transform string <code>s</code> into string <code>t</code> using the following operation any number of times:</p>
-
-<ul>
-	<li>Choose a <strong>non-empty</strong> substring in <code>s</code> and sort it in place so the characters are in <strong>ascending order</strong>.
-	<ul>
-		<li>For example, applying the operation on the underlined substring in <code>&quot;1<u>4234</u>&quot;</code> results in <code>&quot;1<u>2344</u>&quot;</code>.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <code>true</code> if <em>it is possible to transform <code>s</code> into <code>t</code></em>. Otherwise, return <code>false</code>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;84532&quot;, t = &quot;34852&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can transform s into t using the following sort operations:
-&quot;84<u>53</u>2&quot; (from index 2 to 3) -&gt; &quot;84<u>35</u>2&quot;
-&quot;<u>843</u>52&quot; (from index 0 to 2) -&gt; &quot;<u>348</u>52&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;34521&quot;, t = &quot;23415&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can transform s into t using the following sort operations:
-&quot;<u>3452</u>1&quot; -&gt; &quot;<u>2345</u>1&quot;
-&quot;234<u>51</u>&quot; -&gt; &quot;234<u>15</u>&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;12345&quot;, t = &quot;12435&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>s.length == t.length</code></li>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> and <code>t</code> consist of only digits.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Suppose the first digit you need is 'd'. How can you determine if it's possible to get that digit there?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Consider swapping adjacent characters to maintain relative ordering.
-</details>
diff --git a/problems/check-if-the-sentence-is-pangram/README.md b/problems/check-if-the-sentence-is-pangram/README.md
deleted file mode 100644
index c937655c0..000000000
--- a/problems/check-if-the-sentence-is-pangram/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-transaction-each-day "Maximum Transaction Each Day")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-ice-cream-bars "Maximum Ice Cream Bars")
-
-## [1832. Check if the Sentence Is Pangram (Easy)](https://leetcode.com/problems/check-if-the-sentence-is-pangram "判断句子是否为全字母句")
-
-<p>A <strong>pangram</strong> is a sentence where every letter of the English alphabet appears at least once.</p>
-
-<p>Given a string <code>sentence</code> containing only lowercase English letters, return<em> </em><code>true</code><em> if </em><code>sentence</code><em> is a <strong>pangram</strong>, or </em><code>false</code><em> otherwise.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence = &quot;thequickbrownfoxjumpsoverthelazydog&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> sentence contains at least one of every letter of the English alphabet.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence = &quot;leetcode&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= sentence.length &lt;= 1000</code></li>
-	<li><code>sentence</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate over the string and mark each character as found (using a boolean array, bitmask, or any other similar way).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check if the number of found characters equals the alphabet length.
-</details>
diff --git a/problems/check-if-there-is-a-valid-path-in-a-grid/README.md b/problems/check-if-there-is-a-valid-path-in-a-grid/README.md
deleted file mode 100644
index 1efa3602a..000000000
--- a/problems/check-if-there-is-a-valid-path-in-a-grid/README.md
+++ /dev/null
@@ -1,97 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../four-divisors "Four Divisors")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-happy-prefix "Longest Happy Prefix")
-
-## [1391. Check if There is a Valid Path in a Grid (Medium)](https://leetcode.com/problems/check-if-there-is-a-valid-path-in-a-grid "检查网格中是否存在有效路径")
-
-Given a <em>m</em> x <em>n</em> <code>grid</code>. Each cell of the <code>grid</code> represents a street. The street of&nbsp;<code>grid[i][j]</code> can be:
-<ul>
-	<li><strong>1</strong> which means a street connecting the left cell and the right cell.</li>
-	<li><strong>2</strong> which means a street connecting the upper cell and the lower cell.</li>
-	<li><b>3</b>&nbsp;which means a street connecting the left cell and the lower cell.</li>
-	<li><b>4</b> which means a street connecting the right cell and the lower cell.</li>
-	<li><b>5</b> which means a street connecting the left cell and the upper cell.</li>
-	<li><b>6</b> which means a street connecting the right cell and the upper cell.</li>
-</ul>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/03/05/main.png" style="width: 450px; height: 708px;" /></p>
-
-<p>You will initially start at the street of the&nbsp;upper-left cell <code>(0,0)</code>. A valid path in the grid is a path which starts from the upper left&nbsp;cell <code>(0,0)</code> and ends at the bottom-right&nbsp;cell <code>(m - 1, n - 1)</code>. <strong>The path should only follow the streets</strong>.</p>
-
-<p><strong>Notice</strong> that you are <strong>not allowed</strong> to change any street.</p>
-
-<p>Return <i>true</i>&nbsp;if there is a valid path in the grid or <em>false</em> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/03/05/e1.png" style="width: 455px; height: 311px;" />
-<pre>
-<strong>Input:</strong> grid = [[2,4,3],[6,5,2]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> As shown you can start at cell (0, 0) and visit all the cells of the grid to reach (m - 1, n - 1).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/03/05/e2.png" style="width: 455px; height: 293px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,2,1],[1,2,1]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> As shown you the street at cell (0, 0) is not connected with any street of any other cell and you will get stuck at cell (0, 0)
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,2]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> You will get stuck at cell (0, 1) and you cannot reach cell (0, 2).
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,1,1,1,1,3]]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[2],[2],[2],[2],[2],[2],[6]]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 300</code></li>
-	<li><code>1 &lt;= grid[i][j] &lt;= 6</code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Start DFS from the node (0, 0) and follow the path till you stop.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When you reach a cell and cannot move anymore check that this cell is (m - 1, n - 1) or not.
-</details>
diff --git a/problems/check-if-two-expression-trees-are-equivalent/README.md b/problems/check-if-two-expression-trees-are-equivalent/README.md
deleted file mode 100644
index c25f72b60..000000000
--- a/problems/check-if-two-expression-trees-are-equivalent/README.md
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-one-bit-operations-to-make-integers-zero "Minimum One Bit Operations to Make Integers Zero")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-missing-ids "Find the Missing IDs")
-
-## [1612. Check If Two Expression Trees are Equivalent (Medium)](https://leetcode.com/problems/check-if-two-expression-trees-are-equivalent "检查两棵二叉表达式树是否等价")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Build Binary Expression Tree From Infix Expression](../build-binary-expression-tree-from-infix-expression) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count for each variable how many times it appeared in the first tree.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Do the same for the second tree and check if the count is the same for both tree.
-</details>
diff --git a/problems/check-if-two-string-arrays-are-equivalent/README.md b/problems/check-if-two-string-arrays-are-equivalent/README.md
deleted file mode 100644
index 4a4b7f734..000000000
--- a/problems/check-if-two-string-arrays-are-equivalent/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../average-time-of-process-per-machine "Average Time of Process per Machine")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-string-with-a-given-numeric-value "Smallest String With A Given Numeric Value")
-
-## [1662. Check If Two String Arrays are Equivalent (Easy)](https://leetcode.com/problems/check-if-two-string-arrays-are-equivalent "检查两个字符串数组是否相等")
-
-<p>Given two string arrays <code>word1</code> and <code>word2</code>, return<em> </em><code>true</code><em> if the two arrays <strong>represent</strong> the same string, and </em><code>false</code><em> otherwise.</em></p>
-
-<p>A string is <strong>represented</strong> by an array if the array elements concatenated <strong>in order</strong> forms the string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = [&quot;ab&quot;, &quot;c&quot;], word2 = [&quot;a&quot;, &quot;bc&quot;]
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-word1 represents string &quot;ab&quot; + &quot;c&quot; -&gt; &quot;abc&quot;
-word2 represents string &quot;a&quot; + &quot;bc&quot; -&gt; &quot;abc&quot;
-The strings are the same, so return true.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = [&quot;a&quot;, &quot;cb&quot;], word2 = [&quot;ab&quot;, &quot;c&quot;]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1  = [&quot;abc&quot;, &quot;d&quot;, &quot;defg&quot;], word2 = [&quot;abcddefg&quot;]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word1.length, word2.length &lt;= 10<sup>3</sup></code></li>
-	<li><code>1 &lt;= word1[i].length, word2[i].length &lt;= 10<sup>3</sup></code></li>
-	<li><code>1 &lt;= sum(word1[i].length), sum(word2[i].length) &lt;= 10<sup>3</sup></code></li>
-	<li><code>word1[i]</code> and <code>word2[i]</code> consist of lowercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Concatenate all strings in the first array into a single string in the given order, the same for the second array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Both arrays represent the same string if and only if the generated strings are the same.
-</details>
diff --git a/problems/check-if-two-string-arrays-are-equivalent/check_if_two_string_arrays_are_equivalent.go b/problems/check-if-two-string-arrays-are-equivalent/check_if_two_string_arrays_are_equivalent.go
deleted file mode 100644
index 2d596f45f..000000000
--- a/problems/check-if-two-string-arrays-are-equivalent/check_if_two_string_arrays_are_equivalent.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem1662
-
-import "strings"
-
-func arrayStringsAreEqual(word1 []string, word2 []string) bool {
-	str1 := strings.Builder{}
-	for _, s := range word1 {
-		str1.WriteString(s)
-	}
-	str2 := strings.Builder{}
-	for _, s := range word2 {
-		str2.WriteString(s)
-	}
-	return str1.String() == str2.String()
-}
diff --git a/problems/check-if-two-string-arrays-are-equivalent/check_if_two_string_arrays_are_equivalent_test.go b/problems/check-if-two-string-arrays-are-equivalent/check_if_two_string_arrays_are_equivalent_test.go
deleted file mode 100644
index 7fa5a0486..000000000
--- a/problems/check-if-two-string-arrays-are-equivalent/check_if_two_string_arrays_are_equivalent_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1662
-
-import "testing"
-
-type testType struct {
-	word1 []string
-	word2 []string
-	want  bool
-}
-
-func TestArrayStringsAreEqual(t *testing.T) {
-	tests := [...]testType{
-		{
-			word1: []string{"ab", "c"},
-			word2: []string{"a", "bc"},
-			want:  true,
-		},
-		{
-			word1: []string{"a", "cb"},
-			word2: []string{"ab", "c"},
-			want:  false,
-		},
-		{
-			word1: []string{"abc", "d", "defg"},
-			word2: []string{"abcddefg"},
-			want:  true,
-		},
-	}
-	for _, tt := range tests {
-		got := arrayStringsAreEqual(tt.word1, tt.word2)
-		if got != tt.want {
-			t.Fatalf("word1: %v, word2: %v, got: %v, want: %v", tt.word1, tt.word2, got, tt.want)
-		}
-	}
-}
diff --git a/problems/check-if-word-can-be-placed-in-crossword/README.md b/problems/check-if-word-can-be-placed-in-crossword/README.md
deleted file mode 100644
index b67375a41..000000000
--- a/problems/check-if-word-can-be-placed-in-crossword/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../grid-game "Grid Game")
-　　　　　　　　　　　　　　　　
-[Next >](../the-score-of-students-solving-math-expression "The Score of Students Solving Math Expression")
-
-## [2018. Check if Word Can Be Placed In Crossword (Medium)](https://leetcode.com/problems/check-if-word-can-be-placed-in-crossword "判断单词是否能放入填字游戏内")
-
-<p>You are given an <code>m x n</code> matrix <code>board</code>, representing the<strong> current </strong>state of a crossword puzzle. The crossword contains lowercase English letters (from solved words), <code>&#39; &#39;</code> to represent any <strong>empty </strong>cells, and <code>&#39;#&#39;</code> to represent any <strong>blocked</strong> cells.</p>
-
-<p>A word can be placed<strong> horizontally</strong> (left to right <strong>or</strong> right to left) or <strong>vertically</strong> (top to bottom <strong>or</strong> bottom to top) in the board if:</p>
-
-<ul>
-	<li>It does not occupy a cell containing the character <code>&#39;#&#39;</code>.</li>
-	<li>The cell each letter is placed in must either be <code>&#39; &#39;</code> (empty) or <strong>match</strong> the letter already on the <code>board</code>.</li>
-	<li>There must not be any empty cells <code>&#39; &#39;</code> or other lowercase letters <strong>directly left or right</strong><strong> </strong>of the word if the word was placed <strong>horizontally</strong>.</li>
-	<li>There must not be any empty cells <code>&#39; &#39;</code> or other lowercase letters <strong>directly above or below</strong> the word if the word was placed <strong>vertically</strong>.</li>
-</ul>
-
-<p>Given a string <code>word</code>, return <code>true</code><em> if </em><code>word</code><em> can be placed in </em><code>board</code><em>, or </em><code>false</code><em> <strong>otherwise</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/04/crossword-ex1-1.png" style="width: 478px; height: 180px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;#&quot;, &quot; &quot;, &quot;#&quot;], [&quot; &quot;, &quot; &quot;, &quot;#&quot;], [&quot;#&quot;, &quot;c&quot;, &quot; &quot;]], word = &quot;abc&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The word &quot;abc&quot; can be placed as shown above (top to bottom).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/04/crossword-ex2-1.png" style="width: 180px; height: 180px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot; &quot;, &quot;#&quot;, &quot;a&quot;], [&quot; &quot;, &quot;#&quot;, &quot;c&quot;], [&quot; &quot;, &quot;#&quot;, &quot;a&quot;]], word = &quot;ac&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to place the word because there will always be a space/letter above or below it.</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/04/crossword-ex3-1.png" style="width: 478px; height: 180px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;#&quot;, &quot; &quot;, &quot;#&quot;], [&quot; &quot;, &quot; &quot;, &quot;#&quot;], [&quot;#&quot;, &quot; &quot;, &quot;c&quot;]], word = &quot;ca&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The word &quot;ca&quot; can be placed as shown above (right to left). 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == board.length</code></li>
-	<li><code>n == board[i].length</code></li>
-	<li><code>1 &lt;= m * n &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>board[i][j]</code> will be <code>&#39; &#39;</code>, <code>&#39;#&#39;</code>, or a lowercase English letter.</li>
-	<li><code>1 &lt;= word.length &lt;= max(m, n)</code></li>
-	<li><code>word</code> will contain only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check all possible placements for the word.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-There is a limited number of places where a word can start.
-</details>
diff --git a/problems/check-if-word-equals-summation-of-two-words/README.md b/problems/check-if-word-equals-summation-of-two-words/README.md
deleted file mode 100644
index 65bbc3074..000000000
--- a/problems/check-if-word-equals-summation-of-two-words/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-xor-sum-of-two-arrays "Minimum XOR Sum of Two Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-value-after-insertion "Maximum Value after Insertion")
-
-## [1880. Check if Word Equals Summation of Two Words (Easy)](https://leetcode.com/problems/check-if-word-equals-summation-of-two-words "检查某单词是否等于两单词之和")
-
-<p>The <strong>letter value</strong> of a letter is its position in the alphabet <strong>starting from 0</strong> (i.e. <code>&#39;a&#39; -&gt; 0</code>, <code>&#39;b&#39; -&gt; 1</code>, <code>&#39;c&#39; -&gt; 2</code>, etc.).</p>
-
-<p>The <strong>numerical value</strong> of some string of lowercase English letters <code>s</code> is the <strong>concatenation</strong> of the <strong>letter values</strong> of each letter in <code>s</code>, which is then <strong>converted</strong> into an integer.</p>
-
-<ul>
-	<li>For example, if <code>s = &quot;acb&quot;</code>, we concatenate each letter&#39;s letter value, resulting in <code>&quot;021&quot;</code>. After converting it, we get <code>21</code>.</li>
-</ul>
-
-<p>You are given three strings <code>firstWord</code>, <code>secondWord</code>, and <code>targetWord</code>, each consisting of lowercase English letters <code>&#39;a&#39;</code> through <code>&#39;j&#39;</code> <strong>inclusive</strong>.</p>
-
-<p>Return <code>true</code> <em>if the <strong>summation</strong> of the <strong>numerical values</strong> of </em><code>firstWord</code><em> and </em><code>secondWord</code><em> equals the <strong>numerical value</strong> of </em><code>targetWord</code><em>, or </em><code>false</code><em> otherwise.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> firstWord = &quot;acb&quot;, secondWord = &quot;cba&quot;, targetWord = &quot;cdb&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-The numerical value of firstWord is &quot;acb&quot; -&gt; &quot;021&quot; -&gt; 21.
-The numerical value of secondWord is &quot;cba&quot; -&gt; &quot;210&quot; -&gt; 210.
-The numerical value of targetWord is &quot;cdb&quot; -&gt; &quot;231&quot; -&gt; 231.
-We return true because 21 + 210 == 231.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> firstWord = &quot;aaa&quot;, secondWord = &quot;a&quot;, targetWord = &quot;aab&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> 
-The numerical value of firstWord is &quot;aaa&quot; -&gt; &quot;000&quot; -&gt; 0.
-The numerical value of secondWord is &quot;a&quot; -&gt; &quot;0&quot; -&gt; 0.
-The numerical value of targetWord is &quot;aab&quot; -&gt; &quot;001&quot; -&gt; 1.
-We return false because 0 + 0 != 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> firstWord = &quot;aaa&quot;, secondWord = &quot;a&quot;, targetWord = &quot;aaaa&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 
-The numerical value of firstWord is &quot;aaa&quot; -&gt; &quot;000&quot; -&gt; 0.
-The numerical value of secondWord is &quot;a&quot; -&gt; &quot;0&quot; -&gt; 0.
-The numerical value of targetWord is &quot;aaaa&quot; -&gt; &quot;0000&quot; -&gt; 0.
-We return true because 0 + 0 == 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= firstWord.length, </code><code>secondWord.length, </code><code>targetWord.length &lt;= 8</code></li>
-	<li><code>firstWord</code>, <code>secondWord</code>, and <code>targetWord</code> consist of lowercase English letters from <code>&#39;a&#39;</code> to <code>&#39;j&#39;</code> <strong>inclusive</strong>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert each character of each word to its numerical value.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check if the numerical values satisfies the condition.
-</details>
diff --git a/problems/check-if-word-is-valid-after-substitutions/README.md b/problems/check-if-word-is-valid-after-substitutions/README.md
deleted file mode 100644
index 25bd6c60f..000000000
--- a/problems/check-if-word-is-valid-after-substitutions/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-common-characters "Find Common Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../max-consecutive-ones-iii "Max Consecutive Ones III")
-
-## [1003. Check If Word Is Valid After Substitutions (Medium)](https://leetcode.com/problems/check-if-word-is-valid-after-substitutions "检查替换后的词是否有效")
-
-<p>Given a string <code>s</code>, determine if it is <strong>valid</strong>.</p>
-
-<p>A string <code>s</code> is <strong>valid</strong> if, starting with an empty string <code>t = &quot;&quot;</code>, you can <strong>transform </strong><code>t</code><strong> into </strong><code>s</code> after performing the following operation <strong>any number of times</strong>:</p>
-
-<ul>
-	<li>Insert string <code>&quot;abc&quot;</code> into any position in <code>t</code>. More formally, <code>t</code> becomes <code>t<sub>left</sub> + &quot;abc&quot; + t<sub>right</sub></code>, where <code>t == t<sub>left</sub> + t<sub>right</sub></code>. Note that <code>t<sub>left</sub></code> and <code>t<sub>right</sub></code> may be <strong>empty</strong>.</li>
-</ul>
-
-<p>Return <code>true</code> <em>if </em><code>s</code><em> is a <strong>valid</strong> string, otherwise, return</em> <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabcbc&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-&quot;&quot; -&gt; &quot;<u>abc</u>&quot; -&gt; &quot;a<u>abc</u>bc&quot;
-Thus, &quot;aabcbc&quot; is valid.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcabcababcc&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-&quot;&quot; -&gt; &quot;<u>abc</u>&quot; -&gt; &quot;abc<u>abc</u>&quot; -&gt; &quot;abcabc<u>abc</u>&quot; -&gt; &quot;abcabcab<u>abc</u>c&quot;
-Thus, &quot;abcabcababcc&quot; is valid.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abccba&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to get &quot;abccba&quot; using the operation.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cababc&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to get &quot;cababc&quot; using the operation.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of letters <code>&#39;a&#39;</code>, <code>&#39;b&#39;</code>, and <code>&#39;c&#39;</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Valid Parentheses](../valid-parentheses) (Easy)
diff --git a/problems/check-if-word-is-valid-after-substitutions/check_if_word_is_valid_after_substitutions.go b/problems/check-if-word-is-valid-after-substitutions/check_if_word_is_valid_after_substitutions.go
deleted file mode 100644
index 8f27a8410..000000000
--- a/problems/check-if-word-is-valid-after-substitutions/check_if_word_is_valid_after_substitutions.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem1003
-
-func isValid(S string) bool {
-	bs := []byte(S)
-	stack := make([]byte, len(S))
-	top := -1
-
-	for _, b := range bs {
-		top++
-		stack[top] = b
-		switch top {
-		case 0:
-			if b != 'a' {
-				return false
-			}
-		case 1:
-		default:
-			if b == 'c' &&
-				stack[top-1] == 'b' &&
-				stack[top-2] == 'a' {
-				top -= 3
-			}
-		}
-	}
-
-	return top == -1
-}
diff --git a/problems/check-whether-two-strings-are-almost-equivalent/README.md b/problems/check-whether-two-strings-are-almost-equivalent/README.md
deleted file mode 100644
index 00b1bcd6e..000000000
--- a/problems/check-whether-two-strings-are-almost-equivalent/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-equal-count-substrings "Number of Equal Count Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../walking-robot-simulation-ii "Walking Robot Simulation II")
-
-## [2068. Check Whether Two Strings are Almost Equivalent (Easy)](https://leetcode.com/problems/check-whether-two-strings-are-almost-equivalent "检查两个字符串是否几乎相等")
-
-<p>Two strings <code>word1</code> and <code>word2</code> are considered <strong>almost equivalent</strong> if the differences between the frequencies of each letter from <code>&#39;a&#39;</code> to <code>&#39;z&#39;</code> between <code>word1</code> and <code>word2</code> is <strong>at most</strong> <code>3</code>.</p>
-
-<p>Given two strings <code>word1</code> and <code>word2</code>, each of length <code>n</code>, return <code>true</code> <em>if </em><code>word1</code> <em>and</em> <code>word2</code> <em>are <strong>almost equivalent</strong>, or</em> <code>false</code> <em>otherwise</em>.</p>
-
-<p>The <strong>frequency</strong> of a letter <code>x</code> is the number of times it occurs in the string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;aaaa&quot;, word2 = &quot;bccb&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There are 4 &#39;a&#39;s in &quot;aaaa&quot; but 0 &#39;a&#39;s in &quot;bccb&quot;.
-The difference is 4, which is more than the allowed 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;abcdeef&quot;, word2 = &quot;abaaacc&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The differences between the frequencies of each letter in word1 and word2 are at most 3:
-- &#39;a&#39; appears 1 time in word1 and 4 times in word2. The difference is 3.
-- &#39;b&#39; appears 1 time in word1 and 1 time in word2. The difference is 0.
-- &#39;c&#39; appears 1 time in word1 and 2 times in word2. The difference is 1.
-- &#39;d&#39; appears 1 time in word1 and 0 times in word2. The difference is 1.
-- &#39;e&#39; appears 2 times in word1 and 0 times in word2. The difference is 2.
-- &#39;f&#39; appears 1 time in word1 and 0 times in word2. The difference is 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;cccddabba&quot;, word2 = &quot;babababab&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The differences between the frequencies of each letter in word1 and word2 are at most 3:
-- &#39;a&#39; appears 2 times in word1 and 4 times in word2. The difference is 2.
-- &#39;b&#39; appears 2 times in word1 and 5 times in word2. The difference is 3.
-- &#39;c&#39; appears 3 times in word1 and 0 times in word2. The difference is 3.
-- &#39;d&#39; appears 2 times in word1 and 0 times in word2. The difference is 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == word1.length == word2.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>word1</code> and <code>word2</code> consist only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What data structure can we use to count the frequency of each character?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Are there edge cases where a character is present in one string but not the other?
-</details>
diff --git a/problems/checking-existence-of-edge-length-limited-paths-ii/README.md b/problems/checking-existence-of-edge-length-limited-paths-ii/README.md
deleted file mode 100644
index c1bdb7548..000000000
--- a/problems/checking-existence-of-edge-length-limited-paths-ii/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-minimum-time-to-finish-all-jobs "Find Minimum Time to Finish All Jobs")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-rectangles-that-can-form-the-largest-square "Number Of Rectangles That Can Form The Largest Square")
-
-## [1724. Checking Existence of Edge Length Limited Paths II (Hard)](https://leetcode.com/problems/checking-existence-of-edge-length-limited-paths-ii "检查边长度限制的路径是否存在 II")
-
-
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Minimum Spanning Tree](../../tag/minimum-spanning-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the minimum spanning tree of the given graph.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Root the tree in an arbitrary node and calculate the maximum weight of the edge from each node to the chosen root.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-To answer a query, find the lca between the two nodes, and find the maximum weight from each of the query nodes to their lca and compare it to the given limit.
-</details>
diff --git a/problems/checking-existence-of-edge-length-limited-paths/README.md b/problems/checking-existence-of-edge-length-limited-paths/README.md
deleted file mode 100644
index cb9115df3..000000000
--- a/problems/checking-existence-of-edge-length-limited-paths/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../jump-game-vi "Jump Game VI")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-distinct-substrings-in-a-string "Number of Distinct Substrings in a String")
-
-## [1697. Checking Existence of Edge Length Limited Paths (Hard)](https://leetcode.com/problems/checking-existence-of-edge-length-limited-paths "检查边长度限制的路径是否存在")
-
-<p>An undirected graph of <code>n</code> nodes is defined by <code>edgeList</code>, where <code>edgeList[i] = [u<sub>i</sub>, v<sub>i</sub>, dis<sub>i</sub>]</code> denotes an edge between nodes <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code> with distance <code>dis<sub>i</sub></code>. Note that there may be <strong>multiple</strong> edges between two nodes.</p>
-
-<p>Given an array <code>queries</code>, where <code>queries[j] = [p<sub>j</sub>, q<sub>j</sub>, limit<sub>j</sub>]</code>, your task is to determine for each <code>queries[j]</code> whether there is a path between <code>p<sub>j</sub></code> and <code>q<sub>j</sub></code><sub> </sub>such that each edge on the path has a distance <strong>strictly less than</strong> <code>limit<sub>j</sub></code> .</p>
-
-<p>Return <em>a <strong>boolean array</strong> </em><code>answer</code><em>, where </em><code>answer.length == queries.length</code> <em>and the </em><code>j<sup>th</sup></code> <em>value of </em><code>answer</code> <em>is </em><code>true</code><em> if there is a path for </em><code>queries[j]</code><em> is </em><code>true</code><em>, and </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/08/h.png" style="width: 267px; height: 262px;" />
-<pre>
-<strong>Input:</strong> n = 3, edgeList = [[0,1,2],[1,2,4],[2,0,8],[1,0,16]], queries = [[0,1,2],[0,2,5]]
-<strong>Output:</strong> [false,true]
-<strong>Explanation:</strong> The above figure shows the given graph. Note that there are two overlapping edges between 0 and 1 with distances 2 and 16.
-For the first query, between 0 and 1 there is no path where each distance is less than 2, thus we return false for this query.
-For the second query, there is a path (0 -&gt; 1 -&gt; 2) of two edges with distances less than 5, thus we return true for this query.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/08/q.png" style="width: 390px; height: 358px;" />
-<pre>
-<strong>Input:</strong> n = 5, edgeList = [[0,1,10],[1,2,5],[2,3,9],[3,4,13]], queries = [[0,4,14],[1,4,13]]
-<strong>Output:</strong> [true,false]
-<strong>Exaplanation:</strong> The above figure shows the given graph.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= edgeList.length, queries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>edgeList[i].length == 3</code></li>
-	<li><code>queries[j].length == 3</code></li>
-	<li><code>0 &lt;= u<sub>i</sub>, v<sub>i</sub>, p<sub>j</sub>, q<sub>j</sub> &lt;= n - 1</code></li>
-	<li><code>u<sub>i</sub> != v<sub>i</sub></code></li>
-	<li><code>p<sub>j</sub> != q<sub>j</sub></code></li>
-	<li><code>1 &lt;= dis<sub>i</sub>, limit<sub>j</sub> &lt;= 10<sup>9</sup></code></li>
-	<li>There may be <strong>multiple</strong> edges between two nodes.</li>
-</ul>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-All the queries are given in advance. Is there a way you can reorder the queries to avoid repeated computations?
-</details>
diff --git a/problems/cherry-pickup-ii/README.md b/problems/cherry-pickup-ii/README.md
deleted file mode 100644
index e44b8c7f0..000000000
--- a/problems/cherry-pickup-ii/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../course-schedule-iv "Course Schedule IV")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-product-of-two-elements-in-an-array "Maximum Product of Two Elements in an Array")
-
-## [1463. Cherry Pickup II (Hard)](https://leetcode.com/problems/cherry-pickup-ii "摘樱桃 II")
-
-<p>You are given a <code>rows x cols</code> matrix <code>grid</code> representing a field of cherries where <code>grid[i][j]</code> represents the number of cherries that you can collect from the <code>(i, j)</code> cell.</p>
-
-<p>You have two robots that can collect cherries for you:</p>
-
-<ul>
-	<li><strong>Robot #1</strong> is located at the <strong>top-left corner</strong> <code>(0, 0)</code>, and</li>
-	<li><strong>Robot #2</strong> is located at the <strong>top-right corner</strong> <code>(0, cols - 1)</code>.</li>
-</ul>
-
-<p>Return <em>the maximum number of cherries collection using both robots by following the rules below</em>:</p>
-
-<ul>
-	<li>From a cell <code>(i, j)</code>, robots can move to cell <code>(i + 1, j - 1)</code>, <code>(i + 1, j)</code>, or <code>(i + 1, j + 1)</code>.</li>
-	<li>When any robot passes through a cell, It picks up all cherries, and the cell becomes an empty cell.</li>
-	<li>When both robots stay in the same cell, only one takes the cherries.</li>
-	<li>Both robots cannot move outside of the grid at any moment.</li>
-	<li>Both robots should reach the bottom row in <code>grid</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/04/29/sample_1_1802.png" style="width: 374px; height: 501px;" />
-<pre>
-<strong>Input:</strong> grid = [[3,1,1],[2,5,1],[1,5,5],[2,1,1]]
-<strong>Output:</strong> 24
-<strong>Explanation:</strong> Path of robot #1 and #2 are described in color green and blue respectively.
-Cherries taken by Robot #1, (3 + 2 + 5 + 2) = 12.
-Cherries taken by Robot #2, (1 + 5 + 5 + 1) = 12.
-Total of cherries: 12 + 12 = 24.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/04/23/sample_2_1802.png" style="width: 500px; height: 452px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,0,0,0,0,0,1],[2,0,0,0,0,3,0],[2,0,9,0,0,0,0],[0,3,0,5,4,0,0],[1,0,2,3,0,0,6]]
-<strong>Output:</strong> 28
-<strong>Explanation:</strong> Path of robot #1 and #2 are described in color green and blue respectively.
-Cherries taken by Robot #1, (1 + 9 + 5 + 2) = 17.
-Cherries taken by Robot #2, (1 + 3 + 4 + 3) = 11.
-Total of cherries: 17 + 11 = 28.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>rows == grid.length</code></li>
-	<li><code>cols == grid[i].length</code></li>
-	<li><code>2 &lt;= rows, cols &lt;= 70</code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynammic programming, define DP[i][j][k]: The maximum cherries that both robots can take  starting on the ith row, and column j and k of Robot 1 and 2 respectively.
-</details>
diff --git a/problems/cherry-pickup/README.md b/problems/cherry-pickup/README.md
deleted file mode 100644
index 07f1b153f..000000000
--- a/problems/cherry-pickup/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-and-earn "Delete and Earn")
-　　　　　　　　　　　　　　　　
-[Next >](../closest-leaf-in-a-binary-tree "Closest Leaf in a Binary Tree")
-
-## [741. Cherry Pickup (Hard)](https://leetcode.com/problems/cherry-pickup "摘樱桃")
-
-<p>You are given an <code>n x n</code> <code>grid</code> representing a field of cherries, each cell is one of three possible integers.</p>
-
-<ul>
-	<li><code>0</code> means the cell is empty, so you can pass through,</li>
-	<li><code>1</code> means the cell contains a cherry that you can pick up and pass through, or</li>
-	<li><code>-1</code> means the cell contains a thorn that blocks your way.</li>
-</ul>
-
-<p>Return <em>the maximum number of cherries you can collect by following the rules below</em>:</p>
-
-<ul>
-	<li>Starting at the position <code>(0, 0)</code> and reaching <code>(n - 1, n - 1)</code> by moving right or down through valid path cells (cells with value <code>0</code> or <code>1</code>).</li>
-	<li>After reaching <code>(n - 1, n - 1)</code>, returning to <code>(0, 0)</code> by moving left or up through valid path cells.</li>
-	<li>When passing through a path cell containing a cherry, you pick it up, and the cell becomes an empty cell <code>0</code>.</li>
-	<li>If there is no valid path between <code>(0, 0)</code> and <code>(n - 1, n - 1)</code>, then no cherries can be collected.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/14/grid.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1,-1],[1,0,-1],[1,1,1]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The player started at (0, 0) and went down, down, right right to reach (2, 2).
-4 cherries were picked up during this single trip, and the matrix becomes [[0,1,-1],[0,0,-1],[0,0,0]].
-Then, the player went left, up, up, left to return home, picking up one more cherry.
-The total number of cherries picked up is 5, and this is the maximum possible.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,-1],[1,-1,1],[-1,1,1]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 50</code></li>
-	<li><code>grid[i][j]</code> is <code>-1</code>, <code>0</code>, or <code>1</code>.</li>
-	<li><code>grid[0][0] != -1</code></li>
-	<li><code>grid[n - 1][n - 1] != -1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Minimum Path Sum](../minimum-path-sum) (Medium)
-  1. [Dungeon Game](../dungeon-game) (Hard)
diff --git a/problems/cherry-pickup/cherry_pickup.go b/problems/cherry-pickup/cherry_pickup.go
deleted file mode 100644
index ee1416c2e..000000000
--- a/problems/cherry-pickup/cherry_pickup.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem741
diff --git a/problems/cherry-pickup/cherry_pickup_test.go b/problems/cherry-pickup/cherry_pickup_test.go
deleted file mode 100644
index ee1416c2e..000000000
--- a/problems/cherry-pickup/cherry_pickup_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem741
diff --git a/problems/choose-numbers-from-two-arrays-in-range/README.md b/problems/choose-numbers-from-two-arrays-in-range/README.md
deleted file mode 100644
index d35ea7619..000000000
--- a/problems/choose-numbers-from-two-arrays-in-range/README.md
+++ /dev/null
@@ -1,34 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-passengers-in-each-bus-i "The Number of Passengers in Each Bus I")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-of-buying-candies-with-discount "Minimum Cost of Buying Candies With Discount")
-
-## [2143. Choose Numbers From Two Arrays in Range (Hard)](https://leetcode.com/problems/choose-numbers-from-two-arrays-in-range "")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you know the possible sums you can get for a range [l, r], how can you use this information to calculate the possible sums you can get for a range [l, r + 1]?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For the range [l, r], if it is possible to choose elements such that the sum of elements you picked from nums1 is x and the sum of elements you picked from nums2 is y, then (x + nums1[r + 1], y) and (x, y + nums2[r + 1]) are possible sums you can get in the range [l, r + 1].
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How can we save the possible sums obtainable at a given index so that we can reuse this information later?
-</details>
diff --git a/problems/cinema-seat-allocation/README.md b/problems/cinema-seat-allocation/README.md
deleted file mode 100644
index 2a9094e0f..000000000
--- a/problems/cinema-seat-allocation/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-distance-value-between-two-arrays "Find the Distance Value Between Two Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-integers-by-the-power-value "Sort Integers by The Power Value")
-
-## [1386. Cinema Seat Allocation (Medium)](https://leetcode.com/problems/cinema-seat-allocation "安排电影院座位")
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/02/14/cinema_seats_1.png" style="width: 400px; height: 149px;" /></p>
-
-<p>A cinema&nbsp;has <code>n</code>&nbsp;rows of seats, numbered from 1 to <code>n</code>&nbsp;and there are ten&nbsp;seats in each row, labelled from 1&nbsp;to 10&nbsp;as shown in the figure above.</p>
-
-<p>Given the array <code>reservedSeats</code> containing the numbers of seats already reserved, for example, <code>reservedSeats[i] = [3,8]</code>&nbsp;means the seat located in row <strong>3</strong> and labelled with <b>8</b>&nbsp;is already reserved.</p>
-
-<p><em>Return the maximum number of four-person groups&nbsp;you can assign on the cinema&nbsp;seats.</em> A four-person group&nbsp;occupies four&nbsp;adjacent seats <strong>in one single row</strong>. Seats across an aisle (such as [3,3]&nbsp;and [3,4]) are not considered to be adjacent, but there is an exceptional case&nbsp;on which an aisle split&nbsp;a four-person group, in that case, the aisle split&nbsp;a four-person group in the middle,&nbsp;which means to have two people on each side.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/02/14/cinema_seats_3.png" style="width: 400px; height: 96px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 3, reservedSeats = [[1,2],[1,3],[1,8],[2,6],[3,1],[3,10]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The figure above shows the optimal allocation for four groups, where seats mark with blue are already reserved and contiguous seats mark with orange are for one group.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, reservedSeats = [[2,1],[1,8],[2,6]]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, reservedSeats = [[4,3],[1,4],[4,6],[1,7]]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10^9</code></li>
-	<li><code>1 &lt;=&nbsp;reservedSeats.length &lt;= min(10*n, 10^4)</code></li>
-	<li><code>reservedSeats[i].length == 2</code></li>
-	<li><code>1&nbsp;&lt;=&nbsp;reservedSeats[i][0] &lt;= n</code></li>
-	<li><code>1 &lt;=&nbsp;reservedSeats[i][1] &lt;= 10</code></li>
-	<li>All <code>reservedSeats[i]</code> are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note you can allocate at most two families in one row.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Greedily check if you can allocate seats for two families, one family or none.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Process only rows that appear in the input, for other rows you can always allocate seats for two families.
-</details>
diff --git a/problems/circle-and-rectangle-overlapping/README.md b/problems/circle-and-rectangle-overlapping/README.md
deleted file mode 100644
index 546cedeb1..000000000
--- a/problems/circle-and-rectangle-overlapping/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-k-palindrome-strings "Construct K Palindrome Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../reducing-dishes "Reducing Dishes")
-
-## [1401. Circle and Rectangle Overlapping (Medium)](https://leetcode.com/problems/circle-and-rectangle-overlapping "圆和矩形是否有重叠")
-
-<p>You are given a circle represented as <code>(radius, xCenter, yCenter)</code> and an axis-aligned rectangle represented as <code>(x1, y1, x2, y2)</code>, where <code>(x1, y1)</code> are the coordinates of the bottom-left corner, and <code>(x2, y2)</code> are the coordinates of the top-right corner of the rectangle.</p>
-
-<p>Return <code>true</code><em> if the circle and rectangle are overlapped otherwise return </em><code>false</code>. In other words, check if there is <strong>any</strong> point <code>(x<sub>i</sub>, y<sub>i</sub>)</code> that belongs to the circle and the rectangle at the same time.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/20/sample_4_1728.png" style="width: 258px; height: 167px;" />
-<pre>
-<strong>Input:</strong> radius = 1, xCenter = 0, yCenter = 0, x1 = 1, y1 = -1, x2 = 3, y2 = 1
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Circle and rectangle share the point (1,0).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> radius = 1, xCenter = 1, yCenter = 1, x1 = 1, y1 = -3, x2 = 2, y2 = -1
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/20/sample_2_1728.png" style="width: 150px; height: 135px;" />
-<pre>
-<strong>Input:</strong> radius = 1, xCenter = 0, yCenter = 0, x1 = -1, y1 = 0, x2 = 0, y2 = 1
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= radius &lt;= 2000</code></li>
-	<li><code>-10<sup>4</sup> &lt;= xCenter, yCenter &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= x1 &lt; x2 &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= y1 &lt; y2 &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Locate the closest point of the square to the circle, you can then find the distance from this point to the center of the circle and check if this is less than or equal to the radius.
-</details>
diff --git a/problems/circular-array-loop/README.md b/problems/circular-array-loop/README.md
deleted file mode 100644
index 48326bf27..000000000
--- a/problems/circular-array-loop/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../132-pattern "132 Pattern")
-　　　　　　　　　　　　　　　　
-[Next >](../poor-pigs "Poor Pigs")
-
-## [457. Circular Array Loop (Medium)](https://leetcode.com/problems/circular-array-loop "环形数组是否存在循环")
-
-<p>You are playing a game involving a <strong>circular</strong> array of non-zero integers <code>nums</code>. Each <code>nums[i]</code> denotes the number of indices forward/backward you must move if you are located at index <code>i</code>:</p>
-
-<ul>
-	<li>If <code>nums[i]</code> is positive, move <code>nums[i]</code> steps <strong>forward</strong>, and</li>
-	<li>If <code>nums[i]</code> is negative, move <code>nums[i]</code> steps <strong>backward</strong>.</li>
-</ul>
-
-<p>Since the array is <strong>circular</strong>, you may assume that moving forward from the last element puts you on the first element, and moving backwards from the first element puts you on the last element.</p>
-
-<p>A <strong>cycle</strong> in the array consists of a sequence of indices <code>seq</code> of length <code>k</code> where:</p>
-
-<ul>
-	<li>Following the movement rules above results in the repeating index sequence <code>seq[0] -&gt; seq[1] -&gt; ... -&gt; seq[k - 1] -&gt; seq[0] -&gt; ...</code></li>
-	<li>Every <code>nums[seq[j]]</code> is either <strong>all positive</strong> or <strong>all negative</strong>.</li>
-	<li><code>k &gt; 1</code></li>
-</ul>
-
-<p>Return <code>true</code><em> if there is a <strong>cycle</strong> in </em><code>nums</code><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,-1,1,2,2]
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-There is a cycle from index 0 -&gt; 2 -&gt; 3 -&gt; 0 -&gt; ...
-The cycle&#39;s length is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-The sequence from index 1 -&gt; 1 -&gt; 1 -&gt; ... is not a cycle because the sequence&#39;s length is 1.
-By definition the sequence&#39;s length must be strictly greater than 1 to be a cycle.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-2,1,-1,-2,-2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-The sequence from index 1 -&gt; 2 -&gt; 1 -&gt; ... is not a cycle because nums[1] is positive, but nums[2] is negative.
-Every nums[seq[j]] must be either all positive or all negative.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5000</code></li>
-	<li><code>-1000 &lt;= nums[i] &lt;= 1000</code></li>
-	<li><code>nums[i] != 0</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you solve it in <code>O(n)</code> time complexity and <code>O(1)</code> extra space complexity?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
diff --git a/problems/circular-array-loop/circular_array_loop.go b/problems/circular-array-loop/circular_array_loop.go
deleted file mode 100644
index dd2d99a0c..000000000
--- a/problems/circular-array-loop/circular_array_loop.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem457
diff --git a/problems/circular-array-loop/circular_array_loop_test.go b/problems/circular-array-loop/circular_array_loop_test.go
deleted file mode 100644
index dd2d99a0c..000000000
--- a/problems/circular-array-loop/circular_array_loop_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem457
diff --git a/problems/circular-permutation-in-binary-representation/README.md b/problems/circular-permutation-in-binary-representation/README.md
deleted file mode 100644
index d3daea1bf..000000000
--- a/problems/circular-permutation-in-binary-representation/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-positive-integer-solution-for-a-given-equation "Find Positive Integer Solution for a Given Equation")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-length-of-a-concatenated-string-with-unique-characters "Maximum Length of a Concatenated String with Unique Characters")
-
-## [1238. Circular Permutation in Binary Representation (Medium)](https://leetcode.com/problems/circular-permutation-in-binary-representation "循环码排列")
-
-<p>Given 2 integers <code>n</code> and <code>start</code>. Your task is return <strong>any</strong> permutation <code>p</code>&nbsp;of <code>(0,1,2.....,2^n -1) </code>such that :</p>
-
-<ul>
-	<li><code>p[0] = start</code></li>
-	<li><code>p[i]</code> and <code>p[i+1]</code>&nbsp;differ by only one bit in their binary representation.</li>
-	<li><code>p[0]</code> and <code>p[2^n -1]</code>&nbsp;must also differ by only one bit in their binary representation.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, start = 3
-<strong>Output:</strong> [3,2,0,1]
-<strong>Explanation:</strong> The binary representation of the permutation is (11,10,00,01). 
-All the adjacent element differ by one bit. Another valid permutation is [3,1,0,2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, start = 2
-<strong>Output:</strong> [2,6,7,5,4,0,1,3]
-<strong>Explanation:</strong> The binary representation of the permutation is (010,110,111,101,100,000,001,011).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 16</code></li>
-	<li><code>0 &lt;= start&nbsp;&lt;&nbsp;2 ^ n</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use gray code to generate a n-bit sequence.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Rotate the sequence such that its first element is start.
-</details>
diff --git a/problems/classes-more-than-5-students/README.md b/problems/classes-more-than-5-students/README.md
deleted file mode 100644
index 4f131c182..000000000
--- a/problems/classes-more-than-5-students/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../big-countries "Big Countries")
-　　　　　　　　　　　　　　　　
-[Next >](../friend-requests-i-overall-acceptance-rate "Friend Requests I: Overall Acceptance Rate")
-
-## [596. Classes More Than 5 Students (Easy)](https://leetcode.com/problems/classes-more-than-5-students "超过5名学生的课")
-
-<p>Table: <code>Courses</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| student     | varchar |
-| class       | varchar |
-+-------------+---------+
-(student, class) is the primary key column for this table.
-Each row of this table indicates the name of a student and the class in which they are enrolled.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to report all the classes that have <strong>at least five students</strong>.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Courses table:
-+---------+----------+
-| student | class    |
-+---------+----------+
-| A       | Math     |
-| B       | English  |
-| C       | Math     |
-| D       | Biology  |
-| E       | Math     |
-| F       | Computer |
-| G       | Math     |
-| H       | Math     |
-| I       | Math     |
-+---------+----------+
-<strong>Output:</strong> 
-+---------+
-| class   |
-+---------+
-| Math    |
-+---------+
-<strong>Explanation:</strong> 
-- Math has 6 students, so we include it.
-- English has 1 student, so we do not include it.
-- Biology has 1 student, so we do not include it.
-- Computer has 1 student, so we do not include it.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/classes-more-than-5-students/classes_more_than_5_students.sql b/problems/classes-more-than-5-students/classes_more_than_5_students.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/classes-more-than-5-students/classes_more_than_5_students.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/classes-more-than-5-students/mysql_schemas.sql b/problems/classes-more-than-5-students/mysql_schemas.sql
deleted file mode 100644
index b063c3153..000000000
--- a/problems/classes-more-than-5-students/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Courses (student varchar(255), class varchar(255));
-Truncate table Courses;
-insert into Courses (student, class) values ('A', 'Math');
-insert into Courses (student, class) values ('B', 'English');
-insert into Courses (student, class) values ('C', 'Math');
-insert into Courses (student, class) values ('D', 'Biology');
-insert into Courses (student, class) values ('E', 'Math');
-insert into Courses (student, class) values ('F', 'Computer');
-insert into Courses (student, class) values ('G', 'Math');
-insert into Courses (student, class) values ('H', 'Math');
-insert into Courses (student, class) values ('I', 'Math');
diff --git a/problems/climbing-stairs/README.md b/problems/climbing-stairs/README.md
deleted file mode 100644
index 5a7ddf992..000000000
--- a/problems/climbing-stairs/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sqrtx "Sqrt(x)")
-　　　　　　　　　　　　　　　　
-[Next >](../simplify-path "Simplify Path")
-
-## [70. Climbing Stairs (Easy)](https://leetcode.com/problems/climbing-stairs "爬楼梯")
-
-<p>You are climbing a staircase. It takes <code>n</code> steps to reach the top.</p>
-
-<p>Each time you can either climb <code>1</code> or <code>2</code> steps. In how many distinct ways can you climb to the top?</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are two ways to climb to the top.
-1. 1 step + 1 step
-2. 2 steps
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> There are three ways to climb to the top.
-1. 1 step + 1 step + 1 step
-2. 1 step + 2 steps
-3. 2 steps + 1 step
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 45</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-
-### Similar Questions
-  1. [Min Cost Climbing Stairs](../min-cost-climbing-stairs) (Easy)
-  1. [Fibonacci Number](../fibonacci-number) (Easy)
-  1. [N-th Tribonacci Number](../n-th-tribonacci-number) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-To reach nth step, what could have been your previous steps? (Think about the step sizes)
-</details>
diff --git a/problems/climbing-stairs/climbing_stairs.go b/problems/climbing-stairs/climbing_stairs.go
deleted file mode 100644
index 5934d0c4a..000000000
--- a/problems/climbing-stairs/climbing_stairs.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem70
-
-func climbStairs(n int) int {
-	if n == 1 {
-		return 1
-	}
-	first, second := 1, 2
-	for i := 3; i <= n; i++ {
-		first, second = second, first+second
-	}
-	return second
-}
diff --git a/problems/climbing-stairs/climbing_stairs_test.go b/problems/climbing-stairs/climbing_stairs_test.go
deleted file mode 100644
index 9f9aba81b..000000000
--- a/problems/climbing-stairs/climbing_stairs_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem70
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestClimbStairs(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   1,
-			want: 1,
-		},
-		{
-			in:   2,
-			want: 2,
-		},
-		{
-			in:   3,
-			want: 3,
-		},
-	}
-	for _, tt := range tests {
-		got := climbStairs(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/clone-binary-tree-with-random-pointer/README.md b/problems/clone-binary-tree-with-random-pointer/README.md
deleted file mode 100644
index e50978b09..000000000
--- a/problems/clone-binary-tree-with-random-pointer/README.md
+++ /dev/null
@@ -1,37 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../group-sold-products-by-the-date "Group Sold Products By The Date")
-　　　　　　　　　　　　　　　　
-[Next >](../xor-operation-in-an-array "XOR Operation in an Array")
-
-## [1485. Clone Binary Tree With Random Pointer (Medium)](https://leetcode.com/problems/clone-binary-tree-with-random-pointer "克隆含随机指针的二叉树")
-
-
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Clone Graph](../clone-graph) (Medium)
-  1. [Copy List with Random Pointer](../copy-list-with-random-pointer) (Medium)
-  1. [Clone N-ary Tree](../clone-n-ary-tree) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Traverse the tree, keep a hashtable with you and create a nodecopy for each node in the tree.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Start traversing the original tree again and connect the left, right and random pointers in the cloned tree the same way as the original tree with the help of the hashtable.
-</details>
diff --git a/problems/clone-graph/README.md b/problems/clone-graph/README.md
deleted file mode 100644
index 4c7683c89..000000000
--- a/problems/clone-graph/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-partitioning-ii "Palindrome Partitioning II")
-　　　　　　　　　　　　　　　　
-[Next >](../gas-station "Gas Station")
-
-## [133. Clone Graph (Medium)](https://leetcode.com/problems/clone-graph "克隆图")
-
-<p>Given a reference of a node in a <strong><a href="https://en.wikipedia.org/wiki/Connectivity_(graph_theory)#Connected_graph" target="_blank">connected</a></strong> undirected graph.</p>
-
-<p>Return a <a href="https://en.wikipedia.org/wiki/Object_copying#Deep_copy" target="_blank"><strong>deep copy</strong></a> (clone) of the graph.</p>
-
-<p>Each node in the graph contains a value (<code>int</code>) and a list (<code>List[Node]</code>) of its neighbors.</p>
-
-<pre>
-class Node {
-    public int val;
-    public List&lt;Node&gt; neighbors;
-}
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Test case format:</strong></p>
-
-<p>For simplicity, each node&#39;s value is the same as the node&#39;s index (1-indexed). For example, the first node with <code>val == 1</code>, the second node with <code>val == 2</code>, and so on. The graph is represented in the test case using an adjacency list.</p>
-
-<p><b>An adjacency list</b> is a collection of unordered <b>lists</b> used to represent a finite graph. Each list describes the set of neighbors of a node in the graph.</p>
-
-<p>The given node will always be the first node with <code>val = 1</code>. You must return the <strong>copy of the given node</strong> as a reference to the cloned graph.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/04/133_clone_graph_question.png" style="width: 500px; height: 550px;" />
-<pre>
-<strong>Input:</strong> adjList = [[2,4],[1,3],[2,4],[1,3]]
-<strong>Output:</strong> [[2,4],[1,3],[2,4],[1,3]]
-<strong>Explanation:</strong> There are 4 nodes in the graph.
-1st node (val = 1)&#39;s neighbors are 2nd node (val = 2) and 4th node (val = 4).
-2nd node (val = 2)&#39;s neighbors are 1st node (val = 1) and 3rd node (val = 3).
-3rd node (val = 3)&#39;s neighbors are 2nd node (val = 2) and 4th node (val = 4).
-4th node (val = 4)&#39;s neighbors are 1st node (val = 1) and 3rd node (val = 3).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/07/graph.png" style="width: 163px; height: 148px;" />
-<pre>
-<strong>Input:</strong> adjList = [[]]
-<strong>Output:</strong> [[]]
-<strong>Explanation:</strong> Note that the input contains one empty list. The graph consists of only one node with val = 1 and it does not have any neighbors.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> adjList = []
-<strong>Output:</strong> []
-<strong>Explanation:</strong> This an empty graph, it does not have any nodes.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/07/graph-1.png" style="width: 272px; height: 133px;" />
-<pre>
-<strong>Input:</strong> adjList = [[2],[1]]
-<strong>Output:</strong> [[2],[1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the graph is in the range <code>[0, 100]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
-	<li><code>Node.val</code> is unique for each node.</li>
-	<li>There are no repeated edges and no self-loops in the graph.</li>
-	<li>The Graph is connected and all nodes can be visited starting from the given node.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [Copy List with Random Pointer](../copy-list-with-random-pointer) (Medium)
diff --git a/problems/clone-graph/clone_graph.go b/problems/clone-graph/clone_graph.go
deleted file mode 100644
index 930f0f2fe..000000000
--- a/problems/clone-graph/clone_graph.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem133
diff --git a/problems/clone-graph/clone_graph.py b/problems/clone-graph/clone_graph.py
deleted file mode 100755
index 302ce22d5..000000000
--- a/problems/clone-graph/clone_graph.py
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a Node.
-class Node:
-    def __init__(self, val, neighbors):
-        self.val = val
-        self.neighbors = neighbors
-"""
-class Solution:
-    def cloneGraph(self, node: 'Node') -> 'Node':
-        
\ No newline at end of file
diff --git a/problems/clone-graph/clone_graph_test.go b/problems/clone-graph/clone_graph_test.go
deleted file mode 100644
index 930f0f2fe..000000000
--- a/problems/clone-graph/clone_graph_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem133
diff --git a/problems/clone-n-ary-tree/README.md b/problems/clone-n-ary-tree/README.md
deleted file mode 100644
index d1d37b8bd..000000000
--- a/problems/clone-n-ary-tree/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree "Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../average-salary-excluding-the-minimum-and-maximum-salary "Average Salary Excluding the Minimum and Maximum Salary")
-
-## [1490. Clone N-ary Tree (Medium)](https://leetcode.com/problems/clone-n-ary-tree "克隆 N 叉树")
-
-
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Clone Graph](../clone-graph) (Medium)
-  1. [Copy List with Random Pointer](../copy-list-with-random-pointer) (Medium)
-  1. [Clone Binary Tree With Random Pointer](../clone-binary-tree-with-random-pointer) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Traverse the tree, keep a hashtable with you and create a clone node for each node in the tree.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Start traversing the original tree again and connect each child pointer in the cloned tree the same way as the original tree with the help of the hashtable.
-</details>
diff --git a/problems/closest-binary-search-tree-value-ii/README.md b/problems/closest-binary-search-tree-value-ii/README.md
deleted file mode 100644
index 441168f84..000000000
--- a/problems/closest-binary-search-tree-value-ii/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../encode-and-decode-strings "Encode and Decode Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../integer-to-english-words "Integer to English Words")
-
-## [272. Closest Binary Search Tree Value II (Hard)](https://leetcode.com/problems/closest-binary-search-tree-value-ii "最接近的二叉搜索树值 II")
-
-<p>Given a non-empty binary search tree and a target value, find <i>k</i> values in the BST that are closest to the target.</p>
-
-<p><b>Note:</b></p>
-
-<ul>
-	<li>Given target value is a floating point.</li>
-	<li>You may assume <i>k</i> is always valid, that is: <i>k</i> &le; total nodes.</li>
-	<li>You are guaranteed to have only one unique set of <i>k</i> values in the BST that are closest to the target.</li>
-</ul>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [4,2,5,1,3], target = 3.714286, and <em>k</em> = 2
-
-    4
-   / \
-  2   5
- / \
-1   3
-
-<strong>Output:</strong> [4,3]</pre>
-
-<p><b>Follow up:</b><br />
-Assume that the BST is balanced, could you solve it in less than <i>O</i>(<i>n</i>) runtime (where <i>n</i> = total nodes)?</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Inorder Traversal](../binary-tree-inorder-traversal) (Easy)
-  1. [Closest Binary Search Tree Value](../closest-binary-search-tree-value) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider implement these two helper functions:
-<ol type="i"><li><code>getPredecessor(N)</code>, which returns the next smaller node to N.</li>
-<li><code>getSuccessor(N)</code>, which returns the next larger node to N.</li>
-</ol>
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to assume that each node has a parent pointer, it makes the problem much easier.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Without parent pointer we just need to keep track of the path from the root to the current node using a stack.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-You would need two stacks to track the path in finding predecessor and successor node separately.
-</details>
diff --git a/problems/closest-binary-search-tree-value-ii/closest_binary_search_tree_value_ii.go b/problems/closest-binary-search-tree-value-ii/closest_binary_search_tree_value_ii.go
deleted file mode 100644
index 15c7eb7c1..000000000
--- a/problems/closest-binary-search-tree-value-ii/closest_binary_search_tree_value_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem272
diff --git a/problems/closest-binary-search-tree-value-ii/closest_binary_search_tree_value_ii_test.go b/problems/closest-binary-search-tree-value-ii/closest_binary_search_tree_value_ii_test.go
deleted file mode 100644
index 15c7eb7c1..000000000
--- a/problems/closest-binary-search-tree-value-ii/closest_binary_search_tree_value_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem272
diff --git a/problems/closest-binary-search-tree-value/README.md b/problems/closest-binary-search-tree-value/README.md
deleted file mode 100644
index 6178001ff..000000000
--- a/problems/closest-binary-search-tree-value/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../alien-dictionary "Alien Dictionary")
-　　　　　　　　　　　　　　　　
-[Next >](../encode-and-decode-strings "Encode and Decode Strings")
-
-## [270. Closest Binary Search Tree Value (Easy)](https://leetcode.com/problems/closest-binary-search-tree-value "最接近的二叉搜索树值")
-
-<p>Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target.</p>
-
-<p><b>Note:</b></p>
-
-<ul>
-	<li>Given target value is a floating point.</li>
-	<li>You are guaranteed to have only one unique value in the BST that is closest to the target.</li>
-</ul>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [4,2,5,1,3], target = 3.714286
-
-    4
-   / \
-  2   5
- / \
-1   3
-
-<strong>Output:</strong> 4
-</pre>
-
-### Related Topics
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Count Complete Tree Nodes](../count-complete-tree-nodes) (Medium)
-  1. [Closest Binary Search Tree Value II](../closest-binary-search-tree-value-ii) (Hard)
-  1. [Search in a Binary Search Tree](../search-in-a-binary-search-tree) (Easy)
diff --git a/problems/closest-binary-search-tree-value/closest_binary_search_tree_value.go b/problems/closest-binary-search-tree-value/closest_binary_search_tree_value.go
deleted file mode 100644
index 349405545..000000000
--- a/problems/closest-binary-search-tree-value/closest_binary_search_tree_value.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem270
diff --git a/problems/closest-binary-search-tree-value/closest_binary_search_tree_value_test.go b/problems/closest-binary-search-tree-value/closest_binary_search_tree_value_test.go
deleted file mode 100644
index 349405545..000000000
--- a/problems/closest-binary-search-tree-value/closest_binary_search_tree_value_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem270
diff --git a/problems/closest-dessert-cost/README.md b/problems/closest-dessert-cost/README.md
deleted file mode 100644
index 876fe6d2c..000000000
--- a/problems/closest-dessert-cost/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-items-matching-a-rule "Count Items Matching a Rule")
-　　　　　　　　　　　　　　　　
-[Next >](../equal-sum-arrays-with-minimum-number-of-operations "Equal Sum Arrays With Minimum Number of Operations")
-
-## [1774. Closest Dessert Cost (Medium)](https://leetcode.com/problems/closest-dessert-cost "最接近目标价格的甜点成本")
-
-<p>You would like to make dessert and are preparing to buy the ingredients. You have <code>n</code> ice cream base flavors and <code>m</code> types of toppings to choose from. You must follow these rules when making your dessert:</p>
-
-<ul>
-	<li>There must be <strong>exactly one</strong> ice cream base.</li>
-	<li>You can add <strong>one or more</strong> types of topping or have no toppings at all.</li>
-	<li>There are <strong>at most two</strong> of <strong>each type</strong> of topping.</li>
-</ul>
-
-<p>You are given three inputs:</p>
-
-<ul>
-	<li><code>baseCosts</code>, an integer array of length <code>n</code>, where each <code>baseCosts[i]</code> represents the price of the <code>i<sup>th</sup></code> ice cream base flavor.</li>
-	<li><code>toppingCosts</code>, an integer array of length <code>m</code>, where each <code>toppingCosts[i]</code> is the price of <strong>one</strong> of the <code>i<sup>th</sup></code> topping.</li>
-	<li><code>target</code>, an integer representing your target price for dessert.</li>
-</ul>
-
-<p>You want to make a dessert with a total cost as close to <code>target</code> as possible.</p>
-
-<p>Return <em>the closest possible cost of the dessert to </em><code>target</code>. If there are multiple, return <em>the <strong>lower</strong> one.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> baseCosts = [1,7], toppingCosts = [3,4], target = 10
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> Consider the following combination (all 0-indexed):
-- Choose base 1: cost 7
-- Take 1 of topping 0: cost 1 x 3 = 3
-- Take 0 of topping 1: cost 0 x 4 = 0
-Total: 7 + 3 + 0 = 10.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> baseCosts = [2,3], toppingCosts = [4,5,100], target = 18
-<strong>Output:</strong> 17
-<strong>Explanation:</strong> Consider the following combination (all 0-indexed):
-- Choose base 1: cost 3
-- Take 1 of topping 0: cost 1 x 4 = 4
-- Take 2 of topping 1: cost 2 x 5 = 10
-- Take 0 of topping 2: cost 0 x 100 = 0
-Total: 3 + 4 + 10 + 0 = 17. You cannot make a dessert with a total cost of 18.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> baseCosts = [3,10], toppingCosts = [2,5], target = 9
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> It is possible to make desserts with cost 8 and 10. Return 8 as it is the lower cost.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == baseCosts.length</code></li>
-	<li><code>m == toppingCosts.length</code></li>
-	<li><code>1 &lt;= n, m &lt;= 10</code></li>
-	<li><code>1 &lt;= baseCosts[i], toppingCosts[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= target &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-As the constraints are not large, you can brute force and enumerate all the possibilities.
-</details>
diff --git a/problems/closest-divisors/README.md b/problems/closest-divisors/README.md
deleted file mode 100644
index 85e11e737..000000000
--- a/problems/closest-divisors/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../validate-binary-tree-nodes "Validate Binary Tree Nodes")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-multiple-of-three "Largest Multiple of Three")
-
-## [1362. Closest Divisors (Medium)](https://leetcode.com/problems/closest-divisors "最接近的因数")
-
-<p>Given an integer <code>num</code>, find the closest two integers in absolute difference whose product equals&nbsp;<code>num + 1</code>&nbsp;or <code>num + 2</code>.</p>
-
-<p>Return the two integers in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 8
-<strong>Output:</strong> [3,3]
-<strong>Explanation:</strong> For num + 1 = 9, the closest divisors are 3 &amp; 3, for num + 2 = 10, the closest divisors are 2 &amp; 5, hence 3 &amp; 3 is chosen.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 123
-<strong>Output:</strong> [5,25]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 999
-<strong>Output:</strong> [40,25]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num &lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the divisors of n+1 and n+2.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To find the divisors of a number, you only need to iterate to the square root of that number.
-</details>
diff --git a/problems/closest-leaf-in-a-binary-tree/README.md b/problems/closest-leaf-in-a-binary-tree/README.md
deleted file mode 100644
index 417cfb5a6..000000000
--- a/problems/closest-leaf-in-a-binary-tree/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cherry-pickup "Cherry Pickup")
-　　　　　　　　　　　　　　　　
-[Next >](../network-delay-time "Network Delay Time")
-
-## [742. Closest Leaf in a Binary Tree (Medium)](https://leetcode.com/problems/closest-leaf-in-a-binary-tree "二叉树最近的叶节点")
-
-<p>Given a binary tree <b>where every node has a unique value</b>, and a target key <code>k</code>, find the value of the nearest leaf node to target <code>k</code> in the tree.
-</p><p>
-Here, <i>nearest</i> to a leaf means the least number of edges travelled on the binary tree to reach any leaf of the tree.  Also, a node is called a <i>leaf</i> if it has no children.
-</p><p>
-In the following examples, the input tree is represented in flattened form row by row.
-The actual <code>root</code> tree given will be a TreeNode object.
-</p><p>
-<b>Example 1:</b>
-<pre>
-<b>Input:</b>
-root = [1, 3, 2], k = 1
-Diagram of binary tree:
-          1
-         / \
-        3   2
-
-<b>Output:</b> 2 (or 3)
-
-<b>Explanation:</b> Either 2 or 3 is the nearest leaf node to the target of 1.
-</pre>
-</p><p>
-<b>Example 2:</b>
-<pre>
-<b>Input:</b>
-root = [1], k = 1
-<b>Output:</b> 1
-
-<b>Explanation:</b> The nearest leaf node is the root node itself.
-</pre>
-</p>
-
-<p>
-<b>Example 3:</b>
-<pre>
-<b>Input:</b>
-root = [1,2,3,4,null,null,null,5,null,6], k = 2
-Diagram of binary tree:
-             1
-            / \
-           2   3
-          /
-         4
-        /
-       5
-      /
-     6
-
-<b>Output:</b> 3
-<b>Explanation:</b> The leaf node with value 3 (and not the leaf node with value 6) is nearest to the node with value 2.
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li><code>root</code> represents a binary tree with at least <code>1</code> node and at most <code>1000</code> nodes.</li>
-<li>Every node has a unique <code>node.val</code> in range <code>[1, 1000]</code>.</li>
-<li>There exists some node in the given binary tree for which <code>node.val == k</code>.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert the tree to a general graph, and do a breadth-first search.  Alternatively, find the closest leaf for every node on the path from root to target.
-</details>
diff --git a/problems/closest-leaf-in-a-binary-tree/closest_leaf_in_a_binary_tree.go b/problems/closest-leaf-in-a-binary-tree/closest_leaf_in_a_binary_tree.go
deleted file mode 100644
index 3fa1fe338..000000000
--- a/problems/closest-leaf-in-a-binary-tree/closest_leaf_in_a_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem742
diff --git a/problems/closest-leaf-in-a-binary-tree/closest_leaf_in_a_binary_tree_test.go b/problems/closest-leaf-in-a-binary-tree/closest_leaf_in_a_binary_tree_test.go
deleted file mode 100644
index 3fa1fe338..000000000
--- a/problems/closest-leaf-in-a-binary-tree/closest_leaf_in_a_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem742
diff --git a/problems/closest-room/README.md b/problems/closest-room/README.md
deleted file mode 100644
index 6b25587c4..000000000
--- a/problems/closest-room/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-element-after-decreasing-and-rearranging "Maximum Element After Decreasing and Rearranging")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-distance-to-the-target-element "Minimum Distance to the Target Element")
-
-## [1847. Closest Room (Hard)](https://leetcode.com/problems/closest-room "最近的房间")
-
-<p>There is a hotel with <code>n</code> rooms. The rooms are represented by a 2D integer array <code>rooms</code> where <code>rooms[i] = [roomId<sub>i</sub>, size<sub>i</sub>]</code> denotes that there is a room with room number <code>roomId<sub>i</sub></code> and size equal to <code>size<sub>i</sub></code>. Each <code>roomId<sub>i</sub></code> is guaranteed to be <strong>unique</strong>.</p>
-
-<p>You are also given <code>k</code> queries in a 2D array <code>queries</code> where <code>queries[j] = [preferred<sub>j</sub>, minSize<sub>j</sub>]</code>. The answer to the <code>j<sup>th</sup></code> query is the room number <code>id</code> of a room such that:</p>
-
-<ul>
-	<li>The room has a size of <strong>at least</strong> <code>minSize<sub>j</sub></code>, and</li>
-	<li><code>abs(id - preferred<sub>j</sub>)</code> is <strong>minimized</strong>, where <code>abs(x)</code> is the absolute value of <code>x</code>.</li>
-</ul>
-
-<p>If there is a <strong>tie</strong> in the absolute difference, then use the room with the <strong>smallest</strong> such <code>id</code>. If there is <strong>no such room</strong>, the answer is <code>-1</code>.</p>
-
-<p>Return <em>an array </em><code>answer</code><em> of length </em><code>k</code><em> where </em><code>answer[j]</code><em> contains the answer to the </em><code>j<sup>th</sup></code><em> query</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rooms = [[2,2],[1,2],[3,2]], queries = [[3,1],[3,3],[5,2]]
-<strong>Output:</strong> [3,-1,3]
-<strong>Explanation: </strong>The answers to the queries are as follows:
-Query = [3,1]: Room number 3 is the closest as abs(3 - 3) = 0, and its size of 2 is at least 1. The answer is 3.
-Query = [3,3]: There are no rooms with a size of at least 3, so the answer is -1.
-Query = [5,2]: Room number 3 is the closest as abs(3 - 5) = 2, and its size of 2 is at least 2. The answer is 3.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rooms = [[1,4],[2,3],[3,5],[4,1],[5,2]], queries = [[2,3],[2,4],[2,5]]
-<strong>Output:</strong> [2,1,3]
-<strong>Explanation: </strong>The answers to the queries are as follows:
-Query = [2,3]: Room number 2 is the closest as abs(2 - 2) = 0, and its size of 3 is at least 3. The answer is 2.
-Query = [2,4]: Room numbers 1 and 3 both have sizes of at least 4. The answer is 1 since it is smaller.
-Query = [2,5]: Room number 3 is the only room with a size of at least 5. The answer is 3.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == rooms.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>k == queries.length</code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= roomId<sub>i</sub>, preferred<sub>j</sub> &lt;= 10<sup>7</sup></code></li>
-	<li><code>1 &lt;= size<sub>i</sub>, minSize<sub>j</sub> &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is there a way to sort the queries so it's easier to search the closest room larger than the size?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use binary search to speed up the search time.
-</details>
diff --git a/problems/closest-subsequence-sum/README.md b/problems/closest-subsequence-sum/README.md
deleted file mode 100644
index 1f41fe465..000000000
--- a/problems/closest-subsequence-sum/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-merge-of-two-strings "Largest Merge Of Two Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../design-most-recently-used-queue "Design Most Recently Used Queue")
-
-## [1755. Closest Subsequence Sum (Hard)](https://leetcode.com/problems/closest-subsequence-sum "最接近目标值的子序列和")
-
-<p>You are given an integer array <code>nums</code> and an integer <code>goal</code>.</p>
-
-<p>You want to choose a subsequence of <code>nums</code> such that the sum of its elements is the closest possible to <code>goal</code>. That is, if the sum of the subsequence&#39;s elements is <code>sum</code>, then you want to <strong>minimize the absolute difference</strong> <code>abs(sum - goal)</code>.</p>
-
-<p>Return <em>the <strong>minimum</strong> possible value of</em> <code>abs(sum - goal)</code>.</p>
-
-<p>Note that a subsequence of an array is an array formed by removing some elements <strong>(possibly all or none)</strong> of the original array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,-7,3,5], goal = 6
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Choose the whole array as a subsequence, with a sum of 6.
-This is equal to the goal, so the absolute difference is 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,-9,15,-2], goal = -5
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Choose the subsequence [7,-9,-2], with a sum of -4.
-The absolute difference is abs(-4 - (-5)) = abs(1) = 1, which is the minimum.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3], goal = -7
-<strong>Output:</strong> 7
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 40</code></li>
-	<li><code>-10<sup>7</sup> &lt;= nums[i] &lt;= 10<sup>7</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= goal &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The naive solution is to check all possible subsequences. This works in O(2^n).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Divide the array into two parts of nearly is equal size.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Consider all subsets of one part and make a list of all possible subset sums and sort this list.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Consider all subsets of the other part, and for each one, let its sum = x, do binary search to get the nearest possible value to goal - x in the first part.
-</details>
diff --git a/problems/clumsy-factorial/README.md b/problems/clumsy-factorial/README.md
deleted file mode 100644
index b6ca2e085..000000000
--- a/problems/clumsy-factorial/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximize-sum-of-array-after-k-negations "Maximize Sum Of Array After K Negations")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-domino-rotations-for-equal-row "Minimum Domino Rotations For Equal Row")
-
-## [1006. Clumsy Factorial (Medium)](https://leetcode.com/problems/clumsy-factorial "笨阶乘")
-
-<p>The <strong>factorial</strong> of a positive integer <code>n</code> is the product of all positive integers less than or equal to <code>n</code>.</p>
-
-<ul>
-	<li>For example, <code>factorial(10) = 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1</code>.</li>
-</ul>
-
-<p>We make a <strong>clumsy factorial</strong> using the integers in decreasing order by swapping out the multiply operations for a fixed rotation of operations with multiply <code>&#39;*&#39;</code>, divide <code>&#39;/&#39;</code>, add <code>&#39;+&#39;</code>, and subtract <code>&#39;-&#39;</code> in this order.</p>
-
-<ul>
-	<li>For example, <code>clumsy(10) = 10 * 9 / 8 + 7 - 6 * 5 / 4 + 3 - 2 * 1</code>.</li>
-</ul>
-
-<p>However, these operations are still applied using the usual order of operations of arithmetic. We do all multiplication and division steps before any addition or subtraction steps, and multiplication and division steps are processed left to right.</p>
-
-<p>Additionally, the division that we use is floor division such that <code>10 * 9 / 8 = 90 / 8 = 11</code>.</p>
-
-<p>Given an integer <code>n</code>, return <em>the clumsy factorial of </em><code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> 7 = 4 * 3 / 2 + 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> 12 = 10 * 9 / 8 + 7 - 6 * 5 / 4 + 3 - 2 * 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/clumsy-factorial/clumsy_factorial.go b/problems/clumsy-factorial/clumsy_factorial.go
deleted file mode 100644
index d0b0ddf88..000000000
--- a/problems/clumsy-factorial/clumsy_factorial.go
+++ /dev/null
@@ -1,22 +0,0 @@
-package problem1006
-
-var answers = []int{0, 1, 2, 6, 7}
-
-func clumsy(N int) int {
-	if N <= 4 {
-		return answers[N]
-	}
-	a := N*(N-1)/(N-2) + (N - 3)
-	b := (N - 4) * max(1, N-5) / max(1, N-6)
-	return a - 2*b + clumsy(N-4)
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
-
-// go to look O(1) solution
-// https://leetcode.com/problems/clumsy-factorial/discuss/252279/You-never-think-of-this-amazing-O(1)-solution
diff --git a/problems/coin-change-2/README.md b/problems/coin-change-2/README.md
deleted file mode 100644
index 3a3054672..000000000
--- a/problems/coin-change-2/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../super-washing-machines "Super Washing Machines")
-　　　　　　　　　　　　　　　　
-[Next >](../random-flip-matrix "Random Flip Matrix")
-
-## [518. Coin Change 2 (Medium)](https://leetcode.com/problems/coin-change-2 "零钱兑换 II")
-
-<p>You are given an integer array <code>coins</code> representing coins of different denominations and an integer <code>amount</code> representing a total amount of money.</p>
-
-<p>Return <em>the number of combinations that make up that amount</em>. If that amount of money cannot be made up by any combination of the coins, return <code>0</code>.</p>
-
-<p>You may assume that you have an infinite number of each kind of coin.</p>
-
-<p>The answer is <strong>guaranteed</strong> to fit into a signed <strong>32-bit</strong> integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> amount = 5, coins = [1,2,5]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> there are four ways to make up the amount:
-5=5
-5=2+2+1
-5=2+1+1+1
-5=1+1+1+1+1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> amount = 3, coins = [2]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> the amount of 3 cannot be made up just with coins of 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> amount = 10, coins = [10]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= coins.length &lt;= 300</code></li>
-	<li><code>1 &lt;= coins[i] &lt;= 5000</code></li>
-	<li>All the values of <code>coins</code> are <strong>unique</strong>.</li>
-	<li><code>0 &lt;= amount &lt;= 5000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/coin-change-2/coin_change_2.go b/problems/coin-change-2/coin_change_2.go
deleted file mode 100644
index 4e53237e0..000000000
--- a/problems/coin-change-2/coin_change_2.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem518
diff --git a/problems/coin-change-2/coin_change_2_test.go b/problems/coin-change-2/coin_change_2_test.go
deleted file mode 100644
index 4e53237e0..000000000
--- a/problems/coin-change-2/coin_change_2_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem518
diff --git a/problems/coin-change/README.md b/problems/coin-change/README.md
deleted file mode 100644
index f04cc4b62..000000000
--- a/problems/coin-change/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../create-maximum-number "Create Maximum Number")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-connected-components-in-an-undirected-graph "Number of Connected Components in an Undirected Graph")
-
-## [322. Coin Change (Medium)](https://leetcode.com/problems/coin-change "零钱兑换")
-
-<p>You are given an integer array <code>coins</code> representing coins of different denominations and an integer <code>amount</code> representing a total amount of money.</p>
-
-<p>Return <em>the fewest number of coins that you need to make up that amount</em>. If that amount of money cannot be made up by any combination of the coins, return <code>-1</code>.</p>
-
-<p>You may assume that you have an infinite number of each kind of coin.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> coins = [1,2,5], amount = 11
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 11 = 5 + 5 + 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> coins = [2], amount = 3
-<strong>Output:</strong> -1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> coins = [1], amount = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> coins = [1], amount = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> coins = [1], amount = 2
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= coins.length &lt;= 12</code></li>
-	<li><code>1 &lt;= coins[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>0 &lt;= amount &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Minimum Cost For Tickets](../minimum-cost-for-tickets) (Medium)
diff --git a/problems/coin-change/coin_change.go b/problems/coin-change/coin_change.go
deleted file mode 100644
index 4e483dbdf..000000000
--- a/problems/coin-change/coin_change.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem322
diff --git a/problems/coin-change/coin_change_test.go b/problems/coin-change/coin_change_test.go
deleted file mode 100644
index 4e483dbdf..000000000
--- a/problems/coin-change/coin_change_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem322
diff --git a/problems/coin-path/README.md b/problems/coin-path/README.md
deleted file mode 100644
index 35ef5334b..000000000
--- a/problems/coin-path/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../print-binary-tree "Print Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../robot-return-to-origin "Robot Return to Origin")
-
-## [656. Coin Path (Hard)](https://leetcode.com/problems/coin-path "金币路径")
-
-<p>Given an array <code>A</code> (index starts at <code>1</code>) consisting of N integers: A<sub>1</sub>, A<sub>2</sub>, ..., A<sub>N</sub>&nbsp;and an integer <code>B</code>. The integer <code>B</code> denotes that from any place (suppose the index is <code>i</code>) in the array <code>A</code>, you can jump to any one of the place in the array <code>A</code> indexed <code>i+1</code>, <code>i+2</code>, &hellip;, <code>i+B</code> if this place can be jumped to. Also, if you step on the index <code>i</code>, you have to pay A<sub>i</sub>&nbsp;coins. If A<sub>i</sub>&nbsp;is -1, it means you can&rsquo;t jump to the place indexed <code>i</code> in the array.</p>
-
-<p>Now, you start from the place indexed <code>1</code> in the array <code>A</code>, and your aim is to reach the place indexed <code>N</code> using the minimum coins. You need to return the path of indexes (starting from 1 to N) in the array you should take to get to the place indexed <code>N</code> using minimum coins.</p>
-
-<p>If there are multiple paths with the same cost, return the lexicographically smallest such path.</p>
-
-<p>If it&#39;s not possible to reach the place indexed N then you need to return an empty array.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<b>Input:</b> [1,2,4,-1,2], 2
-<b>Output:</b> [1,3,5]
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<b>Input:</b> [1,2,4,-1,2], 1
-<b>Output:</b> []
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>Path Pa<sub>1</sub>, Pa<sub>2</sub>, ..., Pa<sub>n</sub>&nbsp;is lexicographically smaller than Pb<sub>1</sub>, Pb<sub>2</sub>, ..., Pb<sub>m</sub>, if and only if at the first <code>i</code> where Pa<sub>i</sub>&nbsp;and Pb<sub>i</sub>&nbsp;differ, Pa<sub>i</sub>&nbsp;&lt; Pb<sub>i</sub>; when no such&nbsp;<code>i</code>&nbsp;exists, then&nbsp;<code>n</code> &lt; <code>m</code>.</li>
-	<li>A<sub>1</sub> &gt;= 0. A<sub>2</sub>, ..., A<sub>N</sub> (if exist) will in the range of [-1, 100].</li>
-	<li>Length of A is in the range of [1, 1000].</li>
-	<li>B is in the range of [1, 100].</li>
-</ol>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [House Robber](../house-robber) (Medium)
-  1. [House Robber II](../house-robber-ii) (Medium)
diff --git a/problems/coin-path/coin_path.go b/problems/coin-path/coin_path.go
deleted file mode 100644
index cbf1da955..000000000
--- a/problems/coin-path/coin_path.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem656
diff --git a/problems/coin-path/coin_path_test.go b/problems/coin-path/coin_path_test.go
deleted file mode 100644
index cbf1da955..000000000
--- a/problems/coin-path/coin_path_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem656
diff --git a/problems/coloring-a-border/README.md b/problems/coloring-a-border/README.md
deleted file mode 100644
index 9ab6ec39b..000000000
--- a/problems/coloring-a-border/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../moving-stones-until-consecutive "Moving Stones Until Consecutive")
-　　　　　　　　　　　　　　　　
-[Next >](../uncrossed-lines "Uncrossed Lines")
-
-## [1034. Coloring A Border (Medium)](https://leetcode.com/problems/coloring-a-border "边框着色")
-
-<p>You are given an <code>m x n</code> integer matrix <code>grid</code>, and three integers <code>row</code>, <code>col</code>, and <code>color</code>. Each value in the grid represents the color of the grid square at that location.</p>
-
-<p>Two squares belong to the same <strong>connected component</strong> if they have the same color and are next to each other in any of the 4 directions.</p>
-
-<p>The <strong>border of a connected component</strong> is all the squares in the connected component that are either <strong>4-directionally</strong> adjacent to a square not in the component, or on the boundary of the grid (the first or last row or column).</p>
-
-<p>You should color the <strong>border</strong> of the <strong>connected component</strong> that contains the square <code>grid[row][col]</code> with <code>color</code>.</p>
-
-<p>Return <em>the final grid</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> grid = [[1,1],[1,2]], row = 0, col = 0, color = 3
-<strong>Output:</strong> [[3,3],[3,2]]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> grid = [[1,2,2],[2,3,2]], row = 0, col = 1, color = 3
-<strong>Output:</strong> [[1,3,3],[2,3,3]]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> grid = [[1,1,1],[1,1,1],[1,1,1]], row = 1, col = 1, color = 2
-<strong>Output:</strong> [[2,2,2],[2,1,2],[2,2,2]]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>1 &lt;= grid[i][j], color &lt;= 1000</code></li>
-	<li><code>0 &lt;= row &lt; m</code></li>
-	<li><code>0 &lt;= col &lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Island Perimeter](../island-perimeter) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a DFS to find every square in the component.  Then for each square, color it if it has a neighbor that is outside the grid or a different color.
-</details>
diff --git a/problems/coloring-a-border/coloring_a_border.go b/problems/coloring-a-border/coloring_a_border.go
deleted file mode 100644
index a66158b22..000000000
--- a/problems/coloring-a-border/coloring_a_border.go
+++ /dev/null
@@ -1,52 +0,0 @@
-package problem1034
-
-var dx = []int{0, 0, 1, -1}
-var dy = []int{1, -1, 0, 0}
-
-func colorBorder(grid [][]int, x0 int, y0 int, color int) [][]int {
-	m, n := len(grid), len(grid[0])
-	c := grid[x0][y0]
-
-	isBorder := func(x, y int) bool {
-		return x == 0 || x == m-1 ||
-			y == 0 || y == n-1 ||
-			grid[x][y-1] != c ||
-			grid[x][y+1] != c ||
-			grid[x-1][y] != c ||
-			grid[x+1][y] != c
-	}
-
-	connected := make([][2]int, 1, 1024)
-	hasSeen := [51][51]bool{}
-
-	connected[0] = [2]int{x0, y0}
-	hasSeen[x0][y0] = true
-
-	borders := make([][2]int, 0, 1024)
-	for len(connected) > 0 {
-		size := len(connected)
-		for i := 0; i < size; i++ {
-			p := connected[i]
-			if isBorder(p[0], p[1]) {
-				borders = append(borders, p)
-			}
-			for k := 0; k < 4; k++ {
-				x, y := p[0]+dx[k], p[1]+dy[k]
-				if 0 <= x && x < m &&
-					0 <= y && y < n &&
-					grid[x][y] == c &&
-					!hasSeen[x][y] {
-					connected = append(connected, [2]int{x, y})
-					hasSeen[x][y] = true
-				}
-			}
-		}
-		connected = connected[size:]
-	}
-
-	for _, b := range borders {
-		grid[b[0]][b[1]] = color
-	}
-
-	return grid
-}
diff --git a/problems/combination-sum-ii/README.md b/problems/combination-sum-ii/README.md
deleted file mode 100644
index fa8221b01..000000000
--- a/problems/combination-sum-ii/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../combination-sum "Combination Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../first-missing-positive "First Missing Positive")
-
-## [40. Combination Sum II (Medium)](https://leetcode.com/problems/combination-sum-ii "组合总和 II")
-
-<p>Given a collection of candidate numbers (<code>candidates</code>) and a target number (<code>target</code>), find all unique combinations in <code>candidates</code>&nbsp;where the candidate numbers sum to <code>target</code>.</p>
-
-<p>Each number in <code>candidates</code>&nbsp;may only be used <strong>once</strong> in the combination.</p>
-
-<p><strong>Note:</strong>&nbsp;The solution set must not contain duplicate combinations.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> candidates = [10,1,2,7,6,1,5], target = 8
-<strong>Output:</strong> 
-[
-[1,1,6],
-[1,2,5],
-[1,7],
-[2,6]
-]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> candidates = [2,5,2,1,2], target = 5
-<strong>Output:</strong> 
-[
-[1,2,2],
-[5]
-]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;candidates.length &lt;= 100</code></li>
-	<li><code>1 &lt;=&nbsp;candidates[i] &lt;= 50</code></li>
-	<li><code>1 &lt;= target &lt;= 30</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Combination Sum](../combination-sum) (Medium)
diff --git a/problems/combination-sum-ii/combination_sum_ii.go b/problems/combination-sum-ii/combination_sum_ii.go
deleted file mode 100644
index b3a3fdcf7..000000000
--- a/problems/combination-sum-ii/combination_sum_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem40
diff --git a/problems/combination-sum-ii/combination_sum_ii_test.go b/problems/combination-sum-ii/combination_sum_ii_test.go
deleted file mode 100644
index b3a3fdcf7..000000000
--- a/problems/combination-sum-ii/combination_sum_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem40
diff --git a/problems/combination-sum-iii/README.md b/problems/combination-sum-iii/README.md
deleted file mode 100644
index 4f08564db..000000000
--- a/problems/combination-sum-iii/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-largest-element-in-an-array "Kth Largest Element in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../contains-duplicate "Contains Duplicate")
-
-## [216. Combination Sum III (Medium)](https://leetcode.com/problems/combination-sum-iii "组合总和 III")
-
-<p>Find all valid combinations of <code>k</code> numbers that sum up to <code>n</code> such that the following conditions are true:</p>
-
-<ul>
-	<li>Only numbers <code>1</code> through <code>9</code> are used.</li>
-	<li>Each number is used <strong>at most once</strong>.</li>
-</ul>
-
-<p>Return <em>a list of all possible valid combinations</em>. The list must not contain the same combination twice, and the combinations may be returned in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3, n = 7
-<strong>Output:</strong> [[1,2,4]]
-<strong>Explanation:</strong>
-1 + 2 + 4 = 7
-There are no other valid combinations.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3, n = 9
-<strong>Output:</strong> [[1,2,6],[1,3,5],[2,3,4]]
-<strong>Explanation:</strong>
-1 + 2 + 6 = 9
-1 + 3 + 5 = 9
-2 + 3 + 4 = 9
-There are no other valid combinations.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 4, n = 1
-<strong>Output:</strong> []
-<strong>Explanation:</strong> There are no valid combinations.
-Using 4 different numbers in the range [1,9], the smallest sum we can get is 1+2+3+4 = 10 and since 10 &gt; 1, there are no valid combination.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3, n = 2
-<strong>Output:</strong> []
-<strong>Explanation:</strong> There are no valid combinations.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 9, n = 45
-<strong>Output:</strong> [[1,2,3,4,5,6,7,8,9]]
-<strong>Explanation:</strong>
-1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45
-There are no other valid combinations.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= k &lt;= 9</code></li>
-	<li><code>1 &lt;= n &lt;= 60</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Combination Sum](../combination-sum) (Medium)
diff --git a/problems/combination-sum-iii/combination_sum_iii.go b/problems/combination-sum-iii/combination_sum_iii.go
deleted file mode 100644
index bb369fb4a..000000000
--- a/problems/combination-sum-iii/combination_sum_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem216
diff --git a/problems/combination-sum-iii/combination_sum_iii_test.go b/problems/combination-sum-iii/combination_sum_iii_test.go
deleted file mode 100644
index bb369fb4a..000000000
--- a/problems/combination-sum-iii/combination_sum_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem216
diff --git a/problems/combination-sum-iv/README.md b/problems/combination-sum-iv/README.md
deleted file mode 100644
index f9e3e5393..000000000
--- a/problems/combination-sum-iv/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../wiggle-subsequence "Wiggle Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-smallest-element-in-a-sorted-matrix "Kth Smallest Element in a Sorted Matrix")
-
-## [377. Combination Sum IV (Medium)](https://leetcode.com/problems/combination-sum-iv "组合总和 Ⅳ")
-
-<p>Given an array of <strong>distinct</strong> integers <code>nums</code> and a target integer <code>target</code>, return <em>the number of possible combinations that add up to</em>&nbsp;<code>target</code>.</p>
-
-<p>The answer is <strong>guaranteed</strong> to fit in a <strong>32-bit</strong> integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3], target = 4
-<strong>Output:</strong> 7
-<strong>Explanation:</strong>
-The possible combination ways are:
-(1, 1, 1, 1)
-(1, 1, 2)
-(1, 2, 1)
-(1, 3)
-(2, 1, 1)
-(2, 2)
-(3, 1)
-Note that different sequences are counted as different combinations.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9], target = 3
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 200</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 1000</code></li>
-	<li>All the elements of <code>nums</code> are <strong>unique</strong>.</li>
-	<li><code>1 &lt;= target &lt;= 1000</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> What if negative numbers are allowed in the given array? How does it change the problem? What limitation we need to add to the question to allow negative numbers?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Combination Sum](../combination-sum) (Medium)
diff --git a/problems/combination-sum-iv/combination_sum_iv.go b/problems/combination-sum-iv/combination_sum_iv.go
deleted file mode 100644
index 1fc28688e..000000000
--- a/problems/combination-sum-iv/combination_sum_iv.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem377
diff --git a/problems/combination-sum-iv/combination_sum_iv_test.go b/problems/combination-sum-iv/combination_sum_iv_test.go
deleted file mode 100644
index 1fc28688e..000000000
--- a/problems/combination-sum-iv/combination_sum_iv_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem377
diff --git a/problems/combination-sum/README.md b/problems/combination-sum/README.md
deleted file mode 100644
index 14716ac29..000000000
--- a/problems/combination-sum/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-and-say "Count and Say")
-　　　　　　　　　　　　　　　　
-[Next >](../combination-sum-ii "Combination Sum II")
-
-## [39. Combination Sum (Medium)](https://leetcode.com/problems/combination-sum "组合总和")
-
-<p>Given an array of <strong>distinct</strong> integers <code>candidates</code> and a target integer <code>target</code>, return <em>a list of all <strong>unique combinations</strong> of </em><code>candidates</code><em> where the chosen numbers sum to </em><code>target</code><em>.</em> You may return the combinations in <strong>any order</strong>.</p>
-
-<p>The <strong>same</strong> number may be chosen from <code>candidates</code> an <strong>unlimited number of times</strong>. Two combinations are unique if the frequency of at least one of the chosen numbers is different.</p>
-
-<p>It is <strong>guaranteed</strong> that the number of unique combinations that sum up to <code>target</code> is less than <code>150</code> combinations for the given input.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> candidates = [2,3,6,7], target = 7
-<strong>Output:</strong> [[2,2,3],[7]]
-<strong>Explanation:</strong>
-2 and 3 are candidates, and 2 + 2 + 3 = 7. Note that 2 can be used multiple times.
-7 is a candidate, and 7 = 7.
-These are the only two combinations.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> candidates = [2,3,5], target = 8
-<strong>Output:</strong> [[2,2,2,2],[2,3,3],[3,5]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> candidates = [2], target = 1
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= candidates.length &lt;= 30</code></li>
-	<li><code>1 &lt;= candidates[i] &lt;= 200</code></li>
-	<li>All elements of <code>candidates</code> are <strong>distinct</strong>.</li>
-	<li><code>1 &lt;= target &lt;= 500</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Letter Combinations of a Phone Number](../letter-combinations-of-a-phone-number) (Medium)
-  1. [Combination Sum II](../combination-sum-ii) (Medium)
-  1. [Combinations](../combinations) (Medium)
-  1. [Combination Sum III](../combination-sum-iii) (Medium)
-  1. [Factor Combinations](../factor-combinations) (Medium)
-  1. [Combination Sum IV](../combination-sum-iv) (Medium)
diff --git a/problems/combination-sum/combination_sum.go b/problems/combination-sum/combination_sum.go
deleted file mode 100644
index 6b333d23d..000000000
--- a/problems/combination-sum/combination_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem39
diff --git a/problems/combination-sum/combination_sum_test.go b/problems/combination-sum/combination_sum_test.go
deleted file mode 100644
index 6b333d23d..000000000
--- a/problems/combination-sum/combination_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem39
diff --git a/problems/combinations/README.md b/problems/combinations/README.md
deleted file mode 100644
index c9bdd2fba..000000000
--- a/problems/combinations/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-window-substring "Minimum Window Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../subsets "Subsets")
-
-## [77. Combinations (Medium)](https://leetcode.com/problems/combinations "组合")
-
-<p>Given two integers <code>n</code> and <code>k</code>, return <em>all possible combinations of</em> <code>k</code> <em>numbers out of the range</em> <code>[1, n]</code>.</p>
-
-<p>You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, k = 2
-<strong>Output:</strong>
-[
-  [2,4],
-  [3,4],
-  [2,3],
-  [1,2],
-  [1,3],
-  [1,4],
-]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, k = 1
-<strong>Output:</strong> [[1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-	<li><code>1 &lt;= k &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Combination Sum](../combination-sum) (Medium)
-  1. [Permutations](../permutations) (Medium)
diff --git a/problems/combinations/combinations.go b/problems/combinations/combinations.go
deleted file mode 100644
index be2970906..000000000
--- a/problems/combinations/combinations.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem77
diff --git a/problems/combinations/combinations_test.go b/problems/combinations/combinations_test.go
deleted file mode 100644
index be2970906..000000000
--- a/problems/combinations/combinations_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem77
diff --git a/problems/combine-two-tables/README.md b/problems/combine-two-tables/README.md
deleted file mode 100644
index f507a1bf4..000000000
--- a/problems/combine-two-tables/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../dungeon-game "Dungeon Game")
-　　　　　　　　　　　　　　　　
-[Next >](../second-highest-salary "Second Highest Salary")
-
-## [175. Combine Two Tables (Easy)](https://leetcode.com/problems/combine-two-tables "组合两个表")
-
-<p>Table: <code>Person</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| personId    | int     |
-| lastName    | varchar |
-| firstName   | varchar |
-+-------------+---------+
-personId is the primary key column for this table.
-This table contains information about the ID of some persons and their first and last names.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Table: <code>Address</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| addressId   | int     |
-| personId    | int     |
-| city        | varchar |
-| state       | varchar |
-+-------------+---------+
-addressId is the primary key column for this table.
-Each row of this table contains information about the city and state of one person with ID = PersonId.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to report the first name, last name, city, and state of each person in the <code>Person</code> table. If the address of a <code>personId</code> is not present in the <code>Address</code> table, report <code>null</code> instead.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Person table:
-+----------+----------+-----------+
-| personId | lastName | firstName |
-+----------+----------+-----------+
-| 1        | Wang     | Allen     |
-| 2        | Alice    | Bob       |
-+----------+----------+-----------+
-Address table:
-+-----------+----------+---------------+------------+
-| addressId | personId | city          | state      |
-+-----------+----------+---------------+------------+
-| 1         | 2        | New York City | New York   |
-| 2         | 3        | Leetcode      | California |
-+-----------+----------+---------------+------------+
-<strong>Output:</strong> 
-+-----------+----------+---------------+----------+
-| firstName | lastName | city          | state    |
-+-----------+----------+---------------+----------+
-| Allen     | Wang     | Null          | Null     |
-| Bob       | Alice    | New York City | New York |
-+-----------+----------+---------------+----------+
-<strong>Explanation:</strong> 
-There is no address in the address table for the personId = 1 so we return null in their city and state.
-addressId = 1 contains information about the address of personId = 2.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Employee Bonus](../employee-bonus) (Easy)
diff --git a/problems/combine-two-tables/combine_two_tables.sql b/problems/combine-two-tables/combine_two_tables.sql
deleted file mode 100644
index eb8813415..000000000
--- a/problems/combine-two-tables/combine_two_tables.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT
-    Person.FirstName,
-    Person.LastName,
-    Address.City,
-    Address.State
-FROM
-    Person
-LEFT JOIN Address ON Person.PersonId = Address.PersonId;
diff --git a/problems/combine-two-tables/mysql_schemas.sql b/problems/combine-two-tables/mysql_schemas.sql
deleted file mode 100644
index b6d12b76c..000000000
--- a/problems/combine-two-tables/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Person (personId int, firstName varchar(255), lastName varchar(255));
-Create table If Not Exists Address (addressId int, personId int, city varchar(255), state varchar(255));
-Truncate table Person;
-insert into Person (personId, lastName, firstName) values ('1', 'Wang', 'Allen');
-insert into Person (personId, lastName, firstName) values ('2', 'Alice', 'Bob');
-Truncate table Address;
-insert into Address (addressId, personId, city, state) values ('1', '2', 'New York City', 'New York');
-insert into Address (addressId, personId, city, state) values ('2', '3', 'Leetcode', 'California');
diff --git a/problems/compare-strings-by-frequency-of-the-smallest-character/README.md b/problems/compare-strings-by-frequency-of-the-smallest-character/README.md
deleted file mode 100644
index faac7ff0d..000000000
--- a/problems/compare-strings-by-frequency-of-the-smallest-character/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../invalid-transactions "Invalid Transactions")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-zero-sum-consecutive-nodes-from-linked-list "Remove Zero Sum Consecutive Nodes from Linked List")
-
-## [1170. Compare Strings by Frequency of the Smallest Character (Medium)](https://leetcode.com/problems/compare-strings-by-frequency-of-the-smallest-character "比较字符串最小字母出现频次")
-
-<p>Let the function <code>f(s)</code> be the <strong>frequency of the lexicographically smallest character</strong> in a non-empty string <code>s</code>. For example, if <code>s = &quot;dcce&quot;</code> then <code>f(s) = 2</code> because the lexicographically smallest character is <code>&#39;c&#39;</code>, which has a frequency of 2.</p>
-
-<p>You are given an array of strings <code>words</code> and another array of query strings <code>queries</code>. For each query <code>queries[i]</code>, count the <strong>number of words</strong> in <code>words</code> such that <code>f(queries[i])</code> &lt; <code>f(W)</code> for each <code>W</code> in <code>words</code>.</p>
-
-<p>Return <em>an integer array </em><code>answer</code><em>, where each </em><code>answer[i]</code><em> is the answer to the </em><code>i<sup>th</sup></code><em> query</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [&quot;cbd&quot;], words = [&quot;zaaaz&quot;]
-<strong>Output:</strong> [1]
-<strong>Explanation:</strong> On the first query we have f(&quot;cbd&quot;) = 1, f(&quot;zaaaz&quot;) = 3 so f(&quot;cbd&quot;) &lt; f(&quot;zaaaz&quot;).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [&quot;bbb&quot;,&quot;cc&quot;], words = [&quot;a&quot;,&quot;aa&quot;,&quot;aaa&quot;,&quot;aaaa&quot;]
-<strong>Output:</strong> [1,2]
-<strong>Explanation:</strong> On the first query only f(&quot;bbb&quot;) &lt; f(&quot;aaaa&quot;). On the second query both f(&quot;aaa&quot;) and f(&quot;aaaa&quot;) are both &gt; f(&quot;cc&quot;).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= queries.length &lt;= 2000</code></li>
-	<li><code>1 &lt;= words.length &lt;= 2000</code></li>
-	<li><code>1 &lt;= queries[i].length, words[i].length &lt;= 10</code></li>
-	<li><code>queries[i][j]</code>, <code>words[i][j]</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each string from words calculate the leading count and store it in an array, then sort the integer array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each string from queries calculate the leading count "p" and in base of the sorted array calculated on the step 1 do a binary search to count the number of items greater than "p".
-</details>
diff --git a/problems/compare-strings-by-frequency-of-the-smallest-character/compare_strings_by_frequency_of_the_smallest_character.go b/problems/compare-strings-by-frequency-of-the-smallest-character/compare_strings_by_frequency_of_the_smallest_character.go
deleted file mode 100644
index 5434d51ab..000000000
--- a/problems/compare-strings-by-frequency-of-the-smallest-character/compare_strings_by_frequency_of_the_smallest_character.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem1170
-
-import "sort"
-
-func numSmallerByFrequency(queries []string, words []string) []int {
-	ans, m := make([]int, len(queries)), make([]int, len(words))
-	for i, w := range words {
-		m[i] = f(w)
-	}
-	sort.Ints(m)
-	for i, q := range queries {
-		t := f(q)
-		for j := len(m) - 1; j >= 0; j-- {
-			if t >= m[j] {
-				break
-			}
-			ans[i]++
-		}
-	}
-	return ans
-}
-
-func f(s string) int {
-	m, p := [26]int{}, byte(25)
-	for i := 0; i < len(s); i++ {
-		k := s[i] - 'a'
-		m[k]++
-		if p > k {
-			p = k
-		}
-	}
-	return m[p]
-}
diff --git a/problems/compare-strings-by-frequency-of-the-smallest-character/compare_strings_by_frequency_of_the_smallest_character_test.go b/problems/compare-strings-by-frequency-of-the-smallest-character/compare_strings_by_frequency_of_the_smallest_character_test.go
deleted file mode 100644
index 6aa450488..000000000
--- a/problems/compare-strings-by-frequency-of-the-smallest-character/compare_strings_by_frequency_of_the_smallest_character_test.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem1170
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []string
-	w    []string
-	want []int
-}
-
-func TestNumSmallerByFrequency(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []string{"cbd"},
-			w:    []string{"zaaaz"},
-			want: []int{1},
-		},
-		{
-			in:   []string{"bbb", "cc"},
-			w:    []string{"a", "aa", "aaa", "aaaa"},
-			want: []int{1, 2},
-		},
-	}
-	for _, tt := range tests {
-		got := numSmallerByFrequency(tt.in, tt.w)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/compare-version-numbers/README.md b/problems/compare-version-numbers/README.md
deleted file mode 100644
index 08840605a..000000000
--- a/problems/compare-version-numbers/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-gap "Maximum Gap")
-　　　　　　　　　　　　　　　　
-[Next >](../fraction-to-recurring-decimal "Fraction to Recurring Decimal")
-
-## [165. Compare Version Numbers (Medium)](https://leetcode.com/problems/compare-version-numbers "比较版本号")
-
-<p>Given two version numbers,&nbsp;<code>version1</code> and <code>version2</code>, compare them.</p>
-
-<ul>
-</ul>
-
-<p>Version numbers consist of <strong>one or more revisions</strong> joined by a dot&nbsp;<code>&#39;.&#39;</code>. Each revision&nbsp;consists of <strong>digits</strong>&nbsp;and may contain leading <strong>zeros</strong>. Every revision contains <strong>at least one character</strong>. Revisions are <strong>0-indexed from left to right</strong>, with the leftmost revision being revision 0, the next revision being revision 1, and so on. For example&nbsp;<code>2.5.33</code>&nbsp;and&nbsp;<code>0.1</code>&nbsp;are valid version numbers.</p>
-
-<p>To compare version numbers, compare their revisions in <strong>left-to-right order</strong>. Revisions are compared using their&nbsp;<strong>integer value ignoring any leading zeros</strong>. This means that revisions&nbsp;<code>1</code>&nbsp;and&nbsp;<code>001</code>&nbsp;are considered&nbsp;<strong>equal</strong>. If a version number does not specify a revision at an index, then&nbsp;<strong>treat the revision as&nbsp;<code>0</code></strong>. For example, version&nbsp;<code>1.0</code> is less than version&nbsp;<code>1.1</code>&nbsp;because their revision 0s are the same, but their revision 1s are&nbsp;<code>0</code>&nbsp;and&nbsp;<code>1</code>&nbsp;respectively, and&nbsp;<code>0 &lt; 1</code>.</p>
-
-<p><em>Return the following:</em></p>
-
-<ul>
-	<li>If <code>version1 &lt; version2</code>, return <code>-1</code>.</li>
-	<li>If <code>version1 &gt; version2</code>, return <code>1</code>.</li>
-	<li>Otherwise, return <code>0</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> version1 = &quot;1.01&quot;, version2 = &quot;1.001&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Ignoring leading zeroes, both &quot;01&quot; and &quot;001&quot; represent the same integer &quot;1&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> version1 = &quot;1.0&quot;, version2 = &quot;1.0.0&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> version1 does not specify revision 2, which means it is treated as &quot;0&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> version1 = &quot;0.1&quot;, version2 = &quot;1.1&quot;
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>&nbsp;version1&#39;s revision 0 is &quot;0&quot;, while version2&#39;s revision 0 is &quot;1&quot;. 0 &lt; 1, so version1 &lt; version2.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> version1 = &quot;1.0.1&quot;, version2 = &quot;1&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> version1 = &quot;7.5.2.4&quot;, version2 = &quot;7.5.3&quot;
-<strong>Output:</strong> -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= version1.length, version2.length &lt;= 500</code></li>
-	<li><code>version1</code> and <code>version2</code>&nbsp;only contain digits and <code>&#39;.&#39;</code>.</li>
-	<li><code>version1</code> and <code>version2</code>&nbsp;<strong>are valid version numbers</strong>.</li>
-	<li>All the given revisions in&nbsp;<code>version1</code> and <code>version2</code>&nbsp;can be stored in&nbsp;a&nbsp;<strong>32-bit integer</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/compare-version-numbers/compare_version_numbers.go b/problems/compare-version-numbers/compare_version_numbers.go
deleted file mode 100644
index 3de861791..000000000
--- a/problems/compare-version-numbers/compare_version_numbers.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem165
-
-import (
-	"strconv"
-	"strings"
-)
-
-func compareVersion(version1 string, version2 string) int {
-	v1s := strings.Split(version1, ".")
-	v2s := strings.Split(version2, ".")
-	i, l1 := 0, len(v1s)
-	j, l2 := 0, len(v2s)
-	for i < l1 || j < l2 {
-		v1, v2 := "0", "0"
-		if i < l1 {
-			v1 = v1s[i]
-			i++
-		}
-		if j < l2 {
-			v2 = v2s[j]
-			j++
-		}
-		n1, _ := strconv.Atoi(v1)
-		n2, _ := strconv.Atoi(v2)
-		if n1 != n2 {
-			if n1 < n2 {
-				return -1
-			}
-			return 1
-		}
-	}
-	return 0
-}
diff --git a/problems/compare-version-numbers/compare_version_numbers_test.go b/problems/compare-version-numbers/compare_version_numbers_test.go
deleted file mode 100644
index 730b8e16b..000000000
--- a/problems/compare-version-numbers/compare_version_numbers_test.go
+++ /dev/null
@@ -1,76 +0,0 @@
-package problem165
-
-import "testing"
-
-type testType struct {
-	v1   string
-	v2   string
-	want int
-}
-
-func TestCompareVersion(t *testing.T) {
-	tests := [...]testType{
-		{
-			v1:   "1.0.01",
-			v2:   "1.00.1",
-			want: 0,
-		},
-		{
-			v1:   "1.0.0",
-			v2:   "1",
-			want: 0,
-		},
-		{
-			v1:   "1.01",
-			v2:   "1.001",
-			want: 0,
-		},
-		{
-			v1:   "1.0",
-			v2:   "1.0.0",
-			want: 0,
-		},
-		{
-			v1:   "0.1",
-			v2:   "1.1",
-			want: -1,
-		},
-		{
-			v1:   "7.5.2.4",
-			v2:   "7.5.3",
-			want: -1,
-		},
-
-		{
-			v1:   "7.00",
-			v2:   "7.001",
-			want: -1,
-		},
-		{
-			v1:   "1.1",
-			v2:   "1.10",
-			want: -1,
-		},
-		{
-			v1:   "1.0.1",
-			v2:   "1",
-			want: 1,
-		},
-		{
-			v1:   "1.10",
-			v2:   "1.2",
-			want: 1,
-		},
-		{
-			v1:   "1.10.05",
-			v2:   "1.9.10",
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := compareVersion(tt.v1, tt.v2)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.v1, tt.v2, got, tt.want)
-		}
-	}
-}
diff --git a/problems/complement-of-base-10-integer/README.md b/problems/complement-of-base-10-integer/README.md
deleted file mode 100644
index 8b3cbb658..000000000
--- a/problems/complement-of-base-10-integer/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-binary-search-tree-from-preorder-traversal "Construct Binary Search Tree from Preorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../pairs-of-songs-with-total-durations-divisible-by-60 "Pairs of Songs With Total Durations Divisible by 60")
-
-## [1009. Complement of Base 10 Integer (Easy)](https://leetcode.com/problems/complement-of-base-10-integer "十进制整数的反码")
-
-<p>The <strong>complement</strong> of an integer is the integer you get when you flip all the <code>0</code>&#39;s to <code>1</code>&#39;s and all the <code>1</code>&#39;s to <code>0</code>&#39;s in its binary representation.</p>
-
-<ul>
-	<li>For example, The integer <code>5</code> is <code>&quot;101&quot;</code> in binary and its <strong>complement</strong> is <code>&quot;010&quot;</code> which is the integer <code>2</code>.</li>
-</ul>
-
-<p>Given an integer <code>n</code>, return <em>its complement</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 5 is &quot;101&quot; in binary, with complement &quot;010&quot; in binary, which is 2 in base-10.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> 7 is &quot;111&quot; in binary, with complement &quot;000&quot; in binary, which is 0 in base-10.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> 10 is &quot;1010&quot; in binary, with complement &quot;0101&quot; in binary, which is 5 in base-10.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt; 10<sup>9</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 476: <a href="https://leetcode.com/problems/number-complement/" target="_blank">https://leetcode.com/problems/number-complement/</a></p>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A binary number plus its complement will equal 111....111 in binary.  Also, N = 0 is a corner case.
-</details>
diff --git a/problems/complement-of-base-10-integer/complement_of_base_10_integer.go b/problems/complement-of-base-10-integer/complement_of_base_10_integer.go
deleted file mode 100644
index cd26526f1..000000000
--- a/problems/complement-of-base-10-integer/complement_of_base_10_integer.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem1009
-
-func bitwiseComplement(N int) int {
-	if N == 0 {
-		return 1
-	}
-	ans, base := 0, 1
-	for N > 0 {
-		if N&1 == 0 {
-			ans += base
-		}
-		base, N = base<<1, N>>1
-	}
-	return ans
-}
diff --git a/problems/complement-of-base-10-integer/complement_of_base_10_integer_test.go b/problems/complement-of-base-10-integer/complement_of_base_10_integer_test.go
deleted file mode 100644
index 02f48e6ce..000000000
--- a/problems/complement-of-base-10-integer/complement_of_base_10_integer_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1009
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestBitwiseComplement(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   5,
-			want: 2,
-		},
-		{
-			in:   7,
-			want: 0,
-		},
-		{
-			in:   10,
-			want: 5,
-		},
-		{
-			in:   0,
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := bitwiseComplement(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/complete-binary-tree-inserter/README.md b/problems/complete-binary-tree-inserter/README.md
deleted file mode 100644
index 976e635a4..000000000
--- a/problems/complete-binary-tree-inserter/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-sum-circular-subarray "Maximum Sum Circular Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-music-playlists "Number of Music Playlists")
-
-## [919. Complete Binary Tree Inserter (Medium)](https://leetcode.com/problems/complete-binary-tree-inserter "完全二叉树插入器")
-
-<p>A <strong>complete binary tree</strong> is a binary tree in which every level, except possibly the last, is completely filled, and all nodes are as far left as possible.</p>
-
-<p>Design an algorithm to insert a new node to a complete binary tree keeping it complete after the insertion.</p>
-
-<p>Implement the <code>CBTInserter</code> class:</p>
-
-<ul>
-	<li><code>CBTInserter(TreeNode root)</code> Initializes the data structure with the <code>root</code> of the complete binary tree.</li>
-	<li><code>int insert(int v)</code> Inserts a <code>TreeNode</code> into the tree with value <code>Node.val == val</code> so that the tree remains complete, and returns the value of the parent of the inserted <code>TreeNode</code>.</li>
-	<li><code>TreeNode get_root()</code> Returns the root node of the tree.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/03/lc-treeinsert.jpg" style="width: 500px; height: 143px;" />
-<pre>
-<strong>Input</strong>
-[&quot;CBTInserter&quot;, &quot;insert&quot;, &quot;insert&quot;, &quot;get_root&quot;]
-[[[1, 2]], [3], [4], []]
-<strong>Output</strong>
-[null, 1, 2, [1, 2, 3, 4]]
-
-<strong>Explanation</strong>
-CBTInserter cBTInserter = new CBTInserter([1, 2]);
-cBTInserter.insert(3);  // return 1
-cBTInserter.insert(4);  // return 2
-cBTInserter.get_root(); // return [1, 2, 3, 4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree will be in the range <code>[1, 1000]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 5000</code></li>
-	<li><code>root</code> is a complete binary tree.</li>
-	<li><code>0 &lt;= val &lt;= 5000</code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>insert</code> and <code>get_root</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/complete-binary-tree-inserter/complete_binary_tree_inserter.go b/problems/complete-binary-tree-inserter/complete_binary_tree_inserter.go
deleted file mode 100644
index d66fbf91f..000000000
--- a/problems/complete-binary-tree-inserter/complete_binary_tree_inserter.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem919
diff --git a/problems/complete-binary-tree-inserter/complete_binary_tree_inserter_test.go b/problems/complete-binary-tree-inserter/complete_binary_tree_inserter_test.go
deleted file mode 100644
index d66fbf91f..000000000
--- a/problems/complete-binary-tree-inserter/complete_binary_tree_inserter_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem919
diff --git a/problems/complex-number-multiplication/README.md b/problems/complex-number-multiplication/README.md
deleted file mode 100644
index 7e9767ca2..000000000
--- a/problems/complex-number-multiplication/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-binary-tree-from-string "Construct Binary Tree from String")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-bst-to-greater-tree "Convert BST to Greater Tree")
-
-## [537. Complex Number Multiplication (Medium)](https://leetcode.com/problems/complex-number-multiplication "复数乘法")
-
-<p>A <a href="https://en.wikipedia.org/wiki/Complex_number" target="_blank">complex number</a> can be represented as a string on the form <code>&quot;<strong>real</strong>+<strong>imaginary</strong>i&quot;</code> where:</p>
-
-<ul>
-	<li><code>real</code> is the real part and is an integer in the range <code>[-100, 100]</code>.</li>
-	<li><code>imaginary</code> is the imaginary part and is an integer in the range <code>[-100, 100]</code>.</li>
-	<li><code>i<sup>2</sup> == -1</code>.</li>
-</ul>
-
-<p>Given two complex numbers <code>num1</code> and <code>num2</code> as strings, return <em>a string of the complex number that represents their multiplications</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num1 = &quot;1+1i&quot;, num2 = &quot;1+1i&quot;
-<strong>Output:</strong> &quot;0+2i&quot;
-<strong>Explanation:</strong> (1 + i) * (1 + i) = 1 + i2 + 2 * i = 2i, and you need convert it to the form of 0+2i.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num1 = &quot;1+-1i&quot;, num2 = &quot;1+-1i&quot;
-<strong>Output:</strong> &quot;0+-2i&quot;
-<strong>Explanation:</strong> (1 - i) * (1 - i) = 1 + i2 - 2 * i = -2i, and you need convert it to the form of 0+-2i.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>num1</code> and <code>num2</code> are valid complex numbers.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/complex-number-multiplication/complex_number_multiplication.go b/problems/complex-number-multiplication/complex_number_multiplication.go
deleted file mode 100644
index a77001810..000000000
--- a/problems/complex-number-multiplication/complex_number_multiplication.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem537
diff --git a/problems/complex-number-multiplication/complex_number_multiplication_test.go b/problems/complex-number-multiplication/complex_number_multiplication_test.go
deleted file mode 100644
index a77001810..000000000
--- a/problems/complex-number-multiplication/complex_number_multiplication_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem537
diff --git a/problems/concatenated-words/README.md b/problems/concatenated-words/README.md
deleted file mode 100644
index eb3519814..000000000
--- a/problems/concatenated-words/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../encode-string-with-shortest-length "Encode String with Shortest Length")
-　　　　　　　　　　　　　　　　
-[Next >](../matchsticks-to-square "Matchsticks to Square")
-
-## [472. Concatenated Words (Hard)](https://leetcode.com/problems/concatenated-words "连接词")
-
-<p>Given an array of strings <code>words</code> (<strong>without duplicates</strong>), return <em>all the <strong>concatenated words</strong> in the given list of</em> <code>words</code>.</p>
-
-<p>A <strong>concatenated word</strong> is defined as a string that is comprised entirely of at least two shorter words in the given array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;cat&quot;,&quot;cats&quot;,&quot;catsdogcats&quot;,&quot;dog&quot;,&quot;dogcatsdog&quot;,&quot;hippopotamuses&quot;,&quot;rat&quot;,&quot;ratcatdogcat&quot;]
-<strong>Output:</strong> [&quot;catsdogcats&quot;,&quot;dogcatsdog&quot;,&quot;ratcatdogcat&quot;]
-<strong>Explanation:</strong> &quot;catsdogcats&quot; can be concatenated by &quot;cats&quot;, &quot;dog&quot; and &quot;cats&quot;; 
-&quot;dogcatsdog&quot; can be concatenated by &quot;dog&quot;, &quot;cats&quot; and &quot;dog&quot;; 
-&quot;ratcatdogcat&quot; can be concatenated by &quot;rat&quot;, &quot;cat&quot;, &quot;dog&quot; and &quot;cat&quot;.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;cat&quot;,&quot;dog&quot;,&quot;catdog&quot;]
-<strong>Output:</strong> [&quot;catdog&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= words[i].length &lt;= 1000</code></li>
-	<li><code>words[i]</code> consists of only lowercase English letters.</li>
-	<li><code>0 &lt;= sum(words[i].length) &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Word Break II](../word-break-ii) (Hard)
diff --git a/problems/concatenated-words/concatenated_words.go b/problems/concatenated-words/concatenated_words.go
deleted file mode 100644
index 4fabf53f2..000000000
--- a/problems/concatenated-words/concatenated_words.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem472
diff --git a/problems/concatenated-words/concatenated_words_test.go b/problems/concatenated-words/concatenated_words_test.go
deleted file mode 100644
index 4fabf53f2..000000000
--- a/problems/concatenated-words/concatenated_words_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem472
diff --git a/problems/concatenation-of-array/README.md b/problems/concatenation-of-array/README.md
deleted file mode 100644
index 1c3c142f7..000000000
--- a/problems/concatenation-of-array/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-reach-destination-in-time "Minimum Cost to Reach Destination in Time")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-length-3-palindromic-subsequences "Unique Length-3 Palindromic Subsequences")
-
-## [1929. Concatenation of Array (Easy)](https://leetcode.com/problems/concatenation-of-array "数组串联")
-
-<p>Given an integer array <code>nums</code> of length <code>n</code>, you want to create an array <code>ans</code> of length <code>2n</code> where <code>ans[i] == nums[i]</code> and <code>ans[i + n] == nums[i]</code> for <code>0 &lt;= i &lt; n</code> (<strong>0-indexed</strong>).</p>
-
-<p>Specifically, <code>ans</code> is the <strong>concatenation</strong> of two <code>nums</code> arrays.</p>
-
-<p>Return <em>the array </em><code>ans</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1]
-<strong>Output:</strong> [1,2,1,1,2,1]
-<strong>Explanation:</strong> The array ans is formed as follows:
-- ans = [nums[0],nums[1],nums[2],nums[0],nums[1],nums[2]]
-- ans = [1,2,1,1,2,1]</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,2,1]
-<strong>Output:</strong> [1,3,2,1,1,3,2,1]
-<strong>Explanation:</strong> The array ans is formed as follows:
-- ans = [nums[0],nums[1],nums[2],nums[3],nums[0],nums[1],nums[2],nums[3]]
-- ans = [1,3,2,1,1,3,2,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build an array of size 2 * n and assign num[i] to ans[i] and ans[i + n]
-</details>
diff --git a/problems/concatenation-of-consecutive-binary-numbers/README.md b/problems/concatenation-of-consecutive-binary-numbers/README.md
deleted file mode 100644
index c79a5b348..000000000
--- a/problems/concatenation-of-consecutive-binary-numbers/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-number-of-k-sum-pairs "Max Number of K-Sum Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-incompatibility "Minimum Incompatibility")
-
-## [1680. Concatenation of Consecutive Binary Numbers (Medium)](https://leetcode.com/problems/concatenation-of-consecutive-binary-numbers "连接连续二进制数字")
-
-<p>Given an integer <code>n</code>, return <em>the <strong>decimal value</strong> of the binary string formed by concatenating the binary representations of </em><code>1</code><em> to </em><code>n</code><em> in order, <strong>modulo </strong></em><code>10<sup>9 </sup>+ 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>&quot;1&quot; in binary corresponds to the decimal value 1. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 27
-<strong>Explanation: </strong>In binary, 1, 2, and 3 corresponds to &quot;1&quot;, &quot;10&quot;, and &quot;11&quot;.
-After concatenating them, we have &quot;11011&quot;, which corresponds to the decimal value 27.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 12
-<strong>Output:</strong> 505379714
-<strong>Explanation</strong>: The concatenation results in &quot;1101110010111011110001001101010111100&quot;.
-The decimal value of that is 118505380540.
-After modulo 10<sup>9</sup> + 7, the result is 505379714.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Express the nth number value in a recursion formula and think about how we can do a fast evaluation.
-</details>
diff --git a/problems/confirmation-rate/README.md b/problems/confirmation-rate/README.md
deleted file mode 100644
index 4f0f62c6c..000000000
--- a/problems/confirmation-rate/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-string-is-decomposable-into-value-equal-substrings "Check if String Is Decomposable Into Value-Equal Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-words-you-can-type "Maximum Number of Words You Can Type")
-
-## [1934. Confirmation Rate (Medium)](https://leetcode.com/problems/confirmation-rate "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/confirmation-rate/mysql_schemas.sql b/problems/confirmation-rate/mysql_schemas.sql
deleted file mode 100644
index f7683cd9e..000000000
--- a/problems/confirmation-rate/mysql_schemas.sql
+++ /dev/null
@@ -1,15 +0,0 @@
-Create table If Not Exists Signups (user_id int, time_stamp datetime);
-Create table If Not Exists Confirmations (user_id int, time_stamp datetime, action ENUM('confirmed','timeout'));
-Truncate table Signups;
-insert into Signups (user_id, time_stamp) values ('3', '2020-03-21 10:16:13');
-insert into Signups (user_id, time_stamp) values ('7', '2020-01-04 13:57:59');
-insert into Signups (user_id, time_stamp) values ('2', '2020-07-29 23:09:44');
-insert into Signups (user_id, time_stamp) values ('6', '2020-12-09 10:39:37');
-Truncate table Confirmations;
-insert into Confirmations (user_id, time_stamp, action) values ('3', '2021-01-06 03:30:46', 'timeout');
-insert into Confirmations (user_id, time_stamp, action) values ('3', '2021-07-14 14:00:00', 'timeout');
-insert into Confirmations (user_id, time_stamp, action) values ('7', '2021-06-12 11:57:29', 'confirmed');
-insert into Confirmations (user_id, time_stamp, action) values ('7', '2021-06-13 12:58:28', 'confirmed');
-insert into Confirmations (user_id, time_stamp, action) values ('7', '2021-06-14 13:59:27', 'confirmed');
-insert into Confirmations (user_id, time_stamp, action) values ('2', '2021-01-22 00:00:00', 'confirmed');
-insert into Confirmations (user_id, time_stamp, action) values ('2', '2021-02-28 23:59:59', 'timeout');
diff --git a/problems/confusing-number-ii/README.md b/problems/confusing-number-ii/README.md
deleted file mode 100644
index 22064adde..000000000
--- a/problems/confusing-number-ii/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../brace-expansion "Brace Expansion")
-　　　　　　　　　　　　　　　　
-[Next >](../duplicate-zeros "Duplicate Zeros")
-
-## [1088. Confusing Number II (Hard)](https://leetcode.com/problems/confusing-number-ii "易混淆数 II")
-
-<p>We can rotate digits by 180 degrees to form new digits. When 0, 1, 6, 8, 9 are rotated 180 degrees, they become 0, 1, 9, 8, 6 respectively. When 2, 3, 4, 5 and 7 are rotated 180 degrees, they become invalid.</p>
-
-<p>A <em>confusing number</em> is a number that when rotated 180 degrees becomes a <strong>different</strong> number with each digit valid.(Note that the rotated number can be greater than the original number.)</p>
-
-<p>Given a positive integer <code>N</code>, return the number of confusing numbers between <code>1</code> and <code>N</code>&nbsp;inclusive.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">20</span>
-<strong>Output: </strong><span id="example-output-1">6</span>
-<strong>Explanation: </strong>
-The confusing numbers are [6,9,10,16,18,19].
-6 converts to 9.
-9 converts to 6.
-10 converts to 01 which is just 1.
-16 converts to 91.
-18 converts to 81.
-19 converts to 61.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">100</span>
-<strong>Output: </strong><span id="example-output-2">19</span>
-<strong>Explanation: </strong>
-The confusing numbers are [6,9,10,16,18,19,60,61,66,68,80,81,86,89,90,91,98,99,100].
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= N &lt;= 10^9</code></li>
-</ol>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Confusing Number](../confusing-number) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Which set of digits have the valid numbers?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Only 0, 1, 6, 8, 9 are the valid set of digits, do a backtracking to generate all the numbers containing this digits and check they are valid.
-</details>
diff --git a/problems/confusing-number/README.md b/problems/confusing-number/README.md
deleted file mode 100644
index 2dab50cf9..000000000
--- a/problems/confusing-number/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-way-to-form-string "Shortest Way to Form String")
-　　　　　　　　　　　　　　　　
-[Next >](../campus-bikes "Campus Bikes")
-
-## [1056. Confusing Number (Easy)](https://leetcode.com/problems/confusing-number "易混淆数")
-
-<p>Given a number <code>N</code>, return <code>true</code> if and only if it is a <em>confusing number</em>, which satisfies the following condition:</p>
-
-<p>We can rotate digits by 180 degrees to form new digits. When 0, 1, 6, 8, 9 are rotated 180 degrees, they become 0, 1, 9, 8, 6 respectively. When 2, 3, 4, 5 and 7 are rotated 180 degrees, they become invalid. A <em>confusing number</em> is a number that when rotated 180 degrees becomes a <strong>different</strong> number with each digit valid.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/23/1268_1.png" style="width: 180px; height: 90px;" /></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">6</span>
-<strong>Output: </strong><span id="example-output-1">true</span>
-<strong>Explanation: </strong>
-We get <code>9</code> after rotating <code>6</code>, <code>9</code> is a valid number and <code>9!=6</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/23/1268_2.png" style="width: 180px; height: 90px;" /></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">89</span>
-<strong>Output: </strong><span id="example-output-2">true</span>
-<strong>Explanation: </strong>
-We get <code>68</code> after rotating <code>89</code>, <code>86</code> is a valid number and <code>86!=89</code>.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/26/1268_3.png" style="width: 301px; height: 121px;" /></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-3-1">11</span>
-<strong>Output: </strong><span id="example-output-3">false</span>
-<strong>Explanation: </strong>
-We get <code>11</code> after rotating <code>11</code>, <code>11</code> is a valid number but the value remains the same, thus <code>11</code> is not a confusing number.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/03/23/1268_4.png" style="width: 180px; height: 90px;" /></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-4-1">25</span>
-<strong>Output: </strong><span id="example-output-4">false</span>
-<strong>Explanation: </strong>
-We get an invalid number after rotating <code>25</code>.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>0 &lt;= N &lt;= 10^9</code></li>
-	<li>After the rotation we can ignore leading zeros, for example if after rotation we have <code>0008</code>&nbsp;then this number is considered as just <code>8</code>.</li>
-</ol>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Strobogrammatic Number](../strobogrammatic-number) (Easy)
-  1. [Confusing Number II](../confusing-number-ii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Reverse each digit with their corresponding new digit if an invalid digit is found the return -1. After reversing the digits just compare the reversed number with the original number.
-</details>
diff --git a/problems/connecting-cities-with-minimum-cost/README.md b/problems/connecting-cities-with-minimum-cost/README.md
deleted file mode 100644
index 10856ca12..000000000
--- a/problems/connecting-cities-with-minimum-cost/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../armstrong-number "Armstrong Number")
-　　　　　　　　　　　　　　　　
-[Next >](../parallel-courses "Parallel Courses")
-
-## [1135. Connecting Cities With Minimum Cost (Medium)](https://leetcode.com/problems/connecting-cities-with-minimum-cost "最低成本联通所有城市")
-
-<p>There are <code>N</code> cities numbered from 1 to <code>N</code>.</p>
-
-<p>You are given <code>connections</code>, where each <code>connections[i] = [city1, city2, cost]</code>&nbsp;represents the cost to connect <code>city1</code> and <code>city2</code> together.&nbsp; (A <em>connection</em> is bidirectional: connecting <code>city1</code> and <code>city2</code> is the same as connecting <code>city2</code> and <code>city1</code>.)</p>
-
-<p>Return the minimum cost so that for every pair of cities, there exists a path&nbsp;of connections (possibly of length 1) that connects those two cities together.&nbsp; The cost is the sum of the connection costs used. If the task is impossible, return -1.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/04/20/1314_ex2.png" style="width: 161px; height: 141px;" /></p>
-
-<pre>
-<strong>Input: </strong>N = 3, connections = [[1,2,5],[1,3,6],[2,3,1]]
-<strong>Output: </strong>6
-<strong>Explanation: </strong>
-Choosing any 2 edges will connect all cities so we choose the minimum 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/04/20/1314_ex1.png" style="width: 136px; height: 91px;" /></p>
-
-<pre>
-<strong>Input: </strong>N = 4, connections = [[1,2,3],[3,4,4]]
-<strong>Output: </strong>-1
-<strong>Explanation: </strong>
-There is no way to connect all cities even if all edges are used.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= N &lt;= 10000</code></li>
-	<li><code>1 &lt;= connections.length &lt;= 10000</code></li>
-	<li><code>1 &lt;= connections[i][0], connections[i][1] &lt;= N</code></li>
-	<li><code>0 &lt;= connections[i][2] &lt;= 10^5</code></li>
-	<li><code>connections[i][0] != connections[i][1]</code></li>
-</ol>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Minimum Spanning Tree](../../tag/minimum-spanning-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if we model the cities as a graph?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Build a graph of cities and find the minimum spanning tree.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can use a variation of the Kruskal's algorithm for that.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Sort the edges by their cost and use a union-find data structure.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-How to check all cities are connected?
-</details>
-
-<details>
-<summary>Hint 6</summary>
-At the beginning we have n connected components, each time we connect two components the number of connected components is reduced by one. At the end we should end with only a single component otherwise return -1.
-</details>
diff --git a/problems/consecutive-available-seats/README.md b/problems/consecutive-available-seats/README.md
deleted file mode 100644
index 867f312e7..000000000
--- a/problems/consecutive-available-seats/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../friend-requests-ii-who-has-the-most-friends "Friend Requests II: Who Has the Most Friends")
-　　　　　　　　　　　　　　　　
-[Next >](../design-compressed-string-iterator "Design Compressed String Iterator")
-
-## [603. Consecutive Available Seats (Easy)](https://leetcode.com/problems/consecutive-available-seats "连续空余座位")
-
-Several friends at a cinema ticket office would like to reserve consecutive available seats.<br />
-Can you help to query all the consecutive available seats order by the seat_id using the following <code>cinema</code> table?
-<pre>
-| seat_id | free |
-|---------|------|
-| 1       | 1    |
-| 2       | 0    |
-| 3       | 1    |
-| 4       | 1    |
-| 5       | 1    |
-</pre>
-
-<p>&nbsp;</p>
-Your query should return the following result for the sample case above.
-
-<p>&nbsp;</p>
-
-<pre>
-| seat_id |
-|---------|
-| 3       |
-| 4       |
-| 5       |
-</pre>
-<b>Note</b>:
-
-<ul>
-	<li>The seat_id is an auto increment int, and free is bool (&#39;1&#39; means free, and &#39;0&#39; means occupied.).</li>
-	<li>Consecutive available seats are more than 2(inclusive) seats consecutively available.</li>
-</ul>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/consecutive-available-seats/consecutive_available_seats.sql b/problems/consecutive-available-seats/consecutive_available_seats.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/consecutive-available-seats/consecutive_available_seats.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/consecutive-available-seats/mysql_schemas.sql b/problems/consecutive-available-seats/mysql_schemas.sql
deleted file mode 100644
index dc6635cd4..000000000
--- a/problems/consecutive-available-seats/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists cinema (seat_id int primary key auto_increment, free bool);
-Truncate table cinema;
-insert into cinema (seat_id, free) values ('1', '1');
-insert into cinema (seat_id, free) values ('2', '0');
-insert into cinema (seat_id, free) values ('3', '1');
-insert into cinema (seat_id, free) values ('4', '1');
-insert into cinema (seat_id, free) values ('5', '1');
diff --git a/problems/consecutive-characters/README.md b/problems/consecutive-characters/README.md
deleted file mode 100644
index c3ea0e124..000000000
--- a/problems/consecutive-characters/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../apples-oranges "Apples & Oranges")
-　　　　　　　　　　　　　　　　
-[Next >](../simplified-fractions "Simplified Fractions")
-
-## [1446. Consecutive Characters (Easy)](https://leetcode.com/problems/consecutive-characters "连续字符")
-
-<p>The <strong>power</strong> of the string is the maximum length of a non-empty substring that contains only one unique character.</p>
-
-<p>Given a string <code>s</code>, return <em>the <strong>power</strong> of</em> <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The substring &quot;ee&quot; is of length 2 with the character &#39;e&#39; only.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abbcccddddeeeeedcba&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The substring &quot;eeeee&quot; is of length 5 with the character &#39;e&#39; only.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 500</code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep an array power where power[i] is the maximum power of the i-th character.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The answer is max(power[i]).
-</details>
diff --git a/problems/consecutive-numbers-sum/README.md b/problems/consecutive-numbers-sum/README.md
deleted file mode 100644
index 7eae4e37c..000000000
--- a/problems/consecutive-numbers-sum/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-unique-characters-of-all-substrings-of-a-given-string "Count Unique Characters of All Substrings of a Given String")
-　　　　　　　　　　　　　　　　
-[Next >](../positions-of-large-groups "Positions of Large Groups")
-
-## [829. Consecutive Numbers Sum (Hard)](https://leetcode.com/problems/consecutive-numbers-sum "连续整数求和")
-
-<p>Given an integer <code>n</code>, return <em>the number of ways you can write </em><code>n</code><em> as the sum of consecutive positive integers.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 5 = 2 + 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 9
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 9 = 4 + 5 = 2 + 3 + 4
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 15
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> 15 = 8 + 7 = 4 + 5 + 6 = 1 + 2 + 3 + 4 + 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
diff --git a/problems/consecutive-numbers-sum/consecutive_numbers_sum.go b/problems/consecutive-numbers-sum/consecutive_numbers_sum.go
deleted file mode 100644
index eb76d7074..000000000
--- a/problems/consecutive-numbers-sum/consecutive_numbers_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem829
diff --git a/problems/consecutive-numbers-sum/consecutive_numbers_sum_test.go b/problems/consecutive-numbers-sum/consecutive_numbers_sum_test.go
deleted file mode 100644
index eb76d7074..000000000
--- a/problems/consecutive-numbers-sum/consecutive_numbers_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem829
diff --git a/problems/consecutive-numbers/README.md b/problems/consecutive-numbers/README.md
deleted file mode 100644
index 9fc244819..000000000
--- a/problems/consecutive-numbers/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-number "Largest Number")
-　　　　　　　　　　　　　　　　
-[Next >](../employees-earning-more-than-their-managers "Employees Earning More Than Their Managers")
-
-## [180. Consecutive Numbers (Medium)](https://leetcode.com/problems/consecutive-numbers "连续出现的数字")
-
-<p>Table: <code>Logs</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| id          | int     |
-| num         | varchar |
-+-------------+---------+
-id is the primary key for this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find all numbers that appear at least three times consecutively.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Logs table:
-+----+-----+
-| id | num |
-+----+-----+
-| 1  | 1   |
-| 2  | 1   |
-| 3  | 1   |
-| 4  | 2   |
-| 5  | 1   |
-| 6  | 2   |
-| 7  | 2   |
-+----+-----+
-<strong>Output:</strong> 
-+-----------------+
-| ConsecutiveNums |
-+-----------------+
-| 1               |
-+-----------------+
-<strong>Explanation:</strong> 1 is the only number that appears consecutively for at least three times.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/consecutive-numbers/consecutive_numbers.sql b/problems/consecutive-numbers/consecutive_numbers.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/consecutive-numbers/consecutive_numbers.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/consecutive-numbers/mysql_schemas.sql b/problems/consecutive-numbers/mysql_schemas.sql
deleted file mode 100644
index 0576b97dd..000000000
--- a/problems/consecutive-numbers/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Logs (id int, num int);
-Truncate table Logs;
-insert into Logs (id, num) values ('1', '1');
-insert into Logs (id, num) values ('2', '1');
-insert into Logs (id, num) values ('3', '1');
-insert into Logs (id, num) values ('4', '2');
-insert into Logs (id, num) values ('5', '1');
-insert into Logs (id, num) values ('6', '2');
-insert into Logs (id, num) values ('7', '2');
diff --git a/problems/constrained-subsequence-sum/README.md b/problems/constrained-subsequence-sum/README.md
deleted file mode 100644
index 007e5bc29..000000000
--- a/problems/constrained-subsequence-sum/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../diagonal-traverse-ii "Diagonal Traverse II")
-　　　　　　　　　　　　　　　　
-[Next >](../counting-elements "Counting Elements")
-
-## [1425. Constrained Subsequence Sum (Hard)](https://leetcode.com/problems/constrained-subsequence-sum "带限制的子序列和")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return the maximum sum of a <strong>non-empty</strong> subsequence of that array such that for every two <strong>consecutive</strong> integers in the subsequence, <code>nums[i]</code> and <code>nums[j]</code>, where <code>i &lt; j</code>, the condition <code>j - i &lt;= k</code> is satisfied.</p>
-
-<p>A <em>subsequence</em> of an array is obtained by deleting some number of elements (can be zero) from the array, leaving the remaining elements in their original order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,2,-10,5,20], k = 2
-<strong>Output:</strong> 37
-<b>Explanation:</b> The subsequence is [10, 2, 5, 20].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,-2,-3], k = 1
-<strong>Output:</strong> -1
-<b>Explanation:</b> The subsequence must be non-empty, so we choose the largest number.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,-2,-10,-5,20], k = 2
-<strong>Output:</strong> 23
-<b>Explanation:</b> The subsequence is [10, -2, -5, 20].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Monotonic Queue](../../tag/monotonic-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let dp[i] be the solution for the prefix of the array that ends at index i, if the element at index i is in the subsequence.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-dp[i] = nums[i] + max(0, dp[i-k], dp[i-k+1], ..., dp[i-1])
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use a heap with the sliding window technique to optimize the dp.
-</details>
diff --git a/problems/construct-binary-search-tree-from-preorder-traversal/README.md b/problems/construct-binary-search-tree-from-preorder-traversal/README.md
deleted file mode 100644
index e40306a8c..000000000
--- a/problems/construct-binary-search-tree-from-preorder-traversal/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-domino-rotations-for-equal-row "Minimum Domino Rotations For Equal Row")
-　　　　　　　　　　　　　　　　
-[Next >](../complement-of-base-10-integer "Complement of Base 10 Integer")
-
-## [1008. Construct Binary Search Tree from Preorder Traversal (Medium)](https://leetcode.com/problems/construct-binary-search-tree-from-preorder-traversal "前序遍历构造二叉搜索树")
-
-<p>Given an array of integers preorder, which represents the <strong>preorder traversal</strong> of a BST (i.e., <strong>binary search tree</strong>), construct the tree and return <em>its root</em>.</p>
-
-<p>It is <strong>guaranteed</strong> that there is always possible to find a binary search tree with the given requirements for the given test cases.</p>
-
-<p>A <strong>binary search tree</strong> is a binary tree where for every node, any descendant of <code>Node.left</code> has a value <strong>strictly less than</strong> <code>Node.val</code>, and any descendant of <code>Node.right</code> has a value <strong>strictly greater than</strong> <code>Node.val</code>.</p>
-
-<p>A <strong>preorder traversal</strong> of a binary tree displays the value of the node first, then traverses <code>Node.left</code>, then traverses <code>Node.right</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/03/06/1266.png" style="height: 386px; width: 590px;" />
-<pre>
-<strong>Input:</strong> preorder = [8,5,1,7,10,12]
-<strong>Output:</strong> [8,5,10,1,7,null,12]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> preorder = [1,3]
-<strong>Output:</strong> [1,null,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= preorder.length &lt;= 100</code></li>
-	<li><code>1 &lt;= preorder[i] &lt;= 1000</code></li>
-	<li>All the values of <code>preorder</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
diff --git a/problems/construct-binary-tree-from-inorder-and-postorder-traversal/README.md b/problems/construct-binary-tree-from-inorder-and-postorder-traversal/README.md
deleted file mode 100644
index f48710384..000000000
--- a/problems/construct-binary-tree-from-inorder-and-postorder-traversal/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-binary-tree-from-preorder-and-inorder-traversal "Construct Binary Tree from Preorder and Inorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-level-order-traversal-ii "Binary Tree Level Order Traversal II")
-
-## [106. Construct Binary Tree from Inorder and Postorder Traversal (Medium)](https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal "从中序与后序遍历序列构造二叉树")
-
-<p>Given two integer arrays <code>inorder</code> and <code>postorder</code> where <code>inorder</code> is the inorder traversal of a binary tree and <code>postorder</code> is the postorder traversal of the same tree, construct and return <em>the binary tree</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/tree.jpg" style="width: 277px; height: 302px;" />
-<pre>
-<strong>Input:</strong> inorder = [9,3,15,20,7], postorder = [9,15,7,20,3]
-<strong>Output:</strong> [3,9,20,null,null,15,7]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> inorder = [-1], postorder = [-1]
-<strong>Output:</strong> [-1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= inorder.length &lt;= 3000</code></li>
-	<li><code>postorder.length == inorder.length</code></li>
-	<li><code>-3000 &lt;= inorder[i], postorder[i] &lt;= 3000</code></li>
-	<li><code>inorder</code> and <code>postorder</code> consist of <strong>unique</strong> values.</li>
-	<li>Each value of <code>postorder</code> also appears in <code>inorder</code>.</li>
-	<li><code>inorder</code> is <strong>guaranteed</strong> to be the inorder traversal of the tree.</li>
-	<li><code>postorder</code> is <strong>guaranteed</strong> to be the postorder traversal of the tree.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Construct Binary Tree from Preorder and Inorder Traversal](../construct-binary-tree-from-preorder-and-inorder-traversal) (Medium)
diff --git a/problems/construct-binary-tree-from-inorder-and-postorder-traversal/construct_binary_tree_from_inorder_and_postorder_traversal.go b/problems/construct-binary-tree-from-inorder-and-postorder-traversal/construct_binary_tree_from_inorder_and_postorder_traversal.go
deleted file mode 100644
index 262e373f1..000000000
--- a/problems/construct-binary-tree-from-inorder-and-postorder-traversal/construct_binary_tree_from_inorder_and_postorder_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem106
diff --git a/problems/construct-binary-tree-from-inorder-and-postorder-traversal/construct_binary_tree_from_inorder_and_postorder_traversal_test.go b/problems/construct-binary-tree-from-inorder-and-postorder-traversal/construct_binary_tree_from_inorder_and_postorder_traversal_test.go
deleted file mode 100644
index 262e373f1..000000000
--- a/problems/construct-binary-tree-from-inorder-and-postorder-traversal/construct_binary_tree_from_inorder_and_postorder_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem106
diff --git a/problems/construct-binary-tree-from-preorder-and-inorder-traversal/README.md b/problems/construct-binary-tree-from-preorder-and-inorder-traversal/README.md
deleted file mode 100644
index a9cb8e9ca..000000000
--- a/problems/construct-binary-tree-from-preorder-and-inorder-traversal/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-depth-of-binary-tree "Maximum Depth of Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-binary-tree-from-inorder-and-postorder-traversal "Construct Binary Tree from Inorder and Postorder Traversal")
-
-## [105. Construct Binary Tree from Preorder and Inorder Traversal (Medium)](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal "从前序与中序遍历序列构造二叉树")
-
-<p>Given two integer arrays <code>preorder</code> and <code>inorder</code> where <code>preorder</code> is the preorder traversal of a binary tree and <code>inorder</code> is the inorder traversal of the same tree, construct and return <em>the binary tree</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/tree.jpg" style="width: 277px; height: 302px;" />
-<pre>
-<strong>Input:</strong> preorder = [3,9,20,15,7], inorder = [9,3,15,20,7]
-<strong>Output:</strong> [3,9,20,null,null,15,7]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> preorder = [-1], inorder = [-1]
-<strong>Output:</strong> [-1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= preorder.length &lt;= 3000</code></li>
-	<li><code>inorder.length == preorder.length</code></li>
-	<li><code>-3000 &lt;= preorder[i], inorder[i] &lt;= 3000</code></li>
-	<li><code>preorder</code> and <code>inorder</code> consist of <strong>unique</strong> values.</li>
-	<li>Each value of <code>inorder</code> also appears in <code>preorder</code>.</li>
-	<li><code>preorder</code> is <strong>guaranteed</strong> to be the preorder traversal of the tree.</li>
-	<li><code>inorder</code> is <strong>guaranteed</strong> to be the inorder traversal of the tree.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Construct Binary Tree from Inorder and Postorder Traversal](../construct-binary-tree-from-inorder-and-postorder-traversal) (Medium)
diff --git a/problems/construct-binary-tree-from-preorder-and-inorder-traversal/construct_binary_tree_from_preorder_and_inorder_traversal.go b/problems/construct-binary-tree-from-preorder-and-inorder-traversal/construct_binary_tree_from_preorder_and_inorder_traversal.go
deleted file mode 100644
index 0f02508ad..000000000
--- a/problems/construct-binary-tree-from-preorder-and-inorder-traversal/construct_binary_tree_from_preorder_and_inorder_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem105
diff --git a/problems/construct-binary-tree-from-preorder-and-inorder-traversal/construct_binary_tree_from_preorder_and_inorder_traversal_test.go b/problems/construct-binary-tree-from-preorder-and-inorder-traversal/construct_binary_tree_from_preorder_and_inorder_traversal_test.go
deleted file mode 100644
index 0f02508ad..000000000
--- a/problems/construct-binary-tree-from-preorder-and-inorder-traversal/construct_binary_tree_from_preorder_and_inorder_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem105
diff --git a/problems/construct-binary-tree-from-preorder-and-postorder-traversal/README.md b/problems/construct-binary-tree-from-preorder-and-postorder-traversal/README.md
deleted file mode 100644
index eb1be2100..000000000
--- a/problems/construct-binary-tree-from-preorder-and-postorder-traversal/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fair-candy-swap "Fair Candy Swap")
-　　　　　　　　　　　　　　　　
-[Next >](../find-and-replace-pattern "Find and Replace Pattern")
-
-## [889. Construct Binary Tree from Preorder and Postorder Traversal (Medium)](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-postorder-traversal "根据前序和后序遍历构造二叉树")
-
-<p>Given two integer arrays, <code>preorder</code> and <code>postorder</code> where <code>preorder</code> is the preorder traversal of a binary tree of <strong>distinct</strong> values and <code>postorder</code> is the postorder traversal of the same tree, reconstruct and return <em>the binary tree</em>.</p>
-
-<p>If there exist multiple answers, you can <strong>return any</strong> of them.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/24/lc-prepost.jpg" style="width: 304px; height: 265px;" />
-<pre>
-<strong>Input:</strong> preorder = [1,2,4,5,3,6,7], postorder = [4,5,2,6,7,3,1]
-<strong>Output:</strong> [1,2,3,4,5,6,7]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> preorder = [1], postorder = [1]
-<strong>Output:</strong> [1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= preorder.length &lt;= 30</code></li>
-	<li><code>1 &lt;= preorder[i] &lt;= preorder.length</code></li>
-	<li>All the values of <code>preorder</code> are <strong>unique</strong>.</li>
-	<li><code>postorder.length == preorder.length</code></li>
-	<li><code>1 &lt;= postorder[i] &lt;= postorder.length</code></li>
-	<li>All the values of <code>postorder</code> are <strong>unique</strong>.</li>
-	<li>It is guaranteed that <code>preorder</code> and <code>postorder</code> are the preorder traversal and postorder traversal of the same binary tree.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/construct-binary-tree-from-preorder-and-postorder-traversal/construct_binary_tree_from_preorder_and_postorder_traversal.go b/problems/construct-binary-tree-from-preorder-and-postorder-traversal/construct_binary_tree_from_preorder_and_postorder_traversal.go
deleted file mode 100644
index 81085b1c9..000000000
--- a/problems/construct-binary-tree-from-preorder-and-postorder-traversal/construct_binary_tree_from_preorder_and_postorder_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem889
diff --git a/problems/construct-binary-tree-from-preorder-and-postorder-traversal/construct_binary_tree_from_preorder_and_postorder_traversal_test.go b/problems/construct-binary-tree-from-preorder-and-postorder-traversal/construct_binary_tree_from_preorder_and_postorder_traversal_test.go
deleted file mode 100644
index 81085b1c9..000000000
--- a/problems/construct-binary-tree-from-preorder-and-postorder-traversal/construct_binary_tree_from_preorder_and_postorder_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem889
diff --git a/problems/construct-binary-tree-from-string/README.md b/problems/construct-binary-tree-from-string/README.md
deleted file mode 100644
index 985211a95..000000000
--- a/problems/construct-binary-tree-from-string/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../encode-and-decode-tinyurl "Encode and Decode TinyURL")
-　　　　　　　　　　　　　　　　
-[Next >](../complex-number-multiplication "Complex Number Multiplication")
-
-## [536. Construct Binary Tree from String (Medium)](https://leetcode.com/problems/construct-binary-tree-from-string "从字符串生成二叉树")
-
-<p>You need to construct a binary tree from a string consisting of parenthesis and integers. </p>
-
-<p>The whole input represents a binary tree. It contains an integer followed by zero, one or two pairs of parenthesis. The integer represents the root's value and a pair of parenthesis contains a child binary tree with the same structure. </p>
-
-<p>You always start to construct the <b>left</b> child node of the parent first if it exists.</p>
-
-<p><b>Example:</b><br />
-<pre>
-<b>Input:</b> "4(2(3)(1))(6(5))"
-<b>Output:</b> return the tree root node representing the following tree:
-
-       4
-     /   \
-    2     6
-   / \   / 
-  3   1 5   
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>There will only be <code>'('</code>,  <code>')'</code>,  <code>'-'</code> and  <code>'0'</code> ~ <code>'9'</code> in the input string.</li>
-<li>An empty tree is represented by <code>""</code> instead of <code>"()"</code>.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Construct String from Binary Tree](../construct-string-from-binary-tree) (Easy)
diff --git a/problems/construct-binary-tree-from-string/construct_binary_tree_from_string.go b/problems/construct-binary-tree-from-string/construct_binary_tree_from_string.go
deleted file mode 100644
index 65990e59e..000000000
--- a/problems/construct-binary-tree-from-string/construct_binary_tree_from_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem536
diff --git a/problems/construct-binary-tree-from-string/construct_binary_tree_from_string_test.go b/problems/construct-binary-tree-from-string/construct_binary_tree_from_string_test.go
deleted file mode 100644
index 65990e59e..000000000
--- a/problems/construct-binary-tree-from-string/construct_binary_tree_from_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem536
diff --git a/problems/construct-k-palindrome-strings/README.md b/problems/construct-k-palindrome-strings/README.md
deleted file mode 100644
index 95c994cd8..000000000
--- a/problems/construct-k-palindrome-strings/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-largest-group "Count Largest Group")
-　　　　　　　　　　　　　　　　
-[Next >](../circle-and-rectangle-overlapping "Circle and Rectangle Overlapping")
-
-## [1400. Construct K Palindrome Strings (Medium)](https://leetcode.com/problems/construct-k-palindrome-strings "构造 K 个回文字符串")
-
-<p>Given a string <code>s</code> and an integer <code>k</code>. You should construct <code>k</code> non-empty <strong>palindrome</strong> strings using <strong>all the characters</strong> in <code>s</code>.</p>
-
-<p>Return <em><strong>True</strong></em> if you can use all the characters in <code>s</code> to construct <code>k</code> palindrome strings or <em><strong>False</strong></em> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;annabelle&quot;, k = 2
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can construct two palindromes using all characters in s.
-Some possible constructions &quot;anna&quot; + &quot;elble&quot;, &quot;anbna&quot; + &quot;elle&quot;, &quot;anellena&quot; + &quot;b&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;, k = 3
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to construct 3 palindromes using all the characters of s.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;true&quot;, k = 4
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The only possible solution is to put each character in a separate string.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;yzyzyzyzyzyzyzy&quot;, k = 2
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Simply you can put all z&#39;s in one string and all y&#39;s in the other string. Both strings will be palindrome.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cr&quot;, k = 7
-<strong>Output:</strong> false
-<strong>Explanation:</strong> We don&#39;t have enough characters in s to construct 7 palindromes.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10^5</code></li>
-	<li>All characters in <code>s</code> are lower-case English letters.</li>
-	<li><code>1 &lt;= k &lt;= 10^5</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the s.length < k we cannot construct k strings from s and answer is false.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the number of characters that have odd counts is > k then the minimum number of palindrome strings we can construct is > k and answer is false.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Otherwise you can construct exactly k palindrome strings and answer is true (why ?).
-</details>
diff --git a/problems/construct-quad-tree/README.md b/problems/construct-quad-tree/README.md
deleted file mode 100644
index 54e92d898..000000000
--- a/problems/construct-quad-tree/README.md
+++ /dev/null
@@ -1,113 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-binary-search-tree-to-sorted-doubly-linked-list "Convert Binary Search Tree to Sorted Doubly Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../serialize-and-deserialize-n-ary-tree "Serialize and Deserialize N-ary Tree")
-
-## [427. Construct Quad Tree (Medium)](https://leetcode.com/problems/construct-quad-tree "建立四叉树")
-
-<p>Given a <code>n * n</code> matrix <code>grid</code> of <code>0&#39;s</code> and <code>1&#39;s</code> only. We want to represent the <code>grid</code> with a Quad-Tree.</p>
-
-<p>Return <em>the root of the Quad-Tree</em> representing the <code>grid</code>.</p>
-
-<p>Notice that you can assign the value of a node to <strong>True</strong> or <strong>False</strong> when <code>isLeaf</code> is <strong>False</strong>, and both are <strong>accepted</strong> in the answer.</p>
-
-<p>A Quad-Tree is a tree data structure in which each internal node has exactly four children. Besides, each node has two attributes:</p>
-
-<ul>
-	<li><code>val</code>: True if the node represents a grid of 1&#39;s or False if the node represents a grid of 0&#39;s.&nbsp;</li>
-	<li><code>isLeaf</code>: True if the node is leaf node on the tree or False if the node has the four children.</li>
-</ul>
-
-<pre>
-class Node {
-    public boolean val;
-&nbsp; &nbsp; public boolean isLeaf;
-&nbsp; &nbsp; public Node topLeft;
-&nbsp; &nbsp; public Node topRight;
-&nbsp; &nbsp; public Node bottomLeft;
-&nbsp; &nbsp; public Node bottomRight;
-}</pre>
-
-<p>We can construct a Quad-Tree from a two-dimensional area using the following steps:</p>
-
-<ol>
-	<li>If the current grid has the same value (i.e all <code>1&#39;s</code> or all <code>0&#39;s</code>)&nbsp;set <code>isLeaf</code>&nbsp;True and set <code>val</code> to the value of the grid and set the four children to Null and stop.</li>
-	<li>If the current grid has different values, set <code>isLeaf</code> to False and&nbsp;set <code>val</code> to any value and divide the current grid into four sub-grids as shown in the photo.</li>
-	<li>Recurse for each of the children with the proper sub-grid.</li>
-</ol>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/11/new_top.png" style="width: 777px; height: 181px;" />
-<p>If you want to know more about the Quad-Tree, you can refer to the&nbsp;<a href="https://en.wikipedia.org/wiki/Quadtree">wiki</a>.</p>
-
-<p><strong>Quad-Tree&nbsp;format:</strong></p>
-
-<p>The output represents the serialized format of a Quad-Tree using level order traversal, where <code>null</code> signifies a path terminator where no node exists below.</p>
-
-<p>It is very similar to the serialization of the binary tree. The only difference is that the node is represented as a list <code>[isLeaf, val]</code>.</p>
-
-<p>If the value of <code>isLeaf</code> or <code>val</code> is True we represent it as <strong>1</strong> in the list&nbsp;<code>[isLeaf, val]</code> and if the value of <code>isLeaf</code> or <code>val</code> is False we represent it as <strong>0</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/11/grid1.png" style="width: 777px; height: 99px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1],[1,0]]
-<strong>Output:</strong> [[0,1],[1,0],[1,1],[1,1],[1,0]]
-<strong>Explanation:</strong> The explanation of this example is shown below:
-Notice that 0 represnts False and 1 represents True in the photo representing the Quad-Tree.
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/12/e1tree.png" style="width: 777px; height: 186px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/02/12/e2mat.png" style="width: 777px; height: 343px;" /></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,1,1,0,0,0,0],[1,1,1,1,0,0,0,0],[1,1,1,1,1,1,1,1],[1,1,1,1,1,1,1,1],[1,1,1,1,0,0,0,0],[1,1,1,1,0,0,0,0],[1,1,1,1,0,0,0,0],[1,1,1,1,0,0,0,0]]
-<strong>Output:</strong> [[0,1],[1,1],[0,1],[1,1],[1,0],null,null,null,null,[1,0],[1,0],[1,1],[1,1]]
-<strong>Explanation:</strong> All values in the grid are not the same. We divide the grid into four sub-grids.
-The topLeft, bottomLeft and bottomRight each has the same value.
-The topRight have different values so we divide it into 4 sub-grids where each has the same value.
-Explanation is shown in the photo below:
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/12/e2tree.png" style="width: 777px; height: 328px;" />
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1],[1,1]]
-<strong>Output:</strong> [[1,1]]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0]]
-<strong>Output:</strong> [[1,0]]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,0,0],[1,1,0,0],[0,0,1,1],[0,0,1,1]]
-<strong>Output:</strong> [[0,1],[1,1],[1,0],[1,0],[1,1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length == grid[i].length</code></li>
-	<li><code>n == 2^x</code> where <code>0 &lt;= x &lt;= 6</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/construct-quad-tree/construct_quad_tree.go b/problems/construct-quad-tree/construct_quad_tree.go
deleted file mode 100644
index c97d117b0..000000000
--- a/problems/construct-quad-tree/construct_quad_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem427
diff --git a/problems/construct-quad-tree/construct_quad_tree.py b/problems/construct-quad-tree/construct_quad_tree.py
deleted file mode 100755
index 4a02f75b9..000000000
--- a/problems/construct-quad-tree/construct_quad_tree.py
+++ /dev/null
@@ -1,16 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a QuadTree node.
-class Node:
-    def __init__(self, val, isLeaf, topLeft, topRight, bottomLeft, bottomRight):
-        self.val = val
-        self.isLeaf = isLeaf
-        self.topLeft = topLeft
-        self.topRight = topRight
-        self.bottomLeft = bottomLeft
-        self.bottomRight = bottomRight
-"""
-class Solution:
-    def construct(self, grid: List[List[int]]) -> 'Node':
-        
\ No newline at end of file
diff --git a/problems/construct-quad-tree/construct_quad_tree_test.go b/problems/construct-quad-tree/construct_quad_tree_test.go
deleted file mode 100644
index c97d117b0..000000000
--- a/problems/construct-quad-tree/construct_quad_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem427
diff --git a/problems/construct-string-from-binary-tree/README.md b/problems/construct-string-from-binary-tree/README.md
deleted file mode 100644
index b1805ba12..000000000
--- a/problems/construct-string-from-binary-tree/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../can-place-flowers "Can Place Flowers")
-　　　　　　　　　　　　　　　　
-[Next >](../sales-person "Sales Person")
-
-## [606. Construct String from Binary Tree (Easy)](https://leetcode.com/problems/construct-string-from-binary-tree "根据二叉树创建字符串")
-
-<p>Given the <code>root</code> of a binary tree, construct a string consisting of parenthesis and integers from a binary tree with the preorder traversal way, and return it.</p>
-
-<p>Omit all the empty parenthesis pairs that do not affect the one-to-one mapping relationship between the string and the original binary tree.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/cons1-tree.jpg" style="width: 292px; height: 301px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4]
-<strong>Output:</strong> &quot;1(2(4))(3)&quot;
-<strong>Explanation:</strong> Originally, it needs to be &quot;1(2(4)())(3()())&quot;, but you need to omit all the unnecessary empty parenthesis pairs. And it will be &quot;1(2(4))(3)&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/cons2-tree.jpg" style="width: 207px; height: 293px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,null,4]
-<strong>Output:</strong> &quot;1(2()(4))(3)&quot;
-<strong>Explanation:</strong> Almost the same as the first example, except we cannot omit the first parenthesis pair to break the one-to-one mapping relationship between the input and the output.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Construct Binary Tree from String](../construct-binary-tree-from-string) (Medium)
-  1. [Find Duplicate Subtrees](../find-duplicate-subtrees) (Medium)
diff --git a/problems/construct-string-from-binary-tree/construct_string_from_binary_tree.go b/problems/construct-string-from-binary-tree/construct_string_from_binary_tree.go
deleted file mode 100644
index 870bb6aad..000000000
--- a/problems/construct-string-from-binary-tree/construct_string_from_binary_tree.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package problem606
-
-import (
-	"strconv"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func tree2str(t *TreeNode) string {
-	ans := ""
-	if t != nil {
-		ans += strconv.Itoa(t.Val)
-		if t.Left != nil {
-			ans += "(" + tree2str(t.Left) + ")"
-		} else if t.Right != nil {
-			ans += "()"
-		}
-		if t.Right != nil {
-			ans += "(" + tree2str(t.Right) + ")"
-		}
-	}
-	return ans
-}
diff --git a/problems/construct-string-from-binary-tree/construct_string_from_binary_tree_test.go b/problems/construct-string-from-binary-tree/construct_string_from_binary_tree_test.go
deleted file mode 100644
index a91f07506..000000000
--- a/problems/construct-string-from-binary-tree/construct_string_from_binary_tree_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem606
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want string
-}
-
-func TestTree2str(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3, 4},
-			want: "1(2(4))(3)",
-		},
-		{
-			in:   []int{1, 2, 3, kit.NULL, 4},
-			want: "1(2()(4))(3)",
-		},
-	}
-	for _, tt := range tests {
-		got := tree2str(kit.SliceInt2TreeNode(tt.in))
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/construct-target-array-with-multiple-sums/README.md b/problems/construct-target-array-with-multiple-sums/README.md
deleted file mode 100644
index 31a390147..000000000
--- a/problems/construct-target-array-with-multiple-sums/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-events-that-can-be-attended "Maximum Number of Events That Can Be Attended")
-　　　　　　　　　　　　　　　　
-[Next >](../activity-participants "Activity Participants")
-
-## [1354. Construct Target Array With Multiple Sums (Hard)](https://leetcode.com/problems/construct-target-array-with-multiple-sums "多次求和构造目标数组")
-
-<p>You are given an array <code>target</code> of n integers. From a starting array <code>arr</code> consisting of <code>n</code> 1&#39;s, you may perform the following procedure :</p>
-
-<ul>
-	<li>let <code>x</code> be the sum of all elements currently in your array.</li>
-	<li>choose index <code>i</code>, such that <code>0 &lt;= i &lt; n</code> and set the value of <code>arr</code> at index <code>i</code> to <code>x</code>.</li>
-	<li>You may repeat this procedure as many times as needed.</li>
-</ul>
-
-<p>Return <code>true</code> <em>if it is possible to construct the</em> <code>target</code> <em>array from</em> <code>arr</code><em>, otherwise, return</em> <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [9,3,5]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Start with arr = [1, 1, 1] 
-[1, 1, 1], sum = 3 choose index 1
-[1, 3, 1], sum = 5 choose index 2
-[1, 3, 5], sum = 9 choose index 0
-[9, 3, 5] Done
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [1,1,1,2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Impossible to create target array from [1,1,1,1].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [8,5]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == target.length</code></li>
-	<li><code>1 &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= target[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given that the sum is strictly increasing, the largest element in the target must be formed in the last step by adding the total sum in the previous step. Thus, we can simulate the process in a reversed way.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Subtract the largest with the rest of the array, and put the new element into the array. Repeat until all elements become one
-</details>
diff --git a/problems/construct-the-lexicographically-largest-valid-sequence/README.md b/problems/construct-the-lexicographically-largest-valid-sequence/README.md
deleted file mode 100644
index 7a7a64fd4..000000000
--- a/problems/construct-the-lexicographically-largest-valid-sequence/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-score-from-removing-substrings "Maximum Score From Removing Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-reconstruct-a-tree "Number Of Ways To Reconstruct A Tree")
-
-## [1718. Construct the Lexicographically Largest Valid Sequence (Medium)](https://leetcode.com/problems/construct-the-lexicographically-largest-valid-sequence "构建字典序最大的可行序列")
-
-<p>Given an integer <code>n</code>, find a sequence that satisfies all of the following:</p>
-
-<ul>
-	<li>The integer <code>1</code> occurs once in the sequence.</li>
-	<li>Each integer between <code>2</code> and <code>n</code> occurs twice in the sequence.</li>
-	<li>For every integer <code>i</code> between <code>2</code> and <code>n</code>, the <strong>distance</strong> between the two occurrences of <code>i</code> is exactly <code>i</code>.</li>
-</ul>
-
-<p>The <strong>distance</strong> between two numbers on the sequence, <code>a[i]</code> and <code>a[j]</code>, is the absolute difference of their indices, <code>|j - i|</code>.</p>
-
-<p>Return <em>the <strong>lexicographically largest</strong> sequence</em><em>. It is guaranteed that under the given constraints, there is always a solution. </em></p>
-
-<p>A sequence <code>a</code> is lexicographically larger than a sequence <code>b</code> (of the same length) if in the first position where <code>a</code> and <code>b</code> differ, sequence <code>a</code> has a number greater than the corresponding number in <code>b</code>. For example, <code>[0,1,9,0]</code> is lexicographically larger than <code>[0,1,5,6]</code> because the first position they differ is at the third number, and <code>9</code> is greater than <code>5</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> [3,1,2,3,2]
-<strong>Explanation:</strong> [2,3,2,1,3] is also a valid sequence, but [3,1,2,3,2] is the lexicographically largest valid sequence.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> [5,3,1,4,3,5,2,4,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Heuristic algorithm may work.
-</details>
diff --git a/problems/construct-the-rectangle/README.md b/problems/construct-the-rectangle/README.md
deleted file mode 100644
index 10f924dde..000000000
--- a/problems/construct-the-rectangle/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../increasing-subsequences "Increasing Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-pairs "Reverse Pairs")
-
-## [492. Construct the Rectangle (Easy)](https://leetcode.com/problems/construct-the-rectangle "构造矩形")
-
-<p>A web developer needs to know how to design a web page&#39;s size. So, given a specific rectangular web page&rsquo;s area, your job by now is to design a rectangular web page, whose length L and width W satisfy the following requirements:</p>
-
-<ol>
-	<li>The area of the rectangular web page you designed must equal to the given target area.</li>
-	<li>The width <code>W</code> should not be larger than the length <code>L</code>, which means <code>L &gt;= W</code>.</li>
-	<li>The difference between length <code>L</code> and width <code>W</code> should be as small as possible.</li>
-</ol>
-
-<p>Return <em>an array <code>[L, W]</code> where <code>L</code> and <code>W</code> are the length and width of the&nbsp;web page you designed in sequence.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> area = 4
-<strong>Output:</strong> [2,2]
-<strong>Explanation:</strong> The target area is 4, and all the possible ways to construct it are [1,4], [2,2], [4,1]. 
-But according to requirement 2, [1,4] is illegal; according to requirement 3,  [4,1] is not optimal compared to [2,2]. So the length L is 2, and the width W is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> area = 37
-<strong>Output:</strong> [37,1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> area = 122122
-<strong>Output:</strong> [427,286]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= area &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The W is always less than or equal to the square root of the area, so we start searching at sqrt(area) till we find the result.
-</details>
diff --git a/problems/construct-the-rectangle/construct_the_rectangle.go b/problems/construct-the-rectangle/construct_the_rectangle.go
deleted file mode 100644
index 85281dc4e..000000000
--- a/problems/construct-the-rectangle/construct_the_rectangle.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem492
diff --git a/problems/construct-the-rectangle/construct_the_rectangle_test.go b/problems/construct-the-rectangle/construct_the_rectangle_test.go
deleted file mode 100644
index 85281dc4e..000000000
--- a/problems/construct-the-rectangle/construct_the_rectangle_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem492
diff --git a/problems/contain-virus/README.md b/problems/contain-virus/README.md
deleted file mode 100644
index 4771a9807..000000000
--- a/problems/contain-virus/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-completing-word "Shortest Completing Word")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-corner-rectangles "Number Of Corner Rectangles")
-
-## [749. Contain Virus (Hard)](https://leetcode.com/problems/contain-virus "隔离病毒")
-
-<p>A virus is spreading rapidly, and your task is to quarantine the infected area by installing walls.</p>
-
-<p>The world is modeled as an <code>m x n</code> binary grid <code>isInfected</code>, where <code>isInfected[i][j] == 0</code> represents uninfected cells, and <code>isInfected[i][j] == 1</code> represents cells contaminated with the virus. A wall (and only one wall) can be installed between any two <strong>4-directionally</strong> adjacent cells, on the shared boundary.</p>
-
-<p>Every night, the virus spreads to all neighboring cells in all four directions unless blocked by a wall. Resources are limited. Each day, you can install walls around only one region (i.e., the affected area (continuous block of infected cells) that threatens the most uninfected cells the following night). There <strong>will never be a tie</strong>.</p>
-
-<p>Return <em>the number of walls used to quarantine all the infected regions</em>. If the world will become fully infected, return the number of walls used.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/01/virus11-grid.jpg" style="width: 500px; height: 255px;" />
-<pre>
-<strong>Input:</strong> isInfected = [[0,1,0,0,0,0,0,1],[0,1,0,0,0,0,0,1],[0,0,0,0,0,0,0,1],[0,0,0,0,0,0,0,0]]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> There are 2 contaminated regions.
-On the first day, add 5 walls to quarantine the viral region on the left. The board after the virus spreads is:
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/01/virus12edited-grid.jpg" style="width: 500px; height: 257px;" />
-On the second day, add 5 walls to quarantine the viral region on the right. The virus is fully contained.
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/01/virus13edited-grid.jpg" style="width: 500px; height: 261px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/01/virus2-grid.jpg" style="width: 653px; height: 253px;" />
-<pre>
-<strong>Input:</strong> isInfected = [[1,1,1],[1,0,1],[1,1,1]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Even though there is only one cell saved, there are 4 walls built.
-Notice that walls are only built on the shared boundary of two different cells.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> isInfected = [[1,1,1,0,0,0,0,0,0],[1,0,1,0,1,1,1,1,1],[1,1,1,0,0,0,0,0,0]]
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> The region on the left only builds two new walls.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m ==&nbsp;isInfected.length</code></li>
-	<li><code>n ==&nbsp;isInfected[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>isInfected[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-	<li>There is always a contiguous viral region throughout the described process that will <strong>infect strictly more uncontaminated squares</strong> in the next round.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The implementation is long - we want to perfrom the following steps:
-
-* Find all viral regions (connected components), additionally for each region keeping track of the frontier (neighboring uncontaminated cells), and the perimeter of the region.
-
-* Disinfect the most viral region, adding it's perimeter to the answer.
-
-* Spread the virus in the remaining regions outward by 1 square.
-</details>
diff --git a/problems/contain-virus/contain_virus.go b/problems/contain-virus/contain_virus.go
deleted file mode 100644
index 928684e83..000000000
--- a/problems/contain-virus/contain_virus.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem749
diff --git a/problems/contain-virus/contain_virus_test.go b/problems/contain-virus/contain_virus_test.go
deleted file mode 100644
index 928684e83..000000000
--- a/problems/contain-virus/contain_virus_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem749
diff --git a/problems/container-with-most-water/README.md b/problems/container-with-most-water/README.md
deleted file mode 100644
index b3b25e052..000000000
--- a/problems/container-with-most-water/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../regular-expression-matching "Regular Expression Matching")
-　　　　　　　　　　　　　　　　
-[Next >](../integer-to-roman "Integer to Roman")
-
-## [11. Container With Most Water (Medium)](https://leetcode.com/problems/container-with-most-water "盛最多水的容器")
-
-<p>You are given an integer array <code>height</code> of length <code>n</code>. There are <code>n</code> vertical lines drawn such that the two endpoints of the <code>i<sup>th</sup></code> line are <code>(i, 0)</code> and <code>(i, height[i])</code>.</p>
-
-<p>Find two lines that together with the x-axis form a container, such that the container contains the most water.</p>
-
-<p>Return <em>the maximum amount of water a container can store</em>.</p>
-
-<p><strong>Notice</strong> that you may not slant the container.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/07/17/question_11.jpg" style="width: 600px; height: 287px;" />
-<pre>
-<strong>Input:</strong> height = [1,8,6,2,5,4,8,3,7]
-<strong>Output:</strong> 49
-<strong>Explanation:</strong> The above vertical lines are represented by array [1,8,6,2,5,4,8,3,7]. In this case, the max area of water (blue section) the container can contain is 49.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> height = [1,1]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == height.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= height[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Trapping Rain Water](../trapping-rain-water) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The aim is to maximize the area formed between the vertical lines. The area of any container is calculated using the shorter line as length and the distance between the lines as the width of the rectangle.
-
-<pre>
-Area = length of shorter vertical line * distance between lines
-</pre>
-
-We can definitely get the maximum width container as the outermost lines have the maximum distance between them. However, this container <b>might not be the maximum in size</b> as one of the vertical lines of this container could be really short.
-
-<br>
-<img src="https://assets.leetcode.com/uploads/2019/10/20/hint_water_trap_1.png" width="500"/>
-
-<br>
-<img src="https://assets.leetcode.com/uploads/2019/10/20/hint_water_trap_2.png" width="500"/>
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Start with the maximum width container and go to a shorter width container if there is a vertical line longer than the current containers shorter line. This way we are compromising on the width but we are looking forward to a longer length container.
-</details>
diff --git a/problems/container-with-most-water/container_with_most_water.go b/problems/container-with-most-water/container_with_most_water.go
deleted file mode 100644
index 4cbac5812..000000000
--- a/problems/container-with-most-water/container_with_most_water.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem11
-
-func maxArea(height []int) int {
-	ans, l, r := 0, 0, len(height)-1
-	for l < r {
-		w, h := r-l, height[l]
-		if h < height[r] {
-			l++
-		} else {
-			h, r = height[r], r-1
-		}
-		if area := w * h; area > ans {
-			ans = area
-		}
-	}
-	return ans
-}
diff --git a/problems/container-with-most-water/container_with_most_water_test.go b/problems/container-with-most-water/container_with_most_water_test.go
deleted file mode 100644
index 643acc4cf..000000000
--- a/problems/container-with-most-water/container_with_most_water_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem11
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMaxArea(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 8, 6, 2, 5, 4, 8, 3, 7},
-			want: 49,
-		},
-		{
-			in:   []int{1, 8, 6, 30, 20, 6, 9, 10, 1},
-			want: 48,
-		},
-	}
-	for _, tt := range tests {
-		got := maxArea(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/contains-duplicate-ii/README.md b/problems/contains-duplicate-ii/README.md
deleted file mode 100644
index 540b57fcb..000000000
--- a/problems/contains-duplicate-ii/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-skyline-problem "The Skyline Problem")
-　　　　　　　　　　　　　　　　
-[Next >](../contains-duplicate-iii "Contains Duplicate III")
-
-## [219. Contains Duplicate II (Easy)](https://leetcode.com/problems/contains-duplicate-ii "存在重复元素 II")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <code>true</code> if there are two <strong>distinct indices</strong> <code>i</code> and <code>j</code> in the array such that <code>nums[i] == nums[j]</code> and <code>abs(i - j) &lt;= k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,1], k = 3
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,0,1,1], k = 1
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,1,2,3], k = 2
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Contains Duplicate](../contains-duplicate) (Easy)
-  1. [Contains Duplicate III](../contains-duplicate-iii) (Medium)
diff --git a/problems/contains-duplicate-ii/contains_duplicate_ii.go b/problems/contains-duplicate-ii/contains_duplicate_ii.go
deleted file mode 100644
index 74d80d079..000000000
--- a/problems/contains-duplicate-ii/contains_duplicate_ii.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem219
-
-func containsNearbyDuplicate(nums []int, k int) bool {
-	m := make(map[int]int, len(nums))
-	for i, v := range nums {
-		if p, ok := m[v]; ok && i-p <= k {
-			return true
-		}
-		m[v] = i
-	}
-	return false
-}
diff --git a/problems/contains-duplicate-ii/contains_duplicate_ii_test.go b/problems/contains-duplicate-ii/contains_duplicate_ii_test.go
deleted file mode 100644
index 71cde41cd..000000000
--- a/problems/contains-duplicate-ii/contains_duplicate_ii_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem219
-
-import "testing"
-
-type testType struct {
-	nums []int
-	k    int
-	want bool
-}
-
-func TestContainsNearbyDuplicate(t *testing.T) {
-	tests := [...]testType{
-		{
-			nums: []int{1, 2, 3, 1},
-			k:    3,
-			want: true,
-		},
-		{
-			nums: []int{1, 0, 1, 1},
-			k:    1,
-			want: true,
-		},
-		{
-			nums: []int{1, 2, 3, 1, 2, 3},
-			k:    2,
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := containsNearbyDuplicate(tt.nums, tt.k)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.nums, tt.k, got, tt.want)
-		}
-	}
-}
diff --git a/problems/contains-duplicate-iii/README.md b/problems/contains-duplicate-iii/README.md
deleted file mode 100644
index ded15be9d..000000000
--- a/problems/contains-duplicate-iii/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../contains-duplicate-ii "Contains Duplicate II")
-　　　　　　　　　　　　　　　　
-[Next >](../maximal-square "Maximal Square")
-
-## [220. Contains Duplicate III (Medium)](https://leetcode.com/problems/contains-duplicate-iii "存在重复元素 III")
-
-<p>Given an integer array <code>nums</code> and two integers <code>k</code> and <code>t</code>, return <code>true</code> if there are <strong>two distinct indices</strong> <code>i</code> and <code>j</code> in the array such that <code>abs(nums[i] - nums[j]) &lt;= t</code> and <code>abs(i - j) &lt;= k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3,1], k = 3, t = 0
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [1,0,1,1], k = 1, t = 2
-<strong>Output:</strong> true
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [1,5,9,1,5,9], k = 2, t = 3
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>0 &lt;= k &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= t &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bucket Sort](../../tag/bucket-sort/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Contains Duplicate](../contains-duplicate) (Easy)
-  1. [Contains Duplicate II](../contains-duplicate-ii) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Time complexity O(n logk)  - This will give an indication that sorting is involved for k elements.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use already existing state to evaluate next state  -  Like, a set of k sorted numbers are only needed to be tracked. When we are processing the next number in array, then we can utilize the existing sorted state and it is not necessary to sort next overlapping set of k numbers again.
-</details>
diff --git a/problems/contains-duplicate-iii/contains_duplicate_iii.go b/problems/contains-duplicate-iii/contains_duplicate_iii.go
deleted file mode 100644
index e869ba255..000000000
--- a/problems/contains-duplicate-iii/contains_duplicate_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem220
diff --git a/problems/contains-duplicate-iii/contains_duplicate_iii_test.go b/problems/contains-duplicate-iii/contains_duplicate_iii_test.go
deleted file mode 100644
index e869ba255..000000000
--- a/problems/contains-duplicate-iii/contains_duplicate_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem220
diff --git a/problems/contains-duplicate/README.md b/problems/contains-duplicate/README.md
deleted file mode 100644
index ef9f2a2d2..000000000
--- a/problems/contains-duplicate/README.md
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../combination-sum-iii "Combination Sum III")
-　　　　　　　　　　　　　　　　
-[Next >](../the-skyline-problem "The Skyline Problem")
-
-## [217. Contains Duplicate (Easy)](https://leetcode.com/problems/contains-duplicate "存在重复元素")
-
-<p>Given an integer array <code>nums</code>, return <code>true</code> if any value appears <strong>at least twice</strong> in the array, and return <code>false</code> if every element is distinct.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3,1]
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> false
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1,1,3,3,4,3,2,4,2]
-<strong>Output:</strong> true
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Contains Duplicate II](../contains-duplicate-ii) (Easy)
-  1. [Contains Duplicate III](../contains-duplicate-iii) (Medium)
diff --git a/problems/contains-duplicate/contains_duplicate.go b/problems/contains-duplicate/contains_duplicate.go
deleted file mode 100644
index 9902fa158..000000000
--- a/problems/contains-duplicate/contains_duplicate.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem217
diff --git a/problems/contains-duplicate/contains_duplicate_test.go b/problems/contains-duplicate/contains_duplicate_test.go
deleted file mode 100644
index 9902fa158..000000000
--- a/problems/contains-duplicate/contains_duplicate_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem217
diff --git a/problems/contiguous-array/README.md b/problems/contiguous-array/README.md
deleted file mode 100644
index 39dec4a3a..000000000
--- a/problems/contiguous-array/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-word-in-dictionary-through-deleting "Longest Word in Dictionary through Deleting")
-　　　　　　　　　　　　　　　　
-[Next >](../beautiful-arrangement "Beautiful Arrangement")
-
-## [525. Contiguous Array (Medium)](https://leetcode.com/problems/contiguous-array "连续数组")
-
-<p>Given a binary array <code>nums</code>, return <em>the maximum length of a contiguous subarray with an equal number of </em><code>0</code><em> and </em><code>1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> [0, 1] is the longest contiguous subarray with an equal number of 0 and 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,0]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> [0, 1] (or [1, 0]) is a longest contiguous subarray with equal number of 0 and 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums[i]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Maximum Size Subarray Sum Equals k](../maximum-size-subarray-sum-equals-k) (Medium)
diff --git a/problems/contiguous-array/contiguous_array.go b/problems/contiguous-array/contiguous_array.go
deleted file mode 100644
index bcafe8739..000000000
--- a/problems/contiguous-array/contiguous_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem525
diff --git a/problems/contiguous-array/contiguous_array_test.go b/problems/contiguous-array/contiguous_array_test.go
deleted file mode 100644
index bcafe8739..000000000
--- a/problems/contiguous-array/contiguous_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem525
diff --git a/problems/continuous-subarray-sum/README.md b/problems/continuous-subarray-sum/README.md
deleted file mode 100644
index f182bd82e..000000000
--- a/problems/continuous-subarray-sum/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-uncommon-subsequence-ii "Longest Uncommon Subsequence II")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-word-in-dictionary-through-deleting "Longest Word in Dictionary through Deleting")
-
-## [523. Continuous Subarray Sum (Medium)](https://leetcode.com/problems/continuous-subarray-sum "连续的子数组和")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <code>true</code> <em>if </em><code>nums</code><em> has a continuous subarray of size <strong>at least two</strong> whose elements sum up to a multiple of</em> <code>k</code><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>An integer <code>x</code> is a multiple of <code>k</code> if there exists an integer <code>n</code> such that <code>x = n * k</code>. <code>0</code> is <strong>always</strong> a multiple of <code>k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [23,<u>2,4</u>,6,7], k = 6
-<strong>Output:</strong> true
-<strong>Explanation:</strong> [2, 4] is a continuous subarray of size 2 whose elements sum up to 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [<u>23,2,6,4,7</u>], k = 6
-<strong>Output:</strong> true
-<strong>Explanation:</strong> [23, 2, 6, 4, 7] is an continuous subarray of size 5 whose elements sum up to 42.
-42 is a multiple of 6 because 42 = 7 * 6 and 7 is an integer.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [23,2,6,4,7], k = 13
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= sum(nums[i]) &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>1 &lt;= k &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Subarray Sum Equals K](../subarray-sum-equals-k) (Medium)
diff --git a/problems/continuous-subarray-sum/continuous_subarray_sum.go b/problems/continuous-subarray-sum/continuous_subarray_sum.go
deleted file mode 100644
index aca7a6a24..000000000
--- a/problems/continuous-subarray-sum/continuous_subarray_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem523
diff --git a/problems/continuous-subarray-sum/continuous_subarray_sum_test.go b/problems/continuous-subarray-sum/continuous_subarray_sum_test.go
deleted file mode 100644
index aca7a6a24..000000000
--- a/problems/continuous-subarray-sum/continuous_subarray_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem523
diff --git a/problems/convert-1d-array-into-2d-array/README.md b/problems/convert-1d-array-into-2d-array/README.md
deleted file mode 100644
index 1a2c6e69f..000000000
--- a/problems/convert-1d-array-into-2d-array/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../brightest-position-on-street "Brightest Position on Street")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-pairs-of-strings-with-concatenation-equal-to-target "Number of Pairs of Strings With Concatenation Equal to Target")
-
-## [2022. Convert 1D Array Into 2D Array (Easy)](https://leetcode.com/problems/convert-1d-array-into-2d-array "将一维数组转变成二维数组")
-
-<p>You are given a <strong>0-indexed</strong> 1-dimensional (1D) integer array <code>original</code>, and two integers, <code>m</code> and <code>n</code>. You are tasked with creating a 2-dimensional (2D) array with <code> m</code> rows and <code>n</code> columns using <strong>all</strong> the elements from <code>original</code>.</p>
-
-<p>The elements from indices <code>0</code> to <code>n - 1</code> (<strong>inclusive</strong>) of <code>original</code> should form the first row of the constructed 2D array, the elements from indices <code>n</code> to <code>2 * n - 1</code> (<strong>inclusive</strong>) should form the second row of the constructed 2D array, and so on.</p>
-
-<p>Return <em>an </em><code>m x n</code><em> 2D array constructed according to the above procedure, or an empty 2D array if it is impossible</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://assets.leetcode.com/uploads/2021/08/26/image-20210826114243-1.png" style="width: 500px; height: 174px;" />
-<pre>
-<strong>Input:</strong> original = [1,2,3,4], m = 2, n = 2
-<strong>Output:</strong> [[1,2],[3,4]]
-<strong>Explanation:</strong> The constructed 2D array should contain 2 rows and 2 columns.
-The first group of n=2 elements in original, [1,2], becomes the first row in the constructed 2D array.
-The second group of n=2 elements in original, [3,4], becomes the second row in the constructed 2D array.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> original = [1,2,3], m = 1, n = 3
-<strong>Output:</strong> [[1,2,3]]
-<strong>Explanation:</strong> The constructed 2D array should contain 1 row and 3 columns.
-Put all three elements in original into the first row of the constructed 2D array.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> original = [1,2], m = 1, n = 1
-<strong>Output:</strong> []
-<strong>Explanation:</strong> There are 2 elements in original.
-It is impossible to fit 2 elements in a 1x1 2D array, so return an empty 2D array.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= original.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= original[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= m, n &lt;= 4 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-When is it possible to convert original into a 2D array and when is it impossible?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-It is possible if and only if m * n == original.length
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If it is possible to convert original to a 2D array, keep an index i such that original[i] is the next element to add to the 2D array.
-</details>
diff --git a/problems/convert-a-number-to-hexadecimal/README.md b/problems/convert-a-number-to-hexadecimal/README.md
deleted file mode 100644
index 955b7b2d3..000000000
--- a/problems/convert-a-number-to-hexadecimal/README.md
+++ /dev/null
@@ -1,37 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-left-leaves "Sum of Left Leaves")
-　　　　　　　　　　　　　　　　
-[Next >](../queue-reconstruction-by-height "Queue Reconstruction by Height")
-
-## [405. Convert a Number to Hexadecimal (Easy)](https://leetcode.com/problems/convert-a-number-to-hexadecimal "数字转换为十六进制数")
-
-<p>Given an integer <code>num</code>, return <em>a string representing its hexadecimal representation</em>. For negative integers, <a href="https://en.wikipedia.org/wiki/Two%27s_complement" target="_blank">two&rsquo;s complement</a> method is used.</p>
-
-<p>All the letters in the answer string should be lowercase characters, and there should not be any leading zeros in the answer except for the zero itself.</p>
-
-<p><strong>Note:&nbsp;</strong>You are not allowed to use any built-in library method to directly solve this problem.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> num = 26
-<strong>Output:</strong> "1a"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> num = -1
-<strong>Output:</strong> "ffffffff"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= num &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/convert-a-number-to-hexadecimal/convert_a_number_to_hexadecimal.go b/problems/convert-a-number-to-hexadecimal/convert_a_number_to_hexadecimal.go
deleted file mode 100644
index f0a0db31f..000000000
--- a/problems/convert-a-number-to-hexadecimal/convert_a_number_to_hexadecimal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem405
diff --git a/problems/convert-a-number-to-hexadecimal/convert_a_number_to_hexadecimal_test.go b/problems/convert-a-number-to-hexadecimal/convert_a_number_to_hexadecimal_test.go
deleted file mode 100644
index f0a0db31f..000000000
--- a/problems/convert-a-number-to-hexadecimal/convert_a_number_to_hexadecimal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem405
diff --git a/problems/convert-binary-number-in-a-linked-list-to-integer/README.md b/problems/convert-binary-number-in-a-linked-list-to-integer/README.md
deleted file mode 100644
index 33427834a..000000000
--- a/problems/convert-binary-number-in-a-linked-list-to-integer/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-falling-path-sum-ii "Minimum Falling Path Sum II")
-　　　　　　　　　　　　　　　　
-[Next >](../sequential-digits "Sequential Digits")
-
-## [1290. Convert Binary Number in a Linked List to Integer (Easy)](https://leetcode.com/problems/convert-binary-number-in-a-linked-list-to-integer "二进制链表转整数")
-
-<p>Given <code>head</code> which is a reference node to&nbsp;a singly-linked list. The value of each node in the linked list is either 0 or 1. The linked list holds the binary representation of a number.</p>
-
-<p>Return the <em>decimal value</em> of the number in the linked list.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/12/05/graph-1.png" style="width: 426px; height: 108px;" />
-<pre>
-<strong>Input:</strong> head = [1,0,1]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> (101) in base 2 = (5) in base 10
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [0]
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1,0,0,1,0,0,1,1,1,0,0,0,0,0,0]
-<strong>Output:</strong> 18880
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [0,0]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The Linked List is not empty.</li>
-	<li>Number of nodes&nbsp;will not exceed <code>30</code>.</li>
-	<li>Each node&#39;s value is either&nbsp;<code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Traverse the linked list and store all values in a string or array. convert the values obtained to decimal value.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can solve the problem in O(1) memory using bits operation. use shift left operation ( << ) and or operation ( | ) to get the decimal value in one operation.
-</details>
diff --git a/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/README.md b/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/README.md
deleted file mode 100644
index 6380ffd0d..000000000
--- a/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-squares "Word Squares")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-quad-tree "Construct Quad Tree")
-
-## [426. Convert Binary Search Tree to Sorted Doubly Linked List (Medium)](https://leetcode.com/problems/convert-binary-search-tree-to-sorted-doubly-linked-list "将二叉搜索树转化为排序的双向链表")
-
-<p>Convert a BST to a sorted circular doubly-linked list in-place. Think of the left and right pointers as synonymous to the previous and next pointers in a doubly-linked list.</p>
-
-<p>Let&#39;s take the following BST as an example, it may help you understand the problem better:</p>
-&nbsp;
-
-<p><img src="https://assets.leetcode.com/uploads/2018/10/12/bstdlloriginalbst.png" style="width: 100%; max-width: 300px;" /></p>
-&nbsp;
-
-<p>We want to transform this BST into a circular doubly linked list. Each node in a doubly linked list has a predecessor and successor. For a circular doubly linked list, the predecessor of the first element is the last element, and the successor of the last element is the first element.</p>
-
-<p>The figure below shows the circular doubly linked list for the BST above. The &quot;head&quot; symbol means the node it points to is the smallest element of the linked list.</p>
-&nbsp;
-
-<p><img src="https://assets.leetcode.com/uploads/2018/10/12/bstdllreturndll.png" style="width: 100%; max-width: 450px;" /></p>
-&nbsp;
-
-<p>Specifically, we want to do the transformation in place. After the transformation, the left pointer of the tree node should point to its predecessor, and the right pointer should point to its successor. We should return the pointer to the first element of the linked list.</p>
-
-<p>The figure below shows the transformed BST. The solid line indicates the successor relationship, while the dashed line means the predecessor relationship.</p>
-&nbsp;
-
-<p><img src="https://assets.leetcode.com/uploads/2018/10/12/bstdllreturnbst.png" style="width: 100%; max-width: 450px;" /></p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-  [[Doubly-Linked List](../../tag/doubly-linked-list/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Inorder Traversal](../binary-tree-inorder-traversal) (Easy)
diff --git a/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/convert_binary_search_tree_to_sorted_doubly_linked_list.go b/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/convert_binary_search_tree_to_sorted_doubly_linked_list.go
deleted file mode 100644
index 6d9f2c80a..000000000
--- a/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/convert_binary_search_tree_to_sorted_doubly_linked_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem426
diff --git a/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/convert_binary_search_tree_to_sorted_doubly_linked_list_test.go b/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/convert_binary_search_tree_to_sorted_doubly_linked_list_test.go
deleted file mode 100644
index 6d9f2c80a..000000000
--- a/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/convert_binary_search_tree_to_sorted_doubly_linked_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem426
diff --git a/problems/convert-bst-to-greater-tree/README.md b/problems/convert-bst-to-greater-tree/README.md
deleted file mode 100644
index d29540249..000000000
--- a/problems/convert-bst-to-greater-tree/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../complex-number-multiplication "Complex Number Multiplication")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-time-difference "Minimum Time Difference")
-
-## [538. Convert BST to Greater Tree (Medium)](https://leetcode.com/problems/convert-bst-to-greater-tree "把二叉搜索树转换为累加树")
-
-<p>Given the <code>root</code> of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum of all keys greater than the original key in BST.</p>
-
-<p>As a reminder, a <em>binary search tree</em> is a tree that satisfies these constraints:</p>
-
-<ul>
-	<li>The left subtree of a node contains only nodes with keys <strong>less than</strong> the node&#39;s key.</li>
-	<li>The right subtree of a node contains only nodes with keys <strong>greater than</strong> the node&#39;s key.</li>
-	<li>Both the left and right subtrees must also be binary search trees.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/05/02/tree.png" style="width: 500px; height: 341px;" />
-<pre>
-<strong>Input:</strong> root = [4,1,6,0,2,5,7,null,null,null,3,null,null,null,8]
-<strong>Output:</strong> [30,36,21,36,35,26,15,null,null,null,33,null,null,null,8]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [0,null,1]
-<strong>Output:</strong> [1,null,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>4</sup> &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-	<li>All the values in the tree are <strong>unique</strong>.</li>
-	<li><code>root</code> is guaranteed to be a valid binary search tree.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 1038: <a href="https://leetcode.com/problems/binary-search-tree-to-greater-sum-tree/" target="_blank">https://leetcode.com/problems/binary-search-tree-to-greater-sum-tree/</a></p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/convert-bst-to-greater-tree/convert_bst_to_greater_tree.go b/problems/convert-bst-to-greater-tree/convert_bst_to_greater_tree.go
deleted file mode 100644
index 997891c23..000000000
--- a/problems/convert-bst-to-greater-tree/convert_bst_to_greater_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem538
diff --git a/problems/convert-bst-to-greater-tree/convert_bst_to_greater_tree_test.go b/problems/convert-bst-to-greater-tree/convert_bst_to_greater_tree_test.go
deleted file mode 100644
index 997891c23..000000000
--- a/problems/convert-bst-to-greater-tree/convert_bst_to_greater_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem538
diff --git a/problems/convert-date-format/README.md b/problems/convert-date-format/README.md
deleted file mode 100644
index 3723629a4..000000000
--- a/problems/convert-date-format/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distinct-numbers-in-each-subarray "Distinct Numbers in Each Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-population-year "Maximum Population Year")
-
-## [1853. Convert Date Format (Easy)](https://leetcode.com/problems/convert-date-format "转换日期格式")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/convert-date-format/mysql_schemas.sql b/problems/convert-date-format/mysql_schemas.sql
deleted file mode 100644
index 774d3d900..000000000
--- a/problems/convert-date-format/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create table If Not Exists Days (day date);
-Truncate table Days;
-insert into Days (day) values ('2022-04-12');
-insert into Days (day) values ('2021-08-09');
-insert into Days (day) values ('2020-06-26');
diff --git a/problems/convert-integer-to-the-sum-of-two-no-zero-integers/README.md b/problems/convert-integer-to-the-sum-of-two-no-zero-integers/README.md
deleted file mode 100644
index c06050fea..000000000
--- a/problems/convert-integer-to-the-sum-of-two-no-zero-integers/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distinct-echo-substrings "Distinct Echo Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-flips-to-make-a-or-b-equal-to-c "Minimum Flips to Make a OR b Equal to c")
-
-## [1317. Convert Integer to the Sum of Two No-Zero Integers (Easy)](https://leetcode.com/problems/convert-integer-to-the-sum-of-two-no-zero-integers "将整数转换为两个无零整数的和")
-
-<p><strong>No-Zero integer</strong> is a positive integer that <strong>does not contain any <code>0</code></strong> in its decimal representation.</p>
-
-<p>Given an integer <code>n</code>, return <em>a list of two integers</em> <code>[A, B]</code> <em>where</em>:</p>
-
-<ul>
-	<li><code>A</code> and <code>B</code> are <strong>No-Zero integers</strong>.</li>
-	<li><code>A + B = n</code></li>
-</ul>
-
-<p>The test cases are generated so that there is at least one valid solution. If there are many valid solutions you can return any of them.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> [1,1]
-<strong>Explanation:</strong> A = 1, B = 1. A + B = n and both A and B do not contain any 0 in their decimal representation.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 11
-<strong>Output:</strong> [2,9]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Loop through all elements from 1 to n.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Choose A = i and B = n - i then check if A and B are both No-Zero integers.
-</details>
diff --git a/problems/convert-sorted-array-to-binary-search-tree/README.md b/problems/convert-sorted-array-to-binary-search-tree/README.md
deleted file mode 100644
index 83415f923..000000000
--- a/problems/convert-sorted-array-to-binary-search-tree/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-level-order-traversal-ii "Binary Tree Level Order Traversal II")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-sorted-list-to-binary-search-tree "Convert Sorted List to Binary Search Tree")
-
-## [108. Convert Sorted Array to Binary Search Tree (Easy)](https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree "将有序数组转换为二叉搜索树")
-
-<p>Given an integer array <code>nums</code> where the elements are sorted in <strong>ascending order</strong>, convert <em>it to a <strong>height-balanced</strong> binary search tree</em>.</p>
-
-<p>A <strong>height-balanced</strong> binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/btree1.jpg" style="width: 302px; height: 222px;" />
-<pre>
-<strong>Input:</strong> nums = [-10,-3,0,5,9]
-<strong>Output:</strong> [0,-3,9,-10,null,5]
-<strong>Explanation:</strong> [0,-10,5,null,-3,null,9] is also accepted:
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/btree2.jpg" style="width: 302px; height: 222px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/btree.jpg" style="width: 342px; height: 142px;" />
-<pre>
-<strong>Input:</strong> nums = [1,3]
-<strong>Output:</strong> [3,1]
-<strong>Explanation:</strong> [1,3] and [3,1] are both a height-balanced BSTs.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>nums</code> is sorted in a <strong>strictly increasing</strong> order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Convert Sorted List to Binary Search Tree](../convert-sorted-list-to-binary-search-tree) (Medium)
diff --git a/problems/convert-sorted-array-to-binary-search-tree/convert_sorted_array_to_binary_search_tree.go b/problems/convert-sorted-array-to-binary-search-tree/convert_sorted_array_to_binary_search_tree.go
deleted file mode 100644
index 2db149324..000000000
--- a/problems/convert-sorted-array-to-binary-search-tree/convert_sorted_array_to_binary_search_tree.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package problem108
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func sortedArrayToBST(nums []int) *TreeNode {
-	var node *TreeNode
-	if l := len(nums); l > 0 {
-		node = &TreeNode{Val: nums[l/2]}
-		node.Left = sortedArrayToBST(nums[0 : l/2])
-		node.Right = sortedArrayToBST(nums[l/2+1:])
-	}
-	return node
-}
diff --git a/problems/convert-sorted-array-to-binary-search-tree/convert_sorted_array_to_binary_search_tree_test.go b/problems/convert-sorted-array-to-binary-search-tree/convert_sorted_array_to_binary_search_tree_test.go
deleted file mode 100644
index b9b685b0f..000000000
--- a/problems/convert-sorted-array-to-binary-search-tree/convert_sorted_array_to_binary_search_tree_test.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package problem108
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestSortedArrayToBST(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{-10, -3, 0, 5, 9},
-			want: []int{0, -3, 9, -10, kit.NULL, 5},
-		},
-	}
-	for _, tt := range tests {
-		got := kit.TreeNode2SliceInt(sortedArrayToBST(tt.in))
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/convert-sorted-list-to-binary-search-tree/README.md b/problems/convert-sorted-list-to-binary-search-tree/README.md
deleted file mode 100644
index e91c9b31d..000000000
--- a/problems/convert-sorted-list-to-binary-search-tree/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-sorted-array-to-binary-search-tree "Convert Sorted Array to Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../balanced-binary-tree "Balanced Binary Tree")
-
-## [109. Convert Sorted List to Binary Search Tree (Medium)](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree "有序链表转换二叉搜索树")
-
-<p>Given the <code>head</code> of a singly linked list where elements are <strong>sorted in ascending order</strong>, convert it to a height balanced BST.</p>
-
-<p>For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of <em>every</em> node never differ by more than 1.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/17/linked.jpg" style="width: 500px; height: 388px;" />
-<pre>
-<strong>Input:</strong> head = [-10,-3,0,5,9]
-<strong>Output:</strong> [0,-3,9,-10,null,5]
-<strong>Explanation:</strong> One possible answer is [0,-3,9,-10,null,5], which represents the shown height balanced BST.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in <code>head</code> is in the range <code>[0, 2 * 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Convert Sorted Array to Binary Search Tree](../convert-sorted-array-to-binary-search-tree) (Easy)
diff --git a/problems/convert-sorted-list-to-binary-search-tree/convert_sorted_list_to_binary_search_tree.go b/problems/convert-sorted-list-to-binary-search-tree/convert_sorted_list_to_binary_search_tree.go
deleted file mode 100644
index 919651056..000000000
--- a/problems/convert-sorted-list-to-binary-search-tree/convert_sorted_list_to_binary_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem109
diff --git a/problems/convert-sorted-list-to-binary-search-tree/convert_sorted_list_to_binary_search_tree_test.go b/problems/convert-sorted-list-to-binary-search-tree/convert_sorted_list_to_binary_search_tree_test.go
deleted file mode 100644
index 919651056..000000000
--- a/problems/convert-sorted-list-to-binary-search-tree/convert_sorted_list_to_binary_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem109
diff --git a/problems/convert-to-base-2/README.md b/problems/convert-to-base-2/README.md
deleted file mode 100644
index 93f9120b6..000000000
--- a/problems/convert-to-base-2/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-string-with-substrings-representing-1-to-n "Binary String With Substrings Representing 1 To N")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-prefix-divisible-by-5 "Binary Prefix Divisible By 5")
-
-## [1017. Convert to Base -2 (Medium)](https://leetcode.com/problems/convert-to-base-2 "负二进制转换")
-
-<p>Given an integer <code>n</code>, return <em>a binary string representing its representation in base</em> <code>-2</code>.</p>
-
-<p><strong>Note</strong> that the returned string should not have leading zeros unless the string is <code>&quot;0&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> &quot;110&quot;
-<strong>Explantion:</strong> (-2)<sup>2</sup> + (-2)<sup>1</sup> = 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> &quot;111&quot;
-<strong>Explantion:</strong> (-2)<sup>2</sup> + (-2)<sup>1</sup> + (-2)<sup>0</sup> = 3
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> &quot;100&quot;
-<strong>Explantion:</strong> (-2)<sup>2</sup> = 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Encode Number](../encode-number) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Figure out whether you need the ones digit placed or not, then shift by two.
-</details>
diff --git a/problems/convert-to-base-2/convert_to_base_2.go b/problems/convert-to-base-2/convert_to_base_2.go
deleted file mode 100644
index a23fb11d0..000000000
--- a/problems/convert-to-base-2/convert_to_base_2.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem1017
-
-func baseNeg2(N int) string {
-	if N == 0 {
-		return "0"
-	}
-
-	B := make([]byte, 0, 30)
-	for N > 0 {
-		switch N & 3 {
-		case 0, 1:
-			B = append(B, byte(N&1)+'0', '0')
-		default: // 2,3
-			B = append(B, byte(N&1)+'0', '1')
-			N += 4
-			// 2^(2n)-2^(2n-1) == 2^(2n-1)
-			// 所以，把 N 转换成二进制后，每在奇数位上看见 1 就在其左边的偶数位上加 1
-			// 就可以转换成以 -2 为基的二进制了
-		}
-		N >>= 2
-	}
-
-	swap(B)
-
-	if B[0] == '0' { // no lead 0 except for N is 0
-		B = B[1:]
-	}
-
-	return string(B)
-}
-
-func swap(B []byte) {
-	i, j := 0, len(B)-1
-	for i < j {
-		B[i], B[j] = B[j], B[i]
-		i++
-		j--
-	}
-}
diff --git a/problems/convex-polygon/README.md b/problems/convex-polygon/README.md
deleted file mode 100644
index 866c02f6d..000000000
--- a/problems/convex-polygon/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../validate-ip-address "Validate IP Address")
-　　　　　　　　　　　　　　　　
-[Next >](../implement-rand10-using-rand7 "Implement Rand10() Using Rand7()")
-
-## [469. Convex Polygon (Medium)](https://leetcode.com/problems/convex-polygon "凸多边形")
-
-<p>Given a list of points that form a polygon when joined sequentially, find if this polygon is convex <a href="https://en.wikipedia.org/wiki/Convex_polygon" target="_blank">(Convex polygon definition)</a>.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>There are at least 3 and at most 10,000 points.</li>
-	<li>Coordinates are in the range -10,000 to 10,000.</li>
-	<li>You may assume the polygon formed by given points is always a simple polygon<a href="https://en.wikipedia.org/wiki/Simple_polygon" target="_blank"> (Simple polygon definition)</a>. In other words, we ensure that exactly two edges intersect at each vertex, and that edges otherwise <b>don&#39;t intersect each other</b>.</li>
-</ol>
-
-<p>&nbsp;</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-[[0,0],[0,1],[1,1],[1,0]]
-
-Answer: True
-
-Explanation:<img src="https://assets.leetcode.com/uploads/2018/10/13/polygon_convex.png" style="width: 100px; height: 100px;" />
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-[[0,0],[0,10],[10,10],[10,0],[5,5]]
-
-Answer: False
-
-Explanation:<img src="https://assets.leetcode.com/uploads/2018/10/13/polygon_not_convex.png" style="width: 100px; height: 100px;" />
-</pre>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/convex-polygon/convex_polygon.go b/problems/convex-polygon/convex_polygon.go
deleted file mode 100644
index e39705b1f..000000000
--- a/problems/convex-polygon/convex_polygon.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem469
diff --git a/problems/convex-polygon/convex_polygon_test.go b/problems/convex-polygon/convex_polygon_test.go
deleted file mode 100644
index e39705b1f..000000000
--- a/problems/convex-polygon/convex_polygon_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem469
diff --git a/problems/coordinate-with-maximum-network-quality/README.md b/problems/coordinate-with-maximum-network-quality/README.md
deleted file mode 100644
index 6ada4d259..000000000
--- a/problems/coordinate-with-maximum-network-quality/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../mean-of-array-after-removing-some-elements "Mean of Array After Removing Some Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-sets-of-k-non-overlapping-line-segments "Number of Sets of K Non-Overlapping Line Segments")
-
-## [1620. Coordinate With Maximum Network Quality (Medium)](https://leetcode.com/problems/coordinate-with-maximum-network-quality "网络信号最好的坐标")
-
-<p>You are given an array of network towers <code>towers</code>, where <code>towers[i] = [x<sub>i</sub>, y<sub>i</sub>, q<sub>i</sub>]</code> denotes the <code>i<sup>th</sup></code> network tower with location <code>(x<sub>i</sub>, y<sub>i</sub>)</code> and quality factor <code>q<sub>i</sub></code>. All the coordinates are <strong>integral coordinates</strong> on the X-Y plane, and the distance between the two coordinates is the <strong>Euclidean distance</strong>.</p>
-
-<p>You are also given an integer <code>radius</code> where a tower is <strong>reachable</strong> if the distance is <strong>less than or equal to</strong> <code>radius</code>. Outside that distance, the signal becomes garbled, and the tower is <strong>not reachable</strong>.</p>
-
-<p>The signal quality of the <code>i<sup>th</sup></code> tower at a coordinate <code>(x, y)</code> is calculated with the formula <code>&lfloor;q<sub>i</sub> / (1 + d)&rfloor;</code>, where <code>d</code> is the distance between the tower and the coordinate. The <strong>network quality</strong> at a coordinate is the sum of the signal qualities from all the <strong>reachable</strong> towers.</p>
-
-<p>Return <em>the array </em><code>[c<sub>x</sub>, c<sub>y</sub>]</code><em> representing the <strong>integral</strong> coordinate </em><code>(c<sub>x</sub>, c<sub>y</sub>)</code><em> where the <strong>network quality</strong> is maximum. If there are multiple coordinates with the same <strong>network quality</strong>, return the lexicographically minimum <strong>non-negative</strong> coordinate.</em></p>
-
-<p><strong>Note:</strong></p>
-
-<ul>
-	<li>A coordinate <code>(x1, y1)</code> is lexicographically smaller than <code>(x2, y2)</code> if either:
-	<ul>
-		<li><code>x1 &lt; x2</code>, or</li>
-		<li><code>x1 == x2</code> and <code>y1 &lt; y2</code>.</li>
-	</ul>
-	</li>
-	<li><code>&lfloor;val&rfloor;</code> is the greatest integer less than or equal to <code>val</code> (the floor function).</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/22/untitled-diagram.png" style="width: 176px; height: 176px;" />
-<pre>
-<strong>Input:</strong> towers = [[1,2,5],[2,1,7],[3,1,9]], radius = 2
-<strong>Output:</strong> [2,1]
-<strong>Explanation:</strong> At coordinate (2, 1) the total quality is 13.
-- Quality of 7 from (2, 1) results in &lfloor;7 / (1 + sqrt(0)&rfloor; = &lfloor;7&rfloor; = 7
-- Quality of 5 from (1, 2) results in &lfloor;5 / (1 + sqrt(2)&rfloor; = &lfloor;2.07&rfloor; = 2
-- Quality of 9 from (3, 1) results in &lfloor;9 / (1 + sqrt(1)&rfloor; = &lfloor;4.5&rfloor; = 4
-No other coordinate has a higher network quality.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> towers = [[23,11,21]], radius = 9
-<strong>Output:</strong> [23,11]
-<strong>Explanation:</strong> Since there is only one tower, the network quality is highest right at the tower&#39;s location.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> towers = [[1,2,13],[2,1,7],[0,1,9]], radius = 2
-<strong>Output:</strong> [1,2]
-<strong>Explanation:</strong> Coordinate (1, 2) has the highest network quality.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= towers.length &lt;= 50</code></li>
-	<li><code>towers[i].length == 3</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub>, q<sub>i</sub> &lt;= 50</code></li>
-	<li><code>1 &lt;= radius &lt;= 50</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The constraints are small enough to consider every possible coordinate and calculate its quality.
-</details>
diff --git a/problems/copy-list-with-random-pointer/README.md b/problems/copy-list-with-random-pointer/README.md
deleted file mode 100644
index d6f283200..000000000
--- a/problems/copy-list-with-random-pointer/README.md
+++ /dev/null
@@ -1,103 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../single-number-ii "Single Number II")
-　　　　　　　　　　　　　　　　
-[Next >](../word-break "Word Break")
-
-## [138. Copy List with Random Pointer (Medium)](https://leetcode.com/problems/copy-list-with-random-pointer "复制带随机指针的链表")
-
-<p>A linked list of length <code>n</code> is given such that each node contains an additional random pointer, which could point to any node in the list, or <code>null</code>.</p>
-
-<p>Construct a <a href="https://en.wikipedia.org/wiki/Object_copying#Deep_copy" target="_blank"><strong>deep copy</strong></a> of the list. The deep copy should consist of exactly <code>n</code> <strong>brand new</strong> nodes, where each new node has its value set to the value of its corresponding original node. Both the <code>next</code> and <code>random</code> pointer of the new nodes should point to new nodes in the copied list such that the pointers in the original list and copied list represent the same list state. <strong>None of the pointers in the new list should point to nodes in the original list</strong>.</p>
-
-<p>For example, if there are two nodes <code>X</code> and <code>Y</code> in the original list, where <code>X.random --&gt; Y</code>, then for the corresponding two nodes <code>x</code> and <code>y</code> in the copied list, <code>x.random --&gt; y</code>.</p>
-
-<p>Return <em>the head of the copied linked list</em>.</p>
-
-<p>The linked list is represented in the input/output as a list of <code>n</code> nodes. Each node is represented as a pair of <code>[val, random_index]</code> where:</p>
-
-<ul>
-	<li><code>val</code>: an integer representing <code>Node.val</code></li>
-	<li><code>random_index</code>: the index of the node (range from <code>0</code> to <code>n-1</code>) that the <code>random</code> pointer points to, or <code>null</code> if it does not point to any node.</li>
-</ul>
-
-<p>Your code will <strong>only</strong> be given the <code>head</code> of the original linked list.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/e1.png" style="width: 700px; height: 142px;" />
-<pre>
-<strong>Input:</strong> head = [[7,null],[13,0],[11,4],[10,2],[1,0]]
-<strong>Output:</strong> [[7,null],[13,0],[11,4],[10,2],[1,0]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/e2.png" style="width: 700px; height: 114px;" />
-<pre>
-<strong>Input:</strong> head = [[1,1],[2,1]]
-<strong>Output:</strong> [[1,1],[2,1]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/e3.png" style="width: 700px; height: 122px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> head = [[3,null],[3,0],[3,null]]
-<strong>Output:</strong> [[3,null],[3,0],[3,null]]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = []
-<strong>Output:</strong> []
-<strong>Explanation:</strong> The given linked list is empty (null pointer), so return null.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 1000</code></li>
-	<li><code>-10000 &lt;= Node.val &lt;= 10000</code></li>
-	<li><code>Node.random</code> is <code>null</code> or is pointing to some node in the linked list.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Clone Graph](../clone-graph) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Just iterate the linked list and create copies of the nodes on the go. Since a node can be referenced from multiple nodes due to the random pointers, make sure you are not making multiple copies of the same node.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You may want to use extra space to keep <b>old node ---> new node</b> mapping to prevent creating multiples copies of same node.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We can avoid using extra space for old node ---> new node mapping, by tweaking the original linked list. Simply interweave the nodes of the old and copied list. 
-For e.g.
-<pre>
-Old List: A --> B --> C --> D
-InterWeaved List: A --> A' --> B --> B' --> C --> C' --> D --> D'
-</pre>
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The interweaving is done using <b>next</b> pointers and we can make use of interweaved structure to get the correct reference nodes for <b>random</b> pointers.
-</details>
diff --git a/problems/copy-list-with-random-pointer/copy_list_with_random_pointer.go b/problems/copy-list-with-random-pointer/copy_list_with_random_pointer.go
deleted file mode 100644
index 37ad5883b..000000000
--- a/problems/copy-list-with-random-pointer/copy_list_with_random_pointer.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem138
diff --git a/problems/copy-list-with-random-pointer/copy_list_with_random_pointer.py b/problems/copy-list-with-random-pointer/copy_list_with_random_pointer.py
deleted file mode 100755
index bf723165f..000000000
--- a/problems/copy-list-with-random-pointer/copy_list_with_random_pointer.py
+++ /dev/null
@@ -1,13 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a Node.
-class Node:
-    def __init__(self, val, next, random):
-        self.val = val
-        self.next = next
-        self.random = random
-"""
-class Solution:
-    def copyRandomList(self, head: 'Node') -> 'Node':
-        
\ No newline at end of file
diff --git a/problems/copy-list-with-random-pointer/copy_list_with_random_pointer_test.go b/problems/copy-list-with-random-pointer/copy_list_with_random_pointer_test.go
deleted file mode 100644
index 37ad5883b..000000000
--- a/problems/copy-list-with-random-pointer/copy_list_with_random_pointer_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem138
diff --git a/problems/corporate-flight-bookings/README.md b/problems/corporate-flight-bookings/README.md
deleted file mode 100644
index 63e874b4c..000000000
--- a/problems/corporate-flight-bookings/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../defanging-an-ip-address "Defanging an IP Address")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-nodes-and-return-forest "Delete Nodes And Return Forest")
-
-## [1109. Corporate Flight Bookings (Medium)](https://leetcode.com/problems/corporate-flight-bookings "航班预订统计")
-
-<p>There are <code>n</code> flights that are labeled from <code>1</code> to <code>n</code>.</p>
-
-<p>You are given an array of flight bookings <code>bookings</code>, where <code>bookings[i] = [first<sub>i</sub>, last<sub>i</sub>, seats<sub>i</sub>]</code> represents a booking for flights <code>first<sub>i</sub></code> through <code>last<sub>i</sub></code> (<strong>inclusive</strong>) with <code>seats<sub>i</sub></code> seats reserved for <strong>each flight</strong> in the range.</p>
-
-<p>Return <em>an array </em><code>answer</code><em> of length </em><code>n</code><em>, where </em><code>answer[i]</code><em> is the total number of seats reserved for flight </em><code>i</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> bookings = [[1,2,10],[2,3,20],[2,5,25]], n = 5
-<strong>Output:</strong> [10,55,45,25,25]
-<strong>Explanation:</strong>
-Flight labels:        1   2   3   4   5
-Booking 1 reserved:  10  10
-Booking 2 reserved:      20  20
-Booking 3 reserved:      25  25  25  25
-Total seats:         10  55  45  25  25
-Hence, answer = [10,55,45,25,25]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> bookings = [[1,2,10],[2,2,15]], n = 2
-<strong>Output:</strong> [10,25]
-<strong>Explanation:</strong>
-Flight labels:        1   2
-Booking 1 reserved:  10  10
-Booking 2 reserved:      15
-Total seats:         10  25
-Hence, answer = [10,25]
-
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= bookings.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>bookings[i].length == 3</code></li>
-	<li><code>1 &lt;= first<sub>i</sub> &lt;= last<sub>i</sub> &lt;= n</code></li>
-	<li><code>1 &lt;= seats<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
diff --git a/problems/corporate-flight-bookings/corporate_flight_bookings.go b/problems/corporate-flight-bookings/corporate_flight_bookings.go
deleted file mode 100644
index 120b8a289..000000000
--- a/problems/corporate-flight-bookings/corporate_flight_bookings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1109
diff --git a/problems/correct-a-binary-tree/README.md b/problems/correct-a-binary-tree/README.md
deleted file mode 100644
index a98761723..000000000
--- a/problems/correct-a-binary-tree/README.md
+++ /dev/null
@@ -1,27 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximize-grid-happiness "Maximize Grid Happiness")
-　　　　　　　　　　　　　　　　
-[Next >](../average-time-of-process-per-machine "Average Time of Process per Machine")
-
-## [1660. Correct a Binary Tree (Medium)](https://leetcode.com/problems/correct-a-binary-tree "纠正二叉树")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you traverse the tree from right to left, the invalid node will point to a node that has already been visited.
-</details>
diff --git a/problems/count-all-possible-routes/README.md b/problems/count-all-possible-routes/README.md
deleted file mode 100644
index 5de9e8ec3..000000000
--- a/problems/count-all-possible-routes/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-subarray-to-be-removed-to-make-array-sorted "Shortest Subarray to be Removed to Make Array Sorted")
-　　　　　　　　　　　　　　　　
-[Next >](../replace-all-s-to-avoid-consecutive-repeating-characters "Replace All ?'s to Avoid Consecutive Repeating Characters")
-
-## [1575. Count All Possible Routes (Hard)](https://leetcode.com/problems/count-all-possible-routes "统计所有可行路径")
-
-<p>You are given an array of <strong>distinct</strong> positive integers locations where <code>locations[i]</code> represents the position of city <code>i</code>. You are also given integers <code>start</code>, <code>finish</code> and <code>fuel</code> representing the starting city, ending city, and the initial amount of fuel you have, respectively.</p>
-
-<p>At each step, if you are at city <code>i</code>, you can pick any city <code>j</code> such that <code>j != i</code> and <code>0 &lt;= j &lt; locations.length</code> and move to city <code>j</code>. Moving from city <code>i</code> to city <code>j</code> reduces the amount of fuel you have by <code>|locations[i] - locations[j]|</code>. Please notice that <code>|x|</code> denotes the absolute value of <code>x</code>.</p>
-
-<p>Notice that <code>fuel</code> <strong>cannot</strong> become negative at any point in time, and that you are <strong>allowed</strong> to visit any city more than once (including <code>start</code> and <code>finish</code>).</p>
-
-<p>Return <em>the count of all possible routes from </em><code>start</code> <em>to</em> <code>finish</code>. Since the answer may be too large, return it modulo <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> locations = [2,3,6,8,4], start = 1, finish = 3, fuel = 5
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The following are all possible routes, each uses 5 units of fuel:
-1 -&gt; 3
-1 -&gt; 2 -&gt; 3
-1 -&gt; 4 -&gt; 3
-1 -&gt; 4 -&gt; 2 -&gt; 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> locations = [4,3,1], start = 1, finish = 0, fuel = 6
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The following are all possible routes:
-1 -&gt; 0, used fuel = 1
-1 -&gt; 2 -&gt; 0, used fuel = 5
-1 -&gt; 2 -&gt; 1 -&gt; 0, used fuel = 5
-1 -&gt; 0 -&gt; 1 -&gt; 0, used fuel = 3
-1 -&gt; 0 -&gt; 1 -&gt; 0 -&gt; 1 -&gt; 0, used fuel = 5
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> locations = [5,2,1], start = 0, finish = 2, fuel = 3
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> It is impossible to get from 0 to 2 using only 3 units of fuel since the shortest route needs 4 units of fuel.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= locations.length &lt;= 100</code></li>
-	<li><code>1 &lt;= locations[i] &lt;= 10<sup>9</sup></code></li>
-	<li>All integers in <code>locations</code> are <strong>distinct</strong>.</li>
-	<li><code>0 &lt;= start, finish &lt; locations.length</code></li>
-	<li><code>1 &lt;= fuel &lt;= 200</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming to solve this problem with each state defined by the city index and fuel left.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Since the array contains distinct integers fuel will always be spent in each move and so there can be no cycles.
-</details>
diff --git a/problems/count-all-valid-pickup-and-delivery-options/README.md b/problems/count-all-valid-pickup-and-delivery-options/README.md
deleted file mode 100644
index 32cda0c3e..000000000
--- a/problems/count-all-valid-pickup-and-delivery-options/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-substrings-containing-all-three-characters "Number of Substrings Containing All Three Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-days-between-two-dates "Number of Days Between Two Dates")
-
-## [1359. Count All Valid Pickup and Delivery Options (Hard)](https://leetcode.com/problems/count-all-valid-pickup-and-delivery-options "有效的快递序列数目")
-
-<p>Given <code>n</code> orders, each order consist in pickup and delivery services.&nbsp;</p>
-
-<p>Count all valid pickup/delivery possible sequences such that delivery(i) is always after of&nbsp;pickup(i).&nbsp;</p>
-
-<p>Since the answer&nbsp;may be too large,&nbsp;return it modulo&nbsp;10^9 + 7.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Unique order (P1, D1), Delivery 1 always is after of Pickup 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> All possible orders: 
-(P1,P2,D1,D2), (P1,P2,D2,D1), (P1,D1,P2,D2), (P2,P1,D1,D2), (P2,P1,D2,D1) and (P2,D2,P1,D1).
-This is an invalid order (P1,D2,P2,D1) because Pickup 2 is after of Delivery 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 90
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use the permutation and combination theory to add one (P, D) pair each time until n pairs.
-</details>
diff --git a/problems/count-and-say/README.md b/problems/count-and-say/README.md
deleted file mode 100644
index 4ed8226bb..000000000
--- a/problems/count-and-say/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sudoku-solver "Sudoku Solver")
-　　　　　　　　　　　　　　　　
-[Next >](../combination-sum "Combination Sum")
-
-## [38. Count and Say (Medium)](https://leetcode.com/problems/count-and-say "外观数列")
-
-<p>The <strong>count-and-say</strong> sequence is a sequence of digit strings defined by the recursive formula:</p>
-
-<ul>
-	<li><code>countAndSay(1) = &quot;1&quot;</code></li>
-	<li><code>countAndSay(n)</code> is the way you would &quot;say&quot; the digit string from <code>countAndSay(n-1)</code>, which is then converted into a different digit string.</li>
-</ul>
-
-<p>To determine how you &quot;say&quot; a digit string, split it into the <strong>minimal</strong> number of groups so that each group is a contiguous section all of the <strong>same character.</strong> Then for each group, say the number of characters, then say the character. To convert the saying into a digit string, replace the counts with a number and concatenate every saying.</p>
-
-<p>For example, the saying and conversion for digit string <code>&quot;3322251&quot;</code>:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/23/countandsay.jpg" style="width: 581px; height: 172px;" />
-<p>Given a positive integer <code>n</code>, return <em>the </em><code>n<sup>th</sup></code><em> term of the <strong>count-and-say</strong> sequence</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> &quot;1&quot;
-<strong>Explanation:</strong> This is the base case.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> &quot;1211&quot;
-<strong>Explanation:</strong>
-countAndSay(1) = &quot;1&quot;
-countAndSay(2) = say &quot;1&quot; = one 1 = &quot;11&quot;
-countAndSay(3) = say &quot;11&quot; = two 1&#39;s = &quot;21&quot;
-countAndSay(4) = say &quot;21&quot; = one 2 + one 1 = &quot;12&quot; + &quot;11&quot; = &quot;1211&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 30</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Encode and Decode Strings](../encode-and-decode-strings) (Medium)
-  1. [String Compression](../string-compression) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The following are the terms from n=1 to n=10 of the count-and-say sequence:
-<pre>
- 1.     1
- 2.     11
- 3.     21
- 4.     1211
- 5.     111221 
- 6.     312211
- 7.     13112221
- 8.     1113213211
- 9.     31131211131221
-10.     13211311123113112211
-</pre>
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To generate the <i>n</i><sup>th</sup> term, just <i>count and say</i> the <i>n</i>-1<sup>th</sup> term.
-</details>
diff --git a/problems/count-and-say/count_and_say.go b/problems/count-and-say/count_and_say.go
deleted file mode 100644
index 55104effb..000000000
--- a/problems/count-and-say/count_and_say.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem38
-
-func countAndSay(n int) string {
-	r := "1"
-	for i := 1; i < n; i++ {
-		r = say(r)
-	}
-	return r
-}
-
-func say(s string) string {
-	r := ""
-	var sv rune
-	var sc byte
-	for i, v := range s {
-		if i == 0 {
-			sv = v
-			sc = '1'
-		} else {
-			if v == rune(s[i-1]) {
-				sc++
-			} else {
-				r += string(sc) + string(sv)
-				sv = v
-				sc = '1'
-			}
-		}
-	}
-	if sc > '0' {
-		r += string(sc) + string(sv)
-	}
-	return r
-}
diff --git a/problems/count-and-say/count_and_say_test.go b/problems/count-and-say/count_and_say_test.go
deleted file mode 100644
index 95704ed75..000000000
--- a/problems/count-and-say/count_and_say_test.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem38
-
-import "testing"
-
-func TestCountAndSay(t *testing.T) {
-	tests := map[int]string{
-		1: "1",
-		3: "21",
-		5: "111221",
-		7: "13112221",
-		9: "31131211131221",
-	}
-
-	for in, want := range tests {
-		got := countAndSay(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/count-apples-and-oranges/README.md b/problems/count-apples-and-oranges/README.md
deleted file mode 100644
index beb6557bc..000000000
--- a/problems/count-apples-and-oranges/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-special-evenly-spaced-elements-in-array "Sum Of Special Evenly-Spaced Elements In Array")
-　　　　　　　　　　　　　　　　
-[Next >](../calculate-money-in-leetcode-bank "Calculate Money in Leetcode Bank")
-
-## [1715. Count Apples and Oranges (Medium)](https://leetcode.com/problems/count-apples-and-oranges "苹果和橘子的个数")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/count-apples-and-oranges/mysql_schemas.sql b/problems/count-apples-and-oranges/mysql_schemas.sql
deleted file mode 100644
index 89d31e15c..000000000
--- a/problems/count-apples-and-oranges/mysql_schemas.sql
+++ /dev/null
@@ -1,16 +0,0 @@
-Create table If Not Exists Boxes (box_id int, chest_id int, apple_count int, orange_count int);
-Create table If Not Exists Chests (chest_id int, apple_count int, orange_count int);
-Truncate table Boxes;
-insert into Boxes (box_id, chest_id, apple_count, orange_count) values ('2', 'None', '6', '15');
-insert into Boxes (box_id, chest_id, apple_count, orange_count) values ('18', '14', '4', '15');
-insert into Boxes (box_id, chest_id, apple_count, orange_count) values ('19', '3', '8', '4');
-insert into Boxes (box_id, chest_id, apple_count, orange_count) values ('12', '2', '19', '20');
-insert into Boxes (box_id, chest_id, apple_count, orange_count) values ('20', '6', '12', '9');
-insert into Boxes (box_id, chest_id, apple_count, orange_count) values ('8', '6', '9', '9');
-insert into Boxes (box_id, chest_id, apple_count, orange_count) values ('3', '14', '16', '7');
-Truncate table Chests;
-insert into Chests (chest_id, apple_count, orange_count) values ('6', '5', '6');
-insert into Chests (chest_id, apple_count, orange_count) values ('14', '20', '10');
-insert into Chests (chest_id, apple_count, orange_count) values ('2', '8', '8');
-insert into Chests (chest_id, apple_count, orange_count) values ('3', '19', '4');
-insert into Chests (chest_id, apple_count, orange_count) values ('16', '19', '19');
diff --git a/problems/count-binary-substrings/README.md b/problems/count-binary-substrings/README.md
deleted file mode 100644
index de93a8d21..000000000
--- a/problems/count-binary-substrings/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-area-of-island "Max Area of Island")
-　　　　　　　　　　　　　　　　
-[Next >](../degree-of-an-array "Degree of an Array")
-
-## [696. Count Binary Substrings (Easy)](https://leetcode.com/problems/count-binary-substrings "计数二进制子串")
-
-<p>Give a binary string <code>s</code>, return the number of non-empty substrings that have the same number of <code>0</code>&#39;s and <code>1</code>&#39;s, and all the <code>0</code>&#39;s and all the <code>1</code>&#39;s in these substrings are grouped consecutively.</p>
-
-<p>Substrings that occur multiple times are counted the number of times they occur.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;00110011&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> There are 6 substrings that have equal number of consecutive 1&#39;s and 0&#39;s: &quot;0011&quot;, &quot;01&quot;, &quot;1100&quot;, &quot;10&quot;, &quot;0011&quot;, and &quot;01&quot;.
-Notice that some of these substrings repeat and are counted the number of times they occur.
-Also, &quot;00110011&quot; is not a valid substring because all the 0&#39;s (and 1&#39;s) are not grouped together.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;10101&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are 4 substrings: &quot;10&quot;, &quot;01&quot;, &quot;10&quot;, &quot;01&quot; that have equal number of consecutive 1&#39;s and 0&#39;s.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Encode and Decode Strings](../encode-and-decode-strings) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many valid binary substrings exist in "000111", and how many in "11100"?  What about "00011100"?
-</details>
diff --git a/problems/count-binary-substrings/count_binary_substrings.go b/problems/count-binary-substrings/count_binary_substrings.go
deleted file mode 100644
index 33be90891..000000000
--- a/problems/count-binary-substrings/count_binary_substrings.go
+++ /dev/null
@@ -1,22 +0,0 @@
-package problem696
-
-func countBinarySubstrings(s string) int {
-	ans, pre, cur, l := 0, 0, 1, len(s)
-	for i := 1; i < l; i++ {
-		if s[i] != s[i-1] {
-			ans += min(pre, cur)
-			pre = cur
-			cur = 1
-		} else {
-			cur++
-		}
-	}
-	return ans + min(pre, cur)
-}
-
-func min(x, y int) int {
-	if x < y {
-		return x
-	}
-	return y
-}
diff --git a/problems/count-binary-substrings/count_binary_substrings_test.go b/problems/count-binary-substrings/count_binary_substrings_test.go
deleted file mode 100644
index 606c5a873..000000000
--- a/problems/count-binary-substrings/count_binary_substrings_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem696
-
-import "testing"
-
-type testType struct {
-	in   string
-	want int
-}
-
-func TestCountBinarySubstrings(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "00110011",
-			want: 6,
-		},
-		{
-			in:   "10101",
-			want: 4,
-		},
-	}
-	for _, tt := range tests {
-		got := countBinarySubstrings(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/count-common-words-with-one-occurrence/README.md b/problems/count-common-words-with-one-occurrence/README.md
deleted file mode 100644
index 776b6f8bc..000000000
--- a/problems/count-common-words-with-one-occurrence/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../drop-type-1-orders-for-customers-with-type-0-orders "Drop Type 1 Orders for Customers With Type 0 Orders")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-buckets-required-to-collect-rainwater-from-houses "Minimum Number of Buckets Required to Collect Rainwater from Houses")
-
-## [2085. Count Common Words With One Occurrence (Easy)](https://leetcode.com/problems/count-common-words-with-one-occurrence "统计出现过一次的公共字符串")
-
-<p>Given two string arrays <code>words1</code> and <code>words2</code>, return <em>the number of strings that appear <strong>exactly once</strong> in <b>each</b>&nbsp;of the two arrays.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words1 = [&quot;leetcode&quot;,&quot;is&quot;,&quot;amazing&quot;,&quot;as&quot;,&quot;is&quot;], words2 = [&quot;amazing&quot;,&quot;leetcode&quot;,&quot;is&quot;]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-- &quot;leetcode&quot; appears exactly once in each of the two arrays. We count this string.
-- &quot;amazing&quot; appears exactly once in each of the two arrays. We count this string.
-- &quot;is&quot; appears in each of the two arrays, but there are 2 occurrences of it in words1. We do not count this string.
-- &quot;as&quot; appears once in words1, but does not appear in words2. We do not count this string.
-Thus, there are 2 strings that appear exactly once in each of the two arrays.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words1 = [&quot;b&quot;,&quot;bb&quot;,&quot;bbb&quot;], words2 = [&quot;a&quot;,&quot;aa&quot;,&quot;aaa&quot;]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no strings that appear in each of the two arrays.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words1 = [&quot;a&quot;,&quot;ab&quot;], words2 = [&quot;a&quot;,&quot;a&quot;,&quot;a&quot;,&quot;ab&quot;]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only string that appears exactly once in each of the two arrays is &quot;ab&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words1.length, words2.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= words1[i].length, words2[j].length &lt;= 30</code></li>
-	<li><code>words1[i]</code> and <code>words2[j]</code> consists only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could you try every word?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Could you use a hash map to achieve a good complexity?
-</details>
diff --git a/problems/count-complete-tree-nodes/README.md b/problems/count-complete-tree-nodes/README.md
deleted file mode 100644
index 3770c14e4..000000000
--- a/problems/count-complete-tree-nodes/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximal-square "Maximal Square")
-　　　　　　　　　　　　　　　　
-[Next >](../rectangle-area "Rectangle Area")
-
-## [222. Count Complete Tree Nodes (Medium)](https://leetcode.com/problems/count-complete-tree-nodes "完全二叉树的节点个数")
-
-<p>Given the <code>root</code> of a <strong>complete</strong> binary tree, return the number of the nodes in the tree.</p>
-
-<p>According to <strong><a href="http://en.wikipedia.org/wiki/Binary_tree#Types_of_binary_trees" target="_blank">Wikipedia</a></strong>, every level, except possibly the last, is completely filled in a complete binary tree, and all nodes in the last level are as far left as possible. It can have between <code>1</code> and <code>2<sup>h</sup></code> nodes inclusive at the last level <code>h</code>.</p>
-
-<p>Design an algorithm that runs in less than&nbsp;<code data-stringify-type="code">O(n)</code>&nbsp;time complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/14/complete.jpg" style="width: 372px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,6]
-<strong>Output:</strong> 6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 5 * 10<sup>4</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 5 * 10<sup>4</sup></code></li>
-	<li>The tree is guaranteed to be <strong>complete</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Closest Binary Search Tree Value](../closest-binary-search-tree-value) (Easy)
diff --git a/problems/count-complete-tree-nodes/count_complete_tree_nodes.go b/problems/count-complete-tree-nodes/count_complete_tree_nodes.go
deleted file mode 100644
index dcca2981d..000000000
--- a/problems/count-complete-tree-nodes/count_complete_tree_nodes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem222
diff --git a/problems/count-complete-tree-nodes/count_complete_tree_nodes_test.go b/problems/count-complete-tree-nodes/count_complete_tree_nodes_test.go
deleted file mode 100644
index dcca2981d..000000000
--- a/problems/count-complete-tree-nodes/count_complete_tree_nodes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem222
diff --git a/problems/count-different-palindromic-subsequences/README.md b/problems/count-different-palindromic-subsequences/README.md
deleted file mode 100644
index c0d8334f8..000000000
--- a/problems/count-different-palindromic-subsequences/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../my-calendar-i "My Calendar I")
-　　　　　　　　　　　　　　　　
-[Next >](../my-calendar-ii "My Calendar II")
-
-## [730. Count Different Palindromic Subsequences (Hard)](https://leetcode.com/problems/count-different-palindromic-subsequences "统计不同回文子序列")
-
-<p>Given a string s, return <em>the number of different non-empty palindromic subsequences in</em> <code>s</code>. Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>A subsequence of a string is obtained by deleting zero or more characters from the string.</p>
-
-<p>A sequence is palindromic if it is equal to the sequence reversed.</p>
-
-<p>Two sequences <code>a<sub>1</sub>, a<sub>2</sub>, ...</code> and <code>b<sub>1</sub>, b<sub>2</sub>, ...</code> are different if there is some <code>i</code> for which <code>a<sub>i</sub> != b<sub>i</sub></code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bccb&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The 6 different non-empty palindromic subsequences are &#39;b&#39;, &#39;c&#39;, &#39;bb&#39;, &#39;cc&#39;, &#39;bcb&#39;, &#39;bccb&#39;.
-Note that &#39;bcb&#39; is counted only once, even though it occurs twice.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcdabcdabcdabcdabcdabcdabcdabcddcbadcbadcbadcbadcbadcbadcbadcba&quot;
-<strong>Output:</strong> 104860361
-<strong>Explanation:</strong> There are 3104860382 different non-empty palindromic subsequences, which is 104860361 modulo 10<sup>9</sup> + 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s[i]</code> is either <code>&#39;a&#39;</code>, <code>&#39;b&#39;</code>, <code>&#39;c&#39;</code>, or <code>&#39;d&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Longest Palindromic Subsequence](../longest-palindromic-subsequence) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let dp(i, j) be the answer for the string T = S[i:j+1] including the empty sequence. The answer is the number of unique characters in T, plus palindromes of the form "a_a", "b_b", "c_c", and "d_d", where "_" represents zero or more characters.
-</details>
diff --git a/problems/count-different-palindromic-subsequences/count_different_palindromic_subsequences.go b/problems/count-different-palindromic-subsequences/count_different_palindromic_subsequences.go
deleted file mode 100644
index 1ef294407..000000000
--- a/problems/count-different-palindromic-subsequences/count_different_palindromic_subsequences.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem730
diff --git a/problems/count-different-palindromic-subsequences/count_different_palindromic_subsequences_test.go b/problems/count-different-palindromic-subsequences/count_different_palindromic_subsequences_test.go
deleted file mode 100644
index 1ef294407..000000000
--- a/problems/count-different-palindromic-subsequences/count_different_palindromic_subsequences_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem730
diff --git a/problems/count-elements-with-strictly-smaller-and-greater-elements/README.md b/problems/count-elements-with-strictly-smaller-and-greater-elements/README.md
deleted file mode 100644
index 199267f0b..000000000
--- a/problems/count-elements-with-strictly-smaller-and-greater-elements/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-divide-a-long-corridor "Number of Ways to Divide a Long Corridor")
-　　　　　　　　　　　　　　　　
-[Next >](../rearrange-array-elements-by-sign "Rearrange Array Elements by Sign")
-
-## [2148. Count Elements With Strictly Smaller and Greater Elements  (Easy)](https://leetcode.com/problems/count-elements-with-strictly-smaller-and-greater-elements "元素计数")
-
-<p>Given an integer array <code>nums</code>, return <em>the number of elements that have <strong>both</strong> a strictly smaller and a strictly greater element appear in </em><code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [11,7,2,15]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The element 7 has the element 2 strictly smaller than it and the element 11 strictly greater than it.
-Element 11 has element 7 strictly smaller than it and element 15 strictly greater than it.
-In total there are 2 elements having both a strictly smaller and a strictly greater element appear in <code>nums</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-3,3,3,90]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The element 3 has the element -3 strictly smaller than it and the element 90 strictly greater than it.
-Since there are two elements with the value 3, in total there are 2 elements having both a strictly smaller and a strictly greater element appear in <code>nums</code>.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-All the elements in the array should be counted except for the minimum and maximum elements.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the array has n elements, the answer will be n - count(min(nums)) - count(max(nums))
-</details>
-
-<details>
-<summary>Hint 3</summary>
-This formula will not work in case the array has all the elements equal, why?
-</details>
diff --git a/problems/count-fertile-pyramids-in-a-land/README.md b/problems/count-fertile-pyramids-in-a-land/README.md
deleted file mode 100644
index 9e438e6a1..000000000
--- a/problems/count-fertile-pyramids-in-a-land/README.md
+++ /dev/null
@@ -1,99 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-homecoming-of-a-robot-in-a-grid "Minimum Cost Homecoming of a Robot in a Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../find-target-indices-after-sorting-array "Find Target Indices After Sorting Array")
-
-## [2088. Count Fertile Pyramids in a Land (Hard)](https://leetcode.com/problems/count-fertile-pyramids-in-a-land "统计农场中肥沃金字塔的数目")
-
-<p>A farmer has a <strong>rectangular grid</strong> of land with <code>m</code> rows and <code>n</code> columns that can be divided into unit cells. Each cell is either <strong>fertile</strong> (represented by a <code>1</code>) or <strong>barren</strong> (represented by a <code>0</code>). All cells outside the grid are considered barren.</p>
-
-<p>A <strong>pyramidal plot</strong> of land can be defined as a set of cells with the following criteria:</p>
-
-<ol>
-	<li>The number of cells in the set has to be <strong>greater than </strong><code>1</code> and all cells must be <strong>fertile</strong>.</li>
-	<li>The <strong>apex</strong> of a pyramid is the <strong>topmost</strong> cell of the pyramid. The <strong>height</strong> of a pyramid is the number of rows it covers. Let <code>(r, c)</code> be the apex of the pyramid, and its height be <code>h</code>. Then, the plot comprises of cells <code>(i, j)</code> where <code>r &lt;= i &lt;= r + h - 1</code> <strong>and</strong> <code>c - (i - r) &lt;= j &lt;= c + (i - r)</code>.</li>
-</ol>
-
-<p>An <strong>inverse pyramidal plot</strong> of land can be defined as a set of cells with similar criteria:</p>
-
-<ol>
-	<li>The number of cells in the set has to be <strong>greater than </strong><code>1</code> and all cells must be <strong>fertile</strong>.</li>
-	<li>The <strong>apex</strong> of an inverse pyramid is the <strong>bottommost</strong> cell of the inverse pyramid. The <strong>height</strong> of an inverse pyramid is the number of rows it covers. Let <code>(r, c)</code> be the apex of the pyramid, and its height be <code>h</code>. Then, the plot comprises of cells <code>(i, j)</code> where <code>r - h + 1 &lt;= i &lt;= r</code> <strong>and</strong> <code>c - (r - i) &lt;= j &lt;= c + (r - i)</code>.</li>
-</ol>
-
-<p>Some examples of valid and invalid pyramidal (and inverse pyramidal) plots are shown below. Black cells indicate fertile cells.</p>
-<img src="https://assets.leetcode.com/uploads/2021/11/08/image.png" style="width: 700px; height: 156px;" />
-<p>Given a <strong>0-indexed</strong> <code>m x n</code> binary matrix <code>grid</code> representing the farmland, return <em>the <strong>total number</strong> of pyramidal and inverse pyramidal plots that can be found in</em> <code>grid</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/22/1.JPG" style="width: 575px; height: 109px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1,1,0],[1,1,1,1]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The 2 possible pyramidal plots are shown in blue and red respectively.
-There are no inverse pyramidal plots in this grid. 
-Hence total number of pyramidal and inverse pyramidal plots is 2 + 0 = 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/22/2.JPG" style="width: 502px; height: 120px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,1,1],[1,1,1]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The pyramidal plot is shown in blue, and the inverse pyramidal plot is shown in red. 
-Hence the total number of plots is 1 + 1 = 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/22/3.JPG" style="width: 676px; height: 148px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,1,1,1,0],[1,1,1,1,1],[1,1,1,1,1],[0,1,0,0,1]]
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> There are 7 pyramidal plots, 3 of which are shown in the 2nd and 3rd figures.
-There are 6 inverse pyramidal plots, 2 of which are shown in the last figure.
-The total number of plots is 7 + 6 = 13.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 1000</code></li>
-	<li><code>1 &lt;= m * n &lt;= 10<sup>5</sup></code></li>
-	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think about how dynamic programming can help solve the problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For any fixed cell (r, c), can you calculate the maximum height of the pyramid for which it is the apex? Let us denote this value as dp[r][c].
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How will the values at dp[r+1][c-1] and dp[r+1][c+1] help in determining the value at dp[r][c]?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For the cell (r, c), is there a relation between the number of pyramids for which it serves as the apex and dp[r][c]? How does it help in calculating the answer?
-</details>
diff --git a/problems/count-good-meals/README.md b/problems/count-good-meals/README.md
deleted file mode 100644
index 472223138..000000000
--- a/problems/count-good-meals/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-units-on-a-truck "Maximum Units on a Truck")
-　　　　　　　　　　　　　　　　
-[Next >](../ways-to-split-array-into-three-subarrays "Ways to Split Array Into Three Subarrays")
-
-## [1711. Count Good Meals (Medium)](https://leetcode.com/problems/count-good-meals "大餐计数")
-
-<p>A <strong>good meal</strong> is a meal that contains <strong>exactly two different food items</strong> with a sum of deliciousness equal to a power of two.</p>
-
-<p>You can pick <strong>any</strong> two different foods to make a good meal.</p>
-
-<p>Given an array of integers <code>deliciousness</code> where <code>deliciousness[i]</code> is the deliciousness of the <code>i<sup>​​​​​​th</sup>​​​​</code>​​​​ item of food, return <em>the number of different <strong>good meals</strong> you can make from this list modulo</em> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>Note that items with different indices are considered different even if they have the same deliciousness value.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> deliciousness = [1,3,5,7,9]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>The good meals are (1,3), (1,7), (3,5) and, (7,9).
-Their respective sums are 4, 8, 8, and 16, all of which are powers of 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> deliciousness = [1,1,1,3,3,3,7]
-<strong>Output:</strong> 15
-<strong>Explanation: </strong>The good meals are (1,1) with 3 ways, (1,3) with 9 ways, and (1,7) with 3 ways.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= deliciousness.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= deliciousness[i] &lt;= 2<sup>20</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [Two Sum](../two-sum) (Easy)
-  1. [Max Number of K-Sum Pairs](../max-number-of-k-sum-pairs) (Medium)
-  1. [Find All Possible Recipes from Given Supplies](../find-all-possible-recipes-from-given-supplies) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that the number of powers of 2 is at most 21 so this turns the problem to a classic find the number of pairs that sum to a certain value but for 21 values
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You need to use something fasters than the NlogN approach since there is already the log of iterating over the powers so one idea is two pointers
-</details>
diff --git a/problems/count-good-nodes-in-binary-tree/README.md b/problems/count-good-nodes-in-binary-tree/README.md
deleted file mode 100644
index 4a8baa459..000000000
--- a/problems/count-good-nodes-in-binary-tree/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../simplified-fractions "Simplified Fractions")
-　　　　　　　　　　　　　　　　
-[Next >](../form-largest-integer-with-digits-that-add-up-to-target "Form Largest Integer With Digits That Add up to Target")
-
-## [1448. Count Good Nodes in Binary Tree (Medium)](https://leetcode.com/problems/count-good-nodes-in-binary-tree "统计二叉树中好节点的数目")
-
-<p>Given a binary tree <code>root</code>, a node <em>X</em> in the tree is named&nbsp;<strong>good</strong> if in the path from root to <em>X</em> there are no nodes with a value <em>greater than</em> X.</p>
-
-<p>Return the number of <strong>good</strong> nodes in the binary tree.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/04/02/test_sample_1.png" style="width: 263px; height: 156px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> root = [3,1,4,3,null,1,5]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Nodes in blue are <strong>good</strong>.
-Root Node (3) is always a good node.
-Node 4 -&gt; (3,4) is the maximum value in the path starting from the root.
-Node 5 -&gt; (3,4,5) is the maximum value in the path
-Node 3 -&gt; (3,1,3) is the maximum value in the path.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/04/02/test_sample_2.png" style="width: 157px; height: 161px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> root = [3,3,null,4,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Node 2 -&gt; (3, 3, 2) is not good, because &quot;3&quot; is higher than it.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Root is considered as <strong>good</strong>.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the binary tree is in the range&nbsp;<code>[1, 10^5]</code>.</li>
-	<li>Each node&#39;s value is between <code>[-10^4, 10^4]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use DFS (Depth First Search) to traverse the tree, and constantly keep track of the current path maximum.
-</details>
diff --git a/problems/count-good-numbers/README.md b/problems/count-good-numbers/README.md
deleted file mode 100644
index ab7e822a8..000000000
--- a/problems/count-good-numbers/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../eliminate-maximum-number-of-monsters "Eliminate Maximum Number of Monsters")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-common-subpath "Longest Common Subpath")
-
-## [1922. Count Good Numbers (Medium)](https://leetcode.com/problems/count-good-numbers "统计好数字的数目")
-
-<p>A digit string is <strong>good</strong> if the digits <strong>(0-indexed)</strong> at <strong>even</strong> indices are <strong>even</strong> and the digits at <strong>odd</strong> indices are <strong>prime</strong> (<code>2</code>, <code>3</code>, <code>5</code>, or <code>7</code>).</p>
-
-<ul>
-	<li>For example, <code>&quot;2582&quot;</code> is good because the digits (<code>2</code> and <code>8</code>) at even positions are even and the digits (<code>5</code> and <code>2</code>) at odd positions are prime. However, <code>&quot;3245&quot;</code> is <strong>not</strong> good because <code>3</code> is at an even index but is not even.</li>
-</ul>
-
-<p>Given an integer <code>n</code>, return <em>the <strong>total</strong> number of good digit strings of length </em><code>n</code>. Since the answer may be large, <strong>return it modulo </strong><code>10<sup>9</sup> + 7</code>.</p>
-
-<p>A <strong>digit string</strong> is a string consisting of digits <code>0</code> through <code>9</code> that may contain leading zeros.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The good numbers of length 1 are &quot;0&quot;, &quot;2&quot;, &quot;4&quot;, &quot;6&quot;, &quot;8&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 400
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 50
-<strong>Output:</strong> 564908303
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>15</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is there a formula we can use to find the count of all the good numbers?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Exponentiation can be done very fast if we looked at the binary bits of n.
-</details>
diff --git a/problems/count-good-triplets/README.md b/problems/count-good-triplets/README.md
deleted file mode 100644
index 10a302420..000000000
--- a/problems/count-good-triplets/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-index-of-the-large-integer "Find the Index of the Large Integer")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-winner-of-an-array-game "Find the Winner of an Array Game")
-
-## [1534. Count Good Triplets (Easy)](https://leetcode.com/problems/count-good-triplets "统计好三元组")
-
-<p>Given an array of integers <code>arr</code>, and three integers&nbsp;<code>a</code>,&nbsp;<code>b</code>&nbsp;and&nbsp;<code>c</code>. You need to find the number of good triplets.</p>
-
-<p>A triplet <code>(arr[i], arr[j], arr[k])</code>&nbsp;is <strong>good</strong> if the following conditions are true:</p>
-
-<ul>
-	<li><code>0 &lt;= i &lt; j &lt; k &lt;&nbsp;arr.length</code></li>
-	<li><code>|arr[i] - arr[j]| &lt;= a</code></li>
-	<li><code>|arr[j] - arr[k]| &lt;= b</code></li>
-	<li><code>|arr[i] - arr[k]| &lt;= c</code></li>
-</ul>
-
-<p>Where <code>|x|</code> denotes the absolute value of <code>x</code>.</p>
-
-<p>Return<em> the number of good triplets</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,0,1,1,9,7], a = 7, b = 2, c = 3
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>&nbsp;There are 4 good triplets: [(3,0,1), (3,0,1), (3,1,1), (0,1,1)].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,1,2,2,3], a = 0, b = 0, c = 1
-<strong>Output:</strong> 0
-<strong>Explanation: </strong>No triplet satisfies all conditions.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= arr.length &lt;= 100</code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 1000</code></li>
-	<li><code>0 &lt;= a, b, c &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Notice that the constraints are small enough for a brute force solution to pass.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop through all triplets, and count the ones that are good.
-</details>
diff --git a/problems/count-items-matching-a-rule/README.md b/problems/count-items-matching-a-rule/README.md
deleted file mode 100644
index 0da1a676a..000000000
--- a/problems/count-items-matching-a-rule/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-features-by-popularity "Sort Features by Popularity")
-　　　　　　　　　　　　　　　　
-[Next >](../closest-dessert-cost "Closest Dessert Cost")
-
-## [1773. Count Items Matching a Rule (Easy)](https://leetcode.com/problems/count-items-matching-a-rule "统计匹配检索规则的物品数量")
-
-<p>You are given an array <code>items</code>, where each <code>items[i] = [type<sub>i</sub>, color<sub>i</sub>, name<sub>i</sub>]</code> describes the type, color, and name of the <code>i<sup>th</sup></code> item. You are also given a rule represented by two strings, <code>ruleKey</code> and <code>ruleValue</code>.</p>
-
-<p>The <code>i<sup>th</sup></code> item is said to match the rule if <strong>one</strong> of the following is true:</p>
-
-<ul>
-	<li><code>ruleKey == &quot;type&quot;</code> and <code>ruleValue == type<sub>i</sub></code>.</li>
-	<li><code>ruleKey == &quot;color&quot;</code> and <code>ruleValue == color<sub>i</sub></code>.</li>
-	<li><code>ruleKey == &quot;name&quot;</code> and <code>ruleValue == name<sub>i</sub></code>.</li>
-</ul>
-
-<p>Return <em>the number of items that match the given rule</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> items = [[&quot;phone&quot;,&quot;blue&quot;,&quot;pixel&quot;],[&quot;computer&quot;,&quot;silver&quot;,&quot;lenovo&quot;],[&quot;phone&quot;,&quot;gold&quot;,&quot;iphone&quot;]], ruleKey = &quot;color&quot;, ruleValue = &quot;silver&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There is only one item matching the given rule, which is [&quot;computer&quot;,&quot;silver&quot;,&quot;lenovo&quot;].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> items = [[&quot;phone&quot;,&quot;blue&quot;,&quot;pixel&quot;],[&quot;computer&quot;,&quot;silver&quot;,&quot;phone&quot;],[&quot;phone&quot;,&quot;gold&quot;,&quot;iphone&quot;]], ruleKey = &quot;type&quot;, ruleValue = &quot;phone&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are only two items matching the given rule, which are [&quot;phone&quot;,&quot;blue&quot;,&quot;pixel&quot;] and [&quot;phone&quot;,&quot;gold&quot;,&quot;iphone&quot;]. Note that the item [&quot;computer&quot;,&quot;silver&quot;,&quot;phone&quot;] does not match.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= items.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= type<sub>i</sub>.length, color<sub>i</sub>.length, name<sub>i</sub>.length, ruleValue.length &lt;= 10</code></li>
-	<li><code>ruleKey</code> is equal to either <code>&quot;type&quot;</code>, <code>&quot;color&quot;</code>, or <code>&quot;name&quot;</code>.</li>
-	<li>All strings consist only of lowercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate on each item, and check if each one matches the rule according to the statement.
-</details>
diff --git a/problems/count-largest-group/README.md b/problems/count-largest-group/README.md
deleted file mode 100644
index 38160b260..000000000
--- a/problems/count-largest-group/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../customers-who-bought-products-a-and-b-but-not-c "Customers Who Bought Products A and B but Not C")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-k-palindrome-strings "Construct K Palindrome Strings")
-
-## [1399. Count Largest Group (Easy)](https://leetcode.com/problems/count-largest-group "统计最大组的数目")
-
-<p>You are given an integer <code>n</code>.</p>
-
-<p>Each number from <code>1</code> to <code>n</code> is grouped according to the sum of its digits.</p>
-
-<p>Return <em>the number of groups that have the largest size</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 13
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are 9 groups in total, they are grouped according sum of its digits of numbers from 1 to 13:
-[1,10], [2,11], [3,12], [4,13], [5], [6], [7], [8], [9].
-There are 4 groups with largest size.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are 2 groups [1], [2] of size 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the digit sum for each integer in the range and find out the largest groups.
-</details>
diff --git a/problems/count-largest-group/count_largest_group.go b/problems/count-largest-group/count_largest_group.go
deleted file mode 100644
index ae012a3f8..000000000
--- a/problems/count-largest-group/count_largest_group.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem1399
-
-func countLargestGroup(n int) int {
-	group := make(map[int]int)
-	for i := 1; i <= n; i++ {
-		s := 0
-		for x := i; x > 0; x /= 10 {
-			s += x % 10
-		}
-		group[s]++
-	}
-	ans, max := 0, 0
-	for _, v := range group {
-		if v == max {
-			ans++
-		} else if v > max {
-			ans, max = 1, v
-		}
-	}
-	return ans
-}
diff --git a/problems/count-largest-group/count_largest_group_test.go b/problems/count-largest-group/count_largest_group_test.go
deleted file mode 100644
index 56bb1705c..000000000
--- a/problems/count-largest-group/count_largest_group_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1399
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestCountLargestGroup(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   13,
-			want: 4,
-		},
-		{
-			in:   2,
-			want: 2,
-		},
-		{
-			in:   15,
-			want: 6,
-		},
-		{
-			in:   24,
-			want: 5,
-		},
-	}
-	for _, tt := range tests {
-		got := countLargestGroup(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/count-negative-numbers-in-a-sorted-matrix/README.md b/problems/count-negative-numbers-in-a-sorted-matrix/README.md
deleted file mode 100644
index 7bfda52f4..000000000
--- a/problems/count-negative-numbers-in-a-sorted-matrix/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../students-with-invalid-departments "Students With Invalid Departments")
-　　　　　　　　　　　　　　　　
-[Next >](../product-of-the-last-k-numbers "Product of the Last K Numbers")
-
-## [1351. Count Negative Numbers in a Sorted Matrix (Easy)](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix "统计有序矩阵中的负数")
-
-<p>Given a <code>m x n</code> matrix <code>grid</code> which is sorted in non-increasing order both row-wise and column-wise, return <em>the number of <strong>negative</strong> numbers in</em> <code>grid</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[4,3,2,-1],[3,2,1,-1],[1,1,-1,-2],[-1,-1,-2,-3]]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> There are 8 negatives number in the matrix.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[3,2],[1,0]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li><code>-100 &lt;= grid[i][j] &lt;= 100</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you find an <code>O(n + m)</code> solution?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use binary search for optimization or simply brute force.
-</details>
diff --git a/problems/count-nice-pairs-in-an-array/README.md b/problems/count-nice-pairs-in-an-array/README.md
deleted file mode 100644
index 5cc54e815..000000000
--- a/problems/count-nice-pairs-in-an-array/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sentence-similarity-iii "Sentence Similarity III")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-groups-getting-fresh-donuts "Maximum Number of Groups Getting Fresh Donuts")
-
-## [1814. Count Nice Pairs in an Array (Medium)](https://leetcode.com/problems/count-nice-pairs-in-an-array "统计一个数组中好对子的数目")
-
-<p>You are given an array <code>nums</code> that consists of non-negative integers. Let us define <code>rev(x)</code> as the reverse of the non-negative integer <code>x</code>. For example, <code>rev(123) = 321</code>, and <code>rev(120) = 21</code>. A pair of indices <code>(i, j)</code> is <strong>nice</strong> if it satisfies all of the following conditions:</p>
-
-<ul>
-	<li><code>0 &lt;= i &lt; j &lt; nums.length</code></li>
-	<li><code>nums[i] + rev(nums[j]) == nums[j] + rev(nums[i])</code></li>
-</ul>
-
-<p>Return <em>the number of nice pairs of indices</em>. Since that number can be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [42,11,1,97]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The two pairs are:
- - (0,3) : 42 + rev(97) = 42 + 79 = 121, 97 + rev(42) = 97 + 24 = 121.
- - (1,2) : 11 + rev(1) = 11 + 1 = 12, 1 + rev(11) = 1 + 11 = 12.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [13,10,35,24,76]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Number of Pairs of Interchangeable Rectangles](../number-of-pairs-of-interchangeable-rectangles) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The condition can be rearranged to (nums[i] - rev(nums[i])) == (nums[j] - rev(nums[j])).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Transform each nums[i] into (nums[i] - rev(nums[i])). Then, count the number of (i, j) pairs that have equal values.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Keep a map storing the frequencies of values that you have seen so far. For each i, check if nums[i] is in the map. If it is, then add that count to the overall count. Then, increment the frequency of nums[i].
-</details>
diff --git a/problems/count-nodes-equal-to-sum-of-descendants/README.md b/problems/count-nodes-equal-to-sum-of-descendants/README.md
deleted file mode 100644
index 3008e7d1d..000000000
--- a/problems/count-nodes-equal-to-sum-of-descendants/README.md
+++ /dev/null
@@ -1,25 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../first-and-last-call-on-the-same-day "First and Last Call On the Same Day")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-time-to-type-word-using-special-typewriter "Minimum Time to Type Word Using Special Typewriter")
-
-## [1973. Count Nodes Equal to Sum of Descendants (Medium)](https://leetcode.com/problems/count-nodes-equal-to-sum-of-descendants "值等于子节点值之和的节点数量")
-
-
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we reuse previously calculated information?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we calculate the sum of the current subtree using the sum of the child's subtree?
-</details>
diff --git a/problems/count-nodes-with-the-highest-score/README.md b/problems/count-nodes-with-the-highest-score/README.md
deleted file mode 100644
index 1bab0218c..000000000
--- a/problems/count-nodes-with-the-highest-score/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../next-greater-numerically-balanced-number "Next Greater Numerically Balanced Number")
-　　　　　　　　　　　　　　　　
-[Next >](../parallel-courses-iii "Parallel Courses III")
-
-## [2049. Count Nodes With the Highest Score (Medium)](https://leetcode.com/problems/count-nodes-with-the-highest-score "统计最高分的节点数目")
-
-<p>There is a <strong>binary</strong> tree rooted at <code>0</code> consisting of <code>n</code> nodes. The nodes are labeled from <code>0</code> to <code>n - 1</code>. You are given a <strong>0-indexed</strong> integer array <code>parents</code> representing the tree, where <code>parents[i]</code> is the parent of node <code>i</code>. Since node <code>0</code> is the root, <code>parents[0] == -1</code>.</p>
-
-<p>Each node has a <strong>score</strong>. To find the score of a node, consider if the node and the edges connected to it were <strong>removed</strong>. The tree would become one or more <strong>non-empty</strong> subtrees. The <strong>size</strong> of a subtree is the number of the nodes in it. The <strong>score</strong> of the node is the <strong>product of the sizes</strong> of all those subtrees.</p>
-
-<p>Return <em>the <strong>number</strong> of nodes that have the <strong>highest score</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="example-1" src="https://assets.leetcode.com/uploads/2021/10/03/example-1.png" style="width: 604px; height: 266px;" />
-<pre>
-<strong>Input:</strong> parents = [-1,2,0,2,0]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-- The score of node 0 is: 3 * 1 = 3
-- The score of node 1 is: 4 = 4
-- The score of node 2 is: 1 * 1 * 2 = 2
-- The score of node 3 is: 4 = 4
-- The score of node 4 is: 4 = 4
-The highest score is 4, and three nodes (node 1, node 3, and node 4) have the highest score.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="example-2" src="https://assets.leetcode.com/uploads/2021/10/03/example-2.png" style="width: 95px; height: 143px;" />
-<pre>
-<strong>Input:</strong> parents = [-1,2,0]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-- The score of node 0 is: 2 = 2
-- The score of node 1 is: 2 = 2
-- The score of node 2 is: 1 * 1 = 1
-The highest score is 2, and two nodes (node 0 and node 1) have the highest score.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == parents.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>parents[0] == -1</code></li>
-	<li><code>0 &lt;= parents[i] &lt;= n - 1</code> for <code>i != 0</code></li>
-	<li><code>parents</code> represents a valid binary tree.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each node, you need to find the sizes of the subtrees rooted in each of its children. Maybe DFS?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How to determine the number of nodes in the rest of the tree? Can you subtract the size of the subtree rooted at the node from the total number of nodes of the tree?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use these values to compute the score of the node. Track the maximum score, and how many nodes achieve such score.
-</details>
diff --git a/problems/count-number-of-homogenous-substrings/README.md b/problems/count-number-of-homogenous-substrings/README.md
deleted file mode 100644
index efa87ce86..000000000
--- a/problems/count-number-of-homogenous-substrings/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-changes-to-make-alternating-binary-string "Minimum Changes To Make Alternating Binary String")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-limit-of-balls-in-a-bag "Minimum Limit of Balls in a Bag")
-
-## [1759. Count Number of Homogenous Substrings (Medium)](https://leetcode.com/problems/count-number-of-homogenous-substrings "统计同构子字符串的数目")
-
-<p>Given a string <code>s</code>, return <em>the number of <strong>homogenous</strong> substrings of </em><code>s</code><em>.</em> Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>A string is <strong>homogenous</strong> if all the characters of the string are the same.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abbcccaa&quot;
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> The homogenous substrings are listed as below:
-&quot;a&quot;   appears 3 times.
-&quot;aa&quot;  appears 1 time.
-&quot;b&quot;   appears 2 times.
-&quot;bb&quot;  appears 1 time.
-&quot;c&quot;   appears 3 times.
-&quot;cc&quot;  appears 2 times.
-&quot;ccc&quot; appears 1 time.
-3 + 1 + 2 + 1 + 3 + 2 + 1 = 13.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;xy&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The homogenous substrings are &quot;x&quot; and &quot;y&quot;.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;zzzzz&quot;
-<strong>Output:</strong> 15
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of lowercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A string of only 'a's of length k contains k choose 2 homogenous substrings.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Split the string into substrings where each substring contains only one letter, and apply the formula on each substring's length.
-</details>
diff --git a/problems/count-number-of-maximum-bitwise-or-subsets/README.md b/problems/count-number-of-maximum-bitwise-or-subsets/README.md
deleted file mode 100644
index 0a0609c00..000000000
--- a/problems/count-number-of-maximum-bitwise-or-subsets/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../simple-bank-system "Simple Bank System")
-　　　　　　　　　　　　　　　　
-[Next >](../second-minimum-time-to-reach-destination "Second Minimum Time to Reach Destination")
-
-## [2044. Count Number of Maximum Bitwise-OR Subsets (Medium)](https://leetcode.com/problems/count-number-of-maximum-bitwise-or-subsets "统计按位或能得到最大值的子集数目")
-
-<p>Given an integer array <code>nums</code>, find the <strong>maximum</strong> possible <strong>bitwise OR</strong> of a subset of <code>nums</code> and return <em>the <strong>number of different non-empty subsets</strong> with the maximum bitwise OR</em>.</p>
-
-<p>An array <code>a</code> is a <strong>subset</strong> of an array <code>b</code> if <code>a</code> can be obtained from <code>b</code> by deleting some (possibly zero) elements of <code>b</code>. Two subsets are considered <strong>different</strong> if the indices of the elements chosen are different.</p>
-
-<p>The bitwise OR of an array <code>a</code> is equal to <code>a[0] <strong>OR</strong> a[1] <strong>OR</strong> ... <strong>OR</strong> a[a.length - 1]</code> (<strong>0-indexed</strong>).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The maximum possible bitwise OR of a subset is 3. There are 2 subsets with a bitwise OR of 3:
-- [3]
-- [3,1]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,2]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> All non-empty subsets of [2,2,2] have a bitwise OR of 2. There are 2<sup>3</sup> - 1 = 7 total subsets.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,1,5]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The maximum possible bitwise OR of a subset is 7. There are 6 subsets with a bitwise OR of 7:
-- [3,5]
-- [3,1,5]
-- [3,2,5]
-- [3,2,1,5]
-- [2,5]
-- [2,1,5]</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 16</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we enumerate all possible subsets?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The maximum bitwise-OR is the bitwise-OR of the whole array.
-</details>
diff --git a/problems/count-number-of-nice-subarrays/README.md b/problems/count-number-of-nice-subarrays/README.md
deleted file mode 100644
index 5a88c6c6a..000000000
--- a/problems/count-number-of-nice-subarrays/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-swaps-to-make-strings-equal "Minimum Swaps to Make Strings Equal")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-remove-to-make-valid-parentheses "Minimum Remove to Make Valid Parentheses")
-
-## [1248. Count Number of Nice Subarrays (Medium)](https://leetcode.com/problems/count-number-of-nice-subarrays "统计「优美子数组」")
-
-<p>Given an array of integers <code>nums</code> and an integer <code>k</code>. A continuous subarray is called <strong>nice</strong> if there are <code>k</code> odd numbers on it.</p>
-
-<p>Return <em>the number of <strong>nice</strong> sub-arrays</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,2,1,1], k = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The only sub-arrays with 3 odd numbers are [1,1,2,1] and [1,2,1,1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,4,6], k = 1
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no odd numbers in the array.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,2,1,2,2,1,2,2,2], k = 2
-<strong>Output:</strong> 16
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 50000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10^5</code></li>
-	<li><code>1 &lt;= k &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-After replacing each even by zero and every odd by one can we use prefix sum to find answer ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use two pointers to count number of sub-arrays ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Can we store indices of odd numbers and for each k indices count number of sub-arrays contains them ?
-</details>
diff --git a/problems/count-number-of-pairs-with-absolute-difference-k/README.md b/problems/count-number-of-pairs-with-absolute-difference-k/README.md
deleted file mode 100644
index 588fa71df..000000000
--- a/problems/count-number-of-pairs-with-absolute-difference-k/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subtree-removal-game-with-fibonacci-tree "Subtree Removal Game with Fibonacci Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../find-original-array-from-doubled-array "Find Original Array From Doubled Array")
-
-## [2006. Count Number of Pairs With Absolute Difference K (Easy)](https://leetcode.com/problems/count-number-of-pairs-with-absolute-difference-k "差的绝对值为 K 的数对数目")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the number of pairs</em> <code>(i, j)</code> <em>where</em> <code>i &lt; j</code> <em>such that</em> <code>|nums[i] - nums[j]| == k</code>.</p>
-
-<p>The value of <code>|x|</code> is defined as:</p>
-
-<ul>
-	<li><code>x</code> if <code>x &gt;= 0</code>.</li>
-	<li><code>-x</code> if <code>x &lt; 0</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,2,1], k = 1
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The pairs with an absolute difference of 1 are:
-- [<strong><u>1</u></strong>,<strong><u>2</u></strong>,2,1]
-- [<strong><u>1</u></strong>,2,<strong><u>2</u></strong>,1]
-- [1,<strong><u>2</u></strong>,2,<strong><u>1</u></strong>]
-- [1,2,<strong><u>2</u></strong>,<strong><u>1</u></strong>]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3], k = 3
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no pairs with an absolute difference of 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,1,5,4], k = 2
-<strong>Output:</strong> 3
-<b>Explanation:</b> The pairs with an absolute difference of 2 are:
-- [<strong><u>3</u></strong>,2,<strong><u>1</u></strong>,5,4]
-- [<strong><u>3</u></strong>,2,1,<strong><u>5</u></strong>,4]
-- [3,<strong><u>2</u></strong>,1,5,<strong><u>4</u></strong>]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 200</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-	<li><code>1 &lt;= k &lt;= 99</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we check every possible pair?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use a nested for loop to solve this problem?
-</details>
diff --git a/problems/count-number-of-special-subsequences/README.md b/problems/count-number-of-special-subsequences/README.md
deleted file mode 100644
index 3871d7327..000000000
--- a/problems/count-number-of-special-subsequences/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-garden-perimeter-to-collect-enough-apples "Minimum Garden Perimeter to Collect Enough Apples")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-time-for-k-virus-variants-to-spread "Minimum Time For K Virus Variants to Spread")
-
-## [1955. Count Number of Special Subsequences (Hard)](https://leetcode.com/problems/count-number-of-special-subsequences "统计特殊子序列的数目")
-
-<p>A sequence is <strong>special</strong> if it consists of a <strong>positive</strong> number of <code>0</code>s, followed by a <strong>positive</strong> number of <code>1</code>s, then a <strong>positive</strong> number of <code>2</code>s.</p>
-
-<ul>
-	<li>For example, <code>[0,1,2]</code> and <code>[0,0,1,1,1,2]</code> are special.</li>
-	<li>In contrast, <code>[2,1,0]</code>, <code>[1]</code>, and <code>[0,1,2,0]</code> are not special.</li>
-</ul>
-
-<p>Given an array <code>nums</code> (consisting of <strong>only</strong> integers <code>0</code>, <code>1</code>, and <code>2</code>), return<em> the <strong>number of different subsequences</strong> that are special</em>. Since the answer may be very large, <strong>return it modulo </strong><code>10<sup>9</sup> + 7</code>.</p>
-
-<p>A <strong>subsequence</strong> of an array is a sequence that can be derived from the array by deleting some or no elements without changing the order of the remaining elements. Two subsequences are <strong>different</strong> if the <strong>set of indices</strong> chosen are different.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,2,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The special subsequences are bolded [<strong><u>0</u></strong>,<strong><u>1</u></strong>,<strong><u>2</u></strong>,2], [<strong><u>0</u></strong>,<strong><u>1</u></strong>,2,<strong><u>2</u></strong>], and [<strong><u>0</u></strong>,<strong><u>1</u></strong>,<strong><u>2</u></strong>,<strong><u>2</u></strong>].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,0,0]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no special subsequences in [2,2,0,0].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,2,0,1,2]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The special subsequences are bolded:
-- [<strong><u>0</u></strong>,<strong><u>1</u></strong>,<strong><u>2</u></strong>,0,1,2]
-- [<strong><u>0</u></strong>,<strong><u>1</u></strong>,2,0,1,<strong><u>2</u></strong>]
-- [<strong><u>0</u></strong>,<strong><u>1</u></strong>,<strong><u>2</u></strong>,0,1,<strong><u>2</u></strong>]
-- [<strong><u>0</u></strong>,<strong><u>1</u></strong>,2,0,<strong><u>1</u></strong>,<strong><u>2</u></strong>]
-- [<strong><u>0</u></strong>,1,2,<strong><u>0</u></strong>,<strong><u>1</u></strong>,<strong><u>2</u></strong>]
-- [<strong><u>0</u></strong>,1,2,0,<strong><u>1</u></strong>,<strong><u>2</u></strong>]
-- [0,1,2,<strong><u>0</u></strong>,<strong><u>1</u></strong>,<strong><u>2</u></strong>]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 2</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we first solve a simpler problem? Counting the number of subsequences with 1s followed by 0s.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we keep track of the partially matched subsequences to help us find the answer?
-</details>
diff --git a/problems/count-number-of-teams/README.md b/problems/count-number-of-teams/README.md
deleted file mode 100644
index 2fb55323d..000000000
--- a/problems/count-number-of-teams/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-lucky-integer-in-an-array "Find Lucky Integer in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../design-underground-system "Design Underground System")
-
-## [1395. Count Number of Teams (Medium)](https://leetcode.com/problems/count-number-of-teams "统计作战单位数")
-
-<p>There are <code>n</code> soldiers standing in a line. Each soldier is assigned a <strong>unique</strong> <code>rating</code> value.</p>
-
-<p>You have to form a team of 3 soldiers amongst them under the following rules:</p>
-
-<ul>
-	<li>Choose 3 soldiers with index (<code>i</code>, <code>j</code>, <code>k</code>) with rating (<code>rating[i]</code>, <code>rating[j]</code>, <code>rating[k]</code>).</li>
-	<li>A team is valid if: (<code>rating[i] &lt; rating[j] &lt; rating[k]</code>) or (<code>rating[i] &gt; rating[j] &gt; rating[k]</code>) where (<code>0 &lt;= i &lt; j &lt; k &lt; n</code>).</li>
-</ul>
-
-<p>Return the number of teams you can form given the conditions. (soldiers can be part of multiple teams).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rating = [2,5,3,4,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We can form three teams given the conditions. (2,3,4), (5,4,1), (5,3,1). 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rating = [2,1,3]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> We can&#39;t form any team given the conditions.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> rating = [1,2,3,4]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == rating.length</code></li>
-	<li><code>3 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= rating[i] &lt;= 10<sup>5</sup></code></li>
-	<li>All the integers in <code>rating</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-BruteForce, check all possibilities.
-</details>
diff --git a/problems/count-numbers-with-unique-digits/README.md b/problems/count-numbers-with-unique-digits/README.md
deleted file mode 100644
index 340f61812..000000000
--- a/problems/count-numbers-with-unique-digits/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../line-reflection "Line Reflection")
-　　　　　　　　　　　　　　　　
-[Next >](../rearrange-string-k-distance-apart "Rearrange String k Distance Apart")
-
-## [357. Count Numbers with Unique Digits (Medium)](https://leetcode.com/problems/count-numbers-with-unique-digits "计算各个位数不同的数字个数")
-
-<p>Given an integer <code>n</code>, return the count of all numbers with unique digits, <code>x</code>, where <code>0 &lt;= x &lt; 10<sup>n</sup></code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 91
-<strong>Explanation:</strong> The answer should be the total numbers in the range of 0 &le; x &lt; 100, excluding 11,22,33,44,55,66,77,88,99
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 0
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 8</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A direct way is to use the backtracking approach.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Backtracking should contains three states which are (the current number, number of steps to get that number and a bitmask which represent which number is marked as visited so far in the current number). Start with state (0,0,0) and count all valid number till we reach number of steps equals to 10<sup>n</sup>.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-This problem can also be solved using a dynamic programming approach and some knowledge of combinatorics.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Let f(k) = count of numbers with unique digits with length equals k.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-f(1) = 10, ..., f(k) = 9 * 9 * 8 * ... (9 - k + 2) [The first factor is 9 because a number cannot start with 0].
-</details>
diff --git a/problems/count-numbers-with-unique-digits/count_numbers_with_unique_digits.go b/problems/count-numbers-with-unique-digits/count_numbers_with_unique_digits.go
deleted file mode 100644
index 39ce37305..000000000
--- a/problems/count-numbers-with-unique-digits/count_numbers_with_unique_digits.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem357
diff --git a/problems/count-numbers-with-unique-digits/count_numbers_with_unique_digits_test.go b/problems/count-numbers-with-unique-digits/count_numbers_with_unique_digits_test.go
deleted file mode 100644
index 39ce37305..000000000
--- a/problems/count-numbers-with-unique-digits/count_numbers_with_unique_digits_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem357
diff --git a/problems/count-odd-numbers-in-an-interval-range/README.md b/problems/count-odd-numbers-in-an-interval-range/README.md
deleted file mode 100644
index ded9c497f..000000000
--- a/problems/count-odd-numbers-in-an-interval-range/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../diameter-of-n-ary-tree "Diameter of N-Ary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-sub-arrays-with-odd-sum "Number of Sub-arrays With Odd Sum")
-
-## [1523. Count Odd Numbers in an Interval Range (Easy)](https://leetcode.com/problems/count-odd-numbers-in-an-interval-range "在区间范围内统计奇数数目")
-
-<p>Given two non-negative integers <code>low</code> and <code><font face="monospace">high</font></code>. Return the <em>count of odd numbers between </em><code>low</code><em> and </em><code><font face="monospace">high</font></code><em>&nbsp;(inclusive)</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> low = 3, high = 7
-<strong>Output:</strong> 3
-<b>Explanation: </b>The odd numbers between 3 and 7 are [3,5,7].</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> low = 8, high = 10
-<strong>Output:</strong> 1
-<b>Explanation: </b>The odd numbers between 8 and 10 are [9].</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= low &lt;= high&nbsp;&lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the range (high - low + 1) is even, the number of even and odd numbers in this range will be the same.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the range (high - low + 1) is odd, the solution will depend on the parity of high and low.
-</details>
diff --git a/problems/count-of-matches-in-tournament/README.md b/problems/count-of-matches-in-tournament/README.md
deleted file mode 100644
index 71e5c1cba..000000000
--- a/problems/count-of-matches-in-tournament/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delivering-boxes-from-storage-to-ports "Delivering Boxes from Storage to Ports")
-　　　　　　　　　　　　　　　　
-[Next >](../partitioning-into-minimum-number-of-deci-binary-numbers "Partitioning Into Minimum Number Of Deci-Binary Numbers")
-
-## [1688. Count of Matches in Tournament (Easy)](https://leetcode.com/problems/count-of-matches-in-tournament "比赛中的配对次数")
-
-<p>You are given an integer <code>n</code>, the number of teams in a tournament that has strange rules:</p>
-
-<ul>
-	<li>If the current number of teams is <strong>even</strong>, each team gets paired with another team. A total of <code>n / 2</code> matches are played, and <code>n / 2</code> teams advance to the next round.</li>
-	<li>If the current number of teams is <strong>odd</strong>, one team randomly advances in the tournament, and the rest gets paired. A total of <code>(n - 1) / 2</code> matches are played, and <code>(n - 1) / 2 + 1</code> teams advance to the next round.</li>
-</ul>
-
-<p>Return <em>the number of matches played in the tournament until a winner is decided.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Details of the tournament: 
-- 1st Round: Teams = 7, Matches = 3, and 4 teams advance.
-- 2nd Round: Teams = 4, Matches = 2, and 2 teams advance.
-- 3rd Round: Teams = 2, Matches = 1, and 1 team is declared the winner.
-Total number of matches = 3 + 2 + 1 = 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 14
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> Details of the tournament:
-- 1st Round: Teams = 14, Matches = 7, and 7 teams advance.
-- 2nd Round: Teams = 7, Matches = 3, and 4 teams advance.
-- 3rd Round: Teams = 4, Matches = 2, and 2 teams advance.
-- 4th Round: Teams = 2, Matches = 1, and 1 team is declared the winner.
-Total number of matches = 7 + 3 + 2 + 1 = 13.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 200</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the tournament as given in the statement.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Be careful when handling odd integers.
-</details>
diff --git a/problems/count-of-range-sum/README.md b/problems/count-of-range-sum/README.md
deleted file mode 100644
index 5e070bfde..000000000
--- a/problems/count-of-range-sum/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../power-of-three "Power of Three")
-　　　　　　　　　　　　　　　　
-[Next >](../odd-even-linked-list "Odd Even Linked List")
-
-## [327. Count of Range Sum (Hard)](https://leetcode.com/problems/count-of-range-sum "区间和的个数")
-
-<p>Given an integer array <code>nums</code> and two integers <code>lower</code> and <code>upper</code>, return <em>the number of range sums that lie in</em> <code>[lower, upper]</code> <em>inclusive</em>.</p>
-
-<p>Range sum <code>S(i, j)</code> is defined as the sum of the elements in <code>nums</code> between indices <code>i</code> and <code>j</code> inclusive, where <code>i &lt;= j</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-2,5,-1], lower = -2, upper = 2
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The three ranges are: [0,0], [2,2], and [0,2] and their respective sums are: -2, -1, 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0], lower = 0, upper = 0
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>-10<sup>5</sup> &lt;= lower &lt;= upper &lt;= 10<sup>5</sup></code></li>
-	<li>The answer is <strong>guaranteed</strong> to fit in a <strong>32-bit</strong> integer.</li>
-</ul>
-
-### Related Topics
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Merge Sort](../../tag/merge-sort/README.md)]
-
-### Similar Questions
-  1. [Count of Smaller Numbers After Self](../count-of-smaller-numbers-after-self) (Hard)
-  1. [Reverse Pairs](../reverse-pairs) (Hard)
diff --git a/problems/count-of-range-sum/count_of_range_sum.go b/problems/count-of-range-sum/count_of_range_sum.go
deleted file mode 100644
index 631854742..000000000
--- a/problems/count-of-range-sum/count_of_range_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem327
diff --git a/problems/count-of-range-sum/count_of_range_sum_test.go b/problems/count-of-range-sum/count_of_range_sum_test.go
deleted file mode 100644
index 631854742..000000000
--- a/problems/count-of-range-sum/count_of_range_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem327
diff --git a/problems/count-of-smaller-numbers-after-self/README.md b/problems/count-of-smaller-numbers-after-self/README.md
deleted file mode 100644
index 70e0604bd..000000000
--- a/problems/count-of-smaller-numbers-after-self/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-vertical-order-traversal "Binary Tree Vertical Order Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-duplicate-letters "Remove Duplicate Letters")
-
-## [315. Count of Smaller Numbers After Self (Hard)](https://leetcode.com/problems/count-of-smaller-numbers-after-self "计算右侧小于当前元素的个数")
-
-<p>You are given an integer array <code>nums</code> and you have to return a new <code>counts</code> array. The <code>counts</code> array has the property where <code>counts[i]</code> is the number of smaller elements to the right of <code>nums[i]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,2,6,1]
-<strong>Output:</strong> [2,1,1,0]
-<strong>Explanation:</strong>
-To the right of 5 there are <b>2</b> smaller elements (2 and 1).
-To the right of 2 there is only <b>1</b> smaller element (1).
-To the right of 6 there is <b>1</b> smaller element (1).
-To the right of 1 there is <b>0</b> smaller element.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1]
-<strong>Output:</strong> [0]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,-1]
-<strong>Output:</strong> [0,0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Merge Sort](../../tag/merge-sort/README.md)]
-
-### Similar Questions
-  1. [Count of Range Sum](../count-of-range-sum) (Hard)
-  1. [Queue Reconstruction by Height](../queue-reconstruction-by-height) (Medium)
-  1. [Reverse Pairs](../reverse-pairs) (Hard)
diff --git a/problems/count-of-smaller-numbers-after-self/count_of_smaller_numbers_after_self.go b/problems/count-of-smaller-numbers-after-self/count_of_smaller_numbers_after_self.go
deleted file mode 100644
index 4feb2cd86..000000000
--- a/problems/count-of-smaller-numbers-after-self/count_of_smaller_numbers_after_self.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem315
diff --git a/problems/count-of-smaller-numbers-after-self/count_of_smaller_numbers_after_self_test.go b/problems/count-of-smaller-numbers-after-self/count_of_smaller_numbers_after_self_test.go
deleted file mode 100644
index 4feb2cd86..000000000
--- a/problems/count-of-smaller-numbers-after-self/count_of_smaller_numbers_after_self_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem315
diff --git a/problems/count-operations-to-obtain-zero/README.md b/problems/count-operations-to-obtain-zero/README.md
deleted file mode 100644
index 019bc3626..000000000
--- a/problems/count-operations-to-obtain-zero/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-substrings-with-equal-digit-frequency "Unique Substrings With Equal Digit Frequency")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-operations-to-make-the-array-alternating "Minimum Operations to Make the Array Alternating")
-
-## [2169. Count Operations to Obtain Zero (Easy)](https://leetcode.com/problems/count-operations-to-obtain-zero "得到 0 的操作数")
-
-<p>You are given two <strong>non-negative</strong> integers <code>num1</code> and <code>num2</code>.</p>
-
-<p>In one <strong>operation</strong>, if <code>num1 &gt;= num2</code>, you must subtract <code>num2</code> from <code>num1</code>, otherwise subtract <code>num1</code> from <code>num2</code>.</p>
-
-<ul>
-	<li>For example, if <code>num1 = 5</code> and <code>num2 = 4</code>, subtract <code>num2</code> from <code>num1</code>, thus obtaining <code>num1 = 1</code> and <code>num2 = 4</code>. However, if <code>num1 = 4</code> and <code>num2 = 5</code>, after one operation, <code>num1 = 4</code> and <code>num2 = 1</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>number of operations</strong> required to make either</em> <code>num1 = 0</code> <em>or</em> <code>num2 = 0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num1 = 2, num2 = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-- Operation 1: num1 = 2, num2 = 3. Since num1 &lt; num2, we subtract num1 from num2 and get num1 = 2, num2 = 3 - 2 = 1.
-- Operation 2: num1 = 2, num2 = 1. Since num1 &gt; num2, we subtract num2 from num1.
-- Operation 3: num1 = 1, num2 = 1. Since num1 == num2, we subtract num2 from num1.
-Now num1 = 0 and num2 = 1. Since num1 == 0, we do not need to perform any further operations.
-So the total number of operations required is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num1 = 10, num2 = 10
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 
-- Operation 1: num1 = 10, num2 = 10. Since num1 == num2, we subtract num2 from num1 and get num1 = 10 - 10 = 0.
-Now num1 = 0 and num2 = 10. Since num1 == 0, we are done.
-So the total number of operations required is 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= num1, num2 &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try simulating the process until either of the two integers is zero.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Count the number of operations done.
-</details>
diff --git a/problems/count-pairs-in-two-arrays/README.md b/problems/count-pairs-in-two-arrays/README.md
deleted file mode 100644
index 82a198799..000000000
--- a/problems/count-pairs-in-two-arrays/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../egg-drop-with-2-eggs-and-n-floors "Egg Drop With 2 Eggs and N Floors")
-　　　　　　　　　　　　　　　　
-[Next >](../determine-whether-matrix-can-be-obtained-by-rotation "Determine Whether Matrix Can Be Obtained By Rotation")
-
-## [1885. Count Pairs in Two Arrays (Medium)](https://leetcode.com/problems/count-pairs-in-two-arrays "统计数对")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can write it as nums1[i] - nums2[i] > nums2[j] - nums1[j] instead of nums1[i] + nums1[j] > nums2[i] + nums2[j].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Store nums1[idx] - nums2[idx] in a data structure.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Store nums2[idx] - nums1[idx] in a different data structure.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For each integer in the first data structure, count the number of the strictly smaller integers in the second data structure with a larger index in the original array.
-</details>
diff --git a/problems/count-pairs-of-equal-substrings-with-minimum-difference/README.md b/problems/count-pairs-of-equal-substrings-with-minimum-difference/README.md
deleted file mode 100644
index cd3d037fd..000000000
--- a/problems/count-pairs-of-equal-substrings-with-minimum-difference/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-score-of-a-good-subarray "Maximum Score of a Good Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../rearrange-products-table "Rearrange Products Table")
-
-## [1794. Count Pairs of Equal Substrings With Minimum Difference (Medium)](https://leetcode.com/problems/count-pairs-of-equal-substrings-with-minimum-difference "统计距离最小的子串对个数")
-
-
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the chosen substrings are of size larger than 1, then you can remove all but the first character from both substrings, and you'll get equal substrings of size 1, with the same a but less j. Hence, it's always optimal to choose substrings of size 1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you choose a specific letter, then it's optimal to choose its first occurrence in firstString, and its last occurrence in secondString, to minimize j-a.
-</details>
diff --git a/problems/count-pairs-of-nodes/README.md b/problems/count-pairs-of-nodes/README.md
deleted file mode 100644
index 9678daee2..000000000
--- a/problems/count-pairs-of-nodes/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-beauty-of-all-substrings "Sum of Beauty of All Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../grand-slam-titles "Grand Slam Titles")
-
-## [1782. Count Pairs Of Nodes (Hard)](https://leetcode.com/problems/count-pairs-of-nodes "统计点对的数目")
-
-<p>You are given an undirected graph defined by an integer <code>n</code>, the number of nodes, and a 2D integer array <code>edges</code>, the edges in the graph, where <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> indicates that there is an <strong>undirected</strong> edge between <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code>. You are also given an integer array <code>queries</code>.</p>
-
-<p>Let <code>incident(a, b)</code> be defined as the <strong>number of edges</strong> that are connected to <strong>either</strong> node <code>a</code> or <code>b</code>.</p>
-
-<p>The answer to the <code>j<sup>th</sup></code> query is the <strong>number of pairs</strong> of nodes <code>(a, b)</code> that satisfy <strong>both</strong> of the following conditions:</p>
-
-<ul>
-	<li><code>a &lt; b</code></li>
-	<li><code>incident(a, b) &gt; queries[j]</code></li>
-</ul>
-
-<p>Return <em>an array </em><code>answers</code><em> such that </em><code>answers.length == queries.length</code><em> and </em><code>answers[j]</code><em> is the answer of the </em><code>j<sup>th</sup></code><em> query</em>.</p>
-
-<p>Note that there can be <strong>multiple edges</strong> between the same two nodes.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/08/winword_2021-06-08_00-58-39.png" style="width: 529px; height: 305px;" />
-<pre>
-<strong>Input:</strong> n = 4, edges = [[1,2],[2,4],[1,3],[2,3],[2,1]], queries = [2,3]
-<strong>Output:</strong> [6,5]
-<strong>Explanation:</strong> The calculations for incident(a, b) are shown in the table above.
-The answers for each of the queries are as follows:
-- answers[0] = 6. All the pairs have an incident(a, b) value greater than 2.
-- answers[1] = 5. All the pairs except (3, 4) have an incident(a, b) value greater than 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, edges = [[1,5],[1,5],[3,4],[2,5],[1,3],[5,1],[2,3],[2,5]], queries = [1,2,3,4,5]
-<strong>Output:</strong> [10,10,9,8,6]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= edges.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n</code></li>
-	<li><code>u<sub>i </sub>!= v<sub>i</sub></code></li>
-	<li><code>1 &lt;= queries.length &lt;= 20</code></li>
-	<li><code>0 &lt;= queries[j] &lt; edges.length</code></li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We want to count pairs (x,y) such that degree[x] + degree[y] - occurrences(x,y) > k
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think about iterating on x, and counting the number of valid y to pair with x.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can consider at first that the (- occurrences(x,y)) isn't there, or it is 0 at first for all y. Count the valid y this way.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Then you can iterate on the neighbors of x, let that neighbor be y, and update occurrences(x,y).
-</details>
-
-<details>
-<summary>Hint 5</summary>
-When you update occurrences(x,y), the left-hand side decreases. Once it reaches k, then y is not valid for x anymore, so you should decrease the answer by 1.
-</details>
diff --git a/problems/count-pairs-with-xor-in-a-range/README.md b/problems/count-pairs-with-xor-in-a-range/README.md
deleted file mode 100644
index 1f7764e98..000000000
--- a/problems/count-pairs-with-xor-in-a-range/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-value-at-a-given-index-in-a-bounded-array "Maximum Value at a Given Index in a Bounded Array")
-　　　　　　　　　　　　　　　　
-[Next >](../implement-trie-ii-prefix-tree "Implement Trie II (Prefix Tree)")
-
-## [1803. Count Pairs With XOR in a Range (Hard)](https://leetcode.com/problems/count-pairs-with-xor-in-a-range "统计异或值在范围内的数对有多少")
-
-<p>Given a <strong>(0-indexed)</strong> integer array <code>nums</code> and two integers <code>low</code> and <code>high</code>, return <em>the number of <strong>nice pairs</strong></em>.</p>
-
-<p>A <strong>nice pair</strong> is a pair <code>(i, j)</code> where <code>0 &lt;= i &lt; j &lt; nums.length</code> and <code>low &lt;= (nums[i] XOR nums[j]) &lt;= high</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,4,2,7], low = 2, high = 6
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> All nice pairs (i, j) are as follows:
-    - (0, 1): nums[0] XOR nums[1] = 5 
-    - (0, 2): nums[0] XOR nums[2] = 3
-    - (0, 3): nums[0] XOR nums[3] = 6
-    - (1, 2): nums[1] XOR nums[2] = 6
-    - (1, 3): nums[1] XOR nums[3] = 3
-    - (2, 3): nums[2] XOR nums[3] = 5
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,8,4,2,1], low = 5, high = 14
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> All nice pairs (i, j) are as follows:
-​​​​​    - (0, 2): nums[0] XOR nums[2] = 13
-&nbsp;   - (0, 3): nums[0] XOR nums[3] = 11
-&nbsp;   - (0, 4): nums[0] XOR nums[4] = 8
-&nbsp;   - (1, 2): nums[1] XOR nums[2] = 12
-&nbsp;   - (1, 3): nums[1] XOR nums[3] = 10
-&nbsp;   - (1, 4): nums[1] XOR nums[4] = 9
-&nbsp;   - (2, 3): nums[2] XOR nums[3] = 6
-&nbsp;   - (2, 4): nums[2] XOR nums[4] = 5</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= low &lt;= high &lt;= 2 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's note that we can count all pairs with XOR ≤ K, so the answer would be to subtract the number of pairs withs XOR < low from the number of pairs with XOR ≤ high.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each value, find out the number of values when you XOR it with the result is  ≤ K using a trie.
-</details>
diff --git a/problems/count-primes/README.md b/problems/count-primes/README.md
deleted file mode 100644
index efef39034..000000000
--- a/problems/count-primes/README.md
+++ /dev/null
@@ -1,157 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-linked-list-elements "Remove Linked List Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../isomorphic-strings "Isomorphic Strings")
-
-## [204. Count Primes (Medium)](https://leetcode.com/problems/count-primes "计数质数")
-
-<p>Given an integer <code>n</code>, return <em>the number of prime numbers that are strictly less than</em> <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are 4 prime numbers less than 10, they are 2, 3, 5, 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 5 * 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-  [[Number Theory](../../tag/number-theory/README.md)]
-
-### Similar Questions
-  1. [Ugly Number](../ugly-number) (Easy)
-  1. [Ugly Number II](../ugly-number-ii) (Medium)
-  1. [Perfect Squares](../perfect-squares) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-<p>Let's start with a <i>isPrime</i> function. To determine if a number is prime, we need to check if it is not divisible by any number less than <i>n</i>. The runtime complexity of <i>isPrime</i> function would be O(<i>n</i>) and hence counting the total prime numbers up to <i>n</i> would be O(<i>n</i><sup>2</sup>). Could we do better?</p>
-</details>
-
-<details>
-<summary>Hint 2</summary>
-<p>As we know the number must not be divisible by any number > <i>n</i> / 2, we can immediately cut the total iterations half by dividing only up to <i>n</i> / 2. Could we still do better?</p>
-</details>
-
-<details>
-<summary>Hint 3</summary>
-<p>Let's write down all of 12's factors:</p>
-<pre>
-2 × 6 = 12
-3 × 4 = 12
-4 × 3 = 12
-6 × 2 = 12
-</pre>
-
-<p>As you can see, calculations of 4 × 3 and 6 × 2 are not necessary. Therefore, we only need to consider factors up to &radic;<i>n</i> because, if <i>n</i> is divisible by some number <i>p</i>, then <i>n</i> = <i>p</i> × <i>q</i> and since <i>p</i> &le; <i>q</i>, we could derive that <i>p</i> &le; &radic;<i>n</i>.</p>
-
-<p>Our total runtime has now improved to O(<i>n</i><sup>1.5</sup>), which is slightly better. Is there a faster approach?</p>
-
-<pre>
-public int countPrimes(int n) {
-   int count = 0;
-   for (int i = 1; i < n; i++) {
-      if (isPrime(i)) count++;
-   }
-   return count;
-}
-
-private boolean isPrime(int num) {
-   if (num <= 1) return false;
-   // Loop's ending condition is i * i <= num instead of i <= sqrt(num)
-   // to avoid repeatedly calling an expensive function sqrt().
-   for (int i = 2; i * i <= num; i++) {
-      if (num % i == 0) return false;
-   }
-   return true;
-}
-</pre>
-</details>
-
-<details>
-<summary>Hint 4</summary>
-<p>The <a href="http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes" target="_blank">Sieve of Eratosthenes</a> is one of the most efficient ways to find all prime numbers up to <i>n</i>. But don't let that name scare you, I promise that the concept is surprisingly simple.</p>
-
-<p>
-<img src="https://assets.leetcode.com/static_assets/public/images/solutions/Sieve_of_Eratosthenes_animation.gif" /><br />
-<small>Sieve of Eratosthenes: algorithm steps for primes below 121. "<a href="http://commons.wikimedia.org/wiki/File:Sieve_of_Eratosthenes_animation.gif" target="_blank">Sieve of Eratosthenes Animation</a>" by <a href="http://de.wikipedia.org/wiki/Benutzer:SKopp" target="_blank">SKopp</a> is licensed under <a href="http://creativecommons.org/licenses/by/2.0/" target="_blank">CC BY 2.0</a>.</small>
-</p>
-
-<p>We start off with a table of <i>n</i> numbers. Let's look at the first number, 2. We know all multiples of 2 must not be primes, so we mark them off as non-primes. Then we look at the next number, 3. Similarly, all multiples of 3 such as 3 × 2 = 6, 3 × 3 = 9, ... must not be primes, so we mark them off as well. Now we look at the next number, 4, which was already marked off. What does this tell you? Should you mark off all multiples of 4 as well?</p>
-</details>
-
-<details>
-<summary>Hint 5</summary>
-<p>4 is not a prime because it is divisible by 2, which means all multiples of 4 must also be divisible by 2 and were already marked off. So we can skip 4 immediately and go to the next number, 5. Now, all multiples of 5 such as 5 × 2 = 10, 5 × 3 = 15, 5 × 4 = 20, 5 × 5 = 25, ... can be marked off. There is a slight optimization here, we do not need to start from 5 × 2 = 10. Where should we start marking off?</p>
-</details>
-
-<details>
-<summary>Hint 6</summary>
-<p>In fact, we can mark off multiples of 5 starting at 5 × 5 = 25, because 5 × 2 = 10 was already marked off by multiple of 2, similarly 5 × 3 = 15 was already marked off by multiple of 3. Therefore, if the current number is <i>p</i>, we can always mark off multiples of <i>p</i> starting at <i>p</i><sup>2</sup>, then in increments of <i>p</i>: <i>p</i><sup>2</sup> + <i>p</i>, <i>p</i><sup>2</sup> + 2<i>p</i>, ... Now what should be the terminating loop condition?</p>
-</details>
-
-<details>
-<summary>Hint 7</summary>
-<p>It is easy to say that the terminating loop condition is <i>p</i> < <i>n</i>, which is certainly correct but not efficient. Do you still remember <i>Hint #3</i>?</p>
-</details>
-
-<details>
-<summary>Hint 8</summary>
-<p>Yes, the terminating loop condition can be <i>p</i> < &radic;<i>n</i>, as all non-primes &ge; &radic;<i>n</i> must have already been marked off. When the loop terminates, all the numbers in the table that are non-marked are prime.</p>
-
-<p>The Sieve of Eratosthenes uses an extra O(<i>n</i>) memory and its runtime complexity is O(<i>n</i> log log <i>n</i>). For the more mathematically inclined readers, you can read more about its algorithm complexity on <a href="http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes#Algorithm_complexity" target="_blank">Wikipedia</a>.</p>
-
-<pre>
-public int countPrimes(int n) {
-   boolean[] isPrime = new boolean[n];
-   for (int i = 2; i < n; i++) {
-      isPrime[i] = true;
-   }
-   // Loop's ending condition is i * i < n instead of i < sqrt(n)
-   // to avoid repeatedly calling an expensive function sqrt().
-   for (int i = 2; i * i < n; i++) {
-      if (!isPrime[i]) continue;
-      for (int j = i * i; j < n; j += i) {
-         isPrime[j] = false;
-      }
-   }
-   int count = 0;
-   for (int i = 2; i < n; i++) {
-      if (isPrime[i]) count++;
-   }
-   return count;
-}
-</pre>
-</details>
diff --git a/problems/count-primes/count_primes.go b/problems/count-primes/count_primes.go
deleted file mode 100644
index 70b6291b6..000000000
--- a/problems/count-primes/count_primes.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem204
-
-func countPrimes(n int) int {
-	if n < 3 {
-		return 0
-	}
-	primes := make([]bool, n)
-	count := 1
-	for i := 3; i < n; i += 2 {
-		if !primes[i] {
-			count++
-			for j := i * i; j < n; j += i + i {
-				primes[j] = true
-			}
-		}
-	}
-	return count
-}
diff --git a/problems/count-primes/count_primes_test.go b/problems/count-primes/count_primes_test.go
deleted file mode 100644
index f31d9bf31..000000000
--- a/problems/count-primes/count_primes_test.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem204
-
-import "testing"
-
-func TestCountPrimes(t *testing.T) {
-	tests := map[int]int{
-		0:   0,
-		1:   0,
-		2:   0,
-		3:   1,
-		5:   2,
-		7:   3,
-		10:  4,
-		100: 25,
-		200: 46,
-		300: 62,
-	}
-
-	for in, want := range tests {
-		got := countPrimes(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/count-salary-categories/README.md b/problems/count-salary-categories/README.md
deleted file mode 100644
index 5ca708082..000000000
--- a/problems/count-salary-categories/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-absolute-difference-queries "Minimum Absolute Difference Queries")
-　　　　　　　　　　　　　　　　
-[Next >](../game-of-nim "Game of Nim")
-
-## [1907. Count Salary Categories (Medium)](https://leetcode.com/problems/count-salary-categories "按分类统计薪水")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/count-salary-categories/mysql_schemas.sql b/problems/count-salary-categories/mysql_schemas.sql
deleted file mode 100644
index bca4a8114..000000000
--- a/problems/count-salary-categories/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Accounts (account_id int, income int);
-Truncate table Accounts;
-insert into Accounts (account_id, income) values ('3', '108939');
-insert into Accounts (account_id, income) values ('2', '12747');
-insert into Accounts (account_id, income) values ('8', '87709');
-insert into Accounts (account_id, income) values ('6', '91796');
diff --git a/problems/count-servers-that-communicate/README.md b/problems/count-servers-that-communicate/README.md
deleted file mode 100644
index 5e4c3cca0..000000000
--- a/problems/count-servers-that-communicate/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-time-visiting-all-points "Minimum Time Visiting All Points")
-　　　　　　　　　　　　　　　　
-[Next >](../search-suggestions-system "Search Suggestions System")
-
-## [1267. Count Servers that Communicate (Medium)](https://leetcode.com/problems/count-servers-that-communicate "统计参与通信的服务器")
-
-<p>You are given a map of a server center, represented as a <code>m * n</code> integer matrix&nbsp;<code>grid</code>, where 1 means that on that cell there is a server and 0 means that it is no server. Two servers are said to communicate if they are on the same row or on the same column.<br />
-<br />
-Return the number of servers&nbsp;that communicate with any other server.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/11/14/untitled-diagram-6.jpg" style="width: 202px; height: 203px;" /></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,0],[0,1]]
-<strong>Output:</strong> 0
-<b>Explanation:</b>&nbsp;No servers can communicate with others.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/11/13/untitled-diagram-4.jpg" style="width: 203px; height: 203px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,0],[1,1]]
-<strong>Output:</strong> 3
-<b>Explanation:</b>&nbsp;All three servers can communicate with at least one other server.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/11/14/untitled-diagram-1-3.jpg" style="width: 443px; height: 443px;" /></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,0,0],[0,0,1,0],[0,0,1,0],[0,0,0,1]]
-<strong>Output:</strong> 4
-<b>Explanation:</b>&nbsp;The two servers in the first row can communicate with each other. The two servers in the third column can communicate with each other. The server at right bottom corner can&#39;t communicate with any other server.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m &lt;= 250</code></li>
-	<li><code>1 &lt;= n &lt;= 250</code></li>
-	<li><code>grid[i][j] == 0 or 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Store number of computer in each row and column.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Count all servers that are not isolated.
-</details>
diff --git a/problems/count-sorted-vowel-strings/README.md b/problems/count-sorted-vowel-strings/README.md
deleted file mode 100644
index 9f86adbcb..000000000
--- a/problems/count-sorted-vowel-strings/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-array-formation-through-concatenation "Check Array Formation Through Concatenation")
-　　　　　　　　　　　　　　　　
-[Next >](../furthest-building-you-can-reach "Furthest Building You Can Reach")
-
-## [1641. Count Sorted Vowel Strings (Medium)](https://leetcode.com/problems/count-sorted-vowel-strings "统计字典序元音字符串的数目")
-
-<p>Given an integer <code>n</code>, return <em>the number of strings of length </em><code>n</code><em> that consist only of vowels (</em><code>a</code><em>, </em><code>e</code><em>, </em><code>i</code><em>, </em><code>o</code><em>, </em><code>u</code><em>) and are <strong>lexicographically sorted</strong>.</em></p>
-
-<p>A string <code>s</code> is <strong>lexicographically sorted</strong> if for all valid <code>i</code>, <code>s[i]</code> is the same as or comes before <code>s[i+1]</code> in the alphabet.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The 5 sorted strings that consist of vowels only are <code>[&quot;a&quot;,&quot;e&quot;,&quot;i&quot;,&quot;o&quot;,&quot;u&quot;].</code>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> The 15 sorted strings that consist of vowels only are
-[&quot;aa&quot;,&quot;ae&quot;,&quot;ai&quot;,&quot;ao&quot;,&quot;au&quot;,&quot;ee&quot;,&quot;ei&quot;,&quot;eo&quot;,&quot;eu&quot;,&quot;ii&quot;,&quot;io&quot;,&quot;iu&quot;,&quot;oo&quot;,&quot;ou&quot;,&quot;uu&quot;].
-Note that &quot;ea&quot; is not a valid string since &#39;e&#39; comes after &#39;a&#39; in the alphabet.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 33
-<strong>Output:</strong> 66045
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 50</code>&nbsp;</li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each character, its possible values will depend on the value of its previous character, because it needs to be not smaller than it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think backtracking. Build a recursive function count(n, last_character) that counts the number of valid strings of length n and whose first characters are not less than last_character.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-In this recursive function, iterate on the possible characters for the first character, which will be all the vowels not less than last_character, and for each possible value c, increase the answer by count(n-1, c).
-</details>
diff --git a/problems/count-special-quadruplets/README.md b/problems/count-special-quadruplets/README.md
deleted file mode 100644
index d9938c15d..000000000
--- a/problems/count-special-quadruplets/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-good-subsets "The Number of Good Subsets")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-weak-characters-in-the-game "The Number of Weak Characters in the Game")
-
-## [1995. Count Special Quadruplets (Easy)](https://leetcode.com/problems/count-special-quadruplets "统计特殊四元组")
-
-<p>Given a <strong>0-indexed</strong> integer array <code>nums</code>, return <em>the number of <strong>distinct</strong> quadruplets</em> <code>(a, b, c, d)</code> <em>such that:</em></p>
-
-<ul>
-	<li><code>nums[a] + nums[b] + nums[c] == nums[d]</code>, and</li>
-	<li><code>a &lt; b &lt; c &lt; d</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,6]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only quadruplet that satisfies the requirement is (0, 1, 2, 3) because 1 + 2 + 3 == 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,3,6,4,5]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no such quadruplets in [3,3,6,4,5].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,3,5]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The 4 quadruplets that satisfy the requirement are:
-- (0, 1, 2, 3): 1 + 1 + 1 == 3
-- (0, 1, 3, 4): 1 + 1 + 3 == 5
-- (0, 2, 3, 4): 1 + 1 + 3 == 5
-- (1, 2, 3, 4): 1 + 1 + 3 == 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>4 &lt;= nums.length &lt;= 50</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-N is very small, how can we use that?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we check every possible quadruplet?
-</details>
diff --git a/problems/count-square-submatrices-with-all-ones/README.md b/problems/count-square-submatrices-with-all-ones/README.md
deleted file mode 100644
index cf2e3ec9e..000000000
--- a/problems/count-square-submatrices-with-all-ones/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-burgers-with-no-waste-of-ingredients "Number of Burgers with No Waste of Ingredients")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-partitioning-iii "Palindrome Partitioning III")
-
-## [1277. Count Square Submatrices with All Ones (Medium)](https://leetcode.com/problems/count-square-submatrices-with-all-ones "统计全为 1 的正方形子矩阵")
-
-<p>Given a <code>m * n</code> matrix of ones and zeros, return how many <strong>square</strong> submatrices have all ones.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix =
-[
-&nbsp; [0,1,1,1],
-&nbsp; [1,1,1,1],
-&nbsp; [0,1,1,1]
-]
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> 
-There are <strong>10</strong> squares of side 1.
-There are <strong>4</strong> squares of side 2.
-There is  <strong>1</strong> square of side 3.
-Total number of squares = 10 + 4 + 1 = <strong>15</strong>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = 
-[
-  [1,0,1],
-  [1,1,0],
-  [1,1,0]
-]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> 
-There are <b>6</b> squares of side 1.  
-There is <strong>1</strong> square of side 2. 
-Total number of squares = 6 + 1 = <b>7</b>.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length&nbsp;&lt;= 300</code></li>
-	<li><code>1 &lt;= arr[0].length&nbsp;&lt;= 300</code></li>
-	<li><code>0 &lt;= arr[i][j] &lt;= 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create an additive table that counts the sum of elements of submatrix with the superior corner at (0,0).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop over all subsquares in O(n^3) and check if the sum make the whole array to be ones, if it checks then add 1 to the answer.
-</details>
diff --git a/problems/count-square-sum-triples/README.md b/problems/count-square-sum-triples/README.md
deleted file mode 100644
index d9d046279..000000000
--- a/problems/count-square-sum-triples/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../erect-the-fence-ii "Erect the Fence II")
-　　　　　　　　　　　　　　　　
-[Next >](../nearest-exit-from-entrance-in-maze "Nearest Exit from Entrance in Maze")
-
-## [1925. Count Square Sum Triples (Easy)](https://leetcode.com/problems/count-square-sum-triples "统计平方和三元组的数目")
-
-<p>A <strong>square triple</strong> <code>(a,b,c)</code> is a triple where <code>a</code>, <code>b</code>, and <code>c</code> are <strong>integers</strong> and <code>a<sup>2</sup> + b<sup>2</sup> = c<sup>2</sup></code>.</p>
-
-<p>Given an integer <code>n</code>, return <em>the number of <strong>square triples</strong> such that </em><code>1 &lt;= a, b, c &lt;= n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> 2
-<strong>Explanation</strong>: The square triples are (3,4,5) and (4,3,5).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 4
-<strong>Explanation</strong>: The square triples are (3,4,5), (4,3,5), (6,8,10), and (8,6,10).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 250</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate over all possible pairs (a,b) and check that the square root of a * a + b * b is an integers less than or equal n
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can check that the square root of an integer is an integer using binary seach or a builtin function like sqrt
-</details>
diff --git a/problems/count-student-number-in-departments/README.md b/problems/count-student-number-in-departments/README.md
deleted file mode 100644
index 089034b63..000000000
--- a/problems/count-student-number-in-departments/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-cumulative-salary-of-an-employee "Find Cumulative Salary of an Employee")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-unsorted-continuous-subarray "Shortest Unsorted Continuous Subarray")
-
-## [580. Count Student Number in Departments (Medium)](https://leetcode.com/problems/count-student-number-in-departments "统计各专业学生人数")
-
-<p>A university uses 2 data tables, <b><i>student</i></b> and <b><i>department</i></b>, to store data about its students and the departments associated with each major.</p>
-
-<p>Write a query to print the respective department name and number of students majoring in each department for all departments in the <b><i>department</i></b> table (even ones with no current students).</p>
-
-<p>Sort your results by descending number of students; if two or more departments have the same number of students, then sort those departments alphabetically by department name.</p>
-
-<p>The <b><i>student</i></b> is described as follow:</p>
-
-<pre>
-| Column Name  | Type      |
-|--------------|-----------|
-| student_id   | Integer   |
-| student_name | String    |
-| gender       | Character |
-| dept_id      | Integer   |
-</pre>
-
-<p>where student_id is the student&#39;s ID number, student_name is the student&#39;s name, gender is their gender, and dept_id is the department ID associated with their declared major.</p>
-
-<p>And the <b><i>department</i></b> table is described as below:</p>
-
-<pre>
-| Column Name | Type    |
-|-------------|---------|
-| dept_id     | Integer |
-| dept_name   | String  |
-</pre>
-
-<p>where dept_id is the department&#39;s ID number and dept_name is the department name.</p>
-
-<p>Here is an example <b>input</b>:<br />
-<b><i>student</i></b> table:</p>
-
-<pre>
-| student_id | student_name | gender | dept_id |
-|------------|--------------|--------|---------|
-| 1          | Jack         | M      | 1       |
-| 2          | Jane         | F      | 1       |
-| 3          | Mark         | M      | 2       |
-</pre>
-
-<p><b><i>department</i></b> table:</p>
-
-<pre>
-| dept_id | dept_name   |
-|---------|-------------|
-| 1       | Engineering |
-| 2       | Science     |
-| 3       | Law         |
-</pre>
-
-<p>The <b>Output</b> should be:</p>
-
-<pre>
-| dept_name   | student_number |
-|-------------|----------------|
-| Engineering | 2              |
-| Science     | 1              |
-| Law         | 0              |
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Still remember the difference between 'INNER JOIN' and 'OUTTER JOIN' in SQL?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Do you know other expressions using the 'COUNT' function besides 'COUNT(*)'?
-</details>
diff --git a/problems/count-student-number-in-departments/count_student_number_in_departments.sql b/problems/count-student-number-in-departments/count_student_number_in_departments.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/count-student-number-in-departments/count_student_number_in_departments.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/count-student-number-in-departments/mysql_schemas.sql b/problems/count-student-number-in-departments/mysql_schemas.sql
deleted file mode 100644
index 618e4666d..000000000
--- a/problems/count-student-number-in-departments/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Student (student_id int,student_name varchar(45), gender varchar(6), dept_id int);
-Create table If Not Exists Department (dept_id int, dept_name varchar(255));
-Truncate table Student;
-insert into Student (student_id, student_name, gender, dept_id) values ('1', 'Jack', 'M', '1');
-insert into Student (student_id, student_name, gender, dept_id) values ('2', 'Jane', 'F', '1');
-insert into Student (student_id, student_name, gender, dept_id) values ('3', 'Mark', 'M', '2');
-Truncate table Department;
-insert into Department (dept_id, dept_name) values ('1', 'Engineering');
-insert into Department (dept_id, dept_name) values ('2', 'Science');
-insert into Department (dept_id, dept_name) values ('3', 'Law');
diff --git a/problems/count-sub-islands/README.md b/problems/count-sub-islands/README.md
deleted file mode 100644
index 03d87c466..000000000
--- a/problems/count-sub-islands/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-full-rounds-you-have-played "The Number of Full Rounds You Have Played")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-absolute-difference-queries "Minimum Absolute Difference Queries")
-
-## [1905. Count Sub Islands (Medium)](https://leetcode.com/problems/count-sub-islands "统计子岛屿")
-
-<p>You are given two <code>m x n</code> binary matrices <code>grid1</code> and <code>grid2</code> containing only <code>0</code>&#39;s (representing water) and <code>1</code>&#39;s (representing land). An <strong>island</strong> is a group of <code>1</code>&#39;s connected <strong>4-directionally</strong> (horizontal or vertical). Any cells outside of the grid are considered water cells.</p>
-
-<p>An island in <code>grid2</code> is considered a <strong>sub-island </strong>if there is an island in <code>grid1</code> that contains <strong>all</strong> the cells that make up <strong>this</strong> island in <code>grid2</code>.</p>
-
-<p>Return the <em><strong>number</strong> of islands in </em><code>grid2</code> <em>that are considered <strong>sub-islands</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/10/test1.png" style="width: 493px; height: 205px;" />
-<pre>
-<strong>Input:</strong> grid1 = [[1,1,1,0,0],[0,1,1,1,1],[0,0,0,0,0],[1,0,0,0,0],[1,1,0,1,1]], grid2 = [[1,1,1,0,0],[0,0,1,1,1],[0,1,0,0,0],[1,0,1,1,0],[0,1,0,1,0]]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>In the picture above, the grid on the left is grid1 and the grid on the right is grid2.
-The 1s colored red in grid2 are those considered to be part of a sub-island. There are three sub-islands.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/03/testcasex2.png" style="width: 491px; height: 201px;" />
-<pre>
-<strong>Input:</strong> grid1 = [[1,0,1,0,1],[1,1,1,1,1],[0,0,0,0,0],[1,1,1,1,1],[1,0,1,0,1]], grid2 = [[0,0,0,0,0],[1,1,1,1,1],[0,1,0,1,0],[0,1,0,1,0],[1,0,0,0,1]]
-<strong>Output:</strong> 2 
-<strong>Explanation: </strong>In the picture above, the grid on the left is grid1 and the grid on the right is grid2.
-The 1s colored red in grid2 are those considered to be part of a sub-island. There are two sub-islands.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid1.length == grid2.length</code></li>
-	<li><code>n == grid1[i].length == grid2[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 500</code></li>
-	<li><code>grid1[i][j]</code> and <code>grid2[i][j]</code> are either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Number of Islands](../number-of-islands) (Medium)
-  1. [Number of Distinct Islands](../number-of-distinct-islands) (Medium)
-  1. [Find All Groups of Farmland](../find-all-groups-of-farmland) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's use floodfill to iterate over the islands of the second grid
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let's note that if all the cells in an island in the second grid if they are represented by land in the first grid then they are connected hence making that island a sub-island
-</details>
diff --git a/problems/count-subarrays-with-more-ones-than-zeros/README.md b/problems/count-subarrays-with-more-ones-than-zeros/README.md
deleted file mode 100644
index e91e1a9cf..000000000
--- a/problems/count-subarrays-with-more-ones-than-zeros/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-k-length-subsequence-with-occurrences-of-a-letter "Smallest K-Length Subsequence With Occurrences of a Letter")
-　　　　　　　　　　　　　　　　
-[Next >](../two-out-of-three "Two Out of Three")
-
-## [2031. Count Subarrays With More Ones Than Zeros (Medium)](https://leetcode.com/problems/count-subarrays-with-more-ones-than-zeros "1 比 0 多的子数组个数")
-
-
-
-### Related Topics
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Merge Sort](../../tag/merge-sort/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Change the zeros in nums to -1 and create a prefix sum array prefixSum using the new nums.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If prefixSum[i] for any index i in the range 0 <= i < prefixSum.length is positive, that means that there are more ones than zeros in the prefix ending at index i.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If prefixSum[j] > prefixSum[i] for two indexes i and j such that 0 <= i < j < prefixSum.length, that means that there are more ones than zeros in nums in the range [i + 1 : j] (inclusive)
-</details>
diff --git a/problems/count-submatrices-with-all-ones/README.md b/problems/count-submatrices-with-all-ones/README.md
deleted file mode 100644
index a142458a3..000000000
--- a/problems/count-submatrices-with-all-ones/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../last-moment-before-all-ants-fall-out-of-a-plank "Last Moment Before All Ants Fall Out of a Plank")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits "Minimum Possible Integer After at Most K Adjacent Swaps On Digits")
-
-## [1504. Count Submatrices With All Ones (Medium)](https://leetcode.com/problems/count-submatrices-with-all-ones "统计全 1 子矩形")
-
-<p>Given an <code>m x n</code> binary matrix <code>mat</code>, <em>return the number of <strong>submatrices</strong> that have all ones</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/27/ones1-grid.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> mat = [[1,0,1],[1,1,0],[1,1,0]]
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> 
-There are 6 rectangles of side 1x1.
-There are 2 rectangles of side 1x2.
-There are 3 rectangles of side 2x1.
-There is 1 rectangle of side 2x2. 
-There is 1 rectangle of side 3x1.
-Total number of rectangles = 6 + 2 + 3 + 1 + 1 = 13.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/27/ones2-grid.jpg" style="width: 324px; height: 245px;" />
-<pre>
-<strong>Input:</strong> mat = [[0,1,1,0],[0,1,1,1],[1,1,1,0]]
-<strong>Output:</strong> 24
-<strong>Explanation:</strong> 
-There are 8 rectangles of side 1x1.
-There are 5 rectangles of side 1x2.
-There are 2 rectangles of side 1x3. 
-There are 4 rectangles of side 2x1.
-There are 2 rectangles of side 2x2. 
-There are 2 rectangles of side 3x1. 
-There is 1 rectangle of side 3x2. 
-Total number of rectangles = 8 + 5 + 2 + 4 + 2 + 2 + 1 = 24.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m, n &lt;= 150</code></li>
-	<li><code>mat[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each row i, create an array nums where:  if mat[i][j] == 0 then nums[j] = 0 else nums[j] = nums[j-1] +1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In the row i, number of rectangles between column j and k(inclusive) and ends in row i, is equal to SUM(min(nums[j, .. idx])) where idx go from j to k.  Expected solution is O(n^3).
-</details>
diff --git a/problems/count-substrings-that-differ-by-one-character/README.md b/problems/count-substrings-that-differ-by-one-character/README.md
deleted file mode 100644
index 4250e2fc0..000000000
--- a/problems/count-substrings-that-differ-by-one-character/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../widest-vertical-area-between-two-points-containing-no-points "Widest Vertical Area Between Two Points Containing No Points")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-form-a-target-string-given-a-dictionary "Number of Ways to Form a Target String Given a Dictionary")
-
-## [1638. Count Substrings That Differ by One Character (Medium)](https://leetcode.com/problems/count-substrings-that-differ-by-one-character "统计只差一个字符的子串数目")
-
-<p>Given two strings <code>s</code> and <code>t</code>, find the number of ways you can choose a non-empty substring of <code>s</code> and replace a <strong>single character</strong> by a different character such that the resulting substring is a substring of <code>t</code>. In other words, find the number of substrings in <code>s</code> that differ from some substring in <code>t</code> by <strong>exactly</strong> one character.</p>
-
-<p>For example, the underlined substrings in <code>&quot;<u>compute</u>r&quot;</code> and <code>&quot;<u>computa</u>tion&quot;</code> only differ by the <code>&#39;e&#39;</code>/<code>&#39;a&#39;</code>, so this is a valid way.</p>
-
-<p>Return <em>the number of substrings that satisfy the condition above.</em></p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aba&quot;, t = &quot;baba&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The following are the pairs of substrings from s and t that differ by exactly 1 character:
-(&quot;<u>a</u>ba&quot;, &quot;<u>b</u>aba&quot;)
-(&quot;<u>a</u>ba&quot;, &quot;ba<u>b</u>a&quot;)
-(&quot;ab<u>a</u>&quot;, &quot;<u>b</u>aba&quot;)
-(&quot;ab<u>a</u>&quot;, &quot;ba<u>b</u>a&quot;)
-(&quot;a<u>b</u>a&quot;, &quot;b<u>a</u>ba&quot;)
-(&quot;a<u>b</u>a&quot;, &quot;bab<u>a</u>&quot;)
-The underlined portions are the substrings that are chosen from s and t.
-</pre>
-​​<strong>Example 2:</strong>
-
-<pre>
-<strong>Input:</strong> s = &quot;ab&quot;, t = &quot;bb&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The following are the pairs of substrings from s and t that differ by 1 character:
-(&quot;<u>a</u>b&quot;, &quot;<u>b</u>b&quot;)
-(&quot;<u>a</u>b&quot;, &quot;b<u>b</u>&quot;)
-(&quot;<u>ab</u>&quot;, &quot;<u>bb</u>&quot;)
-​​​​The underlined portions are the substrings that are chosen from s and t.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, t.length &lt;= 100</code></li>
-	<li><code>s</code> and <code>t</code> consist of lowercase English letters only.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Count Words Obtained After Adding a Letter](../count-words-obtained-after-adding-a-letter) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Take every substring of s, change a character, and see how many substrings of t match that substring.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a Trie to store all substrings of t as a dictionary.
-</details>
diff --git a/problems/count-substrings-with-only-one-distinct-letter/README.md b/problems/count-substrings-with-only-one-distinct-letter/README.md
deleted file mode 100644
index bb512697a..000000000
--- a/problems/count-substrings-with-only-one-distinct-letter/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reformat-department-table "Reformat Department Table")
-　　　　　　　　　　　　　　　　
-[Next >](../before-and-after-puzzle "Before and After Puzzle")
-
-## [1180. Count Substrings with Only One Distinct Letter (Easy)](https://leetcode.com/problems/count-substrings-with-only-one-distinct-letter "统计只含单一字母的子串")
-
-<p>Given a string <code>S</code>,&nbsp;return the number of substrings that have&nbsp;only <strong>one distinct</strong> letter.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> S = &quot;aaaba&quot;
-<strong>Output:</strong> 8
-<strong>Explanation: </strong>The substrings with one distinct letter are &quot;aaa&quot;, &quot;aa&quot;, &quot;a&quot;, &quot;b&quot;.
-&quot;aaa&quot; occurs 1 time.
-&quot;aa&quot; occurs 2 times.
-&quot;a&quot; occurs 4 times.
-&quot;b&quot; occurs 1 time.
-So the answer is 1 + 2 + 4 + 1 = 8.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> S = &quot;aaaaaaaaaa&quot;
-<strong>Output:</strong> 55
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= S.length &lt;= 1000</code></li>
-	<li><code>S[i]</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if we divide the string into substrings containing only one distinct character with maximal lengths?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Now that you have sub-strings with only one distinct character, Try to come up with a formula that counts the number of its sub-strings.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Alternatively, Observe that the constraints are small so you can use brute force.
-</details>
diff --git a/problems/count-subtrees-with-max-distance-between-cities/README.md b/problems/count-subtrees-with-max-distance-between-cities/README.md
deleted file mode 100644
index 4b8a8e661..000000000
--- a/problems/count-subtrees-with-max-distance-between-cities/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-two-strings-to-make-palindrome "Split Two Strings to Make Palindrome")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-font-to-fit-a-sentence-in-a-screen "Maximum Font to Fit a Sentence in a Screen")
-
-## [1617. Count Subtrees With Max Distance Between Cities (Hard)](https://leetcode.com/problems/count-subtrees-with-max-distance-between-cities "统计子树中城市之间最大距离")
-
-<p>There are <code>n</code> cities numbered from <code>1</code> to <code>n</code>. You are given an array <code>edges</code> of size <code>n-1</code>, where <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> represents a bidirectional edge between cities <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code>. There exists a unique path between each pair of cities. In other words, the cities form a <strong>tree</strong>.</p>
-
-<p>A <strong>subtree</strong> is a subset of cities where every city is reachable from every other city in the subset, where the path between each pair passes through only the cities from the subset. Two subtrees are different if there is a city in one subtree that is not present in the other.</p>
-
-<p>For each <code>d</code> from <code>1</code> to <code>n-1</code>, find the number of subtrees in which the <strong>maximum distance</strong> between any two cities in the subtree is equal to <code>d</code>.</p>
-
-<p>Return <em>an array of size</em> <code>n-1</code> <em>where the </em><code>d<sup>th</sup></code><em> </em><em>element <strong>(1-indexed)</strong> is the number of subtrees in which the <strong>maximum distance</strong> between any two cities is equal to </em><code>d</code>.</p>
-
-<p><strong>Notice</strong>&nbsp;that&nbsp;the <strong>distance</strong> between the two cities is the number of edges in the path between them.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/p1.png" style="width: 161px; height: 181px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, edges = [[1,2],[2,3],[2,4]]
-<strong>Output:</strong> [3,4,0]
-<strong>Explanation:
-</strong>The subtrees with subsets {1,2}, {2,3} and {2,4} have a max distance of 1.
-The subtrees with subsets {1,2,3}, {1,2,4}, {2,3,4} and {1,2,3,4} have a max distance of 2.
-No subtree has two nodes where the max distance between them is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, edges = [[1,2]]
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, edges = [[1,2],[2,3]]
-<strong>Output:</strong> [2,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 15</code></li>
-	<li><code>edges.length == n-1</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>1 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n</code></li>
-	<li>All pairs <code>(u<sub>i</sub>, v<sub>i</sub>)</code> are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate through every possible subtree by doing a bitmask on which vertices to include. How can you determine if a subtree is valid (all vertices are connected)?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To determine connectivity, count the number of reachable vertices starting from any included vertex and only traveling on edges connecting 2 vertices in the subtree. The count should be the same as the number of 1s in the bitmask.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The diameter is basically the maximum distance between any two nodes. Root the tree at a vertex. The answer is the max of the heights of the two largest subtrees or the longest diameter in any of the subtrees.
-</details>
diff --git a/problems/count-the-hidden-sequences/README.md b/problems/count-the-hidden-sequences/README.md
deleted file mode 100644
index 7b6dd0bc0..000000000
--- a/problems/count-the-hidden-sequences/README.md
+++ /dev/null
@@ -1,96 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-of-buying-candies-with-discount "Minimum Cost of Buying Candies With Discount")
-　　　　　　　　　　　　　　　　
-[Next >](../k-highest-ranked-items-within-a-price-range "K Highest Ranked Items Within a Price Range")
-
-## [2145. Count the Hidden Sequences (Medium)](https://leetcode.com/problems/count-the-hidden-sequences "统计隐藏数组数目")
-
-<p>You are given a <strong>0-indexed</strong> array of <code>n</code> integers <code>differences</code>, which describes the <strong>differences </strong>between each pair of <strong>consecutive </strong>integers of a <strong>hidden</strong> sequence of length <code>(n + 1)</code>. More formally, call the hidden sequence <code>hidden</code>, then we have that <code>differences[i] = hidden[i + 1] - hidden[i]</code>.</p>
-
-<p>You are further given two integers <code>lower</code> and <code>upper</code> that describe the <strong>inclusive</strong> range of values <code>[lower, upper]</code> that the hidden sequence can contain.</p>
-
-<ul>
-	<li>For example, given <code>differences = [1, -3, 4]</code>, <code>lower = 1</code>, <code>upper = 6</code>, the hidden sequence is a sequence of length <code>4</code> whose elements are in between <code>1</code> and <code>6</code> (<strong>inclusive</strong>).
-	<ul>
-		<li><code>[3, 4, 1, 5]</code> and <code>[4, 5, 2, 6]</code> are possible hidden sequences.</li>
-		<li><code>[5, 6, 3, 7]</code> is not possible since it contains an element greater than <code>6</code>.</li>
-		<li><code>[1, 2, 3, 4]</code> is not possible since the differences are not correct.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <em>the number of <strong>possible</strong> hidden sequences there are.</em> If there are no possible sequences, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> differences = [1,-3,4], lower = 1, upper = 6
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The possible hidden sequences are:
-- [3, 4, 1, 5]
-- [4, 5, 2, 6]
-Thus, we return 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> differences = [3,-4,5,1,-2], lower = -4, upper = 5
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The possible hidden sequences are:
-- [-3, 0, -4, 1, 2, 0]
-- [-2, 1, -3, 2, 3, 1]
-- [-1, 2, -2, 3, 4, 2]
-- [0, 3, -1, 4, 5, 3]
-Thus, we return 4.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> differences = [4,-7,2], lower = 3, upper = 6
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no possible hidden sequences. Thus, we return 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == differences.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= differences[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= lower &lt;= upper &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Fix the first element of the hidden sequence to any value x and ignore the given bounds. Notice that we can then determine all the other elements of the sequence by using the differences array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We will also be able to determine the difference between the minimum and maximum elements of the sequence. Notice that the value of x does not affect this.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We now have the ‘range’ of the sequence (difference between min and max element), we can then calculate how many ways there are to fit this range into the given range of lower to upper.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Answer is (upper - lower + 1) - (range of sequence)
-</details>
diff --git a/problems/count-the-number-of-consistent-strings/README.md b/problems/count-the-number-of-consistent-strings/README.md
deleted file mode 100644
index 0149ed188..000000000
--- a/problems/count-the-number-of-consistent-strings/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../invalid-tweets "Invalid Tweets")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-absolute-differences-in-a-sorted-array "Sum of Absolute Differences in a Sorted Array")
-
-## [1684. Count the Number of Consistent Strings (Easy)](https://leetcode.com/problems/count-the-number-of-consistent-strings "统计一致字符串的数目")
-
-<p>You are given a string <code>allowed</code> consisting of <strong>distinct</strong> characters and an array of strings <code>words</code>. A string is <strong>consistent </strong>if all characters in the string appear in the string <code>allowed</code>.</p>
-
-<p>Return<em> the number of <strong>consistent</strong> strings in the array </em><code>words</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> allowed = &quot;ab&quot;, words = [&quot;ad&quot;,&quot;bd&quot;,&quot;aaab&quot;,&quot;baa&quot;,&quot;badab&quot;]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Strings &quot;aaab&quot; and &quot;baa&quot; are consistent since they only contain characters &#39;a&#39; and &#39;b&#39;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> allowed = &quot;abc&quot;, words = [&quot;a&quot;,&quot;b&quot;,&quot;c&quot;,&quot;ab&quot;,&quot;ac&quot;,&quot;bc&quot;,&quot;abc&quot;]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> All strings are consistent.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> allowed = &quot;cad&quot;, words = [&quot;cc&quot;,&quot;acd&quot;,&quot;b&quot;,&quot;ba&quot;,&quot;bac&quot;,&quot;bad&quot;,&quot;ac&quot;,&quot;d&quot;]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Strings &quot;cc&quot;, &quot;acd&quot;, &quot;ac&quot;, and &quot;d&quot; are consistent.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= allowed.length &lt;=<sup> </sup>26</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 10</code></li>
-	<li>The characters in <code>allowed</code> are <strong>distinct</strong>.</li>
-	<li><code>words[i]</code> and <code>allowed</code> contain only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A string is incorrect if it contains a character that is not allowed
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Constraints are small enough for brute force
-</details>
diff --git a/problems/count-the-number-of-experiments/README.md b/problems/count-the-number-of-experiments/README.md
deleted file mode 100644
index 32f1a9733..000000000
--- a/problems/count-the-number-of-experiments/README.md
+++ /dev/null
@@ -1,14 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-people-that-can-be-caught-in-tag "Maximum Number of People That Can Be Caught in Tag")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-middle-index-in-array "Find the Middle Index in Array")
-
-## [1990. Count the Number of Experiments (Easy)](https://leetcode.com/problems/count-the-number-of-experiments "统计实验的数量")
-
-
diff --git a/problems/count-the-number-of-experiments/mysql_schemas.sql b/problems/count-the-number-of-experiments/mysql_schemas.sql
deleted file mode 100644
index 751d5694e..000000000
--- a/problems/count-the-number-of-experiments/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Experiments (experiment_id int, platform ENUM('Android', 'IOS', 'Web'), experiment_name ENUM('Reading', 'Sports', 'Programming'));
-Truncate table Experiments;
-insert into Experiments (experiment_id, platform, experiment_name) values ('4', 'IOS', 'Programming');
-insert into Experiments (experiment_id, platform, experiment_name) values ('13', 'IOS', 'Sports');
-insert into Experiments (experiment_id, platform, experiment_name) values ('14', 'Android', 'Reading');
-insert into Experiments (experiment_id, platform, experiment_name) values ('8', 'Web', 'Reading');
-insert into Experiments (experiment_id, platform, experiment_name) values ('12', 'Web', 'Reading');
-insert into Experiments (experiment_id, platform, experiment_name) values ('18', 'Web', 'Programming');
diff --git a/problems/count-the-repetitions/README.md b/problems/count-the-repetitions/README.md
deleted file mode 100644
index 7c6d44a5e..000000000
--- a/problems/count-the-repetitions/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../optimal-account-balancing "Optimal Account Balancing")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-substrings-in-wraparound-string "Unique Substrings in Wraparound String")
-
-## [466. Count The Repetitions (Hard)](https://leetcode.com/problems/count-the-repetitions "统计重复个数")
-
-<p>We define <code>str = [s, n]</code> as the string <code>str</code> which consists of the string <code>s</code> concatenated <code>n</code> times.</p>
-
-<ul>
-	<li>For example, <code>str == [&quot;abc&quot;, 3] ==&quot;abcabcabc&quot;</code>.</li>
-</ul>
-
-<p>We define that string <code>s1</code> can be obtained from string <code>s2</code> if we can remove some characters from <code>s2</code> such that it becomes <code>s1</code>.</p>
-
-<ul>
-	<li>For example, <code>s1 = &quot;abc&quot;</code> can be obtained from <code>s2 = &quot;ab<strong><u>dbe</u></strong>c&quot;</code> based on our definition by removing the bolded underlined characters.</li>
-</ul>
-
-<p>You are given two strings <code>s1</code> and <code>s2</code> and two integers <code>n1</code> and <code>n2</code>. You have the two strings <code>str1 = [s1, n1]</code> and <code>str2 = [s2, n2]</code>.</p>
-
-<p>Return <em>the maximum integer </em><code>m</code><em> such that </em><code>str = [str2, m]</code><em> can be obtained from </em><code>str1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s1 = "acb", n1 = 4, s2 = "ab", n2 = 2
-<strong>Output:</strong> 2
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s1 = "acb", n1 = 1, s2 = "acb", n2 = 1
-<strong>Output:</strong> 1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s1.length, s2.length &lt;= 100</code></li>
-	<li><code>s1</code> and <code>s2</code> consist of lowercase English letters.</li>
-	<li><code>1 &lt;= n1, n2 &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/count-the-repetitions/count_the_repetitions.go b/problems/count-the-repetitions/count_the_repetitions.go
deleted file mode 100644
index e50018ee1..000000000
--- a/problems/count-the-repetitions/count_the_repetitions.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem466
diff --git a/problems/count-the-repetitions/count_the_repetitions_test.go b/problems/count-the-repetitions/count_the_repetitions_test.go
deleted file mode 100644
index e50018ee1..000000000
--- a/problems/count-the-repetitions/count_the_repetitions_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem466
diff --git a/problems/count-triplets-that-can-form-two-arrays-of-equal-xor/README.md b/problems/count-triplets-that-can-form-two-arrays-of-equal-xor/README.md
deleted file mode 100644
index 54729a4f0..000000000
--- a/problems/count-triplets-that-can-form-two-arrays-of-equal-xor/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../build-an-array-with-stack-operations "Build an Array With Stack Operations")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-time-to-collect-all-apples-in-a-tree "Minimum Time to Collect All Apples in a Tree")
-
-## [1442. Count Triplets That Can Form Two Arrays of Equal XOR (Medium)](https://leetcode.com/problems/count-triplets-that-can-form-two-arrays-of-equal-xor "形成两个异或相等数组的三元组数目")
-
-<p>Given an array of integers <code>arr</code>.</p>
-
-<p>We want to select three indices <code>i</code>, <code>j</code> and <code>k</code> where <code>(0 &lt;= i &lt; j &lt;= k &lt; arr.length)</code>.</p>
-
-<p>Let&#39;s define <code>a</code> and <code>b</code> as follows:</p>
-
-<ul>
-	<li><code>a = arr[i] ^ arr[i + 1] ^ ... ^ arr[j - 1]</code></li>
-	<li><code>b = arr[j] ^ arr[j + 1] ^ ... ^ arr[k]</code></li>
-</ul>
-
-<p>Note that <strong>^</strong> denotes the <strong>bitwise-xor</strong> operation.</p>
-
-<p>Return <em>the number of triplets</em> (<code>i</code>, <code>j</code> and <code>k</code>) Where <code>a == b</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,3,1,6,7]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The triplets are (0,1,2), (0,2,2), (2,3,4) and (2,4,4)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,1,1,1,1]
-<strong>Output:</strong> 10
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 300</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We are searching for sub-array of length ≥ 2 and we need to split it to 2 non-empty arrays so that the xor of the first array is equal to the xor of the second array. This is equivalent to searching for sub-array with xor = 0.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep the prefix xor of arr in another array, check the xor of all sub-arrays in O(n^2), if the xor of sub-array of length x is 0 add x-1 to the answer.
-</details>
diff --git a/problems/count-unhappy-friends/README.md b/problems/count-unhappy-friends/README.md
deleted file mode 100644
index 10eb99863..000000000
--- a/problems/count-unhappy-friends/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../special-positions-in-a-binary-matrix "Special Positions in a Binary Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../min-cost-to-connect-all-points "Min Cost to Connect All Points")
-
-## [1583. Count Unhappy Friends (Medium)](https://leetcode.com/problems/count-unhappy-friends "统计不开心的朋友")
-
-<p>You are given a list of&nbsp;<code>preferences</code>&nbsp;for&nbsp;<code>n</code>&nbsp;friends, where <code>n</code> is always <strong>even</strong>.</p>
-
-<p>For each person <code>i</code>,&nbsp;<code>preferences[i]</code>&nbsp;contains&nbsp;a list of friends&nbsp;<strong>sorted</strong> in the <strong>order of preference</strong>. In other words, a friend earlier in the list is more preferred than a friend later in the list.&nbsp;Friends in&nbsp;each list are&nbsp;denoted by integers from <code>0</code> to <code>n-1</code>.</p>
-
-<p>All the friends are divided into pairs.&nbsp;The pairings are&nbsp;given in a list&nbsp;<code>pairs</code>,&nbsp;where <code>pairs[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> denotes <code>x<sub>i</sub></code>&nbsp;is paired with <code>y<sub>i</sub></code> and <code>y<sub>i</sub></code> is paired with <code>x<sub>i</sub></code>.</p>
-
-<p>However, this pairing may cause some of the friends to be unhappy.&nbsp;A friend <code>x</code>&nbsp;is unhappy if <code>x</code>&nbsp;is paired with <code>y</code>&nbsp;and there exists a friend <code>u</code>&nbsp;who&nbsp;is paired with <code>v</code>&nbsp;but:</p>
-
-<ul>
-	<li><code>x</code>&nbsp;prefers <code>u</code>&nbsp;over <code>y</code>,&nbsp;and</li>
-	<li><code>u</code>&nbsp;prefers <code>x</code>&nbsp;over <code>v</code>.</li>
-</ul>
-
-<p>Return <em>the number of unhappy friends</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, preferences = [[1, 2, 3], [3, 2, 0], [3, 1, 0], [1, 2, 0]], pairs = [[0, 1], [2, 3]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-Friend 1 is unhappy because:
-- 1 is paired with 0 but prefers 3 over 0, and
-- 3 prefers 1 over 2.
-Friend 3 is unhappy because:
-- 3 is paired with 2 but prefers 1 over 2, and
-- 1 prefers 3 over 0.
-Friends 0 and 2 are happy.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, preferences = [[1], [0]], pairs = [[1, 0]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Both friends 0 and 1 are happy.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, preferences = [[1, 3, 2], [2, 3, 0], [1, 3, 0], [0, 2, 1]], pairs = [[1, 3], [0, 2]]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 500</code></li>
-	<li><code>n</code>&nbsp;is even.</li>
-	<li><code>preferences.length&nbsp;== n</code></li>
-	<li><code>preferences[i].length&nbsp;== n - 1</code></li>
-	<li><code>0 &lt;= preferences[i][j] &lt;= n - 1</code></li>
-	<li><code>preferences[i]</code>&nbsp;does not contain <code>i</code>.</li>
-	<li>All values in&nbsp;<code>preferences[i]</code>&nbsp;are unique.</li>
-	<li><code>pairs.length&nbsp;== n/2</code></li>
-	<li><code>pairs[i].length&nbsp;== 2</code></li>
-	<li><code>x<sub>i</sub> != y<sub>i</sub></code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub>&nbsp;&lt;= n - 1</code></li>
-	<li>Each person is contained in <strong>exactly one</strong> pair.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create a matrix “rank” where rank[i][j] holds how highly friend ‘i' views ‘j’. This allows for O(1) comparisons between people
-</details>
diff --git a/problems/count-unique-characters-of-all-substrings-of-a-given-string/README.md b/problems/count-unique-characters-of-all-substrings-of-a-given-string/README.md
deleted file mode 100644
index cd6f99d95..000000000
--- a/problems/count-unique-characters-of-all-substrings-of-a-given-string/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../making-a-large-island "Making A Large Island")
-　　　　　　　　　　　　　　　　
-[Next >](../consecutive-numbers-sum "Consecutive Numbers Sum")
-
-## [828. Count Unique Characters of All Substrings of a Given String (Hard)](https://leetcode.com/problems/count-unique-characters-of-all-substrings-of-a-given-string "统计子串中的唯一字符")
-
-<p>Let&#39;s define a function <code>countUniqueChars(s)</code> that returns the number of unique characters on <code>s</code>.</p>
-
-<ul>
-	<li>For example if <code>s = &quot;LEETCODE&quot;</code> then <code>&quot;L&quot;</code>, <code>&quot;T&quot;</code>, <code>&quot;C&quot;</code>, <code>&quot;O&quot;</code>, <code>&quot;D&quot;</code> are the unique characters since they appear only once in <code>s</code>, therefore <code>countUniqueChars(s) = 5</code>.</li>
-</ul>
-
-<p>Given a string <code>s</code>, return the sum of <code>countUniqueChars(t)</code> where <code>t</code> is a substring of s.</p>
-
-<p>Notice that some substrings can be repeated so in this case you have to count the repeated ones too.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ABC&quot;
-<strong>Output:</strong> 10
-<strong>Explanation: </strong>All possible substrings are: &quot;A&quot;,&quot;B&quot;,&quot;C&quot;,&quot;AB&quot;,&quot;BC&quot; and &quot;ABC&quot;.
-Evey substring is composed with only unique letters.
-Sum of lengths of all substring is 1 + 1 + 1 + 2 + 2 + 3 = 10
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ABA&quot;
-<strong>Output:</strong> 8
-<strong>Explanation: </strong>The same as example 1, except <code>countUniqueChars</code>(&quot;ABA&quot;) = 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;LEETCODE&quot;
-<strong>Output:</strong> 92
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10</code><sup>5</sup></li>
-	<li><code>s</code> consists of uppercase English letters only.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/count-univalue-subtrees/README.md b/problems/count-univalue-subtrees/README.md
deleted file mode 100644
index e01b65cde..000000000
--- a/problems/count-univalue-subtrees/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../group-shifted-strings "Group Shifted Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../flatten-2d-vector "Flatten 2D Vector")
-
-## [250. Count Univalue Subtrees (Medium)](https://leetcode.com/problems/count-univalue-subtrees "统计同值子树")
-
-<p>Given a binary tree, count the number of uni-value subtrees.</p>
-
-<p>A Uni-value subtree means all nodes of the subtree have the same value.</p>
-
-<p><b>Example :</b></p>
-
-<pre><b>Input:</b>  root = [5,1,5,5,5,null,5]
-
-              5
-             / \
-            1   5
-           / \   \
-          5   5   5
-
-<b>Output:</b> 4
-</pre>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Subtree of Another Tree](../subtree-of-another-tree) (Easy)
-  1. [Longest Univalue Path](../longest-univalue-path) (Medium)
diff --git a/problems/count-univalue-subtrees/count_univalue_subtrees.go b/problems/count-univalue-subtrees/count_univalue_subtrees.go
deleted file mode 100644
index 22ca72b01..000000000
--- a/problems/count-univalue-subtrees/count_univalue_subtrees.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem250
diff --git a/problems/count-univalue-subtrees/count_univalue_subtrees_test.go b/problems/count-univalue-subtrees/count_univalue_subtrees_test.go
deleted file mode 100644
index 22ca72b01..000000000
--- a/problems/count-univalue-subtrees/count_univalue_subtrees_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem250
diff --git a/problems/count-vowel-substrings-of-a-string/README.md b/problems/count-vowel-substrings-of-a-string/README.md
deleted file mode 100644
index 29a590805..000000000
--- a/problems/count-vowel-substrings-of-a-string/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-spaces-cleaning-robot-cleaned "Number of Spaces Cleaning Robot Cleaned")
-　　　　　　　　　　　　　　　　
-[Next >](../vowels-of-all-substrings "Vowels of All Substrings")
-
-## [2062. Count Vowel Substrings of a String (Easy)](https://leetcode.com/problems/count-vowel-substrings-of-a-string "统计字符串中的元音子字符串")
-
-<p>A <strong>substring</strong> is a contiguous (non-empty) sequence of characters within a string.</p>
-
-<p>A <strong>vowel substring</strong> is a substring that <strong>only</strong> consists of vowels (<code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, and <code>&#39;u&#39;</code>) and has <strong>all five</strong> vowels present in it.</p>
-
-<p>Given a string <code>word</code>, return <em>the number of <strong>vowel substrings</strong> in</em> <code>word</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;aeiouu&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The vowel substrings of word are as follows (underlined):
-- &quot;<strong><u>aeiou</u></strong>u&quot;
-- &quot;<strong><u>aeiouu</u></strong>&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;unicornarihan&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Not all 5 vowels are present, so there are no vowel substrings.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;cuaieuouac&quot;
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The vowel substrings of word are as follows (underlined):
-- &quot;c<strong><u>uaieuo</u></strong>uac&quot;
-- &quot;c<strong><u>uaieuou</u></strong>ac&quot;
-- &quot;c<strong><u>uaieuoua</u></strong>c&quot;
-- &quot;cu<strong><u>aieuo</u></strong>uac&quot;
-- &quot;cu<strong><u>aieuou</u></strong>ac&quot;
-- &quot;cu<strong><u>aieuoua</u></strong>c&quot;
-- &quot;cua<strong><u>ieuoua</u></strong>c&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length &lt;= 100</code></li>
-	<li><code>word</code> consists of lowercase English letters only.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-While generating substrings starting at any index, do you need to continue generating larger substrings if you encounter a consonant?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you store the count of characters to avoid generating substrings altogether?
-</details>
diff --git a/problems/count-vowels-permutation/README.md b/problems/count-vowels-permutation/README.md
deleted file mode 100644
index ea4985e9b..000000000
--- a/problems/count-vowels-permutation/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-with-maximum-gold "Path with Maximum Gold")
-　　　　　　　　　　　　　　　　
-[Next >](../split-a-string-in-balanced-strings "Split a String in Balanced Strings")
-
-## [1220. Count Vowels Permutation (Hard)](https://leetcode.com/problems/count-vowels-permutation "统计元音字母序列的数目")
-
-<p>Given an integer <code>n</code>, your task is to count how many strings of length <code>n</code> can be formed under the following rules:</p>
-
-<ul>
-	<li>Each character is a lower case vowel&nbsp;(<code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, <code>&#39;u&#39;</code>)</li>
-	<li>Each vowel&nbsp;<code>&#39;a&#39;</code> may only be followed by an <code>&#39;e&#39;</code>.</li>
-	<li>Each vowel&nbsp;<code>&#39;e&#39;</code> may only be followed by an <code>&#39;a&#39;</code>&nbsp;or an <code>&#39;i&#39;</code>.</li>
-	<li>Each vowel&nbsp;<code>&#39;i&#39;</code> <strong>may not</strong> be followed by another <code>&#39;i&#39;</code>.</li>
-	<li>Each vowel&nbsp;<code>&#39;o&#39;</code> may only be followed by an <code>&#39;i&#39;</code> or a&nbsp;<code>&#39;u&#39;</code>.</li>
-	<li>Each vowel&nbsp;<code>&#39;u&#39;</code> may only be followed by an <code>&#39;a&#39;.</code></li>
-</ul>
-
-<p>Since the answer&nbsp;may be too large,&nbsp;return it modulo <code>10^9 + 7.</code></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> All possible strings are: &quot;a&quot;, &quot;e&quot;, &quot;i&quot; , &quot;o&quot; and &quot;u&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> All possible strings are: &quot;ae&quot;, &quot;ea&quot;, &quot;ei&quot;, &quot;ia&quot;, &quot;ie&quot;, &quot;io&quot;, &quot;iu&quot;, &quot;oi&quot;, &quot;ou&quot; and &quot;ua&quot;.
-</pre>
-
-<p><strong>Example 3:&nbsp;</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> 68</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2 * 10^4</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let dp[i][j] be the number of strings of length i that ends with the j-th vowel.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Deduce the recurrence from the given relations between vowels.
-</details>
diff --git a/problems/count-ways-to-build-rooms-in-an-ant-colony/README.md b/problems/count-ways-to-build-rooms-in-an-ant-colony/README.md
deleted file mode 100644
index 60c14efc3..000000000
--- a/problems/count-ways-to-build-rooms-in-an-ant-colony/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-wonderful-substrings "Number of Wonderful Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../leetcodify-friends-recommendations "Leetcodify Friends Recommendations")
-
-## [1916. Count Ways to Build Rooms in an Ant Colony (Hard)](https://leetcode.com/problems/count-ways-to-build-rooms-in-an-ant-colony "统计为蚁群构筑房间的不同顺序")
-
-<p>You are an ant tasked with adding <code>n</code> new rooms numbered <code>0</code> to <code>n-1</code> to your colony. You are given the expansion plan as a <strong>0-indexed</strong> integer array of length <code>n</code>, <code>prevRoom</code>, where <code>prevRoom[i]</code> indicates that you must build room <code>prevRoom[i]</code> before building room <code>i</code>, and these two rooms must be connected <strong>directly</strong>. Room <code>0</code> is already built, so <code>prevRoom[0] = -1</code>. The expansion&nbsp;plan is given such that once all the rooms are built, every room will be reachable from room <code>0</code>.</p>
-
-<p>You can only build <strong>one room</strong> at a time, and you can travel freely between rooms you have <strong>already built</strong> only if they are <strong>connected</strong>.&nbsp;You can choose to build <strong>any room</strong> as long as its <strong>previous room</strong>&nbsp;is already built.</p>
-
-<p>Return <em>the <strong>number of different orders</strong> you can build all the rooms in</em>. Since the answer may be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/19/d1.JPG" style="width: 200px; height: 212px;" />
-<pre>
-<strong>Input:</strong> prevRoom = [-1,0,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>&nbsp;There is only one way to build the additional rooms: 0 &rarr; 1 &rarr; 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<strong><img alt="" src="https://assets.leetcode.com/uploads/2021/06/19/d2.JPG" style="width: 200px; height: 239px;" /></strong>
-
-<pre>
-<strong>Input:</strong> prevRoom = [-1,0,0,1,2]
-<strong>Output:</strong> 6
-<strong>Explanation:
-</strong>The 6 ways are:
-0 &rarr; 1 &rarr; 3 &rarr; 2 &rarr; 4
-0 &rarr; 2 &rarr; 4 &rarr; 1 &rarr; 3
-0 &rarr; 1 &rarr; 2 &rarr; 3 &rarr; 4
-0 &rarr; 1 &rarr; 2 &rarr; 4 &rarr; 3
-0 &rarr; 2 &rarr; 1 &rarr; 3 &rarr; 4
-0 &rarr; 2 &rarr; 1 &rarr; 4 &rarr; 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == prevRoom.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>prevRoom[0] == -1</code></li>
-	<li><code>0 &lt;= prevRoom[i] &lt; n</code> for all <code>1 &lt;= i &lt; n</code></li>
-	<li>Every room is reachable from room <code>0</code> once all the rooms are built.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let dp[i] be the number of ways to solve the problem for the subtree of node i.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Imagine you are trying to fill an array with the order of traversal, dp[i] equals the multiplications of the number of ways to distribute the subtrees of the children of i on the array using combinatorics, multiplied bu their dp values.
-</details>
diff --git a/problems/count-ways-to-distribute-candies/README.md b/problems/count-ways-to-distribute-candies/README.md
deleted file mode 100644
index e84290d1c..000000000
--- a/problems/count-ways-to-distribute-candies/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-height-by-stacking-cuboids "Maximum Height by Stacking Cuboids ")
-　　　　　　　　　　　　　　　　
-[Next >](../daily-leads-and-partners "Daily Leads and Partners")
-
-## [1692. Count Ways to Distribute Candies (Hard)](https://leetcode.com/problems/count-ways-to-distribute-candies "计算分配糖果的不同方式")
-
-
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to define a recursive approach. For the ith candies, there will be one of the two following cases:
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the i - 1 previous candies are already distributed into k bags for the ith candy, you can have k * dp[n - 1][k] ways to distribute the ith candy. We need then to solve the state of (n - 1, k).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If the i - 1 previous candies are already distributed into k - 1 bags for the ith candy, you can have dp[n - 1][k - 1] ways to distribute the ith candy. We need then to solve the state of (n - 1, k - 1).
-</details>
-
-<details>
-<summary>Hint 4</summary>
-This approach will be too slow and will traverse some states more than once. We should use memoization to make the algorithm efficient.
-</details>
diff --git a/problems/count-ways-to-make-array-with-product/README.md b/problems/count-ways-to-make-array-with-product/README.md
deleted file mode 100644
index e96f4859a..000000000
--- a/problems/count-ways-to-make-array-with-product/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decode-xored-permutation "Decode XORed Permutation")
-　　　　　　　　　　　　　　　　
-[Next >](../latest-time-by-replacing-hidden-digits "Latest Time by Replacing Hidden Digits")
-
-## [1735. Count Ways to Make Array With Product (Hard)](https://leetcode.com/problems/count-ways-to-make-array-with-product "生成乘积数组的方案数")
-
-<p>You are given a 2D integer array, <code>queries</code>. For each <code>queries[i]</code>, where <code>queries[i] = [n<sub>i</sub>, k<sub>i</sub>]</code>, find the number of different ways you can place positive integers into an array of size <code>n<sub>i</sub></code> such that the product of the integers is <code>k<sub>i</sub></code>. As the number of ways may be too large, the answer to the <code>i<sup>th</sup></code> query is the number of ways <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>Return <em>an integer array </em><code>answer</code><em> where </em><code>answer.length == queries.length</code><em>, and </em><code>answer[i]</code><em> is the answer to the </em><code>i<sup>th</sup></code><em> query.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [[2,6],[5,1],[73,660]]
-<strong>Output:</strong> [4,1,50734910]
-<strong>Explanation:</strong>&nbsp;Each query is independent.
-[2,6]: There are 4 ways to fill an array of size 2 that multiply to 6: [1,6], [2,3], [3,2], [6,1].
-[5,1]: There is 1 way to fill an array of size 5 that multiply to 1: [1,1,1,1,1].
-[73,660]: There are 1050734917 ways to fill an array of size 73 that multiply to 660. 1050734917 modulo 10<sup>9</sup> + 7 = 50734910.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [[1,1],[2,2],[3,3],[4,4],[5,5]]
-<strong>Output:</strong> [1,2,3,10,5]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= queries.length &lt;= 10<sup>4</sup> </code></li>
-	<li><code>1 &lt;= n<sub>i</sub>, k<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Prime-factorize ki and count how many ways you can distribute the primes among the ni positions.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After prime factorizing ki, suppose there are x amount of prime factor. There are (x + n - 1) choose (n - 1) ways to distribute the x prime factors into k positions, allowing repetitions.
-</details>
diff --git a/problems/count-words-obtained-after-adding-a-letter/README.md b/problems/count-words-obtained-after-adding-a-letter/README.md
deleted file mode 100644
index b182d8fbc..000000000
--- a/problems/count-words-obtained-after-adding-a-letter/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-swaps-to-group-all-1s-together-ii "Minimum Swaps to Group All 1's Together II")
-　　　　　　　　　　　　　　　　
-[Next >](../earliest-possible-day-of-full-bloom "Earliest Possible Day of Full Bloom")
-
-## [2135. Count Words Obtained After Adding a Letter (Medium)](https://leetcode.com/problems/count-words-obtained-after-adding-a-letter "统计追加字母可以获得的单词数")
-
-<p>You are given two <strong>0-indexed</strong> arrays of strings <code>startWords</code> and <code>targetWords</code>. Each string consists of <strong>lowercase English letters</strong> only.</p>
-
-<p>For each string in <code>targetWords</code>, check if it is possible to choose a string from <code>startWords</code> and perform a <strong>conversion operation</strong> on it to be equal to that from <code>targetWords</code>.</p>
-
-<p>The <strong>conversion operation</strong> is described in the following two steps:</p>
-
-<ol>
-	<li><strong>Append</strong> any lowercase letter that is <strong>not present</strong> in the string to its end.
-	<ul>
-		<li>For example, if the string is <code>&quot;abc&quot;</code>, the letters <code>&#39;d&#39;</code>, <code>&#39;e&#39;</code>, or <code>&#39;y&#39;</code> can be added to it, but not <code>&#39;a&#39;</code>. If <code>&#39;d&#39;</code> is added, the resulting string will be <code>&quot;abcd&quot;</code>.</li>
-	</ul>
-	</li>
-	<li><strong>Rearrange</strong> the letters of the new string in <strong>any</strong> arbitrary order.
-	<ul>
-		<li>For example, <code>&quot;abcd&quot;</code> can be rearranged to <code>&quot;acbd&quot;</code>, <code>&quot;bacd&quot;</code>, <code>&quot;cbda&quot;</code>, and so on. Note that it can also be rearranged to <code>&quot;abcd&quot;</code> itself.</li>
-	</ul>
-	</li>
-</ol>
-
-<p>Return <em>the <strong>number of strings</strong> in </em><code>targetWords</code><em> that can be obtained by performing the operations on <strong>any</strong> string of </em><code>startWords</code>.</p>
-
-<p><strong>Note</strong> that you will only be verifying if the string in <code>targetWords</code> can be obtained from a string in <code>startWords</code> by performing the operations. The strings in <code>startWords</code> <strong>do not</strong> actually change during this process.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> startWords = [&quot;ant&quot;,&quot;act&quot;,&quot;tack&quot;], targetWords = [&quot;tack&quot;,&quot;act&quot;,&quot;acti&quot;]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-- In order to form targetWords[0] = &quot;tack&quot;, we use startWords[1] = &quot;act&quot;, append &#39;k&#39; to it, and rearrange &quot;actk&quot; to &quot;tack&quot;.
-- There is no string in startWords that can be used to obtain targetWords[1] = &quot;act&quot;.
-  Note that &quot;act&quot; does exist in startWords, but we <strong>must</strong> append one letter to the string before rearranging it.
-- In order to form targetWords[2] = &quot;acti&quot;, we use startWords[1] = &quot;act&quot;, append &#39;i&#39; to it, and rearrange &quot;acti&quot; to &quot;acti&quot; itself.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> startWords = [&quot;ab&quot;,&quot;a&quot;], targetWords = [&quot;abc&quot;,&quot;abcd&quot;]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-- In order to form targetWords[0] = &quot;abc&quot;, we use startWords[0] = &quot;ab&quot;, add &#39;c&#39; to it, and rearrange it to &quot;abc&quot;.
-- There is no string in startWords that can be used to obtain targetWords[1] = &quot;abcd&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= startWords.length, targetWords.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= startWords[i].length, targetWords[j].length &lt;= 26</code></li>
-	<li>Each string of <code>startWords</code> and <code>targetWords</code> consists of lowercase English letters only.</li>
-	<li>No letter occurs more than once in any string of <code>startWords</code> or <code>targetWords</code>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Which data structure can be used to efficiently check if a string exists in startWords?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After appending a letter, all letters of a string can be rearranged in any possible way. How can we use this to reduce our search space while checking if a string in targetWords can be obtained from a string in startWords?
-</details>
diff --git a/problems/counting-bits/README.md b/problems/counting-bits/README.md
deleted file mode 100644
index edcd0c085..000000000
--- a/problems/counting-bits/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../house-robber-iii "House Robber III")
-　　　　　　　　　　　　　　　　
-[Next >](../nested-list-weight-sum "Nested List Weight Sum")
-
-## [338. Counting Bits (Easy)](https://leetcode.com/problems/counting-bits "比特位计数")
-
-<p>Given an integer <code>n</code>, return <em>an array </em><code>ans</code><em> of length </em><code>n + 1</code><em> such that for each </em><code>i</code><em> </em>(<code>0 &lt;= i &lt;= n</code>)<em>, </em><code>ans[i]</code><em> is the <strong>number of </strong></em><code>1</code><em><strong>&#39;s</strong> in the binary representation of </em><code>i</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> [0,1,1]
-<strong>Explanation:</strong>
-0 --&gt; 0
-1 --&gt; 1
-2 --&gt; 10
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> [0,1,1,2,1,2]
-<strong>Explanation:</strong>
-0 --&gt; 0
-1 --&gt; 1
-2 --&gt; 10
-3 --&gt; 11
-4 --&gt; 100
-5 --&gt; 101
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>It is very easy to come up with a solution with a runtime of <code>O(n log n)</code>. Can you do it in linear time <code>O(n)</code> and possibly in a single pass?</li>
-	<li>Can you do it without using any built-in function (i.e., like <code>__builtin_popcount</code> in C++)?</li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Number of 1 Bits](../number-of-1-bits) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You should make use of what you have produced already.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Divide the numbers in ranges like [2-3], [4-7], [8-15] and so on. And try to generate new range from previous.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Or does the odd/even status of the number help you in calculating the number of 1s?
-</details>
diff --git a/problems/counting-bits/counting_bits.go b/problems/counting-bits/counting_bits.go
deleted file mode 100644
index cf3a610dc..000000000
--- a/problems/counting-bits/counting_bits.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem338
diff --git a/problems/counting-bits/counting_bits_test.go b/problems/counting-bits/counting_bits_test.go
deleted file mode 100644
index cf3a610dc..000000000
--- a/problems/counting-bits/counting_bits_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem338
diff --git a/problems/counting-elements/README.md b/problems/counting-elements/README.md
deleted file mode 100644
index 5b85f3d94..000000000
--- a/problems/counting-elements/README.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../constrained-subsequence-sum "Constrained Subsequence Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../perform-string-shifts "Perform String Shifts")
-
-## [1426. Counting Elements (Easy)](https://leetcode.com/problems/counting-elements "数元素")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use hashset to store all elements.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop again to count all valid elements.
-</details>
diff --git a/problems/countries-you-can-safely-invest-in/README.md b/problems/countries-you-can-safely-invest-in/README.md
deleted file mode 100644
index 75a1ea51b..000000000
--- a/problems/countries-you-can-safely-invest-in/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-a-file-sharing-system "Design a File Sharing System")
-　　　　　　　　　　　　　　　　
-[Next >](../can-make-arithmetic-progression-from-sequence "Can Make Arithmetic Progression From Sequence")
-
-## [1501. Countries You Can Safely Invest In (Medium)](https://leetcode.com/problems/countries-you-can-safely-invest-in "可以放心投资的国家")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Average Salary: Departments VS Company](../average-salary-departments-vs-company) (Hard)
diff --git a/problems/countries-you-can-safely-invest-in/mysql_schemas.sql b/problems/countries-you-can-safely-invest-in/mysql_schemas.sql
deleted file mode 100644
index ca07cd0eb..000000000
--- a/problems/countries-you-can-safely-invest-in/mysql_schemas.sql
+++ /dev/null
@@ -1,27 +0,0 @@
-Create table If Not Exists Person (id int, name varchar(15), phone_number varchar(11));
-Create table If Not Exists Country (name varchar(15), country_code varchar(3));
-Create table If Not Exists Calls (caller_id int, callee_id int, duration int);
-Truncate table Person;
-insert into Person (id, name, phone_number) values ('3', 'Jonathan', '051-1234567');
-insert into Person (id, name, phone_number) values ('12', 'Elvis', '051-7654321');
-insert into Person (id, name, phone_number) values ('1', 'Moncef', '212-1234567');
-insert into Person (id, name, phone_number) values ('2', 'Maroua', '212-6523651');
-insert into Person (id, name, phone_number) values ('7', 'Meir', '972-1234567');
-insert into Person (id, name, phone_number) values ('9', 'Rachel', '972-0011100');
-Truncate table Country;
-insert into Country (name, country_code) values ('Peru', '051');
-insert into Country (name, country_code) values ('Israel', '972');
-insert into Country (name, country_code) values ('Morocco', '212');
-insert into Country (name, country_code) values ('Germany', '049');
-insert into Country (name, country_code) values ('Ethiopia', '251');
-Truncate table Calls;
-insert into Calls (caller_id, callee_id, duration) values ('1', '9', '33');
-insert into Calls (caller_id, callee_id, duration) values ('2', '9', '4');
-insert into Calls (caller_id, callee_id, duration) values ('1', '2', '59');
-insert into Calls (caller_id, callee_id, duration) values ('3', '12', '102');
-insert into Calls (caller_id, callee_id, duration) values ('3', '12', '330');
-insert into Calls (caller_id, callee_id, duration) values ('12', '3', '5');
-insert into Calls (caller_id, callee_id, duration) values ('7', '9', '13');
-insert into Calls (caller_id, callee_id, duration) values ('7', '1', '3');
-insert into Calls (caller_id, callee_id, duration) values ('9', '7', '1');
-insert into Calls (caller_id, callee_id, duration) values ('1', '7', '7');
diff --git a/problems/couples-holding-hands/README.md b/problems/couples-holding-hands/README.md
deleted file mode 100644
index 517465e5d..000000000
--- a/problems/couples-holding-hands/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-plus-sign "Largest Plus Sign")
-　　　　　　　　　　　　　　　　
-[Next >](../toeplitz-matrix "Toeplitz Matrix")
-
-## [765. Couples Holding Hands (Hard)](https://leetcode.com/problems/couples-holding-hands "情侣牵手")
-
-<p>There are <code>n</code> couples sitting in <code>2n</code> seats arranged in a row and want to hold hands.</p>
-
-<p>The people and seats are represented by an integer array <code>row</code> where <code>row[i]</code> is the ID of the person sitting in the <code>i<sup>th</sup></code> seat. The couples are numbered in order, the first couple being <code>(0, 1)</code>, the second couple being <code>(2, 3)</code>, and so on with the last couple being <code>(2n - 2, 2n - 1)</code>.</p>
-
-<p>Return <em>the minimum number of swaps so that every couple is sitting side by side</em>. A swap consists of choosing any two people, then they stand up and switch seats.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> row = [0,2,1,3]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> We only need to swap the second (row[1]) and third (row[2]) person.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> row = [3,2,0,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> All couples are already seated side by side.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2n == row.length</code></li>
-	<li><code>2 &lt;= n &lt;= 30</code></li>
-	<li><code>n</code> is even.</li>
-	<li><code>0 &lt;= row[i] &lt; 2n</code></li>
-	<li>All the elements of <code>row</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [First Missing Positive](../first-missing-positive) (Hard)
-  1. [Missing Number](../missing-number) (Easy)
-  1. [K-Similar Strings](../k-similar-strings) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Say there are N two-seat couches.  For each couple, draw an edge from the couch of one partner to the couch of the other partner.
-</details>
diff --git a/problems/couples-holding-hands/couples_holding_hands.go b/problems/couples-holding-hands/couples_holding_hands.go
deleted file mode 100644
index 4a3016bc7..000000000
--- a/problems/couples-holding-hands/couples_holding_hands.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem765
diff --git a/problems/couples-holding-hands/couples_holding_hands_test.go b/problems/couples-holding-hands/couples_holding_hands_test.go
deleted file mode 100644
index 4a3016bc7..000000000
--- a/problems/couples-holding-hands/couples_holding_hands_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem765
diff --git a/problems/course-schedule-ii/README.md b/problems/course-schedule-ii/README.md
deleted file mode 100644
index e84e3bcf3..000000000
--- a/problems/course-schedule-ii/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-size-subarray-sum "Minimum Size Subarray Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../design-add-and-search-words-data-structure "Design Add and Search Words Data Structure")
-
-## [210. Course Schedule II (Medium)](https://leetcode.com/problems/course-schedule-ii "课程表 II")
-
-<p>There are a total of <code>numCourses</code> courses you have to take, labeled from <code>0</code> to <code>numCourses - 1</code>. You are given an array <code>prerequisites</code> where <code>prerequisites[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that you <strong>must</strong> take course <code>b<sub>i</sub></code> first if you want to take course <code>a<sub>i</sub></code>.</p>
-
-<ul>
-	<li>For example, the pair <code>[0, 1]</code>, indicates that to take course <code>0</code> you have to first take course <code>1</code>.</li>
-</ul>
-
-<p>Return <em>the ordering of courses you should take to finish all courses</em>. If there are many valid answers, return <strong>any</strong> of them. If it is impossible to finish all courses, return <strong>an empty array</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> numCourses = 2, prerequisites = [[1,0]]
-<strong>Output:</strong> [0,1]
-<strong>Explanation:</strong> There are a total of 2 courses to take. To take course 1 you should have finished course 0. So the correct course order is [0,1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> numCourses = 4, prerequisites = [[1,0],[2,0],[3,1],[3,2]]
-<strong>Output:</strong> [0,2,1,3]
-<strong>Explanation:</strong> There are a total of 4 courses to take. To take course 3 you should have finished both courses 1 and 2. Both courses 1 and 2 should be taken after you finished course 0.
-So one correct course order is [0,1,2,3]. Another correct ordering is [0,2,1,3].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> numCourses = 1, prerequisites = []
-<strong>Output:</strong> [0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= numCourses &lt;= 2000</code></li>
-	<li><code>0 &lt;= prerequisites.length &lt;= numCourses * (numCourses - 1)</code></li>
-	<li><code>prerequisites[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt; numCourses</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-	<li>All the pairs <code>[a<sub>i</sub>, b<sub>i</sub>]</code> are <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-
-### Similar Questions
-  1. [Course Schedule](../course-schedule) (Medium)
-  1. [Alien Dictionary](../alien-dictionary) (Hard)
-  1. [Minimum Height Trees](../minimum-height-trees) (Medium)
-  1. [Sequence Reconstruction](../sequence-reconstruction) (Medium)
-  1. [Course Schedule III](../course-schedule-iii) (Hard)
-  1. [Parallel Courses](../parallel-courses) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-This problem is equivalent to finding the topological order in a directed graph. If a cycle exists, no topological ordering exists and therefore it will be impossible to take all courses.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-<a href="https://class.coursera.org/algo-003/lecture/52" target="_blank">Topological Sort via DFS</a> - A great video tutorial (21 minutes) on Coursera explaining the basic concepts of Topological Sort.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Topological sort could also be done via <a href="http://en.wikipedia.org/wiki/Topological_sorting#Algorithms" target="_blank">BFS</a>.
-</details>
diff --git a/problems/course-schedule-ii/course_schedule_ii.go b/problems/course-schedule-ii/course_schedule_ii.go
deleted file mode 100644
index bb91c4a93..000000000
--- a/problems/course-schedule-ii/course_schedule_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem210
diff --git a/problems/course-schedule-ii/course_schedule_ii_test.go b/problems/course-schedule-ii/course_schedule_ii_test.go
deleted file mode 100644
index bb91c4a93..000000000
--- a/problems/course-schedule-ii/course_schedule_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem210
diff --git a/problems/course-schedule-iii/README.md b/problems/course-schedule-iii/README.md
deleted file mode 100644
index bdfa941a0..000000000
--- a/problems/course-schedule-iii/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-inverse-pairs-array "K Inverse Pairs Array")
-　　　　　　　　　　　　　　　　
-[Next >](../design-excel-sum-formula "Design Excel Sum Formula")
-
-## [630. Course Schedule III (Hard)](https://leetcode.com/problems/course-schedule-iii "课程表 III")
-
-<p>There are <code>n</code> different online courses numbered from <code>1</code> to <code>n</code>. You are given an array <code>courses</code> where <code>courses[i] = [duration<sub>i</sub>, lastDay<sub>i</sub>]</code> indicate that the <code>i<sup>th</sup></code> course should be taken <b>continuously</b> for <code>duration<sub>i</sub></code> days and must be finished before or on <code>lastDay<sub>i</sub></code>.</p>
-
-<p>You will start on the <code>1<sup>st</sup></code> day and you cannot take two or more courses simultaneously.</p>
-
-<p>Return <em>the maximum number of courses that you can take</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> courses = [[100,200],[200,1300],[1000,1250],[2000,3200]]
-<strong>Output:</strong> 3
-Explanation: 
-There are totally 4 courses, but you can take 3 courses at most:
-First, take the 1<sup>st</sup> course, it costs 100 days so you will finish it on the 100<sup>th</sup> day, and ready to take the next course on the 101<sup>st</sup> day.
-Second, take the 3<sup>rd</sup> course, it costs 1000 days so you will finish it on the 1100<sup>th</sup> day, and ready to take the next course on the 1101<sup>st</sup> day. 
-Third, take the 2<sup>nd</sup> course, it costs 200 days so you will finish it on the 1300<sup>th</sup> day. 
-The 4<sup>th</sup> course cannot be taken now, since you will finish it on the 3300<sup>th</sup> day, which exceeds the closed date.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> courses = [[1,2]]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> courses = [[3,2],[4,3]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= courses.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= duration<sub>i</sub>, lastDay<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Course Schedule](../course-schedule) (Medium)
-  1. [Course Schedule II](../course-schedule-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-During iteration, say I want to add the current course, currentTotalTime being total time of all courses taken till now, but adding the current course might exceed my deadline or it doesn’t.</br></br>
-
-1. If it doesn’t, then I have added one new course. Increment the currentTotalTime with duration of current course.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-2. If it exceeds deadline, I can swap current course with current courses that has biggest duration.</br>
-* No harm done and I might have just reduced the currentTotalTime, right? </br>
-* What preprocessing do I need to do on my course processing order so that this swap is always legal?
-</details>
diff --git a/problems/course-schedule-iii/course_schedule_iii.go b/problems/course-schedule-iii/course_schedule_iii.go
deleted file mode 100644
index b4237004c..000000000
--- a/problems/course-schedule-iii/course_schedule_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem630
diff --git a/problems/course-schedule-iii/course_schedule_iii_test.go b/problems/course-schedule-iii/course_schedule_iii_test.go
deleted file mode 100644
index b4237004c..000000000
--- a/problems/course-schedule-iii/course_schedule_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem630
diff --git a/problems/course-schedule-iv/README.md b/problems/course-schedule-iv/README.md
deleted file mode 100644
index 261ed9931..000000000
--- a/problems/course-schedule-iv/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-a-string-contains-all-binary-codes-of-size-k "Check If a String Contains All Binary Codes of Size K")
-　　　　　　　　　　　　　　　　
-[Next >](../cherry-pickup-ii "Cherry Pickup II")
-
-## [1462. Course Schedule IV (Medium)](https://leetcode.com/problems/course-schedule-iv "课程表 IV")
-
-<p>There are a total of <code>numCourses</code> courses you have to take, labeled from <code>0</code> to <code>numCourses - 1</code>. You are given an array <code>prerequisites</code> where <code>prerequisites[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that you <strong>must</strong> take course <code>a<sub>i</sub></code> first if you want to take course <code>b<sub>i</sub></code>.</p>
-
-<ul>
-	<li>For example, the pair <code>[0, 1]</code> indicates that you have to take course <code>0</code> before you can take course <code>1</code>.</li>
-</ul>
-
-<p>Prerequisites can also be <strong>indirect</strong>. If course <code>a</code> is a prerequisite of course <code>b</code>, and course <code>b</code> is a prerequisite of course <code>c</code>, then course <code>a</code> is a prerequisite of course <code>c</code>.</p>
-
-<p>You are also given an array <code>queries</code> where <code>queries[j] = [u<sub>j</sub>, v<sub>j</sub>]</code>. For the <code>j<sup>th</sup></code> query, you should answer whether course <code>u<sub>j</sub></code> is a prerequisite of course <code>v<sub>j</sub></code> or not.</p>
-
-<p>Return <i>a boolean array </i><code>answer</code><i>, where </i><code>answer[j]</code><i> is the answer to the </i><code>j<sup>th</sup></code><i> query.</i></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/01/courses4-1-graph.jpg" style="width: 222px; height: 62px;" />
-<pre>
-<strong>Input:</strong> numCourses = 2, prerequisites = [[1,0]], queries = [[0,1],[1,0]]
-<strong>Output:</strong> [false,true]
-<strong>Explanation:</strong> The pair [1, 0] indicates that you have to take course 1 before you can take course 0.
-Course 0 is not a prerequisite of course 1, but the opposite is true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> numCourses = 2, prerequisites = [], queries = [[1,0],[0,1]]
-<strong>Output:</strong> [false,false]
-<strong>Explanation:</strong> There are no prerequisites, and each course is independent.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/01/courses4-3-graph.jpg" style="width: 222px; height: 222px;" />
-<pre>
-<strong>Input:</strong> numCourses = 3, prerequisites = [[1,2],[1,0],[2,0]], queries = [[1,0],[1,2]]
-<strong>Output:</strong> [true,true]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= numCourses &lt;= 100</code></li>
-	<li><code>0 &lt;= prerequisites.length &lt;= (numCourses * (numCourses - 1) / 2)</code></li>
-	<li><code>prerequisites[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-	<li>All the pairs <code>[a<sub>i</sub>, b<sub>i</sub>]</code> are <strong>unique</strong>.</li>
-	<li>The prerequisites graph has no cycles.</li>
-	<li><code>1 &lt;= queries.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>u<sub>i</sub> != v<sub>i</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Imagine if the courses are nodes of a graph. We need to build an array isReachable[i][j].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Start a bfs from each course i and assign for each course j you visit isReachable[i][j] = True.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Answer the queries from the isReachable array.
-</details>
diff --git a/problems/course-schedule/README.md b/problems/course-schedule/README.md
deleted file mode 100644
index 974381397..000000000
--- a/problems/course-schedule/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-linked-list "Reverse Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../implement-trie-prefix-tree "Implement Trie (Prefix Tree)")
-
-## [207. Course Schedule (Medium)](https://leetcode.com/problems/course-schedule "课程表")
-
-<p>There are a total of <code>numCourses</code> courses you have to take, labeled from <code>0</code> to <code>numCourses - 1</code>. You are given an array <code>prerequisites</code> where <code>prerequisites[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that you <strong>must</strong> take course <code>b<sub>i</sub></code> first if you want to take course <code>a<sub>i</sub></code>.</p>
-
-<ul>
-	<li>For example, the pair <code>[0, 1]</code>, indicates that to take course <code>0</code> you have to first take course <code>1</code>.</li>
-</ul>
-
-<p>Return <code>true</code> if you can finish all courses. Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> numCourses = 2, prerequisites = [[1,0]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> There are a total of 2 courses to take. 
-To take course 1 you should have finished course 0. So it is possible.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> numCourses = 2, prerequisites = [[1,0],[0,1]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There are a total of 2 courses to take. 
-To take course 1 you should have finished course 0, and to take course 0 you should also have finished course 1. So it is impossible.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= numCourses &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= prerequisites.length &lt;= 5000</code></li>
-	<li><code>prerequisites[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt; numCourses</code></li>
-	<li>All the pairs prerequisites[i] are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-
-### Similar Questions
-  1. [Course Schedule II](../course-schedule-ii) (Medium)
-  1. [Graph Valid Tree](../graph-valid-tree) (Medium)
-  1. [Minimum Height Trees](../minimum-height-trees) (Medium)
-  1. [Course Schedule III](../course-schedule-iii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-This problem is equivalent to finding if a cycle exists in a directed graph. If a cycle exists, no topological ordering exists and therefore it will be impossible to take all courses.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-<a href="https://class.coursera.org/algo-003/lecture/52" target="_blank">Topological Sort via DFS</a> - A great video tutorial (21 minutes) on Coursera explaining the basic concepts of Topological Sort.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Topological sort could also be done via <a href="http://en.wikipedia.org/wiki/Topological_sorting#Algorithms" target="_blank">BFS</a>.
-</details>
diff --git a/problems/course-schedule/course_schedule.go b/problems/course-schedule/course_schedule.go
deleted file mode 100644
index f7f62e168..000000000
--- a/problems/course-schedule/course_schedule.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem207
diff --git a/problems/course-schedule/course_schedule_test.go b/problems/course-schedule/course_schedule_test.go
deleted file mode 100644
index f7f62e168..000000000
--- a/problems/course-schedule/course_schedule_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem207
diff --git a/problems/cousins-in-binary-tree/README.md b/problems/cousins-in-binary-tree/README.md
deleted file mode 100644
index 1acce6499..000000000
--- a/problems/cousins-in-binary-tree/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subarrays-with-k-different-integers "Subarrays with K Different Integers")
-　　　　　　　　　　　　　　　　
-[Next >](../rotting-oranges "Rotting Oranges")
-
-## [993. Cousins in Binary Tree (Easy)](https://leetcode.com/problems/cousins-in-binary-tree "二叉树的堂兄弟节点")
-
-<p>Given the <code>root</code> of a binary tree with unique values and the values of two different nodes of the tree <code>x</code> and <code>y</code>, return <code>true</code> <em>if the nodes corresponding to the values </em><code>x</code><em> and </em><code>y</code><em> in the tree are <strong>cousins</strong>, or </em><code>false</code><em> otherwise.</em></p>
-
-<p>Two nodes of a binary tree are <strong>cousins</strong> if they have the same depth with different parents.</p>
-
-<p>Note that in a binary tree, the root node is at the depth <code>0</code>, and children of each depth <code>k</code> node are at the depth <code>k + 1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/12/q1248-01.png" style="width: 304px; height: 270px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4], x = 4, y = 3
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/12/q1248-02.png" style="width: 334px; height: 266px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,null,4,null,5], x = 5, y = 4
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/13/q1248-03.png" style="width: 267px; height: 258px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,null,4], x = 2, y = 3
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[2, 100]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
-	<li>Each node has a <strong>unique</strong> value.</li>
-	<li><code>x != y</code></li>
-	<li><code>x</code> and <code>y</code> are exist in the tree.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Level Order Traversal](../binary-tree-level-order-traversal) (Medium)
diff --git a/problems/cousins-in-binary-tree/cousins_in_binary_tree.go b/problems/cousins-in-binary-tree/cousins_in_binary_tree.go
deleted file mode 100644
index 20991940b..000000000
--- a/problems/cousins-in-binary-tree/cousins_in_binary_tree.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem993
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func isCousins(root *TreeNode, x int, y int) bool {
-	xp, yp, xd, yd, depth := 0, 0, 0, 0, 0
-	queue := []*TreeNode{root}
-	for l := len(queue); l > 0 && xd == 0 && yd == 0; l = len(queue) {
-		for _, node := range queue {
-			if node.Left != nil {
-				if node.Left.Val == x {
-					xp, xd = node.Val, depth+1
-				} else if node.Left.Val == y {
-					yp, yd = node.Val, depth+1
-				} else {
-					queue = append(queue, node.Left)
-				}
-			}
-			if node.Right != nil {
-				if node.Right.Val == x {
-					xp, xd = node.Val, depth+1
-				} else if node.Right.Val == y {
-					yp, yd = node.Val, depth+1
-				} else {
-					queue = append(queue, node.Right)
-				}
-			}
-		}
-		depth, queue = depth+1, queue[l:]
-	}
-	return xp != yp && xd == yd
-}
diff --git a/problems/cousins-in-binary-tree/cousins_in_binary_tree_test.go b/problems/cousins-in-binary-tree/cousins_in_binary_tree_test.go
deleted file mode 100644
index 5b3a94ed9..000000000
--- a/problems/cousins-in-binary-tree/cousins_in_binary_tree_test.go
+++ /dev/null
@@ -1,55 +0,0 @@
-package problem993
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	x    int
-	y    int
-	want bool
-}
-
-func TestIsCousins(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3, 4},
-			x:    4,
-			y:    3,
-			want: false,
-		},
-		{
-			in:   []int{1, 2, 3, kit.NULL, 4, kit.NULL, 5},
-			x:    5,
-			y:    4,
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 3, kit.NULL, 4},
-			x:    2,
-			y:    3,
-			want: false,
-		},
-		{
-			in:   []int{1, 2, 3, kit.NULL, 4, 5},
-			x:    4,
-			y:    5,
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 3, kit.NULL, 4, 5},
-			x:    5,
-			y:    4,
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := isCousins(kit.SliceInt2TreeNode(tt.in), tt.x, tt.y)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/cracking-the-safe/README.md b/problems/cracking-the-safe/README.md
deleted file mode 100644
index 17db621dd..000000000
--- a/problems/cracking-the-safe/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../open-the-lock "Open the Lock")
-　　　　　　　　　　　　　　　　
-[Next >](../reach-a-number "Reach a Number")
-
-## [753. Cracking the Safe (Hard)](https://leetcode.com/problems/cracking-the-safe "破解保险箱")
-
-<p>There is a safe protected by a password. The password is a sequence of <code>n</code> digits where each digit can be in the range <code>[0, k - 1]</code>.</p>
-
-<p>The safe has a peculiar way of checking the password. When you enter in a sequence, it checks the <strong>most recent </strong><code>n</code><strong> digits</strong> that were entered each time you type a digit.</p>
-
-<ul>
-	<li>For example, the correct password is <code>&quot;345&quot;</code> and you enter in <code>&quot;012345&quot;</code>:
-	<ul>
-		<li>After typing <code>0</code>, the most recent <code>3</code> digits is <code>&quot;0&quot;</code>, which is incorrect.</li>
-		<li>After typing <code>1</code>, the most recent <code>3</code> digits is <code>&quot;01&quot;</code>, which is incorrect.</li>
-		<li>After typing <code>2</code>, the most recent <code>3</code> digits is <code>&quot;012&quot;</code>, which is incorrect.</li>
-		<li>After typing <code>3</code>, the most recent <code>3</code> digits is <code>&quot;123&quot;</code>, which is incorrect.</li>
-		<li>After typing <code>4</code>, the most recent <code>3</code> digits is <code>&quot;234&quot;</code>, which is incorrect.</li>
-		<li>After typing <code>5</code>, the most recent <code>3</code> digits is <code>&quot;345&quot;</code>, which is correct and the safe unlocks.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <em>any string of <strong>minimum length</strong> that will unlock the safe <strong>at some point</strong> of entering it</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, k = 2
-<strong>Output:</strong> &quot;10&quot;
-<strong>Explanation:</strong> The password is a single digit, so enter each digit. &quot;01&quot; would also unlock the safe.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, k = 2
-<strong>Output:</strong> &quot;01100&quot;
-<strong>Explanation:</strong> For each possible password:
-- &quot;00&quot; is typed in starting from the 4<sup>th</sup> digit.
-- &quot;01&quot; is typed in starting from the 1<sup>st</sup> digit.
-- &quot;10&quot; is typed in starting from the 3<sup>rd</sup> digit.
-- &quot;11&quot; is typed in starting from the 2<sup>nd</sup> digit.
-Thus &quot;01100&quot; will unlock the safe. &quot;01100&quot;, &quot;10011&quot;, and &quot;11001&quot; would also unlock the safe.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 4</code></li>
-	<li><code>1 &lt;= k &lt;= 10</code></li>
-	<li><code>1 &lt;= k<sup>n</sup> &lt;= 4096</code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Eulerian Circuit](../../tag/eulerian-circuit/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can think of this problem as the problem of finding an Euler path (a path visiting every edge exactly once) on the following graph: there are $$k^{n-1}$$ nodes with each node having $$k$$ edges.  It turns out this graph always has an Eulerian circuit (path starting where it ends.)
-
-We should visit each node in "post-order" so as to not get stuck in the graph prematurely.
-</details>
diff --git a/problems/cracking-the-safe/cracking_the_safe.go b/problems/cracking-the-safe/cracking_the_safe.go
deleted file mode 100644
index 494f1fd57..000000000
--- a/problems/cracking-the-safe/cracking_the_safe.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem753
diff --git a/problems/cracking-the-safe/cracking_the_safe_test.go b/problems/cracking-the-safe/cracking_the_safe_test.go
deleted file mode 100644
index 494f1fd57..000000000
--- a/problems/cracking-the-safe/cracking_the_safe_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem753
diff --git a/problems/crawler-log-folder/README.md b/problems/crawler-log-folder/README.md
deleted file mode 100644
index dc6240635..000000000
--- a/problems/crawler-log-folder/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../build-binary-expression-tree-from-infix-expression "Build Binary Expression Tree From Infix Expression")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-profit-of-operating-a-centennial-wheel "Maximum Profit of Operating a Centennial Wheel")
-
-## [1598. Crawler Log Folder (Easy)](https://leetcode.com/problems/crawler-log-folder "文件夹操作日志搜集器")
-
-<p>The Leetcode file system keeps a log each time some user performs a <em>change folder</em> operation.</p>
-
-<p>The operations are described below:</p>
-
-<ul>
-	<li><code>&quot;../&quot;</code> : Move to the parent folder of the current folder. (If you are already in the main folder, <strong>remain in the same folder</strong>).</li>
-	<li><code>&quot;./&quot;</code> : Remain in the same folder.</li>
-	<li><code>&quot;x/&quot;</code> : Move to the child folder named <code>x</code> (This folder is <strong>guaranteed to always exist</strong>).</li>
-</ul>
-
-<p>You are given a list of strings <code>logs</code> where <code>logs[i]</code> is the operation performed by the user at the <code>i<sup>th</sup></code> step.</p>
-
-<p>The file system starts in the main folder, then the operations in <code>logs</code> are performed.</p>
-
-<p>Return <em>the minimum number of operations needed to go back to the main folder after the change folder operations.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/09/09/sample_11_1957.png" style="width: 775px; height: 151px;" /></p>
-
-<pre>
-<strong>Input:</strong> logs = [&quot;d1/&quot;,&quot;d2/&quot;,&quot;../&quot;,&quot;d21/&quot;,&quot;./&quot;]
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>Use this change folder operation &quot;../&quot; 2 times and go back to the main folder.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/09/09/sample_22_1957.png" style="width: 600px; height: 270px;" /></p>
-
-<pre>
-<strong>Input:</strong> logs = [&quot;d1/&quot;,&quot;d2/&quot;,&quot;./&quot;,&quot;d3/&quot;,&quot;../&quot;,&quot;d31/&quot;]
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> logs = [&quot;d1/&quot;,&quot;../&quot;,&quot;../&quot;,&quot;../&quot;]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= logs.length &lt;= 10<sup>3</sup></code></li>
-	<li><code>2 &lt;= logs[i].length &lt;= 10</code></li>
-	<li><code>logs[i]</code> contains lowercase English letters, digits, <code>&#39;.&#39;</code>, and <code>&#39;/&#39;</code>.</li>
-	<li><code>logs[i]</code> follows the format described in the statement.</li>
-	<li>Folder names consist of lowercase English letters and digits.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-
-### Similar Questions
-  1. [Baseball Game](../baseball-game) (Easy)
-  1. [Backspace String Compare](../backspace-string-compare) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process but don’t move the pointer beyond the main folder.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Simulate the process but don’t move the pointer beyond the main folder.
-</details>
diff --git a/problems/create-a-session-bar-chart/README.md b/problems/create-a-session-bar-chart/README.md
deleted file mode 100644
index 2d98529f9..000000000
--- a/problems/create-a-session-bar-chart/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-wear-different-hats-to-each-other "Number of Ways to Wear Different Hats to Each Other")
-　　　　　　　　　　　　　　　　
-[Next >](../destination-city "Destination City")
-
-## [1435. Create a Session Bar Chart (Easy)](https://leetcode.com/problems/create-a-session-bar-chart "制作会话柱状图")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Count Salary Categories](../count-salary-categories) (Medium)
diff --git a/problems/create-a-session-bar-chart/mysql_schemas.sql b/problems/create-a-session-bar-chart/mysql_schemas.sql
deleted file mode 100644
index 6041cffa5..000000000
--- a/problems/create-a-session-bar-chart/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Sessions (session_id int, duration int);
-Truncate table Sessions;
-insert into Sessions (session_id, duration) values ('1', '30');
-insert into Sessions (session_id, duration) values ('2', '199');
-insert into Sessions (session_id, duration) values ('3', '299');
-insert into Sessions (session_id, duration) values ('4', '580');
-insert into Sessions (session_id, duration) values ('5', '1000');
diff --git a/problems/create-maximum-number/README.md b/problems/create-maximum-number/README.md
deleted file mode 100644
index a556c1b4b..000000000
--- a/problems/create-maximum-number/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../generalized-abbreviation "Generalized Abbreviation")
-　　　　　　　　　　　　　　　　
-[Next >](../coin-change "Coin Change")
-
-## [321. Create Maximum Number (Hard)](https://leetcode.com/problems/create-maximum-number "拼接最大数")
-
-<p>You are given two integer arrays <code>nums1</code> and <code>nums2</code> of lengths <code>m</code> and <code>n</code> respectively. <code>nums1</code> and <code>nums2</code> represent the digits of two numbers. You are also given an integer <code>k</code>.</p>
-
-<p>Create the maximum number of length <code>k &lt;= m + n</code> from digits of the two numbers. The relative order of the digits from the same array must be preserved.</p>
-
-<p>Return an array of the <code>k</code> digits representing the answer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [3,4,6,5], nums2 = [9,1,2,5,8,3], k = 5
-<strong>Output:</strong> [9,8,6,5,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [6,7], nums2 = [6,0,4], k = 5
-<strong>Output:</strong> [6,7,6,0,4]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [3,9], nums2 = [8,9], k = 3
-<strong>Output:</strong> [9,8,9]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == nums1.length</code></li>
-	<li><code>n == nums2.length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 500</code></li>
-	<li><code>0 &lt;= nums1[i], nums2[i] &lt;= 9</code></li>
-	<li><code>1 &lt;= k &lt;= m + n</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Remove K Digits](../remove-k-digits) (Medium)
-  1. [Maximum Swap](../maximum-swap) (Medium)
diff --git a/problems/create-maximum-number/create_maximum_number.go b/problems/create-maximum-number/create_maximum_number.go
deleted file mode 100644
index 1147526b1..000000000
--- a/problems/create-maximum-number/create_maximum_number.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem321
diff --git a/problems/create-maximum-number/create_maximum_number_test.go b/problems/create-maximum-number/create_maximum_number_test.go
deleted file mode 100644
index 1147526b1..000000000
--- a/problems/create-maximum-number/create_maximum_number_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem321
diff --git a/problems/create-sorted-array-through-instructions/README.md b/problems/create-sorted-array-through-instructions/README.md
deleted file mode 100644
index 7143b44aa..000000000
--- a/problems/create-sorted-array-through-instructions/README.md
+++ /dev/null
@@ -1,97 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sell-diminishing-valued-colored-balls "Sell Diminishing-Valued Colored Balls")
-　　　　　　　　　　　　　　　　
-[Next >](../lowest-common-ancestor-of-a-binary-tree-iii "Lowest Common Ancestor of a Binary Tree III")
-
-## [1649. Create Sorted Array through Instructions (Hard)](https://leetcode.com/problems/create-sorted-array-through-instructions "通过指令创建有序数组")
-
-<p>Given an integer array <code>instructions</code>, you are asked to create a sorted array from the elements in <code>instructions</code>. You start with an empty container <code>nums</code>. For each element from <strong>left to right</strong> in <code>instructions</code>, insert it into <code>nums</code>. The <strong>cost</strong> of each insertion is the <b>minimum</b> of the following:</p>
-
-<ul>
-	<li>The number of elements currently in <code>nums</code> that are <strong>strictly less than</strong> <code>instructions[i]</code>.</li>
-	<li>The number of elements currently in <code>nums</code> that are <strong>strictly greater than</strong> <code>instructions[i]</code>.</li>
-</ul>
-
-<p>For example, if inserting element <code>3</code> into <code>nums = [1,2,3,5]</code>, the <strong>cost</strong> of insertion is <code>min(2, 1)</code> (elements <code>1</code> and <code>2</code> are less than <code>3</code>, element <code>5</code> is greater than <code>3</code>) and <code>nums</code> will become <code>[1,2,3,3,5]</code>.</p>
-
-<p>Return <em>the <strong>total cost</strong> to insert all elements from </em><code>instructions</code><em> into </em><code>nums</code>. Since the answer may be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> instructions = [1,5,6,2]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Begin with nums = [].
-Insert 1 with cost min(0, 0) = 0, now nums = [1].
-Insert 5 with cost min(1, 0) = 0, now nums = [1,5].
-Insert 6 with cost min(2, 0) = 0, now nums = [1,5,6].
-Insert 2 with cost min(1, 2) = 1, now nums = [1,2,5,6].
-The total cost is 0 + 0 + 0 + 1 = 1.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> instructions = [1,2,3,6,5,4]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Begin with nums = [].
-Insert 1 with cost min(0, 0) = 0, now nums = [1].
-Insert 2 with cost min(1, 0) = 0, now nums = [1,2].
-Insert 3 with cost min(2, 0) = 0, now nums = [1,2,3].
-Insert 6 with cost min(3, 0) = 0, now nums = [1,2,3,6].
-Insert 5 with cost min(3, 1) = 1, now nums = [1,2,3,5,6].
-Insert 4 with cost min(3, 2) = 2, now nums = [1,2,3,4,5,6].
-The total cost is 0 + 0 + 0 + 0 + 1 + 2 = 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> instructions = [1,3,3,3,2,4,2,1,2]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Begin with nums = [].
-Insert 1 with cost min(0, 0) = 0, now nums = [1].
-Insert 3 with cost min(1, 0) = 0, now nums = [1,3].
-Insert 3 with cost min(1, 0) = 0, now nums = [1,3,3].
-Insert 3 with cost min(1, 0) = 0, now nums = [1,3,3,3].
-Insert 2 with cost min(1, 3) = 1, now nums = [1,2,3,3,3].
-Insert 4 with cost min(5, 0) = 0, now nums = [1,2,3,3,3,4].
-​​​​​​​Insert 2 with cost min(1, 4) = 1, now nums = [1,2,2,3,3,3,4].
-​​​​​​​Insert 1 with cost min(0, 6) = 0, now nums = [1,1,2,2,3,3,3,4].
-​​​​​​​Insert 2 with cost min(2, 4) = 2, now nums = [1,1,2,2,2,3,3,3,4].
-The total cost is 0 + 0 + 0 + 0 + 1 + 0 + 1 + 0 + 2 = 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= instructions.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= instructions[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Merge Sort](../../tag/merge-sort/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-This problem is closely related to finding the number of inversions in an array
-</details>
-
-<details>
-<summary>Hint 2</summary>
-if i know the position in which i will insert the i-th element in I can find the minimum cost to insert it
-</details>
diff --git a/problems/create-target-array-in-the-given-order/README.md b/problems/create-target-array-in-the-given-order/README.md
deleted file mode 100644
index ed80d4212..000000000
--- a/problems/create-target-array-in-the-given-order/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pizza-with-3n-slices "Pizza With 3n Slices")
-　　　　　　　　　　　　　　　　
-[Next >](../four-divisors "Four Divisors")
-
-## [1389. Create Target Array in the Given Order (Easy)](https://leetcode.com/problems/create-target-array-in-the-given-order "按既定顺序创建目标数组")
-
-<p>Given two arrays of integers&nbsp;<code>nums</code> and <code>index</code>. Your task is to create <em>target</em> array under the following rules:</p>
-
-<ul>
-	<li>Initially <em>target</em> array is empty.</li>
-	<li>From left to right read nums[i] and index[i], insert at index <code>index[i]</code>&nbsp;the value <code>nums[i]</code>&nbsp;in&nbsp;<em>target</em> array.</li>
-	<li>Repeat the previous step until there are no elements to read in <code>nums</code> and <code>index.</code></li>
-</ul>
-
-<p>Return the <em>target</em> array.</p>
-
-<p>It is guaranteed that the insertion operations will be valid.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,2,3,4], index = [0,1,2,2,1]
-<strong>Output:</strong> [0,4,1,3,2]
-<strong>Explanation:</strong>
-nums       index     target
-0            0        [0]
-1            1        [0,1]
-2            2        [0,1,2]
-3            2        [0,1,3,2]
-4            1        [0,4,1,3,2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,0], index = [0,1,2,3,0]
-<strong>Output:</strong> [0,1,2,3,4]
-<strong>Explanation:</strong>
-nums       index     target
-1            0        [1]
-2            1        [1,2]
-3            2        [1,2,3]
-4            3        [1,2,3,4]
-0            0        [0,1,2,3,4]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1], index = [0]
-<strong>Output:</strong> [1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length, index.length &lt;= 100</code></li>
-	<li><code>nums.length == index.length</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 100</code></li>
-	<li><code>0 &lt;= index[i] &lt;= i</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process and fill corresponding numbers in the designated spots.
-</details>
diff --git a/problems/create-target-array-in-the-given-order/create_target_array_in_the_given_order.go b/problems/create-target-array-in-the-given-order/create_target_array_in_the_given_order.go
deleted file mode 100644
index cf70a3f4a..000000000
--- a/problems/create-target-array-in-the-given-order/create_target_array_in_the_given_order.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem1389
-
-func createTargetArray(nums []int, index []int) []int {
-	ans := make([]int, len(nums))
-	for i, idx := range index {
-		copy(ans[idx+1:], ans[idx:])
-		ans[idx] = nums[i]
-	}
-	return ans
-}
diff --git a/problems/create-target-array-in-the-given-order/create_target_array_in_the_given_order_test.go b/problems/create-target-array-in-the-given-order/create_target_array_in_the_given_order_test.go
deleted file mode 100644
index 8fa361251..000000000
--- a/problems/create-target-array-in-the-given-order/create_target_array_in_the_given_order_test.go
+++ /dev/null
@@ -1,38 +0,0 @@
-package problem1389
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in    []int
-	index []int
-	want  []int
-}
-
-func TestCreateTargetArray(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:    []int{0, 1, 2, 3, 4},
-			index: []int{0, 1, 2, 2, 1},
-			want:  []int{0, 4, 1, 3, 2},
-		},
-		{
-			in:    []int{1, 2, 3, 4, 0},
-			index: []int{0, 1, 2, 3, 0},
-			want:  []int{0, 1, 2, 3, 4},
-		},
-		{
-			in:    []int{1},
-			index: []int{0},
-			want:  []int{1},
-		},
-	}
-	for _, tt := range tests {
-		got := createTargetArray(tt.in, tt.index)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/critical-connections-in-a-network/README.md b/problems/critical-connections-in-a-network/README.md
deleted file mode 100644
index 244ee23af..000000000
--- a/problems/critical-connections-in-a-network/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-concatenation-maximum-sum "K-Concatenation Maximum Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../monthly-transactions-i "Monthly Transactions I")
-
-## [1192. Critical Connections in a Network (Hard)](https://leetcode.com/problems/critical-connections-in-a-network "查找集群内的「关键连接」")
-
-<p>There are <code>n</code> servers numbered from <code>0</code> to <code>n - 1</code> connected by undirected server-to-server <code>connections</code> forming a network where <code>connections[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> represents a connection between servers <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code>. Any server can reach other servers directly or indirectly through the network.</p>
-
-<p>A <em>critical connection</em> is a connection that, if removed, will make some servers unable to reach some other server.</p>
-
-<p>Return all critical connections in the network in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/09/03/1537_ex1_2.png" style="width: 198px; height: 248px;" />
-<pre>
-<strong>Input:</strong> n = 4, connections = [[0,1],[1,2],[2,0],[1,3]]
-<strong>Output:</strong> [[1,3]]
-<strong>Explanation:</strong> [[3,1]] is also accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, connections = [[0,1]]
-<strong>Output:</strong> [[0,1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>n - 1 &lt;= connections.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-	<li>There are no repeated connections.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Biconnected Component](../../tag/biconnected-component/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use Tarjan's algorithm.
-</details>
diff --git a/problems/custom-sort-string/README.md b/problems/custom-sort-string/README.md
deleted file mode 100644
index 6a34c35cf..000000000
--- a/problems/custom-sort-string/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../domino-and-tromino-tiling "Domino and Tromino Tiling")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-matching-subsequences "Number of Matching Subsequences")
-
-## [791. Custom Sort String (Medium)](https://leetcode.com/problems/custom-sort-string "自定义字符串排序")
-
-<p>You are given two strings order and s. All the words of <code>order</code> are <strong>unique</strong> and were sorted in some custom order previously.</p>
-
-<p>Permute the characters of <code>s</code> so that they match the order that <code>order</code> was sorted. More specifically, if a character <code>x</code> occurs before a character <code>y</code> in <code>order</code>, then <code>x</code> should occur before <code>y</code> in the permuted string.</p>
-
-<p>Return <em>any permutation of </em><code>s</code><em> that satisfies this property</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> order = &quot;cba&quot;, s = &quot;abcd&quot;
-<strong>Output:</strong> &quot;cbad&quot;
-<strong>Explanation:</strong> 
-&quot;a&quot;, &quot;b&quot;, &quot;c&quot; appear in order, so the order of &quot;a&quot;, &quot;b&quot;, &quot;c&quot; should be &quot;c&quot;, &quot;b&quot;, and &quot;a&quot;. 
-Since &quot;d&quot; does not appear in order, it can be at any position in the returned string. &quot;dcba&quot;, &quot;cdba&quot;, &quot;cbda&quot; are also valid outputs.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> order = &quot;cbafg&quot;, s = &quot;abcd&quot;
-<strong>Output:</strong> &quot;cbad&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= order.length &lt;= 26</code></li>
-	<li><code>1 &lt;= s.length &lt;= 200</code></li>
-	<li><code>order</code> and <code>s</code> consist of lowercase English letters.</li>
-	<li>All the characters of <code>order</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/custom-sort-string/custom_sort_string.go b/problems/custom-sort-string/custom_sort_string.go
deleted file mode 100644
index c266bb28b..000000000
--- a/problems/custom-sort-string/custom_sort_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem791
diff --git a/problems/custom-sort-string/custom_sort_string_test.go b/problems/custom-sort-string/custom_sort_string_test.go
deleted file mode 100644
index c266bb28b..000000000
--- a/problems/custom-sort-string/custom_sort_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem791
diff --git a/problems/customer-order-frequency/README.md b/problems/customer-order-frequency/README.md
deleted file mode 100644
index c683e39f5..000000000
--- a/problems/customer-order-frequency/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stone-game-iv "Stone Game IV")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-good-pairs "Number of Good Pairs")
-
-## [1511. Customer Order Frequency (Easy)](https://leetcode.com/problems/customer-order-frequency "消费者下单频率")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/customer-order-frequency/mysql_schemas.sql b/problems/customer-order-frequency/mysql_schemas.sql
deleted file mode 100644
index 307de3f82..000000000
--- a/problems/customer-order-frequency/mysql_schemas.sql
+++ /dev/null
@@ -1,23 +0,0 @@
-Create table If Not Exists Customers (customer_id int, name varchar(30), country varchar(30));
-Create table If Not Exists Product (product_id int, description varchar(30), price int)
-;
-Create table If Not Exists Orders (order_id int, customer_id int, product_id int, order_date date, quantity int)
-;
-Truncate table Customers;
-insert into Customers (customer_id, name, country) values ('1', 'Winston', 'USA');
-insert into Customers (customer_id, name, country) values ('2', 'Jonathan', 'Peru');
-insert into Customers (customer_id, name, country) values ('3', 'Moustafa', 'Egypt');
-Truncate table Product;
-insert into Product (product_id, description, price) values ('10', 'LC Phone', '300');
-insert into Product (product_id, description, price) values ('20', 'LC T-Shirt', '10');
-insert into Product (product_id, description, price) values ('30', 'LC Book', '45');
-insert into Product (product_id, description, price) values ('40', 'LC Keychain', '2');
-Truncate table Orders;
-insert into Orders (order_id, customer_id, product_id, order_date, quantity) values ('1', '1', '10', '2020-06-10', '1');
-insert into Orders (order_id, customer_id, product_id, order_date, quantity) values ('2', '1', '20', '2020-07-01', '1');
-insert into Orders (order_id, customer_id, product_id, order_date, quantity) values ('3', '1', '30', '2020-07-08', '2');
-insert into Orders (order_id, customer_id, product_id, order_date, quantity) values ('4', '2', '10', '2020-06-15', '2');
-insert into Orders (order_id, customer_id, product_id, order_date, quantity) values ('5', '2', '40', '2020-07-01', '10');
-insert into Orders (order_id, customer_id, product_id, order_date, quantity) values ('6', '3', '20', '2020-06-24', '2');
-insert into Orders (order_id, customer_id, product_id, order_date, quantity) values ('7', '3', '30', '2020-06-25', '2');
-insert into Orders (order_id, customer_id, product_id, order_date, quantity) values ('9', '3', '30', '2020-05-08', '3');
diff --git a/problems/customer-placing-the-largest-number-of-orders/README.md b/problems/customer-placing-the-largest-number-of-orders/README.md
deleted file mode 100644
index e00893cb3..000000000
--- a/problems/customer-placing-the-largest-number-of-orders/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../investments-in-2016 "Investments in 2016")
-　　　　　　　　　　　　　　　　
-[Next >](../erect-the-fence "Erect the Fence")
-
-## [586. Customer Placing the Largest Number of Orders (Easy)](https://leetcode.com/problems/customer-placing-the-largest-number-of-orders "订单最多的客户")
-
-<p>Query the <b>customer_number</b> from the <b><i>orders</i></b> table for the customer who has placed the largest number of orders.</p>
-
-<p>It is guaranteed that exactly one customer will have placed more orders than any other customer.</p>
-
-<p>The <b><i>orders</i></b> table is defined as follows:</p>
-
-<pre>
-| Column            | Type      |
-|-------------------|-----------|
-| order_number (PK) | int       |
-| customer_number   | int       |
-| order_date        | date      |
-| required_date     | date      |
-| shipped_date      | date      |
-| status            | char(15)  |
-| comment           | char(200) |
-</pre>
-
-<p><b>Sample Input</b></p>
-
-<pre>
-| order_number | customer_number | order_date | required_date | shipped_date | status | comment |
-|--------------|-----------------|------------|---------------|--------------|--------|---------|
-| 1            | 1               | 2017-04-09 | 2017-04-13    | 2017-04-12   | Closed |         |
-| 2            | 2               | 2017-04-15 | 2017-04-20    | 2017-04-18   | Closed |         |
-| 3            | 3               | 2017-04-16 | 2017-04-25    | 2017-04-20   | Closed |         |
-| 4            | 3               | 2017-04-18 | 2017-04-28    | 2017-04-25   | Closed |         |
-</pre>
-
-<p><b>Sample Output</b></p>
-
-<pre>
-| customer_number |
-|-----------------|
-| 3               |
-</pre>
-
-<p><b>Explanation</b></p>
-
-<pre>
-The customer with number &#39;3&#39; has two orders, which is greater than either customer &#39;1&#39; or &#39;2&#39; because each of them  only has one order. 
-So the result is customer_number &#39;3&#39;.
-</pre>
-
-<p><i><b>Follow up:</b> What if more than one customer have the largest number of orders, can you find all the customer_number in this case?</i></p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-MySQL uses a different expression to get the first records other than MSSQL's TOP expression.
-</details>
diff --git a/problems/customer-placing-the-largest-number-of-orders/customer_placing_the_largest_number_of_orders.sql b/problems/customer-placing-the-largest-number-of-orders/customer_placing_the_largest_number_of_orders.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/customer-placing-the-largest-number-of-orders/customer_placing_the_largest_number_of_orders.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/customer-placing-the-largest-number-of-orders/mysql_schemas.sql b/problems/customer-placing-the-largest-number-of-orders/mysql_schemas.sql
deleted file mode 100644
index 989cb5c24..000000000
--- a/problems/customer-placing-the-largest-number-of-orders/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists orders (order_number int, customer_number int);
-Truncate table orders;
-insert into orders (order_number, customer_number) values ('1', '1');
-insert into orders (order_number, customer_number) values ('2', '2');
-insert into orders (order_number, customer_number) values ('3', '3');
-insert into orders (order_number, customer_number) values ('4', '3');
diff --git a/problems/customer-who-visited-but-did-not-make-any-transactions/README.md b/problems/customer-who-visited-but-did-not-make-any-transactions/README.md
deleted file mode 100644
index c37bf735d..000000000
--- a/problems/customer-who-visited-but-did-not-make-any-transactions/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../put-boxes-into-the-warehouse-ii "Put Boxes Into the Warehouse II")
-　　　　　　　　　　　　　　　　
-[Next >](../special-positions-in-a-binary-matrix "Special Positions in a Binary Matrix")
-
-## [1581. Customer Who Visited but Did Not Make Any Transactions (Easy)](https://leetcode.com/problems/customer-who-visited-but-did-not-make-any-transactions "进店却未进行过交易的顾客")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Sellers With No Sales](../sellers-with-no-sales) (Easy)
diff --git a/problems/customer-who-visited-but-did-not-make-any-transactions/mysql_schemas.sql b/problems/customer-who-visited-but-did-not-make-any-transactions/mysql_schemas.sql
deleted file mode 100644
index 9f6c0ba5c..000000000
--- a/problems/customer-who-visited-but-did-not-make-any-transactions/mysql_schemas.sql
+++ /dev/null
@@ -1,16 +0,0 @@
-Create table If Not Exists Visits(visit_id int, customer_id int);
-Create table If Not Exists Transactions(transaction_id int, visit_id int, amount int);
-Truncate table Visits;
-insert into Visits (visit_id, customer_id) values ('1', '23');
-insert into Visits (visit_id, customer_id) values ('2', '9');
-insert into Visits (visit_id, customer_id) values ('4', '30');
-insert into Visits (visit_id, customer_id) values ('5', '54');
-insert into Visits (visit_id, customer_id) values ('6', '96');
-insert into Visits (visit_id, customer_id) values ('7', '54');
-insert into Visits (visit_id, customer_id) values ('8', '54');
-Truncate table Transactions;
-insert into Transactions (transaction_id, visit_id, amount) values ('2', '5', '310');
-insert into Transactions (transaction_id, visit_id, amount) values ('3', '5', '300');
-insert into Transactions (transaction_id, visit_id, amount) values ('9', '5', '200');
-insert into Transactions (transaction_id, visit_id, amount) values ('12', '1', '910');
-insert into Transactions (transaction_id, visit_id, amount) values ('13', '2', '970');
diff --git a/problems/customers-who-bought-all-products/README.md b/problems/customers-who-bought-all-products/README.md
deleted file mode 100644
index 1f081037c..000000000
--- a/problems/customers-who-bought-all-products/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-duplicate-substring "Longest Duplicate Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../last-stone-weight "Last Stone Weight")
-
-## [1045. Customers Who Bought All Products (Medium)](https://leetcode.com/problems/customers-who-bought-all-products "买下所有产品的客户")
-
-<p>Table:&nbsp;<code>Customer</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| customer_id | int     |
-| product_key | int     |
-+-------------+---------+
-product_key is a foreign key to <code>Product</code> table.
-</pre>
-
-<p>Table:&nbsp;<code>Product</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| product_key | int     |
-+-------------+---------+
-product_key is the primary key column for this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query for a report that provides the customer ids from the&nbsp;<code>Customer</code>&nbsp;table&nbsp;that bought all the products in the <code>Product</code>&nbsp;table.</p>
-
-<p>For example:</p>
-
-<pre>
-Customer table:
-+-------------+-------------+
-| customer_id | product_key |
-+-------------+-------------+
-| 1           | 5           |
-| 2           | 6           |
-| 3           | 5           |
-| 3           | 6           |
-| 1           | 6           |
-+-------------+-------------+
-
-Product table:
-+-------------+
-| product_key |
-+-------------+
-| 5           |
-| 6           |
-+-------------+
-
-Result table:
-+-------------+
-| customer_id |
-+-------------+
-| 1           |
-| 3           |
-+-------------+
-The customers who bought all the products (5 and 6) are customers with id 1 and 3.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/customers-who-bought-all-products/customers_who_bought_all_products.sql b/problems/customers-who-bought-all-products/customers_who_bought_all_products.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/customers-who-bought-all-products/customers_who_bought_all_products.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/customers-who-bought-all-products/mysql_schemas.sql b/problems/customers-who-bought-all-products/mysql_schemas.sql
deleted file mode 100644
index ef68a04c1..000000000
--- a/problems/customers-who-bought-all-products/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Customer (customer_id int, product_key int);
-Create table Product (product_key int);
-Truncate table Customer;
-insert into Customer (customer_id, product_key) values ('1', '5');
-insert into Customer (customer_id, product_key) values ('2', '6');
-insert into Customer (customer_id, product_key) values ('3', '5');
-insert into Customer (customer_id, product_key) values ('3', '6');
-insert into Customer (customer_id, product_key) values ('1', '6');
-Truncate table Product;
-insert into Product (product_key) values ('5');
-insert into Product (product_key) values ('6');
diff --git a/problems/customers-who-bought-products-a-and-b-but-not-c/README.md b/problems/customers-who-bought-products-a-and-b-but-not-c/README.md
deleted file mode 100644
index 443bb7664..000000000
--- a/problems/customers-who-bought-products-a-and-b-but-not-c/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-all-good-strings "Find All Good Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../count-largest-group "Count Largest Group")
-
-## [1398. Customers Who Bought Products A and B but Not C (Medium)](https://leetcode.com/problems/customers-who-bought-products-a-and-b-but-not-c "购买了产品 A 和产品 B 却没有购买产品 C 的顾客")
-
-<p>Table: <code>Customers</code></p>
-<pre>
-+---------------------+---------+
-| Column Name         | Type    |
-+---------------------+---------+
-| customer_id         | int     |
-| customer_name       | varchar |
-+---------------------+---------+
-customer_id is the primary key for this table.
-customer_name is the name of the customer.
-</pre>
- 
-<p>Table: <code>Orders</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| order_id      | int     |
-| customer_id   | int     |
-| product_name  | varchar |
-+---------------+---------+
-order_id is the primary key for this table.
-customer_id is the id of the customer who bought the product "product_name".
-</pre>
- 
-Write an SQL query to report the customer_id and customer_name of customers who bought products "A", "B" but did not buy the product "C" since we want to recommend them buy this product.
-
-Return the result table ordered by customer_id.
-
-The query result format is in the following example.
-
-<pre>
-Customers table:
-+-------------+---------------+
-| customer_id | customer_name |
-+-------------+---------------+
-| 1           | Daniel        |
-| 2           | Diana         |
-| 3           | Elizabeth     |
-| 4           | Jhon          |
-+-------------+---------------+
-
-Orders table:
-+------------+--------------+---------------+
-| order_id   | customer_id  | product_name  |
-+------------+--------------+---------------+
-| 10         |     1        |     A         |
-| 20         |     1        |     B         |
-| 30         |     1        |     D         |
-| 40         |     1        |     C         |
-| 50         |     2        |     A         |
-| 60         |     3        |     A         |
-| 70         |     3        |     B         |
-| 80         |     3        |     D         |
-| 90         |     4        |     C         |
-+------------+--------------+---------------+
-
-Result table:
-+-------------+---------------+
-| customer_id | customer_name |
-+-------------+---------------+
-| 3           | Elizabeth     |
-+-------------+---------------+
-Only the customer_id with id 3 bought the product A and B but not the product C.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/customers-who-bought-products-a-and-b-but-not-c/mysql_schemas.sql b/problems/customers-who-bought-products-a-and-b-but-not-c/mysql_schemas.sql
deleted file mode 100644
index a69fad8cb..000000000
--- a/problems/customers-who-bought-products-a-and-b-but-not-c/mysql_schemas.sql
+++ /dev/null
@@ -1,17 +0,0 @@
-Create table If Not Exists Customers (customer_id int, customer_name varchar(30));
-Create table If Not Exists Orders (order_id int, customer_id int, product_name varchar(30));
-Truncate table Customers;
-insert into Customers (customer_id, customer_name) values ('1', 'Daniel');
-insert into Customers (customer_id, customer_name) values ('2', 'Diana');
-insert into Customers (customer_id, customer_name) values ('3', 'Elizabeth');
-insert into Customers (customer_id, customer_name) values ('4', 'Jhon');
-Truncate table Orders;
-insert into Orders (order_id, customer_id, product_name) values ('10', '1', 'A');
-insert into Orders (order_id, customer_id, product_name) values ('20', '1', 'B');
-insert into Orders (order_id, customer_id, product_name) values ('30', '1', 'D');
-insert into Orders (order_id, customer_id, product_name) values ('40', '1', 'C');
-insert into Orders (order_id, customer_id, product_name) values ('50', '2', 'A');
-insert into Orders (order_id, customer_id, product_name) values ('60', '3', 'A');
-insert into Orders (order_id, customer_id, product_name) values ('70', '3', 'B');
-insert into Orders (order_id, customer_id, product_name) values ('80', '3', 'D');
-insert into Orders (order_id, customer_id, product_name) values ('90', '4', 'C');
diff --git a/problems/customers-who-never-order/README.md b/problems/customers-who-never-order/README.md
deleted file mode 100644
index 470908e17..000000000
--- a/problems/customers-who-never-order/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../duplicate-emails "Duplicate Emails")
-　　　　　　　　　　　　　　　　
-[Next >](../department-highest-salary "Department Highest Salary")
-
-## [183. Customers Who Never Order (Easy)](https://leetcode.com/problems/customers-who-never-order "从不订购的客户")
-
-<p>Table: <code>Customers</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| id          | int     |
-| name        | varchar |
-+-------------+---------+
-id is the primary key column for this table.
-Each row of this table indicates the ID and name of a customer.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Table: <code>Orders</code></p>
-
-<pre>
-+-------------+------+
-| Column Name | Type |
-+-------------+------+
-| id          | int  |
-| customerId  | int  |
-+-------------+------+
-id is the primary key column for this table.
-customerId is a foreign key of the ID from the Customers table.
-Each row of this table indicates the ID of an order and the ID of the customer who ordered it.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to report all customers who never order anything.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Customers table:
-+----+-------+
-| id | name  |
-+----+-------+
-| 1  | Joe   |
-| 2  | Henry |
-| 3  | Sam   |
-| 4  | Max   |
-+----+-------+
-Orders table:
-+----+------------+
-| id | customerId |
-+----+------------+
-| 1  | 3          |
-| 2  | 1          |
-+----+------------+
-<strong>Output:</strong> 
-+-----------+
-| Customers |
-+-----------+
-| Henry     |
-| Max       |
-+-----------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/customers-who-never-order/customers_who_never_order.sql b/problems/customers-who-never-order/customers_who_never_order.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/customers-who-never-order/customers_who_never_order.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/customers-who-never-order/mysql_schemas.sql b/problems/customers-who-never-order/mysql_schemas.sql
deleted file mode 100644
index 9a38db656..000000000
--- a/problems/customers-who-never-order/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Customers (id int, name varchar(255));
-Create table If Not Exists Orders (id int, customerId int);
-Truncate table Customers;
-insert into Customers (id, name) values ('1', 'Joe');
-insert into Customers (id, name) values ('2', 'Henry');
-insert into Customers (id, name) values ('3', 'Sam');
-insert into Customers (id, name) values ('4', 'Max');
-Truncate table Orders;
-insert into Orders (id, customerId) values ('1', '3');
-insert into Orders (id, customerId) values ('2', '1');
diff --git a/problems/cut-off-trees-for-golf-event/README.md b/problems/cut-off-trees-for-golf-event/README.md
deleted file mode 100644
index 355e1a9d3..000000000
--- a/problems/cut-off-trees-for-golf-event/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-continuous-increasing-subsequence "Longest Continuous Increasing Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../implement-magic-dictionary "Implement Magic Dictionary")
-
-## [675. Cut Off Trees for Golf Event (Hard)](https://leetcode.com/problems/cut-off-trees-for-golf-event "为高尔夫比赛砍树")
-
-<p>You are asked to cut off all the trees in a forest for a golf event. The forest is represented as an <code>m x n</code> matrix. In this matrix:</p>
-
-<ul>
-	<li><code>0</code> means the cell cannot be walked through.</li>
-	<li><code>1</code> represents an empty cell that can be walked through.</li>
-	<li>A number greater than <code>1</code> represents a tree in a cell that can be walked through, and this number is the tree&#39;s height.</li>
-</ul>
-
-<p>In one step, you can walk in any of the four directions: north, east, south, and west. If you are standing in a cell with a tree, you can choose whether to cut it off.</p>
-
-<p>You must cut off the trees in order from shortest to tallest. When you cut off a tree, the value at its cell becomes <code>1</code> (an empty cell).</p>
-
-<p>Starting from the point <code>(0, 0)</code>, return <em>the minimum steps you need to walk to cut off all the trees</em>. If you cannot cut off all the trees, return <code>-1</code>.</p>
-
-<p>You are guaranteed that no two trees have the same height, and there is at least one tree needs to be cut off.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/26/trees1.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> forest = [[1,2,3],[0,0,4],[7,6,5]]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Following the path above allows you to cut off the trees from shortest to tallest in 6 steps.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/26/trees2.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> forest = [[1,2,3],[0,0,0],[7,6,5]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> The trees in the bottom row cannot be accessed as the middle row is blocked.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> forest = [[2,3,4],[0,0,5],[8,7,6]]
-<strong>Output:</strong> 6
-<b>Explanation:</b> You can follow the same path as Example 1 to cut off all the trees.
-Note that you can cut off the first tree at (0, 0) before making any steps.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == forest.length</code></li>
-	<li><code>n == forest[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>0 &lt;= forest[i][j] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
diff --git a/problems/cut-off-trees-for-golf-event/cut_off_trees_for_golf_event.go b/problems/cut-off-trees-for-golf-event/cut_off_trees_for_golf_event.go
deleted file mode 100644
index 0578a7546..000000000
--- a/problems/cut-off-trees-for-golf-event/cut_off_trees_for_golf_event.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem675
diff --git a/problems/cut-off-trees-for-golf-event/cut_off_trees_for_golf_event_test.go b/problems/cut-off-trees-for-golf-event/cut_off_trees_for_golf_event_test.go
deleted file mode 100644
index 0578a7546..000000000
--- a/problems/cut-off-trees-for-golf-event/cut_off_trees_for_golf_event_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem675
diff --git a/problems/cutting-ribbons/README.md b/problems/cutting-ribbons/README.md
deleted file mode 100644
index 6d7c7f13c..000000000
--- a/problems/cutting-ribbons/README.md
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-latest-login-in-2020 "The Latest Login in 2020")
-　　　　　　　　　　　　　　　　
-[Next >](../page-recommendations-ii "Page Recommendations II")
-
-## [1891. Cutting Ribbons (Medium)](https://leetcode.com/problems/cutting-ribbons "割绳子")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Capacity To Ship Packages Within D Days](../capacity-to-ship-packages-within-d-days) (Medium)
-  1. [Add Minimum Number of Rungs](../add-minimum-number-of-rungs) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use binary search on the answer.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can get l/m branches of length m from a branch with length l.
-</details>
diff --git a/problems/cyclically-rotating-a-grid/README.md b/problems/cyclically-rotating-a-grid/README.md
deleted file mode 100644
index bd3a7fc9f..000000000
--- a/problems/cyclically-rotating-a-grid/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-product-difference-between-two-pairs "Maximum Product Difference Between Two Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-wonderful-substrings "Number of Wonderful Substrings")
-
-## [1914. Cyclically Rotating a Grid (Medium)](https://leetcode.com/problems/cyclically-rotating-a-grid "循环轮转矩阵")
-
-<p>You are given an <code>m x n</code> integer matrix <code>grid</code>​​​, where <code>m</code> and <code>n</code> are both <strong>even</strong> integers, and an integer <code>k</code>.</p>
-
-<p>The matrix is composed of several layers, which is shown in the below image, where each color is its own layer:</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/06/10/ringofgrid.png" style="width: 231px; height: 258px;" /></p>
-
-<p>A cyclic rotation of the matrix is done by cyclically rotating <strong>each layer</strong> in the matrix. To cyclically rotate a layer once, each element in the layer will take the place of the adjacent element in the <strong>counter-clockwise</strong> direction. An example rotation is shown below:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/22/explanation_grid.jpg" style="width: 500px; height: 268px;" />
-<p>Return <em>the matrix after applying </em><code>k</code> <em>cyclic rotations to it</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/19/rod2.png" style="width: 421px; height: 191px;" />
-<pre>
-<strong>Input:</strong> grid = [[40,10],[30,20]], k = 1
-<strong>Output:</strong> [[10,20],[40,30]]
-<strong>Explanation:</strong> The figures above represent the grid at every state.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<strong><img alt="" src="https://assets.leetcode.com/uploads/2021/06/10/ringofgrid5.png" style="width: 231px; height: 262px;" /></strong> <strong><img alt="" src="https://assets.leetcode.com/uploads/2021/06/10/ringofgrid6.png" style="width: 231px; height: 262px;" /></strong> <strong><img alt="" src="https://assets.leetcode.com/uploads/2021/06/10/ringofgrid7.png" style="width: 231px; height: 262px;" /></strong>
-
-<pre>
-<strong>Input:</strong> grid = [[1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14,15,16]], k = 2
-<strong>Output:</strong> [[3,4,8,12],[2,11,10,16],[1,7,6,15],[5,9,13,14]]
-<strong>Explanation:</strong> The figures above represent the grid at every state.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>2 &lt;= m, n &lt;= 50</code></li>
-	<li>Both <code>m</code> and <code>n</code> are <strong>even</strong> integers.</li>
-	<li><code>1 &lt;= grid[i][j] &lt;=<sup> </sup>5000</code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First, you need to consider each layer separately as an array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Just cycle this array and then re-assign it.
-</details>
diff --git a/problems/daily-leads-and-partners/README.md b/problems/daily-leads-and-partners/README.md
deleted file mode 100644
index 299b0bd44..000000000
--- a/problems/daily-leads-and-partners/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-ways-to-distribute-candies "Count Ways to Distribute Candies")
-　　　　　　　　　　　　　　　　
-[Next >](../reformat-phone-number "Reformat Phone Number")
-
-## [1693. Daily Leads and Partners (Easy)](https://leetcode.com/problems/daily-leads-and-partners "每天的领导和合伙人")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/daily-leads-and-partners/mysql_schemas.sql b/problems/daily-leads-and-partners/mysql_schemas.sql
deleted file mode 100644
index 53e2eb911..000000000
--- a/problems/daily-leads-and-partners/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists DailySales(date_id date, make_name varchar(20), lead_id int, partner_id int);
-Truncate table DailySales;
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-8', 'toyota', '0', '1');
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-8', 'toyota', '1', '0');
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-8', 'toyota', '1', '2');
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-7', 'toyota', '0', '2');
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-7', 'toyota', '0', '1');
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-8', 'honda', '1', '2');
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-8', 'honda', '2', '1');
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-7', 'honda', '0', '1');
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-7', 'honda', '1', '2');
-insert into DailySales (date_id, make_name, lead_id, partner_id) values ('2020-12-7', 'honda', '2', '1');
diff --git a/problems/daily-temperatures/README.md b/problems/daily-temperatures/README.md
deleted file mode 100644
index ff6a70607..000000000
--- a/problems/daily-temperatures/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../monotone-increasing-digits "Monotone Increasing Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-and-earn "Delete and Earn")
-
-## [739. Daily Temperatures (Medium)](https://leetcode.com/problems/daily-temperatures "每日温度")
-
-<p>Given an array of integers <code>temperatures</code> represents the daily temperatures, return <em>an array</em> <code>answer</code> <em>such that</em> <code>answer[i]</code> <em>is the number of days you have to wait after the</em> <code>i<sup>th</sup></code> <em>day to get a warmer temperature</em>. If there is no future day for which this is possible, keep <code>answer[i] == 0</code> instead.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> temperatures = [73,74,75,71,69,72,76,73]
-<strong>Output:</strong> [1,1,4,2,1,1,0,0]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> temperatures = [30,40,50,60]
-<strong>Output:</strong> [1,1,1,0]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> temperatures = [30,60,90]
-<strong>Output:</strong> [1,1,0]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;temperatures.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>30 &lt;=&nbsp;temperatures[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Next Greater Element I](../next-greater-element-i) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the temperature is say, 70 today, then in the future a warmer temperature must be either 71, 72, 73, ..., 99, or 100.  We could remember when all of them occur next.
-</details>
diff --git a/problems/daily-temperatures/daily_temperatures.go b/problems/daily-temperatures/daily_temperatures.go
deleted file mode 100644
index e84a88c4f..000000000
--- a/problems/daily-temperatures/daily_temperatures.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem739
diff --git a/problems/daily-temperatures/daily_temperatures_test.go b/problems/daily-temperatures/daily_temperatures_test.go
deleted file mode 100644
index e84a88c4f..000000000
--- a/problems/daily-temperatures/daily_temperatures_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem739
diff --git a/problems/data-stream-as-disjoint-intervals/README.md b/problems/data-stream-as-disjoint-intervals/README.md
deleted file mode 100644
index 8bae905bf..000000000
--- a/problems/data-stream-as-disjoint-intervals/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../android-unlock-patterns "Android Unlock Patterns")
-　　　　　　　　　　　　　　　　
-[Next >](../design-snake-game "Design Snake Game")
-
-## [352. Data Stream as Disjoint Intervals (Hard)](https://leetcode.com/problems/data-stream-as-disjoint-intervals "将数据流变为多个不相交区间")
-
-<p>Given a data stream input of non-negative integers <code>a<sub>1</sub>, a<sub>2</sub>, ..., a<sub>n</sub></code>, summarize the numbers seen so far as a list of disjoint intervals.</p>
-
-<p>Implement the <code>SummaryRanges</code> class:</p>
-
-<ul>
-	<li><code>SummaryRanges()</code> Initializes the object with an empty stream.</li>
-	<li><code>void addNum(int val)</code> Adds the integer <code>val</code> to the stream.</li>
-	<li><code>int[][] getIntervals()</code> Returns a summary of the integers in the stream currently as a list of disjoint intervals <code>[start<sub>i</sub>, end<sub>i</sub>]</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;SummaryRanges&quot;, &quot;addNum&quot;, &quot;getIntervals&quot;, &quot;addNum&quot;, &quot;getIntervals&quot;, &quot;addNum&quot;, &quot;getIntervals&quot;, &quot;addNum&quot;, &quot;getIntervals&quot;, &quot;addNum&quot;, &quot;getIntervals&quot;]
-[[], [1], [], [3], [], [7], [], [2], [], [6], []]
-<strong>Output</strong>
-[null, null, [[1, 1]], null, [[1, 1], [3, 3]], null, [[1, 1], [3, 3], [7, 7]], null, [[1, 3], [7, 7]], null, [[1, 3], [6, 7]]]
-
-<strong>Explanation</strong>
-SummaryRanges summaryRanges = new SummaryRanges();
-summaryRanges.addNum(1);      // arr = [1]
-summaryRanges.getIntervals(); // return [[1, 1]]
-summaryRanges.addNum(3);      // arr = [1, 3]
-summaryRanges.getIntervals(); // return [[1, 1], [3, 3]]
-summaryRanges.addNum(7);      // arr = [1, 3, 7]
-summaryRanges.getIntervals(); // return [[1, 1], [3, 3], [7, 7]]
-summaryRanges.addNum(2);      // arr = [1, 2, 3, 7]
-summaryRanges.getIntervals(); // return [[1, 3], [7, 7]]
-summaryRanges.addNum(6);      // arr = [1, 2, 3, 6, 7]
-summaryRanges.getIntervals(); // return [[1, 3], [6, 7]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= val &lt;= 10<sup>4</sup></code></li>
-	<li>At most <code>3 * 10<sup>4</sup></code> calls will be made to <code>addNum</code> and <code>getIntervals</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> What if there are lots of merges and the number of disjoint intervals is small compared to the size of the data stream?</p>
-
-### Related Topics
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [Summary Ranges](../summary-ranges) (Easy)
-  1. [Find Right Interval](../find-right-interval) (Medium)
-  1. [Range Module](../range-module) (Hard)
diff --git a/problems/data-stream-as-disjoint-intervals/data_stream_as_disjoint_intervals.go b/problems/data-stream-as-disjoint-intervals/data_stream_as_disjoint_intervals.go
deleted file mode 100644
index 087d6216b..000000000
--- a/problems/data-stream-as-disjoint-intervals/data_stream_as_disjoint_intervals.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem352
diff --git a/problems/data-stream-as-disjoint-intervals/data_stream_as_disjoint_intervals_test.go b/problems/data-stream-as-disjoint-intervals/data_stream_as_disjoint_intervals_test.go
deleted file mode 100644
index 087d6216b..000000000
--- a/problems/data-stream-as-disjoint-intervals/data_stream_as_disjoint_intervals_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem352
diff --git a/problems/day-of-the-week/README.md b/problems/day-of-the-week/README.md
deleted file mode 100644
index 9ffca921a..000000000
--- a/problems/day-of-the-week/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distance-between-bus-stops "Distance Between Bus Stops")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-subarray-sum-with-one-deletion "Maximum Subarray Sum with One Deletion")
-
-## [1185. Day of the Week (Easy)](https://leetcode.com/problems/day-of-the-week "一周中的第几天")
-
-<p>Given a date, return the corresponding day of the week for that date.</p>
-
-<p>The input is given as three integers representing the <code>day</code>, <code>month</code> and <code>year</code> respectively.</p>
-
-<p>Return the answer as one of the following values&nbsp;<code>{&quot;Sunday&quot;, &quot;Monday&quot;, &quot;Tuesday&quot;, &quot;Wednesday&quot;, &quot;Thursday&quot;, &quot;Friday&quot;, &quot;Saturday&quot;}</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> day = 31, month = 8, year = 2019
-<strong>Output:</strong> &quot;Saturday&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> day = 18, month = 7, year = 1999
-<strong>Output:</strong> &quot;Sunday&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> day = 15, month = 8, year = 1993
-<strong>Output:</strong> &quot;Sunday&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The given dates are valid dates between the years <code>1971</code> and <code>2100</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sum up the number of days for the years before the given year.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Handle the case of a leap year.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Find the number of days for each month of the given year.
-</details>
diff --git a/problems/day-of-the-week/day_of_the_week.go b/problems/day-of-the-week/day_of_the_week.go
deleted file mode 100644
index 10218509e..000000000
--- a/problems/day-of-the-week/day_of_the_week.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package problem1185
-
-import "time"
-
-func dayOfTheWeek(day int, month int, year int) string {
-	return time.Date(year, time.Month(month), day, 0, 0, 0, 0, time.Local).
-		Weekday().
-		String()
-}
diff --git a/problems/day-of-the-week/day_of_the_week_test.go b/problems/day-of-the-week/day_of_the_week_test.go
deleted file mode 100644
index 1533f28e0..000000000
--- a/problems/day-of-the-week/day_of_the_week_test.go
+++ /dev/null
@@ -1,51 +0,0 @@
-package problem1185
-
-import "testing"
-
-type testType struct {
-	day   int
-	month int
-	year  int
-	want  string
-}
-
-func TestDayOfTheWeek(t *testing.T) {
-	tests := [...]testType{
-		{
-			day:   31,
-			month: 8,
-			year:  2019,
-			want:  "Saturday",
-		},
-		{
-			day:   15,
-			month: 8,
-			year:  1993,
-			want:  "Sunday",
-		},
-		{
-			day:   1,
-			month: 1,
-			year:  1970,
-			want:  "Thursday",
-		},
-		{
-			day:   25,
-			month: 3,
-			year:  1993,
-			want:  "Thursday",
-		},
-		{
-			day:   30,
-			month: 6,
-			year:  2000,
-			want:  "Friday",
-		},
-	}
-	for _, tt := range tests {
-		got := dayOfTheWeek(tt.day, tt.month, tt.year)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt, got, tt.want)
-		}
-	}
-}
diff --git a/problems/day-of-the-year/README.md b/problems/day-of-the-year/README.md
deleted file mode 100644
index 3f08074a0..000000000
--- a/problems/day-of-the-year/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../string-transforms-into-another-string "String Transforms Into Another String")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-dice-rolls-with-target-sum "Number of Dice Rolls With Target Sum")
-
-## [1154. Day of the Year (Easy)](https://leetcode.com/problems/day-of-the-year "一年中的第几天")
-
-<p>Given a string <code>date</code> representing a <a href="https://en.wikipedia.org/wiki/Gregorian_calendar" target="_blank">Gregorian calendar</a> date formatted as <code>YYYY-MM-DD</code>, return the day number of the year.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> date = &quot;2019-01-09&quot;
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> Given date is the 9th day of the year in 2019.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> date = &quot;2019-02-10&quot;
-<strong>Output:</strong> 41
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> date = &quot;2003-03-01&quot;
-<strong>Output:</strong> 60
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> date = &quot;2004-03-01&quot;
-<strong>Output:</strong> 61
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>date.length == 10</code></li>
-	<li><code>date[4] == date[7] == &#39;-&#39;</code>, and all other <code>date[i]</code>&#39;s are digits</li>
-	<li><code>date</code> represents a calendar date between Jan 1st, 1900 and Dec 31, 2019.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Have a integer array of how many days there are per month.  February gets one extra day if its a leap year.  Then, we can manually count the ordinal as day + (number of days in months before this one).
-</details>
diff --git a/problems/day-of-the-year/day_of_the_year.go b/problems/day-of-the-year/day_of_the_year.go
deleted file mode 100644
index 18df7e443..000000000
--- a/problems/day-of-the-year/day_of_the_year.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package problem1154
-
-import "time"
-
-func dayOfYear(date string) int {
-	t, _ := time.Parse("2006-01-02", date)
-	return t.YearDay()
-}
diff --git a/problems/day-of-the-year/day_of_the_year_test.go b/problems/day-of-the-year/day_of_the_year_test.go
deleted file mode 100644
index 607af2434..000000000
--- a/problems/day-of-the-year/day_of_the_year_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem1154
-
-import "testing"
-
-type testType struct {
-	in   string
-	want int
-}
-
-func TestDayOfYear(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "2019-01-09",
-			want: 9,
-		},
-		{
-			in:   "2019-02-10",
-			want: 41,
-		},
-		{
-			in:   "2003-03-01",
-			want: 60,
-		},
-		{
-			in:   "2004-03-01",
-			want: 61,
-		},
-		{
-			in:   "2000-08-01",
-			want: 214,
-		},
-		{
-			in:   "1993-12-11",
-			want: 345,
-		},
-	}
-	for _, tt := range tests {
-		got := dayOfYear(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/decode-string/README.md b/problems/decode-string/README.md
deleted file mode 100644
index 340d924ee..000000000
--- a/problems/decode-string/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../utf-8-validation "UTF-8 Validation")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-substring-with-at-least-k-repeating-characters "Longest Substring with At Least K Repeating Characters")
-
-## [394. Decode String (Medium)](https://leetcode.com/problems/decode-string "字符串解码")
-
-<p>Given an encoded string, return its decoded string.</p>
-
-<p>The encoding rule is: <code>k[encoded_string]</code>, where the <code>encoded_string</code> inside the square brackets is being repeated exactly <code>k</code> times. Note that <code>k</code> is guaranteed to be a positive integer.</p>
-
-<p>You may assume that the input string is always valid; No extra white spaces, square brackets are well-formed, etc.</p>
-
-<p>Furthermore, you may assume that the original data does not contain any digits and that digits are only for those repeat numbers, <code>k</code>. For example, there won&#39;t be input like <code>3a</code> or <code>2[4]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "3[a]2[bc]"
-<strong>Output:</strong> "aaabcbc"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "3[a2[c]]"
-<strong>Output:</strong> "accaccacc"
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s = "2[abc]3[cd]ef"
-<strong>Output:</strong> "abcabccdcdcdef"
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> s = "abc3[cd]xyz"
-<strong>Output:</strong> "abccdcdcdxyz"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 30</code></li>
-	<li><code>s</code> consists of lowercase English letters, digits, and square brackets <code>&#39;[]&#39;</code>.</li>
-	<li><code>s</code> is guaranteed to be <strong>a valid</strong> input.</li>
-	<li>All the integers in <code>s</code> are in the range <code>[1, 300]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Encode String with Shortest Length](../encode-string-with-shortest-length) (Hard)
-  1. [Number of Atoms](../number-of-atoms) (Hard)
-  1. [Brace Expansion](../brace-expansion) (Medium)
diff --git a/problems/decode-string/decode_string.go b/problems/decode-string/decode_string.go
deleted file mode 100644
index 2dfec0d61..000000000
--- a/problems/decode-string/decode_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem394
diff --git a/problems/decode-string/decode_string_test.go b/problems/decode-string/decode_string_test.go
deleted file mode 100644
index 2dfec0d61..000000000
--- a/problems/decode-string/decode_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem394
diff --git a/problems/decode-the-slanted-ciphertext/README.md b/problems/decode-the-slanted-ciphertext/README.md
deleted file mode 100644
index b6fac51a5..000000000
--- a/problems/decode-the-slanted-ciphertext/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-nodes-in-even-length-groups "Reverse Nodes in Even Length Groups")
-　　　　　　　　　　　　　　　　
-[Next >](../process-restricted-friend-requests "Process Restricted Friend Requests")
-
-## [2075. Decode the Slanted Ciphertext (Medium)](https://leetcode.com/problems/decode-the-slanted-ciphertext "解码斜向换位密码")
-
-<p>A string <code>originalText</code> is encoded using a <strong>slanted transposition cipher</strong> to a string <code>encodedText</code> with the help of a matrix having a <strong>fixed number of rows</strong> <code>rows</code>.</p>
-
-<p><code>originalText</code> is placed first in a top-left to bottom-right manner.</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/07/exa11.png" style="width: 300px; height: 185px;" />
-<p>The blue cells are filled first, followed by the red cells, then the yellow cells, and so on, until we reach the end of <code>originalText</code>. The arrow indicates the order in which the cells are filled. All empty cells are filled with <code>&#39; &#39;</code>. The number of columns is chosen such that the rightmost column will <strong>not be empty</strong> after filling in <code>originalText</code>.</p>
-
-<p><code>encodedText</code> is then formed by appending all characters of the matrix in a row-wise fashion.</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/07/exa12.png" style="width: 300px; height: 200px;" />
-<p>The characters in the blue cells are appended first to <code>encodedText</code>, then the red cells, and so on, and finally the yellow cells. The arrow indicates the order in which the cells are accessed.</p>
-
-<p>For example, if <code>originalText = &quot;cipher&quot;</code> and <code>rows = 3</code>, then we encode it in the following manner:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/25/desc2.png" style="width: 281px; height: 211px;" />
-<p>The blue arrows depict how <code>originalText</code> is placed in the matrix, and the red arrows denote the order in which <code>encodedText</code> is formed. In the above example, <code>encodedText = &quot;ch ie pr&quot;</code>.</p>
-
-<p>Given the encoded string <code>encodedText</code> and number of rows <code>rows</code>, return <em>the original string</em> <code>originalText</code>.</p>
-
-<p><strong>Note:</strong> <code>originalText</code> <strong>does not</strong> have any trailing spaces <code>&#39; &#39;</code>. The test cases are generated such that there is only one possible <code>originalText</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> encodedText = &quot;ch   ie   pr&quot;, rows = 3
-<strong>Output:</strong> &quot;cipher&quot;
-<strong>Explanation:</strong> This is the same example described in the problem description.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/26/exam1.png" style="width: 250px; height: 168px;" />
-<pre>
-<strong>Input:</strong> encodedText = &quot;iveo    eed   l te   olc&quot;, rows = 4
-<strong>Output:</strong> &quot;i love leetcode&quot;
-<strong>Explanation:</strong> The figure above denotes the matrix that was used to encode originalText. 
-The blue arrows show how we can find originalText from encodedText.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/26/eg2.png" style="width: 300px; height: 51px;" />
-<pre>
-<strong>Input:</strong> encodedText = &quot;coding&quot;, rows = 1
-<strong>Output:</strong> &quot;coding&quot;
-<strong>Explanation:</strong> Since there is only 1 row, both originalText and encodedText are the same.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= encodedText.length &lt;= 10<sup>6</sup></code></li>
-	<li><code>encodedText</code> consists of lowercase English letters and <code>&#39; &#39;</code> only.</li>
-	<li><code>encodedText</code> is a valid encoding of some <code>originalText</code> that <strong>does not</strong> have trailing spaces.</li>
-	<li><code>1 &lt;= rows &lt;= 1000</code></li>
-	<li>The testcases are generated such that there is <strong>only one</strong> possible <code>originalText</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can you use rows and encodedText to find the number of columns of the matrix?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Once you have the number of rows and columns, you can create the matrix and place encodedText in it. How should you place it in the matrix?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How should you traverse the matrix to "decode" originalText?
-</details>
diff --git a/problems/decode-ways-ii/README.md b/problems/decode-ways-ii/README.md
deleted file mode 100644
index 7e825db0d..000000000
--- a/problems/decode-ways-ii/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shopping-offers "Shopping Offers")
-　　　　　　　　　　　　　　　　
-[Next >](../solve-the-equation "Solve the Equation")
-
-## [639. Decode Ways II (Hard)](https://leetcode.com/problems/decode-ways-ii "解码方法 II")
-
-<p>A message containing letters from <code>A-Z</code> can be <strong>encoded</strong> into numbers using the following mapping:</p>
-
-<pre>
-&#39;A&#39; -&gt; &quot;1&quot;
-&#39;B&#39; -&gt; &quot;2&quot;
-...
-&#39;Z&#39; -&gt; &quot;26&quot;
-</pre>
-
-<p>To <strong>decode</strong> an encoded message, all the digits must be grouped then mapped back into letters using the reverse of the mapping above (there may be multiple ways). For example, <code>&quot;11106&quot;</code> can be mapped into:</p>
-
-<ul>
-	<li><code>&quot;AAJF&quot;</code> with the grouping <code>(1 1 10 6)</code></li>
-	<li><code>&quot;KJF&quot;</code> with the grouping <code>(11 10 6)</code></li>
-</ul>
-
-<p>Note that the grouping <code>(1 11 06)</code> is invalid because <code>&quot;06&quot;</code> cannot be mapped into <code>&#39;F&#39;</code> since <code>&quot;6&quot;</code> is different from <code>&quot;06&quot;</code>.</p>
-
-<p><strong>In addition</strong> to the mapping above, an encoded message may contain the <code>&#39;*&#39;</code> character, which can represent any digit from <code>&#39;1&#39;</code> to <code>&#39;9&#39;</code> (<code>&#39;0&#39;</code> is excluded). For example, the encoded message <code>&quot;1*&quot;</code> may represent any of the encoded messages <code>&quot;11&quot;</code>, <code>&quot;12&quot;</code>, <code>&quot;13&quot;</code>, <code>&quot;14&quot;</code>, <code>&quot;15&quot;</code>, <code>&quot;16&quot;</code>, <code>&quot;17&quot;</code>, <code>&quot;18&quot;</code>, or <code>&quot;19&quot;</code>. Decoding <code>&quot;1*&quot;</code> is equivalent to decoding <strong>any</strong> of the encoded messages it can represent.</p>
-
-<p>Given a string <code>s</code> consisting of digits and <code>&#39;*&#39;</code> characters, return <em>the <strong>number</strong> of ways to <strong>decode</strong> it</em>.</p>
-
-<p>Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;*&quot;
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> The encoded message can represent any of the encoded messages &quot;1&quot;, &quot;2&quot;, &quot;3&quot;, &quot;4&quot;, &quot;5&quot;, &quot;6&quot;, &quot;7&quot;, &quot;8&quot;, or &quot;9&quot;.
-Each of these can be decoded to the strings &quot;A&quot;, &quot;B&quot;, &quot;C&quot;, &quot;D&quot;, &quot;E&quot;, &quot;F&quot;, &quot;G&quot;, &quot;H&quot;, and &quot;I&quot; respectively.
-Hence, there are a total of 9 ways to decode &quot;*&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1*&quot;
-<strong>Output:</strong> 18
-<strong>Explanation:</strong> The encoded message can represent any of the encoded messages &quot;11&quot;, &quot;12&quot;, &quot;13&quot;, &quot;14&quot;, &quot;15&quot;, &quot;16&quot;, &quot;17&quot;, &quot;18&quot;, or &quot;19&quot;.
-Each of these encoded messages have 2 ways to be decoded (e.g. &quot;11&quot; can be decoded to &quot;AA&quot; or &quot;K&quot;).
-Hence, there are a total of 9 * 2 = 18 ways to decode &quot;1*&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;2*&quot;
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> The encoded message can represent any of the encoded messages &quot;21&quot;, &quot;22&quot;, &quot;23&quot;, &quot;24&quot;, &quot;25&quot;, &quot;26&quot;, &quot;27&quot;, &quot;28&quot;, or &quot;29&quot;.
-&quot;21&quot;, &quot;22&quot;, &quot;23&quot;, &quot;24&quot;, &quot;25&quot;, and &quot;26&quot; have 2 ways of being decoded, but &quot;27&quot;, &quot;28&quot;, and &quot;29&quot; only have 1 way.
-Hence, there are a total of (6 * 2) + (3 * 1) = 12 + 3 = 15 ways to decode &quot;2*&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is a digit or <code>&#39;*&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Decode Ways](../decode-ways) (Medium)
-  1. [Number of Ways to Separate Numbers](../number-of-ways-to-separate-numbers) (Hard)
-  1. [Number of Ways to Divide a Long Corridor](../number-of-ways-to-divide-a-long-corridor) (Hard)
diff --git a/problems/decode-ways-ii/decode_ways_ii.go b/problems/decode-ways-ii/decode_ways_ii.go
deleted file mode 100644
index 543880e17..000000000
--- a/problems/decode-ways-ii/decode_ways_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem639
diff --git a/problems/decode-ways-ii/decode_ways_ii_test.go b/problems/decode-ways-ii/decode_ways_ii_test.go
deleted file mode 100644
index 543880e17..000000000
--- a/problems/decode-ways-ii/decode_ways_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem639
diff --git a/problems/decode-ways/README.md b/problems/decode-ways/README.md
deleted file mode 100644
index 4f55bba1d..000000000
--- a/problems/decode-ways/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subsets-ii "Subsets II")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-linked-list-ii "Reverse Linked List II")
-
-## [91. Decode Ways (Medium)](https://leetcode.com/problems/decode-ways "解码方法")
-
-<p>A message containing letters from <code>A-Z</code> can be <strong>encoded</strong> into numbers using the following mapping:</p>
-
-<pre>
-&#39;A&#39; -&gt; &quot;1&quot;
-&#39;B&#39; -&gt; &quot;2&quot;
-...
-&#39;Z&#39; -&gt; &quot;26&quot;
-</pre>
-
-<p>To <strong>decode</strong> an encoded message, all the digits must be grouped then mapped back into letters using the reverse of the mapping above (there may be multiple ways). For example, <code>&quot;11106&quot;</code> can be mapped into:</p>
-
-<ul>
-	<li><code>&quot;AAJF&quot;</code> with the grouping <code>(1 1 10 6)</code></li>
-	<li><code>&quot;KJF&quot;</code> with the grouping <code>(11 10 6)</code></li>
-</ul>
-
-<p>Note that the grouping <code>(1 11 06)</code> is invalid because <code>&quot;06&quot;</code> cannot be mapped into <code>&#39;F&#39;</code> since <code>&quot;6&quot;</code> is different from <code>&quot;06&quot;</code>.</p>
-
-<p>Given a string <code>s</code> containing only digits, return <em>the <strong>number</strong> of ways to <strong>decode</strong> it</em>.</p>
-
-<p>The answer is guaranteed to fit in a <strong>32-bit</strong> integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;12&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> &quot;12&quot; could be decoded as &quot;AB&quot; (1 2) or &quot;L&quot; (12).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;226&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> &quot;226&quot; could be decoded as &quot;BZ&quot; (2 26), &quot;VF&quot; (22 6), or &quot;BBF&quot; (2 2 6).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no character that is mapped to a number starting with 0.
-The only valid mappings with 0 are &#39;J&#39; -&gt; &quot;10&quot; and &#39;T&#39; -&gt; &quot;20&quot;, neither of which start with 0.
-Hence, there are no valid ways to decode this since all digits need to be mapped.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;06&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> &quot;06&quot; cannot be mapped to &quot;F&quot; because of the leading zero (&quot;6&quot; is different from &quot;06&quot;).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> contains only digits and may contain leading zero(s).</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Decode Ways II](../decode-ways-ii) (Hard)
-  1. [Number of Ways to Separate Numbers](../number-of-ways-to-separate-numbers) (Hard)
diff --git a/problems/decode-ways/decode_ways.go b/problems/decode-ways/decode_ways.go
deleted file mode 100644
index ec5cdea5d..000000000
--- a/problems/decode-ways/decode_ways.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem91
diff --git a/problems/decode-ways/decode_ways_test.go b/problems/decode-ways/decode_ways_test.go
deleted file mode 100644
index ec5cdea5d..000000000
--- a/problems/decode-ways/decode_ways_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem91
diff --git a/problems/decode-xored-array/README.md b/problems/decode-xored-array/README.md
deleted file mode 100644
index a1431e45a..000000000
--- a/problems/decode-xored-array/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-reconstruct-a-tree "Number Of Ways To Reconstruct A Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../swapping-nodes-in-a-linked-list "Swapping Nodes in a Linked List")
-
-## [1720. Decode XORed Array (Easy)](https://leetcode.com/problems/decode-xored-array "解码异或后的数组")
-
-<p>There is a <strong>hidden</strong> integer array <code>arr</code> that consists of <code>n</code> non-negative integers.</p>
-
-<p>It was encoded into another integer array <code>encoded</code> of length <code>n - 1</code>, such that <code>encoded[i] = arr[i] XOR arr[i + 1]</code>. For example, if <code>arr = [1,0,2,1]</code>, then <code>encoded = [1,2,3]</code>.</p>
-
-<p>You are given the <code>encoded</code> array. You are also given an integer <code>first</code>, that is the first element of <code>arr</code>, i.e. <code>arr[0]</code>.</p>
-
-<p>Return <em>the original array</em> <code>arr</code>. It can be proved that the answer exists and is unique.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> encoded = [1,2,3], first = 1
-<strong>Output:</strong> [1,0,2,1]
-<strong>Explanation:</strong> If arr = [1,0,2,1], then first = 1 and encoded = [1 XOR 0, 0 XOR 2, 2 XOR 1] = [1,2,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> encoded = [6,2,7,3], first = 4
-<strong>Output:</strong> [4,2,0,7,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>encoded.length == n - 1</code></li>
-	<li><code>0 &lt;= encoded[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= first &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since that encoded[i] = arr[i] XOR arr[i+1], then arr[i+1] = encoded[i] XOR arr[i].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Iterate on i from beginning to end, and set arr[i+1] = encoded[i] XOR arr[i].
-</details>
diff --git a/problems/decode-xored-permutation/README.md b/problems/decode-xored-permutation/README.md
deleted file mode 100644
index f1782835e..000000000
--- a/problems/decode-xored-permutation/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-people-to-teach "Minimum Number of People to Teach")
-　　　　　　　　　　　　　　　　
-[Next >](../count-ways-to-make-array-with-product "Count Ways to Make Array With Product")
-
-## [1734. Decode XORed Permutation (Medium)](https://leetcode.com/problems/decode-xored-permutation "解码异或后的排列")
-
-<p>There is an integer array <code>perm</code> that is a permutation of the first <code>n</code> positive integers, where <code>n</code> is always <strong>odd</strong>.</p>
-
-<p>It was encoded into another integer array <code>encoded</code> of length <code>n - 1</code>, such that <code>encoded[i] = perm[i] XOR perm[i + 1]</code>. For example, if <code>perm = [1,3,2]</code>, then <code>encoded = [2,1]</code>.</p>
-
-<p>Given the <code>encoded</code> array, return <em>the original array</em> <code>perm</code>. It is guaranteed that the answer exists and is unique.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> encoded = [3,1]
-<strong>Output:</strong> [1,2,3]
-<strong>Explanation:</strong> If perm = [1,2,3], then encoded = [1 XOR 2,2 XOR 3] = [3,1]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> encoded = [6,5,4,6]
-<strong>Output:</strong> [2,4,1,5,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= n &lt;&nbsp;10<sup>5</sup></code></li>
-	<li><code>n</code>&nbsp;is odd.</li>
-	<li><code>encoded.length == n - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Compute the XOR of the numbers between 1 and n, and think about how it can be used. Let it be x.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think why n is odd.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-perm[0] = x XOR encoded[1] XOR encoded[3] XOR encoded[5] ...
-</details>
-
-<details>
-<summary>Hint 4</summary>
-perm[i] = perm[i-1] XOR encoded[i-1]
-</details>
diff --git a/problems/decoded-string-at-index/README.md b/problems/decoded-string-at-index/README.md
deleted file mode 100644
index db82b21f2..000000000
--- a/problems/decoded-string-at-index/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../profitable-schemes "Profitable Schemes")
-　　　　　　　　　　　　　　　　
-[Next >](../boats-to-save-people "Boats to Save People")
-
-## [880. Decoded String at Index (Medium)](https://leetcode.com/problems/decoded-string-at-index "索引处的解码字符串")
-
-<p>You are given an encoded string <code>s</code>. To decode the string to a tape, the encoded string is read one character at a time and the following steps are taken:</p>
-
-<ul>
-	<li>If the character read is a letter, that letter is written onto the tape.</li>
-	<li>If the character read is a digit <code>d</code>, the entire current tape is repeatedly written <code>d - 1</code> more times in total.</li>
-</ul>
-
-<p>Given an integer <code>k</code>, return <em>the </em><code>k<sup>th</sup></code><em> letter (<strong>1-indexed)</strong> in the decoded string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leet2code3&quot;, k = 10
-<strong>Output:</strong> &quot;o&quot;
-<strong>Explanation:</strong> The decoded string is &quot;leetleetcodeleetleetcodeleetleetcode&quot;.
-The 10<sup>th</sup> letter in the string is &quot;o&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ha22&quot;, k = 5
-<strong>Output:</strong> &quot;h&quot;
-<strong>Explanation:</strong> The decoded string is &quot;hahahaha&quot;.
-The 5<sup>th</sup> letter is &quot;h&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a2345678999999999999999&quot;, k = 1
-<strong>Output:</strong> &quot;a&quot;
-<strong>Explanation:</strong> The decoded string is &quot;a&quot; repeated 8301530446056247680 times.
-The 1<sup>st</sup> letter is &quot;a&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> consists of lowercase English letters and digits <code>2</code> through <code>9</code>.</li>
-	<li><code>s</code> starts with a letter.</li>
-	<li><code>1 &lt;= k &lt;= 10<sup>9</sup></code></li>
-	<li>It is guaranteed that <code>k</code> is less than or equal to the length of the decoded string.</li>
-	<li>The decoded string is guaranteed to have less than <code>2<sup>63</sup></code> letters.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/decoded-string-at-index/decoded_string_at_index.go b/problems/decoded-string-at-index/decoded_string_at_index.go
deleted file mode 100644
index 38e4dffda..000000000
--- a/problems/decoded-string-at-index/decoded_string_at_index.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem880
diff --git a/problems/decoded-string-at-index/decoded_string_at_index_test.go b/problems/decoded-string-at-index/decoded_string_at_index_test.go
deleted file mode 100644
index 38e4dffda..000000000
--- a/problems/decoded-string-at-index/decoded_string_at_index_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem880
diff --git a/problems/decompress-run-length-encoded-list/README.md b/problems/decompress-run-length-encoded-list/README.md
deleted file mode 100644
index cda578f8a..000000000
--- a/problems/decompress-run-length-encoded-list/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-insertion-steps-to-make-a-string-palindrome "Minimum Insertion Steps to Make a String Palindrome")
-　　　　　　　　　　　　　　　　
-[Next >](../matrix-block-sum "Matrix Block Sum")
-
-## [1313. Decompress Run-Length Encoded List (Easy)](https://leetcode.com/problems/decompress-run-length-encoded-list "解压缩编码列表")
-
-<p>We are given a list <code>nums</code> of integers representing a list compressed with run-length encoding.</p>
-
-<p>Consider each adjacent pair&nbsp;of elements <code>[freq, val] = [nums[2*i], nums[2*i+1]]</code>&nbsp;(with <code>i &gt;= 0</code>).&nbsp; For each such pair, there are <code>freq</code> elements with value <code>val</code> concatenated in a sublist. Concatenate all the sublists from left to right to generate the decompressed list.</p>
-
-<p>Return the decompressed list.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> [2,4,4,4]
-<strong>Explanation:</strong> The first pair [1,2] means we have freq = 1 and val = 2 so we generate the array [2].
-The second pair [3,4] means we have freq = 3 and val = 4 so we generate [4,4,4].
-At the end the concatenation [2] + [4,4,4] is [2,4,4,4].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,2,3]
-<strong>Output:</strong> [1,3,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>nums.length % 2 == 0</code></li>
-	<li><code><font face="monospace">1 &lt;= nums[i] &lt;= 100</font></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [String Compression](../string-compression) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Decompress the given array by repeating nums[2*i+1] a number of times equal to nums[2*i].
-</details>
diff --git a/problems/decrease-elements-to-make-array-zigzag/README.md b/problems/decrease-elements-to-make-array-zigzag/README.md
deleted file mode 100644
index 1abcb21e0..000000000
--- a/problems/decrease-elements-to-make-array-zigzag/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-common-subsequence "Longest Common Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-coloring-game "Binary Tree Coloring Game")
-
-## [1144. Decrease Elements To Make Array Zigzag (Medium)](https://leetcode.com/problems/decrease-elements-to-make-array-zigzag "递减元素使数组呈锯齿状")
-
-<p>Given an array <code>nums</code> of integers, a <em>move</em>&nbsp;consists of choosing any element and <strong>decreasing it by 1</strong>.</p>
-
-<p>An array <code>A</code> is a&nbsp;<em>zigzag array</em>&nbsp;if either:</p>
-
-<ul>
-	<li>Every even-indexed element is greater than adjacent elements, ie.&nbsp;<code>A[0] &gt; A[1] &lt; A[2] &gt; A[3] &lt; A[4] &gt; ...</code></li>
-	<li>OR, every odd-indexed element is greater than adjacent elements, ie.&nbsp;<code>A[0] &lt; A[1] &gt; A[2] &lt; A[3] &gt; A[4] &lt; ...</code></li>
-</ul>
-
-<p>Return the minimum number of moves to transform the given array <code>nums</code> into a zigzag array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We can decrease 2 to 0 or 3 to 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,6,1,6,2]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do each case (even indexed is greater, odd indexed is greater) separately. In say the even case, you should decrease each even-indexed element until it is lower than its immediate neighbors.
-</details>
diff --git a/problems/decrypt-string-from-alphabet-to-integer-mapping/README.md b/problems/decrypt-string-from-alphabet-to-integer-mapping/README.md
deleted file mode 100644
index 51121f55c..000000000
--- a/problems/decrypt-string-from-alphabet-to-integer-mapping/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../running-total-for-different-genders "Running Total for Different Genders")
-　　　　　　　　　　　　　　　　
-[Next >](../xor-queries-of-a-subarray "XOR Queries of a Subarray")
-
-## [1309. Decrypt String from Alphabet to Integer Mapping (Easy)](https://leetcode.com/problems/decrypt-string-from-alphabet-to-integer-mapping "解码字母到整数映射")
-
-<p>You are given a string <code>s</code> formed by digits and <code>&#39;#&#39;</code>. We want to map <code>s</code> to English lowercase characters as follows:</p>
-
-<ul>
-	<li>Characters (<code>&#39;a&#39;</code> to <code>&#39;i&#39;)</code> are represented by (<code>&#39;1&#39;</code> to <code>&#39;9&#39;</code>) respectively.</li>
-	<li>Characters (<code>&#39;j&#39;</code> to <code>&#39;z&#39;)</code> are represented by (<code>&#39;10#&#39;</code> to <code>&#39;26#&#39;</code>) respectively.</li>
-</ul>
-
-<p>Return <em>the string formed after mapping</em>.</p>
-
-<p>The test cases are generated so that a unique mapping will always exist.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;10#11#12&quot;
-<strong>Output:</strong> &quot;jkab&quot;
-<strong>Explanation:</strong> &quot;j&quot; -&gt; &quot;10#&quot; , &quot;k&quot; -&gt; &quot;11#&quot; , &quot;a&quot; -&gt; &quot;1&quot; , &quot;b&quot; -&gt; &quot;2&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1326#&quot;
-<strong>Output:</strong> &quot;acz&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> consists of digits and the <code>&#39;#&#39;</code> letter.</li>
-	<li><code>s</code> will be a valid string such that mapping is always possible.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Scan from right to left, in each step of the scanning check whether there is a trailing "#" 2 indexes away.
-</details>
diff --git a/problems/decrypt-string-from-alphabet-to-integer-mapping/decrypt_string_from_alphabet_to_integer_mapping.go b/problems/decrypt-string-from-alphabet-to-integer-mapping/decrypt_string_from_alphabet_to_integer_mapping.go
deleted file mode 100644
index e6bdc5079..000000000
--- a/problems/decrypt-string-from-alphabet-to-integer-mapping/decrypt_string_from_alphabet_to_integer_mapping.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem1309
-
-func freqAlphabets(s string) string {
-	l := len(s)
-	ans, head := make([]byte, l), l-1
-	for i := l - 1; i >= 0; i-- {
-		if s[i] == '#' {
-			ans[head] = 'a' + (s[i-1] - '1') + (s[i-2]-'0')*10
-			i -= 2
-		} else {
-			ans[head] = 'a' + (s[i] - '1')
-		}
-		head--
-	}
-	return string(ans[head+1:])
-}
diff --git a/problems/decrypt-string-from-alphabet-to-integer-mapping/decrypt_string_from_alphabet_to_integer_mapping_test.go b/problems/decrypt-string-from-alphabet-to-integer-mapping/decrypt_string_from_alphabet_to_integer_mapping_test.go
deleted file mode 100644
index 1fadf7105..000000000
--- a/problems/decrypt-string-from-alphabet-to-integer-mapping/decrypt_string_from_alphabet_to_integer_mapping_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem1309
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestFreqAlphabets(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "10#11#12",
-			want: "jkab",
-		},
-		{
-			in:   "1326#",
-			want: "acz",
-		},
-		{
-			in:   "12345678910#11#12#13#14#15#16#17#18#19#20#21#22#23#24#25#26#",
-			want: "abcdefghijklmnopqrstuvwxyz",
-		},
-	}
-	for _, tt := range tests {
-		got := freqAlphabets(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/deepest-leaves-sum/README.md b/problems/deepest-leaves-sum/README.md
deleted file mode 100644
index 82c34bc7f..000000000
--- a/problems/deepest-leaves-sum/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-paths-with-max-score "Number of Paths with Max Score")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-team-size "Find the Team Size")
-
-## [1302. Deepest Leaves Sum (Medium)](https://leetcode.com/problems/deepest-leaves-sum "层数最深叶子节点的和")
-
-Given the <code>root</code> of a binary tree, return <em>the sum of values of its deepest leaves</em>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/07/31/1483_ex1.png" style="width: 273px; height: 265px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,null,6,7,null,null,null,null,8]
-<strong>Output:</strong> 15
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5]
-<strong>Output:</strong> 19
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Traverse the tree to find the max depth.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Traverse the tree again to compute the sum required.
-</details>
diff --git a/problems/defanging-an-ip-address/README.md b/problems/defanging-an-ip-address/README.md
deleted file mode 100644
index 1a89b5589..000000000
--- a/problems/defanging-an-ip-address/README.md
+++ /dev/null
@@ -1,34 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../new-users-daily-count "New Users Daily Count")
-　　　　　　　　　　　　　　　　
-[Next >](../corporate-flight-bookings "Corporate Flight Bookings")
-
-## [1108. Defanging an IP Address (Easy)](https://leetcode.com/problems/defanging-an-ip-address "IP 地址无效化")
-
-<p>Given a valid (IPv4) IP <code>address</code>, return a defanged version of that IP address.</p>
-
-<p>A <em>defanged&nbsp;IP address</em>&nbsp;replaces every period <code>&quot;.&quot;</code> with <code>&quot;[.]&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> address = "1.1.1.1"
-<strong>Output:</strong> "1[.]1[.]1[.]1"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> address = "255.100.50.0"
-<strong>Output:</strong> "255[.]100[.]50[.]0"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The given <code>address</code> is a valid IPv4 address.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/defanging-an-ip-address/defanging_an_ip_address.go b/problems/defanging-an-ip-address/defanging_an_ip_address.go
deleted file mode 100644
index f7276fb56..000000000
--- a/problems/defanging-an-ip-address/defanging_an_ip_address.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem1108
-
-import "strings"
-
-func defangIPaddr(address string) string {
-	return strings.ReplaceAll(address, ".", "[.]")
-}
diff --git a/problems/defanging-an-ip-address/defanging_an_ip_address_test.go b/problems/defanging-an-ip-address/defanging_an_ip_address_test.go
deleted file mode 100644
index b3401e99f..000000000
--- a/problems/defanging-an-ip-address/defanging_an_ip_address_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem1108
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestDefangIPaddr(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "1.1.1.1",
-			want: "1[.]1[.]1[.]1",
-		},
-		{
-			in:   "255.100.50.0",
-			want: "255[.]100[.]50[.]0",
-		},
-	}
-	for _, tt := range tests {
-		got := defangIPaddr(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/defuse-the-bomb/README.md b/problems/defuse-the-bomb/README.md
deleted file mode 100644
index efc8b1b80..000000000
--- a/problems/defuse-the-bomb/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../hopper-company-queries-iii "Hopper Company Queries III")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-deletions-to-make-string-balanced "Minimum Deletions to Make String Balanced")
-
-## [1652. Defuse the Bomb (Easy)](https://leetcode.com/problems/defuse-the-bomb "拆炸弹")
-
-<p>You have a bomb to defuse, and your time is running out! Your informer will provide you with a <strong>circular</strong> array <code>code</code>&nbsp;of length of <code>n</code>&nbsp;and a key <code>k</code>.</p>
-
-<p>To decrypt the code, you must replace every number. All the numbers are replaced <strong>simultaneously</strong>.</p>
-
-<ul>
-	<li>If <code>k &gt; 0</code>, replace the <code>i<sup>th</sup></code> number with the sum of the <strong>next</strong> <code>k</code> numbers.</li>
-	<li>If <code>k &lt; 0</code>, replace the <code>i<sup>th</sup></code> number with the sum of the <strong>previous</strong> <code>k</code> numbers.</li>
-	<li>If <code>k == 0</code>, replace the <code>i<sup>th</sup></code> number with <code>0</code>.</li>
-</ul>
-
-<p>As <code>code</code> is circular, the next element of <code>code[n-1]</code> is <code>code[0]</code>, and the previous element of <code>code[0]</code> is <code>code[n-1]</code>.</p>
-
-<p>Given the <strong>circular</strong> array <code>code</code> and an integer key <code>k</code>, return <em>the decrypted code to defuse the bomb</em>!</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> code = [5,7,1,4], k = 3
-<strong>Output:</strong> [12,10,16,13]
-<strong>Explanation:</strong> Each number is replaced by the sum of the next 3 numbers. The decrypted code is [7+1+4, 1+4+5, 4+5+7, 5+7+1]. Notice that the numbers wrap around.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> code = [1,2,3,4], k = 0
-<strong>Output:</strong> [0,0,0,0]
-<strong>Explanation:</strong> When k is zero, the numbers are replaced by 0. 
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> code = [2,4,9,3], k = -2
-<strong>Output:</strong> [12,5,6,13]
-<strong>Explanation:</strong> The decrypted code is [3+9, 2+3, 4+2, 9+4]. Notice that the numbers wrap around again. If k is negative, the sum is of the <strong>previous</strong> numbers.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == code.length</code></li>
-	<li><code>1 &lt;= n&nbsp;&lt;= 100</code></li>
-	<li><code>1 &lt;= code[i] &lt;= 100</code></li>
-	<li><code>-(n - 1) &lt;= k &lt;= n - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-As the array is circular, use modulo to find the correct index.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The constraints are low enough for a brute-force solution.
-</details>
diff --git a/problems/degree-of-an-array/README.md b/problems/degree-of-an-array/README.md
deleted file mode 100644
index 46abd362f..000000000
--- a/problems/degree-of-an-array/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-binary-substrings "Count Binary Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../partition-to-k-equal-sum-subsets "Partition to K Equal Sum Subsets")
-
-## [697. Degree of an Array (Easy)](https://leetcode.com/problems/degree-of-an-array "数组的度")
-
-<p>Given a non-empty array of non-negative integers <code>nums</code>, the <b>degree</b> of this array is defined as the maximum frequency of any one of its elements.</p>
-
-<p>Your task is to find the smallest possible length of a (contiguous) subarray of <code>nums</code>, that has the same degree as <code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,2,3,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-The input array has a degree of 2 because both elements 1 and 2 appear twice.
-Of the subarrays that have the same degree:
-[1, 2, 2, 3, 1], [1, 2, 2, 3], [2, 2, 3, 1], [1, 2, 2], [2, 2, 3], [2, 2]
-The shortest length is 2. So return 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,2,3,1,4,2]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> 
-The degree is 3 because the element 2 is repeated 3 times.
-So [2,2,3,1,4,2] is the shortest subarray, therefore returning 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>nums.length</code> will be between 1 and 50,000.</li>
-	<li><code>nums[i]</code> will be an integer between 0 and 49,999.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [Maximum Subarray](../maximum-subarray) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Say 5 is the only element that occurs the most number of times - for example, nums = [1, 5, 2, 3, 5, 4, 5, 6].  What is the answer?
-</details>
diff --git a/problems/degree-of-an-array/degree_of_an_array.go b/problems/degree-of-an-array/degree_of_an_array.go
deleted file mode 100644
index 1901e8292..000000000
--- a/problems/degree-of-an-array/degree_of_an_array.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem697
-
-func findShortestSubArray(nums []int) int {
-	m, ans := make(map[int]int), 0
-	first, max := make(map[int]int), 0
-	for i, v := range nums {
-		m[v]++
-		if first[v] == 0 {
-			first[v] = i + 1
-		}
-		if m[v] >= max {
-			t := i - first[v] + 2
-			if m[v] > max || (m[v] == max && t < ans) {
-				ans = t
-			}
-			max = m[v]
-		}
-	}
-	return ans
-}
diff --git a/problems/degree-of-an-array/degree_of_an_array_test.go b/problems/degree-of-an-array/degree_of_an_array_test.go
deleted file mode 100644
index e9a9e7d4e..000000000
--- a/problems/degree-of-an-array/degree_of_an_array_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem697
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestFindShortestSubArray(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 2, 3, 1},
-			want: 2,
-		},
-		{
-			in:   []int{1, 2, 2, 3, 1, 4, 2},
-			want: 6,
-		},
-		{
-			in:   []int{1},
-			want: 1,
-		},
-		{
-			in:   []int{2, 1, 1, 2, 1, 3, 3, 3, 1, 3, 1, 3, 2},
-			want: 7,
-		},
-		{
-			in:   []int{1, 2, 2, 3, 1},
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := findShortestSubArray(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/delete-and-earn/README.md b/problems/delete-and-earn/README.md
deleted file mode 100644
index a76cd1977..000000000
--- a/problems/delete-and-earn/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../daily-temperatures "Daily Temperatures")
-　　　　　　　　　　　　　　　　
-[Next >](../cherry-pickup "Cherry Pickup")
-
-## [740. Delete and Earn (Medium)](https://leetcode.com/problems/delete-and-earn "删除并获得点数")
-
-<p>You are given an integer array <code>nums</code>. You want to maximize the number of points you get by performing the following operation any number of times:</p>
-
-<ul>
-	<li>Pick any <code>nums[i]</code> and delete it to earn <code>nums[i]</code> points. Afterwards, you must delete <b>every</b> element equal to <code>nums[i] - 1</code> and <strong>every</strong> element equal to <code>nums[i] + 1</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>maximum number of points</strong> you can earn by applying the above operation some number of times</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,4,2]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> You can perform the following operations:
-- Delete 4 to earn 4 points. Consequently, 3 is also deleted. nums = [2].
-- Delete 2 to earn 2 points. nums = [].
-You earn a total of 6 points.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,3,3,3,4]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> You can perform the following operations:
-- Delete a 3 to earn 3 points. All 2&#39;s and 4&#39;s are also deleted. nums = [3,3].
-- Delete a 3 again to earn 3 points. nums = [3].
-- Delete a 3 once more to earn 3 points. nums = [].
-You earn a total of 9 points.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [House Robber](../house-robber) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you take a number, you might as well take them all.  Keep track of what the value is of the subset of the input with maximum M when you either take or don't take M.
-</details>
diff --git a/problems/delete-and-earn/delete_and_earn.go b/problems/delete-and-earn/delete_and_earn.go
deleted file mode 100644
index 8de02ee07..000000000
--- a/problems/delete-and-earn/delete_and_earn.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem740
diff --git a/problems/delete-and-earn/delete_and_earn_test.go b/problems/delete-and-earn/delete_and_earn_test.go
deleted file mode 100644
index 8de02ee07..000000000
--- a/problems/delete-and-earn/delete_and_earn_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem740
diff --git a/problems/delete-characters-to-make-fancy-string/README.md b/problems/delete-characters-to-make-fancy-string/README.md
deleted file mode 100644
index 786cb11c1..000000000
--- a/problems/delete-characters-to-make-fancy-string/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-time-for-k-virus-variants-to-spread "Minimum Time For K Virus Variants to Spread")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-move-is-legal "Check if Move is Legal")
-
-## [1957. Delete Characters to Make Fancy String (Easy)](https://leetcode.com/problems/delete-characters-to-make-fancy-string "删除字符使字符串变好")
-
-<p>A <strong>fancy string</strong> is a string where no <strong>three</strong> <strong>consecutive</strong> characters are equal.</p>
-
-<p>Given a string <code>s</code>, delete the <strong>minimum</strong> possible number of characters from <code>s</code> to make it <strong>fancy</strong>.</p>
-
-<p>Return <em>the final string after the deletion</em>. It can be shown that the answer will always be <strong>unique</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;le<u>e</u>etcode&quot;
-<strong>Output:</strong> &quot;leetcode&quot;
-<strong>Explanation:</strong>
-Remove an &#39;e&#39; from the first group of &#39;e&#39;s to create &quot;leetcode&quot;.
-No three consecutive characters are equal, so return &quot;leetcode&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;<u>a</u>aab<u>aa</u>aa&quot;
-<strong>Output:</strong> &quot;aabaa&quot;
-<strong>Explanation:</strong>
-Remove an &#39;a&#39; from the first group of &#39;a&#39;s to create &quot;aabaaaa&quot;.
-Remove two &#39;a&#39;s from the second group of &#39;a&#39;s to create &quot;aabaa&quot;.
-No three consecutive characters are equal, so return &quot;aabaa&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aab&quot;
-<strong>Output:</strong> &quot;aab&quot;
-<strong>Explanation:</strong> No three consecutive characters are equal, so return &quot;aab&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What's the optimal way to delete characters if three or more consecutive characters are equal?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If three or more consecutive characters are equal, keep two of them and delete the rest.
-</details>
diff --git a/problems/delete-columns-to-make-sorted-ii/README.md b/problems/delete-columns-to-make-sorted-ii/README.md
deleted file mode 100644
index 6ead9d1b4..000000000
--- a/problems/delete-columns-to-make-sorted-ii/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../array-of-doubled-pairs "Array of Doubled Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../tallest-billboard "Tallest Billboard")
-
-## [955. Delete Columns to Make Sorted II (Medium)](https://leetcode.com/problems/delete-columns-to-make-sorted-ii "删列造序 II")
-
-<p>You are given an array of <code>n</code> strings <code>strs</code>, all of the same length.</p>
-
-<p>We may choose any deletion indices, and we delete all the characters in those indices for each string.</p>
-
-<p>For example, if we have <code>strs = [&quot;abcdef&quot;,&quot;uvwxyz&quot;]</code> and deletion indices <code>{0, 2, 3}</code>, then the final array after deletions is <code>[&quot;bef&quot;, &quot;vyz&quot;]</code>.</p>
-
-<p>Suppose we chose a set of deletion indices <code>answer</code> such that after deletions, the final array has its elements in <strong>lexicographic</strong> order (i.e., <code>strs[0] &lt;= strs[1] &lt;= strs[2] &lt;= ... &lt;= strs[n - 1]</code>). Return <em>the minimum possible value of</em> <code>answer.length</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;ca&quot;,&quot;bb&quot;,&quot;ac&quot;]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 
-After deleting the first column, strs = [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;].
-Now strs is in lexicographic order (ie. strs[0] &lt;= strs[1] &lt;= strs[2]).
-We require at least 1 deletion since initially strs was not in lexicographic order, so the answer is 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;xc&quot;,&quot;yb&quot;,&quot;za&quot;]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> 
-strs is already in lexicographic order, so we do not need to delete anything.
-Note that the rows of strs are not necessarily in lexicographic order:
-i.e., it is NOT necessarily true that (strs[0][0] &lt;= strs[0][1] &lt;= ...)
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;zyx&quot;,&quot;wvu&quot;,&quot;tsr&quot;]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We have to delete every column.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == strs.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= strs[i].length &lt;= 100</code></li>
-	<li><code>strs[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/delete-columns-to-make-sorted-ii/delete_columns_to_make_sorted_ii.go b/problems/delete-columns-to-make-sorted-ii/delete_columns_to_make_sorted_ii.go
deleted file mode 100644
index 07cc0eeb1..000000000
--- a/problems/delete-columns-to-make-sorted-ii/delete_columns_to_make_sorted_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem955
diff --git a/problems/delete-columns-to-make-sorted-ii/delete_columns_to_make_sorted_ii_test.go b/problems/delete-columns-to-make-sorted-ii/delete_columns_to_make_sorted_ii_test.go
deleted file mode 100644
index 07cc0eeb1..000000000
--- a/problems/delete-columns-to-make-sorted-ii/delete_columns_to_make_sorted_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem955
diff --git a/problems/delete-columns-to-make-sorted-iii/README.md b/problems/delete-columns-to-make-sorted-iii/README.md
deleted file mode 100644
index 59d134d37..000000000
--- a/problems/delete-columns-to-make-sorted-iii/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../regions-cut-by-slashes "Regions Cut By Slashes")
-　　　　　　　　　　　　　　　　
-[Next >](../n-repeated-element-in-size-2n-array "N-Repeated Element in Size 2N Array")
-
-## [960. Delete Columns to Make Sorted III (Hard)](https://leetcode.com/problems/delete-columns-to-make-sorted-iii "删列造序 III")
-
-<p>You are given an array of <code>n</code> strings <code>strs</code>, all of the same length.</p>
-
-<p>We may choose any deletion indices, and we delete all the characters in those indices for each string.</p>
-
-<p>For example, if we have <code>strs = [&quot;abcdef&quot;,&quot;uvwxyz&quot;]</code> and deletion indices <code>{0, 2, 3}</code>, then the final array after deletions is <code>[&quot;bef&quot;, &quot;vyz&quot;]</code>.</p>
-
-<p>Suppose we chose a set of deletion indices <code>answer</code> such that after deletions, the final array has <strong>every string (row) in lexicographic</strong> order. (i.e., <code>(strs[0][0] &lt;= strs[0][1] &lt;= ... &lt;= strs[0][strs[0].length - 1])</code>, and <code>(strs[1][0] &lt;= strs[1][1] &lt;= ... &lt;= strs[1][strs[1].length - 1])</code>, and so on). Return <em>the minimum possible value of</em> <code>answer.length</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;babca&quot;,&quot;bbazb&quot;]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> After deleting columns 0, 1, and 4, the final array is strs = [&quot;bc&quot;, &quot;az&quot;].
-Both these rows are individually in lexicographic order (ie. strs[0][0] &lt;= strs[0][1] and strs[1][0] &lt;= strs[1][1]).
-Note that strs[0] &gt; strs[1] - the array strs is not necessarily in lexicographic order.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;edcba&quot;]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> If we delete less than 4 columns, the only row will not be lexicographically sorted.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;ghi&quot;,&quot;def&quot;,&quot;abc&quot;]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> All rows are already lexicographically sorted.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == strs.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= strs[i].length &lt;= 100</code></li>
-	<li><code>strs[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-<ul>
-	<li>&nbsp;</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/delete-columns-to-make-sorted-iii/delete_columns_to_make_sorted_iii.go b/problems/delete-columns-to-make-sorted-iii/delete_columns_to_make_sorted_iii.go
deleted file mode 100644
index f2ba710be..000000000
--- a/problems/delete-columns-to-make-sorted-iii/delete_columns_to_make_sorted_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem960
diff --git a/problems/delete-columns-to-make-sorted-iii/delete_columns_to_make_sorted_iii_test.go b/problems/delete-columns-to-make-sorted-iii/delete_columns_to_make_sorted_iii_test.go
deleted file mode 100644
index f2ba710be..000000000
--- a/problems/delete-columns-to-make-sorted-iii/delete_columns_to_make_sorted_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem960
diff --git a/problems/delete-columns-to-make-sorted/README.md b/problems/delete-columns-to-make-sorted/README.md
deleted file mode 100644
index 4586eece7..000000000
--- a/problems/delete-columns-to-make-sorted/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-shortest-superstring "Find the Shortest Superstring")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-increment-to-make-array-unique "Minimum Increment to Make Array Unique")
-
-## [944. Delete Columns to Make Sorted (Easy)](https://leetcode.com/problems/delete-columns-to-make-sorted "删列造序")
-
-<p>You are given an array of <code>n</code> strings <code>strs</code>, all of the same length.</p>
-
-<p>The strings can be arranged such that there is one on each line, making a grid. For example, <code>strs = [&quot;abc&quot;, &quot;bce&quot;, &quot;cae&quot;]</code> can be arranged as:</p>
-
-<pre>
-abc
-bce
-cae
-</pre>
-
-<p>You want to <strong>delete</strong> the columns that are <strong>not sorted lexicographically</strong>. In the above example (0-indexed), columns 0 (<code>&#39;a&#39;</code>, <code>&#39;b&#39;</code>, <code>&#39;c&#39;</code>) and 2 (<code>&#39;c&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;e&#39;</code>) are sorted while column 1 (<code>&#39;b&#39;</code>, <code>&#39;c&#39;</code>, <code>&#39;a&#39;</code>) is not, so you would delete column 1.</p>
-
-<p>Return <em>the number of columns that you will delete</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;cba&quot;,&quot;daf&quot;,&quot;ghi&quot;]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The grid looks as follows:
-  cba
-  daf
-  ghi
-Columns 0 and 2 are sorted, but column 1 is not, so you only need to delete 1 column.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;a&quot;,&quot;b&quot;]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The grid looks as follows:
-  a
-  b
-Column 0 is the only column and is sorted, so you will not delete any columns.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;zyx&quot;,&quot;wvu&quot;,&quot;tsr&quot;]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The grid looks as follows:
-  zyx
-  wvu
-  tsr
-All 3 columns are not sorted, so you will delete all 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == strs.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= strs[i].length &lt;= 1000</code></li>
-	<li><code>strs[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/delete-columns-to-make-sorted/delete_columns_to_make_sorted.go b/problems/delete-columns-to-make-sorted/delete_columns_to_make_sorted.go
deleted file mode 100644
index dca8cd1b4..000000000
--- a/problems/delete-columns-to-make-sorted/delete_columns_to_make_sorted.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem944
-
-func minDeletionSize(A []string) int {
-	ans := 0
-	for i := 0; i < len(A[0]); i++ {
-		for j, str := range A[1:] {
-			if str[i] < A[j][i] {
-				ans++
-				break
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/delete-columns-to-make-sorted/delete_columns_to_make_sorted_test.go b/problems/delete-columns-to-make-sorted/delete_columns_to_make_sorted_test.go
deleted file mode 100644
index a7c21ed02..000000000
--- a/problems/delete-columns-to-make-sorted/delete_columns_to_make_sorted_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem944
-
-import "testing"
-
-type testType struct {
-	in   []string
-	want int
-}
-
-func TestMinDeletionSize(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []string{"cba", "daf", "ghi"},
-			want: 1,
-		},
-		{
-			in:   []string{"a", "b"},
-			want: 0,
-		},
-		{
-			in:   []string{"zyx", "wvu", "tsr"},
-			want: 3,
-		},
-	}
-	for _, tt := range tests {
-		got := minDeletionSize(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/delete-duplicate-emails/README.md b/problems/delete-duplicate-emails/README.md
deleted file mode 100644
index f2ba686fb..000000000
--- a/problems/delete-duplicate-emails/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tenth-line "Tenth Line")
-　　　　　　　　　　　　　　　　
-[Next >](../rising-temperature "Rising Temperature")
-
-## [196. Delete Duplicate Emails (Easy)](https://leetcode.com/problems/delete-duplicate-emails "删除重复的电子邮箱")
-
-<p>Table: <code>Person</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| id          | int     |
-| email       | varchar |
-+-------------+---------+
-id is the primary key column for this table.
-Each row of this table contains an email. The emails will not contain uppercase letters.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to <strong>delete</strong> all the duplicate emails, keeping only one unique email with the smallest <code>id</code>. Note that you are supposed to write a<code> DELETE</code> statement and not a <code>SELECT</code> one.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Person table:
-+----+------------------+
-| id | email            |
-+----+------------------+
-| 1  | john@example.com |
-| 2  | bob@example.com  |
-| 3  | john@example.com |
-+----+------------------+
-<strong>Output:</strong> 
-+----+------------------+
-| id | email            |
-+----+------------------+
-| 1  | john@example.com |
-| 2  | bob@example.com  |
-+----+------------------+
-<strong>Explanation:</strong> john@example.com is repeated two times. We keep the row with the smallest Id = 1.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/delete-duplicate-emails/delete_duplicate_emails.sql b/problems/delete-duplicate-emails/delete_duplicate_emails.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/delete-duplicate-emails/delete_duplicate_emails.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/delete-duplicate-emails/mysql_schemas.sql b/problems/delete-duplicate-emails/mysql_schemas.sql
deleted file mode 100644
index 6ee53bdfa..000000000
--- a/problems/delete-duplicate-emails/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create table If Not Exists Person (Id int, Email varchar(255));
-Truncate table Person;
-insert into Person (id, email) values ('1', 'john@example.com');
-insert into Person (id, email) values ('2', 'bob@example.com');
-insert into Person (id, email) values ('3', 'john@example.com');
diff --git a/problems/delete-duplicate-folders-in-system/README.md b/problems/delete-duplicate-folders-in-system/README.md
deleted file mode 100644
index 7e5d89477..000000000
--- a/problems/delete-duplicate-folders-in-system/README.md
+++ /dev/null
@@ -1,101 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-compatibility-score-sum "Maximum Compatibility Score Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../strong-friendship "Strong Friendship")
-
-## [1948. Delete Duplicate Folders in System (Hard)](https://leetcode.com/problems/delete-duplicate-folders-in-system "删除系统中的重复文件夹")
-
-<p>Due to a bug, there are many duplicate folders in a file system. You are given a 2D array <code>paths</code>, where <code>paths[i]</code> is an array representing an absolute path to the <code>i<sup>th</sup></code> folder in the file system.</p>
-
-<ul>
-	<li>For example, <code>[&quot;one&quot;, &quot;two&quot;, &quot;three&quot;]</code> represents the path <code>&quot;/one/two/three&quot;</code>.</li>
-</ul>
-
-<p>Two folders (not necessarily on the same level) are <strong>identical</strong> if they contain the <strong>same non-empty</strong> set of identical subfolders and underlying subfolder structure. The folders <strong>do not</strong> need to be at the root level to be identical. If two or more folders are <strong>identical</strong>, then <strong>mark</strong> the folders as well as all their subfolders.</p>
-
-<ul>
-	<li>For example, folders <code>&quot;/a&quot;</code> and <code>&quot;/b&quot;</code> in the file structure below are identical. They (as well as their subfolders) should <strong>all</strong> be marked:
-	<ul>
-		<li><code>/a</code></li>
-		<li><code>/a/x</code></li>
-		<li><code>/a/x/y</code></li>
-		<li><code>/a/z</code></li>
-		<li><code>/b</code></li>
-		<li><code>/b/x</code></li>
-		<li><code>/b/x/y</code></li>
-		<li><code>/b/z</code></li>
-	</ul>
-	</li>
-	<li>However, if the file structure also included the path <code>&quot;/b/w&quot;</code>, then the folders <code>&quot;/a&quot;</code> and <code>&quot;/b&quot;</code> would not be identical. Note that <code>&quot;/a/x&quot;</code> and <code>&quot;/b/x&quot;</code> would still be considered identical even with the added folder.</li>
-</ul>
-
-<p>Once all the identical folders and their subfolders have been marked, the file system will <strong>delete</strong> all of them. The file system only runs the deletion once, so any folders that become identical after the initial deletion are not deleted.</p>
-
-<p>Return <em>the 2D array </em><code>ans</code> <em>containing the paths of the <strong>remaining</strong> folders after deleting all the marked folders. The paths may be returned in <strong>any</strong> order</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/19/lc-dupfolder1.jpg" style="width: 200px; height: 218px;" />
-<pre>
-<strong>Input:</strong> paths = [[&quot;a&quot;],[&quot;c&quot;],[&quot;d&quot;],[&quot;a&quot;,&quot;b&quot;],[&quot;c&quot;,&quot;b&quot;],[&quot;d&quot;,&quot;a&quot;]]
-<strong>Output:</strong> [[&quot;d&quot;],[&quot;d&quot;,&quot;a&quot;]]
-<strong>Explanation:</strong> The file structure is as shown.
-Folders &quot;/a&quot; and &quot;/c&quot; (and their subfolders) are marked for deletion because they both contain an empty
-folder named &quot;b&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/19/lc-dupfolder2.jpg" style="width: 200px; height: 355px;" />
-<pre>
-<strong>Input:</strong> paths = [[&quot;a&quot;],[&quot;c&quot;],[&quot;a&quot;,&quot;b&quot;],[&quot;c&quot;,&quot;b&quot;],[&quot;a&quot;,&quot;b&quot;,&quot;x&quot;],[&quot;a&quot;,&quot;b&quot;,&quot;x&quot;,&quot;y&quot;],[&quot;w&quot;],[&quot;w&quot;,&quot;y&quot;]]
-<strong>Output:</strong> [[&quot;c&quot;],[&quot;c&quot;,&quot;b&quot;],[&quot;a&quot;],[&quot;a&quot;,&quot;b&quot;]]
-<strong>Explanation: </strong>The file structure is as shown. 
-Folders &quot;/a/b/x&quot; and &quot;/w&quot; (and their subfolders) are marked for deletion because they both contain an empty folder named &quot;y&quot;.
-Note that folders &quot;/a&quot; and &quot;/c&quot; are identical after the deletion, but they are not deleted because they were not marked beforehand.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/19/lc-dupfolder3.jpg" style="width: 200px; height: 201px;" />
-<pre>
-<strong>Input:</strong> paths = [[&quot;a&quot;,&quot;b&quot;],[&quot;c&quot;,&quot;d&quot;],[&quot;c&quot;],[&quot;a&quot;]]
-<strong>Output:</strong> [[&quot;c&quot;],[&quot;c&quot;,&quot;d&quot;],[&quot;a&quot;],[&quot;a&quot;,&quot;b&quot;]]
-<strong>Explanation:</strong> All folders are unique in the file system.
-Note that the returned array can be in a different order as the order does not matter.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= paths.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= paths[i].length &lt;= 500</code></li>
-	<li><code>1 &lt;= paths[i][j].length &lt;= 10</code></li>
-	<li><code>1 &lt;= sum(paths[i][j].length) &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>path[i][j]</code> consists of lowercase English letters.</li>
-	<li>No two paths lead to the same folder.</li>
-	<li>For any folder not at the root level, its parent folder will also be in the input.</li>
-</ul>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we use a trie to build the folder structure?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we utilize hashing to hash the folder structures?
-</details>
diff --git a/problems/delete-leaves-with-a-given-value/README.md b/problems/delete-leaves-with-a-given-value/README.md
deleted file mode 100644
index 1b4d423df..000000000
--- a/problems/delete-leaves-with-a-given-value/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../print-words-vertically "Print Words Vertically")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-taps-to-open-to-water-a-garden "Minimum Number of Taps to Open to Water a Garden")
-
-## [1325. Delete Leaves With a Given Value (Medium)](https://leetcode.com/problems/delete-leaves-with-a-given-value "删除给定值的叶子节点")
-
-<p>Given a binary tree <code>root</code> and an integer <code>target</code>, delete all the <strong>leaf nodes</strong> with value <code>target</code>.</p>
-
-<p>Note that once you delete a leaf node with value <code>target</code><strong>, </strong>if its parent node becomes a leaf node and has the value <code>target</code>, it should also be deleted (you need to continue doing that until you cannot).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/01/09/sample_1_1684.png" style="width: 500px; height: 112px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,2,3,2,null,2,4], target = 2
-<strong>Output:</strong> [1,null,3,null,4]
-<strong>Explanation:</strong> Leaf nodes in green with value (target = 2) are removed (Picture in left). 
-After removing, new nodes become leaf nodes with value (target = 2) (Picture in center).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/01/09/sample_2_1684.png" style="width: 400px; height: 154px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,3,3,3,2], target = 3
-<strong>Output:</strong> [1,3,null,null,2]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/01/15/sample_3_1684.png" style="width: 500px; height: 166px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,2,null,2,null,2], target = 2
-<strong>Output:</strong> [1]
-<strong>Explanation:</strong> Leaf nodes in green with value (target = 2) are removed at each step.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 3000]</code>.</li>
-	<li><code>1 &lt;= Node.val, target &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use the DFS to reconstruct the tree such that no leaf node is equal to the target. If the leaf node is equal to the target, return an empty object instead.
-</details>
diff --git a/problems/delete-n-nodes-after-m-nodes-of-a-linked-list/README.md b/problems/delete-n-nodes-after-m-nodes-of-a-linked-list/README.md
deleted file mode 100644
index 9c97fa0c3..000000000
--- a/problems/delete-n-nodes-after-m-nodes-of-a-linked-list/README.md
+++ /dev/null
@@ -1,23 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../paint-house-iii "Paint House III")
-　　　　　　　　　　　　　　　　
-[Next >](../final-prices-with-a-special-discount-in-a-shop "Final Prices With a Special Discount in a Shop")
-
-## [1474. Delete N Nodes After M Nodes of a Linked List (Easy)](https://leetcode.com/problems/delete-n-nodes-after-m-nodes-of-a-linked-list "删除链表 M 个节点之后的 N 个节点")
-
-
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Traverse the Linked List, each time you need to delete the next n nodes connect the nodes previous deleting with the next node after deleting.
-</details>
diff --git a/problems/delete-node-in-a-bst/README.md b/problems/delete-node-in-a-bst/README.md
deleted file mode 100644
index c9ad5f2fd..000000000
--- a/problems/delete-node-in-a-bst/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../serialize-and-deserialize-bst "Serialize and Deserialize BST")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-characters-by-frequency "Sort Characters By Frequency")
-
-## [450. Delete Node in a BST (Medium)](https://leetcode.com/problems/delete-node-in-a-bst "删除二叉搜索树中的节点")
-
-<p>Given a root node reference of a BST and a key, delete the node with the given key in the BST. Return the root node reference (possibly updated) of the BST.</p>
-
-<p>Basically, the deletion can be divided into two stages:</p>
-
-<ol>
-	<li>Search for a node to remove.</li>
-	<li>If the node is found, delete the node.</li>
-</ol>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/04/del_node_1.jpg" style="width: 800px; height: 214px;" />
-<pre>
-<strong>Input:</strong> root = [5,3,6,2,4,null,7], key = 3
-<strong>Output:</strong> [5,4,6,2,null,null,7]
-<strong>Explanation:</strong> Given key to delete is 3. So we find the node with value 3 and delete it.
-One valid answer is [5,4,6,2,null,null,7], shown in the above BST.
-Please notice that another valid answer is [5,2,6,null,4,null,7] and it&#39;s also accepted.
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/04/del_node_supp.jpg" style="width: 350px; height: 255px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [5,3,6,2,4,null,7], key = 0
-<strong>Output:</strong> [5,3,6,2,4,null,7]
-<strong>Explanation:</strong> The tree does not contain a node with value = 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [], key = 0
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-	<li>Each node has a <strong>unique</strong> value.</li>
-	<li><code>root</code> is a valid binary search tree.</li>
-	<li><code>-10<sup>5</sup> &lt;= key &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you solve it with time complexity <code>O(height of tree)</code>?</p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Split BST](../split-bst) (Medium)
diff --git a/problems/delete-node-in-a-bst/delete_node_in_a_bst.go b/problems/delete-node-in-a-bst/delete_node_in_a_bst.go
deleted file mode 100644
index ad24d0e02..000000000
--- a/problems/delete-node-in-a-bst/delete_node_in_a_bst.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem450
diff --git a/problems/delete-node-in-a-bst/delete_node_in_a_bst_test.go b/problems/delete-node-in-a-bst/delete_node_in_a_bst_test.go
deleted file mode 100644
index ad24d0e02..000000000
--- a/problems/delete-node-in-a-bst/delete_node_in_a_bst_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem450
diff --git a/problems/delete-node-in-a-linked-list/README.md b/problems/delete-node-in-a-linked-list/README.md
deleted file mode 100644
index 232dc471f..000000000
--- a/problems/delete-node-in-a-linked-list/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lowest-common-ancestor-of-a-binary-tree "Lowest Common Ancestor of a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../product-of-array-except-self "Product of Array Except Self")
-
-## [237. Delete Node in a Linked List (Easy)](https://leetcode.com/problems/delete-node-in-a-linked-list "删除链表中的节点")
-
-<p>Write a function to <strong>delete a node</strong> in a singly-linked list. You will <strong>not</strong> be given access to the <code>head</code> of the list, instead you will be given access to <strong>the node to be deleted</strong> directly.</p>
-
-<p>It is <strong>guaranteed</strong> that the node to be deleted is <strong>not a tail node</strong> in the list.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/01/node1.jpg" style="width: 450px; height: 322px;" />
-<pre>
-<strong>Input:</strong> head = [4,5,1,9], node = 5
-<strong>Output:</strong> [4,1,9]
-<strong>Explanation: </strong>You are given the second node with value 5, the linked list should become 4 -&gt; 1 -&gt; 9 after calling your function.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/01/node2.jpg" style="width: 450px; height: 354px;" />
-<pre>
-<strong>Input:</strong> head = [4,5,1,9], node = 1
-<strong>Output:</strong> [4,5,9]
-<strong>Explanation: </strong>You are given the third node with value 1, the linked list should become 4 -&gt; 5 -&gt; 9 after calling your function.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1,2,3,4], node = 3
-<strong>Output:</strong> [1,2,4]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [0,1], node = 0
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [-3,5,-99], node = -3
-<strong>Output:</strong> [5,-99]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of the nodes in the given list is in the range <code>[2, 1000]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-	<li>The value of each node in the list is <strong>unique</strong>.</li>
-	<li>The <code>node</code> to be deleted is <strong>in the list</strong> and is <strong>not a tail</strong> node</li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Remove Linked List Elements](../remove-linked-list-elements) (Easy)
diff --git a/problems/delete-node-in-a-linked-list/delete_node_in_a_linked_list.go b/problems/delete-node-in-a-linked-list/delete_node_in_a_linked_list.go
deleted file mode 100644
index 9f981e47c..000000000
--- a/problems/delete-node-in-a-linked-list/delete_node_in_a_linked_list.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem237
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func deleteNode(node *ListNode) {
-	if node != nil && node.Next != nil {
-		node.Val = node.Next.Val
-		node.Next = node.Next.Next
-	}
-}
diff --git a/problems/delete-node-in-a-linked-list/delete_node_in_a_linked_list_test.go b/problems/delete-node-in-a-linked-list/delete_node_in_a_linked_list_test.go
deleted file mode 100644
index 0508d497e..000000000
--- a/problems/delete-node-in-a-linked-list/delete_node_in_a_linked_list_test.go
+++ /dev/null
@@ -1,56 +0,0 @@
-package problem237
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	node int
-	want []int
-}
-
-func TestDeleteNode(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{4, 5, 1, 9},
-			node: 5,
-			want: []int{4, 1, 9},
-		},
-		{
-			in:   []int{4, 5, 1, 9},
-			node: 1,
-			want: []int{4, 5, 9},
-		},
-		{
-			in:   []int{4, 5, 1, 9},
-			node: 4,
-			want: []int{5, 1, 9},
-		},
-		{
-			in:   []int{4, 5, 1, 9},
-			node: 9,
-			want: []int{4, 5, 1, 9},
-		},
-		{
-			in:   []int{4, 5, 1, 9},
-			node: 2,
-			want: []int{4, 5, 1, 9},
-		},
-	}
-	for _, tt := range tests {
-		head := kit.SliceInt2ListNode(tt.in)
-		node := head
-		for node != nil && node.Val != tt.node {
-			node = node.Next
-		}
-		deleteNode(node)
-		got := kit.ListNode2SliceInt(head)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/delete-nodes-and-return-forest/README.md b/problems/delete-nodes-and-return-forest/README.md
deleted file mode 100644
index 0260c45dd..000000000
--- a/problems/delete-nodes-and-return-forest/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../corporate-flight-bookings "Corporate Flight Bookings")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-nesting-depth-of-two-valid-parentheses-strings "Maximum Nesting Depth of Two Valid Parentheses Strings")
-
-## [1110. Delete Nodes And Return Forest (Medium)](https://leetcode.com/problems/delete-nodes-and-return-forest "删点成林")
-
-<p>Given the <code>root</code> of a binary tree, each node in the tree has a distinct value.</p>
-
-<p>After deleting all nodes with a value in <code>to_delete</code>, we are left with a forest (a disjoint union of trees).</p>
-
-<p>Return the roots of the trees in the remaining forest. You may return the result in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/07/01/screen-shot-2019-07-01-at-53836-pm.png" style="width: 237px; height: 150px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,6,7], to_delete = [3,5]
-<strong>Output:</strong> [[1,2,null,4],[6],[7]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,2,4,null,3], to_delete = [3]
-<strong>Output:</strong> [[1,2,4]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the given tree is at most <code>1000</code>.</li>
-	<li>Each node has a distinct value between <code>1</code> and <code>1000</code>.</li>
-	<li><code>to_delete.length &lt;= 1000</code></li>
-	<li><code>to_delete</code> contains distinct values between <code>1</code> and <code>1000</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/delete-nodes-and-return-forest/delete_nodes_and_return_forest.go b/problems/delete-nodes-and-return-forest/delete_nodes_and_return_forest.go
deleted file mode 100644
index 800173847..000000000
--- a/problems/delete-nodes-and-return-forest/delete_nodes_and_return_forest.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1110
diff --git a/problems/delete-operation-for-two-strings/README.md b/problems/delete-operation-for-two-strings/README.md
deleted file mode 100644
index 30e5ed60c..000000000
--- a/problems/delete-operation-for-two-strings/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kill-process "Kill Process")
-　　　　　　　　　　　　　　　　
-[Next >](../find-customer-referee "Find Customer Referee")
-
-## [583. Delete Operation for Two Strings (Medium)](https://leetcode.com/problems/delete-operation-for-two-strings "两个字符串的删除操作")
-
-<p>Given two strings <code>word1</code> and <code>word2</code>, return <em>the minimum number of <strong>steps</strong> required to make</em> <code>word1</code> <em>and</em> <code>word2</code> <em>the same</em>.</p>
-
-<p>In one <strong>step</strong>, you can delete exactly one character in either string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;sea&quot;, word2 = &quot;eat&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You need one step to make &quot;sea&quot; to &quot;ea&quot; and another step to make &quot;eat&quot; to &quot;ea&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;leetcode&quot;, word2 = &quot;etco&quot;
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word1.length, word2.length &lt;= 500</code></li>
-	<li><code>word1</code> and <code>word2</code> consist of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Edit Distance](../edit-distance) (Hard)
-  1. [Minimum ASCII Delete Sum for Two Strings](../minimum-ascii-delete-sum-for-two-strings) (Medium)
-  1. [Longest Common Subsequence](../longest-common-subsequence) (Medium)
diff --git a/problems/delete-operation-for-two-strings/delete_operation_for_two_strings.go b/problems/delete-operation-for-two-strings/delete_operation_for_two_strings.go
deleted file mode 100644
index ba746c9e5..000000000
--- a/problems/delete-operation-for-two-strings/delete_operation_for_two_strings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem583
diff --git a/problems/delete-operation-for-two-strings/delete_operation_for_two_strings_test.go b/problems/delete-operation-for-two-strings/delete_operation_for_two_strings_test.go
deleted file mode 100644
index ba746c9e5..000000000
--- a/problems/delete-operation-for-two-strings/delete_operation_for_two_strings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem583
diff --git a/problems/delete-the-middle-node-of-a-linked-list/README.md b/problems/delete-the-middle-node-of-a-linked-list/README.md
deleted file mode 100644
index e88e98744..000000000
--- a/problems/delete-the-middle-node-of-a-linked-list/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../finding-3-digit-even-numbers "Finding 3-Digit Even Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../step-by-step-directions-from-a-binary-tree-node-to-another "Step-By-Step Directions From a Binary Tree Node to Another")
-
-## [2095. Delete the Middle Node of a Linked List (Medium)](https://leetcode.com/problems/delete-the-middle-node-of-a-linked-list "删除链表的中间节点")
-
-<p>You are given the <code>head</code> of a linked list. <strong>Delete</strong> the <strong>middle node</strong>, and return <em>the</em> <code>head</code> <em>of the modified linked list</em>.</p>
-
-<p>The <strong>middle node</strong> of a linked list of size <code>n</code> is the <code>&lfloor;n / 2&rfloor;<sup>th</sup></code> node from the <b>start</b> using <strong>0-based indexing</strong>, where <code>&lfloor;x&rfloor;</code> denotes the largest integer less than or equal to <code>x</code>.</p>
-
-<ul>
-	<li>For <code>n</code> = <code>1</code>, <code>2</code>, <code>3</code>, <code>4</code>, and <code>5</code>, the middle nodes are <code>0</code>, <code>1</code>, <code>1</code>, <code>2</code>, and <code>2</code>, respectively.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/16/eg1drawio.png" style="width: 500px; height: 77px;" />
-<pre>
-<strong>Input:</strong> head = [1,3,4,7,1,2,6]
-<strong>Output:</strong> [1,3,4,1,2,6]
-<strong>Explanation:</strong>
-The above figure represents the given linked list. The indices of the nodes are written below.
-Since n = 7, node 3 with value 7 is the middle node, which is marked in red.
-We return the new list after removing this node. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/16/eg2drawio.png" style="width: 250px; height: 43px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4]
-<strong>Output:</strong> [1,2,4]
-<strong>Explanation:</strong>
-The above figure represents the given linked list.
-For n = 4, node 2 with value 3 is the middle node, which is marked in red.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/16/eg3drawio.png" style="width: 150px; height: 58px;" />
-<pre>
-<strong>Input:</strong> head = [2,1]
-<strong>Output:</strong> [2]
-<strong>Explanation:</strong>
-The above figure represents the given linked list.
-For n = 2, node 1 with value 1 is the middle node, which is marked in red.
-Node 0 with value 2 is the only node remaining after removing node 1.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If a point with a speed s moves n units in a given time, a point with speed 2 * s will move 2 * n units at the same time. Can you use this to find the middle node of a linked list?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you are given the middle node, the node before it, and the node after it, how can you modify the linked list?
-</details>
diff --git a/problems/delete-tree-nodes/README.md b/problems/delete-tree-nodes/README.md
deleted file mode 100644
index c355e3823..000000000
--- a/problems/delete-tree-nodes/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-interval "Remove Interval")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ships-in-a-rectangle "Number of Ships in a Rectangle")
-
-## [1273. Delete Tree Nodes (Medium)](https://leetcode.com/problems/delete-tree-nodes "删除树节点")
-
-<p>A tree rooted at node 0 is given as follows:</p>
-
-<ul>
-	<li>The number of nodes is <code>nodes</code>;</li>
-	<li>The value of the <code>i</code>-th node is <code>value[i]</code>;</li>
-	<li>The parent of the <code>i</code>-th node is <code>parent[i]</code>.</li>
-</ul>
-
-<p>Remove every subtree whose sum of values of nodes is zero.</p>
-
-<p>After doing so, return the number of nodes remaining in the tree.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/07/02/1421_sample_1.PNG" style="width: 403px; height: 347px;" /></p>
-
-<pre>
-<strong>Input:</strong> nodes = 7, parent = [-1,0,0,1,2,2,2], value = [1,-2,4,0,-2,-1,-1]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nodes &lt;= 10^4</code></li>
-	<li><code>-10^5 &lt;= value[i] &lt;= 10^5</code></li>
-	<li><code>parent.length == nodes</code></li>
-	<li><code>parent[0] == -1</code>&nbsp;which indicates that <code>0</code> is the root.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Traverse the tree using depth first search.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find for every node the sum of values of its sub-tree.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Traverse the tree again from the root and return once you reach a node with zero sum of values in its sub-tree.
-</details>
diff --git a/problems/delivering-boxes-from-storage-to-ports/README.md b/problems/delivering-boxes-from-storage-to-ports/README.md
deleted file mode 100644
index a72e47f52..000000000
--- a/problems/delivering-boxes-from-storage-to-ports/README.md
+++ /dev/null
@@ -1,99 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stone-game-vi "Stone Game VI")
-　　　　　　　　　　　　　　　　
-[Next >](../count-of-matches-in-tournament "Count of Matches in Tournament")
-
-## [1687. Delivering Boxes from Storage to Ports (Hard)](https://leetcode.com/problems/delivering-boxes-from-storage-to-ports "从仓库到码头运输箱子")
-
-<p>You have the task of delivering some boxes from storage to their ports using only one ship. However, this ship has a <strong>limit</strong> on the <strong>number of boxes</strong> and the <strong>total weight</strong> that it can carry.</p>
-
-<p>You are given an array <code>boxes</code>, where <code>boxes[i] = [ports<sub>​​i</sub>​, weight<sub>i</sub>]</code>, and three integers <code>portsCount</code>, <code>maxBoxes</code>, and <code>maxWeight</code>.</p>
-
-<ul>
-	<li><code>ports<sub>​​i</sub></code> is the port where you need to deliver the <code>i<sup>th</sup></code> box and <code>weights<sub>i</sub></code> is the weight of the <code>i<sup>th</sup></code> box.</li>
-	<li><code>portsCount</code> is the number of ports.</li>
-	<li><code>maxBoxes</code> and <code>maxWeight</code> are the respective box and weight limits of the ship.</li>
-</ul>
-
-<p>The boxes need to be delivered <strong>in the order they are given</strong>. The ship will follow these steps:</p>
-
-<ul>
-	<li>The ship will take some number of boxes from the <code>boxes</code> queue, not violating the <code>maxBoxes</code> and <code>maxWeight</code> constraints.</li>
-	<li>For each loaded box <strong>in order</strong>, the ship will make a <strong>trip</strong> to the port the box needs to be delivered to and deliver it. If the ship is already at the correct port, no <strong>trip</strong> is needed, and the box can immediately be delivered.</li>
-	<li>The ship then makes a return <strong>trip</strong> to storage to take more boxes from the queue.</li>
-</ul>
-
-<p>The ship must end at storage after all the boxes have been delivered.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of <strong>trips</strong> the ship needs to make to deliver all boxes to their respective ports.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxes = [[1,1],[2,1],[1,1]], portsCount = 2, maxBoxes = 3, maxWeight = 3
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The optimal strategy is as follows: 
-- The ship takes all the boxes in the queue, goes to port 1, then port 2, then port 1 again, then returns to storage. 4 trips.
-So the total number of trips is 4.
-Note that the first and third boxes cannot be delivered together because the boxes need to be delivered in order (i.e. the second box needs to be delivered at port 2 before the third box).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxes = [[1,2],[3,3],[3,1],[3,1],[2,4]], portsCount = 3, maxBoxes = 3, maxWeight = 6
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The optimal strategy is as follows: 
-- The ship takes the first box, goes to port 1, then returns to storage. 2 trips.
-- The ship takes the second, third and fourth boxes, goes to port 3, then returns to storage. 2 trips.
-- The ship takes the fifth box, goes to port 3, then returns to storage. 2 trips.
-So the total number of trips is 2 + 2 + 2 = 6.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxes = [[1,4],[1,2],[2,1],[2,1],[3,2],[3,4]], portsCount = 3, maxBoxes = 6, maxWeight = 7
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The optimal strategy is as follows:
-- The ship takes the first and second boxes, goes to port 1, then returns to storage. 2 trips.
-- The ship takes the third and fourth boxes, goes to port 2, then returns to storage. 2 trips.
-- The ship takes the fifth and sixth boxes, goes to port 3, then returns to storage. 2 trips.
-So the total number of trips is 2 + 2 + 2 = 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= boxes.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= portsCount, maxBoxes, maxWeight &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= ports<sub>​​i</sub> &lt;= portsCount</code></li>
-	<li><code>1 &lt;= weights<sub>i</sub> &lt;= maxWeight</code></li>
-</ul>
-
-### Related Topics
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Monotonic Queue](../../tag/monotonic-queue/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to think of the most basic dp which is n^2 now optimize it
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think of any range query data structure to optimize
-</details>
diff --git a/problems/department-highest-salary/README.md b/problems/department-highest-salary/README.md
deleted file mode 100644
index c9072c79e..000000000
--- a/problems/department-highest-salary/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../customers-who-never-order "Customers Who Never Order")
-　　　　　　　　　　　　　　　　
-[Next >](../department-top-three-salaries "Department Top Three Salaries")
-
-## [184. Department Highest Salary (Medium)](https://leetcode.com/problems/department-highest-salary "部门工资最高的员工")
-
-<p>Table: <code>Employee</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| Id           | int     |
-| Name         | varchar |
-| Salary       | int     |
-| DepartmentId | int     |
-+--------------+---------+
-Id is the primary key column for this table.
-DepartmentId is a foreign key of the ID from the <code>Department </code>table.
-Each row of this table indicates the ID, name, and salary of an employee. It also contains the ID of their department.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Table: <code>Department</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| Id          | int     |
-| Name        | varchar |
-+-------------+---------+
-Id is the primary key column for this table.
-Each row of this table indicates the ID of a department and its name.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find employees who have the highest salary in each of the departments.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Employee table:
-+----+-------+--------+--------------+
-| Id | Name  | Salary | DepartmentId |
-+----+-------+--------+--------------+
-| 1  | Joe   | 70000  | 1            |
-| 2  | Jim   | 90000  | 1            |
-| 3  | Henry | 80000  | 2            |
-| 4  | Sam   | 60000  | 2            |
-| 5  | Max   | 90000  | 1            |
-+----+-------+--------+--------------+
-Department table:
-+----+-------+
-| Id | Name  |
-+----+-------+
-| 1  | IT    |
-| 2  | Sales |
-+----+-------+
-<strong>Output:</strong> 
-+------------+----------+--------+
-| Department | Employee | Salary |
-+------------+----------+--------+
-| IT         | Jim      | 90000  |
-| Sales      | Henry    | 80000  |
-| IT         | Max      | 90000  |
-+------------+----------+--------+
-<strong>Explanation:</strong> Max and Jim both have the highest salary in the IT department and Henry has the highest salary in the Sales department.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/department-highest-salary/department_highest_salary.sql b/problems/department-highest-salary/department_highest_salary.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/department-highest-salary/department_highest_salary.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/department-highest-salary/mysql_schemas.sql b/problems/department-highest-salary/mysql_schemas.sql
deleted file mode 100644
index 2fb3b6485..000000000
--- a/problems/department-highest-salary/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Employee (Id int, Name varchar(255), Salary int, DepartmentId int);
-Create table If Not Exists Department (Id int, Name varchar(255));
-Truncate table Employee;
-insert into Employee (Id, Name, Salary, DepartmentId) values ('1', 'Joe', '70000', '1');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('2', 'Jim', '90000', '1');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('3', 'Henry', '80000', '2');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('4', 'Sam', '60000', '2');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('5', 'Max', '90000', '1');
-Truncate table Department;
-insert into Department (Id, Name) values ('1', 'IT');
-insert into Department (Id, Name) values ('2', 'Sales');
diff --git a/problems/department-top-three-salaries/README.md b/problems/department-top-three-salaries/README.md
deleted file mode 100644
index 3badb634b..000000000
--- a/problems/department-top-three-salaries/README.md
+++ /dev/null
@@ -1,103 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../department-highest-salary "Department Highest Salary")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-words-in-a-string-ii "Reverse Words in a String II")
-
-## [185. Department Top Three Salaries (Hard)](https://leetcode.com/problems/department-top-three-salaries "部门工资前三高的所有员工")
-
-<p>Table: <code>Employee</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| Id           | int     |
-| Name         | varchar |
-| Salary       | int     |
-| DepartmentId | int     |
-+--------------+---------+
-Id is the primary key column for this table.
-DepartmentId is a foreign key of the ID from the <code>Department </code>table.
-Each row of this table indicates the ID, name, and salary of an employee. It also contains the ID of their department.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Table: <code>Department</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| Id          | int     |
-| Name        | varchar |
-+-------------+---------+
-Id is the primary key column for this table.
-Each row of this table indicates the ID of a department and its name.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>A company&#39;s executives are interested in seeing who earns the most money in each of the company&#39;s departments. A <strong>high earner</strong> in a department is an employee who has a salary in the <strong>top three unique</strong> salaries for that department.</p>
-
-<p>Write an SQL query to find the employees who are <strong>high earners</strong> in each of the departments.</p>
-
-<p>Return the result table <strong>in any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Employee table:
-+----+-------+--------+--------------+
-| Id | Name  | Salary | DepartmentId |
-+----+-------+--------+--------------+
-| 1  | Joe   | 85000  | 1            |
-| 2  | Henry | 80000  | 2            |
-| 3  | Sam   | 60000  | 2            |
-| 4  | Max   | 90000  | 1            |
-| 5  | Janet | 69000  | 1            |
-| 6  | Randy | 85000  | 1            |
-| 7  | Will  | 70000  | 1            |
-+----+-------+--------+--------------+
-Department table:
-+----+-------+
-| Id | Name  |
-+----+-------+
-| 1  | IT    |
-| 2  | Sales |
-+----+-------+
-<strong>Output:</strong> 
-+------------+----------+--------+
-| Department | Employee | Salary |
-+------------+----------+--------+
-| IT         | Max      | 90000  |
-| IT         | Joe      | 85000  |
-| IT         | Randy    | 85000  |
-| IT         | Will     | 70000  |
-| Sales      | Henry    | 80000  |
-| Sales      | Sam      | 60000  |
-+------------+----------+--------+
-<strong>Explanation:</strong> 
-In the IT department:
-- Max earns the highest unique salary
-- Both Randy and Joe earn the second-highest unique salary
-- Will earns the third-highest unique salary
-
-In the Sales department:
-- Henry earns the highest salary
-- Sam earns the second-highest salary
-- There is no third-highest salary as there are only two employees
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/department-top-three-salaries/department_top_three_salaries.sql b/problems/department-top-three-salaries/department_top_three_salaries.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/department-top-three-salaries/department_top_three_salaries.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/department-top-three-salaries/mysql_schemas.sql b/problems/department-top-three-salaries/mysql_schemas.sql
deleted file mode 100644
index 24a47da59..000000000
--- a/problems/department-top-three-salaries/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Employee (Id int, Name varchar(255), Salary int, DepartmentId int);
-Create table If Not Exists Department (Id int, Name varchar(255));
-Truncate table Employee;
-insert into Employee (Id, Name, Salary, DepartmentId) values ('1', 'Joe', '85000', '1');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('2', 'Henry', '80000', '2');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('3', 'Sam', '60000', '2');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('4', 'Max', '90000', '1');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('5', 'Janet', '69000', '1');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('6', 'Randy', '85000', '1');
-insert into Employee (Id, Name, Salary, DepartmentId) values ('7', 'Will', '70000', '1');
-Truncate table Department;
-insert into Department (Id, Name) values ('1', 'IT');
-insert into Department (Id, Name) values ('2', 'Sales');
diff --git a/problems/depth-of-bst-given-insertion-order/README.md b/problems/depth-of-bst-given-insertion-order/README.md
deleted file mode 100644
index ecf971b20..000000000
--- a/problems/depth-of-bst-given-insertion-order/README.md
+++ /dev/null
@@ -1,31 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-a-peak-element-ii "Find a Peak Element II")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-odd-number-in-string "Largest Odd Number in String")
-
-## [1902. Depth of BST Given Insertion Order (Medium)](https://leetcode.com/problems/depth-of-bst-given-insertion-order "给定二叉搜索树的插入顺序求深度")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There are at most 2 possible places where a new node can be inserted?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we keep track of the depth of each node?
-</details>
diff --git a/problems/describe-the-painting/README.md b/problems/describe-the-painting/README.md
deleted file mode 100644
index ac2cbbea4..000000000
--- a/problems/describe-the-painting/README.md
+++ /dev/null
@@ -1,101 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-the-smallest-unoccupied-chair "The Number of the Smallest Unoccupied Chair")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-visible-people-in-a-queue "Number of Visible People in a Queue")
-
-## [1943. Describe the Painting (Medium)](https://leetcode.com/problems/describe-the-painting "描述绘画结果")
-
-<p>There is a long and thin painting that can be represented by a number line. The painting was painted with multiple overlapping segments where each segment was painted with a <strong>unique</strong> color. You are given a 2D integer array <code>segments</code>, where <code>segments[i] = [start<sub>i</sub>, end<sub>i</sub>, color<sub>i</sub>]</code> represents the <strong>half-closed segment</strong> <code>[start<sub>i</sub>, end<sub>i</sub>)</code> with <code>color<sub>i</sub></code> as the color.</p>
-
-<p>The colors in the overlapping segments of the painting were <strong>mixed</strong> when it was painted. When two or more colors mix, they form a new color that can be represented as a <strong>set</strong> of mixed colors.</p>
-
-<ul>
-	<li>For example, if colors <code>2</code>, <code>4</code>, and <code>6</code> are mixed, then the resulting mixed color is <code>{2,4,6}</code>.</li>
-</ul>
-
-<p>For the sake of simplicity, you should only output the <strong>sum</strong> of the elements in the set rather than the full set.</p>
-
-<p>You want to <strong>describe</strong> the painting with the <strong>minimum</strong> number of non-overlapping <strong>half-closed segments</strong> of these mixed colors. These segments can be represented by the 2D array <code>painting</code> where <code>painting[j] = [left<sub>j</sub>, right<sub>j</sub>, mix<sub>j</sub>]</code> describes a <strong>half-closed segment</strong> <code>[left<sub>j</sub>, right<sub>j</sub>)</code> with the mixed color <strong>sum</strong> of <code>mix<sub>j</sub></code>.</p>
-
-<ul>
-	<li>For example, the painting created with <code>segments = [[1,4,5],[1,7,7]]</code> can be described by <code>painting = [[1,4,12],[4,7,7]]</code> because:
-	<ul>
-		<li><code>[1,4)</code> is colored <code>{5,7}</code> (with a sum of <code>12</code>) from both the first and second segments.</li>
-		<li><code>[4,7)</code> is colored <code>{7}</code> from only the second segment.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <em>the 2D array </em><code>painting</code><em> describing the finished painting (excluding any parts that are <strong>not </strong>painted). You may return the segments in <strong>any order</strong></em>.</p>
-
-<p>A <strong>half-closed segment</strong> <code>[a, b)</code> is the section of the number line between points <code>a</code> and <code>b</code> <strong>including</strong> point <code>a</code> and <strong>not including</strong> point <code>b</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/18/1.png" style="width: 529px; height: 241px;" />
-<pre>
-<strong>Input:</strong> segments = [[1,4,5],[4,7,7],[1,7,9]]
-<strong>Output:</strong> [[1,4,14],[4,7,16]]
-<strong>Explanation: </strong>The painting can be described as follows:
-- [1,4) is colored {5,9} (with a sum of 14) from the first and third segments.
-- [4,7) is colored {7,9} (with a sum of 16) from the second and third segments.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/18/2.png" style="width: 532px; height: 219px;" />
-<pre>
-<strong>Input:</strong> segments = [[1,7,9],[6,8,15],[8,10,7]]
-<strong>Output:</strong> [[1,6,9],[6,7,24],[7,8,15],[8,10,7]]
-<strong>Explanation: </strong>The painting can be described as follows:
-- [1,6) is colored 9 from the first segment.
-- [6,7) is colored {9,15} (with a sum of 24) from the first and second segments.
-- [7,8) is colored 15 from the second segment.
-- [8,10) is colored 7 from the third segment.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/04/c1.png" style="width: 529px; height: 289px;" />
-<pre>
-<strong>Input:</strong> segments = [[1,4,5],[1,4,7],[4,7,1],[4,7,11]]
-<strong>Output:</strong> [[1,4,12],[4,7,12]]
-<strong>Explanation: </strong>The painting can be described as follows:
-- [1,4) is colored {5,7} (with a sum of 12) from the first and second segments.
-- [4,7) is colored {1,11} (with a sum of 12) from the third and fourth segments.
-Note that returning a single segment [1,7) is incorrect because the mixed color sets are different.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= segments.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>segments[i].length == 3</code></li>
-	<li><code>1 &lt;= start<sub>i</sub> &lt; end<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= color<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li>Each <code>color<sub>i</sub></code> is distinct.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Average Height of Buildings in Each Segment](../average-height-of-buildings-in-each-segment) (Medium)
-  1. [Amount of New Area Painted Each Day](../amount-of-new-area-painted-each-day) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we sort the segments in a way to help solve the problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we dynamically keep track of the sum of the current segment(s)?
-</details>
diff --git a/problems/design-a-file-sharing-system/README.md b/problems/design-a-file-sharing-system/README.md
deleted file mode 100644
index ff0ae03e8..000000000
--- a/problems/design-a-file-sharing-system/README.md
+++ /dev/null
@@ -1,34 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-value-of-equation "Max Value of Equation")
-　　　　　　　　　　　　　　　　
-[Next >](../countries-you-can-safely-invest-in "Countries You Can Safely Invest In")
-
-## [1500. Design a File Sharing System (Medium)](https://leetcode.com/problems/design-a-file-sharing-system "设计文件分享系统")
-
-
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Similar Questions
-  1. [Design Twitter](../design-twitter) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to solve it by keeping for each file chunk, the users who have this chunk.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to solve it by keeping all the users in the system with their owned chunks, and when you request a chunk, check all users for it.
-</details>
diff --git a/problems/design-a-leaderboard/README.md b/problems/design-a-leaderboard/README.md
deleted file mode 100644
index 8d0f86afa..000000000
--- a/problems/design-a-leaderboard/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../array-transformation "Array Transformation")
-　　　　　　　　　　　　　　　　
-[Next >](../tree-diameter "Tree Diameter")
-
-## [1244. Design A Leaderboard (Medium)](https://leetcode.com/problems/design-a-leaderboard "力扣排行榜")
-
-<p>Design a Leaderboard class, which has 3 functions:</p>
-
-<ol>
-	<li><code>addScore(playerId, score)</code>: Update the leaderboard by adding <code>score</code> to the given player&#39;s score. If there is no player with such id in the leaderboard, add him to the leaderboard with the given <code>score</code>.</li>
-	<li><code>top(K)</code>: Return the score sum of the top <code>K</code> players.</li>
-	<li><code>reset(playerId)</code>: Reset the score of the player with the given id&nbsp;to 0. It is guaranteed that the player was added to the leaderboard before calling this function.</li>
-</ol>
-
-<p>Initially, the leaderboard is empty.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<b>Input: </b>
-[&quot;Leaderboard&quot;,&quot;addScore&quot;,&quot;addScore&quot;,&quot;addScore&quot;,&quot;addScore&quot;,&quot;addScore&quot;,&quot;top&quot;,&quot;reset&quot;,&quot;reset&quot;,&quot;addScore&quot;,&quot;top&quot;]
-[[],[1,73],[2,56],[3,39],[4,51],[5,4],[1],[1],[2],[2,51],[3]]
-<b>Output: </b>
-[null,null,null,null,null,null,73,null,null,null,141]
-
-<b>Explanation: </b>
-Leaderboard leaderboard = new Leaderboard ();
-leaderboard.addScore(1,73);   // leaderboard = [[1,73]];
-leaderboard.addScore(2,56);   // leaderboard = [[1,73],[2,56]];
-leaderboard.addScore(3,39);   // leaderboard = [[1,73],[2,56],[3,39]];
-leaderboard.addScore(4,51);   // leaderboard = [[1,73],[2,56],[3,39],[4,51]];
-leaderboard.addScore(5,4);    // leaderboard = [[1,73],[2,56],[3,39],[4,51],[5,4]];
-leaderboard.top(1);           // returns 73;
-leaderboard.reset(1);         // leaderboard = [[2,56],[3,39],[4,51],[5,4]];
-leaderboard.reset(2);         // leaderboard = [[3,39],[4,51],[5,4]];
-leaderboard.addScore(2,51);   // leaderboard = [[2,51],[3,39],[4,51],[5,4]];
-leaderboard.top(3);           // returns 141 = 51 + 51 + 39;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= playerId, K &lt;= 10000</code></li>
-	<li>It&#39;s guaranteed that <code>K</code> is less than or equal to the current number of players.</li>
-	<li><code>1 &lt;= score&nbsp;&lt;= 100</code></li>
-	<li>There will be at most <code>1000</code>&nbsp;function calls.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What data structure can we use to keep the players' data?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep a map (dictionary) of player scores.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For each top(K) function call, find the maximum K scores and add them.
-</details>
diff --git a/problems/design-a-stack-with-increment-operation/README.md b/problems/design-a-stack-with-increment-operation/README.md
deleted file mode 100644
index 136646831..000000000
--- a/problems/design-a-stack-with-increment-operation/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lucky-numbers-in-a-matrix "Lucky Numbers in a Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../balance-a-binary-search-tree "Balance a Binary Search Tree")
-
-## [1381. Design a Stack With Increment Operation (Medium)](https://leetcode.com/problems/design-a-stack-with-increment-operation "设计一个支持增量操作的栈")
-
-<p>Design a stack which supports the following operations.</p>
-
-<p>Implement the <code>CustomStack</code> class:</p>
-
-<ul>
-	<li><code>CustomStack(int maxSize)</code> Initializes the object with <code>maxSize</code> which is the maximum number of elements in the stack or do nothing if the stack reached the <code>maxSize</code>.</li>
-	<li><code>void push(int x)</code>&nbsp;Adds <code>x</code> to the top of the stack if the stack hasn&#39;t reached the <code>maxSize</code>.</li>
-	<li><code>int pop()</code>&nbsp;Pops and returns the top of stack or <strong>-1</strong> if the stack is empty.</li>
-	<li><code>void inc(int k, int val)</code> Increments the bottom <code>k</code> elements of the stack by <code>val</code>. If there are less than <code>k</code> elements in the stack, just increment all the elements in the stack.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;CustomStack&quot;,&quot;push&quot;,&quot;push&quot;,&quot;pop&quot;,&quot;push&quot;,&quot;push&quot;,&quot;push&quot;,&quot;increment&quot;,&quot;increment&quot;,&quot;pop&quot;,&quot;pop&quot;,&quot;pop&quot;,&quot;pop&quot;]
-[[3],[1],[2],[],[2],[3],[4],[5,100],[2,100],[],[],[],[]]
-<strong>Output</strong>
-[null,null,null,2,null,null,null,null,null,103,202,201,-1]
-<strong>Explanation</strong>
-CustomStack customStack = new CustomStack(3); // Stack is Empty []
-customStack.push(1);                          // stack becomes [1]
-customStack.push(2);                          // stack becomes [1, 2]
-customStack.pop();                            // return 2 --&gt; Return top of the stack 2, stack becomes [1]
-customStack.push(2);                          // stack becomes [1, 2]
-customStack.push(3);                          // stack becomes [1, 2, 3]
-customStack.push(4);                          // stack still [1, 2, 3], Don&#39;t add another elements as size is 4
-customStack.increment(5, 100);                // stack becomes [101, 102, 103]
-customStack.increment(2, 100);                // stack becomes [201, 202, 103]
-customStack.pop();                            // return 103 --&gt; Return top of the stack 103, stack becomes [201, 202]
-customStack.pop();                            // return 202 --&gt; Return top of the stack 102, stack becomes [201]
-customStack.pop();                            // return 201 --&gt; Return top of the stack 101, stack becomes []
-customStack.pop();                            // return -1 --&gt; Stack is empty return -1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= maxSize &lt;= 1000</code></li>
-	<li><code>1 &lt;= x &lt;= 1000</code></li>
-	<li><code>1 &lt;= k &lt;= 1000</code></li>
-	<li><code>0 &lt;= val &lt;= 100</code></li>
-	<li>At most&nbsp;<code>1000</code>&nbsp;calls will be made to each method of <code>increment</code>, <code>push</code> and <code>pop</code> each separately.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use an array to represent the stack. Push will add new integer to the array. Pop removes the last element in the array and increment will add val to the first k elements of the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-This solution run in O(1) per push and pop and O(k) per increment.
-</details>
diff --git a/problems/design-add-and-search-words-data-structure/README.md b/problems/design-add-and-search-words-data-structure/README.md
deleted file mode 100644
index fae9b6c28..000000000
--- a/problems/design-add-and-search-words-data-structure/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../course-schedule-ii "Course Schedule II")
-　　　　　　　　　　　　　　　　
-[Next >](../word-search-ii "Word Search II")
-
-## [211. Design Add and Search Words Data Structure (Medium)](https://leetcode.com/problems/design-add-and-search-words-data-structure "添加与搜索单词 - 数据结构设计")
-
-<p>Design a data structure that supports adding new words and finding if a string matches any previously added string.</p>
-
-<p>Implement the <code>WordDictionary</code> class:</p>
-
-<ul>
-	<li><code>WordDictionary()</code>&nbsp;Initializes the object.</li>
-	<li><code>void addWord(word)</code> Adds <code>word</code> to the data structure, it can be matched later.</li>
-	<li><code>bool search(word)</code>&nbsp;Returns <code>true</code> if there is any string in the data structure that matches <code>word</code>&nbsp;or <code>false</code> otherwise. <code>word</code> may contain dots <code>&#39;.&#39;</code> where dots can be matched with any letter.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;WordDictionary&quot;,&quot;addWord&quot;,&quot;addWord&quot;,&quot;addWord&quot;,&quot;search&quot;,&quot;search&quot;,&quot;search&quot;,&quot;search&quot;]
-[[],[&quot;bad&quot;],[&quot;dad&quot;],[&quot;mad&quot;],[&quot;pad&quot;],[&quot;bad&quot;],[&quot;.ad&quot;],[&quot;b..&quot;]]
-<strong>Output</strong>
-[null,null,null,null,false,true,true,true]
-
-<strong>Explanation</strong>
-WordDictionary wordDictionary = new WordDictionary();
-wordDictionary.addWord(&quot;bad&quot;);
-wordDictionary.addWord(&quot;dad&quot;);
-wordDictionary.addWord(&quot;mad&quot;);
-wordDictionary.search(&quot;pad&quot;); // return False
-wordDictionary.search(&quot;bad&quot;); // return True
-wordDictionary.search(&quot;.ad&quot;); // return True
-wordDictionary.search(&quot;b..&quot;); // return True
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length &lt;= 500</code></li>
-	<li><code>word</code> in <code>addWord</code> consists lower-case English letters.</li>
-	<li><code>word</code> in <code>search</code> consist of&nbsp; <code>&#39;.&#39;</code> or lower-case English letters.</li>
-	<li>At most <code>50000</code>&nbsp;calls will be made to <code>addWord</code>&nbsp;and <code>search</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Similar Questions
-  1. [Implement Trie (Prefix Tree)](../implement-trie-prefix-tree) (Medium)
-  1. [Prefix and Suffix Search](../prefix-and-suffix-search) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You should be familiar with how a Trie works. If not, please work on this problem: <a href="https://leetcode.com/problems/implement-trie-prefix-tree/">Implement Trie (Prefix Tree)</a> first.
-</details>
diff --git a/problems/design-an-expression-tree-with-evaluate-function/README.md b/problems/design-an-expression-tree-with-evaluate-function/README.md
deleted file mode 100644
index 1a7b65ecc..000000000
--- a/problems/design-an-expression-tree-with-evaluate-function/README.md
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../graph-connectivity-with-threshold "Graph Connectivity With Threshold")
-　　　　　　　　　　　　　　　　
-[Next >](../slowest-key "Slowest Key")
-
-## [1628. Design an Expression Tree With Evaluate Function (Medium)](https://leetcode.com/problems/design-an-expression-tree-with-evaluate-function "设计带解析函数的表达式树")
-
-
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Apply the concept of Polymorphism to get a good design
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Implement the Node class using NumericNode and OperatorNode classes.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-NumericNode only maintains the value and evaluate returns this value.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-OperatorNode Maintains the left and right nodes representing the left and right operands, and the evaluate function applies the operator to them.
-</details>
diff --git a/problems/design-an-ordered-stream/README.md b/problems/design-an-ordered-stream/README.md
deleted file mode 100644
index 33f5fb0c2..000000000
--- a/problems/design-an-ordered-stream/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distribute-repeating-integers "Distribute Repeating Integers")
-　　　　　　　　　　　　　　　　
-[Next >](../determine-if-two-strings-are-close "Determine if Two Strings Are Close")
-
-## [1656. Design an Ordered Stream (Easy)](https://leetcode.com/problems/design-an-ordered-stream "设计有序流")
-
-<p>There is a stream of <code>n</code> <code>(idKey, value)</code> pairs arriving in an <strong>arbitrary</strong> order, where <code>idKey</code> is an integer between <code>1</code> and <code>n</code> and <code>value</code> is a string. No two pairs have the same <code>id</code>.</p>
-
-<p>Design a stream that returns the values in <strong>increasing order of their IDs</strong> by returning a <strong>chunk</strong> (list) of values after each insertion. The concatenation of all the <strong>chunks</strong> should result in a list of the sorted values.</p>
-
-<p>Implement the <code>OrderedStream</code> class:</p>
-
-<ul>
-	<li><code>OrderedStream(int n)</code> Constructs the stream to take <code>n</code> values.</li>
-	<li><code>String[] insert(int idKey, String value)</code> Inserts the pair <code>(idKey, value)</code> into the stream, then returns the <strong>largest possible chunk</strong> of currently inserted values that appear next in the order.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/11/10/q1.gif" style="width: 682px; height: 240px;" /></strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;OrderedStream&quot;, &quot;insert&quot;, &quot;insert&quot;, &quot;insert&quot;, &quot;insert&quot;, &quot;insert&quot;]
-[[5], [3, &quot;ccccc&quot;], [1, &quot;aaaaa&quot;], [2, &quot;bbbbb&quot;], [5, &quot;eeeee&quot;], [4, &quot;ddddd&quot;]]
-<strong>Output</strong>
-[null, [], [&quot;aaaaa&quot;], [&quot;bbbbb&quot;, &quot;ccccc&quot;], [], [&quot;ddddd&quot;, &quot;eeeee&quot;]]
-
-<strong>Explanation</strong>
-// Note that the values ordered by ID is [&quot;aaaaa&quot;, &quot;bbbbb&quot;, &quot;ccccc&quot;, &quot;ddddd&quot;, &quot;eeeee&quot;].
-OrderedStream os = new OrderedStream(5);
-os.insert(3, &quot;ccccc&quot;); // Inserts (3, &quot;ccccc&quot;), returns [].
-os.insert(1, &quot;aaaaa&quot;); // Inserts (1, &quot;aaaaa&quot;), returns [&quot;aaaaa&quot;].
-os.insert(2, &quot;bbbbb&quot;); // Inserts (2, &quot;bbbbb&quot;), returns [&quot;bbbbb&quot;, &quot;ccccc&quot;].
-os.insert(5, &quot;eeeee&quot;); // Inserts (5, &quot;eeeee&quot;), returns [].
-os.insert(4, &quot;ddddd&quot;); // Inserts (4, &quot;ddddd&quot;), returns [&quot;ddddd&quot;, &quot;eeeee&quot;].
-// Concatentating all the chunks returned:
-// [] + [&quot;aaaaa&quot;] + [&quot;bbbbb&quot;, &quot;ccccc&quot;] + [] + [&quot;ddddd&quot;, &quot;eeeee&quot;] = [&quot;aaaaa&quot;, &quot;bbbbb&quot;, &quot;ccccc&quot;, &quot;ddddd&quot;, &quot;eeeee&quot;]
-// The resulting order is the same as the order above.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= id &lt;= n</code></li>
-	<li><code>value.length == 5</code></li>
-	<li><code>value</code>&nbsp;consists only of lowercase letters.</li>
-	<li>Each call to <code>insert</code>&nbsp;will have a unique <code>id.</code></li>
-	<li>Exactly <code>n</code> calls will be made to <code>insert</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Maintain the next id that should be outputted.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Maintain the ids that were inserted in the stream.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Per each insert, make a loop where you check if the id that has the turn has been inserted, and if so increment the id that has the turn and continue the loop, else break.
-</details>
diff --git a/problems/design-authentication-manager/README.md b/problems/design-authentication-manager/README.md
deleted file mode 100644
index 9a190e5aa..000000000
--- a/problems/design-authentication-manager/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../second-largest-digit-in-a-string "Second Largest Digit in a String")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-consecutive-values-you-can-make "Maximum Number of Consecutive Values You Can Make")
-
-## [1797. Design Authentication Manager (Medium)](https://leetcode.com/problems/design-authentication-manager "设计一个验证系统")
-
-<p>There is an authentication system that works with authentication tokens. For each session, the user will receive a new authentication token that will expire <code>timeToLive</code> seconds after the <code>currentTime</code>. If the token is renewed, the expiry time will be <b>extended</b> to expire <code>timeToLive</code> seconds after the (potentially different) <code>currentTime</code>.</p>
-
-<p>Implement the <code>AuthenticationManager</code> class:</p>
-
-<ul>
-	<li><code>AuthenticationManager(int timeToLive)</code> constructs the <code>AuthenticationManager</code> and sets the <code>timeToLive</code>.</li>
-	<li><code>generate(string tokenId, int currentTime)</code> generates a new token with the given <code>tokenId</code> at the given <code>currentTime</code> in seconds.</li>
-	<li><code>renew(string tokenId, int currentTime)</code> renews the <strong>unexpired</strong> token with the given <code>tokenId</code> at the given <code>currentTime</code> in seconds. If there are no unexpired tokens with the given <code>tokenId</code>, the request is ignored, and nothing happens.</li>
-	<li><code>countUnexpiredTokens(int currentTime)</code> returns the number of <strong>unexpired</strong> tokens at the given currentTime.</li>
-</ul>
-
-<p>Note that if a token expires at time <code>t</code>, and another action happens on time <code>t</code> (<code>renew</code> or <code>countUnexpiredTokens</code>), the expiration takes place <strong>before</strong> the other actions.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/25/copy-of-pc68_q2.png" style="width: 500px; height: 287px;" />
-<pre>
-<strong>Input</strong>
-[&quot;AuthenticationManager&quot;, &quot;<code>renew</code>&quot;, &quot;generate&quot;, &quot;<code>countUnexpiredTokens</code>&quot;, &quot;generate&quot;, &quot;<code>renew</code>&quot;, &quot;<code>renew</code>&quot;, &quot;<code>countUnexpiredTokens</code>&quot;]
-[[5], [&quot;aaa&quot;, 1], [&quot;aaa&quot;, 2], [6], [&quot;bbb&quot;, 7], [&quot;aaa&quot;, 8], [&quot;bbb&quot;, 10], [15]]
-<strong>Output</strong>
-[null, null, null, 1, null, null, null, 0]
-
-<strong>Explanation</strong>
-AuthenticationManager authenticationManager = new AuthenticationManager(5); // Constructs the AuthenticationManager with <code>timeToLive</code> = 5 seconds.
-authenticationManager.<code>renew</code>(&quot;aaa&quot;, 1); // No token exists with tokenId &quot;aaa&quot; at time 1, so nothing happens.
-authenticationManager.generate(&quot;aaa&quot;, 2); // Generates a new token with tokenId &quot;aaa&quot; at time 2.
-authenticationManager.<code>countUnexpiredTokens</code>(6); // The token with tokenId &quot;aaa&quot; is the only unexpired one at time 6, so return 1.
-authenticationManager.generate(&quot;bbb&quot;, 7); // Generates a new token with tokenId &quot;bbb&quot; at time 7.
-authenticationManager.<code>renew</code>(&quot;aaa&quot;, 8); // The token with tokenId &quot;aaa&quot; expired at time 7, and 8 &gt;= 7, so at time 8 the <code>renew</code> request is ignored, and nothing happens.
-authenticationManager.<code>renew</code>(&quot;bbb&quot;, 10); // The token with tokenId &quot;bbb&quot; is unexpired at time 10, so the <code>renew</code> request is fulfilled and now the token will expire at time 15.
-authenticationManager.<code>countUnexpiredTokens</code>(15); // The token with tokenId &quot;bbb&quot; expires at time 15, and the token with tokenId &quot;aaa&quot; expired at time 7, so currently no token is unexpired, so return 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= timeToLive &lt;= 10<sup>8</sup></code></li>
-	<li><code>1 &lt;= currentTime &lt;= 10<sup>8</sup></code></li>
-	<li><code>1 &lt;= tokenId.length &lt;= 5</code></li>
-	<li><code>tokenId</code> consists only of lowercase letters.</li>
-	<li>All calls to <code>generate</code> will contain unique values of <code>tokenId</code>.</li>
-	<li>The values of <code>currentTime</code> across all the function calls will be <strong>strictly increasing</strong>.</li>
-	<li>At most <code>2000</code> calls will be made to all functions combined.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Using a map, track the expiry times of the tokens.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When generating a new token, add it to the map with its expiry time.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-When renewing a token, check if it's on the map and has not expired yet. If so, update its expiry time.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-To count unexpired tokens, iterate on the map and check for each token if it's not expired yet.
-</details>
diff --git a/problems/design-bitset/README.md b/problems/design-bitset/README.md
deleted file mode 100644
index 2cbd3a0ed..000000000
--- a/problems/design-bitset/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-value-of-the-rearranged-number "Smallest Value of the Rearranged Number")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-time-to-remove-all-cars-containing-illegal-goods "Minimum Time to Remove All Cars Containing Illegal Goods")
-
-## [2166. Design Bitset (Medium)](https://leetcode.com/problems/design-bitset "设计位集")
-
-<p>A <strong>Bitset</strong> is a data structure that compactly stores bits.</p>
-
-<p>Implement the <code>Bitset</code> class:</p>
-
-<ul>
-	<li><code>Bitset(int size)</code> Initializes the Bitset with <code>size</code> bits, all of which are <code>0</code>.</li>
-	<li><code>void fix(int idx)</code> Updates the value of the bit at the index <code>idx</code> to <code>1</code>. If the value was already <code>1</code>, no change occurs.</li>
-	<li><code>void unfix(int idx)</code> Updates the value of the bit at the index <code>idx</code> to <code>0</code>. If the value was already <code>0</code>, no change occurs.</li>
-	<li><code>void flip()</code> Flips the values of each bit in the Bitset. In other words, all bits with value <code>0</code> will now have value <code>1</code> and vice versa.</li>
-	<li><code>boolean all()</code> Checks if the value of <strong>each</strong> bit in the Bitset is <code>1</code>. Returns <code>true</code> if it satisfies the condition, <code>false</code> otherwise.</li>
-	<li><code>boolean one()</code> Checks if there is <strong>at least one</strong> bit in the Bitset with value <code>1</code>. Returns <code>true</code> if it satisfies the condition, <code>false</code> otherwise.</li>
-	<li><code>int count()</code> Returns the <strong>total number</strong> of bits in the Bitset which have value <code>1</code>.</li>
-	<li><code>String toString()</code> Returns the current composition of the Bitset. Note that in the resultant string, the character at the <code>i<sup>th</sup></code> index should coincide with the value at the <code>i<sup>th</sup></code> bit of the Bitset.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Bitset&quot;, &quot;fix&quot;, &quot;fix&quot;, &quot;flip&quot;, &quot;all&quot;, &quot;unfix&quot;, &quot;flip&quot;, &quot;one&quot;, &quot;unfix&quot;, &quot;count&quot;, &quot;toString&quot;]
-[[5], [3], [1], [], [], [0], [], [], [0], [], []]
-<strong>Output</strong>
-[null, null, null, null, false, null, null, true, null, 2, &quot;01010&quot;]
-
-<strong>Explanation</strong>
-Bitset bs = new Bitset(5); // bitset = &quot;00000&quot;.
-bs.fix(3);     // the value at idx = 3 is updated to 1, so bitset = &quot;00010&quot;.
-bs.fix(1);     // the value at idx = 1 is updated to 1, so bitset = &quot;01010&quot;. 
-bs.flip();     // the value of each bit is flipped, so bitset = &quot;10101&quot;. 
-bs.all();      // return False, as not all values of the bitset are 1.
-bs.unfix(0);   // the value at idx = 0 is updated to 0, so bitset = &quot;00101&quot;.
-bs.flip();     // the value of each bit is flipped, so bitset = &quot;11010&quot;. 
-bs.one();      // return True, as there is at least 1 index with value 1.
-bs.unfix(0);   // the value at idx = 0 is updated to 0, so bitset = &quot;01010&quot;.
-bs.count();    // return 2, as there are 2 bits with value 1.
-bs.toString(); // return &quot;01010&quot;, which is the composition of bitset.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= size &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= idx &lt;= size - 1</code></li>
-	<li>At most <code>10<sup>5</sup></code> calls will be made <strong>in total</strong> to <code>fix</code>, <code>unfix</code>, <code>flip</code>, <code>all</code>, <code>one</code>, <code>count</code>, and <code>toString</code>.</li>
-	<li>At least one call will be made to <code>all</code>, <code>one</code>, <code>count</code>, or <code>toString</code>.</li>
-	<li>At most <code>5</code> calls will be made to <code>toString</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that flipping a bit twice does nothing.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In order to determine the value of a bit, consider how you can efficiently count the number of flips made on the bit since its latest update.
-</details>
diff --git a/problems/design-bounded-blocking-queue/README.md b/problems/design-bounded-blocking-queue/README.md
deleted file mode 100644
index 70fd07167..000000000
--- a/problems/design-bounded-blocking-queue/README.md
+++ /dev/null
@@ -1,90 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../make-array-strictly-increasing "Make Array Strictly Increasing")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-balloons "Maximum Number of Balloons")
-
-## [1188. Design Bounded Blocking Queue (Medium)](https://leetcode.com/problems/design-bounded-blocking-queue "设计有限阻塞队列")
-
-<p>Implement a thread safe bounded&nbsp;blocking queue that has&nbsp;the following&nbsp;methods:</p>
-
-<ul>
-	<li><code>BoundedBlockingQueue(int capacity)</code> The constructor initializes the queue with a maximum <code>capacity</code>.</li>
-	<li><code>void enqueue(int element)</code> Adds an <code>element</code> to the front of the queue. If the queue is full, the calling thread is blocked until the queue is no longer full.</li>
-	<li><code>int dequeue()</code> Returns the element at the rear of the queue and removes it. If the queue is empty, the calling thread is blocked until the queue is no longer empty.</li>
-	<li><code>int size()</code>&nbsp;Returns the number of elements currently in the queue.</li>
-</ul>
-
-<p>Your implementation will be tested using multiple threads at the same time. Each thread will either be a producer thread that only makes calls to the&nbsp;<code>enqueue</code>&nbsp;method or a consumer thread that only makes calls to the&nbsp;<code>dequeue</code>&nbsp;method. The&nbsp;<code>size</code>&nbsp;method will be called after every test case.</p>
-
-<p>Please do not use built-in implementations of bounded&nbsp;blocking queue as this will not be accepted in an interview.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong>
-1
-1
-[&quot;BoundedBlockingQueue&quot;,&quot;enqueue&quot;,&quot;dequeue&quot;,&quot;dequeue&quot;,&quot;enqueue&quot;,&quot;enqueue&quot;,&quot;enqueue&quot;,&quot;enqueue&quot;,&quot;dequeue&quot;]
-[[2],[1],[],[],[0],[2],[3],[4],[]]
-
-<strong>Output:</strong>
-[1,0,2,2]
-
-<strong>Explanation:
-</strong>Number of producer threads = 1
-Number of consumer threads = 1
-
-BoundedBlockingQueue queue = new BoundedBlockingQueue(2);   // initialize the queue with capacity = 2.
-
-queue.enqueue(1);   // The producer thread enqueues 1 to the queue.
-queue.dequeue();    // The consumer thread calls dequeue and returns 1 from the queue.
-queue.dequeue();    // Since the queue is empty, the consumer thread is blocked.
-queue.enqueue(0);   // The producer thread enqueues 0 to the queue. The consumer thread is unblocked and returns 0 from the queue.
-queue.enqueue(2);   // The producer thread enqueues 2 to the queue.
-queue.enqueue(3);   // The producer thread enqueues 3 to the queue.
-queue.enqueue(4);   // The producer thread is blocked because the queue&#39;s capacity (2) is reached.
-queue.dequeue();    // The consumer thread returns 2 from the queue. The producer thread is unblocked and enqueues 4 to the queue.
-queue.size();       // 2 elements remaining in the queue. size() is always called at the end of each test case.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong>
-3
-4
-[&quot;BoundedBlockingQueue&quot;,&quot;enqueue&quot;,&quot;enqueue&quot;,&quot;enqueue&quot;,&quot;dequeue&quot;,&quot;dequeue&quot;,&quot;dequeue&quot;,&quot;enqueue&quot;]
-[[3],[1],[0],[2],[],[],[],[3]]
-
-<strong>Output:</strong>
-[1,0,2,1]
-
-<strong>Explanation:
-</strong>Number of producer threads = 3
-Number of consumer threads = 4
-
-BoundedBlockingQueue queue = new BoundedBlockingQueue(3);   // initialize the queue with capacity = 3.
-
-queue.enqueue(1);   // Producer thread P1 enqueues 1 to the queue.
-queue.enqueue(0);   // Producer thread P2 enqueues 0 to the queue.
-queue.enqueue(2);   // Producer thread P3 enqueues 2 to the queue.
-queue.dequeue();    // Consumer thread C1 calls dequeue.
-queue.dequeue();    // Consumer thread C2 calls dequeue.
-queue.dequeue();    // Consumer thread C3 calls dequeue.
-queue.enqueue(3);   // One of the producer threads enqueues 3 to the queue.
-queue.size();       // 1 element remaining in the queue.
-
-Since the number of threads for producer/consumer is greater than 1, we do not know how the threads will be scheduled in the operating system, even though the input seems to imply the ordering. Therefore, any of the output [1,0,2] or [1,2,0] or [0,1,2] or [0,2,1] or [2,0,1] or [2,1,0] will be accepted.</pre>
-
-### Related Topics
-  [[Concurrency](../../tag/concurrency/README.md)]
diff --git a/problems/design-browser-history/README.md b/problems/design-browser-history/README.md
deleted file mode 100644
index 54bb7bfee..000000000
--- a/problems/design-browser-history/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-k-strongest-values-in-an-array "The k Strongest Values in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../paint-house-iii "Paint House III")
-
-## [1472. Design Browser History (Medium)](https://leetcode.com/problems/design-browser-history "设计浏览器历史记录")
-
-<p>You have a <strong>browser</strong> of one tab where you start on the <code>homepage</code> and you can visit another <code>url</code>, get back in the history number of <code>steps</code> or move forward in the history number of <code>steps</code>.</p>
-
-<p>Implement the <code>BrowserHistory</code> class:</p>
-
-<ul>
-	<li><code>BrowserHistory(string homepage)</code> Initializes the object with the <code>homepage</code>&nbsp;of the browser.</li>
-	<li><code>void visit(string url)</code>&nbsp;Visits&nbsp;<code>url</code> from the current page. It clears up all the forward history.</li>
-	<li><code>string back(int steps)</code>&nbsp;Move <code>steps</code> back in history. If you can only return <code>x</code> steps in the history and <code>steps &gt; x</code>, you will&nbsp;return only <code>x</code> steps. Return the current <code>url</code>&nbsp;after moving back in history <strong>at most</strong> <code>steps</code>.</li>
-	<li><code>string forward(int steps)</code>&nbsp;Move <code>steps</code> forward in history. If you can only forward <code>x</code> steps in the history and <code>steps &gt; x</code>, you will&nbsp;forward only&nbsp;<code>x</code> steps. Return the current <code>url</code>&nbsp;after forwarding in history <strong>at most</strong> <code>steps</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example:</strong></p>
-
-<pre>
-<b>Input:</b>
-[&quot;BrowserHistory&quot;,&quot;visit&quot;,&quot;visit&quot;,&quot;visit&quot;,&quot;back&quot;,&quot;back&quot;,&quot;forward&quot;,&quot;visit&quot;,&quot;forward&quot;,&quot;back&quot;,&quot;back&quot;]
-[[&quot;leetcode.com&quot;],[&quot;google.com&quot;],[&quot;facebook.com&quot;],[&quot;youtube.com&quot;],[1],[1],[1],[&quot;linkedin.com&quot;],[2],[2],[7]]
-<b>Output:</b>
-[null,null,null,null,&quot;facebook.com&quot;,&quot;google.com&quot;,&quot;facebook.com&quot;,null,&quot;linkedin.com&quot;,&quot;google.com&quot;,&quot;leetcode.com&quot;]
-
-<b>Explanation:</b>
-BrowserHistory browserHistory = new BrowserHistory(&quot;leetcode.com&quot;);
-browserHistory.visit(&quot;google.com&quot;);       // You are in &quot;leetcode.com&quot;. Visit &quot;google.com&quot;
-browserHistory.visit(&quot;facebook.com&quot;);     // You are in &quot;google.com&quot;. Visit &quot;facebook.com&quot;
-browserHistory.visit(&quot;youtube.com&quot;);      // You are in &quot;facebook.com&quot;. Visit &quot;youtube.com&quot;
-browserHistory.back(1);                   // You are in &quot;youtube.com&quot;, move back to &quot;facebook.com&quot; return &quot;facebook.com&quot;
-browserHistory.back(1);                   // You are in &quot;facebook.com&quot;, move back to &quot;google.com&quot; return &quot;google.com&quot;
-browserHistory.forward(1);                // You are in &quot;google.com&quot;, move forward to &quot;facebook.com&quot; return &quot;facebook.com&quot;
-browserHistory.visit(&quot;linkedin.com&quot;);     // You are in &quot;facebook.com&quot;. Visit &quot;linkedin.com&quot;
-browserHistory.forward(2);                // You are in &quot;linkedin.com&quot;, you cannot move forward any steps.
-browserHistory.back(2);                   // You are in &quot;linkedin.com&quot;, move back two steps to &quot;facebook.com&quot; then to &quot;google.com&quot;. return &quot;google.com&quot;
-browserHistory.back(7);                   // You are in &quot;google.com&quot;, you can move back only one step to &quot;leetcode.com&quot;. return &quot;leetcode.com&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= homepage.length &lt;= 20</code></li>
-	<li><code>1 &lt;= url.length &lt;= 20</code></li>
-	<li><code>1 &lt;= steps &lt;= 100</code></li>
-	<li><code>homepage</code> and <code>url</code> consist of&nbsp; &#39;.&#39; or lower case English letters.</li>
-	<li>At most <code>5000</code>&nbsp;calls will be made to <code>visit</code>, <code>back</code>, and <code>forward</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Doubly-Linked List](../../tag/doubly-linked-list/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use two stack one for back history and one for forward history and simulate the functions.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you do faster by using different data structure ?
-</details>
diff --git a/problems/design-circular-deque/README.md b/problems/design-circular-deque/README.md
deleted file mode 100644
index 06669c2c1..000000000
--- a/problems/design-circular-deque/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../solve-the-equation "Solve the Equation")
-　　　　　　　　　　　　　　　　
-[Next >](../design-search-autocomplete-system "Design Search Autocomplete System")
-
-## [641. Design Circular Deque (Medium)](https://leetcode.com/problems/design-circular-deque "设计循环双端队列")
-
-<p>Design your implementation of the circular double-ended queue (deque).</p>
-
-<p>Implement the <code>MyCircularDeque</code> class:</p>
-
-<ul>
-	<li><code>MyCircularDeque(int k)</code> Initializes the deque with a maximum size of <code>k</code>.</li>
-	<li><code>boolean insertFront()</code> Adds an item at the front of Deque. Returns <code>true</code> if the operation is successful, or <code>false</code> otherwise.</li>
-	<li><code>boolean insertLast()</code> Adds an item at the rear of Deque. Returns <code>true</code> if the operation is successful, or <code>false</code> otherwise.</li>
-	<li><code>boolean deleteFront()</code> Deletes an item from the front of Deque. Returns <code>true</code> if the operation is successful, or <code>false</code> otherwise.</li>
-	<li><code>boolean deleteLast()</code> Deletes an item from the rear of Deque. Returns <code>true</code> if the operation is successful, or <code>false</code> otherwise.</li>
-	<li><code>int getFront()</code> Returns the front item from the Deque. Returns <code>-1</code> if the deque is empty.</li>
-	<li><code>int getRear()</code> Returns the last item from Deque. Returns <code>-1</code> if the deque is empty.</li>
-	<li><code>boolean isEmpty()</code> Returns <code>true</code> if the deque is empty, or <code>false</code> otherwise.</li>
-	<li><code>boolean isFull()</code> Returns <code>true</code> if the deque is full, or <code>false</code> otherwise.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyCircularDeque&quot;, &quot;insertLast&quot;, &quot;insertLast&quot;, &quot;insertFront&quot;, &quot;insertFront&quot;, &quot;getRear&quot;, &quot;isFull&quot;, &quot;deleteLast&quot;, &quot;insertFront&quot;, &quot;getFront&quot;]
-[[3], [1], [2], [3], [4], [], [], [], [4], []]
-<strong>Output</strong>
-[null, true, true, true, false, 2, true, true, true, 4]
-
-<strong>Explanation</strong>
-MyCircularDeque myCircularDeque = new MyCircularDeque(3);
-myCircularDeque.insertLast(1);  // return True
-myCircularDeque.insertLast(2);  // return True
-myCircularDeque.insertFront(3); // return True
-myCircularDeque.insertFront(4); // return False, the queue is full.
-myCircularDeque.getRear();      // return 2
-myCircularDeque.isFull();       // return True
-myCircularDeque.deleteLast();   // return True
-myCircularDeque.insertFront(4); // return True
-myCircularDeque.getFront();     // return 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= 1000</code></li>
-	<li><code>0 &lt;= value &lt;= 1000</code></li>
-	<li>At most <code>2000</code> calls will be made to <code>insertFront</code>, <code>insertLast</code>, <code>deleteFront</code>, <code>deleteLast</code>, <code>getFront</code>, <code>getRear</code>, <code>isEmpty</code>, <code>isFull</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Design Circular Queue](../design-circular-queue) (Medium)
diff --git a/problems/design-circular-deque/design_circular_deque.go b/problems/design-circular-deque/design_circular_deque.go
deleted file mode 100644
index 2714b6a68..000000000
--- a/problems/design-circular-deque/design_circular_deque.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem641
diff --git a/problems/design-circular-deque/design_circular_deque_test.go b/problems/design-circular-deque/design_circular_deque_test.go
deleted file mode 100644
index 2714b6a68..000000000
--- a/problems/design-circular-deque/design_circular_deque_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem641
diff --git a/problems/design-circular-queue/README.md b/problems/design-circular-queue/README.md
deleted file mode 100644
index ac1b86d00..000000000
--- a/problems/design-circular-queue/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../task-scheduler "Task Scheduler")
-　　　　　　　　　　　　　　　　
-[Next >](../add-one-row-to-tree "Add One Row to Tree")
-
-## [622. Design Circular Queue (Medium)](https://leetcode.com/problems/design-circular-queue "设计循环队列")
-
-<p>Design your implementation of the circular queue. The circular queue is a linear data structure in which the operations are performed based on FIFO (First In First Out) principle and the last position is connected back to the first position to make a circle. It is also called &quot;Ring Buffer&quot;.</p>
-
-<p>One of the benefits of the circular queue is that we can make use of the spaces in front of the queue. In a normal queue, once the queue becomes full, we cannot insert the next element even if there is a space in front of the queue. But using the circular queue, we can use the space to store new values.</p>
-
-<p>Implementation the <code>MyCircularQueue</code> class:</p>
-
-<ul>
-	<li><code>MyCircularQueue(k)</code> Initializes the object with the size of the queue to be <code>k</code>.</li>
-	<li><code>int Front()</code> Gets the front item from the queue. If the queue is empty, return <code>-1</code>.</li>
-	<li><code>int Rear()</code> Gets the last item from the queue. If the queue is empty, return <code>-1</code>.</li>
-	<li><code>boolean enQueue(int value)</code> Inserts an element into the circular queue. Return <code>true</code> if the operation is successful.</li>
-	<li><code>boolean deQueue()</code> Deletes an element from the circular queue. Return <code>true</code> if the operation is successful.</li>
-	<li><code>boolean isEmpty()</code> Checks whether the circular queue is empty or not.</li>
-	<li><code>boolean isFull()</code> Checks whether the circular queue is full or not.</li>
-</ul>
-
-<p>You must solve the problem without using the built-in queue data structure in your programming language.&nbsp;</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyCircularQueue&quot;, &quot;enQueue&quot;, &quot;enQueue&quot;, &quot;enQueue&quot;, &quot;enQueue&quot;, &quot;Rear&quot;, &quot;isFull&quot;, &quot;deQueue&quot;, &quot;enQueue&quot;, &quot;Rear&quot;]
-[[3], [1], [2], [3], [4], [], [], [], [4], []]
-<strong>Output</strong>
-[null, true, true, true, false, 3, true, true, true, 4]
-
-<strong>Explanation</strong>
-MyCircularQueue myCircularQueue = new MyCircularQueue(3);
-myCircularQueue.enQueue(1); // return True
-myCircularQueue.enQueue(2); // return True
-myCircularQueue.enQueue(3); // return True
-myCircularQueue.enQueue(4); // return False
-myCircularQueue.Rear();     // return 3
-myCircularQueue.isFull();   // return True
-myCircularQueue.deQueue();  // return True
-myCircularQueue.enQueue(4); // return True
-myCircularQueue.Rear();     // return 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= 1000</code></li>
-	<li><code>0 &lt;= value &lt;= 1000</code></li>
-	<li>At most <code>3000</code> calls will be made to&nbsp;<code>enQueue</code>, <code>deQueue</code>,&nbsp;<code>Front</code>,&nbsp;<code>Rear</code>,&nbsp;<code>isEmpty</code>, and&nbsp;<code>isFull</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Design Circular Deque](../design-circular-deque) (Medium)
diff --git a/problems/design-circular-queue/design_circular_queue.go b/problems/design-circular-queue/design_circular_queue.go
deleted file mode 100644
index 1d08ba32a..000000000
--- a/problems/design-circular-queue/design_circular_queue.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem622
diff --git a/problems/design-circular-queue/design_circular_queue_test.go b/problems/design-circular-queue/design_circular_queue_test.go
deleted file mode 100644
index 1d08ba32a..000000000
--- a/problems/design-circular-queue/design_circular_queue_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem622
diff --git a/problems/design-compressed-string-iterator/README.md b/problems/design-compressed-string-iterator/README.md
deleted file mode 100644
index d6072bc36..000000000
--- a/problems/design-compressed-string-iterator/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../consecutive-available-seats "Consecutive Available Seats")
-　　　　　　　　　　　　　　　　
-[Next >](../can-place-flowers "Can Place Flowers")
-
-## [604. Design Compressed String Iterator (Easy)](https://leetcode.com/problems/design-compressed-string-iterator "迭代压缩字符串")
-
-<p>
-Design and implement a data structure for a compressed string iterator. It should support the following operations: <code>next</code> and <code>hasNext</code>.
-</p>
-
-<p>
-The given compressed string will be in the form of each letter followed by a positive integer representing the number of this letter existing in the original uncompressed string.
-</p>
-
-<p>
-<code>next()</code> - if the original string still has uncompressed characters, return the next letter; Otherwise return a white space.<br>
-<code>hasNext()</code> - Judge whether there is any letter needs to be uncompressed.
-</p>
-
-<p>
-<b>Note:</b><br />
-Please remember to <b>RESET</b> your class variables declared in StringIterator, as static/class variables are <b>persisted across multiple test cases</b>. Please see <a href="https://leetcode.com/faq/#different-output">here</a> for more details.
-</p>
-
-
-<p><b>Example:</b>
-<pre>
-StringIterator iterator = new StringIterator("L1e2t1C1o1d1e1");
-
-iterator.next(); // return 'L'
-iterator.next(); // return 'e'
-iterator.next(); // return 'e'
-iterator.next(); // return 't'
-iterator.next(); // return 'C'
-iterator.next(); // return 'o'
-iterator.next(); // return 'd'
-iterator.hasNext(); // return true
-iterator.next(); // return 'e'
-iterator.hasNext(); // return false
-iterator.next(); // return ' '
-</pre>
-</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Iterator](../../tag/iterator/README.md)]
-
-### Similar Questions
-  1. [LRU Cache](../lru-cache) (Medium)
-  1. [String Compression](../string-compression) (Medium)
diff --git a/problems/design-compressed-string-iterator/design_compressed_string_iterator.go b/problems/design-compressed-string-iterator/design_compressed_string_iterator.go
deleted file mode 100644
index 0b1c1c5ff..000000000
--- a/problems/design-compressed-string-iterator/design_compressed_string_iterator.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem604
diff --git a/problems/design-compressed-string-iterator/design_compressed_string_iterator_test.go b/problems/design-compressed-string-iterator/design_compressed_string_iterator_test.go
deleted file mode 100644
index 0b1c1c5ff..000000000
--- a/problems/design-compressed-string-iterator/design_compressed_string_iterator_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem604
diff --git a/problems/design-excel-sum-formula/README.md b/problems/design-excel-sum-formula/README.md
deleted file mode 100644
index 367ed9cca..000000000
--- a/problems/design-excel-sum-formula/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../course-schedule-iii "Course Schedule III")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-range-covering-elements-from-k-lists "Smallest Range Covering Elements from K Lists")
-
-## [631. Design Excel Sum Formula (Hard)](https://leetcode.com/problems/design-excel-sum-formula "设计 Excel 求和公式")
-
-<p>Your task is to design the basic function of Excel and implement the function of sum formula.  Specifically, you need to implement the following functions:</p>
-
-
-
-<p><code>Excel(int H, char W):</code> This is the constructor. The inputs represents the height and width of the Excel form. <b>H</b> is a positive integer, range from 1 to 26. It represents the height. <b>W</b> is a character range from 'A' to 'Z'. It represents that the width is the number of characters from 'A' to <b>W</b>. The Excel form content is represented by a height * width 2D integer array <code>C</code>, it should be initialized to zero. You should assume that the first row of <code>C</code> starts from 1, and the first column of <code>C</code> starts from 'A'.</p>
-
-<br>
-
-<p><code>void Set(int row, char column, int val):</code> Change the value at <code>C(row, column)</code> to be val.</p>
-<br>
-<p><code>int Get(int row, char column):</code> Return the value at <code>C(row, column)</code>.</p>
-<br>
-<p><code>int Sum(int row, char column, List of Strings : numbers):</code> This function calculate and set the value at <code>C(row, column)</code>, where the value should be the sum of cells represented by <code>numbers</code>. This function return the sum result at <code>C(row, column)</code>. This sum formula should exist until this cell is overlapped by another value or another sum formula.</p>
-
-<p><code>numbers</code> is a list of strings that each string represent a cell or a range of cells. If the string represent a single cell, then it has the following format : <code>ColRow</code>. For example, "F7" represents the cell at (7, F). </p>
-
-<p>If the string represent a range of cells, then it has the following format : <code>ColRow1:ColRow2</code>. The range will always be a rectangle, and ColRow1 represent the position of the top-left cell, and ColRow2 represents the position of the bottom-right cell. </p>
-<br>
-<p><b>Example 1:</b><br />
-<pre>
-Excel(3,"C"); 
-// construct a 3*3 2D array with all zero.
-//   A B C
-// 1 0 0 0
-// 2 0 0 0
-// 3 0 0 0
-
-Set(1, "A", 2);
-// set C(1,"A") to be 2.
-//   A B C
-// 1 2 0 0
-// 2 0 0 0
-// 3 0 0 0
-
-Sum(3, "C", ["A1", "A1:B2"]);
-// set C(3,"C") to be the sum of value at C(1,"A") and the values sum of the rectangle range whose top-left cell is C(1,"A") and bottom-right cell is C(2,"B"). Return 4. 
-//   A B C
-// 1 2 0 0
-// 2 0 0 0
-// 3 0 0 4
-
-Set(2, "B", 2);
-// set C(2,"B") to be 2. Note C(3, "C") should also be changed.
-//   A B C
-// 1 2 0 0
-// 2 0 2 0
-// 3 0 0 6
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>You could assume that there won't be any circular sum reference. For example, A1 = sum(B1) and B1 = sum(A1).</li>
-<li> The test cases are using double-quotes to represent a character.</li>
-<li>Please remember to <b>RESET</b> your class variables declared in class Excel, as static/class variables are <b>persisted across multiple test cases</b>. Please see <a href="https://leetcode.com/faq/#different-output">here</a> for more details.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
diff --git a/problems/design-excel-sum-formula/design_excel_sum_formula.go b/problems/design-excel-sum-formula/design_excel_sum_formula.go
deleted file mode 100644
index 6743bf349..000000000
--- a/problems/design-excel-sum-formula/design_excel_sum_formula.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem631
diff --git a/problems/design-excel-sum-formula/design_excel_sum_formula_test.go b/problems/design-excel-sum-formula/design_excel_sum_formula_test.go
deleted file mode 100644
index 6743bf349..000000000
--- a/problems/design-excel-sum-formula/design_excel_sum_formula_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem631
diff --git a/problems/design-file-system/README.md b/problems/design-file-system/README.md
deleted file mode 100644
index c37500d85..000000000
--- a/problems/design-file-system/README.md
+++ /dev/null
@@ -1,92 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../single-row-keyboard "Single-Row Keyboard")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-connect-sticks "Minimum Cost to Connect Sticks")
-
-## [1166. Design File System (Medium)](https://leetcode.com/problems/design-file-system "设计文件系统")
-
-<p>You are asked to design a file system&nbsp;which provides two functions:</p>
-
-<ul>
-	<li><strong>createPath(path, value):</strong>&nbsp;Creates a new path and associates a value to it if possible and returns <code>True</code>.&nbsp;Returns <code>False</code>&nbsp;if the path already exists or its parent path doesn&#39;t exist.</li>
-	<li><strong>get(path):</strong>&nbsp;Returns the value associated with a path or returns&nbsp;<code>-1</code>&nbsp;if the path doesn&#39;t exist.</li>
-</ul>
-
-<p>The format of a path is&nbsp;one or more concatenated strings of the form:&nbsp;<code>/</code> followed by one or more lowercase English letters. For example, <code>/leetcode</code>&nbsp;and <code>/leetcode/problems</code>&nbsp;are valid paths while an empty string and <code>/</code>&nbsp;are not.</p>
-
-<p>Implement the two functions.</p>
-
-<p>Please refer to the examples for clarifications.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-[&quot;FileSystem&quot;,&quot;createPath&quot;,&quot;get&quot;]
-[[],[&quot;/a&quot;,1],[&quot;/a&quot;]]
-<strong>Output:</strong> 
-[null,true,1]
-<strong>Explanation:</strong> 
-FileSystem fileSystem = new FileSystem();
-
-fileSystem.createPath(&quot;/a&quot;, 1); // return true
-fileSystem.get(&quot;/a&quot;); // return 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-[&quot;FileSystem&quot;,&quot;createPath&quot;,&quot;createPath&quot;,&quot;get&quot;,&quot;createPath&quot;,&quot;get&quot;]
-[[],[&quot;/leet&quot;,1],[&quot;/leet/code&quot;,2],[&quot;/leet/code&quot;],[&quot;/c/d&quot;,1],[&quot;/c&quot;]]
-<strong>Output:</strong> 
-[null,true,true,2,false,-1]
-<strong>Explanation:</strong> 
-FileSystem fileSystem = new FileSystem();
-
-fileSystem.createPath(&quot;/leet&quot;, 1); // return true
-fileSystem.createPath(&quot;/leet/code&quot;, 2); // return true
-fileSystem.get(&quot;/leet/code&quot;); // return 2
-fileSystem.createPath(&quot;/c/d&quot;, 1); // return false because the parent path &quot;/c&quot; doesn&#39;t exist.
-fileSystem.get(&quot;/c&quot;); // return -1 because this path doesn&#39;t exist.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of&nbsp;calls to the two functions&nbsp;is less than or equal to <code>10^4</code> in total.</li>
-	<li><code>2 &lt;= path.length &lt;= 100</code></li>
-	<li><code>1 &lt;= value &lt;= 10^9</code></li>
-</ul>
-
-<p><strong>NOTE:</strong>&nbsp;create method has been changed on August&nbsp;29, 2019 to createPath. Please reset to default code definition to get new method signature.</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if you think of a tree hierarchy for the files?.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-A path is a node in the tree.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use a hash table to store the valid paths along with their values.
-</details>
diff --git a/problems/design-front-middle-back-queue/README.md b/problems/design-front-middle-back-queue/README.md
deleted file mode 100644
index 2d57da3a1..000000000
--- a/problems/design-front-middle-back-queue/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../merge-in-between-linked-lists "Merge In Between Linked Lists")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-removals-to-make-mountain-array "Minimum Number of Removals to Make Mountain Array")
-
-## [1670. Design Front Middle Back Queue (Medium)](https://leetcode.com/problems/design-front-middle-back-queue "设计前中后队列")
-
-<p>Design a queue that supports <code>push</code> and <code>pop</code> operations in the front, middle, and back.</p>
-
-<p>Implement the <code>FrontMiddleBack</code> class:</p>
-
-<ul>
-	<li><code>FrontMiddleBack()</code> Initializes the queue.</li>
-	<li><code>void pushFront(int val)</code> Adds <code>val</code> to the <strong>front</strong> of the queue.</li>
-	<li><code>void pushMiddle(int val)</code> Adds <code>val</code> to the <strong>middle</strong> of the queue.</li>
-	<li><code>void pushBack(int val)</code> Adds <code>val</code> to the <strong>back</strong> of the queue.</li>
-	<li><code>int popFront()</code> Removes the <strong>front</strong> element of the queue and returns it. If the queue is empty, return <code>-1</code>.</li>
-	<li><code>int popMiddle()</code> Removes the <strong>middle</strong> element of the queue and returns it. If the queue is empty, return <code>-1</code>.</li>
-	<li><code>int popBack()</code> Removes the <strong>back</strong> element of the queue and returns it. If the queue is empty, return <code>-1</code>.</li>
-</ul>
-
-<p><strong>Notice</strong> that when there are <b>two</b> middle position choices, the operation is performed on the <strong>frontmost</strong> middle position choice. For example:</p>
-
-<ul>
-	<li>Pushing <code>6</code> into the middle of <code>[1, 2, 3, 4, 5]</code> results in <code>[1, 2, <u>6</u>, 3, 4, 5]</code>.</li>
-	<li>Popping the middle from <code>[1, 2, <u>3</u>, 4, 5, 6]</code> returns <code>3</code> and results in <code>[1, 2, 4, 5, 6]</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong>
-[&quot;FrontMiddleBackQueue&quot;, &quot;pushFront&quot;, &quot;pushBack&quot;, &quot;pushMiddle&quot;, &quot;pushMiddle&quot;, &quot;popFront&quot;, &quot;popMiddle&quot;, &quot;popMiddle&quot;, &quot;popBack&quot;, &quot;popFront&quot;]
-[[], [1], [2], [3], [4], [], [], [], [], []]
-<strong>Output:</strong>
-[null, null, null, null, null, 1, 3, 4, 2, -1]
-
-<strong>Explanation:</strong>
-FrontMiddleBackQueue q = new FrontMiddleBackQueue();
-q.pushFront(1);   // [<u>1</u>]
-q.pushBack(2);    // [1, <u>2</u>]
-q.pushMiddle(3);  // [1, <u>3</u>, 2]
-q.pushMiddle(4);  // [1, <u>4</u>, 3, 2]
-q.popFront();     // return 1 -&gt; [4, 3, 2]
-q.popMiddle();    // return 3 -&gt; [4, 2]
-q.popMiddle();    // return 4 -&gt; [2]
-q.popBack();      // return 2 -&gt; []
-q.popFront();     // return -1 -&gt; [] (The queue is empty)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= val &lt;= 10<sup>9</sup></code></li>
-	<li>At most&nbsp;<code>1000</code>&nbsp;calls will be made to&nbsp;<code>pushFront</code>,&nbsp;<code>pushMiddle</code>,&nbsp;<code>pushBack</code>, <code>popFront</code>, <code>popMiddle</code>, and <code>popBack</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The constraints are low enough for a brute force, single array approach.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For an O(1) per method approach, use 2 double-ended queues: one for the first half and one for the second half.
-</details>
diff --git a/problems/design-hashmap/README.md b/problems/design-hashmap/README.md
deleted file mode 100644
index ede07f6c4..000000000
--- a/problems/design-hashmap/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-hashset "Design HashSet")
-　　　　　　　　　　　　　　　　
-[Next >](../design-linked-list "Design Linked List")
-
-## [706. Design HashMap (Easy)](https://leetcode.com/problems/design-hashmap "设计哈希映射")
-
-<p>Design a HashMap without using any built-in hash table libraries.</p>
-
-<p>Implement the <code>MyHashMap</code> class:</p>
-
-<ul>
-	<li><code>MyHashMap()</code> initializes the object with an empty map.</li>
-	<li><code>void put(int key, int value)</code> inserts a <code>(key, value)</code> pair into the HashMap. If the <code>key</code> already exists in the map, update the corresponding <code>value</code>.</li>
-	<li><code>int get(int key)</code> returns the <code>value</code> to which the specified <code>key</code> is mapped, or <code>-1</code> if this map contains no mapping for the <code>key</code>.</li>
-	<li><code>void remove(key)</code> removes the <code>key</code> and its corresponding <code>value</code> if the map contains the mapping for the <code>key</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyHashMap&quot;, &quot;put&quot;, &quot;put&quot;, &quot;get&quot;, &quot;get&quot;, &quot;put&quot;, &quot;get&quot;, &quot;remove&quot;, &quot;get&quot;]
-[[], [1, 1], [2, 2], [1], [3], [2, 1], [2], [2], [2]]
-<strong>Output</strong>
-[null, null, null, 1, -1, null, 1, null, -1]
-
-<strong>Explanation</strong>
-MyHashMap myHashMap = new MyHashMap();
-myHashMap.put(1, 1); // The map is now [[1,1]]
-myHashMap.put(2, 2); // The map is now [[1,1], [2,2]]
-myHashMap.get(1);    // return 1, The map is now [[1,1], [2,2]]
-myHashMap.get(3);    // return -1 (i.e., not found), The map is now [[1,1], [2,2]]
-myHashMap.put(2, 1); // The map is now [[1,1], [2,1]] (i.e., update the existing value)
-myHashMap.get(2);    // return 1, The map is now [[1,1], [2,1]]
-myHashMap.remove(2); // remove the mapping for 2, The map is now [[1,1]]
-myHashMap.get(2);    // return -1 (i.e., not found), The map is now [[1,1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= key, value &lt;= 10<sup>6</sup></code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>put</code>, <code>get</code>, and <code>remove</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Similar Questions
-  1. [Design HashSet](../design-hashset) (Easy)
-  1. [Design Skiplist](../design-skiplist) (Hard)
diff --git a/problems/design-hashmap/design_hashmap.go b/problems/design-hashmap/design_hashmap.go
deleted file mode 100644
index 1cdfb05aa..000000000
--- a/problems/design-hashmap/design_hashmap.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package problem706
-
-type MyHashMap struct {
-	data map[int]int
-}
-
-/** Initialize your data structure here. */
-func Constructor() MyHashMap {
-	return MyHashMap{make(map[int]int, 0)}
-}
-
-/** value will always be non-negative. */
-func (this *MyHashMap) Put(key int, value int) {
-	this.data[key] = value
-}
-
-/** Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key */
-func (this *MyHashMap) Get(key int) int {
-	if v, ok := this.data[key]; ok {
-		return v
-	}
-	return -1
-}
-
-/** Removes the mapping of the specified value key if this map contains a mapping for the key */
-func (this *MyHashMap) Remove(key int) {
-	delete(this.data, key)
-}
-
-/**
- * Your MyHashMap object will be instantiated and called as such:
- * obj := Constructor();
- * obj.Put(key,value);
- * param_2 := obj.Get(key);
- * obj.Remove(key);
- */
diff --git a/problems/design-hashmap/design_hashmap_test.go b/problems/design-hashmap/design_hashmap_test.go
deleted file mode 100644
index 5f4ed59d0..000000000
--- a/problems/design-hashmap/design_hashmap_test.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem706
-
-import "testing"
-
-func TestDesignHashmap(t *testing.T) {
-	obj := Constructor()
-	obj.Put(1, 1)
-	obj.Put(2, 2)
-	got := obj.Get(1) == 1
-	got = obj.Get(3) == -1 && got
-	obj.Put(2, 1)
-	got = obj.Get(2) == 1 && got
-	obj.Remove(2)
-	got = obj.Get(2) == -1 && got
-	if !got {
-		t.Fatalf("got: %v, want: %v", got, true)
-	}
-}
diff --git a/problems/design-hashset/README.md b/problems/design-hashset/README.md
deleted file mode 100644
index bd2bd2926..000000000
--- a/problems/design-hashset/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-search "Binary Search")
-　　　　　　　　　　　　　　　　
-[Next >](../design-hashmap "Design HashMap")
-
-## [705. Design HashSet (Easy)](https://leetcode.com/problems/design-hashset "设计哈希集合")
-
-<p>Design a HashSet without using any built-in hash table libraries.</p>
-
-<p>Implement <code>MyHashSet</code> class:</p>
-
-<ul>
-	<li><code>void add(key)</code> Inserts the value <code>key</code> into the HashSet.</li>
-	<li><code>bool contains(key)</code> Returns whether the value <code>key</code> exists in the HashSet or not.</li>
-	<li><code>void remove(key)</code> Removes the value <code>key</code> in the HashSet. If <code>key</code> does not exist in the HashSet, do nothing.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyHashSet&quot;, &quot;add&quot;, &quot;add&quot;, &quot;contains&quot;, &quot;contains&quot;, &quot;add&quot;, &quot;contains&quot;, &quot;remove&quot;, &quot;contains&quot;]
-[[], [1], [2], [1], [3], [2], [2], [2], [2]]
-<strong>Output</strong>
-[null, null, null, true, false, null, true, null, false]
-
-<strong>Explanation</strong>
-MyHashSet myHashSet = new MyHashSet();
-myHashSet.add(1);      // set = [1]
-myHashSet.add(2);      // set = [1, 2]
-myHashSet.contains(1); // return True
-myHashSet.contains(3); // return False, (not found)
-myHashSet.add(2);      // set = [1, 2]
-myHashSet.contains(2); // return True
-myHashSet.remove(2);   // set = [1]
-myHashSet.contains(2); // return False, (already removed)</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= key &lt;= 10<sup>6</sup></code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>add</code>, <code>remove</code>, and <code>contains</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Similar Questions
-  1. [Design HashMap](../design-hashmap) (Easy)
diff --git a/problems/design-hashset/design_hashset.go b/problems/design-hashset/design_hashset.go
deleted file mode 100644
index 789bdcc86..000000000
--- a/problems/design-hashset/design_hashset.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem705
-
-type MyHashSet struct {
-	data map[int]bool
-}
-
-/** Initialize your data structure here. */
-func Constructor() MyHashSet {
-	return MyHashSet{make(map[int]bool, 0)}
-}
-
-func (this *MyHashSet) Add(key int) {
-	this.data[key] = true
-}
-
-func (this *MyHashSet) Remove(key int) {
-	delete(this.data, key)
-}
-
-/** Returns true if this set contains the specified element */
-func (this *MyHashSet) Contains(key int) bool {
-	return this.data[key]
-}
-
-/**
- * Your MyHashSet object will be instantiated and called as such:
- * obj := Constructor();
- * obj.Add(key);
- * obj.Remove(key);
- * param_3 := obj.Contains(key);
- */
diff --git a/problems/design-hashset/design_hashset_test.go b/problems/design-hashset/design_hashset_test.go
deleted file mode 100644
index 8bb60f2ee..000000000
--- a/problems/design-hashset/design_hashset_test.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem705
-
-import "testing"
-
-func TestDesignHashset(t *testing.T) {
-	obj := Constructor()
-	obj.Add(1)
-	obj.Add(2)
-	got := obj.Contains(1)
-	got = !obj.Contains(3) && got
-	obj.Add(2)
-	got = obj.Contains(2) && got
-	obj.Remove(2)
-	got = !obj.Contains(2) && got
-	if !got {
-		t.Fatalf("got: %v, want: %v", got, true)
-	}
-}
diff --git a/problems/design-hit-counter/README.md b/problems/design-hit-counter/README.md
deleted file mode 100644
index e094f0392..000000000
--- a/problems/design-hit-counter/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bomb-enemy "Bomb Enemy")
-　　　　　　　　　　　　　　　　
-[Next >](../max-sum-of-rectangle-no-larger-than-k "Max Sum of Rectangle No Larger Than K")
-
-## [362. Design Hit Counter (Medium)](https://leetcode.com/problems/design-hit-counter "敲击计数器")
-
-<p>Design a hit counter which counts the number of hits received in the past 5 minutes.</p>
-
-<p>Each function accepts a timestamp parameter (in seconds granularity) and you may assume that calls are being made to the system in chronological order (ie, the timestamp is monotonically increasing). You may assume that the earliest timestamp starts at 1.</p>
-
-<p>It is possible that several hits arrive roughly at the same time.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-HitCounter counter = new HitCounter();
-
-// hit at timestamp 1.
-counter.hit(1);
-
-// hit at timestamp 2.
-counter.hit(2);
-
-// hit at timestamp 3.
-counter.hit(3);
-
-// get hits at timestamp 4, should return 3.
-counter.getHits(4);
-
-// hit at timestamp 300.
-counter.hit(300);
-
-// get hits at timestamp 300, should return 4.
-counter.getHits(300);
-
-// get hits at timestamp 301, should return 3.
-counter.getHits(301); 
-</pre>
-
-<p><b>Follow up:</b><br />
-What if the number of hits per second could be very large? Does your design scale?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-
-### Similar Questions
-  1. [Logger Rate Limiter](../logger-rate-limiter) (Easy)
diff --git a/problems/design-hit-counter/design_hit_counter.go b/problems/design-hit-counter/design_hit_counter.go
deleted file mode 100644
index 590576ab8..000000000
--- a/problems/design-hit-counter/design_hit_counter.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem362
diff --git a/problems/design-hit-counter/design_hit_counter_test.go b/problems/design-hit-counter/design_hit_counter_test.go
deleted file mode 100644
index 590576ab8..000000000
--- a/problems/design-hit-counter/design_hit_counter_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem362
diff --git a/problems/design-in-memory-file-system/README.md b/problems/design-in-memory-file-system/README.md
deleted file mode 100644
index 4c8354284..000000000
--- a/problems/design-in-memory-file-system/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../erect-the-fence "Erect the Fence")
-　　　　　　　　　　　　　　　　
-[Next >](../n-ary-tree-preorder-traversal "N-ary Tree Preorder Traversal")
-
-## [588. Design In-Memory File System (Hard)](https://leetcode.com/problems/design-in-memory-file-system "设计内存文件系统")
-
-<p>Design an in-memory file system to simulate the following functions:</p>
-
-<p><code>ls</code>: Given a path in string format. If it is a file path, return a list that only contains this file&#39;s name. If it is a directory path, return the list of file and directory names <b>in this directory</b>. Your output (file and directory names together) should in <b>lexicographic order</b>.</p>
-
-<p><code>mkdir</code>: Given a <b>directory path</b> that does not exist, you should make a new directory according to the path. If the middle directories in the path don&#39;t exist either, you should create them as well. This function has void return type.</p>
-
-<p><code>addContentToFile</code>: Given a <b>file path</b> and <b>file content</b> in string format. If the file doesn&#39;t exist, you need to create that file containing given content. If the file already exists, you need to <b>append</b> given content to original content. This function has void return type.</p>
-
-<p><code>readContentFromFile</code>: Given a <b>file path</b>, return its <b>content</b> in string format.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Example:</b></p>
-
-<pre><b>Input:</b> 
-[&quot;FileSystem&quot;,&quot;ls&quot;,&quot;mkdir&quot;,&quot;addContentToFile&quot;,&quot;ls&quot;,&quot;readContentFromFile&quot;]
-[[],[&quot;/&quot;],[&quot;/a/b/c&quot;],[&quot;/a/b/c/d&quot;,&quot;hello&quot;],[&quot;/&quot;],[&quot;/a/b/c/d&quot;]]
-
-<b>Output:</b>
-[null,[],null,null,[&quot;a&quot;],&quot;hello&quot;]
-
-<b>Explanation:</b>
-<img alt="filesystem" src="https://assets.leetcode.com/uploads/2018/10/12/filesystem.png" style="width: 640px;" />
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>You can assume all file or directory paths are absolute paths which begin with <code>/</code> and do not end with <code>/</code> except that the path is just <code>&quot;/&quot;</code>.</li>
-	<li>You can assume that all operations will be passed valid parameters and users will not attempt to retrieve file content or list a directory or file that does not exist.</li>
-	<li>You can assume that all directory names and file names only contain lower-case letters, and same names won&#39;t exist in the same directory.</li>
-</ol>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [LRU Cache](../lru-cache) (Medium)
-  1. [LFU Cache](../lfu-cache) (Hard)
-  1. [Design Log Storage System](../design-log-storage-system) (Medium)
diff --git a/problems/design-in-memory-file-system/design_in_memory_file_system.go b/problems/design-in-memory-file-system/design_in_memory_file_system.go
deleted file mode 100644
index fe1e82cbb..000000000
--- a/problems/design-in-memory-file-system/design_in_memory_file_system.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem588
diff --git a/problems/design-in-memory-file-system/design_in_memory_file_system_test.go b/problems/design-in-memory-file-system/design_in_memory_file_system_test.go
deleted file mode 100644
index fe1e82cbb..000000000
--- a/problems/design-in-memory-file-system/design_in_memory_file_system_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem588
diff --git a/problems/design-linked-list/README.md b/problems/design-linked-list/README.md
deleted file mode 100644
index 573e5df43..000000000
--- a/problems/design-linked-list/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-hashmap "Design HashMap")
-　　　　　　　　　　　　　　　　
-[Next >](../insert-into-a-sorted-circular-linked-list "Insert into a Sorted Circular Linked List")
-
-## [707. Design Linked List (Medium)](https://leetcode.com/problems/design-linked-list "设计链表")
-
-<p>Design your implementation of the linked list. You can choose to use a singly or doubly linked list.<br />
-A node in a singly linked list should have two attributes: <code>val</code> and <code>next</code>. <code>val</code> is the value of the current node, and <code>next</code> is a pointer/reference to the next node.<br />
-If you want to use the doubly linked list, you will need one more attribute <code>prev</code> to indicate the previous node in the linked list. Assume all nodes in the linked list are <strong>0-indexed</strong>.</p>
-
-<p>Implement the <code>MyLinkedList</code> class:</p>
-
-<ul>
-	<li><code>MyLinkedList()</code> Initializes the <code>MyLinkedList</code> object.</li>
-	<li><code>int get(int index)</code> Get the value of the <code>index<sup>th</sup></code> node in the linked list. If the index is invalid, return <code>-1</code>.</li>
-	<li><code>void addAtHead(int val)</code> Add a node of value <code>val</code> before the first element of the linked list. After the insertion, the new node will be the first node of the linked list.</li>
-	<li><code>void addAtTail(int val)</code> Append a node of value <code>val</code> as the last element of the linked list.</li>
-	<li><code>void addAtIndex(int index, int val)</code> Add a node of value <code>val</code> before the <code>index<sup>th</sup></code> node in the linked list. If <code>index</code> equals the length of the linked list, the node will be appended to the end of the linked list. If <code>index</code> is greater than the length, the node <strong>will not be inserted</strong>.</li>
-	<li><code>void deleteAtIndex(int index)</code> Delete the <code>index<sup>th</sup></code> node in the linked list, if the index is valid.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyLinkedList&quot;, &quot;addAtHead&quot;, &quot;addAtTail&quot;, &quot;addAtIndex&quot;, &quot;get&quot;, &quot;deleteAtIndex&quot;, &quot;get&quot;]
-[[], [1], [3], [1, 2], [1], [1], [1]]
-<strong>Output</strong>
-[null, null, null, null, 2, null, 3]
-
-<strong>Explanation</strong>
-MyLinkedList myLinkedList = new MyLinkedList();
-myLinkedList.addAtHead(1);
-myLinkedList.addAtTail(3);
-myLinkedList.addAtIndex(1, 2);    // linked list becomes 1-&gt;2-&gt;3
-myLinkedList.get(1);              // return 2
-myLinkedList.deleteAtIndex(1);    // now the linked list is 1-&gt;3
-myLinkedList.get(1);              // return 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= index, val &lt;= 1000</code></li>
-	<li>Please do not use the built-in LinkedList library.</li>
-	<li>At most <code>2000</code> calls will be made to <code>get</code>, <code>addAtHead</code>, <code>addAtTail</code>, <code>addAtIndex</code> and <code>deleteAtIndex</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
diff --git a/problems/design-linked-list/design_linked_list.go b/problems/design-linked-list/design_linked_list.go
deleted file mode 100644
index da4e41c76..000000000
--- a/problems/design-linked-list/design_linked_list.go
+++ /dev/null
@@ -1,68 +0,0 @@
-package problem707
-
-import "container/list"
-
-type MyLinkedList struct {
-	data *list.List
-}
-
-/** Initialize your data structure here. */
-func Constructor() MyLinkedList {
-	return MyLinkedList{list.New()}
-}
-
-/** Get the value of the index-th node in the linked list. If the index is invalid, return -1. */
-func (this *MyLinkedList) Get(index int) int {
-	if index < 0 || index >= this.data.Len() {
-		return -1
-	}
-	node := this.data.Front()
-	for i := 0; i < index; i++ {
-		node = node.Next()
-	}
-	return node.Value.(int)
-}
-
-/** Add a node of value val before the first element of the linked list. After the insertion, the new node will be the first node of the linked list. */
-func (this *MyLinkedList) AddAtHead(val int) {
-	this.data.PushFront(val)
-}
-
-/** Append a node of value val to the last element of the linked list. */
-func (this *MyLinkedList) AddAtTail(val int) {
-	this.data.PushBack(val)
-}
-
-/** Add a node of value val before the index-th node in the linked list. If index equals to the length of linked list, the node will be appended to the end of linked list. If index is greater than the length, the node will not be inserted. */
-func (this *MyLinkedList) AddAtIndex(index int, val int) {
-	if index == this.data.Len() {
-		this.AddAtTail(val)
-	} else if index >= 0 && index < this.data.Len() {
-		node := this.data.Front()
-		for i := 0; i < index; i++ {
-			node = node.Next()
-		}
-		this.data.InsertBefore(val, node)
-	}
-}
-
-/** Delete the index-th node in the linked list, if the index is valid. */
-func (this *MyLinkedList) DeleteAtIndex(index int) {
-	if index >= 0 && index < this.data.Len() {
-		node := this.data.Front()
-		for i := 0; i < index; i++ {
-			node = node.Next()
-		}
-		this.data.Remove(node)
-	}
-}
-
-/**
- * Your MyLinkedList object will be instantiated and called as such:
- * obj := Constructor();
- * param_1 := obj.Get(index);
- * obj.AddAtHead(val);
- * obj.AddAtTail(val);
- * obj.AddAtIndex(index,val);
- * obj.DeleteAtIndex(index);
- */
diff --git a/problems/design-linked-list/design_linked_list_test.go b/problems/design-linked-list/design_linked_list_test.go
deleted file mode 100644
index bfcad69fb..000000000
--- a/problems/design-linked-list/design_linked_list_test.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem707
-
-import "testing"
-
-func TestConstructor(t *testing.T) {
-	obj := Constructor()
-	obj.AddAtHead(1)
-	obj.AddAtTail(3)
-	obj.AddAtIndex(1, 2)   // linked list becomes 1->2->3
-	got := obj.Get(1) == 2 // returns 2
-	obj.DeleteAtIndex(1)   // now the linked list is 1->3
-	got = obj.Get(1) == 3 && got
-	obj.AddAtIndex(2, 2) // linked list becomes 1->3->2
-	got = obj.Get(5) == -1 && got
-	if !got {
-		t.Fatalf("got: %v, want: %v", got, true)
-	}
-}
diff --git a/problems/design-log-storage-system/README.md b/problems/design-log-storage-system/README.md
deleted file mode 100644
index 9f35d631e..000000000
--- a/problems/design-log-storage-system/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-derangement-of-an-array "Find the Derangement of An Array")
-　　　　　　　　　　　　　　　　
-[Next >](../exclusive-time-of-functions "Exclusive Time of Functions")
-
-## [635. Design Log Storage System (Medium)](https://leetcode.com/problems/design-log-storage-system "设计日志存储系统")
-
-<p>You are given several logs that each log contains a unique id and timestamp. Timestamp is a string that has the following format: <code>Year:Month:Day:Hour:Minute:Second</code>, for example, <code>2017:01:01:23:59:59</code>. All domains are zero-padded decimal numbers. </p>
-
-<p>Design a log storage system to implement the following functions:</p>
-
-<p><code>void Put(int id, string timestamp)</code>: Given a log's unique id and timestamp, store the log in your storage system.</p>
-<br>
-<p><code>int[] Retrieve(String start, String end, String granularity)</code>: Return the id of logs whose timestamps are within the range from start to end. Start and end all have the same format as timestamp. However, granularity means the time level for consideration. For example, start = "2017:01:01:23:59:59", end = "2017:01:02:23:59:59", granularity = "Day", it means that we need to find the logs within the range from Jan. 1st 2017 to Jan. 2nd 2017.</p>
-
-<p><b>Example 1:</b><br />
-<pre>
-put(1, "2017:01:01:23:59:59");
-put(2, "2017:01:01:22:59:59");
-put(3, "2016:01:01:00:00:00");
-retrieve("2016:01:01:01:01:01","2017:01:01:23:00:00","Year"); // return [1,2,3], because you need to return all logs within 2016 and 2017.
-retrieve("2016:01:01:01:01:01","2017:01:01:23:00:00","Hour"); // return [1,2], because you need to return all logs start from 2016:01:01:01 to 2017:01:01:23, where log 3 is left outside the range.
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>There will be at most 300 operations of Put or Retrieve.</li>
-<li>Year ranges from [2000,2017]. Hour ranges from [00,23].</li>
-<li>Output for Retrieve has no order required.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [Design In-Memory File System](../design-in-memory-file-system) (Hard)
diff --git a/problems/design-log-storage-system/design_log_storage_system.go b/problems/design-log-storage-system/design_log_storage_system.go
deleted file mode 100644
index f1d68a92c..000000000
--- a/problems/design-log-storage-system/design_log_storage_system.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem635
diff --git a/problems/design-log-storage-system/design_log_storage_system_test.go b/problems/design-log-storage-system/design_log_storage_system_test.go
deleted file mode 100644
index f1d68a92c..000000000
--- a/problems/design-log-storage-system/design_log_storage_system_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem635
diff --git a/problems/design-most-recently-used-queue/README.md b/problems/design-most-recently-used-queue/README.md
deleted file mode 100644
index b2b8f0d02..000000000
--- a/problems/design-most-recently-used-queue/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../closest-subsequence-sum "Closest Subsequence Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../recyclable-and-low-fat-products "Recyclable and Low Fat Products")
-
-## [1756. Design Most Recently Used Queue (Medium)](https://leetcode.com/problems/design-most-recently-used-queue "设计最近使用（MRU）队列")
-
-
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can store the data in an array and apply each fetch by moving the ith element to the end of the array (i.e, O(n) per operation).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-A better way is to use the square root decomposition technique.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can build chunks of size sqrt(n). For each fetch operation, You can search for the chunk which has the ith element and update it (i.e., O(sqrt(n)) per operation), and move this element to an empty chunk at the end.
-</details>
diff --git a/problems/design-movie-rental-system/README.md b/problems/design-movie-rental-system/README.md
deleted file mode 100644
index 8f579b4f1..000000000
--- a/problems/design-movie-rental-system/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-alternating-subsequence-sum "Maximum Alternating Subsequence Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-product-difference-between-two-pairs "Maximum Product Difference Between Two Pairs")
-
-## [1912. Design Movie Rental System (Hard)](https://leetcode.com/problems/design-movie-rental-system "设计电影租借系统")
-
-<p>You have a movie renting company consisting of <code>n</code> shops. You want to implement a renting system that supports searching for, booking, and returning movies. The system should also support generating a report of the currently rented movies.</p>
-
-<p>Each movie is given as a 2D integer array <code>entries</code> where <code>entries[i] = [shop<sub>i</sub>, movie<sub>i</sub>, price<sub>i</sub>]</code> indicates that there is a copy of movie <code>movie<sub>i</sub></code> at shop <code>shop<sub>i</sub></code> with a rental price of <code>price<sub>i</sub></code>. Each shop carries <strong>at most one</strong> copy of a movie <code>movie<sub>i</sub></code>.</p>
-
-<p>The system should support the following functions:</p>
-
-<ul>
-	<li><strong>Search</strong>: Finds the <strong>cheapest 5 shops</strong> that have an <strong>unrented copy</strong> of a given movie. The shops should be sorted by <strong>price</strong> in ascending order, and in case of a tie, the one with the <strong>smaller </strong><code>shop<sub>i</sub></code> should appear first. If there are less than 5 matching shops, then all of them should be returned. If no shop has an unrented copy, then an empty list should be returned.</li>
-	<li><strong>Rent</strong>: Rents an <strong>unrented copy</strong> of a given movie from a given shop.</li>
-	<li><strong>Drop</strong>: Drops off a <strong>previously rented copy</strong> of a given movie at a given shop.</li>
-	<li><strong>Report</strong>: Returns the <strong>cheapest 5 rented movies</strong> (possibly of the same movie ID) as a 2D list <code>res</code> where <code>res[j] = [shop<sub>j</sub>, movie<sub>j</sub>]</code> describes that the <code>j<sup>th</sup></code> cheapest rented movie <code>movie<sub>j</sub></code> was rented from the shop <code>shop<sub>j</sub></code>. The movies in <code>res</code> should be sorted by <strong>price </strong>in ascending order, and in case of a tie, the one with the <strong>smaller </strong><code>shop<sub>j</sub></code> should appear first, and if there is still tie, the one with the <strong>smaller </strong><code>movie<sub>j</sub></code> should appear first. If there are fewer than 5 rented movies, then all of them should be returned. If no movies are currently being rented, then an empty list should be returned.</li>
-</ul>
-
-<p>Implement the <code>MovieRentingSystem</code> class:</p>
-
-<ul>
-	<li><code>MovieRentingSystem(int n, int[][] entries)</code> Initializes the <code>MovieRentingSystem</code> object with <code>n</code> shops and the movies in <code>entries</code>.</li>
-	<li><code>List&lt;Integer&gt; search(int movie)</code> Returns a list of shops that have an <strong>unrented copy</strong> of the given <code>movie</code> as described above.</li>
-	<li><code>void rent(int shop, int movie)</code> Rents the given <code>movie</code> from the given <code>shop</code>.</li>
-	<li><code>void drop(int shop, int movie)</code> Drops off a previously rented <code>movie</code> at the given <code>shop</code>.</li>
-	<li><code>List&lt;List&lt;Integer&gt;&gt; report()</code> Returns a list of cheapest <strong>rented</strong> movies as described above.</li>
-</ul>
-
-<p><strong>Note:</strong> The test cases will be generated such that <code>rent</code> will only be called if the shop has an <strong>unrented</strong> copy of the movie, and <code>drop</code> will only be called if the shop had <strong>previously rented</strong> out the movie.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MovieRentingSystem&quot;, &quot;search&quot;, &quot;rent&quot;, &quot;rent&quot;, &quot;report&quot;, &quot;drop&quot;, &quot;search&quot;]
-[[3, [[0, 1, 5], [0, 2, 6], [0, 3, 7], [1, 1, 4], [1, 2, 7], [2, 1, 5]]], [1], [0, 1], [1, 2], [], [1, 2], [2]]
-<strong>Output</strong>
-[null, [1, 0, 2], null, null, [[0, 1], [1, 2]], null, [0, 1]]
-
-<strong>Explanation</strong>
-MovieRentingSystem movieRentingSystem = new MovieRentingSystem(3, [[0, 1, 5], [0, 2, 6], [0, 3, 7], [1, 1, 4], [1, 2, 7], [2, 1, 5]]);
-movieRentingSystem.search(1);  // return [1, 0, 2], Movies of ID 1 are unrented at shops 1, 0, and 2. Shop 1 is cheapest; shop 0 and 2 are the same price, so order by shop number.
-movieRentingSystem.rent(0, 1); // Rent movie 1 from shop 0. Unrented movies at shop 0 are now [2,3].
-movieRentingSystem.rent(1, 2); // Rent movie 2 from shop 1. Unrented movies at shop 1 are now [1].
-movieRentingSystem.report();   // return [[0, 1], [1, 2]]. Movie 1 from shop 0 is cheapest, followed by movie 2 from shop 1.
-movieRentingSystem.drop(1, 2); // Drop off movie 2 at shop 1. Unrented movies at shop 1 are now [1,2].
-movieRentingSystem.search(2);  // return [0, 1]. Movies of ID 2 are unrented at shops 0 and 1. Shop 0 is cheapest, followed by shop 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 3 * 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= entries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= shop<sub>i</sub> &lt; n</code></li>
-	<li><code>1 &lt;= movie<sub>i</sub>, price<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li>Each shop carries <strong>at most one</strong> copy of a movie <code>movie<sub>i</sub></code>.</li>
-	<li>At most <code>10<sup>5</sup></code> calls <strong>in total</strong> will be made to <code>search</code>, <code>rent</code>, <code>drop</code> and <code>report</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You need to maintain a sorted list for each movie and a sorted list for rented movies
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When renting a movie remove it from its movies sorted list and added it to the rented list and vice versa in the case of dropping a movie
-</details>
diff --git a/problems/design-parking-system/README.md b/problems/design-parking-system/README.md
deleted file mode 100644
index 3b78047ab..000000000
--- a/problems/design-parking-system/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-nearest-right-node-in-binary-tree "Find Nearest Right Node in Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../alert-using-same-key-card-three-or-more-times-in-a-one-hour-period "Alert Using Same Key-Card Three or More Times in a One Hour Period")
-
-## [1603. Design Parking System (Easy)](https://leetcode.com/problems/design-parking-system "设计停车系统")
-
-<p>Design a parking system for a parking lot. The parking lot has three kinds of parking spaces: big, medium, and small, with a fixed number of slots for each size.</p>
-
-<p>Implement the <code>ParkingSystem</code> class:</p>
-
-<ul>
-	<li><code>ParkingSystem(int big, int medium, int small)</code> Initializes object of the <code>ParkingSystem</code> class. The number of slots for each parking space are given as part of the constructor.</li>
-	<li><code>bool addCar(int carType)</code> Checks whether there is a parking space of <code>carType</code> for the car that wants to get into the parking lot. <code>carType</code> can be of three kinds: big, medium, or small, which are represented by <code>1</code>, <code>2</code>, and <code>3</code> respectively. <strong>A car can only park in a parking space of its </strong><code>carType</code>. If there is no space available, return <code>false</code>, else park the car in that size space and return <code>true</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;ParkingSystem&quot;, &quot;addCar&quot;, &quot;addCar&quot;, &quot;addCar&quot;, &quot;addCar&quot;]
-[[1, 1, 0], [1], [2], [3], [1]]
-<strong>Output</strong>
-[null, true, true, false, false]
-
-<strong>Explanation</strong>
-ParkingSystem parkingSystem = new ParkingSystem(1, 1, 0);
-parkingSystem.addCar(1); // return true because there is 1 available slot for a big car
-parkingSystem.addCar(2); // return true because there is 1 available slot for a medium car
-parkingSystem.addCar(3); // return false because there is no available slot for a small car
-parkingSystem.addCar(1); // return false because there is no available slot for a big car. It is already occupied.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= big, medium, small &lt;= 1000</code></li>
-	<li><code>carType</code> is <code>1</code>, <code>2</code>, or <code>3</code></li>
-	<li>At most <code>1000</code> calls will be made to <code>addCar</code></li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Record number of parking slots still available for each car type.
-</details>
diff --git a/problems/design-phone-directory/README.md b/problems/design-phone-directory/README.md
deleted file mode 100644
index b25857881..000000000
--- a/problems/design-phone-directory/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-smallest-element-in-a-sorted-matrix "Kth Smallest Element in a Sorted Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../insert-delete-getrandom-o1 "Insert Delete GetRandom O(1)")
-
-## [379. Design Phone Directory (Medium)](https://leetcode.com/problems/design-phone-directory "电话目录管理系统")
-
-<p>Design a Phone Directory which supports the following operations:</p>
-
-<p>
-<ol>
-<li><code>get</code>: Provide a number which is not assigned to anyone.</li>
-<li><code>check</code>: Check if a number is available or not.</li>
-<li><code>release</code>: Recycle or release a number.</li>
-</ol>
-</p>
-
-<p><b>Example:</b>
-<pre>
-// Init a phone directory containing a total of 3 numbers: 0, 1, and 2.
-PhoneDirectory directory = new PhoneDirectory(3);
-
-// It can return any available phone number. Here we assume it returns 0.
-directory.get();
-
-// Assume it returns 1.
-directory.get();
-
-// The number 2 is available, so return true.
-directory.check(2);
-
-// It returns 2, the only number that is left.
-directory.get();
-
-// The number 2 is no longer available, so return false.
-directory.check(2);
-
-// Release number 2 back to the pool.
-directory.release(2);
-
-// Number 2 is available again, return true.
-directory.check(2);
-</pre>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-
-### Similar Questions
-  1. [Seat Reservation Manager](../seat-reservation-manager) (Medium)
diff --git a/problems/design-phone-directory/design_phone_directory.go b/problems/design-phone-directory/design_phone_directory.go
deleted file mode 100644
index d42639ae6..000000000
--- a/problems/design-phone-directory/design_phone_directory.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem379
diff --git a/problems/design-phone-directory/design_phone_directory_test.go b/problems/design-phone-directory/design_phone_directory_test.go
deleted file mode 100644
index d42639ae6..000000000
--- a/problems/design-phone-directory/design_phone_directory_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem379
diff --git a/problems/design-search-autocomplete-system/README.md b/problems/design-search-autocomplete-system/README.md
deleted file mode 100644
index a42e4d98b..000000000
--- a/problems/design-search-autocomplete-system/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-circular-deque "Design Circular Deque")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-average-subarray-i "Maximum Average Subarray I")
-
-## [642. Design Search Autocomplete System (Hard)](https://leetcode.com/problems/design-search-autocomplete-system "设计搜索自动补全系统")
-
-<p>Design a search autocomplete system for a search engine. Users may input a sentence (at least one word and end with a special character <code>&#39;#&#39;</code>). For <b>each character</b> they type <b>except &#39;#&#39;</b>, you need to return the <b>top 3</b> historical hot sentences that have prefix the same as the part of sentence already typed. Here are the specific rules:</p>
-
-<ol>
-	<li>The hot degree for a sentence is defined as the number of times a user typed the exactly same sentence before.</li>
-	<li>The returned top 3 hot sentences should be sorted by hot degree (The first is the hottest one). If several sentences have the same degree of hot, you need to use ASCII-code order (smaller one appears first).</li>
-	<li>If less than 3 hot sentences exist, then just return as many as you can.</li>
-	<li>When the input is a special character, it means the sentence ends, and in this case, you need to return an empty list.</li>
-</ol>
-
-<p>Your job is to implement the following functions:</p>
-
-<p>The constructor function:</p>
-
-<p><code>AutocompleteSystem(String[] sentences, int[] times):</code> This is the constructor. The input is <b>historical data</b>. <code>Sentences</code> is a string array consists of previously typed sentences. <code>Times</code> is the corresponding times a sentence has been typed. Your system should record these historical data.</p>
-
-<p>Now, the user wants to input a new sentence. The following function will provide the next character the user types:</p>
-
-<p><code>List&lt;String&gt; input(char c):</code> The input <code>c</code> is the next character typed by the user. The character will only be lower-case letters (<code>&#39;a&#39;</code> to <code>&#39;z&#39;</code>), blank space (<code>&#39; &#39;</code>) or a special character (<code>&#39;#&#39;</code>). Also, the previously typed sentence should be recorded in your system. The output will be the <b>top 3</b> historical hot sentences that have prefix the same as the part of sentence already typed.</p>
-&nbsp;
-
-<p><b>Example:</b><br />
-<b>Operation:</b> AutocompleteSystem([&quot;i love you&quot;, &quot;island&quot;,&quot;ironman&quot;, &quot;i love leetcode&quot;], [5,3,2,2])<br />
-The system have already tracked down the following sentences and their corresponding times:<br />
-<code>&quot;i love you&quot;</code> : <code>5</code> times<br />
-<code>&quot;island&quot;</code> : <code>3</code> times<br />
-<code>&quot;ironman&quot;</code> : <code>2</code> times<br />
-<code>&quot;i love leetcode&quot;</code> : <code>2</code> times<br />
-Now, the user begins another search:<br />
-<br />
-<b>Operation:</b> input(&#39;i&#39;)<br />
-<b>Output:</b> [&quot;i love you&quot;, &quot;island&quot;,&quot;i love leetcode&quot;]<br />
-<b>Explanation:</b><br />
-There are four sentences that have prefix <code>&quot;i&quot;</code>. Among them, &quot;ironman&quot; and &quot;i love leetcode&quot; have same hot degree. Since <code>&#39; &#39;</code> has ASCII code 32 and <code>&#39;r&#39;</code> has ASCII code 114, &quot;i love leetcode&quot; should be in front of &quot;ironman&quot;. Also we only need to output top 3 hot sentences, so &quot;ironman&quot; will be ignored.<br />
-<br />
-<b>Operation:</b> input(&#39; &#39;)<br />
-<b>Output:</b> [&quot;i love you&quot;,&quot;i love leetcode&quot;]<br />
-<b>Explanation:</b><br />
-There are only two sentences that have prefix <code>&quot;i &quot;</code>.<br />
-<br />
-<b>Operation:</b> input(&#39;a&#39;)<br />
-<b>Output:</b> []<br />
-<b>Explanation:</b><br />
-There are no sentences that have prefix <code>&quot;i a&quot;</code>.<br />
-<br />
-<b>Operation:</b> input(&#39;#&#39;)<br />
-<b>Output:</b> []<br />
-<b>Explanation:</b><br />
-The user finished the input, the sentence <code>&quot;i a&quot;</code> should be saved as a historical sentence in system. And the following input will be counted as a new search.</p>
-&nbsp;
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>The input sentence will always start with a letter and end with &#39;#&#39;, and only one blank space will exist between two words.</li>
-	<li>The number of <b>complete sentences</b> that to be searched won&#39;t exceed 100. The length of each sentence including those in the historical data won&#39;t exceed 100.</li>
-	<li>Please use double-quote instead of single-quote when you write test cases even for a character input.</li>
-	<li>Please remember to <b>RESET</b> your class variables declared in class AutocompleteSystem, as static/class variables are <b>persisted across multiple test cases</b>. Please see <a href="https://leetcode.com/faq/#different-output">here</a> for more details.</li>
-</ol>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Similar Questions
-  1. [Implement Trie (Prefix Tree)](../implement-trie-prefix-tree) (Medium)
diff --git a/problems/design-search-autocomplete-system/design_search_autocomplete_system.go b/problems/design-search-autocomplete-system/design_search_autocomplete_system.go
deleted file mode 100644
index 6c62cec21..000000000
--- a/problems/design-search-autocomplete-system/design_search_autocomplete_system.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem642
diff --git a/problems/design-search-autocomplete-system/design_search_autocomplete_system_test.go b/problems/design-search-autocomplete-system/design_search_autocomplete_system_test.go
deleted file mode 100644
index 6c62cec21..000000000
--- a/problems/design-search-autocomplete-system/design_search_autocomplete_system_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem642
diff --git a/problems/design-skiplist/README.md b/problems/design-skiplist/README.md
deleted file mode 100644
index 07f2933c2..000000000
--- a/problems/design-skiplist/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../monthly-transactions-ii "Monthly Transactions II")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-number-of-occurrences "Unique Number of Occurrences")
-
-## [1206. Design Skiplist (Hard)](https://leetcode.com/problems/design-skiplist "设计跳表")
-
-<p>Design a <strong>Skiplist</strong> without using any built-in libraries.</p>
-
-<p>A <strong>skiplist</strong> is a data structure that takes <code>O(log(n))</code> time to add, erase and search. Comparing with treap and red-black tree which has the same function and performance, the code length of Skiplist can be comparatively short and the idea behind Skiplists is just simple linked lists.</p>
-
-<p>For example, we have a Skiplist containing <code>[30,40,50,60,70,90]</code> and we want to add <code>80</code> and <code>45</code> into it. The Skiplist works this way:</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/09/27/1506_skiplist.gif" style="width: 500px; height: 173px;" /><br />
-<small>Artyom Kalinin [CC BY-SA 3.0], via <a href="https://commons.wikimedia.org/wiki/File:Skip_list_add_element-en.gif" target="_blank" title="Artyom Kalinin [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons">Wikimedia Commons</a></small></p>
-
-<p>You can see there are many layers in the Skiplist. Each layer is a sorted linked list. With the help of the top layers, add, erase and search can be faster than <code>O(n)</code>. It can be proven that the average time complexity for each operation is <code>O(log(n))</code> and space complexity is <code>O(n)</code>.</p>
-
-<p>See more about Skiplist: <a href="https://en.wikipedia.org/wiki/Skip_list" target="_blank">https://en.wikipedia.org/wiki/Skip_list</a></p>
-
-<p>Implement the <code>Skiplist</code> class:</p>
-
-<ul>
-	<li><code>Skiplist()</code> Initializes the object of the skiplist.</li>
-	<li><code>bool search(int target)</code> Returns <code>true</code> if the integer <code>target</code> exists in the Skiplist or <code>false</code> otherwise.</li>
-	<li><code>void add(int num)</code> Inserts the value <code>num</code> into the SkipList.</li>
-	<li><code>bool erase(int num)</code> Removes the value <code>num</code> from the Skiplist and returns <code>true</code>. If <code>num</code> does not exist in the Skiplist, do nothing and return <code>false</code>. If there exist multiple <code>num</code> values, removing any one of them is fine.</li>
-</ul>
-
-<p>Note that duplicates may exist in the Skiplist, your code needs to handle this situation.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Skiplist&quot;, &quot;add&quot;, &quot;add&quot;, &quot;add&quot;, &quot;search&quot;, &quot;add&quot;, &quot;search&quot;, &quot;erase&quot;, &quot;erase&quot;, &quot;search&quot;]
-[[], [1], [2], [3], [0], [4], [1], [0], [1], [1]]
-<strong>Output</strong>
-[null, null, null, null, false, null, true, false, true, false]
-
-<strong>Explanation</strong>
-Skiplist skiplist = new Skiplist();
-skiplist.add(1);
-skiplist.add(2);
-skiplist.add(3);
-skiplist.search(0); // return False
-skiplist.add(4);
-skiplist.search(1); // return True
-skiplist.erase(0);  // return False, 0 is not in skiplist.
-skiplist.erase(1);  // return True
-skiplist.search(1); // return False, 1 has already been erased.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= num, target &lt;= 2 * 10<sup>4</sup></code></li>
-	<li>At most <code>5 * 10<sup>4</sup></code> calls will be made to <code>search</code>, <code>add</code>, and <code>erase</code>.</li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Similar Questions
-  1. [Design HashSet](../design-hashset) (Easy)
-  1. [Design HashMap](../design-hashmap) (Easy)
-  1. [Design Linked List](../design-linked-list) (Medium)
diff --git a/problems/design-snake-game/README.md b/problems/design-snake-game/README.md
deleted file mode 100644
index d4a133824..000000000
--- a/problems/design-snake-game/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../data-stream-as-disjoint-intervals "Data Stream as Disjoint Intervals")
-　　　　　　　　　　　　　　　　
-[Next >](../russian-doll-envelopes "Russian Doll Envelopes")
-
-## [353. Design Snake Game (Medium)](https://leetcode.com/problems/design-snake-game "贪吃蛇")
-
-<p>Design a <a href="https://en.wikipedia.org/wiki/Snake_(video_game)" target="_blank">Snake game</a> that is played on a device with screen size = <i>width</i> x <i>height</i>. <a href="http://patorjk.com/games/snake/" target="_blank">Play the game online</a> if you are not familiar with the game.</p>
-
-<p>The snake is initially positioned at the top left corner (0,0) with length = 1 unit.</p>
-
-<p>You are given a list of food&#39;s positions in row-column order. When a snake eats the food, its length and the game&#39;s score both increase by 1.</p>
-
-<p>Each food appears one by one on the screen. For example, the second food will not appear until the first food was eaten by the snake.</p>
-
-<p>When a food does appear on the screen, it is guaranteed that it will not appear on a block occupied by the snake.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-Given width = 3, height = 2, and food = [[1,2],[0,1]].
-
-Snake snake = new Snake(width, height, food);
-
-Initially the snake appears at position (0,0) and the food at (1,2).
-
-|S| | |
-| | |F|
-
-snake.move(&quot;R&quot;); -&gt; Returns 0
-
-| |S| |
-| | |F|
-
-snake.move(&quot;D&quot;); -&gt; Returns 0
-
-| | | |
-| |S|F|
-
-snake.move(&quot;R&quot;); -&gt; Returns 1 (Snake eats the first food and right after that, the second food appears at (0,1) )
-
-| |F| |
-| |S|S|
-
-snake.move(&quot;U&quot;); -&gt; Returns 1
-
-| |F|S|
-| | |S|
-
-snake.move(&quot;L&quot;); -&gt; Returns 2 (Snake eats the second food)
-
-| |S|S|
-| | |S|
-
-snake.move(&quot;U&quot;); -&gt; Returns -1 (Game over because snake collides with border)
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/design-snake-game/design_snake_game.go b/problems/design-snake-game/design_snake_game.go
deleted file mode 100644
index 251058e11..000000000
--- a/problems/design-snake-game/design_snake_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem353
diff --git a/problems/design-snake-game/design_snake_game_test.go b/problems/design-snake-game/design_snake_game_test.go
deleted file mode 100644
index 251058e11..000000000
--- a/problems/design-snake-game/design_snake_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem353
diff --git a/problems/design-tic-tac-toe/README.md b/problems/design-tic-tac-toe/README.md
deleted file mode 100644
index b724a798d..000000000
--- a/problems/design-tic-tac-toe/README.md
+++ /dev/null
@@ -1,90 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../top-k-frequent-elements "Top K Frequent Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../intersection-of-two-arrays "Intersection of Two Arrays")
-
-## [348. Design Tic-Tac-Toe (Medium)](https://leetcode.com/problems/design-tic-tac-toe "设计井字棋")
-
-<p>Design a Tic-tac-toe game that is played between two players on a <i>n</i> x <i>n</i> grid.
-</p>
-
-<p>You may assume the following rules:
-<ol>
-<li>A move is guaranteed to be valid and is placed on an empty block.</li>
-<li>Once a winning condition is reached, no more moves is allowed.</li>
-<li>A player who succeeds in placing <i>n</i> of their marks in a horizontal, vertical, or diagonal row wins the game.</li>
-</ol>
-</p>
-
-<p><b>Example:</b><br />
-<pre>
-Given <i>n</i> = 3, assume that player 1 is "X" and player 2 is "O" in the board.
-
-TicTacToe toe = new TicTacToe(3);
-
-toe.move(0, 0, 1); -> Returns 0 (no one wins)
-|X| | |
-| | | |    // Player 1 makes a move at (0, 0).
-| | | |
-
-toe.move(0, 2, 2); -> Returns 0 (no one wins)
-|X| |O|
-| | | |    // Player 2 makes a move at (0, 2).
-| | | |
-
-toe.move(2, 2, 1); -> Returns 0 (no one wins)
-|X| |O|
-| | | |    // Player 1 makes a move at (2, 2).
-| | |X|
-
-toe.move(1, 1, 2); -> Returns 0 (no one wins)
-|X| |O|
-| |O| |    // Player 2 makes a move at (1, 1).
-| | |X|
-
-toe.move(2, 0, 1); -> Returns 0 (no one wins)
-|X| |O|
-| |O| |    // Player 1 makes a move at (2, 0).
-|X| |X|
-
-toe.move(1, 0, 2); -> Returns 0 (no one wins)
-|X| |O|
-|O|O| |    // Player 2 makes a move at (1, 0).
-|X| |X|
-
-toe.move(2, 1, 1); -> Returns 1 (player 1 wins)
-|X| |O|
-|O|O| |    // Player 1 makes a move at (2, 1).
-|X|X|X|
-</pre>
-</p>
-
-<p><b>Follow up:</b><br />
-Could you do better than O(<i>n</i><sup>2</sup>) per <code>move()</code> operation?
-</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Valid Tic-Tac-Toe State](../valid-tic-tac-toe-state) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could you trade extra space such that <code>move()</code> operation can be done in O(1)?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You need two arrays: int rows[n], int cols[n], plus two variables: diagonal, anti_diagonal.
-</details>
diff --git a/problems/design-tic-tac-toe/design_tic_tac_toe.go b/problems/design-tic-tac-toe/design_tic_tac_toe.go
deleted file mode 100644
index fe3652311..000000000
--- a/problems/design-tic-tac-toe/design_tic_tac_toe.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem348
diff --git a/problems/design-tic-tac-toe/design_tic_tac_toe_test.go b/problems/design-tic-tac-toe/design_tic_tac_toe_test.go
deleted file mode 100644
index fe3652311..000000000
--- a/problems/design-tic-tac-toe/design_tic_tac_toe_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem348
diff --git a/problems/design-twitter/README.md b/problems/design-twitter/README.md
deleted file mode 100644
index 3a8f47caf..000000000
--- a/problems/design-twitter/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../russian-doll-envelopes "Russian Doll Envelopes")
-　　　　　　　　　　　　　　　　
-[Next >](../line-reflection "Line Reflection")
-
-## [355. Design Twitter (Medium)](https://leetcode.com/problems/design-twitter "设计推特")
-
-<p>Design a simplified version of Twitter where users can post tweets, follow/unfollow another user, and is able to see the <code>10</code> most recent tweets in the user&#39;s news feed.</p>
-
-<p>Implement the <code>Twitter</code> class:</p>
-
-<ul>
-	<li><code>Twitter()</code> Initializes your twitter object.</li>
-	<li><code>void postTweet(int userId, int tweetId)</code> Composes a new tweet with ID <code>tweetId</code> by the user <code>userId</code>. Each call to this function will be made with a unique <code>tweetId</code>.</li>
-	<li><code>List&lt;Integer&gt; getNewsFeed(int userId)</code> Retrieves the <code>10</code> most recent tweet IDs in the user&#39;s news feed. Each item in the news feed must be posted by users who the user followed or by the user themself. Tweets must be <strong>ordered from most recent to least recent</strong>.</li>
-	<li><code>void follow(int followerId, int followeeId)</code> The user with ID <code>followerId</code> started following the user with ID <code>followeeId</code>.</li>
-	<li><code>void unfollow(int followerId, int followeeId)</code> The user with ID <code>followerId</code> started unfollowing the user with ID <code>followeeId</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Twitter&quot;, &quot;postTweet&quot;, &quot;getNewsFeed&quot;, &quot;follow&quot;, &quot;postTweet&quot;, &quot;getNewsFeed&quot;, &quot;unfollow&quot;, &quot;getNewsFeed&quot;]
-[[], [1, 5], [1], [1, 2], [2, 6], [1], [1, 2], [1]]
-<strong>Output</strong>
-[null, null, [5], null, null, [6, 5], null, [5]]
-
-<strong>Explanation</strong>
-Twitter twitter = new Twitter();
-twitter.postTweet(1, 5); // User 1 posts a new tweet (id = 5).
-twitter.getNewsFeed(1);  // User 1&#39;s news feed should return a list with 1 tweet id -&gt; [5]. return [5]
-twitter.follow(1, 2);    // User 1 follows user 2.
-twitter.postTweet(2, 6); // User 2 posts a new tweet (id = 6).
-twitter.getNewsFeed(1);  // User 1&#39;s news feed should return a list with 2 tweet ids -&gt; [6, 5]. Tweet id 6 should precede tweet id 5 because it is posted after tweet id 5.
-twitter.unfollow(1, 2);  // User 1 unfollows user 2.
-twitter.getNewsFeed(1);  // User 1&#39;s news feed should return a list with 1 tweet id -&gt; [5], since user 1 is no longer following user 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= userId, followerId, followeeId &lt;= 500</code></li>
-	<li><code>0 &lt;= tweetId &lt;= 10<sup>4</sup></code></li>
-	<li>All the tweets have <strong>unique</strong> IDs.</li>
-	<li>At most <code>3 * 10<sup>4</sup></code> calls will be made to <code>postTweet</code>, <code>getNewsFeed</code>, <code>follow</code>, and <code>unfollow</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
diff --git a/problems/design-twitter/design_twitter.go b/problems/design-twitter/design_twitter.go
deleted file mode 100644
index ac970f243..000000000
--- a/problems/design-twitter/design_twitter.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem355
diff --git a/problems/design-twitter/design_twitter_test.go b/problems/design-twitter/design_twitter_test.go
deleted file mode 100644
index ac970f243..000000000
--- a/problems/design-twitter/design_twitter_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem355
diff --git a/problems/design-underground-system/README.md b/problems/design-underground-system/README.md
deleted file mode 100644
index 07d725874..000000000
--- a/problems/design-underground-system/README.md
+++ /dev/null
@@ -1,115 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-number-of-teams "Count Number of Teams")
-　　　　　　　　　　　　　　　　
-[Next >](../find-all-good-strings "Find All Good Strings")
-
-## [1396. Design Underground System (Medium)](https://leetcode.com/problems/design-underground-system "设计地铁系统")
-
-<p>An underground railway system is keeping track of customer travel times between different stations. They are using this data to calculate the average time it takes to travel from one station to another.</p>
-
-<p>Implement the <code>UndergroundSystem</code> class:</p>
-
-<ul>
-	<li><code>void checkIn(int id, string stationName, int t)</code>
-	<ul>
-		<li>A customer with a card ID equal to <code>id</code>, checks in at the station <code>stationName</code> at time <code>t</code>.</li>
-		<li>A customer can only be checked into one place at a time.</li>
-	</ul>
-	</li>
-	<li><code>void checkOut(int id, string stationName, int t)</code>
-	<ul>
-		<li>A customer with a card ID equal to <code>id</code>, checks out from the station <code>stationName</code> at time <code>t</code>.</li>
-	</ul>
-	</li>
-	<li><code>double getAverageTime(string startStation, string endStation)</code>
-	<ul>
-		<li>Returns the average time it takes to travel from <code>startStation</code> to <code>endStation</code>.</li>
-		<li>The average time is computed from all the previous traveling times from <code>startStation</code> to <code>endStation</code> that happened <strong>directly</strong>, meaning a check in at <code>startStation</code> followed by a check out from <code>endStation</code>.</li>
-		<li>The time it takes to travel from <code>startStation</code> to <code>endStation</code> <strong>may be different</strong> from the time it takes to travel from <code>endStation</code> to <code>startStation</code>.</li>
-		<li>There will be at least one customer that has traveled from <code>startStation</code> to <code>endStation</code> before <code>getAverageTime</code> is called.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>You may assume all calls to the <code>checkIn</code> and <code>checkOut</code> methods are consistent. If a customer checks in at time <code>t<sub>1</sub></code> then checks out at time <code>t<sub>2</sub></code>, then <code>t<sub>1</sub> &lt; t<sub>2</sub></code>. All events happen in chronological order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;UndergroundSystem&quot;,&quot;checkIn&quot;,&quot;checkIn&quot;,&quot;checkIn&quot;,&quot;checkOut&quot;,&quot;checkOut&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;,&quot;getAverageTime&quot;,&quot;checkIn&quot;,&quot;getAverageTime&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;]
-[[],[45,&quot;Leyton&quot;,3],[32,&quot;Paradise&quot;,8],[27,&quot;Leyton&quot;,10],[45,&quot;Waterloo&quot;,15],[27,&quot;Waterloo&quot;,20],[32,&quot;Cambridge&quot;,22],[&quot;Paradise&quot;,&quot;Cambridge&quot;],[&quot;Leyton&quot;,&quot;Waterloo&quot;],[10,&quot;Leyton&quot;,24],[&quot;Leyton&quot;,&quot;Waterloo&quot;],[10,&quot;Waterloo&quot;,38],[&quot;Leyton&quot;,&quot;Waterloo&quot;]]
-
-<strong>Output</strong>
-[null,null,null,null,null,null,null,14.00000,11.00000,null,11.00000,null,12.00000]
-
-<strong>Explanation</strong>
-UndergroundSystem undergroundSystem = new UndergroundSystem();
-undergroundSystem.checkIn(45, &quot;Leyton&quot;, 3);
-undergroundSystem.checkIn(32, &quot;Paradise&quot;, 8);
-undergroundSystem.checkIn(27, &quot;Leyton&quot;, 10);
-undergroundSystem.checkOut(45, &quot;Waterloo&quot;, 15);  // Customer 45 &quot;Leyton&quot; -&gt; &quot;Waterloo&quot; in 15-3 = 12
-undergroundSystem.checkOut(27, &quot;Waterloo&quot;, 20);  // Customer 27 &quot;Leyton&quot; -&gt; &quot;Waterloo&quot; in 20-10 = 10
-undergroundSystem.checkOut(32, &quot;Cambridge&quot;, 22); // Customer 32 &quot;Paradise&quot; -&gt; &quot;Cambridge&quot; in 22-8 = 14
-undergroundSystem.getAverageTime(&quot;Paradise&quot;, &quot;Cambridge&quot;); // return 14.00000. One trip &quot;Paradise&quot; -&gt; &quot;Cambridge&quot;, (14) / 1 = 14
-undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Waterloo&quot;);    // return 11.00000. Two trips &quot;Leyton&quot; -&gt; &quot;Waterloo&quot;, (10 + 12) / 2 = 11
-undergroundSystem.checkIn(10, &quot;Leyton&quot;, 24);
-undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Waterloo&quot;);    // return 11.00000
-undergroundSystem.checkOut(10, &quot;Waterloo&quot;, 38);  // Customer 10 &quot;Leyton&quot; -&gt; &quot;Waterloo&quot; in 38-24 = 14
-undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Waterloo&quot;);    // return 12.00000. Three trips &quot;Leyton&quot; -&gt; &quot;Waterloo&quot;, (10 + 12 + 14) / 3 = 12
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;UndergroundSystem&quot;,&quot;checkIn&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;,&quot;checkIn&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;,&quot;checkIn&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;]
-[[],[10,&quot;Leyton&quot;,3],[10,&quot;Paradise&quot;,8],[&quot;Leyton&quot;,&quot;Paradise&quot;],[5,&quot;Leyton&quot;,10],[5,&quot;Paradise&quot;,16],[&quot;Leyton&quot;,&quot;Paradise&quot;],[2,&quot;Leyton&quot;,21],[2,&quot;Paradise&quot;,30],[&quot;Leyton&quot;,&quot;Paradise&quot;]]
-
-<strong>Output</strong>
-[null,null,null,5.00000,null,null,5.50000,null,null,6.66667]
-
-<strong>Explanation</strong>
-UndergroundSystem undergroundSystem = new UndergroundSystem();
-undergroundSystem.checkIn(10, &quot;Leyton&quot;, 3);
-undergroundSystem.checkOut(10, &quot;Paradise&quot;, 8); // Customer 10 &quot;Leyton&quot; -&gt; &quot;Paradise&quot; in 8-3 = 5
-undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Paradise&quot;); // return 5.00000, (5) / 1 = 5
-undergroundSystem.checkIn(5, &quot;Leyton&quot;, 10);
-undergroundSystem.checkOut(5, &quot;Paradise&quot;, 16); // Customer 5 &quot;Leyton&quot; -&gt; &quot;Paradise&quot; in 16-10 = 6
-undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Paradise&quot;); // return 5.50000, (5 + 6) / 2 = 5.5
-undergroundSystem.checkIn(2, &quot;Leyton&quot;, 21);
-undergroundSystem.checkOut(2, &quot;Paradise&quot;, 30); // Customer 2 &quot;Leyton&quot; -&gt; &quot;Paradise&quot; in 30-21 = 9
-undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Paradise&quot;); // return 6.66667, (5 + 6 + 9) / 3 = 6.66667
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= id, t &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= stationName.length, startStation.length, endStation.length &lt;= 10</code></li>
-	<li>All strings consist of uppercase and lowercase English letters and digits.</li>
-	<li>There will be at most <code>2 * 10<sup>4</sup></code> calls <strong>in total</strong> to <code>checkIn</code>, <code>checkOut</code>, and <code>getAverageTime</code>.</li>
-	<li>Answers within <code>10<sup>-5</sup></code> of the actual value will be accepted.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Similar Questions
-  1. [Design Bitset](../design-bitset) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use two hash tables. The first to save the check-in time for a customer and the second to update the total time between two stations.
-</details>
diff --git a/problems/destination-city/README.md b/problems/destination-city/README.md
deleted file mode 100644
index 37239c418..000000000
--- a/problems/destination-city/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../create-a-session-bar-chart "Create a Session Bar Chart")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-all-1s-are-at-least-length-k-places-away "Check If All 1's Are at Least Length K Places Away")
-
-## [1436. Destination City (Easy)](https://leetcode.com/problems/destination-city "旅行终点站")
-
-<p>You are given the array <code>paths</code>, where <code>paths[i] = [cityA<sub>i</sub>, cityB<sub>i</sub>]</code> means there exists a direct path going from <code>cityA<sub>i</sub></code> to <code>cityB<sub>i</sub></code>. <em>Return the destination city, that is, the city without any path outgoing to another city.</em></p>
-
-<p>It is guaranteed that the graph of paths forms a line without any loop, therefore, there will be exactly one destination city.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> paths = [[&quot;London&quot;,&quot;New York&quot;],[&quot;New York&quot;,&quot;Lima&quot;],[&quot;Lima&quot;,&quot;Sao Paulo&quot;]]
-<strong>Output:</strong> &quot;Sao Paulo&quot; 
-<strong>Explanation:</strong> Starting at &quot;London&quot; city you will reach &quot;Sao Paulo&quot; city which is the destination city. Your trip consist of: &quot;London&quot; -&gt; &quot;New York&quot; -&gt; &quot;Lima&quot; -&gt; &quot;Sao Paulo&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> paths = [[&quot;B&quot;,&quot;C&quot;],[&quot;D&quot;,&quot;B&quot;],[&quot;C&quot;,&quot;A&quot;]]
-<strong>Output:</strong> &quot;A&quot;
-<strong>Explanation:</strong> All possible trips are:&nbsp;
-&quot;D&quot; -&gt; &quot;B&quot; -&gt; &quot;C&quot; -&gt; &quot;A&quot;.&nbsp;
-&quot;B&quot; -&gt; &quot;C&quot; -&gt; &quot;A&quot;.&nbsp;
-&quot;C&quot; -&gt; &quot;A&quot;.&nbsp;
-&quot;A&quot;.&nbsp;
-Clearly the destination city is &quot;A&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> paths = [[&quot;A&quot;,&quot;Z&quot;]]
-<strong>Output:</strong> &quot;Z&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= paths.length &lt;= 100</code></li>
-	<li><code>paths[i].length == 2</code></li>
-	<li><code>1 &lt;= cityA<sub>i</sub>.length, cityB<sub>i</sub>.length &lt;= 10</code></li>
-	<li><code>cityA<sub>i</sub> != cityB<sub>i</sub></code></li>
-	<li>All strings consist of lowercase and uppercase English letters and the space character.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Start in any city and use the path to move to the next city.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Eventually, you will reach a city with no path outgoing, this is the destination city.
-</details>
diff --git a/problems/destination-city/destination_city.go b/problems/destination-city/destination_city.go
deleted file mode 100644
index cfac2933c..000000000
--- a/problems/destination-city/destination_city.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem1436
-
-func destCity(paths [][]string) string {
-	m := make(map[string]bool)
-	for _, path := range paths {
-		m[path[0]] = true
-	}
-	for _, path := range paths {
-		if !m[path[1]] {
-			return path[1]
-		}
-	}
-	return ""
-}
diff --git a/problems/destination-city/destination_city_test.go b/problems/destination-city/destination_city_test.go
deleted file mode 100644
index c305e679d..000000000
--- a/problems/destination-city/destination_city_test.go
+++ /dev/null
@@ -1,48 +0,0 @@
-package problem1436
-
-import "testing"
-
-type testType struct {
-	in   [][]string
-	want string
-}
-
-func TestDestCity(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]string{
-				{"London", "New York"},
-				{"New York", "Lima"},
-				{"Lima", "Sao Paulo"},
-			},
-			want: "Sao Paulo",
-		},
-		{
-			in: [][]string{
-				{"B", "C"},
-				{"D", "B"},
-				{"C", "A"},
-			},
-			want: "A",
-		},
-		{
-			in: [][]string{
-				{"A", "Z"},
-			},
-			want: "Z",
-		},
-		{
-			in: [][]string{
-				{"A", "B"},
-				{"B", "A"},
-			},
-			want: "",
-		},
-	}
-	for _, tt := range tests {
-		got := destCity(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/destroying-asteroids/README.md b/problems/destroying-asteroids/README.md
deleted file mode 100644
index f1ff813bf..000000000
--- a/problems/destroying-asteroids/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-laser-beams-in-a-bank "Number of Laser Beams in a Bank")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-employees-to-be-invited-to-a-meeting "Maximum Employees to Be Invited to a Meeting")
-
-## [2126. Destroying Asteroids (Medium)](https://leetcode.com/problems/destroying-asteroids "摧毁小行星")
-
-<p>You are given an integer <code>mass</code>, which represents the original mass of a planet. You are further given an integer array <code>asteroids</code>, where <code>asteroids[i]</code> is the mass of the <code>i<sup>th</sup></code> asteroid.</p>
-
-<p>You can arrange for the planet to collide with the asteroids in <strong>any arbitrary order</strong>. If the mass of the planet is <b>greater than or equal to</b> the mass of the asteroid, the asteroid is <strong>destroyed</strong> and the planet <strong>gains</strong> the mass of the asteroid. Otherwise, the planet is destroyed.</p>
-
-<p>Return <code>true</code><em> if <strong>all</strong> asteroids can be destroyed. Otherwise, return </em><code>false</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> mass = 10, asteroids = [3,9,19,5,21]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> One way to order the asteroids is [9,19,5,3,21]:
-- The planet collides with the asteroid with a mass of 9. New planet mass: 10 + 9 = 19
-- The planet collides with the asteroid with a mass of 19. New planet mass: 19 + 19 = 38
-- The planet collides with the asteroid with a mass of 5. New planet mass: 38 + 5 = 43
-- The planet collides with the asteroid with a mass of 3. New planet mass: 43 + 3 = 46
-- The planet collides with the asteroid with a mass of 21. New planet mass: 46 + 21 = 67
-All asteroids are destroyed.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> mass = 5, asteroids = [4,9,23,4]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> 
-The planet cannot ever gain enough mass to destroy the asteroid with a mass of 23.
-After the planet destroys the other asteroids, it will have a mass of 5 + 4 + 9 + 4 = 22.
-This is less than 23, so a collision would not destroy the last asteroid.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= mass &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= asteroids.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= asteroids[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Choosing the asteroid to collide with can be done greedily.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If an asteroid will destroy the planet, then every bigger asteroid will also destroy the planet.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You only need to check the smallest asteroid at each collision. If it will destroy the planet, then every other asteroid will also destroy the planet.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Sort the asteroids in non-decreasing order by mass, then greedily try to collide with the asteroids in that order.
-</details>
diff --git a/problems/detect-capital/README.md b/problems/detect-capital/README.md
deleted file mode 100644
index c37869020..000000000
--- a/problems/detect-capital/README.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../random-flip-matrix "Random Flip Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-uncommon-subsequence-i "Longest Uncommon Subsequence I")
-
-## [520. Detect Capital (Easy)](https://leetcode.com/problems/detect-capital "检测大写字母")
-
-<p>We define the usage of capitals in a word to be right when one of the following cases holds:</p>
-
-<ul>
-	<li>All letters in this word are capitals, like <code>&quot;USA&quot;</code>.</li>
-	<li>All letters in this word are not capitals, like <code>&quot;leetcode&quot;</code>.</li>
-	<li>Only the first letter in this word is capital, like <code>&quot;Google&quot;</code>.</li>
-</ul>
-
-<p>Given a string <code>word</code>, return <code>true</code> if the usage of capitals in it is right.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> word = "USA"
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> word = "FlaG"
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length &lt;= 100</code></li>
-	<li><code>word</code> consists of lowercase and uppercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/detect-capital/detect_capital.go b/problems/detect-capital/detect_capital.go
deleted file mode 100644
index b53c6dfb3..000000000
--- a/problems/detect-capital/detect_capital.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem520
-
-import "unicode"
-
-func detectCapitalUse(word string) bool {
-	count := 0
-	for _, c := range word {
-		if unicode.IsUpper(c) {
-			count++
-		}
-	}
-	return count == 0 || count == len(word) || (count == 1 && unicode.IsUpper(rune(word[0])))
-}
diff --git a/problems/detect-capital/detect_capital_test.go b/problems/detect-capital/detect_capital_test.go
deleted file mode 100644
index 4f6a3435d..000000000
--- a/problems/detect-capital/detect_capital_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem520
-
-import "testing"
-
-type testType struct {
-	in   string
-	want bool
-}
-
-func TestDetectCapitalUse(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "USA",
-			want: true,
-		},
-		{
-			in:   "leetcode",
-			want: true,
-		},
-		{
-			in:   "Google",
-			want: true,
-		},
-		{
-			in:   "FlaG",
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := detectCapitalUse(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/detect-cycles-in-2d-grid/README.md b/problems/detect-cycles-in-2d-grid/README.md
deleted file mode 100644
index da2157e5e..000000000
--- a/problems/detect-cycles-in-2d-grid/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-numbers-of-function-calls-to-make-target-array "Minimum Numbers of Function Calls to Make Target Array")
-　　　　　　　　　　　　　　　　
-[Next >](../most-visited-sector-in-a-circular-track "Most Visited Sector in  a Circular Track")
-
-## [1559. Detect Cycles in 2D Grid (Medium)](https://leetcode.com/problems/detect-cycles-in-2d-grid "二维网格图中探测环")
-
-<p>Given a 2D array of characters <code>grid</code> of size <code>m x n</code>, you need to find if there exists any cycle consisting of the <strong>same value</strong> in <code>grid</code>.</p>
-
-<p>A cycle is a path of <strong>length 4 or more</strong> in the grid that starts and ends at the same cell. From a given cell, you can move to one of the cells adjacent to it - in one of the four directions (up, down, left, or right), if it has the <strong>same value</strong> of the current cell.</p>
-
-<p>Also, you cannot move to the cell that you visited in your last move. For example, the cycle <code>(1, 1) -&gt; (1, 2) -&gt; (1, 1)</code> is invalid because from <code>(1, 2)</code> we visited <code>(1, 1)</code> which was the last visited cell.</p>
-
-<p>Return <code>true</code> if any cycle of the same value exists in <code>grid</code>, otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/1.png" style="width: 231px; height: 152px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[&quot;a&quot;,&quot;a&quot;,&quot;a&quot;,&quot;a&quot;],[&quot;a&quot;,&quot;b&quot;,&quot;b&quot;,&quot;a&quot;],[&quot;a&quot;,&quot;b&quot;,&quot;b&quot;,&quot;a&quot;],[&quot;a&quot;,&quot;a&quot;,&quot;a&quot;,&quot;a&quot;]]
-<strong>Output:</strong> true
-<strong>Explanation: </strong>There are two valid cycles shown in different colors in the image below:
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/11.png" style="width: 225px; height: 163px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/22.png" style="width: 236px; height: 154px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[&quot;c&quot;,&quot;c&quot;,&quot;c&quot;,&quot;a&quot;],[&quot;c&quot;,&quot;d&quot;,&quot;c&quot;,&quot;c&quot;],[&quot;c&quot;,&quot;c&quot;,&quot;e&quot;,&quot;c&quot;],[&quot;f&quot;,&quot;c&quot;,&quot;c&quot;,&quot;c&quot;]]
-<strong>Output:</strong> true
-<strong>Explanation: </strong>There is only one valid cycle highlighted in the image below:
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/2.png" style="width: 229px; height: 157px;" />
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/3.png" style="width: 183px; height: 120px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[&quot;a&quot;,&quot;b&quot;,&quot;b&quot;],[&quot;b&quot;,&quot;z&quot;,&quot;b&quot;],[&quot;b&quot;,&quot;b&quot;,&quot;a&quot;]]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 500</code></li>
-	<li><code>grid</code> consists only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep track of the parent (previous position) to avoid considering an invalid path.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use DFS or BFS and keep track of visited cells to see if there is a cycle.
-</details>
diff --git a/problems/detect-pattern-of-length-m-repeated-k-or-more-times/README.md b/problems/detect-pattern-of-length-m-repeated-k-or-more-times/README.md
deleted file mode 100644
index 6f2fcdace..000000000
--- a/problems/detect-pattern-of-length-m-repeated-k-or-more-times/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-orders-and-customers-per-month "Unique Orders and Customers Per Month")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-length-of-subarray-with-positive-product "Maximum Length of Subarray With Positive Product")
-
-## [1566. Detect Pattern of Length M Repeated K or More Times (Easy)](https://leetcode.com/problems/detect-pattern-of-length-m-repeated-k-or-more-times "重复至少 K 次且长度为 M 的模式")
-
-<p>Given an array of positive integers <code>arr</code>, find a pattern of length <code>m</code> that is repeated <code>k</code> or more times.</p>
-
-<p>A <strong>pattern</strong> is a subarray (consecutive sub-sequence) that consists of one or more values, repeated multiple times <strong>consecutively </strong>without overlapping. A pattern is defined by its length and the number of repetitions.</p>
-
-<p>Return <code>true</code> <em>if there exists a pattern of length</em> <code>m</code> <em>that is repeated</em> <code>k</code> <em>or more times, otherwise return</em> <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,4,4,4,4], m = 1, k = 3
-<strong>Output:</strong> true
-<strong>Explanation: </strong>The pattern <strong>(4)</strong> of length 1 is repeated 4 consecutive times. Notice that pattern can be repeated k or more times but not less.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,1,2,1,1,1,3], m = 2, k = 2
-<strong>Output:</strong> true
-<strong>Explanation: </strong>The pattern <strong>(1,2)</strong> of length 2 is repeated 2 consecutive times. Another valid pattern <strong>(2,1) is</strong> also repeated 2 times.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,1,2,1,3], m = 2, k = 3
-<strong>Output:</strong> false
-<strong>Explanation: </strong>The pattern (1,2) is of length 2 but is repeated only 2 times. There is no pattern of length 2 that is repeated 3 or more times.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr.length &lt;= 100</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 100</code></li>
-	<li><code>1 &lt;= m &lt;= 100</code></li>
-	<li><code>2 &lt;= k &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Similar Questions
-  1. [Maximum Repeating Substring](../maximum-repeating-substring) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a three-layer loop to check all possible patterns by iterating through all possible starting positions, all indexes less than m, and if the character at the index is repeated k times.
-</details>
diff --git a/problems/detect-squares/README.md b/problems/detect-squares/README.md
deleted file mode 100644
index 982fcb70c..000000000
--- a/problems/detect-squares/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-beauty-in-the-array "Sum of Beauty in the Array")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-subsequence-repeated-k-times "Longest Subsequence Repeated k Times")
-
-## [2013. Detect Squares (Medium)](https://leetcode.com/problems/detect-squares "检测正方形")
-
-<p>You are given a stream of points on the X-Y plane. Design an algorithm that:</p>
-
-<ul>
-	<li><strong>Adds</strong> new points from the stream into a data structure. <strong>Duplicate</strong> points are allowed and should be treated as different points.</li>
-	<li>Given a query point, <strong>counts</strong> the number of ways to choose three points from the data structure such that the three points and the query point form an <strong>axis-aligned square</strong> with <strong>positive area</strong>.</li>
-</ul>
-
-<p>An <strong>axis-aligned square</strong> is a square whose edges are all the same length and are either parallel or perpendicular to the x-axis and y-axis.</p>
-
-<p>Implement the <code>DetectSquares</code> class:</p>
-
-<ul>
-	<li><code>DetectSquares()</code> Initializes the object with an empty data structure.</li>
-	<li><code>void add(int[] point)</code> Adds a new point <code>point = [x, y]</code> to the data structure.</li>
-	<li><code>int count(int[] point)</code> Counts the number of ways to form <strong>axis-aligned squares</strong> with point <code>point = [x, y]</code> as described above.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/01/image.png" style="width: 869px; height: 504px;" />
-<pre>
-<strong>Input</strong>
-[&quot;DetectSquares&quot;, &quot;add&quot;, &quot;add&quot;, &quot;add&quot;, &quot;count&quot;, &quot;count&quot;, &quot;add&quot;, &quot;count&quot;]
-[[], [[3, 10]], [[11, 2]], [[3, 2]], [[11, 10]], [[14, 8]], [[11, 2]], [[11, 10]]]
-<strong>Output</strong>
-[null, null, null, null, 1, 0, null, 2]
-
-<strong>Explanation</strong>
-DetectSquares detectSquares = new DetectSquares();
-detectSquares.add([3, 10]);
-detectSquares.add([11, 2]);
-detectSquares.add([3, 2]);
-detectSquares.count([11, 10]); // return 1. You can choose:
-                               //   - The first, second, and third points
-detectSquares.count([14, 8]);  // return 0. The query point cannot form a square with any points in the data structure.
-detectSquares.add([11, 2]);    // Adding duplicate points is allowed.
-detectSquares.count([11, 10]); // return 2. You can choose:
-                               //   - The first, second, and third points
-                               //   - The first, third, and fourth points
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>point.length == 2</code></li>
-	<li><code>0 &lt;= x, y &lt;= 1000</code></li>
-	<li>At most <code>3000</code> calls <strong>in total</strong> will be made to <code>add</code> and <code>count</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Maintain the frequency of all the points in a hash map.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Traverse the hash map and if any point has the same y-coordinate as the query point, consider this point and the query point to form one of the horizontal lines of the square.
-</details>
diff --git a/problems/determine-color-of-a-chessboard-square/README.md b/problems/determine-color-of-a-chessboard-square/README.md
deleted file mode 100644
index defbbb33c..000000000
--- a/problems/determine-color-of-a-chessboard-square/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-interview-candidates "Find Interview Candidates")
-　　　　　　　　　　　　　　　　
-[Next >](../sentence-similarity-iii "Sentence Similarity III")
-
-## [1812. Determine Color of a Chessboard Square (Easy)](https://leetcode.com/problems/determine-color-of-a-chessboard-square "判断国际象棋棋盘中一个格子的颜色")
-
-<p>You are given <code>coordinates</code>, a string that represents the coordinates of a square of the chessboard. Below is a chessboard for your reference.</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/screenshot-2021-02-20-at-22159-pm.png" style="width: 400px; height: 396px;" /></p>
-
-<p>Return <code>true</code><em> if the square is white, and </em><code>false</code><em> if the square is black</em>.</p>
-
-<p>The coordinate will always represent a valid chessboard square. The coordinate will always have the letter first, and the number second.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> coordinates = &quot;a1&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> From the chessboard above, the square with coordinates &quot;a1&quot; is black, so return false.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> coordinates = &quot;h3&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> From the chessboard above, the square with coordinates &quot;h3&quot; is white, so return true.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> coordinates = &quot;c7&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>coordinates.length == 2</code></li>
-	<li><code>&#39;a&#39; &lt;= coordinates[0] &lt;= &#39;h&#39;</code></li>
-	<li><code>&#39;1&#39; &lt;= coordinates[1] &lt;= &#39;8&#39;</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert the coordinates to (x, y) - that is, "a1" is (1, 1), "d7" is (4, 7).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try add the numbers together and look for a pattern.
-</details>
diff --git a/problems/determine-if-string-halves-are-alike/README.md b/problems/determine-if-string-halves-are-alike/README.md
deleted file mode 100644
index 8f0453b94..000000000
--- a/problems/determine-if-string-halves-are-alike/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-adjacent-swaps-for-k-consecutive-ones "Minimum Adjacent Swaps for K Consecutive Ones")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-eaten-apples "Maximum Number of Eaten Apples")
-
-## [1704. Determine if String Halves Are Alike (Easy)](https://leetcode.com/problems/determine-if-string-halves-are-alike "判断字符串的两半是否相似")
-
-<p>You are given a string <code>s</code> of even length. Split this string into two halves of equal lengths, and let <code>a</code> be the first half and <code>b</code> be the second half.</p>
-
-<p>Two strings are <strong>alike</strong> if they have the same number of vowels (<code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, <code>&#39;u&#39;</code>, <code>&#39;A&#39;</code>, <code>&#39;E&#39;</code>, <code>&#39;I&#39;</code>, <code>&#39;O&#39;</code>, <code>&#39;U&#39;</code>). Notice that <code>s</code> contains uppercase and lowercase letters.</p>
-
-<p>Return <code>true</code><em> if </em><code>a</code><em> and </em><code>b</code><em> are <strong>alike</strong></em>. Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;book&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> a = &quot;b<u>o</u>&quot; and b = &quot;<u>o</u>k&quot;. a has 1 vowel and b has 1 vowel. Therefore, they are alike.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;textbook&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> a = &quot;t<u>e</u>xt&quot; and b = &quot;b<u>oo</u>k&quot;. a has 1 vowel whereas b has 2. Therefore, they are not alike.
-Notice that the vowel o is counted twice.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s.length</code> is even.</li>
-	<li><code>s</code> consists of <strong>uppercase and lowercase</strong> letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create a function that checks if a character is a vowel, either uppercase or lowercase.
-</details>
diff --git a/problems/determine-if-two-strings-are-close/README.md b/problems/determine-if-two-strings-are-close/README.md
deleted file mode 100644
index a6740f403..000000000
--- a/problems/determine-if-two-strings-are-close/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-an-ordered-stream "Design an Ordered Stream")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-operations-to-reduce-x-to-zero "Minimum Operations to Reduce X to Zero")
-
-## [1657. Determine if Two Strings Are Close (Medium)](https://leetcode.com/problems/determine-if-two-strings-are-close "确定两个字符串是否接近")
-
-<p>Two strings are considered <strong>close</strong> if you can attain one from the other using the following operations:</p>
-
-<ul>
-	<li>Operation 1: Swap any two <strong>existing</strong> characters.
-	<ul>
-		<li>For example, <code>a<u>b</u>cd<u>e</u> -&gt; a<u>e</u>cd<u>b</u></code></li>
-	</ul>
-	</li>
-	<li>Operation 2: Transform <strong>every</strong> occurrence of one <strong>existing</strong> character into another <strong>existing</strong> character, and do the same with the other character.
-	<ul>
-		<li>For example, <code><u>aa</u>c<u>abb</u> -&gt; <u>bb</u>c<u>baa</u></code> (all <code>a</code>&#39;s turn into <code>b</code>&#39;s, and all <code>b</code>&#39;s turn into <code>a</code>&#39;s)</li>
-	</ul>
-	</li>
-</ul>
-
-<p>You can use the operations on either string as many times as necessary.</p>
-
-<p>Given two strings, <code>word1</code> and <code>word2</code>, return <code>true</code><em> if </em><code>word1</code><em> and </em><code>word2</code><em> are <strong>close</strong>, and </em><code>false</code><em> otherwise.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;abc&quot;, word2 = &quot;bca&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can attain word2 from word1 in 2 operations.
-Apply Operation 1: &quot;a<u>bc</u>&quot; -&gt; &quot;a<u>cb</u>&quot;
-Apply Operation 1: &quot;<u>a</u>c<u>b</u>&quot; -&gt; &quot;<u>b</u>c<u>a</u>&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;a&quot;, word2 = &quot;aa&quot;
-<strong>Output:</strong> false
-<strong>Explanation: </strong>It is impossible to attain word2 from word1, or vice versa, in any number of operations.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;cabbba&quot;, word2 = &quot;abbccc&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can attain word2 from word1 in 3 operations.
-Apply Operation 1: &quot;ca<u>b</u>bb<u>a</u>&quot; -&gt; &quot;ca<u>a</u>bb<u>b</u>&quot;
-<code>Apply Operation 2: &quot;</code><u>c</u>aa<u>bbb</u>&quot; -&gt; &quot;<u>b</u>aa<u>ccc</u>&quot;
-Apply Operation 2: &quot;<u>baa</u>ccc&quot; -&gt; &quot;<u>abb</u>ccc&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word1.length, word2.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>word1</code> and <code>word2</code> contain&nbsp;only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Operation 1 allows you to freely reorder the string.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Operation 2 allows you to freely reassign the letters' frequencies.
-</details>
diff --git a/problems/determine-whether-matrix-can-be-obtained-by-rotation/README.md b/problems/determine-whether-matrix-can-be-obtained-by-rotation/README.md
deleted file mode 100644
index dc07d77be..000000000
--- a/problems/determine-whether-matrix-can-be-obtained-by-rotation/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-pairs-in-two-arrays "Count Pairs in Two Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../reduction-operations-to-make-the-array-elements-equal "Reduction Operations to Make the Array Elements Equal")
-
-## [1886. Determine Whether Matrix Can Be Obtained By Rotation (Easy)](https://leetcode.com/problems/determine-whether-matrix-can-be-obtained-by-rotation "判断矩阵经轮转后是否一致")
-
-<p>Given two <code>n x n</code> binary matrices <code>mat</code> and <code>target</code>, return <code>true</code><em> if it is possible to make </em><code>mat</code><em> equal to </em><code>target</code><em> by <strong>rotating</strong> </em><code>mat</code><em> in <strong>90-degree increments</strong>, or </em><code>false</code><em> otherwise.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/20/grid3.png" style="width: 301px; height: 121px;" />
-<pre>
-<strong>Input:</strong> mat = [[0,1],[1,0]], target = [[1,0],[0,1]]
-<strong>Output:</strong> true
-<strong>Explanation: </strong>We can rotate mat 90 degrees clockwise to make mat equal target.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/20/grid4.png" style="width: 301px; height: 121px;" />
-<pre>
-<strong>Input:</strong> mat = [[0,1],[1,1]], target = [[1,0],[0,1]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to make mat equal to target by rotating mat.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/26/grid4.png" style="width: 661px; height: 184px;" />
-<pre>
-<strong>Input:</strong> mat = [[0,0,0],[0,1,0],[1,1,1]], target = [[1,1,1],[0,1,0],[0,0,0]]
-<strong>Output:</strong> true
-<strong>Explanation: </strong>We can rotate mat 90 degrees clockwise two times to make mat equal target.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == mat.length == target.length</code></li>
-	<li><code>n == mat[i].length == target[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 10</code></li>
-	<li><code>mat[i][j]</code> and <code>target[i][j]</code> are either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Rotate Image](../rotate-image) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What is the maximum number of rotations you have to check?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is there a formula you can use to rotate a matrix 90 degrees?
-</details>
diff --git a/problems/detonate-the-maximum-bombs/README.md b/problems/detonate-the-maximum-bombs/README.md
deleted file mode 100644
index 2a7ecfe4b..000000000
--- a/problems/detonate-the-maximum-bombs/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-good-days-to-rob-the-bank "Find Good Days to Rob the Bank")
-　　　　　　　　　　　　　　　　
-[Next >](../sequentially-ordinal-rank-tracker "Sequentially Ordinal Rank Tracker")
-
-## [2101. Detonate the Maximum Bombs (Medium)](https://leetcode.com/problems/detonate-the-maximum-bombs "引爆最多的炸弹")
-
-<p>You are given a list of bombs. The <strong>range</strong> of a bomb is defined as the area where its effect can be felt. This area is in the shape of a <strong>circle</strong> with the center as the location of the bomb.</p>
-
-<p>The bombs are represented by a <strong>0-indexed</strong> 2D integer array <code>bombs</code> where <code>bombs[i] = [x<sub>i</sub>, y<sub>i</sub>, r<sub>i</sub>]</code>. <code>x<sub>i</sub></code> and <code>y<sub>i</sub></code> denote the X-coordinate and Y-coordinate of the location of the <code>i<sup>th</sup></code> bomb, whereas <code>r<sub>i</sub></code> denotes the <strong>radius</strong> of its range.</p>
-
-<p>You may choose to detonate a <strong>single</strong> bomb. When a bomb is detonated, it will detonate <strong>all bombs</strong> that lie in its range. These bombs will further detonate the bombs that lie in their ranges.</p>
-
-<p>Given the list of <code>bombs</code>, return <em>the <strong>maximum</strong> number of bombs that can be detonated if you are allowed to detonate <strong>only one</strong> bomb</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/06/desmos-eg-3.png" style="width: 300px; height: 300px;" />
-<pre>
-<strong>Input:</strong> bombs = [[2,1,3],[6,1,4]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-The above figure shows the positions and ranges of the 2 bombs.
-If we detonate the left bomb, the right bomb will not be affected.
-But if we detonate the right bomb, both bombs will be detonated.
-So the maximum bombs that can be detonated is max(1, 2) = 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/06/desmos-eg-2.png" style="width: 300px; height: 300px;" />
-<pre>
-<strong>Input:</strong> bombs = [[1,1,5],[10,10,5]]
-<strong>Output:</strong> 1
-<strong>Explanation:
-</strong>Detonating either bomb will not detonate the other bomb, so the maximum number of bombs that can be detonated is 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/07/desmos-eg1.png" style="width: 300px; height: 300px;" />
-<pre>
-<strong>Input:</strong> bombs = [[1,2,3],[2,3,1],[3,4,2],[4,5,3],[5,6,4]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong>
-The best bomb to detonate is bomb 0 because:
-- Bomb 0 detonates bombs 1 and 2. The red circle denotes the range of bomb 0.
-- Bomb 2 detonates bomb 3. The blue circle denotes the range of bomb 2.
-- Bomb 3 detonates bomb 4. The green circle denotes the range of bomb 3.
-Thus all 5 bombs are detonated.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= bombs.length&nbsp;&lt;= 100</code></li>
-	<li><code>bombs[i].length == 3</code></li>
-	<li><code>1 &lt;= x<sub>i</sub>, y<sub>i</sub>, r<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can we model the relationship between different bombs? Can "graphs" help us?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Bombs are nodes and are connected to other bombs in their range by directed edges.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If we know which bombs will be affected when any bomb is detonated, how can we find the total number of bombs that will be detonated if we start from a fixed bomb?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Run a Depth First Search (DFS) from every node, and all the nodes it reaches are the bombs that will be detonated.
-</details>
diff --git a/problems/di-string-match/README.md b/problems/di-string-match/README.md
deleted file mode 100644
index 178ccec19..000000000
--- a/problems/di-string-match/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-mountain-array "Valid Mountain Array")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-shortest-superstring "Find the Shortest Superstring")
-
-## [942. DI String Match (Easy)](https://leetcode.com/problems/di-string-match "增减字符串匹配")
-
-<p>A permutation <code>perm</code> of <code>n + 1</code> integers of all the integers in the range <code>[0, n]</code> can be represented as a string <code>s</code> of length <code>n</code> where:</p>
-
-<ul>
-	<li><code>s[i] == &#39;I&#39;</code> if <code>perm[i] &lt; perm[i + 1]</code>, and</li>
-	<li><code>s[i] == &#39;D&#39;</code> if <code>perm[i] &gt; perm[i + 1]</code>.</li>
-</ul>
-
-<p>Given a string <code>s</code>, reconstruct the permutation <code>perm</code> and return it. If there are multiple valid permutations perm, return <strong>any of them</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "IDID"
-<strong>Output:</strong> [0,4,1,3,2]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "III"
-<strong>Output:</strong> [0,1,2,3]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s = "DDI"
-<strong>Output:</strong> [3,2,0,1]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;I&#39;</code> or <code>&#39;D&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/di-string-match/di_string_match.go b/problems/di-string-match/di_string_match.go
deleted file mode 100644
index ad11a901c..000000000
--- a/problems/di-string-match/di_string_match.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem942
-
-func diStringMatch(S string) []int {
-	lo, hi := 0, len(S)
-	ans := make([]int, hi, hi+1)
-	for i, v := range S {
-		if v == 'I' {
-			ans[i] = lo
-			lo++
-		} else {
-			ans[i] = hi
-			hi--
-		}
-	}
-	return append(ans, lo)
-}
diff --git a/problems/di-string-match/di_string_match_test.go b/problems/di-string-match/di_string_match_test.go
deleted file mode 100644
index ef44d3764..000000000
--- a/problems/di-string-match/di_string_match_test.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package problem942
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   string
-	want []int
-}
-
-func TestDiStringMatch(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "IDID",
-			want: []int{0, 4, 1, 3, 2},
-		},
-		{
-			in:   "III",
-			want: []int{0, 1, 2, 3},
-		},
-		{
-			in:   "DDI",
-			want: []int{3, 2, 0, 1},
-		},
-	}
-	for _, tt := range tests {
-		got := diStringMatch(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/diagonal-traverse-ii/README.md b/problems/diagonal-traverse-ii/README.md
deleted file mode 100644
index f0f505c37..000000000
--- a/problems/diagonal-traverse-ii/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-points-you-can-obtain-from-cards "Maximum Points You Can Obtain from Cards")
-　　　　　　　　　　　　　　　　
-[Next >](../constrained-subsequence-sum "Constrained Subsequence Sum")
-
-## [1424. Diagonal Traverse II (Medium)](https://leetcode.com/problems/diagonal-traverse-ii "对角线遍历 II")
-
-<p>Given a 2D integer array <code>nums</code>, return <em>all elements of </em><code>nums</code><em> in diagonal order as shown in the below images</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/04/08/sample_1_1784.png" style="width: 158px; height: 143px;" />
-<pre>
-<strong>Input:</strong> nums = [[1,2,3],[4,5,6],[7,8,9]]
-<strong>Output:</strong> [1,4,2,7,5,3,8,6,9]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/04/08/sample_2_1784.png" style="width: 230px; height: 177px;" />
-<pre>
-<strong>Input:</strong> nums = [[1,2,3,4,5],[6,7],[8],[9,10,11],[12,13,14,15,16]]
-<strong>Output:</strong> [1,6,2,8,7,3,9,4,12,10,5,13,11,14,15,16]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i].length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= sum(nums[i].length) &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i][j] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Notice that numbers with equal sums of row and column indexes belong to the same diagonal.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Store them in tuples (sum, row, val), sort them, and then regroup the answer.
-</details>
diff --git a/problems/diagonal-traverse/README.md b/problems/diagonal-traverse/README.md
deleted file mode 100644
index 54d674860..000000000
--- a/problems/diagonal-traverse/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../random-point-in-non-overlapping-rectangles "Random Point in Non-overlapping Rectangles")
-　　　　　　　　　　　　　　　　
-[Next >](../the-maze-iii "The Maze III")
-
-## [498. Diagonal Traverse (Medium)](https://leetcode.com/problems/diagonal-traverse "对角线遍历")
-
-<p>Given an <code>m x n</code> matrix <code>mat</code>, return <em>an array of all the elements of the array in a diagonal order</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/10/diag1-grid.jpg" style="width: 334px; height: 334px;" />
-<pre>
-<strong>Input:</strong> mat = [[1,2,3],[4,5,6],[7,8,9]]
-<strong>Output:</strong> [1,2,4,7,5,3,6,8,9]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[1,2],[3,4]]
-<strong>Output:</strong> [1,2,3,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= m * n &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= mat[i][j] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Decode the Slanted Ciphertext](../decode-the-slanted-ciphertext) (Medium)
diff --git a/problems/diagonal-traverse/diagonal_traverse.go b/problems/diagonal-traverse/diagonal_traverse.go
deleted file mode 100644
index f9eeb3d8b..000000000
--- a/problems/diagonal-traverse/diagonal_traverse.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem498
diff --git a/problems/diagonal-traverse/diagonal_traverse_test.go b/problems/diagonal-traverse/diagonal_traverse_test.go
deleted file mode 100644
index f9eeb3d8b..000000000
--- a/problems/diagonal-traverse/diagonal_traverse_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem498
diff --git a/problems/diameter-of-binary-tree/README.md b/problems/diameter-of-binary-tree/README.md
deleted file mode 100644
index afe2198fb..000000000
--- a/problems/diameter-of-binary-tree/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../01-matrix "01 Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../output-contest-matches "Output Contest Matches")
-
-## [543. Diameter of Binary Tree (Easy)](https://leetcode.com/problems/diameter-of-binary-tree "二叉树的直径")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the length of the <strong>diameter</strong> of the tree</em>.</p>
-
-<p>The <strong>diameter</strong> of a binary tree is the <strong>length</strong> of the longest path between any two nodes in a tree. This path may or may not pass through the <code>root</code>.</p>
-
-<p>The <strong>length</strong> of a path between two nodes is represented by the number of edges between them.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/06/diamtree.jpg" style="width: 292px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 3 is the length of the path [4,2,1,3] or [5,2,1,3].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,2]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Diameter of N-Ary Tree](../diameter-of-n-ary-tree) (Medium)
diff --git a/problems/diameter-of-binary-tree/diameter_of_binary_tree.go b/problems/diameter-of-binary-tree/diameter_of_binary_tree.go
deleted file mode 100644
index 837e867e5..000000000
--- a/problems/diameter-of-binary-tree/diameter_of_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem543
diff --git a/problems/diameter-of-binary-tree/diameter_of_binary_tree_test.go b/problems/diameter-of-binary-tree/diameter_of_binary_tree_test.go
deleted file mode 100644
index 837e867e5..000000000
--- a/problems/diameter-of-binary-tree/diameter_of_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem543
diff --git a/problems/diameter-of-n-ary-tree/README.md b/problems/diameter-of-n-ary-tree/README.md
deleted file mode 100644
index 23080aa67..000000000
--- a/problems/diameter-of-n-ary-tree/README.md
+++ /dev/null
@@ -1,32 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-a-value-of-a-mysterious-function-closest-to-target "Find a Value of a Mysterious Function Closest to Target")
-　　　　　　　　　　　　　　　　
-[Next >](../count-odd-numbers-in-an-interval-range "Count Odd Numbers in an Interval Range")
-
-## [1522. Diameter of N-Ary Tree (Medium)](https://leetcode.com/problems/diameter-of-n-ary-tree "N 叉树的直径")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-
-### Similar Questions
-  1. [Diameter of Binary Tree](../diameter-of-binary-tree) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For the node i, calculate the height of each of its children and keep the first and second maximum heights (max1_i , max2_i).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check all nodes and return max( 2 + max1_i  +  max2_i ).
-</details>
diff --git a/problems/dice-roll-simulation/README.md b/problems/dice-roll-simulation/README.md
deleted file mode 100644
index 5bcd14155..000000000
--- a/problems/dice-roll-simulation/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../queens-that-can-attack-the-king "Queens That Can Attack the King")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-equal-frequency "Maximum Equal Frequency")
-
-## [1223. Dice Roll Simulation (Hard)](https://leetcode.com/problems/dice-roll-simulation "掷骰子模拟")
-
-<p>A die simulator generates a random number from <code>1</code> to <code>6</code> for each roll. You introduced a constraint to the generator such that it cannot roll the number <code>i</code> more than <code>rollMax[i]</code> (<strong>1-indexed</strong>) consecutive times.</p>
-
-<p>Given an array of integers <code>rollMax</code> and an integer <code>n</code>, return <em>the number of distinct sequences that can be obtained with exact </em><code>n</code><em> rolls</em>. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>Two sequences are considered different if at least one element differs from each other.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, rollMax = [1,1,2,2,2,3]
-<strong>Output:</strong> 34
-<strong>Explanation:</strong> There will be 2 rolls of die, if there are no constraints on the die, there are 6 * 6 = 36 possible combinations. In this case, looking at rollMax array, the numbers 1 and 2 appear at most once consecutively, therefore sequences (1,1) and (2,2) cannot occur, so the final answer is 36-2 = 34.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, rollMax = [1,1,1,1,1,1]
-<strong>Output:</strong> 30
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, rollMax = [1,1,1,2,2,3]
-<strong>Output:</strong> 181
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 5000</code></li>
-	<li><code>rollMax.length == 6</code></li>
-	<li><code>1 &lt;= rollMax[i] &lt;= 15</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Find Missing Observations](../find-missing-observations) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think on Dynamic Programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-DP(pos, last) which means we are at the position pos having as last the last character seen.
-</details>
diff --git a/problems/diet-plan-performance/README.md b/problems/diet-plan-performance/README.md
deleted file mode 100644
index 8a830f600..000000000
--- a/problems/diet-plan-performance/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../prime-arrangements "Prime Arrangements")
-　　　　　　　　　　　　　　　　
-[Next >](../can-make-palindrome-from-substring "Can Make Palindrome from Substring")
-
-## [1176. Diet Plan Performance (Easy)](https://leetcode.com/problems/diet-plan-performance "健身计划评估")
-
-<p>A dieter consumes&nbsp;<code>calories[i]</code>&nbsp;calories on the <code>i</code>-th day.&nbsp; For every consecutive sequence of <code>k</code> days, they look at <em>T</em>, the total calories consumed during that sequence of <code>k</code> days:</p>
-
-<ul>
-	<li>If <code>T &lt; lower</code>, they performed poorly on their diet and lose 1 point;&nbsp;</li>
-	<li>If <code>T &gt; upper</code>, they performed well on their diet and gain 1 point;</li>
-	<li>Otherwise, they performed normally and there is no change in points.</li>
-</ul>
-
-<p>Return the total number of points the dieter has after all <code>calories.length</code>&nbsp;days.</p>
-
-<p>Note that: The total points could be negative.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> calories = [1,2,3,4,5], k = 1, lower = 3, upper = 3
-<strong>Output:</strong> 0
-<strong>Explaination</strong>: calories[0], calories[1] &lt; lower and calories[3], calories[4] &gt; upper, total points = 0.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> calories = [3,2], k = 2, lower = 0, upper = 1
-<strong>Output:</strong> 1
-<strong>Explaination</strong>: calories[0] + calories[1] &gt; upper, total points = 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> calories = [6,5,0,0], k = 2, lower = 1, upper = 5
-<strong>Output:</strong> 0
-<strong>Explaination</strong>: calories[0] + calories[1] &gt; upper, lower &lt;= calories[1] + calories[2] &lt;= upper, calories[2] + calories[3] &lt; lower, total points = 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= calories.length &lt;= 10^5</code></li>
-	<li><code>0 &lt;= calories[i] &lt;= 20000</code></li>
-	<li><code>0 &lt;= lower &lt;= upper</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use sliding window technique (aka two pointers).
-</details>
diff --git a/problems/different-ways-to-add-parentheses/README.md b/problems/different-ways-to-add-parentheses/README.md
deleted file mode 100644
index 7846b8a73..000000000
--- a/problems/different-ways-to-add-parentheses/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../search-a-2d-matrix-ii "Search a 2D Matrix II")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-anagram "Valid Anagram")
-
-## [241. Different Ways to Add Parentheses (Medium)](https://leetcode.com/problems/different-ways-to-add-parentheses "为运算表达式设计优先级")
-
-<p>Given a string <code>expression</code> of numbers and operators, return <em>all possible results from computing all the different possible ways to group numbers and operators</em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;2-1-1&quot;
-<strong>Output:</strong> [0,2]
-<strong>Explanation:</strong>
-((2-1)-1) = 0 
-(2-(1-1)) = 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;2*3-4*5&quot;
-<strong>Output:</strong> [-34,-14,-10,-10,10]
-<strong>Explanation:</strong>
-(2*(3-(4*5))) = -34 
-((2*3)-(4*5)) = -14 
-((2*(3-4))*5) = -10 
-(2*((3-4)*5)) = -10 
-(((2*3)-4)*5) = 10
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= expression.length &lt;= 20</code></li>
-	<li><code>expression</code> consists of digits and the operator <code>&#39;+&#39;</code>, <code>&#39;-&#39;</code>, and <code>&#39;*&#39;</code>.</li>
-	<li>All the integer values in the input expression are in the range <code>[0, 99]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Unique Binary Search Trees II](../unique-binary-search-trees-ii) (Medium)
-  1. [Basic Calculator](../basic-calculator) (Hard)
-  1. [Expression Add Operators](../expression-add-operators) (Hard)
diff --git a/problems/different-ways-to-add-parentheses/different_ways_to_add_parentheses.go b/problems/different-ways-to-add-parentheses/different_ways_to_add_parentheses.go
deleted file mode 100644
index f00d72021..000000000
--- a/problems/different-ways-to-add-parentheses/different_ways_to_add_parentheses.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem241
diff --git a/problems/different-ways-to-add-parentheses/different_ways_to_add_parentheses_test.go b/problems/different-ways-to-add-parentheses/different_ways_to_add_parentheses_test.go
deleted file mode 100644
index f00d72021..000000000
--- a/problems/different-ways-to-add-parentheses/different_ways_to_add_parentheses_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem241
diff --git a/problems/digit-count-in-range/README.md b/problems/digit-count-in-range/README.md
deleted file mode 100644
index 144467f1b..000000000
--- a/problems/digit-count-in-range/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../campus-bikes-ii "Campus Bikes II")
-　　　　　　　　　　　　　　　　
-[Next >](../product-sales-analysis-i "Product Sales Analysis I")
-
-## [1067. Digit Count in Range (Hard)](https://leetcode.com/problems/digit-count-in-range "范围内的数字计数")
-
-Given an integer <code>d</code> between <code>0</code> and <code>9</code>, and two positive integers <code>low</code> and <code>high</code> as lower and upper bounds, respectively. Return the number of times that <code>d</code> occurs as a digit in all integers between <code>low</code> and <code>high</code>, including the bounds <code>low</code> and <code>high</code>.
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>d = <span id="example-input-1-1">1</span>, low = <span id="example-input-1-2">1</span>, high = <span id="example-input-1-3">13</span>
-<strong>Output: </strong><span id="example-output-1">6</span>
-<strong>Explanation: </strong>
-The digit <code>d=1</code> occurs <code>6</code> times in <code>1,10,11,12,13</code>. Note that the digit <code>d=1</code> occurs twice in the number <code>11</code>.
-</pre>
-
-<div>
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>d = <span id="example-input-2-1">3</span>, low = <span id="example-input-2-2">100</span>, high = <span id="example-input-2-3">250</span>
-<strong>Output: </strong><span id="example-output-2">35</span>
-<strong>Explanation: </strong>
-The digit <code>d=3</code> occurs <code>35</code> times in <code>103,113,123,130,131,...,238,239,243</code>.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>0 &lt;= d &lt;= 9</code></li>
-	<li><code>1 &lt;= low &lt;= high &lt;= 2&times;10^8</code></li>
-</ol>
-</div>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Number of Digit One](../number-of-digit-one) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Define a function f(x) to get the requested sum from 1 to x. So the answer will be f(hi) - f(lo - 1)
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In order to solve f(x) we need to do a DP over digits approach.
-</details>
diff --git a/problems/dinner-plate-stacks/README.md b/problems/dinner-plate-stacks/README.md
deleted file mode 100644
index 3536498dd..000000000
--- a/problems/dinner-plate-stacks/README.md
+++ /dev/null
@@ -1,95 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-zero-sum-consecutive-nodes-from-linked-list "Remove Zero Sum Consecutive Nodes from Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../immediate-food-delivery-i "Immediate Food Delivery I")
-
-## [1172. Dinner Plate Stacks (Hard)](https://leetcode.com/problems/dinner-plate-stacks "餐盘栈")
-
-<p>You have an infinite number of stacks arranged in a row and numbered (left to right) from <code>0</code>, each of the stacks has the same maximum capacity.</p>
-
-<p>Implement the <code>DinnerPlates</code> class:</p>
-
-<ul>
-	<li><code>DinnerPlates(int capacity)</code> Initializes the object with the maximum capacity of the stacks <code>capacity</code>.</li>
-	<li><code>void push(int val)</code> Pushes the given integer <code>val</code> into the leftmost stack with a size less than <code>capacity</code>.</li>
-	<li><code>int pop()</code> Returns the value at the top of the rightmost non-empty stack and removes it from that stack, and returns <code>-1</code> if all the stacks are empty.</li>
-	<li><code>int popAtStack(int index)</code> Returns the value at the top of the stack with the given index <code>index</code> and removes it from that stack or returns <code>-1</code> if the stack with that given index is empty.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;DinnerPlates&quot;, &quot;push&quot;, &quot;push&quot;, &quot;push&quot;, &quot;push&quot;, &quot;push&quot;, &quot;popAtStack&quot;, &quot;push&quot;, &quot;push&quot;, &quot;popAtStack&quot;, &quot;popAtStack&quot;, &quot;pop&quot;, &quot;pop&quot;, &quot;pop&quot;, &quot;pop&quot;, &quot;pop&quot;]
-[[2], [1], [2], [3], [4], [5], [0], [20], [21], [0], [2], [], [], [], [], []]
-<strong>Output</strong>
-[null, null, null, null, null, null, 2, null, null, 20, 21, 5, 4, 3, 1, -1]
-
-<strong>Explanation:</strong> 
-DinnerPlates D = DinnerPlates(2);  // Initialize with capacity = 2
-D.push(1);
-D.push(2);
-D.push(3);
-D.push(4);
-D.push(5);         // The stacks are now:  2  4
-                                           1  3  5
-                                           ﹈ ﹈ ﹈
-D.popAtStack(0);   // Returns 2.  The stacks are now:     4
-                                                       1  3  5
-                                                       ﹈ ﹈ ﹈
-D.push(20);        // The stacks are now: 20  4
-                                           1  3  5
-                                           ﹈ ﹈ ﹈
-D.push(21);        // The stacks are now: 20  4 21
-                                           1  3  5
-                                           ﹈ ﹈ ﹈
-D.popAtStack(0);   // Returns 20.  The stacks are now:     4 21
-                                                        1  3  5
-                                                        ﹈ ﹈ ﹈
-D.popAtStack(2);   // Returns 21.  The stacks are now:     4
-                                                        1  3  5
-                                                        ﹈ ﹈ ﹈ 
-D.pop()            // Returns 5.  The stacks are now:      4
-                                                        1  3 
-                                                        ﹈ ﹈  
-D.pop()            // Returns 4.  The stacks are now:   1  3 
-                                                        ﹈ ﹈   
-D.pop()            // Returns 3.  The stacks are now:   1 
-                                                        ﹈   
-D.pop()            // Returns 1.  There are no stacks.
-D.pop()            // Returns -1.  There are still no stacks.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= capacity &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= val &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= index &lt;= 10<sup>5</sup></code></li>
-	<li>At most <code>2 * 10<sup>5</sup></code> calls will be made to <code>push</code>, <code>pop</code>, and <code>popAtStack</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a data structure to save the plate status. You may need to operate the exact index. Maintain the leftmost vacant stack and the rightmost non-empty stack.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a list of stack to store the plate status. Use heap to maintain the leftmost and rightmost valid stack.
-</details>
diff --git a/problems/display-table-of-food-orders-in-a-restaurant/README.md b/problems/display-table-of-food-orders-in-a-restaurant/README.md
deleted file mode 100644
index 6ea038fe2..000000000
--- a/problems/display-table-of-food-orders-in-a-restaurant/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reformat-the-string "Reformat The String")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-frogs-croaking "Minimum Number of Frogs Croaking")
-
-## [1418. Display Table of Food Orders in a Restaurant (Medium)](https://leetcode.com/problems/display-table-of-food-orders-in-a-restaurant "点菜展示表")
-
-<p>Given&nbsp;the array <code>orders</code>, which represents the orders that customers have done in a restaurant. More specifically&nbsp;<code>orders[i]=[customerName<sub>i</sub>,tableNumber<sub>i</sub>,foodItem<sub>i</sub>]</code> where <code>customerName<sub>i</sub></code> is the name of the customer, <code>tableNumber<sub>i</sub></code>&nbsp;is the table customer sit at, and <code>foodItem<sub>i</sub></code>&nbsp;is the item customer orders.</p>
-
-<p><em>Return the restaurant&#39;s &ldquo;<strong>display table</strong>&rdquo;</em>. The &ldquo;<strong>display table</strong>&rdquo; is a table whose row entries denote how many of each food item each table ordered. The first column is the table number and the remaining columns correspond to each food item in alphabetical order. The first row should be a header whose first column is &ldquo;Table&rdquo;, followed by the names of the food items. Note that the customer names are not part of the table. Additionally, the rows should be sorted in numerically increasing order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> orders = [[&quot;David&quot;,&quot;3&quot;,&quot;Ceviche&quot;],[&quot;Corina&quot;,&quot;10&quot;,&quot;Beef Burrito&quot;],[&quot;David&quot;,&quot;3&quot;,&quot;Fried Chicken&quot;],[&quot;Carla&quot;,&quot;5&quot;,&quot;Water&quot;],[&quot;Carla&quot;,&quot;5&quot;,&quot;Ceviche&quot;],[&quot;Rous&quot;,&quot;3&quot;,&quot;Ceviche&quot;]]
-<strong>Output:</strong> [[&quot;Table&quot;,&quot;Beef Burrito&quot;,&quot;Ceviche&quot;,&quot;Fried Chicken&quot;,&quot;Water&quot;],[&quot;3&quot;,&quot;0&quot;,&quot;2&quot;,&quot;1&quot;,&quot;0&quot;],[&quot;5&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;,&quot;1&quot;],[&quot;10&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;]] 
-<strong>Explanation:
-</strong>The displaying table looks like:
-<strong>Table,Beef Burrito,Ceviche,Fried Chicken,Water</strong>
-3    ,0           ,2      ,1            ,0
-5    ,0           ,1      ,0            ,1
-10   ,1           ,0      ,0            ,0
-For the table 3: David orders &quot;Ceviche&quot; and &quot;Fried Chicken&quot;, and Rous orders &quot;Ceviche&quot;.
-For the table 5: Carla orders &quot;Water&quot; and &quot;Ceviche&quot;.
-For the table 10: Corina orders &quot;Beef Burrito&quot;. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> orders = [[&quot;James&quot;,&quot;12&quot;,&quot;Fried Chicken&quot;],[&quot;Ratesh&quot;,&quot;12&quot;,&quot;Fried Chicken&quot;],[&quot;Amadeus&quot;,&quot;12&quot;,&quot;Fried Chicken&quot;],[&quot;Adam&quot;,&quot;1&quot;,&quot;Canadian Waffles&quot;],[&quot;Brianna&quot;,&quot;1&quot;,&quot;Canadian Waffles&quot;]]
-<strong>Output:</strong> [[&quot;Table&quot;,&quot;Canadian Waffles&quot;,&quot;Fried Chicken&quot;],[&quot;1&quot;,&quot;2&quot;,&quot;0&quot;],[&quot;12&quot;,&quot;0&quot;,&quot;3&quot;]] 
-<strong>Explanation:</strong> 
-For the table 1: Adam and Brianna order &quot;Canadian Waffles&quot;.
-For the table 12: James, Ratesh and Amadeus order &quot;Fried Chicken&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> orders = [[&quot;Laura&quot;,&quot;2&quot;,&quot;Bean Burrito&quot;],[&quot;Jhon&quot;,&quot;2&quot;,&quot;Beef Burrito&quot;],[&quot;Melissa&quot;,&quot;2&quot;,&quot;Soda&quot;]]
-<strong>Output:</strong> [[&quot;Table&quot;,&quot;Bean Burrito&quot;,&quot;Beef Burrito&quot;,&quot;Soda&quot;],[&quot;2&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;orders.length &lt;= 5 * 10^4</code></li>
-	<li><code>orders[i].length == 3</code></li>
-	<li><code>1 &lt;= customerName<sub>i</sub>.length, foodItem<sub>i</sub>.length &lt;= 20</code></li>
-	<li><code>customerName<sub>i</sub></code> and <code>foodItem<sub>i</sub></code> consist of lowercase and uppercase English letters and the space character.</li>
-	<li><code>tableNumber<sub>i</sub>&nbsp;</code>is a valid integer between <code>1</code> and <code>500</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep the frequency of all pairs (tableNumber, foodItem) using a hashmap.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort rows by tableNumber and columns by foodItem, then process the resulted table.
-</details>
diff --git a/problems/distance-between-bus-stops/README.md b/problems/distance-between-bus-stops/README.md
deleted file mode 100644
index f94b2ff73..000000000
--- a/problems/distance-between-bus-stops/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-ones "Maximum Number of Ones")
-　　　　　　　　　　　　　　　　
-[Next >](../day-of-the-week "Day of the Week")
-
-## [1184. Distance Between Bus Stops (Easy)](https://leetcode.com/problems/distance-between-bus-stops "公交站间的距离")
-
-<p>A bus&nbsp;has <code>n</code> stops numbered from <code>0</code> to <code>n - 1</code> that form&nbsp;a circle. We know the distance between all pairs of neighboring stops where <code>distance[i]</code> is the distance between the stops number&nbsp;<code>i</code> and <code>(i + 1) % n</code>.</p>
-
-<p>The bus goes along both directions&nbsp;i.e. clockwise and counterclockwise.</p>
-
-<p>Return the shortest distance between the given&nbsp;<code>start</code>&nbsp;and <code>destination</code>&nbsp;stops.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/09/03/untitled-diagram-1.jpg" style="width: 388px; height: 240px;" /></p>
-
-<pre>
-<strong>Input:</strong> distance = [1,2,3,4], start = 0, destination = 1
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Distance between 0 and 1 is 1 or 9, minimum is 1.</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/09/03/untitled-diagram-1-1.jpg" style="width: 388px; height: 240px;" /></p>
-
-<pre>
-<strong>Input:</strong> distance = [1,2,3,4], start = 0, destination = 2
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Distance between 0 and 2 is 3 or 7, minimum is 3.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 3:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/09/03/untitled-diagram-1-2.jpg" style="width: 388px; height: 240px;" /></p>
-
-<pre>
-<strong>Input:</strong> distance = [1,2,3,4], start = 0, destination = 3
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Distance between 0 and 3 is 6 or 4, minimum is 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n&nbsp;&lt;= 10^4</code></li>
-	<li><code>distance.length == n</code></li>
-	<li><code>0 &lt;= start, destination &lt; n</code></li>
-	<li><code>0 &lt;= distance[i] &lt;= 10^4</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the distance between the two stops if the bus moved in clockwise or counterclockwise directions.
-</details>
diff --git a/problems/distant-barcodes/README.md b/problems/distant-barcodes/README.md
deleted file mode 100644
index dc8ebc8b1..000000000
--- a/problems/distant-barcodes/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../previous-permutation-with-one-swap "Previous Permutation With One Swap")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-way-to-form-string "Shortest Way to Form String")
-
-## [1054. Distant Barcodes (Medium)](https://leetcode.com/problems/distant-barcodes "距离相等的条形码")
-
-<p>In a warehouse, there is a row of barcodes, where the <code>i<sup>th</sup></code> barcode is <code>barcodes[i]</code>.</p>
-
-<p>Rearrange the barcodes so that no two adjacent barcodes are equal. You may return any answer, and it is guaranteed an answer exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> barcodes = [1,1,1,2,2,2]
-<strong>Output:</strong> [2,1,2,1,2,1]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> barcodes = [1,1,1,1,2,2,3,3]
-<strong>Output:</strong> [1,3,1,3,1,2,1,2]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= barcodes.length &lt;= 10000</code></li>
-	<li><code>1 &lt;= barcodes[i] &lt;= 10000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We want to always choose the most common or second most common element to write next.  What data structure allows us to query this effectively?
-</details>
diff --git a/problems/distant-barcodes/distant_barcodes.go b/problems/distant-barcodes/distant_barcodes.go
deleted file mode 100644
index d976f23f7..000000000
--- a/problems/distant-barcodes/distant_barcodes.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem1054
-
-import "sort"
-
-func rearrangeBarcodes(A []int) []int {
-	n := len(A)
-
-	count := [10001]int{}
-	for _, a := range A {
-		count[a]++
-	}
-
-	sort.Slice(A, func(i int, j int) bool {
-		if count[A[i]] == count[A[j]] {
-			return A[i] < A[j]
-		}
-		return count[A[i]] > count[A[j]]
-	})
-
-	res := make([]int, n)
-	i := 0
-	for _, a := range A {
-		res[i] = a
-		i += 2
-		if i >= n {
-			i = 1
-		}
-	}
-
-	return res
-}
diff --git a/problems/distinct-echo-substrings/README.md b/problems/distinct-echo-substrings/README.md
deleted file mode 100644
index e27254199..000000000
--- a/problems/distinct-echo-substrings/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-nodes-with-even-valued-grandparent "Sum of Nodes with Even-Valued Grandparent")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-integer-to-the-sum-of-two-no-zero-integers "Convert Integer to the Sum of Two No-Zero Integers")
-
-## [1316. Distinct Echo Substrings (Hard)](https://leetcode.com/problems/distinct-echo-substrings "不同的循环子字符串")
-
-<p>Return the number of <strong>distinct</strong> non-empty substrings of <code>text</code>&nbsp;that can be written as the concatenation of some string with itself (i.e. it can be written as <code>a + a</code>&nbsp;where <code>a</code> is some string).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;abcabcabc&quot;
-<strong>Output:</strong> 3
-<b>Explanation: </b>The 3 substrings are &quot;abcabc&quot;, &quot;bcabca&quot; and &quot;cabcab&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;leetcodeleetcode&quot;
-<strong>Output:</strong> 2
-<b>Explanation: </b>The 2 substrings are &quot;ee&quot; and &quot;leetcodeleetcode&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= text.length &lt;= 2000</code></li>
-	<li><code>text</code>&nbsp;has only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given a substring of the text, how to check if it can be written as the concatenation of a string with itself ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can do that in linear time, a faster way is to use hashing.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Try all substrings and use hashing to check them.
-</details>
diff --git a/problems/distinct-numbers-in-each-subarray/README.md b/problems/distinct-numbers-in-each-subarray/README.md
deleted file mode 100644
index 7f5aeec91..000000000
--- a/problems/distinct-numbers-in-each-subarray/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-interval-to-include-each-query "Minimum Interval to Include Each Query")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-date-format "Convert Date Format")
-
-## [1852. Distinct Numbers in Each Subarray (Medium)](https://leetcode.com/problems/distinct-numbers-in-each-subarray "每个子数组的数字种类数")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep a frequency map of the elements in each window.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When the frequency of the element is 0, remove it from the map.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The answer to each window is the size of the map.
-</details>
diff --git a/problems/distinct-subsequences-ii/README.md b/problems/distinct-subsequences-ii/README.md
deleted file mode 100644
index f9799dc58..000000000
--- a/problems/distinct-subsequences-ii/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-area-rectangle "Minimum Area Rectangle")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-mountain-array "Valid Mountain Array")
-
-## [940. Distinct Subsequences II (Hard)](https://leetcode.com/problems/distinct-subsequences-ii "不同的子序列 II")
-
-<p>Given a string s, return <em>the number of <strong>distinct non-empty subsequences</strong> of</em> <code>s</code>. Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-A <strong>subsequence</strong> of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e., <code>&quot;ace&quot;</code> is a subsequence of <code>&quot;<u>a</u>b<u>c</u>d<u>e</u>&quot;</code> while <code>&quot;aec&quot;</code> is not.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The 7 distinct subsequences are &quot;a&quot;, &quot;b&quot;, &quot;c&quot;, &quot;ab&quot;, &quot;ac&quot;, &quot;bc&quot;, and &quot;abc&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aba&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The 6 distinct subsequences are &quot;a&quot;, &quot;b&quot;, &quot;ab&quot;, &quot;aa&quot;, &quot;ba&quot;, and &quot;aba&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaa&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The 3 distinct subsequences are &quot;a&quot;, &quot;aa&quot; and &quot;aaa&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 2000</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/distinct-subsequences-ii/distinct_subsequences_ii.go b/problems/distinct-subsequences-ii/distinct_subsequences_ii.go
deleted file mode 100644
index 9ec39aee0..000000000
--- a/problems/distinct-subsequences-ii/distinct_subsequences_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem940
diff --git a/problems/distinct-subsequences-ii/distinct_subsequences_ii_test.go b/problems/distinct-subsequences-ii/distinct_subsequences_ii_test.go
deleted file mode 100644
index 9ec39aee0..000000000
--- a/problems/distinct-subsequences-ii/distinct_subsequences_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem940
diff --git a/problems/distinct-subsequences/README.md b/problems/distinct-subsequences/README.md
deleted file mode 100644
index 56f06d216..000000000
--- a/problems/distinct-subsequences/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flatten-binary-tree-to-linked-list "Flatten Binary Tree to Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../populating-next-right-pointers-in-each-node "Populating Next Right Pointers in Each Node")
-
-## [115. Distinct Subsequences (Hard)](https://leetcode.com/problems/distinct-subsequences "不同的子序列")
-
-<p>Given two strings <code>s</code> and <code>t</code>, return <em>the number of distinct subsequences of <code>s</code> which equals <code>t</code></em>.</p>
-
-<p>A string&#39;s <strong>subsequence</strong> is a new string formed from the original string by deleting some (can be none) of the characters without disturbing the remaining characters&#39; relative positions. (i.e., <code>&quot;ACE&quot;</code> is a subsequence of <code>&quot;ABCDE&quot;</code> while <code>&quot;AEC&quot;</code> is not).</p>
-
-<p>The test cases are generated so that the answer fits on a 32-bit signed integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;rabbbit&quot;, t = &quot;rabbit&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-As shown below, there are 3 ways you can generate &quot;rabbit&quot; from S.
-<code><strong><u>rabb</u></strong>b<strong><u>it</u></strong></code>
-<code><strong><u>ra</u></strong>b<strong><u>bbit</u></strong></code>
-<code><strong><u>rab</u></strong>b<strong><u>bit</u></strong></code>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;babgbag&quot;, t = &quot;bag&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong>
-As shown below, there are 5 ways you can generate &quot;bag&quot; from S.
-<code><strong><u>ba</u></strong>b<u><strong>g</strong></u>bag</code>
-<code><strong><u>ba</u></strong>bgba<strong><u>g</u></strong></code>
-<code><u><strong>b</strong></u>abgb<strong><u>ag</u></strong></code>
-<code>ba<u><strong>b</strong></u>gb<u><strong>ag</strong></u></code>
-<code>babg<strong><u>bag</u></strong></code></pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, t.length &lt;= 1000</code></li>
-	<li><code>s</code> and <code>t</code> consist of English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Number of Unique Good Subsequences](../number-of-unique-good-subsequences) (Hard)
diff --git a/problems/distinct-subsequences/distinct_subsequences.go b/problems/distinct-subsequences/distinct_subsequences.go
deleted file mode 100644
index fdfbbe8cf..000000000
--- a/problems/distinct-subsequences/distinct_subsequences.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem115
diff --git a/problems/distinct-subsequences/distinct_subsequences_test.go b/problems/distinct-subsequences/distinct_subsequences_test.go
deleted file mode 100644
index fdfbbe8cf..000000000
--- a/problems/distinct-subsequences/distinct_subsequences_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem115
diff --git a/problems/distribute-candies-to-people/README.md b/problems/distribute-candies-to-people/README.md
deleted file mode 100644
index e593c51a1..000000000
--- a/problems/distribute-candies-to-people/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-with-maximum-minimum-value "Path With Maximum Minimum Value")
-　　　　　　　　　　　　　　　　
-[Next >](../path-in-zigzag-labelled-binary-tree "Path In Zigzag Labelled Binary Tree")
-
-## [1103. Distribute Candies to People (Easy)](https://leetcode.com/problems/distribute-candies-to-people "分糖果 II")
-
-<p>We distribute some&nbsp;number of <code>candies</code>, to a row of <strong><code>n =&nbsp;num_people</code></strong>&nbsp;people in the following way:</p>
-
-<p>We then give 1 candy to the first person, 2 candies to the second person, and so on until we give <code>n</code>&nbsp;candies to the last person.</p>
-
-<p>Then, we go back to the start of the row, giving <code>n&nbsp;+ 1</code> candies to the first person, <code>n&nbsp;+ 2</code> candies to the second person, and so on until we give <code>2 * n</code>&nbsp;candies to the last person.</p>
-
-<p>This process repeats (with us giving one more candy each time, and moving to the start of the row after we reach the end) until we run out of candies.&nbsp; The last person will receive all of our remaining candies (not necessarily one more than the previous gift).</p>
-
-<p>Return an array (of length <code>num_people</code>&nbsp;and sum <code>candies</code>) that represents the final distribution of candies.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> candies = 7, num_people = 4
-<strong>Output:</strong> [1,2,3,1]
-<strong>Explanation:</strong>
-On the first turn, ans[0] += 1, and the array is [1,0,0,0].
-On the second turn, ans[1] += 2, and the array is [1,2,0,0].
-On the third turn, ans[2] += 3, and the array is [1,2,3,0].
-On the fourth turn, ans[3] += 1 (because there is only one candy left), and the final array is [1,2,3,1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> candies = 10, num_people = 3
-<strong>Output:</strong> [5,2,3]
-<strong>Explanation: </strong>
-On the first turn, ans[0] += 1, and the array is [1,0,0].
-On the second turn, ans[1] += 2, and the array is [1,2,0].
-On the third turn, ans[2] += 3, and the array is [1,2,3].
-On the fourth turn, ans[0] += 4, and the final array is [5,2,3].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>1 &lt;= candies &lt;= 10^9</li>
-	<li>1 &lt;= num_people &lt;= 1000</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Give candy to everyone each "turn" first [until you can't], then give candy to one person per turn.
-</details>
diff --git a/problems/distribute-candies-to-people/distribute_candies_to_people.go b/problems/distribute-candies-to-people/distribute_candies_to_people.go
deleted file mode 100644
index 140c27e2b..000000000
--- a/problems/distribute-candies-to-people/distribute_candies_to_people.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1103
diff --git a/problems/distribute-candies/README.md b/problems/distribute-candies/README.md
deleted file mode 100644
index 597d2572d..000000000
--- a/problems/distribute-candies/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../winning-candidate "Winning Candidate")
-　　　　　　　　　　　　　　　　
-[Next >](../out-of-boundary-paths "Out of Boundary Paths")
-
-## [575. Distribute Candies (Easy)](https://leetcode.com/problems/distribute-candies "分糖果")
-
-<p>Alice has <code>n</code> candies, where the <code>i<sup>th</sup></code> candy is of type <code>candyType[i]</code>. Alice noticed that she started to gain weight, so she visited a doctor.</p>
-
-<p>The doctor advised Alice to only eat <code>n / 2</code> of the candies she has (<code>n</code> is always even). Alice likes her candies very much, and she wants to eat the maximum number of different types of candies while still following the doctor&#39;s advice.</p>
-
-<p>Given the integer array <code>candyType</code> of length <code>n</code>, return <em>the <strong>maximum</strong> number of different types of candies she can eat if she only eats </em><code>n / 2</code><em> of them</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> candyType = [1,1,2,2,3,3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Alice can only eat 6 / 2 = 3 candies. Since there are only 3 types, she can eat one of each type.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> candyType = [1,1,2,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Alice can only eat 4 / 2 = 2 candies. Whether she eats types [1,2], [1,3], or [2,3], she still can only eat 2 different types.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> candyType = [6,6,6,6]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Alice can only eat 4 / 2 = 2 candies. Even though she can eat 2 candies, she only has 1 type.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == candyType.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>n</code>&nbsp;is even.</li>
-	<li><code>-10<sup>5</sup> &lt;= candyType[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-To maximize the number of kinds of candies, we should try to distribute candies such that sister will gain all kinds.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What is the upper limit of the number of kinds of candies sister will gain? Remember candies are to distributed equally.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Which data structure is the most suitable for finding the number of kinds of candies?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Will hashset solves the problem? Inserting all candies kind in the hashset and then checking its size with upper limit.
-</details>
diff --git a/problems/distribute-candies/distribute_candies.go b/problems/distribute-candies/distribute_candies.go
deleted file mode 100644
index c36fd623f..000000000
--- a/problems/distribute-candies/distribute_candies.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem575
diff --git a/problems/distribute-candies/distribute_candies_test.go b/problems/distribute-candies/distribute_candies_test.go
deleted file mode 100644
index c36fd623f..000000000
--- a/problems/distribute-candies/distribute_candies_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem575
diff --git a/problems/distribute-coins-in-binary-tree/README.md b/problems/distribute-coins-in-binary-tree/README.md
deleted file mode 100644
index fe77331b2..000000000
--- a/problems/distribute-coins-in-binary-tree/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-turbulent-subarray "Longest Turbulent Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-paths-iii "Unique Paths III")
-
-## [979. Distribute Coins in Binary Tree (Medium)](https://leetcode.com/problems/distribute-coins-in-binary-tree "在二叉树中分配硬币")
-
-<p>You are given the <code>root</code> of a binary tree with <code>n</code> nodes where each <code>node</code> in the tree has <code>node.val</code> coins. There are <code>n</code> coins in total throughout the whole tree.</p>
-
-<p>In one move, we may choose two adjacent nodes and move one coin from one node to another. A move may be from parent to child, or from child to parent.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of moves required to make every node have <strong>exactly</strong> one coin</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/18/tree1.png" style="width: 250px; height: 236px;" />
-<pre>
-<strong>Input:</strong> root = [3,0,0]
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>From the root of the tree, we move one coin to its left child, and one coin to its right child.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/18/tree2.png" style="width: 250px; height: 236px;" />
-<pre>
-<strong>Input:</strong> root = [0,3,0]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>From the left child of the root, we move two coins to the root [taking two moves]. Then, we move one coin from the root of the tree to the right child.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is <code>n</code>.</li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>0 &lt;= Node.val &lt;= n</code></li>
-	<li>The sum of all <code>Node.val</code> is <code>n</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Sum of Distances in Tree](../sum-of-distances-in-tree) (Hard)
-  1. [Binary Tree Cameras](../binary-tree-cameras) (Hard)
diff --git a/problems/distribute-coins-in-binary-tree/distribute_coins_in_binary_tree.go b/problems/distribute-coins-in-binary-tree/distribute_coins_in_binary_tree.go
deleted file mode 100644
index 5af74715b..000000000
--- a/problems/distribute-coins-in-binary-tree/distribute_coins_in_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem979
diff --git a/problems/distribute-repeating-integers/README.md b/problems/distribute-repeating-integers/README.md
deleted file mode 100644
index c9c238bd3..000000000
--- a/problems/distribute-repeating-integers/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-jumps-to-reach-home "Minimum Jumps to Reach Home")
-　　　　　　　　　　　　　　　　
-[Next >](../design-an-ordered-stream "Design an Ordered Stream")
-
-## [1655. Distribute Repeating Integers (Hard)](https://leetcode.com/problems/distribute-repeating-integers "分配重复整数")
-
-<p>You are given an array of <code>n</code> integers, <code>nums</code>, where there are at most <code>50</code> unique values in the array. You are also given an array of <code>m</code> customer order quantities, <code>quantity</code>, where <code>quantity[i]</code> is the amount of integers the <code>i<sup>th</sup></code> customer ordered. Determine if it is possible to distribute <code>nums</code> such that:</p>
-
-<ul>
-	<li>The <code>i<sup>th</sup></code> customer gets <strong>exactly</strong> <code>quantity[i]</code> integers,</li>
-	<li>The integers the <code>i<sup>th</sup></code> customer gets are <strong>all equal</strong>, and</li>
-	<li>Every customer is satisfied.</li>
-</ul>
-
-<p>Return <code>true</code><em> if it is possible to distribute </em><code>nums</code><em> according to the above conditions</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4], quantity = [2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The 0<sup>th</sup> customer cannot be given two different integers.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,3], quantity = [2]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The 0<sup>th</sup> customer is given [3,3]. The integers [1,2] are not used.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,2,2], quantity = [2,2]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The 0<sup>th</sup> customer is given [1,1], and the 1st customer is given [2,2].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 1000</code></li>
-	<li><code>m == quantity.length</code></li>
-	<li><code>1 &lt;= m &lt;= 10</code></li>
-	<li><code>1 &lt;= quantity[i] &lt;= 10<sup>5</sup></code></li>
-	<li>There are at most <code>50</code> unique values in <code>nums</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the frequencies of each number. For example, if nums = [4,4,5,5,5], frequencies = [2,3].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Each customer wants all of their numbers to be the same. This means that each customer will be assigned to one number.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use dynamic programming. Iterate through the numbers' frequencies, and choose some subset of customers to be assigned to this number.
-</details>
diff --git a/problems/divide-a-string-into-groups-of-size-k/README.md b/problems/divide-a-string-into-groups-of-size-k/README.md
deleted file mode 100644
index f7fc58e35..000000000
--- a/problems/divide-a-string-into-groups-of-size-k/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pour-water-between-buckets-to-make-water-levels-equal "Pour Water Between Buckets to Make Water Levels Equal")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-moves-to-reach-target-score "Minimum Moves to Reach Target Score")
-
-## [2138. Divide a String Into Groups of Size k (Easy)](https://leetcode.com/problems/divide-a-string-into-groups-of-size-k "将字符串拆分为若干长度为 k 的组")
-
-<p>A string <code>s</code> can be partitioned into groups of size <code>k</code> using the following procedure:</p>
-
-<ul>
-	<li>The first group consists of the first <code>k</code> characters of the string, the second group consists of the next <code>k</code> characters of the string, and so on. Each character can be a part of <strong>exactly one</strong> group.</li>
-	<li>For the last group, if the string <strong>does not</strong> have <code>k</code> characters remaining, a character <code>fill</code> is used to complete the group.</li>
-</ul>
-
-<p>Note that the partition is done so that after removing the <code>fill</code> character from the last group (if it exists) and concatenating all the groups in order, the resultant string should be <code>s</code>.</p>
-
-<p>Given the string <code>s</code>, the size of each group <code>k</code> and the character <code>fill</code>, return <em>a string array denoting the <strong>composition of every group</strong> </em><code>s</code><em> has been divided into, using the above procedure</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcdefghi&quot;, k = 3, fill = &quot;x&quot;
-<strong>Output:</strong> [&quot;abc&quot;,&quot;def&quot;,&quot;ghi&quot;]
-<strong>Explanation:</strong>
-The first 3 characters &quot;abc&quot; form the first group.
-The next 3 characters &quot;def&quot; form the second group.
-The last 3 characters &quot;ghi&quot; form the third group.
-Since all groups can be completely filled by characters from the string, we do not need to use fill.
-Thus, the groups formed are &quot;abc&quot;, &quot;def&quot;, and &quot;ghi&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcdefghij&quot;, k = 3, fill = &quot;x&quot;
-<strong>Output:</strong> [&quot;abc&quot;,&quot;def&quot;,&quot;ghi&quot;,&quot;jxx&quot;]
-<strong>Explanation:</strong>
-Similar to the previous example, we are forming the first three groups &quot;abc&quot;, &quot;def&quot;, and &quot;ghi&quot;.
-For the last group, we can only use the character &#39;j&#39; from the string. To complete this group, we add &#39;x&#39; twice.
-Thus, the 4 groups formed are &quot;abc&quot;, &quot;def&quot;, &quot;ghi&quot;, and &quot;jxx&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> consists of lowercase English letters only.</li>
-	<li><code>1 &lt;= k &lt;= 100</code></li>
-	<li><code>fill</code> is a lowercase English letter.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Using the length of the string and k, can you count the number of groups the string can be divided into?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try completing each group using characters from the string. If there aren’t enough characters for the last group, use the fill character to complete the group.
-</details>
diff --git a/problems/divide-array-in-sets-of-k-consecutive-numbers/README.md b/problems/divide-array-in-sets-of-k-consecutive-numbers/README.md
deleted file mode 100644
index 99aa7bbf4..000000000
--- a/problems/divide-array-in-sets-of-k-consecutive-numbers/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-numbers-with-even-number-of-digits "Find Numbers with Even Number of Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-occurrences-of-a-substring "Maximum Number of Occurrences of a Substring")
-
-## [1296. Divide Array in Sets of K Consecutive Numbers (Medium)](https://leetcode.com/problems/divide-array-in-sets-of-k-consecutive-numbers "划分数组为连续数字的集合")
-
-<p>Given an array of integers <code>nums</code> and a positive integer <code>k</code>, find whether it is possible to divide this array into sets of <code>k</code> consecutive numbers.</p>
-
-<p>Return <code>true</code> <em>if it is possible</em>.<strong> </strong>Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,3,4,4,5,6], k = 4
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Array can be divided into [1,2,3,4] and [3,4,5,6].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,1,2,3,4,3,4,5,9,10,11], k = 3
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Array can be divided into [1,2,3] , [2,3,4] , [3,4,5] and [9,10,11].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,3,2,2,1,1], k = 3
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4], k = 3
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Each array should be divided in subarrays of size 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Note:</strong> This question is the same as&nbsp;846:&nbsp;<a href="https://leetcode.com/problems/hand-of-straights/" target="_blank">https://leetcode.com/problems/hand-of-straights/</a>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Split Array into Consecutive Subsequences](../split-array-into-consecutive-subsequences) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the smallest number in the possible-to-split array is V, then numbers V+1, V+2, ... V+k-1 must contain there as well.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can iteratively find k sets and remove them from array until it becomes empty.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Failure to do so would mean that array is unsplittable.
-</details>
diff --git a/problems/divide-array-into-increasing-sequences/README.md b/problems/divide-array-into-increasing-sequences/README.md
deleted file mode 100644
index 6863391eb..000000000
--- a/problems/divide-array-into-increasing-sequences/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-average-subtree "Maximum Average Subtree")
-　　　　　　　　　　　　　　　　
-[Next >](../relative-sort-array "Relative Sort Array")
-
-## [1121. Divide Array Into Increasing Sequences (Hard)](https://leetcode.com/problems/divide-array-into-increasing-sequences "将数组分成几个递增序列")
-
-<p>Given a <strong>non-decreasing</strong> array of positive integers&nbsp;<code>nums</code>&nbsp;and an integer <code>K</code>, find out if this array can be divided into one or more <strong>disjoint increasing subsequences of length at least</strong> <code>K</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>nums = <span id="example-input-1-1">[1,2,2,3,3,4,4]</span>, K = <span id="example-input-1-2">3</span>
-<strong>Output: </strong><span id="example-output-1">true</span>
-<strong>Explanation: </strong>
-The array can be divided into the two subsequences [1,2,3,4] and [2,3,4] with lengths at least 3 each.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>nums = <span id="example-input-2-1">[5,6,6,7,8]</span>, K = <span id="example-input-2-2">3</span>
-<strong>Output: </strong><span id="example-output-2">false</span>
-<strong>Explanation: </strong>
-There is no way to divide the array using the conditions required.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= nums.length&nbsp;&lt;= 10^5</code></li>
-	<li><code>1 &lt;= K &lt;= nums.length</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10^5</code></li>
-</ol>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think in the frequency of the numbers and how this affects the number of sequences needed.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What is the minimum number of sequences we need to form? Considering frequency of the numbers.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Think about the least number of sequences to maximize the lengths.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The number of sequences needed is equal to the maximum frequency of an element.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-How to put the other elements into sequences ? Think in a greedy approach.
-</details>
diff --git a/problems/divide-chocolate/README.md b/problems/divide-chocolate/README.md
deleted file mode 100644
index 4d9a7d8cf..000000000
--- a/problems/divide-chocolate/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../toss-strange-coins "Toss Strange Coins")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-it-is-a-straight-line "Check If It Is a Straight Line")
-
-## [1231. Divide Chocolate (Hard)](https://leetcode.com/problems/divide-chocolate "分享巧克力")
-
-<p>You have one chocolate bar that consists of some chunks. Each chunk has its own sweetness given by the array&nbsp;<code>sweetness</code>.</p>
-
-<p>You want to share the chocolate with your <code>K</code>&nbsp;friends so you start cutting the chocolate bar into <code>K+1</code>&nbsp;pieces using&nbsp;<code>K</code>&nbsp;cuts, each piece consists of some <strong>consecutive</strong> chunks.</p>
-
-<p>Being generous, you will eat the piece with the <strong>minimum total sweetness</strong> and give the other pieces to your friends.</p>
-
-<p>Find the <strong>maximum total sweetness</strong> of the&nbsp;piece you can get by cutting the chocolate bar optimally.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> sweetness = [1,2,3,4,5,6,7,8,9], K = 5
-<strong>Output:</strong> 6
-<b>Explanation: </b>You can divide the chocolate to [1,2,3], [4,5], [6], [7], [8], [9]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> sweetness = [5,6,7,8,9,1,2,3,4], K = 8
-<strong>Output:</strong> 1
-<b>Explanation: </b>There is only one way to cut the bar into 9 pieces.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> sweetness = [1,2,2,1,2,2,1,2,2], K = 2
-<strong>Output:</strong> 5
-<b>Explanation: </b>You can divide the chocolate to [1,2,2], [1,2,2], [1,2,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= K &lt;&nbsp;sweetness.length &lt;= 10^4</code></li>
-	<li><code>1 &lt;= sweetness[i] &lt;= 10^5</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-After dividing the array into K+1 sub-arrays, you will pick the sub-array with the minimum sum.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Divide the sub-array into K+1 sub-arrays such that the minimum sub-array sum is as maximum as possible.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use binary search with greedy check.
-</details>
diff --git a/problems/divide-two-integers/README.md b/problems/divide-two-integers/README.md
deleted file mode 100644
index 54a10c62f..000000000
--- a/problems/divide-two-integers/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../implement-strstr "Implement strStr()")
-　　　　　　　　　　　　　　　　
-[Next >](../substring-with-concatenation-of-all-words "Substring with Concatenation of All Words")
-
-## [29. Divide Two Integers (Medium)](https://leetcode.com/problems/divide-two-integers "两数相除")
-
-<p>Given two integers <code>dividend</code> and <code>divisor</code>, divide two integers without using multiplication, division, and mod operator.</p>
-
-<p>Return the quotient after dividing <code>dividend</code> by <code>divisor</code>.</p>
-
-<p>The integer division should truncate toward zero, which means losing its fractional part. For example, <code>truncate(8.345) = 8</code> and <code>truncate(-2.7335) = -2</code>.</p>
-
-<p><strong>Note: </strong>Assume we are dealing with an environment that could only store integers within the <strong>32-bit</strong> signed integer range: <code>[&minus;2<sup>31</sup>, 2<sup>31</sup> &minus; 1]</code>. For this problem, assume that your function <strong>returns </strong><code>2<sup>31</sup> &minus; 1</code><strong> when the division result overflows</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> dividend = 10, divisor = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 10/3 = truncate(3.33333..) = 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> dividend = 7, divisor = -3
-<strong>Output:</strong> -2
-<strong>Explanation:</strong> 7/-3 = truncate(-2.33333..) = -2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> dividend = 0, divisor = 1
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> dividend = 1, divisor = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= dividend, divisor &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>divisor != 0</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/divide-two-integers/divide_two_integers.go b/problems/divide-two-integers/divide_two_integers.go
deleted file mode 100644
index ad9d300a2..000000000
--- a/problems/divide-two-integers/divide_two_integers.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem29
diff --git a/problems/divide-two-integers/divide_two_integers_test.go b/problems/divide-two-integers/divide_two_integers_test.go
deleted file mode 100644
index ad9d300a2..000000000
--- a/problems/divide-two-integers/divide_two_integers_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem29
diff --git a/problems/divisor-game/README.md b/problems/divisor-game/README.md
deleted file mode 100644
index c6f148423..000000000
--- a/problems/divisor-game/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../video-stitching "Video Stitching")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-difference-between-node-and-ancestor "Maximum Difference Between Node and Ancestor")
-
-## [1025. Divisor Game (Easy)](https://leetcode.com/problems/divisor-game "除数博弈")
-
-<p>Alice and Bob take turns playing a game, with Alice starting first.</p>
-
-<p>Initially, there is a number <code>n</code> on the chalkboard. On each player&#39;s turn, that player makes a move consisting of:</p>
-
-<ul>
-	<li>Choosing any <code>x</code> with <code>0 &lt; x &lt; n</code> and <code>n % x == 0</code>.</li>
-	<li>Replacing the number <code>n</code> on the chalkboard with <code>n - x</code>.</li>
-</ul>
-
-<p>Also, if a player cannot make a move, they lose the game.</p>
-
-<p>Return <code>true</code> <em>if and only if Alice wins the game, assuming both players play optimally</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Alice chooses 1, and Bob has no more moves.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Alice chooses 1, Bob chooses 1, and Alice has no more moves.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Brainteaser](../../tag/brainteaser/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the current number is even, we can always subtract a 1 to make it odd.  If the current number is odd, we must subtract an odd number to make it even.
-</details>
diff --git a/problems/divisor-game/divisor_game.go b/problems/divisor-game/divisor_game.go
deleted file mode 100644
index 1734be824..000000000
--- a/problems/divisor-game/divisor_game.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem1025
-
-func divisorGame(N int) bool {
-	return N&1 == 0
-}
diff --git a/problems/divisor-game/divisor_game_test.go b/problems/divisor-game/divisor_game_test.go
deleted file mode 100644
index af1ba4b2d..000000000
--- a/problems/divisor-game/divisor_game_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem1025
-
-import "testing"
-
-type testType struct {
-	in   int
-	want bool
-}
-
-func TestDivisorGame(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   2,
-			want: true,
-		},
-		{
-			in:   3,
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := divisorGame(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/domino-and-tromino-tiling/README.md b/problems/domino-and-tromino-tiling/README.md
deleted file mode 100644
index 0aab6467f..000000000
--- a/problems/domino-and-tromino-tiling/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../escape-the-ghosts "Escape The Ghosts")
-　　　　　　　　　　　　　　　　
-[Next >](../custom-sort-string "Custom Sort String")
-
-## [790. Domino and Tromino Tiling (Medium)](https://leetcode.com/problems/domino-and-tromino-tiling "多米诺和托米诺平铺")
-
-<p>You have two types of tiles: a <code>2 x 1</code> domino shape and a tromino shape. You may rotate these shapes.</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/15/lc-domino.jpg" style="width: 362px; height: 195px;" />
-<p>Given an integer n, return <em>the number of ways to tile an</em> <code>2 x n</code> <em>board</em>. Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>In a tiling, every square must be covered by a tile. Two tilings are different if and only if there are two 4-directionally adjacent cells on the board such that exactly one of the tilings has both squares occupied by a tile.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/15/lc-domino1.jpg" style="width: 500px; height: 226px;" />
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The five different ways are show above.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/domino-and-tromino-tiling/domino_and_tromino_tiling.go b/problems/domino-and-tromino-tiling/domino_and_tromino_tiling.go
deleted file mode 100644
index e70dfcb9c..000000000
--- a/problems/domino-and-tromino-tiling/domino_and_tromino_tiling.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem790
diff --git a/problems/domino-and-tromino-tiling/domino_and_tromino_tiling_test.go b/problems/domino-and-tromino-tiling/domino_and_tromino_tiling_test.go
deleted file mode 100644
index e70dfcb9c..000000000
--- a/problems/domino-and-tromino-tiling/domino_and_tromino_tiling_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem790
diff --git a/problems/dot-product-of-two-sparse-vectors/README.md b/problems/dot-product-of-two-sparse-vectors/README.md
deleted file mode 100644
index 4dd93440a..000000000
--- a/problems/dot-product-of-two-sparse-vectors/README.md
+++ /dev/null
@@ -1,26 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-reorder-array-to-get-same-bst "Number of Ways to Reorder Array to Get Same BST")
-　　　　　　　　　　　　　　　　
-[Next >](../warehouse-manager "Warehouse Manager")
-
-## [1570. Dot Product of Two Sparse Vectors (Medium)](https://leetcode.com/problems/dot-product-of-two-sparse-vectors "两个稀疏向量的点积")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Because the vector is sparse, use a data structure that stores the index and value where the element is nonzero.
-</details>
diff --git a/problems/dota2-senate/README.md b/problems/dota2-senate/README.md
deleted file mode 100644
index 9d40d16ad..000000000
--- a/problems/dota2-senate/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../replace-words "Replace Words")
-　　　　　　　　　　　　　　　　
-[Next >](../2-keys-keyboard "2 Keys Keyboard")
-
-## [649. Dota2 Senate (Medium)](https://leetcode.com/problems/dota2-senate "Dota2 参议院")
-
-<p>In the world of Dota2, there are two parties: the Radiant and the Dire.</p>
-
-<p>The Dota2 senate consists of senators coming from two parties. Now the Senate wants to decide on a change in the Dota2 game. The voting for this change is a round-based procedure. In each round, each senator can exercise <strong>one</strong> of the two rights:</p>
-
-<ul>
-	<li><strong>Ban one senator&#39;s right:</strong> A senator can make another senator lose all his rights in this and all the following rounds.</li>
-	<li><strong>Announce the victory:</strong> If this senator found the senators who still have rights to vote are all from the same party, he can announce the victory and decide on the change in the game.</li>
-</ul>
-
-<p>Given a string <code>senate</code> representing each senator&#39;s party belonging. The character <code>&#39;R&#39;</code> and <code>&#39;D&#39;</code> represent the Radiant party and the Dire party. Then if there are <code>n</code> senators, the size of the given string will be <code>n</code>.</p>
-
-<p>The round-based procedure starts from the first senator to the last senator in the given order. This procedure will last until the end of voting. All the senators who have lost their rights will be skipped during the procedure.</p>
-
-<p>Suppose every senator is smart enough and will play the best strategy for his own party. Predict which party will finally announce the victory and change the Dota2 game. The output should be <code>&quot;Radiant&quot;</code> or <code>&quot;Dire&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> senate = &quot;RD&quot;
-<strong>Output:</strong> &quot;Radiant&quot;
-<strong>Explanation:</strong> 
-The first senator comes from Radiant and he can just ban the next senator&#39;s right in round 1. 
-And the second senator can&#39;t exercise any rights anymore since his right has been banned. 
-And in round 2, the first senator can just announce the victory since he is the only guy in the senate who can vote.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> senate = &quot;RDD&quot;
-<strong>Output:</strong> &quot;Dire&quot;
-<strong>Explanation:</strong> 
-The first senator comes from Radiant and he can just ban the next senator&#39;s right in round 1. 
-And the second senator can&#39;t exercise any rights anymore since his right has been banned. 
-And the third senator comes from Dire and he can ban the first senator&#39;s right in round 1. 
-And in round 2, the third senator can just announce the victory since he is the only guy in the senate who can vote.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == senate.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>senate[i]</code> is either <code>&#39;R&#39;</code> or <code>&#39;D&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-
-### Similar Questions
-  1. [Teemo Attacking](../teemo-attacking) (Easy)
diff --git a/problems/dota2-senate/dota2_senate.go b/problems/dota2-senate/dota2_senate.go
deleted file mode 100644
index 8a89517e7..000000000
--- a/problems/dota2-senate/dota2_senate.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem649
diff --git a/problems/dota2-senate/dota2_senate_test.go b/problems/dota2-senate/dota2_senate_test.go
deleted file mode 100644
index 8a89517e7..000000000
--- a/problems/dota2-senate/dota2_senate_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem649
diff --git a/problems/drop-type-1-orders-for-customers-with-type-0-orders/README.md b/problems/drop-type-1-orders-for-customers-with-type-0-orders/README.md
deleted file mode 100644
index 015d77373..000000000
--- a/problems/drop-type-1-orders-for-customers-with-type-0-orders/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../substrings-that-begin-and-end-with-the-same-letter "Substrings That Begin and End With the Same Letter")
-　　　　　　　　　　　　　　　　
-[Next >](../count-common-words-with-one-occurrence "Count Common Words With One Occurrence")
-
-## [2084. Drop Type 1 Orders for Customers With Type 0 Orders (Medium)](https://leetcode.com/problems/drop-type-1-orders-for-customers-with-type-0-orders "为订单类型为 0 的客户删除类型为 1 的订单")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/drop-type-1-orders-for-customers-with-type-0-orders/mysql_schemas.sql b/problems/drop-type-1-orders-for-customers-with-type-0-orders/mysql_schemas.sql
deleted file mode 100644
index 22a499aa9..000000000
--- a/problems/drop-type-1-orders-for-customers-with-type-0-orders/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Orders (order_id int, customer_id int, order_type int);
-Truncate table Orders;
-insert into Orders (order_id, customer_id, order_type) values ('1', '1', '0');
-insert into Orders (order_id, customer_id, order_type) values ('2', '1', '0');
-insert into Orders (order_id, customer_id, order_type) values ('11', '2', '0');
-insert into Orders (order_id, customer_id, order_type) values ('12', '2', '1');
-insert into Orders (order_id, customer_id, order_type) values ('21', '3', '1');
-insert into Orders (order_id, customer_id, order_type) values ('22', '3', '0');
-insert into Orders (order_id, customer_id, order_type) values ('31', '4', '1');
-insert into Orders (order_id, customer_id, order_type) values ('32', '4', '1');
diff --git a/problems/dungeon-game/README.md b/problems/dungeon-game/README.md
deleted file mode 100644
index 481597181..000000000
--- a/problems/dungeon-game/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-search-tree-iterator "Binary Search Tree Iterator")
-　　　　　　　　　　　　　　　　
-[Next >](../combine-two-tables "Combine Two Tables")
-
-## [174. Dungeon Game (Hard)](https://leetcode.com/problems/dungeon-game "地下城游戏")
-
-<p>The demons had captured the princess and imprisoned her in <strong>the bottom-right corner</strong> of a <code>dungeon</code>. The <code>dungeon</code> consists of <code>m x n</code> rooms laid out in a 2D grid. Our valiant knight was initially positioned in <strong>the top-left room</strong> and must fight his way through <code>dungeon</code> to rescue the princess.</p>
-
-<p>The knight has an initial health point represented by a positive integer. If at any point his health point drops to <code>0</code> or below, he dies immediately.</p>
-
-<p>Some of the rooms are guarded by demons (represented by negative integers), so the knight loses health upon entering these rooms; other rooms are either empty (represented as 0) or contain magic orbs that increase the knight&#39;s health (represented by positive integers).</p>
-
-<p>To reach the princess as quickly as possible, the knight decides to move only <strong>rightward</strong> or <strong>downward</strong> in each step.</p>
-
-<p>Return <em>the knight&#39;s minimum initial health so that he can rescue the princess</em>.</p>
-
-<p><strong>Note</strong> that any room can contain threats or power-ups, even the first room the knight enters and the bottom-right room where the princess is imprisoned.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/13/dungeon-grid-1.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> dungeon = [[-2,-3,3],[-5,-10,1],[10,30,-5]]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The initial health of the knight must be at least 7 if he follows the optimal path: RIGHT-&gt; RIGHT -&gt; DOWN -&gt; DOWN.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> dungeon = [[0]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == dungeon.length</code></li>
-	<li><code>n == dungeon[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>-1000 &lt;= dungeon[i][j] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Unique Paths](../unique-paths) (Medium)
-  1. [Minimum Path Sum](../minimum-path-sum) (Medium)
-  1. [Cherry Pickup](../cherry-pickup) (Hard)
diff --git a/problems/dungeon-game/dungeon_game.go b/problems/dungeon-game/dungeon_game.go
deleted file mode 100644
index 5376012c4..000000000
--- a/problems/dungeon-game/dungeon_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem174
diff --git a/problems/dungeon-game/dungeon_game_test.go b/problems/dungeon-game/dungeon_game_test.go
deleted file mode 100644
index 5376012c4..000000000
--- a/problems/dungeon-game/dungeon_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem174
diff --git a/problems/duplicate-emails/README.md b/problems/duplicate-emails/README.md
deleted file mode 100644
index d03810ad8..000000000
--- a/problems/duplicate-emails/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../employees-earning-more-than-their-managers "Employees Earning More Than Their Managers")
-　　　　　　　　　　　　　　　　
-[Next >](../customers-who-never-order "Customers Who Never Order")
-
-## [182. Duplicate Emails (Easy)](https://leetcode.com/problems/duplicate-emails "查找重复的电子邮箱")
-
-<p>Table: <code>Person</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| id          | int     |
-| email       | varchar |
-+-------------+---------+
-id is the primary key column for this table.
-Each row of this table contains an email. The emails will not contain uppercase letters.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to report all the duplicate emails.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Person table:
-+----+---------+
-| id | email   |
-+----+---------+
-| 1  | a@b.com |
-| 2  | c@d.com |
-| 3  | a@b.com |
-+----+---------+
-<strong>Output:</strong> 
-+---------+
-| Email   |
-+---------+
-| a@b.com |
-+---------+
-<strong>Explanation:</strong> a@b.com is repeated two times.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/duplicate-emails/duplicate_emails.sql b/problems/duplicate-emails/duplicate_emails.sql
deleted file mode 100644
index c6d93cf24..000000000
--- a/problems/duplicate-emails/duplicate_emails.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT
-  Email
-FROM
-  Person
-GROUP BY
-  Email
-HAVING
-  count(1) > 1;
diff --git a/problems/duplicate-emails/mysql_schemas.sql b/problems/duplicate-emails/mysql_schemas.sql
deleted file mode 100644
index 5e65f14b1..000000000
--- a/problems/duplicate-emails/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create table If Not Exists Person (id int, email varchar(255));
-Truncate table Person;
-insert into Person (id, email) values ('1', 'a@b.com');
-insert into Person (id, email) values ('2', 'c@d.com');
-insert into Person (id, email) values ('3', 'a@b.com');
diff --git a/problems/duplicate-zeros/README.md b/problems/duplicate-zeros/README.md
deleted file mode 100644
index c933127d7..000000000
--- a/problems/duplicate-zeros/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../confusing-number-ii "Confusing Number II")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-values-from-labels "Largest Values From Labels")
-
-## [1089. Duplicate Zeros (Easy)](https://leetcode.com/problems/duplicate-zeros "复写零")
-
-<p>Given a fixed-length integer array <code>arr</code>, duplicate each occurrence of zero, shifting the remaining elements to the right.</p>
-
-<p><strong>Note</strong> that elements beyond the length of the original array are not written. Do the above modifications to the input array in place and do not return anything.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,0,2,3,0,4,5,0]
-<strong>Output:</strong> [1,0,0,2,3,0,0,4]
-<strong>Explanation:</strong> After calling your function, the input array is modified to: [1,0,0,2,3,0,0,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3]
-<strong>Output:</strong> [1,2,3]
-<strong>Explanation:</strong> After calling your function, the input array is modified to: [1,2,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-This is a great introductory problem for understanding and working with the concept of in-place operations. The problem statement clearly states that we are to modify the array in-place. That does not mean we cannot use another array. We just don't have to return anything.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-A better way to solve this would be without using additional space. The only reason the problem statement allows you to make modifications in place is that it hints at avoiding any additional memory.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The main problem with not using additional memory is that we might override elements due to the zero duplication requirement of the problem statement. How do we get around that?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-If we had enough space available, we would be able to accommodate all the elements properly. The new length would be the original length of the array plus the number of zeros. Can we use this information somehow to solve the problem?
-</details>
diff --git a/problems/duplicate-zeros/duplicate_zeros.go b/problems/duplicate-zeros/duplicate_zeros.go
deleted file mode 100644
index b3d5b51f3..000000000
--- a/problems/duplicate-zeros/duplicate_zeros.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem1089
-
-func duplicateZeros(A []int) {
-	n := len(A)
-	//
-	count := 0
-	for i := 0; i < n; i++ {
-		if A[i] == 0 {
-			count++
-		}
-	}
-	// copy A[i] to A[j]
-	copy := func(i, j int) {
-		if j < n {
-			A[j] = A[i]
-		}
-	}
-	//
-	i, j := n-1, n+count-1
-	for i < j {
-		copy(i, j)
-		if A[i] == 0 {
-			j--
-			copy(i, j)
-		}
-		i--
-		j--
-	}
-}
diff --git a/problems/earliest-possible-day-of-full-bloom/README.md b/problems/earliest-possible-day-of-full-bloom/README.md
deleted file mode 100644
index ac699a6ed..000000000
--- a/problems/earliest-possible-day-of-full-bloom/README.md
+++ /dev/null
@@ -1,95 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-words-obtained-after-adding-a-letter "Count Words Obtained After Adding a Letter")
-　　　　　　　　　　　　　　　　
-[Next >](../pour-water-between-buckets-to-make-water-levels-equal "Pour Water Between Buckets to Make Water Levels Equal")
-
-## [2136. Earliest Possible Day of Full Bloom (Hard)](https://leetcode.com/problems/earliest-possible-day-of-full-bloom "全部开花的最早一天")
-
-<p>You have <code>n</code> flower seeds. Every seed must be planted first before it can begin to grow, then bloom. Planting a seed takes time and so does the growth of a seed. You are given two <strong>0-indexed</strong> integer arrays <code>plantTime</code> and <code>growTime</code>, of length <code>n</code> each:</p>
-
-<ul>
-	<li><code>plantTime[i]</code> is the number of <strong>full days</strong> it takes you to <strong>plant</strong> the <code>i<sup>th</sup></code> seed. Every day, you can work on planting exactly one seed. You <strong>do not</strong> have to work on planting the same seed on consecutive days, but the planting of a seed is not complete <strong>until</strong> you have worked <code>plantTime[i]</code> days on planting it in total.</li>
-	<li><code>growTime[i]</code> is the number of <strong>full days</strong> it takes the <code>i<sup>th</sup></code> seed to grow after being completely planted. <strong>After</strong> the last day of its growth, the flower <strong>blooms</strong> and stays bloomed forever.</li>
-</ul>
-
-<p>From the beginning of day <code>0</code>, you can plant the seeds in <strong>any</strong> order.</p>
-
-<p>Return <em>the <strong>earliest</strong> possible day where <strong>all</strong> seeds are blooming</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/21/1.png" style="width: 453px; height: 149px;" />
-<pre>
-<strong>Input:</strong> plantTime = [1,4,3], growTime = [2,3,1]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> The grayed out pots represent planting days, colored pots represent growing days, and the flower represents the day it blooms.
-One optimal way is:
-On day 0, plant the 0<sup>th</sup> seed. The seed grows for 2 full days and blooms on day 3.
-On days 1, 2, 3, and 4, plant the 1<sup>st</sup> seed. The seed grows for 3 full days and blooms on day 8.
-On days 5, 6, and 7, plant the 2<sup>nd</sup> seed. The seed grows for 1 full day and blooms on day 9.
-Thus, on day 9, all the seeds are blooming.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/21/2.png" style="width: 454px; height: 184px;" />
-<pre>
-<strong>Input:</strong> plantTime = [1,2,3,2], growTime = [2,1,2,1]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> The grayed out pots represent planting days, colored pots represent growing days, and the flower represents the day it blooms.
-One optimal way is:
-On day 1, plant the 0<sup>th</sup> seed. The seed grows for 2 full days and blooms on day 4.
-On days 0 and 3, plant the 1<sup>st</sup> seed. The seed grows for 1 full day and blooms on day 5.
-On days 2, 4, and 5, plant the 2<sup>nd</sup> seed. The seed grows for 2 full days and blooms on day 8.
-On days 6 and 7, plant the 3<sup>rd</sup> seed. The seed grows for 1 full day and blooms on day 9.
-Thus, on day 9, all the seeds are blooming.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> plantTime = [1], growTime = [1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> On day 0, plant the 0<sup>th</sup> seed. The seed grows for 1 full day and blooms on day 2.
-Thus, on day 2, all the seeds are blooming.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == plantTime.length == growTime.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= plantTime[i], growTime[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-List the planting like the diagram above shows, where a row represents the timeline of a seed. A row i is above another row j if the last day planting seed i is ahead of the last day for seed j. Does it have any advantage to spend some days to plant seed j before completely planting seed i?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-No. It does not help seed j but could potentially delay the completion of seed i, resulting in a worse final answer. Remaining focused is a part of the optimal solution.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Sort the seeds by their growTime in descending order. Can you prove why this strategy is the other part of the optimal solution? Note the bloom time of a seed is the sum of plantTime of all seeds preceding this seed plus the growTime of this seed.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-There is no way to improve this strategy. The seed to bloom last dominates the final answer. Exchanging the planting of this seed with another seed with either a larger or smaller growTime will result in a potentially worse answer.
-</details>
diff --git a/problems/edit-distance/README.md b/problems/edit-distance/README.md
deleted file mode 100644
index 36f4811eb..000000000
--- a/problems/edit-distance/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../simplify-path "Simplify Path")
-　　　　　　　　　　　　　　　　
-[Next >](../set-matrix-zeroes "Set Matrix Zeroes")
-
-## [72. Edit Distance (Hard)](https://leetcode.com/problems/edit-distance "编辑距离")
-
-<p>Given two strings <code>word1</code> and <code>word2</code>, return <em>the minimum number of operations required to convert <code>word1</code> to <code>word2</code></em>.</p>
-
-<p>You have the following three operations permitted on a word:</p>
-
-<ul>
-	<li>Insert a character</li>
-	<li>Delete a character</li>
-	<li>Replace a character</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;horse&quot;, word2 = &quot;ros&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-horse -&gt; rorse (replace &#39;h&#39; with &#39;r&#39;)
-rorse -&gt; rose (remove &#39;r&#39;)
-rose -&gt; ros (remove &#39;e&#39;)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;intention&quot;, word2 = &quot;execution&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> 
-intention -&gt; inention (remove &#39;t&#39;)
-inention -&gt; enention (replace &#39;i&#39; with &#39;e&#39;)
-enention -&gt; exention (replace &#39;n&#39; with &#39;x&#39;)
-exention -&gt; exection (replace &#39;n&#39; with &#39;c&#39;)
-exection -&gt; execution (insert &#39;u&#39;)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= word1.length, word2.length &lt;= 500</code></li>
-	<li><code>word1</code> and <code>word2</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [One Edit Distance](../one-edit-distance) (Medium)
-  1. [Delete Operation for Two Strings](../delete-operation-for-two-strings) (Medium)
-  1. [Minimum ASCII Delete Sum for Two Strings](../minimum-ascii-delete-sum-for-two-strings) (Medium)
-  1. [Uncrossed Lines](../uncrossed-lines) (Medium)
diff --git a/problems/edit-distance/edit_distance.go b/problems/edit-distance/edit_distance.go
deleted file mode 100644
index 1dda62473..000000000
--- a/problems/edit-distance/edit_distance.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem72
diff --git a/problems/edit-distance/edit_distance_test.go b/problems/edit-distance/edit_distance_test.go
deleted file mode 100644
index 1dda62473..000000000
--- a/problems/edit-distance/edit_distance_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem72
diff --git a/problems/egg-drop-with-2-eggs-and-n-floors/README.md b/problems/egg-drop-with-2-eggs-and-n-floors/README.md
deleted file mode 100644
index fb4e7cc26..000000000
--- a/problems/egg-drop-with-2-eggs-and-n-floors/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-skips-to-arrive-at-meeting-on-time "Minimum Skips to Arrive at Meeting On Time")
-　　　　　　　　　　　　　　　　
-[Next >](../count-pairs-in-two-arrays "Count Pairs in Two Arrays")
-
-## [1884. Egg Drop With 2 Eggs and N Floors (Medium)](https://leetcode.com/problems/egg-drop-with-2-eggs-and-n-floors "鸡蛋掉落-两枚鸡蛋")
-
-<p>You are given <strong>two identical</strong> eggs and you have access to a building with <code>n</code> floors labeled from <code>1</code> to <code>n</code>.</p>
-
-<p>You know that there exists a floor <code>f</code> where <code>0 &lt;= f &lt;= n</code> such that any egg dropped at a floor <strong>higher</strong> than <code>f</code> will <strong>break</strong>, and any egg dropped <strong>at or below</strong> floor <code>f</code> will <strong>not break</strong>.</p>
-
-<p>In each move, you may take an <strong>unbroken</strong> egg and drop it from any floor <code>x</code> (where <code>1 &lt;= x &lt;= n</code>). If the egg breaks, you can no longer use it. However, if the egg does not break, you may <strong>reuse</strong> it in future moves.</p>
-
-<p>Return <em>the <strong>minimum number of moves</strong> that you need to determine <strong>with certainty</strong> what the value of </em><code>f</code> is.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We can drop the first egg from floor 1 and the second egg from floor 2.
-If the first egg breaks, we know that f = 0.
-If the second egg breaks but the first egg didn&#39;t, we know that f = 1.
-Otherwise, if both eggs survive, we know that f = 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 100
-<strong>Output:</strong> 14
-<strong>Explanation:</strong> One optimal strategy is:
-- Drop the 1st egg at floor 9. If it breaks, we know f is between 0 and 8. Drop the 2nd egg starting from floor 1 and going up one at a time to find f within 8 more drops. Total drops is 1 + 8 = 9.
-- If the 1st egg does not break, drop the 1st egg again at floor 22. If it breaks, we know f is between 9 and 21. Drop the 2nd egg starting from floor 10 and going up one at a time to find f within 12 more drops. Total drops is 2 + 12 = 14.
-- If the 1st egg does not break again, follow a similar process dropping the 1st egg from floors 34, 45, 55, 64, 72, 79, 85, 90, 94, 97, 99, and 100.
-Regardless of the outcome, it takes at most 14 drops to determine f.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Super Egg Drop](../super-egg-drop) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is it really optimal to always drop the egg on the middle floor for each move?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we create states based on the number of unbroken eggs and floors to build our solution?
-</details>
diff --git a/problems/element-appearing-more-than-25-in-sorted-array/README.md b/problems/element-appearing-more-than-25-in-sorted-array/README.md
deleted file mode 100644
index f8ef3054c..000000000
--- a/problems/element-appearing-more-than-25-in-sorted-array/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../iterator-for-combination "Iterator for Combination")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-covered-intervals "Remove Covered Intervals")
-
-## [1287. Element Appearing More Than 25% In Sorted Array (Easy)](https://leetcode.com/problems/element-appearing-more-than-25-in-sorted-array "有序数组中出现次数超过25%的元素")
-
-<p>Given an integer array <strong>sorted</strong> in non-decreasing order, there is exactly one integer in the array that occurs more than 25% of the time, return that integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,2,6,6,6,6,7,10]
-<strong>Output:</strong> 6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,1]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Divide the array in four parts [1 - 25%] [25 - 50 %] [50 - 75 %] [75% - 100%]
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The answer should be in one of the ends of the intervals.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-In order to check which is element is the answer we can count the frequency with binarySearch.
-</details>
diff --git a/problems/elements-in-array-after-removing-and-replacing-elements/README.md b/problems/elements-in-array-after-removing-and-replacing-elements/README.md
deleted file mode 100644
index 745729049..000000000
--- a/problems/elements-in-array-after-removing-and-replacing-elements/README.md
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-airport-with-the-most-traffic "The Airport With the Most Traffic")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-words-found-in-sentences "Maximum Number of Words Found in Sentences")
-
-## [2113. Elements in Array After Removing and Replacing Elements (Medium)](https://leetcode.com/problems/elements-in-array-after-removing-and-replacing-elements "")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to find a pattern in how nums changes.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let m be the original length of nums. If time_i / m (integer division) is even, then nums is at its original size or decreasing in size. If it is odd, then it is empty, or increasing in size.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-time_i % m can be used to find how many elements are in nums at minute time_i.
-</details>
diff --git a/problems/eliminate-maximum-number-of-monsters/README.md b/problems/eliminate-maximum-number-of-monsters/README.md
deleted file mode 100644
index 96c3ed4ba..000000000
--- a/problems/eliminate-maximum-number-of-monsters/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../build-array-from-permutation "Build Array from Permutation")
-　　　　　　　　　　　　　　　　
-[Next >](../count-good-numbers "Count Good Numbers")
-
-## [1921. Eliminate Maximum Number of Monsters (Medium)](https://leetcode.com/problems/eliminate-maximum-number-of-monsters "消灭怪物的最大数量")
-
-<p>You are playing a video game where you are defending your city from a group of <code>n</code> monsters. You are given a <strong>0-indexed</strong> integer array <code>dist</code> of size <code>n</code>, where <code>dist[i]</code> is the <strong>initial distance</strong> in kilometers of the <code>i<sup>th</sup></code> monster from the city.</p>
-
-<p>The monsters walk toward the city at a <strong>constant</strong> speed. The speed of each monster is given to you in an integer array <code>speed</code> of size <code>n</code>, where <code>speed[i]</code> is the speed of the <code>i<sup>th</sup></code> monster in kilometers per minute.</p>
-
-<p>You have a weapon that, once fully charged, can eliminate a <strong>single</strong> monster. However, the weapon takes <strong>one minute</strong> to charge.The weapon is fully charged at the very start.</p>
-
-<p>You lose when any monster reaches your city. If a monster reaches the city at the exact moment the weapon is fully charged, it counts as a <strong>loss</strong>, and the game ends before you can use your weapon.</p>
-
-<p>Return <em>the <strong>maximum</strong> number of monsters that you can eliminate before you lose, or </em><code>n</code><em> if you can eliminate all the monsters before they reach the city.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> dist = [1,3,4], speed = [1,1,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-In the beginning, the distances of the monsters are [1,3,4]. You eliminate the first monster.
-After a minute, the distances of the monsters are [X,2,3]. You eliminate the second monster.
-After a minute, the distances of the monsters are [X,X,2]. You eliminate the thrid monster.
-All 3 monsters can be eliminated.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> dist = [1,1,2,3], speed = [1,1,1,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-In the beginning, the distances of the monsters are [1,1,2,3]. You eliminate the first monster.
-After a minute, the distances of the monsters are [X,0,1,2], so you lose.
-You can only eliminate 1 monster.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> dist = [3,2,4], speed = [5,3,2]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-In the beginning, the distances of the monsters are [3,2,4]. You eliminate the first monster.
-After a minute, the distances of the monsters are [X,0,2], so you lose.
-You can only eliminate 1 monster.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == dist.length == speed.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= dist[i], speed[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the amount of time it takes each monster to arrive.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the order in which the monsters will arrive.
-</details>
diff --git a/problems/elimination-game/README.md b/problems/elimination-game/README.md
deleted file mode 100644
index 2368ac99f..000000000
--- a/problems/elimination-game/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-difference "Find the Difference")
-　　　　　　　　　　　　　　　　
-[Next >](../perfect-rectangle "Perfect Rectangle")
-
-## [390. Elimination Game (Medium)](https://leetcode.com/problems/elimination-game "消除游戏")
-
-<p>You have a list <code>arr</code> of all integers in the range <code>[1, n]</code> sorted in a strictly increasing order. Apply the following algorithm on <code>arr</code>:</p>
-
-<ul>
-	<li>Starting from left to right, remove the first number and every other number afterward until you reach the end of the list.</li>
-	<li>Repeat the previous step again, but this time from right to left, remove the rightmost number and every other number from the remaining numbers.</li>
-	<li>Keep repeating the steps again, alternating left to right and right to left, until a single number remains.</li>
-</ul>
-
-<p>Given the integer <code>n</code>, return <em>the last number that remains in</em> <code>arr</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 9
-<strong>Output:</strong> 6
-<strong>Explanation:</strong>
-arr = [<u>1</u>, 2, <u>3</u>, 4, <u>5</u>, 6, <u>7</u>, 8, <u>9</u>]
-arr = [2, <u>4</u>, 6, <u>8</u>]
-arr = [<u>2</u>, 6]
-arr = [6]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/elimination-game/elimination_game.go b/problems/elimination-game/elimination_game.go
deleted file mode 100644
index 6c5120307..000000000
--- a/problems/elimination-game/elimination_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem390
diff --git a/problems/elimination-game/elimination_game_test.go b/problems/elimination-game/elimination_game_test.go
deleted file mode 100644
index 6c5120307..000000000
--- a/problems/elimination-game/elimination_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem390
diff --git a/problems/employee-bonus/README.md b/problems/employee-bonus/README.md
deleted file mode 100644
index 5caf7f8e1..000000000
--- a/problems/employee-bonus/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../out-of-boundary-paths "Out of Boundary Paths")
-　　　　　　　　　　　　　　　　
-[Next >](../get-highest-answer-rate-question "Get Highest Answer Rate Question")
-
-## [577. Employee Bonus (Easy)](https://leetcode.com/problems/employee-bonus "员工奖金")
-
-<p>Select all employee&#39;s name and bonus whose bonus is &lt; 1000.</p>
-
-<p>Table:<code>Employee </code></p>
-
-<pre>
-+-------+--------+-----------+--------+
-| empId |  name  | supervisor| salary |
-+-------+--------+-----------+--------+
-|   1   | John   |  3        | 1000   |
-|   2   | Dan    |  3        | 2000   |
-|   3   | Brad   |  null     | 4000   |
-|   4   | Thomas |  3        | 4000   |
-+-------+--------+-----------+--------+
-empId is the primary key column for this table.
-</pre>
-
-<p>Table: <code>Bonus</code></p>
-
-<pre>
-+-------+-------+
-| empId | bonus |
-+-------+-------+
-| 2     | 500   |
-| 4     | 2000  |
-+-------+-------+
-empId is the primary key column for this table.
-</pre>
-
-<p>Example ouput:</p>
-
-<pre>
-+-------+-------+
-| name  | bonus |
-+-------+-------+
-| John  | null  |
-| Dan   | 500   |
-| Brad  | null  |
-+-------+-------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Combine Two Tables](../combine-two-tables) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the EmpId in table Employee has no match in table Bonus, we consider that the corresponding bonus is null and null is smaller than 1000.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Inner join is the default join, we can solve the mismatching problem by using outer join.
-</details>
diff --git a/problems/employee-bonus/employee_bonus.sql b/problems/employee-bonus/employee_bonus.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/employee-bonus/employee_bonus.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/employee-bonus/mysql_schemas.sql b/problems/employee-bonus/mysql_schemas.sql
deleted file mode 100644
index 44404f355..000000000
--- a/problems/employee-bonus/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Employee (empId int, name varchar(255), supervisor int, salary int);
-Create table If Not Exists Bonus (empId int, bonus int);
-Truncate table Employee;
-insert into Employee (empId, name, supervisor, salary) values ('3', 'Brad', 'None', '4000');
-insert into Employee (empId, name, supervisor, salary) values ('1', 'John', '3', '1000');
-insert into Employee (empId, name, supervisor, salary) values ('2', 'Dan', '3', '2000');
-insert into Employee (empId, name, supervisor, salary) values ('4', 'Thomas', '3', '4000');
-Truncate table Bonus;
-insert into Bonus (empId, bonus) values ('2', '500');
-insert into Bonus (empId, bonus) values ('4', '2000');
diff --git a/problems/employee-free-time/README.md b/problems/employee-free-time/README.md
deleted file mode 100644
index 1353e3e34..000000000
--- a/problems/employee-free-time/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bold-words-in-string "Bold Words in String")
-　　　　　　　　　　　　　　　　
-[Next >](../find-anagram-mappings "Find Anagram Mappings")
-
-## [759. Employee Free Time (Hard)](https://leetcode.com/problems/employee-free-time "员工空闲时间")
-
-<p>We are given a list <code>schedule</code> of employees, which represents the working time for each employee.</p>
-
-<p>Each employee has a list of non-overlapping <code>Intervals</code>, and these intervals are in sorted order.</p>
-
-<p>Return the list of finite intervals representing <b>common, positive-length free time</b> for <i>all</i> employees, also in sorted order.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<b>Input:</b> schedule = [[[1,2],[5,6]],[[1,3]],[[4,10]]]
-<b>Output:</b> [[3,4]]
-<b>Explanation:</b>
-There are a total of three employees, and all common
-free time intervals would be [-inf, 1], [3, 4], [10, inf].
-We discard any intervals that contain inf as they aren&#39;t finite.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<b>Input:</b> schedule = [[[1,3],[6,7]],[[2,4]],[[2,5],[9,12]]]
-<b>Output:</b> [[5,6],[7,9]]
-</pre>
-
-<p>&nbsp;</p>
-
-<p>(Even though we are representing <code>Intervals</code> in the form <code>[x, y]</code>, the objects inside are <code>Intervals</code>, not lists or arrays. For example, <code>schedule[0][0].start = 1, schedule[0][0].end = 2</code>, and <code>schedule[0][0][0]</code> is not defined.)</p>
-
-<p>Also, we wouldn&#39;t include intervals like [5, 5] in our answer, as they have zero length.</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li><code>schedule</code> and <code>schedule[i]</code> are lists with lengths in range <code>[1, 50]</code>.</li>
-	<li><code>0 &lt;= schedule[i].start &lt; schedule[i].end &lt;= 10^8</code>.</li>
-</ol>
-
-<p><strong>NOTE:</strong>&nbsp;input types have been changed on June 17, 2019. Please reset to default code definition to get new method signature.</p>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Merge Intervals](../merge-intervals) (Medium)
-  1. [Interval List Intersections](../interval-list-intersections) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Take all the intervals and do an "events" (or "line sweep") approach - an event of (x, OPEN) increases the number of active intervals, while (x, CLOSE) decreases it.
-
-Processing in sorted order from left to right, if the number of active intervals is zero, then you crossed a region of common free time.
-</details>
diff --git a/problems/employee-free-time/employee_free_time.go b/problems/employee-free-time/employee_free_time.go
deleted file mode 100644
index 2ee80d646..000000000
--- a/problems/employee-free-time/employee_free_time.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem759
diff --git a/problems/employee-free-time/employee_free_time_test.go b/problems/employee-free-time/employee_free_time_test.go
deleted file mode 100644
index 2ee80d646..000000000
--- a/problems/employee-free-time/employee_free_time_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem759
diff --git a/problems/employee-importance/README.md b/problems/employee-importance/README.md
deleted file mode 100644
index 286dc6b8d..000000000
--- a/problems/employee-importance/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-sum-of-3-non-overlapping-subarrays "Maximum Sum of 3 Non-Overlapping Subarrays")
-　　　　　　　　　　　　　　　　
-[Next >](../stickers-to-spell-word "Stickers to Spell Word")
-
-## [690. Employee Importance (Easy)](https://leetcode.com/problems/employee-importance "员工的重要性")
-
-<p>You have a data structure of employee information, which includes the employee&#39;s unique ID, their importance value, and their direct subordinates&#39; IDs.</p>
-
-<p>You are given an array of employees <code>employees</code> where:</p>
-
-<ul>
-	<li><code>employees[i].id</code> is the ID of the <code>i<sup>th</sup></code> employee.</li>
-	<li><code>employees[i].importance</code> is the importance value of the <code>i<sup>th</sup></code> employee.</li>
-	<li><code>employees[i].subordinates</code> is a list of the IDs of the direct subordinates of the <code>i<sup>th</sup></code> employee.</li>
-</ul>
-
-<p>Given an integer <code>id</code> that represents the ID of an employee, return <em>the <strong>total</strong> importance value of this employee and all their direct subordinates</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/31/emp1-tree.jpg" style="width: 400px; height: 258px;" />
-<pre>
-<strong>Input:</strong> employees = [[1,5,[2,3]],[2,3,[]],[3,3,[]]], id = 1
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> Employee 1 has an importance value of 5 and has two direct subordinates: employee 2 and employee 3.
-They both have an importance value of 3.
-Thus, the total importance value of employee 1 is 5 + 3 + 3 = 11.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/31/emp2-tree.jpg" style="width: 362px; height: 361px;" />
-<pre>
-<strong>Input:</strong> employees = [[1,2,[5]],[5,-3,[]]], id = 5
-<strong>Output:</strong> -3
-<strong>Explanation:</strong> Employee 5 has an importance value of -3 and has no direct subordinates.
-Thus, the total importance value of employee 5 is -3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= employees.length &lt;= 2000</code></li>
-	<li><code>1 &lt;= employees[i].id &lt;= 2000</code></li>
-	<li>All <code>employees[i].id</code> are <strong>unique</strong>.</li>
-	<li><code>-100 &lt;= employees[i].importance &lt;= 100</code></li>
-	<li>One employee has at most one direct leader and may have several subordinates.</li>
-	<li>The IDs in <code>employees[i].subordinates</code> are valid IDs.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Nested List Weight Sum](../nested-list-weight-sum) (Medium)
diff --git a/problems/employee-importance/employee_importance.go b/problems/employee-importance/employee_importance.go
deleted file mode 100644
index a8c109e65..000000000
--- a/problems/employee-importance/employee_importance.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem690
diff --git a/problems/employee-importance/employee_importance.py b/problems/employee-importance/employee_importance.py
deleted file mode 100755
index aa69362ff..000000000
--- a/problems/employee-importance/employee_importance.py
+++ /dev/null
@@ -1,21 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Employee info
-class Employee:
-    def __init__(self, id, importance, subordinates):
-        # It's the unique id of each node.
-        # unique id of this employee
-        self.id = id
-        # the importance value of this employee
-        self.importance = importance
-        # the id of direct subordinates
-        self.subordinates = subordinates
-"""
-class Solution:
-    def getImportance(self, employees, id):
-        """
-        :type employees: Employee
-        :type id: int
-        :rtype: int
-        """
\ No newline at end of file
diff --git a/problems/employee-importance/employee_importance_test.go b/problems/employee-importance/employee_importance_test.go
deleted file mode 100644
index a8c109e65..000000000
--- a/problems/employee-importance/employee_importance_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem690
diff --git a/problems/employees-earning-more-than-their-managers/README.md b/problems/employees-earning-more-than-their-managers/README.md
deleted file mode 100644
index cae3f944b..000000000
--- a/problems/employees-earning-more-than-their-managers/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../consecutive-numbers "Consecutive Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../duplicate-emails "Duplicate Emails")
-
-## [181. Employees Earning More Than Their Managers (Easy)](https://leetcode.com/problems/employees-earning-more-than-their-managers "超过经理收入的员工")
-
-<p>Table: <code>Employee</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| id          | int     |
-| name        | varchar |
-| salary      | int     |
-| managerId   | int     |
-+-------------+---------+
-id is the primary key column for this table.
-Each row of this table indicates the ID of an employee, their name, salary, and the ID of their manager.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find the employees who earn more than their managers.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Employee table:
-+----+-------+--------+-----------+
-| id | name  | salary | managerId |
-+----+-------+--------+-----------+
-| 1  | Joe   | 70000  | 3         |
-| 2  | Henry | 80000  | 4         |
-| 3  | Sam   | 60000  | Null      |
-| 4  | Max   | 90000  | Null      |
-+----+-------+--------+-----------+
-<strong>Output:</strong> 
-+----------+
-| Employee |
-+----------+
-| Joe      |
-+----------+
-<strong>Explanation:</strong> Joe is the only employee who earns more than his manager.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/employees-earning-more-than-their-managers/employees_earning_more_than_their_managers.sql b/problems/employees-earning-more-than-their-managers/employees_earning_more_than_their_managers.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/employees-earning-more-than-their-managers/employees_earning_more_than_their_managers.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/employees-earning-more-than-their-managers/mysql_schemas.sql b/problems/employees-earning-more-than-their-managers/mysql_schemas.sql
deleted file mode 100644
index 47d72e79c..000000000
--- a/problems/employees-earning-more-than-their-managers/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Employee (id int, name varchar(255), salary int, managerId int);
-Truncate table Employee;
-insert into Employee (id, name, salary, managerId) values ('1', 'Joe', '70000', '3');
-insert into Employee (id, name, salary, managerId) values ('2', 'Henry', '80000', '4');
-insert into Employee (id, name, salary, managerId) values ('3', 'Sam', '60000', 'None');
-insert into Employee (id, name, salary, managerId) values ('4', 'Max', '90000', 'None');
diff --git a/problems/employees-whose-manager-left-the-company/README.md b/problems/employees-whose-manager-left-the-company/README.md
deleted file mode 100644
index f6c3b1350..000000000
--- a/problems/employees-whose-manager-left-the-company/README.md
+++ /dev/null
@@ -1,14 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-separate-numbers "Number of Ways to Separate Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../find-greatest-common-divisor-of-array "Find Greatest Common Divisor of Array")
-
-## [1978. Employees Whose Manager Left the Company (Easy)](https://leetcode.com/problems/employees-whose-manager-left-the-company "上级经理已离职的公司员工")
-
-
diff --git a/problems/employees-whose-manager-left-the-company/mysql_schemas.sql b/problems/employees-whose-manager-left-the-company/mysql_schemas.sql
deleted file mode 100644
index 8b8c69f9a..000000000
--- a/problems/employees-whose-manager-left-the-company/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Employees (employee_id int, name varchar(20), manager_id int, salary int);
-Truncate table Employees;
-insert into Employees (employee_id, name, manager_id, salary) values ('3', 'Mila', '9', '60301');
-insert into Employees (employee_id, name, manager_id, salary) values ('12', 'Antonella', 'None', '31000');
-insert into Employees (employee_id, name, manager_id, salary) values ('13', 'Emery', 'None', '67084');
-insert into Employees (employee_id, name, manager_id, salary) values ('1', 'Kalel', '11', '21241');
-insert into Employees (employee_id, name, manager_id, salary) values ('9', 'Mikaela', 'None', '50937');
-insert into Employees (employee_id, name, manager_id, salary) values ('11', 'Joziah', '6', '28485');
diff --git a/problems/employees-with-missing-information/README.md b/problems/employees-with-missing-information/README.md
deleted file mode 100644
index 87a73e013..000000000
--- a/problems/employees-with-missing-information/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-longest-valid-obstacle-course-at-each-position "Find the Longest Valid Obstacle Course at Each Position")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-searchable-numbers-in-an-unsorted-array "Binary Searchable Numbers in an Unsorted Array")
-
-## [1965. Employees With Missing Information (Easy)](https://leetcode.com/problems/employees-with-missing-information "丢失信息的雇员")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/employees-with-missing-information/mysql_schemas.sql b/problems/employees-with-missing-information/mysql_schemas.sql
deleted file mode 100644
index 811fe3cbc..000000000
--- a/problems/employees-with-missing-information/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Employees (employee_id int, name varchar(30));
-Create table If Not Exists Salaries (employee_id int, salary int);
-Truncate table Employees;
-insert into Employees (employee_id, name) values ('2', 'Crew');
-insert into Employees (employee_id, name) values ('4', 'Haven');
-insert into Employees (employee_id, name) values ('5', 'Kristian');
-Truncate table Salaries;
-insert into Salaries (employee_id, salary) values ('5', '76071');
-insert into Salaries (employee_id, salary) values ('1', '22517');
-insert into Salaries (employee_id, salary) values ('4', '63539');
diff --git a/problems/encode-and-decode-strings/README.md b/problems/encode-and-decode-strings/README.md
deleted file mode 100644
index b1676d0e4..000000000
--- a/problems/encode-and-decode-strings/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../closest-binary-search-tree-value "Closest Binary Search Tree Value")
-　　　　　　　　　　　　　　　　
-[Next >](../closest-binary-search-tree-value-ii "Closest Binary Search Tree Value II")
-
-## [271. Encode and Decode Strings (Medium)](https://leetcode.com/problems/encode-and-decode-strings "字符串的编码与解码")
-
-<p>Design an algorithm to encode <b>a list of strings</b> to <b>a string</b>. The encoded string is then sent over the network and is decoded back to the original list of strings.</p>
-
-<p>Machine 1 (sender) has the function:</p>
-
-<pre>
-string encode(vector&lt;string&gt; strs) {
-  // ... your code
-  return encoded_string;
-}</pre>
-Machine 2 (receiver) has the function:
-
-<pre>
-vector&lt;string&gt; decode(string s) {
-  //... your code
-  return strs;
-}
-</pre>
-
-<p>So Machine 1 does:</p>
-
-<pre>
-string encoded_string = encode(strs);
-</pre>
-
-<p>and Machine 2 does:</p>
-
-<pre>
-vector&lt;string&gt; strs2 = decode(encoded_string);
-</pre>
-
-<p><code>strs2</code> in Machine 2 should be the same as <code>strs</code> in Machine 1.</p>
-
-<p>Implement the <code>encode</code> and <code>decode</code> methods.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b></p>
-
-<ul>
-	<li>The string may contain any possible characters out of 256 valid ascii characters. Your algorithm should be generalized enough to work on any possible characters.</li>
-	<li>Do not use class member/global/static variables to store states. Your encode and decode algorithms should be stateless.</li>
-	<li>Do not rely on any library method such as <code>eval</code> or serialize methods. You should implement your own encode/decode algorithm.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Similar Questions
-  1. [Count and Say](../count-and-say) (Medium)
-  1. [Serialize and Deserialize Binary Tree](../serialize-and-deserialize-binary-tree) (Hard)
-  1. [String Compression](../string-compression) (Medium)
-  1. [Count Binary Substrings](../count-binary-substrings) (Easy)
diff --git a/problems/encode-and-decode-strings/encode_and_decode_strings.go b/problems/encode-and-decode-strings/encode_and_decode_strings.go
deleted file mode 100644
index 56dbdcf90..000000000
--- a/problems/encode-and-decode-strings/encode_and_decode_strings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem271
diff --git a/problems/encode-and-decode-strings/encode_and_decode_strings_test.go b/problems/encode-and-decode-strings/encode_and_decode_strings_test.go
deleted file mode 100644
index 56dbdcf90..000000000
--- a/problems/encode-and-decode-strings/encode_and_decode_strings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem271
diff --git a/problems/encode-and-decode-tinyurl/README.md b/problems/encode-and-decode-tinyurl/README.md
deleted file mode 100644
index da7d5d6bd..000000000
--- a/problems/encode-and-decode-tinyurl/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../game-play-analysis-iii "Game Play Analysis III")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-binary-tree-from-string "Construct Binary Tree from String")
-
-## [535. Encode and Decode TinyURL (Medium)](https://leetcode.com/problems/encode-and-decode-tinyurl "TinyURL 的加密与解密")
-
-<blockquote>Note: This is a companion problem to the <a href="https://leetcode.com/discuss/interview-question/system-design/" target="_blank">System Design</a> problem: <a href="https://leetcode.com/discuss/interview-question/124658/Design-a-URL-Shortener-(-TinyURL-)-System/" target="_blank">Design TinyURL</a>.</blockquote>
-
-<p>TinyURL is a URL shortening service where you enter a URL such as <code>https://leetcode.com/problems/design-tinyurl</code> and it returns a short URL such as <code>http://tinyurl.com/4e9iAk</code>. Design a class to encode a URL and decode a tiny URL.</p>
-
-<p>There is no restriction on how your encode/decode algorithm should work. You just need to ensure that a URL can be encoded to a tiny URL and the tiny URL can be decoded to the original URL.</p>
-
-<p>Implement the <code>Solution</code> class:</p>
-
-<ul>
-	<li><code>Solution()</code> Initializes the object of the system.</li>
-	<li><code>String encode(String longUrl)</code> Returns a tiny URL for the given <code>longUrl</code>.</li>
-	<li><code>String decode(String shortUrl)</code> Returns the original long URL for the given <code>shortUrl</code>. It is guaranteed that the given <code>shortUrl</code> was encoded by the same object.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> url = &quot;https://leetcode.com/problems/design-tinyurl&quot;
-<strong>Output:</strong> &quot;https://leetcode.com/problems/design-tinyurl&quot;
-
-<strong>Explanation:</strong>
-Solution obj = new Solution();
-string tiny = obj.encode(url); // returns the encoded tiny url.
-string ans = obj.decode(tiny); // returns the original url after deconding it.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= url.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>url</code> is guranteed to be a valid URL.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
diff --git a/problems/encode-and-decode-tinyurl/encode_and_decode_tinyurl.go b/problems/encode-and-decode-tinyurl/encode_and_decode_tinyurl.go
deleted file mode 100644
index 254eaecf2..000000000
--- a/problems/encode-and-decode-tinyurl/encode_and_decode_tinyurl.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem535
diff --git a/problems/encode-and-decode-tinyurl/encode_and_decode_tinyurl.py b/problems/encode-and-decode-tinyurl/encode_and_decode_tinyurl.py
deleted file mode 100755
index bf305a603..000000000
--- a/problems/encode-and-decode-tinyurl/encode_and_decode_tinyurl.py
+++ /dev/null
@@ -1,23 +0,0 @@
-#!/usr/bin/env python
-
-class Codec:
-
-    def encode(self, longUrl):
-        """Encodes a URL to a shortened URL.
-        
-        :type longUrl: str
-        :rtype: str
-        """
-        
-
-    def decode(self, shortUrl):
-        """Decodes a shortened URL to its original URL.
-        
-        :type shortUrl: str
-        :rtype: str
-        """
-        
-
-# Your Codec object will be instantiated and called as such:
-# codec = Codec()
-# codec.decode(codec.encode(url))
\ No newline at end of file
diff --git a/problems/encode-and-decode-tinyurl/encode_and_decode_tinyurl_test.go b/problems/encode-and-decode-tinyurl/encode_and_decode_tinyurl_test.go
deleted file mode 100644
index 254eaecf2..000000000
--- a/problems/encode-and-decode-tinyurl/encode_and_decode_tinyurl_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem535
diff --git a/problems/encode-n-ary-tree-to-binary-tree/README.md b/problems/encode-n-ary-tree-to-binary-tree/README.md
deleted file mode 100644
index 4ed404913..000000000
--- a/problems/encode-n-ary-tree-to-binary-tree/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flatten-a-multilevel-doubly-linked-list "Flatten a Multilevel Doubly Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../all-oone-data-structure "All O`one Data Structure")
-
-## [431. Encode N-ary Tree to Binary Tree (Hard)](https://leetcode.com/problems/encode-n-ary-tree-to-binary-tree "将 N 叉树编码为二叉树")
-
-<p>Design an algorithm to encode an N-ary tree into a binary tree and decode the binary tree to get the original N-ary tree. An N-ary tree is a rooted tree in which each node has no more than N children. Similarly, a binary tree is a rooted tree in which each node has no more than 2 children. There is no restriction on how your encode/decode algorithm should work. You just need to ensure that an N-ary tree can be encoded to a binary tree and this binary tree can be decoded to the original N-nary tree structure.</p>
-
-<p>For example, you may encode the following <code>3-ary</code> tree to a binary tree in this way:</p>
-
-<p>&nbsp;</p>
-
-<p><img src="https://assets.leetcode.com/uploads/2018/10/12/narytreebinarytreeexample.png" style="width: 100%; max-width: 640px" /></p>
-
-<p>&nbsp;</p>
-
-<p>Note that the above is just an example which <em>might or might not</em> work. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>N</code> is in the range of <code> [1, 1000]</code></li>
-	<li>Do not use class member/global/static variables to store states. Your encode and decode algorithms should be stateless.</li>
-</ol>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Serialize and Deserialize N-ary Tree](../serialize-and-deserialize-n-ary-tree) (Hard)
diff --git a/problems/encode-n-ary-tree-to-binary-tree/encode_n_ary_tree_to_binary_tree.go b/problems/encode-n-ary-tree-to-binary-tree/encode_n_ary_tree_to_binary_tree.go
deleted file mode 100644
index 3dd06cd0a..000000000
--- a/problems/encode-n-ary-tree-to-binary-tree/encode_n_ary_tree_to_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem431
diff --git a/problems/encode-n-ary-tree-to-binary-tree/encode_n_ary_tree_to_binary_tree_test.go b/problems/encode-n-ary-tree-to-binary-tree/encode_n_ary_tree_to_binary_tree_test.go
deleted file mode 100644
index 3dd06cd0a..000000000
--- a/problems/encode-n-ary-tree-to-binary-tree/encode_n_ary_tree_to_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem431
diff --git a/problems/encode-number/README.md b/problems/encode-number/README.md
deleted file mode 100644
index a64ac2153..000000000
--- a/problems/encode-number/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-score-words-formed-by-letters "Maximum Score Words Formed by Letters")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-common-region "Smallest Common Region")
-
-## [1256. Encode Number (Medium)](https://leetcode.com/problems/encode-number "加密数字")
-
-<p>Given a non-negative integer <code>num</code>, Return its <em>encoding</em> string.</p>
-
-<p>The encoding is done by converting the integer to a string using a secret function that you should deduce from the following table:</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/06/21/encode_number.png" style="width: 164px; height: 360px;" /></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 23
-<strong>Output:</strong> &quot;1000&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 107
-<strong>Output:</strong> &quot;101100&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= num &lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Convert to Base -2](../convert-to-base-2) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to find the number of binary digits returned by the function.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The pattern is to start counting from zero after determining the number of binary digits.
-</details>
diff --git a/problems/encode-string-with-shortest-length/README.md b/problems/encode-string-with-shortest-length/README.md
deleted file mode 100644
index 6cb5604f0..000000000
--- a/problems/encode-string-with-shortest-length/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../implement-rand10-using-rand7 "Implement Rand10() Using Rand7()")
-　　　　　　　　　　　　　　　　
-[Next >](../concatenated-words "Concatenated Words")
-
-## [471. Encode String with Shortest Length (Hard)](https://leetcode.com/problems/encode-string-with-shortest-length "编码最短长度的字符串")
-
-<p>Given a <b>non-empty</b> string, encode the string such that its encoded length is the shortest.</p>
-
-<p>The encoding rule is: <code>k[encoded_string]</code>, where the <i>encoded_string</i> inside the square brackets is being repeated exactly <i>k</i> times.</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li><i>k</i> will be a positive integer and encoded string will not be empty or have extra space.</li>
-	<li>You may assume that the input string contains only lowercase English letters. The string&#39;s length is at most 160.</li>
-	<li>If an encoding process does not make the string shorter, then do not encode it. If there are several solutions, return any of them is fine.</li>
-</ol>
-
-<p>&nbsp;</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-Input: &quot;aaa&quot;
-Output: &quot;aaa&quot;
-Explanation: There is no way to encode it such that it is shorter than the input string, so we do not encode it.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-Input: &quot;aaaaa&quot;
-Output: &quot;5[a]&quot;
-Explanation: &quot;5[a]&quot; is shorter than &quot;aaaaa&quot; by 1 character.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 3:</b></p>
-
-<pre>
-Input: &quot;aaaaaaaaaa&quot;
-Output: &quot;10[a]&quot;
-Explanation: &quot;a9[a]&quot; or &quot;9[a]a&quot; are also valid solutions, both of them have the same length = 5, which is the same as &quot;10[a]&quot;.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 4:</b></p>
-
-<pre>
-Input: &quot;aabcaabcd&quot;
-Output: &quot;2[aabc]d&quot;
-Explanation: &quot;aabc&quot; occurs twice, so one answer can be &quot;2[aabc]d&quot;.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 5:</b></p>
-
-<pre>
-Input: &quot;abbbabbbcabbbabbbc&quot;
-Output: &quot;2[2[abbb]c]&quot;
-Explanation: &quot;abbbabbbc&quot; occurs twice, but &quot;abbbabbbc&quot; can also be encoded to &quot;2[abbb]c&quot;, so one answer can be &quot;2[2[abbb]c]&quot;.
-</pre>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Decode String](../decode-string) (Medium)
-  1. [Number of Atoms](../number-of-atoms) (Hard)
diff --git a/problems/encode-string-with-shortest-length/encode_string_with_shortest_length.go b/problems/encode-string-with-shortest-length/encode_string_with_shortest_length.go
deleted file mode 100644
index 38533e4dd..000000000
--- a/problems/encode-string-with-shortest-length/encode_string_with_shortest_length.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem471
diff --git a/problems/encode-string-with-shortest-length/encode_string_with_shortest_length_test.go b/problems/encode-string-with-shortest-length/encode_string_with_shortest_length_test.go
deleted file mode 100644
index 38533e4dd..000000000
--- a/problems/encode-string-with-shortest-length/encode_string_with_shortest_length_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem471
diff --git a/problems/equal-rational-numbers/README.md b/problems/equal-rational-numbers/README.md
deleted file mode 100644
index c11e97a3a..000000000
--- a/problems/equal-rational-numbers/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flip-binary-tree-to-match-preorder-traversal "Flip Binary Tree To Match Preorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../k-closest-points-to-origin "K Closest Points to Origin")
-
-## [972. Equal Rational Numbers (Hard)](https://leetcode.com/problems/equal-rational-numbers "相等的有理数")
-
-<p>Given two strings <code>s</code> and <code>t</code>, each of which represents a non-negative rational number, return <code>true</code> if and only if they represent the same number. The strings may use parentheses to denote the repeating part of the rational number.</p>
-
-<p>A <strong>rational number</strong> can be represented using up to three parts: <code>&lt;IntegerPart&gt;</code>, <code>&lt;NonRepeatingPart&gt;</code>, and a <code>&lt;RepeatingPart&gt;</code>. The number will be represented in one of the following three ways:</p>
-
-<ul>
-	<li><code>&lt;IntegerPart&gt;</code>
-	<ul>
-		<li>For example, <code>12</code>, <code>0</code>, and <code>123</code>.</li>
-	</ul>
-	</li>
-	<li><code>&lt;IntegerPart&gt;<strong>&lt;.&gt;</strong>&lt;NonRepeatingPart&gt;</code>
-	<ul>
-		<li>For example, <code>0.5</code>, <code>1.</code>, <code>2.12</code>, and <code>123.0001</code>.</li>
-	</ul>
-	</li>
-	<li><code>&lt;IntegerPart&gt;<strong>&lt;.&gt;</strong>&lt;NonRepeatingPart&gt;<strong>&lt;(&gt;</strong>&lt;RepeatingPart&gt;<strong>&lt;)&gt;</strong></code>
-	<ul>
-		<li>For example, <code>0.1(6)</code>, <code>1.(9)</code>, <code>123.00(1212)</code>.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>The repeating portion of a decimal expansion is conventionally denoted within a pair of round brackets. For example:</p>
-
-<ul>
-	<li><code>1/6 = 0.16666666... = 0.1(6) = 0.1666(6) = 0.166(66)</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0.(52)&quot;, t = &quot;0.5(25)&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Because &quot;0.(52)&quot; represents 0.52525252..., and &quot;0.5(25)&quot; represents 0.52525252525..... , the strings represent the same number.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0.1666(6)&quot;, t = &quot;0.166(66)&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0.9(9)&quot;, t = &quot;1.&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> &quot;0.9(9)&quot; represents 0.999999999... repeated forever, which equals 1.  [<a href="https://en.wikipedia.org/wiki/0.999..." target="_blank">See this link for an explanation.</a>]
-&quot;1.&quot; represents the number 1, which is formed correctly: (IntegerPart) = &quot;1&quot; and (NonRepeatingPart) = &quot;&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>Each part consists only of digits.</li>
-	<li>The <code>&lt;IntegerPart&gt;</code> does not have leading zeros (except for the zero itself).</li>
-	<li><code>1 &lt;= &lt;IntegerPart&gt;.length &lt;= 4</code></li>
-	<li><code>0 &lt;= &lt;NonRepeatingPart&gt;.length &lt;= 4</code></li>
-	<li><code>1 &lt;= &lt;RepeatingPart&gt;.length &lt;= 4</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/equal-rational-numbers/equal_rational_numbers.go b/problems/equal-rational-numbers/equal_rational_numbers.go
deleted file mode 100644
index 0993d461f..000000000
--- a/problems/equal-rational-numbers/equal_rational_numbers.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem972
diff --git a/problems/equal-sum-arrays-with-minimum-number-of-operations/README.md b/problems/equal-sum-arrays-with-minimum-number-of-operations/README.md
deleted file mode 100644
index 2d888a5e5..000000000
--- a/problems/equal-sum-arrays-with-minimum-number-of-operations/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../closest-dessert-cost "Closest Dessert Cost")
-　　　　　　　　　　　　　　　　
-[Next >](../car-fleet-ii "Car Fleet II")
-
-## [1775. Equal Sum Arrays With Minimum Number of Operations (Medium)](https://leetcode.com/problems/equal-sum-arrays-with-minimum-number-of-operations "通过最少操作次数使数组的和相等")
-
-<p>You are given two arrays of integers <code>nums1</code> and <code><font face="monospace">nums2</font></code>, possibly of different lengths. The values in the arrays are between <code>1</code> and <code>6</code>, inclusive.</p>
-
-<p>In one operation, you can change any integer&#39;s value in <strong>any </strong>of the arrays to <strong>any</strong> value between <code>1</code> and <code>6</code>, inclusive.</p>
-
-<p>Return <em>the minimum number of operations required to make the sum of values in </em><code>nums1</code><em> equal to the sum of values in </em><code>nums2</code><em>.</em> Return <code>-1</code>​​​​​ if it is not possible to make the sum of the two arrays equal.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2,3,4,5,6], nums2 = [1,1,2,2,2,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You can make the sums of nums1 and nums2 equal with 3 operations. All indices are 0-indexed.
-- Change nums2[0] to 6. nums1 = [1,2,3,4,5,6], nums2 = [<u><strong>6</strong></u>,1,2,2,2,2].
-- Change nums1[5] to 1. nums1 = [1,2,3,4,5,<strong><u>1</u></strong>], nums2 = [6,1,2,2,2,2].
-- Change nums1[2] to 2. nums1 = [1,2,<strong><u>2</u></strong>,4,5,1], nums2 = [6,1,2,2,2,2].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,1,1,1,1,1,1], nums2 = [6]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There is no way to decrease the sum of nums1 or to increase the sum of nums2 to make them equal.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [6,6], nums2 = [1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You can make the sums of nums1 and nums2 equal with 3 operations. All indices are 0-indexed. 
-- Change nums1[0] to 2. nums1 = [<strong><u>2</u></strong>,6], nums2 = [1].
-- Change nums1[1] to 2. nums1 = [2,<strong><u>2</u></strong>], nums2 = [1].
-- Change nums2[0] to 4. nums1 = [2,2], nums2 = [<strong><u>4</u></strong>].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums1[i], nums2[i] &lt;= 6</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's note that we want to either decrease the sum of the array with a larger sum or increase the array's sum with the smaller sum.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can maintain the largest increase or decrease you can make in a binary search tree and each time get the maximum one.
-</details>
diff --git a/problems/equal-tree-partition/README.md b/problems/equal-tree-partition/README.md
deleted file mode 100644
index e6ca9a94b..000000000
--- a/problems/equal-tree-partition/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-width-of-binary-tree "Maximum Width of Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../strange-printer "Strange Printer")
-
-## [663. Equal Tree Partition (Medium)](https://leetcode.com/problems/equal-tree-partition "均匀树划分")
-
-<p>
-Given a binary tree with <code>n</code> nodes, your task is to check if it's possible to partition the tree to two trees which have the equal sum of values after removing <b>exactly</b> one edge on the original tree.
-</p>
-
-<p><b>Example 1:</b><br />
-<pre><b>Input:</b>     
-    5
-   / \
-  10 10
-    /  \
-   2   3
-
-<b>Output:</b> True
-<b>Explanation:</b> 
-    5
-   / 
-  10
-      
-Sum: 15
-
-   10
-  /  \
- 2    3
-
-Sum: 15
-</pre>
-</p>
-
-
-<p><b>Example 2:</b><br />
-<pre><b>Input:</b>     
-    1
-   / \
-  2  10
-    /  \
-   2   20
-
-<b>Output:</b> False
-<b>Explanation:</b> You can't split the tree into two trees with equal sum after removing exactly one edge on the tree.
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>The range of tree node value is in the range of [-100000, 100000].</li>
-<li>1 <= n <= 10000</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/equal-tree-partition/equal_tree_partition.go b/problems/equal-tree-partition/equal_tree_partition.go
deleted file mode 100644
index 0dc0df06f..000000000
--- a/problems/equal-tree-partition/equal_tree_partition.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem663
diff --git a/problems/equal-tree-partition/equal_tree_partition_test.go b/problems/equal-tree-partition/equal_tree_partition_test.go
deleted file mode 100644
index 0dc0df06f..000000000
--- a/problems/equal-tree-partition/equal_tree_partition_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem663
diff --git a/problems/erect-the-fence-ii/README.md b/problems/erect-the-fence-ii/README.md
deleted file mode 100644
index dcc541793..000000000
--- a/problems/erect-the-fence-ii/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-common-subpath "Longest Common Subpath")
-　　　　　　　　　　　　　　　　
-[Next >](../count-square-sum-triples "Count Square Sum Triples")
-
-## [1924. Erect the Fence II (Hard)](https://leetcode.com/problems/erect-the-fence-ii "安装栅栏 II")
-
-
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First, we need to note that this is a classic problem given n points you need to find the minimum enclosing circle to bind them
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Second, we need to apply a well known algorithm called welzls algorithm to help us find the minimum enclosing circle
-</details>
diff --git a/problems/erect-the-fence/README.md b/problems/erect-the-fence/README.md
deleted file mode 100644
index 3fde094a3..000000000
--- a/problems/erect-the-fence/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../customer-placing-the-largest-number-of-orders "Customer Placing the Largest Number of Orders")
-　　　　　　　　　　　　　　　　
-[Next >](../design-in-memory-file-system "Design In-Memory File System")
-
-## [587. Erect the Fence (Hard)](https://leetcode.com/problems/erect-the-fence "安装栅栏")
-
-<p>You are given an array <code>trees</code> where <code>trees[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> represents the location of a tree in the garden.</p>
-
-<p>You are asked to fence the entire garden using the minimum length of rope as it is expensive. The garden is well fenced only if <strong>all the trees are enclosed</strong>.</p>
-
-<p>Return <em>the coordinates of trees that are exactly located on the fence perimeter</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/erect2-plane.jpg" style="width: 509px; height: 500px;" />
-<pre>
-<strong>Input:</strong> points = [[1,1],[2,2],[2,0],[2,4],[3,3],[4,2]]
-<strong>Output:</strong> [[1,1],[2,0],[3,3],[2,4],[4,2]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/erect1-plane.jpg" style="width: 509px; height: 500px;" />
-<pre>
-<strong>Input:</strong> points = [[1,2],[2,2],[4,2]]
-<strong>Output:</strong> [[4,2],[2,2],[1,2]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= points.length &lt;= 3000</code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 100</code></li>
-	<li>All the given points are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/erect-the-fence/erect_the_fence.go b/problems/erect-the-fence/erect_the_fence.go
deleted file mode 100644
index 9b4c6bd11..000000000
--- a/problems/erect-the-fence/erect_the_fence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem587
diff --git a/problems/erect-the-fence/erect_the_fence_test.go b/problems/erect-the-fence/erect_the_fence_test.go
deleted file mode 100644
index 9b4c6bd11..000000000
--- a/problems/erect-the-fence/erect_the_fence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem587
diff --git a/problems/escape-a-large-maze/README.md b/problems/escape-a-large-maze/README.md
deleted file mode 100644
index 94f65508f..000000000
--- a/problems/escape-a-large-maze/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../uncrossed-lines "Uncrossed Lines")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-boomerang "Valid Boomerang")
-
-## [1036. Escape a Large Maze (Hard)](https://leetcode.com/problems/escape-a-large-maze "逃离大迷宫")
-
-<p>There is a 1 million by 1 million grid on an XY-plane, and the coordinates of each grid square are <code>(x, y)</code>.</p>
-
-<p>We start at the <code>source = [s<sub>x</sub>, s<sub>y</sub>]</code> square and want to reach the <code>target = [t<sub>x</sub>, t<sub>y</sub>]</code> square. There is also an array of <code>blocked</code> squares, where each <code>blocked[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> represents a blocked square with coordinates <code>(x<sub>i</sub>, y<sub>i</sub>)</code>.</p>
-
-<p>Each move, we can walk one square north, east, south, or west if the square is <strong>not</strong> in the array of <code>blocked</code> squares. We are also not allowed to walk outside of the grid.</p>
-
-<p>Return <code>true</code><em> if and only if it is possible to reach the </em><code>target</code><em> square from the </em><code>source</code><em> square through a sequence of valid moves</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> blocked = [[0,1],[1,0]], source = [0,0], target = [0,2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The target square is inaccessible starting from the source square because we cannot move.
-We cannot move north or east because those squares are blocked.
-We cannot move south or west because we cannot go outside of the grid.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> blocked = [], source = [0,0], target = [999999,999999]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Because there are no blocked cells, it is possible to reach the target square.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= blocked.length &lt;= 200</code></li>
-	<li><code>blocked[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt; 10<sup>6</sup></code></li>
-	<li><code>source.length == target.length == 2</code></li>
-	<li><code>0 &lt;= s<sub>x</sub>, s<sub>y</sub>, t<sub>x</sub>, t<sub>y</sub> &lt; 10<sup>6</sup></code></li>
-	<li><code>source != target</code></li>
-	<li>It is guaranteed that <code>source</code> and <code>target</code> are not blocked.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If we become stuck, there's either a loop around the source or around the target.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If there is a loop around say, the source, what is the maximum number of squares it can have?
-</details>
diff --git a/problems/escape-a-large-maze/escape_a_large_maze.go b/problems/escape-a-large-maze/escape_a_large_maze.go
deleted file mode 100644
index 575827977..000000000
--- a/problems/escape-a-large-maze/escape_a_large_maze.go
+++ /dev/null
@@ -1,56 +0,0 @@
-package problem1036
-
-var dx = []int{0, 0, 1, -1}
-var dy = []int{1, -1, 0, 0}
-
-// M is length and width of the large maze
-const M = 1e6
-
-// MAX is the largest number of points that can be enclosed by blocked
-// because of len(blocked)<=200
-const MAX = 19900
-
-func isEscapePossible(blocked [][]int, source []int, target []int) bool {
-	isBlocked := make(map[int]bool, len(blocked))
-	for _, b := range blocked {
-		x, y := b[0], b[1]
-		isBlocked[x<<32+y] = true
-	}
-	// BFS
-	isOpen := func(source, target []int) bool {
-		tx, ty := target[0], target[1]
-		//
-		points := make([][]int, 0, MAX)
-		hasSeen := make(map[int]bool, MAX)
-		//
-		sx, sy := source[0], source[1]
-		points, hasSeen[sx<<32+sy] = append(points, source), true
-		//
-		for len(points) > 0 {
-			size := len(points)
-			for i := 0; i < size; i++ {
-				px, py := points[i][0], points[i][1]
-				for k := 0; k < 4; k++ {
-					x, y := px+dx[k], py+dy[k]
-					if x == tx && y == ty {
-						return true
-					}
-					p := x<<32 + y
-					if 0 <= x && x < M &&
-						0 <= y && y < M &&
-						!isBlocked[p] &&
-						!hasSeen[p] {
-						points, hasSeen[p] = append(points, []int{x, y}), true
-					}
-				}
-			}
-			if len(hasSeen) > MAX {
-				return true
-			}
-			points = points[size:]
-		}
-		return false
-	}
-
-	return isOpen(source, target) && isOpen(target, source)
-}
diff --git a/problems/escape-the-ghosts/README.md b/problems/escape-the-ghosts/README.md
deleted file mode 100644
index 8457916e6..000000000
--- a/problems/escape-the-ghosts/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rotated-digits "Rotated Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../domino-and-tromino-tiling "Domino and Tromino Tiling")
-
-## [789. Escape The Ghosts (Medium)](https://leetcode.com/problems/escape-the-ghosts "逃脱阻碍者")
-
-<p>You are playing a simplified PAC-MAN game on an infinite 2-D grid. You start at the point <code>[0, 0]</code>, and you are given a destination point <code>target = [x<sub>target</sub>, y<sub>target</sub>]</code> that you are trying to get to. There are several ghosts on the map with their starting positions given as a 2D array <code>ghosts</code>, where <code>ghosts[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> represents the starting position of the <code>i<sup>th</sup></code> ghost. All inputs are <strong>integral coordinates</strong>.</p>
-
-<p>Each turn, you and all the ghosts may independently choose to either <strong>move 1 unit</strong> in any of the four cardinal directions: north, east, south, or west, or <strong>stay still</strong>. All actions happen <strong>simultaneously</strong>.</p>
-
-<p>You escape if and only if you can reach the target <strong>before</strong> any ghost reaches you. If you reach any square (including the target) at the <strong>same time</strong> as a ghost, it <strong>does not</strong> count as an escape.</p>
-
-<p>Return <code>true</code><em> if it is possible to escape regardless of how the ghosts move, otherwise return </em><code>false</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> ghosts = [[1,0],[0,3]], target = [0,1]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can reach the destination (0, 1) after 1 turn, while the ghosts located at (1, 0) and (0, 3) cannot catch up with you.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> ghosts = [[1,0]], target = [2,0]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> You need to reach the destination (2, 0), but the ghost at (1, 0) lies between you and the destination.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> ghosts = [[2,0]], target = [1,0]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The ghost can reach the target at the same time as you.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> ghosts = [[5,0],[-10,-2],[0,-5],[-2,-2],[-7,1]], target = [7,7]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> ghosts = [[-1,0],[0,1],[-1,0],[0,1],[-1,0]], target = [0,0]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= ghosts.length &lt;= 100</code></li>
-	<li><code>ghosts[i].length == 2</code></li>
-	<li><code>-10<sup>4</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li>There can be <strong>multiple ghosts</strong> in the same location.</li>
-	<li><code>target.length == 2</code></li>
-	<li><code>-10<sup>4</sup> &lt;= x<sub>target</sub>, y<sub>target</sub> &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/escape-the-ghosts/escape_the_ghosts.go b/problems/escape-the-ghosts/escape_the_ghosts.go
deleted file mode 100644
index 9aaa83361..000000000
--- a/problems/escape-the-ghosts/escape_the_ghosts.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem789
diff --git a/problems/escape-the-ghosts/escape_the_ghosts_test.go b/problems/escape-the-ghosts/escape_the_ghosts_test.go
deleted file mode 100644
index 9aaa83361..000000000
--- a/problems/escape-the-ghosts/escape_the_ghosts_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem789
diff --git a/problems/evaluate-boolean-expression/README.md b/problems/evaluate-boolean-expression/README.md
deleted file mode 100644
index a5787ff4f..000000000
--- a/problems/evaluate-boolean-expression/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows "Find the Kth Smallest Sum of a Matrix With Sorted Rows")
-　　　　　　　　　　　　　　　　
-[Next >](../build-an-array-with-stack-operations "Build an Array With Stack Operations")
-
-## [1440. Evaluate Boolean Expression (Medium)](https://leetcode.com/problems/evaluate-boolean-expression "计算布尔表达式的值")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/evaluate-boolean-expression/mysql_schemas.sql b/problems/evaluate-boolean-expression/mysql_schemas.sql
deleted file mode 100644
index 1b0c6f56c..000000000
--- a/problems/evaluate-boolean-expression/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create Table If Not Exists Variables (name varchar(3), value int);
-Create Table If Not Exists Expressions (left_operand varchar(3), operator ENUM('>', '<', '='), right_operand varchar(3));
-Truncate table Variables;
-insert into Variables (name, value) values ('x', '66');
-insert into Variables (name, value) values ('y', '77');
-Truncate table Expressions;
-insert into Expressions (left_operand, operator, right_operand) values ('x', '>', 'y');
-insert into Expressions (left_operand, operator, right_operand) values ('x', '<', 'y');
-insert into Expressions (left_operand, operator, right_operand) values ('x', '=', 'y');
-insert into Expressions (left_operand, operator, right_operand) values ('y', '>', 'x');
-insert into Expressions (left_operand, operator, right_operand) values ('y', '<', 'x');
-insert into Expressions (left_operand, operator, right_operand) values ('x', '=', 'x');
diff --git a/problems/evaluate-division/README.md b/problems/evaluate-division/README.md
deleted file mode 100644
index c5ec62174..000000000
--- a/problems/evaluate-division/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../random-pick-index "Random Pick Index")
-　　　　　　　　　　　　　　　　
-[Next >](../nth-digit "Nth Digit")
-
-## [399. Evaluate Division (Medium)](https://leetcode.com/problems/evaluate-division "除法求值")
-
-<p>You are given an array of variable pairs <code>equations</code> and an array of real numbers <code>values</code>, where <code>equations[i] = [A<sub>i</sub>, B<sub>i</sub>]</code> and <code>values[i]</code> represent the equation <code>A<sub>i</sub> / B<sub>i</sub> = values[i]</code>. Each <code>A<sub>i</sub></code> or <code>B<sub>i</sub></code> is a string that represents a single variable.</p>
-
-<p>You are also given some <code>queries</code>, where <code>queries[j] = [C<sub>j</sub>, D<sub>j</sub>]</code> represents the <code>j<sup>th</sup></code> query where you must find the answer for <code>C<sub>j</sub> / D<sub>j</sub> = ?</code>.</p>
-
-<p>Return <em>the answers to all queries</em>. If a single answer cannot be determined, return <code>-1.0</code>.</p>
-
-<p><strong>Note:</strong> The input is always valid. You may assume that evaluating the queries will not result in division by zero and that there is no contradiction.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> equations = [[&quot;a&quot;,&quot;b&quot;],[&quot;b&quot;,&quot;c&quot;]], values = [2.0,3.0], queries = [[&quot;a&quot;,&quot;c&quot;],[&quot;b&quot;,&quot;a&quot;],[&quot;a&quot;,&quot;e&quot;],[&quot;a&quot;,&quot;a&quot;],[&quot;x&quot;,&quot;x&quot;]]
-<strong>Output:</strong> [6.00000,0.50000,-1.00000,1.00000,-1.00000]
-<strong>Explanation:</strong> 
-Given: <em>a / b = 2.0</em>, <em>b / c = 3.0</em>
-queries are: <em>a / c = ?</em>, <em>b / a = ?</em>, <em>a / e = ?</em>, <em>a / a = ?</em>, <em>x / x = ?</em>
-return: [6.0, 0.5, -1.0, 1.0, -1.0 ]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> equations = [[&quot;a&quot;,&quot;b&quot;],[&quot;b&quot;,&quot;c&quot;],[&quot;bc&quot;,&quot;cd&quot;]], values = [1.5,2.5,5.0], queries = [[&quot;a&quot;,&quot;c&quot;],[&quot;c&quot;,&quot;b&quot;],[&quot;bc&quot;,&quot;cd&quot;],[&quot;cd&quot;,&quot;bc&quot;]]
-<strong>Output:</strong> [3.75000,0.40000,5.00000,0.20000]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> equations = [[&quot;a&quot;,&quot;b&quot;]], values = [0.5], queries = [[&quot;a&quot;,&quot;b&quot;],[&quot;b&quot;,&quot;a&quot;],[&quot;a&quot;,&quot;c&quot;],[&quot;x&quot;,&quot;y&quot;]]
-<strong>Output:</strong> [0.50000,2.00000,-1.00000,-1.00000]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= equations.length &lt;= 20</code></li>
-	<li><code>equations[i].length == 2</code></li>
-	<li><code>1 &lt;= A<sub>i</sub>.length, B<sub>i</sub>.length &lt;= 5</code></li>
-	<li><code>values.length == equations.length</code></li>
-	<li><code>0.0 &lt; values[i] &lt;= 20.0</code></li>
-	<li><code>1 &lt;= queries.length &lt;= 20</code></li>
-	<li><code>queries[i].length == 2</code></li>
-	<li><code>1 &lt;= C<sub>j</sub>.length, D<sub>j</sub>.length &lt;= 5</code></li>
-	<li><code>A<sub>i</sub>, B<sub>i</sub>, C<sub>j</sub>, D<sub>j</sub></code> consist of lower case English letters and digits.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do you recognize this as a graph problem?
-</details>
diff --git a/problems/evaluate-division/evaluate_division.go b/problems/evaluate-division/evaluate_division.go
deleted file mode 100644
index 0d1601302..000000000
--- a/problems/evaluate-division/evaluate_division.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem399
diff --git a/problems/evaluate-division/evaluate_division_test.go b/problems/evaluate-division/evaluate_division_test.go
deleted file mode 100644
index 0d1601302..000000000
--- a/problems/evaluate-division/evaluate_division_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem399
diff --git a/problems/evaluate-reverse-polish-notation/README.md b/problems/evaluate-reverse-polish-notation/README.md
deleted file mode 100644
index 43faff9a6..000000000
--- a/problems/evaluate-reverse-polish-notation/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-points-on-a-line "Max Points on a Line")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-words-in-a-string "Reverse Words in a String")
-
-## [150. Evaluate Reverse Polish Notation (Medium)](https://leetcode.com/problems/evaluate-reverse-polish-notation "逆波兰表达式求值")
-
-<p>Evaluate the value of an arithmetic expression in <a href="http://en.wikipedia.org/wiki/Reverse_Polish_notation" target="_blank">Reverse Polish Notation</a>.</p>
-
-<p>Valid operators are <code>+</code>, <code>-</code>, <code>*</code>, and <code>/</code>. Each operand may be an integer or another expression.</p>
-
-<p><strong>Note</strong> that division between two integers should truncate toward zero.</p>
-
-<p>It is guaranteed that the given RPN expression is always valid. That means the expression would always evaluate to a result, and there will not be any division by zero operation.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tokens = [&quot;2&quot;,&quot;1&quot;,&quot;+&quot;,&quot;3&quot;,&quot;*&quot;]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> ((2 + 1) * 3) = 9
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tokens = [&quot;4&quot;,&quot;13&quot;,&quot;5&quot;,&quot;/&quot;,&quot;+&quot;]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> (4 + (13 / 5)) = 6
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> tokens = [&quot;10&quot;,&quot;6&quot;,&quot;9&quot;,&quot;3&quot;,&quot;+&quot;,&quot;-11&quot;,&quot;*&quot;,&quot;/&quot;,&quot;*&quot;,&quot;17&quot;,&quot;+&quot;,&quot;5&quot;,&quot;+&quot;]
-<strong>Output:</strong> 22
-<strong>Explanation:</strong> ((10 * (6 / ((9 + 3) * -11))) + 17) + 5
-= ((10 * (6 / (12 * -11))) + 17) + 5
-= ((10 * (6 / -132)) + 17) + 5
-= ((10 * 0) + 17) + 5
-= (0 + 17) + 5
-= 17 + 5
-= 22
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= tokens.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>tokens[i]</code> is either an operator: <code>&quot;+&quot;</code>, <code>&quot;-&quot;</code>, <code>&quot;*&quot;</code>, or <code>&quot;/&quot;</code>, or an integer in the range <code>[-200, 200]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Basic Calculator](../basic-calculator) (Hard)
-  1. [Expression Add Operators](../expression-add-operators) (Hard)
diff --git a/problems/evaluate-reverse-polish-notation/evaluate_reverse_polish_notation.go b/problems/evaluate-reverse-polish-notation/evaluate_reverse_polish_notation.go
deleted file mode 100644
index e86fba761..000000000
--- a/problems/evaluate-reverse-polish-notation/evaluate_reverse_polish_notation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem150
diff --git a/problems/evaluate-reverse-polish-notation/evaluate_reverse_polish_notation_test.go b/problems/evaluate-reverse-polish-notation/evaluate_reverse_polish_notation_test.go
deleted file mode 100644
index e86fba761..000000000
--- a/problems/evaluate-reverse-polish-notation/evaluate_reverse_polish_notation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem150
diff --git a/problems/evaluate-the-bracket-pairs-of-a-string/README.md b/problems/evaluate-the-bracket-pairs-of-a-string/README.md
deleted file mode 100644
index dc2c9de26..000000000
--- a/problems/evaluate-the-bracket-pairs-of-a-string/README.md
+++ /dev/null
@@ -1,92 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-operations-to-reinitialize-a-permutation "Minimum Number of Operations to Reinitialize a Permutation")
-　　　　　　　　　　　　　　　　
-[Next >](../maximize-number-of-nice-divisors "Maximize Number of Nice Divisors")
-
-## [1807. Evaluate the Bracket Pairs of a String (Medium)](https://leetcode.com/problems/evaluate-the-bracket-pairs-of-a-string "替换字符串中的括号内容")
-
-<p>You are given a string <code>s</code> that contains some bracket pairs, with each pair containing a <strong>non-empty</strong> key.</p>
-
-<ul>
-	<li>For example, in the string <code>&quot;(name)is(age)yearsold&quot;</code>, there are <strong>two</strong> bracket pairs that contain the keys <code>&quot;name&quot;</code> and <code>&quot;age&quot;</code>.</li>
-</ul>
-
-<p>You know the values of a wide range of keys. This is represented by a 2D string array <code>knowledge</code> where each <code>knowledge[i] = [key<sub>i</sub>, value<sub>i</sub>]</code> indicates that key <code>key<sub>i</sub></code> has a value of <code>value<sub>i</sub></code>.</p>
-
-<p>You are tasked to evaluate <strong>all</strong> of the bracket pairs. When you evaluate a bracket pair that contains some key <code>key<sub>i</sub></code>, you will:</p>
-
-<ul>
-	<li>Replace <code>key<sub>i</sub></code> and the bracket pair with the key&#39;s corresponding <code>value<sub>i</sub></code>.</li>
-	<li>If you do not know the value of the key, you will replace <code>key<sub>i</sub></code> and the bracket pair with a question mark <code>&quot;?&quot;</code> (without the quotation marks).</li>
-</ul>
-
-<p>Each key will appear at most once in your <code>knowledge</code>. There will not be any nested brackets in <code>s</code>.</p>
-
-<p>Return <em>the resulting string after evaluating <strong>all</strong> of the bracket pairs.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(name)is(age)yearsold&quot;, knowledge = [[&quot;name&quot;,&quot;bob&quot;],[&quot;age&quot;,&quot;two&quot;]]
-<strong>Output:</strong> &quot;bobistwoyearsold&quot;
-<strong>Explanation:</strong>
-The key &quot;name&quot; has a value of &quot;bob&quot;, so replace &quot;(name)&quot; with &quot;bob&quot;.
-The key &quot;age&quot; has a value of &quot;two&quot;, so replace &quot;(age)&quot; with &quot;two&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;hi(name)&quot;, knowledge = [[&quot;a&quot;,&quot;b&quot;]]
-<strong>Output:</strong> &quot;hi?&quot;
-<strong>Explanation:</strong> As you do not know the value of the key &quot;name&quot;, replace &quot;(name)&quot; with &quot;?&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(a)(a)(a)aaa&quot;, knowledge = [[&quot;a&quot;,&quot;yes&quot;]]
-<strong>Output:</strong> &quot;yesyesyesaaa&quot;
-<strong>Explanation:</strong> The same key can appear multiple times.
-The key &quot;a&quot; has a value of &quot;yes&quot;, so replace all occurrences of &quot;(a)&quot; with &quot;yes&quot;.
-Notice that the &quot;a&quot;s not in a bracket pair are not evaluated.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= knowledge.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>knowledge[i].length == 2</code></li>
-	<li><code>1 &lt;= key<sub>i</sub>.length, value<sub>i</sub>.length &lt;= 10</code></li>
-	<li><code>s</code> consists of lowercase English letters and round brackets <code>&#39;(&#39;</code> and <code>&#39;)&#39;</code>.</li>
-	<li>Every open bracket <code>&#39;(&#39;</code> in <code>s</code> will have a corresponding close bracket <code>&#39;)&#39;</code>.</li>
-	<li>The key in each bracket pair of <code>s</code> will be non-empty.</li>
-	<li>There will not be any nested bracket pairs in <code>s</code>.</li>
-	<li><code>key<sub>i</sub></code> and <code>value<sub>i</sub></code> consist of lowercase English letters.</li>
-	<li>Each <code>key<sub>i</sub></code> in <code>knowledge</code> is unique.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Process pairs from right to left to handle repeats
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep track of the current enclosed string using another string
-</details>
diff --git a/problems/even-odd-tree/README.md b/problems/even-odd-tree/README.md
deleted file mode 100644
index 733b0e483..000000000
--- a/problems/even-odd-tree/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../special-array-with-x-elements-greater-than-or-equal-x "Special Array With X Elements Greater Than or Equal X")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-visible-points "Maximum Number of Visible Points")
-
-## [1609. Even Odd Tree (Medium)](https://leetcode.com/problems/even-odd-tree "奇偶树")
-
-<p>A binary tree is named <strong>Even-Odd</strong> if it meets the following conditions:</p>
-
-<ul>
-	<li>The root of the binary tree is at level index <code>0</code>, its children are at level index <code>1</code>, their children are at level index <code>2</code>, etc.</li>
-	<li>For every <strong>even-indexed</strong> level, all nodes at the level have <strong>odd</strong> integer values in <strong>strictly increasing</strong> order (from left to right).</li>
-	<li>For every <b>odd-indexed</b> level, all nodes at the level have <b>even</b> integer values in <strong>strictly decreasing</strong> order (from left to right).</li>
-</ul>
-
-<p>Given the <code>root</code> of a binary tree, <em>return </em><code>true</code><em> if the binary tree is <strong>Even-Odd</strong>, otherwise return </em><code>false</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/sample_1_1966.png" style="width: 362px; height: 229px;" />
-<pre>
-<strong>Input:</strong> root = [1,10,4,3,null,7,9,12,8,6,null,null,2]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The node values on each level are:
-Level 0: [1]
-Level 1: [10,4]
-Level 2: [3,7,9]
-Level 3: [12,8,6,2]
-Since levels 0 and 2 are all odd and increasing and levels 1 and 3 are all even and decreasing, the tree is Even-Odd.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/sample_2_1966.png" style="width: 363px; height: 167px;" />
-<pre>
-<strong>Input:</strong> root = [5,4,2,3,3,7]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The node values on each level are:
-Level 0: [5]
-Level 1: [4,2]
-Level 2: [3,3,7]
-Node values in level 2 must be in strictly increasing order, so the tree is not Even-Odd.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/22/sample_1_333_1966.png" style="width: 363px; height: 167px;" />
-<pre>
-<strong>Input:</strong> root = [5,9,1,3,5,7]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Node values in the level 1 should be even integers.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use the breadth-first search to go through all nodes layer by layer.
-</details>
diff --git a/problems/exam-room/README.md b/problems/exam-room/README.md
deleted file mode 100644
index f57444200..000000000
--- a/problems/exam-room/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-similar-strings "K-Similar Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../score-of-parentheses "Score of Parentheses")
-
-## [855. Exam Room (Medium)](https://leetcode.com/problems/exam-room "考场就座")
-
-<p>There is an exam room with <code>n</code> seats in a single row labeled from <code>0</code> to <code>n - 1</code>.</p>
-
-<p>When a student enters the room, they must sit in the seat that maximizes the distance to the closest person. If there are multiple such seats, they sit in the seat with the lowest number. If no one is in the room, then the student sits at seat number <code>0</code>.</p>
-
-<p>Design a class that simulates the mentioned exam room.</p>
-
-<p>Implement the <code>ExamRoom</code> class:</p>
-
-<ul>
-	<li><code>ExamRoom(int n)</code> Initializes the object of the exam room with the number of the seats <code>n</code>.</li>
-	<li><code>int seat()</code> Returns the label of the seat at which the next student will set.</li>
-	<li><code>void leave(int p)</code> Indicates that the student sitting at seat <code>p</code> will leave the room. It is guaranteed that there will be a student sitting at seat <code>p</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;ExamRoom&quot;, &quot;seat&quot;, &quot;seat&quot;, &quot;seat&quot;, &quot;seat&quot;, &quot;leave&quot;, &quot;seat&quot;]
-[[10], [], [], [], [], [4], []]
-<strong>Output</strong>
-[null, 0, 9, 4, 2, null, 5]
-
-<strong>Explanation</strong>
-ExamRoom examRoom = new ExamRoom(10);
-examRoom.seat(); // return 0, no one is in the room, then the student sits at seat number 0.
-examRoom.seat(); // return 9, the student sits at the last seat number 9.
-examRoom.seat(); // return 4, the student sits at the last seat number 4.
-examRoom.seat(); // return 2, the student sits at the last seat number 2.
-examRoom.leave(4);
-examRoom.seat(); // return 5, the student sits at the last seat number 5.
-
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-	<li>It is guaranteed that there is a student sitting at seat <code>p</code>.</li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>seat</code> and <code>leave</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [Maximize Distance to Closest Person](../maximize-distance-to-closest-person) (Medium)
diff --git a/problems/exam-room/exam_room.go b/problems/exam-room/exam_room.go
deleted file mode 100644
index fa1998f02..000000000
--- a/problems/exam-room/exam_room.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem855
diff --git a/problems/exam-room/exam_room_test.go b/problems/exam-room/exam_room_test.go
deleted file mode 100644
index fa1998f02..000000000
--- a/problems/exam-room/exam_room_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem855
diff --git a/problems/excel-sheet-column-number/README.md b/problems/excel-sheet-column-number/README.md
deleted file mode 100644
index dad535777..000000000
--- a/problems/excel-sheet-column-number/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-sum-iii-data-structure-design "Two Sum III - Data structure design")
-　　　　　　　　　　　　　　　　
-[Next >](../factorial-trailing-zeroes "Factorial Trailing Zeroes")
-
-## [171. Excel Sheet Column Number (Easy)](https://leetcode.com/problems/excel-sheet-column-number "Excel 表列序号")
-
-<p>Given a string <code>columnTitle</code> that represents the column title as appear in an Excel sheet, return <em>its corresponding column number</em>.</p>
-
-<p>For example:</p>
-
-<pre>
-A -&gt; 1
-B -&gt; 2
-C -&gt; 3
-...
-Z -&gt; 26
-AA -&gt; 27
-AB -&gt; 28 
-...
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> columnTitle = &quot;A&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> columnTitle = &quot;AB&quot;
-<strong>Output:</strong> 28
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> columnTitle = &quot;ZY&quot;
-<strong>Output:</strong> 701
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= columnTitle.length &lt;= 7</code></li>
-	<li><code>columnTitle</code> consists only of uppercase English letters.</li>
-	<li><code>columnTitle</code> is in the range <code>[&quot;A&quot;, &quot;FXSHRXW&quot;]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Excel Sheet Column Title](../excel-sheet-column-title) (Easy)
diff --git a/problems/excel-sheet-column-number/excel_sheet_column_number.go b/problems/excel-sheet-column-number/excel_sheet_column_number.go
deleted file mode 100644
index 23fd1dda0..000000000
--- a/problems/excel-sheet-column-number/excel_sheet_column_number.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem171
-
-func titleToNumber(s string) int {
-	ans := 0
-	for _, c := range s {
-		ans *= 26
-		ans += int(c) - 'A' + 1
-	}
-	return ans
-}
diff --git a/problems/excel-sheet-column-number/excel_sheet_column_number_test.go b/problems/excel-sheet-column-number/excel_sheet_column_number_test.go
deleted file mode 100644
index 52dcaf158..000000000
--- a/problems/excel-sheet-column-number/excel_sheet_column_number_test.go
+++ /dev/null
@@ -1,50 +0,0 @@
-package problem171
-
-import "testing"
-
-type testType struct {
-	in   string
-	want int
-}
-
-func TestTitleToNumber(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "A",
-			want: 1,
-		},
-		{
-			in:   "C",
-			want: 3,
-		},
-		{
-			in:   "Z",
-			want: 26,
-		},
-		{
-			in:   "AA",
-			want: 27,
-		},
-		{
-			in:   "AB",
-			want: 28,
-		},
-		{
-			in:   "ZY",
-			want: 701,
-		}, {
-			in:   "AAA",
-			want: 703,
-		},
-		{
-			in:   "XYZ",
-			want: 16900,
-		},
-	}
-	for _, tt := range tests {
-		got := titleToNumber(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/excel-sheet-column-title/README.md b/problems/excel-sheet-column-title/README.md
deleted file mode 100644
index 1314f666f..000000000
--- a/problems/excel-sheet-column-title/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-sum-ii-input-array-is-sorted "Two Sum II - Input array is sorted")
-　　　　　　　　　　　　　　　　
-[Next >](../majority-element "Majority Element")
-
-## [168. Excel Sheet Column Title (Easy)](https://leetcode.com/problems/excel-sheet-column-title "Excel表列名称")
-
-<p>Given an integer <code>columnNumber</code>, return <em>its corresponding column title as it appears in an Excel sheet</em>.</p>
-
-<p>For example:</p>
-
-<pre>
-A -&gt; 1
-B -&gt; 2
-C -&gt; 3
-...
-Z -&gt; 26
-AA -&gt; 27
-AB -&gt; 28 
-...
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> columnNumber = 1
-<strong>Output:</strong> &quot;A&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> columnNumber = 28
-<strong>Output:</strong> &quot;AB&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> columnNumber = 701
-<strong>Output:</strong> &quot;ZY&quot;
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> columnNumber = 2147483647
-<strong>Output:</strong> &quot;FXSHRXW&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= columnNumber &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Excel Sheet Column Number](../excel-sheet-column-number) (Easy)
diff --git a/problems/excel-sheet-column-title/excel_sheet_column_title.go b/problems/excel-sheet-column-title/excel_sheet_column_title.go
deleted file mode 100644
index 60a5e5e20..000000000
--- a/problems/excel-sheet-column-title/excel_sheet_column_title.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem168
-
-import "fmt"
-
-// Solution 1: recursive
-func convertToTitle(n int) string {
-	if n--; n < 26 {
-		return fmt.Sprintf("%c", n+'A')
-	}
-	return convertToTitle(n/26) + fmt.Sprintf("%c", n%26+'A')
-}
-
-// Solution 2: iteration
-func convertToTitle2(n int) string {
-	ans := ""
-	for ; n > 0; n /= 26 {
-		n--
-		ans = fmt.Sprintf("%c", n%26+'A') + ans
-	}
-	return ans
-}
diff --git a/problems/excel-sheet-column-title/excel_sheet_column_title_test.go b/problems/excel-sheet-column-title/excel_sheet_column_title_test.go
deleted file mode 100644
index 97e289abe..000000000
--- a/problems/excel-sheet-column-title/excel_sheet_column_title_test.go
+++ /dev/null
@@ -1,63 +0,0 @@
-package problem168
-
-import "testing"
-
-type testType struct {
-	in   int
-	want string
-}
-
-func TestConvertToTitle(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   1,
-			want: "A",
-		},
-		{
-			in:   3,
-			want: "C",
-		},
-		{
-			in:   26,
-			want: "Z",
-		},
-		{
-			in:   52,
-			want: "AZ",
-		},
-		{
-			in:   27,
-			want: "AA",
-		},
-		{
-			in:   28,
-			want: "AB",
-		},
-		{
-			in:   701,
-			want: "ZY",
-		},
-		{
-			in:   703,
-			want: "AAA",
-		},
-		{
-			in:   16900,
-			want: "XYZ",
-		},
-	}
-	// Solution 1
-	for _, tt := range tests {
-		got := convertToTitle(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-	// Solution 2
-	for _, tt := range tests {
-		got := convertToTitle2(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/exchange-seats/README.md b/problems/exchange-seats/README.md
deleted file mode 100644
index a75b1b85e..000000000
--- a/problems/exchange-seats/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-factorization "Minimum Factorization")
-　　　　　　　　　　　　　　　　
-[Next >](../swap-salary "Swap Salary")
-
-## [626. Exchange Seats (Medium)](https://leetcode.com/problems/exchange-seats "换座位")
-
-<p>Table: <code>Seat</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| id          | int     |
-| name        | varchar |
-+-------------+---------+
-id is the primary key column for this table.
-Each row of this table indicates the name and the ID of a student.
-id is a continuous increment.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to swap the seat id of every two consecutive students. If the number of students is odd, the id of the last student is not swapped.</p>
-
-<p>Return the result table ordered by <code>id</code> <strong>in ascending order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Seat table:
-+----+---------+
-| id | student |
-+----+---------+
-| 1  | Abbot   |
-| 2  | Doris   |
-| 3  | Emerson |
-| 4  | Green   |
-| 5  | Jeames  |
-+----+---------+
-<strong>Output:</strong> 
-+----+---------+
-| id | student |
-+----+---------+
-| 1  | Doris   |
-| 2  | Abbot   |
-| 3  | Green   |
-| 4  | Emerson |
-| 5  | Jeames  |
-+----+---------+
-<strong>Explanation:</strong> 
-Note that if the number of students is odd, there is no need to change the last one&#39;s seat.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/exchange-seats/exchange_seats.sql b/problems/exchange-seats/exchange_seats.sql
deleted file mode 100644
index a1ec3544b..000000000
--- a/problems/exchange-seats/exchange_seats.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT
-  s1.id,
-  COALESCE(s2.student, s1.student) AS student
-FROM
-  seat s1
-  LEFT JOIN
-  seat s2 ON ((s1.id + 1) ^ 1) - 1 = s2.id
-ORDER BY s1.id;
diff --git a/problems/exchange-seats/mysql_schemas.sql b/problems/exchange-seats/mysql_schemas.sql
deleted file mode 100644
index 3c3587aea..000000000
--- a/problems/exchange-seats/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Seat (id int, student varchar(255));
-Truncate table Seat;
-insert into Seat (id, student) values ('1', 'Abbot');
-insert into Seat (id, student) values ('2', 'Doris');
-insert into Seat (id, student) values ('3', 'Emerson');
-insert into Seat (id, student) values ('4', 'Green');
-insert into Seat (id, student) values ('5', 'Jeames');
diff --git a/problems/exclusive-time-of-functions/README.md b/problems/exclusive-time-of-functions/README.md
deleted file mode 100644
index 9c6b4fb4d..000000000
--- a/problems/exclusive-time-of-functions/README.md
+++ /dev/null
@@ -1,94 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-log-storage-system "Design Log Storage System")
-　　　　　　　　　　　　　　　　
-[Next >](../average-of-levels-in-binary-tree "Average of Levels in Binary Tree")
-
-## [636. Exclusive Time of Functions (Medium)](https://leetcode.com/problems/exclusive-time-of-functions "函数的独占时间")
-
-<p>On a <strong>single-threaded</strong> CPU, we execute a program containing <code>n</code> functions. Each function has a unique ID between <code>0</code> and <code>n-1</code>.</p>
-
-<p>Function calls are <strong>stored in a <a href="https://en.wikipedia.org/wiki/Call_stack">call stack</a></strong>: when a function call starts, its ID is pushed onto the stack, and when a function call ends, its ID is popped off the stack. The function whose ID is at the top of the stack is <strong>the current function being executed</strong>. Each time a function starts or ends, we write a log with the ID, whether it started or ended, and the timestamp.</p>
-
-<p>You are given a list <code>logs</code>, where <code>logs[i]</code> represents the <code>i<sup>th</sup></code> log message formatted as a string <code>&quot;{function_id}:{&quot;start&quot; | &quot;end&quot;}:{timestamp}&quot;</code>. For example, <code>&quot;0:start:3&quot;</code> means a function call with function ID <code>0</code> <strong>started at the beginning</strong> of timestamp <code>3</code>, and <code>&quot;1:end:2&quot;</code> means a function call with function ID <code>1</code> <strong>ended at the end</strong> of timestamp <code>2</code>. Note that a function can be called <b>multiple times, possibly recursively</b>.</p>
-
-<p>A function&#39;s <strong>exclusive time</strong> is the sum of execution times for all function calls in the program. For example, if a function is called twice, one call executing for <code>2</code> time units and another call executing for <code>1</code> time unit, the <strong>exclusive time</strong> is <code>2 + 1 = 3</code>.</p>
-
-<p>Return <em>the <strong>exclusive time</strong> of each function in an array, where the value at the </em><code>i<sup>th</sup></code><em> index represents the exclusive time for the function with ID </em><code>i</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/04/05/diag1b.png" style="width: 550px; height: 239px;" />
-<pre>
-<strong>Input:</strong> n = 2, logs = [&quot;0:start:0&quot;,&quot;1:start:2&quot;,&quot;1:end:5&quot;,&quot;0:end:6&quot;]
-<strong>Output:</strong> [3,4]
-<strong>Explanation:</strong>
-Function 0 starts at the beginning of time 0, then it executes 2 for units of time and reaches the end of time 1.
-Function 1 starts at the beginning of time 2, executes for 4 units of time, and ends at the end of time 5.
-Function 0 resumes execution at the beginning of time 6 and executes for 1 unit of time.
-So function 0 spends 2 + 1 = 3 units of total time executing, and function 1 spends 4 units of total time executing.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, logs = [&quot;0:start:0&quot;,&quot;0:start:2&quot;,&quot;0:end:5&quot;,&quot;0:start:6&quot;,&quot;0:end:6&quot;,&quot;0:end:7&quot;]
-<strong>Output:</strong> [8]
-<strong>Explanation:</strong>
-Function 0 starts at the beginning of time 0, executes for 2 units of time, and recursively calls itself.
-Function 0 (recursive call) starts at the beginning of time 2 and executes for 4 units of time.
-Function 0 (initial call) resumes execution then immediately calls itself again.
-Function 0 (2nd recursive call) starts at the beginning of time 6 and executes for 1 unit of time.
-Function 0 (initial call) resumes execution at the beginning of time 7 and executes for 1 unit of time.
-So function 0 spends 2 + 4 + 1 + 1 = 8 units of total time executing.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, logs = [&quot;0:start:0&quot;,&quot;0:start:2&quot;,&quot;0:end:5&quot;,&quot;1:start:6&quot;,&quot;1:end:6&quot;,&quot;0:end:7&quot;]
-<strong>Output:</strong> [7,1]
-<strong>Explanation:</strong>
-Function 0 starts at the beginning of time 0, executes for 2 units of time, and recursively calls itself.
-Function 0 (recursive call) starts at the beginning of time 2 and executes for 4 units of time.
-Function 0 (initial call) resumes execution then immediately calls function 1.
-Function 1 starts at the beginning of time 6, executes 1 units of time, and ends at the end of time 6.
-Function 0 resumes execution at the beginning of time 6 and executes for 2 units of time.
-So function 0 spends 2 + 4 + 1 = 7 units of total time executing, and function 1 spends 1 unit of total time executing.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, logs = [&quot;0:start:0&quot;,&quot;0:start:2&quot;,&quot;0:end:5&quot;,&quot;1:start:7&quot;,&quot;1:end:7&quot;,&quot;0:end:8&quot;]
-<strong>Output:</strong> [8,1]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, logs = [&quot;0:start:0&quot;,&quot;0:end:0&quot;]
-<strong>Output:</strong> [1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= logs.length &lt;= 500</code></li>
-	<li><code>0 &lt;= function_id &lt; n</code></li>
-	<li><code>0 &lt;= timestamp &lt;= 10<sup>9</sup></code></li>
-	<li>No two start events will happen at the same timestamp.</li>
-	<li>No two end events will happen at the same timestamp.</li>
-	<li>Each function has an <code>&quot;end&quot;</code> log for each <code>&quot;start&quot;</code> log.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
diff --git a/problems/exclusive-time-of-functions/exclusive_time_of_functions.go b/problems/exclusive-time-of-functions/exclusive_time_of_functions.go
deleted file mode 100644
index b56650067..000000000
--- a/problems/exclusive-time-of-functions/exclusive_time_of_functions.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem636
diff --git a/problems/exclusive-time-of-functions/exclusive_time_of_functions_test.go b/problems/exclusive-time-of-functions/exclusive_time_of_functions_test.go
deleted file mode 100644
index b56650067..000000000
--- a/problems/exclusive-time-of-functions/exclusive_time_of_functions_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem636
diff --git a/problems/execution-of-all-suffix-instructions-staying-in-a-grid/README.md b/problems/execution-of-all-suffix-instructions-staying-in-a-grid/README.md
deleted file mode 100644
index b462fe8ea..000000000
--- a/problems/execution-of-all-suffix-instructions-staying-in-a-grid/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../a-number-after-a-double-reversal "A Number After a Double Reversal")
-　　　　　　　　　　　　　　　　
-[Next >](../intervals-between-identical-elements "Intervals Between Identical Elements")
-
-## [2120. Execution of All Suffix Instructions Staying in a Grid (Medium)](https://leetcode.com/problems/execution-of-all-suffix-instructions-staying-in-a-grid "执行所有后缀指令")
-
-<p>There is an <code>n x n</code> grid, with the top-left cell at <code>(0, 0)</code> and the bottom-right cell at <code>(n - 1, n - 1)</code>. You are given the integer <code>n</code> and an integer array <code>startPos</code> where <code>startPos = [start<sub>row</sub>, start<sub>col</sub>]</code> indicates that a robot is initially at cell <code>(start<sub>row</sub>, start<sub>col</sub>)</code>.</p>
-
-<p>You are also given a <strong>0-indexed</strong> string <code>s</code> of length <code>m</code> where <code>s[i]</code> is the <code>i<sup>th</sup></code> instruction for the robot: <code>&#39;L&#39;</code> (move left), <code>&#39;R&#39;</code> (move right), <code>&#39;U&#39;</code> (move up), and <code>&#39;D&#39;</code> (move down).</p>
-
-<p>The robot can begin executing from any <code>i<sup>th</sup></code> instruction in <code>s</code>. It executes the instructions one by one towards the end of <code>s</code> but it stops if either of these conditions is met:</p>
-
-<ul>
-	<li>The next instruction will move the robot off the grid.</li>
-	<li>There are no more instructions left to execute.</li>
-</ul>
-
-<p>Return <em>an array</em> <code>answer</code> <em>of length</em> <code>m</code> <em>where</em> <code>answer[i]</code> <em>is <strong>the number of instructions</strong> the robot can execute if the robot <strong>begins executing from</strong> the</em> <code>i<sup>th</sup></code> <em>instruction in</em> <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/09/1.png" style="width: 145px; height: 142px;" />
-<pre>
-<strong>Input:</strong> n = 3, startPos = [0,1], s = &quot;RRDDLU&quot;
-<strong>Output:</strong> [1,5,4,3,1,0]
-<strong>Explanation:</strong> Starting from startPos and beginning execution from the i<sup>th</sup> instruction:
-- 0<sup>th</sup>: &quot;<u><strong>R</strong></u>RDDLU&quot;. Only one instruction &quot;R&quot; can be executed before it moves off the grid.
-- 1<sup>st</sup>:  &quot;<u><strong>RDDLU</strong></u>&quot;. All five instructions can be executed while it stays in the grid and ends at (1, 1).
-- 2<sup>nd</sup>:   &quot;<u><strong>DDLU</strong></u>&quot;. All four instructions can be executed while it stays in the grid and ends at (1, 0).
-- 3<sup>rd</sup>:    &quot;<u><strong>DLU</strong></u>&quot;. All three instructions can be executed while it stays in the grid and ends at (0, 0).
-- 4<sup>th</sup>:     &quot;<u><strong>L</strong></u>U&quot;. Only one instruction &quot;L&quot; can be executed before it moves off the grid.
-- 5<sup>th</sup>:      &quot;U&quot;. If moving up, it would move off the grid.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/09/2.png" style="width: 106px; height: 103px;" />
-<pre>
-<strong>Input:</strong> n = 2, startPos = [1,1], s = &quot;LURD&quot;
-<strong>Output:</strong> [4,1,0,0]
-<strong>Explanation:</strong>
-- 0<sup>th</sup>: &quot;<u><strong>LURD</strong></u>&quot;.
-- 1<sup>st</sup>:  &quot;<u><strong>U</strong></u>RD&quot;.
-- 2<sup>nd</sup>:   &quot;RD&quot;.
-- 3<sup>rd</sup>:    &quot;D&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/09/3.png" style="width: 67px; height: 64px;" />
-<pre>
-<strong>Input:</strong> n = 1, startPos = [0,0], s = &quot;LRUD&quot;
-<strong>Output:</strong> [0,0,0,0]
-<strong>Explanation:</strong> No matter which instruction the robot begins execution from, it would move off the grid.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == s.length</code></li>
-	<li><code>1 &lt;= n, m &lt;= 500</code></li>
-	<li><code>startPos.length == 2</code></li>
-	<li><code>0 &lt;= start<sub>row</sub>, start<sub>col</sub> &lt; n</code></li>
-	<li><code>s</code> consists of <code>&#39;L&#39;</code>, <code>&#39;R&#39;</code>, <code>&#39;U&#39;</code>, and <code>&#39;D&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The constraints are not very large. Can we simulate the execution by starting from each index of s?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Before any of the stopping conditions is met, stop the simulation for that index and set the answer for that index.
-</details>
diff --git a/problems/expression-add-operators/README.md b/problems/expression-add-operators/README.md
deleted file mode 100644
index eadb58d1c..000000000
--- a/problems/expression-add-operators/README.md
+++ /dev/null
@@ -1,111 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../zigzag-iterator "Zigzag Iterator")
-　　　　　　　　　　　　　　　　
-[Next >](../move-zeroes "Move Zeroes")
-
-## [282. Expression Add Operators (Hard)](https://leetcode.com/problems/expression-add-operators "给表达式添加运算符")
-
-<p>Given a string <code>num</code> that contains only digits and an integer <code>target</code>, return <em><strong>all possibilities</strong> to insert the binary operators </em><code>&#39;+&#39;</code><em>, </em><code>&#39;-&#39;</code><em>, and/or </em><code>&#39;*&#39;</code><em> between the digits of </em><code>num</code><em> so that the resultant expression evaluates to the </em><code>target</code><em> value</em>.</p>
-
-<p>Note that operands in the returned expressions <strong>should not</strong> contain leading zeros.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;123&quot;, target = 6
-<strong>Output:</strong> [&quot;1*2*3&quot;,&quot;1+2+3&quot;]
-<strong>Explanation:</strong> Both &quot;1*2*3&quot; and &quot;1+2+3&quot; evaluate to 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;232&quot;, target = 8
-<strong>Output:</strong> [&quot;2*3+2&quot;,&quot;2+3*2&quot;]
-<strong>Explanation:</strong> Both &quot;2*3+2&quot; and &quot;2+3*2&quot; evaluate to 8.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;105&quot;, target = 5
-<strong>Output:</strong> [&quot;1*0+5&quot;,&quot;10-5&quot;]
-<strong>Explanation:</strong> Both &quot;1*0+5&quot; and &quot;10-5&quot; evaluate to 5.
-Note that &quot;1-05&quot; is not a valid expression because the 5 has a leading zero.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;00&quot;, target = 0
-<strong>Output:</strong> [&quot;0*0&quot;,&quot;0+0&quot;,&quot;0-0&quot;]
-<strong>Explanation:</strong> &quot;0*0&quot;, &quot;0+0&quot;, and &quot;0-0&quot; all evaluate to 0.
-Note that &quot;00&quot; is not a valid expression because the 0 has a leading zero.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;3456237490&quot;, target = 9191
-<strong>Output:</strong> []
-<strong>Explanation:</strong> There are no expressions that can be created from &quot;3456237490&quot; to evaluate to 9191.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num.length &lt;= 10</code></li>
-	<li><code>num</code> consists of only digits.</li>
-	<li><code>-2<sup>31</sup> &lt;= target &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Evaluate Reverse Polish Notation](../evaluate-reverse-polish-notation) (Medium)
-  1. [Basic Calculator](../basic-calculator) (Hard)
-  1. [Basic Calculator II](../basic-calculator-ii) (Medium)
-  1. [Different Ways to Add Parentheses](../different-ways-to-add-parentheses) (Medium)
-  1. [Target Sum](../target-sum) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that a number can contain multiple digits.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Since the question asks us to find <b>all</b> of the valid expressions, we need a way to iterate over all of them. (<b>Hint:</b> Recursion!)
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We can keep track of the expression string and evaluate it at the very end. But that would take a lot of time. Can we keep track of the expression's value as well so as to avoid the evaluation at the very end of recursion?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Think carefully about the multiply operator. It has a higher precedence than the addition and subtraction operators. 
-
-<br> 1 + 2 = 3  <br>
-1 + 2 - 4 --> 3 - 4 --> -1 <br>
-1 + 2 - 4 * 12 --> -1 * 12 --> -12 (WRONG!) <br>
-1 + 2 - 4 * 12 --> -1 - (-4) + (-4 * 12) --> 3 + (-48) --> -45 (CORRECT!)
-</details>
-
-<details>
-<summary>Hint 5</summary>
-We simply need to keep track of the last operand in our expression and reverse it's effect on the expression's value while considering the multiply operator.
-</details>
diff --git a/problems/expression-add-operators/expression_add_operators.go b/problems/expression-add-operators/expression_add_operators.go
deleted file mode 100644
index 564a157c7..000000000
--- a/problems/expression-add-operators/expression_add_operators.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem282
diff --git a/problems/expression-add-operators/expression_add_operators_test.go b/problems/expression-add-operators/expression_add_operators_test.go
deleted file mode 100644
index 564a157c7..000000000
--- a/problems/expression-add-operators/expression_add_operators_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem282
diff --git a/problems/expressive-words/README.md b/problems/expressive-words/README.md
deleted file mode 100644
index 9e1612013..000000000
--- a/problems/expressive-words/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../soup-servings "Soup Servings")
-　　　　　　　　　　　　　　　　
-[Next >](../chalkboard-xor-game "Chalkboard XOR Game")
-
-## [809. Expressive Words (Medium)](https://leetcode.com/problems/expressive-words "情感丰富的文字")
-
-<p>Sometimes people repeat letters to represent extra feeling. For example:</p>
-
-<ul>
-	<li><code>&quot;hello&quot; -&gt; &quot;heeellooo&quot;</code></li>
-	<li><code>&quot;hi&quot; -&gt; &quot;hiiii&quot;</code></li>
-</ul>
-
-<p>In these strings like <code>&quot;heeellooo&quot;</code>, we have groups of adjacent letters that are all the same: <code>&quot;h&quot;</code>, <code>&quot;eee&quot;</code>, <code>&quot;ll&quot;</code>, <code>&quot;ooo&quot;</code>.</p>
-
-<p>You are given a string <code>s</code> and an array of query strings <code>words</code>. A query word is <strong>stretchy</strong> if it can be made to be equal to <code>s</code> by any number of applications of the following extension operation: choose a group consisting of characters <code>c</code>, and add some number of characters <code>c</code> to the group so that the size of the group is <strong>three or more</strong>.</p>
-
-<ul>
-	<li>For example, starting with <code>&quot;hello&quot;</code>, we could do an extension on the group <code>&quot;o&quot;</code> to get <code>&quot;hellooo&quot;</code>, but we cannot get <code>&quot;helloo&quot;</code> since the group <code>&quot;oo&quot;</code> has a size less than three. Also, we could do another extension like <code>&quot;ll&quot; -&gt; &quot;lllll&quot;</code> to get <code>&quot;helllllooo&quot;</code>. If <code>s = &quot;helllllooo&quot;</code>, then the query word <code>&quot;hello&quot;</code> would be <strong>stretchy</strong> because of these two extension operations: <code>query = &quot;hello&quot; -&gt; &quot;hellooo&quot; -&gt; &quot;helllllooo&quot; = s</code>.</li>
-</ul>
-
-<p>Return <em>the number of query strings that are <strong>stretchy</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;heeellooo&quot;, words = [&quot;hello&quot;, &quot;hi&quot;, &quot;helo&quot;]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 
-We can extend &quot;e&quot; and &quot;o&quot; in the word &quot;hello&quot; to get &quot;heeellooo&quot;.
-We can&#39;t extend &quot;helo&quot; to get &quot;heeellooo&quot; because the group &quot;ll&quot; is not size 3 or more.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;zzzzzyyyyy&quot;, words = [&quot;zzyy&quot;,&quot;zy&quot;,&quot;zyy&quot;]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, words.length &lt;= 100</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 100</code></li>
-	<li><code>s</code> and <code>words[i]</code> consist of lowercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/expressive-words/expressive_words.go b/problems/expressive-words/expressive_words.go
deleted file mode 100644
index 3c336700e..000000000
--- a/problems/expressive-words/expressive_words.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem809
diff --git a/problems/expressive-words/expressive_words_test.go b/problems/expressive-words/expressive_words_test.go
deleted file mode 100644
index 3c336700e..000000000
--- a/problems/expressive-words/expressive_words_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem809
diff --git a/problems/factor-combinations/README.md b/problems/factor-combinations/README.md
deleted file mode 100644
index d31d61b22..000000000
--- a/problems/factor-combinations/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../meeting-rooms-ii "Meeting Rooms II")
-　　　　　　　　　　　　　　　　
-[Next >](../verify-preorder-sequence-in-binary-search-tree "Verify Preorder Sequence in Binary Search Tree")
-
-## [254. Factor Combinations (Medium)](https://leetcode.com/problems/factor-combinations "因子的组合")
-
-<p>Numbers can be regarded as product of its factors. For example,</p>
-
-<pre>
-8 = 2 x 2 x 2;
-  = 2 x 4.
-</pre>
-
-<p>Write a function that takes an integer <i>n</i> and return all possible combinations of its factors.</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>You may assume that <i>n</i> is always positive.</li>
-	<li>Factors should be greater than 1 and less than <i>n</i>.</li>
-</ol>
-
-<p><b>Example&nbsp;1: </b></p>
-
-<pre>
-<strong>Input:</strong> <code>1</code>
-<strong>Output:</strong> []
-</pre>
-
-<p><b>Example&nbsp;2: </b></p>
-
-<pre>
-<strong>Input:</strong> <code>37</code>
-<strong>Output:</strong>[]</pre>
-
-<p><b>Example&nbsp;3: </b></p>
-
-<pre>
-<strong>Input:</strong> <code>12</code>
-<strong>Output:</strong>
-[
-  [2, 6],
-  [2, 2, 3],
-  [3, 4]
-]</pre>
-
-<p><b>Example&nbsp;4: </b></p>
-
-<pre>
-<strong>Input:</strong> <code>32</code>
-<strong>Output:</strong>
-[
-  [2, 16],
-  [2, 2, 8],
-  [2, 2, 2, 4],
-  [2, 2, 2, 2, 2],
-  [2, 4, 4],
-  [4, 8]
-]
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Combination Sum](../combination-sum) (Medium)
diff --git a/problems/factor-combinations/factor_combinations.go b/problems/factor-combinations/factor_combinations.go
deleted file mode 100644
index 75d77c0ba..000000000
--- a/problems/factor-combinations/factor_combinations.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem254
diff --git a/problems/factor-combinations/factor_combinations_test.go b/problems/factor-combinations/factor_combinations_test.go
deleted file mode 100644
index 75d77c0ba..000000000
--- a/problems/factor-combinations/factor_combinations_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem254
diff --git a/problems/factorial-trailing-zeroes/README.md b/problems/factorial-trailing-zeroes/README.md
deleted file mode 100644
index 502539b28..000000000
--- a/problems/factorial-trailing-zeroes/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../excel-sheet-column-number "Excel Sheet Column Number")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-search-tree-iterator "Binary Search Tree Iterator")
-
-## [172. Factorial Trailing Zeroes (Medium)](https://leetcode.com/problems/factorial-trailing-zeroes "阶乘后的零")
-
-<p>Given an integer <code>n</code>, return <em>the number of trailing zeroes in </em><code>n!</code>.</p>
-
-<p>Note that <code>n! = n * (n - 1) * (n - 2) * ... * 3 * 2 * 1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> 3! = 6, no trailing zero.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 5! = 120, one trailing zero.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you write a solution that works in logarithmic time complexity?</p>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Number of Digit One](../number-of-digit-one) (Hard)
-  1. [Preimage Size of Factorial Zeroes Function](../preimage-size-of-factorial-zeroes-function) (Hard)
diff --git a/problems/factorial-trailing-zeroes/factorial_trailing_zeroes.go b/problems/factorial-trailing-zeroes/factorial_trailing_zeroes.go
deleted file mode 100644
index a3908f36a..000000000
--- a/problems/factorial-trailing-zeroes/factorial_trailing_zeroes.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package problem172
-
-func trailingZeroes(n int) int {
-	if n < 5 {
-		return 0
-	}
-	return n/5 + trailingZeroes(n/5)
-}
diff --git a/problems/factorial-trailing-zeroes/factorial_trailing_zeroes_test.go b/problems/factorial-trailing-zeroes/factorial_trailing_zeroes_test.go
deleted file mode 100644
index 31a453ee2..000000000
--- a/problems/factorial-trailing-zeroes/factorial_trailing_zeroes_test.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package problem172
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestTrailingZeroes(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   3,
-			want: 0,
-		},
-		{
-			in:   5,
-			want: 1,
-		},
-		{
-			in:   7,
-			want: 1,
-		},
-		{
-			in:   8,
-			want: 1,
-		},
-		{
-			in:   10,
-			want: 2,
-		},
-		{
-			in:   12,
-			want: 2,
-		},
-		{
-			in:   25,
-			want: 6,
-		},
-	}
-	for _, tt := range tests {
-		got := trailingZeroes(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/fair-candy-swap/README.md b/problems/fair-candy-swap/README.md
deleted file mode 100644
index dbdc443d5..000000000
--- a/problems/fair-candy-swap/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../super-egg-drop "Super Egg Drop")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-binary-tree-from-preorder-and-postorder-traversal "Construct Binary Tree from Preorder and Postorder Traversal")
-
-## [888. Fair Candy Swap (Easy)](https://leetcode.com/problems/fair-candy-swap "公平的糖果交换")
-
-<p>Alice and Bob have a different total number of candies. You are given two integer arrays <code>aliceSizes</code> and <code>bobSizes</code> where <code>aliceSizes[i]</code> is the number of candies of the <code>i<sup>th</sup></code> box of candy that Alice has and <code>bobSizes[j]</code> is the number of candies of the <code>j<sup>th</sup></code> box of candy that Bob has.</p>
-
-<p>Since they are friends, they would like to exchange one candy box each so that after the exchange, they both have the same total amount of candy. The total amount of candy a person has is the sum of the number of candies in each box they have.</p>
-
-<p>Return a<em>n integer array </em><code>answer</code><em> where </em><code>answer[0]</code><em> is the number of candies in the box that Alice must exchange, and </em><code>answer[1]</code><em> is the number of candies in the box that Bob must exchange</em>. If there are multiple answers, you may <strong>return any</strong> one of them. It is guaranteed that at least one answer exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> aliceSizes = [1,1], bobSizes = [2,2]
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> aliceSizes = [1,2], bobSizes = [2,3]
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> aliceSizes = [2], bobSizes = [1,3]
-<strong>Output:</strong> [2,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= aliceSizes.length, bobSizes.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= aliceSizes[i], bobSizes[j] &lt;= 10<sup>5</sup></code></li>
-	<li>Alice and Bob have a different total number of candies.</li>
-	<li>There will be at least one valid answer for the given input.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/fair-candy-swap/fair_candy_swap.go b/problems/fair-candy-swap/fair_candy_swap.go
deleted file mode 100644
index 5ef207ded..000000000
--- a/problems/fair-candy-swap/fair_candy_swap.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem888
-
-func fairCandySwap(A []int, B []int) []int {
-	sA, sB := 0, 0
-	mB := make(map[int]bool)
-	for _, v := range A {
-		sA += v
-	}
-	for _, v := range B {
-		sB += v
-		mB[v] = true
-	}
-	for _, x := range A {
-		if mB[x+(sB-sA)/2] {
-			return []int{x, x + (sB-sA)/2}
-		}
-	}
-	return nil
-}
diff --git a/problems/fair-candy-swap/fair_candy_swap_test.go b/problems/fair-candy-swap/fair_candy_swap_test.go
deleted file mode 100644
index 125a9771b..000000000
--- a/problems/fair-candy-swap/fair_candy_swap_test.go
+++ /dev/null
@@ -1,48 +0,0 @@
-package problem888
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	a    []int
-	b    []int
-	want []int
-}
-
-func TestFairCandySwap(t *testing.T) {
-	tests := [...]testType{
-		{
-			a:    []int{1, 1},
-			b:    []int{2, 2},
-			want: []int{1, 2},
-		},
-		{
-			a:    []int{1, 2},
-			b:    []int{2, 3},
-			want: []int{1, 2},
-		},
-		{
-			a:    []int{2},
-			b:    []int{1, 3},
-			want: []int{2, 3},
-		},
-		{
-			a:    []int{1, 2, 5},
-			b:    []int{2, 4},
-			want: []int{5, 4},
-		},
-		{
-			a:    []int{1, 2, 3},
-			b:    []int{11, 15, 17},
-			want: nil,
-		},
-	}
-	for _, tt := range tests {
-		got := fairCandySwap(tt.a, tt.b)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.a, tt.b, got, tt.want)
-		}
-	}
-}
diff --git a/problems/falling-squares/README.md b/problems/falling-squares/README.md
deleted file mode 100644
index e1b6573d7..000000000
--- a/problems/falling-squares/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partition-to-k-equal-sum-subsets "Partition to K Equal Sum Subsets")
-　　　　　　　　　　　　　　　　
-[Next >](../search-in-a-binary-search-tree "Search in a Binary Search Tree")
-
-## [699. Falling Squares (Hard)](https://leetcode.com/problems/falling-squares "掉落的方块")
-
-<p>There are several squares being dropped onto the X-axis of a 2D plane.</p>
-
-<p>You are given a 2D integer array <code>positions</code> where <code>positions[i] = [left<sub>i</sub>, sideLength<sub>i</sub>]</code> represents the <code>i<sup>th</sup></code> square with a side length of <code>sideLength<sub>i</sub></code> that is dropped with its left edge aligned with X-coordinate <code>left<sub>i</sub></code>.</p>
-
-<p>Each square is dropped one at a time from a height above any landed squares. It then falls downward (negative Y direction) until it either lands <strong>on the top side of another square</strong> or <strong>on the X-axis</strong>. A square brushing the left/right side of another square does not count as landing on it. Once it lands, it freezes in place and cannot be moved.</p>
-
-<p>After each square is dropped, you must record the <strong>height of the current tallest stack of squares</strong>.</p>
-
-<p>Return <em>an integer array </em><code>ans</code><em> where </em><code>ans[i]</code><em> represents the height described above after dropping the </em><code>i<sup>th</sup></code><em> square</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/28/fallingsq1-plane.jpg" style="width: 500px; height: 505px;" />
-<pre>
-<strong>Input:</strong> positions = [[1,2],[2,3],[6,1]]
-<strong>Output:</strong> [2,5,5]
-<strong>Explanation:</strong>
-After the first drop, the tallest stack is square 1 with a height of 2.
-After the second drop, the tallest stack is squares 1 and 2 with a height of 5.
-After the third drop, the tallest stack is still squares 1 and 2 with a height of 5.
-Thus, we return an answer of [2, 5, 5].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> positions = [[100,100],[200,100]]
-<strong>Output:</strong> [100,100]
-<strong>Explanation:</strong>
-After the first drop, the tallest stack is square 1 with a height of 100.
-After the second drop, the tallest stack is either square 1 or square 2, both with heights of 100.
-Thus, we return an answer of [100, 100].
-Note that square 2 only brushes the right side of square 1, which does not count as landing on it.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= positions.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= left<sub>i</sub> &lt;= 10<sup>8</sup></code></li>
-	<li><code>1 &lt;= sideLength<sub>i</sub> &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [The Skyline Problem](../the-skyline-problem) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If positions = [[10, 20], [20, 30]], this is the same as [[1, 2], [2, 3]].  Currently, the values of positions are very large.  Can you generalize this approach so as to make the values in positions manageable?
-</details>
diff --git a/problems/falling-squares/falling_squares.go b/problems/falling-squares/falling_squares.go
deleted file mode 100644
index 8e9da725e..000000000
--- a/problems/falling-squares/falling_squares.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem699
diff --git a/problems/falling-squares/falling_squares_test.go b/problems/falling-squares/falling_squares_test.go
deleted file mode 100644
index 8e9da725e..000000000
--- a/problems/falling-squares/falling_squares_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem699
diff --git a/problems/fancy-sequence/README.md b/problems/fancy-sequence/README.md
deleted file mode 100644
index 93301026d..000000000
--- a/problems/fancy-sequence/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-sets-of-k-non-overlapping-line-segments "Number of Sets of K Non-Overlapping Line Segments")
-　　　　　　　　　　　　　　　　
-[Next >](../all-valid-triplets-that-can-represent-a-country "All Valid Triplets That Can Represent a Country")
-
-## [1622. Fancy Sequence (Hard)](https://leetcode.com/problems/fancy-sequence "奇妙序列")
-
-<p>Write an API that generates fancy sequences using the <code>append</code>, <code>addAll</code>, and <code>multAll</code> operations.</p>
-
-<p>Implement the <code>Fancy</code> class:</p>
-
-<ul>
-	<li><code>Fancy()</code> Initializes the object with an empty sequence.</li>
-	<li><code>void append(val)</code> Appends an integer <code>val</code> to the end of the sequence.</li>
-	<li><code>void addAll(inc)</code> Increments all existing values in the sequence by an integer <code>inc</code>.</li>
-	<li><code>void multAll(m)</code> Multiplies all existing values in the sequence by an integer <code>m</code>.</li>
-	<li><code>int getIndex(idx)</code> Gets the current value at index <code>idx</code> (0-indexed) of the sequence <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>. If the index is greater or equal than the length of the sequence, return <code>-1</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Fancy&quot;, &quot;append&quot;, &quot;addAll&quot;, &quot;append&quot;, &quot;multAll&quot;, &quot;getIndex&quot;, &quot;addAll&quot;, &quot;append&quot;, &quot;multAll&quot;, &quot;getIndex&quot;, &quot;getIndex&quot;, &quot;getIndex&quot;]
-[[], [2], [3], [7], [2], [0], [3], [10], [2], [0], [1], [2]]
-<strong>Output</strong>
-[null, null, null, null, null, 10, null, null, null, 26, 34, 20]
-
-<strong>Explanation</strong>
-Fancy fancy = new Fancy();
-fancy.append(2);   // fancy sequence: [2]
-fancy.addAll(3);   // fancy sequence: [2+3] -&gt; [5]
-fancy.append(7);   // fancy sequence: [5, 7]
-fancy.multAll(2);  // fancy sequence: [5*2, 7*2] -&gt; [10, 14]
-fancy.getIndex(0); // return 10
-fancy.addAll(3);   // fancy sequence: [10+3, 14+3] -&gt; [13, 17]
-fancy.append(10);  // fancy sequence: [13, 17, 10]
-fancy.multAll(2);  // fancy sequence: [13*2, 17*2, 10*2] -&gt; [26, 34, 20]
-fancy.getIndex(0); // return 26
-fancy.getIndex(1); // return 34
-fancy.getIndex(2); // return 20
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= val, inc, m &lt;= 100</code></li>
-	<li><code>0 &lt;= idx &lt;= 10<sup>5</sup></code></li>
-	<li>At most <code>10<sup>5</sup></code> calls total will be made to <code>append</code>, <code>addAll</code>, <code>multAll</code>, and <code>getIndex</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use two arrays to save the cumulative multipliers at each time point and cumulative sums adjusted by the current multiplier.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The function getIndex(idx) ask to the current value modulo 10^9+7. Use modular inverse and both arrays to calculate this value.
-</details>
diff --git a/problems/faulty-sensor/README.md b/problems/faulty-sensor/README.md
deleted file mode 100644
index 6ae59d245..000000000
--- a/problems/faulty-sensor/README.md
+++ /dev/null
@@ -1,34 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../finding-mk-average "Finding MK Average")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-operations-to-make-the-array-increasing "Minimum Operations to Make the Array Increasing")
-
-## [1826. Faulty Sensor (Easy)](https://leetcode.com/problems/faulty-sensor "有缺陷的传感器")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check for a common prefix of the two arrays.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After this common prefix, there should be one array similar to the other but shifted by one.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If both arrays can be shifted, return -1.
-</details>
diff --git a/problems/fibonacci-number/README.md b/problems/fibonacci-number/README.md
deleted file mode 100644
index 1f3969905..000000000
--- a/problems/fibonacci-number/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../most-frequent-subtree-sum "Most Frequent Subtree Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../inorder-successor-in-bst-ii "Inorder Successor in BST II")
-
-## [509. Fibonacci Number (Easy)](https://leetcode.com/problems/fibonacci-number "斐波那契数")
-
-<p>The <b>Fibonacci numbers</b>, commonly denoted <code>F(n)</code> form a sequence, called the <b>Fibonacci sequence</b>, such that each number is the sum of the two preceding ones, starting from <code>0</code> and <code>1</code>. That is,</p>
-
-<pre>
-F(0) = 0, F(1) = 1
-F(n) = F(n - 1) + F(n - 2), for n &gt; 1.
-</pre>
-
-<p>Given <code>n</code>, calculate <code>F(n)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> F(2) = F(1) + F(0) = 1 + 0 = 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> F(3) = F(2) + F(1) = 1 + 1 = 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> F(4) = F(3) + F(2) = 2 + 1 = 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 30</code></li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Climbing Stairs](../climbing-stairs) (Easy)
-  1. [Split Array into Fibonacci Sequence](../split-array-into-fibonacci-sequence) (Medium)
-  1. [Length of Longest Fibonacci Subsequence](../length-of-longest-fibonacci-subsequence) (Medium)
diff --git a/problems/fibonacci-number/fibonacci_number.go b/problems/fibonacci-number/fibonacci_number.go
deleted file mode 100644
index fc5c70161..000000000
--- a/problems/fibonacci-number/fibonacci_number.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package problem509
-
-func fib(N int) int {
-	a, b := 0, 1
-	for i := 0; i < N; i++ {
-		a, b = b, a+b
-	}
-	return a
-}
diff --git a/problems/fibonacci-number/fibonacci_number_test.go b/problems/fibonacci-number/fibonacci_number_test.go
deleted file mode 100644
index 368a379a1..000000000
--- a/problems/fibonacci-number/fibonacci_number_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem509
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestFib(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   2,
-			want: 1,
-		},
-		{
-			in:   3,
-			want: 2,
-		},
-		{
-			in:   4,
-			want: 3,
-		},
-		{
-			in:   1,
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := fib(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/filling-bookcase-shelves/README.md b/problems/filling-bookcase-shelves/README.md
deleted file mode 100644
index c6cf32c76..000000000
--- a/problems/filling-bookcase-shelves/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-in-zigzag-labelled-binary-tree "Path In Zigzag Labelled Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../parsing-a-boolean-expression "Parsing A Boolean Expression")
-
-## [1105. Filling Bookcase Shelves (Medium)](https://leetcode.com/problems/filling-bookcase-shelves "填充书架")
-
-<p>You are given an array <code>books</code> where <code>books[i] = [thickness<sub>i</sub>, height<sub>i</sub>]</code> indicates the thickness and height of the <code>i<sup>th</sup></code> book. You are also given an integer <code>shelfWidth</code>.</p>
-
-<p>We want to place these books in order onto bookcase shelves that have a total width <code>shelfWidth</code>.</p>
-
-<p>We choose some of the books to place on this shelf such that the sum of their thickness is less than or equal to <code>shelfWidth</code>, then build another level of the shelf of the bookcase so that the total height of the bookcase has increased by the maximum height of the books we just put down. We repeat this process until there are no more books to place.</p>
-
-<p>Note that at each step of the above process, the order of the books we place is the same order as the given sequence of books.</p>
-
-<ul>
-	<li>For example, if we have an ordered list of <code>5</code> books, we might place the first and second book onto the first shelf, the third book on the second shelf, and the fourth and fifth book on the last shelf.</li>
-</ul>
-
-<p>Return <em>the minimum possible height that the total bookshelf can be after placing shelves in this manner</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/06/24/shelves.png" style="height: 500px; width: 337px;" />
-<pre>
-<strong>Input:</strong> books = [[1,1],[2,3],[2,3],[1,1],[1,1],[1,1],[1,2]], shelf_width = 4
-<strong>Output:</strong> 6
-<strong>Explanation:</strong>
-The sum of the heights of the 3 shelves is 1 + 3 + 2 = 6.
-Notice that book number 2 does not have to be on the first shelf.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> books = [[1,3],[2,4],[3,2]], shelfWidth = 6
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= books.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= thickness<sub>i</sub> &lt;= shelfWidth &lt;= 1000</code></li>
-	<li><code>1 &lt;= height<sub>i</sub> &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming:  dp(i) will be the answer to the problem for books[i:].
-</details>
diff --git a/problems/filling-bookcase-shelves/filling_bookcase_shelves.go b/problems/filling-bookcase-shelves/filling_bookcase_shelves.go
deleted file mode 100644
index c9bce891f..000000000
--- a/problems/filling-bookcase-shelves/filling_bookcase_shelves.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1105
diff --git a/problems/filter-restaurants-by-vegan-friendly-price-and-distance/README.md b/problems/filter-restaurants-by-vegan-friendly-price-and-distance/README.md
deleted file mode 100644
index 8f334288f..000000000
--- a/problems/filter-restaurants-by-vegan-friendly-price-and-distance/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-palindromic-subsequences "Remove Palindromic Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance "Find the City With the Smallest Number of Neighbors at a Threshold Distance")
-
-## [1333. Filter Restaurants by Vegan-Friendly, Price and Distance (Medium)](https://leetcode.com/problems/filter-restaurants-by-vegan-friendly-price-and-distance "餐厅过滤器")
-
-<p>Given the array <code>restaurants</code> where &nbsp;<code>restaurants[i] = [id<sub>i</sub>, rating<sub>i</sub>, veganFriendly<sub>i</sub>, price<sub>i</sub>, distance<sub>i</sub>]</code>. You have to filter the restaurants using three filters.</p>
-
-<p>The <code>veganFriendly</code> filter will be either <em>true</em> (meaning you should only include restaurants with <code>veganFriendly<sub>i</sub></code> set to true)&nbsp;or <em>false</em>&nbsp;(meaning you can include any restaurant). In addition, you have the filters&nbsp;<code>maxPrice</code> and <code>maxDistance</code>&nbsp;which&nbsp;are the maximum value for price and distance of restaurants you should consider respectively.</p>
-
-<p>Return the array of restaurant <em><strong>IDs</strong></em> after filtering, ordered by <strong>rating</strong> from highest to lowest. For restaurants with the same rating, order them by <em><strong>id</strong></em> from highest to lowest. For simplicity <code>veganFriendly<sub>i</sub></code> and <code>veganFriendly</code> take value <em>1</em> when it is <em>true</em>, and <em>0</em> when it is <em>false</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> restaurants = [[1,4,1,40,10],[2,8,0,50,5],[3,8,1,30,4],[4,10,0,10,3],[5,1,1,15,1]], veganFriendly = 1, maxPrice = 50, maxDistance = 10
-<strong>Output:</strong> [3,1,5] 
-<strong>Explanation: 
-</strong>The restaurants are:
-Restaurant 1 [id=1, rating=4, veganFriendly=1, price=40, distance=10]
-Restaurant 2 [id=2, rating=8, veganFriendly=0, price=50, distance=5]
-Restaurant 3 [id=3, rating=8, veganFriendly=1, price=30, distance=4]
-Restaurant 4 [id=4, rating=10, veganFriendly=0, price=10, distance=3]
-Restaurant 5 [id=5, rating=1, veganFriendly=1, price=15, distance=1] 
-After filter restaurants with veganFriendly = 1, maxPrice = 50 and maxDistance = 10 we have restaurant 3, restaurant 1 and restaurant 5 (ordered by rating from highest to lowest). 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> restaurants = [[1,4,1,40,10],[2,8,0,50,5],[3,8,1,30,4],[4,10,0,10,3],[5,1,1,15,1]], veganFriendly = 0, maxPrice = 50, maxDistance = 10
-<strong>Output:</strong> [4,3,2,1,5]
-<strong>Explanation:</strong> The restaurants are the same as in example 1, but in this case the filter veganFriendly = 0, therefore all restaurants are considered.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> restaurants = [[1,4,1,40,10],[2,8,0,50,5],[3,8,1,30,4],[4,10,0,10,3],[5,1,1,15,1]], veganFriendly = 0, maxPrice = 30, maxDistance = 3
-<strong>Output:</strong> [4,5]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;restaurants.length &lt;= 10^4</code></li>
-	<li><code>restaurants[i].length == 5</code></li>
-	<li><code>1 &lt;=&nbsp;id<sub>i</sub>, rating<sub>i</sub>, price<sub>i</sub>, distance<sub>i </sub>&lt;= 10^5</code></li>
-	<li><code>1 &lt;=&nbsp;maxPrice,&nbsp;maxDistance &lt;= 10^5</code></li>
-	<li><code>veganFriendly<sub>i</sub></code> and&nbsp;<code>veganFriendly</code>&nbsp;are&nbsp;0 or 1.</li>
-	<li>All <code>id<sub>i</sub></code> are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do the filtering and sort as said. Note that the id may not be the index in the array.
-</details>
diff --git a/problems/final-prices-with-a-special-discount-in-a-shop/README.md b/problems/final-prices-with-a-special-discount-in-a-shop/README.md
deleted file mode 100644
index 7c6538477..000000000
--- a/problems/final-prices-with-a-special-discount-in-a-shop/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-n-nodes-after-m-nodes-of-a-linked-list "Delete N Nodes After M Nodes of a Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../subrectangle-queries "Subrectangle Queries")
-
-## [1475. Final Prices With a Special Discount in a Shop (Easy)](https://leetcode.com/problems/final-prices-with-a-special-discount-in-a-shop "商品折扣后的最终价格")
-
-<p>Given the array <code>prices</code> where <code>prices[i]</code> is the price of the <code>ith</code> item in a shop. There is a special discount for items in the shop, if you buy the <code>ith</code> item, then you will receive a discount equivalent to <code>prices[j]</code> where <code>j</code> is the <strong>minimum</strong>&nbsp;index such that <code>j &gt; i</code> and <code>prices[j] &lt;= prices[i]</code>, otherwise, you will not receive any discount at all.</p>
-
-<p><em>Return an array where the <code>ith</code> element is the final price you will pay for the <code>ith</code> item of the shop considering the special discount.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [8,4,6,2,3]
-<strong>Output:</strong> [4,2,4,2,3]
-<strong>Explanation:</strong>&nbsp;
-For item 0 with price[0]=8 you will receive a discount equivalent to prices[1]=4, therefore, the final price you will pay is 8 - 4 = 4.&nbsp;
-For item 1 with price[1]=4 you will receive a discount equivalent to prices[3]=2, therefore, the final price you will pay is 4 - 2 = 2.&nbsp;
-For item 2 with price[2]=6 you will receive a discount equivalent to prices[3]=2, therefore, the final price you will pay is 6 - 2 = 4.&nbsp;
-For items 3 and 4 you will not receive any discount at all.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [1,2,3,4,5]
-<strong>Output:</strong> [1,2,3,4,5]
-<strong>Explanation:</strong> In this case, for all items, you will not receive any discount at all.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [10,1,1,6]
-<strong>Output:</strong> [9,0,1,6]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= prices.length &lt;= 500</code></li>
-	<li><code>1 &lt;= prices[i] &lt;= 10^3</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use brute force: For the ith item in the shop with a loop find the first position j satisfying the conditions and apply the discount, otherwise, the discount is 0.
-</details>
diff --git a/problems/final-value-of-variable-after-performing-operations/README.md b/problems/final-value-of-variable-after-performing-operations/README.md
deleted file mode 100644
index acb1477c9..000000000
--- a/problems/final-value-of-variable-after-performing-operations/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-seniors-and-juniors-to-join-the-company-ii "The Number of Seniors and Juniors to Join the Company II")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-beauty-in-the-array "Sum of Beauty in the Array")
-
-## [2011. Final Value of Variable After Performing Operations (Easy)](https://leetcode.com/problems/final-value-of-variable-after-performing-operations "执行操作后的变量值")
-
-<p>There is a programming language with only <strong>four</strong> operations and <strong>one</strong> variable <code>X</code>:</p>
-
-<ul>
-	<li><code>++X</code> and <code>X++</code> <strong>increments</strong> the value of the variable <code>X</code> by <code>1</code>.</li>
-	<li><code>--X</code> and <code>X--</code> <strong>decrements</strong> the value of the variable <code>X</code> by <code>1</code>.</li>
-</ul>
-
-<p>Initially, the value of <code>X</code> is <code>0</code>.</p>
-
-<p>Given an array of strings <code>operations</code> containing a list of operations, return <em>the <strong>final </strong>value of </em><code>X</code> <em>after performing all the operations</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> operations = [&quot;--X&quot;,&quot;X++&quot;,&quot;X++&quot;]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>&nbsp;The operations are performed as follows:
-Initially, X = 0.
---X: X is decremented by 1, X =  0 - 1 = -1.
-X++: X is incremented by 1, X = -1 + 1 =  0.
-X++: X is incremented by 1, X =  0 + 1 =  1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> operations = [&quot;++X&quot;,&quot;++X&quot;,&quot;X++&quot;]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>The operations are performed as follows:
-Initially, X = 0.
-++X: X is incremented by 1, X = 0 + 1 = 1.
-++X: X is incremented by 1, X = 1 + 1 = 2.
-X++: X is incremented by 1, X = 2 + 1 = 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> operations = [&quot;X++&quot;,&quot;++X&quot;,&quot;--X&quot;,&quot;X--&quot;]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>&nbsp;The operations are performed as follows:
-Initially, X = 0.
-X++: X is incremented by 1, X = 0 + 1 = 1.
-++X: X is incremented by 1, X = 1 + 1 = 2.
---X: X is decremented by 1, X = 2 - 1 = 1.
-X--: X is decremented by 1, X = 1 - 1 = 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= operations.length &lt;= 100</code></li>
-	<li><code>operations[i]</code> will be either <code>&quot;++X&quot;</code>, <code>&quot;X++&quot;</code>, <code>&quot;--X&quot;</code>, or <code>&quot;X--&quot;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There are only two operations to keep track of.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a variable to store the value after each operation.
-</details>
diff --git a/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree/README.md b/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree/README.md
deleted file mode 100644
index 66b06bfd1..000000000
--- a/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../replace-employee-id-with-the-unique-identifier "Replace Employee ID With The Unique Identifier")
-　　　　　　　　　　　　　　　　
-[Next >](../lucky-numbers-in-a-matrix "Lucky Numbers in a Matrix")
-
-## [1379. Find a Corresponding Node of a Binary Tree in a Clone of That Tree (Medium)](https://leetcode.com/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree "找出克隆二叉树中的相同节点")
-
-<p>Given two binary trees <code>original</code> and <code>cloned</code> and given a reference to a node <code>target</code> in the original tree.</p>
-
-<p>The <code>cloned</code> tree is a <strong>copy of</strong> the <code>original</code> tree.</p>
-
-<p>Return <em>a reference to the same node</em> in the <code>cloned</code> tree.</p>
-
-<p><strong>Note</strong> that you are <strong>not allowed</strong> to change any of the two trees or the <code>target</code> node and the answer <strong>must be</strong> a reference to a node in the <code>cloned</code> tree.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/21/e1.png" style="width: 544px; height: 426px;" />
-<pre>
-<strong>Input:</strong> tree = [7,4,3,null,null,6,19], target = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> In all examples the original and cloned trees are shown. The target node is a green node from the original tree. The answer is the yellow node from the cloned tree.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/21/e2.png" style="width: 221px; height: 159px;" />
-<pre>
-<strong>Input:</strong> tree = [7], target =  7
-<strong>Output:</strong> 7
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/21/e3.png" style="width: 459px; height: 486px;" />
-<pre>
-<strong>Input:</strong> tree = [8,null,6,null,5,null,4,null,3,null,2,null,1], target = 4
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the <code>tree</code> is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li>The values of the nodes of the <code>tree</code> are unique.</li>
-	<li><code>target</code> node is a node from the <code>original</code> tree and is not <code>null</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you solve the problem if repeated values on the tree are allowed?</p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/find-a-peak-element-ii/README.md b/problems/find-a-peak-element-ii/README.md
deleted file mode 100644
index c47255627..000000000
--- a/problems/find-a-peak-element-ii/README.md
+++ /dev/null
@@ -1,92 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-earliest-and-latest-rounds-where-players-compete "The Earliest and Latest Rounds Where Players Compete")
-　　　　　　　　　　　　　　　　
-[Next >](../depth-of-bst-given-insertion-order "Depth of BST Given Insertion Order")
-
-## [1901. Find a Peak Element II (Medium)](https://leetcode.com/problems/find-a-peak-element-ii "找出顶峰元素 II")
-
-<p>A <strong>peak</strong> element in a 2D grid is an element that is <strong>strictly greater</strong> than all of its <strong>adjacent </strong>neighbors to the left, right, top, and bottom.</p>
-
-<p>Given a <strong>0-indexed</strong> <code>m x n</code> matrix <code>mat</code> where <strong>no two adjacent cells are equal</strong>, find <strong>any</strong> peak element <code>mat[i][j]</code> and return <em>the length 2 array </em><code>[i,j]</code>.</p>
-
-<p>You may assume that the entire matrix is surrounded by an <strong>outer perimeter</strong> with the value <code>-1</code> in each cell.</p>
-
-<p>You must write an algorithm that runs in <code>O(m log(n))</code> or <code>O(n log(m))</code> time.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/06/08/1.png" style="width: 206px; height: 209px;" /></p>
-
-<pre>
-<strong>Input:</strong> mat = [[1,4],[3,2]]
-<strong>Output:</strong> [0,1]
-<strong>Explanation:</strong>&nbsp;Both 3 and 4 are peak elements so [1,0] and [0,1] are both acceptable answers.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2021/06/07/3.png" style="width: 254px; height: 257px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[10,20,15],[21,30,14],[7,16,32]]
-<strong>Output:</strong> [1,1]
-<strong>Explanation:</strong>&nbsp;Both 30 and 32 are peak elements so [1,1] and [2,2] are both acceptable answers.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 500</code></li>
-	<li><code>1 &lt;= mat[i][j] &lt;= 10<sup>5</sup></code></li>
-	<li>No two adjacent cells are equal.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Find Peak Element](../find-peak-element) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's assume that the width of the array is bigger than the height, otherwise, we will split in another direction.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Split the array into three parts: central column left side and right side.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Go through the central column and two neighbor columns and look for maximum.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-If it's in the central column - this is our peak.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-If it's on the left side, run this algorithm on subarray left_side + central_column.
-</details>
-
-<details>
-<summary>Hint 6</summary>
-If it's on the right side, run this algorithm on subarray right_side + central_column
-</details>
diff --git a/problems/find-a-value-of-a-mysterious-function-closest-to-target/README.md b/problems/find-a-value-of-a-mysterious-function-closest-to-target/README.md
deleted file mode 100644
index bf5dc8ff7..000000000
--- a/problems/find-a-value-of-a-mysterious-function-closest-to-target/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-non-overlapping-substrings "Maximum Number of Non-Overlapping Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../diameter-of-n-ary-tree "Diameter of N-Ary Tree")
-
-## [1521. Find a Value of a Mysterious Function Closest to Target (Hard)](https://leetcode.com/problems/find-a-value-of-a-mysterious-function-closest-to-target "找到最接近目标值的函数值")
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/07/09/change.png" style="width: 635px; height: 312px;" /></p>
-
-<p>Winston was given the above mysterious function <code>func</code>. He has an integer array <code>arr</code> and an integer <code>target</code> and he wants to find the values <code>l</code> and <code>r</code> that make the value <code>|func(arr, l, r) - target|</code> minimum possible.</p>
-
-<p>Return <em>the minimum possible value</em> of <code>|func(arr, l, r) - target|</code>.</p>
-
-<p>Notice that <code>func</code> should be called with the values <code>l</code> and <code>r</code> where <code>0 &lt;= l, r &lt; arr.length</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [9,12,3,7,15], target = 5
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Calling func with all the pairs of [l,r] = [[0,0],[1,1],[2,2],[3,3],[4,4],[0,1],[1,2],[2,3],[3,4],[0,2],[1,3],[2,4],[0,3],[1,4],[0,4]], Winston got the following results [9,12,3,7,15,8,0,3,7,0,0,3,0,0,0]. The value closest to 5 is 7 and 3, thus the minimum difference is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1000000,1000000,1000000], target = 1
-<strong>Output:</strong> 999999
-<strong>Explanation:</strong> Winston called the func with all possible values of [l,r] and he always got 1000000, thus the min difference is 999999.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,4,8,16], target = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>0 &lt;= target &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the and value of sub-array arr[i...j] is ≥ the and value of the sub-array arr[i...j+1].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each index i using binary search or ternary search find the index j where |target - AND(arr[i...j])| is minimum, minimize this value with the global answer.
-</details>
diff --git a/problems/find-all-anagrams-in-a-string/README.md b/problems/find-all-anagrams-in-a-string/README.md
deleted file mode 100644
index d9ea68ed6..000000000
--- a/problems/find-all-anagrams-in-a-string/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-sum-iii "Path Sum III")
-　　　　　　　　　　　　　　　　
-[Next >](../ternary-expression-parser "Ternary Expression Parser")
-
-## [438. Find All Anagrams in a String (Medium)](https://leetcode.com/problems/find-all-anagrams-in-a-string "找到字符串中所有字母异位词")
-
-<p>Given two strings <code>s</code> and <code>p</code>, return <em>an array of all the start indices of </em><code>p</code><em>&#39;s anagrams in </em><code>s</code>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>An <strong>Anagram</strong> is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cbaebabacd&quot;, p = &quot;abc&quot;
-<strong>Output:</strong> [0,6]
-<strong>Explanation:</strong>
-The substring with start index = 0 is &quot;cba&quot;, which is an anagram of &quot;abc&quot;.
-The substring with start index = 6 is &quot;bac&quot;, which is an anagram of &quot;abc&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abab&quot;, p = &quot;ab&quot;
-<strong>Output:</strong> [0,1,2]
-<strong>Explanation:</strong>
-The substring with start index = 0 is &quot;ab&quot;, which is an anagram of &quot;ab&quot;.
-The substring with start index = 1 is &quot;ba&quot;, which is an anagram of &quot;ab&quot;.
-The substring with start index = 2 is &quot;ab&quot;, which is an anagram of &quot;ab&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, p.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>s</code> and <code>p</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Valid Anagram](../valid-anagram) (Easy)
-  1. [Permutation in String](../permutation-in-string) (Medium)
diff --git a/problems/find-all-anagrams-in-a-string/find_all_anagrams_in_a_string.go b/problems/find-all-anagrams-in-a-string/find_all_anagrams_in_a_string.go
deleted file mode 100644
index d5b50093f..000000000
--- a/problems/find-all-anagrams-in-a-string/find_all_anagrams_in_a_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem438
diff --git a/problems/find-all-anagrams-in-a-string/find_all_anagrams_in_a_string_test.go b/problems/find-all-anagrams-in-a-string/find_all_anagrams_in_a_string_test.go
deleted file mode 100644
index d5b50093f..000000000
--- a/problems/find-all-anagrams-in-a-string/find_all_anagrams_in_a_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem438
diff --git a/problems/find-all-duplicates-in-an-array/README.md b/problems/find-all-duplicates-in-an-array/README.md
deleted file mode 100644
index 56daee0c2..000000000
--- a/problems/find-all-duplicates-in-an-array/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../arranging-coins "Arranging Coins")
-　　　　　　　　　　　　　　　　
-[Next >](../string-compression "String Compression")
-
-## [442. Find All Duplicates in an Array (Medium)](https://leetcode.com/problems/find-all-duplicates-in-an-array "数组中重复的数据")
-
-<p>Given an integer array <code>nums</code> of length <code>n</code> where all the integers of <code>nums</code> are in the range <code>[1, n]</code> and each integer appears <strong>once</strong> or <strong>twice</strong>, return <em>an array of all the integers that appears <strong>twice</strong></em>.</p>
-
-<p>You must write an algorithm that runs in&nbsp;<code>O(n)&nbsp;</code>time and uses only constant extra space.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [4,3,2,7,8,2,3,1]
-<strong>Output:</strong> [2,3]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1,2]
-<strong>Output:</strong> [1]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [1]
-<strong>Output:</strong> []
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= n</code></li>
-	<li>Each element in <code>nums</code> appears <strong>once</strong> or <strong>twice</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [Find All Numbers Disappeared in an Array](../find-all-numbers-disappeared-in-an-array) (Easy)
diff --git a/problems/find-all-duplicates-in-an-array/find_all_duplicates_in_an_array.go b/problems/find-all-duplicates-in-an-array/find_all_duplicates_in_an_array.go
deleted file mode 100644
index 52d52ebbf..000000000
--- a/problems/find-all-duplicates-in-an-array/find_all_duplicates_in_an_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem442
diff --git a/problems/find-all-duplicates-in-an-array/find_all_duplicates_in_an_array_test.go b/problems/find-all-duplicates-in-an-array/find_all_duplicates_in_an_array_test.go
deleted file mode 100644
index 52d52ebbf..000000000
--- a/problems/find-all-duplicates-in-an-array/find_all_duplicates_in_an_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem442
diff --git a/problems/find-all-good-strings/README.md b/problems/find-all-good-strings/README.md
deleted file mode 100644
index 266e3884f..000000000
--- a/problems/find-all-good-strings/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-underground-system "Design Underground System")
-　　　　　　　　　　　　　　　　
-[Next >](../customers-who-bought-products-a-and-b-but-not-c "Customers Who Bought Products A and B but Not C")
-
-## [1397. Find All Good Strings (Hard)](https://leetcode.com/problems/find-all-good-strings "找到所有好字符串")
-
-<p>Given the strings <code>s1</code> and <code>s2</code> of size <code>n</code> and the string <code>evil</code>, return <em>the number of <strong>good</strong> strings</em>.</p>
-
-<p>A <strong>good</strong> string has size <code>n</code>, it is alphabetically greater than or equal to <code>s1</code>, it is alphabetically smaller than or equal to <code>s2</code>, and it does not contain the string <code>evil</code> as a substring. Since the answer can be a huge number, return this <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, s1 = &quot;aa&quot;, s2 = &quot;da&quot;, evil = &quot;b&quot;
-<strong>Output:</strong> 51 
-<strong>Explanation:</strong> There are 25 good strings starting with &#39;a&#39;: &quot;aa&quot;,&quot;ac&quot;,&quot;ad&quot;,...,&quot;az&quot;. Then there are 25 good strings starting with &#39;c&#39;: &quot;ca&quot;,&quot;cc&quot;,&quot;cd&quot;,...,&quot;cz&quot; and finally there is one good string starting with &#39;d&#39;: &quot;da&quot;.&nbsp;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 8, s1 = &quot;leetcode&quot;, s2 = &quot;leetgoes&quot;, evil = &quot;leet&quot;
-<strong>Output:</strong> 0 
-<strong>Explanation:</strong> All strings greater than or equal to s1 and smaller than or equal to s2 start with the prefix &quot;leet&quot;, therefore, there is not any good string.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, s1 = &quot;gx&quot;, s2 = &quot;gz&quot;, evil = &quot;x&quot;
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>s1.length == n</code></li>
-	<li><code>s2.length == n</code></li>
-	<li><code>s1 &lt;= s2</code></li>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-	<li><code>1 &lt;= evil.length &lt;= 50</code></li>
-	<li>All strings consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use DP with 4 states (pos: Int, posEvil: Int, equalToS1: Bool, equalToS2: Bool) which compute the number of valid strings of size "pos" where the maximum common suffix with string "evil" has size "posEvil". When "equalToS1" is "true", the current valid string is equal to "S1" otherwise it is greater. In a similar way when equalToS2 is "true" the current valid string is equal to "S2" otherwise it is smaller.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To update the maximum common suffix with string "evil" use KMP preprocessing.
-</details>
diff --git a/problems/find-all-groups-of-farmland/README.md b/problems/find-all-groups-of-farmland/README.md
deleted file mode 100644
index f3390da7d..000000000
--- a/problems/find-all-groups-of-farmland/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-middle-index-in-array "Find the Middle Index in Array")
-　　　　　　　　　　　　　　　　
-[Next >](../operations-on-tree "Operations on Tree")
-
-## [1992. Find All Groups of Farmland (Medium)](https://leetcode.com/problems/find-all-groups-of-farmland "找到所有的农场组")
-
-<p>You are given a <strong>0-indexed</strong> <code>m x n</code> binary matrix <code>land</code> where a <code>0</code> represents a hectare of forested land and a <code>1</code> represents a hectare of farmland.</p>
-
-<p>To keep the land organized, there are designated rectangular areas of hectares that consist <strong>entirely</strong> of farmland. These rectangular areas are called <strong>groups</strong>. No two groups are adjacent, meaning farmland in one group is <strong>not</strong> four-directionally adjacent to another farmland in a different group.</p>
-
-<p><code>land</code> can be represented by a coordinate system where the top left corner of <code>land</code> is <code>(0, 0)</code> and the bottom right corner of <code>land</code> is <code>(m-1, n-1)</code>. Find the coordinates of the top left and bottom right corner of each <strong>group</strong> of farmland. A <strong>group</strong> of farmland with a top left corner at <code>(r<sub>1</sub>, c<sub>1</sub>)</code> and a bottom right corner at <code>(r<sub>2</sub>, c<sub>2</sub>)</code> is represented by the 4-length array <code>[r<sub>1</sub>, c<sub>1</sub>, r<sub>2</sub>, c<sub>2</sub>].</code></p>
-
-<p>Return <em>a 2D array containing the 4-length arrays described above for each <strong>group</strong> of farmland in </em><code>land</code><em>. If there are no groups of farmland, return an empty array. You may return the answer in <strong>any order</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/27/screenshot-2021-07-27-at-12-23-15-copy-of-diagram-drawio-diagrams-net.png" style="width: 300px; height: 300px;" />
-<pre>
-<strong>Input:</strong> land = [[1,0,0],[0,1,1],[0,1,1]]
-<strong>Output:</strong> [[0,0,0,0],[1,1,2,2]]
-<strong>Explanation:</strong>
-The first group has a top left corner at land[0][0] and a bottom right corner at land[0][0].
-The second group has a top left corner at land[1][1] and a bottom right corner at land[2][2].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/27/screenshot-2021-07-27-at-12-30-26-copy-of-diagram-drawio-diagrams-net.png" style="width: 200px; height: 200px;" />
-<pre>
-<strong>Input:</strong> land = [[1,1],[1,1]]
-<strong>Output:</strong> [[0,0,1,1]]
-<strong>Explanation:</strong>
-The first group has a top left corner at land[0][0] and a bottom right corner at land[1][1].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/27/screenshot-2021-07-27-at-12-32-24-copy-of-diagram-drawio-diagrams-net.png" style="width: 100px; height: 100px;" />
-<pre>
-<strong>Input:</strong> land = [[0]]
-<strong>Output:</strong> []
-<strong>Explanation:</strong>
-There are no groups of farmland.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == land.length</code></li>
-	<li><code>n == land[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 300</code></li>
-	<li><code>land</code> consists of only <code>0</code>&#39;s and <code>1</code>&#39;s.</li>
-	<li>Groups of farmland are <strong>rectangular</strong> in shape.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since every group of farmland is rectangular, the top left corner of each group will have the smallest x-coordinate and y-coordinate of any farmland in the group.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Similarly, the bootm right corner of each group will have the largest x-coordinate and y-coordinate of any farmland in the group.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use DFS to traverse through different groups of farmlands and keep track of the smallest and largest x-coordinate and y-coordinates you have seen in each group.
-</details>
diff --git a/problems/find-all-lonely-numbers-in-the-array/README.md b/problems/find-all-lonely-numbers-in-the-array/README.md
deleted file mode 100644
index 3ab667e3d..000000000
--- a/problems/find-all-lonely-numbers-in-the-array/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rearrange-array-elements-by-sign "Rearrange Array Elements by Sign")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-good-people-based-on-statements "Maximum Good People Based on Statements")
-
-## [2150. Find All Lonely Numbers in the Array (Medium)](https://leetcode.com/problems/find-all-lonely-numbers-in-the-array "找出数组中的所有孤独数字")
-
-<p>You are given an integer array <code>nums</code>. A number <code>x</code> is <strong>lonely</strong> when it appears only <strong>once</strong>, and no <strong>adjacent</strong> numbers (i.e. <code>x + 1</code> and <code>x - 1)</code> appear in the array.</p>
-
-<p>Return <em><strong>all</strong> lonely numbers in </em><code>nums</code>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,6,5,8]
-<strong>Output:</strong> [10,8]
-<strong>Explanation:</strong> 
-- 10 is a lonely number since it appears exactly once and 9 and 11 does not appear in nums.
-- 8 is a lonely number since it appears exactly once and 7 and 9 does not appear in nums.
-- 5 is not a lonely number since 6 appears in nums and vice versa.
-Hence, the lonely numbers in nums are [10, 8].
-Note that [8, 10] may also be returned.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,5,3]
-<strong>Output:</strong> [1,5]
-<strong>Explanation:</strong> 
-- 1 is a lonely number since it appears exactly once and 0 and 2 does not appear in nums.
-- 5 is a lonely number since it appears exactly once and 4 and 6 does not appear in nums.
-- 3 is not a lonely number since it appears twice.
-Hence, the lonely numbers in nums are [1, 5].
-Note that [5, 1] may also be returned.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For a given element x, how can you quickly check if x - 1 and x + 1 are present in the array without reiterating through the entire array?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a set or a hash map.
-</details>
diff --git a/problems/find-all-numbers-disappeared-in-an-array/README.md b/problems/find-all-numbers-disappeared-in-an-array/README.md
deleted file mode 100644
index c05834526..000000000
--- a/problems/find-all-numbers-disappeared-in-an-array/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-boomerangs "Number of Boomerangs")
-　　　　　　　　　　　　　　　　
-[Next >](../serialize-and-deserialize-bst "Serialize and Deserialize BST")
-
-## [448. Find All Numbers Disappeared in an Array (Easy)](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array "找到所有数组中消失的数字")
-
-<p>Given an array <code>nums</code> of <code>n</code> integers where <code>nums[i]</code> is in the range <code>[1, n]</code>, return <em>an array of all the integers in the range</em> <code>[1, n]</code> <em>that do not appear in</em> <code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [4,3,2,7,8,2,3,1]
-<strong>Output:</strong> [5,6]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1]
-<strong>Output:</strong> [2]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= n</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you do it without extra space and in <code>O(n)</code> runtime? You may assume the returned list does not count as extra space.</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [First Missing Positive](../first-missing-positive) (Hard)
-  1. [Find All Duplicates in an Array](../find-all-duplicates-in-an-array) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-This is a really easy problem if you decide to use additional memory. For those trying to write an initial solution using additional memory, think <b>counters!</b>
-</details>
-
-<details>
-<summary>Hint 2</summary>
-However, the trick really is to not use any additional space than what is already available to use. Sometimes, multiple passes over the input array help find the solution. However, there's an interesting piece of information in this problem that makes it easy to re-use the input array itself for the solution.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The problem specifies that the numbers in the array will be in the range [1, n] where n is the number of elements in the array. Can we use this information and modify the array in-place somehow to find what we need?
-</details>
diff --git a/problems/find-all-numbers-disappeared-in-an-array/find_all_numbers_disappeared_in_an_array.go b/problems/find-all-numbers-disappeared-in-an-array/find_all_numbers_disappeared_in_an_array.go
deleted file mode 100644
index 44a7c54e6..000000000
--- a/problems/find-all-numbers-disappeared-in-an-array/find_all_numbers_disappeared_in_an_array.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem448
-
-func findDisappearedNumbers(nums []int) []int {
-	max, count := len(nums), 0
-	s := make([]bool, max)
-	for _, v := range nums {
-		s[v-1] = true
-	}
-	for i := 1; i <= max; i++ {
-		if !s[i-1] {
-			nums[count] = i
-			count++
-		}
-	}
-	return nums[:count]
-}
diff --git a/problems/find-all-numbers-disappeared-in-an-array/find_all_numbers_disappeared_in_an_array_test.go b/problems/find-all-numbers-disappeared-in-an-array/find_all_numbers_disappeared_in_an_array_test.go
deleted file mode 100644
index 14d09516c..000000000
--- a/problems/find-all-numbers-disappeared-in-an-array/find_all_numbers_disappeared_in_an_array_test.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package problem448
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestFindDisappearedNumbers(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{4, 3, 2, 7, 8, 2, 3, 1},
-			want: []int{5, 6},
-		},
-		{
-			in:   []int{5, 4, 2, 3, 1},
-			want: []int{},
-		},
-		{
-			in:   []int{1, 1},
-			want: []int{2},
-		},
-	}
-	for _, tt := range tests {
-		got := findDisappearedNumbers(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/find-all-people-with-secret/README.md b/problems/find-all-people-with-secret/README.md
deleted file mode 100644
index 0ff67d5f5..000000000
--- a/problems/find-all-people-with-secret/README.md
+++ /dev/null
@@ -1,95 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../removing-minimum-and-maximum-from-array "Removing Minimum and Maximum From Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-reach-city-with-discounts "Minimum Cost to Reach City With Discounts")
-
-## [2092. Find All People With Secret (Hard)](https://leetcode.com/problems/find-all-people-with-secret "找出知晓秘密的所有专家")
-
-<p>You are given an integer <code>n</code> indicating there are <code>n</code> people numbered from <code>0</code> to <code>n - 1</code>. You are also given a <strong>0-indexed</strong> 2D integer array <code>meetings</code> where <code>meetings[i] = [x<sub>i</sub>, y<sub>i</sub>, time<sub>i</sub>]</code> indicates that person <code>x<sub>i</sub></code> and person <code>y<sub>i</sub></code> have a meeting at <code>time<sub>i</sub></code>. A person may attend <strong>multiple meetings</strong> at the same time. Finally, you are given an integer <code>firstPerson</code>.</p>
-
-<p>Person <code>0</code> has a <strong>secret</strong> and initially shares the secret with a person <code>firstPerson</code> at time <code>0</code>. This secret is then shared every time a meeting takes place with a person that has the secret. More formally, for every meeting, if a person <code>x<sub>i</sub></code> has the secret at <code>time<sub>i</sub></code>, then they will share the secret with person <code>y<sub>i</sub></code>, and vice versa.</p>
-
-<p>The secrets are shared <strong>instantaneously</strong>. That is, a person may receive the secret and share it with people in other meetings within the same time frame.</p>
-
-<p>Return <em>a list of all the people that have the secret after all the meetings have taken place. </em>You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6, meetings = [[1,2,5],[2,3,8],[1,5,10]], firstPerson = 1
-<strong>Output:</strong> [0,1,2,3,5]
-<strong>Explanation:
-</strong>At time 0, person 0 shares the secret with person 1.
-At time 5, person 1 shares the secret with person 2.
-At time 8, person 2 shares the secret with person 3.
-At time 10, person 1 shares the secret with person 5.​​​​
-Thus, people 0, 1, 2, 3, and 5 know the secret after all the meetings.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, meetings = [[3,1,3],[1,2,2],[0,3,3]], firstPerson = 3
-<strong>Output:</strong> [0,1,3]
-<strong>Explanation:</strong>
-At time 0, person 0 shares the secret with person 3.
-At time 2, neither person 1 nor person 2 know the secret.
-At time 3, person 3 shares the secret with person 0 and person 1.
-Thus, people 0, 1, and 3 know the secret after all the meetings.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, meetings = [[3,4,2],[1,2,1],[2,3,1]], firstPerson = 1
-<strong>Output:</strong> [0,1,2,3,4]
-<strong>Explanation:</strong>
-At time 0, person 0 shares the secret with person 1.
-At time 1, person 1 shares the secret with person 2, and person 2 shares the secret with person 3.
-Note that person 2 can share the secret at the same time as receiving it.
-At time 2, person 3 shares the secret with person 4.
-Thus, people 0, 1, 2, 3, and 4 know the secret after all the meetings.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= meetings.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>meetings[i].length == 3</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i </sub>&lt;= n - 1</code></li>
-	<li><code>x<sub>i</sub> != y<sub>i</sub></code></li>
-	<li><code>1 &lt;= time<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= firstPerson &lt;= n - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could you model all the meetings happening at the same time as a graph?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What data structure can you use to efficiently share the secret?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can use the union-find data structure to quickly determine who knows the secret and share the secret.
-</details>
diff --git a/problems/find-all-possible-recipes-from-given-supplies/README.md b/problems/find-all-possible-recipes-from-given-supplies/README.md
deleted file mode 100644
index a2dc609d4..000000000
--- a/problems/find-all-possible-recipes-from-given-supplies/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-words-found-in-sentences "Maximum Number of Words Found in Sentences")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-a-parentheses-string-can-be-valid "Check if a Parentheses String Can Be Valid")
-
-## [2115. Find All Possible Recipes from Given Supplies (Medium)](https://leetcode.com/problems/find-all-possible-recipes-from-given-supplies "从给定原材料中找到所有可以做出的菜")
-
-<p>You have information about <code>n</code> different recipes. You are given a string array <code>recipes</code> and a 2D string array <code>ingredients</code>. The <code>i<sup>th</sup></code> recipe has the name <code>recipes[i]</code>, and you can <strong>create</strong> it if you have <strong>all</strong> the needed ingredients from <code>ingredients[i]</code>. Ingredients to a recipe may need to be created from <strong>other </strong>recipes, i.e., <code>ingredients[i]</code> may contain a string that is in <code>recipes</code>.</p>
-
-<p>You are also given a string array <code>supplies</code> containing all the ingredients that you initially have, and you have an infinite supply of all of them.</p>
-
-<p>Return <em>a list of all the recipes that you can create. </em>You may return the answer in <strong>any order</strong>.</p>
-
-<p>Note that two recipes may contain each other in their ingredients.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> recipes = [&quot;bread&quot;], ingredients = [[&quot;yeast&quot;,&quot;flour&quot;]], supplies = [&quot;yeast&quot;,&quot;flour&quot;,&quot;corn&quot;]
-<strong>Output:</strong> [&quot;bread&quot;]
-<strong>Explanation:</strong>
-We can create &quot;bread&quot; since we have the ingredients &quot;yeast&quot; and &quot;flour&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> recipes = [&quot;bread&quot;,&quot;sandwich&quot;], ingredients = [[&quot;yeast&quot;,&quot;flour&quot;],[&quot;bread&quot;,&quot;meat&quot;]], supplies = [&quot;yeast&quot;,&quot;flour&quot;,&quot;meat&quot;]
-<strong>Output:</strong> [&quot;bread&quot;,&quot;sandwich&quot;]
-<strong>Explanation:</strong>
-We can create &quot;bread&quot; since we have the ingredients &quot;yeast&quot; and &quot;flour&quot;.
-We can create &quot;sandwich&quot; since we have the ingredient &quot;meat&quot; and can create the ingredient &quot;bread&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> recipes = [&quot;bread&quot;,&quot;sandwich&quot;,&quot;burger&quot;], ingredients = [[&quot;yeast&quot;,&quot;flour&quot;],[&quot;bread&quot;,&quot;meat&quot;],[&quot;sandwich&quot;,&quot;meat&quot;,&quot;bread&quot;]], supplies = [&quot;yeast&quot;,&quot;flour&quot;,&quot;meat&quot;]
-<strong>Output:</strong> [&quot;bread&quot;,&quot;sandwich&quot;,&quot;burger&quot;]
-<strong>Explanation:</strong>
-We can create &quot;bread&quot; since we have the ingredients &quot;yeast&quot; and &quot;flour&quot;.
-We can create &quot;sandwich&quot; since we have the ingredient &quot;meat&quot; and can create the ingredient &quot;bread&quot;.
-We can create &quot;burger&quot; since we have the ingredient &quot;meat&quot; and can create the ingredients &quot;bread&quot; and &quot;sandwich&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == recipes.length == ingredients.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= ingredients[i].length, supplies.length &lt;= 100</code></li>
-	<li><code>1 &lt;= recipes[i].length, ingredients[i][j].length, supplies[k].length &lt;= 10</code></li>
-	<li><code>recipes[i], ingredients[i][j]</code>, and <code>supplies[k]</code> consist only of lowercase English letters.</li>
-	<li>All the values of <code>recipes</code> and <code>supplies</code>&nbsp;combined are unique.</li>
-	<li>Each <code>ingredients[i]</code> does not contain any duplicate values.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we use a data structure to quickly query whether we have a certain ingredient?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Once we verify that we can make a recipe, we can add it to our ingredient data structure. We can then check if we can make more recipes as a result of this.
-</details>
diff --git a/problems/find-all-the-lonely-nodes/README.md b/problems/find-all-the-lonely-nodes/README.md
deleted file mode 100644
index d7b5cec33..000000000
--- a/problems/find-all-the-lonely-nodes/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../calculate-salaries "Calculate Salaries")
-　　　　　　　　　　　　　　　　
-[Next >](../shuffle-the-array "Shuffle the Array")
-
-## [1469. Find All The Lonely Nodes (Easy)](https://leetcode.com/problems/find-all-the-lonely-nodes "寻找所有的独生节点")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Tilt](../binary-tree-tilt) (Easy)
-  1. [Univalued Binary Tree](../univalued-binary-tree) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do a simple tree traversal, try to check if the current node is lonely or not.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Node is lonely if at least one of the left/right pointers is null.
-</details>
diff --git a/problems/find-anagram-mappings/README.md b/problems/find-anagram-mappings/README.md
deleted file mode 100644
index b6077c62e..000000000
--- a/problems/find-anagram-mappings/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../employee-free-time "Employee Free Time")
-　　　　　　　　　　　　　　　　
-[Next >](../special-binary-string "Special Binary String")
-
-## [760. Find Anagram Mappings (Easy)](https://leetcode.com/problems/find-anagram-mappings "找出变位映射")
-
-<p>
-Given two lists <code>A</code>and <code>B</code>, and <code>B</code> is an anagram of <code>A</code>. <code>B</code> is an anagram of <code>A</code> means <code>B</code> is made by randomizing the order of the elements in <code>A</code>.
-</p><p>
-We want to find an <i>index mapping</i> <code>P</code>, from <code>A</code> to <code>B</code>. A mapping <code>P[i] = j</code> means the <code>i</code>th element in <code>A</code> appears in <code>B</code> at index <code>j</code>.
-</p><p>
-These lists <code>A</code> and <code>B</code> may contain duplicates.  If there are multiple answers, output any of them.
-</p>
-
-<p>
-For example, given
-<pre>
-A = [12, 28, 46, 32, 50]
-B = [50, 12, 32, 46, 28]
-</pre>
-</p>
-We should return
-<pre>
-[1, 4, 3, 2, 0]
-</pre>
-as <code>P[0] = 1</code> because the <code>0</code>th element of <code>A</code> appears at <code>B[1]</code>,
-and <code>P[1] = 4</code> because the <code>1</code>st element of <code>A</code> appears at <code>B[4]</code>,
-and so on.
-</p>
-
-<p><b>Note:</b><ol>
-<li><code>A, B</code> have equal lengths in range <code>[1, 100]</code>.</li>
-<li><code>A[i], B[i]</code> are integers in range <code>[0, 10^5]</code>.</li>
-</ol></p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create a hashmap so that D[x] = i  whenever B[i] = x.  Then, the answer is [D[x] for x in A].
-</details>
diff --git a/problems/find-anagram-mappings/find_anagram_mappings.go b/problems/find-anagram-mappings/find_anagram_mappings.go
deleted file mode 100644
index f7889cb75..000000000
--- a/problems/find-anagram-mappings/find_anagram_mappings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem760
diff --git a/problems/find-anagram-mappings/find_anagram_mappings_test.go b/problems/find-anagram-mappings/find_anagram_mappings_test.go
deleted file mode 100644
index f7889cb75..000000000
--- a/problems/find-anagram-mappings/find_anagram_mappings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem760
diff --git a/problems/find-and-replace-in-string/README.md b/problems/find-and-replace-in-string/README.md
deleted file mode 100644
index 1d762c099..000000000
--- a/problems/find-and-replace-in-string/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flipping-an-image "Flipping an Image")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-distances-in-tree "Sum of Distances in Tree")
-
-## [833. Find And Replace in String (Medium)](https://leetcode.com/problems/find-and-replace-in-string "字符串中的查找与替换")
-
-<p>You are given a <strong>0-indexed</strong> string <code>s</code> that you must perform <code>k</code> replacement operations on. The replacement operations are given as three <strong>0-indexed</strong> parallel arrays, <code>indices</code>, <code>sources</code>, and <code>targets</code>, all of length <code>k</code>.</p>
-
-<p>To complete the <code>i<sup>th</sup></code> replacement operation:</p>
-
-<ol>
-	<li>Check if the <strong>substring</strong> <code>sources[i]</code> occurs at index <code>indices[i]</code> in the <strong>original string</strong> <code>s</code>.</li>
-	<li>If it does not occur, <strong>do nothing</strong>.</li>
-	<li>Otherwise if it does occur, <strong>replace</strong> that substring with <code>targets[i]</code>.</li>
-</ol>
-
-<p>For example, if <code>s = &quot;<u>ab</u>cd&quot;</code>, <code>indices[i] = 0</code>, <code>sources[i] = &quot;ab&quot;</code>, and <code>targets[i] = &quot;eee&quot;</code>, then the result of this replacement will be <code>&quot;<u>eee</u>cd&quot;</code>.</p>
-
-<p>All replacement operations must occur <strong>simultaneously</strong>, meaning the replacement operations should not affect the indexing of each other. The testcases will be generated such that the replacements will <strong>not overlap</strong>.</p>
-
-<ul>
-	<li>For example, a testcase with <code>s = &quot;abc&quot;</code>, <code>indices = [0, 1]</code>, and <code>sources = [&quot;ab&quot;,&quot;bc&quot;]</code> will not be generated because the <code>&quot;ab&quot;</code> and <code>&quot;bc&quot;</code> replacements overlap.</li>
-</ul>
-
-<p>Return <em>the <strong>resulting string</strong> after performing all replacement operations on </em><code>s</code>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters in a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/12/833-ex1.png" style="width: 411px; height: 251px;" />
-<pre>
-<strong>Input:</strong> s = &quot;abcd&quot;, indices = [0, 2], sources = [&quot;a&quot;, &quot;cd&quot;], targets = [&quot;eee&quot;, &quot;ffff&quot;]
-<strong>Output:</strong> &quot;eeebffff&quot;
-<strong>Explanation:</strong>
-&quot;a&quot; occurs at index 0 in s, so we replace it with &quot;eee&quot;.
-&quot;cd&quot; occurs at index 2 in s, so we replace it with &quot;ffff&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/12/833-ex2-1.png" style="width: 411px; height: 251px;" />
-<pre>
-<strong>Input:</strong> s = &quot;abcd&quot;, indices = [0, 2], sources = [&quot;ab&quot;,&quot;ec&quot;], targets = [&quot;eee&quot;,&quot;ffff&quot;]
-<strong>Output:</strong> &quot;eeecd&quot;
-<strong>Explanation:</strong>
-&quot;ab&quot; occurs at index 0 in s, so we replace it with &quot;eee&quot;.
-&quot;ec&quot; does not occur at index 2 in s, so we do nothing.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>k == indices.length == sources.length == targets.length</code></li>
-	<li><code>1 &lt;= k &lt;= 100</code></li>
-	<li><code>0 &lt;= indexes[i] &lt; s.length</code></li>
-	<li><code>1 &lt;= sources[i].length, targets[i].length &lt;= 50</code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-	<li><code>sources[i]</code> and <code>targets[i]</code> consist of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/find-and-replace-in-string/find_and_replace_in_string.go b/problems/find-and-replace-in-string/find_and_replace_in_string.go
deleted file mode 100644
index c1e11a593..000000000
--- a/problems/find-and-replace-in-string/find_and_replace_in_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem833
diff --git a/problems/find-and-replace-in-string/find_and_replace_in_string_test.go b/problems/find-and-replace-in-string/find_and_replace_in_string_test.go
deleted file mode 100644
index c1e11a593..000000000
--- a/problems/find-and-replace-in-string/find_and_replace_in_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem833
diff --git a/problems/find-and-replace-pattern/README.md b/problems/find-and-replace-pattern/README.md
deleted file mode 100644
index 9dfda5196..000000000
--- a/problems/find-and-replace-pattern/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-binary-tree-from-preorder-and-postorder-traversal "Construct Binary Tree from Preorder and Postorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-subsequence-widths "Sum of Subsequence Widths")
-
-## [890. Find and Replace Pattern (Medium)](https://leetcode.com/problems/find-and-replace-pattern "查找和替换模式")
-
-<p>Given a list of strings <code>words</code> and a string <code>pattern</code>, return <em>a list of</em> <code>words[i]</code> <em>that match</em> <code>pattern</code>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>A word matches the pattern if there exists a permutation of letters <code>p</code> so that after replacing every letter <code>x</code> in the pattern with <code>p(x)</code>, we get the desired word.</p>
-
-<p>Recall that a permutation of letters is a bijection from letters to letters: every letter maps to another letter, and no two letters map to the same letter.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;abc&quot;,&quot;deq&quot;,&quot;mee&quot;,&quot;aqq&quot;,&quot;dkd&quot;,&quot;ccc&quot;], pattern = &quot;abb&quot;
-<strong>Output:</strong> [&quot;mee&quot;,&quot;aqq&quot;]
-<strong>Explanation:</strong> &quot;mee&quot; matches the pattern because there is a permutation {a -&gt; m, b -&gt; e, ...}. 
-&quot;ccc&quot; does not match the pattern because {a -&gt; c, b -&gt; c, ...} is not a permutation, since a and b map to the same letter.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;a&quot;,&quot;b&quot;,&quot;c&quot;], pattern = &quot;a&quot;
-<strong>Output:</strong> [&quot;a&quot;,&quot;b&quot;,&quot;c&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= pattern.length &lt;= 20</code></li>
-	<li><code>1 &lt;= words.length &lt;= 50</code></li>
-	<li><code>words[i].length == pattern.length</code></li>
-	<li><code>pattern</code> and <code>words[i]</code> are lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/find-and-replace-pattern/find_and_replace_pattern.go b/problems/find-and-replace-pattern/find_and_replace_pattern.go
deleted file mode 100644
index df944bcaf..000000000
--- a/problems/find-and-replace-pattern/find_and_replace_pattern.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem890
diff --git a/problems/find-and-replace-pattern/find_and_replace_pattern_test.go b/problems/find-and-replace-pattern/find_and_replace_pattern_test.go
deleted file mode 100644
index df944bcaf..000000000
--- a/problems/find-and-replace-pattern/find_and_replace_pattern_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem890
diff --git a/problems/find-array-given-subset-sums/README.md b/problems/find-array-given-subset-sums/README.md
deleted file mode 100644
index 70ed5cc1f..000000000
--- a/problems/find-array-given-subset-sums/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimize-the-difference-between-target-and-chosen-elements "Minimize the Difference Between Target and Chosen Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../widest-pair-of-indices-with-equal-range-sum "Widest Pair of Indices With Equal Range Sum")
-
-## [1982. Find Array Given Subset Sums (Hard)](https://leetcode.com/problems/find-array-given-subset-sums "从子集的和还原数组")
-
-<p>You are given an integer <code>n</code> representing the length of an unknown array that you are trying to recover. You are also given an array <code>sums</code> containing the values of all <code>2<sup>n</sup></code> <strong>subset sums</strong> of the unknown array (in no particular order).</p>
-
-<p>Return <em>the array </em><code>ans</code><em> of length </em><code>n</code><em> representing the unknown array. If <strong>multiple</strong> answers exist, return <strong>any</strong> of them</em>.</p>
-
-<p>An array <code>sub</code> is a <strong>subset</strong> of an array <code>arr</code> if <code>sub</code> can be obtained from <code>arr</code> by deleting some (possibly zero or all) elements of <code>arr</code>. The sum of the elements in <code>sub</code> is one possible <strong>subset sum</strong> of <code>arr</code>. The sum of an empty array is considered to be <code>0</code>.</p>
-
-<p><strong>Note:</strong> Test cases are generated such that there will <strong>always</strong> be at least one correct answer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, sums = [-3,-2,-1,0,0,1,2,3]
-<strong>Output:</strong> [1,2,-3]
-<strong>Explanation: </strong>[1,2,-3] is able to achieve the given subset sums:
-- []: sum is 0
-- [1]: sum is 1
-- [2]: sum is 2
-- [1,2]: sum is 3
-- [-3]: sum is -3
-- [1,-3]: sum is -2
-- [2,-3]: sum is -1
-- [1,2,-3]: sum is 0
-Note that any permutation of [1,2,-3] and also any permutation of [-1,-2,3] will also be accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, sums = [0,0,0,0]
-<strong>Output:</strong> [0,0]
-<strong>Explanation:</strong> The only correct answer is [0,0].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, sums = [0,0,5,5,4,-1,4,9,9,-1,4,3,4,8,3,8]
-<strong>Output:</strong> [0,-1,4,5]
-<strong>Explanation:</strong> [0,-1,4,5] is able to achieve the given subset sums.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 15</code></li>
-	<li><code>sums.length == 2<sup>n</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= sums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What information do the two largest elements tell us?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use recursion to check all possible states?
-</details>
diff --git a/problems/find-bottom-left-tree-value/README.md b/problems/find-bottom-left-tree-value/README.md
deleted file mode 100644
index 0bddae477..000000000
--- a/problems/find-bottom-left-tree-value/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../game-play-analysis-ii "Game Play Analysis II")
-　　　　　　　　　　　　　　　　
-[Next >](../freedom-trail "Freedom Trail")
-
-## [513. Find Bottom Left Tree Value (Medium)](https://leetcode.com/problems/find-bottom-left-tree-value "找树左下角的值")
-
-<p>Given the <code>root</code> of a binary tree, return the leftmost value in the last row of the tree.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/14/tree1.jpg" style="width: 302px; height: 182px;" />
-<pre>
-<strong>Input:</strong> root = [2,1,3]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/14/tree2.jpg" style="width: 432px; height: 421px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,null,5,6,null,null,7]
-<strong>Output:</strong> 7
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-2<sup>31</sup> &lt;= Node.val &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/find-bottom-left-tree-value/find_bottom_left_tree_value.go b/problems/find-bottom-left-tree-value/find_bottom_left_tree_value.go
deleted file mode 100644
index 1052b9c03..000000000
--- a/problems/find-bottom-left-tree-value/find_bottom_left_tree_value.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem513
diff --git a/problems/find-bottom-left-tree-value/find_bottom_left_tree_value_test.go b/problems/find-bottom-left-tree-value/find_bottom_left_tree_value_test.go
deleted file mode 100644
index 1052b9c03..000000000
--- a/problems/find-bottom-left-tree-value/find_bottom_left_tree_value_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem513
diff --git a/problems/find-center-of-star-graph/README.md b/problems/find-center-of-star-graph/README.md
deleted file mode 100644
index 62c53fe1e..000000000
--- a/problems/find-center-of-star-graph/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-one-string-swap-can-make-strings-equal "Check if One String Swap Can Make Strings Equal")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-average-pass-ratio "Maximum Average Pass Ratio")
-
-## [1791. Find Center of Star Graph (Easy)](https://leetcode.com/problems/find-center-of-star-graph "找出星型图的中心节点")
-
-<p>There is an undirected <strong>star</strong> graph consisting of <code>n</code> nodes labeled from <code>1</code> to <code>n</code>. A star graph is a graph where there is one <strong>center</strong> node and <strong>exactly</strong> <code>n - 1</code> edges that connect the center node with every other node.</p>
-
-<p>You are given a 2D integer array <code>edges</code> where each <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> indicates that there is an edge between the nodes <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code>. Return the center of the given star graph.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/24/star_graph.png" style="width: 331px; height: 321px;" />
-<pre>
-<strong>Input:</strong> edges = [[1,2],[2,3],[4,2]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> As shown in the figure above, node 2 is connected to every other node, so 2 is the center.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> edges = [[1,2],[5,1],[1,3],[1,4]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>edges.length == n - 1</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>1 &lt;= u<sub>i,</sub> v<sub>i</sub> &lt;= n</code></li>
-	<li><code>u<sub>i</sub> != v<sub>i</sub></code></li>
-	<li>The given <code>edges</code> represent a valid star graph.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The center is the only node that has more than one edge.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The center is also connected to all other nodes.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Any two edges must have a common node, which is the center.
-</details>
diff --git a/problems/find-common-characters/README.md b/problems/find-common-characters/README.md
deleted file mode 100644
index 67afcca85..000000000
--- a/problems/find-common-characters/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../grid-illumination "Grid Illumination")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-word-is-valid-after-substitutions "Check If Word Is Valid After Substitutions")
-
-## [1002. Find Common Characters (Easy)](https://leetcode.com/problems/find-common-characters "查找常用字符")
-
-<p>Given a string array <code>words</code>, return <em>an array of all characters that show up in all strings within the </em><code>words</code><em> (including duplicates)</em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> words = ["bella","label","roller"]
-<strong>Output:</strong> ["e","l","l"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> words = ["cool","lock","cook"]
-<strong>Output:</strong> ["c","o"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 100</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 100</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Intersection of Two Arrays II](../intersection-of-two-arrays-ii) (Easy)
diff --git a/problems/find-common-characters/find_common_characters.go b/problems/find-common-characters/find_common_characters.go
deleted file mode 100644
index 468ed7a6d..000000000
--- a/problems/find-common-characters/find_common_characters.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem1002
-
-import "fmt"
-
-func commonChars(A []string) []string {
-	ans, m, l := make([]string, 0), make([][26]int, len(A)), len(A)
-	for i, str := range A {
-		for _, c := range str {
-			m[i][c-'a']++
-		}
-	}
-	for i, c := range m[0] {
-		for c > 0 {
-			c--
-			for j := 1; j < l; j++ {
-				if m[j][i] > 0 {
-					m[j][i]--
-				} else {
-					c = -1
-					break
-				}
-			}
-			if c >= 0 {
-				ans = append(ans, fmt.Sprintf("%c", i+'a'))
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/find-common-characters/find_common_characters_test.go b/problems/find-common-characters/find_common_characters_test.go
deleted file mode 100644
index 09ce43df3..000000000
--- a/problems/find-common-characters/find_common_characters_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem1002
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []string
-	want []string
-}
-
-func TestCommonChars(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []string{"bella", "label", "roller"},
-			want: []string{"e", "l", "l"},
-		},
-		{
-			in:   []string{"cool", "lock", "cook"},
-			want: []string{"c", "o"},
-		},
-	}
-	for _, tt := range tests {
-		got := commonChars(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree/README.md b/problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree/README.md
deleted file mode 100644
index 01117621a..000000000
--- a/problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../avoid-flood-in-the-city "Avoid Flood in The City")
-　　　　　　　　　　　　　　　　
-[Next >](../clone-n-ary-tree "Clone N-ary Tree")
-
-## [1489. Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree (Hard)](https://leetcode.com/problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree "找到最小生成树里的关键边和伪关键边")
-
-<p>Given a weighted undirected connected graph with <code>n</code>&nbsp;vertices numbered from <code>0</code> to <code>n - 1</code>,&nbsp;and an array <code>edges</code>&nbsp;where <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>, weight<sub>i</sub>]</code> represents a bidirectional and weighted edge between nodes&nbsp;<code>a<sub>i</sub></code>&nbsp;and <code>b<sub>i</sub></code>. A minimum spanning tree (MST) is a subset of the graph&#39;s edges that connects all vertices without cycles&nbsp;and with the minimum possible total edge weight.</p>
-
-<p>Find <em>all the critical and pseudo-critical edges in the given graph&#39;s minimum spanning tree (MST)</em>. An MST edge whose deletion from the graph would cause the MST weight to increase is called a&nbsp;<em>critical edge</em>. On&nbsp;the other hand, a pseudo-critical edge is that which can appear in some MSTs but not all.</p>
-
-<p>Note that you can return the indices of the edges in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/06/04/ex1.png" style="width: 259px; height: 262px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 5, edges = [[0,1,1],[1,2,1],[2,3,2],[0,3,2],[0,4,3],[3,4,3],[1,4,6]]
-<strong>Output:</strong> [[0,1],[2,3,4,5]]
-<strong>Explanation:</strong> The figure above describes the graph.
-The following figure shows all the possible MSTs:
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/04/msts.png" style="width: 540px; height: 553px;" />
-Notice that the two edges 0 and 1 appear in all MSTs, therefore they are critical edges, so we return them in the first list of the output.
-The edges 2, 3, 4, and 5 are only part of some MSTs, therefore they are considered pseudo-critical edges. We add them to the second list of the output.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/06/04/ex2.png" style="width: 247px; height: 253px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 4, edges = [[0,1,1],[1,2,1],[2,3,1],[0,3,1]]
-<strong>Output:</strong> [[],[0,1,2,3]]
-<strong>Explanation:</strong> We can observe that since all 4 edges have equal weight, choosing any 3 edges from the given 4 will yield an MST. Therefore all 4 edges are pseudo-critical.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= edges.length &lt;= min(200, n * (n - 1) / 2)</code></li>
-	<li><code>edges[i].length == 3</code></li>
-	<li><code>0 &lt;= a<sub>i</sub> &lt; b<sub>i</sub> &lt; n</code></li>
-	<li><code>1 &lt;= weight<sub>i</sub>&nbsp;&lt;= 1000</code></li>
-	<li>All pairs <code>(a<sub>i</sub>, b<sub>i</sub>)</code> are <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Minimum Spanning Tree](../../tag/minimum-spanning-tree/README.md)]
-  [[Strongly Connected Component](../../tag/strongly-connected-component/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use the Kruskal algorithm to find the minimum spanning tree by sorting the edges and picking edges from ones with smaller weights.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a disjoint set to avoid adding redundant edges that result in a cycle.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-To find if one edge is critical, delete that edge and re-run the MST algorithm and see if the weight of the new MST increases.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-To find if one edge is non-critical (in any MST), include that edge to the accepted edge list and continue the MST algorithm, then see if the resulting MST has the same weight of the initial MST of the entire graph.
-</details>
diff --git a/problems/find-cumulative-salary-of-an-employee/README.md b/problems/find-cumulative-salary-of-an-employee/README.md
deleted file mode 100644
index 58c172bf3..000000000
--- a/problems/find-cumulative-salary-of-an-employee/README.md
+++ /dev/null
@@ -1,101 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../get-highest-answer-rate-question "Get Highest Answer Rate Question")
-　　　　　　　　　　　　　　　　
-[Next >](../count-student-number-in-departments "Count Student Number in Departments")
-
-## [579. Find Cumulative Salary of an Employee (Hard)](https://leetcode.com/problems/find-cumulative-salary-of-an-employee "查询员工的累计薪水")
-
-<p>The <b>Employee</b> table holds the salary information in a year.</p>
-
-<p>Write a SQL to get the cumulative sum of an employee&#39;s salary over a period of 3 months but exclude the most recent month.</p>
-
-<p>The result should be displayed by &#39;Id&#39; ascending, and then by &#39;Month&#39; descending.</p>
-
-<p><b>Example</b><br />
-<b>Input</b></p>
-
-<pre>
-| Id | Month | Salary |
-|----|-------|--------|
-| 1  | 1     | 20     |
-| 2  | 1     | 20     |
-| 1  | 2     | 30     |
-| 2  | 2     | 30     |
-| 3  | 2     | 40     |
-| 1  | 3     | 40     |
-| 3  | 3     | 60     |
-| 1  | 4     | 60     |
-| 3  | 4     | 70     |
-</pre>
-<b>Output</b>
-
-<pre>
-
-| Id | Month | Salary |
-|----|-------|--------|
-| 1  | 3     | 90     |
-| 1  | 2     | 50     |
-| 1  | 1     | 20     |
-| 2  | 1     | 20     |
-| 3  | 3     | 100    |
-| 3  | 2     | 40     |
-</pre>
-
-<p>&nbsp;</p>
-<b>Explanation</b>
-
-<p>Employee &#39;1&#39; has 3 salary records for the following 3 months except the most recent month &#39;4&#39;: salary 40 for month &#39;3&#39;, 30 for month &#39;2&#39; and 20 for month &#39;1&#39;<br />
-So the cumulative sum of salary of this employee over 3 months is 90(40+30+20), 50(30+20) and 20 respectively.</p>
-
-<pre>
-| Id | Month | Salary |
-|----|-------|--------|
-| 1  | 3     | 90     |
-| 1  | 2     | 50     |
-| 1  | 1     | 20     |
-</pre>
-Employee &#39;2&#39; only has one salary record (month &#39;1&#39;) except its most recent month &#39;2&#39;.
-
-<pre>
-| Id | Month | Salary |
-|----|-------|--------|
-| 2  | 1     | 20     |
-</pre>
-
-<p>&nbsp;</p>
-Employ &#39;3&#39; has two salary records except its most recent pay month &#39;4&#39;: month &#39;3&#39; with 60 and month &#39;2&#39; with 40. So the cumulative salary is as following.
-
-<pre>
-| Id | Month | Salary |
-|----|-------|--------|
-| 3  | 3     | 100    |
-| 3  | 2     | 40     |
-</pre>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Seem hard at first glance? Try to divide this problem into some sub-problems. 
-Think about how to calculate the cumulative sum of one employee, how to get the cumulative sum for many employees, and how to except the most recent month of the result.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the technique of self-join if you have only one table but to write a complex query.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Still remember how to use the function `sum` and `max`?
-</details>
diff --git a/problems/find-cumulative-salary-of-an-employee/find_cumulative_salary_of_an_employee.sql b/problems/find-cumulative-salary-of-an-employee/find_cumulative_salary_of_an_employee.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/find-cumulative-salary-of-an-employee/find_cumulative_salary_of_an_employee.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/find-cumulative-salary-of-an-employee/mysql_schemas.sql b/problems/find-cumulative-salary-of-an-employee/mysql_schemas.sql
deleted file mode 100644
index c5a0ea410..000000000
--- a/problems/find-cumulative-salary-of-an-employee/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Employee (Id int, Month int, Salary int);
-Truncate table Employee;
-insert into Employee (Id, Month, Salary) values ('1', '1', '20');
-insert into Employee (Id, Month, Salary) values ('2', '1', '20');
-insert into Employee (Id, Month, Salary) values ('1', '2', '30');
-insert into Employee (Id, Month, Salary) values ('2', '2', '30');
-insert into Employee (Id, Month, Salary) values ('3', '2', '40');
-insert into Employee (Id, Month, Salary) values ('1', '3', '40');
-insert into Employee (Id, Month, Salary) values ('3', '3', '60');
-insert into Employee (Id, Month, Salary) values ('1', '4', '60');
-insert into Employee (Id, Month, Salary) values ('3', '4', '70');
-insert into Employee (Id, Month, Salary) values ('1', '7', '90');
-insert into Employee (Id, Month, Salary) values ('1', '8', '90');
diff --git a/problems/find-customer-referee/README.md b/problems/find-customer-referee/README.md
deleted file mode 100644
index 1a32fee64..000000000
--- a/problems/find-customer-referee/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-operation-for-two-strings "Delete Operation for Two Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../investments-in-2016 "Investments in 2016")
-
-## [584. Find Customer Referee (Easy)](https://leetcode.com/problems/find-customer-referee "寻找用户推荐人")
-
-<p>Given a table <code>customer</code> holding customers information and the referee.</p>
-
-<pre>
-+------+------+-----------+
-| id   | name | referee_id|
-+------+------+-----------+
-|    1 | Will |      NULL |
-|    2 | Jane |      NULL |
-|    3 | Alex |         2 |
-|    4 | Bill |      NULL |
-|    5 | Zack |         1 |
-|    6 | Mark |         2 |
-+------+------+-----------+
-</pre>
-
-<p>Write a query to return the list of customers <b>NOT</b> referred by the person with id &#39;2&#39;.</p>
-
-<p>For the sample data above, the result is:</p>
-
-<pre>
-+------+
-| name |
-+------+
-| Will |
-| Jane |
-| Bill |
-| Zack |
-+------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Be careful of the NULL value
-</details>
diff --git a/problems/find-customer-referee/find_customer_referee.sql b/problems/find-customer-referee/find_customer_referee.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/find-customer-referee/find_customer_referee.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/find-customer-referee/mysql_schemas.sql b/problems/find-customer-referee/mysql_schemas.sql
deleted file mode 100644
index 77f4671ec..000000000
--- a/problems/find-customer-referee/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Customer (id int, name varchar(25), referee_id int);
-Truncate table Customer;
-insert into Customer (id, name, referee_id) values ('1', 'Will', 'None');
-insert into Customer (id, name, referee_id) values ('2', 'Jane', 'None');
-insert into Customer (id, name, referee_id) values ('3', 'Alex', '2');
-insert into Customer (id, name, referee_id) values ('4', 'Bill', 'None');
-insert into Customer (id, name, referee_id) values ('5', 'Zack', '1');
-insert into Customer (id, name, referee_id) values ('6', 'Mark', '2');
diff --git a/problems/find-customers-with-positive-revenue-this-year/README.md b/problems/find-customers-with-positive-revenue-this-year/README.md
deleted file mode 100644
index aff999682..000000000
--- a/problems/find-customers-with-positive-revenue-this-year/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-accepted-invitations "Maximum Number of Accepted Invitations")
-　　　　　　　　　　　　　　　　
-[Next >](../sign-of-the-product-of-an-array "Sign of the Product of an Array")
-
-## [1821. Find Customers With Positive Revenue this Year (Easy)](https://leetcode.com/problems/find-customers-with-positive-revenue-this-year "寻找今年具有正收入的客户")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/find-customers-with-positive-revenue-this-year/mysql_schemas.sql b/problems/find-customers-with-positive-revenue-this-year/mysql_schemas.sql
deleted file mode 100644
index 3f9c8999d..000000000
--- a/problems/find-customers-with-positive-revenue-this-year/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Customers (customer_id int, year int, revenue int);
-Truncate table Customers;
-insert into Customers (customer_id, year, revenue) values ('1', '2018', '50');
-insert into Customers (customer_id, year, revenue) values ('1', '2021', '30');
-insert into Customers (customer_id, year, revenue) values ('1', '2020', '70');
-insert into Customers (customer_id, year, revenue) values ('2', '2021', '-50');
-insert into Customers (customer_id, year, revenue) values ('3', '2018', '10');
-insert into Customers (customer_id, year, revenue) values ('3', '2016', '50');
-insert into Customers (customer_id, year, revenue) values ('4', '2021', '20');
diff --git a/problems/find-cutoff-score-for-each-school/README.md b/problems/find-cutoff-score-for-each-school/README.md
deleted file mode 100644
index 81a12ad5a..000000000
--- a/problems/find-cutoff-score-for-each-school/README.md
+++ /dev/null
@@ -1,14 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-unique-good-subsequences "Number of Unique Good Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-people-that-can-be-caught-in-tag "Maximum Number of People That Can Be Caught in Tag")
-
-## [1988. Find Cutoff Score for Each School (Medium)](https://leetcode.com/problems/find-cutoff-score-for-each-school "找出每所学校的最低分数要求")
-
-
diff --git a/problems/find-cutoff-score-for-each-school/mysql_schemas.sql b/problems/find-cutoff-score-for-each-school/mysql_schemas.sql
deleted file mode 100644
index 451883127..000000000
--- a/problems/find-cutoff-score-for-each-school/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Schools (school_id int, capacity int);
-Create table If Not Exists Exam (score int, student_count int);
-Truncate table Schools;
-insert into Schools (school_id, capacity) values ('11', '151');
-insert into Schools (school_id, capacity) values ('5', '48');
-insert into Schools (school_id, capacity) values ('9', '9');
-insert into Schools (school_id, capacity) values ('10', '99');
-Truncate table Exam;
-insert into Exam (score, student_count) values ('975', '10');
-insert into Exam (score, student_count) values ('966', '60');
-insert into Exam (score, student_count) values ('844', '76');
-insert into Exam (score, student_count) values ('749', '76');
-insert into Exam (score, student_count) values ('744', '100');
diff --git a/problems/find-distance-in-a-binary-tree/README.md b/problems/find-distance-in-a-binary-tree/README.md
deleted file mode 100644
index 3daa4c20d..000000000
--- a/problems/find-distance-in-a-binary-tree/README.md
+++ /dev/null
@@ -1,32 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../building-boxes "Building Boxes")
-　　　　　　　　　　　　　　　　
-[Next >](../find-total-time-spent-by-each-employee "Find Total Time Spent by Each Employee")
-
-## [1740. Find Distance in a Binary Tree (Medium)](https://leetcode.com/problems/find-distance-in-a-binary-tree "找到二叉树中的距离")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Get the LCA of p and q.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The answer is the sum of distances between p-LCA and q-LCA
-</details>
diff --git a/problems/find-duplicate-file-in-system/README.md b/problems/find-duplicate-file-in-system/README.md
deleted file mode 100644
index 2fddd47a6..000000000
--- a/problems/find-duplicate-file-in-system/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tree-node "Tree Node")
-　　　　　　　　　　　　　　　　
-[Next >](../triangle-judgement "Triangle Judgement")
-
-## [609. Find Duplicate File in System (Medium)](https://leetcode.com/problems/find-duplicate-file-in-system "在系统中查找重复文件")
-
-<p>Given a list <code>paths</code> of directory info, including the directory path, and all the files with contents in this directory, return <em>all the duplicate files in the file system in terms of their paths</em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>A group of duplicate files consists of at least two files that have the same content.</p>
-
-<p>A single directory info string in the input list has the following format:</p>
-
-<ul>
-	<li><code>&quot;root/d1/d2/.../dm f1.txt(f1_content) f2.txt(f2_content) ... fn.txt(fn_content)&quot;</code></li>
-</ul>
-
-<p>It means there are <code>n</code> files <code>(f1.txt, f2.txt ... fn.txt)</code> with content <code>(f1_content, f2_content ... fn_content)</code> respectively in the directory &quot;<code>root/d1/d2/.../dm&quot;</code>. Note that <code>n &gt;= 1</code> and <code>m &gt;= 0</code>. If <code>m = 0</code>, it means the directory is just the root directory.</p>
-
-<p>The output is a list of groups of duplicate file paths. For each group, it contains all the file paths of the files that have the same content. A file path is a string that has the following format:</p>
-
-<ul>
-	<li><code>&quot;directory_path/file_name.txt&quot;</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> paths = ["root/a 1.txt(abcd) 2.txt(efgh)","root/c 3.txt(abcd)","root/c/d 4.txt(efgh)","root 4.txt(efgh)"]
-<strong>Output:</strong> [["root/a/2.txt","root/c/d/4.txt","root/4.txt"],["root/a/1.txt","root/c/3.txt"]]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> paths = ["root/a 1.txt(abcd) 2.txt(efgh)","root/c 3.txt(abcd)","root/c/d 4.txt(efgh)"]
-<strong>Output:</strong> [["root/a/2.txt","root/c/d/4.txt"],["root/a/1.txt","root/c/3.txt"]]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= paths.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= paths[i].length &lt;= 3000</code></li>
-	<li><code>1 &lt;= sum(paths[i].length) &lt;= 5 * 10<sup>5</sup></code></li>
-	<li><code>paths[i]</code> consist of English letters, digits, <code>&#39;/&#39;</code>, <code>&#39;.&#39;</code>, <code>&#39;(&#39;</code>, <code>&#39;)&#39;</code>, and <code>&#39; &#39;</code>.</li>
-	<li>You may assume no files or directories share the same name in the same directory.</li>
-	<li>You may assume each given directory info represents a unique directory. A single blank space separates the directory path and file info.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>Imagine you are given a real file system, how will you search files? DFS or BFS?</li>
-	<li>If the file content is very large (GB level), how will you modify your solution?</li>
-	<li>If you can only read the file by 1kb each time, how will you modify your solution?</li>
-	<li>What is the time complexity of your modified solution? What is the most time-consuming part and memory-consuming part of it? How to optimize?</li>
-	<li>How to make sure the duplicated files you find are not false positive?</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Delete Duplicate Folders in System](../delete-duplicate-folders-in-system) (Hard)
diff --git a/problems/find-duplicate-file-in-system/find_duplicate_file_in_system.go b/problems/find-duplicate-file-in-system/find_duplicate_file_in_system.go
deleted file mode 100644
index 9d163b094..000000000
--- a/problems/find-duplicate-file-in-system/find_duplicate_file_in_system.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem609
diff --git a/problems/find-duplicate-file-in-system/find_duplicate_file_in_system_test.go b/problems/find-duplicate-file-in-system/find_duplicate_file_in_system_test.go
deleted file mode 100644
index 9d163b094..000000000
--- a/problems/find-duplicate-file-in-system/find_duplicate_file_in_system_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem609
diff --git a/problems/find-duplicate-subtrees/README.md b/problems/find-duplicate-subtrees/README.md
deleted file mode 100644
index 83c94b5a6..000000000
--- a/problems/find-duplicate-subtrees/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../4-keys-keyboard "4 Keys Keyboard")
-　　　　　　　　　　　　　　　　
-[Next >](../two-sum-iv-input-is-a-bst "Two Sum IV - Input is a BST")
-
-## [652. Find Duplicate Subtrees (Medium)](https://leetcode.com/problems/find-duplicate-subtrees "寻找重复的子树")
-
-<p>Given the <code>root</code>&nbsp;of a binary tree, return all <strong>duplicate subtrees</strong>.</p>
-
-<p>For each kind of duplicate subtrees, you only need to return the root node of any <b>one</b> of them.</p>
-
-<p>Two trees are <strong>duplicate</strong> if they have the <strong>same structure</strong> with the <strong>same node values</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/16/e1.jpg" style="width: 450px; height: 354px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,null,2,4,null,null,4]
-<strong>Output:</strong> [[2,4],[4]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/16/e2.jpg" style="width: 321px; height: 201px;" />
-<pre>
-<strong>Input:</strong> root = [2,1,1]
-<strong>Output:</strong> [[1]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/16/e33.jpg" style="width: 450px; height: 303px;" />
-<pre>
-<strong>Input:</strong> root = [2,2,2,3,null,3,null]
-<strong>Output:</strong> [[2,3],[3]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of the nodes in the tree will be in the range <code>[1, 10^4]</code></li>
-	<li><code>-200 &lt;= Node.val &lt;= 200</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Serialize and Deserialize Binary Tree](../serialize-and-deserialize-binary-tree) (Hard)
-  1. [Serialize and Deserialize BST](../serialize-and-deserialize-bst) (Medium)
-  1. [Construct String from Binary Tree](../construct-string-from-binary-tree) (Easy)
-  1. [Delete Duplicate Folders in System](../delete-duplicate-folders-in-system) (Hard)
diff --git a/problems/find-duplicate-subtrees/find_duplicate_subtrees.go b/problems/find-duplicate-subtrees/find_duplicate_subtrees.go
deleted file mode 100644
index a9a40c8be..000000000
--- a/problems/find-duplicate-subtrees/find_duplicate_subtrees.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem652
diff --git a/problems/find-duplicate-subtrees/find_duplicate_subtrees_test.go b/problems/find-duplicate-subtrees/find_duplicate_subtrees_test.go
deleted file mode 100644
index a9a40c8be..000000000
--- a/problems/find-duplicate-subtrees/find_duplicate_subtrees_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem652
diff --git a/problems/find-elements-in-a-contaminated-binary-tree/README.md b/problems/find-elements-in-a-contaminated-binary-tree/README.md
deleted file mode 100644
index c775ccfe2..000000000
--- a/problems/find-elements-in-a-contaminated-binary-tree/README.md
+++ /dev/null
@@ -1,102 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shift-2d-grid "Shift 2D Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../greatest-sum-divisible-by-three "Greatest Sum Divisible by Three")
-
-## [1261. Find Elements in a Contaminated Binary Tree (Medium)](https://leetcode.com/problems/find-elements-in-a-contaminated-binary-tree "在受污染的二叉树中查找元素")
-
-<p>Given a binary tree with the following rules:</p>
-
-<ol>
-	<li><code>root.val == 0</code></li>
-	<li>If <code>treeNode.val == x</code> and <code>treeNode.left != null</code>, then <code>treeNode.left.val == 2 * x + 1</code></li>
-	<li>If <code>treeNode.val == x</code> and <code>treeNode.right != null</code>, then <code>treeNode.right.val == 2 * x + 2</code></li>
-</ol>
-
-<p>Now the binary tree is contaminated, which means all <code>treeNode.val</code> have been changed to <code>-1</code>.</p>
-
-<p>Implement the <code>FindElements</code> class:</p>
-
-<ul>
-	<li><code>FindElements(TreeNode* root)</code> Initializes the object with a contaminated binary tree and recovers it.</li>
-	<li><code>bool find(int target)</code> Returns <code>true</code> if the <code>target</code> value exists in the recovered binary tree.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/06/untitled-diagram-4-1.jpg" style="width: 320px; height: 119px;" />
-<pre>
-<strong>Input</strong>
-[&quot;FindElements&quot;,&quot;find&quot;,&quot;find&quot;]
-[[[-1,null,-1]],[1],[2]]
-<strong>Output</strong>
-[null,false,true]
-<strong>Explanation</strong>
-FindElements findElements = new FindElements([-1,null,-1]); 
-findElements.find(1); // return False 
-findElements.find(2); // return True </pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/06/untitled-diagram-4.jpg" style="width: 400px; height: 198px;" />
-<pre>
-<strong>Input</strong>
-[&quot;FindElements&quot;,&quot;find&quot;,&quot;find&quot;,&quot;find&quot;]
-[[[-1,-1,-1,-1,-1]],[1],[3],[5]]
-<strong>Output</strong>
-[null,true,true,false]
-<strong>Explanation</strong>
-FindElements findElements = new FindElements([-1,-1,-1,-1,-1]);
-findElements.find(1); // return True
-findElements.find(3); // return True
-findElements.find(5); // return False</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/07/untitled-diagram-4-1-1.jpg" style="width: 306px; height: 274px;" />
-<pre>
-<strong>Input</strong>
-[&quot;FindElements&quot;,&quot;find&quot;,&quot;find&quot;,&quot;find&quot;,&quot;find&quot;]
-[[[-1,null,-1,-1,null,-1]],[2],[3],[4],[5]]
-<strong>Output</strong>
-[null,true,false,false,true]
-<strong>Explanation</strong>
-FindElements findElements = new FindElements([-1,null,-1,-1,null,-1]);
-findElements.find(2); // return True
-findElements.find(3); // return False
-findElements.find(4); // return False
-findElements.find(5); // return True
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>TreeNode.val == -1</code></li>
-	<li>The height of the binary tree is less than or equal to <code>20</code></li>
-	<li>The total number of nodes is between <code>[1, 10<sup>4</sup>]</code></li>
-	<li>Total calls of <code>find()</code> is between <code>[1, 10<sup>4</sup>]</code></li>
-	<li><code>0 &lt;= target &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use DFS to traverse the binary tree and recover it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a hashset to store TreeNode.val for finding.
-</details>
diff --git a/problems/find-eventual-safe-states/README.md b/problems/find-eventual-safe-states/README.md
deleted file mode 100644
index 5ed0ba863..000000000
--- a/problems/find-eventual-safe-states/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-swaps-to-make-sequences-increasing "Minimum Swaps To Make Sequences Increasing")
-　　　　　　　　　　　　　　　　
-[Next >](../bricks-falling-when-hit "Bricks Falling When Hit")
-
-## [802. Find Eventual Safe States (Medium)](https://leetcode.com/problems/find-eventual-safe-states "找到最终的安全状态")
-
-<p>There is a directed graph of <code>n</code> nodes with each node labeled from <code>0</code> to <code>n - 1</code>. The graph is represented by a <strong>0-indexed</strong> 2D integer array <code>graph</code> where <code>graph[i]</code> is an integer array of nodes adjacent to node <code>i</code>, meaning there is an edge from node <code>i</code> to each node in <code>graph[i]</code>.</p>
-
-<p>A node is a <strong>terminal node</strong> if there are no outgoing edges. A node is a <strong>safe node</strong> if every possible path starting from that node leads to a <strong>terminal node</strong>.</p>
-
-<p>Return <em>an array containing all the <strong>safe nodes</strong> of the graph</em>. The answer should be sorted in <strong>ascending</strong> order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="Illustration of graph" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/03/17/picture1.png" style="height: 171px; width: 600px;" />
-<pre>
-<strong>Input:</strong> graph = [[1,2],[2,3],[5],[0],[5],[],[]]
-<strong>Output:</strong> [2,4,5,6]
-<strong>Explanation:</strong> The given graph is shown above.
-Nodes 5 and 6 are terminal nodes as there are no outgoing edges from either of them.
-Every path starting at nodes 2, 4, 5, and 6 all lead to either node 5 or 6.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> graph = [[1,2,3,4],[1,2],[3,4],[0,4],[]]
-<strong>Output:</strong> [4]
-<strong>Explanation:</strong>
-Only node 4 is a terminal node, and every path starting at node 4 leads to node 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == graph.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= graph[i].length &lt;= n</code></li>
-	<li><code>0 &lt;= graph[i][j] &lt;= n - 1</code></li>
-	<li><code>graph[i]</code> is sorted in a strictly increasing order.</li>
-	<li>The graph may contain self-loops.</li>
-	<li>The number of edges in the graph will be in the range <code>[1, 4 * 10<sup>4</sup>]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
diff --git a/problems/find-eventual-safe-states/find_eventual_safe_states.go b/problems/find-eventual-safe-states/find_eventual_safe_states.go
deleted file mode 100644
index 3000b5856..000000000
--- a/problems/find-eventual-safe-states/find_eventual_safe_states.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem802
diff --git a/problems/find-eventual-safe-states/find_eventual_safe_states_test.go b/problems/find-eventual-safe-states/find_eventual_safe_states_test.go
deleted file mode 100644
index 3000b5856..000000000
--- a/problems/find-eventual-safe-states/find_eventual_safe_states_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem802
diff --git a/problems/find-first-and-last-position-of-element-in-sorted-array/README.md b/problems/find-first-and-last-position-of-element-in-sorted-array/README.md
deleted file mode 100644
index bc6e12886..000000000
--- a/problems/find-first-and-last-position-of-element-in-sorted-array/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../search-in-rotated-sorted-array "Search in Rotated Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../search-insert-position "Search Insert Position")
-
-## [34. Find First and Last Position of Element in Sorted Array (Medium)](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array "在排序数组中查找元素的第一个和最后一个位置")
-
-<p>Given an array of integers <code>nums</code> sorted in non-decreasing order, find the starting and ending position of a given <code>target</code> value.</p>
-
-<p>If <code>target</code> is not found in the array, return <code>[-1, -1]</code>.</p>
-
-<p>You must&nbsp;write an algorithm with&nbsp;<code>O(log n)</code> runtime complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [5,7,7,8,8,10], target = 8
-<strong>Output:</strong> [3,4]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [5,7,7,8,8,10], target = 6
-<strong>Output:</strong> [-1,-1]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [], target = 0
-<strong>Output:</strong> [-1,-1]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup>&nbsp;&lt;= nums[i]&nbsp;&lt;= 10<sup>9</sup></code></li>
-	<li><code>nums</code> is a non-decreasing array.</li>
-	<li><code>-10<sup>9</sup>&nbsp;&lt;= target&nbsp;&lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [First Bad Version](../first-bad-version) (Easy)
-  1. [Plates Between Candles](../plates-between-candles) (Medium)
-  1. [Find Target Indices After Sorting Array](../find-target-indices-after-sorting-array) (Easy)
diff --git a/problems/find-first-and-last-position-of-element-in-sorted-array/find_first_and_last_position_of_element_in_sorted_array.go b/problems/find-first-and-last-position-of-element-in-sorted-array/find_first_and_last_position_of_element_in_sorted_array.go
deleted file mode 100644
index 2f8bf93e4..000000000
--- a/problems/find-first-and-last-position-of-element-in-sorted-array/find_first_and_last_position_of_element_in_sorted_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem34
diff --git a/problems/find-first-and-last-position-of-element-in-sorted-array/find_first_and_last_position_of_element_in_sorted_array_test.go b/problems/find-first-and-last-position-of-element-in-sorted-array/find_first_and_last_position_of_element_in_sorted_array_test.go
deleted file mode 100644
index 2f8bf93e4..000000000
--- a/problems/find-first-and-last-position-of-element-in-sorted-array/find_first_and_last_position_of_element_in_sorted_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem34
diff --git a/problems/find-first-palindromic-string-in-the-array/README.md b/problems/find-first-palindromic-string-in-the-array/README.md
deleted file mode 100644
index d10defefd..000000000
--- a/problems/find-first-palindromic-string-in-the-array/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-unique-flavors-after-sharing-k-candies "Number of Unique Flavors After Sharing K Candies")
-　　　　　　　　　　　　　　　　
-[Next >](../adding-spaces-to-a-string "Adding Spaces to a String")
-
-## [2108. Find First Palindromic String in the Array (Easy)](https://leetcode.com/problems/find-first-palindromic-string-in-the-array "找出数组中的第一个回文字符串")
-
-<p>Given an array of strings <code>words</code>, return <em>the first <strong>palindromic</strong> string in the array</em>. If there is no such string, return <em>an <strong>empty string</strong> </em><code>&quot;&quot;</code>.</p>
-
-<p>A string is <strong>palindromic</strong> if it reads the same forward and backward.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;abc&quot;,&quot;car&quot;,&quot;ada&quot;,&quot;racecar&quot;,&quot;cool&quot;]
-<strong>Output:</strong> &quot;ada&quot;
-<strong>Explanation:</strong> The first string that is palindromic is &quot;ada&quot;.
-Note that &quot;racecar&quot; is also palindromic, but it is not the first.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;notapalindrome&quot;,&quot;racecar&quot;]
-<strong>Output:</strong> &quot;racecar&quot;
-<strong>Explanation:</strong> The first and only string that is palindromic is &quot;racecar&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;def&quot;,&quot;ghi&quot;]
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> There are no palindromic strings, so the empty string is returned.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 100</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 100</code></li>
-	<li><code>words[i]</code> consists only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate through the elements in order. As soon as the current element is a palindrome, return it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To check if an element is a palindrome, can you reverse the string?
-</details>
diff --git a/problems/find-followers-count/README.md b/problems/find-followers-count/README.md
deleted file mode 100644
index 296bbf93d..000000000
--- a/problems/find-followers-count/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cat-and-mouse-ii "Cat and Mouse II")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-path-to-get-food "Shortest Path to Get Food")
-
-## [1729. Find Followers Count (Easy)](https://leetcode.com/problems/find-followers-count "求关注者的数量")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/find-followers-count/mysql_schemas.sql b/problems/find-followers-count/mysql_schemas.sql
deleted file mode 100644
index dda0ddddf..000000000
--- a/problems/find-followers-count/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Followers(user_id int, follower_id int);
-Truncate table Followers;
-insert into Followers (user_id, follower_id) values ('0', '1');
-insert into Followers (user_id, follower_id) values ('1', '0');
-insert into Followers (user_id, follower_id) values ('2', '0');
-insert into Followers (user_id, follower_id) values ('2', '1');
diff --git a/problems/find-good-days-to-rob-the-bank/README.md b/problems/find-good-days-to-rob-the-bank/README.md
deleted file mode 100644
index 0f8c76b53..000000000
--- a/problems/find-good-days-to-rob-the-bank/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-subsequence-of-length-k-with-the-largest-sum "Find Subsequence of Length K With the Largest Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../detonate-the-maximum-bombs "Detonate the Maximum Bombs")
-
-## [2100. Find Good Days to Rob the Bank (Medium)](https://leetcode.com/problems/find-good-days-to-rob-the-bank "适合打劫银行的日子")
-
-<p>You and a gang of thieves are planning on robbing a bank. You are given a <strong>0-indexed</strong> integer array <code>security</code>, where <code>security[i]</code> is the number of guards on duty on the <code>i<sup>th</sup></code> day. The days are numbered starting from <code>0</code>. You are also given an integer <code>time</code>.</p>
-
-<p>The <code>i<sup>th</sup></code> day is a good day to rob the bank if:</p>
-
-<ul>
-	<li>There are at least <code>time</code> days before and after the <code>i<sup>th</sup></code> day,</li>
-	<li>The number of guards at the bank for the <code>time</code> days <strong>before</strong> <code>i</code> are <strong>non-increasing</strong>, and</li>
-	<li>The number of guards at the bank for the <code>time</code> days <strong>after</strong> <code>i</code> are <strong>non-decreasing</strong>.</li>
-</ul>
-
-<p>More formally, this means day <code>i</code> is a good day to rob the bank if and only if <code>security[i - time] &gt;= security[i - time + 1] &gt;= ... &gt;= security[i] &lt;= ... &lt;= security[i + time - 1] &lt;= security[i + time]</code>.</p>
-
-<p>Return <em>a list of <strong>all</strong> days <strong>(0-indexed) </strong>that are good days to rob the bank</em>.<em> The order that the days are returned in does<strong> </strong><strong>not</strong> matter.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> security = [5,3,3,3,5,6,2], time = 2
-<strong>Output:</strong> [2,3]
-<strong>Explanation:</strong>
-On day 2, we have security[0] &gt;= security[1] &gt;= security[2] &lt;= security[3] &lt;= security[4].
-On day 3, we have security[1] &gt;= security[2] &gt;= security[3] &lt;= security[4] &lt;= security[5].
-No other days satisfy this condition, so days 2 and 3 are the only good days to rob the bank.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> security = [1,1,1,1,1], time = 0
-<strong>Output:</strong> [0,1,2,3,4]
-<strong>Explanation:</strong>
-Since time equals 0, every day is a good day to rob the bank, so return every day.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> security = [1,2,3,4,5,6], time = 2
-<strong>Output:</strong> []
-<strong>Explanation:</strong>
-No day has 2 days before it that have a non-increasing number of guards.
-Thus, no day is a good day to rob the bank, so return an empty list.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= security.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= security[i], time &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The trivial solution is to check the time days before and after each day. There are a lot of repeated operations using this solution. How could we optimize this solution?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can use precomputation to make the solution faster.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use an array to store the number of days before the i<sup>th</sup> day that is non-increasing, and another array to store the number of days after the i<sup>th</sup> day that is non-decreasing.
-</details>
diff --git a/problems/find-greatest-common-divisor-of-array/README.md b/problems/find-greatest-common-divisor-of-array/README.md
deleted file mode 100644
index 0aca50aaa..000000000
--- a/problems/find-greatest-common-divisor-of-array/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../employees-whose-manager-left-the-company "Employees Whose Manager Left the Company")
-　　　　　　　　　　　　　　　　
-[Next >](../find-unique-binary-string "Find Unique Binary String")
-
-## [1979. Find Greatest Common Divisor of Array (Easy)](https://leetcode.com/problems/find-greatest-common-divisor-of-array "找出数组的最大公约数")
-
-<p>Given an integer array <code>nums</code>, return<strong> </strong><em>the <strong>greatest common divisor</strong> of the smallest number and largest number in </em><code>nums</code>.</p>
-
-<p>The <strong>greatest common divisor</strong> of two numbers is the largest positive integer that evenly divides both numbers.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,5,6,9,10]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-The smallest number in nums is 2.
-The largest number in nums is 10.
-The greatest common divisor of 2 and 10 is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,5,6,8,3]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-The smallest number in nums is 3.
-The largest number in nums is 8.
-The greatest common divisor of 3 and 8 is 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-The smallest number in nums is 3.
-The largest number in nums is 3.
-The greatest common divisor of 3 and 3 is 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the minimum and maximum in one iteration. Let them be mn and mx.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try all the numbers in the range [1, mn] and check the largest number which divides both of them.
-</details>
diff --git a/problems/find-if-path-exists-in-graph/README.md b/problems/find-if-path-exists-in-graph/README.md
deleted file mode 100644
index f0623ec1c..000000000
--- a/problems/find-if-path-exists-in-graph/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../last-day-where-you-can-still-cross "Last Day Where You Can Still Cross")
-　　　　　　　　　　　　　　　　
-[Next >](../first-and-last-call-on-the-same-day "First and Last Call On the Same Day")
-
-## [1971. Find if Path Exists in Graph (Easy)](https://leetcode.com/problems/find-if-path-exists-in-graph "寻找图中是否存在路径")
-
-<p>There is a <strong>bi-directional</strong> graph with <code>n</code> vertices, where each vertex is labeled from <code>0</code> to <code>n - 1</code> (<strong>inclusive</strong>). The edges in the graph are represented as a 2D integer array <code>edges</code>, where each <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> denotes a bi-directional edge between vertex <code>u<sub>i</sub></code> and vertex <code>v<sub>i</sub></code>. Every vertex pair is connected by <strong>at most one</strong> edge, and no vertex has an edge to itself.</p>
-
-<p>You want to determine if there is a <strong>valid path</strong> that exists from vertex <code>source</code> to vertex <code>destination</code>.</p>
-
-<p>Given <code>edges</code> and the integers <code>n</code>, <code>source</code>, and <code>destination</code>, return <code>true</code><em> if there is a <strong>valid path</strong> from </em><code>source</code><em> to </em><code>destination</code><em>, or </em><code>false</code><em> otherwise</em><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/14/validpath-ex1.png" style="width: 141px; height: 121px;" />
-<pre>
-<strong>Input:</strong> n = 3, edges = [[0,1],[1,2],[2,0]], source = 0, destination = 2
-<strong>Output:</strong> true
-<strong>Explanation:</strong> There are two paths from vertex 0 to vertex 2:
-- 0 &rarr; 1 &rarr; 2
-- 0 &rarr; 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/14/validpath-ex2.png" style="width: 281px; height: 141px;" />
-<pre>
-<strong>Input:</strong> n = 6, edges = [[0,1],[0,2],[3,5],[5,4],[4,3]], source = 0, destination = 5
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There is no path from vertex 0 to vertex 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= edges.length &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>0 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>u<sub>i</sub> != v<sub>i</sub></code></li>
-	<li><code>0 &lt;= source, destination &lt;= n - 1</code></li>
-	<li>There are no duplicate edges.</li>
-	<li>There are no self edges.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
diff --git a/problems/find-in-mountain-array/README.md b/problems/find-in-mountain-array/README.md
deleted file mode 100644
index 972eb7790..000000000
--- a/problems/find-in-mountain-array/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../car-pooling "Car Pooling")
-　　　　　　　　　　　　　　　　
-[Next >](../brace-expansion-ii "Brace Expansion II")
-
-## [1095. Find in Mountain Array (Hard)](https://leetcode.com/problems/find-in-mountain-array "山脉数组中查找目标值")
-
-<p><em>(This problem is an <strong>interactive problem</strong>.)</em></p>
-
-<p>You may recall that an array <code>arr</code> is a <strong>mountain array</strong> if and only if:</p>
-
-<ul>
-	<li><code>arr.length &gt;= 3</code></li>
-	<li>There exists some <code>i</code> with <code>0 &lt; i &lt; arr.length - 1</code> such that:
-	<ul>
-		<li><code>arr[0] &lt; arr[1] &lt; ... &lt; arr[i - 1] &lt; arr[i]</code></li>
-		<li><code>arr[i] &gt; arr[i + 1] &gt; ... &gt; arr[arr.length - 1]</code></li>
-	</ul>
-	</li>
-</ul>
-
-<p>Given a mountain array <code>mountainArr</code>, return the <strong>minimum</strong> <code>index</code> such that <code>mountainArr.get(index) == target</code>. If such an <code>index</code> does not exist, return <code>-1</code>.</p>
-
-<p><strong>You cannot access the mountain array directly.</strong> You may only access the array using a <code>MountainArray</code> interface:</p>
-
-<ul>
-	<li><code>MountainArray.get(k)</code> returns the element of the array at index <code>k</code> (0-indexed).</li>
-	<li><code>MountainArray.length()</code> returns the length of the array.</li>
-</ul>
-
-<p>Submissions making more than <code>100</code> calls to <code>MountainArray.get</code> will be judged <em>Wrong Answer</em>. Also, any solutions that attempt to circumvent the judge will result in disqualification.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> array = [1,2,3,4,5,3,1], target = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 3 exists in the array, at index=2 and index=5. Return the minimum index, which is 2.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> array = [0,1,2,4,2,1], target = 3
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> 3 does not exist in <code>the array,</code> so we return -1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= mountain_arr.length() &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= target &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= mountain_arr.get(index) &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Similar Questions
-  1. [Peak Index in a Mountain Array](../peak-index-in-a-mountain-array) (Easy)
-  1. [Minimum Number of Removals to Make Mountain Array](../minimum-number-of-removals-to-make-mountain-array) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Based on whether A[i-1] < A[i] < A[i+1], A[i-1] < A[i] > A[i+1], or A[i-1] > A[i] > A[i+1], we are either at the left side, peak, or right side of the mountain.  We can binary search to find the peak.
-After finding the peak, we can binary search two more times to find whether the value occurs on either side of the peak.
-</details>
diff --git a/problems/find-in-mountain-array/find_in_mountain_array.go b/problems/find-in-mountain-array/find_in_mountain_array.go
deleted file mode 100644
index 536e1c4a2..000000000
--- a/problems/find-in-mountain-array/find_in_mountain_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1095
diff --git a/problems/find-interview-candidates/README.md b/problems/find-interview-candidates/README.md
deleted file mode 100644
index 660d053e7..000000000
--- a/problems/find-interview-candidates/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-path-cost-in-a-hidden-grid "Minimum Path Cost in a Hidden Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../determine-color-of-a-chessboard-square "Determine Color of a Chessboard Square")
-
-## [1811. Find Interview Candidates (Medium)](https://leetcode.com/problems/find-interview-candidates "寻找面试候选人")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/find-interview-candidates/mysql_schemas.sql b/problems/find-interview-candidates/mysql_schemas.sql
deleted file mode 100644
index bfd4e69c8..000000000
--- a/problems/find-interview-candidates/mysql_schemas.sql
+++ /dev/null
@@ -1,16 +0,0 @@
-Create table If Not Exists Contests (contest_id int, gold_medal int, silver_medal int, bronze_medal int);
-Create table If Not Exists Users (user_id int, mail varchar(50), name varchar(30));
-Truncate table Contests;
-insert into Contests (contest_id, gold_medal, silver_medal, bronze_medal) values ('190', '1', '5', '2');
-insert into Contests (contest_id, gold_medal, silver_medal, bronze_medal) values ('191', '2', '3', '5');
-insert into Contests (contest_id, gold_medal, silver_medal, bronze_medal) values ('192', '5', '2', '3');
-insert into Contests (contest_id, gold_medal, silver_medal, bronze_medal) values ('193', '1', '3', '5');
-insert into Contests (contest_id, gold_medal, silver_medal, bronze_medal) values ('194', '4', '5', '2');
-insert into Contests (contest_id, gold_medal, silver_medal, bronze_medal) values ('195', '4', '2', '1');
-insert into Contests (contest_id, gold_medal, silver_medal, bronze_medal) values ('196', '1', '5', '2');
-Truncate table Users;
-insert into Users (user_id, mail, name) values ('1', 'sarah@leetcode.com', 'Sarah');
-insert into Users (user_id, mail, name) values ('2', 'bob@leetcode.com', 'Bob');
-insert into Users (user_id, mail, name) values ('3', 'alice@leetcode.com', 'Alice');
-insert into Users (user_id, mail, name) values ('4', 'hercy@leetcode.com', 'Hercy');
-insert into Users (user_id, mail, name) values ('5', 'quarz@leetcode.com', 'Quarz');
diff --git a/problems/find-k-closest-elements/README.md b/problems/find-k-closest-elements/README.md
deleted file mode 100644
index 3256c0ea8..000000000
--- a/problems/find-k-closest-elements/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../robot-return-to-origin "Robot Return to Origin")
-　　　　　　　　　　　　　　　　
-[Next >](../split-array-into-consecutive-subsequences "Split Array into Consecutive Subsequences")
-
-## [658. Find K Closest Elements (Medium)](https://leetcode.com/problems/find-k-closest-elements "找到 K 个最接近的元素")
-
-<p>Given a <strong>sorted</strong> integer array <code>arr</code>, two integers <code>k</code> and <code>x</code>, return the <code>k</code> closest integers to <code>x</code> in the array. The result should also be sorted in ascending order.</p>
-
-<p>An integer <code>a</code> is closer to <code>x</code> than an integer <code>b</code> if:</p>
-
-<ul>
-	<li><code>|a - x| &lt; |b - x|</code>, or</li>
-	<li><code>|a - x| == |b - x|</code> and <code>a &lt; b</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> arr = [1,2,3,4,5], k = 4, x = 3
-<strong>Output:</strong> [1,2,3,4]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> arr = [1,2,3,4,5], k = 4, x = -1
-<strong>Output:</strong> [1,2,3,4]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= arr.length</code></li>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>arr</code> is sorted in <strong>ascending</strong> order.</li>
-	<li><code>-10<sup>4</sup> &lt;= arr[i], x &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Guess Number Higher or Lower](../guess-number-higher-or-lower) (Easy)
-  1. [Guess Number Higher or Lower II](../guess-number-higher-or-lower-ii) (Medium)
-  1. [Find K-th Smallest Pair Distance](../find-k-th-smallest-pair-distance) (Hard)
diff --git a/problems/find-k-closest-elements/find_k_closest_elements.go b/problems/find-k-closest-elements/find_k_closest_elements.go
deleted file mode 100644
index 50cf6a5aa..000000000
--- a/problems/find-k-closest-elements/find_k_closest_elements.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem658
diff --git a/problems/find-k-closest-elements/find_k_closest_elements_test.go b/problems/find-k-closest-elements/find_k_closest_elements_test.go
deleted file mode 100644
index 50cf6a5aa..000000000
--- a/problems/find-k-closest-elements/find_k_closest_elements_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem658
diff --git a/problems/find-k-length-substrings-with-no-repeated-characters/README.md b/problems/find-k-length-substrings-with-no-repeated-characters/README.md
deleted file mode 100644
index 2ffabda34..000000000
--- a/problems/find-k-length-substrings-with-no-repeated-characters/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-sum-less-than-k "Two Sum Less Than K")
-　　　　　　　　　　　　　　　　
-[Next >](../the-earliest-moment-when-everyone-become-friends "The Earliest Moment When Everyone Become Friends")
-
-## [1100. Find K-Length Substrings With No Repeated Characters (Medium)](https://leetcode.com/problems/find-k-length-substrings-with-no-repeated-characters "长度为 K 的无重复字符子串")
-
-<p>Given a string <code>S</code>, return the number of substrings of length <code>K</code> with no repeated characters.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>S = <span id="example-input-1-1">&quot;havefunonleetcode&quot;</span>, K = <span id="example-input-1-2">5</span>
-<strong>Output: </strong><span id="example-output-1">6</span>
-<strong>Explanation: </strong>
-There are 6 substrings they are : &#39;havef&#39;,&#39;avefu&#39;,&#39;vefun&#39;,&#39;efuno&#39;,&#39;etcod&#39;,&#39;tcode&#39;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>S = <span id="example-input-2-1">&quot;home&quot;</span>, K = <span id="example-input-2-2">5</span>
-<strong>Output: </strong><span id="example-output-2">0</span>
-<strong>Explanation: </strong>
-Notice K can be larger than the length of S. In this case is not possible to find any substring.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= S.length &lt;= 10^4</code></li>
-	<li>All characters of S are lowercase English letters.</li>
-	<li><code>1 &lt;= K &lt;= 10^4</code></li>
-</ol>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to check efficiently each K-length substring?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-First store the first leftmost K-length substring in a hashTable or array of frequencies.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Then iterate through the rest of characters and erase the first element and add the next element from the right. If in the hashTable we have K different character we add 1 to the counter. After that return as answer the counter.
-</details>
diff --git a/problems/find-k-pairs-with-smallest-sums/README.md b/problems/find-k-pairs-with-smallest-sums/README.md
deleted file mode 100644
index 34da2c164..000000000
--- a/problems/find-k-pairs-with-smallest-sums/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../super-pow "Super Pow")
-　　　　　　　　　　　　　　　　
-[Next >](../guess-number-higher-or-lower "Guess Number Higher or Lower")
-
-## [373. Find K Pairs with Smallest Sums (Medium)](https://leetcode.com/problems/find-k-pairs-with-smallest-sums "查找和最小的K对数字")
-
-<p>You are given two integer arrays <code>nums1</code> and <code>nums2</code> sorted in <strong>ascending order</strong> and an integer <code>k</code>.</p>
-
-<p>Define a pair <code>(u, v)</code> which consists of one element from the first array and one element from the second array.</p>
-
-<p>Return <em>the</em> <code>k</code> <em>pairs</em> <code>(u<sub>1</sub>, v<sub>1</sub>), (u<sub>2</sub>, v<sub>2</sub>), ..., (u<sub>k</sub>, v<sub>k</sub>)</code> <em>with the smallest sums</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,7,11], nums2 = [2,4,6], k = 3
-<strong>Output:</strong> [[1,2],[1,4],[1,6]]
-<strong>Explanation:</strong> The first 3 pairs are returned from the sequence: [1,2],[1,4],[1,6],[7,2],[7,4],[11,2],[7,6],[11,4],[11,6]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,1,2], nums2 = [1,2,3], k = 2
-<strong>Output:</strong> [[1,1],[1,1]]
-<strong>Explanation:</strong> The first 2 pairs are returned from the sequence: [1,1],[1,1],[1,2],[2,1],[1,2],[2,2],[1,3],[1,3],[2,3]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2], nums2 = [3], k = 3
-<strong>Output:</strong> [[1,3],[2,3]]
-<strong>Explanation:</strong> All possible pairs are returned from the sequence: [1,3],[2,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums1[i], nums2[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>nums1</code> and <code>nums2</code> both are sorted in <strong>ascending order</strong>.</li>
-	<li><code>1 &lt;= k &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Kth Smallest Element in a Sorted Matrix](../kth-smallest-element-in-a-sorted-matrix) (Medium)
-  1. [Find K-th Smallest Pair Distance](../find-k-th-smallest-pair-distance) (Hard)
-  1. [Kth Smallest Product of Two Sorted Arrays](../kth-smallest-product-of-two-sorted-arrays) (Hard)
diff --git a/problems/find-k-pairs-with-smallest-sums/find_k_pairs_with_smallest_sums.go b/problems/find-k-pairs-with-smallest-sums/find_k_pairs_with_smallest_sums.go
deleted file mode 100644
index 04bb844dd..000000000
--- a/problems/find-k-pairs-with-smallest-sums/find_k_pairs_with_smallest_sums.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem373
diff --git a/problems/find-k-pairs-with-smallest-sums/find_k_pairs_with_smallest_sums_test.go b/problems/find-k-pairs-with-smallest-sums/find_k_pairs_with_smallest_sums_test.go
deleted file mode 100644
index 04bb844dd..000000000
--- a/problems/find-k-pairs-with-smallest-sums/find_k_pairs_with_smallest_sums_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem373
diff --git a/problems/find-k-th-smallest-pair-distance/README.md b/problems/find-k-th-smallest-pair-distance/README.md
deleted file mode 100644
index 7edbcfaf5..000000000
--- a/problems/find-k-th-smallest-pair-distance/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-length-of-repeated-subarray "Maximum Length of Repeated Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-word-in-dictionary "Longest Word in Dictionary")
-
-## [719. Find K-th Smallest Pair Distance (Hard)](https://leetcode.com/problems/find-k-th-smallest-pair-distance "找出第 k 小的距离对")
-
-<p>The <strong>distance of a pair</strong> of integers <code>a</code> and <code>b</code> is defined as the absolute difference between <code>a</code> and <code>b</code>.</p>
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the</em> <code>k<sup>th</sup></code> <em>smallest <strong>distance among all the pairs</strong></em> <code>nums[i]</code> <em>and</em> <code>nums[j]</code> <em>where</em> <code>0 &lt;= i &lt; j &lt; nums.length</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,1], k = 1
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Here are all the pairs:
-(1,3) -&gt; 2
-(1,1) -&gt; 0
-(3,1) -&gt; 2
-Then the 1<sup>st</sup> smallest distance pair is (1,1), and its distance is 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1], k = 2
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,6,1], k = 3
-<strong>Output:</strong> 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= k &lt;= n * (n - 1) / 2</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Find K Pairs with Smallest Sums](../find-k-pairs-with-smallest-sums) (Medium)
-  1. [Kth Smallest Element in a Sorted Matrix](../kth-smallest-element-in-a-sorted-matrix) (Medium)
-  1. [Find K Closest Elements](../find-k-closest-elements) (Medium)
-  1. [Kth Smallest Number in Multiplication Table](../kth-smallest-number-in-multiplication-table) (Hard)
-  1. [K-th Smallest Prime Fraction](../k-th-smallest-prime-fraction) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Binary search for the answer.  How can you check how many pairs have distance <= X?
-</details>
diff --git a/problems/find-k-th-smallest-pair-distance/find_k_th_smallest_pair_distance.go b/problems/find-k-th-smallest-pair-distance/find_k_th_smallest_pair_distance.go
deleted file mode 100644
index b54abe8d2..000000000
--- a/problems/find-k-th-smallest-pair-distance/find_k_th_smallest_pair_distance.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem719
diff --git a/problems/find-k-th-smallest-pair-distance/find_k_th_smallest_pair_distance_test.go b/problems/find-k-th-smallest-pair-distance/find_k_th_smallest_pair_distance_test.go
deleted file mode 100644
index b54abe8d2..000000000
--- a/problems/find-k-th-smallest-pair-distance/find_k_th_smallest_pair_distance_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem719
diff --git a/problems/find-kth-bit-in-nth-binary-string/README.md b/problems/find-kth-bit-in-nth-binary-string/README.md
deleted file mode 100644
index a3be3ef9b..000000000
--- a/problems/find-kth-bit-in-nth-binary-string/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../make-the-string-great "Make The String Great")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-non-overlapping-subarrays-with-sum-equals-target "Maximum Number of Non-Overlapping Subarrays With Sum Equals Target")
-
-## [1545. Find Kth Bit in Nth Binary String (Medium)](https://leetcode.com/problems/find-kth-bit-in-nth-binary-string "找出第 N 个二进制字符串中的第 K 位")
-
-<p>Given two positive integers <code>n</code> and <code>k</code>, the binary string <code>S<sub>n</sub></code> is formed as follows:</p>
-
-<ul>
-	<li><code>S<sub>1</sub> = &quot;0&quot;</code></li>
-	<li><code>S<sub>i</sub> = S<sub>i - 1</sub> + &quot;1&quot; + reverse(invert(S<sub>i - 1</sub>))</code> for <code>i &gt; 1</code></li>
-</ul>
-
-<p>Where <code>+</code> denotes the concatenation operation, <code>reverse(x)</code> returns the reversed string <code>x</code>, and <code>invert(x)</code> inverts all the bits in <code>x</code> (<code>0</code> changes to <code>1</code> and <code>1</code> changes to <code>0</code>).</p>
-
-<p>For example, the first four strings in the above sequence are:</p>
-
-<ul>
-	<li><code>S<sub>1 </sub>= &quot;0&quot;</code></li>
-	<li><code>S<sub>2 </sub>= &quot;0<strong>1</strong>1&quot;</code></li>
-	<li><code>S<sub>3 </sub>= &quot;011<strong>1</strong>001&quot;</code></li>
-	<li><code>S<sub>4</sub> = &quot;0111001<strong>1</strong>0110001&quot;</code></li>
-</ul>
-
-<p>Return <em>the</em> <code>k<sup>th</sup></code> <em>bit</em> <em>in</em> <code>S<sub>n</sub></code>. It is guaranteed that <code>k</code> is valid for the given <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 1
-<strong>Output:</strong> &quot;0&quot;
-<strong>Explanation:</strong> S<sub>3</sub> is &quot;<strong><u>0</u></strong>111001&quot;.
-The 1<sup>st</sup> bit is &quot;0&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, k = 11
-<strong>Output:</strong> &quot;1&quot;
-<strong>Explanation:</strong> S<sub>4</sub> is &quot;0111001101<strong><u>1</u></strong>0001&quot;.
-The 11<sup>th</sup> bit is &quot;1&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-	<li><code>1 &lt;= k &lt;= 2<sup>n</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since n is small, we can simply simulate the process of constructing S1 to Sn.
-</details>
diff --git a/problems/find-kth-largest-xor-coordinate-value/README.md b/problems/find-kth-largest-xor-coordinate-value/README.md
deleted file mode 100644
index 1e1e0f942..000000000
--- a/problems/find-kth-largest-xor-coordinate-value/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../change-minimum-characters-to-satisfy-one-of-three-conditions "Change Minimum Characters to Satisfy One of Three Conditions")
-　　　　　　　　　　　　　　　　
-[Next >](../building-boxes "Building Boxes")
-
-## [1738. Find Kth Largest XOR Coordinate Value (Medium)](https://leetcode.com/problems/find-kth-largest-xor-coordinate-value "找出第 K 大的异或坐标值")
-
-<p>You are given a 2D <code>matrix</code> of size <code>m x n</code>, consisting of non-negative integers. You are also given an integer <code>k</code>.</p>
-
-<p>The <strong>value</strong> of coordinate <code>(a, b)</code> of the matrix is the XOR of all <code>matrix[i][j]</code> where <code>0 &lt;= i &lt;= a &lt; m</code> and <code>0 &lt;= j &lt;= b &lt; n</code> <strong>(0-indexed)</strong>.</p>
-
-<p>Find the <code>k<sup>th</sup></code> largest value <strong>(1-indexed)</strong> of all the coordinates of <code>matrix</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[5,2],[1,6]], k = 1
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The value of coordinate (0,1) is 5 XOR 2 = 7, which is the largest value.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[5,2],[1,6]], k = 2
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The value of coordinate (0,0) is 5 = 5, which is the 2nd largest value.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[5,2],[1,6]], k = 3
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The value of coordinate (1,0) is 5 XOR 1 = 4, which is the 3rd largest value.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 1000</code></li>
-	<li><code>0 &lt;= matrix[i][j] &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= k &lt;= m * n</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Quickselect](../../tag/quickselect/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a 2D prefix sum to precalculate the xor-sum of the upper left submatrix.
-</details>
diff --git a/problems/find-largest-value-in-each-tree-row/README.md b/problems/find-largest-value-in-each-tree-row/README.md
deleted file mode 100644
index 28388634d..000000000
--- a/problems/find-largest-value-in-each-tree-row/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../freedom-trail "Freedom Trail")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-palindromic-subsequence "Longest Palindromic Subsequence")
-
-## [515. Find Largest Value in Each Tree Row (Medium)](https://leetcode.com/problems/find-largest-value-in-each-tree-row "在每个树行中找最大值")
-
-<p>Given the <code>root</code> of a binary tree, return <em>an array of the largest value in each row</em> of the tree <strong>(0-indexed)</strong>.</p>
-
-<p>&nbsp;</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/21/largest_e1.jpg" style="width: 450px; height: 258px;" />
-<pre>
-<strong>Input:</strong> root = [1,3,2,5,3,null,9]
-<strong>Output:</strong> [1,3,9]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,2,3]
-<strong>Output:</strong> [1,3]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,2]
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree will be in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>-2<sup>31</sup> &lt;= Node.val &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/find-largest-value-in-each-tree-row/find_largest_value_in_each_tree_row.go b/problems/find-largest-value-in-each-tree-row/find_largest_value_in_each_tree_row.go
deleted file mode 100644
index 9503b7e30..000000000
--- a/problems/find-largest-value-in-each-tree-row/find_largest_value_in_each_tree_row.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem515
diff --git a/problems/find-largest-value-in-each-tree-row/find_largest_value_in_each_tree_row_test.go b/problems/find-largest-value-in-each-tree-row/find_largest_value_in_each_tree_row_test.go
deleted file mode 100644
index 9503b7e30..000000000
--- a/problems/find-largest-value-in-each-tree-row/find_largest_value_in_each_tree_row_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem515
diff --git a/problems/find-latest-group-of-size-m/README.md b/problems/find-latest-group-of-size-m/README.md
deleted file mode 100644
index a9082fdad..000000000
--- a/problems/find-latest-group-of-size-m/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-coins-you-can-get "Maximum Number of Coins You Can Get")
-　　　　　　　　　　　　　　　　
-[Next >](../stone-game-v "Stone Game V")
-
-## [1562. Find Latest Group of Size M (Medium)](https://leetcode.com/problems/find-latest-group-of-size-m "查找大小为 M 的最新分组")
-
-<p>Given an array <code>arr</code> that represents a permutation of numbers from <code>1</code> to <code>n</code>.</p>
-
-<p>You have a binary string of size <code>n</code> that initially has all its bits set to zero. At each step <code>i</code> (assuming both the binary string and <code>arr</code> are 1-indexed) from <code>1</code> to <code>n</code>, the bit at position <code>arr[i]</code> is set to <code>1</code>.</p>
-
-<p>You are also given an integer <code>m</code>. Find the latest step at which there exists a group of ones of length <code>m</code>. A group of ones is a contiguous substring of <code>1</code>&#39;s such that it cannot be extended in either direction.</p>
-
-<p>Return <em>the latest step at which there exists a group of ones of length <strong>exactly</strong></em> <code>m</code>. <em>If no such group exists, return</em> <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,5,1,2,4], m = 1
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> 
-Step 1: &quot;00<u>1</u>00&quot;, groups: [&quot;1&quot;]
-Step 2: &quot;0010<u>1</u>&quot;, groups: [&quot;1&quot;, &quot;1&quot;]
-Step 3: &quot;<u>1</u>0101&quot;, groups: [&quot;1&quot;, &quot;1&quot;, &quot;1&quot;]
-Step 4: &quot;1<u>1</u>101&quot;, groups: [&quot;111&quot;, &quot;1&quot;]
-Step 5: &quot;111<u>1</u>1&quot;, groups: [&quot;11111&quot;]
-The latest step at which there exists a group of size 1 is step 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,1,5,4,2], m = 2
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> 
-Step 1: &quot;00<u>1</u>00&quot;, groups: [&quot;1&quot;]
-Step 2: &quot;<u>1</u>0100&quot;, groups: [&quot;1&quot;, &quot;1&quot;]
-Step 3: &quot;1010<u>1</u>&quot;, groups: [&quot;1&quot;, &quot;1&quot;, &quot;1&quot;]
-Step 4: &quot;101<u>1</u>1&quot;, groups: [&quot;1&quot;, &quot;111&quot;]
-Step 5: &quot;1<u>1</u>111&quot;, groups: [&quot;11111&quot;]
-No group of size 2 exists during any step.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == arr.length</code></li>
-	<li><code>1 &lt;= m &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= n</code></li>
-	<li>All integers in <code>arr</code> are <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since the problem asks for the latest step, can you start the searching from the end of arr?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a map to store the current “1” groups.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-At each step (going backwards) you need to split one group and update the map.
-</details>
diff --git a/problems/find-leaves-of-binary-tree/README.md b/problems/find-leaves-of-binary-tree/README.md
deleted file mode 100644
index 581997b73..000000000
--- a/problems/find-leaves-of-binary-tree/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../water-and-jug-problem "Water and Jug Problem")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-perfect-square "Valid Perfect Square")
-
-## [366. Find Leaves of Binary Tree (Medium)](https://leetcode.com/problems/find-leaves-of-binary-tree "寻找二叉树的叶子节点")
-
-<p>Given a binary tree, collect a tree&#39;s nodes as if you were doing this: Collect and remove all leaves, repeat until the tree is empty.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[1,2,3,4,5]
-&nbsp; 
-&nbsp;         </span>1
-         / \
-        2   3
-       / \     
-      4   5    
-
-<strong>Output: </strong><span id="example-output-1">[[4,5,3],[2],[1]]</span>
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Explanation:</strong></p>
-
-<p>1. Removing the leaves <code>[4,5,3]</code> would result in this tree:</p>
-
-<pre>
-          1
-         / 
-        2          
-</pre>
-
-<p>&nbsp;</p>
-
-<p>2. Now removing the leaf <code>[2]</code> would result in this tree:</p>
-
-<pre>
-          1          
-</pre>
-
-<p>&nbsp;</p>
-
-<p>3. Now removing the leaf <code>[1]</code> would result in the empty tree:</p>
-
-<pre>
-          []         
-</pre>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/find-leaves-of-binary-tree/find_leaves_of_binary_tree.go b/problems/find-leaves-of-binary-tree/find_leaves_of_binary_tree.go
deleted file mode 100644
index 50a1d0f6b..000000000
--- a/problems/find-leaves-of-binary-tree/find_leaves_of_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem366
diff --git a/problems/find-leaves-of-binary-tree/find_leaves_of_binary_tree_test.go b/problems/find-leaves-of-binary-tree/find_leaves_of_binary_tree_test.go
deleted file mode 100644
index 50a1d0f6b..000000000
--- a/problems/find-leaves-of-binary-tree/find_leaves_of_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem366
diff --git a/problems/find-longest-awesome-substring/README.md b/problems/find-longest-awesome-substring/README.md
deleted file mode 100644
index b024ca96d..000000000
--- a/problems/find-longest-awesome-substring/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-insertions-to-balance-a-parentheses-string "Minimum Insertions to Balance a Parentheses String")
-　　　　　　　　　　　　　　　　
-[Next >](../fix-product-name-format "Fix Product Name Format")
-
-## [1542. Find Longest Awesome Substring (Hard)](https://leetcode.com/problems/find-longest-awesome-substring "找出最长的超赞子字符串")
-
-<p>You are given a string <code>s</code>. An <strong>awesome</strong> substring is a non-empty substring of <code>s</code> such that we can make any number of swaps in order to make it a palindrome.</p>
-
-<p>Return <em>the length of the maximum length <strong>awesome substring</strong> of</em> <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;3242415&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> &quot;24241&quot; is the longest awesome substring, we can form the palindrome &quot;24142&quot; with some swaps.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;12345678&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;213123&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> &quot;213123&quot; is the longest awesome substring, we can form the palindrome &quot;231132&quot; with some swaps.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists only of digits.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given the character counts, under what conditions can a palindrome be formed ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-From left to right, use bitwise xor-operation to compute for any prefix the number of times modulo 2 of each digit.  (mask ^= (1<<(s[i]-'0')).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Expected complexity is O(n*A) where A is the alphabet (10).
-</details>
diff --git a/problems/find-lucky-integer-in-an-array/README.md b/problems/find-lucky-integer-in-an-array/README.md
deleted file mode 100644
index 197c818bd..000000000
--- a/problems/find-lucky-integer-in-an-array/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../capital-gainloss "Capital Gain/Loss")
-　　　　　　　　　　　　　　　　
-[Next >](../count-number-of-teams "Count Number of Teams")
-
-## [1394. Find Lucky Integer in an Array (Easy)](https://leetcode.com/problems/find-lucky-integer-in-an-array "找出数组中的幸运数")
-
-<p>Given an array of integers <code>arr</code>, a <strong>lucky integer</strong> is an integer that has a frequency in the array equal to its value.</p>
-
-<p>Return <em>the largest <strong>lucky integer</strong> in the array</em>. If there is no <strong>lucky integer</strong> return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,2,3,4]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The only lucky number in the array is 2 because frequency[2] == 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,2,3,3,3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 1, 2 and 3 are all lucky numbers, return the largest of them.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,2,2,3,3]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There are no lucky numbers in the array.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 500</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 500</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the frequency of each integer in the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Get all lucky numbers and return the largest of them.
-</details>
diff --git a/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array.go b/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array.go
deleted file mode 100644
index 26e83d6dd..000000000
--- a/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem1394
-
-func findLucky(arr []int) int {
-	m := make(map[int]int)
-	for _, v := range arr {
-		m[v]++
-	}
-	ans, max := -1, 0
-	for k, v := range m {
-		if k > max && k == v {
-			ans, max = k, v
-		}
-	}
-	return ans
-}
diff --git a/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array_test.go b/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array_test.go
deleted file mode 100644
index bf75d1b17..000000000
--- a/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem1394
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestFindLucky(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{2, 2, 3, 4},
-			want: 2,
-		},
-		{
-			in:   []int{1, 2, 2, 3, 3, 3},
-			want: 3,
-		},
-		{
-			in:   []int{2, 2, 2, 3, 3},
-			want: -1,
-		},
-		{
-			in:   []int{5},
-			want: -1,
-		},
-		{
-			in:   []int{7, 7, 7, 7, 7, 7, 7},
-			want: 7,
-		},
-	}
-	for _, tt := range tests {
-		got := findLucky(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/find-median-from-data-stream/README.md b/problems/find-median-from-data-stream/README.md
deleted file mode 100644
index 0c980debd..000000000
--- a/problems/find-median-from-data-stream/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flip-game-ii "Flip Game II")
-　　　　　　　　　　　　　　　　
-[Next >](../best-meeting-point "Best Meeting Point")
-
-## [295. Find Median from Data Stream (Hard)](https://leetcode.com/problems/find-median-from-data-stream "数据流的中位数")
-
-<p>The <strong>median</strong> is the middle value in an ordered integer list. If the size of the list is even, there is no middle value and the median is the mean of the two middle values.</p>
-
-<ul>
-	<li>For example, for <code>arr = [2,3,4]</code>, the median is <code>3</code>.</li>
-	<li>For example, for <code>arr = [2,3]</code>, the median is <code>(2 + 3) / 2 = 2.5</code>.</li>
-</ul>
-
-<p>Implement the MedianFinder class:</p>
-
-<ul>
-	<li><code>MedianFinder()</code> initializes the <code>MedianFinder</code> object.</li>
-	<li><code>void addNum(int num)</code> adds the integer <code>num</code> from the data stream to the data structure.</li>
-	<li><code>double findMedian()</code> returns the median of all elements so far. Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MedianFinder&quot;, &quot;addNum&quot;, &quot;addNum&quot;, &quot;findMedian&quot;, &quot;addNum&quot;, &quot;findMedian&quot;]
-[[], [1], [2], [], [3], []]
-<strong>Output</strong>
-[null, null, null, 1.5, null, 2.0]
-
-<strong>Explanation</strong>
-MedianFinder medianFinder = new MedianFinder();
-medianFinder.addNum(1);    // arr = [1]
-medianFinder.addNum(2);    // arr = [1, 2]
-medianFinder.findMedian(); // return 1.5 (i.e., (1 + 2) / 2)
-medianFinder.addNum(3);    // arr[1, 2, 3]
-medianFinder.findMedian(); // return 2.0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-10<sup>5</sup> &lt;= num &lt;= 10<sup>5</sup></code></li>
-	<li>There will be at least one element in the data structure before calling <code>findMedian</code>.</li>
-	<li>At most <code>5 * 10<sup>4</sup></code> calls will be made to <code>addNum</code> and <code>findMedian</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>If all integer numbers from the stream are in the range <code>[0, 100]</code>, how would you optimize your solution?</li>
-	<li>If <code>99%</code> of all integer numbers from the stream are in the range <code>[0, 100]</code>, how would you optimize your solution?</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Similar Questions
-  1. [Sliding Window Median](../sliding-window-median) (Hard)
-  1. [Finding MK Average](../finding-mk-average) (Hard)
diff --git a/problems/find-median-from-data-stream/find_median_from_data_stream.go b/problems/find-median-from-data-stream/find_median_from_data_stream.go
deleted file mode 100644
index 8b568a2dc..000000000
--- a/problems/find-median-from-data-stream/find_median_from_data_stream.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem295
diff --git a/problems/find-median-from-data-stream/find_median_from_data_stream_test.go b/problems/find-median-from-data-stream/find_median_from_data_stream_test.go
deleted file mode 100644
index 8b568a2dc..000000000
--- a/problems/find-median-from-data-stream/find_median_from_data_stream_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem295
diff --git a/problems/find-median-given-frequency-of-numbers/README.md b/problems/find-median-given-frequency-of-numbers/README.md
deleted file mode 100644
index 012bc7fbb..000000000
--- a/problems/find-median-given-frequency-of-numbers/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../managers-with-at-least-5-direct-reports "Managers with at Least 5 Direct Reports")
-　　　　　　　　　　　　　　　　
-[Next >](../subtree-of-another-tree "Subtree of Another Tree")
-
-## [571. Find Median Given Frequency of Numbers (Hard)](https://leetcode.com/problems/find-median-given-frequency-of-numbers "给定数字的频率查询中位数")
-
-<p>The <code>Numbers</code> table keeps the value of number and its frequency.</p>
-
-<pre>
-+----------+-------------+
-|  Number  |  Frequency  |
-+----------+-------------|
-|  0       |  7          |
-|  1       |  1          |
-|  2       |  3          |
-|  3       |  1          |
-+----------+-------------+
-</pre>
-
-<p>In this table, the numbers are <code>0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 2, 3</code>, so the median is <code>(0 + 0) / 2 = 0</code>.</p>
-
-<pre>
-+--------+
-| median |
-+--------|
-| 0.0000 |
-+--------+
-</pre>
-
-<p>Write a query to find the median of all numbers and name the result as <code>median</code>.</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Median Employee Salary](../median-employee-salary) (Hard)
diff --git a/problems/find-median-given-frequency-of-numbers/find_median_given_frequency_of_numbers.sql b/problems/find-median-given-frequency-of-numbers/find_median_given_frequency_of_numbers.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/find-median-given-frequency-of-numbers/find_median_given_frequency_of_numbers.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/find-median-given-frequency-of-numbers/mysql_schemas.sql b/problems/find-median-given-frequency-of-numbers/mysql_schemas.sql
deleted file mode 100644
index 045c651e6..000000000
--- a/problems/find-median-given-frequency-of-numbers/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Numbers (num int, frequency int);
-Truncate table Numbers;
-insert into Numbers (num, frequency) values ('0', '7');
-insert into Numbers (num, frequency) values ('1', '1');
-insert into Numbers (num, frequency) values ('2', '3');
-insert into Numbers (num, frequency) values ('3', '1');
diff --git a/problems/find-minimum-in-rotated-sorted-array-ii/README.md b/problems/find-minimum-in-rotated-sorted-array-ii/README.md
deleted file mode 100644
index 5fa38008e..000000000
--- a/problems/find-minimum-in-rotated-sorted-array-ii/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-minimum-in-rotated-sorted-array "Find Minimum in Rotated Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../min-stack "Min Stack")
-
-## [154. Find Minimum in Rotated Sorted Array II (Hard)](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii "寻找旋转排序数组中的最小值 II")
-
-<p>Suppose an array of length <code>n</code> sorted in ascending order is <strong>rotated</strong> between <code>1</code> and <code>n</code> times. For example, the array <code>nums = [0,1,4,4,5,6,7]</code> might become:</p>
-
-<ul>
-	<li><code>[4,5,6,7,0,1,4]</code> if it was rotated <code>4</code> times.</li>
-	<li><code>[0,1,4,4,5,6,7]</code> if it was rotated <code>7</code> times.</li>
-</ul>
-
-<p>Notice that <strong>rotating</strong> an array <code>[a[0], a[1], a[2], ..., a[n-1]]</code> 1 time results in the array <code>[a[n-1], a[0], a[1], a[2], ..., a[n-2]]</code>.</p>
-
-<p>Given the sorted rotated array <code>nums</code> that may contain <strong>duplicates</strong>, return <em>the minimum element of this array</em>.</p>
-
-<p>You must decrease the overall operation steps as much as possible.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,3,5]
-<strong>Output:</strong> 1
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [2,2,2,0,1]
-<strong>Output:</strong> 0
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 5000</code></li>
-	<li><code>-5000 &lt;= nums[i] &lt;= 5000</code></li>
-	<li><code>nums</code> is sorted and rotated between <code>1</code> and <code>n</code> times.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> This problem is similar to&nbsp;<a href="https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/" target="_blank">Find Minimum in Rotated Sorted Array</a>, but&nbsp;<code>nums</code> may contain <strong>duplicates</strong>. Would this affect the runtime complexity? How and why?</p>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Find Minimum in Rotated Sorted Array](../find-minimum-in-rotated-sorted-array) (Medium)
diff --git a/problems/find-minimum-in-rotated-sorted-array-ii/find_minimum_in_rotated_sorted_array_ii.go b/problems/find-minimum-in-rotated-sorted-array-ii/find_minimum_in_rotated_sorted_array_ii.go
deleted file mode 100644
index 9e0311d0f..000000000
--- a/problems/find-minimum-in-rotated-sorted-array-ii/find_minimum_in_rotated_sorted_array_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem154
diff --git a/problems/find-minimum-in-rotated-sorted-array-ii/find_minimum_in_rotated_sorted_array_ii_test.go b/problems/find-minimum-in-rotated-sorted-array-ii/find_minimum_in_rotated_sorted_array_ii_test.go
deleted file mode 100644
index 9e0311d0f..000000000
--- a/problems/find-minimum-in-rotated-sorted-array-ii/find_minimum_in_rotated_sorted_array_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem154
diff --git a/problems/find-minimum-in-rotated-sorted-array/README.md b/problems/find-minimum-in-rotated-sorted-array/README.md
deleted file mode 100644
index b0b96b8c4..000000000
--- a/problems/find-minimum-in-rotated-sorted-array/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-product-subarray "Maximum Product Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../find-minimum-in-rotated-sorted-array-ii "Find Minimum in Rotated Sorted Array II")
-
-## [153. Find Minimum in Rotated Sorted Array (Medium)](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array "寻找旋转排序数组中的最小值")
-
-<p>Suppose an array of length <code>n</code> sorted in ascending order is <strong>rotated</strong> between <code>1</code> and <code>n</code> times. For example, the array <code>nums = [0,1,2,4,5,6,7]</code> might become:</p>
-
-<ul>
-	<li><code>[4,5,6,7,0,1,2]</code> if it was rotated <code>4</code> times.</li>
-	<li><code>[0,1,2,4,5,6,7]</code> if it was rotated <code>7</code> times.</li>
-</ul>
-
-<p>Notice that <strong>rotating</strong> an array <code>[a[0], a[1], a[2], ..., a[n-1]]</code> 1 time results in the array <code>[a[n-1], a[0], a[1], a[2], ..., a[n-2]]</code>.</p>
-
-<p>Given the sorted rotated array <code>nums</code> of <strong>unique</strong> elements, return <em>the minimum element of this array</em>.</p>
-
-<p>You must write an algorithm that runs in&nbsp;<code>O(log n) time.</code></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,4,5,1,2]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The original array was [1,2,3,4,5] rotated 3 times.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,5,6,7,0,1,2]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The original array was [0,1,2,4,5,6,7] and it was rotated 4 times.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [11,13,15,17]
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> The original array was [11,13,15,17] and it was rotated 4 times. 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 5000</code></li>
-	<li><code>-5000 &lt;= nums[i] &lt;= 5000</code></li>
-	<li>All the integers of <code>nums</code> are <strong>unique</strong>.</li>
-	<li><code>nums</code> is sorted and rotated between <code>1</code> and <code>n</code> times.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Search in Rotated Sorted Array](../search-in-rotated-sorted-array) (Medium)
-  1. [Find Minimum in Rotated Sorted Array II](../find-minimum-in-rotated-sorted-array-ii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Array was originally in ascending order. Now that the array is rotated, there would be a point in the array where there is a small deflection from the increasing sequence. eg. The array would be something like [4, 5, 6, 7, 0, 1, 2].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can divide the search space into two and see which direction to go.
-Can you think of an algorithm which has O(logN) search complexity?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-<ol>
-<li>All the elements to the left of inflection point > first element of the array.</li>
-<li>All the elements to the right of inflection point < first element of the array.</li>
-<ol>
-</details>
diff --git a/problems/find-minimum-in-rotated-sorted-array/find_minimum_in_rotated_sorted_array.go b/problems/find-minimum-in-rotated-sorted-array/find_minimum_in_rotated_sorted_array.go
deleted file mode 100644
index 028b3ae46..000000000
--- a/problems/find-minimum-in-rotated-sorted-array/find_minimum_in_rotated_sorted_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem153
diff --git a/problems/find-minimum-in-rotated-sorted-array/find_minimum_in_rotated_sorted_array_test.go b/problems/find-minimum-in-rotated-sorted-array/find_minimum_in_rotated_sorted_array_test.go
deleted file mode 100644
index 028b3ae46..000000000
--- a/problems/find-minimum-in-rotated-sorted-array/find_minimum_in_rotated_sorted_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem153
diff --git a/problems/find-minimum-time-to-finish-all-jobs/README.md b/problems/find-minimum-time-to-finish-all-jobs/README.md
deleted file mode 100644
index 04d2f0c05..000000000
--- a/problems/find-minimum-time-to-finish-all-jobs/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimize-hamming-distance-after-swap-operations "Minimize Hamming Distance After Swap Operations")
-　　　　　　　　　　　　　　　　
-[Next >](../checking-existence-of-edge-length-limited-paths-ii "Checking Existence of Edge Length Limited Paths II")
-
-## [1723. Find Minimum Time to Finish All Jobs (Hard)](https://leetcode.com/problems/find-minimum-time-to-finish-all-jobs "完成所有工作的最短时间")
-
-<p>You are given an integer array <code>jobs</code>, where <code>jobs[i]</code> is the amount of time it takes to complete the <code>i<sup>th</sup></code> job.</p>
-
-<p>There are <code>k</code> workers that you can assign jobs to. Each job should be assigned to <strong>exactly</strong> one worker. The <strong>working time</strong> of a worker is the sum of the time it takes to complete all jobs assigned to them. Your goal is to devise an optimal assignment such that the <strong>maximum working time</strong> of any worker is <strong>minimized</strong>.</p>
-
-<p><em>Return the <strong>minimum</strong> possible <strong>maximum working time</strong> of any assignment. </em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> jobs = [3,2,3], k = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> By assigning each person one job, the maximum time is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> jobs = [1,2,4,7,8], k = 2
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> Assign the jobs the following way:
-Worker 1: 1, 2, 8 (working time = 1 + 2 + 8 = 11)
-Worker 2: 4, 7 (working time = 4 + 7 = 11)
-The maximum working time is 11.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= jobs.length &lt;= 12</code></li>
-	<li><code>1 &lt;= jobs[i] &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can select a subset of tasks and assign it to a worker then solve the subproblem on the remaining tasks
-</details>
diff --git a/problems/find-missing-observations/README.md b/problems/find-missing-observations/README.md
deleted file mode 100644
index 65ccb1f6d..000000000
--- a/problems/find-missing-observations/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-moves-to-convert-string "Minimum Moves to Convert String")
-　　　　　　　　　　　　　　　　
-[Next >](../stone-game-ix "Stone Game IX")
-
-## [2028. Find Missing Observations (Medium)](https://leetcode.com/problems/find-missing-observations "找出缺失的观测数据")
-
-<p>You have observations of <code>n + m</code> <strong>6-sided</strong> dice rolls with each face numbered from <code>1</code> to <code>6</code>. <code>n</code> of the observations went missing, and you only have the observations of <code>m</code> rolls. Fortunately, you have also calculated the <strong>average value</strong> of the <code>n + m</code> rolls.</p>
-
-<p>You are given an integer array <code>rolls</code> of length <code>m</code> where <code>rolls[i]</code> is the value of the <code>i<sup>th</sup></code> observation. You are also given the two integers <code>mean</code> and <code>n</code>.</p>
-
-<p>Return <em>an array of length </em><code>n</code><em> containing the missing observations such that the <strong>average value </strong>of the </em><code>n + m</code><em> rolls is <strong>exactly</strong> </em><code>mean</code>. If there are multiple valid answers, return <em>any of them</em>. If no such array exists, return <em>an empty array</em>.</p>
-
-<p>The <strong>average value</strong> of a set of <code>k</code> numbers is the sum of the numbers divided by <code>k</code>.</p>
-
-<p>Note that <code>mean</code> is an integer, so the sum of the <code>n + m</code> rolls should be divisible by <code>n + m</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rolls = [3,2,4,3], mean = 4, n = 2
-<strong>Output:</strong> [6,6]
-<strong>Explanation:</strong> The mean of all n + m rolls is (3 + 2 + 4 + 3 + 6 + 6) / 6 = 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rolls = [1,5,6], mean = 3, n = 4
-<strong>Output:</strong> [2,3,2,2]
-<strong>Explanation:</strong> The mean of all n + m rolls is (1 + 5 + 6 + 2 + 3 + 2 + 2) / 7 = 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> rolls = [1,2,3,4], mean = 6, n = 4
-<strong>Output:</strong> []
-<strong>Explanation:</strong> It is impossible for the mean to be 6 no matter what the 4 missing rolls are.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == rolls.length</code></li>
-	<li><code>1 &lt;= n, m &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= rolls[i], mean &lt;= 6</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What should the sum of the n rolls be?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Could you generate an array of size n such that each element is between 1 and 6?
-</details>
diff --git a/problems/find-mode-in-binary-search-tree/README.md b/problems/find-mode-in-binary-search-tree/README.md
deleted file mode 100644
index 854f06464..000000000
--- a/problems/find-mode-in-binary-search-tree/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../keyboard-row "Keyboard Row")
-　　　　　　　　　　　　　　　　
-[Next >](../ipo "IPO")
-
-## [501. Find Mode in Binary Search Tree (Easy)](https://leetcode.com/problems/find-mode-in-binary-search-tree "二叉搜索树中的众数")
-
-<p>Given the <code>root</code> of a binary search tree (BST) with duplicates, return <em>all the <a href="https://en.wikipedia.org/wiki/Mode_(statistics)" target="_blank">mode(s)</a> (i.e., the most frequently occurred element) in it</em>.</p>
-
-<p>If the tree has more than one mode, return them in <strong>any order</strong>.</p>
-
-<p>Assume a BST is defined as follows:</p>
-
-<ul>
-	<li>The left subtree of a node contains only nodes with keys <strong>less than or equal to</strong> the node&#39;s key.</li>
-	<li>The right subtree of a node contains only nodes with keys <strong>greater than or equal to</strong> the node&#39;s key.</li>
-	<li>Both the left and right subtrees must also be binary search trees.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/11/mode-tree.jpg" style="width: 142px; height: 222px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2,2]
-<strong>Output:</strong> [2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [0]
-<strong>Output:</strong> [0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you do that without using any extra space? (Assume that the implicit stack space incurred due to recursion does not count).
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Validate Binary Search Tree](../validate-binary-search-tree) (Medium)
diff --git a/problems/find-mode-in-binary-search-tree/find_mode_in_binary_search_tree.go b/problems/find-mode-in-binary-search-tree/find_mode_in_binary_search_tree.go
deleted file mode 100644
index d43c7d962..000000000
--- a/problems/find-mode-in-binary-search-tree/find_mode_in_binary_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem501
diff --git a/problems/find-mode-in-binary-search-tree/find_mode_in_binary_search_tree_test.go b/problems/find-mode-in-binary-search-tree/find_mode_in_binary_search_tree_test.go
deleted file mode 100644
index d43c7d962..000000000
--- a/problems/find-mode-in-binary-search-tree/find_mode_in_binary_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem501
diff --git a/problems/find-n-unique-integers-sum-up-to-zero/README.md b/problems/find-n-unique-integers-sum-up-to-zero/README.md
deleted file mode 100644
index adcf4c9f1..000000000
--- a/problems/find-n-unique-integers-sum-up-to-zero/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-team-size "Find the Team Size")
-　　　　　　　　　　　　　　　　
-[Next >](../all-elements-in-two-binary-search-trees "All Elements in Two Binary Search Trees")
-
-## [1304. Find N Unique Integers Sum up to Zero (Easy)](https://leetcode.com/problems/find-n-unique-integers-sum-up-to-zero "和为零的N个唯一整数")
-
-<p>Given an integer <code>n</code>, return <strong>any</strong> array containing <code>n</code> <strong>unique</strong> integers such that they add up to <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> [-7,-1,1,3,4]
-<strong>Explanation:</strong> These arrays also are accepted [-5,-1,1,2,3] , [-3,-1,2,-2,4].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> [-1,0,1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> [0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Return an array where the values are symmetric. (+x , -x).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If n is odd, append value 0 in your returned array.
-</details>
diff --git a/problems/find-nearest-point-that-has-the-same-x-or-y-coordinate/README.md b/problems/find-nearest-point-that-has-the-same-x-or-y-coordinate/README.md
deleted file mode 100644
index f390364e6..000000000
--- a/problems/find-nearest-point-that-has-the-same-x-or-y-coordinate/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-path-in-a-hidden-grid "Shortest Path in a Hidden Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-number-is-a-sum-of-powers-of-three "Check if Number is a Sum of Powers of Three")
-
-## [1779. Find Nearest Point That Has the Same X or Y Coordinate (Easy)](https://leetcode.com/problems/find-nearest-point-that-has-the-same-x-or-y-coordinate "找到最近的有相同 X 或 Y 坐标的点")
-
-<p>You are given two integers, <code>x</code> and <code>y</code>, which represent your current location on a Cartesian grid: <code>(x, y)</code>. You are also given an array <code>points</code> where each <code>points[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> represents that a point exists at <code>(a<sub>i</sub>, b<sub>i</sub>)</code>. A point is <strong>valid</strong> if it shares the same x-coordinate or the same y-coordinate as your location.</p>
-
-<p>Return <em>the index <strong>(0-indexed)</strong> of the <strong>valid</strong> point with the smallest <strong>Manhattan distance</strong> from your current location</em>. If there are multiple, return <em>the valid point with the <strong>smallest</strong> index</em>. If there are no valid points, return <code>-1</code>.</p>
-
-<p>The <strong>Manhattan distance</strong> between two points <code>(x<sub>1</sub>, y<sub>1</sub>)</code> and <code>(x<sub>2</sub>, y<sub>2</sub>)</code> is <code>abs(x<sub>1</sub> - x<sub>2</sub>) + abs(y<sub>1</sub> - y<sub>2</sub>)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 3, y = 4, points = [[1,2],[3,1],[2,4],[2,3],[4,4]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Of all the points, only [3,1], [2,4] and [4,4] are valid. Of the valid points, [2,4] and [4,4] have the smallest Manhattan distance from your current location, with a distance of 1. [2,4] has the smallest index, so return 2.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 3, y = 4, points = [[3,4]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The answer is allowed to be on the same location as your current location.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 3, y = 4, points = [[2,3]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There are no valid points.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= points.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>1 &lt;= x, y, a<sub>i</sub>, b<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [K Closest Points to Origin](../k-closest-points-to-origin) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate through each point, and keep track of the current point with the smallest Manhattan distance from your current location.
-</details>
diff --git a/problems/find-nearest-right-node-in-binary-tree/README.md b/problems/find-nearest-right-node-in-binary-tree/README.md
deleted file mode 100644
index 3202654d0..000000000
--- a/problems/find-nearest-right-node-in-binary-tree/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-achievable-transfer-requests "Maximum Number of Achievable Transfer Requests")
-　　　　　　　　　　　　　　　　
-[Next >](../design-parking-system "Design Parking System")
-
-## [1602. Find Nearest Right Node in Binary Tree (Medium)](https://leetcode.com/problems/find-nearest-right-node-in-binary-tree "找到二叉树中最近的右侧节点")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use BFS, traverse the tree level by level and always push the left node first
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When you reach the target node, mark  a boolean variable true
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If you meet another node in the same level after marking the boolean true, return this node.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-If you did not meet new nodes in the same level and started traversing a new level, return Null
-</details>
diff --git a/problems/find-numbers-with-even-number-of-digits/README.md b/problems/find-numbers-with-even-number-of-digits/README.md
deleted file mode 100644
index 22abd4751..000000000
--- a/problems/find-numbers-with-even-number-of-digits/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../weather-type-in-each-country "Weather Type in Each Country")
-　　　　　　　　　　　　　　　　
-[Next >](../divide-array-in-sets-of-k-consecutive-numbers "Divide Array in Sets of K Consecutive Numbers")
-
-## [1295. Find Numbers with Even Number of Digits (Easy)](https://leetcode.com/problems/find-numbers-with-even-number-of-digits "统计位数为偶数的数字")
-
-<p>Given an array <code>nums</code> of integers, return how many of them contain an <strong>even number</strong> of digits.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [12,345,2,6,7896]
-<strong>Output:</strong> 2
-<strong>Explanation: 
-</strong>12 contains 2 digits (even number of digits).&nbsp;
-345 contains 3 digits (odd number of digits).&nbsp;
-2 contains 1 digit (odd number of digits).&nbsp;
-6 contains 1 digit (odd number of digits).&nbsp;
-7896 contains 4 digits (even number of digits).&nbsp;
-Therefore only 12 and 7896 contain an even number of digits.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [555,901,482,1771]
-<strong>Output:</strong> 1 
-<strong>Explanation: </strong>
-Only 1771 contains an even number of digits.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 500</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Finding 3-Digit Even Numbers](../finding-3-digit-even-numbers) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to compute the number of digits of a number ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Divide the number by 10 again and again to get the number of digits.
-</details>
diff --git a/problems/find-original-array-from-doubled-array/README.md b/problems/find-original-array-from-doubled-array/README.md
deleted file mode 100644
index 82ef650df..000000000
--- a/problems/find-original-array-from-doubled-array/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-number-of-pairs-with-absolute-difference-k "Count Number of Pairs With Absolute Difference K")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-earnings-from-taxi "Maximum Earnings From Taxi")
-
-## [2007. Find Original Array From Doubled Array (Medium)](https://leetcode.com/problems/find-original-array-from-doubled-array "从双倍数组中还原原数组")
-
-<p>An integer array <code>original</code> is transformed into a <strong>doubled</strong> array <code>changed</code> by appending <strong>twice the value</strong> of every element in <code>original</code>, and then randomly <strong>shuffling</strong> the resulting array.</p>
-
-<p>Given an array <code>changed</code>, return <code>original</code><em> if </em><code>changed</code><em> is a <strong>doubled</strong> array. If </em><code>changed</code><em> is not a <strong>doubled</strong> array, return an empty array. The elements in</em> <code>original</code> <em>may be returned in <strong>any</strong> order</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> changed = [1,3,4,2,6,8]
-<strong>Output:</strong> [1,3,4]
-<strong>Explanation:</strong> One possible original array could be [1,3,4]:
-- Twice the value of 1 is 1 * 2 = 2.
-- Twice the value of 3 is 3 * 2 = 6.
-- Twice the value of 4 is 4 * 2 = 8.
-Other original arrays could be [4,3,1] or [3,1,4].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> changed = [6,3,0,1]
-<strong>Output:</strong> []
-<strong>Explanation:</strong> changed is not a doubled array.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> changed = [1]
-<strong>Output:</strong> []
-<strong>Explanation:</strong> changed is not a doubled array.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= changed.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= changed[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If changed is a doubled array, you should be able to delete elements and their doubled values until the array is empty.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Which element is guaranteed to not be a doubled value? It is the smallest element.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-After removing the smallest element and its double from changed, is there another number that is guaranteed to not be a doubled value?
-</details>
diff --git a/problems/find-peak-element/README.md b/problems/find-peak-element/README.md
deleted file mode 100644
index 88656e492..000000000
--- a/problems/find-peak-element/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../one-edit-distance "One Edit Distance")
-　　　　　　　　　　　　　　　　
-[Next >](../missing-ranges "Missing Ranges")
-
-## [162. Find Peak Element (Medium)](https://leetcode.com/problems/find-peak-element "寻找峰值")
-
-<p>A peak element is an element that is strictly greater than its neighbors.</p>
-
-<p>Given an integer array <code>nums</code>, find a peak element, and return its index. If&nbsp;the array contains multiple peaks, return the index to <strong>any of the peaks</strong>.</p>
-
-<p>You may imagine that <code>nums[-1] = nums[n] = -&infin;</code>.</p>
-
-<p>You must write an algorithm that runs in&nbsp;<code>O(log n)</code> time.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 3 is a peak element and your function should return the index number 2.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1,3,5,6,4]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Your function can return either index number 1 where the peak element is 2, or index number 5 where the peak element is 6.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>nums[i] != nums[i + 1]</code> for all valid <code>i</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Peak Index in a Mountain Array](../peak-index-in-a-mountain-array) (Easy)
-  1. [Find a Peak Element II](../find-a-peak-element-ii) (Medium)
diff --git a/problems/find-peak-element/find_peak_element.go b/problems/find-peak-element/find_peak_element.go
deleted file mode 100644
index befa4441c..000000000
--- a/problems/find-peak-element/find_peak_element.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem162
diff --git a/problems/find-peak-element/find_peak_element_test.go b/problems/find-peak-element/find_peak_element_test.go
deleted file mode 100644
index befa4441c..000000000
--- a/problems/find-peak-element/find_peak_element_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem162
diff --git a/problems/find-permutation/README.md b/problems/find-permutation/README.md
deleted file mode 100644
index b0a0b5770..000000000
--- a/problems/find-permutation/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-good-base "Smallest Good Base")
-　　　　　　　　　　　　　　　　
-[Next >](../max-consecutive-ones "Max Consecutive Ones")
-
-## [484. Find Permutation (Medium)](https://leetcode.com/problems/find-permutation "寻找排列")
-
-<p>
-By now, you are given a <b>secret signature</b> consisting of character 'D' and 'I'. 'D' represents a decreasing relationship between two numbers, 'I' represents an increasing relationship between two numbers. And our <b>secret signature</b> was constructed by a special integer array, which contains uniquely all the different number from 1 to n (n is the length of the secret signature plus 1). For example, the secret signature "DI" can be constructed by array [2,1,3] or [3,1,2], but won't be constructed by array [3,2,4] or [2,1,3,4], which are both illegal constructing special string that can't represent the "DI" <b>secret signature</b>.
-</p>
-
-<p>
-On the other hand, now your job is to find the lexicographically smallest permutation of [1, 2, ... n] could refer to the given <b>secret signature</b> in the input.
-</p>
-
-<p><b>Example 1:</b><br />
-<pre><b>Input:</b> "I"
-<b>Output:</b> [1,2]
-<b>Explanation:</b> [1,2] is the only legal initial spectial string can construct secret signature "I", where the number 1 and 2 construct an increasing relationship.
-</pre>
-</p>
-
-<p><b>Example 2:</b><br />
-<pre><b>Input:</b> "DI"
-<b>Output:</b> [2,1,3]
-<b>Explanation:</b> Both [2,1,3] and [3,1,2] can construct the secret signature "DI", </br>but since we want to find the one with the smallest lexicographical permutation, you need to output [2,1,3]
-</pre>
-</p>
-
-<p><b>Note:</b>
-<li>The input string will only contain the character 'D' and 'I'.</li>
-<li>The length of input string is a positive integer and will not exceed 10,000</li>
-</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
diff --git a/problems/find-permutation/find_permutation.go b/problems/find-permutation/find_permutation.go
deleted file mode 100644
index 97ddb520b..000000000
--- a/problems/find-permutation/find_permutation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem484
diff --git a/problems/find-permutation/find_permutation_test.go b/problems/find-permutation/find_permutation_test.go
deleted file mode 100644
index 97ddb520b..000000000
--- a/problems/find-permutation/find_permutation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem484
diff --git a/problems/find-pivot-index/README.md b/problems/find-pivot-index/README.md
deleted file mode 100644
index 25296cf14..000000000
--- a/problems/find-pivot-index/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../candy-crush "Candy Crush")
-　　　　　　　　　　　　　　　　
-[Next >](../split-linked-list-in-parts "Split Linked List in Parts")
-
-## [724. Find Pivot Index (Easy)](https://leetcode.com/problems/find-pivot-index "寻找数组的中心下标")
-
-<p>Given an array of integers <code>nums</code>, calculate the <strong>pivot index</strong> of this array.</p>
-
-<p>The <strong>pivot index</strong> is the index where the sum of all the numbers <strong>strictly</strong> to the left of the index is equal to the sum of all the numbers <strong>strictly</strong> to the index&#39;s right.</p>
-
-<p>If the index is on the left edge of the array, then the left sum is <code>0</code> because there are no elements to the left. This also applies to the right edge of the array.</p>
-
-<p>Return <em>the <strong>leftmost pivot index</strong></em>. If no such index exists, return -1.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,7,3,6,5,6]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-The pivot index is 3.
-Left sum = nums[0] + nums[1] + nums[2] = 1 + 7 + 3 = 11
-Right sum = nums[4] + nums[5] = 5 + 6 = 11
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>
-There is no index that satisfies the conditions in the problem statement.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,-1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-The pivot index is 0.
-Left sum = 0 (no elements to the left of index 0)
-Right sum = nums[1] + nums[2] = 1 + -1 = 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-1000 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Subarray Sum Equals K](../subarray-sum-equals-k) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can precompute prefix sums P[i] = nums[0] + nums[1] + ... + nums[i-1].
-Then for each index, the left sum is P[i], and the right sum is P[P.length - 1] - P[i] - nums[i].
-</details>
diff --git a/problems/find-pivot-index/find_pivot_index.go b/problems/find-pivot-index/find_pivot_index.go
deleted file mode 100644
index 7e72cc4de..000000000
--- a/problems/find-pivot-index/find_pivot_index.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem724
-
-func pivotIndex(nums []int) int {
-	left, right := 0, 0
-	for _, v := range nums {
-		right += v
-	}
-	for i, v := range nums {
-		if right -= v; left == right {
-			return i
-		}
-		left += v
-	}
-	return -1
-}
diff --git a/problems/find-pivot-index/find_pivot_index_test.go b/problems/find-pivot-index/find_pivot_index_test.go
deleted file mode 100644
index e1d79c6e5..000000000
--- a/problems/find-pivot-index/find_pivot_index_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem724
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestPivotIndex(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 7, 3, 6, 5, 6},
-			want: 3,
-		},
-		{
-			in:   []int{1, 2, 3},
-			want: -1,
-		},
-		{
-			in:   []int{0},
-			want: 0,
-		},
-		{
-			in:   []int{0, 0},
-			want: 0,
-		},
-		{
-			in:   []int{1, 2, 1},
-			want: 1,
-		},
-		{
-			in:   []int{},
-			want: -1,
-		},
-	}
-	for _, tt := range tests {
-		got := pivotIndex(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/find-positive-integer-solution-for-a-given-equation/README.md b/problems/find-positive-integer-solution-for-a-given-equation/README.md
deleted file mode 100644
index 51ee21ffb..000000000
--- a/problems/find-positive-integer-solution-for-a-given-equation/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../web-crawler "Web Crawler")
-　　　　　　　　　　　　　　　　
-[Next >](../circular-permutation-in-binary-representation "Circular Permutation in Binary Representation")
-
-## [1237. Find Positive Integer Solution for a Given Equation (Medium)](https://leetcode.com/problems/find-positive-integer-solution-for-a-given-equation "找出给定方程的正整数解")
-
-<p>Given a callable function <code>f(x, y)</code> <strong>with a hidden formula</strong> and a value <code>z</code>, reverse engineer the formula and return <em>all positive integer pairs </em><code>x</code><em> and </em><code>y</code><em> where </em><code>f(x,y) == z</code>. You may return the pairs in any order.</p>
-
-<p>While the exact formula is hidden, the function is monotonically increasing, i.e.:</p>
-
-<ul>
-	<li><code>f(x, y) &lt; f(x + 1, y)</code></li>
-	<li><code>f(x, y) &lt; f(x, y + 1)</code></li>
-</ul>
-
-<p>The function interface is defined like this:</p>
-
-<pre>
-interface CustomFunction {
-public:
-  // Returns some positive integer f(x, y) for two positive integers x and y based on a formula.
-  int f(int x, int y);
-};
-</pre>
-
-<p>We will judge your solution as follows:</p>
-
-<ul>
-	<li>The judge has a list of <code>9</code> hidden implementations of <code>CustomFunction</code>, along with a way to generate an <strong>answer key</strong> of all valid pairs for a specific <code>z</code>.</li>
-	<li>The judge will receive two inputs: a <code>function_id</code> (to determine which implementation to test your code with), and the target <code>z</code>.</li>
-	<li>The judge will call your <code>findSolution</code> and compare your results with the <strong>answer key</strong>.</li>
-	<li>If your results match the <strong>answer key</strong>, your solution will be <code>Accepted</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> function_id = 1, z = 5
-<strong>Output:</strong> [[1,4],[2,3],[3,2],[4,1]]
-<strong>Explanation:</strong> The hidden formula for function_id = 1 is f(x, y) = x + y.
-The following positive integer values of x and y make f(x, y) equal to 5:
-x=1, y=4 -&gt; f(1, 4) = 1 + 4 = 5.
-x=2, y=3 -&gt; f(2, 3) = 2 + 3 = 5.
-x=3, y=2 -&gt; f(3, 2) = 3 + 2 = 5.
-x=4, y=1 -&gt; f(4, 1) = 4 + 1 = 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> function_id = 2, z = 5
-<strong>Output:</strong> [[1,5],[5,1]]
-<strong>Explanation:</strong> The hidden formula for function_id = 2 is f(x, y) = x * y.
-The following positive integer values of x and y make f(x, y) equal to 5:
-x=1, y=5 -&gt; f(1, 5) = 1 * 5 = 5.
-x=5, y=1 -&gt; f(5, 1) = 5 * 1 = 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= function_id &lt;= 9</code></li>
-	<li><code>1 &lt;= z &lt;= 100</code></li>
-	<li>It is guaranteed that the solutions of <code>f(x, y) == z</code> will be in the range <code>1 &lt;= x, y &lt;= 1000</code>.</li>
-	<li>It is also guaranteed that <code>f(x, y)</code> will fit in 32 bit signed integer if <code>1 &lt;= x, y &lt;= 1000</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Loop over 1 ≤ x,y ≤ 1000 and check if f(x,y) == z.
-</details>
diff --git a/problems/find-right-interval/README.md b/problems/find-right-interval/README.md
deleted file mode 100644
index 629b32340..000000000
--- a/problems/find-right-interval/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../non-overlapping-intervals "Non-overlapping Intervals")
-　　　　　　　　　　　　　　　　
-[Next >](../path-sum-iii "Path Sum III")
-
-## [436. Find Right Interval (Medium)](https://leetcode.com/problems/find-right-interval "寻找右区间")
-
-<p>You are given an array of&nbsp;<code>intervals</code>, where <code>intervals[i] = [start<sub>i</sub>, end<sub>i</sub>]</code>&nbsp;and each <code>start<sub>i</sub></code>&nbsp;is <strong>unique</strong>.</p>
-
-<p>The <strong>r</strong><strong>ight</strong><strong>&nbsp;interval</strong>&nbsp;for an interval <code>i</code> is an interval&nbsp;<code>j</code>&nbsp;such that <code>start<sub>j</sub></code><code>&nbsp;&gt;= end<sub>i</sub></code>&nbsp;and&nbsp;<code>start<sub>j</sub></code>&nbsp;is&nbsp;<strong>minimized</strong>.</p>
-
-<p>Return&nbsp;<em>an array of&nbsp;<strong>right interval</strong>&nbsp;indices for each interval&nbsp;<code>i</code></em>. If no&nbsp;<strong>right interval</strong>&nbsp;exists for interval&nbsp;<code>i</code>, then put&nbsp;<code>-1</code>&nbsp;at index <code>i</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,2]]
-<strong>Output:</strong> [-1]
-<strong>Explanation:</strong> There is only one interval in the collection, so it outputs -1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[3,4],[2,3],[1,2]]
-<strong>Output:</strong> [-1,0,1]
-<strong>Explanation:</strong> There is no right interval for [3,4].
-The right interval for [2,3] is [3,4] since start<sub>0</sub>&nbsp;= 3 is the smallest start that is &gt;= end<sub>1</sub>&nbsp;= 3.
-The right interval for [1,2] is [2,3] since start<sub>1</sub>&nbsp;= 2 is the smallest start that is &gt;= end<sub>2</sub>&nbsp;= 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,4],[2,3],[3,4]]
-<strong>Output:</strong> [-1,2,-1]
-<strong>Explanation:</strong> There is no right interval for [1,4] and [3,4].
-The right interval for [2,3] is [3,4] since start<sub>2</sub> = 3 is the smallest start that is &gt;= end<sub>1</sub>&nbsp;= 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;intervals.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>intervals[i].length == 2</code></li>
-	<li><code>-10<sup>6</sup> &lt;= start<sub>i</sub> &lt;= end<sub>i</sub> &lt;= 10<sup>6</sup></code></li>
-	<li>The start point&nbsp;of each interval is <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Data Stream as Disjoint Intervals](../data-stream-as-disjoint-intervals) (Hard)
diff --git a/problems/find-right-interval/find_right_interval.go b/problems/find-right-interval/find_right_interval.go
deleted file mode 100644
index 7a31fc39c..000000000
--- a/problems/find-right-interval/find_right_interval.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem436
diff --git a/problems/find-right-interval/find_right_interval_test.go b/problems/find-right-interval/find_right_interval_test.go
deleted file mode 100644
index 7a31fc39c..000000000
--- a/problems/find-right-interval/find_right_interval_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem436
diff --git a/problems/find-root-of-n-ary-tree/README.md b/problems/find-root-of-n-ary-tree/README.md
deleted file mode 100644
index 1e76d79f4..000000000
--- a/problems/find-root-of-n-ary-tree/README.md
+++ /dev/null
@@ -1,26 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits "Minimum Possible Integer After at Most K Adjacent Swaps On Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../reformat-date "Reformat Date")
-
-## [1506. Find Root of N-Ary Tree (Medium)](https://leetcode.com/problems/find-root-of-n-ary-tree "找到 N 叉树的根节点")
-
-
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Node with indegree 0 is the root
-</details>
diff --git a/problems/find-servers-that-handled-most-number-of-requests/README.md b/problems/find-servers-that-handled-most-number-of-requests/README.md
deleted file mode 100644
index ac8510ccd..000000000
--- a/problems/find-servers-that-handled-most-number-of-requests/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-valid-matrix-given-row-and-column-sums "Find Valid Matrix Given Row and Column Sums")
-　　　　　　　　　　　　　　　　
-[Next >](../sellers-with-no-sales "Sellers With No Sales")
-
-## [1606. Find Servers That Handled Most Number of Requests (Hard)](https://leetcode.com/problems/find-servers-that-handled-most-number-of-requests "找到处理最多请求的服务器")
-
-<p>You have <code>k</code> servers numbered from <code>0</code> to <code>k-1</code> that are being used to handle multiple requests simultaneously. Each server has infinite computational capacity but <strong>cannot handle more than one request at a time</strong>. The requests are assigned to servers according to a specific algorithm:</p>
-
-<ul>
-	<li>The <code>i<sup>th</sup></code> (0-indexed) request arrives.</li>
-	<li>If all servers are busy, the request is dropped (not handled at all).</li>
-	<li>If the <code>(i % k)<sup>th</sup></code> server is available, assign the request to that server.</li>
-	<li>Otherwise, assign the request to the next available server (wrapping around the list of servers and starting from 0 if necessary). For example, if the <code>i<sup>th</sup></code> server is busy, try to assign the request to the <code>(i+1)<sup>th</sup></code> server, then the <code>(i+2)<sup>th</sup></code> server, and so on.</li>
-</ul>
-
-<p>You are given a <strong>strictly increasing</strong> array <code>arrival</code> of positive integers, where <code>arrival[i]</code> represents the arrival time of the <code>i<sup>th</sup></code> request, and another array <code>load</code>, where <code>load[i]</code> represents the load of the <code>i<sup>th</sup></code> request (the time it takes to complete). Your goal is to find the <strong>busiest server(s)</strong>. A server is considered <strong>busiest</strong> if it handled the most number of requests successfully among all the servers.</p>
-
-<p>Return <em>a list containing the IDs (0-indexed) of the <strong>busiest server(s)</strong></em>. You may return the IDs in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/08/load-1.png" style="width: 389px; height: 221px;" />
-<pre>
-<strong>Input:</strong> k = 3, arrival = [1,2,3,4,5], load = [5,2,3,3,3] 
-<strong>Output:</strong> [1] 
-<strong>Explanation:</strong> 
-All of the servers start out available.
-The first 3 requests are handled by the first 3 servers in order.
-Request 3 comes in. Server 0 is busy, so it&#39;s assigned to the next available server, which is 1.
-Request 4 comes in. It cannot be handled since all servers are busy, so it is dropped.
-Servers 0 and 2 handled one request each, while server 1 handled two requests. Hence server 1 is the busiest server.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3, arrival = [1,2,3,4], load = [1,2,1,2]
-<strong>Output:</strong> [0]
-<strong>Explanation:</strong> 
-The first 3 requests are handled by first 3 servers.
-Request 3 comes in. It is handled by server 0 since the server is available.
-Server 0 handled two requests, while servers 1 and 2 handled one request each. Hence server 0 is the busiest server.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3, arrival = [1,2,3], load = [10,12,11]
-<strong>Output:</strong> [0,1,2]
-<strong>Explanation:</strong> Each server handles a single request, so they are all considered the busiest.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arrival.length, load.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>arrival.length == load.length</code></li>
-	<li><code>1 &lt;= arrival[i], load[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>arrival</code> is <strong>strictly increasing</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-To speed up the next available server search, keep track of the available servers in a sorted structure such as an ordered set.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To determine if a server is available, keep track of the end times for each task in a heap and add the server to the available set once the soonest task ending time is less than or equal to the next task to add.
-</details>
diff --git a/problems/find-smallest-common-element-in-all-rows/README.md b/problems/find-smallest-common-element-in-all-rows/README.md
deleted file mode 100644
index e59271161..000000000
--- a/problems/find-smallest-common-element-in-all-rows/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-knight-moves "Minimum Knight Moves")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-time-to-build-blocks "Minimum Time to Build Blocks")
-
-## [1198. Find Smallest Common Element in All Rows (Medium)](https://leetcode.com/problems/find-smallest-common-element-in-all-rows "找出所有行中最小公共元素")
-
-<p>Given a matrix <code>mat</code>&nbsp;where every row is sorted in <strong>increasing</strong> order, return&nbsp;the <strong>smallest common element</strong> in all rows.</p>
-
-<p>If there is no common element, return&nbsp;<code>-1</code>.</p>
-
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> mat = [[1,2,3,4,5],[2,4,5,8,10],[3,5,7,9,11],[1,3,5,7,9]]
-<strong>Output:</strong> 5
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= mat.length, mat[i].length &lt;= 500</code></li>
-	<li><code>1 &lt;= mat[i][j] &lt;= 10^4</code></li>
-	<li><code>mat[i]</code> is sorted in increasing order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Notice that each row has no duplicates.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is counting the frequency of elements enough to find the answer?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use a data structure to count the frequency of elements.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Find an element whose frequency equals the number of rows.
-</details>
diff --git a/problems/find-smallest-letter-greater-than-target/README.md b/problems/find-smallest-letter-greater-than-target/README.md
deleted file mode 100644
index 49127e3fe..000000000
--- a/problems/find-smallest-letter-greater-than-target/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../network-delay-time "Network Delay Time")
-　　　　　　　　　　　　　　　　
-[Next >](../prefix-and-suffix-search "Prefix and Suffix Search")
-
-## [744. Find Smallest Letter Greater Than Target (Easy)](https://leetcode.com/problems/find-smallest-letter-greater-than-target "寻找比目标字母大的最小字母")
-
-<p>Given a characters array <code>letters</code> that is sorted in <strong>non-decreasing</strong> order and a character <code>target</code>, return <em>the smallest character in the array that is larger than </em><code>target</code>.</p>
-
-<p><strong>Note</strong> that the letters wrap around.</p>
-
-<ul>
-	<li>For example, if <code>target == &#39;z&#39;</code> and <code>letters == [&#39;a&#39;, &#39;b&#39;]</code>, the answer is <code>&#39;a&#39;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> letters = [&quot;c&quot;,&quot;f&quot;,&quot;j&quot;], target = &quot;a&quot;
-<strong>Output:</strong> &quot;c&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> letters = [&quot;c&quot;,&quot;f&quot;,&quot;j&quot;], target = &quot;c&quot;
-<strong>Output:</strong> &quot;f&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> letters = [&quot;c&quot;,&quot;f&quot;,&quot;j&quot;], target = &quot;d&quot;
-<strong>Output:</strong> &quot;f&quot;
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> letters = [&quot;c&quot;,&quot;f&quot;,&quot;j&quot;], target = &quot;g&quot;
-<strong>Output:</strong> &quot;j&quot;
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> letters = [&quot;c&quot;,&quot;f&quot;,&quot;j&quot;], target = &quot;j&quot;
-<strong>Output:</strong> &quot;c&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= letters.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>letters[i]</code> is a lowercase English letter.</li>
-	<li><code>letters</code> is sorted in <strong>non-decreasing</strong> order.</li>
-	<li><code>letters</code> contains at least two different characters.</li>
-	<li><code>target</code> is a lowercase English letter.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to find whether each of 26 next letters are in the given string array.
-</details>
diff --git a/problems/find-smallest-letter-greater-than-target/find_smallest_letter_greater_than_target.go b/problems/find-smallest-letter-greater-than-target/find_smallest_letter_greater_than_target.go
deleted file mode 100644
index 22d1ed62d..000000000
--- a/problems/find-smallest-letter-greater-than-target/find_smallest_letter_greater_than_target.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem744
-
-func nextGreatestLetter(letters []byte, target byte) byte {
-	for _, v := range letters {
-		if v > target {
-			return v
-		}
-	}
-	return letters[0]
-}
diff --git a/problems/find-smallest-letter-greater-than-target/find_smallest_letter_greater_than_target_test.go b/problems/find-smallest-letter-greater-than-target/find_smallest_letter_greater_than_target_test.go
deleted file mode 100644
index aa9ca5644..000000000
--- a/problems/find-smallest-letter-greater-than-target/find_smallest_letter_greater_than_target_test.go
+++ /dev/null
@@ -1,50 +0,0 @@
-package problem744
-
-import "testing"
-
-type testType struct {
-	in     []byte
-	target byte
-	want   byte
-}
-
-func TestNextGreatestLetter(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:     []byte{'c', 'f', 'j'},
-			target: 'a',
-			want:   'c',
-		},
-		{
-			in:     []byte{'c', 'f', 'j'},
-			target: 'c',
-			want:   'f',
-		},
-		{
-			in:     []byte{'c', 'f', 'j'},
-			target: 'd',
-			want:   'f',
-		},
-		{
-			in:     []byte{'c', 'f', 'j'},
-			target: 'g',
-			want:   'j',
-		},
-		{
-			in:     []byte{'c', 'f', 'j'},
-			target: 'j',
-			want:   'c',
-		},
-		{
-			in:     []byte{'c', 'f', 'j'},
-			target: 'k',
-			want:   'c',
-		},
-	}
-	for _, tt := range tests {
-		got := nextGreatestLetter(tt.in, tt.target)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/find-subsequence-of-length-k-with-the-largest-sum/README.md b/problems/find-subsequence-of-length-k-with-the-largest-sum/README.md
deleted file mode 100644
index dcdab30b2..000000000
--- a/problems/find-subsequence-of-length-k-with-the-largest-sum/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subsequence-of-size-k-with-the-largest-even-sum "Subsequence of Size K With the Largest Even Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../find-good-days-to-rob-the-bank "Find Good Days to Rob the Bank")
-
-## [2099. Find Subsequence of Length K With the Largest Sum (Easy)](https://leetcode.com/problems/find-subsequence-of-length-k-with-the-largest-sum "找到和最大的长度为 K 的子序列")
-
-<p>You are given an integer array <code>nums</code> and an integer <code>k</code>. You want to find a <strong>subsequence </strong>of <code>nums</code> of length <code>k</code> that has the <strong>largest</strong> sum.</p>
-
-<p>Return<em> </em><em><strong>any</strong> such subsequence as an integer array of length </em><code>k</code>.</p>
-
-<p>A <strong>subsequence</strong> is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,3,3], k = 2
-<strong>Output:</strong> [3,3]
-<strong>Explanation:</strong>
-The subsequence has the largest sum of 3 + 3 = 6.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,-2,3,4], k = 3
-<strong>Output:</strong> [-1,3,4]
-<strong>Explanation:</strong> 
-The subsequence has the largest sum of -1 + 3 + 4 = 6.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,4,3,3], k = 2
-<strong>Output:</strong> [3,4]
-<strong>Explanation:</strong>
-The subsequence has the largest sum of 3 + 4 = 7. 
-Another possible subsequence is [4, 3].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>-10<sup>5</sup>&nbsp;&lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= k &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-From a greedy perspective, what k elements should you pick?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Could you sort the array while maintaining the index?
-</details>
diff --git a/problems/find-substring-with-given-hash-value/README.md b/problems/find-substring-with-given-hash-value/README.md
deleted file mode 100644
index 0c9182b7e..000000000
--- a/problems/find-substring-with-given-hash-value/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-divisions-with-the-highest-score-of-a-binary-array "All Divisions With the Highest Score of a Binary Array")
-　　　　　　　　　　　　　　　　
-[Next >](../groups-of-strings "Groups of Strings")
-
-## [2156. Find Substring With Given Hash Value (Medium)](https://leetcode.com/problems/find-substring-with-given-hash-value "查找给定哈希值的子串")
-
-<p>The hash of a <strong>0-indexed</strong> string <code>s</code> of length <code>k</code>, given integers <code>p</code> and <code>m</code>, is computed using the following function:</p>
-
-<ul>
-	<li><code>hash(s, p, m) = (val(s[0]) * p<sup>0</sup> + val(s[1]) * p<sup>1</sup> + ... + val(s[k-1]) * p<sup>k-1</sup>) mod m</code>.</li>
-</ul>
-
-<p>Where <code>val(s[i])</code> represents the index of <code>s[i]</code> in the alphabet from <code>val(&#39;a&#39;) = 1</code> to <code>val(&#39;z&#39;) = 26</code>.</p>
-
-<p>You are given a string <code>s</code> and the integers <code>power</code>, <code>modulo</code>, <code>k</code>, and <code>hashValue.</code> Return <code>sub</code>,<em> the <strong>first</strong> <strong>substring</strong> of </em><code>s</code><em> of length </em><code>k</code><em> such that </em><code>hash(sub, power, modulo) == hashValue</code>.</p>
-
-<p>The test cases will be generated such that an answer always <strong>exists</strong>.</p>
-
-<p>A <b>substring</b> is a contiguous non-empty sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;, power = 7, modulo = 20, k = 2, hashValue = 0
-<strong>Output:</strong> &quot;ee&quot;
-<strong>Explanation:</strong> The hash of &quot;ee&quot; can be computed to be hash(&quot;ee&quot;, 7, 20) = (5 * 1 + 5 * 7) mod 20 = 40 mod 20 = 0. 
-&quot;ee&quot; is the first substring of length 2 with hashValue 0. Hence, we return &quot;ee&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;fbxzaad&quot;, power = 31, modulo = 100, k = 3, hashValue = 32
-<strong>Output:</strong> &quot;fbx&quot;
-<strong>Explanation:</strong> The hash of &quot;fbx&quot; can be computed to be hash(&quot;fbx&quot;, 31, 100) = (6 * 1 + 2 * 31 + 24 * 31<sup>2</sup>) mod 100 = 23132 mod 100 = 32. 
-The hash of &quot;bxz&quot; can be computed to be hash(&quot;bxz&quot;, 31, 100) = (2 * 1 + 24 * 31 + 26 * 31<sup>2</sup>) mod 100 = 25732 mod 100 = 32. 
-&quot;fbx&quot; is the first substring of length 3 with hashValue 32. Hence, we return &quot;fbx&quot;.
-Note that &quot;bxz&quot; also has a hash of 32 but it appears later than &quot;fbx&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= s.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= power, modulo &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= hashValue &lt; modulo</code></li>
-	<li><code>s</code> consists of lowercase English letters only.</li>
-	<li>The test cases are generated such that an answer always <strong>exists</strong>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can we update the hash value efficiently while iterating instead of recalculating it each time?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the rolling hash method.
-</details>
diff --git a/problems/find-target-indices-after-sorting-array/README.md b/problems/find-target-indices-after-sorting-array/README.md
deleted file mode 100644
index ef7f2708f..000000000
--- a/problems/find-target-indices-after-sorting-array/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-fertile-pyramids-in-a-land "Count Fertile Pyramids in a Land")
-　　　　　　　　　　　　　　　　
-[Next >](../k-radius-subarray-averages "K Radius Subarray Averages")
-
-## [2089. Find Target Indices After Sorting Array (Easy)](https://leetcode.com/problems/find-target-indices-after-sorting-array "找出数组排序后的目标下标")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code> and a target element <code>target</code>.</p>
-
-<p>A <strong>target index</strong> is an index <code>i</code> such that <code>nums[i] == target</code>.</p>
-
-<p>Return <em>a list of the target indices of</em> <code>nums</code> after<em> sorting </em><code>nums</code><em> in <strong>non-decreasing</strong> order</em>. If there are no target indices, return <em>an <strong>empty</strong> list</em>. The returned list must be sorted in <strong>increasing</strong> order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,5,2,3], target = 2
-<strong>Output:</strong> [1,2]
-<strong>Explanation:</strong> After sorting, nums is [1,<u><strong>2</strong></u>,<u><strong>2</strong></u>,3,5].
-The indices where nums[i] == 2 are 1 and 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,5,2,3], target = 3
-<strong>Output:</strong> [3]
-<strong>Explanation:</strong> After sorting, nums is [1,2,2,<u><strong>3</strong></u>,5].
-The index where nums[i] == 3 is 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,5,2,3], target = 5
-<strong>Output:</strong> [4]
-<strong>Explanation:</strong> After sorting, nums is [1,2,2,3,<u><strong>5</strong></u>].
-The index where nums[i] == 5 is 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>1 &lt;= nums[i], target &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try "sorting" the array first.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Now find all indices in the array whose values are equal to target.
-</details>
diff --git a/problems/find-the-celebrity/README.md b/problems/find-the-celebrity/README.md
deleted file mode 100644
index 41679c4a7..000000000
--- a/problems/find-the-celebrity/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../paint-fence "Paint Fence")
-　　　　　　　　　　　　　　　　
-[Next >](../first-bad-version "First Bad Version")
-
-## [277. Find the Celebrity (Medium)](https://leetcode.com/problems/find-the-celebrity "搜寻名人")
-
-<p>Suppose you are at a party with <code>n</code> people (labeled from <code>0</code> to <code>n - 1</code>) and among them, there may exist one celebrity. The definition of a celebrity is that all the other <code>n - 1</code> people know him/her but he/she does not know any of them.</p>
-
-<p>Now you want to find out who the celebrity is or verify that there is not one. The only thing you are allowed to do is to ask questions like: &quot;Hi, A. Do you know B?&quot; to get information of whether A knows B. You need to find out the celebrity (or verify there is not one) by asking as few questions as possible (in the asymptotic sense).</p>
-
-<p>You are given a helper function <code>bool knows(a, b)</code> which tells you whether A knows B. Implement a function <code>int findCelebrity(n)</code>.&nbsp;There will be exactly one celebrity if he/she is in the party. Return the celebrity&#39;s label if there is a celebrity in the party. If there is no celebrity, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/02/277_example_1_bold.PNG" style="width: 186px; height: 181px;" />
-<pre>
-<strong>Input: </strong>graph = <span id="example-input-1-1">[
-&nbsp; [1,1,0],
-&nbsp; [0,1,0],
-&nbsp; [1,1,1]
-]</span>
-<strong>Output: </strong><span id="example-output-1">1</span>
-<strong>Explanation: </strong>There are three persons labeled with 0, 1 and 2. graph[i][j] = 1 means person i knows person j, otherwise graph[i][j] = 0 means person i does not know person j. The celebrity is the person labeled as 1 because both 0 and 2 know him but 1 does not know anybody.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/02/277_example_2.PNG" style="width: 193px; height: 192px;" />
-<pre>
-<strong>Input: </strong>graph = <span id="example-input-2-1">[
-&nbsp; [1,0,1],
-&nbsp; [1,1,0],
-&nbsp; [0,1,1]
-]</span>
-<strong>Output: </strong><span id="example-output-2">-1</span>
-<strong>Explanation: </strong>There is no celebrity.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>The directed graph is represented as an adjacency matrix, which is an&nbsp;<code>n x n</code> matrix where <code>a[i][j] = 1</code> means person&nbsp;<code>i</code> knows person&nbsp;<code>j</code> while&nbsp;<code>a[i][j] = 0</code> means the contrary.</li>
-	<li>Remember that you won&#39;t have direct access to the adjacency matrix.</li>
-</ol>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Similar Questions
-  1. [Find the Town Judge](../find-the-town-judge) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The best hint for this problem can be provided by the following figure:
-
-<br>
-<img src="https://assets.leetcode.com/uploads/2019/10/20/hint_find_celebrity.png" width="700"/>
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Well, if you understood the gist of the above idea, you can extend it to find a candidate that can possibly be a celebrity. Why do we say a "candidate"? That is for you to think. This is clearly a greedy approach to find the answer. However, there is some information that would still remain to be verified without which we can't obtain an answer with certainty. To get that stake in the ground, we would need some more calls to the knows API.
-</details>
diff --git a/problems/find-the-celebrity/find_the_celebrity.go b/problems/find-the-celebrity/find_the_celebrity.go
deleted file mode 100644
index f701a935b..000000000
--- a/problems/find-the-celebrity/find_the_celebrity.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem277
diff --git a/problems/find-the-celebrity/find_the_celebrity_test.go b/problems/find-the-celebrity/find_the_celebrity_test.go
deleted file mode 100644
index f701a935b..000000000
--- a/problems/find-the-celebrity/find_the_celebrity_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem277
diff --git a/problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance/README.md b/problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance/README.md
deleted file mode 100644
index fe8cd7fdf..000000000
--- a/problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../filter-restaurants-by-vegan-friendly-price-and-distance "Filter Restaurants by Vegan-Friendly, Price and Distance")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-difficulty-of-a-job-schedule "Minimum Difficulty of a Job Schedule")
-
-## [1334. Find the City With the Smallest Number of Neighbors at a Threshold Distance (Medium)](https://leetcode.com/problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance "阈值距离内邻居最少的城市")
-
-<p>There are <code>n</code> cities numbered from <code>0</code> to <code>n-1</code>. Given the array <code>edges</code> where <code>edges[i] = [from<sub>i</sub>, to<sub>i</sub>, weight<sub>i</sub>]</code> represents a bidirectional and weighted edge between cities <code>from<sub>i</sub></code> and <code>to<sub>i</sub></code>, and given the integer <code>distanceThreshold</code>.</p>
-
-<p>Return the city with the smallest number of cities that are reachable through some path and whose distance is <strong>at most</strong> <code>distanceThreshold</code>, If there are multiple such cities, return the city with the greatest number.</p>
-
-<p>Notice that the distance of a path connecting cities <em><strong>i</strong></em> and <em><strong>j</strong></em> is equal to the sum of the edges&#39; weights along that path.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/16/find_the_city_01.png" style="width: 300px; height: 225px;" />
-<pre>
-<strong>Input:</strong> n = 4, edges = [[0,1,3],[1,2,1],[1,3,4],[2,3,1]], distanceThreshold = 4
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>The figure above describes the graph.&nbsp;
-The neighboring cities at a distanceThreshold = 4 for each city are:
-City 0 -&gt; [City 1, City 2]&nbsp;
-City 1 -&gt; [City 0, City 2, City 3]&nbsp;
-City 2 -&gt; [City 0, City 1, City 3]&nbsp;
-City 3 -&gt; [City 1, City 2]&nbsp;
-Cities 0 and 3 have 2 neighboring cities at a distanceThreshold = 4, but we have to return city 3 since it has the greatest number.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/16/find_the_city_02.png" style="width: 300px; height: 225px;" />
-<pre>
-<strong>Input:</strong> n = 5, edges = [[0,1,2],[0,4,8],[1,2,3],[1,4,2],[2,3,1],[3,4,1]], distanceThreshold = 2
-<strong>Output:</strong> 0
-<strong>Explanation: </strong>The figure above describes the graph.&nbsp;
-The neighboring cities at a distanceThreshold = 2 for each city are:
-City 0 -&gt; [City 1]&nbsp;
-City 1 -&gt; [City 0, City 4]&nbsp;
-City 2 -&gt; [City 3, City 4]&nbsp;
-City 3 -&gt; [City 2, City 4]
-City 4 -&gt; [City 1, City 2, City 3]&nbsp;
-The city 0 has 1 neighboring city at a distanceThreshold = 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= edges.length &lt;= n * (n - 1) / 2</code></li>
-	<li><code>edges[i].length == 3</code></li>
-	<li><code>0 &lt;= from<sub>i</sub> &lt; to<sub>i</sub> &lt; n</code></li>
-	<li><code>1 &lt;= weight<sub>i</sub>,&nbsp;distanceThreshold &lt;= 10^4</code></li>
-	<li>All pairs <code>(from<sub>i</sub>, to<sub>i</sub>)</code> are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-
-### Similar Questions
-  1. [Second Minimum Time to Reach Destination](../second-minimum-time-to-reach-destination) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use Floyd-Warshall's algorithm to compute any-point to any-point distances. (Or can also do Dijkstra from every node due to the weights are non-negative).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each city calculate the number of reachable cities within the threshold, then search for the optimal city.
-</details>
diff --git a/problems/find-the-closest-palindrome/README.md b/problems/find-the-closest-palindrome/README.md
deleted file mode 100644
index 59015a153..000000000
--- a/problems/find-the-closest-palindrome/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-tilt "Binary Tree Tilt")
-　　　　　　　　　　　　　　　　
-[Next >](../array-nesting "Array Nesting")
-
-## [564. Find the Closest Palindrome (Hard)](https://leetcode.com/problems/find-the-closest-palindrome "寻找最近的回文数")
-
-<p>Given a string <code>n</code> representing an integer, return <em>the closest integer (not including itself), which is a palindrome</em>. If there is a tie, return <em><strong>the smaller one</strong></em>.</p>
-
-<p>The closest is defined as the absolute difference minimized between two integers.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;123&quot;
-<strong>Output:</strong> &quot;121&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;1&quot;
-<strong>Output:</strong> &quot;0&quot;
-<strong>Explanation:</strong> 0 and 2 are the closest palindromes but we return the smallest which is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n.length &lt;= 18</code></li>
-	<li><code>n</code> consists of only digits.</li>
-	<li><code>n</code> does not have leading zeros.</li>
-	<li><code>n</code> is representing an integer in the range <code>[1, 10<sup>18</sup> - 1]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Next Palindrome Using Same Digits](../next-palindrome-using-same-digits) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Will brute force work for this problem? Think of something else.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Take some examples like 1234, 999,1000, etc and check their closest palindromes. How many different cases are possible?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Do we have to consider only left half or right half of the string or both?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Try to find the closest palindrome of these numbers- 12932, 99800, 12120. Did you observe something?
-</details>
diff --git a/problems/find-the-closest-palindrome/find_the_closest_palindrome.go b/problems/find-the-closest-palindrome/find_the_closest_palindrome.go
deleted file mode 100644
index 514f80ae9..000000000
--- a/problems/find-the-closest-palindrome/find_the_closest_palindrome.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem564
diff --git a/problems/find-the-closest-palindrome/find_the_closest_palindrome_test.go b/problems/find-the-closest-palindrome/find_the_closest_palindrome_test.go
deleted file mode 100644
index 514f80ae9..000000000
--- a/problems/find-the-closest-palindrome/find_the_closest_palindrome_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem564
diff --git a/problems/find-the-derangement-of-an-array/README.md b/problems/find-the-derangement-of-an-array/README.md
deleted file mode 100644
index 0bfe1bf04..000000000
--- a/problems/find-the-derangement-of-an-array/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-square-numbers "Sum of Square Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../design-log-storage-system "Design Log Storage System")
-
-## [634. Find the Derangement of An Array (Medium)](https://leetcode.com/problems/find-the-derangement-of-an-array "寻找数组的错位排列")
-
-<p>
-In combinatorial mathematics, a derangement is a permutation of the elements of a set, such that no element appears in its original position.
-</p>
-
-<p>
-There's originally an array consisting of <code>n</code> integers from 1 to <code>n</code> in ascending order, you need to find the number of derangement it can generate.
-</p>
-
-<p>
-Also, since the answer may be very large, you should return the output mod 10<sup>9</sup> + 7.
-</p>
-
-<p><b>Example 1:</b><br />
-<pre>
-<b>Input:</b> 3
-<b>Output:</b> 2
-<b>Explanation:</b> The original array is [1,2,3]. The two derangements are [2,3,1] and [3,1,2].
-</pre>
-</p>
-
-<p><b>Note:</b><br/>
-<code>n</code> is in the range of [1, 10<sup>6</sup>].
-</p>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/find-the-derangement-of-an-array/find_the_derangement_of_an_array.go b/problems/find-the-derangement-of-an-array/find_the_derangement_of_an_array.go
deleted file mode 100644
index 3788f695d..000000000
--- a/problems/find-the-derangement-of-an-array/find_the_derangement_of_an_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem634
diff --git a/problems/find-the-derangement-of-an-array/find_the_derangement_of_an_array_test.go b/problems/find-the-derangement-of-an-array/find_the_derangement_of_an_array_test.go
deleted file mode 100644
index 3788f695d..000000000
--- a/problems/find-the-derangement-of-an-array/find_the_derangement_of_an_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem634
diff --git a/problems/find-the-difference/README.md b/problems/find-the-difference/README.md
deleted file mode 100644
index 26f99b8ad..000000000
--- a/problems/find-the-difference/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-absolute-file-path "Longest Absolute File Path")
-　　　　　　　　　　　　　　　　
-[Next >](../elimination-game "Elimination Game")
-
-## [389. Find the Difference (Easy)](https://leetcode.com/problems/find-the-difference "找不同")
-
-<p>You are given two strings <code>s</code> and <code>t</code>.</p>
-
-<p>String <code>t</code> is generated by random shuffling string <code>s</code> and then add one more letter at a random position.</p>
-
-<p>Return the letter that was added to <code>t</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcd&quot;, t = &quot;abcde&quot;
-<strong>Output:</strong> &quot;e&quot;
-<strong>Explanation:</strong> &#39;e&#39; is the letter that was added.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;&quot;, t = &quot;y&quot;
-<strong>Output:</strong> &quot;y&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a&quot;, t = &quot;aa&quot;
-<strong>Output:</strong> &quot;a&quot;
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ae&quot;, t = &quot;aea&quot;
-<strong>Output:</strong> &quot;a&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>t.length == s.length + 1</code></li>
-	<li><code>s</code> and <code>t</code> consist of lower-case English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Single Number](../single-number) (Easy)
diff --git a/problems/find-the-difference/find_the_difference.go b/problems/find-the-difference/find_the_difference.go
deleted file mode 100644
index 27ec8816e..000000000
--- a/problems/find-the-difference/find_the_difference.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem389
diff --git a/problems/find-the-difference/find_the_difference_test.go b/problems/find-the-difference/find_the_difference_test.go
deleted file mode 100644
index 27ec8816e..000000000
--- a/problems/find-the-difference/find_the_difference_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem389
diff --git a/problems/find-the-distance-value-between-two-arrays/README.md b/problems/find-the-distance-value-between-two-arrays/README.md
deleted file mode 100644
index 6bd0eda3c..000000000
--- a/problems/find-the-distance-value-between-two-arrays/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../total-sales-amount-by-year "Total Sales Amount by Year")
-　　　　　　　　　　　　　　　　
-[Next >](../cinema-seat-allocation "Cinema Seat Allocation")
-
-## [1385. Find the Distance Value Between Two Arrays (Easy)](https://leetcode.com/problems/find-the-distance-value-between-two-arrays "两个数组间的距离值")
-
-<p>Given two integer arrays <code>arr1</code> and <code>arr2</code>, and the integer <code>d</code>, <em>return the distance value between the two arrays</em>.</p>
-
-<p>The distance value is defined as the number of elements <code>arr1[i]</code> such that there is not any element <code>arr2[j]</code> where <code>|arr1[i]-arr2[j]| &lt;= d</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [4,5,8], arr2 = [10,9,1,8], d = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-For arr1[0]=4 we have: 
-|4-10|=6 &gt; d=2 
-|4-9|=5 &gt; d=2 
-|4-1|=3 &gt; d=2 
-|4-8|=4 &gt; d=2 
-For arr1[1]=5 we have: 
-|5-10|=5 &gt; d=2 
-|5-9|=4 &gt; d=2 
-|5-1|=4 &gt; d=2 
-|5-8|=3 &gt; d=2
-For arr1[2]=8 we have:
-<strong>|8-10|=2 &lt;= d=2</strong>
-<strong>|8-9|=1 &lt;= d=2</strong>
-|8-1|=7 &gt; d=2
-<strong>|8-8|=0 &lt;= d=2</strong>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [1,4,2,3], arr2 = [-4,-3,6,10,20,30], d = 3
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [2,1,100,3], arr2 = [-5,-2,10,-3,7], d = 6
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr1.length, arr2.length &lt;= 500</code></li>
-	<li><code>-1000 &lt;= arr1[i], arr2[j] &lt;= 1000</code></li>
-	<li><code>0 &lt;= d &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort 'arr2' and use binary search to get the closest element for each 'arr1[i]', it gives a time complexity of O(nlogn).
-</details>
diff --git a/problems/find-the-duplicate-number/README.md b/problems/find-the-duplicate-number/README.md
deleted file mode 100644
index aa3962156..000000000
--- a/problems/find-the-duplicate-number/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../walls-and-gates "Walls and Gates")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-word-abbreviation "Unique Word Abbreviation")
-
-## [287. Find the Duplicate Number (Medium)](https://leetcode.com/problems/find-the-duplicate-number "寻找重复数")
-
-<p>Given an array of integers <code>nums</code> containing&nbsp;<code>n + 1</code> integers where each integer is in the range <code>[1, n]</code> inclusive.</p>
-
-<p>There is only <strong>one repeated number</strong> in <code>nums</code>, return <em>this&nbsp;repeated&nbsp;number</em>.</p>
-
-<p>You must solve the problem <strong>without</strong> modifying the array <code>nums</code>&nbsp;and uses only constant extra space.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,3,4,2,2]
-<strong>Output:</strong> 2
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [3,1,3,4,2]
-<strong>Output:</strong> 3
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1]
-<strong>Output:</strong> 1
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1,2]
-<strong>Output:</strong> 1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums.length == n + 1</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= n</code></li>
-	<li>All the integers in <code>nums</code> appear only <strong>once</strong> except for <strong>precisely one integer</strong> which appears <strong>two or more</strong> times.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><b>Follow up:</b></p>
-
-<ul>
-	<li>How can we prove that at least one duplicate number must exist in <code>nums</code>?</li>
-	<li>Can you solve the problem in linear runtime complexity?</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [First Missing Positive](../first-missing-positive) (Hard)
-  1. [Single Number](../single-number) (Easy)
-  1. [Linked List Cycle II](../linked-list-cycle-ii) (Medium)
-  1. [Missing Number](../missing-number) (Easy)
-  1. [Set Mismatch](../set-mismatch) (Easy)
diff --git a/problems/find-the-duplicate-number/find_the_duplicate_number.go b/problems/find-the-duplicate-number/find_the_duplicate_number.go
deleted file mode 100644
index b3ced95a6..000000000
--- a/problems/find-the-duplicate-number/find_the_duplicate_number.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem287
diff --git a/problems/find-the-duplicate-number/find_the_duplicate_number_test.go b/problems/find-the-duplicate-number/find_the_duplicate_number_test.go
deleted file mode 100644
index b3ced95a6..000000000
--- a/problems/find-the-duplicate-number/find_the_duplicate_number_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem287
diff --git a/problems/find-the-highest-altitude/README.md b/problems/find-the-highest-altitude/README.md
deleted file mode 100644
index d4cdabadb..000000000
--- a/problems/find-the-highest-altitude/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-employees-which-report-to-each-employee "The Number of Employees Which Report to Each Employee")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-people-to-teach "Minimum Number of People to Teach")
-
-## [1732. Find the Highest Altitude (Easy)](https://leetcode.com/problems/find-the-highest-altitude "找到最高海拔")
-
-<p>There is a biker going on a road trip. The road trip consists of <code>n + 1</code> points at different altitudes. The biker starts his trip on point <code>0</code> with altitude equal <code>0</code>.</p>
-
-<p>You are given an integer array <code>gain</code> of length <code>n</code> where <code>gain[i]</code> is the <strong>net gain in altitude</strong> between points <code>i</code>​​​​​​ and <code>i + 1</code> for all (<code>0 &lt;= i &lt; n)</code>. Return <em>the <strong>highest altitude</strong> of a point.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> gain = [-5,1,5,0,-7]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The altitudes are [0,-5,-4,1,1,-6]. The highest is 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> gain = [-4,-3,-2,-1,4,3,2]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The altitudes are [0,-4,-7,-9,-10,-6,-3,-1]. The highest is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == gain.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>-100 &lt;= gain[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's note that the altitude of an element is the sum of gains of all the elements behind it
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Getting the altitudes can be done by getting the prefix sum array of the given array
-</details>
diff --git a/problems/find-the-index-of-the-large-integer/README.md b/problems/find-the-index-of-the-large-integer/README.md
deleted file mode 100644
index 4206c138e..000000000
--- a/problems/find-the-index-of-the-large-integer/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-most-recent-three-orders "The Most Recent Three Orders")
-　　　　　　　　　　　　　　　　
-[Next >](../count-good-triplets "Count Good Triplets")
-
-## [1533. Find the Index of the Large Integer (Medium)](https://leetcode.com/problems/find-the-index-of-the-large-integer "找到最大整数的索引")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do a binary search over the array, exclude the half of the array that doesn't contain the largest number.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep shrinking the search space till it reaches the size of 2 where you can easily determine which one has the largest integer.
-</details>
diff --git a/problems/find-the-kth-largest-integer-in-the-array/README.md b/problems/find-the-kth-largest-integer-in-the-array/README.md
deleted file mode 100644
index 26ca0ca05..000000000
--- a/problems/find-the-kth-largest-integer-in-the-array/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-difference-between-highest-and-lowest-of-k-scores "Minimum Difference Between Highest and Lowest of K Scores")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-work-sessions-to-finish-the-tasks "Minimum Number of Work Sessions to Finish the Tasks")
-
-## [1985. Find the Kth Largest Integer in the Array (Medium)](https://leetcode.com/problems/find-the-kth-largest-integer-in-the-array "找出数组中的第 K 大整数")
-
-<p>You are given an array of strings <code>nums</code> and an integer <code>k</code>. Each string in <code>nums</code> represents an integer without leading zeros.</p>
-
-<p>Return <em>the string that represents the </em><code>k<sup>th</sup></code><em><strong> largest integer</strong> in </em><code>nums</code>.</p>
-
-<p><strong>Note</strong>: Duplicate numbers should be counted distinctly. For example, if <code>nums</code> is <code>[&quot;1&quot;,&quot;2&quot;,&quot;2&quot;]</code>, <code>&quot;2&quot;</code> is the first largest integer, <code>&quot;2&quot;</code> is the second-largest integer, and <code>&quot;1&quot;</code> is the third-largest integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [&quot;3&quot;,&quot;6&quot;,&quot;7&quot;,&quot;10&quot;], k = 4
-<strong>Output:</strong> &quot;3&quot;
-<strong>Explanation:</strong>
-The numbers in nums sorted in non-decreasing order are [&quot;3&quot;,&quot;6&quot;,&quot;7&quot;,&quot;10&quot;].
-The 4<sup>th</sup> largest integer in nums is &quot;3&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [&quot;2&quot;,&quot;21&quot;,&quot;12&quot;,&quot;1&quot;], k = 3
-<strong>Output:</strong> &quot;2&quot;
-<strong>Explanation:</strong>
-The numbers in nums sorted in non-decreasing order are [&quot;1&quot;,&quot;2&quot;,&quot;12&quot;,&quot;21&quot;].
-The 3<sup>rd</sup> largest integer in nums is &quot;2&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [&quot;0&quot;,&quot;0&quot;], k = 2
-<strong>Output:</strong> &quot;0&quot;
-<strong>Explanation:</strong>
-The numbers in nums sorted in non-decreasing order are [&quot;0&quot;,&quot;0&quot;].
-The 2<sup>nd</sup> largest integer in nums is &quot;0&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i].length &lt;= 100</code></li>
-	<li><code>nums[i]</code> consists of only digits.</li>
-	<li><code>nums[i]</code> will not have any leading zeros.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Quickselect](../../tag/quickselect/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If two numbers have different lengths, which one will be larger?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The longer number is the larger number.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If two numbers have the same length, which one will be larger?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Compare the two numbers starting from the most significant digit. Once you have found the first digit that differs, the one with the larger digit is the larger number.
-</details>
diff --git a/problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows/README.md b/problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows/README.md
deleted file mode 100644
index 04ac15592..000000000
--- a/problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit "Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit")
-　　　　　　　　　　　　　　　　
-[Next >](../evaluate-boolean-expression "Evaluate Boolean Expression")
-
-## [1439. Find the Kth Smallest Sum of a Matrix With Sorted Rows (Hard)](https://leetcode.com/problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows "有序矩阵中的第 k 个最小数组和")
-
-<p>You are given an <code>m x n</code> matrix <code>mat</code> that has its rows sorted in non-decreasing order and an integer <code>k</code>.</p>
-
-<p>You are allowed to choose <strong>exactly one element</strong> from each row to form an array.</p>
-
-<p>Return <em>the </em><code>k<sup>th</sup></code><em> smallest array sum among all possible arrays</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[1,3,11],[2,4,6]], k = 5
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> Choosing one element from each row, the first k smallest sum are:
-[1,2], [1,4], [3,2], [3,4], [1,6]. Where the 5th sum is 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[1,3,11],[2,4,6]], k = 9
-<strong>Output:</strong> 17
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[1,10,10],[1,4,5],[2,3,6]], k = 7
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> Choosing one element from each row, the first k smallest sum are:
-[1,1,2], [1,1,3], [1,4,2], [1,4,3], [1,1,6], [1,5,2], [1,5,3]. Where the 7th sum is 9.  
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat.length[i]</code></li>
-	<li><code>1 &lt;= m, n &lt;= 40</code></li>
-	<li><code>1 &lt;= mat[i][j] &lt;= 5000</code></li>
-	<li><code>1 &lt;= k &lt;= min(200, n<sup>m</sup>)</code></li>
-	<li><code>mat[i]</code> is a non-decreasing array.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Save all visited sums and corresponding indexes in a priority queue. Then, once you pop the smallest sum so far, you can quickly identify the next m candidates for smallest sum by incrementing each row index by 1.
-</details>
diff --git a/problems/find-the-longest-substring-containing-vowels-in-even-counts/README.md b/problems/find-the-longest-substring-containing-vowels-in-even-counts/README.md
deleted file mode 100644
index 686360ad1..000000000
--- a/problems/find-the-longest-substring-containing-vowels-in-even-counts/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../increasing-decreasing-string "Increasing Decreasing String")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-zigzag-path-in-a-binary-tree "Longest ZigZag Path in a Binary Tree")
-
-## [1371. Find the Longest Substring Containing Vowels in Even Counts (Medium)](https://leetcode.com/problems/find-the-longest-substring-containing-vowels-in-even-counts "每个元音包含偶数次的最长子字符串")
-
-<p>Given the string <code>s</code>, return the size of the longest substring containing each vowel an even number of times. That is, &#39;a&#39;, &#39;e&#39;, &#39;i&#39;, &#39;o&#39;, and &#39;u&#39; must appear an even number of times.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;eleetminicoworoep&quot;
-<strong>Output:</strong> 13
-<strong>Explanation: </strong>The longest substring is &quot;leetminicowor&quot; which contains two each of the vowels: <strong>e</strong>, <strong>i</strong> and <strong>o</strong> and zero of the vowels: <strong>a</strong> and <strong>u</strong>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcodeisgreat&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The longest substring is &quot;leetc&quot; which contains two e&#39;s.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bcbcbc&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> In this case, the given string &quot;bcbcbc&quot; is the longest because all vowels: <strong>a</strong>, <strong>e</strong>, <strong>i</strong>, <strong>o</strong> and <strong>u</strong> appear zero times.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 5 x 10^5</code></li>
-	<li><code>s</code>&nbsp;contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Represent the counts (odd or even) of vowels with a bitmask.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Precompute the prefix xor for the bitmask of vowels and then get the longest valid substring.
-</details>
diff --git a/problems/find-the-longest-valid-obstacle-course-at-each-position/README.md b/problems/find-the-longest-valid-obstacle-course-at-each-position/README.md
deleted file mode 100644
index 92086d4ed..000000000
--- a/problems/find-the-longest-valid-obstacle-course-at-each-position/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-swaps-to-make-the-string-balanced "Minimum Number of Swaps to Make the String Balanced")
-　　　　　　　　　　　　　　　　
-[Next >](../employees-with-missing-information "Employees With Missing Information")
-
-## [1964. Find the Longest Valid Obstacle Course at Each Position (Hard)](https://leetcode.com/problems/find-the-longest-valid-obstacle-course-at-each-position "找出到每个位置为止最长的有效障碍赛跑路线")
-
-<p>You want to build some obstacle courses. You are given a <strong>0-indexed</strong> integer array <code>obstacles</code> of length <code>n</code>, where <code>obstacles[i]</code> describes the height of the <code>i<sup>th</sup></code> obstacle.</p>
-
-<p>For every index <code>i</code> between <code>0</code> and <code>n - 1</code> (<strong>inclusive</strong>), find the length of the <strong>longest obstacle course</strong> in <code>obstacles</code> such that:</p>
-
-<ul>
-	<li>You choose any number of obstacles between <code>0</code> and <code>i</code> <strong>inclusive</strong>.</li>
-	<li>You must include the <code>i<sup>th</sup></code> obstacle in the course.</li>
-	<li>You must put the chosen obstacles in the <strong>same order</strong> as they appear in <code>obstacles</code>.</li>
-	<li>Every obstacle (except the first) is <strong>taller</strong> than or the <strong>same height</strong> as the obstacle immediately before it.</li>
-</ul>
-
-<p>Return <em>an array</em> <code>ans</code> <em>of length</em> <code>n</code>, <em>where</em> <code>ans[i]</code> <em>is the length of the <strong>longest obstacle course</strong> for index</em> <code>i</code><em> as described above</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> obstacles = [1,2,3,2]
-<strong>Output:</strong> [1,2,3,3]
-<strong>Explanation:</strong> The longest valid obstacle course at each position is:
-- i = 0: [<u>1</u>], [1] has length 1.
-- i = 1: [<u>1</u>,<u>2</u>], [1,2] has length 2.
-- i = 2: [<u>1</u>,<u>2</u>,<u>3</u>], [1,2,3] has length 3.
-- i = 3: [<u>1</u>,<u>2</u>,3,<u>2</u>], [1,2,2] has length 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> obstacles = [2,2,1]
-<strong>Output:</strong> [1,2,1]
-<strong>Explanation: </strong>The longest valid obstacle course at each position is:
-- i = 0: [<u>2</u>], [2] has length 1.
-- i = 1: [<u>2</u>,<u>2</u>], [2,2] has length 2.
-- i = 2: [2,2,<u>1</u>], [1] has length 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> obstacles = [3,1,5,6,4,2]
-<strong>Output:</strong> [1,1,2,3,2,2]
-<strong>Explanation:</strong> The longest valid obstacle course at each position is:
-- i = 0: [<u>3</u>], [3] has length 1.
-- i = 1: [3,<u>1</u>], [1] has length 1.
-- i = 2: [<u>3</u>,1,<u>5</u>], [3,5] has length 2. [1,5] is also valid.
-- i = 3: [<u>3</u>,1,<u>5</u>,<u>6</u>], [3,5,6] has length 3. [1,5,6] is also valid.
-- i = 4: [<u>3</u>,1,5,6,<u>4</u>], [3,4] has length 2. [1,4] is also valid.
-- i = 5: [3,<u>1</u>,5,6,4,<u>2</u>], [1,2] has length 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == obstacles.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= obstacles[i] &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you keep track of the minimum height for each obstacle course length?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can use binary search to find the longest previous obstacle course length that satisfies the conditions.
-</details>
diff --git a/problems/find-the-middle-index-in-array/README.md b/problems/find-the-middle-index-in-array/README.md
deleted file mode 100644
index 5a9991797..000000000
--- a/problems/find-the-middle-index-in-array/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-the-number-of-experiments "Count the Number of Experiments")
-　　　　　　　　　　　　　　　　
-[Next >](../find-all-groups-of-farmland "Find All Groups of Farmland")
-
-## [1991. Find the Middle Index in Array (Easy)](https://leetcode.com/problems/find-the-middle-index-in-array "找到数组的中间位置")
-
-<p>Given a <strong>0-indexed</strong> integer array <code>nums</code>, find the <strong>leftmost</strong> <code>middleIndex</code> (i.e., the smallest amongst all the possible ones).</p>
-
-<p>A <code>middleIndex</code> is an index where <code>nums[0] + nums[1] + ... + nums[middleIndex-1] == nums[middleIndex+1] + nums[middleIndex+2] + ... + nums[nums.length-1]</code>.</p>
-
-<p>If <code>middleIndex == 0</code>, the left side sum is considered to be <code>0</code>. Similarly, if <code>middleIndex == nums.length - 1</code>, the right side sum is considered to be <code>0</code>.</p>
-
-<p>Return <em>the <strong>leftmost</strong> </em><code>middleIndex</code><em> that satisfies the condition, or </em><code>-1</code><em> if there is no such index</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,-1,<u>8</u>,4]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The sum of the numbers before index 3 is: 2 + 3 + -1 = 4
-The sum of the numbers after index 3 is: 4 = 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,-1,<u>4</u>]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The sum of the numbers before index 2 is: 1 + -1 = 0
-The sum of the numbers after index 2 is: 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,5]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There is no valid middleIndex.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>-1000 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as&nbsp;724:&nbsp;<a href="https://leetcode.com/problems/find-pivot-index/" target="_blank">https://leetcode.com/problems/find-pivot-index/</a></p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could we go from left to right and check to see if an index is a middle index?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Do we need to sum every number to the left and right of an index each time?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use a prefix sum array where prefix[i] = nums[0] + nums[1] + ... + nums[i].
-</details>
diff --git a/problems/find-the-minimum-and-maximum-number-of-nodes-between-critical-points/README.md b/problems/find-the-minimum-and-maximum-number-of-nodes-between-critical-points/README.md
deleted file mode 100644
index e614c8384..000000000
--- a/problems/find-the-minimum-and-maximum-number-of-nodes-between-critical-points/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-index-with-equal-value "Smallest Index With Equal Value")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-operations-to-convert-number "Minimum Operations to Convert Number")
-
-## [2058. Find the Minimum and Maximum Number of Nodes Between Critical Points (Medium)](https://leetcode.com/problems/find-the-minimum-and-maximum-number-of-nodes-between-critical-points "找出临界点之间的最小和最大距离")
-
-<p>A <strong>critical point</strong> in a linked list is defined as <strong>either</strong> a <strong>local maxima</strong> or a <strong>local minima</strong>.</p>
-
-<p>A node is a <strong>local maxima</strong> if the current node has a value <strong>strictly greater</strong> than the previous node and the next node.</p>
-
-<p>A node is a <strong>local minima</strong> if the current node has a value <strong>strictly smaller</strong> than the previous node and the next node.</p>
-
-<p>Note that a node can only be a local maxima/minima if there exists <strong>both</strong> a previous node and a next node.</p>
-
-<p>Given a linked list <code>head</code>, return <em>an array of length 2 containing </em><code>[minDistance, maxDistance]</code><em> where </em><code>minDistance</code><em> is the <strong>minimum distance</strong> between <strong>any&nbsp;two distinct</strong> critical points and </em><code>maxDistance</code><em> is the <strong>maximum distance</strong> between <strong>any&nbsp;two distinct</strong> critical points. If there are <strong>fewer</strong> than two critical points, return </em><code>[-1, -1]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/13/a1.png" style="width: 148px; height: 55px;" />
-<pre>
-<strong>Input:</strong> head = [3,1]
-<strong>Output:</strong> [-1,-1]
-<strong>Explanation:</strong> There are no critical points in [3,1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/13/a2.png" style="width: 624px; height: 46px;" />
-<pre>
-<strong>Input:</strong> head = [5,3,1,2,5,1,2]
-<strong>Output:</strong> [1,3]
-<strong>Explanation:</strong> There are three critical points:
-- [5,3,<strong><u>1</u></strong>,2,5,1,2]: The third node is a local minima because 1 is less than 3 and 2.
-- [5,3,1,2,<u><strong>5</strong></u>,1,2]: The fifth node is a local maxima because 5 is greater than 2 and 1.
-- [5,3,1,2,5,<u><strong>1</strong></u>,2]: The sixth node is a local minima because 1 is less than 5 and 2.
-The minimum distance is between the fifth and the sixth node. minDistance = 6 - 5 = 1.
-The maximum distance is between the third and the sixth node. maxDistance = 6 - 3 = 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/14/a5.png" style="width: 624px; height: 39px;" />
-<pre>
-<strong>Input:</strong> head = [1,3,2,2,3,2,2,2,7]
-<strong>Output:</strong> [3,3]
-<strong>Explanation:</strong> There are two critical points:
-- [1,<u><strong>3</strong></u>,2,2,3,2,2,2,7]: The second node is a local maxima because 3 is greater than 1 and 2.
-- [1,3,2,2,<u><strong>3</strong></u>,2,2,2,7]: The fifth node is a local maxima because 3 is greater than 2 and 2.
-Both the minimum and maximum distances are between the second and the fifth node.
-Thus, minDistance and maxDistance is 5 - 2 = 3.
-Note that the last node is not considered a local maxima because it does not have a next node.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[2, 10<sup>5</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The maximum distance must be the distance between the first and last critical point.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each adjacent critical point, calculate the difference and check if it is the minimum distance.
-</details>
diff --git a/problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k/README.md b/problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k/README.md
deleted file mode 100644
index 1d1f7e2c6..000000000
--- a/problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-value-to-get-positive-step-by-step-sum "Minimum Value to Get Positive Step by Step Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../the-k-th-lexicographical-string-of-all-happy-strings-of-length-n "The k-th Lexicographical String of All Happy Strings of Length n")
-
-## [1414. Find the Minimum Number of Fibonacci Numbers Whose Sum Is K (Medium)](https://leetcode.com/problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k "和为 K 的最少斐波那契数字数目")
-
-<p>Given an integer&nbsp;<code>k</code>, <em>return the minimum number of Fibonacci numbers whose sum is equal to </em><code>k</code>. The same Fibonacci number can be used multiple times.</p>
-
-<p>The Fibonacci numbers are defined as:</p>
-
-<ul>
-	<li><code>F<sub>1</sub> = 1</code></li>
-	<li><code>F<sub>2</sub> = 1</code></li>
-	<li><code>F<sub>n</sub> = F<sub>n-1</sub> + F<sub>n-2</sub></code> for <code>n &gt; 2.</code></li>
-</ul>
-It is guaranteed that for the given constraints we can always find such Fibonacci numbers that sum up to <code>k</code>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 7
-<strong>Output:</strong> 2 
-<strong>Explanation:</strong> The Fibonacci numbers are: 1, 1, 2, 3, 5, 8, 13, ... 
-For k = 7 we can use 2 + 5 = 7.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 10
-<strong>Output:</strong> 2 
-<strong>Explanation:</strong> For k = 10 we can use 2 + 8 = 10.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 19
-<strong>Output:</strong> 3 
-<strong>Explanation:</strong> For k = 19 we can use 1 + 5 + 13 = 19.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Generate all Fibonacci numbers up to the limit (they are few).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use greedy solution, taking at every time the greatest Fibonacci number which is smaller than or equal to the current number. Subtract this Fibonacci number from the current number and repeat again the process.
-</details>
diff --git a/problems/find-the-missing-ids/README.md b/problems/find-the-missing-ids/README.md
deleted file mode 100644
index ad3d152ac..000000000
--- a/problems/find-the-missing-ids/README.md
+++ /dev/null
@@ -1,22 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-two-expression-trees-are-equivalent "Check If Two Expression Trees are Equivalent")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-nesting-depth-of-the-parentheses "Maximum Nesting Depth of the Parentheses")
-
-## [1613. Find the Missing IDs (Medium)](https://leetcode.com/problems/find-the-missing-ids "找到遗失的ID")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Report Contiguous Dates](../report-contiguous-dates) (Hard)
-  1. [Find the Start and End Number of Continuous Ranges](../find-the-start-and-end-number-of-continuous-ranges) (Medium)
-  1. [Number of Transactions per Visit](../number-of-transactions-per-visit) (Hard)
diff --git a/problems/find-the-missing-ids/mysql_schemas.sql b/problems/find-the-missing-ids/mysql_schemas.sql
deleted file mode 100644
index 150f5ff9b..000000000
--- a/problems/find-the-missing-ids/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create table If Not Exists Customers (customer_id int, customer_name varchar(20));
-Truncate table Customers;
-insert into Customers (customer_id, customer_name) values ('1', 'Alice');
-insert into Customers (customer_id, customer_name) values ('4', 'Bob');
-insert into Customers (customer_id, customer_name) values ('5', 'Charlie');
diff --git a/problems/find-the-most-competitive-subsequence/README.md b/problems/find-the-most-competitive-subsequence/README.md
deleted file mode 100644
index 6f21e4840..000000000
--- a/problems/find-the-most-competitive-subsequence/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../richest-customer-wealth "Richest Customer Wealth")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-moves-to-make-array-complementary "Minimum Moves to Make Array Complementary")
-
-## [1673. Find the Most Competitive Subsequence (Medium)](https://leetcode.com/problems/find-the-most-competitive-subsequence "找出最具竞争力的子序列")
-
-<p>Given an integer array <code>nums</code> and a positive integer <code>k</code>, return <em>the most<strong> competitive</strong> subsequence of </em><code>nums</code> <em>of size </em><code>k</code>.</p>
-
-<p>An array&#39;s subsequence is a resulting sequence obtained by erasing some (possibly zero) elements from the array.</p>
-
-<p>We define that a subsequence <code>a</code> is more <strong>competitive</strong> than a subsequence <code>b</code> (of the same length) if in the first position where <code>a</code> and <code>b</code> differ, subsequence <code>a</code> has a number <strong>less</strong> than the corresponding number in <code>b</code>. For example, <code>[1,3,4]</code> is more competitive than <code>[1,3,5]</code> because the first position they differ is at the final number, and <code>4</code> is less than <code>5</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,5,2,6], k = 2
-<strong>Output:</strong> [2,6]
-<strong>Explanation:</strong> Among the set of every possible subsequence: {[3,5], [3,2], [3,6], [5,2], [5,6], [2,6]}, [2,6] is the most competitive.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,4,3,3,5,4,9,6], k = 4
-<strong>Output:</strong> [2,3,3,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= k &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-In lexicographical order, the elements to the left have higher priority than those that come after. Can you think of a strategy that incrementally builds the answer from left to right?
-</details>
diff --git a/problems/find-the-quiet-students-in-all-exams/README.md b/problems/find-the-quiet-students-in-all-exams/README.md
deleted file mode 100644
index 82f0db71d..000000000
--- a/problems/find-the-quiet-students-in-all-exams/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-paint-n-3-grid "Number of Ways to Paint N × 3 Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-value-to-get-positive-step-by-step-sum "Minimum Value to Get Positive Step by Step Sum")
-
-## [1412. Find the Quiet Students in All Exams (Hard)](https://leetcode.com/problems/find-the-quiet-students-in-all-exams "查找成绩处于中游的学生")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/find-the-quiet-students-in-all-exams/mysql_schemas.sql b/problems/find-the-quiet-students-in-all-exams/mysql_schemas.sql
deleted file mode 100644
index 66fe906ec..000000000
--- a/problems/find-the-quiet-students-in-all-exams/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create table If Not Exists Student (student_id int, student_name varchar(30));
-Create table If Not Exists Exam (exam_id int, student_id int, score int);
-Truncate table Student;
-insert into Student (student_id, student_name) values ('1', 'Daniel');
-insert into Student (student_id, student_name) values ('2', 'Jade');
-insert into Student (student_id, student_name) values ('3', 'Stella');
-insert into Student (student_id, student_name) values ('4', 'Jonathan');
-insert into Student (student_id, student_name) values ('5', 'Will');
-Truncate table Exam;
-insert into Exam (exam_id, student_id, score) values ('10', '1', '70');
-insert into Exam (exam_id, student_id, score) values ('10', '2', '80');
-insert into Exam (exam_id, student_id, score) values ('10', '3', '90');
-insert into Exam (exam_id, student_id, score) values ('20', '1', '80');
-insert into Exam (exam_id, student_id, score) values ('30', '1', '70');
-insert into Exam (exam_id, student_id, score) values ('30', '3', '80');
-insert into Exam (exam_id, student_id, score) values ('30', '4', '90');
-insert into Exam (exam_id, student_id, score) values ('40', '1', '60');
-insert into Exam (exam_id, student_id, score) values ('40', '2', '70');
-insert into Exam (exam_id, student_id, score) values ('40', '4', '80');
diff --git a/problems/find-the-shortest-superstring/README.md b/problems/find-the-shortest-superstring/README.md
deleted file mode 100644
index 970d892fd..000000000
--- a/problems/find-the-shortest-superstring/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../di-string-match "DI String Match")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-columns-to-make-sorted "Delete Columns to Make Sorted")
-
-## [943. Find the Shortest Superstring (Hard)](https://leetcode.com/problems/find-the-shortest-superstring "最短超级串")
-
-<p>Given an array of strings <code>words</code>, return <em>the smallest string that contains each string in</em> <code>words</code> <em>as a substring</em>. If there are multiple valid strings of the smallest length, return <strong>any of them</strong>.</p>
-
-<p>You may assume that no string in <code>words</code> is a substring of another string in <code>words</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;alex&quot;,&quot;loves&quot;,&quot;leetcode&quot;]
-<strong>Output:</strong> &quot;alexlovesleetcode&quot;
-<strong>Explanation:</strong> All permutations of &quot;alex&quot;,&quot;loves&quot;,&quot;leetcode&quot; would also be accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;catg&quot;,&quot;ctaagt&quot;,&quot;gcta&quot;,&quot;ttca&quot;,&quot;atgcatc&quot;]
-<strong>Output:</strong> &quot;gctaagttcatgcatc&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 12</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 20</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters.</li>
-	<li>All the strings of <code>words</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
diff --git a/problems/find-the-shortest-superstring/find_the_shortest_superstring.go b/problems/find-the-shortest-superstring/find_the_shortest_superstring.go
deleted file mode 100644
index e232c6d39..000000000
--- a/problems/find-the-shortest-superstring/find_the_shortest_superstring.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem943
diff --git a/problems/find-the-shortest-superstring/find_the_shortest_superstring_test.go b/problems/find-the-shortest-superstring/find_the_shortest_superstring_test.go
deleted file mode 100644
index e232c6d39..000000000
--- a/problems/find-the-shortest-superstring/find_the_shortest_superstring_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem943
diff --git a/problems/find-the-smallest-divisor-given-a-threshold/README.md b/problems/find-the-smallest-divisor-given-a-threshold/README.md
deleted file mode 100644
index 45f02e814..000000000
--- a/problems/find-the-smallest-divisor-given-a-threshold/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../group-the-people-given-the-group-size-they-belong-to "Group the People Given the Group Size They Belong To")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix "Minimum Number of Flips to Convert Binary Matrix to Zero Matrix")
-
-## [1283. Find the Smallest Divisor Given a Threshold (Medium)](https://leetcode.com/problems/find-the-smallest-divisor-given-a-threshold "使结果不超过阈值的最小除数")
-
-<p>Given an array of integers <code>nums</code> and an integer <code>threshold</code>, we will choose a positive integer <code>divisor</code>, divide all the array by it, and sum the division&#39;s result. Find the <strong>smallest</strong> <code>divisor</code> such that the result mentioned above is less than or equal to <code>threshold</code>.</p>
-
-<p>Each result of the division is rounded to the nearest integer greater than or equal to that element. (For example: <code>7/3 = 3</code> and <code>10/2 = 5</code>).</p>
-
-<p>The test cases are generated so&nbsp;that there will be an answer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,5,9], threshold = 6
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> We can get a sum to 17 (1+2+5+9) if the divisor is 1. 
-If the divisor is 4 we can get a sum of 7 (1+1+2+3) and if the divisor is 5 the sum will be 5 (1+1+1+2). 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [44,22,33,11,1], threshold = 5
-<strong>Output:</strong> 44
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>nums.length &lt;= threshold &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Examine every possible number for solution. Choose the largest of them.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use binary search to reduce the time complexity.
-</details>
diff --git a/problems/find-the-start-and-end-number-of-continuous-ranges/README.md b/problems/find-the-start-and-end-number-of-continuous-ranges/README.md
deleted file mode 100644
index 5521814a1..000000000
--- a/problems/find-the-start-and-end-number-of-continuous-ranges/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix "Minimum Number of Flips to Convert Binary Matrix to Zero Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../iterator-for-combination "Iterator for Combination")
-
-## [1285. Find the Start and End Number of Continuous Ranges (Medium)](https://leetcode.com/problems/find-the-start-and-end-number-of-continuous-ranges "找到连续区间的开始和结束数字")
-
-<p>Table: <code>Logs</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| log_id        | int     |
-+---------------+---------+
-id is the primary key for this table.
-Each row of this table contains the ID in a log Table.
-</pre>
-
-Since some IDs have been removed from Logs. Write an SQL query to find the start and end number of continuous ranges in table Logs.
-
-Order the result table by start_id.
-
-The query result format is in the following example:
-<pre>
-Logs table:
-+------------+
-| log_id     |
-+------------+
-| 1          |
-| 2          |
-| 3          |
-| 7          |
-| 8          |
-| 10         |
-+------------+
-
-Result table:
-+------------+--------------+
-| start_id   | end_id       |
-+------------+--------------+
-| 1          | 3            |
-| 7          | 8            |
-| 10         | 10           |
-+------------+--------------+
-The result table should contain all ranges in table Logs.
-From 1 to 3 is contained in the table.
-From 4 to 6 is missing in the table
-From 7 to 8 is contained in the table.
-Number 9 is missing in the table.
-Number 10 is contained in the table.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Report Contiguous Dates](../report-contiguous-dates) (Hard)
-  1. [Find the Missing IDs](../find-the-missing-ids) (Medium)
diff --git a/problems/find-the-start-and-end-number-of-continuous-ranges/mysql_schemas.sql b/problems/find-the-start-and-end-number-of-continuous-ranges/mysql_schemas.sql
deleted file mode 100644
index 3f578ff5a..000000000
--- a/problems/find-the-start-and-end-number-of-continuous-ranges/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Logs (log_id int);
-Truncate table Logs;
-insert into Logs (log_id) values ('1');
-insert into Logs (log_id) values ('2');
-insert into Logs (log_id) values ('3');
-insert into Logs (log_id) values ('7');
-insert into Logs (log_id) values ('8');
-insert into Logs (log_id) values ('10');
diff --git a/problems/find-the-student-that-will-replace-the-chalk/README.md b/problems/find-the-student-that-will-replace-the-chalk/README.md
deleted file mode 100644
index ed3062efa..000000000
--- a/problems/find-the-student-that-will-replace-the-chalk/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-all-the-integers-in-a-range-are-covered "Check if All the Integers in a Range Are Covered")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-magic-square "Largest Magic Square")
-
-## [1894. Find the Student that Will Replace the Chalk (Medium)](https://leetcode.com/problems/find-the-student-that-will-replace-the-chalk "找到需要补充粉笔的学生编号")
-
-<p>There are <code>n</code> students in a class numbered from <code>0</code> to <code>n - 1</code>. The teacher will give each student a problem starting with the student number <code>0</code>, then the student number <code>1</code>, and so on until the teacher reaches the student number <code>n - 1</code>. After that, the teacher will restart the process, starting with the student number <code>0</code> again.</p>
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>chalk</code> and an integer <code>k</code>. There are initially <code>k</code> pieces of chalk. When the student number <code>i</code> is given a problem to solve, they will use <code>chalk[i]</code> pieces of chalk to solve that problem. However, if the current number of chalk pieces is <strong>strictly less</strong> than <code>chalk[i]</code>, then the student number <code>i</code> will be asked to <strong>replace</strong> the chalk.</p>
-
-<p>Return <em>the <strong>index</strong> of the student that will <strong>replace</strong> the chalk</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> chalk = [5,1,5], k = 22
-<strong>Output:</strong> 0
-<strong>Explanation: </strong>The students go in turns as follows:
-- Student number 0 uses 5 chalk, so k = 17.
-- Student number 1 uses 1 chalk, so k = 16.
-- Student number 2 uses 5 chalk, so k = 11.
-- Student number 0 uses 5 chalk, so k = 6.
-- Student number 1 uses 1 chalk, so k = 5.
-- Student number 2 uses 5 chalk, so k = 0.
-Student number 0 does not have enough chalk, so they will have to replace it.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> chalk = [3,4,1,2], k = 25
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>The students go in turns as follows:
-- Student number 0 uses 3 chalk so k = 22.
-- Student number 1 uses 4 chalk so k = 18.
-- Student number 2 uses 1 chalk so k = 17.
-- Student number 3 uses 2 chalk so k = 15.
-- Student number 0 uses 3 chalk so k = 12.
-- Student number 1 uses 4 chalk so k = 8.
-- Student number 2 uses 1 chalk so k = 7.
-- Student number 3 uses 2 chalk so k = 5.
-- Student number 0 uses 3 chalk so k = 2.
-Student number 1 does not have enough chalk, so they will have to replace it.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>chalk.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= chalk[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Subtract the sum of chalk[i] from k until k is less than that sum
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Now just iterate over the array if chalk[i] is less thank k this is your answer otherwise this i is the answer
-</details>
diff --git a/problems/find-the-subtasks-that-did-not-execute/README.md b/problems/find-the-subtasks-that-did-not-execute/README.md
deleted file mode 100644
index 8d94adad5..000000000
--- a/problems/find-the-subtasks-that-did-not-execute/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tree-of-coprimes "Tree of Coprimes")
-　　　　　　　　　　　　　　　　
-[Next >](../merge-strings-alternately "Merge Strings Alternately")
-
-## [1767. Find the Subtasks That Did Not Execute (Hard)](https://leetcode.com/problems/find-the-subtasks-that-did-not-execute "寻找没有被执行的任务对")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/find-the-subtasks-that-did-not-execute/mysql_schemas.sql b/problems/find-the-subtasks-that-did-not-execute/mysql_schemas.sql
deleted file mode 100644
index fd4398ea6..000000000
--- a/problems/find-the-subtasks-that-did-not-execute/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Tasks (task_id int, subtasks_count int);
-Create table If Not Exists Executed (task_id int, subtask_id int);
-Truncate table Tasks;
-insert into Tasks (task_id, subtasks_count) values ('1', '3');
-insert into Tasks (task_id, subtasks_count) values ('2', '2');
-insert into Tasks (task_id, subtasks_count) values ('3', '4');
-Truncate table Executed;
-insert into Executed (task_id, subtask_id) values ('1', '2');
-insert into Executed (task_id, subtask_id) values ('3', '1');
-insert into Executed (task_id, subtask_id) values ('3', '2');
-insert into Executed (task_id, subtask_id) values ('3', '3');
-insert into Executed (task_id, subtask_id) values ('3', '4');
diff --git a/problems/find-the-team-size/README.md b/problems/find-the-team-size/README.md
deleted file mode 100644
index dd11cf0b0..000000000
--- a/problems/find-the-team-size/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../deepest-leaves-sum "Deepest Leaves Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../find-n-unique-integers-sum-up-to-zero "Find N Unique Integers Sum up to Zero")
-
-## [1303. Find the Team Size (Easy)](https://leetcode.com/problems/find-the-team-size "求团队人数")
-
-<p>Table: <code>Employee</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| employee_id   | int     |
-| team_id       | int     |
-+---------------+---------+
-employee_id is the primary key for this table.
-Each row of this table contains the ID of each employee and their respective team.
-</pre>
-
-Write an SQL query to find the team size of each of the employees.
-
-Return result table in any order.
-
-The query result format is in the following example:
-<pre>
-Employee Table:
-+-------------+------------+
-| employee_id | team_id    |
-+-------------+------------+
-|     1       |     8      |
-|     2       |     8      |
-|     3       |     8      |
-|     4       |     7      |
-|     5       |     9      |
-|     6       |     9      |
-+-------------+------------+
-Result table:
-+-------------+------------+
-| employee_id | team_size  |
-+-------------+------------+
-|     1       |     3      |
-|     2       |     3      |
-|     3       |     3      |
-|     4       |     1      |
-|     5       |     2      |
-|     6       |     2      |
-+-------------+------------+
-Employees with Id 1,2,3 are part of a team with team_id = 8.
-Employees with Id 4 is part of a team with team_id = 7.
-Employees with Id 5,6 are part of a team with team_id = 9.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/find-the-team-size/mysql_schemas.sql b/problems/find-the-team-size/mysql_schemas.sql
deleted file mode 100644
index bd2dc77d2..000000000
--- a/problems/find-the-team-size/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Employee (employee_id int, team_id int);
-Truncate table Employee;
-insert into Employee (employee_id, team_id) values ('1', '8');
-insert into Employee (employee_id, team_id) values ('2', '8');
-insert into Employee (employee_id, team_id) values ('3', '8');
-insert into Employee (employee_id, team_id) values ('4', '7');
-insert into Employee (employee_id, team_id) values ('5', '9');
-insert into Employee (employee_id, team_id) values ('6', '9');
diff --git a/problems/find-the-town-judge/README.md b/problems/find-the-town-judge/README.md
deleted file mode 100644
index ff1d47922..000000000
--- a/problems/find-the-town-judge/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-squareful-arrays "Number of Squareful Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-binary-tree-ii "Maximum Binary Tree II")
-
-## [997. Find the Town Judge (Easy)](https://leetcode.com/problems/find-the-town-judge "找到小镇的法官")
-
-<p>In a town, there are <code>n</code> people labeled from <code>1</code> to <code>n</code>. There is a rumor that one of these people is secretly the town judge.</p>
-
-<p>If the town judge exists, then:</p>
-
-<ol>
-	<li>The town judge trusts nobody.</li>
-	<li>Everybody (except for the town judge) trusts the town judge.</li>
-	<li>There is exactly one person that satisfies properties <strong>1</strong> and <strong>2</strong>.</li>
-</ol>
-
-<p>You are given an array <code>trust</code> where <code>trust[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> representing that the person labeled <code>a<sub>i</sub></code> trusts the person labeled <code>b<sub>i</sub></code>.</p>
-
-<p>Return <em>the label of the town judge if the town judge exists and can be identified, or return </em><code>-1</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, trust = [[1,2]]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, trust = [[1,3],[2,3]]
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, trust = [[1,3],[2,3],[3,1]]
-<strong>Output:</strong> -1
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, trust = [[1,2],[2,3]]
-<strong>Output:</strong> -1
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, trust = [[1,3],[1,4],[2,3],[2,4],[4,3]]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>0 &lt;= trust.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>trust[i].length == 2</code></li>
-	<li>All the pairs of <code>trust</code> are <strong>unique</strong>.</li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-	<li><code>1 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [Find the Celebrity](../find-the-celebrity) (Medium)
diff --git a/problems/find-the-town-judge/find_the_town_judge.go b/problems/find-the-town-judge/find_the_town_judge.go
deleted file mode 100644
index 012ed150a..000000000
--- a/problems/find-the-town-judge/find_the_town_judge.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem997
-
-func findJudge(N int, trust [][]int) int {
-	ans, count := 1, make([]int, N+1)
-	for _, t := range trust {
-		count[t[0]] = N
-		count[t[1]]++
-		if count[t[1]] == N-1 {
-			ans = t[1]
-		}
-		if ans == t[0] {
-			ans = -1
-		}
-	}
-	return ans
-}
diff --git a/problems/find-the-town-judge/find_the_town_judge_test.go b/problems/find-the-town-judge/find_the_town_judge_test.go
deleted file mode 100644
index 73eca79a9..000000000
--- a/problems/find-the-town-judge/find_the_town_judge_test.go
+++ /dev/null
@@ -1,68 +0,0 @@
-package problem997
-
-import "testing"
-
-type testType struct {
-	N     int
-	trust [][]int
-	want  int
-}
-
-func TestFindJudge(t *testing.T) {
-	tests := [...]testType{
-		{
-			N: 2,
-			trust: [][]int{
-				{1, 2},
-			},
-			want: 2,
-		},
-		{
-			N: 3,
-			trust: [][]int{
-				{1, 3},
-				{2, 3},
-			},
-			want: 3,
-		},
-		{
-			N: 3,
-			trust: [][]int{
-				{1, 3},
-				{2, 3},
-				{3, 1},
-			},
-			want: -1,
-		},
-		{
-			N: 3,
-			trust: [][]int{
-				{1, 2},
-				{2, 3},
-			},
-			want: -1,
-		},
-		{
-			N: 4,
-			trust: [][]int{
-				{1, 3},
-				{1, 4},
-				{2, 3},
-				{2, 4},
-				{4, 3},
-			},
-			want: 3,
-		},
-		{
-			N:     1,
-			trust: [][]int{},
-			want:  1,
-		},
-	}
-	for _, tt := range tests {
-		got := findJudge(tt.N, tt.trust)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.N, tt.trust, got, tt.want)
-		}
-	}
-}
diff --git a/problems/find-the-winner-of-an-array-game/README.md b/problems/find-the-winner-of-an-array-game/README.md
deleted file mode 100644
index 70bb38ceb..000000000
--- a/problems/find-the-winner-of-an-array-game/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-good-triplets "Count Good Triplets")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-swaps-to-arrange-a-binary-grid "Minimum Swaps to Arrange a Binary Grid")
-
-## [1535. Find the Winner of an Array Game (Medium)](https://leetcode.com/problems/find-the-winner-of-an-array-game "找出数组游戏的赢家")
-
-<p>Given an integer array <code>arr</code> of <strong>distinct</strong> integers and an integer <code>k</code>.</p>
-
-<p>A game will be played between the first two elements of the array (i.e. <code>arr[0]</code> and <code>arr[1]</code>). In each round of the game, we compare <code>arr[0]</code> with <code>arr[1]</code>, the larger integer wins and remains at position <code>0</code>, and the smaller integer moves to the end of the array. The game ends when an integer wins <code>k</code> consecutive rounds.</p>
-
-<p>Return <em>the integer which will win the game</em>.</p>
-
-<p>It is <strong>guaranteed</strong> that there will be a winner of the game.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,1,3,5,4,6,7], k = 2
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Let&#39;s see the rounds of the game:
-Round |       arr       | winner | win_count
-  1   | [2,1,3,5,4,6,7] | 2      | 1
-  2   | [2,3,5,4,6,7,1] | 3      | 1
-  3   | [3,5,4,6,7,1,2] | 5      | 1
-  4   | [5,4,6,7,1,2,3] | 5      | 2
-So we can see that 4 rounds will be played and 5 is the winner because it wins 2 consecutive games.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,2,1], k = 10
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 3 will win the first 10 rounds consecutively.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>arr</code> contains <strong>distinct</strong> integers.</li>
-	<li><code>1 &lt;= k &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If k ≥ arr.length return the max element of the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If k < arr.length simulate the game until a number wins k consecutive games.
-</details>
diff --git a/problems/find-the-winner-of-the-circular-game/README.md b/problems/find-the-winner-of-the-circular-game/README.md
deleted file mode 100644
index f697c1c36..000000000
--- a/problems/find-the-winner-of-the-circular-game/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sign-of-the-product-of-an-array "Sign of the Product of an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-sideway-jumps "Minimum Sideway Jumps")
-
-## [1823. Find the Winner of the Circular Game (Medium)](https://leetcode.com/problems/find-the-winner-of-the-circular-game "找出游戏的获胜者")
-
-<p>There are <code>n</code> friends that are playing a game. The friends are sitting in a circle and are numbered from <code>1</code> to <code>n</code> in <strong>clockwise order</strong>. More formally, moving clockwise from the <code>i<sup>th</sup></code> friend brings you to the <code>(i+1)<sup>th</sup></code> friend for <code>1 &lt;= i &lt; n</code>, and moving clockwise from the <code>n<sup>th</sup></code> friend brings you to the <code>1<sup>st</sup></code> friend.</p>
-
-<p>The rules of the game are as follows:</p>
-
-<ol>
-	<li><strong>Start</strong> at the <code>1<sup>st</sup></code> friend.</li>
-	<li>Count the next <code>k</code> friends in the clockwise direction <strong>including</strong> the friend you started at. The counting wraps around the circle and may count some friends more than once.</li>
-	<li>The last friend you counted leaves the circle and loses the game.</li>
-	<li>If there is still more than one friend in the circle, go back to step <code>2</code> <strong>starting</strong> from the friend <strong>immediately clockwise</strong> of the friend who just lost and repeat.</li>
-	<li>Else, the last friend in the circle wins the game.</li>
-</ol>
-
-<p>Given the number of friends, <code>n</code>, and an integer <code>k</code>, return <em>the winner of the game</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/25/ic234-q2-ex11.png" style="width: 500px; height: 345px;" />
-<pre>
-<strong>Input:</strong> n = 5, k = 2
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Here are the steps of the game:
-1) Start at friend 1.
-2) Count 2 friends clockwise, which are friends 1 and 2.
-3) Friend 2 leaves the circle. Next start is friend 3.
-4) Count 2 friends clockwise, which are friends 3 and 4.
-5) Friend 4 leaves the circle. Next start is friend 5.
-6) Count 2 friends clockwise, which are friends 5 and 1.
-7) Friend 1 leaves the circle. Next start is friend 3.
-8) Count 2 friends clockwise, which are friends 3 and 5.
-9) Friend 5 leaves the circle. Only friend 3 is left, so they are the winner.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6, k = 5
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The friends leave in this order: 5, 4, 6, 2, 3. The winner is friend 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= n &lt;= 500</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Maintain in a circular list the people who are still in the circle and the current person you are standing at.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-In each turn, count k people and remove the last person from the list.
-</details>
diff --git a/problems/find-total-time-spent-by-each-employee/README.md b/problems/find-total-time-spent-by-each-employee/README.md
deleted file mode 100644
index 280619629..000000000
--- a/problems/find-total-time-spent-by-each-employee/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-distance-in-a-binary-tree "Find Distance in a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-balls-in-a-box "Maximum Number of Balls in a Box")
-
-## [1741. Find Total Time Spent by Each Employee (Easy)](https://leetcode.com/problems/find-total-time-spent-by-each-employee "查找每个员工花费的总时间")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/find-total-time-spent-by-each-employee/mysql_schemas.sql b/problems/find-total-time-spent-by-each-employee/mysql_schemas.sql
deleted file mode 100644
index 1431641c1..000000000
--- a/problems/find-total-time-spent-by-each-employee/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Employees(emp_id int, event_day date, in_time int, out_time int);
-Truncate table Employees;
-insert into Employees (emp_id, event_day, in_time, out_time) values ('1', '2020-11-28', '4', '32');
-insert into Employees (emp_id, event_day, in_time, out_time) values ('1', '2020-11-28', '55', '200');
-insert into Employees (emp_id, event_day, in_time, out_time) values ('1', '2020-12-3', '1', '42');
-insert into Employees (emp_id, event_day, in_time, out_time) values ('2', '2020-11-28', '3', '33');
-insert into Employees (emp_id, event_day, in_time, out_time) values ('2', '2020-12-9', '47', '74');
diff --git a/problems/find-two-non-overlapping-sub-arrays-each-with-target-sum/README.md b/problems/find-two-non-overlapping-sub-arrays-each-with-target-sum/README.md
deleted file mode 100644
index 8f35b94cf..000000000
--- a/problems/find-two-non-overlapping-sub-arrays-each-with-target-sum/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subrectangle-queries "Subrectangle Queries")
-　　　　　　　　　　　　　　　　
-[Next >](../allocate-mailboxes "Allocate Mailboxes")
-
-## [1477. Find Two Non-overlapping Sub-arrays Each With Target Sum (Medium)](https://leetcode.com/problems/find-two-non-overlapping-sub-arrays-each-with-target-sum "找两个和为目标值且不重叠的子数组")
-
-<p>You are given an array of integers <code>arr</code> and an integer <code>target</code>.</p>
-
-<p>You have to find <strong>two non-overlapping sub-arrays</strong> of <code>arr</code> each with a sum equal <code>target</code>. There can be multiple answers so you have to find an answer where the sum of the lengths of the two sub-arrays is <strong>minimum</strong>.</p>
-
-<p>Return <em>the minimum sum of the lengths</em> of the two required sub-arrays, or return <code>-1</code> if you cannot find such two sub-arrays.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,2,2,4,3], target = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Only two sub-arrays have sum = 3 ([3] and [3]). The sum of their lengths is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [7,3,4,7], target = 7
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Although we have three non-overlapping sub-arrays of sum = 7 ([7], [3,4] and [7]), but we will choose the first and third sub-arrays as the sum of their lengths is 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,3,2,6,2,3,4], target = 6
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> We have only one sub-array of sum = 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 1000</code></li>
-	<li><code>1 &lt;= target &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's create two arrays prefix and suffix where prefix[i] is the minimum length of sub-array ends before i and has sum = k, suffix[i] is the minimum length of sub-array starting at or after i and has sum = k.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The answer we are searching for is min(prefix[i] + suffix[i]) for all values of i from 0 to n-1 where n == arr.length.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If you are still stuck with how to build prefix and suffix, you can store for each index i the length of the sub-array starts at i and has sum = k or infinity otherwise, and you can use it to build both prefix and suffix.
-</details>
diff --git a/problems/find-unique-binary-string/README.md b/problems/find-unique-binary-string/README.md
deleted file mode 100644
index 986125758..000000000
--- a/problems/find-unique-binary-string/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-greatest-common-divisor-of-array "Find Greatest Common Divisor of Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimize-the-difference-between-target-and-chosen-elements "Minimize the Difference Between Target and Chosen Elements")
-
-## [1980. Find Unique Binary String (Medium)](https://leetcode.com/problems/find-unique-binary-string "找出不同的二进制字符串")
-
-<p>Given an array of strings <code>nums</code> containing <code>n</code> <strong>unique</strong> binary strings each of length <code>n</code>, return <em>a binary string of length </em><code>n</code><em> that <strong>does not appear</strong> in </em><code>nums</code><em>. If there are multiple answers, you may return <strong>any</strong> of them</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [&quot;01&quot;,&quot;10&quot;]
-<strong>Output:</strong> &quot;11&quot;
-<strong>Explanation:</strong> &quot;11&quot; does not appear in nums. &quot;00&quot; would also be correct.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [&quot;00&quot;,&quot;01&quot;]
-<strong>Output:</strong> &quot;11&quot;
-<strong>Explanation:</strong> &quot;11&quot; does not appear in nums. &quot;10&quot; would also be correct.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [&quot;111&quot;,&quot;011&quot;,&quot;001&quot;]
-<strong>Output:</strong> &quot;101&quot;
-<strong>Explanation:</strong> &quot;101&quot; does not appear in nums. &quot;000&quot;, &quot;010&quot;, &quot;100&quot;, and &quot;110&quot; would also be correct.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 16</code></li>
-	<li><code>nums[i].length == n</code></li>
-	<li><code>nums[i] </code>is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-	<li>All the strings of <code>nums</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can convert the given strings into base 10 integers.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use recursion to generate all possible strings?
-</details>
diff --git a/problems/find-users-with-valid-e-mails/README.md b/problems/find-users-with-valid-e-mails/README.md
deleted file mode 100644
index d28cde732..000000000
--- a/problems/find-users-with-valid-e-mails/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../move-sub-tree-of-n-ary-tree "Move Sub-Tree of N-Ary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../water-bottles "Water Bottles")
-
-## [1517. Find Users With Valid E-Mails (Easy)](https://leetcode.com/problems/find-users-with-valid-e-mails "查找拥有有效邮箱的用户")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/find-users-with-valid-e-mails/mysql_schemas.sql b/problems/find-users-with-valid-e-mails/mysql_schemas.sql
deleted file mode 100644
index a9fe9964d..000000000
--- a/problems/find-users-with-valid-e-mails/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Users (user_id int, name varchar(30), mail varchar(50));
-Truncate table Users;
-insert into Users (user_id, name, mail) values ('1', 'Winston', 'winston@leetcode.com');
-insert into Users (user_id, name, mail) values ('2', 'Jonathan', 'jonathanisgreat');
-insert into Users (user_id, name, mail) values ('3', 'Annabelle', 'bella-@leetcode.com');
-insert into Users (user_id, name, mail) values ('4', 'Sally', 'sally.come@leetcode.com');
-insert into Users (user_id, name, mail) values ('5', 'Marwan', 'quarz#2020@leetcode.com');
-insert into Users (user_id, name, mail) values ('6', 'David', 'david69@gmail.com');
-insert into Users (user_id, name, mail) values ('7', 'Shapiro', '.shapo@leetcode.com');
diff --git a/problems/find-valid-matrix-given-row-and-column-sums/README.md b/problems/find-valid-matrix-given-row-and-column-sums/README.md
deleted file mode 100644
index 1ca194f17..000000000
--- a/problems/find-valid-matrix-given-row-and-column-sums/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../alert-using-same-key-card-three-or-more-times-in-a-one-hour-period "Alert Using Same Key-Card Three or More Times in a One Hour Period")
-　　　　　　　　　　　　　　　　
-[Next >](../find-servers-that-handled-most-number-of-requests "Find Servers That Handled Most Number of Requests")
-
-## [1605. Find Valid Matrix Given Row and Column Sums (Medium)](https://leetcode.com/problems/find-valid-matrix-given-row-and-column-sums "给定行和列的和求可行矩阵")
-
-<p>You are given two arrays <code>rowSum</code> and <code>colSum</code> of non-negative integers where <code>rowSum[i]</code> is the sum of the elements in the <code>i<sup>th</sup></code> row and <code>colSum[j]</code> is the sum of the elements of the <code>j<sup>th</sup></code> column of a 2D matrix. In other words, you do not know the elements of the matrix, but you do know the sums of each row and column.</p>
-
-<p>Find any matrix of <strong>non-negative</strong> integers of size <code>rowSum.length x colSum.length</code> that satisfies the <code>rowSum</code> and <code>colSum</code> requirements.</p>
-
-<p>Return <em>a 2D array representing <strong>any</strong> matrix that fulfills the requirements</em>. It&#39;s guaranteed that <strong>at least one </strong>matrix that fulfills the requirements exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rowSum = [3,8], colSum = [4,7]
-<strong>Output:</strong> [[3,0],
-         [1,7]]
-<strong>Explanation:</strong> 
-0<sup>th</sup> row: 3 + 0 = 3 == rowSum[0]
-1<sup>st</sup> row: 1 + 7 = 8 == rowSum[1]
-0<sup>th</sup> column: 3 + 1 = 4 == colSum[0]
-1<sup>st</sup> column: 0 + 7 = 7 == colSum[1]
-The row and column sums match, and all matrix elements are non-negative.
-Another possible matrix is: [[1,2],
-                             [3,5]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rowSum = [5,7,10], colSum = [8,6,8]
-<strong>Output:</strong> [[0,5,0],
-         [6,1,0],
-         [2,0,8]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rowSum.length, colSum.length &lt;= 500</code></li>
-	<li><code>0 &lt;= rowSum[i], colSum[i] &lt;= 10<sup>8</sup></code></li>
-	<li><code>sum(rows) == sum(columns)</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the smallest rowSum or colSum, and let it be x. Place that number in the grid, and subtract x from rowSum and colSum. Continue until all the sums are satisfied.
-</details>
diff --git a/problems/find-winner-on-a-tic-tac-toe-game/README.md b/problems/find-winner-on-a-tic-tac-toe-game/README.md
deleted file mode 100644
index b92f461f3..000000000
--- a/problems/find-winner-on-a-tic-tac-toe-game/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ships-in-a-rectangle "Number of Ships in a Rectangle")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-burgers-with-no-waste-of-ingredients "Number of Burgers with No Waste of Ingredients")
-
-## [1275. Find Winner on a Tic Tac Toe Game (Easy)](https://leetcode.com/problems/find-winner-on-a-tic-tac-toe-game "找出井字棋的获胜者")
-
-<p><strong>Tic-tac-toe</strong> is played by two players <code>A</code> and <code>B</code> on a <code>3 x 3</code> grid. The rules of Tic-Tac-Toe are:</p>
-
-<ul>
-	<li>Players take turns placing characters into empty squares <code>&#39; &#39;</code>.</li>
-	<li>The first player <code>A</code> always places <code>&#39;X&#39;</code> characters, while the second player <code>B</code> always places <code>&#39;O&#39;</code> characters.</li>
-	<li><code>&#39;X&#39;</code> and <code>&#39;O&#39;</code> characters are always placed into empty squares, never on filled ones.</li>
-	<li>The game ends when there are <strong>three</strong> of the same (non-empty) character filling any row, column, or diagonal.</li>
-	<li>The game also ends if all squares are non-empty.</li>
-	<li>No more moves can be played if the game is over.</li>
-</ul>
-
-<p>Given a 2D integer array <code>moves</code> where <code>moves[i] = [row<sub>i</sub>, col<sub>i</sub>]</code> indicates that the <code>i<sup>th</sup></code> move will be played on <code>grid[row<sub>i</sub>][col<sub>i</sub>]</code>. return <em>the winner of the game if it exists</em> (<code>A</code> or <code>B</code>). In case the game ends in a draw return <code>&quot;Draw&quot;</code>. If there are still movements to play return <code>&quot;Pending&quot;</code>.</p>
-
-<p>You can assume that <code>moves</code> is valid (i.e., it follows the rules of <strong>Tic-Tac-Toe</strong>), the grid is initially empty, and <code>A</code> will play first.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/22/xo1-grid.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> moves = [[0,0],[2,0],[1,1],[2,1],[2,2]]
-<strong>Output:</strong> &quot;A&quot;
-<strong>Explanation:</strong> A wins, they always play first.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/22/xo2-grid.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> moves = [[0,0],[1,1],[0,1],[0,2],[1,0],[2,0]]
-<strong>Output:</strong> &quot;B&quot;
-<strong>Explanation:</strong> B wins.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/22/xo3-grid.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> moves = [[0,0],[1,1],[2,0],[1,0],[1,2],[2,1],[0,1],[0,2],[2,2]]
-<strong>Output:</strong> &quot;Draw&quot;
-<strong>Explanation:</strong> The game ends in a draw since there are no moves to make.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= moves.length &lt;= 9</code></li>
-	<li><code>moves[i].length == 2</code></li>
-	<li><code>0 &lt;= row<sub>i</sub>, col<sub>i</sub> &lt;= 2</code></li>
-	<li>There are no repeated elements on <code>moves</code>.</li>
-	<li><code>moves</code> follow the rules of tic tac toe.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-It's straightforward to check if A or B won or not, check for each row/column/diag if all the three are the same.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Then if no one wins, the game is a draw iff the board is full, i.e. moves.length = 9 otherwise is pending.
-</details>
diff --git a/problems/find-words-that-can-be-formed-by-characters/README.md b/problems/find-words-that-can-be-formed-by-characters/README.md
deleted file mode 100644
index 86c08abca..000000000
--- a/problems/find-words-that-can-be-formed-by-characters/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../market-analysis-ii "Market Analysis II")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-level-sum-of-a-binary-tree "Maximum Level Sum of a Binary Tree")
-
-## [1160. Find Words That Can Be Formed by Characters (Easy)](https://leetcode.com/problems/find-words-that-can-be-formed-by-characters "拼写单词")
-
-<p>You are given an array of strings <code>words</code> and a string <code>chars</code>.</p>
-
-<p>A string is <strong>good</strong> if it can be formed by characters from chars (each character can only be used once).</p>
-
-<p>Return <em>the sum of lengths of all good strings in words</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;cat&quot;,&quot;bt&quot;,&quot;hat&quot;,&quot;tree&quot;], chars = &quot;atach&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The strings that can be formed are &quot;cat&quot; and &quot;hat&quot; so the answer is 3 + 3 = 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;hello&quot;,&quot;world&quot;,&quot;leetcode&quot;], chars = &quot;welldonehoneyr&quot;
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> The strings that can be formed are &quot;hello&quot; and &quot;world&quot; so the answer is 5 + 5 = 10.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= words[i].length, chars.length &lt;= 100</code></li>
-	<li><code>words[i]</code> and <code>chars</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Solve the problem for each string in <code>words</code> independently.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Now try to think in frequency of letters.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Count how many times each character occurs in string <code>chars</code>.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-To form a string using characters from <code>chars</code>, the frequency of each character in <code>chars</code> must be greater than or equal the frequency of that character in the string to be formed.
-</details>
diff --git a/problems/find-xor-sum-of-all-pairs-bitwise-and/README.md b/problems/find-xor-sum-of-all-pairs-bitwise-and/README.md
deleted file mode 100644
index 188930335..000000000
--- a/problems/find-xor-sum-of-all-pairs-bitwise-and/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../single-threaded-cpu "Single-Threaded CPU")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-duplicates-from-an-unsorted-linked-list "Remove Duplicates From an Unsorted Linked List")
-
-## [1835. Find XOR Sum of All Pairs Bitwise AND (Hard)](https://leetcode.com/problems/find-xor-sum-of-all-pairs-bitwise-and "所有数对按位与结果的异或和")
-
-<p>The <strong>XOR sum</strong> of a list is the bitwise <code>XOR</code> of all its elements. If the list only contains one element, then its <strong>XOR sum</strong> will be equal to this element.</p>
-
-<ul>
-	<li>For example, the <strong>XOR sum</strong> of <code>[1,2,3,4]</code> is equal to <code>1 XOR 2 XOR 3 XOR 4 = 4</code>, and the <strong>XOR sum</strong> of <code>[3]</code> is equal to <code>3</code>.</li>
-</ul>
-
-<p>You are given two <strong>0-indexed</strong> arrays <code>arr1</code> and <code>arr2</code> that consist only of non-negative integers.</p>
-
-<p>Consider the list containing the result of <code>arr1[i] AND arr2[j]</code> (bitwise <code>AND</code>) for every <code>(i, j)</code> pair where <code>0 &lt;= i &lt; arr1.length</code> and <code>0 &lt;= j &lt; arr2.length</code>.</p>
-
-<p>Return <em>the <strong>XOR sum</strong> of the aforementioned list</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [1,2,3], arr2 = [6,5]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The list = [1 AND 6, 1 AND 5, 2 AND 6, 2 AND 5, 3 AND 6, 3 AND 5] = [0,1,2,0,2,1].
-The XOR sum = 0 XOR 1 XOR 2 XOR 0 XOR 2 XOR 1 = 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [12], arr2 = [4]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The list = [12 AND 4] = [4]. The XOR sum = 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr1.length, arr2.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= arr1[i], arr2[j] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think about (a&b) ^ (a&c). Can you simplify this expression?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-It is equal to a&(b^c). Then, (arr1[i]&arr2[0])^(arr1[i]&arr2[1]).. = arr1[i]&(arr2[0]^arr2[1]^arr[2]...).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Let arr2XorSum = (arr2[0]^arr2[1]^arr2[2]...), arr1XorSum = (arr1[0]^arr1[1]^arr1[2]...) so the final answer is (arr2XorSum&arr1[0]) ^ (arr2XorSum&arr1[1]) ^ (arr2XorSum&arr1[2]) ^ ... = arr2XorSum & arr1XorSum.
-</details>
diff --git a/problems/finding-3-digit-even-numbers/README.md b/problems/finding-3-digit-even-numbers/README.md
deleted file mode 100644
index b3b7cc928..000000000
--- a/problems/finding-3-digit-even-numbers/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-reach-city-with-discounts "Minimum Cost to Reach City With Discounts")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-the-middle-node-of-a-linked-list "Delete the Middle Node of a Linked List")
-
-## [2094. Finding 3-Digit Even Numbers (Easy)](https://leetcode.com/problems/finding-3-digit-even-numbers "找出 3 位偶数")
-
-<p>You are given an integer array <code>digits</code>, where each element is a digit. The array may contain duplicates.</p>
-
-<p>You need to find <strong>all</strong> the <strong>unique</strong> integers that follow the given requirements:</p>
-
-<ul>
-	<li>The integer consists of the <strong>concatenation</strong> of <strong>three</strong> elements from <code>digits</code> in <strong>any</strong> arbitrary order.</li>
-	<li>The integer does not have <strong>leading zeros</strong>.</li>
-	<li>The integer is <strong>even</strong>.</li>
-</ul>
-
-<p>For example, if the given <code>digits</code> were <code>[1, 2, 3]</code>, integers <code>132</code> and <code>312</code> follow the requirements.</p>
-
-<p>Return <em>a <strong>sorted</strong> array of the unique integers.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [2,1,3,0]
-<strong>Output:</strong> [102,120,130,132,210,230,302,310,312,320]
-<strong>Explanation:</strong> All the possible integers that follow the requirements are in the output array. 
-Notice that there are no <strong>odd</strong> integers or integers with <strong>leading zeros</strong>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [2,2,8,8,2]
-<strong>Output:</strong> [222,228,282,288,822,828,882]
-<strong>Explanation:</strong> The same digit can be used as many times as it appears in digits. 
-In this example, the digit 8 is used twice each time in 288, 828, and 882. 
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [3,7,5]
-<strong>Output:</strong> []
-<strong>Explanation:</strong> No <strong>even</strong> integers can be formed using the given digits.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= digits.length &lt;= 100</code></li>
-	<li><code>0 &lt;= digits[i] &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The range of possible answers includes all even numbers between 100 and 999 inclusive. Could you check each possible answer to see if it could be formed from the digits in the array?
-</details>
diff --git a/problems/finding-mk-average/README.md b/problems/finding-mk-average/README.md
deleted file mode 100644
index 8986cc95c..000000000
--- a/problems/finding-mk-average/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-sideway-jumps "Minimum Sideway Jumps")
-　　　　　　　　　　　　　　　　
-[Next >](../faulty-sensor "Faulty Sensor")
-
-## [1825. Finding MK Average (Hard)](https://leetcode.com/problems/finding-mk-average "求出 MK 平均值")
-
-<p>You are given two integers, <code>m</code> and <code>k</code>, and a stream of integers. You are tasked to implement a data structure that calculates the <strong>MKAverage</strong> for the stream.</p>
-
-<p>The <strong>MKAverage</strong> can be calculated using these steps:</p>
-
-<ol>
-	<li>If the number of the elements in the stream is less than <code>m</code> you should consider the <strong>MKAverage</strong> to be <code>-1</code>. Otherwise, copy the last <code>m</code> elements of the stream to a separate container.</li>
-	<li>Remove the smallest <code>k</code> elements and the largest <code>k</code> elements from the container.</li>
-	<li>Calculate the average value for the rest of the elements <strong>rounded down to the nearest integer</strong>.</li>
-</ol>
-
-<p>Implement the <code>MKAverage</code> class:</p>
-
-<ul>
-	<li><code>MKAverage(int m, int k)</code> Initializes the <strong>MKAverage</strong> object with an empty stream and the two integers <code>m</code> and <code>k</code>.</li>
-	<li><code>void addElement(int num)</code> Inserts a new element <code>num</code> into the stream.</li>
-	<li><code>int calculateMKAverage()</code> Calculates and returns the <strong>MKAverage</strong> for the current stream <strong>rounded down to the nearest integer</strong>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MKAverage&quot;, &quot;addElement&quot;, &quot;addElement&quot;, &quot;calculateMKAverage&quot;, &quot;addElement&quot;, &quot;calculateMKAverage&quot;, &quot;addElement&quot;, &quot;addElement&quot;, &quot;addElement&quot;, &quot;calculateMKAverage&quot;]
-[[3, 1], [3], [1], [], [10], [], [5], [5], [5], []]
-<strong>Output</strong>
-[null, null, null, -1, null, 3, null, null, null, 5]
-
-<strong>Explanation</strong>
-MKAverage obj = new MKAverage(3, 1); 
-obj.addElement(3);        // current elements are [3]
-obj.addElement(1);        // current elements are [3,1]
-obj.calculateMKAverage(); // return -1, because m = 3 and only 2 elements exist.
-obj.addElement(10);       // current elements are [3,1,10]
-obj.calculateMKAverage(); // The last 3 elements are [3,1,10].
-                          // After removing smallest and largest 1 element the container will be <code>[3].
-                          // The average of [3] equals 3/1 = 3, return 3
-obj.addElement(5);        // current elements are [3,1,10,5]
-obj.addElement(5);        // current elements are [3,1,10,5,5]
-obj.addElement(5);        // current elements are [3,1,10,5,5,5]
-obj.calculateMKAverage(); // The last 3 elements are [5,5,5].
-                          // After removing smallest and largest 1 element the container will be <code>[5].
-                          // The average of [5] equals 5/1 = 5, return 5
-</code></code></pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= m &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= k*2 &lt; m</code></li>
-	<li><code>1 &lt;= num &lt;= 10<sup>5</sup></code></li>
-	<li>At most <code>10<sup>5</sup></code> calls will be made to <code>addElement</code> and <code>calculateMKAverage</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [Find Median from Data Stream](../find-median-from-data-stream) (Hard)
-  1. [Kth Largest Element in a Stream](../kth-largest-element-in-a-stream) (Easy)
-  1. [Sequentially Ordinal Rank Tracker](../sequentially-ordinal-rank-tracker) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-At each query, try to save and update the sum of the elements needed to calculate MKAverage.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can use BSTs for fast insertion and deletion of the elements.
-</details>
diff --git a/problems/finding-pairs-with-a-certain-sum/README.md b/problems/finding-pairs-with-a-certain-sum/README.md
deleted file mode 100644
index 618963a92..000000000
--- a/problems/finding-pairs-with-a-certain-sum/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-swaps-to-make-the-binary-string-alternating "Minimum Number of Swaps to Make the Binary String Alternating")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-rearrange-sticks-with-k-sticks-visible "Number of Ways to Rearrange Sticks With K Sticks Visible")
-
-## [1865. Finding Pairs With a Certain Sum (Medium)](https://leetcode.com/problems/finding-pairs-with-a-certain-sum "找出和为指定值的下标对")
-
-<p>You are given two integer arrays <code>nums1</code> and <code>nums2</code>. You are tasked to implement a data structure that supports queries of two types:</p>
-
-<ol>
-	<li><strong>Add</strong> a positive integer to an element of a given index in the array <code>nums2</code>.</li>
-	<li><strong>Count</strong> the number of pairs <code>(i, j)</code> such that <code>nums1[i] + nums2[j]</code> equals a given value (<code>0 &lt;= i &lt; nums1.length</code> and <code>0 &lt;= j &lt; nums2.length</code>).</li>
-</ol>
-
-<p>Implement the <code>FindSumPairs</code> class:</p>
-
-<ul>
-	<li><code>FindSumPairs(int[] nums1, int[] nums2)</code> Initializes the <code>FindSumPairs</code> object with two integer arrays <code>nums1</code> and <code>nums2</code>.</li>
-	<li><code>void add(int index, int val)</code> Adds <code>val</code> to <code>nums2[index]</code>, i.e., apply <code>nums2[index] += val</code>.</li>
-	<li><code>int count(int tot)</code> Returns the number of pairs <code>(i, j)</code> such that <code>nums1[i] + nums2[j] == tot</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;FindSumPairs&quot;, &quot;count&quot;, &quot;add&quot;, &quot;count&quot;, &quot;count&quot;, &quot;add&quot;, &quot;add&quot;, &quot;count&quot;]
-[[[1, 1, 2, 2, 2, 3], [1, 4, 5, 2, 5, 4]], [7], [3, 2], [8], [4], [0, 1], [1, 1], [7]]
-<strong>Output</strong>
-[null, 8, null, 2, 1, null, null, 11]
-
-<strong>Explanation</strong>
-FindSumPairs findSumPairs = new FindSumPairs([1, 1, 2, 2, 2, 3], [1, 4, 5, 2, 5, 4]);
-findSumPairs.count(7);  // return 8; pairs (2,2), (3,2), (4,2), (2,4), (3,4), (4,4) make 2 + 5 and pairs (5,1), (5,5) make 3 + 4
-findSumPairs.add(3, 2); // now nums2 = [1,4,5,<strong><u>4</u></strong><code>,5,4</code>]
-findSumPairs.count(8);  // return 2; pairs (5,2), (5,4) make 3 + 5
-findSumPairs.count(4);  // return 1; pair (5,0) makes 3 + 1
-findSumPairs.add(0, 1); // now nums2 = [<strong><u><code>2</code></u></strong>,4,5,4<code>,5,4</code>]
-findSumPairs.add(1, 1); // now nums2 = [<code>2</code>,<strong><u>5</u></strong>,5,4<code>,5,4</code>]
-findSumPairs.count(7);  // return 11; pairs (2,1), (2,2), (2,4), (3,1), (3,2), (3,4), (4,1), (4,2), (4,4) make 2 + 5 and pairs (5,3), (5,5) make 3 + 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums2.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums1[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= nums2[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= index &lt; nums2.length</code></li>
-	<li><code>1 &lt;= val &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= tot &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>1000</code> calls are made to <code>add</code> and <code>count</code> <strong>each</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Similar Questions
-  1. [Count Number of Pairs With Absolute Difference K](../count-number-of-pairs-with-absolute-difference-k) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The length of nums1 is small in comparison to that of nums2
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If we iterate over elements of nums1 we just need to find the count of tot - element for all elements in nums1
-</details>
diff --git a/problems/finding-the-users-active-minutes/README.md b/problems/finding-the-users-active-minutes/README.md
deleted file mode 100644
index 4b7acd96b..000000000
--- a/problems/finding-the-users-active-minutes/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../truncate-sentence "Truncate Sentence")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-absolute-sum-difference "Minimum Absolute Sum Difference")
-
-## [1817. Finding the Users Active Minutes (Medium)](https://leetcode.com/problems/finding-the-users-active-minutes "查找用户活跃分钟数")
-
-<p>You are given the logs for users&#39; actions on LeetCode, and an integer <code>k</code>. The logs are represented by a 2D integer array <code>logs</code> where each <code>logs[i] = [ID<sub>i</sub>, time<sub>i</sub>]</code> indicates that the user with <code>ID<sub>i</sub></code> performed an action at the minute <code>time<sub>i</sub></code>.</p>
-
-<p><strong>Multiple users</strong> can perform actions simultaneously, and a single user can perform <strong>multiple actions</strong> in the same minute.</p>
-
-<p>The <strong>user active minutes (UAM)</strong> for a given user is defined as the <strong>number of unique minutes</strong> in which the user performed an action on LeetCode. A minute can only be counted once, even if multiple actions occur during it.</p>
-
-<p>You are to calculate a <strong>1-indexed</strong> array <code>answer</code> of size <code>k</code> such that, for each <code>j</code> (<code>1 &lt;= j &lt;= k</code>), <code>answer[j]</code> is the <strong>number of users</strong> whose <strong>UAM</strong> equals <code>j</code>.</p>
-
-<p>Return <i>the array </i><code>answer</code><i> as described above</i>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> logs = [[0,5],[1,2],[0,2],[0,5],[1,3]], k = 5
-<strong>Output:</strong> [0,2,0,0,0]
-<strong>Explanation:</strong>
-The user with ID=0 performed actions at minutes 5, 2, and 5 again. Hence, they have a UAM of 2 (minute 5 is only counted once).
-The user with ID=1 performed actions at minutes 2 and 3. Hence, they have a UAM of 2.
-Since both users have a UAM of 2, answer[2] is 2, and the remaining answer[j] values are 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> logs = [[1,1],[2,2],[2,3]], k = 4
-<strong>Output:</strong> [1,1,0,0]
-<strong>Explanation:</strong>
-The user with ID=1 performed a single action at minute 1. Hence, they have a UAM of 1.
-The user with ID=2 performed actions at minutes 2 and 3. Hence, they have a UAM of 2.
-There is one user with a UAM of 1 and one with a UAM of 2.
-Hence, answer[1] = 1, answer[2] = 1, and the remaining values are 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= logs.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= ID<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= time<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-	<li><code>k</code> is in the range <code>[The maximum <strong>UAM</strong> for a user, 10<sup>5</sup>]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to find the number of different minutes when action happened for each user.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each user increase the value of the answer array index which matches the UAM for this user.
-</details>
diff --git a/problems/first-and-last-call-on-the-same-day/README.md b/problems/first-and-last-call-on-the-same-day/README.md
deleted file mode 100644
index c8755953e..000000000
--- a/problems/first-and-last-call-on-the-same-day/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-if-path-exists-in-graph "Find if Path Exists in Graph")
-　　　　　　　　　　　　　　　　
-[Next >](../count-nodes-equal-to-sum-of-descendants "Count Nodes Equal to Sum of Descendants")
-
-## [1972. First and Last Call On the Same Day (Hard)](https://leetcode.com/problems/first-and-last-call-on-the-same-day "同一天的第一个电话和最后一个电话")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/first-and-last-call-on-the-same-day/mysql_schemas.sql b/problems/first-and-last-call-on-the-same-day/mysql_schemas.sql
deleted file mode 100644
index ff703d10f..000000000
--- a/problems/first-and-last-call-on-the-same-day/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Calls (caller_id int, recipient_id int, call_time datetime);
-Truncate table Calls;
-insert into Calls (caller_id, recipient_id, call_time) values ('8', '4', '2021-08-24 17:46:07');
-insert into Calls (caller_id, recipient_id, call_time) values ('4', '8', '2021-08-24 19:57:13');
-insert into Calls (caller_id, recipient_id, call_time) values ('5', '1', '2021-08-11 05:28:44');
-insert into Calls (caller_id, recipient_id, call_time) values ('8', '3', '2021-08-17 04:04:15');
-insert into Calls (caller_id, recipient_id, call_time) values ('11', '3', '2021-08-17 13:07:00');
-insert into Calls (caller_id, recipient_id, call_time) values ('8', '11', '2021-08-17 22:22:22');
diff --git a/problems/first-bad-version/README.md b/problems/first-bad-version/README.md
deleted file mode 100644
index 8c880f141..000000000
--- a/problems/first-bad-version/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-celebrity "Find the Celebrity")
-　　　　　　　　　　　　　　　　
-[Next >](../perfect-squares "Perfect Squares")
-
-## [278. First Bad Version (Easy)](https://leetcode.com/problems/first-bad-version "第一个错误的版本")
-
-<p>You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each version is developed based on the previous version, all the versions after a bad version are also bad.</p>
-
-<p>Suppose you have <code>n</code> versions <code>[1, 2, ..., n]</code> and you want to find out the first bad one, which causes all the following ones to be bad.</p>
-
-<p>You are given an API <code>bool isBadVersion(version)</code> which returns whether <code>version</code> is bad. Implement a function to find the first bad version. You should minimize the number of calls to the API.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, bad = 4
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-call isBadVersion(3) -&gt; false
-call isBadVersion(5)&nbsp;-&gt; true
-call isBadVersion(4)&nbsp;-&gt; true
-Then 4 is the first bad version.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, bad = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= bad &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Similar Questions
-  1. [Find First and Last Position of Element in Sorted Array](../find-first-and-last-position-of-element-in-sorted-array) (Medium)
-  1. [Search Insert Position](../search-insert-position) (Easy)
-  1. [Guess Number Higher or Lower](../guess-number-higher-or-lower) (Easy)
diff --git a/problems/first-bad-version/first_bad_version.go b/problems/first-bad-version/first_bad_version.go
deleted file mode 100644
index d0d112d08..000000000
--- a/problems/first-bad-version/first_bad_version.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem278
diff --git a/problems/first-bad-version/first_bad_version.py b/problems/first-bad-version/first_bad_version.py
deleted file mode 100755
index 7c7a45bb0..000000000
--- a/problems/first-bad-version/first_bad_version.py
+++ /dev/null
@@ -1,14 +0,0 @@
-#!/usr/bin/env python
-
-# The isBadVersion API is already defined for you.
-# @param version, an integer
-# @return a bool
-# def isBadVersion(version):
-
-class Solution:
-    def firstBadVersion(self, n):
-        """
-        :type n: int
-        :rtype: int
-        """
-        
\ No newline at end of file
diff --git a/problems/first-bad-version/first_bad_version_test.go b/problems/first-bad-version/first_bad_version_test.go
deleted file mode 100644
index d0d112d08..000000000
--- a/problems/first-bad-version/first_bad_version_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem278
diff --git a/problems/first-day-where-you-have-been-in-all-the-rooms/README.md b/problems/first-day-where-you-have-been-in-all-the-rooms/README.md
deleted file mode 100644
index 856a5085b..000000000
--- a/problems/first-day-where-you-have-been-in-all-the-rooms/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-weak-characters-in-the-game "The Number of Weak Characters in the Game")
-　　　　　　　　　　　　　　　　
-[Next >](../gcd-sort-of-an-array "GCD Sort of an Array")
-
-## [1997. First Day Where You Have Been in All the Rooms (Medium)](https://leetcode.com/problems/first-day-where-you-have-been-in-all-the-rooms "访问完所有房间的第一天")
-
-<p>There are <code>n</code> rooms you need to visit, labeled from <code>0</code> to <code>n - 1</code>. Each day is labeled, starting from <code>0</code>. You will go in and visit one room a day.</p>
-
-<p>Initially on day <code>0</code>, you visit room <code>0</code>. The <strong>order</strong> you visit the rooms for the coming days is determined by the following <strong>rules</strong> and a given <strong>0-indexed</strong> array <code>nextVisit</code> of length <code>n</code>:</p>
-
-<ul>
-	<li>Assuming that on a day, you visit room <code>i</code>,</li>
-	<li>if you have been in room <code>i</code> an <strong>odd</strong> number of times (<strong>including</strong> the current visit), on the <strong>next</strong> day you will visit a room with a <strong>lower or equal room number</strong> specified by <code>nextVisit[i]</code> where <code>0 &lt;= nextVisit[i] &lt;= i</code>;</li>
-	<li>if you have been in room <code>i</code> an <strong>even</strong> number of times (<strong>including</strong> the current visit), on the <strong>next</strong> day you will visit room <code>(i + 1) mod n</code>.</li>
-</ul>
-
-<p>Return <em>the label of the <strong>first</strong> day where you have been in <strong>all</strong> the rooms</em>. It can be shown that such a day exists. Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nextVisit = [0,0]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-- On day 0, you visit room 0. The total times you have been in room 0 is 1, which is odd.
-&nbsp; On the next day you will visit room nextVisit[0] = 0
-- On day 1, you visit room 0, The total times you have been in room 0 is 2, which is even.
-&nbsp; On the next day you will visit room (0 + 1) mod 2 = 1
-- On day 2, you visit room 1. This is the first day where you have been in all the rooms.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nextVisit = [0,0,2]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong>
-Your room visiting order for each day is: [0,0,1,0,0,1,2,...].
-Day 6 is the first day where you have been in all the rooms.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nextVisit = [0,1,2,0]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong>
-Your room visiting order for each day is: [0,0,1,1,2,2,3,...].
-Day 6 is the first day where you have been in all the rooms.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nextVisit.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nextVisit[i] &lt;= i</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The only way to get to room i+1 is when you are visiting room i and room i has been visited an even number of times.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After visiting room i an odd number of times, you are required to visit room nextVisit[i] where nextVisit[i] <= i. It takes a fixed amount of days for you to come back from room nextVisit[i] to room i. Then, you have visited room i even number of times.nextVisit[i]
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Can you use Dynamic Programming to avoid recomputing the number of days it takes to visit room i from room nextVisit[i]?
-</details>
diff --git a/problems/first-missing-positive/README.md b/problems/first-missing-positive/README.md
deleted file mode 100644
index efea25ae1..000000000
--- a/problems/first-missing-positive/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../combination-sum-ii "Combination Sum II")
-　　　　　　　　　　　　　　　　
-[Next >](../trapping-rain-water "Trapping Rain Water")
-
-## [41. First Missing Positive (Hard)](https://leetcode.com/problems/first-missing-positive "缺失的第一个正数")
-
-<p>Given an unsorted integer array <code>nums</code>, return the smallest missing positive integer.</p>
-
-<p>You must implement an algorithm that runs in <code>O(n)</code> time and uses constant extra space.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,0]
-<strong>Output:</strong> 3
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [3,4,-1,1]
-<strong>Output:</strong> 2
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [7,8,9,11,12]
-<strong>Output:</strong> 1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>5</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [Missing Number](../missing-number) (Easy)
-  1. [Find the Duplicate Number](../find-the-duplicate-number) (Medium)
-  1. [Find All Numbers Disappeared in an Array](../find-all-numbers-disappeared-in-an-array) (Easy)
-  1. [Couples Holding Hands](../couples-holding-hands) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think about how you would solve the problem in non-constant space.  Can you apply that logic to the existing space?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We don't care about duplicates or non-positive integers
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Remember that O(2n) = O(n)
-</details>
diff --git a/problems/first-missing-positive/first_missing_positive.go b/problems/first-missing-positive/first_missing_positive.go
deleted file mode 100644
index 0681dcbe8..000000000
--- a/problems/first-missing-positive/first_missing_positive.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem41
diff --git a/problems/first-missing-positive/first_missing_positive_test.go b/problems/first-missing-positive/first_missing_positive_test.go
deleted file mode 100644
index 0681dcbe8..000000000
--- a/problems/first-missing-positive/first_missing_positive_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem41
diff --git a/problems/first-unique-character-in-a-string/README.md b/problems/first-unique-character-in-a-string/README.md
deleted file mode 100644
index 6935d8b35..000000000
--- a/problems/first-unique-character-in-a-string/README.md
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lexicographical-numbers "Lexicographical Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-absolute-file-path "Longest Absolute File Path")
-
-## [387. First Unique Character in a String (Easy)](https://leetcode.com/problems/first-unique-character-in-a-string "字符串中的第一个唯一字符")
-
-<p>Given a string <code>s</code>, <em>find the first non-repeating character in it and return its index</em>. If it does not exist, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "leetcode"
-<strong>Output:</strong> 0
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "loveleetcode"
-<strong>Output:</strong> 2
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s = "aabb"
-<strong>Output:</strong> -1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Sort Characters By Frequency](../sort-characters-by-frequency) (Medium)
diff --git a/problems/first-unique-character-in-a-string/first_unique_character_in_a_string.go b/problems/first-unique-character-in-a-string/first_unique_character_in_a_string.go
deleted file mode 100644
index 8ec545324..000000000
--- a/problems/first-unique-character-in-a-string/first_unique_character_in_a_string.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem387
-
-func firstUniqChar(s string) int {
-	var count [256]byte
-	l := len(s)
-	for i := 0; i < l; i++ {
-		if count[s[i]] < 2 {
-			count[s[i]]++
-		}
-	}
-	for i := 0; i < l; i++ {
-		if count[s[i]] == 1 {
-			return i
-		}
-	}
-	return -1
-}
diff --git a/problems/first-unique-character-in-a-string/first_unique_character_in_a_string_test.go b/problems/first-unique-character-in-a-string/first_unique_character_in_a_string_test.go
deleted file mode 100644
index 2f905c371..000000000
--- a/problems/first-unique-character-in-a-string/first_unique_character_in_a_string_test.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem387
-
-import "testing"
-
-func TestFirstUniqChar(t *testing.T) {
-	tests := map[string]int{
-		"leetcode":     0,
-		"loveleetcode": 2,
-		"hello world":  0,
-		"aabbccddeeff": -1,
-	}
-
-	for in, want := range tests {
-		got := firstUniqChar(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/first-unique-number/README.md b/problems/first-unique-number/README.md
deleted file mode 100644
index 5c9046d3d..000000000
--- a/problems/first-unique-number/README.md
+++ /dev/null
@@ -1,37 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../leftmost-column-with-at-least-a-one "Leftmost Column with at Least a One")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree "Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree")
-
-## [1429. First Unique Number (Medium)](https://leetcode.com/problems/first-unique-number "第一个唯一数字")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use doubly Linked list with hashmap of pointers to linked list nodes. add unique number to the linked list. When add is called check if the added number is unique then it have to be added to the linked list and if it is repeated remove it from the linked list if exists. When showFirstUnique is called retrieve the head of the linked list.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use queue and check that first element of the queue is always unique.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use set or heap to make running time of each function O(logn).
-</details>
diff --git a/problems/fix-names-in-a-table/README.md b/problems/fix-names-in-a-table/README.md
deleted file mode 100644
index 3a3b17e11..000000000
--- a/problems/fix-names-in-a-table/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../change-the-root-of-a-binary-tree "Change the Root of a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-repeating-substring "Maximum Repeating Substring")
-
-## [1667. Fix Names in a Table (Easy)](https://leetcode.com/problems/fix-names-in-a-table "修复表中的名字")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/fix-names-in-a-table/mysql_schemas.sql b/problems/fix-names-in-a-table/mysql_schemas.sql
deleted file mode 100644
index 2f40f9f43..000000000
--- a/problems/fix-names-in-a-table/mysql_schemas.sql
+++ /dev/null
@@ -1,4 +0,0 @@
-Create table If Not Exists Users (user_id int, name varchar(40));
-Truncate table Users;
-insert into Users (user_id, name) values ('1', 'aLice');
-insert into Users (user_id, name) values ('2', 'bOB');
diff --git a/problems/fix-product-name-format/README.md b/problems/fix-product-name-format/README.md
deleted file mode 100644
index 1ac7a026a..000000000
--- a/problems/fix-product-name-format/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-longest-awesome-substring "Find Longest Awesome Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../make-the-string-great "Make The String Great")
-
-## [1543. Fix Product Name Format (Easy)](https://leetcode.com/problems/fix-product-name-format "产品名称格式修复")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/fix-product-name-format/mysql_schemas.sql b/problems/fix-product-name-format/mysql_schemas.sql
deleted file mode 100644
index cfc6ec934..000000000
--- a/problems/fix-product-name-format/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Sales (sale_id int, product_name varchar(30), sale_date date)
-;
-Truncate table Sales;
-insert into Sales (sale_id, product_name, sale_date) values ('1', 'LCPHONE', '2000-01-16');
-insert into Sales (sale_id, product_name, sale_date) values ('2', 'LCPhone', '2000-01-17');
-insert into Sales (sale_id, product_name, sale_date) values ('3', 'LcPhOnE', '2000-02-18');
-insert into Sales (sale_id, product_name, sale_date) values ('4', 'LCKeyCHAiN', '2000-02-19');
-insert into Sales (sale_id, product_name, sale_date) values ('5', 'LCKeyChain', '2000-02-28');
-insert into Sales (sale_id, product_name, sale_date) values ('6', 'Matryoshka', '2000-03-31');
diff --git a/problems/fixed-point/README.md b/problems/fixed-point/README.md
deleted file mode 100644
index d3983ae1a..000000000
--- a/problems/fixed-point/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-valid-subarrays "Number of Valid Subarrays")
-　　　　　　　　　　　　　　　　
-[Next >](../index-pairs-of-a-string "Index Pairs of a String")
-
-## [1064. Fixed Point (Easy)](https://leetcode.com/problems/fixed-point "不动点")
-
-<p>Given an array <code>A</code> of distinct integers sorted in ascending order, return the smallest index <code>i</code> that satisfies <code>A[i] == i</code>.&nbsp; Return <code>-1</code> if no such <code>i</code> exists.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[-10,-5,0,3,7]</span>
-<strong>Output: </strong><span id="example-output-1">3</span>
-<strong>Explanation: </strong>
-For the given array, <code>A[0] = -10, A[1] = -5, A[2] = 0, A[3] = 3</code>, thus the output is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">[0,2,5,8,17]</span>
-<strong>Output: </strong><span id="example-output-2">0</span>
-<strong>Explanation: </strong>
-<code>A[0] = 0</code>, thus the output is 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-3-1">[-10,-5,3,4,7,9]</span>
-<strong>Output: </strong><span id="example-output-3">-1</span>
-<strong>Explanation: </strong>
-There is no such <code>i</code> that <code>A[i] = i</code>, thus the output is -1.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= A.length &lt; 10^4</code></li>
-	<li><code>-10^9 &lt;= A[i] &lt;= 10^9</code></li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Loop over the array and check the first index i such A[i] == i
-</details>
diff --git a/problems/fizz-buzz-multithreaded/README.md b/problems/fizz-buzz-multithreaded/README.md
deleted file mode 100644
index 64187532e..000000000
--- a/problems/fizz-buzz-multithreaded/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tournament-winners "Tournament Winners")
-　　　　　　　　　　　　　　　　
-[Next >](../how-many-apples-can-you-put-into-the-basket "How Many Apples Can You Put into the Basket")
-
-## [1195. Fizz Buzz Multithreaded (Medium)](https://leetcode.com/problems/fizz-buzz-multithreaded "交替打印字符串")
-
-<p>You have the four functions:</p>
-
-<ul>
-	<li><code>printFizz</code> that prints the word <code>&quot;Fizz&quot;</code> to the console,</li>
-	<li><code>printBuzz</code> that prints the word <code>&quot;Buzz&quot;</code> to the console,</li>
-	<li><code>printFizzBuzz</code> that prints the word <code>&quot;FizzBuzz&quot;</code> to the console, and</li>
-	<li><code>printNumber</code> that prints a given integer to the console.</li>
-</ul>
-
-<p>You are given an instance of the class <code>FizzBuzz</code> that has four functions: <code>fizz</code>, <code>buzz</code>, <code>fizzbuzz</code> and <code>number</code>. The same instance of <code>FizzBuzz</code> will be passed to four different threads:</p>
-
-<ul>
-	<li><strong>Thread A:</strong> calls <code>fizz()</code> that should output the word <code>&quot;Fizz&quot;</code>.</li>
-	<li><strong>Thread B:</strong> calls <code>buzz()</code> that should output the word <code>&quot;Buzz&quot;</code>.</li>
-	<li><strong>Thread C:</strong> calls <code>fizzbuzz()</code> that should output the word <code>&quot;FizzBuzz&quot;</code>.</li>
-	<li><strong>Thread D:</strong> calls <code>number()</code> that should only output the integers.</li>
-</ul>
-
-<p>Modify the given class to output the series <code>[1, 2, &quot;Fizz&quot;, 4, &quot;Buzz&quot;, ...]</code> where the <code>i<sup>th</sup></code> token (<strong>1-indexed</strong>) of the series is:</p>
-
-<ul>
-	<li><code>&quot;FizzBuzz&quot;</code> if <code>i</code> is divisible by <code>3</code> and <code>5</code>,</li>
-	<li><code>&quot;Fizz&quot;</code> if <code>i</code> is divisible by <code>3</code> and not <code>5</code>,</li>
-	<li><code>&quot;Buzz&quot;</code> if <code>i</code> is divisible by <code>5</code> and not <code>3</code>, or</li>
-	<li><code>i</code> if <code>i</code> is not divisible by <code>3</code> or <code>5</code>.</li>
-</ul>
-
-<p>Implement the <code>FizzBuzz</code> class:</p>
-
-<ul>
-	<li><code>FizzBuzz(int n)</code> Initializes the object with the number <code>n</code> that represents the length of the sequence that should be printed.</li>
-	<li><code>void fizz(printFizz)</code> Calls <code>printFizz</code> to output <code>&quot;Fizz&quot;</code>.</li>
-	<li><code>void buzz(printBuzz)</code> Calls <code>printBuzz</code> to output <code>&quot;Buzz&quot;</code>.</li>
-	<li><code>void fizzbuzz(printFizzBuzz)</code> Calls <code>printFizzBuzz</code> to output <code>&quot;FizzBuzz&quot;</code>.</li>
-	<li><code>void number(printNumber)</code> Calls <code>printnumber</code> to output the numbers.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 15
-<strong>Output:</strong> [1,2,"fizz",4,"buzz","fizz",7,8,"fizz","buzz",11,"fizz",13,14,"fizzbuzz"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 5
-<strong>Output:</strong> [1,2,"fizz",4,"buzz"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 50</code></li>
-</ul>
-
-### Related Topics
-  [[Concurrency](../../tag/concurrency/README.md)]
-
-### Similar Questions
-  1. [Fizz Buzz](../fizz-buzz) (Easy)
-  1. [Print Zero Even Odd](../print-zero-even-odd) (Medium)
diff --git a/problems/fizz-buzz/README.md b/problems/fizz-buzz/README.md
deleted file mode 100644
index 228f0fff1..000000000
--- a/problems/fizz-buzz/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-unique-word-abbreviation "Minimum Unique Word Abbreviation")
-　　　　　　　　　　　　　　　　
-[Next >](../arithmetic-slices "Arithmetic Slices")
-
-## [412. Fizz Buzz (Easy)](https://leetcode.com/problems/fizz-buzz "Fizz Buzz")
-
-<p>Given an integer <code>n</code>, return <em>a string array</em> <code>answer</code> (<strong>1-indexed</strong>) <em>where</em>:</p>
-
-<ul>
-	<li><code>answer[i] == &quot;FizzBuzz&quot;</code> if <code>i</code> is divisible by <code>3</code> and <code>5</code>.</li>
-	<li><code>answer[i] == &quot;Fizz&quot;</code> if <code>i</code> is divisible by <code>3</code>.</li>
-	<li><code>answer[i] == &quot;Buzz&quot;</code> if <code>i</code> is divisible by <code>5</code>.</li>
-	<li><code>answer[i] == i</code> if non of the above conditions are true.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 3
-<strong>Output:</strong> ["1","2","Fizz"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 5
-<strong>Output:</strong> ["1","2","Fizz","4","Buzz"]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> n = 15
-<strong>Output:</strong> ["1","2","Fizz","4","Buzz","Fizz","7","8","Fizz","Buzz","11","Fizz","13","14","FizzBuzz"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/fizz-buzz/fizz_buzz.go b/problems/fizz-buzz/fizz_buzz.go
deleted file mode 100644
index 5c7dc8afd..000000000
--- a/problems/fizz-buzz/fizz_buzz.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem412
-
-import "strconv"
-
-func fizzBuzz(n int) []string {
-	s := make([]string, 0, n)
-	for i := 1; i <= n; i++ {
-		str := ""
-		if i%3 == 0 {
-			str += "Fizz"
-		}
-		if i%5 == 0 {
-			str += "Buzz"
-		}
-		if str == "" {
-			str = strconv.Itoa(i)
-		}
-		s = append(s, str)
-	}
-	return s
-}
diff --git a/problems/fizz-buzz/fizz_buzz_test.go b/problems/fizz-buzz/fizz_buzz_test.go
deleted file mode 100644
index 4aba58f6d..000000000
--- a/problems/fizz-buzz/fizz_buzz_test.go
+++ /dev/null
@@ -1,68 +0,0 @@
-package problem412
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   int
-	want []string
-}
-
-func TestFizzBuzz(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: 15,
-			want: []string{
-				"1",
-				"2",
-				"Fizz",
-				"4",
-				"Buzz",
-				"Fizz",
-				"7",
-				"8",
-				"Fizz",
-				"Buzz",
-				"11",
-				"Fizz",
-				"13",
-				"14",
-				"FizzBuzz",
-			},
-		},
-		{
-			in: 5,
-			want: []string{
-				"1",
-				"2",
-				"Fizz",
-				"4",
-				"Buzz",
-			},
-		},
-		{
-			in: 10,
-			want: []string{
-				"1",
-				"2",
-				"Fizz",
-				"4",
-				"Buzz",
-				"Fizz",
-				"7",
-				"8",
-				"Fizz",
-				"Buzz",
-			},
-		},
-	}
-
-	for _, tt := range tests {
-		got := fizzBuzz(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/flatten-2d-vector/README.md b/problems/flatten-2d-vector/README.md
deleted file mode 100644
index 307ebe7a8..000000000
--- a/problems/flatten-2d-vector/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-univalue-subtrees "Count Univalue Subtrees")
-　　　　　　　　　　　　　　　　
-[Next >](../meeting-rooms "Meeting Rooms")
-
-## [251. Flatten 2D Vector (Medium)](https://leetcode.com/problems/flatten-2d-vector "展开二维向量")
-
-<p>Design and implement an iterator to flatten a 2d vector. It should support the following operations: <code>next</code> and <code>hasNext</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-Vector2D iterator = new Vector2D([[1,2],[3],[4]]);
-
-iterator.next(); // return 1
-iterator.next(); // return 2
-iterator.next(); // return 3
-iterator.hasNext(); // return true
-iterator.hasNext(); // return true
-iterator.next(); // return 4
-iterator.hasNext(); // return false
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Notes:</strong></p>
-
-<ol>
-	<li>Please remember to <b>RESET</b> your class variables declared in Vector2D, as static/class variables are <b>persisted across multiple test cases</b>. Please see <a href="https://leetcode.com/faq/" target="_blank">here</a> for more details.</li>
-	<li>You may assume that <code>next()</code> call will always be valid, that is, there will be at least a next element in the 2d vector when <code>next()</code> is called.</li>
-</ol>
-
-<p>&nbsp;</p>
-
-<p><b>Follow up:</b></p>
-
-<p>As an added challenge, try to code it using only <a href="http://www.cplusplus.com/reference/iterator/iterator/" target="_blank">iterators in C++</a> or <a href="http://docs.oracle.com/javase/7/docs/api/java/util/Iterator.html" target="_blank">iterators in Java</a>.</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Iterator](../../tag/iterator/README.md)]
-
-### Similar Questions
-  1. [Binary Search Tree Iterator](../binary-search-tree-iterator) (Medium)
-  1. [Zigzag Iterator](../zigzag-iterator) (Medium)
-  1. [Peeking Iterator](../peeking-iterator) (Medium)
-  1. [Flatten Nested List Iterator](../flatten-nested-list-iterator) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many variables do you need to keep track?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Two variables is all you need. Try with <code>x</code> and <code>y</code>.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Beware of empty rows. It could be the first few rows.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-To write correct code, think about the <a href="https://en.wikipedia.org/wiki/Invariant_(computer_science)" target="_blank">invariant</a> to maintain. What is it?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-The invariant is <code>x</code> and <code>y</code> must always point to a valid point in the 2d vector. Should you maintain your invariant <i>ahead of time</i> or <i>right when you need it</i>?
-</details>
-
-<details>
-<summary>Hint 6</summary>
-Not sure? Think about how you would implement <code>hasNext()</code>. Which is more complex?
-</details>
-
-<details>
-<summary>Hint 7</summary>
-Common logic in two different places should be refactored into a common method.
-</details>
diff --git a/problems/flatten-2d-vector/flatten_2d_vector.go b/problems/flatten-2d-vector/flatten_2d_vector.go
deleted file mode 100644
index 04d026c6e..000000000
--- a/problems/flatten-2d-vector/flatten_2d_vector.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem251
diff --git a/problems/flatten-2d-vector/flatten_2d_vector_test.go b/problems/flatten-2d-vector/flatten_2d_vector_test.go
deleted file mode 100644
index 04d026c6e..000000000
--- a/problems/flatten-2d-vector/flatten_2d_vector_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem251
diff --git a/problems/flatten-a-multilevel-doubly-linked-list/README.md b/problems/flatten-a-multilevel-doubly-linked-list/README.md
deleted file mode 100644
index 45570d484..000000000
--- a/problems/flatten-a-multilevel-doubly-linked-list/README.md
+++ /dev/null
@@ -1,99 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../n-ary-tree-level-order-traversal "N-ary Tree Level Order Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../encode-n-ary-tree-to-binary-tree "Encode N-ary Tree to Binary Tree")
-
-## [430. Flatten a Multilevel Doubly Linked List (Medium)](https://leetcode.com/problems/flatten-a-multilevel-doubly-linked-list "扁平化多级双向链表")
-
-<p>You are given a doubly linked list, which contains nodes that have a next pointer, a previous pointer, and an additional <strong>child pointer</strong>. This child pointer may or may not point to a separate doubly linked list, also containing these special nodes. These child lists may have one or more children of their own, and so on, to produce a <strong>multilevel data structure</strong> as shown in the example below.</p>
-
-<p>Given the <code>head</code> of the first level of the list, <strong>flatten</strong> the list so that all the nodes appear in a single-level, doubly linked list. Let <code>curr</code> be a node with a child list. The nodes in the child list should appear <strong>after</strong> <code>curr</code> and <strong>before</strong> <code>curr.next</code> in the flattened list.</p>
-
-<p>Return <em>the </em><code>head</code><em> of the flattened list. The nodes in the list must have <strong>all</strong> of their child pointers set to </em><code>null</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/09/flatten11.jpg" style="width: 700px; height: 339px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5,6,null,null,null,7,8,9,10,null,null,11,12]
-<strong>Output:</strong> [1,2,3,7,8,11,12,9,10,4,5,6]
-<strong>Explanation:</strong> The multilevel linked list in the input is shown.
-After flattening the multilevel linked list it becomes:
-<img src="https://assets.leetcode.com/uploads/2021/11/09/flatten12.jpg" style="width: 1000px; height: 69px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/09/flatten2.1jpg" style="width: 200px; height: 200px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,null,3]
-<strong>Output:</strong> [1,3,2]
-<strong>Explanation:</strong> The multilevel linked list in the input is shown.
-After flattening the multilevel linked list it becomes:
-<img src="https://assets.leetcode.com/uploads/2021/11/24/list.jpg" style="width: 300px; height: 87px;" />
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = []
-<strong>Output:</strong> []
-<strong>Explanation:</strong> There could be empty list in the input.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of Nodes will not exceed <code>1000</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>How the multilevel linked list is represented in test cases:</strong></p>
-
-<p>We use the multilevel linked list from <strong>Example 1</strong> above:</p>
-
-<pre>
- 1---2---3---4---5---6--NULL
-         |
-         7---8---9---10--NULL
-             |
-             11--12--NULL</pre>
-
-<p>The serialization of each level is as follows:</p>
-
-<pre>
-[1,2,3,4,5,6,null]
-[7,8,9,10,null]
-[11,12,null]
-</pre>
-
-<p>To serialize all levels together, we will add nulls in each level to signify no node connects to the upper node of the previous level. The serialization becomes:</p>
-
-<pre>
-[1,    2,    3, 4, 5, 6, null]
-             |
-[null, null, 7,    8, 9, 10, null]
-                   |
-[            null, 11, 12, null]
-</pre>
-
-<p>Merging the serialization of each level and removing trailing nulls we obtain:</p>
-
-<pre>
-[1,2,3,4,5,6,null,null,null,7,8,9,10,null,null,11,12]
-</pre>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Doubly-Linked List](../../tag/doubly-linked-list/README.md)]
-
-### Similar Questions
-  1. [Flatten Binary Tree to Linked List](../flatten-binary-tree-to-linked-list) (Medium)
diff --git a/problems/flatten-a-multilevel-doubly-linked-list/flatten_a_multilevel_doubly_linked_list.go b/problems/flatten-a-multilevel-doubly-linked-list/flatten_a_multilevel_doubly_linked_list.go
deleted file mode 100644
index cfb9a734b..000000000
--- a/problems/flatten-a-multilevel-doubly-linked-list/flatten_a_multilevel_doubly_linked_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem430
diff --git a/problems/flatten-a-multilevel-doubly-linked-list/flatten_a_multilevel_doubly_linked_list.py b/problems/flatten-a-multilevel-doubly-linked-list/flatten_a_multilevel_doubly_linked_list.py
deleted file mode 100755
index 6e0ca2a4b..000000000
--- a/problems/flatten-a-multilevel-doubly-linked-list/flatten_a_multilevel_doubly_linked_list.py
+++ /dev/null
@@ -1,14 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a Node.
-class Node:
-    def __init__(self, val, prev, next, child):
-        self.val = val
-        self.prev = prev
-        self.next = next
-        self.child = child
-"""
-class Solution:
-    def flatten(self, head: 'Node') -> 'Node':
-        
\ No newline at end of file
diff --git a/problems/flatten-a-multilevel-doubly-linked-list/flatten_a_multilevel_doubly_linked_list_test.go b/problems/flatten-a-multilevel-doubly-linked-list/flatten_a_multilevel_doubly_linked_list_test.go
deleted file mode 100644
index cfb9a734b..000000000
--- a/problems/flatten-a-multilevel-doubly-linked-list/flatten_a_multilevel_doubly_linked_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem430
diff --git a/problems/flatten-binary-tree-to-linked-list/README.md b/problems/flatten-binary-tree-to-linked-list/README.md
deleted file mode 100644
index 3ec60780b..000000000
--- a/problems/flatten-binary-tree-to-linked-list/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-sum-ii "Path Sum II")
-　　　　　　　　　　　　　　　　
-[Next >](../distinct-subsequences "Distinct Subsequences")
-
-## [114. Flatten Binary Tree to Linked List (Medium)](https://leetcode.com/problems/flatten-binary-tree-to-linked-list "二叉树展开为链表")
-
-<p>Given the <code>root</code> of a binary tree, flatten the tree into a &quot;linked list&quot;:</p>
-
-<ul>
-	<li>The &quot;linked list&quot; should use the same <code>TreeNode</code> class where the <code>right</code> child pointer points to the next node in the list and the <code>left</code> child pointer is always <code>null</code>.</li>
-	<li>The &quot;linked list&quot; should be in the same order as a <a href="https://en.wikipedia.org/wiki/Tree_traversal#Pre-order,_NLR" target="_blank"><strong>pre-order</strong><strong> traversal</strong></a> of the binary tree.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/14/flaten.jpg" style="width: 500px; height: 226px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,5,3,4,null,6]
-<strong>Output:</strong> [1,null,2,null,3,null,4,null,5,null,6]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [0]
-<strong>Output:</strong> [0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 2000]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Can you flatten the tree in-place (with <code>O(1)</code> extra space)?
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Flatten a Multilevel Doubly Linked List](../flatten-a-multilevel-doubly-linked-list) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you notice carefully in the flattened tree, each node's right child points to the next node of a pre-order traversal.
-</details>
diff --git a/problems/flatten-binary-tree-to-linked-list/flatten_binary_tree_to_linked_list.go b/problems/flatten-binary-tree-to-linked-list/flatten_binary_tree_to_linked_list.go
deleted file mode 100644
index a99984e17..000000000
--- a/problems/flatten-binary-tree-to-linked-list/flatten_binary_tree_to_linked_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem114
diff --git a/problems/flatten-binary-tree-to-linked-list/flatten_binary_tree_to_linked_list_test.go b/problems/flatten-binary-tree-to-linked-list/flatten_binary_tree_to_linked_list_test.go
deleted file mode 100644
index a99984e17..000000000
--- a/problems/flatten-binary-tree-to-linked-list/flatten_binary_tree_to_linked_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem114
diff --git a/problems/flatten-nested-list-iterator/README.md b/problems/flatten-nested-list-iterator/README.md
deleted file mode 100644
index de96115b9..000000000
--- a/problems/flatten-nested-list-iterator/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-substring-with-at-most-k-distinct-characters "Longest Substring with At Most K Distinct Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../power-of-four "Power of Four")
-
-## [341. Flatten Nested List Iterator (Medium)](https://leetcode.com/problems/flatten-nested-list-iterator "扁平化嵌套列表迭代器")
-
-<p>You are given a nested list of integers <code>nestedList</code>. Each element is either an integer or a list whose elements may also be integers or other lists. Implement an iterator to flatten it.</p>
-
-<p>Implement the <code>NestedIterator</code> class:</p>
-
-<ul>
-	<li><code>NestedIterator(List&lt;NestedInteger&gt; nestedList)</code> Initializes the iterator with the nested list <code>nestedList</code>.</li>
-	<li><code>int next()</code> Returns the next integer in the nested list.</li>
-	<li><code>boolean hasNext()</code> Returns <code>true</code> if there are still some integers in the nested list and <code>false</code> otherwise.</li>
-</ul>
-
-<p>Your code will be tested with the following pseudocode:</p>
-
-<pre>
-initialize iterator with nestedList
-res = []
-while iterator.hasNext()
-    append iterator.next() to the end of res
-return res
-</pre>
-
-<p>If <code>res</code> matches the expected flattened list, then your code will be judged as correct.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nestedList = [[1,1],2,[1,1]]
-<strong>Output:</strong> [1,1,2,1,1]
-<strong>Explanation:</strong> By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,1,2,1,1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nestedList = [1,[4,[6]]]
-<strong>Output:</strong> [1,4,6]
-<strong>Explanation:</strong> By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,4,6].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nestedList.length &lt;= 500</code></li>
-	<li>The values of the integers in the nested list is in the range <code>[-10<sup>6</sup>, 10<sup>6</sup>]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Iterator](../../tag/iterator/README.md)]
-
-### Similar Questions
-  1. [Flatten 2D Vector](../flatten-2d-vector) (Medium)
-  1. [Zigzag Iterator](../zigzag-iterator) (Medium)
-  1. [Mini Parser](../mini-parser) (Medium)
-  1. [Array Nesting](../array-nesting) (Medium)
diff --git a/problems/flatten-nested-list-iterator/flatten_nested_list_iterator.go b/problems/flatten-nested-list-iterator/flatten_nested_list_iterator.go
deleted file mode 100644
index db0204365..000000000
--- a/problems/flatten-nested-list-iterator/flatten_nested_list_iterator.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem341
diff --git a/problems/flatten-nested-list-iterator/flatten_nested_list_iterator.py b/problems/flatten-nested-list-iterator/flatten_nested_list_iterator.py
deleted file mode 100755
index bb4c59534..000000000
--- a/problems/flatten-nested-list-iterator/flatten_nested_list_iterator.py
+++ /dev/null
@@ -1,51 +0,0 @@
-#!/usr/bin/env python
-
-# """
-# This is the interface that allows for creating nested lists.
-# You should not implement it, or speculate about its implementation
-# """
-#class NestedInteger(object):
-#    def isInteger(self):
-#        """
-#        @return True if this NestedInteger holds a single integer, rather than a nested list.
-#        :rtype bool
-#        """
-#
-#    def getInteger(self):
-#        """
-#        @return the single integer that this NestedInteger holds, if it holds a single integer
-#        Return None if this NestedInteger holds a nested list
-#        :rtype int
-#        """
-#
-#    def getList(self):
-#        """
-#        @return the nested list that this NestedInteger holds, if it holds a nested list
-#        Return None if this NestedInteger holds a single integer
-#        :rtype List[NestedInteger]
-#        """
-
-class NestedIterator(object):
-
-    def __init__(self, nestedList):
-        """
-        Initialize your data structure here.
-        :type nestedList: List[NestedInteger]
-        """
-        
-
-    def next(self):
-        """
-        :rtype: int
-        """
-        
-
-    def hasNext(self):
-        """
-        :rtype: bool
-        """
-        
-
-# Your NestedIterator object will be instantiated and called as such:
-# i, v = NestedIterator(nestedList), []
-# while i.hasNext(): v.append(i.next())
\ No newline at end of file
diff --git a/problems/flatten-nested-list-iterator/flatten_nested_list_iterator_test.go b/problems/flatten-nested-list-iterator/flatten_nested_list_iterator_test.go
deleted file mode 100644
index db0204365..000000000
--- a/problems/flatten-nested-list-iterator/flatten_nested_list_iterator_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem341
diff --git a/problems/flip-binary-tree-to-match-preorder-traversal/README.md b/problems/flip-binary-tree-to-match-preorder-traversal/README.md
deleted file mode 100644
index c9c6d7295..000000000
--- a/problems/flip-binary-tree-to-match-preorder-traversal/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../powerful-integers "Powerful Integers")
-　　　　　　　　　　　　　　　　
-[Next >](../equal-rational-numbers "Equal Rational Numbers")
-
-## [971. Flip Binary Tree To Match Preorder Traversal (Medium)](https://leetcode.com/problems/flip-binary-tree-to-match-preorder-traversal "翻转二叉树以匹配先序遍历")
-
-<p>You are given the <code>root</code> of a binary tree with <code>n</code> nodes, where each node is uniquely assigned a value from <code>1</code> to <code>n</code>. You are also given a sequence of <code>n</code> values <code>voyage</code>, which is the <strong>desired</strong> <a href="https://en.wikipedia.org/wiki/Tree_traversal#Pre-order" target="_blank"><strong>pre-order traversal</strong></a> of the binary tree.</p>
-
-<p>Any node in the binary tree can be <strong>flipped</strong> by swapping its left and right subtrees. For example, flipping node 1 will have the following effect:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/15/fliptree.jpg" style="width: 400px; height: 187px;" />
-<p>Flip the <strong>smallest</strong> number of nodes so that the <strong>pre-order traversal</strong> of the tree <strong>matches</strong> <code>voyage</code>.</p>
-
-<p>Return <em>a list of the values of all <strong>flipped</strong> nodes. You may return the answer in <strong>any order</strong>. If it is <strong>impossible</strong> to flip the nodes in the tree to make the pre-order traversal match </em><code>voyage</code><em>, return the list </em><code>[-1]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/02/1219-01.png" style="width: 150px; height: 205px;" />
-<pre>
-<strong>Input:</strong> root = [1,2], voyage = [2,1]
-<strong>Output:</strong> [-1]
-<strong>Explanation:</strong> It is impossible to flip the nodes such that the pre-order traversal matches voyage.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/02/1219-02.png" style="width: 150px; height: 142px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3], voyage = [1,3,2]
-<strong>Output:</strong> [1]
-<strong>Explanation:</strong> Flipping node 1 swaps nodes 2 and 3, so the pre-order traversal matches voyage.</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/02/1219-02.png" style="width: 150px; height: 142px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3], voyage = [1,2,3]
-<strong>Output:</strong> []
-<strong>Explanation:</strong> The tree&#39;s pre-order traversal already matches voyage, so no nodes need to be flipped.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is <code>n</code>.</li>
-	<li><code>n == voyage.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= Node.val, voyage[i] &lt;= n</code></li>
-	<li>All the values in the tree are <strong>unique</strong>.</li>
-	<li>All the values in <code>voyage</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/flip-binary-tree-to-match-preorder-traversal/flip_binary_tree_to_match_preorder_traversal.go b/problems/flip-binary-tree-to-match-preorder-traversal/flip_binary_tree_to_match_preorder_traversal.go
deleted file mode 100644
index 6f689c95b..000000000
--- a/problems/flip-binary-tree-to-match-preorder-traversal/flip_binary_tree_to_match_preorder_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem971
diff --git a/problems/flip-columns-for-maximum-number-of-equal-rows/README.md b/problems/flip-columns-for-maximum-number-of-equal-rows/README.md
deleted file mode 100644
index a1bae20b6..000000000
--- a/problems/flip-columns-for-maximum-number-of-equal-rows/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../greatest-common-divisor-of-strings "Greatest Common Divisor of Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../adding-two-negabinary-numbers "Adding Two Negabinary Numbers")
-
-## [1072. Flip Columns For Maximum Number of Equal Rows (Medium)](https://leetcode.com/problems/flip-columns-for-maximum-number-of-equal-rows "按列翻转得到最大值等行数")
-
-<p>You are given an <code>m x n</code> binary matrix <code>matrix</code>.</p>
-
-<p>You can choose any number of columns in the matrix and flip every cell in that column (i.e., Change the value of the cell from <code>0</code> to <code>1</code> or vice versa).</p>
-
-<p>Return <em>the maximum number of rows that have all values equal after some number of flips</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[0,1],[1,1]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> After flipping no values, 1 row has all values equal.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[0,1],[1,0]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> After flipping values in the first column, both rows have equal values.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[0,0,0],[0,0,1],[1,1,0]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> After flipping values in the first two columns, the last two rows have equal values.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 300</code></li>
-	<li><code>matrix[i][j]</code> is either&nbsp;<code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Flipping a subset of columns is like doing a bitwise XOR of some number K onto each row.  We want rows X with X ^ K = all 0s or all 1s.  This is the same as X = X^K ^K = (all 0s or all 1s) ^ K, so we want to count rows that have opposite bits set.  For example, if K = 1, then we count rows X = (00000...001, or 1111....110).
-</details>
diff --git a/problems/flip-columns-for-maximum-number-of-equal-rows/flip_columns_for_maximum_number_of_equal_rows.go b/problems/flip-columns-for-maximum-number-of-equal-rows/flip_columns_for_maximum_number_of_equal_rows.go
deleted file mode 100644
index b20c67935..000000000
--- a/problems/flip-columns-for-maximum-number-of-equal-rows/flip_columns_for_maximum_number_of_equal_rows.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem1072
-
-import "strings"
-
-func maxEqualRowsAfterFlips(A [][]int) int {
-	count := make(map[string]int, 300)
-	var sb strings.Builder
-	for _, r := range A {
-		r0 := r[0]
-		for _, x := range r {
-			sb.WriteByte(byte(x ^ r0 + '0'))
-		}
-		count[sb.String()]++
-		sb.Reset()
-	}
-
-	res := 0
-
-	for _, c := range count {
-		res = max(res, c)
-	}
-
-	return res
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/flip-equivalent-binary-trees/README.md b/problems/flip-equivalent-binary-trees/README.md
deleted file mode 100644
index ee433b677..000000000
--- a/problems/flip-equivalent-binary-trees/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reveal-cards-in-increasing-order "Reveal Cards In Increasing Order")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-component-size-by-common-factor "Largest Component Size by Common Factor")
-
-## [951. Flip Equivalent Binary Trees (Medium)](https://leetcode.com/problems/flip-equivalent-binary-trees "翻转等价二叉树")
-
-<p>For a binary tree <strong>T</strong>, we can define a <strong>flip operation</strong> as follows: choose any node, and swap the left and right child subtrees.</p>
-
-<p>A binary tree <strong>X</strong>&nbsp;is <em>flip equivalent</em> to a binary tree <strong>Y</strong> if and only if we can make <strong>X</strong> equal to <strong>Y</strong> after some number of flip operations.</p>
-
-<p>Given the roots of two binary trees <code>root1</code> and <code>root2</code>, return <code>true</code> if the two trees are flip equivelent or <code>false</code> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="Flipped Trees Diagram" src="https://assets.leetcode.com/uploads/2018/11/29/tree_ex.png" style="width: 500px; height: 220px;" />
-<pre>
-<strong>Input:</strong> root1 = [1,2,3,4,5,6,null,null,null,7,8], root2 = [1,3,2,null,6,4,5,null,null,null,null,8,7]
-<strong>Output:</strong> true
-<strong>Explanation: </strong>We flipped at nodes with values 1, 3, and 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root1 = [], root2 = []
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root1 = [], root2 = [1]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> root1 = [0,null,1], root2 = []
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> root1 = [0,null,1], root2 = [0,1]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in each tree is in the range <code>[0, 100]</code>.</li>
-	<li>Each tree will have <strong>unique node values</strong> in the range <code>[0, 99]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/flip-equivalent-binary-trees/flip_equivalent_binary_trees.go b/problems/flip-equivalent-binary-trees/flip_equivalent_binary_trees.go
deleted file mode 100644
index 7ca492f29..000000000
--- a/problems/flip-equivalent-binary-trees/flip_equivalent_binary_trees.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem951
diff --git a/problems/flip-equivalent-binary-trees/flip_equivalent_binary_trees_test.go b/problems/flip-equivalent-binary-trees/flip_equivalent_binary_trees_test.go
deleted file mode 100644
index 7ca492f29..000000000
--- a/problems/flip-equivalent-binary-trees/flip_equivalent_binary_trees_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem951
diff --git a/problems/flip-game-ii/README.md b/problems/flip-game-ii/README.md
deleted file mode 100644
index 6814174ea..000000000
--- a/problems/flip-game-ii/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flip-game "Flip Game")
-　　　　　　　　　　　　　　　　
-[Next >](../find-median-from-data-stream "Find Median from Data Stream")
-
-## [294. Flip Game II (Medium)](https://leetcode.com/problems/flip-game-ii "翻转游戏 II")
-
-<p>You are playing the following Flip Game with your friend: Given a string that contains only these two characters: <code>+</code> and <code>-</code>, you and your friend take turns to flip two <b>consecutive</b> <code>&quot;++&quot;</code> into <code>&quot;--&quot;</code>. The game ends when a person can no longer make a move and therefore the other person will be the winner.</p>
-
-<p>Write a function to determine if the starting player can guarantee a win.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> <code>s = &quot;++++&quot;</code>
-<strong>Output:</strong> true 
-<strong>Explanation: </strong>The starting player can guarantee a win by flipping the middle <code>&quot;++&quot;</code> to become <code>&quot;+--+&quot;</code>.
-</pre>
-
-<p><b>Follow up:</b><br />
-Derive your algorithm&#39;s runtime complexity.</p>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Similar Questions
-  1. [Nim Game](../nim-game) (Easy)
-  1. [Flip Game](../flip-game) (Easy)
-  1. [Guess Number Higher or Lower II](../guess-number-higher-or-lower-ii) (Medium)
-  1. [Can I Win](../can-i-win) (Medium)
diff --git a/problems/flip-game-ii/flip_game_ii.go b/problems/flip-game-ii/flip_game_ii.go
deleted file mode 100644
index c122c8495..000000000
--- a/problems/flip-game-ii/flip_game_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem294
diff --git a/problems/flip-game-ii/flip_game_ii_test.go b/problems/flip-game-ii/flip_game_ii_test.go
deleted file mode 100644
index c122c8495..000000000
--- a/problems/flip-game-ii/flip_game_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem294
diff --git a/problems/flip-game/README.md b/problems/flip-game/README.md
deleted file mode 100644
index 944792052..000000000
--- a/problems/flip-game/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../nim-game "Nim Game")
-　　　　　　　　　　　　　　　　
-[Next >](../flip-game-ii "Flip Game II")
-
-## [293. Flip Game (Easy)](https://leetcode.com/problems/flip-game "翻转游戏")
-
-<p>You are playing the following Flip Game with your friend: Given a string that contains only these two characters: <code>+</code> and <code>-</code>, you and your friend take turns to flip two <b>consecutive</b> <code>&quot;++&quot;</code> into <code>&quot;--&quot;</code>. The game ends when a person can no longer make a move and therefore the other person will be the winner.</p>
-
-<p>Write a function to compute all possible states of the string after one valid move.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> <code>s = &quot;++++&quot;</code>
-<strong>Output:</strong> 
-[
-  &quot;--++&quot;,
-  &quot;+--+&quot;,
-  &quot;++--&quot;
-]
-</pre>
-
-<p><strong>Note: </strong>If there is no valid move, return an empty list <code>[]</code>.</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Flip Game II](../flip-game-ii) (Medium)
diff --git a/problems/flip-game/flip_game.go b/problems/flip-game/flip_game.go
deleted file mode 100644
index ef344d529..000000000
--- a/problems/flip-game/flip_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem293
diff --git a/problems/flip-game/flip_game_test.go b/problems/flip-game/flip_game_test.go
deleted file mode 100644
index ef344d529..000000000
--- a/problems/flip-game/flip_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem293
diff --git a/problems/flip-string-to-monotone-increasing/README.md b/problems/flip-string-to-monotone-increasing/README.md
deleted file mode 100644
index 1a4c257d1..000000000
--- a/problems/flip-string-to-monotone-increasing/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../long-pressed-name "Long Pressed Name")
-　　　　　　　　　　　　　　　　
-[Next >](../three-equal-parts "Three Equal Parts")
-
-## [926. Flip String to Monotone Increasing (Medium)](https://leetcode.com/problems/flip-string-to-monotone-increasing "将字符串翻转到单调递增")
-
-<p>A binary string is monotone increasing if it consists of some number of <code>0</code>&#39;s (possibly none), followed by some number of <code>1</code>&#39;s (also possibly none).</p>
-
-<p>You are given a binary string <code>s</code>. You can flip <code>s[i]</code> changing it from <code>0</code> to <code>1</code> or from <code>1</code> to <code>0</code>.</p>
-
-<p>Return <em>the minimum number of flips to make </em><code>s</code><em> monotone increasing</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;00110&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> We flip the last digit to get 00111.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;010110&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We flip to get 011111, or alternatively 000111.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;00011000&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We flip to get 00000000.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/flip-string-to-monotone-increasing/flip_string_to_monotone_increasing.go b/problems/flip-string-to-monotone-increasing/flip_string_to_monotone_increasing.go
deleted file mode 100644
index 3245c672a..000000000
--- a/problems/flip-string-to-monotone-increasing/flip_string_to_monotone_increasing.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem926
diff --git a/problems/flip-string-to-monotone-increasing/flip_string_to_monotone_increasing_test.go b/problems/flip-string-to-monotone-increasing/flip_string_to_monotone_increasing_test.go
deleted file mode 100644
index 3245c672a..000000000
--- a/problems/flip-string-to-monotone-increasing/flip_string_to_monotone_increasing_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem926
diff --git a/problems/flipping-an-image/README.md b/problems/flipping-an-image/README.md
deleted file mode 100644
index dee216608..000000000
--- a/problems/flipping-an-image/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../masking-personal-information "Masking Personal Information")
-　　　　　　　　　　　　　　　　
-[Next >](../find-and-replace-in-string "Find And Replace in String")
-
-## [832. Flipping an Image (Easy)](https://leetcode.com/problems/flipping-an-image "翻转图像")
-
-<p>Given an <code>n x n</code> binary matrix <code>image</code>, flip the image <strong>horizontally</strong>, then invert it, and return <em>the resulting image</em>.</p>
-
-<p>To flip an image horizontally means that each row of the image is reversed.</p>
-
-<ul>
-	<li>For example, flipping <code>[1,1,0]</code> horizontally results in <code>[0,1,1]</code>.</li>
-</ul>
-
-<p>To invert an image means that each <code>0</code> is replaced by <code>1</code>, and each <code>1</code> is replaced by <code>0</code>.</p>
-
-<ul>
-	<li>For example, inverting <code>[0,1,1]</code> results in <code>[1,0,0]</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> image = [[1,1,0],[1,0,1],[0,0,0]]
-<strong>Output:</strong> [[1,0,0],[0,1,0],[1,1,1]]
-<strong>Explanation:</strong> First reverse each row: [[0,1,1],[1,0,1],[0,0,0]].
-Then, invert the image: [[1,0,0],[0,1,0],[1,1,1]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> image = [[1,1,0,0],[1,0,0,1],[0,1,1,1],[1,0,1,0]]
-<strong>Output:</strong> [[1,1,0,0],[0,1,1,0],[0,0,0,1],[1,0,1,0]]
-<strong>Explanation:</strong> First reverse each row: [[0,0,1,1],[1,0,0,1],[1,1,1,0],[0,1,0,1]].
-Then invert the image: [[1,1,0,0],[0,1,1,0],[0,0,0,1],[1,0,1,0]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == image.length</code></li>
-	<li><code>n == image[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-	<li><code>images[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/flipping-an-image/flipping_an_image.go b/problems/flipping-an-image/flipping_an_image.go
deleted file mode 100644
index bb3ae96b1..000000000
--- a/problems/flipping-an-image/flipping_an_image.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem832
-
-func flipAndInvertImage(A [][]int) [][]int {
-	for _, row := range A {
-		for i, j := 0, len(row)-1; i <= j; i, j = i+1, j-1 {
-			row[i], row[j] = row[j]^1, row[i]^1
-		}
-	}
-	return A
-}
diff --git a/problems/flipping-an-image/flipping_an_image_test.go b/problems/flipping-an-image/flipping_an_image_test.go
deleted file mode 100644
index d16d5e97b..000000000
--- a/problems/flipping-an-image/flipping_an_image_test.go
+++ /dev/null
@@ -1,48 +0,0 @@
-package problem832
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   [][]int
-	want [][]int
-}
-
-func TestFlipAndInvertImage(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{1, 1, 0},
-				{1, 0, 1},
-				{0, 0, 0},
-			},
-			want: [][]int{
-				{1, 0, 0},
-				{0, 1, 0},
-				{1, 1, 1},
-			},
-		},
-		{
-			in: [][]int{
-				{1, 1, 0, 0},
-				{1, 0, 0, 1},
-				{0, 1, 1, 1},
-				{1, 0, 1, 0},
-			},
-			want: [][]int{
-				{1, 1, 0, 0},
-				{0, 1, 1, 0},
-				{0, 0, 0, 1},
-				{1, 0, 1, 0},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := flipAndInvertImage(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/flood-fill/README.md b/problems/flood-fill/README.md
deleted file mode 100644
index b47ff858f..000000000
--- a/problems/flood-fill/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../my-calendar-iii "My Calendar III")
-　　　　　　　　　　　　　　　　
-[Next >](../sentence-similarity "Sentence Similarity")
-
-## [733. Flood Fill (Easy)](https://leetcode.com/problems/flood-fill "图像渲染")
-
-<p>An image is represented by an <code>m x n</code> integer grid <code>image</code> where <code>image[i][j]</code> represents the pixel value of the image.</p>
-
-<p>You are also given three integers <code>sr</code>, <code>sc</code>, and <code>newColor</code>. You should perform a <strong>flood fill</strong> on the image starting from the pixel <code>image[sr][sc]</code>.</p>
-
-<p>To perform a <strong>flood fill</strong>, consider the starting pixel, plus any pixels connected <strong>4-directionally</strong> to the starting pixel of the same color as the starting pixel, plus any pixels connected <strong>4-directionally</strong> to those pixels (also with the same color), and so on. Replace the color of all of the aforementioned pixels with <code>newColor</code>.</p>
-
-<p>Return <em>the modified image after performing the flood fill</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/01/flood1-grid.jpg" style="width: 613px; height: 253px;" />
-<pre>
-<strong>Input:</strong> image = [[1,1,1],[1,1,0],[1,0,1]], sr = 1, sc = 1, newColor = 2
-<strong>Output:</strong> [[2,2,2],[2,2,0],[2,0,1]]
-<strong>Explanation:</strong> From the center of the image with position (sr, sc) = (1, 1) (i.e., the red pixel), all pixels connected by a path of the same color as the starting pixel (i.e., the blue pixels) are colored with the new color.
-Note the bottom corner is not colored 2, because it is not 4-directionally connected to the starting pixel.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> image = [[0,0,0],[0,0,0]], sr = 0, sc = 0, newColor = 2
-<strong>Output:</strong> [[2,2,2],[2,2,2]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == image.length</code></li>
-	<li><code>n == image[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>0 &lt;= image[i][j], newColor &lt; 2<sup>16</sup></code></li>
-	<li><code>0 &lt;= sr &lt;&nbsp;m</code></li>
-	<li><code>0 &lt;= sc &lt;&nbsp;n</code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Island Perimeter](../island-perimeter) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Write a recursive function that paints the pixel if it's the correct color, then recurses on neighboring pixels.
-</details>
diff --git a/problems/flood-fill/flood_fill.go b/problems/flood-fill/flood_fill.go
deleted file mode 100644
index 3ea542c93..000000000
--- a/problems/flood-fill/flood_fill.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem733
diff --git a/problems/flood-fill/flood_fill_test.go b/problems/flood-fill/flood_fill_test.go
deleted file mode 100644
index 3ea542c93..000000000
--- a/problems/flood-fill/flood_fill_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem733
diff --git a/problems/flower-planting-with-no-adjacent/README.md b/problems/flower-planting-with-no-adjacent/README.md
deleted file mode 100644
index 18eb5ebdd..000000000
--- a/problems/flower-planting-with-no-adjacent/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../robot-bounded-in-circle "Robot Bounded In Circle")
-　　　　　　　　　　　　　　　　
-[Next >](../partition-array-for-maximum-sum "Partition Array for Maximum Sum")
-
-## [1042. Flower Planting With No Adjacent (Medium)](https://leetcode.com/problems/flower-planting-with-no-adjacent "不邻接植花")
-
-<p>You have <code>n</code> gardens, labeled from <code>1</code> to <code>n</code>, and an array <code>paths</code> where <code>paths[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> describes a bidirectional path between garden <code>x<sub>i</sub></code> to garden <code>y<sub>i</sub></code>. In each garden, you want to plant one of 4 types of flowers.</p>
-
-<p>All gardens have <strong>at most 3</strong> paths coming into or leaving it.</p>
-
-<p>Your task is to choose a flower type for each garden such that, for any two gardens connected by a path, they have different types of flowers.</p>
-
-<p>Return <em><strong>any</strong> such a choice as an array </em><code>answer</code><em>, where </em><code>answer[i]</code><em> is the type of flower planted in the </em><code>(i+1)<sup>th</sup></code><em> garden. The flower types are denoted </em><code>1</code><em>, </em><code>2</code><em>, </em><code>3</code><em>, or </em><code>4</code><em>. It is guaranteed an answer exists.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, paths = [[1,2],[2,3],[3,1]]
-<strong>Output:</strong> [1,2,3]
-<strong>Explanation:</strong>
-Gardens 1 and 2 have different types.
-Gardens 2 and 3 have different types.
-Gardens 3 and 1 have different types.
-Hence, [1,2,3] is a valid answer. Other valid answers include [1,2,4], [1,4,2], and [3,2,1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, paths = [[1,2],[3,4]]
-<strong>Output:</strong> [1,2,1,2]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, paths = [[1,2],[2,3],[3,4],[4,1],[1,3],[2,4]]
-<strong>Output:</strong> [1,2,3,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= paths.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>paths[i].length == 2</code></li>
-	<li><code>1 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= n</code></li>
-	<li><code>x<sub>i</sub> != y<sub>i</sub></code></li>
-	<li>Every garden has <strong>at most 3</strong> paths coming into or leaving it.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since each garden is connected to at most 3 gardens, there's always an available color for each garden.  For example, if one garden is next to gardens with colors 1, 3, 4,  then color #2 is available.
-</details>
diff --git a/problems/flower-planting-with-no-adjacent/flower_planting_with_no_adjacent.go b/problems/flower-planting-with-no-adjacent/flower_planting_with_no_adjacent.go
deleted file mode 100644
index b07231504..000000000
--- a/problems/flower-planting-with-no-adjacent/flower_planting_with_no_adjacent.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem1042
-
-func gardenNoAdj(N int, paths [][]int) []int {
-	ans, adjGarden, flowerUsed := make([]int, N), make([][]int, N), make([][4]bool, N)
-	for _, path := range paths {
-		if path[0] > path[1] {
-			path[0], path[1] = path[1], path[0]
-		}
-		adjGarden[path[0]-1] = append(adjGarden[path[0]-1], path[1]-1)
-	}
-	for i := 0; i < N; i++ {
-		for flower, used := range flowerUsed[i] {
-			if !used {
-				ans[i] = flower + 1
-				break
-			}
-		}
-		for _, garden := range adjGarden[i] {
-			flowerUsed[garden][ans[i]-1] = true
-		}
-	}
-	return ans
-}
diff --git a/problems/flower-planting-with-no-adjacent/flower_planting_with_no_adjacent_test.go b/problems/flower-planting-with-no-adjacent/flower_planting_with_no_adjacent_test.go
deleted file mode 100644
index 5abf05d23..000000000
--- a/problems/flower-planting-with-no-adjacent/flower_planting_with_no_adjacent_test.go
+++ /dev/null
@@ -1,52 +0,0 @@
-package problem1042
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	n     int
-	paths [][]int
-	want  []int
-}
-
-func TestGardenNoAdj(t *testing.T) {
-	tests := [...]testType{
-		{
-			n: 3,
-			paths: [][]int{
-				{1, 2},
-				{2, 3},
-				{3, 1},
-			},
-			want: []int{1, 2, 3},
-		},
-		{
-			n: 4,
-			paths: [][]int{
-				{1, 2},
-				{3, 4},
-			},
-			want: []int{1, 2, 1, 2},
-		},
-		{
-			n: 4,
-			paths: [][]int{
-				{1, 2},
-				{2, 3},
-				{3, 4},
-				{4, 1},
-				{1, 3},
-				{2, 4},
-			},
-			want: []int{1, 2, 3, 4},
-		},
-	}
-	for _, tt := range tests {
-		got := gardenNoAdj(tt.n, tt.paths)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.n, got, tt.want)
-		}
-	}
-}
diff --git a/problems/form-array-by-concatenating-subarrays-of-another-array/README.md b/problems/form-array-by-concatenating-subarrays-of-another-array/README.md
deleted file mode 100644
index 6cc68179e..000000000
--- a/problems/form-array-by-concatenating-subarrays-of-another-array/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-nice-substring "Longest Nice Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../map-of-highest-peak "Map of Highest Peak")
-
-## [1764. Form Array by Concatenating Subarrays of Another Array (Medium)](https://leetcode.com/problems/form-array-by-concatenating-subarrays-of-another-array "通过连接另一个数组的子数组得到一个数组")
-
-<p>You are given a 2D integer array <code>groups</code> of length <code>n</code>. You are also given an integer array <code>nums</code>.</p>
-
-<p>You are asked if you can choose <code>n</code> <strong>disjoint </strong>subarrays from the array <code>nums</code> such that the <code>i<sup>th</sup></code> subarray is equal to <code>groups[i]</code> (<b>0-indexed</b>), and if <code>i &gt; 0</code>, the <code>(i-1)<sup>th</sup></code> subarray appears <strong>before</strong> the <code>i<sup>th</sup></code> subarray in <code>nums</code> (i.e. the subarrays must be in the same order as <code>groups</code>).</p>
-
-<p>Return <code>true</code> <em>if you can do this task, and</em> <code>false</code> <em>otherwise</em>.</p>
-
-<p>Note that the subarrays are <strong>disjoint</strong> if and only if there is no index <code>k</code> such that <code>nums[k]</code> belongs to more than one subarray. A subarray is a contiguous sequence of elements within an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> groups = [[1,-1,-1],[3,-2,0]], nums = [1,-1,0,1,-1,-1,3,-2,0]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can choose the 0<sup>th</sup> subarray as [1,-1,0,<u><strong>1,-1,-1</strong></u>,3,-2,0] and the 1<sup>st</sup> one as [1,-1,0,1,-1,-1,<u><strong>3,-2,0</strong></u>].
-These subarrays are disjoint as they share no common nums[k] element.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> groups = [[10,-2],[1,2,3,4]], nums = [1,2,3,4,10,-2]
-<strong>Output:</strong> false
-<strong>Explanation: </strong>Note that choosing the subarrays [<u><strong>1,2,3,4</strong></u>,10,-2] and [1,2,3,4,<u><strong>10,-2</strong></u>] is incorrect because they are not in the same order as in groups.
-[10,-2] must come before [1,2,3,4].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> groups = [[1,2,3],[3,4]], nums = [7,7,1,2,3,4,7,7]
-<strong>Output:</strong> false
-<strong>Explanation: </strong>Note that choosing the subarrays [7,7,<u><strong>1,2,3</strong></u>,4,7,7] and [7,7,1,2,<u><strong>3,4</strong></u>,7,7] is invalid because they are not disjoint.
-They share a common elements nums[4] (0-indexed).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>groups.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>3</sup></code></li>
-	<li><code>1 &lt;= groups[i].length, sum(groups[i].length) &lt;= 10<sup><span style="font-size: 10.8333px;">3</span></sup></code></li>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>3</sup></code></li>
-	<li><code>-10<sup>7</sup> &lt;= groups[i][j], nums[k] &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-When we use a subarray, the room for the next subarrays will be the suffix after the used subarray.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If we can match a group with multiple subarrays, we should choose the first one, as this will just leave the largest room for the next subarrays.
-</details>
diff --git a/problems/form-largest-integer-with-digits-that-add-up-to-target/README.md b/problems/form-largest-integer-with-digits-that-add-up-to-target/README.md
deleted file mode 100644
index 939b93d2f..000000000
--- a/problems/form-largest-integer-with-digits-that-add-up-to-target/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-good-nodes-in-binary-tree "Count Good Nodes in Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-students-doing-homework-at-a-given-time "Number of Students Doing Homework at a Given Time")
-
-## [1449. Form Largest Integer With Digits That Add up to Target (Hard)](https://leetcode.com/problems/form-largest-integer-with-digits-that-add-up-to-target "数位成本和为目标值的最大数字")
-
-<p>Given an array of integers <code>cost</code> and an integer <code>target</code>, return <em>the <strong>maximum</strong> integer you can paint under the following rules</em>:</p>
-
-<ul>
-	<li>The cost of painting a digit <code>(i + 1)</code> is given by <code>cost[i]</code> (<strong>0-indexed</strong>).</li>
-	<li>The total cost used must be equal to <code>target</code>.</li>
-	<li>The integer does not have <code>0</code> digits.</li>
-</ul>
-
-<p>Since the answer may be very large, return it as a string. If there is no way to paint any integer given the condition, return <code>&quot;0&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> cost = [4,3,2,5,6,7,2,5,5], target = 9
-<strong>Output:</strong> &quot;7772&quot;
-<strong>Explanation:</strong> The cost to paint the digit &#39;7&#39; is 2, and the digit &#39;2&#39; is 3. Then cost(&quot;7772&quot;) = 2*3+ 3*1 = 9. You could also paint &quot;977&quot;, but &quot;7772&quot; is the largest number.
-<strong>Digit    cost</strong>
-  1  -&gt;   4
-  2  -&gt;   3
-  3  -&gt;   2
-  4  -&gt;   5
-  5  -&gt;   6
-  6  -&gt;   7
-  7  -&gt;   2
-  8  -&gt;   5
-  9  -&gt;   5
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> cost = [7,6,5,5,5,6,8,7,8], target = 12
-<strong>Output:</strong> &quot;85&quot;
-<strong>Explanation:</strong> The cost to paint the digit &#39;8&#39; is 7, and the digit &#39;5&#39; is 5. Then cost(&quot;85&quot;) = 7 + 5 = 12.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> cost = [2,4,6,2,4,6,4,4,4], target = 5
-<strong>Output:</strong> &quot;0&quot;
-<strong>Explanation:</strong> It is impossible to paint any integer with total cost equal to target.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>cost.length == 9</code></li>
-	<li><code>1 &lt;= cost[i], target &lt;= 5000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming to find the maximum digits to paint given a total cost.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Build the largest number possible using this DP table.
-</details>
diff --git a/problems/four-divisors/README.md b/problems/four-divisors/README.md
deleted file mode 100644
index 0bdc98273..000000000
--- a/problems/four-divisors/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../create-target-array-in-the-given-order "Create Target Array in the Given Order")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-there-is-a-valid-path-in-a-grid "Check if There is a Valid Path in a Grid")
-
-## [1390. Four Divisors (Medium)](https://leetcode.com/problems/four-divisors "四因数")
-
-<p>Given an integer array <code>nums</code>, return <em>the sum of divisors of the integers in that array that have exactly four divisors</em>. If there is no such integer in the array, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [21,4,7]
-<strong>Output:</strong> 32
-<strong>Explanation:</strong> 
-21 has 4 divisors: 1, 3, 7, 21
-4 has 3 divisors: 1, 2, 4
-7 has 2 divisors: 1, 7
-The answer is the sum of divisors of 21 only.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [21,21]
-<strong>Output:</strong> 64
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the divisors of each element in the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You only need to loop to the square root of a number to find its divisors.
-</details>
diff --git a/problems/fraction-addition-and-subtraction/README.md b/problems/fraction-addition-and-subtraction/README.md
deleted file mode 100644
index 56530a40d..000000000
--- a/problems/fraction-addition-and-subtraction/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tag-validator "Tag Validator")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-square "Valid Square")
-
-## [592. Fraction Addition and Subtraction (Medium)](https://leetcode.com/problems/fraction-addition-and-subtraction "分数加减运算")
-
-<p>Given a string <code>expression</code> representing an expression of fraction addition and subtraction, return the calculation result in string format.</p>
-
-<p>The final result should be an <a href="https://en.wikipedia.org/wiki/Irreducible_fraction" target="_blank">irreducible fraction</a>. If your final result is an integer, say <code>2</code>, you need to change it to the format of a fraction that has a denominator <code>1</code>. So in this case, <code>2</code> should be converted to <code>2/1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;-1/2+1/2&quot;
-<strong>Output:</strong> &quot;0/1&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;-1/2+1/2+1/3&quot;
-<strong>Output:</strong> &quot;1/3&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;1/3-1/2&quot;
-<strong>Output:</strong> &quot;-1/6&quot;
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;5/3+1/3&quot;
-<strong>Output:</strong> &quot;2/1&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The input string only contains <code>&#39;0&#39;</code> to <code>&#39;9&#39;</code>, <code>&#39;/&#39;</code>, <code>&#39;+&#39;</code> and <code>&#39;-&#39;</code>. So does the output.</li>
-	<li>Each fraction (input and output) has the format <code>&plusmn;numerator/denominator</code>. If the first input fraction or the output is positive, then <code>&#39;+&#39;</code> will be omitted.</li>
-	<li>The input only contains valid <b>irreducible fractions</b>, where the <b>numerator</b> and <b>denominator</b> of each fraction will always be in the range <code>[1, 10]</code>. If the denominator is <code>1</code>, it means this fraction is actually an integer in a fraction format defined above.</li>
-	<li>The number of given fractions will be in the range <code>[1, 10]</code>.</li>
-	<li>The numerator and denominator of the <b>final result</b> are guaranteed to be valid and in the range of <strong>32-bit</strong> int.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Solve the Equation](../solve-the-equation) (Medium)
diff --git a/problems/fraction-addition-and-subtraction/fraction_addition_and_subtraction.go b/problems/fraction-addition-and-subtraction/fraction_addition_and_subtraction.go
deleted file mode 100644
index 10476c67c..000000000
--- a/problems/fraction-addition-and-subtraction/fraction_addition_and_subtraction.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem592
diff --git a/problems/fraction-addition-and-subtraction/fraction_addition_and_subtraction_test.go b/problems/fraction-addition-and-subtraction/fraction_addition_and_subtraction_test.go
deleted file mode 100644
index 10476c67c..000000000
--- a/problems/fraction-addition-and-subtraction/fraction_addition_and_subtraction_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem592
diff --git a/problems/fraction-to-recurring-decimal/README.md b/problems/fraction-to-recurring-decimal/README.md
deleted file mode 100644
index d038a73c0..000000000
--- a/problems/fraction-to-recurring-decimal/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../compare-version-numbers "Compare Version Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../two-sum-ii-input-array-is-sorted "Two Sum II - Input array is sorted")
-
-## [166. Fraction to Recurring Decimal (Medium)](https://leetcode.com/problems/fraction-to-recurring-decimal "分数到小数")
-
-<p>Given two integers representing the <code>numerator</code> and <code>denominator</code> of a fraction, return <em>the fraction in string format</em>.</p>
-
-<p>If the fractional part is repeating, enclose the repeating part in parentheses.</p>
-
-<p>If multiple answers are possible, return <strong>any of them</strong>.</p>
-
-<p>It is <strong>guaranteed</strong> that the length of the answer string is less than <code>10<sup>4</sup></code> for all the given inputs.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> numerator = 1, denominator = 2
-<strong>Output:</strong> "0.5"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> numerator = 2, denominator = 1
-<strong>Output:</strong> "2"
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> numerator = 2, denominator = 3
-<strong>Output:</strong> "0.(6)"
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> numerator = 4, denominator = 333
-<strong>Output:</strong> "0.(012)"
-</pre><p><strong>Example 5:</strong></p>
-<pre><strong>Input:</strong> numerator = 1, denominator = 5
-<strong>Output:</strong> "0.2"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;=&nbsp;numerator, denominator &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>denominator != 0</code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-No scary math, just apply elementary math knowledge. Still remember how to perform a <i>long division</i>?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try a long division on 4/9, the repeating part is obvious. Now try 4/333. Do you see a pattern?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Notice that once the remainder starts repeating, so does the divided result.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Be wary of edge cases! List out as many test cases as you can think of and test your code thoroughly.
-</details>
diff --git a/problems/fraction-to-recurring-decimal/fraction_to_recurring_decimal.go b/problems/fraction-to-recurring-decimal/fraction_to_recurring_decimal.go
deleted file mode 100644
index f955807cf..000000000
--- a/problems/fraction-to-recurring-decimal/fraction_to_recurring_decimal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem166
diff --git a/problems/fraction-to-recurring-decimal/fraction_to_recurring_decimal_test.go b/problems/fraction-to-recurring-decimal/fraction_to_recurring_decimal_test.go
deleted file mode 100644
index f955807cf..000000000
--- a/problems/fraction-to-recurring-decimal/fraction_to_recurring_decimal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem166
diff --git a/problems/freedom-trail/README.md b/problems/freedom-trail/README.md
deleted file mode 100644
index 3590b27dd..000000000
--- a/problems/freedom-trail/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-bottom-left-tree-value "Find Bottom Left Tree Value")
-　　　　　　　　　　　　　　　　
-[Next >](../find-largest-value-in-each-tree-row "Find Largest Value in Each Tree Row")
-
-## [514. Freedom Trail (Hard)](https://leetcode.com/problems/freedom-trail "自由之路")
-
-<p>In the video game Fallout 4, the quest <strong>&quot;Road to Freedom&quot;</strong> requires players to reach a metal dial called the <strong>&quot;Freedom Trail Ring&quot;</strong> and use the dial to spell a specific keyword to open the door.</p>
-
-<p>Given a string <code>ring</code> that represents the code engraved on the outer ring and another string <code>key</code> that represents the keyword that needs to be spelled, return <em>the minimum number of steps to spell all the characters in the keyword</em>.</p>
-
-<p>Initially, the first character of the ring is aligned at the <code>&quot;12:00&quot;</code> direction. You should spell all the characters in <code>key</code> one by one by rotating <code>ring</code> clockwise or anticlockwise to make each character of the string key aligned at the <code>&quot;12:00&quot;</code> direction and then by pressing the center button.</p>
-
-<p>At the stage of rotating the ring to spell the key character <code>key[i]</code>:</p>
-
-<ol>
-	<li>You can rotate the ring clockwise or anticlockwise by one place, which counts as <strong>one step</strong>. The final purpose of the rotation is to align one of <code>ring</code>&#39;s characters at the <code>&quot;12:00&quot;</code> direction, where this character must equal <code>key[i]</code>.</li>
-	<li>If the character <code>key[i]</code> has been aligned at the <code>&quot;12:00&quot;</code> direction, press the center button to spell, which also counts as <strong>one step</strong>. After the pressing, you could begin to spell the next character in the key (next stage). Otherwise, you have finished all the spelling.</li>
-</ol>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://assets.leetcode.com/uploads/2018/10/22/ring.jpg" style="width: 450px; height: 450px;" />
-<pre>
-<strong>Input:</strong> ring = &quot;godding&quot;, key = &quot;gd&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-For the first key character &#39;g&#39;, since it is already in place, we just need 1 step to spell this character. 
-For the second key character &#39;d&#39;, we need to rotate the ring &quot;godding&quot; anticlockwise by two steps to make it become &quot;ddinggo&quot;.
-Also, we need 1 more step for spelling.
-So the final output is 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> ring = &quot;godding&quot;, key = &quot;godding&quot;
-<strong>Output:</strong> 13
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= ring.length, key.length &lt;= 100</code></li>
-	<li><code>ring</code> and <code>key</code> consist of only lower case English letters.</li>
-	<li>It is guaranteed that <code>key</code> could always be spelled by rotating <code>ring</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
diff --git a/problems/freedom-trail/freedom_trail.go b/problems/freedom-trail/freedom_trail.go
deleted file mode 100644
index 93cda278f..000000000
--- a/problems/freedom-trail/freedom_trail.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem514
diff --git a/problems/freedom-trail/freedom_trail_test.go b/problems/freedom-trail/freedom_trail_test.go
deleted file mode 100644
index 93cda278f..000000000
--- a/problems/freedom-trail/freedom_trail_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem514
diff --git a/problems/frequency-of-the-most-frequent-element/README.md b/problems/frequency-of-the-most-frequent-element/README.md
deleted file mode 100644
index 82187cf4f..000000000
--- a/problems/frequency-of-the-most-frequent-element/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-digits-in-base-k "Sum of Digits in Base K")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-substring-of-all-vowels-in-order "Longest Substring Of All Vowels in Order")
-
-## [1838. Frequency of the Most Frequent Element (Medium)](https://leetcode.com/problems/frequency-of-the-most-frequent-element "最高频元素的频数")
-
-<p>The <strong>frequency</strong> of an element is the number of times it occurs in an array.</p>
-
-<p>You are given an integer array <code>nums</code> and an integer <code>k</code>. In one operation, you can choose an index of <code>nums</code> and increment the element at that index by <code>1</code>.</p>
-
-<p>Return <em>the <strong>maximum possible frequency</strong> of an element after performing <strong>at most</strong> </em><code>k</code><em> operations</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,4], k = 5
-<strong>Output:</strong> 3<strong>
-Explanation:</strong> Increment the first element three times and the second element two times to make nums = [4,4,4].
-4 has a frequency of 3.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,4,8,13], k = 5
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are multiple optimal solutions:
-- Increment the first element three times to make nums = [4,4,8,13]. 4 has a frequency of 2.
-- Increment the second element four times to make nums = [1,8,8,13]. 8 has a frequency of 2.
-- Increment the third element five times to make nums = [1,4,13,13]. 13 has a frequency of 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,9,6], k = 2
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that you can try all values in a brute force manner and find the maximum frequency of that value.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To find the maximum frequency of a value consider the biggest elements smaller than or equal to this value
-</details>
diff --git a/problems/friend-circles/README.md b/problems/friend-circles/README.md
deleted file mode 100644
index dea5595e2..000000000
--- a/problems/friend-circles/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-boxes "Remove Boxes")
-　　　　　　　　　　　　　　　　
-[Next >](../split-array-with-equal-sum "Split Array with Equal Sum")
-
-## [547. Friend Circles (Medium)](https://leetcode.com/problems/friend-circles "朋友圈")
-
-<p>There are <b>N</b> students in a class. Some of them are friends, while some are not. Their friendship is transitive in nature. For example, if A is a <b>direct</b> friend of B, and B is a <b>direct</b> friend of C, then A is an <b>indirect</b> friend of C. And we defined a friend circle is a group of students who are direct or indirect friends.</p>
-
-<p>Given a <b>N*N</b> matrix <b>M</b> representing the friend relationship between students in the class. If M[i][j] = 1, then the i<sub>th</sub> and j<sub>th</sub> students are <b>direct</b> friends with each other, otherwise not. And you have to output the total number of friend circles among all the students.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<b>Input:</b> 
-[[1,1,0],
- [1,1,0],
- [0,0,1]]
-<b>Output:</b> 2
-<b>Explanation:</b>The 0<sub>th</sub> and 1<sub>st</sub> students are direct friends, so they are in a friend circle. 
-The 2<sub>nd</sub> student himself is in a friend circle. So return 2.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<b>Input:</b> 
-[[1,1,0],
- [1,1,1],
- [0,1,1]]
-<b>Output:</b> 1
-<b>Explanation:</b>The 0<sub>th</sub> and 1<sub>st</sub> students are direct friends, the 1<sub>st</sub> and 2<sub>nd</sub> students are direct friends, 
-so the 0<sub>th</sub> and 2<sub>nd</sub> students are indirect friends. All of them are in the same friend circle, so return 1.
-
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= N &lt;= 200</code></li>
-	<li><code>M[i][i] == 1</code></li>
-	<li><code>M[i][j] == M[j][i]</code></li>
-</ul>
-
-### Related Topics
-  [[Depth-first Search](../../tag/depth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-
-### Similar Questions
-  1. [Number of Connected Components in an Undirected Graph](../number-of-connected-components-in-an-undirected-graph) (Medium)
-  1. [Robot Return to Origin](../robot-return-to-origin) (Easy)
-  1. [Sentence Similarity](../sentence-similarity) (Easy)
-  1. [Sentence Similarity II](../sentence-similarity-ii) (Medium)
-  1. [The Earliest Moment When Everyone Become Friends](../the-earliest-moment-when-everyone-become-friends) (Medium)
diff --git a/problems/friend-circles/friend_circles.go b/problems/friend-circles/friend_circles.go
deleted file mode 100644
index 49ade3b03..000000000
--- a/problems/friend-circles/friend_circles.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem547
diff --git a/problems/friend-circles/friend_circles_test.go b/problems/friend-circles/friend_circles_test.go
deleted file mode 100644
index 49ade3b03..000000000
--- a/problems/friend-circles/friend_circles_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem547
diff --git a/problems/friend-requests-i-overall-acceptance-rate/README.md b/problems/friend-requests-i-overall-acceptance-rate/README.md
deleted file mode 100644
index 70e41d79e..000000000
--- a/problems/friend-requests-i-overall-acceptance-rate/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../classes-more-than-5-students "Classes More Than 5 Students")
-　　　　　　　　　　　　　　　　
-[Next >](../range-addition-ii "Range Addition II")
-
-## [597. Friend Requests I: Overall Acceptance Rate (Easy)](https://leetcode.com/problems/friend-requests-i-overall-acceptance-rate "好友申请 I：总体通过率")
-
-In social network like Facebook or Twitter, people send friend requests and accept others&rsquo; requests as well. Now given two tables as below:
-<p>&nbsp;</p>
-Table: <code>friend_request</code>
-
-<pre>
-| sender_id | send_to_id |request_date|
-|-----------|------------|------------|
-| 1         | 2          | 2016_06-01 |
-| 1         | 3          | 2016_06-01 |
-| 1         | 4          | 2016_06-01 |
-| 2         | 3          | 2016_06-02 |
-| 3         | 4          | 2016-06-09 |
-</pre>
-
-<p>&nbsp;</p>
-Table: <code>request_accepted</code>
-
-<pre>
-| requester_id | accepter_id |accept_date |
-|--------------|-------------|------------|
-| 1            | 2           | 2016_06-03 |
-| 1            | 3           | 2016-06-08 |
-| 2            | 3           | 2016-06-08 |
-| 3            | 4           | 2016-06-09 |
-| 3            | 4           | 2016-06-10 |
-</pre>
-
-<p>&nbsp;</p>
-Write a query to find the overall acceptance rate of requests rounded to 2 decimals, which is the number of acceptance divide the number of requests.
-
-<p>&nbsp;</p>
-For the sample data above, your query should return the following result.
-
-<p>&nbsp;</p>
-
-<pre>
-|accept_rate|
-|-----------|
-|       0.80|
-</pre>
-
-<p>&nbsp;</p>
-<b>Note:</b>
-
-<ul>
-	<li>The accepted requests are not necessarily from the table <code>friend_request</code>. In this case, you just need to simply count the total accepted requests (no matter whether they are in the original requests), and divide it by the number of requests to get the acceptance rate.</li>
-	<li>It is possible that a sender sends multiple requests to the same receiver, and a request could be accepted more than once. In this case, the &lsquo;duplicated&rsquo; requests or acceptances are only counted once.</li>
-	<li>If there is no requests at all, you should return 0.00 as the accept_rate.</li>
-</ul>
-
-<p>&nbsp;</p>
-<b>Explanation:</b> There are 4 unique accepted requests, and there are 5 requests in total. So the rate is 0.80.
-
-<p>&nbsp;</p>
-<b>Follow-up:</b>
-
-<ul>
-	<li>Can you write a query to return the accept rate but for every month?</li>
-	<li>How about the cumulative accept rate for every day?</li>
-</ul>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Still remember how to count the number of rows in a table?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What is the keyword to filter the duplicated records in a table?
-</details>
diff --git a/problems/friend-requests-i-overall-acceptance-rate/friend_requests_i_overall_acceptance_rate.sql b/problems/friend-requests-i-overall-acceptance-rate/friend_requests_i_overall_acceptance_rate.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/friend-requests-i-overall-acceptance-rate/friend_requests_i_overall_acceptance_rate.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/friend-requests-i-overall-acceptance-rate/mysql_schemas.sql b/problems/friend-requests-i-overall-acceptance-rate/mysql_schemas.sql
deleted file mode 100644
index c5b60b0ec..000000000
--- a/problems/friend-requests-i-overall-acceptance-rate/mysql_schemas.sql
+++ /dev/null
@@ -1,14 +0,0 @@
-Create table If Not Exists FriendRequest (sender_id int, send_to_id int, request_date date);
-Create table If Not Exists RequestAccepted (requester_id int, accepter_id int, accept_date date);
-Truncate table FriendRequest;
-insert into FriendRequest (sender_id, send_to_id, request_date) values ('1', '2', '2016/06/01');
-insert into FriendRequest (sender_id, send_to_id, request_date) values ('1', '3', '2016/06/01');
-insert into FriendRequest (sender_id, send_to_id, request_date) values ('1', '4', '2016/06/01');
-insert into FriendRequest (sender_id, send_to_id, request_date) values ('2', '3', '2016/06/02');
-insert into FriendRequest (sender_id, send_to_id, request_date) values ('3', '4', '2016/06/09');
-Truncate table RequestAccepted;
-insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('1', '2', '2016/06/03');
-insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('1', '3', '2016/06/08');
-insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('2', '3', '2016/06/08');
-insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('3', '4', '2016/06/09');
-insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('3', '4', '2016/06/10');
diff --git a/problems/friend-requests-ii-who-has-the-most-friends/README.md b/problems/friend-requests-ii-who-has-the-most-friends/README.md
deleted file mode 100644
index fc66fee5a..000000000
--- a/problems/friend-requests-ii-who-has-the-most-friends/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../human-traffic-of-stadium "Human Traffic of Stadium")
-　　　　　　　　　　　　　　　　
-[Next >](../consecutive-available-seats "Consecutive Available Seats")
-
-## [602. Friend Requests II: Who Has the Most Friends (Medium)](https://leetcode.com/problems/friend-requests-ii-who-has-the-most-friends "好友申请 II ：谁有最多的好友")
-
-<p>In social network like Facebook or Twitter, people send friend requests and accept others&#39; requests as well.</p>
-
-<p>&nbsp;</p>
-
-<p>Table <code>request_accepted</code></p>
-
-<pre>
-+--------------+-------------+------------+
-| requester_id | accepter_id | accept_date|
-|--------------|-------------|------------|
-| 1            | 2           | 2016_06-03 |
-| 1            | 3           | 2016-06-08 |
-| 2            | 3           | 2016-06-08 |
-| 3            | 4           | 2016-06-09 |
-+--------------+-------------+------------+
-This table holds the data of friend acceptance, while <b>requester_id</b> and <b>accepter_id</b> both are the id of a person.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write a query to find the the people who has most friends and the most friends number under the following rules:</p>
-
-<ul>
-	<li>It is guaranteed there is only 1 people having the most friends.</li>
-	<li>The friend request could only been accepted once, which mean there is no multiple records with the same <b>requester_id</b> and <b>accepter_id</b> value.</li>
-</ul>
-
-<p>For the sample data above, the result is:</p>
-
-<pre>
-Result table:
-+------+------+
-| id   | num  |
-|------|------|
-| 3    | 3    |
-+------+------+
-The person with id &#39;3&#39; is a friend of people &#39;1&#39;, &#39;2&#39; and &#39;4&#39;, so he has 3 friends in total, which is the most number than any others.
-</pre>
-
-<p><b>Follow-up:</b><br />
-In the real world, multiple people could have the same most number of friends, can you find all these people in this case?</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Being friends is bidirectional. If you accept someone's adding friend request, both you and the other person will have one more friend.
-</details>
diff --git a/problems/friend-requests-ii-who-has-the-most-friends/friend_requests_ii_who_has_the_most_friends.sql b/problems/friend-requests-ii-who-has-the-most-friends/friend_requests_ii_who_has_the_most_friends.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/friend-requests-ii-who-has-the-most-friends/friend_requests_ii_who_has_the_most_friends.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/friend-requests-ii-who-has-the-most-friends/mysql_schemas.sql b/problems/friend-requests-ii-who-has-the-most-friends/mysql_schemas.sql
deleted file mode 100644
index 331165b54..000000000
--- a/problems/friend-requests-ii-who-has-the-most-friends/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists RequestAccepted (requester_id int not null, accepter_id int null, accept_date date null);
-Truncate table RequestAccepted;
-insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('1', '2', '2016/06/03');
-insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('1', '3', '2016/06/08');
-insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('2', '3', '2016/06/08');
-insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('3', '4', '2016/06/09');
diff --git a/problems/friendly-movies-streamed-last-month/README.md b/problems/friendly-movies-streamed-last-month/README.md
deleted file mode 100644
index 406712a31..000000000
--- a/problems/friendly-movies-streamed-last-month/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../parallel-courses-ii "Parallel Courses II")
-　　　　　　　　　　　　　　　　
-[Next >](../path-crossing "Path Crossing")
-
-## [1495. Friendly Movies Streamed Last Month (Easy)](https://leetcode.com/problems/friendly-movies-streamed-last-month "上月播放的儿童适宜电影")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/friendly-movies-streamed-last-month/mysql_schemas.sql b/problems/friendly-movies-streamed-last-month/mysql_schemas.sql
deleted file mode 100644
index 44becd868..000000000
--- a/problems/friendly-movies-streamed-last-month/mysql_schemas.sql
+++ /dev/null
@@ -1,15 +0,0 @@
-Create table If Not Exists TVProgram (program_date date, content_id int, channel varchar(30));
-Create table If Not Exists Content (content_id varchar(30), title varchar(30), Kids_content ENUM('Y', 'N'), content_type varchar(30));
-Truncate table TVProgram;
-insert into TVProgram (program_date, content_id, channel) values ('2020-06-10 08:00', '1', 'LC-Channel');
-insert into TVProgram (program_date, content_id, channel) values ('2020-05-11 12:00', '2', 'LC-Channel');
-insert into TVProgram (program_date, content_id, channel) values ('2020-05-12 12:00', '3', 'LC-Channel');
-insert into TVProgram (program_date, content_id, channel) values ('2020-05-13 14:00', '4', 'Disney Ch');
-insert into TVProgram (program_date, content_id, channel) values ('2020-06-18 14:00', '4', 'Disney Ch');
-insert into TVProgram (program_date, content_id, channel) values ('2020-07-15 16:00', '5', 'Disney Ch');
-Truncate table Content;
-insert into Content (content_id, title, Kids_content, content_type) values ('1', 'Leetcode Movie', 'N', 'Movies');
-insert into Content (content_id, title, Kids_content, content_type) values ('2', 'Alg. for Kids', 'Y', 'Series');
-insert into Content (content_id, title, Kids_content, content_type) values ('3', 'Database Sols', 'N', 'Series');
-insert into Content (content_id, title, Kids_content, content_type) values ('4', 'Aladdin', 'Y', 'Movies');
-insert into Content (content_id, title, Kids_content, content_type) values ('5', 'Cinderella', 'Y', 'Movies');
diff --git a/problems/friends-of-appropriate-ages/README.md b/problems/friends-of-appropriate-ages/README.md
deleted file mode 100644
index 2cb361627..000000000
--- a/problems/friends-of-appropriate-ages/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../goat-latin "Goat Latin")
-　　　　　　　　　　　　　　　　
-[Next >](../most-profit-assigning-work "Most Profit Assigning Work")
-
-## [825. Friends Of Appropriate Ages (Medium)](https://leetcode.com/problems/friends-of-appropriate-ages "适龄的朋友")
-
-<p>There are <code>n</code> persons on a social media website. You are given an integer array <code>ages</code> where <code>ages[i]</code> is the age of the <code>i<sup>th</sup></code> person.</p>
-
-<p>A Person <code>x</code> will not send a friend request to a person <code>y</code> (<code>x != y</code>) if any of the following conditions is true:</p>
-
-<ul>
-	<li><code>age[y] &lt;= 0.5 * age[x] + 7</code></li>
-	<li><code>age[y] &gt; age[x]</code></li>
-	<li><code>age[y] &gt; 100 &amp;&amp; age[x] &lt; 100</code></li>
-</ul>
-
-<p>Otherwise, <code>x</code> will send a friend request to <code>y</code>.</p>
-
-<p>Note that if <code>x</code> sends a request to <code>y</code>, <code>y</code> will not necessarily send a request to <code>x</code>. Also, a person will not send a friend request to themself.</p>
-
-<p>Return <em>the total number of friend requests made</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> ages = [16,16]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 2 people friend request each other.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> ages = [16,17,18]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Friend requests are made 17 -&gt; 16, 18 -&gt; 17.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> ages = [20,30,100,110,120]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Friend requests are made 110 -&gt; 100, 120 -&gt; 110, 120 -&gt; 100.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == ages.length</code></li>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= ages[i] &lt;= 120</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/friends-of-appropriate-ages/friends_of_appropriate_ages.go b/problems/friends-of-appropriate-ages/friends_of_appropriate_ages.go
deleted file mode 100644
index e2eee54cc..000000000
--- a/problems/friends-of-appropriate-ages/friends_of_appropriate_ages.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem825
diff --git a/problems/friends-of-appropriate-ages/friends_of_appropriate_ages_test.go b/problems/friends-of-appropriate-ages/friends_of_appropriate_ages_test.go
deleted file mode 100644
index e2eee54cc..000000000
--- a/problems/friends-of-appropriate-ages/friends_of_appropriate_ages_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem825
diff --git a/problems/frog-jump/README.md b/problems/frog-jump/README.md
deleted file mode 100644
index 25614c52b..000000000
--- a/problems/frog-jump/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-k-digits "Remove K Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-left-leaves "Sum of Left Leaves")
-
-## [403. Frog Jump (Hard)](https://leetcode.com/problems/frog-jump "青蛙过河")
-
-<p>A frog is crossing a river. The river is divided into some number of units, and at each unit, there may or may not exist a stone. The frog can jump on a stone, but it must not jump into the water.</p>
-
-<p>Given a list of <code>stones</code>&#39; positions (in units) in sorted <strong>ascending order</strong>, determine if the frog can cross the river by landing on the last stone. Initially, the frog is on the first stone and assumes the first jump must be <code>1</code> unit.</p>
-
-<p>If the frog&#39;s last jump was <code>k</code> units, its next jump must be either <code>k - 1</code>, <code>k</code>, or <code>k + 1</code> units. The frog can only jump in the forward direction.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [0,1,3,5,6,8,12,17]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The frog can jump to the last stone by jumping 1 unit to the 2nd stone, then 2 units to the 3rd stone, then 2 units to the 4th stone, then 3 units to the 6th stone, 4 units to the 7th stone, and 5 units to the 8th stone.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [0,1,2,3,4,8,9,11]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There is no way to jump to the last stone as the gap between the 5th and 6th stone is too large.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= stones.length &lt;= 2000</code></li>
-	<li><code>0 &lt;= stones[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>stones[0] == 0</code></li>
-	<li><code>stones</code>&nbsp;is sorted in a strictly increasing order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/frog-jump/frog_jump.go b/problems/frog-jump/frog_jump.go
deleted file mode 100644
index 816b09908..000000000
--- a/problems/frog-jump/frog_jump.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem403
diff --git a/problems/frog-jump/frog_jump_test.go b/problems/frog-jump/frog_jump_test.go
deleted file mode 100644
index 816b09908..000000000
--- a/problems/frog-jump/frog_jump_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem403
diff --git a/problems/frog-position-after-t-seconds/README.md b/problems/frog-position-after-t-seconds/README.md
deleted file mode 100644
index 1e6ecd7bf..000000000
--- a/problems/frog-position-after-t-seconds/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../time-needed-to-inform-all-employees "Time Needed to Inform All Employees")
-　　　　　　　　　　　　　　　　
-[Next >](../replace-employee-id-with-the-unique-identifier "Replace Employee ID With The Unique Identifier")
-
-## [1377. Frog Position After T Seconds (Hard)](https://leetcode.com/problems/frog-position-after-t-seconds "T 秒后青蛙的位置")
-
-<p>Given an undirected tree consisting of <code>n</code> vertices numbered from <code>1</code> to <code>n</code>. A frog starts jumping from <strong>vertex 1</strong>. In one second, the frog jumps from its current vertex to another <strong>unvisited</strong> vertex if they are directly connected. The frog can not jump back to a visited vertex. In case the frog can jump to several vertices, it jumps randomly to one of them with the same probability. Otherwise, when the frog can not jump to any unvisited vertex, it jumps forever on the same vertex.</p>
-
-<p>The edges of the undirected tree are given in the array <code>edges</code>, where <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> means that exists an edge connecting the vertices <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code>.</p>
-
-<p><em>Return the probability that after <code>t</code> seconds the frog is on the vertex <code>target</code>. </em>Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/21/frog1.jpg" style="width: 338px; height: 304px;" />
-<pre>
-<strong>Input:</strong> n = 7, edges = [[1,2],[1,3],[1,7],[2,4],[2,6],[3,5]], t = 2, target = 4
-<strong>Output:</strong> 0.16666666666666666 
-<strong>Explanation:</strong> The figure above shows the given graph. The frog starts at vertex 1, jumping with 1/3 probability to the vertex 2 after <strong>second 1</strong> and then jumping with 1/2 probability to vertex 4 after <strong>second 2</strong>. Thus the probability for the frog is on the vertex 4 after 2 seconds is 1/3 * 1/2 = 1/6 = 0.16666666666666666. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<strong><img alt="" src="https://assets.leetcode.com/uploads/2021/12/21/frog2.jpg" style="width: 304px; height: 304px;" /></strong>
-
-<pre>
-<strong>Input:</strong> n = 7, edges = [[1,2],[1,3],[1,7],[2,4],[2,6],[3,5]], t = 1, target = 7
-<strong>Output:</strong> 0.3333333333333333
-<strong>Explanation: </strong>The figure above shows the given graph. The frog starts at vertex 1, jumping with 1/3 = 0.3333333333333333 probability to the vertex 7 after <strong>second 1</strong>. 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>edges.length == n - 1</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>1 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt;= n</code></li>
-	<li><code>1 &lt;= t &lt;= 50</code></li>
-	<li><code>1 &lt;= target &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a variation of DFS with parameters 'curent_vertex' and 'current_time'.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Update the probability considering to jump to one of the children vertices.
-</details>
diff --git a/problems/fruit-into-baskets/README.md b/problems/fruit-into-baskets/README.md
deleted file mode 100644
index e4961b828..000000000
--- a/problems/fruit-into-baskets/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-permutations-for-di-sequence "Valid Permutations for DI Sequence")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-array-by-parity "Sort Array By Parity")
-
-## [904. Fruit Into Baskets (Medium)](https://leetcode.com/problems/fruit-into-baskets "水果成篮")
-
-<p>You are visiting a farm that has a single row of fruit trees arranged from left to right. The trees are represented by an integer array <code>fruits</code> where <code>fruits[i]</code> is the <strong>type</strong> of fruit the <code>i<sup>th</sup></code> tree produces.</p>
-
-<p>You want to collect as much fruit as possible. However, the owner has some strict rules that you must follow:</p>
-
-<ul>
-	<li>You only have <strong>two</strong> baskets, and each basket can only hold a <strong>single type</strong> of fruit. There is no limit on the amount of fruit each basket can hold.</li>
-	<li>Starting from any tree of your choice, you must pick <strong>exactly one fruit</strong> from <strong>every</strong> tree (including the start tree) while moving to the right. The picked fruits must fit in one of your baskets.</li>
-	<li>Once you reach a tree with fruit that cannot fit in your baskets, you must stop.</li>
-</ul>
-
-<p>Given the integer array <code>fruits</code>, return <em>the <strong>maximum</strong> number of fruits you can pick</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> fruits = [<u>1,2,1</u>]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We can pick from all 3 trees.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> fruits = [0,<u>1,2,2</u>]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We can pick from trees [1,2,2].
-If we had started at the first tree, we would only pick from trees [0,1].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> fruits = [1,<u>2,3,2,2</u>]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> We can pick from trees [2,3,2,2].
-If we had started at the first tree, we would only pick from trees [1,2].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= fruits.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= fruits[i] &lt; fruits.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
diff --git a/problems/fruit-into-baskets/fruit_into_baskets.go b/problems/fruit-into-baskets/fruit_into_baskets.go
deleted file mode 100644
index 2f71a64dd..000000000
--- a/problems/fruit-into-baskets/fruit_into_baskets.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem904
diff --git a/problems/fruit-into-baskets/fruit_into_baskets_test.go b/problems/fruit-into-baskets/fruit_into_baskets_test.go
deleted file mode 100644
index 2f71a64dd..000000000
--- a/problems/fruit-into-baskets/fruit_into_baskets_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem904
diff --git a/problems/furthest-building-you-can-reach/README.md b/problems/furthest-building-you-can-reach/README.md
deleted file mode 100644
index 0eb1d71a5..000000000
--- a/problems/furthest-building-you-can-reach/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-sorted-vowel-strings "Count Sorted Vowel Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-smallest-instructions "Kth Smallest Instructions")
-
-## [1642. Furthest Building You Can Reach (Medium)](https://leetcode.com/problems/furthest-building-you-can-reach "可以到达的最远建筑")
-
-<p>You are given an integer array <code>heights</code> representing the heights of buildings, some <code>bricks</code>, and some <code>ladders</code>.</p>
-
-<p>You start your journey from building <code>0</code> and move to the next building by possibly using bricks or ladders.</p>
-
-<p>While moving from building <code>i</code> to building <code>i+1</code> (<strong>0-indexed</strong>),</p>
-
-<ul>
-	<li>If the current building&#39;s height is <strong>greater than or equal</strong> to the next building&#39;s height, you do <strong>not</strong> need a ladder or bricks.</li>
-	<li>If the current building&#39;s height is <b>less than</b> the next building&#39;s height, you can either use <strong>one ladder</strong> or <code>(h[i+1] - h[i])</code> <strong>bricks</strong>.</li>
-</ul>
-
-<p><em>Return the furthest building index (0-indexed) you can reach if you use the given ladders and bricks optimally.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/27/q4.gif" style="width: 562px; height: 561px;" />
-<pre>
-<strong>Input:</strong> heights = [4,2,7,6,9,14,12], bricks = 5, ladders = 1
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Starting at building 0, you can follow these steps:
-- Go to building 1 without using ladders nor bricks since 4 &gt;= 2.
-- Go to building 2 using 5 bricks. You must use either bricks or ladders because 2 &lt; 7.
-- Go to building 3 without using ladders nor bricks since 7 &gt;= 6.
-- Go to building 4 using your only ladder. You must use either bricks or ladders because 6 &lt; 9.
-It is impossible to go beyond building 4 because you do not have any more bricks or ladders.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> heights = [4,12,2,7,3,18,20,3,19], bricks = 10, ladders = 2
-<strong>Output:</strong> 7
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> heights = [14,3,19,3], bricks = 17, ladders = 0
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= heights.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= heights[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>0 &lt;= bricks &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= ladders &lt;= heights.length</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Assume the problem is to check whether you can reach the last building or not.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You'll have to do a set of jumps, and choose for each one whether to do it using a ladder or bricks. It's always optimal to use ladders in the largest jumps.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Iterate on the buildings, maintaining the largest r jumps and the sum of the remaining ones so far, and stop whenever this sum exceeds b.
-</details>
diff --git a/problems/game-of-life/README.md b/problems/game-of-life/README.md
deleted file mode 100644
index 1353108f0..000000000
--- a/problems/game-of-life/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-word-abbreviation "Unique Word Abbreviation")
-　　　　　　　　　　　　　　　　
-[Next >](../word-pattern "Word Pattern")
-
-## [289. Game of Life (Medium)](https://leetcode.com/problems/game-of-life "生命游戏")
-
-<p>According to&nbsp;<a href="https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life" target="_blank">Wikipedia&#39;s article</a>: &quot;The <b>Game of Life</b>, also known simply as <b>Life</b>, is a cellular automaton devised by the British mathematician John Horton Conway in 1970.&quot;</p>
-
-<p>The board is made up of an <code>m x n</code> grid of cells, where each cell has an initial state: <b>live</b> (represented by a <code>1</code>) or <b>dead</b> (represented by a <code>0</code>). Each cell interacts with its <a href="https://en.wikipedia.org/wiki/Moore_neighborhood" target="_blank">eight neighbors</a> (horizontal, vertical, diagonal) using the following four rules (taken from the above Wikipedia article):</p>
-
-<ol>
-	<li>Any live cell with fewer than two live neighbors dies as if caused by under-population.</li>
-	<li>Any live cell with two or three live neighbors lives on to the next generation.</li>
-	<li>Any live cell with more than three live neighbors dies, as if by over-population.</li>
-	<li>Any dead cell with exactly three live neighbors becomes a live cell, as if by reproduction.</li>
-</ol>
-
-<p><span>The next state is created by applying the above rules simultaneously to every cell in the current state, where births and deaths occur simultaneously. Given the current state of the <code>m x n</code> grid <code>board</code>, return <em>the next state</em>.</span></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/26/grid1.jpg" style="width: 562px; height: 322px;" />
-<pre>
-<strong>Input:</strong> board = [[0,1,0],[0,0,1],[1,1,1],[0,0,0]]
-<strong>Output:</strong> [[0,0,0],[1,0,1],[0,1,1],[0,1,0]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/26/grid2.jpg" style="width: 402px; height: 162px;" />
-<pre>
-<strong>Input:</strong> board = [[1,1],[1,0]]
-<strong>Output:</strong> [[1,1],[1,1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == board.length</code></li>
-	<li><code>n == board[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 25</code></li>
-	<li><code>board[i][j]</code> is <code>0</code> or <code>1</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>Could you solve it in-place? Remember that the board needs to be updated simultaneously: You cannot update some cells first and then use their updated values to update other cells.</li>
-	<li>In this question, we represent the board using a 2D array. In principle, the board is infinite, which would cause problems when the active area encroaches upon the border of the array (i.e., live cells reach the border). How would you address these problems?</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Set Matrix Zeroes](../set-matrix-zeroes) (Medium)
diff --git a/problems/game-of-life/game_of_life.go b/problems/game-of-life/game_of_life.go
deleted file mode 100644
index 1efaa79ca..000000000
--- a/problems/game-of-life/game_of_life.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem289
diff --git a/problems/game-of-life/game_of_life_test.go b/problems/game-of-life/game_of_life_test.go
deleted file mode 100644
index 1efaa79ca..000000000
--- a/problems/game-of-life/game_of_life_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem289
diff --git a/problems/game-of-nim/README.md b/problems/game-of-nim/README.md
deleted file mode 100644
index fcbf6020d..000000000
--- a/problems/game-of-nim/README.md
+++ /dev/null
@@ -1,28 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-salary-categories "Count Salary Categories")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-one-element-to-make-the-array-strictly-increasing "Remove One Element to Make the Array Strictly Increasing")
-
-## [1908. Game of Nim (Medium)](https://leetcode.com/problems/game-of-nim "Nim 游戏 II")
-
-
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Brainteaser](../../tag/brainteaser/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the game and try all possible moves for each player.
-</details>
diff --git a/problems/game-play-analysis-i/README.md b/problems/game-play-analysis-i/README.md
deleted file mode 100644
index 5fccd1c99..000000000
--- a/problems/game-play-analysis-i/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../inorder-successor-in-bst-ii "Inorder Successor in BST II")
-　　　　　　　　　　　　　　　　
-[Next >](../game-play-analysis-ii "Game Play Analysis II")
-
-## [511. Game Play Analysis I (Easy)](https://leetcode.com/problems/game-play-analysis-i "游戏玩法分析 I")
-
-<p>Table:&nbsp;<code>Activity</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| player_id    | int     |
-| device_id    | int     |
-| event_date   | date    |
-| games_played | int     |
-+--------------+---------+
-(player_id, event_date) is the primary key of this table.
-This table shows the activity of players of some game.
-Each row is a record of a player who logged in and played a number of games (possibly 0) before logging out on some day using some device.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the&nbsp;<strong>first login date</strong> for each player.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Activity table:
-+-----------+-----------+------------+--------------+
-| player_id | device_id | event_date | games_played |
-+-----------+-----------+------------+--------------+
-| 1         | 2         | 2016-03-01 | 5            |
-| 1         | 2         | 2016-05-02 | 6            |
-| 2         | 3         | 2017-06-25 | 1            |
-| 3         | 1         | 2016-03-02 | 0            |
-| 3         | 4         | 2018-07-03 | 5            |
-+-----------+-----------+------------+--------------+
-
-Result table:
-+-----------+-------------+
-| player_id | first_login |
-+-----------+-------------+
-| 1         | 2016-03-01  |
-| 2         | 2017-06-25  |
-| 3         | 2016-03-02  |
-+-----------+-------------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Game Play Analysis II](../game-play-analysis-ii) (Easy)
diff --git a/problems/game-play-analysis-i/game_play_analysis_i.sql b/problems/game-play-analysis-i/game_play_analysis_i.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/game-play-analysis-i/game_play_analysis_i.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/game-play-analysis-i/mysql_schemas.sql b/problems/game-play-analysis-i/mysql_schemas.sql
deleted file mode 100644
index 519a7e42c..000000000
--- a/problems/game-play-analysis-i/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Activity (player_id int, device_id int, event_date date, games_played int);
-Truncate table Activity;
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-03-01', '5');
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-05-02', '6');
-insert into Activity (player_id, device_id, event_date, games_played) values ('2', '3', '2017-06-25', '1');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '1', '2016-03-02', '0');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '4', '2018-07-03', '5');
diff --git a/problems/game-play-analysis-ii/README.md b/problems/game-play-analysis-ii/README.md
deleted file mode 100644
index d71bce674..000000000
--- a/problems/game-play-analysis-ii/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../game-play-analysis-i "Game Play Analysis I")
-　　　　　　　　　　　　　　　　
-[Next >](../find-bottom-left-tree-value "Find Bottom Left Tree Value")
-
-## [512. Game Play Analysis II (Easy)](https://leetcode.com/problems/game-play-analysis-ii "游戏玩法分析 II")
-
-<p>Table:&nbsp;<code>Activity</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| player_id    | int     |
-| device_id    | int     |
-| event_date   | date    |
-| games_played | int     |
-+--------------+---------+
-(player_id, event_date) is the primary key of this table.
-This table shows the activity of players of some game.
-Each row is a record of a player who logged in and played a number of games (possibly 0) before logging out on some day using some device.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write a&nbsp;SQL query that reports&nbsp;the <strong>device</strong>&nbsp;that is first logged in&nbsp;for each player.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Activity table:
-+-----------+-----------+------------+--------------+
-| player_id | device_id | event_date | games_played |
-+-----------+-----------+------------+--------------+
-| 1         | 2         | 2016-03-01 | 5            |
-| 1         | 2         | 2016-05-02 | 6            |
-| 2         | 3         | 2017-06-25 | 1            |
-| 3         | 1         | 2016-03-02 | 0            |
-| 3         | 4         | 2018-07-03 | 5            |
-+-----------+-----------+------------+--------------+
-
-Result table:
-+-----------+-----------+
-| player_id | device_id |
-+-----------+-----------+
-| 1         | 2         |
-| 2         | 3         |
-| 3         | 1         |
-+-----------+-----------+</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Game Play Analysis I](../game-play-analysis-i) (Easy)
-  1. [Game Play Analysis III](../game-play-analysis-iii) (Medium)
diff --git a/problems/game-play-analysis-ii/game_play_analysis_ii.sql b/problems/game-play-analysis-ii/game_play_analysis_ii.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/game-play-analysis-ii/game_play_analysis_ii.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/game-play-analysis-ii/mysql_schemas.sql b/problems/game-play-analysis-ii/mysql_schemas.sql
deleted file mode 100644
index 519a7e42c..000000000
--- a/problems/game-play-analysis-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Activity (player_id int, device_id int, event_date date, games_played int);
-Truncate table Activity;
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-03-01', '5');
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-05-02', '6');
-insert into Activity (player_id, device_id, event_date, games_played) values ('2', '3', '2017-06-25', '1');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '1', '2016-03-02', '0');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '4', '2018-07-03', '5');
diff --git a/problems/game-play-analysis-iii/README.md b/problems/game-play-analysis-iii/README.md
deleted file mode 100644
index 27f77f9b4..000000000
--- a/problems/game-play-analysis-iii/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lonely-pixel-ii "Lonely Pixel II")
-　　　　　　　　　　　　　　　　
-[Next >](../encode-and-decode-tinyurl "Encode and Decode TinyURL")
-
-## [534. Game Play Analysis III (Medium)](https://leetcode.com/problems/game-play-analysis-iii "游戏玩法分析 III")
-
-<p>Table:&nbsp;<code>Activity</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| player_id    | int     |
-| device_id    | int     |
-| event_date   | date    |
-| games_played | int     |
-+--------------+---------+
-(player_id, event_date) is the primary key of this table.
-This table shows the activity of players of some game.
-Each row is a record of a player who logged in and played a number of games (possibly 0) before logging out on some day using some device.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports for each player and date, how many games played&nbsp;<strong>so far</strong>&nbsp;by the player. That is, the total number of games played by the player until that date. Check the example for clarity.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Activity table:
-+-----------+-----------+------------+--------------+
-| player_id | device_id | event_date | games_played |
-+-----------+-----------+------------+--------------+
-| 1         | 2         | 2016-03-01 | 5            |
-| 1         | 2         | 2016-05-02 | 6            |
-| 1         | 3         | 2017-06-25 | 1            |
-| 3         | 1         | 2016-03-02 | 0            |
-| 3         | 4         | 2018-07-03 | 5            |
-+-----------+-----------+------------+--------------+
-
-Result table:
-+-----------+------------+---------------------+
-| player_id | event_date | games_played_so_far |
-+-----------+------------+---------------------+
-| 1         | 2016-03-01 | 5                   |
-| 1         | 2016-05-02 | 11                  |
-| 1         | 2017-06-25 | 12                  |
-| 3         | 2016-03-02 | 0                   |
-| 3         | 2018-07-03 | 5                   |
-+-----------+------------+---------------------+
-For the player with id 1, 5 + 6 = 11 games played by 2016-05-02, and 5 + 6 + 1 = 12 games played by 2017-06-25.
-For the player with id 3, 0 + 5 = 5 games played by 2018-07-03.
-Note that for each player we only care about the days when the player logged in.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Game Play Analysis II](../game-play-analysis-ii) (Easy)
-  1. [Game Play Analysis IV](../game-play-analysis-iv) (Medium)
diff --git a/problems/game-play-analysis-iii/game_play_analysis_iii.sql b/problems/game-play-analysis-iii/game_play_analysis_iii.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/game-play-analysis-iii/game_play_analysis_iii.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/game-play-analysis-iii/mysql_schemas.sql b/problems/game-play-analysis-iii/mysql_schemas.sql
deleted file mode 100644
index cb1a27f6d..000000000
--- a/problems/game-play-analysis-iii/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Activity (player_id int, device_id int, event_date date, games_played int);
-Truncate table Activity;
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-03-01', '5');
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-05-02', '6');
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '3', '2017-06-25', '1');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '1', '2016-03-02', '0');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '4', '2018-07-03', '5');
diff --git a/problems/game-play-analysis-iv/README.md b/problems/game-play-analysis-iv/README.md
deleted file mode 100644
index 78c3fc2e1..000000000
--- a/problems/game-play-analysis-iv/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-longest-consecutive-sequence-ii "Binary Tree Longest Consecutive Sequence II")
-　　　　　　　　　　　　　　　　
-[Next >](../student-attendance-record-i "Student Attendance Record I")
-
-## [550. Game Play Analysis IV (Medium)](https://leetcode.com/problems/game-play-analysis-iv "游戏玩法分析 IV")
-
-<p>Table:&nbsp;<code>Activity</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| player_id    | int     |
-| device_id    | int     |
-| event_date   | date    |
-| games_played | int     |
-+--------------+---------+
-(player_id, event_date) is the primary key of this table.
-This table shows the activity of players of some game.
-Each row is a record of a player who logged in and played a number of games (possibly 0) before logging out on some day using some device.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the <strong>fraction</strong> of players that logged in again on the day after the day they first logged in,&nbsp;<strong>rounded to 2 decimal places</strong>.&nbsp;In other words, you need to count the number of players that logged in for at least two consecutive days starting from their first login date, then divide that number by the total number of players.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Activity table:
-+-----------+-----------+------------+--------------+
-| player_id | device_id | event_date | games_played |
-+-----------+-----------+------------+--------------+
-| 1         | 2         | 2016-03-01 | 5            |
-| 1         | 2         | 2016-03-02 | 6            |
-| 2         | 3         | 2017-06-25 | 1            |
-| 3         | 1         | 2016-03-02 | 0            |
-| 3         | 4         | 2018-07-03 | 5            |
-+-----------+-----------+------------+--------------+
-
-Result table:
-+-----------+
-| fraction  |
-+-----------+
-| 0.33      |
-+-----------+
-Only the player with id 1 logged back in after the first day he had logged in so the answer is 1/3 = 0.33
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Game Play Analysis III](../game-play-analysis-iii) (Medium)
-  1. [Game Play Analysis V](../game-play-analysis-v) (Hard)
diff --git a/problems/game-play-analysis-iv/game_play_analysis_iv.sql b/problems/game-play-analysis-iv/game_play_analysis_iv.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/game-play-analysis-iv/game_play_analysis_iv.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/game-play-analysis-iv/mysql_schemas.sql b/problems/game-play-analysis-iv/mysql_schemas.sql
deleted file mode 100644
index 19191e384..000000000
--- a/problems/game-play-analysis-iv/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Activity (player_id int, device_id int, event_date date, games_played int);
-Truncate table Activity;
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-03-01', '5');
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-03-02', '6');
-insert into Activity (player_id, device_id, event_date, games_played) values ('2', '3', '2017-06-25', '1');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '1', '2016-03-02', '0');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '4', '2018-07-03', '5');
diff --git a/problems/game-play-analysis-v/README.md b/problems/game-play-analysis-v/README.md
deleted file mode 100644
index 6de3e4488..000000000
--- a/problems/game-play-analysis-v/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../brace-expansion-ii "Brace Expansion II")
-　　　　　　　　　　　　　　　　
-[Next >](../unpopular-books "Unpopular Books")
-
-## [1097. Game Play Analysis V (Hard)](https://leetcode.com/problems/game-play-analysis-v "游戏玩法分析 V")
-
-<p>Table:&nbsp;<code>Activity</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| player_id    | int     |
-| device_id    | int     |
-| event_date   | date    |
-| games_played | int     |
-+--------------+---------+
-(player_id, event_date) is the primary key of this table.
-This table shows the activity of players of some game.
-Each row is a record of a player who logged in and played a number of games (possibly 0) before logging out on some day using some device.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>We define the <em>install date</em> of a player to be the first login day of that player.</p>
-
-<p>We also define <em>day 1 retention</em>&nbsp;of some date <code>X</code>&nbsp;to be the number&nbsp;of players whose install date is&nbsp;<code>X</code>&nbsp;and they logged back in on the day right after <code>X</code>, divided by the number of players whose install date is&nbsp;<code>X</code>, <strong>rounded to 2 decimal places</strong>.</p>
-
-<p>Write an SQL query that reports for each <strong>install date</strong>, the <strong>number&nbsp;of players</strong> that installed the game on that day and the <strong>day 1 retention</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Activity table:
-+-----------+-----------+------------+--------------+
-| player_id | device_id | event_date | games_played |
-+-----------+-----------+------------+--------------+
-| 1         | 2         | 2016-03-01 | 5            |
-| 1         | 2         | 2016-03-02 | 6            |
-| 2         | 3         | 2017-06-25 | 1            |
-| 3         | 1         | 2016-03-01 | 0            |
-| 3         | 4         | 2016-07-03 | 5            |
-+-----------+-----------+------------+--------------+
-
-Result table:
-+------------+----------+----------------+
-| install_dt | installs | Day1_retention |
-+------------+----------+----------------+
-| 2016-03-01 | 2        | 0.50           |
-| 2017-06-25 | 1        | 0.00           |
-+------------+----------+----------------+
-Player 1 and 3 installed the game on 2016-03-01 but only player 1 logged back in on 2016-03-02 so the day 1 retention of 2016-03-01 is 1 / 2 = 0.50
-Player 2 installed the game on 2017-06-25 but didn&#39;t log back in on 2017-06-26 so the day 1 retention of 2017-06-25 is 0 / 1 = 0.00
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Game Play Analysis IV](../game-play-analysis-iv) (Medium)
diff --git a/problems/game-play-analysis-v/game_play_analysis_v.sql b/problems/game-play-analysis-v/game_play_analysis_v.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/game-play-analysis-v/game_play_analysis_v.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/game-play-analysis-v/mysql_schemas.sql b/problems/game-play-analysis-v/mysql_schemas.sql
deleted file mode 100644
index 0ffb69b00..000000000
--- a/problems/game-play-analysis-v/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Activity (player_id int, device_id int, event_date date, games_played int);
-Truncate table Activity;
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-03-01', '5');
-insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-03-02', '6');
-insert into Activity (player_id, device_id, event_date, games_played) values ('2', '3', '2017-06-25', '1');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '1', '2016-03-01', '0');
-insert into Activity (player_id, device_id, event_date, games_played) values ('3', '4', '2018-07-03', '5');
diff --git a/problems/gas-station/README.md b/problems/gas-station/README.md
deleted file mode 100644
index be07ba5dd..000000000
--- a/problems/gas-station/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../clone-graph "Clone Graph")
-　　　　　　　　　　　　　　　　
-[Next >](../candy "Candy")
-
-## [134. Gas Station (Medium)](https://leetcode.com/problems/gas-station "加油站")
-
-<p>There are <code>n</code> gas stations along a circular route, where the amount of gas at the <code>i<sup>th</sup></code> station is <code>gas[i]</code>.</p>
-
-<p>You have a car with an unlimited gas tank and it costs <code>cost[i]</code> of gas to travel from the <code>i<sup>th</sup></code> station to its next <code>(i + 1)<sup>th</sup></code> station. You begin the journey with an empty tank at one of the gas stations.</p>
-
-<p>Given two integer arrays <code>gas</code> and <code>cost</code>, return <em>the starting gas station&#39;s index if you can travel around the circuit once in the clockwise direction, otherwise return</em> <code>-1</code>. If there exists a solution, it is <strong>guaranteed</strong> to be <strong>unique</strong></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> gas = [1,2,3,4,5], cost = [3,4,5,1,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-Start at station 3 (index 3) and fill up with 4 unit of gas. Your tank = 0 + 4 = 4
-Travel to station 4. Your tank = 4 - 1 + 5 = 8
-Travel to station 0. Your tank = 8 - 2 + 1 = 7
-Travel to station 1. Your tank = 7 - 3 + 2 = 6
-Travel to station 2. Your tank = 6 - 4 + 3 = 5
-Travel to station 3. The cost is 5. Your gas is just enough to travel back to station 3.
-Therefore, return 3 as the starting index.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> gas = [2,3,4], cost = [3,4,3]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>
-You can&#39;t start at station 0 or 1, as there is not enough gas to travel to the next station.
-Let&#39;s start at station 2 and fill up with 4 unit of gas. Your tank = 0 + 4 = 4
-Travel to station 0. Your tank = 4 - 3 + 2 = 3
-Travel to station 1. Your tank = 3 - 3 + 3 = 3
-You cannot travel back to station 2, as it requires 4 unit of gas but you only have 3.
-Therefore, you can&#39;t travel around the circuit once no matter where you start.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>gas.length == n</code></li>
-	<li><code>cost.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= gas[i], cost[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
diff --git a/problems/gas-station/gas_station.go b/problems/gas-station/gas_station.go
deleted file mode 100644
index 209fb0c3e..000000000
--- a/problems/gas-station/gas_station.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem134
diff --git a/problems/gas-station/gas_station_test.go b/problems/gas-station/gas_station_test.go
deleted file mode 100644
index 209fb0c3e..000000000
--- a/problems/gas-station/gas_station_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem134
diff --git a/problems/gcd-sort-of-an-array/README.md b/problems/gcd-sort-of-an-array/README.md
deleted file mode 100644
index 963bb3455..000000000
--- a/problems/gcd-sort-of-an-array/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../first-day-where-you-have-been-in-all-the-rooms "First Day Where You Have Been in All the Rooms")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-greater-multiple-made-of-two-digits "Smallest Greater Multiple Made of Two Digits")
-
-## [1998. GCD Sort of an Array (Hard)](https://leetcode.com/problems/gcd-sort-of-an-array "数组的最大公因数排序")
-
-<p>You are given an integer array <code>nums</code>, and you can perform the following operation <strong>any</strong> number of times on <code>nums</code>:</p>
-
-<ul>
-	<li>Swap the positions of two elements <code>nums[i]</code> and <code>nums[j]</code> if <code>gcd(nums[i], nums[j]) &gt; 1</code> where <code>gcd(nums[i], nums[j])</code> is the <strong>greatest common divisor</strong> of <code>nums[i]</code> and <code>nums[j]</code>.</li>
-</ul>
-
-<p>Return <code>true</code> <em>if it is possible to sort </em><code>nums</code><em> in <strong>non-decreasing</strong> order using the above swap method, or </em><code>false</code><em> otherwise.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,21,3]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We can sort [7,21,3] by performing the following operations:
-- Swap 7 and 21 because gcd(7,21) = 7. nums = [<u><strong>21</strong></u>,<u><strong>7</strong></u>,3]
-- Swap 21 and 3 because gcd(21,3) = 3. nums = [<u><strong>3</strong></u>,7,<u><strong>21</strong></u>]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,2,6,2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to sort the array because 5 cannot be swapped with any other element.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,5,9,3,15]
-<strong>Output:</strong> true
-We can sort [10,5,9,3,15] by performing the following operations:
-- Swap 10 and 15 because gcd(10,15) = 5. nums = [<u><strong>15</strong></u>,5,9,3,<u><strong>10</strong></u>]
-- Swap 15 and 3 because gcd(15,3) = 3. nums = [<u><strong>3</strong></u>,5,9,<u><strong>15</strong></u>,10]
-- Swap 10 and 15 because gcd(10,15) = 5. nums = [3,5,9,<u><strong>10</strong></u>,<u><strong>15</strong></u>]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>2 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we build a graph with all the prime numbers and the original array?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can use union-find to determine which indices are connected (i.e., which indices can be swapped).
-</details>
diff --git a/problems/generalized-abbreviation/README.md b/problems/generalized-abbreviation/README.md
deleted file mode 100644
index 017a197f6..000000000
--- a/problems/generalized-abbreviation/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bulb-switcher "Bulb Switcher")
-　　　　　　　　　　　　　　　　
-[Next >](../create-maximum-number "Create Maximum Number")
-
-## [320. Generalized Abbreviation (Medium)](https://leetcode.com/problems/generalized-abbreviation "列举单词的全部缩写")
-
-<p>Write a function to generate the generalized abbreviations of a word.&nbsp;</p>
-
-<p><strong>Note:&nbsp;</strong>The order of the output does not matter.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-<strong>Input:</strong> <code>&quot;word&quot;</code>
-<strong>Output:</strong>
-[&quot;word&quot;, &quot;1ord&quot;, &quot;w1rd&quot;, &quot;wo1d&quot;, &quot;wor1&quot;, &quot;2rd&quot;, &quot;w2d&quot;, &quot;wo2&quot;, &quot;1o1d&quot;, &quot;1or1&quot;, &quot;w1r1&quot;, &quot;1o2&quot;, &quot;2r1&quot;, &quot;3d&quot;, &quot;w3&quot;, &quot;4&quot;]
-</pre>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Subsets](../subsets) (Medium)
-  1. [Unique Word Abbreviation](../unique-word-abbreviation) (Medium)
-  1. [Minimum Unique Word Abbreviation](../minimum-unique-word-abbreviation) (Hard)
diff --git a/problems/generalized-abbreviation/generalized_abbreviation.go b/problems/generalized-abbreviation/generalized_abbreviation.go
deleted file mode 100644
index aa0bcaa6d..000000000
--- a/problems/generalized-abbreviation/generalized_abbreviation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem320
diff --git a/problems/generalized-abbreviation/generalized_abbreviation_test.go b/problems/generalized-abbreviation/generalized_abbreviation_test.go
deleted file mode 100644
index aa0bcaa6d..000000000
--- a/problems/generalized-abbreviation/generalized_abbreviation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem320
diff --git a/problems/generate-a-string-with-characters-that-have-odd-counts/README.md b/problems/generate-a-string-with-characters-that-have-odd-counts/README.md
deleted file mode 100644
index f92d2f599..000000000
--- a/problems/generate-a-string-with-characters-that-have-odd-counts/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-sum-bst-in-binary-tree "Maximum Sum BST in Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../bulb-switcher-iii "Bulb Switcher III")
-
-## [1374. Generate a String With Characters That Have Odd Counts (Easy)](https://leetcode.com/problems/generate-a-string-with-characters-that-have-odd-counts "生成每种字符都是奇数个的字符串")
-
-<p>Given an&nbsp;integer <code>n</code>, <em>return a string with <code>n</code>&nbsp;characters such that each character in such string occurs <strong>an odd number of times</strong></em>.</p>
-
-<p>The returned string must contain only lowercase English letters. If there are multiples valid strings, return <strong>any</strong> of them. &nbsp;</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> &quot;pppz&quot;
-<strong>Explanation:</strong> &quot;pppz&quot; is a valid string since the character &#39;p&#39; occurs three times and the character &#39;z&#39; occurs once. Note that there are many other valid strings such as &quot;ohhh&quot; and &quot;love&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> &quot;xy&quot;
-<strong>Explanation:</strong> &quot;xy&quot; is a valid string since the characters &#39;x&#39; and &#39;y&#39; occur once. Note that there are many other valid strings such as &quot;ag&quot; and &quot;ur&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7
-<strong>Output:</strong> &quot;holasss&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If n is odd, return a string of size n formed only by 'a', else return string formed with n-1 'a' and 1 'b''.
-</details>
diff --git a/problems/generate-a-string-with-characters-that-have-odd-counts/generate_a_string_with_characters_that_have_odd_counts.go b/problems/generate-a-string-with-characters-that-have-odd-counts/generate_a_string_with_characters_that_have_odd_counts.go
deleted file mode 100644
index 707bfb46d..000000000
--- a/problems/generate-a-string-with-characters-that-have-odd-counts/generate_a_string_with_characters_that_have_odd_counts.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem1374
-
-func generateTheString(n int) string {
-	b := make([]byte, n)
-	for i := 0; i < n; i++ {
-		b[i] = 'x'
-	}
-	if n%2 == 0 {
-		b[n-1] = 'y'
-	}
-	return string(b)
-}
diff --git a/problems/generate-a-string-with-characters-that-have-odd-counts/generate_a_string_with_characters_that_have_odd_counts_test.go b/problems/generate-a-string-with-characters-that-have-odd-counts/generate_a_string_with_characters_that_have_odd_counts_test.go
deleted file mode 100644
index 3c121cfee..000000000
--- a/problems/generate-a-string-with-characters-that-have-odd-counts/generate_a_string_with_characters_that_have_odd_counts_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1374
-
-import "testing"
-
-type testType struct {
-	in   int
-	want string
-}
-
-func TestGenerateTheString(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   4,
-			want: "xxxy",
-		},
-		{
-			in:   2,
-			want: "xy",
-		},
-		{
-			in:   7,
-			want: "xxxxxxx",
-		},
-		{
-			in:   30,
-			want: "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxy",
-		},
-	}
-	for _, tt := range tests {
-		got := generateTheString(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/generate-parentheses/README.md b/problems/generate-parentheses/README.md
deleted file mode 100644
index 733a36aa0..000000000
--- a/problems/generate-parentheses/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../merge-two-sorted-lists "Merge Two Sorted Lists")
-　　　　　　　　　　　　　　　　
-[Next >](../merge-k-sorted-lists "Merge k Sorted Lists")
-
-## [22. Generate Parentheses (Medium)](https://leetcode.com/problems/generate-parentheses "括号生成")
-
-<p>Given <code>n</code> pairs of parentheses, write a function to <em>generate all combinations of well-formed parentheses</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 3
-<strong>Output:</strong> ["((()))","(()())","(())()","()(())","()()()"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 1
-<strong>Output:</strong> ["()"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 8</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Letter Combinations of a Phone Number](../letter-combinations-of-a-phone-number) (Medium)
-  1. [Valid Parentheses](../valid-parentheses) (Easy)
diff --git a/problems/generate-parentheses/generate_parentheses.go b/problems/generate-parentheses/generate_parentheses.go
deleted file mode 100644
index 7c2c8a8dd..000000000
--- a/problems/generate-parentheses/generate_parentheses.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem22
-
-func generateParenthesis(n int) []string {
-	ans := make([]string, 0)
-	next("(", 1, 0, n, &ans)
-	return ans
-}
-
-func next(s string, l, r, n int, ans *[]string) {
-	if l == n && r == n {
-		*ans = append(*ans, s)
-	}
-	if l < n {
-		next(s+"(", l+1, r, n, ans)
-	}
-	if r < l {
-		next(s+")", l, r+1, n, ans)
-	}
-}
diff --git a/problems/generate-parentheses/generate_parentheses_test.go b/problems/generate-parentheses/generate_parentheses_test.go
deleted file mode 100644
index 3f61694ee..000000000
--- a/problems/generate-parentheses/generate_parentheses_test.go
+++ /dev/null
@@ -1,94 +0,0 @@
-package problem22
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   int
-	want []string
-}
-
-func TestGenerateParenthesis(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: 3,
-			want: []string{
-				"((()))",
-				"(()())",
-				"(())()",
-				"()(())",
-				"()()()",
-			},
-		},
-		{
-			in: 2,
-			want: []string{
-				"(())",
-				"()()",
-			},
-		},
-		{
-			in:   1,
-			want: []string{"()"},
-		},
-		{
-			in:   0,
-			want: []string{},
-		},
-		{
-			in: 5,
-			want: []string{
-				"((((()))))",
-				"(((()())))",
-				"(((())()))",
-				"(((()))())",
-				"(((())))()",
-				"((()(())))",
-				"((()()()))",
-				"((()())())",
-				"((()()))()",
-				"((())(()))",
-				"((())()())",
-				"((())())()",
-				"((()))(())",
-				"((()))()()",
-				"(()((())))",
-				"(()(()()))",
-				"(()(())())",
-				"(()(()))()",
-				"(()()(()))",
-				"(()()()())",
-				"(()()())()",
-				"(()())(())",
-				"(()())()()",
-				"(())((()))",
-				"(())(()())",
-				"(())(())()",
-				"(())()(())",
-				"(())()()()",
-				"()(((())))",
-				"()((()()))",
-				"()((())())",
-				"()((()))()",
-				"()(()(()))",
-				"()(()()())",
-				"()(()())()",
-				"()(())(())",
-				"()(())()()",
-				"()()((()))",
-				"()()(()())",
-				"()()(())()",
-				"()()()(())",
-				"()()()()()",
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := generateParenthesis(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/generate-random-point-in-a-circle/README.md b/problems/generate-random-point-in-a-circle/README.md
deleted file mode 100644
index 3ba2759c5..000000000
--- a/problems/generate-random-point-in-a-circle/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../total-hamming-distance "Total Hamming Distance")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-palindrome-product "Largest Palindrome Product")
-
-## [478. Generate Random Point in a Circle (Medium)](https://leetcode.com/problems/generate-random-point-in-a-circle "在圆内随机生成点")
-
-<p>Given the radius and the position of the center of a circle, implement the function <code>randPoint</code> which generates a uniform random point inside the circle.</p>
-
-<p>Implement the <code>Solution</code> class:</p>
-
-<ul>
-	<li><code>Solution(double radius, double x_center, double y_center)</code> initializes the object with the radius of the circle <code>radius</code> and the position of the center <code>(x_center, y_center)</code>.</li>
-	<li><code>randPoint()</code> returns a random point inside the circle. A point on the circumference of the circle is considered to be in the circle. The answer is returned as an array <code>[x, y]</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Solution&quot;, &quot;randPoint&quot;, &quot;randPoint&quot;, &quot;randPoint&quot;]
-[[1.0, 0.0, 0.0], [], [], []]
-<strong>Output</strong>
-[null, [-0.02493, -0.38077], [0.82314, 0.38945], [0.36572, 0.17248]]
-
-<strong>Explanation</strong>
-Solution solution = new Solution(1.0, 0.0, 0.0);
-solution.randPoint(); // return [-0.02493, -0.38077]
-solution.randPoint(); // return [0.82314, 0.38945]
-solution.randPoint(); // return [0.36572, 0.17248]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;&nbsp;radius &lt;= 10<sup>8</sup></code></li>
-	<li><code>-10<sup>7</sup> &lt;= x_center, y_center &lt;= 10<sup>7</sup></code></li>
-	<li>At most <code>3 * 10<sup>4</sup></code> calls will be made to <code>randPoint</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Rejection Sampling](../../tag/rejection-sampling/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Similar Questions
-  1. [Random Point in Non-overlapping Rectangles](../random-point-in-non-overlapping-rectangles) (Medium)
diff --git a/problems/generate-random-point-in-a-circle/generate_random_point_in_a_circle.go b/problems/generate-random-point-in-a-circle/generate_random_point_in_a_circle.go
deleted file mode 100644
index 489500200..000000000
--- a/problems/generate-random-point-in-a-circle/generate_random_point_in_a_circle.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem478
diff --git a/problems/generate-random-point-in-a-circle/generate_random_point_in_a_circle_test.go b/problems/generate-random-point-in-a-circle/generate_random_point_in_a_circle_test.go
deleted file mode 100644
index 489500200..000000000
--- a/problems/generate-random-point-in-a-circle/generate_random_point_in_a_circle_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem478
diff --git a/problems/get-biggest-three-rhombus-sums-in-a-grid/README.md b/problems/get-biggest-three-rhombus-sums-in-a-grid/README.md
deleted file mode 100644
index 0d8c4cfcf..000000000
--- a/problems/get-biggest-three-rhombus-sums-in-a-grid/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimize-maximum-pair-sum-in-array "Minimize Maximum Pair Sum in Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-xor-sum-of-two-arrays "Minimum XOR Sum of Two Arrays")
-
-## [1878. Get Biggest Three Rhombus Sums in a Grid (Medium)](https://leetcode.com/problems/get-biggest-three-rhombus-sums-in-a-grid "矩阵中最大的三个菱形和")
-
-<p>You are given an <code>m x n</code> integer matrix <code>grid</code>​​​.</p>
-
-<p>A <strong>rhombus sum</strong> is the sum of the elements that form <strong>the</strong> <strong>border</strong> of a regular rhombus shape in <code>grid</code>​​​. The rhombus must have the shape of a square rotated 45 degrees with each of the corners centered in a grid cell. Below is an image of four valid rhombus shapes with the corresponding colored cells that should be included in each <strong>rhombus sum</strong>:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/23/pc73-q4-desc-2.png" style="width: 385px; height: 385px;" />
-<p>Note that the rhombus can have an area of 0, which is depicted by the purple rhombus in the bottom right corner.</p>
-
-<p>Return <em>the biggest three <strong>distinct rhombus sums</strong> in the </em><code>grid</code><em> in <strong>descending order</strong></em><em>. If there are less than three distinct values, return all of them</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/23/pc73-q4-ex1.png" style="width: 360px; height: 361px;" />
-<pre>
-<strong>Input:</strong> grid = [[3,4,5,1,3],[3,3,4,2,3],[20,30,200,40,10],[1,5,5,4,1],[4,3,2,2,5]]
-<strong>Output:</strong> [228,216,211]
-<strong>Explanation:</strong> The rhombus shapes for the three biggest distinct rhombus sums are depicted above.
-- Blue: 20 + 3 + 200 + 5 = 228
-- Red: 200 + 2 + 10 + 4 = 216
-- Green: 5 + 200 + 4 + 2 = 211
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/23/pc73-q4-ex2.png" style="width: 217px; height: 217px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,2,3],[4,5,6],[7,8,9]]
-<strong>Output:</strong> [20,9,8]
-<strong>Explanation:</strong> The rhombus shapes for the three biggest distinct rhombus sums are depicted above.
-- Blue: 4 + 2 + 6 + 8 = 20
-- Red: 9 (area 0 rhombus in the bottom right corner)
-- Green: 8 (area 0 rhombus in the bottom middle)
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[7,7,7]]
-<strong>Output:</strong> [7]
-<strong>Explanation:</strong> All three possible rhombus sums are the same, so return [7].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>1 &lt;= grid[i][j] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You need to maintain only the biggest 3 distinct sums
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The limits are small enough for you to iterate over all rhombus sizes then iterate over all possible borders to get the sums
-</details>
diff --git a/problems/get-equal-substrings-within-budget/README.md b/problems/get-equal-substrings-within-budget/README.md
deleted file mode 100644
index 56d17a731..000000000
--- a/problems/get-equal-substrings-within-budget/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-number-of-occurrences "Unique Number of Occurrences")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-all-adjacent-duplicates-in-string-ii "Remove All Adjacent Duplicates in String II")
-
-## [1208. Get Equal Substrings Within Budget (Medium)](https://leetcode.com/problems/get-equal-substrings-within-budget "尽可能使字符串相等")
-
-<p>You are given two strings <code>s</code> and <code>t</code> of the same length. You want to change <code>s</code> to <code>t</code>. Changing the <code>i</code>-th character of <code>s</code> to <code>i</code>-th character of <code>t</code> costs <code>|s[i] - t[i]|</code> that is, the absolute difference between the ASCII values of the characters.</p>
-
-<p>You are also given an integer <code>maxCost</code>.</p>
-
-<p>Return the maximum length of a substring of <code>s</code> that can be changed to be the same as the corresponding substring of <code>t</code>with a cost less than or equal to <code>maxCost</code>.</p>
-
-<p>If there is no substring from&nbsp;<code>s</code> that can be changed to its corresponding substring from <code>t</code>, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcd&quot;, t = &quot;bcdf&quot;, maxCost = 3
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>&quot;abc&quot; of s can change to &quot;bcd&quot;. That costs 3, so the maximum length is 3.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcd&quot;, t = &quot;cdef&quot;, maxCost = 3
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>Each character in s costs 2 to change to charactor in <code>t, so the maximum length is 1.</code>
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcd&quot;, t = &quot;acde&quot;, maxCost = 0
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>You can&#39;t make any change, so the maximum length is 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, t.length &lt;= 10^5</code></li>
-	<li><code>0 &lt;= maxCost &lt;= 10^6</code></li>
-	<li><code>s</code> and&nbsp;<code>t</code> only contain lower case English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Calculate the differences between a[i] and b[i].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a sliding window to track the longest valid substring.
-</details>
diff --git a/problems/get-highest-answer-rate-question/README.md b/problems/get-highest-answer-rate-question/README.md
deleted file mode 100644
index fe5999032..000000000
--- a/problems/get-highest-answer-rate-question/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../employee-bonus "Employee Bonus")
-　　　　　　　　　　　　　　　　
-[Next >](../find-cumulative-salary-of-an-employee "Find Cumulative Salary of an Employee")
-
-## [578. Get Highest Answer Rate Question (Medium)](https://leetcode.com/problems/get-highest-answer-rate-question "查询回答率最高的问题")
-
-<p>Get the highest answer rate question from a table <code>survey_log</code> with these columns: <b>uid</b>, <b>action</b>, <b>question_id</b>, <b>answer_id</b>, <b>q_num</b>, <b>timestamp</b>.</p>
-
-<p>uid means user id; action has these kind of values: &quot;show&quot;, &quot;answer&quot;, &quot;skip&quot;; answer_id is not null when action column is &quot;answer&quot;, while is null for &quot;show&quot; and &quot;skip&quot;; q_num is the numeral order of the question in current session.</p>
-
-<p>Write a sql query to identify the question which has the highest answer rate.</p>
-
-<p><b>Example:</b></p>
-
-<pre><b>Input:</b>
-+------+-----------+--------------+------------+-----------+------------+
-| uid  | action    | question_id  | answer_id  | q_num     | timestamp  |
-+------+-----------+--------------+------------+-----------+------------+
-| 5    | show      | 285          | null       | 1         | 123        |
-| 5    | answer    | 285          | 124124     | 1         | 124        |
-| 5    | show      | 369          | null       | 2         | 125        |
-| 5    | skip      | 369          | null       | 2         | 126        |
-+------+-----------+--------------+------------+-----------+------------+
-<b>Output:</b>
-+-------------+
-| survey_log  |
-+-------------+
-|    285      |
-+-------------+
-<b>Explanation:</b>
-question 285 has answer rate 1/1, while question 369 has 0/1 answer rate, so output 285.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b> The highest answer rate meaning is: answer number&#39;s ratio in show number in the same question.</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to find all question ids by group
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to find each group answer number and show number.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Rank all the rates (answer/(answer+show)) and return the max one
-</details>
diff --git a/problems/get-highest-answer-rate-question/get_highest_answer_rate_question.sql b/problems/get-highest-answer-rate-question/get_highest_answer_rate_question.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/get-highest-answer-rate-question/get_highest_answer_rate_question.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/get-highest-answer-rate-question/mysql_schemas.sql b/problems/get-highest-answer-rate-question/mysql_schemas.sql
deleted file mode 100644
index c0c01f73a..000000000
--- a/problems/get-highest-answer-rate-question/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists SurveyLog (id int, action varchar(255), question_id int, answer_id int, q_num int, timestamp int);
-Truncate table SurveyLog;
-insert into SurveyLog (id, action, question_id, answer_id, q_num, timestamp) values ('5', 'show', '285', 'None', '1', '123');
-insert into SurveyLog (id, action, question_id, answer_id, q_num, timestamp) values ('5', 'answer', '285', '124124', '1', '124');
-insert into SurveyLog (id, action, question_id, answer_id, q_num, timestamp) values ('5', 'show', '369', 'None', '2', '125');
-insert into SurveyLog (id, action, question_id, answer_id, q_num, timestamp) values ('5', 'skip', '369', 'None', '2', '126');
diff --git a/problems/get-maximum-in-generated-array/README.md b/problems/get-maximum-in-generated-array/README.md
deleted file mode 100644
index e5d390300..000000000
--- a/problems/get-maximum-in-generated-array/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../hopper-company-queries-ii "Hopper Company Queries II")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-deletions-to-make-character-frequencies-unique "Minimum Deletions to Make Character Frequencies Unique")
-
-## [1646. Get Maximum in Generated Array (Easy)](https://leetcode.com/problems/get-maximum-in-generated-array "获取生成数组中的最大值")
-
-<p>You are given an integer <code>n</code>. A <strong>0-indexed</strong> integer array <code>nums</code> of length <code>n + 1</code> is generated in the following way:</p>
-
-<ul>
-	<li><code>nums[0] = 0</code></li>
-	<li><code>nums[1] = 1</code></li>
-	<li><code>nums[2 * i] = nums[i]</code> when <code>2 &lt;= 2 * i &lt;= n</code></li>
-	<li><code>nums[2 * i + 1] = nums[i] + nums[i + 1]</code> when <code>2 &lt;= 2 * i + 1 &lt;= n</code></li>
-</ul>
-
-<p>Return<strong> </strong><em>the <strong>maximum</strong> integer in the array </em><code>nums</code>​​​.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> According to the given rules:
-  nums[0] = 0
-  nums[1] = 1
-  nums[(1 * 2) = 2] = nums[1] = 1
-  nums[(1 * 2) + 1 = 3] = nums[1] + nums[2] = 1 + 1 = 2
-  nums[(2 * 2) = 4] = nums[2] = 1
-  nums[(2 * 2) + 1 = 5] = nums[2] + nums[3] = 1 + 2 = 3
-  nums[(3 * 2) = 6] = nums[3] = 2
-  nums[(3 * 2) + 1 = 7] = nums[3] + nums[4] = 2 + 1 = 3
-Hence, nums = [0,1,1,2,1,3,2,3], and the maximum is max(0,1,1,2,1,3,2,3) = 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> According to the given rules, nums = [0,1,1]. The maximum is max(0,1,1) = 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> According to the given rules, nums = [0,1,1,2]. The maximum is max(0,1,1,2) = 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try generating the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Make sure not to fall in the base case of 0.
-</details>
diff --git a/problems/get-the-maximum-score/README.md b/problems/get-the-maximum-score/README.md
deleted file mode 100644
index 26e258cc6..000000000
--- a/problems/get-the-maximum-score/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-swaps-to-arrange-a-binary-grid "Minimum Swaps to Arrange a Binary Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../guess-the-majority-in-a-hidden-array "Guess the Majority in a Hidden Array")
-
-## [1537. Get the Maximum Score (Hard)](https://leetcode.com/problems/get-the-maximum-score "最大得分")
-
-<p>You are given two <strong>sorted</strong> arrays of distinct integers <code>nums1</code> and <code>nums2.</code></p>
-
-<p>A <strong>valid<strong><em> </em></strong>path</strong> is defined as follows:</p>
-
-<ul>
-	<li>Choose array <code>nums1</code> or <code>nums2</code> to traverse (from index-0).</li>
-	<li>Traverse the current array from left to right.</li>
-	<li>If you are reading any value that is present in <code>nums1</code> and <code>nums2</code> you are allowed to change your path to the other array. (Only one repeated value is considered in the valid path).</li>
-</ul>
-
-<p>The <strong>score</strong> is defined as the sum of uniques values in a valid path.</p>
-
-<p>Return <em>the maximum score you can obtain of all possible <strong>valid paths</strong></em>. Since the answer may be too large, return it modulo <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/16/sample_1_1893.png" style="width: 500px; height: 151px;" />
-<pre>
-<strong>Input:</strong> nums1 = [2,4,5,8,10], nums2 = [4,6,8,9]
-<strong>Output:</strong> 30
-<strong>Explanation:</strong> Valid paths:
-[2,4,5,8,10], [2,4,5,8,9], [2,4,6,8,9], [2,4,6,8,10],  (starting from nums1)
-[4,6,8,9], [4,5,8,10], [4,5,8,9], [4,6,8,10]    (starting from nums2)
-The maximum is obtained with the path in green <strong>[2,4,6,8,10]</strong>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,3,5,7,9], nums2 = [3,5,100]
-<strong>Output:</strong> 109
-<strong>Explanation:</strong> Maximum sum is obtained with the path <strong>[1,3,5,100]</strong>.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2,3,4,5], nums2 = [6,7,8,9,10]
-<strong>Output:</strong> 40
-<strong>Explanation:</strong> There are no common elements between nums1 and nums2.
-Maximum sum is obtained with the path [6,7,8,9,10].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums1[i], nums2[i] &lt;= 10<sup>7</sup></code></li>
-	<li><code>nums1</code> and <code>nums2</code> are strictly increasing.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Partition the array by common integers, and choose the path with larger sum with a DP technique.
-</details>
diff --git a/problems/get-the-second-most-recent-activity/README.md b/problems/get-the-second-most-recent-activity/README.md
deleted file mode 100644
index 60c83d6b0..000000000
--- a/problems/get-the-second-most-recent-activity/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-make-at-least-one-valid-path-in-a-grid "Minimum Cost to Make at Least One Valid Path in a Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../increasing-decreasing-string "Increasing Decreasing String")
-
-## [1369. Get the Second Most Recent Activity (Hard)](https://leetcode.com/problems/get-the-second-most-recent-activity "获取最近第二次的活动")
-
-SQL Schema
-<p>Table: <code>UserActivity</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| username      | varchar |
-| activity      | varchar |
-| startDate     | Date    |
-| endDate       | Date    |
-+---------------+---------+
-This table does not contain primary key.
-This table contain information about the activity performed of each user in a period of time.
-A person with username performed a activity from startDate to endDate.
-</pre>
-
-Write an SQL query to show the second most recent activity of each user.
-
-If the user only has one activity, return that one. 
-
-A user can't perform more than one activity at the same time. Return the result table in any order.
-
-The query result format is in the following example:
-<pre>
-UserActivity table:
-+------------+--------------+-------------+-------------+
-| username   | activity     | startDate   | endDate     |
-+------------+--------------+-------------+-------------+
-| Alice      | Travel       | 2020-02-12  | 2020-02-20  |
-| Alice      | Dancing      | 2020-02-21  | 2020-02-23  |
-| Alice      | Travel       | 2020-02-24  | 2020-02-28  |
-| Bob        | Travel       | 2020-02-11  | 2020-02-18  |
-+------------+--------------+-------------+-------------+
-
-Result table:
-+------------+--------------+-------------+-------------+
-| username   | activity     | startDate   | endDate     |
-+------------+--------------+-------------+-------------+
-| Alice      | Dancing      | 2020-02-21  | 2020-02-23  |
-| Bob        | Travel       | 2020-02-11  | 2020-02-18  |
-+------------+--------------+-------------+-------------+
-
-The most recent activity of Alice is Travel from 2020-02-24 to 2020-02-28, before that she was dancing from 2020-02-21 to 2020-02-23.
-Bob only has one record, we just take that one.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/get-the-second-most-recent-activity/mysql_schemas.sql b/problems/get-the-second-most-recent-activity/mysql_schemas.sql
deleted file mode 100644
index 880eded3e..000000000
--- a/problems/get-the-second-most-recent-activity/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists UserActivity (username varchar(30), activity varchar(30), startDate date, endDate date);
-Truncate table UserActivity;
-insert into UserActivity (username, activity, startDate, endDate) values ('Alice', 'Travel', '2020-02-12', '2020-02-20');
-insert into UserActivity (username, activity, startDate, endDate) values ('Alice', 'Dancing', '2020-02-21', '2020-02-23');
-insert into UserActivity (username, activity, startDate, endDate) values ('Alice', 'Travel', '2020-02-24', '2020-02-28');
-insert into UserActivity (username, activity, startDate, endDate) values ('Bob', 'Travel', '2020-02-11', '2020-02-18');
diff --git a/problems/get-watched-videos-by-your-friends/README.md b/problems/get-watched-videos-by-your-friends/README.md
deleted file mode 100644
index 79c0f3213..000000000
--- a/problems/get-watched-videos-by-your-friends/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../xor-queries-of-a-subarray "XOR Queries of a Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-insertion-steps-to-make-a-string-palindrome "Minimum Insertion Steps to Make a String Palindrome")
-
-## [1311. Get Watched Videos by Your Friends (Medium)](https://leetcode.com/problems/get-watched-videos-by-your-friends "获取你好友已观看的视频")
-
-<p>There are <code>n</code> people, each person has a unique <em>id</em> between <code>0</code> and <code>n-1</code>. Given the arrays <code>watchedVideos</code> and <code>friends</code>, where <code>watchedVideos[i]</code> and <code>friends[i]</code> contain the list of watched videos and the list of friends respectively for the person with <code>id = i</code>.</p>
-
-<p>Level <strong>1</strong> of videos are all watched videos by your&nbsp;friends, level <strong>2</strong> of videos are all watched videos by the friends of your&nbsp;friends and so on. In general, the level <code>k</code> of videos are all&nbsp;watched videos by people&nbsp;with the shortest path <strong>exactly</strong> equal&nbsp;to&nbsp;<code>k</code> with you. Given your&nbsp;<code>id</code> and the <code>level</code> of videos, return the list of videos ordered by their frequencies (increasing). For videos with the same frequency order them alphabetically from least to greatest.&nbsp;</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/01/02/leetcode_friends_1.png" style="width: 144px; height: 200px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> watchedVideos = [[&quot;A&quot;,&quot;B&quot;],[&quot;C&quot;],[&quot;B&quot;,&quot;C&quot;],[&quot;D&quot;]], friends = [[1,2],[0,3],[0,3],[1,2]], id = 0, level = 1
-<strong>Output:</strong> [&quot;B&quot;,&quot;C&quot;] 
-<strong>Explanation:</strong> 
-You have id = 0 (green color in the figure) and your friends are (yellow color in the figure):
-Person with id = 1 -&gt; watchedVideos = [&quot;C&quot;]&nbsp;
-Person with id = 2 -&gt; watchedVideos = [&quot;B&quot;,&quot;C&quot;]&nbsp;
-The frequencies of watchedVideos by your friends are:&nbsp;
-B -&gt; 1&nbsp;
-C -&gt; 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/01/02/leetcode_friends_2.png" style="width: 144px; height: 200px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> watchedVideos = [[&quot;A&quot;,&quot;B&quot;],[&quot;C&quot;],[&quot;B&quot;,&quot;C&quot;],[&quot;D&quot;]], friends = [[1,2],[0,3],[0,3],[1,2]], id = 0, level = 2
-<strong>Output:</strong> [&quot;D&quot;]
-<strong>Explanation:</strong> 
-You have id = 0 (green color in the figure) and the only friend of your friends is the person with id = 3 (yellow color in the figure).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == watchedVideos.length ==&nbsp;friends.length</code></li>
-	<li><code>2 &lt;= n&nbsp;&lt;= 100</code></li>
-	<li><code>1 &lt;=&nbsp;watchedVideos[i].length &lt;= 100</code></li>
-	<li><code>1 &lt;=&nbsp;watchedVideos[i][j].length &lt;= 8</code></li>
-	<li><code>0 &lt;= friends[i].length &lt; n</code></li>
-	<li><code>0 &lt;= friends[i][j]&nbsp;&lt; n</code></li>
-	<li><code>0 &lt;= id &lt; n</code></li>
-	<li><code>1 &lt;= level &lt; n</code></li>
-	<li>if&nbsp;<code>friends[i]</code> contains <code>j</code>, then <code>friends[j]</code> contains <code>i</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do BFS to find the kth level friends.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Then collect movies saw by kth level friends and sort them accordingly.
-</details>
diff --git a/problems/global-and-local-inversions/README.md b/problems/global-and-local-inversions/README.md
deleted file mode 100644
index 37e03dcb7..000000000
--- a/problems/global-and-local-inversions/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimize-max-distance-to-gas-station "Minimize Max Distance to Gas Station")
-　　　　　　　　　　　　　　　　
-[Next >](../split-bst "Split BST")
-
-## [775. Global and Local Inversions (Medium)](https://leetcode.com/problems/global-and-local-inversions "全局倒置与局部倒置")
-
-<p>You are given an integer array <code>nums</code> of length <code>n</code> which represents a permutation of all the integers in the range <code>[0, n - 1]</code>.</p>
-
-<p>The number of <strong>global inversions</strong> is the number of the different pairs <code>(i, j)</code> where:</p>
-
-<ul>
-	<li><code>0 &lt;= i &lt; j &lt; n</code></li>
-	<li><code>nums[i] &gt; nums[j]</code></li>
-</ul>
-
-<p>The number of <strong>local inversions</strong> is the number of indices <code>i</code> where:</p>
-
-<ul>
-	<li><code>0 &lt;= i &lt; n - 1</code></li>
-	<li><code>nums[i] &gt; nums[i + 1]</code></li>
-</ul>
-
-<p>Return <code>true</code> <em>if the number of <strong>global inversions</strong> is equal to the number of <strong>local inversions</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,0,2]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> There is 1 global inversion and 1 local inversion.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,0]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There are 2 global inversions and 1 local inversion.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt; n</code></li>
-	<li>All the integers of <code>nums</code> are <strong>unique</strong>.</li>
-	<li><code>nums</code> is a permutation of all the numbers in the range <code>[0, n - 1]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Where can the 0 be placed in an ideal permutation?  What about the 1?
-</details>
diff --git a/problems/global-and-local-inversions/global_and_local_inversions.go b/problems/global-and-local-inversions/global_and_local_inversions.go
deleted file mode 100644
index 82fa03e35..000000000
--- a/problems/global-and-local-inversions/global_and_local_inversions.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem775
diff --git a/problems/global-and-local-inversions/global_and_local_inversions_test.go b/problems/global-and-local-inversions/global_and_local_inversions_test.go
deleted file mode 100644
index 82fa03e35..000000000
--- a/problems/global-and-local-inversions/global_and_local_inversions_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem775
diff --git a/problems/goal-parser-interpretation/README.md b/problems/goal-parser-interpretation/README.md
deleted file mode 100644
index bb3dee44a..000000000
--- a/problems/goal-parser-interpretation/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../products-worth-over-invoices "Product's Worth Over Invoices")
-　　　　　　　　　　　　　　　　
-[Next >](../max-number-of-k-sum-pairs "Max Number of K-Sum Pairs")
-
-## [1678. Goal Parser Interpretation (Easy)](https://leetcode.com/problems/goal-parser-interpretation "设计 Goal 解析器")
-
-<p>You own a <strong>Goal Parser</strong> that can interpret a string <code>command</code>. The <code>command</code> consists of an alphabet of <code>&quot;G&quot;</code>, <code>&quot;()&quot;</code> and/or <code>&quot;(al)&quot;</code> in some order. The Goal Parser will interpret <code>&quot;G&quot;</code> as the string <code>&quot;G&quot;</code>, <code>&quot;()&quot;</code> as the string <code>&quot;o&quot;</code>, and <code>&quot;(al)&quot;</code> as the string <code>&quot;al&quot;</code>. The interpreted strings are then concatenated in the original order.</p>
-
-<p>Given the string <code>command</code>, return <em>the <strong>Goal Parser</strong>&#39;s interpretation of </em><code>command</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> command = &quot;G()(al)&quot;
-<strong>Output:</strong> &quot;Goal&quot;
-<strong>Explanation:</strong>&nbsp;The Goal Parser interprets the command as follows:
-G -&gt; G
-() -&gt; o
-(al) -&gt; al
-The final concatenated result is &quot;Goal&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> command = &quot;G()()()()(al)&quot;
-<strong>Output:</strong> &quot;Gooooal&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> command = &quot;(al)G(al)()()G&quot;
-<strong>Output:</strong> &quot;alGalooG&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= command.length &lt;= 100</code></li>
-	<li><code>command</code> consists of <code>&quot;G&quot;</code>, <code>&quot;()&quot;</code>, and/or <code>&quot;(al)&quot;</code> in some order.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You need to check at most 2 characters to determine which character comes next.
-</details>
diff --git a/problems/goat-latin/README.md b/problems/goat-latin/README.md
deleted file mode 100644
index 113402d0a..000000000
--- a/problems/goat-latin/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-trees-with-factors "Binary Trees With Factors")
-　　　　　　　　　　　　　　　　
-[Next >](../friends-of-appropriate-ages "Friends Of Appropriate Ages")
-
-## [824. Goat Latin (Easy)](https://leetcode.com/problems/goat-latin "山羊拉丁文")
-
-<p>You are given a string <code>sentence</code> that consist of words separated by spaces. Each word consists of lowercase and uppercase letters only.</p>
-
-<p>We would like to convert the sentence to &quot;Goat Latin&quot; (a made-up language similar to Pig Latin.) The rules of Goat Latin are as follows:</p>
-
-<ul>
-	<li>If a word begins with a vowel (<code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, or <code>&#39;u&#39;</code>), append <code>&quot;ma&quot;</code> to the end of the word.
-	<ul>
-		<li>For example, the word <code>&quot;apple&quot;</code> becomes <code>&quot;applema&quot;</code>.</li>
-	</ul>
-	</li>
-	<li>If a word begins with a consonant (i.e., not a vowel), remove the first letter and append it to the end, then add <code>&quot;ma&quot;</code>.
-	<ul>
-		<li>For example, the word <code>&quot;goat&quot;</code> becomes <code>&quot;oatgma&quot;</code>.</li>
-	</ul>
-	</li>
-	<li>Add one letter <code>&#39;a&#39;</code> to the end of each word per its word index in the sentence, starting with <code>1</code>.
-	<ul>
-		<li>For example, the first word gets <code>&quot;a&quot;</code> added to the end, the second word gets <code>&quot;aa&quot;</code> added to the end, and so on.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return<em> the final sentence representing the conversion from sentence to Goat Latin</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> sentence = "I speak Goat Latin"
-<strong>Output:</strong> "Imaa peaksmaaa oatGmaaaa atinLmaaaaa"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> sentence = "The quick brown fox jumped over the lazy dog"
-<strong>Output:</strong> "heTmaa uickqmaaa rownbmaaaa oxfmaaaaa umpedjmaaaaaa overmaaaaaaa hetmaaaaaaaa azylmaaaaaaaaa ogdmaaaaaaaaaa"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= sentence.length &lt;= 150</code></li>
-	<li><code>sentence</code> consists of English letters and spaces.</li>
-	<li><code>sentence</code> has no leading or trailing spaces.</li>
-	<li>All the words in <code>sentence</code> are separated by a single space.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/goat-latin/goat_latin.go b/problems/goat-latin/goat_latin.go
deleted file mode 100644
index 58fd43629..000000000
--- a/problems/goat-latin/goat_latin.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem824
-
-import "strings"
-
-func toGoatLatin(S string) string {
-	ans := ""
-	s := strings.Split(S, " ")
-	for i, word := range s {
-		switch word[0] {
-		case 'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U':
-			ans += " " + word + "ma"
-		default:
-			ans += " " + word[1:] + word[0:1] + "ma"
-		}
-		ans += strings.Repeat("a", i+1)
-	}
-	return ans[1:]
-}
diff --git a/problems/goat-latin/goat_latin_test.go b/problems/goat-latin/goat_latin_test.go
deleted file mode 100644
index 2f0d8b971..000000000
--- a/problems/goat-latin/goat_latin_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem824
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestToGoatLatin(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "I speak Goat Latin",
-			want: "Imaa peaksmaaa oatGmaaaa atinLmaaaaa",
-		},
-		{
-			in:   "The quick brown fox jumped over the lazy dog",
-			want: "heTmaa uickqmaaa rownbmaaaa oxfmaaaaa umpedjmaaaaaa overmaaaaaaa hetmaaaaaaaa azylmaaaaaaaaa ogdmaaaaaaaaaa",
-		},
-	}
-	for _, tt := range tests {
-		got := toGoatLatin(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/grand-slam-titles/README.md b/problems/grand-slam-titles/README.md
deleted file mode 100644
index f47024e06..000000000
--- a/problems/grand-slam-titles/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-pairs-of-nodes "Count Pairs Of Nodes")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-binary-string-has-at-most-one-segment-of-ones "Check if Binary String Has at Most One Segment of Ones")
-
-## [1783. Grand Slam Titles (Medium)](https://leetcode.com/problems/grand-slam-titles "大满贯数量")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/grand-slam-titles/mysql_schemas.sql b/problems/grand-slam-titles/mysql_schemas.sql
deleted file mode 100644
index dd19af729..000000000
--- a/problems/grand-slam-titles/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Players (player_id int, player_name varchar(20));
-Create table If Not Exists Championships (year int, Wimbledon int, Fr_open int, US_open int, Au_open int);
-Truncate table Players;
-insert into Players (player_id, player_name) values ('1', 'Nadal');
-insert into Players (player_id, player_name) values ('2', 'Federer');
-insert into Players (player_id, player_name) values ('3', 'Novak');
-Truncate table Championships;
-insert into Championships (year, Wimbledon, Fr_open, US_open, Au_open) values ('2018', '1', '1', '1', '1');
-insert into Championships (year, Wimbledon, Fr_open, US_open, Au_open) values ('2019', '1', '1', '2', '2');
-insert into Championships (year, Wimbledon, Fr_open, US_open, Au_open) values ('2020', '2', '1', '2', '2');
diff --git a/problems/graph-connectivity-with-threshold/README.md b/problems/graph-connectivity-with-threshold/README.md
deleted file mode 100644
index c09292090..000000000
--- a/problems/graph-connectivity-with-threshold/README.md
+++ /dev/null
@@ -1,95 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-team-with-no-conflicts "Best Team With No Conflicts")
-　　　　　　　　　　　　　　　　
-[Next >](../design-an-expression-tree-with-evaluate-function "Design an Expression Tree With Evaluate Function")
-
-## [1627. Graph Connectivity With Threshold (Hard)](https://leetcode.com/problems/graph-connectivity-with-threshold "带阈值的图连通性")
-
-<p>We have <code>n</code> cities labeled from <code>1</code> to <code>n</code>. Two different cities with labels <code>x</code> and <code>y</code> are directly connected by a bidirectional road if and only if <code>x</code> and <code>y</code> share a common divisor <strong>strictly greater</strong> than some <code>threshold</code>. More formally, cities with labels <code>x</code> and <code>y</code> have a road between them if there exists an integer <code>z</code> such that all of the following are true:</p>
-
-<ul>
-	<li><code>x % z == 0</code>,</li>
-	<li><code>y % z == 0</code>, and</li>
-	<li><code>z &gt; threshold</code>.</li>
-</ul>
-
-<p>Given the two integers, <code>n</code> and <code>threshold</code>, and an array of <code>queries</code>, you must determine for each <code>queries[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> if cities <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code> are connected directly or indirectly.&nbsp;(i.e. there is some path between them).</p>
-
-<p>Return <em>an array </em><code>answer</code><em>, where </em><code>answer.length == queries.length</code><em> and </em><code>answer[i]</code><em> is </em><code>true</code><em> if for the </em><code>i<sup>th</sup></code><em> query, there is a path between </em><code>a<sub>i</sub></code><em> and </em><code>b<sub>i</sub></code><em>, or </em><code>answer[i]</code><em> is </em><code>false</code><em> if there is no path.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/09/ex1.jpg" style="width: 382px; height: 181px;" />
-<pre>
-<strong>Input:</strong> n = 6, threshold = 2, queries = [[1,4],[2,5],[3,6]]
-<strong>Output:</strong> [false,false,true]
-<strong>Explanation:</strong> The divisors for each number:
-1:   1
-2:   1, 2
-3:   1, <u>3</u>
-4:   1, 2, <u>4</u>
-5:   1, <u>5</u>
-6:   1, 2, <u>3</u>, <u>6</u>
-Using the underlined divisors above the threshold, only cities 3 and 6 share a common divisor, so they are the
-only ones directly connected. The result of each query:
-[1,4]   1 is not connected to 4
-[2,5]   2 is not connected to 5
-[3,6]   3 is connected to 6 through path 3--6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/10/tmp.jpg" style="width: 532px; height: 302px;" />
-<pre>
-<strong>Input:</strong> n = 6, threshold = 0, queries = [[4,5],[3,4],[3,2],[2,6],[1,3]]
-<strong>Output:</strong> [true,true,true,true,true]
-<strong>Explanation:</strong> The divisors for each number are the same as the previous example. However, since the threshold is 0,
-all divisors can be used. Since all numbers share 1 as a divisor, all cities are connected.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/17/ex3.jpg" style="width: 282px; height: 282px;" />
-<pre>
-<strong>Input:</strong> n = 5, threshold = 1, queries = [[4,5],[4,5],[3,2],[2,3],[3,4]]
-<strong>Output:</strong> [false,false,false,false,false]
-<strong>Explanation:</strong> Only cities 2 and 4 share a common divisor 2 which is strictly greater than the threshold 1, so they are the only ones directly connected.
-Please notice that there can be multiple queries for the same pair of nodes [x, y], and that the query [x, y] is equivalent to the query [y, x].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= threshold &lt;= n</code></li>
-	<li><code>1 &lt;= queries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>queries[i].length == 2</code></li>
-	<li><code>1 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt;= cities</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to build the graph of the cities?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Connect city i with all its multiples 2*i, 3*i, ...
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Answer the queries using union-find data structure.
-</details>
diff --git a/problems/graph-valid-tree/README.md b/problems/graph-valid-tree/README.md
deleted file mode 100644
index ffb6f3b79..000000000
--- a/problems/graph-valid-tree/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../single-number-iii "Single Number III")
-　　　　　　　　　　　　　　　　
-[Next >](../trips-and-users "Trips and Users")
-
-## [261. Graph Valid Tree (Medium)](https://leetcode.com/problems/graph-valid-tree "以图判树")
-
-<p>Given <code>n</code> nodes labeled from <code>0</code> to <code>n-1</code> and a list of undirected edges (each edge is a pair of nodes), write a function to check whether these edges make up a valid tree.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> <code>n = 5</code>, and <code>edges = [[0,1], [0,2], [0,3], [1,4]]</code>
-<strong>Output:</strong> true</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> <code>n = 5, </code>and <code>edges = [[0,1], [1,2], [2,3], [1,3], [1,4]]</code>
-<strong>Output:</strong> false</pre>
-
-<p><b>Note</b>: you can assume that no duplicate edges will appear in <code>edges</code>. Since all edges are undirected, <code>[0,1]</code> is the same as <code>[1,0]</code> and thus will not appear together in <code>edges</code>.</p>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [Course Schedule](../course-schedule) (Medium)
-  1. [Number of Connected Components in an Undirected Graph](../number-of-connected-components-in-an-undirected-graph) (Medium)
-  1. [Keys and Rooms](../keys-and-rooms) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given <code>n = 5</code> and <code>edges = [[0, 1], [1, 2], [3, 4]]</code>, what should your return? Is this case a valid tree?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-According to the <a href="https://en.wikipedia.org/wiki/Tree_(graph_theory)" target="_blank">definition of tree on Wikipedia</a>: “a tree is an undirected graph in which any two vertices are connected by <i>exactly</i> one path. In other words, any connected graph without simple cycles is a tree.”
-</details>
diff --git a/problems/graph-valid-tree/graph_valid_tree.go b/problems/graph-valid-tree/graph_valid_tree.go
deleted file mode 100644
index 21559ad2f..000000000
--- a/problems/graph-valid-tree/graph_valid_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem261
diff --git a/problems/graph-valid-tree/graph_valid_tree_test.go b/problems/graph-valid-tree/graph_valid_tree_test.go
deleted file mode 100644
index 21559ad2f..000000000
--- a/problems/graph-valid-tree/graph_valid_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem261
diff --git a/problems/gray-code/README.md b/problems/gray-code/README.md
deleted file mode 100644
index 31ab2c962..000000000
--- a/problems/gray-code/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../merge-sorted-array "Merge Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../subsets-ii "Subsets II")
-
-## [89. Gray Code (Medium)](https://leetcode.com/problems/gray-code "格雷编码")
-
-<p>An <strong>n-bit gray code sequence</strong> is a sequence of <code>2<sup>n</sup></code> integers where:</p>
-
-<ul>
-	<li>Every integer is in the <strong>inclusive</strong> range <code>[0, 2<sup>n</sup> - 1]</code>,</li>
-	<li>The first integer is <code>0</code>,</li>
-	<li>An integer appears <strong>no more than once</strong> in the sequence,</li>
-	<li>The binary representation of every pair of <strong>adjacent</strong> integers differs by <strong>exactly one bit</strong>, and</li>
-	<li>The binary representation of the <strong>first</strong> and <strong>last</strong> integers differs by <strong>exactly one bit</strong>.</li>
-</ul>
-
-<p>Given an integer <code>n</code>, return <em>any valid <strong>n-bit gray code sequence</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> [0,1,3,2]
-<strong>Explanation:</strong>
-The binary representation of [0,1,3,2] is [00,01,11,10].
-- 0<u>0</u> and 0<u>1</u> differ by one bit
-- <u>0</u>1 and <u>1</u>1 differ by one bit
-- 1<u>1</u> and 1<u>0</u> differ by one bit
-- <u>1</u>0 and <u>0</u>0 differ by one bit
-[0,2,3,1] is also a valid gray code sequence, whose binary representation is [00,10,11,01].
-- <u>0</u>0 and <u>1</u>0 differ by one bit
-- 1<u>0</u> and 1<u>1</u> differ by one bit
-- <u>1</u>1 and <u>0</u>1 differ by one bit
-- 0<u>1</u> and 0<u>0</u> differ by one bit
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> [0,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 16</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [1-bit and 2-bit Characters](../1-bit-and-2-bit-characters) (Easy)
diff --git a/problems/gray-code/gray_code.go b/problems/gray-code/gray_code.go
deleted file mode 100644
index 4eb823717..000000000
--- a/problems/gray-code/gray_code.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem89
diff --git a/problems/gray-code/gray_code_test.go b/problems/gray-code/gray_code_test.go
deleted file mode 100644
index 4eb823717..000000000
--- a/problems/gray-code/gray_code_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem89
diff --git a/problems/greatest-common-divisor-of-strings/README.md b/problems/greatest-common-divisor-of-strings/README.md
deleted file mode 100644
index fdacf33b8..000000000
--- a/problems/greatest-common-divisor-of-strings/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../product-sales-analysis-iii "Product Sales Analysis III")
-　　　　　　　　　　　　　　　　
-[Next >](../flip-columns-for-maximum-number-of-equal-rows "Flip Columns For Maximum Number of Equal Rows")
-
-## [1071. Greatest Common Divisor of Strings (Easy)](https://leetcode.com/problems/greatest-common-divisor-of-strings "字符串的最大公因子")
-
-<p>For two strings <code>s</code> and <code>t</code>, we say &quot;<code>t</code> divides <code>s</code>&quot; if and only if <code>s = t + ... + t</code>&nbsp; (<code>t</code> concatenated with itself 1 or more times)</p>
-
-<p>Given two strings str1 and str2, return the largest string <code>x</code> such that <code>x</code> divides both&nbsp;<code><font face="monospace">str1</font></code>&nbsp;and <code><font face="monospace">str2</font></code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> str1 = "ABCABC", str2 = "ABC"
-<strong>Output:</strong> "ABC"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> str1 = "ABABAB", str2 = "ABAB"
-<strong>Output:</strong> "AB"
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> str1 = "LEET", str2 = "CODE"
-<strong>Output:</strong> ""
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> str1 = "ABCDEF", str2 = "ABC"
-<strong>Output:</strong> ""
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= str1.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= str2.length &lt;= 1000</code></li>
-	<li><code>str1</code>&nbsp;and <code>str2</code>&nbsp;consist of&nbsp;English uppercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Find Greatest Common Divisor of Array](../find-greatest-common-divisor-of-array) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The greatest common divisor must be a prefix of each string, so we can try all prefixes.
-</details>
diff --git a/problems/greatest-common-divisor-of-strings/greatest_common_divisor_of_strings.go b/problems/greatest-common-divisor-of-strings/greatest_common_divisor_of_strings.go
deleted file mode 100644
index f22da6cbd..000000000
--- a/problems/greatest-common-divisor-of-strings/greatest_common_divisor_of_strings.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem1071
-
-func gcdOfStrings(str1 string, str2 string) string {
-	if str1+str2 != str2+str1 {
-		return ""
-	}
-	return str1[:gcd(len(str1), len(str2))]
-}
-
-// 最大公约数（Greatest Common Divisor）缩写为GCD
-// 辗转相除法
-func gcd(a, b int) int {
-	if b == 0 {
-		return a
-	}
-	return gcd(b, a%b)
-}
diff --git a/problems/greatest-common-divisor-of-strings/greatest_common_divisor_of_strings_test.go b/problems/greatest-common-divisor-of-strings/greatest_common_divisor_of_strings_test.go
deleted file mode 100644
index 75fe7869c..000000000
--- a/problems/greatest-common-divisor-of-strings/greatest_common_divisor_of_strings_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1071
-
-import "testing"
-
-type testType struct {
-	str1 string
-	str2 string
-	want string
-}
-
-func TestGcdOfStrings(t *testing.T) {
-	tests := [...]testType{
-		{
-			str1: "ABCABC",
-			str2: "ABC",
-			want: "ABC",
-		},
-		{
-			str1: "ABABAB",
-			str2: "ABAB",
-			want: "AB",
-		},
-		{
-			str1: "LEET",
-			str2: "CODE",
-			want: "",
-		},
-	}
-	for _, tt := range tests {
-		got := gcdOfStrings(tt.str1, tt.str2)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.str1, got, tt.want)
-		}
-	}
-}
diff --git a/problems/greatest-sum-divisible-by-three/README.md b/problems/greatest-sum-divisible-by-three/README.md
deleted file mode 100644
index 5e1039e36..000000000
--- a/problems/greatest-sum-divisible-by-three/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-elements-in-a-contaminated-binary-tree "Find Elements in a Contaminated Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-moves-to-move-a-box-to-their-target-location "Minimum Moves to Move a Box to Their Target Location")
-
-## [1262. Greatest Sum Divisible by Three (Medium)](https://leetcode.com/problems/greatest-sum-divisible-by-three "可被三整除的最大和")
-
-<p>Given an array&nbsp;<code>nums</code>&nbsp;of integers, we need to find the maximum possible sum of elements of the array such that it is divisible by three.</p>
-
-<ol>
-</ol>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,6,5,1,8]
-<strong>Output:</strong> 18
-<strong>Explanation:</strong> Pick numbers 3, 6, 1 and 8 their sum is 18 (maximum sum divisible by 3).</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Since 4 is not divisible by 3, do not pick any number.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,4]
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> Pick numbers 1, 3, 4 and 4 their sum is 12 (maximum sum divisible by 3).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 4 * 10^4</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10^4</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Represent the state as DP[pos][mod]: maximum possible sum starting in the position "pos" in the array where the current sum modulo 3 is equal to mod.
-</details>
diff --git a/problems/grid-game/README.md b/problems/grid-game/README.md
deleted file mode 100644
index a18819ded..000000000
--- a/problems/grid-game/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-difference-between-increasing-elements "Maximum Difference Between Increasing Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-word-can-be-placed-in-crossword "Check if Word Can Be Placed In Crossword")
-
-## [2017. Grid Game (Medium)](https://leetcode.com/problems/grid-game "网格游戏")
-
-<p>You are given a <strong>0-indexed</strong> 2D array <code>grid</code> of size <code>2 x n</code>, where <code>grid[r][c]</code> represents the number of points at position <code>(r, c)</code> on the matrix. Two robots are playing a game on this matrix.</p>
-
-<p>Both robots initially start at <code>(0, 0)</code> and want to reach <code>(1, n-1)</code>. Each robot may only move to the <strong>right</strong> (<code>(r, c)</code> to <code>(r, c + 1)</code>) or <strong>down </strong>(<code>(r, c)</code> to <code>(r + 1, c)</code>).</p>
-
-<p>At the start of the game, the <strong>first</strong> robot moves from <code>(0, 0)</code> to <code>(1, n-1)</code>, collecting all the points from the cells on its path. For all cells <code>(r, c)</code> traversed on the path, <code>grid[r][c]</code> is set to <code>0</code>. Then, the <strong>second</strong> robot moves from <code>(0, 0)</code> to <code>(1, n-1)</code>, collecting the points on its path. Note that their paths may intersect with one another.</p>
-
-<p>The <strong>first</strong> robot wants to <strong>minimize</strong> the number of points collected by the <strong>second</strong> robot. In contrast, the <strong>second </strong>robot wants to <strong>maximize</strong> the number of points it collects. If both robots play <strong>optimally</strong>, return <em>the <b>number of points</b> collected by the <strong>second</strong> robot.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/08/a1.png" style="width: 388px; height: 103px;" />
-<pre>
-<strong>Input:</strong> grid = [[2,5,4],[1,5,1]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The optimal path taken by the first robot is shown in red, and the optimal path taken by the second robot is shown in blue.
-The cells visited by the first robot are set to 0.
-The second robot will collect 0 + 0 + 4 + 0 = 4 points.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/08/a2.png" style="width: 384px; height: 105px;" />
-<pre>
-<strong>Input:</strong> grid = [[3,3,1],[8,5,2]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The optimal path taken by the first robot is shown in red, and the optimal path taken by the second robot is shown in blue.
-The cells visited by the first robot are set to 0.
-The second robot will collect 0 + 3 + 1 + 0 = 4 points.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/08/a3.png" style="width: 493px; height: 103px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,3,1,15],[1,3,3,1]]
-<strong>Output:</strong> 7
-<strong>Explanation: </strong>The optimal path taken by the first robot is shown in red, and the optimal path taken by the second robot is shown in blue.
-The cells visited by the first robot are set to 0.
-The second robot will collect 0 + 1 + 3 + 3 + 0 = 7 points.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>grid.length == 2</code></li>
-	<li><code>n == grid[r].length</code></li>
-	<li><code>1 &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= grid[r][c] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There are n choices for when the first robot moves to the second row.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use prefix sums to help solve this problem?
-</details>
diff --git a/problems/grid-illumination/README.md b/problems/grid-illumination/README.md
deleted file mode 100644
index d0d90ef95..000000000
--- a/problems/grid-illumination/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-merge-stones "Minimum Cost to Merge Stones")
-　　　　　　　　　　　　　　　　
-[Next >](../find-common-characters "Find Common Characters")
-
-## [1001. Grid Illumination (Hard)](https://leetcode.com/problems/grid-illumination "网格照明")
-
-<p>There is a 2D <code>grid</code> of size <code>n x n</code> where each cell of this grid has a lamp that is initially <strong>turned off</strong>.</p>
-
-<p>You are given a 2D array of lamp positions <code>lamps</code>, where <code>lamps[i] = [row<sub>i</sub>, col<sub>i</sub>]</code> indicates that the lamp at <code>grid[row<sub>i</sub>][col<sub>i</sub>]</code> is <strong>turned on</strong>. Even if the same lamp is listed more than once, it is turned on.</p>
-
-<p>When a lamp is turned on, it <strong>illuminates its cell</strong> and <strong>all other cells</strong> in the same <strong>row, column, or diagonal</strong>.</p>
-
-<p>You are also given another 2D array <code>queries</code>, where <code>queries[j] = [row<sub>j</sub>, col<sub>j</sub>]</code>. For the <code>j<sup>th</sup></code> query, determine whether <code>grid[row<sub>j</sub>][col<sub>j</sub>]</code> is illuminated or not. After answering the <code>j<sup>th</sup></code> query, <strong>turn off</strong> the lamp at <code>grid[row<sub>j</sub>][col<sub>j</sub>]</code> and its <strong>8 adjacent lamps</strong> if they exist. A lamp is adjacent if its cell shares either a side or corner with <code>grid[row<sub>j</sub>][col<sub>j</sub>]</code>.</p>
-
-<p>Return <em>an array of integers </em><code>ans</code><em>,</em><em> where </em><code>ans[j]</code><em> should be </em><code>1</code><em> if the cell in the </em><code>j<sup>th</sup></code><em> query was illuminated, or </em><code>0</code><em> if the lamp was not.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/19/illu_1.jpg" style="width: 750px; height: 209px;" />
-<pre>
-<strong>Input:</strong> n = 5, lamps = [[0,0],[4,4]], queries = [[1,1],[1,0]]
-<strong>Output:</strong> [1,0]
-<strong>Explanation:</strong> We have the initial grid with all lamps turned off. In the above picture we see the grid after turning on the lamp at grid[0][0] then turning on the lamp at grid[4][4].
-The 0<sup>th</sup>&nbsp;query asks if the lamp at grid[1][1] is illuminated or not (the blue square). It is illuminated, so set ans[0] = 1. Then, we turn off all lamps in the red square.
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/19/illu_step1.jpg" style="width: 500px; height: 218px;" />
-The 1<sup>st</sup>&nbsp;query asks if the lamp at grid[1][0] is illuminated or not (the blue square). It is not illuminated, so set ans[1] = 0. Then, we turn off all lamps in the red rectangle.
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/19/illu_step2.jpg" style="width: 500px; height: 219px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, lamps = [[0,0],[4,4]], queries = [[1,1],[1,1]]
-<strong>Output:</strong> [1,1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, lamps = [[0,0],[0,4]], queries = [[0,4],[0,1],[1,4]]
-<strong>Output:</strong> [1,1,0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= lamps.length &lt;= 20000</code></li>
-	<li><code>0 &lt;= queries.length &lt;= 20000</code></li>
-	<li><code>lamps[i].length == 2</code></li>
-	<li><code>0 &lt;= row<sub>i</sub>, col<sub>i</sub> &lt; n</code></li>
-	<li><code>queries[j].length == 2</code></li>
-	<li><code>0 &lt;= row<sub>j</sub>, col<sub>j</sub> &lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [N-Queens](../n-queens) (Hard)
diff --git a/problems/grid-illumination/grid_illumination.go b/problems/grid-illumination/grid_illumination.go
deleted file mode 100644
index 1cb44cef5..000000000
--- a/problems/grid-illumination/grid_illumination.go
+++ /dev/null
@@ -1,90 +0,0 @@
-package problem1001
-
-func gridIllumination(N int, lamps [][]int, queries [][]int) []int {
-	l := newLights(N)
-	for _, lamp := range lamps {
-		x, y := lamp[0], lamp[1]
-		l.turnOn(x, y)
-	}
-
-	res := make([]int, 0, len(queries))
-	for _, cell := range queries {
-		x, y := cell[0], cell[1]
-		res = append(res, l.checkIlluminated(x, y))
-	}
-
-	return res
-}
-
-type lights struct {
-	h, v, ad, dd map[int]int
-	isOn         map[int]bool
-	n            int
-}
-
-func newLights(N int) *lights {
-	return &lights{
-		h:    make(map[int]int, 1024),
-		v:    make(map[int]int, 1024),
-		ad:   make(map[int]int, 1024),
-		dd:   make(map[int]int, 1024),
-		isOn: make(map[int]bool, 1024),
-		n:    N,
-	}
-}
-
-func (l *lights) turnOn(x, y int) {
-	l.h[x]++
-	l.v[y]++
-	l.ad[x+y]++
-	l.dd[x-y]++
-	l.isOn[x<<32+y] = true
-}
-
-func (l *lights) turnOff(x, y int) {
-	if x < 0 || l.n <= x ||
-		y < 0 || l.n <= y ||
-		!l.isOn[x<<32+y] {
-		return
-	}
-	l.isOn[x<<32+y] = false
-	l.h[x]--
-	l.v[y]--
-	l.ad[x+y]--
-	l.dd[x-y]--
-}
-
-func (l *lights) checkIlluminated(x, y int) int {
-	res := 0
-
-	if l.h[x] > 0 { // maybe [x,y-1] or [x,y] or [x,y+1] is On
-		res = 1
-		l.turnOff(x, y-1)
-		l.turnOff(x, y+1)
-		// leave [x,y] in the end
-	}
-
-	if l.v[y] > 0 {
-		res = 1
-		l.turnOff(x-1, y)
-		l.turnOff(x+1, y)
-	}
-
-	if l.ad[x+y] > 0 {
-		res = 1
-		l.turnOff(x-1, y+1)
-		l.turnOff(x+1, y-1)
-	}
-
-	if l.dd[x-y] > 0 {
-		res = 1
-		l.turnOff(x-1, y-1)
-		l.turnOff(x+1, y+1)
-	}
-
-	if res == 1 {
-		l.turnOff(x, y)
-	}
-
-	return res
-}
diff --git a/problems/group-anagrams/README.md b/problems/group-anagrams/README.md
deleted file mode 100644
index 03735262a..000000000
--- a/problems/group-anagrams/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rotate-image "Rotate Image")
-　　　　　　　　　　　　　　　　
-[Next >](../powx-n "Pow(x, n)")
-
-## [49. Group Anagrams (Medium)](https://leetcode.com/problems/group-anagrams "字母异位词分组")
-
-<p>Given an array of strings <code>strs</code>, group <strong>the anagrams</strong> together. You can return the answer in <strong>any order</strong>.</p>
-
-<p>An <strong>Anagram</strong> is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> strs = ["eat","tea","tan","ate","nat","bat"]
-<strong>Output:</strong> [["bat"],["nat","tan"],["ate","eat","tea"]]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> strs = [""]
-<strong>Output:</strong> [[""]]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> strs = ["a"]
-<strong>Output:</strong> [["a"]]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= strs.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= strs[i].length &lt;= 100</code></li>
-	<li><code>strs[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Valid Anagram](../valid-anagram) (Easy)
-  1. [Group Shifted Strings](../group-shifted-strings) (Medium)
diff --git a/problems/group-anagrams/group_anagrams.go b/problems/group-anagrams/group_anagrams.go
deleted file mode 100644
index ae0679d48..000000000
--- a/problems/group-anagrams/group_anagrams.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem49
diff --git a/problems/group-anagrams/group_anagrams_test.go b/problems/group-anagrams/group_anagrams_test.go
deleted file mode 100644
index ae0679d48..000000000
--- a/problems/group-anagrams/group_anagrams_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem49
diff --git a/problems/group-employees-of-the-same-salary/README.md b/problems/group-employees-of-the-same-salary/README.md
deleted file mode 100644
index 0b2f7fc0a..000000000
--- a/problems/group-employees-of-the-same-salary/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimize-product-sum-of-two-arrays "Minimize Product Sum of Two Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../substrings-of-size-three-with-distinct-characters "Substrings of Size Three with Distinct Characters")
-
-## [1875. Group Employees of the Same Salary (Medium)](https://leetcode.com/problems/group-employees-of-the-same-salary "将工资相同的雇员分组")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/group-employees-of-the-same-salary/mysql_schemas.sql b/problems/group-employees-of-the-same-salary/mysql_schemas.sql
deleted file mode 100644
index 9a2f41471..000000000
--- a/problems/group-employees-of-the-same-salary/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Employees (employee_id int, name varchar(30), salary int);
-Truncate table Employees;
-insert into Employees (employee_id, name, salary) values ('2', 'Meir', '3000');
-insert into Employees (employee_id, name, salary) values ('3', 'Michael', '3000');
-insert into Employees (employee_id, name, salary) values ('7', 'Addilyn', '7400');
-insert into Employees (employee_id, name, salary) values ('8', 'Juan', '6100');
-insert into Employees (employee_id, name, salary) values ('9', 'Kannon', '7400');
diff --git a/problems/group-shifted-strings/README.md b/problems/group-shifted-strings/README.md
deleted file mode 100644
index 1c029e1c7..000000000
--- a/problems/group-shifted-strings/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../strobogrammatic-number-iii "Strobogrammatic Number III")
-　　　　　　　　　　　　　　　　
-[Next >](../count-univalue-subtrees "Count Univalue Subtrees")
-
-## [249. Group Shifted Strings (Medium)](https://leetcode.com/problems/group-shifted-strings "移位字符串分组")
-
-<p>Given a string, we can &quot;shift&quot; each of its letter to its successive letter, for example: <code>&quot;abc&quot; -&gt; &quot;bcd&quot;</code>. We can keep &quot;shifting&quot; which forms the sequence:</p>
-
-<pre>
-&quot;abc&quot; -&gt; &quot;bcd&quot; -&gt; ... -&gt; &quot;xyz&quot;</pre>
-
-<p>Given a list of strings which contains only lowercase alphabets, group all strings that belong to the same shifting sequence.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-<b>Input:</b> <code>[&quot;abc&quot;, &quot;bcd&quot;, &quot;acef&quot;, &quot;xyz&quot;, &quot;az&quot;, &quot;ba&quot;, &quot;a&quot;, &quot;z&quot;],</code>
-<b>Output:</b> 
-[
-  [&quot;abc&quot;,&quot;bcd&quot;,&quot;xyz&quot;],
-  [&quot;az&quot;,&quot;ba&quot;],
-  [&quot;acef&quot;],
-  [&quot;a&quot;,&quot;z&quot;]
-]
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Group Anagrams](../group-anagrams) (Medium)
diff --git a/problems/group-shifted-strings/group_shifted_strings.go b/problems/group-shifted-strings/group_shifted_strings.go
deleted file mode 100644
index 9731cd966..000000000
--- a/problems/group-shifted-strings/group_shifted_strings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem249
diff --git a/problems/group-shifted-strings/group_shifted_strings_test.go b/problems/group-shifted-strings/group_shifted_strings_test.go
deleted file mode 100644
index 9731cd966..000000000
--- a/problems/group-shifted-strings/group_shifted_strings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem249
diff --git a/problems/group-sold-products-by-the-date/README.md b/problems/group-sold-products-by-the-date/README.md
deleted file mode 100644
index 6722eb2d8..000000000
--- a/problems/group-sold-products-by-the-date/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-ancestor-of-a-tree-node "Kth Ancestor of a Tree Node")
-　　　　　　　　　　　　　　　　
-[Next >](../clone-binary-tree-with-random-pointer "Clone Binary Tree With Random Pointer")
-
-## [1484. Group Sold Products By The Date (Easy)](https://leetcode.com/problems/group-sold-products-by-the-date "按日期分组销售产品")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/group-sold-products-by-the-date/mysql_schemas.sql b/problems/group-sold-products-by-the-date/mysql_schemas.sql
deleted file mode 100644
index bf1f0a1b3..000000000
--- a/problems/group-sold-products-by-the-date/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Activities (sell_date date, product varchar(20));
-Truncate table Activities;
-insert into Activities (sell_date, product) values ('2020-05-30', 'Headphone');
-insert into Activities (sell_date, product) values ('2020-06-01', 'Pencil');
-insert into Activities (sell_date, product) values ('2020-06-02', 'Mask');
-insert into Activities (sell_date, product) values ('2020-05-30', 'Basketball');
-insert into Activities (sell_date, product) values ('2020-06-01', 'Bible');
-insert into Activities (sell_date, product) values ('2020-06-02', 'Mask');
-insert into Activities (sell_date, product) values ('2020-05-30', 'T-Shirt');
diff --git a/problems/group-the-people-given-the-group-size-they-belong-to/README.md b/problems/group-the-people-given-the-group-size-they-belong-to/README.md
deleted file mode 100644
index dba3a9ead..000000000
--- a/problems/group-the-people-given-the-group-size-they-belong-to/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subtract-the-product-and-sum-of-digits-of-an-integer "Subtract the Product and Sum of Digits of an Integer")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-smallest-divisor-given-a-threshold "Find the Smallest Divisor Given a Threshold")
-
-## [1282. Group the People Given the Group Size They Belong To (Medium)](https://leetcode.com/problems/group-the-people-given-the-group-size-they-belong-to "用户分组")
-
-<p>There are <code>n</code> people&nbsp;that are split into some unknown number of groups. Each person is labeled with a&nbsp;<strong>unique ID</strong>&nbsp;from&nbsp;<code>0</code>&nbsp;to&nbsp;<code>n - 1</code>.</p>
-
-<p>You are given an integer array&nbsp;<code>groupSizes</code>, where <code>groupSizes[i]</code>&nbsp;is the size of the group that person&nbsp;<code>i</code>&nbsp;is in. For example, if&nbsp;<code>groupSizes[1] = 3</code>, then&nbsp;person&nbsp;<code>1</code>&nbsp;must be in a&nbsp;group of size&nbsp;<code>3</code>.</p>
-
-<p>Return&nbsp;<em>a list of groups&nbsp;such that&nbsp;each person&nbsp;<code>i</code>&nbsp;is in a group of size&nbsp;<code>groupSizes[i]</code></em>.</p>
-
-<p>Each person should&nbsp;appear in&nbsp;<strong>exactly one group</strong>,&nbsp;and every person must be in a group. If there are&nbsp;multiple answers, <strong>return any of them</strong>. It is <strong>guaranteed</strong> that there will be <strong>at least one</strong> valid solution for the given input.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> groupSizes = [3,3,3,3,3,1,3]
-<strong>Output:</strong> [[5],[0,1,2],[3,4,6]]
-<b>Explanation:</b> 
-The first group is [5]. The size is 1, and groupSizes[5] = 1.
-The second group is [0,1,2]. The size is 3, and groupSizes[0] = groupSizes[1] = groupSizes[2] = 3.
-The third group is [3,4,6]. The size is 3, and groupSizes[3] = groupSizes[4] = groupSizes[6] = 3.
-Other possible solutions are [[2,1,6],[5],[0,4,3]] and [[5],[0,6,2],[4,3,1]].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> groupSizes = [2,1,3,3,3,2]
-<strong>Output:</strong> [[1],[0,5],[2,3,4]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>groupSizes.length == n</code></li>
-	<li><code>1 &lt;= n&nbsp;&lt;= 500</code></li>
-	<li><code>1 &lt;=&nbsp;groupSizes[i] &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Put people's IDs with same groupSize into buckets, then split each bucket into groups.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Greedy fill until you need a new group.
-</details>
diff --git a/problems/groups-of-special-equivalent-strings/README.md b/problems/groups-of-special-equivalent-strings/README.md
deleted file mode 100644
index e4a7bbf4f..000000000
--- a/problems/groups-of-special-equivalent-strings/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../surface-area-of-3d-shapes "Surface Area of 3D Shapes")
-　　　　　　　　　　　　　　　　
-[Next >](../all-possible-full-binary-trees "All Possible Full Binary Trees")
-
-## [893. Groups of Special-Equivalent Strings (Medium)](https://leetcode.com/problems/groups-of-special-equivalent-strings "特殊等价字符串组")
-
-<p>You are given an array of strings of the same length <code>words</code>.</p>
-
-<p>In one <strong>move</strong>, you can swap any two even indexed characters or any two odd indexed characters of a string <code>words[i]</code>.</p>
-
-<p>Two strings <code>words[i]</code> and <code>words[j]</code> are <strong>special-equivalent</strong> if after any number of moves, <code>words[i] == words[j]</code>.</p>
-
-<ul>
-	<li>For example, <code>words[i] = &quot;zzxy&quot;</code> and <code>words[j] = &quot;xyzz&quot;</code> are <strong>special-equivalent</strong> because we may make the moves <code>&quot;zzxy&quot; -&gt; &quot;xzzy&quot; -&gt; &quot;xyzz&quot;</code>.</li>
-</ul>
-
-<p>A <strong>group of special-equivalent strings</strong> from <code>words</code> is a non-empty subset of words such that:</p>
-
-<ul>
-	<li>Every pair of strings in the group are special equivalent, and</li>
-	<li>The group is the largest size possible (i.e., there is not a string <code>words[i]</code> not in the group such that <code>words[i]</code> is special-equivalent to every string in the group).</li>
-</ul>
-
-<p>Return <em>the number of <strong>groups of special-equivalent strings</strong> from </em><code>words</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;abcd&quot;,&quot;cdab&quot;,&quot;cbad&quot;,&quot;xyzz&quot;,&quot;zzxy&quot;,&quot;zzyx&quot;]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-One group is [&quot;abcd&quot;, &quot;cdab&quot;, &quot;cbad&quot;], since they are all pairwise special equivalent, and none of the other strings is all pairwise special equivalent to these.
-The other two groups are [&quot;xyzz&quot;, &quot;zzxy&quot;] and [&quot;zzyx&quot;].
-Note that in particular, &quot;zzxy&quot; is not special equivalent to &quot;zzyx&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;abc&quot;,&quot;acb&quot;,&quot;bac&quot;,&quot;bca&quot;,&quot;cab&quot;,&quot;cba&quot;]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 20</code></li>
-	<li><code>words[i]</code> consist of lowercase English letters.</li>
-	<li>All the strings are of the same length.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/groups-of-special-equivalent-strings/groups_of_special_equivalent_strings.go b/problems/groups-of-special-equivalent-strings/groups_of_special_equivalent_strings.go
deleted file mode 100644
index f047c1d21..000000000
--- a/problems/groups-of-special-equivalent-strings/groups_of_special_equivalent_strings.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem893
-
-func numSpecialEquivGroups(A []string) int {
-	m := make(map[[52]int]bool)
-	for _, s := range A {
-		var count [52]int
-		for i, char := range s {
-			count[int(char)-'a'+26*(i%2)]++
-		}
-		m[count] = true
-	}
-	return len(m)
-}
diff --git a/problems/groups-of-special-equivalent-strings/groups_of_special_equivalent_strings_test.go b/problems/groups-of-special-equivalent-strings/groups_of_special_equivalent_strings_test.go
deleted file mode 100644
index be141f771..000000000
--- a/problems/groups-of-special-equivalent-strings/groups_of_special_equivalent_strings_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem893
-
-import "testing"
-
-type testType struct {
-	in   []string
-	want int
-}
-
-func TestNumSpecialEquivGroups(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []string{"a", "b", "c", "a", "c", "c"},
-			want: 3,
-		},
-		{
-			in:   []string{"aa", "bb", "ab", "ba"},
-			want: 4,
-		},
-		{
-			in:   []string{"abc", "acb", "bac", "bca", "cab", "cba"},
-			want: 3,
-		},
-		{
-			in:   []string{"abcd", "cdab", "adcb", "cbad"},
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := numSpecialEquivGroups(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/groups-of-strings/README.md b/problems/groups-of-strings/README.md
deleted file mode 100644
index 0cc7e7afb..000000000
--- a/problems/groups-of-strings/README.md
+++ /dev/null
@@ -1,96 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-substring-with-given-hash-value "Find Substring With Given Hash Value")
-　　　　　　　　　　　　　　　　
-[Next >](../amount-of-new-area-painted-each-day "Amount of New Area Painted Each Day")
-
-## [2157. Groups of Strings (Hard)](https://leetcode.com/problems/groups-of-strings "字符串分组")
-
-<p>You are given a <strong>0-indexed</strong> array of strings <code>words</code>. Each string consists of <strong>lowercase English letters</strong> only. No letter occurs more than once in any string of <code>words</code>.</p>
-
-<p>Two strings <code>s1</code> and <code>s2</code> are said to be <strong>connected</strong> if the set of letters of <code>s2</code> can be obtained from the set of letters of <code>s1</code> by any <strong>one</strong> of the following operations:</p>
-
-<ul>
-	<li>Adding exactly one letter to the set of the letters of <code>s1</code>.</li>
-	<li>Deleting exactly one letter from the set of the letters of <code>s1</code>.</li>
-	<li>Replacing exactly one letter from the set of the letters of <code>s1</code> with any letter, <strong>including</strong> itself.</li>
-</ul>
-
-<p>The array <code>words</code> can be divided into one or more non-intersecting <strong>groups</strong>. A string belongs to a group if any <strong>one</strong> of the following is true:</p>
-
-<ul>
-	<li>It is connected to <strong>at least one</strong> other string of the group.</li>
-	<li>It is the <strong>only</strong> string present in the group.</li>
-</ul>
-
-<p>Note that the strings in <code>words</code> should be grouped in such a manner that a string belonging to a group cannot be connected to a string present in any other group. It can be proved that such an arrangement is always unique.</p>
-
-<p>Return <em>an array</em> <code>ans</code> <em>of size</em> <code>2</code> <em>where:</em></p>
-
-<ul>
-	<li><code>ans[0]</code> <em>is the <strong>maximum number</strong> of groups</em> <code>words</code> <em>can be divided into, and</em></li>
-	<li><code>ans[1]</code> <em>is the <strong>size of the largest</strong> group</em>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;a&quot;,&quot;b&quot;,&quot;ab&quot;,&quot;cde&quot;]
-<strong>Output:</strong> [2,3]
-<strong>Explanation:</strong>
-- words[0] can be used to obtain words[1] (by replacing &#39;a&#39; with &#39;b&#39;), and words[2] (by adding &#39;b&#39;). So words[0] is connected to words[1] and words[2].
-- words[1] can be used to obtain words[0] (by replacing &#39;b&#39; with &#39;a&#39;), and words[2] (by adding &#39;a&#39;). So words[1] is connected to words[0] and words[2].
-- words[2] can be used to obtain words[0] (by deleting &#39;b&#39;), and words[1] (by deleting &#39;a&#39;). So words[2] is connected to words[0] and words[1].
-- words[3] is not connected to any string in words.
-Thus, words can be divided into 2 groups [&quot;a&quot;,&quot;b&quot;,&quot;ab&quot;] and [&quot;cde&quot;]. The size of the largest group is 3.  
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;a&quot;,&quot;ab&quot;,&quot;abc&quot;]
-<strong>Output:</strong> [1,3]
-<strong>Explanation:</strong>
-- words[0] is connected to words[1].
-- words[1] is connected to words[0] and words[2].
-- words[2] is connected to words[1].
-Since all strings are connected to each other, they should be grouped together.
-Thus, the size of the largest group is 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 26</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters only.</li>
-	<li>No letter occurs more than once in <code>words[i]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we build a graph from words, where there exists an edge between nodes i and j if words[i] and words[j] are connected?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The problem now boils down to finding the total number of components and the size of the largest component in the graph.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How can we use bit masking to reduce the search space while adding edges to node i?
-</details>
diff --git a/problems/grumpy-bookstore-owner/README.md b/problems/grumpy-bookstore-owner/README.md
deleted file mode 100644
index 046dc245c..000000000
--- a/problems/grumpy-bookstore-owner/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../height-checker "Height Checker")
-　　　　　　　　　　　　　　　　
-[Next >](../previous-permutation-with-one-swap "Previous Permutation With One Swap")
-
-## [1052. Grumpy Bookstore Owner (Medium)](https://leetcode.com/problems/grumpy-bookstore-owner "爱生气的书店老板")
-
-<p>There is a bookstore owner that has a store open for <code>n</code> minutes. Every minute, some number of customers enter the store. You are given an integer array <code>customers</code> of length <code>n</code> where <code>customers[i]</code> is the number of the customer that enters the store at the start of the <code>i<sup>th</sup></code> minute and all those customers leave after the end of that minute.</p>
-
-<p>On some minutes, the bookstore owner is grumpy. You are given a binary array grumpy where <code>grumpy[i]</code> is <code>1</code> if the bookstore owner is grumpy during the <code>i<sup>th</sup></code> minute, and is <code>0</code> otherwise.</p>
-
-<p>When the bookstore owner is grumpy, the customers of that minute are not satisfied, otherwise, they are satisfied.</p>
-
-<p>The bookstore owner knows a secret technique to keep themselves not grumpy for <code>minutes</code> consecutive minutes, but can only use it once.</p>
-
-<p>Return <em>the maximum number of customers that can be satisfied throughout the day</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> customers = [1,0,1,2,1,1,7,5], grumpy = [0,1,0,1,0,1,0,1], minutes = 3
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> The bookstore owner keeps themselves not grumpy for the last 3 minutes. 
-The maximum number of customers that can be satisfied = 1 + 1 + 1 + 1 + 7 + 5 = 16.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> customers = [1], grumpy = [0], minutes = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == customers.length == grumpy.length</code></li>
-	<li><code>1 &lt;= minutes &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= customers[i] &lt;= 1000</code></li>
-	<li><code>grumpy[i]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Say the store owner uses their power in minute 1 to X and we have some answer A.  If they instead use their power from minute 2 to X+1, we only have to use data from minutes 1, 2, X and X+1 to update our answer A.
-</details>
diff --git a/problems/grumpy-bookstore-owner/grumpy_bookstore_owner.go b/problems/grumpy-bookstore-owner/grumpy_bookstore_owner.go
deleted file mode 100644
index 6e992ad52..000000000
--- a/problems/grumpy-bookstore-owner/grumpy_bookstore_owner.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem1052
-
-func maxSatisfied(customers []int, grumpy []int, X int) int {
-	n := len(customers)
-	satisfied, dis, maxDis := 0, 0, 0
-	for i := 0; i < n; i++ {
-		satisfied += customers[i] * (1 - grumpy[i])
-		dis += customers[i] * grumpy[i]
-		if i-X >= 0 {
-			// NOTICE: len(A[i-X+1:i+1]) = X
-			// for keeping dis's length is X
-			// subscrip A[i-X]*grumpy[i-X]
-			dis -= customers[i-X] * grumpy[i-X]
-		}
-		maxDis = max(maxDis, dis)
-	}
-	return satisfied + maxDis
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/guess-number-higher-or-lower-ii/README.md b/problems/guess-number-higher-or-lower-ii/README.md
deleted file mode 100644
index 26a48172e..000000000
--- a/problems/guess-number-higher-or-lower-ii/README.md
+++ /dev/null
@@ -1,113 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../guess-number-higher-or-lower "Guess Number Higher or Lower")
-　　　　　　　　　　　　　　　　
-[Next >](../wiggle-subsequence "Wiggle Subsequence")
-
-## [375. Guess Number Higher or Lower II (Medium)](https://leetcode.com/problems/guess-number-higher-or-lower-ii "猜数字大小 II")
-
-<p>We are playing the Guessing Game. The game will work as follows:</p>
-
-<ol>
-	<li>I pick a number between&nbsp;<code>1</code>&nbsp;and&nbsp;<code>n</code>.</li>
-	<li>You guess a number.</li>
-	<li>If you guess the right number, <strong>you win the game</strong>.</li>
-	<li>If you guess the wrong number, then I will tell you whether the number I picked is <strong>higher or lower</strong>, and you will continue guessing.</li>
-	<li>Every time you guess a wrong number&nbsp;<code>x</code>, you will pay&nbsp;<code>x</code>&nbsp;dollars. If you run out of money, <strong>you lose the game</strong>.</li>
-</ol>
-
-<p>Given a particular&nbsp;<code>n</code>, return&nbsp;<em>the minimum amount of money you need to&nbsp;<strong>guarantee a win regardless of what number I pick</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/10/graph.png" style="width: 505px; height: 388px;" />
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> The winning strategy is as follows:
-- The range is [1,10]. Guess 7.
-&nbsp;   - If this is my number, your total is $0. Otherwise, you pay $7.
-&nbsp;   - If my number is higher, the range is [8,10]. Guess 9.
-&nbsp;       - If this is my number, your total is $7. Otherwise, you pay $9.
-&nbsp;       - If my number is higher, it must be 10. Guess 10. Your total is $7 + $9 = $16.
-&nbsp;       - If my number is lower, it must be 8. Guess 8. Your total is $7 + $9 = $16.
-&nbsp;   - If my number is lower, the range is [1,6]. Guess 3.
-&nbsp;       - If this is my number, your total is $7. Otherwise, you pay $3.
-&nbsp;       - If my number is higher, the range is [4,6]. Guess 5.
-&nbsp;           - If this is my number, your total is $7 + $3 = $10. Otherwise, you pay $5.
-&nbsp;           - If my number is higher, it must be 6. Guess 6. Your total is $7 + $3 + $5 = $15.
-&nbsp;           - If my number is lower, it must be 4. Guess 4. Your total is $7 + $3 + $5 = $15.
-&nbsp;       - If my number is lower, the range is [1,2]. Guess 1.
-&nbsp;           - If this is my number, your total is $7 + $3 = $10. Otherwise, you pay $1.
-&nbsp;           - If my number is higher, it must be 2. Guess 2. Your total is $7 + $3 + $1 = $11.
-The worst case in all these scenarios is that you pay $16. Hence, you only need $16 to guarantee a win.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>&nbsp;There is only one possible number, so you can guess 1 and not have to pay anything.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>&nbsp;There are two possible numbers, 1 and 2.
-- Guess 1.
-&nbsp;   - If this is my number, your total is $0. Otherwise, you pay $1.
-&nbsp;   - If my number is higher, it must be 2. Guess 2. Your total is $1.
-The worst case is that you pay $1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 200</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Similar Questions
-  1. [Flip Game II](../flip-game-ii) (Medium)
-  1. [Guess Number Higher or Lower](../guess-number-higher-or-lower) (Easy)
-  1. [Can I Win](../can-i-win) (Medium)
-  1. [Find K Closest Elements](../find-k-closest-elements) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The best strategy to play the game is to minimize the maximum loss you could possibly face. Another strategy is to minimize the expected loss. Here, we are interested in the <b>first</b> scenario.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Take a small example (n = 3). What do you end up paying in the worst case?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Check out <a href="https://en.wikipedia.org/wiki/Minimax">this article</a> if you're still stuck.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The purely recursive implementation of minimax would be worthless for even a small n. You MUST use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-As a follow-up, how would you modify your code to solve the problem of minimizing the expected loss, instead of the worst-case loss?
-</details>
diff --git a/problems/guess-number-higher-or-lower-ii/guess_number_higher_or_lower_ii.go b/problems/guess-number-higher-or-lower-ii/guess_number_higher_or_lower_ii.go
deleted file mode 100644
index ba6bfd79f..000000000
--- a/problems/guess-number-higher-or-lower-ii/guess_number_higher_or_lower_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem375
diff --git a/problems/guess-number-higher-or-lower-ii/guess_number_higher_or_lower_ii_test.go b/problems/guess-number-higher-or-lower-ii/guess_number_higher_or_lower_ii_test.go
deleted file mode 100644
index ba6bfd79f..000000000
--- a/problems/guess-number-higher-or-lower-ii/guess_number_higher_or_lower_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem375
diff --git a/problems/guess-number-higher-or-lower/README.md b/problems/guess-number-higher-or-lower/README.md
deleted file mode 100644
index 52aa4fcb3..000000000
--- a/problems/guess-number-higher-or-lower/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-k-pairs-with-smallest-sums "Find K Pairs with Smallest Sums")
-　　　　　　　　　　　　　　　　
-[Next >](../guess-number-higher-or-lower-ii "Guess Number Higher or Lower II")
-
-## [374. Guess Number Higher or Lower (Easy)](https://leetcode.com/problems/guess-number-higher-or-lower "猜数字大小")
-
-<p>We are playing the Guess Game. The game is as follows:</p>
-
-<p>I pick a number from <code>1</code> to <code>n</code>. You have to guess which number I picked.</p>
-
-<p>Every time you guess wrong, I will tell you whether the number I picked is higher or lower than your guess.</p>
-
-<p>You call a pre-defined API <code>int guess(int num)</code>, which returns three possible results:</p>
-
-<ul>
-	<li><code>-1</code>: Your guess is higher than the number I picked (i.e. <code>num &gt; pick</code>).</li>
-	<li><code>1</code>: Your guess is lower than the number I picked (i.e. <code>num &lt; pick</code>).</li>
-	<li><code>0</code>: your guess is equal to the number I picked (i.e. <code>num == pick</code>).</li>
-</ul>
-
-<p>Return <em>the number that I picked</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10, pick = 6
-<strong>Output:</strong> 6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, pick = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, pick = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>1 &lt;= pick &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Similar Questions
-  1. [First Bad Version](../first-bad-version) (Easy)
-  1. [Guess Number Higher or Lower II](../guess-number-higher-or-lower-ii) (Medium)
-  1. [Find K Closest Elements](../find-k-closest-elements) (Medium)
diff --git a/problems/guess-number-higher-or-lower/guess_number_higher_or_lower.go b/problems/guess-number-higher-or-lower/guess_number_higher_or_lower.go
deleted file mode 100644
index 4bed9a8ed..000000000
--- a/problems/guess-number-higher-or-lower/guess_number_higher_or_lower.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem374
diff --git a/problems/guess-number-higher-or-lower/guess_number_higher_or_lower.py b/problems/guess-number-higher-or-lower/guess_number_higher_or_lower.py
deleted file mode 100755
index 11f2af6c6..000000000
--- a/problems/guess-number-higher-or-lower/guess_number_higher_or_lower.py
+++ /dev/null
@@ -1,14 +0,0 @@
-#!/usr/bin/env python
-
-# The guess API is already defined for you.
-# @param num, your guess
-# @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
-# def guess(num):
-
-class Solution(object):
-    def guessNumber(self, n):
-        """
-        :type n: int
-        :rtype: int
-        """
-        
\ No newline at end of file
diff --git a/problems/guess-number-higher-or-lower/guess_number_higher_or_lower_test.go b/problems/guess-number-higher-or-lower/guess_number_higher_or_lower_test.go
deleted file mode 100644
index 4bed9a8ed..000000000
--- a/problems/guess-number-higher-or-lower/guess_number_higher_or_lower_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem374
diff --git a/problems/guess-the-majority-in-a-hidden-array/README.md b/problems/guess-the-majority-in-a-hidden-array/README.md
deleted file mode 100644
index 633b3be7d..000000000
--- a/problems/guess-the-majority-in-a-hidden-array/README.md
+++ /dev/null
@@ -1,25 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../get-the-maximum-score "Get the Maximum Score")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-missing-positive-number "Kth Missing Positive Number")
-
-## [1538. Guess the Majority in a Hidden Array (Medium)](https://leetcode.com/problems/guess-the-majority-in-a-hidden-array "找出隐藏数组中出现次数最多的元素")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you find that 2 indexes in the array (id1, id2) have the same value (nums [id1] == nums [id2]), you could infer the values of (x, y) based on the results of query (id1, id2, x, y).
-</details>
diff --git a/problems/guess-the-word/README.md b/problems/guess-the-word/README.md
deleted file mode 100644
index 97fb5c1ad..000000000
--- a/problems/guess-the-word/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-array-into-fibonacci-sequence "Split Array into Fibonacci Sequence")
-　　　　　　　　　　　　　　　　
-[Next >](../backspace-string-compare "Backspace String Compare")
-
-## [843. Guess the Word (Hard)](https://leetcode.com/problems/guess-the-word "猜猜这个单词")
-
-<p>This is an <strong><em>interactive problem</em></strong>.</p>
-
-<p>You are given an array of <strong>unique</strong> strings <code>wordlist</code> where <code>wordlist[i]</code> is <code>6</code> letters long, and one word in this list is chosen as <code>secret</code>.</p>
-
-<p>You may call <code>Master.guess(word)</code> to guess a word. The guessed word should have type <code>string</code> and must be from the original list with <code>6</code> lowercase letters.</p>
-
-<p>This function returns an <code>integer</code> type, representing the number of exact matches (value and position) of your guess to the <code>secret</code> word. Also, if your guess is not in the given wordlist, it will return <code>-1</code> instead.</p>
-
-<p>For each test case, you have exactly <code>10</code> guesses to guess the word. At the end of any number of calls, if you have made <code>10</code> or fewer calls to <code>Master.guess</code> and at least one of these guesses was <code>secret</code>, then you pass the test case.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> secret = &quot;acckzz&quot;, wordlist = [&quot;acckzz&quot;,&quot;ccbazz&quot;,&quot;eiowzz&quot;,&quot;abcczz&quot;], numguesses = 10
-<strong>Output:</strong> You guessed the secret word correctly.
-<strong>Explanation:</strong>
-master.guess(&quot;aaaaaa&quot;) returns -1, because &quot;aaaaaa&quot; is not in wordlist.
-master.guess(&quot;acckzz&quot;) returns 6, because &quot;acckzz&quot; is secret and has all 6 matches.
-master.guess(&quot;ccbazz&quot;) returns 3, because &quot;ccbazz&quot; has 3 matches.
-master.guess(&quot;eiowzz&quot;) returns 2, because &quot;eiowzz&quot; has 2 matches.
-master.guess(&quot;abcczz&quot;) returns 4, because &quot;abcczz&quot; has 4 matches.
-We made 5 calls to master.guess and one of them was the secret, so we pass the test case.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> secret = &quot;hamada&quot;, wordlist = [&quot;hamada&quot;,&quot;khaled&quot;], numguesses = 10
-<strong>Output:</strong> You guessed the secret word correctly.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= wordlist.length &lt;= 100</code></li>
-	<li><code>wordlist[i].length == 6</code></li>
-	<li><code>wordlist[i]</code> consist of lowercase English letters.</li>
-	<li>All the strings of <code>wordlist</code> are <strong>unique</strong>.</li>
-	<li><code>secret</code> exists in <code>wordlist</code>.</li>
-	<li><code>numguesses == 10</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
diff --git a/problems/guess-the-word/guess_the_word.go b/problems/guess-the-word/guess_the_word.go
deleted file mode 100644
index 04762a212..000000000
--- a/problems/guess-the-word/guess_the_word.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem843
diff --git a/problems/guess-the-word/guess_the_word_test.go b/problems/guess-the-word/guess_the_word_test.go
deleted file mode 100644
index 04762a212..000000000
--- a/problems/guess-the-word/guess_the_word_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem843
diff --git a/problems/h-index-ii/README.md b/problems/h-index-ii/README.md
deleted file mode 100644
index 4952cf45a..000000000
--- a/problems/h-index-ii/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../h-index "H-Index")
-　　　　　　　　　　　　　　　　
-[Next >](../paint-fence "Paint Fence")
-
-## [275. H-Index II (Medium)](https://leetcode.com/problems/h-index-ii "H 指数 II")
-
-<p>Given an array of integers <code>citations</code> where <code>citations[i]</code> is the number of citations a researcher received for their <code>i<sup>th</sup></code> paper and <code>citations</code>&nbsp;is sorted in an <strong>ascending order</strong>, return compute the researcher&#39;s <code>h</code><strong>-index</strong>.</p>
-
-<p>According to the <a href="https://en.wikipedia.org/wiki/H-index" target="_blank">definition of h-index on Wikipedia</a>: A scientist has an index <code>h</code> if <code>h</code> of their <code>n</code> papers have at least <code>h</code> citations each, and the other <code>n &minus; h</code> papers have no more than <code>h</code> citations each.</p>
-
-<p>If there are several possible values for <code>h</code>, the maximum one is taken as the <code>h</code><strong>-index</strong>.</p>
-
-<p>You must write an algorithm that runs in logarithmic time.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> citations = [0,1,3,5,6]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> [0,1,3,5,6] means the researcher has 5 papers in total and each of them had received 0, 1, 3, 5, 6 citations respectively.
-Since the researcher has 3 papers with at least 3 citations each and the remaining two with no more than 3 citations each, their h-index is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> citations = [1,2,100]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == citations.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= citations[i] &lt;= 1000</code></li>
-	<li><code>citations</code> is sorted in <strong>ascending order</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [H-Index](../h-index) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Expected runtime complexity is in <i>O</i>(log <i>n</i>) and the input is sorted.
-</details>
diff --git a/problems/h-index-ii/h_index_ii.go b/problems/h-index-ii/h_index_ii.go
deleted file mode 100644
index 064b2ccc0..000000000
--- a/problems/h-index-ii/h_index_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem275
diff --git a/problems/h-index-ii/h_index_ii_test.go b/problems/h-index-ii/h_index_ii_test.go
deleted file mode 100644
index 064b2ccc0..000000000
--- a/problems/h-index-ii/h_index_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem275
diff --git a/problems/h-index/README.md b/problems/h-index/README.md
deleted file mode 100644
index 1ac775cba..000000000
--- a/problems/h-index/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../integer-to-english-words "Integer to English Words")
-　　　　　　　　　　　　　　　　
-[Next >](../h-index-ii "H-Index II")
-
-## [274. H-Index (Medium)](https://leetcode.com/problems/h-index "H 指数")
-
-<p>Given an array of integers <code>citations</code> where <code>citations[i]</code> is the number of citations a researcher received for their <code>i<sup>th</sup></code> paper, return compute the researcher&#39;s <code>h</code><strong>-index</strong>.</p>
-
-<p>According to the <a href="https://en.wikipedia.org/wiki/H-index" target="_blank">definition of h-index on Wikipedia</a>: A scientist has an index <code>h</code> if <code>h</code> of their <code>n</code> papers have at least <code>h</code> citations each, and the other <code>n &minus; h</code> papers have no more than <code>h</code> citations each.</p>
-
-<p>If there are several possible values for <code>h</code>, the maximum one is taken as the <code>h</code><strong>-index</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> citations = [3,0,6,1,5]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> [3,0,6,1,5] means the researcher has 5 papers in total and each of them had received 3, 0, 6, 1, 5 citations respectively.
-Since the researcher has 3 papers with at least 3 citations each and the remaining two with no more than 3 citations each, their h-index is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> citations = [1,3,1]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == citations.length</code></li>
-	<li><code>1 &lt;= n &lt;= 5000</code></li>
-	<li><code>0 &lt;= citations[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Counting Sort](../../tag/counting-sort/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [H-Index II](../h-index-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-An easy approach is to sort the array first.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What are the possible values of h-index?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-A faster approach is to use extra space.
-</details>
diff --git a/problems/h-index/h_index.go b/problems/h-index/h_index.go
deleted file mode 100644
index cedc17adf..000000000
--- a/problems/h-index/h_index.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem274
diff --git a/problems/h-index/h_index_test.go b/problems/h-index/h_index_test.go
deleted file mode 100644
index cedc17adf..000000000
--- a/problems/h-index/h_index_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem274
diff --git a/problems/hamming-distance/README.md b/problems/hamming-distance/README.md
deleted file mode 100644
index 1e18c1f93..000000000
--- a/problems/hamming-distance/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lfu-cache "LFU Cache")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-moves-to-equal-array-elements-ii "Minimum Moves to Equal Array Elements II")
-
-## [461. Hamming Distance (Easy)](https://leetcode.com/problems/hamming-distance "汉明距离")
-
-<p>The <a href="https://en.wikipedia.org/wiki/Hamming_distance" target="_blank">Hamming distance</a> between two integers is the number of positions at which the corresponding bits are different.</p>
-
-<p>Given two integers <code>x</code> and <code>y</code>, return <em>the <strong>Hamming distance</strong> between them</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 1, y = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-1   (0 0 0 1)
-4   (0 1 0 0)
-       &uarr;   &uarr;
-The above arrows point to positions where the corresponding bits are different.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 3, y = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;=&nbsp;x, y &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Number of 1 Bits](../number-of-1-bits) (Easy)
-  1. [Total Hamming Distance](../total-hamming-distance) (Medium)
diff --git a/problems/hamming-distance/hamming_distance.go b/problems/hamming-distance/hamming_distance.go
deleted file mode 100644
index 22b0e3f62..000000000
--- a/problems/hamming-distance/hamming_distance.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package problem461
-
-func hammingDistance(x int, y int) int {
-	ans, n := 0, x^y
-	for n > 0 {
-		ans, n = ans+1, n&(n-1)
-	}
-	return ans
-}
diff --git a/problems/hamming-distance/hamming_distance_test.go b/problems/hamming-distance/hamming_distance_test.go
deleted file mode 100644
index c932a0c13..000000000
--- a/problems/hamming-distance/hamming_distance_test.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem461
-
-import "testing"
-
-type testType struct {
-	x    int
-	y    int
-	want int
-}
-
-func TestHammingDistance(t *testing.T) {
-	tests := [...]testType{
-		{
-			x:    1,
-			y:    4,
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := hammingDistance(tt.x, tt.y)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.x, tt.y, got, tt.want)
-		}
-	}
-}
diff --git a/problems/hand-of-straights/README.md b/problems/hand-of-straights/README.md
deleted file mode 100644
index 676fad6b1..000000000
--- a/problems/hand-of-straights/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-mountain-in-array "Longest Mountain in Array")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-path-visiting-all-nodes "Shortest Path Visiting All Nodes")
-
-## [846. Hand of Straights (Medium)](https://leetcode.com/problems/hand-of-straights "一手顺子")
-
-<p>Alice has some number of cards and she wants to rearrange the cards into groups so that each group is of size <code>groupSize</code>, and consists of <code>groupSize</code> consecutive cards.</p>
-
-<p>Given an integer array <code>hand</code> where <code>hand[i]</code> is the value written on the <code>i<sup>th</sup></code> card and an integer <code>groupSize</code>, return <code>true</code> if she can rearrange the cards, or <code>false</code> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> hand = [1,2,3,6,2,3,4,7,8], groupSize = 3
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Alice&#39;s hand can be rearranged as [1,2,3],[2,3,4],[6,7,8]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> hand = [1,2,3,4,5], groupSize = 4
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Alice&#39;s hand can not be rearranged into groups of 4.
-
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= hand.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= hand[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= groupSize &lt;= hand.length</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 1296: <a href="https://leetcode.com/problems/divide-array-in-sets-of-k-consecutive-numbers/" target="_blank">https://leetcode.com/problems/divide-array-in-sets-of-k-consecutive-numbers/</a></p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/hand-of-straights/hand_of_straights.go b/problems/hand-of-straights/hand_of_straights.go
deleted file mode 100644
index 74721fed3..000000000
--- a/problems/hand-of-straights/hand_of_straights.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem846
diff --git a/problems/hand-of-straights/hand_of_straights_test.go b/problems/hand-of-straights/hand_of_straights_test.go
deleted file mode 100644
index 74721fed3..000000000
--- a/problems/hand-of-straights/hand_of_straights_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem846
diff --git a/problems/handshakes-that-dont-cross/README.md b/problems/handshakes-that-dont-cross/README.md
deleted file mode 100644
index 3817221f4..000000000
--- a/problems/handshakes-that-dont-cross/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../synonymous-sentences "Synonymous Sentences")
-　　　　　　　　　　　　　　　　
-[Next >](../shift-2d-grid "Shift 2D Grid")
-
-## [1259. Handshakes That Don't Cross (Hard)](https://leetcode.com/problems/handshakes-that-dont-cross "不相交的握手")
-
-<p>You are given an&nbsp;<strong>even</strong> number of people <code>num_people</code>&nbsp;that stand around a circle and each person shakes hands&nbsp;with someone else, so that there are <code>num_people / 2</code> handshakes total.</p>
-
-<p>Return the number of ways these handshakes could occur such that none of the handshakes cross.</p>
-
-<p>Since this number could be very big, return the answer <strong>mod&nbsp;<code>10^9 + 7</code></strong></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num_people = 2
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/07/11/5125_example_2.png" style="width: 651px; height: 311px;" /></p>
-
-<pre>
-<strong>Input:</strong> num_people = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are two ways to do it, the first way is [(1,2),(3,4)] and the second one is [(2,3),(4,1)].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/07/11/5125_example_3.png" style="width: 664px; height: 992px;" /></p>
-
-<pre>
-<strong>Input:</strong> num_people = 6
-<strong>Output:</strong> 5
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> num_people = 8
-<strong>Output:</strong> 14
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= num_people &lt;= 1000</code></li>
-	<li><code>num_people % 2 == 0</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let dp[n] be the number of ways that n people can handshake.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Then fix a person as a pivot and turn for every other person who will have a handshake, the answer is the sum of the products of the new two subproblems.
-</details>
diff --git a/problems/happy-number/README.md b/problems/happy-number/README.md
deleted file mode 100644
index 3f683e060..000000000
--- a/problems/happy-number/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bitwise-and-of-numbers-range "Bitwise AND of Numbers Range")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-linked-list-elements "Remove Linked List Elements")
-
-## [202. Happy Number (Easy)](https://leetcode.com/problems/happy-number "快乐数")
-
-<p>Write an algorithm to determine if a number <code>n</code> is happy.</p>
-
-<p>A <strong>happy number</strong> is a number defined by the following process:</p>
-
-<ul>
-	<li>Starting with any positive integer, replace the number by the sum of the squares of its digits.</li>
-	<li>Repeat the process until the number equals 1 (where it will stay), or it <strong>loops endlessly in a cycle</strong> which does not include 1.</li>
-	<li>Those numbers for which this process <strong>ends in 1</strong> are happy.</li>
-</ul>
-
-<p>Return <code>true</code> <em>if</em> <code>n</code> <em>is a happy number, and</em> <code>false</code> <em>if not</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 19
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-1<sup>2</sup> + 9<sup>2</sup> = 82
-8<sup>2</sup> + 2<sup>2</sup> = 68
-6<sup>2</sup> + 8<sup>2</sup> = 100
-1<sup>2</sup> + 0<sup>2</sup> + 0<sup>2</sup> = 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Linked List Cycle](../linked-list-cycle) (Easy)
-  1. [Add Digits](../add-digits) (Easy)
-  1. [Ugly Number](../ugly-number) (Easy)
diff --git a/problems/happy-number/happy_number.go b/problems/happy-number/happy_number.go
deleted file mode 100644
index 13d4265f9..000000000
--- a/problems/happy-number/happy_number.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem202
-
-func isHappy(n int) bool {
-	m := make(map[int]bool)
-	for n != 1 && !m[n] {
-		m[n] = true
-		sum := 0
-		for n > 0 {
-			x := n % 10
-			sum += x * x
-			n /= 10
-		}
-		n = sum
-	}
-	return n == 1
-}
diff --git a/problems/happy-number/happy_number_test.go b/problems/happy-number/happy_number_test.go
deleted file mode 100644
index 4428de6d1..000000000
--- a/problems/happy-number/happy_number_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem202
-
-import "testing"
-
-type testType struct {
-	in   int
-	want bool
-}
-
-func TestIsHappy(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   19,
-			want: true,
-		},
-		{
-			in:   1,
-			want: true,
-		},
-		{
-			in:   0,
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isHappy(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/heaters/README.md b/problems/heaters/README.md
deleted file mode 100644
index ffacf380b..000000000
--- a/problems/heaters/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ones-and-zeroes "Ones and Zeroes")
-　　　　　　　　　　　　　　　　
-[Next >](../number-complement "Number Complement")
-
-## [475. Heaters (Medium)](https://leetcode.com/problems/heaters "供暖器")
-
-<p>Winter is coming! During the contest, your first job is to design a standard heater with a fixed warm radius to warm all the houses.</p>
-
-<p>Every house can be warmed, as long as the house is within the heater&#39;s warm radius range.&nbsp;</p>
-
-<p>Given the positions of <code>houses</code> and <code>heaters</code> on a horizontal line, return <em>the minimum radius standard of heaters&nbsp;so that those heaters could cover all houses.</em></p>
-
-<p><strong>Notice</strong> that&nbsp;all the <code>heaters</code> follow your radius standard, and the warm radius will the same.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> houses = [1,2,3], heaters = [2]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only heater was placed in the position 2, and if we use the radius 1 standard, then all the houses can be warmed.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> houses = [1,2,3,4], heaters = [1,4]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The two heater was placed in the position 1 and 4. We need to use radius 1 standard, then all the houses can be warmed.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> houses = [1,5], heaters = [2]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= houses.length, heaters.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= houses[i], heaters[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/heaters/heaters.go b/problems/heaters/heaters.go
deleted file mode 100644
index 0df383b2c..000000000
--- a/problems/heaters/heaters.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem475
diff --git a/problems/heaters/heaters_test.go b/problems/heaters/heaters_test.go
deleted file mode 100644
index 0df383b2c..000000000
--- a/problems/heaters/heaters_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem475
diff --git a/problems/height-checker/README.md b/problems/height-checker/README.md
deleted file mode 100644
index 01ace7bdc..000000000
--- a/problems/height-checker/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../actors-and-directors-who-cooperated-at-least-three-times "Actors and Directors Who Cooperated At Least Three Times")
-　　　　　　　　　　　　　　　　
-[Next >](../grumpy-bookstore-owner "Grumpy Bookstore Owner")
-
-## [1051. Height Checker (Easy)](https://leetcode.com/problems/height-checker "高度检查器")
-
-<p>A school is trying to take an annual photo of all the students. The students are asked to stand in a single file line in <strong>non-decreasing order</strong> by height. Let this ordering be represented by the integer array <code>expected</code> where <code>expected[i]</code> is the expected height of the <code>i<sup>th</sup></code> student in line.</p>
-
-<p>You are given an integer array <code>heights</code> representing the <strong>current order</strong> that the students are standing in. Each <code>heights[i]</code> is the height of the <code>i<sup>th</sup></code> student in line (<strong>0-indexed</strong>).</p>
-
-<p>Return <em>the <strong>number of indices</strong> where </em><code>heights[i] != expected[i]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> heights = [1,1,4,2,1,3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-heights:  [1,1,<u>4</u>,2,<u>1</u>,<u>3</u>]
-expected: [1,1,<u>1</u>,2,<u>3</u>,<u>4</u>]
-Indices 2, 4, and 5 do not match.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> heights = [5,1,2,3,4]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong>
-heights:  [<u>5</u>,<u>1</u>,<u>2</u>,<u>3</u>,<u>4</u>]
-expected: [<u>1</u>,<u>2</u>,<u>3</u>,<u>4</u>,<u>5</u>]
-All indices do not match.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> heights = [1,2,3,4,5]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-heights:  [1,2,3,4,5]
-expected: [1,2,3,4,5]
-All indices match.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= heights.length &lt;= 100</code></li>
-	<li><code>1 &lt;= heights[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Counting Sort](../../tag/counting-sort/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build the correct order of heights by sorting another array, then compare the two arrays.
-</details>
diff --git a/problems/height-checker/height_checker.go b/problems/height-checker/height_checker.go
deleted file mode 100644
index cb595ce4d..000000000
--- a/problems/height-checker/height_checker.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem1051
-
-import "sort"
-
-func heightChecker(heights []int) int {
-	ans, dst := 0, make([]int, len(heights))
-	copy(dst, heights)
-	sort.Ints(dst)
-	for i, v := range dst {
-		if heights[i] != v {
-			ans++
-		}
-	}
-	return ans
-}
diff --git a/problems/height-checker/height_checker_test.go b/problems/height-checker/height_checker_test.go
deleted file mode 100644
index d0461e31f..000000000
--- a/problems/height-checker/height_checker_test.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem1051
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestHeightChecker(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 1, 4, 2, 1, 3},
-			want: 3,
-		},
-	}
-	for _, tt := range tests {
-		got := heightChecker(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/hexspeak/README.md b/problems/hexspeak/README.md
deleted file mode 100644
index a1b971d22..000000000
--- a/problems/hexspeak/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-people-report-to-the-given-manager "All People Report to the Given Manager")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-interval "Remove Interval")
-
-## [1271. Hexspeak (Easy)](https://leetcode.com/problems/hexspeak "十六进制魔术数字")
-
-<p>A decimal number can be converted to its&nbsp;<em>Hexspeak representation</em>&nbsp;by first converting it to an uppercase hexadecimal string, then replacing all occurrences of the digit <code>0</code> with the letter <code>O</code>, and the digit <code>1</code> with the letter <code>I</code>.&nbsp; Such a representation&nbsp;is <em>valid</em>&nbsp;if and only if it consists only of the letters in the set <code>{&quot;A&quot;, &quot;B&quot;, &quot;C&quot;, &quot;D&quot;, &quot;E&quot;, &quot;F&quot;, &quot;I&quot;, &quot;O&quot;}</code>.</p>
-
-<p>Given a string <code>num</code>&nbsp;representing a decimal integer <code>N</code>, return the Hexspeak representation of <code>N</code> if it is valid, otherwise return <code>&quot;ERROR&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;257&quot;
-<strong>Output:</strong> &quot;IOI&quot;
-<b>Explanation: </b> 257 is 101 in hexadecimal.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;3&quot;
-<strong>Output:</strong> &quot;ERROR&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= N &lt;= 10^12</code></li>
-	<li>There are no leading zeros in the given string.</li>
-	<li>All answers must be in uppercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert the given number to hexadecimal.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Replace all 0 and 1 with 'O' and 'I'.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Check if the final string has any numerical digits.
-</details>
diff --git a/problems/hexspeak/hexspeak.go b/problems/hexspeak/hexspeak.go
deleted file mode 100644
index 9f81f7d0d..000000000
--- a/problems/hexspeak/hexspeak.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem1271
-
-import (
-	"fmt"
-	"strconv"
-	"strings"
-)
-
-func toHexspeak(num string) string {
-	n, _ := strconv.Atoi(num)
-	hex := fmt.Sprintf("%X", n)
-	hex = strings.NewReplacer("0", "O", "1", "I").Replace(hex)
-	for _, v := range hex {
-		if v < 'A' {
-			return "ERROR"
-		}
-	}
-	return hex
-}
diff --git a/problems/hexspeak/hexspeak_test.go b/problems/hexspeak/hexspeak_test.go
deleted file mode 100644
index 07bf6f44c..000000000
--- a/problems/hexspeak/hexspeak_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem1271
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestToHexspeak(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "257",
-			want: "IOI",
-		},
-		{
-			in:   "3",
-			want: "ERROR",
-		},
-	}
-	for _, tt := range tests {
-		got := toHexspeak(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/high-five/README.md b/problems/high-five/README.md
deleted file mode 100644
index 87d79b579..000000000
--- a/problems/high-five/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-digits-in-the-minimum-number "Sum of Digits in the Minimum Number")
-　　　　　　　　　　　　　　　　
-[Next >](../brace-expansion "Brace Expansion")
-
-## [1086. High Five (Easy)](https://leetcode.com/problems/high-five "前五科的均分")
-
-<p>Given a list of scores of different students, return the average score of each student&#39;s <strong>top five scores</strong> in<strong> the order of each student&#39;s id</strong>.</p>
-
-<p>Each entry <code>items[i]</code>&nbsp;has <code>items[i][0]</code> the student&#39;s id, and <code>items[i][1]</code> the student&#39;s score.&nbsp; The average score is calculated using integer division.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[[1,91],[1,92],[2,93],[2,97],[1,60],[2,77],[1,65],[1,87],[1,100],[2,100],[2,76]]</span>
-<strong>Output: </strong><span id="example-output-1">[[1,87],[2,88]]</span>
-<strong>Explanation: </strong>
-The average of the student with id = 1 is 87.
-The average of the student with id = 2 is 88.6. But with integer division their average converts to 88.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= items.length &lt;= 1000</code></li>
-	<li><code>items[i].length == 2</code></li>
-	<li>The IDs of the students is between <code>1</code> to <code>1000</code></li>
-	<li>The score of the students is between <code>1</code> to <code>100</code></li>
-	<li>For each student,&nbsp;there are at least 5 scores</li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can we solve the problem if we have just one student?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Given an student sort their grades and get the top 5 average.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Generalize the idea to do it for many students.
-</details>
diff --git a/problems/highest-grade-for-each-student/README.md b/problems/highest-grade-for-each-student/README.md
deleted file mode 100644
index 42134a56f..000000000
--- a/problems/highest-grade-for-each-student/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-nesting-depth-of-two-valid-parentheses-strings "Maximum Nesting Depth of Two Valid Parentheses Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../reported-posts "Reported Posts")
-
-## [1112. Highest Grade For Each Student (Medium)](https://leetcode.com/problems/highest-grade-for-each-student "每位学生的最高成绩")
-
-<p>Table: <code>Enrollments</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| student_id    | int     |
-| course_id     | int     |
-| grade         | int     |
-+---------------+---------+
-(student_id, course_id) is the primary key of this table.
-
-</pre>
-
-<p>Write a SQL query to find the highest grade with its corresponding course for each student. In case of a tie, you should find the course with the smallest&nbsp;<code>course_id</code>. The output must be sorted by increasing <code>student_id</code>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Enrollments table:
-+------------+-------------------+
-| student_id | course_id | grade |
-+------------+-----------+-------+
-| 2          | 2         | 95    |
-| 2          | 3         | 95    |
-| 1          | 1         | 90    |
-| 1          | 2         | 99    |
-| 3          | 1         | 80    |
-| 3          | 2         | 75    |
-| 3          | 3         | 82    |
-+------------+-----------+-------+
-
-Result table:
-+------------+-------------------+
-| student_id | course_id | grade |
-+------------+-----------+-------+
-| 1          | 2         | 99    |
-| 2          | 2         | 95    |
-| 3          | 3         | 82    |
-+------------+-----------+-------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/highest-grade-for-each-student/highest_grade_for_each_student.sql b/problems/highest-grade-for-each-student/highest_grade_for_each_student.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/highest-grade-for-each-student/highest_grade_for_each_student.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/highest-grade-for-each-student/mysql_schemas.sql b/problems/highest-grade-for-each-student/mysql_schemas.sql
deleted file mode 100644
index 8d245e074..000000000
--- a/problems/highest-grade-for-each-student/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Enrollments (student_id int, course_id int, grade int);
-Truncate table Enrollments;
-insert into Enrollments (student_id, course_id, grade) values ('2', '2', '95');
-insert into Enrollments (student_id, course_id, grade) values ('2', '3', '95');
-insert into Enrollments (student_id, course_id, grade) values ('1', '1', '90');
-insert into Enrollments (student_id, course_id, grade) values ('1', '2', '99');
-insert into Enrollments (student_id, course_id, grade) values ('3', '1', '80');
-insert into Enrollments (student_id, course_id, grade) values ('3', '2', '75');
-insert into Enrollments (student_id, course_id, grade) values ('3', '3', '82');
diff --git a/problems/hopper-company-queries-i/README.md b/problems/hopper-company-queries-i/README.md
deleted file mode 100644
index c436e61f3..000000000
--- a/problems/hopper-company-queries-i/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-two-polynomials-represented-as-linked-lists "Add Two Polynomials Represented as Linked Lists")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-array-by-increasing-frequency "Sort Array by Increasing Frequency")
-
-## [1635. Hopper Company Queries I (Hard)](https://leetcode.com/problems/hopper-company-queries-i "Hopper 公司查询 I")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/hopper-company-queries-i/mysql_schemas.sql b/problems/hopper-company-queries-i/mysql_schemas.sql
deleted file mode 100644
index f66daff0b..000000000
--- a/problems/hopper-company-queries-i/mysql_schemas.sql
+++ /dev/null
@@ -1,39 +0,0 @@
-Create table If Not Exists Drivers (driver_id int, join_date date);
-Create table If Not Exists Rides (ride_id int, user_id int, requested_at date);
-Create table If Not Exists AcceptedRides (ride_id int, driver_id int, ride_distance int, ride_duration int);
-Truncate table Drivers;
-insert into Drivers (driver_id, join_date) values ('10', '2019-12-10');
-insert into Drivers (driver_id, join_date) values ('8', '2020-1-13');
-insert into Drivers (driver_id, join_date) values ('5', '2020-2-16');
-insert into Drivers (driver_id, join_date) values ('7', '2020-3-8');
-insert into Drivers (driver_id, join_date) values ('4', '2020-5-17');
-insert into Drivers (driver_id, join_date) values ('1', '2020-10-24');
-insert into Drivers (driver_id, join_date) values ('6', '2021-1-5');
-Truncate table Rides;
-insert into Rides (ride_id, user_id, requested_at) values ('6', '75', '2019-12-9');
-insert into Rides (ride_id, user_id, requested_at) values ('1', '54', '2020-2-9');
-insert into Rides (ride_id, user_id, requested_at) values ('10', '63', '2020-3-4');
-insert into Rides (ride_id, user_id, requested_at) values ('19', '39', '2020-4-6');
-insert into Rides (ride_id, user_id, requested_at) values ('3', '41', '2020-6-3');
-insert into Rides (ride_id, user_id, requested_at) values ('13', '52', '2020-6-22');
-insert into Rides (ride_id, user_id, requested_at) values ('7', '69', '2020-7-16');
-insert into Rides (ride_id, user_id, requested_at) values ('17', '70', '2020-8-25');
-insert into Rides (ride_id, user_id, requested_at) values ('20', '81', '2020-11-2');
-insert into Rides (ride_id, user_id, requested_at) values ('5', '57', '2020-11-9');
-insert into Rides (ride_id, user_id, requested_at) values ('2', '42', '2020-12-9');
-insert into Rides (ride_id, user_id, requested_at) values ('11', '68', '2021-1-11');
-insert into Rides (ride_id, user_id, requested_at) values ('15', '32', '2021-1-17');
-insert into Rides (ride_id, user_id, requested_at) values ('12', '11', '2021-1-19');
-insert into Rides (ride_id, user_id, requested_at) values ('14', '18', '2021-1-27');
-Truncate table AcceptedRides;
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('10', '10', '63', '38');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('13', '10', '73', '96');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('7', '8', '100', '28');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('17', '7', '119', '68');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('20', '1', '121', '92');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('5', '7', '42', '101');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('2', '4', '6', '38');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('11', '8', '37', '43');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('15', '8', '108', '82');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('12', '8', '38', '34');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('14', '1', '90', '74');
diff --git a/problems/hopper-company-queries-ii/README.md b/problems/hopper-company-queries-ii/README.md
deleted file mode 100644
index 61349c63d..000000000
--- a/problems/hopper-company-queries-ii/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lowest-common-ancestor-of-a-binary-tree-ii "Lowest Common Ancestor of a Binary Tree II")
-　　　　　　　　　　　　　　　　
-[Next >](../get-maximum-in-generated-array "Get Maximum in Generated Array")
-
-## [1645. Hopper Company Queries II (Hard)](https://leetcode.com/problems/hopper-company-queries-ii "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/hopper-company-queries-ii/mysql_schemas.sql b/problems/hopper-company-queries-ii/mysql_schemas.sql
deleted file mode 100644
index f66daff0b..000000000
--- a/problems/hopper-company-queries-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,39 +0,0 @@
-Create table If Not Exists Drivers (driver_id int, join_date date);
-Create table If Not Exists Rides (ride_id int, user_id int, requested_at date);
-Create table If Not Exists AcceptedRides (ride_id int, driver_id int, ride_distance int, ride_duration int);
-Truncate table Drivers;
-insert into Drivers (driver_id, join_date) values ('10', '2019-12-10');
-insert into Drivers (driver_id, join_date) values ('8', '2020-1-13');
-insert into Drivers (driver_id, join_date) values ('5', '2020-2-16');
-insert into Drivers (driver_id, join_date) values ('7', '2020-3-8');
-insert into Drivers (driver_id, join_date) values ('4', '2020-5-17');
-insert into Drivers (driver_id, join_date) values ('1', '2020-10-24');
-insert into Drivers (driver_id, join_date) values ('6', '2021-1-5');
-Truncate table Rides;
-insert into Rides (ride_id, user_id, requested_at) values ('6', '75', '2019-12-9');
-insert into Rides (ride_id, user_id, requested_at) values ('1', '54', '2020-2-9');
-insert into Rides (ride_id, user_id, requested_at) values ('10', '63', '2020-3-4');
-insert into Rides (ride_id, user_id, requested_at) values ('19', '39', '2020-4-6');
-insert into Rides (ride_id, user_id, requested_at) values ('3', '41', '2020-6-3');
-insert into Rides (ride_id, user_id, requested_at) values ('13', '52', '2020-6-22');
-insert into Rides (ride_id, user_id, requested_at) values ('7', '69', '2020-7-16');
-insert into Rides (ride_id, user_id, requested_at) values ('17', '70', '2020-8-25');
-insert into Rides (ride_id, user_id, requested_at) values ('20', '81', '2020-11-2');
-insert into Rides (ride_id, user_id, requested_at) values ('5', '57', '2020-11-9');
-insert into Rides (ride_id, user_id, requested_at) values ('2', '42', '2020-12-9');
-insert into Rides (ride_id, user_id, requested_at) values ('11', '68', '2021-1-11');
-insert into Rides (ride_id, user_id, requested_at) values ('15', '32', '2021-1-17');
-insert into Rides (ride_id, user_id, requested_at) values ('12', '11', '2021-1-19');
-insert into Rides (ride_id, user_id, requested_at) values ('14', '18', '2021-1-27');
-Truncate table AcceptedRides;
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('10', '10', '63', '38');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('13', '10', '73', '96');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('7', '8', '100', '28');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('17', '7', '119', '68');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('20', '1', '121', '92');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('5', '7', '42', '101');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('2', '4', '6', '38');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('11', '8', '37', '43');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('15', '8', '108', '82');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('12', '8', '38', '34');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('14', '1', '90', '74');
diff --git a/problems/hopper-company-queries-iii/README.md b/problems/hopper-company-queries-iii/README.md
deleted file mode 100644
index 5424cf7fb..000000000
--- a/problems/hopper-company-queries-iii/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lowest-common-ancestor-of-a-binary-tree-iii "Lowest Common Ancestor of a Binary Tree III")
-　　　　　　　　　　　　　　　　
-[Next >](../defuse-the-bomb "Defuse the Bomb")
-
-## [1651. Hopper Company Queries III (Hard)](https://leetcode.com/problems/hopper-company-queries-iii "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/hopper-company-queries-iii/mysql_schemas.sql b/problems/hopper-company-queries-iii/mysql_schemas.sql
deleted file mode 100644
index f66daff0b..000000000
--- a/problems/hopper-company-queries-iii/mysql_schemas.sql
+++ /dev/null
@@ -1,39 +0,0 @@
-Create table If Not Exists Drivers (driver_id int, join_date date);
-Create table If Not Exists Rides (ride_id int, user_id int, requested_at date);
-Create table If Not Exists AcceptedRides (ride_id int, driver_id int, ride_distance int, ride_duration int);
-Truncate table Drivers;
-insert into Drivers (driver_id, join_date) values ('10', '2019-12-10');
-insert into Drivers (driver_id, join_date) values ('8', '2020-1-13');
-insert into Drivers (driver_id, join_date) values ('5', '2020-2-16');
-insert into Drivers (driver_id, join_date) values ('7', '2020-3-8');
-insert into Drivers (driver_id, join_date) values ('4', '2020-5-17');
-insert into Drivers (driver_id, join_date) values ('1', '2020-10-24');
-insert into Drivers (driver_id, join_date) values ('6', '2021-1-5');
-Truncate table Rides;
-insert into Rides (ride_id, user_id, requested_at) values ('6', '75', '2019-12-9');
-insert into Rides (ride_id, user_id, requested_at) values ('1', '54', '2020-2-9');
-insert into Rides (ride_id, user_id, requested_at) values ('10', '63', '2020-3-4');
-insert into Rides (ride_id, user_id, requested_at) values ('19', '39', '2020-4-6');
-insert into Rides (ride_id, user_id, requested_at) values ('3', '41', '2020-6-3');
-insert into Rides (ride_id, user_id, requested_at) values ('13', '52', '2020-6-22');
-insert into Rides (ride_id, user_id, requested_at) values ('7', '69', '2020-7-16');
-insert into Rides (ride_id, user_id, requested_at) values ('17', '70', '2020-8-25');
-insert into Rides (ride_id, user_id, requested_at) values ('20', '81', '2020-11-2');
-insert into Rides (ride_id, user_id, requested_at) values ('5', '57', '2020-11-9');
-insert into Rides (ride_id, user_id, requested_at) values ('2', '42', '2020-12-9');
-insert into Rides (ride_id, user_id, requested_at) values ('11', '68', '2021-1-11');
-insert into Rides (ride_id, user_id, requested_at) values ('15', '32', '2021-1-17');
-insert into Rides (ride_id, user_id, requested_at) values ('12', '11', '2021-1-19');
-insert into Rides (ride_id, user_id, requested_at) values ('14', '18', '2021-1-27');
-Truncate table AcceptedRides;
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('10', '10', '63', '38');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('13', '10', '73', '96');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('7', '8', '100', '28');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('17', '7', '119', '68');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('20', '1', '121', '92');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('5', '7', '42', '101');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('2', '4', '6', '38');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('11', '8', '37', '43');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('15', '8', '108', '82');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('12', '8', '38', '34');
-insert into AcceptedRides (ride_id, driver_id, ride_distance, ride_duration) values ('14', '1', '90', '74');
diff --git a/problems/house-robber-ii/README.md b/problems/house-robber-ii/README.md
deleted file mode 100644
index 221ff0d5e..000000000
--- a/problems/house-robber-ii/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-search-ii "Word Search II")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-palindrome "Shortest Palindrome")
-
-## [213. House Robber II (Medium)](https://leetcode.com/problems/house-robber-ii "打家劫舍 II")
-
-<p>You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are <strong>arranged in a circle.</strong> That means the first house is the neighbor of the last one. Meanwhile, adjacent houses have a security system connected, and&nbsp;<b>it will automatically contact the police if two adjacent houses were broken into on the same night</b>.</p>
-
-<p>Given an integer array <code>nums</code> representing the amount of money of each house, return <em>the maximum amount of money you can rob tonight <strong>without alerting the police</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You cannot rob house 1 (money = 2) and then rob house 3 (money = 2), because they are adjacent houses.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,1]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Rob house 1 (money = 1) and then rob house 3 (money = 3).
-Total amount you can rob = 1 + 3 = 4.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [House Robber](../house-robber) (Medium)
-  1. [Paint House](../paint-house) (Medium)
-  1. [Paint Fence](../paint-fence) (Medium)
-  1. [House Robber III](../house-robber-iii) (Medium)
-  1. [Non-negative Integers without Consecutive Ones](../non-negative-integers-without-consecutive-ones) (Hard)
-  1. [Coin Path](../coin-path) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since House[1] and House[n] are adjacent, they cannot be robbed together. Therefore, the problem becomes to rob either House[1]-House[n-1] or House[2]-House[n], depending on which choice offers more money. Now the problem has degenerated to the <a href ="https://leetcode.com/problems/house-robber/description/">House Robber</a>, which is already been solved.
-</details>
diff --git a/problems/house-robber-ii/house_robber_ii.go b/problems/house-robber-ii/house_robber_ii.go
deleted file mode 100644
index 402d98950..000000000
--- a/problems/house-robber-ii/house_robber_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem213
diff --git a/problems/house-robber-ii/house_robber_ii_test.go b/problems/house-robber-ii/house_robber_ii_test.go
deleted file mode 100644
index 402d98950..000000000
--- a/problems/house-robber-ii/house_robber_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem213
diff --git a/problems/house-robber-iii/README.md b/problems/house-robber-iii/README.md
deleted file mode 100644
index 350409147..000000000
--- a/problems/house-robber-iii/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-pairs "Palindrome Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../counting-bits "Counting Bits")
-
-## [337. House Robber III (Medium)](https://leetcode.com/problems/house-robber-iii "打家劫舍 III")
-
-<p>The thief has found himself a new place for his thievery again. There is only one entrance to this area, called <code>root</code>.</p>
-
-<p>Besides the <code>root</code>, each house has one and only one parent house. After a tour, the smart thief realized that all houses in this place form a binary tree. It will automatically contact the police if <strong>two directly-linked houses were broken into on the same night</strong>.</p>
-
-<p>Given the <code>root</code> of the binary tree, return <em>the maximum amount of money the thief can rob <strong>without alerting the police</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/10/rob1-tree.jpg" style="width: 277px; height: 293px;" />
-<pre>
-<strong>Input:</strong> root = [3,2,3,null,3,null,1]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> Maximum amount of money the thief can rob = 3 + 3 + 1 = 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/10/rob2-tree.jpg" style="width: 357px; height: 293px;" />
-<pre>
-<strong>Input:</strong> root = [3,4,5,1,3,null,1]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> Maximum amount of money the thief can rob = 4 + 5 = 9.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [House Robber](../house-robber) (Medium)
-  1. [House Robber II](../house-robber-ii) (Medium)
diff --git a/problems/house-robber-iii/house_robber_iii.go b/problems/house-robber-iii/house_robber_iii.go
deleted file mode 100644
index fed711a9a..000000000
--- a/problems/house-robber-iii/house_robber_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem337
diff --git a/problems/house-robber-iii/house_robber_iii_test.go b/problems/house-robber-iii/house_robber_iii_test.go
deleted file mode 100644
index fed711a9a..000000000
--- a/problems/house-robber-iii/house_robber_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem337
diff --git a/problems/house-robber/README.md b/problems/house-robber/README.md
deleted file mode 100644
index a37cd0a07..000000000
--- a/problems/house-robber/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rising-temperature "Rising Temperature")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-right-side-view "Binary Tree Right Side View")
-
-## [198. House Robber (Medium)](https://leetcode.com/problems/house-robber "打家劫舍")
-
-<p>You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security systems connected and <b>it will automatically contact the police if two adjacent houses were broken into on the same night</b>.</p>
-
-<p>Given an integer array <code>nums</code> representing the amount of money of each house, return <em>the maximum amount of money you can rob tonight <b>without alerting the police</b></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,1]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Rob house 1 (money = 1) and then rob house 3 (money = 3).
-Total amount you can rob = 1 + 3 = 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,7,9,3,1]
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> Rob house 1 (money = 2), rob house 3 (money = 9) and rob house 5 (money = 1).
-Total amount you can rob = 2 + 9 + 1 = 12.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 400</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Maximum Product Subarray](../maximum-product-subarray) (Medium)
-  1. [House Robber II](../house-robber-ii) (Medium)
-  1. [Paint House](../paint-house) (Medium)
-  1. [Paint Fence](../paint-fence) (Medium)
-  1. [House Robber III](../house-robber-iii) (Medium)
-  1. [Non-negative Integers without Consecutive Ones](../non-negative-integers-without-consecutive-ones) (Hard)
-  1. [Coin Path](../coin-path) (Hard)
-  1. [Delete and Earn](../delete-and-earn) (Medium)
diff --git a/problems/house-robber/house_robber.go b/problems/house-robber/house_robber.go
deleted file mode 100644
index a1da7be55..000000000
--- a/problems/house-robber/house_robber.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem198
-
-func rob(nums []int) int {
-	pre1, pre2, ans := 0, 0, 0
-	for _, v := range nums {
-		if ans = pre1 + v; pre2 > ans {
-			ans = pre2
-		}
-		pre1, pre2 = pre2, ans
-	}
-	return ans
-}
diff --git a/problems/house-robber/house_robber_test.go b/problems/house-robber/house_robber_test.go
deleted file mode 100644
index 680d832b9..000000000
--- a/problems/house-robber/house_robber_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem198
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestRob(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3, 1},
-			want: 4,
-		},
-		{
-			in:   []int{2, 7, 9, 3, 1},
-			want: 12,
-		},
-	}
-	for _, tt := range tests {
-		got := rob(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/how-many-apples-can-you-put-into-the-basket/README.md b/problems/how-many-apples-can-you-put-into-the-basket/README.md
deleted file mode 100644
index b933f4598..000000000
--- a/problems/how-many-apples-can-you-put-into-the-basket/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fizz-buzz-multithreaded "Fizz Buzz Multithreaded")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-knight-moves "Minimum Knight Moves")
-
-## [1196. How Many Apples Can You Put into the Basket (Easy)](https://leetcode.com/problems/how-many-apples-can-you-put-into-the-basket "最多可以买到的苹果数量")
-
-<p>You have some apples, where <code>arr[i]</code> is the weight of the <code>i</code>-th apple.&nbsp; You also have a basket that can carry up to <code>5000</code> units of weight.</p>
-
-<p>Return the maximum number of apples you can put in the basket.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [100,200,150,1000]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>All 4 apples can be carried by the basket since their sum of weights is 1450.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [900,950,800,1000,700,800]
-<strong>Output:</strong> 5
-<strong>Explanation: </strong>The sum of weights of the 6 apples exceeds 5000 so we choose any 5 of them.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10^3</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10^3</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if you think in a greedy approach?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The best apple to take in one step is the one with the smallest weight.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Sort the array and take apples with smaller weight first.
-</details>
diff --git a/problems/how-many-numbers-are-smaller-than-the-current-number/README.md b/problems/how-many-numbers-are-smaller-than-the-current-number/README.md
deleted file mode 100644
index 2b291471d..000000000
--- a/problems/how-many-numbers-are-smaller-than-the-current-number/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-trusted-contacts-of-a-customer "Number of Trusted Contacts of a Customer")
-　　　　　　　　　　　　　　　　
-[Next >](../rank-teams-by-votes "Rank Teams by Votes")
-
-## [1365. How Many Numbers Are Smaller Than the Current Number (Easy)](https://leetcode.com/problems/how-many-numbers-are-smaller-than-the-current-number "有多少小于当前数字的数字")
-
-<p>Given the array <code>nums</code>, for each <code>nums[i]</code> find out how many numbers in the array are smaller than it. That is, for each <code>nums[i]</code> you have to count the number of valid <code>j&#39;s</code>&nbsp;such that&nbsp;<code>j != i</code> <strong>and</strong> <code>nums[j] &lt; nums[i]</code>.</p>
-
-<p>Return the answer in an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [8,1,2,2,3]
-<strong>Output:</strong> [4,0,1,1,3]
-<strong>Explanation:</strong> 
-For nums[0]=8 there exist four smaller numbers than it (1, 2, 2 and 3). 
-For nums[1]=1 does not exist any smaller number than it.
-For nums[2]=2 there exist one smaller number than it (1). 
-For nums[3]=2 there exist one smaller number than it (1). 
-For nums[4]=3 there exist three smaller numbers than it (1, 2 and 2).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [6,5,4,8]
-<strong>Output:</strong> [2,1,0,3]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,7,7,7]
-<strong>Output:</strong> [0,0,0,0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 500</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Count of Smaller Numbers After Self](../count-of-smaller-numbers-after-self) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Brute force for each array element.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In order to improve the time complexity, we can sort the array and get the answer for each array element.
-</details>
diff --git a/problems/html-entity-parser/README.md b/problems/html-entity-parser/README.md
deleted file mode 100644
index 5201de90f..000000000
--- a/problems/html-entity-parser/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../queries-on-a-permutation-with-key "Queries on a Permutation With Key")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-paint-n-3-grid "Number of Ways to Paint N × 3 Grid")
-
-## [1410. HTML Entity Parser (Medium)](https://leetcode.com/problems/html-entity-parser "HTML 实体解析器")
-
-<p><strong>HTML entity parser</strong> is the parser that takes HTML code as input and replace all the entities of the special characters by the characters itself.</p>
-
-<p>The special characters and their entities for HTML are:</p>
-
-<ul>
-	<li><strong>Quotation Mark:</strong> the entity is <code>&amp;quot;</code> and symbol character is <code>&quot;</code>.</li>
-	<li><strong>Single Quote Mark:</strong> the entity is <code>&amp;apos;</code> and symbol character is <code>&#39;</code>.</li>
-	<li><strong>Ampersand:</strong> the entity is <code>&amp;amp;</code> and symbol character is <code>&amp;</code>.</li>
-	<li><strong>Greater Than Sign:</strong> the entity is <code>&amp;gt;</code> and symbol character is <code>&gt;</code>.</li>
-	<li><strong>Less Than Sign:</strong> the entity is <code>&amp;lt;</code> and symbol character is <code>&lt;</code>.</li>
-	<li><strong>Slash:</strong> the entity is <code>&amp;frasl;</code> and symbol character is <code>/</code>.</li>
-</ul>
-
-<p>Given the input <code>text</code> string to the HTML parser, you have to implement the entity parser.</p>
-
-<p>Return <em>the text after replacing the entities by the special characters</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;&amp;amp; is an HTML entity but &amp;ambassador; is not.&quot;
-<strong>Output:</strong> &quot;&amp; is an HTML entity but &amp;ambassador; is not.&quot;
-<strong>Explanation:</strong> The parser will replace the &amp;amp; entity by &amp;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;and I quote: &amp;quot;...&amp;quot;&quot;
-<strong>Output:</strong> &quot;and I quote: \&quot;...\&quot;&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= text.length &lt;= 10<sup>5</sup></code></li>
-	<li>The string may contain any possible characters out of all the 256 ASCII characters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Search the string for all the occurrences of the character '&'.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For every '&' check if it matches an HTML entity by checking the ';' character and if entity found replace it in the answer.
-</details>
diff --git a/problems/human-traffic-of-stadium/README.md b/problems/human-traffic-of-stadium/README.md
deleted file mode 100644
index ffdab638f..000000000
--- a/problems/human-traffic-of-stadium/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../non-negative-integers-without-consecutive-ones "Non-negative Integers without Consecutive Ones")
-　　　　　　　　　　　　　　　　
-[Next >](../friend-requests-ii-who-has-the-most-friends "Friend Requests II: Who Has the Most Friends")
-
-## [601. Human Traffic of Stadium (Hard)](https://leetcode.com/problems/human-traffic-of-stadium "体育馆的人流量")
-
-<p>Table: <code>Stadium</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| visit_date    | date    |
-| people        | int     |
-+---------------+---------+
-visit_date is the primary key for this table.
-Each row of this table contains the visit date and visit id to the stadium with the number of people during the visit.
-No two rows will have the same visit_date, and as the id increases, the dates increase as well.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to display the records with three or more rows with <strong>consecutive</strong> <code>id</code>&#39;s, and the number of people is greater than or equal to 100 for each.</p>
-
-<p>Return the result table ordered by <code>visit_date</code> in <strong>ascending order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Stadium table:
-+------+------------+-----------+
-| id   | visit_date | people    |
-+------+------------+-----------+
-| 1    | 2017-01-01 | 10        |
-| 2    | 2017-01-02 | 109       |
-| 3    | 2017-01-03 | 150       |
-| 4    | 2017-01-04 | 99        |
-| 5    | 2017-01-05 | 145       |
-| 6    | 2017-01-06 | 1455      |
-| 7    | 2017-01-07 | 199       |
-| 8    | 2017-01-09 | 188       |
-+------+------------+-----------+
-<strong>Output:</strong> 
-+------+------------+-----------+
-| id   | visit_date | people    |
-+------+------------+-----------+
-| 5    | 2017-01-05 | 145       |
-| 6    | 2017-01-06 | 1455      |
-| 7    | 2017-01-07 | 199       |
-| 8    | 2017-01-09 | 188       |
-+------+------------+-----------+
-<strong>Explanation:</strong> 
-The four rows with ids 5, 6, 7, and 8 have consecutive ids and each of them has &gt;= 100 people attended. Note that row 8 was included even though the visit_date was not the next day after row 7.
-The rows with ids 2 and 3 are not included because we need at least three consecutive ids.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/human-traffic-of-stadium/human_traffic_of_stadium.sql b/problems/human-traffic-of-stadium/human_traffic_of_stadium.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/human-traffic-of-stadium/human_traffic_of_stadium.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/human-traffic-of-stadium/mysql_schemas.sql b/problems/human-traffic-of-stadium/mysql_schemas.sql
deleted file mode 100644
index b01b95410..000000000
--- a/problems/human-traffic-of-stadium/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Stadium (id int, visit_date DATE NULL, people int);
-Truncate table Stadium;
-insert into Stadium (id, visit_date, people) values ('1', '2017-01-01', '10');
-insert into Stadium (id, visit_date, people) values ('2', '2017-01-02', '109');
-insert into Stadium (id, visit_date, people) values ('3', '2017-01-03', '150');
-insert into Stadium (id, visit_date, people) values ('4', '2017-01-04', '99');
-insert into Stadium (id, visit_date, people) values ('5', '2017-01-05', '145');
-insert into Stadium (id, visit_date, people) values ('6', '2017-01-06', '1455');
-insert into Stadium (id, visit_date, people) values ('7', '2017-01-07', '199');
-insert into Stadium (id, visit_date, people) values ('8', '2017-01-09', '188');
diff --git a/problems/image-overlap/README.md b/problems/image-overlap/README.md
deleted file mode 100644
index 808a96906..000000000
--- a/problems/image-overlap/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-distances-in-tree "Sum of Distances in Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../rectangle-overlap "Rectangle Overlap")
-
-## [835. Image Overlap (Medium)](https://leetcode.com/problems/image-overlap "图像重叠")
-
-<p>You are given two images, <code>img1</code> and <code>img2</code>, represented as binary, square matrices of size <code>n x n</code>. A binary matrix has only <code>0</code>s and <code>1</code>s as values.</p>
-
-<p>We <strong>translate</strong> one image however we choose by sliding all the <code>1</code> bits left, right, up, and/or down any number of units. We then place it on top of the other image. We can then calculate the <strong>overlap</strong> by counting the number of positions that have a <code>1</code> in <strong>both</strong> images.</p>
-
-<p>Note also that a translation does <strong>not</strong> include any kind of rotation. Any <code>1</code> bits that are translated outside of the matrix borders are erased.</p>
-
-<p>Return <em>the largest possible overlap</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/09/overlap1.jpg" style="width: 450px; height: 231px;" />
-<pre>
-<strong>Input:</strong> img1 = [[1,1,0],[0,1,0],[0,1,0]], img2 = [[0,0,0],[0,1,1],[0,0,1]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We translate img1 to right by 1 unit and down by 1 unit.
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/09/overlap_step1.jpg" style="width: 450px; height: 105px;" />
-The number of positions that have a 1 in both images is 3 (shown in red).
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/09/overlap_step2.jpg" style="width: 450px; height: 231px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> img1 = [[1]], img2 = [[1]]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> img1 = [[0]], img2 = [[0]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == img1.length == img1[i].length</code></li>
-	<li><code>n == img2.length == img2[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 30</code></li>
-	<li><code>img1[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-	<li><code>img2[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/image-overlap/image_overlap.go b/problems/image-overlap/image_overlap.go
deleted file mode 100644
index 5f37d5c04..000000000
--- a/problems/image-overlap/image_overlap.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem835
diff --git a/problems/image-overlap/image_overlap_test.go b/problems/image-overlap/image_overlap_test.go
deleted file mode 100644
index 5f37d5c04..000000000
--- a/problems/image-overlap/image_overlap_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem835
diff --git a/problems/image-smoother/README.md b/problems/image-smoother/README.md
deleted file mode 100644
index 357df58ca..000000000
--- a/problems/image-smoother/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-9 "Remove 9")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-width-of-binary-tree "Maximum Width of Binary Tree")
-
-## [661. Image Smoother (Easy)](https://leetcode.com/problems/image-smoother "图片平滑器")
-
-<p>An <strong>image smoother</strong> is a filter of the size <code>3 x 3</code> that can be applied to each cell of an image by rounding down the average of the cell and the eight surrounding cells (i.e., the average of the nine cells in the blue smoother). If one or more of the surrounding cells of a cell is not present, we do not consider it in the average (i.e., the average of the four cells in the red smoother).</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/smoother-grid.jpg" style="width: 493px; height: 493px;" />
-<p>Given an <code>m x n</code> integer matrix <code>img</code> representing the grayscale of an image, return <em>the image after applying the smoother on each cell of it</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/smooth-grid.jpg" style="width: 613px; height: 253px;" />
-<pre>
-<strong>Input:</strong> img = [[1,1,1],[1,0,1],[1,1,1]]
-<strong>Output:</strong> [[0,0,0],[0,0,0],[0,0,0]]
-<strong>Explanation:</strong>
-For the points (0,0), (0,2), (2,0), (2,2): floor(3/4) = floor(0.75) = 0
-For the points (0,1), (1,0), (1,2), (2,1): floor(5/6) = floor(0.83333333) = 0
-For the point (1,1): floor(8/9) = floor(0.88888889) = 0
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/smooth2-grid.jpg" style="width: 613px; height: 253px;" />
-<pre>
-<strong>Input:</strong> img = [[100,200,100],[200,50,200],[100,200,100]]
-<strong>Output:</strong> [[137,141,137],[141,138,141],[137,141,137]]
-<strong>Explanation:</strong>
-For the points (0,0), (0,2), (2,0), (2,2): floor((100+200+200+50)/4) = floor(137.5) = 137
-For the points (0,1), (1,0), (1,2), (2,1): floor((200+200+50+200+100+100)/6) = floor(141.666667) = 141
-For the point (1,1): floor((50+200+200+200+200+100+100+100+100)/9) = floor(138.888889) = 138
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == img.length</code></li>
-	<li><code>n == img[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>0 &lt;= img[i][j] &lt;= 255</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/image-smoother/image_smoother.go b/problems/image-smoother/image_smoother.go
deleted file mode 100644
index b5b1846d5..000000000
--- a/problems/image-smoother/image_smoother.go
+++ /dev/null
@@ -1,22 +0,0 @@
-package problem661
-
-func imageSmoother(M [][]int) [][]int {
-	r, c := len(M), len(M[0])
-	ans := make([][]int, r)
-	for i := 0; i < r; i++ {
-		ans[i] = make([]int, c)
-		for j := 0; j < c; j++ {
-			sum, count := 0, 0
-			for m := i - 1; m <= i+1; m++ {
-				for n := j - 1; n <= j+1; n++ {
-					if m >= 0 && n >= 0 && m < r && n < c {
-						sum += M[m][n]
-						count++
-					}
-				}
-			}
-			ans[i][j] = sum / count
-		}
-	}
-	return ans
-}
diff --git a/problems/image-smoother/image_smoother_test.go b/problems/image-smoother/image_smoother_test.go
deleted file mode 100644
index af0f48502..000000000
--- a/problems/image-smoother/image_smoother_test.go
+++ /dev/null
@@ -1,46 +0,0 @@
-package problem661
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   [][]int
-	want [][]int
-}
-
-func TestImageSmoother(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{1, 1, 1},
-				{1, 0, 1},
-				{1, 1, 1},
-			},
-			want: [][]int{
-				{0, 0, 0},
-				{0, 0, 0},
-				{0, 0, 0},
-			},
-		},
-		{
-			in: [][]int{
-				{1, 2, 3},
-				{4, 5, 6},
-				{7, 8, 9},
-			},
-			want: [][]int{
-				{3, 3, 4},
-				{4, 5, 5},
-				{6, 6, 7},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := imageSmoother(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/immediate-food-delivery-i/README.md b/problems/immediate-food-delivery-i/README.md
deleted file mode 100644
index 446d674e7..000000000
--- a/problems/immediate-food-delivery-i/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../dinner-plate-stacks "Dinner Plate Stacks")
-　　　　　　　　　　　　　　　　
-[Next >](../immediate-food-delivery-ii "Immediate Food Delivery II")
-
-## [1173. Immediate Food Delivery I (Easy)](https://leetcode.com/problems/immediate-food-delivery-i "即时食物配送 I")
-
-<p>Table: <code>Delivery</code></p>
-
-<pre>
-+-----------------------------+---------+
-| Column Name                 | Type    |
-+-----------------------------+---------+
-| delivery_id                 | int     |
-| customer_id                 | int     |
-| order_date                  | date    |
-| customer_pref_delivery_date | date    |
-+-----------------------------+---------+
-delivery_id is the primary key of this table.
-The table holds information about food delivery to customers that make orders at some date and specify a preferred delivery date (on the same order date or after it).
-</pre>
-
-<p>&nbsp;</p>
-
-<p>If the preferred delivery date of the customer is the same as the&nbsp;order date&nbsp;then the order is called <em>immediate</em>&nbsp;otherwise it&#39;s called <em>scheduled</em>.</p>
-
-<p>Write an SQL query to find the&nbsp;percentage of immediate orders in the table,&nbsp;<strong>rounded to 2 decimal places</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Delivery table:
-+-------------+-------------+------------+-----------------------------+
-| delivery_id | customer_id | order_date | customer_pref_delivery_date |
-+-------------+-------------+------------+-----------------------------+
-| 1           | 1           | 2019-08-01 | 2019-08-02                  |
-| 2           | 5           | 2019-08-02 | 2019-08-02                  |
-| 3           | 1           | 2019-08-11 | 2019-08-11                  |
-| 4           | 3           | 2019-08-24 | 2019-08-26                  |
-| 5           | 4           | 2019-08-21 | 2019-08-22                  |
-| 6           | 2           | 2019-08-11 | 2019-08-13                  |
-+-------------+-------------+------------+-----------------------------+
-
-Result table:
-+----------------------+
-| immediate_percentage |
-+----------------------+
-| 33.33                |
-+----------------------+
-The orders with delivery id 2 and 3 are immediate while the others are scheduled.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/immediate-food-delivery-i/mysql_schemas.sql b/problems/immediate-food-delivery-i/mysql_schemas.sql
deleted file mode 100644
index 25d9e735c..000000000
--- a/problems/immediate-food-delivery-i/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Delivery (delivery_id int, customer_id int, order_date date, customer_pref_delivery_date date);
-Truncate table Delivery;
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('1', '1', '2019-08-01', '2019-08-02');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('2', '5', '2019-08-02', '2019-08-02');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('3', '1', '2019-08-11', '2019-08-11');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('4', '3', '2019-08-24', '2019-08-26');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('5', '4', '2019-08-21', '2019-08-22');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('6', '2', '2019-08-11', '2019-08-13');
diff --git a/problems/immediate-food-delivery-ii/README.md b/problems/immediate-food-delivery-ii/README.md
deleted file mode 100644
index 69aa37ffd..000000000
--- a/problems/immediate-food-delivery-ii/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../immediate-food-delivery-i "Immediate Food Delivery I")
-　　　　　　　　　　　　　　　　
-[Next >](../prime-arrangements "Prime Arrangements")
-
-## [1174. Immediate Food Delivery II (Medium)](https://leetcode.com/problems/immediate-food-delivery-ii "即时食物配送 II")
-
-<p>Table: <code>Delivery</code></p>
-
-<pre>
-+-----------------------------+---------+
-| Column Name                 | Type    |
-+-----------------------------+---------+
-| delivery_id                 | int     |
-| customer_id                 | int     |
-| order_date                  | date    |
-| customer_pref_delivery_date | date    |
-+-----------------------------+---------+
-delivery_id is the primary key of this table.
-The table holds information about food delivery to customers that make orders at some date and specify a preferred delivery date (on the same order date or after it).
-</pre>
-
-<p>&nbsp;</p>
-
-<p>If the preferred delivery date of the customer is the same as the&nbsp;order date&nbsp;then the order is called <em>immediate</em>&nbsp;otherwise it&#39;s called <em>scheduled</em>.</p>
-
-<p>The&nbsp;<em>first order</em>&nbsp;of a customer is the order with the earliest order date that customer made. It is guaranteed that a customer has exactly one first order.</p>
-
-<p>Write an SQL query to find the&nbsp;percentage of immediate orders in the first orders of all customers,&nbsp;<strong>rounded to 2 decimal places</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Delivery table:
-+-------------+-------------+------------+-----------------------------+
-| delivery_id | customer_id | order_date | customer_pref_delivery_date |
-+-------------+-------------+------------+-----------------------------+
-| 1           | 1           | 2019-08-01 | 2019-08-02                  |
-| 2           | 2           | 2019-08-02 | 2019-08-02                  |
-| 3           | 1           | 2019-08-11 | 2019-08-12                  |
-| 4           | 3           | 2019-08-24 | 2019-08-24                  |
-| 5           | 3           | 2019-08-21 | 2019-08-22                  |
-| 6           | 2           | 2019-08-11 | 2019-08-13                  |
-| 7           | 4           | 2019-08-09 | 2019-08-09                  |
-+-------------+-------------+------------+-----------------------------+
-
-Result table:
-+----------------------+
-| immediate_percentage |
-+----------------------+
-| 50.00                |
-+----------------------+
-The customer id 1 has a first order with delivery id 1 and it is scheduled.
-The customer id 2 has a first order with delivery id 2 and it is immediate.
-The customer id 3 has a first order with delivery id 5 and it is scheduled.
-The customer id 4 has a first order with delivery id 7 and it is immediate.
-Hence, half the customers have immediate first orders.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/immediate-food-delivery-ii/mysql_schemas.sql b/problems/immediate-food-delivery-ii/mysql_schemas.sql
deleted file mode 100644
index da8430ded..000000000
--- a/problems/immediate-food-delivery-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Delivery (delivery_id int, customer_id int, order_date date, customer_pref_delivery_date date);
-Truncate table Delivery;
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('1', '1', '2019-08-01', '2019-08-02');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('2', '2', '2019-08-02', '2019-08-02');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('3', '1', '2019-08-11', '2019-08-12');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('4', '3', '2019-08-24', '2019-08-24');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('5', '3', '2019-08-21', '2019-08-22');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('6', '2', '2019-08-11', '2019-08-13');
-insert into Delivery (delivery_id, customer_id, order_date, customer_pref_delivery_date) values ('7', '4', '2019-08-09', '2019-08-09');
diff --git a/problems/implement-magic-dictionary/README.md b/problems/implement-magic-dictionary/README.md
deleted file mode 100644
index 212ba9254..000000000
--- a/problems/implement-magic-dictionary/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cut-off-trees-for-golf-event "Cut Off Trees for Golf Event")
-　　　　　　　　　　　　　　　　
-[Next >](../map-sum-pairs "Map Sum Pairs")
-
-## [676. Implement Magic Dictionary (Medium)](https://leetcode.com/problems/implement-magic-dictionary "实现一个魔法字典")
-
-<p>Design a data structure that is initialized with a list of <strong>different</strong> words. Provided a string, you should determine if you can change exactly one character in this string to match any word in the data structure.</p>
-
-<p>Implement the&nbsp;<code>MagicDictionary</code>&nbsp;class:</p>
-
-<ul>
-	<li><code>MagicDictionary()</code>&nbsp;Initializes the object.</li>
-	<li><code>void buildDict(String[]&nbsp;dictionary)</code>&nbsp;Sets the data structure&nbsp;with an array of distinct strings <code>dictionary</code>.</li>
-	<li><code>bool search(String searchWord)</code> Returns <code>true</code> if you can change <strong>exactly one character</strong> in <code>searchWord</code> to match any string in the data structure, otherwise returns <code>false</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MagicDictionary&quot;, &quot;buildDict&quot;, &quot;search&quot;, &quot;search&quot;, &quot;search&quot;, &quot;search&quot;]
-[[], [[&quot;hello&quot;, &quot;leetcode&quot;]], [&quot;hello&quot;], [&quot;hhllo&quot;], [&quot;hell&quot;], [&quot;leetcoded&quot;]]
-<strong>Output</strong>
-[null, null, false, true, false, false]
-
-<strong>Explanation</strong>
-MagicDictionary magicDictionary = new MagicDictionary();
-magicDictionary.buildDict([&quot;hello&quot;, &quot;leetcode&quot;]);
-magicDictionary.search(&quot;hello&quot;); // return False
-magicDictionary.search(&quot;hhllo&quot;); // We can change the second &#39;h&#39; to &#39;e&#39; to match &quot;hello&quot; so we return True
-magicDictionary.search(&quot;hell&quot;); // return False
-magicDictionary.search(&quot;leetcoded&quot;); // return False
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;dictionary.length &lt;= 100</code></li>
-	<li><code>1 &lt;=&nbsp;dictionary[i].length &lt;= 100</code></li>
-	<li><code>dictionary[i]</code> consists of only lower-case English letters.</li>
-	<li>All the strings in&nbsp;<code>dictionary</code>&nbsp;are <strong>distinct</strong>.</li>
-	<li><code>1 &lt;=&nbsp;searchWord.length &lt;= 100</code></li>
-	<li><code>searchWord</code>&nbsp;consists of only lower-case English letters.</li>
-	<li><code>buildDict</code>&nbsp;will be called only once before <code>search</code>.</li>
-	<li>At most <code>100</code> calls will be made to <code>search</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Similar Questions
-  1. [Implement Trie (Prefix Tree)](../implement-trie-prefix-tree) (Medium)
-  1. [Longest Word in Dictionary](../longest-word-in-dictionary) (Medium)
diff --git a/problems/implement-magic-dictionary/implement_magic_dictionary.go b/problems/implement-magic-dictionary/implement_magic_dictionary.go
deleted file mode 100644
index e141dd923..000000000
--- a/problems/implement-magic-dictionary/implement_magic_dictionary.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem676
diff --git a/problems/implement-magic-dictionary/implement_magic_dictionary_test.go b/problems/implement-magic-dictionary/implement_magic_dictionary_test.go
deleted file mode 100644
index e141dd923..000000000
--- a/problems/implement-magic-dictionary/implement_magic_dictionary_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem676
diff --git a/problems/implement-queue-using-stacks/README.md b/problems/implement-queue-using-stacks/README.md
deleted file mode 100644
index 6fc28351e..000000000
--- a/problems/implement-queue-using-stacks/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../power-of-two "Power of Two")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-digit-one "Number of Digit One")
-
-## [232. Implement Queue using Stacks (Easy)](https://leetcode.com/problems/implement-queue-using-stacks "用栈实现队列")
-
-<p>Implement a first in first out (FIFO) queue using only two stacks. The implemented queue should support all the functions of a normal queue (<code>push</code>, <code>peek</code>, <code>pop</code>, and <code>empty</code>).</p>
-
-<p>Implement the <code>MyQueue</code> class:</p>
-
-<ul>
-	<li><code>void push(int x)</code> Pushes element x to the back of the queue.</li>
-	<li><code>int pop()</code> Removes the element from the front of the queue and returns it.</li>
-	<li><code>int peek()</code> Returns the element at the front of the queue.</li>
-	<li><code>boolean empty()</code> Returns <code>true</code> if the queue is empty, <code>false</code> otherwise.</li>
-</ul>
-
-<p><strong>Notes:</strong></p>
-
-<ul>
-	<li>You must use <strong>only</strong> standard operations of a stack, which means only <code>push to top</code>, <code>peek/pop from top</code>, <code>size</code>, and <code>is empty</code> operations are valid.</li>
-	<li>Depending on your language, the stack may not be supported natively. You may simulate a stack using a list or deque (double-ended queue) as long as you use only a stack&#39;s standard operations.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyQueue&quot;, &quot;push&quot;, &quot;push&quot;, &quot;peek&quot;, &quot;pop&quot;, &quot;empty&quot;]
-[[], [1], [2], [], [], []]
-<strong>Output</strong>
-[null, null, null, 1, 1, false]
-
-<strong>Explanation</strong>
-MyQueue myQueue = new MyQueue();
-myQueue.push(1); // queue is: [1]
-myQueue.push(2); // queue is: [1, 2] (leftmost is front of the queue)
-myQueue.peek(); // return 1
-myQueue.pop(); // return 1, queue is [2]
-myQueue.empty(); // return false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= x &lt;= 9</code></li>
-	<li>At most <code>100</code>&nbsp;calls will be made to <code>push</code>, <code>pop</code>, <code>peek</code>, and <code>empty</code>.</li>
-	<li>All the calls to <code>pop</code> and <code>peek</code> are valid.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow-up:</strong> Can you implement the queue such that each operation is <strong><a href="https://en.wikipedia.org/wiki/Amortized_analysis" target="_blank">amortized</a></strong> <code>O(1)</code> time complexity? In other words, performing <code>n</code> operations will take overall <code>O(n)</code> time even if one of those operations may take longer.</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-
-### Similar Questions
-  1. [Implement Stack using Queues](../implement-stack-using-queues) (Easy)
diff --git a/problems/implement-queue-using-stacks/implement_queue_using_stacks.go b/problems/implement-queue-using-stacks/implement_queue_using_stacks.go
deleted file mode 100644
index 14a6fc969..000000000
--- a/problems/implement-queue-using-stacks/implement_queue_using_stacks.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem232
diff --git a/problems/implement-queue-using-stacks/implement_queue_using_stacks_test.go b/problems/implement-queue-using-stacks/implement_queue_using_stacks_test.go
deleted file mode 100644
index 14a6fc969..000000000
--- a/problems/implement-queue-using-stacks/implement_queue_using_stacks_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem232
diff --git a/problems/implement-rand10-using-rand7/README.md b/problems/implement-rand10-using-rand7/README.md
deleted file mode 100644
index 9a1d23cdc..000000000
--- a/problems/implement-rand10-using-rand7/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convex-polygon "Convex Polygon")
-　　　　　　　　　　　　　　　　
-[Next >](../encode-string-with-shortest-length "Encode String with Shortest Length")
-
-## [470. Implement Rand10() Using Rand7() (Medium)](https://leetcode.com/problems/implement-rand10-using-rand7 "用 Rand7() 实现 Rand10()")
-
-<p>Given the <strong>API</strong> <code>rand7()</code> that generates a uniform random integer in the range <code>[1, 7]</code>, write a function <code>rand10()</code> that generates a uniform random integer in the range <code>[1, 10]</code>. You can only call the API <code>rand7()</code>, and you shouldn&#39;t call any other API. Please <strong>do not</strong> use a language&#39;s built-in random API.</p>
-
-<p>Each test case will have one <strong>internal</strong> argument <code>n</code>, the number of times that your implemented function <code>rand10()</code> will be called while testing. Note that this is <strong>not an argument</strong> passed to <code>rand10()</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 1
-<strong>Output:</strong> [2]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 2
-<strong>Output:</strong> [2,8]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> n = 3
-<strong>Output:</strong> [3,8,10]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>What is the <a href="https://en.wikipedia.org/wiki/Expected_value" target="_blank">expected value</a> for the number of calls to <code>rand7()</code> function?</li>
-	<li>Could you minimize the number of calls to <code>rand7()</code>?</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Rejection Sampling](../../tag/rejection-sampling/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-  [[Probability and Statistics](../../tag/probability-and-statistics/README.md)]
diff --git a/problems/implement-rand10-using-rand7/implement_rand10_using_rand7.go b/problems/implement-rand10-using-rand7/implement_rand10_using_rand7.go
deleted file mode 100644
index 5ede42b81..000000000
--- a/problems/implement-rand10-using-rand7/implement_rand10_using_rand7.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem470
diff --git a/problems/implement-rand10-using-rand7/implement_rand10_using_rand7_test.go b/problems/implement-rand10-using-rand7/implement_rand10_using_rand7_test.go
deleted file mode 100644
index 5ede42b81..000000000
--- a/problems/implement-rand10-using-rand7/implement_rand10_using_rand7_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem470
diff --git a/problems/implement-stack-using-queues/README.md b/problems/implement-stack-using-queues/README.md
deleted file mode 100644
index 995ea9b60..000000000
--- a/problems/implement-stack-using-queues/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../basic-calculator "Basic Calculator")
-　　　　　　　　　　　　　　　　
-[Next >](../invert-binary-tree "Invert Binary Tree")
-
-## [225. Implement Stack using Queues (Easy)](https://leetcode.com/problems/implement-stack-using-queues "用队列实现栈")
-
-<p>Implement a last-in-first-out (LIFO) stack using only two queues. The implemented stack should support all the functions of a normal stack (<code>push</code>, <code>top</code>, <code>pop</code>, and <code>empty</code>).</p>
-
-<p>Implement the <code>MyStack</code> class:</p>
-
-<ul>
-	<li><code>void push(int x)</code> Pushes element x to the top of the stack.</li>
-	<li><code>int pop()</code> Removes the element on the top of the stack and returns it.</li>
-	<li><code>int top()</code> Returns the element on the top of the stack.</li>
-	<li><code>boolean empty()</code> Returns <code>true</code> if the stack is empty, <code>false</code> otherwise.</li>
-</ul>
-
-<p><b>Notes:</b></p>
-
-<ul>
-	<li>You must use <strong>only</strong> standard operations of a queue, which means that only <code>push to back</code>, <code>peek/pop from front</code>, <code>size</code> and <code>is empty</code> operations are valid.</li>
-	<li>Depending on your language, the queue may not be supported natively. You may simulate a queue using a list or deque (double-ended queue) as long as you use only a queue&#39;s standard operations.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyStack&quot;, &quot;push&quot;, &quot;push&quot;, &quot;top&quot;, &quot;pop&quot;, &quot;empty&quot;]
-[[], [1], [2], [], [], []]
-<strong>Output</strong>
-[null, null, null, 2, 2, false]
-
-<strong>Explanation</strong>
-MyStack myStack = new MyStack();
-myStack.push(1);
-myStack.push(2);
-myStack.top(); // return 2
-myStack.pop(); // return 2
-myStack.empty(); // return False
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= x &lt;= 9</code></li>
-	<li>At most <code>100</code> calls will be made to <code>push</code>, <code>pop</code>, <code>top</code>, and <code>empty</code>.</li>
-	<li>All the calls to <code>pop</code> and <code>top</code> are valid.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow-up:</strong> Can you implement the stack using only one queue?</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-
-### Similar Questions
-  1. [Implement Queue using Stacks](../implement-queue-using-stacks) (Easy)
diff --git a/problems/implement-stack-using-queues/implement_stack_using_queues.go b/problems/implement-stack-using-queues/implement_stack_using_queues.go
deleted file mode 100644
index 99a8928f5..000000000
--- a/problems/implement-stack-using-queues/implement_stack_using_queues.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem225
diff --git a/problems/implement-stack-using-queues/implement_stack_using_queues_test.go b/problems/implement-stack-using-queues/implement_stack_using_queues_test.go
deleted file mode 100644
index 99a8928f5..000000000
--- a/problems/implement-stack-using-queues/implement_stack_using_queues_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem225
diff --git a/problems/implement-strstr/README.md b/problems/implement-strstr/README.md
deleted file mode 100644
index a744c0b83..000000000
--- a/problems/implement-strstr/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-element "Remove Element")
-　　　　　　　　　　　　　　　　
-[Next >](../divide-two-integers "Divide Two Integers")
-
-## [28. Implement strStr() (Easy)](https://leetcode.com/problems/implement-strstr "实现 strStr()")
-
-<p>Implement <a href="http://www.cplusplus.com/reference/cstring/strstr/" target="_blank">strStr()</a>.</p>
-
-<p>Return the index of the first occurrence of needle in haystack, or <code>-1</code> if <code>needle</code> is not part of <code>haystack</code>.</p>
-
-<p><strong>Clarification:</strong></p>
-
-<p>What should we return when <code>needle</code> is an empty string? This is a great question to ask during an interview.</p>
-
-<p>For the purpose of this problem, we will return 0 when <code>needle</code> is an empty string. This is consistent to C&#39;s&nbsp;<a href="http://www.cplusplus.com/reference/cstring/strstr/" target="_blank">strstr()</a> and Java&#39;s&nbsp;<a href="https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#indexOf(java.lang.String)" target="_blank">indexOf()</a>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> haystack = "hello", needle = "ll"
-<strong>Output:</strong> 2
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> haystack = "aaaaa", needle = "bba"
-<strong>Output:</strong> -1
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> haystack = "", needle = ""
-<strong>Output:</strong> 0
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= haystack.length, needle.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>haystack</code> and&nbsp;<code>needle</code> consist of only lower-case English characters.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Similar Questions
-  1. [Shortest Palindrome](../shortest-palindrome) (Hard)
-  1. [Repeated Substring Pattern](../repeated-substring-pattern) (Easy)
diff --git a/problems/implement-strstr/implement_strstr.go b/problems/implement-strstr/implement_strstr.go
deleted file mode 100644
index 2f50cfbec..000000000
--- a/problems/implement-strstr/implement_strstr.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem28
-
-import "strings"
-
-func strStr(haystack string, needle string) int {
-	return strings.Index(haystack, needle)
-}
diff --git a/problems/implement-strstr/implement_strstr_test.go b/problems/implement-strstr/implement_strstr_test.go
deleted file mode 100644
index 9cc25a1d9..000000000
--- a/problems/implement-strstr/implement_strstr_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem28
-
-import "testing"
-
-type testType struct {
-	haystack string
-	needle   string
-	want     int
-}
-
-func TestStrStr(t *testing.T) {
-	tests := [...]testType{
-		{
-			haystack: "hello",
-			needle:   "ll",
-			want:     2,
-		}, {
-			haystack: "this is test string",
-			needle:   "a",
-			want:     -1,
-		},
-	}
-
-	for _, tt := range tests {
-		got := strStr(tt.haystack, tt.needle)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.haystack, tt.needle, got, tt.want)
-		}
-	}
-}
diff --git a/problems/implement-trie-ii-prefix-tree/README.md b/problems/implement-trie-ii-prefix-tree/README.md
deleted file mode 100644
index f7c7d2d56..000000000
--- a/problems/implement-trie-ii-prefix-tree/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-pairs-with-xor-in-a-range "Count Pairs With XOR in a Range")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-different-integers-in-a-string "Number of Different Integers in a String")
-
-## [1804. Implement Trie II (Prefix Tree) (Medium)](https://leetcode.com/problems/implement-trie-ii-prefix-tree "实现 Trie （前缀树） II")
-
-
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to solve the first version first and reuse your code.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To implement the delete function, you should delete the trie nodes of the word if they are not shared with other words.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You should keep for each trie node a counter of how many words share this node.
-</details>
diff --git a/problems/implement-trie-prefix-tree/README.md b/problems/implement-trie-prefix-tree/README.md
deleted file mode 100644
index 50d2495c9..000000000
--- a/problems/implement-trie-prefix-tree/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../course-schedule "Course Schedule")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-size-subarray-sum "Minimum Size Subarray Sum")
-
-## [208. Implement Trie (Prefix Tree) (Medium)](https://leetcode.com/problems/implement-trie-prefix-tree "实现 Trie (前缀树)")
-
-<p>A <a href="https://en.wikipedia.org/wiki/Trie" target="_blank"><strong>trie</strong></a> (pronounced as &quot;try&quot;) or <strong>prefix tree</strong> is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker.</p>
-
-<p>Implement the Trie class:</p>
-
-<ul>
-	<li><code>Trie()</code> Initializes the trie object.</li>
-	<li><code>void insert(String word)</code> Inserts the string <code>word</code> into the trie.</li>
-	<li><code>boolean search(String word)</code> Returns <code>true</code> if the string <code>word</code> is in the trie (i.e., was inserted before), and <code>false</code> otherwise.</li>
-	<li><code>boolean startsWith(String prefix)</code> Returns <code>true</code> if there is a previously inserted string <code>word</code> that has the prefix <code>prefix</code>, and <code>false</code> otherwise.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Trie&quot;, &quot;insert&quot;, &quot;search&quot;, &quot;search&quot;, &quot;startsWith&quot;, &quot;insert&quot;, &quot;search&quot;]
-[[], [&quot;apple&quot;], [&quot;apple&quot;], [&quot;app&quot;], [&quot;app&quot;], [&quot;app&quot;], [&quot;app&quot;]]
-<strong>Output</strong>
-[null, null, true, false, true, null, true]
-
-<strong>Explanation</strong>
-Trie trie = new Trie();
-trie.insert(&quot;apple&quot;);
-trie.search(&quot;apple&quot;);   // return True
-trie.search(&quot;app&quot;);     // return False
-trie.startsWith(&quot;app&quot;); // return True
-trie.insert(&quot;app&quot;);
-trie.search(&quot;app&quot;);     // return True
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length, prefix.length &lt;= 2000</code></li>
-	<li><code>word</code> and <code>prefix</code> consist only of lowercase English letters.</li>
-	<li>At most <code>3 * 10<sup>4</sup></code> calls <strong>in total</strong> will be made to <code>insert</code>, <code>search</code>, and <code>startsWith</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Design Add and Search Words Data Structure](../design-add-and-search-words-data-structure) (Medium)
-  1. [Design Search Autocomplete System](../design-search-autocomplete-system) (Hard)
-  1. [Replace Words](../replace-words) (Medium)
-  1. [Implement Magic Dictionary](../implement-magic-dictionary) (Medium)
diff --git a/problems/implement-trie-prefix-tree/implement_trie_prefix_tree.go b/problems/implement-trie-prefix-tree/implement_trie_prefix_tree.go
deleted file mode 100644
index 610752147..000000000
--- a/problems/implement-trie-prefix-tree/implement_trie_prefix_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem208
diff --git a/problems/implement-trie-prefix-tree/implement_trie_prefix_tree_test.go b/problems/implement-trie-prefix-tree/implement_trie_prefix_tree_test.go
deleted file mode 100644
index 610752147..000000000
--- a/problems/implement-trie-prefix-tree/implement_trie_prefix_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem208
diff --git a/problems/increasing-decreasing-string/README.md b/problems/increasing-decreasing-string/README.md
deleted file mode 100644
index 8a62e65a2..000000000
--- a/problems/increasing-decreasing-string/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../get-the-second-most-recent-activity "Get the Second Most Recent Activity")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-longest-substring-containing-vowels-in-even-counts "Find the Longest Substring Containing Vowels in Even Counts")
-
-## [1370. Increasing Decreasing String (Easy)](https://leetcode.com/problems/increasing-decreasing-string "上升下降字符串")
-
-<p>You are given a string <code>s</code>. Reorder the string using the following algorithm:</p>
-
-<ol>
-	<li>Pick the <strong>smallest</strong> character from <code>s</code> and <strong>append</strong> it to the result.</li>
-	<li>Pick the <strong>smallest</strong> character from <code>s</code> which is greater than the last appended character to the result and <strong>append</strong> it.</li>
-	<li>Repeat step 2 until you cannot pick more characters.</li>
-	<li>Pick the <strong>largest</strong> character from <code>s</code> and <strong>append</strong> it to the result.</li>
-	<li>Pick the <strong>largest</strong> character from <code>s</code> which is smaller than the last appended character to the result and <strong>append</strong> it.</li>
-	<li>Repeat step 5 until you cannot pick more characters.</li>
-	<li>Repeat the steps from 1 to 6 until you pick all characters from <code>s</code>.</li>
-</ol>
-
-<p>In each step, If the smallest or the largest character appears more than once you can choose any occurrence and append it to the result.</p>
-
-<p>Return <em>the result string after sorting </em><code>s</code><em> with this algorithm</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaaabbbbcccc&quot;
-<strong>Output:</strong> &quot;abccbaabccba&quot;
-<strong>Explanation:</strong> After steps 1, 2 and 3 of the first iteration, result = &quot;abc&quot;
-After steps 4, 5 and 6 of the first iteration, result = &quot;abccba&quot;
-First iteration is done. Now s = &quot;aabbcc&quot; and we go back to step 1
-After steps 1, 2 and 3 of the second iteration, result = &quot;abccbaabc&quot;
-After steps 4, 5 and 6 of the second iteration, result = &quot;abccbaabccba&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;rat&quot;
-<strong>Output:</strong> &quot;art&quot;
-<strong>Explanation:</strong> The word &quot;rat&quot; becomes &quot;art&quot; after re-ordering it with the mentioned algorithm.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 500</code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the frequency of each character.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop over all character from 'a' to 'z' and append the character if it exists and decrease frequency by 1. Do the same from 'z' to 'a'.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Keep repeating until the frequency of all characters is zero.
-</details>
diff --git a/problems/increasing-decreasing-string/increasing_decreasing_string.go b/problems/increasing-decreasing-string/increasing_decreasing_string.go
deleted file mode 100644
index 9d939beb1..000000000
--- a/problems/increasing-decreasing-string/increasing_decreasing_string.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package problem1370
-
-func sortString(s string) string {
-	var m [26]int
-	for _, c := range s {
-		m[c-'a']++
-	}
-	l := len(s)
-	ans := make([]byte, 0, l)
-	appendChar := func(c int) {
-		if m[c] > 0 {
-			m[c]--
-			l--
-			ans = append(ans, byte(c+'a'))
-		}
-	}
-	for l > 0 {
-		for i := 0; i <= 25; i++ {
-			appendChar(i)
-		}
-		for i := 25; i >= 0; i-- {
-			appendChar(i)
-		}
-	}
-	return string(ans)
-}
diff --git a/problems/increasing-decreasing-string/increasing_decreasing_string_test.go b/problems/increasing-decreasing-string/increasing_decreasing_string_test.go
deleted file mode 100644
index 562fd3e14..000000000
--- a/problems/increasing-decreasing-string/increasing_decreasing_string_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem1370
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestSortString(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "aaaabbbbcccc",
-			want: "abccbaabccba",
-		},
-		{
-			in:   "rat",
-			want: "art",
-		},
-		{
-			in:   "leetcode",
-			want: "cdelotee",
-		},
-		{
-			in:   "ggggggg",
-			want: "ggggggg",
-		},
-		{
-			in:   "spo",
-			want: "ops",
-		},
-	}
-	for _, tt := range tests {
-		got := sortString(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/increasing-order-search-tree/README.md b/problems/increasing-order-search-tree/README.md
deleted file mode 100644
index 0d79507af..000000000
--- a/problems/increasing-order-search-tree/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../monotonic-array "Monotonic Array")
-　　　　　　　　　　　　　　　　
-[Next >](../bitwise-ors-of-subarrays "Bitwise ORs of Subarrays")
-
-## [897. Increasing Order Search Tree (Easy)](https://leetcode.com/problems/increasing-order-search-tree "递增顺序搜索树")
-
-<p>Given the <code>root</code> of a binary search tree, rearrange the tree in <strong>in-order</strong> so that the leftmost node in the tree is now the root of the tree, and every node has no left child and only one right child.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/17/ex1.jpg" style="width: 600px; height: 350px;" />
-<pre>
-<strong>Input:</strong> root = [5,3,6,2,4,null,8,1,null,null,null,7,9]
-<strong>Output:</strong> [1,null,2,null,3,null,4,null,5,null,6,null,7,null,8,null,9]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/17/ex2.jpg" style="width: 300px; height: 114px;" />
-<pre>
-<strong>Input:</strong> root = [5,1,7]
-<strong>Output:</strong> [1,null,5,null,7]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the given tree will be in the range <code>[1, 100]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/increasing-order-search-tree/increasing_order_search_tree.go b/problems/increasing-order-search-tree/increasing_order_search_tree.go
deleted file mode 100644
index fed0cd287..000000000
--- a/problems/increasing-order-search-tree/increasing_order_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem897
diff --git a/problems/increasing-order-search-tree/increasing_order_search_tree_test.go b/problems/increasing-order-search-tree/increasing_order_search_tree_test.go
deleted file mode 100644
index fed0cd287..000000000
--- a/problems/increasing-order-search-tree/increasing_order_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem897
diff --git a/problems/increasing-subsequences/README.md b/problems/increasing-subsequences/README.md
deleted file mode 100644
index 23795c8b3..000000000
--- a/problems/increasing-subsequences/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-maze "The Maze")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-the-rectangle "Construct the Rectangle")
-
-## [491. Increasing Subsequences (Medium)](https://leetcode.com/problems/increasing-subsequences "递增子序列")
-
-<p>Given an integer array <code>nums</code>, return all the different possible increasing subsequences of the given array with <strong>at least two elements</strong>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>The given array may contain duplicates, and two equal integers should also be considered a special case of increasing sequence.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,6,7,7]
-<strong>Output:</strong> [[4,6],[4,6,7],[4,6,7,7],[4,7],[4,7,7],[6,7],[6,7,7],[7,7]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,4,3,2,1]
-<strong>Output:</strong> [[4,4]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 15</code></li>
-	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Maximum Length of Pair Chain](../maximum-length-of-pair-chain) (Medium)
diff --git a/problems/increasing-subsequences/increasing_subsequences.go b/problems/increasing-subsequences/increasing_subsequences.go
deleted file mode 100644
index 0861acfbc..000000000
--- a/problems/increasing-subsequences/increasing_subsequences.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem491
diff --git a/problems/increasing-subsequences/increasing_subsequences_test.go b/problems/increasing-subsequences/increasing_subsequences_test.go
deleted file mode 100644
index 0861acfbc..000000000
--- a/problems/increasing-subsequences/increasing_subsequences_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem491
diff --git a/problems/increasing-triplet-subsequence/README.md b/problems/increasing-triplet-subsequence/README.md
deleted file mode 100644
index 8c9db9595..000000000
--- a/problems/increasing-triplet-subsequence/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-bst-subtree "Largest BST Subtree")
-　　　　　　　　　　　　　　　　
-[Next >](../self-crossing "Self Crossing")
-
-## [334. Increasing Triplet Subsequence (Medium)](https://leetcode.com/problems/increasing-triplet-subsequence "递增的三元子序列")
-
-<p>Given an integer array <code>nums</code>, return <code>true</code><em> if there exists a triple of indices </em><code>(i, j, k)</code><em> such that </em><code>i &lt; j &lt; k</code><em> and </em><code>nums[i] &lt; nums[j] &lt; nums[k]</code>. If no such indices exists, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Any triplet where i &lt; j &lt; k is valid.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,4,3,2,1]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> No triplet exists.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,5,0,4,6]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The triplet (3, 4, 5) is valid because nums[3] == 0 &lt; nums[4] == 4 &lt; nums[5] == 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>5</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you implement a solution that runs in <code>O(n)</code> time complexity and <code>O(1)</code> space complexity?
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Longest Increasing Subsequence](../longest-increasing-subsequence) (Medium)
diff --git a/problems/increasing-triplet-subsequence/increasing_triplet_subsequence.go b/problems/increasing-triplet-subsequence/increasing_triplet_subsequence.go
deleted file mode 100644
index 08e8a16b7..000000000
--- a/problems/increasing-triplet-subsequence/increasing_triplet_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem334
diff --git a/problems/increasing-triplet-subsequence/increasing_triplet_subsequence_test.go b/problems/increasing-triplet-subsequence/increasing_triplet_subsequence_test.go
deleted file mode 100644
index 08e8a16b7..000000000
--- a/problems/increasing-triplet-subsequence/increasing_triplet_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem334
diff --git a/problems/incremental-memory-leak/README.md b/problems/incremental-memory-leak/README.md
deleted file mode 100644
index 17c716d16..000000000
--- a/problems/incremental-memory-leak/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sorting-the-sentence "Sorting the Sentence")
-　　　　　　　　　　　　　　　　
-[Next >](../rotating-the-box "Rotating the Box")
-
-## [1860. Incremental Memory Leak (Medium)](https://leetcode.com/problems/incremental-memory-leak "增长的内存泄露")
-
-<p>You are given two integers <code>memory1</code> and <code>memory2</code> representing the available memory in bits on two memory sticks. There is currently a faulty program running that consumes an increasing amount of memory every second.</p>
-
-<p>At the <code>i<sup>th</sup></code> second (starting from 1), <code>i</code> bits of memory are allocated to the stick with <strong>more available memory</strong> (or from the first memory stick if both have the same available memory). If neither stick has at least <code>i</code> bits of available memory, the program <strong>crashes</strong>.</p>
-
-<p>Return <em>an array containing </em><code>[crashTime, memory1<sub>crash</sub>, memory2<sub>crash</sub>]</code><em>, where </em><code>crashTime</code><em> is the time (in seconds) when the program crashed and </em><code>memory1<sub>crash</sub></code><em> and </em><code>memory2<sub>crash</sub></code><em> are the available bits of memory in the first and second sticks respectively</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> memory1 = 2, memory2 = 2
-<strong>Output:</strong> [3,1,0]
-<strong>Explanation:</strong> The memory is allocated as follows:
-- At the 1<sup>st</sup> second, 1 bit of memory is allocated to stick 1. The first stick now has 1 bit of available memory.
-- At the 2<sup>nd</sup> second, 2 bits of memory are allocated to stick 2. The second stick now has 0 bits of available memory.
-- At the 3<sup>rd</sup> second, the program crashes. The sticks have 1 and 0 bits available respectively.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> memory1 = 8, memory2 = 11
-<strong>Output:</strong> [6,0,4]
-<strong>Explanation:</strong> The memory is allocated as follows:
-- At the 1<sup>st</sup> second, 1 bit of memory is allocated to stick 2. The second stick now has 10 bit of available memory.
-- At the 2<sup>nd</sup> second, 2 bits of memory are allocated to stick 2. The second stick now has 8 bits of available memory.
-- At the 3<sup>rd</sup> second, 3 bits of memory are allocated to stick 1. The first stick now has 5 bits of available memory.
-- At the 4<sup>th</sup> second, 4 bits of memory are allocated to stick 2. The second stick now has 4 bits of available memory.
-- At the 5<sup>th</sup> second, 5 bits of memory are allocated to stick 1. The first stick now has 0 bits of available memory.
-- At the 6<sup>th</sup> second, the program crashes. The sticks have 0 and 4 bits available respectively.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= memory1, memory2 &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What is the upper bound for the number of seconds?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Simulate the process of allocating memory.
-</details>
diff --git a/problems/index-pairs-of-a-string/README.md b/problems/index-pairs-of-a-string/README.md
deleted file mode 100644
index 69275ff74..000000000
--- a/problems/index-pairs-of-a-string/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fixed-point "Fixed Point")
-　　　　　　　　　　　　　　　　
-[Next >](../campus-bikes-ii "Campus Bikes II")
-
-## [1065. Index Pairs of a String (Easy)](https://leetcode.com/problems/index-pairs-of-a-string "字符串的索引对")
-
-<p>Given a <code>text</code>&nbsp;string and <code>words</code> (a list of strings), return all index pairs <code>[i, j]</code> so that the substring <code>text[i]...text[j]</code>&nbsp;is in the list of <code>words</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>text = <span id="example-input-1-1">&quot;thestoryofleetcodeandme&quot;</span>, words = <span id="example-input-1-2">[&quot;story&quot;,&quot;fleet&quot;,&quot;leetcode&quot;]</span>
-<strong>Output: </strong><span id="example-output-1">[[3,7],[9,13],[10,17]]</span>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>text = <span id="example-input-2-1">&quot;ababa&quot;</span>, words = <span id="example-input-2-2">[&quot;aba&quot;,&quot;ab&quot;]</span>
-<strong>Output: </strong><span id="example-output-2">[[0,1],[0,2],[2,3],[2,4]]</span>
-<strong>Explanation: </strong>
-Notice that matches can overlap, see &quot;aba&quot; is found in [0,2] and [2,4].
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>All strings contains only lowercase English letters.</li>
-	<li>It&#39;s guaranteed that all strings in <code>words</code> are different.</li>
-	<li><code>1 &lt;= text.length &lt;= 100</code></li>
-	<li><code>1 &lt;= words.length &lt;= 20</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 50</code></li>
-	<li>Return the pairs <code>[i,j]</code> in sorted order (i.e. sort them by their first coordinate in case of ties sort them by their second coordinate).</li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each string of the set, look for matches and store those matches indices.
-</details>
diff --git a/problems/inorder-successor-in-bst-ii/README.md b/problems/inorder-successor-in-bst-ii/README.md
deleted file mode 100644
index 296fe42ec..000000000
--- a/problems/inorder-successor-in-bst-ii/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fibonacci-number "Fibonacci Number")
-　　　　　　　　　　　　　　　　
-[Next >](../game-play-analysis-i "Game Play Analysis I")
-
-## [510. Inorder Successor in BST II (Medium)](https://leetcode.com/problems/inorder-successor-in-bst-ii "二叉搜索树中的中序后继 II")
-
-<p>Given a binary search tree and a node in it, find the in-order successor of that node in the BST.</p>
-
-<p>The successor of a node <code>p</code> is the node with the smallest key greater than <code>p.val</code>.</p>
-
-<p>You will have direct access to the node but not to the root of the tree. Each node will have a reference to its parent node.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/23/285_example_1.PNG" style="width: 122px; height: 117px;" />
-<pre>
-<strong>Input: </strong>
-root = <span id="example-input-1-1">{&quot;$id&quot;:&quot;1&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;2&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;1&quot;},&quot;right&quot;:null,&quot;val&quot;:1},&quot;parent&quot;:null,&quot;right&quot;:{&quot;$id&quot;:&quot;3&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;1&quot;},&quot;right&quot;:null,&quot;val&quot;:3},&quot;val&quot;:2}</span>
-p = <span id="example-input-1-2">1</span>
-<strong>Output: </strong><span id="example-output-1">2</span>
-<strong>Explanation: </strong>1&#39;s in-order successor node is 2. Note that both p and the return value is of Node type.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/23/285_example_2.PNG" style="width: 246px; height: 229px;" />
-<pre>
-<strong>Input: </strong>
-root = <span id="example-input-2-1">{&quot;$id&quot;:&quot;1&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;2&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;3&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;4&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;3&quot;},&quot;right&quot;:null,&quot;val&quot;:1},&quot;parent&quot;:{&quot;$ref&quot;:&quot;2&quot;},&quot;right&quot;:null,&quot;val&quot;:2},&quot;parent&quot;:{&quot;$ref&quot;:&quot;1&quot;},&quot;right&quot;:{&quot;$id&quot;:&quot;5&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;2&quot;},&quot;right&quot;:null,&quot;val&quot;:4},&quot;val&quot;:3},&quot;parent&quot;:null,&quot;right&quot;:{&quot;$id&quot;:&quot;6&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;1&quot;},&quot;right&quot;:null,&quot;val&quot;:6},&quot;val&quot;:5}</span>
-p = <span id="example-input-2-2">6</span>
-<strong>Output: </strong><span id="example-output-2">null</span>
-<strong>Explanation: </strong>There is no in-order successor of the current node, so the answer is <code>null</code>.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/02/285_example_34.PNG" style="width: 438px; height: 335px;" />
-<pre>
-<strong>Input: </strong>
-root = <span id="example-input-2-1">{&quot;$id&quot;:&quot;1&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;2&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;3&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;4&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;3&quot;},&quot;right&quot;:null,&quot;val&quot;:2},&quot;parent&quot;:{&quot;$ref&quot;:&quot;2&quot;},&quot;right&quot;:{&quot;$id&quot;:&quot;5&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;3&quot;},&quot;right&quot;:null,&quot;val&quot;:4},&quot;val&quot;:3},&quot;parent&quot;:{&quot;$ref&quot;:&quot;1&quot;},&quot;right&quot;:{&quot;$id&quot;:&quot;6&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;2&quot;},&quot;right&quot;:{&quot;$id&quot;:&quot;7&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;8&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;7&quot;},&quot;right&quot;:null,&quot;val&quot;:9},&quot;parent&quot;:{&quot;$ref&quot;:&quot;6&quot;},&quot;right&quot;:null,&quot;val&quot;:13},&quot;val&quot;:7},&quot;val&quot;:6},&quot;parent&quot;:null,&quot;right&quot;:{&quot;$id&quot;:&quot;9&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;10&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;9&quot;},&quot;right&quot;:null,&quot;val&quot;:17},&quot;parent&quot;:{&quot;$ref&quot;:&quot;1&quot;},&quot;right&quot;:{&quot;$id&quot;:&quot;11&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;9&quot;},&quot;right&quot;:null,&quot;val&quot;:20},&quot;val&quot;:18},&quot;val&quot;:15}</span>
-p = <span id="example-input-2-2">15</span>
-<strong>Output: </strong><span id="example-output-2">17</span>
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/02/285_example_34.PNG" style="width: 438px; height: 335px;" />
-<pre>
-<strong>Input: </strong>
-root = <span id="example-input-2-1">{&quot;$id&quot;:&quot;1&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;2&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;3&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;4&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;3&quot;},&quot;right&quot;:null,&quot;val&quot;:2},&quot;parent&quot;:{&quot;$ref&quot;:&quot;2&quot;},&quot;right&quot;:{&quot;$id&quot;:&quot;5&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;3&quot;},&quot;right&quot;:null,&quot;val&quot;:4},&quot;val&quot;:3},&quot;parent&quot;:{&quot;$ref&quot;:&quot;1&quot;},&quot;right&quot;:{&quot;$id&quot;:&quot;6&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;2&quot;},&quot;right&quot;:{&quot;$id&quot;:&quot;7&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;8&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;7&quot;},&quot;right&quot;:null,&quot;val&quot;:9},&quot;parent&quot;:{&quot;$ref&quot;:&quot;6&quot;},&quot;right&quot;:null,&quot;val&quot;:13},&quot;val&quot;:7},&quot;val&quot;:6},&quot;parent&quot;:null,&quot;right&quot;:{&quot;$id&quot;:&quot;9&quot;,&quot;left&quot;:{&quot;$id&quot;:&quot;10&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;9&quot;},&quot;right&quot;:null,&quot;val&quot;:17},&quot;parent&quot;:{&quot;$ref&quot;:&quot;1&quot;},&quot;right&quot;:{&quot;$id&quot;:&quot;11&quot;,&quot;left&quot;:null,&quot;parent&quot;:{&quot;$ref&quot;:&quot;9&quot;},&quot;right&quot;:null,&quot;val&quot;:20},&quot;val&quot;:18},&quot;val&quot;:15}</span>
-p = <span id="example-input-2-2">13</span>
-<strong>Output: </strong><span id="example-output-2">15</span>
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>If the given node has no in-order successor in the tree, return <code>null</code>.</li>
-	<li>It&#39;s guaranteed that the values of the tree are unique.</li>
-	<li>Remember that we are using the <code>Node</code> type instead of <code>TreeNode</code> type so their string representation are different.</li>
-</ol>
-
-<p>&nbsp;</p>
-
-<p><strong>Follow up:</strong></p>
-
-<p>Could you solve&nbsp;it without&nbsp;looking up any of the&nbsp;node&#39;s values?</p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Inorder Successor in BST](../inorder-successor-in-bst) (Medium)
diff --git a/problems/inorder-successor-in-bst/README.md b/problems/inorder-successor-in-bst/README.md
deleted file mode 100644
index f81ac9086..000000000
--- a/problems/inorder-successor-in-bst/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../peeking-iterator "Peeking Iterator")
-　　　　　　　　　　　　　　　　
-[Next >](../walls-and-gates "Walls and Gates")
-
-## [285. Inorder Successor in BST (Medium)](https://leetcode.com/problems/inorder-successor-in-bst "二叉搜索树中的中序后继")
-
-<p>Given a binary search tree and a node in it, find the in-order successor of that node in the BST.</p>
-
-<p>The successor of a node&nbsp;<code>p</code>&nbsp;is the node with the smallest key greater than&nbsp;<code>p.val</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/23/285_example_1.PNG" style="width: 122px; height: 117px;" />
-<pre><strong>Input: </strong>root = <span id="example-input-1-1">[2,1,3]</span>, p = <span id="example-input-1-2">1</span>
-<strong>Output: </strong><span id="example-output-1">2</span>
-<strong>Explanation: </strong>1&#39;s in-order successor node is 2. Note that both p and the return value is of TreeNode type.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/23/285_example_2.PNG" style="width: 246px; height: 229px;" />
-<pre><strong>Input: </strong>root = <span id="example-input-2-1">[5,3,6,2,4,null,null,1]</span>, p = <span id="example-input-2-2">6</span>
-<strong>Output: </strong><span id="example-output-2">null</span>
-<strong>Explanation: </strong>There is no in-order successor of the current node, so the answer is <code>null</code>.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>If the given node has no in-order successor in the tree, return <code>null</code>.</li>
-	<li>It&#39;s guaranteed that the values of the tree are unique.</li>
-</ol>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Inorder Traversal](../binary-tree-inorder-traversal) (Easy)
-  1. [Binary Search Tree Iterator](../binary-search-tree-iterator) (Medium)
-  1. [Inorder Successor in BST II](../inorder-successor-in-bst-ii) (Medium)
diff --git a/problems/inorder-successor-in-bst/inorder_successor_in_bst.go b/problems/inorder-successor-in-bst/inorder_successor_in_bst.go
deleted file mode 100644
index 77cba5d0c..000000000
--- a/problems/inorder-successor-in-bst/inorder_successor_in_bst.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem285
diff --git a/problems/inorder-successor-in-bst/inorder_successor_in_bst_test.go b/problems/inorder-successor-in-bst/inorder_successor_in_bst_test.go
deleted file mode 100644
index 77cba5d0c..000000000
--- a/problems/inorder-successor-in-bst/inorder_successor_in_bst_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem285
diff --git a/problems/insert-delete-getrandom-o1-duplicates-allowed/README.md b/problems/insert-delete-getrandom-o1-duplicates-allowed/README.md
deleted file mode 100644
index 5956f4810..000000000
--- a/problems/insert-delete-getrandom-o1-duplicates-allowed/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../insert-delete-getrandom-o1 "Insert Delete GetRandom O(1)")
-　　　　　　　　　　　　　　　　
-[Next >](../linked-list-random-node "Linked List Random Node")
-
-## [381. Insert Delete GetRandom O(1) - Duplicates allowed (Hard)](https://leetcode.com/problems/insert-delete-getrandom-o1-duplicates-allowed "O(1) 时间插入、删除和获取随机元素 - 允许重复")
-
-<p>Implement the <code>RandomizedCollection</code> class:</p>
-
-<ul>
-	<li><code>RandomizedCollection()</code> Initializes the <code>RandomizedCollection</code> object.</li>
-	<li><code>bool insert(int val)</code> Inserts an item <code>val</code> into the multiset if not present. Returns <code>true</code> if the item was not present, <code>false</code> otherwise.</li>
-	<li><code>bool remove(int val)</code> Removes an item <code>val</code> from the multiset if present. Returns <code>true</code> if the item was present, <code>false</code> otherwise. Note that if <code>val</code> has multiple occurrences in the multiset, we only remove one of them.</li>
-	<li><code>int getRandom()</code> Returns a random element from the current multiset of elements (it&#39;s guaranteed that at least one element exists when this method is called). The probability of each element being returned is <strong>linearly related</strong> to the number of same values the multiset contains.</li>
-</ul>
-
-<p>You must implement the functions of the class such that each function works in&nbsp;<strong>average</strong>&nbsp;<code>O(1)</code>&nbsp;time complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;RandomizedCollection&quot;, &quot;insert&quot;, &quot;insert&quot;, &quot;insert&quot;, &quot;getRandom&quot;, &quot;remove&quot;, &quot;getRandom&quot;]
-[[], [1], [1], [2], [], [1], []]
-<strong>Output</strong>
-[null, true, false, true, 2, true, 1]
-
-<strong>Explanation</strong>
-RandomizedCollection randomizedCollection = new RandomizedCollection();
-randomizedCollection.insert(1);   // return True. Inserts 1 to the collection. Returns true as the collection did not contain 1.
-randomizedCollection.insert(1);   // return False. Inserts another 1 to the collection. Returns false as the collection contained 1. Collection now contains [1,1].
-randomizedCollection.insert(2);   // return True. Inserts 2 to the collection, returns true. Collection now contains [1,1,2].
-randomizedCollection.getRandom(); // getRandom should return 1 with the probability 2/3, and returns 2 with the probability 1/3.
-randomizedCollection.remove(1);   // return True. Removes 1 from the collection, returns true. Collection now contains [1,2].
-randomizedCollection.getRandom(); // getRandom should return 1 and 2 both equally likely.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= val &lt;= 2<sup>31</sup> - 1</code></li>
-	<li>At most <code>2 * 10<sup>5</sup></code>&nbsp; calls will be made to <code>insert</code>, <code>remove</code>, and <code>getRandom</code>.</li>
-	<li>There will be <strong>at least one</strong> element in the data structure when <code>getRandom</code> is called.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Similar Questions
-  1. [Insert Delete GetRandom O(1)](../insert-delete-getrandom-o1) (Medium)
diff --git a/problems/insert-delete-getrandom-o1-duplicates-allowed/insert_delete_getrandom_o1_duplicates_allowed.go b/problems/insert-delete-getrandom-o1-duplicates-allowed/insert_delete_getrandom_o1_duplicates_allowed.go
deleted file mode 100644
index 0c65d4048..000000000
--- a/problems/insert-delete-getrandom-o1-duplicates-allowed/insert_delete_getrandom_o1_duplicates_allowed.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem381
diff --git a/problems/insert-delete-getrandom-o1-duplicates-allowed/insert_delete_getrandom_o1_duplicates_allowed_test.go b/problems/insert-delete-getrandom-o1-duplicates-allowed/insert_delete_getrandom_o1_duplicates_allowed_test.go
deleted file mode 100644
index 0c65d4048..000000000
--- a/problems/insert-delete-getrandom-o1-duplicates-allowed/insert_delete_getrandom_o1_duplicates_allowed_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem381
diff --git a/problems/insert-delete-getrandom-o1/README.md b/problems/insert-delete-getrandom-o1/README.md
deleted file mode 100644
index 0dd514659..000000000
--- a/problems/insert-delete-getrandom-o1/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-phone-directory "Design Phone Directory")
-　　　　　　　　　　　　　　　　
-[Next >](../insert-delete-getrandom-o1-duplicates-allowed "Insert Delete GetRandom O(1) - Duplicates allowed")
-
-## [380. Insert Delete GetRandom O(1) (Medium)](https://leetcode.com/problems/insert-delete-getrandom-o1 "O(1) 时间插入、删除和获取随机元素")
-
-<p>Implement the <code>RandomizedSet</code> class:</p>
-
-<ul>
-	<li><code>RandomizedSet()</code> Initializes the <code>RandomizedSet</code> object.</li>
-	<li><code>bool insert(int val)</code> Inserts an item <code>val</code> into the set if not present. Returns <code>true</code> if the item was not present, <code>false</code> otherwise.</li>
-	<li><code>bool remove(int val)</code> Removes an item <code>val</code> from the set if present. Returns <code>true</code> if the item was present, <code>false</code> otherwise.</li>
-	<li><code>int getRandom()</code> Returns a random element from the current set of elements (it&#39;s guaranteed that at least one element exists when this method is called). Each element must have the <b>same probability</b> of being returned.</li>
-</ul>
-
-<p>You must implement the functions of the class such that each function works in&nbsp;<strong>average</strong>&nbsp;<code>O(1)</code>&nbsp;time complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;RandomizedSet&quot;, &quot;insert&quot;, &quot;remove&quot;, &quot;insert&quot;, &quot;getRandom&quot;, &quot;remove&quot;, &quot;insert&quot;, &quot;getRandom&quot;]
-[[], [1], [2], [2], [], [1], [2], []]
-<strong>Output</strong>
-[null, true, false, true, 2, true, false, 2]
-
-<strong>Explanation</strong>
-RandomizedSet randomizedSet = new RandomizedSet();
-randomizedSet.insert(1); // Inserts 1 to the set. Returns true as 1 was inserted successfully.
-randomizedSet.remove(2); // Returns false as 2 does not exist in the set.
-randomizedSet.insert(2); // Inserts 2 to the set, returns true. Set now contains [1,2].
-randomizedSet.getRandom(); // getRandom() should return either 1 or 2 randomly.
-randomizedSet.remove(1); // Removes 1 from the set, returns true. Set now contains [2].
-randomizedSet.insert(2); // 2 was already in the set, so return false.
-randomizedSet.getRandom(); // Since 2 is the only number in the set, getRandom() will always return 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= val &lt;= 2<sup>31</sup> - 1</code></li>
-	<li>At most <code>2 *&nbsp;</code><code>10<sup>5</sup></code> calls will be made to <code>insert</code>, <code>remove</code>, and <code>getRandom</code>.</li>
-	<li>There will be <strong>at least one</strong> element in the data structure when <code>getRandom</code> is called.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Similar Questions
-  1. [Insert Delete GetRandom O(1) - Duplicates allowed](../insert-delete-getrandom-o1-duplicates-allowed) (Hard)
diff --git a/problems/insert-delete-getrandom-o1/insert_delete_getrandom_o1.go b/problems/insert-delete-getrandom-o1/insert_delete_getrandom_o1.go
deleted file mode 100644
index a788df642..000000000
--- a/problems/insert-delete-getrandom-o1/insert_delete_getrandom_o1.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem380
diff --git a/problems/insert-delete-getrandom-o1/insert_delete_getrandom_o1_test.go b/problems/insert-delete-getrandom-o1/insert_delete_getrandom_o1_test.go
deleted file mode 100644
index a788df642..000000000
--- a/problems/insert-delete-getrandom-o1/insert_delete_getrandom_o1_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem380
diff --git a/problems/insert-interval/README.md b/problems/insert-interval/README.md
deleted file mode 100644
index c40a05e55..000000000
--- a/problems/insert-interval/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../merge-intervals "Merge Intervals")
-　　　　　　　　　　　　　　　　
-[Next >](../length-of-last-word "Length of Last Word")
-
-## [57. Insert Interval (Medium)](https://leetcode.com/problems/insert-interval "插入区间")
-
-<p>You are given an array of non-overlapping intervals <code>intervals</code> where <code>intervals[i] = [start<sub>i</sub>, end<sub>i</sub>]</code> represent the start and the end of the <code>i<sup>th</sup></code> interval and <code>intervals</code> is sorted in ascending order by <code>start<sub>i</sub></code>. You are also given an interval <code>newInterval = [start, end]</code> that represents the start and end of another interval.</p>
-
-<p>Insert <code>newInterval</code> into <code>intervals</code> such that <code>intervals</code> is still sorted in ascending order by <code>start<sub>i</sub></code> and <code>intervals</code> still does not have any overlapping intervals (merge overlapping intervals if necessary).</p>
-
-<p>Return <code>intervals</code><em> after the insertion</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,3],[6,9]], newInterval = [2,5]
-<strong>Output:</strong> [[1,5],[6,9]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,2],[3,5],[6,7],[8,10],[12,16]], newInterval = [4,8]
-<strong>Output:</strong> [[1,2],[3,10],[12,16]]
-<strong>Explanation:</strong> Because the new interval <code>[4,8]</code> overlaps with <code>[3,5],[6,7],[8,10]</code>.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [], newInterval = [5,7]
-<strong>Output:</strong> [[5,7]]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,5]], newInterval = [2,3]
-<strong>Output:</strong> [[1,5]]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,5]], newInterval = [2,7]
-<strong>Output:</strong> [[1,7]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= intervals.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>intervals[i].length == 2</code></li>
-	<li><code>0 &lt;= start<sub>i</sub> &lt;= end<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-	<li><code>intervals</code> is sorted by <code>start<sub>i</sub></code> in <strong>ascending</strong> order.</li>
-	<li><code>newInterval.length == 2</code></li>
-	<li><code>0 &lt;= start &lt;= end &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Merge Intervals](../merge-intervals) (Medium)
-  1. [Range Module](../range-module) (Hard)
diff --git a/problems/insert-interval/insert_interval.go b/problems/insert-interval/insert_interval.go
deleted file mode 100644
index 021f8e212..000000000
--- a/problems/insert-interval/insert_interval.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem57
diff --git a/problems/insert-interval/insert_interval_test.go b/problems/insert-interval/insert_interval_test.go
deleted file mode 100644
index 021f8e212..000000000
--- a/problems/insert-interval/insert_interval_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem57
diff --git a/problems/insert-into-a-binary-search-tree/README.md b/problems/insert-into-a-binary-search-tree/README.md
deleted file mode 100644
index c502641dd..000000000
--- a/problems/insert-into-a-binary-search-tree/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../search-in-a-binary-search-tree "Search in a Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../search-in-a-sorted-array-of-unknown-size "Search in a Sorted Array of Unknown Size")
-
-## [701. Insert into a Binary Search Tree (Medium)](https://leetcode.com/problems/insert-into-a-binary-search-tree "二叉搜索树中的插入操作")
-
-<p>You are given the <code>root</code> node of a binary search tree (BST) and a <code>value</code> to insert into the tree. Return <em>the root node of the BST after the insertion</em>. It is <strong>guaranteed</strong> that the new value does not exist in the original BST.</p>
-
-<p><strong>Notice</strong>&nbsp;that there may exist&nbsp;multiple valid ways for the&nbsp;insertion, as long as the tree remains a BST after insertion. You can return <strong>any of them</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/05/insertbst.jpg" style="width: 752px; height: 221px;" />
-<pre>
-<strong>Input:</strong> root = [4,2,7,1,3], val = 5
-<strong>Output:</strong> [4,2,7,1,3,5]
-<strong>Explanation:</strong> Another accepted tree is:
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/05/bst.jpg" style="width: 352px; height: 301px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [40,20,60,10,30,50,70], val = 25
-<strong>Output:</strong> [40,20,60,10,30,50,70,null,null,25]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [4,2,7,1,3,null,null,null,null,null,null], val = 5
-<strong>Output:</strong> [4,2,7,1,3,5]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in&nbsp;the tree will be in the range <code>[0,&nbsp;10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>8</sup> &lt;= Node.val &lt;= 10<sup>8</sup></code></li>
-	<li>All the values <code>Node.val</code> are <strong>unique</strong>.</li>
-	<li><code>-10<sup>8</sup> &lt;= val &lt;= 10<sup>8</sup></code></li>
-	<li>It&#39;s <strong>guaranteed</strong> that <code>val</code> does not exist in the original BST.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Search in a Binary Search Tree](../search-in-a-binary-search-tree) (Easy)
diff --git a/problems/insert-into-a-binary-search-tree/insert_into_a_binary_search_tree.go b/problems/insert-into-a-binary-search-tree/insert_into_a_binary_search_tree.go
deleted file mode 100644
index 31c59ae53..000000000
--- a/problems/insert-into-a-binary-search-tree/insert_into_a_binary_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem701
diff --git a/problems/insert-into-a-binary-search-tree/insert_into_a_binary_search_tree_test.go b/problems/insert-into-a-binary-search-tree/insert_into_a_binary_search_tree_test.go
deleted file mode 100644
index 31c59ae53..000000000
--- a/problems/insert-into-a-binary-search-tree/insert_into_a_binary_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem701
diff --git a/problems/insert-into-a-sorted-circular-linked-list/README.md b/problems/insert-into-a-sorted-circular-linked-list/README.md
deleted file mode 100644
index d1c4bc30b..000000000
--- a/problems/insert-into-a-sorted-circular-linked-list/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-linked-list "Design Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../to-lower-case "To Lower Case")
-
-## [708. Insert into a Sorted Circular Linked List (Medium)](https://leetcode.com/problems/insert-into-a-sorted-circular-linked-list "循环有序列表的插入")
-
-<p>Given a node from a cyclic linked list which is sorted in ascending order, write a function to insert a value into the list such that it remains a cyclic sorted list. The given node can be a reference to <em>any</em> single node in the list, and may not be necessarily the smallest value in the cyclic list.</p>
-
-<p>If there are multiple suitable places for insertion, you may choose any place to insert the new value. After the insertion, the cyclic list should remain sorted.</p>
-
-<p>If the list is empty (i.e., given node is <code>null</code>), you should create a new single cyclic list and return the reference to that single node. Otherwise, you should return the original given node.</p>
-
-<p>The following example may help you understand the problem better:</p>
-
-<p>&nbsp;</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/01/19/example_1_before_65p.jpg" style="width: 250px; height: 149px;" /><br />
-<br />
-<small>In the figure above, there is a cyclic sorted list of three elements. You are given a reference to the node with value 3, and we need to insert 2 into the list.</small></p>
-
-<p>&nbsp;</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/01/19/example_1_after_65p.jpg" style="width: 250px; height: 149px;" /><br />
-<br />
-<small>The new node should insert between node 1 and node 3. After the insertion, the list should look like this, and we should still return node 3.</small></p>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Insertion Sort List](../insertion-sort-list) (Medium)
diff --git a/problems/insertion-sort-list/README.md b/problems/insertion-sort-list/README.md
deleted file mode 100644
index 2e918925e..000000000
--- a/problems/insertion-sort-list/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lru-cache "LRU Cache")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-list "Sort List")
-
-## [147. Insertion Sort List (Medium)](https://leetcode.com/problems/insertion-sort-list "对链表进行插入排序")
-
-<p>Given the <code>head</code> of a singly linked list, sort the list using <strong>insertion sort</strong>, and return <em>the sorted list&#39;s head</em>.</p>
-
-<p>The steps of the <strong>insertion sort</strong> algorithm:</p>
-
-<ol>
-	<li>Insertion sort iterates, consuming one input element each repetition and growing a sorted output list.</li>
-	<li>At each iteration, insertion sort removes one element from the input data, finds the location it belongs within the sorted list and inserts it there.</li>
-	<li>It repeats until no input elements remain.</li>
-</ol>
-
-<p>The following is a graphical example of the insertion sort algorithm. The partially sorted list (black) initially contains only the first element in the list. One element (red) is removed from the input data and inserted in-place into the sorted list with each iteration.</p>
-<img alt="" src="https://upload.wikimedia.org/wikipedia/commons/0/0f/Insertion-sort-example-300px.gif" style="height:180px; width:300px" />
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/04/sort1linked-list.jpg" style="width: 422px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [4,2,1,3]
-<strong>Output:</strong> [1,2,3,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/04/sort2linked-list.jpg" style="width: 542px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [-1,5,3,4,0]
-<strong>Output:</strong> [-1,0,3,4,5]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[1, 5000]</code>.</li>
-	<li><code>-5000 &lt;= Node.val &lt;= 5000</code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Sort List](../sort-list) (Medium)
-  1. [Insert into a Sorted Circular Linked List](../insert-into-a-sorted-circular-linked-list) (Medium)
diff --git a/problems/insertion-sort-list/insertion_sort_list.go b/problems/insertion-sort-list/insertion_sort_list.go
deleted file mode 100644
index 7aad9cb4b..000000000
--- a/problems/insertion-sort-list/insertion_sort_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem147
diff --git a/problems/insertion-sort-list/insertion_sort_list_test.go b/problems/insertion-sort-list/insertion_sort_list_test.go
deleted file mode 100644
index 7aad9cb4b..000000000
--- a/problems/insertion-sort-list/insertion_sort_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem147
diff --git a/problems/insufficient-nodes-in-root-to-leaf-paths/README.md b/problems/insufficient-nodes-in-root-to-leaf-paths/README.md
deleted file mode 100644
index 5c7a71756..000000000
--- a/problems/insufficient-nodes-in-root-to-leaf-paths/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../letter-tile-possibilities "Letter Tile Possibilities")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-subsequence-of-distinct-characters "Smallest Subsequence of Distinct Characters")
-
-## [1080. Insufficient Nodes in Root to Leaf Paths (Medium)](https://leetcode.com/problems/insufficient-nodes-in-root-to-leaf-paths "根到叶路径上的不足节点")
-
-<p>Given the <code>root</code> of a binary tree and an integer <code>limit</code>, delete all <strong>insufficient nodes</strong> in the tree simultaneously, and return <em>the root of the resulting binary tree</em>.</p>
-
-<p>A node is <strong>insufficient</strong> if every root to <strong>leaf</strong> path intersecting this node has a sum strictly less than <code>limit</code>.</p>
-
-<p>A <strong>leaf</strong> is a node with no children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/06/05/insufficient-11.png" style="width: 500px; height: 207px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,-99,-99,7,8,9,-99,-99,12,13,-99,14], limit = 1
-<strong>Output:</strong> [1,2,3,4,null,null,7,8,9,null,14]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/06/05/insufficient-3.png" style="width: 400px; height: 274px;" />
-<pre>
-<strong>Input:</strong> root = [5,4,8,11,null,17,4,7,1,null,null,5,3], limit = 22
-<strong>Output:</strong> [5,4,8,11,null,17,4,7,null,null,null,5]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/06/11/screen-shot-2019-06-11-at-83301-pm.png" style="width: 250px; height: 199px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,-3,-5,null,4,null], limit = -1
-<strong>Output:</strong> [1,null,-3,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 5000]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= limit &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider a DFS traversal of the tree.  You can keep track of the current path sum from root to this node, and you can also use DFS to return the minimum value of any path from this node to the leaf.  This will tell you if this node is insufficient.
-</details>
diff --git a/problems/integer-break/README.md b/problems/integer-break/README.md
deleted file mode 100644
index 0975fcec2..000000000
--- a/problems/integer-break/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../power-of-four "Power of Four")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-string "Reverse String")
-
-## [343. Integer Break (Medium)](https://leetcode.com/problems/integer-break "整数拆分")
-
-<p>Given an integer <code>n</code>, break it into the sum of <code>k</code> <strong>positive integers</strong>, where <code>k &gt;= 2</code>, and maximize the product of those integers.</p>
-
-<p>Return <em>the maximum product you can get</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 2 = 1 + 1, 1 &times; 1 = 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 36
-<strong>Explanation:</strong> 10 = 3 + 3 + 4, 3 &times; 3 &times; 4 = 36.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 58</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Maximize Number of Nice Divisors](../maximize-number-of-nice-divisors) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There is a simple O(n) solution to this problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You may check the breaking results of <i>n</i> ranging from 7 to 10 to discover the regularities.
-</details>
diff --git a/problems/integer-break/integer_break.go b/problems/integer-break/integer_break.go
deleted file mode 100644
index eb9c835a6..000000000
--- a/problems/integer-break/integer_break.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem343
-
-func integerBreak(n int) int {
-	if n <= 3 {
-		return n - 1
-	}
-	ans := 1
-	for n > 4 {
-		n -= 3
-		ans *= 3
-	}
-	return ans * n
-}
diff --git a/problems/integer-break/integer_break_test.go b/problems/integer-break/integer_break_test.go
deleted file mode 100644
index 2d58ab424..000000000
--- a/problems/integer-break/integer_break_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem343
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestIntegerBreak(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   2,
-			want: 1,
-		},
-		{
-			in:   10,
-			want: 36,
-		},
-		{
-			in:   3,
-			want: 2,
-		},
-		{
-			in:   7,
-			want: 12,
-		},
-		{
-			in:   17,
-			want: 486,
-		},
-	}
-	for _, tt := range tests {
-		got := integerBreak(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/integer-replacement/README.md b/problems/integer-replacement/README.md
deleted file mode 100644
index 6e163430d..000000000
--- a/problems/integer-replacement/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rotate-function "Rotate Function")
-　　　　　　　　　　　　　　　　
-[Next >](../random-pick-index "Random Pick Index")
-
-## [397. Integer Replacement (Medium)](https://leetcode.com/problems/integer-replacement "整数替换")
-
-<p>Given a positive integer <code>n</code>,&nbsp;you can apply one of the following&nbsp;operations:</p>
-
-<ol>
-	<li>If <code>n</code> is even, replace <code>n</code> with <code>n / 2</code>.</li>
-	<li>If <code>n</code> is odd, replace <code>n</code> with either <code>n + 1</code> or <code>n - 1</code>.</li>
-</ol>
-
-<p>Return <em>the minimum number of operations needed for <code>n</code> to become <code>1</code></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 8
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 8 -&gt; 4 -&gt; 2 -&gt; 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>7 -&gt; 8 -&gt; 4 -&gt; 2 -&gt; 1
-or 7 -&gt; 6 -&gt; 3 -&gt; 2 -&gt; 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
diff --git a/problems/integer-replacement/integer_replacement.go b/problems/integer-replacement/integer_replacement.go
deleted file mode 100644
index 5cccbb753..000000000
--- a/problems/integer-replacement/integer_replacement.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem397
diff --git a/problems/integer-replacement/integer_replacement_test.go b/problems/integer-replacement/integer_replacement_test.go
deleted file mode 100644
index 5cccbb753..000000000
--- a/problems/integer-replacement/integer_replacement_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem397
diff --git a/problems/integer-to-english-words/README.md b/problems/integer-to-english-words/README.md
deleted file mode 100644
index 4bc0037c2..000000000
--- a/problems/integer-to-english-words/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../closest-binary-search-tree-value-ii "Closest Binary Search Tree Value II")
-　　　　　　　　　　　　　　　　
-[Next >](../h-index "H-Index")
-
-## [273. Integer to English Words (Hard)](https://leetcode.com/problems/integer-to-english-words "整数转换英文表示")
-
-<p>Convert a non-negative integer <code>num</code> to its English words representation.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 123
-<strong>Output:</strong> &quot;One Hundred Twenty Three&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 12345
-<strong>Output:</strong> &quot;Twelve Thousand Three Hundred Forty Five&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 1234567
-<strong>Output:</strong> &quot;One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= num &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Integer to Roman](../integer-to-roman) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Did you see a pattern in dividing the number into chunk of words? For example, 123 and 123000.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Group the number by thousands (3 digits). You can write a helper function that takes a number less than 1000 and convert just that chunk to words.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-There are many edge cases. What are some good test cases? Does your code work with input such as 0? Or 1000010? (middle chunk is zero and should not be printed out)
-</details>
diff --git a/problems/integer-to-english-words/integer_to_english_words.go b/problems/integer-to-english-words/integer_to_english_words.go
deleted file mode 100644
index 87c82e1e8..000000000
--- a/problems/integer-to-english-words/integer_to_english_words.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem273
diff --git a/problems/integer-to-english-words/integer_to_english_words_test.go b/problems/integer-to-english-words/integer_to_english_words_test.go
deleted file mode 100644
index 87c82e1e8..000000000
--- a/problems/integer-to-english-words/integer_to_english_words_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem273
diff --git a/problems/integer-to-roman/README.md b/problems/integer-to-roman/README.md
deleted file mode 100644
index e923416cd..000000000
--- a/problems/integer-to-roman/README.md
+++ /dev/null
@@ -1,90 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../container-with-most-water "Container With Most Water")
-　　　　　　　　　　　　　　　　
-[Next >](../roman-to-integer "Roman to Integer")
-
-## [12. Integer to Roman (Medium)](https://leetcode.com/problems/integer-to-roman "整数转罗马数字")
-
-<p>Roman numerals are represented by seven different symbols:&nbsp;<code>I</code>, <code>V</code>, <code>X</code>, <code>L</code>, <code>C</code>, <code>D</code> and <code>M</code>.</p>
-
-<pre>
-<strong>Symbol</strong>       <strong>Value</strong>
-I             1
-V             5
-X             10
-L             50
-C             100
-D             500
-M             1000</pre>
-
-<p>For example,&nbsp;<code>2</code> is written as <code>II</code>&nbsp;in Roman numeral, just two one&#39;s added together. <code>12</code> is written as&nbsp;<code>XII</code>, which is simply <code>X + II</code>. The number <code>27</code> is written as <code>XXVII</code>, which is <code>XX + V + II</code>.</p>
-
-<p>Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not <code>IIII</code>. Instead, the number four is written as <code>IV</code>. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as <code>IX</code>. There are six instances where subtraction is used:</p>
-
-<ul>
-	<li><code>I</code> can be placed before <code>V</code> (5) and <code>X</code> (10) to make 4 and 9.&nbsp;</li>
-	<li><code>X</code> can be placed before <code>L</code> (50) and <code>C</code> (100) to make 40 and 90.&nbsp;</li>
-	<li><code>C</code> can be placed before <code>D</code> (500) and <code>M</code> (1000) to make 400 and 900.</li>
-</ul>
-
-<p>Given an integer, convert it to a roman numeral.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 3
-<strong>Output:</strong> &quot;III&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 4
-<strong>Output:</strong> &quot;IV&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 9
-<strong>Output:</strong> &quot;IX&quot;
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 58
-<strong>Output:</strong> &quot;LVIII&quot;
-<strong>Explanation:</strong> L = 50, V = 5, III = 3.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 1994
-<strong>Output:</strong> &quot;MCMXCIV&quot;
-<strong>Explanation:</strong> M = 1000, CM = 900, XC = 90 and IV = 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num &lt;= 3999</code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Roman to Integer](../roman-to-integer) (Easy)
-  1. [Integer to English Words](../integer-to-english-words) (Hard)
diff --git a/problems/integer-to-roman/integer_to_roman.go b/problems/integer-to-roman/integer_to_roman.go
deleted file mode 100644
index d5d909e96..000000000
--- a/problems/integer-to-roman/integer_to_roman.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem12
-
-func intToRoman(num int) string {
-	base := [...]int{1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1}
-	bs := [...]string{"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"}
-	ans := ""
-	for i, b := range base {
-		for num/b > 0 {
-			ans += bs[i]
-			num -= b
-		}
-	}
-	return ans
-}
diff --git a/problems/integer-to-roman/integer_to_roman_test.go b/problems/integer-to-roman/integer_to_roman_test.go
deleted file mode 100644
index 4146e85c6..000000000
--- a/problems/integer-to-roman/integer_to_roman_test.go
+++ /dev/null
@@ -1,53 +0,0 @@
-package problem12
-
-import "testing"
-
-type testType struct {
-	in   int
-	want string
-}
-
-func TestIntToRoman(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   3,
-			want: "III",
-		},
-		{
-			in:   4,
-			want: "IV",
-		},
-		{
-			in:   9,
-			want: "IX",
-		},
-		{
-			in:   20,
-			want: "XX",
-		},
-		{
-			in:   58,
-			want: "LVIII",
-		},
-		{
-			in:   1994,
-			want: "MCMXCIV",
-		},
-		{
-			in:   11111,
-			want: "MMMMMMMMMMMCXI",
-		},
-	}
-	for _, tt := range tests {
-		got := intToRoman(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
-
-func BenchmarkIntToRoman(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		intToRoman(111111)
-	}
-}
diff --git a/problems/interleaving-string/README.md b/problems/interleaving-string/README.md
deleted file mode 100644
index 587a957bd..000000000
--- a/problems/interleaving-string/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-binary-search-trees "Unique Binary Search Trees")
-　　　　　　　　　　　　　　　　
-[Next >](../validate-binary-search-tree "Validate Binary Search Tree")
-
-## [97. Interleaving String (Medium)](https://leetcode.com/problems/interleaving-string "交错字符串")
-
-<p>Given strings <code>s1</code>, <code>s2</code>, and <code>s3</code>, find whether <code>s3</code> is formed by an <strong>interleaving</strong> of <code>s1</code> and <code>s2</code>.</p>
-
-<p>An <strong>interleaving</strong> of two strings <code>s</code> and <code>t</code> is a configuration where they are divided into <strong>non-empty</strong> substrings such that:</p>
-
-<ul>
-	<li><code>s = s<sub>1</sub> + s<sub>2</sub> + ... + s<sub>n</sub></code></li>
-	<li><code>t = t<sub>1</sub> + t<sub>2</sub> + ... + t<sub>m</sub></code></li>
-	<li><code>|n - m| &lt;= 1</code></li>
-	<li>The <strong>interleaving</strong> is <code>s<sub>1</sub> + t<sub>1</sub> + s<sub>2</sub> + t<sub>2</sub> + s<sub>3</sub> + t<sub>3</sub> + ...</code> or <code>t<sub>1</sub> + s<sub>1</sub> + t<sub>2</sub> + s<sub>2</sub> + t<sub>3</sub> + s<sub>3</sub> + ...</code></li>
-</ul>
-
-<p><strong>Note:</strong> <code>a + b</code> is the concatenation of strings <code>a</code> and <code>b</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/02/interleave.jpg" style="width: 561px; height: 203px;" />
-<pre>
-<strong>Input:</strong> s1 = &quot;aabcc&quot;, s2 = &quot;dbbca&quot;, s3 = &quot;aadbbcbcac&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;aabcc&quot;, s2 = &quot;dbbca&quot;, s3 = &quot;aadbbbaccc&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;&quot;, s2 = &quot;&quot;, s3 = &quot;&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s1.length, s2.length &lt;= 100</code></li>
-	<li><code>0 &lt;= s3.length &lt;= 200</code></li>
-	<li><code>s1</code>, <code>s2</code>, and <code>s3</code> consist of lowercase English letters.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you solve it using only <code>O(s2.length)</code> additional memory space?</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/interleaving-string/interleaving_string.go b/problems/interleaving-string/interleaving_string.go
deleted file mode 100644
index 939cee37e..000000000
--- a/problems/interleaving-string/interleaving_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem97
diff --git a/problems/interleaving-string/interleaving_string_test.go b/problems/interleaving-string/interleaving_string_test.go
deleted file mode 100644
index 939cee37e..000000000
--- a/problems/interleaving-string/interleaving_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem97
diff --git a/problems/intersection-of-three-sorted-arrays/README.md b/problems/intersection-of-three-sorted-arrays/README.md
deleted file mode 100644
index 4c336af5d..000000000
--- a/problems/intersection-of-three-sorted-arrays/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../team-scores-in-football-tournament "Team Scores in Football Tournament")
-　　　　　　　　　　　　　　　　
-[Next >](../two-sum-bsts "Two Sum BSTs")
-
-## [1213. Intersection of Three Sorted Arrays (Easy)](https://leetcode.com/problems/intersection-of-three-sorted-arrays "三个有序数组的交集")
-
-<p>Given three integer arrays <code>arr1</code>, <code>arr2</code> and <code>arr3</code>&nbsp;<strong>sorted</strong> in <strong>strictly increasing</strong> order, return a sorted array of <strong>only</strong>&nbsp;the&nbsp;integers that appeared in <strong>all</strong> three arrays.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [1,2,3,4,5], arr2 = [1,2,5,7,9], arr3 = [1,3,4,5,8]
-<strong>Output:</strong> [1,5]
-<strong>Explanation: </strong>Only 1 and 5 appeared in the three arrays.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr1.length, arr2.length, arr3.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= arr1[i], arr2[i], arr3[i] &lt;= 2000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Intersection of Two Arrays](../intersection-of-two-arrays) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the frequency of all elements in the three arrays.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The elements that appeared in all the arrays would have a frequency of 3.
-</details>
diff --git a/problems/intersection-of-two-arrays-ii/README.md b/problems/intersection-of-two-arrays-ii/README.md
deleted file mode 100644
index d20f01b10..000000000
--- a/problems/intersection-of-two-arrays-ii/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../intersection-of-two-arrays "Intersection of Two Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../android-unlock-patterns "Android Unlock Patterns")
-
-## [350. Intersection of Two Arrays II (Easy)](https://leetcode.com/problems/intersection-of-two-arrays-ii "两个数组的交集 II")
-
-<p>Given two integer arrays <code>nums1</code> and <code>nums2</code>, return <em>an array of their intersection</em>. Each element in the result must appear as many times as it shows in both arrays and you may return the result in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2,2,1], nums2 = [2,2]
-<strong>Output:</strong> [2,2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [4,9,5], nums2 = [9,4,9,8,4]
-<strong>Output:</strong> [4,9]
-<strong>Explanation:</strong> [9,4] is also accepted.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums1[i], nums2[i] &lt;= 1000</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>What if the given array is already sorted? How would you optimize your algorithm?</li>
-	<li>What if <code>nums1</code>&#39;s size is small compared to <code>nums2</code>&#39;s size? Which algorithm is better?</li>
-	<li>What if elements of <code>nums2</code> are stored on disk, and the memory is limited such that you cannot load all elements into the memory at once?</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Intersection of Two Arrays](../intersection-of-two-arrays) (Easy)
-  1. [Find Common Characters](../find-common-characters) (Easy)
diff --git a/problems/intersection-of-two-arrays-ii/intersection_of_two_arrays_ii.go b/problems/intersection-of-two-arrays-ii/intersection_of_two_arrays_ii.go
deleted file mode 100644
index 0717afeae..000000000
--- a/problems/intersection-of-two-arrays-ii/intersection_of_two_arrays_ii.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem350
-
-func intersect(nums1 []int, nums2 []int) []int {
-	res := make([]int, 0, len(nums1))
-	nc := make(map[int]int)
-	for _, n := range nums2 {
-		nc[n]++
-	}
-	for _, n := range nums1 {
-		if nc[n] > 0 {
-			res = append(res, n)
-			nc[n]--
-		}
-	}
-	return res
-}
diff --git a/problems/intersection-of-two-arrays-ii/intersection_of_two_arrays_ii_test.go b/problems/intersection-of-two-arrays-ii/intersection_of_two_arrays_ii_test.go
deleted file mode 100644
index 09e52d7a1..000000000
--- a/problems/intersection-of-two-arrays-ii/intersection_of_two_arrays_ii_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem350
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	nums1 []int
-	nums2 []int
-	want  []int
-}
-
-func TestIntersect(t *testing.T) {
-	tests := [...]testType{
-		{
-			nums1: []int{1, 2, 2, 1},
-			nums2: []int{2, 2},
-			want:  []int{2, 2},
-		},
-		{
-			nums1: []int{4, 9, 5},
-			nums2: []int{9, 4, 9, 8, 4},
-			want:  []int{4, 9},
-		},
-		{
-			nums1: []int{1, 3, 3, 5, 5, 5, 7, 7, 7, 9},
-			nums2: []int{2, 3, 3, 5, 5, 5, 7, 8},
-			want:  []int{3, 3, 5, 5, 5, 7},
-		},
-	}
-	for _, tt := range tests {
-		got := intersect(tt.nums1, tt.nums2)
-		if !kit.IsEqualSliceInt(got, tt.want) {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.nums1, tt.nums2, got, tt.want)
-		}
-	}
-}
diff --git a/problems/intersection-of-two-arrays/README.md b/problems/intersection-of-two-arrays/README.md
deleted file mode 100644
index a18b5bb08..000000000
--- a/problems/intersection-of-two-arrays/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-tic-tac-toe "Design Tic-Tac-Toe")
-　　　　　　　　　　　　　　　　
-[Next >](../intersection-of-two-arrays-ii "Intersection of Two Arrays II")
-
-## [349. Intersection of Two Arrays (Easy)](https://leetcode.com/problems/intersection-of-two-arrays "两个数组的交集")
-
-<p>Given two integer arrays <code>nums1</code> and <code>nums2</code>, return <em>an array of their intersection</em>. Each element in the result must be <strong>unique</strong> and you may return the result in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2,2,1], nums2 = [2,2]
-<strong>Output:</strong> [2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [4,9,5], nums2 = [9,4,9,8,4]
-<strong>Output:</strong> [9,4]
-<strong>Explanation:</strong> [4,9] is also accepted.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums1[i], nums2[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Intersection of Two Arrays II](../intersection-of-two-arrays-ii) (Easy)
-  1. [Intersection of Three Sorted Arrays](../intersection-of-three-sorted-arrays) (Easy)
diff --git a/problems/intersection-of-two-arrays/intersection_of_two_arrays.go b/problems/intersection-of-two-arrays/intersection_of_two_arrays.go
deleted file mode 100644
index 5daf2f65c..000000000
--- a/problems/intersection-of-two-arrays/intersection_of_two_arrays.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem349
diff --git a/problems/intersection-of-two-arrays/intersection_of_two_arrays_test.go b/problems/intersection-of-two-arrays/intersection_of_two_arrays_test.go
deleted file mode 100644
index 5daf2f65c..000000000
--- a/problems/intersection-of-two-arrays/intersection_of_two_arrays_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem349
diff --git a/problems/intersection-of-two-linked-lists/README.md b/problems/intersection-of-two-linked-lists/README.md
deleted file mode 100644
index 94fff5675..000000000
--- a/problems/intersection-of-two-linked-lists/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-substring-with-at-most-two-distinct-characters "Longest Substring with At Most Two Distinct Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../one-edit-distance "One Edit Distance")
-
-## [160. Intersection of Two Linked Lists (Easy)](https://leetcode.com/problems/intersection-of-two-linked-lists "相交链表")
-
-<p>Given the heads of two singly linked-lists <code>headA</code> and <code>headB</code>, return <em>the node at which the two lists intersect</em>. If the two linked lists have no intersection at all, return <code>null</code>.</p>
-
-<p>For example, the following two linked lists begin to intersect at node <code>c1</code>:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/05/160_statement.png" style="width: 500px; height: 162px;" />
-<p>The test cases are generated such that there are no cycles anywhere in the entire linked structure.</p>
-
-<p><strong>Note</strong> that the linked lists must <strong>retain their original structure</strong> after the function returns.</p>
-
-<p><strong>Custom Judge:</strong></p>
-
-<p>The inputs to the <strong>judge</strong> are given as follows (your program is <strong>not</strong> given these inputs):</p>
-
-<ul>
-	<li><code>intersectVal</code> - The value of the node where the intersection occurs. This is <code>0</code> if there is no intersected node.</li>
-	<li><code>listA</code> - The first linked list.</li>
-	<li><code>listB</code> - The second linked list.</li>
-	<li><code>skipA</code> - The number of nodes to skip ahead in <code>listA</code> (starting from the head) to get to the intersected node.</li>
-	<li><code>skipB</code> - The number of nodes to skip ahead in <code>listB</code> (starting from the head) to get to the intersected node.</li>
-</ul>
-
-<p>The judge will then create the linked structure based on these inputs and pass the two heads, <code>headA</code> and <code>headB</code>&nbsp;to your program. If you correctly return the intersected node, then your solution will be <strong>accepted</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/05/160_example_1_1.png" style="width: 500px; height: 162px;" />
-<pre>
-<strong>Input:</strong> intersectVal = 8, listA = [4,1,8,4,5], listB = [5,6,1,8,4,5], skipA = 2, skipB = 3
-<strong>Output:</strong> Intersected at &#39;8&#39;
-<strong>Explanation:</strong> The intersected node&#39;s value is 8 (note that this must not be 0 if the two lists intersect).
-From the head of A, it reads as [4,1,8,4,5]. From the head of B, it reads as [5,6,1,8,4,5]. There are 2 nodes before the intersected node in A; There are 3 nodes before the intersected node in B.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/05/160_example_2.png" style="width: 500px; height: 194px;" />
-<pre>
-<strong>Input:</strong> intersectVal = 2, listA = [1,9,1,2,4], listB = [3,2,4], skipA = 3, skipB = 1
-<strong>Output:</strong> Intersected at &#39;2&#39;
-<strong>Explanation:</strong> The intersected node&#39;s value is 2 (note that this must not be 0 if the two lists intersect).
-From the head of A, it reads as [1,9,1,2,4]. From the head of B, it reads as [3,2,4]. There are 3 nodes before the intersected node in A; There are 1 node before the intersected node in B.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/05/160_example_3.png" style="width: 300px; height: 189px;" />
-<pre>
-<strong>Input:</strong> intersectVal = 0, listA = [2,6,4], listB = [1,5], skipA = 3, skipB = 2
-<strong>Output:</strong> No intersection
-<strong>Explanation:</strong> From the head of A, it reads as [2,6,4]. From the head of B, it reads as [1,5]. Since the two lists do not intersect, intersectVal must be 0, while skipA and skipB can be arbitrary values.
-Explanation: The two lists do not intersect, so return null.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes of <code>listA</code> is in the <code>m</code>.</li>
-	<li>The number of nodes of <code>listB</code> is in the <code>n</code>.</li>
-	<li><code>0 &lt;= m, n &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= skipA &lt;= m</code></li>
-	<li><code>0 &lt;= skipB &lt;= n</code></li>
-	<li><code>intersectVal</code> is <code>0</code> if <code>listA</code> and <code>listB</code> do not intersect.</li>
-	<li><code>intersectVal == listA[skipA] == listB[skipB]</code> if <code>listA</code> and <code>listB</code> intersect.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you write a solution that runs in <code>O(n)</code> time and use only <code>O(1)</code> memory?
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Minimum Index Sum of Two Lists](../minimum-index-sum-of-two-lists) (Easy)
diff --git a/problems/intersection-of-two-linked-lists/intersection_of_two_linked_lists.go b/problems/intersection-of-two-linked-lists/intersection_of_two_linked_lists.go
deleted file mode 100644
index eb7ef2aba..000000000
--- a/problems/intersection-of-two-linked-lists/intersection_of_two_linked_lists.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem160
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func getIntersectionNode(headA, headB *ListNode) *ListNode {
-	pA, pB := headA, headB
-	for pA != pB {
-		if pA == nil {
-			pA = headB
-		} else {
-			pA = pA.Next
-		}
-		if pB == nil {
-			pB = headA
-		} else {
-			pB = pB.Next
-		}
-	}
-	return pA
-}
diff --git a/problems/intersection-of-two-linked-lists/intersection_of_two_linked_lists_test.go b/problems/intersection-of-two-linked-lists/intersection_of_two_linked_lists_test.go
deleted file mode 100644
index b1f4b2d5b..000000000
--- a/problems/intersection-of-two-linked-lists/intersection_of_two_linked_lists_test.go
+++ /dev/null
@@ -1,59 +0,0 @@
-package problem160
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	headA        []int
-	headB        []int
-	intersection []int
-}
-
-func TestGetIntersectionNode(t *testing.T) {
-	tests := [...]testType{
-		{
-			headA:        []int{4, 1},
-			headB:        []int{5, 0, 1},
-			intersection: []int{8, 4, 5},
-		},
-		{
-			headA:        []int{0, 9, 1, 2},
-			headB:        []int{3},
-			intersection: []int{2, 4},
-		},
-		{
-			headA:        []int{2, 4, 6},
-			headB:        []int{1, 5},
-			intersection: []int{},
-		},
-		{
-			headA:        []int{1},
-			headB:        []int{},
-			intersection: []int{},
-		},
-	}
-	for _, tt := range tests {
-		intersection := kit.SliceInt2ListNode(tt.intersection)
-		headA := kit.SliceInt2ListNode(tt.headA)
-		headB := kit.SliceInt2ListNode(tt.headB)
-		for n := headA; n != nil; n = n.Next {
-			if n.Next == nil {
-				n.Next = intersection
-				break
-			}
-		}
-		for n := headB; n != nil; n = n.Next {
-			if n.Next == nil {
-				n.Next = intersection
-				break
-			}
-		}
-		got := getIntersectionNode(headA, headB)
-		if got != intersection {
-			t.Fatalf("in: %v, got: %v %v, want: %v", tt.headA, tt.headB, got, tt.intersection)
-		}
-	}
-}
diff --git a/problems/interval-list-intersections/README.md b/problems/interval-list-intersections/README.md
deleted file mode 100644
index b7251fd39..000000000
--- a/problems/interval-list-intersections/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-even-numbers-after-queries "Sum of Even Numbers After Queries")
-　　　　　　　　　　　　　　　　
-[Next >](../vertical-order-traversal-of-a-binary-tree "Vertical Order Traversal of a Binary Tree")
-
-## [986. Interval List Intersections (Medium)](https://leetcode.com/problems/interval-list-intersections "区间列表的交集")
-
-<p>You are given two lists of closed intervals, <code>firstList</code> and <code>secondList</code>, where <code>firstList[i] = [start<sub>i</sub>, end<sub>i</sub>]</code> and <code>secondList[j] = [start<sub>j</sub>, end<sub>j</sub>]</code>. Each list of intervals is pairwise <strong>disjoint</strong> and in <strong>sorted order</strong>.</p>
-
-<p>Return <em>the intersection of these two interval lists</em>.</p>
-
-<p>A <strong>closed interval</strong> <code>[a, b]</code> (with <code>a &lt;= b</code>) denotes the set of real numbers <code>x</code> with <code>a &lt;= x &lt;= b</code>.</p>
-
-<p>The <strong>intersection</strong> of two closed intervals is a set of real numbers that are either empty or represented as a closed interval. For example, the intersection of <code>[1, 3]</code> and <code>[2, 4]</code> is <code>[2, 3]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/30/interval1.png" style="width: 700px; height: 194px;" />
-<pre>
-<strong>Input:</strong> firstList = [[0,2],[5,10],[13,23],[24,25]], secondList = [[1,5],[8,12],[15,24],[25,26]]
-<strong>Output:</strong> [[1,2],[5,5],[8,10],[15,23],[24,24],[25,25]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> firstList = [[1,3],[5,9]], secondList = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> firstList = [], secondList = [[4,8],[10,12]]
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> firstList = [[1,7]], secondList = [[3,10]]
-<strong>Output:</strong> [[3,7]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= firstList.length, secondList.length &lt;= 1000</code></li>
-	<li><code>firstList.length + secondList.length &gt;= 1</code></li>
-	<li><code>0 &lt;= start<sub>i</sub> &lt; end<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>end<sub>i</sub> &lt; start<sub>i+1</sub></code></li>
-	<li><code>0 &lt;= start<sub>j</sub> &lt; end<sub>j</sub> &lt;= 10<sup>9</sup> </code></li>
-	<li><code>end<sub>j</sub> &lt; start<sub>j+1</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Merge Intervals](../merge-intervals) (Medium)
-  1. [Merge Sorted Array](../merge-sorted-array) (Easy)
-  1. [Employee Free Time](../employee-free-time) (Hard)
diff --git a/problems/interval-list-intersections/interval_list_intersections.go b/problems/interval-list-intersections/interval_list_intersections.go
deleted file mode 100644
index 48d65b265..000000000
--- a/problems/interval-list-intersections/interval_list_intersections.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem986
diff --git a/problems/intervals-between-identical-elements/README.md b/problems/intervals-between-identical-elements/README.md
deleted file mode 100644
index 8b689aeac..000000000
--- a/problems/intervals-between-identical-elements/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../execution-of-all-suffix-instructions-staying-in-a-grid "Execution of All Suffix Instructions Staying in a Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../recover-the-original-array "Recover the Original Array")
-
-## [2121. Intervals Between Identical Elements (Medium)](https://leetcode.com/problems/intervals-between-identical-elements "相同元素的间隔之和")
-
-<p>You are given a <strong>0-indexed</strong> array of <code>n</code> integers <code>arr</code>.</p>
-
-<p>The <strong>interval</strong> between two elements in <code>arr</code> is defined as the <strong>absolute difference</strong> between their indices. More formally, the <strong>interval</strong> between <code>arr[i]</code> and <code>arr[j]</code> is <code>|i - j|</code>.</p>
-
-<p>Return <em>an array</em> <code>intervals</code> <em>of length</em> <code>n</code> <em>where</em> <code>intervals[i]</code> <em>is <strong>the sum of intervals</strong> between </em><code>arr[i]</code><em> and each element in </em><code>arr</code><em> with the same value as </em><code>arr[i]</code><em>.</em></p>
-
-<p><strong>Note:</strong> <code>|x|</code> is the absolute value of <code>x</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,1,3,1,2,3,3]
-<strong>Output:</strong> [4,2,7,2,4,4,5]
-<strong>Explanation:</strong>
-- Index 0: Another 2 is found at index 4. |0 - 4| = 4
-- Index 1: Another 1 is found at index 3. |1 - 3| = 2
-- Index 2: Two more 3s are found at indices 5 and 6. |2 - 5| + |2 - 6| = 7
-- Index 3: Another 1 is found at index 1. |3 - 1| = 2
-- Index 4: Another 2 is found at index 0. |4 - 0| = 4
-- Index 5: Two more 3s are found at indices 2 and 6. |5 - 2| + |5 - 6| = 4
-- Index 6: Two more 3s are found at indices 2 and 5. |6 - 2| + |6 - 5| = 5
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [10,5,10,10]
-<strong>Output:</strong> [5,0,3,4]
-<strong>Explanation:</strong>
-- Index 0: Two more 10s are found at indices 2 and 3. |0 - 2| + |0 - 3| = 5
-- Index 1: There is only one 5 in the array, so its sum of intervals to identical elements is 0.
-- Index 2: Two more 10s are found at indices 0 and 3. |2 - 0| + |2 - 3| = 3
-- Index 3: Two more 10s are found at indices 0 and 2. |3 - 0| + |3 - 2| = 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == arr.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each unique value found in the array, store a sorted list of indices of elements that have this value in the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-One way of doing this is to use a HashMap that maps the values to their list of indices. Update this mapping as you iterate through the array.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Process each list of indices separately and get the sum of intervals for the elements of that value by utilizing prefix sums.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For each element, keep track of the sum of indices of the identical elements that have come before and that will come after respectively. Use this to calculate the sum of intervals for that element to the rest of the elements with identical values.
-</details>
diff --git a/problems/invalid-transactions/README.md b/problems/invalid-transactions/README.md
deleted file mode 100644
index f8165e7ad..000000000
--- a/problems/invalid-transactions/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../optimize-water-distribution-in-a-village "Optimize Water Distribution in a Village")
-　　　　　　　　　　　　　　　　
-[Next >](../compare-strings-by-frequency-of-the-smallest-character "Compare Strings by Frequency of the Smallest Character")
-
-## [1169. Invalid Transactions (Medium)](https://leetcode.com/problems/invalid-transactions "查询无效交易")
-
-<p>A transaction is possibly invalid if:</p>
-
-<ul>
-	<li>the amount exceeds <code>$1000</code>, or;</li>
-	<li>if it occurs within (and including) <code>60</code> minutes of another transaction with the <strong>same name</strong> in a <strong>different city</strong>.</li>
-</ul>
-
-<p>You are given an array of strings <code>transaction</code> where <code>transactions[i]</code> consists of comma-separated values representing the name, time (in minutes), amount, and city of the transaction.</p>
-
-<p>Return a list of <code>transactions</code> that are possibly invalid. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> transactions = [&quot;alice,20,800,mtv&quot;,&quot;alice,50,100,beijing&quot;]
-<strong>Output:</strong> [&quot;alice,20,800,mtv&quot;,&quot;alice,50,100,beijing&quot;]
-<strong>Explanation:</strong> The first transaction is invalid because the second transaction occurs within a difference of 60 minutes, have the same name and is in a different city. Similarly the second one is invalid too.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> transactions = [&quot;alice,20,800,mtv&quot;,&quot;alice,50,1200,mtv&quot;]
-<strong>Output:</strong> [&quot;alice,50,1200,mtv&quot;]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> transactions = [&quot;alice,20,800,mtv&quot;,&quot;bob,50,1200,mtv&quot;]
-<strong>Output:</strong> [&quot;bob,50,1200,mtv&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>transactions.length &lt;= 1000</code></li>
-	<li>Each <code>transactions[i]</code> takes the form <code>&quot;{name},{time},{amount},{city}&quot;</code></li>
-	<li>Each <code>{name}</code> and <code>{city}</code> consist of lowercase English letters, and have lengths between <code>1</code> and <code>10</code>.</li>
-	<li>Each <code>{time}</code> consist of digits, and represent an integer between <code>0</code> and <code>1000</code>.</li>
-	<li>Each <code>{amount}</code> consist of digits, and represent an integer between <code>0</code> and <code>2000</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Split each string into four arrays.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each transaction check if it's invalid, you can do this with just a loop with help of the four arrays generated on step 1.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-At the end you perform O(N ^ 2) operations.
-</details>
diff --git a/problems/invalid-tweets/README.md b/problems/invalid-tweets/README.md
deleted file mode 100644
index 2c9eab577..000000000
--- a/problems/invalid-tweets/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-palindromic-subsequence-ii "Longest Palindromic Subsequence II")
-　　　　　　　　　　　　　　　　
-[Next >](../count-the-number-of-consistent-strings "Count the Number of Consistent Strings")
-
-## [1683. Invalid Tweets (Easy)](https://leetcode.com/problems/invalid-tweets "无效的推文")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/invalid-tweets/mysql_schemas.sql b/problems/invalid-tweets/mysql_schemas.sql
deleted file mode 100644
index f3839daf1..000000000
--- a/problems/invalid-tweets/mysql_schemas.sql
+++ /dev/null
@@ -1,4 +0,0 @@
-Create table If Not Exists Tweets(tweet_id int, content varchar(50));
-Truncate table Tweets;
-insert into Tweets (tweet_id, content) values ('1', 'Vote for Biden');
-insert into Tweets (tweet_id, content) values ('2', 'Let us make America great again!');
diff --git a/problems/invert-binary-tree/README.md b/problems/invert-binary-tree/README.md
deleted file mode 100644
index 3f0f28c55..000000000
--- a/problems/invert-binary-tree/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../implement-stack-using-queues "Implement Stack using Queues")
-　　　　　　　　　　　　　　　　
-[Next >](../basic-calculator-ii "Basic Calculator II")
-
-## [226. Invert Binary Tree (Easy)](https://leetcode.com/problems/invert-binary-tree "翻转二叉树")
-
-<p>Given the <code>root</code> of a binary tree, invert the tree, and return <em>its root</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/14/invert1-tree.jpg" style="width: 500px; height: 165px;" />
-<pre>
-<strong>Input:</strong> root = [4,2,7,1,3,6,9]
-<strong>Output:</strong> [4,7,2,9,6,3,1]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/14/invert2-tree.jpg" style="width: 500px; height: 120px;" />
-<pre>
-<strong>Input:</strong> root = [2,1,3]
-<strong>Output:</strong> [2,3,1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 100]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/invert-binary-tree/invert_binary_tree.go b/problems/invert-binary-tree/invert_binary_tree.go
deleted file mode 100644
index ae7bccdf6..000000000
--- a/problems/invert-binary-tree/invert_binary_tree.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem226
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func invertTree(root *TreeNode) *TreeNode {
-	if root != nil {
-		root.Left, root.Right = root.Right, root.Left
-		invertTree(root.Left)
-		invertTree(root.Right)
-	}
-	return root
-}
diff --git a/problems/invert-binary-tree/invert_binary_tree_test.go b/problems/invert-binary-tree/invert_binary_tree_test.go
deleted file mode 100644
index 7a6a30719..000000000
--- a/problems/invert-binary-tree/invert_binary_tree_test.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem226
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestInvertTree(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{4, 2, 7, 1, 3, 6, 9},
-			want: []int{4, 7, 2, 9, 6, 3, 1},
-		},
-	}
-	for _, tt := range tests {
-		out := invertTree(kit.SliceInt2TreeNode(tt.in))
-		got := kit.TreeNode2SliceInt(out)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/investments-in-2016/README.md b/problems/investments-in-2016/README.md
deleted file mode 100644
index 0d88b615d..000000000
--- a/problems/investments-in-2016/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-customer-referee "Find Customer Referee")
-　　　　　　　　　　　　　　　　
-[Next >](../customer-placing-the-largest-number-of-orders "Customer Placing the Largest Number of Orders")
-
-## [585. Investments in 2016 (Medium)](https://leetcode.com/problems/investments-in-2016 "2016年的投资")
-
-<p>Write a query to print the sum of all total investment values in 2016 (<b>TIV_2016</b>), to a scale of 2 decimal places, for all policy holders who meet the following criteria:</p>
-
-<ol>
-	<li>Have the same <b>TIV_2015</b> value as one or more other policyholders.</li>
-	<li>Are not located in the same city as any other policyholder (i.e.: the (latitude, longitude) attribute pairs must be unique).</li>
-</ol>
-
-<p><b>Input Format:</b><br />
-The <b><i>insurance</i></b> table is described as follows:</p>
-
-<pre>
-| Column Name | Type          |
-|-------------|---------------|
-| PID         | INTEGER(11)   |
-| TIV_2015    | NUMERIC(15,2) |
-| TIV_2016    | NUMERIC(15,2) |
-| LAT         | NUMERIC(5,2)  |
-| LON         | NUMERIC(5,2)  |
-</pre>
-
-<p>where <b>PID</b> is the policyholder&#39;s policy ID, <b>TIV_2015</b> is the total investment value in 2015, <b>TIV_2016</b> is the total investment value in 2016, <b>LAT</b> is the latitude of the policy holder&#39;s city, and <b>LON</b> is the longitude of the policy holder&#39;s city.</p>
-
-<p><b>Sample Input</b></p>
-
-<pre>
-| PID | TIV_2015 | TIV_2016 | LAT | LON |
-|-----|----------|----------|-----|-----|
-| 1   | 10       | 5        | 10  | 10  |
-| 2   | 20       | 20       | 20  | 20  |
-| 3   | 10       | 30       | 20  | 20  |
-| 4   | 10       | 40       | 40  | 40  |
-</pre>
-
-<p><b>Sample Output</b></p>
-
-<pre>
-| TIV_2016 |
-|----------|
-| 45.00    |
-</pre>
-
-<p><b>Explanation</b></p>
-
-<pre>
-The first record in the table, like the last record, meets both of the two criteria.
-The <b>TIV_2015</b> value &#39;10&#39; is as the same as the third and forth record, and its location unique.
-
-The second record does not meet any of the two criteria. Its <b>TIV_2015</b> is not like any other policyholders.
-
-And its location is the same with the third record, which makes the third record fail, too.
-
-So, the result is the sum of <b>TIV_2016</b> of the first and last record, which is 45.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Make the (LAT, LON) a pair to represent the location information
-</details>
diff --git a/problems/investments-in-2016/investments_in_2016.sql b/problems/investments-in-2016/investments_in_2016.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/investments-in-2016/investments_in_2016.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/investments-in-2016/mysql_schemas.sql b/problems/investments-in-2016/mysql_schemas.sql
deleted file mode 100644
index 7541fd98a..000000000
--- a/problems/investments-in-2016/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create Table If Not Exists Insurance (pid int, tiv_2015 float, tiv_2016 float, lat float, lon float);
-Truncate table Insurance;
-insert into Insurance (pid, tiv_2015, tiv_2016, lat, lon) values ('1', '10', '5', '10', '10');
-insert into Insurance (pid, tiv_2015, tiv_2016, lat, lon) values ('2', '20', '20', '20', '20');
-insert into Insurance (pid, tiv_2015, tiv_2016, lat, lon) values ('3', '10', '30', '20', '20');
-insert into Insurance (pid, tiv_2015, tiv_2016, lat, lon) values ('4', '10', '40', '40', '40');
diff --git a/problems/ip-to-cidr/README.md b/problems/ip-to-cidr/README.md
deleted file mode 100644
index be63e0887..000000000
--- a/problems/ip-to-cidr/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-corner-rectangles "Number Of Corner Rectangles")
-　　　　　　　　　　　　　　　　
-[Next >](../open-the-lock "Open the Lock")
-
-## [751. IP to CIDR (Medium)](https://leetcode.com/problems/ip-to-cidr "IP 到 CIDR")
-
-<p>
-Given a start IP address <code>ip</code> and a number of ips we need to cover <code>n</code>, return a representation of the range as a list (of smallest possible length) of CIDR blocks.
-</p><p>
-A CIDR block is a string consisting of an IP, followed by a slash, and then the prefix length.  For example: "123.45.67.89/20".  That prefix length "20" represents the number of common prefix bits in the specified range.
-</p>
-
-<p><b>Example 1:</b><br />
-<pre>
-<b>Input:</b> ip = "255.0.0.7", n = 10
-<b>Output:</b> ["255.0.0.7/32","255.0.0.8/29","255.0.0.16/32"]
-<b>Explanation:</b>
-The initial ip address, when converted to binary, looks like this (spaces added for clarity):
-255.0.0.7 -> 11111111 00000000 00000000 00000111
-The address "255.0.0.7/32" specifies all addresses with a common prefix of 32 bits to the given address,
-ie. just this one address.
-
-The address "255.0.0.8/29" specifies all addresses with a common prefix of 29 bits to the given address:
-255.0.0.8 -> 11111111 00000000 00000000 00001000
-Addresses with common prefix of 29 bits are:
-11111111 00000000 00000000 00001000
-11111111 00000000 00000000 00001001
-11111111 00000000 00000000 00001010
-11111111 00000000 00000000 00001011
-11111111 00000000 00000000 00001100
-11111111 00000000 00000000 00001101
-11111111 00000000 00000000 00001110
-11111111 00000000 00000000 00001111
-
-The address "255.0.0.16/32" specifies all addresses with a common prefix of 32 bits to the given address,
-ie. just 11111111 00000000 00000000 00010000.
-
-In total, the answer specifies the range of 10 ips starting with the address 255.0.0.7 .
-
-There were other representations, such as:
-["255.0.0.7/32","255.0.0.8/30", "255.0.0.12/30", "255.0.0.16/32"],
-but our answer was the shortest possible.
-
-Also note that a representation beginning with say, "255.0.0.7/30" would be incorrect,
-because it includes addresses like 255.0.0.4 = 11111111 00000000 00000000 00000100 
-that are outside the specified range.
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li><code>ip</code> will be a valid IPv4 address.</li>
-<li>Every implied address <code>ip + x</code> (for <code>x < n</code>) will be a valid IPv4 address.</li>
-<li><code>n</code> will be an integer in the range <code>[1, 1000]</code>.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Restore IP Addresses](../restore-ip-addresses) (Medium)
-  1. [Validate IP Address](../validate-ip-address) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert the ip addresses to and from (long) integers.  You want to know what is the most addresses you can put in this block starting from the "start" ip, up to n.  It is the smallest between the lowest bit of start and the highest bit of n.  Then, repeat this process with a new start and n.
-</details>
diff --git a/problems/ip-to-cidr/ip_to_cidr.go b/problems/ip-to-cidr/ip_to_cidr.go
deleted file mode 100644
index 7e87b7abf..000000000
--- a/problems/ip-to-cidr/ip_to_cidr.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem751
diff --git a/problems/ip-to-cidr/ip_to_cidr_test.go b/problems/ip-to-cidr/ip_to_cidr_test.go
deleted file mode 100644
index 7e87b7abf..000000000
--- a/problems/ip-to-cidr/ip_to_cidr_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem751
diff --git a/problems/ipo/README.md b/problems/ipo/README.md
deleted file mode 100644
index 902487817..000000000
--- a/problems/ipo/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-mode-in-binary-search-tree "Find Mode in Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../next-greater-element-ii "Next Greater Element II")
-
-## [502. IPO (Hard)](https://leetcode.com/problems/ipo "IPO")
-
-<p>Suppose LeetCode will start its <strong>IPO</strong> soon. In order to sell a good price of its shares to Venture Capital, LeetCode would like to work on some projects to increase its capital before the <strong>IPO</strong>. Since it has limited resources, it can only finish at most <code>k</code> distinct projects before the <strong>IPO</strong>. Help LeetCode design the best way to maximize its total capital after finishing at most <code>k</code> distinct projects.</p>
-
-<p>You are given <code>n</code> projects where the <code>i<sup>th</sup></code> project has a pure profit <code>profits[i]</code> and a minimum capital of <code>capital[i]</code> is needed to start it.</p>
-
-<p>Initially, you have <code>w</code> capital. When you finish a project, you will obtain its pure profit and the profit will be added to your total capital.</p>
-
-<p>Pick a list of <strong>at most</strong> <code>k</code> distinct projects from given projects to <strong>maximize your final capital</strong>, and return <em>the final maximized capital</em>.</p>
-
-<p>The answer is guaranteed to fit in a 32-bit signed integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 2, w = 0, profits = [1,2,3], capital = [0,1,1]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Since your initial capital is 0, you can only start the project indexed 0.
-After finishing it you will obtain profit 1 and your capital becomes 1.
-With capital 1, you can either start the project indexed 1 or the project indexed 2.
-Since you can choose at most 2 projects, you need to finish the project indexed 2 to get the maximum capital.
-Therefore, output the final maximized capital, which is 0 + 1 + 3 = 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3, w = 0, profits = [1,2,3], capital = [0,1,2]
-<strong>Output:</strong> 6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= w &lt;= 10<sup>9</sup></code></li>
-	<li><code>n == profits.length</code></li>
-	<li><code>n == capital.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= profits[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= capital[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
diff --git a/problems/ipo/ipo.go b/problems/ipo/ipo.go
deleted file mode 100644
index 84e5a9542..000000000
--- a/problems/ipo/ipo.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem502
diff --git a/problems/ipo/ipo_test.go b/problems/ipo/ipo_test.go
deleted file mode 100644
index 84e5a9542..000000000
--- a/problems/ipo/ipo_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem502
diff --git a/problems/is-graph-bipartite/README.md b/problems/is-graph-bipartite/README.md
deleted file mode 100644
index fa8efd94f..000000000
--- a/problems/is-graph-bipartite/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../letter-case-permutation "Letter Case Permutation")
-　　　　　　　　　　　　　　　　
-[Next >](../k-th-smallest-prime-fraction "K-th Smallest Prime Fraction")
-
-## [785. Is Graph Bipartite? (Medium)](https://leetcode.com/problems/is-graph-bipartite "判断二分图")
-
-<p>There is an <strong>undirected</strong> graph with <code>n</code> nodes, where each node is numbered between <code>0</code> and <code>n - 1</code>. You are given a 2D array <code>graph</code>, where <code>graph[u]</code> is an array of nodes that node <code>u</code> is adjacent to. More formally, for each <code>v</code> in <code>graph[u]</code>, there is an undirected edge between node <code>u</code> and node <code>v</code>. The graph has the following properties:</p>
-
-<ul>
-	<li>There are no self-edges (<code>graph[u]</code> does not contain <code>u</code>).</li>
-	<li>There are no parallel edges (<code>graph[u]</code> does not contain duplicate values).</li>
-	<li>If <code>v</code> is in <code>graph[u]</code>, then <code>u</code> is in <code>graph[v]</code> (the graph is undirected).</li>
-	<li>The graph may not be connected, meaning there may be two nodes <code>u</code> and <code>v</code> such that there is no path between them.</li>
-</ul>
-
-<p>A graph is <strong>bipartite</strong> if the nodes can be partitioned into two independent sets <code>A</code> and <code>B</code> such that <strong>every</strong> edge in the graph connects a node in set <code>A</code> and a node in set <code>B</code>.</p>
-
-<p>Return <code>true</code><em> if and only if it is <strong>bipartite</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/21/bi2.jpg" style="width: 222px; height: 222px;" />
-<pre>
-<strong>Input:</strong> graph = [[1,2,3],[0,2],[0,1,3],[0,2]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There is no way to partition the nodes into two independent sets such that every edge connects a node in one and a node in the other.</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/21/bi1.jpg" style="width: 222px; height: 222px;" />
-<pre>
-<strong>Input:</strong> graph = [[1,3],[0,2],[1,3],[0,2]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We can partition the nodes into two sets: {0, 2} and {1, 3}.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>graph.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>0 &lt;= graph[u].length &lt; n</code></li>
-	<li><code>0 &lt;= graph[u][i] &lt;= n - 1</code></li>
-	<li><code>graph[u]</code>&nbsp;does not contain&nbsp;<code>u</code>.</li>
-	<li>All the values of <code>graph[u]</code> are <strong>unique</strong>.</li>
-	<li>If <code>graph[u]</code> contains <code>v</code>, then <code>graph[v]</code> contains <code>u</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
diff --git a/problems/is-graph-bipartite/is_graph_bipartite.go b/problems/is-graph-bipartite/is_graph_bipartite.go
deleted file mode 100644
index 91647f00d..000000000
--- a/problems/is-graph-bipartite/is_graph_bipartite.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem785
diff --git a/problems/is-graph-bipartite/is_graph_bipartite_test.go b/problems/is-graph-bipartite/is_graph_bipartite_test.go
deleted file mode 100644
index 91647f00d..000000000
--- a/problems/is-graph-bipartite/is_graph_bipartite_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem785
diff --git a/problems/is-subsequence/README.md b/problems/is-subsequence/README.md
deleted file mode 100644
index a57e77471..000000000
--- a/problems/is-subsequence/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../perfect-rectangle "Perfect Rectangle")
-　　　　　　　　　　　　　　　　
-[Next >](../utf-8-validation "UTF-8 Validation")
-
-## [392. Is Subsequence (Easy)](https://leetcode.com/problems/is-subsequence "判断子序列")
-
-<p>Given two strings <code>s</code> and <code>t</code>, return <code>true</code><em> if </em><code>s</code><em> is a <strong>subsequence</strong> of </em><code>t</code><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>A <strong>subsequence</strong> of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e., <code>&quot;ace&quot;</code> is a subsequence of <code>&quot;<u>a</u>b<u>c</u>d<u>e</u>&quot;</code> while <code>&quot;aec&quot;</code> is not).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "abc", t = "ahbgdc"
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "axc", t = "ahbgdc"
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length &lt;= 100</code></li>
-	<li><code>0 &lt;= t.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> and <code>t</code> consist only of lowercase English letters.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Suppose there are lots of incoming <code>s</code>, say <code>s<sub>1</sub>, s<sub>2</sub>, ..., s<sub>k</sub></code> where <code>k &gt;= 10<sup>9</sup></code>, and you want to check one by one to see if <code>t</code> has its subsequence. In this scenario, how would you change your code?
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Number of Matching Subsequences](../number-of-matching-subsequences) (Medium)
-  1. [Shortest Way to Form String](../shortest-way-to-form-string) (Medium)
diff --git a/problems/is-subsequence/is_subsequence.go b/problems/is-subsequence/is_subsequence.go
deleted file mode 100644
index 27d18f7cf..000000000
--- a/problems/is-subsequence/is_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem392
diff --git a/problems/is-subsequence/is_subsequence_test.go b/problems/is-subsequence/is_subsequence_test.go
deleted file mode 100644
index 27d18f7cf..000000000
--- a/problems/is-subsequence/is_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem392
diff --git a/problems/island-perimeter/README.md b/problems/island-perimeter/README.md
deleted file mode 100644
index 4bf38e2a2..000000000
--- a/problems/island-perimeter/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-moves-to-equal-array-elements-ii "Minimum Moves to Equal Array Elements II")
-　　　　　　　　　　　　　　　　
-[Next >](../can-i-win "Can I Win")
-
-## [463. Island Perimeter (Easy)](https://leetcode.com/problems/island-perimeter "岛屿的周长")
-
-<p>You are given <code>row x col</code> <code>grid</code> representing a map where <code>grid[i][j] = 1</code> represents&nbsp;land and <code>grid[i][j] = 0</code> represents water.</p>
-
-<p>Grid cells are connected <strong>horizontally/vertically</strong> (not diagonally). The <code>grid</code> is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells).</p>
-
-<p>The island doesn&#39;t have &quot;lakes&quot;, meaning the water inside isn&#39;t connected to the water around the island. One cell is a square with side length 1. The grid is rectangular, width and height don&#39;t exceed 100. Determine the perimeter of the island.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://assets.leetcode.com/uploads/2018/10/12/island.png" style="width: 221px; height: 213px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1,0,0],[1,1,1,0],[0,1,0,0],[1,1,0,0]]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> The perimeter is the 16 yellow stripes in the image above.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1]]
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,0]]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>row == grid.length</code></li>
-	<li><code>col == grid[i].length</code></li>
-	<li><code>1 &lt;= row, col &lt;= 100</code></li>
-	<li><code>grid[i][j]</code> is <code>0</code> or <code>1</code>.</li>
-	<li>There is exactly one island in <code>grid</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Max Area of Island](../max-area-of-island) (Medium)
-  1. [Flood Fill](../flood-fill) (Easy)
-  1. [Coloring A Border](../coloring-a-border) (Medium)
diff --git a/problems/island-perimeter/island_perimeter.go b/problems/island-perimeter/island_perimeter.go
deleted file mode 100644
index 6ca7aac6b..000000000
--- a/problems/island-perimeter/island_perimeter.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem463
diff --git a/problems/island-perimeter/island_perimeter_test.go b/problems/island-perimeter/island_perimeter_test.go
deleted file mode 100644
index 6ca7aac6b..000000000
--- a/problems/island-perimeter/island_perimeter_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem463
diff --git a/problems/isomorphic-strings/README.md b/problems/isomorphic-strings/README.md
deleted file mode 100644
index db81a33c6..000000000
--- a/problems/isomorphic-strings/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-primes "Count Primes")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-linked-list "Reverse Linked List")
-
-## [205. Isomorphic Strings (Easy)](https://leetcode.com/problems/isomorphic-strings "同构字符串")
-
-<p>Given two strings <code>s</code> and <code>t</code>, <em>determine if they are isomorphic</em>.</p>
-
-<p>Two strings <code>s</code> and <code>t</code> are isomorphic if the characters in <code>s</code> can be replaced to get <code>t</code>.</p>
-
-<p>All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character, but a character may map to itself.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "egg", t = "add"
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "foo", t = "bar"
-<strong>Output:</strong> false
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s = "paper", t = "title"
-<strong>Output:</strong> true
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>t.length == s.length</code></li>
-	<li><code>s</code> and <code>t</code> consist of any valid ascii character.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Word Pattern](../word-pattern) (Easy)
diff --git a/problems/isomorphic-strings/isomorphic_strings.go b/problems/isomorphic-strings/isomorphic_strings.go
deleted file mode 100644
index 3dccd4793..000000000
--- a/problems/isomorphic-strings/isomorphic_strings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem205
diff --git a/problems/isomorphic-strings/isomorphic_strings_test.go b/problems/isomorphic-strings/isomorphic_strings_test.go
deleted file mode 100644
index 3dccd4793..000000000
--- a/problems/isomorphic-strings/isomorphic_strings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem205
diff --git a/problems/iterator-for-combination/README.md b/problems/iterator-for-combination/README.md
deleted file mode 100644
index 193a09a29..000000000
--- a/problems/iterator-for-combination/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-start-and-end-number-of-continuous-ranges "Find the Start and End Number of Continuous Ranges")
-　　　　　　　　　　　　　　　　
-[Next >](../element-appearing-more-than-25-in-sorted-array "Element Appearing More Than 25% In Sorted Array")
-
-## [1286. Iterator for Combination (Medium)](https://leetcode.com/problems/iterator-for-combination "字母组合迭代器")
-
-<p>Design the <code>CombinationIterator</code> class:</p>
-
-<ul>
-	<li><code>CombinationIterator(string characters, int combinationLength)</code> Initializes the object with a string <code>characters</code> of <strong>sorted distinct</strong> lowercase English letters and a number <code>combinationLength</code> as arguments.</li>
-	<li><code>next()</code> Returns the next combination of length <code>combinationLength</code> in <strong>lexicographical order</strong>.</li>
-	<li><code>hasNext()</code> Returns <code>true</code> if and only if there exists a next combination.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;CombinationIterator&quot;, &quot;next&quot;, &quot;hasNext&quot;, &quot;next&quot;, &quot;hasNext&quot;, &quot;next&quot;, &quot;hasNext&quot;]
-[[&quot;abc&quot;, 2], [], [], [], [], [], []]
-<strong>Output</strong>
-[null, &quot;ab&quot;, true, &quot;ac&quot;, true, &quot;bc&quot;, false]
-
-<strong>Explanation</strong>
-CombinationIterator itr = new CombinationIterator(&quot;abc&quot;, 2);
-itr.next();    // return &quot;ab&quot;
-itr.hasNext(); // return True
-itr.next();    // return &quot;ac&quot;
-itr.hasNext(); // return True
-itr.next();    // return &quot;bc&quot;
-itr.hasNext(); // return False
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= combinationLength &lt;= characters.length &lt;= 15</code></li>
-	<li>All the characters of <code>characters</code> are <strong>unique</strong>.</li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>next</code> and <code>hasNext</code>.</li>
-	<li>It is guaranteed that all calls of the function <code>next</code> are valid.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Iterator](../../tag/iterator/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Generate all combinations as a preprocessing.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use bit masking to generate all the combinations.
-</details>
diff --git a/problems/jewels-and-stones/README.md b/problems/jewels-and-stones/README.md
deleted file mode 100644
index 03f1ca5a9..000000000
--- a/problems/jewels-and-stones/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../basic-calculator-iv "Basic Calculator IV")
-　　　　　　　　　　　　　　　　
-[Next >](../basic-calculator-iii "Basic Calculator III")
-
-## [771. Jewels and Stones (Easy)](https://leetcode.com/problems/jewels-and-stones "宝石与石头")
-
-<p>You&#39;re given strings <code>jewels</code> representing the types of stones that are jewels, and <code>stones</code> representing the stones you have. Each character in <code>stones</code> is a type of stone you have. You want to know how many of the stones you have are also jewels.</p>
-
-<p>Letters are case sensitive, so <code>&quot;a&quot;</code> is considered a different type of stone from <code>&quot;A&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> jewels = "aA", stones = "aAAbbbb"
-<strong>Output:</strong> 3
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> jewels = "z", stones = "ZZ"
-<strong>Output:</strong> 0
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;jewels.length, stones.length &lt;= 50</code></li>
-	<li><code>jewels</code> and <code>stones</code> consist of only English letters.</li>
-	<li>All the characters of&nbsp;<code>jewels</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each stone, check if it is a jewel.
-</details>
diff --git a/problems/jewels-and-stones/jewels_and_stones.go b/problems/jewels-and-stones/jewels_and_stones.go
deleted file mode 100644
index 2607b8877..000000000
--- a/problems/jewels-and-stones/jewels_and_stones.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem771
-
-func numJewelsInStones(J string, S string) int {
-	m := [128]bool{}
-	for i := 0; i < len(J); i++ {
-		m[J[i]] = true
-	}
-	count := 0
-	for i := 0; i < len(S); i++ {
-		if m[S[i]] {
-			count++
-		}
-	}
-	return count
-}
diff --git a/problems/jewels-and-stones/jewels_and_stones_test.go b/problems/jewels-and-stones/jewels_and_stones_test.go
deleted file mode 100644
index 9d172224f..000000000
--- a/problems/jewels-and-stones/jewels_and_stones_test.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package problem771
-
-import "testing"
-
-type testType struct {
-	j    string
-	s    string
-	want int
-}
-
-func TestNumJewelsInStones(t *testing.T) {
-	tests := [...]testType{
-		{
-			j:    "aA",
-			s:    "aAAbbbb",
-			want: 3,
-		},
-		{
-			j:    "z",
-			s:    "ZZ",
-			want: 0,
-		},
-		{
-			j:    "Tb",
-			s:    "abcdefhelloaabads",
-			want: 2,
-		},
-	}
-
-	for _, tt := range tests {
-		got := numJewelsInStones(tt.j, tt.s)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.j, tt.s, got, tt.want)
-		}
-	}
-}
diff --git a/problems/jump-game-ii/README.md b/problems/jump-game-ii/README.md
deleted file mode 100644
index 986e4cccd..000000000
--- a/problems/jump-game-ii/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../wildcard-matching "Wildcard Matching")
-　　　　　　　　　　　　　　　　
-[Next >](../permutations "Permutations")
-
-## [45. Jump Game II (Medium)](https://leetcode.com/problems/jump-game-ii "跳跃游戏 II")
-
-<p>Given an array of non-negative integers <code>nums</code>, you are initially positioned at the first index of the array.</p>
-
-<p>Each element in the array represents your maximum jump length at that position.</p>
-
-<p>Your goal is to reach the last index in the minimum number of jumps.</p>
-
-<p>You can assume that you can always reach the last index.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,1,1,4]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The minimum number of jumps to reach the last index is 2. Jump 1 step from index 0 to 1, then 3 steps to the last index.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,0,1,4]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Jump Game](../jump-game) (Medium)
-  1. [Jump Game III](../jump-game-iii) (Medium)
-  1. [Jump Game VII](../jump-game-vii) (Medium)
diff --git a/problems/jump-game-ii/jump_game_ii.go b/problems/jump-game-ii/jump_game_ii.go
deleted file mode 100644
index a326b299c..000000000
--- a/problems/jump-game-ii/jump_game_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem45
diff --git a/problems/jump-game-ii/jump_game_ii_test.go b/problems/jump-game-ii/jump_game_ii_test.go
deleted file mode 100644
index a326b299c..000000000
--- a/problems/jump-game-ii/jump_game_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem45
diff --git a/problems/jump-game-iii/README.md b/problems/jump-game-iii/README.md
deleted file mode 100644
index 876cb75b2..000000000
--- a/problems/jump-game-iii/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-elements-in-two-binary-search-trees "All Elements in Two Binary Search Trees")
-　　　　　　　　　　　　　　　　
-[Next >](../verbal-arithmetic-puzzle "Verbal Arithmetic Puzzle")
-
-## [1306. Jump Game III (Medium)](https://leetcode.com/problems/jump-game-iii "跳跃游戏 III")
-
-<p>Given an array of non-negative integers <code>arr</code>, you are initially positioned at <code>start</code>&nbsp;index of the array. When you are at index <code>i</code>, you can jump&nbsp;to <code>i + arr[i]</code> or <code>i - arr[i]</code>, check if you can reach to <strong>any</strong> index with value 0.</p>
-
-<p>Notice that you can not jump outside of the array at any time.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,2,3,0,3,1,2], start = 5
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 
-All possible ways to reach at index 3 with value 0 are: 
-index 5 -&gt; index 4 -&gt; index 1 -&gt; index 3 
-index 5 -&gt; index 6 -&gt; index 4 -&gt; index 1 -&gt; index 3 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,2,3,0,3,1,2], start = 0
-<strong>Output:</strong> true 
-<strong>Explanation: 
-</strong>One possible way to reach at index 3 with value 0 is: 
-index 0 -&gt; index 4 -&gt; index 1 -&gt; index 3
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,0,2,1,2], start = 2
-<strong>Output:</strong> false
-<strong>Explanation: </strong>There is no way to reach at index 1 with value 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= arr[i] &lt;&nbsp;arr.length</code></li>
-	<li><code>0 &lt;= start &lt; arr.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Jump Game II](../jump-game-ii) (Medium)
-  1. [Jump Game](../jump-game) (Medium)
-  1. [Jump Game VII](../jump-game-vii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think of BFS to solve the problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When you reach a position with a value = 0 then return true.
-</details>
diff --git a/problems/jump-game-iv/README.md b/problems/jump-game-iv/README.md
deleted file mode 100644
index 3c3ba13a3..000000000
--- a/problems/jump-game-iv/README.md
+++ /dev/null
@@ -1,92 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../angle-between-hands-of-a-clock "Angle Between Hands of a Clock")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-n-and-its-double-exist "Check If N and Its Double Exist")
-
-## [1345. Jump Game IV (Hard)](https://leetcode.com/problems/jump-game-iv "跳跃游戏 IV")
-
-<p>Given an array of&nbsp;integers <code>arr</code>, you are initially positioned at the first index of the array.</p>
-
-<p>In one step you can jump from index <code>i</code> to index:</p>
-
-<ul>
-	<li><code>i + 1</code> where:&nbsp;<code>i + 1 &lt; arr.length</code>.</li>
-	<li><code>i - 1</code> where:&nbsp;<code>i - 1 &gt;= 0</code>.</li>
-	<li><code>j</code> where: <code>arr[i] == arr[j]</code> and <code>i != j</code>.</li>
-</ul>
-
-<p>Return <em>the minimum number of steps</em> to reach the <strong>last index</strong> of the array.</p>
-
-<p>Notice that you can not jump outside of the array at any time.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [100,-23,-23,404,100,23,23,23,3,404]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You need three jumps from index 0 --&gt; 4 --&gt; 3 --&gt; 9. Note that index 9 is the last index of the array.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [7]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Start index is the last index. You don&#39;t need to jump.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [7,6,9,6,9,6,9,7]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You can jump directly from index 0 to index 7 which is last index of the array.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [6,1,9]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [11,22,7,7,7,7,7,7,7,22,13]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>-10<sup>8</sup> &lt;= arr[i] &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Jump Game VII](../jump-game-vii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build a graph of n nodes where nodes are the indices of the array and edges for node i are nodes i+1, i-1, j where arr[i] == arr[j].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Start bfs from node 0 and keep distance, answer is the distance when you reach onode n-1.
-</details>
diff --git a/problems/jump-game-v/README.md b/problems/jump-game-v/README.md
deleted file mode 100644
index 5c5e3730c..000000000
--- a/problems/jump-game-v/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-product-of-splitted-binary-tree "Maximum Product of Splitted Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../movie-rating "Movie Rating")
-
-## [1340. Jump Game V (Hard)](https://leetcode.com/problems/jump-game-v "跳跃游戏 V")
-
-<p>Given an array of&nbsp;integers <code>arr</code> and an integer <code>d</code>. In one step you can jump from index <code>i</code> to index:</p>
-
-<ul>
-	<li><code>i + x</code> where:&nbsp;<code>i + x &lt; arr.length</code> and <code> 0 &lt;&nbsp;x &lt;= d</code>.</li>
-	<li><code>i - x</code> where:&nbsp;<code>i - x &gt;= 0</code> and <code> 0 &lt;&nbsp;x &lt;= d</code>.</li>
-</ul>
-
-<p>In addition, you can only jump from index <code>i</code> to index <code>j</code>&nbsp;if <code>arr[i] &gt; arr[j]</code> and <code>arr[i] &gt; arr[k]</code> for all indices <code>k</code> between <code>i</code> and <code>j</code> (More formally <code>min(i,&nbsp;j) &lt; k &lt; max(i, j)</code>).</p>
-
-<p>You can choose any index of the array and start jumping. Return <em>the maximum number of indices</em>&nbsp;you can visit.</p>
-
-<p>Notice that you can not jump outside of the array at any time.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/23/meta-chart.jpeg" style="width: 633px; height: 419px;" />
-<pre>
-<strong>Input:</strong> arr = [6,4,14,6,8,13,9,7,10,6,12], d = 2
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> You can start at index 10. You can jump 10 --&gt; 8 --&gt; 6 --&gt; 7 as shown.
-Note that if you start at index 6 you can only jump to index 7. You cannot jump to index 5 because 13 &gt; 9. You cannot jump to index 4 because index 5 is between index 4 and 6 and 13 &gt; 9.
-Similarly You cannot jump from index 3 to index 2 or index 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,3,3,3,3], d = 3
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You can start at any index. You always cannot jump to any index.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [7,6,5,4,3,2,1], d = 1
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> Start at index 0. You can visit all the indicies. 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= d &lt;= arr.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming. dp[i] is max jumps you can do starting from index i. Answer is max(dp[i]).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-dp[i] = 1 + max (dp[j]) where j is all indices you can reach from i.
-</details>
diff --git a/problems/jump-game-vi/README.md b/problems/jump-game-vi/README.md
deleted file mode 100644
index 80cd600af..000000000
--- a/problems/jump-game-vi/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-erasure-value "Maximum Erasure Value")
-　　　　　　　　　　　　　　　　
-[Next >](../checking-existence-of-edge-length-limited-paths "Checking Existence of Edge Length Limited Paths")
-
-## [1696. Jump Game VI (Medium)](https://leetcode.com/problems/jump-game-vi "跳跃游戏 VI")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code> and an integer <code>k</code>.</p>
-
-<p>You are initially standing at index <code>0</code>. In one move, you can jump at most <code>k</code> steps forward without going outside the boundaries of the array. That is, you can jump from index <code>i</code> to any index in the range <code>[i + 1, min(n - 1, i + k)]</code> <strong>inclusive</strong>.</p>
-
-<p>You want to reach the last index of the array (index <code>n - 1</code>). Your <strong>score</strong> is the <strong>sum</strong> of all <code>nums[j]</code> for each index <code>j</code> you visited in the array.</p>
-
-<p>Return <em>the <strong>maximum score</strong> you can get</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [<u>1</u>,<u>-1</u>,-2,<u>4</u>,-7,<u>3</u>], k = 2
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> You can choose your jumps forming the subsequence [1,-1,4,3] (underlined above). The sum is 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [<u>10</u>,-5,-2,<u>4</u>,0,<u>3</u>], k = 3
-<strong>Output:</strong> 17
-<strong>Explanation:</strong> You can choose your jumps forming the subsequence [10,4,3] (underlined above). The sum is 17.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,-5,-20,4,-1,3,-6,-3], k = 2
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length, k &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Monotonic Queue](../../tag/monotonic-queue/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let dp[i] be "the maximum score to reach the end starting at index i". The answer for dp[i] is nums[i] + max{dp[i+j]} for 1 <= j <= k. That gives an O(n*k) solution.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Instead of checking every j for every i, keep track of the largest dp[i] values in a heap and calculate dp[i] from right to left. When the largest value in the heap is out of bounds of the current index, remove it and keep checking.
-</details>
diff --git a/problems/jump-game-vii/README.md b/problems/jump-game-vii/README.md
deleted file mode 100644
index b8df8c8f6..000000000
--- a/problems/jump-game-vii/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-speed-to-arrive-on-time "Minimum Speed to Arrive on Time")
-　　　　　　　　　　　　　　　　
-[Next >](../stone-game-viii "Stone Game VIII")
-
-## [1871. Jump Game VII (Medium)](https://leetcode.com/problems/jump-game-vii "跳跃游戏 VII")
-
-<p>You are given a <strong>0-indexed</strong> binary string <code>s</code> and two integers <code>minJump</code> and <code>maxJump</code>. In the beginning, you are standing at index <code>0</code>, which is equal to <code>&#39;0&#39;</code>. You can move from index <code>i</code> to index <code>j</code> if the following conditions are fulfilled:</p>
-
-<ul>
-	<li><code>i + minJump &lt;= j &lt;= min(i + maxJump, s.length - 1)</code>, and</li>
-	<li><code>s[j] == &#39;0&#39;</code>.</li>
-</ul>
-
-<p>Return <code>true</code><i> if you can reach index </i><code>s.length - 1</code><i> in </i><code>s</code><em>, or </em><code>false</code><em> otherwise.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;<u>0</u>11<u>0</u>1<u>0</u>&quot;, minJump = 2, maxJump = 3
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-In the first step, move from index 0 to index 3. 
-In the second step, move from index 3 to index 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;01101110&quot;, minJump = 2, maxJump = 3
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-	<li><code>s[0] == &#39;0&#39;</code></li>
-	<li><code>1 &lt;= minJump &lt;= maxJump &lt; s.length</code></li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider for each reachable index i the interval [i + a, i + b].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use partial sums to mark the intervals as reachable.
-</details>
diff --git a/problems/jump-game/README.md b/problems/jump-game/README.md
deleted file mode 100644
index 161f004dd..000000000
--- a/problems/jump-game/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../spiral-matrix "Spiral Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../merge-intervals "Merge Intervals")
-
-## [55. Jump Game (Medium)](https://leetcode.com/problems/jump-game "跳跃游戏")
-
-<p>You are given an integer array <code>nums</code>. You are initially positioned at the array&#39;s <strong>first index</strong>, and each element in the array represents your maximum jump length at that position.</p>
-
-<p>Return <code>true</code><em> if you can reach the last index, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,1,1,4]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Jump 1 step from index 0 to 1, then 3 steps to the last index.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,1,0,4]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> You will always arrive at index 3 no matter what. Its maximum jump length is 0, which makes it impossible to reach the last index.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Jump Game II](../jump-game-ii) (Medium)
diff --git a/problems/jump-game/jump_game.go b/problems/jump-game/jump_game.go
deleted file mode 100644
index a4a099378..000000000
--- a/problems/jump-game/jump_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem55
diff --git a/problems/jump-game/jump_game_test.go b/problems/jump-game/jump_game_test.go
deleted file mode 100644
index a4a099378..000000000
--- a/problems/jump-game/jump_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem55
diff --git a/problems/k-closest-points-to-origin/README.md b/problems/k-closest-points-to-origin/README.md
deleted file mode 100644
index f9d20533a..000000000
--- a/problems/k-closest-points-to-origin/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../equal-rational-numbers "Equal Rational Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../subarray-sums-divisible-by-k "Subarray Sums Divisible by K")
-
-## [973. K Closest Points to Origin (Medium)](https://leetcode.com/problems/k-closest-points-to-origin "最接近原点的 K 个点")
-
-<p>Given an array of <code>points</code> where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> represents a point on the <strong>X-Y</strong> plane and an integer <code>k</code>, return the <code>k</code> closest points to the origin <code>(0, 0)</code>.</p>
-
-<p>The distance between two points on the <strong>X-Y</strong> plane is the Euclidean distance (i.e., <code>&radic;(x<sub>1</sub> - x<sub>2</sub>)<sup>2</sup> + (y<sub>1</sub> - y<sub>2</sub>)<sup>2</sup></code>).</p>
-
-<p>You may return the answer in <strong>any order</strong>. The answer is <strong>guaranteed</strong> to be <strong>unique</strong> (except for the order that it is in).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/03/closestplane1.jpg" style="width: 400px; height: 400px;" />
-<pre>
-<strong>Input:</strong> points = [[1,3],[-2,2]], k = 1
-<strong>Output:</strong> [[-2,2]]
-<strong>Explanation:</strong>
-The distance between (1, 3) and the origin is sqrt(10).
-The distance between (-2, 2) and the origin is sqrt(8).
-Since sqrt(8) &lt; sqrt(10), (-2, 2) is closer to the origin.
-We only want the closest k = 1 points from the origin, so the answer is just [[-2,2]].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[3,3],[5,-1],[-2,4]], k = 2
-<strong>Output:</strong> [[3,3],[-2,4]]
-<strong>Explanation:</strong> The answer [[-2,4],[3,3]] would also be accepted.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= points.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt; x<sub>i</sub>, y<sub>i</sub> &lt; 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Quickselect](../../tag/quickselect/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Kth Largest Element in an Array](../kth-largest-element-in-an-array) (Medium)
-  1. [Top K Frequent Elements](../top-k-frequent-elements) (Medium)
-  1. [Top K Frequent Words](../top-k-frequent-words) (Medium)
diff --git a/problems/k-closest-points-to-origin/k_closest_points_to_origin.go b/problems/k-closest-points-to-origin/k_closest_points_to_origin.go
deleted file mode 100644
index d2704f85c..000000000
--- a/problems/k-closest-points-to-origin/k_closest_points_to_origin.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem973
-
-import "sort"
-
-func kClosest(points [][]int, K int) [][]int {
-	sort.Slice(points, func(i, j int) bool {
-		return points[i][0]*points[i][0]+points[i][1]*points[i][1] < points[j][0]*points[j][0]+points[j][1]*points[j][1]
-	})
-	return points[:K]
-}
diff --git a/problems/k-closest-points-to-origin/k_closest_points_to_origin_test.go b/problems/k-closest-points-to-origin/k_closest_points_to_origin_test.go
deleted file mode 100644
index 3fb34c3fe..000000000
--- a/problems/k-closest-points-to-origin/k_closest_points_to_origin_test.go
+++ /dev/null
@@ -1,45 +0,0 @@
-package problem973
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   [][]int
-	k    int
-	want [][]int
-}
-
-func TestKClosest(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{1, 3},
-				{-2, 2},
-			},
-			k: 1,
-			want: [][]int{
-				{-2, 2},
-			},
-		},
-		{
-			in: [][]int{
-				{3, 3},
-				{5, -1},
-				{-2, 4},
-			},
-			k: 2,
-			want: [][]int{
-				{3, 3},
-				{-2, 4},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := kClosest(tt.in, tt.k)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/k-concatenation-maximum-sum/README.md b/problems/k-concatenation-maximum-sum/README.md
deleted file mode 100644
index bc3299b89..000000000
--- a/problems/k-concatenation-maximum-sum/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-substrings-between-each-pair-of-parentheses "Reverse Substrings Between Each Pair of Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../critical-connections-in-a-network "Critical Connections in a Network")
-
-## [1191. K-Concatenation Maximum Sum (Medium)](https://leetcode.com/problems/k-concatenation-maximum-sum "K 次串联后最大子数组之和")
-
-<p>Given an integer array <code>arr</code> and an integer <code>k</code>, modify the array by repeating it <code>k</code> times.</p>
-
-<p>For example, if <code>arr = [1, 2]</code> and <code>k = 3 </code>then the modified array will be <code>[1, 2, 1, 2, 1, 2]</code>.</p>
-
-<p>Return the maximum sub-array sum in the modified array. Note that the length of the sub-array can be <code>0</code> and its sum in that case is <code>0</code>.</p>
-
-<p>As the answer can be very large, return the answer <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2], k = 3
-<strong>Output:</strong> 9
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,-2,1], k = 5
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [-1,-2], k = 7
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= arr[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to solve the problem for k=1 ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use Kadane's algorithm for k=1.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What are the possible cases for the answer ?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The answer is the maximum between, the answer for k=1, the sum of the whole array multiplied by k, or the maximum suffix sum plus the maximum prefix sum plus (k-2) multiplied by the whole array sum for k > 1.
-</details>
diff --git a/problems/k-diff-pairs-in-an-array/README.md b/problems/k-diff-pairs-in-an-array/README.md
deleted file mode 100644
index a78983e37..000000000
--- a/problems/k-diff-pairs-in-an-array/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lonely-pixel-i "Lonely Pixel I")
-　　　　　　　　　　　　　　　　
-[Next >](../lonely-pixel-ii "Lonely Pixel II")
-
-## [532. K-diff Pairs in an Array (Medium)](https://leetcode.com/problems/k-diff-pairs-in-an-array "数组中的 k-diff 数对")
-
-<p>Given an array of integers <code>nums</code> and an integer <code>k</code>, return <em>the number of <b>unique</b> k-diff pairs in the array</em>.</p>
-
-<p>A <strong>k-diff</strong> pair is an integer pair <code>(nums[i], nums[j])</code>, where the following are true:</p>
-
-<ul>
-	<li><code>0 &lt;= i &lt; j &lt; nums.length</code></li>
-	<li><code>|nums[i] - nums[j]| == k</code></li>
-</ul>
-
-<p><strong>Notice</strong> that <code>|val|</code> denotes the absolute value of <code>val</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,4,1,5], k = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are two 2-diff pairs in the array, (1, 3) and (3, 5).
-Although we have two 1s in the input, we should only return the number of <strong>unique</strong> pairs.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5], k = 1
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are four 1-diff pairs in the array, (1, 2), (2, 3), (3, 4) and (4, 5).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,1,5,4], k = 0
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There is one 0-diff pair in the array, (1, 1).
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,4,4,3,3,0,9,2,3], k = 3
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,-2,-3], k = 1
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>7</sup> &lt;= nums[i] &lt;= 10<sup>7</sup></code></li>
-	<li><code>0 &lt;= k &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Minimum Absolute Difference in BST](../minimum-absolute-difference-in-bst) (Easy)
-  1. [Count Number of Pairs With Absolute Difference K](../count-number-of-pairs-with-absolute-difference-k) (Easy)
-  1. [Kth Smallest Product of Two Sorted Arrays](../kth-smallest-product-of-two-sorted-arrays) (Hard)
diff --git a/problems/k-diff-pairs-in-an-array/k_diff_pairs_in_an_array.go b/problems/k-diff-pairs-in-an-array/k_diff_pairs_in_an_array.go
deleted file mode 100644
index 0ba26919e..000000000
--- a/problems/k-diff-pairs-in-an-array/k_diff_pairs_in_an_array.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem532
-
-func findPairs(nums []int, k int) int {
-	ans, m := 0, make(map[int]int)
-	for _, v := range nums {
-		m[v]++
-	}
-	for n, v := range m {
-		if k < 0 {
-			return ans
-		} else if k == 0 && v >= 2 {
-			ans++
-		} else if k > 0 && m[n+k] > 0 {
-			ans++
-		}
-	}
-	return ans
-}
diff --git a/problems/k-diff-pairs-in-an-array/k_diff_pairs_in_an_array_test.go b/problems/k-diff-pairs-in-an-array/k_diff_pairs_in_an_array_test.go
deleted file mode 100644
index 6fe5b4a3a..000000000
--- a/problems/k-diff-pairs-in-an-array/k_diff_pairs_in_an_array_test.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package problem532
-
-import "testing"
-
-type testType struct {
-	nums []int
-	k    int
-	want int
-}
-
-func TestFindPairs(t *testing.T) {
-	tests := [...]testType{
-		{
-			nums: []int{1, 3, 1, 5, 4},
-			k:    0,
-			want: 1,
-		},
-		{
-			nums: []int{3, 1, 4, 1, 5},
-			k:    2,
-			want: 2,
-		},
-		{
-			nums: []int{1, 2, 3, 4, 5},
-			k:    1,
-			want: 4,
-		},
-		{
-			nums: []int{1, 2, 3, 4, 5},
-			k:    -1,
-			want: 0,
-		},
-	}
-	for _, tt := range tests {
-		got := findPairs(tt.nums, tt.k)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.nums, tt.k, got, tt.want)
-		}
-	}
-}
diff --git a/problems/k-empty-slots/README.md b/problems/k-empty-slots/README.md
deleted file mode 100644
index 52e3d2d3e..000000000
--- a/problems/k-empty-slots/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../baseball-game "Baseball Game")
-　　　　　　　　　　　　　　　　
-[Next >](../redundant-connection "Redundant Connection")
-
-## [683. K Empty Slots (Hard)](https://leetcode.com/problems/k-empty-slots "K 个关闭的灯泡")
-
-<p>You have <code>N</code> bulbs in a row numbered from <code>1</code> to <code>N</code>. Initially, all the bulbs are turned off. We turn on exactly one bulb everyday until all bulbs are on after <code>N</code> days.</p>
-
-<p>You are given an array <code>bulbs</code>&nbsp;of length <code>N</code>&nbsp;where <code>bulbs[i] = x</code> means that on the <code>(i+1)th</code> day, we will turn on the bulb at position <code>x</code>&nbsp;where&nbsp;<code>i</code>&nbsp;is&nbsp;<code>0-indexed</code>&nbsp;and&nbsp;<code>x</code>&nbsp;is&nbsp;<code>1-indexed.</code></p>
-
-<p>Given an integer <code>K</code>, find out the <strong>minimum day number</strong> such that there exists two <strong>turned on</strong> bulbs that have <strong>exactly</strong>&nbsp;<code>K</code> bulbs between them that are <strong>all turned off</strong>.</p>
-
-<p>If there isn&#39;t such day, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<b>Input:</b> 
-bulbs: [1,3,2]
-K: 1
-<b>Output:</b> 2
-<b>Explanation:</b>
-On the first day: bulbs[0] = 1, first bulb is turned on: [1,0,0]
-On the second day: bulbs[1] = 3, third bulb is turned on: [1,0,1]
-On the third day: bulbs[2] = 2, second bulb is turned on: [1,1,1]
-We return 2 because on the second day, there were two on bulbs with one off bulb between them.
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<b>Input:</b> 
-bulbs: [1,2,3]
-K: 1
-<b>Output:</b> -1
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li><code>1 &lt;= N &lt;= 20000</code></li>
-	<li><code>1 &lt;= bulbs[i] &lt;= N</code></li>
-	<li><code>bulbs</code>&nbsp;is a permutation of numbers from&nbsp;<code>1</code>&nbsp;to&nbsp;<code>N</code>.</li>
-	<li><code>0 &lt;= K &lt;= 20000</code></li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
diff --git a/problems/k-empty-slots/k_empty_slots.go b/problems/k-empty-slots/k_empty_slots.go
deleted file mode 100644
index 6f1b06a49..000000000
--- a/problems/k-empty-slots/k_empty_slots.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem683
diff --git a/problems/k-empty-slots/k_empty_slots_test.go b/problems/k-empty-slots/k_empty_slots_test.go
deleted file mode 100644
index 6f1b06a49..000000000
--- a/problems/k-empty-slots/k_empty_slots_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem683
diff --git a/problems/k-highest-ranked-items-within-a-price-range/README.md b/problems/k-highest-ranked-items-within-a-price-range/README.md
deleted file mode 100644
index 85a214e2c..000000000
--- a/problems/k-highest-ranked-items-within-a-price-range/README.md
+++ /dev/null
@@ -1,121 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-the-hidden-sequences "Count the Hidden Sequences")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-divide-a-long-corridor "Number of Ways to Divide a Long Corridor")
-
-## [2146. K Highest Ranked Items Within a Price Range (Medium)](https://leetcode.com/problems/k-highest-ranked-items-within-a-price-range "价格范围内最高排名的 K 样物品")
-
-<p>You are given a <strong>0-indexed</strong> 2D integer array <code>grid</code> of size <code>m x n</code> that represents a map of the items in a shop. The integers in the grid represent the following:</p>
-
-<ul>
-	<li><code>0</code> represents a wall that you cannot pass through.</li>
-	<li><code>1</code> represents an empty cell that you can freely move to and from.</li>
-	<li>All other positive integers represent the price of an item in that cell. You may also freely move to and from these item cells.</li>
-</ul>
-
-<p>It takes <code>1</code> step to travel between adjacent grid cells.</p>
-
-<p>You are also given integer arrays <code>pricing</code> and <code>start</code> where <code>pricing = [low, high]</code> and <code>start = [row, col]</code> indicates that you start at the position <code>(row, col)</code> and are interested only in items with a price in the range of <code>[low, high]</code> (<strong>inclusive</strong>). You are further given an integer <code>k</code>.</p>
-
-<p>You are interested in the <strong>positions</strong> of the <code>k</code> <strong>highest-ranked</strong> items whose prices are <strong>within</strong> the given price range. The rank is determined by the <strong>first</strong> of these criteria that is different:</p>
-
-<ol>
-	<li>Distance, defined as the length of the shortest path from the <code>start</code> (<strong>shorter</strong> distance has a higher rank).</li>
-	<li>Price (<strong>lower</strong> price has a higher rank, but it must be <strong>in the price range</strong>).</li>
-	<li>The row number (<strong>smaller</strong> row number has a higher rank).</li>
-	<li>The column number (<strong>smaller</strong> column number has a higher rank).</li>
-</ol>
-
-<p>Return <em>the </em><code>k</code><em> highest-ranked items within the price range <strong>sorted</strong> by their rank (highest to lowest)</em>. If there are fewer than <code>k</code> reachable items within the price range, return <em><strong>all</strong> of them</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/16/example1drawio.png" style="width: 200px; height: 151px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,2,0,1],[1,3,0,1],[0,2,5,1]], pricing = [2,5], start = [0,0], k = 3
-<strong>Output:</strong> [[0,1],[1,1],[2,1]]
-<strong>Explanation:</strong> You start at (0,0).
-With a price range of [2,5], we can take items from (0,1), (1,1), (2,1) and (2,2).
-The ranks of these items are:
-- (0,1) with distance 1
-- (1,1) with distance 2
-- (2,1) with distance 3
-- (2,2) with distance 4
-Thus, the 3 highest ranked items in the price range are (0,1), (1,1), and (2,1).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/16/example2drawio1.png" style="width: 200px; height: 151px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,2,0,1],[1,3,3,1],[0,2,5,1]], pricing = [2,3], start = [2,3], k = 2
-<strong>Output:</strong> [[2,1],[1,2]]
-<strong>Explanation:</strong> You start at (2,3).
-With a price range of [2,3], we can take items from (0,1), (1,1), (1,2) and (2,1).
-The ranks of these items are:
-- (2,1) with distance 2, price 2
-- (1,2) with distance 2, price 3
-- (1,1) with distance 3
-- (0,1) with distance 4
-Thus, the 2 highest ranked items in the price range are (2,1) and (1,2).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/30/example3.png" style="width: 149px; height: 150px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,1,1],[0,0,1],[2,3,4]], pricing = [2,3], start = [0,0], k = 3
-<strong>Output:</strong> [[2,1],[2,0]]
-<strong>Explanation:</strong> You start at (0,0).
-With a price range of [2,3], we can take items from (2,0) and (2,1). 
-The ranks of these items are: 
-- (2,1) with distance 5
-- (2,0) with distance 6
-Thus, the 2 highest ranked items in the price range are (2,1) and (2,0). 
-Note that k = 3 but there are only 2 reachable items within the price range.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= m * n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;= 10<sup>5</sup></code></li>
-	<li><code>pricing.length == 2</code></li>
-	<li><code>2 &lt;= low &lt;= high &lt;= 10<sup>5</sup></code></li>
-	<li><code>start.length == 2</code></li>
-	<li><code>0 &lt;= row &lt;= m - 1</code></li>
-	<li><code>0 &lt;= col &lt;= n - 1</code></li>
-	<li><code>grid[row][col] &gt; 0</code></li>
-	<li><code>1 &lt;= k &lt;= m * n</code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could you determine the rank of every item efficiently?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can perform a breadth-first search from the starting position and know the length of the shortest path from start to every item.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Sort all the items according to the conditions listed in the problem, and return the first k (or all if less than k exist) items as the answer.
-</details>
diff --git a/problems/k-inverse-pairs-array/README.md b/problems/k-inverse-pairs-array/README.md
deleted file mode 100644
index 965cf20b2..000000000
--- a/problems/k-inverse-pairs-array/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-product-of-three-numbers "Maximum Product of Three Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../course-schedule-iii "Course Schedule III")
-
-## [629. K Inverse Pairs Array (Hard)](https://leetcode.com/problems/k-inverse-pairs-array "K个逆序对数组")
-
-<p>For an integer array <code>nums</code>, an <strong>inverse pair</strong> is a pair of integers <code>[i, j]</code> where <code>0 &lt;= i &lt; j &lt; nums.length</code> and <code>nums[i] &gt; nums[j]</code>.</p>
-
-<p>Given two integers n and k, return the number of different arrays consist of numbers from <code>1</code> to <code>n</code> such that there are exactly <code>k</code> <strong>inverse pairs</strong>. Since the answer can be huge, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 0
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Only the array [1,2,3] which consists of numbers from 1 to 3 has exactly 0 inverse pairs.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 1
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The array [1,3,2] and [2,1,3] have exactly 1 inverse pair.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>0 &lt;= k &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/k-inverse-pairs-array/k_inverse_pairs_array.go b/problems/k-inverse-pairs-array/k_inverse_pairs_array.go
deleted file mode 100644
index 36318233e..000000000
--- a/problems/k-inverse-pairs-array/k_inverse_pairs_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem629
diff --git a/problems/k-inverse-pairs-array/k_inverse_pairs_array_test.go b/problems/k-inverse-pairs-array/k_inverse_pairs_array_test.go
deleted file mode 100644
index 36318233e..000000000
--- a/problems/k-inverse-pairs-array/k_inverse_pairs_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem629
diff --git a/problems/k-radius-subarray-averages/README.md b/problems/k-radius-subarray-averages/README.md
deleted file mode 100644
index f062f0a12..000000000
--- a/problems/k-radius-subarray-averages/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-target-indices-after-sorting-array "Find Target Indices After Sorting Array")
-　　　　　　　　　　　　　　　　
-[Next >](../removing-minimum-and-maximum-from-array "Removing Minimum and Maximum From Array")
-
-## [2090. K Radius Subarray Averages (Medium)](https://leetcode.com/problems/k-radius-subarray-averages "半径为 k 的子数组平均值")
-
-<p>You are given a <strong>0-indexed</strong> array <code>nums</code> of <code>n</code> integers, and an integer <code>k</code>.</p>
-
-<p>The <strong>k-radius average</strong> for a subarray of <code>nums</code> <strong>centered</strong> at some index <code>i</code> with the <strong>radius</strong> <code>k</code> is the average of <strong>all</strong> elements in <code>nums</code> between the indices <code>i - k</code> and <code>i + k</code> (<strong>inclusive</strong>). If there are less than <code>k</code> elements before <strong>or</strong> after the index <code>i</code>, then the <strong>k-radius average</strong> is <code>-1</code>.</p>
-
-<p>Build and return <em>an array </em><code>avgs</code><em> of length </em><code>n</code><em> where </em><code>avgs[i]</code><em> is the <strong>k-radius average</strong> for the subarray centered at index </em><code>i</code>.</p>
-
-<p>The <strong>average</strong> of <code>x</code> elements is the sum of the <code>x</code> elements divided by <code>x</code>, using <strong>integer division</strong>. The integer division truncates toward zero, which means losing its fractional part.</p>
-
-<ul>
-	<li>For example, the average of four elements <code>2</code>, <code>3</code>, <code>1</code>, and <code>5</code> is <code>(2 + 3 + 1 + 5) / 4 = 11 / 4 = 2.75</code>, which truncates to <code>2</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/07/eg1.png" style="width: 343px; height: 119px;" />
-<pre>
-<strong>Input:</strong> nums = [7,4,3,9,1,8,5,2,6], k = 3
-<strong>Output:</strong> [-1,-1,-1,5,4,4,-1,-1,-1]
-<strong>Explanation:</strong>
-- avg[0], avg[1], and avg[2] are -1 because there are less than k elements <strong>before</strong> each index.
-- The sum of the subarray centered at index 3 with radius 3 is: 7 + 4 + 3 + 9 + 1 + 8 + 5 = 37.
-  Using <strong>integer division</strong>, avg[3] = 37 / 7 = 5.
-- For the subarray centered at index 4, avg[4] = (4 + 3 + 9 + 1 + 8 + 5 + 2) / 7 = 4.
-- For the subarray centered at index 5, avg[5] = (3 + 9 + 1 + 8 + 5 + 2 + 6) / 7 = 4.
-- avg[6], avg[7], and avg[8] are -1 because there are less than k elements <strong>after</strong> each index.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [100000], k = 0
-<strong>Output:</strong> [100000]
-<strong>Explanation:</strong>
-- The sum of the subarray centered at index 0 with radius 0 is: 100000.
-  avg[0] = 100000 / 1 = 100000.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [8], k = 100000
-<strong>Output:</strong> [-1]
-<strong>Explanation:</strong> 
-- avg[0] is -1 because there are less than k elements before and after index 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i], k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-To calculate the average of a subarray, you need the sum and the K. K is already given. How could you quickly calculate the sum of a subarray?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the Prefix Sums method to calculate the subarray sums.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-It is possible that the sum of all the elements does not fit in a 32-bit integer type. Be sure to use a 64-bit integer type for the prefix sum array.
-</details>
diff --git a/problems/k-similar-strings/README.md b/problems/k-similar-strings/README.md
deleted file mode 100644
index 75314f709..000000000
--- a/problems/k-similar-strings/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../car-fleet "Car Fleet")
-　　　　　　　　　　　　　　　　
-[Next >](../exam-room "Exam Room")
-
-## [854. K-Similar Strings (Hard)](https://leetcode.com/problems/k-similar-strings "相似度为 K 的字符串")
-
-<p>Strings <code>s1</code> and <code>s2</code> are <code>k</code><strong>-similar</strong> (for some non-negative integer <code>k</code>) if we can swap the positions of two letters in <code>s1</code> exactly <code>k</code> times so that the resulting string equals <code>s2</code>.</p>
-
-<p>Given two anagrams <code>s1</code> and <code>s2</code>, return the smallest <code>k</code> for which <code>s1</code> and <code>s2</code> are <code>k</code><strong>-similar</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s1 = "ab", s2 = "ba"
-<strong>Output:</strong> 1
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s1 = "abc", s2 = "bca"
-<strong>Output:</strong> 2
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s1 = "abac", s2 = "baca"
-<strong>Output:</strong> 2
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> s1 = "aabc", s2 = "abca"
-<strong>Output:</strong> 2
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s1.length &lt;= 20</code></li>
-	<li><code>s2.length == s1.length</code></li>
-	<li><code>s1</code> and <code>s2</code> contain only lowercase letters from the set <code>{&#39;a&#39;, &#39;b&#39;, &#39;c&#39;, &#39;d&#39;, &#39;e&#39;, &#39;f&#39;}</code>.</li>
-	<li><code>s2</code> is an anagram of <code>s1</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Couples Holding Hands](../couples-holding-hands) (Hard)
diff --git a/problems/k-similar-strings/k_similar_strings.go b/problems/k-similar-strings/k_similar_strings.go
deleted file mode 100644
index fd55ef300..000000000
--- a/problems/k-similar-strings/k_similar_strings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem854
diff --git a/problems/k-similar-strings/k_similar_strings_test.go b/problems/k-similar-strings/k_similar_strings_test.go
deleted file mode 100644
index fd55ef300..000000000
--- a/problems/k-similar-strings/k_similar_strings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem854
diff --git a/problems/k-th-smallest-in-lexicographical-order/README.md b/problems/k-th-smallest-in-lexicographical-order/README.md
deleted file mode 100644
index b5ef1c26b..000000000
--- a/problems/k-th-smallest-in-lexicographical-order/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ternary-expression-parser "Ternary Expression Parser")
-　　　　　　　　　　　　　　　　
-[Next >](../arranging-coins "Arranging Coins")
-
-## [440. K-th Smallest in Lexicographical Order (Hard)](https://leetcode.com/problems/k-th-smallest-in-lexicographical-order "字典序的第K小数字")
-
-<p>Given two integers <code>n</code> and <code>k</code>, return <em>the</em> <code>k<sup>th</sup></code> <em>lexicographically smallest integer in the range</em> <code>[1, n]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 13, k = 2
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> The lexicographical order is [1, 10, 11, 12, 13, 2, 3, 4, 5, 6, 7, 8, 9], so the second smallest number is 10.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, k = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
diff --git a/problems/k-th-smallest-in-lexicographical-order/k_th_smallest_in_lexicographical_order.go b/problems/k-th-smallest-in-lexicographical-order/k_th_smallest_in_lexicographical_order.go
deleted file mode 100644
index 516359e79..000000000
--- a/problems/k-th-smallest-in-lexicographical-order/k_th_smallest_in_lexicographical_order.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem440
diff --git a/problems/k-th-smallest-in-lexicographical-order/k_th_smallest_in_lexicographical_order_test.go b/problems/k-th-smallest-in-lexicographical-order/k_th_smallest_in_lexicographical_order_test.go
deleted file mode 100644
index 516359e79..000000000
--- a/problems/k-th-smallest-in-lexicographical-order/k_th_smallest_in_lexicographical_order_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem440
diff --git a/problems/k-th-smallest-prime-fraction/README.md b/problems/k-th-smallest-prime-fraction/README.md
deleted file mode 100644
index 4a7f6f0c0..000000000
--- a/problems/k-th-smallest-prime-fraction/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../is-graph-bipartite "Is Graph Bipartite?")
-　　　　　　　　　　　　　　　　
-[Next >](../cheapest-flights-within-k-stops "Cheapest Flights Within K Stops")
-
-## [786. K-th Smallest Prime Fraction (Hard)](https://leetcode.com/problems/k-th-smallest-prime-fraction "第 K 个最小的素数分数")
-
-<p>You are given a sorted integer array <code>arr</code> containing <code>1</code> and <strong>prime</strong> numbers, where all the integers of <code>arr</code> are unique. You are also given an integer <code>k</code>.</p>
-
-<p>For every <code>i</code> and <code>j</code> where <code>0 &lt;= i &lt; j &lt; arr.length</code>, we consider the fraction <code>arr[i] / arr[j]</code>.</p>
-
-<p>Return <em>the</em> <code>k<sup>th</sup></code> <em>smallest fraction considered</em>. Return your answer as an array of integers of size <code>2</code>, where <code>answer[0] == arr[i]</code> and <code>answer[1] == arr[j]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,5], k = 3
-<strong>Output:</strong> [2,5]
-<strong>Explanation:</strong> The fractions to be considered in sorted order are:
-1/5, 1/3, 2/5, 1/2, 3/5, and 2/3.
-The third fraction is 2/5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,7], k = 1
-<strong>Output:</strong> [1,7]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>arr[0] == 1</code></li>
-	<li><code>arr[i]</code> is a <strong>prime</strong> number for <code>i &gt; 0</code>.</li>
-	<li>All the numbers of <code>arr</code> are <strong>unique</strong> and sorted in <strong>strictly increasing</strong> order.</li>
-	<li><code>1 &lt;= k &lt;= arr.length * (arr.length - 1) / 2</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Kth Smallest Element in a Sorted Matrix](../kth-smallest-element-in-a-sorted-matrix) (Medium)
-  1. [Kth Smallest Number in Multiplication Table](../kth-smallest-number-in-multiplication-table) (Hard)
-  1. [Find K-th Smallest Pair Distance](../find-k-th-smallest-pair-distance) (Hard)
diff --git a/problems/k-th-smallest-prime-fraction/k_th_smallest_prime_fraction.go b/problems/k-th-smallest-prime-fraction/k_th_smallest_prime_fraction.go
deleted file mode 100644
index afc23ec8c..000000000
--- a/problems/k-th-smallest-prime-fraction/k_th_smallest_prime_fraction.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem786
diff --git a/problems/k-th-smallest-prime-fraction/k_th_smallest_prime_fraction_test.go b/problems/k-th-smallest-prime-fraction/k_th_smallest_prime_fraction_test.go
deleted file mode 100644
index afc23ec8c..000000000
--- a/problems/k-th-smallest-prime-fraction/k_th_smallest_prime_fraction_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem786
diff --git a/problems/k-th-symbol-in-grammar/README.md b/problems/k-th-symbol-in-grammar/README.md
deleted file mode 100644
index 3830d8866..000000000
--- a/problems/k-th-symbol-in-grammar/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../swim-in-rising-water "Swim in Rising Water")
-　　　　　　　　　　　　　　　　
-[Next >](../reaching-points "Reaching Points")
-
-## [779. K-th Symbol in Grammar (Medium)](https://leetcode.com/problems/k-th-symbol-in-grammar "第K个语法符号")
-
-<p>We build a table of <code>n</code> rows (<strong>1-indexed</strong>). We start by writing <code>0</code> in the <code>1<sup>st</sup></code> row. Now in every subsequent row, we look at the previous row and replace each occurrence of <code>0</code> with <code>01</code>, and each occurrence of <code>1</code> with <code>10</code>.</p>
-
-<ul>
-	<li>For example, for <code>n = 3</code>, the <code>1<sup>st</sup></code> row is <code>0</code>, the <code>2<sup>nd</sup></code> row is <code>01</code>, and the <code>3<sup>rd</sup></code> row is <code>0110</code>.</li>
-</ul>
-
-<p>Given two integer <code>n</code> and <code>k</code>, return the <code>k<sup>th</sup></code> (<strong>1-indexed</strong>) symbol in the <code>n<sup>th</sup></code> row of a table of <code>n</code> rows.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, k = 1
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> row 1: <u>0</u>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, k = 1
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-row 1: 0
-row 2: <u>0</u>1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, k = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-row 1: 0
-row 2: 0<u>1</u>
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 1
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-row 1: 0
-row 2: 01
-row 3: <u>0</u>110
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 30</code></li>
-	<li><code>1 &lt;= k &lt;= 2<sup>n - 1</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to represent the current (N, K) in terms of some (N-1, prevK).  What is prevK ?
-</details>
diff --git a/problems/k-th-symbol-in-grammar/k_th_symbol_in_grammar.go b/problems/k-th-symbol-in-grammar/k_th_symbol_in_grammar.go
deleted file mode 100644
index 5b757475a..000000000
--- a/problems/k-th-symbol-in-grammar/k_th_symbol_in_grammar.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem779
diff --git a/problems/k-th-symbol-in-grammar/k_th_symbol_in_grammar_test.go b/problems/k-th-symbol-in-grammar/k_th_symbol_in_grammar_test.go
deleted file mode 100644
index 5b757475a..000000000
--- a/problems/k-th-symbol-in-grammar/k_th_symbol_in_grammar_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem779
diff --git a/problems/keep-multiplying-found-values-by-two/README.md b/problems/keep-multiplying-found-values-by-two/README.md
deleted file mode 100644
index bb4be6ff6..000000000
--- a/problems/keep-multiplying-found-values-by-two/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-passengers-in-each-bus-ii "The Number of Passengers in Each Bus II")
-　　　　　　　　　　　　　　　　
-[Next >](../all-divisions-with-the-highest-score-of-a-binary-array "All Divisions With the Highest Score of a Binary Array")
-
-## [2154. Keep Multiplying Found Values by Two (Easy)](https://leetcode.com/problems/keep-multiplying-found-values-by-two "将找到的值乘以 2")
-
-<p>You are given an array of integers <code>nums</code>. You are also given an integer <code>original</code> which is the first number that needs to be searched for in <code>nums</code>.</p>
-
-<p>You then do the following steps:</p>
-
-<ol>
-	<li>If <code>original</code> is found in <code>nums</code>, <strong>multiply</strong> it by two (i.e., set <code>original = 2 * original</code>).</li>
-	<li>Otherwise, <strong>stop</strong> the process.</li>
-	<li><strong>Repeat</strong> this process with the new number as long as you keep finding the number.</li>
-</ol>
-
-<p>Return <em>the <strong>final</strong> value of </em><code>original</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,3,6,1,12], original = 3
-<strong>Output:</strong> 24
-<strong>Explanation:</strong> 
-- 3 is found in nums. 3 is multiplied by 2 to obtain 6.
-- 6 is found in nums. 6 is multiplied by 2 to obtain 12.
-- 12 is found in nums. 12 is multiplied by 2 to obtain 24.
-- 24 is not found in nums. Thus, 24 is returned.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,7,9], original = 4
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-- 4 is not found in nums. Thus, 4 is returned.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i], original &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Repeatedly iterate through the array and check if the current value of original is in the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If original is not found, stop and return its current value.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Otherwise, multiply original by 2 and repeat the process.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use set data structure to check the existence faster.
-</details>
diff --git a/problems/keyboard-row/README.md b/problems/keyboard-row/README.md
deleted file mode 100644
index eb993a5b6..000000000
--- a/problems/keyboard-row/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-maze-iii "The Maze III")
-　　　　　　　　　　　　　　　　
-[Next >](../find-mode-in-binary-search-tree "Find Mode in Binary Search Tree")
-
-## [500. Keyboard Row (Easy)](https://leetcode.com/problems/keyboard-row "键盘行")
-
-<p>Given an array of strings <code>words</code>, return <em>the words that can be typed using letters of the alphabet on only one row of American keyboard like the image below</em>.</p>
-
-<p>In the <strong>American keyboard</strong>:</p>
-
-<ul>
-	<li>the first row consists of the characters <code>&quot;qwertyuiop&quot;</code>,</li>
-	<li>the second row consists of the characters <code>&quot;asdfghjkl&quot;</code>, and</li>
-	<li>the third row consists of the characters <code>&quot;zxcvbnm&quot;</code>.</li>
-</ul>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/10/12/keyboard.png" style="width: 800px; max-width: 600px; height: 267px;" />
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;Hello&quot;,&quot;Alaska&quot;,&quot;Dad&quot;,&quot;Peace&quot;]
-<strong>Output:</strong> [&quot;Alaska&quot;,&quot;Dad&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;omk&quot;]
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;adsdf&quot;,&quot;sfd&quot;]
-<strong>Output:</strong> [&quot;adsdf&quot;,&quot;sfd&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 20</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 100</code></li>
-	<li><code>words[i]</code> consists of English letters (both lowercase and uppercase).&nbsp;</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/keyboard-row/keyboard_row.go b/problems/keyboard-row/keyboard_row.go
deleted file mode 100644
index cccd086b4..000000000
--- a/problems/keyboard-row/keyboard_row.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem500
diff --git a/problems/keyboard-row/keyboard_row_test.go b/problems/keyboard-row/keyboard_row_test.go
deleted file mode 100644
index cccd086b4..000000000
--- a/problems/keyboard-row/keyboard_row_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem500
diff --git a/problems/keys-and-rooms/README.md b/problems/keys-and-rooms/README.md
deleted file mode 100644
index 0e91287a1..000000000
--- a/problems/keys-and-rooms/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../magic-squares-in-grid "Magic Squares In Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../split-array-into-fibonacci-sequence "Split Array into Fibonacci Sequence")
-
-## [841. Keys and Rooms (Medium)](https://leetcode.com/problems/keys-and-rooms "钥匙和房间")
-
-<p>There are <code>n</code> rooms labeled from <code>0</code> to <code>n - 1</code>&nbsp;and all the rooms are locked except for room <code>0</code>. Your goal is to visit all the rooms. However, you cannot enter a locked room without having its key.</p>
-
-<p>When you visit a room, you may find a set of <strong>distinct keys</strong> in it. Each key has a number on it, denoting which room it unlocks, and you can take all of them with you to unlock the other rooms.</p>
-
-<p>Given an array <code>rooms</code> where <code>rooms[i]</code> is the set of keys that you can obtain if you visited room <code>i</code>, return <code>true</code> <em>if you can visit <strong>all</strong> the rooms, or</em> <code>false</code> <em>otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rooms = [[1],[2],[3],[]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 
-We visit room 0 and pick up key 1.
-We then visit room 1 and pick up key 2.
-We then visit room 2 and pick up key 3.
-We then visit room 3.
-Since we were able to visit every room, we return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rooms = [[1,3],[3,0,1],[2],[0]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> We can not enter room number 2 since the only key that unlocks it is in that room.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == rooms.length</code></li>
-	<li><code>2 &lt;= n &lt;= 1000</code></li>
-	<li><code>0 &lt;= rooms[i].length &lt;= 1000</code></li>
-	<li><code>1 &lt;= sum(rooms[i].length) &lt;= 3000</code></li>
-	<li><code>0 &lt;= rooms[i][j] &lt; n</code></li>
-	<li>All the values of <code>rooms[i]</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [Graph Valid Tree](../graph-valid-tree) (Medium)
diff --git a/problems/keys-and-rooms/keys_and_rooms.go b/problems/keys-and-rooms/keys_and_rooms.go
deleted file mode 100644
index e97d946ae..000000000
--- a/problems/keys-and-rooms/keys_and_rooms.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem841
diff --git a/problems/keys-and-rooms/keys_and_rooms_test.go b/problems/keys-and-rooms/keys_and_rooms_test.go
deleted file mode 100644
index e97d946ae..000000000
--- a/problems/keys-and-rooms/keys_and_rooms_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem841
diff --git a/problems/kids-with-the-greatest-number-of-candies/README.md b/problems/kids-with-the-greatest-number-of-candies/README.md
deleted file mode 100644
index 248845bf8..000000000
--- a/problems/kids-with-the-greatest-number-of-candies/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree "Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../max-difference-you-can-get-from-changing-an-integer "Max Difference You Can Get From Changing an Integer")
-
-## [1431. Kids With the Greatest Number of Candies (Easy)](https://leetcode.com/problems/kids-with-the-greatest-number-of-candies "拥有最多糖果的孩子")
-
-<p>There are <code>n</code> kids with candies. You are given an integer array <code>candies</code>, where each <code>candies[i]</code> represents the number of candies the <code>i<sup>th</sup></code> kid has, and an integer <code>extraCandies</code>, denoting the number of extra candies that you have.</p>
-
-<p>Return <em>a boolean array </em><code>result</code><em> of length </em><code>n</code><em>, where </em><code>result[i]</code><em> is </em><code>true</code><em> if, after giving the </em><code>i<sup>th</sup></code><em> kid all the </em><code>extraCandies</code><em>, they will have the <strong>greatest</strong> number of candies among all the kids</em><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>Note that <strong>multiple</strong> kids can have the <strong>greatest</strong> number of candies.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> candies = [2,3,5,1,3], extraCandies = 3
-<strong>Output:</strong> [true,true,true,false,true] 
-<strong>Explanation:</strong> If you give all extraCandies to:
-- Kid 1, they will have 2 + 3 = 5 candies, which is the greatest among the kids.
-- Kid 2, they will have 3 + 3 = 6 candies, which is the greatest among the kids.
-- Kid 3, they will have 5 + 3 = 8 candies, which is the greatest among the kids.
-- Kid 4, they will have 1 + 3 = 4 candies, which is not the greatest among the kids.
-- Kid 5, they will have 3 + 3 = 6 candies, which is the greatest among the kids.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> candies = [4,2,1,1,2], extraCandies = 1
-<strong>Output:</strong> [true,false,false,false,false] 
-<strong>Explanation:</strong> There is only 1 extra candy.
-Kid 1 will always have the greatest number of candies, even if a different kid is given the extra candy.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> candies = [12,1,12], extraCandies = 10
-<strong>Output:</strong> [true,false,true]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == candies.length</code></li>
-	<li><code>2 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= candies[i] &lt;= 100</code></li>
-	<li><code>1 &lt;= extraCandies &lt;= 50</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use greedy approach. For each kid check if candies[i] + extraCandies ≥ maximum in Candies[i].
-</details>
diff --git a/problems/kill-process/README.md b/problems/kill-process/README.md
deleted file mode 100644
index bd317f457..000000000
--- a/problems/kill-process/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-unsorted-continuous-subarray "Shortest Unsorted Continuous Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-operation-for-two-strings "Delete Operation for Two Strings")
-
-## [582. Kill Process (Medium)](https://leetcode.com/problems/kill-process "杀掉进程")
-
-<p>Given <b>n</b> processes, each process has a unique <b>PID (process id)</b> and its <b>PPID (parent process id)</b>. 
-
-<p>Each process only has one parent process, but may have one or more children processes. This is just like a tree structure.  Only one process has PPID that is 0, which means this process has no parent process. All the PIDs will be distinct positive integers.</p>
-
-<p>We use two list of integers to represent a list of processes, where the first list contains PID for each process and the second list contains the corresponding PPID. </p>
- 
-<p>Now given the two lists, and a PID representing a process you want to kill, return a list of PIDs of processes that will be killed in the end. You should assume that when a process is killed, all its children processes will be killed. No order is required for the final answer.</p>
-
-<p><b>Example 1:</b><br />
-<pre><b>Input:</b> 
-pid =  [1, 3, 10, 5]
-ppid = [3, 0, 5, 3]
-kill = 5
-<b>Output:</b> [5,10]
-<b>Explanation:</b> 
-           3
-         /   \
-        1     5
-             /
-            10
-Kill 5 will also kill 10.
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>The given kill id is guaranteed to be one of the given PIDs.</li>
-<li>n >= 1.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
diff --git a/problems/kill-process/kill_process.go b/problems/kill-process/kill_process.go
deleted file mode 100644
index 9114ad996..000000000
--- a/problems/kill-process/kill_process.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem582
diff --git a/problems/kill-process/kill_process_test.go b/problems/kill-process/kill_process_test.go
deleted file mode 100644
index 9114ad996..000000000
--- a/problems/kill-process/kill_process_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem582
diff --git a/problems/knight-dialer/README.md b/problems/knight-dialer/README.md
deleted file mode 100644
index 4184e20d6..000000000
--- a/problems/knight-dialer/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-bridge "Shortest Bridge")
-　　　　　　　　　　　　　　　　
-[Next >](../stamping-the-sequence "Stamping The Sequence")
-
-## [935. Knight Dialer (Medium)](https://leetcode.com/problems/knight-dialer "骑士拨号器")
-
-<p>The chess knight has a <strong>unique movement</strong>,&nbsp;it may move two squares vertically and one square horizontally, or two squares horizontally and one square vertically (with both forming the shape of an <strong>L</strong>). The possible movements of chess knight are shown in this diagaram:</p>
-
-<p>A chess knight can move as indicated in the chess diagram below:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/18/chess.jpg" style="width: 402px; height: 402px;" />
-<p>We have a chess knight and a phone pad as shown below, the knight <strong>can only stand on a numeric cell</strong>&nbsp;(i.e. blue cell).</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/18/phone.jpg" style="width: 242px; height: 322px;" />
-<p>Given an integer <code>n</code>, return how many distinct phone numbers of length <code>n</code> we can dial.</p>
-
-<p>You are allowed to place the knight <strong>on any numeric cell</strong> initially and then you should perform <code>n - 1</code> jumps to dial a number of length <code>n</code>. All jumps should be <strong>valid</strong> knight jumps.</p>
-
-<p>As the answer may be very large, <strong>return the answer modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> We need to dial a number of length 1, so placing the knight over any numeric cell of the 10 cells is sufficient.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 20
-<strong>Explanation:</strong> All the valid number we can dial are [04, 06, 16, 18, 27, 29, 34, 38, 40, 43, 49, 60, 61, 67, 72, 76, 81, 83, 92, 94]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 46
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 104
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3131
-<strong>Output:</strong> 136006598
-<strong>Explanation:</strong> Please take care of the mod.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 5000</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/knight-dialer/knight_dialer.go b/problems/knight-dialer/knight_dialer.go
deleted file mode 100644
index 2f84307c0..000000000
--- a/problems/knight-dialer/knight_dialer.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem935
diff --git a/problems/knight-dialer/knight_dialer_test.go b/problems/knight-dialer/knight_dialer_test.go
deleted file mode 100644
index 2f84307c0..000000000
--- a/problems/knight-dialer/knight_dialer_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem935
diff --git a/problems/knight-probability-in-chessboard/README.md b/problems/knight-probability-in-chessboard/README.md
deleted file mode 100644
index 6d64e64fb..000000000
--- a/problems/knight-probability-in-chessboard/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-univalue-path "Longest Univalue Path")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-sum-of-3-non-overlapping-subarrays "Maximum Sum of 3 Non-Overlapping Subarrays")
-
-## [688. Knight Probability in Chessboard (Medium)](https://leetcode.com/problems/knight-probability-in-chessboard "“马”在棋盘上的概率")
-
-<p>On an <code>n x n</code> chessboard, a knight starts at the cell <code>(row, column)</code> and attempts to make exactly <code>k</code> moves. The rows and columns are <strong>0-indexed</strong>, so the top-left cell is <code>(0, 0)</code>, and the bottom-right cell is <code>(n - 1, n - 1)</code>.</p>
-
-<p>A chess knight has eight possible moves it can make, as illustrated below. Each move is two cells in a cardinal direction, then one cell in an orthogonal direction.</p>
-<img src="https://assets.leetcode.com/uploads/2018/10/12/knight.png" style="width: 300px; height: 300px;" />
-<p>Each time the knight is to move, it chooses one of eight possible moves uniformly at random (even if the piece would go off the chessboard) and moves there.</p>
-
-<p>The knight continues moving until it has made exactly <code>k</code> moves or has moved off the chessboard.</p>
-
-<p>Return <em>the probability that the knight remains on the board after it has stopped moving</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 2, row = 0, column = 0
-<strong>Output:</strong> 0.06250
-<strong>Explanation:</strong> There are two moves (to (1,2), (2,1)) that will keep the knight on the board.
-From each of those positions, there are also two moves that will keep the knight on the board.
-The total probability the knight stays on the board is 0.0625.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, k = 0, row = 0, column = 0
-<strong>Output:</strong> 1.00000
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 25</code></li>
-	<li><code>0 &lt;= k &lt;= 100</code></li>
-	<li><code>0 &lt;= row, column &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Out of Boundary Paths](../out-of-boundary-paths) (Medium)
diff --git a/problems/knight-probability-in-chessboard/knight_probability_in_chessboard.go b/problems/knight-probability-in-chessboard/knight_probability_in_chessboard.go
deleted file mode 100644
index a6ded7522..000000000
--- a/problems/knight-probability-in-chessboard/knight_probability_in_chessboard.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem688
diff --git a/problems/knight-probability-in-chessboard/knight_probability_in_chessboard_test.go b/problems/knight-probability-in-chessboard/knight_probability_in_chessboard_test.go
deleted file mode 100644
index a6ded7522..000000000
--- a/problems/knight-probability-in-chessboard/knight_probability_in_chessboard_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem688
diff --git a/problems/koko-eating-bananas/README.md b/problems/koko-eating-bananas/README.md
deleted file mode 100644
index 1a72a6186..000000000
--- a/problems/koko-eating-bananas/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../walking-robot-simulation "Walking Robot Simulation")
-　　　　　　　　　　　　　　　　
-[Next >](../middle-of-the-linked-list "Middle of the Linked List")
-
-## [875. Koko Eating Bananas (Medium)](https://leetcode.com/problems/koko-eating-bananas "爱吃香蕉的珂珂")
-
-<p>Koko loves to eat bananas. There are <code>n</code> piles of bananas, the <code>i<sup>th</sup></code> pile has <code>piles[i]</code> bananas. The guards have gone and will come back in <code>h</code> hours.</p>
-
-<p>Koko can decide her bananas-per-hour eating speed of <code>k</code>. Each hour, she chooses some pile of bananas and eats <code>k</code> bananas from that pile. If the pile has less than <code>k</code> bananas, she eats all of them instead and will not eat any more bananas during this hour.</p>
-
-<p>Koko likes to eat slowly but still wants to finish eating all the bananas before the guards return.</p>
-
-<p>Return <em>the minimum integer</em> <code>k</code> <em>such that she can eat all the bananas within</em> <code>h</code> <em>hours</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [3,6,7,11], h = 8
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [30,11,23,4,20], h = 5
-<strong>Output:</strong> 30
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [30,11,23,4,20], h = 6
-<strong>Output:</strong> 23
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= piles.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>piles.length &lt;= h &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= piles[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Minimize Max Distance to Gas Station](../minimize-max-distance-to-gas-station) (Hard)
-  1. [Minimized Maximum of Products Distributed to Any Store](../minimized-maximum-of-products-distributed-to-any-store) (Medium)
diff --git a/problems/koko-eating-bananas/koko_eating_bananas.go b/problems/koko-eating-bananas/koko_eating_bananas.go
deleted file mode 100644
index f60cb1950..000000000
--- a/problems/koko-eating-bananas/koko_eating_bananas.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem875
diff --git a/problems/koko-eating-bananas/koko_eating_bananas_test.go b/problems/koko-eating-bananas/koko_eating_bananas_test.go
deleted file mode 100644
index f60cb1950..000000000
--- a/problems/koko-eating-bananas/koko_eating_bananas_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem875
diff --git a/problems/kth-ancestor-of-a-tree-node/README.md b/problems/kth-ancestor-of-a-tree-node/README.md
deleted file mode 100644
index b453b8438..000000000
--- a/problems/kth-ancestor-of-a-tree-node/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-days-to-make-m-bouquets "Minimum Number of Days to Make m Bouquets")
-　　　　　　　　　　　　　　　　
-[Next >](../group-sold-products-by-the-date "Group Sold Products By The Date")
-
-## [1483. Kth Ancestor of a Tree Node (Hard)](https://leetcode.com/problems/kth-ancestor-of-a-tree-node "树节点的第 K 个祖先")
-
-<p>You are given a tree with <code>n</code> nodes numbered from <code>0</code> to <code>n - 1</code> in the form of a parent array <code>parent</code> where <code>parent[i]</code> is the parent of <code>i<sup>th</sup></code> node. The root of the tree is node <code>0</code>. Find the <code>k<sup>th</sup></code> ancestor of a given node.</p>
-
-<p>The <code>k<sup>th</sup></code> ancestor of a tree node is the <code>k<sup>th</sup></code> node in the path from that node to the root node.</p>
-
-<p>Implement the <code>TreeAncestor</code> class:</p>
-
-<ul>
-	<li><code>TreeAncestor(int n, int[] parent)</code> Initializes the object with the number of nodes in the tree and the parent array.</li>
-	<li><code>int getKthAncestor(int node, int k)</code> return the <code>k<sup>th</sup></code> ancestor of the given node <code>node</code>. If there is no such ancestor, return <code>-1</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/08/28/1528_ex1.png" style="width: 396px; height: 262px;" />
-<pre>
-<strong>Input</strong>
-[&quot;TreeAncestor&quot;, &quot;getKthAncestor&quot;, &quot;getKthAncestor&quot;, &quot;getKthAncestor&quot;]
-[[7, [-1, 0, 0, 1, 1, 2, 2]], [3, 1], [5, 2], [6, 3]]
-<strong>Output</strong>
-[null, 1, 0, -1]
-
-<strong>Explanation</strong>
-TreeAncestor treeAncestor = new TreeAncestor(7, [-1, 0, 0, 1, 1, 2, 2]);
-treeAncestor.getKthAncestor(3, 1); // returns 1 which is the parent of 3
-treeAncestor.getKthAncestor(5, 2); // returns 0 which is the grandparent of 5
-treeAncestor.getKthAncestor(6, 3); // returns -1 because there is no such ancestor</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>parent.length == n</code></li>
-	<li><code>parent[0] == -1</code></li>
-	<li><code>0 &lt;= parent[i] &lt; n</code> for all <code>0 &lt; i &lt; n</code></li>
-	<li><code>0 &lt;= node &lt; n</code></li>
-	<li>There will be at most <code>5 * 10<sup>4</sup></code> queries.</li>
-</ul>
-
-### Related Topics
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The queries must be answered efficiently to avoid time limit exceeded verdict.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use sparse table (dynamic programming application) to travel the tree upwards in a fast way.
-</details>
diff --git a/problems/kth-distinct-string-in-an-array/README.md b/problems/kth-distinct-string-in-an-array/README.md
deleted file mode 100644
index ecdafd738..000000000
--- a/problems/kth-distinct-string-in-an-array/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-separate-sentence-into-rows "Minimum Cost to Separate Sentence Into Rows")
-　　　　　　　　　　　　　　　　
-[Next >](../two-best-non-overlapping-events "Two Best Non-Overlapping Events")
-
-## [2053. Kth Distinct String in an Array (Easy)](https://leetcode.com/problems/kth-distinct-string-in-an-array "数组中第 K 个独一无二的字符串")
-
-<p>A <strong>distinct string</strong> is a string that is present only <strong>once</strong> in an array.</p>
-
-<p>Given an array of strings <code>arr</code>, and an integer <code>k</code>, return <em>the </em><code>k<sup>th</sup></code><em> <strong>distinct string</strong> present in </em><code>arr</code>. If there are <strong>fewer</strong> than <code>k</code> distinct strings, return <em>an <strong>empty string </strong></em><code>&quot;&quot;</code>.</p>
-
-<p>Note that the strings are considered in the <strong>order in which they appear</strong> in the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [&quot;d&quot;,&quot;b&quot;,&quot;c&quot;,&quot;b&quot;,&quot;c&quot;,&quot;a&quot;], k = 2
-<strong>Output:</strong> &quot;a&quot;
-<strong>Explanation:</strong>
-The only distinct strings in arr are &quot;d&quot; and &quot;a&quot;.
-&quot;d&quot; appears 1<sup>st</sup>, so it is the 1<sup>st</sup> distinct string.
-&quot;a&quot; appears 2<sup>nd</sup>, so it is the 2<sup>nd</sup> distinct string.
-Since k == 2, &quot;a&quot; is returned. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [&quot;aaa&quot;,&quot;aa&quot;,&quot;a&quot;], k = 1
-<strong>Output:</strong> &quot;aaa&quot;
-<strong>Explanation:</strong>
-All strings in arr are distinct, so the 1<sup>st</sup> string &quot;aaa&quot; is returned.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [&quot;a&quot;,&quot;b&quot;,&quot;a&quot;], k = 3
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong>
-The only distinct string is &quot;b&quot;. Since there are fewer than 3 distinct strings, we return an empty string &quot;&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= arr[i].length &lt;= 5</code></li>
-	<li><code>arr[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try 'mapping' the strings to check if they are unique or not.
-</details>
diff --git a/problems/kth-largest-element-in-a-stream/README.md b/problems/kth-largest-element-in-a-stream/README.md
deleted file mode 100644
index 5c9061b41..000000000
--- a/problems/kth-largest-element-in-a-stream/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../search-in-a-sorted-array-of-unknown-size "Search in a Sorted Array of Unknown Size")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-search "Binary Search")
-
-## [703. Kth Largest Element in a Stream (Easy)](https://leetcode.com/problems/kth-largest-element-in-a-stream "数据流中的第 K 大元素")
-
-<p>Design a class to find the <code>k<sup>th</sup></code> largest element in a stream. Note that it is the <code>k<sup>th</sup></code> largest element in the sorted order, not the <code>k<sup>th</sup></code> distinct element.</p>
-
-<p>Implement <code>KthLargest</code> class:</p>
-
-<ul>
-	<li><code>KthLargest(int k, int[] nums)</code> Initializes the object with the integer <code>k</code> and the stream of integers <code>nums</code>.</li>
-	<li><code>int add(int val)</code> Appends the integer <code>val</code> to the stream and returns the element representing the <code>k<sup>th</sup></code> largest element in the stream.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;KthLargest&quot;, &quot;add&quot;, &quot;add&quot;, &quot;add&quot;, &quot;add&quot;, &quot;add&quot;]
-[[3, [4, 5, 8, 2]], [3], [5], [10], [9], [4]]
-<strong>Output</strong>
-[null, 4, 5, 5, 8, 8]
-
-<strong>Explanation</strong>
-KthLargest kthLargest = new KthLargest(3, [4, 5, 8, 2]);
-kthLargest.add(3);   // return 4
-kthLargest.add(5);   // return 5
-kthLargest.add(10);  // return 5
-kthLargest.add(9);   // return 8
-kthLargest.add(4);   // return 8
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= val &lt;= 10<sup>4</sup></code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>add</code>.</li>
-	<li>It is guaranteed that there will be at least <code>k</code> elements in the array when you search for the <code>k<sup>th</sup></code> element.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Kth Largest Element in an Array](../kth-largest-element-in-an-array) (Medium)
diff --git a/problems/kth-largest-element-in-a-stream/kth_largest_element_in_a_stream.go b/problems/kth-largest-element-in-a-stream/kth_largest_element_in_a_stream.go
deleted file mode 100644
index 1064eb8b0..000000000
--- a/problems/kth-largest-element-in-a-stream/kth_largest_element_in_a_stream.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem703
diff --git a/problems/kth-largest-element-in-a-stream/kth_largest_element_in_a_stream_test.go b/problems/kth-largest-element-in-a-stream/kth_largest_element_in_a_stream_test.go
deleted file mode 100644
index 1064eb8b0..000000000
--- a/problems/kth-largest-element-in-a-stream/kth_largest_element_in_a_stream_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem703
diff --git a/problems/kth-largest-element-in-an-array/README.md b/problems/kth-largest-element-in-an-array/README.md
deleted file mode 100644
index d96cba83e..000000000
--- a/problems/kth-largest-element-in-an-array/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-palindrome "Shortest Palindrome")
-　　　　　　　　　　　　　　　　
-[Next >](../combination-sum-iii "Combination Sum III")
-
-## [215. Kth Largest Element in an Array (Medium)](https://leetcode.com/problems/kth-largest-element-in-an-array "数组中的第K个最大元素")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the</em> <code>k<sup>th</sup></code> <em>largest element in the array</em>.</p>
-
-<p>Note that it is the <code>k<sup>th</sup></code> largest element in the sorted order, not the <code>k<sup>th</sup></code> distinct element.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [3,2,1,5,6,4], k = 2
-<strong>Output:</strong> 5
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [3,2,3,1,2,4,5,5,6], k = 4
-<strong>Output:</strong> 4
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Quickselect](../../tag/quickselect/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Wiggle Sort II](../wiggle-sort-ii) (Medium)
-  1. [Top K Frequent Elements](../top-k-frequent-elements) (Medium)
-  1. [Third Maximum Number](../third-maximum-number) (Easy)
-  1. [Kth Largest Element in a Stream](../kth-largest-element-in-a-stream) (Easy)
-  1. [K Closest Points to Origin](../k-closest-points-to-origin) (Medium)
diff --git a/problems/kth-largest-element-in-an-array/kth_largest_element_in_an_array.go b/problems/kth-largest-element-in-an-array/kth_largest_element_in_an_array.go
deleted file mode 100644
index 3d77d00b9..000000000
--- a/problems/kth-largest-element-in-an-array/kth_largest_element_in_an_array.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package problem215
-
-import "sort"
-
-func findKthLargest(nums []int, k int) int {
-	sort.Ints(nums)
-	return nums[len(nums)-k]
-}
diff --git a/problems/kth-largest-element-in-an-array/kth_largest_element_in_an_array_test.go b/problems/kth-largest-element-in-an-array/kth_largest_element_in_an_array_test.go
deleted file mode 100644
index 0f9840280..000000000
--- a/problems/kth-largest-element-in-an-array/kth_largest_element_in_an_array_test.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem215
-
-import "testing"
-
-type testType struct {
-	in   []int
-	k    int
-	want int
-}
-
-func TestFindKthLargest(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 2, 1, 5, 6, 4},
-			k:    2,
-			want: 5,
-		}, {
-			in:   []int{3, 2, 3, 1, 2, 4, 5, 5, 6},
-			k:    4,
-			want: 4,
-		},
-	}
-	for _, tt := range tests {
-		got := findKthLargest(tt.in, tt.k)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/kth-missing-positive-number/README.md b/problems/kth-missing-positive-number/README.md
deleted file mode 100644
index 243391cfb..000000000
--- a/problems/kth-missing-positive-number/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../guess-the-majority-in-a-hidden-array "Guess the Majority in a Hidden Array")
-　　　　　　　　　　　　　　　　
-[Next >](../can-convert-string-in-k-moves "Can Convert String in K Moves")
-
-## [1539. Kth Missing Positive Number (Easy)](https://leetcode.com/problems/kth-missing-positive-number "第 k 个缺失的正整数")
-
-<p>Given an array <code>arr</code>&nbsp;of positive integers&nbsp;sorted in a <strong>strictly increasing order</strong>, and an integer <code><font face="monospace">k</font></code>.</p>
-
-<p><em>Find the </em><font face="monospace"><code>k<sup>th</sup></code></font><em>&nbsp;positive integer that is missing from this array.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,3,4,7,11], k = 5
-<strong>Output:</strong> 9
-<strong>Explanation: </strong>The missing positive integers are [1,5,6,8,9,10,12,13,...]. The 5<sup>th</sup>&nbsp;missing positive integer is 9.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4], k = 2
-<strong>Output:</strong> 6
-<strong>Explanation: </strong>The missing positive integers are [5,6,7,...]. The 2<sup>nd</sup> missing positive integer is 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 1000</code></li>
-	<li><code>1 &lt;= k &lt;= 1000</code></li>
-	<li><code>arr[i] &lt; arr[j]</code> for <code>1 &lt;= i &lt; j &lt;= arr.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep track of how many positive numbers are missing as you scan the array.
-</details>
diff --git a/problems/kth-smallest-element-in-a-bst/README.md b/problems/kth-smallest-element-in-a-bst/README.md
deleted file mode 100644
index baf52bc92..000000000
--- a/problems/kth-smallest-element-in-a-bst/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../majority-element-ii "Majority Element II")
-　　　　　　　　　　　　　　　　
-[Next >](../power-of-two "Power of Two")
-
-## [230. Kth Smallest Element in a BST (Medium)](https://leetcode.com/problems/kth-smallest-element-in-a-bst "二叉搜索树中第K小的元素")
-
-<p>Given the <code>root</code> of a binary search tree, and an integer <code>k</code>, return <em>the</em> <code>k<sup>th</sup></code> <em>smallest value (<strong>1-indexed</strong>) of all the values of the nodes in the tree</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/28/kthtree1.jpg" style="width: 212px; height: 301px;" />
-<pre>
-<strong>Input:</strong> root = [3,1,4,null,2], k = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/28/kthtree2.jpg" style="width: 382px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [5,3,6,2,4,null,null,1], k = 3
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is <code>n</code>.</li>
-	<li><code>1 &lt;= k &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> If the BST is modified often (i.e., we can do insert and delete operations) and you need to find the kth smallest frequently, how would you optimize?</p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Inorder Traversal](../binary-tree-inorder-traversal) (Easy)
-  1. [Second Minimum Node In a Binary Tree](../second-minimum-node-in-a-binary-tree) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to utilize the property of a BST.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try in-order traversal. (Credits to @chan13)
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What if you could modify the BST node's structure?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The optimal runtime complexity is O(height of BST).
-</details>
diff --git a/problems/kth-smallest-element-in-a-bst/kth_smallest_element_in_a_bst.go b/problems/kth-smallest-element-in-a-bst/kth_smallest_element_in_a_bst.go
deleted file mode 100644
index f9034309f..000000000
--- a/problems/kth-smallest-element-in-a-bst/kth_smallest_element_in_a_bst.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem230
diff --git a/problems/kth-smallest-element-in-a-bst/kth_smallest_element_in_a_bst_test.go b/problems/kth-smallest-element-in-a-bst/kth_smallest_element_in_a_bst_test.go
deleted file mode 100644
index f9034309f..000000000
--- a/problems/kth-smallest-element-in-a-bst/kth_smallest_element_in_a_bst_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem230
diff --git a/problems/kth-smallest-element-in-a-sorted-matrix/README.md b/problems/kth-smallest-element-in-a-sorted-matrix/README.md
deleted file mode 100644
index acc313d66..000000000
--- a/problems/kth-smallest-element-in-a-sorted-matrix/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../combination-sum-iv "Combination Sum IV")
-　　　　　　　　　　　　　　　　
-[Next >](../design-phone-directory "Design Phone Directory")
-
-## [378. Kth Smallest Element in a Sorted Matrix (Medium)](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix "有序矩阵中第 K 小的元素")
-
-<p>Given an <code>n x n</code> <code>matrix</code> where each of the rows and columns are sorted in ascending order, return <em>the</em> <code>k<sup>th</sup></code> <em>smallest element in the matrix</em>.</p>
-
-<p>Note that it is the <code>k<sup>th</sup></code> smallest element <strong>in the sorted order</strong>, not the <code>k<sup>th</sup></code> <strong>distinct</strong> element.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[1,5,9],[10,11,13],[12,13,15]], k = 8
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> The elements in the matrix are [1,5,9,10,11,12,13,<u><strong>13</strong></u>,15], and the 8<sup>th</sup> smallest number is 13
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[-5]], k = 1
-<strong>Output:</strong> -5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 300</code></li>
-	<li><code>-10<sup>9</sup> &lt;= matrix[i][j] &lt;= 10<sup>9</sup></code></li>
-	<li>All the rows and columns of <code>matrix</code> are <strong>guaranteed</strong> to be sorted in <strong>non-decreasing order</strong>.</li>
-	<li><code>1 &lt;= k &lt;= n<sup>2</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Find K Pairs with Smallest Sums](../find-k-pairs-with-smallest-sums) (Medium)
-  1. [Kth Smallest Number in Multiplication Table](../kth-smallest-number-in-multiplication-table) (Hard)
-  1. [Find K-th Smallest Pair Distance](../find-k-th-smallest-pair-distance) (Hard)
-  1. [K-th Smallest Prime Fraction](../k-th-smallest-prime-fraction) (Hard)
diff --git a/problems/kth-smallest-element-in-a-sorted-matrix/kth_smallest_element_in_a_sorted_matrix.go b/problems/kth-smallest-element-in-a-sorted-matrix/kth_smallest_element_in_a_sorted_matrix.go
deleted file mode 100644
index cc986d4a2..000000000
--- a/problems/kth-smallest-element-in-a-sorted-matrix/kth_smallest_element_in_a_sorted_matrix.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem378
diff --git a/problems/kth-smallest-element-in-a-sorted-matrix/kth_smallest_element_in_a_sorted_matrix_test.go b/problems/kth-smallest-element-in-a-sorted-matrix/kth_smallest_element_in_a_sorted_matrix_test.go
deleted file mode 100644
index cc986d4a2..000000000
--- a/problems/kth-smallest-element-in-a-sorted-matrix/kth_smallest_element_in_a_sorted_matrix_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem378
diff --git a/problems/kth-smallest-instructions/README.md b/problems/kth-smallest-instructions/README.md
deleted file mode 100644
index 5820b7981..000000000
--- a/problems/kth-smallest-instructions/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../furthest-building-you-can-reach "Furthest Building You Can Reach")
-　　　　　　　　　　　　　　　　
-[Next >](../lowest-common-ancestor-of-a-binary-tree-ii "Lowest Common Ancestor of a Binary Tree II")
-
-## [1643. Kth Smallest Instructions (Hard)](https://leetcode.com/problems/kth-smallest-instructions "第 K 条最小指令")
-
-<p>Bob is standing at cell <code>(0, 0)</code>, and he wants to reach <code>destination</code>: <code>(row, column)</code>. He can only travel <strong>right</strong> and <strong>down</strong>. You are going to help Bob by providing <strong>instructions</strong> for him to reach <code>destination</code>.</p>
-
-<p>The <strong>instructions</strong> are represented as a string, where each character is either:</p>
-
-<ul>
-	<li><code>&#39;H&#39;</code>, meaning move horizontally (go <strong>right</strong>), or</li>
-	<li><code>&#39;V&#39;</code>, meaning move vertically (go <strong>down</strong>).</li>
-</ul>
-
-<p>Multiple <strong>instructions</strong> will lead Bob to <code>destination</code>. For example, if <code>destination</code> is <code>(2, 3)</code>, both <code>&quot;HHHVV&quot;</code> and <code>&quot;HVHVH&quot;</code> are valid <strong>instructions</strong>.</p>
-
-<p>However, Bob is very picky. Bob has a lucky number <code>k</code>, and he wants the <code>k<sup>th</sup></code> <strong>lexicographically smallest instructions</strong> that will lead him to <code>destination</code>. <code>k</code> is <strong>1-indexed</strong>.</p>
-
-<p>Given an integer array <code>destination</code> and an integer <code>k</code>, return <em>the </em><code>k<sup>th</sup></code><em> <strong>lexicographically smallest instructions</strong> that will take Bob to </em><code>destination</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/10/12/ex1.png" style="width: 300px; height: 229px;" /></p>
-
-<pre>
-<strong>Input:</strong> destination = [2,3], k = 1
-<strong>Output:</strong> &quot;HHHVV&quot;
-<strong>Explanation:</strong> All the instructions that reach (2, 3) in lexicographic order are as follows:
-[&quot;HHHVV&quot;, &quot;HHVHV&quot;, &quot;HHVVH&quot;, &quot;HVHHV&quot;, &quot;HVHVH&quot;, &quot;HVVHH&quot;, &quot;VHHHV&quot;, &quot;VHHVH&quot;, &quot;VHVHH&quot;, &quot;VVHHH&quot;].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/10/12/ex2.png" style="width: 300px; height: 229px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> destination = [2,3], k = 2
-<strong>Output:</strong> &quot;HHVHV&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/10/12/ex3.png" style="width: 300px; height: 229px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> destination = [2,3], k = 3
-<strong>Output:</strong> &quot;HHVVH&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>destination.length == 2</code></li>
-	<li><code>1 &lt;= row, column &lt;= 15</code></li>
-	<li><code>1 &lt;= k &lt;= nCr(row + column, row)</code>, where <code>nCr(a, b)</code> denotes <code>a</code> choose <code>b</code>​​​​​.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There are nCr(row + column, row) possible instructions to reach (row, column).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try building the instructions one step at a time. How many instructions start with "H", and how does this compare with k?
-</details>
diff --git a/problems/kth-smallest-number-in-multiplication-table/README.md b/problems/kth-smallest-number-in-multiplication-table/README.md
deleted file mode 100644
index 92bfa7196..000000000
--- a/problems/kth-smallest-number-in-multiplication-table/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../beautiful-arrangement-ii "Beautiful Arrangement II")
-　　　　　　　　　　　　　　　　
-[Next >](../trim-a-binary-search-tree "Trim a Binary Search Tree")
-
-## [668. Kth Smallest Number in Multiplication Table (Hard)](https://leetcode.com/problems/kth-smallest-number-in-multiplication-table "乘法表中第k小的数")
-
-<p>Nearly everyone has used the <a href="https://en.wikipedia.org/wiki/Multiplication_table" target="_blank">Multiplication Table</a>. The multiplication table of size <code>m x n</code> is an integer matrix <code>mat</code> where <code>mat[i][j] == i * j</code> (<strong>1-indexed</strong>).</p>
-
-<p>Given three integers <code>m</code>, <code>n</code>, and <code>k</code>, return <em>the </em><code>k<sup>th</sup></code><em> smallest element in the </em><code>m x n</code><em> multiplication table</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/02/multtable1-grid.jpg" style="width: 500px; height: 254px;" />
-<pre>
-<strong>Input:</strong> m = 3, n = 3, k = 5
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The 5<sup>th</sup> smallest number is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/02/multtable2-grid.jpg" style="width: 493px; height: 293px;" />
-<pre>
-<strong>Input:</strong> m = 2, n = 3, k = 6
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The 6<sup>th</sup> smallest number is 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m, n &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= k &lt;= m * n</code></li>
-</ul>
-
-### Related Topics
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Kth Smallest Element in a Sorted Matrix](../kth-smallest-element-in-a-sorted-matrix) (Medium)
-  1. [Find K-th Smallest Pair Distance](../find-k-th-smallest-pair-distance) (Hard)
-  1. [K-th Smallest Prime Fraction](../k-th-smallest-prime-fraction) (Hard)
diff --git a/problems/kth-smallest-number-in-multiplication-table/kth_smallest_number_in_multiplication_table.go b/problems/kth-smallest-number-in-multiplication-table/kth_smallest_number_in_multiplication_table.go
deleted file mode 100644
index 4e79be994..000000000
--- a/problems/kth-smallest-number-in-multiplication-table/kth_smallest_number_in_multiplication_table.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem668
diff --git a/problems/kth-smallest-number-in-multiplication-table/kth_smallest_number_in_multiplication_table_test.go b/problems/kth-smallest-number-in-multiplication-table/kth_smallest_number_in_multiplication_table_test.go
deleted file mode 100644
index 4e79be994..000000000
--- a/problems/kth-smallest-number-in-multiplication-table/kth_smallest_number_in_multiplication_table_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem668
diff --git a/problems/kth-smallest-product-of-two-sorted-arrays/README.md b/problems/kth-smallest-product-of-two-sorted-arrays/README.md
deleted file mode 100644
index a603687f3..000000000
--- a/problems/kth-smallest-product-of-two-sorted-arrays/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-time-when-the-network-becomes-idle "The Time When the Network Becomes Idle")
-　　　　　　　　　　　　　　　　
-[Next >](../accepted-candidates-from-the-interviews "Accepted Candidates From the Interviews")
-
-## [2040. Kth Smallest Product of Two Sorted Arrays (Hard)](https://leetcode.com/problems/kth-smallest-product-of-two-sorted-arrays "两个有序数组的第 K 小乘积")
-
-Given two <strong>sorted 0-indexed</strong> integer arrays <code>nums1</code> and <code>nums2</code> as well as an integer <code>k</code>, return <em>the </em><code>k<sup>th</sup></code><em> (<strong>1-based</strong>) smallest product of </em><code>nums1[i] * nums2[j]</code><em> where </em><code>0 &lt;= i &lt; nums1.length</code><em> and </em><code>0 &lt;= j &lt; nums2.length</code>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [2,5], nums2 = [3,4], k = 2
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> The 2 smallest products are:
-- nums1[0] * nums2[0] = 2 * 3 = 6
-- nums1[0] * nums2[1] = 2 * 4 = 8
-The 2<sup>nd</sup> smallest product is 8.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [-4,-2,0,3], nums2 = [2,4], k = 6
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The 6 smallest products are:
-- nums1[0] * nums2[1] = (-4) * 4 = -16
-- nums1[0] * nums2[0] = (-4) * 2 = -8
-- nums1[1] * nums2[1] = (-2) * 4 = -8
-- nums1[1] * nums2[0] = (-2) * 2 = -4
-- nums1[2] * nums2[0] = 0 * 2 = 0
-- nums1[2] * nums2[1] = 0 * 4 = 0
-The 6<sup>th</sup> smallest product is 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [-2,-1,0,1,2], nums2 = [-3,-1,2,4,5], k = 3
-<strong>Output:</strong> -6
-<strong>Explanation:</strong> The 3 smallest products are:
-- nums1[0] * nums2[4] = (-2) * 5 = -10
-- nums1[0] * nums2[3] = (-2) * 4 = -8
-- nums1[4] * nums2[0] = 2 * (-3) = -6
-The 3<sup>rd</sup> smallest product is -6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums1[i], nums2[j] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= k &lt;= nums1.length * nums2.length</code></li>
-	<li><code>nums1</code> and <code>nums2</code> are sorted.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we split this problem into four cases depending on the sign of the numbers?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we binary search the value?
-</details>
diff --git a/problems/kth-smallest-subarray-sum/README.md b/problems/kth-smallest-subarray-sum/README.md
deleted file mode 100644
index e58ecad9f..000000000
--- a/problems/kth-smallest-subarray-sum/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../leetcodify-friends-recommendations "Leetcodify Friends Recommendations")
-　　　　　　　　　　　　　　　　
-[Next >](../leetcodify-similar-friends "Leetcodify Similar Friends")
-
-## [1918. Kth Smallest Subarray Sum (Medium)](https://leetcode.com/problems/kth-smallest-subarray-sum "第 K 小的子数组和·")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can you compute the number of subarrays with a sum less than a given value?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use binary search to help find the answer?
-</details>
diff --git a/problems/largest-1-bordered-square/README.md b/problems/largest-1-bordered-square/README.md
deleted file mode 100644
index b2e11e036..000000000
--- a/problems/largest-1-bordered-square/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../alphabet-board-path "Alphabet Board Path")
-　　　　　　　　　　　　　　　　
-[Next >](../stone-game-ii "Stone Game II")
-
-## [1139. Largest 1-Bordered Square (Medium)](https://leetcode.com/problems/largest-1-bordered-square "最大的以 1 为边界的正方形")
-
-<p>Given a 2D <code>grid</code> of <code>0</code>s and <code>1</code>s, return the number of elements in&nbsp;the largest <strong>square</strong>&nbsp;subgrid that has all <code>1</code>s on its <strong>border</strong>, or <code>0</code> if such a subgrid&nbsp;doesn&#39;t exist in the <code>grid</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,1],[1,0,1],[1,1,1]]
-<strong>Output:</strong> 9
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,0,0]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= grid.length &lt;= 100</code></li>
-	<li><code>1 &lt;= grid[0].length &lt;= 100</code></li>
-	<li><code>grid[i][j]</code> is <code>0</code> or <code>1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each square, know how many ones are up, left, down, and right of this square. You can find it in O(N^2) using dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Now for each square ( O(N^3) ), we can evaluate whether that square is 1-bordered in O(1).
-</details>
diff --git a/problems/largest-bst-subtree/README.md b/problems/largest-bst-subtree/README.md
deleted file mode 100644
index 69c9b4513..000000000
--- a/problems/largest-bst-subtree/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reconstruct-itinerary "Reconstruct Itinerary")
-　　　　　　　　　　　　　　　　
-[Next >](../increasing-triplet-subsequence "Increasing Triplet Subsequence")
-
-## [333. Largest BST Subtree (Medium)](https://leetcode.com/problems/largest-bst-subtree "最大 BST 子树")
-
-<p>Given a binary tree, find the largest subtree which is a Binary Search Tree (BST), where largest means subtree with largest number of nodes in it.</p>
-
-<p><b>Note:</b><br />
-A subtree must include all of its descendants.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input: </strong>[10,5,15,1,8,null,7]
-
-   10 
-   / \ 
-<font color="red">  5</font>  15 
-<font color="red"> / \</font>   \ 
-<font color="red">1   8</font>   7
-
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>The Largest BST Subtree in this case is the highlighted one.
-             The return value is the subtree&#39;s size, which is 3.
-</pre>
-
-<p><b>Follow up:</b><br />
-Can you figure out ways to solve it with O(n) time complexity?</p>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can recursively use algorithm similar to <a href="https://leetcode.com/problems/validate-binary-search-tree/">98. Validate Binary Search Tree</a> at each node of the tree, which will result in O(nlogn) time complexity.
-</details>
diff --git a/problems/largest-bst-subtree/largest_bst_subtree.go b/problems/largest-bst-subtree/largest_bst_subtree.go
deleted file mode 100644
index 4cba35b94..000000000
--- a/problems/largest-bst-subtree/largest_bst_subtree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem333
diff --git a/problems/largest-bst-subtree/largest_bst_subtree_test.go b/problems/largest-bst-subtree/largest_bst_subtree_test.go
deleted file mode 100644
index 4cba35b94..000000000
--- a/problems/largest-bst-subtree/largest_bst_subtree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem333
diff --git a/problems/largest-color-value-in-a-directed-graph/README.md b/problems/largest-color-value-in-a-directed-graph/README.md
deleted file mode 100644
index 9ca2b2ad1..000000000
--- a/problems/largest-color-value-in-a-directed-graph/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-subarray-min-product "Maximum Subarray Min-Product")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-word-with-all-prefixes "Longest Word With All Prefixes")
-
-## [1857. Largest Color Value in a Directed Graph (Hard)](https://leetcode.com/problems/largest-color-value-in-a-directed-graph "有向图中最大颜色值")
-
-<p>There is a <strong>directed graph</strong> of <code>n</code> colored nodes and <code>m</code> edges. The nodes are numbered from <code>0</code> to <code>n - 1</code>.</p>
-
-<p>You are given a string <code>colors</code> where <code>colors[i]</code> is a lowercase English letter representing the <strong>color</strong> of the <code>i<sup>th</sup></code> node in this graph (<strong>0-indexed</strong>). You are also given a 2D array <code>edges</code> where <code>edges[j] = [a<sub>j</sub>, b<sub>j</sub>]</code> indicates that there is a <strong>directed edge</strong> from node <code>a<sub>j</sub></code> to node <code>b<sub>j</sub></code>.</p>
-
-<p>A valid <strong>path</strong> in the graph is a sequence of nodes <code>x<sub>1</sub> -&gt; x<sub>2</sub> -&gt; x<sub>3</sub> -&gt; ... -&gt; x<sub>k</sub></code> such that there is a directed edge from <code>x<sub>i</sub></code> to <code>x<sub>i+1</sub></code> for every <code>1 &lt;= i &lt; k</code>. The <strong>color value</strong> of the path is the number of nodes that are colored the <strong>most frequently</strong> occurring color along that path.</p>
-
-<p>Return <em>the <strong>largest color value</strong> of any valid path in the given graph, or </em><code>-1</code><em> if the graph contains a cycle</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/21/leet1.png" style="width: 400px; height: 182px;" /></p>
-
-<pre>
-<strong>Input:</strong> colors = &quot;abaca&quot;, edges = [[0,1],[0,2],[2,3],[3,4]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The path 0 -&gt; 2 -&gt; 3 -&gt; 4 contains 3 nodes that are colored <code>&quot;a&quot; (red in the above image)</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/21/leet2.png" style="width: 85px; height: 85px;" /></p>
-
-<pre>
-<strong>Input:</strong> colors = &quot;a&quot;, edges = [[0,0]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There is a cycle from 0 to 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == colors.length</code></li>
-	<li><code>m == edges.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= m &lt;= 10<sup>5</sup></code></li>
-	<li><code>colors</code> consists of lowercase English letters.</li>
-	<li><code>0 &lt;= a<sub>j</sub>, b<sub>j</sub>&nbsp;&lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use topological sort.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-let dp[u][c] := the maximum count of vertices with color c of any path starting from vertex u. (by JerryJin2905)
-</details>
diff --git a/problems/largest-component-size-by-common-factor/README.md b/problems/largest-component-size-by-common-factor/README.md
deleted file mode 100644
index a9303e864..000000000
--- a/problems/largest-component-size-by-common-factor/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flip-equivalent-binary-trees "Flip Equivalent Binary Trees")
-　　　　　　　　　　　　　　　　
-[Next >](../verifying-an-alien-dictionary "Verifying an Alien Dictionary")
-
-## [952. Largest Component Size by Common Factor (Hard)](https://leetcode.com/problems/largest-component-size-by-common-factor "按公因数计算最大组件大小")
-
-<p>You are given an integer array of unique positive integers <code>nums</code>. Consider the following graph:</p>
-
-<ul>
-	<li>There are <code>nums.length</code> nodes, labeled <code>nums[0]</code> to <code>nums[nums.length - 1]</code>,</li>
-	<li>There is an undirected edge between <code>nums[i]</code> and <code>nums[j]</code> if <code>nums[i]</code> and <code>nums[j]</code> share a common factor greater than <code>1</code>.</li>
-</ul>
-
-<p>Return <em>the size of the largest connected component in the graph</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/01/ex1.png" style="width: 500px; height: 97px;" />
-<pre>
-<strong>Input:</strong> nums = [4,6,15,35]
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/01/ex2.png" style="width: 500px; height: 85px;" />
-<pre>
-<strong>Input:</strong> nums = [20,50,9,63]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/01/ex3.png" style="width: 500px; height: 260px;" />
-<pre>
-<strong>Input:</strong> nums = [2,3,6,7,4,12,21,39]
-<strong>Output:</strong> 8
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-	<li>All the values of <code>nums</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
diff --git a/problems/largest-component-size-by-common-factor/largest_component_size_by_common_factor.go b/problems/largest-component-size-by-common-factor/largest_component_size_by_common_factor.go
deleted file mode 100644
index ee981ed8d..000000000
--- a/problems/largest-component-size-by-common-factor/largest_component_size_by_common_factor.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem952
diff --git a/problems/largest-component-size-by-common-factor/largest_component_size_by_common_factor_test.go b/problems/largest-component-size-by-common-factor/largest_component_size_by_common_factor_test.go
deleted file mode 100644
index ee981ed8d..000000000
--- a/problems/largest-component-size-by-common-factor/largest_component_size_by_common_factor_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem952
diff --git a/problems/largest-divisible-subset/README.md b/problems/largest-divisible-subset/README.md
deleted file mode 100644
index 18b71216d..000000000
--- a/problems/largest-divisible-subset/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-perfect-square "Valid Perfect Square")
-　　　　　　　　　　　　　　　　
-[Next >](../plus-one-linked-list "Plus One Linked List")
-
-## [368. Largest Divisible Subset (Medium)](https://leetcode.com/problems/largest-divisible-subset "最大整除子集")
-
-<p>Given a set of <strong>distinct</strong> positive integers <code>nums</code>, return the largest subset <code>answer</code> such that every pair <code>(answer[i], answer[j])</code> of elements in this subset satisfies:</p>
-
-<ul>
-	<li><code>answer[i] % answer[j] == 0</code>, or</li>
-	<li><code>answer[j] % answer[i] == 0</code></li>
-</ul>
-
-<p>If there are multiple solutions, return any of them.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> [1,2]
-<strong>Explanation:</strong> [1,3] is also accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,4,8]
-<strong>Output:</strong> [1,2,4,8]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 2 * 10<sup>9</sup></code></li>
-	<li>All the integers in <code>nums</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/largest-divisible-subset/largest_divisible_subset.go b/problems/largest-divisible-subset/largest_divisible_subset.go
deleted file mode 100644
index ec2517d3b..000000000
--- a/problems/largest-divisible-subset/largest_divisible_subset.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem368
diff --git a/problems/largest-divisible-subset/largest_divisible_subset_test.go b/problems/largest-divisible-subset/largest_divisible_subset_test.go
deleted file mode 100644
index ec2517d3b..000000000
--- a/problems/largest-divisible-subset/largest_divisible_subset_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem368
diff --git a/problems/largest-magic-square/README.md b/problems/largest-magic-square/README.md
deleted file mode 100644
index c13ed708f..000000000
--- a/problems/largest-magic-square/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-student-that-will-replace-the-chalk "Find the Student that Will Replace the Chalk")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-change-the-final-value-of-expression "Minimum Cost to Change the Final Value of Expression")
-
-## [1895. Largest Magic Square (Medium)](https://leetcode.com/problems/largest-magic-square "最大的幻方")
-
-<p>A <code>k x k</code> <strong>magic square</strong> is a <code>k x k</code> grid filled with integers such that every row sum, every column sum, and both diagonal sums are <strong>all equal</strong>. The integers in the magic square <strong>do not have to be distinct</strong>. Every <code>1 x 1</code> grid is trivially a <strong>magic square</strong>.</p>
-
-<p>Given an <code>m x n</code> integer <code>grid</code>, return <em>the <strong>size</strong> (i.e., the side length </em><code>k</code><em>) of the <strong>largest magic square</strong> that can be found within this grid</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/29/magicsquare-grid.jpg" style="width: 413px; height: 335px;" />
-<pre>
-<strong>Input:</strong> grid = [[7,1,4,5,6],[2,5,1,6,4],[1,5,4,3,2],[1,2,7,3,4]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The largest magic square has a size of 3.
-Every row sum, column sum, and diagonal sum of this magic square is equal to 12.
-- Row sums: 5+1+6 = 5+4+3 = 2+7+3 = 12
-- Column sums: 5+5+2 = 1+4+7 = 6+3+3 = 12
-- Diagonal sums: 5+4+3 = 6+4+2 = 12
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/29/magicsquare2-grid.jpg" style="width: 333px; height: 255px;" />
-<pre>
-<strong>Input:</strong> grid = [[5,1,3,1],[9,3,3,1],[1,3,3,8]]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>1 &lt;= grid[i][j] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check all squares in the matrix and find the largest one.
-</details>
diff --git a/problems/largest-merge-of-two-strings/README.md b/problems/largest-merge-of-two-strings/README.md
deleted file mode 100644
index 35fd263b1..000000000
--- a/problems/largest-merge-of-two-strings/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-score-from-removing-stones "Maximum Score From Removing Stones")
-　　　　　　　　　　　　　　　　
-[Next >](../closest-subsequence-sum "Closest Subsequence Sum")
-
-## [1754. Largest Merge Of Two Strings (Medium)](https://leetcode.com/problems/largest-merge-of-two-strings "构造字典序最大的合并字符串")
-
-<p>You are given two strings <code>word1</code> and <code>word2</code>. You want to construct a string <code>merge</code> in the following way: while either <code>word1</code> or <code>word2</code> are non-empty, choose <strong>one</strong> of the following options:</p>
-
-<ul>
-	<li>If <code>word1</code> is non-empty, append the <strong>first</strong> character in <code>word1</code> to <code>merge</code> and delete it from <code>word1</code>.
-	<ul>
-		<li>For example, if <code>word1 = &quot;abc&quot; </code>and <code>merge = &quot;dv&quot;</code>, then after choosing this operation, <code>word1 = &quot;bc&quot;</code> and <code>merge = &quot;dva&quot;</code>.</li>
-	</ul>
-	</li>
-	<li>If <code>word2</code> is non-empty, append the <strong>first</strong> character in <code>word2</code> to <code>merge</code> and delete it from <code>word2</code>.
-	<ul>
-		<li>For example, if <code>word2 = &quot;abc&quot; </code>and <code>merge = &quot;&quot;</code>, then after choosing this operation, <code>word2 = &quot;bc&quot;</code> and <code>merge = &quot;a&quot;</code>.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <em>the lexicographically <strong>largest</strong> </em><code>merge</code><em> you can construct</em>.</p>
-
-<p>A string <code>a</code> is lexicographically larger than a string <code>b</code> (of the same length) if in the first position where <code>a</code> and <code>b</code> differ, <code>a</code> has a character strictly larger than the corresponding character in <code>b</code>. For example, <code>&quot;abcd&quot;</code> is lexicographically larger than <code>&quot;abcc&quot;</code> because the first position they differ is at the fourth character, and <code>d</code> is greater than <code>c</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;cabaa&quot;, word2 = &quot;bcaaa&quot;
-<strong>Output:</strong> &quot;cbcabaaaaa&quot;
-<strong>Explanation:</strong> One way to get the lexicographically largest merge is:
-- Take from word1: merge = &quot;c&quot;, word1 = &quot;abaa&quot;, word2 = &quot;bcaaa&quot;
-- Take from word2: merge = &quot;cb&quot;, word1 = &quot;abaa&quot;, word2 = &quot;caaa&quot;
-- Take from word2: merge = &quot;cbc&quot;, word1 = &quot;abaa&quot;, word2 = &quot;aaa&quot;
-- Take from word1: merge = &quot;cbca&quot;, word1 = &quot;baa&quot;, word2 = &quot;aaa&quot;
-- Take from word1: merge = &quot;cbcab&quot;, word1 = &quot;aa&quot;, word2 = &quot;aaa&quot;
-- Append the remaining 5 a&#39;s from word1 and word2 at the end of merge.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;abcabc&quot;, word2 = &quot;abdcaba&quot;
-<strong>Output:</strong> &quot;abdcabcabcaba&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word1.length, word2.length &lt;= 3000</code></li>
-	<li><code>word1</code> and <code>word2</code> consist only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build the result character by character. At each step, you choose a character from one of the two strings.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the next character of the first string is larger than that of the second string, or vice versa, it's optimal to use the larger one.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If both are equal, think of a criteria that lets you decide which string to consume the next character from.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-You should choose the next character from the larger string.
-</details>
diff --git a/problems/largest-multiple-of-three/README.md b/problems/largest-multiple-of-three/README.md
deleted file mode 100644
index 91ce76469..000000000
--- a/problems/largest-multiple-of-three/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../closest-divisors "Closest Divisors")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-trusted-contacts-of-a-customer "Number of Trusted Contacts of a Customer")
-
-## [1363. Largest Multiple of Three (Hard)](https://leetcode.com/problems/largest-multiple-of-three "形成三的最大倍数")
-
-<p>Given an array of digits <code>digits</code>, return <em>the largest multiple of <strong>three</strong> that can be formed by concatenating some of the given digits in <strong>any order</strong></em>. If there is no answer return an empty string.</p>
-
-<p>Since the answer may not fit in an integer data type, return the answer as a string. Note that the returning answer must not contain unnecessary leading zeros.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [8,1,9]
-<strong>Output:</strong> &quot;981&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [8,6,7,1,0]
-<strong>Output:</strong> &quot;8760&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [1]
-<strong>Output:</strong> &quot;&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= digits.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= digits[i] &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A number is a multiple of three if and only if its sum of digits is a multiple of three.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-To find the maximum number, try to maximize the number of digits of the number.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Sort the digits in descending order to find the maximum number.
-</details>
diff --git a/problems/largest-number-after-mutating-substring/README.md b/problems/largest-number-after-mutating-substring/README.md
deleted file mode 100644
index 4dd0ddd4a..000000000
--- a/problems/largest-number-after-mutating-substring/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-digits-of-string-after-convert "Sum of Digits of String After Convert")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-compatibility-score-sum "Maximum Compatibility Score Sum")
-
-## [1946. Largest Number After Mutating Substring (Medium)](https://leetcode.com/problems/largest-number-after-mutating-substring "子字符串突变后可能得到的最大整数")
-
-<p>You are given a string <code>num</code>, which represents a large integer. You are also given a <strong>0-indexed</strong> integer array <code>change</code> of length <code>10</code> that maps each digit <code>0-9</code> to another digit. More formally, digit <code>d</code> maps to digit <code>change[d]</code>.</p>
-
-<p>You may <strong>choose</strong> to <b>mutate a single substring</b> of <code>num</code>. To mutate a substring, replace each digit <code>num[i]</code> with the digit it maps to in <code>change</code> (i.e. replace <code>num[i]</code> with <code>change[num[i]]</code>).</p>
-
-<p>Return <em>a string representing the <strong>largest</strong> possible integer after <strong>mutating</strong> (or choosing not to) a <strong>single substring</strong> of </em><code>num</code>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within the string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;<u>1</u>32&quot;, change = [9,8,5,0,3,6,4,2,6,8]
-<strong>Output:</strong> &quot;<u>8</u>32&quot;
-<strong>Explanation:</strong> Replace the substring &quot;1&quot;:
-- 1 maps to change[1] = 8.
-Thus, &quot;<u>1</u>32&quot; becomes &quot;<u>8</u>32&quot;.
-&quot;832&quot; is the largest number that can be created, so return it.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;<u>021</u>&quot;, change = [9,4,3,5,7,2,1,9,0,6]
-<strong>Output:</strong> &quot;<u>934</u>&quot;
-<strong>Explanation:</strong> Replace the substring &quot;021&quot;:
-- 0 maps to change[0] = 9.
-- 2 maps to change[2] = 3.
-- 1 maps to change[1] = 4.
-Thus, &quot;<u>021</u>&quot; becomes &quot;<u>934</u>&quot;.
-&quot;934&quot; is the largest number that can be created, so return it.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;5&quot;, change = [1,4,7,5,3,2,5,6,9,4]
-<strong>Output:</strong> &quot;5&quot;
-<strong>Explanation:</strong> &quot;5&quot; is already the largest number that can be created, so return it.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>num</code> consists of only digits <code>0-9</code>.</li>
-	<li><code>change.length == 10</code></li>
-	<li><code>0 &lt;= change[d] &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Should you change a digit if the new digit is smaller than the original?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If changing the first digit and the last digit both make the number bigger, but you can only change one of them; which one should you change?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Changing numbers closer to the front is always better
-</details>
diff --git a/problems/largest-number-at-least-twice-of-others/README.md b/problems/largest-number-at-least-twice-of-others/README.md
deleted file mode 100644
index 3c2ffe674..000000000
--- a/problems/largest-number-at-least-twice-of-others/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../min-cost-climbing-stairs "Min Cost Climbing Stairs")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-completing-word "Shortest Completing Word")
-
-## [747. Largest Number At Least Twice of Others (Easy)](https://leetcode.com/problems/largest-number-at-least-twice-of-others "至少是其他数字两倍的最大数")
-
-<p>You are given an integer array <code>nums</code> where the largest integer is <strong>unique</strong>.</p>
-
-<p>Determine whether the largest element in the array is <strong>at least twice</strong> as much as every other number in the array. If it is, return <em>the <strong>index</strong> of the largest element, or return </em><code>-1</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,6,1,0]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 6 is the largest integer.
-For every other number in the array x, 6 is at least twice as big as x.
-The index of value 6 is 1, so we return 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> 4 is less than twice the value of 3, so we return -1.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> 1 is trivially at least twice the value as any other number because there are no other numbers.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 50</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 100</code></li>
-	<li>The largest element in <code>nums</code> is unique.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Scan through the array to find the unique largest element `m`, keeping track of it's index `maxIndex`.
-
-Scan through the array again.  If we find some `x != m` with `m < 2*x`, we should return `-1`.
-
-Otherwise, we should return `maxIndex`.
-</details>
diff --git a/problems/largest-number-at-least-twice-of-others/largest_number_at_least_twice_of_others.go b/problems/largest-number-at-least-twice-of-others/largest_number_at_least_twice_of_others.go
deleted file mode 100644
index 32ad1431e..000000000
--- a/problems/largest-number-at-least-twice-of-others/largest_number_at_least_twice_of_others.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem747
-
-func dominantIndex(nums []int) int {
-	ans, sec := 0, 0
-	for i, v := range nums {
-		if v > nums[ans] {
-			ans, sec = i, nums[ans]
-		} else if v > sec && i != ans {
-			sec = v
-		}
-	}
-	if nums[ans] >= 2*sec {
-		return ans
-	}
-	return -1
-}
diff --git a/problems/largest-number-at-least-twice-of-others/largest_number_at_least_twice_of_others_test.go b/problems/largest-number-at-least-twice-of-others/largest_number_at_least_twice_of_others_test.go
deleted file mode 100644
index babf59dd5..000000000
--- a/problems/largest-number-at-least-twice-of-others/largest_number_at_least_twice_of_others_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem747
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestDominantIndex(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 6, 1, 0},
-			want: 1,
-		},
-		{
-			in:   []int{1, 2, 3, 4},
-			want: -1,
-		},
-		{
-			in:   []int{1},
-			want: 0,
-		},
-		{
-			in:   []int{0, 0, 3, 2},
-			want: -1,
-		},
-		{
-			in:   []int{3, 0, 0, 2},
-			want: -1,
-		},
-	}
-	for _, tt := range tests {
-		got := dominantIndex(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/largest-number/README.md b/problems/largest-number/README.md
deleted file mode 100644
index 308b5ad2c..000000000
--- a/problems/largest-number/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rank-scores "Rank Scores")
-　　　　　　　　　　　　　　　　
-[Next >](../consecutive-numbers "Consecutive Numbers")
-
-## [179. Largest Number (Medium)](https://leetcode.com/problems/largest-number "最大数")
-
-<p>Given a list of non-negative integers <code>nums</code>, arrange them such that they form the largest number and return it.</p>
-
-<p>Since the result may be very large, so you need to return a string instead of an integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,2]
-<strong>Output:</strong> &quot;210&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,30,34,5,9]
-<strong>Output:</strong> &quot;9534330&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/largest-number/largest_number.go b/problems/largest-number/largest_number.go
deleted file mode 100644
index d27db607f..000000000
--- a/problems/largest-number/largest_number.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem179
diff --git a/problems/largest-number/largest_number_test.go b/problems/largest-number/largest_number_test.go
deleted file mode 100644
index d27db607f..000000000
--- a/problems/largest-number/largest_number_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem179
diff --git a/problems/largest-odd-number-in-string/README.md b/problems/largest-odd-number-in-string/README.md
deleted file mode 100644
index 433ce9589..000000000
--- a/problems/largest-odd-number-in-string/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../depth-of-bst-given-insertion-order "Depth of BST Given Insertion Order")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-full-rounds-you-have-played "The Number of Full Rounds You Have Played")
-
-## [1903. Largest Odd Number in String (Easy)](https://leetcode.com/problems/largest-odd-number-in-string "字符串中的最大奇数")
-
-<p>You are given a string <code>num</code>, representing a large integer. Return <em>the <strong>largest-valued odd</strong> integer (as a string) that is a <strong>non-empty substring</strong> of </em><code>num</code><em>, or an empty string </em><code>&quot;&quot;</code><em> if no odd integer exists</em>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;52&quot;
-<strong>Output:</strong> &quot;5&quot;
-<strong>Explanation:</strong> The only non-empty substrings are &quot;5&quot;, &quot;2&quot;, and &quot;52&quot;. &quot;5&quot; is the only odd number.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;4206&quot;
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> There are no odd numbers in &quot;4206&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;35427&quot;
-<strong>Output:</strong> &quot;35427&quot;
-<strong>Explanation:</strong> &quot;35427&quot; is already an odd number.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>num</code> only consists of digits and does not contain any leading zeros.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-In what order should you iterate through the digits?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If an odd number exists, where must the number start from?
-</details>
diff --git a/problems/largest-palindrome-product/README.md b/problems/largest-palindrome-product/README.md
deleted file mode 100644
index 0dd3baf0d..000000000
--- a/problems/largest-palindrome-product/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../generate-random-point-in-a-circle "Generate Random Point in a Circle")
-　　　　　　　　　　　　　　　　
-[Next >](../sliding-window-median "Sliding Window Median")
-
-## [479. Largest Palindrome Product (Hard)](https://leetcode.com/problems/largest-palindrome-product "最大回文数乘积")
-
-<p>Given an integer n, return <em>the <strong>largest palindromic integer</strong> that can be represented as the product of two <code>n</code>-digits integers</em>. Since the answer can be very large, return it <strong>modulo</strong> <code>1337</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 987
-Explanation: 99 x 91 = 9009, 9009 % 1337 = 987
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 9
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 8</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/largest-palindrome-product/largest_palindrome_product.go b/problems/largest-palindrome-product/largest_palindrome_product.go
deleted file mode 100644
index 1fbae16df..000000000
--- a/problems/largest-palindrome-product/largest_palindrome_product.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem479
diff --git a/problems/largest-palindrome-product/largest_palindrome_product_test.go b/problems/largest-palindrome-product/largest_palindrome_product_test.go
deleted file mode 100644
index 1fbae16df..000000000
--- a/problems/largest-palindrome-product/largest_palindrome_product_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem479
diff --git a/problems/largest-perimeter-triangle/README.md b/problems/largest-perimeter-triangle/README.md
deleted file mode 100644
index 0bc3e6422..000000000
--- a/problems/largest-perimeter-triangle/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../odd-even-jump "Odd Even Jump")
-　　　　　　　　　　　　　　　　
-[Next >](../squares-of-a-sorted-array "Squares of a Sorted Array")
-
-## [976. Largest Perimeter Triangle (Easy)](https://leetcode.com/problems/largest-perimeter-triangle "三角形的最大周长")
-
-<p>Given an integer array <code>nums</code>, return <em>the largest perimeter of a triangle with a non-zero area, formed from three of these lengths</em>. If it is impossible to form any triangle of a non-zero area, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,2]
-<strong>Output:</strong> 5
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Largest Triangle Area](../largest-triangle-area) (Easy)
diff --git a/problems/largest-perimeter-triangle/largest_perimeter_triangle.go b/problems/largest-perimeter-triangle/largest_perimeter_triangle.go
deleted file mode 100644
index 23422421a..000000000
--- a/problems/largest-perimeter-triangle/largest_perimeter_triangle.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem976
-
-import "sort"
-
-func largestPerimeter(A []int) int {
-	sort.Ints(A)
-	for i := len(A) - 3; i >= 0; i-- {
-		if A[i]+A[i+1] > A[i+2] {
-			return A[i] + A[i+1] + A[i+2]
-		}
-	}
-	return 0
-}
diff --git a/problems/largest-perimeter-triangle/largest_perimeter_triangle_test.go b/problems/largest-perimeter-triangle/largest_perimeter_triangle_test.go
deleted file mode 100644
index 9719d3c1b..000000000
--- a/problems/largest-perimeter-triangle/largest_perimeter_triangle_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem976
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestLargestPerimeter(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{2, 1, 2},
-			want: 5,
-		},
-		{
-			in:   []int{1, 2, 1},
-			want: 0,
-		},
-		{
-			in:   []int{3, 2, 3, 4},
-			want: 10,
-		},
-		{
-			in:   []int{3, 6, 2, 3},
-			want: 8,
-		},
-	}
-	for _, tt := range tests {
-		got := largestPerimeter(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/largest-plus-sign/README.md b/problems/largest-plus-sign/README.md
deleted file mode 100644
index 16767ccb8..000000000
--- a/problems/largest-plus-sign/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partition-labels "Partition Labels")
-　　　　　　　　　　　　　　　　
-[Next >](../couples-holding-hands "Couples Holding Hands")
-
-## [764. Largest Plus Sign (Medium)](https://leetcode.com/problems/largest-plus-sign "最大加号标志")
-
-<p>You are given an integer <code>n</code>. You have an <code>n x n</code> binary grid <code>grid</code> with all values initially <code>1</code>&#39;s except for some indices given in the array <code>mines</code>. The <code>i<sup>th</sup></code> element of the array <code>mines</code> is defined as <code>mines[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> where <code>grid[x<sub>i</sub>][y<sub>i</sub>] == 0</code>.</p>
-
-<p>Return <em>the order of the largest <strong>axis-aligned</strong> plus sign of </em>1<em>&#39;s contained in </em><code>grid</code>. If there is none, return <code>0</code>.</p>
-
-<p>An <strong>axis-aligned plus sign</strong> of <code>1</code>&#39;s of order <code>k</code> has some center <code>grid[r][c] == 1</code> along with four arms of length <code>k - 1</code> going up, down, left, and right, and made of <code>1</code>&#39;s. Note that there could be <code>0</code>&#39;s or <code>1</code>&#39;s beyond the arms of the plus sign, only the relevant area of the plus sign is checked for <code>1</code>&#39;s.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/13/plus1-grid.jpg" style="width: 404px; height: 405px;" />
-<pre>
-<strong>Input:</strong> n = 5, mines = [[4,2]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> In the above grid, the largest plus sign can only be of order 2. One of them is shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/13/plus2-grid.jpg" style="width: 84px; height: 85px;" />
-<pre>
-<strong>Input:</strong> n = 1, mines = [[0,0]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no plus sign, so return 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-	<li><code>1 &lt;= mines.length &lt;= 5000</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt; n</code></li>
-	<li>All the pairs <code>(x<sub>i</sub>, y<sub>i</sub>)</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Maximal Square](../maximal-square) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each direction such as "left", find left[r][c] = the number of 1s you will see before a zero starting at r, c and walking left.  You can find this in N^2 time with a dp.  The largest plus sign at r, c is just the minimum of left[r][c], up[r][c] etc.
-</details>
diff --git a/problems/largest-plus-sign/largest_plus_sign.go b/problems/largest-plus-sign/largest_plus_sign.go
deleted file mode 100644
index 715bcb4c4..000000000
--- a/problems/largest-plus-sign/largest_plus_sign.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem764
diff --git a/problems/largest-plus-sign/largest_plus_sign_test.go b/problems/largest-plus-sign/largest_plus_sign_test.go
deleted file mode 100644
index 715bcb4c4..000000000
--- a/problems/largest-plus-sign/largest_plus_sign_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem764
diff --git a/problems/largest-rectangle-in-histogram/README.md b/problems/largest-rectangle-in-histogram/README.md
deleted file mode 100644
index 9257981d2..000000000
--- a/problems/largest-rectangle-in-histogram/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-duplicates-from-sorted-list "Remove Duplicates from Sorted List")
-　　　　　　　　　　　　　　　　
-[Next >](../maximal-rectangle "Maximal Rectangle")
-
-## [84. Largest Rectangle in Histogram (Hard)](https://leetcode.com/problems/largest-rectangle-in-histogram "柱状图中最大的矩形")
-
-<p>Given an array of integers <code>heights</code> representing the histogram&#39;s bar height where the width of each bar is <code>1</code>, return <em>the area of the largest rectangle in the histogram</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/histogram.jpg" style="width: 522px; height: 242px;" />
-<pre>
-<strong>Input:</strong> heights = [2,1,5,6,2,3]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> The above is a histogram where width of each bar is 1.
-The largest rectangle is shown in the red area, which has an area = 10 units.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/histogram-1.jpg" style="width: 202px; height: 362px;" />
-<pre>
-<strong>Input:</strong> heights = [2,4]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= heights.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= heights[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Maximal Rectangle](../maximal-rectangle) (Hard)
diff --git a/problems/largest-rectangle-in-histogram/largest_rectangle_in_histogram.go b/problems/largest-rectangle-in-histogram/largest_rectangle_in_histogram.go
deleted file mode 100644
index 2b367347a..000000000
--- a/problems/largest-rectangle-in-histogram/largest_rectangle_in_histogram.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem84
diff --git a/problems/largest-rectangle-in-histogram/largest_rectangle_in_histogram_test.go b/problems/largest-rectangle-in-histogram/largest_rectangle_in_histogram_test.go
deleted file mode 100644
index 2b367347a..000000000
--- a/problems/largest-rectangle-in-histogram/largest_rectangle_in_histogram_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem84
diff --git a/problems/largest-subarray-length-k/README.md b/problems/largest-subarray-length-k/README.md
deleted file mode 100644
index 29371e2c9..000000000
--- a/problems/largest-subarray-length-k/README.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-xor-with-an-element-from-array "Maximum XOR With an Element From Array")
-　　　　　　　　　　　　　　　　
-[Next >](../biggest-window-between-visits "Biggest Window Between Visits")
-
-## [1708. Largest Subarray Length K (Easy)](https://leetcode.com/problems/largest-subarray-length-k "长度为 K 的最大子数组")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Search for the largest integer in the range [0, n - k]
-</details>
-
-<details>
-<summary>Hint 2</summary>
-This integer is the first element in the subarray. You should take it with the k - 1 elements after it.
-</details>
diff --git a/problems/largest-submatrix-with-rearrangements/README.md b/problems/largest-submatrix-with-rearrangements/README.md
deleted file mode 100644
index fd5ac277b..000000000
--- a/problems/largest-submatrix-with-rearrangements/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tuple-with-same-product "Tuple with Same Product")
-　　　　　　　　　　　　　　　　
-[Next >](../cat-and-mouse-ii "Cat and Mouse II")
-
-## [1727. Largest Submatrix With Rearrangements (Medium)](https://leetcode.com/problems/largest-submatrix-with-rearrangements "重新排列后的最大子矩阵")
-
-<p>You are given a binary matrix <code>matrix</code> of size <code>m x n</code>, and you are allowed to rearrange the <strong>columns</strong> of the <code>matrix</code> in any order.</p>
-
-<p>Return <em>the area of the largest submatrix within </em><code>matrix</code><em> where <strong>every</strong> element of the submatrix is </em><code>1</code><em> after reordering the columns optimally.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/29/screenshot-2020-12-30-at-40536-pm.png" style="width: 500px; height: 240px;" />
-<pre>
-<strong>Input:</strong> matrix = [[0,0,1],[1,1,1],[1,0,1]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> You can rearrange the columns as shown above.
-The largest submatrix of 1s, in bold, has an area of 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/29/screenshot-2020-12-30-at-40852-pm.png" style="width: 500px; height: 62px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,0,1,0,1]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You can rearrange the columns as shown above.
-The largest submatrix of 1s, in bold, has an area of 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[1,1,0],[1,0,1]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Notice that you must rearrange entire columns, and there is no way to make a submatrix of 1s larger than an area of 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m * n &lt;= 10<sup>5</sup></code></li>
-	<li><code>matrix[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each column, find the number of consecutive ones ending at each position.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each row, sort the cumulative ones in non-increasing order and "fit" the largest submatrix.
-</details>
diff --git a/problems/largest-substring-between-two-equal-characters/README.md b/problems/largest-substring-between-two-equal-characters/README.md
deleted file mode 100644
index 46a160a10..000000000
--- a/problems/largest-substring-between-two-equal-characters/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-valid-triplets-that-can-represent-a-country "All Valid Triplets That Can Represent a Country")
-　　　　　　　　　　　　　　　　
-[Next >](../lexicographically-smallest-string-after-applying-operations "Lexicographically Smallest String After Applying Operations")
-
-## [1624. Largest Substring Between Two Equal Characters (Easy)](https://leetcode.com/problems/largest-substring-between-two-equal-characters "两个相同字符之间的最长子字符串")
-
-<p>Given a string <code>s</code>, return <em>the length of the longest substring between two equal characters, excluding the two characters.</em> If there is no such substring return <code>-1</code>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aa&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The optimal substring here is an empty substring between the two <code>&#39;a&#39;s</code>.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abca&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The optimal substring here is &quot;bc&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cbzxy&quot;
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There are no characters that appear twice in s.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 300</code></li>
-	<li><code>s</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try saving the first and last position of each character
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try finding every pair of indexes with equal characters
-</details>
diff --git a/problems/largest-sum-of-averages/README.md b/problems/largest-sum-of-averages/README.md
deleted file mode 100644
index a53338cfd..000000000
--- a/problems/largest-sum-of-averages/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-triangle-area "Largest Triangle Area")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-pruning "Binary Tree Pruning")
-
-## [813. Largest Sum of Averages (Medium)](https://leetcode.com/problems/largest-sum-of-averages "最大平均值和的分组")
-
-<p>You are given an integer array <code>nums</code> and an integer <code>k</code>. You can partition the array into <strong>at most</strong> <code>k</code> non-empty adjacent subarrays. The <strong>score</strong> of a partition is the sum of the averages of each subarray.</p>
-
-<p>Note that the partition must use every integer in <code>nums</code>, and that the score is not necessarily an integer.</p>
-
-<p>Return <em>the maximum <strong>score</strong> you can achieve of all the possible partitions</em>. Answers within <code>10<sup>-6</sup></code> of the actual answer will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,1,2,3,9], k = 3
-<strong>Output:</strong> 20.00000
-<strong>Explanation:</strong> 
-The best choice is to partition nums into [9], [1, 2, 3], [9]. The answer is 9 + (1 + 2 + 3) / 3 + 9 = 20.
-We could have also partitioned nums into [9, 1], [2], [3, 9], for example.
-That partition would lead to a score of 5 + 2 + 6 = 13, which is worse.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5,6,7], k = 4
-<strong>Output:</strong> 20.50000
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= k &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/largest-sum-of-averages/largest_sum_of_averages.go b/problems/largest-sum-of-averages/largest_sum_of_averages.go
deleted file mode 100644
index a4cf7d686..000000000
--- a/problems/largest-sum-of-averages/largest_sum_of_averages.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem813
diff --git a/problems/largest-sum-of-averages/largest_sum_of_averages_test.go b/problems/largest-sum-of-averages/largest_sum_of_averages_test.go
deleted file mode 100644
index a4cf7d686..000000000
--- a/problems/largest-sum-of-averages/largest_sum_of_averages_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem813
diff --git a/problems/largest-time-for-given-digits/README.md b/problems/largest-time-for-given-digits/README.md
deleted file mode 100644
index 73adf0242..000000000
--- a/problems/largest-time-for-given-digits/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bag-of-tokens "Bag of Tokens")
-　　　　　　　　　　　　　　　　
-[Next >](../reveal-cards-in-increasing-order "Reveal Cards In Increasing Order")
-
-## [949. Largest Time for Given Digits (Medium)](https://leetcode.com/problems/largest-time-for-given-digits "给定数字能组成的最大时间")
-
-<p>Given an array&nbsp;<code>arr</code> of 4 digits, find the latest 24-hour time that can be made using each digit <strong>exactly once</strong>.</p>
-
-<p>24-hour times are formatted as <code>&quot;HH:MM&quot;</code>, where <code>HH</code>&nbsp;is between&nbsp;<code>00</code>&nbsp;and&nbsp;<code>23</code>, and&nbsp;<code>MM</code>&nbsp;is between&nbsp;<code>00</code>&nbsp;and&nbsp;<code>59</code>. The earliest 24-hour time is <code>00:00</code>, and the latest is <code>23:59</code>.</p>
-
-<p>Return <em>the latest 24-hour time&nbsp;in&nbsp;<code>&quot;HH:MM&quot;</code> format</em>.&nbsp; If no valid time can be made, return an empty string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4]
-<strong>Output:</strong> &quot;23:41&quot;
-<strong>Explanation:</strong>&nbsp;The valid 24-hour times are &quot;12:34&quot;, &quot;12:43&quot;, &quot;13:24&quot;, &quot;13:42&quot;, &quot;14:23&quot;, &quot;14:32&quot;, &quot;21:34&quot;, &quot;21:43&quot;, &quot;23:14&quot;, and &quot;23:41&quot;. Of these times, &quot;23:41&quot; is the latest.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [5,5,5,5]
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong>&nbsp;There are no valid 24-hour times as &quot;55:55&quot; is not valid.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [0,0,0,0]
-<strong>Output:</strong> &quot;00:00&quot;
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [0,0,1,0]
-<strong>Output:</strong> &quot;10:00&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>arr.length == 4</code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
diff --git a/problems/largest-time-for-given-digits/largest_time_for_given_digits.go b/problems/largest-time-for-given-digits/largest_time_for_given_digits.go
deleted file mode 100644
index 636867d28..000000000
--- a/problems/largest-time-for-given-digits/largest_time_for_given_digits.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem949
-
-import (
-	"fmt"
-	"sort"
-)
-
-func largestTimeFromDigits(A []int) string {
-	sort.Ints(A)
-	for i := 3; i >= 0; i-- {
-		if A[i] < 3 {
-			for j := 3; j >= 0; j-- {
-				if j != i && A[i]*10+A[j] < 24 {
-					for k := 3; k >= 0; k-- {
-						if k != i && k != j && A[k] < 6 {
-							l := 6 - i - j - k
-							return fmt.Sprintf("%d%d:%d%d", A[i], A[j], A[k], A[l])
-						}
-					}
-				}
-			}
-		}
-	}
-	return ""
-}
diff --git a/problems/largest-time-for-given-digits/largest_time_for_given_digits_test.go b/problems/largest-time-for-given-digits/largest_time_for_given_digits_test.go
deleted file mode 100644
index 012db5c04..000000000
--- a/problems/largest-time-for-given-digits/largest_time_for_given_digits_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem949
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want string
-}
-
-func TestLargestTimeFromDigits(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3, 4},
-			want: "23:41",
-		},
-		{
-			in:   []int{5, 5, 5, 5},
-			want: "",
-		},
-		{
-			in:   []int{2, 0, 6, 6},
-			want: "06:26",
-		},
-	}
-	for _, tt := range tests {
-		got := largestTimeFromDigits(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/largest-triangle-area/README.md b/problems/largest-triangle-area/README.md
deleted file mode 100644
index 6e29bdca6..000000000
--- a/problems/largest-triangle-area/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subdomain-visit-count "Subdomain Visit Count")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-sum-of-averages "Largest Sum of Averages")
-
-## [812. Largest Triangle Area (Easy)](https://leetcode.com/problems/largest-triangle-area "最大三角形面积")
-
-<p>Given an array of points on the <strong>X-Y</strong> plane <code>points</code> where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>, return <em>the area of the largest triangle that can be formed by any three different points</em>. Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/04/04/1027.png" style="height: 369px; width: 450px;" />
-<pre>
-<strong>Input:</strong> points = [[0,0],[0,1],[1,0],[0,2],[2,0]]
-<strong>Output:</strong> 2.00000
-<strong>Explanation:</strong> The five points are shown in the above figure. The red triangle is the largest.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[1,0],[0,0],[0,1]]
-<strong>Output:</strong> 0.50000
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= points.length &lt;= 50</code></li>
-	<li><code>-50 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 50</code></li>
-	<li>All the given points are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Largest Perimeter Triangle](../largest-perimeter-triangle) (Easy)
diff --git a/problems/largest-triangle-area/largest_triangle_area.go b/problems/largest-triangle-area/largest_triangle_area.go
deleted file mode 100644
index 5cc2ed3ca..000000000
--- a/problems/largest-triangle-area/largest_triangle_area.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem812
diff --git a/problems/largest-triangle-area/largest_triangle_area_test.go b/problems/largest-triangle-area/largest_triangle_area_test.go
deleted file mode 100644
index 5cc2ed3ca..000000000
--- a/problems/largest-triangle-area/largest_triangle_area_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem812
diff --git a/problems/largest-unique-number/README.md b/problems/largest-unique-number/README.md
deleted file mode 100644
index ee87cb4c9..000000000
--- a/problems/largest-unique-number/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reported-posts-ii "Reported Posts II")
-　　　　　　　　　　　　　　　　
-[Next >](../armstrong-number "Armstrong Number")
-
-## [1133. Largest Unique Number (Easy)](https://leetcode.com/problems/largest-unique-number "最大唯一数")
-
-<p>Given an array of integers <code>A</code>, return the largest integer that only occurs once.</p>
-
-<p>If no integer occurs once, return -1.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[5,7,3,9,4,9,8,3,1]</span>
-<strong>Output: </strong><span id="example-output-1">8</span>
-<strong>Explanation: </strong>
-The maximum integer in the array is 9 but it is repeated. The number 8 occurs only once, so it&#39;s the answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[9,9,8,8]</span>
-<strong>Output: </strong><span id="example-output-1">-1</span>
-<strong>Explanation: </strong>
-There is no number that occurs only once.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= A.length &lt;= 2000</code></li>
-	<li><code>0 &lt;= A[i] &lt;= 1000</code></li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the number of occurrences of each value.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use an array or a hash table to do that.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Look for the largest value with number of occurrences = 1.
-</details>
diff --git a/problems/largest-values-from-labels/README.md b/problems/largest-values-from-labels/README.md
deleted file mode 100644
index b29a41655..000000000
--- a/problems/largest-values-from-labels/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../duplicate-zeros "Duplicate Zeros")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-path-in-binary-matrix "Shortest Path in Binary Matrix")
-
-## [1090. Largest Values From Labels (Medium)](https://leetcode.com/problems/largest-values-from-labels "受标签影响的最大值")
-
-<p>There is a set of <code>n</code> items. You are given two integer arrays <code>values</code> and <code>labels</code> where the value and the label of the <code>i<sup>th</sup></code> element are <code>values[i]</code> and <code>labels[i]</code> respectively. You are also given two integers <code>numWanted</code> and <code>useLimit</code>.</p>
-
-<p>Choose a subset <code>s</code> of the <code>n</code> elements such that:</p>
-
-<ul>
-	<li>The size of the subset <code>s</code> is <strong>less than or equal to</strong> <code>numWanted</code>.</li>
-	<li>There are <strong>at most</strong> <code>useLimit</code> items with the same label in <code>s</code>.</li>
-</ul>
-
-<p>The <strong>score</strong> of a subset is the sum of the values in the subset.</p>
-
-<p>Return <em>the maximum <strong>score</strong> of a subset </em><code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> values = [5,4,3,2,1], labels = [1,1,2,2,3], numWanted = 3, useLimit = 1
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> The subset chosen is the first, third, and fifth items.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> values = [5,4,3,2,1], labels = [1,3,3,3,2], numWanted = 3, useLimit = 2
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> The subset chosen is the first, second, and third items.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> values = [9,8,8,7,6], labels = [0,0,0,1,1], numWanted = 3, useLimit = 1
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> The subset chosen is the first and fourth items.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> values = [9,8,8,7,6], labels = [0,0,0,1,1], numWanted = 3, useLimit = 2
-<strong>Output:</strong> 24
-<strong>Explanation:</strong> The subset chosen is the first, second, and fourth items.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == values.length == labels.length</code></li>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= values[i], labels[i] &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= numWanted, useLimit &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider the items in order from largest to smallest value, and greedily take the items if they fall under the use_limit.  We can keep track of how many items of each label are used by using a hash table.
-</details>
diff --git a/problems/largest-values-from-labels/largest_values_from_labels.go b/problems/largest-values-from-labels/largest_values_from_labels.go
deleted file mode 100644
index 01d937a95..000000000
--- a/problems/largest-values-from-labels/largest_values_from_labels.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem1090
-
-import "sort"
-
-func largestValsFromLabels(values []int, labels []int, num_wanted int, use_limit int) int {
-	for i, v := range values {
-		values[i] = v<<16 + labels[i]
-	}
-
-	sort.Slice(values, func(i int, j int) bool {
-		return values[i] > values[j]
-	})
-
-	count := [20001]int{}
-	res := 0
-	for _, v := range values {
-		if count[v&0xFFFF] == use_limit {
-			continue
-		}
-		res += v >> 16
-		count[v&0xFFFF]++
-		num_wanted--
-		if num_wanted == 0 {
-			break
-		}
-	}
-
-	return res
-}
diff --git a/problems/last-day-where-you-can-still-cross/README.md b/problems/last-day-where-you-can-still-cross/README.md
deleted file mode 100644
index fbaecbd9f..000000000
--- a/problems/last-day-where-you-can-still-cross/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-non-zero-product-of-the-array-elements "Minimum Non-Zero Product of the Array Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../find-if-path-exists-in-graph "Find if Path Exists in Graph")
-
-## [1970. Last Day Where You Can Still Cross (Hard)](https://leetcode.com/problems/last-day-where-you-can-still-cross "你能穿过矩阵的最后一天")
-
-<p>There is a <strong>1-based</strong> binary matrix where <code>0</code> represents land and <code>1</code> represents water. You are given integers <code>row</code> and <code>col</code> representing the number of rows and columns in the matrix, respectively.</p>
-
-<p>Initially on day <code>0</code>, the <strong>entire</strong> matrix is <strong>land</strong>. However, each day a new cell becomes flooded with <strong>water</strong>. You are given a <strong>1-based</strong> 2D array <code>cells</code>, where <code>cells[i] = [r<sub>i</sub>, c<sub>i</sub>]</code> represents that on the <code>i<sup>th</sup></code> day, the cell on the <code>r<sub>i</sub><sup>th</sup></code> row and <code>c<sub>i</sub><sup>th</sup></code> column (<strong>1-based</strong> coordinates) will be covered with <strong>water</strong> (i.e., changed to <code>1</code>).</p>
-
-<p>You want to find the <strong>last</strong> day that it is possible to walk from the <strong>top</strong> to the <strong>bottom</strong> by only walking on land cells. You can start from <strong>any</strong> cell in the top row and end at <strong>any</strong> cell in the bottom row. You can only travel in the<strong> four</strong> cardinal directions (left, right, up, and down).</p>
-
-<p>Return <em>the <strong>last</strong> day where it is possible to walk from the <strong>top</strong> to the <strong>bottom</strong> by only walking on land cells</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/27/1.png" style="width: 624px; height: 162px;" />
-<pre>
-<strong>Input:</strong> row = 2, col = 2, cells = [[1,1],[2,1],[1,2],[2,2]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The above image depicts how the matrix changes each day starting from day 0.
-The last day where it is possible to cross from top to bottom is on day 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/27/2.png" style="width: 504px; height: 178px;" />
-<pre>
-<strong>Input:</strong> row = 2, col = 2, cells = [[1,1],[1,2],[2,1],[2,2]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The above image depicts how the matrix changes each day starting from day 0.
-The last day where it is possible to cross from top to bottom is on day 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/27/3.png" style="width: 666px; height: 167px;" />
-<pre>
-<strong>Input:</strong> row = 3, col = 3, cells = [[1,2],[2,1],[3,3],[2,2],[1,1],[1,3],[2,3],[3,2],[3,1]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The above image depicts how the matrix changes each day starting from day 0.
-The last day where it is possible to cross from top to bottom is on day 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= row, col &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>4 &lt;= row * col &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>cells.length == row * col</code></li>
-	<li><code>1 &lt;= r<sub>i</sub> &lt;= row</code></li>
-	<li><code>1 &lt;= c<sub>i</sub> &lt;= col</code></li>
-	<li>All the values of <code>cells</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What graph algorithm allows us to find whether a path exists?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use binary search to help us solve the problem?
-</details>
diff --git a/problems/last-moment-before-all-ants-fall-out-of-a-plank/README.md b/problems/last-moment-before-all-ants-fall-out-of-a-plank/README.md
deleted file mode 100644
index 4c259e38a..000000000
--- a/problems/last-moment-before-all-ants-fall-out-of-a-plank/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../can-make-arithmetic-progression-from-sequence "Can Make Arithmetic Progression From Sequence")
-　　　　　　　　　　　　　　　　
-[Next >](../count-submatrices-with-all-ones "Count Submatrices With All Ones")
-
-## [1503. Last Moment Before All Ants Fall Out of a Plank (Medium)](https://leetcode.com/problems/last-moment-before-all-ants-fall-out-of-a-plank "所有蚂蚁掉下来前的最后一刻")
-
-<p>We have a wooden plank of the length <code>n</code> <strong>units</strong>. Some ants are walking on the plank, each ant moves with a speed of <strong>1 unit per second</strong>. Some of the ants move to the <strong>left</strong>, the other move to the <strong>right</strong>.</p>
-
-<p>When two ants moving in two <strong>different</strong> directions meet at some point, they change their directions and continue moving again. Assume changing directions does not take any additional time.</p>
-
-<p>When an ant reaches <strong>one end</strong> of the plank at a time <code>t</code>, it falls out of the plank immediately.</p>
-
-<p>Given an integer <code>n</code> and two integer arrays <code>left</code> and <code>right</code>, the positions of the ants moving to the left and the right, return <em>the moment when the last ant(s) fall out of the plank</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/17/ants.jpg" style="width: 450px; height: 610px;" />
-<pre>
-<strong>Input:</strong> n = 4, left = [4,3], right = [0,1]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> In the image above:
--The ant at index 0 is named A and going to the right.
--The ant at index 1 is named B and going to the right.
--The ant at index 3 is named C and going to the left.
--The ant at index 4 is named D and going to the left.
-The last moment when an ant was on the plank is t = 4 seconds. After that, it falls immediately out of the plank. (i.e., We can say that at t = 4.0000000001, there are no ants on the plank).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/17/ants2.jpg" style="width: 639px; height: 101px;" />
-<pre>
-<strong>Input:</strong> n = 7, left = [], right = [0,1,2,3,4,5,6,7]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> All ants are going to the right, the ant at index 0 needs 7 seconds to fall.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/17/ants3.jpg" style="width: 639px; height: 100px;" />
-<pre>
-<strong>Input:</strong> n = 7, left = [0,1,2,3,4,5,6,7], right = []
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> All ants are going to the left, the ant at index 7 needs 7 seconds to fall.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= left.length &lt;= n + 1</code></li>
-	<li><code>0 &lt;= left[i] &lt;= n</code></li>
-	<li><code>0 &lt;= right.length &lt;= n + 1</code></li>
-	<li><code>0 &lt;= right[i] &lt;= n</code></li>
-	<li><code>1 &lt;= left.length + right.length &lt;= n + 1</code></li>
-	<li>All values of <code>left</code> and <code>right</code> are unique, and each value can appear <strong>only in one</strong> of the two arrays.</li>
-</ul>
-
-### Related Topics
-  [[Brainteaser](../../tag/brainteaser/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The ants change their way when they meet is equivalent to continue moving without changing their direction.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Answer is the max distance for one ant to reach the end of the plank in the facing direction.
-</details>
diff --git a/problems/last-person-to-fit-in-the-bus/README.md b/problems/last-person-to-fit-in-the-bus/README.md
deleted file mode 100644
index 68645ff52..000000000
--- a/problems/last-person-to-fit-in-the-bus/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-items-by-groups-respecting-dependencies "Sort Items by Groups Respecting Dependencies")
-　　　　　　　　　　　　　　　　
-[Next >](../monthly-transactions-ii "Monthly Transactions II")
-
-## [1204. Last Person to Fit in the Bus (Medium)](https://leetcode.com/problems/last-person-to-fit-in-the-bus "最后一个能进入电梯的人")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/last-person-to-fit-in-the-bus/mysql_schemas.sql b/problems/last-person-to-fit-in-the-bus/mysql_schemas.sql
deleted file mode 100644
index fe75f3b5b..000000000
--- a/problems/last-person-to-fit-in-the-bus/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Queue (person_id int, person_name varchar(30), weight int, turn int);
-Truncate table Queue;
-insert into Queue (person_id, person_name, weight, turn) values ('5', 'Alice', '250', '1');
-insert into Queue (person_id, person_name, weight, turn) values ('4', 'Bob', '175', '5');
-insert into Queue (person_id, person_name, weight, turn) values ('3', 'Alex', '350', '2');
-insert into Queue (person_id, person_name, weight, turn) values ('6', 'John Cena', '400', '3');
-insert into Queue (person_id, person_name, weight, turn) values ('1', 'Winston', '500', '6');
-insert into Queue (person_id, person_name, weight, turn) values ('2', 'Marie', '200', '4');
diff --git a/problems/last-person-to-fit-in-the-elevator/README.md b/problems/last-person-to-fit-in-the-elevator/README.md
deleted file mode 100644
index 0d8f8558c..000000000
--- a/problems/last-person-to-fit-in-the-elevator/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-items-by-groups-respecting-dependencies "Sort Items by Groups Respecting Dependencies")
-　　　　　　　　　　　　　　　　
-[Next >](../monthly-transactions-ii "Monthly Transactions II")
-
-## [1204. Last Person to Fit in the Elevator (Medium)](https://leetcode.com/problems/last-person-to-fit-in-the-elevator "最后一个能进入电梯的人")
-
-<p>Table: <code>Queue</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| person_id   | int     |
-| person_name | varchar |
-| weight      | int     |
-| turn        | int     |
-+-------------+---------+
-person_id is the primary key column for this table.
-This table has the information about all people waiting for an elevator.
-The <code>person_id</code>&nbsp;and <code>turn</code> columns will contain all numbers from 1 to n, where n is the number of rows in the table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>The maximum weight the elevator can hold is <strong>1000</strong>.</p>
-
-<p>Write an SQL query to find the&nbsp;<code>person_name</code> of the last person who will fit in the elevator without exceeding the weight limit. It is guaranteed that the person who is&nbsp;first in the queue can fit in the elevator.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Queue table
-+-----------+-------------------+--------+------+
-| person_id | person_name       | weight | turn |
-+-----------+-------------------+--------+------+
-| 5         | George Washington | 250    | 1    |
-| 3         | John Adams        | 350    | 2    |
-| 6         | Thomas Jefferson  | 400    | 3    |
-| 2         | Will Johnliams    | 200    | 4    |
-| 4         | Thomas Jefferson  | 175    | 5    |
-| 1         | James Elephant    | 500    | 6    |
-+-----------+-------------------+--------+------+
-
-Result table
-+-------------------+
-| person_name       |
-+-------------------+
-| Thomas Jefferson  |
-+-------------------+
-
-Queue table is ordered by turn in the example for simplicity.
-In the example George Washington(id 5), John Adams(id 3) and Thomas Jefferson(id 6) will enter the elevator as their weight sum is 250 + 350 + 400 = 1000.
-Thomas Jefferson(id 6) is the last person to fit in the elevator because he has the last turn in these three people.
-</pre>
diff --git a/problems/last-person-to-fit-in-the-elevator/mysql_schemas.sql b/problems/last-person-to-fit-in-the-elevator/mysql_schemas.sql
deleted file mode 100644
index b7a7492a1..000000000
--- a/problems/last-person-to-fit-in-the-elevator/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Queue (person_id int, person_name varchar(30), weight int, turn int);
-Truncate table Queue;
-insert into Queue (person_id, person_name, weight, turn) values ('5', 'George Washington', '250', '1');
-insert into Queue (person_id, person_name, weight, turn) values ('4', 'Thomas Jefferson', '175', '5');
-insert into Queue (person_id, person_name, weight, turn) values ('3', 'John Adams', '350', '2');
-insert into Queue (person_id, person_name, weight, turn) values ('6', 'Thomas Jefferson', '400', '3');
-insert into Queue (person_id, person_name, weight, turn) values ('1', 'James Elephant', '500', '6');
-insert into Queue (person_id, person_name, weight, turn) values ('2', 'Will Johnliams', '200', '4');
diff --git a/problems/last-stone-weight-ii/README.md b/problems/last-stone-weight-ii/README.md
deleted file mode 100644
index 6a41ec950..000000000
--- a/problems/last-stone-weight-ii/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-string-chain "Longest String Chain")
-　　　　　　　　　　　　　　　　
-[Next >](../actors-and-directors-who-cooperated-at-least-three-times "Actors and Directors Who Cooperated At Least Three Times")
-
-## [1049. Last Stone Weight II (Medium)](https://leetcode.com/problems/last-stone-weight-ii "最后一块石头的重量 II")
-
-<p>You are given an array of integers <code>stones</code> where <code>stones[i]</code> is the weight of the <code>i<sup>th</sup></code> stone.</p>
-
-<p>We are playing a game with the stones. On each turn, we choose any two stones and smash them together. Suppose the stones have weights <code>x</code> and <code>y</code> with <code>x &lt;= y</code>. The result of this smash is:</p>
-
-<ul>
-	<li>If <code>x == y</code>, both stones are destroyed, and</li>
-	<li>If <code>x != y</code>, the stone of weight <code>x</code> is destroyed, and the stone of weight <code>y</code> has new weight <code>y - x</code>.</li>
-</ul>
-
-<p>At the end of the game, there is <strong>at most one</strong> stone left.</p>
-
-<p>Return <em>the smallest possible weight of the left stone</em>. If there are no stones left, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [2,7,4,1,8,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-We can combine 2 and 4 to get 2, so the array converts to [2,7,1,8,1] then,
-we can combine 7 and 8 to get 1, so the array converts to [2,1,1,1] then,
-we can combine 2 and 1 to get 1, so the array converts to [1,1,1] then,
-we can combine 1 and 1 to get 0, so the array converts to [1], then that&#39;s the optimal value.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [31,26,33,21,40]
-<strong>Output:</strong> 5
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [1,2]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= stones.length &lt;= 30</code></li>
-	<li><code>1 &lt;= stones[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think of the final answer as a sum of weights with + or - sign symbols infront of each weight.  Actually, all sums with 1 of each sign symbol are possible.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use dynamic programming: for every possible sum with N stones, those sums +x or -x is possible with N+1 stones, where x is the value of the newest stone.  (This overcounts sums that are all positive or all negative, but those don't matter.)
-</details>
diff --git a/problems/last-stone-weight-ii/last_stone_weight_ii.go b/problems/last-stone-weight-ii/last_stone_weight_ii.go
deleted file mode 100644
index 483039d37..000000000
--- a/problems/last-stone-weight-ii/last_stone_weight_ii.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem1049
-
-func lastStoneWeightII(stones []int) int {
-	hasSum := [3001]bool{}
-	hasSum[0] = true
-	sum := 0
-	for _, s := range stones {
-		sum += s
-		for i := sum; i >= s; i-- {
-			// record all sum of any choose form stones
-			hasSum[i] = hasSum[i] || hasSum[i-s]
-		}
-	}
-	// now, sum is sum(stones)
-	// take stones to two group，weights are part and sum-part
-	// result is sum-part - part
-	// best is part = sum/2
-	// if not, check part--
-	// until part = 0
-	part := sum / 2
-	for part >= 0 && !hasSum[part] {
-		part--
-	}
-	return sum - part - part
-}
diff --git a/problems/last-stone-weight/README.md b/problems/last-stone-weight/README.md
deleted file mode 100644
index 781736daf..000000000
--- a/problems/last-stone-weight/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../customers-who-bought-all-products "Customers Who Bought All Products")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-all-adjacent-duplicates-in-string "Remove All Adjacent Duplicates In String")
-
-## [1046. Last Stone Weight (Easy)](https://leetcode.com/problems/last-stone-weight "最后一块石头的重量")
-
-<p>You are given an array of integers <code>stones</code> where <code>stones[i]</code> is the weight of the <code>i<sup>th</sup></code> stone.</p>
-
-<p>We are playing a game with the stones. On each turn, we choose the <strong>heaviest two stones</strong> and smash them together. Suppose the heaviest two stones have weights <code>x</code> and <code>y</code> with <code>x &lt;= y</code>. The result of this smash is:</p>
-
-<ul>
-	<li>If <code>x == y</code>, both stones are destroyed, and</li>
-	<li>If <code>x != y</code>, the stone of weight <code>x</code> is destroyed, and the stone of weight <code>y</code> has new weight <code>y - x</code>.</li>
-</ul>
-
-<p>At the end of the game, there is <strong>at most one</strong> stone left.</p>
-
-<p>Return <em>the smallest possible weight of the left stone</em>. If there are no stones left, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [2,7,4,1,8,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 
-We combine 7 and 8 to get 1 so the array converts to [2,4,1,1,1] then,
-we combine 2 and 4 to get 2 so the array converts to [2,1,1,1] then,
-we combine 2 and 1 to get 1 so the array converts to [1,1,1] then,
-we combine 1 and 1 to get 0 so the array converts to [1] then that&#39;s the value of the last stone.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [1]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= stones.length &lt;= 30</code></li>
-	<li><code>1 &lt;= stones[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process.  We can do it with a heap, or by sorting some list of stones every time we take a turn.
-</details>
diff --git a/problems/last-stone-weight/last_stone_weight.go b/problems/last-stone-weight/last_stone_weight.go
deleted file mode 100644
index b063ccc4a..000000000
--- a/problems/last-stone-weight/last_stone_weight.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem1046
-
-import "sort"
-
-func lastStoneWeight(stones []int) int {
-	for len(stones) >= 2 {
-		n := len(stones) - 1
-		sort.Ints(stones)
-		v := stones[n] - stones[n-1]
-		if v > 0 {
-			stones[n-1] = v
-		} else {
-			n--
-		}
-		stones = stones[:n]
-	}
-	stones = append(stones, 0)
-	return stones[0]
-}
diff --git a/problems/last-stone-weight/last_stone_weight_test.go b/problems/last-stone-weight/last_stone_weight_test.go
deleted file mode 100644
index 413f1d538..000000000
--- a/problems/last-stone-weight/last_stone_weight_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem1046
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestLastStoneWeight(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{2, 7, 4, 1, 8, 1},
-			want: 1,
-		},
-		{
-			in:   []int{2, 7, 4, 1, 8, 1, 5},
-			want: 0,
-		},
-		{
-			in:   []int{316, 157, 73, 106, 771, 828},
-			want: 37,
-		},
-	}
-	for _, tt := range tests {
-		got := lastStoneWeight(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/last-substring-in-lexicographical-order/README.md b/problems/last-substring-in-lexicographical-order/README.md
deleted file mode 100644
index a0a54cd2d..000000000
--- a/problems/last-substring-in-lexicographical-order/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../as-far-from-land-as-possible "As Far from Land as Possible")
-　　　　　　　　　　　　　　　　
-[Next >](../product-price-at-a-given-date "Product Price at a Given Date")
-
-## [1163. Last Substring in Lexicographical Order (Hard)](https://leetcode.com/problems/last-substring-in-lexicographical-order "按字典序排在最后的子串")
-
-<p>Given a string <code>s</code>, return <em>the last substring of</em> <code>s</code> <em>in lexicographical order</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abab&quot;
-<strong>Output:</strong> &quot;bab&quot;
-<strong>Explanation:</strong> The substrings are [&quot;a&quot;, &quot;ab&quot;, &quot;aba&quot;, &quot;abab&quot;, &quot;b&quot;, &quot;ba&quot;, &quot;bab&quot;]. The lexicographically maximum substring is &quot;bab&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;
-<strong>Output:</strong> &quot;tcode&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 4 * 10<sup>5</sup></code></li>
-	<li><code>s</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Assume that the answer is a sub-string from index i to j. If you add the character at index j+1 you get a better answer.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The answer is always a suffix of the given string.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Since the limits are high, we need an efficient data structure.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use suffix array.
-</details>
diff --git a/problems/last-substring-in-lexicographical-order/last_substring_in_lexicographical_order.go b/problems/last-substring-in-lexicographical-order/last_substring_in_lexicographical_order.go
deleted file mode 100644
index e20879500..000000000
--- a/problems/last-substring-in-lexicographical-order/last_substring_in_lexicographical_order.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem1163
-
-func lastSubstring(s string) string {
-	last, n := 0, len(s)
-	for i := 1; i < n; i++ {
-		if s[i-1] == s[i] {
-			// all of s[last:i+1] are the same letter.
-			// 'i' has no chance to be the new 'last'
-			// the reason is
-			// 1. s[i+1] > s[i], 'i+1' is the new 'last'
-			// 2. s[i+1] < s[i], 'last' is still 'last'
-			// 3. s[i+1] = s[i], 'i+1' is the new 'i'
-			// like above, need a different letter to make decision
-			continue
-		}
-		for l := 0; i+l < n; l++ {
-			if s[last+l] < s[i+l] {
-				// s[i:] is bigger than s[last:]
-				// new begin is here
-				last = i
-				break
-			}
-			if s[last+l] > s[i+l] {
-				// s[last:] is bigger than s[i:]
-				// no need to compare continue
-				break
-			}
-		}
-	}
-	return s[last:]
-}
diff --git a/problems/last-substring-in-lexicographical-order/last_substring_in_lexicographical_order_test.go b/problems/last-substring-in-lexicographical-order/last_substring_in_lexicographical_order_test.go
deleted file mode 100644
index 1e78a9171..000000000
--- a/problems/last-substring-in-lexicographical-order/last_substring_in_lexicographical_order_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1163
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestLastSubstring(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "abab",
-			want: "bab",
-		},
-		{
-			in:   "abcdabc",
-			want: "dabc",
-		},
-		{
-			in:   "ffbcdfeda",
-			want: "ffbcdfeda",
-		},
-		{
-			in:   "hksljkjsfjv",
-			want: "v",
-		},
-	}
-	for _, tt := range tests {
-		got := lastSubstring(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/latest-time-by-replacing-hidden-digits/README.md b/problems/latest-time-by-replacing-hidden-digits/README.md
deleted file mode 100644
index 1410e84f9..000000000
--- a/problems/latest-time-by-replacing-hidden-digits/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-ways-to-make-array-with-product "Count Ways to Make Array With Product")
-　　　　　　　　　　　　　　　　
-[Next >](../change-minimum-characters-to-satisfy-one-of-three-conditions "Change Minimum Characters to Satisfy One of Three Conditions")
-
-## [1736. Latest Time by Replacing Hidden Digits (Easy)](https://leetcode.com/problems/latest-time-by-replacing-hidden-digits "替换隐藏数字得到的最晚时间")
-
-<p>You are given a string <code>time</code> in the form of <code> hh:mm</code>, where some of the digits in the string are hidden (represented by <code>?</code>).</p>
-
-<p>The valid times are those inclusively between <code>00:00</code> and <code>23:59</code>.</p>
-
-<p>Return <em>the latest valid time you can get from</em> <code>time</code><em> by replacing the hidden</em> <em>digits</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> time = &quot;2?:?0&quot;
-<strong>Output:</strong> &quot;23:50&quot;
-<strong>Explanation:</strong> The latest hour beginning with the digit &#39;2&#39; is 23 and the latest minute ending with the digit &#39;0&#39; is 50.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> time = &quot;0?:3?&quot;
-<strong>Output:</strong> &quot;09:39&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> time = &quot;1?:22&quot;
-<strong>Output:</strong> &quot;19:22&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>time</code> is in the format <code>hh:mm</code>.</li>
-	<li>It is guaranteed that you can produce a valid time from the given string.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Trying out all possible solutions from biggest to smallest would fit in the time limit.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To check if the solution is okay, you need to find out if it's valid and matches every character
-</details>
diff --git a/problems/leaf-similar-trees/README.md b/problems/leaf-similar-trees/README.md
deleted file mode 100644
index 38ce2a321..000000000
--- a/problems/leaf-similar-trees/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-refueling-stops "Minimum Number of Refueling Stops")
-　　　　　　　　　　　　　　　　
-[Next >](../length-of-longest-fibonacci-subsequence "Length of Longest Fibonacci Subsequence")
-
-## [872. Leaf-Similar Trees (Easy)](https://leetcode.com/problems/leaf-similar-trees "叶子相似的树")
-
-<p>Consider all the leaves of a binary tree, from&nbsp;left to right order, the values of those&nbsp;leaves form a <strong>leaf value sequence</strong><em>.</em></p>
-
-<p><img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/07/16/tree.png" style="width: 400px; height: 336px;" /></p>
-
-<p>For example, in the given tree above, the leaf value sequence is <code>(6, 7, 4, 9, 8)</code>.</p>
-
-<p>Two binary trees are considered <em>leaf-similar</em>&nbsp;if their leaf value sequence is the same.</p>
-
-<p>Return <code>true</code> if and only if the two given trees with head nodes <code>root1</code> and <code>root2</code> are leaf-similar.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/03/leaf-similar-1.jpg" style="width: 750px; height: 297px;" />
-<pre>
-<strong>Input:</strong> root1 = [3,5,1,6,2,9,8,null,null,7,4], root2 = [3,5,1,6,7,4,2,null,null,null,null,null,null,9,8]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root1 = [1], root2 = [1]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root1 = [1], root2 = [2]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> root1 = [1,2], root2 = [2,2]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 5:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/03/leaf-similar-2.jpg" style="width: 450px; height: 165px;" />
-<pre>
-<strong>Input:</strong> root1 = [1,2,3], root2 = [1,3,2]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in each tree will be in the range <code>[1, 200]</code>.</li>
-	<li>Both of the given trees will have values in the range <code>[0, 200]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/leaf-similar-trees/leaf_similar_trees.go b/problems/leaf-similar-trees/leaf_similar_trees.go
deleted file mode 100644
index 1857971cf..000000000
--- a/problems/leaf-similar-trees/leaf_similar_trees.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem872
diff --git a/problems/leaf-similar-trees/leaf_similar_trees_test.go b/problems/leaf-similar-trees/leaf_similar_trees_test.go
deleted file mode 100644
index 1857971cf..000000000
--- a/problems/leaf-similar-trees/leaf_similar_trees_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem872
diff --git a/problems/league-statistics/README.md b/problems/league-statistics/README.md
deleted file mode 100644
index 30c677001..000000000
--- a/problems/league-statistics/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-building-height "Maximum Building Height")
-　　　　　　　　　　　　　　　　
-[Next >](../next-palindrome-using-same-digits "Next Palindrome Using Same Digits")
-
-## [1841. League Statistics (Medium)](https://leetcode.com/problems/league-statistics "联赛信息统计")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/league-statistics/mysql_schemas.sql b/problems/league-statistics/mysql_schemas.sql
deleted file mode 100644
index 0f6c35b2b..000000000
--- a/problems/league-statistics/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Teams (team_id int, team_name varchar(20));
-Create table If Not Exists Matches (home_team_id int, away_team_id int, home_team_goals int, away_team_goals int);
-Truncate table Teams;
-insert into Teams (team_id, team_name) values ('1', 'Ajax');
-insert into Teams (team_id, team_name) values ('4', 'Dortmund');
-insert into Teams (team_id, team_name) values ('6', 'Arsenal');
-Truncate table Matches;
-insert into Matches (home_team_id, away_team_id, home_team_goals, away_team_goals) values ('1', '4', '0', '1');
-insert into Matches (home_team_id, away_team_id, home_team_goals, away_team_goals) values ('1', '6', '3', '3');
-insert into Matches (home_team_id, away_team_id, home_team_goals, away_team_goals) values ('4', '1', '5', '2');
-insert into Matches (home_team_id, away_team_id, home_team_goals, away_team_goals) values ('6', '1', '0', '0');
diff --git a/problems/least-number-of-unique-integers-after-k-removals/README.md b/problems/least-number-of-unique-integers-after-k-removals/README.md
deleted file mode 100644
index 07b4b71a6..000000000
--- a/problems/least-number-of-unique-integers-after-k-removals/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../running-sum-of-1d-array "Running Sum of 1d Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-days-to-make-m-bouquets "Minimum Number of Days to Make m Bouquets")
-
-## [1481. Least Number of Unique Integers after K Removals (Medium)](https://leetcode.com/problems/least-number-of-unique-integers-after-k-removals "不同整数的最少数目")
-
-<p>Given an array of integers&nbsp;<code>arr</code>&nbsp;and an integer <code>k</code>.&nbsp;Find the <em>least number of unique integers</em>&nbsp;after removing <strong>exactly</strong> <code>k</code> elements<b>.</b></p>
-
-<ol>
-</ol>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>arr = [5,5,4], k = 1
-<strong>Output: </strong>1
-<strong>Explanation</strong>: Remove the single 4, only 5 is left.
-</pre>
-<strong>Example 2:</strong>
-
-<pre>
-<strong>Input: </strong>arr = [4,3,1,1,3,3,2], k = 3
-<strong>Output: </strong>2
-<strong>Explanation</strong>: Remove 4, 2 and either one of the two 1s or three 3s. 1 and 3 will be left.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length&nbsp;&lt;= 10^5</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10^9</code></li>
-	<li><code>0 &lt;= k&nbsp;&lt;= arr.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a map to count the frequencies of the numbers in the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-An optimal strategy is to remove the numbers with the smallest count first.
-</details>
diff --git a/problems/least-operators-to-express-number/README.md b/problems/least-operators-to-express-number/README.md
deleted file mode 100644
index b66220e68..000000000
--- a/problems/least-operators-to-express-number/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-area-rectangle-ii "Minimum Area Rectangle II")
-　　　　　　　　　　　　　　　　
-[Next >](../univalued-binary-tree "Univalued Binary Tree")
-
-## [964. Least Operators to Express Number (Hard)](https://leetcode.com/problems/least-operators-to-express-number "表示数字的最少运算符")
-
-<p>Given a single positive integer <code>x</code>, we will write an expression of the form <code>x (op1) x (op2) x (op3) x ...</code> where each operator <code>op1</code>, <code>op2</code>, etc. is either addition, subtraction, multiplication, or division (<code>+</code>, <code>-</code>, <code>*</code>, or <code>/)</code>. For example, with <code>x = 3</code>, we might write <code>3 * 3 / 3 + 3 - 3</code> which is a value of <font face="monospace">3</font>.</p>
-
-<p>When writing such an expression, we adhere to the following conventions:</p>
-
-<ul>
-	<li>The division operator (<code>/</code>) returns rational numbers.</li>
-	<li>There are no parentheses placed anywhere.</li>
-	<li>We use the usual order of operations: multiplication and division happen before addition and subtraction.</li>
-	<li>It is not allowed to use the unary negation operator (<code>-</code>). For example, &quot;<code>x - x</code>&quot; is a valid expression as it only uses subtraction, but &quot;<code>-x + x</code>&quot; is not because it uses negation.</li>
-</ul>
-
-<p>We would like to write an expression with the least number of operators such that the expression equals the given <code>target</code>. Return the least number of operators used.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 3, target = 19
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> 3 * 3 + 3 * 3 + 3 / 3.
-The expression contains 5 operations.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 5, target = 501
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> 5 * 5 * 5 * 5 - 5 * 5 * 5 + 5 / 5.
-The expression contains 8 operations.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 100, target = 100000000
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 100 * 100 * 100 * 100.
-The expression contains 3 operations.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= x &lt;= 100</code></li>
-	<li><code>1 &lt;= target &lt;= 2 * 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/least-operators-to-express-number/least_operators_to_express_number.go b/problems/least-operators-to-express-number/least_operators_to_express_number.go
deleted file mode 100644
index 47932d06d..000000000
--- a/problems/least-operators-to-express-number/least_operators_to_express_number.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem964
-
-func leastOpsExpressTarget(x int, target int) int {
-	return 0
-}
diff --git a/problems/leetcodify-friends-recommendations/README.md b/problems/leetcodify-friends-recommendations/README.md
deleted file mode 100644
index dcc682953..000000000
--- a/problems/leetcodify-friends-recommendations/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-ways-to-build-rooms-in-an-ant-colony "Count Ways to Build Rooms in an Ant Colony")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-smallest-subarray-sum "Kth Smallest Subarray Sum")
-
-## [1917. Leetcodify Friends Recommendations (Hard)](https://leetcode.com/problems/leetcodify-friends-recommendations "Leetcodify 好友推荐")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/leetcodify-friends-recommendations/mysql_schemas.sql b/problems/leetcodify-friends-recommendations/mysql_schemas.sql
deleted file mode 100644
index d991fe675..000000000
--- a/problems/leetcodify-friends-recommendations/mysql_schemas.sql
+++ /dev/null
@@ -1,20 +0,0 @@
-Create table If Not Exists Listens (user_id int, song_id int, day date);
-Create table If Not Exists Friendship (user1_id int, user2_id int);
-Truncate table Listens;
-insert into Listens (user_id, song_id, day) values ('1', '10', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('1', '11', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('1', '12', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('2', '10', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('2', '11', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('2', '12', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('3', '10', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('3', '11', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('3', '12', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('4', '10', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('4', '11', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('4', '13', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('5', '10', '2021-03-16');
-insert into Listens (user_id, song_id, day) values ('5', '11', '2021-03-16');
-insert into Listens (user_id, song_id, day) values ('5', '12', '2021-03-16');
-Truncate table Friendship;
-insert into Friendship (user1_id, user2_id) values ('1', '2');
diff --git a/problems/leetcodify-similar-friends/README.md b/problems/leetcodify-similar-friends/README.md
deleted file mode 100644
index 3d20773a3..000000000
--- a/problems/leetcodify-similar-friends/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-smallest-subarray-sum "Kth Smallest Subarray Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../build-array-from-permutation "Build Array from Permutation")
-
-## [1919. Leetcodify Similar Friends (Hard)](https://leetcode.com/problems/leetcodify-similar-friends "兴趣相同的朋友")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Leetcodify Friends Recommendations](../leetcodify-friends-recommendations) (Hard)
diff --git a/problems/leetcodify-similar-friends/mysql_schemas.sql b/problems/leetcodify-similar-friends/mysql_schemas.sql
deleted file mode 100644
index a1c1de591..000000000
--- a/problems/leetcodify-similar-friends/mysql_schemas.sql
+++ /dev/null
@@ -1,22 +0,0 @@
-Create table If Not Exists Listens (user_id int, song_id int, day date);
-Create table If Not Exists Friendship (user1_id int, user2_id int);
-Truncate table Listens;
-insert into Listens (user_id, song_id, day) values ('1', '10', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('1', '11', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('1', '12', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('2', '10', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('2', '11', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('2', '12', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('3', '10', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('3', '11', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('3', '12', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('4', '10', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('4', '11', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('4', '13', '2021-03-15');
-insert into Listens (user_id, song_id, day) values ('5', '10', '2021-03-16');
-insert into Listens (user_id, song_id, day) values ('5', '11', '2021-03-16');
-insert into Listens (user_id, song_id, day) values ('5', '12', '2021-03-16');
-Truncate table Friendship;
-insert into Friendship (user1_id, user2_id) values ('1', '2');
-insert into Friendship (user1_id, user2_id) values ('2', '4');
-insert into Friendship (user1_id, user2_id) values ('2', '5');
diff --git a/problems/leetflex-banned-accounts/README.md b/problems/leetflex-banned-accounts/README.md
deleted file mode 100644
index b6c7f5d38..000000000
--- a/problems/leetflex-banned-accounts/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-subarray-sum-after-one-operation "Maximum Subarray Sum After One Operation")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-unique-elements "Sum of Unique Elements")
-
-## [1747. Leetflex Banned Accounts (Medium)](https://leetcode.com/problems/leetflex-banned-accounts "应该被禁止的Leetflex账户")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/leetflex-banned-accounts/mysql_schemas.sql b/problems/leetflex-banned-accounts/mysql_schemas.sql
deleted file mode 100644
index d9f5775c4..000000000
--- a/problems/leetflex-banned-accounts/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists LogInfo (account_id int, ip_address int, login datetime, logout datetime);
-Truncate table LogInfo;
-insert into LogInfo (account_id, ip_address, login, logout) values ('1', '1', '2021-02-01 09:00:00', '2021-02-01 09:30:00');
-insert into LogInfo (account_id, ip_address, login, logout) values ('1', '2', '2021-02-01 08:00:00', '2021-02-01 11:30:00');
-insert into LogInfo (account_id, ip_address, login, logout) values ('2', '6', '2021-02-01 20:30:00', '2021-02-01 22:00:00');
-insert into LogInfo (account_id, ip_address, login, logout) values ('2', '7', '2021-02-02 20:30:00', '2021-02-02 22:00:00');
-insert into LogInfo (account_id, ip_address, login, logout) values ('3', '9', '2021-02-01 16:00:00', '2021-02-01 16:59:59');
-insert into LogInfo (account_id, ip_address, login, logout) values ('3', '13', '2021-02-01 17:00:00', '2021-02-01 17:59:59');
-insert into LogInfo (account_id, ip_address, login, logout) values ('4', '10', '2021-02-01 16:00:00', '2021-02-01 17:00:00');
-insert into LogInfo (account_id, ip_address, login, logout) values ('4', '11', '2021-02-01 17:00:00', '2021-02-01 17:59:59');
diff --git a/problems/leftmost-column-with-at-least-a-one/README.md b/problems/leftmost-column-with-at-least-a-one/README.md
deleted file mode 100644
index da3d04af4..000000000
--- a/problems/leftmost-column-with-at-least-a-one/README.md
+++ /dev/null
@@ -1,31 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../perform-string-shifts "Perform String Shifts")
-　　　　　　　　　　　　　　　　
-[Next >](../first-unique-number "First Unique Number")
-
-## [1428. Leftmost Column with at Least a One (Medium)](https://leetcode.com/problems/leftmost-column-with-at-least-a-one "至少有一个 1 的最左端列")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-1. (Binary Search) For each row do a binary search to find the leftmost one on that row and update the answer.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-2. (Optimal Approach) Imagine there is a pointer p(x, y) starting from top right corner. p can only move left or down. If the value at p is 0, move down. If the value at p is 1, move left. Try to figure out the correctness and time complexity of this algorithm.
-</details>
diff --git a/problems/lemonade-change/README.md b/problems/lemonade-change/README.md
deleted file mode 100644
index 1eb2c1502..000000000
--- a/problems/lemonade-change/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../buddy-strings "Buddy Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../score-after-flipping-matrix "Score After Flipping Matrix")
-
-## [860. Lemonade Change (Easy)](https://leetcode.com/problems/lemonade-change "柠檬水找零")
-
-<p>At a lemonade stand, each lemonade costs <code>$5</code>. Customers are standing in a queue to buy from you, and order one at a time (in the order specified by bills). Each customer will only buy one lemonade and pay with either a <code>$5</code>, <code>$10</code>, or <code>$20</code> bill. You must provide the correct change to each customer so that the net transaction is that the customer pays <code>$5</code>.</p>
-
-<p>Note that you don&#39;t have any change in hand at first.</p>
-
-<p>Given an integer array <code>bills</code> where <code>bills[i]</code> is the bill the <code>i<sup>th</sup></code> customer pays, return <code>true</code> <em>if you can provide every customer with correct change, or</em> <code>false</code> <em>otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> bills = [5,5,5,10,20]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 
-From the first 3 customers, we collect three $5 bills in order.
-From the fourth customer, we collect a $10 bill and give back a $5.
-From the fifth customer, we give a $10 bill and a $5 bill.
-Since all customers got correct change, we output true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> bills = [5,5,10,10,20]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> 
-From the first two customers in order, we collect two $5 bills.
-For the next two customers in order, we collect a $10 bill and give back a $5 bill.
-For the last customer, we can not give change of $15 back because we only have two $10 bills.
-Since not every customer received correct change, the answer is false.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> bills = [5,5,10]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> bills = [10,10]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= bills.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>bills[i]</code> is either <code>5</code>, <code>10</code>, or <code>20</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
diff --git a/problems/lemonade-change/lemonade_change.go b/problems/lemonade-change/lemonade_change.go
deleted file mode 100644
index 86266a10d..000000000
--- a/problems/lemonade-change/lemonade_change.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem860
diff --git a/problems/lemonade-change/lemonade_change_test.go b/problems/lemonade-change/lemonade_change_test.go
deleted file mode 100644
index 86266a10d..000000000
--- a/problems/lemonade-change/lemonade_change_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem860
diff --git a/problems/length-of-last-word/README.md b/problems/length-of-last-word/README.md
deleted file mode 100644
index 5205f2a17..000000000
--- a/problems/length-of-last-word/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../insert-interval "Insert Interval")
-　　　　　　　　　　　　　　　　
-[Next >](../spiral-matrix-ii "Spiral Matrix II")
-
-## [58. Length of Last Word (Easy)](https://leetcode.com/problems/length-of-last-word "最后一个单词的长度")
-
-<p>Given a string <code>s</code> consisting&nbsp;of some words separated by some number of spaces, return <em>the length of the <strong>last</strong> word in the string.</em></p>
-
-<p>A <strong>word</strong> is a maximal substring consisting of non-space characters only.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;Hello World&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The last word is &quot;World&quot; with length 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;   fly me   to   the moon  &quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The last word is &quot;moon&quot; with length 4.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;luffy is still joyboy&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The last word is &quot;joyboy&quot; with length 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of only English letters and spaces <code>&#39; &#39;</code>.</li>
-	<li>There will be at least one word in <code>s</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/length-of-last-word/length_of_last_word.go b/problems/length-of-last-word/length_of_last_word.go
deleted file mode 100644
index 629da54c7..000000000
--- a/problems/length-of-last-word/length_of_last_word.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem58
-
-func lengthOfLastWord(s string) int {
-	wc, l := 0, len(s)-1
-	for i := l; i >= 0; i-- {
-		if s[i] != ' ' {
-			wc++
-		} else if wc > 0 {
-			return wc
-		}
-	}
-	return wc
-}
diff --git a/problems/length-of-last-word/length_of_last_word_test.go b/problems/length-of-last-word/length_of_last_word_test.go
deleted file mode 100644
index 0ce4d9c57..000000000
--- a/problems/length-of-last-word/length_of_last_word_test.go
+++ /dev/null
@@ -1,22 +0,0 @@
-package problem58
-
-import "testing"
-
-func TestLengthOfLastWord(t *testing.T) {
-	tests := map[string]int{
-		"Hello World":      5,
-		"Hello":            5,
-		"this is a string": 6,
-		"":                 0,
-		" ":                0,
-		"a ":               1,
-		"b  ":              1,
-	}
-
-	for in, want := range tests {
-		got := lengthOfLastWord(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/length-of-longest-fibonacci-subsequence/README.md b/problems/length-of-longest-fibonacci-subsequence/README.md
deleted file mode 100644
index fb769902d..000000000
--- a/problems/length-of-longest-fibonacci-subsequence/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../leaf-similar-trees "Leaf-Similar Trees")
-　　　　　　　　　　　　　　　　
-[Next >](../walking-robot-simulation "Walking Robot Simulation")
-
-## [873. Length of Longest Fibonacci Subsequence (Medium)](https://leetcode.com/problems/length-of-longest-fibonacci-subsequence "最长的斐波那契子序列的长度")
-
-<p>A sequence <code>x<sub>1</sub>, x<sub>2</sub>, ..., x<sub>n</sub></code> is <em>Fibonacci-like</em> if:</p>
-
-<ul>
-	<li><code>n &gt;= 3</code></li>
-	<li><code>x<sub>i</sub> + x<sub>i+1</sub> == x<sub>i+2</sub></code> for all <code>i + 2 &lt;= n</code></li>
-</ul>
-
-<p>Given a <b>strictly increasing</b> array <code>arr</code> of positive integers forming a sequence, return <em>the <strong>length</strong> of the longest Fibonacci-like subsequence of</em> <code>arr</code>. If one does not exist, return <code>0</code>.</p>
-
-<p>A <strong>subsequence</strong> is derived from another sequence <code>arr</code> by deleting any number of elements (including none) from <code>arr</code>, without changing the order of the remaining elements. For example, <code>[3, 5, 8]</code> is a subsequence of <code>[3, 4, 5, 6, 7, 8]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4,5,6,7,8]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The longest subsequence that is fibonacci-like: [1,2,3,5,8].</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,3,7,11,12,14,18]
-<strong>Output:</strong> 3
-<strong>Explanation</strong>:<strong> </strong>The longest subsequence that is fibonacci-like: [1,11,12], [3,11,14] or [7,11,18].</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= arr[i] &lt; arr[i + 1] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Fibonacci Number](../fibonacci-number) (Easy)
diff --git a/problems/length-of-longest-fibonacci-subsequence/length_of_longest_fibonacci_subsequence.go b/problems/length-of-longest-fibonacci-subsequence/length_of_longest_fibonacci_subsequence.go
deleted file mode 100644
index fcd5924f8..000000000
--- a/problems/length-of-longest-fibonacci-subsequence/length_of_longest_fibonacci_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem873
diff --git a/problems/length-of-longest-fibonacci-subsequence/length_of_longest_fibonacci_subsequence_test.go b/problems/length-of-longest-fibonacci-subsequence/length_of_longest_fibonacci_subsequence_test.go
deleted file mode 100644
index fcd5924f8..000000000
--- a/problems/length-of-longest-fibonacci-subsequence/length_of_longest_fibonacci_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem873
diff --git a/problems/letter-case-permutation/README.md b/problems/letter-case-permutation/README.md
deleted file mode 100644
index 975c5da62..000000000
--- a/problems/letter-case-permutation/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-distance-between-bst-nodes "Minimum Distance Between BST Nodes")
-　　　　　　　　　　　　　　　　
-[Next >](../is-graph-bipartite "Is Graph Bipartite?")
-
-## [784. Letter Case Permutation (Medium)](https://leetcode.com/problems/letter-case-permutation "字母大小写全排列")
-
-<p>Given a string <code>s</code>, you&nbsp;can transform every letter individually to be lowercase or uppercase to create another string.</p>
-
-<p>Return <em>a list of all possible strings we could create</em>. Return the output in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a1b2&quot;
-<strong>Output:</strong> [&quot;a1b2&quot;,&quot;a1B2&quot;,&quot;A1b2&quot;,&quot;A1B2&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;3z4&quot;
-<strong>Output:</strong> [&quot;3z4&quot;,&quot;3Z4&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 12</code></li>
-	<li><code>s</code> consists of lowercase English letters, uppercase English letters, and digits.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Subsets](../subsets) (Medium)
-  1. [Brace Expansion](../brace-expansion) (Medium)
diff --git a/problems/letter-case-permutation/letter_case_permutation.go b/problems/letter-case-permutation/letter_case_permutation.go
deleted file mode 100644
index 70d1adde2..000000000
--- a/problems/letter-case-permutation/letter_case_permutation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem784
diff --git a/problems/letter-case-permutation/letter_case_permutation_test.go b/problems/letter-case-permutation/letter_case_permutation_test.go
deleted file mode 100644
index 70d1adde2..000000000
--- a/problems/letter-case-permutation/letter_case_permutation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem784
diff --git a/problems/letter-combinations-of-a-phone-number/README.md b/problems/letter-combinations-of-a-phone-number/README.md
deleted file mode 100644
index 9137185d6..000000000
--- a/problems/letter-combinations-of-a-phone-number/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../3sum-closest "3Sum Closest")
-　　　　　　　　　　　　　　　　
-[Next >](../4sum "4Sum")
-
-## [17. Letter Combinations of a Phone Number (Medium)](https://leetcode.com/problems/letter-combinations-of-a-phone-number "电话号码的字母组合")
-
-<p>Given a string containing digits from <code>2-9</code> inclusive, return all possible letter combinations that the number could represent. Return the answer in <strong>any order</strong>.</p>
-
-<p>A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.</p>
-
-<p><img src="https://upload.wikimedia.org/wikipedia/commons/thumb/7/73/Telephone-keypad2.svg/200px-Telephone-keypad2.svg.png" style="width: 200px; height: 162px;" /></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = &quot;23&quot;
-<strong>Output:</strong> [&quot;ad&quot;,&quot;ae&quot;,&quot;af&quot;,&quot;bd&quot;,&quot;be&quot;,&quot;bf&quot;,&quot;cd&quot;,&quot;ce&quot;,&quot;cf&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = &quot;&quot;
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = &quot;2&quot;
-<strong>Output:</strong> [&quot;a&quot;,&quot;b&quot;,&quot;c&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= digits.length &lt;= 4</code></li>
-	<li><code>digits[i]</code> is a digit in the range <code>[&#39;2&#39;, &#39;9&#39;]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Generate Parentheses](../generate-parentheses) (Medium)
-  1. [Combination Sum](../combination-sum) (Medium)
-  1. [Binary Watch](../binary-watch) (Easy)
diff --git a/problems/letter-combinations-of-a-phone-number/letter_combinations_of_a_phone_number.go b/problems/letter-combinations-of-a-phone-number/letter_combinations_of_a_phone_number.go
deleted file mode 100644
index 9262cc8dd..000000000
--- a/problems/letter-combinations-of-a-phone-number/letter_combinations_of_a_phone_number.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem17
-
-func letterCombinations(digits string) []string {
-	if digits == "" {
-		return nil
-	}
-	m := map[rune][]string{
-		'2': {"a", "b", "c"},
-		'3': {"d", "e", "f"},
-		'4': {"g", "h", "i"},
-		'5': {"j", "k", "l"},
-		'6': {"m", "n", "o"},
-		'7': {"p", "q", "r", "s"},
-		'8': {"t", "u", "v"},
-		'9': {"w", "x", "y", "z"},
-	}
-	ans := make([]string, 1)
-	for _, k := range digits {
-		idx, t := 0, make([]string, len(ans))
-		copy(t, ans)
-		for _, s := range t {
-			for _, c := range m[k] {
-				if idx < len(ans) {
-					ans[idx] = s + c
-				} else {
-					ans = append(ans, s+c)
-				}
-				idx++
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/letter-combinations-of-a-phone-number/letter_combinations_of_a_phone_number_test.go b/problems/letter-combinations-of-a-phone-number/letter_combinations_of_a_phone_number_test.go
deleted file mode 100644
index 8f44f3aa3..000000000
--- a/problems/letter-combinations-of-a-phone-number/letter_combinations_of_a_phone_number_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem17
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   string
-	want []string
-}
-
-func TestLetterCombinations(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "",
-			want: nil,
-		},
-		{
-			in:   "23",
-			want: []string{"ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"},
-		},
-	}
-	for _, tt := range tests {
-		got := letterCombinations(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/letter-tile-possibilities/README.md b/problems/letter-tile-possibilities/README.md
deleted file mode 100644
index 1b0f83163..000000000
--- a/problems/letter-tile-possibilities/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../occurrences-after-bigram "Occurrences After Bigram")
-　　　　　　　　　　　　　　　　
-[Next >](../insufficient-nodes-in-root-to-leaf-paths "Insufficient Nodes in Root to Leaf Paths")
-
-## [1079. Letter Tile Possibilities (Medium)](https://leetcode.com/problems/letter-tile-possibilities "活字印刷")
-
-<p>You have <code>n</code>&nbsp;&nbsp;<code>tiles</code>, where each tile has one letter <code>tiles[i]</code> printed on it.</p>
-
-<p>Return <em>the number of possible non-empty sequences of letters</em> you can make using the letters printed on those <code>tiles</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tiles = &quot;AAB&quot;
-<strong>Output:</strong> 8
-<strong>Explanation: </strong>The possible sequences are &quot;A&quot;, &quot;B&quot;, &quot;AA&quot;, &quot;AB&quot;, &quot;BA&quot;, &quot;AAB&quot;, &quot;ABA&quot;, &quot;BAA&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tiles = &quot;AAABBC&quot;
-<strong>Output:</strong> 188
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> tiles = &quot;V&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= tiles.length &lt;= 7</code></li>
-	<li><code>tiles</code> consists of uppercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to build the string with a backtracking DFS by considering what you can put in every position.
-</details>
diff --git a/problems/letter-tile-possibilities/letter_tile_possibilities.go b/problems/letter-tile-possibilities/letter_tile_possibilities.go
deleted file mode 100644
index d7d0d96ab..000000000
--- a/problems/letter-tile-possibilities/letter_tile_possibilities.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem1079
-
-func numTilePossibilities(tiles string) int {
-	count := [26]int{}
-	for _, t := range tiles {
-		count[t-'A']++
-	}
-
-	var dfs func() int
-	dfs = func() int {
-		sum := 0
-		for i := 0; i < 26; i++ {
-			if count[i] == 0 {
-				continue
-			}
-			sum++
-			count[i]--
-			sum += dfs()
-			count[i]++
-		}
-		return sum
-	}
-
-	return dfs()
-}
diff --git a/problems/lexicographical-numbers/README.md b/problems/lexicographical-numbers/README.md
deleted file mode 100644
index 54b4ad933..000000000
--- a/problems/lexicographical-numbers/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../mini-parser "Mini Parser")
-　　　　　　　　　　　　　　　　
-[Next >](../first-unique-character-in-a-string "First Unique Character in a String")
-
-## [386. Lexicographical Numbers (Medium)](https://leetcode.com/problems/lexicographical-numbers "字典序排数")
-
-<p>Given an integer <code>n</code>, return all the numbers in the range <code>[1, n]</code> sorted in lexicographical order.</p>
-
-<p>You must write an algorithm that runs in&nbsp;<code>O(n)</code>&nbsp;time and uses <code>O(1)</code> extra space.&nbsp;</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 13
-<strong>Output:</strong> [1,10,11,12,13,2,3,4,5,6,7,8,9]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 2
-<strong>Output:</strong> [1,2]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Trie](../../tag/trie/README.md)]
diff --git a/problems/lexicographical-numbers/lexicographical_numbers.go b/problems/lexicographical-numbers/lexicographical_numbers.go
deleted file mode 100644
index 9475f6b3e..000000000
--- a/problems/lexicographical-numbers/lexicographical_numbers.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem386
diff --git a/problems/lexicographical-numbers/lexicographical_numbers_test.go b/problems/lexicographical-numbers/lexicographical_numbers_test.go
deleted file mode 100644
index 9475f6b3e..000000000
--- a/problems/lexicographical-numbers/lexicographical_numbers_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem386
diff --git a/problems/lexicographically-smallest-equivalent-string/README.md b/problems/lexicographically-smallest-equivalent-string/README.md
deleted file mode 100644
index a93964e99..000000000
--- a/problems/lexicographically-smallest-equivalent-string/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../missing-element-in-sorted-array "Missing Element in Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-repeating-substring "Longest Repeating Substring")
-
-## [1061. Lexicographically Smallest Equivalent String (Medium)](https://leetcode.com/problems/lexicographically-smallest-equivalent-string "按字典序排列最小的等效字符串")
-
-<p>Given strings <code>A</code> and <code>B</code> of the same length, we say A[i] and B[i] are equivalent characters. For example, if <code>A = &quot;abc&quot;</code> and <code>B = &quot;cde&quot;</code>, then we have <code>&#39;a&#39; == &#39;c&#39;, &#39;b&#39; == &#39;d&#39;, &#39;c&#39; == &#39;e&#39;</code>.</p>
-
-<p>Equivalent characters follow the usual rules of any equivalence relation:</p>
-
-<ul>
-	<li>Reflexivity: &#39;a&#39; == &#39;a&#39;</li>
-	<li>Symmetry: &#39;a&#39; == &#39;b&#39; implies &#39;b&#39; == &#39;a&#39;</li>
-	<li>Transitivity: &#39;a&#39; == &#39;b&#39; and &#39;b&#39; == &#39;c&#39; implies &#39;a&#39; == &#39;c&#39;</li>
-</ul>
-
-<p>For example, given the equivalency information from <code>A</code> and <code>B</code> above, <code>S = &quot;eed&quot;</code>, <code>&quot;acd&quot;</code>, and <code>&quot;aab&quot;</code> are equivalent strings, and <code>&quot;aab&quot;</code> is the lexicographically smallest equivalent string of <code>S</code>.</p>
-
-<p>Return the lexicographically smallest equivalent string of <code>S</code> by using the equivalency information from <code>A</code> and <code>B</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>A = <span id="example-input-1-1">&quot;parker&quot;</span>, B = <span id="example-input-1-2">&quot;morris&quot;</span>, S = <span id="example-input-1-3">&quot;parser&quot;</span>
-<strong>Output: </strong><span id="example-output-1">&quot;makkek&quot;</span>
-<strong>Explanation:</strong> Based on the equivalency information in <code>A</code> and <code>B</code>, we can group their characters as <code>[m,p]</code>, <code>[a,o]</code>, <code>[k,r,s]</code>, <code>[e,i]</code>. The characters in each group are equivalent and sorted in lexicographical order. So the answer is <code>&quot;makkek&quot;</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>A = <span id="example-input-2-1">&quot;hello&quot;</span>, B = <span id="example-input-2-2">&quot;world&quot;</span>, S = <span id="example-input-2-3">&quot;hold&quot;</span>
-<strong>Output: </strong><span id="example-output-2">&quot;hdld&quot;</span>
-<strong>Explanation: </strong> Based on the equivalency information in <code>A</code> and <code>B</code>, we can group their characters as <code>[h,w]</code>, <code>[d,e,o]</code>, <code>[l,r]</code>. So only the second letter <code>&#39;o&#39;</code> in <code>S</code> is changed to <code>&#39;d&#39;</code>, the answer is <code>&quot;hdld&quot;</code>.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong>A = <span id="example-input-3-1">&quot;leetcode&quot;</span>, B = <span id="example-input-3-2">&quot;programs&quot;</span>, S = <span id="example-input-3-3">&quot;sourcecode&quot;</span>
-<strong>Output: </strong><span id="example-output-3">&quot;aauaaaaada&quot;</span>
-<strong>Explanation: </strong> We group the equivalent characters in <code>A</code> and <code>B</code> as <code>[a,o,e,r,s,c]</code>, <code>[l,p]</code>, <code>[g,t]</code> and <code>[d,m]</code>, thus all letters in <code>S</code> except <code>&#39;u&#39;</code> and <code>&#39;d&#39;</code> are transformed to <code>&#39;a&#39;</code>, the answer is <code>&quot;aauaaaaada&quot;</code>.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>String <code>A</code>, <code>B</code> and <code>S</code> consist of only lowercase English letters from <code>&#39;a&#39;</code> - <code>&#39;z&#39;</code>.</li>
-	<li>The lengths of string <code>A</code>, <code>B</code> and <code>S</code> are between <code>1</code> and <code>1000</code>.</li>
-	<li>String <code>A</code> and <code>B</code> are of the same length.</li>
-</ol>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Model these equalities as edges of a graph.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Group each connected component of the graph and assign each node of this component to the node with the lowest lexicographically character.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Finally convert the string with the precalculated information.
-</details>
diff --git a/problems/lexicographically-smallest-string-after-applying-operations/README.md b/problems/lexicographically-smallest-string-after-applying-operations/README.md
deleted file mode 100644
index 09ea81db8..000000000
--- a/problems/lexicographically-smallest-string-after-applying-operations/README.md
+++ /dev/null
@@ -1,96 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-substring-between-two-equal-characters "Largest Substring Between Two Equal Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../best-team-with-no-conflicts "Best Team With No Conflicts")
-
-## [1625. Lexicographically Smallest String After Applying Operations (Medium)](https://leetcode.com/problems/lexicographically-smallest-string-after-applying-operations "执行操作后字典序最小的字符串")
-
-<p>You are given a string <code>s</code> of <strong>even length</strong> consisting of digits from <code>0</code> to <code>9</code>, and two integers <code>a</code> and <code>b</code>.</p>
-
-<p>You can apply either of the following two operations any number of times and in any order on <code>s</code>:</p>
-
-<ul>
-	<li>Add <code>a</code> to all odd indices of <code>s</code> <strong>(0-indexed)</strong>. Digits post <code>9</code> are cycled back to <code>0</code>. For example, if <code>s = &quot;3456&quot;</code> and <code>a = 5</code>, <code>s</code> becomes <code>&quot;3951&quot;</code>.</li>
-	<li>Rotate <code>s</code> to the right by <code>b</code> positions. For example, if <code>s = &quot;3456&quot;</code> and <code>b = 1</code>, <code>s</code> becomes <code>&quot;6345&quot;</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>lexicographically smallest</strong> string you can obtain by applying the above operations any number of times on</em> <code>s</code>.</p>
-
-<p>A string <code>a</code> is lexicographically smaller than a string <code>b</code> (of the same length) if in the first position where <code>a</code> and <code>b</code> differ, string <code>a</code> has a letter that appears earlier in the alphabet than the corresponding letter in <code>b</code>. For example, <code>&quot;0158&quot;</code> is lexicographically smaller than <code>&quot;0190&quot;</code> because the first position they differ is at the third letter, and <code>&#39;5&#39;</code> comes before <code>&#39;9&#39;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;5525&quot;, a = 9, b = 2
-<strong>Output:</strong> &quot;2050&quot;
-<strong>Explanation:</strong> We can apply the following operations:
-Start:  &quot;5525&quot;
-Rotate: &quot;2555&quot;
-Add:    &quot;2454&quot;
-Add:    &quot;2353&quot;
-Rotate: &quot;5323&quot;
-Add:    &quot;5222&quot;
-Add:    &quot;5121&quot;
-Rotate: &quot;2151&quot;
-​​​​​​​Add:    &quot;2050&quot;​​​​​​​​​​​​
-There is no way to obtain a string that is lexicographically smaller then &quot;2050&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;74&quot;, a = 5, b = 1
-<strong>Output:</strong> &quot;24&quot;
-<strong>Explanation:</strong> We can apply the following operations:
-Start:  &quot;74&quot;
-Rotate: &quot;47&quot;
-​​​​​​​Add:    &quot;42&quot;
-​​​​​​​Rotate: &quot;24&quot;​​​​​​​​​​​​
-There is no way to obtain a string that is lexicographically smaller then &quot;24&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0011&quot;, a = 4, b = 2
-<strong>Output:</strong> &quot;0011&quot;
-<strong>Explanation:</strong> There are no sequence of operations that will give us a lexicographically smaller string than &quot;0011&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s.length</code> is even.</li>
-	<li><code>s</code> consists of digits from <code>0</code> to <code>9</code> only.</li>
-	<li><code>1 &lt;= a &lt;= 9</code></li>
-	<li><code>1 &lt;= b &lt;= s.length - 1</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since the length of s is even, the total number of possible sequences is at most 10 * 10 * s.length.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can generate all possible sequences and take their minimum.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Keep track of already generated sequences so they are not processed again.
-</details>
diff --git a/problems/lfu-cache/README.md b/problems/lfu-cache/README.md
deleted file mode 100644
index 2f18a3838..000000000
--- a/problems/lfu-cache/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../repeated-substring-pattern "Repeated Substring Pattern")
-　　　　　　　　　　　　　　　　
-[Next >](../hamming-distance "Hamming Distance")
-
-## [460. LFU Cache (Hard)](https://leetcode.com/problems/lfu-cache "LFU 缓存")
-
-<p>Design and implement a data structure for a <a href="https://en.wikipedia.org/wiki/Least_frequently_used" target="_blank">Least Frequently Used (LFU)</a> cache.</p>
-
-<p>Implement the <code>LFUCache</code> class:</p>
-
-<ul>
-	<li><code>LFUCache(int capacity)</code> Initializes the object with the <code>capacity</code> of the data structure.</li>
-	<li><code>int get(int key)</code> Gets the value of the <code>key</code> if the <code>key</code> exists in the cache. Otherwise, returns <code>-1</code>.</li>
-	<li><code>void put(int key, int value)</code> Update the value of the <code>key</code> if present, or inserts the <code>key</code> if not already present. When the cache reaches its <code>capacity</code>, it should invalidate and remove the <strong>least frequently used</strong> key before inserting a new item. For this problem, when there is a <strong>tie</strong> (i.e., two or more keys with the same frequency), the <strong>least recently used</strong> <code>key</code> would be invalidated.</li>
-</ul>
-
-<p>To determine the least frequently used key, a <strong>use counter</strong> is maintained for each key in the cache. The key with the smallest <strong>use counter</strong> is the least frequently used key.</p>
-
-<p>When a key is first inserted into the cache, its <strong>use counter</strong> is set to <code>1</code> (due to the <code>put</code> operation). The <strong>use counter</strong> for a key in the cache is incremented either a <code>get</code> or <code>put</code> operation is called on it.</p>
-
-<p>The functions&nbsp;<code data-stringify-type="code">get</code>&nbsp;and&nbsp;<code data-stringify-type="code">put</code>&nbsp;must each run in <code>O(1)</code> average time complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;LFUCache&quot;, &quot;put&quot;, &quot;put&quot;, &quot;get&quot;, &quot;put&quot;, &quot;get&quot;, &quot;get&quot;, &quot;put&quot;, &quot;get&quot;, &quot;get&quot;, &quot;get&quot;]
-[[2], [1, 1], [2, 2], [1], [3, 3], [2], [3], [4, 4], [1], [3], [4]]
-<strong>Output</strong>
-[null, null, null, 1, null, -1, 3, null, -1, 3, 4]
-
-<strong>Explanation</strong>
-// cnt(x) = the use counter for key x
-// cache=[] will show the last used order for tiebreakers (leftmost element is  most recent)
-LFUCache lfu = new LFUCache(2);
-lfu.put(1, 1);   // cache=[1,_], cnt(1)=1
-lfu.put(2, 2);   // cache=[2,1], cnt(2)=1, cnt(1)=1
-lfu.get(1);      // return 1
-                 // cache=[1,2], cnt(2)=1, cnt(1)=2
-lfu.put(3, 3);   // 2 is the LFU key because cnt(2)=1 is the smallest, invalidate 2.
-&nbsp;                // cache=[3,1], cnt(3)=1, cnt(1)=2
-lfu.get(2);      // return -1 (not found)
-lfu.get(3);      // return 3
-                 // cache=[3,1], cnt(3)=2, cnt(1)=2
-lfu.put(4, 4);   // Both 1 and 3 have the same cnt, but 1 is LRU, invalidate 1.
-                 // cache=[4,3], cnt(4)=1, cnt(3)=2
-lfu.get(1);      // return -1 (not found)
-lfu.get(3);      // return 3
-                 // cache=[3,4], cnt(4)=1, cnt(3)=3
-lfu.get(4);      // return 4
-                 // cache=[3,4], cnt(4)=2, cnt(3)=3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= capacity&nbsp;&lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= key &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= value &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>2 * 10<sup>5</sup></code>&nbsp;calls will be made to <code>get</code> and <code>put</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<span style="display: none;">&nbsp;</span>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Doubly-Linked List](../../tag/doubly-linked-list/README.md)]
-
-### Similar Questions
-  1. [LRU Cache](../lru-cache) (Medium)
-  1. [Design In-Memory File System](../design-in-memory-file-system) (Hard)
diff --git a/problems/lfu-cache/lfu_cache.go b/problems/lfu-cache/lfu_cache.go
deleted file mode 100644
index fff72b38a..000000000
--- a/problems/lfu-cache/lfu_cache.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem460
diff --git a/problems/lfu-cache/lfu_cache_test.go b/problems/lfu-cache/lfu_cache_test.go
deleted file mode 100644
index fff72b38a..000000000
--- a/problems/lfu-cache/lfu_cache_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem460
diff --git a/problems/license-key-formatting/README.md b/problems/license-key-formatting/README.md
deleted file mode 100644
index 3e4e7ef5e..000000000
--- a/problems/license-key-formatting/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../magical-string "Magical String")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-good-base "Smallest Good Base")
-
-## [482. License Key Formatting (Easy)](https://leetcode.com/problems/license-key-formatting "密钥格式化")
-
-<p>You are given a license key represented as a string <code>s</code> that consists of only alphanumeric characters and dashes. The string is separated into <code>n + 1</code> groups by <code>n</code> dashes. You are also given an integer <code>k</code>.</p>
-
-<p>We want to reformat the string <code>s</code> such that each group contains exactly <code>k</code> characters, except for the first group, which could be shorter than <code>k</code> but still must contain at least one character. Furthermore, there must be a dash inserted between two groups, and you should convert all lowercase letters to uppercase.</p>
-
-<p>Return <em>the reformatted license key</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;5F3Z-2e-9-w&quot;, k = 4
-<strong>Output:</strong> &quot;5F3Z-2E9W&quot;
-<strong>Explanation:</strong> The string s has been split into two parts, each part has 4 characters.
-Note that the two extra dashes are not needed and can be removed.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;2-5g-3-J&quot;, k = 2
-<strong>Output:</strong> &quot;2-5G-3J&quot;
-<strong>Explanation:</strong> The string s has been split into three parts, each part has 2 characters except the first part as it could be shorter as mentioned above.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of English letters, digits, and dashes <code>&#39;-&#39;</code>.</li>
-	<li><code>1 &lt;= k &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/license-key-formatting/license_key_formatting.go b/problems/license-key-formatting/license_key_formatting.go
deleted file mode 100644
index ad2ebae2d..000000000
--- a/problems/license-key-formatting/license_key_formatting.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem482
diff --git a/problems/license-key-formatting/license_key_formatting_test.go b/problems/license-key-formatting/license_key_formatting_test.go
deleted file mode 100644
index ad2ebae2d..000000000
--- a/problems/license-key-formatting/license_key_formatting_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem482
diff --git a/problems/line-reflection/README.md b/problems/line-reflection/README.md
deleted file mode 100644
index ba950f01d..000000000
--- a/problems/line-reflection/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-twitter "Design Twitter")
-　　　　　　　　　　　　　　　　
-[Next >](../count-numbers-with-unique-digits "Count Numbers with Unique Digits")
-
-## [356. Line Reflection (Medium)](https://leetcode.com/problems/line-reflection "直线镜像")
-
-<p>Given n points on a 2D plane, find if there is such a line parallel to y-axis that reflect the given points.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[[1,1],[-1,1]]</span>
-<strong>Output: </strong><span id="example-output-1">true</span>
-</pre>
-
-<div>
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">[[1,1],[-1,-1]]</span>
-<strong>Output: </strong><span id="example-output-2">false</span></pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Max Points on a Line](../max-points-on-a-line) (Hard)
-  1. [Number of Boomerangs](../number-of-boomerangs) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the smallest and largest x-value for all points.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If there is a line then it should be at y = (minX + maxX) / 2.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For each point, make sure that it has a reflected point in the opposite side.
-</details>
diff --git a/problems/line-reflection/line_reflection.go b/problems/line-reflection/line_reflection.go
deleted file mode 100644
index 08682d969..000000000
--- a/problems/line-reflection/line_reflection.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem356
diff --git a/problems/line-reflection/line_reflection_test.go b/problems/line-reflection/line_reflection_test.go
deleted file mode 100644
index 08682d969..000000000
--- a/problems/line-reflection/line_reflection_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem356
diff --git a/problems/linked-list-components/README.md b/problems/linked-list-components/README.md
deleted file mode 100644
index ec94414ff..000000000
--- a/problems/linked-list-components/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ambiguous-coordinates "Ambiguous Coordinates")
-　　　　　　　　　　　　　　　　
-[Next >](../race-car "Race Car")
-
-## [817. Linked List Components (Medium)](https://leetcode.com/problems/linked-list-components "链表组件")
-
-<p>You are given the <code>head</code> of a linked list containing unique integer values and an integer array <code>nums</code> that is a subset of the linked list values.</p>
-
-<p>Return <em>the number of connected components in </em><code>nums</code><em> where two values are connected if they appear <strong>consecutively</strong> in the linked list</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/22/lc-linkedlistcom1.jpg" style="width: 424px; height: 65px;" />
-<pre>
-<strong>Input:</strong> head = [0,1,2,3], nums = [0,1,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 0 and 1 are connected, so [0, 1] and [3] are the two connected components.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/22/lc-linkedlistcom2.jpg" style="width: 544px; height: 65px;" />
-<pre>
-<strong>Input:</strong> head = [0,1,2,3,4], nums = [0,3,1,4]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 0 and 1 are connected, 3 and 4 are connected, so [0, 1] and [3, 4] are the two connected components.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the linked list is <code>n</code>.</li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= Node.val &lt; n</code></li>
-	<li>All the values <code>Node.val</code> are <strong>unique</strong>.</li>
-	<li><code>1 &lt;= nums.length &lt;= n</code></li>
-	<li><code>0 &lt;= nums[i] &lt; n</code></li>
-	<li>All the values of <code>nums</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
diff --git a/problems/linked-list-components/linked_list_components.go b/problems/linked-list-components/linked_list_components.go
deleted file mode 100644
index 2b55ce378..000000000
--- a/problems/linked-list-components/linked_list_components.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem817
diff --git a/problems/linked-list-components/linked_list_components_test.go b/problems/linked-list-components/linked_list_components_test.go
deleted file mode 100644
index 2b55ce378..000000000
--- a/problems/linked-list-components/linked_list_components_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem817
diff --git a/problems/linked-list-cycle-ii/README.md b/problems/linked-list-cycle-ii/README.md
deleted file mode 100644
index df0746b4d..000000000
--- a/problems/linked-list-cycle-ii/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../linked-list-cycle "Linked List Cycle")
-　　　　　　　　　　　　　　　　
-[Next >](../reorder-list "Reorder List")
-
-## [142. Linked List Cycle II (Medium)](https://leetcode.com/problems/linked-list-cycle-ii "环形链表 II")
-
-<p>Given the <code>head</code> of a linked list, return <em>the node where the cycle begins. If there is no cycle, return </em><code>null</code>.</p>
-
-<p>There is a cycle in a linked list if there is some node in the list that can be reached again by continuously following the <code>next</code> pointer. Internally, <code>pos</code> is used to denote the index of the node that tail&#39;s <code>next</code> pointer is connected to (<strong>0-indexed</strong>). It is <code>-1</code> if there is no cycle. <strong>Note that</strong> <code>pos</code> <strong>is not passed as a parameter</strong>.</p>
-
-<p><strong>Do not modify</strong> the linked list.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/07/circularlinkedlist.png" style="height: 145px; width: 450px;" />
-<pre>
-<strong>Input:</strong> head = [3,2,0,-4], pos = 1
-<strong>Output:</strong> tail connects to node index 1
-<strong>Explanation:</strong> There is a cycle in the linked list, where tail connects to the second node.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/07/circularlinkedlist_test2.png" style="height: 105px; width: 201px;" />
-<pre>
-<strong>Input:</strong> head = [1,2], pos = 0
-<strong>Output:</strong> tail connects to node index 0
-<strong>Explanation:</strong> There is a cycle in the linked list, where tail connects to the first node.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/07/circularlinkedlist_test3.png" style="height: 65px; width: 65px;" />
-<pre>
-<strong>Input:</strong> head = [1], pos = -1
-<strong>Output:</strong> no cycle
-<strong>Explanation:</strong> There is no cycle in the linked list.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of the nodes in the list is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-	<li><code>pos</code> is <code>-1</code> or a <strong>valid index</strong> in the linked-list.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Can you solve it using <code>O(1)</code> (i.e. constant) memory?</p>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Linked List Cycle](../linked-list-cycle) (Easy)
-  1. [Find the Duplicate Number](../find-the-duplicate-number) (Medium)
diff --git a/problems/linked-list-cycle-ii/linked_list_cycle_ii.go b/problems/linked-list-cycle-ii/linked_list_cycle_ii.go
deleted file mode 100644
index ee26df3e5..000000000
--- a/problems/linked-list-cycle-ii/linked_list_cycle_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem142
diff --git a/problems/linked-list-cycle-ii/linked_list_cycle_ii_test.go b/problems/linked-list-cycle-ii/linked_list_cycle_ii_test.go
deleted file mode 100644
index ee26df3e5..000000000
--- a/problems/linked-list-cycle-ii/linked_list_cycle_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem142
diff --git a/problems/linked-list-cycle/README.md b/problems/linked-list-cycle/README.md
deleted file mode 100644
index 9a218076f..000000000
--- a/problems/linked-list-cycle/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-break-ii "Word Break II")
-　　　　　　　　　　　　　　　　
-[Next >](../linked-list-cycle-ii "Linked List Cycle II")
-
-## [141. Linked List Cycle (Easy)](https://leetcode.com/problems/linked-list-cycle "环形链表")
-
-<p>Given <code>head</code>, the head of a linked list, determine if the linked list has a cycle in it.</p>
-
-<p>There is a cycle in a linked list if there is some node in the list that can be reached again by continuously following the&nbsp;<code>next</code>&nbsp;pointer. Internally, <code>pos</code>&nbsp;is used to denote the index of the node that&nbsp;tail&#39;s&nbsp;<code>next</code>&nbsp;pointer is connected to.&nbsp;<strong>Note that&nbsp;<code>pos</code>&nbsp;is not passed as a parameter</strong>.</p>
-
-<p>Return&nbsp;<code>true</code><em> if there is a cycle in the linked list</em>. Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/07/circularlinkedlist.png" style="width: 300px; height: 97px; margin-top: 8px; margin-bottom: 8px;" />
-<pre>
-<strong>Input:</strong> head = [3,2,0,-4], pos = 1
-<strong>Output:</strong> true
-<strong>Explanation:</strong> There is a cycle in the linked list, where the tail connects to the 1st node (0-indexed).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/07/circularlinkedlist_test2.png" style="width: 141px; height: 74px;" />
-<pre>
-<strong>Input:</strong> head = [1,2], pos = 0
-<strong>Output:</strong> true
-<strong>Explanation:</strong> There is a cycle in the linked list, where the tail connects to the 0th node.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/07/circularlinkedlist_test3.png" style="width: 45px; height: 45px;" />
-<pre>
-<strong>Input:</strong> head = [1], pos = -1
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There is no cycle in the linked list.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of the nodes in the list is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-	<li><code>pos</code> is <code>-1</code> or a <strong>valid index</strong> in the linked-list.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Can you solve it using <code>O(1)</code> (i.e. constant) memory?</p>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Linked List Cycle II](../linked-list-cycle-ii) (Medium)
-  1. [Happy Number](../happy-number) (Easy)
diff --git a/problems/linked-list-cycle/linked_list_cycle.go b/problems/linked-list-cycle/linked_list_cycle.go
deleted file mode 100644
index cdc748858..000000000
--- a/problems/linked-list-cycle/linked_list_cycle.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package problem141
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func hasCycle(head *ListNode) bool {
-	for p1, p2 := head, head; p1 != nil && p2 != nil; p1 = p1.Next {
-		if p2 = p2.Next; p2 != nil {
-			if p2 = p2.Next; p1 == p2 {
-				return true
-			}
-		}
-	}
-	return false
-}
diff --git a/problems/linked-list-cycle/linked_list_cycle_test.go b/problems/linked-list-cycle/linked_list_cycle_test.go
deleted file mode 100644
index 7581d1cd5..000000000
--- a/problems/linked-list-cycle/linked_list_cycle_test.go
+++ /dev/null
@@ -1,55 +0,0 @@
-package problem141
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	pos  int
-	want bool
-}
-
-func TestHasCycle(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 2, 0, -4},
-			pos:  1,
-			want: true,
-		},
-		{
-			in:   []int{1, 2},
-			pos:  0,
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 3, 4, 5},
-			pos:  -1,
-			want: false,
-		},
-		{
-			in:   []int{1},
-			pos:  -1,
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		in := kit.SliceInt2ListNode(tt.in)
-		p, curr := in, in
-		for i := 0; curr != nil && tt.pos >= 0; i, curr = i+1, curr.Next {
-			if i == tt.pos {
-				p = curr
-			}
-			if curr.Next == nil {
-				curr.Next = p
-				break
-			}
-		}
-		got := hasCycle(in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/linked-list-in-binary-tree/README.md b/problems/linked-list-in-binary-tree/README.md
deleted file mode 100644
index 9b1a71dfe..000000000
--- a/problems/linked-list-in-binary-tree/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rank-teams-by-votes "Rank Teams by Votes")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-make-at-least-one-valid-path-in-a-grid "Minimum Cost to Make at Least One Valid Path in a Grid")
-
-## [1367. Linked List in Binary Tree (Medium)](https://leetcode.com/problems/linked-list-in-binary-tree "二叉树中的列表")
-
-<p>Given a binary tree <code>root</code> and a&nbsp;linked list with&nbsp;<code>head</code>&nbsp;as the first node.&nbsp;</p>
-
-<p>Return True if all the elements in the linked list starting from the <code>head</code> correspond to some <em>downward path</em> connected in the binary tree&nbsp;otherwise return False.</p>
-
-<p>In this context downward path means a path that starts at some node and goes downwards.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/02/12/sample_1_1720.png" style="width: 220px; height: 280px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> head = [4,2,8], root = [1,4,4,null,2,2,null,1,null,6,8,null,null,null,null,1,3]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Nodes in blue form a subpath in the binary Tree.  
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/02/12/sample_2_1720.png" style="width: 220px; height: 280px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1,4,2,6], root = [1,4,4,null,2,2,null,1,null,6,8,null,null,null,null,1,3]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1,4,2,6,8], root = [1,4,4,null,2,2,null,1,null,6,8,null,null,null,null,1,3]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There is no path in the binary tree that contains all the elements of the linked list from <code>head</code>.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree will be in the range <code>[1, 2500]</code>.</li>
-	<li>The number of nodes in the list will be in the range <code>[1, 100]</code>.</li>
-	<li><code>1 &lt;= Node.val&nbsp;&lt;= 100</code>&nbsp;for each node in the linked list and binary tree.</li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create recursive function, given a pointer in a Linked List and any node in the Binary Tree. Check if all the elements in the linked list starting from the head correspond to some downward path in the binary tree.
-</details>
diff --git a/problems/linked-list-random-node/README.md b/problems/linked-list-random-node/README.md
deleted file mode 100644
index d977549d8..000000000
--- a/problems/linked-list-random-node/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../insert-delete-getrandom-o1-duplicates-allowed "Insert Delete GetRandom O(1) - Duplicates allowed")
-　　　　　　　　　　　　　　　　
-[Next >](../ransom-note "Ransom Note")
-
-## [382. Linked List Random Node (Medium)](https://leetcode.com/problems/linked-list-random-node "链表随机节点")
-
-<p>Given a singly linked list, return a random node&#39;s value from the linked list. Each node must have the <strong>same probability</strong> of being chosen.</p>
-
-<p>Implement the <code>Solution</code> class:</p>
-
-<ul>
-	<li><code>Solution(ListNode head)</code> Initializes the object with the integer array nums.</li>
-	<li><code>int getRandom()</code> Chooses a node randomly from the list and returns its value. All the nodes of the list should be equally likely to be choosen.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/16/getrand-linked-list.jpg" style="width: 302px; height: 62px;" />
-<pre>
-<strong>Input</strong>
-[&quot;Solution&quot;, &quot;getRandom&quot;, &quot;getRandom&quot;, &quot;getRandom&quot;, &quot;getRandom&quot;, &quot;getRandom&quot;]
-[[[1, 2, 3]], [], [], [], [], []]
-<strong>Output</strong>
-[null, 1, 3, 2, 2, 3]
-
-<strong>Explanation</strong>
-Solution solution = new Solution([1, 2, 3]);
-solution.getRandom(); // return 1
-solution.getRandom(); // return 3
-solution.getRandom(); // return 2
-solution.getRandom(); // return 2
-solution.getRandom(); // return 3
-// getRandom() should return either 1, 2, or 3 randomly. Each element should have equal probability of returning.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the linked list will be in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>4</sup> &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>getRandom</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>What if the linked list is extremely large and its length is unknown to you?</li>
-	<li>Could you solve this efficiently without using extra space?</li>
-</ul>
-
-### Related Topics
-  [[Reservoir Sampling](../../tag/reservoir-sampling/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Similar Questions
-  1. [Random Pick Index](../random-pick-index) (Medium)
diff --git a/problems/linked-list-random-node/linked_list_random_node.go b/problems/linked-list-random-node/linked_list_random_node.go
deleted file mode 100644
index ad717ba7a..000000000
--- a/problems/linked-list-random-node/linked_list_random_node.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem382
diff --git a/problems/linked-list-random-node/linked_list_random_node_test.go b/problems/linked-list-random-node/linked_list_random_node_test.go
deleted file mode 100644
index ad717ba7a..000000000
--- a/problems/linked-list-random-node/linked_list_random_node_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem382
diff --git a/problems/list-the-products-ordered-in-a-period/README.md b/problems/list-the-products-ordered-in-a-period/README.md
deleted file mode 100644
index d05f83a48..000000000
--- a/problems/list-the-products-ordered-in-a-period/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-taps-to-open-to-water-a-garden "Minimum Number of Taps to Open to Water a Garden")
-　　　　　　　　　　　　　　　　
-[Next >](../break-a-palindrome "Break a Palindrome")
-
-## [1327. List the Products Ordered in a Period (Easy)](https://leetcode.com/problems/list-the-products-ordered-in-a-period "列出指定时间段内所有的下单产品")
-
-SQL Schema
-<p>Table: <code>Products</code></p>
-<pre>
-+------------------+---------+
-| Column Name      | Type    |
-+------------------+---------+
-| product_id       | int     |
-| product_name     | varchar |
-| product_category | varchar |
-+------------------+---------+
-product_id is the primary key for this table.
-This table contains data about the company's products.
-</pre>
-
-<p>Table: <code>Orders</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| product_id    | int     |
-| order_date    | date    |
-| unit          | int     |
-+---------------+---------+
-There is no primary key for this table. It may have duplicate rows.
-product_id is a foreign key to Products table.
-unit is the number of products ordered in order_date.
-</pre>
- 
-Write an SQL query to get the names of products with greater than or equal to 100 units ordered in February 2020 and their amount.
-
-Return result table in any order.
-
-The query result format is in the following example:
-<pre>
-Products table:
-+-------------+-----------------------+------------------+
-| product_id  | product_name          | product_category |
-+-------------+-----------------------+------------------+
-| 1           | Leetcode Solutions    | Book             |
-| 2           | Jewels of Stringology | Book             |
-| 3           | HP                    | Laptop           |
-| 4           | Lenovo                | Laptop           |
-| 5           | Leetcode Kit          | T-shirt          |
-+-------------+-----------------------+------------------+
-
-Orders table:
-+--------------+--------------+----------+
-| product_id   | order_date   | unit     |
-+--------------+--------------+----------+
-| 1            | 2020-02-05   | 60       |
-| 1            | 2020-02-10   | 70       |
-| 2            | 2020-01-18   | 30       |
-| 2            | 2020-02-11   | 80       |
-| 3            | 2020-02-17   | 2        |
-| 3            | 2020-02-24   | 3        |
-| 4            | 2020-03-01   | 20       |
-| 4            | 2020-03-04   | 30       |
-| 4            | 2020-03-04   | 60       |
-| 5            | 2020-02-25   | 50       |
-| 5            | 2020-02-27   | 50       |
-| 5            | 2020-03-01   | 50       |
-+--------------+--------------+----------+
-
-Result table:
-+--------------------+---------+
-| product_name       | unit    |
-+--------------------+---------+
-| Leetcode Solutions | 130     |
-| Leetcode Kit       | 100     |
-+--------------------+---------+
-
-Products with product_id = 1 is ordered in February a total of (60 + 70) = 130.
-Products with product_id = 2 is ordered in February a total of 80.
-Products with product_id = 3 is ordered in February a total of (2 + 3) = 5.
-Products with product_id = 4 was not ordered in February 2020.
-Products with product_id = 5 is ordered in February a total of (50 + 50) = 100.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/list-the-products-ordered-in-a-period/mysql_schemas.sql b/problems/list-the-products-ordered-in-a-period/mysql_schemas.sql
deleted file mode 100644
index a69778f8f..000000000
--- a/problems/list-the-products-ordered-in-a-period/mysql_schemas.sql
+++ /dev/null
@@ -1,21 +0,0 @@
-Create table If Not Exists Products (product_id int, product_name varchar(40), product_category varchar(40));
-Create table If Not Exists Orders (product_id int, order_date date, unit int);
-Truncate table Products;
-insert into Products (product_id, product_name, product_category) values ('1', 'Leetcode Solutions', 'Book');
-insert into Products (product_id, product_name, product_category) values ('2', 'Jewels of Stringology', 'Book');
-insert into Products (product_id, product_name, product_category) values ('3', 'HP', 'Laptop');
-insert into Products (product_id, product_name, product_category) values ('4', 'Lenovo', 'Laptop');
-insert into Products (product_id, product_name, product_category) values ('5', 'Leetcode Kit', 'T-shirt');
-Truncate table Orders;
-insert into Orders (product_id, order_date, unit) values ('1', '2020-02-05', '60');
-insert into Orders (product_id, order_date, unit) values ('1', '2020-02-10', '70');
-insert into Orders (product_id, order_date, unit) values ('2', '2020-01-18', '30');
-insert into Orders (product_id, order_date, unit) values ('2', '2020-02-11', '80');
-insert into Orders (product_id, order_date, unit) values ('3', '2020-02-17', '2');
-insert into Orders (product_id, order_date, unit) values ('3', '2020-02-24', '3');
-insert into Orders (product_id, order_date, unit) values ('4', '2020-03-01', '20');
-insert into Orders (product_id, order_date, unit) values ('4', '2020-03-04', '30');
-insert into Orders (product_id, order_date, unit) values ('4', '2020-03-04', '60');
-insert into Orders (product_id, order_date, unit) values ('5', '2020-02-25', '50');
-insert into Orders (product_id, order_date, unit) values ('5', '2020-02-27', '50');
-insert into Orders (product_id, order_date, unit) values ('5', '2020-03-01', '50');
diff --git a/problems/logger-rate-limiter/README.md b/problems/logger-rate-limiter/README.md
deleted file mode 100644
index 52a6f01b0..000000000
--- a/problems/logger-rate-limiter/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rearrange-string-k-distance-apart "Rearrange String k Distance Apart")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-transformed-array "Sort Transformed Array")
-
-## [359. Logger Rate Limiter (Easy)](https://leetcode.com/problems/logger-rate-limiter "日志速率限制器")
-
-<p>Design a logger system that receive stream of messages along with its timestamps, each message should be printed if and only if it is <b>not printed in the last 10 seconds</b>.</p>
-
-<p>Given a message and a timestamp (in seconds granularity), return true if the message should be printed in the given timestamp, otherwise returns false.</p>
-
-<p>It is possible that several messages arrive roughly at the same time.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-Logger logger = new Logger();
-
-// logging string &quot;foo&quot; at timestamp 1
-logger.shouldPrintMessage(1, &quot;foo&quot;); returns true; 
-
-// logging string &quot;bar&quot; at timestamp 2
-logger.shouldPrintMessage(2,&quot;bar&quot;); returns true;
-
-// logging string &quot;foo&quot; at timestamp 3
-logger.shouldPrintMessage(3,&quot;foo&quot;); returns false;
-
-// logging string &quot;bar&quot; at timestamp 8
-logger.shouldPrintMessage(8,&quot;bar&quot;); returns false;
-
-// logging string &quot;foo&quot; at timestamp 10
-logger.shouldPrintMessage(10,&quot;foo&quot;); returns false;
-
-// logging string &quot;foo&quot; at timestamp 11
-logger.shouldPrintMessage(11,&quot;foo&quot;); returns true;
-</pre>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [Design Hit Counter](../design-hit-counter) (Medium)
diff --git a/problems/logger-rate-limiter/logger_rate_limiter.go b/problems/logger-rate-limiter/logger_rate_limiter.go
deleted file mode 100644
index e670b8717..000000000
--- a/problems/logger-rate-limiter/logger_rate_limiter.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem359
diff --git a/problems/logger-rate-limiter/logger_rate_limiter_test.go b/problems/logger-rate-limiter/logger_rate_limiter_test.go
deleted file mode 100644
index e670b8717..000000000
--- a/problems/logger-rate-limiter/logger_rate_limiter_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem359
diff --git a/problems/logical-or-of-two-binary-grids-represented-as-quad-trees/README.md b/problems/logical-or-of-two-binary-grids-represented-as-quad-trees/README.md
deleted file mode 100644
index 2cae6fc92..000000000
--- a/problems/logical-or-of-two-binary-grids-represented-as-quad-trees/README.md
+++ /dev/null
@@ -1,114 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-words-in-a-string-iii "Reverse Words in a String III")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-depth-of-n-ary-tree "Maximum Depth of N-ary Tree")
-
-## [558. Logical OR of Two Binary Grids Represented as Quad-Trees (Medium)](https://leetcode.com/problems/logical-or-of-two-binary-grids-represented-as-quad-trees "四叉树交集")
-
-<p>A Binary Matrix is a matrix in which all the elements are either <strong>0</strong> or <strong>1</strong>.</p>
-
-<p>Given <code>quadTree1</code> and <code>quadTree2</code>. <code>quadTree1</code> represents a <code>n * n</code> binary matrix and <code>quadTree2</code> represents another&nbsp;<code>n * n</code> binary matrix.&nbsp;</p>
-
-<p>Return <em>a Quad-Tree</em> representing the <code>n * n</code> binary matrix which is the result of <strong>logical bitwise OR</strong> of the two binary matrixes represented by <code>quadTree1</code> and <code>quadTree2</code>.</p>
-
-<p>Notice that you can assign the value of a node to <strong>True</strong> or <strong>False</strong> when <code>isLeaf</code> is <strong>False</strong>, and both are <strong>accepted</strong> in the answer.</p>
-
-<p>A Quad-Tree is a tree data structure in which each internal node has exactly four children. Besides, each node has two attributes:</p>
-
-<ul>
-	<li><code>val</code>: True if the node represents a grid of 1&#39;s or False if the node represents a grid of 0&#39;s.&nbsp;</li>
-	<li><code>isLeaf</code>: True if the node is leaf node on the tree or False if the node has the four children.</li>
-</ul>
-
-<pre>
-class Node {
-    public boolean val;
-&nbsp; &nbsp; public boolean isLeaf;
-&nbsp; &nbsp; public Node topLeft;
-&nbsp; &nbsp; public Node topRight;
-&nbsp; &nbsp; public Node bottomLeft;
-&nbsp; &nbsp; public Node bottomRight;
-}</pre>
-
-<p>We can construct a Quad-Tree from a two-dimensional area using the following steps:</p>
-
-<ol>
-	<li>If the current grid has the same value (i.e all <code>1&#39;s</code> or all <code>0&#39;s</code>)&nbsp;set <code>isLeaf</code>&nbsp;True and set <code>val</code> to the value of the grid and set the four children to Null and stop.</li>
-	<li>If the current grid has different values, set <code>isLeaf</code> to False and&nbsp;set <code>val</code> to any value and divide the current grid into four sub-grids as shown in the photo.</li>
-	<li>Recurse for each of the children with the proper sub-grid.</li>
-</ol>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/11/new_top.png" style="width: 777px; height: 181px;" />
-<p>If you want to know more about the Quad-Tree, you can refer to the&nbsp;<a href="https://en.wikipedia.org/wiki/Quadtree">wiki</a>.</p>
-
-<p><strong>Quad-Tree&nbsp;format:</strong></p>
-
-<p>The input/output represents the serialized format of a Quad-Tree using level order traversal, where <code>null</code> signifies a path terminator where no node exists below.</p>
-
-<p>It is very similar to the serialization of the binary tree. The only difference is that the node is represented as a list <code>[isLeaf, val]</code>.</p>
-
-<p>If the value of <code>isLeaf</code> or <code>val</code> is True we represent it as <strong>1</strong> in the list&nbsp;<code>[isLeaf, val]</code> and if the value of <code>isLeaf</code> or <code>val</code> is False we represent it as <strong>0</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/11/qt1.png" style="width: 550px; height: 196px;" /> <img alt="" src="https://assets.leetcode.com/uploads/2020/02/11/qt2.png" style="width: 550px; height: 278px;" />
-<pre>
-<strong>Input:</strong> quadTree1 = [[0,1],[1,1],[1,1],[1,0],[1,0]]
-, quadTree2 = [[0,1],[1,1],[0,1],[1,1],[1,0],null,null,null,null,[1,0],[1,0],[1,1],[1,1]]
-<strong>Output:</strong> [[0,0],[1,1],[1,1],[1,1],[1,0]]
-<strong>Explanation:</strong> quadTree1 and quadTree2 are shown above. You can see the binary matrix which is represented by each Quad-Tree.
-If we apply logical bitwise OR on the two binary matrices we get the binary matrix below which is represented by the result Quad-Tree.
-Notice that the binary matrices shown are only for illustration, you don&#39;t have to construct the binary matrix to get the result tree.
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/11/qtr.png" style="width: 777px; height: 222px;" />
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> quadTree1 = [[1,0]]
-, quadTree2 = [[1,0]]
-<strong>Output:</strong> [[1,0]]
-<strong>Explanation:</strong> Each tree represents a binary matrix of size 1*1. Each matrix contains only zero.
-The resulting matrix is of size 1*1 with also zero.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> quadTree1 = [[0,0],[1,0],[1,0],[1,1],[1,1]]
-, quadTree2 = [[0,0],[1,1],[1,1],[1,0],[1,1]]
-<strong>Output:</strong> [[1,1]]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> quadTree1 = [[0,0],[1,1],[1,0],[1,1],[1,1]]
-, quadTree2 = [[0,0],[1,1],[0,1],[1,1],[1,1],null,null,null,null,[1,1],[1,0],[1,0],[1,1]]
-<strong>Output:</strong> [[0,0],[1,1],[0,1],[1,1],[1,1],null,null,null,null,[1,1],[1,0],[1,0],[1,1]]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> quadTree1 = [[0,1],[1,0],[0,1],[1,1],[1,0],null,null,null,null,[1,0],[1,0],[1,1],[1,1]]
-, quadTree2 = [[0,1],[0,1],[1,0],[1,1],[1,0],[1,0],[1,0],[1,1],[1,1]]
-<strong>Output:</strong> [[0,0],[0,1],[0,1],[1,1],[1,0],[1,0],[1,0],[1,1],[1,1],[1,0],[1,0],[1,1],[1,1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>quadTree1</code> and <code>quadTree2</code> are both <strong>valid</strong> Quad-Trees each representing a <code>n * n</code> grid.</li>
-	<li><code>n == 2^x</code> where <code>0 &lt;= x &lt;= 9</code>.</li>
-</ul>
-
-### Related Topics
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Tree](../../tag/tree/README.md)]
diff --git a/problems/lonely-pixel-i/README.md b/problems/lonely-pixel-i/README.md
deleted file mode 100644
index 5a6dda563..000000000
--- a/problems/lonely-pixel-i/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-absolute-difference-in-bst "Minimum Absolute Difference in BST")
-　　　　　　　　　　　　　　　　
-[Next >](../k-diff-pairs-in-an-array "K-diff Pairs in an Array")
-
-## [531. Lonely Pixel I (Medium)](https://leetcode.com/problems/lonely-pixel-i "孤独像素 I")
-
-<p>Given a picture consisting of black and white pixels, find the number of <b>black</b> lonely pixels.</p>
-
-<p>The picture is represented by a 2D char array consisting of 'B' and 'W', which means black and white pixels respectively. </p>
-
-<p>A black lonely pixel is character 'B' that located at a specific position where the same row and same column don't have any other black pixels.</p>
-
-<p><b>Example:</b><br />
-<pre>
-<b>Input:</b> 
-[['W', 'W', 'B'],
- ['W', 'B', 'W'],
- ['B', 'W', 'W']]
-
-<b>Output:</b> 3
-<b>Explanation:</b> All the three 'B's are black lonely pixels.
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>The range of width and height of the input 2D array is [1,500].</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Lonely Pixel II](../lonely-pixel-ii) (Medium)
diff --git a/problems/lonely-pixel-i/lonely_pixel_i.go b/problems/lonely-pixel-i/lonely_pixel_i.go
deleted file mode 100644
index 23477ac60..000000000
--- a/problems/lonely-pixel-i/lonely_pixel_i.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem531
diff --git a/problems/lonely-pixel-i/lonely_pixel_i_test.go b/problems/lonely-pixel-i/lonely_pixel_i_test.go
deleted file mode 100644
index 23477ac60..000000000
--- a/problems/lonely-pixel-i/lonely_pixel_i_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem531
diff --git a/problems/lonely-pixel-ii/README.md b/problems/lonely-pixel-ii/README.md
deleted file mode 100644
index 09c10977b..000000000
--- a/problems/lonely-pixel-ii/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-diff-pairs-in-an-array "K-diff Pairs in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../game-play-analysis-iii "Game Play Analysis III")
-
-## [533. Lonely Pixel II (Medium)](https://leetcode.com/problems/lonely-pixel-ii "孤独像素 II")
-
-<p>Given a picture consisting of black and white pixels, and a positive integer N, find the number of black pixels located at some specific row <b>R</b> and column <b>C</b> that align with all the following rules:</p>
-
-<ol>
-<li> Row R and column C both contain exactly N black pixels.</li>
-<li> For all rows that have a black pixel at column C, they should be exactly the same as row R</li>
-</ol>
-
-<p>The picture is represented by a 2D char array consisting of 'B' and 'W', which means black and white pixels respectively. </p>
-
-<p><b>Example:</b><br />
-<pre>
-<b>Input:</b>                                            
-[['W', 'B', 'W', 'B', 'B', 'W'],    
- ['W', 'B', 'W', 'B', 'B', 'W'],    
- ['W', 'B', 'W', 'B', 'B', 'W'],    
- ['W', 'W', 'B', 'W', 'B', 'W']] 
-
-N = 3
-<b>Output:</b> 6
-<b>Explanation:</b> All the bold 'B' are the black pixels we need (all 'B's at column 1 and 3).
-        0    1    2    3    4    5         column index                                            
-0    [['W', <b>'B'</b>, 'W', <b>'B'</b>, 'B', 'W'],    
-1     ['W', <b>'B'</b>, 'W', <b>'B'</b>, 'B', 'W'],    
-2     ['W', <b>'B'</b>, 'W', <b>'B'</b>, 'B', 'W'],    
-3     ['W', 'W', 'B', 'W', 'B', 'W']]    
-row index
-
-Take 'B' at row R = 0 and column C = 1 as an example:
-Rule 1, row R = 0 and column C = 1 both have exactly N = 3 black pixels. 
-Rule 2, the rows have black pixel at column C = 1 are row 0, row 1 and row 2. They are exactly the same as row R = 0.
-
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>The range of width and height of the input 2D array is [1,200].</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Lonely Pixel I](../lonely-pixel-i) (Medium)
diff --git a/problems/lonely-pixel-ii/lonely_pixel_ii.go b/problems/lonely-pixel-ii/lonely_pixel_ii.go
deleted file mode 100644
index 62681c696..000000000
--- a/problems/lonely-pixel-ii/lonely_pixel_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem533
diff --git a/problems/lonely-pixel-ii/lonely_pixel_ii_test.go b/problems/lonely-pixel-ii/lonely_pixel_ii_test.go
deleted file mode 100644
index 62681c696..000000000
--- a/problems/lonely-pixel-ii/lonely_pixel_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem533
diff --git a/problems/long-pressed-name/README.md b/problems/long-pressed-name/README.md
deleted file mode 100644
index 490632cb6..000000000
--- a/problems/long-pressed-name/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimize-malware-spread "Minimize Malware Spread")
-　　　　　　　　　　　　　　　　
-[Next >](../flip-string-to-monotone-increasing "Flip String to Monotone Increasing")
-
-## [925. Long Pressed Name (Easy)](https://leetcode.com/problems/long-pressed-name "长按键入")
-
-<p>Your friend is typing his <code>name</code> into a keyboard. Sometimes, when typing a character <code>c</code>, the key might get <em>long pressed</em>, and the character will be typed 1 or more times.</p>
-
-<p>You examine the <code>typed</code> characters of the keyboard. Return <code>True</code> if it is possible that it was your friends name, with some characters (possibly none) being long pressed.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> name = &quot;alex&quot;, typed = &quot;aaleex&quot;
-<strong>Output:</strong> true
-<strong>Explanation: </strong>&#39;a&#39; and &#39;e&#39; in &#39;alex&#39; were long pressed.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> name = &quot;saeed&quot;, typed = &quot;ssaaedd&quot;
-<strong>Output:</strong> false
-<strong>Explanation: </strong>&#39;e&#39; must have been pressed twice, but it wasn&#39;t in the typed output.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> name = &quot;leelee&quot;, typed = &quot;lleeelee&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> name = &quot;laiden&quot;, typed = &quot;laiden&quot;
-<strong>Output:</strong> true
-<strong>Explanation: </strong>It&#39;s not necessary to long press any character.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= name.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= typed.length &lt;= 1000</code></li>
-	<li><code>name</code> and <code>typed</code> contain only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/long-pressed-name/long_pressed_name.go b/problems/long-pressed-name/long_pressed_name.go
deleted file mode 100644
index 918f28da7..000000000
--- a/problems/long-pressed-name/long_pressed_name.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem925
-
-func isLongPressedName(name string, typed string) bool {
-	i, nl, j, tl := 0, len(name), 0, len(typed)
-	for i < nl || j < tl {
-		if i < nl && j < tl && name[i] == typed[j] {
-			i++
-			j++
-		} else if i >= 1 && j < tl && typed[j] == name[i-1] {
-			j++
-		} else {
-			return false
-		}
-	}
-	return true
-}
diff --git a/problems/long-pressed-name/long_pressed_name_test.go b/problems/long-pressed-name/long_pressed_name_test.go
deleted file mode 100644
index 25697c9c1..000000000
--- a/problems/long-pressed-name/long_pressed_name_test.go
+++ /dev/null
@@ -1,65 +0,0 @@
-package problem925
-
-import "testing"
-
-type testType struct {
-	name  string
-	typed string
-	want  bool
-}
-
-func TestIsLongPressedName(t *testing.T) {
-	tests := [...]testType{
-		{
-			name:  "alex",
-			typed: "aaleex",
-			want:  true,
-		},
-		{
-			name:  "saeed",
-			typed: "ssaaedd",
-			want:  false,
-		},
-		{
-			name:  "leelee",
-			typed: "lleeelee",
-			want:  true,
-		},
-		{
-			name:  "laiden",
-			typed: "laiden",
-			want:  true,
-		},
-		{
-			name:  "laiden",
-			typed: "laidef",
-			want:  false,
-		},
-		{
-			name:  "a",
-			typed: "a",
-			want:  true,
-		},
-		{
-			name:  "a",
-			typed: "b",
-			want:  false,
-		},
-		{
-			name:  "pyplrz",
-			typed: "ppyypllr",
-			want:  false,
-		},
-		{
-			name:  "vtkgn",
-			typed: "vttkgnn",
-			want:  true,
-		},
-	}
-	for _, tt := range tests {
-		got := isLongPressedName(tt.name, tt.typed)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.name, tt.typed, got, tt.want)
-		}
-	}
-}
diff --git a/problems/longer-contiguous-segments-of-ones-than-zeros/README.md b/problems/longer-contiguous-segments-of-ones-than-zeros/README.md
deleted file mode 100644
index a95dfe168..000000000
--- a/problems/longer-contiguous-segments-of-ones-than-zeros/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../product-of-two-run-length-encoded-arrays "Product of Two Run-Length Encoded Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-speed-to-arrive-on-time "Minimum Speed to Arrive on Time")
-
-## [1869. Longer Contiguous Segments of Ones than Zeros (Easy)](https://leetcode.com/problems/longer-contiguous-segments-of-ones-than-zeros "哪种连续子字符串更长")
-
-<p>Given a binary string <code>s</code>, return <code>true</code><em> if the <strong>longest</strong> contiguous segment of </em><code>1</code>&#39;<em>s is <strong>strictly longer</strong> than the <strong>longest</strong> contiguous segment of </em><code>0</code>&#39;<em>s in </em><code>s</code>, or return <code>false</code><em> otherwise</em>.</p>
-
-<ul>
-	<li>For example, in <code>s = &quot;<u>11</u>01<u>000</u>10&quot;</code> the longest continuous segment of <code>1</code>s has length <code>2</code>, and the longest continuous segment of <code>0</code>s has length <code>3</code>.</li>
-</ul>
-
-<p>Note that if there are no <code>0</code>&#39;s, then the longest continuous segment of <code>0</code>&#39;s is considered to have a length <code>0</code>. The same applies if there is no <code>1</code>&#39;s.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1101&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-The longest contiguous segment of 1s has length 2: &quot;<u>11</u>01&quot;
-The longest contiguous segment of 0s has length 1: &quot;11<u>0</u>1&quot;
-The segment of 1s is longer, so return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;111000&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-The longest contiguous segment of 1s has length 3: &quot;<u>111</u>000&quot;
-The longest contiguous segment of 0s has length 3: &quot;111<u>000</u>&quot;
-The segment of 1s is not longer, so return false.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;110100010&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-The longest contiguous segment of 1s has length 2: &quot;<u>11</u>0100010&quot;
-The longest contiguous segment of 0s has length 3: &quot;1101<u>000</u>10&quot;
-The segment of 1s is not longer, so return false.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Max Consecutive Ones](../max-consecutive-ones) (Easy)
-  1. [Count Subarrays With More Ones Than Zeros](../count-subarrays-with-more-ones-than-zeros) (Medium)
-  1. [Check if Binary String Has at Most One Segment of Ones](../check-if-binary-string-has-at-most-one-segment-of-ones) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check every possible segment of 0s and 1s.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is there a way to iterate through the string to keep track of the current character and its count?
-</details>
diff --git a/problems/longest-absolute-file-path/README.md b/problems/longest-absolute-file-path/README.md
deleted file mode 100644
index 12ed18bb9..000000000
--- a/problems/longest-absolute-file-path/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../first-unique-character-in-a-string "First Unique Character in a String")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-difference "Find the Difference")
-
-## [388. Longest Absolute File Path (Medium)](https://leetcode.com/problems/longest-absolute-file-path "文件的最长绝对路径")
-
-<p>Suppose we have a file system that stores both files and directories. An example of one system is represented in the following picture:</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/08/28/mdir.jpg" style="width: 681px; height: 322px;" /></p>
-
-<p>Here, we have <code>dir</code> as the only directory in the root. <code>dir</code> contains two subdirectories, <code>subdir1</code> and <code>subdir2</code>. <code>subdir1</code> contains a file <code>file1.ext</code> and subdirectory <code>subsubdir1</code>. <code>subdir2</code> contains a subdirectory <code>subsubdir2</code>, which contains a file <code>file2.ext</code>.</p>
-
-<p>In text form, it looks like this (with ⟶ representing the tab character):</p>
-
-<pre>
-dir
-⟶ subdir1
-⟶ ⟶ file1.ext
-⟶ ⟶ subsubdir1
-⟶ subdir2
-⟶ ⟶ subsubdir2
-⟶ ⟶ ⟶ file2.ext
-</pre>
-
-<p>If we were to write this representation in code, it will look like this: <code>&quot;dir\n\tsubdir1\n\t\tfile1.ext\n\t\tsubsubdir1\n\tsubdir2\n\t\tsubsubdir2\n\t\t\tfile2.ext&quot;</code>. Note that the <code>&#39;\n&#39;</code> and <code>&#39;\t&#39;</code> are the new-line and tab characters.</p>
-
-<p>Every file and directory has a unique <strong>absolute path</strong> in the file system, which is the order of directories that must be opened to reach the file/directory itself, all concatenated by <code>&#39;/&#39;s</code>. Using the above example, the <strong>absolute path</strong> to <code>file2.ext</code> is <code>&quot;dir/subdir2/subsubdir2/file2.ext&quot;</code>. Each directory name consists of letters, digits, and/or spaces. Each file name is of the form <code>name.extension</code>, where <code>name</code> and <code>extension</code> consist of letters, digits, and/or spaces.</p>
-
-<p>Given a string <code>input</code> representing the file system in the explained format, return <em>the length of the <strong>longest absolute path</strong> to a <strong>file</strong> in the abstracted file system</em>. If there is no file in the system, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/28/dir1.jpg" style="width: 401px; height: 202px;" />
-<pre>
-<strong>Input:</strong> input = &quot;dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext&quot;
-<strong>Output:</strong> 20
-<strong>Explanation:</strong> We have only one file, and the absolute path is &quot;dir/subdir2/file.ext&quot; of length 20.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/28/dir2.jpg" style="width: 641px; height: 322px;" />
-<pre>
-<strong>Input:</strong> input = &quot;dir\n\tsubdir1\n\t\tfile1.ext\n\t\tsubsubdir1\n\tsubdir2\n\t\tsubsubdir2\n\t\t\tfile2.ext&quot;
-<strong>Output:</strong> 32
-<strong>Explanation:</strong> We have two files:
-&quot;dir/subdir1/file1.ext&quot; of length 21
-&quot;dir/subdir2/subsubdir2/file2.ext&quot; of length 32.
-We return 32 since it is the longest absolute path to a file.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> input = &quot;a&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> We do not have any files, just a single directory named &quot;a&quot;.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> input = &quot;file1.txt\nfile2.txt\nlongfile.txt&quot;
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> There are 3 files at the root directory.
-Since the absolute path for anything at the root directory is just the name itself, the answer is &quot;longfile.txt&quot; with length 12.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= input.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>input</code> may contain lowercase or uppercase English letters, a new line character <code>&#39;\n&#39;</code>, a tab character <code>&#39;\t&#39;</code>, a dot <code>&#39;.&#39;</code>, a space <code>&#39; &#39;</code>, and digits.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/longest-absolute-file-path/longest_absolute_file_path.go b/problems/longest-absolute-file-path/longest_absolute_file_path.go
deleted file mode 100644
index 4acc336b2..000000000
--- a/problems/longest-absolute-file-path/longest_absolute_file_path.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem388
diff --git a/problems/longest-absolute-file-path/longest_absolute_file_path_test.go b/problems/longest-absolute-file-path/longest_absolute_file_path_test.go
deleted file mode 100644
index 4acc336b2..000000000
--- a/problems/longest-absolute-file-path/longest_absolute_file_path_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem388
diff --git a/problems/longest-arithmetic-sequence/README.md b/problems/longest-arithmetic-sequence/README.md
deleted file mode 100644
index 8703dfe66..000000000
--- a/problems/longest-arithmetic-sequence/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-difference-between-node-and-ancestor "Maximum Difference Between Node and Ancestor")
-　　　　　　　　　　　　　　　　
-[Next >](../recover-a-tree-from-preorder-traversal "Recover a Tree From Preorder Traversal")
-
-## [1027. Longest Arithmetic Sequence (Medium)](https://leetcode.com/problems/longest-arithmetic-sequence "最长等差数列")
-
-<p>Given an array <code>A</code> of integers, return the <strong>length</strong> of the longest arithmetic subsequence in <code>A</code>.</p>
-
-<p>Recall that a <em>subsequence</em> of <code>A</code> is a list <code>A[i_1], A[i_2], ..., A[i_k]</code> with <code>0 &lt;= i_1 &lt; i_2 &lt; ... &lt; i_k &lt;= A.length - 1</code>, and that a sequence <code>B</code>&nbsp;is <em>arithmetic</em> if <code>B[i+1] - B[i]</code> are all the same value (for <code>0 &lt;= i &lt; B.length - 1</code>).</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[3,6,9,12]</span>
-<strong>Output: </strong><span id="example-output-1">4</span>
-<strong>Explanation: </strong>
-The whole array is an arithmetic sequence with steps of length = 3.
-</pre>
-
-<div>
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">[9,4,7,2,10]</span>
-<strong>Output: </strong><span id="example-output-2">3</span>
-<strong>Explanation: </strong>
-The longest arithmetic subsequence is [4,7,10].
-</pre>
-
-<div>
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-3-1">[20,1,15,3,10,5,8]</span>
-<strong>Output: </strong><span id="example-output-3">4</span>
-<strong>Explanation: </strong>
-The longest arithmetic subsequence is [20,15,10,5].
-</pre>
-</div>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>2 &lt;= A.length &lt;= 2000</code></li>
-	<li><code>0 &lt;= A[i] &lt;= 10000</code></li>
-</ol>
-</div>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/longest-arithmetic-sequence/longest_arithmetic_sequence.go b/problems/longest-arithmetic-sequence/longest_arithmetic_sequence.go
deleted file mode 100644
index 36fde551a..000000000
--- a/problems/longest-arithmetic-sequence/longest_arithmetic_sequence.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package problem1027
-
-func longestArithSeqLength(A []int) int {
-	n := len(A)
-
-	indexes := [10001][]int{}
-	for i := 0; i < n; i++ {
-		indexes[A[i]] = append(indexes[A[i]], i)
-	}
-
-	var dfs func(int, int) int
-	dfs = func(j, diff int) int {
-		next := A[j] + diff
-		if next < 0 || 10000 < next {
-			return 0
-		}
-		for _, k := range indexes[next] {
-			if j < k {
-				return 1 + dfs(k, diff)
-			}
-		}
-		return 0
-	}
-
-	res := 0
-	for i := 0; i < n; i++ {
-		for j := i + 1; j < n; j++ {
-			diff := A[j] - A[i]
-			res = max(res, 2+dfs(j, diff))
-		}
-	}
-
-	return res
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/longest-arithmetic-subsequence-of-given-difference/README.md b/problems/longest-arithmetic-subsequence-of-given-difference/README.md
deleted file mode 100644
index dc350155e..000000000
--- a/problems/longest-arithmetic-subsequence-of-given-difference/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-move-chips-to-the-same-position "Minimum Cost to Move Chips to The Same Position")
-　　　　　　　　　　　　　　　　
-[Next >](../path-with-maximum-gold "Path with Maximum Gold")
-
-## [1218. Longest Arithmetic Subsequence of Given Difference (Medium)](https://leetcode.com/problems/longest-arithmetic-subsequence-of-given-difference "最长定差子序列")
-
-<p>Given an integer array <code>arr</code> and an integer <code>difference</code>, return the length of the longest subsequence in <code>arr</code> which is an arithmetic sequence such that the difference between adjacent elements in the subsequence equals <code>difference</code>.</p>
-
-<p>A <strong>subsequence</strong> is a sequence that can be derived from <code>arr</code> by deleting some or no elements without changing the order of the remaining elements.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4], difference = 1
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>The longest arithmetic subsequence is [1,2,3,4].</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,3,5,7], difference = 1
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>The longest arithmetic subsequence is any single element.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,5,7,8,5,3,4,2,1], difference = -2
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>The longest arithmetic subsequence is [7,5,3,1].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= arr[i], difference &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let dp[i] be the maximum length of a subsequence of the given difference whose last element is i.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-dp[i] = 1 + dp[i-k]
-</details>
diff --git a/problems/longest-arithmetic-subsequence/README.md b/problems/longest-arithmetic-subsequence/README.md
deleted file mode 100644
index 33b7de800..000000000
--- a/problems/longest-arithmetic-subsequence/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-difference-between-node-and-ancestor "Maximum Difference Between Node and Ancestor")
-　　　　　　　　　　　　　　　　
-[Next >](../recover-a-tree-from-preorder-traversal "Recover a Tree From Preorder Traversal")
-
-## [1027. Longest Arithmetic Subsequence (Medium)](https://leetcode.com/problems/longest-arithmetic-subsequence "最长等差数列")
-
-<p>Given an array <code>nums</code> of integers, return the <strong>length</strong> of the longest arithmetic subsequence in <code>nums</code>.</p>
-
-<p>Recall that a <em>subsequence</em> of an array <code>nums</code> is a list <code>nums[i<sub>1</sub>], nums[i<sub>2</sub>], ..., nums[i<sub>k</sub>]</code> with <code>0 &lt;= i<sub>1</sub> &lt; i<sub>2</sub> &lt; ... &lt; i<sub>k</sub> &lt;= nums.length - 1</code>, and that a sequence <code>seq</code> is <em>arithmetic</em> if <code>seq[i+1] - seq[i]</code> are all the same value (for <code>0 &lt;= i &lt; seq.length - 1</code>).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,6,9,12]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>
-The whole array is an arithmetic sequence with steps of length = 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,4,7,2,10]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>
-The longest arithmetic subsequence is [4,7,10].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [20,1,15,3,10,5,8]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>
-The longest arithmetic subsequence is [20,15,10,5].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 500</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/longest-chunked-palindrome-decomposition/README.md b/problems/longest-chunked-palindrome-decomposition/README.md
deleted file mode 100644
index 6e555f50b..000000000
--- a/problems/longest-chunked-palindrome-decomposition/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../snapshot-array "Snapshot Array")
-　　　　　　　　　　　　　　　　
-[Next >](../article-views-i "Article Views I")
-
-## [1147. Longest Chunked Palindrome Decomposition (Hard)](https://leetcode.com/problems/longest-chunked-palindrome-decomposition "段式回文")
-
-<p>You are given a string <code>text</code>. You should split it to k substrings <code>(subtext<sub>1</sub>, subtext<sub>2</sub>, ..., subtext<sub>k</sub>)</code> such that:</p>
-
-<ul>
-	<li><code>subtext<sub>i</sub></code> is a <strong>non-empty</strong> string.</li>
-	<li>The concatenation of all the substrings is equal to <code>text</code> (i.e., <code>subtext<sub>1</sub> + subtext<sub>2</sub> + ... + subtext<sub>k</sub> == text</code>).</li>
-	<li><code>subtext<sub>i</sub> == subtext<sub>k - i + 1</sub></code> for all valid values of <code>i</code> (i.e., <code>1 &lt;= i &lt;= k</code>).</li>
-</ul>
-
-<p>Return the largest possible value of <code>k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;ghiabcdefhelloadamhelloabcdefghi&quot;
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> We can split the string on &quot;(ghi)(abcdef)(hello)(adam)(hello)(abcdef)(ghi)&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;merchant&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> We can split the string on &quot;(merchant)&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;antaprezatepzapreanta&quot;
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> We can split the string on &quot;(a)(nt)(a)(pre)(za)(tpe)(za)(pre)(a)(nt)(a)&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= text.length &lt;= 1000</code></li>
-	<li><code>text</code> consists only of lowercase English characters.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Using a rolling hash, we can quickly check whether two strings are equal.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use that as the basis of a dp.
-</details>
diff --git a/problems/longest-common-prefix/README.md b/problems/longest-common-prefix/README.md
deleted file mode 100644
index 9663521b4..000000000
--- a/problems/longest-common-prefix/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../roman-to-integer "Roman to Integer")
-　　　　　　　　　　　　　　　　
-[Next >](../3sum "3Sum")
-
-## [14. Longest Common Prefix (Easy)](https://leetcode.com/problems/longest-common-prefix "最长公共前缀")
-
-<p>Write a function to find the longest common prefix string amongst an array of strings.</p>
-
-<p>If there is no common prefix, return an empty string <code>&quot;&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;flower&quot;,&quot;flow&quot;,&quot;flight&quot;]
-<strong>Output:</strong> &quot;fl&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;dog&quot;,&quot;racecar&quot;,&quot;car&quot;]
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> There is no common prefix among the input strings.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= strs.length &lt;= 200</code></li>
-	<li><code>0 &lt;= strs[i].length &lt;= 200</code></li>
-	<li><code>strs[i]</code> consists of only lower-case English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/longest-common-prefix/longest_common_prefix.go b/problems/longest-common-prefix/longest_common_prefix.go
deleted file mode 100644
index e7b909634..000000000
--- a/problems/longest-common-prefix/longest_common_prefix.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem14
-
-import "strings"
-
-func longestCommonPrefix(strs []string) string {
-	l := len(strs)
-	if l == 0 {
-		return ""
-	}
-	pre := strs[0]
-	for i := 1; i < l; i++ {
-		for strings.Index(strs[i], pre) != 0 {
-			pre = pre[:len(pre)-1]
-		}
-	}
-	return pre
-}
diff --git a/problems/longest-common-prefix/longest_common_prefix_test.go b/problems/longest-common-prefix/longest_common_prefix_test.go
deleted file mode 100644
index 3953de3e3..000000000
--- a/problems/longest-common-prefix/longest_common_prefix_test.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package problem14
-
-import "testing"
-
-type testType struct {
-	in   []string
-	want string
-}
-
-func TestLongestCommonPrefix(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []string{"flower", "flow", "flight"},
-			want: "fl",
-		},
-		{
-			in:   []string{"dog", "race", "car"},
-			want: "",
-		},
-		{
-			in:   nil,
-			want: "",
-		},
-	}
-
-	for _, tt := range tests {
-		got := longestCommonPrefix(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/longest-common-subpath/README.md b/problems/longest-common-subpath/README.md
deleted file mode 100644
index 45d219a2c..000000000
--- a/problems/longest-common-subpath/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-good-numbers "Count Good Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../erect-the-fence-ii "Erect the Fence II")
-
-## [1923. Longest Common Subpath (Hard)](https://leetcode.com/problems/longest-common-subpath "最长公共子路径")
-
-<p>There is a country of <code>n</code> cities numbered from <code>0</code> to <code>n - 1</code>. In this country, there is a road connecting <b>every pair</b> of cities.</p>
-
-<p>There are <code>m</code> friends numbered from <code>0</code> to <code>m - 1</code> who are traveling through the country. Each one of them will take a path consisting of some cities. Each path is represented by an integer array that contains the visited cities in order. The path may contain a city <strong>more than once</strong>, but the same city will not be listed consecutively.</p>
-
-<p>Given an integer <code>n</code> and a 2D integer array <code>paths</code> where <code>paths[i]</code> is an integer array representing the path of the <code>i<sup>th</sup></code> friend, return <em>the length of the <strong>longest common subpath</strong> that is shared by <strong>every</strong> friend&#39;s path, or </em><code>0</code><em> if there is no common subpath at all</em>.</p>
-
-<p>A <strong>subpath</strong> of a path is a contiguous sequence of cities within that path.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, paths = [[0,1,<u>2,3</u>,4],
-                       [<u>2,3</u>,4],
-                       [4,0,1,<u>2,3</u>]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The longest common subpath is [2,3].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, paths = [[0],[1],[2]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no common subpath shared by the three paths.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, paths = [[<u>0</u>,1,2,3,4],
-                       [4,3,2,1,<u>0</u>]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The possible longest common subpaths are [0], [1], [2], [3], and [4]. All have a length of 1.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>m == paths.length</code></li>
-	<li><code>2 &lt;= m &lt;= 10<sup>5</sup></code></li>
-	<li><code>sum(paths[i].length) &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= paths[i][j] &lt; n</code></li>
-	<li>The same city is not listed multiple times consecutively in <code>paths[i]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Suffix Array](../../tag/suffix-array/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If there is a common path with length x, there is for sure a common path of length y where y < x.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can use binary search over the answer with the range [0, min(path[i].length)].
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Using binary search, we want to verify if we have a common path of length m. We can achieve this using hashing.
-</details>
diff --git a/problems/longest-common-subsequence-between-sorted-arrays/README.md b/problems/longest-common-subsequence-between-sorted-arrays/README.md
deleted file mode 100644
index 1477353b8..000000000
--- a/problems/longest-common-subsequence-between-sorted-arrays/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../users-that-actively-request-confirmation-messages "Users That Actively Request Confirmation Messages")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-all-characters-have-equal-number-of-occurrences "Check if All Characters Have Equal Number of Occurrences")
-
-## [1940. Longest Common Subsequence Between Sorted Arrays (Medium)](https://leetcode.com/problems/longest-common-subsequence-between-sorted-arrays "排序数组之间的最长公共子序列")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Merge Two Sorted Lists](../merge-two-sorted-lists) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Fix one array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Choose the next array and get the common elements.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use the common elements as the new fixed array and keep merging with the rest of the arrays.
-</details>
diff --git a/problems/longest-common-subsequence/README.md b/problems/longest-common-subsequence/README.md
deleted file mode 100644
index 25057631a..000000000
--- a/problems/longest-common-subsequence/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../user-activity-for-the-past-30-days-ii "User Activity for the Past 30 Days II")
-　　　　　　　　　　　　　　　　
-[Next >](../decrease-elements-to-make-array-zigzag "Decrease Elements To Make Array Zigzag")
-
-## [1143. Longest Common Subsequence (Medium)](https://leetcode.com/problems/longest-common-subsequence "最长公共子序列")
-
-<p>Given two strings <code>text1</code> and <code>text2</code>, return <em>the length of their longest <strong>common subsequence</strong>. </em>If there is no <strong>common subsequence</strong>, return <code>0</code>.</p>
-
-<p>A <strong>subsequence</strong> of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.</p>
-
-<ul>
-	<li>For example, <code>&quot;ace&quot;</code> is a subsequence of <code>&quot;abcde&quot;</code>.</li>
-</ul>
-
-<p>A <strong>common subsequence</strong> of two strings is a subsequence that is common to both strings.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> text1 = &quot;abcde&quot;, text2 = &quot;ace&quot; 
-<strong>Output:</strong> 3  
-<strong>Explanation:</strong> The longest common subsequence is &quot;ace&quot; and its length is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> text1 = &quot;abc&quot;, text2 = &quot;abc&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The longest common subsequence is &quot;abc&quot; and its length is 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> text1 = &quot;abc&quot;, text2 = &quot;def&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no such common subsequence, so the result is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= text1.length, text2.length &lt;= 1000</code></li>
-	<li><code>text1</code> and <code>text2</code> consist of only lowercase English characters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try dynamic programming. 
-DP[i][j] represents the longest common subsequence of text1[0 ... i] & text2[0 ... j].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-DP[i][j] = DP[i - 1][j - 1] + 1 , if text1[i] == text2[j]
-DP[i][j] = max(DP[i - 1][j], DP[i][j - 1]) , otherwise
-</details>
diff --git a/problems/longest-consecutive-sequence/README.md b/problems/longest-consecutive-sequence/README.md
deleted file mode 100644
index a02d62dc8..000000000
--- a/problems/longest-consecutive-sequence/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-ladder "Word Ladder")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-root-to-leaf-numbers "Sum Root to Leaf Numbers")
-
-## [128. Longest Consecutive Sequence (Medium)](https://leetcode.com/problems/longest-consecutive-sequence "最长连续序列")
-
-<p>Given an unsorted array of integers <code>nums</code>, return <em>the length of the longest consecutive elements sequence.</em></p>
-
-<p>You must write an algorithm that runs in&nbsp;<code>O(n)</code>&nbsp;time.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [100,4,200,1,3,2]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The longest consecutive elements sequence is <code>[1, 2, 3, 4]</code>. Therefore its length is 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,3,7,2,5,8,4,6,0,1]
-<strong>Output:</strong> 9
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Longest Consecutive Sequence](../binary-tree-longest-consecutive-sequence) (Medium)
diff --git a/problems/longest-consecutive-sequence/longest_consecutive_sequence.go b/problems/longest-consecutive-sequence/longest_consecutive_sequence.go
deleted file mode 100644
index 669030c69..000000000
--- a/problems/longest-consecutive-sequence/longest_consecutive_sequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem128
diff --git a/problems/longest-consecutive-sequence/longest_consecutive_sequence_test.go b/problems/longest-consecutive-sequence/longest_consecutive_sequence_test.go
deleted file mode 100644
index 669030c69..000000000
--- a/problems/longest-consecutive-sequence/longest_consecutive_sequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem128
diff --git a/problems/longest-continuous-increasing-subsequence/README.md b/problems/longest-continuous-increasing-subsequence/README.md
deleted file mode 100644
index c3fe206ee..000000000
--- a/problems/longest-continuous-increasing-subsequence/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-longest-increasing-subsequence "Number of Longest Increasing Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../cut-off-trees-for-golf-event "Cut Off Trees for Golf Event")
-
-## [674. Longest Continuous Increasing Subsequence (Easy)](https://leetcode.com/problems/longest-continuous-increasing-subsequence "最长连续递增序列")
-
-<p>Given an unsorted array of integers <code>nums</code>, return <em>the length of the longest <strong>continuous increasing subsequence</strong> (i.e. subarray)</em>. The subsequence must be <strong>strictly</strong> increasing.</p>
-
-<p>A <strong>continuous increasing subsequence</strong> is defined by two indices <code>l</code> and <code>r</code> (<code>l &lt; r</code>) such that it is <code>[nums[l], nums[l + 1], ..., nums[r - 1], nums[r]]</code> and for each <code>l &lt;= i &lt; r</code>, <code>nums[i] &lt; nums[i + 1]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,5,4,7]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The longest continuous increasing subsequence is [1,3,5] with length 3.
-Even though [1,3,5,7] is an increasing subsequence, it is not continuous as elements 5 and 7 are separated by element
-4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,2,2,2]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The longest continuous increasing subsequence is [2] with length 1. Note that it must be strictly
-increasing.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Number of Longest Increasing Subsequence](../number-of-longest-increasing-subsequence) (Medium)
-  1. [Minimum Window Subsequence](../minimum-window-subsequence) (Hard)
diff --git a/problems/longest-continuous-increasing-subsequence/longest_continuous_increasing_subsequence.go b/problems/longest-continuous-increasing-subsequence/longest_continuous_increasing_subsequence.go
deleted file mode 100644
index edecffe10..000000000
--- a/problems/longest-continuous-increasing-subsequence/longest_continuous_increasing_subsequence.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem674
-
-func findLengthOfLCIS(nums []int) int {
-	max, cur := 0, 1
-	for i, v := range nums {
-		if i >= 1 && v > nums[i-1] {
-			cur++
-		} else {
-			cur = 1
-		}
-		if cur > max {
-			max = cur
-		}
-	}
-	return max
-}
diff --git a/problems/longest-continuous-increasing-subsequence/longest_continuous_increasing_subsequence_test.go b/problems/longest-continuous-increasing-subsequence/longest_continuous_increasing_subsequence_test.go
deleted file mode 100644
index fb0f01746..000000000
--- a/problems/longest-continuous-increasing-subsequence/longest_continuous_increasing_subsequence_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem674
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestFindLengthOfLCIS(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 3, 5, 4, 7},
-			want: 3,
-		},
-		{
-			in:   []int{2, 2, 2, 2, 2},
-			want: 1,
-		},
-		{
-			in:   []int{},
-			want: 0,
-		},
-		{
-			in:   []int{1, 3, 5, 7},
-			want: 4,
-		},
-	}
-	for _, tt := range tests {
-		got := findLengthOfLCIS(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit/README.md b/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit/README.md
deleted file mode 100644
index ae7344147..000000000
--- a/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-all-1s-are-at-least-length-k-places-away "Check If All 1's Are at Least Length K Places Away")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows "Find the Kth Smallest Sum of a Matrix With Sorted Rows")
-
-## [1438. Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit (Medium)](https://leetcode.com/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit "绝对差不超过限制的最长连续子数组")
-
-<p>Given an array of integers <code>nums</code> and an integer <code>limit</code>, return the size of the longest <strong>non-empty</strong> subarray such that the absolute difference between any two elements of this subarray is less than or equal to <code>limit</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [8,2,4,7], limit = 4
-<strong>Output:</strong> 2 
-<strong>Explanation:</strong> All subarrays are: 
-[8] with maximum absolute diff |8-8| = 0 &lt;= 4.
-[8,2] with maximum absolute diff |8-2| = 6 &gt; 4. 
-[8,2,4] with maximum absolute diff |8-2| = 6 &gt; 4.
-[8,2,4,7] with maximum absolute diff |8-2| = 6 &gt; 4.
-[2] with maximum absolute diff |2-2| = 0 &lt;= 4.
-[2,4] with maximum absolute diff |2-4| = 2 &lt;= 4.
-[2,4,7] with maximum absolute diff |2-7| = 5 &gt; 4.
-[4] with maximum absolute diff |4-4| = 0 &lt;= 4.
-[4,7] with maximum absolute diff |4-7| = 3 &lt;= 4.
-[7] with maximum absolute diff |7-7| = 0 &lt;= 4. 
-Therefore, the size of the longest subarray is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,1,2,4,7,2], limit = 5
-<strong>Output:</strong> 4 
-<strong>Explanation:</strong> The subarray [2,4,7,2] is the longest since the maximum absolute diff is |2-7| = 5 &lt;= 5.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,2,2,4,4,2,2], limit = 0
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= limit &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Monotonic Queue](../../tag/monotonic-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a sliding window approach keeping the maximum and minimum value using a data structure like a multiset from STL in C++.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-More specifically, use the two pointer technique, moving the right pointer as far as possible to the right until the subarray is not valid (maxValue - minValue > limit), then moving the left pointer until the subarray is valid again (maxValue - minValue <= limit). Keep repeating this process.
-</details>
diff --git a/problems/longest-duplicate-substring/README.md b/problems/longest-duplicate-substring/README.md
deleted file mode 100644
index e3a41f9d7..000000000
--- a/problems/longest-duplicate-substring/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partition-array-for-maximum-sum "Partition Array for Maximum Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../customers-who-bought-all-products "Customers Who Bought All Products")
-
-## [1044. Longest Duplicate Substring (Hard)](https://leetcode.com/problems/longest-duplicate-substring "最长重复子串")
-
-<p>Given a string <code>s</code>, consider all <em>duplicated substrings</em>: (contiguous) substrings of s that occur 2 or more times.&nbsp;The occurrences&nbsp;may overlap.</p>
-
-<p>Return <strong>any</strong> duplicated&nbsp;substring that has the longest possible length.&nbsp;If <code>s</code> does not have a duplicated substring, the answer is <code>&quot;&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "banana"
-<strong>Output:</strong> "ana"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "abcd"
-<strong>Output:</strong> ""
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-  [[Suffix Array](../../tag/suffix-array/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Binary search for the length of the answer.  (If there's an answer of length 10, then there are answers of length 9, 8, 7, ...)
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To check whether an answer of length K exists, we can use Rabin-Karp 's algorithm.
-</details>
diff --git a/problems/longest-duplicate-substring/longest_duplicate_substring.go b/problems/longest-duplicate-substring/longest_duplicate_substring.go
deleted file mode 100644
index c35d6f111..000000000
--- a/problems/longest-duplicate-substring/longest_duplicate_substring.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem1044
-
-func longestDupSubstring(S string) string {
-	res := ""
-
-	isExist := func(L int) bool {
-		seen := make(map[string]bool, len(S)-L+2)
-		for i := 0; i+L <= len(S); i++ {
-			sub := S[i : i+L]
-			if seen[sub] {
-				res = sub
-				return true
-			}
-			seen[sub] = true
-		}
-		return false
-	}
-
-	lo, hi := 0, len(S)
-	for lo < hi {
-		mi := (lo + hi + 1) / 2
-		if isExist(mi) {
-			lo = mi
-		} else {
-			hi = mi - 1
-		}
-	}
-
-	return res
-}
diff --git a/problems/longest-happy-prefix/README.md b/problems/longest-happy-prefix/README.md
deleted file mode 100644
index 7fa67f4df..000000000
--- a/problems/longest-happy-prefix/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-there-is-a-valid-path-in-a-grid "Check if There is a Valid Path in a Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../capital-gainloss "Capital Gain/Loss")
-
-## [1392. Longest Happy Prefix (Hard)](https://leetcode.com/problems/longest-happy-prefix "最长快乐前缀")
-
-<p>A string is called a <strong>happy prefix</strong> if is a <strong>non-empty</strong> prefix which is also a suffix (excluding itself).</p>
-
-<p>Given a string <code>s</code>, return <em>the <strong>longest happy prefix</strong> of</em> <code>s</code>. Return an empty string <code>&quot;&quot;</code> if no such prefix exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;level&quot;
-<strong>Output:</strong> &quot;l&quot;
-<strong>Explanation:</strong> s contains 4 prefix excluding itself (&quot;l&quot;, &quot;le&quot;, &quot;lev&quot;, &quot;leve&quot;), and suffix (&quot;l&quot;, &quot;el&quot;, &quot;vel&quot;, &quot;evel&quot;). The largest prefix which is also suffix is given by &quot;l&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ababab&quot;
-<strong>Output:</strong> &quot;abab&quot;
-<strong>Explanation:</strong> &quot;abab&quot; is the largest prefix which is also suffix. They can overlap in the original string.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use Longest Prefix Suffix (KMP-table) or String Hashing.
-</details>
diff --git a/problems/longest-happy-string/README.md b/problems/longest-happy-string/README.md
deleted file mode 100644
index a07549769..000000000
--- a/problems/longest-happy-string/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-steps-to-reduce-a-number-in-binary-representation-to-one "Number of Steps to Reduce a Number in Binary Representation to One")
-　　　　　　　　　　　　　　　　
-[Next >](../stone-game-iii "Stone Game III")
-
-## [1405. Longest Happy String (Medium)](https://leetcode.com/problems/longest-happy-string "最长快乐字符串")
-
-<p>A string <code>s</code> is called <strong>happy</strong> if it satisfies the following conditions:</p>
-
-<ul>
-	<li><code>s</code> only contains the letters <code>&#39;a&#39;</code>, <code>&#39;b&#39;</code>, and <code>&#39;c&#39;</code>.</li>
-	<li><code>s</code> does not contain any of <code>&quot;aaa&quot;</code>, <code>&quot;bbb&quot;</code>, or <code>&quot;ccc&quot;</code> as a substring.</li>
-	<li><code>s</code> contains <strong>at most</strong> <code>a</code> occurrences of the letter <code>&#39;a&#39;</code>.</li>
-	<li><code>s</code> contains <strong>at most</strong> <code>b</code> occurrences of the letter <code>&#39;b&#39;</code>.</li>
-	<li><code>s</code> contains <strong>at most</strong> <code>c</code> occurrences of the letter <code>&#39;c&#39;</code>.</li>
-</ul>
-
-<p>Given three integers <code>a</code>, <code>b</code>, and <code>c</code>, return <em>the <strong>longest possible happy </strong>string</em>. If there are multiple longest happy strings, return <em>any of them</em>. If there is no such string, return <em>the empty string </em><code>&quot;&quot;</code>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 1, b = 1, c = 7
-<strong>Output:</strong> &quot;ccaccbcc&quot;
-<strong>Explanation:</strong> &quot;ccbccacc&quot; would also be a correct answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 7, b = 1, c = 0
-<strong>Output:</strong> &quot;aabaa&quot;
-<strong>Explanation:</strong> It is the only correct answer in this case.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= a, b, c &lt;= 100</code></li>
-	<li><code>a + b + c &gt; 0</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Reorganize String](../reorganize-string) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a greedy approach.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the letter with the maximum current limit that can be added without breaking the condition.
-</details>
diff --git a/problems/longest-harmonious-subsequence/README.md b/problems/longest-harmonious-subsequence/README.md
deleted file mode 100644
index a965eb210..000000000
--- a/problems/longest-harmonious-subsequence/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-square "Valid Square")
-　　　　　　　　　　　　　　　　
-[Next >](../big-countries "Big Countries")
-
-## [594. Longest Harmonious Subsequence (Easy)](https://leetcode.com/problems/longest-harmonious-subsequence "最长和谐子序列")
-
-<p>We define a harmonious array as an array where the difference between its maximum value and its minimum value is <b>exactly</b> <code>1</code>.</p>
-
-<p>Given an integer array <code>nums</code>, return <em>the length of its longest harmonious subsequence among all its possible subsequences</em>.</p>
-
-<p>A <strong>subsequence</strong> of array is a sequence that can be derived from the array by deleting some or no elements without changing the order of the remaining elements.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,2,2,5,2,3,7]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The longest harmonious subsequence is [3,2,2,2,3].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/longest-harmonious-subsequence/longest_harmonious_subsequence.go b/problems/longest-harmonious-subsequence/longest_harmonious_subsequence.go
deleted file mode 100644
index b3eb6e1e0..000000000
--- a/problems/longest-harmonious-subsequence/longest_harmonious_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem594
diff --git a/problems/longest-harmonious-subsequence/longest_harmonious_subsequence_test.go b/problems/longest-harmonious-subsequence/longest_harmonious_subsequence_test.go
deleted file mode 100644
index b3eb6e1e0..000000000
--- a/problems/longest-harmonious-subsequence/longest_harmonious_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem594
diff --git a/problems/longest-increasing-path-in-a-matrix/README.md b/problems/longest-increasing-path-in-a-matrix/README.md
deleted file mode 100644
index e03319e78..000000000
--- a/problems/longest-increasing-path-in-a-matrix/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../odd-even-linked-list "Odd Even Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../patching-array "Patching Array")
-
-## [329. Longest Increasing Path in a Matrix (Hard)](https://leetcode.com/problems/longest-increasing-path-in-a-matrix "矩阵中的最长递增路径")
-
-<p>Given an <code>m x n</code> integers <code>matrix</code>, return <em>the length of the longest increasing path in </em><code>matrix</code>.</p>
-
-<p>From each cell, you can either move in four directions: left, right, up, or down. You <strong>may not</strong> move <strong>diagonally</strong> or move <strong>outside the boundary</strong> (i.e., wrap-around is not allowed).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/05/grid1.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> matrix = [[9,9,4],[6,6,8],[2,1,1]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The longest increasing path is <code>[1, 2, 6, 9]</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/27/tmp-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> matrix = [[3,4,5],[3,2,6],[2,2,1]]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>The longest increasing path is <code>[3, 4, 5, 6]</code>. Moving diagonally is not allowed.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[1]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>0 &lt;= matrix[i][j] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
diff --git a/problems/longest-increasing-path-in-a-matrix/longest_increasing_path_in_a_matrix.go b/problems/longest-increasing-path-in-a-matrix/longest_increasing_path_in_a_matrix.go
deleted file mode 100644
index d489a341a..000000000
--- a/problems/longest-increasing-path-in-a-matrix/longest_increasing_path_in_a_matrix.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem329
diff --git a/problems/longest-increasing-path-in-a-matrix/longest_increasing_path_in_a_matrix_test.go b/problems/longest-increasing-path-in-a-matrix/longest_increasing_path_in_a_matrix_test.go
deleted file mode 100644
index d489a341a..000000000
--- a/problems/longest-increasing-path-in-a-matrix/longest_increasing_path_in_a_matrix_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem329
diff --git a/problems/longest-increasing-subsequence/README.md b/problems/longest-increasing-subsequence/README.md
deleted file mode 100644
index ee3880e5b..000000000
--- a/problems/longest-increasing-subsequence/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bulls-and-cows "Bulls and Cows")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-invalid-parentheses "Remove Invalid Parentheses")
-
-## [300. Longest Increasing Subsequence (Medium)](https://leetcode.com/problems/longest-increasing-subsequence "最长递增子序列")
-
-<p>Given an integer array <code>nums</code>, return the length of the longest strictly increasing subsequence.</p>
-
-<p>A <strong>subsequence</strong> is a sequence that can be derived from an array by deleting some or no elements without changing the order of the remaining elements. For example, <code>[3,6,2,7]</code> is a subsequence of the array <code>[0,3,1,6,2,2,7]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,9,2,5,3,7,101,18]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The longest increasing subsequence is [2,3,7,101], therefore the length is 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,0,3,2,3]
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,7,7,7,7,7,7]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2500</code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><b>Follow up:</b>&nbsp;Can you come up with an algorithm that runs in&nbsp;<code>O(n log(n))</code> time complexity?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Increasing Triplet Subsequence](../increasing-triplet-subsequence) (Medium)
-  1. [Russian Doll Envelopes](../russian-doll-envelopes) (Hard)
-  1. [Maximum Length of Pair Chain](../maximum-length-of-pair-chain) (Medium)
-  1. [Number of Longest Increasing Subsequence](../number-of-longest-increasing-subsequence) (Medium)
-  1. [Minimum ASCII Delete Sum for Two Strings](../minimum-ascii-delete-sum-for-two-strings) (Medium)
-  1. [Minimum Number of Removals to Make Mountain Array](../minimum-number-of-removals-to-make-mountain-array) (Hard)
-  1. [Find the Longest Valid Obstacle Course at Each Position](../find-the-longest-valid-obstacle-course-at-each-position) (Hard)
diff --git a/problems/longest-increasing-subsequence/longest_increasing_subsequence.go b/problems/longest-increasing-subsequence/longest_increasing_subsequence.go
deleted file mode 100644
index 12378f915..000000000
--- a/problems/longest-increasing-subsequence/longest_increasing_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem300
diff --git a/problems/longest-increasing-subsequence/longest_increasing_subsequence_test.go b/problems/longest-increasing-subsequence/longest_increasing_subsequence_test.go
deleted file mode 100644
index 12378f915..000000000
--- a/problems/longest-increasing-subsequence/longest_increasing_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem300
diff --git a/problems/longest-line-of-consecutive-one-in-matrix/README.md b/problems/longest-line-of-consecutive-one-in-matrix/README.md
deleted file mode 100644
index a6ea512dd..000000000
--- a/problems/longest-line-of-consecutive-one-in-matrix/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../array-partition-i "Array Partition I")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-tilt "Binary Tree Tilt")
-
-## [562. Longest Line of Consecutive One in Matrix (Medium)](https://leetcode.com/problems/longest-line-of-consecutive-one-in-matrix "矩阵中最长的连续1线段")
-
-Given a 01 matrix <b>M</b>, find the longest line of consecutive one in the matrix. The line could be horizontal, vertical, diagonal or anti-diagonal.
-
-<p><b>Example:</b><br />
-<pre>
-<b>Input:</b>
-[[0,1,1,0],
- [0,1,1,0],
- [0,0,0,1]]
-<b>Output:</b> 3
-</pre>
-</p>
-
-<p>
-<b>Hint:</b>
-The number of elements in the given matrix will not exceed 10,000.
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-One solution is to count ones in each direction separately and find the longest line. Don't you think  it will take too much lines of code?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is it possible to use some extra space to make the solution simple?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Can we use dynamic programming to make use of intermediate results?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Think of a 3D array which can be used to store the longest line obtained so far for each direction.
-</details>
diff --git a/problems/longest-line-of-consecutive-one-in-matrix/longest_line_of_consecutive_one_in_matrix.go b/problems/longest-line-of-consecutive-one-in-matrix/longest_line_of_consecutive_one_in_matrix.go
deleted file mode 100644
index aa5027dbc..000000000
--- a/problems/longest-line-of-consecutive-one-in-matrix/longest_line_of_consecutive_one_in_matrix.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem562
diff --git a/problems/longest-line-of-consecutive-one-in-matrix/longest_line_of_consecutive_one_in_matrix_test.go b/problems/longest-line-of-consecutive-one-in-matrix/longest_line_of_consecutive_one_in_matrix_test.go
deleted file mode 100644
index aa5027dbc..000000000
--- a/problems/longest-line-of-consecutive-one-in-matrix/longest_line_of_consecutive_one_in_matrix_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem562
diff --git a/problems/longest-mountain-in-array/README.md b/problems/longest-mountain-in-array/README.md
deleted file mode 100644
index c391abf44..000000000
--- a/problems/longest-mountain-in-array/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../backspace-string-compare "Backspace String Compare")
-　　　　　　　　　　　　　　　　
-[Next >](../hand-of-straights "Hand of Straights")
-
-## [845. Longest Mountain in Array (Medium)](https://leetcode.com/problems/longest-mountain-in-array "数组中的最长山脉")
-
-<p>You may recall that an array <code>arr</code> is a <strong>mountain array</strong> if and only if:</p>
-
-<ul>
-	<li><code>arr.length &gt;= 3</code></li>
-	<li>There exists some index <code>i</code> (<strong>0-indexed</strong>) with <code>0 &lt; i &lt; arr.length - 1</code> such that:
-	<ul>
-		<li><code>arr[0] &lt; arr[1] &lt; ... &lt; arr[i - 1] &lt; arr[i]</code></li>
-		<li><code>arr[i] &gt; arr[i + 1] &gt; ... &gt; arr[arr.length - 1]</code></li>
-	</ul>
-	</li>
-</ul>
-
-<p>Given an integer array <code>arr</code>, return <em>the length of the longest subarray, which is a mountain</em>. Return <code>0</code> if there is no mountain subarray.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,1,4,7,3,2,5]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The largest mountain is [1,4,7,3,2] which has length 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,2,2]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no mountain.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>Can you solve it using only one pass?</li>
-	<li>Can you solve it in <code>O(1)</code> space?</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
diff --git a/problems/longest-mountain-in-array/longest_mountain_in_array.go b/problems/longest-mountain-in-array/longest_mountain_in_array.go
deleted file mode 100644
index 684feeee7..000000000
--- a/problems/longest-mountain-in-array/longest_mountain_in_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem845
diff --git a/problems/longest-mountain-in-array/longest_mountain_in_array_test.go b/problems/longest-mountain-in-array/longest_mountain_in_array_test.go
deleted file mode 100644
index 684feeee7..000000000
--- a/problems/longest-mountain-in-array/longest_mountain_in_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem845
diff --git a/problems/longest-nice-substring/README.md b/problems/longest-nice-substring/README.md
deleted file mode 100644
index 20b09a0f5..000000000
--- a/problems/longest-nice-substring/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../buildings-with-an-ocean-view "Buildings With an Ocean View")
-　　　　　　　　　　　　　　　　
-[Next >](../form-array-by-concatenating-subarrays-of-another-array "Form Array by Concatenating Subarrays of Another Array")
-
-## [1763. Longest Nice Substring (Easy)](https://leetcode.com/problems/longest-nice-substring "最长的美好子字符串")
-
-<p>A string <code>s</code> is <strong>nice</strong> if, for every letter of the alphabet that <code>s</code> contains, it appears <strong>both</strong> in uppercase and lowercase. For example, <code>&quot;abABB&quot;</code> is nice because <code>&#39;A&#39;</code> and <code>&#39;a&#39;</code> appear, and <code>&#39;B&#39;</code> and <code>&#39;b&#39;</code> appear. However, <code>&quot;abA&quot;</code> is not because <code>&#39;b&#39;</code> appears, but <code>&#39;B&#39;</code> does not.</p>
-
-<p>Given a string <code>s</code>, return <em>the longest <strong>substring</strong> of <code>s</code> that is <strong>nice</strong>. If there are multiple, return the substring of the <strong>earliest</strong> occurrence. If there are none, return an empty string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;YazaAay&quot;
-<strong>Output:</strong> &quot;aAa&quot;
-<strong>Explanation: </strong>&quot;aAa&quot; is a nice string because &#39;A/a&#39; is the only letter of the alphabet in s, and both &#39;A&#39; and &#39;a&#39; appear.
-&quot;aAa&quot; is the longest nice substring.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;Bb&quot;
-<strong>Output:</strong> &quot;Bb&quot;
-<strong>Explanation:</strong> &quot;Bb&quot; is a nice string because both &#39;B&#39; and &#39;b&#39; appear. The whole string is a substring.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;c&quot;
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> There are no nice substrings.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> consists of uppercase and lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Brute force and check each substring to see if it is nice.
-</details>
diff --git a/problems/longest-palindrome-by-concatenating-two-letter-words/README.md b/problems/longest-palindrome-by-concatenating-two-letter-words/README.md
deleted file mode 100644
index 3efa72307..000000000
--- a/problems/longest-palindrome-by-concatenating-two-letter-words/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-twin-sum-of-a-linked-list "Maximum Twin Sum of a Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../stamping-the-grid "Stamping the Grid")
-
-## [2131. Longest Palindrome by Concatenating Two Letter Words (Medium)](https://leetcode.com/problems/longest-palindrome-by-concatenating-two-letter-words "连接两字母单词得到的最长回文串")
-
-<p>You are given an array of strings <code>words</code>. Each element of <code>words</code> consists of <strong>two</strong> lowercase English letters.</p>
-
-<p>Create the <strong>longest possible palindrome</strong> by selecting some elements from <code>words</code> and concatenating them in <strong>any order</strong>. Each element can be selected <strong>at most once</strong>.</p>
-
-<p>Return <em>the <strong>length</strong> of the longest palindrome that you can create</em>. If it is impossible to create any palindrome, return <code>0</code>.</p>
-
-<p>A <strong>palindrome</strong> is a string that reads the same forward and backward.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;lc&quot;,&quot;cl&quot;,&quot;gg&quot;]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> One longest palindrome is &quot;lc&quot; + &quot;gg&quot; + &quot;cl&quot; = &quot;lcggcl&quot;, of length 6.
-Note that &quot;clgglc&quot; is another longest palindrome that can be created.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;ab&quot;,&quot;ty&quot;,&quot;yt&quot;,&quot;lc&quot;,&quot;cl&quot;,&quot;ab&quot;]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> One longest palindrome is &quot;ty&quot; + &quot;lc&quot; + &quot;cl&quot; + &quot;yt&quot; = &quot;tylcclyt&quot;, of length 8.
-Note that &quot;lcyttycl&quot; is another longest palindrome that can be created.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;cc&quot;,&quot;ll&quot;,&quot;xx&quot;]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> One longest palindrome is &quot;cc&quot;, of length 2.
-Note that &quot;ll&quot; is another longest palindrome that can be created, and so is &quot;xx&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>words[i].length == 2</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A palindrome must be mirrored over the center. Suppose we have a palindrome. If we prepend the word "ab" on the left, what must we append on the right to keep it a palindrome?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We must append "ba" on the right. The number of times we can do this is the minimum of (occurrences of "ab") and (occurrences of "ba").
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For words that are already palindromes, e.g. "aa", we can prepend and append these in pairs as described in the previous hint. We can also use exactly one in the middle to form an even longer palindrome.
-</details>
diff --git a/problems/longest-palindrome/README.md b/problems/longest-palindrome/README.md
deleted file mode 100644
index 3081419ec..000000000
--- a/problems/longest-palindrome/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-word-abbreviation "Valid Word Abbreviation")
-　　　　　　　　　　　　　　　　
-[Next >](../split-array-largest-sum "Split Array Largest Sum")
-
-## [409. Longest Palindrome (Easy)](https://leetcode.com/problems/longest-palindrome "最长回文串")
-
-<p>Given a string <code>s</code> which consists of lowercase or uppercase letters, return <em>the length of the <strong>longest palindrome</strong></em>&nbsp;that can be built with those letters.</p>
-
-<p>Letters are <strong>case sensitive</strong>, for example,&nbsp;<code>&quot;Aa&quot;</code> is not considered a palindrome here.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abccccdd&quot;
-<strong>Output:</strong> 7
-<strong>Explanation:</strong>
-One longest palindrome that can be built is &quot;dccaccd&quot;, whose length is 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bb&quot;
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 2000</code></li>
-	<li><code>s</code> consists of lowercase <strong>and/or</strong> uppercase English&nbsp;letters only.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Palindrome Permutation](../palindrome-permutation) (Easy)
diff --git a/problems/longest-palindrome/longest_palindrome.go b/problems/longest-palindrome/longest_palindrome.go
deleted file mode 100644
index e7796f4c5..000000000
--- a/problems/longest-palindrome/longest_palindrome.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem409
diff --git a/problems/longest-palindrome/longest_palindrome_test.go b/problems/longest-palindrome/longest_palindrome_test.go
deleted file mode 100644
index e7796f4c5..000000000
--- a/problems/longest-palindrome/longest_palindrome_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem409
diff --git a/problems/longest-palindromic-subsequence-ii/README.md b/problems/longest-palindromic-subsequence-ii/README.md
deleted file mode 100644
index 7f8a858a1..000000000
--- a/problems/longest-palindromic-subsequence-ii/README.md
+++ /dev/null
@@ -1,32 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-incompatibility "Minimum Incompatibility")
-　　　　　　　　　　　　　　　　
-[Next >](../invalid-tweets "Invalid Tweets")
-
-## [1682. Longest Palindromic Subsequence II (Medium)](https://leetcode.com/problems/longest-palindromic-subsequence-ii "最长回文子序列 II")
-
-
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Longest Palindromic Subsequence](../longest-palindromic-subsequence) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-As with any good dp problem that uses palindromes, try building the palindrome from the edges
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The prime point is to check that no two adjacent characters are equal, so save the past character while building the palindrome.
-</details>
diff --git a/problems/longest-palindromic-subsequence/README.md b/problems/longest-palindromic-subsequence/README.md
deleted file mode 100644
index 7ba508696..000000000
--- a/problems/longest-palindromic-subsequence/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-largest-value-in-each-tree-row "Find Largest Value in Each Tree Row")
-　　　　　　　　　　　　　　　　
-[Next >](../super-washing-machines "Super Washing Machines")
-
-## [516. Longest Palindromic Subsequence (Medium)](https://leetcode.com/problems/longest-palindromic-subsequence "最长回文子序列")
-
-<p>Given a string <code>s</code>, find <em>the longest palindromic <strong>subsequence</strong>&#39;s length in</em> <code>s</code>.</p>
-
-<p>A <strong>subsequence</strong> is a sequence that can be derived from another sequence by deleting some or no elements without changing the order of the remaining elements.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bbbab&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> One possible longest palindromic subsequence is &quot;bbbb&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cbbd&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> One possible longest palindromic subsequence is &quot;bb&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> consists only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Longest Palindromic Substring](../longest-palindromic-substring) (Medium)
-  1. [Palindromic Substrings](../palindromic-substrings) (Medium)
-  1. [Count Different Palindromic Subsequences](../count-different-palindromic-subsequences) (Hard)
-  1. [Longest Common Subsequence](../longest-common-subsequence) (Medium)
-  1. [Longest Palindromic Subsequence II](../longest-palindromic-subsequence-ii) (Medium)
-  1. [Maximize Palindrome Length From Subsequences](../maximize-palindrome-length-from-subsequences) (Hard)
-  1. [Maximum Product of the Length of Two Palindromic Subsequences](../maximum-product-of-the-length-of-two-palindromic-subsequences) (Medium)
diff --git a/problems/longest-palindromic-subsequence/longest_palindromic_subsequence.go b/problems/longest-palindromic-subsequence/longest_palindromic_subsequence.go
deleted file mode 100644
index bd5e860fe..000000000
--- a/problems/longest-palindromic-subsequence/longest_palindromic_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem516
diff --git a/problems/longest-palindromic-subsequence/longest_palindromic_subsequence_test.go b/problems/longest-palindromic-subsequence/longest_palindromic_subsequence_test.go
deleted file mode 100644
index bd5e860fe..000000000
--- a/problems/longest-palindromic-subsequence/longest_palindromic_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem516
diff --git a/problems/longest-palindromic-substring/README.md b/problems/longest-palindromic-substring/README.md
deleted file mode 100644
index 9e3b74a31..000000000
--- a/problems/longest-palindromic-substring/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../median-of-two-sorted-arrays "Median of Two Sorted Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../zigzag-conversion "Zigzag Conversion")
-
-## [5. Longest Palindromic Substring (Medium)](https://leetcode.com/problems/longest-palindromic-substring "最长回文子串")
-
-<p>Given a string <code>s</code>, return&nbsp;<em>the longest palindromic substring</em> in <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;babad&quot;
-<strong>Output:</strong> &quot;bab&quot;
-<strong>Note:</strong> &quot;aba&quot; is also a valid answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cbbd&quot;
-<strong>Output:</strong> &quot;bb&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a&quot;
-<strong>Output:</strong> &quot;a&quot;
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ac&quot;
-<strong>Output:</strong> &quot;a&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> consist of only digits and English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Shortest Palindrome](../shortest-palindrome) (Hard)
-  1. [Palindrome Permutation](../palindrome-permutation) (Easy)
-  1. [Palindrome Pairs](../palindrome-pairs) (Hard)
-  1. [Longest Palindromic Subsequence](../longest-palindromic-subsequence) (Medium)
-  1. [Palindromic Substrings](../palindromic-substrings) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can we reuse a previously computed palindrome to compute a larger palindrome?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If “aba” is a palindrome, is “xabax” a palindrome? Similarly is “xabay” a palindrome?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Complexity based hint:</br>
-If we use brute-force and check whether for every start and end position a substring is a palindrome we have O(n^2) start - end pairs and O(n) palindromic checks. Can we reduce the time for palindromic checks to O(1) by reusing some previous computation.
-</details>
diff --git a/problems/longest-palindromic-substring/longest_palindromic_substring.go b/problems/longest-palindromic-substring/longest_palindromic_substring.go
deleted file mode 100644
index 105c263a5..000000000
--- a/problems/longest-palindromic-substring/longest_palindromic_substring.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem5
-
-func longestPalindrome(s string) string {
-	start, maxLen, l := 0, 0, len(s)
-	for i := 0; i < l; i++ {
-		expandAroundCenter(s, i, i, &start, &maxLen)
-		expandAroundCenter(s, i, i+1, &start, &maxLen)
-	}
-	return s[start : start+maxLen]
-}
-
-func expandAroundCenter(s string, l, r int, start, maxLen *int) {
-	for l >= 0 && r < len(s) && s[l] == s[r] {
-		l, r = l-1, r+1
-	}
-	if r-l-1 > *maxLen {
-		*maxLen = r - l - 1
-		*start = l + 1
-	}
-}
diff --git a/problems/longest-palindromic-substring/longest_palindromic_substring_test.go b/problems/longest-palindromic-substring/longest_palindromic_substring_test.go
deleted file mode 100644
index 60612ce84..000000000
--- a/problems/longest-palindromic-substring/longest_palindromic_substring_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem5
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestLongestPalindrome(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "babad",
-			want: "bab",
-		},
-		{
-			in:   "cbbd",
-			want: "bb",
-		},
-		{
-			in:   "",
-			want: "",
-		},
-		{
-			in:   "a",
-			want: "a",
-		},
-		{
-			in:   "abbba",
-			want: "abbba",
-		},
-	}
-	for _, tt := range tests {
-		got := longestPalindrome(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/longest-repeating-character-replacement/README.md b/problems/longest-repeating-character-replacement/README.md
deleted file mode 100644
index 650562490..000000000
--- a/problems/longest-repeating-character-replacement/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reconstruct-original-digits-from-english "Reconstruct Original Digits from English")
-　　　　　　　　　　　　　　　　
-[Next >](../word-squares "Word Squares")
-
-## [424. Longest Repeating Character Replacement (Medium)](https://leetcode.com/problems/longest-repeating-character-replacement "替换后的最长重复字符")
-
-<p>You are given a string <code>s</code> and an integer <code>k</code>. You can choose any character of the string and change it to any other uppercase English character. You can perform this operation at most <code>k</code> times.</p>
-
-<p>Return <em>the length of the longest substring containing the same letter you can get after performing the above operations</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ABAB&quot;, k = 2
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Replace the two &#39;A&#39;s with two &#39;B&#39;s or vice versa.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;AABABBA&quot;, k = 1
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Replace the one &#39;A&#39; in the middle with &#39;B&#39; and form &quot;AABBBBA&quot;.
-The substring &quot;BBBB&quot; has the longest repeating letters, which is 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of only uppercase English letters.</li>
-	<li><code>0 &lt;= k &lt;= s.length</code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Longest Substring with At Most K Distinct Characters](../longest-substring-with-at-most-k-distinct-characters) (Medium)
-  1. [Max Consecutive Ones III](../max-consecutive-ones-iii) (Medium)
-  1. [Minimum Number of Operations to Make Array Continuous](../minimum-number-of-operations-to-make-array-continuous) (Hard)
-  1. [Maximize the Confusion of an Exam](../maximize-the-confusion-of-an-exam) (Medium)
diff --git a/problems/longest-repeating-character-replacement/longest_repeating_character_replacement.go b/problems/longest-repeating-character-replacement/longest_repeating_character_replacement.go
deleted file mode 100644
index 40325c694..000000000
--- a/problems/longest-repeating-character-replacement/longest_repeating_character_replacement.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem424
diff --git a/problems/longest-repeating-character-replacement/longest_repeating_character_replacement_test.go b/problems/longest-repeating-character-replacement/longest_repeating_character_replacement_test.go
deleted file mode 100644
index 40325c694..000000000
--- a/problems/longest-repeating-character-replacement/longest_repeating_character_replacement_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem424
diff --git a/problems/longest-repeating-substring/README.md b/problems/longest-repeating-substring/README.md
deleted file mode 100644
index 0f83a9c26..000000000
--- a/problems/longest-repeating-substring/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lexicographically-smallest-equivalent-string "Lexicographically Smallest Equivalent String")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-valid-subarrays "Number of Valid Subarrays")
-
-## [1062. Longest Repeating Substring (Medium)](https://leetcode.com/problems/longest-repeating-substring "最长重复子串")
-
-<p>Given a string <code>S</code>, find out the length of the longest repeating substring(s). Return <code>0</code> if no repeating substring exists.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">&quot;abcd&quot;</span>
-<strong>Output: </strong><span id="example-output-1">0</span>
-<strong>Explanation: </strong>There is no repeating substring.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">&quot;abbaba&quot;</span>
-<strong>Output: </strong><span id="example-output-2">2</span>
-<strong>Explanation: </strong>The longest repeating substrings are &quot;ab&quot; and &quot;ba&quot;, each of which occurs twice.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-3-1">&quot;aabcaabdaab&quot;</span>
-<strong>Output: </strong><span id="example-output-3">3</span>
-<strong>Explanation: </strong>The longest repeating substring is &quot;aab&quot;, which occurs <code>3</code> times.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-4-1">&quot;aaaaa&quot;</span>
-<strong>Output: </strong><span id="example-output-4">4</span>
-<strong>Explanation: </strong>The longest repeating substring is &quot;aaaa&quot;, which occurs twice.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>The string <code>S</code> consists of only lowercase English letters from <code>&#39;a&#39;</code> - <code>&#39;z&#39;</code>.</li>
-	<li><code>1 &lt;= S.length &lt;= 1500</code></li>
-</ol>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Suffix Array](../../tag/suffix-array/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Generate all substrings in O(N^2) time with hashing.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Choose those hashing of strings with the largest length.
-</details>
diff --git a/problems/longest-string-chain/README.md b/problems/longest-string-chain/README.md
deleted file mode 100644
index d659234b5..000000000
--- a/problems/longest-string-chain/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-all-adjacent-duplicates-in-string "Remove All Adjacent Duplicates In String")
-　　　　　　　　　　　　　　　　
-[Next >](../last-stone-weight-ii "Last Stone Weight II")
-
-## [1048. Longest String Chain (Medium)](https://leetcode.com/problems/longest-string-chain "最长字符串链")
-
-<p>You are given an array of <code>words</code> where each word consists of lowercase English letters.</p>
-
-<p><code>word<sub>A</sub></code> is a <strong>predecessor</strong> of <code>word<sub>B</sub></code> if and only if we can insert <strong>exactly one</strong> letter anywhere in <code>word<sub>A</sub></code> <strong>without changing the order of the other characters</strong> to make it equal to <code>word<sub>B</sub></code>.</p>
-
-<ul>
-	<li>For example, <code>&quot;abc&quot;</code> is a <strong>predecessor</strong> of <code>&quot;ab<u>a</u>c&quot;</code>, while <code>&quot;cba&quot;</code> is not a <strong>predecessor</strong> of <code>&quot;bcad&quot;</code>.</li>
-</ul>
-
-<p>A <strong>word chain</strong><em> </em>is a sequence of words <code>[word<sub>1</sub>, word<sub>2</sub>, ..., word<sub>k</sub>]</code> with <code>k &gt;= 1</code>, where <code>word<sub>1</sub></code> is a <strong>predecessor</strong> of <code>word<sub>2</sub></code>, <code>word<sub>2</sub></code> is a <strong>predecessor</strong> of <code>word<sub>3</sub></code>, and so on. A single word is trivially a <strong>word chain</strong> with <code>k == 1</code>.</p>
-
-<p>Return <em>the <strong>length</strong> of the <strong>longest possible word chain</strong> with words chosen from the given list of </em><code>words</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;a&quot;,&quot;b&quot;,&quot;ba&quot;,&quot;bca&quot;,&quot;bda&quot;,&quot;bdca&quot;]
-<strong>Output:</strong> 4
-<strong>Explanation</strong>: One of the longest word chains is [&quot;a&quot;,&quot;<u>b</u>a&quot;,&quot;b<u>d</u>a&quot;,&quot;bd<u>c</u>a&quot;].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;xbc&quot;,&quot;pcxbcf&quot;,&quot;xb&quot;,&quot;cxbc&quot;,&quot;pcxbc&quot;]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> All the words can be put in a word chain [&quot;xb&quot;, &quot;xb<u>c</u>&quot;, &quot;<u>c</u>xbc&quot;, &quot;<u>p</u>cxbc&quot;, &quot;pcxbc<u>f</u>&quot;].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;abcd&quot;,&quot;dbqca&quot;]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The trivial word chain [&quot;abcd&quot;] is one of the longest word chains.
-[&quot;abcd&quot;,&quot;dbqca&quot;] is not a valid word chain because the ordering of the letters is changed.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 16</code></li>
-	<li><code>words[i]</code> only consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Instead of adding a character, try deleting a character to form a chain in reverse.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each word in order of length, for each word2 which is word with one character removed, length[word2] = max(length[word2], length[word] + 1).
-</details>
diff --git a/problems/longest-string-chain/longest_string_chain.go b/problems/longest-string-chain/longest_string_chain.go
deleted file mode 100644
index 48f2ffe95..000000000
--- a/problems/longest-string-chain/longest_string_chain.go
+++ /dev/null
@@ -1,54 +0,0 @@
-package problem1048
-
-func longestStrChain(words []string) int {
-	indexs := make([][]int, 17)
-	count := make([]int, len(words))
-	for i, word := range words {
-		l := len(word)
-		indexs[l] = append(indexs[l], i)
-		count[i] = 1
-	}
-
-	res := 1
-	for length := 1; length+1 <= 16; length++ {
-		for _, i := range indexs[length] {
-			for _, j := range indexs[length+1] {
-				if count[j] > count[i] {
-					// because of isPredecessor is expensive
-					continue
-				}
-				if isPredecessor(words[i], words[j]) {
-					count[j] = count[i] + 1
-				}
-			}
-		}
-	}
-
-	for _, v := range count {
-		res = max(res, v)
-	}
-	return res
-}
-
-func isPredecessor(w1, w2 string) bool {
-	n := len(w1)
-	diff := 0
-	i, j := 0, 0
-	for i < n && diff <= 1 {
-		if w1[i] != w2[j] {
-			diff++
-		} else {
-			i++
-		}
-		j++
-	}
-	return diff == 1 ||
-		i == j // w1[:i]==w2[:i]
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/longest-subarray-of-1s-after-deleting-one-element/README.md b/problems/longest-subarray-of-1s-after-deleting-one-element/README.md
deleted file mode 100644
index 4c5892b99..000000000
--- a/problems/longest-subarray-of-1s-after-deleting-one-element/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-kth-factor-of-n "The kth Factor of n")
-　　　　　　　　　　　　　　　　
-[Next >](../parallel-courses-ii "Parallel Courses II")
-
-## [1493. Longest Subarray of 1's After Deleting One Element (Medium)](https://leetcode.com/problems/longest-subarray-of-1s-after-deleting-one-element "删掉一个元素以后全为 1 的最长子数组")
-
-<p>Given a binary array <code>nums</code>, you should delete one element from it.</p>
-
-<p>Return <em>the size of the longest non-empty subarray containing only </em><code>1</code><em>&#39;s in the resulting array</em>. Return <code>0</code> if there is no such subarray.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,0,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> After deleting the number in position 2, [1,1,1] contains 3 numbers with value of 1&#39;s.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,1,1,0,1,1,0,1]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> After deleting the number in position 4, [0,1,1,1,1,1,0,1] longest subarray with value of 1&#39;s is [1,1,1,1,1].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You must delete one element.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums[i]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Maintain a sliding window where there is at most one zero on it.
-</details>
diff --git a/problems/longest-subsequence-repeated-k-times/README.md b/problems/longest-subsequence-repeated-k-times/README.md
deleted file mode 100644
index 2879b957e..000000000
--- a/problems/longest-subsequence-repeated-k-times/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../detect-squares "Detect Squares")
-　　　　　　　　　　　　　　　　
-[Next >](../average-height-of-buildings-in-each-segment "Average Height of Buildings in Each Segment")
-
-## [2014. Longest Subsequence Repeated k Times (Hard)](https://leetcode.com/problems/longest-subsequence-repeated-k-times "重复 K 次的最长子序列")
-
-<p>You are given a string <code>s</code> of length <code>n</code>, and an integer <code>k</code>. You are tasked to find the <strong>longest subsequence repeated</strong> <code>k</code> times in string <code>s</code>.</p>
-
-<p>A <strong>subsequence</strong> is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters.</p>
-
-<p>A subsequence <code>seq</code> is <strong>repeated</strong> <code>k</code> times in the string <code>s</code> if <code>seq * k</code> is a subsequence of <code>s</code>, where <code>seq * k</code> represents a string constructed by concatenating <code>seq</code> <code>k</code> times.</p>
-
-<ul>
-	<li>For example, <code>&quot;bba&quot;</code> is repeated <code>2</code> times in the string <code>&quot;bababcba&quot;</code>, because the string <code>&quot;bbabba&quot;</code>, constructed by concatenating <code>&quot;bba&quot;</code> <code>2</code> times, is a subsequence of the string <code>&quot;<strong><u>b</u></strong>a<strong><u>bab</u></strong>c<strong><u>ba</u></strong>&quot;</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>longest subsequence repeated</strong> </em><code>k</code><em> times in string </em><code>s</code><em>. If multiple such subsequences are found, return the <strong>lexicographically largest</strong> one. If there is no such subsequence, return an <strong>empty</strong> string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="example 1" src="https://assets.leetcode.com/uploads/2021/08/30/longest-subsequence-repeat-k-times.png" style="width: 457px; height: 99px;" />
-<pre>
-<strong>Input:</strong> s = &quot;letsleetcode&quot;, k = 2
-<strong>Output:</strong> &quot;let&quot;
-<strong>Explanation:</strong> There are two longest subsequences repeated 2 times: &quot;let&quot; and &quot;ete&quot;.
-&quot;let&quot; is the lexicographically largest one.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bb&quot;, k = 2
-<strong>Output:</strong> &quot;b&quot;
-<strong>Explanation:</strong> The longest subsequence repeated 2 times is &quot;b&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ab&quot;, k = 2
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> There is no subsequence repeated 2 times. Empty string is returned.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == s.length</code></li>
-	<li><code>2 &lt;= n, k &lt;= 2000</code></li>
-	<li><code>2 &lt;= n &lt; k * 8</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The length of the longest subsequence does not exceed n/k. Do you know why?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the characters that could be included in the potential answer. A character occurring more than or equal to k times can be used in the answer up to (count of the character / k) times.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Try all possible candidates in reverse lexicographic order, and check the string for the subsequence condition.
-</details>
diff --git a/problems/longest-substring-of-all-vowels-in-order/README.md b/problems/longest-substring-of-all-vowels-in-order/README.md
deleted file mode 100644
index c3cb2938b..000000000
--- a/problems/longest-substring-of-all-vowels-in-order/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../frequency-of-the-most-frequent-element "Frequency of the Most Frequent Element")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-building-height "Maximum Building Height")
-
-## [1839. Longest Substring Of All Vowels in Order (Medium)](https://leetcode.com/problems/longest-substring-of-all-vowels-in-order "所有元音按顺序排布的最长子字符串")
-
-<p>A string is considered <strong>beautiful</strong> if it satisfies the following conditions:</p>
-
-<ul>
-	<li>Each of the 5 English vowels (<code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, <code>&#39;u&#39;</code>) must appear <strong>at least once</strong> in it.</li>
-	<li>The letters must be sorted in <strong>alphabetical order</strong> (i.e. all <code>&#39;a&#39;</code>s before <code>&#39;e&#39;</code>s, all <code>&#39;e&#39;</code>s before <code>&#39;i&#39;</code>s, etc.).</li>
-</ul>
-
-<p>For example, strings <code>&quot;aeiou&quot;</code> and <code>&quot;aaaaaaeiiiioou&quot;</code> are considered <strong>beautiful</strong>, but <code>&quot;uaeio&quot;</code>, <code>&quot;aeoiu&quot;</code>, and <code>&quot;aaaeeeooo&quot;</code> are <strong>not beautiful</strong>.</p>
-
-<p>Given a string <code>word</code> consisting of English vowels, return <em>the <strong>length of the longest beautiful substring</strong> of </em><code>word</code><em>. If no such substring exists, return </em><code>0</code>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters in a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;aeiaaio<u>aaaaeiiiiouuu</u>ooaauuaeiu&quot;
-<strong>Output:</strong> 13
-<b>Explanation:</b> The longest beautiful substring in word is &quot;aaaaeiiiiouuu&quot; of length 13.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;aeeeiiiioooauuu<u>aeiou</u>&quot;
-<strong>Output:</strong> 5
-<b>Explanation:</b> The longest beautiful substring in word is &quot;aeiou&quot; of length 5.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;a&quot;
-<strong>Output:</strong> 0
-<b>Explanation:</b> There is no beautiful substring, so return 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length &lt;= 5 * 10<sup>5</sup></code></li>
-	<li><code>word</code> consists of characters <code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, and <code>&#39;u&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Start from each 'a' and find the longest beautiful substring starting at that index.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Based on the current character decide if you should include the next character in the beautiful substring.
-</details>
diff --git a/problems/longest-substring-with-at-least-k-repeating-characters/README.md b/problems/longest-substring-with-at-least-k-repeating-characters/README.md
deleted file mode 100644
index 399a1e0f2..000000000
--- a/problems/longest-substring-with-at-least-k-repeating-characters/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decode-string "Decode String")
-　　　　　　　　　　　　　　　　
-[Next >](../rotate-function "Rotate Function")
-
-## [395. Longest Substring with At Least K Repeating Characters (Medium)](https://leetcode.com/problems/longest-substring-with-at-least-k-repeating-characters "至少有 K 个重复字符的最长子串")
-
-<p>Given a string <code>s</code> and an integer <code>k</code>, return <em>the length of the longest substring of</em> <code>s</code> <em>such that the frequency of each character in this substring is greater than or equal to</em> <code>k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaabb&quot;, k = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The longest substring is &quot;aaa&quot;, as &#39;a&#39; is repeated 3 times.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ababbc&quot;, k = 2
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The longest substring is &quot;ababb&quot;, as &#39;a&#39; is repeated 2 times and &#39;b&#39; is repeated 3 times.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Longest Subsequence Repeated k Times](../longest-subsequence-repeated-k-times) (Hard)
-  1. [Number of Equal Count Substrings](../number-of-equal-count-substrings) (Medium)
diff --git a/problems/longest-substring-with-at-least-k-repeating-characters/longest_substring_with_at_least_k_repeating_characters.go b/problems/longest-substring-with-at-least-k-repeating-characters/longest_substring_with_at_least_k_repeating_characters.go
deleted file mode 100644
index 3aa4ce413..000000000
--- a/problems/longest-substring-with-at-least-k-repeating-characters/longest_substring_with_at_least_k_repeating_characters.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem395
diff --git a/problems/longest-substring-with-at-least-k-repeating-characters/longest_substring_with_at_least_k_repeating_characters_test.go b/problems/longest-substring-with-at-least-k-repeating-characters/longest_substring_with_at_least_k_repeating_characters_test.go
deleted file mode 100644
index 3aa4ce413..000000000
--- a/problems/longest-substring-with-at-least-k-repeating-characters/longest_substring_with_at_least_k_repeating_characters_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem395
diff --git a/problems/longest-substring-with-at-most-k-distinct-characters/README.md b/problems/longest-substring-with-at-most-k-distinct-characters/README.md
deleted file mode 100644
index b2e57c3fa..000000000
--- a/problems/longest-substring-with-at-most-k-distinct-characters/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../nested-list-weight-sum "Nested List Weight Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../flatten-nested-list-iterator "Flatten Nested List Iterator")
-
-## [340. Longest Substring with At Most K Distinct Characters (Medium)](https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters "至多包含 K 个不同字符的最长子串")
-
-<p>Given a string, find the length of the longest substring T that contains at most <i>k</i> distinct characters.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<div>
-<pre>
-<strong>Input: </strong>s = <span id="example-input-1-1">&quot;eceba&quot;</span>, k = <span id="example-input-1-2">2</span>
-<strong>Output: </strong><span id="example-output-1">3</span>
-<strong>Explanation: </strong>T is &quot;ece&quot; which its length is 3.</pre>
-
-<div>
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>s = <span id="example-input-2-1">&quot;aa&quot;</span>, k = <span id="example-input-2-2">1</span>
-<strong>Output: </strong>2
-<strong>Explanation: </strong>T is &quot;aa&quot; which its length is 2.
-</pre>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Longest Substring Without Repeating Characters](../longest-substring-without-repeating-characters) (Medium)
-  1. [Longest Substring with At Most Two Distinct Characters](../longest-substring-with-at-most-two-distinct-characters) (Medium)
-  1. [Longest Repeating Character Replacement](../longest-repeating-character-replacement) (Medium)
-  1. [Subarrays with K Different Integers](../subarrays-with-k-different-integers) (Hard)
-  1. [Max Consecutive Ones III](../max-consecutive-ones-iii) (Medium)
diff --git a/problems/longest-substring-with-at-most-k-distinct-characters/longest_substring_with_at_most_k_distinct_characters.go b/problems/longest-substring-with-at-most-k-distinct-characters/longest_substring_with_at_most_k_distinct_characters.go
deleted file mode 100644
index a5790d8d8..000000000
--- a/problems/longest-substring-with-at-most-k-distinct-characters/longest_substring_with_at_most_k_distinct_characters.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem340
diff --git a/problems/longest-substring-with-at-most-k-distinct-characters/longest_substring_with_at_most_k_distinct_characters_test.go b/problems/longest-substring-with-at-most-k-distinct-characters/longest_substring_with_at_most_k_distinct_characters_test.go
deleted file mode 100644
index a5790d8d8..000000000
--- a/problems/longest-substring-with-at-most-k-distinct-characters/longest_substring_with_at_most_k_distinct_characters_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem340
diff --git a/problems/longest-substring-with-at-most-two-distinct-characters/README.md b/problems/longest-substring-with-at-most-two-distinct-characters/README.md
deleted file mode 100644
index 34675cf52..000000000
--- a/problems/longest-substring-with-at-most-two-distinct-characters/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../read-n-characters-given-read4-ii-call-multiple-times "Read N Characters Given read4 II - Call Multiple Times")
-　　　　　　　　　　　　　　　　
-[Next >](../intersection-of-two-linked-lists "Intersection of Two Linked Lists")
-
-## [159. Longest Substring with At Most Two Distinct Characters (Medium)](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters "至多包含两个不同字符的最长子串")
-
-<p>Given a string <strong><em>s</em></strong> , find the length of the longest substring&nbsp;<strong><em>t&nbsp;&nbsp;</em></strong>that contains <strong>at most </strong>2 distinct characters.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre><strong>Input:</strong> &quot;eceba&quot;
-<strong>Output: </strong>3
-<strong>Explanation: <em>t</em></strong><em> </em>is &quot;ece&quot; which its length is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre><strong>Input:</strong> &quot;ccaabbb&quot;
-<strong>Output: </strong>5
-<strong>Explanation: <em>t</em></strong><em> </em>is &quot;aabbb&quot; which its length is 5.
-</pre>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Longest Substring Without Repeating Characters](../longest-substring-without-repeating-characters) (Medium)
-  1. [Sliding Window Maximum](../sliding-window-maximum) (Hard)
-  1. [Longest Substring with At Most K Distinct Characters](../longest-substring-with-at-most-k-distinct-characters) (Medium)
-  1. [Subarrays with K Different Integers](../subarrays-with-k-different-integers) (Hard)
diff --git a/problems/longest-substring-with-at-most-two-distinct-characters/longest_substring_with_at_most_two_distinct_characters.go b/problems/longest-substring-with-at-most-two-distinct-characters/longest_substring_with_at_most_two_distinct_characters.go
deleted file mode 100644
index efc10f9cd..000000000
--- a/problems/longest-substring-with-at-most-two-distinct-characters/longest_substring_with_at_most_two_distinct_characters.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem159
diff --git a/problems/longest-substring-with-at-most-two-distinct-characters/longest_substring_with_at_most_two_distinct_characters_test.go b/problems/longest-substring-with-at-most-two-distinct-characters/longest_substring_with_at_most_two_distinct_characters_test.go
deleted file mode 100644
index efc10f9cd..000000000
--- a/problems/longest-substring-with-at-most-two-distinct-characters/longest_substring_with_at_most_two_distinct_characters_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem159
diff --git a/problems/longest-substring-without-repeating-characters/README.md b/problems/longest-substring-without-repeating-characters/README.md
deleted file mode 100644
index a1ce2b5d4..000000000
--- a/problems/longest-substring-without-repeating-characters/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-two-numbers "Add Two Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../median-of-two-sorted-arrays "Median of Two Sorted Arrays")
-
-## [3. Longest Substring Without Repeating Characters (Medium)](https://leetcode.com/problems/longest-substring-without-repeating-characters "无重复字符的最长子串")
-
-<p>Given a string <code>s</code>, find the length of the <b>longest substring</b> without repeating characters.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcabcbb&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The answer is &quot;abc&quot;, with the length of 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bbbbb&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The answer is &quot;b&quot;, with the length of 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;pwwkew&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The answer is &quot;wke&quot;, with the length of 3.
-Notice that the answer must be a substring, &quot;pwke&quot; is a subsequence and not a substring.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;&quot;
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of English letters, digits, symbols and spaces.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Longest Substring with At Most Two Distinct Characters](../longest-substring-with-at-most-two-distinct-characters) (Medium)
-  1. [Longest Substring with At Most K Distinct Characters](../longest-substring-with-at-most-k-distinct-characters) (Medium)
-  1. [Subarrays with K Different Integers](../subarrays-with-k-different-integers) (Hard)
diff --git a/problems/longest-substring-without-repeating-characters/longest_substring_without_repeating_characters.go b/problems/longest-substring-without-repeating-characters/longest_substring_without_repeating_characters.go
deleted file mode 100644
index 2dcdcb6d8..000000000
--- a/problems/longest-substring-without-repeating-characters/longest_substring_without_repeating_characters.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem3
-
-func lengthOfLongestSubstring(s string) int {
-	ans, l := 0, len(s)
-	index := [128]int{}
-	for i, j := 0, 0; j < l; j++ {
-		if i < index[s[j]] {
-			i = index[s[j]]
-		}
-		if ans < j-i+1 {
-			ans = j - i + 1
-		}
-		index[s[j]] = j + 1
-	}
-	return ans
-}
diff --git a/problems/longest-substring-without-repeating-characters/longest_substring_without_repeating_characters_test.go b/problems/longest-substring-without-repeating-characters/longest_substring_without_repeating_characters_test.go
deleted file mode 100644
index d1048a179..000000000
--- a/problems/longest-substring-without-repeating-characters/longest_substring_without_repeating_characters_test.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem3
-
-import "testing"
-
-func TestLengthOfLongestSubstring(t *testing.T) {
-	tests := map[string]int{
-		"abcabcbb": 3,
-		"bbbbb":    1,
-		"pwwkew":   3,
-		"abcdef":   6,
-	}
-
-	for in, want := range tests {
-		got := lengthOfLongestSubstring(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/longest-turbulent-subarray/README.md b/problems/longest-turbulent-subarray/README.md
deleted file mode 100644
index f73561019..000000000
--- a/problems/longest-turbulent-subarray/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../squares-of-a-sorted-array "Squares of a Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../distribute-coins-in-binary-tree "Distribute Coins in Binary Tree")
-
-## [978. Longest Turbulent Subarray (Medium)](https://leetcode.com/problems/longest-turbulent-subarray "最长湍流子数组")
-
-<p>Given an integer array <code>arr</code>, return <em>the length of a maximum size turbulent subarray of</em> <code>arr</code>.</p>
-
-<p>A subarray is <strong>turbulent</strong> if the comparison sign flips between each adjacent pair of elements in the subarray.</p>
-
-<p>More formally, a subarray <code>[arr[i], arr[i + 1], ..., arr[j]]</code> of <code>arr</code> is said to be turbulent if and only if:</p>
-
-<ul>
-	<li>For <code>i &lt;= k &lt; j</code>:
-	<ul>
-		<li><code>arr[k] &gt; arr[k + 1]</code> when <code>k</code> is odd, and</li>
-		<li><code>arr[k] &lt; arr[k + 1]</code> when <code>k</code> is even.</li>
-	</ul>
-	</li>
-	<li>Or, for <code>i &lt;= k &lt; j</code>:
-	<ul>
-		<li><code>arr[k] &gt; arr[k + 1]</code> when <code>k</code> is even, and</li>
-		<li><code>arr[k] &lt; arr[k + 1]</code> when <code>k</code> is odd.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [9,4,2,10,7,8,8,1,9]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> arr[1] &gt; arr[2] &lt; arr[3] &gt; arr[4] &lt; arr[5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,8,12,16]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [100]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 4 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Maximum Subarray](../maximum-subarray) (Easy)
diff --git a/problems/longest-turbulent-subarray/longest_turbulent_subarray.go b/problems/longest-turbulent-subarray/longest_turbulent_subarray.go
deleted file mode 100644
index 29b5404ee..000000000
--- a/problems/longest-turbulent-subarray/longest_turbulent_subarray.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem978
diff --git a/problems/longest-uncommon-subsequence-i/README.md b/problems/longest-uncommon-subsequence-i/README.md
deleted file mode 100644
index eaafad4e9..000000000
--- a/problems/longest-uncommon-subsequence-i/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../detect-capital "Detect Capital")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-uncommon-subsequence-ii "Longest Uncommon Subsequence II")
-
-## [521. Longest Uncommon Subsequence I (Easy)](https://leetcode.com/problems/longest-uncommon-subsequence-i "最长特殊序列 Ⅰ")
-
-<p>Given two strings <code>a</code> and <code>b</code>, return <em>the length of the <strong>longest uncommon subsequence</strong> between </em><code>a</code> <em>and</em> <code>b</code>. If the longest uncommon subsequence does not exist, return <code>-1</code>.</p>
-
-<p>An <strong>uncommon subsequence</strong> between two strings is a string that is a <strong>subsequence of one but not the other</strong>.</p>
-
-<p>A <strong>subsequence</strong> of a string <code>s</code> is a string that can be obtained after deleting any number of characters from <code>s</code>.</p>
-
-<ul>
-	<li>For example, <code>&quot;abc&quot;</code> is a subsequence of <code>&quot;aebdc&quot;</code> because you can delete the underlined characters in <code>&quot;a<u>e</u>b<u>d</u>c&quot;</code> to get <code>&quot;abc&quot;</code>. Other subsequences of <code>&quot;aebdc&quot;</code> include <code>&quot;aebdc&quot;</code>, <code>&quot;aeb&quot;</code>, and <code>&quot;&quot;</code> (empty string).</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;aba&quot;, b = &quot;cdc&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> One longest uncommon subsequence is &quot;aba&quot; because &quot;aba&quot; is a subsequence of &quot;aba&quot; but not &quot;cdc&quot;.
-Note that &quot;cdc&quot; is also a longest uncommon subsequence.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;aaa&quot;, b = &quot;bbb&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>&nbsp;The longest uncommon subsequences are &quot;aaa&quot; and &quot;bbb&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;aaa&quot;, b = &quot;aaa&quot;
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>&nbsp;Every subsequence of string a is also a subsequence of string b. Similarly, every subsequence of string b is also a subsequence of string a.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= a.length, b.length &lt;= 100</code></li>
-	<li><code>a</code> and <code>b</code> consist of lower-case English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Longest Uncommon Subsequence II](../longest-uncommon-subsequence-ii) (Medium)
diff --git a/problems/longest-uncommon-subsequence-i/longest_uncommon_subsequence_i.go b/problems/longest-uncommon-subsequence-i/longest_uncommon_subsequence_i.go
deleted file mode 100644
index 900490eb3..000000000
--- a/problems/longest-uncommon-subsequence-i/longest_uncommon_subsequence_i.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package problem521
-
-func findLUSlength(a string, b string) int {
-	if a == b {
-		return -1
-	}
-	if len(a) > len(b) {
-		return len(a)
-	}
-	return len(b)
-}
diff --git a/problems/longest-uncommon-subsequence-i/longest_uncommon_subsequence_i_test.go b/problems/longest-uncommon-subsequence-i/longest_uncommon_subsequence_i_test.go
deleted file mode 100644
index 2836f24df..000000000
--- a/problems/longest-uncommon-subsequence-i/longest_uncommon_subsequence_i_test.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package problem521
-
-import "testing"
-
-type testType struct {
-	a    string
-	b    string
-	want int
-}
-
-func TestFindLUSlength(t *testing.T) {
-	tests := [...]testType{
-		{
-			a:    "aba",
-			b:    "cdc",
-			want: 3,
-		},
-		{
-			a:    "aba",
-			b:    "abcdef",
-			want: 6,
-		},
-		{
-			a:    "abcdef",
-			b:    "cdc",
-			want: 6,
-		},
-		{
-			a:    "abc",
-			b:    "abc",
-			want: -1,
-		},
-	}
-	for _, tt := range tests {
-		got := findLUSlength(tt.a, tt.b)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.a, tt.b, got, tt.want)
-		}
-	}
-}
diff --git a/problems/longest-uncommon-subsequence-ii/README.md b/problems/longest-uncommon-subsequence-ii/README.md
deleted file mode 100644
index be9dd896a..000000000
--- a/problems/longest-uncommon-subsequence-ii/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-uncommon-subsequence-i "Longest Uncommon Subsequence I")
-　　　　　　　　　　　　　　　　
-[Next >](../continuous-subarray-sum "Continuous Subarray Sum")
-
-## [522. Longest Uncommon Subsequence II (Medium)](https://leetcode.com/problems/longest-uncommon-subsequence-ii "最长特殊序列 II")
-
-<p>Given an array of strings <code>strs</code>, return <em>the length of the <strong>longest uncommon subsequence</strong> between them</em>. If the longest uncommon subsequence does not exist, return <code>-1</code>.</p>
-
-<p>An <strong>uncommon subsequence</strong> between an array of strings is a string that is a <strong>subsequence of one string but not the others</strong>.</p>
-
-<p>A <strong>subsequence</strong> of a string <code>s</code> is a string that can be obtained after deleting any number of characters from <code>s</code>.</p>
-
-<ul>
-	<li>For example, <code>&quot;abc&quot;</code> is a subsequence of <code>&quot;aebdc&quot;</code> because you can delete the underlined characters in <code>&quot;a<u>e</u>b<u>d</u>c&quot;</code> to get <code>&quot;abc&quot;</code>. Other subsequences of <code>&quot;aebdc&quot;</code> include <code>&quot;aebdc&quot;</code>, <code>&quot;aeb&quot;</code>, and <code>&quot;&quot;</code> (empty string).</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> strs = ["aba","cdc","eae"]
-<strong>Output:</strong> 3
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> strs = ["aaa","aaa","aa"]
-<strong>Output:</strong> -1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= strs.length &lt;= 50</code></li>
-	<li><code>1 &lt;= strs[i].length &lt;= 10</code></li>
-	<li><code>strs[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Longest Uncommon Subsequence I](../longest-uncommon-subsequence-i) (Easy)
diff --git a/problems/longest-uncommon-subsequence-ii/longest_uncommon_subsequence_ii.go b/problems/longest-uncommon-subsequence-ii/longest_uncommon_subsequence_ii.go
deleted file mode 100644
index 3560e47f2..000000000
--- a/problems/longest-uncommon-subsequence-ii/longest_uncommon_subsequence_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem522
diff --git a/problems/longest-uncommon-subsequence-ii/longest_uncommon_subsequence_ii_test.go b/problems/longest-uncommon-subsequence-ii/longest_uncommon_subsequence_ii_test.go
deleted file mode 100644
index 3560e47f2..000000000
--- a/problems/longest-uncommon-subsequence-ii/longest_uncommon_subsequence_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem522
diff --git a/problems/longest-univalue-path/README.md b/problems/longest-univalue-path/README.md
deleted file mode 100644
index 87333d2cc..000000000
--- a/problems/longest-univalue-path/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../repeated-string-match "Repeated String Match")
-　　　　　　　　　　　　　　　　
-[Next >](../knight-probability-in-chessboard "Knight Probability in Chessboard")
-
-## [687. Longest Univalue Path (Medium)](https://leetcode.com/problems/longest-univalue-path "最长同值路径")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the length of the longest path, where each node in the path has the same value</em>. This path may or may not pass through the root.</p>
-
-<p><strong>The length of the path</strong> between two nodes is represented by the number of edges between them.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/13/ex1.jpg" style="width: 571px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [5,4,5,1,1,5]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/13/ex2.jpg" style="width: 571px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [1,4,5,4,4,5]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-	<li>The depth of the tree will not exceed <code>1000</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Maximum Path Sum](../binary-tree-maximum-path-sum) (Hard)
-  1. [Count Univalue Subtrees](../count-univalue-subtrees) (Medium)
-  1. [Path Sum III](../path-sum-iii) (Medium)
diff --git a/problems/longest-univalue-path/longest_univalue_path.go b/problems/longest-univalue-path/longest_univalue_path.go
deleted file mode 100644
index 9e5d5ccab..000000000
--- a/problems/longest-univalue-path/longest_univalue_path.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem687
diff --git a/problems/longest-univalue-path/longest_univalue_path_test.go b/problems/longest-univalue-path/longest_univalue_path_test.go
deleted file mode 100644
index 9e5d5ccab..000000000
--- a/problems/longest-univalue-path/longest_univalue_path_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem687
diff --git a/problems/longest-valid-parentheses/README.md b/problems/longest-valid-parentheses/README.md
deleted file mode 100644
index b4b9e1f9f..000000000
--- a/problems/longest-valid-parentheses/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../next-permutation "Next Permutation")
-　　　　　　　　　　　　　　　　
-[Next >](../search-in-rotated-sorted-array "Search in Rotated Sorted Array")
-
-## [32. Longest Valid Parentheses (Hard)](https://leetcode.com/problems/longest-valid-parentheses "最长有效括号")
-
-<p>Given a string containing just the characters <code>&#39;(&#39;</code> and <code>&#39;)&#39;</code>, find the length of the longest valid (well-formed) parentheses substring.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(()&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The longest valid parentheses substring is &quot;()&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;)()())&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The longest valid parentheses substring is &quot;()()&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;&quot;
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>s[i]</code> is <code>&#39;(&#39;</code>, or <code>&#39;)&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Valid Parentheses](../valid-parentheses) (Easy)
diff --git a/problems/longest-valid-parentheses/longest_valid_parentheses.go b/problems/longest-valid-parentheses/longest_valid_parentheses.go
deleted file mode 100644
index 138fca601..000000000
--- a/problems/longest-valid-parentheses/longest_valid_parentheses.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package problem32
-
-func longestValidParentheses(s string) int {
-	ans, l := 0, len(s)
-	dp := make([]int, l)
-	for i, c := range s {
-		if i == 0 || c == '(' {
-			continue
-		}
-		if s[i-1] == '(' {
-			dp[i] = 2
-			if i > 1 {
-				dp[i] += dp[i-2]
-			}
-		} else if i > dp[i-1] && s[i-1-dp[i-1]] == '(' {
-			dp[i] = dp[i-1] + 2
-			if i-1 > dp[i-1] {
-				dp[i] += dp[i-2-dp[i-1]]
-			}
-		}
-		if dp[i] > ans {
-			ans = dp[i]
-		}
-	}
-	return ans
-}
diff --git a/problems/longest-valid-parentheses/longest_valid_parentheses_test.go b/problems/longest-valid-parentheses/longest_valid_parentheses_test.go
deleted file mode 100644
index d77b2d465..000000000
--- a/problems/longest-valid-parentheses/longest_valid_parentheses_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem32
-
-import "testing"
-
-type testType struct {
-	in   string
-	want int
-}
-
-func TestLongestValidParentheses(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "(()",
-			want: 2,
-		},
-		{
-			in:   ")()())",
-			want: 4,
-		},
-		{
-			in:   ")()())(())()(",
-			want: 6,
-		},
-		{
-			in:   "()(())",
-			want: 6,
-		},
-	}
-	for _, tt := range tests {
-		got := longestValidParentheses(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/longest-well-performing-interval/README.md b/problems/longest-well-performing-interval/README.md
deleted file mode 100644
index d9318ddc4..000000000
--- a/problems/longest-well-performing-interval/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lowest-common-ancestor-of-deepest-leaves "Lowest Common Ancestor of Deepest Leaves")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-sufficient-team "Smallest Sufficient Team")
-
-## [1124. Longest Well-Performing Interval (Medium)](https://leetcode.com/problems/longest-well-performing-interval "表现良好的最长时间段")
-
-<p>We are given <code>hours</code>, a list of the number of hours worked per day for a given employee.</p>
-
-<p>A day is considered to be a <em>tiring day</em> if and only if the number of hours worked is (strictly) greater than <code>8</code>.</p>
-
-<p>A <em>well-performing interval</em> is an interval of days for which the number of tiring days is strictly larger than the number of non-tiring days.</p>
-
-<p>Return the length of the longest well-performing interval.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> hours = [9,9,6,0,6,6,9]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>The longest well-performing interval is [9,9,6].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> hours = [6,6,6]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= hours.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= hours[i] &lt;= 16</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Make a new array A of +1/-1s corresponding to if hours[i] is > 8 or not. The goal is to find the longest subarray with positive sum.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Using prefix sums (PrefixSum[i+1] = A[0] + A[1] + ... + A[i]), you need to find for each j, the smallest i < j with PrefixSum[i] + 1 == PrefixSum[j].
-</details>
diff --git a/problems/longest-well-performing-interval/longest_well_performing_interval.go b/problems/longest-well-performing-interval/longest_well_performing_interval.go
deleted file mode 100644
index 80ccb2806..000000000
--- a/problems/longest-well-performing-interval/longest_well_performing_interval.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1124
diff --git a/problems/longest-winning-streak/README.md b/problems/longest-winning-streak/README.md
deleted file mode 100644
index d136c15df..000000000
--- a/problems/longest-winning-streak/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-and-sum-of-array "Maximum AND Sum of Array")
-　　　　　　　　　　　　　　　　
-Next >
-
-## [2173. Longest Winning Streak (Hard)](https://leetcode.com/problems/longest-winning-streak "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/longest-winning-streak/mysql_schemas.sql b/problems/longest-winning-streak/mysql_schemas.sql
deleted file mode 100644
index 6da5cb0fb..000000000
--- a/problems/longest-winning-streak/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Matches (player_id int, match_day date, result ENUM('Win', 'Draw', 'Lose'));
-Truncate table Matches;
-insert into Matches (player_id, match_day, result) values ('1', '2022-01-17', 'Win');
-insert into Matches (player_id, match_day, result) values ('1', '2022-01-18', 'Win');
-insert into Matches (player_id, match_day, result) values ('1', '2022-01-25', 'Win');
-insert into Matches (player_id, match_day, result) values ('1', '2022-01-31', 'Draw');
-insert into Matches (player_id, match_day, result) values ('1', '2022-02-08', 'Win');
-insert into Matches (player_id, match_day, result) values ('2', '2022-02-06', 'Lose');
-insert into Matches (player_id, match_day, result) values ('2', '2022-02-08', 'Lose');
-insert into Matches (player_id, match_day, result) values ('3', '2022-03-30', 'Win');
diff --git a/problems/longest-word-in-dictionary-through-deleting/README.md b/problems/longest-word-in-dictionary-through-deleting/README.md
deleted file mode 100644
index 4569d4553..000000000
--- a/problems/longest-word-in-dictionary-through-deleting/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../continuous-subarray-sum "Continuous Subarray Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../contiguous-array "Contiguous Array")
-
-## [524. Longest Word in Dictionary through Deleting (Medium)](https://leetcode.com/problems/longest-word-in-dictionary-through-deleting "通过删除字母匹配到字典里最长单词")
-
-<p>Given a string <code>s</code> and a string array <code>dictionary</code>, return <em>the longest string in the dictionary that can be formed by deleting some of the given string characters</em>. If there is more than one possible result, return the longest word with the smallest lexicographical order. If there is no possible result, return the empty string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abpcplea&quot;, dictionary = [&quot;ale&quot;,&quot;apple&quot;,&quot;monkey&quot;,&quot;plea&quot;]
-<strong>Output:</strong> &quot;apple&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abpcplea&quot;, dictionary = [&quot;a&quot;,&quot;b&quot;,&quot;c&quot;]
-<strong>Output:</strong> &quot;a&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= dictionary.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= dictionary[i].length &lt;= 1000</code></li>
-	<li><code>s</code> and <code>dictionary[i]</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Longest Word in Dictionary](../longest-word-in-dictionary) (Medium)
diff --git a/problems/longest-word-in-dictionary-through-deleting/longest_word_in_dictionary_through_deleting.go b/problems/longest-word-in-dictionary-through-deleting/longest_word_in_dictionary_through_deleting.go
deleted file mode 100644
index c6d8f8d66..000000000
--- a/problems/longest-word-in-dictionary-through-deleting/longest_word_in_dictionary_through_deleting.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem524
diff --git a/problems/longest-word-in-dictionary-through-deleting/longest_word_in_dictionary_through_deleting_test.go b/problems/longest-word-in-dictionary-through-deleting/longest_word_in_dictionary_through_deleting_test.go
deleted file mode 100644
index c6d8f8d66..000000000
--- a/problems/longest-word-in-dictionary-through-deleting/longest_word_in_dictionary_through_deleting_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem524
diff --git a/problems/longest-word-in-dictionary/README.md b/problems/longest-word-in-dictionary/README.md
deleted file mode 100644
index 4af3ff4db..000000000
--- a/problems/longest-word-in-dictionary/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-k-th-smallest-pair-distance "Find K-th Smallest Pair Distance")
-　　　　　　　　　　　　　　　　
-[Next >](../accounts-merge "Accounts Merge")
-
-## [720. Longest Word in Dictionary (Easy)](https://leetcode.com/problems/longest-word-in-dictionary "词典中最长的单词")
-
-<p>Given an array of strings <code>words</code> representing an English Dictionary, return <em>the longest word in</em> <code>words</code> <em>that can be built one character at a time by other words in</em> <code>words</code>.</p>
-
-<p>If there is more than one possible answer, return the longest word with the smallest lexicographical order. If there is no answer, return the empty string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;w&quot;,&quot;wo&quot;,&quot;wor&quot;,&quot;worl&quot;,&quot;world&quot;]
-<strong>Output:</strong> &quot;world&quot;
-<strong>Explanation:</strong> The word &quot;world&quot; can be built one character at a time by &quot;w&quot;, &quot;wo&quot;, &quot;wor&quot;, and &quot;worl&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;a&quot;,&quot;banana&quot;,&quot;app&quot;,&quot;appl&quot;,&quot;ap&quot;,&quot;apply&quot;,&quot;apple&quot;]
-<strong>Output:</strong> &quot;apple&quot;
-<strong>Explanation:</strong> Both &quot;apply&quot; and &quot;apple&quot; can be built from other words in the dictionary. However, &quot;apple&quot; is lexicographically smaller than &quot;apply&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 30</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Longest Word in Dictionary through Deleting](../longest-word-in-dictionary-through-deleting) (Medium)
-  1. [Implement Magic Dictionary](../implement-magic-dictionary) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For every word in the input list, we can check whether all prefixes of that word are in the input list by using a Set.
-</details>
diff --git a/problems/longest-word-in-dictionary/longest_word_in_dictionary.go b/problems/longest-word-in-dictionary/longest_word_in_dictionary.go
deleted file mode 100644
index 62df4f52a..000000000
--- a/problems/longest-word-in-dictionary/longest_word_in_dictionary.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem720
diff --git a/problems/longest-word-in-dictionary/longest_word_in_dictionary_test.go b/problems/longest-word-in-dictionary/longest_word_in_dictionary_test.go
deleted file mode 100644
index 62df4f52a..000000000
--- a/problems/longest-word-in-dictionary/longest_word_in_dictionary_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem720
diff --git a/problems/longest-word-with-all-prefixes/README.md b/problems/longest-word-with-all-prefixes/README.md
deleted file mode 100644
index f43785bbb..000000000
--- a/problems/longest-word-with-all-prefixes/README.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-color-value-in-a-directed-graph "Largest Color Value in a Directed Graph")
-　　　　　　　　　　　　　　　　
-[Next >](../sorting-the-sentence "Sorting the Sentence")
-
-## [1858. Longest Word With All Prefixes (Medium)](https://leetcode.com/problems/longest-word-with-all-prefixes "包含所有前缀的最长单词")
-
-
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Add all the words to a trie.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check the longest path where all the nodes are words.
-</details>
diff --git a/problems/longest-zigzag-path-in-a-binary-tree/README.md b/problems/longest-zigzag-path-in-a-binary-tree/README.md
deleted file mode 100644
index 9790e1013..000000000
--- a/problems/longest-zigzag-path-in-a-binary-tree/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-longest-substring-containing-vowels-in-even-counts "Find the Longest Substring Containing Vowels in Even Counts")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-sum-bst-in-binary-tree "Maximum Sum BST in Binary Tree")
-
-## [1372. Longest ZigZag Path in a Binary Tree (Medium)](https://leetcode.com/problems/longest-zigzag-path-in-a-binary-tree "二叉树中的最长交错路径")
-
-<p>You are given the <code>root</code> of a binary tree.</p>
-
-<p>A ZigZag path for a binary tree is defined as follow:</p>
-
-<ul>
-	<li>Choose <strong>any </strong>node in the binary tree and a direction (right or left).</li>
-	<li>If the current direction is right, move to the right child of the current node; otherwise, move to the left child.</li>
-	<li>Change the direction from right to left or from left to right.</li>
-	<li>Repeat the second and third steps until you can&#39;t move in the tree.</li>
-</ul>
-
-<p>Zigzag length is defined as the number of nodes visited - 1. (A single node has a length of 0).</p>
-
-<p>Return <em>the longest <strong>ZigZag</strong> path contained in that tree</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/22/sample_1_1702.png" style="width: 221px; height: 383px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,1,1,1,null,null,1,1,null,1,null,null,null,1,null,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Longest ZigZag path in blue nodes (right -&gt; left -&gt; right).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/22/sample_2_1702.png" style="width: 157px; height: 329px;" />
-<pre>
-<strong>Input:</strong> root = [1,1,1,null,1,null,null,1,1,null,1]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Longest ZigZag path in blue nodes (left -&gt; right -&gt; left -&gt; right).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 5 * 10<sup>4</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create this function maxZigZag(node, direction) maximum zigzag given a node and direction (right or left).
-</details>
diff --git a/problems/loud-and-rich/README.md b/problems/loud-and-rich/README.md
deleted file mode 100644
index 051aa61ab..000000000
--- a/problems/loud-and-rich/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rectangle-area-ii "Rectangle Area II")
-　　　　　　　　　　　　　　　　
-[Next >](../peak-index-in-a-mountain-array "Peak Index in a Mountain Array")
-
-## [851. Loud and Rich (Medium)](https://leetcode.com/problems/loud-and-rich "喧闹和富有")
-
-<p>There is a group of <code>n</code> people labeled from <code>0</code> to <code>n - 1</code> where each person has a different amount of money and a different level of quietness.</p>
-
-<p>You are given an array <code>richer</code> where <code>richer[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that <code>a<sub>i</sub></code> has more money than <code>b<sub>i</sub></code> and an integer array <code>quiet</code> where <code>quiet[i]</code> is the quietness of the <code>i<sup>th</sup></code> person. All the given data in richer are <strong>logically correct</strong> (i.e., the data will not lead you to a situation where <code>x</code> is richer than <code>y</code> and <code>y</code> is richer than <code>x</code> at the same time).</p>
-
-<p>Return <em>an integer array </em><code>answer</code><em> where </em><code>answer[x] = y</code><em> if </em><code>y</code><em> is the least quiet person (that is, the person </em><code>y</code><em> with the smallest value of </em><code>quiet[y]</code><em>) among all people who definitely have equal to or more money than the person </em><code>x</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> richer = [[1,0],[2,1],[3,1],[3,7],[4,3],[5,3],[6,3]], quiet = [3,2,5,4,6,1,7,0]
-<strong>Output:</strong> [5,5,2,5,4,5,6,7]
-<strong>Explanation:</strong> 
-answer[0] = 5.
-Person 5 has more money than 3, which has more money than 1, which has more money than 0.
-The only person who is quieter (has lower quiet[x]) is person 7, but it is not clear if they have more money than person 0.
-answer[7] = 7.
-Among all people that definitely have equal to or more money than person 7 (which could be persons 3, 4, 5, 6, or 7), the person who is the quietest (has lower quiet[x]) is person 7.
-The other answers can be filled out with similar reasoning.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> richer = [], quiet = [0]
-<strong>Output:</strong> [0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == quiet.length</code></li>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-	<li><code>0 &lt;= quiet[i] &lt; n</code></li>
-	<li>All the values of <code>quiet</code> are <strong>unique</strong>.</li>
-	<li><code>0 &lt;= richer.length &lt;= n * (n - 1) / 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt; n</code></li>
-	<li><code>a<sub>i </sub>!= b<sub>i</sub></code></li>
-	<li>All the pairs of <code>richer</code> are <strong>unique</strong>.</li>
-	<li>The observations in <code>richer</code> are all logically consistent.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Array](../../tag/array/README.md)]
diff --git a/problems/loud-and-rich/loud_and_rich.go b/problems/loud-and-rich/loud_and_rich.go
deleted file mode 100644
index f724c8ef0..000000000
--- a/problems/loud-and-rich/loud_and_rich.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem851
diff --git a/problems/loud-and-rich/loud_and_rich_test.go b/problems/loud-and-rich/loud_and_rich_test.go
deleted file mode 100644
index f724c8ef0..000000000
--- a/problems/loud-and-rich/loud_and_rich_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem851
diff --git a/problems/low-quality-problems/README.md b/problems/low-quality-problems/README.md
deleted file mode 100644
index 09b5a0c7a..000000000
--- a/problems/low-quality-problems/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-ways-to-partition-an-array "Maximum Number of Ways to Partition an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-moves-to-convert-string "Minimum Moves to Convert String")
-
-## [2026. Low-Quality Problems (Easy)](https://leetcode.com/problems/low-quality-problems "低质量的问题")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/low-quality-problems/mysql_schemas.sql b/problems/low-quality-problems/mysql_schemas.sql
deleted file mode 100644
index 07951b77f..000000000
--- a/problems/low-quality-problems/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Problems (problem_id int, likes int, dislikes int);
-Truncate table Problems;
-insert into Problems (problem_id, likes, dislikes) values ('6', '1290', '425');
-insert into Problems (problem_id, likes, dislikes) values ('11', '2677', '8659');
-insert into Problems (problem_id, likes, dislikes) values ('1', '4446', '2760');
-insert into Problems (problem_id, likes, dislikes) values ('7', '8569', '6086');
-insert into Problems (problem_id, likes, dislikes) values ('13', '2050', '4164');
-insert into Problems (problem_id, likes, dislikes) values ('10', '9002', '7446');
diff --git a/problems/lowest-common-ancestor-of-a-binary-search-tree/README.md b/problems/lowest-common-ancestor-of-a-binary-search-tree/README.md
deleted file mode 100644
index ec0abe1e0..000000000
--- a/problems/lowest-common-ancestor-of-a-binary-search-tree/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-linked-list "Palindrome Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../lowest-common-ancestor-of-a-binary-tree "Lowest Common Ancestor of a Binary Tree")
-
-## [235. Lowest Common Ancestor of a Binary Search Tree (Easy)](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree "二叉搜索树的最近公共祖先")
-
-<p>Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.</p>
-
-<p>According to the <a href="https://en.wikipedia.org/wiki/Lowest_common_ancestor" target="_blank">definition of LCA on Wikipedia</a>: &ldquo;The lowest common ancestor is defined between two nodes <code>p</code> and <code>q</code> as the lowest node in <code>T</code> that has both <code>p</code> and <code>q</code> as descendants (where we allow <b>a node to be a descendant of itself</b>).&rdquo;</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/14/binarysearchtree_improved.png" style="width: 200px; height: 190px;" />
-<pre>
-<strong>Input:</strong> root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The LCA of nodes 2 and 8 is 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/14/binarysearchtree_improved.png" style="width: 200px; height: 190px;" />
-<pre>
-<strong>Input:</strong> root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [2,1], p = 2, q = 1
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[2, 10<sup>5</sup>]</code>.</li>
-	<li><code>-10<sup>9</sup> &lt;= Node.val &lt;= 10<sup>9</sup></code></li>
-	<li>All <code>Node.val</code> are <strong>unique</strong>.</li>
-	<li><code>p != q</code></li>
-	<li><code>p</code> and <code>q</code> will exist in the BST.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Lowest Common Ancestor of a Binary Tree](../lowest-common-ancestor-of-a-binary-tree) (Medium)
-  1. [Smallest Common Region](../smallest-common-region) (Medium)
diff --git a/problems/lowest-common-ancestor-of-a-binary-search-tree/lowest_common_ancestor_of_a_binary_search_tree.go b/problems/lowest-common-ancestor-of-a-binary-search-tree/lowest_common_ancestor_of_a_binary_search_tree.go
deleted file mode 100644
index 2f33d7cc8..000000000
--- a/problems/lowest-common-ancestor-of-a-binary-search-tree/lowest_common_ancestor_of_a_binary_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem235
diff --git a/problems/lowest-common-ancestor-of-a-binary-search-tree/lowest_common_ancestor_of_a_binary_search_tree_test.go b/problems/lowest-common-ancestor-of-a-binary-search-tree/lowest_common_ancestor_of_a_binary_search_tree_test.go
deleted file mode 100644
index 2f33d7cc8..000000000
--- a/problems/lowest-common-ancestor-of-a-binary-search-tree/lowest_common_ancestor_of_a_binary_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem235
diff --git a/problems/lowest-common-ancestor-of-a-binary-tree-ii/README.md b/problems/lowest-common-ancestor-of-a-binary-tree-ii/README.md
deleted file mode 100644
index bd6b7bf17..000000000
--- a/problems/lowest-common-ancestor-of-a-binary-tree-ii/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-smallest-instructions "Kth Smallest Instructions")
-　　　　　　　　　　　　　　　　
-[Next >](../hopper-company-queries-ii "Hopper Company Queries II")
-
-## [1644. Lowest Common Ancestor of a Binary Tree II (Medium)](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-ii "二叉树的最近公共祖先 II")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Traverse the graph visiting root, left, root, right, root to make an Euler Path
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Return the node (LCA) that is at the lowest depth between p and q in the Euler Path
-</details>
diff --git a/problems/lowest-common-ancestor-of-a-binary-tree-iii/README.md b/problems/lowest-common-ancestor-of-a-binary-tree-iii/README.md
deleted file mode 100644
index 856c04b3a..000000000
--- a/problems/lowest-common-ancestor-of-a-binary-tree-iii/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../create-sorted-array-through-instructions "Create Sorted Array through Instructions")
-　　　　　　　　　　　　　　　　
-[Next >](../hopper-company-queries-iii "Hopper Company Queries III")
-
-## [1650. Lowest Common Ancestor of a Binary Tree III (Medium)](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-iii "二叉树的最近公共祖先 III")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Store the path from p to the root.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Traverse the path from q to the root, the first common point of the two paths is the LCA.
-</details>
diff --git a/problems/lowest-common-ancestor-of-a-binary-tree-iv/README.md b/problems/lowest-common-ancestor-of-a-binary-tree-iv/README.md
deleted file mode 100644
index a616f79c8..000000000
--- a/problems/lowest-common-ancestor-of-a-binary-tree-iv/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimize-deviation-in-array "Minimize Deviation in Array")
-　　　　　　　　　　　　　　　　
-[Next >](../products-worth-over-invoices "Product's Worth Over Invoices")
-
-## [1676. Lowest Common Ancestor of a Binary Tree IV (Medium)](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-iv "二叉树的最近公共祖先 IV")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Lowest Common Ancestor of a Binary Search Tree](../lowest-common-ancestor-of-a-binary-search-tree) (Easy)
-  1. [Lowest Common Ancestor of a Binary Tree](../lowest-common-ancestor-of-a-binary-tree) (Medium)
-  1. [Lowest Common Ancestor of Deepest Leaves](../lowest-common-ancestor-of-deepest-leaves) (Medium)
-  1. [Lowest Common Ancestor of a Binary Tree II](../lowest-common-ancestor-of-a-binary-tree-ii) (Medium)
-  1. [Lowest Common Ancestor of a Binary Tree III](../lowest-common-ancestor-of-a-binary-tree-iii) (Medium)
-  1. [Lowest Common Ancestor of a Binary Tree IV](../lowest-common-ancestor-of-a-binary-tree-iv) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Starting from the root, traverse the left and the right subtrees, checking if one of the nodes exist there.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If one of the subtrees doesn't contain any given node, the LCA can be the node returned from the other subtree
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If both subtrees contain nodes, the LCA node is the current node.
-</details>
diff --git a/problems/lowest-common-ancestor-of-a-binary-tree/README.md b/problems/lowest-common-ancestor-of-a-binary-tree/README.md
deleted file mode 100644
index bd54f479f..000000000
--- a/problems/lowest-common-ancestor-of-a-binary-tree/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lowest-common-ancestor-of-a-binary-search-tree "Lowest Common Ancestor of a Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-node-in-a-linked-list "Delete Node in a Linked List")
-
-## [236. Lowest Common Ancestor of a Binary Tree (Medium)](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree "二叉树的最近公共祖先")
-
-<p>Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.</p>
-
-<p>According to the <a href="https://en.wikipedia.org/wiki/Lowest_common_ancestor" target="_blank">definition of LCA on Wikipedia</a>: &ldquo;The lowest common ancestor is defined between two nodes <code>p</code> and <code>q</code> as the lowest node in <code>T</code> that has both <code>p</code> and <code>q</code> as descendants (where we allow <b>a node to be a descendant of itself</b>).&rdquo;</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/14/binarytree.png" style="width: 200px; height: 190px;" />
-<pre>
-<strong>Input:</strong> root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 1
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The LCA of nodes 5 and 1 is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/14/binarytree.png" style="width: 200px; height: 190px;" />
-<pre>
-<strong>Input:</strong> root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 4
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The LCA of nodes 5 and 4 is 5, since a node can be a descendant of itself according to the LCA definition.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,2], p = 1, q = 2
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[2, 10<sup>5</sup>]</code>.</li>
-	<li><code>-10<sup>9</sup> &lt;= Node.val &lt;= 10<sup>9</sup></code></li>
-	<li>All <code>Node.val</code> are <strong>unique</strong>.</li>
-	<li><code>p != q</code></li>
-	<li><code>p</code> and <code>q</code> will exist in the tree.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Lowest Common Ancestor of a Binary Search Tree](../lowest-common-ancestor-of-a-binary-search-tree) (Easy)
-  1. [Smallest Common Region](../smallest-common-region) (Medium)
diff --git a/problems/lowest-common-ancestor-of-a-binary-tree/lowest_common_ancestor_of_a_binary_tree.go b/problems/lowest-common-ancestor-of-a-binary-tree/lowest_common_ancestor_of_a_binary_tree.go
deleted file mode 100644
index 3a144a3a7..000000000
--- a/problems/lowest-common-ancestor-of-a-binary-tree/lowest_common_ancestor_of_a_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem236
diff --git a/problems/lowest-common-ancestor-of-a-binary-tree/lowest_common_ancestor_of_a_binary_tree_test.go b/problems/lowest-common-ancestor-of-a-binary-tree/lowest_common_ancestor_of_a_binary_tree_test.go
deleted file mode 100644
index 3a144a3a7..000000000
--- a/problems/lowest-common-ancestor-of-a-binary-tree/lowest_common_ancestor_of_a_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem236
diff --git a/problems/lowest-common-ancestor-of-deepest-leaves/README.md b/problems/lowest-common-ancestor-of-deepest-leaves/README.md
deleted file mode 100644
index bb79771bb..000000000
--- a/problems/lowest-common-ancestor-of-deepest-leaves/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../relative-sort-array "Relative Sort Array")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-well-performing-interval "Longest Well-Performing Interval")
-
-## [1123. Lowest Common Ancestor of Deepest Leaves (Medium)](https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves "最深叶节点的最近公共祖先")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the lowest common ancestor of its deepest leaves</em>.</p>
-
-<p>Recall that:</p>
-
-<ul>
-	<li>The node of a binary tree is a leaf if and only if it has no children</li>
-	<li>The depth of the root of the tree is <code>0</code>. if the depth of a node is <code>d</code>, the depth of each of its children is <code>d + 1</code>.</li>
-	<li>The lowest common ancestor of a set <code>S</code> of nodes, is the node <code>A</code> with the largest depth such that every node in <code>S</code> is in the subtree with root <code>A</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/07/01/sketch1.png" style="width: 600px; height: 510px;" />
-<pre>
-<strong>Input:</strong> root = [3,5,1,6,2,0,8,null,null,7,4]
-<strong>Output:</strong> [2,7,4]
-<strong>Explanation:</strong> We return the node with value 2, colored in yellow in the diagram.
-The nodes coloured in blue are the deepest leaf-nodes of the tree.
-Note that nodes 6, 0, and 8 are also leaf nodes, but the depth of them is 2, but the depth of nodes 7 and 4 is 3.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [1]
-<strong>Explanation:</strong> The root is the deepest node in the tree, and it&#39;s the lca of itself.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [0,1,3,null,2]
-<strong>Output:</strong> [2]
-<strong>Explanation:</strong> The deepest leaf node in the tree is 2, the lca of one node is itself.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree will be in the range <code>[1, 1000]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 1000</code></li>
-	<li>The values of the nodes in the tree are <strong>unique</strong>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 865: <a href="https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/" target="_blank">https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/</a></p>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Lowest Common Ancestor of a Binary Tree IV](../lowest-common-ancestor-of-a-binary-tree-iv) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do a postorder traversal.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Then, if both subtrees contain a deepest leaf, you can mark this node as the answer (so far).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The final node marked will be the correct answer.
-</details>
diff --git a/problems/lowest-common-ancestor-of-deepest-leaves/lowest_common_ancestor_of_deepest_leaves.go b/problems/lowest-common-ancestor-of-deepest-leaves/lowest_common_ancestor_of_deepest_leaves.go
deleted file mode 100644
index e3f5f013d..000000000
--- a/problems/lowest-common-ancestor-of-deepest-leaves/lowest_common_ancestor_of_deepest_leaves.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1123
diff --git a/problems/lru-cache/README.md b/problems/lru-cache/README.md
deleted file mode 100644
index 3a5672fc3..000000000
--- a/problems/lru-cache/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-postorder-traversal "Binary Tree Postorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../insertion-sort-list "Insertion Sort List")
-
-## [146. LRU Cache (Medium)](https://leetcode.com/problems/lru-cache "LRU 缓存机制")
-
-<p>Design a data structure that follows the constraints of a <strong><a href="https://en.wikipedia.org/wiki/Cache_replacement_policies#LRU" target="_blank">Least Recently Used (LRU) cache</a></strong>.</p>
-
-<p>Implement the <code>LRUCache</code> class:</p>
-
-<ul>
-	<li><code>LRUCache(int capacity)</code> Initialize the LRU cache with <strong>positive</strong> size <code>capacity</code>.</li>
-	<li><code>int get(int key)</code> Return the value of the <code>key</code> if the key exists, otherwise return <code>-1</code>.</li>
-	<li><code>void put(int key, int value)</code>&nbsp;Update the value of the <code>key</code> if the <code>key</code> exists. Otherwise, add the <code>key-value</code> pair to the cache. If the number of keys exceeds the <code>capacity</code> from this operation, <strong>evict</strong> the least recently used key.</li>
-</ul>
-
-<p>The functions&nbsp;<code data-stringify-type="code">get</code>&nbsp;and&nbsp;<code data-stringify-type="code">put</code>&nbsp;must each run in <code>O(1)</code> average time complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;LRUCache&quot;, &quot;put&quot;, &quot;put&quot;, &quot;get&quot;, &quot;put&quot;, &quot;get&quot;, &quot;put&quot;, &quot;get&quot;, &quot;get&quot;, &quot;get&quot;]
-[[2], [1, 1], [2, 2], [1], [3, 3], [2], [4, 4], [1], [3], [4]]
-<strong>Output</strong>
-[null, null, null, 1, null, -1, null, -1, 3, 4]
-
-<strong>Explanation</strong>
-LRUCache lRUCache = new LRUCache(2);
-lRUCache.put(1, 1); // cache is {1=1}
-lRUCache.put(2, 2); // cache is {1=1, 2=2}
-lRUCache.get(1);    // return 1
-lRUCache.put(3, 3); // LRU key was 2, evicts key 2, cache is {1=1, 3=3}
-lRUCache.get(2);    // returns -1 (not found)
-lRUCache.put(4, 4); // LRU key was 1, evicts key 1, cache is {4=4, 3=3}
-lRUCache.get(1);    // return -1 (not found)
-lRUCache.get(3);    // return 3
-lRUCache.get(4);    // return 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= capacity &lt;= 3000</code></li>
-	<li><code>0 &lt;= key &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= value &lt;= 10<sup>5</sup></code></li>
-	<li>At most 2<code>&nbsp;* 10<sup>5</sup></code>&nbsp;calls will be made to <code>get</code> and <code>put</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Doubly-Linked List](../../tag/doubly-linked-list/README.md)]
-
-### Similar Questions
-  1. [LFU Cache](../lfu-cache) (Hard)
-  1. [Design In-Memory File System](../design-in-memory-file-system) (Hard)
-  1. [Design Compressed String Iterator](../design-compressed-string-iterator) (Easy)
diff --git a/problems/lru-cache/lru_cache.go b/problems/lru-cache/lru_cache.go
deleted file mode 100644
index 837f672d4..000000000
--- a/problems/lru-cache/lru_cache.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem146
diff --git a/problems/lru-cache/lru_cache_test.go b/problems/lru-cache/lru_cache_test.go
deleted file mode 100644
index 837f672d4..000000000
--- a/problems/lru-cache/lru_cache_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem146
diff --git a/problems/lucky-numbers-in-a-matrix/README.md b/problems/lucky-numbers-in-a-matrix/README.md
deleted file mode 100644
index a48481978..000000000
--- a/problems/lucky-numbers-in-a-matrix/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree "Find a Corresponding Node of a Binary Tree in a Clone of That Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../design-a-stack-with-increment-operation "Design a Stack With Increment Operation")
-
-## [1380. Lucky Numbers in a Matrix (Easy)](https://leetcode.com/problems/lucky-numbers-in-a-matrix "矩阵中的幸运数")
-
-<p>Given an <code>m x n</code> matrix of <strong>distinct </strong>numbers, return <em>all <strong>lucky numbers</strong> in the matrix in <strong>any </strong>order</em>.</p>
-
-<p>A <strong>lucky number</strong> is an element of the matrix such that it is the minimum element in its row and maximum in its column.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[3,7,8],[9,11,13],[15,16,17]]
-<strong>Output:</strong> [15]
-<strong>Explanation:</strong> 15 is the only lucky number since it is the minimum in its row and the maximum in its column
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[1,10,4,2],[9,3,8,7],[15,16,17,12]]
-<strong>Output:</strong> [12]
-<strong>Explanation:</strong> 12 is the only lucky number since it is the minimum in its row and the maximum in its column.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[7,8],[1,2]]
-<strong>Output:</strong> [7]
-<strong>Explanation:</strong> 7 is the only lucky number since it is the minimum in its row and the maximum in its column.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[3,6],[7,1],[5,2],[4,8]]
-<strong>Output:</strong> []
-<strong>Explanation:</strong> There is no lucky number.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>1 &lt;= n, m &lt;= 50</code></li>
-	<li><code>1 &lt;= matrix[i][j] &lt;= 10<sup>5</sup></code>.</li>
-	<li>All elements in the matrix are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find out and save the minimum of each row and maximum of each column in two lists.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Then scan through the whole matrix to identify the elements that satisfy the criteria.
-</details>
diff --git a/problems/magic-squares-in-grid/README.md b/problems/magic-squares-in-grid/README.md
deleted file mode 100644
index 64e497d1a..000000000
--- a/problems/magic-squares-in-grid/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../similar-string-groups "Similar String Groups")
-　　　　　　　　　　　　　　　　
-[Next >](../keys-and-rooms "Keys and Rooms")
-
-## [840. Magic Squares In Grid (Medium)](https://leetcode.com/problems/magic-squares-in-grid "矩阵中的幻方")
-
-<p>A <code>3 x 3</code> magic square is a <code>3 x 3</code> grid filled with distinct numbers <strong>from </strong><code>1</code><strong> to </strong><code>9</code> such that each row, column, and both diagonals all have the same sum.</p>
-
-<p>Given a <code>row x col</code>&nbsp;<code>grid</code>&nbsp;of integers, how many <code>3 x 3</code> &quot;magic square&quot; subgrids are there?&nbsp; (Each subgrid is contiguous).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/11/magic_main.jpg" style="width: 322px; height: 242px;" />
-<pre>
-<strong>Input:</strong> grid = [[4,3,8,4],[9,5,1,9],[2,7,6,2]]
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>
-The following subgrid is a 3 x 3 magic square:
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/11/magic_valid.jpg" style="width: 242px; height: 242px;" />
-while this one is not:
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/11/magic_invalid.jpg" style="width: 242px; height: 242px;" />
-In total, there is only one magic square inside the given grid.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[8]]
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[4,4],[3,3]]
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[4,7,8],[9,5,1],[2,3,6]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>row == grid.length</code></li>
-	<li><code>col == grid[i].length</code></li>
-	<li><code>1 &lt;= row, col &lt;= 10</code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;= 15</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/magic-squares-in-grid/magic_squares_in_grid.go b/problems/magic-squares-in-grid/magic_squares_in_grid.go
deleted file mode 100644
index fc299f786..000000000
--- a/problems/magic-squares-in-grid/magic_squares_in_grid.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem840
-
-func numMagicSquaresInside(grid [][]int) int {
-	ans, r, c := 0, len(grid)-1, len(grid[0])-1
-	for i := 1; i < r; i++ {
-	flag:
-		for j := 1; j < c; j++ {
-			if grid[i][j] == 5 &&
-				grid[i-1][j-1]+grid[i-1][j]+grid[i-1][j+1] == 15 &&
-				grid[i+1][j-1]+grid[i+1][j]+grid[i+1][j+1] == 15 &&
-				grid[i-1][j-1]+grid[i][j-1]+grid[i+1][j-1] == 15 &&
-				grid[i-1][j+1]+grid[i][j+1]+grid[i+1][j+1] == 15 &&
-				grid[i-1][j]+grid[i+1][j] == 10 &&
-				grid[i][j-1]+grid[i][j+1] == 10 &&
-				grid[i-1][j-1]+grid[i+1][j+1] == 10 &&
-				grid[i-1][j+1]+grid[i+1][j-1] == 10 {
-				for m := i - 1; m <= i+1; m++ {
-					for n := j - 1; n <= j+1; n++ {
-						if (m != i && n != j && grid[m][n] == 5) || grid[m][n] < 1 || grid[m][n] > 9 {
-							continue flag
-						}
-					}
-				}
-				ans++
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/magic-squares-in-grid/magic_squares_in_grid_test.go b/problems/magic-squares-in-grid/magic_squares_in_grid_test.go
deleted file mode 100644
index 38c8d222a..000000000
--- a/problems/magic-squares-in-grid/magic_squares_in_grid_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem840
-
-import "testing"
-
-type testType struct {
-	in   [][]int
-	want int
-}
-
-func TestNumMagicSquaresInside(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{4, 3, 8, 4},
-				{9, 5, 1, 9},
-				{2, 7, 6, 2},
-			},
-			want: 1,
-		},
-		{
-			in: [][]int{
-				{5, 5, 5},
-				{5, 5, 5},
-				{5, 5, 5},
-			},
-			want: 0,
-		},
-		{
-			in: [][]int{
-				{1, 8, 6},
-				{10, 5, 0},
-				{4, 2, 9},
-			},
-			want: 0,
-		},
-	}
-	for _, tt := range tests {
-		got := numMagicSquaresInside(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/magical-string/README.md b/problems/magical-string/README.md
deleted file mode 100644
index 6b960806b..000000000
--- a/problems/magical-string/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sliding-window-median "Sliding Window Median")
-　　　　　　　　　　　　　　　　
-[Next >](../license-key-formatting "License Key Formatting")
-
-## [481. Magical String (Medium)](https://leetcode.com/problems/magical-string "神奇字符串")
-
-<p>A magical string <code>s</code> consists of only <code>&#39;1&#39;</code> and <code>&#39;2&#39;</code> and obeys the following rules:</p>
-
-<ul>
-	<li>The string s is magical because concatenating the number of contiguous occurrences of characters <code>&#39;1&#39;</code> and <code>&#39;2&#39;</code> generates the string <code>s</code> itself.</li>
-</ul>
-
-<p>The first few elements of <code>s</code> is <code>s = &quot;1221121221221121122&hellip;&hellip;&quot;</code>. If we group the consecutive <code>1</code>&#39;s and <code>2</code>&#39;s in <code>s</code>, it will be <code>&quot;1 22 11 2 1 22 1 22 11 2 11 22 ......&quot;</code> and the occurrences of <code>1</code>&#39;s or <code>2</code>&#39;s in each group are <code>&quot;1 2 2 1 1 2 1 2 2 1 2 2 ......&quot;</code>. You can see that the occurrence sequence is <code>s</code> itself.</p>
-
-<p>Given an integer <code>n</code>, return the number of <code>1</code>&#39;s in the first <code>n</code> number in the magical string <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The first 6 elements of magical string s is &quot;122112&quot; and it contains three 1&#39;s, so return 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/magical-string/magical_string.go b/problems/magical-string/magical_string.go
deleted file mode 100644
index 9895d2d66..000000000
--- a/problems/magical-string/magical_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem481
diff --git a/problems/magical-string/magical_string_test.go b/problems/magical-string/magical_string_test.go
deleted file mode 100644
index 9895d2d66..000000000
--- a/problems/magical-string/magical_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem481
diff --git a/problems/magnetic-force-between-two-balls/README.md b/problems/magnetic-force-between-two-balls/README.md
deleted file mode 100644
index f9fc9e02f..000000000
--- a/problems/magnetic-force-between-two-balls/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-operations-to-make-array-equal "Minimum Operations to Make Array Equal")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-days-to-eat-n-oranges "Minimum Number of Days to Eat N Oranges")
-
-## [1552. Magnetic Force Between Two Balls (Medium)](https://leetcode.com/problems/magnetic-force-between-two-balls "两球之间的磁力")
-
-<p>In the universe Earth C-137, Rick discovered a special form of magnetic force between two balls if they are put in his new invented basket. Rick has <code>n</code> empty baskets, the <code>i<sup>th</sup></code> basket is at <code>position[i]</code>, Morty has <code>m</code> balls and needs to distribute the balls into the baskets such that the <strong>minimum magnetic force</strong> between any two balls is <strong>maximum</strong>.</p>
-
-<p>Rick stated that magnetic force between two different balls at positions <code>x</code> and <code>y</code> is <code>|x - y|</code>.</p>
-
-<p>Given the integer array <code>position</code> and the integer <code>m</code>. Return <em>the required force</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/11/q3v1.jpg" style="width: 562px; height: 195px;" />
-<pre>
-<strong>Input:</strong> position = [1,2,3,4,7], m = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Distributing the 3 balls into baskets 1, 4 and 7 will make the magnetic force between ball pairs [3, 3, 6]. The minimum magnetic force is 3. We cannot achieve a larger minimum magnetic force than 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> position = [5,4,3,2,1,1000000000], m = 2
-<strong>Output:</strong> 999999999
-<strong>Explanation:</strong> We can use baskets 1 and 1000000000.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == position.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= position[i] &lt;= 10<sup>9</sup></code></li>
-	<li>All integers in <code>position</code> are <strong>distinct</strong>.</li>
-	<li><code>2 &lt;= m &lt;= position.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Minimized Maximum of Products Distributed to Any Store](../minimized-maximum-of-products-distributed-to-any-store) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you can place balls such that the answer is x then you can do it for y where y < x.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Similarly if you cannot place balls such that the answer is x then you can do it for y where y > x.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Binary search on the answer and greedily see if it is possible.
-</details>
diff --git a/problems/majority-element-ii/README.md b/problems/majority-element-ii/README.md
deleted file mode 100644
index 07c9879d8..000000000
--- a/problems/majority-element-ii/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../summary-ranges "Summary Ranges")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-smallest-element-in-a-bst "Kth Smallest Element in a BST")
-
-## [229. Majority Element II (Medium)](https://leetcode.com/problems/majority-element-ii "求众数 II")
-
-<p>Given an integer array of size <code>n</code>, find all elements that appear more than <code>&lfloor; n/3 &rfloor;</code> times.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,3]
-<strong>Output:</strong> [3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1]
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2]
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you solve the problem in linear time and in <code>O(1)</code> space?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Majority Element](../majority-element) (Easy)
-  1. [Check If a Number Is Majority Element in a Sorted Array](../check-if-a-number-is-majority-element-in-a-sorted-array) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many majority elements could it possibly have?
-<br/>
-Do you have a better hint? <a href="mailto:admin@leetcode.com?subject=Hints for Majority Element II" target="_blank">Suggest it</a>!
-</details>
diff --git a/problems/majority-element-ii/majority_element_ii.go b/problems/majority-element-ii/majority_element_ii.go
deleted file mode 100644
index 66cf0b90d..000000000
--- a/problems/majority-element-ii/majority_element_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem229
diff --git a/problems/majority-element-ii/majority_element_ii_test.go b/problems/majority-element-ii/majority_element_ii_test.go
deleted file mode 100644
index 66cf0b90d..000000000
--- a/problems/majority-element-ii/majority_element_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem229
diff --git a/problems/majority-element/README.md b/problems/majority-element/README.md
deleted file mode 100644
index 0e1ec3228..000000000
--- a/problems/majority-element/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../excel-sheet-column-title "Excel Sheet Column Title")
-　　　　　　　　　　　　　　　　
-[Next >](../two-sum-iii-data-structure-design "Two Sum III - Data structure design")
-
-## [169. Majority Element (Easy)](https://leetcode.com/problems/majority-element "多数元素")
-
-<p>Given an array <code>nums</code> of size <code>n</code>, return <em>the majority element</em>.</p>
-
-<p>The majority element is the element that appears more than <code>&lfloor;n / 2&rfloor;</code> times. You may assume that the majority element always exists in the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [3,2,3]
-<strong>Output:</strong> 3
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [2,2,1,1,1,2,2]
-<strong>Output:</strong> 2
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow-up:</strong> Could you solve the problem in linear time and in <code>O(1)</code> space?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Majority Element II](../majority-element-ii) (Medium)
-  1. [Check If a Number Is Majority Element in a Sorted Array](../check-if-a-number-is-majority-element-in-a-sorted-array) (Easy)
diff --git a/problems/majority-element/majority_element.go b/problems/majority-element/majority_element.go
deleted file mode 100644
index afc141c5f..000000000
--- a/problems/majority-element/majority_element.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem169
-
-func majorityElement(nums []int) int {
-	ans, count := 0, 0
-	for _, n := range nums {
-		if n == ans {
-			count++
-		} else {
-			count--
-		}
-		if count <= 0 {
-			ans = n
-			count = 1
-		}
-	}
-	return ans
-}
diff --git a/problems/majority-element/majority_element_test.go b/problems/majority-element/majority_element_test.go
deleted file mode 100644
index 168a96e87..000000000
--- a/problems/majority-element/majority_element_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem169
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMajorityElement(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 2, 3},
-			want: 3,
-		},
-		{
-			in:   []int{2, 2, 1, 1, 1, 2, 2},
-			want: 2,
-		},
-		{
-			in:   []int{2, 2, 2, 2, 1, 1, 1},
-			want: 2,
-		},
-		{
-			in:   []int{1},
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := majorityElement(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/make-array-strictly-increasing/README.md b/problems/make-array-strictly-increasing/README.md
deleted file mode 100644
index 42344907a..000000000
--- a/problems/make-array-strictly-increasing/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-subarray-sum-with-one-deletion "Maximum Subarray Sum with One Deletion")
-　　　　　　　　　　　　　　　　
-[Next >](../design-bounded-blocking-queue "Design Bounded Blocking Queue")
-
-## [1187. Make Array Strictly Increasing (Hard)](https://leetcode.com/problems/make-array-strictly-increasing "使数组严格递增")
-
-<p>Given two integer arrays&nbsp;<code>arr1</code> and <code>arr2</code>, return the minimum number of operations (possibly zero) needed&nbsp;to make <code>arr1</code> strictly increasing.</p>
-
-<p>In one operation, you can choose two indices&nbsp;<code>0 &lt;=&nbsp;i &lt; arr1.length</code>&nbsp;and&nbsp;<code>0 &lt;= j &lt; arr2.length</code>&nbsp;and do the assignment&nbsp;<code>arr1[i] = arr2[j]</code>.</p>
-
-<p>If there is no way to make&nbsp;<code>arr1</code>&nbsp;strictly increasing,&nbsp;return&nbsp;<code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [1,5,3,6,7], arr2 = [1,3,2,4]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Replace <code>5</code> with <code>2</code>, then <code>arr1 = [1, 2, 3, 6, 7]</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [1,5,3,6,7], arr2 = [4,3,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Replace <code>5</code> with <code>3</code> and then replace <code>3</code> with <code>4</code>. <code>arr1 = [1, 3, 4, 6, 7]</code>.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [1,5,3,6,7], arr2 = [1,6,3,3]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> You can&#39;t make <code>arr1</code> strictly increasing.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr1.length, arr2.length &lt;= 2000</code></li>
-	<li><code>0 &lt;= arr1[i], arr2[i] &lt;= 10^9</code></li>
-</ul>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The state would be the index in arr1 and the index of the previous element in arr2 after sorting it and removing duplicates.
-</details>
diff --git a/problems/make-sum-divisible-by-p/README.md b/problems/make-sum-divisible-by-p/README.md
deleted file mode 100644
index bcdc0d891..000000000
--- a/problems/make-sum-divisible-by-p/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-sum-obtained-of-any-permutation "Maximum Sum Obtained of Any Permutation")
-　　　　　　　　　　　　　　　　
-[Next >](../strange-printer-ii "Strange Printer II")
-
-## [1590. Make Sum Divisible by P (Medium)](https://leetcode.com/problems/make-sum-divisible-by-p "使数组和能被 P 整除")
-
-<p>Given an array of positive integers <code>nums</code>, remove the <strong>smallest</strong> subarray (possibly <strong>empty</strong>) such that the <strong>sum</strong> of the remaining elements is divisible by <code>p</code>. It is <strong>not</strong> allowed to remove the whole array.</p>
-
-<p>Return <em>the length of the smallest subarray that you need to remove, or </em><code>-1</code><em> if it&#39;s impossible</em>.</p>
-
-<p>A <strong>subarray</strong> is defined as a contiguous block of elements in the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,4,2], p = 6
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The sum of the elements in nums is 10, which is not divisible by 6. We can remove the subarray [4], and the sum of the remaining elements is 6, which is divisible by 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [6,3,5,2], p = 9
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We cannot remove a single element to get a sum divisible by 9. The best way is to remove the subarray [5,2], leaving us with [6,3] with sum 9.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3], p = 3
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Here the sum is 6. which is already divisible by 3. Thus we do not need to remove anything.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= p &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use prefix sums to calculate the subarray sums.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Suppose you know the remainder for the sum of the entire array. How does removing a subarray affect that remainder? What remainder does the subarray need to have in order to make the rest of the array sum up to be divisible by k?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use a map to keep track of the rightmost index for every prefix sum % p.
-</details>
diff --git a/problems/make-the-string-great/README.md b/problems/make-the-string-great/README.md
deleted file mode 100644
index 2f6e82d68..000000000
--- a/problems/make-the-string-great/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fix-product-name-format "Fix Product Name Format")
-　　　　　　　　　　　　　　　　
-[Next >](../find-kth-bit-in-nth-binary-string "Find Kth Bit in Nth Binary String")
-
-## [1544. Make The String Great (Easy)](https://leetcode.com/problems/make-the-string-great "整理字符串")
-
-<p>Given a string <code>s</code> of lower and upper case English letters.</p>
-
-<p>A good string is a string which doesn&#39;t have <strong>two adjacent characters</strong> <code>s[i]</code> and <code>s[i + 1]</code> where:</p>
-
-<ul>
-	<li><code>0 &lt;= i &lt;= s.length - 2</code></li>
-	<li><code>s[i]</code> is a lower-case letter and <code>s[i + 1]</code> is the same letter but in upper-case or <strong>vice-versa</strong>.</li>
-</ul>
-
-<p>To make the string good, you can choose <strong>two adjacent</strong> characters that make the string bad and remove them. You can keep doing this until the string becomes good.</p>
-
-<p>Return <em>the string</em> after making it good. The answer is guaranteed to be unique under the given constraints.</p>
-
-<p><strong>Notice</strong> that an empty string is also good.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leEeetcode&quot;
-<strong>Output:</strong> &quot;leetcode&quot;
-<strong>Explanation:</strong> In the first step, either you choose i = 1 or i = 2, both will result &quot;leEeetcode&quot; to be reduced to &quot;leetcode&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abBAcC&quot;
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> We have many possible scenarios, and all lead to the same answer. For example:
-&quot;abBAcC&quot; --&gt; &quot;aAcC&quot; --&gt; &quot;cC&quot; --&gt; &quot;&quot;
-&quot;abBAcC&quot; --&gt; &quot;abBA&quot; --&gt; &quot;aA&quot; --&gt; &quot;&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;s&quot;
-<strong>Output:</strong> &quot;s&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> contains only lower and upper case English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The order you choose 2 characters to remove doesn't matter.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep applying the mentioned step to s till the length of the string is not changed.
-</details>
diff --git a/problems/make-the-xor-of-all-segments-equal-to-zero/README.md b/problems/make-the-xor-of-all-segments-equal-to-zero/README.md
deleted file mode 100644
index 050bb69d1..000000000
--- a/problems/make-the-xor-of-all-segments-equal-to-zero/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-restricted-paths-from-first-to-last-node "Number of Restricted Paths From First to Last Node")
-　　　　　　　　　　　　　　　　
-[Next >](../maximize-the-beauty-of-the-garden "Maximize the Beauty of the Garden")
-
-## [1787. Make the XOR of All Segments Equal to Zero (Hard)](https://leetcode.com/problems/make-the-xor-of-all-segments-equal-to-zero "使所有区间的异或结果为零")
-
-<p>You are given an array <code>nums</code>​​​ and an integer <code>k</code>​​​​​. The <font face="monospace">XOR</font> of a segment <code>[left, right]</code> where <code>left &lt;= right</code> is the <code>XOR</code> of all the elements with indices between <code>left</code> and <code>right</code>, inclusive: <code>nums[left] XOR nums[left+1] XOR ... XOR nums[right]</code>.</p>
-
-<p>Return <em>the minimum number of elements to change in the array </em>such that the <code>XOR</code> of all segments of size <code>k</code>​​​​​​ is equal to zero.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,0,3,0], k = 1
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>Modify the array from [<u><strong>1</strong></u>,<u><strong>2</strong></u>,0,<u><strong>3</strong></u>,0] to from [<u><strong>0</strong></u>,<u><strong>0</strong></u>,0,<u><strong>0</strong></u>,0].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,4,5,2,1,7,3,4,7], k = 3
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>Modify the array from [3,4,<strong><u>5</u></strong>,<strong><u>2</u></strong>,<strong><u>1</u></strong>,7,3,4,7] to [3,4,<strong><u>7</u></strong>,<strong><u>3</u></strong>,<strong><u>4</u></strong>,7,3,4,7].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,4,1,2,5,1,2,6], k = 3
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>Modify the array from [1,2,<strong><u>4,</u></strong>1,2,<strong><u>5</u></strong>,1,2,<strong><u>6</u></strong>] to [1,2,<strong><u>3</u></strong>,1,2,<strong><u>3</u></strong>,1,2,<strong><u>3</u></strong>].</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= nums.length &lt;= 2000</code></li>
-	<li><code>​​​​​​0 &lt;= nums[i] &lt; 2<sup>10</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's note that for the XOR of all segments with size K to be equal to zeros, nums[i] has to be equal to nums[i+k]
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Basically, we need to make the first K elements have XOR = 0 and then modify them.
-</details>
diff --git a/problems/make-two-arrays-equal-by-reversing-sub-arrays/README.md b/problems/make-two-arrays-equal-by-reversing-sub-arrays/README.md
deleted file mode 100644
index 3f98c203d..000000000
--- a/problems/make-two-arrays-equal-by-reversing-sub-arrays/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rectangles-area "Rectangles Area")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-a-string-contains-all-binary-codes-of-size-k "Check If a String Contains All Binary Codes of Size K")
-
-## [1460. Make Two Arrays Equal by Reversing Sub-arrays (Easy)](https://leetcode.com/problems/make-two-arrays-equal-by-reversing-sub-arrays "通过翻转子数组使两个数组相等")
-
-<p>You are given two integer arrays of equal length <code>target</code> and <code>arr</code>. In one step, you can select any <strong>non-empty sub-array</strong> of <code>arr</code> and reverse it. You are allowed to make any number of steps.</p>
-
-<p>Return <code>true</code> <em>if you can make </em><code>arr</code><em> equal to </em><code>target</code><em>&nbsp;or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [1,2,3,4], arr = [2,4,1,3]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can follow the next steps to convert arr to target:
-1- Reverse sub-array [2,4,1], arr becomes [1,4,2,3]
-2- Reverse sub-array [4,2], arr becomes [1,2,4,3]
-3- Reverse sub-array [4,3], arr becomes [1,2,3,4]
-There are multiple ways to convert arr to target, this is not the only way to do so.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [7], arr = [7]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> arr is equal to target without any reverses.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [3,7,9], arr = [3,7,11]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> arr does not have value 9 and it can never be converted to target.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>target.length == arr.length</code></li>
-	<li><code>1 &lt;= target.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= target[i] &lt;= 1000</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Each element of target should have a corresponding element in arr, and if it doesn't have a corresponding element, return false.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To solve it easiely you can sort the two arrays and check if they are equal.
-</details>
diff --git a/problems/making-a-large-island/README.md b/problems/making-a-large-island/README.md
deleted file mode 100644
index ecb878491..000000000
--- a/problems/making-a-large-island/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../most-profit-assigning-work "Most Profit Assigning Work")
-　　　　　　　　　　　　　　　　
-[Next >](../count-unique-characters-of-all-substrings-of-a-given-string "Count Unique Characters of All Substrings of a Given String")
-
-## [827. Making A Large Island (Hard)](https://leetcode.com/problems/making-a-large-island "最大人工岛")
-
-<p>You are given an <code>n x n</code> binary matrix <code>grid</code>. You are allowed to change <strong>at most one</strong> <code>0</code> to be <code>1</code>.</p>
-
-<p>Return <em>the size of the largest <strong>island</strong> in</em> <code>grid</code> <em>after applying this operation</em>.</p>
-
-<p>An <strong>island</strong> is a 4-directionally connected group of <code>1</code>s.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,0],[0,1]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Change one 0 to 1 and connect two 1s, then we get an island with area = 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1],[1,0]]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>Change the 0 to 1 and make the island bigger, only one island with area = 4.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1],[1,1]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Can&#39;t change any 0 to 1, only one island with area = 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/making-a-large-island/making_a_large_island.go b/problems/making-a-large-island/making_a_large_island.go
deleted file mode 100644
index 7e8e28d5e..000000000
--- a/problems/making-a-large-island/making_a_large_island.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem827
diff --git a/problems/making-a-large-island/making_a_large_island_test.go b/problems/making-a-large-island/making_a_large_island_test.go
deleted file mode 100644
index 7e8e28d5e..000000000
--- a/problems/making-a-large-island/making_a_large_island_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem827
diff --git a/problems/making-file-names-unique/README.md b/problems/making-file-names-unique/README.md
deleted file mode 100644
index 0b8995d41..000000000
--- a/problems/making-file-names-unique/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../xor-operation-in-an-array "XOR Operation in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../avoid-flood-in-the-city "Avoid Flood in The City")
-
-## [1487. Making File Names Unique (Medium)](https://leetcode.com/problems/making-file-names-unique "保证文件名唯一")
-
-<p>Given an array of strings <code>names</code> of size <code>n</code>. You will create <code>n</code> folders in your file system <strong>such that</strong>, at the <code>i<sup>th</sup></code> minute, you will create a folder with the name <code>names[i]</code>.</p>
-
-<p>Since two files <strong>cannot</strong> have the same name, if you enter a folder name that was previously used, the system will have a suffix addition to its name in the form of <code>(k)</code>, where, <code>k</code> is the <strong>smallest positive integer</strong> such that the obtained name remains unique.</p>
-
-<p>Return <em>an array of strings of length </em><code>n</code> where <code>ans[i]</code> is the actual name the system will assign to the <code>i<sup>th</sup></code> folder when you create it.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> names = [&quot;pes&quot;,&quot;fifa&quot;,&quot;gta&quot;,&quot;pes(2019)&quot;]
-<strong>Output:</strong> [&quot;pes&quot;,&quot;fifa&quot;,&quot;gta&quot;,&quot;pes(2019)&quot;]
-<strong>Explanation:</strong> Let&#39;s see how the file system creates folder names:
-&quot;pes&quot; --&gt; not assigned before, remains &quot;pes&quot;
-&quot;fifa&quot; --&gt; not assigned before, remains &quot;fifa&quot;
-&quot;gta&quot; --&gt; not assigned before, remains &quot;gta&quot;
-&quot;pes(2019)&quot; --&gt; not assigned before, remains &quot;pes(2019)&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> names = [&quot;gta&quot;,&quot;gta(1)&quot;,&quot;gta&quot;,&quot;avalon&quot;]
-<strong>Output:</strong> [&quot;gta&quot;,&quot;gta(1)&quot;,&quot;gta(2)&quot;,&quot;avalon&quot;]
-<strong>Explanation:</strong> Let&#39;s see how the file system creates folder names:
-&quot;gta&quot; --&gt; not assigned before, remains &quot;gta&quot;
-&quot;gta(1)&quot; --&gt; not assigned before, remains &quot;gta(1)&quot;
-&quot;gta&quot; --&gt; the name is reserved, system adds (k), since &quot;gta(1)&quot; is also reserved, systems put k = 2. it becomes &quot;gta(2)&quot;
-&quot;avalon&quot; --&gt; not assigned before, remains &quot;avalon&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> names = [&quot;onepiece&quot;,&quot;onepiece(1)&quot;,&quot;onepiece(2)&quot;,&quot;onepiece(3)&quot;,&quot;onepiece&quot;]
-<strong>Output:</strong> [&quot;onepiece&quot;,&quot;onepiece(1)&quot;,&quot;onepiece(2)&quot;,&quot;onepiece(3)&quot;,&quot;onepiece(4)&quot;]
-<strong>Explanation:</strong> When the last folder is created, the smallest positive valid k is 4, and it becomes &quot;onepiece(4)&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= names.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= names[i].length &lt;= 20</code></li>
-	<li><code>names[i]</code> consists of lowercase English letters, digits, and/or round brackets.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep a map of each name and the smallest valid integer that can be appended as a suffix to it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the name is not present in the map, you can use it without adding any suffixes.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If the name is present in the map, append the smallest proper suffix, and add the new name to the map.
-</details>
diff --git a/problems/managers-with-at-least-5-direct-reports/README.md b/problems/managers-with-at-least-5-direct-reports/README.md
deleted file mode 100644
index 56112b8e5..000000000
--- a/problems/managers-with-at-least-5-direct-reports/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../median-employee-salary "Median Employee Salary")
-　　　　　　　　　　　　　　　　
-[Next >](../find-median-given-frequency-of-numbers "Find Median Given Frequency of Numbers")
-
-## [570. Managers with at Least 5 Direct Reports (Medium)](https://leetcode.com/problems/managers-with-at-least-5-direct-reports "至少有5名直接下属的经理")
-
-<p>The <code>Employee</code> table holds all employees including their managers. Every employee has an Id, and there is also a column for the manager Id.</p>
-
-<pre>
-+------+----------+-----------+----------+
-|Id    |Name 	  |Department |ManagerId |
-+------+----------+-----------+----------+
-|101   |John 	  |A 	      |null      |
-|102   |Dan 	  |A 	      |101       |
-|103   |James 	  |A 	      |101       |
-|104   |Amy 	  |A 	      |101       |
-|105   |Anne 	  |A 	      |101       |
-|106   |Ron 	  |B 	      |101       |
-+------+----------+-----------+----------+
-</pre>
-
-<p>Given the <code>Employee</code> table, write a SQL query that finds out managers with at least 5 direct report. For the above table, your SQL query should return:</p>
-
-<pre>
-+-------+
-| Name  |
-+-------+
-| John  |
-+-------+
-</pre>
-
-<p><b>Note:</b><br />
-No one would report to himself.</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to get all the mangerIDs that have count bigger than 5
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the last hint's result as a table and do join with origin table at id equals to managerId
-</details>
-
-<details>
-<summary>Hint 3</summary>
-This is a very good example to show the performance of SQL code. Try to work out other solutions and you may be surprised by running time difference.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-If your solution uses 'IN' function and runs more than 5 seconds, try to optimize it by using 'JOIN' instead.
-</details>
diff --git a/problems/managers-with-at-least-5-direct-reports/managers_with_at_least_5_direct_reports.sql b/problems/managers-with-at-least-5-direct-reports/managers_with_at_least_5_direct_reports.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/managers-with-at-least-5-direct-reports/managers_with_at_least_5_direct_reports.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/managers-with-at-least-5-direct-reports/mysql_schemas.sql b/problems/managers-with-at-least-5-direct-reports/mysql_schemas.sql
deleted file mode 100644
index 1c7195415..000000000
--- a/problems/managers-with-at-least-5-direct-reports/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Employee (Id int, Name varchar(255), Department varchar(255), ManagerId int);
-Truncate table Employee;
-insert into Employee (Id, Name, Department, ManagerId) values ('101', 'John', 'A', 'None');
-insert into Employee (Id, Name, Department, ManagerId) values ('102', 'Dan', 'A', '101');
-insert into Employee (Id, Name, Department, ManagerId) values ('103', 'James', 'A', '101');
-insert into Employee (Id, Name, Department, ManagerId) values ('104', 'Amy', 'A', '101');
-insert into Employee (Id, Name, Department, ManagerId) values ('105', 'Anne', 'A', '101');
-insert into Employee (Id, Name, Department, ManagerId) values ('106', 'Ron', 'B', '101');
diff --git a/problems/map-of-highest-peak/README.md b/problems/map-of-highest-peak/README.md
deleted file mode 100644
index e87e23d08..000000000
--- a/problems/map-of-highest-peak/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../form-array-by-concatenating-subarrays-of-another-array "Form Array by Concatenating Subarrays of Another Array")
-　　　　　　　　　　　　　　　　
-[Next >](../tree-of-coprimes "Tree of Coprimes")
-
-## [1765. Map of Highest Peak (Medium)](https://leetcode.com/problems/map-of-highest-peak "地图中的最高点")
-
-<p>You are given an integer matrix <code>isWater</code> of size <code>m x n</code> that represents a map of <strong>land</strong> and <strong>water</strong> cells.</p>
-
-<ul>
-	<li>If <code>isWater[i][j] == 0</code>, cell <code>(i, j)</code> is a <strong>land</strong> cell.</li>
-	<li>If <code>isWater[i][j] == 1</code>, cell <code>(i, j)</code> is a <strong>water</strong> cell.</li>
-</ul>
-
-<p>You must assign each cell a height in a way that follows these rules:</p>
-
-<ul>
-	<li>The height of each cell must be non-negative.</li>
-	<li>If the cell is a <strong>water</strong> cell, its height must be <code>0</code>.</li>
-	<li>Any two adjacent cells must have an absolute height difference of <strong>at most</strong> <code>1</code>. A cell is adjacent to another cell if the former is directly north, east, south, or west of the latter (i.e., their sides are touching).</li>
-</ul>
-
-<p>Find an assignment of heights such that the maximum height in the matrix is <strong>maximized</strong>.</p>
-
-<p>Return <em>an integer matrix </em><code>height</code><em> of size </em><code>m x n</code><em> where </em><code>height[i][j]</code><em> is cell </em><code>(i, j)</code><em>&#39;s height. If there are multiple solutions, return <strong>any</strong> of them</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2021/01/10/screenshot-2021-01-11-at-82045-am.png" style="width: 220px; height: 219px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> isWater = [[0,1],[0,0]]
-<strong>Output:</strong> [[1,0],[2,1]]
-<strong>Explanation:</strong> The image shows the assigned heights of each cell.
-The blue cell is the water cell, and the green cells are the land cells.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2021/01/10/screenshot-2021-01-11-at-82050-am.png" style="width: 300px; height: 296px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> isWater = [[0,0,1],[1,0,0],[0,0,0]]
-<strong>Output:</strong> [[1,1,0],[0,1,1],[1,2,2]]
-<strong>Explanation:</strong> A height of 2 is the maximum possible height of any assignment.
-Any height assignment that has a maximum height of 2 while still meeting the rules will also be accepted.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == isWater.length</code></li>
-	<li><code>n == isWater[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 1000</code></li>
-	<li><code>isWater[i][j]</code> is <code>0</code> or <code>1</code>.</li>
-	<li>There is at least <strong>one</strong> water cell.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Set each water cell to be 0. The height of each cell is limited by its closest water cell.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Perform a multi-source BFS with all the water cells as sources.
-</details>
diff --git a/problems/map-sum-pairs/README.md b/problems/map-sum-pairs/README.md
deleted file mode 100644
index ffca94185..000000000
--- a/problems/map-sum-pairs/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../implement-magic-dictionary "Implement Magic Dictionary")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-parenthesis-string "Valid Parenthesis String")
-
-## [677. Map Sum Pairs (Medium)](https://leetcode.com/problems/map-sum-pairs "键值映射")
-
-<p>Design a map that allows you to do the following:</p>
-
-<ul>
-	<li>Maps a string key to a given value.</li>
-	<li>Returns the sum of the values that have a key with a prefix equal to a given string.</li>
-</ul>
-
-<p>Implement the <code>MapSum</code> class:</p>
-
-<ul>
-	<li><code>MapSum()</code> Initializes the <code>MapSum</code> object.</li>
-	<li><code>void insert(String key, int val)</code> Inserts the <code>key-val</code> pair into the map. If the <code>key</code> already existed, the original <code>key-value</code> pair will be overridden to the new one.</li>
-	<li><code>int sum(string prefix)</code> Returns the sum of all the pairs&#39; value whose <code>key</code> starts with the <code>prefix</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MapSum&quot;, &quot;insert&quot;, &quot;sum&quot;, &quot;insert&quot;, &quot;sum&quot;]
-[[], [&quot;apple&quot;, 3], [&quot;ap&quot;], [&quot;app&quot;, 2], [&quot;ap&quot;]]
-<strong>Output</strong>
-[null, null, 3, null, 5]
-
-<strong>Explanation</strong>
-MapSum mapSum = new MapSum();
-mapSum.insert(&quot;apple&quot;, 3);  
-mapSum.sum(&quot;ap&quot;);           // return 3 (<u>ap</u>ple = 3)
-mapSum.insert(&quot;app&quot;, 2);    
-mapSum.sum(&quot;ap&quot;);           // return 5 (<u>ap</u>ple + <u>ap</u>p = 3 + 2 = 5)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= key.length, prefix.length &lt;= 50</code></li>
-	<li><code>key</code> and <code>prefix</code> consist of only lowercase English letters.</li>
-	<li><code>1 &lt;= val &lt;= 1000</code></li>
-	<li>At most <code>50</code> calls will be made to <code>insert</code> and <code>sum</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
diff --git a/problems/map-sum-pairs/map_sum_pairs.go b/problems/map-sum-pairs/map_sum_pairs.go
deleted file mode 100644
index 9b55f6d20..000000000
--- a/problems/map-sum-pairs/map_sum_pairs.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem677
diff --git a/problems/map-sum-pairs/map_sum_pairs_test.go b/problems/map-sum-pairs/map_sum_pairs_test.go
deleted file mode 100644
index 9b55f6d20..000000000
--- a/problems/map-sum-pairs/map_sum_pairs_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem677
diff --git a/problems/market-analysis-i/README.md b/problems/market-analysis-i/README.md
deleted file mode 100644
index db202cb38..000000000
--- a/problems/market-analysis-i/README.md
+++ /dev/null
@@ -1,107 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../online-majority-element-in-subarray "Online Majority Element In Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../market-analysis-ii "Market Analysis II")
-
-## [1158. Market Analysis I (Medium)](https://leetcode.com/problems/market-analysis-i "市场分析 I")
-
-<p>Table: <code>Users</code></p>
-
-<pre>
-+----------------+---------+
-| Column Name    | Type    |
-+----------------+---------+
-| user_id        | int     |
-| join_date      | date    |
-| favorite_brand | varchar |
-+----------------+---------+
-user_id is the primary key of this table.
-This table has the info of the users of an online shopping website where users can sell and buy items.</pre>
-
-<p>Table: <code>Orders</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| order_id      | int     |
-| order_date    | date    |
-| item_id       | int     |
-| buyer_id      | int     |
-| seller_id     | int     |
-+---------------+---------+
-order_id is the primary key of this table.
-item_id is a foreign key to the Items table.
-buyer_id and seller_id are foreign keys to the Users table.
-</pre>
-
-<p>Table: <code>Items</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| item_id       | int     |
-| item_brand    | varchar |
-+---------------+---------+
-item_id is the primary key of this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find for each user, the join date and the number of orders they made as a buyer in <strong>2019</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Users table:
-+---------+------------+----------------+
-| user_id | join_date  | favorite_brand |
-+---------+------------+----------------+
-| 1       | 2018-01-01 | Lenovo         |
-| 2       | 2018-02-09 | Samsung        |
-| 3       | 2018-01-19 | LG             |
-| 4       | 2018-05-21 | HP             |
-+---------+------------+----------------+
-
-Orders table:
-+----------+------------+---------+----------+-----------+
-| order_id | order_date | item_id | buyer_id | seller_id |
-+----------+------------+---------+----------+-----------+
-| 1        | 2019-08-01 | 4       | 1        | 2         |
-| 2        | 2018-08-02 | 2       | 1        | 3         |
-| 3        | 2019-08-03 | 3       | 2        | 3         |
-| 4        | 2018-08-04 | 1       | 4        | 2         |
-| 5        | 2018-08-04 | 1       | 3        | 4         |
-| 6        | 2019-08-05 | 2       | 2        | 4         |
-+----------+------------+---------+----------+-----------+
-
-Items table:
-+---------+------------+
-| item_id | item_brand |
-+---------+------------+
-| 1       | Samsung    |
-| 2       | Lenovo     |
-| 3       | LG         |
-| 4       | HP         |
-+---------+------------+
-
-Result table:
-+-----------+------------+----------------+
-| buyer_id  | join_date  | orders_in_2019 |
-+-----------+------------+----------------+
-| 1         | 2018-01-01 | 1              |
-| 2         | 2018-02-09 | 2              |
-| 3         | 2018-01-19 | 0              |
-| 4         | 2018-05-21 | 0              |
-+-----------+------------+----------------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/market-analysis-i/mysql_schemas.sql b/problems/market-analysis-i/mysql_schemas.sql
deleted file mode 100644
index 82f724345..000000000
--- a/problems/market-analysis-i/mysql_schemas.sql
+++ /dev/null
@@ -1,20 +0,0 @@
-Create table If Not Exists Users (user_id int, join_date date, favorite_brand varchar(10));
-Create table If Not Exists Orders (order_id int, order_date date, item_id int, buyer_id int, seller_id int);
-Create table If Not Exists Items (item_id int, item_brand varchar(10));
-Truncate table Users;
-insert into Users (user_id, join_date, favorite_brand) values ('1', '2018-01-01', 'Lenovo');
-insert into Users (user_id, join_date, favorite_brand) values ('2', '2018-02-09', 'Samsung');
-insert into Users (user_id, join_date, favorite_brand) values ('3', '2018-01-19', 'LG');
-insert into Users (user_id, join_date, favorite_brand) values ('4', '2018-05-21', 'HP');
-Truncate table Orders;
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('1', '2019-08-01', '4', '1', '2');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('2', '2018-08-02', '2', '1', '3');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('3', '2019-08-03', '3', '2', '3');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('4', '2018-08-04', '1', '4', '2');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('5', '2018-08-04', '1', '3', '4');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('6', '2019-08-05', '2', '2', '4');
-Truncate table Items;
-insert into Items (item_id, item_brand) values ('1', 'Samsung');
-insert into Items (item_id, item_brand) values ('2', 'Lenovo');
-insert into Items (item_id, item_brand) values ('3', 'LG');
-insert into Items (item_id, item_brand) values ('4', 'HP');
diff --git a/problems/market-analysis-ii/README.md b/problems/market-analysis-ii/README.md
deleted file mode 100644
index 90625782d..000000000
--- a/problems/market-analysis-ii/README.md
+++ /dev/null
@@ -1,112 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../market-analysis-i "Market Analysis I")
-　　　　　　　　　　　　　　　　
-[Next >](../find-words-that-can-be-formed-by-characters "Find Words That Can Be Formed by Characters")
-
-## [1159. Market Analysis II (Hard)](https://leetcode.com/problems/market-analysis-ii "市场分析 II")
-
-<p>Table: <code>Users</code></p>
-
-<pre>
-+----------------+---------+
-| Column Name    | Type    |
-+----------------+---------+
-| user_id        | int     |
-| join_date      | date    |
-| favorite_brand | varchar |
-+----------------+---------+
-user_id is the primary key of this table.
-This table has the info of the users of an online shopping website where users can sell and buy items.</pre>
-
-<p>Table: <code>Orders</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| order_id      | int     |
-| order_date    | date    |
-| item_id       | int     |
-| buyer_id      | int     |
-| seller_id     | int     |
-+---------------+---------+
-order_id is the primary key of this table.
-item_id is a foreign key to the Items table.
-buyer_id and seller_id are foreign keys to the Users table.
-</pre>
-
-<p>Table: <code>Items</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| item_id       | int     |
-| item_brand    | varchar |
-+---------------+---------+
-item_id is the primary key of this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find for each user, whether the brand of the second item (by date) they sold&nbsp;is&nbsp;their favorite brand. If a user sold less than two items, report the answer&nbsp;for that user as no.</p>
-
-<p>It is guaranteed that no seller sold more than one item on a day.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Users table:
-+---------+------------+----------------+
-| user_id | join_date  | favorite_brand |
-+---------+------------+----------------+
-| 1       | 2019-01-01 | Lenovo         |
-| 2       | 2019-02-09 | Samsung        |
-| 3       | 2019-01-19 | LG             |
-| 4       | 2019-05-21 | HP             |
-+---------+------------+----------------+
-
-Orders table:
-+----------+------------+---------+----------+-----------+
-| order_id | order_date | item_id | buyer_id | seller_id |
-+----------+------------+---------+----------+-----------+
-| 1        | 2019-08-01 | 4       | 1        | 2         |
-| 2        | 2019-08-02 | 2       | 1        | 3         |
-| 3        | 2019-08-03 | 3       | 2        | 3         |
-| 4        | 2019-08-04 | 1       | 4        | 2         |
-| 5        | 2019-08-04 | 1       | 3        | 4         |
-| 6        | 2019-08-05 | 2       | 2        | 4         |
-+----------+------------+---------+----------+-----------+
-
-Items table:
-+---------+------------+
-| item_id | item_brand |
-+---------+------------+
-| 1       | Samsung    |
-| 2       | Lenovo     |
-| 3       | LG         |
-| 4       | HP         |
-+---------+------------+
-
-Result table:
-+-----------+--------------------+
-| seller_id | 2nd_item_fav_brand |
-+-----------+--------------------+
-| 1         | no                 |
-| 2         | yes                |
-| 3         | yes                |
-| 4         | no                 |
-+-----------+--------------------+
-
-The answer for the user with id 1 is no because they sold nothing.
-The answer for the users with id 2 and 3 is yes because the brands of their second sold items are their favorite brands.
-The answer for the user with id 4 is no because the brand of their second sold item is not their favorite brand.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/market-analysis-ii/mysql_schemas.sql b/problems/market-analysis-ii/mysql_schemas.sql
deleted file mode 100644
index 1eea2fa16..000000000
--- a/problems/market-analysis-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,20 +0,0 @@
-Create table If Not Exists Users (user_id int, join_date date, favorite_brand varchar(10));
-Create table If Not Exists Orders (order_id int, order_date date, item_id int, buyer_id int, seller_id int);
-Create table If Not Exists Items (item_id int, item_brand varchar(10));
-Truncate table Users;
-insert into Users (user_id, join_date, favorite_brand) values ('1', '2019-01-01', 'Lenovo');
-insert into Users (user_id, join_date, favorite_brand) values ('2', '2019-02-09', 'Samsung');
-insert into Users (user_id, join_date, favorite_brand) values ('3', '2019-01-19', 'LG');
-insert into Users (user_id, join_date, favorite_brand) values ('4', '2019-05-21', 'HP');
-Truncate table Orders;
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('1', '2019-08-01', '4', '1', '2');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('2', '2019-08-02', '2', '1', '3');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('3', '2019-08-03', '3', '2', '3');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('4', '2019-08-04', '1', '4', '2');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('5', '2019-08-04', '1', '3', '4');
-insert into Orders (order_id, order_date, item_id, buyer_id, seller_id) values ('6', '2019-08-05', '2', '2', '4');
-Truncate table Items;
-insert into Items (item_id, item_brand) values ('1', 'Samsung');
-insert into Items (item_id, item_brand) values ('2', 'Lenovo');
-insert into Items (item_id, item_brand) values ('3', 'LG');
-insert into Items (item_id, item_brand) values ('4', 'HP');
diff --git a/problems/masking-personal-information/README.md b/problems/masking-personal-information/README.md
deleted file mode 100644
index 7269126a5..000000000
--- a/problems/masking-personal-information/README.md
+++ /dev/null
@@ -1,119 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../positions-of-large-groups "Positions of Large Groups")
-　　　　　　　　　　　　　　　　
-[Next >](../flipping-an-image "Flipping an Image")
-
-## [831. Masking Personal Information (Medium)](https://leetcode.com/problems/masking-personal-information "隐藏个人信息")
-
-<p>You are given a personal information string <code>s</code>, representing either an <strong>email address</strong> or a <strong>phone number</strong>. Return <em>the <strong>masked</strong> personal information using the below rules</em>.</p>
-
-<p><u><strong>Email address:</strong></u></p>
-
-<p>An email address is:</p>
-
-<ul>
-	<li>A <strong>name</strong> consisting of uppercase and lowercase English letters, followed by</li>
-	<li>The <code>&#39;@&#39;</code> symbol, followed by</li>
-	<li>The <strong>domain</strong> consisting of uppercase and lowercase English letters with a dot <code>&#39;.&#39;</code> somewhere in the middle (not the first or last character).</li>
-</ul>
-
-<p>To mask an email:</p>
-
-<ul>
-	<li>The uppercase letters in the <strong>name</strong> and <strong>domain</strong> must be converted to lowercase letters.</li>
-	<li>The middle letters of the <strong>name</strong> (i.e., all but the first and last letters) must be replaced by 5 asterisks <code>&quot;*****&quot;</code>.</li>
-</ul>
-
-<p><u><strong>Phone number:</strong></u></p>
-
-<p>A phone number is formatted as follows:</p>
-
-<ul>
-	<li>The phone number contains 10-13 digits.</li>
-	<li>The last 10 digits make up the <strong>local number</strong>.</li>
-	<li>The remaining 0-3 digits, in the beginning, make up the <strong>country code</strong>.</li>
-	<li><strong>Separation characters</strong> from the set <code>{&#39;+&#39;, &#39;-&#39;, &#39;(&#39;, &#39;)&#39;, &#39; &#39;}</code> separate the above digits in some way.</li>
-</ul>
-
-<p>To mask a phone number:</p>
-
-<ul>
-	<li>Remove all <strong>separation characters</strong>.</li>
-	<li>The masked phone number should have the form:
-	<ul>
-		<li><code>&quot;***-***-XXXX&quot;</code> if the country code has 0 digits.</li>
-		<li><code>&quot;+*-***-***-XXXX&quot;</code> if the country code has 1 digit.</li>
-		<li><code>&quot;+**-***-***-XXXX&quot;</code> if the country code has 2 digits.</li>
-		<li><code>&quot;+***-***-***-XXXX&quot;</code> if the country code has 3 digits.</li>
-	</ul>
-	</li>
-	<li><code>&quot;XXXX&quot;</code> is the last 4 digits of the <strong>local number</strong>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;LeetCode@LeetCode.com&quot;
-<strong>Output:</strong> &quot;l*****e@leetcode.com&quot;
-<strong>Explanation:</strong> s is an email address.
-The name and domain are converted to lowercase, and the middle of the name is replaced by 5 asterisks.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;AB@qq.com&quot;
-<strong>Output:</strong> &quot;a*****b@qq.com&quot;
-<strong>Explanation:</strong> s is an email address.
-The name and domain are converted to lowercase, and the middle of the name is replaced by 5 asterisks.
-Note that even though &quot;ab&quot; is 2 characters, it still must have 5 asterisks in the middle.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1(234)567-890&quot;
-<strong>Output:</strong> &quot;***-***-7890&quot;
-<strong>Explanation:</strong> s is a phone number.
-There are 10 digits, so the local number is 10 digits and the country code is 0 digits.
-Thus, the resulting masked number is &quot;***-***-7890&quot;.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;86-(10)12345678&quot;
-<strong>Output:</strong> &quot;+**-***-***-5678&quot;
-<strong>Explanation:</strong> s is a phone number.
-There are 12 digits, so the local number is 10 digits and the country code is 2 digits.
-Thus, the resulting masked number is &quot;+**-***-***-7890&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>s</code> is either a <strong>valid</strong>&nbsp;email or a phone number.</li>
-	<li>If <code>s</code> is an email:
-	<ul>
-		<li><code>8 &lt;= s.length &lt;= 40</code></li>
-		<li><code>s</code>&nbsp;consists of uppercase and lowercase English letters and exactly one <code>&#39;@&#39;</code>&nbsp;symbol and&nbsp;<code>&#39;.&#39;</code>&nbsp;symbol.</li>
-	</ul>
-	</li>
-	<li>If <code>s</code> is a phone number:
-	<ul>
-		<li><code>10 &lt;= s.length &lt;= 20</code></li>
-		<li><code>s</code>&nbsp;consists of digits, spaces, and the symbols&nbsp;<code>&#39;(&#39;</code>,&nbsp;<code>&#39;)&#39;</code>,&nbsp;<code>&#39;-&#39;</code>, and&nbsp;<code>&#39;+&#39;</code>.</li>
-	</ul>
-	</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/masking-personal-information/masking_personal_information.go b/problems/masking-personal-information/masking_personal_information.go
deleted file mode 100644
index 1929e63bc..000000000
--- a/problems/masking-personal-information/masking_personal_information.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem831
diff --git a/problems/masking-personal-information/masking_personal_information_test.go b/problems/masking-personal-information/masking_personal_information_test.go
deleted file mode 100644
index 1929e63bc..000000000
--- a/problems/masking-personal-information/masking_personal_information_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem831
diff --git a/problems/matchsticks-to-square/README.md b/problems/matchsticks-to-square/README.md
deleted file mode 100644
index 2b7ec49a7..000000000
--- a/problems/matchsticks-to-square/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../concatenated-words "Concatenated Words")
-　　　　　　　　　　　　　　　　
-[Next >](../ones-and-zeroes "Ones and Zeroes")
-
-## [473. Matchsticks to Square (Medium)](https://leetcode.com/problems/matchsticks-to-square "火柴拼正方形")
-
-<p>You are given an integer array <code>matchsticks</code> where <code>matchsticks[i]</code> is the length of the <code>i<sup>th</sup></code> matchstick. You want to use <strong>all the matchsticks</strong> to make one square. You <strong>should not break</strong> any stick, but you can link them up, and each matchstick must be used <strong>exactly one time</strong>.</p>
-
-<p>Return <code>true</code> if you can make this square and <code>false</code> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/09/matchsticks1-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> matchsticks = [1,1,2,2,2]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You can form a square with length 2, one side of the square came two sticks with length 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matchsticks = [3,3,3,3,4]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> You cannot find a way to form a square with all the matchsticks.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= matchsticks.length &lt;= 15</code></li>
-	<li><code>1 &lt;= matchsticks[i] &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Treat the matchsticks as an array. Can we split the array into 4 equal halves?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Every matchstick can belong to either of the 4 sides. We don't know which one. Maybe try out all options!
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For every matchstick, we have to try out each of the 4 options i.e. which side it can belong to. We can make use of recursion for this.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-We don't really need to keep track of which matchsticks belong to a particular side during recursion. We just need to keep track of the <b>length</b> of each of the 4 sides.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-When all matchsticks have been used we simply need to see the length of all 4 sides. If they're equal, we have a square on our hands!
-</details>
diff --git a/problems/matchsticks-to-square/matchsticks_to_square.go b/problems/matchsticks-to-square/matchsticks_to_square.go
deleted file mode 100644
index f5b5fb253..000000000
--- a/problems/matchsticks-to-square/matchsticks_to_square.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem473
diff --git a/problems/matchsticks-to-square/matchsticks_to_square_test.go b/problems/matchsticks-to-square/matchsticks_to_square_test.go
deleted file mode 100644
index f5b5fb253..000000000
--- a/problems/matchsticks-to-square/matchsticks_to_square_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem473
diff --git a/problems/matrix-block-sum/README.md b/problems/matrix-block-sum/README.md
deleted file mode 100644
index 9fe7fe48f..000000000
--- a/problems/matrix-block-sum/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decompress-run-length-encoded-list "Decompress Run-Length Encoded List")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-nodes-with-even-valued-grandparent "Sum of Nodes with Even-Valued Grandparent")
-
-## [1314. Matrix Block Sum (Medium)](https://leetcode.com/problems/matrix-block-sum "矩阵区域和")
-
-<p>Given a <code>m x n</code> matrix <code>mat</code> and an integer <code>k</code>, return <em>a matrix</em> <code>answer</code> <em>where each</em> <code>answer[i][j]</code> <em>is the sum of all elements</em> <code>mat[r][c]</code> <em>for</em>:</p>
-
-<ul>
-	<li><code>i - k &lt;= r &lt;= i + k,</code></li>
-	<li><code>j - k &lt;= c &lt;= j + k</code>, and</li>
-	<li><code>(r, c)</code> is a valid position in the matrix.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[1,2,3],[4,5,6],[7,8,9]], k = 1
-<strong>Output:</strong> [[12,21,16],[27,45,33],[24,39,28]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[1,2,3],[4,5,6],[7,8,9]], k = 2
-<strong>Output:</strong> [[45,45,45],[45,45,45],[45,45,45]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m ==&nbsp;mat.length</code></li>
-	<li><code>n ==&nbsp;mat[i].length</code></li>
-	<li><code>1 &lt;= m, n, k &lt;= 100</code></li>
-	<li><code>1 &lt;= mat[i][j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Stamping the Grid](../stamping-the-grid) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to calculate the required sum for a cell (i,j) fast ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the concept of cumulative sum array.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Create a cumulative sum matrix where dp[i][j] is the sum of all cells in the rectangle from (0,0) to (i,j), use inclusion-exclusion idea.
-</details>
diff --git a/problems/matrix-cells-in-distance-order/README.md b/problems/matrix-cells-in-distance-order/README.md
deleted file mode 100644
index 9fa55ff71..000000000
--- a/problems/matrix-cells-in-distance-order/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-city-scheduling "Two City Scheduling")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-sum-of-two-non-overlapping-subarrays "Maximum Sum of Two Non-Overlapping Subarrays")
-
-## [1030. Matrix Cells in Distance Order (Easy)](https://leetcode.com/problems/matrix-cells-in-distance-order "距离顺序排列矩阵单元格")
-
-<p>You are given four integers <code>row</code>, <code>cols</code>, <code>rCenter</code>, and <code>cCenter</code>. There is a <code>rows x cols</code> matrix and you are on the cell with the coordinates <code>(rCenter, cCenter)</code>.</p>
-
-<p>Return <em>the coordinates of all cells in the matrix, sorted by their <strong>distance</strong> from </em><code>(rCenter, cCenter)</code><em> from the smallest distance to the largest distance</em>. You may return the answer in <strong>any order</strong> that satisfies this condition.</p>
-
-<p>The <strong>distance</strong> between two cells <code>(r<sub>1</sub>, c<sub>1</sub>)</code> and <code>(r<sub>2</sub>, c<sub>2</sub>)</code> is <code>|r<sub>1</sub> - r<sub>2</sub>| + |c<sub>1</sub> - c<sub>2</sub>|</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rows = 1, cols = 2, rCenter = 0, cCenter = 0
-<strong>Output:</strong> [[0,0],[0,1]]
-<strong>Explanation:</strong> The distances from (0, 0) to other cells are: [0,1]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rows = 2, cols = 2, rCenter = 0, cCenter = 1
-<strong>Output:</strong> [[0,1],[0,0],[1,1],[1,0]]
-<strong>Explanation:</strong> The distances from (0, 1) to other cells are: [0,1,1,2]
-The answer [[0,1],[1,1],[0,0],[1,0]] would also be accepted as correct.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> rows = 2, cols = 3, rCenter = 1, cCenter = 2
-<strong>Output:</strong> [[1,2],[0,2],[1,1],[0,1],[1,0],[0,0]]
-<strong>Explanation:</strong> The distances from (1, 2) to other cells are: [0,1,1,2,2,3]
-There are other answers that would also be accepted as correct, such as [[1,2],[1,1],[0,2],[1,0],[0,1],[0,0]].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rows, cols &lt;= 100</code></li>
-	<li><code>0 &lt;= rCenter &lt; rows</code></li>
-	<li><code>0 &lt;= cCenter &lt; cols</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/matrix-cells-in-distance-order/matrix_cells_in_distance_order.go b/problems/matrix-cells-in-distance-order/matrix_cells_in_distance_order.go
deleted file mode 100644
index 02046c07f..000000000
--- a/problems/matrix-cells-in-distance-order/matrix_cells_in_distance_order.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package problem1030
-
-var res = [10000][]int{}
-
-func allCellsDistOrder(R int, C int, r0 int, c0 int) [][]int {
-	dist := [200][][]int{}
-	for r := 0; r < R; r++ {
-		for c := 0; c < C; c++ {
-			d := abs(r-r0) + abs(c-c0)
-			dist[d] = append(dist[d], []int{r, c})
-		}
-	}
-	begin, end := 0, 0
-	for d := 0; len(dist[d]) > 0; d++ {
-		begin, end = end, end+len(dist[d])
-		copy(res[begin:end], dist[d])
-	}
-	return res[:end]
-}
-
-func abs(n int) int {
-	if n < 0 {
-		return -n
-	}
-	return n
-}
diff --git a/problems/matrix-diagonal-sum/README.md b/problems/matrix-diagonal-sum/README.md
deleted file mode 100644
index ea3934e05..000000000
--- a/problems/matrix-diagonal-sum/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../warehouse-manager "Warehouse Manager")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-split-a-string "Number of Ways to Split a String")
-
-## [1572. Matrix Diagonal Sum (Easy)](https://leetcode.com/problems/matrix-diagonal-sum "矩阵对角线元素的和")
-
-<p>Given a&nbsp;square&nbsp;matrix&nbsp;<code>mat</code>, return the sum of the matrix diagonals.</p>
-
-<p>Only include the sum of all the elements on the primary diagonal and all the elements on the secondary diagonal that are not part of the primary diagonal.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/14/sample_1911.png" style="width: 336px; height: 174px;" />
-<pre>
-<strong>Input:</strong> mat = [[<strong>1</strong>,2,<strong>3</strong>],
-&nbsp;             [4,<strong>5</strong>,6],
-&nbsp;             [<strong>7</strong>,8,<strong>9</strong>]]
-<strong>Output:</strong> 25
-<strong>Explanation: </strong>Diagonals sum: 1 + 5 + 9 + 3 + 7 = 25
-Notice that element mat[1][1] = 5 is counted only once.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[<strong>1</strong>,1,1,<strong>1</strong>],
-&nbsp;             [1,<strong>1</strong>,<strong>1</strong>,1],
-&nbsp;             [1,<strong>1</strong>,<strong>1</strong>,1],
-&nbsp;             [<strong>1</strong>,1,1,<strong>1</strong>]]
-<strong>Output:</strong> 8
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[<strong>5</strong>]]
-<strong>Output:</strong> 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == mat.length == mat[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= mat[i][j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Check if Every Row and Column Contains All Numbers](../check-if-every-row-and-column-contains-all-numbers) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There will be overlap of elements in the primary and secondary diagonals if and only if the length of the matrix is odd, which is at the center.
-</details>
diff --git a/problems/max-area-of-island/README.md b/problems/max-area-of-island/README.md
deleted file mode 100644
index 670981ff1..000000000
--- a/problems/max-area-of-island/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-distinct-islands "Number of Distinct Islands")
-　　　　　　　　　　　　　　　　
-[Next >](../count-binary-substrings "Count Binary Substrings")
-
-## [695. Max Area of Island (Medium)](https://leetcode.com/problems/max-area-of-island "岛屿的最大面积")
-
-<p>You are given an <code>m x n</code> binary matrix <code>grid</code>. An island is a group of <code>1</code>&#39;s (representing land) connected <strong>4-directionally</strong> (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.</p>
-
-<p>The <strong>area</strong> of an island is the number of cells with a value <code>1</code> in the island.</p>
-
-<p>Return <em>the maximum <strong>area</strong> of an island in </em><code>grid</code>. If there is no island, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/01/maxarea1-grid.jpg" style="width: 500px; height: 310px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,0,1,0,0,0,0,1,0,0,0,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,1,1,0,1,0,0,0,0,0,0,0,0],[0,1,0,0,1,1,0,0,1,0,1,0,0],[0,1,0,0,1,1,0,0,1,1,1,0,0],[0,0,0,0,0,0,0,0,0,0,1,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,0,0,0,0,0,0,1,1,0,0,0,0]]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The answer is not 11, because the island must be connected 4-directionally.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0,0,0,0,0,0,0,0]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Number of Islands](../number-of-islands) (Medium)
-  1. [Island Perimeter](../island-perimeter) (Easy)
-  1. [Largest Submatrix With Rearrangements](../largest-submatrix-with-rearrangements) (Medium)
diff --git a/problems/max-area-of-island/max_area_of_island.go b/problems/max-area-of-island/max_area_of_island.go
deleted file mode 100644
index 57d0f0002..000000000
--- a/problems/max-area-of-island/max_area_of_island.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem695
diff --git a/problems/max-area-of-island/max_area_of_island_test.go b/problems/max-area-of-island/max_area_of_island_test.go
deleted file mode 100644
index 57d0f0002..000000000
--- a/problems/max-area-of-island/max_area_of_island_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem695
diff --git a/problems/max-chunks-to-make-sorted-ii/README.md b/problems/max-chunks-to-make-sorted-ii/README.md
deleted file mode 100644
index c0c9f7075..000000000
--- a/problems/max-chunks-to-make-sorted-ii/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reorganize-string "Reorganize String")
-　　　　　　　　　　　　　　　　
-[Next >](../max-chunks-to-make-sorted "Max Chunks To Make Sorted")
-
-## [768. Max Chunks To Make Sorted II (Hard)](https://leetcode.com/problems/max-chunks-to-make-sorted-ii "最多能完成排序的块 II")
-
-<p>You are given an integer array <code>arr</code>.</p>
-
-<p>We split <code>arr</code> into some number of <strong>chunks</strong> (i.e., partitions), and individually sort each chunk. After concatenating them, the result should equal the sorted array.</p>
-
-<p>Return <em>the largest number of chunks we can make to sort the array</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [5,4,3,2,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-Splitting into two or more chunks will not return the required result.
-For example, splitting into [5, 4], [3, 2, 1] will result in [4, 5, 1, 2, 3], which isn&#39;t sorted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,1,3,4,4]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-We can split into two chunks, such as [2, 1], [3, 4, 4].
-However, splitting into [2, 1], [3], [4], [4] is the highest number of chunks possible.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 2000</code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Max Chunks To Make Sorted](../max-chunks-to-make-sorted) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Each k for which some permutation of arr[:k] is equal to sorted(arr)[:k] is where we should cut each chunk.
-</details>
diff --git a/problems/max-chunks-to-make-sorted-ii/max_chunks_to_make_sorted_ii.go b/problems/max-chunks-to-make-sorted-ii/max_chunks_to_make_sorted_ii.go
deleted file mode 100644
index 0b9379bb2..000000000
--- a/problems/max-chunks-to-make-sorted-ii/max_chunks_to_make_sorted_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem768
diff --git a/problems/max-chunks-to-make-sorted-ii/max_chunks_to_make_sorted_ii_test.go b/problems/max-chunks-to-make-sorted-ii/max_chunks_to_make_sorted_ii_test.go
deleted file mode 100644
index 0b9379bb2..000000000
--- a/problems/max-chunks-to-make-sorted-ii/max_chunks_to_make_sorted_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem768
diff --git a/problems/max-chunks-to-make-sorted/README.md b/problems/max-chunks-to-make-sorted/README.md
deleted file mode 100644
index f5bbcec5d..000000000
--- a/problems/max-chunks-to-make-sorted/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-chunks-to-make-sorted-ii "Max Chunks To Make Sorted II")
-　　　　　　　　　　　　　　　　
-[Next >](../basic-calculator-iv "Basic Calculator IV")
-
-## [769. Max Chunks To Make Sorted (Medium)](https://leetcode.com/problems/max-chunks-to-make-sorted "最多能完成排序的块")
-
-<p>You are given an integer array <code>arr</code> of length <code>n</code> that represents a permutation of the integers in the range <code>[0, n - 1]</code>.</p>
-
-<p>We split <code>arr</code> into some number of <strong>chunks</strong> (i.e., partitions), and individually sort each chunk. After concatenating them, the result should equal the sorted array.</p>
-
-<p>Return <em>the largest number of chunks we can make to sort the array</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,3,2,1,0]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-Splitting into two or more chunks will not return the required result.
-For example, splitting into [4, 3], [2, 1, 0] will result in [3, 4, 0, 1, 2], which isn&#39;t sorted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,0,2,3,4]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-We can split into two chunks, such as [1, 0], [2, 3, 4].
-However, splitting into [1, 0], [2], [3], [4] is the highest number of chunks possible.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == arr.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10</code></li>
-	<li><code>0 &lt;= arr[i] &lt; n</code></li>
-	<li>All the elements of <code>arr</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Max Chunks To Make Sorted II](../max-chunks-to-make-sorted-ii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The first chunk can be found as the smallest k for which A[:k+1] == [0, 1, 2, ...k]; then we repeat this process.
-</details>
diff --git a/problems/max-chunks-to-make-sorted/max_chunks_to_make_sorted.go b/problems/max-chunks-to-make-sorted/max_chunks_to_make_sorted.go
deleted file mode 100644
index c73d14383..000000000
--- a/problems/max-chunks-to-make-sorted/max_chunks_to_make_sorted.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem769
diff --git a/problems/max-chunks-to-make-sorted/max_chunks_to_make_sorted_test.go b/problems/max-chunks-to-make-sorted/max_chunks_to_make_sorted_test.go
deleted file mode 100644
index c73d14383..000000000
--- a/problems/max-chunks-to-make-sorted/max_chunks_to_make_sorted_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem769
diff --git a/problems/max-consecutive-ones-ii/README.md b/problems/max-consecutive-ones-ii/README.md
deleted file mode 100644
index 6c28cd7d7..000000000
--- a/problems/max-consecutive-ones-ii/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../predict-the-winner "Predict the Winner")
-　　　　　　　　　　　　　　　　
-[Next >](../zuma-game "Zuma Game")
-
-## [487. Max Consecutive Ones II (Medium)](https://leetcode.com/problems/max-consecutive-ones-ii "最大连续1的个数 II")
-
-<p>
-Given a binary array, find the maximum number of consecutive 1s in this array if you can flip at most one 0.
-</p>
-
-<p><b>Example 1:</b><br />
-<pre>
-<b>Input:</b> [1,0,1,1,0]
-<b>Output:</b> 4
-<b>Explanation:</b> Flip the first zero will get the the maximum number of consecutive 1s.
-    After flipping, the maximum number of consecutive 1s is 4.
-</pre>
-</p>
-
-<p><b>Note:</b>
-<ul>
-<li>The input array will only contain <code>0</code> and <code>1</code>.</li>
-<li>The length of input array is a positive integer and will not exceed 10,000</li>
-</ul>
-</p>
-
-<p><b>Follow up:</b><br />
-What if the input numbers come in one by one as an <b>infinite stream</b>? In other words, you can't store all numbers coming from the stream as it's too large to hold in memory. Could you solve it efficiently?
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Max Consecutive Ones](../max-consecutive-ones) (Easy)
-  1. [Max Consecutive Ones III](../max-consecutive-ones-iii) (Medium)
diff --git a/problems/max-consecutive-ones-ii/max_consecutive_ones_ii.go b/problems/max-consecutive-ones-ii/max_consecutive_ones_ii.go
deleted file mode 100644
index b0097ae9e..000000000
--- a/problems/max-consecutive-ones-ii/max_consecutive_ones_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem487
diff --git a/problems/max-consecutive-ones-ii/max_consecutive_ones_ii_test.go b/problems/max-consecutive-ones-ii/max_consecutive_ones_ii_test.go
deleted file mode 100644
index b0097ae9e..000000000
--- a/problems/max-consecutive-ones-ii/max_consecutive_ones_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem487
diff --git a/problems/max-consecutive-ones-iii/README.md b/problems/max-consecutive-ones-iii/README.md
deleted file mode 100644
index 2d8260401..000000000
--- a/problems/max-consecutive-ones-iii/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-word-is-valid-after-substitutions "Check If Word Is Valid After Substitutions")
-　　　　　　　　　　　　　　　　
-[Next >](../maximize-sum-of-array-after-k-negations "Maximize Sum Of Array After K Negations")
-
-## [1004. Max Consecutive Ones III (Medium)](https://leetcode.com/problems/max-consecutive-ones-iii "最大连续1的个数 III")
-
-<p>Given a binary array <code>nums</code> and an integer <code>k</code>, return <em>the maximum number of consecutive </em><code>1</code><em>&#39;s in the array if you can flip at most</em> <code>k</code> <code>0</code>&#39;s.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,0,0,0,1,1,1,1,0], k = 2
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> [1,1,1,0,0,<u><strong>1</strong>,1,1,1,1,<strong>1</strong></u>]
-Bolded numbers were flipped from 0 to 1. The longest subarray is underlined.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,1,1,0,0,1,1,1,0,1,1,0,0,0,1,1,1,1], k = 3
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> [0,0,<u>1,1,<strong>1</strong>,<strong>1</strong>,1,1,1,<strong>1</strong>,1,1</u>,0,0,0,1,1,1,1]
-Bolded numbers were flipped from 0 to 1. The longest subarray is underlined.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums[i]</code> is either <code>0</code> or <code>1</code>.</li>
-	<li><code>0 &lt;= k &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Longest Substring with At Most K Distinct Characters](../longest-substring-with-at-most-k-distinct-characters) (Medium)
-  1. [Longest Repeating Character Replacement](../longest-repeating-character-replacement) (Medium)
-  1. [Max Consecutive Ones](../max-consecutive-ones) (Easy)
-  1. [Max Consecutive Ones II](../max-consecutive-ones-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-One thing's for sure, we will only flip a zero if it extends an existing window of 1s. Otherwise, there's no point in doing it, right? Think Sliding Window!
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Since we know this problem can be solved using the sliding window construct, we might as well focus in that direction for hints. Basically, in a given window, we can never have > K zeros, right?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We don't have a fixed size window in this case. The window size can grow and shrink depending upon the number of zeros we have (we don't actually have to flip the zeros here!).
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The way to shrink or expand a window would be based on the number of zeros that can still be flipped and so on.
-</details>
diff --git a/problems/max-consecutive-ones-iii/max_consecutive_ones_iii.go b/problems/max-consecutive-ones-iii/max_consecutive_ones_iii.go
deleted file mode 100644
index 9e756c14a..000000000
--- a/problems/max-consecutive-ones-iii/max_consecutive_ones_iii.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem1004
-
-func longestOnes(A []int, K int) int {
-	left, right := 0, 0
-	for right = range A {
-		K -= 1 ^ A[right] // 每次遇到 0 就会消耗一次 K
-		if K < 0 {        // K 不够用的时候，就从左边回血
-			K += 1 ^ A[left]
-			left++
-		}
-	}
-	// A[left:right+1] 并不是真的 max-length-sliding-windows
-	// 把 right-left+1 当作是 A[:right+1] 中出现过的最长子数组的长度，更合适
-	return right - left + 1
-}
diff --git a/problems/max-consecutive-ones/README.md b/problems/max-consecutive-ones/README.md
deleted file mode 100644
index 9ac8a9976..000000000
--- a/problems/max-consecutive-ones/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-permutation "Find Permutation")
-　　　　　　　　　　　　　　　　
-[Next >](../predict-the-winner "Predict the Winner")
-
-## [485. Max Consecutive Ones (Easy)](https://leetcode.com/problems/max-consecutive-ones "最大连续 1 的个数")
-
-<p>Given a binary array <code>nums</code>, return <em>the maximum number of consecutive </em><code>1</code><em>&#39;s in the array</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,0,1,1,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The first two digits or the last three digits are consecutive 1s. The maximum number of consecutive 1s is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,0,1,1,0,1]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums[i]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Max Consecutive Ones II](../max-consecutive-ones-ii) (Medium)
-  1. [Max Consecutive Ones III](../max-consecutive-ones-iii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You need to think about two things as far as any window is concerned. One is the starting point for the window. How do you detect that a new window of 1s has started? The next part is detecting the ending point for this window.
-
-How do you detect the ending point for an existing window? If you figure these two things out, you will be able to detect the windows of consecutive ones. All that remains afterward is to find the longest such window and return the size.
-</details>
diff --git a/problems/max-consecutive-ones/max_consecutive_ones.go b/problems/max-consecutive-ones/max_consecutive_ones.go
deleted file mode 100644
index 9f9419761..000000000
--- a/problems/max-consecutive-ones/max_consecutive_ones.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem485
-
-func findMaxConsecutiveOnes(nums []int) int {
-	ans, count := 0, 0
-	for _, v := range nums {
-		if v == 1 {
-			count++
-			if count > ans {
-				ans = count
-			}
-		} else {
-			count = 0
-		}
-	}
-	return ans
-}
diff --git a/problems/max-consecutive-ones/max_consecutive_ones_test.go b/problems/max-consecutive-ones/max_consecutive_ones_test.go
deleted file mode 100644
index ef665ebe0..000000000
--- a/problems/max-consecutive-ones/max_consecutive_ones_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem485
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestFindMaxConsecutiveOnes(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 1, 0, 1, 1, 1},
-			want: 3,
-		},
-		{
-			in:   []int{1, 0, 1, 1, 0, 1},
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := findMaxConsecutiveOnes(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/max-difference-you-can-get-from-changing-an-integer/README.md b/problems/max-difference-you-can-get-from-changing-an-integer/README.md
deleted file mode 100644
index 1643c22e9..000000000
--- a/problems/max-difference-you-can-get-from-changing-an-integer/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kids-with-the-greatest-number-of-candies "Kids With the Greatest Number of Candies")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-a-string-can-break-another-string "Check If a String Can Break Another String")
-
-## [1432. Max Difference You Can Get From Changing an Integer (Medium)](https://leetcode.com/problems/max-difference-you-can-get-from-changing-an-integer "改变一个整数能得到的最大差值")
-
-<p>You are given an integer <code>num</code>. You will apply the following steps exactly <strong>two</strong> times:</p>
-
-<ul>
-	<li>Pick a digit <code>x (0&nbsp;&lt;= x &lt;= 9)</code>.</li>
-	<li>Pick another digit <code>y (0&nbsp;&lt;= y &lt;= 9)</code>. The digit <code>y</code> can be equal to <code>x</code>.</li>
-	<li>Replace all the occurrences of <code>x</code> in the decimal representation of <code>num</code> by <code>y</code>.</li>
-	<li>The new integer <strong>cannot</strong> have any leading zeros, also the new integer <strong>cannot</strong> be 0.</li>
-</ul>
-
-<p>Let <code>a</code>&nbsp;and <code>b</code>&nbsp;be the results of applying the operations to <code>num</code> the first and second times, respectively.</p>
-
-<p>Return <em>the max difference</em> between <code>a</code> and <code>b</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 555
-<strong>Output:</strong> 888
-<strong>Explanation:</strong> The first time pick x = 5 and y = 9 and store the new integer in a.
-The second time pick x = 5 and y = 1 and store the new integer in b.
-We have now a = 999 and b = 111 and max difference = 888
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 9
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> The first time pick x = 9 and y = 9 and store the new integer in a.
-The second time pick x = 9 and y = 1 and store the new integer in b.
-We have now a = 9 and b = 1 and max difference = 8
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 123456
-<strong>Output:</strong> 820000
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 10000
-<strong>Output:</strong> 80000
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 9288
-<strong>Output:</strong> 8700
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num &lt;= 10^8</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We need to get the max and min value after changing num and the answer is max - min.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use brute force, try all possible changes and keep the minimum and maximum values.
-</details>
diff --git a/problems/max-dot-product-of-two-subsequences/README.md b/problems/max-dot-product-of-two-subsequences/README.md
deleted file mode 100644
index 87cfbc3c3..000000000
--- a/problems/max-dot-product-of-two-subsequences/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pseudo-palindromic-paths-in-a-binary-tree "Pseudo-Palindromic Paths in a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../rectangles-area "Rectangles Area")
-
-## [1458. Max Dot Product of Two Subsequences (Hard)](https://leetcode.com/problems/max-dot-product-of-two-subsequences "两个子序列的最大点积")
-
-<p>Given two arrays <code>nums1</code>&nbsp;and <code><font face="monospace">nums2</font></code><font face="monospace">.</font></p>
-
-<p>Return the maximum dot product&nbsp;between&nbsp;<strong>non-empty</strong> subsequences of nums1 and nums2 with the same length.</p>
-
-<p>A subsequence of a array is a new array which is formed from the original array by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (ie,&nbsp;<code>[2,3,5]</code>&nbsp;is a subsequence of&nbsp;<code>[1,2,3,4,5]</code>&nbsp;while <code>[1,5,3]</code>&nbsp;is not).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [2,1,-2,5], nums2 = [3,0,-6]
-<strong>Output:</strong> 18
-<strong>Explanation:</strong> Take subsequence [2,-2] from nums1 and subsequence [3,-6] from nums2.
-Their dot product is (2*3 + (-2)*(-6)) = 18.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [3,-2], nums2 = [2,-6,7]
-<strong>Output:</strong> 21
-<strong>Explanation:</strong> Take subsequence [3] from nums1 and subsequence [7] from nums2.
-Their dot product is (3*7) = 21.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [-1,-1], nums2 = [1,1]
-<strong>Output:</strong> -1
-<strong>Explanation: </strong>Take subsequence [-1] from nums1 and subsequence [1] from nums2.
-Their dot product is -1.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 500</code></li>
-	<li><code>-1000 &lt;= nums1[i], nums2[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming, define DP[i][j] as the maximum dot product of two subsequences starting in the position i of nums1 and position j of nums2.
-</details>
diff --git a/problems/max-increase-to-keep-city-skyline/README.md b/problems/max-increase-to-keep-city-skyline/README.md
deleted file mode 100644
index 272f8486a..000000000
--- a/problems/max-increase-to-keep-city-skyline/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-lines-to-write-string "Number of Lines To Write String")
-　　　　　　　　　　　　　　　　
-[Next >](../soup-servings "Soup Servings")
-
-## [807. Max Increase to Keep City Skyline (Medium)](https://leetcode.com/problems/max-increase-to-keep-city-skyline "保持城市天际线")
-
-<p>There is a city composed of <code>n x n</code> blocks, where each block contains a single building shaped like a vertical square prism. You are given a <strong>0-indexed</strong> <code>n x n</code> integer matrix <code>grid</code> where <code>grid[r][c]</code> represents the <strong>height</strong> of the building located in the block at row <code>r</code> and column <code>c</code>.</p>
-
-<p>A city&#39;s <strong>skyline</strong> is the the outer contour formed by all the building when viewing the side of the city from a distance. The <strong>skyline</strong> from each cardinal direction north, east, south, and west may be different.</p>
-
-<p>We are allowed to increase the height of <strong>any number of buildings by any amount</strong> (the amount can be different per building). The height of a <code>0</code>-height building can also be increased. However, increasing the height of a building should <strong>not</strong> affect the city&#39;s <strong>skyline</strong> from any cardinal direction.</p>
-
-<p>Return <em>the <strong>maximum total sum</strong> that the height of the buildings can be increased by <strong>without</strong> changing the city&#39;s <strong>skyline</strong> from any cardinal direction</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/21/807-ex1.png" style="width: 700px; height: 603px;" />
-<pre>
-<strong>Input:</strong> grid = [[3,0,8,4],[2,4,5,7],[9,2,6,3],[0,3,1,0]]
-<strong>Output:</strong> 35
-<strong>Explanation:</strong> The building heights are shown in the center of the above image.
-The skylines when viewed from each cardinal direction are drawn in red.
-The grid after increasing the height of buildings without affecting skylines is:
-gridNew = [ [8, 4, 8, 7],
-            [7, 4, 7, 7],
-            [9, 4, 8, 7],
-            [3, 3, 3, 3] ]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0,0,0],[0,0,0],[0,0,0]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Increasing the height of any building will result in the skyline changing.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length</code></li>
-	<li><code>n == grid[r].length</code></li>
-	<li><code>2 &lt;= n &lt;= 50</code></li>
-	<li><code>0 &lt;= grid[r][c] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/max-increase-to-keep-city-skyline/max_increase_to_keep_city_skyline.go b/problems/max-increase-to-keep-city-skyline/max_increase_to_keep_city_skyline.go
deleted file mode 100644
index 82b2e7c57..000000000
--- a/problems/max-increase-to-keep-city-skyline/max_increase_to_keep_city_skyline.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem807
diff --git a/problems/max-increase-to-keep-city-skyline/max_increase_to_keep_city_skyline_test.go b/problems/max-increase-to-keep-city-skyline/max_increase_to_keep_city_skyline_test.go
deleted file mode 100644
index 82b2e7c57..000000000
--- a/problems/max-increase-to-keep-city-skyline/max_increase_to_keep_city_skyline_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem807
diff --git a/problems/max-number-of-k-sum-pairs/README.md b/problems/max-number-of-k-sum-pairs/README.md
deleted file mode 100644
index 3fbe61087..000000000
--- a/problems/max-number-of-k-sum-pairs/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../goal-parser-interpretation "Goal Parser Interpretation")
-　　　　　　　　　　　　　　　　
-[Next >](../concatenation-of-consecutive-binary-numbers "Concatenation of Consecutive Binary Numbers")
-
-## [1679. Max Number of K-Sum Pairs (Medium)](https://leetcode.com/problems/max-number-of-k-sum-pairs "K 和数对的最大数目")
-
-<p>You are given an integer array <code>nums</code> and an integer <code>k</code>.</p>
-
-<p>In one operation, you can pick two numbers from the array whose sum equals <code>k</code> and remove them from the array.</p>
-
-<p>Return <em>the maximum number of operations you can perform on the array</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4], k = 5
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Starting with nums = [1,2,3,4]:
-- Remove numbers 1 and 4, then nums = [2,3]
-- Remove numbers 2 and 3, then nums = []
-There are no more pairs that sum up to 5, hence a total of 2 operations.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,3,4,3], k = 6
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Starting with nums = [3,1,3,4,3]:
-- Remove the first two 3&#39;s, then nums = [1,4,3]
-There are no more pairs that sum up to 6, hence a total of 1 operation.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The abstract problem asks to count the number of disjoint pairs with a given sum k.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each possible value x, it can be paired up with k - x.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The number of such pairs equals to  min(count(x), count(k-x)), unless that x = k / 2, where the number of such pairs will be floor(count(x) / 2).
-</details>
diff --git a/problems/max-points-on-a-line/README.md b/problems/max-points-on-a-line/README.md
deleted file mode 100644
index 30d9071b2..000000000
--- a/problems/max-points-on-a-line/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-list "Sort List")
-　　　　　　　　　　　　　　　　
-[Next >](../evaluate-reverse-polish-notation "Evaluate Reverse Polish Notation")
-
-## [149. Max Points on a Line (Hard)](https://leetcode.com/problems/max-points-on-a-line "直线上最多的点数")
-
-<p>Given an array of <code>points</code> where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> represents a point on the <strong>X-Y</strong> plane, return <em>the maximum number of points that lie on the same straight line</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/25/plane1.jpg" style="width: 300px; height: 294px;" />
-<pre>
-<strong>Input:</strong> points = [[1,1],[2,2],[3,3]]
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/25/plane2.jpg" style="width: 300px; height: 294px;" />
-<pre>
-<strong>Input:</strong> points = [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= points.length &lt;= 300</code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>-10<sup>4</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li>All the <code>points</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-
-### Similar Questions
-  1. [Line Reflection](../line-reflection) (Medium)
diff --git a/problems/max-points-on-a-line/max_points_on_a_line.go b/problems/max-points-on-a-line/max_points_on_a_line.go
deleted file mode 100644
index 81843d87a..000000000
--- a/problems/max-points-on-a-line/max_points_on_a_line.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem149
diff --git a/problems/max-points-on-a-line/max_points_on_a_line_test.go b/problems/max-points-on-a-line/max_points_on_a_line_test.go
deleted file mode 100644
index 81843d87a..000000000
--- a/problems/max-points-on-a-line/max_points_on_a_line_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem149
diff --git a/problems/max-stack/README.md b/problems/max-stack/README.md
deleted file mode 100644
index 638b9406a..000000000
--- a/problems/max-stack/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-module "Range Module")
-　　　　　　　　　　　　　　　　
-[Next >](../1-bit-and-2-bit-characters "1-bit and 2-bit Characters")
-
-## [716. Max Stack (Easy)](https://leetcode.com/problems/max-stack "最大栈")
-
-<p>Design a max stack that supports push, pop, top, peekMax and popMax.</p>
-
-<p>
-<ol>
-<li>push(x) -- Push element x onto stack.</li>
-<li>pop() -- Remove the element on top of the stack and return it.</li>
-<li>top() -- Get the element on the top.</li>
-<li>peekMax() -- Retrieve the maximum element in the stack.</li>
-<li>popMax() -- Retrieve the maximum element in the stack, and remove it. If you find more than one maximum elements, only remove the top-most one.</li>
-</ol>
-</p>
-
-<p><b>Example 1:</b><br />
-<pre>
-MaxStack stack = new MaxStack();
-stack.push(5); 
-stack.push(1);
-stack.push(5);
-stack.top(); -> 5
-stack.popMax(); -> 5
-stack.top(); -> 1
-stack.peekMax(); -> 5
-stack.pop(); -> 1
-stack.top(); -> 5
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>-1e7 <= x <= 1e7</li>
-<li>Number of operations won't exceed 10000.</li>
-<li>The last four operations won't be called when stack is empty.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Doubly-Linked List](../../tag/doubly-linked-list/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [Min Stack](../min-stack) (Easy)
diff --git a/problems/max-stack/max_stack.go b/problems/max-stack/max_stack.go
deleted file mode 100644
index 11d92ea69..000000000
--- a/problems/max-stack/max_stack.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem716
diff --git a/problems/max-stack/max_stack_test.go b/problems/max-stack/max_stack_test.go
deleted file mode 100644
index 11d92ea69..000000000
--- a/problems/max-stack/max_stack_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem716
diff --git a/problems/max-sum-of-rectangle-no-larger-than-k/README.md b/problems/max-sum-of-rectangle-no-larger-than-k/README.md
deleted file mode 100644
index fd0a83635..000000000
--- a/problems/max-sum-of-rectangle-no-larger-than-k/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-hit-counter "Design Hit Counter")
-　　　　　　　　　　　　　　　　
-[Next >](../nested-list-weight-sum-ii "Nested List Weight Sum II")
-
-## [363. Max Sum of Rectangle No Larger Than K (Hard)](https://leetcode.com/problems/max-sum-of-rectangle-no-larger-than-k "矩形区域不超过 K 的最大数值和")
-
-<p>Given an <code>m x n</code> matrix <code>matrix</code> and an integer <code>k</code>, return <em>the max sum of a rectangle in the matrix such that its sum is no larger than</em> <code>k</code>.</p>
-
-<p>It is <strong>guaranteed</strong> that there will be a rectangle with a sum no larger than <code>k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/18/sum-grid.jpg" style="width: 255px; height: 176px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,0,1],[0,-2,3]], k = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Because the sum of the blue rectangle [[0, 1], [-2, 3]] is 2, and 2 is the max number no larger than k (k = 2).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[2,2,-1]], k = 3
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li><code>-100 &lt;= matrix[i][j] &lt;= 100</code></li>
-	<li><code>-10<sup>5</sup> &lt;= k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> What if the number of rows is much larger than the number of columns?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
diff --git a/problems/max-sum-of-rectangle-no-larger-than-k/max_sum_of_rectangle_no_larger_than_k.go b/problems/max-sum-of-rectangle-no-larger-than-k/max_sum_of_rectangle_no_larger_than_k.go
deleted file mode 100644
index 0ace882ee..000000000
--- a/problems/max-sum-of-rectangle-no-larger-than-k/max_sum_of_rectangle_no_larger_than_k.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem363
diff --git a/problems/max-sum-of-rectangle-no-larger-than-k/max_sum_of_rectangle_no_larger_than_k_test.go b/problems/max-sum-of-rectangle-no-larger-than-k/max_sum_of_rectangle_no_larger_than_k_test.go
deleted file mode 100644
index 0ace882ee..000000000
--- a/problems/max-sum-of-rectangle-no-larger-than-k/max_sum_of_rectangle_no_larger_than_k_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem363
diff --git a/problems/max-value-of-equation/README.md b/problems/max-value-of-equation/README.md
deleted file mode 100644
index 4acc64f7b..000000000
--- a/problems/max-value-of-equation/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-subsequences-that-satisfy-the-given-sum-condition "Number of Subsequences That Satisfy the Given Sum Condition")
-　　　　　　　　　　　　　　　　
-[Next >](../design-a-file-sharing-system "Design a File Sharing System")
-
-## [1499. Max Value of Equation (Hard)](https://leetcode.com/problems/max-value-of-equation "满足不等式的最大值")
-
-<p>You are given an array <code>points</code> containing the coordinates of points on a 2D plane, sorted by the x-values, where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> such that <code>x<sub>i</sub> &lt; x<sub>j</sub></code> for all <code>1 &lt;= i &lt; j &lt;= points.length</code>. You are also given an integer <code>k</code>.</p>
-
-<p>Return <em>the maximum value of the equation </em><code>y<sub>i</sub> + y<sub>j</sub> + |x<sub>i</sub> - x<sub>j</sub>|</code> where <code>|x<sub>i</sub> - x<sub>j</sub>| &lt;= k</code> and <code>1 &lt;= i &lt; j &lt;= points.length</code>.</p>
-
-<p>It is guaranteed that there exists at least one pair of points that satisfy the constraint <code>|x<sub>i</sub> - x<sub>j</sub>| &lt;= k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[1,3],[2,0],[5,10],[6,-10]], k = 1
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The first two points satisfy the condition |x<sub>i</sub> - x<sub>j</sub>| &lt;= 1 and if we calculate the equation we get 3 + 0 + |1 - 2| = 4. Third and fourth points also satisfy the condition and give a value of 10 + -10 + |5 - 6| = 1.
-No other pairs satisfy the condition, so we return the max of 4 and 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[0,0],[3,0],[9,2]], k = 3
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>Only the first two points have an absolute difference of 3 or less in the x-values, and give the value of 0 + 0 + |0 - 3| = 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= points.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>-10<sup>8</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>8</sup></code></li>
-	<li><code>0 &lt;= k &lt;= 2 * 10<sup>8</sup></code></li>
-	<li><code>x<sub>i</sub> &lt; x<sub>j</sub></code> for all <code>1 &lt;= i &lt; j &lt;= points.length</code></li>
-	<li><code>x<sub>i</sub></code> form a strictly increasing sequence.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Monotonic Queue](../../tag/monotonic-queue/README.md)]
-
-### Similar Questions
-  1. [Count Pairs in Two Arrays](../count-pairs-in-two-arrays) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a priority queue to store for each point i, the tuple [yi-xi, xi]
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop through the array and pop elements from the heap if the condition xj - xi > k, where j is the current index and i is the point on top the queue.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-After popping elements from the queue. If the queue is not empty, calculate the equation with the current point and the point on top of the queue and maximize the answer.
-</details>
diff --git a/problems/maximal-network-rank/README.md b/problems/maximal-network-rank/README.md
deleted file mode 100644
index d5630d2b3..000000000
--- a/problems/maximal-network-rank/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-nesting-depth-of-the-parentheses "Maximum Nesting Depth of the Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../split-two-strings-to-make-palindrome "Split Two Strings to Make Palindrome")
-
-## [1615. Maximal Network Rank (Medium)](https://leetcode.com/problems/maximal-network-rank "最大网络秩")
-
-<p>There is an infrastructure of <code>n</code> cities with some number of <code>roads</code> connecting these cities. Each <code>roads[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that there is a bidirectional road between cities <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code>.</p>
-
-<p>The <strong>network rank</strong><em> </em>of <strong>two different cities</strong> is defined as the total number of&nbsp;<strong>directly</strong> connected roads to <strong>either</strong> city. If a road is directly connected to both cities, it is only counted <strong>once</strong>.</p>
-
-<p>The <strong>maximal network rank </strong>of the infrastructure is the <strong>maximum network rank</strong> of all pairs of different cities.</p>
-
-<p>Given the integer <code>n</code> and the array <code>roads</code>, return <em>the <strong>maximal network rank</strong> of the entire infrastructure</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/ex1.png" style="width: 292px; height: 172px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, roads = [[0,1],[0,3],[1,2],[1,3]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The network rank of cities 0 and 1 is 4 as there are 4 roads that are connected to either 0 or 1. The road between 0 and 1 is only counted once.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/ex2.png" style="width: 292px; height: 172px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, roads = [[0,1],[0,3],[1,2],[1,3],[2,3],[2,4]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> There are 5 roads that are connected to cities 1 or 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 8, roads = [[0,1],[1,2],[2,3],[2,4],[5,6],[5,7]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The network rank of 2 and 5 is 5. Notice that all the cities do not have to be connected.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 100</code></li>
-	<li><code>0 &lt;= roads.length &lt;= n * (n - 1) / 2</code></li>
-	<li><code>roads[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub>&nbsp;&lt;= n-1</code></li>
-	<li><code>a<sub>i</sub>&nbsp;!=&nbsp;b<sub>i</sub></code></li>
-	<li>Each&nbsp;pair of cities has <strong>at most one</strong> road connecting them.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try every pair of different cities and calculate its network rank.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The network rank of two vertices is <i>almost</i> the sum of their degrees.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How can you efficiently check if there is a road connecting two different cities?
-</details>
diff --git a/problems/maximal-rectangle/README.md b/problems/maximal-rectangle/README.md
deleted file mode 100644
index 78ebdca14..000000000
--- a/problems/maximal-rectangle/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-rectangle-in-histogram "Largest Rectangle in Histogram")
-　　　　　　　　　　　　　　　　
-[Next >](../partition-list "Partition List")
-
-## [85. Maximal Rectangle (Hard)](https://leetcode.com/problems/maximal-rectangle "最大矩形")
-
-<p>Given a <code>rows x cols</code>&nbsp;binary <code>matrix</code> filled with <code>0</code>&#39;s and <code>1</code>&#39;s, find the largest rectangle containing only <code>1</code>&#39;s and return <em>its area</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/14/maximal.jpg" style="width: 402px; height: 322px;" />
-<pre>
-<strong>Input:</strong> matrix = [[&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;],[&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;]]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The maximal rectangle is shown in the above picture.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[&quot;0&quot;]]
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[&quot;1&quot;]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>rows == matrix.length</code></li>
-	<li><code>cols == matrix[i].length</code></li>
-	<li><code>1 &lt;= row, cols &lt;= 200</code></li>
-	<li><code>matrix[i][j]</code> is <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Largest Rectangle in Histogram](../largest-rectangle-in-histogram) (Hard)
-  1. [Maximal Square](../maximal-square) (Medium)
diff --git a/problems/maximal-rectangle/maximal_rectangle.go b/problems/maximal-rectangle/maximal_rectangle.go
deleted file mode 100644
index f15ee5df3..000000000
--- a/problems/maximal-rectangle/maximal_rectangle.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem85
diff --git a/problems/maximal-rectangle/maximal_rectangle_test.go b/problems/maximal-rectangle/maximal_rectangle_test.go
deleted file mode 100644
index f15ee5df3..000000000
--- a/problems/maximal-rectangle/maximal_rectangle_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem85
diff --git a/problems/maximal-square/README.md b/problems/maximal-square/README.md
deleted file mode 100644
index 354993505..000000000
--- a/problems/maximal-square/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../contains-duplicate-iii "Contains Duplicate III")
-　　　　　　　　　　　　　　　　
-[Next >](../count-complete-tree-nodes "Count Complete Tree Nodes")
-
-## [221. Maximal Square (Medium)](https://leetcode.com/problems/maximal-square "最大正方形")
-
-<p>Given an <code>m x n</code> binary <code>matrix</code> filled with <code>0</code>&#39;s and <code>1</code>&#39;s, <em>find the largest square containing only</em> <code>1</code>&#39;s <em>and return its area</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/26/max1grid.jpg" style="width: 400px; height: 319px;" />
-<pre>
-<strong>Input:</strong> matrix = [[&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;],[&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;]]
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/26/max2grid.jpg" style="width: 165px; height: 165px;" />
-<pre>
-<strong>Input:</strong> matrix = [[&quot;0&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;0&quot;]]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[&quot;0&quot;]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 300</code></li>
-	<li><code>matrix[i][j]</code> is <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Maximal Rectangle](../maximal-rectangle) (Hard)
-  1. [Largest Plus Sign](../largest-plus-sign) (Medium)
diff --git a/problems/maximal-square/maximal_square.go b/problems/maximal-square/maximal_square.go
deleted file mode 100644
index d50c314de..000000000
--- a/problems/maximal-square/maximal_square.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem221
diff --git a/problems/maximal-square/maximal_square_test.go b/problems/maximal-square/maximal_square_test.go
deleted file mode 100644
index d50c314de..000000000
--- a/problems/maximal-square/maximal_square_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem221
diff --git a/problems/maximize-distance-to-closest-person/README.md b/problems/maximize-distance-to-closest-person/README.md
deleted file mode 100644
index e998d48da..000000000
--- a/problems/maximize-distance-to-closest-person/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shifting-letters "Shifting Letters")
-　　　　　　　　　　　　　　　　
-[Next >](../rectangle-area-ii "Rectangle Area II")
-
-## [849. Maximize Distance to Closest Person (Medium)](https://leetcode.com/problems/maximize-distance-to-closest-person "到最近的人的最大距离")
-
-<p>You are given an array representing a row of <code>seats</code> where <code>seats[i] = 1</code> represents a person sitting in the <code>i<sup>th</sup></code> seat, and <code>seats[i] = 0</code> represents that the <code>i<sup>th</sup></code> seat is empty <strong>(0-indexed)</strong>.</p>
-
-<p>There is at least one empty seat, and at least one person sitting.</p>
-
-<p>Alex wants to sit in the seat such that the distance between him and the closest person to him is maximized.&nbsp;</p>
-
-<p>Return <em>that maximum distance to the closest person</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/10/distance.jpg" style="width: 650px; height: 257px;" />
-<pre>
-<strong>Input:</strong> seats = [1,0,0,0,1,0,1]
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>
-If Alex sits in the second open seat (i.e. seats[2]), then the closest person has distance 2.
-If Alex sits in any other open seat, the closest person has distance 1.
-Thus, the maximum distance to the closest person is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> seats = [1,0,0,0]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>
-If Alex sits in the last seat (i.e. seats[3]), the closest person is 3 seats away.
-This is the maximum distance possible, so the answer is 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> seats = [0,1]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= seats.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>seats[i]</code>&nbsp;is <code>0</code> or&nbsp;<code>1</code>.</li>
-	<li>At least one seat is <strong>empty</strong>.</li>
-	<li>At least one seat is <strong>occupied</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Exam Room](../exam-room) (Medium)
diff --git a/problems/maximize-distance-to-closest-person/maximize_distance_to_closest_person.go b/problems/maximize-distance-to-closest-person/maximize_distance_to_closest_person.go
deleted file mode 100644
index 6b47de984..000000000
--- a/problems/maximize-distance-to-closest-person/maximize_distance_to_closest_person.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem849
-
-func maxDistToClosest(seats []int) int {
-	ans, ec := 0, 0
-	for i, v := range seats {
-		if v == 0 {
-			ec++
-		} else if ec > 0 {
-			if i == ec { // 001
-				ans = ec
-			} else if (ec+1)/2 > ans { // 101
-				ans = (ec + 1) / 2
-			}
-			ec = 0
-		}
-	}
-	if ec > ans { // 100
-		ans = ec
-	}
-	return ans
-}
diff --git a/problems/maximize-distance-to-closest-person/maximize_distance_to_closest_person_test.go b/problems/maximize-distance-to-closest-person/maximize_distance_to_closest_person_test.go
deleted file mode 100644
index 1d5e65f7c..000000000
--- a/problems/maximize-distance-to-closest-person/maximize_distance_to_closest_person_test.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package problem849
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMaxDistToClosest(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 0, 0, 0, 1, 0, 1},
-			want: 2,
-		},
-		{
-			in:   []int{1, 0, 0, 0},
-			want: 3,
-		},
-		{
-			in:   []int{0, 0, 0, 1},
-			want: 3,
-		},
-		{
-			in:   []int{0, 0, 0, 0, 0, 1, 0},
-			want: 5,
-		},
-		{
-			in:   []int{0, 1, 0, 0, 0, 1, 0},
-			want: 2,
-		},
-		{
-			in:   []int{0, 1, 0, 0, 0, 0, 0},
-			want: 5,
-		},
-		{
-			in:   []int{1, 0, 1},
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := maxDistToClosest(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/maximize-grid-happiness/README.md b/problems/maximize-grid-happiness/README.md
deleted file mode 100644
index 55e3d6ec6..000000000
--- a/problems/maximize-grid-happiness/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-operations-to-reduce-x-to-zero "Minimum Operations to Reduce X to Zero")
-　　　　　　　　　　　　　　　　
-[Next >](../correct-a-binary-tree "Correct a Binary Tree")
-
-## [1659. Maximize Grid Happiness (Hard)](https://leetcode.com/problems/maximize-grid-happiness "最大化网格幸福感")
-
-<p>You are given four integers, <code>m</code>, <code>n</code>, <code>introvertsCount</code>, and <code>extrovertsCount</code>. You have an <code>m x n</code> grid, and there are two types of people: introverts and extroverts. There are <code>introvertsCount</code> introverts and <code>extrovertsCount</code> extroverts.</p>
-
-<p>You should decide how many people you want to live in the grid and assign each of them one grid cell. Note that you <strong>do not</strong> have to have all the people living in the grid.</p>
-
-<p>The <strong>happiness</strong> of each person is calculated as follows:</p>
-
-<ul>
-	<li>Introverts <strong>start</strong> with <code>120</code> happiness and <strong>lose</strong> <code>30</code> happiness for each neighbor (introvert or extrovert).</li>
-	<li>Extroverts <strong>start</strong> with <code>40</code> happiness and <strong>gain</strong> <code>20</code> happiness for each neighbor (introvert or extrovert).</li>
-</ul>
-
-<p>Neighbors live in the directly adjacent cells north, east, south, and west of a person&#39;s cell.</p>
-
-<p>The <strong>grid happiness</strong> is the <strong>sum</strong> of each person&#39;s happiness. Return<em> the <strong>maximum possible grid happiness</strong>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/grid_happiness.png" style="width: 261px; height: 121px;" />
-<pre>
-<strong>Input:</strong> m = 2, n = 3, introvertsCount = 1, extrovertsCount = 2
-<strong>Output:</strong> 240
-<strong>Explanation:</strong> Assume the grid is 1-indexed with coordinates (row, column).
-We can put the introvert in cell (1,1) and put the extroverts in cells (1,3) and (2,3).
-- Introvert at (1,1) happiness: 120 (starting happiness) - (0 * 30) (0 neighbors) = 120
-- Extrovert at (1,3) happiness: 40 (starting happiness) + (1 * 20) (1 neighbor) = 60
-- Extrovert at (2,3) happiness: 40 (starting happiness) + (1 * 20) (1 neighbor) = 60
-The grid happiness is 120 + 60 + 60 = 240.
-The above figure shows the grid in this example with each person&#39;s happiness. The introvert stays in the light green cell while the extroverts live on the light purple cells.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> m = 3, n = 1, introvertsCount = 2, extrovertsCount = 1
-<strong>Output:</strong> 260
-<strong>Explanation:</strong> Place the two introverts in (1,1) and (3,1) and the extrovert at (2,1).
-- Introvert at (1,1) happiness: 120 (starting happiness) - (1 * 30) (1 neighbor) = 90
-- Extrovert at (2,1) happiness: 40 (starting happiness) + (2 * 20) (2 neighbors) = 80
-- Introvert at (3,1) happiness: 120 (starting happiness) - (1 * 30) (1 neighbor) = 90
-The grid happiness is 90 + 80 + 90 = 260.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> m = 2, n = 2, introvertsCount = 4, extrovertsCount = 0
-<strong>Output:</strong> 240
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m, n &lt;= 5</code></li>
-	<li><code>0 &lt;= introvertsCount, extrovertsCount &lt;= min(m * n, 6)</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each cell, it has 3 options, either it is empty, or contains an introvert, or an extrovert.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can do DP where you maintain the state of the previous row, the number of remaining introverts and extroverts, the current row and column, and try the 3 options for each cell.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Assume that the previous columns in the current row already belong to the previous row.
-</details>
diff --git a/problems/maximize-number-of-nice-divisors/README.md b/problems/maximize-number-of-nice-divisors/README.md
deleted file mode 100644
index 69b41c77f..000000000
--- a/problems/maximize-number-of-nice-divisors/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../evaluate-the-bracket-pairs-of-a-string "Evaluate the Bracket Pairs of a String")
-　　　　　　　　　　　　　　　　
-[Next >](../ad-free-sessions "Ad-Free Sessions")
-
-## [1808. Maximize Number of Nice Divisors (Hard)](https://leetcode.com/problems/maximize-number-of-nice-divisors "好因子的最大数目")
-
-<p>You are given a positive integer <code>primeFactors</code>. You are asked to construct a positive integer <code>n</code> that satisfies the following conditions:</p>
-
-<ul>
-  <li>The number of prime factors of <code>n</code> (not necessarily distinct) is <strong>at most</strong> <code>primeFactors</code>.</li>
-  <li>The number of nice divisors of <code>n</code> is maximized. Note that a divisor of <code>n</code> is <strong>nice</strong> if it is divisible by every prime factor of <code>n</code>. For example, if <code>n = 12</code>, then its prime factors are <code>[2,2,3]</code>, then <code>6</code> and <code>12</code> are nice divisors, while <code>3</code> and <code>4</code> are not.</li>
-</ul>
-
-<p>Return <em>the number of nice divisors of</em> <code>n</code>. Since that number can be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>Note that a prime number is a natural number greater than <code>1</code> that is not a product of two smaller natural numbers. The prime factors of a number <code>n</code> is a list of prime numbers such that their product equals <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> primeFactors = 5
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> 200 is a valid value of n.
-It has 5 prime factors: [2,2,2,5,5], and it has 6 nice divisors: [10,20,40,50,100,200].
-There is not other value of n that has at most 5 prime factors and more nice divisors.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> primeFactors = 8
-<strong>Output:</strong> 18
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= primeFactors &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-
-### Similar Questions
-  1. [Integer Break](../integer-break) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The number of nice divisors is equal to the product of the count of each prime factor. Then the problem is reduced to: given n, find a sequence of numbers whose sum equals n and whose product is maximized.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-This sequence can have no numbers that are larger than 4. Proof: if it contains a number x that is larger than 4, then you can replace x with floor(x/2) and ceil(x/2), and floor(x/2) * ceil(x/2) > x. You can also replace 4s with two 2s. Hence, there will always be optimal solutions with only 2s and 3s.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If there are three 2s, you can replace them with two 3s to get a better product. Hence, you'll never have more than two 2s.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Keep adding 3s as long as n ≥ 5.
-</details>
diff --git a/problems/maximize-palindrome-length-from-subsequences/README.md b/problems/maximize-palindrome-length-from-subsequences/README.md
deleted file mode 100644
index d81e5e0b6..000000000
--- a/problems/maximize-palindrome-length-from-subsequences/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-score-from-performing-multiplication-operations "Maximum Score from Performing Multiplication Operations")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-features-by-popularity "Sort Features by Popularity")
-
-## [1771. Maximize Palindrome Length From Subsequences (Hard)](https://leetcode.com/problems/maximize-palindrome-length-from-subsequences "由子序列构造的最长回文串的长度")
-
-<p>You are given two strings, <code>word1</code> and <code>word2</code>. You want to construct a string in the following manner:</p>
-
-<ul>
-	<li>Choose some <strong>non-empty</strong> subsequence <code>subsequence1</code> from <code>word1</code>.</li>
-	<li>Choose some <strong>non-empty</strong> subsequence <code>subsequence2</code> from <code>word2</code>.</li>
-	<li>Concatenate the subsequences: <code>subsequence1 + subsequence2</code>, to make the string.</li>
-</ul>
-
-<p>Return <em>the <strong>length</strong> of the longest <strong>palindrome</strong> that can be constructed in the described manner. </em>If no palindromes can be constructed, return <code>0</code>.</p>
-
-<p>A <strong>subsequence</strong> of a string <code>s</code> is a string that can be made by deleting some (possibly none) characters from <code>s</code> without changing the order of the remaining characters.</p>
-
-<p>A <strong>palindrome</strong> is a string that reads the same forward&nbsp;as well as backward.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;cacb&quot;, word2 = &quot;cbba&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Choose &quot;ab&quot; from word1 and &quot;cba&quot; from word2 to make &quot;abcba&quot;, which is a palindrome.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;ab&quot;, word2 = &quot;ab&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Choose &quot;ab&quot; from word1 and &quot;a&quot; from word2 to make &quot;aba&quot;, which is a palindrome.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;aa&quot;, word2 = &quot;bb&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> You cannot construct a palindrome from the described method, so return 0.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word1.length, word2.length &lt;= 1000</code></li>
-	<li><code>word1</code> and <code>word2</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's ignore the non-empty subsequence constraint. We can concatenate the two strings and find the largest palindromic subsequence with dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Iterate through every pair of characters word1[i] and word2[j], and see if some palindrome begins with word1[i] and ends with word2[j]. This ensures that the subsequences are non-empty.
-</details>
diff --git a/problems/maximize-score-after-n-operations/README.md b/problems/maximize-score-after-n-operations/README.md
deleted file mode 100644
index 2435627b1..000000000
--- a/problems/maximize-score-after-n-operations/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-consecutive-values-you-can-make "Maximum Number of Consecutive Values You Can Make")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-ascending-subarray-sum "Maximum Ascending Subarray Sum")
-
-## [1799. Maximize Score After N Operations (Hard)](https://leetcode.com/problems/maximize-score-after-n-operations "N 次操作后的最大分数和")
-
-<p>You are given <code>nums</code>, an array of positive integers of size <code>2 * n</code>. You must perform <code>n</code> operations on this array.</p>
-
-<p>In the <code>i<sup>th</sup></code> operation <strong>(1-indexed)</strong>, you will:</p>
-
-<ul>
-	<li>Choose two elements, <code>x</code> and <code>y</code>.</li>
-	<li>Receive a score of <code>i * gcd(x, y)</code>.</li>
-	<li>Remove <code>x</code> and <code>y</code> from <code>nums</code>.</li>
-</ul>
-
-<p>Return <em>the maximum score you can receive after performing </em><code>n</code><em> operations.</em></p>
-
-<p>The function <code>gcd(x, y)</code> is the greatest common divisor of <code>x</code> and <code>y</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>&nbsp;The optimal choice of operations is:
-(1 * gcd(1, 2)) = 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,4,6,8]
-<strong>Output:</strong> 11
-<strong>Explanation:</strong>&nbsp;The optimal choice of operations is:
-(1 * gcd(3, 6)) + (2 * gcd(4, 8)) = 3 + 8 = 11
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5,6]
-<strong>Output:</strong> 14
-<strong>Explanation:</strong>&nbsp;The optimal choice of operations is:
-(1 * gcd(1, 5)) + (2 * gcd(2, 4)) + (3 * gcd(3, 6)) = 1 + 4 + 9 = 14
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 7</code></li>
-	<li><code>nums.length == 2 * n</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-  [[Number Theory](../../tag/number-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find every way to split the array until n groups of 2. Brute force recursion is acceptable.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Calculate the gcd of every pair and greedily multiply the largest gcds.
-</details>
diff --git a/problems/maximize-sum-of-array-after-k-negations/README.md b/problems/maximize-sum-of-array-after-k-negations/README.md
deleted file mode 100644
index 881f9c9c8..000000000
--- a/problems/maximize-sum-of-array-after-k-negations/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-consecutive-ones-iii "Max Consecutive Ones III")
-　　　　　　　　　　　　　　　　
-[Next >](../clumsy-factorial "Clumsy Factorial")
-
-## [1005. Maximize Sum Of Array After K Negations (Easy)](https://leetcode.com/problems/maximize-sum-of-array-after-k-negations "K 次取反后最大化的数组和")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, modify the array in the following way:</p>
-
-<ul>
-	<li>choose an index <code>i</code> and replace <code>nums[i]</code> with <code>-nums[i]</code>.</li>
-</ul>
-
-<p>You should apply this process exactly <code>k</code> times. You may choose the same index <code>i</code> multiple times.</p>
-
-<p>Return <em>the largest possible sum of the array after modifying it in this way</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,3], k = 1
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Choose index 1 and nums becomes [4,-2,3].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,-1,0,2], k = 3
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Choose indices (1, 2, 2) and nums becomes [3,1,0,2].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,-3,-1,5,-4], k = 2
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> Choose indices (1, 4) and nums becomes [2,3,-1,5,4].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/maximize-sum-of-array-after-k-negations/maximize_sum_of_array_after_k_negations.go b/problems/maximize-sum-of-array-after-k-negations/maximize_sum_of_array_after_k_negations.go
deleted file mode 100644
index c00535350..000000000
--- a/problems/maximize-sum-of-array-after-k-negations/maximize_sum_of_array_after_k_negations.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem1005
-
-import "sort"
-
-func largestSumAfterKNegations(A []int, K int) int {
-	sort.Ints(A)
-	ans, min := 0, A[len(A)-1]
-	for _, v := range A {
-		if K > 0 && v <= 0 {
-			K, v = K-1, -v
-		}
-		if v < min {
-			min = v
-		}
-		ans += v
-	}
-	if K&1 == 1 {
-		ans -= min * 2
-	}
-	return ans
-}
diff --git a/problems/maximize-sum-of-array-after-k-negations/maximize_sum_of_array_after_k_negations_test.go b/problems/maximize-sum-of-array-after-k-negations/maximize_sum_of_array_after_k_negations_test.go
deleted file mode 100644
index d506d5842..000000000
--- a/problems/maximize-sum-of-array-after-k-negations/maximize_sum_of_array_after_k_negations_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1005
-
-import "testing"
-
-type testType struct {
-	in   []int
-	k    int
-	want int
-}
-
-func TestLargestSumAfterKNegations(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{4, 2, 3},
-			k:    1,
-			want: 5,
-		},
-		{
-			in:   []int{3, -1, 0, 2},
-			k:    3,
-			want: 6,
-		},
-		{
-			in:   []int{2, -3, -1, 5, -4},
-			k:    2,
-			want: 13,
-		},
-	}
-	for _, tt := range tests {
-		got := largestSumAfterKNegations(tt.in, tt.k)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/maximize-the-beauty-of-the-garden/README.md b/problems/maximize-the-beauty-of-the-garden/README.md
deleted file mode 100644
index 20133a4ef..000000000
--- a/problems/maximize-the-beauty-of-the-garden/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../make-the-xor-of-all-segments-equal-to-zero "Make the XOR of All Segments Equal to Zero")
-　　　　　　　　　　　　　　　　
-[Next >](../primary-department-for-each-employee "Primary Department for Each Employee")
-
-## [1788. Maximize the Beauty of the Garden (Hard)](https://leetcode.com/problems/maximize-the-beauty-of-the-garden "最大化花园的美观度")
-
-
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider every possible beauty and its first and last index in flowers.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Remove all flowers with negative beauties within those indices.
-</details>
diff --git a/problems/maximize-the-confusion-of-an-exam/README.md b/problems/maximize-the-confusion-of-an-exam/README.md
deleted file mode 100644
index f750e9c89..000000000
--- a/problems/maximize-the-confusion-of-an-exam/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-pairs-of-strings-with-concatenation-equal-to-target "Number of Pairs of Strings With Concatenation Equal to Target")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-ways-to-partition-an-array "Maximum Number of Ways to Partition an Array")
-
-## [2024. Maximize the Confusion of an Exam (Medium)](https://leetcode.com/problems/maximize-the-confusion-of-an-exam "考试的最大困扰度")
-
-<p>A teacher is writing a test with <code>n</code> true/false questions, with <code>&#39;T&#39;</code> denoting true and <code>&#39;F&#39;</code> denoting false. He wants to confuse the students by <strong>maximizing</strong> the number of <strong>consecutive</strong> questions with the <strong>same</strong> answer (multiple trues or multiple falses in a row).</p>
-
-<p>You are given a string <code>answerKey</code>, where <code>answerKey[i]</code> is the original answer to the <code>i<sup>th</sup></code> question. In addition, you are given an integer <code>k</code>, the maximum number of times you may perform the following operation:</p>
-
-<ul>
-	<li>Change the answer key for any question to <code>&#39;T&#39;</code> or <code>&#39;F&#39;</code> (i.e., set <code>answerKey[i]</code> to <code>&#39;T&#39;</code> or <code>&#39;F&#39;</code>).</li>
-</ul>
-
-<p>Return <em>the <strong>maximum</strong> number of consecutive</em> <code>&#39;T&#39;</code>s or <code>&#39;F&#39;</code>s <em>in the answer key after performing the operation at most</em> <code>k</code> <em>times</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> answerKey = &quot;TTFF&quot;, k = 2
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> We can replace both the &#39;F&#39;s with &#39;T&#39;s to make answerKey = &quot;<u>TTTT</u>&quot;.
-There are four consecutive &#39;T&#39;s.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> answerKey = &quot;TFFT&quot;, k = 1
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We can replace the first &#39;T&#39; with an &#39;F&#39; to make answerKey = &quot;<u>FFF</u>T&quot;.
-Alternatively, we can replace the second &#39;T&#39; with an &#39;F&#39; to make answerKey = &quot;T<u>FFF</u>&quot;.
-In both cases, there are three consecutive &#39;F&#39;s.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> answerKey = &quot;TTFTTFTT&quot;, k = 1
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> We can replace the first &#39;F&#39; to make answerKey = &quot;<u>TTTTT</u>FTT&quot;
-Alternatively, we can replace the second &#39;F&#39; to make answerKey = &quot;TTF<u>TTTTT</u>&quot;. 
-In both cases, there are five consecutive &#39;T&#39;s.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == answerKey.length</code></li>
-	<li><code>1 &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>answerKey[i]</code> is either <code>&#39;T&#39;</code> or <code>&#39;F&#39;</code></li>
-	<li><code>1 &lt;= k &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we use the maximum length at the previous position to help us find the answer for the current position?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use binary search to find the maximum consecutive same answer at every position?
-</details>
diff --git a/problems/maximum-69-number/README.md b/problems/maximum-69-number/README.md
deleted file mode 100644
index 79c1b13da..000000000
--- a/problems/maximum-69-number/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ads-performance "Ads Performance")
-　　　　　　　　　　　　　　　　
-[Next >](../print-words-vertically "Print Words Vertically")
-
-## [1323. Maximum 69 Number (Easy)](https://leetcode.com/problems/maximum-69-number "6 和 9 组成的最大数字")
-
-<p>Given a positive integer <code>num</code> consisting only of digits 6 and 9.</p>
-
-<p>Return the maximum number you can get by changing <strong>at most</strong> one digit (6 becomes 9, and 9 becomes 6).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 9669
-<strong>Output:</strong> 9969
-<strong>Explanation:</strong> 
-Changing the first digit results in 6669.
-Changing the second digit results in 9969.
-Changing the third digit results in 9699.
-Changing the fourth digit results in 9666.&nbsp;
-The maximum number is 9969.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 9996
-<strong>Output:</strong> 9999
-<strong>Explanation:</strong> Changing the last digit 6 to 9 results in the maximum number.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 9999
-<strong>Output:</strong> 9999
-<strong>Explanation:</strong> It is better not to apply any change.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num &lt;= 10^4</code></li>
-	<li><code>num</code>&#39;s digits are 6 or 9.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert the number in an array of its digits.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Brute force on every digit to get the maximum number.
-</details>
diff --git a/problems/maximum-absolute-sum-of-any-subarray/README.md b/problems/maximum-absolute-sum-of-any-subarray/README.md
deleted file mode 100644
index 77031437a..000000000
--- a/problems/maximum-absolute-sum-of-any-subarray/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-unique-elements "Sum of Unique Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-length-of-string-after-deleting-similar-ends "Minimum Length of String After Deleting Similar Ends")
-
-## [1749. Maximum Absolute Sum of Any Subarray (Medium)](https://leetcode.com/problems/maximum-absolute-sum-of-any-subarray "任意子数组和的绝对值的最大值")
-
-<p>You are given an integer array <code>nums</code>. The <strong>absolute sum</strong> of a subarray <code>[nums<sub>l</sub>, nums<sub>l+1</sub>, ..., nums<sub>r-1</sub>, nums<sub>r</sub>]</code> is <code>abs(nums<sub>l</sub> + nums<sub>l+1</sub> + ... + nums<sub>r-1</sub> + nums<sub>r</sub>)</code>.</p>
-
-<p>Return <em>the <strong>maximum</strong> absolute sum of any <strong>(possibly empty)</strong> subarray of </em><code>nums</code>.</p>
-
-<p>Note that <code>abs(x)</code> is defined as follows:</p>
-
-<ul>
-	<li>If <code>x</code> is a negative integer, then <code>abs(x) = -x</code>.</li>
-	<li>If <code>x</code> is a non-negative integer, then <code>abs(x) = x</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,-3,2,3,-4]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The subarray [2,3] has absolute sum = abs(2+3) = abs(5) = 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,-5,1,-4,3,-2]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> The subarray [-5,1,-4] has absolute sum = abs(-5+1-4) = abs(-8) = 8.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if we asked for maximum sum, not absolute sum?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-It's a standard problem that can be solved by Kadane's algorithm.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The key idea is the max absolute sum will be either the max sum or the min sum.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-So just run kadane twice, once calculating the max sum and once calculating the min sum.
-</details>
diff --git a/problems/maximum-alternating-subarray-sum/README.md b/problems/maximum-alternating-subarray-sum/README.md
deleted file mode 100644
index d761dc4d7..000000000
--- a/problems/maximum-alternating-subarray-sum/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partition-array-into-two-arrays-to-minimize-sum-difference "Partition Array Into Two Arrays to Minimize Sum Difference")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-moves-to-seat-everyone "Minimum Number of Moves to Seat Everyone")
-
-## [2036. Maximum Alternating Subarray Sum (Medium)](https://leetcode.com/problems/maximum-alternating-subarray-sum "最大交替子数组和")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can Kadane's Algorithm help us?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you convert all the numbers at odd indices to the negative version of that number, the problem simplifies to finding the maximum subarray sum.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-However, this strategy needs you to start each subarray at an even index.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Do the same except converting all the numbers at even indices to the negative version of that number.
-</details>
diff --git a/problems/maximum-alternating-subsequence-sum/README.md b/problems/maximum-alternating-subsequence-sum/README.md
deleted file mode 100644
index 340f9b788..000000000
--- a/problems/maximum-alternating-subsequence-sum/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-all-occurrences-of-a-substring "Remove All Occurrences of a Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../design-movie-rental-system "Design Movie Rental System")
-
-## [1911. Maximum Alternating Subsequence Sum (Medium)](https://leetcode.com/problems/maximum-alternating-subsequence-sum "最大子序列交替和")
-
-<p>The <strong>alternating sum</strong> of a <strong>0-indexed</strong> array is defined as the <strong>sum</strong> of the elements at <strong>even</strong> indices <strong>minus</strong> the <strong>sum</strong> of the elements at <strong>odd</strong> indices.</p>
-
-<ul>
-	<li>For example, the alternating sum of <code>[4,2,5,3]</code> is <code>(4 + 5) - (2 + 3) = 4</code>.</li>
-</ul>
-
-<p>Given an array <code>nums</code>, return <em>the <strong>maximum alternating sum</strong> of any subsequence of </em><code>nums</code><em> (after <strong>reindexing</strong> the elements of the subsequence)</em>.</p>
-
-<ul>
-</ul>
-
-<p>A <strong>subsequence</strong> of an array is a new array generated from the original array by deleting some elements (possibly none) without changing the remaining elements&#39; relative order. For example, <code>[2,7,4]</code> is a subsequence of <code>[4,<u>2</u>,3,<u>7</u>,2,1,<u>4</u>]</code> (the underlined elements), while <code>[2,4,2]</code> is not.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [<u>4</u>,<u>2</u>,<u>5</u>,3]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> It is optimal to choose the subsequence [4,2,5] with alternating sum (4 + 5) - 2 = 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,6,7,<u>8</u>]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> It is optimal to choose the subsequence [8] with alternating sum 8.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [<u>6</u>,2,<u>1</u>,2,4,<u>5</u>]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> It is optimal to choose the subsequence [6,1,5] with alternating sum (6 + 5) - 1 = 10.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Maximum Alternating Subarray Sum](../maximum-alternating-subarray-sum) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is only tracking a single sum enough to solve the problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How does tracking an odd sum and an even sum reduce the number of states?
-</details>
diff --git a/problems/maximum-and-sum-of-array/README.md b/problems/maximum-and-sum-of-array/README.md
deleted file mode 100644
index c3a632e65..000000000
--- a/problems/maximum-and-sum-of-array/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../removing-minimum-number-of-magic-beans "Removing Minimum Number of Magic Beans")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-winning-streak "Longest Winning Streak")
-
-## [2172. Maximum AND Sum of Array (Hard)](https://leetcode.com/problems/maximum-and-sum-of-array "数组的最大与和")
-
-<p>You are given an integer array <code>nums</code> of length <code>n</code> and an integer <code>numSlots</code> such that <code>2 * numSlots &gt;= n</code>. There are <code>numSlots</code> slots numbered from <code>1</code> to <code>numSlots</code>.</p>
-
-<p>You have to place all <code>n</code> integers into the slots such that each slot contains at <strong>most</strong> two numbers. The <strong>AND sum</strong> of a given placement is the sum of the <strong>bitwise</strong> <code>AND</code> of every number with its respective slot number.</p>
-
-<ul>
-	<li>For example, the <strong>AND sum</strong> of placing the numbers <code>[1, 3]</code> into slot <u><code>1</code></u> and <code>[4, 6]</code> into slot <u><code>2</code></u> is equal to <code>(1 AND <u>1</u>) + (3 AND <u>1</u>) + (4 AND <u>2</u>) + (6 AND <u>2</u>) = 1 + 1 + 0 + 2 = 4</code>.</li>
-</ul>
-
-<p>Return <em>the maximum possible <strong>AND sum</strong> of </em><code>nums</code><em> given </em><code>numSlots</code><em> slots.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5,6], numSlots = 3
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> One possible placement is [1, 4] into slot <u>1</u>, [2, 6] into slot <u>2</u>, and [3, 5] into slot <u>3</u>. 
-This gives the maximum AND sum of (1 AND <u>1</u>) + (4 AND <u>1</u>) + (2 AND <u>2</u>) + (6 AND <u>2</u>) + (3 AND <u>3</u>) + (5 AND <u>3</u>) = 1 + 0 + 2 + 2 + 3 + 1 = 9.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,10,4,7,1], numSlots = 9
-<strong>Output:</strong> 24
-<strong>Explanation:</strong> One possible placement is [1, 1] into slot <u>1</u>, [3] into slot <u>3</u>, [4] into slot <u>4</u>, [7] into slot <u>7</u>, and [10] into slot <u>9</u>.
-This gives the maximum AND sum of (1 AND <u>1</u>) + (1 AND <u>1</u>) + (3 AND <u>3</u>) + (4 AND <u>4</u>) + (7 AND <u>7</u>) + (10 AND <u>9</u>) = 1 + 1 + 3 + 4 + 7 + 8 = 24.
-Note that slots 2, 5, 6, and 8 are empty which is permitted.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= numSlots &lt;= 9</code></li>
-	<li><code>1 &lt;= n &lt;= 2 * numSlots</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 15</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you think of a dynamic programming solution to this problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you use a bitmask to represent the state of the slots?
-</details>
diff --git a/problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts/README.md b/problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts/README.md
deleted file mode 100644
index 43b1a9eeb..000000000
--- a/problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-product-of-two-elements-in-an-array "Maximum Product of Two Elements in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../reorder-routes-to-make-all-paths-lead-to-the-city-zero "Reorder Routes to Make All Paths Lead to the City Zero")
-
-## [1465. Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts (Medium)](https://leetcode.com/problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts "切割后面积最大的蛋糕")
-
-<p>You are given a rectangular cake of size <code>h x w</code> and two arrays of integers <code>horizontalCuts</code> and <code>verticalCuts</code> where:</p>
-
-<ul>
-	<li><code>horizontalCuts[i]</code> is the distance from the top of the rectangular cake to the <code>i<sup>th</sup></code> horizontal cut and similarly, and</li>
-	<li><code>verticalCuts[j]</code> is the distance from the left of the rectangular cake to the <code>j<sup>th</sup></code> vertical cut.</li>
-</ul>
-
-<p>Return <em>the maximum area of a piece of cake after you cut at each horizontal and vertical position provided in the arrays</em> <code>horizontalCuts</code> <em>and</em> <code>verticalCuts</code>. Since the answer can be a large number, return this <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/05/14/leetcode_max_area_2.png" style="width: 225px; height: 240px;" />
-<pre>
-<strong>Input:</strong> h = 5, w = 4, horizontalCuts = [1,2,4], verticalCuts = [1,3]
-<strong>Output:</strong> 4 
-<strong>Explanation:</strong> The figure above represents the given rectangular cake. Red lines are the horizontal and vertical cuts. After you cut the cake, the green piece of cake has the maximum area.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/05/14/leetcode_max_area_3.png" style="width: 225px; height: 240px;" />
-<pre>
-<strong>Input:</strong> h = 5, w = 4, horizontalCuts = [3,1], verticalCuts = [1]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The figure above represents the given rectangular cake. Red lines are the horizontal and vertical cuts. After you cut the cake, the green and yellow pieces of cake have the maximum area.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> h = 5, w = 4, horizontalCuts = [3], verticalCuts = [3]
-<strong>Output:</strong> 9
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= h, w &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= horizontalCuts.length &lt;= min(h - 1, 10<sup>5</sup>)</code></li>
-	<li><code>1 &lt;= verticalCuts.length &lt;= min(w - 1, 10<sup>5</sup>)</code></li>
-	<li><code>1 &lt;= horizontalCuts[i] &lt; h</code></li>
-	<li><code>1 &lt;= verticalCuts[i] &lt; w</code></li>
-	<li>All the elements in <code>horizontalCuts</code> are distinct.</li>
-	<li>All the elements in <code>verticalCuts</code> are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the arrays, then compute the maximum difference between two consecutive elements for horizontal cuts and vertical cuts.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The answer is the product of these maximum values in horizontal cuts and vertical cuts.
-</details>
diff --git a/problems/maximum-ascending-subarray-sum/README.md b/problems/maximum-ascending-subarray-sum/README.md
deleted file mode 100644
index 349c6752a..000000000
--- a/problems/maximum-ascending-subarray-sum/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximize-score-after-n-operations "Maximize Score After N Operations")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-orders-in-the-backlog "Number of Orders in the Backlog")
-
-## [1800. Maximum Ascending Subarray Sum (Easy)](https://leetcode.com/problems/maximum-ascending-subarray-sum "最大升序子数组和")
-
-<p>Given an array of positive integers <code>nums</code>, return the <em>maximum possible sum of an <strong>ascending</strong> subarray in </em><code>nums</code>.</p>
-
-<p>A subarray is defined as a contiguous sequence of numbers in an array.</p>
-
-<p>A subarray <code>[nums<sub>l</sub>, nums<sub>l+1</sub>, ..., nums<sub>r-1</sub>, nums<sub>r</sub>]</code> is <strong>ascending</strong> if for all <code>i</code> where <code>l &lt;= i &lt; r</code>, <code>nums<sub>i </sub> &lt; nums<sub>i+1</sub></code>. Note that a subarray of size <code>1</code> is <strong>ascending</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,20,30,5,10,50]
-<strong>Output:</strong> 65
-<strong>Explanation: </strong>[5,10,50] is the ascending subarray with the maximum sum of 65.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,20,30,40,50]
-<strong>Output:</strong> 150
-<strong>Explanation: </strong>[10,20,30,40,50] is the ascending subarray with the maximum sum of 150.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [12,17,15,13,10,11,12]
-<strong>Output:</strong> 33
-<strong>Explanation: </strong>[10,11,12] is the ascending subarray with the maximum sum of 33.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Find Good Days to Rob the Bank](../find-good-days-to-rob-the-bank) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-It is fast enough to check all possible subarrays
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The end of each ascending subarray will be the start of the next
-</details>
diff --git a/problems/maximum-average-pass-ratio/README.md b/problems/maximum-average-pass-ratio/README.md
deleted file mode 100644
index d4bcfbbb9..000000000
--- a/problems/maximum-average-pass-ratio/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-center-of-star-graph "Find Center of Star Graph")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-score-of-a-good-subarray "Maximum Score of a Good Subarray")
-
-## [1792. Maximum Average Pass Ratio (Medium)](https://leetcode.com/problems/maximum-average-pass-ratio "最大平均通过率")
-
-<p>There is a school that has classes of students and each class will be having a final exam. You are given a 2D integer array <code>classes</code>, where <code>classes[i] = [pass<sub>i</sub>, total<sub>i</sub>]</code>. You know beforehand that in the <code>i<sup>th</sup></code> class, there are <code>total<sub>i</sub></code> total students, but only <code>pass<sub>i</sub></code> number of students will pass the exam.</p>
-
-<p>You are also given an integer <code>extraStudents</code>. There are another <code>extraStudents</code> brilliant students that are <strong>guaranteed</strong> to pass the exam of any class they are assigned to. You want to assign each of the <code>extraStudents</code> students to a class in a way that <strong>maximizes</strong> the <strong>average</strong> pass ratio across <strong>all</strong> the classes.</p>
-
-<p>The <strong>pass ratio</strong> of a class is equal to the number of students of the class that will pass the exam divided by the total number of students of the class. The <strong>average pass ratio</strong> is the sum of pass ratios of all the classes divided by the number of the classes.</p>
-
-<p>Return <em>the <strong>maximum</strong> possible average pass ratio after assigning the </em><code>extraStudents</code><em> students. </em>Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> classes = [[1,2],[3,5],[2,2]], <code>extraStudents</code> = 2
-<strong>Output:</strong> 0.78333
-<strong>Explanation:</strong> You can assign the two extra students to the first class. The average pass ratio will be equal to (3/4 + 3/5 + 2/2) / 3 = 0.78333.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> classes = [[2,4],[3,9],[4,5],[2,10]], <code>extraStudents</code> = 4
-<strong>Output:</strong> 0.53485
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= classes.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>classes[i].length == 2</code></li>
-	<li><code>1 &lt;= pass<sub>i</sub> &lt;= total<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= extraStudents &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Pay attention to how much the pass ratio changes when you add a student to the class. If you keep adding students, what happens to the change in pass ratio? The more students you add to a class, the smaller the change in pass ratio becomes.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Since the change in the pass ratio is always decreasing with the more students you add, then the very first student you add to each class is the one that makes the biggest change in the pass ratio.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Because each class's pass ratio is weighted equally, it's always optimal to put the student in the class that makes the biggest change among all the other classes.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Keep a max heap of the current class sizes and order them by the change in pass ratio. For each extra student, take the top of the heap, update the class size, and put it back in the heap.
-</details>
diff --git a/problems/maximum-average-subarray-i/README.md b/problems/maximum-average-subarray-i/README.md
deleted file mode 100644
index 47c8abf56..000000000
--- a/problems/maximum-average-subarray-i/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-search-autocomplete-system "Design Search Autocomplete System")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-average-subarray-ii "Maximum Average Subarray II")
-
-## [643. Maximum Average Subarray I (Easy)](https://leetcode.com/problems/maximum-average-subarray-i "子数组最大平均数 I")
-
-<p>You are given an integer array <code>nums</code> consisting of <code>n</code> elements, and an integer <code>k</code>.</p>
-
-<p>Find a contiguous subarray whose <strong>length is equal to</strong> <code>k</code> that has the maximum average value and return <em>this value</em>. Any answer with a calculation error less than <code>10<sup>-5</sup></code> will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,12,-5,-6,50,3], k = 4
-<strong>Output:</strong> 12.75000
-<strong>Explanation:</strong> Maximum average is (12 - 5 - 6 + 50) / 4 = 51 / 4 = 12.75
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5], k = 1
-<strong>Output:</strong> 5.00000
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= k &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Maximum Average Subarray II](../maximum-average-subarray-ii) (Hard)
diff --git a/problems/maximum-average-subarray-i/maximum_average_subarray_i.go b/problems/maximum-average-subarray-i/maximum_average_subarray_i.go
deleted file mode 100644
index 7d6150bdd..000000000
--- a/problems/maximum-average-subarray-i/maximum_average_subarray_i.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem643
-
-func findMaxAverage(nums []int, k int) float64 {
-	max, sum := 0, 0
-	for i, v := range nums {
-		sum += v
-		if i == k-1 {
-			max = sum
-		} else if i >= k {
-			sum -= nums[i-k]
-		}
-		if sum > max {
-			max = sum
-		}
-	}
-	return float64(max) / float64(k)
-}
diff --git a/problems/maximum-average-subarray-i/maximum_average_subarray_i_test.go b/problems/maximum-average-subarray-i/maximum_average_subarray_i_test.go
deleted file mode 100644
index 17738a5fe..000000000
--- a/problems/maximum-average-subarray-i/maximum_average_subarray_i_test.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem643
-
-import "testing"
-
-type testType struct {
-	nums []int
-	k    int
-	want float64
-}
-
-func TestFindMaxAverage(t *testing.T) {
-	tests := [...]testType{
-		{
-			nums: []int{1, 12, -5, -6, 50, 3},
-			k:    4,
-			want: 12.75,
-		},
-	}
-	for _, tt := range tests {
-		got := findMaxAverage(tt.nums, tt.k)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.nums, tt.k, got, tt.want)
-		}
-	}
-}
diff --git a/problems/maximum-average-subarray-ii/README.md b/problems/maximum-average-subarray-ii/README.md
deleted file mode 100644
index 323fe56de..000000000
--- a/problems/maximum-average-subarray-ii/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-average-subarray-i "Maximum Average Subarray I")
-　　　　　　　　　　　　　　　　
-[Next >](../set-mismatch "Set Mismatch")
-
-## [644. Maximum Average Subarray II (Hard)](https://leetcode.com/problems/maximum-average-subarray-ii "子数组最大平均数 II")
-
-<p>
-Given an array consisting of <code>n</code> integers, find the contiguous subarray whose <b>length is greater than or equal to</b> <code>k</code> that has the maximum average value. And you need to output the maximum average value.
-</p>
-
-
-<p><b>Example 1:</b><br />
-<pre>
-<b>Input:</b> [1,12,-5,-6,50,3], k = 4
-<b>Output:</b> 12.75
-<b>Explanation:</b>
-when length is 5, maximum average value is 10.8,
-when length is 6, maximum average value is 9.16667.
-Thus return 12.75.
-</pre>
-</p>
-
-
-<p><b>Note:</b><br>
-<ol>
-<li>1 <= <code>k</code> <= <code>n</code> <= 10,000.</li>
-<li>Elements of the given array will be in range [-10,000, 10,000].</li>
-<li>The answer with the calculation error less than 10<sup>-5</sup> will be accepted.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Maximum Average Subarray I](../maximum-average-subarray-i) (Easy)
diff --git a/problems/maximum-average-subarray-ii/maximum_average_subarray_ii.go b/problems/maximum-average-subarray-ii/maximum_average_subarray_ii.go
deleted file mode 100644
index 02e0a1b03..000000000
--- a/problems/maximum-average-subarray-ii/maximum_average_subarray_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem644
diff --git a/problems/maximum-average-subarray-ii/maximum_average_subarray_ii_test.go b/problems/maximum-average-subarray-ii/maximum_average_subarray_ii_test.go
deleted file mode 100644
index 02e0a1b03..000000000
--- a/problems/maximum-average-subarray-ii/maximum_average_subarray_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem644
diff --git a/problems/maximum-average-subtree/README.md b/problems/maximum-average-subtree/README.md
deleted file mode 100644
index 87f334554..000000000
--- a/problems/maximum-average-subtree/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-vowels-from-a-string "Remove Vowels from a String")
-　　　　　　　　　　　　　　　　
-[Next >](../divide-array-into-increasing-sequences "Divide Array Into Increasing Sequences")
-
-## [1120. Maximum Average Subtree (Medium)](https://leetcode.com/problems/maximum-average-subtree "子树的最大平均值")
-
-<p>Given the <code>root</code> of a binary tree, find the maximum average value of any subtree of that tree.</p>
-
-<p>(A subtree of a tree is any node of that tree plus all its descendants. The average value of a tree is the sum of its values, divided by the number of nodes.)</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/04/09/1308_example_1.png" style="width: 132px; height: 123px;" /></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[5,6,1]</span>
-<strong>Output: </strong><span id="example-output-1">6.00000</span>
-<strong>Explanation: </strong>
-For the node with value = 5 we have an average of (5 + 6 + 1) / 3 = 4.
-For the node with value = 6 we have an average of 6 / 1 = 6.
-For the node with value = 1 we have an average of 1 / 1 = 1.
-So the answer is 6 which is the maximum.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>The number of nodes in the tree is between <code>1</code> and <code>5000</code>.</li>
-	<li>Each node will have a value between <code>0</code> and <code>100000</code>.</li>
-	<li>Answers will be accepted as correct if they are within <code>10^-5</code> of the correct answer.</li>
-</ol>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Count Nodes Equal to Sum of Descendants](../count-nodes-equal-to-sum-of-descendants) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you find the sum of values and the number of nodes for every sub-tree ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you find the sum of values and the number of nodes for a sub-tree given the sum of values and the number of nodes of it's left and right sub-trees ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use depth first search to recursively find the solution for the children of a node then use their solutions to compute the current node's solution.
-</details>
diff --git a/problems/maximum-binary-string-after-change/README.md b/problems/maximum-binary-string-after-change/README.md
deleted file mode 100644
index 8f105f46c..000000000
--- a/problems/maximum-binary-string-after-change/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../average-waiting-time "Average Waiting Time")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-adjacent-swaps-for-k-consecutive-ones "Minimum Adjacent Swaps for K Consecutive Ones")
-
-## [1702. Maximum Binary String After Change (Medium)](https://leetcode.com/problems/maximum-binary-string-after-change "修改后的最大二进制字符串")
-
-<p>You are given a binary string <code>binary</code> consisting of only <code>0</code>&#39;s or <code>1</code>&#39;s. You can apply each of the following operations any number of times:</p>
-
-<ul>
-	<li>Operation 1: If the number contains the substring <code>&quot;00&quot;</code>, you can replace it with <code>&quot;10&quot;</code>.
-	<ul>
-		<li>For example, <code>&quot;<u>00</u>010&quot; -&gt; &quot;<u>10</u>010</code>&quot;</li>
-	</ul>
-	</li>
-	<li>Operation 2: If the number contains the substring <code>&quot;10&quot;</code>, you can replace it with <code>&quot;01&quot;</code>.
-	<ul>
-		<li>For example, <code>&quot;000<u>10</u>&quot; -&gt; &quot;000<u>01</u>&quot;</code></li>
-	</ul>
-	</li>
-</ul>
-
-<p><em>Return the <strong>maximum binary string</strong> you can obtain after any number of operations. Binary string <code>x</code> is greater than binary string <code>y</code> if <code>x</code>&#39;s decimal representation is greater than <code>y</code>&#39;s decimal representation.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> binary = &quot;000110&quot;
-<strong>Output:</strong> &quot;111011&quot;
-<strong>Explanation:</strong> A valid transformation sequence can be:
-&quot;0001<u>10</u>&quot; -&gt; &quot;0001<u>01</u>&quot; 
-&quot;<u>00</u>0101&quot; -&gt; &quot;<u>10</u>0101&quot; 
-&quot;1<u>00</u>101&quot; -&gt; &quot;1<u>10</u>101&quot; 
-&quot;110<u>10</u>1&quot; -&gt; &quot;110<u>01</u>1&quot; 
-&quot;11<u>00</u>11&quot; -&gt; &quot;11<u>10</u>11&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> binary = &quot;01&quot;
-<strong>Output:</strong> &quot;01&quot;
-<strong>Explanation:</strong>&nbsp;&quot;01&quot; cannot be transformed any further.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= binary.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>binary</code> consist of <code>&#39;0&#39;</code> and <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that with the operations, you can always make the string only contain at most 1 zero.
-</details>
diff --git a/problems/maximum-binary-tree-ii/README.md b/problems/maximum-binary-tree-ii/README.md
deleted file mode 100644
index b720ca6e7..000000000
--- a/problems/maximum-binary-tree-ii/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-town-judge "Find the Town Judge")
-　　　　　　　　　　　　　　　　
-[Next >](../available-captures-for-rook "Available Captures for Rook")
-
-## [998. Maximum Binary Tree II (Medium)](https://leetcode.com/problems/maximum-binary-tree-ii "最大二叉树 II")
-
-<p>A <strong>maximum tree</strong> is a tree where every node has a value greater than any other value in its subtree.</p>
-
-<p>You are given the <code>root</code> of a maximum binary tree and an integer <code>val</code>.</p>
-
-<p>Just as in the <a href="https://leetcode.com/problems/maximum-binary-tree/" target="_blank">previous problem</a>, the given tree was constructed from a list <code>a</code> (<code>root = Construct(a)</code>) recursively with the following <code>Construct(a)</code> routine:</p>
-
-<ul>
-	<li>If <code>a</code> is empty, return <code>null</code>.</li>
-	<li>Otherwise, let <code>a[i]</code> be the largest element of <code>a</code>. Create a <code>root</code> node with the value <code>a[i]</code>.</li>
-	<li>The left child of <code>root</code> will be <code>Construct([a[0], a[1], ..., a[i - 1]])</code>.</li>
-	<li>The right child of <code>root</code> will be <code>Construct([a[i + 1], a[i + 2], ..., a[a.length - 1]])</code>.</li>
-	<li>Return <code>root</code>.</li>
-</ul>
-
-<p>Note that we were not given <code>a</code> directly, only a root node <code>root = Construct(a)</code>.</p>
-
-<p>Suppose <code>b</code> is a copy of <code>a</code> with the value <code>val</code> appended to it. It is guaranteed that <code>b</code> has unique values.</p>
-
-<p>Return <code>Construct(b)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/09/maxtree1.JPG" style="width: 376px; height: 235px;" />
-<pre>
-<strong>Input:</strong> root = [4,1,3,null,null,2], val = 5
-<strong>Output:</strong> [5,4,null,1,3,null,null,2]
-<strong>Explanation:</strong> a = [1,4,2,3], b = [1,4,2,3,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/09/maxtree21.JPG" style="width: 358px; height: 156px;" />
-<pre>
-<strong>Input:</strong> root = [5,2,4,null,1], val = 3
-<strong>Output:</strong> [5,2,4,null,1,null,3]
-<strong>Explanation:</strong> a = [2,1,5,4], b = [2,1,5,4,3]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/09/maxtree3.JPG" style="width: 404px; height: 180px;" />
-<pre>
-<strong>Input:</strong> root = [5,2,3,null,1], val = 4
-<strong>Output:</strong> [5,2,4,null,1,3]
-<strong>Explanation:</strong> a = [2,1,5,3], b = [2,1,5,3,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 100]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
-	<li>All the values of the tree are <strong>unique</strong>.</li>
-	<li><code>1 &lt;= val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Maximum Binary Tree](../maximum-binary-tree) (Medium)
diff --git a/problems/maximum-binary-tree-ii/maximum_binary_tree_ii.go b/problems/maximum-binary-tree-ii/maximum_binary_tree_ii.go
deleted file mode 100644
index e77abd09a..000000000
--- a/problems/maximum-binary-tree-ii/maximum_binary_tree_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem998
diff --git a/problems/maximum-binary-tree/README.md b/problems/maximum-binary-tree/README.md
deleted file mode 100644
index c2a8af6e9..000000000
--- a/problems/maximum-binary-tree/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-sum-iv-input-is-a-bst "Two Sum IV - Input is a BST")
-　　　　　　　　　　　　　　　　
-[Next >](../print-binary-tree "Print Binary Tree")
-
-## [654. Maximum Binary Tree (Medium)](https://leetcode.com/problems/maximum-binary-tree "最大二叉树")
-
-<p>You are given an integer array <code>nums</code> with no duplicates. A <strong>maximum binary tree</strong> can be built recursively from <code>nums</code> using the following algorithm:</p>
-
-<ol>
-	<li>Create a root node whose value is the maximum value in <code>nums</code>.</li>
-	<li>Recursively build the left subtree on the <strong>subarray prefix</strong> to the <strong>left</strong> of the maximum value.</li>
-	<li>Recursively build the right subtree on the <strong>subarray suffix</strong> to the <strong>right</strong> of the maximum value.</li>
-</ol>
-
-<p>Return <em>the <strong>maximum binary tree</strong> built from </em><code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/24/tree1.jpg" style="width: 302px; height: 421px;" />
-<pre>
-<strong>Input:</strong> nums = [3,2,1,6,0,5]
-<strong>Output:</strong> [6,3,5,null,2,0,null,null,1]
-<strong>Explanation:</strong> The recursive calls are as follow:
-- The largest value in [3,2,1,6,0,5] is 6. Left prefix is [3,2,1] and right suffix is [0,5].
-    - The largest value in [3,2,1] is 3. Left prefix is [] and right suffix is [2,1].
-        - Empty array, so no child.
-        - The largest value in [2,1] is 2. Left prefix is [] and right suffix is [1].
-            - Empty array, so no child.
-            - Only one element, so child is a node with value 1.
-    - The largest value in [0,5] is 5. Left prefix is [0] and right suffix is [].
-        - Only one element, so child is a node with value 0.
-        - Empty array, so no child.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/24/tree2.jpg" style="width: 182px; height: 301px;" />
-<pre>
-<strong>Input:</strong> nums = [3,2,1]
-<strong>Output:</strong> [3,null,2,null,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
-	<li>All integers in <code>nums</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Maximum Binary Tree II](../maximum-binary-tree-ii) (Medium)
diff --git a/problems/maximum-binary-tree/maximum_binary_tree.go b/problems/maximum-binary-tree/maximum_binary_tree.go
deleted file mode 100644
index 9de3051a4..000000000
--- a/problems/maximum-binary-tree/maximum_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem654
diff --git a/problems/maximum-binary-tree/maximum_binary_tree_test.go b/problems/maximum-binary-tree/maximum_binary_tree_test.go
deleted file mode 100644
index 9de3051a4..000000000
--- a/problems/maximum-binary-tree/maximum_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem654
diff --git a/problems/maximum-building-height/README.md b/problems/maximum-building-height/README.md
deleted file mode 100644
index 00f21bae3..000000000
--- a/problems/maximum-building-height/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-substring-of-all-vowels-in-order "Longest Substring Of All Vowels in Order")
-　　　　　　　　　　　　　　　　
-[Next >](../league-statistics "League Statistics")
-
-## [1840. Maximum Building Height (Hard)](https://leetcode.com/problems/maximum-building-height "最高建筑高度")
-
-<p>You want to build <code>n</code> new buildings in a city. The new buildings will be built in a line and are labeled from <code>1</code> to <code>n</code>.</p>
-
-<p>However, there are city restrictions on the heights of the new buildings:</p>
-
-<ul>
-	<li>The height of each building must be a non-negative integer.</li>
-	<li>The height of the first building <strong>must</strong> be <code>0</code>.</li>
-	<li>The height difference between any two adjacent buildings <strong>cannot exceed</strong> <code>1</code>.</li>
-</ul>
-
-<p>Additionally, there are city restrictions on the maximum height of specific buildings. These restrictions are given as a 2D integer array <code>restrictions</code> where <code>restrictions[i] = [id<sub>i</sub>, maxHeight<sub>i</sub>]</code> indicates that building <code>id<sub>i</sub></code> must have a height <strong>less than or equal to</strong> <code>maxHeight<sub>i</sub></code>.</p>
-
-<p>It is guaranteed that each building will appear <strong>at most once</strong> in <code>restrictions</code>, and building <code>1</code> will <strong>not</strong> be in <code>restrictions</code>.</p>
-
-<p>Return <em>the <strong>maximum possible height</strong> of the <strong>tallest</strong> building</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/ic236-q4-ex1-1.png" style="width: 400px; height: 253px;" />
-<pre>
-<strong>Input:</strong> n = 5, restrictions = [[2,1],[4,1]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The green area in the image indicates the maximum allowed height for each building.
-We can build the buildings with heights [0,1,2,1,2], and the tallest building has a height of 2.</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/ic236-q4-ex2.png" style="width: 500px; height: 269px;" />
-<pre>
-<strong>Input:</strong> n = 6, restrictions = []
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The green area in the image indicates the maximum allowed height for each building.
-We can build the buildings with heights [0,1,2,3,4,5], and the tallest building has a height of 5.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/ic236-q4-ex3.png" style="width: 500px; height: 187px;" />
-<pre>
-<strong>Input:</strong> n = 10, restrictions = [[5,3],[2,5],[7,4],[10,3]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The green area in the image indicates the maximum allowed height for each building.
-We can build the buildings with heights [0,1,2,3,3,4,4,5,4,3], and the tallest building has a height of 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= restrictions.length &lt;= min(n - 1, 10<sup>5</sup>)</code></li>
-	<li><code>2 &lt;= id<sub>i</sub> &lt;= n</code></li>
-	<li><code>id<sub>i</sub></code>&nbsp;is <strong>unique</strong>.</li>
-	<li><code>0 &lt;= maxHeight<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is it possible to find the max height if given the height range of a particular building?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can find the height range of a restricted building by doing 2 passes from the left and right.
-</details>
diff --git a/problems/maximum-candies-you-can-get-from-boxes/README.md b/problems/maximum-candies-you-can-get-from-boxes/README.md
deleted file mode 100644
index d714a6c5d..000000000
--- a/problems/maximum-candies-you-can-get-from-boxes/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-occurrences-of-a-substring "Maximum Number of Occurrences of a Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../replace-elements-with-greatest-element-on-right-side "Replace Elements with Greatest Element on Right Side")
-
-## [1298. Maximum Candies You Can Get from Boxes (Hard)](https://leetcode.com/problems/maximum-candies-you-can-get-from-boxes "你能从盒子里获得的最大糖果数")
-
-<p>You have <code>n</code> boxes labeled from <code>0</code> to <code>n - 1</code>. You are given four arrays: <code>status</code>, <code>candies</code>, <code>keys</code>, and <code>containedBoxes</code> where:</p>
-
-<ul>
-	<li><code>status[i]</code> is <code>1</code> if the <code>i<sup>th</sup></code> box is open and <code>0</code> if the <code>i<sup>th</sup></code> box is closed,</li>
-	<li><code>candies[i]</code> is the number of candies in the <code>i<sup>th</sup></code> box,</li>
-	<li><code>keys[i]</code> is a list of the labels of the boxes you can open after opening the <code>i<sup>th</sup></code> box.</li>
-	<li><code>containedBoxes[i]</code> is a list of the boxes you found inside the <code>i<sup>th</sup></code> box.</li>
-</ul>
-
-<p>You are given an integer array <code>initialBoxes</code> that contains the labels of the boxes you initially have. You can take all the candies in <strong>any open box</strong> and you can use the keys in it to open new boxes and you also can use the boxes you find in it.</p>
-
-<p>Return <em>the maximum number of candies you can get following the rules above</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> status = [1,0,1,0], candies = [7,5,4,100], keys = [[],[],[1],[]], containedBoxes = [[1,2],[3],[],[]], initialBoxes = [0]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> You will be initially given box 0. You will find 7 candies in it and boxes 1 and 2.
-Box 1 is closed and you do not have a key for it so you will open box 2. You will find 4 candies and a key to box 1 in box 2.
-In box 1, you will find 5 candies and box 3 but you will not find a key to box 3 so box 3 will remain closed.
-Total number of candies collected = 7 + 4 + 5 = 16 candy.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> status = [1,0,0,0,0,0], candies = [1,1,1,1,1,1], keys = [[1,2,3,4,5],[],[],[],[],[]], containedBoxes = [[1,2,3,4,5],[],[],[],[],[]], initialBoxes = [0]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> You have initially box 0. Opening it you can find boxes 1,2,3,4 and 5 and their keys.
-The total number of candies will be 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == status.length == candies.length == keys.length == containedBoxes.length</code></li>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>status[i]</code> is either <code>0</code> or <code>1</code>.</li>
-	<li><code>1 &lt;= candies[i] &lt;= 1000</code></li>
-	<li><code>0 &lt;= keys[i].length &lt;= n</code></li>
-	<li><code>0 &lt;= keys[i][j] &lt; n</code></li>
-	<li>All values of <code>keys[i]</code> are <strong>unique</strong>.</li>
-	<li><code>0 &lt;= containedBoxes[i].length &lt;= n</code></li>
-	<li><code>0 &lt;= containedBoxes[i][j] &lt; n</code></li>
-	<li>All values of <code>containedBoxes[i]</code> are unique.</li>
-	<li>Each box is contained in one box at most.</li>
-	<li><code>0 &lt;= initialBoxes.length &lt;= n</code></li>
-	<li><code>0 &lt;= initialBoxes[i] &lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use Breadth First Search (BFS) to traverse all possible boxes you can open. Only push to the queue the boxes the you have with their keys.
-</details>
diff --git a/problems/maximum-compatibility-score-sum/README.md b/problems/maximum-compatibility-score-sum/README.md
deleted file mode 100644
index f0aa7c7a8..000000000
--- a/problems/maximum-compatibility-score-sum/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-number-after-mutating-substring "Largest Number After Mutating Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-duplicate-folders-in-system "Delete Duplicate Folders in System")
-
-## [1947. Maximum Compatibility Score Sum (Medium)](https://leetcode.com/problems/maximum-compatibility-score-sum "最大兼容性评分和")
-
-<p>There is a survey that consists of <code>n</code> questions where each question&#39;s answer is either <code>0</code> (no) or <code>1</code> (yes).</p>
-
-<p>The survey was given to <code>m</code> students numbered from <code>0</code> to <code>m - 1</code> and <code>m</code> mentors numbered from <code>0</code> to <code>m - 1</code>. The answers of the students are represented by a 2D integer array <code>students</code> where <code>students[i]</code> is an integer array that contains the answers of the <code>i<sup>th</sup></code> student (<strong>0-indexed</strong>). The answers of the mentors are represented by a 2D integer array <code>mentors</code> where <code>mentors[j]</code> is an integer array that contains the answers of the <code>j<sup>th</sup></code> mentor (<strong>0-indexed</strong>).</p>
-
-<p>Each student will be assigned to <strong>one</strong> mentor, and each mentor will have <strong>one</strong> student assigned to them. The <strong>compatibility score</strong> of a student-mentor pair is the number of answers that are the same for both the student and the mentor.</p>
-
-<ul>
-	<li>For example, if the student&#39;s answers were <code>[1, <u>0</u>, <u>1</u>]</code> and the mentor&#39;s answers were <code>[0, <u>0</u>, <u>1</u>]</code>, then their compatibility score is 2 because only the second and the third answers are the same.</li>
-</ul>
-
-<p>You are tasked with finding the optimal student-mentor pairings to <strong>maximize</strong> the<strong> sum of the compatibility scores</strong>.</p>
-
-<p>Given <code>students</code> and <code>mentors</code>, return <em>the <strong>maximum compatibility score sum</strong> that can be achieved.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> students = [[1,1,0],[1,0,1],[0,0,1]], mentors = [[1,0,0],[0,0,1],[1,1,0]]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong>&nbsp;We assign students to mentors in the following way:
-- student 0 to mentor 2 with a compatibility score of 3.
-- student 1 to mentor 0 with a compatibility score of 2.
-- student 2 to mentor 1 with a compatibility score of 3.
-The compatibility score sum is 3 + 2 + 3 = 8.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> students = [[0,0],[0,0],[0,0]], mentors = [[1,1],[1,1],[1,1]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The compatibility score of any student-mentor pair is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == students.length == mentors.length</code></li>
-	<li><code>n == students[i].length == mentors[j].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 8</code></li>
-	<li><code>students[i][k]</code> is either <code>0</code> or <code>1</code>.</li>
-	<li><code>mentors[j][k]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Calculate the compatibility score for each student-mentor pair.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try every permutation of students with the original mentors array.
-</details>
diff --git a/problems/maximum-depth-of-binary-tree/README.md b/problems/maximum-depth-of-binary-tree/README.md
deleted file mode 100644
index 7ff9c358c..000000000
--- a/problems/maximum-depth-of-binary-tree/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-zigzag-level-order-traversal "Binary Tree Zigzag Level Order Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-binary-tree-from-preorder-and-inorder-traversal "Construct Binary Tree from Preorder and Inorder Traversal")
-
-## [104. Maximum Depth of Binary Tree (Easy)](https://leetcode.com/problems/maximum-depth-of-binary-tree "二叉树的最大深度")
-
-<p>Given the <code>root</code> of a binary tree, return <em>its maximum depth</em>.</p>
-
-<p>A binary tree&#39;s <strong>maximum depth</strong>&nbsp;is the number of nodes along the longest path from the root node down to the farthest leaf node.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/26/tmp-tree.jpg" style="width: 400px; height: 277px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,null,null,15,7]
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,2]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [0]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Balanced Binary Tree](../balanced-binary-tree) (Easy)
-  1. [Minimum Depth of Binary Tree](../minimum-depth-of-binary-tree) (Easy)
-  1. [Maximum Depth of N-ary Tree](../maximum-depth-of-n-ary-tree) (Easy)
-  1. [Time Needed to Inform All Employees](../time-needed-to-inform-all-employees) (Medium)
diff --git a/problems/maximum-depth-of-binary-tree/maximum_depth_of_binary_tree.go b/problems/maximum-depth-of-binary-tree/maximum_depth_of_binary_tree.go
deleted file mode 100644
index b415d42a2..000000000
--- a/problems/maximum-depth-of-binary-tree/maximum_depth_of_binary_tree.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package problem104
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func maxDepth(root *TreeNode) int {
-	if root == nil {
-		return 0
-	}
-	l := maxDepth(root.Left) + 1
-	r := maxDepth(root.Right) + 1
-	if l > r {
-		return l
-	}
-	return r
-}
diff --git a/problems/maximum-depth-of-binary-tree/maximum_depth_of_binary_tree_test.go b/problems/maximum-depth-of-binary-tree/maximum_depth_of_binary_tree_test.go
deleted file mode 100644
index ad32798aa..000000000
--- a/problems/maximum-depth-of-binary-tree/maximum_depth_of_binary_tree_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem104
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMaxDepth(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 9, 20, kit.NULL, kit.NULL, 15, 7},
-			want: 3,
-		},
-		{
-			in:   []int{1, 2, 3, kit.NULL, 5, 6},
-			want: 3,
-		},
-		{
-			in:   []int{1, 2, kit.NULL, kit.NULL, 5},
-			want: 3,
-		},
-		{
-			in:   []int{1, kit.NULL, 3, kit.NULL, 5},
-			want: 3,
-		},
-	}
-	for _, tt := range tests {
-		got := maxDepth(kit.SliceInt2TreeNode(tt.in))
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/maximum-depth-of-n-ary-tree/README.md b/problems/maximum-depth-of-n-ary-tree/README.md
deleted file mode 100644
index 77172cb21..000000000
--- a/problems/maximum-depth-of-n-ary-tree/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../logical-or-of-two-binary-grids-represented-as-quad-trees "Logical OR of Two Binary Grids Represented as Quad-Trees")
-　　　　　　　　　　　　　　　　
-[Next >](../subarray-sum-equals-k "Subarray Sum Equals K")
-
-## [559. Maximum Depth of N-ary Tree (Easy)](https://leetcode.com/problems/maximum-depth-of-n-ary-tree "N 叉树的最大深度")
-
-<p>Given a n-ary tree, find its maximum depth.</p>
-
-<p>The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.</p>
-
-<p><em>Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img src="https://assets.leetcode.com/uploads/2018/10/12/narytreeexample.png" style="width: 100%; max-width: 300px;" /></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,3,2,4,null,5,6]
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/11/08/sample_4_964.png" style="width: 296px; height: 241px;" /></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
-<strong>Output:</strong> 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The total number of nodes is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li>The depth of the n-ary tree is less than or equal to <code>1000</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Maximum Depth of Binary Tree](../maximum-depth-of-binary-tree) (Easy)
-  1. [The Time When the Network Becomes Idle](../the-time-when-the-network-becomes-idle) (Medium)
diff --git a/problems/maximum-depth-of-n-ary-tree/maximum_depth_of_n_ary_tree.go b/problems/maximum-depth-of-n-ary-tree/maximum_depth_of_n_ary_tree.go
deleted file mode 100644
index 1e6e2f5d8..000000000
--- a/problems/maximum-depth-of-n-ary-tree/maximum_depth_of_n_ary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem559
diff --git a/problems/maximum-depth-of-n-ary-tree/maximum_depth_of_n_ary_tree.py b/problems/maximum-depth-of-n-ary-tree/maximum_depth_of_n_ary_tree.py
deleted file mode 100755
index 47fb17228..000000000
--- a/problems/maximum-depth-of-n-ary-tree/maximum_depth_of_n_ary_tree.py
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a Node.
-class Node:
-    def __init__(self, val, children):
-        self.val = val
-        self.children = children
-"""
-class Solution:
-    def maxDepth(self, root: 'Node') -> int:
-        
\ No newline at end of file
diff --git a/problems/maximum-depth-of-n-ary-tree/maximum_depth_of_n_ary_tree_test.go b/problems/maximum-depth-of-n-ary-tree/maximum_depth_of_n_ary_tree_test.go
deleted file mode 100644
index 1e6e2f5d8..000000000
--- a/problems/maximum-depth-of-n-ary-tree/maximum_depth_of_n_ary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem559
diff --git a/problems/maximum-difference-between-increasing-elements/README.md b/problems/maximum-difference-between-increasing-elements/README.md
deleted file mode 100644
index 30cb293a1..000000000
--- a/problems/maximum-difference-between-increasing-elements/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../average-height-of-buildings-in-each-segment "Average Height of Buildings in Each Segment")
-　　　　　　　　　　　　　　　　
-[Next >](../grid-game "Grid Game")
-
-## [2016. Maximum Difference Between Increasing Elements (Easy)](https://leetcode.com/problems/maximum-difference-between-increasing-elements "增量元素之间的最大差值")
-
-<p>Given a <strong>0-indexed</strong> integer array <code>nums</code> of size <code>n</code>, find the <strong>maximum difference</strong> between <code>nums[i]</code> and <code>nums[j]</code> (i.e., <code>nums[j] - nums[i]</code>), such that <code>0 &lt;= i &lt; j &lt; n</code> and <code>nums[i] &lt; nums[j]</code>.</p>
-
-<p>Return <em>the <strong>maximum difference</strong>. </em>If no such <code>i</code> and <code>j</code> exists, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,<strong><u>1</u></strong>,<strong><u>5</u></strong>,4]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-The maximum difference occurs with i = 1 and j = 2, nums[j] - nums[i] = 5 - 1 = 4.
-Note that with i = 1 and j = 0, the difference nums[j] - nums[i] = 7 - 1 = 6, but i &gt; j, so it is not valid.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,4,3,2]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>
-There is no i and j such that i &lt; j and nums[i] &lt; nums[j].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [<strong><u>1</u></strong>,5,2,<strong><u>10</u></strong>]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong>
-The maximum difference occurs with i = 0 and j = 3, nums[j] - nums[i] = 10 - 1 = 9.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>2 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could you keep track of the minimum element visited while traversing?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We have a potential candidate for the answer if the prefix min is lesser than nums[i].
-</details>
diff --git a/problems/maximum-difference-between-node-and-ancestor/README.md b/problems/maximum-difference-between-node-and-ancestor/README.md
deleted file mode 100644
index d8ad9af3b..000000000
--- a/problems/maximum-difference-between-node-and-ancestor/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../divisor-game "Divisor Game")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-arithmetic-subsequence "Longest Arithmetic Subsequence")
-
-## [1026. Maximum Difference Between Node and Ancestor (Medium)](https://leetcode.com/problems/maximum-difference-between-node-and-ancestor "节点与其祖先之间的最大差值")
-
-<p>Given the <code>root</code> of a binary tree, find the maximum value <code>v</code> for which there exist <strong>different</strong> nodes <code>a</code> and <code>b</code> where <code>v = |a.val - b.val|</code> and <code>a</code> is an ancestor of <code>b</code>.</p>
-
-<p>A node <code>a</code> is an ancestor of <code>b</code> if either: any child of <code>a</code> is equal to <code>b</code>&nbsp;or any child of <code>a</code> is an ancestor of <code>b</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/09/tmp-tree.jpg" style="width: 400px; height: 390px;" />
-<pre>
-<strong>Input:</strong> root = [8,3,10,1,6,null,14,null,null,4,7,13]
-<strong>Output:</strong> 7
-<strong>Explanation: </strong>We have various ancestor-node differences, some of which are given below :
-|8 - 3| = 5
-|3 - 7| = 4
-|8 - 1| = 7
-|10 - 13| = 3
-Among all possible differences, the maximum value of 7 is obtained by |8 - 1| = 7.</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/09/tmp-tree-1.jpg" style="width: 250px; height: 349px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2,null,0,3]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[2, 5000]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each subtree, find the minimum value and maximum value of its descendants.
-</details>
diff --git a/problems/maximum-distance-between-a-pair-of-values/README.md b/problems/maximum-distance-between-a-pair-of-values/README.md
deleted file mode 100644
index e88895f23..000000000
--- a/problems/maximum-distance-between-a-pair-of-values/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-population-year "Maximum Population Year")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-subarray-min-product "Maximum Subarray Min-Product")
-
-## [1855. Maximum Distance Between a Pair of Values (Medium)](https://leetcode.com/problems/maximum-distance-between-a-pair-of-values "下标对中的最大距离")
-
-<p>You are given two <strong>non-increasing 0-indexed </strong>integer arrays <code>nums1</code>​​​​​​ and <code>nums2</code>​​​​​​.</p>
-
-<p>A pair of indices <code>(i, j)</code>, where <code>0 &lt;= i &lt; nums1.length</code> and <code>0 &lt;= j &lt; nums2.length</code>, is <strong>valid</strong> if both <code>i &lt;= j</code> and <code>nums1[i] &lt;= nums2[j]</code>. The <strong>distance</strong> of the pair is <code>j - i</code>​​​​.</p>
-
-<p>Return <em>the <strong>maximum distance</strong> of any <strong>valid</strong> pair </em><code>(i, j)</code><em>. If there are no valid pairs, return </em><code>0</code>.</p>
-
-<p>An array <code>arr</code> is <strong>non-increasing</strong> if <code>arr[i-1] &gt;= arr[i]</code> for every <code>1 &lt;= i &lt; arr.length</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [55,30,5,4,2], nums2 = [100,20,10,10,5]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The valid pairs are (0,0), (2,2), (2,3), (2,4), (3,3), (3,4), and (4,4).
-The maximum distance is 2 with pair (2,4).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [2,2,2], nums2 = [10,10,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The valid pairs are (0,0), (0,1), and (1,1).
-The maximum distance is 1 with pair (0,1).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [30,29,19,5], nums2 = [25,25,25,25,25]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The valid pairs are (2,2), (2,3), (2,4), (3,3), and (3,4).
-The maximum distance is 2 with pair (2,4).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums1[i], nums2[j] &lt;= 10<sup>5</sup></code></li>
-	<li>Both <code>nums1</code> and <code>nums2</code> are <strong>non-increasing</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since both arrays are sorted in a non-increasing way this means that for each value in the first array. We can find the farthest value smaller than it using binary search.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-There is another solution using a two pointers approach since the first array is non-increasing the farthest j such that nums2[j] ≥ nums1[i] is at least as far as the farthest j such that nums2[j] ≥ nums1[i-1]
-</details>
diff --git a/problems/maximum-distance-in-arrays/README.md b/problems/maximum-distance-in-arrays/README.md
deleted file mode 100644
index 4190a9404..000000000
--- a/problems/maximum-distance-in-arrays/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-one-row-to-tree "Add One Row to Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-factorization "Minimum Factorization")
-
-## [624. Maximum Distance in Arrays (Medium)](https://leetcode.com/problems/maximum-distance-in-arrays "数组列表中的最大距离")
-
-<p>
-Given <code>m</code> arrays, and each array is sorted in ascending order. Now you can pick up two integers from two different arrays (each array picks one) and calculate the distance. We define the distance between two integers <code>a</code> and <code>b</code> to be their absolute difference <code>|a-b|</code>. Your task is to find the maximum distance.
-</p>
-
-<p><b>Example 1:</b><br />
-<pre><b>Input:</b> 
-[[1,2,3],
- [4,5],
- [1,2,3]]
-<b>Output:</b> 4
-<b>Explanation:</b> 
-One way to reach the maximum distance 4 is to pick 1 in the first or third array and pick 5 in the second array.
-</pre>
-</p>
-	
-<p><b>Note:</b><br>
-<ol>
-<li>Each given array will have at least 1 number. There will be at least two non-empty arrays.</li>
-<li>The total number of the integers in <b>all</b> the <code>m</code> arrays will be in the range of [2, 10000].</li>
-<li>The integers in the <code>m</code> arrays will be in the range of [-10000, 10000].</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
diff --git a/problems/maximum-distance-in-arrays/maximum_distance_in_arrays.go b/problems/maximum-distance-in-arrays/maximum_distance_in_arrays.go
deleted file mode 100644
index 42e642e60..000000000
--- a/problems/maximum-distance-in-arrays/maximum_distance_in_arrays.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem624
diff --git a/problems/maximum-distance-in-arrays/maximum_distance_in_arrays_test.go b/problems/maximum-distance-in-arrays/maximum_distance_in_arrays_test.go
deleted file mode 100644
index 42e642e60..000000000
--- a/problems/maximum-distance-in-arrays/maximum_distance_in_arrays_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem624
diff --git a/problems/maximum-earnings-from-taxi/README.md b/problems/maximum-earnings-from-taxi/README.md
deleted file mode 100644
index 94e38354e..000000000
--- a/problems/maximum-earnings-from-taxi/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-original-array-from-doubled-array "Find Original Array From Doubled Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-operations-to-make-array-continuous "Minimum Number of Operations to Make Array Continuous")
-
-## [2008. Maximum Earnings From Taxi (Medium)](https://leetcode.com/problems/maximum-earnings-from-taxi "出租车的最大盈利")
-
-<p>There are <code>n</code> points on a road you are driving your taxi on. The <code>n</code> points on the road are labeled from <code>1</code> to <code>n</code> in the direction you are going, and you want to drive from point <code>1</code> to point <code>n</code> to make money by picking up passengers. You cannot change the direction of the taxi.</p>
-
-<p>The passengers are represented by a <strong>0-indexed</strong> 2D integer array <code>rides</code>, where <code>rides[i] = [start<sub>i</sub>, end<sub>i</sub>, tip<sub>i</sub>]</code> denotes the <code>i<sup>th</sup></code> passenger requesting a ride from point <code>start<sub>i</sub></code> to point <code>end<sub>i</sub></code> who is willing to give a <code>tip<sub>i</sub></code> dollar tip.</p>
-
-<p>For<strong> each </strong>passenger <code>i</code> you pick up, you <strong>earn</strong> <code>end<sub>i</sub> - start<sub>i</sub> + tip<sub>i</sub></code> dollars. You may only drive <b>at most one </b>passenger at a time.</p>
-
-<p>Given <code>n</code> and <code>rides</code>, return <em>the <strong>maximum</strong> number of dollars you can earn by picking up the passengers optimally.</em></p>
-
-<p><strong>Note:</strong> You may drop off a passenger and pick up a different passenger at the same point.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, rides = [<u>[2,5,4]</u>,[1,5,1]]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> We can pick up passenger 0 to earn 5 - 2 + 4 = 7 dollars.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 20, rides = [[1,6,1],<u>[3,10,2]</u>,<u>[10,12,3]</u>,[11,12,2],[12,15,2],<u>[13,18,1]</u>]
-<strong>Output:</strong> 20
-<strong>Explanation:</strong> We will pick up the following passengers:
-- Drive passenger 1 from point 3 to point 10 for a profit of 10 - 3 + 2 = 9 dollars.
-- Drive passenger 2 from point 10 to point 12 for a profit of 12 - 10 + 3 = 5 dollars.
-- Drive passenger 5 from point 13 to point 18 for a profit of 18 - 13 + 1 = 6 dollars.
-We earn 9 + 5 + 6 = 20 dollars in total.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= rides.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>rides[i].length == 3</code></li>
-	<li><code>1 &lt;= start<sub>i</sub> &lt; end<sub>i</sub> &lt;= n</code></li>
-	<li><code>1 &lt;= tip<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we sort the array to help us solve the problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can use dynamic programming to keep track of the maximum at each position.
-</details>
diff --git a/problems/maximum-element-after-decreasing-and-rearranging/README.md b/problems/maximum-element-after-decreasing-and-rearranging/README.md
deleted file mode 100644
index b3c3ef248..000000000
--- a/problems/maximum-element-after-decreasing-and-rearranging/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../seat-reservation-manager "Seat Reservation Manager")
-　　　　　　　　　　　　　　　　
-[Next >](../closest-room "Closest Room")
-
-## [1846. Maximum Element After Decreasing and Rearranging (Medium)](https://leetcode.com/problems/maximum-element-after-decreasing-and-rearranging "减小和重新排列数组后的最大元素")
-
-<p>You are given an array of positive integers <code>arr</code>. Perform some operations (possibly none) on <code>arr</code> so that it satisfies these conditions:</p>
-
-<ul>
-	<li>The value of the <strong>first</strong> element in <code>arr</code> must be <code>1</code>.</li>
-	<li>The absolute difference between any 2 adjacent elements must be <strong>less than or equal to </strong><code>1</code>. In other words, <code>abs(arr[i] - arr[i - 1]) &lt;= 1</code> for each <code>i</code> where <code>1 &lt;= i &lt; arr.length</code> (<strong>0-indexed</strong>). <code>abs(x)</code> is the absolute value of <code>x</code>.</li>
-</ul>
-
-<p>There are 2 types of operations that you can perform any number of times:</p>
-
-<ul>
-	<li><strong>Decrease</strong> the value of any element of <code>arr</code> to a <strong>smaller positive integer</strong>.</li>
-	<li><strong>Rearrange</strong> the elements of <code>arr</code> to be in any order.</li>
-</ul>
-
-<p>Return <em>the <strong>maximum</strong> possible value of an element in </em><code>arr</code><em> after performing the operations to satisfy the conditions</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,2,1,2,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-We can satisfy the conditions by rearranging <code>arr</code> so it becomes <code>[1,2,2,2,1]</code>.
-The largest element in <code>arr</code> is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [100,1,1000]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-One possible way to satisfy the conditions is by doing the following:
-1. Rearrange <code>arr</code> so it becomes <code>[1,100,1000]</code>.
-2. Decrease the value of the second element to 2.
-3. Decrease the value of the third element to 3.
-Now <code>arr = [1,2,3], which </code>satisfies the conditions.
-The largest element in <code>arr is 3.</code>
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4,5]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The array already satisfies the conditions, and the largest element is 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the Array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Decrement each element to the largest integer that satisfies the conditions.
-</details>
diff --git a/problems/maximum-employees-to-be-invited-to-a-meeting/README.md b/problems/maximum-employees-to-be-invited-to-a-meeting/README.md
deleted file mode 100644
index b593c81e1..000000000
--- a/problems/maximum-employees-to-be-invited-to-a-meeting/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../destroying-asteroids "Destroying Asteroids")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-all-ones-with-row-and-column-flips "Remove All Ones With Row and Column Flips")
-
-## [2127. Maximum Employees to Be Invited to a Meeting (Hard)](https://leetcode.com/problems/maximum-employees-to-be-invited-to-a-meeting "参加会议的最多员工数")
-
-<p>A company is organizing a meeting and has a list of <code>n</code> employees, waiting to be invited. They have arranged for a large <strong>circular</strong> table, capable of seating <strong>any number</strong> of employees.</p>
-
-<p>The employees are numbered from <code>0</code> to <code>n - 1</code>. Each employee has a <strong>favorite</strong> person and they will attend the meeting <strong>only if</strong> they can sit next to their favorite person at the table. The favorite person of an employee is <strong>not</strong> themself.</p>
-
-<p>Given a <strong>0-indexed</strong> integer array <code>favorite</code>, where <code>favorite[i]</code> denotes the favorite person of the <code>i<sup>th</sup></code> employee, return <em>the <strong>maximum number of employees</strong> that can be invited to the meeting</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/14/ex1.png" style="width: 236px; height: 195px;" />
-<pre>
-<strong>Input:</strong> favorite = [2,2,1,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-The above figure shows how the company can invite employees 0, 1, and 2, and seat them at the round table.
-All employees cannot be invited because employee 2 cannot sit beside employees 0, 1, and 3, simultaneously.
-Note that the company can also invite employees 1, 2, and 3, and give them their desired seats.
-The maximum number of employees that can be invited to the meeting is 3. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> favorite = [1,2,0]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-Each employee is the favorite person of at least one other employee, and the only way the company can invite them is if they invite every employee.
-The seating arrangement will be the same as that in the figure given in example 1:
-- Employee 0 will sit between employees 2 and 1.
-- Employee 1 will sit between employees 0 and 2.
-- Employee 2 will sit between employees 1 and 0.
-The maximum number of employees that can be invited to the meeting is 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/14/ex2.png" style="width: 219px; height: 220px;" />
-<pre>
-<strong>Input:</strong> favorite = [3,0,1,4,1]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-The above figure shows how the company will invite employees 0, 1, 3, and 4, and seat them at the round table.
-Employee 2 cannot be invited because the two spots next to their favorite employee 1 are taken.
-So the company leaves them out of the meeting.
-The maximum number of employees that can be invited to the meeting is 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == favorite.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= favorite[i] &lt;=&nbsp;n - 1</code></li>
-	<li><code>favorite[i] != i</code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-From the given array favorite, create a graph where for every index i, there is a directed edge from favorite[i] to i. The graph will be a combination of cycles and chains of acyclic edges. Now, what are the ways in which we can choose employees to sit at the table?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The first way by which we can choose employees is by selecting a cycle of the graph. It can be proven that in this case, the employees that do not lie in the cycle can never be seated at the table.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The second way is by combining acyclic chains. At most two chains can be combined by a cycle of length 2, where each chain ends on one of the employees in the cycle.
-</details>
diff --git a/problems/maximum-equal-frequency/README.md b/problems/maximum-equal-frequency/README.md
deleted file mode 100644
index 8657085d5..000000000
--- a/problems/maximum-equal-frequency/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../dice-roll-simulation "Dice Roll Simulation")
-　　　　　　　　　　　　　　　　
-[Next >](../report-contiguous-dates "Report Contiguous Dates")
-
-## [1224. Maximum Equal Frequency (Hard)](https://leetcode.com/problems/maximum-equal-frequency "最大相等频率")
-
-<p>Given an array <code>nums</code>&nbsp;of positive integers, return the longest possible length of an array prefix of <code>nums</code>, such that it is possible to remove <strong>exactly one</strong> element from this prefix so that every number that has appeared in it will have the same number of occurrences.</p>
-
-<p>If after removing one element there are no remaining elements, it&#39;s still considered that every appeared number has the same number of ocurrences (0).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,1,1,5,3,3,5]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> For the subarray [2,2,1,1,5,3,3] of length 7, if we remove nums[4]=5, we will get [2,2,1,1,3,3], so that each number will appear exactly twice.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,2,2,2,3,3,3,4,4,4,5]
-<strong>Output:</strong> 13
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,2,2,2]
-<strong>Output:</strong> 5
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,2,8,9,3,8,1,5,2,3,7,6]
-<strong>Output:</strong> 8
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep track of the min and max frequencies.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The number to be eliminated must have a frequency of 1, same as the others or the same +1.
-</details>
diff --git a/problems/maximum-erasure-value/README.md b/problems/maximum-erasure-value/README.md
deleted file mode 100644
index 212f859cf..000000000
--- a/problems/maximum-erasure-value/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reformat-phone-number "Reformat Phone Number")
-　　　　　　　　　　　　　　　　
-[Next >](../jump-game-vi "Jump Game VI")
-
-## [1695. Maximum Erasure Value (Medium)](https://leetcode.com/problems/maximum-erasure-value "删除子数组的最大得分")
-
-<p>You are given an array of positive integers <code>nums</code> and want to erase a subarray containing&nbsp;<strong>unique elements</strong>. The <strong>score</strong> you get by erasing the subarray is equal to the <strong>sum</strong> of its elements.</p>
-
-<p>Return <em>the <strong>maximum score</strong> you can get by erasing <strong>exactly one</strong> subarray.</em></p>
-
-<p>An array <code>b</code> is called to be a <span class="tex-font-style-it">subarray</span> of <code>a</code> if it forms a contiguous subsequence of <code>a</code>, that is, if it is equal to <code>a[l],a[l+1],...,a[r]</code> for some <code>(l,r)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,4,5,6]
-<strong>Output:</strong> 17
-<strong>Explanation:</strong> The optimal subarray here is [2,4,5,6].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,2,1,2,5,2,1,2,5]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> The optimal subarray here is [5,2,1] or [1,2,5].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The main point here is for the subarray to contain unique elements for each index. Only the first subarrays starting from that index have unique elements.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-This can be solved using the two pointers technique
-</details>
diff --git a/problems/maximum-font-to-fit-a-sentence-in-a-screen/README.md b/problems/maximum-font-to-fit-a-sentence-in-a-screen/README.md
deleted file mode 100644
index fdb3b26d9..000000000
--- a/problems/maximum-font-to-fit-a-sentence-in-a-screen/README.md
+++ /dev/null
@@ -1,26 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-subtrees-with-max-distance-between-cities "Count Subtrees With Max Distance Between Cities")
-　　　　　　　　　　　　　　　　
-[Next >](../mean-of-array-after-removing-some-elements "Mean of Array After Removing Some Elements")
-
-## [1618. Maximum Font to Fit a Sentence in a Screen (Medium)](https://leetcode.com/problems/maximum-font-to-fit-a-sentence-in-a-screen "找出适应屏幕的最大字号")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use <i>binary search</i>  to find the last valid font.
-</details>
diff --git a/problems/maximum-frequency-stack/README.md b/problems/maximum-frequency-stack/README.md
deleted file mode 100644
index 03b442b2d..000000000
--- a/problems/maximum-frequency-stack/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-possible-full-binary-trees "All Possible Full Binary Trees")
-　　　　　　　　　　　　　　　　
-[Next >](../monotonic-array "Monotonic Array")
-
-## [895. Maximum Frequency Stack (Hard)](https://leetcode.com/problems/maximum-frequency-stack "最大频率栈")
-
-<p>Design a stack-like data structure to push elements to the stack and pop the most frequent element from the stack.</p>
-
-<p>Implement the <code>FreqStack</code> class:</p>
-
-<ul>
-	<li><code>FreqStack()</code> constructs an empty frequency stack.</li>
-	<li><code>void push(int val)</code> pushes an integer <code>val</code> onto the top of the stack.</li>
-	<li><code>int pop()</code> removes and returns the most frequent element in the stack.
-	<ul>
-		<li>If there is a tie for the most frequent element, the element closest to the stack&#39;s top is removed and returned.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;FreqStack&quot;, &quot;push&quot;, &quot;push&quot;, &quot;push&quot;, &quot;push&quot;, &quot;push&quot;, &quot;push&quot;, &quot;pop&quot;, &quot;pop&quot;, &quot;pop&quot;, &quot;pop&quot;]
-[[], [5], [7], [5], [7], [4], [5], [], [], [], []]
-<strong>Output</strong>
-[null, null, null, null, null, null, null, 5, 7, 5, 4]
-
-<strong>Explanation</strong>
-FreqStack freqStack = new FreqStack();
-freqStack.push(5); // The stack is [5]
-freqStack.push(7); // The stack is [5,7]
-freqStack.push(5); // The stack is [5,7,5]
-freqStack.push(7); // The stack is [5,7,5,7]
-freqStack.push(4); // The stack is [5,7,5,7,4]
-freqStack.push(5); // The stack is [5,7,5,7,4,5]
-freqStack.pop();   // return 5, as 5 is the most frequent. The stack becomes [5,7,5,7,4].
-freqStack.pop();   // return 7, as 5 and 7 is the most frequent, but 7 is closest to the top. The stack becomes [5,7,5,4].
-freqStack.pop();   // return 5, as 5 is the most frequent. The stack becomes [5,7,4].
-freqStack.pop();   // return 4, as 4, 5 and 7 is the most frequent, but 4 is closest to the top. The stack becomes [5,7].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= val &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>2 * 10<sup>4</sup></code> calls will be made to <code>push</code> and <code>pop</code>.</li>
-	<li>It is guaranteed that there will be at least one element in the stack before calling <code>pop</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
diff --git a/problems/maximum-frequency-stack/maximum_frequency_stack.go b/problems/maximum-frequency-stack/maximum_frequency_stack.go
deleted file mode 100644
index e88294255..000000000
--- a/problems/maximum-frequency-stack/maximum_frequency_stack.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem895
diff --git a/problems/maximum-frequency-stack/maximum_frequency_stack_test.go b/problems/maximum-frequency-stack/maximum_frequency_stack_test.go
deleted file mode 100644
index e88294255..000000000
--- a/problems/maximum-frequency-stack/maximum_frequency_stack_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem895
diff --git a/problems/maximum-fruits-harvested-after-at-most-k-steps/README.md b/problems/maximum-fruits-harvested-after-at-most-k-steps/README.md
deleted file mode 100644
index 997d2537c..000000000
--- a/problems/maximum-fruits-harvested-after-at-most-k-steps/README.md
+++ /dev/null
@@ -1,99 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../watering-plants-ii "Watering Plants II")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-unique-flavors-after-sharing-k-candies "Number of Unique Flavors After Sharing K Candies")
-
-## [2106. Maximum Fruits Harvested After at Most K Steps (Hard)](https://leetcode.com/problems/maximum-fruits-harvested-after-at-most-k-steps "摘水果")
-
-<p>Fruits are available at some positions on an infinite x-axis. You are given a 2D integer array <code>fruits</code> where <code>fruits[i] = [position<sub>i</sub>, amount<sub>i</sub>]</code> depicts <code>amount<sub>i</sub></code> fruits at the position <code>position<sub>i</sub></code>. <code>fruits</code> is already <strong>sorted</strong> by <code>position<sub>i</sub></code> in <strong>ascending order</strong>, and each <code>position<sub>i</sub></code> is <strong>unique</strong>.</p>
-
-<p>You are also given an integer <code>startPos</code> and an integer <code>k</code>. Initially, you are at the position <code>startPos</code>. From any position, you can either walk to the <strong>left or right</strong>. It takes <strong>one step</strong> to move <strong>one unit</strong> on the x-axis, and you can walk <strong>at most</strong> <code>k</code> steps in total. For every position you reach, you harvest all the fruits at that position, and the fruits will disappear from that position.</p>
-
-<p>Return <em>the <strong>maximum total number</strong> of fruits you can harvest</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/21/1.png" style="width: 472px; height: 115px;" />
-<pre>
-<strong>Input:</strong> fruits = [[2,8],[6,3],[8,6]], startPos = 5, k = 4
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> 
-The optimal way is to:
-- Move right to position 6 and harvest 3 fruits
-- Move right to position 8 and harvest 6 fruits
-You moved 3 steps and harvested 3 + 6 = 9 fruits in total.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/21/2.png" style="width: 512px; height: 129px;" />
-<pre>
-<strong>Input:</strong> fruits = [[0,9],[4,1],[5,7],[6,2],[7,4],[10,9]], startPos = 5, k = 4
-<strong>Output:</strong> 14
-<strong>Explanation:</strong> 
-You can move at most k = 4 steps, so you cannot reach position 0 nor 10.
-The optimal way is to:
-- Harvest the 7 fruits at the starting position 5
-- Move left to position 4 and harvest 1 fruit
-- Move right to position 6 and harvest 2 fruits
-- Move right to position 7 and harvest 4 fruits
-You moved 1 + 3 = 4 steps and harvested 7 + 1 + 2 + 4 = 14 fruits in total.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/21/3.png" style="width: 476px; height: 100px;" />
-<pre>
-<strong>Input:</strong> fruits = [[0,3],[6,4],[8,5]], startPos = 3, k = 2
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-You can move at most k = 2 steps and cannot reach any position with fruits.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= fruits.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>fruits[i].length == 2</code></li>
-	<li><code>0 &lt;= startPos, position<sub>i</sub> &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>position<sub>i-1</sub> &lt; position<sub>i</sub></code> for any <code>i &gt; 0</code>&nbsp;(<strong>0-indexed</strong>)</li>
-	<li><code>1 &lt;= amount<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= k &lt;= 2 * 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Does an optimal path have very few patterns? For example, could a path that goes left, turns and goes right, then turns again and goes left be any better than a path that simply goes left, turns, and goes right?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The optimal path turns at most once. That is, the optimal path is one of these: to go left only; to go right only; to go left, turn and go right; or to go right, turn and go left.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Moving x steps left then k-x steps right gives you a range of positions that you can reach.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use prefix sums to get the sum of all fruits for each possible range.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Use a similar strategy for all the paths that go right, then turn and go left.
-</details>
diff --git a/problems/maximum-gap/README.md b/problems/maximum-gap/README.md
deleted file mode 100644
index d0c7d9316..000000000
--- a/problems/maximum-gap/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../missing-ranges "Missing Ranges")
-　　　　　　　　　　　　　　　　
-[Next >](../compare-version-numbers "Compare Version Numbers")
-
-## [164. Maximum Gap (Hard)](https://leetcode.com/problems/maximum-gap "最大间距")
-
-<p>Given an integer array <code>nums</code>, return <em>the maximum difference between two successive elements in its sorted form</em>. If the array contains less than two elements, return <code>0</code>.</p>
-
-<p>You must write an algorithm that runs in linear time and uses linear extra space.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,6,9,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The sorted form of the array is [1,3,6,9], either (3,6) or (6,9) has the maximum difference 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The array contains less than 2 elements, therefore return 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bucket Sort](../../tag/bucket-sort/README.md)]
-  [[Radix Sort](../../tag/radix-sort/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/maximum-gap/maximum_gap.go b/problems/maximum-gap/maximum_gap.go
deleted file mode 100644
index a5d338b69..000000000
--- a/problems/maximum-gap/maximum_gap.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem164
diff --git a/problems/maximum-gap/maximum_gap_test.go b/problems/maximum-gap/maximum_gap_test.go
deleted file mode 100644
index a5d338b69..000000000
--- a/problems/maximum-gap/maximum_gap_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem164
diff --git a/problems/maximum-genetic-difference-query/README.md b/problems/maximum-genetic-difference-query/README.md
deleted file mode 100644
index 1b13b9038..000000000
--- a/problems/maximum-genetic-difference-query/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-points-with-cost "Maximum Number of Points with Cost")
-　　　　　　　　　　　　　　　　
-[Next >](../users-that-actively-request-confirmation-messages "Users That Actively Request Confirmation Messages")
-
-## [1938. Maximum Genetic Difference Query (Hard)](https://leetcode.com/problems/maximum-genetic-difference-query "查询最大基因差")
-
-<p>There is a rooted tree consisting of <code>n</code> nodes numbered <code>0</code> to <code>n - 1</code>. Each node&#39;s number denotes its <strong>unique genetic value</strong> (i.e. the genetic value of node <code>x</code> is <code>x</code>). The <strong>genetic difference</strong> between two genetic values is defined as the <strong>bitwise-</strong><strong>XOR</strong> of their values. You are given the integer array <code>parents</code>, where <code>parents[i]</code> is the parent for node <code>i</code>. If node <code>x</code> is the <strong>root</strong> of the tree, then <code>parents[x] == -1</code>.</p>
-
-<p>You are also given the array <code>queries</code> where <code>queries[i] = [node<sub>i</sub>, val<sub>i</sub>]</code>. For each query <code>i</code>, find the <strong>maximum genetic difference</strong> between <code>val<sub>i</sub></code> and <code>p<sub>i</sub></code>, where <code>p<sub>i</sub></code> is the genetic value of any node that is on the path between <code>node<sub>i</sub></code> and the root (including <code>node<sub>i</sub></code> and the root). More formally, you want to maximize <code>val<sub>i</sub> XOR p<sub>i</sub></code>.</p>
-
-<p>Return <em>an array </em><code>ans</code><em> where </em><code>ans[i]</code><em> is the answer to the </em><code>i<sup>th</sup></code><em> query</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/c1.png" style="width: 118px; height: 163px;" />
-<pre>
-<strong>Input:</strong> parents = [-1,0,1,1], queries = [[0,2],[3,2],[2,5]]
-<strong>Output:</strong> [2,3,7]
-<strong>Explanation: </strong>The queries are processed as follows:
-- [0,2]: The node with the maximum genetic difference is 0, with a difference of 2 XOR 0 = 2.
-- [3,2]: The node with the maximum genetic difference is 1, with a difference of 2 XOR 1 = 3.
-- [2,5]: The node with the maximum genetic difference is 2, with a difference of 5 XOR 2 = 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/c2.png" style="width: 256px; height: 221px;" />
-<pre>
-<strong>Input:</strong> parents = [3,7,-1,2,0,7,0,2], queries = [[4,6],[1,15],[0,5]]
-<strong>Output:</strong> [6,14,7]
-<strong>Explanation: </strong>The queries are processed as follows:
-- [4,6]: The node with the maximum genetic difference is 0, with a difference of 6 XOR 0 = 6.
-- [1,15]: The node with the maximum genetic difference is 1, with a difference of 15 XOR 1 = 14.
-- [0,5]: The node with the maximum genetic difference is 2, with a difference of 5 XOR 2 = 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= parents.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= parents[i] &lt;= parents.length - 1</code> for every node <code>i</code> that is <strong>not</strong> the root.</li>
-	<li><code>parents[root] == -1</code></li>
-	<li><code>1 &lt;= queries.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= node<sub>i</sub> &lt;= parents.length - 1</code></li>
-	<li><code>0 &lt;= val<sub>i</sub> &lt;= 2 * 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Similar Questions
-  1. [Maximum XOR With an Element From Array](../maximum-xor-with-an-element-from-array) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can we use a trie to store all the XOR values in the path from a node to the root?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we dynamically add the XOR values with a DFS search?
-</details>
diff --git a/problems/maximum-good-people-based-on-statements/README.md b/problems/maximum-good-people-based-on-statements/README.md
deleted file mode 100644
index 9b0cf9661..000000000
--- a/problems/maximum-good-people-based-on-statements/README.md
+++ /dev/null
@@ -1,114 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-all-lonely-numbers-in-the-array "Find All Lonely Numbers in the Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-lines-to-cover-points "Minimum Number of Lines to Cover Points")
-
-## [2151. Maximum Good People Based on Statements (Hard)](https://leetcode.com/problems/maximum-good-people-based-on-statements "基于陈述统计最多好人数")
-
-<p>There are two types of persons:</p>
-
-<ul>
-	<li>The <strong>good person</strong>: The person who always tells the truth.</li>
-	<li>The <strong>bad person</strong>: The person who might tell the truth and might lie.</li>
-</ul>
-
-<p>You are given a <strong>0-indexed</strong> 2D integer array <code>statements</code> of size <code>n x n</code> that represents the statements made by <code>n</code> people about each other. More specifically, <code>statements[i][j]</code> could be one of the following:</p>
-
-<ul>
-	<li><code>0</code> which represents a statement made by person <code>i</code> that person <code>j</code> is a <strong>bad</strong> person.</li>
-	<li><code>1</code> which represents a statement made by person <code>i</code> that person <code>j</code> is a <strong>good</strong> person.</li>
-	<li><code>2</code> represents that <strong>no statement</strong> is made by person <code>i</code> about person <code>j</code>.</li>
-</ul>
-
-<p>Additionally, no person ever makes a statement about themselves. Formally, we have that <code>statements[i][i] = 2</code> for all <code>0 &lt;= i &lt; n</code>.</p>
-
-<p>Return <em>the <strong>maximum</strong> number of people who can be <strong>good</strong> based on the statements made by the </em><code>n</code><em> people</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2022/01/15/logic1.jpg" style="width: 600px; height: 262px;" />
-<pre>
-<strong>Input:</strong> statements = [[2,1,2],[1,2,2],[2,0,2]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Each person makes a single statement.
-- Person 0 states that person 1 is good.
-- Person 1 states that person 0 is good.
-- Person 2 states that person 1 is bad.
-Let&#39;s take person 2 as the key.
-- Assuming that person 2 is a good person:
-    - Based on the statement made by person 2, person 1 is a bad person.
-    - Now we know for sure that person 1 is bad and person 2 is good.
-    - Based on the statement made by person 1, and since person 1 is bad, they could be:
-        - telling the truth. There will be a contradiction in this case and this assumption is invalid.
-        - lying. In this case, person 0 is also a bad person and lied in their statement.
-    - <strong>Following that person 2 is a good person, there will be only one good person in the group</strong>.
-- Assuming that person 2 is a bad person:
-    - Based on the statement made by person 2, and since person 2 is bad, they could be:
-        - telling the truth. Following this scenario, person 0 and 1 are both bad as explained before.
-            - <strong>Following that person 2 is bad but told the truth, there will be no good persons in the group</strong>.
-        - lying. In this case person 1 is a good person.
-            - Since person 1 is a good person, person 0 is also a good person.
-            - <strong>Following that person 2 is bad and lied, there will be two good persons in the group</strong>.
-We can see that at most 2 persons are good in the best case, so we return 2.
-Note that there is more than one way to arrive at this conclusion.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2022/01/15/logic2.jpg" style="width: 600px; height: 262px;" />
-<pre>
-<strong>Input:</strong> statements = [[2,0],[0,2]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Each person makes a single statement.
-- Person 0 states that person 1 is bad.
-- Person 1 states that person 0 is bad.
-Let&#39;s take person 0 as the key.
-- Assuming that person 0 is a good person:
-    - Based on the statement made by person 0, person 1 is a bad person and was lying.
-    - <strong>Following that person 0 is a good person, there will be only one good person in the group</strong>.
-- Assuming that person 0 is a bad person:
-    - Based on the statement made by person 0, and since person 0 is bad, they could be:
-        - telling the truth. Following this scenario, person 0 and 1 are both bad.
-            - <strong>Following that person 0 is bad but told the truth, there will be no good persons in the group</strong>.
-        - lying. In this case person 1 is a good person.
-            - <strong>Following that person 0 is bad and lied, there will be only one good person in the group</strong>.
-We can see that at most, one person is good in the best case, so we return 1.
-Note that there is more than one way to arrive at this conclusion.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == statements.length == statements[i].length</code></li>
-	<li><code>2 &lt;= n &lt;= 15</code></li>
-	<li><code>statements[i][j]</code> is either <code>0</code>, <code>1</code>, or <code>2</code>.</li>
-	<li><code>statements[i][i] == 2</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You should test every possible assignment of good and bad people, using a bitmask.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In each bitmask, if the person i is good, then his statements should be consistent with the bitmask in order for the assignment to be valid.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If the assignment is valid, count how many people are good and keep track of the maximum.
-</details>
diff --git a/problems/maximum-height-by-stacking-cuboids/README.md b/problems/maximum-height-by-stacking-cuboids/README.md
deleted file mode 100644
index 4c988381f..000000000
--- a/problems/maximum-height-by-stacking-cuboids/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stone-game-vii "Stone Game VII")
-　　　　　　　　　　　　　　　　
-[Next >](../count-ways-to-distribute-candies "Count Ways to Distribute Candies")
-
-## [1691. Maximum Height by Stacking Cuboids  (Hard)](https://leetcode.com/problems/maximum-height-by-stacking-cuboids "堆叠长方体的最大高度")
-
-<p>Given <code>n</code> <code>cuboids</code> where the dimensions of the <code>i<sup>th</sup></code> cuboid is <code>cuboids[i] = [width<sub>i</sub>, length<sub>i</sub>, height<sub>i</sub>]</code> (<strong>0-indexed</strong>). Choose a <strong>subset</strong> of <code>cuboids</code> and place them on each other.</p>
-
-<p>You can place cuboid <code>i</code> on cuboid <code>j</code> if <code>width<sub>i</sub> &lt;= width<sub>j</sub></code> and <code>length<sub>i</sub> &lt;= length<sub>j</sub></code> and <code>height<sub>i</sub> &lt;= height<sub>j</sub></code>. You can rearrange any cuboid&#39;s dimensions by rotating it to put it on another cuboid.</p>
-
-<p>Return <em>the <strong>maximum height</strong> of the stacked</em> <code>cuboids</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/10/21/image.jpg" style="width: 420px; height: 299px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> cuboids = [[50,45,20],[95,37,53],[45,23,12]]
-<strong>Output:</strong> 190
-<strong>Explanation:</strong>
-Cuboid 1 is placed on the bottom with the 53x37 side facing down with height 95.
-Cuboid 0 is placed next with the 45x20 side facing down with height 50.
-Cuboid 2 is placed next with the 23x12 side facing down with height 45.
-The total height is 95 + 50 + 45 = 190.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> cuboids = [[38,25,45],[76,35,3]]
-<strong>Output:</strong> 76
-<strong>Explanation:</strong>
-You can&#39;t place any of the cuboids on the other.
-We choose cuboid 1 and rotate it so that the 35x3 side is facing down and its height is 76.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> cuboids = [[7,11,17],[7,17,11],[11,7,17],[11,17,7],[17,7,11],[17,11,7]]
-<strong>Output:</strong> 102
-<strong>Explanation:</strong>
-After rearranging the cuboids, you can see that all cuboids have the same dimension.
-You can place the 11x7 side down on all cuboids so their heights are 17.
-The maximum height of stacked cuboids is 6 * 17 = 102.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == cuboids.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= width<sub>i</sub>, length<sub>i</sub>, height<sub>i</sub> &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Does the dynamic programming sound like the right algorithm after sorting?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let's say box1 can be placed on top of box2. No matter what orientation box2 is in, we can rotate box1 so that it can be placed on top. Why don't we orient everything such that height is the biggest?
-</details>
diff --git a/problems/maximum-ice-cream-bars/README.md b/problems/maximum-ice-cream-bars/README.md
deleted file mode 100644
index 5b90aaafb..000000000
--- a/problems/maximum-ice-cream-bars/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-the-sentence-is-pangram "Check if the Sentence Is Pangram")
-　　　　　　　　　　　　　　　　
-[Next >](../single-threaded-cpu "Single-Threaded CPU")
-
-## [1833. Maximum Ice Cream Bars (Medium)](https://leetcode.com/problems/maximum-ice-cream-bars "雪糕的最大数量")
-
-<p>It is a sweltering summer day, and a boy wants to buy some ice cream bars.</p>
-
-<p>At the store, there are <code>n</code> ice cream bars. You are given an array <code>costs</code> of length <code>n</code>, where <code>costs[i]</code> is the price of the <code>i<sup>th</sup></code> ice cream bar in coins. The boy initially has <code>coins</code> coins to spend, and he wants to buy as many ice cream bars as possible.&nbsp;</p>
-
-<p>Return <em>the <strong>maximum</strong> number of ice cream bars the boy can buy with </em><code>coins</code><em> coins.</em></p>
-
-<p><strong>Note:</strong> The boy can buy the ice cream bars in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> costs = [1,3,2,4,1], coins = 7
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>The boy can buy ice cream bars at indices 0,1,2,4 for a total price of 1 + 3 + 2 + 1 = 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> costs = [10,6,8,7,7,8], coins = 5
-<strong>Output:</strong> 0
-<strong>Explanation: </strong>The boy cannot afford any of the ice cream bars.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> costs = [1,6,3,1,2,5], coins = 20
-<strong>Output:</strong> 6
-<strong>Explanation: </strong>The boy can buy all the ice cream bars for a total price of 1 + 6 + 3 + 1 + 2 + 5 = 18.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>costs.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= costs[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= coins &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-It is always optimal to buy the least expensive ice cream bar first.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort the prices so that the cheapest ice cream bar comes first.
-</details>
diff --git a/problems/maximum-length-of-a-concatenated-string-with-unique-characters/README.md b/problems/maximum-length-of-a-concatenated-string-with-unique-characters/README.md
deleted file mode 100644
index cc15cde53..000000000
--- a/problems/maximum-length-of-a-concatenated-string-with-unique-characters/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../circular-permutation-in-binary-representation "Circular Permutation in Binary Representation")
-　　　　　　　　　　　　　　　　
-[Next >](../tiling-a-rectangle-with-the-fewest-squares "Tiling a Rectangle with the Fewest Squares")
-
-## [1239. Maximum Length of a Concatenated String with Unique Characters (Medium)](https://leetcode.com/problems/maximum-length-of-a-concatenated-string-with-unique-characters "串联字符串的最大长度")
-
-<p>You are given an array of strings <code>arr</code>. A string <code>s</code> is formed by the <strong>concatenation</strong> of a <strong>subsequence</strong> of <code>arr</code> that has <strong>unique characters</strong>.</p>
-
-<p>Return <em>the <strong>maximum</strong> possible length</em> of <code>s</code>.</p>
-
-<p>A <strong>subsequence</strong> is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [&quot;un&quot;,&quot;iq&quot;,&quot;ue&quot;]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> All the valid concatenations are:
-- &quot;&quot;
-- &quot;un&quot;
-- &quot;iq&quot;
-- &quot;ue&quot;
-- &quot;uniq&quot; (&quot;un&quot; + &quot;iq&quot;)
-- &quot;ique&quot; (&quot;iq&quot; + &quot;ue&quot;)
-Maximum length is 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [&quot;cha&quot;,&quot;r&quot;,&quot;act&quot;,&quot;ers&quot;]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Possible longest valid concatenations are &quot;chaers&quot; (&quot;cha&quot; + &quot;ers&quot;) and &quot;acters&quot; (&quot;act&quot; + &quot;ers&quot;).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [&quot;abcdefghijklmnopqrstuvwxyz&quot;]
-<strong>Output:</strong> 26
-<strong>Explanation:</strong> The only string in arr has all 26 characters.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 16</code></li>
-	<li><code>1 &lt;= arr[i].length &lt;= 26</code></li>
-	<li><code>arr[i]</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can try all combinations and keep mask of characters you have.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can use DP.
-</details>
diff --git a/problems/maximum-length-of-pair-chain/README.md b/problems/maximum-length-of-pair-chain/README.md
deleted file mode 100644
index a7e566c55..000000000
--- a/problems/maximum-length-of-pair-chain/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../set-mismatch "Set Mismatch")
-　　　　　　　　　　　　　　　　
-[Next >](../palindromic-substrings "Palindromic Substrings")
-
-## [646. Maximum Length of Pair Chain (Medium)](https://leetcode.com/problems/maximum-length-of-pair-chain "最长数对链")
-
-<p>You are given an array of <code>n</code> pairs <code>pairs</code> where <code>pairs[i] = [left<sub>i</sub>, right<sub>i</sub>]</code> and <code>left<sub>i</sub> &lt; right<sub>i</sub></code>.</p>
-
-<p>A pair <code>p2 = [c, d]</code> <strong>follows</strong> a pair <code>p1 = [a, b]</code> if <code>b &lt; c</code>. A <strong>chain</strong> of pairs can be formed in this fashion.</p>
-
-<p>Return <em>the length longest chain which can be formed</em>.</p>
-
-<p>You do not need to use up all the given intervals. You can select pairs in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> pairs = [[1,2],[2,3],[3,4]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The longest chain is [1,2] -&gt; [3,4].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> pairs = [[1,2],[7,8],[4,5]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The longest chain is [1,2] -&gt; [4,5] -&gt; [7,8].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == pairs.length</code></li>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>-1000 &lt;= left<sub>i</sub> &lt; right<sub>i</sub> &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Longest Increasing Subsequence](../longest-increasing-subsequence) (Medium)
-  1. [Increasing Subsequences](../increasing-subsequences) (Medium)
diff --git a/problems/maximum-length-of-pair-chain/maximum_length_of_pair_chain.go b/problems/maximum-length-of-pair-chain/maximum_length_of_pair_chain.go
deleted file mode 100644
index 885d2506c..000000000
--- a/problems/maximum-length-of-pair-chain/maximum_length_of_pair_chain.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem646
diff --git a/problems/maximum-length-of-pair-chain/maximum_length_of_pair_chain_test.go b/problems/maximum-length-of-pair-chain/maximum_length_of_pair_chain_test.go
deleted file mode 100644
index 885d2506c..000000000
--- a/problems/maximum-length-of-pair-chain/maximum_length_of_pair_chain_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem646
diff --git a/problems/maximum-length-of-repeated-subarray/README.md b/problems/maximum-length-of-repeated-subarray/README.md
deleted file mode 100644
index 1ac8a6857..000000000
--- a/problems/maximum-length-of-repeated-subarray/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../1-bit-and-2-bit-characters "1-bit and 2-bit Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../find-k-th-smallest-pair-distance "Find K-th Smallest Pair Distance")
-
-## [718. Maximum Length of Repeated Subarray (Medium)](https://leetcode.com/problems/maximum-length-of-repeated-subarray "最长重复子数组")
-
-<p>Given two integer arrays <code>nums1</code> and <code>nums2</code>, return <em>the maximum length of a subarray that appears in <strong>both</strong> arrays</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2,3,2,1], nums2 = [3,2,1,4,7]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The repeated subarray with maximum length is [3,2,1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [0,0,0,0,0], nums2 = [0,0,0,0,0]
-<strong>Output:</strong> 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums1[i], nums2[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Similar Questions
-  1. [Minimum Size Subarray Sum](../minimum-size-subarray-sum) (Medium)
-  1. [Longest Common Subpath](../longest-common-subpath) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.  dp[i][j] will be the answer for inputs A[i:], B[j:].
-</details>
diff --git a/problems/maximum-length-of-repeated-subarray/maximum_length_of_repeated_subarray.go b/problems/maximum-length-of-repeated-subarray/maximum_length_of_repeated_subarray.go
deleted file mode 100644
index 41a41d01f..000000000
--- a/problems/maximum-length-of-repeated-subarray/maximum_length_of_repeated_subarray.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem718
diff --git a/problems/maximum-length-of-repeated-subarray/maximum_length_of_repeated_subarray_test.go b/problems/maximum-length-of-repeated-subarray/maximum_length_of_repeated_subarray_test.go
deleted file mode 100644
index 41a41d01f..000000000
--- a/problems/maximum-length-of-repeated-subarray/maximum_length_of_repeated_subarray_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem718
diff --git a/problems/maximum-length-of-subarray-with-positive-product/README.md b/problems/maximum-length-of-subarray-with-positive-product/README.md
deleted file mode 100644
index d1b1c444c..000000000
--- a/problems/maximum-length-of-subarray-with-positive-product/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../detect-pattern-of-length-m-repeated-k-or-more-times "Detect Pattern of Length M Repeated K or More Times")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-days-to-disconnect-island "Minimum Number of Days to Disconnect Island")
-
-## [1567. Maximum Length of Subarray With Positive Product (Medium)](https://leetcode.com/problems/maximum-length-of-subarray-with-positive-product "乘积为正数的最长子数组长度")
-
-<p>Given an array of integers <code>nums</code>, find the maximum length of a subarray where the product of all its elements is positive.</p>
-
-<p>A subarray of an array is a consecutive sequence of zero or more values taken out of that array.</p>
-
-<p>Return <em>the maximum length of a subarray with positive product</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,-2,-3,4]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The array nums already has a positive product of 24.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,-2,-3,-4]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The longest subarray with positive product is [1,-2,-3] which has a product of 6.
-Notice that we cannot include 0 in the subarray since that&#39;ll make the product 0 which is not positive.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,-2,-3,0,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The longest subarray with positive product is [-1,-2] or [-2,-3].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Split the whole array into subarrays by zeroes since a subarray with positive product cannot contain any zero.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the subarray has even number of negative numbers, the whole subarray has positive product.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Otherwise, we have two choices, either - remove the prefix till the first negative element in this subarray, or remove the suffix starting from the last negative element in this subarray.
-</details>
diff --git a/problems/maximum-level-sum-of-a-binary-tree/README.md b/problems/maximum-level-sum-of-a-binary-tree/README.md
deleted file mode 100644
index f91184c27..000000000
--- a/problems/maximum-level-sum-of-a-binary-tree/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-words-that-can-be-formed-by-characters "Find Words That Can Be Formed by Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../as-far-from-land-as-possible "As Far from Land as Possible")
-
-## [1161. Maximum Level Sum of a Binary Tree (Medium)](https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree "最大层内元素和")
-
-<p>Given the <code>root</code> of a binary tree, the level of its root is <code>1</code>, the level of its children is <code>2</code>, and so on.</p>
-
-<p>Return the <strong>smallest</strong> level <code>x</code> such that the sum of all the values of nodes at level <code>x</code> is <strong>maximal</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/05/03/capture.JPG" style="width: 200px; height: 175px;" />
-<pre>
-<strong>Input:</strong> root = [1,7,0,7,-8,null,null]
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>
-Level 1 sum = 1.
-Level 2 sum = 7 + 0 = 7.
-Level 3 sum = 7 + -8 = -1.
-So we return the level with the maximum sum which is level 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [989,null,10250,98693,-89388,null,null,null,-32127]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Calculate the sum for each level then find the level with the maximum sum.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can you traverse the tree ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How can you sum up the values for every level ?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use DFS or BFS to traverse the tree keeping the level of each node, and sum up those values with a map or a frequency array.
-</details>
diff --git a/problems/maximum-matrix-sum/README.md b/problems/maximum-matrix-sum/README.md
deleted file mode 100644
index 8eb766ade..000000000
--- a/problems/maximum-matrix-sum/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-time-to-type-word-using-special-typewriter "Minimum Time to Type Word Using Special Typewriter")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-arrive-at-destination "Number of Ways to Arrive at Destination")
-
-## [1975. Maximum Matrix Sum (Medium)](https://leetcode.com/problems/maximum-matrix-sum "最大方阵和")
-
-<p>You are given an <code>n x n</code> integer <code>matrix</code>. You can do the following operation <strong>any</strong> number of times:</p>
-
-<ul>
-	<li>Choose any two <strong>adjacent</strong> elements of <code>matrix</code> and <strong>multiply</strong> each of them by <code>-1</code>.</li>
-</ul>
-
-<p>Two elements are considered <strong>adjacent</strong> if and only if they share a <strong>border</strong>.</p>
-
-<p>Your goal is to <strong>maximize</strong> the summation of the matrix&#39;s elements. Return <em>the <strong>maximum</strong> sum of the matrix&#39;s elements using the operation mentioned above.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/16/pc79-q2ex1.png" style="width: 401px; height: 81px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,-1],[-1,1]]
-<strong>Output:</strong> 4
-<b>Explanation:</b> We can follow the following steps to reach sum equals 4:
-- Multiply the 2 elements in the first row by -1.
-- Multiply the 2 elements in the first column by -1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/16/pc79-q2ex2.png" style="width: 321px; height: 121px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,2,3],[-1,-2,-3],[1,2,3]]
-<strong>Output:</strong> 16
-<b>Explanation:</b> We can follow the following step to reach sum equals 16:
-- Multiply the 2 last elements in the second row by -1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == matrix.length == matrix[i].length</code></li>
-	<li><code>2 &lt;= n &lt;= 250</code></li>
-	<li><code>-10<sup>5</sup> &lt;= matrix[i][j] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to use the operation so that each row has only one negative number.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you have only one negative element you cannot convert it to positive.
-</details>
diff --git a/problems/maximum-nesting-depth-of-the-parentheses/README.md b/problems/maximum-nesting-depth-of-the-parentheses/README.md
deleted file mode 100644
index 93c9ebc78..000000000
--- a/problems/maximum-nesting-depth-of-the-parentheses/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-missing-ids "Find the Missing IDs")
-　　　　　　　　　　　　　　　　
-[Next >](../maximal-network-rank "Maximal Network Rank")
-
-## [1614. Maximum Nesting Depth of the Parentheses (Easy)](https://leetcode.com/problems/maximum-nesting-depth-of-the-parentheses "括号的最大嵌套深度")
-
-<p>A string is a <strong>valid parentheses string</strong> (denoted <strong>VPS</strong>) if it meets one of the following:</p>
-
-<ul>
-	<li>It is an empty string <code>&quot;&quot;</code>, or a single character not equal to <code>&quot;(&quot;</code> or <code>&quot;)&quot;</code>,</li>
-	<li>It can be written as <code>AB</code> (<code>A</code> concatenated with <code>B</code>), where <code>A</code> and <code>B</code> are <strong>VPS</strong>&#39;s, or</li>
-	<li>It can be written as <code>(A)</code>, where <code>A</code> is a <strong>VPS</strong>.</li>
-</ul>
-
-<p>We can similarly define the <strong>nesting depth</strong> <code>depth(S)</code> of any VPS <code>S</code> as follows:</p>
-
-<ul>
-	<li><code>depth(&quot;&quot;) = 0</code></li>
-	<li><code>depth(C) = 0</code>, where <code>C</code> is a string with a single character not equal to <code>&quot;(&quot;</code> or <code>&quot;)&quot;</code>.</li>
-	<li><code>depth(A + B) = max(depth(A), depth(B))</code>, where <code>A</code> and <code>B</code> are <strong>VPS</strong>&#39;s.</li>
-	<li><code>depth(&quot;(&quot; + A + &quot;)&quot;) = 1 + depth(A)</code>, where <code>A</code> is a <strong>VPS</strong>.</li>
-</ul>
-
-<p>For example, <code>&quot;&quot;</code>, <code>&quot;()()&quot;</code>, and <code>&quot;()(()())&quot;</code> are <strong>VPS</strong>&#39;s (with nesting depths 0, 1, and 2), and <code>&quot;)(&quot;</code> and <code>&quot;(()&quot;</code> are not <strong>VPS</strong>&#39;s.</p>
-
-<p>Given a <strong>VPS</strong> represented as string <code>s</code>, return <em>the <strong>nesting depth</strong> of </em><code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(1+(2*3)+((<u>8</u>)/4))+1&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Digit 8 is inside of 3 nested parentheses in the string.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(1)+((2))+(((<u>3</u>)))&quot;
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> consists of digits <code>0-9</code> and characters <code>&#39;+&#39;</code>, <code>&#39;-&#39;</code>, <code>&#39;*&#39;</code>, <code>&#39;/&#39;</code>, <code>&#39;(&#39;</code>, and <code>&#39;)&#39;</code>.</li>
-	<li>It is guaranteed that parentheses expression <code>s</code> is a <strong>VPS</strong>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-
-### Similar Questions
-  1. [Maximum Nesting Depth of Two Valid Parentheses Strings](../maximum-nesting-depth-of-two-valid-parentheses-strings) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The depth of any character in the VPS is the ( number of left brackets before it ) - ( number of right brackets before it )
-</details>
diff --git a/problems/maximum-nesting-depth-of-two-valid-parentheses-strings/README.md b/problems/maximum-nesting-depth-of-two-valid-parentheses-strings/README.md
deleted file mode 100644
index ef9ae45b3..000000000
--- a/problems/maximum-nesting-depth-of-two-valid-parentheses-strings/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-nodes-and-return-forest "Delete Nodes And Return Forest")
-　　　　　　　　　　　　　　　　
-[Next >](../highest-grade-for-each-student "Highest Grade For Each Student")
-
-## [1111. Maximum Nesting Depth of Two Valid Parentheses Strings (Medium)](https://leetcode.com/problems/maximum-nesting-depth-of-two-valid-parentheses-strings "有效括号的嵌套深度")
-
-<p>A string is a <em>valid parentheses string</em>&nbsp;(denoted VPS) if and only if it consists of <code>&quot;(&quot;</code> and <code>&quot;)&quot;</code> characters only, and:</p>
-
-<ul>
-	<li>It is the empty string, or</li>
-	<li>It can be written as&nbsp;<code>AB</code>&nbsp;(<code>A</code>&nbsp;concatenated with&nbsp;<code>B</code>), where&nbsp;<code>A</code>&nbsp;and&nbsp;<code>B</code>&nbsp;are VPS&#39;s, or</li>
-	<li>It can be written as&nbsp;<code>(A)</code>, where&nbsp;<code>A</code>&nbsp;is a VPS.</li>
-</ul>
-
-<p>We can&nbsp;similarly define the <em>nesting depth</em> <code>depth(S)</code> of any VPS <code>S</code> as follows:</p>
-
-<ul>
-	<li><code>depth(&quot;&quot;) = 0</code></li>
-	<li><code>depth(A + B) = max(depth(A), depth(B))</code>, where <code>A</code> and <code>B</code> are VPS&#39;s</li>
-	<li><code>depth(&quot;(&quot; + A + &quot;)&quot;) = 1 + depth(A)</code>, where <code>A</code> is a VPS.</li>
-</ul>
-
-<p>For example,&nbsp; <code>&quot;&quot;</code>,&nbsp;<code>&quot;()()&quot;</code>, and&nbsp;<code>&quot;()(()())&quot;</code>&nbsp;are VPS&#39;s (with nesting depths 0, 1, and 2), and <code>&quot;)(&quot;</code> and <code>&quot;(()&quot;</code> are not VPS&#39;s.</p>
-
-<p>&nbsp;</p>
-
-<p>Given a VPS <font face="monospace">seq</font>, split it into two disjoint subsequences <code>A</code> and <code>B</code>, such that&nbsp;<code>A</code> and <code>B</code> are VPS&#39;s (and&nbsp;<code>A.length + B.length = seq.length</code>).</p>
-
-<p>Now choose <strong>any</strong> such <code>A</code> and <code>B</code> such that&nbsp;<code>max(depth(A), depth(B))</code> is the minimum possible value.</p>
-
-<p>Return an <code>answer</code> array (of length <code>seq.length</code>) that encodes such a&nbsp;choice of <code>A</code> and <code>B</code>:&nbsp; <code>answer[i] = 0</code> if <code>seq[i]</code> is part of <code>A</code>, else <code>answer[i] = 1</code>.&nbsp; Note that even though multiple answers may exist, you may return any of them.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> seq = &quot;(()())&quot;
-<strong>Output:</strong> [0,1,1,1,1,0]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> seq = &quot;()(())()&quot;
-<strong>Output:</strong> [0,0,0,1,1,0,1,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= seq.size &lt;= 10000</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-
-### Similar Questions
-  1. [Maximum Nesting Depth of the Parentheses](../maximum-nesting-depth-of-the-parentheses) (Easy)
diff --git a/problems/maximum-nesting-depth-of-two-valid-parentheses-strings/maximum_nesting_depth_of_two_valid_parentheses_strings.go b/problems/maximum-nesting-depth-of-two-valid-parentheses-strings/maximum_nesting_depth_of_two_valid_parentheses_strings.go
deleted file mode 100644
index fe042a468..000000000
--- a/problems/maximum-nesting-depth-of-two-valid-parentheses-strings/maximum_nesting_depth_of_two_valid_parentheses_strings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1111
diff --git a/problems/maximum-non-negative-product-in-a-matrix/README.md b/problems/maximum-non-negative-product-in-a-matrix/README.md
deleted file mode 100644
index 061a705d5..000000000
--- a/problems/maximum-non-negative-product-in-a-matrix/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-a-string-into-the-max-number-of-unique-substrings "Split a String Into the Max Number of Unique Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-connect-two-groups-of-points "Minimum Cost to Connect Two Groups of Points")
-
-## [1594. Maximum Non Negative Product in a Matrix (Medium)](https://leetcode.com/problems/maximum-non-negative-product-in-a-matrix "矩阵的最大非负积")
-
-<p>You are given a <code>m x n</code> matrix <code>grid</code>. Initially, you are located at the top-left corner <code>(0, 0)</code>, and in each step, you can only <strong>move right or down</strong> in the matrix.</p>
-
-<p>Among all possible paths starting from the top-left corner <code>(0, 0)</code> and ending in the bottom-right corner <code>(m - 1, n - 1)</code>, find the path with the <strong>maximum non-negative product</strong>. The product of a path is the product of all integers in the grid cells visited along the path.</p>
-
-<p>Return the <em>maximum non-negative product <strong>modulo</strong> </em><code>10<sup>9</sup> + 7</code>. <em>If the maximum product is <strong>negative</strong>, return </em><code>-1</code>.</p>
-
-<p>Notice that the modulo is performed after getting the maximum product.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/23/product1.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> grid = [[-1,-2,-3],[-2,-3,-3],[-3,-3,-2]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> It is not possible to get non-negative product in the path from (0, 0) to (2, 2), so return -1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/23/product2.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,-2,1],[1,-2,1],[3,-4,1]]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> Maximum non-negative product is shown (1 * 1 * -2 * -4 * 1 = 8).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/23/product3.jpg" style="width: 164px; height: 165px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,3],[0,-4]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Maximum non-negative product is shown (1 * 0 * -4 = 0).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 15</code></li>
-	<li><code>-4 &lt;= grid[i][j] &lt;= 4</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use Dynamic programming. Keep the highest value and lowest value you can achieve up to a point.
-</details>
diff --git a/problems/maximum-number-of-accepted-invitations/README.md b/problems/maximum-number-of-accepted-invitations/README.md
deleted file mode 100644
index ef403fdb6..000000000
--- a/problems/maximum-number-of-accepted-invitations/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-different-subsequences-gcds "Number of Different Subsequences GCDs")
-　　　　　　　　　　　　　　　　
-[Next >](../find-customers-with-positive-revenue-this-year "Find Customers With Positive Revenue this Year")
-
-## [1820. Maximum Number of Accepted Invitations (Medium)](https://leetcode.com/problems/maximum-number-of-accepted-invitations "最多邀请的个数")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can see that the problem can be represented as a directed graph with an edge from each boy to the girl he invited.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We need to choose a set of edges such that no to source points in the graph (i.e., boys) have an edge with the same endpoint (i.e., the same girl).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The problem is maximum bipartite matching in the graph.
-</details>
diff --git a/problems/maximum-number-of-achievable-transfer-requests/README.md b/problems/maximum-number-of-achievable-transfer-requests/README.md
deleted file mode 100644
index 8c9be33c7..000000000
--- a/problems/maximum-number-of-achievable-transfer-requests/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../throne-inheritance "Throne Inheritance")
-　　　　　　　　　　　　　　　　
-[Next >](../find-nearest-right-node-in-binary-tree "Find Nearest Right Node in Binary Tree")
-
-## [1601. Maximum Number of Achievable Transfer Requests (Hard)](https://leetcode.com/problems/maximum-number-of-achievable-transfer-requests "最多可达成的换楼请求数目")
-
-<p>We have <code>n</code> buildings numbered from <code>0</code> to <code>n - 1</code>. Each building has a number of employees. It&#39;s transfer season, and some employees want to change the building they reside in.</p>
-
-<p>You are given an array <code>requests</code> where <code>requests[i] = [from<sub>i</sub>, to<sub>i</sub>]</code> represents an employee&#39;s request to transfer from building <code>from<sub>i</sub></code> to building <code>to<sub>i</sub></code>.</p>
-
-<p><strong>All buildings are full</strong>, so a list of requests is achievable only if for each building, the <strong>net change in employee transfers is zero</strong>. This means the number of employees <strong>leaving</strong> is <strong>equal</strong> to the number of employees <strong>moving in</strong>. For example if <code>n = 3</code> and two employees are leaving building <code>0</code>, one is leaving building <code>1</code>, and one is leaving building <code>2</code>, there should be two employees moving to building <code>0</code>, one employee moving to building <code>1</code>, and one employee moving to building <code>2</code>.</p>
-
-<p>Return <em>the maximum number of achievable requests</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/10/move1.jpg" style="width: 600px; height: 406px;" />
-<pre>
-<strong>Input:</strong> n = 5, requests = [[0,1],[1,0],[0,1],[1,2],[2,0],[3,4]]
-<strong>Output:</strong> 5
-<strong>Explantion:</strong> Let&#39;s see the requests:
-From building 0 we have employees x and y and both want to move to building 1.
-From building 1 we have employees a and b and they want to move to buildings 2 and 0 respectively.
-From building 2 we have employee z and they want to move to building 0.
-From building 3 we have employee c and they want to move to building 4.
-From building 4 we don&#39;t have any requests.
-We can achieve the requests of users x and b by swapping their places.
-We can achieve the requests of users y, a and z by swapping the places in the 3 buildings.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/10/move2.jpg" style="width: 450px; height: 327px;" />
-<pre>
-<strong>Input:</strong> n = 3, requests = [[0,0],[1,2],[2,1]]
-<strong>Output:</strong> 3
-<strong>Explantion:</strong> Let&#39;s see the requests:
-From building 0 we have employee x and they want to stay in the same building 0.
-From building 1 we have employee y and they want to move to building 2.
-From building 2 we have employee z and they want to move to building 1.
-We can achieve all the requests. </pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, requests = [[0,3],[3,1],[1,2],[2,0]]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-	<li><code>1 &lt;= requests.length &lt;= 16</code></li>
-	<li><code>requests[i].length == 2</code></li>
-	<li><code>0 &lt;= from<sub>i</sub>, to<sub>i</sub> &lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think brute force
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When is a subset of requests okay?
-</details>
diff --git a/problems/maximum-number-of-balloons/README.md b/problems/maximum-number-of-balloons/README.md
deleted file mode 100644
index b871476da..000000000
--- a/problems/maximum-number-of-balloons/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-bounded-blocking-queue "Design Bounded Blocking Queue")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-substrings-between-each-pair-of-parentheses "Reverse Substrings Between Each Pair of Parentheses")
-
-## [1189. Maximum Number of Balloons (Easy)](https://leetcode.com/problems/maximum-number-of-balloons "“气球” 的最大数量")
-
-<p>Given a string <code>text</code>, you want to use the characters of <code>text</code> to form as many instances of the word <strong>&quot;balloon&quot;</strong> as possible.</p>
-
-<p>You can use each character in <code>text</code> <strong>at most once</strong>. Return the maximum number of instances that can be formed.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/09/05/1536_ex1_upd.JPG" style="width: 132px; height: 35px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;nlaebolko&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/09/05/1536_ex2_upd.JPG" style="width: 267px; height: 35px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;loonbalxballpoon&quot;
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;leetcode&quot;
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= text.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>text</code> consists of lower case English letters only.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the frequency of letters in the given string.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the letter than can make the minimum number of instances of the word "balloon".
-</details>
diff --git a/problems/maximum-number-of-balloons/maximum_number_of_balloons.go b/problems/maximum-number-of-balloons/maximum_number_of_balloons.go
deleted file mode 100644
index 264646152..000000000
--- a/problems/maximum-number-of-balloons/maximum_number_of_balloons.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem1189
-
-func maxNumberOfBalloons(text string) int {
-	ans, m := len(text), make(map[byte]int, 5)
-	for i := 0; i < ans; i++ {
-		switch text[i] {
-		case 'b', 'a', 'l', 'o', 'n':
-			m[text[i]]++
-		}
-	}
-	for _, c := range [...]byte{'b', 'a', 'l', 'o', 'n'} {
-		if c == 'l' || c == 'o' {
-			m[c] /= 2
-		}
-		if ans > m[c] {
-			ans = m[c]
-		}
-	}
-	return ans
-}
diff --git a/problems/maximum-number-of-balloons/maximum_number_of_balloons_test.go b/problems/maximum-number-of-balloons/maximum_number_of_balloons_test.go
deleted file mode 100644
index 14206e51b..000000000
--- a/problems/maximum-number-of-balloons/maximum_number_of_balloons_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1189
-
-import "testing"
-
-type testType struct {
-	in   string
-	want int
-}
-
-func TestMaxNumberOfBalloons(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "nlaebolko",
-			want: 1,
-		},
-		{
-			in:   "loonbalxballpoon",
-			want: 2,
-		},
-		{
-			in:   "leetcode",
-			want: 0,
-		},
-		{
-			in:   "lloo",
-			want: 0,
-		},
-	}
-	for _, tt := range tests {
-		got := maxNumberOfBalloons(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/maximum-number-of-balls-in-a-box/README.md b/problems/maximum-number-of-balls-in-a-box/README.md
deleted file mode 100644
index a31e84d04..000000000
--- a/problems/maximum-number-of-balls-in-a-box/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-total-time-spent-by-each-employee "Find Total Time Spent by Each Employee")
-　　　　　　　　　　　　　　　　
-[Next >](../restore-the-array-from-adjacent-pairs "Restore the Array From Adjacent Pairs")
-
-## [1742. Maximum Number of Balls in a Box (Easy)](https://leetcode.com/problems/maximum-number-of-balls-in-a-box "盒子中小球的最大数量")
-
-<p>You are working in a ball factory where you have <code>n</code> balls numbered from <code>lowLimit</code> up to <code>highLimit</code> <strong>inclusive</strong> (i.e., <code>n == highLimit - lowLimit + 1</code>), and an infinite number of boxes numbered from <code>1</code> to <code>infinity</code>.</p>
-
-<p>Your job at this factory is to put each ball in the box with a number equal to the sum of digits of the ball&#39;s number. For example, the ball number <code>321</code> will be put in the box number <code>3 + 2 + 1 = 6</code> and the ball number <code>10</code> will be put in the box number <code>1 + 0 = 1</code>.</p>
-
-<p>Given two integers <code>lowLimit</code> and <code>highLimit</code>, return<em> the number of balls in the box with the most balls.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> lowLimit = 1, highLimit = 10
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-Box Number:  1 2 3 4 5 6 7 8 9 10 11 ...
-Ball Count:  2 1 1 1 1 1 1 1 1 0  0  ...
-Box 1 has the most number of balls with 2 balls.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> lowLimit = 5, highLimit = 15
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-Box Number:  1 2 3 4 5 6 7 8 9 10 11 ...
-Ball Count:  1 1 1 1 2 2 1 1 1 0  0  ...
-Boxes 5 and 6 have the most number of balls with 2 balls in each.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> lowLimit = 19, highLimit = 28
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-Box Number:  1 2 3 4 5 6 7 8 9 10 11 12 ...
-Ball Count:  0 1 1 1 1 1 1 1 1 2  0  0  ...
-Box 10 has the most number of balls with 2 balls.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= lowLimit &lt;= highLimit &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that both lowLimit and highLimit are of small constraints so you can iterate on all nubmer between them
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can simulate the boxes by counting for each box the number of balls with digit sum equal to that box number
-</details>
diff --git a/problems/maximum-number-of-coins-you-can-get/README.md b/problems/maximum-number-of-coins-you-can-get/README.md
deleted file mode 100644
index 61ecb3167..000000000
--- a/problems/maximum-number-of-coins-you-can-get/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../most-visited-sector-in-a-circular-track "Most Visited Sector in  a Circular Track")
-　　　　　　　　　　　　　　　　
-[Next >](../find-latest-group-of-size-m "Find Latest Group of Size M")
-
-## [1561. Maximum Number of Coins You Can Get (Medium)](https://leetcode.com/problems/maximum-number-of-coins-you-can-get "你可以获得的最大硬币数目")
-
-<p>There are <code>3n</code> piles of coins of varying size, you and your friends will take piles of coins as follows:</p>
-
-<ul>
-	<li>In each step, you will choose <strong>any </strong><code>3</code> piles of coins (not necessarily consecutive).</li>
-	<li>Of your choice, Alice will pick the pile with the maximum number of coins.</li>
-	<li>You will pick the next pile with the maximum number of coins.</li>
-	<li>Your friend Bob will pick the last pile.</li>
-	<li>Repeat until there are no more piles of coins.</li>
-</ul>
-
-<p>Given an array of integers <code>piles</code> where <code>piles[i]</code> is the number of coins in the <code>i<sup>th</sup></code> pile.</p>
-
-<p>Return the maximum number of coins that you can have.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [2,4,1,2,7,8]
-<strong>Output:</strong> 9
-<strong>Explanation: </strong>Choose the triplet (2, 7, 8), Alice Pick the pile with 8 coins, you the pile with <strong>7</strong> coins and Bob the last one.
-Choose the triplet (1, 2, 4), Alice Pick the pile with 4 coins, you the pile with <strong>2</strong> coins and Bob the last one.
-The maximum number of coins which you can have are: 7 + 2 = 9.
-On the other hand if we choose this arrangement (1, <strong>2</strong>, 8), (2, <strong>4</strong>, 7) you only get 2 + 4 = 6 coins which is not optimal.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [2,4,5]
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [9,8,7,6,5,1,2,3,4]
-<strong>Output:</strong> 18
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= piles.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>piles.length % 3 == 0</code></li>
-	<li><code>1 &lt;= piles[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Which pile of coins will you never be able to pick up?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Bob is forced to take the last pile of coins, no matter what it is. Which pile should you give to him?
-</details>
diff --git a/problems/maximum-number-of-consecutive-values-you-can-make/README.md b/problems/maximum-number-of-consecutive-values-you-can-make/README.md
deleted file mode 100644
index b0826514c..000000000
--- a/problems/maximum-number-of-consecutive-values-you-can-make/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-authentication-manager "Design Authentication Manager")
-　　　　　　　　　　　　　　　　
-[Next >](../maximize-score-after-n-operations "Maximize Score After N Operations")
-
-## [1798. Maximum Number of Consecutive Values You Can Make (Medium)](https://leetcode.com/problems/maximum-number-of-consecutive-values-you-can-make "你能构造出连续值的最大数目")
-
-<p>You are given an integer array <code>coins</code> of length <code>n</code> which represents the <code>n</code> coins that you own. The value of the <code>i<sup>th</sup></code> coin is <code>coins[i]</code>. You can <strong>make</strong> some value <code>x</code> if you can choose some of your <code>n</code> coins such that their values sum up to <code>x</code>.</p>
-
-<p>Return the <em>maximum number of consecutive integer values that you <strong>can</strong> <strong>make</strong> with your coins <strong>starting</strong> from and <strong>including</strong> </em><code>0</code>.</p>
-
-<p>Note that you may have multiple coins of the same value.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> coins = [1,3]
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>You can make the following values:
-- 0: take []
-- 1: take [1]
-You can make 2 consecutive integer values starting from 0.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> coins = [1,1,1,4]
-<strong>Output:</strong> 8
-<strong>Explanation: </strong>You can make the following values:
-- 0: take []
-- 1: take [1]
-- 2: take [1,1]
-- 3: take [1,1,1]
-- 4: take [4]
-- 5: take [4,1]
-- 6: take [4,1,1]
-- 7: take [4,1,1,1]
-You can make 8 consecutive integer values starting from 0.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,4,10,3,1]
-<strong>Output:</strong> 20</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>coins.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 4 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= coins[i] &lt;= 4 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Patching Array](../patching-array) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you can make the first x values and you have a value v, then you can make all the values <var>≤ v + x</var>
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort the array of coins. You can always make the value 0 so you can start with x = 0.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Process the values starting from the smallest and stop when there is a value that cannot be achieved with the current x.
-</details>
diff --git a/problems/maximum-number-of-darts-inside-of-a-circular-dartboard/README.md b/problems/maximum-number-of-darts-inside-of-a-circular-dartboard/README.md
deleted file mode 100644
index 7767a3d0e..000000000
--- a/problems/maximum-number-of-darts-inside-of-a-circular-dartboard/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list "People Whose List of Favorite Companies Is Not a Subset of Another List")
-　　　　　　　　　　　　　　　　
-[Next >](../active-users "Active Users")
-
-## [1453. Maximum Number of Darts Inside of a Circular Dartboard (Hard)](https://leetcode.com/problems/maximum-number-of-darts-inside-of-a-circular-dartboard "圆形靶内的最大飞镖数量")
-
-<p>Alice is throwing <code>n</code> darts on a very large wall. You are given an array <code>darts</code> where <code>darts[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> is the position of the <code>i<sup>th</sup></code> dart that Alice threw on the wall.</p>
-
-<p>Bob knows the positions of the <code>n</code> darts on the wall. He wants to place a dartboard of radius <code>r</code> on the wall so that the maximum number of darts that Alice throws lies on the dartboard.</p>
-
-<p>Given the integer <code>r</code>, return <em>the maximum number of darts that can lie on the dartboard</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/04/29/sample_1_1806.png" style="width: 248px; height: 211px;" />
-<pre>
-<strong>Input:</strong> darts = [[-2,0],[2,0],[0,2],[0,-2]], r = 2
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Circle dartboard with center in (0,0) and radius = 2 contain all points.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/04/29/sample_2_1806.png" style="width: 306px; height: 244px;" />
-<pre>
-<strong>Input:</strong> darts = [[-3,0],[3,0],[2,6],[5,4],[0,9],[7,8]], r = 5
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Circle dartboard with center in (0,4) and radius = 5 contain all points except the point (7,8).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= darts.length &lt;= 100</code></li>
-	<li><code>darts[i].length == 2</code></li>
-	<li><code>-10<sup>4</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= r &lt;= 5000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If there is an optimal solution, you can always move the circle so that two points lie on the boundary of the circle.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When the radius is fixed, you can find either 0 or 1 or 2 circles that pass two given points at the same time.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Loop for each pair of points and find the center of the circle, after that count the number of points inside the circle.
-</details>
diff --git a/problems/maximum-number-of-eaten-apples/README.md b/problems/maximum-number-of-eaten-apples/README.md
deleted file mode 100644
index 4d83aebe7..000000000
--- a/problems/maximum-number-of-eaten-apples/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../determine-if-string-halves-are-alike "Determine if String Halves Are Alike")
-　　　　　　　　　　　　　　　　
-[Next >](../where-will-the-ball-fall "Where Will the Ball Fall")
-
-## [1705. Maximum Number of Eaten Apples (Medium)](https://leetcode.com/problems/maximum-number-of-eaten-apples "吃苹果的最大数目")
-
-<p>There is a special kind of apple tree that grows apples every day for <code>n</code> days. On the <code>i<sup>th</sup></code> day, the tree grows <code>apples[i]</code> apples that will rot after <code>days[i]</code> days, that is on day <code>i + days[i]</code> the apples will be rotten and cannot be eaten. On some days, the apple tree does not grow any apples, which are denoted by <code>apples[i] == 0</code> and <code>days[i] == 0</code>.</p>
-
-<p>You decided to eat <strong>at most</strong> one apple a day (to keep the doctors away). Note that you can keep eating after the first <code>n</code> days.</p>
-
-<p>Given two integer arrays <code>days</code> and <code>apples</code> of length <code>n</code>, return <em>the maximum number of apples you can eat.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> apples = [1,2,3,5,2], days = [3,2,1,4,2]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> You can eat 7 apples:
-- On the first day, you eat an apple that grew on the first day.
-- On the second day, you eat an apple that grew on the second day.
-- On the third day, you eat an apple that grew on the second day. After this day, the apples that grew on the third day rot.
-- On the fourth to the seventh days, you eat apples that grew on the fourth day.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> apples = [3,0,0,0,0,2], days = [3,0,0,0,0,2]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> You can eat 5 apples:
-- On the first to the third day you eat apples that grew on the first day.
-- Do nothing on the fouth and fifth days.
-- On the sixth and seventh days you eat apples that grew on the sixth day.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == apples.length == days.length</code></li>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= apples[i], days[i] &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>days[i] = 0</code> if and only if <code>apples[i] = 0</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-It's optimal to finish the apples that will rot first before those that will rot last
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You need a structure to keep the apples sorted by their finish time
-</details>
diff --git a/problems/maximum-number-of-events-that-can-be-attended-ii/README.md b/problems/maximum-number-of-events-that-can-be-attended-ii/README.md
deleted file mode 100644
index dc8c37595..000000000
--- a/problems/maximum-number-of-events-that-can-be-attended-ii/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-length-of-string-after-deleting-similar-ends "Minimum Length of String After Deleting Similar Ends")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-array-is-sorted-and-rotated "Check if Array Is Sorted and Rotated")
-
-## [1751. Maximum Number of Events That Can Be Attended II (Hard)](https://leetcode.com/problems/maximum-number-of-events-that-can-be-attended-ii "最多可以参加的会议数目 II")
-
-<p>You are given an array of <code>events</code> where <code>events[i] = [startDay<sub>i</sub>, endDay<sub>i</sub>, value<sub>i</sub>]</code>. The <code>i<sup>th</sup></code> event starts at <code>startDay<sub>i</sub></code><sub> </sub>and ends at <code>endDay<sub>i</sub></code>, and if you attend this event, you will receive a value of <code>value<sub>i</sub></code>. You are also given an integer <code>k</code> which represents the maximum number of events you can attend.</p>
-
-<p>You can only attend one event at a time. If you choose to attend an event, you must attend the <strong>entire</strong> event. Note that the end day is <strong>inclusive</strong>: that is, you cannot attend two events where one of them starts and the other ends on the same day.</p>
-
-<p>Return <em>the <strong>maximum sum</strong> of values that you can receive by attending events.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/01/10/screenshot-2021-01-11-at-60048-pm.png" style="width: 400px; height: 103px;" /></p>
-
-<pre>
-<strong>Input:</strong> events = [[1,2,4],[3,4,3],[2,3,1]], k = 2
-<strong>Output:</strong> 7
-<strong>Explanation: </strong>Choose the green events, 0 and 1 (0-indexed) for a total value of 4 + 3 = 7.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/01/10/screenshot-2021-01-11-at-60150-pm.png" style="width: 400px; height: 103px;" /></p>
-
-<pre>
-<strong>Input:</strong> events = [[1,2,4],[3,4,3],[2,3,10]], k = 2
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> Choose event 2 for a total value of 10.
-Notice that you cannot attend any other event as they overlap, and that you do <strong>not</strong> have to attend k events.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2021/01/10/screenshot-2021-01-11-at-60703-pm.png" style="width: 400px; height: 126px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> events = [[1,1,1],[2,2,2],[3,3,3],[4,4,4]], k = 3
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> Although the events do not overlap, you can only attend 3 events. Pick the highest valued three.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= events.length</code></li>
-	<li><code>1 &lt;= k * events.length &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= startDay<sub>i</sub> &lt;= endDay<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= value<sub>i</sub> &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the events by its startTime.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For every event, you can either choose it and consider the next event available, or you can ignore it. You can efficiently find the next event that is available using binary search.
-</details>
diff --git a/problems/maximum-number-of-events-that-can-be-attended/README.md b/problems/maximum-number-of-events-that-can-be-attended/README.md
deleted file mode 100644
index 1db35bebc..000000000
--- a/problems/maximum-number-of-events-that-can-be-attended/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../product-of-the-last-k-numbers "Product of the Last K Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-target-array-with-multiple-sums "Construct Target Array With Multiple Sums")
-
-## [1353. Maximum Number of Events That Can Be Attended (Medium)](https://leetcode.com/problems/maximum-number-of-events-that-can-be-attended "最多可以参加的会议数目")
-
-<p>You are given an array of <code>events</code> where <code>events[i] = [startDay<sub>i</sub>, endDay<sub>i</sub>]</code>. Every event <code>i</code> starts at <code>startDay<sub>i</sub></code><sub> </sub>and ends at <code>endDay<sub>i</sub></code>.</p>
-
-<p>You can attend an event <code>i</code> at any day <code>d</code> where <code>startTime<sub>i</sub> &lt;= d &lt;= endTime<sub>i</sub></code>. You can only attend one event at any time <code>d</code>.</p>
-
-<p>Return <em>the maximum number of events you can attend</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/05/e1.png" style="width: 400px; height: 267px;" />
-<pre>
-<strong>Input:</strong> events = [[1,2],[2,3],[3,4]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You can attend all the three events.
-One way to attend them all is as shown.
-Attend the first event on day 1.
-Attend the second event on day 2.
-Attend the third event on day 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> events= [[1,2],[2,3],[3,4],[1,2]]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= events.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>events[i].length == 2</code></li>
-	<li><code>1 &lt;= startDay<sub>i</sub> &lt;= endDay<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the events by the start time and in case of tie by the end time in ascending order.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop over the sorted events. Attend as much as you can and keep the last day occupied. When you try to attend new event keep in mind the first day you can attend a new event in.
-</details>
diff --git a/problems/maximum-number-of-groups-getting-fresh-donuts/README.md b/problems/maximum-number-of-groups-getting-fresh-donuts/README.md
deleted file mode 100644
index 415e129b0..000000000
--- a/problems/maximum-number-of-groups-getting-fresh-donuts/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-nice-pairs-in-an-array "Count Nice Pairs in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../truncate-sentence "Truncate Sentence")
-
-## [1815. Maximum Number of Groups Getting Fresh Donuts (Hard)](https://leetcode.com/problems/maximum-number-of-groups-getting-fresh-donuts "得到新鲜甜甜圈的最多组数")
-
-<p>There is a donuts shop that bakes donuts in batches of <code>batchSize</code>. They have a rule where they must serve <strong>all</strong> of the donuts of a batch before serving any donuts of the next batch. You are given an integer <code>batchSize</code> and an integer array <code>groups</code>, where <code>groups[i]</code> denotes that there is a group of <code>groups[i]</code> customers that will visit the shop. Each customer will get exactly one donut.</p>
-
-<p>When a group visits the shop, all customers of the group must be served before serving any of the following groups. A group will be happy if they all get fresh donuts. That is, the first customer of the group does not receive a donut that was left over from the previous group.</p>
-
-<p>You can freely rearrange the ordering of the groups. Return <em>the <strong>maximum</strong> possible number of happy groups after rearranging the groups.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> batchSize = 3, groups = [1,2,3,4,5,6]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> You can arrange the groups as [6,2,4,5,1,3]. Then the 1<sup>st</sup>, 2<sup>nd</sup>, 4<sup>th</sup>, and 6<sup>th</sup> groups will be happy.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> batchSize = 4, groups = [1,3,2,5,2,2,1,6]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= batchSize &lt;= 9</code></li>
-	<li><code>1 &lt;= groups.length &lt;= 30</code></li>
-	<li><code>1 &lt;= groups[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The maximum number of happy groups is the maximum number of partitions you can split the groups into such that the sum of group sizes in each partition is 0 mod batchSize. At most one partition is allowed to have a different remainder (the first group will get fresh donuts anyway).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Suppose you have an array freq of length k where freq[i] = number of groups of size i mod batchSize. How can you utilize this in a dp solution?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Make a DP state dp[freq][r] that represents "the maximum number of partitions you can form given the current freq and current remainder r". You can hash the freq array to store it more easily in the dp table.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For each i from 0 to batchSize-1, the next DP state is dp[freq`][(r+i)%batchSize] where freq` is freq but with freq[i] decremented by 1. Take the largest of all of the next states and store it in ans. If r == 0, then return ans+1 (because you can form a new partition), otherwise return ans (continuing the current partition).
-</details>
diff --git a/problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target/README.md b/problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target/README.md
deleted file mode 100644
index e7e645d7d..000000000
--- a/problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-kth-bit-in-nth-binary-string "Find Kth Bit in Nth Binary String")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-cut-a-stick "Minimum Cost to Cut a Stick")
-
-## [1546. Maximum Number of Non-Overlapping Subarrays With Sum Equals Target (Medium)](https://leetcode.com/problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target "和为目标值且不重叠的非空子数组的最大数目")
-
-<p>Given an array <code>nums</code> and an integer <code>target</code>, return <em>the maximum number of <strong>non-empty</strong> <strong>non-overlapping</strong> subarrays such that the sum of values in each subarray is equal to</em> <code>target</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,1,1], target = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are 2 non-overlapping subarrays [<strong>1,1</strong>,1,<strong>1,1</strong>] with sum equals to target(2).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,3,5,1,4,2,-9], target = 6
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are 3 subarrays with sum equal to 6.
-([5,1], [4,2], [3,5,1,4,2,-9]) but only the first 2 are non-overlapping.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= target &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep track of prefix sums to quickly look up what subarray that sums "target" can be formed at each step of scanning the input array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-It can be proved that greedily forming valid subarrays as soon as one is found is optimal.
-</details>
diff --git a/problems/maximum-number-of-non-overlapping-substrings/README.md b/problems/maximum-number-of-non-overlapping-substrings/README.md
deleted file mode 100644
index 2fb424741..000000000
--- a/problems/maximum-number-of-non-overlapping-substrings/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-nodes-in-the-sub-tree-with-the-same-label "Number of Nodes in the Sub-Tree With the Same Label")
-　　　　　　　　　　　　　　　　
-[Next >](../find-a-value-of-a-mysterious-function-closest-to-target "Find a Value of a Mysterious Function Closest to Target")
-
-## [1520. Maximum Number of Non-Overlapping Substrings (Hard)](https://leetcode.com/problems/maximum-number-of-non-overlapping-substrings "最多的不重叠子字符串")
-
-<p>Given a string <code>s</code>&nbsp;of lowercase letters, you need to find the maximum number of <strong>non-empty</strong> substrings of&nbsp;<code>s</code>&nbsp;that meet the following conditions:</p>
-
-<ol>
-	<li>The substrings do not overlap, that is for any two substrings <code>s[i..j]</code> and <code>s[k..l]</code>, either <code>j &lt; k</code> or <code>i &gt; l</code>&nbsp;is true.</li>
-	<li>A substring that contains a certain character&nbsp;<code>c</code>&nbsp;must also contain all occurrences of <code>c</code>.</li>
-</ol>
-
-<p>Find <em>the maximum number of substrings that meet the above conditions</em>. If there are multiple solutions with the same number of substrings, <em>return the one with minimum total length.&nbsp;</em>It can be shown that there exists a unique solution of minimum total length.</p>
-
-<p>Notice that you can return the substrings in <strong>any</strong> order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;adefaddaccc&quot;
-<strong>Output:</strong> [&quot;e&quot;,&quot;f&quot;,&quot;ccc&quot;]
-<b>Explanation:</b>&nbsp;The following are all the possible substrings that meet the conditions:
-[
-&nbsp; &quot;adefaddaccc&quot;
-&nbsp; &quot;adefadda&quot;,
-&nbsp; &quot;ef&quot;,
-&nbsp; &quot;e&quot;,
-  &quot;f&quot;,
-&nbsp; &quot;ccc&quot;,
-]
-If we choose the first string, we cannot choose anything else and we&#39;d get only 1. If we choose &quot;adefadda&quot;, we are left with &quot;ccc&quot; which is the only one that doesn&#39;t overlap, thus obtaining 2 substrings. Notice also, that it&#39;s not optimal to choose &quot;ef&quot; since it can be split into two. Therefore, the optimal way is to choose [&quot;e&quot;,&quot;f&quot;,&quot;ccc&quot;] which gives us 3 substrings. No other solution of the same number of substrings exist.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abbaccd&quot;
-<strong>Output:</strong> [&quot;d&quot;,&quot;bb&quot;,&quot;cc&quot;]
-<b>Explanation: </b>Notice that while the set of substrings [&quot;d&quot;,&quot;abba&quot;,&quot;cc&quot;] also has length 3, it&#39;s considered incorrect since it has larger total length.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10^5</code></li>
-	<li><code>s</code>&nbsp;contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Notice that it's impossible for any two valid substrings to overlap unless one is inside another.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can start by finding the starting and ending index for each character.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-From these indices, we can form the substrings by expanding each character's range if necessary (if another character exists in the range with smaller/larger starting/ending index).
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Sort the valid substrings by length and greedily take those with the smallest length, discarding the ones that overlap those we took.
-</details>
diff --git a/problems/maximum-number-of-occurrences-of-a-substring/README.md b/problems/maximum-number-of-occurrences-of-a-substring/README.md
deleted file mode 100644
index c8a0ba0fb..000000000
--- a/problems/maximum-number-of-occurrences-of-a-substring/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../divide-array-in-sets-of-k-consecutive-numbers "Divide Array in Sets of K Consecutive Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-candies-you-can-get-from-boxes "Maximum Candies You Can Get from Boxes")
-
-## [1297. Maximum Number of Occurrences of a Substring (Medium)](https://leetcode.com/problems/maximum-number-of-occurrences-of-a-substring "子串的最大出现次数")
-
-<p>Given a string <code>s</code>, return the maximum number of ocurrences of <strong>any</strong> substring under the following rules:</p>
-
-<ul>
-	<li>The number of unique characters in the substring must be less than or equal to <code>maxLetters</code>.</li>
-	<li>The substring size must be between <code>minSize</code> and <code>maxSize</code> inclusive.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aababcaab&quot;, maxLetters = 2, minSize = 3, maxSize = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Substring &quot;aab&quot; has 2 ocurrences in the original string.
-It satisfies the conditions, 2 unique letters and size 3 (between minSize and maxSize).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaaa&quot;, maxLetters = 1, minSize = 3, maxSize = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Substring &quot;aaa&quot; occur 2 times in the string. It can overlap.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= maxLetters &lt;= 26</code></li>
-	<li><code>1 &lt;= minSize &lt;= maxSize &lt;= min(26, s.length)</code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check out the constraints, (maxSize <=26).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-This means you can explore all substrings in O(n * 26).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Find the Maximum Number of Occurrences of a Substring with bruteforce.
-</details>
diff --git a/problems/maximum-number-of-ones/README.md b/problems/maximum-number-of-ones/README.md
deleted file mode 100644
index dca5bed9c..000000000
--- a/problems/maximum-number-of-ones/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-distance-to-target-color "Shortest Distance to Target Color")
-　　　　　　　　　　　　　　　　
-[Next >](../distance-between-bus-stops "Distance Between Bus Stops")
-
-## [1183. Maximum Number of Ones (Hard)](https://leetcode.com/problems/maximum-number-of-ones "矩阵中 1 的最大数量")
-
-<p>Consider a matrix <code>M</code> with dimensions <code>width * height</code>, such that every cell has value <code>0</code>&nbsp;or <code>1</code>, and any <strong>square</strong>&nbsp;sub-matrix of <code>M</code> of size <code>sideLength * sideLength</code>&nbsp;has at most <code>maxOnes</code>&nbsp;ones.</p>
-
-<p>Return the maximum possible number of ones that the matrix <code>M</code> can have.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> width = 3, height = 3, sideLength = 2, maxOnes = 1
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-In a 3*3 matrix, no 2*2 sub-matrix can have more than 1 one.
-The best solution that has 4 ones is:
-[1,0,1]
-[0,0,0]
-[1,0,1]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> width = 3, height = 3, sideLength = 2, maxOnes = 2
-<strong>Output:</strong> 6
-<strong>Explanation:</strong>
-[1,0,1]
-[1,0,1]
-[1,0,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= width, height &lt;= 100</code></li>
-	<li><code>1 &lt;= sideLength &lt;= width, height</code></li>
-	<li><code>0 &lt;= maxOnes &lt;= sideLength * sideLength</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think of a greedy mathematical solution.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Say you choose to set some cell (i, j) to 1, all cells (x, y) such that i % sideLength == x % sideLength and j % sideLength == y % sideLength can also be set to 1 without increasing the max number of ones in a sub-matrix.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-In one move, choose to set all the cells with some modulus (i % sideLength, j % sideLength) to 1.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Choose the cells with max frequency.
-</details>
diff --git a/problems/maximum-number-of-people-that-can-be-caught-in-tag/README.md b/problems/maximum-number-of-people-that-can-be-caught-in-tag/README.md
deleted file mode 100644
index bdce1b715..000000000
--- a/problems/maximum-number-of-people-that-can-be-caught-in-tag/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-cutoff-score-for-each-school "Find Cutoff Score for Each School")
-　　　　　　　　　　　　　　　　
-[Next >](../count-the-number-of-experiments "Count the Number of Experiments")
-
-## [1989. Maximum Number of People That Can Be Caught in Tag (Medium)](https://leetcode.com/problems/maximum-number-of-people-that-can-be-caught-in-tag "")
-
-
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to use as much of the range of a person who is "it" as possible.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the leftmost person who is "it" that has not caught anyone yet, and the leftmost person who is not "it" that has not been caught yet.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If the person who is not "it" can be caught, pair them together and repeat the process.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-If the person who is not "it" cannot be caught, and the person who is not "it" is on the left of the person who is "it", find the next leftmost person who is not "it".
-</details>
-
-<details>
-<summary>Hint 5</summary>
-If the person who is not "it" cannot be caught, and the person who is "it" is on the left of the person who is not "it", find the next leftmost person who is "it".
-</details>
diff --git a/problems/maximum-number-of-points-with-cost/README.md b/problems/maximum-number-of-points-with-cost/README.md
deleted file mode 100644
index 971d5b4e4..000000000
--- a/problems/maximum-number-of-points-with-cost/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-minimum-number-of-rungs "Add Minimum Number of Rungs")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-genetic-difference-query "Maximum Genetic Difference Query")
-
-## [1937. Maximum Number of Points with Cost (Medium)](https://leetcode.com/problems/maximum-number-of-points-with-cost "扣分后的最大得分")
-
-<p>You are given an <code>m x n</code> integer matrix <code>points</code> (<strong>0-indexed</strong>). Starting with <code>0</code> points, you want to <strong>maximize</strong> the number of points you can get from the matrix.</p>
-
-<p>To gain points, you must pick one cell in <strong>each row</strong>. Picking the cell at coordinates <code>(r, c)</code> will <strong>add</strong> <code>points[r][c]</code> to your score.</p>
-
-<p>However, you will lose points if you pick a cell too far from the cell that you picked in the previous row. For every two adjacent rows <code>r</code> and <code>r + 1</code> (where <code>0 &lt;= r &lt; m - 1</code>), picking cells at coordinates <code>(r, c<sub>1</sub>)</code> and <code>(r + 1, c<sub>2</sub>)</code> will <strong>subtract</strong> <code>abs(c<sub>1</sub> - c<sub>2</sub>)</code> from your score.</p>
-
-<p>Return <em>the <strong>maximum</strong> number of points you can achieve</em>.</p>
-
-<p><code>abs(x)</code> is defined as:</p>
-
-<ul>
-	<li><code>x</code> for <code>x &gt;= 0</code>.</li>
-	<li><code>-x</code> for <code>x &lt; 0</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong><strong> </strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/12/screenshot-2021-07-12-at-13-40-26-diagram-drawio-diagrams-net.png" style="width: 300px; height: 300px;" />
-<pre>
-<strong>Input:</strong> points = [[1,2,3],[1,5,1],[3,1,1]]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong>
-The blue cells denote the optimal cells to pick, which have coordinates (0, 2), (1, 1), and (2, 0).
-You add 3 + 5 + 3 = 11 to your score.
-However, you must subtract abs(2 - 1) + abs(1 - 0) = 2 from your score.
-Your final score is 11 - 2 = 9.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/12/screenshot-2021-07-12-at-13-42-14-diagram-drawio-diagrams-net.png" style="width: 200px; height: 299px;" />
-<pre>
-<strong>Input:</strong> points = [[1,5],[2,3],[4,2]]
-<strong>Output:</strong> 11
-<strong>Explanation:</strong>
-The blue cells denote the optimal cells to pick, which have coordinates (0, 1), (1, 1), and (2, 0).
-You add 5 + 3 + 4 = 12 to your score.
-However, you must subtract abs(1 - 1) + abs(1 - 0) = 1 from your score.
-Your final score is 12 - 1 = 11.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == points.length</code></li>
-	<li><code>n == points[r].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= m * n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= points[r][c] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try using dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-dp[i][j] is the maximum number of points you can have if points[i][j] is the most recent cell you picked.
-</details>
diff --git a/problems/maximum-number-of-removable-characters/README.md b/problems/maximum-number-of-removable-characters/README.md
deleted file mode 100644
index 6dc55f65c..000000000
--- a/problems/maximum-number-of-removable-characters/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../redistribute-characters-to-make-all-strings-equal "Redistribute Characters to Make All Strings Equal")
-　　　　　　　　　　　　　　　　
-[Next >](../merge-triplets-to-form-target-triplet "Merge Triplets to Form Target Triplet")
-
-## [1898. Maximum Number of Removable Characters (Medium)](https://leetcode.com/problems/maximum-number-of-removable-characters "可移除字符的最大数目")
-
-<p>You are given two strings <code>s</code> and <code>p</code> where <code>p</code> is a <strong>subsequence </strong>of <code>s</code>. You are also given a <strong>distinct 0-indexed </strong>integer array <code>removable</code> containing a subset of indices of <code>s</code> (<code>s</code> is also <strong>0-indexed</strong>).</p>
-
-<p>You want to choose an integer <code>k</code> (<code>0 &lt;= k &lt;= removable.length</code>) such that, after removing <code>k</code> characters from <code>s</code> using the <strong>first</strong> <code>k</code> indices in <code>removable</code>, <code>p</code> is still a <strong>subsequence</strong> of <code>s</code>. More formally, you will mark the character at <code>s[removable[i]]</code> for each <code>0 &lt;= i &lt; k</code>, then remove all marked characters and check if <code>p</code> is still a subsequence.</p>
-
-<p>Return <em>the <strong>maximum</strong> </em><code>k</code><em> you can choose such that </em><code>p</code><em> is still a <strong>subsequence</strong> of </em><code>s</code><em> after the removals</em>.</p>
-
-<p>A <strong>subsequence</strong> of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcacb&quot;, p = &quot;ab&quot;, removable = [3,1,0]
-<strong>Output:</strong> 2
-<strong>Explanation</strong>: After removing the characters at indices 3 and 1, &quot;a<s><strong>b</strong></s>c<s><strong>a</strong></s>cb&quot; becomes &quot;accb&quot;.
-&quot;ab&quot; is a subsequence of &quot;<strong><u>a</u></strong>cc<strong><u>b</u></strong>&quot;.
-If we remove the characters at indices 3, 1, and 0, &quot;<s><strong>ab</strong></s>c<s><strong>a</strong></s>cb&quot; becomes &quot;ccb&quot;, and &quot;ab&quot; is no longer a subsequence.
-Hence, the maximum k is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcbddddd&quot;, p = &quot;abcd&quot;, removable = [3,2,1,4,5,6]
-<strong>Output:</strong> 1
-<strong>Explanation</strong>: After removing the character at index 3, &quot;abc<s><strong>b</strong></s>ddddd&quot; becomes &quot;abcddddd&quot;.
-&quot;abcd&quot; is a subsequence of &quot;<u><strong>abcd</strong></u>dddd&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcab&quot;, p = &quot;abc&quot;, removable = [0,1,2,3,4]
-<strong>Output:</strong> 0
-<strong>Explanation</strong>: If you remove the first index in the array removable, &quot;abc&quot; is no longer a subsequence.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= p.length &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= removable.length &lt; s.length</code></li>
-	<li><code>0 &lt;= removable[i] &lt; s.length</code></li>
-	<li><code>p</code> is a <strong>subsequence</strong> of <code>s</code>.</li>
-	<li><code>s</code> and <code>p</code> both consist of lowercase English letters.</li>
-	<li>The elements in <code>removable</code> are <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First, we need to think about solving an easier problem, If we remove a set of indices from the string does P exist in S as a subsequence
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can binary search the K and check by solving the above problem.
-</details>
diff --git a/problems/maximum-number-of-tasks-you-can-assign/README.md b/problems/maximum-number-of-tasks-you-can-assign/README.md
deleted file mode 100644
index 03bd179c2..000000000
--- a/problems/maximum-number-of-tasks-you-can-assign/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../most-beautiful-item-for-each-query "Most Beautiful Item for Each Query")
-　　　　　　　　　　　　　　　　
-[Next >](../the-winner-university "The Winner University")
-
-## [2071. Maximum Number of Tasks You Can Assign (Hard)](https://leetcode.com/problems/maximum-number-of-tasks-you-can-assign "你可以安排的最多任务数目")
-
-<p>You have <code>n</code> tasks and <code>m</code> workers. Each task has a strength requirement stored in a <strong>0-indexed</strong> integer array <code>tasks</code>, with the <code>i<sup>th</sup></code> task requiring <code>tasks[i]</code> strength to complete. The strength of each worker is stored in a <strong>0-indexed</strong> integer array <code>workers</code>, with the <code>j<sup>th</sup></code> worker having <code>workers[j]</code> strength. Each worker can only be assigned to a <strong>single</strong> task and must have a strength <strong>greater than or equal</strong> to the task&#39;s strength requirement (i.e., <code>workers[j] &gt;= tasks[i]</code>).</p>
-
-<p>Additionally, you have <code>pills</code> magical pills that will <strong>increase a worker&#39;s strength</strong> by <code>strength</code>. You can decide which workers receive the magical pills, however, you may only give each worker <strong>at most one</strong> magical pill.</p>
-
-<p>Given the <strong>0-indexed </strong>integer arrays <code>tasks</code> and <code>workers</code> and the integers <code>pills</code> and <code>strength</code>, return <em>the <strong>maximum</strong> number of tasks that can be completed.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [<u><strong>3</strong></u>,<u><strong>2</strong></u>,<u><strong>1</strong></u>], workers = [<u><strong>0</strong></u>,<u><strong>3</strong></u>,<u><strong>3</strong></u>], pills = 1, strength = 1
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-We can assign the magical pill and tasks as follows:
-- Give the magical pill to worker 0.
-- Assign worker 0 to task 2 (0 + 1 &gt;= 1)
-- Assign worker 1 to task 1 (3 &gt;= 2)
-- Assign worker 2 to task 0 (3 &gt;= 3)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [<u><strong>5</strong></u>,4], workers = [<u><strong>0</strong></u>,0,0], pills = 1, strength = 5
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-We can assign the magical pill and tasks as follows:
-- Give the magical pill to worker 0.
-- Assign worker 0 to task 0 (0 + 5 &gt;= 5)
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [<u><strong>10</strong></u>,<u><strong>15</strong></u>,30], workers = [<u><strong>0</strong></u>,<u><strong>10</strong></u>,10,10,10], pills = 3, strength = 10
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-We can assign the magical pills and tasks as follows:
-- Give the magical pill to worker 0 and worker 1.
-- Assign worker 0 to task 0 (0 + 10 &gt;= 10)
-- Assign worker 1 to task 1 (10 + 10 &gt;= 15)
-The last pill is not given because it will not make any worker strong enough for the last task.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == tasks.length</code></li>
-	<li><code>m == workers.length</code></li>
-	<li><code>1 &lt;= n, m &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= pills &lt;= m</code></li>
-	<li><code>0 &lt;= tasks[i], workers[j], strength &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Monotonic Queue](../../tag/monotonic-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is it possible to assign the first k smallest tasks to the workers?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can you efficiently try every k?
-</details>
diff --git a/problems/maximum-number-of-visible-points/README.md b/problems/maximum-number-of-visible-points/README.md
deleted file mode 100644
index f9401d886..000000000
--- a/problems/maximum-number-of-visible-points/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../even-odd-tree "Even Odd Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-one-bit-operations-to-make-integers-zero "Minimum One Bit Operations to Make Integers Zero")
-
-## [1610. Maximum Number of Visible Points (Hard)](https://leetcode.com/problems/maximum-number-of-visible-points "可见点的最大数目")
-
-<p>You are given an array <code>points</code>, an integer <code>angle</code>, and your <code>location</code>, where <code>location = [pos<sub>x</sub>, pos<sub>y</sub>]</code> and <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> both denote <strong>integral coordinates</strong> on the X-Y plane.</p>
-
-<p>Initially, you are facing directly east from your position. You <strong>cannot move</strong> from your position, but you can <strong>rotate</strong>. In other words, <code>pos<sub>x</sub></code> and <code>pos<sub>y</sub></code> cannot be changed. Your field of view in <strong>degrees</strong> is represented by <code>angle</code>, determining how wide you can see from any given view direction. Let <code>d</code> be the amount in degrees that you rotate counterclockwise. Then, your field of view is the <strong>inclusive</strong> range of angles <code>[d - angle/2, d + angle/2]</code>.</p>
-
-<p>
-<video autoplay="" controls="" height="360" muted="" style="max-width:100%;height:auto;" width="480"><source src="https://assets.leetcode.com/uploads/2020/09/30/angle.mp4" type="video/mp4" />Your browser does not support the video tag or this video format.</video>
-</p>
-
-<p>You can <strong>see</strong> some set of points if, for each point, the <strong>angle</strong> formed by the point, your position, and the immediate east direction from your position is <strong>in your field of view</strong>.</p>
-
-<p>There can be multiple points at one coordinate. There may be points at your location, and you can always see these points regardless of your rotation. Points do not obstruct your vision to other points.</p>
-
-<p>Return <em>the maximum number of points you can see</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/30/89a07e9b-00ab-4967-976a-c723b2aa8656.png" style="width: 400px; height: 300px;" />
-<pre>
-<strong>Input:</strong> points = [[2,1],[2,2],[3,3]], angle = 90, location = [1,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The shaded region represents your field of view. All points can be made visible in your field of view, including [3,3] even though [2,2] is in front and in the same line of sight.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[2,1],[2,2],[3,4],[1,1]], angle = 90, location = [1,1]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> All points can be made visible in your field of view, including the one at your location.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/30/5010bfd3-86e6-465f-ac64-e9df941d2e49.png" style="width: 690px; height: 348px;" />
-<pre>
-<strong>Input:</strong> points = [[1,0],[2,1]], angle = 13, location = [1,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You can only see one of the two points, as shown above.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= points.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>location.length == 2</code></li>
-	<li><code>0 &lt;= angle &lt; 360</code></li>
-	<li><code>0 &lt;= pos<sub>x</sub>, pos<sub>y</sub>, x<sub>i</sub>, y<sub>i</sub> &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the points by polar angle with the original position. Now only a consecutive collection of points would be visible from any coordinate.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can use two pointers to keep track of visible points for each start point
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For handling the cyclic condition, it’d be helpful to append the point list to itself after sorting.
-</details>
diff --git a/problems/maximum-number-of-vowels-in-a-substring-of-given-length/README.md b/problems/maximum-number-of-vowels-in-a-substring-of-given-length/README.md
deleted file mode 100644
index 0222974a8..000000000
--- a/problems/maximum-number-of-vowels-in-a-substring-of-given-length/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence "Check If a Word Occurs As a Prefix of Any Word in a Sentence")
-　　　　　　　　　　　　　　　　
-[Next >](../pseudo-palindromic-paths-in-a-binary-tree "Pseudo-Palindromic Paths in a Binary Tree")
-
-## [1456. Maximum Number of Vowels in a Substring of Given Length (Medium)](https://leetcode.com/problems/maximum-number-of-vowels-in-a-substring-of-given-length "定长子串中元音的最大数目")
-
-<p>Given a string <code>s</code> and an integer <code>k</code>, return <em>the maximum number of vowel letters in any substring of </em><code>s</code><em> with length </em><code>k</code>.</p>
-
-<p><strong>Vowel letters</strong> in English are <code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, and <code>&#39;u&#39;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abciiidef&quot;, k = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The substring &quot;iii&quot; contains 3 vowel letters.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aeiou&quot;, k = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Any substring of length 2 contains 2 vowels.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;, k = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> &quot;lee&quot;, &quot;eet&quot; and &quot;ode&quot; contain 2 vowels.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-	<li><code>1 &lt;= k &lt;= s.length</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep a window of size k and maintain the number of vowels in it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep moving the window and update the number of vowels while moving. Answer is max number of vowels of any window.
-</details>
diff --git a/problems/maximum-number-of-ways-to-partition-an-array/README.md b/problems/maximum-number-of-ways-to-partition-an-array/README.md
deleted file mode 100644
index 9ab28a83d..000000000
--- a/problems/maximum-number-of-ways-to-partition-an-array/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximize-the-confusion-of-an-exam "Maximize the Confusion of an Exam")
-　　　　　　　　　　　　　　　　
-[Next >](../low-quality-problems "Low-Quality Problems")
-
-## [2025. Maximum Number of Ways to Partition an Array (Hard)](https://leetcode.com/problems/maximum-number-of-ways-to-partition-an-array "分割数组的最多方案数")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code> of length <code>n</code>. The number of ways to <strong>partition</strong> <code>nums</code> is the number of <code>pivot</code> indices that satisfy both conditions:</p>
-
-<ul>
-	<li><code>1 &lt;= pivot &lt; n</code></li>
-	<li><code>nums[0] + nums[1] + ... + nums[pivot - 1] == nums[pivot] + nums[pivot + 1] + ... + nums[n - 1]</code></li>
-</ul>
-
-<p>You are also given an integer <code>k</code>. You can choose to change the value of <strong>one</strong> element of <code>nums</code> to <code>k</code>, or to leave the array <strong>unchanged</strong>.</p>
-
-<p>Return <em>the <strong>maximum</strong> possible number of ways to <strong>partition</strong> </em><code>nums</code><em> to satisfy both conditions after changing <strong>at most</strong> one element</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,-1,2], k = 3
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> One optimal approach is to change nums[0] to k. The array becomes [<strong><u>3</u></strong>,-1,2].
-There is one way to partition the array:
-- For pivot = 2, we have the partition [3,-1 | 2]: 3 + -1 == 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,0], k = 1
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The optimal approach is to leave the array unchanged.
-There are two ways to partition the array:
-- For pivot = 1, we have the partition [0 | 0,0]: 0 == 0 + 0.
-- For pivot = 2, we have the partition [0,0 | 0]: 0 + 0 == 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [22,4,-25,-20,-15,15,-16,7,19,-10,0,-13,-14], k = -33
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> One optimal approach is to change nums[2] to k. The array becomes [22,4,<u><strong>-33</strong></u>,-20,-15,15,-16,7,19,-10,0,-13,-14].
-There are four ways to partition the array.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= k, nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A pivot point splits the array into equal prefix and suffix. If no change is made to the array, the goal is to find the number of pivot p such that prefix[p-1] == suffix[p].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Consider how prefix and suffix will change when we change a number nums[i] to k.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-When sweeping through each element, can you find the total number of pivots where the difference of prefix and suffix happens to equal to the changes of k-nums[i].
-</details>
diff --git a/problems/maximum-number-of-weeks-for-which-you-can-work/README.md b/problems/maximum-number-of-weeks-for-which-you-can-work/README.md
deleted file mode 100644
index 406210336..000000000
--- a/problems/maximum-number-of-weeks-for-which-you-can-work/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../three-divisors "Three Divisors")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-garden-perimeter-to-collect-enough-apples "Minimum Garden Perimeter to Collect Enough Apples")
-
-## [1953. Maximum Number of Weeks for Which You Can Work (Medium)](https://leetcode.com/problems/maximum-number-of-weeks-for-which-you-can-work "你可以工作的最大周数")
-
-<p>There are <code>n</code> projects numbered from <code>0</code> to <code>n - 1</code>. You are given an integer array <code>milestones</code> where each <code>milestones[i]</code> denotes the number of milestones the <code>i<sup>th</sup></code> project has.</p>
-
-<p>You can work on the projects following these two rules:</p>
-
-<ul>
-	<li>Every week, you will finish <strong>exactly one</strong> milestone of <strong>one</strong> project. You&nbsp;<strong>must</strong>&nbsp;work every week.</li>
-	<li>You <strong>cannot</strong> work on two milestones from the same project for two <strong>consecutive</strong> weeks.</li>
-</ul>
-
-<p>Once all the milestones of all the projects are finished, or if the only milestones that you can work on will cause you to violate the above rules, you will <strong>stop working</strong>. Note that you may not be able to finish every project&#39;s milestones due to these constraints.</p>
-
-<p>Return <em>the <strong>maximum</strong> number of weeks you would be able to work on the projects without violating the rules mentioned above</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> milestones = [1,2,3]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> One possible scenario is:
-​​​​- During the 1<sup>st</sup> week, you will work on a milestone of project 0.
-- During the 2<sup>nd</sup> week, you will work on a milestone of project 2.
-- During the 3<sup>rd</sup> week, you will work on a milestone of project 1.
-- During the 4<sup>th</sup> week, you will work on a milestone of project 2.
-- During the 5<sup>th</sup> week, you will work on a milestone of project 1.
-- During the 6<sup>th</sup> week, you will work on a milestone of project 2.
-The total number of weeks is 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> milestones = [5,2,1]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> One possible scenario is:
-- During the 1<sup>st</sup> week, you will work on a milestone of project 0.
-- During the 2<sup>nd</sup> week, you will work on a milestone of project 1.
-- During the 3<sup>rd</sup> week, you will work on a milestone of project 0.
-- During the 4<sup>th</sup> week, you will work on a milestone of project 1.
-- During the 5<sup>th</sup> week, you will work on a milestone of project 0.
-- During the 6<sup>th</sup> week, you will work on a milestone of project 2.
-- During the 7<sup>th</sup> week, you will work on a milestone of project 0.
-The total number of weeks is 7.
-Note that you cannot work on the last milestone of project 0 on 8<sup>th</sup> week because it would violate the rules.
-Thus, one milestone in project 0 will remain unfinished.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == milestones.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= milestones[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Task Scheduler](../task-scheduler) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Work on the project with the largest number of milestones as long as it is possible.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Does the project with the largest number of milestones affect the number of weeks?
-</details>
diff --git a/problems/maximum-number-of-words-found-in-sentences/README.md b/problems/maximum-number-of-words-found-in-sentences/README.md
deleted file mode 100644
index 38e5c6b31..000000000
--- a/problems/maximum-number-of-words-found-in-sentences/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../elements-in-array-after-removing-and-replacing-elements "Elements in Array After Removing and Replacing Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../find-all-possible-recipes-from-given-supplies "Find All Possible Recipes from Given Supplies")
-
-## [2114. Maximum Number of Words Found in Sentences (Easy)](https://leetcode.com/problems/maximum-number-of-words-found-in-sentences "句子中的最多单词数")
-
-<p>A <strong>sentence</strong> is a list of <strong>words</strong> that are separated by a single space&nbsp;with no leading or trailing spaces.</p>
-
-<p>You are given an array of strings <code>sentences</code>, where each <code>sentences[i]</code> represents a single <strong>sentence</strong>.</p>
-
-<p>Return <em>the <strong>maximum number of words</strong> that appear in a single sentence</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentences = [&quot;alice and bob love leetcode&quot;, &quot;i think so too&quot;, <u>&quot;this is great thanks very much&quot;</u>]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> 
-- The first sentence, &quot;alice and bob love leetcode&quot;, has 5 words in total.
-- The second sentence, &quot;i think so too&quot;, has 4 words in total.
-- The third sentence, &quot;this is great thanks very much&quot;, has 6 words in total.
-Thus, the maximum number of words in a single sentence comes from the third sentence, which has 6 words.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentences = [&quot;please wait&quot;, <u>&quot;continue to fight&quot;</u>, <u>&quot;continue to win&quot;</u>]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> It is possible that multiple sentences contain the same number of words. 
-In this example, the second and third sentences (underlined) have the same number of words.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= sentences.length &lt;= 100</code></li>
-	<li><code>1 &lt;= sentences[i].length &lt;= 100</code></li>
-	<li><code>sentences[i]</code> consists only of lowercase English letters and <code>&#39; &#39;</code> only.</li>
-	<li><code>sentences[i]</code> does not have leading or trailing spaces.</li>
-	<li>All the words in <code>sentences[i]</code> are separated by a single space.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Process each sentence separately and count the number of words by looking for the number of space characters in the sentence and adding it by 1.
-</details>
diff --git a/problems/maximum-number-of-words-you-can-type/README.md b/problems/maximum-number-of-words-you-can-type/README.md
deleted file mode 100644
index 2426e2dd3..000000000
--- a/problems/maximum-number-of-words-you-can-type/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../confirmation-rate "Confirmation Rate")
-　　　　　　　　　　　　　　　　
-[Next >](../add-minimum-number-of-rungs "Add Minimum Number of Rungs")
-
-## [1935. Maximum Number of Words You Can Type (Easy)](https://leetcode.com/problems/maximum-number-of-words-you-can-type "可以输入的最大单词数")
-
-<p>There is a malfunctioning keyboard where some letter keys do not work. All other keys on the keyboard work properly.</p>
-
-<p>Given a string <code>text</code> of words separated by a single space (no leading or trailing spaces) and a string <code>brokenLetters</code> of all <strong>distinct</strong> letter keys that are broken, return <em>the <strong>number of words</strong> in</em> <code>text</code> <em>you can fully type using this keyboard</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;hello world&quot;, brokenLetters = &quot;ad&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> We cannot type &quot;world&quot; because the &#39;d&#39; key is broken.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;leet code&quot;, brokenLetters = &quot;lt&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> We cannot type &quot;leet&quot; because the &#39;l&#39; and &#39;t&#39; keys are broken.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;leet code&quot;, brokenLetters = &quot;e&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> We cannot type either word because the &#39;e&#39; key is broken.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= text.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= brokenLetters.length &lt;= 26</code></li>
-	<li><code>text</code> consists of words separated by a single space without any leading or trailing spaces.</li>
-	<li>Each word only consists of lowercase English letters.</li>
-	<li><code>brokenLetters</code> consists of <strong>distinct</strong> lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check each word separately if it can be typed.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-A word can be typed if all its letters are not broken.
-</details>
diff --git a/problems/maximum-of-absolute-value-expression/README.md b/problems/maximum-of-absolute-value-expression/README.md
deleted file mode 100644
index 1ab54a71d..000000000
--- a/problems/maximum-of-absolute-value-expression/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-tree-from-leaf-values "Minimum Cost Tree From Leaf Values")
-　　　　　　　　　　　　　　　　
-[Next >](../reported-posts-ii "Reported Posts II")
-
-## [1131. Maximum of Absolute Value Expression (Medium)](https://leetcode.com/problems/maximum-of-absolute-value-expression "绝对值表达式的最大值")
-
-<p>Given two arrays of integers with equal lengths, return the maximum value of:</p>
-
-<p><code>|arr1[i] - arr1[j]| + |arr2[i] - arr2[j]| + |i - j|</code></p>
-
-<p>where the maximum is taken over all <code>0 &lt;= i, j &lt; arr1.length</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [1,2,3,4], arr2 = [-1,4,5,6]
-<strong>Output:</strong> 13
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [1,-2,-5,0,10], arr2 = [0,-2,-1,-7,-4]
-<strong>Output:</strong> 20
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr1.length == arr2.length &lt;= 40000</code></li>
-	<li><code>-10^6 &lt;= arr1[i], arr2[i] &lt;= 10^6</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use the idea that abs(A) + abs(B) = max(A+B, A-B, -A+B, -A-B).
-</details>
diff --git a/problems/maximum-of-minimum-values-in-all-subarrays/README.md b/problems/maximum-of-minimum-values-in-all-subarrays/README.md
deleted file mode 100644
index 2bad1050a..000000000
--- a/problems/maximum-of-minimum-values-in-all-subarrays/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../strong-friendship "Strong Friendship")
-　　　　　　　　　　　　　　　　
-[Next >](../all-the-pairs-with-the-maximum-number-of-common-followers "All the Pairs With the Maximum Number of Common Followers")
-
-## [1950. Maximum of Minimum Values in All Subarrays (Medium)](https://leetcode.com/problems/maximum-of-minimum-values-in-all-subarrays "所有子数组最小值中的最大值")
-
-
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Imagine the array is empty, and each element is coming to its index one by one, starting with the smallest element.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each coming element nums[i], calculate L and R, the indices of the first smallest elements on the left and the right respectively.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The answer of the queries from 1 to R-L+1 will be at least this element.
-</details>
diff --git a/problems/maximum-path-quality-of-a-graph/README.md b/problems/maximum-path-quality-of-a-graph/README.md
deleted file mode 100644
index 9e6c3bbfd..000000000
--- a/problems/maximum-path-quality-of-a-graph/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimized-maximum-of-products-distributed-to-any-store "Minimized Maximum of Products Distributed to Any Store")
-　　　　　　　　　　　　　　　　
-[Next >](../account-balance "Account Balance")
-
-## [2065. Maximum Path Quality of a Graph (Hard)](https://leetcode.com/problems/maximum-path-quality-of-a-graph "最大化一张图中的路径价值")
-
-<p>There is an <strong>undirected</strong> graph with <code>n</code> nodes numbered from <code>0</code> to <code>n - 1</code> (<strong>inclusive</strong>). You are given a <strong>0-indexed</strong> integer array <code>values</code> where <code>values[i]</code> is the <strong>value </strong>of the <code>i<sup>th</sup></code> node. You are also given a <strong>0-indexed</strong> 2D integer array <code>edges</code>, where each <code>edges[j] = [u<sub>j</sub>, v<sub>j</sub>, time<sub>j</sub>]</code> indicates that there is an undirected edge between the nodes <code>u<sub>j</sub></code> and <code>v<sub>j</sub></code>,<sub> </sub>and it takes <code>time<sub>j</sub></code> seconds to travel between the two nodes. Finally, you are given an integer <code>maxTime</code>.</p>
-
-<p>A <strong>valid</strong> <strong>path</strong> in the graph is any path that starts at node <code>0</code>, ends at node <code>0</code>, and takes <strong>at most</strong> <code>maxTime</code> seconds to complete. You may visit the same node multiple times. The <strong>quality</strong> of a valid path is the <strong>sum</strong> of the values of the <strong>unique nodes</strong> visited in the path (each node&#39;s value is added <strong>at most once</strong> to the sum).</p>
-
-<p>Return <em>the <strong>maximum</strong> quality of a valid path</em>.</p>
-
-<p><strong>Note:</strong> There are <strong>at most four</strong> edges connected to each node.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/19/ex1drawio.png" style="width: 269px; height: 170px;" />
-<pre>
-<strong>Input:</strong> values = [0,32,10,43], edges = [[0,1,10],[1,2,15],[0,3,10]], maxTime = 49
-<strong>Output:</strong> 75
-<strong>Explanation:</strong>
-One possible path is 0 -&gt; 1 -&gt; 0 -&gt; 3 -&gt; 0. The total time taken is 10 + 10 + 10 + 10 = 40 &lt;= 49.
-The nodes visited are 0, 1, and 3, giving a maximal path quality of 0 + 32 + 43 = 75.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/19/ex2drawio.png" style="width: 269px; height: 170px;" />
-<pre>
-<strong>Input:</strong> values = [5,10,15,20], edges = [[0,1,10],[1,2,10],[0,3,10]], maxTime = 30
-<strong>Output:</strong> 25
-<strong>Explanation:</strong>
-One possible path is 0 -&gt; 3 -&gt; 0. The total time taken is 10 + 10 = 20 &lt;= 30.
-The nodes visited are 0 and 3, giving a maximal path quality of 5 + 20 = 25.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/19/ex31drawio.png" style="width: 236px; height: 170px;" />
-<pre>
-<strong>Input:</strong> values = [1,2,3,4], edges = [[0,1,10],[1,2,11],[2,3,12],[1,3,13]], maxTime = 50
-<strong>Output:</strong> 7
-<strong>Explanation:</strong>
-One possible path is 0 -&gt; 1 -&gt; 3 -&gt; 1 -&gt; 0. The total time taken is 10 + 13 + 13 + 10 = 46 &lt;= 50.
-The nodes visited are 0, 1, and 3, giving a maximal path quality of 1 + 2 + 4 = 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == values.length</code></li>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>0 &lt;= values[i] &lt;= 10<sup>8</sup></code></li>
-	<li><code>0 &lt;= edges.length &lt;= 2000</code></li>
-	<li><code>edges[j].length == 3 </code></li>
-	<li><code>0 &lt;= u<sub>j </sub>&lt; v<sub>j</sub> &lt;= n - 1</code></li>
-	<li><code>10 &lt;= time<sub>j</sub>, maxTime &lt;= 100</code></li>
-	<li>All the pairs <code>[u<sub>j</sub>, v<sub>j</sub>]</code> are <strong>unique</strong>.</li>
-	<li>There are <strong>at most four</strong> edges connected to each node.</li>
-	<li>The graph may not be connected.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many nodes can you visit within maxTime seconds?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you try every valid path?
-</details>
diff --git a/problems/maximum-performance-of-a-team/README.md b/problems/maximum-performance-of-a-team/README.md
deleted file mode 100644
index 875210e17..000000000
--- a/problems/maximum-performance-of-a-team/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../balance-a-binary-search-tree "Balance a Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../total-sales-amount-by-year "Total Sales Amount by Year")
-
-## [1383. Maximum Performance of a Team (Hard)](https://leetcode.com/problems/maximum-performance-of-a-team "最大的团队表现值")
-
-<p>You are given two integers <code>n</code> and <code>k</code> and two integer arrays <code>speed</code> and <code>efficiency</code> both of length <code>n</code>. There are <code>n</code> engineers numbered from <code>1</code> to <code>n</code>. <code>speed[i]</code> and <code>efficiency[i]</code> represent the speed and efficiency of the <code>i<sup>th</sup></code> engineer respectively.</p>
-
-<p>Choose <strong>at most</strong> <code>k</code> different engineers out of the <code>n</code> engineers to form a team with the maximum <strong>performance</strong>.</p>
-
-<p>The performance of a team is the sum of their engineers&#39; speeds multiplied by the minimum efficiency among their engineers.</p>
-
-<p>Return <em>the maximum performance of this team</em>. Since the answer can be a huge number, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6, speed = [2,10,3,1,5,8], efficiency = [5,4,3,9,7,2], k = 2
-<strong>Output:</strong> 60
-<strong>Explanation:</strong> 
-We have the maximum performance of the team by selecting engineer 2 (with speed=10 and efficiency=4) and engineer 5 (with speed=5 and efficiency=7). That is, performance = (10 + 5) * min(4, 7) = 60.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6, speed = [2,10,3,1,5,8], efficiency = [5,4,3,9,7,2], k = 3
-<strong>Output:</strong> 68
-<strong>Explanation:
-</strong>This is the same example as the first but k = 3. We can select engineer 1, engineer 2 and engineer 5 to get the maximum performance of the team. That is, performance = (2 + 10 + 5) * min(5, 4, 7) = 68.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6, speed = [2,10,3,1,5,8], efficiency = [5,4,3,9,7,2], k = 4
-<strong>Output:</strong> 72
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>speed.length == n</code></li>
-	<li><code>efficiency.length == n</code></li>
-	<li><code>1 &lt;= speed[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= efficiency[i] &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Maximum Fruits Harvested After at Most K Steps](../maximum-fruits-harvested-after-at-most-k-steps) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep track of the engineers by their efficiency in decreasing order.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Starting from one engineer, to build a team, it suffices to bring K-1 more engineers who have higher efficiencies as well as high speeds.
-</details>
diff --git a/problems/maximum-points-you-can-obtain-from-cards/README.md b/problems/maximum-points-you-can-obtain-from-cards/README.md
deleted file mode 100644
index d01d36990..000000000
--- a/problems/maximum-points-you-can-obtain-from-cards/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-score-after-splitting-a-string "Maximum Score After Splitting a String")
-　　　　　　　　　　　　　　　　
-[Next >](../diagonal-traverse-ii "Diagonal Traverse II")
-
-## [1423. Maximum Points You Can Obtain from Cards (Medium)](https://leetcode.com/problems/maximum-points-you-can-obtain-from-cards "可获得的最大点数")
-
-<p>There are several cards <strong>arranged in a row</strong>, and each card has an associated number of points. The points are given in the integer array <code>cardPoints</code>.</p>
-
-<p>In one step, you can take one card from the beginning or from the end of the row. You have to take exactly <code>k</code> cards.</p>
-
-<p>Your score is the sum of the points of the cards you have taken.</p>
-
-<p>Given the integer array <code>cardPoints</code> and the integer <code>k</code>, return the <em>maximum score</em> you can obtain.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> cardPoints = [1,2,3,4,5,6,1], k = 3
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> After the first step, your score will always be 1. However, choosing the rightmost card first will maximize your total score. The optimal strategy is to take the three cards on the right, giving a final score of 1 + 6 + 5 = 12.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> cardPoints = [2,2,2], k = 2
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Regardless of which two cards you take, your score will always be 4.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> cardPoints = [9,7,7,9,7,7,9], k = 7
-<strong>Output:</strong> 55
-<strong>Explanation:</strong> You have to take all the cards. Your score is the sum of points of all cards.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= cardPoints.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= cardPoints[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= k &lt;= cardPoints.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Maximum Score from Performing Multiplication Operations](../maximum-score-from-performing-multiplication-operations) (Medium)
-  1. [Removing Minimum and Maximum From Array](../removing-minimum-and-maximum-from-array) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let the sum of all points be total_pts. You need to remove a sub-array from cardPoints with length n - k.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep a window of size n - k over the array. The answer is max(answer, total_pts - sumOfCurrentWindow)
-</details>
diff --git a/problems/maximum-population-year/README.md b/problems/maximum-population-year/README.md
deleted file mode 100644
index 5c709dc10..000000000
--- a/problems/maximum-population-year/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-date-format "Convert Date Format")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-distance-between-a-pair-of-values "Maximum Distance Between a Pair of Values")
-
-## [1854. Maximum Population Year (Easy)](https://leetcode.com/problems/maximum-population-year "人口最多的年份")
-
-<p>You are given a 2D integer array <code>logs</code> where each <code>logs[i] = [birth<sub>i</sub>, death<sub>i</sub>]</code> indicates the birth and death years of the <code>i<sup>th</sup></code> person.</p>
-
-<p>The <strong>population</strong> of some year <code>x</code> is the number of people alive during that year. The <code>i<sup>th</sup></code> person is counted in year <code>x</code>&#39;s population if <code>x</code> is in the <strong>inclusive</strong> range <code>[birth<sub>i</sub>, death<sub>i</sub> - 1]</code>. Note that the person is <strong>not</strong> counted in the year that they die.</p>
-
-<p>Return <em>the <strong>earliest</strong> year with the <strong>maximum population</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> logs = [[1993,1999],[2000,2010]]
-<strong>Output:</strong> 1993
-<strong>Explanation:</strong> The maximum population is 1, and 1993 is the earliest year with this population.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> logs = [[1950,1961],[1960,1971],[1970,1981]]
-<strong>Output:</strong> 1960
-<strong>Explanation:</strong> 
-The maximum population is 2, and it had happened in years 1960 and 1970.
-The earlier year between them is 1960.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= logs.length &lt;= 100</code></li>
-	<li><code>1950 &lt;= birth<sub>i</sub> &lt; death<sub>i</sub> &lt;= 2050</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each year find the number of people whose birth_i ≤ year and death_i > year.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the maximum value between all years.
-</details>
diff --git a/problems/maximum-product-difference-between-two-pairs/README.md b/problems/maximum-product-difference-between-two-pairs/README.md
deleted file mode 100644
index c42a5e7f6..000000000
--- a/problems/maximum-product-difference-between-two-pairs/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-movie-rental-system "Design Movie Rental System")
-　　　　　　　　　　　　　　　　
-[Next >](../cyclically-rotating-a-grid "Cyclically Rotating a Grid")
-
-## [1913. Maximum Product Difference Between Two Pairs (Easy)](https://leetcode.com/problems/maximum-product-difference-between-two-pairs "两个数对之间的最大乘积差")
-
-<p>The <strong>product difference</strong> between two pairs <code>(a, b)</code> and <code>(c, d)</code> is defined as <code>(a * b) - (c * d)</code>.</p>
-
-<ul>
-	<li>For example, the product difference between <code>(5, 6)</code> and <code>(2, 7)</code> is <code>(5 * 6) - (2 * 7) = 16</code>.</li>
-</ul>
-
-<p>Given an integer array <code>nums</code>, choose four <strong>distinct</strong> indices <code>w</code>, <code>x</code>, <code>y</code>, and <code>z</code> such that the <strong>product difference</strong> between pairs <code>(nums[w], nums[x])</code> and <code>(nums[y], nums[z])</code> is <strong>maximized</strong>.</p>
-
-<p>Return <em>the <strong>maximum</strong> such product difference</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,6,2,7,4]
-<strong>Output:</strong> 34
-<strong>Explanation:</strong> We can choose indices 1 and 3 for the first pair (6, 7) and indices 2 and 4 for the second pair (2, 4).
-The product difference is (6 * 7) - (2 * 4) = 34.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,5,9,7,4,8]
-<strong>Output:</strong> 64
-<strong>Explanation:</strong> We can choose indices 3 and 6 for the first pair (9, 8) and indices 1 and 5 for the second pair (2, 4).
-The product difference is (9 * 8) - (2 * 4) = 64.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>4 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you only had to find the maximum product of 2 numbers in an array, which 2 numbers should you choose?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We only need to worry about 4 numbers in the array.
-</details>
diff --git a/problems/maximum-product-of-splitted-binary-tree/README.md b/problems/maximum-product-of-splitted-binary-tree/README.md
deleted file mode 100644
index aad097cb2..000000000
--- a/problems/maximum-product-of-splitted-binary-tree/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reduce-array-size-to-the-half "Reduce Array Size to The Half")
-　　　　　　　　　　　　　　　　
-[Next >](../jump-game-v "Jump Game V")
-
-## [1339. Maximum Product of Splitted Binary Tree (Medium)](https://leetcode.com/problems/maximum-product-of-splitted-binary-tree "分裂二叉树的最大乘积")
-
-<p>Given the <code>root</code> of a binary tree, split the binary tree into two subtrees by removing one edge such that the product of the sums of the subtrees is maximized.</p>
-
-<p>Return <em>the maximum product of the sums of the two subtrees</em>. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p><strong>Note</strong> that you need to maximize the answer before taking the mod and not after taking it.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/21/sample_1_1699.png" style="width: 500px; height: 167px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,6]
-<strong>Output:</strong> 110
-<strong>Explanation:</strong> Remove the red edge and get 2 binary trees with sum 11 and 10. Their product is 110 (11*10)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/21/sample_2_1699.png" style="width: 500px; height: 211px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2,3,4,null,null,5,6]
-<strong>Output:</strong> 90
-<strong>Explanation:</strong> Remove the red edge and get 2 binary trees with sum 15 and 6.Their product is 90 (15*6)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[2, 5 * 10<sup>4</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Count Nodes With the Highest Score](../count-nodes-with-the-highest-score) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If we know the sum of a subtree, the answer is max( (total_sum - subtree_sum) * subtree_sum) in each node.
-</details>
diff --git a/problems/maximum-product-of-the-length-of-two-palindromic-subsequences/README.md b/problems/maximum-product-of-the-length-of-two-palindromic-subsequences/README.md
deleted file mode 100644
index e882747e2..000000000
--- a/problems/maximum-product-of-the-length-of-two-palindromic-subsequences/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-pairs-of-interchangeable-rectangles "Number of Pairs of Interchangeable Rectangles")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-missing-genetic-value-in-each-subtree "Smallest Missing Genetic Value in Each Subtree")
-
-## [2002. Maximum Product of the Length of Two Palindromic Subsequences (Medium)](https://leetcode.com/problems/maximum-product-of-the-length-of-two-palindromic-subsequences "两个回文子序列长度的最大乘积")
-
-<p>Given a string <code>s</code>, find two <strong>disjoint palindromic subsequences</strong> of <code>s</code> such that the <strong>product</strong> of their lengths is <strong>maximized</strong>. The two subsequences are <strong>disjoint</strong> if they do not both pick a character at the same index.</p>
-
-<p>Return <em>the <strong>maximum</strong> possible <strong>product</strong> of the lengths of the two palindromic subsequences</em>.</p>
-
-<p>A <strong>subsequence</strong> is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters. A string is <strong>palindromic</strong> if it reads the same forward and backward.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="example-1" src="https://assets.leetcode.com/uploads/2021/08/24/two-palindromic-subsequences.png" style="width: 550px; height: 124px;" />
-<pre>
-<strong>Input:</strong> s = &quot;leetcodecom&quot;
-<strong>Output:</strong> 9
-<strong>Explanation</strong>: An optimal solution is to choose &quot;ete&quot; for the 1<sup>st</sup> subsequence and &quot;cdc&quot; for the 2<sup>nd</sup> subsequence.
-The product of their lengths is: 3 * 3 = 9.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bb&quot;
-<strong>Output:</strong> 1
-<strong>Explanation</strong>: An optimal solution is to choose &quot;b&quot; (the first character) for the 1<sup>st</sup> subsequence and &quot;b&quot; (the second character) for the 2<sup>nd</sup> subsequence.
-The product of their lengths is: 1 * 1 = 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;accbcaxxcxx&quot;
-<strong>Output:</strong> 25
-<strong>Explanation</strong>: An optimal solution is to choose &quot;accca&quot; for the 1<sup>st</sup> subsequence and &quot;xxcxx&quot; for the 2<sup>nd</sup> subsequence.
-The product of their lengths is: 5 * 5 = 25.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 12</code></li>
-	<li><code>s</code> consists of lowercase English letters only.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could you generate all possible pairs of disjoint subsequences?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Could you find the maximum length palindrome in each subsequence for a pair of disjoint subsequences?
-</details>
diff --git a/problems/maximum-product-of-the-length-of-two-palindromic-substrings/README.md b/problems/maximum-product-of-the-length-of-two-palindromic-substrings/README.md
deleted file mode 100644
index 9cdca3f6e..000000000
--- a/problems/maximum-product-of-the-length-of-two-palindromic-substrings/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-total-space-wasted-with-k-resizing-operations "Minimum Total Space Wasted With K Resizing Operations")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-string-is-a-prefix-of-array "Check If String Is a Prefix of Array")
-
-## [1960. Maximum Product of the Length of Two Palindromic Substrings (Hard)](https://leetcode.com/problems/maximum-product-of-the-length-of-two-palindromic-substrings "两个回文子字符串长度的最大乘积")
-
-<p>You are given a <strong>0-indexed</strong> string <code>s</code> and are tasked with finding two <strong>non-intersecting palindromic </strong>substrings of <strong>odd</strong> length such that the product of their lengths is maximized.</p>
-
-<p>More formally, you want to choose four integers <code>i</code>, <code>j</code>, <code>k</code>, <code>l</code> such that <code>0 &lt;= i &lt;= j &lt; k &lt;= l &lt; s.length</code> and both the substrings <code>s[i...j]</code> and <code>s[k...l]</code> are palindromes and have odd lengths. <code>s[i...j]</code> denotes a substring from index <code>i</code> to index <code>j</code> <strong>inclusive</strong>.</p>
-
-<p>Return <em>the <strong>maximum</strong> possible product of the lengths of the two non-intersecting palindromic substrings.</em></p>
-
-<p>A <strong>palindrome</strong> is a string that is the same forward and backward. A <strong>substring</strong> is a contiguous sequence of characters in a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ababbb&quot;
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> Substrings &quot;aba&quot; and &quot;bbb&quot; are palindromes with odd length. product = 3 * 3 = 9.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;zaaaxbbby&quot;
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> Substrings &quot;aaa&quot; and &quot;bbb&quot; are palindromes with odd length. product = 3 * 3 = 9.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can use Manacher's algorithm to get the maximum palindromic substring centered at each index
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After using Manacher's for each center use a line sweep from the center to the left and from the center to the right to find for each index the farthest center to it with distance ≤ palin[center]
-</details>
-
-<details>
-<summary>Hint 3</summary>
-After that, find the maximum palindrome size for each prefix in the string and for each suffix and the answer would be max(prefix[i] * suffix[i + 1])
-</details>
diff --git a/problems/maximum-product-of-three-numbers/README.md b/problems/maximum-product-of-three-numbers/README.md
deleted file mode 100644
index 66da498b6..000000000
--- a/problems/maximum-product-of-three-numbers/README.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../swap-salary "Swap Salary")
-　　　　　　　　　　　　　　　　
-[Next >](../k-inverse-pairs-array "K Inverse Pairs Array")
-
-## [628. Maximum Product of Three Numbers (Easy)](https://leetcode.com/problems/maximum-product-of-three-numbers "三个数的最大乘积")
-
-<p>Given an integer array <code>nums</code>, <em>find three numbers whose product is maximum and return the maximum product</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 6
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> 24
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [-1,-2,-3]
-<strong>Output:</strong> -6
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= nums.length &lt;=&nbsp;10<sup>4</sup></code></li>
-	<li><code>-1000 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Maximum Product Subarray](../maximum-product-subarray) (Medium)
diff --git a/problems/maximum-product-of-three-numbers/maximum_product_of_three_numbers.go b/problems/maximum-product-of-three-numbers/maximum_product_of_three_numbers.go
deleted file mode 100644
index 14445e43d..000000000
--- a/problems/maximum-product-of-three-numbers/maximum_product_of_three_numbers.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem628
-
-import "math"
-
-func maximumProduct(nums []int) int {
-	min1, min2 := math.MaxInt32, math.MaxInt32
-	max1, max2, max3 := math.MinInt32, math.MinInt32, math.MinInt32
-	for _, n := range nums {
-		if n < min1 {
-			min1, min2 = n, min1
-		} else if n < min2 {
-			min2 = n
-		}
-		if n > max3 {
-			max1, max2, max3 = max2, max3, n
-		} else if n > max2 {
-			max1, max2 = max2, n
-		} else if n > max1 {
-			max1 = n
-		}
-	}
-	ans1, ans2 := min1*min2*max3, max1*max2*max3
-	if ans1 > ans2 {
-		return ans1
-	}
-	return ans2
-}
diff --git a/problems/maximum-product-of-three-numbers/maximum_product_of_three_numbers_test.go b/problems/maximum-product-of-three-numbers/maximum_product_of_three_numbers_test.go
deleted file mode 100644
index 546f836ac..000000000
--- a/problems/maximum-product-of-three-numbers/maximum_product_of_three_numbers_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem628
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMaximumProduct(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3},
-			want: 6,
-		},
-		{
-			in:   []int{1, 2, 3, 4},
-			want: 24,
-		},
-		{
-			in:   []int{-2, -1, 0, 2, 3},
-			want: 6,
-		},
-		{
-			in:   []int{-1, -2, -3, 5, 4, 3, 2, 1},
-			want: 60,
-		},
-	}
-	for _, tt := range tests {
-		got := maximumProduct(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/maximum-product-of-two-elements-in-an-array/README.md b/problems/maximum-product-of-two-elements-in-an-array/README.md
deleted file mode 100644
index 6780a411d..000000000
--- a/problems/maximum-product-of-two-elements-in-an-array/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cherry-pickup-ii "Cherry Pickup II")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts "Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts")
-
-## [1464. Maximum Product of Two Elements in an Array (Easy)](https://leetcode.com/problems/maximum-product-of-two-elements-in-an-array "数组中两元素的最大乘积")
-
-Given the array of integers <code>nums</code>, you will choose two different indices <code>i</code> and <code>j</code> of that array. <em>Return the maximum value of</em> <code>(nums[i]-1)*(nums[j]-1)</code>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,4,5,2]
-<strong>Output:</strong> 12 
-<strong>Explanation:</strong> If you choose the indices i=1 and j=2 (indexed from 0), you will get the maximum value, that is, (nums[1]-1)*(nums[2]-1) = (4-1)*(5-1) = 3*4 = 12. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5,4,5]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> Choosing the indices i=1 and j=3 (indexed from 0), you will get the maximum value of (5-1)*(5-1) = 16.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,7]
-<strong>Output:</strong> 12
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 500</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10^3</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use brute force: two loops to select i and j, then select the maximum value of (nums[i]-1)*(nums[j]-1).
-</details>
diff --git a/problems/maximum-product-of-word-lengths/README.md b/problems/maximum-product-of-word-lengths/README.md
deleted file mode 100644
index 40fec0598..000000000
--- a/problems/maximum-product-of-word-lengths/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-distance-from-all-buildings "Shortest Distance from All Buildings")
-　　　　　　　　　　　　　　　　
-[Next >](../bulb-switcher "Bulb Switcher")
-
-## [318. Maximum Product of Word Lengths (Medium)](https://leetcode.com/problems/maximum-product-of-word-lengths "最大单词长度乘积")
-
-<p>Given a string array <code>words</code>, return <em>the maximum value of</em> <code>length(word[i]) * length(word[j])</code> <em>where the two words do not share common letters</em>. If no such two words exist, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;abcw&quot;,&quot;baz&quot;,&quot;foo&quot;,&quot;bar&quot;,&quot;xtfn&quot;,&quot;abcdef&quot;]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> The two words can be &quot;abcw&quot;, &quot;xtfn&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;a&quot;,&quot;ab&quot;,&quot;abc&quot;,&quot;d&quot;,&quot;cd&quot;,&quot;bcd&quot;,&quot;abcd&quot;]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The two words can be &quot;ab&quot;, &quot;cd&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;a&quot;,&quot;aa&quot;,&quot;aaa&quot;,&quot;aaaa&quot;]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> No such pair of words.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= words.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 1000</code></li>
-	<li><code>words[i]</code> consists only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/maximum-product-of-word-lengths/maximum_product_of_word_lengths.go b/problems/maximum-product-of-word-lengths/maximum_product_of_word_lengths.go
deleted file mode 100644
index d1cf4a589..000000000
--- a/problems/maximum-product-of-word-lengths/maximum_product_of_word_lengths.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem318
diff --git a/problems/maximum-product-of-word-lengths/maximum_product_of_word_lengths_test.go b/problems/maximum-product-of-word-lengths/maximum_product_of_word_lengths_test.go
deleted file mode 100644
index d1cf4a589..000000000
--- a/problems/maximum-product-of-word-lengths/maximum_product_of_word_lengths_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem318
diff --git a/problems/maximum-product-subarray/README.md b/problems/maximum-product-subarray/README.md
deleted file mode 100644
index e404b0797..000000000
--- a/problems/maximum-product-subarray/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-words-in-a-string "Reverse Words in a String")
-　　　　　　　　　　　　　　　　
-[Next >](../find-minimum-in-rotated-sorted-array "Find Minimum in Rotated Sorted Array")
-
-## [152. Maximum Product Subarray (Medium)](https://leetcode.com/problems/maximum-product-subarray "乘积最大子数组")
-
-<p>Given an integer array <code>nums</code>, find a contiguous non-empty subarray within the array that has the largest product, and return <em>the product</em>.</p>
-
-<p>It is <strong>guaranteed</strong> that the answer will fit in a <strong>32-bit</strong> integer.</p>
-
-<p>A <strong>subarray</strong> is a contiguous subsequence of the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,-2,4]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> [2,3] has the largest product 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-2,0,-1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The result cannot be 2, because [-2,-1] is not a subarray.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>-10 &lt;= nums[i] &lt;= 10</code></li>
-	<li>The product of any prefix or suffix of <code>nums</code> is <strong>guaranteed</strong> to fit in a <strong>32-bit</strong> integer.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Maximum Subarray](../maximum-subarray) (Easy)
-  1. [House Robber](../house-robber) (Medium)
-  1. [Product of Array Except Self](../product-of-array-except-self) (Medium)
-  1. [Maximum Product of Three Numbers](../maximum-product-of-three-numbers) (Easy)
-  1. [Subarray Product Less Than K](../subarray-product-less-than-k) (Medium)
diff --git a/problems/maximum-product-subarray/maximum_product_subarray.go b/problems/maximum-product-subarray/maximum_product_subarray.go
deleted file mode 100644
index 5544f1d4c..000000000
--- a/problems/maximum-product-subarray/maximum_product_subarray.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem152
diff --git a/problems/maximum-product-subarray/maximum_product_subarray_test.go b/problems/maximum-product-subarray/maximum_product_subarray_test.go
deleted file mode 100644
index 5544f1d4c..000000000
--- a/problems/maximum-product-subarray/maximum_product_subarray_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem152
diff --git a/problems/maximum-profit-in-job-scheduling/README.md b/problems/maximum-profit-in-job-scheduling/README.md
deleted file mode 100644
index 8cb51b614..000000000
--- a/problems/maximum-profit-in-job-scheduling/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../replace-the-substring-for-balanced-string "Replace the Substring for Balanced String")
-　　　　　　　　　　　　　　　　
-[Next >](../web-crawler "Web Crawler")
-
-## [1235. Maximum Profit in Job Scheduling (Hard)](https://leetcode.com/problems/maximum-profit-in-job-scheduling "规划兼职工作")
-
-<p>We have <code>n</code> jobs, where every job is scheduled to be done from <code>startTime[i]</code> to <code>endTime[i]</code>, obtaining a profit of <code>profit[i]</code>.</p>
-
-<p>You&#39;re given the <code>startTime</code>, <code>endTime</code> and <code>profit</code> arrays, return the maximum profit you can take such that there are no two jobs in the subset with overlapping time range.</p>
-
-<p>If you choose a job that ends at time <code>X</code> you will be able to start another job that starts at time <code>X</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/10/10/sample1_1584.png" style="width: 380px; height: 154px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> startTime = [1,2,3,3], endTime = [3,4,5,6], profit = [50,10,40,70]
-<strong>Output:</strong> 120
-<strong>Explanation:</strong> The subset chosen is the first and fourth job. 
-Time range [1-3]+[3-6] , we get profit of 120 = 50 + 70.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/10/10/sample22_1584.png" style="width: 600px; height: 112px;" /> </strong></p>
-
-<pre>
-<strong>Input:</strong> startTime = [1,2,3,4,6], endTime = [3,5,10,6,9], profit = [20,20,100,70,60]
-<strong>Output:</strong> 150
-<strong>Explanation:</strong> The subset chosen is the first, fourth and fifth job. 
-Profit obtained 150 = 20 + 70 + 60.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/10/10/sample3_1584.png" style="width: 400px; height: 112px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> startTime = [1,1,1], endTime = [2,3,4], profit = [5,6,4]
-<strong>Output:</strong> 6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= startTime.length == endTime.length == profit.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= startTime[i] &lt; endTime[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= profit[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think on DP.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort the elements by starting time, then define the dp[i] as the maximum profit taking elements from the suffix starting at i.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use binarySearch (lower_bound/upper_bound on C++) to get the next index for the DP transition.
-</details>
diff --git a/problems/maximum-profit-of-operating-a-centennial-wheel/README.md b/problems/maximum-profit-of-operating-a-centennial-wheel/README.md
deleted file mode 100644
index 0ef854aa3..000000000
--- a/problems/maximum-profit-of-operating-a-centennial-wheel/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../crawler-log-folder "Crawler Log Folder")
-　　　　　　　　　　　　　　　　
-[Next >](../throne-inheritance "Throne Inheritance")
-
-## [1599. Maximum Profit of Operating a Centennial Wheel (Medium)](https://leetcode.com/problems/maximum-profit-of-operating-a-centennial-wheel "经营摩天轮的最大利润")
-
-<p>You are the operator of a Centennial Wheel that has <strong>four gondolas</strong>, and each gondola has room for <strong>up</strong> <strong>to</strong> <strong>four people</strong>. You have the ability to rotate the gondolas <strong>counterclockwise</strong>, which costs you <code>runningCost</code> dollars.</p>
-
-<p>You are given an array <code>customers</code> of length <code>n</code> where <code>customers[i]</code> is the number of new customers arriving just before the <code>i<sup>th</sup></code> rotation (0-indexed). This means you <strong>must rotate the wheel </strong><code>i</code><strong> times before the </strong><code>customers[i]</code><strong> customers arrive</strong>. <strong>You cannot make customers wait if there is room in the gondola</strong>. Each customer pays <code>boardingCost</code> dollars when they board on the gondola closest to the ground and will exit once that gondola reaches the ground again.</p>
-
-<p>You can stop the wheel at any time, including <strong>before</strong> <strong>serving</strong> <strong>all</strong> <strong>customers</strong>. If you decide to stop serving customers, <strong>all subsequent rotations are free</strong> in order to get all the customers down safely. Note that if there are currently more than four customers waiting at the wheel, only four will board the gondola, and the rest will wait <strong>for the next rotation</strong>.</p>
-
-<p>Return<em> the minimum number of rotations you need to perform to maximize your profit.</em> If there is <strong>no scenario</strong> where the profit is positive, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/09/wheeldiagram12.png" style="width: 700px; height: 225px;" />
-<pre>
-<strong>Input:</strong> customers = [8,3], boardingCost = 5, runningCost = 6
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The numbers written on the gondolas are the number of people currently there.
-1. 8 customers arrive, 4 board and 4 wait for the next gondola, the wheel rotates. Current profit is 4 * $5 - 1 * $6 = $14.
-2. 3 customers arrive, the 4 waiting board the wheel and the other 3 wait, the wheel rotates. Current profit is 8 * $5 - 2 * $6 = $28.
-3. The final 3 customers board the gondola, the wheel rotates. Current profit is 11 * $5 - 3 * $6 = $37.
-The highest profit was $37 after rotating the wheel 3 times.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> customers = [10,9,6], boardingCost = 6, runningCost = 4
-<strong>Output:</strong> 7
-<strong>Explanation:</strong>
-1. 10 customers arrive, 4 board and 6 wait for the next gondola, the wheel rotates. Current profit is 4 * $6 - 1 * $4 = $20.
-2. 9 customers arrive, 4 board and 11 wait (2 originally waiting, 9 newly waiting), the wheel rotates. Current profit is 8 * $6 - 2 * $4 = $40.
-3. The final 6 customers arrive, 4 board and 13 wait, the wheel rotates. Current profit is 12 * $6 - 3 * $4 = $60.
-4. 4 board and 9 wait, the wheel rotates. Current profit is 16 * $6 - 4 * $4 = $80.
-5. 4 board and 5 wait, the wheel rotates. Current profit is 20 * $6 - 5 * $4 = $100.
-6. 4 board and 1 waits, the wheel rotates. Current profit is 24 * $6 - 6 * $4 = $120.
-7. 1 boards, the wheel rotates. Current profit is 25 * $6 - 7 * $4 = $122.
-The highest profit was $122 after rotating the wheel 7 times.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> customers = [3,4,0,5,1], boardingCost = 1, runningCost = 92
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>
-1. 3 customers arrive, 3 board and 0 wait, the wheel rotates. Current profit is 3 * $1 - 1 * $92 = -$89.
-2. 4 customers arrive, 4 board and 0 wait, the wheel rotates. Current profit is 7 * $1 - 2 * $92 = -$177.
-3. 0 customers arrive, 0 board and 0 wait, the wheel rotates. Current profit is 7 * $1 - 3 * $92 = -$269.
-4. 5 customers arrive, 4 board and 1 waits, the wheel rotates. Current profit is 11 * $1 - 4 * $92 = -$357.
-5. 1 customer arrives, 2 board and 0 wait, the wheel rotates. Current profit is 13 * $1 - 5 * $92 = -$447.
-The profit was never positive, so return -1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == customers.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= customers[i] &lt;= 50</code></li>
-	<li><code>1 &lt;= boardingCost, runningCost &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think simulation
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Note that the number of turns will never be more than 50 / 4 * n
-</details>
diff --git a/problems/maximum-repeating-substring/README.md b/problems/maximum-repeating-substring/README.md
deleted file mode 100644
index 708d69560..000000000
--- a/problems/maximum-repeating-substring/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fix-names-in-a-table "Fix Names in a Table")
-　　　　　　　　　　　　　　　　
-[Next >](../merge-in-between-linked-lists "Merge In Between Linked Lists")
-
-## [1668. Maximum Repeating Substring (Easy)](https://leetcode.com/problems/maximum-repeating-substring "最大重复子字符串")
-
-<p>For a string <code>sequence</code>, a string <code>word</code> is <strong><code>k</code>-repeating</strong> if <code>word</code> concatenated <code>k</code> times is a substring of <code>sequence</code>. The <code>word</code>&#39;s <strong>maximum <code>k</code>-repeating value</strong> is the highest value <code>k</code> where <code>word</code> is <code>k</code>-repeating in <code>sequence</code>. If <code>word</code> is not a substring of <code>sequence</code>, <code>word</code>&#39;s maximum <code>k</code>-repeating value is <code>0</code>.</p>
-
-<p>Given strings <code>sequence</code> and <code>word</code>, return <em>the <strong>maximum <code>k</code>-repeating value</strong> of <code>word</code> in <code>sequence</code></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> sequence = &quot;ababc&quot;, word = &quot;ab&quot;
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>&quot;abab&quot; is a substring in &quot;<u>abab</u>c&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> sequence = &quot;ababc&quot;, word = &quot;ba&quot;
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>&quot;ba&quot; is a substring in &quot;a<u>ba</u>bc&quot;. &quot;baba&quot; is not a substring in &quot;ababc&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> sequence = &quot;ababc&quot;, word = &quot;ac&quot;
-<strong>Output:</strong> 0
-<strong>Explanation: </strong>&quot;ac&quot; is not a substring in &quot;ababc&quot;. 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= sequence.length &lt;= 100</code></li>
-	<li><code>1 &lt;= word.length &lt;= 100</code></li>
-	<li><code>sequence</code> and <code>word</code>&nbsp;contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The constraints are low enough for a brute force approach.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try every k value from 0 upwards until word is no longer k-repeating.
-</details>
diff --git a/problems/maximum-running-time-of-n-computers/README.md b/problems/maximum-running-time-of-n-computers/README.md
deleted file mode 100644
index 671f8e340..000000000
--- a/problems/maximum-running-time-of-n-computers/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../solving-questions-with-brainpower "Solving Questions With Brainpower")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-passengers-in-each-bus-i "The Number of Passengers in Each Bus I")
-
-## [2141. Maximum Running Time of N Computers (Hard)](https://leetcode.com/problems/maximum-running-time-of-n-computers "同时运行 N 台电脑的最长时间")
-
-<p>You have <code>n</code> computers. You are given the integer <code>n</code> and a <strong>0-indexed</strong> integer array <code>batteries</code> where the <code>i<sup>th</sup></code> battery can <strong>run</strong> a computer for <code>batteries[i]</code> minutes. You are interested in running <strong>all</strong> <code>n</code> computers <strong>simultaneously</strong> using the given batteries.</p>
-
-<p>Initially, you can insert <strong>at most one battery</strong> into each computer. After that and at any integer time moment, you can remove a battery from a computer and insert another battery <strong>any number of times</strong>. The inserted battery can be a totally new battery or a battery from another computer. You may assume that the removing and inserting processes take no time.</p>
-
-<p>Note that the batteries cannot be recharged.</p>
-
-<p>Return <em>the <strong>maximum</strong> number of minutes you can run all the </em><code>n</code><em> computers simultaneously.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2022/01/06/example1-fit.png" style="width: 762px; height: 150px;" />
-<pre>
-<strong>Input:</strong> n = 2, batteries = [3,3,3]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> 
-Initially, insert battery 0 into the first computer and battery 1 into the second computer.
-After two minutes, remove battery 1 from the second computer and insert battery 2 instead. Note that battery 1 can still run for one minute.
-At the end of the third minute, battery 0 is drained, and you need to remove it from the first computer and insert battery 1 instead.
-By the end of the fourth minute, battery 1 is also drained, and the first computer is no longer running.
-We can run the two computers simultaneously for at most 4 minutes, so we return 4.
-
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2022/01/06/example2.png" style="width: 629px; height: 150px;" />
-<pre>
-<strong>Input:</strong> n = 2, batteries = [1,1,1,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-Initially, insert battery 0 into the first computer and battery 2 into the second computer. 
-After one minute, battery 0 and battery 2 are drained so you need to remove them and insert battery 1 into the first computer and battery 3 into the second computer. 
-After another minute, battery 1 and battery 3 are also drained so the first and second computers are no longer running.
-We can run the two computers simultaneously for at most 2 minutes, so we return 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= batteries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= batteries[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For a given running time, can you determine if it is possible to run all n computers simultaneously?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to use Binary Search to find the maximal running time
-</details>
diff --git a/problems/maximum-score-after-splitting-a-string/README.md b/problems/maximum-score-after-splitting-a-string/README.md
deleted file mode 100644
index 589727c3a..000000000
--- a/problems/maximum-score-after-splitting-a-string/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../npv-queries "NPV Queries")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-points-you-can-obtain-from-cards "Maximum Points You Can Obtain from Cards")
-
-## [1422. Maximum Score After Splitting a String (Easy)](https://leetcode.com/problems/maximum-score-after-splitting-a-string "分割字符串的最大得分")
-
-<p>Given a&nbsp;string <code>s</code>&nbsp;of zeros and ones, <em>return the maximum score after splitting the string into two <strong>non-empty</strong> substrings</em> (i.e. <strong>left</strong> substring and <strong>right</strong> substring).</p>
-
-<p>The score after splitting a string is the number of <strong>zeros</strong> in the <strong>left</strong> substring plus the number of <strong>ones</strong> in the <strong>right</strong> substring.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;011101&quot;
-<strong>Output:</strong> 5 
-<strong>Explanation:</strong> 
-All possible ways of splitting s into two non-empty substrings are:
-left = &quot;0&quot; and right = &quot;11101&quot;, score = 1 + 4 = 5 
-left = &quot;01&quot; and right = &quot;1101&quot;, score = 1 + 3 = 4 
-left = &quot;011&quot; and right = &quot;101&quot;, score = 1 + 2 = 3 
-left = &quot;0111&quot; and right = &quot;01&quot;, score = 1 + 1 = 2 
-left = &quot;01110&quot; and right = &quot;1&quot;, score = 2 + 1 = 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;00111&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> When left = &quot;00&quot; and right = &quot;111&quot;, we get the maximum score = 2 + 3 = 5
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1111&quot;
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 500</code></li>
-	<li>The string <code>s</code> consists of characters <code>&#39;0&#39;</code> and <code>&#39;1&#39;</code> only.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Precompute a prefix sum of ones ('1').
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Iterate from left to right counting the number of zeros ('0'), then use the precomputed prefix sum for counting ones ('1'). Update the answer.
-</details>
diff --git a/problems/maximum-score-after-splitting-a-string/maximum_score_after_splitting_a_string.go b/problems/maximum-score-after-splitting-a-string/maximum_score_after_splitting_a_string.go
deleted file mode 100644
index d889bf61f..000000000
--- a/problems/maximum-score-after-splitting-a-string/maximum_score_after_splitting_a_string.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem1422
-
-import "strings"
-
-func maxScore(s string) int {
-	ans := 0
-	n0 := 0
-	n1 := strings.Count(s, "1")
-	for _, v := range s[:len(s)-1] {
-		if v == '1' {
-			n1--
-		} else {
-			n0++
-		}
-		if ans < n0+n1 {
-			ans = n0 + n1
-		}
-	}
-	return ans
-}
diff --git a/problems/maximum-score-after-splitting-a-string/maximum_score_after_splitting_a_string_test.go b/problems/maximum-score-after-splitting-a-string/maximum_score_after_splitting_a_string_test.go
deleted file mode 100644
index 87dddd3da..000000000
--- a/problems/maximum-score-after-splitting-a-string/maximum_score_after_splitting_a_string_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1422
-
-import "testing"
-
-type testType struct {
-	in   string
-	want int
-}
-
-func TestMaxScore(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "011101",
-			want: 5,
-		},
-		{
-			in:   "00111",
-			want: 5,
-		},
-		{
-			in:   "1111",
-			want: 3,
-		},
-		{
-			in:   "000000",
-			want: 5,
-		},
-	}
-	for _, tt := range tests {
-		got := maxScore(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/maximum-score-from-performing-multiplication-operations/README.md b/problems/maximum-score-from-performing-multiplication-operations/README.md
deleted file mode 100644
index 31175d357..000000000
--- a/problems/maximum-score-from-performing-multiplication-operations/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-operations-to-move-all-balls-to-each-box "Minimum Number of Operations to Move All Balls to Each Box")
-　　　　　　　　　　　　　　　　
-[Next >](../maximize-palindrome-length-from-subsequences "Maximize Palindrome Length From Subsequences")
-
-## [1770. Maximum Score from Performing Multiplication Operations (Medium)](https://leetcode.com/problems/maximum-score-from-performing-multiplication-operations "执行乘法运算的最大分数")
-
-<p>You are given two integer arrays <code>nums</code> and <code>multipliers</code><strong> </strong>of size <code>n</code> and <code>m</code> respectively, where <code>n &gt;= m</code>. The arrays are <strong>1-indexed</strong>.</p>
-
-<p>You begin with a score of <code>0</code>. You want to perform <strong>exactly</strong> <code>m</code> operations. On the <code>i<sup>th</sup></code> operation <strong>(1-indexed)</strong>, you will:</p>
-
-<ul>
-	<li>Choose one integer <code>x</code> from <strong>either the start or the end </strong>of the array <code>nums</code>.</li>
-	<li>Add <code>multipliers[i] * x</code> to your score.</li>
-	<li>Remove <code>x</code> from the array <code>nums</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>maximum</strong> score after performing </em><code>m</code> <em>operations.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3], multipliers = [3,2,1]
-<strong>Output:</strong> 14
-<strong>Explanation:</strong>&nbsp;An optimal solution is as follows:
-- Choose from the end, [1,2,<strong><u>3</u></strong>], adding 3 * 3 = 9 to the score.
-- Choose from the end, [1,<strong><u>2</u></strong>], adding 2 * 2 = 4 to the score.
-- Choose from the end, [<strong><u>1</u></strong>], adding 1 * 1 = 1 to the score.
-The total score is 9 + 4 + 1 = 14.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-5,-3,-3,-2,7,1], multipliers = [-10,-5,3,4,6]
-<strong>Output:</strong> 102
-<strong>Explanation: </strong>An optimal solution is as follows:
-- Choose from the start, [<u><strong>-5</strong></u>,-3,-3,-2,7,1], adding -5 * -10 = 50 to the score.
-- Choose from the start, [<strong><u>-3</u></strong>,-3,-2,7,1], adding -3 * -5 = 15 to the score.
-- Choose from the start, [<strong><u>-3</u></strong>,-2,7,1], adding -3 * 3 = -9 to the score.
-- Choose from the end, [-2,7,<strong><u>1</u></strong>], adding 1 * 4 = 4 to the score.
-- Choose from the end, [-2,<strong><u>7</u></strong>], adding 7 * 6 = 42 to the score. 
-The total score is 50 + 15 - 9 + 4 + 42 = 102.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>m == multipliers.length</code></li>
-	<li><code>1 &lt;= m &lt;= 10<sup>3</sup></code></li>
-	<li><code>m &lt;= n &lt;= 10<sup>5</sup></code><code> </code></li>
-	<li><code>-1000 &lt;= nums[i], multipliers[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Maximum Points You Can Obtain from Cards](../maximum-points-you-can-obtain-from-cards) (Medium)
-  1. [Stone Game VII](../stone-game-vii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-At first glance, the solution seems to be greedy, but if you try to greedily take the largest value from the beginning or the end, this will not be optimal.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You should try all scenarios but this will be costy.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Memoizing the pre-visited states while trying all the possible scenarios will reduce the complexity, and hence dp is a perfect choice here.
-</details>
diff --git a/problems/maximum-score-from-removing-stones/README.md b/problems/maximum-score-from-removing-stones/README.md
deleted file mode 100644
index 01389e015..000000000
--- a/problems/maximum-score-from-removing-stones/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-array-is-sorted-and-rotated "Check if Array Is Sorted and Rotated")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-merge-of-two-strings "Largest Merge Of Two Strings")
-
-## [1753. Maximum Score From Removing Stones (Medium)](https://leetcode.com/problems/maximum-score-from-removing-stones "移除石子的最大得分")
-
-<p>You are playing a solitaire game with <strong>three piles</strong> of stones of sizes <code>a</code>​​​​​​, <code>b</code>,​​​​​​ and <code>c</code>​​​​​​ respectively. Each turn you choose two <strong>different non-empty </strong>piles, take one stone from each, and add <code>1</code> point to your score. The game stops when there are <strong>fewer than two non-empty</strong> piles (meaning there are no more available moves).</p>
-
-<p>Given three integers <code>a</code>​​​​​, <code>b</code>,​​​​​ and <code>c</code>​​​​​, return <em>the</em> <strong><em>maximum</em> </strong><em><strong>score</strong> you can get.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 2, b = 4, c = 6
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The starting state is (2, 4, 6). One optimal set of moves is:
-- Take from 1st and 3rd piles, state is now (1, 4, 5)
-- Take from 1st and 3rd piles, state is now (0, 4, 4)
-- Take from 2nd and 3rd piles, state is now (0, 3, 3)
-- Take from 2nd and 3rd piles, state is now (0, 2, 2)
-- Take from 2nd and 3rd piles, state is now (0, 1, 1)
-- Take from 2nd and 3rd piles, state is now (0, 0, 0)
-There are fewer than two non-empty piles, so the game ends. Total: 6 points.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 4, b = 4, c = 6
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The starting state is (4, 4, 6). One optimal set of moves is:
-- Take from 1st and 2nd piles, state is now (3, 3, 6)
-- Take from 1st and 3rd piles, state is now (2, 3, 5)
-- Take from 1st and 3rd piles, state is now (1, 3, 4)
-- Take from 1st and 3rd piles, state is now (0, 3, 3)
-- Take from 2nd and 3rd piles, state is now (0, 2, 2)
-- Take from 2nd and 3rd piles, state is now (0, 1, 1)
-- Take from 2nd and 3rd piles, state is now (0, 0, 0)
-There are fewer than two non-empty piles, so the game ends. Total: 7 points.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 1, b = 8, c = 8
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> One optimal set of moves is to take from the 2nd and 3rd piles for 8 turns until they are empty.
-After that, there are fewer than two non-empty piles, so the game ends.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= a, b, c &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-It's optimal to always remove one stone from the biggest 2 piles
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Note that the limits are small enough for simulation
-</details>
diff --git a/problems/maximum-score-from-removing-substrings/README.md b/problems/maximum-score-from-removing-substrings/README.md
deleted file mode 100644
index 7fca866cd..000000000
--- a/problems/maximum-score-from-removing-substrings/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../calculate-money-in-leetcode-bank "Calculate Money in Leetcode Bank")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-the-lexicographically-largest-valid-sequence "Construct the Lexicographically Largest Valid Sequence")
-
-## [1717. Maximum Score From Removing Substrings (Medium)](https://leetcode.com/problems/maximum-score-from-removing-substrings "删除子字符串的最大得分")
-
-<p>You are given a string <code>s</code> and two integers <code>x</code> and <code>y</code>. You can perform two types of operations any number of times.</p>
-
-<ul>
-	<li>Remove substring <code>&quot;ab&quot;</code> and gain <code>x</code> points.
-	<ul>
-		<li>For example, when removing <code>&quot;ab&quot;</code> from <code>&quot;c<u>ab</u>xbae&quot;</code> it becomes <code>&quot;cxbae&quot;</code>.</li>
-	</ul>
-	</li>
-	<li>Remove substring <code>&quot;ba&quot;</code> and gain <code>y</code> points.
-	<ul>
-		<li>For example, when removing <code>&quot;ba&quot;</code> from <code>&quot;cabx<u>ba</u>e&quot;</code> it becomes <code>&quot;cabxe&quot;</code>.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <em>the maximum points you can gain after applying the above operations on</em> <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cdbcbbaaabab&quot;, x = 4, y = 5
-<strong>Output:</strong> 19
-<strong>Explanation:</strong>
-- Remove the &quot;ba&quot; underlined in &quot;cdbcbbaaa<u>ba</u>b&quot;. Now, s = &quot;cdbcbbaaab&quot; and 5 points are added to the score.
-- Remove the &quot;ab&quot; underlined in &quot;cdbcbbaa<u>ab</u>&quot;. Now, s = &quot;cdbcbbaa&quot; and 4 points are added to the score.
-- Remove the &quot;ba&quot; underlined in &quot;cdbcb<u>ba</u>a&quot;. Now, s = &quot;cdbcba&quot; and 5 points are added to the score.
-- Remove the &quot;ba&quot; underlined in &quot;cdbc<u>ba</u>&quot;. Now, s = &quot;cdbc&quot; and 5 points are added to the score.
-Total score = 5 + 4 + 5 + 5 = 19.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabbaaxybbaabb&quot;, x = 5, y = 4
-<strong>Output:</strong> 20
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= x, y &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Count Words Obtained After Adding a Letter](../count-words-obtained-after-adding-a-letter) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that it is always more optimal to take one type of substring before another
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can use a stack to handle erasures
-</details>
diff --git a/problems/maximum-score-of-a-good-subarray/README.md b/problems/maximum-score-of-a-good-subarray/README.md
deleted file mode 100644
index 46c3d4d84..000000000
--- a/problems/maximum-score-of-a-good-subarray/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-average-pass-ratio "Maximum Average Pass Ratio")
-　　　　　　　　　　　　　　　　
-[Next >](../count-pairs-of-equal-substrings-with-minimum-difference "Count Pairs of Equal Substrings With Minimum Difference")
-
-## [1793. Maximum Score of a Good Subarray (Hard)](https://leetcode.com/problems/maximum-score-of-a-good-subarray "好子数组的最大分数")
-
-<p>You are given an array of integers <code>nums</code> <strong>(0-indexed)</strong> and an integer <code>k</code>.</p>
-
-<p>The <strong>score</strong> of a subarray <code>(i, j)</code> is defined as <code>min(nums[i], nums[i+1], ..., nums[j]) * (j - i + 1)</code>. A <strong>good</strong> subarray is a subarray where <code>i &lt;= k &lt;= j</code>.</p>
-
-<p>Return <em>the maximum possible <strong>score</strong> of a <strong>good</strong> subarray.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,4,3,7,4,5], k = 3
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> The optimal subarray is (1, 5) with a score of min(4,3,7,4,5) * (5-1+1) = 3 * 5 = 15. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,5,4,5,4,1,1,1], k = 0
-<strong>Output:</strong> 20
-<strong>Explanation:</strong> The optimal subarray is (0, 4) with a score of min(5,5,4,5,4) * (4-0+1) = 4 * 5 = 20.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= k &lt; nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Largest Rectangle in Histogram](../largest-rectangle-in-histogram) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try thinking about the prefix before index k and the suffix after index k as two separate arrays.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Using two pointers or binary search, we can find the maximum prefix of each array where the numbers are less than or equal to a certain value
-</details>
diff --git a/problems/maximum-score-words-formed-by-letters/README.md b/problems/maximum-score-words-formed-by-letters/README.md
deleted file mode 100644
index f2d0288bb..000000000
--- a/problems/maximum-score-words-formed-by-letters/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-closed-islands "Number of Closed Islands")
-　　　　　　　　　　　　　　　　
-[Next >](../encode-number "Encode Number")
-
-## [1255. Maximum Score Words Formed by Letters (Hard)](https://leetcode.com/problems/maximum-score-words-formed-by-letters "得分最高的单词集合")
-
-<p>Given a list of <code>words</code>, list of&nbsp; single&nbsp;<code>letters</code> (might be repeating)&nbsp;and <code>score</code>&nbsp;of every character.</p>
-
-<p>Return the maximum score of <strong>any</strong> valid set of words formed by using the given letters (<code>words[i]</code> cannot be used two&nbsp;or more times).</p>
-
-<p>It is not necessary to use all characters in <code>letters</code> and each letter can only be used once. Score of letters&nbsp;<code>&#39;a&#39;</code>, <code>&#39;b&#39;</code>, <code>&#39;c&#39;</code>, ... ,<code>&#39;z&#39;</code> is given by&nbsp;<code>score[0]</code>, <code>score[1]</code>, ... , <code>score[25]</code> respectively.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;dog&quot;,&quot;cat&quot;,&quot;dad&quot;,&quot;good&quot;], letters = [&quot;a&quot;,&quot;a&quot;,&quot;c&quot;,&quot;d&quot;,&quot;d&quot;,&quot;d&quot;,&quot;g&quot;,&quot;o&quot;,&quot;o&quot;], score = [1,0,9,5,0,0,3,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0]
-<strong>Output:</strong> 23
-<strong>Explanation:</strong>
-Score  a=1, c=9, d=5, g=3, o=2
-Given letters, we can form the words &quot;dad&quot; (5+1+5) and &quot;good&quot; (3+2+2+5) with a score of 23.
-Words &quot;dad&quot; and &quot;dog&quot; only get a score of 21.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;xxxz&quot;,&quot;ax&quot;,&quot;bx&quot;,&quot;cx&quot;], letters = [&quot;z&quot;,&quot;a&quot;,&quot;b&quot;,&quot;c&quot;,&quot;x&quot;,&quot;x&quot;,&quot;x&quot;], score = [4,4,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,5,0,10]
-<strong>Output:</strong> 27
-<strong>Explanation:</strong>
-Score  a=4, b=4, c=4, x=5, z=10
-Given letters, we can form the words &quot;ax&quot; (4+5), &quot;bx&quot; (4+5) and &quot;cx&quot; (4+5) with a score of 27.
-Word &quot;xxxz&quot; only get a score of 25.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;leetcode&quot;], letters = [&quot;l&quot;,&quot;e&quot;,&quot;t&quot;,&quot;c&quot;,&quot;o&quot;,&quot;d&quot;], score = [0,0,1,1,1,0,0,0,0,0,0,1,0,0,1,0,0,0,0,1,0,0,0,0,0,0]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-Letter &quot;e&quot; can only be used once.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 14</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 15</code></li>
-	<li><code>1 &lt;= letters.length &lt;= 100</code></li>
-	<li><code>letters[i].length == 1</code></li>
-	<li><code>score.length ==&nbsp;26</code></li>
-	<li><code>0 &lt;= score[i] &lt;= 10</code></li>
-	<li><code>words[i]</code>, <code>letters[i]</code>&nbsp;contains only lower case English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Similar Questions
-  1. [Maximum Good People Based on Statements](../maximum-good-people-based-on-statements) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that words.length is small. This means you can iterate over every subset of words (2^N).
-</details>
diff --git a/problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold/README.md b/problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold/README.md
deleted file mode 100644
index 96e80a8cc..000000000
--- a/problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sequential-digits "Sequential Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-path-in-a-grid-with-obstacles-elimination "Shortest Path in a Grid with Obstacles Elimination")
-
-## [1292. Maximum Side Length of a Square with Sum Less than or Equal to Threshold (Medium)](https://leetcode.com/problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold "元素和小于等于阈值的正方形的最大边长")
-
-<p>Given a <code>m x n</code>&nbsp;matrix <code>mat</code> and an integer <code>threshold</code>. Return the maximum side-length of a square with a sum less than or equal to <code>threshold</code> or return <strong>0</strong> if there is no such square.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/12/05/e1.png" style="width: 335px; height: 186px;" />
-<pre>
-<strong>Input:</strong> mat = [[1,1,3,2,4,3,2],[1,1,3,2,4,3,2],[1,1,3,2,4,3,2]], threshold = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The maximum side length of square with sum less than 4 is 2 as shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[2,2,2,2,2],[2,2,2,2,2],[2,2,2,2,2],[2,2,2,2,2],[2,2,2,2,2]], threshold = 1
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[1,1,1,1],[1,0,0,0],[1,0,0,0],[1,0,0,0]], threshold = 6
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[18,70],[61,1],[25,85],[14,40],[11,96],[97,96],[63,45]], threshold = 40184
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m, n &lt;= 300</code></li>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>0 &lt;= mat[i][j] &lt;= 10000</code></li>
-	<li><code>0 &lt;= threshold&nbsp;&lt;= 10^5</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Store prefix sum of all grids in another 2D array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try all possible solutions and if you cannot find one return -1.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If x is a valid answer then any y < x is also valid answer. Use binary search to find answer.
-</details>
diff --git a/problems/maximum-size-subarray-sum-equals-k/README.md b/problems/maximum-size-subarray-sum-equals-k/README.md
deleted file mode 100644
index 0a84dae57..000000000
--- a/problems/maximum-size-subarray-sum-equals-k/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../wiggle-sort-ii "Wiggle Sort II")
-　　　　　　　　　　　　　　　　
-[Next >](../power-of-three "Power of Three")
-
-## [325. Maximum Size Subarray Sum Equals k (Medium)](https://leetcode.com/problems/maximum-size-subarray-sum-equals-k "和等于 k 的最长子数组长度")
-
-<p>Given an array <i>nums</i> and a target value <i>k</i>, find the maximum length of a subarray that sums to <i>k</i>. If there isn&#39;t one, return 0 instead.</p>
-
-<p><b>Note:</b><br />
-The sum of the entire <i>nums</i> array is guaranteed to fit within the 32-bit signed integer range.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<strong>Input: </strong><i>nums</i> = <code>[1, -1, 5, -2, 3]</code>, <i>k</i> = <code>3</code>
-<strong>Output: </strong>4 
-<strong>Explanation: </strong>The subarray <code>[1, -1, 5, -2]</code> sums to 3 and is the longest.
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<strong>Input: </strong><i>nums</i> = <code>[-2, -1, 2, 1]</code>, <i>k</i> = <code>1</code>
-<strong>Output: </strong>2 <strong>
-Explanation: </strong>The subarray <code>[-1, 2]</code> sums to 1 and is the longest.</pre>
-
-<p><b>Follow Up:</b><br />
-Can you do it in O(<i>n</i>) time?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [Minimum Size Subarray Sum](../minimum-size-subarray-sum) (Medium)
-  1. [Range Sum Query - Immutable](../range-sum-query-immutable) (Easy)
-  1. [Contiguous Array](../contiguous-array) (Medium)
-  1. [Subarray Product Less Than K](../subarray-product-less-than-k) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to compute a sum of a subsequence very fast, i.e in <i>O(1)</i> … Think of prefix sum array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Given <i>S[i]</i> a partial sum that starts at position <i>0</i> and ends at <i>i</i>, what can <i>S[i - k]</i> tell you ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use HashMap + prefix sum array.
-</details>
diff --git a/problems/maximum-size-subarray-sum-equals-k/maximum_size_subarray_sum_equals_k.go b/problems/maximum-size-subarray-sum-equals-k/maximum_size_subarray_sum_equals_k.go
deleted file mode 100644
index 8ee420ff0..000000000
--- a/problems/maximum-size-subarray-sum-equals-k/maximum_size_subarray_sum_equals_k.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem325
diff --git a/problems/maximum-size-subarray-sum-equals-k/maximum_size_subarray_sum_equals_k_test.go b/problems/maximum-size-subarray-sum-equals-k/maximum_size_subarray_sum_equals_k_test.go
deleted file mode 100644
index 8ee420ff0..000000000
--- a/problems/maximum-size-subarray-sum-equals-k/maximum_size_subarray_sum_equals_k_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem325
diff --git a/problems/maximum-students-taking-exam/README.md b/problems/maximum-students-taking-exam/README.md
deleted file mode 100644
index 5b38f2519..000000000
--- a/problems/maximum-students-taking-exam/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tweet-counts-per-frequency "Tweet Counts Per Frequency")
-　　　　　　　　　　　　　　　　
-[Next >](../students-with-invalid-departments "Students With Invalid Departments")
-
-## [1349. Maximum Students Taking Exam (Hard)](https://leetcode.com/problems/maximum-students-taking-exam "参加考试的最大学生数")
-
-<p>Given a <code>m&nbsp;* n</code>&nbsp;matrix <code>seats</code>&nbsp;&nbsp;that represent seats distributions&nbsp;in a classroom.&nbsp;If a seat&nbsp;is&nbsp;broken, it is denoted by <code>&#39;#&#39;</code> character otherwise it is denoted by a <code>&#39;.&#39;</code> character.</p>
-
-<p>Students can see the answers of those sitting next to the left, right, upper left and upper right, but he cannot see the answers of the student sitting&nbsp;directly in front or behind him. Return the <strong>maximum </strong>number of students that can take the exam together&nbsp;without any cheating being possible..</p>
-
-<p>Students must be placed in seats in good condition.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img height="200" src="https://assets.leetcode.com/uploads/2020/01/29/image.png" width="339" />
-<pre>
-<strong>Input:</strong> seats = [[&quot;#&quot;,&quot;.&quot;,&quot;#&quot;,&quot;#&quot;,&quot;.&quot;,&quot;#&quot;],
-&nbsp;               [&quot;.&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;.&quot;],
-&nbsp;               [&quot;#&quot;,&quot;.&quot;,&quot;#&quot;,&quot;#&quot;,&quot;.&quot;,&quot;#&quot;]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Teacher can place 4 students in available seats so they don&#39;t cheat on the exam. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> seats = [[&quot;.&quot;,&quot;#&quot;],
-&nbsp;               [&quot;#&quot;,&quot;#&quot;],
-&nbsp;               [&quot;#&quot;,&quot;.&quot;],
-&nbsp;               [&quot;#&quot;,&quot;#&quot;],
-&nbsp;               [&quot;.&quot;,&quot;#&quot;]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Place all students in available seats. 
-
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> seats = [[&quot;#&quot;,&quot;.&quot;,&quot;<strong>.</strong>&quot;,&quot;.&quot;,&quot;#&quot;],
-&nbsp;               [&quot;<strong>.</strong>&quot;,&quot;#&quot;,&quot;<strong>.</strong>&quot;,&quot;#&quot;,&quot;<strong>.</strong>&quot;],
-&nbsp;               [&quot;<strong>.</strong>&quot;,&quot;.&quot;,&quot;#&quot;,&quot;.&quot;,&quot;<strong>.</strong>&quot;],
-&nbsp;               [&quot;<strong>.</strong>&quot;,&quot;#&quot;,&quot;<strong>.</strong>&quot;,&quot;#&quot;,&quot;<strong>.</strong>&quot;],
-&nbsp;               [&quot;#&quot;,&quot;.&quot;,&quot;<strong>.</strong>&quot;,&quot;.&quot;,&quot;#&quot;]]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> Place students in available seats in column 1, 3 and 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>seats</code>&nbsp;contains only characters&nbsp;<code>&#39;.&#39;<font face="sans-serif, Arial, Verdana, Trebuchet MS">&nbsp;and</font></code><code>&#39;#&#39;.</code></li>
-	<li><code>m ==&nbsp;seats.length</code></li>
-	<li><code>n ==&nbsp;seats[i].length</code></li>
-	<li><code>1 &lt;= m &lt;= 8</code></li>
-	<li><code>1 &lt;= n &lt;= 8</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Students in row i only can see exams in row i+1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use Dynamic programming to compute the result given a (current row, bitmask people seated in previous row).
-</details>
diff --git a/problems/maximum-subarray-min-product/README.md b/problems/maximum-subarray-min-product/README.md
deleted file mode 100644
index 79aac2c47..000000000
--- a/problems/maximum-subarray-min-product/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-distance-between-a-pair-of-values "Maximum Distance Between a Pair of Values")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-color-value-in-a-directed-graph "Largest Color Value in a Directed Graph")
-
-## [1856. Maximum Subarray Min-Product (Medium)](https://leetcode.com/problems/maximum-subarray-min-product "子数组最小乘积的最大值")
-
-<p>The <strong>min-product</strong> of an array is equal to the <strong>minimum value</strong> in the array <strong>multiplied by</strong> the array&#39;s <strong>sum</strong>.</p>
-
-<ul>
-	<li>For example, the array <code>[3,2,5]</code> (minimum value is <code>2</code>) has a min-product of <code>2 * (3+2+5) = 2 * 10 = 20</code>.</li>
-</ul>
-
-<p>Given an array of integers <code>nums</code>, return <em>the <strong>maximum min-product</strong> of any <strong>non-empty subarray</strong> of </em><code>nums</code>. Since the answer may be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>Note that the min-product should be maximized <strong>before</strong> performing the modulo operation. Testcases are generated such that the maximum min-product <strong>without</strong> modulo will fit in a <strong>64-bit signed integer</strong>.</p>
-
-<p>A <strong>subarray</strong> is a <strong>contiguous</strong> part of an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,<u>2,3,2</u>]
-<strong>Output:</strong> 14
-<strong>Explanation:</strong> The maximum min-product is achieved with the subarray [2,3,2] (minimum value is 2).
-2 * (2+3+2) = 2 * 7 = 14.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,<u>3,3</u>,1,2]
-<strong>Output:</strong> 18
-<strong>Explanation:</strong> The maximum min-product is achieved with the subarray [3,3] (minimum value is 3).
-3 * (3+3) = 3 * 6 = 18.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,<u>5,6,4</u>,2]
-<strong>Output:</strong> 60
-<strong>Explanation:</strong> The maximum min-product is achieved with the subarray [5,6,4] (minimum value is 4).
-4 * (5+6+4) = 4 * 15 = 60.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is there a way we can sort the elements to simplify the problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we find the maximum min-product for every value in the array?
-</details>
diff --git a/problems/maximum-subarray-sum-after-one-operation/README.md b/problems/maximum-subarray-sum-after-one-operation/README.md
deleted file mode 100644
index 152758454..000000000
--- a/problems/maximum-subarray-sum-after-one-operation/README.md
+++ /dev/null
@@ -1,34 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-partitioning-iv "Palindrome Partitioning IV")
-　　　　　　　　　　　　　　　　
-[Next >](../leetflex-banned-accounts "Leetflex Banned Accounts")
-
-## [1746. Maximum Subarray Sum After One Operation (Medium)](https://leetcode.com/problems/maximum-subarray-sum-after-one-operation "经过一次操作后的最大子数组和")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think about dynamic programming
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Define an array dp[nums.length][2], where dp[i][0] is the max subarray sum including nums[i] and without squaring any element.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-dp[i][1] is the max subarray sum including nums[i] and having only one element squared.
-</details>
diff --git a/problems/maximum-subarray-sum-with-one-deletion/README.md b/problems/maximum-subarray-sum-with-one-deletion/README.md
deleted file mode 100644
index 3e76e709f..000000000
--- a/problems/maximum-subarray-sum-with-one-deletion/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../day-of-the-week "Day of the Week")
-　　　　　　　　　　　　　　　　
-[Next >](../make-array-strictly-increasing "Make Array Strictly Increasing")
-
-## [1186. Maximum Subarray Sum with One Deletion (Medium)](https://leetcode.com/problems/maximum-subarray-sum-with-one-deletion "删除一次得到子数组最大和")
-
-<p>Given an array of integers, return the maximum sum for a <strong>non-empty</strong>&nbsp;subarray (contiguous elements) with at most one element deletion.&nbsp;In other words, you want to choose a subarray and optionally delete one element from it so that there is still at least one element left and the&nbsp;sum of the remaining elements is maximum possible.</p>
-
-<p>Note that the subarray needs to be <strong>non-empty</strong> after deleting one element.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,-2,0,3]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>Because we can choose [1, -2, 0, 3] and drop -2, thus the subarray [1, 0, 3] becomes the maximum value.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,-2,-2,3]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>We just choose [3] and it&#39;s the maximum sum.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [-1,-1,-1,-1]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>&nbsp;The final subarray needs to be non-empty. You can&#39;t choose [-1] and delete -1 from it, then get an empty subarray to make the sum equals to 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= arr[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to solve this problem if no deletions are allowed ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try deleting each element and find the maximum subarray sum to both sides of that element.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-To do that efficiently, use the idea of Kadane's algorithm.
-</details>
diff --git a/problems/maximum-subarray/README.md b/problems/maximum-subarray/README.md
deleted file mode 100644
index 39cdbb54e..000000000
--- a/problems/maximum-subarray/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../n-queens-ii "N-Queens II")
-　　　　　　　　　　　　　　　　
-[Next >](../spiral-matrix "Spiral Matrix")
-
-## [53. Maximum Subarray (Easy)](https://leetcode.com/problems/maximum-subarray "最大子序和")
-
-<p>Given an integer array <code>nums</code>, find the contiguous subarray (containing at least one number) which has the largest sum and return <em>its sum</em>.</p>
-
-<p>A <strong>subarray</strong> is a <strong>contiguous</strong> part of an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-2,1,-3,4,-1,2,1,-5,4]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> [4,-1,2,1] has the largest sum = 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,4,-1,7,8]
-<strong>Output:</strong> 23
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> If you have figured out the <code>O(n)</code> solution, try coding another solution using the <strong>divide and conquer</strong> approach, which is more subtle.</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Best Time to Buy and Sell Stock](../best-time-to-buy-and-sell-stock) (Easy)
-  1. [Maximum Product Subarray](../maximum-product-subarray) (Medium)
-  1. [Degree of an Array](../degree-of-an-array) (Easy)
-  1. [Longest Turbulent Subarray](../longest-turbulent-subarray) (Medium)
diff --git a/problems/maximum-subarray/maximum_subarray.go b/problems/maximum-subarray/maximum_subarray.go
deleted file mode 100644
index 0557af338..000000000
--- a/problems/maximum-subarray/maximum_subarray.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem53
-
-func maxSubArray(nums []int) int {
-	max, current, l := nums[0], nums[0], len(nums)
-	for i := 1; i < l; i++ {
-		if current > 0 {
-			current += nums[i]
-		} else {
-			current = nums[i]
-		}
-		if current > max {
-			max = current
-		}
-	}
-	return max
-}
diff --git a/problems/maximum-subarray/maximum_subarray_test.go b/problems/maximum-subarray/maximum_subarray_test.go
deleted file mode 100644
index d57167732..000000000
--- a/problems/maximum-subarray/maximum_subarray_test.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem53
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMaxSubArray(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{-2, 1, -3, 4, -1, 2, 1, -5, 4},
-			want: 6,
-		},
-	}
-	for _, tt := range tests {
-		got := maxSubArray(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/maximum-sum-bst-in-binary-tree/README.md b/problems/maximum-sum-bst-in-binary-tree/README.md
deleted file mode 100644
index 2cdd3f82f..000000000
--- a/problems/maximum-sum-bst-in-binary-tree/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-zigzag-path-in-a-binary-tree "Longest ZigZag Path in a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../generate-a-string-with-characters-that-have-odd-counts "Generate a String With Characters That Have Odd Counts")
-
-## [1373. Maximum Sum BST in Binary Tree (Hard)](https://leetcode.com/problems/maximum-sum-bst-in-binary-tree "二叉搜索子树的最大键值和")
-
-<p>Given a <strong>binary tree</strong> <code>root</code>, return <em>the maximum sum of all keys of <strong>any</strong> sub-tree which is also a Binary Search Tree (BST)</em>.</p>
-
-<p>Assume a BST is defined as follows:</p>
-
-<ul>
-	<li>The left subtree of a node contains only nodes with keys <strong>less than</strong> the node&#39;s key.</li>
-	<li>The right subtree of a node contains only nodes with keys <strong>greater than</strong> the node&#39;s key.</li>
-	<li>Both the left and right subtrees must also be binary search trees.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/01/30/sample_1_1709.png" style="width: 320px; height: 250px;" /></p>
-
-<pre>
-<strong>Input:</strong> root = [1,4,3,2,4,2,5,null,null,null,null,null,null,4,6]
-<strong>Output:</strong> 20
-<strong>Explanation:</strong> Maximum sum in a valid Binary search tree is obtained in root node with key equal to 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/01/30/sample_2_1709.png" style="width: 134px; height: 180px;" /></p>
-
-<pre>
-<strong>Input:</strong> root = [4,3,null,1,2]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Maximum sum in a valid Binary search tree is obtained in a single root node with key equal to 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [-4,-2,-5]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> All values are negatives. Return an empty BST.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 4 * 10<sup>4</sup>]</code>.</li>
-	<li><code>-4 * 10<sup>4</sup> &lt;= Node.val &lt;= 4 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create a datastructure with 4 parameters:  (sum, isBST, maxLeft, minLeft).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In each node compute theses parameters, following the conditions of a Binary Search Tree.
-</details>
diff --git a/problems/maximum-sum-circular-subarray/README.md b/problems/maximum-sum-circular-subarray/README.md
deleted file mode 100644
index 278c2fad3..000000000
--- a/problems/maximum-sum-circular-subarray/README.md
+++ /dev/null
@@ -1,95 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-only-letters "Reverse Only Letters")
-　　　　　　　　　　　　　　　　
-[Next >](../complete-binary-tree-inserter "Complete Binary Tree Inserter")
-
-## [918. Maximum Sum Circular Subarray (Medium)](https://leetcode.com/problems/maximum-sum-circular-subarray "环形子数组的最大和")
-
-<p>Given a <strong>circular integer array</strong> <code>nums</code> of length <code>n</code>, return <em>the maximum possible sum of a non-empty <strong>subarray</strong> of </em><code>nums</code>.</p>
-
-<p>A <strong>circular array</strong> means the end of the array connects to the beginning of the array. Formally, the next element of <code>nums[i]</code> is <code>nums[(i + 1) % n]</code> and the previous element of <code>nums[i]</code> is <code>nums[(i - 1 + n) % n]</code>.</p>
-
-<p>A <strong>subarray</strong> may only include each element of the fixed buffer <code>nums</code> at most once. Formally, for a subarray <code>nums[i], nums[i + 1], ..., nums[j]</code>, there does not exist <code>i &lt;= k1</code>, <code>k2 &lt;= j</code> with <code>k1 % n == k2 % n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,-2,3,-2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Subarray [3] has maximum sum 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,-3,5]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> Subarray [5,5] has maximum sum 5 + 5 = 10
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,-1,2,-1]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Subarray [2,-1,3] has maximum sum 2 + (-1) + 3 = 4
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,-2,2,-3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Subarray [3] and [3,-2,2] both have maximum sum 3
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-2,-3,-1]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> Subarray [-1] has maximum sum -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-3 * 10<sup>4</sup> &lt;= nums[i] &lt;= 3 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Monotonic Queue](../../tag/monotonic-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For those of you who are familiar with the <b>Kadane's algorithm</b>, think in terms of that. For the newbies, Kadane's algorithm is used to finding the maximum sum subarray from a given array. This problem is a twist on that idea and it is advisable to read up on that algorithm first before starting this problem. Unless you already have a great algorithm brewing up in your mind in which case, go right ahead!
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What is an alternate way of representing a circular array so that it appears to be a straight array?
-Essentially, there are two cases of this problem that we need to take care of. Let's look at the figure below to understand those two cases:
-
-<br>
-<img src="https://assets.leetcode.com/uploads/2019/10/20/circular_subarray_hint_1.png" width="700"/>
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The first case can be handled by the good old Kadane's algorithm. However, is there a smarter way of going about handling the second case as well?
-</details>
diff --git a/problems/maximum-sum-circular-subarray/maximum_sum_circular_subarray.go b/problems/maximum-sum-circular-subarray/maximum_sum_circular_subarray.go
deleted file mode 100644
index 626f29fe9..000000000
--- a/problems/maximum-sum-circular-subarray/maximum_sum_circular_subarray.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem918
diff --git a/problems/maximum-sum-circular-subarray/maximum_sum_circular_subarray_test.go b/problems/maximum-sum-circular-subarray/maximum_sum_circular_subarray_test.go
deleted file mode 100644
index 626f29fe9..000000000
--- a/problems/maximum-sum-circular-subarray/maximum_sum_circular_subarray_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem918
diff --git a/problems/maximum-sum-obtained-of-any-permutation/README.md b/problems/maximum-sum-obtained-of-any-permutation/README.md
deleted file mode 100644
index a1d9a7bbb..000000000
--- a/problems/maximum-sum-obtained-of-any-permutation/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-all-odd-length-subarrays "Sum of All Odd Length Subarrays")
-　　　　　　　　　　　　　　　　
-[Next >](../make-sum-divisible-by-p "Make Sum Divisible by P")
-
-## [1589. Maximum Sum Obtained of Any Permutation (Medium)](https://leetcode.com/problems/maximum-sum-obtained-of-any-permutation "所有排列中的最大和")
-
-<p>We have an array of integers, <code>nums</code>, and an array of <code>requests</code> where <code>requests[i] = [start<sub>i</sub>, end<sub>i</sub>]</code>. The <code>i<sup>th</sup></code> request asks for the sum of <code>nums[start<sub>i</sub>] + nums[start<sub>i</sub> + 1] + ... + nums[end<sub>i</sub> - 1] + nums[end<sub>i</sub>]</code>. Both <code>start<sub>i</sub></code> and <code>end<sub>i</sub></code> are <em>0-indexed</em>.</p>
-
-<p>Return <em>the maximum total sum of all requests <strong>among all permutations</strong> of</em> <code>nums</code>.</p>
-
-<p>Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5], requests = [[1,3],[0,1]]
-<strong>Output:</strong> 19
-<strong>Explanation:</strong> One permutation of nums is [2,1,3,4,5] with the following result: 
-requests[0] -&gt; nums[1] + nums[2] + nums[3] = 1 + 3 + 4 = 8
-requests[1] -&gt; nums[0] + nums[1] = 2 + 1 = 3
-Total sum: 8 + 3 = 11.
-A permutation with a higher total sum is [3,5,4,2,1] with the following result:
-requests[0] -&gt; nums[1] + nums[2] + nums[3] = 5 + 4 + 2 = 11
-requests[1] -&gt; nums[0] + nums[1] = 3 + 5  = 8
-Total sum: 11 + 8 = 19, which is the best that you can do.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5,6], requests = [[0,1]]
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> A permutation with the max total sum is [6,5,4,3,2,1] with request sums [11].</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5,10], requests = [[0,2],[1,3],[1,1]]
-<strong>Output:</strong> 47
-<strong>Explanation:</strong> A permutation with the max total sum is [4,10,5,3,2,1] with request sums [19,18,10].</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i]&nbsp;&lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= requests.length &lt;=&nbsp;10<sup>5</sup></code></li>
-	<li><code>requests[i].length == 2</code></li>
-	<li><code>0 &lt;= start<sub>i</sub>&nbsp;&lt;= end<sub>i</sub>&nbsp;&lt;&nbsp;n</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Indexes with higher frequencies should be bound with larger values
-</details>
diff --git a/problems/maximum-sum-of-3-non-overlapping-subarrays/README.md b/problems/maximum-sum-of-3-non-overlapping-subarrays/README.md
deleted file mode 100644
index f29094169..000000000
--- a/problems/maximum-sum-of-3-non-overlapping-subarrays/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../knight-probability-in-chessboard "Knight Probability in Chessboard")
-　　　　　　　　　　　　　　　　
-[Next >](../employee-importance "Employee Importance")
-
-## [689. Maximum Sum of 3 Non-Overlapping Subarrays (Hard)](https://leetcode.com/problems/maximum-sum-of-3-non-overlapping-subarrays "三个无重叠子数组的最大和")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, find three non-overlapping subarrays of length <code>k</code> with maximum sum and return them.</p>
-
-<p>Return the result as a list of indices representing the starting position of each interval (<strong>0-indexed</strong>). If there are multiple answers, return the lexicographically smallest one.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1,2,6,7,5,1], k = 2
-<strong>Output:</strong> [0,3,5]
-<strong>Explanation:</strong> Subarrays [1, 2], [2, 6], [7, 5] correspond to the starting indices [0, 3, 5].
-We could have also taken [2, 1], but an answer of [1, 3, 5] would be lexicographically larger.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1,2,1,2,1,2,1], k = 2
-<strong>Output:</strong> [0,2,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;&nbsp;2<sup>16</sup></code></li>
-	<li><code>1 &lt;= k &lt;= floor(nums.length / 3)</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Best Time to Buy and Sell Stock III](../best-time-to-buy-and-sell-stock-iii) (Hard)
diff --git a/problems/maximum-sum-of-3-non-overlapping-subarrays/maximum_sum_of_3_non_overlapping_subarrays.go b/problems/maximum-sum-of-3-non-overlapping-subarrays/maximum_sum_of_3_non_overlapping_subarrays.go
deleted file mode 100644
index d8e95c634..000000000
--- a/problems/maximum-sum-of-3-non-overlapping-subarrays/maximum_sum_of_3_non_overlapping_subarrays.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem689
diff --git a/problems/maximum-sum-of-3-non-overlapping-subarrays/maximum_sum_of_3_non_overlapping_subarrays_test.go b/problems/maximum-sum-of-3-non-overlapping-subarrays/maximum_sum_of_3_non_overlapping_subarrays_test.go
deleted file mode 100644
index d8e95c634..000000000
--- a/problems/maximum-sum-of-3-non-overlapping-subarrays/maximum_sum_of_3_non_overlapping_subarrays_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem689
diff --git a/problems/maximum-sum-of-two-non-overlapping-subarrays/README.md b/problems/maximum-sum-of-two-non-overlapping-subarrays/README.md
deleted file mode 100644
index b82d688ab..000000000
--- a/problems/maximum-sum-of-two-non-overlapping-subarrays/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../matrix-cells-in-distance-order "Matrix Cells in Distance Order")
-　　　　　　　　　　　　　　　　
-[Next >](../stream-of-characters "Stream of Characters")
-
-## [1031. Maximum Sum of Two Non-Overlapping Subarrays (Medium)](https://leetcode.com/problems/maximum-sum-of-two-non-overlapping-subarrays "两个非重叠子数组的最大和")
-
-<p>Given an integer array <code>nums</code> and two integers <code>firstLen</code> and <code>secondLen</code>, return <em>the maximum sum of elements in two non-overlapping <strong>subarrays</strong> with lengths </em><code>firstLen</code><em> and </em><code>secondLen</code>.</p>
-
-<p>The array with length <code>firstLen</code> could occur before or after the array with length <code>secondLen</code>, but they have to be non-overlapping.</p>
-
-<p>A <strong>subarray</strong> is a <strong>contiguous</strong> part of an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,6,5,2,2,5,1,9,4], firstLen = 1, secondLen = 2
-<strong>Output:</strong> 20
-<strong>Explanation:</strong> One choice of subarrays is [9] with length 1, and [6,5] with length 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,8,1,3,2,1,8,9,0], firstLen = 3, secondLen = 2
-<strong>Output:</strong> 29
-<strong>Explanation:</strong> One choice of subarrays is [3,8,1] with length 3, and [8,9] with length 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,5,6,0,9,5,0,3,8], firstLen = 4, secondLen = 3
-<strong>Output:</strong> 31
-<strong>Explanation:</strong> One choice of subarrays is [5,6,0,9] with length 4, and [3,8] with length 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= firstLen, secondLen &lt;= 1000</code></li>
-	<li><code>2 &lt;= firstLen + secondLen &lt;= 1000</code></li>
-	<li><code>firstLen + secondLen &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can use prefix sums to calculate any subarray sum quickly.
-For each L length subarray, find the best possible M length subarray that occurs before and after it.
-</details>
diff --git a/problems/maximum-sum-of-two-non-overlapping-subarrays/maximum_sum_of_two_non_overlapping_subarrays.go b/problems/maximum-sum-of-two-non-overlapping-subarrays/maximum_sum_of_two_non_overlapping_subarrays.go
deleted file mode 100644
index 64abd8116..000000000
--- a/problems/maximum-sum-of-two-non-overlapping-subarrays/maximum_sum_of_two_non_overlapping_subarrays.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem1031
-
-func maxSumTwoNoOverlap(A []int, L int, M int) int {
-	for i := 1; i < len(A); i++ {
-		A[i] += A[i-1]
-	}
-	// assume original A is A'
-	// now, A[i] = sum(A'[:i+1])
-	res, lMax, mMax := A[L+M-1], A[L-1], A[M-1]
-	for i := L + M; i < len(A); i++ {
-		// lMax is max sum of contiguous L elements before the last M elements.
-		lMax = max(lMax, A[i-M]-A[i-L-M])
-		// mMax is max sum of contiguous M elements before the last L elements.
-		mMax = max(mMax, A[i-L]-A[i-L-M])
-		res = max(res, max(lMax+A[i]-A[i-M], mMax+A[i]-A[i-L]))
-	}
-	return res
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/maximum-swap/README.md b/problems/maximum-swap/README.md
deleted file mode 100644
index 5e5f6da0c..000000000
--- a/problems/maximum-swap/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../trim-a-binary-search-tree "Trim a Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../second-minimum-node-in-a-binary-tree "Second Minimum Node In a Binary Tree")
-
-## [670. Maximum Swap (Medium)](https://leetcode.com/problems/maximum-swap "最大交换")
-
-<p>You are given an integer <code>num</code>. You can swap two digits at most once to get the maximum valued number.</p>
-
-<p>Return <em>the maximum valued number you can get</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 2736
-<strong>Output:</strong> 7236
-<strong>Explanation:</strong> Swap the number 2 and the number 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 9973
-<strong>Output:</strong> 9973
-<strong>Explanation:</strong> No swap.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= num &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Create Maximum Number](../create-maximum-number) (Hard)
diff --git a/problems/maximum-swap/maximum_swap.go b/problems/maximum-swap/maximum_swap.go
deleted file mode 100644
index 231cc862c..000000000
--- a/problems/maximum-swap/maximum_swap.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem670
diff --git a/problems/maximum-swap/maximum_swap_test.go b/problems/maximum-swap/maximum_swap_test.go
deleted file mode 100644
index 231cc862c..000000000
--- a/problems/maximum-swap/maximum_swap_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem670
diff --git a/problems/maximum-transaction-each-day/README.md b/problems/maximum-transaction-each-day/README.md
deleted file mode 100644
index 977486d49..000000000
--- a/problems/maximum-transaction-each-day/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-operations-to-make-string-sorted "Minimum Number of Operations to Make String Sorted")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-the-sentence-is-pangram "Check if the Sentence Is Pangram")
-
-## [1831. Maximum Transaction Each Day (Medium)](https://leetcode.com/problems/maximum-transaction-each-day "每天的最大交易")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/maximum-transaction-each-day/mysql_schemas.sql b/problems/maximum-transaction-each-day/mysql_schemas.sql
deleted file mode 100644
index db8df0ca0..000000000
--- a/problems/maximum-transaction-each-day/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Transactions (transaction_id int, day datetime, amount int);
-Truncate table Transactions;
-insert into Transactions (transaction_id, day, amount) values ('8', '2021-4-3 15:57:28', '57');
-insert into Transactions (transaction_id, day, amount) values ('9', '2021-4-28 08:47:25', '21');
-insert into Transactions (transaction_id, day, amount) values ('1', '2021-4-29 13:28:30', '58');
-insert into Transactions (transaction_id, day, amount) values ('5', '2021-4-28 16:39:59', '40');
-insert into Transactions (transaction_id, day, amount) values ('6', '2021-4-29 23:39:28', '58');
diff --git a/problems/maximum-twin-sum-of-a-linked-list/README.md b/problems/maximum-twin-sum-of-a-linked-list/README.md
deleted file mode 100644
index 03df5b91f..000000000
--- a/problems/maximum-twin-sum-of-a-linked-list/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../capitalize-the-title "Capitalize the Title")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-palindrome-by-concatenating-two-letter-words "Longest Palindrome by Concatenating Two Letter Words")
-
-## [2130. Maximum Twin Sum of a Linked List (Medium)](https://leetcode.com/problems/maximum-twin-sum-of-a-linked-list "链表最大孪生和")
-
-<p>In a linked list of size <code>n</code>, where <code>n</code> is <strong>even</strong>, the <code>i<sup>th</sup></code> node (<strong>0-indexed</strong>) of the linked list is known as the <strong>twin</strong> of the <code>(n-1-i)<sup>th</sup></code> node, if <code>0 &lt;= i &lt;= (n / 2) - 1</code>.</p>
-
-<ul>
-	<li>For example, if <code>n = 4</code>, then node <code>0</code> is the twin of node <code>3</code>, and node <code>1</code> is the twin of node <code>2</code>. These are the only nodes with twins for <code>n = 4</code>.</li>
-</ul>
-
-<p>The <strong>twin sum </strong>is defined as the sum of a node and its twin.</p>
-
-<p>Given the <code>head</code> of a linked list with even length, return <em>the <strong>maximum twin sum</strong> of the linked list</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/03/eg1drawio.png" style="width: 250px; height: 70px;" />
-<pre>
-<strong>Input:</strong> head = [5,4,2,1]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong>
-Nodes 0 and 1 are the twins of nodes 3 and 2, respectively. All have twin sum = 6.
-There are no other nodes with twins in the linked list.
-Thus, the maximum twin sum of the linked list is 6. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/03/eg2drawio.png" style="width: 250px; height: 70px;" />
-<pre>
-<strong>Input:</strong> head = [4,2,2,3]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong>
-The nodes with twins present in this linked list are:
-- Node 0 is the twin of node 3 having a twin sum of 4 + 3 = 7.
-- Node 1 is the twin of node 2 having a twin sum of 2 + 2 = 4.
-Thus, the maximum twin sum of the linked list is max(7, 4) = 7. 
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/03/eg3drawio.png" style="width: 200px; height: 88px;" />
-<pre>
-<strong>Input:</strong> head = [1,100000]
-<strong>Output:</strong> 100001
-<strong>Explanation:</strong>
-There is only one node with a twin in the linked list having twin sum of 1 + 100000 = 100001.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is an <strong>even</strong> integer in the range <code>[2, 10<sup>5</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can "reversing" a part of the linked list help find the answer?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We know that the nodes of the first half are twins of nodes in the second half, so try dividing the linked list in half and reverse the second half.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How can two pointers be used to find every twin sum optimally?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use two different pointers pointing to the first nodes of the two halves of the linked list. The second pointer will point to the first node of the reversed half, which is the (n-1-i)th node in the original linked list. By moving both pointers forward at the same time, we find all twin sums.
-</details>
diff --git a/problems/maximum-units-on-a-truck/README.md b/problems/maximum-units-on-a-truck/README.md
deleted file mode 100644
index e08582c6e..000000000
--- a/problems/maximum-units-on-a-truck/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../biggest-window-between-visits "Biggest Window Between Visits")
-　　　　　　　　　　　　　　　　
-[Next >](../count-good-meals "Count Good Meals")
-
-## [1710. Maximum Units on a Truck (Easy)](https://leetcode.com/problems/maximum-units-on-a-truck "卡车上的最大单元数")
-
-<p>You are assigned to put some amount of boxes onto <strong>one truck</strong>. You are given a 2D array <code>boxTypes</code>, where <code>boxTypes[i] = [numberOfBoxes<sub>i</sub>, numberOfUnitsPerBox<sub>i</sub>]</code>:</p>
-
-<ul>
-	<li><code>numberOfBoxes<sub>i</sub></code> is the number of boxes of type <code>i</code>.</li>
-	<li><code>numberOfUnitsPerBox<sub>i</sub></code><sub> </sub>is the number of units in each box of the type <code>i</code>.</li>
-</ul>
-
-<p>You are also given an integer <code>truckSize</code>, which is the <strong>maximum</strong> number of <strong>boxes</strong> that can be put on the truck. You can choose any boxes to put on the truck as long as the number&nbsp;of boxes does not exceed <code>truckSize</code>.</p>
-
-<p>Return <em>the <strong>maximum</strong> total number of <strong>units</strong> that can be put on the truck.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxTypes = [[1,3],[2,2],[3,1]], truckSize = 4
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> There are:
-- 1 box of the first type that contains 3 units.
-- 2 boxes of the second type that contain 2 units each.
-- 3 boxes of the third type that contain 1 unit each.
-You can take all the boxes of the first and second types, and one box of the third type.
-The total number of units will be = (1 * 3) + (2 * 2) + (1 * 1) = 8.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxTypes = [[5,10],[2,5],[4,7],[3,9]], truckSize = 10
-<strong>Output:</strong> 91
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= boxTypes.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= numberOfBoxes<sub>i</sub>, numberOfUnitsPerBox<sub>i</sub> &lt;= 1000</code></li>
-	<li><code>1 &lt;= truckSize &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If we have space for at least one box, it's always optimal to put the box with the most units.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort the box types with the number of units per box non-increasingly.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Iterate on the box types and take from each type as many as you can.
-</details>
diff --git a/problems/maximum-vacation-days/README.md b/problems/maximum-vacation-days/README.md
deleted file mode 100644
index 6d4ea8813..000000000
--- a/problems/maximum-vacation-days/README.md
+++ /dev/null
@@ -1,96 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../permutation-in-string "Permutation in String")
-　　　　　　　　　　　　　　　　
-[Next >](../median-employee-salary "Median Employee Salary")
-
-## [568. Maximum Vacation Days (Hard)](https://leetcode.com/problems/maximum-vacation-days "最大休假天数")
-
-<p>
-LeetCode wants to give one of its best employees the option to travel among <b>N</b> cities to collect algorithm problems. But all work and no play makes Jack a dull boy, you could take vacations in some particular cities and weeks. Your job is to schedule the traveling to maximize the number of vacation days you could take, but there are certain rules and restrictions you need to follow.
-</p>
-
-<p><b>Rules and restrictions:</b><br>
-<ol>
-<li>You can only travel among <b>N</b> cities, represented by indexes from 0 to N-1. Initially, you are in the city indexed 0 on <b>Monday</b>.</li>
-<li>The cities are connected by flights. The flights are represented as a <b>N*N</b> matrix (not necessary symmetrical), called <b>flights</b> representing the airline status from the city i to the city j. If there is no flight from the city i to the city j, <b>flights[i][j] = 0</b>; Otherwise, <b>flights[i][j] = 1</b>. Also, <b>flights[i][i] = 0</b> for all i.</li>
-<li>You totally have <b>K</b> weeks (<b>each week has 7 days</b>) to travel. You can only take flights at most once <b>per day</b> and can only take flights on each week's <b>Monday</b> morning. Since flight time is so short, we don't consider the impact of flight time.</li>
-<li>For each city, you can only have restricted vacation days in different weeks, given an <b>N*K</b> matrix called <b>days</b> representing this relationship. For the value of <b>days[i][j]</b>, it represents the maximum days you could take vacation in the city <b>i</b> in the week <b>j</b>.</li>
-</ol>
-</p>
-
-<p>You're given the <b>flights</b> matrix and <b>days</b> matrix, and you need to output the maximum vacation days you could take during <b>K</b> weeks.</p>
-
-<p><b>Example 1:</b><br />
-<pre>
-<b>Input:</b>flights = [[0,1,1],[1,0,1],[1,1,0]], days = [[1,3,1],[6,0,3],[3,3,3]]
-<b>Output:</b> 12
-<b>Explanation:</b> <br>Ans = 6 + 3 + 3 = 12. <br>
-One of the best strategies is:
-1st week : fly from city 0 to city 1 on Monday, and play 6 days and work 1 day. <br/>(Although you start at city 0, we could also fly to and start at other cities since it is Monday.) 
-2nd week : fly from city 1 to city 2 on Monday, and play 3 days and work 4 days.
-3rd week : stay at city 2, and play 3 days and work 4 days.
-</pre>
-</p>
-
-<p><b>Example 2:</b><br />
-<pre>
-<b>Input:</b>flights = [[0,0,0],[0,0,0],[0,0,0]], days = [[1,1,1],[7,7,7],[7,7,7]]
-<b>Output:</b> 3
-<b>Explanation:</b> <br>Ans = 1 + 1 + 1 = 3. <br>
-Since there is no flights enable you to move to another city, you have to stay at city 0 for the whole 3 weeks. <br/>For each week, you only have one day to play and six days to work. <br/>So the maximum number of vacation days is 3.
-</pre>
-</p>
-
-<p><b>Example 3:</b><br />
-<pre>
-<b>Input:</b>flights = [[0,1,1],[1,0,1],[1,1,0]], days = [[7,0,0],[0,7,0],[0,0,7]]
-<b>Output:</b> 21
-<b>Explanation:</b><br>Ans = 7 + 7 + 7 = 21<br>
-One of the best strategies is:
-1st week : stay at city 0, and play 7 days. 
-2nd week : fly from city 0 to city 1 on Monday, and play 7 days.
-3rd week : fly from city 1 to city 2 on Monday, and play 7 days.
-</pre>
-</p>
-
-
-<p><b>Note:</b><br>
-<ol>
-<li><b>N and K</b> are positive integers, which are in the range of [1, 100].</li>
-<li>In the matrix <b>flights</b>, all the values are integers in the range of [0, 1].</li>
-<li>In the matrix <b>days</b>, all the values are integers in the range [0, 7].</li>
-<li>You could stay at a city beyond the number of vacation days, but you should <b>work</b> on the extra days, which won't be counted as vacation days.</li>
-<li>If you fly from the city A to the city B and take the vacation on that day, the deduction towards vacation days will count towards the vacation days of city B in that week.</li>
-<li>We don't consider the impact of flight hours towards the calculation of vacation days.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Cheapest Flights Within K Stops](../cheapest-flights-within-k-stops) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First try to understand the problem carefully and then take some example and solve it on a paper.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you interpret the given input as a graph? Which graph traversal technique is suitable here?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Can we use some space to avoid redundant function calls?
-</details>
diff --git a/problems/maximum-vacation-days/maximum_vacation_days.go b/problems/maximum-vacation-days/maximum_vacation_days.go
deleted file mode 100644
index 1c887ad98..000000000
--- a/problems/maximum-vacation-days/maximum_vacation_days.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem568
diff --git a/problems/maximum-vacation-days/maximum_vacation_days_test.go b/problems/maximum-vacation-days/maximum_vacation_days_test.go
deleted file mode 100644
index 1c887ad98..000000000
--- a/problems/maximum-vacation-days/maximum_vacation_days_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem568
diff --git a/problems/maximum-value-after-insertion/README.md b/problems/maximum-value-after-insertion/README.md
deleted file mode 100644
index 9d453f146..000000000
--- a/problems/maximum-value-after-insertion/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-word-equals-summation-of-two-words "Check if Word Equals Summation of Two Words")
-　　　　　　　　　　　　　　　　
-[Next >](../process-tasks-using-servers "Process Tasks Using Servers")
-
-## [1881. Maximum Value after Insertion (Medium)](https://leetcode.com/problems/maximum-value-after-insertion "插入后的最大值")
-
-<p>You are given a very large integer <code>n</code>, represented as a string,​​​​​​ and an integer digit <code>x</code>. The digits in <code>n</code> and the digit <code>x</code> are in the <strong>inclusive</strong> range <code>[1, 9]</code>, and <code>n</code> may represent a <b>negative</b> number.</p>
-
-<p>You want to <strong>maximize </strong><code>n</code><strong>&#39;s numerical value</strong> by inserting <code>x</code> anywhere in the decimal representation of <code>n</code>​​​​​​. You <strong>cannot</strong> insert <code>x</code> to the left of the negative sign.</p>
-
-<ul>
-	<li>For example, if <code>n = 73</code> and <code>x = 6</code>, it would be best to insert it between <code>7</code> and <code>3</code>, making <code>n = 763</code>.</li>
-	<li>If <code>n = -55</code> and <code>x = 2</code>, it would be best to insert it before the first <code>5</code>, making <code>n = -255</code>.</li>
-</ul>
-
-<p>Return <em>a string representing the <strong>maximum</strong> value of </em><code>n</code><em>​​​​​​ after the insertion</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;99&quot;, x = 9
-<strong>Output:</strong> &quot;999&quot;
-<strong>Explanation:</strong> The result is the same regardless of where you insert 9.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;-13&quot;, x = 2
-<strong>Output:</strong> &quot;-123&quot;
-<strong>Explanation:</strong> You can make n one of {-213, -123, -132}, and the largest of those three is -123.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= x &lt;= 9</code></li>
-	<li>The digits in <code>n</code>​​​ are in the range <code>[1, 9]</code>.</li>
-	<li><code>n</code> is a valid representation of an integer.</li>
-	<li>In the case of a negative <code>n</code>,​​​​​​ it will begin with <code>&#39;-&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that if the number is negative it's the same as positive but you look for the minimum instead.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In the case of maximum, if s[i] < x it's optimal that x is put before s[i].
-</details>
-
-<details>
-<summary>Hint 3</summary>
-In the case of minimum, if s[i] > x it's optimal that x is put before s[i].
-</details>
diff --git a/problems/maximum-value-at-a-given-index-in-a-bounded-array/README.md b/problems/maximum-value-at-a-given-index-in-a-bounded-array/README.md
deleted file mode 100644
index 885b19f5f..000000000
--- a/problems/maximum-value-at-a-given-index-in-a-bounded-array/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-orders-in-the-backlog "Number of Orders in the Backlog")
-　　　　　　　　　　　　　　　　
-[Next >](../count-pairs-with-xor-in-a-range "Count Pairs With XOR in a Range")
-
-## [1802. Maximum Value at a Given Index in a Bounded Array (Medium)](https://leetcode.com/problems/maximum-value-at-a-given-index-in-a-bounded-array "有界数组中指定下标处的最大值")
-
-<p>You are given three positive integers:&nbsp;<code>n</code>, <code>index</code>, and <code>maxSum</code>. You want to construct an array <code>nums</code> (<strong>0-indexed</strong>)<strong> </strong>that satisfies the following conditions:</p>
-
-<ul>
-	<li><code>nums.length == n</code></li>
-	<li><code>nums[i]</code> is a <strong>positive</strong> integer where <code>0 &lt;= i &lt; n</code>.</li>
-	<li><code>abs(nums[i] - nums[i+1]) &lt;= 1</code> where <code>0 &lt;= i &lt; n-1</code>.</li>
-	<li>The sum of all the elements of <code>nums</code> does not exceed <code>maxSum</code>.</li>
-	<li><code>nums[index]</code> is <strong>maximized</strong>.</li>
-</ul>
-
-<p>Return <code>nums[index]</code><em> of the constructed array</em>.</p>
-
-<p>Note that <code>abs(x)</code> equals <code>x</code> if <code>x &gt;= 0</code>, and <code>-x</code> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, index = 2,  maxSum = 6
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> nums = [1,2,<u><strong>2</strong></u>,1] is one array that satisfies all the conditions.
-There are no arrays that satisfy all the conditions and have nums[2] == 3, so 2 is the maximum nums[2].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6, index = 1,  maxSum = 10
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= maxSum &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= index &lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if the problem was instead determining if you could generate a valid array with nums[index] == target?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To generate the array, set nums[index] to target, nums[index-i] to target-i, and nums[index+i] to target-i. Then, this will give the minimum possible sum, so check if the sum is less than or equal to maxSum.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-n is too large to actually generate the array, so you can use the formula 1 + 2 + ... + n = n * (n+1) / 2 to quickly find the sum of nums[0...index] and nums[index...n-1].
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Binary search for the target. If it is possible, then move the lower bound up. Otherwise, move the upper bound down.
-</details>
diff --git a/problems/maximum-width-of-binary-tree/README.md b/problems/maximum-width-of-binary-tree/README.md
deleted file mode 100644
index 4678761e5..000000000
--- a/problems/maximum-width-of-binary-tree/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../image-smoother "Image Smoother")
-　　　　　　　　　　　　　　　　
-[Next >](../equal-tree-partition "Equal Tree Partition")
-
-## [662. Maximum Width of Binary Tree (Medium)](https://leetcode.com/problems/maximum-width-of-binary-tree "二叉树最大宽度")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the <strong>maximum width</strong> of the given tree</em>.</p>
-
-<p>The <strong>maximum width</strong> of a tree is the maximum <strong>width</strong> among all levels.</p>
-
-<p>The <strong>width</strong> of one level is defined as the length between the end-nodes (the leftmost and rightmost non-null nodes), where the null nodes between the end-nodes are also counted into the length calculation.</p>
-
-<p>It is <strong>guaranteed</strong> that the answer will in the range of <strong>32-bit</strong> signed integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/width1-tree.jpg" style="width: 359px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [1,3,2,5,3,null,9]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The maximum width existing in the third level with the length 4 (5,3,null,9).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/width2-tree.jpg" style="width: 224px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [1,3,null,5,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The maximum width existing in the third level with the length 2 (5,3).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/width3-tree.jpg" style="width: 289px; height: 299px;" />
-<pre>
-<strong>Input:</strong> root = [1,3,2,5]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The maximum width existing in the second level with the length 2 (3,2).
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/width4-tree.jpg" style="width: 500px; height: 244px;" />
-<pre>
-<strong>Input:</strong> root = [1,3,2,5,null,null,9,6,null,null,7]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> The maximum width existing in the fourth level with the length 8 (6,null,null,null,null,null,null,7).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 3000]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/maximum-width-of-binary-tree/maximum_width_of_binary_tree.go b/problems/maximum-width-of-binary-tree/maximum_width_of_binary_tree.go
deleted file mode 100644
index 07e7616cf..000000000
--- a/problems/maximum-width-of-binary-tree/maximum_width_of_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem662
diff --git a/problems/maximum-width-of-binary-tree/maximum_width_of_binary_tree_test.go b/problems/maximum-width-of-binary-tree/maximum_width_of_binary_tree_test.go
deleted file mode 100644
index 07e7616cf..000000000
--- a/problems/maximum-width-of-binary-tree/maximum_width_of_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem662
diff --git a/problems/maximum-width-ramp/README.md b/problems/maximum-width-ramp/README.md
deleted file mode 100644
index 90711b88d..000000000
--- a/problems/maximum-width-ramp/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../n-repeated-element-in-size-2n-array "N-Repeated Element in Size 2N Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-area-rectangle-ii "Minimum Area Rectangle II")
-
-## [962. Maximum Width Ramp (Medium)](https://leetcode.com/problems/maximum-width-ramp "最大宽度坡")
-
-<p>A <strong>ramp</strong> in an integer array <code>nums</code> is a pair <code>(i, j)</code> for which <code>i &lt; j</code> and <code>nums[i] &lt;= nums[j]</code>. The <strong>width</strong> of such a ramp is <code>j - i</code>.</p>
-
-<p>Given an integer array <code>nums</code>, return <em>the maximum width of a <strong>ramp</strong> in </em><code>nums</code>. If there is no <strong>ramp</strong> in <code>nums</code>, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [6,0,8,2,1,5]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The maximum width ramp is achieved at (i, j) = (1, 5): nums[1] = 0 and nums[5] = 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,8,1,0,1,9,4,0,4,1]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The maximum width ramp is achieved at (i, j) = (2, 9): nums[2] = 1 and nums[9] = 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 5 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
diff --git a/problems/maximum-width-ramp/maximum_width_ramp.go b/problems/maximum-width-ramp/maximum_width_ramp.go
deleted file mode 100644
index 0b918adf2..000000000
--- a/problems/maximum-width-ramp/maximum_width_ramp.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem962
-
-func maxWidthRamp(A []int) int {
-	return 0
-}
diff --git a/problems/maximum-xor-for-each-query/README.md b/problems/maximum-xor-for-each-query/README.md
deleted file mode 100644
index 77772fb9e..000000000
--- a/problems/maximum-xor-for-each-query/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../queries-on-number-of-points-inside-a-circle "Queries on Number of Points Inside a Circle")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-operations-to-make-string-sorted "Minimum Number of Operations to Make String Sorted")
-
-## [1829. Maximum XOR for Each Query (Medium)](https://leetcode.com/problems/maximum-xor-for-each-query "每个查询的最大异或值")
-
-<p>You are given a <strong>sorted</strong> array <code>nums</code> of <code>n</code> non-negative integers and an integer <code>maximumBit</code>. You want to perform the following query <code>n</code> <strong>times</strong>:</p>
-
-<ol>
-	<li>Find a non-negative integer <code>k &lt; 2<sup>maximumBit</sup></code> such that <code>nums[0] XOR nums[1] XOR ... XOR nums[nums.length-1] XOR k</code> is <strong>maximized</strong>. <code>k</code> is the answer to the <code>i<sup>th</sup></code> query.</li>
-	<li>Remove the <strong>last </strong>element from the current array <code>nums</code>.</li>
-</ol>
-
-<p>Return <em>an array</em> <code>answer</code><em>, where </em><code>answer[i]</code><em> is the answer to the </em><code>i<sup>th</sup></code><em> query</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,1,3], maximumBit = 2
-<strong>Output:</strong> [0,3,2,3]
-<strong>Explanation</strong>: The queries are answered as follows:
-1<sup>st</sup> query: nums = [0,1,1,3], k = 0 since 0 XOR 1 XOR 1 XOR 3 XOR 0 = 3.
-2<sup>nd</sup> query: nums = [0,1,1], k = 3 since 0 XOR 1 XOR 1 XOR 3 = 3.
-3<sup>rd</sup> query: nums = [0,1], k = 2 since 0 XOR 1 XOR 2 = 3.
-4<sup>th</sup> query: nums = [0], k = 3 since 0 XOR 3 = 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,4,7], maximumBit = 3
-<strong>Output:</strong> [5,2,6,5]
-<strong>Explanation</strong>: The queries are answered as follows:
-1<sup>st</sup> query: nums = [2,3,4,7], k = 5 since 2 XOR 3 XOR 4 XOR 7 XOR 5 = 7.
-2<sup>nd</sup> query: nums = [2,3,4], k = 2 since 2 XOR 3 XOR 4 XOR 2 = 7.
-3<sup>rd</sup> query: nums = [2,3], k = 6 since 2 XOR 3 XOR 6 = 7.
-4<sup>th</sup> query: nums = [2], k = 5 since 2 XOR 5 = 7.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,2,2,5,7], maximumBit = 3
-<strong>Output:</strong> [4,3,6,4,6,7]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>nums.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= maximumBit &lt;= 20</code></li>
-	<li><code>0 &lt;= nums[i] &lt; 2<sup>maximumBit</sup></code></li>
-	<li><code>nums</code>​​​ is sorted in <strong>ascending</strong> order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that the maximum possible XOR result is always 2^(maximumBit) - 1
-</details>
-
-<details>
-<summary>Hint 2</summary>
-So the answer for a prefix is the XOR of that prefix XORed with 2^(maximumBit)-1
-</details>
diff --git a/problems/maximum-xor-of-two-numbers-in-an-array/README.md b/problems/maximum-xor-of-two-numbers-in-an-array/README.md
deleted file mode 100644
index 2457f9950..000000000
--- a/problems/maximum-xor-of-two-numbers-in-an-array/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../strong-password-checker "Strong Password Checker")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-word-square "Valid Word Square")
-
-## [421. Maximum XOR of Two Numbers in an Array (Medium)](https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array "数组中两个数的最大异或值")
-
-<p>Given an integer array <code>nums</code>, return <em>the maximum result of </em><code>nums[i] XOR nums[j]</code>, where <code>0 &lt;= i &lt;= j &lt; n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,10,5,25,2,8]
-<strong>Output:</strong> 28
-<strong>Explanation:</strong> The maximum result is 5 XOR 25 = 28.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0]
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,4]
-<strong>Output:</strong> 6
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [8,10,2]
-<strong>Output:</strong> 10
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [14,70,53,83,49,91,36,80,92,51,66,70]
-<strong>Output:</strong> 127
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Similar Questions
-  1. [Maximum XOR With an Element From Array](../maximum-xor-with-an-element-from-array) (Hard)
diff --git a/problems/maximum-xor-of-two-numbers-in-an-array/maximum_xor_of_two_numbers_in_an_array.go b/problems/maximum-xor-of-two-numbers-in-an-array/maximum_xor_of_two_numbers_in_an_array.go
deleted file mode 100644
index 2ee713361..000000000
--- a/problems/maximum-xor-of-two-numbers-in-an-array/maximum_xor_of_two_numbers_in_an_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem421
diff --git a/problems/maximum-xor-of-two-numbers-in-an-array/maximum_xor_of_two_numbers_in_an_array_test.go b/problems/maximum-xor-of-two-numbers-in-an-array/maximum_xor_of_two_numbers_in_an_array_test.go
deleted file mode 100644
index 2ee713361..000000000
--- a/problems/maximum-xor-of-two-numbers-in-an-array/maximum_xor_of_two_numbers_in_an_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem421
diff --git a/problems/maximum-xor-with-an-element-from-array/README.md b/problems/maximum-xor-with-an-element-from-array/README.md
deleted file mode 100644
index daa3f0add..000000000
--- a/problems/maximum-xor-with-an-element-from-array/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../where-will-the-ball-fall "Where Will the Ball Fall")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-subarray-length-k "Largest Subarray Length K")
-
-## [1707. Maximum XOR With an Element From Array (Hard)](https://leetcode.com/problems/maximum-xor-with-an-element-from-array "与数组中元素的最大异或值")
-
-<p>You are given an array <code>nums</code> consisting of non-negative integers. You are also given a <code>queries</code> array, where <code>queries[i] = [x<sub>i</sub>, m<sub>i</sub>]</code>.</p>
-
-<p>The answer to the <code>i<sup>th</sup></code> query is the maximum bitwise <code>XOR</code> value of <code>x<sub>i</sub></code> and any element of <code>nums</code> that does not exceed <code>m<sub>i</sub></code>. In other words, the answer is <code>max(nums[j] XOR x<sub>i</sub>)</code> for all <code>j</code> such that <code>nums[j] &lt;= m<sub>i</sub></code>. If all elements in <code>nums</code> are larger than <code>m<sub>i</sub></code>, then the answer is <code>-1</code>.</p>
-
-<p>Return <em>an integer array </em><code>answer</code><em> where </em><code>answer.length == queries.length</code><em> and </em><code>answer[i]</code><em> is the answer to the </em><code>i<sup>th</sup></code><em> query.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,2,3,4], queries = [[3,1],[1,3],[5,6]]
-<strong>Output:</strong> [3,3,7]
-<strong>Explanation:</strong>
-1) 0 and 1 are the only two integers not greater than 1. 0 XOR 3 = 3 and 1 XOR 3 = 2. The larger of the two is 3.
-2) 1 XOR 2 = 3.
-3) 5 XOR 2 = 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,2,4,6,6,3], queries = [[12,4],[8,1],[6,3]]
-<strong>Output:</strong> [15,-1,5]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length, queries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>queries[i].length == 2</code></li>
-	<li><code>0 &lt;= nums[j], x<sub>i</sub>, m<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Similar Questions
-  1. [Maximum XOR of Two Numbers in an Array](../maximum-xor-of-two-numbers-in-an-array) (Medium)
-  1. [Maximum Genetic Difference Query](../maximum-genetic-difference-query) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-In problems involving bitwise operations, we often think on the bits level. In this problem, we can think that to maximize the result of an xor operation, we need to maximize the most significant bit, then the next one, and so on.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If there's some number in the array that is less than m and whose the most significant bit is different than that of x, then xoring with this number maximizes the most significant bit, so I know this bit in the answer is 1.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-To check the existence of such numbers and narrow your scope for further bits based on your choice, you can use trie.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-You can sort the array and the queries, and maintain the trie such that in each query the trie consists exactly of the valid elements.
-</details>
diff --git a/problems/mean-of-array-after-removing-some-elements/README.md b/problems/mean-of-array-after-removing-some-elements/README.md
deleted file mode 100644
index a3838f31b..000000000
--- a/problems/mean-of-array-after-removing-some-elements/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-font-to-fit-a-sentence-in-a-screen "Maximum Font to Fit a Sentence in a Screen")
-　　　　　　　　　　　　　　　　
-[Next >](../coordinate-with-maximum-network-quality "Coordinate With Maximum Network Quality")
-
-## [1619. Mean of Array After Removing Some Elements (Easy)](https://leetcode.com/problems/mean-of-array-after-removing-some-elements "删除某些元素后的数组均值")
-
-<p>Given an integer array <code>arr</code>, return <em>the mean of the remaining integers after removing the smallest <code>5%</code> and the largest <code>5%</code> of the elements.</em></p>
-
-<p>Answers within <code>10<sup>-5</sup></code> of the <strong>actual answer</strong> will be considered accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3]
-<strong>Output:</strong> 2.00000
-<strong>Explanation:</strong> After erasing the minimum and the maximum values of this array, all elements are equal to 2, so the mean is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [6,2,7,5,1,2,0,3,10,2,5,0,5,5,0,8,7,6,8,0]
-<strong>Output:</strong> 4.00000
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [6,0,7,0,7,5,7,8,3,4,0,7,8,1,6,8,1,1,2,4,8,1,9,5,4,3,8,5,10,8,6,6,1,0,6,10,8,2,3,4]
-<strong>Output:</strong> 4.77778
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>20 &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>arr.length</code><b> </b><strong>is a multiple</strong> of <code>20</code>.</li>
-	<li><code><font face="monospace">0 &lt;= arr[i] &lt;= 10<sup>5</sup></font></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the given array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Remove the first and last 5% of the sorted array.
-</details>
diff --git a/problems/median-employee-salary/README.md b/problems/median-employee-salary/README.md
deleted file mode 100644
index 90ee0f2bb..000000000
--- a/problems/median-employee-salary/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-vacation-days "Maximum Vacation Days")
-　　　　　　　　　　　　　　　　
-[Next >](../managers-with-at-least-5-direct-reports "Managers with at Least 5 Direct Reports")
-
-## [569. Median Employee Salary (Hard)](https://leetcode.com/problems/median-employee-salary "员工薪水中位数")
-
-<p>The <code>Employee</code> table holds all employees. The employee table has three columns: Employee Id, Company Name, and Salary.</p>
-
-<pre>
-+-----+------------+--------+
-|Id   | Company    | Salary |
-+-----+------------+--------+
-|1    | A          | 2341   |
-|2    | A          | 341    |
-|3    | A          | 15     |
-|4    | A          | 15314  |
-|5    | A          | 451    |
-|6    | A          | 513    |
-|7    | B          | 15     |
-|8    | B          | 13     |
-|9    | B          | 1154   |
-|10   | B          | 1345   |
-|11   | B          | 1221   |
-|12   | B          | 234    |
-|13   | C          | 2345   |
-|14   | C          | 2645   |
-|15   | C          | 2645   |
-|16   | C          | 2652   |
-|17   | C          | 65     |
-+-----+------------+--------+
-</pre>
-
-<p>Write a SQL query to find the median salary of each company. Bonus points if you can solve it without using any built-in SQL functions.</p>
-
-<pre>
-+-----+------------+--------+
-|Id   | Company    | Salary |
-+-----+------------+--------+
-|5    | A          | 451    |
-|6    | A          | 513    |
-|12   | B          | 234    |
-|9    | B          | 1154   |
-|14   | C          | 2645   |
-+-----+------------+--------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Find Median Given Frequency of Numbers](../find-median-given-frequency-of-numbers) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Still remember how to select the sum which group by one column?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to think about how to get the median from a sorted list.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How to get the median one item for odd number list while how to get the median two items for even number list, try to unify them.
-</details>
diff --git a/problems/median-employee-salary/median_employee_salary.sql b/problems/median-employee-salary/median_employee_salary.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/median-employee-salary/median_employee_salary.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/median-employee-salary/mysql_schemas.sql b/problems/median-employee-salary/mysql_schemas.sql
deleted file mode 100644
index 5dd574292..000000000
--- a/problems/median-employee-salary/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create table If Not Exists Employee (id int, company varchar(255), salary int);
-Truncate table Employee;
-insert into Employee (id, company, salary) values ('1', 'A', '2341');
-insert into Employee (id, company, salary) values ('2', 'A', '341');
-insert into Employee (id, company, salary) values ('3', 'A', '15');
-insert into Employee (id, company, salary) values ('4', 'A', '15314');
-insert into Employee (id, company, salary) values ('5', 'A', '451');
-insert into Employee (id, company, salary) values ('6', 'A', '513');
-insert into Employee (id, company, salary) values ('7', 'B', '15');
-insert into Employee (id, company, salary) values ('8', 'B', '13');
-insert into Employee (id, company, salary) values ('9', 'B', '1154');
-insert into Employee (id, company, salary) values ('10', 'B', '1345');
-insert into Employee (id, company, salary) values ('11', 'B', '1221');
-insert into Employee (id, company, salary) values ('12', 'B', '234');
-insert into Employee (id, company, salary) values ('13', 'C', '2345');
-insert into Employee (id, company, salary) values ('14', 'C', '2645');
-insert into Employee (id, company, salary) values ('15', 'C', '2645');
-insert into Employee (id, company, salary) values ('16', 'C', '2652');
-insert into Employee (id, company, salary) values ('17', 'C', '65');
diff --git a/problems/median-of-two-sorted-arrays/README.md b/problems/median-of-two-sorted-arrays/README.md
deleted file mode 100644
index d7d9731fd..000000000
--- a/problems/median-of-two-sorted-arrays/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-substring-without-repeating-characters "Longest Substring Without Repeating Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-palindromic-substring "Longest Palindromic Substring")
-
-## [4. Median of Two Sorted Arrays (Hard)](https://leetcode.com/problems/median-of-two-sorted-arrays "寻找两个正序数组的中位数")
-
-<p>Given two sorted arrays <code>nums1</code> and <code>nums2</code> of size <code>m</code> and <code>n</code> respectively, return <strong>the median</strong> of the two sorted arrays.</p>
-
-<p>The overall run time complexity should be <code>O(log (m+n))</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,3], nums2 = [2]
-<strong>Output:</strong> 2.00000
-<strong>Explanation:</strong> merged array = [1,2,3] and median is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2], nums2 = [3,4]
-<strong>Output:</strong> 2.50000
-<strong>Explanation:</strong> merged array = [1,2,3,4] and median is (2 + 3) / 2 = 2.5.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [0,0], nums2 = [0,0]
-<strong>Output:</strong> 0.00000
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [], nums2 = [1]
-<strong>Output:</strong> 1.00000
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [2], nums2 = []
-<strong>Output:</strong> 2.00000
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>nums1.length == m</code></li>
-	<li><code>nums2.length == n</code></li>
-	<li><code>0 &lt;= m &lt;= 1000</code></li>
-	<li><code>0 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= m + n &lt;= 2000</code></li>
-	<li><code>-10<sup>6</sup> &lt;= nums1[i], nums2[i] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
diff --git a/problems/median-of-two-sorted-arrays/median_of_two_sorted_arrays.go b/problems/median-of-two-sorted-arrays/median_of_two_sorted_arrays.go
deleted file mode 100644
index 352e510c5..000000000
--- a/problems/median-of-two-sorted-arrays/median_of_two_sorted_arrays.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem4
-
-func findMedianSortedArrays(nums1 []int, nums2 []int) float64 {
-	m, n := len(nums1), len(nums2)
-	s := make([]int, 0, m+n)
-	i, j := 0, 0
-	for i < m && j < n {
-		v1 := nums1[i]
-		v2 := nums2[j]
-		if v1 <= v2 {
-			s = append(s, v1)
-			i++
-		} else {
-			s = append(s, v2)
-			j++
-		}
-	}
-	if i < m {
-		s = append(s, nums1[i:]...)
-	} else {
-		s = append(s, nums2[j:]...)
-	}
-	count := m + n
-	if count&1 == 1 {
-		k := (count - 1) / 2
-		return float64(s[k])
-	}
-	k := count / 2
-	return (float64(s[k-1]) + float64(s[k])) / 2
-}
diff --git a/problems/median-of-two-sorted-arrays/median_of_two_sorted_arrays_test.go b/problems/median-of-two-sorted-arrays/median_of_two_sorted_arrays_test.go
deleted file mode 100644
index 6bc60dc53..000000000
--- a/problems/median-of-two-sorted-arrays/median_of_two_sorted_arrays_test.go
+++ /dev/null
@@ -1,81 +0,0 @@
-package problem4
-
-import "testing"
-
-type testType struct {
-	num1 []int
-	num2 []int
-	want float64
-}
-
-func TestFindMedianSortedArrays(t *testing.T) {
-	tests := [...]testType{
-		{
-			num1: []int{1, 3},
-			num2: []int{2},
-			want: 2.0,
-		},
-		{
-			num1: []int{1, 2},
-			num2: []int{3, 4},
-			want: 2.5,
-		},
-		{
-			num1: []int{1, 3, 5, 7},
-			num2: []int{2, 4},
-			want: 3.5,
-		},
-		{
-			num1: []int{1, 3, 5},
-			num2: []int{},
-			want: 3,
-		},
-		{
-			num1: []int{1, 2},
-			num2: []int{3},
-			want: 2,
-		},
-		{
-			num1: []int{1, 1},
-			num2: []int{1, 1},
-			want: 1,
-		},
-		{
-			num1: []int{1, 1, 1},
-			num2: []int{1, 1},
-			want: 1,
-		},
-		{
-			num1: []int{1, 1},
-			num2: []int{1, 1, 1},
-			want: 1,
-		},
-		{
-			num1: []int{1},
-			num2: []int{2, 3, 4},
-			want: 2.5,
-		},
-		{
-			num1: []int{2, 3, 4},
-			num2: []int{1},
-			want: 2.5,
-		},
-		{
-			num1: []int{},
-			num2: []int{1},
-			want: 1,
-		},
-		{
-			num1: []int{},
-			num2: []int{1, 1},
-			want: 1,
-		},
-	}
-
-	for _, tt := range tests {
-		got := findMedianSortedArrays(tt.num1, tt.num2)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.num1, tt.num2, got, tt.want)
-		}
-	}
-}
diff --git a/problems/meeting-rooms-ii/README.md b/problems/meeting-rooms-ii/README.md
deleted file mode 100644
index 03636b0e5..000000000
--- a/problems/meeting-rooms-ii/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../meeting-rooms "Meeting Rooms")
-　　　　　　　　　　　　　　　　
-[Next >](../factor-combinations "Factor Combinations")
-
-## [253. Meeting Rooms II (Medium)](https://leetcode.com/problems/meeting-rooms-ii "会议室 II")
-
-<p>Given an array of meeting time intervals consisting of start and end times <code>[[s1,e1],[s2,e2],...]</code> (s<sub>i</sub> &lt; e<sub>i</sub>), find the minimum number of conference rooms required.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> <code>[[0, 30],[5, 10],[15, 20]]</code>
-<strong>Output:</strong> 2</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<b>Input:</b> [[7,10],[2,4]]
-<b>Output:</b> 1</pre>
-
-<p><strong>NOTE:</strong>&nbsp;input types have been changed on April 15, 2019. Please reset to default code definition to get new method signature.</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Merge Intervals](../merge-intervals) (Medium)
-  1. [Meeting Rooms](../meeting-rooms) (Easy)
-  1. [Minimum Number of Arrows to Burst Balloons](../minimum-number-of-arrows-to-burst-balloons) (Medium)
-  1. [Car Pooling](../car-pooling) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think about how we would approach this problem in a very simplistic way. We will allocate rooms to meetings that occur earlier in the day v/s the ones that occur later on, right?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you've figured out that we have to <b>sort</b> the meetings by their start time, the next thing to think about is how do we do the allocation? <br>There are two scenarios possible here for any meeting. Either there is no meeting room available and a new one has to be allocated, or a meeting room has freed up and this meeting can take place there.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-An important thing to note is that we don't really care <b>which</b> room gets freed up while allocating a room for the current meeting. As long as a room is free, our job is done. <br><br>We already know the rooms we have allocated till now and we also know when are they due to get free because of the end times of the meetings going on in those rooms. We can simply check the room which is due to get vacated the earliest amongst all the allocated rooms.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Following up on the previous hint, we can make use of a min-heap to store the end times of the meetings in various rooms. <br><br>So, every time we want to check if any room is free or not, simply check the topmost element of the min heap as that would be the room that would get free the earliest out of all the other rooms currently occupied.
-
-<br><br>If the room we extracted from the top of the min heap isn't free, then no other room is. So, we can save time here and simply allocate a new room.
-</details>
diff --git a/problems/meeting-rooms-ii/meeting_rooms_ii.go b/problems/meeting-rooms-ii/meeting_rooms_ii.go
deleted file mode 100644
index cc782d17b..000000000
--- a/problems/meeting-rooms-ii/meeting_rooms_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem253
diff --git a/problems/meeting-rooms-ii/meeting_rooms_ii_test.go b/problems/meeting-rooms-ii/meeting_rooms_ii_test.go
deleted file mode 100644
index cc782d17b..000000000
--- a/problems/meeting-rooms-ii/meeting_rooms_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem253
diff --git a/problems/meeting-rooms/README.md b/problems/meeting-rooms/README.md
deleted file mode 100644
index 7138cc5b1..000000000
--- a/problems/meeting-rooms/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flatten-2d-vector "Flatten 2D Vector")
-　　　　　　　　　　　　　　　　
-[Next >](../meeting-rooms-ii "Meeting Rooms II")
-
-## [252. Meeting Rooms (Easy)](https://leetcode.com/problems/meeting-rooms "会议室")
-
-<p>Given an array of meeting time intervals consisting of start and end times <code>[[s1,e1],[s2,e2],...]</code> (s<sub>i</sub> &lt; e<sub>i</sub>), determine if a person could attend all meetings.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<b>Input:</b> <code>[[0,30],[5,10],[15,20]]</code>
-<b>Output:</b> false
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<b>Input:</b> [[7,10],[2,4]]
-<b>Output:</b> true
-</pre>
-
-<p><strong>NOTE:</strong>&nbsp;input types have been changed on April 15, 2019. Please reset to default code definition to get new method signature.</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Merge Intervals](../merge-intervals) (Medium)
-  1. [Meeting Rooms II](../meeting-rooms-ii) (Medium)
diff --git a/problems/meeting-rooms/meeting_rooms.go b/problems/meeting-rooms/meeting_rooms.go
deleted file mode 100644
index 25a1b3bb3..000000000
--- a/problems/meeting-rooms/meeting_rooms.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem252
diff --git a/problems/meeting-rooms/meeting_rooms_test.go b/problems/meeting-rooms/meeting_rooms_test.go
deleted file mode 100644
index 25a1b3bb3..000000000
--- a/problems/meeting-rooms/meeting_rooms_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem252
diff --git a/problems/meeting-scheduler/README.md b/problems/meeting-scheduler/README.md
deleted file mode 100644
index 1c6ac62b7..000000000
--- a/problems/meeting-scheduler/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../missing-number-in-arithmetic-progression "Missing Number In Arithmetic Progression")
-　　　　　　　　　　　　　　　　
-[Next >](../toss-strange-coins "Toss Strange Coins")
-
-## [1229. Meeting Scheduler (Medium)](https://leetcode.com/problems/meeting-scheduler "安排会议日程")
-
-<p>Given the availability time slots arrays&nbsp;<code>slots1</code> and <code>slots2</code>&nbsp;of two people and a meeting duration <code>duration</code>, return the <strong>earliest time slot</strong> that works for both of them and is of duration <code>duration</code>.</p>
-
-<p>If there is no common time slot that satisfies the requirements, return an <strong>empty array</strong>.</p>
-
-<p>The format of a time slot is an array of two elements&nbsp;<code>[start, end]</code>&nbsp;representing an inclusive time range from <code>start</code>&nbsp;to <code>end</code>.&nbsp;&nbsp;</p>
-
-<p>It is guaranteed that no two availability slots of the same person intersect with each other. That is, for any two time slots&nbsp;<code>[start1, end1]</code>&nbsp;and&nbsp;<code>[start2, end2]</code>&nbsp;of the same person, either&nbsp;<code>start1 &gt; end2</code>&nbsp;or&nbsp;<code>start2 &gt; end1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> slots1 = [[10,50],[60,120],[140,210]], slots2 = [[0,15],[60,70]], duration = 8
-<strong>Output:</strong> [60,68]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> slots1 = [[10,50],[60,120],[140,210]], slots2 = [[0,15],[60,70]], duration = 12
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= slots1.length, slots2.length &lt;= 10^4</code></li>
-	<li><code>slots1[i].length, slots2[i].length == 2</code></li>
-	<li><code>slots1[i][0] &lt; slots1[i][1]</code></li>
-	<li><code>slots2[i][0] &lt; slots2[i][1]</code></li>
-	<li><code>0 &lt;= slots1[i][j], slots2[i][j] &lt;= 10^9</code></li>
-	<li><code>1 &lt;= duration &lt;= 10^6&nbsp;</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Assume that in the solution, the selected slot from slotsA is bigger than the respectively selected slot from slotsB.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use two pointers in order to try all the possible intersections, and check the length.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Do the same in step N° 1 but now assume that the selected slot from slotsB is bigger, return the minimum of the two options.
-</details>
diff --git a/problems/merge-bsts-to-create-single-bst/README.md b/problems/merge-bsts-to-create-single-bst/README.md
deleted file mode 100644
index f8271915c..000000000
--- a/problems/merge-bsts-to-create-single-bst/README.md
+++ /dev/null
@@ -1,102 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../painting-a-grid-with-three-different-colors "Painting a Grid With Three Different Colors")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-string-is-decomposable-into-value-equal-substrings "Check if String Is Decomposable Into Value-Equal Substrings")
-
-## [1932. Merge BSTs to Create Single BST (Hard)](https://leetcode.com/problems/merge-bsts-to-create-single-bst "合并多棵二叉搜索树")
-
-<p>You are given <code>n</code> <strong>BST (binary search tree) root nodes</strong> for <code>n</code> separate BSTs stored in an array <code>trees</code> (<strong>0-indexed</strong>). Each BST in <code>trees</code> has <strong>at most 3 nodes</strong>, and no two roots have the same value. In one operation, you can:</p>
-
-<ul>
-	<li>Select two <strong>distinct</strong> indices <code>i</code> and <code>j</code> such that the value stored at one of the <strong>leaves </strong>of <code>trees[i]</code> is equal to the <strong>root value</strong> of <code>trees[j]</code>.</li>
-	<li>Replace the leaf node in <code>trees[i]</code> with <code>trees[j]</code>.</li>
-	<li>Remove <code>trees[j]</code> from <code>trees</code>.</li>
-</ul>
-
-<p>Return<em> the <strong>root</strong> of the resulting BST if it is possible to form a valid BST after performing </em><code>n - 1</code><em> operations, or</em><em> </em><code>null</code> <i>if it is impossible to create a valid BST</i>.</p>
-
-<p>A BST (binary search tree) is a binary tree where each node satisfies the following property:</p>
-
-<ul>
-	<li>Every node in the node&#39;s left subtree has a value&nbsp;<strong>strictly less</strong>&nbsp;than the node&#39;s value.</li>
-	<li>Every node in the node&#39;s right subtree has a value&nbsp;<strong>strictly greater</strong>&nbsp;than the node&#39;s value.</li>
-</ul>
-
-<p>A leaf is a node that has no children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/08/d1.png" style="width: 450px; height: 163px;" />
-<pre>
-<strong>Input:</strong> trees = [[2,1],[3,2,5],[5,4]]
-<strong>Output:</strong> [3,2,5,1,null,4]
-<strong>Explanation:</strong>
-In the first operation, pick i=1 and j=0, and merge trees[0] into trees[1].
-Delete trees[0], so trees = [[3,2,5,1],[5,4]].
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/24/diagram.png" style="width: 450px; height: 181px;" />
-In the second operation, pick i=0 and j=1, and merge trees[1] into trees[0].
-Delete trees[1], so trees = [[3,2,5,1,null,4]].
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/24/diagram-2.png" style="width: 220px; height: 165px;" />
-The resulting tree, shown above, is a valid BST, so return its root.</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/08/d2.png" style="width: 450px; height: 171px;" />
-<pre>
-<strong>Input:</strong> trees = [[5,3,8],[3,2,6]]
-<strong>Output:</strong> []
-<strong>Explanation:</strong>
-Pick i=0 and j=1 and merge trees[1] into trees[0].
-Delete trees[1], so trees = [[5,3,8,2,6]].
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/24/diagram-3.png" style="width: 240px; height: 196px;" />
-The resulting tree is shown above. This is the only valid operation that can be performed, but the resulting tree is not a valid BST, so return null.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/08/d3.png" style="width: 430px; height: 168px;" />
-<pre>
-<strong>Input:</strong> trees = [[5,4],[3]]
-<strong>Output:</strong> []
-<strong>Explanation:</strong> It is impossible to perform any operations.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == trees.length</code></li>
-	<li><code>1 &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-	<li>The number of nodes in each tree is in the range <code>[1, 3]</code>.</li>
-	<li>Each node in the input may have children but no grandchildren.</li>
-	<li>No two roots of <code>trees</code> have the same value.</li>
-	<li>All the trees in the input are <strong>valid BSTs</strong>.</li>
-	<li><code>1 &lt;= TreeNode.val &lt;= 5 * 10<sup>4</sup></code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is it possible to have multiple leaf nodes with the same values?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How many possible positions are there for each tree?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The root value of the final tree does not occur as a value in any of the leaves of the original tree.
-</details>
diff --git a/problems/merge-in-between-linked-lists/README.md b/problems/merge-in-between-linked-lists/README.md
deleted file mode 100644
index 2206ccda2..000000000
--- a/problems/merge-in-between-linked-lists/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-repeating-substring "Maximum Repeating Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../design-front-middle-back-queue "Design Front Middle Back Queue")
-
-## [1669. Merge In Between Linked Lists (Medium)](https://leetcode.com/problems/merge-in-between-linked-lists "合并两个链表")
-
-<p>You are given two linked lists: <code>list1</code> and <code>list2</code> of sizes <code>n</code> and <code>m</code> respectively.</p>
-
-<p>Remove <code>list1</code>&#39;s nodes from the <code>a<sup>th</sup></code> node to the <code>b<sup>th</sup></code> node, and put <code>list2</code> in their place.</p>
-
-<p>The blue edges and nodes in the following figure indicate the result:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/fig1.png" style="height: 130px; width: 504px;" />
-<p><em>Build the result list and return its head.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/merge_linked_list_ex1.png" style="width: 406px; height: 140px;" />
-<pre>
-<strong>Input:</strong> list1 = [0,1,2,3,4,5], a = 3, b = 4, list2 = [1000000,1000001,1000002]
-<strong>Output:</strong> [0,1,2,1000000,1000001,1000002,5]
-<strong>Explanation:</strong> We remove the nodes 3 and 4 and put the entire list2 in their place. The blue edges and nodes in the above figure indicate the result.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/merge_linked_list_ex2.png" style="width: 463px; height: 140px;" />
-<pre>
-<strong>Input:</strong> list1 = [0,1,2,3,4,5,6], a = 2, b = 5, list2 = [1000000,1000001,1000002,1000003,1000004]
-<strong>Output:</strong> [0,1,1000000,1000001,1000002,1000003,1000004,6]
-<strong>Explanation:</strong> The blue edges and nodes in the above figure indicate the result.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= list1.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= a &lt;= b &lt; list1.length - 1</code></li>
-	<li><code>1 &lt;= list2.length &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check which edges need to be changed.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let the next node of the (a-1)th node of list1 be the 0-th node in list 2.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Let the next node of the last node of list2 be the (b+1)-th node in list 1.
-</details>
diff --git a/problems/merge-intervals/README.md b/problems/merge-intervals/README.md
deleted file mode 100644
index 9a94b715c..000000000
--- a/problems/merge-intervals/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../jump-game "Jump Game")
-　　　　　　　　　　　　　　　　
-[Next >](../insert-interval "Insert Interval")
-
-## [56. Merge Intervals (Medium)](https://leetcode.com/problems/merge-intervals "合并区间")
-
-<p>Given an array&nbsp;of <code>intervals</code>&nbsp;where <code>intervals[i] = [start<sub>i</sub>, end<sub>i</sub>]</code>, merge all overlapping intervals, and return <em>an array of the non-overlapping intervals that cover all the intervals in the input</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,3],[2,6],[8,10],[15,18]]
-<strong>Output:</strong> [[1,6],[8,10],[15,18]]
-<strong>Explanation:</strong> Since intervals [1,3] and [2,6] overlaps, merge them into [1,6].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,4],[4,5]]
-<strong>Output:</strong> [[1,5]]
-<strong>Explanation:</strong> Intervals [1,4] and [4,5] are considered overlapping.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= intervals.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>intervals[i].length == 2</code></li>
-	<li><code>0 &lt;= start<sub>i</sub> &lt;= end<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Insert Interval](../insert-interval) (Medium)
-  1. [Meeting Rooms](../meeting-rooms) (Easy)
-  1. [Meeting Rooms II](../meeting-rooms-ii) (Medium)
-  1. [Teemo Attacking](../teemo-attacking) (Easy)
-  1. [Add Bold Tag in String](../add-bold-tag-in-string) (Medium)
-  1. [Range Module](../range-module) (Hard)
-  1. [Employee Free Time](../employee-free-time) (Hard)
-  1. [Partition Labels](../partition-labels) (Medium)
-  1. [Interval List Intersections](../interval-list-intersections) (Medium)
-  1. [Amount of New Area Painted Each Day](../amount-of-new-area-painted-each-day) (Hard)
diff --git a/problems/merge-intervals/merge_intervals.go b/problems/merge-intervals/merge_intervals.go
deleted file mode 100644
index 21a487b4b..000000000
--- a/problems/merge-intervals/merge_intervals.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem56
diff --git a/problems/merge-intervals/merge_intervals_test.go b/problems/merge-intervals/merge_intervals_test.go
deleted file mode 100644
index 21a487b4b..000000000
--- a/problems/merge-intervals/merge_intervals_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem56
diff --git a/problems/merge-k-sorted-lists/README.md b/problems/merge-k-sorted-lists/README.md
deleted file mode 100644
index 9f1521f9e..000000000
--- a/problems/merge-k-sorted-lists/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../generate-parentheses "Generate Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../swap-nodes-in-pairs "Swap Nodes in Pairs")
-
-## [23. Merge k Sorted Lists (Hard)](https://leetcode.com/problems/merge-k-sorted-lists "合并K个升序链表")
-
-<p>You are given an array of <code>k</code> linked-lists <code>lists</code>, each linked-list is sorted in ascending order.</p>
-
-<p><em>Merge all the linked-lists into one sorted linked-list and return it.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> lists = [[1,4,5],[1,3,4],[2,6]]
-<strong>Output:</strong> [1,1,2,3,4,4,5,6]
-<strong>Explanation:</strong> The linked-lists are:
-[
-  1-&gt;4-&gt;5,
-  1-&gt;3-&gt;4,
-  2-&gt;6
-]
-merging them into one sorted list:
-1-&gt;1-&gt;2-&gt;3-&gt;4-&gt;4-&gt;5-&gt;6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> lists = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> lists = [[]]
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>k == lists.length</code></li>
-	<li><code>0 &lt;= k &lt;= 10^4</code></li>
-	<li><code>0 &lt;= lists[i].length &lt;= 500</code></li>
-	<li><code>-10^4 &lt;= lists[i][j] &lt;= 10^4</code></li>
-	<li><code>lists[i]</code> is sorted in <strong>ascending order</strong>.</li>
-	<li>The sum of <code>lists[i].length</code> won&#39;t exceed <code>10^4</code>.</li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Merge Sort](../../tag/merge-sort/README.md)]
-
-### Similar Questions
-  1. [Merge Two Sorted Lists](../merge-two-sorted-lists) (Easy)
-  1. [Ugly Number II](../ugly-number-ii) (Medium)
diff --git a/problems/merge-k-sorted-lists/merge_k_sorted_lists.go b/problems/merge-k-sorted-lists/merge_k_sorted_lists.go
deleted file mode 100644
index e702a73d7..000000000
--- a/problems/merge-k-sorted-lists/merge_k_sorted_lists.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package problem23
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func mergeKLists(lists []*ListNode) *ListNode {
-	var ans *ListNode
-	for _, l := range lists {
-		ans = mergeTwoLists(ans, l)
-	}
-	return ans
-}
-
-func mergeTwoLists(l1 *ListNode, l2 *ListNode) *ListNode {
-	if l1 == nil {
-		return l2
-	} else if l2 == nil {
-		return l1
-	}
-	if l1.Val > l2.Val {
-		l1, l2 = l2, l1
-	}
-	l1.Next = mergeTwoLists(l1.Next, l2)
-	return l1
-}
diff --git a/problems/merge-k-sorted-lists/merge_k_sorted_lists_test.go b/problems/merge-k-sorted-lists/merge_k_sorted_lists_test.go
deleted file mode 100644
index ebf91ea91..000000000
--- a/problems/merge-k-sorted-lists/merge_k_sorted_lists_test.go
+++ /dev/null
@@ -1,51 +0,0 @@
-package problem23
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   [][]int
-	want []int
-}
-
-func TestMergeKLists(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{1, 4, 5},
-				{1, 3, 4},
-				{2, 6},
-			},
-			want: []int{1, 1, 2, 3, 4, 4, 5, 6},
-		},
-		{
-			in: [][]int{
-				{2},
-				{},
-				{-1},
-			},
-			want: []int{-1, 2},
-		},
-		{
-			in: [][]int{
-				{},
-				{},
-			},
-			want: nil,
-		},
-	}
-	for _, tt := range tests {
-		lists := make([]*ListNode, len(tt.in))
-		for i, v := range tt.in {
-			lists[i] = kit.SliceInt2ListNode(v)
-		}
-		got := kit.ListNode2SliceInt(mergeKLists(lists))
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/merge-sorted-array/README.md b/problems/merge-sorted-array/README.md
deleted file mode 100644
index 8c50685d3..000000000
--- a/problems/merge-sorted-array/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../scramble-string "Scramble String")
-　　　　　　　　　　　　　　　　
-[Next >](../gray-code "Gray Code")
-
-## [88. Merge Sorted Array (Easy)](https://leetcode.com/problems/merge-sorted-array "合并两个有序数组")
-
-<p>You are given two integer arrays <code>nums1</code> and <code>nums2</code>, sorted in <strong>non-decreasing order</strong>, and two integers <code>m</code> and <code>n</code>, representing the number of elements in <code>nums1</code> and <code>nums2</code> respectively.</p>
-
-<p><strong>Merge</strong> <code>nums1</code> and <code>nums2</code> into a single array sorted in <strong>non-decreasing order</strong>.</p>
-
-<p>The final sorted array should not be returned by the function, but instead be <em>stored inside the array </em><code>nums1</code>. To accommodate this, <code>nums1</code> has a length of <code>m + n</code>, where the first <code>m</code> elements denote the elements that should be merged, and the last <code>n</code> elements are set to <code>0</code> and should be ignored. <code>nums2</code> has a length of <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3
-<strong>Output:</strong> [1,2,2,3,5,6]
-<strong>Explanation:</strong> The arrays we are merging are [1,2,3] and [2,5,6].
-The result of the merge is [<u>1</u>,<u>2</u>,2,<u>3</u>,5,6] with the underlined elements coming from nums1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1], m = 1, nums2 = [], n = 0
-<strong>Output:</strong> [1]
-<strong>Explanation:</strong> The arrays we are merging are [1] and [].
-The result of the merge is [1].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [0], m = 0, nums2 = [1], n = 1
-<strong>Output:</strong> [1]
-<strong>Explanation:</strong> The arrays we are merging are [] and [1].
-The result of the merge is [1].
-Note that because m = 0, there are no elements in nums1. The 0 is only there to ensure the merge result can fit in nums1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>nums1.length == m + n</code></li>
-	<li><code>nums2.length == n</code></li>
-	<li><code>0 &lt;= m, n &lt;= 200</code></li>
-	<li><code>1 &lt;= m + n &lt;= 200</code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums1[i], nums2[j] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up: </strong>Can you come up with an algorithm that runs in <code>O(m + n)</code> time?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Merge Two Sorted Lists](../merge-two-sorted-lists) (Easy)
-  1. [Squares of a Sorted Array](../squares-of-a-sorted-array) (Easy)
-  1. [Interval List Intersections](../interval-list-intersections) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can easily solve this problem if you simply think about two elements at a time rather than two arrays. We know that each of the individual arrays is sorted. What we don't know is how they will intertwine. Can we take a local decision and arrive at an optimal solution?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you simply consider one element each at a time from the two arrays and make a decision and proceed accordingly, you will arrive at the optimal solution.
-</details>
diff --git a/problems/merge-sorted-array/merge_sorted_array.go b/problems/merge-sorted-array/merge_sorted_array.go
deleted file mode 100644
index 05b2e9970..000000000
--- a/problems/merge-sorted-array/merge_sorted_array.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem88
-
-func merge(nums1 []int, m int, nums2 []int, n int) {
-	copy(nums1[n:], nums1)
-	cur, i, j := 0, n, 0
-	for j < n {
-		if i < m+n && nums1[i] < nums2[j] {
-			nums1[cur], i = nums1[i], i+1
-		} else {
-			nums1[cur], j = nums2[j], j+1
-		}
-		cur++
-	}
-}
diff --git a/problems/merge-sorted-array/merge_sorted_array_test.go b/problems/merge-sorted-array/merge_sorted_array_test.go
deleted file mode 100644
index 95dd0667d..000000000
--- a/problems/merge-sorted-array/merge_sorted_array_test.go
+++ /dev/null
@@ -1,46 +0,0 @@
-package problem88
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	nums1 []int
-	m     int
-	nums2 []int
-	n     int
-	want  []int
-}
-
-func TestMerge(t *testing.T) {
-	tests := [...]testType{
-		{
-			nums1: []int{1, 2, 3, 0, 0, 0},
-			m:     3,
-			nums2: []int{2, 5, 6},
-			n:     3,
-			want:  []int{1, 2, 2, 3, 5, 6},
-		},
-		{
-			nums1: []int{-9, -6, -3, 0, 0, 0},
-			m:     3,
-			nums2: []int{-7, -5, -3},
-			n:     3,
-			want:  []int{-9, -7, -6, -5, -3, -3},
-		},
-		{
-			nums1: []int{1, 2, 4, 5, 6, 0},
-			m:     5,
-			nums2: []int{3},
-			n:     1,
-			want:  []int{1, 2, 3, 4, 5, 6},
-		},
-	}
-	for _, tt := range tests {
-		merge(tt.nums1, tt.m, tt.nums2, tt.n)
-		if !reflect.DeepEqual(tt.nums1, tt.want) {
-			t.Fatalf("in: %v %v %v %v, got: %v, want: %v", tt.nums1, tt.m, tt.nums2, tt.n, tt.nums1, tt.want)
-		}
-	}
-}
diff --git a/problems/merge-strings-alternately/README.md b/problems/merge-strings-alternately/README.md
deleted file mode 100644
index 27cb88935..000000000
--- a/problems/merge-strings-alternately/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-subtasks-that-did-not-execute "Find the Subtasks That Did Not Execute")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-operations-to-move-all-balls-to-each-box "Minimum Number of Operations to Move All Balls to Each Box")
-
-## [1768. Merge Strings Alternately (Easy)](https://leetcode.com/problems/merge-strings-alternately "交替合并字符串")
-
-<p>You are given two strings <code>word1</code> and <code>word2</code>. Merge the strings by adding letters in alternating order, starting with <code>word1</code>. If a string is longer than the other, append the additional letters onto the end of the merged string.</p>
-
-<p>Return <em>the merged string.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;abc&quot;, word2 = &quot;pqr&quot;
-<strong>Output:</strong> &quot;apbqcr&quot;
-<strong>Explanation:</strong>&nbsp;The merged string will be merged as so:
-word1:  a   b   c
-word2:    p   q   r
-merged: a p b q c r
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;ab&quot;, word2 = &quot;pqrs&quot;
-<strong>Output:</strong> &quot;apbqrs&quot;
-<strong>Explanation:</strong>&nbsp;Notice that as word2 is longer, &quot;rs&quot; is appended to the end.
-word1:  a   b 
-word2:    p   q   r   s
-merged: a p b q   r   s
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word1 = &quot;abcd&quot;, word2 = &quot;pq&quot;
-<strong>Output:</strong> &quot;apbqcd&quot;
-<strong>Explanation:</strong>&nbsp;Notice that as word1 is longer, &quot;cd&quot; is appended to the end.
-word1:  a   b   c   d
-word2:    p   q 
-merged: a p b q c   d
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word1.length, word2.length &lt;= 100</code></li>
-	<li><code>word1</code> and <code>word2</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Zigzag Iterator](../zigzag-iterator) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use two pointers, one pointer for each string. Alternately choose the character from each pointer, and move the pointer upwards.
-</details>
diff --git a/problems/merge-triplets-to-form-target-triplet/README.md b/problems/merge-triplets-to-form-target-triplet/README.md
deleted file mode 100644
index cc1c8f67d..000000000
--- a/problems/merge-triplets-to-form-target-triplet/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-removable-characters "Maximum Number of Removable Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../the-earliest-and-latest-rounds-where-players-compete "The Earliest and Latest Rounds Where Players Compete")
-
-## [1899. Merge Triplets to Form Target Triplet (Medium)](https://leetcode.com/problems/merge-triplets-to-form-target-triplet "合并若干三元组以形成目标三元组")
-
-<p>A <strong>triplet</strong> is an array of three integers. You are given a 2D integer array <code>triplets</code>, where <code>triplets[i] = [a<sub>i</sub>, b<sub>i</sub>, c<sub>i</sub>]</code> describes the <code>i<sup>th</sup></code> <strong>triplet</strong>. You are also given an integer array <code>target = [x, y, z]</code> that describes the <strong>triplet</strong> you want to obtain.</p>
-
-<p>To obtain <code>target</code>, you may apply the following operation on <code>triplets</code> <strong>any number</strong> of times (possibly <strong>zero</strong>):</p>
-
-<ul>
-	<li>Choose two indices (<strong>0-indexed</strong>) <code>i</code> and <code>j</code> (<code>i != j</code>) and <strong>update</strong> <code>triplets[j]</code> to become <code>[max(a<sub>i</sub>, a<sub>j</sub>), max(b<sub>i</sub>, b<sub>j</sub>), max(c<sub>i</sub>, c<sub>j</sub>)]</code>.
-	<ul>
-		<li>For example, if <code>triplets[i] = [2, 5, 3]</code> and <code>triplets[j] = [1, 7, 5]</code>, <code>triplets[j]</code> will be updated to <code>[max(2, 1), max(5, 7), max(3, 5)] = [2, 7, 5]</code>.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <code>true</code> <em>if it is possible to obtain the </em><code>target</code><em> <strong>triplet</strong> </em><code>[x, y, z]</code><em> as an<strong> element</strong> of </em><code>triplets</code><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> triplets = [[2,5,3],[1,8,4],[1,7,5]], target = [2,7,5]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Perform the following operations:
-- Choose the first and last triplets [<u>[2,5,3]</u>,[1,8,4],<u>[1,7,5]</u>]. Update the last triplet to be [max(2,1), max(5,7), max(3,5)] = [2,7,5]. triplets = [[2,5,3],[1,8,4],<u>[2,7,5]</u>]
-The target triplet [2,7,5] is now an element of triplets.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> triplets = [[3,4,5],[4,5,6]], target = [3,2,5]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to have [3,2,5] as an element because there is no 2 in any of the triplets.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> triplets = [[2,5,3],[2,3,4],[1,2,5],[5,2,3]], target = [5,5,5]
-<strong>Output:</strong> true
-<strong>Explanation: </strong>Perform the following operations:
-- Choose the first and third triplets [<u>[2,5,3]</u>,[2,3,4],<u>[1,2,5]</u>,[5,2,3]]. Update the third triplet to be [max(2,1), max(5,2), max(3,5)] = [2,5,5]. triplets = [[2,5,3],[2,3,4],<u>[2,5,5]</u>,[5,2,3]].
-- Choose the third and fourth triplets [[2,5,3],[2,3,4],<u>[2,5,5]</u>,<u>[5,2,3]</u>]. Update the fourth triplet to be [max(2,5), max(5,2), max(5,3)] = [5,5,5]. triplets = [[2,5,3],[2,3,4],[2,5,5],<u>[5,5,5]</u>].
-The target triplet [5,5,5] is now an element of triplets.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= triplets.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>triplets[i].length == target.length == 3</code></li>
-	<li><code>1 &lt;= a<sub>i</sub>, b<sub>i</sub>, c<sub>i</sub>, x, y, z &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Which triplets do you actually care about?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What property of max can you use to solve the problem?
-</details>
diff --git a/problems/merge-two-binary-trees/README.md b/problems/merge-two-binary-trees/README.md
deleted file mode 100644
index 330e3191b..000000000
--- a/problems/merge-two-binary-trees/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-bold-tag-in-string "Add Bold Tag in String")
-　　　　　　　　　　　　　　　　
-[Next >](../students-report-by-geography "Students Report By Geography")
-
-## [617. Merge Two Binary Trees (Easy)](https://leetcode.com/problems/merge-two-binary-trees "合并二叉树")
-
-<p>You are given two binary trees <code>root1</code> and <code>root2</code>.</p>
-
-<p>Imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not. You need to merge the two trees into a new binary tree. The merge rule is that if two nodes overlap, then sum node values up as the new value of the merged node. Otherwise, the NOT null node will be used as the node of the new tree.</p>
-
-<p>Return <em>the merged tree</em>.</p>
-
-<p><strong>Note:</strong> The merging process must start from the root nodes of both trees.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/05/merge.jpg" style="width: 600px; height: 163px;" />
-<pre>
-<strong>Input:</strong> root1 = [1,3,2,5], root2 = [2,1,3,null,4,null,7]
-<strong>Output:</strong> [3,4,5,5,4,null,7]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root1 = [1], root2 = [1,2]
-<strong>Output:</strong> [2,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in both trees is in the range <code>[0, 2000]</code>.</li>
-	<li><code>-10<sup>4</sup> &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/merge-two-binary-trees/merge_two_binary_trees.go b/problems/merge-two-binary-trees/merge_two_binary_trees.go
deleted file mode 100644
index f82bf9106..000000000
--- a/problems/merge-two-binary-trees/merge_two_binary_trees.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem617
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func mergeTrees(t1 *TreeNode, t2 *TreeNode) *TreeNode {
-	if t1 == nil {
-		return t2
-	}
-	if t2 == nil {
-		return t1
-	}
-	t1.Val += t2.Val
-	t1.Left = mergeTrees(t1.Left, t2.Left)
-	t1.Right = mergeTrees(t1.Right, t2.Right)
-	return t1
-}
diff --git a/problems/merge-two-binary-trees/merge_two_binary_trees_test.go b/problems/merge-two-binary-trees/merge_two_binary_trees_test.go
deleted file mode 100644
index 9da149f2e..000000000
--- a/problems/merge-two-binary-trees/merge_two_binary_trees_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem617
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	t1   []int
-	t2   []int
-	want []int
-}
-
-func TestMergeTrees(t *testing.T) {
-	tests := [...]testType{
-		{
-			t1:   []int{1, 3, 2, 5},
-			t2:   []int{2, 1, 3, kit.NULL, 4, kit.NULL, 7},
-			want: []int{3, 4, 5, 5, 4, kit.NULL, 7},
-		},
-	}
-	for _, tt := range tests {
-		t3 := mergeTrees(kit.SliceInt2TreeNode(tt.t1), kit.SliceInt2TreeNode(tt.t2))
-		got := kit.TreeNode2SliceInt(t3)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.t1, tt.t2, got, tt.want)
-		}
-	}
-}
diff --git a/problems/merge-two-sorted-lists/README.md b/problems/merge-two-sorted-lists/README.md
deleted file mode 100644
index 893f84595..000000000
--- a/problems/merge-two-sorted-lists/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-parentheses "Valid Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../generate-parentheses "Generate Parentheses")
-
-## [21. Merge Two Sorted Lists (Easy)](https://leetcode.com/problems/merge-two-sorted-lists "合并两个有序链表")
-
-<p>You are given the heads of two sorted linked lists <code>list1</code> and <code>list2</code>.</p>
-
-<p>Merge the two lists in a one <strong>sorted</strong> list. The list should be made by splicing together the nodes of the first two lists.</p>
-
-<p>Return <em>the head of the merged linked list</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/merge_ex1.jpg" style="width: 662px; height: 302px;" />
-<pre>
-<strong>Input:</strong> list1 = [1,2,4], list2 = [1,3,4]
-<strong>Output:</strong> [1,1,2,3,4,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> list1 = [], list2 = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> list1 = [], list2 = [0]
-<strong>Output:</strong> [0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in both lists is in the range <code>[0, 50]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-	<li>Both <code>list1</code> and <code>list2</code> are sorted in <strong>non-decreasing</strong> order.</li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Merge k Sorted Lists](../merge-k-sorted-lists) (Hard)
-  1. [Merge Sorted Array](../merge-sorted-array) (Easy)
-  1. [Sort List](../sort-list) (Medium)
-  1. [Shortest Word Distance II](../shortest-word-distance-ii) (Medium)
diff --git a/problems/merge-two-sorted-lists/merge_two_sorted_lists.go b/problems/merge-two-sorted-lists/merge_two_sorted_lists.go
deleted file mode 100644
index 2701fa1ee..000000000
--- a/problems/merge-two-sorted-lists/merge_two_sorted_lists.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package problem21
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func mergeTwoLists(l1 *ListNode, l2 *ListNode) *ListNode {
-	if l1 == nil {
-		return l2
-	} else if l2 == nil {
-		return l1
-	}
-	if l1.Val > l2.Val {
-		l1, l2 = l2, l1
-	}
-	l1.Next = mergeTwoLists(l1.Next, l2)
-	return l1
-}
diff --git a/problems/merge-two-sorted-lists/merge_two_sorted_lists_test.go b/problems/merge-two-sorted-lists/merge_two_sorted_lists_test.go
deleted file mode 100644
index 125d12f2f..000000000
--- a/problems/merge-two-sorted-lists/merge_two_sorted_lists_test.go
+++ /dev/null
@@ -1,52 +0,0 @@
-package problem21
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	l1   []int
-	l2   []int
-	want []int
-}
-
-func TestMergeTwoLists(t *testing.T) {
-	tests := [...]testType{
-		{
-			l1:   []int{1, 2, 4},
-			l2:   []int{1, 3, 4},
-			want: []int{1, 1, 2, 3, 4, 4},
-		},
-		{
-			l1:   nil,
-			l2:   nil,
-			want: nil,
-		},
-		{
-			l1:   nil,
-			l2:   []int{1, 2, 3},
-			want: []int{1, 2, 3},
-		},
-		{
-			l1:   []int{1, 2, 3},
-			l2:   nil,
-			want: []int{1, 2, 3},
-		},
-		{
-			l1:   []int{1, 2, 3, 8, 16},
-			l2:   []int{1, 2, 3, 10, 12, 24},
-			want: []int{1, 1, 2, 2, 3, 3, 8, 10, 12, 16, 24},
-		},
-	}
-	for _, tt := range tests {
-		l1 := kit.SliceInt2ListNode(tt.l1)
-		l2 := kit.SliceInt2ListNode(tt.l2)
-		got := kit.ListNode2SliceInt(mergeTwoLists(l1, l2))
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.l1, tt.l2, got, tt.want)
-		}
-	}
-}
diff --git a/problems/middle-of-the-linked-list/README.md b/problems/middle-of-the-linked-list/README.md
deleted file mode 100644
index e54ef54e1..000000000
--- a/problems/middle-of-the-linked-list/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../koko-eating-bananas "Koko Eating Bananas")
-　　　　　　　　　　　　　　　　
-[Next >](../stone-game "Stone Game")
-
-## [876. Middle of the Linked List (Easy)](https://leetcode.com/problems/middle-of-the-linked-list "链表的中间结点")
-
-<p>Given the <code>head</code> of a singly linked list, return <em>the middle node of the linked list</em>.</p>
-
-<p>If there are two middle nodes, return <strong>the second middle</strong> node.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-midlist1.jpg" style="width: 544px; height: 65px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5]
-<strong>Output:</strong> [3,4,5]
-<strong>Explanation:</strong> The middle node of the list is node 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-midlist2.jpg" style="width: 664px; height: 65px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5,6]
-<strong>Output:</strong> [4,5,6]
-<strong>Explanation:</strong> Since the list has two middle nodes with values 3 and 4, we return the second one.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[1, 100]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
diff --git a/problems/middle-of-the-linked-list/middle_of_the_linked_list.go b/problems/middle-of-the-linked-list/middle_of_the_linked_list.go
deleted file mode 100644
index 0eee438de..000000000
--- a/problems/middle-of-the-linked-list/middle_of_the_linked_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem876
diff --git a/problems/middle-of-the-linked-list/middle_of_the_linked_list_test.go b/problems/middle-of-the-linked-list/middle_of_the_linked_list_test.go
deleted file mode 100644
index 0eee438de..000000000
--- a/problems/middle-of-the-linked-list/middle_of_the_linked_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem876
diff --git a/problems/min-cost-climbing-stairs/README.md b/problems/min-cost-climbing-stairs/README.md
deleted file mode 100644
index 9e47493b8..000000000
--- a/problems/min-cost-climbing-stairs/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../prefix-and-suffix-search "Prefix and Suffix Search")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-number-at-least-twice-of-others "Largest Number At Least Twice of Others")
-
-## [746. Min Cost Climbing Stairs (Easy)](https://leetcode.com/problems/min-cost-climbing-stairs "使用最小花费爬楼梯")
-
-<p>You are given an integer array <code>cost</code> where <code>cost[i]</code> is the cost of <code>i<sup>th</sup></code> step on a staircase. Once you pay the cost, you can either climb one or two steps.</p>
-
-<p>You can either start from the step with index <code>0</code>, or the step with index <code>1</code>.</p>
-
-<p>Return <em>the minimum cost to reach the top of the floor</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> cost = [10,<u>15</u>,20]
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> You will start at index 1.
-- Pay 15 and climb two steps to reach the top.
-The total cost is 15.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> cost = [<u>1</u>,100,<u>1</u>,1,<u>1</u>,100,<u>1</u>,<u>1</u>,100,<u>1</u>]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> You will start at index 0.
-- Pay 1 and climb two steps to reach index 2.
-- Pay 1 and climb two steps to reach index 4.
-- Pay 1 and climb two steps to reach index 6.
-- Pay 1 and climb one step to reach index 7.
-- Pay 1 and climb two steps to reach index 9.
-- Pay 1 and climb one step to reach the top.
-The total cost is 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= cost.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= cost[i] &lt;= 999</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Climbing Stairs](../climbing-stairs) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Say f[i] is the final cost to climb to the top from step i.  Then f[i] = cost[i] + min(f[i+1], f[i+2]).
-</details>
diff --git a/problems/min-cost-climbing-stairs/min_cost_climbing_stairs.go b/problems/min-cost-climbing-stairs/min_cost_climbing_stairs.go
deleted file mode 100644
index fed2a2177..000000000
--- a/problems/min-cost-climbing-stairs/min_cost_climbing_stairs.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem746
-
-func minCostClimbingStairs(cost []int) int {
-	f1, f2, l := 0, 0, len(cost)-1
-	for i := l; i >= 0; i-- {
-		f0 := f1
-		if f2 < f1 {
-			f0 = f2
-		}
-		f0 += cost[i]
-		f1, f2 = f0, f1
-	}
-	if f1 <= f2 {
-		return f1
-	}
-	return f2
-}
diff --git a/problems/min-cost-climbing-stairs/min_cost_climbing_stairs_test.go b/problems/min-cost-climbing-stairs/min_cost_climbing_stairs_test.go
deleted file mode 100644
index 37d4e96a5..000000000
--- a/problems/min-cost-climbing-stairs/min_cost_climbing_stairs_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem746
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMinCostClimbingStairs(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{10, 15, 20},
-			want: 15,
-		},
-		{
-			in:   []int{1, 100, 1, 1, 1, 100, 1, 1, 100, 1},
-			want: 6,
-		},
-	}
-	for _, tt := range tests {
-		got := minCostClimbingStairs(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/min-cost-to-connect-all-points/README.md b/problems/min-cost-to-connect-all-points/README.md
deleted file mode 100644
index 7cb2c19ad..000000000
--- a/problems/min-cost-to-connect-all-points/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-unhappy-friends "Count Unhappy Friends")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-string-is-transformable-with-substring-sort-operations "Check If String Is Transformable With Substring Sort Operations")
-
-## [1584. Min Cost to Connect All Points (Medium)](https://leetcode.com/problems/min-cost-to-connect-all-points "连接所有点的最小费用")
-
-<p>You are given an array <code>points</code> representing integer coordinates of some points on a 2D-plane, where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>.</p>
-
-<p>The cost of connecting two points <code>[x<sub>i</sub>, y<sub>i</sub>]</code> and <code>[x<sub>j</sub>, y<sub>j</sub>]</code> is the <strong>manhattan distance</strong> between them: <code>|x<sub>i</sub> - x<sub>j</sub>| + |y<sub>i</sub> - y<sub>j</sub>|</code>, where <code>|val|</code> denotes the absolute value of <code>val</code>.</p>
-
-<p>Return <em>the minimum cost to make all points connected.</em> All points are connected if there is <strong>exactly one</strong> simple path between any two points.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/26/d.png" style="width: 214px; height: 268px;" />
-<pre>
-<strong>Input:</strong> points = [[0,0],[2,2],[3,10],[5,2],[7,0]]
-<strong>Output:</strong> 20
-<strong>Explanation:</strong> 
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/26/c.png" style="width: 214px; height: 268px;" />
-We can connect the points as shown above to get the minimum cost of 20.
-Notice that there is a unique path between every pair of points.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[3,12],[-2,5],[-4,1]]
-<strong>Output:</strong> 18
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= points.length &lt;= 1000</code></li>
-	<li><code>-10<sup>6</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>6</sup></code></li>
-	<li>All pairs <code>(x<sub>i</sub>, y<sub>i</sub>)</code> are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Minimum Spanning Tree](../../tag/minimum-spanning-tree/README.md)]
-
-### Similar Questions
-  1. [Minimum Number of Lines to Cover Points](../minimum-number-of-lines-to-cover-points) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Connect each pair of points with a weighted edge, the weight being the manhattan distance between those points.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The problem is now the cost of minimum spanning tree in graph with above edges.
-</details>
diff --git a/problems/min-stack/README.md b/problems/min-stack/README.md
deleted file mode 100644
index 13567cb2e..000000000
--- a/problems/min-stack/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-minimum-in-rotated-sorted-array-ii "Find Minimum in Rotated Sorted Array II")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-upside-down "Binary Tree Upside Down")
-
-## [155. Min Stack (Easy)](https://leetcode.com/problems/min-stack "最小栈")
-
-<p>Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.</p>
-
-<p>Implement the <code>MinStack</code> class:</p>
-
-<ul>
-	<li><code>MinStack()</code> initializes the stack object.</li>
-	<li><code>void push(int val)</code> pushes the element <code>val</code> onto the stack.</li>
-	<li><code>void pop()</code> removes the element on the top of the stack.</li>
-	<li><code>int top()</code> gets the top element of the stack.</li>
-	<li><code>int getMin()</code> retrieves the minimum element in the stack.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MinStack&quot;,&quot;push&quot;,&quot;push&quot;,&quot;push&quot;,&quot;getMin&quot;,&quot;pop&quot;,&quot;top&quot;,&quot;getMin&quot;]
-[[],[-2],[0],[-3],[],[],[],[]]
-
-<strong>Output</strong>
-[null,null,null,null,-3,null,0,-2]
-
-<strong>Explanation</strong>
-MinStack minStack = new MinStack();
-minStack.push(-2);
-minStack.push(0);
-minStack.push(-3);
-minStack.getMin(); // return -3
-minStack.pop();
-minStack.top();    // return 0
-minStack.getMin(); // return -2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= val &lt;= 2<sup>31</sup> - 1</code></li>
-	<li>Methods <code>pop</code>, <code>top</code> and <code>getMin</code> operations will always be called on <strong>non-empty</strong> stacks.</li>
-	<li>At most <code>3 * 10<sup>4</sup></code> calls will be made to <code>push</code>, <code>pop</code>, <code>top</code>, and <code>getMin</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Similar Questions
-  1. [Sliding Window Maximum](../sliding-window-maximum) (Hard)
-  1. [Max Stack](../max-stack) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider each node in the stack having a minimum value. (Credits to @aakarshmadhavan)
-</details>
diff --git a/problems/min-stack/min_stack.go b/problems/min-stack/min_stack.go
deleted file mode 100644
index 2f699d078..000000000
--- a/problems/min-stack/min_stack.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem155
-
-type MinStack struct {
-	stack [][2]int
-}
-
-/** initialize your data structure here. */
-func Constructor() MinStack {
-	return MinStack{}
-}
-
-func (this *MinStack) Push(x int) {
-	min, l := x, len(this.stack)
-	if l > 0 && this.stack[l-1][1] < x {
-		min = this.stack[l-1][1]
-	}
-	this.stack = append(this.stack, [2]int{x, min})
-}
-
-func (this *MinStack) Pop() {
-	this.stack = this.stack[:len(this.stack)-1]
-}
-
-func (this *MinStack) Top() int {
-	return this.stack[len(this.stack)-1][0]
-}
-
-func (this *MinStack) GetMin() int {
-	return this.stack[len(this.stack)-1][1]
-}
-
-/**
- * Your MinStack object will be instantiated and called as such:
- * obj := Constructor();
- * obj.Push(x);
- * obj.Pop();
- * param_3 := obj.Top();
- * param_4 := obj.GetMin();
- */
diff --git a/problems/min-stack/min_stack_test.go b/problems/min-stack/min_stack_test.go
deleted file mode 100644
index 27d60ea1b..000000000
--- a/problems/min-stack/min_stack_test.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem155
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestMinStack(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{-2, 0, -3},
-			want: []int{-3, 0, -2},
-		},
-	}
-	for _, tt := range tests {
-		minStack, got := Constructor(), make([]int, 0)
-		for _, x := range tt.in {
-			minStack.Push(x)
-		}
-		got = append(got, minStack.GetMin())
-		minStack.Pop()
-		got = append(got, minStack.Top())
-		got = append(got, minStack.GetMin())
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/minesweeper/README.md b/problems/minesweeper/README.md
deleted file mode 100644
index 618c0715f..000000000
--- a/problems/minesweeper/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../random-pick-with-weight "Random Pick with Weight")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-absolute-difference-in-bst "Minimum Absolute Difference in BST")
-
-## [529. Minesweeper (Medium)](https://leetcode.com/problems/minesweeper "扫雷游戏")
-
-<p>Let&#39;s play the minesweeper game (<a href="https://en.wikipedia.org/wiki/Minesweeper_(video_game)" target="_blank">Wikipedia</a>, <a href="http://minesweeperonline.com" target="_blank">online game</a>)!</p>
-
-<p>You are given an <code>m x n</code> char matrix <code>board</code> representing the game board where:</p>
-
-<ul>
-	<li><code>&#39;M&#39;</code> represents an unrevealed mine,</li>
-	<li><code>&#39;E&#39;</code> represents an unrevealed empty square,</li>
-	<li><code>&#39;B&#39;</code> represents a revealed blank square that has no adjacent mines (i.e., above, below, left, right, and all 4 diagonals),</li>
-	<li>digit (<code>&#39;1&#39;</code> to <code>&#39;8&#39;</code>) represents how many mines are adjacent to this revealed square, and</li>
-	<li><code>&#39;X&#39;</code> represents a revealed mine.</li>
-</ul>
-
-<p>You are also given an integer array <code>click</code> where <code>click = [click<sub>r</sub>, click<sub>c</sub>]</code> represents the next click position among all the unrevealed squares (<code>&#39;M&#39;</code> or <code>&#39;E&#39;</code>).</p>
-
-<p>Return <em>the board after revealing this position according to the following rules</em>:</p>
-
-<ol>
-	<li>If a mine <code>&#39;M&#39;</code> is revealed, then the game is over. You should change it to <code>&#39;X&#39;</code>.</li>
-	<li>If an empty square <code>&#39;E&#39;</code> with no adjacent mines is revealed, then change it to a revealed blank <code>&#39;B&#39;</code> and all of its adjacent unrevealed squares should be revealed recursively.</li>
-	<li>If an empty square <code>&#39;E&#39;</code> with at least one adjacent mine is revealed, then change it to a digit (<code>&#39;1&#39;</code> to <code>&#39;8&#39;</code>) representing the number of adjacent mines.</li>
-	<li>Return the board when no more squares will be revealed.</li>
-</ol>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://assets.leetcode.com/uploads/2018/10/12/minesweeper_example_1.png" style="width: 500px; max-width: 400px; height: 269px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;E&quot;,&quot;E&quot;,&quot;E&quot;,&quot;E&quot;,&quot;E&quot;],[&quot;E&quot;,&quot;E&quot;,&quot;M&quot;,&quot;E&quot;,&quot;E&quot;],[&quot;E&quot;,&quot;E&quot;,&quot;E&quot;,&quot;E&quot;,&quot;E&quot;],[&quot;E&quot;,&quot;E&quot;,&quot;E&quot;,&quot;E&quot;,&quot;E&quot;]], click = [3,0]
-<strong>Output:</strong> [[&quot;B&quot;,&quot;1&quot;,&quot;E&quot;,&quot;1&quot;,&quot;B&quot;],[&quot;B&quot;,&quot;1&quot;,&quot;M&quot;,&quot;1&quot;,&quot;B&quot;],[&quot;B&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;B&quot;],[&quot;B&quot;,&quot;B&quot;,&quot;B&quot;,&quot;B&quot;,&quot;B&quot;]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img src="https://assets.leetcode.com/uploads/2018/10/12/minesweeper_example_2.png" style="width: 500px; max-width: 400px; height: 275px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;B&quot;,&quot;1&quot;,&quot;E&quot;,&quot;1&quot;,&quot;B&quot;],[&quot;B&quot;,&quot;1&quot;,&quot;M&quot;,&quot;1&quot;,&quot;B&quot;],[&quot;B&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;B&quot;],[&quot;B&quot;,&quot;B&quot;,&quot;B&quot;,&quot;B&quot;,&quot;B&quot;]], click = [1,2]
-<strong>Output:</strong> [[&quot;B&quot;,&quot;1&quot;,&quot;E&quot;,&quot;1&quot;,&quot;B&quot;],[&quot;B&quot;,&quot;1&quot;,&quot;X&quot;,&quot;1&quot;,&quot;B&quot;],[&quot;B&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;B&quot;],[&quot;B&quot;,&quot;B&quot;,&quot;B&quot;,&quot;B&quot;,&quot;B&quot;]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == board.length</code></li>
-	<li><code>n == board[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>board[i][j]</code> is either <code>&#39;M&#39;</code>, <code>&#39;E&#39;</code>, <code>&#39;B&#39;</code>, or a digit from <code>&#39;1&#39;</code> to <code>&#39;8&#39;</code>.</li>
-	<li><code>click.length == 2</code></li>
-	<li><code>0 &lt;= click<sub>r</sub> &lt; m</code></li>
-	<li><code>0 &lt;= click<sub>c</sub> &lt; n</code></li>
-	<li><code>board[click<sub>r</sub>][click<sub>c</sub>]</code> is either <code>&#39;M&#39;</code> or <code>&#39;E&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/minesweeper/minesweeper.go b/problems/minesweeper/minesweeper.go
deleted file mode 100644
index 30ba7e920..000000000
--- a/problems/minesweeper/minesweeper.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem529
diff --git a/problems/minesweeper/minesweeper_test.go b/problems/minesweeper/minesweeper_test.go
deleted file mode 100644
index 30ba7e920..000000000
--- a/problems/minesweeper/minesweeper_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem529
diff --git a/problems/mini-parser/README.md b/problems/mini-parser/README.md
deleted file mode 100644
index 2a2884145..000000000
--- a/problems/mini-parser/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shuffle-an-array "Shuffle an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../lexicographical-numbers "Lexicographical Numbers")
-
-## [385. Mini Parser (Medium)](https://leetcode.com/problems/mini-parser "迷你语法分析器")
-
-<p>Given a string s represents the serialization of a nested list, implement a parser to deserialize it and return <em>the deserialized</em> <code>NestedInteger</code>.</p>
-
-<p>Each element is either an integer or a list whose elements may also be integers or other lists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;324&quot;
-<strong>Output:</strong> 324
-<strong>Explanation:</strong> You should return a NestedInteger object which contains a single integer 324.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;[123,[456,[789]]]&quot;
-<strong>Output:</strong> [123,[456,[789]]]
-<strong>Explanation:</strong> Return a NestedInteger object containing a nested list with 2 elements:
-1. An integer containing value 123.
-2. A nested list containing two elements:
-    i.  An integer containing value 456.
-    ii. A nested list with one element:
-         a. An integer containing value 789
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of digits, square brackets <code>&quot;[]&quot;</code>, negative sign <code>&#39;-&#39;</code>, and commas <code>&#39;,&#39;</code>.</li>
-	<li><code>s</code> is the serialization of valid <code>NestedInteger</code>.</li>
-	<li>All the values in the input are in the range <code>[-10<sup>6</sup>, 10<sup>6</sup>]</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-
-### Similar Questions
-  1. [Flatten Nested List Iterator](../flatten-nested-list-iterator) (Medium)
-  1. [Ternary Expression Parser](../ternary-expression-parser) (Medium)
-  1. [Remove Comments](../remove-comments) (Medium)
diff --git a/problems/mini-parser/mini_parser.go b/problems/mini-parser/mini_parser.go
deleted file mode 100644
index 951cf942c..000000000
--- a/problems/mini-parser/mini_parser.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem385
diff --git a/problems/mini-parser/mini_parser_test.go b/problems/mini-parser/mini_parser_test.go
deleted file mode 100644
index 951cf942c..000000000
--- a/problems/mini-parser/mini_parser_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem385
diff --git a/problems/minimize-deviation-in-array/README.md b/problems/minimize-deviation-in-array/README.md
deleted file mode 100644
index 9b41e74d4..000000000
--- a/problems/minimize-deviation-in-array/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-moves-to-make-array-complementary "Minimum Moves to Make Array Complementary")
-　　　　　　　　　　　　　　　　
-[Next >](../lowest-common-ancestor-of-a-binary-tree-iv "Lowest Common Ancestor of a Binary Tree IV")
-
-## [1675. Minimize Deviation in Array (Hard)](https://leetcode.com/problems/minimize-deviation-in-array "数组的最小偏移量")
-
-<p>You are given an array <code>nums</code> of <code>n</code> positive integers.</p>
-
-<p>You can perform two types of operations on any element of the array any number of times:</p>
-
-<ul>
-	<li>If the element is <strong>even</strong>, <strong>divide</strong> it by <code>2</code>.
-	<ul>
-		<li>For example, if the array is <code>[1,2,3,4]</code>, then you can do this operation on the last element, and the array will be <code>[1,2,3,<u>2</u>].</code></li>
-	</ul>
-	</li>
-	<li>If the element is <strong>odd</strong>, <strong>multiply</strong> it by <code>2</code>.
-	<ul>
-		<li>For example, if the array is <code>[1,2,3,4]</code>, then you can do this operation on the first element, and the array will be <code>[<u>2</u>,2,3,4].</code></li>
-	</ul>
-	</li>
-</ul>
-
-<p>The <strong>deviation</strong> of the array is the <strong>maximum difference</strong> between any two elements in the array.</p>
-
-<p>Return <em>the <strong>minimum deviation</strong> the array can have after performing some number of operations.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You can transform the array to [1,2,3,<u>2</u>], then to [<u>2</u>,2,3,2], then the deviation will be 3 - 2 = 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,1,5,20,3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You can transform the array after two operations to [4,<u>2</u>,5,<u>5</u>,3], then the deviation will be 5 - 2 = 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,10,8]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup><span style="font-size: 10.8333px;">5</span></sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Assume you start with the minimum possible value for each number so you can only multiply a number by 2 till it reaches its maximum possible value.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If there is a better solution than the current one, then it must have either its maximum value less than the current maximum value, or the minimum value larger than the current minimum value.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Since that we only increase numbers (multiply them by 2), we cannot decrease the current maximum value, so we must multiply the current minimum number by 2.
-</details>
diff --git a/problems/minimize-hamming-distance-after-swap-operations/README.md b/problems/minimize-hamming-distance-after-swap-operations/README.md
deleted file mode 100644
index 9a9482090..000000000
--- a/problems/minimize-hamming-distance-after-swap-operations/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../swapping-nodes-in-a-linked-list "Swapping Nodes in a Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../find-minimum-time-to-finish-all-jobs "Find Minimum Time to Finish All Jobs")
-
-## [1722. Minimize Hamming Distance After Swap Operations (Medium)](https://leetcode.com/problems/minimize-hamming-distance-after-swap-operations "执行交换操作后的最小汉明距离")
-
-<p>You are given two integer arrays, <code>source</code> and <code>target</code>, both of length <code>n</code>. You are also given an array <code>allowedSwaps</code> where each <code>allowedSwaps[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that you are allowed to swap the elements at index <code>a<sub>i</sub></code> and index <code>b<sub>i</sub></code> <strong>(0-indexed)</strong> of array <code>source</code>. Note that you can swap elements at a specific pair of indices <strong>multiple</strong> times and in <strong>any</strong> order.</p>
-
-<p>The <strong>Hamming distance</strong> of two arrays of the same length, <code>source</code> and <code>target</code>, is the number of positions where the elements are different. Formally, it is the number of indices <code>i</code> for <code>0 &lt;= i &lt;= n-1</code> where <code>source[i] != target[i]</code> <strong>(0-indexed)</strong>.</p>
-
-<p>Return <em>the <strong>minimum Hamming distance</strong> of </em><code>source</code><em> and </em><code>target</code><em> after performing <strong>any</strong> amount of swap operations on array </em><code>source</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> source = [1,2,3,4], target = [2,1,4,5], allowedSwaps = [[0,1],[2,3]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> source can be transformed the following way:
-- Swap indices 0 and 1: source = [<u>2</u>,<u>1</u>,3,4]
-- Swap indices 2 and 3: source = [2,1,<u>4</u>,<u>3</u>]
-The Hamming distance of source and target is 1 as they differ in 1 position: index 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> source = [1,2,3,4], target = [1,3,2,4], allowedSwaps = []
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are no allowed swaps.
-The Hamming distance of source and target is 2 as they differ in 2 positions: index 1 and index 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> source = [5,1,2,4,3], target = [1,5,4,2,3], allowedSwaps = [[0,4],[4,2],[1,3],[1,4]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == source.length == target.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= source[i], target[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= allowedSwaps.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>allowedSwaps[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-
-### Similar Questions
-  1. [Smallest String With Swaps](../smallest-string-with-swaps) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The source array can be imagined as a graph where each index is a node and each allowedSwaps[i] is an edge.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Nodes within the same component can be freely swapped with each other.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For each component, find the number of common elements. The elements that are not in common will contribute to the total Hamming distance.
-</details>
diff --git a/problems/minimize-malware-spread-ii/README.md b/problems/minimize-malware-spread-ii/README.md
deleted file mode 100644
index 47e6e4f6d..000000000
--- a/problems/minimize-malware-spread-ii/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../three-equal-parts "Three Equal Parts")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-email-addresses "Unique Email Addresses")
-
-## [928. Minimize Malware Spread II (Hard)](https://leetcode.com/problems/minimize-malware-spread-ii "尽量减少恶意软件的传播 II")
-
-<p>You are given a network of <code>n</code> nodes represented as an <code>n x n</code> adjacency matrix <code>graph</code>, where the <code>i<sup>th</sup></code> node is directly connected to the <code>j<sup>th</sup></code> node if <code>graph[i][j] == 1</code>.</p>
-
-<p>Some nodes <code>initial</code> are initially infected by malware. Whenever two nodes are directly connected, and at least one of those two nodes is infected by malware, both nodes will be infected by malware. This spread of malware will continue until no more nodes can be infected in this manner.</p>
-
-<p>Suppose <code>M(initial)</code> is the final number of nodes infected with malware in the entire network after the spread of malware stops.</p>
-
-<p>We will remove <strong>exactly one node</strong> from <code>initial</code>, <strong>completely removing it and any connections from this node to any other node</strong>.</p>
-
-<p>Return the node that, if removed, would minimize <code>M(initial)</code>. If multiple nodes could be removed to minimize <code>M(initial)</code>, return such a node with <strong>the smallest index</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> graph = [[1,1,0],[1,1,0],[0,0,1]], initial = [0,1]
-<strong>Output:</strong> 0
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> graph = [[1,1,0],[1,1,1],[0,1,1]], initial = [0,1]
-<strong>Output:</strong> 1
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> graph = [[1,1,0,0],[1,1,1,0],[0,1,1,1],[0,0,1,1]], initial = [0,1]
-<strong>Output:</strong> 1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == graph.length</code></li>
-	<li><code>n == graph[i].length</code></li>
-	<li><code>2 &lt;= n &lt;= 300</code></li>
-	<li><code>graph[i][j]</code> is <code>0</code> or <code>1</code>.</li>
-	<li><code>graph[i][j] == graph[j][i]</code></li>
-	<li><code>graph[i][i] == 1</code></li>
-	<li><code>1 &lt;= initial.length &lt;&nbsp;n</code></li>
-	<li><code>0 &lt;= initial[i] &lt;= n - 1</code></li>
-	<li>All the integers in <code>initial</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/minimize-malware-spread-ii/minimize_malware_spread_ii.go b/problems/minimize-malware-spread-ii/minimize_malware_spread_ii.go
deleted file mode 100644
index 46b69ff9b..000000000
--- a/problems/minimize-malware-spread-ii/minimize_malware_spread_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem928
diff --git a/problems/minimize-malware-spread-ii/minimize_malware_spread_ii_test.go b/problems/minimize-malware-spread-ii/minimize_malware_spread_ii_test.go
deleted file mode 100644
index 46b69ff9b..000000000
--- a/problems/minimize-malware-spread-ii/minimize_malware_spread_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem928
diff --git a/problems/minimize-malware-spread/README.md b/problems/minimize-malware-spread/README.md
deleted file mode 100644
index 0adf6f7bc..000000000
--- a/problems/minimize-malware-spread/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../3sum-with-multiplicity "3Sum With Multiplicity")
-　　　　　　　　　　　　　　　　
-[Next >](../long-pressed-name "Long Pressed Name")
-
-## [924. Minimize Malware Spread (Hard)](https://leetcode.com/problems/minimize-malware-spread "尽量减少恶意软件的传播")
-
-<p>You are given a network of <code>n</code> nodes represented as an <code>n x n</code> adjacency matrix <code>graph</code>, where the <code>i<sup>th</sup></code> node is directly connected to the <code>j<sup>th</sup></code> node if <code>graph[i][j] == 1</code>.</p>
-
-<p>Some nodes <code>initial</code> are initially infected by malware. Whenever two nodes are directly connected, and at least one of those two nodes is infected by malware, both nodes will be infected by malware. This spread of malware will continue until no more nodes can be infected in this manner.</p>
-
-<p>Suppose <code>M(initial)</code> is the final number of nodes infected with malware in the entire network after the spread of malware stops. We will remove <strong>exactly one node</strong> from <code>initial</code>.</p>
-
-<p>Return the node that, if removed, would minimize <code>M(initial)</code>. If multiple nodes could be removed to minimize <code>M(initial)</code>, return such a node with <strong>the smallest index</strong>.</p>
-
-<p>Note that if a node was removed from the <code>initial</code> list of infected nodes, it might still be infected later due to the malware spread.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> graph = [[1,1,0],[1,1,0],[0,0,1]], initial = [0,1]
-<strong>Output:</strong> 0
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> graph = [[1,0,0],[0,1,0],[0,0,1]], initial = [0,2]
-<strong>Output:</strong> 0
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> graph = [[1,1,1],[1,1,1],[1,1,1]], initial = [1,2]
-<strong>Output:</strong> 1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == graph.length</code></li>
-	<li><code>n == graph[i].length</code></li>
-	<li><code>2 &lt;= n &lt;= 300</code></li>
-	<li><code>graph[i][j]</code> is <code>0</code> or <code>1</code>.</li>
-	<li><code>graph[i][j] == graph[j][i]</code></li>
-	<li><code>graph[i][i] == 1</code></li>
-	<li><code>1 &lt;= initial.length &lt;= n</code></li>
-	<li><code>0 &lt;= initial[i] &lt;= n - 1</code></li>
-	<li>All the integers in <code>initial</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/minimize-malware-spread/minimize_malware_spread.go b/problems/minimize-malware-spread/minimize_malware_spread.go
deleted file mode 100644
index 01b02a043..000000000
--- a/problems/minimize-malware-spread/minimize_malware_spread.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem924
diff --git a/problems/minimize-malware-spread/minimize_malware_spread_test.go b/problems/minimize-malware-spread/minimize_malware_spread_test.go
deleted file mode 100644
index 01b02a043..000000000
--- a/problems/minimize-malware-spread/minimize_malware_spread_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem924
diff --git a/problems/minimize-max-distance-to-gas-station/README.md b/problems/minimize-max-distance-to-gas-station/README.md
deleted file mode 100644
index 61cb492c8..000000000
--- a/problems/minimize-max-distance-to-gas-station/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sliding-puzzle "Sliding Puzzle")
-　　　　　　　　　　　　　　　　
-[Next >](../global-and-local-inversions "Global and Local Inversions")
-
-## [774. Minimize Max Distance to Gas Station (Hard)](https://leetcode.com/problems/minimize-max-distance-to-gas-station "最小化去加油站的最大距离")
-
-<p>On a horizontal number line, we have gas stations at positions <code>stations[0], stations[1], ..., stations[N-1]</code>, where <code>N = stations.length</code>.</p>
-
-<p>Now, we add <code>K</code> more gas stations so that <strong>D</strong>, the maximum distance between adjacent gas stations, is minimized.</p>
-
-<p>Return the smallest possible value of <strong>D</strong>.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> stations = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], K = 9
-<strong>Output:</strong> 0.500000
-</pre>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>stations.length</code> will be an integer in range <code>[10, 2000]</code>.</li>
-	<li><code>stations[i]</code> will be an integer in range <code>[0, 10^8]</code>.</li>
-	<li><code>K</code> will be an integer in range <code>[1, 10^6]</code>.</li>
-	<li>Answers within <code>10^-6</code> of the true value will be accepted as correct.</li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Koko Eating Bananas](../koko-eating-bananas) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a binary search.  We'll binary search the monotone function "possible(D) = can we use K or less gas stations to ensure each adjacent distance between gas stations is at most D?"
-</details>
diff --git a/problems/minimize-max-distance-to-gas-station/minimize_max_distance_to_gas_station.go b/problems/minimize-max-distance-to-gas-station/minimize_max_distance_to_gas_station.go
deleted file mode 100644
index 65de0eca7..000000000
--- a/problems/minimize-max-distance-to-gas-station/minimize_max_distance_to_gas_station.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem774
diff --git a/problems/minimize-max-distance-to-gas-station/minimize_max_distance_to_gas_station_test.go b/problems/minimize-max-distance-to-gas-station/minimize_max_distance_to_gas_station_test.go
deleted file mode 100644
index 65de0eca7..000000000
--- a/problems/minimize-max-distance-to-gas-station/minimize_max_distance_to_gas_station_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem774
diff --git a/problems/minimize-maximum-pair-sum-in-array/README.md b/problems/minimize-maximum-pair-sum-in-array/README.md
deleted file mode 100644
index dc7eeaccd..000000000
--- a/problems/minimize-maximum-pair-sum-in-array/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../substrings-of-size-three-with-distinct-characters "Substrings of Size Three with Distinct Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../get-biggest-three-rhombus-sums-in-a-grid "Get Biggest Three Rhombus Sums in a Grid")
-
-## [1877. Minimize Maximum Pair Sum in Array (Medium)](https://leetcode.com/problems/minimize-maximum-pair-sum-in-array "数组中最大数对和的最小值")
-
-<p>The <strong>pair sum</strong> of a pair <code>(a,b)</code> is equal to <code>a + b</code>. The <strong>maximum pair sum</strong> is the largest <strong>pair sum</strong> in a list of pairs.</p>
-
-<ul>
-	<li>For example, if we have pairs <code>(1,5)</code>, <code>(2,3)</code>, and <code>(4,4)</code>, the <strong>maximum pair sum</strong> would be <code>max(1+5, 2+3, 4+4) = max(6, 5, 8) = 8</code>.</li>
-</ul>
-
-<p>Given an array <code>nums</code> of <strong>even</strong> length <code>n</code>, pair up the elements of <code>nums</code> into <code>n / 2</code> pairs such that:</p>
-
-<ul>
-	<li>Each element of <code>nums</code> is in <strong>exactly one</strong> pair, and</li>
-	<li>The <strong>maximum pair sum </strong>is <strong>minimized</strong>.</li>
-</ul>
-
-<p>Return <em>the minimized <strong>maximum pair sum</strong> after optimally pairing up the elements</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,5,2,3]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The elements can be paired up into pairs (3,3) and (5,2).
-The maximum pair sum is max(3+3, 5+2) = max(6, 7) = 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,5,4,2,4,6]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> The elements can be paired up into pairs (3,5), (4,4), and (6,2).
-The maximum pair sum is max(3+5, 4+4, 6+2) = max(8, 8, 8) = 8.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>n</code> is <strong>even</strong>.</li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Would sorting help find the optimal order?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Given a specific element, how would you minimize its specific pairwise sum?
-</details>
diff --git a/problems/minimize-product-sum-of-two-arrays/README.md b/problems/minimize-product-sum-of-two-arrays/README.md
deleted file mode 100644
index deb391bad..000000000
--- a/problems/minimize-product-sum-of-two-arrays/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../calculate-special-bonus "Calculate Special Bonus")
-　　　　　　　　　　　　　　　　
-[Next >](../group-employees-of-the-same-salary "Group Employees of the Same Salary")
-
-## [1874. Minimize Product Sum of Two Arrays (Medium)](https://leetcode.com/problems/minimize-product-sum-of-two-arrays "两个数组的最小乘积和")
-
-
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is there a particular way we should order the arrays such that the product sum is minimized?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Would you want to multiply two numbers that are closer to one another or further?
-</details>
diff --git a/problems/minimize-rounding-error-to-meet-target/README.md b/problems/minimize-rounding-error-to-meet-target/README.md
deleted file mode 100644
index 6dfbedfbc..000000000
--- a/problems/minimize-rounding-error-to-meet-target/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../campus-bikes "Campus Bikes")
-　　　　　　　　　　　　　　　　
-[Next >](../all-paths-from-source-lead-to-destination "All Paths from Source Lead to Destination")
-
-## [1058. Minimize Rounding Error to Meet Target (Medium)](https://leetcode.com/problems/minimize-rounding-error-to-meet-target "最小化舍入误差以满足目标")
-
-<p>Given an array of prices <code>[p<sub>1</sub>,p<sub>2</sub>...,p<sub>n</sub>]</code> and a <code>target</code>, round each price <code>p<sub>i</sub></code> to <code>Round<sub>i</sub>(p<sub>i</sub>)</code> so that the rounded array <code>[Round<sub>1</sub>(p<sub>1</sub>),Round<sub>2</sub>(p<sub>2</sub>)...,Round<sub>n</sub>(p<sub>n</sub>)]</code> sums to the given <code>target</code>. Each operation <code>Round<sub>i</sub>(p<sub>i</sub>)</code> could be either <code>Floor(p<sub>i</sub>)</code> or <code>Ceil(p<sub>i</sub>)</code>.</p>
-
-<p>Return the string <code>&quot;-1&quot;</code> if the rounded array is impossible to sum to <code>target</code>. Otherwise, return the smallest rounding error, which is defined as &Sigma; |Round<sub>i</sub>(p<sub>i</sub>) - (p<sub>i</sub>)| for <italic>i</italic> from 1 to <italic>n</italic>, as a string with three places after the decimal.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>prices = <span id="example-input-1-1">[&quot;0.700&quot;,&quot;2.800&quot;,&quot;4.900&quot;]</span>, target = <span id="example-input-1-2">8</span>
-<strong>Output: </strong><span id="example-output-1">&quot;1.000&quot;</span>
-<strong>Explanation: </strong>
-Use Floor, Ceil and Ceil operations to get (0.7 - 0) + (3 - 2.8) + (5 - 4.9) = 0.7 + 0.2 + 0.1 = 1.0 .
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>prices = <span id="example-input-2-1">[&quot;1.500&quot;,&quot;2.500&quot;,&quot;3.500&quot;]</span>, target = <span id="example-input-2-2">10</span>
-<strong>Output: </strong><span id="example-output-2">&quot;-1&quot;</span>
-<strong>Explanation: </strong>
-It is impossible to meet the target.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= prices.length &lt;= 500</code>.</li>
-	<li>Each string of prices <code>prices[i]</code> represents a real number which is between 0 and 1000 and has exactly 3 decimal places.</li>
-	<li><code>target</code> is between 0 and 1000000.</li>
-</ol>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If we have integer values in the array then we just need to subtract the target those integer values, so we reduced the problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Similarly if we have non integer values we have two options to put them flor(value) or ceil(value) = floor(value) + 1, so the idea is to just subtract floor(value).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Now the problem is different for each position we can sum just add 0 or 1 in order to sum the target, minimizing the deltas. This can be solved with DP.
-</details>
diff --git a/problems/minimize-the-difference-between-target-and-chosen-elements/README.md b/problems/minimize-the-difference-between-target-and-chosen-elements/README.md
deleted file mode 100644
index 37fe28b71..000000000
--- a/problems/minimize-the-difference-between-target-and-chosen-elements/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-unique-binary-string "Find Unique Binary String")
-　　　　　　　　　　　　　　　　
-[Next >](../find-array-given-subset-sums "Find Array Given Subset Sums")
-
-## [1981. Minimize the Difference Between Target and Chosen Elements (Medium)](https://leetcode.com/problems/minimize-the-difference-between-target-and-chosen-elements "最小化目标值与所选元素的差")
-
-<p>You are given an <code>m x n</code> integer matrix <code>mat</code> and an integer <code>target</code>.</p>
-
-<p>Choose one integer from <strong>each row</strong> in the matrix such that the <strong>absolute difference</strong> between <code>target</code> and the <strong>sum</strong> of the chosen elements is <strong>minimized</strong>.</p>
-
-<p>Return <em>the <strong>minimum absolute difference</strong></em>.</p>
-
-<p>The <strong>absolute difference</strong> between two numbers <code>a</code> and <code>b</code> is the absolute value of <code>a - b</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/03/matrix1.png" style="width: 181px; height: 181px;" />
-<pre>
-<strong>Input:</strong> mat = [[1,2,3],[4,5,6],[7,8,9]], target = 13
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> One possible choice is to:
-- Choose 1 from the first row.
-- Choose 5 from the second row.
-- Choose 7 from the third row.
-The sum of the chosen elements is 13, which equals the target, so the absolute difference is 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/03/matrix1-1.png" style="width: 61px; height: 181px;" />
-<pre>
-<strong>Input:</strong> mat = [[1],[2],[3]], target = 100
-<strong>Output:</strong> 94
-<strong>Explanation:</strong> The best possible choice is to:
-- Choose 1 from the first row.
-- Choose 2 from the second row.
-- Choose 3 from the third row.
-The sum of the chosen elements is 6, and the absolute difference is 94.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/03/matrix1-3.png" style="width: 301px; height: 61px;" />
-<pre>
-<strong>Input:</strong> mat = [[1,2,9,8,7]], target = 6
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The best choice is to choose 7 from the first row.
-The absolute difference is 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 70</code></li>
-	<li><code>1 &lt;= mat[i][j] &lt;= 70</code></li>
-	<li><code>1 &lt;= target &lt;= 800</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The sum of chosen elements will not be too large. Consider using a hash set to record all possible sums while iterating each row.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Instead of keeping track of all possible sums, since in each row, we are adding positive numbers, only keep those that can be a candidate, not exceeding the target by too much.
-</details>
diff --git a/problems/minimized-maximum-of-products-distributed-to-any-store/README.md b/problems/minimized-maximum-of-products-distributed-to-any-store/README.md
deleted file mode 100644
index 3f1dcfa07..000000000
--- a/problems/minimized-maximum-of-products-distributed-to-any-store/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../vowels-of-all-substrings "Vowels of All Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-path-quality-of-a-graph "Maximum Path Quality of a Graph")
-
-## [2064. Minimized Maximum of Products Distributed to Any Store (Medium)](https://leetcode.com/problems/minimized-maximum-of-products-distributed-to-any-store "分配给商店的最多商品的最小值")
-
-<p>You are given an integer <code>n</code> indicating there are <code>n</code> specialty retail stores. There are <code>m</code> product types of varying amounts, which are given as a <strong>0-indexed</strong> integer array <code>quantities</code>, where <code>quantities[i]</code> represents the number of products of the <code>i<sup>th</sup></code> product type.</p>
-
-<p>You need to distribute <strong>all products</strong> to the retail stores following these rules:</p>
-
-<ul>
-	<li>A store can only be given <strong>at most one product type</strong> but can be given <strong>any</strong> amount of it.</li>
-	<li>After distribution, each store will have been given some number of products (possibly <code>0</code>). Let <code>x</code> represent the maximum number of products given to any store. You want <code>x</code> to be as small as possible, i.e., you want to <strong>minimize</strong> the <strong>maximum</strong> number of products that are given to any store.</li>
-</ul>
-
-<p>Return <em>the minimum possible</em> <code>x</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6, quantities = [11,6]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> One optimal way is:
-- The 11 products of type 0 are distributed to the first four stores in these amounts: 2, 3, 3, 3
-- The 6 products of type 1 are distributed to the other two stores in these amounts: 3, 3
-The maximum number of products given to any store is max(2, 3, 3, 3, 3, 3) = 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7, quantities = [15,10,10]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> One optimal way is:
-- The 15 products of type 0 are distributed to the first three stores in these amounts: 5, 5, 5
-- The 10 products of type 1 are distributed to the next two stores in these amounts: 5, 5
-- The 10 products of type 2 are distributed to the last two stores in these amounts: 5, 5
-The maximum number of products given to any store is max(5, 5, 5, 5, 5, 5, 5) = 5.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, quantities = [100000]
-<strong>Output:</strong> 100000
-<strong>Explanation:</strong> The only optimal way is:
-- The 100000 products of type 0 are distributed to the only store.
-The maximum number of products given to any store is max(100000) = 100000.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == quantities.length</code></li>
-	<li><code>1 &lt;= m &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= quantities[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There exists a monotonic nature such that when x is smaller than some number, there will be no way to distribute, and when x is not smaller than that number, there will always be a way to distribute.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you are given a number k, where the number of products given to any store does not exceed k, could you determine if all products can be distributed?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Implement a function canDistribute(k), which returns true if you can distribute all products such that any store will not be given more than k products, and returns false if you cannot. Use this function to binary search for the smallest possible k.
-</details>
diff --git a/problems/minimum-absolute-difference-in-bst/README.md b/problems/minimum-absolute-difference-in-bst/README.md
deleted file mode 100644
index 65dc1df78..000000000
--- a/problems/minimum-absolute-difference-in-bst/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minesweeper "Minesweeper")
-　　　　　　　　　　　　　　　　
-[Next >](../lonely-pixel-i "Lonely Pixel I")
-
-## [530. Minimum Absolute Difference in BST (Easy)](https://leetcode.com/problems/minimum-absolute-difference-in-bst "二叉搜索树的最小绝对差")
-
-<p>Given the <code>root</code> of a Binary Search Tree (BST), return <em>the minimum absolute difference between the values of any two different nodes in the tree</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/05/bst1.jpg" style="width: 292px; height: 301px;" />
-<pre>
-<strong>Input:</strong> root = [4,2,6,1,3]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/05/bst2.jpg" style="width: 282px; height: 301px;" />
-<pre>
-<strong>Input:</strong> root = [1,0,48,null,null,12,49]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[2, 10<sup>4</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 783: <a href="https://leetcode.com/problems/minimum-distance-between-bst-nodes/" target="_blank">https://leetcode.com/problems/minimum-distance-between-bst-nodes/</a></p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [K-diff Pairs in an Array](../k-diff-pairs-in-an-array) (Medium)
diff --git a/problems/minimum-absolute-difference-in-bst/minimum_absolute_difference_in_bst.go b/problems/minimum-absolute-difference-in-bst/minimum_absolute_difference_in_bst.go
deleted file mode 100644
index b09ff3c37..000000000
--- a/problems/minimum-absolute-difference-in-bst/minimum_absolute_difference_in_bst.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem530
diff --git a/problems/minimum-absolute-difference-in-bst/minimum_absolute_difference_in_bst_test.go b/problems/minimum-absolute-difference-in-bst/minimum_absolute_difference_in_bst_test.go
deleted file mode 100644
index b09ff3c37..000000000
--- a/problems/minimum-absolute-difference-in-bst/minimum_absolute_difference_in_bst_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem530
diff --git a/problems/minimum-absolute-difference-queries/README.md b/problems/minimum-absolute-difference-queries/README.md
deleted file mode 100644
index a87e08fff..000000000
--- a/problems/minimum-absolute-difference-queries/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-sub-islands "Count Sub Islands")
-　　　　　　　　　　　　　　　　
-[Next >](../count-salary-categories "Count Salary Categories")
-
-## [1906. Minimum Absolute Difference Queries (Medium)](https://leetcode.com/problems/minimum-absolute-difference-queries "查询差绝对值的最小值")
-
-<p>The <strong>minimum absolute difference</strong> of an array <code>a</code> is defined as the <strong>minimum value</strong> of <code>|a[i] - a[j]|</code>, where <code>0 &lt;= i &lt; j &lt; a.length</code> and <code>a[i] != a[j]</code>. If all elements of <code>a</code> are the <strong>same</strong>, the minimum absolute difference is <code>-1</code>.</p>
-
-<ul>
-	<li>For example, the minimum absolute difference of the array <code>[5,<u>2</u>,<u>3</u>,7,2]</code> is <code>|2 - 3| = 1</code>. Note that it is not <code>0</code> because <code>a[i]</code> and <code>a[j]</code> must be different.</li>
-</ul>
-
-<p>You are given an integer array <code>nums</code> and the array <code>queries</code> where <code>queries[i] = [l<sub>i</sub>, r<sub>i</sub>]</code>. For each query <code>i</code>, compute the <strong>minimum absolute difference</strong> of the <strong>subarray</strong> <code>nums[l<sub>i</sub>...r<sub>i</sub>]</code> containing the elements of <code>nums</code> between the <strong>0-based</strong> indices <code>l<sub>i</sub></code> and <code>r<sub>i</sub></code> (<strong>inclusive</strong>).</p>
-
-<p>Return <em>an <strong>array</strong> </em><code>ans</code> <em>where</em> <code>ans[i]</code> <em>is the answer to the</em> <code>i<sup>th</sup></code> <em>query</em>.</p>
-
-<p>A <strong>subarray</strong> is a contiguous sequence of elements in an array.</p>
-
-<p>The value of <code>|x|</code> is defined as:</p>
-
-<ul>
-	<li><code>x</code> if <code>x &gt;= 0</code>.</li>
-	<li><code>-x</code> if <code>x &lt; 0</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,4,8], queries = [[0,1],[1,2],[2,3],[0,3]]
-<strong>Output:</strong> [2,1,4,1]
-<strong>Explanation:</strong> The queries are processed as follows:
-- queries[0] = [0,1]: The subarray is [<u>1</u>,<u>3</u>] and the minimum absolute difference is |1-3| = 2.
-- queries[1] = [1,2]: The subarray is [<u>3</u>,<u>4</u>] and the minimum absolute difference is |3-4| = 1.
-- queries[2] = [2,3]: The subarray is [<u>4</u>,<u>8</u>] and the minimum absolute difference is |4-8| = 4.
-- queries[3] = [0,3]: The subarray is [1,<u>3</u>,<u>4</u>,8] and the minimum absolute difference is |3-4| = 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,5,2,2,7,10], queries = [[2,3],[0,2],[0,5],[3,5]]
-<strong>Output:</strong> [-1,1,1,3]
-<strong>Explanation: </strong>The queries are processed as follows:
-- queries[0] = [2,3]: The subarray is [2,2] and the minimum absolute difference is -1 because all the
-  elements are the same.
-- queries[1] = [0,2]: The subarray is [<u>4</u>,<u>5</u>,2] and the minimum absolute difference is |4-5| = 1.
-- queries[2] = [0,5]: The subarray is [<u>4</u>,<u>5</u>,2,2,7,10] and the minimum absolute difference is |4-5| = 1.
-- queries[3] = [3,5]: The subarray is [2,<u>7</u>,<u>10</u>] and the minimum absolute difference is |7-10| = 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-	<li><code>1 &lt;= queries.length &lt;= 2&nbsp;* 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= l<sub>i</sub> &lt; r<sub>i</sub> &lt; nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How does the maximum value being 100 help us?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we tell if a number exists in a given range?
-</details>
diff --git a/problems/minimum-absolute-difference/README.md b/problems/minimum-absolute-difference/README.md
deleted file mode 100644
index a2d9fe276..000000000
--- a/problems/minimum-absolute-difference/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-time-to-build-blocks "Minimum Time to Build Blocks")
-　　　　　　　　　　　　　　　　
-[Next >](../ugly-number-iii "Ugly Number III")
-
-## [1200. Minimum Absolute Difference (Easy)](https://leetcode.com/problems/minimum-absolute-difference "最小绝对差")
-
-<p>Given an array of <strong>distinct</strong> integers <code>arr</code>, find all pairs of elements with the minimum absolute difference of any two elements.</p>
-
-<p>Return a list of pairs in ascending order(with respect to pairs), each pair <code>[a, b]</code> follows</p>
-
-<ul>
-	<li><code>a, b</code> are from <code>arr</code></li>
-	<li><code>a &lt; b</code></li>
-	<li><code>b - a</code> equals to the minimum absolute difference of any two elements in <code>arr</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,2,1,3]
-<strong>Output:</strong> [[1,2],[2,3],[3,4]]
-<strong>Explanation: </strong>The minimum absolute difference is 1. List all pairs with difference equal to 1 in ascending order.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,3,6,10,15]
-<strong>Output:</strong> [[1,3]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,8,-10,23,19,-4,-14,27]
-<strong>Output:</strong> [[-14,-10],[19,23],[23,27]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>6</sup> &lt;= arr[i] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Minimum Cost of Buying Candies With Discount](../minimum-cost-of-buying-candies-with-discount) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the minimum absolute difference between two elements in the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The minimum absolute difference must be a difference between two consecutive elements in the sorted array.
-</details>
diff --git a/problems/minimum-absolute-sum-difference/README.md b/problems/minimum-absolute-sum-difference/README.md
deleted file mode 100644
index 9fc9ca593..000000000
--- a/problems/minimum-absolute-sum-difference/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../finding-the-users-active-minutes "Finding the Users Active Minutes")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-different-subsequences-gcds "Number of Different Subsequences GCDs")
-
-## [1818. Minimum Absolute Sum Difference (Medium)](https://leetcode.com/problems/minimum-absolute-sum-difference "绝对差值和")
-
-<p>You are given two positive integer arrays <code>nums1</code> and <code>nums2</code>, both of length <code>n</code>.</p>
-
-<p>The <strong>absolute sum difference</strong> of arrays <code>nums1</code> and <code>nums2</code> is defined as the <strong>sum</strong> of <code>|nums1[i] - nums2[i]|</code> for each <code>0 &lt;= i &lt; n</code> (<strong>0-indexed</strong>).</p>
-
-<p>You can replace <strong>at most one</strong> element of <code>nums1</code> with <strong>any</strong> other element in <code>nums1</code> to <strong>minimize</strong> the absolute sum difference.</p>
-
-<p>Return the <em>minimum absolute sum difference <strong>after</strong> replacing at most one<strong> </strong>element in the array <code>nums1</code>.</em> Since the answer may be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p><code>|x|</code> is defined as:</p>
-
-<ul>
-	<li><code>x</code> if <code>x &gt;= 0</code>, or</li>
-	<li><code>-x</code> if <code>x &lt; 0</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,7,5], nums2 = [2,3,5]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>There are two possible optimal solutions:
-- Replace the second element with the first: [1,<u><strong>7</strong></u>,5] =&gt; [1,<u><strong>1</strong></u>,5], or
-- Replace the second element with the third: [1,<u><strong>7</strong></u>,5] =&gt; [1,<u><strong>5</strong></u>,5].
-Both will yield an absolute sum difference of <code>|1-2| + (|1-3| or |5-3|) + |5-5| = </code>3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [2,4,6,8,10], nums2 = [2,4,6,8,10]
-<strong>Output:</strong> 0
-<strong>Explanation: </strong>nums1 is equal to nums2 so no replacement is needed. This will result in an 
-absolute sum difference of 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,10,4,4,2,7], nums2 = [9,3,5,1,7,4]
-<strong>Output:</strong> 20
-<strong>Explanation: </strong>Replace the first element with the second: [<u><strong>1</strong></u>,10,4,4,2,7] =&gt; [<u><strong>10</strong></u>,10,4,4,2,7].
-This yields an absolute sum difference of <code>|10-9| + |10-3| + |4-5| + |4-1| + |2-7| + |7-4| = 20</code>
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums1.length</code></li>
-	<li><code>n == nums2.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums1[i], nums2[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Go through each element and test the optimal replacements.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-There are only 2 possible replacements for each element (higher and lower) that are optimal.
-</details>
diff --git a/problems/minimum-add-to-make-parentheses-valid/README.md b/problems/minimum-add-to-make-parentheses-valid/README.md
deleted file mode 100644
index f22abd1a7..000000000
--- a/problems/minimum-add-to-make-parentheses-valid/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-music-playlists "Number of Music Playlists")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-array-by-parity-ii "Sort Array By Parity II")
-
-## [921. Minimum Add to Make Parentheses Valid (Medium)](https://leetcode.com/problems/minimum-add-to-make-parentheses-valid "使括号有效的最少添加")
-
-<p>A parentheses string is valid if and only if:</p>
-
-<ul>
-	<li>It is the empty string,</li>
-	<li>It can be written as <code>AB</code> (<code>A</code> concatenated with <code>B</code>), where <code>A</code> and <code>B</code> are valid strings, or</li>
-	<li>It can be written as <code>(A)</code>, where <code>A</code> is a valid string.</li>
-</ul>
-
-<p>You are given a parentheses string <code>s</code>. In one move, you can insert a parenthesis at any position of the string.</p>
-
-<ul>
-	<li>For example, if <code>s = &quot;()))&quot;</code>, you can insert an opening parenthesis to be <code>&quot;(<strong>(</strong>)))&quot;</code> or a closing parenthesis to be <code>&quot;())<strong>)</strong>)&quot;</code>.</li>
-</ul>
-
-<p>Return <em>the minimum number of moves required to make </em><code>s</code><em> valid</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;())&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(((&quot;
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s[i]</code> is either <code>&#39;(&#39;</code> or <code>&#39;)&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Minimum Number of Swaps to Make the String Balanced](../minimum-number-of-swaps-to-make-the-string-balanced) (Medium)
diff --git a/problems/minimum-add-to-make-parentheses-valid/minimum_add_to_make_parentheses_valid.go b/problems/minimum-add-to-make-parentheses-valid/minimum_add_to_make_parentheses_valid.go
deleted file mode 100644
index a03a3f50a..000000000
--- a/problems/minimum-add-to-make-parentheses-valid/minimum_add_to_make_parentheses_valid.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem921
diff --git a/problems/minimum-add-to-make-parentheses-valid/minimum_add_to_make_parentheses_valid_test.go b/problems/minimum-add-to-make-parentheses-valid/minimum_add_to_make_parentheses_valid_test.go
deleted file mode 100644
index a03a3f50a..000000000
--- a/problems/minimum-add-to-make-parentheses-valid/minimum_add_to_make_parentheses_valid_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem921
diff --git a/problems/minimum-adjacent-swaps-for-k-consecutive-ones/README.md b/problems/minimum-adjacent-swaps-for-k-consecutive-ones/README.md
deleted file mode 100644
index 2f7a8dce0..000000000
--- a/problems/minimum-adjacent-swaps-for-k-consecutive-ones/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-binary-string-after-change "Maximum Binary String After Change")
-　　　　　　　　　　　　　　　　
-[Next >](../determine-if-string-halves-are-alike "Determine if String Halves Are Alike")
-
-## [1703. Minimum Adjacent Swaps for K Consecutive Ones (Hard)](https://leetcode.com/problems/minimum-adjacent-swaps-for-k-consecutive-ones "得到连续 K 个 1 的最少相邻交换次数")
-
-<p>You are given an integer array, <code>nums</code>, and an integer <code>k</code>. <code>nums</code> comprises of only <code>0</code>&#39;s and <code>1</code>&#39;s. In one move, you can choose two <strong>adjacent</strong> indices and swap their values.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of moves required so that </em><code>nums</code><em> has </em><code>k</code><em> <strong>consecutive</strong> </em><code>1</code><em>&#39;s</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,0,0,1,0,1], k = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> In 1 move, nums could be [1,0,0,0,<u>1</u>,<u>1</u>] and have 2 consecutive 1&#39;s.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,0,0,0,0,0,1,1], k = 3
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> In 5 moves, the leftmost 1 can be shifted right until nums = [0,0,0,0,0,<u>1</u>,<u>1</u>,<u>1</u>].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,0,1], k = 2
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> nums already has 2 consecutive 1&#39;s.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums[i]</code> is <code>0</code> or <code>1</code>.</li>
-	<li><code>1 &lt;= k &lt;= sum(nums)</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Minimum Swaps to Group All 1's Together](../minimum-swaps-to-group-all-1s-together) (Medium)
-  1. [Minimum Number of Operations to Make Array Continuous](../minimum-number-of-operations-to-make-array-continuous) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Choose k 1s and determine how many steps are required to move them into 1 group.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Maintain a sliding window of k 1s, and maintain the steps required to group them.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-When you slide the window across, should you move the group to the right? Once you move the group to the right, it will never need to slide to the left again.
-</details>
diff --git a/problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number/README.md b/problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number/README.md
deleted file mode 100644
index 59c7fc47c..000000000
--- a/problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../splitting-a-string-into-descending-consecutive-values "Splitting a String Into Descending Consecutive Values")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-interval-to-include-each-query "Minimum Interval to Include Each Query")
-
-## [1850. Minimum Adjacent Swaps to Reach the Kth Smallest Number (Medium)](https://leetcode.com/problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number "邻位交换的最小次数")
-
-<p>You are given a string <code>num</code>, representing a large integer, and an integer <code>k</code>.</p>
-
-<p>We call some integer <strong>wonderful</strong> if it is a <strong>permutation</strong> of the digits in <code>num</code> and is <strong>greater in value</strong> than <code>num</code>. There can be many wonderful integers. However, we only care about the <strong>smallest-valued</strong> ones.</p>
-
-<ul>
-	<li>For example, when <code>num = &quot;5489355142&quot;</code>:
-	<ul>
-		<li>The 1<sup>st</sup> smallest wonderful integer is <code>&quot;5489355214&quot;</code>.</li>
-		<li>The 2<sup>nd</sup> smallest wonderful integer is <code>&quot;5489355241&quot;</code>.</li>
-		<li>The 3<sup>rd</sup> smallest wonderful integer is <code>&quot;5489355412&quot;</code>.</li>
-		<li>The 4<sup>th</sup> smallest wonderful integer is <code>&quot;5489355421&quot;</code>.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <em>the <strong>minimum number of adjacent digit swaps</strong> that needs to be applied to </em><code>num</code><em> to reach the </em><code>k<sup>th</sup></code><em><strong> smallest wonderful</strong> integer</em>.</p>
-
-<p>The tests are generated in such a way that <code>k<sup>th</sup></code>&nbsp;smallest wonderful integer exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;5489355142&quot;, k = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The 4<sup>th</sup> smallest wonderful number is &quot;5489355421&quot;. To get this number:
-- Swap index 7 with index 8: &quot;5489355<u>14</u>2&quot; -&gt; &quot;5489355<u>41</u>2&quot;
-- Swap index 8 with index 9: &quot;54893554<u>12</u>&quot; -&gt; &quot;54893554<u>21</u>&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;11112&quot;, k = 4
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The 4<sup>th</sup> smallest wonderful number is &quot;21111&quot;. To get this number:
-- Swap index 3 with index 4: &quot;111<u>12</u>&quot; -&gt; &quot;111<u>21</u>&quot;
-- Swap index 2 with index 3: &quot;11<u>12</u>1&quot; -&gt; &quot;11<u>21</u>1&quot;
-- Swap index 1 with index 2: &quot;1<u>12</u>11&quot; -&gt; &quot;1<u>21</u>11&quot;
-- Swap index 0 with index 1: &quot;<u>12</u>111&quot; -&gt; &quot;<u>21</u>111&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;00123&quot;, k = 1
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The 1<sup>st</sup> smallest wonderful number is &quot;00132&quot;. To get this number:
-- Swap index 3 with index 4: &quot;001<u>23</u>&quot; -&gt; &quot;001<u>32</u>&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= num.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= k &lt;= 1000</code></li>
-	<li><code>num</code> only consists of digits.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the next permutation of the given string k times.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to move each element to its correct position and calculate the number of steps.
-</details>
diff --git a/problems/minimum-area-rectangle-ii/README.md b/problems/minimum-area-rectangle-ii/README.md
deleted file mode 100644
index c413480e8..000000000
--- a/problems/minimum-area-rectangle-ii/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-width-ramp "Maximum Width Ramp")
-　　　　　　　　　　　　　　　　
-[Next >](../least-operators-to-express-number "Least Operators to Express Number")
-
-## [963. Minimum Area Rectangle II (Medium)](https://leetcode.com/problems/minimum-area-rectangle-ii "最小面积矩形 II")
-
-<p>You are given an array of points in the <strong>X-Y</strong> plane <code>points</code> where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>.</p>
-
-<p>Return <em>the minimum area of any rectangle formed from these points, with sides <strong>not necessarily parallel</strong> to the X and Y axes</em>. If there is not any such rectangle, return <code>0</code>.</p>
-
-<p>Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/21/1a.png" style="width: 398px; height: 400px;" />
-<pre>
-<strong>Input:</strong> points = [[1,2],[2,1],[1,0],[0,1]]
-<strong>Output:</strong> 2.00000
-<strong>Explanation:</strong> The minimum area rectangle occurs at [1,2],[2,1],[1,0],[0,1], with an area of 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/22/2.png" style="width: 400px; height: 251px;" />
-<pre>
-<strong>Input:</strong> points = [[0,1],[2,1],[1,1],[1,0],[2,0]]
-<strong>Output:</strong> 1.00000
-<strong>Explanation:</strong> The minimum area rectangle occurs at [1,0],[1,1],[2,1],[2,0], with an area of 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/22/3.png" style="width: 383px; height: 400px;" />
-<pre>
-<strong>Input:</strong> points = [[0,3],[1,2],[3,1],[1,3],[2,1]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no possible rectangle to form from these points.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= points.length &lt;= 50</code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 4 * 10<sup>4</sup></code></li>
-	<li>All the given points are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
diff --git a/problems/minimum-area-rectangle-ii/minimum_area_rectangle_ii.go b/problems/minimum-area-rectangle-ii/minimum_area_rectangle_ii.go
deleted file mode 100644
index 3c95cd7d6..000000000
--- a/problems/minimum-area-rectangle-ii/minimum_area_rectangle_ii.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem963
-
-func minAreaFreeRect(points [][]int) float64 {
-	return 0
-}
diff --git a/problems/minimum-area-rectangle/README.md b/problems/minimum-area-rectangle/README.md
deleted file mode 100644
index 45969bc7e..000000000
--- a/problems/minimum-area-rectangle/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-sum-of-bst "Range Sum of BST")
-　　　　　　　　　　　　　　　　
-[Next >](../distinct-subsequences-ii "Distinct Subsequences II")
-
-## [939. Minimum Area Rectangle (Medium)](https://leetcode.com/problems/minimum-area-rectangle "最小面积矩形")
-
-<p>You are given an array of points in the <strong>X-Y</strong> plane <code>points</code> where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>.</p>
-
-<p>Return <em>the minimum area of a rectangle formed from these points, with sides parallel to the X and Y axes</em>. If there is not any such rectangle, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/03/rec1.JPG" style="width: 500px; height: 447px;" />
-<pre>
-<strong>Input:</strong> points = [[1,1],[1,3],[3,1],[3,3],[2,2]]
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/03/rec2.JPG" style="width: 500px; height: 477px;" />
-<pre>
-<strong>Input:</strong> points = [[1,1],[1,3],[3,1],[3,3],[4,1],[4,3]]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= points.length &lt;= 500</code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 4 * 10<sup>4</sup></code></li>
-	<li>All the given points are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/minimum-area-rectangle/minimum_area_rectangle.go b/problems/minimum-area-rectangle/minimum_area_rectangle.go
deleted file mode 100644
index d7e1424fe..000000000
--- a/problems/minimum-area-rectangle/minimum_area_rectangle.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem939
diff --git a/problems/minimum-area-rectangle/minimum_area_rectangle_test.go b/problems/minimum-area-rectangle/minimum_area_rectangle_test.go
deleted file mode 100644
index d7e1424fe..000000000
--- a/problems/minimum-area-rectangle/minimum_area_rectangle_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem939
diff --git a/problems/minimum-ascii-delete-sum-for-two-strings/README.md b/problems/minimum-ascii-delete-sum-for-two-strings/README.md
deleted file mode 100644
index 715c4728e..000000000
--- a/problems/minimum-ascii-delete-sum-for-two-strings/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-distinct-islands-ii "Number of Distinct Islands II")
-　　　　　　　　　　　　　　　　
-[Next >](../subarray-product-less-than-k "Subarray Product Less Than K")
-
-## [712. Minimum ASCII Delete Sum for Two Strings (Medium)](https://leetcode.com/problems/minimum-ascii-delete-sum-for-two-strings "两个字符串的最小ASCII删除和")
-
-<p>Given two strings <code>s1</code> and&nbsp;<code>s2</code>, return <em>the lowest <strong>ASCII</strong> sum of deleted characters to make two strings equal</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;sea&quot;, s2 = &quot;eat&quot;
-<strong>Output:</strong> 231
-<strong>Explanation:</strong> Deleting &quot;s&quot; from &quot;sea&quot; adds the ASCII value of &quot;s&quot; (115) to the sum.
-Deleting &quot;t&quot; from &quot;eat&quot; adds 116 to the sum.
-At the end, both strings are equal, and 115 + 116 = 231 is the minimum sum possible to achieve this.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;delete&quot;, s2 = &quot;leet&quot;
-<strong>Output:</strong> 403
-<strong>Explanation:</strong> Deleting &quot;dee&quot; from &quot;delete&quot; to turn the string into &quot;let&quot;,
-adds 100[d] + 101[e] + 101[e] to the sum.
-Deleting &quot;e&quot; from &quot;leet&quot; adds 101[e] to the sum.
-At the end, both strings are equal to &quot;let&quot;, and the answer is 100+101+101+101 = 403.
-If instead we turned both strings into &quot;lee&quot; or &quot;eet&quot;, we would get answers of 433 or 417, which are higher.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s1.length, s2.length &lt;= 1000</code></li>
-	<li><code>s1</code> and <code>s2</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Edit Distance](../edit-distance) (Hard)
-  1. [Longest Increasing Subsequence](../longest-increasing-subsequence) (Medium)
-  1. [Delete Operation for Two Strings](../delete-operation-for-two-strings) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let dp(i, j) be the answer for inputs s1[i:] and s2[j:].
-</details>
diff --git a/problems/minimum-ascii-delete-sum-for-two-strings/minimum_ascii_delete_sum_for_two_strings.go b/problems/minimum-ascii-delete-sum-for-two-strings/minimum_ascii_delete_sum_for_two_strings.go
deleted file mode 100644
index d32b0b4b0..000000000
--- a/problems/minimum-ascii-delete-sum-for-two-strings/minimum_ascii_delete_sum_for_two_strings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem712
diff --git a/problems/minimum-ascii-delete-sum-for-two-strings/minimum_ascii_delete_sum_for_two_strings_test.go b/problems/minimum-ascii-delete-sum-for-two-strings/minimum_ascii_delete_sum_for_two_strings_test.go
deleted file mode 100644
index d32b0b4b0..000000000
--- a/problems/minimum-ascii-delete-sum-for-two-strings/minimum_ascii_delete_sum_for_two_strings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem712
diff --git a/problems/minimum-changes-to-make-alternating-binary-string/README.md b/problems/minimum-changes-to-make-alternating-binary-string/README.md
deleted file mode 100644
index 88450664e..000000000
--- a/problems/minimum-changes-to-make-alternating-binary-string/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../recyclable-and-low-fat-products "Recyclable and Low Fat Products")
-　　　　　　　　　　　　　　　　
-[Next >](../count-number-of-homogenous-substrings "Count Number of Homogenous Substrings")
-
-## [1758. Minimum Changes To Make Alternating Binary String (Easy)](https://leetcode.com/problems/minimum-changes-to-make-alternating-binary-string "生成交替二进制字符串的最少操作数")
-
-<p>You are given a string <code>s</code> consisting only of the characters <code>&#39;0&#39;</code> and <code>&#39;1&#39;</code>. In one operation, you can change any <code>&#39;0&#39;</code> to <code>&#39;1&#39;</code> or vice versa.</p>
-
-<p>The string is called alternating if no two adjacent characters are equal. For example, the string <code>&quot;010&quot;</code> is alternating, while the string <code>&quot;0100&quot;</code> is not.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of operations needed to make</em> <code>s</code> <em>alternating</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0100&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> If you change the last character to &#39;1&#39;, s will be &quot;0101&quot;, which is alternating.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;10&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> s is already alternating.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1111&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You need two operations to reach &quot;0101&quot; or &quot;1010&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think about how the final string will look like.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-It will either start with a '0' and be like '010101010..' or with a '1' and be like '10101010..'
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Try both ways, and check for each way, the number of changes needed to reach it from the given string. The answer is the minimum of both ways.
-</details>
diff --git a/problems/minimum-cost-for-tickets/README.md b/problems/minimum-cost-for-tickets/README.md
deleted file mode 100644
index 3cf8ec9f0..000000000
--- a/problems/minimum-cost-for-tickets/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../triples-with-bitwise-and-equal-to-zero "Triples with Bitwise AND Equal To Zero")
-　　　　　　　　　　　　　　　　
-[Next >](../string-without-aaa-or-bbb "String Without AAA or BBB")
-
-## [983. Minimum Cost For Tickets (Medium)](https://leetcode.com/problems/minimum-cost-for-tickets "最低票价")
-
-<p>You have planned some train traveling one year in advance. The days of the year in which you will travel are given as an integer array <code>days</code>. Each day is an integer from <code>1</code> to <code>365</code>.</p>
-
-<p>Train tickets are sold in <strong>three different ways</strong>:</p>
-
-<ul>
-	<li>a <strong>1-day</strong> pass is sold for <code>costs[0]</code> dollars,</li>
-	<li>a <strong>7-day</strong> pass is sold for <code>costs[1]</code> dollars, and</li>
-	<li>a <strong>30-day</strong> pass is sold for <code>costs[2]</code> dollars.</li>
-</ul>
-
-<p>The passes allow that many days of consecutive travel.</p>
-
-<ul>
-	<li>For example, if we get a <strong>7-day</strong> pass on day <code>2</code>, then we can travel for <code>7</code> days: <code>2</code>, <code>3</code>, <code>4</code>, <code>5</code>, <code>6</code>, <code>7</code>, and <code>8</code>.</li>
-</ul>
-
-<p>Return <em>the minimum number of dollars you need to travel every day in the given list of days</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> days = [1,4,6,7,8,20], costs = [2,7,15]
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> For example, here is one way to buy passes that lets you travel your travel plan:
-On day 1, you bought a 1-day pass for costs[0] = $2, which covered day 1.
-On day 3, you bought a 7-day pass for costs[1] = $7, which covered days 3, 4, ..., 9.
-On day 20, you bought a 1-day pass for costs[0] = $2, which covered day 20.
-In total, you spent $11 and covered all the days of your travel.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> days = [1,2,3,4,5,6,7,8,9,10,30,31], costs = [2,7,15]
-<strong>Output:</strong> 17
-<strong>Explanation:</strong> For example, here is one way to buy passes that lets you travel your travel plan:
-On day 1, you bought a 30-day pass for costs[2] = $15 which covered days 1, 2, ..., 30.
-On day 31, you bought a 1-day pass for costs[0] = $2 which covered day 31.
-In total, you spent $17 and covered all the days of your travel.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= days.length &lt;= 365</code></li>
-	<li><code>1 &lt;= days[i] &lt;= 365</code></li>
-	<li><code>days</code> is in strictly increasing order.</li>
-	<li><code>costs.length == 3</code></li>
-	<li><code>1 &lt;= costs[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Coin Change](../coin-change) (Medium)
diff --git a/problems/minimum-cost-for-tickets/minimum_cost_for_tickets.go b/problems/minimum-cost-for-tickets/minimum_cost_for_tickets.go
deleted file mode 100644
index d4918b0f8..000000000
--- a/problems/minimum-cost-for-tickets/minimum_cost_for_tickets.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem983
diff --git a/problems/minimum-cost-homecoming-of-a-robot-in-a-grid/README.md b/problems/minimum-cost-homecoming-of-a-robot-in-a-grid/README.md
deleted file mode 100644
index 49d80e975..000000000
--- a/problems/minimum-cost-homecoming-of-a-robot-in-a-grid/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-buckets-required-to-collect-rainwater-from-houses "Minimum Number of Buckets Required to Collect Rainwater from Houses")
-　　　　　　　　　　　　　　　　
-[Next >](../count-fertile-pyramids-in-a-land "Count Fertile Pyramids in a Land")
-
-## [2087. Minimum Cost Homecoming of a Robot in a Grid (Medium)](https://leetcode.com/problems/minimum-cost-homecoming-of-a-robot-in-a-grid "网格图中机器人回家的最小代价")
-
-<p>There is an <code>m x n</code> grid, where <code>(0, 0)</code> is the top-left cell and <code>(m - 1, n - 1)</code> is the bottom-right cell. You are given an integer array <code>startPos</code> where <code>startPos = [start<sub>row</sub>, start<sub>col</sub>]</code> indicates that <strong>initially</strong>, a <strong>robot</strong> is at the cell <code>(start<sub>row</sub>, start<sub>col</sub>)</code>. You are also given an integer array <code>homePos</code> where <code>homePos = [home<sub>row</sub>, home<sub>col</sub>]</code> indicates that its <strong>home</strong> is at the cell <code>(home<sub>row</sub>, home<sub>col</sub>)</code>.</p>
-
-<p>The robot needs to go to its home. It can move one cell in four directions: <strong>left</strong>, <strong>right</strong>, <strong>up</strong>, or <strong>down</strong>, and it can not move outside the boundary. Every move incurs some cost. You are further given two <strong>0-indexed</strong> integer arrays: <code>rowCosts</code> of length <code>m</code> and <code>colCosts</code> of length <code>n</code>.</p>
-
-<ul>
-	<li>If the robot moves <strong>up</strong> or <strong>down</strong> into a cell whose <strong>row</strong> is <code>r</code>, then this move costs <code>rowCosts[r]</code>.</li>
-	<li>If the robot moves <strong>left</strong> or <strong>right</strong> into a cell whose <strong>column</strong> is <code>c</code>, then this move costs <code>colCosts[c]</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum total cost</strong> for this robot to return home</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/11/eg-1.png" style="width: 282px; height: 217px;" />
-<pre>
-<strong>Input:</strong> startPos = [1, 0], homePos = [2, 3], rowCosts = [5, 4, 3], colCosts = [8, 2, 6, 7]
-<strong>Output:</strong> 18
-<strong>Explanation:</strong> One optimal path is that:
-Starting from (1, 0)
--&gt; It goes down to (<u><strong>2</strong></u>, 0). This move costs rowCosts[2] = 3.
--&gt; It goes right to (2, <u><strong>1</strong></u>). This move costs colCosts[1] = 2.
--&gt; It goes right to (2, <u><strong>2</strong></u>). This move costs colCosts[2] = 6.
--&gt; It goes right to (2, <u><strong>3</strong></u>). This move costs colCosts[3] = 7.
-The total cost is 3 + 2 + 6 + 7 = 18</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> startPos = [0, 0], homePos = [0, 0], rowCosts = [5], colCosts = [26]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The robot is already at its home. Since no moves occur, the total cost is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == rowCosts.length</code></li>
-	<li><code>n == colCosts.length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= rowCosts[r], colCosts[c] &lt;= 10<sup>4</sup></code></li>
-	<li><code>startPos.length == 2</code></li>
-	<li><code>homePos.length == 2</code></li>
-	<li><code>0 &lt;= start<sub>row</sub>, home<sub>row</sub> &lt; m</code></li>
-	<li><code>0 &lt;= start<sub>col</sub>, home<sub>col</sub> &lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Irrespective of what path the robot takes, it will have to traverse all the rows between startRow and homeRow and all the columns between startCol and homeCol.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Hence, making any other move other than traversing the required rows and columns will potentially incur more cost which can be avoided.
-</details>
diff --git a/problems/minimum-cost-of-buying-candies-with-discount/README.md b/problems/minimum-cost-of-buying-candies-with-discount/README.md
deleted file mode 100644
index f1b686fbd..000000000
--- a/problems/minimum-cost-of-buying-candies-with-discount/README.md
+++ /dev/null
@@ -1,100 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../choose-numbers-from-two-arrays-in-range "Choose Numbers From Two Arrays in Range")
-　　　　　　　　　　　　　　　　
-[Next >](../count-the-hidden-sequences "Count the Hidden Sequences")
-
-## [2144. Minimum Cost of Buying Candies With Discount (Easy)](https://leetcode.com/problems/minimum-cost-of-buying-candies-with-discount "打折购买糖果的最小开销")
-
-<p>A shop is selling candies at a discount. For <strong>every two</strong> candies sold, the shop gives a <strong>third</strong> candy for <strong>free</strong>.</p>
-
-<p>The customer can choose <strong>any</strong> candy to take away for free as long as the cost of the chosen candy is less than or equal to the <strong>minimum</strong> cost of the two candies bought.</p>
-
-<ul>
-	<li>For example, if there are <code>4</code> candies with costs <code>1</code>, <code>2</code>, <code>3</code>, and <code>4</code>, and the customer buys candies with costs <code>2</code> and <code>3</code>, they&nbsp;can take the candy with cost <code>1</code> for free, but not the candy with cost <code>4</code>.</li>
-</ul>
-
-<p>Given a <strong>0-indexed</strong> integer array <code>cost</code>, where <code>cost[i]</code> denotes the cost of the <code>i<sup>th</sup></code> candy, return <em>the <strong>minimum cost</strong> of buying <strong>all</strong> the candies</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> cost = [1,2,3]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> We buy the candies with costs 2 and 3, and take the candy with cost 1 for free.
-The total cost of buying all candies is 2 + 3 = 5. This is the <strong>only</strong> way we can buy the candies.
-Note that we cannot buy candies with costs 1 and 3, and then take the candy with cost 2 for free.
-The cost of the free candy has to be less than or equal to the minimum cost of the purchased candies.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> cost = [6,5,7,9,2,2]
-<strong>Output:</strong> 23
-<strong>Explanation:</strong> The way in which we can get the minimum cost is described below:
-- Buy candies with costs 9 and 7
-- Take the candy with cost 6 for free
-- We buy candies with costs 5 and 2
-- Take the last remaining candy with cost 2 for free
-Hence, the minimum cost to buy all candies is 9 + 7 + 5 + 2 = 23.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> cost = [5,5]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> Since there are only 2 candies, we buy both of them. There is not a third candy we can take for free.
-Hence, the minimum cost to buy all candies is 5 + 5 = 10.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= cost.length &lt;= 100</code></li>
-	<li><code>1 &lt;= cost[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If we consider costs from high to low, what is the maximum cost of a single candy that we can get for free?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we generalize this approach to maximize the costs of the candies we get for free?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Can “sorting” the array help us find the minimum cost?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-If we consider costs from high to low, what is the maximum cost of a single candy that we can get for free?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-How can we generalize this approach to maximize the costs of the candies we get for free?
-</details>
-
-<details>
-<summary>Hint 6</summary>
-Can “sorting” the array help us find the minimum cost?
-</details>
diff --git a/problems/minimum-cost-to-change-the-final-value-of-expression/README.md b/problems/minimum-cost-to-change-the-final-value-of-expression/README.md
deleted file mode 100644
index 382e822b6..000000000
--- a/problems/minimum-cost-to-change-the-final-value-of-expression/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-magic-square "Largest Magic Square")
-　　　　　　　　　　　　　　　　
-[Next >](../redistribute-characters-to-make-all-strings-equal "Redistribute Characters to Make All Strings Equal")
-
-## [1896. Minimum Cost to Change the Final Value of Expression (Hard)](https://leetcode.com/problems/minimum-cost-to-change-the-final-value-of-expression "反转表达式值的最少操作次数")
-
-<p>You are given a <strong>valid</strong> boolean expression as a string <code>expression</code> consisting of the characters <code>&#39;1&#39;</code>,<code>&#39;0&#39;</code>,<code>&#39;&amp;&#39;</code> (bitwise <strong>AND</strong> operator),<code>&#39;|&#39;</code> (bitwise <strong>OR</strong> operator),<code>&#39;(&#39;</code>, and <code>&#39;)&#39;</code>.</p>
-
-<ul>
-	<li>For example, <code>&quot;()1|1&quot;</code> and <code>&quot;(1)&amp;()&quot;</code> are <strong>not valid</strong> while <code>&quot;1&quot;</code>, <code>&quot;(((1))|(0))&quot;</code>, and <code>&quot;1|(0&amp;(1))&quot;</code> are <strong>valid</strong> expressions.</li>
-</ul>
-
-<p>Return<em> the <strong>minimum cost</strong> to change the final value of the expression</em>.</p>
-
-<ul>
-	<li>For example, if <code>expression = &quot;1|1|(0&amp;0)&amp;1&quot;</code>, its <strong>value</strong> is <code>1|1|(0&amp;0)&amp;1 = 1|1|0&amp;1 = 1|0&amp;1 = 1&amp;1 = 1</code>. We want to apply operations so that the<strong> new</strong> expression evaluates to <code>0</code>.</li>
-</ul>
-
-<p>The <strong>cost</strong> of changing the final value of an expression is the <strong>number of operations</strong> performed on the expression. The types of <strong>operations</strong> are described as follows:</p>
-
-<ul>
-	<li>Turn a <code>&#39;1&#39;</code> into a <code>&#39;0&#39;</code>.</li>
-	<li>Turn a <code>&#39;0&#39;</code> into a <code>&#39;1&#39;</code>.</li>
-	<li>Turn a <code>&#39;&amp;&#39;</code> into a <code>&#39;|&#39;</code>.</li>
-	<li>Turn a <code>&#39;|&#39;</code> into a <code>&#39;&amp;&#39;</code>.</li>
-</ul>
-
-<p><strong>Note:</strong> <code>&#39;&amp;&#39;</code> does <strong>not</strong> take precedence over <code>&#39;|&#39;</code> in the <strong>order of calculation</strong>. Evaluate parentheses <strong>first</strong>, then in <strong>left-to-right</strong> order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;1&amp;(0|1)&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> We can turn &quot;1&amp;(0<u><strong>|</strong></u>1)&quot; into &quot;1&amp;(0<u><strong>&amp;</strong></u>1)&quot; by changing the &#39;|&#39; to a &#39;&amp;&#39; using 1 operation.
-The new expression evaluates to 0. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;(0&amp;0)&amp;(0&amp;0&amp;0)&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We can turn &quot;(0<u><strong>&amp;0</strong></u>)<strong><u>&amp;</u></strong>(0&amp;0&amp;0)&quot; into &quot;(0<u><strong>|1</strong></u>)<u><strong>|</strong></u>(0&amp;0&amp;0)&quot; using 3 operations.
-The new expression evaluates to 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;(0|(1|0&amp;1))&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> We can turn &quot;(0|(<u><strong>1</strong></u>|0&amp;1))&quot; into &quot;(0|(<u><strong>0</strong></u>|0&amp;1))&quot; using 1 operation.
-The new expression evaluates to 0.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= expression.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>expression</code>&nbsp;only contains&nbsp;<code>&#39;1&#39;</code>,<code>&#39;0&#39;</code>,<code>&#39;&amp;&#39;</code>,<code>&#39;|&#39;</code>,<code>&#39;(&#39;</code>, and&nbsp;<code>&#39;)&#39;</code></li>
-	<li>All parentheses&nbsp;are properly matched.</li>
-	<li>There will be no empty parentheses (i.e:&nbsp;<code>&quot;()&quot;</code>&nbsp;is not a substring of&nbsp;<code>expression</code>).</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many possible states are there for a given expression?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is there a data structure that we can use to solve the problem optimally?
-</details>
diff --git a/problems/minimum-cost-to-connect-sticks/README.md b/problems/minimum-cost-to-connect-sticks/README.md
deleted file mode 100644
index f2782da11..000000000
--- a/problems/minimum-cost-to-connect-sticks/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-file-system "Design File System")
-　　　　　　　　　　　　　　　　
-[Next >](../optimize-water-distribution-in-a-village "Optimize Water Distribution in a Village")
-
-## [1167. Minimum Cost to Connect Sticks (Medium)](https://leetcode.com/problems/minimum-cost-to-connect-sticks "连接棒材的最低费用")
-
-<p>You have some&nbsp;<code>sticks</code>&nbsp;with&nbsp;positive integer lengths.</p>
-
-<p>You can connect any two sticks of lengths <code>X</code> and <code>Y</code> into one stick&nbsp;by paying a cost of <code>X + Y</code>.&nbsp; You perform this action until there is one stick remaining.</p>
-
-<p>Return&nbsp;the minimum cost of connecting all the given <code>sticks</code> into one stick in this way.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> sticks = [2,4,3]
-<strong>Output:</strong> 14
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> sticks = [1,8,3,5]
-<strong>Output:</strong> 30
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code><span>1 &lt;= sticks.length &lt;= 10^4</span></code></li>
-	<li><code><span>1 &lt;= sticks[i] &lt;= 10^4</span></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Minimum Cost to Merge Stones](../minimum-cost-to-merge-stones) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many times does every stick contribute to the answer?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Some of the sticks will be used more than the others. Which sticks should be used the most/least?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The sticks with long lengths cost a lot so we should use these the least.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-What if we keep merging the two shortest sticks?
-</details>
diff --git a/problems/minimum-cost-to-connect-two-groups-of-points/README.md b/problems/minimum-cost-to-connect-two-groups-of-points/README.md
deleted file mode 100644
index 64c0a7e2b..000000000
--- a/problems/minimum-cost-to-connect-two-groups-of-points/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-non-negative-product-in-a-matrix "Maximum Non Negative Product in a Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../the-most-frequently-ordered-products-for-each-customer "The Most Frequently Ordered Products for Each Customer")
-
-## [1595. Minimum Cost to Connect Two Groups of Points (Hard)](https://leetcode.com/problems/minimum-cost-to-connect-two-groups-of-points "连通两组点的最小成本")
-
-<p>You are given two groups of points where the first group has <code>size<sub>1</sub></code> points, the second group has <code>size<sub>2</sub></code> points, and <code>size<sub>1</sub> &gt;= size<sub>2</sub></code>.</p>
-
-<p>The <code>cost</code> of the connection between any two points are given in an <code>size<sub>1</sub> x size<sub>2</sub></code> matrix where <code>cost[i][j]</code> is the cost of connecting point <code>i</code> of the first group and point <code>j</code> of the second group. The groups are connected if <strong>each point in both groups is connected to one or more points in the opposite group</strong>. In other words, each point in the first group must be connected to at least one point in the second group, and each point in the second group must be connected to at least one point in the first group.</p>
-
-<p>Return <em>the minimum cost it takes to connect the two groups</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/03/ex1.jpg" style="width: 322px; height: 243px;" />
-<pre>
-<strong>Input:</strong> cost = [[15, 96], [36, 2]]
-<strong>Output:</strong> 17
-<strong>Explanation</strong>: The optimal way of connecting the groups is:
-1--A
-2--B
-This results in a total cost of 17.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/03/ex2.jpg" style="width: 322px; height: 403px;" />
-<pre>
-<strong>Input:</strong> cost = [[1, 3, 5], [4, 1, 1], [1, 5, 3]]
-<strong>Output:</strong> 4
-<strong>Explanation</strong>: The optimal way of connecting the groups is:
-1--A
-2--B
-2--C
-3--A
-This results in a total cost of 4.
-Note that there are multiple points connected to point 2 in the first group and point A in the second group. This does not matter as there is no limit to the number of points that can be connected. We only care about the minimum total cost.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> cost = [[2, 5, 1], [3, 4, 7], [8, 1, 2], [6, 2, 4], [3, 8, 8]]
-<strong>Output:</strong> 10
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>size<sub>1</sub> == cost.length</code></li>
-	<li><code>size<sub>2</sub> == cost[i].length</code></li>
-	<li><code>1 &lt;= size<sub>1</sub>, size<sub>2</sub> &lt;= 12</code></li>
-	<li><code>size<sub>1</sub> &gt;= size<sub>2</sub></code></li>
-	<li><code>0 &lt;= cost[i][j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Each point on the left would either be connected to exactly point already connected to some left node, or a subset of the nodes on the right which are not connected to any node
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use dynamic programming with bitmasking, where the state will be (number of points assigned in first group, bitmask of points assigned in second group).
-</details>
diff --git a/problems/minimum-cost-to-cut-a-stick/README.md b/problems/minimum-cost-to-cut-a-stick/README.md
deleted file mode 100644
index 232a331a8..000000000
--- a/problems/minimum-cost-to-cut-a-stick/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-non-overlapping-subarrays-with-sum-equals-target "Maximum Number of Non-Overlapping Subarrays With Sum Equals Target")
-　　　　　　　　　　　　　　　　
-[Next >](../the-most-similar-path-in-a-graph "The Most Similar Path in a Graph")
-
-## [1547. Minimum Cost to Cut a Stick (Hard)](https://leetcode.com/problems/minimum-cost-to-cut-a-stick "切棍子的最小成本")
-
-<p>Given a wooden stick of length <code>n</code> units. The stick is labelled from <code>0</code> to <code>n</code>. For example, a stick of length <strong>6</strong> is labelled as follows:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/21/statement.jpg" style="width: 521px; height: 111px;" />
-<p>Given an integer array <code>cuts</code> where <code>cuts[i]</code> denotes a position you should perform a cut at.</p>
-
-<p>You should perform the cuts in order, you can change the order of the cuts as you wish.</p>
-
-<p>The cost of one cut is the length of the stick to be cut, the total cost is the sum of costs of all cuts. When you cut a stick, it will be split into two smaller sticks (i.e. the sum of their lengths is the length of the stick before the cut). Please refer to the first example for a better explanation.</p>
-
-<p>Return <em>the minimum total cost</em> of the cuts.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/23/e1.jpg" style="width: 350px; height: 284px;" />
-<pre>
-<strong>Input:</strong> n = 7, cuts = [1,3,4,5]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> Using cuts order = [1, 3, 4, 5] as in the input leads to the following scenario:
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/21/e11.jpg" style="width: 350px; height: 284px;" />
-The first cut is done to a rod of length 7 so the cost is 7. The second cut is done to a rod of length 6 (i.e. the second part of the first cut), the third is done to a rod of length 4 and the last cut is to a rod of length 3. The total cost is 7 + 6 + 4 + 3 = 20.
-Rearranging the cuts to be [3, 5, 1, 4] for example will lead to a scenario with total cost = 16 (as shown in the example photo 7 + 4 + 3 + 2 = 16).</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 9, cuts = [5,6,1,4,2]
-<strong>Output:</strong> 22
-<strong>Explanation:</strong> If you try the given cuts ordering the cost will be 25.
-There are much ordering with total cost &lt;= 25, for example, the order [4, 6, 5, 2, 1] has total cost = 22 which is the minimum possible.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= cuts.length &lt;= min(n - 1, 100)</code></li>
-	<li><code>1 &lt;= cuts[i] &lt;= n - 1</code></li>
-	<li>All the integers in <code>cuts</code> array are <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Number of Ways to Divide a Long Corridor](../number-of-ways-to-divide-a-long-corridor) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build a dp array where dp[i][j] is the minimum cost to achieve all the cuts between i and j.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When you try to get the minimum cost between i and j, try all possible cuts k between them, dp[i][j] = min(dp[i][k] + dp[k][j]) + (j - i) for all possible cuts k between them.
-</details>
diff --git a/problems/minimum-cost-to-hire-k-workers/README.md b/problems/minimum-cost-to-hire-k-workers/README.md
deleted file mode 100644
index 388c7e447..000000000
--- a/problems/minimum-cost-to-hire-k-workers/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../score-of-parentheses "Score of Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../mirror-reflection "Mirror Reflection")
-
-## [857. Minimum Cost to Hire K Workers (Hard)](https://leetcode.com/problems/minimum-cost-to-hire-k-workers "雇佣 K 名工人的最低成本")
-
-<p>There are <code>n</code> workers. You are given two integer arrays <code>quality</code> and <code>wage</code> where <code>quality[i]</code> is the quality of the <code>i<sup>th</sup></code> worker and <code>wage[i]</code> is the minimum wage expectation for the <code>i<sup>th</sup></code> worker.</p>
-
-<p>We want to hire exactly <code>k</code> workers to form a paid group. To hire a group of <code>k</code> workers, we must pay them according to the following rules:</p>
-
-<ol>
-	<li>Every worker in the paid group should be paid in the ratio of their quality compared to other workers in the paid group.</li>
-	<li>Every worker in the paid group must be paid at least their minimum wage expectation.</li>
-</ol>
-
-<p>Given the integer <code>k</code>, return <em>the least amount of money needed to form a paid group satisfying the above conditions</em>. Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> quality = [10,20,5], wage = [70,50,30], k = 2
-<strong>Output:</strong> 105.00000
-<strong>Explanation:</strong> We pay 70 to 0<sup>th</sup> worker and 35 to 2<sup>nd</sup> worker.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> quality = [3,1,10,10,1], wage = [4,8,2,2,7], k = 3
-<strong>Output:</strong> 30.66667
-<strong>Explanation:</strong> We pay 4 to 0<sup>th</sup> worker, 13.33333 to 2<sup>nd</sup> and 3<sup>rd</sup> workers separately.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == quality.length == wage.length</code></li>
-	<li><code>1 &lt;= k &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= quality[i], wage[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
diff --git a/problems/minimum-cost-to-hire-k-workers/minimum_cost_to_hire_k_workers.go b/problems/minimum-cost-to-hire-k-workers/minimum_cost_to_hire_k_workers.go
deleted file mode 100644
index 4a59f0940..000000000
--- a/problems/minimum-cost-to-hire-k-workers/minimum_cost_to_hire_k_workers.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem857
diff --git a/problems/minimum-cost-to-hire-k-workers/minimum_cost_to_hire_k_workers_test.go b/problems/minimum-cost-to-hire-k-workers/minimum_cost_to_hire_k_workers_test.go
deleted file mode 100644
index 4a59f0940..000000000
--- a/problems/minimum-cost-to-hire-k-workers/minimum_cost_to_hire_k_workers_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem857
diff --git a/problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid/README.md b/problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid/README.md
deleted file mode 100644
index 3a3ecc6b7..000000000
--- a/problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid/README.md
+++ /dev/null
@@ -1,96 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../linked-list-in-binary-tree "Linked List in Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../get-the-second-most-recent-activity "Get the Second Most Recent Activity")
-
-## [1368. Minimum Cost to Make at Least One Valid Path in a Grid (Hard)](https://leetcode.com/problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid "使网格图至少有一条有效路径的最小代价")
-
-Given a <em>m</em> x <em>n</em> <code>grid</code>. Each cell of the <code>grid</code> has a sign pointing to the next cell you should visit if you are currently in this cell. The sign of <code>grid[i][j]</code> can be:
-<ul>
-	<li><strong>1</strong> which means go to the cell to the right. (i.e go from <code>grid[i][j]</code> to <code>grid[i][j + 1]</code>)</li>
-	<li><strong>2</strong> which means go to the cell to the left. (i.e go from <code>grid[i][j]</code> to <code>grid[i][j - 1]</code>)</li>
-	<li><strong>3</strong> which means go to the lower cell. (i.e go from <code>grid[i][j]</code> to <code>grid[i + 1][j]</code>)</li>
-	<li><strong>4</strong> which means go to the upper cell. (i.e go from <code>grid[i][j]</code> to <code>grid[i - 1][j]</code>)</li>
-</ul>
-
-<p>Notice&nbsp;that there could be some <strong>invalid signs</strong> on the cells of the <code>grid</code> which points outside the <code>grid</code>.</p>
-
-<p>You will initially start at the upper left cell <code>(0,0)</code>. A valid path in the grid is a path which starts from the upper left&nbsp;cell <code>(0,0)</code> and ends at the bottom-right&nbsp;cell <code>(m - 1, n - 1)</code> following the signs on the grid. The valid path <strong>doesn&#39;t have to be the shortest</strong>.</p>
-
-<p>You can modify the sign on a cell with <code>cost = 1</code>. You can modify the sign on a cell <strong>one time only</strong>.</p>
-
-<p>Return <em>the minimum cost</em> to make the grid have at least one valid path.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/13/grid1.png" style="width: 542px; height: 528px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,1,1,1],[2,2,2,2],[1,1,1,1],[2,2,2,2]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You will start at point (0, 0).
-The path to (3, 3) is as follows. (0, 0) --&gt; (0, 1) --&gt; (0, 2) --&gt; (0, 3) change the arrow to down with cost = 1 --&gt; (1, 3) --&gt; (1, 2) --&gt; (1, 1) --&gt; (1, 0) change the arrow to down with cost = 1 --&gt; (2, 0) --&gt; (2, 1) --&gt; (2, 2) --&gt; (2, 3) change the arrow to down with cost = 1 --&gt; (3, 3)
-The total cost = 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/13/grid2.png" style="width: 419px; height: 408px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,1,3],[3,2,2],[1,1,4]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> You can follow the path from (0, 0) to (2, 2).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/13/grid3.png" style="width: 314px; height: 302px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,2],[4,3]]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[2,2,2],[2,2,2]]
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[4]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build a graph where grid[i][j] is connected to all the four side-adjacent cells with weighted edge. the weight is 0 if the sign is pointing to the adjacent cell or 1 otherwise.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Do BFS from (0, 0) visit all edges with weight = 0 first. the answer is the distance to (m -1, n - 1).
-</details>
diff --git a/problems/minimum-cost-to-merge-stones/README.md b/problems/minimum-cost-to-merge-stones/README.md
deleted file mode 100644
index 8efb726aa..000000000
--- a/problems/minimum-cost-to-merge-stones/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../available-captures-for-rook "Available Captures for Rook")
-　　　　　　　　　　　　　　　　
-[Next >](../grid-illumination "Grid Illumination")
-
-## [1000. Minimum Cost to Merge Stones (Hard)](https://leetcode.com/problems/minimum-cost-to-merge-stones "合并石头的最低成本")
-
-<p>There are <code>n</code> piles of <code>stones</code> arranged in a row. The <code>i<sup>th</sup></code> pile has <code>stones[i]</code> stones.</p>
-
-<p>A move consists of merging exactly <code>k</code> consecutive piles into one pile, and the cost of this move is equal to the total number of stones in these <code>k</code> piles.</p>
-
-<p>Return <em>the minimum cost to merge all piles of stones into one pile</em>. If it is impossible, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [3,2,4,1], k = 2
-<strong>Output:</strong> 20
-<strong>Explanation:</strong> We start with [3, 2, 4, 1].
-We merge [3, 2] for a cost of 5, and we are left with [5, 4, 1].
-We merge [4, 1] for a cost of 5, and we are left with [5, 5].
-We merge [5, 5] for a cost of 10, and we are left with [10].
-The total cost was 20, and this is the minimum possible.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [3,2,4,1], k = 3
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> After any merge operation, there are 2 piles left, and we can&#39;t merge anymore.  So the task is impossible.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [3,5,1,2,6], k = 3
-<strong>Output:</strong> 25
-<strong>Explanation:</strong> We start with [3, 5, 1, 2, 6].
-We merge [5, 1, 2] for a cost of 8, and we are left with [3, 8, 6].
-We merge [3, 8, 6] for a cost of 17, and we are left with [17].
-The total cost was 25, and this is the minimum possible.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == stones.length</code></li>
-	<li><code>1 &lt;= n &lt;= 30</code></li>
-	<li><code>1 &lt;= stones[i] &lt;= 100</code></li>
-	<li><code>2 &lt;= k &lt;= 30</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Burst Balloons](../burst-balloons) (Hard)
-  1. [Minimum Cost to Connect Sticks](../minimum-cost-to-connect-sticks) (Medium)
diff --git a/problems/minimum-cost-to-merge-stones/minimum_cost_to_merge_stones.go b/problems/minimum-cost-to-merge-stones/minimum_cost_to_merge_stones.go
deleted file mode 100644
index f6499d0cd..000000000
--- a/problems/minimum-cost-to-merge-stones/minimum_cost_to_merge_stones.go
+++ /dev/null
@@ -1,48 +0,0 @@
-package problem1000
-
-func mergeStones(stones []int, K int) int {
-	size := len(stones)
-	if (size-1)%(K-1) != 0 {
-		return -1
-	}
-
-	sum := [31]int{}
-	for i := 0; i < size; i++ {
-		sum[i+1] = sum[i] + stones[i]
-	}
-
-	dp := [31][31]int{}
-	// dp[l][r] 的含义是，
-	//   stones[l:r+1] 完成**所有**合并后，所花费的最小费用。
-	// 我着重强调了 **所有** 二字
-	// dp[l][r] 在完成所有合并后，有两种可能
-	//    1.     合并成一块石头
-	//    2. 没有合并成一块石头
-
-	for width := K; width <= size; width++ {
-		for l := 0; l+width <= size; l++ {
-			r := l + width - 1
-			dp[l][r] = 1 << 32
-			for m := l; m < r; m += K - 1 {
-				dp[l][r] = min(dp[l][r], dp[l][m]+dp[m+1][r])
-				// 把 dp[l][r] 分解成两个部分
-				//     dp[l][m]   代表了，能合并成一块石头的左边，
-				//     dp[m+1][r] 代表了，剩下的右边。
-			}
-			if (r-l)%(K-1) == 0 {
-				// 如果 dp[l][r] 的左边和右边还能够进行合并
-				// 还要加上最后一次合并的费用
-				dp[l][r] += sum[r+1] - sum[l]
-			}
-		}
-	}
-
-	return dp[0][size-1]
-}
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
diff --git a/problems/minimum-cost-to-move-chips-to-the-same-position/README.md b/problems/minimum-cost-to-move-chips-to-the-same-position/README.md
deleted file mode 100644
index 66e1937ff..000000000
--- a/problems/minimum-cost-to-move-chips-to-the-same-position/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-palindrome-iii "Valid Palindrome III")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-arithmetic-subsequence-of-given-difference "Longest Arithmetic Subsequence of Given Difference")
-
-## [1217. Minimum Cost to Move Chips to The Same Position (Easy)](https://leetcode.com/problems/minimum-cost-to-move-chips-to-the-same-position "玩筹码")
-
-<p>We have <code>n</code> chips, where the position of the <code>i<sup>th</sup></code> chip is <code>position[i]</code>.</p>
-
-<p>We need to move all the chips to <strong>the same position</strong>. In one step, we can change the position of the <code>i<sup>th</sup></code> chip from <code>position[i]</code> to:</p>
-
-<ul>
-	<li><code>position[i] + 2</code> or <code>position[i] - 2</code> with <code>cost = 0</code>.</li>
-	<li><code>position[i] + 1</code> or <code>position[i] - 1</code> with <code>cost = 1</code>.</li>
-</ul>
-
-<p>Return <em>the minimum cost</em> needed to move all the chips to the same position.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/15/chips_e1.jpg" style="width: 750px; height: 217px;" />
-<pre>
-<strong>Input:</strong> position = [1,2,3]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> First step: Move the chip at position 3 to position 1 with cost = 0.
-Second step: Move the chip at position 2 to position 1 with cost = 1.
-Total cost is 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/15/chip_e2.jpg" style="width: 750px; height: 306px;" />
-<pre>
-<strong>Input:</strong> position = [2,2,2,3,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We can move the two chips at position  3 to position 2. Each move has cost = 1. The total cost = 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> position = [1,1000000000]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= position.length &lt;= 100</code></li>
-	<li><code>1 &lt;= position[i] &lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Minimum Number of Operations to Move All Balls to Each Box](../minimum-number-of-operations-to-move-all-balls-to-each-box) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The first move keeps the parity of the element as it is.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The second move changes the parity of the element.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Since the first move is free, if all the numbers have the same parity, the answer would be zero.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Find the minimum cost to make all the numbers have the same parity.
-</details>
diff --git a/problems/minimum-cost-to-reach-city-with-discounts/README.md b/problems/minimum-cost-to-reach-city-with-discounts/README.md
deleted file mode 100644
index 873df6d98..000000000
--- a/problems/minimum-cost-to-reach-city-with-discounts/README.md
+++ /dev/null
@@ -1,34 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-all-people-with-secret "Find All People With Secret")
-　　　　　　　　　　　　　　　　
-[Next >](../finding-3-digit-even-numbers "Finding 3-Digit Even Numbers")
-
-## [2093. Minimum Cost to Reach City With Discounts (Medium)](https://leetcode.com/problems/minimum-cost-to-reach-city-with-discounts "")
-
-
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to construct a graph out of highways. What type of graph is this?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We essentially need to find the minimum distance to get from node 0 to node n - 1 in an undirected weighted graph. What algorithm should we use to do this?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use Dijkstra's algorithm to find the minimum weight path. Keep track of the minimum distance to each vertex with d discounts left
-</details>
diff --git a/problems/minimum-cost-to-reach-destination-in-time/README.md b/problems/minimum-cost-to-reach-destination-in-time/README.md
deleted file mode 100644
index d2bc9797e..000000000
--- a/problems/minimum-cost-to-reach-destination-in-time/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-game "Sum Game")
-　　　　　　　　　　　　　　　　
-[Next >](../concatenation-of-array "Concatenation of Array")
-
-## [1928. Minimum Cost to Reach Destination in Time (Hard)](https://leetcode.com/problems/minimum-cost-to-reach-destination-in-time "规定时间内到达终点的最小花费")
-
-<p>There is a country of <code>n</code> cities numbered from <code>0</code> to <code>n - 1</code> where <strong>all the cities are connected</strong> by bi-directional roads. The roads are represented as a 2D integer array <code>edges</code> where <code>edges[i] = [x<sub>i</sub>, y<sub>i</sub>, time<sub>i</sub>]</code> denotes a road between cities <code>x<sub>i</sub></code> and <code>y<sub>i</sub></code> that takes <code>time<sub>i</sub></code> minutes to travel. There may be multiple roads of differing travel times connecting the same two cities, but no road connects a city to itself.</p>
-
-<p>Each time you pass through a city, you must pay a passing fee. This is represented as a <strong>0-indexed</strong> integer array <code>passingFees</code> of length <code>n</code> where <code>passingFees[j]</code> is the amount of dollars you must pay when you pass through city <code>j</code>.</p>
-
-<p>In the beginning, you are at city <code>0</code> and want to reach city <code>n - 1</code> in <code>maxTime</code><strong> minutes or less</strong>. The <strong>cost</strong> of your journey is the <strong>summation of passing fees</strong> for each city that you passed through at some moment of your journey (<strong>including</strong> the source and destination cities).</p>
-
-<p>Given <code>maxTime</code>, <code>edges</code>, and <code>passingFees</code>, return <em>the <strong>minimum cost</strong> to complete your journey, or </em><code>-1</code><em> if you cannot complete it within </em><code>maxTime</code><em> minutes</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/06/04/leetgraph1-1.png" style="width: 371px; height: 171px;" /></p>
-
-<pre>
-<strong>Input:</strong> maxTime = 30, edges = [[0,1,10],[1,2,10],[2,5,10],[0,3,1],[3,4,10],[4,5,15]], passingFees = [5,1,2,20,20,3]
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> The path to take is 0 -&gt; 1 -&gt; 2 -&gt; 5, which takes 30 minutes and has $11 worth of passing fees.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2021/06/04/copy-of-leetgraph1-1.png" style="width: 371px; height: 171px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> maxTime = 29, edges = [[0,1,10],[1,2,10],[2,5,10],[0,3,1],[3,4,10],[4,5,15]], passingFees = [5,1,2,20,20,3]
-<strong>Output:</strong> 48
-<strong>Explanation:</strong> The path to take is 0 -&gt; 3 -&gt; 4 -&gt; 5, which takes 26 minutes and has $48 worth of passing fees.
-You cannot take path 0 -&gt; 1 -&gt; 2 -&gt; 5 since it would take too long.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> maxTime = 25, edges = [[0,1,10],[1,2,10],[2,5,10],[0,3,1],[3,4,10],[4,5,15]], passingFees = [5,1,2,20,20,3]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There is no way to reach city 5 from city 0 within 25 minutes.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= maxTime &lt;= 1000</code></li>
-	<li><code>n == passingFees.length</code></li>
-	<li><code>2 &lt;= n &lt;= 1000</code></li>
-	<li><code>n - 1 &lt;= edges.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>1 &lt;= time<sub>i</sub> &lt;= 1000</code></li>
-	<li><code>1 &lt;= passingFees[j] &lt;= 1000</code>&nbsp;</li>
-	<li>The graph may contain multiple edges between two nodes.</li>
-	<li>The graph does not contain self loops.</li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [Maximum Path Quality of a Graph](../maximum-path-quality-of-a-graph) (Hard)
-  1. [Minimum Cost to Reach City With Discounts](../minimum-cost-to-reach-city-with-discounts) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider a new graph where each node is one of the old nodes at a specific time. For example, node 0 at time 5.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You need to find the shortest path in the new graph.
-</details>
diff --git a/problems/minimum-cost-to-separate-sentence-into-rows/README.md b/problems/minimum-cost-to-separate-sentence-into-rows/README.md
deleted file mode 100644
index 559bc0df4..000000000
--- a/problems/minimum-cost-to-separate-sentence-into-rows/README.md
+++ /dev/null
@@ -1,34 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-category-of-each-member-in-the-store "The Category of Each Member in the Store")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-distinct-string-in-an-array "Kth Distinct String in an Array")
-
-## [2052. Minimum Cost to Separate Sentence Into Rows (Medium)](https://leetcode.com/problems/minimum-cost-to-separate-sentence-into-rows "将句子分隔成行的最低成本")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create an array storing all of the words in sentence separated.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try dynamic programming.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Build a dp array where dp[i] represents the minimum total cost for the first i + 1 words.
-</details>
diff --git a/problems/minimum-cost-to-set-cooking-time/README.md b/problems/minimum-cost-to-set-cooking-time/README.md
deleted file mode 100644
index c3235cd38..000000000
--- a/problems/minimum-cost-to-set-cooking-time/README.md
+++ /dev/null
@@ -1,98 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partition-array-according-to-given-pivot "Partition Array According to Given Pivot")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-difference-in-sums-after-removal-of-elements "Minimum Difference in Sums After Removal of Elements")
-
-## [2162. Minimum Cost to Set Cooking Time (Medium)](https://leetcode.com/problems/minimum-cost-to-set-cooking-time "设置时间的最少代价")
-
-<p>A generic microwave supports cooking times for:</p>
-
-<ul>
-	<li>at least <code>1</code> second.</li>
-	<li>at most <code>99</code> minutes and <code>99</code> seconds.</li>
-</ul>
-
-<p>To set the cooking time, you push <strong>at most four digits</strong>. The microwave normalizes what you push as four digits by <strong>prepending zeroes</strong>. It interprets the <strong>first</strong> two digits as the minutes and the <strong>last</strong> two digits as the seconds. It then <strong>adds</strong> them up as the cooking time. For example,</p>
-
-<ul>
-	<li>You push <code>9</code> <code>5</code> <code>4</code> (three digits). It is normalized as <code>0954</code> and interpreted as <code>9</code> minutes and <code>54</code> seconds.</li>
-	<li>You push <code>0</code> <code>0</code> <code>0</code> <code>8</code> (four digits). It is interpreted as <code>0</code> minutes and <code>8</code> seconds.</li>
-	<li>You push <code>8</code> <code>0</code> <code>9</code> <code>0</code>. It is interpreted as <code>80</code> minutes and <code>90</code> seconds.</li>
-	<li>You push <code>8</code> <code>1</code> <code>3</code> <code>0</code>. It is interpreted as <code>81</code> minutes and <code>30</code> seconds.</li>
-</ul>
-
-<p>You are given integers <code>startAt</code>, <code>moveCost</code>, <code>pushCost</code>, and <code>targetSeconds</code>. <strong>Initially</strong>, your finger is on the digit <code>startAt</code>. Moving the finger above <strong>any specific digit</strong> costs <code>moveCost</code> units of fatigue. Pushing the digit below the finger <strong>once</strong> costs <code>pushCost</code> units of fatigue.</p>
-
-<p>There can be multiple ways to set the microwave to cook for <code>targetSeconds</code> seconds but you are interested in the way with the minimum cost.</p>
-
-<p>Return <em>the <strong>minimum cost</strong> to set</em> <code>targetSeconds</code> <em>seconds of cooking time</em>.</p>
-
-<p>Remember that one minute consists of <code>60</code> seconds.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/30/1.png" style="width: 506px; height: 210px;" />
-<pre>
-<strong>Input:</strong> startAt = 1, moveCost = 2, pushCost = 1, targetSeconds = 600
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The following are the possible ways to set the cooking time.
-- 1 0 0 0, interpreted as 10 minutes and 0 seconds.
-&nbsp; The finger is already on digit 1, pushes 1 (with cost 1), moves to 0 (with cost 2), pushes 0 (with cost 1), pushes 0 (with cost 1), and pushes 0 (with cost 1).
-&nbsp; The cost is: 1 + 2 + 1 + 1 + 1 = 6. This is the minimum cost.
-- 0 9 6 0, interpreted as 9 minutes and 60 seconds. That is also 600 seconds.
-&nbsp; The finger moves to 0 (with cost 2), pushes 0 (with cost 1), moves to 9 (with cost 2), pushes 9 (with cost 1), moves to 6 (with cost 2), pushes 6 (with cost 1), moves to 0 (with cost 2), and pushes 0 (with cost 1).
-&nbsp; The cost is: 2 + 1 + 2 + 1 + 2 + 1 + 2 + 1 = 12.
-- 9 6 0, normalized as 0960 and interpreted as 9 minutes and 60 seconds.
-&nbsp; The finger moves to 9 (with cost 2), pushes 9 (with cost 1), moves to 6 (with cost 2), pushes 6 (with cost 1), moves to 0 (with cost 2), and pushes 0 (with cost 1).
-&nbsp; The cost is: 2 + 1 + 2 + 1 + 2 + 1 = 9.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/30/2.png" style="width: 505px; height: 73px;" />
-<pre>
-<strong>Input:</strong> startAt = 0, moveCost = 1, pushCost = 2, targetSeconds = 76
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The optimal way is to push two digits: 7 6, interpreted as 76 seconds.
-The finger moves to 7 (with cost 1), pushes 7 (with cost 2), moves to 6 (with cost 1), and pushes 6 (with cost 2). The total cost is: 1 + 2 + 1 + 2 = 6
-Note other possible ways are 0076, 076, 0116, and 116, but none of them produces the minimum cost.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= startAt &lt;= 9</code></li>
-	<li><code>1 &lt;= moveCost, pushCost &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= targetSeconds &lt;= 6039</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Define a separate function Cost(mm, ss) where 0 <= mm <= 99 and 0 <= ss <= 99. This function should calculate the cost of setting the cocking time to mm minutes and ss seconds
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The range of the minutes is small (i.e., [0, 99]), how can you use that?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For every mm in [0, 99], calculate the needed ss to make mm:ss equal to targetSeconds and minimize the cost of setting the cocking time to mm:ss
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Be careful in some cases when ss is not in the valid range [0, 99].
-</details>
diff --git a/problems/minimum-cost-tree-from-leaf-values/README.md b/problems/minimum-cost-tree-from-leaf-values/README.md
deleted file mode 100644
index 35cd83444..000000000
--- a/problems/minimum-cost-tree-from-leaf-values/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-path-with-alternating-colors "Shortest Path with Alternating Colors")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-of-absolute-value-expression "Maximum of Absolute Value Expression")
-
-## [1130. Minimum Cost Tree From Leaf Values (Medium)](https://leetcode.com/problems/minimum-cost-tree-from-leaf-values "叶值的最小代价生成树")
-
-<p>Given an array <code>arr</code> of positive integers, consider all binary trees such that:</p>
-
-<ul>
-	<li>Each node has either <code>0</code> or <code>2</code> children;</li>
-	<li>The values of <code>arr</code> correspond to the values of each <strong>leaf</strong> in an in-order traversal of the tree.</li>
-	<li>The value of each non-leaf node is equal to the product of the largest leaf value in its left and right subtree, respectively.</li>
-</ul>
-
-<p>Among all possible binary trees considered, return <em>the smallest possible sum of the values of each non-leaf node</em>. It is guaranteed this sum fits into a <strong>32-bit</strong> integer.</p>
-
-<p>A node is a <strong>leaf</strong> if and only if it has zero children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/10/tree1.jpg" style="width: 500px; height: 169px;" />
-<pre>
-<strong>Input:</strong> arr = [6,2,4]
-<strong>Output:</strong> 32
-<strong>Explanation:</strong> There are two possible trees shown.
-The first has a non-leaf node sum 36, and the second has non-leaf node sum 32.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/10/tree2.jpg" style="width: 224px; height: 145px;" />
-<pre>
-<strong>Input:</strong> arr = [4,11]
-<strong>Output:</strong> 44
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr.length &lt;= 40</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 15</code></li>
-	<li>It is guaranteed that the answer fits into a <strong>32-bit</strong> signed integer (i.e., it is less than 2<sup>31</sup>).</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do a DP, where dp(i, j) is the answer for the subarray arr[i]..arr[j].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each possible way to partition the subarray i <= k < j, the answer is max(arr[i]..arr[k]) * max(arr[k+1]..arr[j]) + dp(i, k) + dp(k+1, j).
-</details>
diff --git a/problems/minimum-degree-of-a-connected-trio-in-a-graph/README.md b/problems/minimum-degree-of-a-connected-trio-in-a-graph/README.md
deleted file mode 100644
index 039af768b..000000000
--- a/problems/minimum-degree-of-a-connected-trio-in-a-graph/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-limit-of-balls-in-a-bag "Minimum Limit of Balls in a Bag")
-　　　　　　　　　　　　　　　　
-[Next >](../buildings-with-an-ocean-view "Buildings With an Ocean View")
-
-## [1761. Minimum Degree of a Connected Trio in a Graph (Hard)](https://leetcode.com/problems/minimum-degree-of-a-connected-trio-in-a-graph "一个图中连通三元组的最小度数")
-
-<p>You are given an undirected graph. You are given an integer <code>n</code> which is the number of nodes in the graph and an array <code>edges</code>, where each <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> indicates that there is an undirected edge between <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code>.</p>
-
-<p>A <strong>connected trio</strong> is a set of <strong>three</strong> nodes where there is an edge between <b>every</b> pair of them.</p>
-
-<p>The <strong>degree of a connected trio</strong> is the number of edges where one endpoint is in the trio, and the other is not.</p>
-
-<p>Return <em>the <strong>minimum</strong> degree of a connected trio in the graph, or</em> <code>-1</code> <em>if the graph has no connected trios.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/26/trios1.png" style="width: 388px; height: 164px;" />
-<pre>
-<strong>Input:</strong> n = 6, edges = [[1,2],[1,3],[3,2],[4,1],[5,2],[3,6]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> There is exactly one trio, which is [1,2,3]. The edges that form its degree are bolded in the figure above.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/26/trios2.png" style="width: 388px; height: 164px;" />
-<pre>
-<strong>Input:</strong> n = 7, edges = [[1,3],[4,1],[4,3],[2,5],[5,6],[6,7],[7,5],[2,6]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are exactly three trios:
-1) [1,4,3] with degree 0.
-2) [2,5,6] with degree 2.
-3) [5,6,7] with degree 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 400</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>1 &lt;= edges.length &lt;= n * (n-1) / 2</code></li>
-	<li><code>1 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n</code></li>
-	<li><code>u<sub>i </sub>!= v<sub>i</sub></code></li>
-	<li>There are no repeated edges.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider a trio with nodes u, v, and w. The degree of the trio is just degree(u) + degree(v) + degree(w) - 6. The -6 comes from subtracting the edges u-v, u-w, and v-w, which are counted twice each in the vertex degree calculation.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To get the trios (u,v,w), you can iterate on u, then iterate on each w,v such that w and v are neighbors of u and are neighbors of each other.
-</details>
diff --git a/problems/minimum-deletion-cost-to-avoid-repeating-letters/README.md b/problems/minimum-deletion-cost-to-avoid-repeating-letters/README.md
deleted file mode 100644
index 7bcb7dda0..000000000
--- a/problems/minimum-deletion-cost-to-avoid-repeating-letters/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers "Number of Ways Where Square of Number Is Equal to Product of Two Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-max-number-of-edges-to-keep-graph-fully-traversable "Remove Max Number of Edges to Keep Graph Fully Traversable")
-
-## [1578. Minimum Deletion Cost to Avoid Repeating Letters (Medium)](https://leetcode.com/problems/minimum-deletion-cost-to-avoid-repeating-letters "避免重复字母的最小删除成本")
-
-<p>Given a&nbsp;string <code>s</code> and an array of integers <code>cost</code> where <code>cost[i]</code>&nbsp;is the cost of deleting the <code>i<sup>th</sup></code> character in <code>s</code>.</p>
-
-<p>Return the minimum cost of deletions such that there are no two identical letters next to each other.</p>
-
-<p>Notice that you will delete the chosen characters at the same time, in other words, after deleting a character, the costs of deleting other characters will not change.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abaac&quot;, cost = [1,2,3,4,5]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Delete the letter &quot;a&quot; with cost 3 to get &quot;abac&quot; (String without two identical letters next to each other).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;, cost = [1,2,3]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> You don&#39;t need to delete any character because there are no identical letters next to each other.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabaa&quot;, cost = [1,2,3,4,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Delete the first and the last character, getting the string (&quot;aba&quot;).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>s.length == cost.length</code></li>
-	<li><code>1 &lt;= s.length, cost.length &lt;= 10^5</code></li>
-	<li><code>1 &lt;= cost[i] &lt;=&nbsp;10^4</code></li>
-	<li><code>s</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Maintain the running sum and max value for repeated letters.
-</details>
diff --git a/problems/minimum-deletions-to-make-character-frequencies-unique/README.md b/problems/minimum-deletions-to-make-character-frequencies-unique/README.md
deleted file mode 100644
index 3fdb2db07..000000000
--- a/problems/minimum-deletions-to-make-character-frequencies-unique/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../get-maximum-in-generated-array "Get Maximum in Generated Array")
-　　　　　　　　　　　　　　　　
-[Next >](../sell-diminishing-valued-colored-balls "Sell Diminishing-Valued Colored Balls")
-
-## [1647. Minimum Deletions to Make Character Frequencies Unique (Medium)](https://leetcode.com/problems/minimum-deletions-to-make-character-frequencies-unique "字符频次唯一的最小删除次数")
-
-<p>A string <code>s</code> is called <strong>good</strong> if there are no two different characters in <code>s</code> that have the same <strong>frequency</strong>.</p>
-
-<p>Given a string <code>s</code>, return<em> the <strong>minimum</strong> number of characters you need to delete to make </em><code>s</code><em> <strong>good</strong>.</em></p>
-
-<p>The <strong>frequency</strong> of a character in a string is the number of times it appears in the string. For example, in the string <code>&quot;aab&quot;</code>, the <strong>frequency</strong> of <code>&#39;a&#39;</code> is <code>2</code>, while the <strong>frequency</strong> of <code>&#39;b&#39;</code> is <code>1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aab&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> <code>s</code> is already good.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaabbbcc&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You can delete two &#39;b&#39;s resulting in the good string &quot;aaabcc&quot;.
-Another way it to delete one &#39;b&#39; and one &#39;c&#39; resulting in the good string &quot;aaabbc&quot;.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ceabaacb&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You can delete both &#39;c&#39;s resulting in the good string &quot;eabaab&quot;.
-Note that we only care about characters that are still in the string at the end (i.e. frequency of 0 is ignored).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code>&nbsp;contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-As we can only delete characters, if we have multiple characters having the same frequency, we must decrease all the frequencies of them, except one.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort the alphabet characters by their frequencies non-increasingly.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Iterate on the alphabet characters, keep decreasing the frequency of the current character until it reaches a value that has not appeared before.
-</details>
diff --git a/problems/minimum-deletions-to-make-string-balanced/README.md b/problems/minimum-deletions-to-make-string-balanced/README.md
deleted file mode 100644
index 32083314e..000000000
--- a/problems/minimum-deletions-to-make-string-balanced/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../defuse-the-bomb "Defuse the Bomb")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-jumps-to-reach-home "Minimum Jumps to Reach Home")
-
-## [1653. Minimum Deletions to Make String Balanced (Medium)](https://leetcode.com/problems/minimum-deletions-to-make-string-balanced "使字符串平衡的最少删除次数")
-
-<p>You are given a string <code>s</code> consisting only of characters <code>&#39;a&#39;</code> and <code>&#39;b&#39;</code>​​​​.</p>
-
-<p>You can delete any number of characters in <code>s</code> to make <code>s</code> <strong>balanced</strong>. <code>s</code> is <strong>balanced</strong> if there is no pair of indices <code>(i,j)</code> such that <code>i &lt; j</code> and <code>s[i] = &#39;b&#39;</code> and <code>s[j]= &#39;a&#39;</code>.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of deletions needed to make </em><code>s</code><em> <strong>balanced</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aababbab&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You can either:
-Delete the characters at 0-indexed positions 2 and 6 (&quot;aa<u>b</u>abb<u>a</u>b&quot; -&gt; &quot;aaabbb&quot;), or
-Delete the characters at 0-indexed positions 3 and 6 (&quot;aab<u>a</u>bb<u>a</u>b&quot; -&gt; &quot;aabbbb&quot;).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bbaaaaabb&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The only solution is to delete the first two characters.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is&nbsp;<code>&#39;a&#39;</code> or <code>&#39;b&#39;</code>​​.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-
-### Similar Questions
-  1. [Check if All A's Appears Before All B's](../check-if-all-as-appears-before-all-bs) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You need to find for every index the number of Bs before it and the number of A's after it
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can speed up the finding of A's and B's in suffix and prefix using preprocessing
-</details>
diff --git a/problems/minimum-depth-of-binary-tree/README.md b/problems/minimum-depth-of-binary-tree/README.md
deleted file mode 100644
index 890e8b2ea..000000000
--- a/problems/minimum-depth-of-binary-tree/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../balanced-binary-tree "Balanced Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../path-sum "Path Sum")
-
-## [111. Minimum Depth of Binary Tree (Easy)](https://leetcode.com/problems/minimum-depth-of-binary-tree "二叉树的最小深度")
-
-<p>Given a binary tree, find its minimum depth.</p>
-
-<p>The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.</p>
-
-<p><strong>Note:</strong>&nbsp;A leaf is a node with no children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/12/ex_depth.jpg" style="width: 432px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,null,null,15,7]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [2,null,3,null,4,null,5,null,6]
-<strong>Output:</strong> 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>5</sup>]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Level Order Traversal](../binary-tree-level-order-traversal) (Medium)
-  1. [Maximum Depth of Binary Tree](../maximum-depth-of-binary-tree) (Easy)
diff --git a/problems/minimum-depth-of-binary-tree/minimum_depth_of_binary_tree.go b/problems/minimum-depth-of-binary-tree/minimum_depth_of_binary_tree.go
deleted file mode 100644
index b1fd97022..000000000
--- a/problems/minimum-depth-of-binary-tree/minimum_depth_of_binary_tree.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem111
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func minDepth(root *TreeNode) int {
-	if root == nil {
-		return 0
-	}
-	l := minDepth(root.Left)
-	r := minDepth(root.Right)
-	if l == 0 || r == 0 {
-		return l + r + 1
-	}
-	if l < r {
-		return l + 1
-	}
-	return r + 1
-}
diff --git a/problems/minimum-depth-of-binary-tree/minimum_depth_of_binary_tree_test.go b/problems/minimum-depth-of-binary-tree/minimum_depth_of_binary_tree_test.go
deleted file mode 100644
index 9d7a07899..000000000
--- a/problems/minimum-depth-of-binary-tree/minimum_depth_of_binary_tree_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem111
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMinDepth(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 9, 20, kit.NULL, kit.NULL, 15, 7},
-			want: 2,
-		},
-		{
-			in:   []int{1, 2},
-			want: 2,
-		},
-		{
-			in:   nil,
-			want: 0,
-		},
-	}
-	for _, tt := range tests {
-		got := minDepth(kit.SliceInt2TreeNode(tt.in))
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/minimum-difference-between-highest-and-lowest-of-k-scores/README.md b/problems/minimum-difference-between-highest-and-lowest-of-k-scores/README.md
deleted file mode 100644
index f53074997..000000000
--- a/problems/minimum-difference-between-highest-and-lowest-of-k-scores/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../widest-pair-of-indices-with-equal-range-sum "Widest Pair of Indices With Equal Range Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-kth-largest-integer-in-the-array "Find the Kth Largest Integer in the Array")
-
-## [1984. Minimum Difference Between Highest and Lowest of K Scores (Easy)](https://leetcode.com/problems/minimum-difference-between-highest-and-lowest-of-k-scores "学生分数的最小差值")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code>, where <code>nums[i]</code> represents the score of the <code>i<sup>th</sup></code> student. You are also given an integer <code>k</code>.</p>
-
-<p>Pick the scores of any <code>k</code> students from the array so that the <strong>difference</strong> between the <strong>highest</strong> and the <strong>lowest</strong> of the <code>k</code> scores is <strong>minimized</strong>.</p>
-
-<p>Return <em>the <strong>minimum</strong> possible difference</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [90], k = 1
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is one way to pick score(s) of one student:
-- [<strong><u>90</u></strong>]. The difference between the highest and lowest score is 90 - 90 = 0.
-The minimum possible difference is 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,4,1,7], k = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are six ways to pick score(s) of two students:
-- [<strong><u>9</u></strong>,<strong><u>4</u></strong>,1,7]. The difference between the highest and lowest score is 9 - 4 = 5.
-- [<strong><u>9</u></strong>,4,<strong><u>1</u></strong>,7]. The difference between the highest and lowest score is 9 - 1 = 8.
-- [<strong><u>9</u></strong>,4,1,<strong><u>7</u></strong>]. The difference between the highest and lowest score is 9 - 7 = 2.
-- [9,<strong><u>4</u></strong>,<strong><u>1</u></strong>,7]. The difference between the highest and lowest score is 4 - 1 = 3.
-- [9,<strong><u>4</u></strong>,1,<strong><u>7</u></strong>]. The difference between the highest and lowest score is 7 - 4 = 3.
-- [9,4,<strong><u>1</u></strong>,<strong><u>7</u></strong>]. The difference between the highest and lowest score is 7 - 1 = 6.
-The minimum possible difference is 2.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For the difference between the highest and lowest element to be minimized, the k chosen scores need to be as close to each other as possible.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What if the array was sorted?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-After sorting the scores, any contiguous k scores are as close to each other as possible.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Apply a sliding window solution to iterate over each contiguous k scores, and find the minimum of the differences of all windows.
-</details>
diff --git a/problems/minimum-difference-between-largest-and-smallest-value-in-three-moves/README.md b/problems/minimum-difference-between-largest-and-smallest-value-in-three-moves/README.md
deleted file mode 100644
index 4c51853a1..000000000
--- a/problems/minimum-difference-between-largest-and-smallest-value-in-three-moves/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-sum-of-sorted-subarray-sums "Range Sum of Sorted Subarray Sums")
-　　　　　　　　　　　　　　　　
-[Next >](../stone-game-iv "Stone Game IV")
-
-## [1509. Minimum Difference Between Largest and Smallest Value in Three Moves (Medium)](https://leetcode.com/problems/minimum-difference-between-largest-and-smallest-value-in-three-moves "三次操作后最大值与最小值的最小差")
-
-<p>You are given an integer array <code>nums</code>. In one move, you can choose one element of <code>nums</code> and change it by <strong>any value</strong>.</p>
-
-<p>Return <em>the minimum difference between the largest and smallest value of <code>nums</code> after performing <strong>at most three moves</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,3,2,4]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Change the array [5,3,2,4] to [<strong>2</strong>,<strong>2</strong>,2,<strong>2</strong>].
-The difference between the maximum and minimum is 2-2 = 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5,0,10,14]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Change the array [1,5,0,10,14] to [1,<strong>1</strong>,0,<strong>1</strong>,<strong>1</strong>]. 
-The difference between the maximum and minimum is 1-0 = 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The minimum difference possible is is obtained by removing 3 elements between the 3 smallest  and 3 largest values in the array.
-</details>
diff --git a/problems/minimum-difference-in-sums-after-removal-of-elements/README.md b/problems/minimum-difference-in-sums-after-removal-of-elements/README.md
deleted file mode 100644
index 9daf25991..000000000
--- a/problems/minimum-difference-in-sums-after-removal-of-elements/README.md
+++ /dev/null
@@ -1,90 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-set-cooking-time "Minimum Cost to Set Cooking Time")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-even-and-odd-indices-independently "Sort Even and Odd Indices Independently")
-
-## [2163. Minimum Difference in Sums After Removal of Elements (Hard)](https://leetcode.com/problems/minimum-difference-in-sums-after-removal-of-elements "删除元素后和的最小差值")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code> consisting of <code>3 * n</code> elements.</p>
-
-<p>You are allowed to remove any <strong>subsequence</strong> of elements of size <strong>exactly</strong> <code>n</code> from <code>nums</code>. The remaining <code>2 * n</code> elements will be divided into two <strong>equal</strong> parts:</p>
-
-<ul>
-	<li>The first <code>n</code> elements belonging to the first part and their sum is <code>sum<sub>first</sub></code>.</li>
-	<li>The next <code>n</code> elements belonging to the second part and their sum is <code>sum<sub>second</sub></code>.</li>
-</ul>
-
-<p>The <strong>difference in sums</strong> of the two parts is denoted as <code>sum<sub>first</sub> - sum<sub>second</sub></code>.</p>
-
-<ul>
-	<li>For example, if <code>sum<sub>first</sub> = 3</code> and <code>sum<sub>second</sub> = 2</code>, their difference is <code>1</code>.</li>
-	<li>Similarly, if <code>sum<sub>first</sub> = 2</code> and <code>sum<sub>second</sub> = 3</code>, their difference is <code>-1</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum difference</strong> possible between the sums of the two parts after the removal of </em><code>n</code><em> elements</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,2]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> Here, nums has 3 elements, so n = 1. 
-Thus we have to remove 1 element from nums and divide the array into two equal parts.
-- If we remove nums[0] = 3, the array will be [1,2]. The difference in sums of the two parts will be 1 - 2 = -1.
-- If we remove nums[1] = 1, the array will be [3,2]. The difference in sums of the two parts will be 3 - 2 = 1.
-- If we remove nums[2] = 2, the array will be [3,1]. The difference in sums of the two parts will be 3 - 1 = 2.
-The minimum difference between sums of the two parts is min(-1,1,2) = -1. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,9,5,8,1,3]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Here n = 2. So we must remove 2 elements and divide the remaining array into two parts containing two elements each.
-If we remove nums[2] = 5 and nums[3] = 8, the resultant array will be [7,9,1,3]. The difference in sums will be (7+9) - (1+3) = 12.
-To obtain the minimum difference, we should remove nums[1] = 9 and nums[4] = 1. The resultant array becomes [7,5,8,3]. The difference in sums of the two parts is (7+5) - (8+3) = 1.
-It can be shown that it is not possible to obtain a difference smaller than 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>nums.length == 3 * n</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The lowest possible difference can be obtained when the sum of the first n elements in the resultant array is minimum, and the sum of the next n elements is maximum.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For every index i, think about how you can find the minimum possible sum of n elements with indices lesser or equal to i, if possible.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Similarly, for every index i, try to find the maximum possible sum of n elements with indices greater or equal to i, if possible.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Now for all indices, check if we can consider it as the partitioning index and hence find the answer.
-</details>
diff --git a/problems/minimum-difficulty-of-a-job-schedule/README.md b/problems/minimum-difficulty-of-a-job-schedule/README.md
deleted file mode 100644
index 7367d9f71..000000000
--- a/problems/minimum-difficulty-of-a-job-schedule/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance "Find the City With the Smallest Number of Neighbors at a Threshold Distance")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-transactions-per-visit "Number of Transactions per Visit")
-
-## [1335. Minimum Difficulty of a Job Schedule (Hard)](https://leetcode.com/problems/minimum-difficulty-of-a-job-schedule "工作计划的最低难度")
-
-<p>You want to schedule a list of jobs in <code>d</code> days. Jobs are dependent (i.e To work on the <code>i<sup>th</sup></code> job, you have to finish all the jobs <code>j</code> where <code>0 &lt;= j &lt; i</code>).</p>
-
-<p>You have to finish <strong>at least</strong> one task every day. The difficulty of a job schedule is the sum of difficulties of each day of the <code>d</code> days. The difficulty of a day is the maximum difficulty of a job done on that day.</p>
-
-<p>You are given an integer array <code>jobDifficulty</code> and an integer <code>d</code>. The difficulty of the <code>i<sup>th</sup></code> job is <code>jobDifficulty[i]</code>.</p>
-
-<p>Return <em>the minimum difficulty of a job schedule</em>. If you cannot find a schedule for the jobs return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/16/untitled.png" style="width: 365px; height: 370px;" />
-<pre>
-<strong>Input:</strong> jobDifficulty = [6,5,4,3,2,1], d = 2
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> First day you can finish the first 5 jobs, total difficulty = 6.
-Second day you can finish the last job, total difficulty = 1.
-The difficulty of the schedule = 6 + 1 = 7 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> jobDifficulty = [9,9,9], d = 4
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> If you finish a job per day you will still have a free day. you cannot find a schedule for the given jobs.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> jobDifficulty = [1,1,1], d = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The schedule is one job per day. total difficulty will be 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= jobDifficulty.length &lt;= 300</code></li>
-	<li><code>0 &lt;= jobDifficulty[i] &lt;= 1000</code></li>
-	<li><code>1 &lt;= d &lt;= 10</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use DP. Try to cut the array into d non-empty sub-arrays. Try all possible cuts for the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use dp[i][j] where DP states are i the index of the last cut and j the number of remaining cuts. Complexity is O(n * n * d).
-</details>
diff --git a/problems/minimum-distance-between-bst-nodes/README.md b/problems/minimum-distance-between-bst-nodes/README.md
deleted file mode 100644
index 04b89d3e6..000000000
--- a/problems/minimum-distance-between-bst-nodes/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../transform-to-chessboard "Transform to Chessboard")
-　　　　　　　　　　　　　　　　
-[Next >](../letter-case-permutation "Letter Case Permutation")
-
-## [783. Minimum Distance Between BST Nodes (Easy)](https://leetcode.com/problems/minimum-distance-between-bst-nodes "二叉搜索树节点最小距离")
-
-<p>Given the <code>root</code> of a Binary Search Tree (BST), return <em>the minimum difference between the values of any two different nodes in the tree</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/05/bst1.jpg" style="width: 292px; height: 301px;" />
-<pre>
-<strong>Input:</strong> root = [4,2,6,1,3]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/05/bst2.jpg" style="width: 282px; height: 301px;" />
-<pre>
-<strong>Input:</strong> root = [1,0,48,null,null,12,49]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[2, 100]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 530: <a href="https://leetcode.com/problems/minimum-absolute-difference-in-bst/" target="_blank">https://leetcode.com/problems/minimum-absolute-difference-in-bst/</a></p>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Inorder Traversal](../binary-tree-inorder-traversal) (Easy)
diff --git a/problems/minimum-distance-between-bst-nodes/minimum_distance_between_bst_nodes.go b/problems/minimum-distance-between-bst-nodes/minimum_distance_between_bst_nodes.go
deleted file mode 100644
index 41cfd5231..000000000
--- a/problems/minimum-distance-between-bst-nodes/minimum_distance_between_bst_nodes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem783
diff --git a/problems/minimum-distance-between-bst-nodes/minimum_distance_between_bst_nodes_test.go b/problems/minimum-distance-between-bst-nodes/minimum_distance_between_bst_nodes_test.go
deleted file mode 100644
index 41cfd5231..000000000
--- a/problems/minimum-distance-between-bst-nodes/minimum_distance_between_bst_nodes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem783
diff --git a/problems/minimum-distance-to-the-target-element/README.md b/problems/minimum-distance-to-the-target-element/README.md
deleted file mode 100644
index 12fce50f8..000000000
--- a/problems/minimum-distance-to-the-target-element/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../closest-room "Closest Room")
-　　　　　　　　　　　　　　　　
-[Next >](../splitting-a-string-into-descending-consecutive-values "Splitting a String Into Descending Consecutive Values")
-
-## [1848. Minimum Distance to the Target Element (Easy)](https://leetcode.com/problems/minimum-distance-to-the-target-element "到目标元素的最小距离")
-
-<p>Given an integer array <code>nums</code> <strong>(0-indexed)</strong> and two integers <code>target</code> and <code>start</code>, find an index <code>i</code> such that <code>nums[i] == target</code> and <code>abs(i - start)</code> is <strong>minimized</strong>. Note that&nbsp;<code>abs(x)</code>&nbsp;is the absolute value of <code>x</code>.</p>
-
-<p>Return <code>abs(i - start)</code>.</p>
-
-<p>It is <strong>guaranteed</strong> that <code>target</code> exists in <code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5], target = 5, start = 3
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> nums[4] = 5 is the only value equal to target, so the answer is abs(4 - 3) = 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1], target = 1, start = 0
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> nums[0] = 1 is the only value equal to target, so the answer is abs(0 - 0) = 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,1,1,1,1,1,1,1], target = 1, start = 0
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Every value of nums is 1, but nums[0] minimizes abs(i - start), which is abs(0 - 0) = 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= start &lt; nums.length</code></li>
-	<li><code>target</code> is in <code>nums</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Loop in both directions until you find the target element.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each index i such that nums[i] == target calculate abs(i - start).
-</details>
diff --git a/problems/minimum-distance-to-type-a-word-using-two-fingers/README.md b/problems/minimum-distance-to-type-a-word-using-two-fingers/README.md
deleted file mode 100644
index 48841f1ad..000000000
--- a/problems/minimum-distance-to-type-a-word-using-two-fingers/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-operations-to-make-network-connected "Number of Operations to Make Network Connected")
-　　　　　　　　　　　　　　　　
-[Next >](../restaurant-growth "Restaurant Growth")
-
-## [1320. Minimum Distance to Type a Word Using Two Fingers (Hard)](https://leetcode.com/problems/minimum-distance-to-type-a-word-using-two-fingers "二指输入的的最小距离")
-
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/02/leetcode_keyboard.png" style="width: 349px; height: 209px;" />
-<p>You have a keyboard layout as shown above in the <strong>X-Y</strong> plane, where each English uppercase letter is located at some coordinate.</p>
-
-<ul>
-	<li>For example, the letter <code>&#39;A&#39;</code> is located at coordinate <code>(0, 0)</code>, the letter <code>&#39;B&#39;</code> is located at coordinate <code>(0, 1)</code>, the letter <code>&#39;P&#39;</code> is located at coordinate <code>(2, 3)</code> and the letter <code>&#39;Z&#39;</code> is located at coordinate <code>(4, 1)</code>.</li>
-</ul>
-
-<p>Given the string <code>word</code>, return <em>the minimum total <strong>distance</strong> to type such string using only two fingers</em>.</p>
-
-<p>The <strong>distance</strong> between coordinates <code>(x<sub>1</sub>, y<sub>1</sub>)</code> and <code>(x<sub>2</sub>, y<sub>2</sub>)</code> is <code>|x<sub>1</sub> - x<sub>2</sub>| + |y<sub>1</sub> - y<sub>2</sub>|</code>.</p>
-
-<p><strong>Note</strong> that the initial positions of your two fingers are considered free so do not count towards your total distance, also your two fingers do not have to start at the first letter or the first two letters.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;CAKE&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Using two fingers, one optimal way to type &quot;CAKE&quot; is: 
-Finger 1 on letter &#39;C&#39; -&gt; cost = 0 
-Finger 1 on letter &#39;A&#39; -&gt; cost = Distance from letter &#39;C&#39; to letter &#39;A&#39; = 2 
-Finger 2 on letter &#39;K&#39; -&gt; cost = 0 
-Finger 2 on letter &#39;E&#39; -&gt; cost = Distance from letter &#39;K&#39; to letter &#39;E&#39; = 1 
-Total distance = 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;HAPPY&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Using two fingers, one optimal way to type &quot;HAPPY&quot; is:
-Finger 1 on letter &#39;H&#39; -&gt; cost = 0
-Finger 1 on letter &#39;A&#39; -&gt; cost = Distance from letter &#39;H&#39; to letter &#39;A&#39; = 2
-Finger 2 on letter &#39;P&#39; -&gt; cost = 0
-Finger 2 on letter &#39;P&#39; -&gt; cost = Distance from letter &#39;P&#39; to letter &#39;P&#39; = 0
-Finger 1 on letter &#39;Y&#39; -&gt; cost = Distance from letter &#39;A&#39; to letter &#39;Y&#39; = 4
-Total distance = 6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= word.length &lt;= 300</code></li>
-	<li><code>word</code> consists of uppercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Minimum Time to Type Word Using Special Typewriter](../minimum-time-to-type-word-using-special-typewriter) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-dp[i][j][k]: smallest movements when you have one finger on i-th char and the other one on j-th char already having written k first characters from word.
-</details>
diff --git a/problems/minimum-domino-rotations-for-equal-row/README.md b/problems/minimum-domino-rotations-for-equal-row/README.md
deleted file mode 100644
index 70e13dd34..000000000
--- a/problems/minimum-domino-rotations-for-equal-row/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../clumsy-factorial "Clumsy Factorial")
-　　　　　　　　　　　　　　　　
-[Next >](../construct-binary-search-tree-from-preorder-traversal "Construct Binary Search Tree from Preorder Traversal")
-
-## [1007. Minimum Domino Rotations For Equal Row (Medium)](https://leetcode.com/problems/minimum-domino-rotations-for-equal-row "行相等的最少多米诺旋转")
-
-<p>In a row of dominoes, <code>tops[i]</code> and <code>bottoms[i]</code> represent the top and bottom halves of the <code>i<sup>th</sup></code> domino. (A domino is a tile with two numbers from 1 to 6 - one on each half of the tile.)</p>
-
-<p>We may rotate the <code>i<sup>th</sup></code> domino, so that <code>tops[i]</code> and <code>bottoms[i]</code> swap values.</p>
-
-<p>Return the minimum number of rotations so that all the values in <code>tops</code> are the same, or all the values in <code>bottoms</code> are the same.</p>
-
-<p>If it cannot be done, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/14/domino.png" style="height: 300px; width: 421px;" />
-<pre>
-<strong>Input:</strong> tops = [2,1,2,4,2,2], bottoms = [5,2,6,2,3,2]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-The first figure represents the dominoes as given by tops and bottoms: before we do any rotations.
-If we rotate the second and fourth dominoes, we can make every value in the top row equal to 2, as indicated by the second figure.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tops = [3,5,1,2,3], bottoms = [3,6,3,3,4]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> 
-In this case, it is not possible to rotate the dominoes to make one row of values equal.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= tops.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>bottoms.length == tops.length</code></li>
-	<li><code>1 &lt;= tops[i], bottoms[i] &lt;= 6</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
diff --git a/problems/minimum-domino-rotations-for-equal-row/minimum_domino_rotations_for_equal_row.go b/problems/minimum-domino-rotations-for-equal-row/minimum_domino_rotations_for_equal_row.go
deleted file mode 100644
index 08028e9f9..000000000
--- a/problems/minimum-domino-rotations-for-equal-row/minimum_domino_rotations_for_equal_row.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package problem1007
-
-func minDominoRotations(A []int, B []int) int {
-	if res, ok := check(A, B, A[0]); ok {
-		return res
-	}
-	if res, ok := check(A, B, B[0]); ok {
-		return res
-	}
-	return -1
-}
-
-func check(A, B []int, flag int) (int, bool) {
-	a, b := 0, 0
-	i, n := 0, len(A)
-	for ; i < n && (A[i] == flag || B[i] == flag); i++ {
-		if A[i] != flag { // A needs a swap to be all flag
-			a++
-		}
-		if B[i] != flag { // B needs a swap to be all flag
-			b++
-		}
-	}
-	return min(a, b), i == n
-}
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
diff --git a/problems/minimum-elements-to-add-to-form-a-given-sum/README.md b/problems/minimum-elements-to-add-to-form-a-given-sum/README.md
deleted file mode 100644
index 1bad5bcd5..000000000
--- a/problems/minimum-elements-to-add-to-form-a-given-sum/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-binary-string-has-at-most-one-segment-of-ones "Check if Binary String Has at Most One Segment of Ones")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-restricted-paths-from-first-to-last-node "Number of Restricted Paths From First to Last Node")
-
-## [1785. Minimum Elements to Add to Form a Given Sum (Medium)](https://leetcode.com/problems/minimum-elements-to-add-to-form-a-given-sum "构成特定和需要添加的最少元素")
-
-<p>You are given an integer array <code>nums</code> and two integers <code>limit</code> and <code>goal</code>. The array <code>nums</code> has an interesting property that <code>abs(nums[i]) &lt;= limit</code>.</p>
-
-<p>Return <em>the minimum number of elements you need to add to make the sum of the array equal to </em><code>goal</code>. The array must maintain its property that <code>abs(nums[i]) &lt;= limit</code>.</p>
-
-<p>Note that <code>abs(x)</code> equals <code>x</code> if <code>x &gt;= 0</code>, and <code>-x</code> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,-1,1], limit = 3, goal = -4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You can add -2 and -3, then the sum of the array will be 1 - 1 + 1 - 2 - 3 = -4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,-10,9,1], limit = 100, goal = 0
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= limit &lt;= 10<sup>6</sup></code></li>
-	<li><code>-limit &lt;= nums[i] &lt;= limit</code></li>
-	<li><code>-10<sup>9</sup> &lt;= goal &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try thinking about the problem as if the array is empty. Then you only need to form goal using elements whose absolute value is <= limit.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can greedily set all of the elements except one to limit or -limit, so the number of elements you need is ceil(abs(goal)/ limit).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can "normalize" goal by offsetting it by the sum of the array. For example, if the goal is 5 and the sum is -3, then it's exactly the same as if the goal is 8 and the array is empty.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The answer is ceil(abs(goal-sum)/limit) = (abs(goal-sum)+limit-1) / limit.
-</details>
diff --git a/problems/minimum-factorization/README.md b/problems/minimum-factorization/README.md
deleted file mode 100644
index 2de984add..000000000
--- a/problems/minimum-factorization/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-distance-in-arrays "Maximum Distance in Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../exchange-seats "Exchange Seats")
-
-## [625. Minimum Factorization (Medium)](https://leetcode.com/problems/minimum-factorization "最小因式分解")
-
-<p>Given a positive integer <code>a</code>, find the smallest positive integer <code>b</code> whose multiplication of each digit equals to <code>a</code>. </p>
-
-<p>
-If there is no answer or the answer is not fit in 32-bit signed integer, then return 0.</p>
-
-<p>
-<b>Example 1</b><br>
-Input:
-<pre>48 </pre>
-Output:
-<pre>68</pre>
-</p>
-
-<p>
-<b>Example 2</b><br>
-Input: 
-<pre>15</pre>
-
-Output:
-<pre>35</pre>
-</p>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
diff --git a/problems/minimum-factorization/minimum_factorization.go b/problems/minimum-factorization/minimum_factorization.go
deleted file mode 100644
index 87dc269fd..000000000
--- a/problems/minimum-factorization/minimum_factorization.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem625
diff --git a/problems/minimum-factorization/minimum_factorization_test.go b/problems/minimum-factorization/minimum_factorization_test.go
deleted file mode 100644
index 87dc269fd..000000000
--- a/problems/minimum-factorization/minimum_factorization_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem625
diff --git a/problems/minimum-falling-path-sum-ii/README.md b/problems/minimum-falling-path-sum-ii/README.md
deleted file mode 100644
index 446fbe15c..000000000
--- a/problems/minimum-falling-path-sum-ii/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-covered-intervals "Remove Covered Intervals")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-binary-number-in-a-linked-list-to-integer "Convert Binary Number in a Linked List to Integer")
-
-## [1289. Minimum Falling Path Sum II (Hard)](https://leetcode.com/problems/minimum-falling-path-sum-ii "下降路径最小和  II")
-
-<p>Given an <code>n x n</code> integer matrix <code>grid</code>, return <em>the minimum sum of a <strong>falling path with non-zero shifts</strong></em>.</p>
-
-<p>A <strong>falling path with non-zero shifts</strong> is a choice of exactly one element from each row of <code>grid</code> such that no two elements chosen in adjacent rows are in the same column.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/10/falling-grid.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> arr = [[1,2,3],[4,5,6],[7,8,9]]
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> 
-The possible falling paths are:
-[1,5,9], [1,5,7], [1,6,7], [1,6,8],
-[2,4,8], [2,4,9], [2,6,7], [2,6,8],
-[3,4,8], [3,4,9], [3,5,7], [3,5,9]
-The falling path with the smallest sum is&nbsp;[1,5,7], so the answer is&nbsp;13.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[7]]
-<strong>Output:</strong> 7
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length == grid[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 200</code></li>
-	<li><code>-99 &lt;= grid[i][j] &lt;= 99</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Minimum Falling Path Sum](../minimum-falling-path-sum) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let dp[i][j] be the answer for the first i rows such that column j is chosen from row i.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use the concept of cumulative array to optimize the complexity of the solution.
-</details>
diff --git a/problems/minimum-falling-path-sum/README.md b/problems/minimum-falling-path-sum/README.md
deleted file mode 100644
index cbd4580c6..000000000
--- a/problems/minimum-falling-path-sum/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-subarrays-with-sum "Binary Subarrays With Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../beautiful-array "Beautiful Array")
-
-## [931. Minimum Falling Path Sum (Medium)](https://leetcode.com/problems/minimum-falling-path-sum "下降路径最小和")
-
-<p>Given an <code>n x n</code> array of integers <code>matrix</code>, return <em>the <strong>minimum sum</strong> of any <strong>falling path</strong> through</em> <code>matrix</code>.</p>
-
-<p>A <strong>falling path</strong> starts at any element in the first row and chooses the element in the next row that is either directly below or diagonally left/right. Specifically, the next element from position <code>(row, col)</code> will be <code>(row + 1, col - 1)</code>, <code>(row + 1, col)</code>, or <code>(row + 1, col + 1)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/03/failing1-grid.jpg" style="width: 499px; height: 500px;" />
-<pre>
-<strong>Input:</strong> matrix = [[2,1,3],[6,5,4],[7,8,9]]
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> There are two falling paths with a minimum sum as shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/03/failing2-grid.jpg" style="width: 164px; height: 365px;" />
-<pre>
-<strong>Input:</strong> matrix = [[-19,57],[-40,-5]]
-<strong>Output:</strong> -59
-<strong>Explanation:</strong> The falling path with a minimum sum is shown.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == matrix.length == matrix[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>-100 &lt;= matrix[i][j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Minimum Falling Path Sum II](../minimum-falling-path-sum-ii) (Hard)
diff --git a/problems/minimum-falling-path-sum/minimum_falling_path_sum.go b/problems/minimum-falling-path-sum/minimum_falling_path_sum.go
deleted file mode 100644
index bd5dcdca7..000000000
--- a/problems/minimum-falling-path-sum/minimum_falling_path_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem931
diff --git a/problems/minimum-falling-path-sum/minimum_falling_path_sum_test.go b/problems/minimum-falling-path-sum/minimum_falling_path_sum_test.go
deleted file mode 100644
index bd5dcdca7..000000000
--- a/problems/minimum-falling-path-sum/minimum_falling_path_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem931
diff --git a/problems/minimum-flips-to-make-a-or-b-equal-to-c/README.md b/problems/minimum-flips-to-make-a-or-b-equal-to-c/README.md
deleted file mode 100644
index 81c358c5a..000000000
--- a/problems/minimum-flips-to-make-a-or-b-equal-to-c/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-integer-to-the-sum-of-two-no-zero-integers "Convert Integer to the Sum of Two No-Zero Integers")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-operations-to-make-network-connected "Number of Operations to Make Network Connected")
-
-## [1318. Minimum Flips to Make a OR b Equal to c (Medium)](https://leetcode.com/problems/minimum-flips-to-make-a-or-b-equal-to-c "或运算的最小翻转次数")
-
-<p>Given 3 positives numbers <code>a</code>, <code>b</code> and <code>c</code>. Return the minimum flips required in some bits of <code>a</code> and <code>b</code> to make (&nbsp;<code>a</code> OR <code>b</code> == <code>c</code>&nbsp;). (bitwise OR operation).<br />
-Flip operation&nbsp;consists of change&nbsp;<strong>any</strong>&nbsp;single bit 1 to 0 or change the bit 0 to 1&nbsp;in their binary representation.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/01/06/sample_3_1676.png" style="width: 260px; height: 87px;" /></p>
-
-<pre>
-<strong>Input:</strong> a = 2, b = 6, c = 5
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>After flips a = 1 , b = 4 , c = 5 such that (<code>a</code> OR <code>b</code> == <code>c</code>)</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 4, b = 2, c = 7
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 1, b = 2, c = 3
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= a &lt;= 10^9</code></li>
-	<li><code>1 &lt;= b&nbsp;&lt;= 10^9</code></li>
-	<li><code>1 &lt;= c&nbsp;&lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check the bits one by one whether they need to be flipped.
-</details>
diff --git a/problems/minimum-garden-perimeter-to-collect-enough-apples/README.md b/problems/minimum-garden-perimeter-to-collect-enough-apples/README.md
deleted file mode 100644
index 8b7b380b8..000000000
--- a/problems/minimum-garden-perimeter-to-collect-enough-apples/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-weeks-for-which-you-can-work "Maximum Number of Weeks for Which You Can Work")
-　　　　　　　　　　　　　　　　
-[Next >](../count-number-of-special-subsequences "Count Number of Special Subsequences")
-
-## [1954. Minimum Garden Perimeter to Collect Enough Apples (Medium)](https://leetcode.com/problems/minimum-garden-perimeter-to-collect-enough-apples "收集足够苹果的最小花园周长")
-
-<p>In a garden represented as an infinite 2D grid, there is an apple tree planted at <strong>every</strong> integer coordinate. The apple tree planted at an integer coordinate <code>(i, j)</code> has <code>|i| + |j|</code> apples growing on it.</p>
-
-<p>You will buy an axis-aligned <strong>square plot</strong> of land that is centered at <code>(0, 0)</code>.</p>
-
-<p>Given an integer <code>neededApples</code>, return <em>the <strong>minimum perimeter</strong> of a plot such that <strong>at least</strong></em><strong> </strong><code>neededApples</code> <em>apples are <strong>inside or on</strong> the perimeter of that plot</em>.</p>
-
-<p>The value of <code>|x|</code> is defined as:</p>
-
-<ul>
-	<li><code>x</code> if <code>x &gt;= 0</code></li>
-	<li><code>-x</code> if <code>x &lt; 0</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/08/30/1527_example_1_2.png" style="width: 442px; height: 449px;" />
-<pre>
-<strong>Input:</strong> neededApples = 1
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> A square plot of side length 1 does not contain any apples.
-However, a square plot of side length 2 has 12 apples inside (as depicted in the image above).
-The perimeter is 2 * 4 = 8.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> neededApples = 13
-<strong>Output:</strong> 16
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> neededApples = 1000000000
-<strong>Output:</strong> 5040
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= neededApples &lt;= 10<sup>15</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find a formula for the number of apples inside a square with a side length L.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Iterate over the possible lengths of the square until enough apples are collected.
-</details>
diff --git a/problems/minimum-genetic-mutation/README.md b/problems/minimum-genetic-mutation/README.md
deleted file mode 100644
index 464225609..000000000
--- a/problems/minimum-genetic-mutation/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-oone-data-structure "All O`one Data Structure")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-segments-in-a-string "Number of Segments in a String")
-
-## [433. Minimum Genetic Mutation (Medium)](https://leetcode.com/problems/minimum-genetic-mutation "最小基因变化")
-
-<p>A gene string can be represented by an 8-character long string, with choices from <code>&#39;A&#39;</code>, <code>&#39;C&#39;</code>, <code>&#39;G&#39;</code>, and <code>&#39;T&#39;</code>.</p>
-
-<p>Suppose we need to investigate a mutation from a gene string <code>start</code> to a gene string <code>end</code> where one mutation is defined as one single character changed in the gene string.</p>
-
-<ul>
-	<li>For example, <code>&quot;AACCGGTT&quot; --&gt; &quot;AACCGGTA&quot;</code> is one mutation.</li>
-</ul>
-
-<p>There is also a gene bank <code>bank</code> that records all the valid gene mutations. A gene must be in <code>bank</code> to make it a valid gene string.</p>
-
-<p>Given the two gene strings <code>start</code> and <code>end</code> and the gene bank <code>bank</code>, return <em>the minimum number of mutations needed to mutate from </em><code>start</code><em> to </em><code>end</code>. If there is no such a mutation, return <code>-1</code>.</p>
-
-<p>Note that the starting point is assumed to be valid, so it might not be included in the bank.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> start = &quot;AACCGGTT&quot;, end = &quot;AACCGGTA&quot;, bank = [&quot;AACCGGTA&quot;]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> start = &quot;AACCGGTT&quot;, end = &quot;AAACGGTA&quot;, bank = [&quot;AACCGGTA&quot;,&quot;AACCGCTA&quot;,&quot;AAACGGTA&quot;]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> start = &quot;AAAAACCC&quot;, end = &quot;AACCCCCC&quot;, bank = [&quot;AAAACCCC&quot;,&quot;AAACCCCC&quot;,&quot;AACCCCCC&quot;]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>start.length == 8</code></li>
-	<li><code>end.length == 8</code></li>
-	<li><code>0 &lt;= bank.length &lt;= 10</code></li>
-	<li><code>bank[i].length == 8</code></li>
-	<li><code>start</code>, <code>end</code>, and <code>bank[i]</code> consist of only the characters <code>[&#39;A&#39;, &#39;C&#39;, &#39;G&#39;, &#39;T&#39;]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Word Ladder](../word-ladder) (Hard)
diff --git a/problems/minimum-genetic-mutation/minimum_genetic_mutation.go b/problems/minimum-genetic-mutation/minimum_genetic_mutation.go
deleted file mode 100644
index ff16adf6c..000000000
--- a/problems/minimum-genetic-mutation/minimum_genetic_mutation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem433
diff --git a/problems/minimum-genetic-mutation/minimum_genetic_mutation_test.go b/problems/minimum-genetic-mutation/minimum_genetic_mutation_test.go
deleted file mode 100644
index ff16adf6c..000000000
--- a/problems/minimum-genetic-mutation/minimum_genetic_mutation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem433
diff --git a/problems/minimum-height-trees/README.md b/problems/minimum-height-trees/README.md
deleted file mode 100644
index 5f5d66e2d..000000000
--- a/problems/minimum-height-trees/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-time-to-buy-and-sell-stock-with-cooldown "Best Time to Buy and Sell Stock with Cooldown")
-　　　　　　　　　　　　　　　　
-[Next >](../sparse-matrix-multiplication "Sparse Matrix Multiplication")
-
-## [310. Minimum Height Trees (Medium)](https://leetcode.com/problems/minimum-height-trees "最小高度树")
-
-<p>A tree is an undirected graph in which any two vertices are connected by&nbsp;<i>exactly</i>&nbsp;one path. In other words, any connected graph without simple cycles is a tree.</p>
-
-<p>Given a tree of <code>n</code> nodes&nbsp;labelled from <code>0</code> to <code>n - 1</code>, and an array of&nbsp;<code>n - 1</code>&nbsp;<code>edges</code> where <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that there is an undirected edge between the two nodes&nbsp;<code>a<sub>i</sub></code> and&nbsp;<code>b<sub>i</sub></code> in the tree,&nbsp;you can choose any node of the tree as the root. When you select a node <code>x</code> as the root, the result tree has height <code>h</code>. Among all possible rooted trees, those with minimum height (i.e. <code>min(h)</code>)&nbsp; are called <strong>minimum height trees</strong> (MHTs).</p>
-
-<p>Return <em>a list of all <strong>MHTs&#39;</strong> root labels</em>.&nbsp;You can return the answer in <strong>any order</strong>.</p>
-
-<p>The <strong>height</strong> of a rooted tree is the number of edges on the longest downward path between the root and a leaf.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/01/e1.jpg" style="width: 800px; height: 213px;" />
-<pre>
-<strong>Input:</strong> n = 4, edges = [[1,0],[1,2],[1,3]]
-<strong>Output:</strong> [1]
-<strong>Explanation:</strong> As shown, the height of the tree is 1 when the root is the node with label 1 which is the only MHT.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/01/e2.jpg" style="width: 800px; height: 321px;" />
-<pre>
-<strong>Input:</strong> n = 6, edges = [[3,0],[3,1],[3,2],[3,4],[5,4]]
-<strong>Output:</strong> [3,4]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, edges = []
-<strong>Output:</strong> [0]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, edges = [[0,1]]
-<strong>Output:</strong> [0,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>edges.length == n - 1</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt; n</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-	<li>All the pairs <code>(a<sub>i</sub>, b<sub>i</sub>)</code> are distinct.</li>
-	<li>The given input is <strong>guaranteed</strong> to be a tree and there will be <strong>no repeated</strong> edges.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-
-### Similar Questions
-  1. [Course Schedule](../course-schedule) (Medium)
-  1. [Course Schedule II](../course-schedule-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many MHTs can a graph have at most?
-</details>
diff --git a/problems/minimum-height-trees/minimum_height_trees.go b/problems/minimum-height-trees/minimum_height_trees.go
deleted file mode 100644
index b0d636f78..000000000
--- a/problems/minimum-height-trees/minimum_height_trees.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem310
diff --git a/problems/minimum-height-trees/minimum_height_trees_test.go b/problems/minimum-height-trees/minimum_height_trees_test.go
deleted file mode 100644
index b0d636f78..000000000
--- a/problems/minimum-height-trees/minimum_height_trees_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem310
diff --git a/problems/minimum-incompatibility/README.md b/problems/minimum-incompatibility/README.md
deleted file mode 100644
index 8cce8ee4d..000000000
--- a/problems/minimum-incompatibility/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../concatenation-of-consecutive-binary-numbers "Concatenation of Consecutive Binary Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-palindromic-subsequence-ii "Longest Palindromic Subsequence II")
-
-## [1681. Minimum Incompatibility (Hard)](https://leetcode.com/problems/minimum-incompatibility "最小不兼容性")
-
-<p>You are given an integer array <code>nums</code>​​​ and an integer <code>k</code>. You are asked to distribute this array into <code>k</code> subsets of <strong>equal size</strong> such that there are no two equal elements in the same subset.</p>
-
-<p>A subset&#39;s <strong>incompatibility</strong> is the difference between the maximum and minimum elements in that array.</p>
-
-<p>Return <em>the <strong>minimum possible sum of incompatibilities</strong> of the </em><code>k</code> <em>subsets after distributing the array optimally, or return </em><code>-1</code><em> if it is not possible.</em></p>
-
-<p>A subset is a group integers that appear in the array with no particular order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1,4], k = 2
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The optimal distribution of subsets is [1,2] and [1,4].
-The incompatibility is (2-1) + (4-1) = 4.
-Note that [1,1] and [2,4] would result in a smaller sum, but the first subset contains 2 equal elements.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [6,3,8,1,3,1,2,2], k = 4
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The optimal distribution of subsets is [1,2], [2,3], [6,8], and [1,3].
-The incompatibility is (2-1) + (3-2) + (8-6) + (3-1) = 6.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,3,3,6,3,3], k = 3
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> It is impossible to distribute nums into 3 subsets where no two elements are equal in the same subset.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= nums.length &lt;= 16</code></li>
-	<li><code>nums.length</code> is divisible by <code>k</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The constraints are small enough for a backtrack solution but not any backtrack solution
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If we use a naive n^k don't you think it can be optimized
-</details>
diff --git a/problems/minimum-increment-to-make-array-unique/README.md b/problems/minimum-increment-to-make-array-unique/README.md
deleted file mode 100644
index 27f098950..000000000
--- a/problems/minimum-increment-to-make-array-unique/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-columns-to-make-sorted "Delete Columns to Make Sorted")
-　　　　　　　　　　　　　　　　
-[Next >](../validate-stack-sequences "Validate Stack Sequences")
-
-## [945. Minimum Increment to Make Array Unique (Medium)](https://leetcode.com/problems/minimum-increment-to-make-array-unique "使数组唯一的最小增量")
-
-<p>You are given an integer array <code>nums</code>. In one move, you can pick an index <code>i</code> where <code>0 &lt;= i &lt; nums.length</code> and increment <code>nums[i]</code> by <code>1</code>.</p>
-
-<p>Return <em>the minimum number of moves to make every value in </em><code>nums</code><em> <strong>unique</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,2]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> After 1 move, the array could be [1, 2, 3].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,1,2,1,7]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> After 6 moves, the array could be [3, 4, 1, 2, 5, 7].
-It can be shown with 5 or less moves that it is impossible for the array to have all unique values.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/minimum-increment-to-make-array-unique/minimum_increment_to_make_array_unique.go b/problems/minimum-increment-to-make-array-unique/minimum_increment_to_make_array_unique.go
deleted file mode 100644
index 927fc71cf..000000000
--- a/problems/minimum-increment-to-make-array-unique/minimum_increment_to_make_array_unique.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem945
diff --git a/problems/minimum-increment-to-make-array-unique/minimum_increment_to_make_array_unique_test.go b/problems/minimum-increment-to-make-array-unique/minimum_increment_to_make_array_unique_test.go
deleted file mode 100644
index 927fc71cf..000000000
--- a/problems/minimum-increment-to-make-array-unique/minimum_increment_to_make_array_unique_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem945
diff --git a/problems/minimum-index-sum-of-two-lists/README.md b/problems/minimum-index-sum-of-two-lists/README.md
deleted file mode 100644
index 846a3b8fa..000000000
--- a/problems/minimum-index-sum-of-two-lists/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-addition-ii "Range Addition II")
-　　　　　　　　　　　　　　　　
-[Next >](../non-negative-integers-without-consecutive-ones "Non-negative Integers without Consecutive Ones")
-
-## [599. Minimum Index Sum of Two Lists (Easy)](https://leetcode.com/problems/minimum-index-sum-of-two-lists "两个列表的最小索引总和")
-
-<p>Suppose Andy and Doris want to choose a restaurant for dinner, and they both have a list of favorite restaurants represented by strings.</p>
-
-<p>You need to help them find out their <b>common interest</b> with the <b>least list index sum</b>. If there is a choice tie between answers, output all of them with no order requirement. You could assume there always exists an answer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> list1 = [&quot;Shogun&quot;,&quot;Tapioca Express&quot;,&quot;Burger King&quot;,&quot;KFC&quot;], list2 = [&quot;Piatti&quot;,&quot;The Grill at Torrey Pines&quot;,&quot;Hungry Hunter Steakhouse&quot;,&quot;Shogun&quot;]
-<strong>Output:</strong> [&quot;Shogun&quot;]
-<strong>Explanation:</strong> The only restaurant they both like is &quot;Shogun&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> list1 = [&quot;Shogun&quot;,&quot;Tapioca Express&quot;,&quot;Burger King&quot;,&quot;KFC&quot;], list2 = [&quot;KFC&quot;,&quot;Shogun&quot;,&quot;Burger King&quot;]
-<strong>Output:</strong> [&quot;Shogun&quot;]
-<strong>Explanation:</strong> The restaurant they both like and have the least index sum is &quot;Shogun&quot; with index sum 1 (0+1).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> list1 = [&quot;Shogun&quot;,&quot;Tapioca Express&quot;,&quot;Burger King&quot;,&quot;KFC&quot;], list2 = [&quot;KFC&quot;,&quot;Burger King&quot;,&quot;Tapioca Express&quot;,&quot;Shogun&quot;]
-<strong>Output:</strong> [&quot;KFC&quot;,&quot;Burger King&quot;,&quot;Tapioca Express&quot;,&quot;Shogun&quot;]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> list1 = [&quot;Shogun&quot;,&quot;Tapioca Express&quot;,&quot;Burger King&quot;,&quot;KFC&quot;], list2 = [&quot;KNN&quot;,&quot;KFC&quot;,&quot;Burger King&quot;,&quot;Tapioca Express&quot;,&quot;Shogun&quot;]
-<strong>Output:</strong> [&quot;KFC&quot;,&quot;Burger King&quot;,&quot;Tapioca Express&quot;,&quot;Shogun&quot;]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> list1 = [&quot;KFC&quot;], list2 = [&quot;KFC&quot;]
-<strong>Output:</strong> [&quot;KFC&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= list1.length, list2.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= list1[i].length, list2[i].length &lt;= 30</code></li>
-	<li><code>list1[i]</code> and <code>list2[i]</code> consist of spaces <code>&#39; &#39;</code> and English letters.</li>
-	<li>All the stings of <code>list1</code> are <strong>unique</strong>.</li>
-	<li>All the stings of <code>list2</code>&nbsp;are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Intersection of Two Linked Lists](../intersection-of-two-linked-lists) (Easy)
diff --git a/problems/minimum-index-sum-of-two-lists/minimum_index_sum_of_two_lists.go b/problems/minimum-index-sum-of-two-lists/minimum_index_sum_of_two_lists.go
deleted file mode 100644
index d84e3e167..000000000
--- a/problems/minimum-index-sum-of-two-lists/minimum_index_sum_of_two_lists.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem599
diff --git a/problems/minimum-index-sum-of-two-lists/minimum_index_sum_of_two_lists_test.go b/problems/minimum-index-sum-of-two-lists/minimum_index_sum_of_two_lists_test.go
deleted file mode 100644
index d84e3e167..000000000
--- a/problems/minimum-index-sum-of-two-lists/minimum_index_sum_of_two_lists_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem599
diff --git a/problems/minimum-initial-energy-to-finish-tasks/README.md b/problems/minimum-initial-energy-to-finish-tasks/README.md
deleted file mode 100644
index c8593ac98..000000000
--- a/problems/minimum-initial-energy-to-finish-tasks/README.md
+++ /dev/null
@@ -1,90 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ways-to-make-a-fair-array "Ways to Make a Fair Array")
-　　　　　　　　　　　　　　　　
-[Next >](../change-the-root-of-a-binary-tree "Change the Root of a Binary Tree")
-
-## [1665. Minimum Initial Energy to Finish Tasks (Hard)](https://leetcode.com/problems/minimum-initial-energy-to-finish-tasks "完成所有任务的最少初始能量")
-
-<p>You are given an array <code>tasks</code> where <code>tasks[i] = [actual<sub>i</sub>, minimum<sub>i</sub>]</code>:</p>
-
-<ul>
-	<li><code>actual<sub>i</sub></code> is the actual amount of energy you <strong>spend to finish</strong> the <code>i<sup>th</sup></code> task.</li>
-	<li><code>minimum<sub>i</sub></code> is the minimum amount of energy you <strong>require to begin</strong> the <code>i<sup>th</sup></code> task.</li>
-</ul>
-
-<p>For example, if the task is <code>[10, 12]</code> and your current energy is <code>11</code>, you cannot start this task. However, if your current energy is <code>13</code>, you can complete this task, and your energy will be <code>3</code> after finishing it.</p>
-
-<p>You can finish the tasks in <strong>any order</strong> you like.</p>
-
-<p>Return <em>the <strong>minimum</strong> initial amount of energy you will need</em> <em>to finish all the tasks</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [[1,2],[2,4],[4,8]]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong>
-Starting with 8 energy, we finish the tasks in the following order:
-    - 3rd task. Now energy = 8 - 4 = 4.
-    - 2nd task. Now energy = 4 - 2 = 2.
-    - 1st task. Now energy = 2 - 1 = 1.
-Notice that even though we have leftover energy, starting with 7 energy does not work because we cannot do the 3rd task.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [[1,3],[2,4],[10,11],[10,12],[8,9]]
-<strong>Output:</strong> 32
-<strong>Explanation:</strong>
-Starting with 32 energy, we finish the tasks in the following order:
-    - 1st task. Now energy = 32 - 1 = 31.
-    - 2nd task. Now energy = 31 - 2 = 29.
-    - 3rd task. Now energy = 29 - 10 = 19.
-    - 4th task. Now energy = 19 - 10 = 9.
-    - 5th task. Now energy = 9 - 8 = 1.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [[1,7],[2,8],[3,9],[4,10],[5,11],[6,12]]
-<strong>Output:</strong> 27
-<strong>Explanation:</strong>
-Starting with 27 energy, we finish the tasks in the following order:
-    - 5th task. Now energy = 27 - 5 = 22.
-    - 2nd task. Now energy = 22 - 2 = 20.
-    - 3rd task. Now energy = 20 - 3 = 17.
-    - 1st task. Now energy = 17 - 1 = 16.
-    - 4th task. Now energy = 16 - 4 = 12.
-    - 6th task. Now energy = 12 - 6 = 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= tasks.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= actual<sub>​i</sub>&nbsp;&lt;= minimum<sub>i</sub>&nbsp;&lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can easily figure that the f(x) : does x solve this array is monotonic so binary Search is doable
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Figure a sorting pattern
-</details>
diff --git a/problems/minimum-insertion-steps-to-make-a-string-palindrome/README.md b/problems/minimum-insertion-steps-to-make-a-string-palindrome/README.md
deleted file mode 100644
index 4dea8e463..000000000
--- a/problems/minimum-insertion-steps-to-make-a-string-palindrome/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../get-watched-videos-by-your-friends "Get Watched Videos by Your Friends")
-　　　　　　　　　　　　　　　　
-[Next >](../decompress-run-length-encoded-list "Decompress Run-Length Encoded List")
-
-## [1312. Minimum Insertion Steps to Make a String Palindrome (Hard)](https://leetcode.com/problems/minimum-insertion-steps-to-make-a-string-palindrome "让字符串成为回文串的最少插入次数")
-
-<p>Given a string <code>s</code>. In one step you can insert any character at any index of the string.</p>
-
-<p>Return <em>the minimum number of steps</em> to make <code>s</code>&nbsp;palindrome.</p>
-
-<p>A&nbsp;<b>Palindrome String</b>&nbsp;is one that reads the same backward as well as forward.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;zzazz&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The string &quot;zzazz&quot; is already palindrome we don&#39;t need any insertions.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;mbadm&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> String can be &quot;mbdadbm&quot; or &quot;mdbabdm&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Inserting 5 characters the string becomes &quot;leetcodocteel&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 500</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is dynamic programming suitable for this problem ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If we know the longest palindromic sub-sequence is x and the length of the string is n then, what is the answer to this problem? It is n - x as we need n - x insertions to make the remaining characters also palindrome.
-</details>
diff --git a/problems/minimum-insertions-to-balance-a-parentheses-string/README.md b/problems/minimum-insertions-to-balance-a-parentheses-string/README.md
deleted file mode 100644
index ee880867b..000000000
--- a/problems/minimum-insertions-to-balance-a-parentheses-string/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../can-convert-string-in-k-moves "Can Convert String in K Moves")
-　　　　　　　　　　　　　　　　
-[Next >](../find-longest-awesome-substring "Find Longest Awesome Substring")
-
-## [1541. Minimum Insertions to Balance a Parentheses String (Medium)](https://leetcode.com/problems/minimum-insertions-to-balance-a-parentheses-string "平衡括号字符串的最少插入次数")
-
-<p>Given a parentheses string <code>s</code> containing only the characters <code>&#39;(&#39;</code> and <code>&#39;)&#39;</code>. A parentheses string is <strong>balanced</strong> if:</p>
-
-<ul>
-	<li>Any left parenthesis <code>&#39;(&#39;</code> must have a corresponding two consecutive right parenthesis <code>&#39;))&#39;</code>.</li>
-	<li>Left parenthesis <code>&#39;(&#39;</code> must go before the corresponding two consecutive right parenthesis <code>&#39;))&#39;</code>.</li>
-</ul>
-
-<p>In other words, we treat <code>&#39;(&#39;</code> as an opening parenthesis and <code>&#39;))&#39;</code> as a closing parenthesis.</p>
-
-<ul>
-	<li>For example, <code>&quot;())&quot;</code>, <code>&quot;())(())))&quot;</code> and <code>&quot;(())())))&quot;</code> are balanced, <code>&quot;)()&quot;</code>, <code>&quot;()))&quot;</code> and <code>&quot;(()))&quot;</code> are not balanced.</li>
-</ul>
-
-<p>You can insert the characters <code>&#39;(&#39;</code> and <code>&#39;)&#39;</code> at any position of the string to balance it if needed.</p>
-
-<p>Return <em>the minimum number of insertions</em> needed to make <code>s</code> balanced.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(()))&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The second &#39;(&#39; has two matching &#39;))&#39;, but the first &#39;(&#39; has only &#39;)&#39; matching. We need to to add one more &#39;)&#39; at the end of the string to be &quot;(())))&quot; which is balanced.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;())&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The string is already balanced.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;))())(&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Add &#39;(&#39; to match the first &#39;))&#39;, Add &#39;))&#39; to match the last &#39;(&#39;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of <code>&#39;(&#39;</code> and <code>&#39;)&#39;</code> only.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Minimum Number of Swaps to Make the String Balanced](../minimum-number-of-swaps-to-make-the-string-balanced) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a stack to keep opening brackets. If you face single closing ')' add 1 to the answer and consider it as '))'.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you have '))' with empty stack, add 1 to the answer, If after finishing you have x opening remaining in the stack, add 2x to the answer.
-</details>
diff --git a/problems/minimum-interval-to-include-each-query/README.md b/problems/minimum-interval-to-include-each-query/README.md
deleted file mode 100644
index f9a6134b5..000000000
--- a/problems/minimum-interval-to-include-each-query/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-adjacent-swaps-to-reach-the-kth-smallest-number "Minimum Adjacent Swaps to Reach the Kth Smallest Number")
-　　　　　　　　　　　　　　　　
-[Next >](../distinct-numbers-in-each-subarray "Distinct Numbers in Each Subarray")
-
-## [1851. Minimum Interval to Include Each Query (Hard)](https://leetcode.com/problems/minimum-interval-to-include-each-query "包含每个查询的最小区间")
-
-<p>You are given a 2D integer array <code>intervals</code>, where <code>intervals[i] = [left<sub>i</sub>, right<sub>i</sub>]</code> describes the <code>i<sup>th</sup></code> interval starting at <code>left<sub>i</sub></code> and ending at <code>right<sub>i</sub></code> <strong>(inclusive)</strong>. The <strong>size</strong> of an interval is defined as the number of integers it contains, or more formally <code>right<sub>i</sub> - left<sub>i</sub> + 1</code>.</p>
-
-<p>You are also given an integer array <code>queries</code>. The answer to the <code>j<sup>th</sup></code> query is the <strong>size of the smallest interval</strong> <code>i</code> such that <code>left<sub>i</sub> &lt;= queries[j] &lt;= right<sub>i</sub></code>. If no such interval exists, the answer is <code>-1</code>.</p>
-
-<p>Return <em>an array containing the answers to the queries</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,4],[2,4],[3,6],[4,4]], queries = [2,3,4,5]
-<strong>Output:</strong> [3,3,1,4]
-<strong>Explanation:</strong> The queries are processed as follows:
-- Query = 2: The interval [2,4] is the smallest interval containing 2. The answer is 4 - 2 + 1 = 3.
-- Query = 3: The interval [2,4] is the smallest interval containing 3. The answer is 4 - 2 + 1 = 3.
-- Query = 4: The interval [4,4] is the smallest interval containing 4. The answer is 4 - 4 + 1 = 1.
-- Query = 5: The interval [3,6] is the smallest interval containing 5. The answer is 6 - 3 + 1 = 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[2,3],[2,5],[1,8],[20,25]], queries = [2,19,5,22]
-<strong>Output:</strong> [2,-1,4,6]
-<strong>Explanation:</strong> The queries are processed as follows:
-- Query = 2: The interval [2,3] is the smallest interval containing 2. The answer is 3 - 2 + 1 = 2.
-- Query = 19: None of the intervals contain 19. The answer is -1.
-- Query = 5: The interval [2,5] is the smallest interval containing 5. The answer is 5 - 2 + 1 = 4.
-- Query = 22: The interval [20,25] is the smallest interval containing 22. The answer is 25 - 20 + 1 = 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= intervals.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= queries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>intervals[i].length == 2</code></li>
-	<li><code>1 &lt;= left<sub>i</sub> &lt;= right<sub>i</sub> &lt;= 10<sup>7</sup></code></li>
-	<li><code>1 &lt;= queries[j] &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Line Sweep](../../tag/line-sweep/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is there a way to order the intervals and queries such that it takes less time to query?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is there a way to add and remove intervals by going from the smallest query to the largest query to find the minimum size?
-</details>
diff --git a/problems/minimum-jumps-to-reach-home/README.md b/problems/minimum-jumps-to-reach-home/README.md
deleted file mode 100644
index 5f74939af..000000000
--- a/problems/minimum-jumps-to-reach-home/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-deletions-to-make-string-balanced "Minimum Deletions to Make String Balanced")
-　　　　　　　　　　　　　　　　
-[Next >](../distribute-repeating-integers "Distribute Repeating Integers")
-
-## [1654. Minimum Jumps to Reach Home (Medium)](https://leetcode.com/problems/minimum-jumps-to-reach-home "到家的最少跳跃次数")
-
-<p>A certain bug&#39;s home is on the x-axis at position <code>x</code>. Help them get there from position <code>0</code>.</p>
-
-<p>The bug jumps according to the following rules:</p>
-
-<ul>
-	<li>It can jump exactly <code>a</code> positions <strong>forward</strong> (to the right).</li>
-	<li>It can jump exactly <code>b</code> positions <strong>backward</strong> (to the left).</li>
-	<li>It cannot jump backward twice in a row.</li>
-	<li>It cannot jump to any <code>forbidden</code> positions.</li>
-</ul>
-
-<p>The bug may jump forward <strong>beyond</strong> its home, but it <strong>cannot jump</strong> to positions numbered with <strong>negative</strong> integers.</p>
-
-<p>Given an array of integers <code>forbidden</code>, where <code>forbidden[i]</code> means that the bug cannot jump to the position <code>forbidden[i]</code>, and integers <code>a</code>, <code>b</code>, and <code>x</code>, return <em>the minimum number of jumps needed for the bug to reach its home</em>. If there is no possible sequence of jumps that lands the bug on position <code>x</code>, return <code>-1.</code></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> forbidden = [14,4,18,1,15], a = 3, b = 15, x = 9
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 3 jumps forward (0 -&gt; 3 -&gt; 6 -&gt; 9) will get the bug home.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> forbidden = [8,3,16,6,12,20], a = 15, b = 13, x = 11
-<strong>Output:</strong> -1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> forbidden = [1,6,2,14,5,17,4], a = 16, b = 9, x = 7
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> One jump forward (0 -&gt; 16) then one jump backward (16 -&gt; 7) will get the bug home.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= forbidden.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= a, b, forbidden[i] &lt;= 2000</code></li>
-	<li><code>0 &lt;= x &lt;= 2000</code></li>
-	<li>All the elements in <code>forbidden</code> are distinct.</li>
-	<li>Position <code>x</code> is not forbidden.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think of the line as a graph
-</details>
-
-<details>
-<summary>Hint 2</summary>
-to handle the no double back jumps condition you can handle it by holding the state of your previous jump
-</details>
diff --git a/problems/minimum-knight-moves/README.md b/problems/minimum-knight-moves/README.md
deleted file mode 100644
index 6b6aae821..000000000
--- a/problems/minimum-knight-moves/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../how-many-apples-can-you-put-into-the-basket "How Many Apples Can You Put into the Basket")
-　　　　　　　　　　　　　　　　
-[Next >](../find-smallest-common-element-in-all-rows "Find Smallest Common Element in All Rows")
-
-## [1197. Minimum Knight Moves (Medium)](https://leetcode.com/problems/minimum-knight-moves "进击的骑士")
-
-<p>In an <strong>infinite</strong> chess board with coordinates from <code>-infinity</code>&nbsp;to <code>+infinity</code>, you have a <strong>knight</strong> at square&nbsp;<code>[0, 0]</code>.</p>
-
-<p>A&nbsp;knight has 8 possible moves it can make, as illustrated below. Each move is two squares in a cardinal direction, then one square in an orthogonal direction.</p>
-
-<p><img src="https://assets.leetcode.com/uploads/2018/10/12/knight.png" style="height: 200px; width: 200px;" /></p>
-
-<p>Return the&nbsp;minimum number of steps needed to move the knight to the square <code>[x, y]</code>.&nbsp; It is guaranteed the answer exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 2, y = 1
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>[0, 0] &rarr; [2, 1]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 5, y = 5
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>[0, 0] &rarr; [2, 1] &rarr; [4, 2] &rarr; [3, 4] &rarr; [5, 5]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>|x| + |y| &lt;= 300</code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can simulate the movements since the limits are low.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is there a search algorithm applicable to this problem?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Since we want the minimum number of moves, we can use Breadth First Search.
-</details>
diff --git a/problems/minimum-length-of-string-after-deleting-similar-ends/README.md b/problems/minimum-length-of-string-after-deleting-similar-ends/README.md
deleted file mode 100644
index 83de2d6e8..000000000
--- a/problems/minimum-length-of-string-after-deleting-similar-ends/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-absolute-sum-of-any-subarray "Maximum Absolute Sum of Any Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-events-that-can-be-attended-ii "Maximum Number of Events That Can Be Attended II")
-
-## [1750. Minimum Length of String After Deleting Similar Ends (Medium)](https://leetcode.com/problems/minimum-length-of-string-after-deleting-similar-ends "删除字符串两端相同字符后的最短长度")
-
-<p>Given a string <code>s</code> consisting only of characters <code>&#39;a&#39;</code>, <code>&#39;b&#39;</code>, and <code>&#39;c&#39;</code>. You are asked to apply the following algorithm on the string any number of times:</p>
-
-<ol>
-	<li>Pick a <strong>non-empty</strong> prefix from the string <code>s</code> where all the characters in the prefix are equal.</li>
-	<li>Pick a <strong>non-empty</strong> suffix from the string <code>s</code> where all the characters in this suffix are equal.</li>
-	<li>The prefix and the suffix should not intersect at any index.</li>
-	<li>The characters from the prefix and suffix must be the same.</li>
-	<li>Delete both the prefix and the suffix.</li>
-</ol>
-
-<p>Return <em>the <strong>minimum length</strong> of </em><code>s</code> <em>after performing the above operation any number of times (possibly zero times)</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ca&quot;
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>You can&#39;t remove any characters, so the string stays as is.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cabaabac&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> An optimal sequence of operations is:
-- Take prefix = &quot;c&quot; and suffix = &quot;c&quot; and remove them, s = &quot;abaaba&quot;.
-- Take prefix = &quot;a&quot; and suffix = &quot;a&quot; and remove them, s = &quot;baab&quot;.
-- Take prefix = &quot;b&quot; and suffix = &quot;b&quot; and remove them, s = &quot;aa&quot;.
-- Take prefix = &quot;a&quot; and suffix = &quot;a&quot; and remove them, s = &quot;&quot;.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabccabba&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> An optimal sequence of operations is:
-- Take prefix = &quot;aa&quot; and suffix = &quot;a&quot; and remove them, s = &quot;bccabb&quot;.
-- Take prefix = &quot;b&quot; and suffix = &quot;bb&quot; and remove them, s = &quot;cca&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> only consists of characters <code>&#39;a&#39;</code>, <code>&#39;b&#39;</code>, and <code>&#39;c&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If both ends have distinct characters, no more operations can be made. Otherwise, the only operation is to remove all of the same characters from both ends. We will do this as many times as we can.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Note that if the length is equal 1 the answer is 1
-</details>
diff --git a/problems/minimum-limit-of-balls-in-a-bag/README.md b/problems/minimum-limit-of-balls-in-a-bag/README.md
deleted file mode 100644
index 85b5b54ac..000000000
--- a/problems/minimum-limit-of-balls-in-a-bag/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-number-of-homogenous-substrings "Count Number of Homogenous Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-degree-of-a-connected-trio-in-a-graph "Minimum Degree of a Connected Trio in a Graph")
-
-## [1760. Minimum Limit of Balls in a Bag (Medium)](https://leetcode.com/problems/minimum-limit-of-balls-in-a-bag "袋子里最少数目的球")
-
-<p>You are given an integer array <code>nums</code> where the <code>i<sup>th</sup></code> bag contains <code>nums[i]</code> balls. You are also given an integer <code>maxOperations</code>.</p>
-
-<p>You can perform the following operation at most <code>maxOperations</code> times:</p>
-
-<ul>
-	<li>Take any bag of balls and divide it into two new bags with a <strong>positive </strong>number of balls.
-	<ul>
-		<li>For example, a bag of <code>5</code> balls can become two new bags of <code>1</code> and <code>4</code> balls, or two new bags of <code>2</code> and <code>3</code> balls.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Your penalty is the <strong>maximum</strong> number of balls in a bag. You want to <strong>minimize</strong> your penalty after the operations.</p>
-
-<p>Return <em>the minimum possible penalty&nbsp;after performing the operations</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9], maxOperations = 2
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-- Divide the bag with 9 balls into two bags of sizes 6 and 3. [<strong><u>9</u></strong>] -&gt; [6,3].
-- Divide the bag with 6 balls into two bags of sizes 3 and 3. [<strong><u>6</u></strong>,3] -&gt; [3,3,3].
-The bag with the most number of balls has 3 balls, so your penalty is 3 and you should return 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,4,8,2], maxOperations = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-- Divide the bag with 8 balls into two bags of sizes 4 and 4. [2,4,<strong><u>8</u></strong>,2] -&gt; [2,4,4,4,2].
-- Divide the bag with 4 balls into two bags of sizes 2 and 2. [2,<strong><u>4</u></strong>,4,4,2] -&gt; [2,2,2,4,4,2].
-- Divide the bag with 4 balls into two bags of sizes 2 and 2. [2,2,2,<strong><u>4</u></strong>,4,2] -&gt; [2,2,2,2,2,4,2].
-- Divide the bag with 4 balls into two bags of sizes 2 and 2. [2,2,2,2,2,<strong><u>4</u></strong>,2] -&gt; [2,2,2,2,2,2,2,2].
-The bag with the most number of balls has 2 balls, so your penalty is 2 an you should return 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,17], maxOperations = 2
-<strong>Output:</strong> 7
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= maxOperations, nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's change the question if we know the maximum size of a bag what is the minimum number of bags you can make
-</details>
-
-<details>
-<summary>Hint 2</summary>
-note that as the maximum size increases the minimum number of bags decreases so we can binary search the maximum size
-</details>
diff --git a/problems/minimum-moves-to-convert-string/README.md b/problems/minimum-moves-to-convert-string/README.md
deleted file mode 100644
index b05b55634..000000000
--- a/problems/minimum-moves-to-convert-string/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../low-quality-problems "Low-Quality Problems")
-　　　　　　　　　　　　　　　　
-[Next >](../find-missing-observations "Find Missing Observations")
-
-## [2027. Minimum Moves to Convert String (Easy)](https://leetcode.com/problems/minimum-moves-to-convert-string "转换字符串的最少操作次数")
-
-<p>You are given a string <code>s</code> consisting of <code>n</code> characters which are either <code>&#39;X&#39;</code> or <code>&#39;O&#39;</code>.</p>
-
-<p>A <strong>move</strong> is defined as selecting <strong>three</strong> <strong>consecutive characters</strong> of <code>s</code> and converting them to <code>&#39;O&#39;</code>. Note that if a move is applied to the character <code>&#39;O&#39;</code>, it will stay the <strong>same</strong>.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of moves required so that all the characters of </em><code>s</code><em> are converted to </em><code>&#39;O&#39;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;XXX&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> <u>XXX</u> -&gt; OOO
-We select all the 3 characters and convert them in one move.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;XXOX&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> <u>XXO</u>X -&gt; O<u>OOX</u> -&gt; OOOO
-We select the first 3 characters in the first move, and convert them to <code>&#39;O&#39;</code>.
-Then we select the last 3 characters and convert them so that the final string contains all <code>&#39;O&#39;</code>s.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;OOOO&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no <code>&#39;X&#39;s</code> in <code>s</code> to convert.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s[i]</code> is either <code>&#39;X&#39;</code> or <code>&#39;O&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the smallest substring you need to consider at a time.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try delaying a move as long as possible.
-</details>
diff --git a/problems/minimum-moves-to-equal-array-elements-ii/README.md b/problems/minimum-moves-to-equal-array-elements-ii/README.md
deleted file mode 100644
index 93facd4a6..000000000
--- a/problems/minimum-moves-to-equal-array-elements-ii/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../hamming-distance "Hamming Distance")
-　　　　　　　　　　　　　　　　
-[Next >](../island-perimeter "Island Perimeter")
-
-## [462. Minimum Moves to Equal Array Elements II (Medium)](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii "最少移动次数使数组元素相等 II")
-
-<p>Given an integer array <code>nums</code> of size <code>n</code>, return <em>the minimum number of moves required to make all array elements equal</em>.</p>
-
-<p>In one move, you can increment or decrement an element of the array by <code>1</code>.</p>
-
-<p>Test cases are designed so that the answer will fit in a <strong>32-bit</strong> integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-Only two moves are needed (remember each move increments or decrements one element):
-[<u>1</u>,2,3]  =&gt;  [2,2,<u>3</u>]  =&gt;  [2,2,2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,10,2,9]
-<strong>Output:</strong> 16
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Best Meeting Point](../best-meeting-point) (Hard)
-  1. [Minimum Moves to Equal Array Elements](../minimum-moves-to-equal-array-elements) (Easy)
diff --git a/problems/minimum-moves-to-equal-array-elements-ii/minimum_moves_to_equal_array_elements_ii.go b/problems/minimum-moves-to-equal-array-elements-ii/minimum_moves_to_equal_array_elements_ii.go
deleted file mode 100644
index 3d72af8ac..000000000
--- a/problems/minimum-moves-to-equal-array-elements-ii/minimum_moves_to_equal_array_elements_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem462
diff --git a/problems/minimum-moves-to-equal-array-elements-ii/minimum_moves_to_equal_array_elements_ii_test.go b/problems/minimum-moves-to-equal-array-elements-ii/minimum_moves_to_equal_array_elements_ii_test.go
deleted file mode 100644
index 3d72af8ac..000000000
--- a/problems/minimum-moves-to-equal-array-elements-ii/minimum_moves_to_equal_array_elements_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem462
diff --git a/problems/minimum-moves-to-equal-array-elements/README.md b/problems/minimum-moves-to-equal-array-elements/README.md
deleted file mode 100644
index b830f1c85..000000000
--- a/problems/minimum-moves-to-equal-array-elements/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-arrows-to-burst-balloons "Minimum Number of Arrows to Burst Balloons")
-　　　　　　　　　　　　　　　　
-[Next >](../4sum-ii "4Sum II")
-
-## [453. Minimum Moves to Equal Array Elements (Medium)](https://leetcode.com/problems/minimum-moves-to-equal-array-elements "最小操作次数使数组元素相等")
-
-<p>Given an integer array <code>nums</code> of size <code>n</code>, return <em>the minimum number of moves required to make all array elements equal</em>.</p>
-
-<p>In one move, you can increment <code>n - 1</code> elements of the array by <code>1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Only three moves are needed (remember each move increments two elements):
-[1,2,3]  =&gt;  [2,3,3]  =&gt;  [3,4,3]  =&gt;  [4,4,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li>The answer is guaranteed to fit in a <strong>32-bit</strong> integer.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Minimum Moves to Equal Array Elements II](../minimum-moves-to-equal-array-elements-ii) (Medium)
diff --git a/problems/minimum-moves-to-equal-array-elements/minimum_moves_to_equal_array_elements.go b/problems/minimum-moves-to-equal-array-elements/minimum_moves_to_equal_array_elements.go
deleted file mode 100644
index c8f837ede..000000000
--- a/problems/minimum-moves-to-equal-array-elements/minimum_moves_to_equal_array_elements.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem453
-
-func minMoves(nums []int) int {
-	sum, min, n := 0, nums[0], len(nums)
-	for _, num := range nums {
-		sum += num
-		if min > num {
-			min = num
-		}
-	}
-	return sum - n*min
-}
diff --git a/problems/minimum-moves-to-equal-array-elements/minimum_moves_to_equal_array_elements_test.go b/problems/minimum-moves-to-equal-array-elements/minimum_moves_to_equal_array_elements_test.go
deleted file mode 100644
index e98692c00..000000000
--- a/problems/minimum-moves-to-equal-array-elements/minimum_moves_to_equal_array_elements_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem453
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMinMoves(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3},
-			want: 3,
-		},
-		{
-			in:   []int{5, 3, 1},
-			want: 6,
-		},
-	}
-	for _, tt := range tests {
-		got := minMoves(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/minimum-moves-to-make-array-complementary/README.md b/problems/minimum-moves-to-make-array-complementary/README.md
deleted file mode 100644
index bac1b8a62..000000000
--- a/problems/minimum-moves-to-make-array-complementary/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-most-competitive-subsequence "Find the Most Competitive Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../minimize-deviation-in-array "Minimize Deviation in Array")
-
-## [1674. Minimum Moves to Make Array Complementary (Medium)](https://leetcode.com/problems/minimum-moves-to-make-array-complementary "使数组互补的最少操作次数")
-
-<p>You are given an integer array <code>nums</code> of <strong>even</strong> length <code>n</code> and an integer <code>limit</code>. In one move, you can replace any integer from <code>nums</code> with another integer between <code>1</code> and <code>limit</code>, inclusive.</p>
-
-<p>The array <code>nums</code> is <strong>complementary</strong> if for all indices <code>i</code> (<strong>0-indexed</strong>), <code>nums[i] + nums[n - 1 - i]</code> equals the same number. For example, the array <code>[1,2,3,4]</code> is complementary because for all indices <code>i</code>, <code>nums[i] + nums[n - 1 - i] = 5</code>.</p>
-
-<p>Return the <em><strong>minimum</strong> number of moves required to make </em><code>nums</code><em> <strong>complementary</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,4,3], limit = 4
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> In 1 move, you can change nums to [1,2,<u>2</u>,3] (underlined elements are changed).
-nums[0] + nums[3] = 1 + 3 = 4.
-nums[1] + nums[2] = 2 + 2 = 4.
-nums[2] + nums[1] = 2 + 2 = 4.
-nums[3] + nums[0] = 3 + 1 = 4.
-Therefore, nums[i] + nums[n-1-i] = 4 for every i, so nums is complementary.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,2,1], limit = 2
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> In 2 moves, you can change nums to [<u>2</u>,2,2,<u>2</u>]. You cannot change any number to 3 since 3 &gt; limit.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1,2], limit = 2
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> nums is already complementary.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>2 &lt;= n&nbsp;&lt;=&nbsp;10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i]&nbsp;&lt;= limit &lt;=&nbsp;10<sup>5</sup></code></li>
-	<li><code>n</code> is even.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given a target sum x, each pair of nums[i] and nums[n-1-i] would either need 0, 1, or 2 modifications.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you find the optimal target sum x value such that the sum of modifications is minimized?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Create a difference array to efficiently sum all the modifications.
-</details>
diff --git a/problems/minimum-moves-to-move-a-box-to-their-target-location/README.md b/problems/minimum-moves-to-move-a-box-to-their-target-location/README.md
deleted file mode 100644
index 34b543908..000000000
--- a/problems/minimum-moves-to-move-a-box-to-their-target-location/README.md
+++ /dev/null
@@ -1,95 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../greatest-sum-divisible-by-three "Greatest Sum Divisible by Three")
-　　　　　　　　　　　　　　　　
-[Next >](../page-recommendations "Page Recommendations")
-
-## [1263. Minimum Moves to Move a Box to Their Target Location (Hard)](https://leetcode.com/problems/minimum-moves-to-move-a-box-to-their-target-location "推箱子")
-
-<p>A storekeeper is a game in which the player pushes boxes around in a warehouse trying to get them to target locations.</p>
-
-<p>The game is represented by an <code>m x n</code> grid of characters <code>grid</code> where each element is a wall, floor, or box.</p>
-
-<p>Your task is to move the box <code>&#39;B&#39;</code> to the target position <code>&#39;T&#39;</code> under the following rules:</p>
-
-<ul>
-	<li>The character <code>&#39;S&#39;</code> represents the player. The player can move up, down, left, right in <code>grid</code> if it is a floor (empty cell).</li>
-	<li>The character <code>&#39;.&#39;</code> represents the floor which means a free cell to walk.</li>
-	<li>The character <code>&#39;#&#39; </code>represents the wall which means an obstacle (impossible to walk there).</li>
-	<li>There is only one box <code>&#39;B&#39;</code> and one target cell <code>&#39;T&#39;</code> in the <code>grid</code>.</li>
-	<li>The box can be moved to an adjacent free cell by standing next to the box and then moving in the direction of the box. This is a <strong>push</strong>.</li>
-	<li>The player cannot walk through the box.</li>
-</ul>
-
-<p>Return <em>the minimum number of <strong>pushes</strong> to move the box to the target</em>. If there is no way to reach the target, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/06/sample_1_1620.png" style="width: 500px; height: 335px;" />
-<pre>
-<strong>Input:</strong> grid = [[&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;T&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;.&quot;,&quot;.&quot;,&quot;B&quot;,&quot;.&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;.&quot;,&quot;#&quot;,&quot;#&quot;,&quot;.&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;S&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We return only the number of times the box is pushed.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;T&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;.&quot;,&quot;.&quot;,&quot;B&quot;,&quot;.&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;.&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;S&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;]]
-<strong>Output:</strong> -1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;T&quot;,&quot;.&quot;,&quot;.&quot;,&quot;#&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;.&quot;,&quot;#&quot;,&quot;B&quot;,&quot;.&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;S&quot;,&quot;#&quot;],
-               [&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;#&quot;]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> push the box down, left, left, up and up.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 20</code></li>
-	<li><code>grid</code> contains only characters <code>&#39;.&#39;</code>, <code>&#39;#&#39;</code>, <code>&#39;S&#39;</code>, <code>&#39;T&#39;</code>, or <code>&#39;B&#39;</code>.</li>
-	<li>There is only one character <code>&#39;S&#39;</code>, <code>&#39;B&#39;</code>, and <code>&#39;T&#39;</code> in the <code>grid</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We represent the search state as (player_row, player_col, box_row, box_col).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You need to count only the number of pushes. Then inside of your BFS check if the box could be pushed (in any direction) given the current position of the player.
-</details>
diff --git a/problems/minimum-moves-to-reach-target-score/README.md b/problems/minimum-moves-to-reach-target-score/README.md
deleted file mode 100644
index 03f9395f4..000000000
--- a/problems/minimum-moves-to-reach-target-score/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../divide-a-string-into-groups-of-size-k "Divide a String Into Groups of Size k")
-　　　　　　　　　　　　　　　　
-[Next >](../solving-questions-with-brainpower "Solving Questions With Brainpower")
-
-## [2139. Minimum Moves to Reach Target Score (Medium)](https://leetcode.com/problems/minimum-moves-to-reach-target-score "得到目标值的最少行动次数")
-
-<p>You are playing a game with integers. You start with the integer <code>1</code> and you want to reach the integer <code>target</code>.</p>
-
-<p>In one move, you can either:</p>
-
-<ul>
-	<li><strong>Increment</strong> the current integer by one (i.e., <code>x = x + 1</code>).</li>
-	<li><strong>Double</strong> the current integer (i.e., <code>x = 2 * x</code>).</li>
-</ul>
-
-<p>You can use the <strong>increment</strong> operation <strong>any</strong> number of times, however, you can only use the <strong>double</strong> operation <strong>at most</strong> <code>maxDoubles</code> times.</p>
-
-<p>Given the two integers <code>target</code> and <code>maxDoubles</code>, return <em>the minimum number of moves needed to reach </em><code>target</code><em> starting with </em><code>1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 5, maxDoubles = 0
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Keep incrementing by 1 until you reach target.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 19, maxDoubles = 2
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> Initially, x = 1
-Increment 3 times so x = 4
-Double once so x = 8
-Increment once so x = 9
-Double again so x = 18
-Increment once so x = 19
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 10, maxDoubles = 4
-<strong>Output:</strong> 4
-<strong>Explanation:</strong><b> </b>Initially, x = 1
-Increment once so x = 2
-Double once so x = 4
-Increment once so x = 5
-Double again so x = 10
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= target &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= maxDoubles &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Solve the opposite problem: start at the given score and move to 1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-It is better to use the move of the second type once we can to lose more scores fast.
-</details>
diff --git a/problems/minimum-moves-to-reach-target-with-rotations/README.md b/problems/minimum-moves-to-reach-target-with-rotations/README.md
deleted file mode 100644
index afdb6a02c..000000000
--- a/problems/minimum-moves-to-reach-target-with-rotations/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-all-adjacent-duplicates-in-string-ii "Remove All Adjacent Duplicates in String II")
-　　　　　　　　　　　　　　　　
-[Next >](../queries-quality-and-percentage "Queries Quality and Percentage")
-
-## [1210. Minimum Moves to Reach Target with Rotations (Hard)](https://leetcode.com/problems/minimum-moves-to-reach-target-with-rotations "穿过迷宫的最少移动次数")
-
-<p>In an&nbsp;<code>n*n</code>&nbsp;grid, there is a snake that spans 2 cells and starts moving from the top left corner at <code>(0, 0)</code> and <code>(0, 1)</code>. The grid has empty cells represented by zeros and blocked cells represented by ones. The snake wants to reach the lower right corner at&nbsp;<code>(n-1, n-2)</code>&nbsp;and&nbsp;<code>(n-1, n-1)</code>.</p>
-
-<p>In one move the snake can:</p>
-
-<ul>
-	<li>Move one cell to the right&nbsp;if there are no blocked cells there. This move keeps the horizontal/vertical position of the snake as it is.</li>
-	<li>Move down one cell&nbsp;if there are no blocked cells there. This move keeps the horizontal/vertical position of the snake as it is.</li>
-	<li>Rotate clockwise if it&#39;s in a horizontal position and the two cells under it are both empty. In that case the snake moves from&nbsp;<code>(r, c)</code>&nbsp;and&nbsp;<code>(r, c+1)</code>&nbsp;to&nbsp;<code>(r, c)</code>&nbsp;and&nbsp;<code>(r+1, c)</code>.<br />
-	<img alt="" src="https://assets.leetcode.com/uploads/2019/09/24/image-2.png" style="width: 300px; height: 134px;" /></li>
-	<li>Rotate counterclockwise&nbsp;if it&#39;s in a vertical position and the two cells to its right are both empty. In that case the snake moves from&nbsp;<code>(r, c)</code>&nbsp;and&nbsp;<code>(r+1, c)</code>&nbsp;to&nbsp;<code>(r, c)</code>&nbsp;and&nbsp;<code>(r, c+1)</code>.<br />
-	<img alt="" src="https://assets.leetcode.com/uploads/2019/09/24/image-1.png" style="width: 300px; height: 121px;" /></li>
-</ul>
-
-<p>Return the minimum number of moves to reach the target.</p>
-
-<p>If there is no way to reach the target, return&nbsp;<code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/09/24/image.png" style="width: 400px; height: 439px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0,0,0,0,0,1],
-               [1,1,0,0,1,0],
-&nbsp;              [0,0,0,0,1,1],
-&nbsp;              [0,0,1,0,1,0],
-&nbsp;              [0,1,1,0,0,0],
-&nbsp;              [0,1,1,0,0,0]]
-<strong>Output:</strong> 11
-<strong>Explanation:
-</strong>One possible solution is [right, right, rotate clockwise, right, down, down, down, down, rotate counterclockwise, right, down].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0,0,1,1,1,1],
-&nbsp;              [0,0,0,0,1,1],
-&nbsp;              [1,1,0,0,0,1],
-&nbsp;              [1,1,1,0,0,1],
-&nbsp;              [1,1,1,0,0,1],
-&nbsp;              [1,1,1,0,0,0]]
-<strong>Output:</strong> 9
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 100</code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;= 1</code></li>
-	<li>It is guaranteed that the snake starts at empty cells.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use BFS to find the answer.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The state of the BFS is the position (x, y) along with a binary value that specifies if the position is horizontal or vertical.
-</details>
diff --git a/problems/minimum-non-zero-product-of-the-array-elements/README.md b/problems/minimum-non-zero-product-of-the-array-elements/README.md
deleted file mode 100644
index 9652b9b39..000000000
--- a/problems/minimum-non-zero-product-of-the-array-elements/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../array-with-elements-not-equal-to-average-of-neighbors "Array With Elements Not Equal to Average of Neighbors")
-　　　　　　　　　　　　　　　　
-[Next >](../last-day-where-you-can-still-cross "Last Day Where You Can Still Cross")
-
-## [1969. Minimum Non-Zero Product of the Array Elements (Medium)](https://leetcode.com/problems/minimum-non-zero-product-of-the-array-elements "数组元素的最小非零乘积")
-
-<p>You are given a positive integer <code>p</code>. Consider an array <code>nums</code> (<strong>1-indexed</strong>) that consists of the integers in the <strong>inclusive</strong> range <code>[1, 2<sup>p</sup> - 1]</code> in their binary representations. You are allowed to do the following operation <strong>any</strong> number of times:</p>
-
-<ul>
-	<li>Choose two elements <code>x</code> and <code>y</code> from <code>nums</code>.</li>
-	<li>Choose a bit in <code>x</code> and swap it with its corresponding bit in <code>y</code>. Corresponding bit refers to the bit that is in the <strong>same position</strong> in the other integer.</li>
-</ul>
-
-<p>For example, if <code>x = 11<u>0</u>1</code> and <code>y = 00<u>1</u>1</code>, after swapping the <code>2<sup>nd</sup></code> bit from the right, we have <code>x = 11<u>1</u>1</code> and <code>y = 00<u>0</u>1</code>.</p>
-
-<p>Find the <strong>minimum non-zero</strong> product of <code>nums</code> after performing the above operation <strong>any</strong> number of times. Return <em>this product</em><em> <strong>modulo</strong> </em><code>10<sup>9</sup> + 7</code>.</p>
-
-<p><strong>Note:</strong> The answer should be the minimum product <strong>before</strong> the modulo operation is done.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> p = 1
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> nums = [1].
-There is only one element, so the product equals that element.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> p = 2
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> nums = [01, 10, 11].
-Any swap would either make the product 0 or stay the same.
-Thus, the array product of 1 * 2 * 3 = 6 is already minimized.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> p = 3
-<strong>Output:</strong> 1512
-<strong>Explanation:</strong> nums = [001, 010, 011, 100, 101, 110, 111]
-- In the first operation we can swap the leftmost bit of the second and fifth elements.
-    - The resulting array is [001, <u>1</u>10, 011, 100, <u>0</u>01, 110, 111].
-- In the second operation we can swap the middle bit of the third and fourth elements.
-    - The resulting array is [001, 110, 0<u>0</u>1, 1<u>1</u>0, 001, 110, 111].
-The array product is 1 * 6 * 1 * 6 * 1 * 6 * 7 = 1512, which is the minimum possible product.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= p &lt;= 60</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to minimize each element by swapping bits with any of the elements after it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you swap out all the 1s in some element, this will lead to a product of zero.
-</details>
diff --git a/problems/minimum-number-of-arrows-to-burst-balloons/README.md b/problems/minimum-number-of-arrows-to-burst-balloons/README.md
deleted file mode 100644
index 592359a87..000000000
--- a/problems/minimum-number-of-arrows-to-burst-balloons/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-characters-by-frequency "Sort Characters By Frequency")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-moves-to-equal-array-elements "Minimum Moves to Equal Array Elements")
-
-## [452. Minimum Number of Arrows to Burst Balloons (Medium)](https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons "用最少数量的箭引爆气球")
-
-<p>There are some spherical balloons taped onto a flat wall that represents the XY-plane. The balloons are represented as a 2D integer array <code>points</code> where <code>points[i] = [x<sub>start</sub>, x<sub>end</sub>]</code> denotes a balloon whose <strong>horizontal diameter</strong> stretches between <code>x<sub>start</sub></code> and <code>x<sub>end</sub></code>. You do not know the exact y-coordinates of the balloons.</p>
-
-<p>Arrows can be shot up <strong>directly vertically</strong> (in the positive y-direction) from different points along the x-axis. A balloon with <code>x<sub>start</sub></code> and <code>x<sub>end</sub></code> is <strong>burst</strong> by an arrow shot at <code>x</code> if <code>x<sub>start</sub> &lt;= x &lt;= x<sub>end</sub></code>. There is <strong>no limit</strong> to the number of arrows that can be shot. A shot arrow keeps traveling up infinitely, bursting any balloons in its path.</p>
-
-<p>Given the array <code>points</code>, return <em>the <strong>minimum</strong> number of arrows that must be shot to burst all balloons</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[10,16],[2,8],[1,6],[7,12]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The balloons can be burst by 2 arrows:
-- Shoot an arrow at x = 6, bursting the balloons [2,8] and [1,6].
-- Shoot an arrow at x = 11, bursting the balloons [10,16] and [7,12].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[1,2],[3,4],[5,6],[7,8]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> One arrow needs to be shot for each balloon for a total of 4 arrows.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[1,2],[2,3],[3,4],[4,5]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The balloons can be burst by 2 arrows:
-- Shoot an arrow at x = 2, bursting the balloons [1,2] and [2,3].
-- Shoot an arrow at x = 4, bursting the balloons [3,4] and [4,5].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= points.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>-2<sup>31</sup> &lt;= x<sub>start</sub> &lt; x<sub>end</sub> &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Meeting Rooms II](../meeting-rooms-ii) (Medium)
-  1. [Non-overlapping Intervals](../non-overlapping-intervals) (Medium)
diff --git a/problems/minimum-number-of-arrows-to-burst-balloons/minimum_number_of_arrows_to_burst_balloons.go b/problems/minimum-number-of-arrows-to-burst-balloons/minimum_number_of_arrows_to_burst_balloons.go
deleted file mode 100644
index c83237294..000000000
--- a/problems/minimum-number-of-arrows-to-burst-balloons/minimum_number_of_arrows_to_burst_balloons.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem452
diff --git a/problems/minimum-number-of-arrows-to-burst-balloons/minimum_number_of_arrows_to_burst_balloons_test.go b/problems/minimum-number-of-arrows-to-burst-balloons/minimum_number_of_arrows_to_burst_balloons_test.go
deleted file mode 100644
index c83237294..000000000
--- a/problems/minimum-number-of-arrows-to-burst-balloons/minimum_number_of_arrows_to_burst_balloons_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem452
diff --git a/problems/minimum-number-of-buckets-required-to-collect-rainwater-from-houses/README.md b/problems/minimum-number-of-buckets-required-to-collect-rainwater-from-houses/README.md
deleted file mode 100644
index 8a0798f2f..000000000
--- a/problems/minimum-number-of-buckets-required-to-collect-rainwater-from-houses/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-common-words-with-one-occurrence "Count Common Words With One Occurrence")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-homecoming-of-a-robot-in-a-grid "Minimum Cost Homecoming of a Robot in a Grid")
-
-## [2086. Minimum Number of Buckets Required to Collect Rainwater from Houses (Medium)](https://leetcode.com/problems/minimum-number-of-buckets-required-to-collect-rainwater-from-houses "从房屋收集雨水需要的最少水桶数")
-
-<p>You are given a <b>0-index</b><strong>ed</strong> string <code>street</code>. Each character in <code>street</code> is either <code>&#39;H&#39;</code> representing a house or <code>&#39;.&#39;</code> representing an empty space.</p>
-
-<p>You can place buckets on the <strong>empty spaces</strong> to collect rainwater that falls from the adjacent houses. The rainwater from a house at index <code>i</code> is collected if a bucket is placed at index <code>i - 1</code> <strong>and/or</strong> index <code>i + 1</code>. A single bucket, if placed adjacent to two houses, can collect the rainwater from <strong>both</strong> houses.</p>
-
-<p>Return <em>the <strong>minimum </strong>number of buckets needed so that for <strong>every</strong> house, there is <strong>at least</strong> one bucket collecting rainwater from it, or </em><code>-1</code><em> if it is impossible.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> street = &quot;H..H&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-We can put buckets at index 1 and index 2.
-&quot;H..H&quot; -&gt; &quot;HBBH&quot; (&#39;B&#39; denotes where a bucket is placed).
-The house at index 0 has a bucket to its right, and the house at index 3 has a bucket to its left.
-Thus, for every house, there is at least one bucket collecting rainwater from it.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> street = &quot;.H.H.&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-We can put a bucket at index 2.
-&quot;.H.H.&quot; -&gt; &quot;.HBH.&quot; (&#39;B&#39; denotes where a bucket is placed).
-The house at index 1 has a bucket to its right, and the house at index 3 has a bucket to its left.
-Thus, for every house, there is at least one bucket collecting rainwater from it.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> street = &quot;.HHH.&quot;
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>
-There is no empty space to place a bucket to collect the rainwater from the house at index 2.
-Thus, it is impossible to collect the rainwater from all the houses.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= street.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>street[i]</code> is either<code>&#39;H&#39;</code> or <code>&#39;.&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-When is it impossible to collect the rainwater from all the houses?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When one or more houses do not have an empty space adjacent to it.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Assuming the rainwater from all previous houses is collected. If there is a house at index i and you are able to place a bucket at index i - 1 or i + 1, where should you put it?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-It is always better to place a bucket at index i + 1 because it can collect the rainwater from the next house as well.
-</details>
diff --git a/problems/minimum-number-of-days-to-disconnect-island/README.md b/problems/minimum-number-of-days-to-disconnect-island/README.md
deleted file mode 100644
index 2f96201d0..000000000
--- a/problems/minimum-number-of-days-to-disconnect-island/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-length-of-subarray-with-positive-product "Maximum Length of Subarray With Positive Product")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-reorder-array-to-get-same-bst "Number of Ways to Reorder Array to Get Same BST")
-
-## [1568. Minimum Number of Days to Disconnect Island (Hard)](https://leetcode.com/problems/minimum-number-of-days-to-disconnect-island "使陆地分离的最少天数")
-
-<p>You are given an <code>m x n</code> binary grid <code>grid</code> where <code>1</code> represents land and <code>0</code> represents water. An <strong>island</strong> is a maximal <strong>4-directionally</strong> (horizontal or vertical) connected group of <code>1</code>&#39;s.</p>
-
-<p>The grid is said to be <strong>connected</strong> if we have <strong>exactly one island</strong>, otherwise is said <strong>disconnected</strong>.</p>
-
-<p>In one day, we are allowed to change <strong>any </strong>single land cell <code>(1)</code> into a water cell <code>(0)</code>.</p>
-
-<p>Return <em>the minimum number of days to disconnect the grid</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/24/land1.jpg" style="width: 500px; height: 169px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1,1,0],[0,1,1,0],[0,0,0,0]]
-
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We need at least 2 days to get a disconnected grid.
-Change land grid[1][1] and grid[0][2] to water and get 2 disconnected island.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/24/land2.jpg" style="width: 404px; height: 85px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,1]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Grid of full water is also disconnected ([[1,1]] -&gt; [[0,0]]), 0 islands.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 30</code></li>
-	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Strongly Connected Component](../../tag/strongly-connected-component/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Return 0 if the grid is already disconnected.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Return 1 if changing a single land to water disconnect the island.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Otherwise return 2.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-We can disconnect the grid within at most 2 days.
-</details>
diff --git a/problems/minimum-number-of-days-to-eat-n-oranges/README.md b/problems/minimum-number-of-days-to-eat-n-oranges/README.md
deleted file mode 100644
index ef9a3d0c3..000000000
--- a/problems/minimum-number-of-days-to-eat-n-oranges/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../magnetic-force-between-two-balls "Magnetic Force Between Two Balls")
-　　　　　　　　　　　　　　　　
-[Next >](../strings-differ-by-one-character "Strings Differ by One Character")
-
-## [1553. Minimum Number of Days to Eat N Oranges (Hard)](https://leetcode.com/problems/minimum-number-of-days-to-eat-n-oranges "吃掉 N 个橘子的最少天数")
-
-<p>There are <code>n</code> oranges in the kitchen and you decided to eat some of these oranges every day as follows:</p>
-
-<ul>
-	<li>Eat one orange.</li>
-	<li>If the number of remaining oranges <code>n</code> is divisible by <code>2</code> then you can eat <code>n / 2</code> oranges.</li>
-	<li>If the number of remaining oranges <code>n</code> is divisible by <code>3</code> then you can eat <code>2 * (n / 3)</code> oranges.</li>
-</ul>
-
-<p>You can only choose one of the actions per day.</p>
-
-<p>Given the integer <code>n</code>, return <em>the minimum number of days to eat</em> <code>n</code> <em>oranges</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> You have 10 oranges.
-Day 1: Eat 1 orange,  10 - 1 = 9.  
-Day 2: Eat 6 oranges, 9 - 2*(9/3) = 9 - 6 = 3. (Since 9 is divisible by 3)
-Day 3: Eat 2 oranges, 3 - 2*(3/3) = 3 - 2 = 1. 
-Day 4: Eat the last orange  1 - 1  = 0.
-You need at least 4 days to eat the 10 oranges.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You have 6 oranges.
-Day 1: Eat 3 oranges, 6 - 6/2 = 6 - 3 = 3. (Since 6 is divisible by 2).
-Day 2: Eat 2 oranges, 3 - 2*(3/3) = 3 - 2 = 1. (Since 3 is divisible by 3)
-Day 3: Eat the last orange  1 - 1  = 0.
-You need at least 3 days to eat the 6 oranges.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-In each step, choose between 2 options:
-minOranges = 1 + min( (n%2) + f(n/2), (n%3) + f(n/3) )
-where f(n) is the minimum number of days to eat n oranges.
-</details>
diff --git a/problems/minimum-number-of-days-to-make-m-bouquets/README.md b/problems/minimum-number-of-days-to-make-m-bouquets/README.md
deleted file mode 100644
index 23c7493b3..000000000
--- a/problems/minimum-number-of-days-to-make-m-bouquets/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../least-number-of-unique-integers-after-k-removals "Least Number of Unique Integers after K Removals")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-ancestor-of-a-tree-node "Kth Ancestor of a Tree Node")
-
-## [1482. Minimum Number of Days to Make m Bouquets (Medium)](https://leetcode.com/problems/minimum-number-of-days-to-make-m-bouquets "制作 m 束花所需的最少天数")
-
-<p>You are given an integer array <code>bloomDay</code>, an integer <code>m</code> and an integer <code>k</code>.</p>
-
-<p>You want to make <code>m</code> bouquets. To make a bouquet, you need to use <code>k</code> <strong>adjacent flowers</strong> from the garden.</p>
-
-<p>The garden consists of <code>n</code> flowers, the <code>i<sup>th</sup></code> flower will bloom in the <code>bloomDay[i]</code> and then can be used in <strong>exactly one</strong> bouquet.</p>
-
-<p>Return <em>the minimum number of days you need to wait to be able to make </em><code>m</code><em> bouquets from the garden</em>. If it is impossible to make m bouquets return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> bloomDay = [1,10,3,10,2], m = 3, k = 1
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Let us see what happened in the first three days. x means flower bloomed and _ means flower did not bloom in the garden.
-We need 3 bouquets each should contain 1 flower.
-After day 1: [x, _, _, _, _]   // we can only make one bouquet.
-After day 2: [x, _, _, _, x]   // we can only make two bouquets.
-After day 3: [x, _, x, _, x]   // we can make 3 bouquets. The answer is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> bloomDay = [1,10,3,10,2], m = 3, k = 2
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> We need 3 bouquets each has 2 flowers, that means we need 6 flowers. We only have 5 flowers so it is impossible to get the needed bouquets and we return -1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> bloomDay = [7,7,7,7,12,7,7], m = 2, k = 3
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> We need 2 bouquets each should have 3 flowers.
-Here is the garden after the 7 and 12 days:
-After day 7: [x, x, x, x, _, x, x]
-We can make one bouquet of the first three flowers that bloomed. We cannot make another bouquet from the last three flowers that bloomed because they are not adjacent.
-After day 12: [x, x, x, x, x, x, x]
-It is obvious that we can make two bouquets in different ways.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>bloomDay.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= bloomDay[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= m &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= k &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Maximize the Confusion of an Exam](../maximize-the-confusion-of-an-exam) (Medium)
-  1. [Earliest Possible Day of Full Bloom](../earliest-possible-day-of-full-bloom) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If we can make m or more bouquets at day x, then we can still make m or more bouquets at any day y > x.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can check easily if we can make enough bouquets at day x if we can get group adjacent flowers at day x.
-</details>
diff --git a/problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix/README.md b/problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix/README.md
deleted file mode 100644
index 1dc73d265..000000000
--- a/problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-smallest-divisor-given-a-threshold "Find the Smallest Divisor Given a Threshold")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-start-and-end-number-of-continuous-ranges "Find the Start and End Number of Continuous Ranges")
-
-## [1284. Minimum Number of Flips to Convert Binary Matrix to Zero Matrix (Hard)](https://leetcode.com/problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix "转化为全零矩阵的最少反转次数")
-
-<p>Given a <code>m x n</code> binary matrix <code>mat</code>. In one step, you can choose one cell and flip it and all the four neighbors of it if they exist (Flip is changing <code>1</code> to <code>0</code> and <code>0</code> to <code>1</code>). A pair of cells are called neighbors if they share one edge.</p>
-
-<p>Return the <em>minimum number of steps</em> required to convert <code>mat</code> to a zero matrix or <code>-1</code> if you cannot.</p>
-
-<p>A <strong>binary matrix</strong> is a matrix with all cells equal to <code>0</code> or <code>1</code> only.</p>
-
-<p>A <strong>zero matrix</strong> is a matrix with all cells equal to <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/28/matrix.png" style="width: 409px; height: 86px;" />
-<pre>
-<strong>Input:</strong> mat = [[0,0],[0,1]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> One possible solution is to flip (1, 0) then (0, 1) and finally (1, 1) as shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[0]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Given matrix is a zero matrix. We do not need to change it.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[1,0,0],[1,0,0]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> Given matrix cannot be a zero matrix.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 3</code></li>
-	<li><code>mat[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Minimum Operations to Remove Adjacent Ones in Matrix](../minimum-operations-to-remove-adjacent-ones-in-matrix) (Hard)
-  1. [Remove All Ones With Row and Column Flips](../remove-all-ones-with-row-and-column-flips) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Flipping same index two times is like not flipping it at all. Each index can be flipped one time. Try all possible combinations. O(2^(n*m)).
-</details>
diff --git a/problems/minimum-number-of-flips-to-make-the-binary-string-alternating/README.md b/problems/minimum-number-of-flips-to-make-the-binary-string-alternating/README.md
deleted file mode 100644
index b039c7179..000000000
--- a/problems/minimum-number-of-flips-to-make-the-binary-string-alternating/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reduction-operations-to-make-the-array-elements-equal "Reduction Operations to Make the Array Elements Equal")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-space-wasted-from-packaging "Minimum Space Wasted From Packaging")
-
-## [1888. Minimum Number of Flips to Make the Binary String Alternating (Medium)](https://leetcode.com/problems/minimum-number-of-flips-to-make-the-binary-string-alternating "使二进制字符串字符交替的最少反转次数")
-
-<p>You are given a binary string <code>s</code>. You are allowed to perform two types of operations on the string in any sequence:</p>
-
-<ul>
-	<li><strong>Type-1: Remove</strong> the character at the start of the string <code>s</code> and <strong>append</strong> it to the end of the string.</li>
-	<li><strong>Type-2: Pick</strong> any character in <code>s</code> and <strong>flip</strong> its value, i.e., if its value is <code>&#39;0&#39;</code> it becomes <code>&#39;1&#39;</code> and vice-versa.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum</strong> number of <strong>type-2</strong> operations you need to perform</em> <em>such that </em><code>s</code> <em>becomes <strong>alternating</strong>.</em></p>
-
-<p>The string is called <strong>alternating</strong> if no two adjacent characters are equal.</p>
-
-<ul>
-	<li>For example, the strings <code>&quot;010&quot;</code> and <code>&quot;1010&quot;</code> are alternating, while the string <code>&quot;0100&quot;</code> is not.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;111000&quot;
-<strong>Output:</strong> 2
-<strong>Explanation</strong>: Use the first operation two times to make s = &quot;100011&quot;.
-Then, use the second operation on the third and sixth elements to make s = &quot;10<u>1</u>01<u>0</u>&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;010&quot;
-<strong>Output:</strong> 0
-<strong>Explanation</strong>: The string is already alternating.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1110&quot;
-<strong>Output:</strong> 1
-<strong>Explanation</strong>: Use the second operation on the second element to make s = &quot;1<u>0</u>10&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note what actually matters is how many 0s and 1s are in odd and even positions
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For every cyclic shift we need to count how many 0s and 1s are at each parity and convert the minimum between them for each parity
-</details>
diff --git a/problems/minimum-number-of-frogs-croaking/README.md b/problems/minimum-number-of-frogs-croaking/README.md
deleted file mode 100644
index 55866e125..000000000
--- a/problems/minimum-number-of-frogs-croaking/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../display-table-of-food-orders-in-a-restaurant "Display Table of Food Orders in a Restaurant")
-　　　　　　　　　　　　　　　　
-[Next >](../build-array-where-you-can-find-the-maximum-exactly-k-comparisons "Build Array Where You Can Find The Maximum Exactly K Comparisons")
-
-## [1419. Minimum Number of Frogs Croaking (Medium)](https://leetcode.com/problems/minimum-number-of-frogs-croaking "数青蛙")
-
-<p>You are given the string <code>croakOfFrogs</code>, which represents a combination of the string <code>&quot;croak&quot;</code> from different frogs, that is, multiple frogs can croak at the same time, so multiple <code>&quot;croak&quot;</code> are mixed.</p>
-
-<p><em>Return the minimum number of </em>different<em> frogs to finish all the croaks in the given string.</em></p>
-
-<p>A valid <code>&quot;croak&quot;</code> means a frog is printing five letters <code>&#39;c&#39;</code>, <code>&#39;r&#39;</code>, <code>&#39;o&#39;</code>, <code>&#39;a&#39;</code>, and <code>&#39;k&#39;</code> <strong>sequentially</strong>. The frogs have to print all five letters to finish a croak. If the given string is not a combination of a valid <code>&quot;croak&quot;</code> return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> croakOfFrogs = &quot;croakcroak&quot;
-<strong>Output:</strong> 1 
-<strong>Explanation:</strong> One frog yelling &quot;croak<strong>&quot;</strong> twice.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> croakOfFrogs = &quot;crcoakroak&quot;
-<strong>Output:</strong> 2 
-<strong>Explanation:</strong> The minimum number of frogs is two. 
-The first frog could yell &quot;<strong>cr</strong>c<strong>oak</strong>roak&quot;.
-The second frog could yell later &quot;cr<strong>c</strong>oak<strong>roak</strong>&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> croakOfFrogs = &quot;croakcrook&quot;
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> The given string is an invalid combination of &quot;croak<strong>&quot;</strong> from different frogs.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= croakOfFrogs.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>croakOfFrogs</code> is either <code>&#39;c&#39;</code>, <code>&#39;r&#39;</code>, <code>&#39;o&#39;</code>, <code>&#39;a&#39;</code>, or <code>&#39;k&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-keep the frequency of all characters from "croak" using a hashmap.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each character in the given string, greedily match it to a possible "croak".
-</details>
diff --git a/problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array/README.md b/problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array/README.md
deleted file mode 100644
index 48368b32a..000000000
--- a/problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-good-ways-to-split-a-string "Number of Good Ways to Split a String")
-　　　　　　　　　　　　　　　　
-[Next >](../patients-with-a-condition "Patients With a Condition")
-
-## [1526. Minimum Number of Increments on Subarrays to Form a Target Array (Hard)](https://leetcode.com/problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array "形成目标数组的子数组最少增加次数")
-
-<p>You are given an integer array <code>target</code>. You have an integer array <code>initial</code> of the same size as <code>target</code> with all elements initially zeros.</p>
-
-<p>In one operation you can choose <strong>any</strong> subarray from <code>initial</code> and increment each value by one.</p>
-
-<p>Return <em>the minimum number of operations to form a </em><code>target</code><em> array from </em><code>initial</code>.</p>
-
-<p>The test cases are generated so that the answer fits in a 32-bit integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [1,2,3,2,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We need at least 3 operations to form the target array from the initial array.
-[<strong><u>0,0,0,0,0</u></strong>] increment 1 from index 0 to 4 (inclusive).
-[1,<strong><u>1,1,1</u></strong>,1] increment 1 from index 1 to 3 (inclusive).
-[1,2,<strong><u>2</u></strong>,2,1] increment 1 at index 2.
-[1,2,3,2,1] target array is formed.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [3,1,1,2]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> [<strong><u>0,0,0,0</u></strong>] -&gt; [1,1,1,<strong><u>1</u></strong>] -&gt; [<strong><u>1</u></strong>,1,1,2] -&gt; [<strong><u>2</u></strong>,1,1,2] -&gt; [3,1,1,2]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [3,1,5,4,2]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> [<strong><u>0,0,0,0,0</u></strong>] -&gt; [<strong><u>1</u></strong>,1,1,1,1] -&gt; [<strong><u>2</u></strong>,1,1,1,1] -&gt; [3,1,<strong><u>1,1,1</u></strong>] -&gt; [3,1,<strong><u>2,2</u></strong>,2] -&gt; [3,1,<strong><u>3,3</u></strong>,2] -&gt; [3,1,<strong><u>4</u></strong>,4,2] -&gt; [3,1,5,4,2].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= target.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= target[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For a given range of values in target, an optimal strategy is to increment the entire range by the minimum value. The minimum in a range could be obtained with Range minimum query or Segment trees algorithm.
-</details>
diff --git a/problems/minimum-number-of-k-consecutive-bit-flips/README.md b/problems/minimum-number-of-k-consecutive-bit-flips/README.md
deleted file mode 100644
index 79f2de9f5..000000000
--- a/problems/minimum-number-of-k-consecutive-bit-flips/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rotting-oranges "Rotting Oranges")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-squareful-arrays "Number of Squareful Arrays")
-
-## [995. Minimum Number of K Consecutive Bit Flips (Hard)](https://leetcode.com/problems/minimum-number-of-k-consecutive-bit-flips "K 连续位的最小翻转次数")
-
-<p>You are given a binary array <code>nums</code> and an integer <code>k</code>.</p>
-
-<p>A <strong>k-bit flip</strong> is choosing a <strong>subarray</strong> of length <code>k</code> from <code>nums</code> and simultaneously changing every <code>0</code> in the subarray to <code>1</code>, and every <code>1</code> in the subarray to <code>0</code>.</p>
-
-<p>Return <em>the minimum number of <strong>k-bit flips</strong> required so that there is no </em><code>0</code><em> in the array</em>. If it is not possible, return <code>-1</code>.</p>
-
-<p>A <strong>subarray</strong> is a <strong>contiguous</strong> part of an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,0], k = 1
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Flip nums[0], then flip nums[2].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,0], k = 2
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> No matter how we flip subarrays of size 2, we cannot make the array become [1,1,1].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,0,1,0,1,1,0], k = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-Flip nums[0],nums[1],nums[2]: nums becomes [1,1,1,1,0,1,1,0]
-Flip nums[4],nums[5],nums[6]: nums becomes [1,1,1,1,1,0,0,0]
-Flip nums[5],nums[6],nums[7]: nums becomes [1,1,1,1,1,1,1,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= k &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Bulb Switcher](../bulb-switcher) (Medium)
diff --git a/problems/minimum-number-of-k-consecutive-bit-flips/minimum_number_of_k_consecutive_bit_flips.go b/problems/minimum-number-of-k-consecutive-bit-flips/minimum_number_of_k_consecutive_bit_flips.go
deleted file mode 100644
index a0b7b0095..000000000
--- a/problems/minimum-number-of-k-consecutive-bit-flips/minimum_number_of_k_consecutive_bit_flips.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem995
diff --git a/problems/minimum-number-of-lines-to-cover-points/README.md b/problems/minimum-number-of-lines-to-cover-points/README.md
deleted file mode 100644
index 582bba6e1..000000000
--- a/problems/minimum-number-of-lines-to-cover-points/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-good-people-based-on-statements "Maximum Good People Based on Statements")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-passengers-in-each-bus-ii "The Number of Passengers in Each Bus II")
-
-## [2152. Minimum Number of Lines to Cover Points (Medium)](https://leetcode.com/problems/minimum-number-of-lines-to-cover-points "")
-
-
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What is the highest possible answer for a set of n points?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The highest possible answer is n / 2 (rounded up). This is because you can cover at least two points with a line, and if n is odd, you need to add one extra line to cover the last point.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Suppose you have a line covering two points, how can you quickly check if a third point is also covered by that line?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Calculate the slope from the first point to the second point. If the slope from the first point to the third point is the same, then it is also covered by that line.
-</details>
diff --git a/problems/minimum-number-of-moves-to-seat-everyone/README.md b/problems/minimum-number-of-moves-to-seat-everyone/README.md
deleted file mode 100644
index 16ab9e64b..000000000
--- a/problems/minimum-number-of-moves-to-seat-everyone/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-alternating-subarray-sum "Maximum Alternating Subarray Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-colored-pieces-if-both-neighbors-are-the-same-color "Remove Colored Pieces if Both Neighbors are the Same Color")
-
-## [2037. Minimum Number of Moves to Seat Everyone (Easy)](https://leetcode.com/problems/minimum-number-of-moves-to-seat-everyone "使每位学生都有座位的最少移动次数")
-
-<p>There are <code>n</code> seats and <code>n</code> students in a room. You are given an array <code>seats</code> of length <code>n</code>, where <code>seats[i]</code> is the position of the <code>i<sup>th</sup></code> seat. You are also given the array <code>students</code> of length <code>n</code>, where <code>students[j]</code> is the position of the <code>j<sup>th</sup></code> student.</p>
-
-<p>You may perform the following move any number of times:</p>
-
-<ul>
-	<li>Increase or decrease the position of the <code>i<sup>th</sup></code> student by <code>1</code> (i.e., moving the <code>i<sup>th</sup></code> student from position&nbsp;<code>x</code>&nbsp;to <code>x + 1</code> or <code>x - 1</code>)</li>
-</ul>
-
-<p>Return <em>the <strong>minimum number of moves</strong> required to move each student to a seat</em><em> such that no two students are in the same seat.</em></p>
-
-<p>Note that there may be <strong>multiple</strong> seats or students in the <strong>same </strong>position at the beginning.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> seats = [3,1,5], students = [2,7,4]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The students are moved as follows:
-- The first student is moved from from position 2 to position 1 using 1 move.
-- The second student is moved from from position 7 to position 5 using 2 moves.
-- The third student is moved from from position 4 to position 3 using 1 move.
-In total, 1 + 2 + 1 = 4 moves were used.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> seats = [4,1,5,9], students = [1,3,2,6]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The students are moved as follows:
-- The first student is not moved.
-- The second student is moved from from position 3 to position 4 using 1 move.
-- The third student is moved from from position 2 to position 5 using 3 moves.
-- The fourth student is moved from from position 6 to position 9 using 3 moves.
-In total, 0 + 1 + 3 + 3 = 7 moves were used.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> seats = [2,2,6,6], students = [1,3,2,6]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Note that there are two seats at position 2 and two seats at position 6.
-The students are moved as follows:
-- The first student is moved from from position 1 to position 2 using 1 move.
-- The second student is moved from from position 3 to position 6 using 3 moves.
-- The third student is not moved.
-- The fourth student is not moved.
-In total, 1 + 3 + 0 + 0 = 4 moves were used.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == seats.length == students.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= seats[i], students[j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we sort the arrays to help solve the problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we greedily match each student to a seat?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The smallest positioned student will go to the smallest positioned chair, and then the next smallest positioned student will go to the next smallest positioned chair, and so on.
-</details>
diff --git a/problems/minimum-number-of-operations-to-make-array-continuous/README.md b/problems/minimum-number-of-operations-to-make-array-continuous/README.md
deleted file mode 100644
index 93bc9000d..000000000
--- a/problems/minimum-number-of-operations-to-make-array-continuous/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-earnings-from-taxi "Maximum Earnings From Taxi")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-seniors-and-juniors-to-join-the-company-ii "The Number of Seniors and Juniors to Join the Company II")
-
-## [2009. Minimum Number of Operations to Make Array Continuous (Hard)](https://leetcode.com/problems/minimum-number-of-operations-to-make-array-continuous "使数组连续的最少操作数")
-
-<p>You are given an integer array <code>nums</code>. In one operation, you can replace <strong>any</strong> element in <code>nums</code> with <strong>any</strong> integer.</p>
-
-<p><code>nums</code> is considered <strong>continuous</strong> if both of the following conditions are fulfilled:</p>
-
-<ul>
-	<li>All elements in <code>nums</code> are <strong>unique</strong>.</li>
-	<li>The difference between the <strong>maximum</strong> element and the <strong>minimum</strong> element in <code>nums</code> equals <code>nums.length - 1</code>.</li>
-</ul>
-
-<p>For example, <code>nums = [4, 2, 5, 3]</code> is <strong>continuous</strong>, but <code>nums = [1, 2, 3, 5, 6]</code> is <strong>not continuous</strong>.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of operations to make </em><code>nums</code><em> </em><strong><em>continuous</em></strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,5,3]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>&nbsp;nums is already continuous.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,5,6]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>&nbsp;One possible solution is to change the last element to 4.
-The resulting array is [1,2,3,5,4], which is continuous.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,10,100,1000]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>&nbsp;One possible solution is to:
-- Change the second element to 2.
-- Change the third element to 3.
-- Change the fourth element to 4.
-The resulting array is [1,2,3,4], which is continuous.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For every index do a binary search to get the possible right end of the window and calculate the possible answer.
-</details>
diff --git a/problems/minimum-number-of-operations-to-make-string-sorted/README.md b/problems/minimum-number-of-operations-to-make-string-sorted/README.md
deleted file mode 100644
index 60c4203fb..000000000
--- a/problems/minimum-number-of-operations-to-make-string-sorted/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-xor-for-each-query "Maximum XOR for Each Query")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-transaction-each-day "Maximum Transaction Each Day")
-
-## [1830. Minimum Number of Operations to Make String Sorted (Hard)](https://leetcode.com/problems/minimum-number-of-operations-to-make-string-sorted "使字符串有序的最少操作次数")
-
-<p>You are given a string <code>s</code> (<strong>0-indexed</strong>)​​​​​​. You are asked to perform the following operation on <code>s</code>​​​​​​ until you get a sorted string:</p>
-
-<ol>
-	<li>Find <strong>the largest index</strong> <code>i</code> such that <code>1 &lt;= i &lt; s.length</code> and <code>s[i] &lt; s[i - 1]</code>.</li>
-	<li>Find <strong>the largest index</strong> <code>j</code> such that <code>i &lt;= j &lt; s.length</code> and <code>s[k] &lt; s[i - 1]</code> for all the possible values of <code>k</code> in the range <code>[i, j]</code> inclusive.</li>
-	<li>Swap the two characters at indices <code>i - 1</code>​​​​ and <code>j</code>​​​​​.</li>
-	<li>Reverse the suffix starting at index <code>i</code>​​​​​​.</li>
-</ol>
-
-<p>Return <em>the number of operations needed to make the string sorted.</em> Since the answer can be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cba&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The simulation goes as follows:
-Operation 1: i=2, j=2. Swap s[1] and s[2] to get s=&quot;cab&quot;, then reverse the suffix starting at 2. Now, s=&quot;cab&quot;.
-Operation 2: i=1, j=2. Swap s[0] and s[2] to get s=&quot;bac&quot;, then reverse the suffix starting at 1. Now, s=&quot;bca&quot;.
-Operation 3: i=2, j=2. Swap s[1] and s[2] to get s=&quot;bac&quot;, then reverse the suffix starting at 2. Now, s=&quot;bac&quot;.
-Operation 4: i=1, j=1. Swap s[0] and s[1] to get s=&quot;abc&quot;, then reverse the suffix starting at 1. Now, s=&quot;acb&quot;.
-Operation 5: i=2, j=2. Swap s[1] and s[2] to get s=&quot;abc&quot;, then reverse the suffix starting at 2. Now, s=&quot;abc&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabaa&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The simulation goes as follows:
-Operation 1: i=3, j=4. Swap s[2] and s[4] to get s=&quot;aaaab&quot;, then reverse the substring starting at 3. Now, s=&quot;aaaba&quot;.
-Operation 2: i=4, j=4. Swap s[3] and s[4] to get s=&quot;aaaab&quot;, then reverse the substring starting at 4. Now, s=&quot;aaaab&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 3000</code></li>
-	<li><code>s</code>​​​​​​ consists only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that the operations given describe getting the previous permutation of s
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To solve this problem you need to solve every suffix separately
-</details>
diff --git a/problems/minimum-number-of-operations-to-move-all-balls-to-each-box/README.md b/problems/minimum-number-of-operations-to-move-all-balls-to-each-box/README.md
deleted file mode 100644
index 42d3cc5e1..000000000
--- a/problems/minimum-number-of-operations-to-move-all-balls-to-each-box/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../merge-strings-alternately "Merge Strings Alternately")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-score-from-performing-multiplication-operations "Maximum Score from Performing Multiplication Operations")
-
-## [1769. Minimum Number of Operations to Move All Balls to Each Box (Medium)](https://leetcode.com/problems/minimum-number-of-operations-to-move-all-balls-to-each-box "移动所有球到每个盒子所需的最小操作数")
-
-<p>You have <code>n</code> boxes. You are given a binary string <code>boxes</code> of length <code>n</code>, where <code>boxes[i]</code> is <code>&#39;0&#39;</code> if the <code>i<sup>th</sup></code> box is <strong>empty</strong>, and <code>&#39;1&#39;</code> if it contains <strong>one</strong> ball.</p>
-
-<p>In one operation, you can move <strong>one</strong> ball from a box to an adjacent box. Box <code>i</code> is adjacent to box <code>j</code> if <code>abs(i - j) == 1</code>. Note that after doing so, there may be more than one ball in some boxes.</p>
-
-<p>Return an array <code>answer</code> of size <code>n</code>, where <code>answer[i]</code> is the <strong>minimum</strong> number of operations needed to move all the balls to the <code>i<sup>th</sup></code> box.</p>
-
-<p>Each <code>answer[i]</code> is calculated considering the <strong>initial</strong> state of the boxes.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxes = &quot;110&quot;
-<strong>Output:</strong> [1,1,3]
-<strong>Explanation:</strong> The answer for each box is as follows:
-1) First box: you will have to move one ball from the second box to the first box in one operation.
-2) Second box: you will have to move one ball from the first box to the second box in one operation.
-3) Third box: you will have to move one ball from the first box to the third box in two operations, and move one ball from the second box to the third box in one operation.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxes = &quot;001011&quot;
-<strong>Output:</strong> [11,8,5,4,3,4]</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == boxes.length</code></li>
-	<li><code>1 &lt;= n &lt;= 2000</code></li>
-	<li><code>boxes[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Minimum Cost to Move Chips to The Same Position](../minimum-cost-to-move-chips-to-the-same-position) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you want to move a ball from box i to box j, you'll need abs(i-j) moves.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To move all balls to some box, you can move them one by one.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For each box i, iterate on each ball in a box j, and add abs(i-j) to answers[i].
-</details>
diff --git a/problems/minimum-number-of-operations-to-reinitialize-a-permutation/README.md b/problems/minimum-number-of-operations-to-reinitialize-a-permutation/README.md
deleted file mode 100644
index ed5e1cc09..000000000
--- a/problems/minimum-number-of-operations-to-reinitialize-a-permutation/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-different-integers-in-a-string "Number of Different Integers in a String")
-　　　　　　　　　　　　　　　　
-[Next >](../evaluate-the-bracket-pairs-of-a-string "Evaluate the Bracket Pairs of a String")
-
-## [1806. Minimum Number of Operations to Reinitialize a Permutation (Medium)](https://leetcode.com/problems/minimum-number-of-operations-to-reinitialize-a-permutation "还原排列的最少操作步数")
-
-<p>You are given an <strong>even</strong> integer <code>n</code>​​​​​​. You initially have a permutation <code>perm</code> of size <code>n</code>​​ where <code>perm[i] == i</code>​ <strong>(0-indexed)</strong>​​​​.</p>
-
-<p>In one operation, you will create a new array <code>arr</code>, and for each <code>i</code>:</p>
-
-<ul>
-	<li>If <code>i % 2 == 0</code>, then <code>arr[i] = perm[i / 2]</code>.</li>
-	<li>If <code>i % 2 == 1</code>, then <code>arr[i] = perm[n / 2 + (i - 1) / 2]</code>.</li>
-</ul>
-
-<p>You will then assign <code>arr</code>​​​​ to <code>perm</code>.</p>
-
-<p>Return <em>the minimum <strong>non-zero</strong> number of operations you need to perform on </em><code>perm</code><em> to return the permutation to its initial value.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> perm = [0,1] initially.
-After the 1<sup>st</sup> operation, perm = [0,1]
-So it takes only 1 operation.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> perm = [0,1,2,3] initially.
-After the 1<sup>st</sup> operation, perm = [0,2,1,3]
-After the 2<sup>nd</sup> operation, perm = [0,1,2,3]
-So it takes only 2 operations.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 1000</code></li>
-	<li><code>n</code>​​​​​​ is even.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-It is safe to assume the number of  operations isn't more than n
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The number is small enough to apply a brute force solution.
-</details>
diff --git a/problems/minimum-number-of-people-to-teach/README.md b/problems/minimum-number-of-people-to-teach/README.md
deleted file mode 100644
index 7dd7bea79..000000000
--- a/problems/minimum-number-of-people-to-teach/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-highest-altitude "Find the Highest Altitude")
-　　　　　　　　　　　　　　　　
-[Next >](../decode-xored-permutation "Decode XORed Permutation")
-
-## [1733. Minimum Number of People to Teach (Medium)](https://leetcode.com/problems/minimum-number-of-people-to-teach "需要教语言的最少人数")
-
-<p>On a social network consisting of <code>m</code> users and some friendships between users, two users can communicate with each other if they know a common language.</p>
-
-<p>You are given an integer <code>n</code>, an array <code>languages</code>, and an array <code>friendships</code> where:</p>
-
-<ul>
-	<li>There are <code>n</code> languages numbered <code>1</code> through <code>n</code>,</li>
-	<li><code>languages[i]</code> is the set of languages the <code>i<sup>​​​​​​th</sup></code>​​​​ user knows, and</li>
-	<li><code>friendships[i] = [u<sub>​​​​​​i</sub>​​​, v<sub>​​​​​​i</sub>]</code> denotes a friendship between the users <code>u<sup>​​​​​</sup><sub>​​​​​​i</sub></code>​​​​​ and <code>v<sub>i</sub></code>.</li>
-</ul>
-
-<p>You can choose <strong>one</strong> language and teach it to some users so that all friends can communicate with each other. Return <i data-stringify-type="italic">the</i> <i><strong>minimum</strong> </i><i data-stringify-type="italic">number of users you need to teach.</i></p>
-Note that friendships are not transitive, meaning if <code>x</code> is a friend of <code>y</code> and <code>y</code> is a friend of <code>z</code>, this doesn&#39;t guarantee that <code>x</code> is a friend of <code>z</code>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, languages = [[1],[2],[1,2]], friendships = [[1,2],[1,3],[2,3]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You can either teach user 1 the second language or user 2 the first language.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, languages = [[2],[1,3],[1,2],[3]], friendships = [[1,4],[1,2],[3,4],[2,3]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Teach the third language to users 1 and 3, yielding two users to teach.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 500</code></li>
-	<li><code>languages.length == m</code></li>
-	<li><code>1 &lt;= m &lt;= 500</code></li>
-	<li><code>1 &lt;= languages[i].length &lt;= n</code></li>
-	<li><code>1 &lt;= languages[i][j] &lt;= n</code></li>
-	<li><code>1 &lt;= u<sub>​​​​​​i</sub> &lt; v<sub>​​​​​​i</sub> &lt;= languages.length</code></li>
-	<li><code>1 &lt;= friendships.length &lt;= 500</code></li>
-	<li>All tuples <code>(u<sub>​​​​​i, </sub>v<sub>​​​​​​i</sub>)</code> are unique</li>
-	<li><code>languages[i]</code> contains only unique values</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can just use brute force and find out for each language the number of users you need to teach
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Note that a user can appear in multiple friendships but you need to teach that user only once
-</details>
diff --git a/problems/minimum-number-of-refueling-stops/README.md b/problems/minimum-number-of-refueling-stops/README.md
deleted file mode 100644
index 1cc8c8b1f..000000000
--- a/problems/minimum-number-of-refueling-stops/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../advantage-shuffle "Advantage Shuffle")
-　　　　　　　　　　　　　　　　
-[Next >](../leaf-similar-trees "Leaf-Similar Trees")
-
-## [871. Minimum Number of Refueling Stops (Hard)](https://leetcode.com/problems/minimum-number-of-refueling-stops "最低加油次数")
-
-<p>A car travels from a starting position to a destination which is <code>target</code> miles east of the starting position.</p>
-
-<p>There are gas stations along the way. The gas stations are represented as an array <code>stations</code> where <code>stations[i] = [position<sub>i</sub>, fuel<sub>i</sub>]</code> indicates that the <code>i<sup>th</sup></code> gas station is <code>position<sub>i</sub></code> miles east of the starting position and has <code>fuel<sub>i</sub></code> liters of gas.</p>
-
-<p>The car starts with an infinite tank of gas, which initially has <code>startFuel</code> liters of fuel in it. It uses one liter of gas per one mile that it drives. When the car reaches a gas station, it may stop and refuel, transferring all the gas from the station into the car.</p>
-
-<p>Return <em>the minimum number of refueling stops the car must make in order to reach its destination</em>. If it cannot reach the destination, return <code>-1</code>.</p>
-
-<p>Note that if the car reaches a gas station with <code>0</code> fuel left, the car can still refuel there. If the car reaches the destination with <code>0</code> fuel left, it is still considered to have arrived.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 1, startFuel = 1, stations = []
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> We can reach the target without refueling.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 100, startFuel = 1, stations = [[10,100]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> We can not reach the target (or even the first gas station).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 100, startFuel = 10, stations = [[10,60],[20,30],[30,30],[60,40]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We start with 10 liters of fuel.
-We drive to position 10, expending 10 liters of fuel.  We refuel from 0 liters to 60 liters of gas.
-Then, we drive from position 10 to position 60 (expending 50 liters of fuel),
-and refuel from 10 liters to 50 liters of gas.  We then drive to and reach the target.
-We made 2 refueling stops along the way, so we return 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= target, startFuel &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= stations.length &lt;= 500</code></li>
-	<li><code>0 &lt;= position<sub>i</sub> &lt;= position<sub>i+1</sub> &lt; target</code></li>
-	<li><code>1 &lt;= fuel<sub>i</sub> &lt; 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
diff --git a/problems/minimum-number-of-refueling-stops/minimum_number_of_refueling_stops.go b/problems/minimum-number-of-refueling-stops/minimum_number_of_refueling_stops.go
deleted file mode 100644
index bbc7835a4..000000000
--- a/problems/minimum-number-of-refueling-stops/minimum_number_of_refueling_stops.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem871
diff --git a/problems/minimum-number-of-refueling-stops/minimum_number_of_refueling_stops_test.go b/problems/minimum-number-of-refueling-stops/minimum_number_of_refueling_stops_test.go
deleted file mode 100644
index bbc7835a4..000000000
--- a/problems/minimum-number-of-refueling-stops/minimum_number_of_refueling_stops_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem871
diff --git a/problems/minimum-number-of-removals-to-make-mountain-array/README.md b/problems/minimum-number-of-removals-to-make-mountain-array/README.md
deleted file mode 100644
index bfc45b56b..000000000
--- a/problems/minimum-number-of-removals-to-make-mountain-array/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-front-middle-back-queue "Design Front Middle Back Queue")
-　　　　　　　　　　　　　　　　
-[Next >](../richest-customer-wealth "Richest Customer Wealth")
-
-## [1671. Minimum Number of Removals to Make Mountain Array (Hard)](https://leetcode.com/problems/minimum-number-of-removals-to-make-mountain-array "得到山形数组的最少删除次数")
-
-<p>You may recall that an array <code>arr</code> is a <strong>mountain array</strong> if and only if:</p>
-
-<ul>
-	<li><code>arr.length &gt;= 3</code></li>
-	<li>There exists some index <code>i</code> (<strong>0-indexed</strong>) with <code>0 &lt; i &lt; arr.length - 1</code> such that:
-	<ul>
-		<li><code>arr[0] &lt; arr[1] &lt; ... &lt; arr[i - 1] &lt; arr[i]</code></li>
-		<li><code>arr[i] &gt; arr[i + 1] &gt; ... &gt; arr[arr.length - 1]</code></li>
-	</ul>
-	</li>
-</ul>
-
-<p>Given an integer array <code>nums</code>​​​, return <em>the <strong>minimum</strong> number of elements to remove to make </em><code>nums<em>​​​</em></code><em> </em><em>a <strong>mountain array</strong>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The array itself is a mountain array so we do not need to remove any elements.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,1,5,6,2,3,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> One solution is to remove the elements at indices 0, 1, and 5, making the array nums = [1,5,6,3,1].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li>It is guaranteed that you can make a mountain array out of <code>nums</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think the opposite direction instead of minimum elements to remove the maximum mountain subsequence
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think of LIS it's kind of close
-</details>
diff --git a/problems/minimum-number-of-steps-to-make-two-strings-anagram/README.md b/problems/minimum-number-of-steps-to-make-two-strings-anagram/README.md
deleted file mode 100644
index 22618114e..000000000
--- a/problems/minimum-number-of-steps-to-make-two-strings-anagram/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-n-and-its-double-exist "Check If N and Its Double Exist")
-　　　　　　　　　　　　　　　　
-[Next >](../tweet-counts-per-frequency "Tweet Counts Per Frequency")
-
-## [1347. Minimum Number of Steps to Make Two Strings Anagram (Medium)](https://leetcode.com/problems/minimum-number-of-steps-to-make-two-strings-anagram "制造字母异位词的最小步骤数")
-
-<p>You are given two strings of the same length <code>s</code> and <code>t</code>. In one step you can choose <strong>any character</strong> of <code>t</code> and replace it with <strong>another character</strong>.</p>
-
-<p>Return <em>the minimum number of steps</em> to make <code>t</code> an anagram of <code>s</code>.</p>
-
-<p>An <strong>Anagram</strong> of a string is a string that contains the same characters with a different (or the same) ordering.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bab&quot;, t = &quot;aba&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Replace the first &#39;a&#39; in t with b, t = &quot;bba&quot; which is anagram of s.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;, t = &quot;practice&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Replace &#39;p&#39;, &#39;r&#39;, &#39;a&#39;, &#39;i&#39; and &#39;c&#39; from t with proper characters to make t anagram of s.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;anagram&quot;, t = &quot;mangaar&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> &quot;anagram&quot; and &quot;mangaar&quot; are anagrams. 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>s.length == t.length</code></li>
-	<li><code>s</code> and <code>t</code> consist of lowercase English letters only.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Determine if Two Strings Are Close](../determine-if-two-strings-are-close) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the frequency of characters of each string.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop over all characters if the frequency of a character in t is less than the frequency of the same character in s then add the difference between the frequencies to the answer.
-</details>
diff --git a/problems/minimum-number-of-swaps-to-make-the-binary-string-alternating/README.md b/problems/minimum-number-of-swaps-to-make-the-binary-string-alternating/README.md
deleted file mode 100644
index 51d236eaa..000000000
--- a/problems/minimum-number-of-swaps-to-make-the-binary-string-alternating/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-all-subset-xor-totals "Sum of All Subset XOR Totals")
-　　　　　　　　　　　　　　　　
-[Next >](../finding-pairs-with-a-certain-sum "Finding Pairs With a Certain Sum")
-
-## [1864. Minimum Number of Swaps to Make the Binary String Alternating (Medium)](https://leetcode.com/problems/minimum-number-of-swaps-to-make-the-binary-string-alternating "构成交替字符串需要的最小交换次数")
-
-<p>Given a binary string <code>s</code>, return <em>the <strong>minimum</strong> number of character swaps to make it <strong>alternating</strong>, or </em><code>-1</code><em> if it is impossible.</em></p>
-
-<p>The string is called <strong>alternating</strong> if no two adjacent characters are equal. For example, the strings <code>&quot;010&quot;</code> and <code>&quot;1010&quot;</code> are alternating, while the string <code>&quot;0100&quot;</code> is not.</p>
-
-<p>Any two characters may be swapped, even if they are&nbsp;<strong>not adjacent</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;111000&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Swap positions 1 and 4: &quot;1<u>1</u>10<u>0</u>0&quot; -&gt; &quot;1<u>0</u>10<u>1</u>0&quot;
-The string is now alternating.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;010&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The string is already alternating, no swaps are needed.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1110&quot;
-<strong>Output:</strong> -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think about all valid strings of length n.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to count the mismatched positions with each valid string of length n.
-</details>
diff --git a/problems/minimum-number-of-swaps-to-make-the-string-balanced/README.md b/problems/minimum-number-of-swaps-to-make-the-string-balanced/README.md
deleted file mode 100644
index 04944ffd0..000000000
--- a/problems/minimum-number-of-swaps-to-make-the-string-balanced/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-stones-to-minimize-the-total "Remove Stones to Minimize the Total")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-longest-valid-obstacle-course-at-each-position "Find the Longest Valid Obstacle Course at Each Position")
-
-## [1963. Minimum Number of Swaps to Make the String Balanced (Medium)](https://leetcode.com/problems/minimum-number-of-swaps-to-make-the-string-balanced "使字符串平衡的最小交换次数")
-
-<p>You are given a <strong>0-indexed</strong> string <code>s</code> of <strong>even</strong> length <code>n</code>. The string consists of <strong>exactly</strong> <code>n / 2</code> opening brackets <code>&#39;[&#39;</code> and <code>n / 2</code> closing brackets <code>&#39;]&#39;</code>.</p>
-
-<p>A string is called <strong>balanced</strong> if and only if:</p>
-
-<ul>
-	<li>It is the empty string, or</li>
-	<li>It can be written as <code>AB</code>, where both <code>A</code> and <code>B</code> are <strong>balanced</strong> strings, or</li>
-	<li>It can be written as <code>[C]</code>, where <code>C</code> is a <strong>balanced</strong> string.</li>
-</ul>
-
-<p>You may swap the brackets at <strong>any</strong> two indices <strong>any</strong> number of times.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of swaps to make </em><code>s</code> <em><strong>balanced</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;][][&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You can make the string balanced by swapping index 0 with index 3.
-The resulting string is &quot;[[]]&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;]]][[[&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You can do the following to make the string balanced:
-- Swap index 0 with index 4. s = &quot;[]][][&quot;.
-- Swap index 1 with index 5. s = &quot;[[][]]&quot;.
-The resulting string is &quot;[[][]]&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;[]&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The string is already balanced.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == s.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>6</sup></code></li>
-	<li><code>n</code> is even.</li>
-	<li><code>s[i]</code> is either <code>&#39;[&#39; </code>or <code>&#39;]&#39;</code>.</li>
-	<li>The number of opening brackets <code>&#39;[&#39;</code> equals <code>n / 2</code>, and the number of closing brackets <code>&#39;]&#39;</code> equals <code>n / 2</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate over the string and keep track of the number of opening and closing brackets on each step.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the number of closing brackets is ever larger, you need to make a swap.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Swap it with the opening bracket closest to the end of s.
-</details>
diff --git a/problems/minimum-number-of-taps-to-open-to-water-a-garden/README.md b/problems/minimum-number-of-taps-to-open-to-water-a-garden/README.md
deleted file mode 100644
index c44128242..000000000
--- a/problems/minimum-number-of-taps-to-open-to-water-a-garden/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-leaves-with-a-given-value "Delete Leaves With a Given Value")
-　　　　　　　　　　　　　　　　
-[Next >](../list-the-products-ordered-in-a-period "List the Products Ordered in a Period")
-
-## [1326. Minimum Number of Taps to Open to Water a Garden (Hard)](https://leetcode.com/problems/minimum-number-of-taps-to-open-to-water-a-garden "灌溉花园的最少水龙头数目")
-
-<p>There is a one-dimensional garden on the x-axis. The garden starts at the point <code>0</code> and ends at the point <code>n</code>. (i.e The length of the garden is <code>n</code>).</p>
-
-<p>There are <code>n + 1</code> taps located at points <code>[0, 1, ..., n]</code> in the garden.</p>
-
-<p>Given an integer <code>n</code> and an integer array <code>ranges</code> of length <code>n + 1</code> where <code>ranges[i]</code> (0-indexed) means the <code>i-th</code> tap can water the area <code>[i - ranges[i], i + ranges[i]]</code> if it was open.</p>
-
-<p>Return <em>the minimum number of taps</em> that should be open to water the whole garden, If the garden cannot be watered return <strong>-1</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/16/1685_example_1.png" style="width: 525px; height: 255px;" />
-<pre>
-<strong>Input:</strong> n = 5, ranges = [3,4,1,1,0,0]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The tap at point 0 can cover the interval [-3,3]
-The tap at point 1 can cover the interval [-3,5]
-The tap at point 2 can cover the interval [1,3]
-The tap at point 3 can cover the interval [2,4]
-The tap at point 4 can cover the interval [4,4]
-The tap at point 5 can cover the interval [5,5]
-Opening Only the second tap will water the whole garden [0,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, ranges = [0,0,0,0]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> Even if you activate all the four taps you cannot water the whole garden.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>ranges.length == n + 1</code></li>
-	<li><code>0 &lt;= ranges[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create intervals of the area covered by each tap, sort intervals by the left end.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We need to cover the interval [0, n]. we can start with the first interval and out of all intervals that intersect with it we choose the one that covers the farthest point to the right.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What if there is a gap between intervals that is not covered ? we should stop and return -1 as there is some interval that cannot be covered.
-</details>
diff --git a/problems/minimum-number-of-vertices-to-reach-all-nodes/README.md b/problems/minimum-number-of-vertices-to-reach-all-nodes/README.md
deleted file mode 100644
index 0732e0be0..000000000
--- a/problems/minimum-number-of-vertices-to-reach-all-nodes/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../thousand-separator "Thousand Separator")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-numbers-of-function-calls-to-make-target-array "Minimum Numbers of Function Calls to Make Target Array")
-
-## [1557. Minimum Number of Vertices to Reach All Nodes (Medium)](https://leetcode.com/problems/minimum-number-of-vertices-to-reach-all-nodes "可以到达所有点的最少点数目")
-
-<p>Given a<strong>&nbsp;directed acyclic graph</strong>,&nbsp;with&nbsp;<code>n</code>&nbsp;vertices numbered from&nbsp;<code>0</code>&nbsp;to&nbsp;<code>n-1</code>,&nbsp;and an array&nbsp;<code>edges</code>&nbsp;where&nbsp;<code>edges[i] = [from<sub>i</sub>, to<sub>i</sub>]</code>&nbsp;represents a directed edge from node&nbsp;<code>from<sub>i</sub></code>&nbsp;to node&nbsp;<code>to<sub>i</sub></code>.</p>
-
-<p>Find <em>the smallest set of vertices from which all nodes in the graph are reachable</em>. It&#39;s guaranteed that a unique solution exists.</p>
-
-<p>Notice that you can return the vertices in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/07/07/untitled22.png" style="width: 231px; height: 181px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 6, edges = [[0,1],[0,2],[2,5],[3,4],[4,2]]
-<strong>Output:</strong> [0,3]
-<b>Explanation: </b>It&#39;s not possible to reach all the nodes from a single vertex. From 0 we can reach [0,1,2,5]. From 3 we can reach [3,4,2,5]. So we output [0,3].</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/07/07/untitled.png" style="width: 201px; height: 201px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 5, edges = [[0,1],[2,1],[3,1],[1,4],[2,4]]
-<strong>Output:</strong> [0,2,3]
-<strong>Explanation: </strong>Notice that vertices 0, 3 and 2 are not reachable from any other node, so we must include them. Also any of these vertices can reach nodes 1 and 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10^5</code></li>
-	<li><code>1 &lt;= edges.length &lt;= min(10^5, n * (n - 1) / 2)</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>0 &lt;= from<sub>i,</sub>&nbsp;to<sub>i</sub> &lt; n</code></li>
-	<li>All pairs <code>(from<sub>i</sub>, to<sub>i</sub>)</code> are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A node that does not have any incoming edge can only be reached by itself.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Any other node with incoming edges can be reached from some other node.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We only have to count the number of nodes with zero incoming edges.
-</details>
diff --git a/problems/minimum-number-of-work-sessions-to-finish-the-tasks/README.md b/problems/minimum-number-of-work-sessions-to-finish-the-tasks/README.md
deleted file mode 100644
index 7062502be..000000000
--- a/problems/minimum-number-of-work-sessions-to-finish-the-tasks/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-kth-largest-integer-in-the-array "Find the Kth Largest Integer in the Array")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-unique-good-subsequences "Number of Unique Good Subsequences")
-
-## [1986. Minimum Number of Work Sessions to Finish the Tasks (Medium)](https://leetcode.com/problems/minimum-number-of-work-sessions-to-finish-the-tasks "完成任务的最少工作时间段")
-
-<p>There are <code>n</code> tasks assigned to you. The task times are represented as an integer array <code>tasks</code> of length <code>n</code>, where the <code>i<sup>th</sup></code> task takes <code>tasks[i]</code> hours to finish. A <strong>work session</strong> is when you work for <strong>at most</strong> <code>sessionTime</code> consecutive hours and then take a break.</p>
-
-<p>You should finish the given tasks in a way that satisfies the following conditions:</p>
-
-<ul>
-	<li>If you start a task in a work session, you must complete it in the <strong>same</strong> work session.</li>
-	<li>You can start a new task <strong>immediately</strong> after finishing the previous one.</li>
-	<li>You may complete the tasks in <strong>any order</strong>.</li>
-</ul>
-
-<p>Given <code>tasks</code> and <code>sessionTime</code>, return <em>the <strong>minimum</strong> number of <strong>work sessions</strong> needed to finish all the tasks following the conditions above.</em></p>
-
-<p>The tests are generated such that <code>sessionTime</code> is <strong>greater</strong> than or <strong>equal</strong> to the <strong>maximum</strong> element in <code>tasks[i]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [1,2,3], sessionTime = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You can finish the tasks in two work sessions.
-- First work session: finish the first and the second tasks in 1 + 2 = 3 hours.
-- Second work session: finish the third task in 3 hours.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [3,1,3,1,1], sessionTime = 8
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You can finish the tasks in two work sessions.
-- First work session: finish all the tasks except the last one in 3 + 1 + 3 + 1 = 8 hours.
-- Second work session: finish the last task in 1 hour.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [1,2,3,4,5], sessionTime = 15
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You can finish all the tasks in one work session.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == tasks.length</code></li>
-	<li><code>1 &lt;= n &lt;= 14</code></li>
-	<li><code>1 &lt;= tasks[i] &lt;= 10</code></li>
-	<li><code>max(tasks[i]) &lt;= sessionTime &lt;= 15</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try all possible ways of assignment.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If we can store the assignments in form of a state then we can reuse that state and solve the problem in a faster way.
-</details>
diff --git a/problems/minimum-numbers-of-function-calls-to-make-target-array/README.md b/problems/minimum-numbers-of-function-calls-to-make-target-array/README.md
deleted file mode 100644
index 78c2033c8..000000000
--- a/problems/minimum-numbers-of-function-calls-to-make-target-array/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-vertices-to-reach-all-nodes "Minimum Number of Vertices to Reach All Nodes")
-　　　　　　　　　　　　　　　　
-[Next >](../detect-cycles-in-2d-grid "Detect Cycles in 2D Grid")
-
-## [1558. Minimum Numbers of Function Calls to Make Target Array (Medium)](https://leetcode.com/problems/minimum-numbers-of-function-calls-to-make-target-array "得到目标数组的最少函数调用次数")
-
-<p>You are given an integer array <code>nums</code>. You have an integer array <code>arr</code> of the same length with all values set to <code>0</code> initially. You also have the following <code>modify</code> function:</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/10/sample_2_1887.png" style="width: 573px; height: 294px;" />
-<p>You want to use the modify function to covert <code>arr</code> to <code>nums</code> using the minimum number of calls.</p>
-
-<p>Return <em>the minimum number of function calls to make </em><code>nums</code><em> from </em><code>arr</code>.</p>
-
-<p>The test cases are generated so that the answer fits in a <strong>32-bit</strong> signed integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> Increment by 1 (second element): [0, 0] to get [0, 1] (1 operation).
-Double all the elements: [0, 1] -&gt; [0, 2] -&gt; [0, 4] (2 operations).
-Increment by 1 (both elements)  [0, 4] -&gt; [1, 4] -&gt; <strong>[1, 5]</strong> (2 operations).
-Total of operations: 1 + 2 + 2 = 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Increment by 1 (both elements) [0, 0] -&gt; [0, 1] -&gt; [1, 1] (2 operations).
-Double all the elements: [1, 1] -&gt; <strong>[2, 2]</strong> (1 operation).
-Total of operations: 2 + 1 = 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,5]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> (initial)[0,0,0] -&gt; [1,0,0] -&gt; [1,0,1] -&gt; [2,0,2] -&gt; [2,1,2] -&gt; [4,2,4] -&gt; <strong>[4,2,5]</strong>(nums).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Work backwards: try to go from nums to arr.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You should try to divide by 2 as much as possible, but you can only divide by 2 if everything is even.
-</details>
diff --git a/problems/minimum-one-bit-operations-to-make-integers-zero/README.md b/problems/minimum-one-bit-operations-to-make-integers-zero/README.md
deleted file mode 100644
index 8051fc22e..000000000
--- a/problems/minimum-one-bit-operations-to-make-integers-zero/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-visible-points "Maximum Number of Visible Points")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-two-expression-trees-are-equivalent "Check If Two Expression Trees are Equivalent")
-
-## [1611. Minimum One Bit Operations to Make Integers Zero (Hard)](https://leetcode.com/problems/minimum-one-bit-operations-to-make-integers-zero "使整数变为 0 的最少操作次数")
-
-<p>Given an integer <code>n</code>, you must transform it into <code>0</code> using the following operations any number of times:</p>
-
-<ul>
-	<li>Change the rightmost (<code>0<sup>th</sup></code>) bit in the binary representation of <code>n</code>.</li>
-	<li>Change the <code>i<sup>th</sup></code> bit in the binary representation of <code>n</code> if the <code>(i-1)<sup>th</sup></code> bit is set to <code>1</code> and the <code>(i-2)<sup>th</sup></code> through <code>0<sup>th</sup></code> bits are set to <code>0</code>.</li>
-</ul>
-
-<p>Return <em>the minimum number of operations to transform </em><code>n</code><em> into </em><code>0</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The binary representation of 3 is &quot;11&quot;.
-&quot;<u>1</u>1&quot; -&gt; &quot;<u>0</u>1&quot; with the 2<sup>nd</sup> operation since the 0<sup>th</sup> bit is 1.
-&quot;0<u>1</u>&quot; -&gt; &quot;0<u>0</u>&quot; with the 1<sup>st</sup> operation.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The binary representation of 6 is &quot;110&quot;.
-&quot;<u>1</u>10&quot; -&gt; &quot;<u>0</u>10&quot; with the 2<sup>nd</sup> operation since the 1<sup>st</sup> bit is 1 and 0<sup>th</sup> through 0<sup>th</sup> bits are 0.
-&quot;01<u>0</u>&quot; -&gt; &quot;01<u>1</u>&quot; with the 1<sup>st</sup> operation.
-&quot;0<u>1</u>1&quot; -&gt; &quot;0<u>0</u>1&quot; with the 2<sup>nd</sup> operation since the 0<sup>th</sup> bit is 1.
-&quot;00<u>1</u>&quot; -&gt; &quot;00<u>0</u>&quot; with the 1<sup>st</sup> operation.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-
-### Similar Questions
-  1. [Minimum Number of Operations to Make Array Continuous](../minimum-number-of-operations-to-make-array-continuous) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The fastest way to convert n to zero is to remove all set bits starting from the leftmost one. Try some simple examples to learn the rule of how many steps are needed to remove one set bit.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-consider n=2^k case first, then solve for all n.
-</details>
diff --git a/problems/minimum-operations-to-convert-number/README.md b/problems/minimum-operations-to-convert-number/README.md
deleted file mode 100644
index dbf649ccb..000000000
--- a/problems/minimum-operations-to-convert-number/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-minimum-and-maximum-number-of-nodes-between-critical-points "Find the Minimum and Maximum Number of Nodes Between Critical Points")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-an-original-string-exists-given-two-encoded-strings "Check if an Original String Exists Given Two Encoded Strings")
-
-## [2059. Minimum Operations to Convert Number (Medium)](https://leetcode.com/problems/minimum-operations-to-convert-number "转化数字的最小运算数")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code> containing <strong>distinct</strong> numbers, an integer <code>start</code>, and an integer <code>goal</code>. There is an integer <code>x</code> that is initially set to <code>start</code>, and you want to perform operations on <code>x</code> such that it is converted to <code>goal</code>. You can perform the following operation repeatedly on the number <code>x</code>:</p>
-
-<p>If <code>0 &lt;= x &lt;= 1000</code>, then for any index <code>i</code> in the array (<code>0 &lt;= i &lt; nums.length</code>), you can set <code>x</code> to any of the following:</p>
-
-<ul>
-	<li><code>x + nums[i]</code></li>
-	<li><code>x - nums[i]</code></li>
-	<li><code>x ^ nums[i]</code> (bitwise-XOR)</li>
-</ul>
-
-<p>Note that you can use each <code>nums[i]</code> any number of times in any order. Operations that set <code>x</code> to be out of the range <code>0 &lt;= x &lt;= 1000</code> are valid, but no more operations can be done afterward.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of operations needed to convert </em><code>x = start</code><em> into </em><code>goal</code><em>, and </em><code>-1</code><em> if it is not possible</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,4,12], start = 2, goal = 12
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We can go from 2 &rarr; 14 &rarr; 12 with the following 2 operations.
-- 2 + 12 = 14
-- 14 - 2 = 12
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,5,7], start = 0, goal = -4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We can go from 0 &rarr; 3 &rarr; -4 with the following 2 operations. 
-- 0 + 3 = 3
-- 3 - 7 = -4
-Note that the last operation sets x out of the range 0 &lt;= x &lt;= 1000, which is valid.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,8,16], start = 0, goal = 1
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There is no way to convert 0 into 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i], goal &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= start &lt;= 1000</code></li>
-	<li><code>start != goal</code></li>
-	<li>All the integers in <code>nums</code> are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Once x drops below 0 or goes above 1000, is it possible to continue performing operations on x?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can you use BFS to find the minimum operations?
-</details>
diff --git a/problems/minimum-operations-to-make-a-subsequence/README.md b/problems/minimum-operations-to-make-a-subsequence/README.md
deleted file mode 100644
index 2284fd92b..000000000
--- a/problems/minimum-operations-to-make-a-subsequence/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ways-to-split-array-into-three-subarrays "Ways to Split Array Into Three Subarrays")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-special-evenly-spaced-elements-in-array "Sum Of Special Evenly-Spaced Elements In Array")
-
-## [1713. Minimum Operations to Make a Subsequence (Hard)](https://leetcode.com/problems/minimum-operations-to-make-a-subsequence "得到子序列的最少操作次数")
-
-<p>You are given an array <code>target</code> that consists of <strong>distinct</strong> integers and another integer array <code>arr</code> that <strong>can</strong> have duplicates.</p>
-
-<p>In one operation, you can insert any integer at any position in <code>arr</code>. For example, if <code>arr = [1,4,1,2]</code>, you can add <code>3</code> in the middle and make it <code>[1,4,<u>3</u>,1,2]</code>. Note that you can insert the integer at the very beginning or end of the array.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of operations needed to make </em><code>target</code><em> a <strong>subsequence</strong> of </em><code>arr</code><em>.</em></p>
-
-<p>A <strong>subsequence</strong> of an array is a new array generated from the original array by deleting some elements (possibly none) without changing the remaining elements&#39; relative order. For example, <code>[2,7,4]</code> is a subsequence of <code>[4,<u>2</u>,3,<u>7</u>,2,1,<u>4</u>]</code> (the underlined elements), while <code>[2,4,2]</code> is not.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [5,1,3], <code>arr</code> = [9,4,2,3,4]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You can add 5 and 1 in such a way that makes <code>arr</code> = [<u>5</u>,9,4,<u>1</u>,2,3,4], then target will be a subsequence of <code>arr</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = [6,4,8,1,3,2], <code>arr</code> = [4,7,6,2,3,8,6,1]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= target.length, arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= target[i], arr[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>target</code> contains no duplicates.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The problem can be reduced to computing Longest Common Subsequence between both arrays.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Since one of the arrays has distinct elements, we can consider that these elements describe an arrangement of numbers, and we can replace each element in the other array with the index it appeared at in the first array.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Then the problem is converted to finding Longest Increasing Subsequence in the second array, which can be done in O(n log n).
-</details>
diff --git a/problems/minimum-operations-to-make-a-uni-value-grid/README.md b/problems/minimum-operations-to-make-a-uni-value-grid/README.md
deleted file mode 100644
index e0b204b83..000000000
--- a/problems/minimum-operations-to-make-a-uni-value-grid/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-out-of-three "Two Out of Three")
-　　　　　　　　　　　　　　　　
-[Next >](../stock-price-fluctuation "Stock Price Fluctuation ")
-
-## [2033. Minimum Operations to Make a Uni-Value Grid (Medium)](https://leetcode.com/problems/minimum-operations-to-make-a-uni-value-grid "获取单值网格的最小操作数")
-
-<p>You are given a 2D integer <code>grid</code> of size <code>m x n</code> and an integer <code>x</code>. In one operation, you can <strong>add</strong> <code>x</code> to or <strong>subtract</strong> <code>x</code> from any element in the <code>grid</code>.</p>
-
-<p>A <strong>uni-value grid</strong> is a grid where all the elements of it are equal.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of operations to make the grid <strong>uni-value</strong></em>. If it is not possible, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/21/gridtxt.png" style="width: 164px; height: 165px;" />
-<pre>
-<strong>Input:</strong> grid = [[2,4],[6,8]], x = 2
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> We can make every element equal to 4 by doing the following: 
-- Add x to 2 once.
-- Subtract x from 6 once.
-- Subtract x from 8 twice.
-A total of 4 operations were used.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/21/gridtxt-1.png" style="width: 164px; height: 165px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,5],[2,3]], x = 1
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> We can make every element equal to 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/21/gridtxt-2.png" style="width: 164px; height: 165px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,2],[3,4]], x = 2
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> It is impossible to make every element equal.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= m * n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= x, grid[i][j] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is it possible to make two integers a and b equal if they have different remainders dividing by x?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If it is possible, which number should you select to minimize the number of operations?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What if the elements are sorted?
-</details>
diff --git a/problems/minimum-operations-to-make-array-equal/README.md b/problems/minimum-operations-to-make-array-equal/README.md
deleted file mode 100644
index 6b184beb4..000000000
--- a/problems/minimum-operations-to-make-array-equal/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../three-consecutive-odds "Three Consecutive Odds")
-　　　　　　　　　　　　　　　　
-[Next >](../magnetic-force-between-two-balls "Magnetic Force Between Two Balls")
-
-## [1551. Minimum Operations to Make Array Equal (Medium)](https://leetcode.com/problems/minimum-operations-to-make-array-equal "使数组中所有元素相等的最小操作数")
-
-<p>You have an array <code>arr</code> of length <code>n</code> where <code>arr[i] = (2 * i) + 1</code> for all valid values of <code>i</code> (i.e.,&nbsp;<code>0 &lt;= i &lt; n</code>).</p>
-
-<p>In one operation, you can select two indices <code>x</code> and <code>y</code> where <code>0 &lt;= x, y &lt; n</code> and subtract <code>1</code> from <code>arr[x]</code> and add <code>1</code> to <code>arr[y]</code> (i.e., perform <code>arr[x] -=1 </code>and <code>arr[y] += 1</code>). The goal is to make all the elements of the array <strong>equal</strong>. It is <strong>guaranteed</strong> that all the elements of the array can be made equal using some operations.</p>
-
-<p>Given an integer <code>n</code>, the length of the array, return <em>the minimum number of operations</em> needed to make all the elements of arr equal.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> arr = [1, 3, 5]
-First operation choose x = 2 and y = 0, this leads arr to be [2, 3, 4]
-In the second operation choose x = 2 and y = 0 again, thus arr = [3, 3, 3].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6
-<strong>Output:</strong> 9
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build the array arr using the given formula, define target = sum(arr) / n
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What is the number of operations needed to convert arr so that all elements equal target ?
-</details>
diff --git a/problems/minimum-operations-to-make-the-array-alternating/README.md b/problems/minimum-operations-to-make-the-array-alternating/README.md
deleted file mode 100644
index 8b1fec07d..000000000
--- a/problems/minimum-operations-to-make-the-array-alternating/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-operations-to-obtain-zero "Count Operations to Obtain Zero")
-　　　　　　　　　　　　　　　　
-[Next >](../removing-minimum-number-of-magic-beans "Removing Minimum Number of Magic Beans")
-
-## [2170. Minimum Operations to Make the Array Alternating (Medium)](https://leetcode.com/problems/minimum-operations-to-make-the-array-alternating "使数组变成交替数组的最少操作数")
-
-<p>You are given a <strong>0-indexed</strong> array <code>nums</code> consisting of <code>n</code> positive integers.</p>
-
-<p>The array <code>nums</code> is called <strong>alternating</strong> if:</p>
-
-<ul>
-	<li><code>nums[i - 2] == nums[i]</code>, where <code>2 &lt;= i &lt;= n - 1</code>.</li>
-	<li><code>nums[i - 1] != nums[i]</code>, where <code>1 &lt;= i &lt;= n - 1</code>.</li>
-</ul>
-
-<p>In one <strong>operation</strong>, you can choose an index <code>i</code> and <strong>change</strong> <code>nums[i]</code> into <strong>any</strong> positive integer.</p>
-
-<p>Return <em>the <strong>minimum number of operations</strong> required to make the array alternating</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,3,2,4,3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-One way to make the array alternating is by converting it to [3,1,3,<u><strong>1</strong></u>,<u><strong>3</strong></u>,<u><strong>1</strong></u>].
-The number of operations required in this case is 3.
-It can be proven that it is not possible to make the array alternating in less than 3 operations. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,2,2,2]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-One way to make the array alternating is by converting it to [1,2,<u><strong>1</strong></u>,2,<u><strong>1</strong></u>].
-The number of operations required in this case is 2.
-Note that the array cannot be converted to [<u><strong>2</strong></u>,2,2,2,2] because in this case nums[0] == nums[1] which violates the conditions of an alternating array.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the frequency of each element in odd positions in the array. Do the same for elements in even positions.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To minimize the number of operations we need to maximize the number of elements we keep from the original array.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What are the possible combinations of elements we can choose from odd indices and even indices so that the number of unchanged elements is maximized?
-</details>
diff --git a/problems/minimum-operations-to-make-the-array-increasing/README.md b/problems/minimum-operations-to-make-the-array-increasing/README.md
deleted file mode 100644
index ea365b974..000000000
--- a/problems/minimum-operations-to-make-the-array-increasing/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../faulty-sensor "Faulty Sensor")
-　　　　　　　　　　　　　　　　
-[Next >](../queries-on-number-of-points-inside-a-circle "Queries on Number of Points Inside a Circle")
-
-## [1827. Minimum Operations to Make the Array Increasing (Easy)](https://leetcode.com/problems/minimum-operations-to-make-the-array-increasing "最少操作使数组递增")
-
-<p>You are given an integer array <code>nums</code> (<strong>0-indexed</strong>). In one operation, you can choose an element of the array and increment it by <code>1</code>.</p>
-
-<ul>
-	<li>For example, if <code>nums = [1,2,3]</code>, you can choose to increment <code>nums[1]</code> to make <code>nums = [1,<u><b>3</b></u>,3]</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum</strong> number of operations needed to make</em> <code>nums</code> <em><strong>strictly</strong> <strong>increasing</strong>.</em></p>
-
-<p>An array <code>nums</code> is <strong>strictly increasing</strong> if <code>nums[i] &lt; nums[i+1]</code> for all <code>0 &lt;= i &lt; nums.length - 1</code>. An array of length <code>1</code> is trivially strictly increasing.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> You can do the following operations:
-1) Increment nums[2], so nums becomes [1,1,<u><strong>2</strong></u>].
-2) Increment nums[1], so nums becomes [1,<u><strong>2</strong></u>,2].
-3) Increment nums[2], so nums becomes [1,2,<u><strong>3</strong></u>].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5,2,4,1]
-<strong>Output:</strong> 14
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [8]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-nums[i+1] must be at least equal to nums[i] + 1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think greedily. You don't have to increase nums[i+1] beyond nums[i]+1.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Iterate on i and set nums[i] = max(nums[i-1]+1, nums[i]) .
-</details>
diff --git a/problems/minimum-operations-to-make-the-array-k-increasing/README.md b/problems/minimum-operations-to-make-the-array-k-increasing/README.md
deleted file mode 100644
index 3ecfaec2b..000000000
--- a/problems/minimum-operations-to-make-the-array-k-increasing/README.md
+++ /dev/null
@@ -1,100 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-smooth-descent-periods-of-a-stock "Number of Smooth Descent Periods of a Stock")
-　　　　　　　　　　　　　　　　
-[Next >](../the-airport-with-the-most-traffic "The Airport With the Most Traffic")
-
-## [2111. Minimum Operations to Make the Array K-Increasing (Hard)](https://leetcode.com/problems/minimum-operations-to-make-the-array-k-increasing "使数组 K 递增的最少操作次数")
-
-<p>You are given a <strong>0-indexed</strong> array <code>arr</code> consisting of <code>n</code> positive integers, and a positive integer <code>k</code>.</p>
-
-<p>The array <code>arr</code> is called <strong>K-increasing</strong> if <code>arr[i-k] &lt;= arr[i]</code> holds for every index <code>i</code>, where <code>k &lt;= i &lt;= n-1</code>.</p>
-
-<ul>
-	<li>For example, <code>arr = [4, 1, 5, 2, 6, 2]</code> is K-increasing for <code>k = 2</code> because:
-	<ul>
-		<li><code>arr[0] &lt;= arr[2] (4 &lt;= 5)</code></li>
-		<li><code>arr[1] &lt;= arr[3] (1 &lt;= 2)</code></li>
-		<li><code>arr[2] &lt;= arr[4] (5 &lt;= 6)</code></li>
-		<li><code>arr[3] &lt;= arr[5] (2 &lt;= 2)</code></li>
-	</ul>
-	</li>
-	<li>However, the same <code>arr</code> is not K-increasing for <code>k = 1</code> (because <code>arr[0] &gt; arr[1]</code>) or <code>k = 3</code> (because <code>arr[0] &gt; arr[3]</code>).</li>
-</ul>
-
-<p>In one <strong>operation</strong>, you can choose an index <code>i</code> and <strong>change</strong> <code>arr[i]</code> into <strong>any</strong> positive integer.</p>
-
-<p>Return <em>the <strong>minimum number of operations</strong> required to make the array K-increasing for the given </em><code>k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [5,4,3,2,1], k = 1
-<strong>Output:</strong> 4
-<strong>Explanation:
-</strong>For k = 1, the resultant array has to be non-decreasing.
-Some of the K-increasing arrays that can be formed are [5,<u><strong>6</strong></u>,<u><strong>7</strong></u>,<u><strong>8</strong></u>,<u><strong>9</strong></u>], [<u><strong>1</strong></u>,<u><strong>1</strong></u>,<u><strong>1</strong></u>,<u><strong>1</strong></u>,1], [<u><strong>2</strong></u>,<u><strong>2</strong></u>,3,<u><strong>4</strong></u>,<u><strong>4</strong></u>]. All of them require 4 operations.
-It is suboptimal to change the array to, for example, [<u><strong>6</strong></u>,<u><strong>7</strong></u>,<u><strong>8</strong></u>,<u><strong>9</strong></u>,<u><strong>10</strong></u>] because it would take 5 operations.
-It can be shown that we cannot make the array K-increasing in less than 4 operations.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,1,5,2,6,2], k = 2
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-This is the same example as the one in the problem description.
-Here, for every index i where 2 &lt;= i &lt;= 5, arr[i-2] &lt;=<b> </b>arr[i].
-Since the given array is already K-increasing, we do not need to perform any operations.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,1,5,2,6,2], k = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-Indices 3 and 5 are the only ones not satisfying arr[i-3] &lt;= arr[i] for 3 &lt;= i &lt;= 5.
-One of the ways we can make the array K-increasing is by changing arr[3] to 4 and arr[5] to 5.
-The array will now be [4,1,5,<u><strong>4</strong></u>,6,<u><strong>5</strong></u>].
-Note that there can be other ways to make the array K-increasing, but none of them require less than 2 operations.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i], k &lt;= arr.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we divide the array into non-overlapping subsequences and simplify the problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In the final array, arr[i-k] ≤ arr[i] should hold. We can use this to divide the array into at most k non-overlapping sequences, where arr[i] will belong to the (i%k)th sequence.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Now our problem boils down to performing the minimum operations on each sequence such that it becomes non-decreasing. Our answer will be the sum of operations on each sequence.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Which indices of a sequence should we not change in order to count the minimum operations? Can finding the longest non-decreasing subsequence of the sequence help?
-</details>
diff --git a/problems/minimum-operations-to-reduce-x-to-zero/README.md b/problems/minimum-operations-to-reduce-x-to-zero/README.md
deleted file mode 100644
index a3e83af42..000000000
--- a/problems/minimum-operations-to-reduce-x-to-zero/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../determine-if-two-strings-are-close "Determine if Two Strings Are Close")
-　　　　　　　　　　　　　　　　
-[Next >](../maximize-grid-happiness "Maximize Grid Happiness")
-
-## [1658. Minimum Operations to Reduce X to Zero (Medium)](https://leetcode.com/problems/minimum-operations-to-reduce-x-to-zero "将 x 减到 0 的最小操作数")
-
-<p>You are given an integer array <code>nums</code> and an integer <code>x</code>. In one operation, you can either remove the leftmost or the rightmost element from the array <code>nums</code> and subtract its value from <code>x</code>. Note that this <strong>modifies</strong> the array for future operations.</p>
-
-<p>Return <em>the <strong>minimum number</strong> of operations to reduce </em><code>x</code> <em>to <strong>exactly</strong></em> <code>0</code> <em>if it is possible</em><em>, otherwise, return </em><code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,4,2,3], x = 5
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The optimal solution is to remove the last two elements to reduce x to zero.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,6,7,8,9], x = 4
-<strong>Output:</strong> -1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,20,1,1,3], x = 10
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The optimal solution is to remove the last three elements and the first two elements (5 operations in total) to reduce x to zero.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= x &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think in reverse; instead of finding the minimum prefix + suffix, find the maximum subarray.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Finding the maximum subarray is standard and can be done greedily.
-</details>
diff --git a/problems/minimum-operations-to-remove-adjacent-ones-in-matrix/README.md b/problems/minimum-operations-to-remove-adjacent-ones-in-matrix/README.md
deleted file mode 100644
index 1d0824208..000000000
--- a/problems/minimum-operations-to-remove-adjacent-ones-in-matrix/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../recover-the-original-array "Recover the Original Array")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-all-as-appears-before-all-bs "Check if All A's Appears Before All B's")
-
-## [2123. Minimum Operations to Remove Adjacent Ones in Matrix (Hard)](https://leetcode.com/problems/minimum-operations-to-remove-adjacent-ones-in-matrix "")
-
-
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider each cell containing a 1 as a vertex whose neighbors are the cells 4-directionally connected to it. The grid then becomes a bipartite graph.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You want to find the smallest set of vertices such that every edge in the graph has an endpoint in this set. If you remove every vertex in this set from the graph, then all the 1’s will be disconnected. Are there any well-known algorithms for finding this set?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-This set of vertices is called a minimum vertex cover. You can find the size of a minimum vertex cover by finding the size of a maximum matching (Konig’s theorem).
-</details>
-
-<details>
-<summary>Hint 4</summary>
-There are well-known algorithms such as Kuhn’s algorithm and Hopcroft-Karp-Karzanov algorithm which can find a maximum matching in a bipartite graph quickly.
-</details>
diff --git a/problems/minimum-path-cost-in-a-hidden-grid/README.md b/problems/minimum-path-cost-in-a-hidden-grid/README.md
deleted file mode 100644
index cfccec590..000000000
--- a/problems/minimum-path-cost-in-a-hidden-grid/README.md
+++ /dev/null
@@ -1,37 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ad-free-sessions "Ad-Free Sessions")
-　　　　　　　　　　　　　　　　
-[Next >](../find-interview-candidates "Find Interview Candidates")
-
-## [1810. Minimum Path Cost in a Hidden Grid (Medium)](https://leetcode.com/problems/minimum-path-cost-in-a-hidden-grid "隐藏网格下的最小消耗路径")
-
-
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The grid is at a maximum 100 x 100, so it is clever to assume that the robot's initial cell is grid[101][101]
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Run a DFS from the robot's position to make sure that you can reach the target, otherwise you should return -1.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Now that you are sure you can reach the target and that you know the grid, run Dijkstra to find the minimum cost.
-</details>
diff --git a/problems/minimum-path-sum/README.md b/problems/minimum-path-sum/README.md
deleted file mode 100644
index 082231679..000000000
--- a/problems/minimum-path-sum/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-paths-ii "Unique Paths II")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-number "Valid Number")
-
-## [64. Minimum Path Sum (Medium)](https://leetcode.com/problems/minimum-path-sum "最小路径和")
-
-<p>Given a <code>m x n</code> <code>grid</code> filled with non-negative numbers, find a path from top left to bottom right, which minimizes the sum of all numbers along its path.</p>
-
-<p><strong>Note:</strong> You can only move either down or right at any point in time.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/minpath.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,3,1],[1,5,1],[4,2,1]]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> Because the path 1 &rarr; 3 &rarr; 1 &rarr; 1 &rarr; 1 minimizes the sum.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,2,3],[4,5,6]]
-<strong>Output:</strong> 12
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Unique Paths](../unique-paths) (Medium)
-  1. [Dungeon Game](../dungeon-game) (Hard)
-  1. [Cherry Pickup](../cherry-pickup) (Hard)
diff --git a/problems/minimum-path-sum/minimum_path_sum.go b/problems/minimum-path-sum/minimum_path_sum.go
deleted file mode 100644
index be02ea9e9..000000000
--- a/problems/minimum-path-sum/minimum_path_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem64
diff --git a/problems/minimum-path-sum/minimum_path_sum_test.go b/problems/minimum-path-sum/minimum_path_sum_test.go
deleted file mode 100644
index be02ea9e9..000000000
--- a/problems/minimum-path-sum/minimum_path_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem64
diff --git a/problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits/README.md b/problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits/README.md
deleted file mode 100644
index 2bf5130bc..000000000
--- a/problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-submatrices-with-all-ones "Count Submatrices With All Ones")
-　　　　　　　　　　　　　　　　
-[Next >](../find-root-of-n-ary-tree "Find Root of N-Ary Tree")
-
-## [1505. Minimum Possible Integer After at Most K Adjacent Swaps On Digits (Hard)](https://leetcode.com/problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits "最多 K 次交换相邻数位后得到的最小整数")
-
-<p>You are given a string <code>num</code> representing <strong>the digits</strong> of a very large integer and an integer <code>k</code>. You are allowed to swap any two adjacent digits of the integer <strong>at most</strong> <code>k</code> times.</p>
-
-<p>Return <em>the minimum integer you can obtain also as a string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/17/q4_1.jpg" style="width: 500px; height: 40px;" />
-<pre>
-<strong>Input:</strong> num = &quot;4321&quot;, k = 4
-<strong>Output:</strong> &quot;1342&quot;
-<strong>Explanation:</strong> The steps to obtain the minimum integer from 4321 with 4 adjacent swaps are shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;100&quot;, k = 1
-<strong>Output:</strong> &quot;010&quot;
-<strong>Explanation:</strong> It&#39;s ok for the output to have leading zeros, but the input is guaranteed not to have any leading zeros.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;36789&quot;, k = 1000
-<strong>Output:</strong> &quot;36789&quot;
-<strong>Explanation:</strong> We can keep the number without any swaps.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>num</code> consists of only <strong>digits</strong> and does not contain <strong>leading zeros</strong>.</li>
-	<li><code>1 &lt;= k &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We want to make the smaller digits the most significant digits in the number.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each index i, check the smallest digit in a window of size k and append it to the answer. Update the indices of all digits in this range accordingly.
-</details>
diff --git a/problems/minimum-remove-to-make-valid-parentheses/README.md b/problems/minimum-remove-to-make-valid-parentheses/README.md
deleted file mode 100644
index 3dc52b55e..000000000
--- a/problems/minimum-remove-to-make-valid-parentheses/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-number-of-nice-subarrays "Count Number of Nice Subarrays")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-it-is-a-good-array "Check If It Is a Good Array")
-
-## [1249. Minimum Remove to Make Valid Parentheses (Medium)](https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses "移除无效的括号")
-
-<p>Given a string <font face="monospace">s</font> of <code>&#39;(&#39;</code> , <code>&#39;)&#39;</code> and lowercase English characters.</p>
-
-<p>Your task is to remove the minimum number of parentheses ( <code>&#39;(&#39;</code> or <code>&#39;)&#39;</code>, in any positions ) so that the resulting <em>parentheses string</em> is valid and return <strong>any</strong> valid string.</p>
-
-<p>Formally, a <em>parentheses string</em> is valid if and only if:</p>
-
-<ul>
-	<li>It is the empty string, contains only lowercase characters, or</li>
-	<li>It can be written as <code>AB</code> (<code>A</code> concatenated with <code>B</code>), where <code>A</code> and <code>B</code> are valid strings, or</li>
-	<li>It can be written as <code>(A)</code>, where <code>A</code> is a valid string.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;lee(t(c)o)de)&quot;
-<strong>Output:</strong> &quot;lee(t(c)o)de&quot;
-<strong>Explanation:</strong> &quot;lee(t(co)de)&quot; , &quot;lee(t(c)ode)&quot; would also be accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a)b(c)d&quot;
-<strong>Output:</strong> &quot;ab(c)d&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;))((&quot;
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> An empty string is also valid.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either<code>&#39;(&#39;</code> , <code>&#39;)&#39;</code>, or lowercase English letter<code>.</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Each prefix of a balanced parentheses has a number of open parentheses greater or equal than closed parentheses, similar idea with each suffix.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check the array from left to right, remove characters that do not meet the property mentioned above, same idea in backward way.
-</details>
diff --git a/problems/minimum-score-triangulation-of-polygon/README.md b/problems/minimum-score-triangulation-of-polygon/README.md
deleted file mode 100644
index 66ec63aa7..000000000
--- a/problems/minimum-score-triangulation-of-polygon/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-search-tree-to-greater-sum-tree "Binary Search Tree to Greater Sum Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../moving-stones-until-consecutive-ii "Moving Stones Until Consecutive II")
-
-## [1039. Minimum Score Triangulation of Polygon (Medium)](https://leetcode.com/problems/minimum-score-triangulation-of-polygon "多边形三角剖分的最低得分")
-
-<p>You have a convex <code>n</code>-sided polygon where each vertex has an integer value. You are given an integer array <code>values</code> where <code>values[i]</code> is the value of the <code>i<sup>th</sup></code> vertex (i.e., <strong>clockwise order</strong>).</p>
-
-<p>You will <strong>triangulate</strong> the polygon into <code>n - 2</code> triangles. For each triangle, the value of that triangle is the product of the values of its vertices, and the total score of the triangulation is the sum of these values over all <code>n - 2</code> triangles in the triangulation.</p>
-
-<p>Return <em>the smallest possible total score that you can achieve with some triangulation of the polygon</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/25/shape1.jpg" style="width: 201px; height: 133px;" />
-<pre>
-<strong>Input:</strong> values = [1,2,3]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The polygon is already triangulated, and the score of the only triangle is 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/25/shape2.jpg" style="width: 446px; height: 163px;" />
-<pre>
-<strong>Input:</strong> values = [3,7,4,5]
-<strong>Output:</strong> 144
-<strong>Explanation:</strong> There are two triangulations, with possible scores: 3*7*5 + 4*5*7 = 245, or 3*4*5 + 3*4*7 = 144.
-The minimum score is 144.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/25/shape3.jpg" style="width: 207px; height: 163px;" />
-<pre>
-<strong>Input:</strong> values = [1,3,1,4,1,5]
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> The minimum score triangulation has score 1*1*3 + 1*1*4 + 1*1*5 + 1*1*1 = 13.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == values.length</code></li>
-	<li><code>3 &lt;= n &lt;= 50</code></li>
-	<li><code>1 &lt;= values[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Without loss of generality, there is a triangle that uses adjacent vertices A[0] and A[N-1] (where N = A.length).  Depending on your choice K of it, this breaks down the triangulation into two subproblems A[1:K] and A[K+1:N-1].
-</details>
diff --git a/problems/minimum-score-triangulation-of-polygon/minimum_score_triangulation_of_polygon.go b/problems/minimum-score-triangulation-of-polygon/minimum_score_triangulation_of_polygon.go
deleted file mode 100644
index 218d93dec..000000000
--- a/problems/minimum-score-triangulation-of-polygon/minimum_score_triangulation_of_polygon.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem1039
-
-func minScoreTriangulation(A []int) int {
-	n := len(A)
-	dp := [50][50]int{}
-	for d := 2; d < n; d++ {
-		for i := 0; i+d < n; i++ {
-			k := i + d
-			dp[i][k] = 1 << 30
-			for j := i + 1; j < k; j++ {
-				dp[i][k] = min(dp[i][k], dp[i][j]+dp[j][k]+A[i]*A[j]*A[k])
-			}
-		}
-	}
-	return dp[0][n-1]
-}
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
diff --git a/problems/minimum-sideway-jumps/README.md b/problems/minimum-sideway-jumps/README.md
deleted file mode 100644
index e3df8214b..000000000
--- a/problems/minimum-sideway-jumps/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-winner-of-the-circular-game "Find the Winner of the Circular Game")
-　　　　　　　　　　　　　　　　
-[Next >](../finding-mk-average "Finding MK Average")
-
-## [1824. Minimum Sideway Jumps (Medium)](https://leetcode.com/problems/minimum-sideway-jumps "最少侧跳次数")
-
-<p>There is a <strong>3 lane road</strong> of length <code>n</code> that consists of <code>n + 1</code> <strong>points</strong> labeled from <code>0</code> to <code>n</code>. A frog <strong>starts</strong> at point <code>0</code> in the <strong>second </strong>lane<strong> </strong>and wants to jump to point <code>n</code>. However, there could be obstacles along the way.</p>
-
-<p>You are given an array <code>obstacles</code> of length <code>n + 1</code> where each <code>obstacles[i]</code> (<strong>ranging from 0 to 3</strong>) describes an obstacle on the lane <code>obstacles[i]</code> at point <code>i</code>. If <code>obstacles[i] == 0</code>, there are no obstacles at point <code>i</code>. There will be <strong>at most one</strong> obstacle in the 3 lanes at each point.</p>
-
-<ul>
-	<li>For example, if <code>obstacles[2] == 1</code>, then there is an obstacle on lane 1 at point 2.</li>
-</ul>
-
-<p>The frog can only travel from point <code>i</code> to point <code>i + 1</code> on the same lane if there is not an obstacle on the lane at point <code>i + 1</code>. To avoid obstacles, the frog can also perform a <strong>side jump</strong> to jump to <strong>another</strong> lane (even if they are not adjacent) at the <strong>same</strong> point if there is no obstacle on the new lane.</p>
-
-<ul>
-	<li>For example, the frog can jump from lane 3 at point 3 to lane 1 at point 3.</li>
-</ul>
-
-<p>Return<em> the <strong>minimum number of side jumps</strong> the frog needs to reach <strong>any lane</strong> at point n starting from lane <code>2</code> at point 0.</em></p>
-
-<p><strong>Note:</strong> There will be no obstacles on points <code>0</code> and <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/25/ic234-q3-ex1.png" style="width: 500px; height: 244px;" />
-<pre>
-<strong>Input:</strong> obstacles = [0,1,2,3,0]
-<strong>Output:</strong> 2 
-<strong>Explanation:</strong> The optimal solution is shown by the arrows above. There are 2 side jumps (red arrows).
-Note that the frog can jump over obstacles only when making side jumps (as shown at point 2).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/25/ic234-q3-ex2.png" style="width: 500px; height: 196px;" />
-<pre>
-<strong>Input:</strong> obstacles = [0,1,1,3,3,0]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no obstacles on lane 2. No side jumps are required.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/25/ic234-q3-ex3.png" style="width: 500px; height: 196px;" />
-<pre>
-<strong>Input:</strong> obstacles = [0,2,1,0,3,0]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The optimal solution is shown by the arrows above. There are 2 side jumps.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>obstacles.length == n + 1</code></li>
-	<li><code>1 &lt;= n &lt;= 5 * 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= obstacles[i] &lt;= 3</code></li>
-	<li><code>obstacles[0] == obstacles[n] == 0</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Frog Jump](../frog-jump) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-At a given point, there are only 3 possible states for where the frog can be.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Check all the ways to move from one point to the next and update the minimum side jumps for each lane.
-</details>
diff --git a/problems/minimum-size-subarray-sum/README.md b/problems/minimum-size-subarray-sum/README.md
deleted file mode 100644
index 431ecc096..000000000
--- a/problems/minimum-size-subarray-sum/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../implement-trie-prefix-tree "Implement Trie (Prefix Tree)")
-　　　　　　　　　　　　　　　　
-[Next >](../course-schedule-ii "Course Schedule II")
-
-## [209. Minimum Size Subarray Sum (Medium)](https://leetcode.com/problems/minimum-size-subarray-sum "长度最小的子数组")
-
-<p>Given an array of positive integers <code>nums</code> and a positive integer <code>target</code>, return the minimal length of a <strong>contiguous subarray</strong> <code>[nums<sub>l</sub>, nums<sub>l+1</sub>, ..., nums<sub>r-1</sub>, nums<sub>r</sub>]</code> of which the sum is greater than or equal to <code>target</code>. If there is no such subarray, return <code>0</code> instead.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 7, nums = [2,3,1,2,4,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The subarray [4,3] has the minimal length under the problem constraint.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 4, nums = [1,4,4]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 11, nums = [1,1,1,1,1,1,1,1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= target &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> If you have figured out the <code>O(n)</code> solution, try coding another solution of which the time complexity is <code>O(n log(n))</code>.
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Minimum Window Substring](../minimum-window-substring) (Hard)
-  1. [Maximum Size Subarray Sum Equals k](../maximum-size-subarray-sum-equals-k) (Medium)
-  1. [Maximum Length of Repeated Subarray](../maximum-length-of-repeated-subarray) (Medium)
diff --git a/problems/minimum-size-subarray-sum/minimum_size_subarray_sum.go b/problems/minimum-size-subarray-sum/minimum_size_subarray_sum.go
deleted file mode 100644
index 97f51037d..000000000
--- a/problems/minimum-size-subarray-sum/minimum_size_subarray_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem209
diff --git a/problems/minimum-size-subarray-sum/minimum_size_subarray_sum_test.go b/problems/minimum-size-subarray-sum/minimum_size_subarray_sum_test.go
deleted file mode 100644
index 97f51037d..000000000
--- a/problems/minimum-size-subarray-sum/minimum_size_subarray_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem209
diff --git a/problems/minimum-skips-to-arrive-at-meeting-on-time/README.md b/problems/minimum-skips-to-arrive-at-meeting-on-time/README.md
deleted file mode 100644
index 788e77637..000000000
--- a/problems/minimum-skips-to-arrive-at-meeting-on-time/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../process-tasks-using-servers "Process Tasks Using Servers")
-　　　　　　　　　　　　　　　　
-[Next >](../egg-drop-with-2-eggs-and-n-floors "Egg Drop With 2 Eggs and N Floors")
-
-## [1883. Minimum Skips to Arrive at Meeting On Time (Hard)](https://leetcode.com/problems/minimum-skips-to-arrive-at-meeting-on-time "准时抵达会议现场的最小跳过休息次数")
-
-<p>You are given an integer <code>hoursBefore</code>, the number of hours you have to travel to your meeting. To arrive at your meeting, you have to travel through <code>n</code> roads. The road lengths are given as an integer array <code>dist</code> of length <code>n</code>, where <code>dist[i]</code> describes the length of the <code>i<sup>th</sup></code> road in <strong>kilometers</strong>. In addition, you are given an integer <code>speed</code>, which is the speed (in <strong>km/h</strong>) you will travel at.</p>
-
-<p>After you travel road <code>i</code>, you must rest and wait for the <strong>next integer hour</strong> before you can begin traveling on the next road. Note that you do not have to rest after traveling the last road because you are already at the meeting.</p>
-
-<ul>
-	<li>For example, if traveling a road takes <code>1.4</code> hours, you must wait until the <code>2</code> hour mark before traveling the next road. If traveling a road takes exactly&nbsp;<code>2</code>&nbsp;hours, you do not need to wait.</li>
-</ul>
-
-<p>However, you are allowed to <strong>skip</strong> some rests to be able to arrive on time, meaning you do not need to wait for the next integer hour. Note that this means you may finish traveling future roads at different hour marks.</p>
-
-<ul>
-	<li>For example, suppose traveling the first road takes <code>1.4</code> hours and traveling the second road takes <code>0.6</code> hours. Skipping the rest after the first road will mean you finish traveling the second road right at the <code>2</code> hour mark, letting you start traveling the third road immediately.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum number of skips required</strong> to arrive at the meeting on time, or</em> <code>-1</code><em> if it is<strong> impossible</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> dist = [1,3,2], speed = 4, hoursBefore = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-Without skipping any rests, you will arrive in (1/4 + 3/4) + (3/4 + 1/4) + (2/4) = 2.5 hours.
-You can skip the first rest to arrive in ((1/4 + <u>0</u>) + (3/4 + 0)) + (2/4) = 1.5 hours.
-Note that the second rest is shortened because you finish traveling the second road at an integer hour due to skipping the first rest.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> dist = [7,3,5,5], speed = 2, hoursBefore = 10
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-Without skipping any rests, you will arrive in (7/2 + 1/2) + (3/2 + 1/2) + (5/2 + 1/2) + (5/2) = 11.5 hours.
-You can skip the first and third rest to arrive in ((7/2 + <u>0</u>) + (3/2 + 0)) + ((5/2 + <u>0</u>) + (5/2)) = 10 hours.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> dist = [7,3,5,5], speed = 1, hoursBefore = 10
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> It is impossible to arrive at the meeting on time even if you skip all the rests.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == dist.length</code></li>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= dist[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= speed &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= hoursBefore &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Minimum Speed to Arrive on Time](../minimum-speed-to-arrive-on-time) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is there something you can keep track of from one road to another?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How would knowing the start time for each state help us solve the problem?
-</details>
diff --git a/problems/minimum-space-wasted-from-packaging/README.md b/problems/minimum-space-wasted-from-packaging/README.md
deleted file mode 100644
index 5dc48480a..000000000
--- a/problems/minimum-space-wasted-from-packaging/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-flips-to-make-the-binary-string-alternating "Minimum Number of Flips to Make the Binary String Alternating")
-　　　　　　　　　　　　　　　　
-[Next >](../the-latest-login-in-2020 "The Latest Login in 2020")
-
-## [1889. Minimum Space Wasted From Packaging (Hard)](https://leetcode.com/problems/minimum-space-wasted-from-packaging "装包裹的最小浪费空间")
-
-<p>You have <code>n</code> packages that you are trying to place in boxes, <strong>one package in each box</strong>. There are <code>m</code> suppliers that each produce boxes of <strong>different sizes</strong> (with infinite supply). A package can be placed in a box if the size of the package is <strong>less than or equal to</strong> the size of the box.</p>
-
-<p>The package sizes are given as an integer array <code>packages</code>, where <code>packages[i]</code> is the <strong>size</strong> of the <code>i<sup>th</sup></code> package. The suppliers are given as a 2D integer array <code>boxes</code>, where <code>boxes[j]</code> is an array of <strong>box sizes</strong> that the <code>j<sup>th</sup></code> supplier produces.</p>
-
-<p>You want to choose a <strong>single supplier</strong> and use boxes from them such that the <strong>total wasted space </strong>is <strong>minimized</strong>. For each package in a box, we define the space <strong>wasted</strong> to be <code>size of the box - size of the package</code>. The <strong>total wasted space</strong> is the sum of the space wasted in <strong>all</strong> the boxes.</p>
-
-<ul>
-	<li>For example, if you have to fit packages with sizes <code>[2,3,5]</code> and the supplier offers boxes of sizes <code>[4,8]</code>, you can fit the packages of size-<code>2</code> and size-<code>3</code> into two boxes of size-<code>4</code> and the package with size-<code>5</code> into a box of size-<code>8</code>. This would result in a waste of <code>(4-2) + (4-3) + (8-5) = 6</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum total wasted space</strong> by choosing the box supplier <strong>optimally</strong>, or </em><code>-1</code> <i>if it is <strong>impossible</strong> to fit all the packages inside boxes. </i>Since the answer may be <strong>large</strong>, return it <strong>modulo </strong><code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> packages = [2,3,5], boxes = [[4,8],[2,8]]
-<strong>Output:</strong> 6
-<strong>Explanation</strong>: It is optimal to choose the first supplier, using two size-4 boxes and one size-8 box.
-The total waste is (4-2) + (4-3) + (8-5) = 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> packages = [2,3,5], boxes = [[1,4],[2,3],[3,4]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There is no box that the package of size 5 can fit in.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> packages = [3,5,8,10,11,12], boxes = [[12],[11,9],[10,5,14]]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> It is optimal to choose the third supplier, using two size-5 boxes, two size-10 boxes, and two size-14 boxes.
-The total waste is (5-3) + (5-5) + (10-8) + (10-10) + (14-11) + (14-12) = 9.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == packages.length</code></li>
-	<li><code>m == boxes.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= m &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= packages[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= boxes[j].length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= boxes[j][k] &lt;= 10<sup>5</sup></code></li>
-	<li><code>sum(boxes[j].length) &lt;= 10<sup>5</sup></code></li>
-	<li>The elements in <code>boxes[j]</code> are <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given a fixed size box, is there a way to quickly query which packages (i.e., count and sizes) should end up in that box size?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Do we have to order the boxes a certain way to allow us to answer the query quickly?
-</details>
diff --git a/problems/minimum-speed-to-arrive-on-time/README.md b/problems/minimum-speed-to-arrive-on-time/README.md
deleted file mode 100644
index c9ecb7bc8..000000000
--- a/problems/minimum-speed-to-arrive-on-time/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longer-contiguous-segments-of-ones-than-zeros "Longer Contiguous Segments of Ones than Zeros")
-　　　　　　　　　　　　　　　　
-[Next >](../jump-game-vii "Jump Game VII")
-
-## [1870. Minimum Speed to Arrive on Time (Medium)](https://leetcode.com/problems/minimum-speed-to-arrive-on-time "准时到达的列车最小时速")
-
-<p>You are given a floating-point number <code>hour</code>, representing the amount of time you have to reach the office. To commute to the office, you must take <code>n</code> trains in sequential order. You are also given an integer array <code>dist</code> of length <code>n</code>, where <code>dist[i]</code> describes the distance (in kilometers) of the <code>i<sup>th</sup></code> train ride.</p>
-
-<p>Each train can only depart at an integer hour, so you may need to wait in between each train ride.</p>
-
-<ul>
-	<li>For example, if the <code>1<sup>st</sup></code> train ride takes <code>1.5</code> hours, you must wait for an additional <code>0.5</code> hours before you can depart on the <code>2<sup>nd</sup></code> train ride at the 2 hour mark.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum positive integer</strong> speed <strong>(in kilometers per hour)</strong> that all the trains must travel at for you to reach the office on time, or </em><code>-1</code><em> if it is impossible to be on time</em>.</p>
-
-<p>Tests are generated such that the answer will not exceed <code>10<sup>7</sup></code> and <code>hour</code> will have <strong>at most two digits after the decimal point</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> dist = [1,3,2], hour = 6
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>At speed 1:
-- The first train ride takes 1/1 = 1 hour.
-- Since we are already at an integer hour, we depart immediately at the 1 hour mark. The second train takes 3/1 = 3 hours.
-- Since we are already at an integer hour, we depart immediately at the 4 hour mark. The third train takes 2/1 = 2 hours.
-- You will arrive at exactly the 6 hour mark.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> dist = [1,3,2], hour = 2.7
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>At speed 3:
-- The first train ride takes 1/3 = 0.33333 hours.
-- Since we are not at an integer hour, we wait until the 1 hour mark to depart. The second train ride takes 3/3 = 1 hour.
-- Since we are already at an integer hour, we depart immediately at the 2 hour mark. The third train takes 2/3 = 0.66667 hours.
-- You will arrive at the 2.66667 hour mark.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> dist = [1,3,2], hour = 1.9
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> It is impossible because the earliest the third train can depart is at the 2 hour mark.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == dist.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= dist[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= hour &lt;= 10<sup>9</sup></code></li>
-	<li>There will be at most two digits after the decimal point in <code>hour</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given the speed the trains are traveling at, can you find the total time it takes for you to arrive?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is there a cutoff where any speeds larger will always allow you to arrive on time?
-</details>
diff --git a/problems/minimum-subsequence-in-non-increasing-order/README.md b/problems/minimum-subsequence-in-non-increasing-order/README.md
deleted file mode 100644
index d9e699479..000000000
--- a/problems/minimum-subsequence-in-non-increasing-order/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reducing-dishes "Reducing Dishes")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-steps-to-reduce-a-number-in-binary-representation-to-one "Number of Steps to Reduce a Number in Binary Representation to One")
-
-## [1403. Minimum Subsequence in Non-Increasing Order (Easy)](https://leetcode.com/problems/minimum-subsequence-in-non-increasing-order "非递增顺序的最小子序列")
-
-<p>Given the array <code>nums</code>, obtain a subsequence of the array whose sum of elements is <strong>strictly greater</strong> than the sum of the non&nbsp;included elements in such subsequence.&nbsp;</p>
-
-<p>If there are multiple solutions, return the subsequence with <strong>minimum size</strong> and if there still exist multiple solutions, return the subsequence with the <strong>maximum total sum</strong> of all its elements. A subsequence of an array can be obtained by erasing some (possibly zero) elements from the array.&nbsp;</p>
-
-<p>Note that the solution with the given constraints is guaranteed to be&nbsp;<strong>unique</strong>. Also return the answer sorted in <strong>non-increasing</strong> order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,3,10,9,8]
-<strong>Output:</strong> [10,9] 
-<strong>Explanation:</strong> The subsequences [10,9] and [10,8] are minimal such that the sum of their elements is strictly greater than the sum of elements not included, however, the subsequence [10,9] has the maximum total sum of its elements.&nbsp;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,4,7,6,7]
-<strong>Output:</strong> [7,7,6] 
-<strong>Explanation:</strong> The subsequence [7,7] has the sum of its elements equal to 14 which is not strictly greater than the sum of elements not included (14 = 4 + 4 + 6). Therefore, the subsequence [7,6,7] is the minimal satisfying the conditions. Note the subsequence has to returned in non-decreasing order.  
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [6]
-<strong>Output:</strong> [6]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 500</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort elements and take each element from the largest until accomplish the conditions.
-</details>
diff --git a/problems/minimum-suffix-flips/README.md b/problems/minimum-suffix-flips/README.md
deleted file mode 100644
index 2208589ce..000000000
--- a/problems/minimum-suffix-flips/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shuffle-string "Shuffle String")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-good-leaf-nodes-pairs "Number of Good Leaf Nodes Pairs")
-
-## [1529. Minimum Suffix Flips (Medium)](https://leetcode.com/problems/minimum-suffix-flips "最少的后缀翻转次数")
-
-<p>You are given a <strong>0-indexed</strong> binary string <code>target</code> of length <code>n</code>. You have another binary string <code>s</code> of length <code>n</code> that is initially set to all zeros. You want to make <code>s</code> equal to <code>target</code>.</p>
-
-<p>In one operation, you can pick an index <code>i</code> where <code>0 &lt;= i &lt; n</code> and flip all bits in the <strong>inclusive</strong> range <code>[i, n - 1]</code>. Flip means changing <code>&#39;0&#39;</code> to <code>&#39;1&#39;</code> and <code>&#39;1&#39;</code> to <code>&#39;0&#39;</code>.</p>
-
-<p>Return <em>the minimum number of operations needed to make </em><code>s</code><em> equal to </em><code>target</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = &quot;10111&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Initially, s = &quot;00000&quot;.
-Choose index i = 2: &quot;00<u>000</u>&quot; -&gt; &quot;00<u>111</u>&quot;
-Choose index i = 0: &quot;<u>00111</u>&quot; -&gt; &quot;<u>11000</u>&quot;
-Choose index i = 1: &quot;1<u>1000</u>&quot; -&gt; &quot;1<u>0111</u>&quot;
-We need at least 3 flip operations to form target.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = &quot;101&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Initially, s = &quot;000&quot;.
-Choose index i = 0: &quot;<u>000</u>&quot; -&gt; &quot;<u>111</u>&quot;
-Choose index i = 1: &quot;1<u>11</u>&quot; -&gt; &quot;1<u>00</u>&quot;
-Choose index i = 2: &quot;10<u>0</u>&quot; -&gt; &quot;10<u>1</u>&quot;
-We need at least 3 flip operations to form target.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = &quot;00000&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> We do not need any operations since the initial s already equals target.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == target.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>target[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider a strategy where the choice of bulb with number i is increasing. In such a strategy, you no longer need to worry about bulbs that have been set to the left.
-</details>
diff --git a/problems/minimum-sum-of-four-digit-number-after-splitting-digits/README.md b/problems/minimum-sum-of-four-digit-number-after-splitting-digits/README.md
deleted file mode 100644
index a961edf68..000000000
--- a/problems/minimum-sum-of-four-digit-number-after-splitting-digits/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../order-two-columns-independently "Order Two Columns Independently")
-　　　　　　　　　　　　　　　　
-[Next >](../partition-array-according-to-given-pivot "Partition Array According to Given Pivot")
-
-## [2160. Minimum Sum of Four Digit Number After Splitting Digits (Easy)](https://leetcode.com/problems/minimum-sum-of-four-digit-number-after-splitting-digits "拆分数位后四位数字的最小和")
-
-<p>You are given a <strong>positive</strong> integer <code>num</code> consisting of exactly four digits. Split <code>num</code> into two new integers <code>new1</code> and <code>new2</code> by using the <strong>digits</strong> found in <code>num</code>. <strong>Leading zeros</strong> are allowed in <code>new1</code> and <code>new2</code>, and <strong>all</strong> the digits found in <code>num</code> must be used.</p>
-
-<ul>
-	<li>For example, given <code>num = 2932</code>, you have the following digits: two <code>2</code>&#39;s, one <code>9</code> and one <code>3</code>. Some of the possible pairs <code>[new1, new2]</code> are <code>[22, 93]</code>, <code>[23, 92]</code>, <code>[223, 9]</code> and <code>[2, 329]</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum</strong> possible sum of </em><code>new1</code><em> and </em><code>new2</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 2932
-<strong>Output:</strong> 52
-<strong>Explanation:</strong> Some possible pairs [new1, new2] are [29, 23], [223, 9], etc.
-The minimum sum can be obtained by the pair [29, 23]: 29 + 23 = 52.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 4009
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> Some possible pairs [new1, new2] are [0, 49], [490, 0], etc. 
-The minimum sum can be obtained by the pair [4, 9]: 4 + 9 = 13.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1000 &lt;= num &lt;= 9999</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Notice that the most optimal way to obtain the minimum possible sum using 4 digits is by summing up two 2-digit numbers.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can use the two smallest digits out of the four as the digits found in the tens place respectively.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Similarly, we use the final 2 larger digits as the digits found in the ones place.
-</details>
diff --git a/problems/minimum-swaps-to-arrange-a-binary-grid/README.md b/problems/minimum-swaps-to-arrange-a-binary-grid/README.md
deleted file mode 100644
index 9a67343eb..000000000
--- a/problems/minimum-swaps-to-arrange-a-binary-grid/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-winner-of-an-array-game "Find the Winner of an Array Game")
-　　　　　　　　　　　　　　　　
-[Next >](../get-the-maximum-score "Get the Maximum Score")
-
-## [1536. Minimum Swaps to Arrange a Binary Grid (Medium)](https://leetcode.com/problems/minimum-swaps-to-arrange-a-binary-grid "排布二进制网格的最少交换次数")
-
-<p>Given an <code>n x n</code> binary <code>grid</code>, in one step you can choose two <strong>adjacent rows</strong> of the grid and swap them.</p>
-
-<p>A grid is said to be <strong>valid</strong> if all the cells above the main diagonal are <strong>zeros</strong>.</p>
-
-<p>Return <em>the minimum number of steps</em> needed to make the grid valid, or <strong>-1</strong> if the grid cannot be valid.</p>
-
-<p>The main diagonal of a grid is the diagonal that starts at cell <code>(1, 1)</code> and ends at cell <code>(n, n)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/28/fw.jpg" style="width: 750px; height: 141px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,0,1],[1,1,0],[1,0,0]]
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/16/e2.jpg" style="width: 270px; height: 270px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1,1,0],[0,1,1,0],[0,1,1,0],[0,1,1,0]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> All rows are similar, swaps have no effect on the grid.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/16/e3.jpg" style="width: 200px; height: 200px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,0,0],[1,1,0],[1,1,1]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length</code> <code>== grid[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 200</code></li>
-	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each row of the grid calculate the most right 1 in the grid in the array maxRight.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To check if there exist answer, sort maxRight and check if maxRight[i] ≤ i for all possible i's.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If there exist an answer, simulate the swaps.
-</details>
diff --git a/problems/minimum-swaps-to-group-all-1s-together-ii/README.md b/problems/minimum-swaps-to-group-all-1s-together-ii/README.md
deleted file mode 100644
index f254b9dd9..000000000
--- a/problems/minimum-swaps-to-group-all-1s-together-ii/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-every-row-and-column-contains-all-numbers "Check if Every Row and Column Contains All Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../count-words-obtained-after-adding-a-letter "Count Words Obtained After Adding a Letter")
-
-## [2134. Minimum Swaps to Group All 1's Together II (Medium)](https://leetcode.com/problems/minimum-swaps-to-group-all-1s-together-ii "最少交换次数来组合所有的 1 II")
-
-<p>A <strong>swap</strong> is defined as taking two <strong>distinct</strong> positions in an array and swapping the values in them.</p>
-
-<p>A <strong>circular</strong> array is defined as an array where we consider the <strong>first</strong> element and the <strong>last</strong> element to be <strong>adjacent</strong>.</p>
-
-<p>Given a <strong>binary</strong> <strong>circular</strong> array <code>nums</code>, return <em>the minimum number of swaps required to group all </em><code>1</code><em>&#39;s present in the array together at <strong>any location</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,0,1,1,0,0]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Here are a few of the ways to group all the 1&#39;s together:
-[0,<u>0</u>,<u>1</u>,1,1,0,0] using 1 swap.
-[0,1,<u>1</u>,1,<u>0</u>,0,0] using 1 swap.
-[1,1,0,0,0,0,1] using 2 swaps (using the circular property of the array).
-There is no way to group all 1&#39;s together with 0 swaps.
-Thus, the minimum number of swaps required is 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,1,1,0,0,1,1,0]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Here are a few of the ways to group all the 1&#39;s together:
-[1,1,1,0,0,0,0,1,1] using 2 swaps (using the circular property of the array).
-[1,1,1,1,1,0,0,0,0] using 2 swaps.
-There is no way to group all 1&#39;s together with 0 or 1 swaps.
-Thus, the minimum number of swaps required is 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,0,0,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> All the 1&#39;s are already grouped together due to the circular property of the array.
-Thus, the minimum number of swaps required is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums[i]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Notice that the number of 1’s to be grouped together is fixed. It is the number of 1's the whole array has.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Call this number total. We should then check for every subarray of size total (possibly wrapped around), how many swaps are required to have the subarray be all 1’s.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The number of swaps required is the number of 0’s in the subarray.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-To eliminate the circular property of the array, we can append the original array to itself. Then, we check each subarray of length total.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-How do we avoid recounting the number of 0’s in the subarray each time? The Sliding Window technique can help.
-</details>
diff --git a/problems/minimum-swaps-to-group-all-1s-together/README.md b/problems/minimum-swaps-to-group-all-1s-together/README.md
deleted file mode 100644
index 7709f2917..000000000
--- a/problems/minimum-swaps-to-group-all-1s-together/README.md
+++ /dev/null
@@ -1,94 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-a-number-is-majority-element-in-a-sorted-array "Check If a Number Is Majority Element in a Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../analyze-user-website-visit-pattern "Analyze User Website Visit Pattern")
-
-## [1151. Minimum Swaps to Group All 1's Together (Medium)](https://leetcode.com/problems/minimum-swaps-to-group-all-1s-together "最少交换次数来组合所有的 1")
-
-<p>Given a&nbsp;binary array <code>data</code>, return&nbsp;the minimum number of swaps required to group all <code>1</code>&rsquo;s present in the array together in <strong>any place</strong> in the array.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[1,0,1,0,1]</span>
-<strong>Output: </strong><span id="example-output-1">1</span>
-<strong>Explanation: </strong>
-There are 3 ways to group all 1&#39;s together:
-[1,1,1,0,0] using 1 swap.
-[0,1,1,1,0] using 2 swaps.
-[0,0,1,1,1] using 1 swap.
-The minimum is 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">[0,0,0,1,0]</span>
-<strong>Output: </strong><span id="example-output-2">0</span>
-<strong>Explanation: </strong>
-Since there is only one 1 in the array, no swaps needed.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-3-1">[1,0,1,0,1,0,0,1,1,0,1]</span>
-<strong>Output: </strong><span id="example-output-3">3</span>
-<strong>Explanation: </strong>
-One possible solution that uses 3 swaps is [0,0,0,0,0,1,1,1,1,1,1].
-</pre>
-
-<p>&nbsp;</p>
-
-<p><span><strong>Note</strong><strong>:</strong></span></p>
-
-<ol>
-	<li><code>1 &lt;= data.length &lt;= 10^5</code></li>
-	<li><code>0 &lt;= data[i] &lt;= 1</code></li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Minimum Adjacent Swaps for K Consecutive Ones](../minimum-adjacent-swaps-for-k-consecutive-ones) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many 1's should be grouped together ? Is not a fixed number?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Yeah it's just the number of 1's the whole array has. Let's name this number as ones
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Every subarray of size of ones, needs some number of swaps to reach, Can you find the number of swaps needed to group all 1's in this subarray?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-It's the number of zeros in that subarray.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Do you need to count the number of zeros all over again for every position ?
-</details>
-
-<details>
-<summary>Hint 6</summary>
-Use Sliding Window technique.
-</details>
diff --git a/problems/minimum-swaps-to-make-sequences-increasing/README.md b/problems/minimum-swaps-to-make-sequences-increasing/README.md
deleted file mode 100644
index 81ce68ef8..000000000
--- a/problems/minimum-swaps-to-make-sequences-increasing/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../similar-rgb-color "Similar RGB Color")
-　　　　　　　　　　　　　　　　
-[Next >](../find-eventual-safe-states "Find Eventual Safe States")
-
-## [801. Minimum Swaps To Make Sequences Increasing (Hard)](https://leetcode.com/problems/minimum-swaps-to-make-sequences-increasing "使序列递增的最小交换次数")
-
-<p>You are given two integer arrays of the same length <code>nums1</code> and <code>nums2</code>. In one operation, you are allowed to swap <code>nums1[i]</code> with <code>nums2[i]</code>.</p>
-
-<ul>
-	<li>For example, if <code>nums1 = [1,2,3,<u>8</u>]</code>, and <code>nums2 = [5,6,7,<u>4</u>]</code>, you can swap the element at <code>i = 3</code> to obtain <code>nums1 = [1,2,3,4]</code> and <code>nums2 = [5,6,7,8]</code>.</li>
-</ul>
-
-<p>Return <em>the minimum number of needed operations to make </em><code>nums1</code><em> and </em><code>nums2</code><em> <strong>strictly increasing</strong></em>. The test cases are generated so that the given input always makes it possible.</p>
-
-<p>An array <code>arr</code> is <strong>strictly increasing</strong> if and only if <code>arr[0] &lt; arr[1] &lt; arr[2] &lt; ... &lt; arr[arr.length - 1]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,3,5,4], nums2 = [1,2,3,7]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 
-Swap nums1[3] and nums2[3]. Then the sequences are:
-nums1 = [1, 3, 5, 7] and nums2 = [1, 2, 3, 4]
-which are both strictly increasing.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [0,3,5,8,9], nums2 = [2,1,4,6,9]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums1.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums2.length == nums1.length</code></li>
-	<li><code>0 &lt;= nums1[i], nums2[i] &lt;= 2 * 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Minimum Operations to Make the Array K-Increasing](../minimum-operations-to-make-the-array-k-increasing) (Hard)
diff --git a/problems/minimum-swaps-to-make-sequences-increasing/minimum_swaps_to_make_sequences_increasing.go b/problems/minimum-swaps-to-make-sequences-increasing/minimum_swaps_to_make_sequences_increasing.go
deleted file mode 100644
index bf53c2335..000000000
--- a/problems/minimum-swaps-to-make-sequences-increasing/minimum_swaps_to_make_sequences_increasing.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem801
diff --git a/problems/minimum-swaps-to-make-sequences-increasing/minimum_swaps_to_make_sequences_increasing_test.go b/problems/minimum-swaps-to-make-sequences-increasing/minimum_swaps_to_make_sequences_increasing_test.go
deleted file mode 100644
index bf53c2335..000000000
--- a/problems/minimum-swaps-to-make-sequences-increasing/minimum_swaps_to_make_sequences_increasing_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem801
diff --git a/problems/minimum-swaps-to-make-strings-equal/README.md b/problems/minimum-swaps-to-make-strings-equal/README.md
deleted file mode 100644
index efa4ee8ed..000000000
--- a/problems/minimum-swaps-to-make-strings-equal/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-removal "Palindrome Removal")
-　　　　　　　　　　　　　　　　
-[Next >](../count-number-of-nice-subarrays "Count Number of Nice Subarrays")
-
-## [1247. Minimum Swaps to Make Strings Equal (Medium)](https://leetcode.com/problems/minimum-swaps-to-make-strings-equal "交换字符使得字符串相同")
-
-<p>You are given two strings <code>s1</code> and <code>s2</code> of equal length consisting of letters <code>&quot;x&quot;</code> and <code>&quot;y&quot;</code> <strong>only</strong>. Your task is to make these two strings equal to each other. You can swap any two characters that belong to <strong>different</strong> strings, which means: swap <code>s1[i]</code> and <code>s2[j]</code>.</p>
-
-<p>Return the minimum number of swaps required to make <code>s1</code> and <code>s2</code> equal, or return <code>-1</code> if it is impossible to do so.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;xx&quot;, s2 = &quot;yy&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Swap s1[0] and s2[1], s1 = &quot;yx&quot;, s2 = &quot;yx&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;xy&quot;, s2 = &quot;yx&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Swap s1[0] and s2[0], s1 = &quot;yy&quot;, s2 = &quot;xx&quot;.
-Swap s1[0] and s2[1], s1 = &quot;xy&quot;, s2 = &quot;xy&quot;.
-Note that you cannot swap s1[0] and s1[1] to make s1 equal to &quot;yx&quot;, cause we can only swap chars in different strings.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;xx&quot;, s2 = &quot;xy&quot;
-<strong>Output:</strong> -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s1.length, s2.length &lt;= 1000</code></li>
-	<li><code>s1, s2</code> only contain <code>&#39;x&#39;</code> or <code>&#39;y&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Determine if Two Strings Are Close](../determine-if-two-strings-are-close) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First, ignore all the already matched positions, they don't affect the answer at all. For the unmatched positions, there are three basic cases (already given in the examples):
-</details>
-
-<details>
-<summary>Hint 2</summary>
-("xx", "yy") => 1 swap, ("xy", "yx") => 2 swaps
-</details>
-
-<details>
-<summary>Hint 3</summary>
-So the strategy is, apply case 1 as much as possible, then apply case 2 if the last two unmatched are in this case, or fall into impossible if only one pair of unmatched left. This can be done via a simple math.
-</details>
diff --git a/problems/minimum-time-difference/README.md b/problems/minimum-time-difference/README.md
deleted file mode 100644
index de160e58a..000000000
--- a/problems/minimum-time-difference/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-bst-to-greater-tree "Convert BST to Greater Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../single-element-in-a-sorted-array "Single Element in a Sorted Array")
-
-## [539. Minimum Time Difference (Medium)](https://leetcode.com/problems/minimum-time-difference "最小时间差")
-
-Given a list of 24-hour clock time points in <strong>&quot;HH:MM&quot;</strong> format, return <em>the minimum <b>minutes</b> difference between any two time-points in the list</em>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> timePoints = ["23:59","00:00"]
-<strong>Output:</strong> 1
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> timePoints = ["00:00","23:59","00:00"]
-<strong>Output:</strong> 0
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= timePoints &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>timePoints[i]</code> is in the format <strong>&quot;HH:MM&quot;</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/minimum-time-difference/minimum_time_difference.go b/problems/minimum-time-difference/minimum_time_difference.go
deleted file mode 100644
index 83a1e5c49..000000000
--- a/problems/minimum-time-difference/minimum_time_difference.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem539
diff --git a/problems/minimum-time-difference/minimum_time_difference_test.go b/problems/minimum-time-difference/minimum_time_difference_test.go
deleted file mode 100644
index 83a1e5c49..000000000
--- a/problems/minimum-time-difference/minimum_time_difference_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem539
diff --git a/problems/minimum-time-for-k-virus-variants-to-spread/README.md b/problems/minimum-time-for-k-virus-variants-to-spread/README.md
deleted file mode 100644
index c288759ed..000000000
--- a/problems/minimum-time-for-k-virus-variants-to-spread/README.md
+++ /dev/null
@@ -1,32 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-number-of-special-subsequences "Count Number of Special Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-characters-to-make-fancy-string "Delete Characters to Make Fancy String")
-
-## [1956. Minimum Time For K Virus Variants to Spread (Hard)](https://leetcode.com/problems/minimum-time-for-k-virus-variants-to-spread "感染 K 种病毒所需的最短时间")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-n is very small, how can we use that?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What shape is the region when two viruses intersect?
-</details>
diff --git a/problems/minimum-time-to-build-blocks/README.md b/problems/minimum-time-to-build-blocks/README.md
deleted file mode 100644
index 9dc94ff90..000000000
--- a/problems/minimum-time-to-build-blocks/README.md
+++ /dev/null
@@ -1,94 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-smallest-common-element-in-all-rows "Find Smallest Common Element in All Rows")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-absolute-difference "Minimum Absolute Difference")
-
-## [1199. Minimum Time to Build Blocks (Hard)](https://leetcode.com/problems/minimum-time-to-build-blocks "建造街区的最短时间")
-
-<p>You are given a list of blocks, where <code>blocks[i] = t</code> means that the&nbsp;<code>i</code>-th block needs&nbsp;<code>t</code>&nbsp;units of time to be built. A block can only be built by exactly one worker.</p>
-
-<p>A worker can either split into two workers (number of workers increases by one) or build a block then go home. Both decisions cost some time.</p>
-
-<p>The time cost of spliting one worker into two workers is&nbsp;given as an integer <code>split</code>. Note that if two workers split at the same time, they split in parallel so the cost would be&nbsp;<code>split</code>.</p>
-
-<p>Output the minimum time needed to build all blocks.</p>
-
-<p>Initially, there is only <strong>one</strong> worker.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> blocks = [1], split = 1
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>We use 1 worker to build 1 block in 1 time unit.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> blocks = [1,2], split = 5
-<strong>Output:</strong> 7
-<strong>Explanation: </strong>We split the worker into 2 workers in 5 time units then assign each of them to a block so the cost is 5 + max(1, 2) = 7.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> blocks = [1,2,3], split = 1
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>Split 1 worker into 2, then assign the first worker to the last block and split the second worker into 2.
-Then, use the two unassigned workers to build the first two blocks.
-The cost is 1 + max(3, 1 + max(1, 2)) = 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= blocks.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= blocks[i] &lt;= 10^5</code></li>
-	<li><code>1 &lt;= split &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A greedy approach will not work as the examples show.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try all possible moves using DP.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For the DP state, dp[i][j] is the minimum time cost to build the first i blocks using j workers.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-In one step you can either assign a worker to a block or choose a number of workers to split.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-If you choose to assign a worker to a block it is always better to assign him to the block with the maximum time so we sort the array before using DP.
-</details>
-
-<details>
-<summary>Hint 6</summary>
-To optimize the solution from O(n^3) to O(n^2) notice that if you choose to split, it is always better to split all the workers you have.
-</details>
diff --git a/problems/minimum-time-to-collect-all-apples-in-a-tree/README.md b/problems/minimum-time-to-collect-all-apples-in-a-tree/README.md
deleted file mode 100644
index 7572aba8c..000000000
--- a/problems/minimum-time-to-collect-all-apples-in-a-tree/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-triplets-that-can-form-two-arrays-of-equal-xor "Count Triplets That Can Form Two Arrays of Equal XOR")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-of-cutting-a-pizza "Number of Ways of Cutting a Pizza")
-
-## [1443. Minimum Time to Collect All Apples in a Tree (Medium)](https://leetcode.com/problems/minimum-time-to-collect-all-apples-in-a-tree "收集树上所有苹果的最少时间")
-
-<p>Given an undirected tree consisting of <code>n</code> vertices numbered from <code>0</code> to <code>n-1</code>, which has some apples in their vertices. You spend 1 second to walk over one edge of the tree. <em>Return the minimum time in seconds you have to spend to collect all apples in the tree, starting at <strong>vertex 0</strong> and coming back to this vertex.</em></p>
-
-<p>The edges of the undirected tree are given in the array <code>edges</code>, where <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> means that exists an edge connecting the vertices <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code>. Additionally, there is a boolean array <code>hasApple</code>, where <code>hasApple[i] = true</code> means that vertex <code>i</code> has an apple; otherwise, it does not have any apple.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/04/23/min_time_collect_apple_1.png" style="width: 300px; height: 212px;" />
-<pre>
-<strong>Input:</strong> n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], hasApple = [false,false,true,false,true,true,false]
-<strong>Output:</strong> 8 
-<strong>Explanation:</strong> The figure above represents the given tree where red vertices have an apple. One optimal path to collect all apples is shown by the green arrows.  
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/04/23/min_time_collect_apple_2.png" style="width: 300px; height: 212px;" />
-<pre>
-<strong>Input:</strong> n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], hasApple = [false,false,true,false,false,true,false]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The figure above represents the given tree where red vertices have an apple. One optimal path to collect all apples is shown by the green arrows.  
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], hasApple = [false,false,false,false,false,false,false]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>edges.length == n - 1</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub> &lt; b<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>from<sub>i</sub> &lt; to<sub>i</sub></code></li>
-	<li><code>hasApple.length == n</code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that if a node u contains an apple then all edges in the path from the root to the node u have to be used forward and backward (2 times).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Therefore use a depth-first search (DFS) to check if an edge will be used or not.
-</details>
diff --git a/problems/minimum-time-to-make-rope-colorful/README.md b/problems/minimum-time-to-make-rope-colorful/README.md
deleted file mode 100644
index 0bbeb08a5..000000000
--- a/problems/minimum-time-to-make-rope-colorful/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers "Number of Ways Where Square of Number Is Equal to Product of Two Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-max-number-of-edges-to-keep-graph-fully-traversable "Remove Max Number of Edges to Keep Graph Fully Traversable")
-
-## [1578. Minimum Time to Make Rope Colorful (Medium)](https://leetcode.com/problems/minimum-time-to-make-rope-colorful "使绳子变成彩色的最短时间")
-
-<p>Alice has <code>n</code> balloons arranged on a rope. You are given a <strong>0-indexed</strong> string <code>colors</code> where <code>colors[i]</code> is the color of the <code>i<sup>th</sup></code> balloon.</p>
-
-<p>Alice wants the rope to be <strong>colorful</strong>. She does not want <strong>two consecutive balloons</strong> to be of the same color, so she asks Bob for help. Bob can remove some balloons from the rope to make it <strong>colorful</strong>. You are given a <strong>0-indexed</strong> integer array <code>neededTime</code> where <code>neededTime[i]</code> is the time (in seconds) that Bob needs to remove the <code>i<sup>th</sup></code> balloon from the rope.</p>
-
-<p>Return <em>the <strong>minimum time</strong> Bob needs to make the rope <strong>colorful</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/13/ballon1.jpg" style="width: 404px; height: 243px;" />
-<pre>
-<strong>Input:</strong> colors = &quot;abaac&quot;, neededTime = [1,2,3,4,5]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> In the above image, &#39;a&#39; is blue, &#39;b&#39; is red, and &#39;c&#39; is green.
-Bob can remove the blue balloon at index 2. This takes 3 seconds.
-There are no longer two consecutive balloons of the same color. Total time = 3.</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/13/balloon2.jpg" style="width: 244px; height: 243px;" />
-<pre>
-<strong>Input:</strong> colors = &quot;abc&quot;, neededTime = [1,2,3]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The rope is already colorful. Bob does not need to remove any balloons from the rope.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/13/balloon3.jpg" style="width: 404px; height: 243px;" />
-<pre>
-<strong>Input:</strong> colors = &quot;aabaa&quot;, neededTime = [1,2,3,4,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Bob will remove the ballons at indices 0 and 4. Each ballon takes 1 second to remove.
-There are no longer two consecutive balloons of the same color. Total time = 1 + 1 = 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == colors.length == neededTime.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= neededTime[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>colors</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Maintain the running sum and max value for repeated letters.
-</details>
diff --git a/problems/minimum-time-to-remove-all-cars-containing-illegal-goods/README.md b/problems/minimum-time-to-remove-all-cars-containing-illegal-goods/README.md
deleted file mode 100644
index 2d0a1ba6c..000000000
--- a/problems/minimum-time-to-remove-all-cars-containing-illegal-goods/README.md
+++ /dev/null
@@ -1,97 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-bitset "Design Bitset")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-substrings-with-equal-digit-frequency "Unique Substrings With Equal Digit Frequency")
-
-## [2167. Minimum Time to Remove All Cars Containing Illegal Goods (Hard)](https://leetcode.com/problems/minimum-time-to-remove-all-cars-containing-illegal-goods "移除所有载有违禁货物车厢所需的最少时间")
-
-<p>You are given a <strong>0-indexed</strong> binary string <code>s</code> which represents a sequence of train cars. <code>s[i] = &#39;0&#39;</code> denotes that the <code>i<sup>th</sup></code> car does <strong>not</strong> contain illegal goods and <code>s[i] = &#39;1&#39;</code> denotes that the <code>i<sup>th</sup></code> car does contain illegal goods.</p>
-
-<p>As the train conductor, you would like to get rid of all the cars containing illegal goods. You can do any of the following three operations <strong>any</strong> number of times:</p>
-
-<ol>
-	<li>Remove a train car from the <strong>left</strong> end (i.e., remove <code>s[0]</code>) which takes 1 unit of time.</li>
-	<li>Remove a train car from the <strong>right</strong> end (i.e., remove <code>s[s.length - 1]</code>) which takes 1 unit of time.</li>
-	<li>Remove a train car from <strong>anywhere</strong> in the sequence which takes 2 units of time.</li>
-</ol>
-
-<p>Return <em>the <strong>minimum</strong> time to remove all the cars containing illegal goods</em>.</p>
-
-<p>Note that an empty sequence of cars is considered to have no cars containing illegal goods.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;<strong><u>11</u></strong>00<strong><u>1</u></strong>0<strong><u>1</u></strong>&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> 
-One way to remove all the cars containing illegal goods from the sequence is to
-- remove a car from the left end 2 times. Time taken is 2 * 1 = 2.
-- remove a car from the right end. Time taken is 1.
-- remove the car containing illegal goods found in the middle. Time taken is 2.
-This obtains a total time of 2 + 1 + 2 = 5. 
-
-An alternative way is to
-- remove a car from the left end 2 times. Time taken is 2 * 1 = 2.
-- remove a car from the right end 3 times. Time taken is 3 * 1 = 3.
-This also obtains a total time of 2 + 3 = 5.
-
-5 is the minimum time taken to remove all the cars containing illegal goods. 
-There are no other ways to remove them with less time.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;00<strong><u>1</u></strong>0&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-One way to remove all the cars containing illegal goods from the sequence is to
-- remove a car from the left end 3 times. Time taken is 3 * 1 = 3.
-This obtains a total time of 3.
-
-Another way to remove all the cars containing illegal goods from the sequence is to
-- remove the car containing illegal goods found in the middle. Time taken is 2.
-This obtains a total time of 2.
-
-Another way to remove all the cars containing illegal goods from the sequence is to 
-- remove a car from the right end 2 times. Time taken is 2 * 1 = 2. 
-This obtains a total time of 2.
-
-2 is the minimum time taken to remove all the cars containing illegal goods. 
-There are no other ways to remove them with less time.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build an array withoutFirst where withoutFirst[i] stores the minimum time to remove all the cars containing illegal goods from the ‘suffix’ of the sequence starting from the ith car without using any type 1 operations.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Next, build an array onlyFirst where onlyFirst[i] stores the minimum time to remove all the cars containing illegal goods from the ‘prefix’ of the sequence ending on the ith car using only type 1 operations.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Finally, we can compare the best way to split the operations amongst these two types by finding the minimum time across all onlyFirst[i] + withoutFirst[i + 1].
-</details>
diff --git a/problems/minimum-time-to-type-word-using-special-typewriter/README.md b/problems/minimum-time-to-type-word-using-special-typewriter/README.md
deleted file mode 100644
index 3fb98afb0..000000000
--- a/problems/minimum-time-to-type-word-using-special-typewriter/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-nodes-equal-to-sum-of-descendants "Count Nodes Equal to Sum of Descendants")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-matrix-sum "Maximum Matrix Sum")
-
-## [1974. Minimum Time to Type Word Using Special Typewriter (Easy)](https://leetcode.com/problems/minimum-time-to-type-word-using-special-typewriter "使用特殊打字机键入单词的最少时间")
-
-<p>There is a special typewriter with lowercase English letters <code>&#39;a&#39;</code> to <code>&#39;z&#39;</code> arranged in a <strong>circle</strong> with a <strong>pointer</strong>. A character can <strong>only</strong> be typed if the pointer is pointing to that character. The pointer is <strong>initially</strong> pointing to the character <code>&#39;a&#39;</code>.</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/31/chart.jpg" style="width: 530px; height: 410px;" />
-<p>Each second, you may perform one of the following operations:</p>
-
-<ul>
-	<li>Move the pointer one character <strong>counterclockwise</strong> or <strong>clockwise</strong>.</li>
-	<li>Type the character the pointer is <strong>currently</strong> on.</li>
-</ul>
-
-<p>Given a string <code>word</code>, return the<strong> minimum</strong> number of seconds to type out the characters in <code>word</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;abc&quot;
-<strong>Output:</strong> 5
-<strong>Explanation: 
-</strong>The characters are printed as follows:
-- Type the character &#39;a&#39; in 1 second since the pointer is initially on &#39;a&#39;.
-- Move the pointer clockwise to &#39;b&#39; in 1 second.
-- Type the character &#39;b&#39; in 1 second.
-- Move the pointer clockwise to &#39;c&#39; in 1 second.
-- Type the character &#39;c&#39; in 1 second.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;bza&quot;
-<strong>Output:</strong> 7
-<strong>Explanation:
-</strong>The characters are printed as follows:
-- Move the pointer clockwise to &#39;b&#39; in 1 second.
-- Type the character &#39;b&#39; in 1 second.
-- Move the pointer counterclockwise to &#39;z&#39; in 2 seconds.
-- Type the character &#39;z&#39; in 1 second.
-- Move the pointer clockwise to &#39;a&#39; in 1 second.
-- Type the character &#39;a&#39; in 1 second.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;zjpc&quot;
-<strong>Output:</strong> 34
-<strong>Explanation:</strong>
-The characters are printed as follows:
-- Move the pointer counterclockwise to &#39;z&#39; in 1 second.
-- Type the character &#39;z&#39; in 1 second.
-- Move the pointer clockwise to &#39;j&#39; in 10 seconds.
-- Type the character &#39;j&#39; in 1 second.
-- Move the pointer clockwise to &#39;p&#39; in 6 seconds.
-- Type the character &#39;p&#39; in 1 second.
-- Move the pointer counterclockwise to &#39;c&#39; in 13 seconds.
-- Type the character &#39;c&#39; in 1 second.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length &lt;= 100</code></li>
-	<li><code>word</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There are only two possible directions you can go when you move to the next letter.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When moving to the next letter, you will always go in the direction that takes the least amount of time.
-</details>
diff --git a/problems/minimum-time-visiting-all-points/README.md b/problems/minimum-time-visiting-all-points/README.md
deleted file mode 100644
index 8182cda1a..000000000
--- a/problems/minimum-time-visiting-all-points/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../print-immutable-linked-list-in-reverse "Print Immutable Linked List in Reverse")
-　　　　　　　　　　　　　　　　
-[Next >](../count-servers-that-communicate "Count Servers that Communicate")
-
-## [1266. Minimum Time Visiting All Points (Easy)](https://leetcode.com/problems/minimum-time-visiting-all-points "访问所有点的最小时间")
-
-<p>On a 2D plane, there are <code>n</code> points with integer coordinates <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>. Return <em>the <strong>minimum time</strong> in seconds to visit all the points in the order given by </em><code>points</code>.</p>
-
-<p>You can move according to these rules:</p>
-
-<ul>
-	<li>In <code>1</code> second, you can either:
-	<ul>
-		<li>move vertically by one&nbsp;unit,</li>
-		<li>move horizontally by one unit, or</li>
-		<li>move diagonally <code>sqrt(2)</code> units (in other words, move one unit vertically then one unit horizontally in <code>1</code> second).</li>
-	</ul>
-	</li>
-	<li>You have to visit the points in the same order as they appear in the array.</li>
-	<li>You are allowed to pass through points that appear later in the order, but these do not count as visits.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/14/1626_example_1.PNG" style="width: 500px; height: 428px;" />
-<pre>
-<strong>Input:</strong> points = [[1,1],[3,4],[-1,0]]
-<strong>Output:</strong> 7
-<strong>Explanation: </strong>One optimal path is <strong>[1,1]</strong> -&gt; [2,2] -&gt; [3,3] -&gt; <strong>[3,4] </strong>-&gt; [2,3] -&gt; [1,2] -&gt; [0,1] -&gt; <strong>[-1,0]</strong>   
-Time from [1,1] to [3,4] = 3 seconds 
-Time from [3,4] to [-1,0] = 4 seconds
-Total time = 7 seconds</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[3,2],[-2,2]]
-<strong>Output:</strong> 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>points.length == n</code></li>
-	<li><code>1 &lt;= n&nbsp;&lt;= 100</code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>-1000&nbsp;&lt;= points[i][0], points[i][1]&nbsp;&lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-To walk from point A to point B there will be an optimal strategy to walk ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Advance in diagonal as possible then after that go in straight line.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Repeat the process until visiting all the points.
-</details>
diff --git a/problems/minimum-total-space-wasted-with-k-resizing-operations/README.md b/problems/minimum-total-space-wasted-with-k-resizing-operations/README.md
deleted file mode 100644
index 38cc07a1b..000000000
--- a/problems/minimum-total-space-wasted-with-k-resizing-operations/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-move-is-legal "Check if Move is Legal")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-product-of-the-length-of-two-palindromic-substrings "Maximum Product of the Length of Two Palindromic Substrings")
-
-## [1959. Minimum Total Space Wasted With K Resizing Operations (Medium)](https://leetcode.com/problems/minimum-total-space-wasted-with-k-resizing-operations "K 次调整数组大小浪费的最小总空间")
-
-<p>You are currently designing a dynamic array. You are given a <strong>0-indexed</strong> integer array <code>nums</code>, where <code>nums[i]</code> is the number of elements that will be in the array at time <code>i</code>. In addition, you are given an integer <code>k</code>, the <strong>maximum</strong> number of times you can <strong>resize</strong> the array (to<strong> any</strong> size).</p>
-
-<p>The size of the array at time <code>t</code>, <code>size<sub>t</sub></code>, must be at least <code>nums[t]</code> because there needs to be enough space in the array to hold all the elements. The <strong>space wasted</strong> at&nbsp;time <code>t</code> is defined as <code>size<sub>t</sub> - nums[t]</code>, and the <strong>total</strong> space wasted is the <strong>sum</strong> of the space wasted across every time <code>t</code> where <code>0 &lt;= t &lt; nums.length</code>.</p>
-
-<p>Return <em>the <strong>minimum</strong> <strong>total space wasted</strong> if you can resize the array at most</em> <code>k</code> <em>times</em>.</p>
-
-<p><strong>Note:</strong> The array can have <strong>any size</strong> at the start and does<strong> not </strong>count towards the number of resizing operations.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,20], k = 0
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> size = [20,20].
-We can set the initial size to be 20.
-The total wasted space is (20 - 10) + (20 - 20) = 10.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,20,30], k = 1
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> size = [20,20,30].
-We can set the initial size to be 20 and resize to 30 at time 2. 
-The total wasted space is (20 - 10) + (20 - 20) + (30 - 30) = 10.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,20,15,30,20], k = 2
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> size = [10,20,20,30,30].
-We can set the initial size to 10, resize to 20 at time 1, and resize to 30 at time 3.
-The total wasted space is (10 - 10) + (20 - 20) + (20 - 15) + (30 - 30) + (30 - 20) = 15.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 200</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>0 &lt;= k &lt;= nums.length - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given a range, how can you find the minimum waste if you can't perform any resize operations?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we build our solution using dynamic programming using the current index and the number of resizing operations performed as the states?
-</details>
diff --git a/problems/minimum-unique-word-abbreviation/README.md b/problems/minimum-unique-word-abbreviation/README.md
deleted file mode 100644
index a92e70f32..000000000
--- a/problems/minimum-unique-word-abbreviation/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-array-largest-sum "Split Array Largest Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../fizz-buzz "Fizz Buzz")
-
-## [411. Minimum Unique Word Abbreviation (Hard)](https://leetcode.com/problems/minimum-unique-word-abbreviation "最短独占单词缩写")
-
-<p>A string such as <code>"word"</code> contains the following abbreviations:</p>
-
-<pre>["word", "1ord", "w1rd", "wo1d", "wor1", "2rd", "w2d", "wo2", "1o1d", "1or1", "w1r1", "1o2", "2r1", "3d", "w3", "4"]
-</pre>
-
-<p>Given a target string and a set of strings in a dictionary, find an abbreviation of this target string with the <b><i>smallest possible</i></b> length such that it does not conflict with abbreviations of the strings in the dictionary. </p>
-
-<p>Each <b>number</b> or letter in the abbreviation is considered length = 1. For example, the abbreviation "a32bc" has length = 4.</p>
-
-<p><b>Note:</b><br />
-<ul>
-<li>In the case of multiple answers as shown in the second example below, you may return any one of them.</li>
-<li>Assume length of target string = <b>m</b>, and dictionary size = <b>n</b>. You may assume that <b>m &le; 21</b>, <b>n &le; 1000</b>, and <b>log<sub>2</sub>(n) + m</sup> &le; 20</b>.</li>
-</ul>
-</p>
-
-<p><b>Examples:</b><br />
-<pre>
-"apple", ["blade"] -> "a4" (because "5" or "4e" conflicts with "blade")
-
-"apple", ["plain", "amber", "blade"] -> "1p3" (other valid answers include "ap3", "a3e", "2p2", "3le", "3l1").
-</pre>
-</p>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Generalized Abbreviation](../generalized-abbreviation) (Medium)
-  1. [Valid Word Abbreviation](../valid-word-abbreviation) (Easy)
-  1. [Word Abbreviation](../word-abbreviation) (Hard)
diff --git a/problems/minimum-unique-word-abbreviation/minimum_unique_word_abbreviation.go b/problems/minimum-unique-word-abbreviation/minimum_unique_word_abbreviation.go
deleted file mode 100644
index 8468f6bda..000000000
--- a/problems/minimum-unique-word-abbreviation/minimum_unique_word_abbreviation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem411
diff --git a/problems/minimum-unique-word-abbreviation/minimum_unique_word_abbreviation_test.go b/problems/minimum-unique-word-abbreviation/minimum_unique_word_abbreviation_test.go
deleted file mode 100644
index 8468f6bda..000000000
--- a/problems/minimum-unique-word-abbreviation/minimum_unique_word_abbreviation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem411
diff --git a/problems/minimum-value-to-get-positive-step-by-step-sum/README.md b/problems/minimum-value-to-get-positive-step-by-step-sum/README.md
deleted file mode 100644
index 9d3ae86dc..000000000
--- a/problems/minimum-value-to-get-positive-step-by-step-sum/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-quiet-students-in-all-exams "Find the Quiet Students in All Exams")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k "Find the Minimum Number of Fibonacci Numbers Whose Sum Is K")
-
-## [1413. Minimum Value to Get Positive Step by Step Sum (Easy)](https://leetcode.com/problems/minimum-value-to-get-positive-step-by-step-sum "逐步求和得到正数的最小值")
-
-<p>Given an array of integers&nbsp;<code>nums</code>, you start with an initial <strong>positive</strong> value <em>startValue</em><em>.</em></p>
-
-<p>In each iteration, you calculate the step by step sum of <em>startValue</em>&nbsp;plus&nbsp;elements in <code>nums</code>&nbsp;(from left to right).</p>
-
-<p>Return the minimum <strong>positive</strong> value of&nbsp;<em>startValue</em> such that the step by step sum is never less than 1.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-3,2,-3,4,2]
-<strong>Output:</strong> 5
-<strong>Explanation: </strong>If you choose startValue = 4, in the third iteration your step by step sum is less than 1.
-<strong>step by step sum</strong>
-<strong>startValue = 4 | startValue = 5 | nums</strong>
-  (4 <strong>-3</strong> ) = 1  | (5 <strong>-3</strong> ) = 2    |  -3
-  (1 <strong>+2</strong> ) = 3  | (2 <strong>+2</strong> ) = 4    |   2
-  (3 <strong>-3</strong> ) = 0  | (4 <strong>-3</strong> ) = 1    |  -3
-  (0 <strong>+4</strong> ) = 4  | (1 <strong>+4</strong> ) = 5    |   4
-  (4 <strong>+2</strong> ) = 6  | (5 <strong>+2</strong> ) = 7    |   2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Minimum start value should be positive. 
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,-2,-3]
-<strong>Output:</strong> 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the minimum prefix sum.
-</details>
diff --git a/problems/minimum-window-subsequence/README.md b/problems/minimum-window-subsequence/README.md
deleted file mode 100644
index 21e70e9d1..000000000
--- a/problems/minimum-window-subsequence/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-atoms "Number of Atoms")
-　　　　　　　　　　　　　　　　
-[Next >](../self-dividing-numbers "Self Dividing Numbers")
-
-## [727. Minimum Window Subsequence (Hard)](https://leetcode.com/problems/minimum-window-subsequence "最小窗口子序列")
-
-<p>Given strings <code>S</code> and <code>T</code>, find the minimum (contiguous) <b>substring</b> <code>W</code> of <code>S</code>, so that <code>T</code> is a <b>subsequence</b> of <code>W</code>.</p>
-
-<p>If there is no such window in <code>S</code> that covers all characters in <code>T</code>, return the empty string <code>&quot;&quot;</code>. If there are multiple such minimum-length windows, return the one with the left-most starting index.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<b>Input:</b> 
-S = &quot;abcdebdde&quot;, T = &quot;bde&quot;
-<b>Output:</b> &quot;bcde&quot;
-<b>Explanation:</b> 
-&quot;bcde&quot; is the answer because it occurs before &quot;bdde&quot; which has the same length.
-&quot;deb&quot; is not a smaller window because the elements of T in the window must occur in order.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b></p>
-
-<ul>
-	<li>All the strings in the input will only contain lowercase letters.</li>
-	<li>The length of <code>S</code> will be in the range <code>[1, 20000]</code>.</li>
-	<li>The length of <code>T</code> will be in the range <code>[1, 100]</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Minimum Window Substring](../minimum-window-substring) (Hard)
-  1. [Longest Continuous Increasing Subsequence](../longest-continuous-increasing-subsequence) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let dp[j][e] = s be the largest index for which S[s:e+1] has T[:j] as a substring.
-</details>
diff --git a/problems/minimum-window-subsequence/minimum_window_subsequence.go b/problems/minimum-window-subsequence/minimum_window_subsequence.go
deleted file mode 100644
index 5d5b50741..000000000
--- a/problems/minimum-window-subsequence/minimum_window_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem727
diff --git a/problems/minimum-window-subsequence/minimum_window_subsequence_test.go b/problems/minimum-window-subsequence/minimum_window_subsequence_test.go
deleted file mode 100644
index 5d5b50741..000000000
--- a/problems/minimum-window-subsequence/minimum_window_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem727
diff --git a/problems/minimum-window-substring/README.md b/problems/minimum-window-substring/README.md
deleted file mode 100644
index 8fd505163..000000000
--- a/problems/minimum-window-substring/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-colors "Sort Colors")
-　　　　　　　　　　　　　　　　
-[Next >](../combinations "Combinations")
-
-## [76. Minimum Window Substring (Hard)](https://leetcode.com/problems/minimum-window-substring "最小覆盖子串")
-
-<p>Given two strings <code>s</code> and <code>t</code> of lengths <code>m</code> and <code>n</code> respectively, return <em>the <strong>minimum window substring</strong> of </em><code>s</code><em> such that every character in </em><code>t</code><em> (<strong>including duplicates</strong>) is included in the window. If there is no such substring</em><em>, return the empty string </em><code>&quot;&quot;</code><em>.</em></p>
-
-<p>The testcases will be generated such that the answer is <strong>unique</strong>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within the string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ADOBECODEBANC&quot;, t = &quot;ABC&quot;
-<strong>Output:</strong> &quot;BANC&quot;
-<strong>Explanation:</strong> The minimum window substring &quot;BANC&quot; includes &#39;A&#39;, &#39;B&#39;, and &#39;C&#39; from string t.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a&quot;, t = &quot;a&quot;
-<strong>Output:</strong> &quot;a&quot;
-<strong>Explanation:</strong> The entire string s is the minimum window.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a&quot;, t = &quot;aa&quot;
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> Both &#39;a&#39;s from t must be included in the window.
-Since the largest window of s only has one &#39;a&#39;, return empty string.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == s.length</code></li>
-	<li><code>n == t.length</code></li>
-	<li><code>1 &lt;= m, n&nbsp;&lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> and <code>t</code> consist of uppercase and lowercase English letters.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you find an algorithm that runs in <code>O(m + n)</code> time?
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Substring with Concatenation of All Words](../substring-with-concatenation-of-all-words) (Hard)
-  1. [Minimum Size Subarray Sum](../minimum-size-subarray-sum) (Medium)
-  1. [Sliding Window Maximum](../sliding-window-maximum) (Hard)
-  1. [Permutation in String](../permutation-in-string) (Medium)
-  1. [Smallest Range Covering Elements from K Lists](../smallest-range-covering-elements-from-k-lists) (Hard)
-  1. [Minimum Window Subsequence](../minimum-window-subsequence) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use two pointers to create a window of letters in <b>S</b>, which would have all the characters from <b>T</b>.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Since you have to find the minimum window in <b>S</b> which has all the characters from <b>T</b>, you need to expand and contract the window using the two pointers and keep checking the window for all the characters. This approach is also called Sliding Window Approach.
-
-<br><br>
-<pre>
-L ------------------------ R , Suppose this is the window that contains all characters of <b>T</b> 
-                          
-&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp L----------------- R , this is the contracted window. We found a smaller window that still contains all the characters in <b>T</b>
-
-When the window is no longer valid, start expanding again using the right pointer. </pre>
-</details>
diff --git a/problems/minimum-window-substring/minimum_window_substring.go b/problems/minimum-window-substring/minimum_window_substring.go
deleted file mode 100644
index 74ba15354..000000000
--- a/problems/minimum-window-substring/minimum_window_substring.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem76
diff --git a/problems/minimum-window-substring/minimum_window_substring_test.go b/problems/minimum-window-substring/minimum_window_substring_test.go
deleted file mode 100644
index 74ba15354..000000000
--- a/problems/minimum-window-substring/minimum_window_substring_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem76
diff --git a/problems/minimum-xor-sum-of-two-arrays/README.md b/problems/minimum-xor-sum-of-two-arrays/README.md
deleted file mode 100644
index e2aefc089..000000000
--- a/problems/minimum-xor-sum-of-two-arrays/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../get-biggest-three-rhombus-sums-in-a-grid "Get Biggest Three Rhombus Sums in a Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-word-equals-summation-of-two-words "Check if Word Equals Summation of Two Words")
-
-## [1879. Minimum XOR Sum of Two Arrays (Hard)](https://leetcode.com/problems/minimum-xor-sum-of-two-arrays "两个数组最小的异或值之和")
-
-<p>You are given two integer arrays <code>nums1</code> and <code>nums2</code> of length <code>n</code>.</p>
-
-<p>The <strong>XOR sum</strong> of the two integer arrays is <code>(nums1[0] XOR nums2[0]) + (nums1[1] XOR nums2[1]) + ... + (nums1[n - 1] XOR nums2[n - 1])</code> (<strong>0-indexed</strong>).</p>
-
-<ul>
-	<li>For example, the <strong>XOR sum</strong> of <code>[1,2,3]</code> and <code>[3,2,1]</code> is equal to <code>(1 XOR 3) + (2 XOR 2) + (3 XOR 1) = 2 + 0 + 2 = 4</code>.</li>
-</ul>
-
-<p>Rearrange the elements of <code>nums2</code> such that the resulting <strong>XOR sum</strong> is <b>minimized</b>.</p>
-
-<p>Return <em>the <strong>XOR sum</strong> after the rearrangement</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2], nums2 = [2,3]
-<strong>Output:</strong> 2
-<b>Explanation:</b> Rearrange <code>nums2</code> so that it becomes <code>[3,2]</code>.
-The XOR sum is (1 XOR 3) + (2 XOR 2) = 2 + 0 = 2.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,0,3], nums2 = [5,3,4]
-<strong>Output:</strong> 8
-<b>Explanation:</b> Rearrange <code>nums2</code> so that it becomes <code>[5,4,3]</code>. 
-The XOR sum is (1 XOR 5) + (0 XOR 4) + (3 XOR 3) = 4 + 4 + 0 = 8.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums1.length</code></li>
-	<li><code>n == nums2.length</code></li>
-	<li><code>1 &lt;= n &lt;= 14</code></li>
-	<li><code>0 &lt;= nums1[i], nums2[i] &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since n <= 14, we can consider every subset of nums2.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can represent every subset of nums2 using bitmasks.
-</details>
diff --git a/problems/mirror-reflection/README.md b/problems/mirror-reflection/README.md
deleted file mode 100644
index df9c98dfa..000000000
--- a/problems/mirror-reflection/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-hire-k-workers "Minimum Cost to Hire K Workers")
-　　　　　　　　　　　　　　　　
-[Next >](../buddy-strings "Buddy Strings")
-
-## [858. Mirror Reflection (Medium)](https://leetcode.com/problems/mirror-reflection "镜面反射")
-
-<p>There is a special square room with mirrors on each of the four walls. Except for the southwest corner, there are receptors on each of the remaining corners, numbered <code>0</code>, <code>1</code>, and <code>2</code>.</p>
-
-<p>The square room has walls of length <code>p</code>&nbsp;and a laser ray from the southwest corner first meets the east wall at a distance <code>q</code> from the <code>0<sup>th</sup></code> receptor.</p>
-
-<p>Given the two integers <code>p</code> and <code>q</code>, return <em>the number of the receptor that the ray meets first</em>.</p>
-
-<p>The test cases are guaranteed so that the ray will meet a receptor eventually.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/06/18/reflection.png" style="width: 218px; height: 217px;" />
-<pre>
-<strong>Input:</strong> p = 2, q = 1
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The ray meets receptor 2 the first time it gets reflected back to the left wall.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> p = 3, q = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= q &lt;= p &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
diff --git a/problems/mirror-reflection/mirror_reflection.go b/problems/mirror-reflection/mirror_reflection.go
deleted file mode 100644
index a52ba85bb..000000000
--- a/problems/mirror-reflection/mirror_reflection.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem858
diff --git a/problems/mirror-reflection/mirror_reflection_test.go b/problems/mirror-reflection/mirror_reflection_test.go
deleted file mode 100644
index a52ba85bb..000000000
--- a/problems/mirror-reflection/mirror_reflection_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem858
diff --git a/problems/missing-element-in-sorted-array/README.md b/problems/missing-element-in-sorted-array/README.md
deleted file mode 100644
index 096bf02d0..000000000
--- a/problems/missing-element-in-sorted-array/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-paths-from-source-lead-to-destination "All Paths from Source Lead to Destination")
-　　　　　　　　　　　　　　　　
-[Next >](../lexicographically-smallest-equivalent-string "Lexicographically Smallest Equivalent String")
-
-## [1060. Missing Element in Sorted Array (Medium)](https://leetcode.com/problems/missing-element-in-sorted-array "有序数组中的缺失元素")
-
-<p>Given a sorted array <code>A</code> of <strong>unique</strong> numbers, find the <code><em>K</em>-th</code> missing number starting from the leftmost number of the array.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>A = <span id="example-input-1-1">[4,7,9,10]</span>, K = 1
-<strong>Output: </strong><span id="example-output-1">5</span>
-<strong>Explanation: </strong>
-The first missing number is 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>A = <span id="example-input-2-1">[4,7,9,10]</span>, K = 3
-<strong>Output: </strong><span id="example-output-2">8</span>
-<strong>Explanation: </strong>
-The missing numbers are [5,6,8,...], hence the third missing number is 8.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong>A = <span id="example-input-3-1">[1,2,4]</span>, K = 3
-<strong>Output: </strong><span id="example-output-3">6</span>
-<strong>Explanation: </strong>
-The missing numbers are [3,5,6,7,...], hence the third missing number is 6.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= A.length &lt;= 50000</code></li>
-	<li><code>1 &lt;= A[i] &lt;= 1e7</code></li>
-	<li><code>1 &lt;= K &lt;= 1e8</code></li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First define a function f(x) that counts the number of missing elements until x.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Then use binary search with the given function f(x) to find the kth missing element.
-</details>
diff --git a/problems/missing-number-in-arithmetic-progression/README.md b/problems/missing-number-in-arithmetic-progression/README.md
deleted file mode 100644
index 26c0e9499..000000000
--- a/problems/missing-number-in-arithmetic-progression/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../airplane-seat-assignment-probability "Airplane Seat Assignment Probability")
-　　　　　　　　　　　　　　　　
-[Next >](../meeting-scheduler "Meeting Scheduler")
-
-## [1228. Missing Number In Arithmetic Progression (Easy)](https://leetcode.com/problems/missing-number-in-arithmetic-progression "等差数列中缺失的数字")
-
-<p>In some array <code>arr</code>, the values were in arithmetic progression: the values&nbsp;<code>arr[i+1] - arr[i]</code>&nbsp;are all&nbsp;equal for every&nbsp;<code>0 &lt;= i &lt; arr.length - 1</code>.</p>
-
-<p>Then, a value from <code>arr</code>&nbsp;was removed that <strong>was&nbsp;not the first or last value in the array</strong>.</p>
-
-<p>Return the removed value.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [5,7,11,13]
-<strong>Output:</strong> 9
-<strong>Explanation: </strong>The previous array was [5,7,<strong>9</strong>,11,13].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [15,13,12]
-<strong>Output:</strong> 14
-<strong>Explanation: </strong>The previous array was [15,<strong>14</strong>,13,12].</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10^5</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Assume the sequence is increasing, what if we find the largest consecutive difference?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is the missing element in the middle of the segment with the largest consecutive difference?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For decreasing sequences, just reverse the array and do a similar process.
-</details>
diff --git a/problems/missing-number/README.md b/problems/missing-number/README.md
deleted file mode 100644
index 6c6174e60..000000000
--- a/problems/missing-number/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-permutation-ii "Palindrome Permutation II")
-　　　　　　　　　　　　　　　　
-[Next >](../alien-dictionary "Alien Dictionary")
-
-## [268. Missing Number (Easy)](https://leetcode.com/problems/missing-number "丢失的数字")
-
-<p>Given an array <code>nums</code> containing <code>n</code> distinct numbers in the range <code>[0, n]</code>, return <em>the only number in the range that is missing from the array.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,0,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> n = 3 since there are 3 numbers, so all numbers are in the range [0,3]. 2 is the missing number in the range since it does not appear in nums.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> n = 2 since there are 2 numbers, so all numbers are in the range [0,2]. 2 is the missing number in the range since it does not appear in nums.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,6,4,2,3,5,7,0,1]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> n = 9 since there are 9 numbers, so all numbers are in the range [0,9]. 8 is the missing number in the range since it does not appear in nums.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= n</code></li>
-	<li>All the numbers of <code>nums</code> are <strong>unique</strong>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you implement a solution using only <code>O(1)</code> extra space complexity and <code>O(n)</code> runtime complexity?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [First Missing Positive](../first-missing-positive) (Hard)
-  1. [Single Number](../single-number) (Easy)
-  1. [Find the Duplicate Number](../find-the-duplicate-number) (Medium)
-  1. [Couples Holding Hands](../couples-holding-hands) (Hard)
-  1. [Find Unique Binary String](../find-unique-binary-string) (Medium)
diff --git a/problems/missing-number/missing_number.go b/problems/missing-number/missing_number.go
deleted file mode 100644
index 0f5d52ae5..000000000
--- a/problems/missing-number/missing_number.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package problem268
-
-func missingNumber(nums []int) int {
-	sum, n := 0, len(nums)
-	for _, v := range nums {
-		sum += v
-	}
-	return (n+1)*n/2 - sum
-}
diff --git a/problems/missing-number/missing_number_test.go b/problems/missing-number/missing_number_test.go
deleted file mode 100644
index 267263af2..000000000
--- a/problems/missing-number/missing_number_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem268
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestMissingNumber(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 0, 1},
-			want: 2,
-		},
-		{
-			in:   []int{0, 1, 2, 4, 5, 6},
-			want: 3,
-		},
-		{
-			in:   []int{9, 6, 4, 2, 3, 5, 7, 0, 1},
-			want: 8,
-		},
-	}
-	for _, tt := range tests {
-		got := missingNumber(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/missing-ranges/README.md b/problems/missing-ranges/README.md
deleted file mode 100644
index 0b127da34..000000000
--- a/problems/missing-ranges/README.md
+++ /dev/null
@@ -1,27 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-peak-element "Find Peak Element")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-gap "Maximum Gap")
-
-## [163. Missing Ranges (Easy)](https://leetcode.com/problems/missing-ranges "缺失的区间")
-
-<p>Given a sorted integer array <strong><em>nums</em></strong>, where the range of elements are in the <strong>inclusive range</strong><b><strong> </strong>[<i>lower</i>, <i>upper</i>]</b>, return its missing ranges.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> <strong><em>nums</em></strong> = <code>[0, 1, 3, 50, 75]</code>, <strong><i>lower</i></strong> = 0 and <strong><i>upper</i></strong> = 99,
-<strong>Output:</strong> <code>[&quot;2&quot;, &quot;4-&gt;49&quot;, &quot;51-&gt;74&quot;, &quot;76-&gt;99&quot;]</code>
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Summary Ranges](../summary-ranges) (Easy)
diff --git a/problems/missing-ranges/missing_ranges.go b/problems/missing-ranges/missing_ranges.go
deleted file mode 100644
index ac83d2393..000000000
--- a/problems/missing-ranges/missing_ranges.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem163
diff --git a/problems/missing-ranges/missing_ranges_test.go b/problems/missing-ranges/missing_ranges_test.go
deleted file mode 100644
index ac83d2393..000000000
--- a/problems/missing-ranges/missing_ranges_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem163
diff --git a/problems/monotone-increasing-digits/README.md b/problems/monotone-increasing-digits/README.md
deleted file mode 100644
index dca596465..000000000
--- a/problems/monotone-increasing-digits/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sentence-similarity-ii "Sentence Similarity II")
-　　　　　　　　　　　　　　　　
-[Next >](../daily-temperatures "Daily Temperatures")
-
-## [738. Monotone Increasing Digits (Medium)](https://leetcode.com/problems/monotone-increasing-digits "单调递增的数字")
-
-<p>An integer has <strong>monotone increasing digits</strong> if and only if each pair of adjacent digits <code>x</code> and <code>y</code> satisfy <code>x &lt;= y</code>.</p>
-
-<p>Given an integer <code>n</code>, return <em>the largest number that is less than or equal to </em><code>n</code><em> with <strong>monotone increasing digits</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 9
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1234
-<strong>Output:</strong> 1234
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 332
-<strong>Output:</strong> 299
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Remove K Digits](../remove-k-digits) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build the answer digit by digit, adding the largest possible one that would make the number still less than or equal to N.
-</details>
diff --git a/problems/monotone-increasing-digits/monotone_increasing_digits.go b/problems/monotone-increasing-digits/monotone_increasing_digits.go
deleted file mode 100644
index 5083ea4d6..000000000
--- a/problems/monotone-increasing-digits/monotone_increasing_digits.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem738
diff --git a/problems/monotone-increasing-digits/monotone_increasing_digits_test.go b/problems/monotone-increasing-digits/monotone_increasing_digits_test.go
deleted file mode 100644
index 5083ea4d6..000000000
--- a/problems/monotone-increasing-digits/monotone_increasing_digits_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem738
diff --git a/problems/monotonic-array/README.md b/problems/monotonic-array/README.md
deleted file mode 100644
index 4c0ca297e..000000000
--- a/problems/monotonic-array/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-frequency-stack "Maximum Frequency Stack")
-　　　　　　　　　　　　　　　　
-[Next >](../increasing-order-search-tree "Increasing Order Search Tree")
-
-## [896. Monotonic Array (Easy)](https://leetcode.com/problems/monotonic-array "单调数列")
-
-<p>An array is <strong>monotonic</strong> if it is either monotone increasing or monotone decreasing.</p>
-
-<p>An array <code>nums</code> is monotone increasing if for all <code>i &lt;= j</code>, <code>nums[i] &lt;= nums[j]</code>. An array <code>nums</code> is monotone decreasing if for all <code>i &lt;= j</code>, <code>nums[i] &gt;= nums[j]</code>.</p>
-
-<p>Given an integer array <code>nums</code>, return <code>true</code><em> if the given array is monotonic, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,2,3]
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [6,5,4,4]
-<strong>Output:</strong> true
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [1,3,2]
-<strong>Output:</strong> false
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,4,5]
-<strong>Output:</strong> true
-</pre><p><strong>Example 5:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1,1]
-<strong>Output:</strong> true
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
diff --git a/problems/monotonic-array/monotonic_array.go b/problems/monotonic-array/monotonic_array.go
deleted file mode 100644
index a2464003e..000000000
--- a/problems/monotonic-array/monotonic_array.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem896
-
-func isMonotonic(A []int) bool {
-	increasing, decreasing := true, true
-	for i, v := range A[1:] {
-		if v > A[i] {
-			decreasing = false
-		} else if v < A[i] {
-			increasing = false
-		}
-	}
-	return increasing || decreasing
-}
diff --git a/problems/monotonic-array/monotonic_array_test.go b/problems/monotonic-array/monotonic_array_test.go
deleted file mode 100644
index 05de2c01d..000000000
--- a/problems/monotonic-array/monotonic_array_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem896
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestIsMonotonic(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 2, 3},
-			want: true,
-		},
-		{
-			in:   []int{6, 5, 4, 4},
-			want: true,
-		},
-		{
-			in:   []int{1, 3, 2},
-			want: false,
-		},
-		{
-			in:   []int{1, 2, 4, 5},
-			want: true,
-		},
-		{
-			in:   []int{1, 1, 1},
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 3, 3, 3, 2, 1},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isMonotonic(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/monthly-transactions-i/README.md b/problems/monthly-transactions-i/README.md
deleted file mode 100644
index 7eaff3dbd..000000000
--- a/problems/monthly-transactions-i/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../critical-connections-in-a-network "Critical Connections in a Network")
-　　　　　　　　　　　　　　　　
-[Next >](../tournament-winners "Tournament Winners")
-
-## [1193. Monthly Transactions I (Medium)](https://leetcode.com/problems/monthly-transactions-i "每月交易 I")
-
-<p>Table: <code>Transactions</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| country       | varchar |
-| state         | enum    |
-| amount        | int     |
-| trans_date    | date    |
-+---------------+---------+
-id is the primary key of this table.
-The table has information about incoming transactions.
-The state column is an enum of type [&quot;approved&quot;, &quot;declined&quot;].
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find for each month and country, the number of transactions and their total amount, the number of approved transactions and their total amount.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-<code>Transactions</code> table:
-+------+---------+----------+--------+------------+
-| id   | country | state    | amount | trans_date |
-+------+---------+----------+--------+------------+
-| 121  | US      | approved | 1000   | 2018-12-18 |
-| 122  | US      | declined | 2000   | 2018-12-19 |
-| 123  | US      | approved | 2000   | 2019-01-01 |
-| 124  | DE      | approved | 2000   | 2019-01-07 |
-+------+---------+----------+--------+------------+
-
-Result table:
-+----------+---------+-------------+----------------+--------------------+-----------------------+
-| month    | country | trans_count | approved_count | trans_total_amount | approved_total_amount |
-+----------+---------+-------------+----------------+--------------------+-----------------------+
-| 2018-12  | US      | 2           | 1              | 3000               | 1000                  |
-| 2019-01  | US      | 1           | 1              | 2000               | 2000                  |
-| 2019-01  | DE      | 1           | 1              | 2000               | 2000                  |
-+----------+---------+-------------+----------------+--------------------+-----------------------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/monthly-transactions-i/mysql_schemas.sql b/problems/monthly-transactions-i/mysql_schemas.sql
deleted file mode 100644
index f46d70e2f..000000000
--- a/problems/monthly-transactions-i/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Transactions (id int, country varchar(4), state enum('approved', 'declined'), amount int, trans_date date);
-Truncate table Transactions;
-insert into Transactions (id, country, state, amount, trans_date) values ('121', 'US', 'approved', '1000', '2018-12-18');
-insert into Transactions (id, country, state, amount, trans_date) values ('122', 'US', 'declined', '2000', '2018-12-19');
-insert into Transactions (id, country, state, amount, trans_date) values ('123', 'US', 'approved', '2000', '2019-01-01');
-insert into Transactions (id, country, state, amount, trans_date) values ('124', 'DE', 'approved', '2000', '2019-01-07');
diff --git a/problems/monthly-transactions-ii/README.md b/problems/monthly-transactions-ii/README.md
deleted file mode 100644
index 8662b3c72..000000000
--- a/problems/monthly-transactions-ii/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../last-person-to-fit-in-the-bus "Last Person to Fit in the Bus")
-　　　　　　　　　　　　　　　　
-[Next >](../design-skiplist "Design Skiplist")
-
-## [1205. Monthly Transactions II (Medium)](https://leetcode.com/problems/monthly-transactions-ii "每月交易II")
-
-<p>Table: <code>Transactions</code></p>
-
-<pre>
-+----------------+---------+
-| Column Name    | Type    |
-+----------------+---------+
-| id             | int     |
-| country        | varchar |
-| state          | enum    |
-| amount         | int     |
-| trans_date     | date    |
-+----------------+---------+
-id is the primary key of this table.
-The table has information about incoming transactions.
-The state column is an enum of type [&quot;approved&quot;, &quot;declined&quot;].
-</pre>
-
-<p>Table: <code>Chargebacks</code></p>
-
-<pre>
-+----------------+---------+
-| Column Name    | Type    |
-+----------------+---------+
-| trans_id       | int     |
-| charge_date    | date    |
-+----------------+---------+
-Chargebacks contains basic information regarding incoming chargebacks from some transactions placed in Transactions table.
-trans_id is a foreign key to the id column of Transactions table.
-Each chargeback corresponds to a transaction made previously even if they were not approved.</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find for each month and country, the number of approved transactions and their total amount, the number of chargebacks and their total amount.</p>
-
-<p><strong>Note</strong>: In your&nbsp;query, given the month and country, ignore&nbsp;rows with all&nbsp;zeros.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-<code>Transactions</code> table:
-+------+---------+----------+--------+------------+
-| id   | country | state    | amount | trans_date |
-+------+---------+----------+--------+------------+
-| 101  | US      | approved | 1000   | 2019-05-18 |
-| 102  | US      | declined | 2000   | 2019-05-19 |
-| 103  | US      | approved | 3000   | 2019-06-10 |
-| 104  | US      | approved | 4000   | 2019-06-13 |
-| 105  | US      | approved | 5000   | 2019-06-15 |
-+------+---------+----------+--------+------------+
-
-<code>Chargebacks</code> table:
-+------------+------------+
-| trans_id   | trans_date |
-+------------+------------+
-| 102        | 2019-05-29 |
-| 101        | 2019-06-30 |
-| 105        | 2019-09-18 |
-+------------+------------+
-
-Result table:
-+----------+---------+----------------+-----------------+-------------------+--------------------+
-| month    | country | approved_count | approved_amount | chargeback_count  | chargeback_amount  |
-+----------+---------+----------------+-----------------+-------------------+--------------------+
-| 2019-05  | US      | 1              | 1000            | 1                 | 2000               |
-| 2019-06  | US      | 3              | 12000           | 1                 | 1000               |
-| 2019-09  | US      | 0              | 0               | 1                 | 5000               |
-+----------+---------+----------------+-----------------+-------------------+--------------------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Monthly Transactions I](../monthly-transactions-i) (Medium)
diff --git a/problems/monthly-transactions-ii/mysql_schemas.sql b/problems/monthly-transactions-ii/mysql_schemas.sql
deleted file mode 100644
index d73b157c0..000000000
--- a/problems/monthly-transactions-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,14 +0,0 @@
-Create table If Not Exists Transactions (id int, country varchar(4), state enum('approved', 'declined'), amount int, trans_date date)
-;
-Create table If Not Exists Chargebacks (trans_id int, trans_date date)
-;
-Truncate table Transactions;
-insert into Transactions (id, country, state, amount, trans_date) values ('101', 'US', 'approved', '1000', '2019-05-18');
-insert into Transactions (id, country, state, amount, trans_date) values ('102', 'US', 'declined', '2000', '2019-05-19');
-insert into Transactions (id, country, state, amount, trans_date) values ('103', 'US', 'approved', '3000', '2019-06-10');
-insert into Transactions (id, country, state, amount, trans_date) values ('104', 'US', 'declined', '4000', '2019-06-13');
-insert into Transactions (id, country, state, amount, trans_date) values ('105', 'US', 'approved', '5000', '2019-06-15');
-Truncate table Chargebacks;
-insert into Chargebacks (trans_id, trans_date) values ('102', '2019-05-29');
-insert into Chargebacks (trans_id, trans_date) values ('101', '2019-06-30');
-insert into Chargebacks (trans_id, trans_date) values ('105', '2019-09-18');
diff --git a/problems/most-beautiful-item-for-each-query/README.md b/problems/most-beautiful-item-for-each-query/README.md
deleted file mode 100644
index 4322b3b80..000000000
--- a/problems/most-beautiful-item-for-each-query/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../walking-robot-simulation-ii "Walking Robot Simulation II")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-tasks-you-can-assign "Maximum Number of Tasks You Can Assign")
-
-## [2070. Most Beautiful Item for Each Query (Medium)](https://leetcode.com/problems/most-beautiful-item-for-each-query "每一个查询的最大美丽值")
-
-<p>You are given a 2D integer array <code>items</code> where <code>items[i] = [price<sub>i</sub>, beauty<sub>i</sub>]</code> denotes the <strong>price</strong> and <strong>beauty</strong> of an item respectively.</p>
-
-<p>You are also given a <strong>0-indexed</strong> integer array <code>queries</code>. For each <code>queries[j]</code>, you want to determine the <strong>maximum beauty</strong> of an item whose <strong>price</strong> is <strong>less than or equal</strong> to <code>queries[j]</code>. If no such item exists, then the answer to this query is <code>0</code>.</p>
-
-<p>Return <em>an array </em><code>answer</code><em> of the same length as </em><code>queries</code><em> where </em><code>answer[j]</code><em> is the answer to the </em><code>j<sup>th</sup></code><em> query</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> items = [[1,2],[3,2],[2,4],[5,6],[3,5]], queries = [1,2,3,4,5,6]
-<strong>Output:</strong> [2,4,5,5,6,6]
-<strong>Explanation:</strong>
-- For queries[0]=1, [1,2] is the only item which has price &lt;= 1. Hence, the answer for this query is 2.
-- For queries[1]=2, the items which can be considered are [1,2] and [2,4]. 
-  The maximum beauty among them is 4.
-- For queries[2]=3 and queries[3]=4, the items which can be considered are [1,2], [3,2], [2,4], and [3,5].
-  The maximum beauty among them is 5.
-- For queries[4]=5 and queries[5]=6, all items can be considered.
-  Hence, the answer for them is the maximum beauty of all items, i.e., 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> items = [[1,2],[1,2],[1,3],[1,4]], queries = [1]
-<strong>Output:</strong> [4]
-<strong>Explanation:</strong> 
-The price of every item is equal to 1, so we choose the item with the maximum beauty 4. 
-Note that multiple items can have the same price and/or beauty.  
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> items = [[10,1000]], queries = [5]
-<strong>Output:</strong> [0]
-<strong>Explanation:</strong>
-No item has a price less than or equal to 5, so no item can be chosen.
-Hence, the answer to the query is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= items.length, queries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>items[i].length == 2</code></li>
-	<li><code>1 &lt;= price<sub>i</sub>, beauty<sub>i</sub>, queries[j] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we process the queries in a smart order to avoid repeatedly checking the same items?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we use the answer to a query for other queries?
-</details>
diff --git a/problems/most-common-word/README.md b/problems/most-common-word/README.md
deleted file mode 100644
index 2d6aeb918..000000000
--- a/problems/most-common-word/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../race-car "Race Car")
-　　　　　　　　　　　　　　　　
-[Next >](../short-encoding-of-words "Short Encoding of Words")
-
-## [819. Most Common Word (Easy)](https://leetcode.com/problems/most-common-word "最常见的单词")
-
-<p>Given a string <code>paragraph</code> and a string array of the banned words <code>banned</code>, return <em>the most frequent word that is not banned</em>. It is <strong>guaranteed</strong> there is <strong>at least one word</strong> that is not banned, and that the answer is <strong>unique</strong>.</p>
-
-<p>The words in <code>paragraph</code> are <strong>case-insensitive</strong> and the answer should be returned in <strong>lowercase</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> paragraph = &quot;Bob hit a ball, the hit BALL flew far after it was hit.&quot;, banned = [&quot;hit&quot;]
-<strong>Output:</strong> &quot;ball&quot;
-<strong>Explanation:</strong> 
-&quot;hit&quot; occurs 3 times, but it is a banned word.
-&quot;ball&quot; occurs twice (and no other word does), so it is the most frequent non-banned word in the paragraph. 
-Note that words in the paragraph are not case sensitive,
-that punctuation is ignored (even if adjacent to words, such as &quot;ball,&quot;), 
-and that &quot;hit&quot; isn&#39;t the answer even though it occurs more because it is banned.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> paragraph = &quot;a.&quot;, banned = []
-<strong>Output:</strong> &quot;a&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= paragraph.length &lt;= 1000</code></li>
-	<li>paragraph consists of English letters, space <code>&#39; &#39;</code>, or one of the symbols: <code>&quot;!?&#39;,;.&quot;</code>.</li>
-	<li><code>0 &lt;= banned.length &lt;= 100</code></li>
-	<li><code>1 &lt;= banned[i].length &lt;= 10</code></li>
-	<li><code>banned[i]</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/most-common-word/most_common_word.go b/problems/most-common-word/most_common_word.go
deleted file mode 100644
index f8f4aa9af..000000000
--- a/problems/most-common-word/most_common_word.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem819
-
-import (
-	"regexp"
-	"strings"
-)
-
-func mostCommonWord(paragraph string, banned []string) string {
-	words := make([]string, 0)
-	paragraph = strings.ToLower(paragraph)
-	reg := regexp.MustCompile(`[a-z]+`)
-	for _, word := range reg.FindAllString(paragraph, -1) {
-		words = append(words, word)
-	}
-	mb := make(map[string]bool)
-	for _, ban := range banned {
-		mb[ban] = true
-	}
-	ans, max, count := "", 0, make(map[string]int)
-	for _, word := range words {
-		if !mb[word] {
-			count[word]++
-			if count[word] > max {
-				max = count[word]
-				ans = word
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/most-common-word/most_common_word_test.go b/problems/most-common-word/most_common_word_test.go
deleted file mode 100644
index 25437752f..000000000
--- a/problems/most-common-word/most_common_word_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem819
-
-import "testing"
-
-type testType struct {
-	paragraph string
-	banned    []string
-	want      string
-}
-
-func TestMostCommonWord(t *testing.T) {
-	tests := [...]testType{
-		{
-			paragraph: "Bob hit a ball, the hit BALL flew far after it was hit.",
-			banned:    []string{"hit"},
-			want:      "ball",
-		},
-		{
-			paragraph: "a, a, a, a, b,b,b,c, c",
-			banned:    []string{"a"},
-			want:      "b",
-		},
-		{
-			paragraph: "Bob",
-			banned:    []string{},
-			want:      "bob",
-		},
-	}
-	for _, tt := range tests {
-		got := mostCommonWord(tt.paragraph, tt.banned)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.paragraph, tt.banned, got, tt.want)
-		}
-	}
-}
diff --git a/problems/most-frequent-subtree-sum/README.md b/problems/most-frequent-subtree-sum/README.md
deleted file mode 100644
index be2cc3453..000000000
--- a/problems/most-frequent-subtree-sum/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../perfect-number "Perfect Number")
-　　　　　　　　　　　　　　　　
-[Next >](../fibonacci-number "Fibonacci Number")
-
-## [508. Most Frequent Subtree Sum (Medium)](https://leetcode.com/problems/most-frequent-subtree-sum "出现次数最多的子树元素和")
-
-<p>Given the <code>root</code> of a binary tree, return the most frequent <strong>subtree sum</strong>. If there is a tie, return all the values with the highest frequency in any order.</p>
-
-<p>The <strong>subtree sum</strong> of a node is defined as the sum of all the node values formed by the subtree rooted at that node (including the node itself).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/freq1-tree.jpg" style="width: 207px; height: 183px;" />
-<pre>
-<strong>Input:</strong> root = [5,2,-3]
-<strong>Output:</strong> [2,-3,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/freq2-tree.jpg" style="width: 207px; height: 183px;" />
-<pre>
-<strong>Input:</strong> root = [5,2,-5]
-<strong>Output:</strong> [2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Subtree of Another Tree](../subtree-of-another-tree) (Easy)
-  1. [Count Nodes Equal to Sum of Descendants](../count-nodes-equal-to-sum-of-descendants) (Medium)
diff --git a/problems/most-frequent-subtree-sum/most_frequent_subtree_sum.go b/problems/most-frequent-subtree-sum/most_frequent_subtree_sum.go
deleted file mode 100644
index 7a96419af..000000000
--- a/problems/most-frequent-subtree-sum/most_frequent_subtree_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem508
diff --git a/problems/most-frequent-subtree-sum/most_frequent_subtree_sum_test.go b/problems/most-frequent-subtree-sum/most_frequent_subtree_sum_test.go
deleted file mode 100644
index 7a96419af..000000000
--- a/problems/most-frequent-subtree-sum/most_frequent_subtree_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem508
diff --git a/problems/most-profit-assigning-work/README.md b/problems/most-profit-assigning-work/README.md
deleted file mode 100644
index ff6912b7e..000000000
--- a/problems/most-profit-assigning-work/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../friends-of-appropriate-ages "Friends Of Appropriate Ages")
-　　　　　　　　　　　　　　　　
-[Next >](../making-a-large-island "Making A Large Island")
-
-## [826. Most Profit Assigning Work (Medium)](https://leetcode.com/problems/most-profit-assigning-work "安排工作以达到最大收益")
-
-<p>You have <code>n</code> jobs and <code>m</code> workers. You are given three arrays: <code>difficulty</code>, <code>profit</code>, and <code>worker</code> where:</p>
-
-<ul>
-	<li><code>difficulty[i]</code> and <code>profit[i]</code> are the difficulty and the profit of the <code>i<sup>th</sup></code> job, and</li>
-	<li><code>worker[j]</code> is the ability of <code>j<sup>th</sup></code> worker (i.e., the <code>j<sup>th</sup></code> worker can only complete a job with difficulty at most <code>worker[j]</code>).</li>
-</ul>
-
-<p>Every worker can be assigned <strong>at most one job</strong>, but one job can be <strong>completed multiple times</strong>.</p>
-
-<ul>
-	<li>For example, if three workers attempt the same job that pays <code>$1</code>, then the total profit will be <code>$3</code>. If a worker cannot complete any job, their profit is <code>$0</code>.</li>
-</ul>
-
-<p>Return the maximum profit we can achieve after assigning the workers to the jobs.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> difficulty = [2,4,6,8,10], profit = [10,20,30,40,50], worker = [4,5,6,7]
-<strong>Output:</strong> 100
-<strong>Explanation:</strong> Workers are assigned jobs of difficulty [4,4,6,6] and they get a profit of [20,20,30,30] separately.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> difficulty = [85,47,57], profit = [24,66,99], worker = [40,25,25]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == difficulty.length</code></li>
-	<li><code>n == profit.length</code></li>
-	<li><code>m == worker.length</code></li>
-	<li><code>1 &lt;= n, m &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= difficulty[i], profit[i], worker[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/most-profit-assigning-work/most_profit_assigning_work.go b/problems/most-profit-assigning-work/most_profit_assigning_work.go
deleted file mode 100644
index 4e9927051..000000000
--- a/problems/most-profit-assigning-work/most_profit_assigning_work.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem826
diff --git a/problems/most-profit-assigning-work/most_profit_assigning_work_test.go b/problems/most-profit-assigning-work/most_profit_assigning_work_test.go
deleted file mode 100644
index 4e9927051..000000000
--- a/problems/most-profit-assigning-work/most_profit_assigning_work_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem826
diff --git a/problems/most-stones-removed-with-same-row-or-column/README.md b/problems/most-stones-removed-with-same-row-or-column/README.md
deleted file mode 100644
index 5c81899d5..000000000
--- a/problems/most-stones-removed-with-same-row-or-column/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../validate-stack-sequences "Validate Stack Sequences")
-　　　　　　　　　　　　　　　　
-[Next >](../bag-of-tokens "Bag of Tokens")
-
-## [947. Most Stones Removed with Same Row or Column (Medium)](https://leetcode.com/problems/most-stones-removed-with-same-row-or-column "移除最多的同行或同列石头")
-
-<p>On a 2D plane, we place <code>n</code> stones at some integer coordinate points. Each coordinate point may have at most one stone.</p>
-
-<p>A stone can be removed if it shares either <strong>the same row or the same column</strong> as another stone that has not been removed.</p>
-
-<p>Given an array <code>stones</code> of length <code>n</code> where <code>stones[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> represents the location of the <code>i<sup>th</sup></code> stone, return <em>the largest possible number of stones that can be removed</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [[0,0],[0,1],[1,0],[1,2],[2,1],[2,2]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> One way to remove 5 stones is as follows:
-1. Remove stone [2,2] because it shares the same row as [2,1].
-2. Remove stone [2,1] because it shares the same column as [0,1].
-3. Remove stone [1,2] because it shares the same row as [1,0].
-4. Remove stone [1,0] because it shares the same column as [0,0].
-5. Remove stone [0,1] because it shares the same row as [0,0].
-Stone [0,0] cannot be removed since it does not share a row/column with another stone still on the plane.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [[0,0],[0,2],[1,1],[2,0],[2,2]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> One way to make 3 moves is as follows:
-1. Remove stone [2,2] because it shares the same row as [2,0].
-2. Remove stone [2,0] because it shares the same column as [0,0].
-3. Remove stone [0,2] because it shares the same row as [0,0].
-Stones [0,0] and [1,1] cannot be removed since they do not share a row/column with another stone still on the plane.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [[0,0]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> [0,0] is the only stone on the plane, so you cannot remove it.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= stones.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li>No two stones are at the same coordinate point.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
diff --git a/problems/most-stones-removed-with-same-row-or-column/most_stones_removed_with_same_row_or_column.go b/problems/most-stones-removed-with-same-row-or-column/most_stones_removed_with_same_row_or_column.go
deleted file mode 100644
index 3af3ac94e..000000000
--- a/problems/most-stones-removed-with-same-row-or-column/most_stones_removed_with_same_row_or_column.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem947
diff --git a/problems/most-stones-removed-with-same-row-or-column/most_stones_removed_with_same_row_or_column_test.go b/problems/most-stones-removed-with-same-row-or-column/most_stones_removed_with_same_row_or_column_test.go
deleted file mode 100644
index 3af3ac94e..000000000
--- a/problems/most-stones-removed-with-same-row-or-column/most_stones_removed_with_same_row_or_column_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem947
diff --git a/problems/most-visited-sector-in-a-circular-track/README.md b/problems/most-visited-sector-in-a-circular-track/README.md
deleted file mode 100644
index dde19d99c..000000000
--- a/problems/most-visited-sector-in-a-circular-track/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../detect-cycles-in-2d-grid "Detect Cycles in 2D Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-coins-you-can-get "Maximum Number of Coins You Can Get")
-
-## [1560. Most Visited Sector in  a Circular Track (Easy)](https://leetcode.com/problems/most-visited-sector-in-a-circular-track "圆形赛道上经过次数最多的扇区")
-
-<p>Given an integer <code>n</code> and an integer array <code>rounds</code>. We have a circular track which consists of <code>n</code> sectors labeled from <code>1</code> to <code>n</code>. A marathon will be held on this track, the marathon consists of <code>m</code> rounds. The <code>i<sup>th</sup></code> round starts at sector <code>rounds[i - 1]</code> and ends at sector <code>rounds[i]</code>. For example, round 1 starts at sector <code>rounds[0]</code> and ends at sector <code>rounds[1]</code></p>
-
-<p>Return <em>an array of the most visited sectors</em> sorted in <strong>ascending</strong> order.</p>
-
-<p>Notice that you circulate the track in ascending order of sector numbers in the counter-clockwise direction (See the first example).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/14/tmp.jpg" style="width: 433px; height: 341px;" />
-<pre>
-<strong>Input:</strong> n = 4, rounds = [1,3,1,2]
-<strong>Output:</strong> [1,2]
-<strong>Explanation:</strong> The marathon starts at sector 1. The order of the visited sectors is as follows:
-1 --&gt; 2 --&gt; 3 (end of round 1) --&gt; 4 --&gt; 1 (end of round 2) --&gt; 2 (end of round 3 and the marathon)
-We can see that both sectors 1 and 2 are visited twice and they are the most visited sectors. Sectors 3 and 4 are visited only once.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, rounds = [2,1,2,1,2,1,2,1,2]
-<strong>Output:</strong> [2]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7, rounds = [1,3,5,7]
-<strong>Output:</strong> [1,2,3,4,5,6,7]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= m &lt;= 100</code></li>
-	<li><code>rounds.length == m + 1</code></li>
-	<li><code>1 &lt;= rounds[i] &lt;= n</code></li>
-	<li><code>rounds[i] != rounds[i + 1]</code> for <code>0 &lt;= i &lt; m</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each round increment the visits of the sectors visited during the marathon with 1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Determine the max number of visits, and return any sector visited the max number of visits.
-</details>
diff --git a/problems/move-sub-tree-of-n-ary-tree/README.md b/problems/move-sub-tree-of-n-ary-tree/README.md
deleted file mode 100644
index a6afdc459..000000000
--- a/problems/move-sub-tree-of-n-ary-tree/README.md
+++ /dev/null
@@ -1,37 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-position-for-a-service-centre "Best Position for a Service Centre")
-　　　　　　　　　　　　　　　　
-[Next >](../find-users-with-valid-e-mails "Find Users With Valid E-Mails")
-
-## [1516. Move Sub-Tree of N-Ary Tree (Hard)](https://leetcode.com/problems/move-sub-tree-of-n-ary-tree "移动 N 叉树的子树")
-
-
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-
-### Similar Questions
-  1. [Find Root of N-Ary Tree](../find-root-of-n-ary-tree) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Disconnect node p from its parent and append it to the children list of node q.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If q was in the sub-tree of node p (case 1), get the parent node of p and replace p in its children list with q.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If p was the root of the tree, make q the root of the tree.
-</details>
diff --git a/problems/move-zeroes/README.md b/problems/move-zeroes/README.md
deleted file mode 100644
index 78420e9e4..000000000
--- a/problems/move-zeroes/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../expression-add-operators "Expression Add Operators")
-　　　　　　　　　　　　　　　　
-[Next >](../peeking-iterator "Peeking Iterator")
-
-## [283. Move Zeroes (Easy)](https://leetcode.com/problems/move-zeroes "移动零")
-
-<p>Given an integer array <code>nums</code>, move all <code>0</code>&#39;s to the end of it while maintaining the relative order of the non-zero elements.</p>
-
-<p><strong>Note</strong> that you must do this in-place without making a copy of the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [0,1,0,3,12]
-<strong>Output:</strong> [1,3,12,0,0]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [0]
-<strong>Output:</strong> [0]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you minimize the total number of operations done?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Remove Element](../remove-element) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-<b>In-place</b> means we should not be allocating any space for extra array. But we are allowed to modify the existing array. However, as a first step, try coming up with a solution that makes use of additional space. For this problem as well, first apply the idea discussed using an additional array and the in-place solution will pop up eventually.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-A <b>two-pointer</b> approach could be helpful here. The idea would be to have one pointer for iterating the array and another pointer that just works on the non-zero elements of the array.
-</details>
diff --git a/problems/move-zeroes/move_zeroes.go b/problems/move-zeroes/move_zeroes.go
deleted file mode 100644
index f170ed9bc..000000000
--- a/problems/move-zeroes/move_zeroes.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem283
-
-func moveZeroes(nums []int) {
-	insertAt := 0
-	for i, v := range nums {
-		if v != 0 {
-			if i != insertAt {
-				nums[insertAt] = v
-				nums[i] = 0
-			}
-			insertAt++
-		}
-	}
-}
diff --git a/problems/move-zeroes/move_zeroes_test.go b/problems/move-zeroes/move_zeroes_test.go
deleted file mode 100644
index 56f5ea626..000000000
--- a/problems/move-zeroes/move_zeroes_test.go
+++ /dev/null
@@ -1,37 +0,0 @@
-package problem283
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestMoveZeroes(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{0, 1, 0, 3, 12},
-			want: []int{1, 3, 12, 0, 0},
-		},
-		{
-			in:   []int{0, 1, 0, 2, 3, 3, 0, 7, 8},
-			want: []int{1, 2, 3, 3, 7, 8, 0, 0, 0},
-		},
-		{
-			in:   []int{1, 2, 3, 4, 5},
-			want: []int{1, 2, 3, 4, 5},
-		},
-	}
-
-	for _, tt := range tests {
-		got := make([]int, len(tt.in))
-		copy(got, tt.in)
-		moveZeroes(got)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/movie-rating/README.md b/problems/movie-rating/README.md
deleted file mode 100644
index 92060fa44..000000000
--- a/problems/movie-rating/README.md
+++ /dev/null
@@ -1,109 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../jump-game-v "Jump Game V")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-steps-to-reduce-a-number-to-zero "Number of Steps to Reduce a Number to Zero")
-
-## [1341. Movie Rating (Medium)](https://leetcode.com/problems/movie-rating "电影评分")
-
-<p>Table: <code>Movies</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| movie_id      | int     |
-| title         | varchar |
-+---------------+---------+
-movie_id is the primary key for this table.
-title is the name of the movie.
-</pre>
-
-<p>Table: <code>Users</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| user_id       | int     |
-| name          | varchar |
-+---------------+---------+
-user_id is the primary key for this table.
-</pre>
-
-<p>Table: <code>Movie_Rating</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| movie_id      | int     |
-| user_id       | int     |
-| rating        | int     |
-| created_at    | date    |
-+---------------+---------+
-(movie_id, user_id) is the primary key for this table.
-This table contains the rating of a movie by a user in their review.
-created_at is the user's review date. 
-</pre>
- 
-Write the following SQL query:
-
-- Find the name of the user who has rated the greatest number of the movies.
-  In case of a tie, return lexicographically smaller user name.
-
-- Find the movie name with the highest average rating as of Feb 2020.
-  In case of a tie, return lexicographically smaller movie name..
-
-Query is returned in 2 rows, the query result format is in the folowing example:
-<pre>
-Movie table:
-+-------------+--------------+
-| movie_id    |  title       |
-+-------------+--------------+
-| 1           | Avengers     |
-| 2           | Frozen 2     |
-| 3           | Joker        |
-+-------------+--------------+
-
-Users table:
-+-------------+--------------+
-| user_id     |  name        |
-+-------------+--------------+
-| 1           | Daniel       |
-| 2           | Monica       |
-| 3           | Maria        |
-| 4           | James        |
-+-------------+--------------+
-
-Movie_Rating table:
-+-------------+--------------+--------------+-------------+
-| movie_id    | user_id      | rating       | created_at  |
-+-------------+--------------+--------------+-------------+
-| 1           | 1            | 3            | 2020-01-12  |
-| 1           | 2            | 4            | 2020-02-11  |
-| 1           | 3            | 2            | 2020-02-12  |
-| 1           | 4            | 1            | 2020-01-01  |
-| 2           | 1            | 5            | 2020-02-17  | 
-| 2           | 2            | 2            | 2020-02-01  | 
-| 2           | 3            | 2            | 2020-03-01  |
-| 3           | 1            | 3            | 2020-02-22  | 
-| 3           | 2            | 4            | 2020-02-25  | 
-+-------------+--------------+--------------+-------------+
-
-Result table:
-+--------------+
-| results      |
-+--------------+
-| Daniel       |
-| Frozen 2     |
-+--------------+
-
-Daniel and Maria have rated 3 movies ("Avengers", "Frozen 2" and "Joker") but Daniel is smaller lexicographically.
-Frozen 2 and Joker have a rating average of 3.5 in February but Frozen 2 is smaller lexicographically.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/movie-rating/mysql_schemas.sql b/problems/movie-rating/mysql_schemas.sql
deleted file mode 100644
index 7f1cf7c36..000000000
--- a/problems/movie-rating/mysql_schemas.sql
+++ /dev/null
@@ -1,22 +0,0 @@
-Create table If Not Exists Movies (movie_id int, title varchar(30));
-Create table If Not Exists Users (user_id int, name varchar(30));
-Create table If Not Exists MovieRating (movie_id int, user_id int, rating int, created_at date);
-Truncate table Movies;
-insert into Movies (movie_id, title) values ('1', 'Avengers');
-insert into Movies (movie_id, title) values ('2', 'Frozen 2');
-insert into Movies (movie_id, title) values ('3', 'Joker');
-Truncate table Users;
-insert into Users (user_id, name) values ('1', 'Daniel');
-insert into Users (user_id, name) values ('2', 'Monica');
-insert into Users (user_id, name) values ('3', 'Maria');
-insert into Users (user_id, name) values ('4', 'James');
-Truncate table MovieRating;
-insert into MovieRating (movie_id, user_id, rating, created_at) values ('1', '1', '3', '2020-01-12');
-insert into MovieRating (movie_id, user_id, rating, created_at) values ('1', '2', '4', '2020-02-11');
-insert into MovieRating (movie_id, user_id, rating, created_at) values ('1', '3', '2', '2020-02-12');
-insert into MovieRating (movie_id, user_id, rating, created_at) values ('1', '4', '1', '2020-01-01');
-insert into MovieRating (movie_id, user_id, rating, created_at) values ('2', '1', '5', '2020-02-17');
-insert into MovieRating (movie_id, user_id, rating, created_at) values ('2', '2', '2', '2020-02-01');
-insert into MovieRating (movie_id, user_id, rating, created_at) values ('2', '3', '2', '2020-03-01');
-insert into MovieRating (movie_id, user_id, rating, created_at) values ('3', '1', '3', '2020-02-22');
-insert into MovieRating (movie_id, user_id, rating, created_at) values ('3', '2', '4', '2020-02-25');
diff --git a/problems/moving-average-from-data-stream/README.md b/problems/moving-average-from-data-stream/README.md
deleted file mode 100644
index d114871ff..000000000
--- a/problems/moving-average-from-data-stream/README.md
+++ /dev/null
@@ -1,32 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-vowels-of-a-string "Reverse Vowels of a String")
-　　　　　　　　　　　　　　　　
-[Next >](../top-k-frequent-elements "Top K Frequent Elements")
-
-## [346. Moving Average from Data Stream (Easy)](https://leetcode.com/problems/moving-average-from-data-stream "数据流中的移动平均值")
-
-<p>Given a stream of integers and a window size, calculate the moving average of all integers in the sliding window.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-MovingAverage m = new MovingAverage(3);
-m.next(1) = 1
-m.next(10) = (1 + 10) / 2
-m.next(3) = (1 + 10 + 3) / 3
-m.next(5) = (10 + 3 + 5) / 3
-</pre>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
diff --git a/problems/moving-average-from-data-stream/moving_average_from_data_stream.go b/problems/moving-average-from-data-stream/moving_average_from_data_stream.go
deleted file mode 100644
index 7209c5086..000000000
--- a/problems/moving-average-from-data-stream/moving_average_from_data_stream.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem346
diff --git a/problems/moving-average-from-data-stream/moving_average_from_data_stream_test.go b/problems/moving-average-from-data-stream/moving_average_from_data_stream_test.go
deleted file mode 100644
index 7209c5086..000000000
--- a/problems/moving-average-from-data-stream/moving_average_from_data_stream_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem346
diff --git a/problems/moving-stones-until-consecutive-ii/README.md b/problems/moving-stones-until-consecutive-ii/README.md
deleted file mode 100644
index 23713bb67..000000000
--- a/problems/moving-stones-until-consecutive-ii/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-score-triangulation-of-polygon "Minimum Score Triangulation of Polygon")
-　　　　　　　　　　　　　　　　
-[Next >](../robot-bounded-in-circle "Robot Bounded In Circle")
-
-## [1040. Moving Stones Until Consecutive II (Medium)](https://leetcode.com/problems/moving-stones-until-consecutive-ii "移动石子直到连续 II")
-
-<p>There are some stones in different positions on the X-axis. You are given an integer array <code>stones</code>, the positions of the stones.</p>
-
-<p>Call a stone an <strong>endpoint stone</strong> if it has the smallest or largest position. In one move, you pick up an <strong>endpoint stone</strong> and move it to an unoccupied position so that it is no longer an <strong>endpoint stone</strong>.</p>
-
-<ul>
-	<li>In particular, if the stones are at say, <code>stones = [1,2,5]</code>, you cannot move the endpoint stone at position <code>5</code>, since moving it to any position (such as <code>0</code>, or <code>3</code>) will still keep that stone as an endpoint stone.</li>
-</ul>
-
-<p>The game ends when you cannot make any more moves (i.e., the stones are in three consecutive positions).</p>
-
-<p>Return <em>an integer array </em><code>answer</code><em> of length </em><code>2</code><em> where</em>:</p>
-
-<ul>
-	<li><code>answer[0]</code> <em>is the minimum number of moves you can play, and</em></li>
-	<li><code>answer[1]</code> <em>is the maximum number of moves you can play</em>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [7,4,9]
-<strong>Output:</strong> [1,2]
-<strong>Explanation:</strong> We can move 4 -&gt; 8 for one move to finish the game.
-Or, we can move 9 -&gt; 5, 4 -&gt; 6 for two moves to finish the game.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [6,5,4,3,10]
-<strong>Output:</strong> [2,3]
-<strong>Explanation:</strong> We can move 3 -&gt; 8 then 10 -&gt; 7 to finish the game.
-Or, we can move 3 -&gt; 7, 4 -&gt; 8, 5 -&gt; 9 to finish the game.
-Notice we cannot move 10 -&gt; 2 to finish the game, because that would be an illegal move.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= stones.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= stones[i] &lt;= 10<sup>9</sup></code></li>
-	<li>All the values of <code>stones</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For the minimum, how many cows are already in place?
-For the maximum, we have to lose either the gap A[1] - A[0] or A[N-1] - A[N-2]  (where N = A.length), but every other space can be occupied.
-</details>
diff --git a/problems/moving-stones-until-consecutive-ii/moving_stones_until_consecutive_ii.go b/problems/moving-stones-until-consecutive-ii/moving_stones_until_consecutive_ii.go
deleted file mode 100644
index 542543e1c..000000000
--- a/problems/moving-stones-until-consecutive-ii/moving_stones_until_consecutive_ii.go
+++ /dev/null
@@ -1,42 +0,0 @@
-package problem1040
-
-import "sort"
-
-func numMovesStonesII(stones []int) []int {
-	sort.Ints(stones)
-	return []int{low(stones), high(stones)}
-}
-
-func high(s []int) int {
-	n := len(s)
-	return max(s[n-1]-s[1], s[n-2]-s[0]) - n + 2
-}
-
-func low(s []int) int {
-	n := len(s)
-	// corner case
-	if (s[n-2]-s[0] == n-2 && s[n-1]-s[n-2] > 2) ||
-		(s[n-1]-s[1] == n-2 && s[1]-s[0] > 2) {
-		return 2
-	}
-	// sliding window is s[i:j]
-	width, i, j := 0, 0, 1
-	for ; j < n; j++ {
-		if s[j]-s[i] < n {
-			continue
-		}
-		width = max(width, j-i)
-		i = j
-	}
-	width = max(width, j-i)
-	// finally, all stone move into maxWidth windows
-	// so need move n-width stones
-	return n - width
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/moving-stones-until-consecutive/README.md b/problems/moving-stones-until-consecutive/README.md
deleted file mode 100644
index ed4929f36..000000000
--- a/problems/moving-stones-until-consecutive/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stream-of-characters "Stream of Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../coloring-a-border "Coloring A Border")
-
-## [1033. Moving Stones Until Consecutive (Medium)](https://leetcode.com/problems/moving-stones-until-consecutive "移动石子直到连续")
-
-<p>There are three stones in different positions on the X-axis. You are given three integers <code>a</code>, <code>b</code>, and <code>c</code>, the positions of the stones.</p>
-
-<p>In one move, you pick up a stone at an endpoint (i.e., either the lowest or highest position stone), and move it to an unoccupied position between those endpoints. Formally, let&#39;s say the stones are currently at positions <code>x</code>, <code>y</code>, and <code>z</code> with <code>x &lt; y &lt; z</code>. You pick up the stone at either position <code>x</code> or position <code>z</code>, and move that stone to an integer position <code>k</code>, with <code>x &lt; k &lt; z</code> and <code>k != y</code>.</p>
-
-<p>The game ends when you cannot make any more moves (i.e., the stones are in three consecutive positions).</p>
-
-<p>Return <em>an integer array </em><code>answer</code><em> of length </em><code>2</code><em> where</em>:</p>
-
-<ul>
-	<li><code>answer[0]</code> <em>is the minimum number of moves you can play, and</em></li>
-	<li><code>answer[1]</code> <em>is the maximum number of moves you can play</em>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 1, b = 2, c = 5
-<strong>Output:</strong> [1,2]
-<strong>Explanation:</strong> Move the stone from 5 to 3, or move the stone from 5 to 4 to 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 4, b = 3, c = 2
-<strong>Output:</strong> [0,0]
-<strong>Explanation:</strong> We cannot make any moves.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 3, b = 5, c = 1
-<strong>Output:</strong> [1,2]
-<strong>Explanation:</strong> Move the stone from 1 to 4; or move the stone from 1 to 2 to 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= a, b, c &lt;= 100</code></li>
-	<li><code>a</code>, <code>b</code>, and <code>c</code> have different values.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Brainteaser](../../tag/brainteaser/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For the minimum:  We can always do it in at most 2 moves, by moving one stone next to another, then the third stone next to the other two.  When can we do it in 1 move?  0 moves?
-
-For the maximum:  Every move, the maximum position minus the minimum position must decrease by at least 1.
-</details>
diff --git a/problems/moving-stones-until-consecutive/moving_stones_until_consecutive.go b/problems/moving-stones-until-consecutive/moving_stones_until_consecutive.go
deleted file mode 100644
index a703f9756..000000000
--- a/problems/moving-stones-until-consecutive/moving_stones_until_consecutive.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1033
-
-var zerozero = []int{0, 0}
-
-func numMovesStones(a, b, c int) []int {
-	a, b, c = sort(a, b, c)
-	if c-a == 2 {
-		return zerozero
-	}
-	minM, maxM := 2, c-a-2
-	if min(b-a, c-b) <= 2 {
-		minM = 1
-	}
-	return []int{minM, maxM}
-}
-
-func sort(a, b, c int) (int, int, int) {
-	if a > b {
-		a, b = b, a
-	}
-	if a > c {
-		a, c = c, a
-	}
-	if b > c {
-		b, c = c, b
-	}
-	return a, b, c
-}
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
diff --git a/problems/multiply-strings/README.md b/problems/multiply-strings/README.md
deleted file mode 100644
index 0a72f5fdf..000000000
--- a/problems/multiply-strings/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../trapping-rain-water "Trapping Rain Water")
-　　　　　　　　　　　　　　　　
-[Next >](../wildcard-matching "Wildcard Matching")
-
-## [43. Multiply Strings (Medium)](https://leetcode.com/problems/multiply-strings "字符串相乘")
-
-<p>Given two non-negative integers <code>num1</code> and <code>num2</code> represented as strings, return the product of <code>num1</code> and <code>num2</code>, also represented as a string.</p>
-
-<p><strong>Note:</strong>&nbsp;You must not use any built-in BigInteger library or convert the inputs to integer directly.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> num1 = "2", num2 = "3"
-<strong>Output:</strong> "6"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> num1 = "123", num2 = "456"
-<strong>Output:</strong> "56088"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num1.length, num2.length &lt;= 200</code></li>
-	<li><code>num1</code> and <code>num2</code> consist of digits only.</li>
-	<li>Both <code>num1</code> and <code>num2</code>&nbsp;do not contain any leading zero, except the number <code>0</code> itself.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Add Two Numbers](../add-two-numbers) (Medium)
-  1. [Plus One](../plus-one) (Easy)
-  1. [Add Binary](../add-binary) (Easy)
-  1. [Add Strings](../add-strings) (Easy)
diff --git a/problems/multiply-strings/multiply_strings.go b/problems/multiply-strings/multiply_strings.go
deleted file mode 100644
index c7056ced3..000000000
--- a/problems/multiply-strings/multiply_strings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem43
diff --git a/problems/multiply-strings/multiply_strings_test.go b/problems/multiply-strings/multiply_strings_test.go
deleted file mode 100644
index c7056ced3..000000000
--- a/problems/multiply-strings/multiply_strings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem43
diff --git a/problems/my-calendar-i/README.md b/problems/my-calendar-i/README.md
deleted file mode 100644
index d8e8ab306..000000000
--- a/problems/my-calendar-i/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../self-dividing-numbers "Self Dividing Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../count-different-palindromic-subsequences "Count Different Palindromic Subsequences")
-
-## [729. My Calendar I (Medium)](https://leetcode.com/problems/my-calendar-i "我的日程安排表 I")
-
-<p>You are implementing a program to use as your calendar. We can add a new event if adding the event will not cause a <strong>double booking</strong>.</p>
-
-<p>A <strong>double booking</strong> happens when two events have some non-empty intersection (i.e., some moment is common to both events.).</p>
-
-<p>The event can be represented as a pair of integers <code>start</code> and <code>end</code> that represents a booking on the half-open interval <code>[start, end)</code>, the range of real numbers <code>x</code> such that <code>start &lt;= x &lt; end</code>.</p>
-
-<p>Implement the <code>MyCalendar</code> class:</p>
-
-<ul>
-	<li><code>MyCalendar()</code> Initializes the calendar object.</li>
-	<li><code>boolean book(int start, int end)</code> Returns <code>true</code> if the event can be added to the calendar successfully without causing a <strong>double booking</strong>. Otherwise, return <code>false</code> and do not add the event to the calendar.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyCalendar&quot;, &quot;book&quot;, &quot;book&quot;, &quot;book&quot;]
-[[], [10, 20], [15, 25], [20, 30]]
-<strong>Output</strong>
-[null, true, false, true]
-
-<strong>Explanation</strong>
-MyCalendar myCalendar = new MyCalendar();
-myCalendar.book(10, 20); // return True
-myCalendar.book(15, 25); // return False, It can not be booked because time 15 is already booked by another event.
-myCalendar.book(20, 30); // return True, The event can be booked, as the first event takes every time less than 20, but not including 20.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= start &lt; end &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>1000</code> calls will be made to <code>book</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [My Calendar II](../my-calendar-ii) (Medium)
-  1. [My Calendar III](../my-calendar-iii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Store the events as a sorted list of intervals.  If none of the events conflict, then the new event can be added.
-</details>
diff --git a/problems/my-calendar-i/my_calendar_i.go b/problems/my-calendar-i/my_calendar_i.go
deleted file mode 100644
index 51b295a00..000000000
--- a/problems/my-calendar-i/my_calendar_i.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem729
diff --git a/problems/my-calendar-i/my_calendar_i_test.go b/problems/my-calendar-i/my_calendar_i_test.go
deleted file mode 100644
index 51b295a00..000000000
--- a/problems/my-calendar-i/my_calendar_i_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem729
diff --git a/problems/my-calendar-ii/README.md b/problems/my-calendar-ii/README.md
deleted file mode 100644
index 07f53d2b3..000000000
--- a/problems/my-calendar-ii/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-different-palindromic-subsequences "Count Different Palindromic Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../my-calendar-iii "My Calendar III")
-
-## [731. My Calendar II (Medium)](https://leetcode.com/problems/my-calendar-ii "我的日程安排表 II")
-
-<p>You are implementing a program to use as your calendar. We can add a new event if adding the event will not cause a <strong>triple booking</strong>.</p>
-
-<p>A <strong>triple booking</strong> happens when three events have some non-empty intersection (i.e., some moment is common to all the three events.).</p>
-
-<p>The event can be represented as a pair of integers <code>start</code> and <code>end</code> that represents a booking on the half-open interval <code>[start, end)</code>, the range of real numbers <code>x</code> such that <code>start &lt;= x &lt; end</code>.</p>
-
-<p>Implement the <code>MyCalendarTwo</code> class:</p>
-
-<ul>
-	<li><code>MyCalendarTwo()</code> Initializes the calendar object.</li>
-	<li><code>boolean book(int start, int end)</code> Returns <code>true</code> if the event can be added to the calendar successfully without causing a <strong>triple booking</strong>. Otherwise, return <code>false</code> and do not add the event to the calendar.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyCalendarTwo&quot;, &quot;book&quot;, &quot;book&quot;, &quot;book&quot;, &quot;book&quot;, &quot;book&quot;, &quot;book&quot;]
-[[], [10, 20], [50, 60], [10, 40], [5, 15], [5, 10], [25, 55]]
-<strong>Output</strong>
-[null, true, true, true, false, true, true]
-
-<strong>Explanation</strong>
-MyCalendarTwo myCalendarTwo = new MyCalendarTwo();
-myCalendarTwo.book(10, 20); // return True, The event can be booked. 
-myCalendarTwo.book(50, 60); // return True, The event can be booked. 
-myCalendarTwo.book(10, 40); // return True, The event can be double booked. 
-myCalendarTwo.book(5, 15);  // return False, The event cannot be booked, because it would result in a triple booking.
-myCalendarTwo.book(5, 10); // return True, The event can be booked, as it does not use time 10 which is already double booked.
-myCalendarTwo.book(25, 55); // return True, The event can be booked, as the time in [25, 40) will be double booked with the third event, the time [40, 50) will be single booked, and the time [50, 55) will be double booked with the second event.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= start &lt; end &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>1000</code> calls will be made to <code>book</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [My Calendar I](../my-calendar-i) (Medium)
-  1. [My Calendar III](../my-calendar-iii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Store two sorted lists of intervals: one list will be all times that are at least single booked, and another list will be all times that are definitely double booked.  If none of the double bookings conflict, then the booking will succeed, and you should update your single and double bookings accordingly.
-</details>
diff --git a/problems/my-calendar-ii/my_calendar_ii.go b/problems/my-calendar-ii/my_calendar_ii.go
deleted file mode 100644
index ff68788d3..000000000
--- a/problems/my-calendar-ii/my_calendar_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem731
diff --git a/problems/my-calendar-ii/my_calendar_ii_test.go b/problems/my-calendar-ii/my_calendar_ii_test.go
deleted file mode 100644
index ff68788d3..000000000
--- a/problems/my-calendar-ii/my_calendar_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem731
diff --git a/problems/my-calendar-iii/README.md b/problems/my-calendar-iii/README.md
deleted file mode 100644
index 16d2e1309..000000000
--- a/problems/my-calendar-iii/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../my-calendar-ii "My Calendar II")
-　　　　　　　　　　　　　　　　
-[Next >](../flood-fill "Flood Fill")
-
-## [732. My Calendar III (Hard)](https://leetcode.com/problems/my-calendar-iii "我的日程安排表 III")
-
-<p>A <code>k</code>-booking happens when <code>k</code> events have some non-empty intersection (i.e., there is some time that is common to all <code>k</code> events.)</p>
-
-<p>You are given some events <code>[start, end)</code>, after each given event, return an integer <code>k</code> representing the maximum <code>k</code>-booking between all the previous events.</p>
-
-<p>Implement the <code>MyCalendarThree</code> class:</p>
-
-<ul>
-	<li><code>MyCalendarThree()</code> Initializes the object.</li>
-	<li><code>int book(int start, int end)</code> Returns an integer <code>k</code> representing the largest integer such that there exists a <code>k</code>-booking in the calendar.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MyCalendarThree&quot;, &quot;book&quot;, &quot;book&quot;, &quot;book&quot;, &quot;book&quot;, &quot;book&quot;, &quot;book&quot;]
-[[], [10, 20], [50, 60], [10, 40], [5, 15], [5, 10], [25, 55]]
-<strong>Output</strong>
-[null, 1, 1, 2, 3, 3, 3]
-
-<strong>Explanation</strong>
-MyCalendarThree myCalendarThree = new MyCalendarThree();
-myCalendarThree.book(10, 20); // return 1, The first event can be booked and is disjoint, so the maximum k-booking is a 1-booking.
-myCalendarThree.book(50, 60); // return 1, The second event can be booked and is disjoint, so the maximum k-booking is a 1-booking.
-myCalendarThree.book(10, 40); // return 2, The third event [10, 40) intersects the first event, and the maximum k-booking is a 2-booking.
-myCalendarThree.book(5, 15); // return 3, The remaining events cause the maximum K-booking to be only a 3-booking.
-myCalendarThree.book(5, 10); // return 3
-myCalendarThree.book(25, 55); // return 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= start &lt; end &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>400</code> calls will be made to <code>book</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [My Calendar I](../my-calendar-i) (Medium)
-  1. [My Calendar II](../my-calendar-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Treat each interval [start, end) as two events "start" and "end", and process them in sorted order.
-</details>
diff --git a/problems/my-calendar-iii/my_calendar_iii.go b/problems/my-calendar-iii/my_calendar_iii.go
deleted file mode 100644
index af2f8d25a..000000000
--- a/problems/my-calendar-iii/my_calendar_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem732
diff --git a/problems/my-calendar-iii/my_calendar_iii_test.go b/problems/my-calendar-iii/my_calendar_iii_test.go
deleted file mode 100644
index af2f8d25a..000000000
--- a/problems/my-calendar-iii/my_calendar_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem732
diff --git a/problems/n-ary-tree-level-order-traversal/README.md b/problems/n-ary-tree-level-order-traversal/README.md
deleted file mode 100644
index cf206b66c..000000000
--- a/problems/n-ary-tree-level-order-traversal/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../serialize-and-deserialize-n-ary-tree "Serialize and Deserialize N-ary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../flatten-a-multilevel-doubly-linked-list "Flatten a Multilevel Doubly Linked List")
-
-## [429. N-ary Tree Level Order Traversal (Medium)](https://leetcode.com/problems/n-ary-tree-level-order-traversal "N 叉树的层序遍历")
-
-<p>Given an n-ary tree, return the <em>level order</em> traversal of its nodes&#39; values.</p>
-
-<p><em>Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img src="https://assets.leetcode.com/uploads/2018/10/12/narytreeexample.png" style="width: 100%; max-width: 300px;" /></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,3,2,4,null,5,6]
-<strong>Output:</strong> [[1],[3,2,4],[5,6]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/11/08/sample_4_964.png" style="width: 296px; height: 241px;" /></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
-<strong>Output:</strong> [[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The height of the n-ary tree is less than or equal to <code>1000</code></li>
-	<li>The total number of nodes is between <code>[0, 10<sup>4</sup>]</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Level Order Traversal](../binary-tree-level-order-traversal) (Medium)
-  1. [N-ary Tree Preorder Traversal](../n-ary-tree-preorder-traversal) (Easy)
-  1. [N-ary Tree Postorder Traversal](../n-ary-tree-postorder-traversal) (Easy)
diff --git a/problems/n-ary-tree-level-order-traversal/n_ary_tree_level_order_traversal.go b/problems/n-ary-tree-level-order-traversal/n_ary_tree_level_order_traversal.go
deleted file mode 100644
index 2b84bcaab..000000000
--- a/problems/n-ary-tree-level-order-traversal/n_ary_tree_level_order_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem429
diff --git a/problems/n-ary-tree-level-order-traversal/n_ary_tree_level_order_traversal.py b/problems/n-ary-tree-level-order-traversal/n_ary_tree_level_order_traversal.py
deleted file mode 100755
index 391ed36b5..000000000
--- a/problems/n-ary-tree-level-order-traversal/n_ary_tree_level_order_traversal.py
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a Node.
-class Node:
-    def __init__(self, val, children):
-        self.val = val
-        self.children = children
-"""
-class Solution:
-    def levelOrder(self, root: 'Node') -> List[List[int]]:
-        
\ No newline at end of file
diff --git a/problems/n-ary-tree-level-order-traversal/n_ary_tree_level_order_traversal_test.go b/problems/n-ary-tree-level-order-traversal/n_ary_tree_level_order_traversal_test.go
deleted file mode 100644
index 2b84bcaab..000000000
--- a/problems/n-ary-tree-level-order-traversal/n_ary_tree_level_order_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem429
diff --git a/problems/n-ary-tree-postorder-traversal/README.md b/problems/n-ary-tree-postorder-traversal/README.md
deleted file mode 100644
index 3e107347d..000000000
--- a/problems/n-ary-tree-postorder-traversal/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../n-ary-tree-preorder-traversal "N-ary Tree Preorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../tag-validator "Tag Validator")
-
-## [590. N-ary Tree Postorder Traversal (Easy)](https://leetcode.com/problems/n-ary-tree-postorder-traversal "N 叉树的后序遍历")
-
-<p>Given the <code>root</code> of an n-ary tree, return <em>the postorder traversal of its nodes&#39; values</em>.</p>
-
-<p>Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples)</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://assets.leetcode.com/uploads/2018/10/12/narytreeexample.png" style="width: 100%; max-width: 300px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,3,2,4,null,5,6]
-<strong>Output:</strong> [5,6,3,2,4,1]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/08/sample_4_964.png" style="width: 296px; height: 241px;" />
-<pre>
-<strong>Input:</strong> root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
-<strong>Output:</strong> [2,6,14,11,7,3,12,8,4,13,9,10,5,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-	<li>The height of the n-ary tree is less than or equal to <code>1000</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Recursive solution is trivial, could you do it iteratively?</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Postorder Traversal](../binary-tree-postorder-traversal) (Easy)
-  1. [N-ary Tree Level Order Traversal](../n-ary-tree-level-order-traversal) (Medium)
-  1. [N-ary Tree Preorder Traversal](../n-ary-tree-preorder-traversal) (Easy)
diff --git a/problems/n-ary-tree-postorder-traversal/n_ary_tree_postorder_traversal.go b/problems/n-ary-tree-postorder-traversal/n_ary_tree_postorder_traversal.go
deleted file mode 100644
index bb41768d4..000000000
--- a/problems/n-ary-tree-postorder-traversal/n_ary_tree_postorder_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem590
diff --git a/problems/n-ary-tree-postorder-traversal/n_ary_tree_postorder_traversal.py b/problems/n-ary-tree-postorder-traversal/n_ary_tree_postorder_traversal.py
deleted file mode 100755
index 55281d130..000000000
--- a/problems/n-ary-tree-postorder-traversal/n_ary_tree_postorder_traversal.py
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a Node.
-class Node:
-    def __init__(self, val, children):
-        self.val = val
-        self.children = children
-"""
-class Solution:
-    def postorder(self, root: 'Node') -> List[int]:
-        
\ No newline at end of file
diff --git a/problems/n-ary-tree-postorder-traversal/n_ary_tree_postorder_traversal_test.go b/problems/n-ary-tree-postorder-traversal/n_ary_tree_postorder_traversal_test.go
deleted file mode 100644
index bb41768d4..000000000
--- a/problems/n-ary-tree-postorder-traversal/n_ary_tree_postorder_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem590
diff --git a/problems/n-ary-tree-preorder-traversal/README.md b/problems/n-ary-tree-preorder-traversal/README.md
deleted file mode 100644
index 94fc226d9..000000000
--- a/problems/n-ary-tree-preorder-traversal/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-in-memory-file-system "Design In-Memory File System")
-　　　　　　　　　　　　　　　　
-[Next >](../n-ary-tree-postorder-traversal "N-ary Tree Postorder Traversal")
-
-## [589. N-ary Tree Preorder Traversal (Easy)](https://leetcode.com/problems/n-ary-tree-preorder-traversal "N 叉树的前序遍历")
-
-<p>Given the <code>root</code> of an n-ary tree, return <em>the preorder traversal of its nodes&#39; values</em>.</p>
-
-<p>Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples)</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img src="https://assets.leetcode.com/uploads/2018/10/12/narytreeexample.png" style="width: 100%; max-width: 300px;" /></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,3,2,4,null,5,6]
-<strong>Output:</strong> [1,3,5,6,2,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/11/08/sample_4_964.png" style="width: 296px; height: 241px;" /></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
-<strong>Output:</strong> [1,2,3,6,7,11,14,4,8,12,5,9,13,10]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-	<li>The height of the n-ary tree is less than or equal to <code>1000</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Recursive solution is trivial, could you do it iteratively?</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Preorder Traversal](../binary-tree-preorder-traversal) (Easy)
-  1. [N-ary Tree Level Order Traversal](../n-ary-tree-level-order-traversal) (Medium)
-  1. [N-ary Tree Postorder Traversal](../n-ary-tree-postorder-traversal) (Easy)
diff --git a/problems/n-ary-tree-preorder-traversal/n_ary_tree_preorder_traversal.go b/problems/n-ary-tree-preorder-traversal/n_ary_tree_preorder_traversal.go
deleted file mode 100644
index 74fcff50a..000000000
--- a/problems/n-ary-tree-preorder-traversal/n_ary_tree_preorder_traversal.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem589
diff --git a/problems/n-ary-tree-preorder-traversal/n_ary_tree_preorder_traversal.py b/problems/n-ary-tree-preorder-traversal/n_ary_tree_preorder_traversal.py
deleted file mode 100755
index b0718c6af..000000000
--- a/problems/n-ary-tree-preorder-traversal/n_ary_tree_preorder_traversal.py
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a Node.
-class Node:
-    def __init__(self, val, children):
-        self.val = val
-        self.children = children
-"""
-class Solution:
-    def preorder(self, root: 'Node') -> List[int]:
-        
\ No newline at end of file
diff --git a/problems/n-ary-tree-preorder-traversal/n_ary_tree_preorder_traversal_test.go b/problems/n-ary-tree-preorder-traversal/n_ary_tree_preorder_traversal_test.go
deleted file mode 100644
index 74fcff50a..000000000
--- a/problems/n-ary-tree-preorder-traversal/n_ary_tree_preorder_traversal_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem589
diff --git a/problems/n-queens-ii/README.md b/problems/n-queens-ii/README.md
deleted file mode 100644
index 199e724f3..000000000
--- a/problems/n-queens-ii/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../n-queens "N-Queens")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-subarray "Maximum Subarray")
-
-## [52. N-Queens II (Hard)](https://leetcode.com/problems/n-queens-ii "N皇后 II")
-
-<p>The <strong>n-queens</strong> puzzle is the problem of placing <code>n</code> queens on an <code>n x n</code> chessboard such that no two queens attack each other.</p>
-
-<p>Given an integer <code>n</code>, return <em>the number of distinct solutions to the&nbsp;<strong>n-queens puzzle</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/queens.jpg" style="width: 600px; height: 268px;" />
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are two distinct solutions to the 4-queens puzzle as shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [N-Queens](../n-queens) (Hard)
diff --git a/problems/n-queens-ii/n_queens_ii.go b/problems/n-queens-ii/n_queens_ii.go
deleted file mode 100644
index 56c8d810b..000000000
--- a/problems/n-queens-ii/n_queens_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem52
diff --git a/problems/n-queens-ii/n_queens_ii_test.go b/problems/n-queens-ii/n_queens_ii_test.go
deleted file mode 100644
index 56c8d810b..000000000
--- a/problems/n-queens-ii/n_queens_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem52
diff --git a/problems/n-queens/README.md b/problems/n-queens/README.md
deleted file mode 100644
index 866757347..000000000
--- a/problems/n-queens/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../powx-n "Pow(x, n)")
-　　　　　　　　　　　　　　　　
-[Next >](../n-queens-ii "N-Queens II")
-
-## [51. N-Queens (Hard)](https://leetcode.com/problems/n-queens "N 皇后")
-
-<p>The <strong>n-queens</strong> puzzle is the problem of placing <code>n</code> queens on an <code>n x n</code> chessboard such that no two queens attack each other.</p>
-
-<p>Given an integer <code>n</code>, return <em>all distinct solutions to the <strong>n-queens puzzle</strong></em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>Each solution contains a distinct board configuration of the n-queens&#39; placement, where <code>&#39;Q&#39;</code> and <code>&#39;.&#39;</code> both indicate a queen and an empty space, respectively.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/queens.jpg" style="width: 600px; height: 268px;" />
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> [[&quot;.Q..&quot;,&quot;...Q&quot;,&quot;Q...&quot;,&quot;..Q.&quot;],[&quot;..Q.&quot;,&quot;Q...&quot;,&quot;...Q&quot;,&quot;.Q..&quot;]]
-<strong>Explanation:</strong> There exist two distinct solutions to the 4-queens puzzle as shown above
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> [[&quot;Q&quot;]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [N-Queens II](../n-queens-ii) (Hard)
-  1. [Grid Illumination](../grid-illumination) (Hard)
diff --git a/problems/n-queens/n_queens.go b/problems/n-queens/n_queens.go
deleted file mode 100644
index edb73ff83..000000000
--- a/problems/n-queens/n_queens.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem51
diff --git a/problems/n-queens/n_queens_test.go b/problems/n-queens/n_queens_test.go
deleted file mode 100644
index edb73ff83..000000000
--- a/problems/n-queens/n_queens_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem51
diff --git a/problems/n-repeated-element-in-size-2n-array/README.md b/problems/n-repeated-element-in-size-2n-array/README.md
deleted file mode 100644
index 314994e4f..000000000
--- a/problems/n-repeated-element-in-size-2n-array/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-columns-to-make-sorted-iii "Delete Columns to Make Sorted III")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-width-ramp "Maximum Width Ramp")
-
-## [961. N-Repeated Element in Size 2N Array (Easy)](https://leetcode.com/problems/n-repeated-element-in-size-2n-array "重复 N 次的元素")
-
-<p>You are given an integer array <code>nums</code> with the following properties:</p>
-
-<ul>
-	<li><code>nums.length == 2 * n</code>.</li>
-	<li><code>nums</code> contains <code>n + 1</code> <strong>unique</strong> elements.</li>
-	<li>Exactly one element of <code>nums</code> is repeated <code>n</code> times.</li>
-</ul>
-
-<p>Return <em>the element that is repeated </em><code>n</code><em> times</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3,3]
-<strong>Output:</strong> 3
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [2,1,2,5,3,2]
-<strong>Output:</strong> 2
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [5,1,5,2,5,3,5,4]
-<strong>Output:</strong> 5
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 5000</code></li>
-	<li><code>nums.length == 2 * n</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>nums</code> contains <code>n + 1</code> <strong>unique</strong> elements and one of them is repeated exactly <code>n</code> times.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
diff --git a/problems/n-repeated-element-in-size-2n-array/n_repeated_element_in_size_2n_array.go b/problems/n-repeated-element-in-size-2n-array/n_repeated_element_in_size_2n_array.go
deleted file mode 100644
index 18fa4b5c7..000000000
--- a/problems/n-repeated-element-in-size-2n-array/n_repeated_element_in_size_2n_array.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem961
-
-func repeatedNTimes(A []int) int {
-	m := make(map[int]bool)
-	for _, v := range A {
-		if m[v] {
-			return v
-		}
-		m[v] = true
-	}
-	return 0
-}
diff --git a/problems/n-repeated-element-in-size-2n-array/n_repeated_element_in_size_2n_array_test.go b/problems/n-repeated-element-in-size-2n-array/n_repeated_element_in_size_2n_array_test.go
deleted file mode 100644
index 5c0aa5bed..000000000
--- a/problems/n-repeated-element-in-size-2n-array/n_repeated_element_in_size_2n_array_test.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package problem961
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestRepeatedNTimes(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3, 3},
-			want: 3,
-		},
-		{
-			in:   []int{2, 1, 2, 5, 3, 2},
-			want: 2,
-		},
-		{
-			in:   []int{5, 1, 5, 2, 5, 3, 5, 4},
-			want: 5,
-		},
-		{
-			in:   []int{1, 2, 3},
-			want: 0,
-		},
-	}
-
-	for _, tt := range tests {
-		got := repeatedNTimes(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/n-th-tribonacci-number/README.md b/problems/n-th-tribonacci-number/README.md
deleted file mode 100644
index aad681a58..000000000
--- a/problems/n-th-tribonacci-number/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../parallel-courses "Parallel Courses")
-　　　　　　　　　　　　　　　　
-[Next >](../alphabet-board-path "Alphabet Board Path")
-
-## [1137. N-th Tribonacci Number (Easy)](https://leetcode.com/problems/n-th-tribonacci-number "第 N 个泰波那契数")
-
-<p>The Tribonacci sequence T<sub>n</sub> is defined as follows:&nbsp;</p>
-
-<p>T<sub>0</sub> = 0, T<sub>1</sub> = 1, T<sub>2</sub> = 1, and T<sub>n+3</sub> = T<sub>n</sub> + T<sub>n+1</sub> + T<sub>n+2</sub> for n &gt;= 0.</p>
-
-<p>Given <code>n</code>, return the value of T<sub>n</sub>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-T_3 = 0 + 1 + 1 = 2
-T_4 = 1 + 1 + 2 = 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 25
-<strong>Output:</strong> 1389537
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 37</code></li>
-	<li>The answer is guaranteed to fit within a 32-bit integer, ie. <code>answer &lt;= 2^31 - 1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Climbing Stairs](../climbing-stairs) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Make an array F of length 38, and set F[0] = 0, F[1] = F[2] = 1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Now write a loop where you set F[n+3] = F[n] + F[n+1] + F[n+2], and return F[n].
-</details>
diff --git a/problems/nearest-exit-from-entrance-in-maze/README.md b/problems/nearest-exit-from-entrance-in-maze/README.md
deleted file mode 100644
index 3f05dc6b0..000000000
--- a/problems/nearest-exit-from-entrance-in-maze/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-square-sum-triples "Count Square Sum Triples")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-game "Sum Game")
-
-## [1926. Nearest Exit from Entrance in Maze (Medium)](https://leetcode.com/problems/nearest-exit-from-entrance-in-maze "迷宫中离入口最近的出口")
-
-<p>You are given an <code>m x n</code> matrix <code>maze</code> (<strong>0-indexed</strong>) with empty cells (represented as <code>&#39;.&#39;</code>) and walls (represented as <code>&#39;+&#39;</code>). You are also given the <code>entrance</code> of the maze, where <code>entrance = [entrance<sub>row</sub>, entrance<sub>col</sub>]</code> denotes the row and column of the cell you are initially standing at.</p>
-
-<p>In one step, you can move one cell <strong>up</strong>, <strong>down</strong>, <strong>left</strong>, or <strong>right</strong>. You cannot step into a cell with a wall, and you cannot step outside the maze. Your goal is to find the <strong>nearest exit</strong> from the <code>entrance</code>. An <strong>exit</strong> is defined as an <strong>empty cell</strong> that is at the <strong>border</strong> of the <code>maze</code>. The <code>entrance</code> <strong>does not count</strong> as an exit.</p>
-
-<p>Return <em>the <strong>number of steps</strong> in the shortest path from the </em><code>entrance</code><em> to the nearest exit, or </em><code>-1</code><em> if no such path exists</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/04/nearest1-grid.jpg" style="width: 333px; height: 253px;" />
-<pre>
-<strong>Input:</strong> maze = [[&quot;+&quot;,&quot;+&quot;,&quot;.&quot;,&quot;+&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;+&quot;],[&quot;+&quot;,&quot;+&quot;,&quot;+&quot;,&quot;.&quot;]], entrance = [1,2]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There are 3 exits in this maze at [1,0], [0,2], and [2,3].
-Initially, you are at the entrance cell [1,2].
-- You can reach [1,0] by moving 2 steps left.
-- You can reach [0,2] by moving 1 step up.
-It is impossible to reach [2,3] from the entrance.
-Thus, the nearest exit is [0,2], which is 1 step away.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/04/nearesr2-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> maze = [[&quot;+&quot;,&quot;+&quot;,&quot;+&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;+&quot;,&quot;+&quot;,&quot;+&quot;]], entrance = [1,0]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There is 1 exit in this maze at [1,2].
-[1,0] does not count as an exit since it is the entrance cell.
-Initially, you are at the entrance cell [1,0].
-- You can reach [1,2] by moving 2 steps right.
-Thus, the nearest exit is [1,2], which is 2 steps away.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/04/nearest3-grid.jpg" style="width: 173px; height: 93px;" />
-<pre>
-<strong>Input:</strong> maze = [[&quot;.&quot;,&quot;+&quot;]], entrance = [0,0]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There are no exits in this maze.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>maze.length == m</code></li>
-	<li><code>maze[i].length == n</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li><code>maze[i][j]</code> is either <code>&#39;.&#39;</code> or <code>&#39;+&#39;</code>.</li>
-	<li><code>entrance.length == 2</code></li>
-	<li><code>0 &lt;= entrance<sub>row</sub> &lt; m</code></li>
-	<li><code>0 &lt;= entrance<sub>col</sub> &lt; n</code></li>
-	<li><code>entrance</code> will always be an empty cell.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Which type of traversal lets you find the distance from a point?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try using a Breadth First Search.
-</details>
diff --git a/problems/nested-list-weight-sum-ii/README.md b/problems/nested-list-weight-sum-ii/README.md
deleted file mode 100644
index 3dd813ef7..000000000
--- a/problems/nested-list-weight-sum-ii/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-sum-of-rectangle-no-larger-than-k "Max Sum of Rectangle No Larger Than K")
-　　　　　　　　　　　　　　　　
-[Next >](../water-and-jug-problem "Water and Jug Problem")
-
-## [364. Nested List Weight Sum II (Medium)](https://leetcode.com/problems/nested-list-weight-sum-ii "加权嵌套序列和 II")
-
-<p>Given a nested list of integers, return the sum of all integers in the list weighted by their depth.</p>
-
-<p>Each element is either an integer, or a list -- whose elements may also be integers or other lists.</p>
-
-<p>Different from the <a href="https://leetcode.com/problems/nested-list-weight-sum/">previous question</a> where weight is increasing from root to leaf, now the weight is defined from bottom up. i.e., the leaf level integers have weight 1, and the root level integers have the largest weight.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<div>
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[[1,1],2,[1,1]]</span>
-<strong>Output: </strong><span id="example-output-1">8 
-<strong>Explanation: </strong>F</span>our 1&#39;s at depth 1, one 2 at depth 2.
-</pre>
-
-<div>
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">[1,[4,[6]]]</span>
-<strong>Output: </strong><span id="example-output-2">17 
-<strong>Explanation:</strong> O</span>ne 1 at depth 3, one 4 at depth 2, and one 6 at depth 1; 1*3 + 4*2 + 6*1 = 17.
-</pre>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Nested List Weight Sum](../nested-list-weight-sum) (Medium)
-  1. [Array Nesting](../array-nesting) (Medium)
diff --git a/problems/nested-list-weight-sum-ii/nested_list_weight_sum_ii.go b/problems/nested-list-weight-sum-ii/nested_list_weight_sum_ii.go
deleted file mode 100644
index e06dafdd3..000000000
--- a/problems/nested-list-weight-sum-ii/nested_list_weight_sum_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem364
diff --git a/problems/nested-list-weight-sum-ii/nested_list_weight_sum_ii_test.go b/problems/nested-list-weight-sum-ii/nested_list_weight_sum_ii_test.go
deleted file mode 100644
index e06dafdd3..000000000
--- a/problems/nested-list-weight-sum-ii/nested_list_weight_sum_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem364
diff --git a/problems/nested-list-weight-sum/README.md b/problems/nested-list-weight-sum/README.md
deleted file mode 100644
index 68ee743ea..000000000
--- a/problems/nested-list-weight-sum/README.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../counting-bits "Counting Bits")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-substring-with-at-most-k-distinct-characters "Longest Substring with At Most K Distinct Characters")
-
-## [339. Nested List Weight Sum (Medium)](https://leetcode.com/problems/nested-list-weight-sum "嵌套列表权重和")
-
-<p>Given a nested list of integers, return the sum of all integers in the list weighted by their depth.</p>
-
-<p>Each element is either an integer, or a list -- whose elements may also be integers or other lists.</p>
-
-<div>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[[1,1],2,[1,1]]</span>
-<strong>Output: </strong><span id="example-output-1">10 </span>
-<strong>Explanation: </strong>Four 1&#39;s at depth 2, one 2 at depth 1.</pre>
-
-<div>
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">[1,[4,[6]]]</span>
-<strong>Output: </strong><span id="example-output-2">27 </span>
-<strong>Explanation: </strong>One 1 at depth 1, one 4 at depth 2, and one 6 at depth 3; 1 + 4*2 + 6*3 = 27.</pre>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Nested List Weight Sum II](../nested-list-weight-sum-ii) (Medium)
-  1. [Array Nesting](../array-nesting) (Medium)
-  1. [Employee Importance](../employee-importance) (Medium)
diff --git a/problems/nested-list-weight-sum/nested_list_weight_sum.go b/problems/nested-list-weight-sum/nested_list_weight_sum.go
deleted file mode 100644
index cc87e8d07..000000000
--- a/problems/nested-list-weight-sum/nested_list_weight_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem339
diff --git a/problems/nested-list-weight-sum/nested_list_weight_sum_test.go b/problems/nested-list-weight-sum/nested_list_weight_sum_test.go
deleted file mode 100644
index cc87e8d07..000000000
--- a/problems/nested-list-weight-sum/nested_list_weight_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem339
diff --git a/problems/network-delay-time/README.md b/problems/network-delay-time/README.md
deleted file mode 100644
index 92e5036af..000000000
--- a/problems/network-delay-time/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../closest-leaf-in-a-binary-tree "Closest Leaf in a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../find-smallest-letter-greater-than-target "Find Smallest Letter Greater Than Target")
-
-## [743. Network Delay Time (Medium)](https://leetcode.com/problems/network-delay-time "网络延迟时间")
-
-<p>You are given a network of <code>n</code> nodes, labeled from <code>1</code> to <code>n</code>. You are also given <code>times</code>, a list of travel times as directed edges <code>times[i] = (u<sub>i</sub>, v<sub>i</sub>, w<sub>i</sub>)</code>, where <code>u<sub>i</sub></code> is the source node, <code>v<sub>i</sub></code> is the target node, and <code>w<sub>i</sub></code> is the time it takes for a signal to travel from source to target.</p>
-
-<p>We will send a signal from a given node <code>k</code>. Return the time it takes for all the <code>n</code> nodes to receive the signal. If it is impossible for all the <code>n</code> nodes to receive the signal, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/05/23/931_example_1.png" style="width: 217px; height: 239px;" />
-<pre>
-<strong>Input:</strong> times = [[2,1,1],[2,3,1],[3,4,1]], n = 4, k = 2
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> times = [[1,2,1]], n = 2, k = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> times = [[1,2,1]], n = 2, k = 2
-<strong>Output:</strong> -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= times.length &lt;= 6000</code></li>
-	<li><code>times[i].length == 3</code></li>
-	<li><code>1 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n</code></li>
-	<li><code>u<sub>i</sub> != v<sub>i</sub></code></li>
-	<li><code>0 &lt;= w<sub>i</sub> &lt;= 100</code></li>
-	<li>All the pairs <code>(u<sub>i</sub>, v<sub>i</sub>)</code> are <strong>unique</strong>. (i.e., no multiple edges.)</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We visit each node at some time, and if that time is better than the fastest time we've reached this node, we travel along outgoing edges in sorted order.  Alternatively, we could use Dijkstra's algorithm.
-</details>
diff --git a/problems/network-delay-time/network_delay_time.go b/problems/network-delay-time/network_delay_time.go
deleted file mode 100644
index cb1b0979f..000000000
--- a/problems/network-delay-time/network_delay_time.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem743
diff --git a/problems/network-delay-time/network_delay_time_test.go b/problems/network-delay-time/network_delay_time_test.go
deleted file mode 100644
index cb1b0979f..000000000
--- a/problems/network-delay-time/network_delay_time_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem743
diff --git a/problems/new-21-game/README.md b/problems/new-21-game/README.md
deleted file mode 100644
index 71e615e07..000000000
--- a/problems/new-21-game/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rectangle-overlap "Rectangle Overlap")
-　　　　　　　　　　　　　　　　
-[Next >](../push-dominoes "Push Dominoes")
-
-## [837. New 21 Game (Medium)](https://leetcode.com/problems/new-21-game "新 21 点")
-
-<p>Alice plays the following game, loosely based on the card game <strong>&quot;21&quot;</strong>.</p>
-
-<p>Alice starts with <code>0</code> points and draws numbers while she has less than <code>k</code> points. During each draw, she gains an integer number of points randomly from the range <code>[1, maxPts]</code>, where <code>maxPts</code> is an integer. Each draw is independent and the outcomes have equal probabilities.</p>
-
-<p>Alice stops drawing numbers when she gets <code>k</code> <strong>or more points</strong>.</p>
-
-<p>Return the probability that Alice has <code>n</code> or fewer points.</p>
-
-<p>Answers within <code>10<sup>-5</sup></code> of the actual answer are considered accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10, k = 1, maxPts = 10
-<strong>Output:</strong> 1.00000
-<strong>Explanation:</strong> Alice gets a single card, then stops.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6, k = 1, maxPts = 10
-<strong>Output:</strong> 0.60000
-<strong>Explanation:</strong> Alice gets a single card, then stops.
-In 6 out of 10 possibilities, she is at or below 6 points.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 21, k = 17, maxPts = 10
-<strong>Output:</strong> 0.73278
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= k &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= maxPts &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Probability and Statistics](../../tag/probability-and-statistics/README.md)]
diff --git a/problems/new-21-game/new_21_game.go b/problems/new-21-game/new_21_game.go
deleted file mode 100644
index 46760f4f4..000000000
--- a/problems/new-21-game/new_21_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem837
diff --git a/problems/new-21-game/new_21_game_test.go b/problems/new-21-game/new_21_game_test.go
deleted file mode 100644
index 46760f4f4..000000000
--- a/problems/new-21-game/new_21_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem837
diff --git a/problems/new-users-daily-count/README.md b/problems/new-users-daily-count/README.md
deleted file mode 100644
index 76f4e50e6..000000000
--- a/problems/new-users-daily-count/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../parsing-a-boolean-expression "Parsing A Boolean Expression")
-　　　　　　　　　　　　　　　　
-[Next >](../defanging-an-ip-address "Defanging an IP Address")
-
-## [1107. New Users Daily Count (Medium)](https://leetcode.com/problems/new-users-daily-count "每日新用户统计")
-
-<p>Table: <code>Traffic</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| user_id       | int     |
-| activity      | enum    |
-| activity_date | date    |
-+---------------+---------+
-There is no primary key for this table, it may have duplicate rows.
-The activity column is an ENUM type of (&#39;login&#39;, &#39;logout&#39;, &#39;jobs&#39;, &#39;groups&#39;, &#39;homepage&#39;).
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports for every date within at most&nbsp;<strong>90 days</strong> from today, the number of users that logged in for the first time on that date. Assume today is <strong>2019-06-30</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Traffic table:
-+---------+----------+---------------+
-| user_id | activity | activity_date |
-+---------+----------+---------------+
-| 1       | login    | 2019-05-01    |
-| 1       | homepage | 2019-05-01    |
-| 1       | logout   | 2019-05-01    |
-| 2       | login    | 2019-06-21    |
-| 2       | logout   | 2019-06-21    |
-| 3       | login    | 2019-01-01    |
-| 3       | jobs     | 2019-01-01    |
-| 3       | logout   | 2019-01-01    |
-| 4       | login    | 2019-06-21    |
-| 4       | groups   | 2019-06-21    |
-| 4       | logout   | 2019-06-21    |
-| 5       | login    | 2019-03-01    |
-| 5       | logout   | 2019-03-01    |
-| 5       | login    | 2019-06-21    |
-| 5       | logout   | 2019-06-21    |
-+---------+----------+---------------+
-
-Result table:
-+------------+-------------+
-| login_date | user_count  |
-+------------+-------------+
-| 2019-05-01 | 1           |
-| 2019-06-21 | 2           |
-+------------+-------------+
-Note that we only care about dates with non zero user count.
-The user with id 5 first logged in on 2019-03-01 so he&#39;s not counted on 2019-06-21.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/new-users-daily-count/mysql_schemas.sql b/problems/new-users-daily-count/mysql_schemas.sql
deleted file mode 100644
index 9ac0aadcd..000000000
--- a/problems/new-users-daily-count/mysql_schemas.sql
+++ /dev/null
@@ -1,17 +0,0 @@
-Create table If Not Exists Traffic (user_id int, activity ENUM('login', 'logout', 'jobs', 'groups', 'homepage'), activity_date date);
-Truncate table Traffic;
-insert into Traffic (user_id, activity, activity_date) values ('1', 'login', '2019-05-01');
-insert into Traffic (user_id, activity, activity_date) values ('1', 'homepage', '2019-05-01');
-insert into Traffic (user_id, activity, activity_date) values ('1', 'logout', '2019-05-01');
-insert into Traffic (user_id, activity, activity_date) values ('2', 'login', '2019-06-21');
-insert into Traffic (user_id, activity, activity_date) values ('2', 'logout', '2019-06-21');
-insert into Traffic (user_id, activity, activity_date) values ('3', 'login', '2019-01-01');
-insert into Traffic (user_id, activity, activity_date) values ('3', 'jobs', '2019-01-01');
-insert into Traffic (user_id, activity, activity_date) values ('3', 'logout', '2019-01-01');
-insert into Traffic (user_id, activity, activity_date) values ('4', 'login', '2019-06-21');
-insert into Traffic (user_id, activity, activity_date) values ('4', 'groups', '2019-06-21');
-insert into Traffic (user_id, activity, activity_date) values ('4', 'logout', '2019-06-21');
-insert into Traffic (user_id, activity, activity_date) values ('5', 'login', '2019-03-01');
-insert into Traffic (user_id, activity, activity_date) values ('5', 'logout', '2019-03-01');
-insert into Traffic (user_id, activity, activity_date) values ('5', 'login', '2019-06-21');
-insert into Traffic (user_id, activity, activity_date) values ('5', 'logout', '2019-06-21');
diff --git a/problems/new-users-daily-count/new_users_daily_count.sql b/problems/new-users-daily-count/new_users_daily_count.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/new-users-daily-count/new_users_daily_count.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/next-closest-time/README.md b/problems/next-closest-time/README.md
deleted file mode 100644
index 668e17970..000000000
--- a/problems/next-closest-time/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-palindrome-ii "Valid Palindrome II")
-　　　　　　　　　　　　　　　　
-[Next >](../baseball-game "Baseball Game")
-
-## [681. Next Closest Time (Medium)](https://leetcode.com/problems/next-closest-time "最近时刻")
-
-<p>Given a time represented in the format "HH:MM", form the next closest time by reusing the current digits. There is no limit on how many times a digit can be reused.</p>
-
-<p>You may assume the given input string is always valid. For example, "01:34", "12:09" are all valid. "1:34", "12:9" are all invalid.</p>
-
-<p><b>Example 1:</b>
-<pre>
-<b>Input:</b> "19:34"
-<b>Output:</b> "19:39"
-<b>Explanation:</b> The next closest time choosing from digits <b>1</b>, <b>9</b>, <b>3</b>, <b>4</b>, is <b>19:39</b>, which occurs 5 minutes later.  It is not <b>19:33</b>, because this occurs 23 hours and 59 minutes later.
-</pre>
-</p>
-
-<p><b>Example 2:</b>
-<pre>
-<b>Input:</b> "23:59"
-<b>Output:</b> "22:22"
-<b>Explanation:</b> The next closest time choosing from digits <b>2</b>, <b>3</b>, <b>5</b>, <b>9</b>, is <b>22:22</b>. It may be assumed that the returned time is next day's time since it is smaller than the input time numerically.
-</pre>
-</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
diff --git a/problems/next-closest-time/next_closest_time.go b/problems/next-closest-time/next_closest_time.go
deleted file mode 100644
index e66321230..000000000
--- a/problems/next-closest-time/next_closest_time.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem681
diff --git a/problems/next-closest-time/next_closest_time_test.go b/problems/next-closest-time/next_closest_time_test.go
deleted file mode 100644
index e66321230..000000000
--- a/problems/next-closest-time/next_closest_time_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem681
diff --git a/problems/next-greater-element-i/README.md b/problems/next-greater-element-i/README.md
deleted file mode 100644
index 3a5f0dc2f..000000000
--- a/problems/next-greater-element-i/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../teemo-attacking "Teemo Attacking")
-　　　　　　　　　　　　　　　　
-[Next >](../random-point-in-non-overlapping-rectangles "Random Point in Non-overlapping Rectangles")
-
-## [496. Next Greater Element I (Easy)](https://leetcode.com/problems/next-greater-element-i "下一个更大元素 I")
-
-<p>The <strong>next greater element</strong> of some element <code>x</code> in an array is the <strong>first greater</strong> element that is <strong>to the right</strong> of <code>x</code> in the same array.</p>
-
-<p>You are given two <strong>distinct 0-indexed</strong> integer arrays <code>nums1</code> and <code>nums2</code>, where <code>nums1</code> is a subset of <code>nums2</code>.</p>
-
-<p>For each <code>0 &lt;= i &lt; nums1.length</code>, find the index <code>j</code> such that <code>nums1[i] == nums2[j]</code> and determine the <strong>next greater element</strong> of <code>nums2[j]</code> in <code>nums2</code>. If there is no next greater element, then the answer for this query is <code>-1</code>.</p>
-
-<p>Return <em>an array </em><code>ans</code><em> of length </em><code>nums1.length</code><em> such that </em><code>ans[i]</code><em> is the <strong>next greater element</strong> as described above.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [4,1,2], nums2 = [1,3,4,2]
-<strong>Output:</strong> [-1,3,-1]
-<strong>Explanation:</strong> The next greater element for each value of nums1 is as follows:
-- 4 is underlined in nums2 = [1,3,<u>4</u>,2]. There is no next greater element, so the answer is -1.
-- 1 is underlined in nums2 = [<u>1</u>,3,4,2]. The next greater element is 3.
-- 2 is underlined in nums2 = [1,3,4,<u>2</u>]. There is no next greater element, so the answer is -1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [2,4], nums2 = [1,2,3,4]
-<strong>Output:</strong> [3,-1]
-<strong>Explanation:</strong> The next greater element for each value of nums1 is as follows:
-- 2 is underlined in nums2 = [1,<u>2</u>,3,4]. The next greater element is 3.
-- 4 is underlined in nums2 = [1,2,3,<u>4</u>]. There is no next greater element, so the answer is -1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length &lt;= nums2.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums1[i], nums2[i] &lt;= 10<sup>4</sup></code></li>
-	<li>All integers in <code>nums1</code> and <code>nums2</code> are <strong>unique</strong>.</li>
-	<li>All the integers of <code>nums1</code> also appear in <code>nums2</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you find an <code>O(nums1.length + nums2.length)</code> solution?
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Next Greater Element II](../next-greater-element-ii) (Medium)
-  1. [Next Greater Element III](../next-greater-element-iii) (Medium)
-  1. [Daily Temperatures](../daily-temperatures) (Medium)
diff --git a/problems/next-greater-element-i/next_greater_element_i.go b/problems/next-greater-element-i/next_greater_element_i.go
deleted file mode 100644
index 779b93929..000000000
--- a/problems/next-greater-element-i/next_greater_element_i.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem496
diff --git a/problems/next-greater-element-i/next_greater_element_i_test.go b/problems/next-greater-element-i/next_greater_element_i_test.go
deleted file mode 100644
index 779b93929..000000000
--- a/problems/next-greater-element-i/next_greater_element_i_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem496
diff --git a/problems/next-greater-element-ii/README.md b/problems/next-greater-element-ii/README.md
deleted file mode 100644
index 7bcd419b2..000000000
--- a/problems/next-greater-element-ii/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ipo "IPO")
-　　　　　　　　　　　　　　　　
-[Next >](../base-7 "Base 7")
-
-## [503. Next Greater Element II (Medium)](https://leetcode.com/problems/next-greater-element-ii "下一个更大元素 II")
-
-<p>Given a circular integer array <code>nums</code> (i.e., the next element of <code>nums[nums.length - 1]</code> is <code>nums[0]</code>), return <em>the <strong>next greater number</strong> for every element in</em> <code>nums</code>.</p>
-
-<p>The <strong>next greater number</strong> of a number <code>x</code> is the first greater number to its traversing-order next in the array, which means you could search circularly to find its next greater number. If it doesn&#39;t exist, return <code>-1</code> for this number.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1]
-<strong>Output:</strong> [2,-1,2]
-Explanation: The first 1&#39;s next greater number is 2; 
-The number 2 can&#39;t find next greater number. 
-The second 1&#39;s next greater number needs to search circularly, which is also 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,3]
-<strong>Output:</strong> [2,3,4,-1,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Next Greater Element I](../next-greater-element-i) (Easy)
-  1. [Next Greater Element III](../next-greater-element-iii) (Medium)
diff --git a/problems/next-greater-element-ii/next_greater_element_ii.go b/problems/next-greater-element-ii/next_greater_element_ii.go
deleted file mode 100644
index 1057e1687..000000000
--- a/problems/next-greater-element-ii/next_greater_element_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem503
diff --git a/problems/next-greater-element-ii/next_greater_element_ii_test.go b/problems/next-greater-element-ii/next_greater_element_ii_test.go
deleted file mode 100644
index 1057e1687..000000000
--- a/problems/next-greater-element-ii/next_greater_element_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem503
diff --git a/problems/next-greater-element-iii/README.md b/problems/next-greater-element-iii/README.md
deleted file mode 100644
index a5dfc606b..000000000
--- a/problems/next-greater-element-iii/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-concatenated-strings "Split Concatenated Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-words-in-a-string-iii "Reverse Words in a String III")
-
-## [556. Next Greater Element III (Medium)](https://leetcode.com/problems/next-greater-element-iii "下一个更大元素 III")
-
-<p>Given a positive integer <code>n</code>, find <em>the smallest integer which has exactly the same digits existing in the integer</em> <code>n</code> <em>and is greater in value than</em> <code>n</code>. If no such positive integer exists, return <code>-1</code>.</p>
-
-<p><strong>Note</strong> that the returned integer should fit in <strong>32-bit integer</strong>, if there is a valid answer but it does not fit in <strong>32-bit integer</strong>, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 12
-<strong>Output:</strong> 21
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 21
-<strong>Output:</strong> -1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Next Greater Element I](../next-greater-element-i) (Easy)
-  1. [Next Greater Element II](../next-greater-element-ii) (Medium)
diff --git a/problems/next-greater-element-iii/next_greater_element_iii.go b/problems/next-greater-element-iii/next_greater_element_iii.go
deleted file mode 100644
index 4a7201280..000000000
--- a/problems/next-greater-element-iii/next_greater_element_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem556
diff --git a/problems/next-greater-element-iii/next_greater_element_iii_test.go b/problems/next-greater-element-iii/next_greater_element_iii_test.go
deleted file mode 100644
index 4a7201280..000000000
--- a/problems/next-greater-element-iii/next_greater_element_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem556
diff --git a/problems/next-greater-node-in-linked-list/README.md b/problems/next-greater-node-in-linked-list/README.md
deleted file mode 100644
index 89037df98..000000000
--- a/problems/next-greater-node-in-linked-list/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-prefix-divisible-by-5 "Binary Prefix Divisible By 5")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-enclaves "Number of Enclaves")
-
-## [1019. Next Greater Node In Linked List (Medium)](https://leetcode.com/problems/next-greater-node-in-linked-list "链表中的下一个更大节点")
-
-<p>You are given the <code>head</code> of a linked list with <code>n</code> nodes.</p>
-
-<p>For each node in the list, find the value of the <strong>next greater node</strong>. That is, for each node, find the value of the first node that is next to it and has a <strong>strictly larger</strong> value than it.</p>
-
-<p>Return an integer array <code>answer</code> where <code>answer[i]</code> is the value of the next greater node of the <code>i<sup>th</sup></code> node (<strong>1-indexed</strong>). If the <code>i<sup>th</sup></code> node does not have a next greater node, set <code>answer[i] = 0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/05/linkedlistnext1.jpg" style="width: 304px; height: 133px;" />
-<pre>
-<strong>Input:</strong> head = [2,1,5]
-<strong>Output:</strong> [5,5,0]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/05/linkedlistnext2.jpg" style="width: 500px; height: 113px;" />
-<pre>
-<strong>Input:</strong> head = [2,7,4,3,5]
-<strong>Output:</strong> [7,0,5,5,0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is <code>n</code>.</li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can use a stack that stores nodes in monotone decreasing order of value.  When we see a node_j with a larger value, every node_i in the stack has next_larger(node_i) = node_j .
-</details>
diff --git a/problems/next-greater-numerically-balanced-number/README.md b/problems/next-greater-numerically-balanced-number/README.md
deleted file mode 100644
index 338830ba3..000000000
--- a/problems/next-greater-numerically-balanced-number/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-valid-words-in-a-sentence "Number of Valid Words in a Sentence")
-　　　　　　　　　　　　　　　　
-[Next >](../count-nodes-with-the-highest-score "Count Nodes With the Highest Score")
-
-## [2048. Next Greater Numerically Balanced Number (Medium)](https://leetcode.com/problems/next-greater-numerically-balanced-number "下一个更大的数值平衡数")
-
-<p>An integer <code>x</code> is <strong>numerically balanced</strong> if for every digit <code>d</code> in the number <code>x</code>, there are <strong>exactly</strong> <code>d</code> occurrences of that digit in <code>x</code>.</p>
-
-<p>Given an integer <code>n</code>, return <em>the <strong>smallest numerically balanced</strong> number <strong>strictly greater</strong> than </em><code>n</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 22
-<strong>Explanation:</strong> 
-22 is numerically balanced since:
-- The digit 2 occurs 2 times. 
-It is also the smallest numerically balanced number strictly greater than 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1000
-<strong>Output:</strong> 1333
-<strong>Explanation:</strong> 
-1333 is numerically balanced since:
-- The digit 1 occurs 1 time.
-- The digit 3 occurs 3 times. 
-It is also the smallest numerically balanced number strictly greater than 1000.
-Note that 1022 cannot be the answer because 0 appeared more than 0 times.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3000
-<strong>Output:</strong> 3133
-<strong>Explanation:</strong> 
-3133 is numerically balanced since:
-- The digit 1 occurs 1 time.
-- The digit 3 occurs 3 times.
-It is also the smallest numerically balanced number strictly greater than 3000.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How far away can the next greater numerically balanced number be from n?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-With the given constraints, what is the largest numerically balanced number?
-</details>
diff --git a/problems/next-palindrome-using-same-digits/README.md b/problems/next-palindrome-using-same-digits/README.md
deleted file mode 100644
index 5c062380d..000000000
--- a/problems/next-palindrome-using-same-digits/README.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../league-statistics "League Statistics")
-　　　　　　　　　　　　　　　　
-[Next >](../suspicious-bank-accounts "Suspicious Bank Accounts")
-
-## [1842. Next Palindrome Using Same Digits (Hard)](https://leetcode.com/problems/next-palindrome-using-same-digits "下个由相同数字构成的回文串")
-
-
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is it possible to swap one character in the first half of the palindrome to make the next one?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Are there different cases for when the length is odd and even?
-</details>
diff --git a/problems/next-permutation/README.md b/problems/next-permutation/README.md
deleted file mode 100644
index b85f403e3..000000000
--- a/problems/next-permutation/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../substring-with-concatenation-of-all-words "Substring with Concatenation of All Words")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-valid-parentheses "Longest Valid Parentheses")
-
-## [31. Next Permutation (Medium)](https://leetcode.com/problems/next-permutation "下一个排列")
-
-<p>Implement <strong>next permutation</strong>, which rearranges numbers into the lexicographically next greater permutation of numbers.</p>
-
-<p>If such an arrangement is not possible, it must rearrange it as the lowest possible order (i.e., sorted in ascending order).</p>
-
-<p>The replacement must be <strong><a href="http://en.wikipedia.org/wiki/In-place_algorithm" target="_blank">in place</a></strong> and use only constant&nbsp;extra memory.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> [1,3,2]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [3,2,1]
-<strong>Output:</strong> [1,2,3]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1,5]
-<strong>Output:</strong> [1,5,1]
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> nums = [1]
-<strong>Output:</strong> [1]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Permutations](../permutations) (Medium)
-  1. [Permutations II](../permutations-ii) (Medium)
-  1. [Permutation Sequence](../permutation-sequence) (Hard)
-  1. [Palindrome Permutation II](../palindrome-permutation-ii) (Medium)
diff --git a/problems/next-permutation/next_permutation.go b/problems/next-permutation/next_permutation.go
deleted file mode 100644
index 235fecf99..000000000
--- a/problems/next-permutation/next_permutation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem31
diff --git a/problems/next-permutation/next_permutation_test.go b/problems/next-permutation/next_permutation_test.go
deleted file mode 100644
index 235fecf99..000000000
--- a/problems/next-permutation/next_permutation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem31
diff --git a/problems/nim-game/README.md b/problems/nim-game/README.md
deleted file mode 100644
index 263994332..000000000
--- a/problems/nim-game/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-pattern-ii "Word Pattern II")
-　　　　　　　　　　　　　　　　
-[Next >](../flip-game "Flip Game")
-
-## [292. Nim Game (Easy)](https://leetcode.com/problems/nim-game "Nim 游戏")
-
-<p>You are playing the following Nim Game with your friend:</p>
-
-<ul>
-	<li>Initially, there is a heap of stones on the table.</li>
-	<li>You and your friend will alternate taking turns, and <strong>you go first</strong>.</li>
-	<li>On each turn, the person whose turn it is will remove 1 to 3 stones from the heap.</li>
-	<li>The one who removes the last stone is the winner.</li>
-</ul>
-
-<p>Given <code>n</code>, the number of stones in the heap, return <code>true</code><em> if you can win the game assuming both you and your friend play optimally, otherwise return </em><code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> false
-<strong>Explanation:</strong> These are the possible outcomes:
-1. You remove 1 stone. Your friend removes 3 stones, including the last stone. Your friend wins.
-2. You remove 2 stones. Your friend removes 2 stones, including the last stone. Your friend wins.
-3. You remove 3 stones. Your friend removes the last stone. Your friend wins.
-In all outcomes, your friend wins.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Brainteaser](../../tag/brainteaser/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Similar Questions
-  1. [Flip Game II](../flip-game-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If there are 5 stones in the heap, could you figure out a way to remove the stones such that you will always be the winner?
-</details>
diff --git a/problems/nim-game/nim_game.go b/problems/nim-game/nim_game.go
deleted file mode 100644
index ce9563614..000000000
--- a/problems/nim-game/nim_game.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem292
-
-func canWinNim(n int) bool {
-	return n%4 != 0
-}
diff --git a/problems/nim-game/nim_game_test.go b/problems/nim-game/nim_game_test.go
deleted file mode 100644
index acd719a48..000000000
--- a/problems/nim-game/nim_game_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem292
-
-import "testing"
-
-type testType struct {
-	in   int
-	want bool
-}
-
-func TestCanWinNim(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   4,
-			want: false,
-		},
-		{
-			in:   3,
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := canWinNim(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/non-decreasing-array/README.md b/problems/non-decreasing-array/README.md
deleted file mode 100644
index 1bf899059..000000000
--- a/problems/non-decreasing-array/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../strange-printer "Strange Printer")
-　　　　　　　　　　　　　　　　
-[Next >](../path-sum-iv "Path Sum IV")
-
-## [665. Non-decreasing Array (Medium)](https://leetcode.com/problems/non-decreasing-array "非递减数列")
-
-<p>Given an array <code>nums</code> with <code>n</code> integers, your task is to check if it could become non-decreasing by modifying <strong>at most one element</strong>.</p>
-
-<p>We define an array is non-decreasing if <code>nums[i] &lt;= nums[i + 1]</code> holds for every <code>i</code> (<strong>0-based</strong>) such that (<code>0 &lt;= i &lt;= n - 2</code>).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,3]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You could modify the first <code>4</code> to <code>1</code> to get a non-decreasing array.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,1]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> You can&#39;t get a non-decreasing array by modify at most one element.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Find Good Days to Rob the Bank](../find-good-days-to-rob-the-bank) (Medium)
diff --git a/problems/non-decreasing-array/non_decreasing_array.go b/problems/non-decreasing-array/non_decreasing_array.go
deleted file mode 100644
index a60523f4d..000000000
--- a/problems/non-decreasing-array/non_decreasing_array.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem665
-
-func checkPossibility(nums []int) bool {
-	modified := false
-	for i := 0; i < len(nums)-1; i++ {
-		if nums[i] > nums[i+1] {
-			if modified {
-				return false
-			} else if i >= 1 && nums[i-1] > nums[i+1] {
-				nums[i+1] = nums[i]
-			}
-			modified = true
-		}
-	}
-	return true
-}
diff --git a/problems/non-decreasing-array/non_decreasing_array_test.go b/problems/non-decreasing-array/non_decreasing_array_test.go
deleted file mode 100644
index cb03c1529..000000000
--- a/problems/non-decreasing-array/non_decreasing_array_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem665
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestCheckPossibility(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 2, 5},
-			want: true,
-		},
-		{
-			in:   []int{3, 2, 1},
-			want: false,
-		},
-		{
-			in:   []int{3, 4, 2, 3},
-			want: false,
-		},
-		{
-			in:   []int{1, 2, 3, 7, 5, 6},
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 3, 7, 1, 9},
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := checkPossibility(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/non-negative-integers-without-consecutive-ones/README.md b/problems/non-negative-integers-without-consecutive-ones/README.md
deleted file mode 100644
index f91c56fd0..000000000
--- a/problems/non-negative-integers-without-consecutive-ones/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-index-sum-of-two-lists "Minimum Index Sum of Two Lists")
-　　　　　　　　　　　　　　　　
-[Next >](../human-traffic-of-stadium "Human Traffic of Stadium")
-
-## [600. Non-negative Integers without Consecutive Ones (Hard)](https://leetcode.com/problems/non-negative-integers-without-consecutive-ones "不含连续1的非负整数")
-
-<p>Given a positive integer <code>n</code>, return the number of the integers in the range <code>[0, n]</code> whose binary representations <strong>do not</strong> contain consecutive ones.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> 5
-<strong>Explanation:</strong>
-Here are the non-negative integers &lt;= 5 with their corresponding binary representations:
-0 : 0
-1 : 1
-2 : 10
-3 : 11
-4 : 100
-5 : 101
-Among them, only integer 3 disobeys the rule (two consecutive ones) and the other 5 satisfy the rule. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [House Robber](../house-robber) (Medium)
-  1. [House Robber II](../house-robber-ii) (Medium)
-  1. [Ones and Zeroes](../ones-and-zeroes) (Medium)
diff --git a/problems/non-negative-integers-without-consecutive-ones/non_negative_integers_without_consecutive_ones.go b/problems/non-negative-integers-without-consecutive-ones/non_negative_integers_without_consecutive_ones.go
deleted file mode 100644
index fa0037692..000000000
--- a/problems/non-negative-integers-without-consecutive-ones/non_negative_integers_without_consecutive_ones.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem600
diff --git a/problems/non-negative-integers-without-consecutive-ones/non_negative_integers_without_consecutive_ones_test.go b/problems/non-negative-integers-without-consecutive-ones/non_negative_integers_without_consecutive_ones_test.go
deleted file mode 100644
index fa0037692..000000000
--- a/problems/non-negative-integers-without-consecutive-ones/non_negative_integers_without_consecutive_ones_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem600
diff --git a/problems/non-overlapping-intervals/README.md b/problems/non-overlapping-intervals/README.md
deleted file mode 100644
index 87e619f28..000000000
--- a/problems/non-overlapping-intervals/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-segments-in-a-string "Number of Segments in a String")
-　　　　　　　　　　　　　　　　
-[Next >](../find-right-interval "Find Right Interval")
-
-## [435. Non-overlapping Intervals (Medium)](https://leetcode.com/problems/non-overlapping-intervals "无重叠区间")
-
-<p>Given an array of intervals <code>intervals</code> where <code>intervals[i] = [start<sub>i</sub>, end<sub>i</sub>]</code>, return <em>the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,2],[2,3],[3,4],[1,3]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> [1,3] can be removed and the rest of the intervals are non-overlapping.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,2],[1,2],[1,2]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You need to remove two [1,2] to make the rest of the intervals non-overlapping.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,2],[2,3]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> You don&#39;t need to remove any of the intervals since they&#39;re already non-overlapping.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= intervals.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>intervals[i].length == 2</code></li>
-	<li><code>-5 * 10<sup>4</sup> &lt;= start<sub>i</sub> &lt; end<sub>i</sub> &lt;= 5 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Minimum Number of Arrows to Burst Balloons](../minimum-number-of-arrows-to-burst-balloons) (Medium)
diff --git a/problems/non-overlapping-intervals/non_overlapping_intervals.go b/problems/non-overlapping-intervals/non_overlapping_intervals.go
deleted file mode 100644
index 55f061e53..000000000
--- a/problems/non-overlapping-intervals/non_overlapping_intervals.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem435
diff --git a/problems/non-overlapping-intervals/non_overlapping_intervals_test.go b/problems/non-overlapping-intervals/non_overlapping_intervals_test.go
deleted file mode 100644
index 55f061e53..000000000
--- a/problems/non-overlapping-intervals/non_overlapping_intervals_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem435
diff --git a/problems/not-boring-movies/README.md b/problems/not-boring-movies/README.md
deleted file mode 100644
index 98c86a8bc..000000000
--- a/problems/not-boring-movies/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../biggest-single-number "Biggest Single Number")
-　　　　　　　　　　　　　　　　
-[Next >](../task-scheduler "Task Scheduler")
-
-## [620. Not Boring Movies (Easy)](https://leetcode.com/problems/not-boring-movies "有趣的电影")
-
-<p>Table: <code>Cinema</code></p>
-
-<pre>
-+----------------+----------+
-| Column Name    | Type     |
-+----------------+----------+
-| id             | int      |
-| movie          | varchar  |
-| description    | varchar  |
-| rating         | float    |
-+----------------+----------+
-id is the primary key for this table.
-Each row contains information about the name of a movie, its genre, and its rating.
-rating is a 2 decimal places float in the range [0, 10]
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to report the movies with an odd-numbered ID and a description that is not <code>&quot;boring&quot;</code>.</p>
-
-<p>Return the result table ordered by <code>rating</code> <strong>in descending order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Cinema table:
-+----+------------+-------------+--------+
-| id | movie      | description | rating |
-+----+------------+-------------+--------+
-| 1  | War        | great 3D    | 8.9    |
-| 2  | Science    | fiction     | 8.5    |
-| 3  | irish      | boring      | 6.2    |
-| 4  | Ice song   | Fantacy     | 8.6    |
-| 5  | House card | Interesting | 9.1    |
-+----+------------+-------------+--------+
-<strong>Output:</strong> 
-+----+------------+-------------+--------+
-| id | movie      | description | rating |
-+----+------------+-------------+--------+
-| 5  | House card | Interesting | 9.1    |
-| 1  | War        | great 3D    | 8.9    |
-+----+------------+-------------+--------+
-<strong>Explanation:</strong> 
-We have three movies with odd-numbered IDs: 1, 3, and 5. The movie with ID = 3 is boring so we do not include it in the answer.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/not-boring-movies/mysql_schemas.sql b/problems/not-boring-movies/mysql_schemas.sql
deleted file mode 100644
index 51a9eae8a..000000000
--- a/problems/not-boring-movies/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists cinema (id int, movie varchar(255), description varchar(255), rating float(2, 1));
-Truncate table cinema;
-insert into cinema (id, movie, description, rating) values ('1', 'War', 'great 3D', '8.9');
-insert into cinema (id, movie, description, rating) values ('2', 'Science', 'fiction', '8.5');
-insert into cinema (id, movie, description, rating) values ('3', 'irish', 'boring', '6.2');
-insert into cinema (id, movie, description, rating) values ('4', 'Ice song', 'Fantacy', '8.6');
-insert into cinema (id, movie, description, rating) values ('5', 'House card', 'Interesting', '9.1');
diff --git a/problems/not-boring-movies/not_boring_movies.sql b/problems/not-boring-movies/not_boring_movies.sql
deleted file mode 100644
index 97f268428..000000000
--- a/problems/not-boring-movies/not_boring_movies.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT *
-FROM
-  cinema
-WHERE
-  MOD(id, 2) = 1
-  AND description != 'boring'
-ORDER BY
-  rating DESC;
diff --git a/problems/npv-queries/README.md b/problems/npv-queries/README.md
deleted file mode 100644
index 70c027462..000000000
--- a/problems/npv-queries/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../build-array-where-you-can-find-the-maximum-exactly-k-comparisons "Build Array Where You Can Find The Maximum Exactly K Comparisons")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-score-after-splitting-a-string "Maximum Score After Splitting a String")
-
-## [1421. NPV Queries (Medium)](https://leetcode.com/problems/npv-queries "净现值查询")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/npv-queries/mysql_schemas.sql b/problems/npv-queries/mysql_schemas.sql
deleted file mode 100644
index 0ad1de8aa..000000000
--- a/problems/npv-queries/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create Table If Not Exists NPV (id int, year int, npv int);
-Create Table If Not Exists Queries (id int, year int);
-Truncate table NPV;
-insert into NPV (id, year, npv) values ('1', '2018', '100');
-insert into NPV (id, year, npv) values ('7', '2020', '30');
-insert into NPV (id, year, npv) values ('13', '2019', '40');
-insert into NPV (id, year, npv) values ('1', '2019', '113');
-insert into NPV (id, year, npv) values ('2', '2008', '121');
-insert into NPV (id, year, npv) values ('3', '2009', '21');
-insert into NPV (id, year, npv) values ('11', '2020', '99');
-insert into NPV (id, year, npv) values ('7', '2019', '0');
-Truncate table Queries;
-insert into Queries (id, year) values ('1', '2019');
-insert into Queries (id, year) values ('2', '2008');
-insert into Queries (id, year) values ('3', '2009');
-insert into Queries (id, year) values ('7', '2018');
-insert into Queries (id, year) values ('7', '2019');
-insert into Queries (id, year) values ('7', '2020');
-insert into Queries (id, year) values ('13', '2019');
diff --git a/problems/nth-digit/README.md b/problems/nth-digit/README.md
deleted file mode 100644
index b2130eefe..000000000
--- a/problems/nth-digit/README.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../evaluate-division "Evaluate Division")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-watch "Binary Watch")
-
-## [400. Nth Digit (Medium)](https://leetcode.com/problems/nth-digit "第 N 位数字")
-
-<p>Given an integer <code>n</code>, return the <code>n<sup>th</sup></code> digit of the infinite integer sequence <code>[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 11
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The 11<sup>th</sup> digit of the sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ... is a 0, which is part of the number 10.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
diff --git a/problems/nth-digit/nth_digit.go b/problems/nth-digit/nth_digit.go
deleted file mode 100644
index c440da197..000000000
--- a/problems/nth-digit/nth_digit.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem400
diff --git a/problems/nth-digit/nth_digit_test.go b/problems/nth-digit/nth_digit_test.go
deleted file mode 100644
index c440da197..000000000
--- a/problems/nth-digit/nth_digit_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem400
diff --git a/problems/nth-highest-salary/README.md b/problems/nth-highest-salary/README.md
deleted file mode 100644
index b810c5eca..000000000
--- a/problems/nth-highest-salary/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../second-highest-salary "Second Highest Salary")
-　　　　　　　　　　　　　　　　
-[Next >](../rank-scores "Rank Scores")
-
-## [177. Nth Highest Salary (Medium)](https://leetcode.com/problems/nth-highest-salary "第N高的薪水")
-
-<p>Table: <code>Employee</code></p>
-
-<pre>
-+-------------+------+
-| Column Name | Type |
-+-------------+------+
-| id          | int  |
-| salary      | int  |
-+-------------+------+
-id is the primary key column for this table.
-Each row of this table contains information about the salary of an employee.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to report the <code>n<sup>th</sup></code> highest salary from the <code>Employee</code> table. If there is no <code>n<sup>th</sup></code> highest salary, the query should report <code>null</code>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Employee table:
-+----+--------+
-| id | salary |
-+----+--------+
-| 1  | 100    |
-| 2  | 200    |
-| 3  | 300    |
-+----+--------+
-n = 2
-<strong>Output:</strong> 
-+------------------------+
-| getNthHighestSalary(2) |
-+------------------------+
-| 200                    |
-+------------------------+
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Employee table:
-+----+--------+
-| id | salary |
-+----+--------+
-| 1  | 100    |
-+----+--------+
-n = 2
-<strong>Output:</strong> 
-+------------------------+
-| getNthHighestSalary(2) |
-+------------------------+
-| null                   |
-+------------------------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/nth-highest-salary/mysql_schemas.sql b/problems/nth-highest-salary/mysql_schemas.sql
deleted file mode 100644
index aca054391..000000000
--- a/problems/nth-highest-salary/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create table If Not Exists Employee (Id int, Salary int);
-Truncate table Employee;
-insert into Employee (id, salary) values ('1', '100');
-insert into Employee (id, salary) values ('2', '200');
-insert into Employee (id, salary) values ('3', '300');
diff --git a/problems/nth-highest-salary/nth_highest_salary.sql b/problems/nth-highest-salary/nth_highest_salary.sql
deleted file mode 100644
index dbea8eab4..000000000
--- a/problems/nth-highest-salary/nth_highest_salary.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
-BEGIN
-  RETURN (
-      # Write your MySQL query statement below.
-      
-  );
-END
\ No newline at end of file
diff --git a/problems/nth-magical-number/README.md b/problems/nth-magical-number/README.md
deleted file mode 100644
index 841e0934d..000000000
--- a/problems/nth-magical-number/README.md
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stone-game "Stone Game")
-　　　　　　　　　　　　　　　　
-[Next >](../profitable-schemes "Profitable Schemes")
-
-## [878. Nth Magical Number (Hard)](https://leetcode.com/problems/nth-magical-number "第 N 个神奇数字")
-
-<p>A positive integer is <em>magical</em> if it is divisible by either <code>a</code> or <code>b</code>.</p>
-
-<p>Given the three integers <code>n</code>, <code>a</code>, and <code>b</code>, return the <code>n<sup>th</sup></code> magical number. Since the answer may be very large, <strong>return it modulo </strong><code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 1, a = 2, b = 3
-<strong>Output:</strong> 2
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 4, a = 2, b = 3
-<strong>Output:</strong> 6
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> n = 5, a = 2, b = 4
-<strong>Output:</strong> 10
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> n = 3, a = 6, b = 4
-<strong>Output:</strong> 8
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-	<li><code>2 &lt;= a, b &lt;= 4 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
diff --git a/problems/nth-magical-number/nth_magical_number.go b/problems/nth-magical-number/nth_magical_number.go
deleted file mode 100644
index 49a432547..000000000
--- a/problems/nth-magical-number/nth_magical_number.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem878
diff --git a/problems/nth-magical-number/nth_magical_number_test.go b/problems/nth-magical-number/nth_magical_number_test.go
deleted file mode 100644
index 49a432547..000000000
--- a/problems/nth-magical-number/nth_magical_number_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem878
diff --git a/problems/number-complement/README.md b/problems/number-complement/README.md
deleted file mode 100644
index 63dd7a66c..000000000
--- a/problems/number-complement/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../heaters "Heaters")
-　　　　　　　　　　　　　　　　
-[Next >](../total-hamming-distance "Total Hamming Distance")
-
-## [476. Number Complement (Easy)](https://leetcode.com/problems/number-complement "数字的补数")
-
-<p>The <strong>complement</strong> of an integer is the integer you get when you flip all the <code>0</code>&#39;s to <code>1</code>&#39;s and all the <code>1</code>&#39;s to <code>0</code>&#39;s in its binary representation.</p>
-
-<ul>
-	<li>For example, The integer <code>5</code> is <code>&quot;101&quot;</code> in binary and its <strong>complement</strong> is <code>&quot;010&quot;</code> which is the integer <code>2</code>.</li>
-</ul>
-
-<p>Given an integer <code>num</code>, return <em>its complement</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 5
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 1
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num &lt; 2<sup>31</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 1009: <a href="https://leetcode.com/problems/complement-of-base-10-integer/" target="_blank">https://leetcode.com/problems/complement-of-base-10-integer/</a></p>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
diff --git a/problems/number-complement/number_complement.go b/problems/number-complement/number_complement.go
deleted file mode 100644
index 91a6616f2..000000000
--- a/problems/number-complement/number_complement.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem476
diff --git a/problems/number-complement/number_complement_test.go b/problems/number-complement/number_complement_test.go
deleted file mode 100644
index 91a6616f2..000000000
--- a/problems/number-complement/number_complement_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem476
diff --git a/problems/number-of-1-bits/README.md b/problems/number-of-1-bits/README.md
deleted file mode 100644
index 0fff41367..000000000
--- a/problems/number-of-1-bits/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-bits "Reverse Bits")
-　　　　　　　　　　　　　　　　
-[Next >](../word-frequency "Word Frequency")
-
-## [191. Number of 1 Bits (Easy)](https://leetcode.com/problems/number-of-1-bits "位1的个数")
-
-<p>Write a function that takes an unsigned integer and returns the number of &#39;1&#39; bits it has (also known as the <a href="http://en.wikipedia.org/wiki/Hamming_weight" target="_blank">Hamming weight</a>).</p>
-
-<p><strong>Note:</strong></p>
-
-<ul>
-	<li>Note that in some languages, such as Java, there is no unsigned integer type. In this case, the input will be given as a signed integer type. It should not affect your implementation, as the integer&#39;s internal binary representation is the same, whether it is signed or unsigned.</li>
-	<li>In Java, the compiler represents the signed integers using <a href="https://en.wikipedia.org/wiki/Two%27s_complement" target="_blank">2&#39;s complement notation</a>. Therefore, in <strong>Example 3</strong>, the input represents the signed integer. <code>-3</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 00000000000000000000000000001011
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The input binary string <strong>00000000000000000000000000001011</strong> has a total of three &#39;1&#39; bits.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 00000000000000000000000010000000
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The input binary string <strong>00000000000000000000000010000000</strong> has a total of one &#39;1&#39; bit.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 11111111111111111111111111111101
-<strong>Output:</strong> 31
-<strong>Explanation:</strong> The input binary string <strong>11111111111111111111111111111101</strong> has a total of thirty one &#39;1&#39; bits.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The input must be a <strong>binary string</strong> of length <code>32</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> If this function is called many times, how would you optimize it?
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Reverse Bits](../reverse-bits) (Easy)
-  1. [Power of Two](../power-of-two) (Easy)
-  1. [Counting Bits](../counting-bits) (Easy)
-  1. [Binary Watch](../binary-watch) (Easy)
-  1. [Hamming Distance](../hamming-distance) (Easy)
-  1. [Binary Number with Alternating Bits](../binary-number-with-alternating-bits) (Easy)
-  1. [Prime Number of Set Bits in Binary Representation](../prime-number-of-set-bits-in-binary-representation) (Easy)
diff --git a/problems/number-of-1-bits/number_of_1_bits.go b/problems/number-of-1-bits/number_of_1_bits.go
deleted file mode 100644
index bab7344b6..000000000
--- a/problems/number-of-1-bits/number_of_1_bits.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package problem191
-
-func hammingWeight(num uint32) int {
-	num = (num & 0x55555555) + (num>>1)&0x55555555
-	num = (num & 0x33333333) + (num>>2)&0x33333333
-	num = (num & 0x0F0F0F0F) + (num>>4)&0x0F0F0F0F
-	num = (num * 0x01010101) >> 24
-	return int(num)
-}
diff --git a/problems/number-of-1-bits/number_of_1_bits_test.go b/problems/number-of-1-bits/number_of_1_bits_test.go
deleted file mode 100644
index ead22f4c4..000000000
--- a/problems/number-of-1-bits/number_of_1_bits_test.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package problem191
-
-import "testing"
-
-type testType struct {
-	in   uint32
-	want int
-}
-
-func TestHammingWeight(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   3,
-			want: 2,
-		},
-		{
-			in:   7,
-			want: 3,
-		},
-		{
-			in:   8,
-			want: 1,
-		},
-		{
-			in:   0x5555,
-			want: 8,
-		},
-	}
-	for _, tt := range tests {
-		got := hammingWeight(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
-
-func BenchmarkHammingWeight(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		hammingWeight(0x55555555)
-	}
-}
diff --git a/problems/number-of-accounts-that-did-not-stream/README.md b/problems/number-of-accounts-that-did-not-stream/README.md
deleted file mode 100644
index d386e55a8..000000000
--- a/problems/number-of-accounts-that-did-not-stream/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-score-of-students-solving-math-expression "The Score of Students Solving Math Expression")
-　　　　　　　　　　　　　　　　
-[Next >](../brightest-position-on-street "Brightest Position on Street")
-
-## [2020. Number of Accounts That Did Not Stream (Medium)](https://leetcode.com/problems/number-of-accounts-that-did-not-stream "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/number-of-accounts-that-did-not-stream/mysql_schemas.sql b/problems/number-of-accounts-that-did-not-stream/mysql_schemas.sql
deleted file mode 100644
index 242bcbb86..000000000
--- a/problems/number-of-accounts-that-did-not-stream/mysql_schemas.sql
+++ /dev/null
@@ -1,16 +0,0 @@
-Create table If Not Exists Subscriptions (account_id int, start_date date, end_date date);
-Create table If Not Exists Streams (session_id int, account_id int, stream_date date);
-Truncate table Subscriptions;
-insert into Subscriptions (account_id, start_date, end_date) values ('9', '2020-02-18', '2021-10-30');
-insert into Subscriptions (account_id, start_date, end_date) values ('3', '2021-09-21', '2021-11-13');
-insert into Subscriptions (account_id, start_date, end_date) values ('11', '2020-02-28', '2020-08-18');
-insert into Subscriptions (account_id, start_date, end_date) values ('13', '2021-04-20', '2021-09-22');
-insert into Subscriptions (account_id, start_date, end_date) values ('4', '2020-10-26', '2021-05-08');
-insert into Subscriptions (account_id, start_date, end_date) values ('5', '2020-09-11', '2021-01-17');
-Truncate table Streams;
-insert into Streams (session_id, account_id, stream_date) values ('14', '9', '2020-05-16');
-insert into Streams (session_id, account_id, stream_date) values ('16', '3', '2021-10-27');
-insert into Streams (session_id, account_id, stream_date) values ('18', '11', '2020-04-29');
-insert into Streams (session_id, account_id, stream_date) values ('17', '13', '2021-08-08');
-insert into Streams (session_id, account_id, stream_date) values ('19', '4', '2020-12-31');
-insert into Streams (session_id, account_id, stream_date) values ('13', '5', '2021-01-05');
diff --git a/problems/number-of-atoms/README.md b/problems/number-of-atoms/README.md
deleted file mode 100644
index 0019c59b2..000000000
--- a/problems/number-of-atoms/README.md
+++ /dev/null
@@ -1,96 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-linked-list-in-parts "Split Linked List in Parts")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-window-subsequence "Minimum Window Subsequence")
-
-## [726. Number of Atoms (Hard)](https://leetcode.com/problems/number-of-atoms "原子的数量")
-
-<p>Given a string <code>formula</code> representing a chemical formula,&nbsp;return <em>the count of each atom</em>.</p>
-
-<p>The atomic element always starts with an uppercase character, then zero or more lowercase letters, representing the name.</p>
-
-<p>One or more digits representing that element&#39;s count may follow if the count is greater than <code>1</code>. If the count is <code>1</code>, no digits will follow.</p>
-
-<ul>
-	<li>For example, <code>&quot;H2O&quot;</code> and <code>&quot;H2O2&quot;</code> are possible, but <code>&quot;H1O2&quot;</code> is impossible.</li>
-</ul>
-
-<p>Two formulas are concatenated together to produce another formula.</p>
-
-<ul>
-	<li>For example, <code>&quot;H2O2He3Mg4&quot;</code> is also a formula.</li>
-</ul>
-
-<p>A formula placed in parentheses, and a count (optionally added) is also a formula.</p>
-
-<ul>
-	<li>For example, <code>&quot;(H2O2)&quot;</code> and <code>&quot;(H2O2)3&quot;</code> are formulas.</li>
-</ul>
-
-<p>Return the count of all elements as a string in the following form: the first name (in sorted order), followed by its count (if that count is more than <code>1</code>), followed by the second name (in sorted order), followed by its count (if that count is more than <code>1</code>), and so on.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> formula = &quot;H2O&quot;
-<strong>Output:</strong> &quot;H2O&quot;
-<strong>Explanation:</strong> The count of elements are {&#39;H&#39;: 2, &#39;O&#39;: 1}.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> formula = &quot;Mg(OH)2&quot;
-<strong>Output:</strong> &quot;H2MgO2&quot;
-<strong>Explanation:</strong> The count of elements are {&#39;H&#39;: 2, &#39;Mg&#39;: 1, &#39;O&#39;: 2}.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> formula = &quot;K4(ON(SO3)2)2&quot;
-<strong>Output:</strong> &quot;K4N2O14S4&quot;
-<strong>Explanation:</strong> The count of elements are {&#39;K&#39;: 4, &#39;N&#39;: 2, &#39;O&#39;: 14, &#39;S&#39;: 4}.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> formula = &quot;Be32&quot;
-<strong>Output:</strong> &quot;Be32&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= formula.length&nbsp;&lt;= 1000</code></li>
-	<li><code>formula</code> consists of English letters, digits, <code>&#39;(&#39;</code>, and <code>&#39;)&#39;</code>.</li>
-	<li><code>formula</code> is always valid.</li>
-	<li>All the values in the output will fit in a 32-bit integer.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Decode String](../decode-string) (Medium)
-  1. [Encode String with Shortest Length](../encode-string-with-shortest-length) (Hard)
-  1. [Parse Lisp Expression](../parse-lisp-expression) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-To parse formula[i:], when we see a `'('`, we will parse recursively whatever is inside the brackets (up to the correct closing ending bracket) and add it to our count, multiplying by the following multiplicity if there is one.
-
-Otherwise, we should see an uppercase character: we will parse the rest of the letters to get the name, and add that (plus the multiplicity if there is one.)
-</details>
diff --git a/problems/number-of-atoms/number_of_atoms.go b/problems/number-of-atoms/number_of_atoms.go
deleted file mode 100644
index 941046264..000000000
--- a/problems/number-of-atoms/number_of_atoms.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem726
diff --git a/problems/number-of-atoms/number_of_atoms_test.go b/problems/number-of-atoms/number_of_atoms_test.go
deleted file mode 100644
index 941046264..000000000
--- a/problems/number-of-atoms/number_of_atoms_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem726
diff --git a/problems/number-of-boomerangs/README.md b/problems/number-of-boomerangs/README.md
deleted file mode 100644
index 236720226..000000000
--- a/problems/number-of-boomerangs/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../arithmetic-slices-ii-subsequence "Arithmetic Slices II - Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../find-all-numbers-disappeared-in-an-array "Find All Numbers Disappeared in an Array")
-
-## [447. Number of Boomerangs (Medium)](https://leetcode.com/problems/number-of-boomerangs "回旋镖的数量")
-
-<p>You are given <code>n</code> <code>points</code> in the plane that are all <strong>distinct</strong>, where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>. A <strong>boomerang</strong> is a tuple of points <code>(i, j, k)</code> such that the distance between <code>i</code> and <code>j</code> equals the distance between <code>i</code> and <code>k</code> <strong>(the order of the tuple matters)</strong>.</p>
-
-<p>Return <em>the number of boomerangs</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[0,0],[1,0],[2,0]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The two boomerangs are [[1,0],[0,0],[2,0]] and [[1,0],[2,0],[0,0]].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[1,1],[2,2],[3,3]]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[1,1]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == points.length</code></li>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>-10<sup>4</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li>All the points are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Line Reflection](../line-reflection) (Medium)
diff --git a/problems/number-of-boomerangs/number_of_boomerangs.go b/problems/number-of-boomerangs/number_of_boomerangs.go
deleted file mode 100644
index 7c071e644..000000000
--- a/problems/number-of-boomerangs/number_of_boomerangs.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem447
diff --git a/problems/number-of-boomerangs/number_of_boomerangs_test.go b/problems/number-of-boomerangs/number_of_boomerangs_test.go
deleted file mode 100644
index 7c071e644..000000000
--- a/problems/number-of-boomerangs/number_of_boomerangs_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem447
diff --git a/problems/number-of-burgers-with-no-waste-of-ingredients/README.md b/problems/number-of-burgers-with-no-waste-of-ingredients/README.md
deleted file mode 100644
index 2d56fac68..000000000
--- a/problems/number-of-burgers-with-no-waste-of-ingredients/README.md
+++ /dev/null
@@ -1,98 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-winner-on-a-tic-tac-toe-game "Find Winner on a Tic Tac Toe Game")
-　　　　　　　　　　　　　　　　
-[Next >](../count-square-submatrices-with-all-ones "Count Square Submatrices with All Ones")
-
-## [1276. Number of Burgers with No Waste of Ingredients (Medium)](https://leetcode.com/problems/number-of-burgers-with-no-waste-of-ingredients "不浪费原料的汉堡制作方案")
-
-<p>Given two integers <code>tomatoSlices</code>&nbsp;and <code>cheeseSlices</code>. The ingredients of different burgers are as follows:</p>
-
-<ul>
-	<li><strong>Jumbo Burger:</strong> 4 tomato slices&nbsp;and 1 cheese slice.</li>
-	<li><strong>Small Burger:</strong> 2 Tomato slices&nbsp;and 1 cheese slice.</li>
-</ul>
-
-<p>Return <code>[total_jumbo, total_small]</code> so that the number of remaining <code>tomatoSlices</code>&nbsp;equal to 0 and the number of remaining <code>cheeseSlices</code> equal to 0. If it is not possible to make the remaining <code>tomatoSlices</code>&nbsp;and <code>cheeseSlices</code> equal to 0 return <code>[]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tomatoSlices = 16, cheeseSlices = 7
-<strong>Output:</strong> [1,6]
-<strong>Explantion:</strong> To make one jumbo burger and 6 small burgers we need 4*1 + 2*6 = 16 tomato and 1 + 6 = 7 cheese. There will be no remaining ingredients.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tomatoSlices = 17, cheeseSlices = 4
-<strong>Output:</strong> []
-<strong>Explantion:</strong> There will be no way to use all ingredients to make small and jumbo burgers.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> tomatoSlices = 4, cheeseSlices = 17
-<strong>Output:</strong> []
-<strong>Explantion:</strong> Making 1 jumbo burger there will be 16 cheese remaining and making 2 small burgers there will be 15 cheese remaining.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> tomatoSlices = 0, cheeseSlices = 0
-<strong>Output:</strong> [0,0]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> tomatoSlices = 2, cheeseSlices = 1
-<strong>Output:</strong> [0,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= tomatoSlices &lt;= 10^7</code></li>
-	<li><code>0 &lt;= cheeseSlices &lt;= 10^7</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we have an answer if the number of tomatoes is odd ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If we have answer will be there multiple answers or just one answer ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Let us define number of jumbo burgers as X and number of small burgers as Y
-We have to find an x and y in this equation
-</details>
-
-<details>
-<summary>Hint 4</summary>
-1. 4X + 2Y = tomato
-</details>
-
-<details>
-<summary>Hint 5</summary>
-2. X + Y = cheese
-</details>
diff --git a/problems/number-of-calls-between-two-persons/README.md b/problems/number-of-calls-between-two-persons/README.md
deleted file mode 100644
index 341c37f73..000000000
--- a/problems/number-of-calls-between-two-persons/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-distinct-substrings-in-a-string "Number of Distinct Substrings in a String")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-students-unable-to-eat-lunch "Number of Students Unable to Eat Lunch")
-
-## [1699. Number of Calls Between Two Persons (Medium)](https://leetcode.com/problems/number-of-calls-between-two-persons "两人之间的通话次数")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/number-of-calls-between-two-persons/mysql_schemas.sql b/problems/number-of-calls-between-two-persons/mysql_schemas.sql
deleted file mode 100644
index d2578c68b..000000000
--- a/problems/number-of-calls-between-two-persons/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Calls (from_id int, to_id int, duration int);
-Truncate table Calls;
-insert into Calls (from_id, to_id, duration) values ('1', '2', '59');
-insert into Calls (from_id, to_id, duration) values ('2', '1', '11');
-insert into Calls (from_id, to_id, duration) values ('1', '3', '20');
-insert into Calls (from_id, to_id, duration) values ('3', '4', '100');
-insert into Calls (from_id, to_id, duration) values ('3', '4', '200');
-insert into Calls (from_id, to_id, duration) values ('3', '4', '200');
-insert into Calls (from_id, to_id, duration) values ('4', '3', '499');
diff --git a/problems/number-of-closed-islands/README.md b/problems/number-of-closed-islands/README.md
deleted file mode 100644
index 1c2c4e1ee..000000000
--- a/problems/number-of-closed-islands/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reconstruct-a-2-row-binary-matrix "Reconstruct a 2-Row Binary Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-score-words-formed-by-letters "Maximum Score Words Formed by Letters")
-
-## [1254. Number of Closed Islands (Medium)](https://leetcode.com/problems/number-of-closed-islands "统计封闭岛屿的数目")
-
-<p>Given a 2D&nbsp;<code>grid</code> consists of <code>0s</code> (land)&nbsp;and <code>1s</code> (water).&nbsp; An <em>island</em> is a maximal 4-directionally connected group of <code><font face="monospace">0</font>s</code> and a <em>closed island</em>&nbsp;is an island <strong>totally</strong>&nbsp;(all left, top, right, bottom) surrounded by <code>1s.</code></p>
-
-<p>Return the number of <em>closed islands</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_3_1610.png" style="width: 240px; height: 120px;" /></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,1,1,1,1,1,0],[1,0,0,0,0,1,1,0],[1,0,1,0,1,1,1,0],[1,0,0,0,0,1,0,1],[1,1,1,1,1,1,1,0]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-Islands in gray are closed because they are completely surrounded by water (group of 1s).</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_4_1610.png" style="width: 160px; height: 80px;" /></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0,0,1,0,0],[0,1,0,1,0],[0,1,1,1,0]]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,1,1,1,1,1],
-&nbsp;              [1,0,0,0,0,0,1],
-&nbsp;              [1,0,1,1,1,0,1],
-&nbsp;              [1,0,1,0,1,0,1],
-&nbsp;              [1,0,1,1,1,0,1],
-&nbsp;              [1,0,0,0,0,0,1],
-               [1,1,1,1,1,1,1]]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= grid.length, grid[0].length &lt;= 100</code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;=1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Exclude connected group of 0s on the corners because they are not closed island.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Return number of connected component of 0s on the grid.
-</details>
diff --git a/problems/number-of-comments-per-post/README.md b/problems/number-of-comments-per-post/README.md
deleted file mode 100644
index b190512bd..000000000
--- a/problems/number-of-comments-per-post/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tiling-a-rectangle-with-the-fewest-squares "Tiling a Rectangle with the Fewest Squares")
-　　　　　　　　　　　　　　　　
-[Next >](../web-crawler-multithreaded "Web Crawler Multithreaded")
-
-## [1241. Number of Comments per Post (Easy)](https://leetcode.com/problems/number-of-comments-per-post "每个帖子的评论数")
-
-<p>Table: <code>Submissions</code></p>
-
-<pre>+---------------+----------+
-| Column Name   | Type     |
-+---------------+----------+
-| sub_id        | int      |
-| parent_id     | int      |
-+---------------+----------+
-There is no primary key for this table, it may have duplicate rows.
-Each row can be a post or comment on the post.
-parent_id is null for posts.
-parent_id for comments is <code>sub_id</code> for another post in the table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find number of comments per each post.</p>
-
-<p>Result table should contain <code>post_id</code> and its corresponding&nbsp;<code>number_of_comments</code>, and&nbsp;must be sorted by <code>post_id&nbsp;</code>in ascending order.</p>
-
-<p><code>Submissions</code> may contain duplicate comments. You should count the number of <strong>unique comments</strong> per post.</p>
-
-<p><code>Submissions</code> may contain duplicate posts. You should treat them as one post.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>Submissions table:
-+---------+------------+
-| sub_id  | parent_id  |
-+---------+------------+
-| 1       | Null       |
-| 2       | Null       |
-| 1       | Null       |
-| 12      | Null       |
-| 3       | 1          |
-| 5       | 2          |
-| 3       | 1          |
-| 4       | 1          |
-| 9       | 1          |
-| 10      | 2          |
-| 6       | 7          |
-+---------+------------+
-
-Result table:
-+---------+--------------------+
-| post_id | number_of_comments |
-+---------+--------------------+
-| 1       | 3                  |
-| 2       | 2                  |
-| 12      | 0                  |
-+---------+--------------------+
-
-The post with id 1 has three comments in the table with id 3, 4 and 9. The comment with id 3 is repeated in the table, we counted it <strong>only once</strong>.
-The post with id 2 has two comments in the table with id 5 and 10.
-The post with id 12 has no comments in the table.
-The comment with id 6 is a comment on a deleted post with id 7 so we ignored it.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/number-of-comments-per-post/mysql_schemas.sql b/problems/number-of-comments-per-post/mysql_schemas.sql
deleted file mode 100644
index cf53a553f..000000000
--- a/problems/number-of-comments-per-post/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Submissions (sub_id int, parent_id int);
-Truncate table Submissions;
-insert into Submissions (sub_id, parent_id) values ('1', 'None');
-insert into Submissions (sub_id, parent_id) values ('2', 'None');
-insert into Submissions (sub_id, parent_id) values ('1', 'None');
-insert into Submissions (sub_id, parent_id) values ('12', 'None');
-insert into Submissions (sub_id, parent_id) values ('3', '1');
-insert into Submissions (sub_id, parent_id) values ('5', '2');
-insert into Submissions (sub_id, parent_id) values ('3', '1');
-insert into Submissions (sub_id, parent_id) values ('4', '1');
-insert into Submissions (sub_id, parent_id) values ('9', '1');
-insert into Submissions (sub_id, parent_id) values ('10', '2');
-insert into Submissions (sub_id, parent_id) values ('6', '7');
diff --git a/problems/number-of-connected-components-in-an-undirected-graph/README.md b/problems/number-of-connected-components-in-an-undirected-graph/README.md
deleted file mode 100644
index c7a635238..000000000
--- a/problems/number-of-connected-components-in-an-undirected-graph/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../coin-change "Coin Change")
-　　　　　　　　　　　　　　　　
-[Next >](../wiggle-sort-ii "Wiggle Sort II")
-
-## [323. Number of Connected Components in an Undirected Graph (Medium)](https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph "无向图中连通分量的数目")
-
-<p>Given <code>n</code> nodes labeled from <code>0</code> to <code>n - 1</code> and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected components in an undirected graph.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<strong>Input: </strong><code>n = 5</code> and <code>edges = [[0, 1], [1, 2], [3, 4]]</code>
-
-     0          3
-     |          |
-     1 --- 2    4 
-
-<strong>Output: </strong>2
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<strong>Input: </strong><code>n = 5</code> and <code>edges = [[0, 1], [1, 2], [2, 3], [3, 4]]</code>
-
-     0           4
-     |           |
-     1 --- 2 --- 3
-
-<strong>Output:&nbsp;&nbsp;</strong>1
-</pre>
-
-<p><b>Note:</b><br />
-You can assume that no duplicate edges will appear in <code>edges</code>. Since all edges are undirected, <code>[0, 1]</code> is the same as <code>[1, 0]</code> and thus will not appear together in <code>edges</code>.</p>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [Number of Islands](../number-of-islands) (Medium)
-  1. [Graph Valid Tree](../graph-valid-tree) (Medium)
-  1. [Number of Provinces](../number-of-provinces) (Medium)
diff --git a/problems/number-of-connected-components-in-an-undirected-graph/number_of_connected_components_in_an_undirected_graph.go b/problems/number-of-connected-components-in-an-undirected-graph/number_of_connected_components_in_an_undirected_graph.go
deleted file mode 100644
index 0ff0babab..000000000
--- a/problems/number-of-connected-components-in-an-undirected-graph/number_of_connected_components_in_an_undirected_graph.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem323
diff --git a/problems/number-of-connected-components-in-an-undirected-graph/number_of_connected_components_in_an_undirected_graph_test.go b/problems/number-of-connected-components-in-an-undirected-graph/number_of_connected_components_in_an_undirected_graph_test.go
deleted file mode 100644
index 0ff0babab..000000000
--- a/problems/number-of-connected-components-in-an-undirected-graph/number_of_connected_components_in_an_undirected_graph_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem323
diff --git a/problems/number-of-corner-rectangles/README.md b/problems/number-of-corner-rectangles/README.md
deleted file mode 100644
index d504a9398..000000000
--- a/problems/number-of-corner-rectangles/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../contain-virus "Contain Virus")
-　　　　　　　　　　　　　　　　
-[Next >](../ip-to-cidr "IP to CIDR")
-
-## [750. Number Of Corner Rectangles (Medium)](https://leetcode.com/problems/number-of-corner-rectangles "角矩形的数量")
-
-<p>Given a grid where each entry is only 0 or 1, find the number of corner rectangles.</p>
-
-<p>A <em>corner rectangle</em> is 4 distinct 1s on the grid that form an axis-aligned rectangle. Note that only the corners need to have the value 1. Also, all four 1s used must be distinct.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = 
-[[1, 0, 0, 1, 0],
- [0, 0, 1, 0, 1],
- [0, 0, 0, 1, 0],
- [1, 0, 1, 0, 1]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There is only one corner rectangle, with corners grid[1][2], grid[1][4], grid[3][2], grid[3][4].
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = 
-[[1, 1, 1],
- [1, 1, 1],
- [1, 1, 1]]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> There are four 2x2 rectangles, four 2x3 and 3x2 rectangles, and one 3x3 rectangle.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = 
-[[1, 1, 1, 1]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Rectangles must have four distinct corners.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>The number of rows and columns of <code>grid</code> will each be in the range <code>[1, 200]</code>.</li>
-	<li>Each <code>grid[i][j]</code> will be either <code>0</code> or <code>1</code>.</li>
-	<li>The number of <code>1</code>s in the grid will be at most <code>6000</code>.</li>
-</ol>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each pair of 1s in the new row (say at `new_row[i]` and `new_row[j]`), we could create more rectangles where that pair forms the base.  The number of new rectangles is the number of times some previous row had `row[i] = row[j] = 1`.
-</details>
diff --git a/problems/number-of-corner-rectangles/number_of_corner_rectangles.go b/problems/number-of-corner-rectangles/number_of_corner_rectangles.go
deleted file mode 100644
index c6028923f..000000000
--- a/problems/number-of-corner-rectangles/number_of_corner_rectangles.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem750
diff --git a/problems/number-of-corner-rectangles/number_of_corner_rectangles_test.go b/problems/number-of-corner-rectangles/number_of_corner_rectangles_test.go
deleted file mode 100644
index c6028923f..000000000
--- a/problems/number-of-corner-rectangles/number_of_corner_rectangles_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem750
diff --git a/problems/number-of-days-between-two-dates/README.md b/problems/number-of-days-between-two-dates/README.md
deleted file mode 100644
index 6f1fd8d63..000000000
--- a/problems/number-of-days-between-two-dates/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-all-valid-pickup-and-delivery-options "Count All Valid Pickup and Delivery Options")
-　　　　　　　　　　　　　　　　
-[Next >](../validate-binary-tree-nodes "Validate Binary Tree Nodes")
-
-## [1360. Number of Days Between Two Dates (Easy)](https://leetcode.com/problems/number-of-days-between-two-dates "日期之间隔几天")
-
-<p>Write a program to count the number of days between two dates.</p>
-
-<p>The two dates are given as strings, their format is <code>YYYY-MM-DD</code>&nbsp;as shown in the examples.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> date1 = "2019-06-29", date2 = "2019-06-30"
-<strong>Output:</strong> 1
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> date1 = "2020-01-15", date2 = "2019-12-31"
-<strong>Output:</strong> 15
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The given dates are valid&nbsp;dates between the years <code>1971</code> and <code>2100</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create a function f(date) that counts the number of days from 1900-01-01 to date. How can we calculate the answer ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The answer is just |f(date1) - f(date2)|.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How to construct f(date) ?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For each year from 1900 to year - 1 sum up 365 or 366 in case of leap years. Then sum up for each month the number of days, consider the case when the current year is leap, finally sum up the days.
-</details>
diff --git a/problems/number-of-days-in-a-month/README.md b/problems/number-of-days-in-a-month/README.md
deleted file mode 100644
index 217dbebec..000000000
--- a/problems/number-of-days-in-a-month/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../building-h2o "Building H2O")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-vowels-from-a-string "Remove Vowels from a String")
-
-## [1118. Number of Days in a Month (Easy)](https://leetcode.com/problems/number-of-days-in-a-month "一月有多少天")
-
-<p>Given a year <code>Y</code> and a month <code>M</code>, return how many days there are in that month.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>Y = <span id="example-input-1-1">1992</span>, M = <span id="example-input-1-2">7</span>
-<strong>Output: </strong><span id="example-output-1">31</span>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>Y = <span id="example-input-2-1">2000</span>, M = <span id="example-input-2-2">2</span>
-<strong>Output: </strong><span id="example-output-2">29</span>
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong>Y = <span id="example-input-3-1">1900</span>, M = <span id="example-input-3-2">2</span>
-<strong>Output: </strong><span id="example-output-3">28</span>
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1583 &lt;= Y &lt;= 2100</code></li>
-	<li><code>1 &lt;= M &lt;= 12</code></li>
-</ol>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Does February have 28 days or 29 days?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think of Leap years.
-</details>
diff --git a/problems/number-of-dice-rolls-with-target-sum/README.md b/problems/number-of-dice-rolls-with-target-sum/README.md
deleted file mode 100644
index 2a075c709..000000000
--- a/problems/number-of-dice-rolls-with-target-sum/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../day-of-the-year "Day of the Year")
-　　　　　　　　　　　　　　　　
-[Next >](../swap-for-longest-repeated-character-substring "Swap For Longest Repeated Character Substring")
-
-## [1155. Number of Dice Rolls With Target Sum (Medium)](https://leetcode.com/problems/number-of-dice-rolls-with-target-sum "掷骰子的N种方法")
-
-<p>You have <code>n</code> dice and each die has <code>k</code> faces numbered from <code>1</code> to <code>k</code>.</p>
-
-<p>Given three integers <code>n</code>, <code>k</code>, and <code>target</code>, return <em>the number of possible ways (out of the </em><code>k<sup>n</sup></code><em> total ways) </em><em>to roll the dice so the sum of the face-up numbers equals </em><code>target</code>. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, k = 6, target = 3
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You throw one die with 6 faces.
-There is only one way to get a sum of 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, k = 6, target = 7
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> You throw two dice, each with 6 faces.
-There are 6 ways to get a sum of 7: 1+6, 2+5, 3+4, 4+3, 5+2, 6+1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 30, k = 30, target = 500
-<strong>Output:</strong> 222616187
-<strong>Explanation:</strong> The answer must be returned modulo 10<sup>9</sup> + 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n, k &lt;= 30</code></li>
-	<li><code>1 &lt;= target &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Equal Sum Arrays With Minimum Number of Operations](../equal-sum-arrays-with-minimum-number-of-operations) (Medium)
-  1. [Find Missing Observations](../find-missing-observations) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.  The states are how many dice are remaining, and what sum total you have rolled so far.
-</details>
diff --git a/problems/number-of-different-integers-in-a-string/README.md b/problems/number-of-different-integers-in-a-string/README.md
deleted file mode 100644
index 0da225fa1..000000000
--- a/problems/number-of-different-integers-in-a-string/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../implement-trie-ii-prefix-tree "Implement Trie II (Prefix Tree)")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-operations-to-reinitialize-a-permutation "Minimum Number of Operations to Reinitialize a Permutation")
-
-## [1805. Number of Different Integers in a String (Easy)](https://leetcode.com/problems/number-of-different-integers-in-a-string "字符串中不同整数的数目")
-
-<p>You are given a string <code>word</code> that consists of digits and lowercase English letters.</p>
-
-<p>You will replace every non-digit character with a space. For example, <code>&quot;a123bc34d8ef34&quot;</code> will become <code>&quot; 123&nbsp; 34 8&nbsp; 34&quot;</code>. Notice that you are left with some integers that are separated by at least one space: <code>&quot;123&quot;</code>, <code>&quot;34&quot;</code>, <code>&quot;8&quot;</code>, and <code>&quot;34&quot;</code>.</p>
-
-<p>Return <em>the number of <strong>different</strong> integers after performing the replacement operations on </em><code>word</code>.</p>
-
-<p>Two integers are considered different if their decimal representations <strong>without any leading zeros</strong> are different.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;a<u>123</u>bc<u>34</u>d<u>8</u>ef<u>34</u>&quot;
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>The three different integers are &quot;123&quot;, &quot;34&quot;, and &quot;8&quot;. Notice that &quot;34&quot; is only counted once.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;leet<u>1234</u>code<u>234</u>&quot;
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;a<u>1</u>b<u>01</u>c<u>001</u>&quot;
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>The three integers &quot;1&quot;, &quot;01&quot;, and &quot;001&quot; all represent the same integer because
-the leading zeros are ignored when comparing their decimal values.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length &lt;= 1000</code></li>
-	<li><code>word</code> consists of digits and lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to split the string so that each integer is in a different string.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to remove each integer's leading zeroes and compare the strings to find how many of them are unique.
-</details>
diff --git a/problems/number-of-different-subsequences-gcds/README.md b/problems/number-of-different-subsequences-gcds/README.md
deleted file mode 100644
index 3665c4ac0..000000000
--- a/problems/number-of-different-subsequences-gcds/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-absolute-sum-difference "Minimum Absolute Sum Difference")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-accepted-invitations "Maximum Number of Accepted Invitations")
-
-## [1819. Number of Different Subsequences GCDs (Hard)](https://leetcode.com/problems/number-of-different-subsequences-gcds "序列中不同最大公约数的数目")
-
-<p>You are given an array <code>nums</code> that consists of positive integers.</p>
-
-<p>The <strong>GCD</strong> of a sequence of numbers is defined as the greatest integer that divides <strong>all</strong> the numbers in the sequence evenly.</p>
-
-<ul>
-	<li>For example, the GCD of the sequence <code>[4,6,16]</code> is <code>2</code>.</li>
-</ul>
-
-<p>A <strong>subsequence</strong> of an array is a sequence that can be formed by removing some elements (possibly none) of the array.</p>
-
-<ul>
-	<li>For example, <code>[2,5,10]</code> is a subsequence of <code>[1,2,1,<strong><u>2</u></strong>,4,1,<u><strong>5</strong></u>,<u><strong>10</strong></u>]</code>.</li>
-</ul>
-
-<p>Return <em>the <strong>number</strong> of <strong>different</strong> GCDs among all <strong>non-empty</strong> subsequences of</em> <code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/17/image-1.png" style="width: 149px; height: 309px;" />
-<pre>
-<strong>Input:</strong> nums = [6,10,3]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The figure shows all the non-empty subsequences and their GCDs.
-The different GCDs are 6, 10, 3, 2, and 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,15,40,5,6]
-<strong>Output:</strong> 7
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 2 * 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Number Theory](../../tag/number-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think of how to check if a number x is a gcd of a subsequence.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If there is such subsequence, then all of it will be divisible by x. Moreover, if you divide each number in the subsequence by x , then the gcd of the resulting numbers will be 1.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Adding a number to a subsequence cannot increase its gcd. So, if there is a valid subsequence for x , then the subsequence that contains all multiples of x is a valid one too.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Iterate on all possiblex from 1 to 10^5, and check if there is a valid subsequence for x.
-</details>
diff --git a/problems/number-of-digit-one/README.md b/problems/number-of-digit-one/README.md
deleted file mode 100644
index efc194352..000000000
--- a/problems/number-of-digit-one/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../implement-queue-using-stacks "Implement Queue using Stacks")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-linked-list "Palindrome Linked List")
-
-## [233. Number of Digit One (Hard)](https://leetcode.com/problems/number-of-digit-one "数字 1 的个数")
-
-<p>Given an integer <code>n</code>, count <em>the total number of digit </em><code>1</code><em> appearing in all non-negative integers less than or equal to</em> <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 13
-<strong>Output:</strong> 6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-
-### Similar Questions
-  1. [Factorial Trailing Zeroes](../factorial-trailing-zeroes) (Medium)
-  1. [Digit Count in Range](../digit-count-in-range) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Beware of overflow.
-</details>
diff --git a/problems/number-of-digit-one/number_of_digit_one.go b/problems/number-of-digit-one/number_of_digit_one.go
deleted file mode 100644
index f23d90680..000000000
--- a/problems/number-of-digit-one/number_of_digit_one.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem233
-
-func countDigitOne(n int) int {
-	ans, b, x := 0, 1, 0
-	for b <= n {
-		x = n / b
-		ans += (x + 8) / 10 * b
-		if x%10 == 1 {
-			ans += n%b + 1
-		}
-		b *= 10
-	}
-	return ans
-}
diff --git a/problems/number-of-digit-one/number_of_digit_one_test.go b/problems/number-of-digit-one/number_of_digit_one_test.go
deleted file mode 100644
index 7ee2365cb..000000000
--- a/problems/number-of-digit-one/number_of_digit_one_test.go
+++ /dev/null
@@ -1,67 +0,0 @@
-package problem233
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestCountDigitOne(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   0,
-			want: 0,
-		},
-		{
-			in:   1,
-			want: 1,
-		},
-		{
-			in:   12,
-			want: 5,
-		},
-		{
-			in:   99,
-			want: 20,
-		},
-		{
-			in:   100,
-			want: 21,
-		},
-		{
-			in:   123,
-			want: 57,
-		},
-		{
-			in:   1234,
-			want: 689,
-		},
-		{
-			in:   12345,
-			want: 8121,
-		},
-		{
-			in:   123456,
-			want: 93553,
-		},
-		{
-			in:   1234567,
-			want: 1058985,
-		},
-		{
-			in:   12345678,
-			want: 11824417,
-		},
-		{
-			in:   123456789,
-			want: 130589849,
-		},
-	}
-	for _, tt := range tests {
-		got := countDigitOne(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/number-of-distinct-islands-ii/README.md b/problems/number-of-distinct-islands-ii/README.md
deleted file mode 100644
index fd7dc2e14..000000000
--- a/problems/number-of-distinct-islands-ii/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../random-pick-with-blacklist "Random Pick with Blacklist")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-ascii-delete-sum-for-two-strings "Minimum ASCII Delete Sum for Two Strings")
-
-## [711. Number of Distinct Islands II (Hard)](https://leetcode.com/problems/number-of-distinct-islands-ii "不同岛屿的数量 II")
-
-<p>Given a non-empty 2D array <code>grid</code> of 0's and 1's, an <b>island</b> is a group of <code>1</code>'s (representing land) connected 4-directionally (horizontal or vertical.)  You may assume all four edges of the grid are surrounded by water.</p>
-
-<p>Count the number of <b>distinct</b> islands.  An island is considered to be the same as another if they have the same shape, or have the same shape after <b>rotation</b> (90, 180, or 270 degrees only) or <b>reflection</b> (left/right direction or up/down direction).</p>
-
-<p><b>Example 1:</b><br />
-<pre>
-11000
-10000
-00001
-00011
-</pre>
-Given the above grid map, return <code>1</code>.
-<br><br>
-Notice that:
-<pre>
-11
-1
-</pre>
-and
-<pre>
- 1
-11
-</pre>
-are considered <b>same</b> island shapes. Because if we make a 180 degrees clockwise rotation on the first island, then two islands will have the same shapes.
-</p>
-
-<p><b>Example 2:</b><br />
-<pre>
-11100
-10001
-01001
-01110</pre>
-Given the above grid map, return <code>2</code>.<br />
-<br>
-Here are the two distinct islands:
-<pre>
-111
-1
-</pre>
-and
-<pre>
-1
-1
-</pre>
-<br />
-Notice that:
-<pre>
-111
-1
-</pre>
-and
-<pre>
-1
-111
-</pre>
-are considered <b>same</b> island shapes. Because if we flip the first array in the up/down direction, then they have the same shapes.
-</p>
-
-<p><b>Note:</b>
-The length of each dimension in the given <code>grid</code> does not exceed 50.
-</p>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Similar Questions
-  1. [Number of Distinct Islands](../number-of-distinct-islands) (Medium)
diff --git a/problems/number-of-distinct-islands-ii/number_of_distinct_islands_ii.go b/problems/number-of-distinct-islands-ii/number_of_distinct_islands_ii.go
deleted file mode 100644
index 3aae5265d..000000000
--- a/problems/number-of-distinct-islands-ii/number_of_distinct_islands_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem711
diff --git a/problems/number-of-distinct-islands-ii/number_of_distinct_islands_ii_test.go b/problems/number-of-distinct-islands-ii/number_of_distinct_islands_ii_test.go
deleted file mode 100644
index 3aae5265d..000000000
--- a/problems/number-of-distinct-islands-ii/number_of_distinct_islands_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem711
diff --git a/problems/number-of-distinct-islands/README.md b/problems/number-of-distinct-islands/README.md
deleted file mode 100644
index 67b054bcc..000000000
--- a/problems/number-of-distinct-islands/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-number-with-alternating-bits "Binary Number with Alternating Bits")
-　　　　　　　　　　　　　　　　
-[Next >](../max-area-of-island "Max Area of Island")
-
-## [694. Number of Distinct Islands (Medium)](https://leetcode.com/problems/number-of-distinct-islands "不同岛屿的数量")
-
-<p>Given a non-empty 2D array <code>grid</code> of 0's and 1's, an <b>island</b> is a group of <code>1</code>'s (representing land) connected 4-directionally (horizontal or vertical.)  You may assume all four edges of the grid are surrounded by water.</p>
-
-<p>Count the number of <b>distinct</b> islands.  An island is considered to be the same as another if and only if one island can be translated (and not rotated or reflected) to equal the other.</p>
-
-<p><b>Example 1:</b><br />
-<pre>
-11000
-11000
-00011
-00011
-</pre>
-Given the above grid map, return <code>1</code>.
-</p>
-
-<p><b>Example 2:</b><br />
-<pre>11011
-10000
-00001
-11011</pre>
-Given the above grid map, return <code>3</code>.<br /><br />
-Notice that:
-<pre>
-11
-1
-</pre>
-and
-<pre>
- 1
-11
-</pre>
-are considered different island shapes, because we do not consider reflection / rotation.
-</p>
-
-<p><b>Note:</b>
-The length of each dimension in the given <code>grid</code> does not exceed 50.
-</p>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Similar Questions
-  1. [Number of Islands](../number-of-islands) (Medium)
-  1. [Number of Distinct Islands II](../number-of-distinct-islands-ii) (Hard)
diff --git a/problems/number-of-distinct-islands/number_of_distinct_islands.go b/problems/number-of-distinct-islands/number_of_distinct_islands.go
deleted file mode 100644
index cf18ea1fe..000000000
--- a/problems/number-of-distinct-islands/number_of_distinct_islands.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem694
diff --git a/problems/number-of-distinct-islands/number_of_distinct_islands_test.go b/problems/number-of-distinct-islands/number_of_distinct_islands_test.go
deleted file mode 100644
index cf18ea1fe..000000000
--- a/problems/number-of-distinct-islands/number_of_distinct_islands_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem694
diff --git a/problems/number-of-distinct-substrings-in-a-string/README.md b/problems/number-of-distinct-substrings-in-a-string/README.md
deleted file mode 100644
index 97806c83a..000000000
--- a/problems/number-of-distinct-substrings-in-a-string/README.md
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../checking-existence-of-edge-length-limited-paths "Checking Existence of Edge Length Limited Paths")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-calls-between-two-persons "Number of Calls Between Two Persons")
-
-## [1698. Number of Distinct Substrings in a String (Medium)](https://leetcode.com/problems/number-of-distinct-substrings-in-a-string "字符串的不同子字符串个数")
-
-
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-  [[Suffix Array](../../tag/suffix-array/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Calculate the prefix hashing array for s.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the prefix hashing array to calculate the hashing value of each substring.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Compare the hashing values to determine the unique substrings.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-There could be collisions if you use hashing, what about double hashing.
-</details>
diff --git a/problems/number-of-enclaves/README.md b/problems/number-of-enclaves/README.md
deleted file mode 100644
index 7a7d21404..000000000
--- a/problems/number-of-enclaves/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../next-greater-node-in-linked-list "Next Greater Node In Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-outermost-parentheses "Remove Outermost Parentheses")
-
-## [1020. Number of Enclaves (Medium)](https://leetcode.com/problems/number-of-enclaves "飞地的数量")
-
-<p>You are given an <code>m x n</code> binary matrix <code>grid</code>, where <code>0</code> represents a sea cell and <code>1</code> represents a land cell.</p>
-
-<p>A <strong>move</strong> consists of walking from one land cell to another adjacent (<strong>4-directionally</strong>) land cell or walking off the boundary of the <code>grid</code>.</p>
-
-<p>Return <em>the number of land cells in</em> <code>grid</code> <em>for which we cannot walk off the boundary of the grid in any number of <strong>moves</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/enclaves1.jpg" style="width: 333px; height: 333px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,0,0,0],[1,0,1,0],[0,1,1,0],[0,0,0,0]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> There are three 1s that are enclosed by 0s, and one 1 that is not enclosed because its on the boundary.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/enclaves2.jpg" style="width: 333px; height: 333px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1,1,0],[0,0,1,0],[0,0,1,0],[0,0,0,0]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> All 1s are either on the boundary or can reach the boundary.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 500</code></li>
-	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you model this problem as a graph problem?  Create n * m + 1 nodes where n * m nodes represents each cell of the map and one extra node to represent the exterior of the map.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In the map add edges between neighbors on land cells. And add edges between the exterior and land nodes which are in the boundary.
-Return as answer the number of nodes that are not reachable from the exterior node.
-</details>
diff --git a/problems/number-of-enclaves/number_of_enclaves.go b/problems/number-of-enclaves/number_of_enclaves.go
deleted file mode 100644
index 360588a7c..000000000
--- a/problems/number-of-enclaves/number_of_enclaves.go
+++ /dev/null
@@ -1,44 +0,0 @@
-package problem1020
-
-var dx = [4]int{-1, 1, 0, 0}
-var dy = [4]int{0, 0, -1, 1}
-
-func numEnclaves(A [][]int) int {
-	m, n := len(A), len(A[0])
-
-	var dfs func(int, int)
-	dfs = func(x, y int) {
-		if x < 0 || m <= x ||
-			y < 0 || n <= y ||
-			A[x][y] == 0 {
-			return
-		}
-		A[x][y] = 0
-		for i := 0; i < 4; i++ {
-			dfs(x+dx[i], y+dy[i])
-		}
-	}
-
-	line := func(i, di, j, dj int) {
-		for i < m && j < n {
-			dfs(i, j)
-			i += di
-			j += dj
-		}
-	}
-
-	// search from the boundary
-	line(0, 0, 0, 1)   // top
-	line(m-1, 0, 0, 1) // down
-	line(0, 1, 0, 0)   // left
-	line(0, 1, n-1, 0) // right
-
-	res := 0
-	for i := 0; i < m; i++ {
-		for j := 0; j < n; j++ {
-			res += A[i][j]
-		}
-	}
-
-	return res
-}
diff --git a/problems/number-of-equal-count-substrings/README.md b/problems/number-of-equal-count-substrings/README.md
deleted file mode 100644
index 1b65042c0..000000000
--- a/problems/number-of-equal-count-substrings/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../account-balance "Account Balance")
-　　　　　　　　　　　　　　　　
-[Next >](../check-whether-two-strings-are-almost-equivalent "Check Whether Two Strings are Almost Equivalent")
-
-## [2067. Number of Equal Count Substrings (Medium)](https://leetcode.com/problems/number-of-equal-count-substrings "")
-
-
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The brute force solution is to check every substring, which would TLE. How can we improve this solution?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In an equal count substring, the first character appears count times, the second character appears count times, and so on.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The length of an equal count substring is the number of unique characters multiplied by count.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The length of all equal count substrings are multiples of count.
-</details>
diff --git a/problems/number-of-equivalent-domino-pairs/README.md b/problems/number-of-equivalent-domino-pairs/README.md
deleted file mode 100644
index 188b4d506..000000000
--- a/problems/number-of-equivalent-domino-pairs/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../user-purchase-platform "User Purchase Platform")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-path-with-alternating-colors "Shortest Path with Alternating Colors")
-
-## [1128. Number of Equivalent Domino Pairs (Easy)](https://leetcode.com/problems/number-of-equivalent-domino-pairs "等价多米诺骨牌对的数量")
-
-<p>Given a list of <code>dominoes</code>, <code>dominoes[i] = [a, b]</code> is <strong>equivalent to</strong> <code>dominoes[j] = [c, d]</code> if and only if either (<code>a == c</code> and <code>b == d</code>), or (<code>a == d</code> and <code>b == c</code>) - that is, one domino can be rotated to be equal to another domino.</p>
-
-<p>Return <em>the number of pairs </em><code>(i, j)</code><em> for which </em><code>0 &lt;= i &lt; j &lt; dominoes.length</code><em>, and </em><code>dominoes[i]</code><em> is <strong>equivalent to</strong> </em><code>dominoes[j]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> dominoes = [[1,2],[2,1],[3,4],[5,6]]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> dominoes = [[1,2],[1,2],[1,1],[1,2],[2,2]]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= dominoes.length &lt;= 4 * 10<sup>4</sup></code></li>
-	<li><code>dominoes[i].length == 2</code></li>
-	<li><code>1 &lt;= dominoes[i][j] &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each domino j, find the number of dominoes you've already seen (dominoes i with i < j) that are equivalent.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can keep track of what you've seen using a hashmap.
-</details>
diff --git a/problems/number-of-good-leaf-nodes-pairs/README.md b/problems/number-of-good-leaf-nodes-pairs/README.md
deleted file mode 100644
index d01430c7f..000000000
--- a/problems/number-of-good-leaf-nodes-pairs/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-suffix-flips "Minimum Suffix Flips")
-　　　　　　　　　　　　　　　　
-[Next >](../string-compression-ii "String Compression II")
-
-## [1530. Number of Good Leaf Nodes Pairs (Medium)](https://leetcode.com/problems/number-of-good-leaf-nodes-pairs "好叶子节点对的数量")
-
-<p>You are given the <code>root</code> of a binary tree and an integer <code>distance</code>. A pair of two different <strong>leaf</strong> nodes of a binary tree is said to be good if the length of <strong>the shortest path</strong> between them is less than or equal to <code>distance</code>.</p>
-
-<p>Return <em>the number of good leaf node pairs</em> in the tree.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/09/e1.jpg" style="width: 250px; height: 250px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,null,4], distance = 3
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The leaf nodes of the tree are 3 and 4 and the length of the shortest path between them is 3. This is the only good pair.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/09/e2.jpg" style="width: 250px; height: 182px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,6,7], distance = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The good pairs are [4,5] and [6,7] with shortest path = 2. The pair [4,6] is not good because the length of ther shortest path between them is 4.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [7,1,4,6,null,5,3,null,null,null,null,null,2], distance = 3
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only good pair is [2,5].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the <code>tree</code> is in the range <code>[1, 2<sup>10</sup>].</code></li>
-	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
-	<li><code>1 &lt;= distance &lt;= 10</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Start DFS from each leaf node. stop the DFS when the number of steps done > distance.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you reach another leaf node within distance steps, add 1 to the answer.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Note that all pairs will be counted twice so divide the answer by 2.
-</details>
diff --git a/problems/number-of-good-pairs/README.md b/problems/number-of-good-pairs/README.md
deleted file mode 100644
index f7631e3ce..000000000
--- a/problems/number-of-good-pairs/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../customer-order-frequency "Customer Order Frequency")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-substrings-with-only-1s "Number of Substrings With Only 1s")
-
-## [1512. Number of Good Pairs (Easy)](https://leetcode.com/problems/number-of-good-pairs "好数对的数目")
-
-<p>Given an array of integers <code>nums</code>, return <em>the number of <strong>good pairs</strong></em>.</p>
-
-<p>A pair <code>(i, j)</code> is called <em>good</em> if <code>nums[i] == nums[j]</code> and <code>i</code> &lt; <code>j</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,1,1,3]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are 4 good pairs (0,3), (0,4), (3,4), (2,5) 0-indexed.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,1]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Each pair in the array are <em>good</em>.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Number of Pairs of Interchangeable Rectangles](../number-of-pairs-of-interchangeable-rectangles) (Medium)
-  1. [Substrings That Begin and End With the Same Letter](../substrings-that-begin-and-end-with-the-same-letter) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count how many times each number appears. If a number appears n times, then n * (n – 1) // 2 good pairs can be made with this number.
-</details>
diff --git a/problems/number-of-good-ways-to-split-a-string/README.md b/problems/number-of-good-ways-to-split-a-string/README.md
deleted file mode 100644
index 39d75a7e4..000000000
--- a/problems/number-of-good-ways-to-split-a-string/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-sub-arrays-with-odd-sum "Number of Sub-arrays With Odd Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-increments-on-subarrays-to-form-a-target-array "Minimum Number of Increments on Subarrays to Form a Target Array")
-
-## [1525. Number of Good Ways to Split a String (Medium)](https://leetcode.com/problems/number-of-good-ways-to-split-a-string "字符串的好分割数目")
-
-<p>You are given a string <code>s</code>.</p>
-
-<p>A split is called <strong>good</strong> if you can split <code>s</code> into two non-empty strings <code>s<sub>left</sub></code> and <code>s<sub>right</sub></code> where their concatenation is equal to <code>s</code> (i.e., <code>s<sub>left</sub> + s<sub>right</sub> = s</code>) and the number of distinct letters in <code>s<sub>left</sub></code> and <code>s<sub>right</sub></code> is the same.</p>
-
-<p>Return <em>the number of <strong>good splits</strong> you can make in <code>s</code></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aacaba&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are 5 ways to split <code>&quot;aacaba&quot;</code> and 2 of them are good. 
-(&quot;a&quot;, &quot;acaba&quot;) Left string and right string contains 1 and 3 different letters respectively.
-(&quot;aa&quot;, &quot;caba&quot;) Left string and right string contains 1 and 3 different letters respectively.
-(&quot;aac&quot;, &quot;aba&quot;) Left string and right string contains 2 and 2 different letters respectively (good split).
-(&quot;aaca&quot;, &quot;ba&quot;) Left string and right string contains 2 and 2 different letters respectively (good split).
-(&quot;aacab&quot;, &quot;a&quot;) Left string and right string contains 3 and 1 different letters respectively.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcd&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Split the string as follows (&quot;ab&quot;, &quot;cd&quot;).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use two HashMap to store the counts of distinct letters in the left and right substring divided by the current index.
-</details>
diff --git a/problems/number-of-islands-ii/README.md b/problems/number-of-islands-ii/README.md
deleted file mode 100644
index d11faa469..000000000
--- a/problems/number-of-islands-ii/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-sum-query-2d-immutable "Range Sum Query 2D - Immutable")
-　　　　　　　　　　　　　　　　
-[Next >](../additive-number "Additive Number")
-
-## [305. Number of Islands II (Hard)](https://leetcode.com/problems/number-of-islands-ii "岛屿数量 II")
-
-<p>A 2d grid map of <code>m</code> rows and <code>n</code> columns is initially filled with water. We may perform an <i>addLand</i> operation which turns the water at position (row, col) into a land. Given a list of positions to operate, <b>count the number of islands after each <i>addLand</i> operation</b>. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-<b>Input:</b> m = 3, n = 3, positions = [[0,0], [0,1], [1,2], [2,1]]
-<b>Output:</b> [1,1,2,3]
-</pre>
-
-<p><b>Explanation:</b></p>
-
-<p>Initially, the 2d grid <code>grid</code> is filled with water. (Assume 0 represents water and 1 represents land).</p>
-
-<pre>
-0 0 0
-0 0 0
-0 0 0
-</pre>
-
-<p>Operation #1: addLand(0, 0) turns the water at grid[0][0] into a land.</p>
-
-<pre>
-1 0 0
-0 0 0   Number of islands = 1
-0 0 0
-</pre>
-
-<p>Operation #2: addLand(0, 1) turns the water at grid[0][1] into a land.</p>
-
-<pre>
-1 1 0
-0 0 0   Number of islands = 1
-0 0 0
-</pre>
-
-<p>Operation #3: addLand(1, 2) turns the water at grid[1][2] into a land.</p>
-
-<pre>
-1 1 0
-0 0 1   Number of islands = 2
-0 0 0
-</pre>
-
-<p>Operation #4: addLand(2, 1) turns the water at grid[2][1] into a land.</p>
-
-<pre>
-1 1 0
-0 0 1   Number of islands = 3
-0 1 0
-</pre>
-
-<p><b>Follow up:</b></p>
-
-<p>Can you do it in time complexity O(k log mn), where k is the length of the <code>positions</code>?</p>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Number of Islands](../number-of-islands) (Medium)
diff --git a/problems/number-of-islands-ii/number_of_islands_ii.go b/problems/number-of-islands-ii/number_of_islands_ii.go
deleted file mode 100644
index f9ddc34b9..000000000
--- a/problems/number-of-islands-ii/number_of_islands_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem305
diff --git a/problems/number-of-islands-ii/number_of_islands_ii_test.go b/problems/number-of-islands-ii/number_of_islands_ii_test.go
deleted file mode 100644
index f9ddc34b9..000000000
--- a/problems/number-of-islands-ii/number_of_islands_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem305
diff --git a/problems/number-of-islands/README.md b/problems/number-of-islands/README.md
deleted file mode 100644
index f0a9b1b79..000000000
--- a/problems/number-of-islands/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-right-side-view "Binary Tree Right Side View")
-　　　　　　　　　　　　　　　　
-[Next >](../bitwise-and-of-numbers-range "Bitwise AND of Numbers Range")
-
-## [200. Number of Islands (Medium)](https://leetcode.com/problems/number-of-islands "岛屿数量")
-
-<p>Given an <code>m x n</code> 2D binary grid <code>grid</code> which represents a map of <code>&#39;1&#39;</code>s (land) and <code>&#39;0&#39;</code>s (water), return <em>the number of islands</em>.</p>
-
-<p>An <strong>island</strong> is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [
-  [&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;0&quot;],
-  [&quot;1&quot;,&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;],
-  [&quot;1&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;],
-  [&quot;0&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;]
-]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [
-  [&quot;1&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;],
-  [&quot;1&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;],
-  [&quot;0&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;],
-  [&quot;0&quot;,&quot;0&quot;,&quot;0&quot;,&quot;1&quot;,&quot;1&quot;]
-]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 300</code></li>
-	<li><code>grid[i][j]</code> is <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Surrounded Regions](../surrounded-regions) (Medium)
-  1. [Walls and Gates](../walls-and-gates) (Medium)
-  1. [Number of Islands II](../number-of-islands-ii) (Hard)
-  1. [Number of Connected Components in an Undirected Graph](../number-of-connected-components-in-an-undirected-graph) (Medium)
-  1. [Number of Distinct Islands](../number-of-distinct-islands) (Medium)
-  1. [Max Area of Island](../max-area-of-island) (Medium)
diff --git a/problems/number-of-islands/number_of_islands.go b/problems/number-of-islands/number_of_islands.go
deleted file mode 100644
index cd42e2c11..000000000
--- a/problems/number-of-islands/number_of_islands.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem200
diff --git a/problems/number-of-islands/number_of_islands_test.go b/problems/number-of-islands/number_of_islands_test.go
deleted file mode 100644
index cd42e2c11..000000000
--- a/problems/number-of-islands/number_of_islands_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem200
diff --git a/problems/number-of-laser-beams-in-a-bank/README.md b/problems/number-of-laser-beams-in-a-bank/README.md
deleted file mode 100644
index 831713168..000000000
--- a/problems/number-of-laser-beams-in-a-bank/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-all-as-appears-before-all-bs "Check if All A's Appears Before All B's")
-　　　　　　　　　　　　　　　　
-[Next >](../destroying-asteroids "Destroying Asteroids")
-
-## [2125. Number of Laser Beams in a Bank (Medium)](https://leetcode.com/problems/number-of-laser-beams-in-a-bank "银行中的激光束数量")
-
-<p>Anti-theft security devices are activated inside a bank. You are given a <strong>0-indexed</strong> binary string array <code>bank</code> representing the floor plan of the bank, which is an <code>m x n</code> 2D matrix. <code>bank[i]</code> represents the <code>i<sup>th</sup></code> row, consisting of <code>&#39;0&#39;</code>s and <code>&#39;1&#39;</code>s. <code>&#39;0&#39;</code> means the cell is empty, while<code>&#39;1&#39;</code> means the cell has a security device.</p>
-
-<p>There is <strong>one</strong> laser beam between any <strong>two</strong> security devices <strong>if both</strong> conditions are met:</p>
-
-<ul>
-	<li>The two devices are located on two <strong>different rows</strong>: <code>r<sub>1</sub></code> and <code>r<sub>2</sub></code>, where <code>r<sub>1</sub> &lt; r<sub>2</sub></code>.</li>
-	<li>For <strong>each</strong> row <code>i</code> where <code>r<sub>1</sub> &lt; i &lt; r<sub>2</sub></code>, there are <strong>no security devices</strong> in the <code>i<sup>th</sup></code> row.</li>
-</ul>
-
-<p>Laser beams are independent, i.e., one beam does not interfere nor join with another.</p>
-
-<p>Return <em>the total number of laser beams in the bank</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/24/laser1.jpg" style="width: 400px; height: 368px;" />
-<pre>
-<strong>Input:</strong> bank = [&quot;011001&quot;,&quot;000000&quot;,&quot;010100&quot;,&quot;001000&quot;]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> Between each of the following device pairs, there is one beam. In total, there are 8 beams:
- * bank[0][1] -- bank[2][1]
- * bank[0][1] -- bank[2][3]
- * bank[0][2] -- bank[2][1]
- * bank[0][2] -- bank[2][3]
- * bank[0][5] -- bank[2][1]
- * bank[0][5] -- bank[2][3]
- * bank[2][1] -- bank[3][2]
- * bank[2][3] -- bank[3][2]
-Note that there is no beam between any device on the 0<sup>th</sup> row with any on the 3<sup>rd</sup> row.
-This is because the 2<sup>nd</sup> row contains security devices, which breaks the second condition.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/24/laser2.jpg" style="width: 244px; height: 325px;" />
-<pre>
-<strong>Input:</strong> bank = [&quot;000&quot;,&quot;111&quot;,&quot;000&quot;]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There does not exist two devices located on two different rows.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == bank.length</code></li>
-	<li><code>n == bank[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 500</code></li>
-	<li><code>bank[i][j]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What is the commonality between security devices on the same row?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Each device on the same row has the same number of beams pointing towards the devices on the next row with devices.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If you were given an integer array where each element is the number of security devices on each row, can you solve it?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Convert the input to such an array, skip any row with no security device, then find the sum of the product between adjacent elements.
-</details>
diff --git a/problems/number-of-lines-to-write-string/README.md b/problems/number-of-lines-to-write-string/README.md
deleted file mode 100644
index c21fe3637..000000000
--- a/problems/number-of-lines-to-write-string/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-array-with-same-average "Split Array With Same Average")
-　　　　　　　　　　　　　　　　
-[Next >](../max-increase-to-keep-city-skyline "Max Increase to Keep City Skyline")
-
-## [806. Number of Lines To Write String (Easy)](https://leetcode.com/problems/number-of-lines-to-write-string "写字符串需要的行数")
-
-<p>You are given a string <code>s</code> of lowercase English letters and an array <code>widths</code> denoting <strong>how many pixels wide</strong> each lowercase English letter is. Specifically, <code>widths[0]</code> is the width of <code>&#39;a&#39;</code>, <code>widths[1]</code> is the width of <code>&#39;b&#39;</code>, and so on.</p>
-
-<p>You are trying to write <code>s</code> across several lines, where <strong>each line is no longer than </strong><code>100</code><strong> pixels</strong>. Starting at the beginning of <code>s</code>, write as many letters on the first line such that the total width does not exceed <code>100</code> pixels. Then, from where you stopped in <code>s</code>, continue writing as many letters as you can on the second line. Continue this process until you have written all of <code>s</code>.</p>
-
-<p>Return <em>an array </em><code>result</code><em> of length 2 where:</em></p>
-
-<ul>
-	<li><code>result[0]</code><em> is the total number of lines.</em></li>
-	<li><code>result[1]</code><em> is the width of the last line in pixels.</em></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> widths = [10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10], s = &quot;abcdefghijklmnopqrstuvwxyz&quot;
-<strong>Output:</strong> [3,60]
-<strong>Explanation:</strong> You can write s as follows:
-abcdefghij  // 100 pixels wide
-klmnopqrst  // 100 pixels wide
-uvwxyz      // 60 pixels wide
-There are a total of 3 lines, and the last line is 60 pixels wide.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> widths = [4,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10], s = &quot;bbbcccdddaaa&quot;
-<strong>Output:</strong> [2,4]
-<strong>Explanation:</strong> You can write s as follows:
-bbbcccdddaa  // 98 pixels wide
-a            // 4 pixels wide
-There are a total of 2 lines, and the last line is 4 pixels wide.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>widths.length == 26</code></li>
-	<li><code>2 &lt;= widths[i] &lt;= 10</code></li>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/number-of-lines-to-write-string/number_of_lines_to_write_string.go b/problems/number-of-lines-to-write-string/number_of_lines_to_write_string.go
deleted file mode 100644
index 016703357..000000000
--- a/problems/number-of-lines-to-write-string/number_of_lines_to_write_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem806
diff --git a/problems/number-of-lines-to-write-string/number_of_lines_to_write_string_test.go b/problems/number-of-lines-to-write-string/number_of_lines_to_write_string_test.go
deleted file mode 100644
index 016703357..000000000
--- a/problems/number-of-lines-to-write-string/number_of_lines_to_write_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem806
diff --git a/problems/number-of-longest-increasing-subsequence/README.md b/problems/number-of-longest-increasing-subsequence/README.md
deleted file mode 100644
index b3431dc6c..000000000
--- a/problems/number-of-longest-increasing-subsequence/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bulb-switcher-ii "Bulb Switcher II")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-continuous-increasing-subsequence "Longest Continuous Increasing Subsequence")
-
-## [673. Number of Longest Increasing Subsequence (Medium)](https://leetcode.com/problems/number-of-longest-increasing-subsequence "最长递增子序列的个数")
-
-<p>Given an integer array&nbsp;<code>nums</code>, return <em>the number of longest increasing subsequences.</em></p>
-
-<p><strong>Notice</strong> that the sequence has to be <strong>strictly</strong> increasing.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,5,4,7]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The two longest increasing subsequences are [1, 3, 4, 7] and [1, 3, 5, 7].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,2,2,2]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The length of longest continuous increasing subsequence is 1, and there are 5 subsequences&#39; length is 1, so output 5.
-
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2000</code></li>
-	<li><code>-10<sup>6</sup> &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-
-### Similar Questions
-  1. [Longest Increasing Subsequence](../longest-increasing-subsequence) (Medium)
-  1. [Longest Continuous Increasing Subsequence](../longest-continuous-increasing-subsequence) (Easy)
diff --git a/problems/number-of-longest-increasing-subsequence/number_of_longest_increasing_subsequence.go b/problems/number-of-longest-increasing-subsequence/number_of_longest_increasing_subsequence.go
deleted file mode 100644
index 70510e1ef..000000000
--- a/problems/number-of-longest-increasing-subsequence/number_of_longest_increasing_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem673
diff --git a/problems/number-of-longest-increasing-subsequence/number_of_longest_increasing_subsequence_test.go b/problems/number-of-longest-increasing-subsequence/number_of_longest_increasing_subsequence_test.go
deleted file mode 100644
index 70510e1ef..000000000
--- a/problems/number-of-longest-increasing-subsequence/number_of_longest_increasing_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem673
diff --git a/problems/number-of-matching-subsequences/README.md b/problems/number-of-matching-subsequences/README.md
deleted file mode 100644
index b9a9e5cd2..000000000
--- a/problems/number-of-matching-subsequences/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../custom-sort-string "Custom Sort String")
-　　　　　　　　　　　　　　　　
-[Next >](../preimage-size-of-factorial-zeroes-function "Preimage Size of Factorial Zeroes Function")
-
-## [792. Number of Matching Subsequences (Medium)](https://leetcode.com/problems/number-of-matching-subsequences "匹配子序列的单词数")
-
-<p>Given a string <code>s</code> and an array of strings <code>words</code>, return <em>the number of</em> <code>words[i]</code> <em>that is a subsequence of</em> <code>s</code>.</p>
-
-<p>A <strong>subsequence</strong> of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.</p>
-
-<ul>
-	<li>For example, <code>&quot;ace&quot;</code> is a subsequence of <code>&quot;abcde&quot;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcde&quot;, words = [&quot;a&quot;,&quot;bb&quot;,&quot;acd&quot;,&quot;ace&quot;]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> There are three strings in words that are a subsequence of s: &quot;a&quot;, &quot;acd&quot;, &quot;ace&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;dsahjpjauf&quot;, words = [&quot;ahjpjau&quot;,&quot;ja&quot;,&quot;ahbwzgqnuk&quot;,&quot;tnmlanowax&quot;]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= words.length &lt;= 5000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 50</code></li>
-	<li><code>s</code> and <code>words[i]</code> consist of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Is Subsequence](../is-subsequence) (Easy)
diff --git a/problems/number-of-matching-subsequences/number_of_matching_subsequences.go b/problems/number-of-matching-subsequences/number_of_matching_subsequences.go
deleted file mode 100644
index cbe44df7f..000000000
--- a/problems/number-of-matching-subsequences/number_of_matching_subsequences.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem792
diff --git a/problems/number-of-matching-subsequences/number_of_matching_subsequences_test.go b/problems/number-of-matching-subsequences/number_of_matching_subsequences_test.go
deleted file mode 100644
index cbe44df7f..000000000
--- a/problems/number-of-matching-subsequences/number_of_matching_subsequences_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem792
diff --git a/problems/number-of-music-playlists/README.md b/problems/number-of-music-playlists/README.md
deleted file mode 100644
index 7560a9845..000000000
--- a/problems/number-of-music-playlists/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../complete-binary-tree-inserter "Complete Binary Tree Inserter")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-add-to-make-parentheses-valid "Minimum Add to Make Parentheses Valid")
-
-## [920. Number of Music Playlists (Hard)](https://leetcode.com/problems/number-of-music-playlists "播放列表的数量")
-
-<p>Your music player contains <code>n</code> different songs. You want to listen to <code>goal</code> songs (not necessarily different) during your trip. To avoid boredom, you will create a playlist so that:</p>
-
-<ul>
-	<li>Every song is played <strong>at least once</strong>.</li>
-	<li>A song can only be played again only if <code>k</code> other songs have been played.</li>
-</ul>
-
-<p>Given <code>n</code>, <code>goal</code>, and <code>k</code>, return <em>the number of possible playlists that you can create</em>. Since the answer can be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, goal = 3, k = 1
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> There are 6 possible playlists: [1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], and [3, 2, 1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, goal = 3, k = 0
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> There are 6 possible playlists: [1, 1, 2], [1, 2, 1], [2, 1, 1], [2, 2, 1], [2, 1, 2], and [1, 2, 2].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, goal = 3, k = 1
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are 2 possible playlists: [1, 2, 1] and [2, 1, 2].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= k &lt; n &lt;= goal &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
diff --git a/problems/number-of-music-playlists/number_of_music_playlists.go b/problems/number-of-music-playlists/number_of_music_playlists.go
deleted file mode 100644
index 091dcd6ce..000000000
--- a/problems/number-of-music-playlists/number_of_music_playlists.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem920
diff --git a/problems/number-of-music-playlists/number_of_music_playlists_test.go b/problems/number-of-music-playlists/number_of_music_playlists_test.go
deleted file mode 100644
index 091dcd6ce..000000000
--- a/problems/number-of-music-playlists/number_of_music_playlists_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem920
diff --git a/problems/number-of-nodes-in-the-sub-tree-with-the-same-label/README.md b/problems/number-of-nodes-in-the-sub-tree-with-the-same-label/README.md
deleted file mode 100644
index fbfb6a7ef..000000000
--- a/problems/number-of-nodes-in-the-sub-tree-with-the-same-label/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../water-bottles "Water Bottles")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-non-overlapping-substrings "Maximum Number of Non-Overlapping Substrings")
-
-## [1519. Number of Nodes in the Sub-Tree With the Same Label (Medium)](https://leetcode.com/problems/number-of-nodes-in-the-sub-tree-with-the-same-label "子树中标签相同的节点数")
-
-<p>You are given a tree (i.e. a connected, undirected graph that has no cycles) consisting of <code>n</code> nodes numbered from <code>0</code> to <code>n - 1</code> and exactly <code>n - 1</code> <code>edges</code>. The <strong>root</strong> of the tree is the node <code>0</code>, and each node of the tree has <strong>a label</strong> which is a lower-case character given in the string <code>labels</code> (i.e. The node with the number <code>i</code> has the label <code>labels[i]</code>).</p>
-
-<p>The <code>edges</code> array is given on the form <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code>, which means there is an edge between nodes <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code> in the tree.</p>
-
-<p>Return <em>an array of size <code>n</code></em> where <code>ans[i]</code> is the number of nodes in the subtree of the <code>i<sup>th</sup></code> node which have the same label as node <code>i</code>.</p>
-
-<p>A subtree of a tree <code>T</code> is the tree consisting of a node in <code>T</code> and all of its descendant nodes.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/01/q3e1.jpg" style="width: 400px; height: 291px;" />
-<pre>
-<strong>Input:</strong> n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], labels = &quot;abaedcd&quot;
-<strong>Output:</strong> [2,1,1,1,1,1,1]
-<strong>Explanation:</strong> Node 0 has label &#39;a&#39; and its sub-tree has node 2 with label &#39;a&#39; as well, thus the answer is 2. Notice that any node is part of its sub-tree.
-Node 1 has a label &#39;b&#39;. The sub-tree of node 1 contains nodes 1,4 and 5, as nodes 4 and 5 have different labels than node 1, the answer is just 1 (the node itself).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/01/q3e2.jpg" style="width: 300px; height: 253px;" />
-<pre>
-<strong>Input:</strong> n = 4, edges = [[0,1],[1,2],[0,3]], labels = &quot;bbbb&quot;
-<strong>Output:</strong> [4,2,1,1]
-<strong>Explanation:</strong> The sub-tree of node 2 contains only node 2, so the answer is 1.
-The sub-tree of node 3 contains only node 3, so the answer is 1.
-The sub-tree of node 1 contains nodes 1 and 2, both have label &#39;b&#39;, thus the answer is 2.
-The sub-tree of node 0 contains nodes 0, 1, 2 and 3, all with label &#39;b&#39;, thus the answer is 4.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/01/q3e3.jpg" style="width: 300px; height: 253px;" />
-<pre>
-<strong>Input:</strong> n = 5, edges = [[0,1],[0,2],[1,3],[0,4]], labels = &quot;aabab&quot;
-<strong>Output:</strong> [3,2,1,1,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>edges.length == n - 1</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt; n</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-	<li><code>labels.length == n</code></li>
-	<li><code>labels</code> is consisting of only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Start traversing the tree and each node should return a vector to its parent node.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The vector should be of length 26 and have the count of all the labels in the sub-tree of this node.
-</details>
diff --git a/problems/number-of-operations-to-make-network-connected/README.md b/problems/number-of-operations-to-make-network-connected/README.md
deleted file mode 100644
index 77fb4cf07..000000000
--- a/problems/number-of-operations-to-make-network-connected/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-flips-to-make-a-or-b-equal-to-c "Minimum Flips to Make a OR b Equal to c")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-distance-to-type-a-word-using-two-fingers "Minimum Distance to Type a Word Using Two Fingers")
-
-## [1319. Number of Operations to Make Network Connected (Medium)](https://leetcode.com/problems/number-of-operations-to-make-network-connected "连通网络的操作次数")
-
-<p>There are <code>n</code> computers numbered from <code>0</code> to <code>n - 1</code> connected by ethernet cables <code>connections</code> forming a network where <code>connections[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> represents a connection between computers <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code>. Any computer can reach any other computer directly or indirectly through the network.</p>
-
-<p>You are given an initial computer network <code>connections</code>. You can extract certain cables between two directly connected computers, and place them between any pair of disconnected computers to make them directly connected.</p>
-
-<p>Return <em>the minimum number of times you need to do this in order to make all the computers connected</em>. If it is not possible, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/02/sample_1_1677.png" style="width: 500px; height: 148px;" />
-<pre>
-<strong>Input:</strong> n = 4, connections = [[0,1],[0,2],[1,2]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Remove cable between computer 1 and 2 and place between computers 1 and 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/02/sample_2_1677.png" style="width: 500px; height: 129px;" />
-<pre>
-<strong>Input:</strong> n = 6, connections = [[0,1],[0,2],[0,3],[1,2],[1,3]]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6, connections = [[0,1],[0,2],[0,3],[1,2]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There are not enough cables.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= connections.length &lt;= min(n * (n - 1) / 2, 10<sup>5</sup>)</code></li>
-	<li><code>connections[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt; n</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-	<li>There are no repeated connections.</li>
-	<li>No two computers are connected by more than one cable.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-As long as there are at least (n - 1) connections, there is definitely a way to connect all computers.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use DFS to determine the number of isolated computer clusters.
-</details>
diff --git a/problems/number-of-orders-in-the-backlog/README.md b/problems/number-of-orders-in-the-backlog/README.md
deleted file mode 100644
index dcfcdfae9..000000000
--- a/problems/number-of-orders-in-the-backlog/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-ascending-subarray-sum "Maximum Ascending Subarray Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-value-at-a-given-index-in-a-bounded-array "Maximum Value at a Given Index in a Bounded Array")
-
-## [1801. Number of Orders in the Backlog (Medium)](https://leetcode.com/problems/number-of-orders-in-the-backlog "积压订单中的订单总数")
-
-<p>You are given a 2D integer array <code>orders</code>, where each <code>orders[i] = [price<sub>i</sub>, amount<sub>i</sub>, orderType<sub>i</sub>]</code> denotes that <code>amount<sub>i</sub></code><sub> </sub>orders have been placed of type <code>orderType<sub>i</sub></code> at the price <code>price<sub>i</sub></code>. The <code>orderType<sub>i</sub></code> is:</p>
-
-<ul>
-	<li><code>0</code> if it is a batch of <code>buy</code> orders, or</li>
-	<li><code>1</code> if it is a batch of <code>sell</code> orders.</li>
-</ul>
-
-<p>Note that <code>orders[i]</code> represents a batch of <code>amount<sub>i</sub></code> independent orders with the same price and order type. All orders represented by <code>orders[i]</code> will be placed before all orders represented by <code>orders[i+1]</code> for all valid <code>i</code>.</p>
-
-<p>There is a <strong>backlog</strong> that consists of orders that have not been executed. The backlog is initially empty. When an order is placed, the following happens:</p>
-
-<ul>
-	<li>If the order is a <code>buy</code> order, you look at the <code>sell</code> order with the <strong>smallest</strong> price in the backlog. If that <code>sell</code> order&#39;s price is <strong>smaller than or equal to</strong> the current <code>buy</code> order&#39;s price, they will match and be executed, and that <code>sell</code> order will be removed from the backlog. Else, the <code>buy</code> order is added to the backlog.</li>
-	<li>Vice versa, if the order is a <code>sell</code> order, you look at the <code>buy</code> order with the <strong>largest</strong> price in the backlog. If that <code>buy</code> order&#39;s price is <strong>larger than or equal to</strong> the current <code>sell</code> order&#39;s price, they will match and be executed, and that <code>buy</code> order will be removed from the backlog. Else, the <code>sell</code> order is added to the backlog.</li>
-</ul>
-
-<p>Return <em>the total <strong>amount</strong> of orders in the backlog after placing all the orders from the input</em>. Since this number can be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/11/ex1.png" style="width: 450px; height: 479px;" />
-<pre>
-<strong>Input:</strong> orders = [[10,5,0],[15,2,1],[25,1,1],[30,4,0]]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Here is what happens with the orders:
-- 5 orders of type buy with price 10 are placed. There are no sell orders, so the 5 orders are added to the backlog.
-- 2 orders of type sell with price 15 are placed. There are no buy orders with prices larger than or equal to 15, so the 2 orders are added to the backlog.
-- 1 order of type sell with price 25 is placed. There are no buy orders with prices larger than or equal to 25 in the backlog, so this order is added to the backlog.
-- 4 orders of type buy with price 30 are placed. The first 2 orders are matched with the 2 sell orders of the least price, which is 15 and these 2 sell orders are removed from the backlog. The 3<sup>rd</sup> order is matched with the sell order of the least price, which is 25 and this sell order is removed from the backlog. Then, there are no more sell orders in the backlog, so the 4<sup>th</sup> order is added to the backlog.
-Finally, the backlog has 5 buy orders with price 10, and 1 buy order with price 30. So the total number of orders in the backlog is 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/11/ex2.png" style="width: 450px; height: 584px;" />
-<pre>
-<strong>Input:</strong> orders = [[7,1000000000,1],[15,3,0],[5,999999995,0],[5,1,1]]
-<strong>Output:</strong> 999999984
-<strong>Explanation:</strong> Here is what happens with the orders:
-- 10<sup>9</sup> orders of type sell with price 7 are placed. There are no buy orders, so the 10<sup>9</sup> orders are added to the backlog.
-- 3 orders of type buy with price 15 are placed. They are matched with the 3 sell orders with the least price which is 7, and those 3 sell orders are removed from the backlog.
-- 999999995 orders of type buy with price 5 are placed. The least price of a sell order is 7, so the 999999995 orders are added to the backlog.
-- 1 order of type sell with price 5 is placed. It is matched with the buy order of the highest price, which is 5, and that buy order is removed from the backlog.
-Finally, the backlog has (1000000000-3) sell orders with price 7, and (999999995-1) buy orders with price 5. So the total number of orders = 1999999991, which is equal to 999999984 % (10<sup>9</sup> + 7).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= orders.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>orders[i].length == 3</code></li>
-	<li><code>1 &lt;= price<sub>i</sub>, amount<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>orderType<sub>i</sub></code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Store the backlog buy and sell orders in two heaps, the buy orders in a max heap by price and the sell orders in a min heap by price.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Store the orders in batches and update the fields according to new incoming orders. Each batch should only take 1 "slot" in the heap.
-</details>
diff --git a/problems/number-of-pairs-of-interchangeable-rectangles/README.md b/problems/number-of-pairs-of-interchangeable-rectangles/README.md
deleted file mode 100644
index c03ce8bca..000000000
--- a/problems/number-of-pairs-of-interchangeable-rectangles/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-prefix-of-word "Reverse Prefix of Word")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-product-of-the-length-of-two-palindromic-subsequences "Maximum Product of the Length of Two Palindromic Subsequences")
-
-## [2001. Number of Pairs of Interchangeable Rectangles (Medium)](https://leetcode.com/problems/number-of-pairs-of-interchangeable-rectangles "可互换矩形的组数")
-
-<p>You are given <code>n</code> rectangles represented by a <strong>0-indexed</strong> 2D integer array <code>rectangles</code>, where <code>rectangles[i] = [width<sub>i</sub>, height<sub>i</sub>]</code> denotes the width and height of the <code>i<sup>th</sup></code> rectangle.</p>
-
-<p>Two rectangles <code>i</code> and <code>j</code> (<code>i &lt; j</code>) are considered <strong>interchangeable</strong> if they have the <strong>same</strong> width-to-height ratio. More formally, two rectangles are <strong>interchangeable</strong> if <code>width<sub>i</sub>/height<sub>i</sub> == width<sub>j</sub>/height<sub>j</sub></code> (using decimal division, not integer division).</p>
-
-<p>Return <em>the <strong>number</strong> of pairs of <strong>interchangeable</strong> rectangles in </em><code>rectangles</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rectangles = [[4,8],[3,6],[10,20],[15,30]]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The following are the interchangeable pairs of rectangles by index (0-indexed):
-- Rectangle 0 with rectangle 1: 4/8 == 3/6.
-- Rectangle 0 with rectangle 2: 4/8 == 10/20.
-- Rectangle 0 with rectangle 3: 4/8 == 15/30.
-- Rectangle 1 with rectangle 2: 3/6 == 10/20.
-- Rectangle 1 with rectangle 3: 3/6 == 15/30.
-- Rectangle 2 with rectangle 3: 10/20 == 15/30.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rectangles = [[4,5],[7,8]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no interchangeable pairs of rectangles.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == rectangles.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>rectangles[i].length == 2</code></li>
-	<li><code>1 &lt;= width<sub>i</sub>, height<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Number Theory](../../tag/number-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Store the rectangle height and width ratio in a hashmap.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Traverse the ratios, and for each ratio, use the frequency of the ratio to add to the total pair count.
-</details>
diff --git a/problems/number-of-pairs-of-strings-with-concatenation-equal-to-target/README.md b/problems/number-of-pairs-of-strings-with-concatenation-equal-to-target/README.md
deleted file mode 100644
index 07acd4a01..000000000
--- a/problems/number-of-pairs-of-strings-with-concatenation-equal-to-target/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-1d-array-into-2d-array "Convert 1D Array Into 2D Array")
-　　　　　　　　　　　　　　　　
-[Next >](../maximize-the-confusion-of-an-exam "Maximize the Confusion of an Exam")
-
-## [2023. Number of Pairs of Strings With Concatenation Equal to Target (Medium)](https://leetcode.com/problems/number-of-pairs-of-strings-with-concatenation-equal-to-target "连接后等于目标字符串的字符串对")
-
-<p>Given an array of <strong>digit</strong> strings <code>nums</code> and a <strong>digit</strong> string <code>target</code>, return <em>the number of pairs of indices </em><code>(i, j)</code><em> (where </em><code>i != j</code><em>) such that the <strong>concatenation</strong> of </em><code>nums[i] + nums[j]</code><em> equals </em><code>target</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [&quot;777&quot;,&quot;7&quot;,&quot;77&quot;,&quot;77&quot;], target = &quot;7777&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Valid pairs are:
-- (0, 1): &quot;777&quot; + &quot;7&quot;
-- (1, 0): &quot;7&quot; + &quot;777&quot;
-- (2, 3): &quot;77&quot; + &quot;77&quot;
-- (3, 2): &quot;77&quot; + &quot;77&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [&quot;123&quot;,&quot;4&quot;,&quot;12&quot;,&quot;34&quot;], target = &quot;1234&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Valid pairs are:
-- (0, 1): &quot;123&quot; + &quot;4&quot;
-- (2, 3): &quot;12&quot; + &quot;34&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [&quot;1&quot;,&quot;1&quot;,&quot;1&quot;], target = &quot;11&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Valid pairs are:
-- (0, 1): &quot;1&quot; + &quot;1&quot;
-- (1, 0): &quot;1&quot; + &quot;1&quot;
-- (0, 2): &quot;1&quot; + &quot;1&quot;
-- (2, 0): &quot;1&quot; + &quot;1&quot;
-- (1, 2): &quot;1&quot; + &quot;1&quot;
-- (2, 1): &quot;1&quot; + &quot;1&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>1 &lt;= nums[i].length &lt;= 100</code></li>
-	<li><code>2 &lt;= target.length &lt;= 100</code></li>
-	<li><code>nums[i]</code> and <code>target</code> consist of digits.</li>
-	<li><code>nums[i]</code> and <code>target</code> do not have leading zeros.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to concatenate every two different strings from the list.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Count the number of pairs with concatenation equals to target.
-</details>
diff --git a/problems/number-of-paths-with-max-score/README.md b/problems/number-of-paths-with-max-score/README.md
deleted file mode 100644
index 773e71630..000000000
--- a/problems/number-of-paths-with-max-score/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-mutated-array-closest-to-target "Sum of Mutated Array Closest to Target")
-　　　　　　　　　　　　　　　　
-[Next >](../deepest-leaves-sum "Deepest Leaves Sum")
-
-## [1301. Number of Paths with Max Score (Hard)](https://leetcode.com/problems/number-of-paths-with-max-score "最大得分的路径数目")
-
-<p>You are given a square <code>board</code>&nbsp;of characters. You can move on the board starting at the bottom right square marked with the character&nbsp;<code>&#39;S&#39;</code>.</p>
-
-<p>You need&nbsp;to reach the top left square marked with the character <code>&#39;E&#39;</code>. The rest of the squares are labeled either with a numeric character&nbsp;<code>1, 2, ..., 9</code> or with an obstacle <code>&#39;X&#39;</code>. In one move you can go up, left or up-left (diagonally) only if there is no obstacle there.</p>
-
-<p>Return a list of two integers: the first integer is the maximum sum of numeric characters you can collect, and the second is the number of such paths that you can take to get that maximum sum, <strong>taken modulo <code>10^9 + 7</code></strong>.</p>
-
-<p>In case there is no path, return&nbsp;<code>[0, 0]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> board = ["E23","2X2","12S"]
-<strong>Output:</strong> [7,1]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> board = ["E12","1X1","21S"]
-<strong>Output:</strong> [4,2]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> board = ["E11","XXX","11S"]
-<strong>Output:</strong> [0,0]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= board.length == board[i].length &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming to find the path with the max score.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use another dynamic programming array to count the number of paths with max score.
-</details>
diff --git a/problems/number-of-provinces/README.md b/problems/number-of-provinces/README.md
deleted file mode 100644
index e55fc5326..000000000
--- a/problems/number-of-provinces/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-boxes "Remove Boxes")
-　　　　　　　　　　　　　　　　
-[Next >](../split-array-with-equal-sum "Split Array with Equal Sum")
-
-## [547. Number of Provinces (Medium)](https://leetcode.com/problems/number-of-provinces "省份数量")
-
-<p>There are <code>n</code> cities. Some of them are connected, while some are not. If city <code>a</code> is connected directly with city <code>b</code>, and city <code>b</code> is connected directly with city <code>c</code>, then city <code>a</code> is connected indirectly with city <code>c</code>.</p>
-
-<p>A <strong>province</strong> is a group of directly or indirectly connected cities and no other cities outside of the group.</p>
-
-<p>You are given an <code>n x n</code> matrix <code>isConnected</code> where <code>isConnected[i][j] = 1</code> if the <code>i<sup>th</sup></code> city and the <code>j<sup>th</sup></code> city are directly connected, and <code>isConnected[i][j] = 0</code> otherwise.</p>
-
-<p>Return <em>the total number of <strong>provinces</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/24/graph1.jpg" style="width: 222px; height: 142px;" />
-<pre>
-<strong>Input:</strong> isConnected = [[1,1,0],[1,1,0],[0,0,1]]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/24/graph2.jpg" style="width: 222px; height: 142px;" />
-<pre>
-<strong>Input:</strong> isConnected = [[1,0,0],[0,1,0],[0,0,1]]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 200</code></li>
-	<li><code>n == isConnected.length</code></li>
-	<li><code>n == isConnected[i].length</code></li>
-	<li><code>isConnected[i][j]</code> is <code>1</code> or <code>0</code>.</li>
-	<li><code>isConnected[i][i] == 1</code></li>
-	<li><code>isConnected[i][j] == isConnected[j][i]</code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [Number of Connected Components in an Undirected Graph](../number-of-connected-components-in-an-undirected-graph) (Medium)
-  1. [Robot Return to Origin](../robot-return-to-origin) (Easy)
-  1. [Sentence Similarity](../sentence-similarity) (Easy)
-  1. [Sentence Similarity II](../sentence-similarity-ii) (Medium)
-  1. [The Earliest Moment When Everyone Become Friends](../the-earliest-moment-when-everyone-become-friends) (Medium)
diff --git a/problems/number-of-recent-calls/README.md b/problems/number-of-recent-calls/README.md
deleted file mode 100644
index d961559a0..000000000
--- a/problems/number-of-recent-calls/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../beautiful-array "Beautiful Array")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-bridge "Shortest Bridge")
-
-## [933. Number of Recent Calls (Easy)](https://leetcode.com/problems/number-of-recent-calls "最近的请求次数")
-
-<p>You have a <code>RecentCounter</code> class which counts the number of recent requests within a certain time frame.</p>
-
-<p>Implement the <code>RecentCounter</code> class:</p>
-
-<ul>
-	<li><code>RecentCounter()</code> Initializes the counter with zero recent requests.</li>
-	<li><code>int ping(int t)</code> Adds a new request at time <code>t</code>, where <code>t</code> represents some time in milliseconds, and returns the number of requests that has happened in the past <code>3000</code> milliseconds (including the new request). Specifically, return the number of requests that have happened in the inclusive range <code>[t - 3000, t]</code>.</li>
-</ul>
-
-<p>It is <strong>guaranteed</strong> that every call to <code>ping</code> uses a strictly larger value of <code>t</code> than the previous call.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;RecentCounter&quot;, &quot;ping&quot;, &quot;ping&quot;, &quot;ping&quot;, &quot;ping&quot;]
-[[], [1], [100], [3001], [3002]]
-<strong>Output</strong>
-[null, 1, 2, 3, 3]
-
-<strong>Explanation</strong>
-RecentCounter recentCounter = new RecentCounter();
-recentCounter.ping(1);     // requests = [<u>1</u>], range is [-2999,1], return 1
-recentCounter.ping(100);   // requests = [<u>1</u>, <u>100</u>], range is [-2900,100], return 2
-recentCounter.ping(3001);  // requests = [<u>1</u>, <u>100</u>, <u>3001</u>], range is [1,3001], return 3
-recentCounter.ping(3002);  // requests = [1, <u>100</u>, <u>3001</u>, <u>3002</u>], range is [2,3002], return 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= t &lt;= 10<sup>9</sup></code></li>
-	<li>Each test case will call <code>ping</code> with <strong>strictly increasing</strong> values of <code>t</code>.</li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>ping</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
diff --git a/problems/number-of-recent-calls/number_of_recent_calls.go b/problems/number-of-recent-calls/number_of_recent_calls.go
deleted file mode 100644
index 5202162ce..000000000
--- a/problems/number-of-recent-calls/number_of_recent_calls.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem933
-
-import "container/list"
-
-type RecentCounter struct {
-	queue *list.List
-}
-
-func Constructor() RecentCounter {
-	return RecentCounter{list.New()}
-}
-
-func (this *RecentCounter) Ping(t int) int {
-	this.queue.PushBack(t)
-	for this.queue.Front().Value.(int) < t-3000 {
-		this.queue.Remove(this.queue.Front())
-	}
-	return this.queue.Len()
-}
-
-/**
- * Your RecentCounter object will be instantiated and called as such:
- * obj := Constructor();
- * param_1 := obj.Ping(t);
- */
diff --git a/problems/number-of-recent-calls/number_of_recent_calls_test.go b/problems/number-of-recent-calls/number_of_recent_calls_test.go
deleted file mode 100644
index 8cee8bc23..000000000
--- a/problems/number-of-recent-calls/number_of_recent_calls_test.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem933
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestConstructor(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 100, 3001, 3002},
-			want: []int{1, 2, 3, 3},
-		},
-	}
-	for _, tt := range tests {
-		obj, got := Constructor(), make([]int, 0)
-		for _, t := range tt.in {
-			got = append(got, obj.Ping(t))
-		}
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/number-of-rectangles-that-can-form-the-largest-square/README.md b/problems/number-of-rectangles-that-can-form-the-largest-square/README.md
deleted file mode 100644
index 4e1dbdfa1..000000000
--- a/problems/number-of-rectangles-that-can-form-the-largest-square/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../checking-existence-of-edge-length-limited-paths-ii "Checking Existence of Edge Length Limited Paths II")
-　　　　　　　　　　　　　　　　
-[Next >](../tuple-with-same-product "Tuple with Same Product")
-
-## [1725. Number Of Rectangles That Can Form The Largest Square (Easy)](https://leetcode.com/problems/number-of-rectangles-that-can-form-the-largest-square "可以形成最大正方形的矩形数目")
-
-<p>You are given an array <code>rectangles</code> where <code>rectangles[i] = [l<sub>i</sub>, w<sub>i</sub>]</code> represents the <code>i<sup>th</sup></code> rectangle of length <code>l<sub>i</sub></code> and width <code>w<sub>i</sub></code>.</p>
-
-<p>You can cut the <code>i<sup>th</sup></code> rectangle to form a square with a side length of <code>k</code> if both <code>k &lt;= l<sub>i</sub></code> and <code>k &lt;= w<sub>i</sub></code>. For example, if you have a rectangle <code>[4,6]</code>, you can cut it to get a square with a side length of at most <code>4</code>.</p>
-
-<p>Let <code>maxLen</code> be the side length of the <strong>largest</strong> square you can obtain from any of the given rectangles.</p>
-
-<p>Return <em>the <strong>number</strong> of rectangles that can make a square with a side length of </em><code>maxLen</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rectangles = [[5,8],[3,9],[5,12],[16,5]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The largest squares you can get from each rectangle are of lengths [5,3,5,5].
-The largest possible square is of length 5, and you can get it out of 3 rectangles.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rectangles = [[2,3],[3,7],[4,3],[3,7]]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rectangles.length &lt;= 1000</code></li>
-	<li><code>rectangles[i].length == 2</code></li>
-	<li><code>1 &lt;= l<sub>i</sub>, w<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>l<sub>i</sub> != w<sub>i</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What is the length of the largest square the can be cut out of some rectangle? It'll be equal to min(rectangle.length, rectangle.width). Replace each rectangle with this value.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Calculate maxSize by iterating over the given rectangles and maximizing the answer with their values denoted in the first hint.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Then iterate again on the rectangles and calculate the number whose values = maxSize.
-</details>
diff --git a/problems/number-of-restricted-paths-from-first-to-last-node/README.md b/problems/number-of-restricted-paths-from-first-to-last-node/README.md
deleted file mode 100644
index 991d1a7a2..000000000
--- a/problems/number-of-restricted-paths-from-first-to-last-node/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-elements-to-add-to-form-a-given-sum "Minimum Elements to Add to Form a Given Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../make-the-xor-of-all-segments-equal-to-zero "Make the XOR of All Segments Equal to Zero")
-
-## [1786. Number of Restricted Paths From First to Last Node (Medium)](https://leetcode.com/problems/number-of-restricted-paths-from-first-to-last-node "从第一个节点出发到最后一个节点的受限路径数")
-
-<p>There is an undirected weighted connected graph. You are given a positive integer <code>n</code> which denotes that the graph has <code>n</code> nodes labeled from <code>1</code> to <code>n</code>, and an array <code>edges</code> where each <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>, weight<sub>i</sub>]</code> denotes that there is an edge between nodes <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code> with weight equal to <code>weight<sub>i</sub></code>.</p>
-
-<p>A path from node <code>start</code> to node <code>end</code> is a sequence of nodes <code>[z<sub>0</sub>, z<sub>1</sub>,<sub> </sub>z<sub>2</sub>, ..., z<sub>k</sub>]</code> such that <code>z<sub>0 </sub>= start</code> and <code>z<sub>k</sub> = end</code> and there is an edge between <code>z<sub>i</sub></code> and <code>z<sub>i+1</sub></code> where <code>0 &lt;= i &lt;= k-1</code>.</p>
-
-<p>The distance of a path is the sum of the weights on the edges of the path. Let <code>distanceToLastNode(x)</code> denote the shortest distance of a path between node <code>n</code> and node <code>x</code>. A <strong>restricted path</strong> is a path that also satisfies that <code>distanceToLastNode(z<sub>i</sub>) &gt; distanceToLastNode(z<sub>i+1</sub>)</code> where <code>0 &lt;= i &lt;= k-1</code>.</p>
-
-<p>Return <em>the number of restricted paths from node</em> <code>1</code> <em>to node</em> <code>n</code>. Since that number may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/17/restricted_paths_ex1.png" style="width: 351px; height: 341px;" />
-<pre>
-<strong>Input:</strong> n = 5, edges = [[1,2,3],[1,3,3],[2,3,1],[1,4,2],[5,2,2],[3,5,1],[5,4,10]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Each circle contains the node number in black and its <code>distanceToLastNode value in blue. </code>The three restricted paths are:
-1) 1 --&gt; 2 --&gt; 5
-2) 1 --&gt; 2 --&gt; 3 --&gt; 5
-3) 1 --&gt; 3 --&gt; 5
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/17/restricted_paths_ex22.png" style="width: 356px; height: 401px;" />
-<pre>
-<strong>Input:</strong> n = 7, edges = [[1,3,1],[4,1,2],[7,3,4],[2,5,3],[5,6,1],[6,7,2],[7,5,3],[2,6,4]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Each circle contains the node number in black and its <code>distanceToLastNode value in blue. </code>The only restricted path is 1 --&gt; 3 --&gt; 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>n - 1 &lt;= edges.length &lt;= 4 * 10<sup>4</sup></code></li>
-	<li><code>edges[i].length == 3</code></li>
-	<li><code>1 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n</code></li>
-	<li><code>u<sub>i </sub>!= v<sub>i</sub></code></li>
-	<li><code>1 &lt;= weight<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-	<li>There is at most one edge between any two nodes.</li>
-	<li>There is at least one path between any two nodes.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Run a Dijkstra from node numbered n to compute distance from the last node.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Consider all edges [u, v] one by one and direct them such that distance of u to n > distance of v to n. If both u and v are at the same distance from n, discard this edge.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Now this problem reduces to computing the number of paths from 1 to n in a DAG, a standard DP problem.
-</details>
diff --git a/problems/number-of-segments-in-a-string/README.md b/problems/number-of-segments-in-a-string/README.md
deleted file mode 100644
index ccd1d349a..000000000
--- a/problems/number-of-segments-in-a-string/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-genetic-mutation "Minimum Genetic Mutation")
-　　　　　　　　　　　　　　　　
-[Next >](../non-overlapping-intervals "Non-overlapping Intervals")
-
-## [434. Number of Segments in a String (Easy)](https://leetcode.com/problems/number-of-segments-in-a-string "字符串中的单词数")
-
-<p>Given a string <code>s</code>, return <em>the number of segments in the string</em>.</p>
-
-<p>A <strong>segment</strong> is defined to be a contiguous sequence of <strong>non-space characters</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;Hello, my name is John&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The five segments are [&quot;Hello,&quot;, &quot;my&quot;, &quot;name&quot;, &quot;is&quot;, &quot;John&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;Hello&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length &lt;= 300</code></li>
-	<li><code>s</code> consists of lowercase and uppercase English letters, digits, or one of the following characters <code>&quot;!@#$%^&amp;*()_+-=&#39;,.:&quot;</code>.</li>
-	<li>The only space character in <code>s</code> is <code>&#39; &#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/number-of-segments-in-a-string/number_of_segments_in_a_string.go b/problems/number-of-segments-in-a-string/number_of_segments_in_a_string.go
deleted file mode 100644
index 3e10139ce..000000000
--- a/problems/number-of-segments-in-a-string/number_of_segments_in_a_string.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem434
-
-import "strings"
-
-func countSegments(s string) int {
-	return len(strings.Fields(s))
-}
diff --git a/problems/number-of-segments-in-a-string/number_of_segments_in_a_string_test.go b/problems/number-of-segments-in-a-string/number_of_segments_in_a_string_test.go
deleted file mode 100644
index eeb8bdd01..000000000
--- a/problems/number-of-segments-in-a-string/number_of_segments_in_a_string_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem434
-
-import "testing"
-
-type testType struct {
-	in   string
-	want int
-}
-
-func TestCountSegments(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "Hello, my name is John",
-			want: 5,
-		},
-		{
-			in:   "",
-			want: 0,
-		},
-		{
-			in:   " ",
-			want: 0,
-		},
-		{
-			in:   " abc ",
-			want: 1,
-		},
-		{
-			in:   " abc  def  ",
-			want: 2,
-		},
-		{
-			in:   "love live! mu'sic forever",
-			want: 4,
-		},
-	}
-	for _, tt := range tests {
-		got := countSegments(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/number-of-sets-of-k-non-overlapping-line-segments/README.md b/problems/number-of-sets-of-k-non-overlapping-line-segments/README.md
deleted file mode 100644
index 72246a390..000000000
--- a/problems/number-of-sets-of-k-non-overlapping-line-segments/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../coordinate-with-maximum-network-quality "Coordinate With Maximum Network Quality")
-　　　　　　　　　　　　　　　　
-[Next >](../fancy-sequence "Fancy Sequence")
-
-## [1621. Number of Sets of K Non-Overlapping Line Segments (Medium)](https://leetcode.com/problems/number-of-sets-of-k-non-overlapping-line-segments "大小为 K 的不重叠线段的数目")
-
-<p>Given <code>n</code> points on a 1-D plane, where the <code>i<sup>th</sup></code> point (from <code>0</code> to <code>n-1</code>) is at <code>x = i</code>, find the number of ways we can draw <strong>exactly</strong> <code>k</code> <strong>non-overlapping</strong> line segments such that each segment covers two or more points. The endpoints of each segment must have <strong>integral coordinates</strong>. The <code>k</code> line segments <strong>do not</strong> have to cover all <code>n</code> points, and they are <strong>allowed</strong> to share endpoints.</p>
-
-<p>Return <em>the number of ways we can draw </em><code>k</code><em> non-overlapping line segments</em><em>.</em> Since this number can be huge, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/07/ex1.png" style="width: 179px; height: 222px;" />
-<pre>
-<strong>Input:</strong> n = 4, k = 2
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The two line segments are shown in red and blue.
-The image above shows the 5 different ways {(0,2),(2,3)}, {(0,1),(1,3)}, {(0,1),(2,3)}, {(1,2),(2,3)}, {(0,1),(1,2)}.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 1
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The 3 ways are {(0,1)}, {(0,2)}, {(1,2)}.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 30, k = 7
-<strong>Output:</strong> 796297179
-<strong>Explanation:</strong> The total number of possible ways to draw 7 line segments is 3796297200. Taking this number modulo 10<sup>9</sup> + 7 gives us 796297179.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= k &lt;= n-1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to use dynamic programming where the current index and remaining number of line segments to form can describe any intermediate state.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To make the computation of each state in constant time, we could add another flag to the state that indicates whether or not we are in the middle of placing a line (placed start point but no endpoint).
-</details>
diff --git a/problems/number-of-ships-in-a-rectangle/README.md b/problems/number-of-ships-in-a-rectangle/README.md
deleted file mode 100644
index 754422647..000000000
--- a/problems/number-of-ships-in-a-rectangle/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-tree-nodes "Delete Tree Nodes")
-　　　　　　　　　　　　　　　　
-[Next >](../find-winner-on-a-tic-tac-toe-game "Find Winner on a Tic Tac Toe Game")
-
-## [1274. Number of Ships in a Rectangle (Hard)](https://leetcode.com/problems/number-of-ships-in-a-rectangle "矩形内船只的数目")
-
-<p><em>(This problem is an&nbsp;<strong>interactive problem</strong>.)</em></p>
-
-<p>On the sea represented by a cartesian plane, each ship is located at an integer point, and each integer point may contain at most 1 ship.</p>
-
-<p>You have a function <code>Sea.hasShips(topRight, bottomLeft)</code> which takes two points&nbsp;as arguments and returns <code>true</code>&nbsp;if and only if there is at least one ship in the rectangle represented by the two points, including on the boundary.</p>
-
-<p>Given two points, which are the top right and bottom left corners of a rectangle, return the number of ships present in that rectangle.&nbsp;&nbsp;It is guaranteed that there are <strong>at most 10 ships</strong> in that rectangle.</p>
-
-<p>Submissions making <strong>more than 400 calls</strong> to&nbsp;<code>hasShips</code>&nbsp;will be judged <em>Wrong Answer</em>.&nbsp; Also, any solutions that attempt to circumvent the judge&nbsp;will result in disqualification.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example :</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/07/26/1445_example_1.PNG" style="width: 400px; height: 404px;" /></p>
-
-<pre>
-<strong>Input:</strong> 
-ships = [[1,1],[2,2],[3,3],[5,5]], topRight = [4,4], bottomLeft = [0,0]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> From [0,0] to [4,4] we can count 3 ships within the range.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>On the input <code>ships</code> is only given to initialize the map internally.&nbsp;You must solve this problem &quot;blindfolded&quot;. In other words, you must find the answer using the given <code>hasShips</code> API, without knowing the <code>ships</code>&nbsp;position.</li>
-	<li><code>0 &lt;=&nbsp;bottomLeft[0]&nbsp;&lt;= topRight[0]&nbsp;&lt;= 1000</code></li>
-	<li><code>0 &lt;=&nbsp;bottomLeft[1]&nbsp;&lt;= topRight[1]&nbsp;&lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use divide and conquer technique.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Divide the query rectangle into 4 rectangles.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use recursion to continue with the rectangles that has ships only.
-</details>
diff --git a/problems/number-of-smooth-descent-periods-of-a-stock/README.md b/problems/number-of-smooth-descent-periods-of-a-stock/README.md
deleted file mode 100644
index 8a05be526..000000000
--- a/problems/number-of-smooth-descent-periods-of-a-stock/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../adding-spaces-to-a-string "Adding Spaces to a String")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-operations-to-make-the-array-k-increasing "Minimum Operations to Make the Array K-Increasing")
-
-## [2110. Number of Smooth Descent Periods of a Stock (Medium)](https://leetcode.com/problems/number-of-smooth-descent-periods-of-a-stock "股票平滑下跌阶段的数目")
-
-<p>You are given an integer array <code>prices</code> representing the daily price history of a stock, where <code>prices[i]</code> is the stock price on the <code>i<sup>th</sup></code> day.</p>
-
-<p>A <strong>smooth descent period</strong> of a stock consists of <strong>one or more contiguous</strong> days such that the price on each day is <strong>lower</strong> than the price on the <strong>preceding day</strong> by <strong>exactly</strong> <code>1</code>. The first day of the period is exempted from this rule.</p>
-
-<p>Return <em>the number of <strong>smooth descent periods</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [3,2,1,4]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> There are 7 smooth descent periods:
-[3], [2], [1], [4], [3,2], [2,1], and [3,2,1]
-Note that a period with one day is a smooth descent period by the definition.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [8,6,7,7]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are 4 smooth descent periods: [8], [6], [7], and [7]
-Note that [8,6] is not a smooth descent period as 8 - 6 &ne; 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> prices = [1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There is 1 smooth descent period: [1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= prices.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= prices[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Any array is a series of adjacent longest possible smooth descent periods. For example, [5,3,2,1,7,6] is [5] + [3,2,1] + [7,6].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think of a 2-pointer approach to traverse the array and find each longest possible period.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Suppose you found the longest possible period with a length of k. How many periods are within that period? How can you count them quickly? Think of the formula to calculate the sum of 1, 2, 3, ..., k.
-</details>
diff --git a/problems/number-of-spaces-cleaning-robot-cleaned/README.md b/problems/number-of-spaces-cleaning-robot-cleaned/README.md
deleted file mode 100644
index c40efb276..000000000
--- a/problems/number-of-spaces-cleaning-robot-cleaned/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-an-original-string-exists-given-two-encoded-strings "Check if an Original String Exists Given Two Encoded Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../count-vowel-substrings-of-a-string "Count Vowel Substrings of a String")
-
-## [2061. Number of Spaces Cleaning Robot Cleaned (Medium)](https://leetcode.com/problems/number-of-spaces-cleaning-robot-cleaned "扫地机器人清扫过的空间个数")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate how the robot moves and keep track of how many spaces it has cleaned so far.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When can we stop the simulation?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-When the robot reaches a space that it has already cleaned and is facing the same direction as before, we can stop the simulation.
-</details>
diff --git a/problems/number-of-squareful-arrays/README.md b/problems/number-of-squareful-arrays/README.md
deleted file mode 100644
index bfd6778ee..000000000
--- a/problems/number-of-squareful-arrays/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-k-consecutive-bit-flips "Minimum Number of K Consecutive Bit Flips")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-town-judge "Find the Town Judge")
-
-## [996. Number of Squareful Arrays (Hard)](https://leetcode.com/problems/number-of-squareful-arrays "正方形数组的数目")
-
-<p>An array is <strong>squareful</strong> if the sum of every pair of adjacent elements is a <strong>perfect square</strong>.</p>
-
-<p>Given an integer array nums, return <em>the number of permutations of </em><code>nums</code><em> that are <strong>squareful</strong></em>.</p>
-
-<p>Two permutations <code>perm1</code> and <code>perm2</code> are different if there is some index <code>i</code> such that <code>perm1[i] != perm2[i]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,17,8]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> [1,8,17] and [17,8,1] are the valid permutations.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,2]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 12</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Similar Questions
-  1. [Permutations II](../permutations-ii) (Medium)
diff --git a/problems/number-of-squareful-arrays/number_of_squareful_arrays.go b/problems/number-of-squareful-arrays/number_of_squareful_arrays.go
deleted file mode 100644
index 687ab0359..000000000
--- a/problems/number-of-squareful-arrays/number_of_squareful_arrays.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem996
diff --git a/problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one/README.md b/problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one/README.md
deleted file mode 100644
index a94b24aca..000000000
--- a/problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-subsequence-in-non-increasing-order "Minimum Subsequence in Non-Increasing Order")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-happy-string "Longest Happy String")
-
-## [1404. Number of Steps to Reduce a Number in Binary Representation to One (Medium)](https://leetcode.com/problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one "将二进制表示减到 1 的步骤数")
-
-<p>Given the binary representation of an integer as a string <code>s</code>, return <em>the number of steps to reduce it to </em><code>1</code><em> under the following rules</em>:</p>
-
-<ul>
-	<li>
-	<p>If the current number is even, you have to divide it by <code>2</code>.</p>
-	</li>
-	<li>
-	<p>If the current number is odd, you have to add <code>1</code> to it.</p>
-	</li>
-</ul>
-
-<p>It is guaranteed that you can always reach one for all test cases.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1101&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> &quot;1101&quot; corressponds to number 13 in their decimal representation.
-Step 1) 13 is odd, add 1 and obtain 14.&nbsp;
-Step 2) 14 is even, divide by 2 and obtain 7.
-Step 3) 7 is odd, add 1 and obtain 8.
-Step 4) 8 is even, divide by 2 and obtain 4.&nbsp; 
-Step 5) 4 is even, divide by 2 and obtain 2.&nbsp;
-Step 6) 2 is even, divide by 2 and obtain 1.&nbsp; 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;10&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> &quot;10&quot; corressponds to number 2 in their decimal representation.
-Step 1) 2 is even, divide by 2 and obtain 1.&nbsp; 
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1&quot;
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length&nbsp;&lt;= 500</code></li>
-	<li><code>s</code> consists of characters &#39;0&#39; or &#39;1&#39;</li>
-	<li><code>s[0] == &#39;1&#39;</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Minimum Moves to Reach Target Score](../minimum-moves-to-reach-target-score) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Read the string from right to left, if the string ends in '0' then the number is even otherwise it is odd.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Simulate the steps described in the binary string.
-</details>
diff --git a/problems/number-of-steps-to-reduce-a-number-to-zero/README.md b/problems/number-of-steps-to-reduce-a-number-to-zero/README.md
deleted file mode 100644
index 6a5b12197..000000000
--- a/problems/number-of-steps-to-reduce-a-number-to-zero/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../movie-rating "Movie Rating")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold "Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold")
-
-## [1342. Number of Steps to Reduce a Number to Zero (Easy)](https://leetcode.com/problems/number-of-steps-to-reduce-a-number-to-zero "将数字变成 0 的操作次数")
-
-<p>Given an integer <code>num</code>, return <em>the number of steps to reduce it to zero</em>.</p>
-
-<p>In one step, if the current number is even, you have to divide it by <code>2</code>, otherwise, you have to subtract <code>1</code> from it.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 14
-<strong>Output:</strong> 6
-<strong>Explanation:</strong>&nbsp;
-Step 1) 14 is even; divide by 2 and obtain 7.&nbsp;
-Step 2) 7 is odd; subtract 1 and obtain 6.
-Step 3) 6 is even; divide by 2 and obtain 3.&nbsp;
-Step 4) 3 is odd; subtract 1 and obtain 2.&nbsp;
-Step 5) 2 is even; divide by 2 and obtain 1.&nbsp;
-Step 6) 1 is odd; subtract 1 and obtain 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 8
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>&nbsp;
-Step 1) 8 is even; divide by 2 and obtain 4.&nbsp;
-Step 2) 4 is even; divide by 2 and obtain 2.&nbsp;
-Step 3) 2 is even; divide by 2 and obtain 1.&nbsp;
-Step 4) 1 is odd; subtract 1 and obtain 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 123
-<strong>Output:</strong> 12
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= num &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Minimum Moves to Reach Target Score](../minimum-moves-to-reach-target-score) (Medium)
-  1. [Count Operations to Obtain Zero](../count-operations-to-obtain-zero) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process to get the final answer.
-</details>
diff --git a/problems/number-of-strings-that-appear-as-substrings-in-word/README.md b/problems/number-of-strings-that-appear-as-substrings-in-word/README.md
deleted file mode 100644
index f5aec31f7..000000000
--- a/problems/number-of-strings-that-appear-as-substrings-in-word/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-searchable-numbers-in-an-unsorted-array "Binary Searchable Numbers in an Unsorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../array-with-elements-not-equal-to-average-of-neighbors "Array With Elements Not Equal to Average of Neighbors")
-
-## [1967. Number of Strings That Appear as Substrings in Word (Easy)](https://leetcode.com/problems/number-of-strings-that-appear-as-substrings-in-word "作为子字符串出现在单词中的字符串数目")
-
-<p>Given an array of strings <code>patterns</code> and a string <code>word</code>, return <em>the <strong>number</strong> of strings in </em><code>patterns</code><em> that exist as a <strong>substring</strong> in </em><code>word</code>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> patterns = [&quot;a&quot;,&quot;abc&quot;,&quot;bc&quot;,&quot;d&quot;], word = &quot;abc&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-- &quot;a&quot; appears as a substring in &quot;<u>a</u>bc&quot;.
-- &quot;abc&quot; appears as a substring in &quot;<u>abc</u>&quot;.
-- &quot;bc&quot; appears as a substring in &quot;a<u>bc</u>&quot;.
-- &quot;d&quot; does not appear as a substring in &quot;abc&quot;.
-3 of the strings in patterns appear as a substring in word.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> patterns = [&quot;a&quot;,&quot;b&quot;,&quot;c&quot;], word = &quot;aaaaabbbbb&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-- &quot;a&quot; appears as a substring in &quot;a<u>a</u>aaabbbbb&quot;.
-- &quot;b&quot; appears as a substring in &quot;aaaaabbbb<u>b</u>&quot;.
-- &quot;c&quot; does not appear as a substring in &quot;aaaaabbbbb&quot;.
-2 of the strings in patterns appear as a substring in word.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> patterns = [&quot;a&quot;,&quot;a&quot;,&quot;a&quot;], word = &quot;ab&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Each of the patterns appears as a substring in word &quot;<u>a</u>b&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= patterns.length &lt;= 100</code></li>
-	<li><code>1 &lt;= patterns[i].length &lt;= 100</code></li>
-	<li><code>1 &lt;= word.length &lt;= 100</code></li>
-	<li><code>patterns[i]</code> and <code>word</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Deal with each of the patterns individually.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the built-in function in the language you are using to find if the pattern exists as a substring in <code>word</code>.
-</details>
diff --git a/problems/number-of-students-doing-homework-at-a-given-time/README.md b/problems/number-of-students-doing-homework-at-a-given-time/README.md
deleted file mode 100644
index 0378b7668..000000000
--- a/problems/number-of-students-doing-homework-at-a-given-time/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../form-largest-integer-with-digits-that-add-up-to-target "Form Largest Integer With Digits That Add up to Target")
-　　　　　　　　　　　　　　　　
-[Next >](../rearrange-words-in-a-sentence "Rearrange Words in a Sentence")
-
-## [1450. Number of Students Doing Homework at a Given Time (Easy)](https://leetcode.com/problems/number-of-students-doing-homework-at-a-given-time "在既定时间做作业的学生人数")
-
-<p>Given two integer arrays <code>startTime</code> and <code>endTime</code> and given an integer <code>queryTime</code>.</p>
-
-<p>The <code>ith</code> student started doing their homework at the time <code>startTime[i]</code> and finished it at time <code>endTime[i]</code>.</p>
-
-<p>Return <em>the number of students</em> doing their homework at time <code>queryTime</code>. More formally, return the number of students where <code>queryTime</code> lays in the interval <code>[startTime[i], endTime[i]]</code> inclusive.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> startTime = [1,2,3], endTime = [3,2,7], queryTime = 4
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> We have 3 students where:
-The first student started doing homework at time 1 and finished at time 3 and wasn&#39;t doing anything at time 4.
-The second student started doing homework at time 2 and finished at time 2 and also wasn&#39;t doing anything at time 4.
-The third student started doing homework at time 3 and finished at time 7 and was the only student doing homework at time 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> startTime = [4], endTime = [4], queryTime = 4
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only student was doing their homework at the queryTime.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>startTime.length == endTime.length</code></li>
-	<li><code>1 &lt;= startTime.length &lt;= 100</code></li>
-	<li><code>1 &lt;= startTime[i] &lt;= endTime[i] &lt;= 1000</code></li>
-	<li><code>1 &lt;= queryTime &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Imagine that startTime[i] and endTime[i] form an interval (i.e. [startTime[i], endTime[i]]).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The answer is how many times the queryTime laid in those mentioned intervals.
-</details>
diff --git a/problems/number-of-students-unable-to-eat-lunch/README.md b/problems/number-of-students-unable-to-eat-lunch/README.md
deleted file mode 100644
index 010fc4510..000000000
--- a/problems/number-of-students-unable-to-eat-lunch/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-calls-between-two-persons "Number of Calls Between Two Persons")
-　　　　　　　　　　　　　　　　
-[Next >](../average-waiting-time "Average Waiting Time")
-
-## [1700. Number of Students Unable to Eat Lunch (Easy)](https://leetcode.com/problems/number-of-students-unable-to-eat-lunch "无法吃午餐的学生数量")
-
-<p>The school cafeteria offers circular and square sandwiches at lunch break, referred to by numbers <code>0</code> and <code>1</code> respectively. All students stand in a queue. Each student either prefers square or circular sandwiches.</p>
-
-<p>The number of sandwiches in the cafeteria is equal to the number of students. The sandwiches are placed in a <strong>stack</strong>. At each step:</p>
-
-<ul>
-	<li>If the student at the front of the queue <strong>prefers</strong> the sandwich on the top of the stack, they will <strong>take it</strong> and leave the queue.</li>
-	<li>Otherwise, they will <strong>leave it</strong> and go to the queue&#39;s end.</li>
-</ul>
-
-<p>This continues until none of the queue students want to take the top sandwich and are thus unable to eat.</p>
-
-<p>You are given two integer arrays <code>students</code> and <code>sandwiches</code> where <code>sandwiches[i]</code> is the type of the <code>i<sup>​​​​​​th</sup></code> sandwich in the stack (<code>i = 0</code> is the top of the stack) and <code>students[j]</code> is the preference of the <code>j<sup>​​​​​​th</sup></code> student in the initial queue (<code>j = 0</code> is the front of the queue). Return <em>the number of students that are unable to eat.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> students = [1,1,0,0], sandwiches = [0,1,0,1]
-<strong>Output:</strong> 0<strong> 
-Explanation:</strong>
-- Front student leaves the top sandwich and returns to the end of the line making students = [1,0,0,1].
-- Front student leaves the top sandwich and returns to the end of the line making students = [0,0,1,1].
-- Front student takes the top sandwich and leaves the line making students = [0,1,1] and sandwiches = [1,0,1].
-- Front student leaves the top sandwich and returns to the end of the line making students = [1,1,0].
-- Front student takes the top sandwich and leaves the line making students = [1,0] and sandwiches = [0,1].
-- Front student leaves the top sandwich and returns to the end of the line making students = [0,1].
-- Front student takes the top sandwich and leaves the line making students = [1] and sandwiches = [1].
-- Front student takes the top sandwich and leaves the line making students = [] and sandwiches = [].
-Hence all students are able to eat.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> students = [1,1,1,0,0,1], sandwiches = [1,0,0,0,1,1]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= students.length, sandwiches.length &lt;= 100</code></li>
-	<li><code>students.length == sandwiches.length</code></li>
-	<li><code>sandwiches[i]</code> is <code>0</code> or <code>1</code>.</li>
-	<li><code>students[i]</code> is <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Time Needed to Buy Tickets](../time-needed-to-buy-tickets) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the given in the statement
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Calculate those who will eat instead of those who will not.
-</details>
diff --git a/problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold/README.md b/problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold/README.md
deleted file mode 100644
index ea0d4c7dd..000000000
--- a/problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-steps-to-reduce-a-number-to-zero "Number of Steps to Reduce a Number to Zero")
-　　　　　　　　　　　　　　　　
-[Next >](../angle-between-hands-of-a-clock "Angle Between Hands of a Clock")
-
-## [1343. Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold (Medium)](https://leetcode.com/problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold "大小为 K 且平均值大于等于阈值的子数组数目")
-
-<p>Given an array of integers <code>arr</code> and two integers <code>k</code> and <code>threshold</code>, return <em>the number of sub-arrays of size </em><code>k</code><em> and average greater than or equal to </em><code>threshold</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,2,2,2,5,5,5,8], k = 3, threshold = 4
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Sub-arrays [2,5,5],[5,5,5] and [5,5,8] have averages 4, 5 and 6 respectively. All other sub-arrays of size 3 have averages less than 4 (the threshold).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [11,13,17,23,29,31,7,5,2,3], k = 3, threshold = 5
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The first 6 sub-arrays of size 3 have averages greater than 5. Note that averages are not integers.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= k &lt;= arr.length</code></li>
-	<li><code>0 &lt;= threshold &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Start with a window of size K and test its average against the threshold.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep moving the window by one element maintaining its size k until you cover the whole array. count number of windows that satisfy that its average is greater than the threshold.
-</details>
diff --git a/problems/number-of-sub-arrays-with-odd-sum/README.md b/problems/number-of-sub-arrays-with-odd-sum/README.md
deleted file mode 100644
index 98a5c903c..000000000
--- a/problems/number-of-sub-arrays-with-odd-sum/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-odd-numbers-in-an-interval-range "Count Odd Numbers in an Interval Range")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-good-ways-to-split-a-string "Number of Good Ways to Split a String")
-
-## [1524. Number of Sub-arrays With Odd Sum (Medium)](https://leetcode.com/problems/number-of-sub-arrays-with-odd-sum "和为奇数的子数组数目")
-
-<p>Given an array of integers <code>arr</code>, return <em>the number of subarrays with an <strong>odd</strong> sum</em>.</p>
-
-<p>Since the answer can be very large, return it modulo <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,3,5]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> All subarrays are [[1],[1,3],[1,3,5],[3],[3,5],[5]]
-All sub-arrays sum are [1,4,9,3,8,5].
-Odd sums are [1,9,3,5] so the answer is 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,4,6]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> All subarrays are [[2],[2,4],[2,4,6],[4],[4,6],[6]]
-All sub-arrays sum are [2,6,12,4,10,6].
-All sub-arrays have even sum and the answer is 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4,5,6,7]
-<strong>Output:</strong> 16
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Subsequence of Size K With the Largest Even Sum](../subsequence-of-size-k-with-the-largest-even-sum) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can we use the accumulative sum to keep track of all the odd-sum sub-arrays ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-if the current accu sum is odd, we care only about previous even accu sums and vice versa.
-</details>
diff --git a/problems/number-of-subarrays-with-bounded-maximum/README.md b/problems/number-of-subarrays-with-bounded-maximum/README.md
deleted file mode 100644
index 80823a666..000000000
--- a/problems/number-of-subarrays-with-bounded-maximum/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-tic-tac-toe-state "Valid Tic-Tac-Toe State")
-　　　　　　　　　　　　　　　　
-[Next >](../rotate-string "Rotate String")
-
-## [795. Number of Subarrays with Bounded Maximum (Medium)](https://leetcode.com/problems/number-of-subarrays-with-bounded-maximum "区间子数组个数")
-
-<p>Given an integer array <code>nums</code> and two integers <code>left</code> and <code>right</code>, return <em>the number of contiguous non-empty <strong>subarrays</strong> such that the value of the maximum array element in that subarray is in the range </em><code>[left, right]</code>.</p>
-
-<p>The test cases are generated so that the answer will fit in a <strong>32-bit</strong> integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,4,3], left = 2, right = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> There are three subarrays that meet the requirements: [2], [2, 1], [3].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,9,2,5,6], left = 2, right = 8
-<strong>Output:</strong> 7
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= left &lt;= right &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
diff --git a/problems/number-of-subarrays-with-bounded-maximum/number_of_subarrays_with_bounded_maximum.go b/problems/number-of-subarrays-with-bounded-maximum/number_of_subarrays_with_bounded_maximum.go
deleted file mode 100644
index 6ac73f4d9..000000000
--- a/problems/number-of-subarrays-with-bounded-maximum/number_of_subarrays_with_bounded_maximum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem795
diff --git a/problems/number-of-subarrays-with-bounded-maximum/number_of_subarrays_with_bounded_maximum_test.go b/problems/number-of-subarrays-with-bounded-maximum/number_of_subarrays_with_bounded_maximum_test.go
deleted file mode 100644
index 6ac73f4d9..000000000
--- a/problems/number-of-subarrays-with-bounded-maximum/number_of_subarrays_with_bounded_maximum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem795
diff --git a/problems/number-of-submatrices-that-sum-to-target/README.md b/problems/number-of-submatrices-that-sum-to-target/README.md
deleted file mode 100644
index b9b2aebe9..000000000
--- a/problems/number-of-submatrices-that-sum-to-target/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../adding-two-negabinary-numbers "Adding Two Negabinary Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../project-employees-i "Project Employees I")
-
-## [1074. Number of Submatrices That Sum to Target (Hard)](https://leetcode.com/problems/number-of-submatrices-that-sum-to-target "元素和为目标值的子矩阵数量")
-
-<p>Given a <code>matrix</code>&nbsp;and a <code>target</code>, return the number of non-empty submatrices that sum to <font face="monospace">target</font>.</p>
-
-<p>A submatrix <code>x1, y1, x2, y2</code> is the set of all cells <code>matrix[x][y]</code> with <code>x1 &lt;= x &lt;= x2</code> and <code>y1 &lt;= y &lt;= y2</code>.</p>
-
-<p>Two submatrices <code>(x1, y1, x2, y2)</code> and <code>(x1&#39;, y1&#39;, x2&#39;, y2&#39;)</code> are different if they have some coordinate&nbsp;that is different: for example, if <code>x1 != x1&#39;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/02/mate1.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> matrix = [[0,1,0],[1,1,1],[0,1,0]], target = 0
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The four 1x1 submatrices that only contain 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[1,-1],[-1,1]], target = 0
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The two 1x2 submatrices, plus the two 2x1 submatrices, plus the 2x2 submatrix.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[904]], target = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= matrix.length &lt;= 100</code></li>
-	<li><code>1 &lt;= matrix[0].length &lt;= 100</code></li>
-	<li><code>-1000 &lt;= matrix[i] &lt;= 1000</code></li>
-	<li><code>-10^8 &lt;= target &lt;= 10^8</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Using a 2D prefix sum, we can query the sum of any submatrix in O(1) time.
-Now for each (r1, r2), we can find the largest sum of a submatrix that uses every row in [r1, r2] in linear time using a sliding window.
-</details>
diff --git a/problems/number-of-submatrices-that-sum-to-target/number_of_submatrices_that_sum_to_target.go b/problems/number-of-submatrices-that-sum-to-target/number_of_submatrices_that_sum_to_target.go
deleted file mode 100644
index 052ca2755..000000000
--- a/problems/number-of-submatrices-that-sum-to-target/number_of_submatrices_that_sum_to_target.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package problem1074
-
-func numSubmatrixSumTarget(M [][]int, target int) int {
-	m, n := len(M), len(M[0])
-
-	S := [301][301]int{}
-	for i := 1; i <= m; i++ {
-		for j := 1; j <= n; j++ {
-			S[i][j] = S[i][j-1] + M[i-1][j-1]
-		}
-	}
-
-	res := 0
-
-	for y1 := 0; y1 < n; y1++ {
-		for y2 := y1 + 1; y2 <= n; y2++ {
-			count := make(map[int]int, m)
-			sum := 0
-			for x := 0; x <= m; x++ {
-				sum += S[x][y2] - S[x][y1]
-				res += count[sum-target]
-				count[sum]++
-			}
-		}
-	}
-
-	return res
-}
diff --git a/problems/number-of-subsequences-that-satisfy-the-given-sum-condition/README.md b/problems/number-of-subsequences-that-satisfy-the-given-sum-condition/README.md
deleted file mode 100644
index e05fcbde2..000000000
--- a/problems/number-of-subsequences-that-satisfy-the-given-sum-condition/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-array-pairs-are-divisible-by-k "Check If Array Pairs Are Divisible by k")
-　　　　　　　　　　　　　　　　
-[Next >](../max-value-of-equation "Max Value of Equation")
-
-## [1498. Number of Subsequences That Satisfy the Given Sum Condition (Medium)](https://leetcode.com/problems/number-of-subsequences-that-satisfy-the-given-sum-condition "满足条件的子序列数目")
-
-<p>You are given an array of integers <code>nums</code> and an integer <code>target</code>.</p>
-
-<p>Return <em>the number of <strong>non-empty</strong> subsequences of </em><code>nums</code><em> such that the sum of the minimum and maximum element on it is less or equal to </em><code>target</code>. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,5,6,7], target = 9
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are 4 subsequences that satisfy the condition.
-[3] -&gt; Min value + max value &lt;= target (3 + 3 &lt;= 9)
-[3,5] -&gt; (3 + 5 &lt;= 9)
-[3,5,6] -&gt; (3 + 6 &lt;= 9)
-[3,6] -&gt; (3 + 6 &lt;= 9)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,3,6,8], target = 10
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> There are 6 subsequences that satisfy the condition. (nums can have repeated numbers).
-[3] , [3] , [3,3], [3,6] , [3,6] , [3,3,6]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,3,4,6,7], target = 12
-<strong>Output:</strong> 61
-<strong>Explanation:</strong> There are 63 non-empty subsequences, two of them do not satisfy the condition ([6,7], [7]).
-Number of valid subsequences (63 - 2 = 61).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= target &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the array nums.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use two pointers approach: Given an index i (choose it as the minimum in a subsequence) find the maximum j where j ≥ i and nums[i] +nums[j] ≤ target.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Count the number of subsequences.
-</details>
diff --git a/problems/number-of-substrings-containing-all-three-characters/README.md b/problems/number-of-substrings-containing-all-three-characters/README.md
deleted file mode 100644
index 06af64589..000000000
--- a/problems/number-of-substrings-containing-all-three-characters/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../apply-discount-every-n-orders "Apply Discount Every n Orders")
-　　　　　　　　　　　　　　　　
-[Next >](../count-all-valid-pickup-and-delivery-options "Count All Valid Pickup and Delivery Options")
-
-## [1358. Number of Substrings Containing All Three Characters (Medium)](https://leetcode.com/problems/number-of-substrings-containing-all-three-characters "包含所有三种字符的子字符串数目")
-
-<p>Given a string <code>s</code>&nbsp;consisting only of characters <em>a</em>, <em>b</em> and <em>c</em>.</p>
-
-<p>Return the number of substrings containing <b>at least</b>&nbsp;one occurrence of all these characters <em>a</em>, <em>b</em> and <em>c</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcabc&quot;
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> The substrings containing&nbsp;at least&nbsp;one occurrence of the characters&nbsp;<em>a</em>,&nbsp;<em>b</em>&nbsp;and&nbsp;<em>c are &quot;</em>abc<em>&quot;, &quot;</em>abca<em>&quot;, &quot;</em>abcab<em>&quot;, &quot;</em>abcabc<em>&quot;, &quot;</em>bca<em>&quot;, &quot;</em>bcab<em>&quot;, &quot;</em>bcabc<em>&quot;, &quot;</em>cab<em>&quot;, &quot;</em>cabc<em>&quot; </em>and<em> &quot;</em>abc<em>&quot; </em>(<strong>again</strong>)<em>. </em>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaacb&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The substrings containing&nbsp;at least&nbsp;one occurrence of the characters&nbsp;<em>a</em>,&nbsp;<em>b</em>&nbsp;and&nbsp;<em>c are &quot;</em>aaacb<em>&quot;, &quot;</em>aacb<em>&quot; </em>and<em> &quot;</em>acb<em>&quot;.</em><em> </em>
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= s.length &lt;= 5 x 10^4</code></li>
-	<li><code>s</code>&nbsp;only consists of&nbsp;<em>a</em>, <em>b</em> or <em>c&nbsp;</em>characters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each position we simply need to find the first occurrence of a/b/c on or after this position.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-So we can pre-compute three link-list of indices of each a, b, and c.
-</details>
diff --git a/problems/number-of-substrings-with-only-1s/README.md b/problems/number-of-substrings-with-only-1s/README.md
deleted file mode 100644
index 3e0062cdb..000000000
--- a/problems/number-of-substrings-with-only-1s/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-good-pairs "Number of Good Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../path-with-maximum-probability "Path with Maximum Probability")
-
-## [1513. Number of Substrings With Only 1s (Medium)](https://leetcode.com/problems/number-of-substrings-with-only-1s "仅含 1 的子串数")
-
-<p>Given a binary string <code>s</code>, return <em>the number of substrings with all characters</em> <code>1</code><em>&#39;s</em>. Since the answer may be too large, return it modulo <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0110111&quot;
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> There are 9 substring in total with only 1&#39;s characters.
-&quot;1&quot; -&gt; 5 times.
-&quot;11&quot; -&gt; 3 times.
-&quot;111&quot; -&gt; 1 time.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;101&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Substring &quot;1&quot; is shown 2 times in s.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;111111&quot;
-<strong>Output:</strong> 21
-<strong>Explanation:</strong> Each substring contains only 1&#39;s characters.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Count Number of Homogenous Substrings](../count-number-of-homogenous-substrings) (Medium)
-  1. [Count Vowel Substrings of a String](../count-vowel-substrings-of-a-string) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count number of 1s in each consecutive-1 group. For a group with n consecutive 1s, the total contribution of it to the final answer is (n + 1) * n // 2.
-</details>
diff --git a/problems/number-of-transactions-per-visit/README.md b/problems/number-of-transactions-per-visit/README.md
deleted file mode 100644
index e08f68f39..000000000
--- a/problems/number-of-transactions-per-visit/README.md
+++ /dev/null
@@ -1,97 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-difficulty-of-a-job-schedule "Minimum Difficulty of a Job Schedule")
-　　　　　　　　　　　　　　　　
-[Next >](../the-k-weakest-rows-in-a-matrix "The K Weakest Rows in a Matrix")
-
-## [1336. Number of Transactions per Visit (Hard)](https://leetcode.com/problems/number-of-transactions-per-visit "每次访问的交易次数")
-
-<p>Table: <code>Visits</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| user_id       | int     |
-| visit_date    | date    |
-+---------------+---------+
-(user_id, visit_date) is the primary key for this table.
-Each row of this table indicates that user_id has visited the bank in visit_date.
-</pre>
-
-<p>Table: <code>Transactions</code></p>
-<pre>
-+------------------+---------+
-| Column Name      | Type    |
-+------------------+---------+
-| user_id          | int     |
-| transaction_date | date    |
-| amount           | int     |
-+------------------+---------+
-There is no primary key for this table, it may contain duplicates.
-Each row of this table indicates that user_id has done a transaction of amount in transaction_date.
-It is guaranteed that the user has visited the bank in the transaction_date.(i.e The Visits table contains (user_id, transaction_date) in one row)
-</pre>
- 
-Write an SQL query to find how many users visited the bank and didn't do any transactions, how many visited the bank and did one transaction and so on.
-
-The result table will contain two columns transactions_count which is the number of transactions done in one visit and visits_count which is the corresponding number of users who did transactions_count in one visit to the bank. transactions_count should take all values from 0 to max(transactions_count) done by one or more users.
-
-Order the result table by transactions_count.
-
-The query result format is in the following example:
-
-<pre>
-Visits table:
-+---------+------------+
-| user_id | visit_date |
-+---------+------------+
-| 1       | 2020-01-01 |
-| 2       | 2020-01-02 |
-| 12      | 2020-01-01 |
-| 19      | 2020-01-03 |
-| 1       | 2020-01-02 |
-| 2       | 2020-01-03 |
-| 1       | 2020-01-04 |
-| 7       | 2020-01-11 |
-| 9       | 2020-01-25 |
-| 8       | 2020-01-28 |
-+---------+------------+
-Transactions table:
-+---------+------------------+--------+
-| user_id | transaction_date | amount |
-+---------+------------------+--------+
-| 1       | 2020-01-02       | 120    |
-| 2       | 2020-01-03       | 22     |
-| 7       | 2020-01-11       | 232    |
-| 1       | 2020-01-04       | 7      |
-| 9       | 2020-01-25       | 33     |
-| 9       | 2020-01-25       | 66     |
-| 8       | 2020-01-28       | 1      |
-| 9       | 2020-01-25       | 99     |
-+---------+------------------+--------+
-Result table:
-+--------------------+--------------+
-| transactions_count | visits_count |
-+--------------------+--------------+
-| 0                  | 4            |
-| 1                  | 5            |
-| 2                  | 0            |
-| 3                  | 1            |
-+--------------------+--------------+
-Users 1, 2, 12 and 19 visited the bank in 2020-01-01, 2020-01-02, 2020-01-01 and 2020-01-03 respectively, and didn't do any transactions.
-So we have visits_count = 4 for transactions_count = 0.
-Users 2, 7 and 8 visited the bank in 2020-01-03, 2020-01-11 and 2020-01-28 respectively, and did one transaction.
-User 1 Also visited the bank in 2020-01-02 and 2020-01-04 and did one transaction each day.
-So we have total visits_count = 5 for transactions_count = 1.
-For transactions_count = 2 we don't have any users who visited the bank and did two transactions.
-For transactions_count = 3 we have user 9 who visited the bank in 2020-01-25 and did three transactions.
-Note that we stopped at transactions_count = 3 as this is the maximum number of transactions done by one user in one visit to the bank.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/number-of-transactions-per-visit/mysql_schemas.sql b/problems/number-of-transactions-per-visit/mysql_schemas.sql
deleted file mode 100644
index 0c16a9c57..000000000
--- a/problems/number-of-transactions-per-visit/mysql_schemas.sql
+++ /dev/null
@@ -1,22 +0,0 @@
-Create table If Not Exists Visits (user_id int, visit_date date);
-Create table If Not Exists Transactions (user_id int, transaction_date date, amount int);
-Truncate table Visits;
-insert into Visits (user_id, visit_date) values ('1', '2020-01-01');
-insert into Visits (user_id, visit_date) values ('2', '2020-01-02');
-insert into Visits (user_id, visit_date) values ('12', '2020-01-01');
-insert into Visits (user_id, visit_date) values ('19', '2020-01-03');
-insert into Visits (user_id, visit_date) values ('1', '2020-01-02');
-insert into Visits (user_id, visit_date) values ('2', '2020-01-03');
-insert into Visits (user_id, visit_date) values ('1', '2020-01-04');
-insert into Visits (user_id, visit_date) values ('7', '2020-01-11');
-insert into Visits (user_id, visit_date) values ('9', '2020-01-25');
-insert into Visits (user_id, visit_date) values ('8', '2020-01-28');
-Truncate table Transactions;
-insert into Transactions (user_id, transaction_date, amount) values ('1', '2020-01-02', '120');
-insert into Transactions (user_id, transaction_date, amount) values ('2', '2020-01-03', '22');
-insert into Transactions (user_id, transaction_date, amount) values ('7', '2020-01-11', '232');
-insert into Transactions (user_id, transaction_date, amount) values ('1', '2020-01-04', '7');
-insert into Transactions (user_id, transaction_date, amount) values ('9', '2020-01-25', '33');
-insert into Transactions (user_id, transaction_date, amount) values ('9', '2020-01-25', '66');
-insert into Transactions (user_id, transaction_date, amount) values ('8', '2020-01-28', '1');
-insert into Transactions (user_id, transaction_date, amount) values ('9', '2020-01-25', '99');
diff --git a/problems/number-of-trusted-contacts-of-a-customer/README.md b/problems/number-of-trusted-contacts-of-a-customer/README.md
deleted file mode 100644
index fc43743ce..000000000
--- a/problems/number-of-trusted-contacts-of-a-customer/README.md
+++ /dev/null
@@ -1,114 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-multiple-of-three "Largest Multiple of Three")
-　　　　　　　　　　　　　　　　
-[Next >](../how-many-numbers-are-smaller-than-the-current-number "How Many Numbers Are Smaller Than the Current Number")
-
-## [1364. Number of Trusted Contacts of a Customer (Medium)](https://leetcode.com/problems/number-of-trusted-contacts-of-a-customer "顾客的可信联系人数量")
-
-<p>Table: <code>Customers</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| customer_id   | int     |
-| customer_name | varchar |
-| email         | varchar |
-+---------------+---------+
-customer_id is the primary key for this table.
-Each row of this table contains the name and the email of a customer of an online shop.
-</pre>
- 
-<p>Table: <code>Contacts</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| user_id       | id      |
-| contact_name  | varchar |
-| contact_email | varchar |
-+---------------+---------+
-(user_id, contact_email) is the primary key for this table.
-Each row of this table contains the name and email of one contact of customer with user_id.
-This table contains information about people each customer trust. The contact may or may not exist in the Customers table.
-</pre>
-
-<p>Table: <code>Invoices</code></p>
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| invoice_id   | int     |
-| price        | int     |
-| user_id      | int     |
-+--------------+---------+
-invoice_id is the primary key for this table.
-Each row of this table indicates that user_id has an invoice with invoice_id and a price.
-</pre>
- 
-Write an SQL query to find the following for each invoice_id:
-
-- customer_name: The name of the customer the invoice is related to.
-- price: The price of the invoice.
-- contacts_cnt: The number of contacts related to the customer.
-- trusted_contacts_cnt: The number of contacts related to the customer and at the same time they are customers to the shop. (i.e His/Her email exists in the Customers table.)
-
-Order the result table by invoice_id.
-
-The query result format is in the following example:
-<pre>
-Customers table:
-+-------------+---------------+--------------------+
-| customer_id | customer_name | email              |
-+-------------+---------------+--------------------+
-| 1           | Alice         | alice@leetcode.com |
-| 2           | Bob           | bob@leetcode.com   |
-| 13          | John          | john@leetcode.com  |
-| 6           | Alex          | alex@leetcode.com  |
-+-------------+---------------+--------------------+
-Contacts table:
-+-------------+--------------+--------------------+
-| user_id     | contact_name | contact_email      |
-+-------------+--------------+--------------------+
-| 1           | Bob          | bob@leetcode.com   |
-| 1           | John         | john@leetcode.com  |
-| 1           | Jal          | jal@leetcode.com   |
-| 2           | Omar         | omar@leetcode.com  |
-| 2           | Meir         | meir@leetcode.com  |
-| 6           | Alice        | alice@leetcode.com |
-+-------------+--------------+--------------------+
-Invoices table:
-+------------+-------+---------+
-| invoice_id | price | user_id |
-+------------+-------+---------+
-| 77         | 100   | 1       |
-| 88         | 200   | 1       |
-| 99         | 300   | 2       |
-| 66         | 400   | 2       |
-| 55         | 500   | 13      |
-| 44         | 60    | 6       |
-+------------+-------+---------+
-Result table:
-+------------+---------------+-------+--------------+----------------------+
-| invoice_id | customer_name | price | contacts_cnt | trusted_contacts_cnt |
-+------------+---------------+-------+--------------+----------------------+
-| 44         | Alex          | 60    | 1            | 1                    |
-| 55         | John          | 500   | 0            | 0                    |
-| 66         | Bob           | 400   | 2            | 0                    |
-| 77         | Alice         | 100   | 3            | 2                    |
-| 88         | Alice         | 200   | 3            | 2                    |
-| 99         | Bob           | 300   | 2            | 0                    |
-+------------+---------------+-------+--------------+----------------------+
-Alice has three contacts, two of them are trusted contacts (Bob and John).
-Bob has two contacts, none of them is a trusted contact.
-Alex has one contact and it is a trusted contact (Alice).
-John doesn't have any contacts.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/number-of-trusted-contacts-of-a-customer/mysql_schemas.sql b/problems/number-of-trusted-contacts-of-a-customer/mysql_schemas.sql
deleted file mode 100644
index 608197d7b..000000000
--- a/problems/number-of-trusted-contacts-of-a-customer/mysql_schemas.sql
+++ /dev/null
@@ -1,22 +0,0 @@
-Create table If Not Exists Customers (customer_id int, customer_name varchar(20), email varchar(30));
-Create table If Not Exists Contacts (user_id int, contact_name varchar(20), contact_email varchar(30));
-Create table If Not Exists Invoices (invoice_id int, price int, user_id int);
-Truncate table Customers;
-insert into Customers (customer_id, customer_name, email) values ('1', 'Alice', 'alice@leetcode.com');
-insert into Customers (customer_id, customer_name, email) values ('2', 'Bob', 'bob@leetcode.com');
-insert into Customers (customer_id, customer_name, email) values ('13', 'John', 'john@leetcode.com');
-insert into Customers (customer_id, customer_name, email) values ('6', 'Alex', 'alex@leetcode.com');
-Truncate table Contacts;
-insert into Contacts (user_id, contact_name, contact_email) values ('1', 'Bob', 'bob@leetcode.com');
-insert into Contacts (user_id, contact_name, contact_email) values ('1', 'John', 'john@leetcode.com');
-insert into Contacts (user_id, contact_name, contact_email) values ('1', 'Jal', 'jal@leetcode.com');
-insert into Contacts (user_id, contact_name, contact_email) values ('2', 'Omar', 'omar@leetcode.com');
-insert into Contacts (user_id, contact_name, contact_email) values ('2', 'Meir', 'meir@leetcode.com');
-insert into Contacts (user_id, contact_name, contact_email) values ('6', 'Alice', 'alice@leetcode.com');
-Truncate table Invoices;
-insert into Invoices (invoice_id, price, user_id) values ('77', '100', '1');
-insert into Invoices (invoice_id, price, user_id) values ('88', '200', '1');
-insert into Invoices (invoice_id, price, user_id) values ('99', '300', '2');
-insert into Invoices (invoice_id, price, user_id) values ('66', '400', '2');
-insert into Invoices (invoice_id, price, user_id) values ('55', '500', '13');
-insert into Invoices (invoice_id, price, user_id) values ('44', '60', '6');
diff --git a/problems/number-of-unique-flavors-after-sharing-k-candies/README.md b/problems/number-of-unique-flavors-after-sharing-k-candies/README.md
deleted file mode 100644
index e77956fbe..000000000
--- a/problems/number-of-unique-flavors-after-sharing-k-candies/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-fruits-harvested-after-at-most-k-steps "Maximum Fruits Harvested After at Most K Steps")
-　　　　　　　　　　　　　　　　
-[Next >](../find-first-palindromic-string-in-the-array "Find First Palindromic String in the Array")
-
-## [2107. Number of Unique Flavors After Sharing K Candies (Medium)](https://leetcode.com/problems/number-of-unique-flavors-after-sharing-k-candies "")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For every group of k consecutive candies, count the number of unique flavors not inside that group. Return the largest number of unique flavors.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When calculating an adjacent group of k consecutive candies, can you use some of your previous calculations?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use a sliding window where the window is the group of k consecutive candies you are sharing. Use a hash map to store the number of candies of each type you can keep.
-</details>
diff --git a/problems/number-of-unique-good-subsequences/README.md b/problems/number-of-unique-good-subsequences/README.md
deleted file mode 100644
index 7a678c170..000000000
--- a/problems/number-of-unique-good-subsequences/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-work-sessions-to-finish-the-tasks "Minimum Number of Work Sessions to Finish the Tasks")
-　　　　　　　　　　　　　　　　
-[Next >](../find-cutoff-score-for-each-school "Find Cutoff Score for Each School")
-
-## [1987. Number of Unique Good Subsequences (Hard)](https://leetcode.com/problems/number-of-unique-good-subsequences "不同的好子序列数目")
-
-<p>You are given a binary string <code>binary</code>. A <strong>subsequence</strong> of <code>binary</code> is considered <strong>good</strong> if it is <strong>not empty</strong> and has <strong>no leading zeros</strong> (with the exception of <code>&quot;0&quot;</code>).</p>
-
-<p>Find the number of <strong>unique good subsequences</strong> of <code>binary</code>.</p>
-
-<ul>
-	<li>For example, if <code>binary = &quot;001&quot;</code>, then all the <strong>good</strong> subsequences are <code>[&quot;0&quot;, &quot;0&quot;, &quot;1&quot;]</code>, so the <strong>unique</strong> good subsequences are <code>&quot;0&quot;</code> and <code>&quot;1&quot;</code>. Note that subsequences <code>&quot;00&quot;</code>, <code>&quot;01&quot;</code>, and <code>&quot;001&quot;</code> are not good because they have leading zeros.</li>
-</ul>
-
-<p>Return <em>the number of <strong>unique good subsequences</strong> of </em><code>binary</code>. Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>A <strong>subsequence</strong> is a sequence that can be derived from another sequence by deleting some or no elements without changing the order of the remaining elements.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> binary = &quot;001&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The good subsequences of binary are [&quot;0&quot;, &quot;0&quot;, &quot;1&quot;].
-The unique good subsequences are &quot;0&quot; and &quot;1&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> binary = &quot;11&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The good subsequences of binary are [&quot;1&quot;, &quot;1&quot;, &quot;11&quot;].
-The unique good subsequences are &quot;1&quot; and &quot;11&quot;.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> binary = &quot;101&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The good subsequences of binary are [&quot;1&quot;, &quot;0&quot;, &quot;1&quot;, &quot;10&quot;, &quot;11&quot;, &quot;101&quot;]. 
-The unique good subsequences are &quot;0&quot;, &quot;1&quot;, &quot;10&quot;, &quot;11&quot;, and &quot;101&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= binary.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>binary</code> consists of only <code>&#39;0&#39;</code>s and <code>&#39;1&#39;</code>s.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The number of unique good subsequences is equal to the number of unique decimal values there are for all possible subsequences.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the answer at each index based on the previous indexes' answers.
-</details>
diff --git a/problems/number-of-valid-move-combinations-on-chessboard/README.md b/problems/number-of-valid-move-combinations-on-chessboard/README.md
deleted file mode 100644
index 89549528a..000000000
--- a/problems/number-of-valid-move-combinations-on-chessboard/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../plates-between-candles "Plates Between Candles")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-index-with-equal-value "Smallest Index With Equal Value")
-
-## [2056. Number of Valid Move Combinations On Chessboard (Hard)](https://leetcode.com/problems/number-of-valid-move-combinations-on-chessboard "棋盘上有效移动组合的数目")
-
-<p>There is an <code>8 x 8</code> chessboard containing <code>n</code> pieces (rooks, queens, or bishops). You are given a string array <code>pieces</code> of length <code>n</code>, where <code>pieces[i]</code> describes the type (rook, queen, or bishop) of the <code>i<sup>th</sup></code> piece. In addition, you are given a 2D integer array <code>positions</code> also of length <code>n</code>, where <code>positions[i] = [r<sub>i</sub>, c<sub>i</sub>]</code> indicates that the <code>i<sup>th</sup></code> piece is currently at the <strong>1-based</strong> coordinate <code>(r<sub>i</sub>, c<sub>i</sub>)</code> on the chessboard.</p>
-
-<p>When making a <strong>move</strong> for a piece, you choose a <strong>destination</strong> square that the piece will travel toward and stop on.</p>
-
-<ul>
-	<li>A rook can only travel <strong>horizontally or vertically</strong> from <code>(r, c)</code> to the direction of <code>(r+1, c)</code>, <code>(r-1, c)</code>, <code>(r, c+1)</code>, or <code>(r, c-1)</code>.</li>
-	<li>A queen can only travel <strong>horizontally, vertically, or diagonally</strong> from <code>(r, c)</code> to the direction of <code>(r+1, c)</code>, <code>(r-1, c)</code>, <code>(r, c+1)</code>, <code>(r, c-1)</code>, <code>(r+1, c+1)</code>, <code>(r+1, c-1)</code>, <code>(r-1, c+1)</code>, <code>(r-1, c-1)</code>.</li>
-	<li>A bishop can only travel <strong>diagonally</strong> from <code>(r, c)</code> to the direction of <code>(r+1, c+1)</code>, <code>(r+1, c-1)</code>, <code>(r-1, c+1)</code>, <code>(r-1, c-1)</code>.</li>
-</ul>
-
-<p>You must make a <strong>move</strong> for every piece on the board simultaneously. A <strong>move combination</strong> consists of all the <strong>moves</strong> performed on all the given pieces. Every second, each piece will instantaneously travel <strong>one square</strong> towards their destination if they are not already at it. All pieces start traveling at the <code>0<sup>th</sup></code> second. A move combination is <strong>invalid</strong> if, at a given time, <strong>two or more</strong> pieces occupy the same square.</p>
-
-<p>Return <em>the number of <strong>valid</strong> move combinations</em>​​​​​.</p>
-
-<p><strong>Notes:</strong></p>
-
-<ul>
-	<li><strong>No two pieces</strong> will start in the<strong> same</strong> square.</li>
-	<li>You may choose the square a piece is already on as its <strong>destination</strong>.</li>
-	<li>If two pieces are <strong>directly adjacent</strong> to each other, it is valid for them to <strong>move past each other</strong> and swap positions in one second.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/23/a1.png" style="width: 215px; height: 215px;" />
-<pre>
-<strong>Input:</strong> pieces = [&quot;rook&quot;], positions = [[1,1]]
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> The image above shows the possible squares the piece can move to.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/23/a2.png" style="width: 215px; height: 215px;" />
-<pre>
-<strong>Input:</strong> pieces = [&quot;queen&quot;], positions = [[1,1]]
-<strong>Output:</strong> 22
-<strong>Explanation:</strong> The image above shows the possible squares the piece can move to.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/23/a3.png" style="width: 214px; height: 215px;" />
-<pre>
-<strong>Input:</strong> pieces = [&quot;bishop&quot;], positions = [[4,3]]
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> The image above shows the possible squares the piece can move to.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == pieces.length </code></li>
-	<li><code>n == positions.length</code></li>
-	<li><code>1 &lt;= n &lt;= 4</code></li>
-	<li><code>pieces</code> only contains the strings <code>&quot;rook&quot;</code>, <code>&quot;queen&quot;</code>, and <code>&quot;bishop&quot;</code>.</li>
-	<li>There will be at most one queen on the chessboard.</li>
-	<li><code>1 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 8</code></li>
-	<li>Each <code>positions[i]</code> is distinct.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-N is small, we can generate all possible move combinations.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each possible move combination, determine which ones are valid.
-</details>
diff --git a/problems/number-of-valid-subarrays/README.md b/problems/number-of-valid-subarrays/README.md
deleted file mode 100644
index 0a0bdd5a5..000000000
--- a/problems/number-of-valid-subarrays/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-repeating-substring "Longest Repeating Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../fixed-point "Fixed Point")
-
-## [1063. Number of Valid Subarrays (Hard)](https://leetcode.com/problems/number-of-valid-subarrays "有效子数组的数目")
-
-<p>Given an array <code>A</code> of integers, return the number of <strong>non-empty continuous subarrays</strong> that satisfy the following condition:</p>
-
-<p>The leftmost element of the subarray is not larger than other elements in the subarray.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[1,4,2,5,3]</span>
-<strong>Output: </strong><span id="example-output-1">11</span>
-<strong>Explanation: </strong>There are 11 valid subarrays: [1],[4],[2],[5],[3],[1,4],[2,5],[1,4,2],[2,5,3],[1,4,2,5],[1,4,2,5,3].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">[3,2,1]</span>
-<strong>Output: </strong><span id="example-output-2">3</span>
-<strong>Explanation: </strong>The 3 valid subarrays are: [3],[2],[1].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-3-1">[2,2,2]</span>
-<strong>Output: </strong><span id="example-output-3">6</span>
-<strong>Explanation: </strong>There are 6 valid subarrays: [2],[2],[2],[2,2],[2,2],[2,2,2].
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= A.length &lt;= 50000</code></li>
-	<li><code>0 &lt;= A[i] &lt;= 100000</code></li>
-</ol>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Given a data structure that answers queries of the type to find the minimum in a range of an array (Range minimum query (RMQ) sparse table) in O(1) time. How can you solve this problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each starting index do a binary search with an RMQ to find the ending possible position.
-</details>
diff --git a/problems/number-of-valid-words-for-each-puzzle/README.md b/problems/number-of-valid-words-for-each-puzzle/README.md
deleted file mode 100644
index 32cfedc50..000000000
--- a/problems/number-of-valid-words-for-each-puzzle/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../can-make-palindrome-from-substring "Can Make Palindrome from Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../reformat-department-table "Reformat Department Table")
-
-## [1178. Number of Valid Words for Each Puzzle (Hard)](https://leetcode.com/problems/number-of-valid-words-for-each-puzzle "猜字谜")
-
-With respect to a given <code>puzzle</code> string, a <code>word</code> is <em>valid</em> if both the following conditions are satisfied:
-<ul>
-	<li><code>word</code> contains the first letter of <code>puzzle</code>.</li>
-	<li>For each letter in <code>word</code>, that letter is in <code>puzzle</code>.
-	<ul>
-		<li>For example, if the puzzle is <code>&quot;abcdefg&quot;</code>, then valid words are <code>&quot;faced&quot;</code>, <code>&quot;cabbage&quot;</code>, and <code>&quot;baggage&quot;</code>, while</li>
-		<li>invalid words are <code>&quot;beefed&quot;</code> (does not include <code>&#39;a&#39;</code>) and <code>&quot;based&quot;</code> (includes <code>&#39;s&#39;</code> which is not in the puzzle).</li>
-	</ul>
-	</li>
-</ul>
-Return <em>an array </em><code>answer</code><em>, where </em><code>answer[i]</code><em> is the number of words in the given word list </em><code>words</code><em> that is valid with respect to the puzzle </em><code>puzzles[i]</code>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;aaaa&quot;,&quot;asas&quot;,&quot;able&quot;,&quot;ability&quot;,&quot;actt&quot;,&quot;actor&quot;,&quot;access&quot;], puzzles = [&quot;aboveyz&quot;,&quot;abrodyz&quot;,&quot;abslute&quot;,&quot;absoryz&quot;,&quot;actresz&quot;,&quot;gaswxyz&quot;]
-<strong>Output:</strong> [1,1,3,2,4,0]
-<strong>Explanation:</strong> 
-1 valid word for &quot;aboveyz&quot; : &quot;aaaa&quot; 
-1 valid word for &quot;abrodyz&quot; : &quot;aaaa&quot;
-3 valid words for &quot;abslute&quot; : &quot;aaaa&quot;, &quot;asas&quot;, &quot;able&quot;
-2 valid words for &quot;absoryz&quot; : &quot;aaaa&quot;, &quot;asas&quot;
-4 valid words for &quot;actresz&quot; : &quot;aaaa&quot;, &quot;asas&quot;, &quot;actt&quot;, &quot;access&quot;
-There are no valid words for &quot;gaswxyz&quot; cause none of the words in the list contains letter &#39;g&#39;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;apple&quot;,&quot;pleas&quot;,&quot;please&quot;], puzzles = [&quot;aelwxyz&quot;,&quot;aelpxyz&quot;,&quot;aelpsxy&quot;,&quot;saelpxy&quot;,&quot;xaelpsy&quot;]
-<strong>Output:</strong> [0,1,3,2,0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>4 &lt;= words[i].length &lt;= 50</code></li>
-	<li><code>1 &lt;= puzzles.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>puzzles[i].length == 7</code></li>
-	<li><code>words[i]</code> and <code>puzzles[i]</code> consist of lowercase English letters.</li>
-	<li>Each <code>puzzles[i] </code>does not contain repeated characters.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Exploit the fact that the length of the puzzle is only 7.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use bit-masks to represent the word and puzzle strings.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For each puzzle, count the number of words whose bit-mask is a sub-mask of the puzzle's bit-mask.
-</details>
diff --git a/problems/number-of-valid-words-in-a-sentence/README.md b/problems/number-of-valid-words-in-a-sentence/README.md
deleted file mode 100644
index 6687e6bd5..000000000
--- a/problems/number-of-valid-words-in-a-sentence/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-linked-list-already-sorted-using-absolute-values "Sort Linked List Already Sorted Using Absolute Values")
-　　　　　　　　　　　　　　　　
-[Next >](../next-greater-numerically-balanced-number "Next Greater Numerically Balanced Number")
-
-## [2047. Number of Valid Words in a Sentence (Easy)](https://leetcode.com/problems/number-of-valid-words-in-a-sentence "句子中的有效单词数")
-
-<p>A sentence consists of lowercase letters (<code>&#39;a&#39;</code> to <code>&#39;z&#39;</code>), digits (<code>&#39;0&#39;</code> to <code>&#39;9&#39;</code>), hyphens (<code>&#39;-&#39;</code>), punctuation marks (<code>&#39;!&#39;</code>, <code>&#39;.&#39;</code>, and <code>&#39;,&#39;</code>), and spaces (<code>&#39; &#39;</code>) only. Each sentence can be broken down into <strong>one or more tokens</strong> separated by one or more spaces <code>&#39; &#39;</code>.</p>
-
-<p>A token is a valid word if <strong>all three</strong> of the following are true:</p>
-
-<ul>
-	<li>It only contains lowercase letters, hyphens, and/or punctuation (<strong>no</strong> digits).</li>
-	<li>There is <strong>at most one</strong> hyphen <code>&#39;-&#39;</code>. If present, it <strong>must</strong> be surrounded by lowercase characters (<code>&quot;a-b&quot;</code> is valid, but <code>&quot;-ab&quot;</code> and <code>&quot;ab-&quot;</code> are not valid).</li>
-	<li>There is <strong>at most one</strong> punctuation mark. If present, it <strong>must</strong> be at the <strong>end</strong> of the token (<code>&quot;ab,&quot;</code>, <code>&quot;cd!&quot;</code>, and <code>&quot;.&quot;</code> are valid, but <code>&quot;a!b&quot;</code> and <code>&quot;c.,&quot;</code> are not valid).</li>
-</ul>
-
-<p>Examples of valid words include <code>&quot;a-b.&quot;</code>, <code>&quot;afad&quot;</code>, <code>&quot;ba-c&quot;</code>, <code>&quot;a!&quot;</code>, and <code>&quot;!&quot;</code>.</p>
-
-<p>Given a string <code>sentence</code>, return <em>the <strong>number</strong> of valid words in </em><code>sentence</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence = &quot;<u>cat</u> <u>and</u>  <u>dog</u>&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The valid words in the sentence are &quot;cat&quot;, &quot;and&quot;, and &quot;dog&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence = &quot;!this  1-s b8d!&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no valid words in the sentence.
-&quot;!this&quot; is invalid because it starts with a punctuation mark.
-&quot;1-s&quot; and &quot;b8d&quot; are invalid because they contain digits.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence = &quot;<u>alice</u> <u>and</u>  <u>bob</u> <u>are</u> <u>playing</u> stone-game10&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The valid words in the sentence are &quot;alice&quot;, &quot;and&quot;, &quot;bob&quot;, &quot;are&quot;, and &quot;playing&quot;.
-&quot;stone-game10&quot; is invalid because it contains digits.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= sentence.length &lt;= 1000</code></li>
-	<li><code>sentence</code> only contains lowercase English letters, digits, <code>&#39; &#39;</code>, <code>&#39;-&#39;</code>, <code>&#39;!&#39;</code>, <code>&#39;.&#39;</code>, and <code>&#39;,&#39;</code>.</li>
-	<li>There will be at least&nbsp;<code>1</code> token.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Iterate through the string to split it by spaces.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Count the number of characters of each type (letters, numbers, hyphens, and punctuations).
-</details>
diff --git a/problems/number-of-visible-people-in-a-queue/README.md b/problems/number-of-visible-people-in-a-queue/README.md
deleted file mode 100644
index 0cf9c4819..000000000
--- a/problems/number-of-visible-people-in-a-queue/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../describe-the-painting "Describe the Painting")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-digits-of-string-after-convert "Sum of Digits of String After Convert")
-
-## [1944. Number of Visible People in a Queue (Hard)](https://leetcode.com/problems/number-of-visible-people-in-a-queue "队列中可以看到的人数")
-
-<p>There are <code>n</code> people standing in a queue, and they numbered from <code>0</code> to <code>n - 1</code> in <strong>left to right</strong> order. You are given an array <code>heights</code> of <strong>distinct</strong> integers where <code>heights[i]</code> represents the height of the <code>i<sup>th</sup></code> person.</p>
-
-<p>A person can <strong>see</strong> another person to their right in the queue if everybody in between is <strong>shorter</strong> than both of them. More formally, the <code>i<sup>th</sup></code> person can see the <code>j<sup>th</sup></code> person if <code>i &lt; j</code> and <code>min(heights[i], heights[j]) &gt; max(heights[i+1], heights[i+2], ..., heights[j-1])</code>.</p>
-
-<p>Return <em>an array </em><code>answer</code><em> of length </em><code>n</code><em> where </em><code>answer[i]</code><em> is the <strong>number of people</strong> the </em><code>i<sup>th</sup></code><em> person can <strong>see</strong> to their right in the queue</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/05/29/queue-plane.jpg" style="width: 600px; height: 247px;" /></p>
-
-<pre>
-<strong>Input:</strong> heights = [10,6,8,5,11,9]
-<strong>Output:</strong> [3,1,2,1,1,0]
-<strong>Explanation:</strong>
-Person 0 can see person 1, 2, and 4.
-Person 1 can see person 2.
-Person 2 can see person 3 and 4.
-Person 3 can see person 4.
-Person 4 can see person 5.
-Person 5 can see no one since nobody is to the right of them.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> heights = [5,1,2,3,10]
-<strong>Output:</strong> [4,1,1,1,0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == heights.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= heights[i] &lt;= 10<sup>5</sup></code></li>
-	<li>All the values of <code>heights</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to solve this problem in quadratic complexity ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For every subarray start at index i, keep finding new maximum values until a value larger than arr[i] is found.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Since the limits are high, you need a linear solution.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use a stack to keep the values of the array sorted as you iterate the array from the end to the start.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Keep popping from the stack the elements in sorted order until a value larger than arr[i] is found, these are the ones that person i can see.
-</details>
diff --git a/problems/number-of-ways-of-cutting-a-pizza/README.md b/problems/number-of-ways-of-cutting-a-pizza/README.md
deleted file mode 100644
index 67d6c62c9..000000000
--- a/problems/number-of-ways-of-cutting-a-pizza/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-time-to-collect-all-apples-in-a-tree "Minimum Time to Collect All Apples in a Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../apples-oranges "Apples & Oranges")
-
-## [1444. Number of Ways of Cutting a Pizza (Hard)](https://leetcode.com/problems/number-of-ways-of-cutting-a-pizza "切披萨的方案数")
-
-<p>Given a rectangular pizza represented as a <code>rows x cols</code>&nbsp;matrix containing the following characters: <code>&#39;A&#39;</code> (an apple) and <code>&#39;.&#39;</code> (empty cell) and given the integer <code>k</code>. You have to cut the pizza into <code>k</code> pieces using <code>k-1</code> cuts.&nbsp;</p>
-
-<p>For each cut you choose the direction: vertical or horizontal, then you choose a cut position at the cell boundary and cut the pizza into two pieces. If you cut the pizza vertically, give the left part of the pizza to a person. If you cut the pizza horizontally, give the upper part of the pizza to a person. Give the last piece of pizza to the last person.</p>
-
-<p><em>Return the number of ways of cutting the pizza such that each piece contains <strong>at least</strong> one apple.&nbsp;</em>Since the answer can be a huge number, return this modulo 10^9 + 7.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/04/23/ways_to_cut_apple_1.png" style="width: 500px; height: 378px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> pizza = [&quot;A..&quot;,&quot;AAA&quot;,&quot;...&quot;], k = 3
-<strong>Output:</strong> 3 
-<strong>Explanation:</strong> The figure above shows the three ways to cut the pizza. Note that pieces must contain at least one apple.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> pizza = [&quot;A..&quot;,&quot;AA.&quot;,&quot;...&quot;], k = 3
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> pizza = [&quot;A..&quot;,&quot;A..&quot;,&quot;...&quot;], k = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rows, cols &lt;= 50</code></li>
-	<li><code>rows ==&nbsp;pizza.length</code></li>
-	<li><code>cols ==&nbsp;pizza[i].length</code></li>
-	<li><code>1 &lt;= k &lt;= 10</code></li>
-	<li><code>pizza</code> consists of characters <code>&#39;A&#39;</code>&nbsp;and <code>&#39;.&#39;</code> only.</li>
-</ul>
-
-### Related Topics
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that after each cut the remaining piece of pizza always has the lower right coordinate at (rows-1,cols-1).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use dynamic programming approach with states (row1, col1, c) which computes the number of ways of cutting the pizza using "c" cuts where the current piece of pizza has upper left coordinate at (row1,col1) and lower right coordinate at (rows-1,cols-1).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For the transitions try all vertical and horizontal cuts such that the piece of pizza you have to give a person must contain at least one apple. The base case is when c=k-1.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Additionally use a 2D dynamic programming to respond in O(1) if a piece of pizza contains at least one apple.
-</details>
diff --git a/problems/number-of-ways-to-arrive-at-destination/README.md b/problems/number-of-ways-to-arrive-at-destination/README.md
deleted file mode 100644
index 84295ec95..000000000
--- a/problems/number-of-ways-to-arrive-at-destination/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-matrix-sum "Maximum Matrix Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-separate-numbers "Number of Ways to Separate Numbers")
-
-## [1976. Number of Ways to Arrive at Destination (Medium)](https://leetcode.com/problems/number-of-ways-to-arrive-at-destination "到达目的地的方案数")
-
-<p>You are in a city that consists of <code>n</code> intersections numbered from <code>0</code> to <code>n - 1</code> with <strong>bi-directional</strong> roads between some intersections. The inputs are generated such that you can reach any intersection from any other intersection and that there is at most one road between any two intersections.</p>
-
-<p>You are given an integer <code>n</code> and a 2D integer array <code>roads</code> where <code>roads[i] = [u<sub>i</sub>, v<sub>i</sub>, time<sub>i</sub>]</code> means that there is a road between intersections <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code> that takes <code>time<sub>i</sub></code> minutes to travel. You want to know in how many ways you can travel from intersection <code>0</code> to intersection <code>n - 1</code> in the <strong>shortest amount of time</strong>.</p>
-
-<p>Return <em>the <strong>number of ways</strong> you can arrive at your destination in the <strong>shortest amount of time</strong></em>. Since the answer may be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/17/graph2.png" style="width: 235px; height: 381px;" />
-<pre>
-<strong>Input:</strong> n = 7, roads = [[0,6,7],[0,1,2],[1,2,3],[1,3,3],[6,3,3],[3,5,1],[6,5,1],[2,5,1],[0,4,5],[4,6,2]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The shortest amount of time it takes to go from intersection 0 to intersection 6 is 7 minutes.
-The four ways to get there in 7 minutes are:
-- 0 ➝ 6
-- 0 ➝ 4 ➝ 6
-- 0 ➝ 1 ➝ 2 ➝ 5 ➝ 6
-- 0 ➝ 1 ➝ 3 ➝ 5 ➝ 6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, roads = [[1,0,10]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There is only one way to go from intersection 0 to intersection 1, and it takes 10 minutes.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 200</code></li>
-	<li><code>n - 1 &lt;= roads.length &lt;= n * (n - 1) / 2</code></li>
-	<li><code>roads[i].length == 3</code></li>
-	<li><code>0 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>1 &lt;= time<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>u<sub>i </sub>!= v<sub>i</sub></code></li>
-	<li>There is at most one road connecting any two intersections.</li>
-	<li>You can reach any intersection from any other intersection.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First use any shortest path algorithm to get edges where dist[u] + weight = dist[v], here dist[x] is the shortest distance between node 0 and x
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Using those edges only the graph turns into a dag now we just need to know the number of ways to get from node 0 to node n - 1 on a dag using dp
-</details>
diff --git a/problems/number-of-ways-to-divide-a-long-corridor/README.md b/problems/number-of-ways-to-divide-a-long-corridor/README.md
deleted file mode 100644
index 020172312..000000000
--- a/problems/number-of-ways-to-divide-a-long-corridor/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-highest-ranked-items-within-a-price-range "K Highest Ranked Items Within a Price Range")
-　　　　　　　　　　　　　　　　
-[Next >](../count-elements-with-strictly-smaller-and-greater-elements "Count Elements With Strictly Smaller and Greater Elements ")
-
-## [2147. Number of Ways to Divide a Long Corridor (Hard)](https://leetcode.com/problems/number-of-ways-to-divide-a-long-corridor "分隔长廊的方案数")
-
-<p>Along a long library corridor, there is a line of seats and decorative plants. You are given a <strong>0-indexed</strong> string <code>corridor</code> of length <code>n</code> consisting of letters <code>&#39;S&#39;</code> and <code>&#39;P&#39;</code> where each <code>&#39;S&#39;</code> represents a seat and each <code>&#39;P&#39;</code> represents a plant.</p>
-
-<p>One room divider has <strong>already</strong> been installed to the left of index <code>0</code>, and <strong>another</strong> to the right of index <code>n - 1</code>. Additional room dividers can be installed. For each position between indices <code>i - 1</code> and <code>i</code> (<code>1 &lt;= i &lt;= n - 1</code>), at most one divider can be installed.</p>
-
-<p>Divide the corridor into non-overlapping sections, where each section has <strong>exactly two seats</strong> with any number of plants. There may be multiple ways to perform the division. Two ways are <strong>different</strong> if there is a position with a room divider installed in the first way but not in the second way.</p>
-
-<p>Return <em>the number of ways to divide the corridor</em>. Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>. If there is no way, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/04/1.png" style="width: 410px; height: 199px;" />
-<pre>
-<strong>Input:</strong> corridor = &quot;SSPPSPS&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> There are 3 different ways to divide the corridor.
-The black bars in the above image indicate the two room dividers already installed.
-Note that in each of the ways, <strong>each</strong> section has exactly <strong>two</strong> seats.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/04/2.png" style="width: 357px; height: 68px;" />
-<pre>
-<strong>Input:</strong> corridor = &quot;PPSPSP&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There is only 1 way to divide the corridor, by not installing any additional dividers.
-Installing any would create some section that does not have exactly two seats.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/12/3.png" style="width: 115px; height: 68px;" />
-<pre>
-<strong>Input:</strong> corridor = &quot;S&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no way to divide the corridor because there will always be a section that does not have exactly two seats.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == corridor.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>corridor[i]</code> is either <code>&#39;S&#39;</code> or <code>&#39;P&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Divide the corridor into segments. Each segment has two seats, starts precisely with one seat, and ends precisely with the other seat.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How many dividers can you install between two adjacent segments? You must install precisely one. Otherwise, you would have created a section with not exactly two seats.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If there are k plants between two adjacent segments, there are k + 1 positions (ways) you could install the divider you must install.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The problem now becomes: Find the product of all possible positions between every two adjacent segments.
-</details>
diff --git a/problems/number-of-ways-to-form-a-target-string-given-a-dictionary/README.md b/problems/number-of-ways-to-form-a-target-string-given-a-dictionary/README.md
deleted file mode 100644
index 8ef01bd16..000000000
--- a/problems/number-of-ways-to-form-a-target-string-given-a-dictionary/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-substrings-that-differ-by-one-character "Count Substrings That Differ by One Character")
-　　　　　　　　　　　　　　　　
-[Next >](../check-array-formation-through-concatenation "Check Array Formation Through Concatenation")
-
-## [1639. Number of Ways to Form a Target String Given a Dictionary (Hard)](https://leetcode.com/problems/number-of-ways-to-form-a-target-string-given-a-dictionary "通过给定词典构造目标字符串的方案数")
-
-<p>You are given a list of strings of the <strong>same length</strong> <code>words</code> and a string <code>target</code>.</p>
-
-<p>Your task is to form <code>target</code> using the given <code>words</code> under the following rules:</p>
-
-<ul>
-	<li><code>target</code> should be formed from left to right.</li>
-	<li>To form the <code>i<sup>th</sup></code> character (<strong>0-indexed</strong>) of <code>target</code>, you can choose the <code>k<sup>th</sup></code> character of the <code>j<sup>th</sup></code> string in <code>words</code> if <code>target[i] = words[j][k]</code>.</li>
-	<li>Once you use the <code>k<sup>th</sup></code> character of the <code>j<sup>th</sup></code> string of <code>words</code>, you <strong>can no longer</strong> use the <code>x<sup>th</sup></code> character of any string in <code>words</code> where <code>x &lt;= k</code>. In other words, all characters to the left of or at index <code>k</code> become unusuable for every string.</li>
-	<li>Repeat the process until you form the string <code>target</code>.</li>
-</ul>
-
-<p><strong>Notice</strong> that you can use <strong>multiple characters</strong> from the <strong>same string</strong> in <code>words</code> provided the conditions above are met.</p>
-
-<p>Return <em>the number of ways to form <code>target</code> from <code>words</code></em>. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;acca&quot;,&quot;bbbb&quot;,&quot;caca&quot;], target = &quot;aba&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> There are 6 ways to form target.
-&quot;aba&quot; -&gt; index 0 (&quot;<u>a</u>cca&quot;), index 1 (&quot;b<u>b</u>bb&quot;), index 3 (&quot;cac<u>a</u>&quot;)
-&quot;aba&quot; -&gt; index 0 (&quot;<u>a</u>cca&quot;), index 2 (&quot;bb<u>b</u>b&quot;), index 3 (&quot;cac<u>a</u>&quot;)
-&quot;aba&quot; -&gt; index 0 (&quot;<u>a</u>cca&quot;), index 1 (&quot;b<u>b</u>bb&quot;), index 3 (&quot;acc<u>a</u>&quot;)
-&quot;aba&quot; -&gt; index 0 (&quot;<u>a</u>cca&quot;), index 2 (&quot;bb<u>b</u>b&quot;), index 3 (&quot;acc<u>a</u>&quot;)
-&quot;aba&quot; -&gt; index 1 (&quot;c<u>a</u>ca&quot;), index 2 (&quot;bb<u>b</u>b&quot;), index 3 (&quot;acc<u>a</u>&quot;)
-&quot;aba&quot; -&gt; index 1 (&quot;c<u>a</u>ca&quot;), index 2 (&quot;bb<u>b</u>b&quot;), index 3 (&quot;cac<u>a</u>&quot;)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;abba&quot;,&quot;baab&quot;], target = &quot;bab&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are 4 ways to form target.
-&quot;bab&quot; -&gt; index 0 (&quot;<u>b</u>aab&quot;), index 1 (&quot;b<u>a</u>ab&quot;), index 2 (&quot;ab<u>b</u>a&quot;)
-&quot;bab&quot; -&gt; index 0 (&quot;<u>b</u>aab&quot;), index 1 (&quot;b<u>a</u>ab&quot;), index 3 (&quot;baa<u>b</u>&quot;)
-&quot;bab&quot; -&gt; index 0 (&quot;<u>b</u>aab&quot;), index 2 (&quot;ba<u>a</u>b&quot;), index 3 (&quot;baa<u>b</u>&quot;)
-&quot;bab&quot; -&gt; index 1 (&quot;a<u>b</u>ba&quot;), index 2 (&quot;ba<u>a</u>b&quot;), index 3 (&quot;baa<u>b</u>&quot;)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 1000</code></li>
-	<li>All strings in <code>words</code> have the same length.</li>
-	<li><code>1 &lt;= target.length &lt;= 1000</code></li>
-	<li><code>words[i]</code> and <code>target</code> contain only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each index i, store the frequency of each character in the ith row.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use dynamic programing to calculate the number of ways to get the target string using the frequency array,
-</details>
diff --git a/problems/number-of-ways-to-paint-n-3-grid/README.md b/problems/number-of-ways-to-paint-n-3-grid/README.md
deleted file mode 100644
index aea32d531..000000000
--- a/problems/number-of-ways-to-paint-n-3-grid/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../html-entity-parser "HTML Entity Parser")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-quiet-students-in-all-exams "Find the Quiet Students in All Exams")
-
-## [1411. Number of Ways to Paint N × 3 Grid (Hard)](https://leetcode.com/problems/number-of-ways-to-paint-n-3-grid "给 N x 3 网格图涂色的方案数")
-
-<p>You have a <code>grid</code> of size <code>n x 3</code> and you want to paint each cell of the grid with exactly one of the three colors: <strong>Red</strong>, <strong>Yellow,</strong> or <strong>Green</strong> while making sure that no two adjacent cells have the same color (i.e., no two cells that share vertical or horizontal sides have the same color).</p>
-
-<p>Given <code>n</code> the number of rows of the grid, return <em>the number of ways</em> you can paint this <code>grid</code>. As the answer may grow large, the answer <strong>must be</strong> computed modulo <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/03/26/e1.png" style="width: 400px; height: 257px;" />
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> There are 12 possible way to paint the grid as shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5000
-<strong>Output:</strong> 30228214
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length</code></li>
-	<li><code>1 &lt;= n &lt;= 5000</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Painting a Grid With Three Different Colors](../painting-a-grid-with-three-different-colors) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We will use Dynamic programming approach. we will try all possible configuration.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let dp[idx][prev1col][prev2col][prev3col] be the number of ways to color the rows of the grid from idx to n-1 keeping in mind that the previous row (idx - 1) has colors prev1col, prev2col and prev3col. Build the dp array to get the answer.
-</details>
diff --git a/problems/number-of-ways-to-rearrange-sticks-with-k-sticks-visible/README.md b/problems/number-of-ways-to-rearrange-sticks-with-k-sticks-visible/README.md
deleted file mode 100644
index d107b5fdd..000000000
--- a/problems/number-of-ways-to-rearrange-sticks-with-k-sticks-visible/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../finding-pairs-with-a-certain-sum "Finding Pairs With a Certain Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../orders-with-maximum-quantity-above-average "Orders With Maximum Quantity Above Average")
-
-## [1866. Number of Ways to Rearrange Sticks With K Sticks Visible (Hard)](https://leetcode.com/problems/number-of-ways-to-rearrange-sticks-with-k-sticks-visible "恰有 K 根木棍可以看到的排列数目")
-
-<p>There are <code>n</code> uniquely-sized sticks whose lengths are integers from <code>1</code> to <code>n</code>. You want to arrange the sticks such that <strong>exactly</strong> <code>k</code>&nbsp;sticks are <strong>visible</strong> from the left. A stick&nbsp;is <strong>visible</strong> from the left if there are no <strong>longer</strong>&nbsp;sticks to the <strong>left</strong> of it.</p>
-
-<ul>
-	<li>For example, if the sticks are arranged <code>[<u>1</u>,<u>3</u>,2,<u>5</u>,4]</code>, then the sticks with lengths <code>1</code>, <code>3</code>, and <code>5</code> are visible from the left.</li>
-</ul>
-
-<p>Given <code>n</code> and <code>k</code>, return <em>the <strong>number</strong> of such arrangements</em>. Since the answer may be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 2
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> [<u>1</u>,<u>3</u>,2], [<u>2</u>,<u>3</u>,1], and [<u>2</u>,1,<u>3</u>] are the only arrangements such that exactly 2 sticks are visible.
-The visible sticks are underlined.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, k = 5
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> [<u>1</u>,<u>2</u>,<u>3</u>,<u>4</u>,<u>5</u>] is the only arrangement such that all 5 sticks are visible.
-The visible sticks are underlined.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 20, k = 11
-<strong>Output:</strong> 647427950
-<strong>Explanation:</strong> There are 647427950 (mod 10<sup>9 </sup>+ 7) ways to rearrange the sticks such that exactly 11 sticks are visible.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= k &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is there a way to build the solution from a base case?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How many ways are there if we fix the position of one stick?
-</details>
diff --git a/problems/number-of-ways-to-reconstruct-a-tree/README.md b/problems/number-of-ways-to-reconstruct-a-tree/README.md
deleted file mode 100644
index 11533af4f..000000000
--- a/problems/number-of-ways-to-reconstruct-a-tree/README.md
+++ /dev/null
@@ -1,100 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-the-lexicographically-largest-valid-sequence "Construct the Lexicographically Largest Valid Sequence")
-　　　　　　　　　　　　　　　　
-[Next >](../decode-xored-array "Decode XORed Array")
-
-## [1719. Number Of Ways To Reconstruct A Tree (Hard)](https://leetcode.com/problems/number-of-ways-to-reconstruct-a-tree "重构一棵树的方案数")
-
-<p>You are given an array <code>pairs</code>, where <code>pairs[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>, and:</p>
-
-<ul>
-	<li>There are no duplicates.</li>
-	<li><code>x<sub>i</sub> &lt; y<sub>i</sub></code></li>
-</ul>
-
-<p>Let <code>ways</code> be the number of rooted trees that satisfy the following conditions:</p>
-
-<ul>
-	<li>The tree consists of nodes whose values appeared in <code>pairs</code>.</li>
-	<li>A pair <code>[x<sub>i</sub>, y<sub>i</sub>]</code> exists in <code>pairs</code> <strong>if and only if</strong> <code>x<sub>i</sub></code> is an ancestor of <code>y<sub>i</sub></code> or <code>y<sub>i</sub></code> is an ancestor of <code>x<sub>i</sub></code>.</li>
-	<li><strong>Note:</strong> the tree does not have to be a binary tree.</li>
-</ul>
-
-<p>Two ways are considered to be different if there is at least one node that has different parents in both ways.</p>
-
-<p>Return:</p>
-
-<ul>
-	<li><code>0</code> if <code>ways == 0</code></li>
-	<li><code>1</code> if <code>ways == 1</code></li>
-	<li><code>2</code> if <code>ways &gt; 1</code></li>
-</ul>
-
-<p>A <strong>rooted tree</strong> is a tree that has a single root node, and all edges are oriented to be outgoing from the root.</p>
-
-<p>An <strong>ancestor</strong> of a node is any node on the path from the root to that node (excluding the node itself). The root has no ancestors.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://assets.leetcode.com/uploads/2020/12/03/trees2.png" style="width: 208px; height: 221px;" />
-<pre>
-<strong>Input:</strong> pairs = [[1,2],[2,3]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There is exactly one valid rooted tree, which is shown in the above figure.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/03/tree.png" style="width: 234px; height: 241px;" />
-<pre>
-<strong>Input:</strong> pairs = [[1,2],[2,3],[1,3]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are multiple valid rooted trees. Three of them are shown in the above figures.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> pairs = [[1,2],[2,3],[2,4],[1,5]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no valid rooted trees.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= pairs.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= x<sub>i </sub>&lt; y<sub>i</sub> &lt;= 500</code></li>
-	<li>The elements in <code>pairs</code> are unique.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think inductively. The first step is to get the root. Obviously, the root should be in pairs with all the nodes. If there isn't exactly one such node, then there are 0 ways.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The number of pairs involving a node must be less than or equal to that number of its parent.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Actually, if it's equal, then there is not exactly 1 way, because they can be swapped.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Recursively, given a set of nodes, get the node with the most pairs, then this must be a root and have no parents in the current set of nodes.
-</details>
diff --git a/problems/number-of-ways-to-reorder-array-to-get-same-bst/README.md b/problems/number-of-ways-to-reorder-array-to-get-same-bst/README.md
deleted file mode 100644
index 698d1d0ed..000000000
--- a/problems/number-of-ways-to-reorder-array-to-get-same-bst/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-days-to-disconnect-island "Minimum Number of Days to Disconnect Island")
-　　　　　　　　　　　　　　　　
-[Next >](../dot-product-of-two-sparse-vectors "Dot Product of Two Sparse Vectors")
-
-## [1569. Number of Ways to Reorder Array to Get Same BST (Hard)](https://leetcode.com/problems/number-of-ways-to-reorder-array-to-get-same-bst "将子数组重新排序得到同一个二叉查找树的方案数")
-
-<p>Given an array <code>nums</code> that represents a permutation of integers from <code>1</code> to <code>n</code>. We are going to construct a binary search tree (BST) by inserting the elements of <code>nums</code> in order into an initially empty BST. Find the number of different ways to reorder <code>nums</code> so that the constructed BST is identical to that formed from the original array <code>nums</code>.</p>
-
-<ul>
-	<li>For example, given <code>nums = [2,1,3]</code>, we will have 2 as the root, 1 as a left child, and 3 as a right child. The array <code>[2,3,1]</code> also yields the same BST but <code>[3,2,1]</code> yields a different BST.</li>
-</ul>
-
-<p>Return <em>the number of ways to reorder</em> <code>nums</code> <em>such that the BST formed is identical to the original BST formed from</em> <code>nums</code>.</p>
-
-<p>Since the answer may be very large, <strong>return it modulo </strong><code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/12/bb.png" style="width: 121px; height: 101px;" />
-<pre>
-<strong>Input:</strong> nums = [2,1,3]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> We can reorder nums to be [2,3,1] which will yield the same BST. There are no other ways to reorder nums which will yield the same BST.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/12/ex1.png" style="width: 241px; height: 161px;" />
-<pre>
-<strong>Input:</strong> nums = [3,4,5,1,2]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The following 5 arrays will yield the same BST: 
-[3,1,2,4,5]
-[3,1,4,2,5]
-[3,1,4,5,2]
-[3,4,1,2,5]
-[3,4,1,5,2]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/12/ex4.png" style="width: 121px; height: 161px;" />
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no other orderings of nums that will yield the same BST.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= nums.length</code></li>
-	<li>All integers in <code>nums</code> are <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a divide and conquer strategy.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The first number will always be the root. Consider the numbers smaller and larger than the root separately. When merging the results together, how many ways can you order x elements in x+y positions?
-</details>
diff --git a/problems/number-of-ways-to-separate-numbers/README.md b/problems/number-of-ways-to-separate-numbers/README.md
deleted file mode 100644
index 1d359dd07..000000000
--- a/problems/number-of-ways-to-separate-numbers/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-arrive-at-destination "Number of Ways to Arrive at Destination")
-　　　　　　　　　　　　　　　　
-[Next >](../employees-whose-manager-left-the-company "Employees Whose Manager Left the Company")
-
-## [1977. Number of Ways to Separate Numbers (Hard)](https://leetcode.com/problems/number-of-ways-to-separate-numbers "划分数字的方案数")
-
-<p>You wrote down many <strong>positive</strong> integers in a string called <code>num</code>. However, you realized that you forgot to add commas to seperate the different numbers. You remember that the list of integers was <strong>non-decreasing</strong> and that <strong>no</strong> integer had leading zeros.</p>
-
-<p>Return <em>the <strong>number of possible lists of integers</strong> that you could have written down to get the string </em><code>num</code>. Since the answer may be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;327&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> You could have written down the numbers:
-3, 27
-327
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;094&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> No numbers can have leading zeros and all numbers must be positive.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;0&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> No numbers can have leading zeros and all numbers must be positive.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num.length &lt;= 3500</code></li>
-	<li><code>num</code> consists of digits <code>&#39;0&#39;</code> through <code>&#39;9&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Suffix Array](../../tag/suffix-array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If we know the current number has d digits, how many digits can the previous number have?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is there a quick way of calculating the number of possibilities for the previous number if we know that it must have less than or equal to d digits? Try to do some pre-processing.
-</details>
diff --git a/problems/number-of-ways-to-split-a-string/README.md b/problems/number-of-ways-to-split-a-string/README.md
deleted file mode 100644
index 9874c1112..000000000
--- a/problems/number-of-ways-to-split-a-string/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../matrix-diagonal-sum "Matrix Diagonal Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-subarray-to-be-removed-to-make-array-sorted "Shortest Subarray to be Removed to Make Array Sorted")
-
-## [1573. Number of Ways to Split a String (Medium)](https://leetcode.com/problems/number-of-ways-to-split-a-string "分割字符串的方案数")
-
-<p>Given a binary string <code>s</code>, you can split <code>s</code> into 3 <strong>non-empty</strong> strings <code>s1</code>, <code>s2</code>, and <code>s3</code> where <code>s1 + s2 + s3 = s</code>.</p>
-
-<p>Return the number of ways <code>s</code> can be split such that the number of ones is the same in <code>s1</code>, <code>s2</code>, and <code>s3</code>. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;10101&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are four ways to split s in 3 parts where each part contain the same number of letters &#39;1&#39;.
-&quot;1|010|1&quot;
-&quot;1|01|01&quot;
-&quot;10|10|1&quot;
-&quot;10|1|01&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1001&quot;
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0000&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> There are three ways to split s in 3 parts.
-&quot;0|0|00&quot;
-&quot;0|00|0&quot;
-&quot;00|0|0&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Split Array with Equal Sum](../split-array-with-equal-sum) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There is no way if the sum (number of '1's) is not divisible by the number of splits. So sum%3 should be 0.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Preffix s1 , and suffix s3 should have sum/3 characters '1'.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Follow up: Can you generalize the problem with numbers between [-10^9, 10^9] such the sum between subarrays s1, s2, s3 are the same?
-</details>
diff --git a/problems/number-of-ways-to-stay-in-the-same-place-after-some-steps/README.md b/problems/number-of-ways-to-stay-in-the-same-place-after-some-steps/README.md
deleted file mode 100644
index 5dfd4cae6..000000000
--- a/problems/number-of-ways-to-stay-in-the-same-place-after-some-steps/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../search-suggestions-system "Search Suggestions System")
-　　　　　　　　　　　　　　　　
-[Next >](../all-people-report-to-the-given-manager "All People Report to the Given Manager")
-
-## [1269. Number of Ways to Stay in the Same Place After Some Steps (Hard)](https://leetcode.com/problems/number-of-ways-to-stay-in-the-same-place-after-some-steps "停在原地的方案数")
-
-<p>You have a pointer at index <code>0</code> in an array of size <code>arrLen</code>. At each step, you can move 1 position to the left, 1 position to the right in the array, or stay in the same place (The pointer should not be placed outside the array at any time).</p>
-
-<p>Given two integers <code>steps</code> and <code>arrLen</code>, return the number of ways such that your pointer still at index <code>0</code> after <strong>exactly</strong> <code>steps</code> steps. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> steps = 3, arrLen = 2
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>There are 4 differents ways to stay at index 0 after 3 steps.
-Right, Left, Stay
-Stay, Right, Left
-Right, Stay, Left
-Stay, Stay, Stay
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> steps = 2, arrLen = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are 2 differents ways to stay at index 0 after 2 steps
-Right, Left
-Stay, Stay
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> steps = 4, arrLen = 2
-<strong>Output:</strong> 8
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= steps &lt;= 500</code></li>
-	<li><code>1 &lt;= arrLen &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try with Dynamic programming, dp(pos,steps): number of ways to back pos = 0 using exactly "steps" moves.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Notice that the computational complexity does not depend of "arrlen".
-</details>
diff --git a/problems/number-of-ways-to-wear-different-hats-to-each-other/README.md b/problems/number-of-ways-to-wear-different-hats-to-each-other/README.md
deleted file mode 100644
index a5b016402..000000000
--- a/problems/number-of-ways-to-wear-different-hats-to-each-other/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-a-string-can-break-another-string "Check If a String Can Break Another String")
-　　　　　　　　　　　　　　　　
-[Next >](../create-a-session-bar-chart "Create a Session Bar Chart")
-
-## [1434. Number of Ways to Wear Different Hats to Each Other (Hard)](https://leetcode.com/problems/number-of-ways-to-wear-different-hats-to-each-other "每个人戴不同帽子的方案数")
-
-<p>There are <code>n</code> people and <code>40</code> types of hats labeled from <code>1</code> to <code>40</code>.</p>
-
-<p>Given a 2D integer array <code>hats</code>, where <code>hats[i]</code> is a list of all hats preferred by the <code>i<sup>th</sup></code> person.</p>
-
-<p>Return <em>the number of ways that the <code>n</code> people wear different hats to each other</em>.</p>
-
-<p>Since the answer may be too large, return it modulo <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> hats = [[3,4],[4,5],[5]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There is only one way to choose hats given the conditions. 
-First person choose hat 3, Second person choose hat 4 and last one hat 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> hats = [[3,5,1],[3,5]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are 4 ways to choose hats:
-(3,5), (5,3), (1,3) and (1,5)
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> hats = [[1,2,3,4],[1,2,3,4],[1,2,3,4],[1,2,3,4]]
-<strong>Output:</strong> 24
-<strong>Explanation:</strong> Each person can choose hats labeled from 1 to 4.
-Number of Permutations of (1,2,3,4) = 24.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == hats.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10</code></li>
-	<li><code>1 &lt;= hats[i].length &lt;= 40</code></li>
-	<li><code>1 &lt;= hats[i][j] &lt;= 40</code></li>
-	<li><code>hats[i]</code> contains a list of <strong>unique</strong> integers.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Similar Questions
-  1. [The Number of Good Subsets](../the-number-of-good-subsets) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Dynamic programming + bitmask.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-dp(peopleMask, idHat) number of ways to wear different hats given a bitmask (people visited) and used hats from 1 to idHat-1.
-</details>
diff --git a/problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers/README.md b/problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers/README.md
deleted file mode 100644
index 9a7b126db..000000000
--- a/problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../replace-all-s-to-avoid-consecutive-repeating-characters "Replace All ?'s to Avoid Consecutive Repeating Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-time-to-make-rope-colorful "Minimum Time to Make Rope Colorful")
-
-## [1577. Number of Ways Where Square of Number Is Equal to Product of Two Numbers (Medium)](https://leetcode.com/problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers "数的平方等于两数乘积的方法数")
-
-<p>Given two arrays of integers <code>nums1</code> and <code>nums2</code>, return the number of triplets formed (type 1 and type 2) under the following rules:</p>
-
-<ul>
-	<li>Type 1: Triplet (i, j, k) if <code>nums1[i]<sup>2</sup> == nums2[j] * nums2[k]</code> where <code>0 &lt;= i &lt; nums1.length</code> and <code>0 &lt;= j &lt; k &lt; nums2.length</code>.</li>
-	<li>Type 2: Triplet (i, j, k) if <code>nums2[i]<sup>2</sup> == nums1[j] * nums1[k]</code> where <code>0 &lt;= i &lt; nums2.length</code> and <code>0 &lt;= j &lt; k &lt; nums1.length</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [7,4], nums2 = [5,2,8,9]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Type 1: (1, 1, 2), nums1[1]<sup>2</sup> = nums2[1] * nums2[2]. (4<sup>2</sup> = 2 * 8). 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,1], nums2 = [1,1,1]
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> All Triplets are valid, because 1<sup>2</sup> = 1 * 1.
-Type 1: (0,0,1), (0,0,2), (0,1,2), (1,0,1), (1,0,2), (1,1,2).  nums1[i]<sup>2</sup> = nums2[j] * nums2[k].
-Type 2: (0,0,1), (1,0,1), (2,0,1). nums2[i]<sup>2</sup> = nums1[j] * nums1[k].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [7,7,8,3], nums2 = [1,2,9,7]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are 2 valid triplets.
-Type 1: (3,0,2).  nums1[3]<sup>2</sup> = nums2[0] * nums2[2].
-Type 2: (3,0,1).  nums2[3]<sup>2</sup> = nums1[0] * nums1[1].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums1[i], nums2[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Precalculate the frequencies of all nums1[i]^2 and nums2[i]^2
-</details>
diff --git a/problems/number-of-wonderful-substrings/README.md b/problems/number-of-wonderful-substrings/README.md
deleted file mode 100644
index 0c236f651..000000000
--- a/problems/number-of-wonderful-substrings/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cyclically-rotating-a-grid "Cyclically Rotating a Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../count-ways-to-build-rooms-in-an-ant-colony "Count Ways to Build Rooms in an Ant Colony")
-
-## [1915. Number of Wonderful Substrings (Medium)](https://leetcode.com/problems/number-of-wonderful-substrings "最美子字符串的数目")
-
-<p>A <strong>wonderful</strong> string is a string where <strong>at most one</strong> letter appears an <strong>odd</strong> number of times.</p>
-
-<ul>
-	<li>For example, <code>&quot;ccjjc&quot;</code> and <code>&quot;abab&quot;</code> are wonderful, but <code>&quot;ab&quot;</code> is not.</li>
-</ul>
-
-<p>Given a string <code>word</code> that consists of the first ten lowercase English letters (<code>&#39;a&#39;</code> through <code>&#39;j&#39;</code>), return <em>the <strong>number of wonderful non-empty substrings</strong> in </em><code>word</code><em>. If the same substring appears multiple times in </em><code>word</code><em>, then count <strong>each occurrence</strong> separately.</em></p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters in a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;aba&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The four wonderful substrings are underlined below:
-- &quot;<u><strong>a</strong></u>ba&quot; -&gt; &quot;a&quot;
-- &quot;a<u><strong>b</strong></u>a&quot; -&gt; &quot;b&quot;
-- &quot;ab<u><strong>a</strong></u>&quot; -&gt; &quot;a&quot;
-- &quot;<u><strong>aba</strong></u>&quot; -&gt; &quot;aba&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;aabb&quot;
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> The nine wonderful substrings are underlined below:
-- &quot;<strong><u>a</u></strong>abb&quot; -&gt; &quot;a&quot;
-- &quot;<u><strong>aa</strong></u>bb&quot; -&gt; &quot;aa&quot;
-- &quot;<u><strong>aab</strong></u>b&quot; -&gt; &quot;aab&quot;
-- &quot;<u><strong>aabb</strong></u>&quot; -&gt; &quot;aabb&quot;
-- &quot;a<u><strong>a</strong></u>bb&quot; -&gt; &quot;a&quot;
-- &quot;a<u><strong>abb</strong></u>&quot; -&gt; &quot;abb&quot;
-- &quot;aa<u><strong>b</strong></u>b&quot; -&gt; &quot;b&quot;
-- &quot;aa<u><strong>bb</strong></u>&quot; -&gt; &quot;bb&quot;
-- &quot;aab<u><strong>b</strong></u>&quot; -&gt; &quot;b&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;he&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The two wonderful substrings are underlined below:
-- &quot;<b><u>h</u></b>e&quot; -&gt; &quot;h&quot;
-- &quot;h<strong><u>e</u></strong>&quot; -&gt; &quot;e&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>word</code> consists of lowercase English letters from <code>&#39;a&#39;</code>&nbsp;to <code>&#39;j&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each prefix of the string, check which characters are of even frequency and which are not and represent it by a bitmask.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the other prefixes whose masks differs from the current prefix mask by at most one bit.
-</details>
diff --git a/problems/numbers-at-most-n-given-digit-set/README.md b/problems/numbers-at-most-n-given-digit-set/README.md
deleted file mode 100644
index fd2f7a8ae..000000000
--- a/problems/numbers-at-most-n-given-digit-set/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../online-stock-span "Online Stock Span")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-permutations-for-di-sequence "Valid Permutations for DI Sequence")
-
-## [902. Numbers At Most N Given Digit Set (Hard)](https://leetcode.com/problems/numbers-at-most-n-given-digit-set "最大为 N 的数字组合")
-
-<p>Given an array of <code>digits</code> which is sorted in <strong>non-decreasing</strong> order. You can write numbers using each <code>digits[i]</code> as many times as we want. For example, if <code>digits = [&#39;1&#39;,&#39;3&#39;,&#39;5&#39;]</code>, we may write numbers such as <code>&#39;13&#39;</code>, <code>&#39;551&#39;</code>, and <code>&#39;1351315&#39;</code>.</p>
-
-<p>Return <em>the number of positive integers that can be generated </em>that are less than or equal to a given integer <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [&quot;1&quot;,&quot;3&quot;,&quot;5&quot;,&quot;7&quot;], n = 100
-<strong>Output:</strong> 20
-<strong>Explanation: </strong>
-The 20 numbers that can be written are:
-1, 3, 5, 7, 11, 13, 15, 17, 31, 33, 35, 37, 51, 53, 55, 57, 71, 73, 75, 77.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [&quot;1&quot;,&quot;4&quot;,&quot;9&quot;], n = 1000000000
-<strong>Output:</strong> 29523
-<strong>Explanation: </strong>
-We can write 3 one digit numbers, 9 two digit numbers, 27 three digit numbers,
-81 four digit numbers, 243 five digit numbers, 729 six digit numbers,
-2187 seven digit numbers, 6561 eight digit numbers, and 19683 nine digit numbers.
-In total, this is 29523 integers that can be written using the digits array.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [&quot;7&quot;], n = 8
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= digits.length &lt;= 9</code></li>
-	<li><code>digits[i].length == 1</code></li>
-	<li><code>digits[i]</code> is a digit from&nbsp;<code>&#39;1&#39;</code>&nbsp;to <code>&#39;9&#39;</code>.</li>
-	<li>All the values in&nbsp;<code>digits</code> are <strong>unique</strong>.</li>
-	<li><code>digits</code> is sorted in&nbsp;<strong>non-decreasing</strong> order.</li>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/numbers-at-most-n-given-digit-set/numbers_at_most_n_given_digit_set.go b/problems/numbers-at-most-n-given-digit-set/numbers_at_most_n_given_digit_set.go
deleted file mode 100644
index 6a5b71a6d..000000000
--- a/problems/numbers-at-most-n-given-digit-set/numbers_at_most_n_given_digit_set.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem902
diff --git a/problems/numbers-at-most-n-given-digit-set/numbers_at_most_n_given_digit_set_test.go b/problems/numbers-at-most-n-given-digit-set/numbers_at_most_n_given_digit_set_test.go
deleted file mode 100644
index 6a5b71a6d..000000000
--- a/problems/numbers-at-most-n-given-digit-set/numbers_at_most_n_given_digit_set_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem902
diff --git a/problems/numbers-with-repeated-digits/README.md b/problems/numbers-with-repeated-digits/README.md
deleted file mode 100644
index 4d2f0738f..000000000
--- a/problems/numbers-with-repeated-digits/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../capacity-to-ship-packages-within-d-days "Capacity To Ship Packages Within D Days")
-　　　　　　　　　　　　　　　　
-[Next >](../partition-array-into-three-parts-with-equal-sum "Partition Array Into Three Parts With Equal Sum")
-
-## [1012. Numbers With Repeated Digits (Hard)](https://leetcode.com/problems/numbers-with-repeated-digits "至少有 1 位重复的数字")
-
-<p>Given an integer <code>n</code>, return <em>the number of positive integers in the range </em><code>[1, n]</code><em> that have <strong>at least one</strong> repeated digit</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 20
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only positive number (&lt;= 20) with at least 1 repeated digit is 11.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 100
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> The positive numbers (&lt;= 100) with atleast 1 repeated digit are 11, 22, 33, 44, 55, 66, 77, 88, 99, and 100.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1000
-<strong>Output:</strong> 262
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How many numbers with no duplicate digits?  How many numbers with K digits and no duplicates?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How many numbers with same length as N?  How many numbers with same prefix as N?
-</details>
diff --git a/problems/numbers-with-repeated-digits/numbers_with_repeated_digits.go b/problems/numbers-with-repeated-digits/numbers_with_repeated_digits.go
deleted file mode 100644
index 6097cd5c3..000000000
--- a/problems/numbers-with-repeated-digits/numbers_with_repeated_digits.go
+++ /dev/null
@@ -1,72 +0,0 @@
-package problem1012
-
-func numDupDigitsAtMostN(N int) int {
-	digits := convert(N + 1) // +1 为为了把判别条件从 <= 简化成 <
-	bits := len(digits)
-
-	noRepeat := 0
-	// 统计宽度短于 N 的不含重复数字的数的个数
-	for b := 1; b < bits; b++ {
-		noRepeat += 9 * count(9, b-1)
-	}
-
-	// 统计和 N 具有相同高位的且不含重复数字的数的个数
-	hasSeen := make(map[int]bool, 10)
-	for b := 0; b < bits; b++ {
-		d := 0
-		if b == 0 {
-			d = 1 // 最高位上的数字不能为 0
-		}
-		for ; d < digits[b]; d++ {
-			// 如果 hasSeen[d]=true
-			// 说明在更高位上已经出现过 d 了
-			// 无论低位上再出现什么，都不是 noRepeat 了
-			if !hasSeen[d] {
-				noRepeat += count(9-b, bits-b-1)
-			}
-		}
-		if hasSeen[digits[b]] {
-			// digits[:b+1] 中出现了重复的数字
-			// 不可能再有 noRepeat 了
-			break
-		}
-		hasSeen[digits[b]] = true
-	}
-	return N - noRepeat
-}
-
-func convert(N int) []int {
-	res := make([]int, 0, 10)
-	for N > 0 {
-		res = append(res, N%10)
-		N /= 10
-	}
-	swap(res)
-	return res
-}
-
-func swap(A []int) {
-	i, j := 0, len(A)-1
-	for i < j {
-		A[i], A[j] = A[j], A[i]
-		i++
-		j--
-	}
-}
-
-// 统计了 m 个数字组成宽度为 n 的数值时，
-// 不含重复数字的数值的个数。
-// 注意，
-// 真正使用 count 的时候，是为了统计 n+1 位宽度的数值
-// 在 n+1 位的最高位上不放置 0
-// 就可以保证剩下的 n 位的宽度确实是 n
-// 所以，count 在使用时，还需要乘上 n+1 位上可供选择的数字的个数
-// 例如， 9*count(9, i-1)  的实际含义才是，所有宽度为 i 且不包含重复数字的数值个数
-// 例如， count（8，i） 的实际含义是，以 X 开头所有宽度为 i+1 且不包含重复数字的数的个数
-//      X 可以是任意一个数字
-func count(m, n int) int {
-	if n == 0 {
-		return 1
-	}
-	return count(m, n-1) * (m - n + 1)
-}
diff --git a/problems/numbers-with-same-consecutive-differences/README.md b/problems/numbers-with-same-consecutive-differences/README.md
deleted file mode 100644
index b13d65569..000000000
--- a/problems/numbers-with-same-consecutive-differences/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../vowel-spellchecker "Vowel Spellchecker")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-cameras "Binary Tree Cameras")
-
-## [967. Numbers With Same Consecutive Differences (Medium)](https://leetcode.com/problems/numbers-with-same-consecutive-differences "连续差相同的数字")
-
-<p>Return all <strong>non-negative</strong> integers of length <code>n</code> such that the absolute difference between every two consecutive digits is <code>k</code>.</p>
-
-<p>Note that <strong>every</strong> number in the answer <strong>must not</strong> have leading zeros. For example, <code>01</code> has one leading zero and is invalid.</p>
-
-<p>You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 7
-<strong>Output:</strong> [181,292,707,818,929]
-<strong>Explanation:</strong> Note that 070 is not a valid number, because it has leading zeroes.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, k = 1
-<strong>Output:</strong> [10,12,21,23,32,34,43,45,54,56,65,67,76,78,87,89,98]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, k = 0
-<strong>Output:</strong> [11,22,33,44,55,66,77,88,99]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, k = 2
-<strong>Output:</strong> [13,20,24,31,35,42,46,53,57,64,68,75,79,86,97]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 9</code></li>
-	<li><code>0 &lt;= k &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
diff --git a/problems/numbers-with-same-consecutive-differences/numbers_with_same_consecutive_differences.go b/problems/numbers-with-same-consecutive-differences/numbers_with_same_consecutive_differences.go
deleted file mode 100644
index 0c7fbc14d..000000000
--- a/problems/numbers-with-same-consecutive-differences/numbers_with_same_consecutive_differences.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem967
diff --git a/problems/occurrences-after-bigram/README.md b/problems/occurrences-after-bigram/README.md
deleted file mode 100644
index 7bf9b45af..000000000
--- a/problems/occurrences-after-bigram/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../project-employees-iii "Project Employees III")
-　　　　　　　　　　　　　　　　
-[Next >](../letter-tile-possibilities "Letter Tile Possibilities")
-
-## [1078. Occurrences After Bigram (Easy)](https://leetcode.com/problems/occurrences-after-bigram "Bigram 分词")
-
-<p>Given two strings <code>first</code> and <code>second</code>, consider occurrences in some text of the form <code>&quot;first second third&quot;</code>, where <code>second</code> comes immediately after <code>first</code>, and <code>third</code> comes immediately after <code>second</code>.</p>
-
-<p>Return <em>an array of all the words</em> <code>third</code> <em>for each occurrence of</em> <code>&quot;first second third&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> text = "alice is a good girl she is a good student", first = "a", second = "good"
-<strong>Output:</strong> ["girl","student"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> text = "we will we will rock you", first = "we", second = "will"
-<strong>Output:</strong> ["we","rock"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= text.length &lt;= 1000</code></li>
-	<li><code>text</code> consists of lowercase English letters and spaces.</li>
-	<li>All the words in <code>text</code> a separated by <strong>a single space</strong>.</li>
-	<li><code>1 &lt;= first.length, second.length &lt;= 10</code></li>
-	<li><code>first</code> and <code>second</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Split the string into words, then look at adjacent triples of words.
-</details>
diff --git a/problems/occurrences-after-bigram/occurrences_after_bigram.go b/problems/occurrences-after-bigram/occurrences_after_bigram.go
deleted file mode 100644
index 8267aff9e..000000000
--- a/problems/occurrences-after-bigram/occurrences_after_bigram.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem1078
-
-import "strings"
-
-func findOcurrences(text string, first string, second string) []string {
-	words := strings.Split(text, " ")
-	n := len(words)
-	res := make([]string, 0, n)
-	for i := 0; i+2 < n; i++ {
-		if words[i] == first &&
-			words[i+1] == second {
-			res = append(res, words[i+2])
-		}
-	}
-	return res
-}
diff --git a/problems/odd-even-jump/README.md b/problems/odd-even-jump/README.md
deleted file mode 100644
index 43a345e2d..000000000
--- a/problems/odd-even-jump/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subarray-sums-divisible-by-k "Subarray Sums Divisible by K")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-perimeter-triangle "Largest Perimeter Triangle")
-
-## [975. Odd Even Jump (Hard)](https://leetcode.com/problems/odd-even-jump "奇偶跳")
-
-<p>You are given an integer array <code>arr</code>. From some starting index, you can make a series of jumps. The (1<sup>st</sup>, 3<sup>rd</sup>, 5<sup>th</sup>, ...) jumps in the series are called <strong>odd-numbered jumps</strong>, and the (2<sup>nd</sup>, 4<sup>th</sup>, 6<sup>th</sup>, ...) jumps in the series are called <strong>even-numbered jumps</strong>. Note that the <strong>jumps</strong> are numbered, not the indices.</p>
-
-<p>You may jump forward from index <code>i</code> to index <code>j</code> (with <code>i &lt; j</code>) in the following way:</p>
-
-<ul>
-	<li>During <strong>odd-numbered jumps</strong> (i.e., jumps 1, 3, 5, ...), you jump to the index <code>j</code> such that <code>arr[i] &lt;= arr[j]</code> and <code>arr[j]</code> is the smallest possible value. If there are multiple such indices <code>j</code>, you can only jump to the <strong>smallest</strong> such index <code>j</code>.</li>
-	<li>During <strong>even-numbered jumps</strong> (i.e., jumps 2, 4, 6, ...), you jump to the index <code>j</code> such that <code>arr[i] &gt;= arr[j]</code> and <code>arr[j]</code> is the largest possible value. If there are multiple such indices <code>j</code>, you can only jump to the <strong>smallest</strong> such index <code>j</code>.</li>
-	<li>It may be the case that for some index <code>i</code>, there are no legal jumps.</li>
-</ul>
-
-<p>A starting index is <strong>good</strong> if, starting from that index, you can reach the end of the array (index <code>arr.length - 1</code>) by jumping some number of times (possibly 0 or more than once).</p>
-
-<p>Return <em>the number of <strong>good</strong> starting indices</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [10,13,12,14,15]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-From starting index i = 0, we can make our 1st jump to i = 2 (since arr[2] is the smallest among arr[1], arr[2], arr[3], arr[4] that is greater or equal to arr[0]), then we cannot jump any more.
-From starting index i = 1 and i = 2, we can make our 1st jump to i = 3, then we cannot jump any more.
-From starting index i = 3, we can make our 1st jump to i = 4, so we have reached the end.
-From starting index i = 4, we have reached the end already.
-In total, there are 2 different starting indices i = 3 and i = 4, where we can reach the end with some number of
-jumps.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,3,1,1,4]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-From starting index i = 0, we make jumps to i = 1, i = 2, i = 3:
-During our 1st jump (odd-numbered), we first jump to i = 1 because arr[1] is the smallest value in [arr[1], arr[2], arr[3], arr[4]] that is greater than or equal to arr[0].
-During our 2nd jump (even-numbered), we jump from i = 1 to i = 2 because arr[2] is the largest value in [arr[2], arr[3], arr[4]] that is less than or equal to arr[1]. arr[3] is also the largest value, but 2 is a smaller index, so we can only jump to i = 2 and not i = 3
-During our 3rd jump (odd-numbered), we jump from i = 2 to i = 3 because arr[3] is the smallest value in [arr[3], arr[4]] that is greater than or equal to arr[2].
-We can&#39;t jump from i = 3 to i = 4, so the starting index i = 0 is not good.
-In a similar manner, we can deduce that:
-From starting index i = 1, we jump to i = 4, so we reach the end.
-From starting index i = 2, we jump to i = 3, and then we can&#39;t jump anymore.
-From starting index i = 3, we jump to i = 4, so we reach the end.
-From starting index i = 4, we are already at the end.
-In total, there are 3 different starting indices i = 1, i = 3, and i = 4, where we can reach the end with some
-number of jumps.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [5,1,3,4,2]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We can reach the end from starting indices 1, 2, and 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= arr[i] &lt; 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
diff --git a/problems/odd-even-jump/odd_even_jump.go b/problems/odd-even-jump/odd_even_jump.go
deleted file mode 100644
index 9f9b112b2..000000000
--- a/problems/odd-even-jump/odd_even_jump.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem975
diff --git a/problems/odd-even-linked-list/README.md b/problems/odd-even-linked-list/README.md
deleted file mode 100644
index febedeac1..000000000
--- a/problems/odd-even-linked-list/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-of-range-sum "Count of Range Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-increasing-path-in-a-matrix "Longest Increasing Path in a Matrix")
-
-## [328. Odd Even Linked List (Medium)](https://leetcode.com/problems/odd-even-linked-list "奇偶链表")
-
-<p>Given the <code>head</code> of a singly linked list, group all the nodes with odd indices together followed by the nodes with even indices, and return <em>the reordered list</em>.</p>
-
-<p>The <strong>first</strong> node is considered <strong>odd</strong>, and the <strong>second</strong> node is <strong>even</strong>, and so on.</p>
-
-<p>Note that the relative order inside both the even and odd groups should remain as it was in the input.</p>
-
-<p>You must solve the problem&nbsp;in <code>O(1)</code>&nbsp;extra space complexity and <code>O(n)</code> time complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/10/oddeven-linked-list.jpg" style="width: 300px; height: 123px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5]
-<strong>Output:</strong> [1,3,5,2,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/10/oddeven2-linked-list.jpg" style="width: 500px; height: 142px;" />
-<pre>
-<strong>Input:</strong> head = [2,1,3,5,6,4,7]
-<strong>Output:</strong> [2,3,6,7,1,5,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n ==&nbsp;</code>number of nodes in the linked list</li>
-	<li><code>0 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>6</sup> &lt;= Node.val &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Split Linked List in Parts](../split-linked-list-in-parts) (Medium)
diff --git a/problems/odd-even-linked-list/odd_even_linked_list.go b/problems/odd-even-linked-list/odd_even_linked_list.go
deleted file mode 100644
index f55a57f95..000000000
--- a/problems/odd-even-linked-list/odd_even_linked_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem328
diff --git a/problems/odd-even-linked-list/odd_even_linked_list_test.go b/problems/odd-even-linked-list/odd_even_linked_list_test.go
deleted file mode 100644
index f55a57f95..000000000
--- a/problems/odd-even-linked-list/odd_even_linked_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem328
diff --git a/problems/one-edit-distance/README.md b/problems/one-edit-distance/README.md
deleted file mode 100644
index abc01c622..000000000
--- a/problems/one-edit-distance/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../intersection-of-two-linked-lists "Intersection of Two Linked Lists")
-　　　　　　　　　　　　　　　　
-[Next >](../find-peak-element "Find Peak Element")
-
-## [161. One Edit Distance (Medium)](https://leetcode.com/problems/one-edit-distance "相隔为 1 的编辑距离")
-
-<p>Given two strings <b><i>s</i></b>&nbsp;and <b><i>t</i></b>, determine if they are both one edit distance apart.</p>
-
-<p><strong>Note:</strong>&nbsp;</p>
-
-<p>There are 3 possiblities to satisify one edit distance apart:</p>
-
-<ol>
-	<li>Insert a&nbsp;character into <strong><em>s</em></strong>&nbsp;to get&nbsp;<strong><em>t</em></strong></li>
-	<li>Delete a&nbsp;character from&nbsp;<strong><em>s</em></strong>&nbsp;to get&nbsp;<strong><em>t</em></strong></li>
-	<li>Replace a character of&nbsp;<strong><em>s</em></strong>&nbsp;to get&nbsp;<strong><em>t</em></strong></li>
-</ol>
-
-<p><strong>Example 1:</strong></p>
-
-<pre><strong>Input:</strong> <strong><em>s</em></strong> = &quot;ab&quot;, <strong><em>t</em></strong> = &quot;acb&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We can insert &#39;c&#39; into <strong><em>s</em></strong>&nbsp;to get&nbsp;<strong><em>t.</em></strong>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre><strong>Input:</strong> <strong><em>s</em></strong> = &quot;cab&quot;, <strong><em>t</em></strong> = &quot;ad&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> We cannot get <strong><em>t </em></strong>from <strong><em>s </em></strong>by only one step.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre><strong>Input:</strong> <strong><em>s</em></strong> = &quot;1203&quot;, <strong><em>t</em></strong> = &quot;1213&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We can replace &#39;0&#39; with &#39;1&#39; to get&nbsp;<strong><em>t.</em></strong></pre>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Edit Distance](../edit-distance) (Hard)
diff --git a/problems/one-edit-distance/one_edit_distance.go b/problems/one-edit-distance/one_edit_distance.go
deleted file mode 100644
index 45389ec03..000000000
--- a/problems/one-edit-distance/one_edit_distance.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem161
diff --git a/problems/one-edit-distance/one_edit_distance_test.go b/problems/one-edit-distance/one_edit_distance_test.go
deleted file mode 100644
index 45389ec03..000000000
--- a/problems/one-edit-distance/one_edit_distance_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem161
diff --git a/problems/ones-and-zeroes/README.md b/problems/ones-and-zeroes/README.md
deleted file mode 100644
index 04e698b54..000000000
--- a/problems/ones-and-zeroes/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../matchsticks-to-square "Matchsticks to Square")
-　　　　　　　　　　　　　　　　
-[Next >](../heaters "Heaters")
-
-## [474. Ones and Zeroes (Medium)](https://leetcode.com/problems/ones-and-zeroes "一和零")
-
-<p>You are given an array of binary strings <code>strs</code> and two integers <code>m</code> and <code>n</code>.</p>
-
-<p>Return <em>the size of the largest subset of <code>strs</code> such that there are <strong>at most</strong> </em><code>m</code><em> </em><code>0</code><em>&#39;s and </em><code>n</code><em> </em><code>1</code><em>&#39;s in the subset</em>.</p>
-
-<p>A set <code>x</code> is a <strong>subset</strong> of a set <code>y</code> if all elements of <code>x</code> are also elements of <code>y</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;10&quot;,&quot;0001&quot;,&quot;111001&quot;,&quot;1&quot;,&quot;0&quot;], m = 5, n = 3
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The largest subset with at most 5 0&#39;s and 3 1&#39;s is {&quot;10&quot;, &quot;0001&quot;, &quot;1&quot;, &quot;0&quot;}, so the answer is 4.
-Other valid but smaller subsets include {&quot;0001&quot;, &quot;1&quot;} and {&quot;10&quot;, &quot;1&quot;, &quot;0&quot;}.
-{&quot;111001&quot;} is an invalid subset because it contains 4 1&#39;s, greater than the maximum of 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;10&quot;,&quot;0&quot;,&quot;1&quot;], m = 1, n = 1
-<strong>Output:</strong> 2
-<b>Explanation:</b> The largest subset is {&quot;0&quot;, &quot;1&quot;}, so the answer is 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= strs.length &lt;= 600</code></li>
-	<li><code>1 &lt;= strs[i].length &lt;= 100</code></li>
-	<li><code>strs[i]</code> consists only of digits <code>&#39;0&#39;</code> and <code>&#39;1&#39;</code>.</li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Non-negative Integers without Consecutive Ones](../non-negative-integers-without-consecutive-ones) (Hard)
diff --git a/problems/ones-and-zeroes/ones_and_zeroes.go b/problems/ones-and-zeroes/ones_and_zeroes.go
deleted file mode 100644
index f06886db0..000000000
--- a/problems/ones-and-zeroes/ones_and_zeroes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem474
diff --git a/problems/ones-and-zeroes/ones_and_zeroes_test.go b/problems/ones-and-zeroes/ones_and_zeroes_test.go
deleted file mode 100644
index f06886db0..000000000
--- a/problems/ones-and-zeroes/ones_and_zeroes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem474
diff --git a/problems/online-election/README.md b/problems/online-election/README.md
deleted file mode 100644
index aca0c3936..000000000
--- a/problems/online-election/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-range-ii "Smallest Range II")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-an-array "Sort an Array")
-
-## [911. Online Election (Medium)](https://leetcode.com/problems/online-election "在线选举")
-
-<p>You are given two integer arrays <code>persons</code> and <code>times</code>. In an election, the <code>i<sup>th</sup></code> vote was cast for <code>persons[i]</code> at time <code>times[i]</code>.</p>
-
-<p>For each query at a time <code>t</code>, find the person that was leading the election at time <code>t</code>. Votes cast at time <code>t</code> will count towards our query. In the case of a tie, the most recent vote (among tied candidates) wins.</p>
-
-<p>Implement the <code>TopVotedCandidate</code> class:</p>
-
-<ul>
-	<li><code>TopVotedCandidate(int[] persons, int[] times)</code> Initializes the object with the <code>persons</code> and <code>times</code> arrays.</li>
-	<li><code>int q(int t)</code> Returns the number of the person that was leading the election at time <code>t</code> according to the mentioned rules.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;TopVotedCandidate&quot;, &quot;q&quot;, &quot;q&quot;, &quot;q&quot;, &quot;q&quot;, &quot;q&quot;, &quot;q&quot;]
-[[[0, 1, 1, 0, 0, 1, 0], [0, 5, 10, 15, 20, 25, 30]], [3], [12], [25], [15], [24], [8]]
-<strong>Output</strong>
-[null, 0, 1, 1, 0, 0, 1]
-
-<strong>Explanation</strong>
-TopVotedCandidate topVotedCandidate = new TopVotedCandidate([0, 1, 1, 0, 0, 1, 0], [0, 5, 10, 15, 20, 25, 30]);
-topVotedCandidate.q(3); // return 0, At time 3, the votes are [0], and 0 is leading.
-topVotedCandidate.q(12); // return 1, At time 12, the votes are [0,1,1], and 1 is leading.
-topVotedCandidate.q(25); // return 1, At time 25, the votes are [0,1,1,0,0,1], and 1 is leading (as ties go to the most recent vote.)
-topVotedCandidate.q(15); // return 0
-topVotedCandidate.q(24); // return 0
-topVotedCandidate.q(8); // return 1
-
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= persons.length &lt;= 5000</code></li>
-	<li><code>times.length == persons.length</code></li>
-	<li><code>0 &lt;= persons[i] &lt; persons.length</code></li>
-	<li><code>0 &lt;= times[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>times</code> is sorted in a strictly increasing order.</li>
-	<li><code>times[0] &lt;= t &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>q</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
diff --git a/problems/online-election/online_election.go b/problems/online-election/online_election.go
deleted file mode 100644
index 2133df127..000000000
--- a/problems/online-election/online_election.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem911
diff --git a/problems/online-election/online_election_test.go b/problems/online-election/online_election_test.go
deleted file mode 100644
index 2133df127..000000000
--- a/problems/online-election/online_election_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem911
diff --git a/problems/online-majority-element-in-subarray/README.md b/problems/online-majority-element-in-subarray/README.md
deleted file mode 100644
index a21a6a7ed..000000000
--- a/problems/online-majority-element-in-subarray/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../swap-for-longest-repeated-character-substring "Swap For Longest Repeated Character Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../market-analysis-i "Market Analysis I")
-
-## [1157. Online Majority Element In Subarray (Hard)](https://leetcode.com/problems/online-majority-element-in-subarray "子数组中占绝大多数的元素")
-
-<p>Design a data structure that efficiently finds the <strong>majority element</strong> of a given subarray.</p>
-
-<p>The <strong>majority element</strong> of a subarray is an element that occurs <code>threshold</code> times or more in the subarray.</p>
-
-<p>Implementing the <code>MajorityChecker</code> class:</p>
-
-<ul>
-	<li><code>MajorityChecker(int[] arr)</code> Initializes the instance of the class with the given array <code>arr</code>.</li>
-	<li><code>int query(int left, int right, int threshold)</code> returns the element in the subarray <code>arr[left...right]</code> that occurs at least <code>threshold</code> times, or <code>-1</code> if no such element exists.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;MajorityChecker&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;]
-[[[1, 1, 2, 2, 1, 1]], [0, 5, 4], [0, 3, 3], [2, 3, 2]]
-<strong>Output</strong>
-[null, 1, -1, 2]
-
-<strong>Explanation</strong>
-MajorityChecker majorityChecker = new MajorityChecker([1, 1, 2, 2, 1, 1]);
-majorityChecker.query(0, 5, 4); // return 1
-majorityChecker.query(0, 3, 3); // return -1
-majorityChecker.query(2, 3, 2); // return 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= left &lt;= right &lt; arr.length</code></li>
-	<li><code>threshold &lt;= right - left + 1</code></li>
-	<li><code>2 * threshold &gt; right - left + 1</code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>query</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What's special about a majority element ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-A majority element appears more than half the length of the array number of times.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If we tried a random index of the array, what's the probability that this index has a majority element ?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-It's more than 50% if that array has a majority element.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Try a random index for a proper number of times so that the probability of not finding the answer tends to zero.
-</details>
diff --git a/problems/online-stock-span/README.md b/problems/online-stock-span/README.md
deleted file mode 100644
index 169db46d1..000000000
--- a/problems/online-stock-span/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rle-iterator "RLE Iterator")
-　　　　　　　　　　　　　　　　
-[Next >](../numbers-at-most-n-given-digit-set "Numbers At Most N Given Digit Set")
-
-## [901. Online Stock Span (Medium)](https://leetcode.com/problems/online-stock-span "股票价格跨度")
-
-<p>Design an algorithm that collects daily price quotes for some stock and returns <strong>the span</strong> of that stock&#39;s price for the current day.</p>
-
-<p>The <strong>span</strong> of the stock&#39;s price today is defined as the maximum number of consecutive days (starting from today and going backward) for which the stock price was less than or equal to today&#39;s price.</p>
-
-<ul>
-	<li>For example, if the price of a stock over the next <code>7</code> days were <code>[100,80,60,70,60,75,85]</code>, then the stock spans would be <code>[1,1,1,2,1,4,6]</code>.</li>
-</ul>
-
-<p>Implement the <code>StockSpanner</code> class:</p>
-
-<ul>
-	<li><code>StockSpanner()</code> Initializes the object of the class.</li>
-	<li><code>int next(int price)</code> Returns the <strong>span</strong> of the stock&#39;s price given that today&#39;s price is <code>price</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;StockSpanner&quot;, &quot;next&quot;, &quot;next&quot;, &quot;next&quot;, &quot;next&quot;, &quot;next&quot;, &quot;next&quot;, &quot;next&quot;]
-[[], [100], [80], [60], [70], [60], [75], [85]]
-<strong>Output</strong>
-[null, 1, 1, 1, 2, 1, 4, 6]
-
-<strong>Explanation</strong>
-StockSpanner stockSpanner = new StockSpanner();
-stockSpanner.next(100); // return 1
-stockSpanner.next(80);  // return 1
-stockSpanner.next(60);  // return 1
-stockSpanner.next(70);  // return 2
-stockSpanner.next(60);  // return 1
-stockSpanner.next(75);  // return 4, because the last 4 prices (including today&#39;s price of 75) were less than or equal to today&#39;s price.
-stockSpanner.next(85);  // return 6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= price &lt;= 10<sup>5</sup></code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>next</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
diff --git a/problems/online-stock-span/online_stock_span.go b/problems/online-stock-span/online_stock_span.go
deleted file mode 100644
index c8edce2ce..000000000
--- a/problems/online-stock-span/online_stock_span.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem901
diff --git a/problems/online-stock-span/online_stock_span_test.go b/problems/online-stock-span/online_stock_span_test.go
deleted file mode 100644
index c8edce2ce..000000000
--- a/problems/online-stock-span/online_stock_span_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem901
diff --git a/problems/open-the-lock/README.md b/problems/open-the-lock/README.md
deleted file mode 100644
index ea5d76e20..000000000
--- a/problems/open-the-lock/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ip-to-cidr "IP to CIDR")
-　　　　　　　　　　　　　　　　
-[Next >](../cracking-the-safe "Cracking the Safe")
-
-## [752. Open the Lock (Medium)](https://leetcode.com/problems/open-the-lock "打开转盘锁")
-
-<p>You have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: <code>&#39;0&#39;, &#39;1&#39;, &#39;2&#39;, &#39;3&#39;, &#39;4&#39;, &#39;5&#39;, &#39;6&#39;, &#39;7&#39;, &#39;8&#39;, &#39;9&#39;</code>. The wheels can rotate freely and wrap around: for example we can turn <code>&#39;9&#39;</code> to be <code>&#39;0&#39;</code>, or <code>&#39;0&#39;</code> to be <code>&#39;9&#39;</code>. Each move consists of turning one wheel one slot.</p>
-
-<p>The lock initially starts at <code>&#39;0000&#39;</code>, a string representing the state of the 4 wheels.</p>
-
-<p>You are given a list of <code>deadends</code> dead ends, meaning if the lock displays any of these codes, the wheels of the lock will stop turning and you will be unable to open it.</p>
-
-<p>Given a <code>target</code> representing the value of the wheels that will unlock the lock, return the minimum total number of turns required to open the lock, or -1 if it is impossible.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> deadends = [&quot;0201&quot;,&quot;0101&quot;,&quot;0102&quot;,&quot;1212&quot;,&quot;2002&quot;], target = &quot;0202&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong>
-A sequence of valid moves would be &quot;0000&quot; -&gt; &quot;1000&quot; -&gt; &quot;1100&quot; -&gt; &quot;1200&quot; -&gt; &quot;1201&quot; -&gt; &quot;1202&quot; -&gt; &quot;0202&quot;.
-Note that a sequence like &quot;0000&quot; -&gt; &quot;0001&quot; -&gt; &quot;0002&quot; -&gt; &quot;0102&quot; -&gt; &quot;0202&quot; would be invalid,
-because the wheels of the lock become stuck after the display becomes the dead end &quot;0102&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> deadends = [&quot;8888&quot;], target = &quot;0009&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-We can turn the last wheel in reverse to move from &quot;0000&quot; -&gt; &quot;0009&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> deadends = [&quot;8887&quot;,&quot;8889&quot;,&quot;8878&quot;,&quot;8898&quot;,&quot;8788&quot;,&quot;8988&quot;,&quot;7888&quot;,&quot;9888&quot;], target = &quot;8888&quot;
-<strong>Output:</strong> -1
-Explanation:
-We can&#39;t reach the target without getting stuck.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> deadends = [&quot;0000&quot;], target = &quot;8888&quot;
-<strong>Output:</strong> -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;deadends.length &lt;= 500</code></li>
-	<li><code><font face="monospace">deadends[i].length == 4</font></code></li>
-	<li><code><font face="monospace">target.length == 4</font></code></li>
-	<li>target <strong>will not be</strong> in the list <code>deadends</code>.</li>
-	<li><code>target</code> and <code>deadends[i]</code> consist of digits only.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can think of this problem as a shortest path problem on a graph: there are `10000` nodes (strings `'0000'` to `'9999'`), and there is an edge between two nodes if they differ in one digit, that digit differs by 1 (wrapping around, so `'0'` and `'9'` differ by 1), and if *both* nodes are not in `deadends`.
-</details>
diff --git a/problems/open-the-lock/open_the_lock.go b/problems/open-the-lock/open_the_lock.go
deleted file mode 100644
index 2b5cf3464..000000000
--- a/problems/open-the-lock/open_the_lock.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem752
diff --git a/problems/open-the-lock/open_the_lock_test.go b/problems/open-the-lock/open_the_lock_test.go
deleted file mode 100644
index 2b5cf3464..000000000
--- a/problems/open-the-lock/open_the_lock_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem752
diff --git a/problems/operations-on-tree/README.md b/problems/operations-on-tree/README.md
deleted file mode 100644
index e249614a9..000000000
--- a/problems/operations-on-tree/README.md
+++ /dev/null
@@ -1,92 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-all-groups-of-farmland "Find All Groups of Farmland")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-good-subsets "The Number of Good Subsets")
-
-## [1993. Operations on Tree (Medium)](https://leetcode.com/problems/operations-on-tree "树上的操作")
-
-<p>You are given a tree with <code>n</code> nodes numbered from <code>0</code> to <code>n - 1</code> in the form of a parent array <code>parent</code> where <code>parent[i]</code> is the parent of the <code>i<sup>th</sup></code> node. The root of the tree is node <code>0</code>, so <code>parent[0] = -1</code> since it has no parent. You want to design a data structure that allows users to lock, unlock, and upgrade nodes in the tree.</p>
-
-<p>The data structure should support the following functions:</p>
-
-<ul>
-	<li><strong>Lock:</strong> <strong>Locks</strong> the given node for the given user and prevents other users from locking the same node. You may only lock a node using this function if the node is unlocked.</li>
-	<li><strong>Unlock: Unlocks</strong> the given node for the given user. You may only unlock a node using this function if it is currently locked by the same user.</li>
-	<li><b>Upgrade</b><strong>: Locks</strong> the given node for the given user and <strong>unlocks</strong> all of its descendants <strong>regardless</strong> of who locked it. You may only upgrade a node if <strong>all</strong> 3 conditions are true:
-	<ul>
-		<li>The node is unlocked,</li>
-		<li>It has at least one locked descendant (by <strong>any</strong> user), and</li>
-		<li>It does not have any locked ancestors.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Implement the <code>LockingTree</code> class:</p>
-
-<ul>
-	<li><code>LockingTree(int[] parent)</code> initializes the data structure with the parent array.</li>
-	<li><code>lock(int num, int user)</code> returns <code>true</code> if it is possible for the user with id <code>user</code> to lock the node <code>num</code>, or <code>false</code> otherwise. If it is possible, the node <code>num</code> will become<strong> locked</strong> by the user with id <code>user</code>.</li>
-	<li><code>unlock(int num, int user)</code> returns <code>true</code> if it is possible for the user with id <code>user</code> to unlock the node <code>num</code>, or <code>false</code> otherwise. If it is possible, the node <code>num</code> will become <strong>unlocked</strong>.</li>
-	<li><code>upgrade(int num, int user)</code> returns <code>true</code> if it is possible for the user with id <code>user</code> to upgrade the node <code>num</code>, or <code>false</code> otherwise. If it is possible, the node <code>num</code> will be <strong>upgraded</strong>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/29/untitled.png" style="width: 375px; height: 246px;" />
-<pre>
-<strong>Input</strong>
-[&quot;LockingTree&quot;, &quot;lock&quot;, &quot;unlock&quot;, &quot;unlock&quot;, &quot;lock&quot;, &quot;upgrade&quot;, &quot;lock&quot;]
-[[[-1, 0, 0, 1, 1, 2, 2]], [2, 2], [2, 3], [2, 2], [4, 5], [0, 1], [0, 1]]
-<strong>Output</strong>
-[null, true, false, true, true, true, false]
-
-<strong>Explanation</strong>
-LockingTree lockingTree = new LockingTree([-1, 0, 0, 1, 1, 2, 2]);
-lockingTree.lock(2, 2);    // return true because node 2 is unlocked.
-                           // Node 2 will now be locked by user 2.
-lockingTree.unlock(2, 3);  // return false because user 3 cannot unlock a node locked by user 2.
-lockingTree.unlock(2, 2);  // return true because node 2 was previously locked by user 2.
-                           // Node 2 will now be unlocked.
-lockingTree.lock(4, 5);    // return true because node 4 is unlocked.
-                           // Node 4 will now be locked by user 5.
-lockingTree.upgrade(0, 1); // return true because node 0 is unlocked and has at least one locked descendant (node 4).
-                           // Node 0 will now be locked by user 1 and node 4 will now be unlocked.
-lockingTree.lock(0, 1);    // return false because node 0 is already locked.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == parent.length</code></li>
-	<li><code>2 &lt;= n &lt;= 2000</code></li>
-	<li><code>0 &lt;= parent[i] &lt;= n - 1</code> for <code>i != 0</code></li>
-	<li><code>parent[0] == -1</code></li>
-	<li><code>0 &lt;= num &lt;= n - 1</code></li>
-	<li><code>1 &lt;= user &lt;= 10<sup>4</sup></code></li>
-	<li><code>parent</code> represents a valid tree.</li>
-	<li>At most <code>2000</code> calls <strong>in total</strong> will be made to <code>lock</code>, <code>unlock</code>, and <code>upgrade</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can we use the small constraints to help us solve the problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we traverse the ancestors and descendants of a node?
-</details>
diff --git a/problems/optimal-account-balancing/README.md b/problems/optimal-account-balancing/README.md
deleted file mode 100644
index 0a74001fe..000000000
--- a/problems/optimal-account-balancing/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../can-i-win "Can I Win")
-　　　　　　　　　　　　　　　　
-[Next >](../count-the-repetitions "Count The Repetitions")
-
-## [465. Optimal Account Balancing (Hard)](https://leetcode.com/problems/optimal-account-balancing "最优账单平衡")
-
-<p>A group of friends went on holiday and sometimes lent each other money. For example, Alice paid for Bill's lunch for $10. Then later Chris gave Alice $5 for a taxi ride. We can model each transaction as a tuple (x, y, z) which means person x gave person y $z. Assuming Alice, Bill, and Chris are person 0, 1, and 2 respectively (0, 1, 2 are the person's ID), the transactions can be represented as <code>[[0, 1, 10], [2, 0, 5]]</code>.</p>
-
-<p>Given a list of transactions between a group of people, return the minimum number of transactions required to settle the debt.</p>
-
-<p><b>Note:</b>
-<ol>
-<li>A transaction will be given as a tuple (x, y, z). Note that <code>x &ne; y</code> and <code>z > 0</code>.</li>
-<li>Person's IDs may not be linear, e.g. we could have the persons 0, 1, 2 or we could also have the persons 0, 2, 6.</li>
-</ol>
-</p>
-
-<p><b>Example 1:</b>
-<pre>
-<b>Input:</b>
-[[0,1,10], [2,0,5]]
-
-<b>Output:</b>
-2
-
-<b>Explanation:</b>
-Person #0 gave person #1 $10.
-Person #2 gave person #0 $5.
-
-Two transactions are needed. One way to settle the debt is person #1 pays person #0 and #2 $5 each.
-</pre>
-</p>
-
-<p><b>Example 2:</b>
-<pre>
-<b>Input:</b>
-[[0,1,10], [1,0,1], [1,2,5], [2,0,5]]
-
-<b>Output:</b>
-1
-
-<b>Explanation:</b>
-Person #0 gave person #1 $10.
-Person #1 gave person #0 $1.
-Person #1 gave person #2 $5.
-Person #2 gave person #0 $5.
-
-Therefore, person #1 only need to give person #0 $4, and all debt is settled.
-</pre>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
diff --git a/problems/optimal-account-balancing/optimal_account_balancing.go b/problems/optimal-account-balancing/optimal_account_balancing.go
deleted file mode 100644
index 9ad538509..000000000
--- a/problems/optimal-account-balancing/optimal_account_balancing.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem465
diff --git a/problems/optimal-account-balancing/optimal_account_balancing_test.go b/problems/optimal-account-balancing/optimal_account_balancing_test.go
deleted file mode 100644
index 9ad538509..000000000
--- a/problems/optimal-account-balancing/optimal_account_balancing_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem465
diff --git a/problems/optimal-division/README.md b/problems/optimal-division/README.md
deleted file mode 100644
index b24028aef..000000000
--- a/problems/optimal-division/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../student-attendance-record-ii "Student Attendance Record II")
-　　　　　　　　　　　　　　　　
-[Next >](../brick-wall "Brick Wall")
-
-## [553. Optimal Division (Medium)](https://leetcode.com/problems/optimal-division "最优除法")
-
-<p>You are given an integer array <code>nums</code>. The adjacent integers in <code>nums</code> will perform the float division.</p>
-
-<ul>
-	<li>For example, for <code>nums = [2,3,4]</code>, we will evaluate the expression <code>&quot;2/3/4&quot;</code>.</li>
-</ul>
-
-<p>However, you can add any number of parenthesis at any position to change the priority of operations. You want to add these parentheses such the value of the expression after the evaluation is maximum.</p>
-
-<p>Return <em>the corresponding expression that has the maximum value in string format</em>.</p>
-
-<p><strong>Note:</strong> your expression should not contain redundant parenthesis.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1000,100,10,2]
-<strong>Output:</strong> &quot;1000/(100/10/2)&quot;
-<strong>Explanation:</strong>
-1000/(100/10/2) = 1000/((100/10)/2) = 200
-However, the bold parenthesis in &quot;1000/((100/10)/2)&quot; are redundant, since they don&#39;t influence the operation priority. So you should return &quot;1000/(100/10/2)&quot;.
-Other cases:
-1000/(100/10)/2 = 50
-1000/(100/(10/2)) = 50
-1000/100/10/2 = 0.5
-1000/100/(10/2) = 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,4]
-<strong>Output:</strong> &quot;2/(3/4)&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2]
-<strong>Output:</strong> &quot;2&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10</code></li>
-	<li><code>2 &lt;= nums[i] &lt;= 1000</code></li>
-	<li>There is only one optimal division for the given iput.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/optimal-division/optimal_division.go b/problems/optimal-division/optimal_division.go
deleted file mode 100644
index d1f6d0045..000000000
--- a/problems/optimal-division/optimal_division.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem553
diff --git a/problems/optimal-division/optimal_division_test.go b/problems/optimal-division/optimal_division_test.go
deleted file mode 100644
index d1f6d0045..000000000
--- a/problems/optimal-division/optimal_division_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem553
diff --git a/problems/optimize-water-distribution-in-a-village/README.md b/problems/optimize-water-distribution-in-a-village/README.md
deleted file mode 100644
index 29b3a78bd..000000000
--- a/problems/optimize-water-distribution-in-a-village/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-connect-sticks "Minimum Cost to Connect Sticks")
-　　　　　　　　　　　　　　　　
-[Next >](../invalid-transactions "Invalid Transactions")
-
-## [1168. Optimize Water Distribution in a Village (Hard)](https://leetcode.com/problems/optimize-water-distribution-in-a-village "水资源分配优化")
-
-<p>There are <code><font face="monospace">n</font></code>&nbsp;houses in a village. We want to supply water for all the houses by building wells and laying pipes.</p>
-
-<p>For each house <code>i</code>, we can either build a well inside it directly with cost <code>wells[i]</code>, or pipe in water from another well to it. The costs to lay pipes between houses are given by the array <code>pipes</code>, where each&nbsp;<code>pipes[i] = [house1, house2, cost]</code>&nbsp;represents the cost to connect&nbsp;<code>house1</code>&nbsp;and <code>house2</code>&nbsp;together using a pipe.&nbsp;Connections are bidirectional.</p>
-
-<p>Find the minimum total cost to supply water to all houses.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/05/22/1359_ex1.png" style="width: 189px; height: 196px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, wells = [1,2,2], pipes = [[1,2,1],[2,3,1]]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>
-The image shows the costs of connecting houses using pipes.
-The best strategy is to build a well in the first house with cost 1 and connect the other houses to it with cost 2 so the total cost is 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n&nbsp;&lt;= 10000</code></li>
-	<li><code>wells.length == n</code></li>
-	<li><code>0 &lt;= wells[i] &lt;= 10^5</code></li>
-	<li><code>1 &lt;= pipes.length &lt;= 10000</code></li>
-	<li><code>1 &lt;= pipes[i][0], pipes[i][1] &lt;= n</code></li>
-	<li><code>0 &lt;= pipes[i][2] &lt;= 10^5</code></li>
-	<li><code>pipes[i][0] != pipes[i][1]</code></li>
-</ul>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Minimum Spanning Tree](../../tag/minimum-spanning-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if we model this problem as a graph problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-A house is a node and a pipe is a weighted edge.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How to represent building wells in the graph model?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Add a virtual node, connect it to houses with edges weighted by the costs to build wells in these houses.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-The problem is now reduced to a Minimum Spanning Tree problem.
-</details>
diff --git a/problems/order-two-columns-independently/README.md b/problems/order-two-columns-independently/README.md
deleted file mode 100644
index 24bed0989..000000000
--- a/problems/order-two-columns-independently/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../amount-of-new-area-painted-each-day "Amount of New Area Painted Each Day")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-sum-of-four-digit-number-after-splitting-digits "Minimum Sum of Four Digit Number After Splitting Digits")
-
-## [2159. Order Two Columns Independently (Medium)](https://leetcode.com/problems/order-two-columns-independently "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/order-two-columns-independently/mysql_schemas.sql b/problems/order-two-columns-independently/mysql_schemas.sql
deleted file mode 100644
index 444d9231f..000000000
--- a/problems/order-two-columns-independently/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Data (first_col int, second_col int);
-Truncate table Data;
-insert into Data (first_col, second_col) values ('4', '2');
-insert into Data (first_col, second_col) values ('2', '3');
-insert into Data (first_col, second_col) values ('3', '1');
-insert into Data (first_col, second_col) values ('1', '4');
diff --git a/problems/orderly-queue/README.md b/problems/orderly-queue/README.md
deleted file mode 100644
index 057a44d4e..000000000
--- a/problems/orderly-queue/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bitwise-ors-of-subarrays "Bitwise ORs of Subarrays")
-　　　　　　　　　　　　　　　　
-[Next >](../rle-iterator "RLE Iterator")
-
-## [899. Orderly Queue (Hard)](https://leetcode.com/problems/orderly-queue "有序队列")
-
-<p>You are given a string <code>s</code> and an integer <code>k</code>. You can choose one of the first <code>k</code> letters of <code>s</code> and append it at the end of the string..</p>
-
-<p>Return <em>the lexicographically smallest string you could have after applying the mentioned step any number of moves</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cba&quot;, k = 1
-<strong>Output:</strong> &quot;acb&quot;
-<strong>Explanation:</strong> 
-In the first move, we move the 1<sup>st</sup> character &#39;c&#39; to the end, obtaining the string &quot;bac&quot;.
-In the second move, we move the 1<sup>st</sup> character &#39;b&#39; to the end, obtaining the final result &quot;acb&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;baaca&quot;, k = 3
-<strong>Output:</strong> &quot;aaabc&quot;
-<strong>Explanation:</strong> 
-In the first move, we move the 1<sup>st</sup> character &#39;b&#39; to the end, obtaining the string &quot;aacab&quot;.
-In the second move, we move the 3<sup>rd</sup> character &#39;c&#39; to the end, obtaining the final result &quot;aaabc&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/orderly-queue/orderly_queue.go b/problems/orderly-queue/orderly_queue.go
deleted file mode 100644
index ba20e1e20..000000000
--- a/problems/orderly-queue/orderly_queue.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem899
diff --git a/problems/orderly-queue/orderly_queue_test.go b/problems/orderly-queue/orderly_queue_test.go
deleted file mode 100644
index ba20e1e20..000000000
--- a/problems/orderly-queue/orderly_queue_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem899
diff --git a/problems/orders-with-maximum-quantity-above-average/README.md b/problems/orders-with-maximum-quantity-above-average/README.md
deleted file mode 100644
index 4743751d8..000000000
--- a/problems/orders-with-maximum-quantity-above-average/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-rearrange-sticks-with-k-sticks-visible "Number of Ways to Rearrange Sticks With K Sticks Visible")
-　　　　　　　　　　　　　　　　
-[Next >](../product-of-two-run-length-encoded-arrays "Product of Two Run-Length Encoded Arrays")
-
-## [1867. Orders With Maximum Quantity Above Average (Medium)](https://leetcode.com/problems/orders-with-maximum-quantity-above-average "最大数量高于平均水平的订单")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/orders-with-maximum-quantity-above-average/mysql_schemas.sql b/problems/orders-with-maximum-quantity-above-average/mysql_schemas.sql
deleted file mode 100644
index 1e84558f9..000000000
--- a/problems/orders-with-maximum-quantity-above-average/mysql_schemas.sql
+++ /dev/null
@@ -1,16 +0,0 @@
-Create table If Not Exists OrdersDetails (order_id int, product_id int, quantity int);
-Truncate table OrdersDetails;
-insert into OrdersDetails (order_id, product_id, quantity) values ('1', '1', '12');
-insert into OrdersDetails (order_id, product_id, quantity) values ('1', '2', '10');
-insert into OrdersDetails (order_id, product_id, quantity) values ('1', '3', '15');
-insert into OrdersDetails (order_id, product_id, quantity) values ('2', '1', '8');
-insert into OrdersDetails (order_id, product_id, quantity) values ('2', '4', '4');
-insert into OrdersDetails (order_id, product_id, quantity) values ('2', '5', '6');
-insert into OrdersDetails (order_id, product_id, quantity) values ('3', '3', '5');
-insert into OrdersDetails (order_id, product_id, quantity) values ('3', '4', '18');
-insert into OrdersDetails (order_id, product_id, quantity) values ('4', '5', '2');
-insert into OrdersDetails (order_id, product_id, quantity) values ('4', '6', '8');
-insert into OrdersDetails (order_id, product_id, quantity) values ('5', '7', '9');
-insert into OrdersDetails (order_id, product_id, quantity) values ('5', '8', '9');
-insert into OrdersDetails (order_id, product_id, quantity) values ('3', '9', '20');
-insert into OrdersDetails (order_id, product_id, quantity) values ('2', '9', '4');
diff --git a/problems/out-of-boundary-paths/README.md b/problems/out-of-boundary-paths/README.md
deleted file mode 100644
index d870983f9..000000000
--- a/problems/out-of-boundary-paths/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distribute-candies "Distribute Candies")
-　　　　　　　　　　　　　　　　
-[Next >](../employee-bonus "Employee Bonus")
-
-## [576. Out of Boundary Paths (Medium)](https://leetcode.com/problems/out-of-boundary-paths "出界的路径数")
-
-<p>There is an <code>m x n</code> grid with a ball. The ball is initially at the position <code>[startRow, startColumn]</code>. You are allowed to move the ball to one of the four adjacent cells in the grid (possibly out of the grid crossing the grid boundary). You can apply <strong>at most</strong> <code>maxMove</code> moves to the ball.</p>
-
-<p>Given the five integers <code>m</code>, <code>n</code>, <code>maxMove</code>, <code>startRow</code>, <code>startColumn</code>, return the number of paths to move the ball out of the grid boundary. Since the answer can be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/28/out_of_boundary_paths_1.png" style="width: 500px; height: 296px;" />
-<pre>
-<strong>Input:</strong> m = 2, n = 2, maxMove = 2, startRow = 0, startColumn = 0
-<strong>Output:</strong> 6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/28/out_of_boundary_paths_2.png" style="width: 500px; height: 293px;" />
-<pre>
-<strong>Input:</strong> m = 1, n = 3, maxMove = 3, startRow = 0, startColumn = 1
-<strong>Output:</strong> 12
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>0 &lt;= maxMove &lt;= 50</code></li>
-	<li><code>0 &lt;= startRow &lt; m</code></li>
-	<li><code>0 &lt;= startColumn &lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Knight Probability in Chessboard](../knight-probability-in-chessboard) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is traversing every path feasible? There are many possible paths for a small matrix. Try to optimize it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use some space to store the number of paths and update them after every move?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-One obvious thing: the ball will go out of the boundary only by crossing it. Also, there is only one possible way the ball can go out of the boundary from the boundary cell except for corner cells. From the corner cell, the ball can go out in two different ways.
-
-Can you use this thing to solve the problem?
-</details>
diff --git a/problems/out-of-boundary-paths/out_of_boundary_paths.go b/problems/out-of-boundary-paths/out_of_boundary_paths.go
deleted file mode 100644
index 3a312b812..000000000
--- a/problems/out-of-boundary-paths/out_of_boundary_paths.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem576
diff --git a/problems/out-of-boundary-paths/out_of_boundary_paths_test.go b/problems/out-of-boundary-paths/out_of_boundary_paths_test.go
deleted file mode 100644
index 3a312b812..000000000
--- a/problems/out-of-boundary-paths/out_of_boundary_paths_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem576
diff --git a/problems/output-contest-matches/README.md b/problems/output-contest-matches/README.md
deleted file mode 100644
index d2ed16eb9..000000000
--- a/problems/output-contest-matches/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../diameter-of-binary-tree "Diameter of Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../boundary-of-binary-tree "Boundary of Binary Tree")
-
-## [544. Output Contest Matches (Medium)](https://leetcode.com/problems/output-contest-matches "输出比赛匹配对")
-
-<p>
-During the NBA playoffs, we always arrange the rather strong team to play with the rather weak team, like make the rank 1 team play with the rank n<sub>th</sub> team, which is a good strategy to make the contest more interesting. Now, you're given <b>n</b> teams, you need to output their <b>final</b> contest matches in the form of a string.
-</p>
-
-<p>The <b>n</b> teams are given in the form of positive integers from 1 to n, which represents their initial rank. (Rank 1 is the strongest team and Rank n is the weakest team.) We'll use parentheses('(', ')') and commas(',') to represent the contest team pairing - parentheses('(' , ')') for pairing and commas(',') for partition. During the pairing process in each round, you always need to follow the strategy of making the rather strong one pair with the rather weak one.</p> 
-
-<p><b>Example 1:</b><br />
-<pre><b>Input:</b> 2
-<b>Output:</b> (1,2)
-<b>Explanation:</b> 
-Initially, we have the team 1 and the team 2, placed like: 1,2.
-Then we pair the team (1,2) together with '(', ')' and ',', which is the final answer.
-</pre>
-</p>
-
-<p><b>Example 2:</b><br />
-<pre><b>Input:</b> 4
-<b>Output:</b> ((1,4),(2,3))
-<b>Explanation:</b> 
-In the first round, we pair the team 1 and 4, the team 2 and 3 together, as we need to make the strong team and weak team together.
-And we got (1,4),(2,3).
-In the second round, the winners of (1,4) and (2,3) need to play again to generate the final winner, so you need to add the paratheses outside them.
-And we got the final answer ((1,4),(2,3)).
-</pre>
-</p>
-
-<p><b>Example 3:</b><br />
-<pre><b>Input:</b> 8
-<b>Output:</b> (((1,8),(4,5)),((2,7),(3,6)))
-<b>Explanation:</b> 
-First round: (1,8),(2,7),(3,6),(4,5)
-Second round: ((1,8),(4,5)),((2,7),(3,6))
-Third round: (((1,8),(4,5)),((2,7),(3,6)))
-Since the third round will generate the final winner, you need to output the answer (((1,8),(4,5)),((2,7),(3,6))).
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>The <b>n</b> is in range [2, 2<sup>12</sup>].</li>
-<li>We ensure that the input <b>n</b> can be converted into the form 2<sup>k</sup>, where k is a positive integer.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/output-contest-matches/output_contest_matches.go b/problems/output-contest-matches/output_contest_matches.go
deleted file mode 100644
index 2950ef121..000000000
--- a/problems/output-contest-matches/output_contest_matches.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem544
diff --git a/problems/output-contest-matches/output_contest_matches_test.go b/problems/output-contest-matches/output_contest_matches_test.go
deleted file mode 100644
index 2950ef121..000000000
--- a/problems/output-contest-matches/output_contest_matches_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem544
diff --git a/problems/pacific-atlantic-water-flow/README.md b/problems/pacific-atlantic-water-flow/README.md
deleted file mode 100644
index 7e8c05bc0..000000000
--- a/problems/pacific-atlantic-water-flow/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partition-equal-subset-sum "Partition Equal Subset Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../sentence-screen-fitting "Sentence Screen Fitting")
-
-## [417. Pacific Atlantic Water Flow (Medium)](https://leetcode.com/problems/pacific-atlantic-water-flow "太平洋大西洋水流问题")
-
-<p>There is an <code>m x n</code> rectangular island that borders both the <strong>Pacific Ocean</strong> and <strong>Atlantic Ocean</strong>. The <strong>Pacific Ocean</strong> touches the island&#39;s left and top edges, and the <strong>Atlantic Ocean</strong> touches the island&#39;s right and bottom edges.</p>
-
-<p>The island is partitioned into a grid of square cells. You are given an <code>m x n</code> integer matrix <code>heights</code> where <code>heights[r][c]</code> represents the <strong>height above sea level</strong> of the cell at coordinate <code>(r, c)</code>.</p>
-
-<p>The island receives a lot of rain, and the rain water can flow to neighboring cells directly north, south, east, and west if the neighboring cell&#39;s height is <strong>less than or equal to</strong> the current cell&#39;s height. Water can flow from any cell adjacent to an ocean into the ocean.</p>
-
-<p>Return <em>a <strong>2D list</strong> of grid coordinates </em><code>result</code><em> where </em><code>result[i] = [r<sub>i</sub>, c<sub>i</sub>]</code><em> denotes that rain water can flow from cell </em><code>(r<sub>i</sub>, c<sub>i</sub>)</code><em> to <strong>both</strong> the Pacific and Atlantic oceans</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/08/waterflow-grid.jpg" style="width: 573px; height: 573px;" />
-<pre>
-<strong>Input:</strong> heights = [[1,2,2,3,5],[3,2,3,4,4],[2,4,5,3,1],[6,7,1,4,5],[5,1,1,2,4]]
-<strong>Output:</strong> [[0,4],[1,3],[1,4],[2,2],[3,0],[3,1],[4,0]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> heights = [[2,1],[1,2]]
-<strong>Output:</strong> [[0,0],[0,1],[1,0],[1,1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == heights.length</code></li>
-	<li><code>n == heights[r].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>0 &lt;= heights[r][c] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/pacific-atlantic-water-flow/pacific_atlantic_water_flow.go b/problems/pacific-atlantic-water-flow/pacific_atlantic_water_flow.go
deleted file mode 100644
index ca9868411..000000000
--- a/problems/pacific-atlantic-water-flow/pacific_atlantic_water_flow.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem417
diff --git a/problems/pacific-atlantic-water-flow/pacific_atlantic_water_flow_test.go b/problems/pacific-atlantic-water-flow/pacific_atlantic_water_flow_test.go
deleted file mode 100644
index ca9868411..000000000
--- a/problems/pacific-atlantic-water-flow/pacific_atlantic_water_flow_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem417
diff --git a/problems/page-recommendations-ii/README.md b/problems/page-recommendations-ii/README.md
deleted file mode 100644
index 3e21532ec..000000000
--- a/problems/page-recommendations-ii/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cutting-ribbons "Cutting Ribbons")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-all-the-integers-in-a-range-are-covered "Check if All the Integers in a Range Are Covered")
-
-## [1892. Page Recommendations II (Hard)](https://leetcode.com/problems/page-recommendations-ii "页面推荐Ⅱ")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/page-recommendations-ii/mysql_schemas.sql b/problems/page-recommendations-ii/mysql_schemas.sql
deleted file mode 100644
index d7b0e4af6..000000000
--- a/problems/page-recommendations-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,20 +0,0 @@
-Create table If Not Exists Friendship (user1_id int, user2_id int);
-Create table If Not Exists Likes (user_id int, page_id int);
-Truncate table Friendship;
-insert into Friendship (user1_id, user2_id) values ('1', '2');
-insert into Friendship (user1_id, user2_id) values ('1', '3');
-insert into Friendship (user1_id, user2_id) values ('1', '4');
-insert into Friendship (user1_id, user2_id) values ('2', '3');
-insert into Friendship (user1_id, user2_id) values ('2', '4');
-insert into Friendship (user1_id, user2_id) values ('2', '5');
-insert into Friendship (user1_id, user2_id) values ('6', '1');
-Truncate table Likes;
-insert into Likes (user_id, page_id) values ('1', '88');
-insert into Likes (user_id, page_id) values ('2', '23');
-insert into Likes (user_id, page_id) values ('3', '24');
-insert into Likes (user_id, page_id) values ('4', '56');
-insert into Likes (user_id, page_id) values ('5', '11');
-insert into Likes (user_id, page_id) values ('6', '33');
-insert into Likes (user_id, page_id) values ('2', '77');
-insert into Likes (user_id, page_id) values ('3', '77');
-insert into Likes (user_id, page_id) values ('6', '88');
diff --git a/problems/page-recommendations/README.md b/problems/page-recommendations/README.md
deleted file mode 100644
index 3faa1073c..000000000
--- a/problems/page-recommendations/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-moves-to-move-a-box-to-their-target-location "Minimum Moves to Move a Box to Their Target Location")
-　　　　　　　　　　　　　　　　
-[Next >](../print-immutable-linked-list-in-reverse "Print Immutable Linked List in Reverse")
-
-## [1264. Page Recommendations (Medium)](https://leetcode.com/problems/page-recommendations "页面推荐")
-
-<p>Table: <code>Friendship</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| user1_id      | int     |
-| user2_id      | int     |
-+---------------+---------+
-(user1_id, user2_id) is the primary key for this table.
-Each row of this table indicates that there is a friendship relation between user1_id and user2_id.
-</pre>
- 
-<p>Table: <code>Likes</code></p>
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| user_id     | int     |
-| page_id     | int     |
-+-------------+---------+
-(user_id, page_id) is the primary key for this table.
-Each row of this table indicates that user_id likes page_id.
-</pre>
- 
-Write an SQL query to recommend pages to the user with user_id = 1 using the pages that your friends liked. It should not recommend pages you already liked.
-
-Return result table in any order without duplicates.
-
-The query result format is in the following example:
-<pre>
-Friendship table:
-+----------+----------+
-| user1_id | user2_id |
-+----------+----------+
-| 1        | 2        |
-| 1        | 3        |
-| 1        | 4        |
-| 2        | 3        |
-| 2        | 4        |
-| 2        | 5        |
-| 6        | 1        |
-+----------+----------+
- 
-Likes table:
-+---------+---------+
-| user_id | page_id |
-+---------+---------+
-| 1       | 88      |
-| 2       | 23      |
-| 3       | 24      |
-| 4       | 56      |
-| 5       | 11      |
-| 6       | 33      |
-| 2       | 77      |
-| 3       | 77      |
-| 6       | 88      |
-+---------+---------+
-
-Result table:
-+------------------+
-| recommended_page |
-+------------------+
-| 23               |
-| 24               |
-| 56               |
-| 33               |
-| 77               |
-+------------------+
-User one is friend with users 2, 3, 4 and 6.
-Suggested pages are 23 from user 2, 24 from user 3, 56 from user 3 and 33 from user 6.
-Page 77 is suggested from both user 2 and user 3.
-Page 88 is not suggested because user 1 already likes it.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Page Recommendations II](../page-recommendations-ii) (Hard)
-  1. [Strong Friendship](../strong-friendship) (Medium)
diff --git a/problems/page-recommendations/mysql_schemas.sql b/problems/page-recommendations/mysql_schemas.sql
deleted file mode 100644
index d7b0e4af6..000000000
--- a/problems/page-recommendations/mysql_schemas.sql
+++ /dev/null
@@ -1,20 +0,0 @@
-Create table If Not Exists Friendship (user1_id int, user2_id int);
-Create table If Not Exists Likes (user_id int, page_id int);
-Truncate table Friendship;
-insert into Friendship (user1_id, user2_id) values ('1', '2');
-insert into Friendship (user1_id, user2_id) values ('1', '3');
-insert into Friendship (user1_id, user2_id) values ('1', '4');
-insert into Friendship (user1_id, user2_id) values ('2', '3');
-insert into Friendship (user1_id, user2_id) values ('2', '4');
-insert into Friendship (user1_id, user2_id) values ('2', '5');
-insert into Friendship (user1_id, user2_id) values ('6', '1');
-Truncate table Likes;
-insert into Likes (user_id, page_id) values ('1', '88');
-insert into Likes (user_id, page_id) values ('2', '23');
-insert into Likes (user_id, page_id) values ('3', '24');
-insert into Likes (user_id, page_id) values ('4', '56');
-insert into Likes (user_id, page_id) values ('5', '11');
-insert into Likes (user_id, page_id) values ('6', '33');
-insert into Likes (user_id, page_id) values ('2', '77');
-insert into Likes (user_id, page_id) values ('3', '77');
-insert into Likes (user_id, page_id) values ('6', '88');
diff --git a/problems/paint-fence/README.md b/problems/paint-fence/README.md
deleted file mode 100644
index 508201a5d..000000000
--- a/problems/paint-fence/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../h-index-ii "H-Index II")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-celebrity "Find the Celebrity")
-
-## [276. Paint Fence (Medium)](https://leetcode.com/problems/paint-fence "栅栏涂色")
-
-<p>There is a fence with n posts, each post can be painted with one of the k colors.</p>
-
-<p>You have to paint all the posts such that no more than two adjacent fence posts have the same color.</p>
-
-<p>Return the total number of ways you can paint the fence.</p>
-
-<p><b>Note:</b><br />
-n and k are non-negative integers.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-<b>Input:</b> n = 3, k = 2
-<b>Output:</b> 6
-<strong>Explanation: </strong>Take c1 as color 1, c2 as color 2. All possible ways are:
-
-&nbsp;           post1  post2  post3      
- -----      -----  -----  -----       
-   1         c1     c1     c2 
-&nbsp;  2         c1     c2     c1 
-&nbsp;  3         c1     c2     c2 
-&nbsp;  4         c2     c1     c1&nbsp; 
-   5         c2     c1     c2
-&nbsp;  6         c2     c2     c1
-</pre>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [House Robber](../house-robber) (Medium)
-  1. [House Robber II](../house-robber-ii) (Medium)
-  1. [Paint House](../paint-house) (Medium)
-  1. [Paint House II](../paint-house-ii) (Hard)
diff --git a/problems/paint-fence/paint_fence.go b/problems/paint-fence/paint_fence.go
deleted file mode 100644
index 0a0df6e74..000000000
--- a/problems/paint-fence/paint_fence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem276
diff --git a/problems/paint-fence/paint_fence_test.go b/problems/paint-fence/paint_fence_test.go
deleted file mode 100644
index 0a0df6e74..000000000
--- a/problems/paint-fence/paint_fence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem276
diff --git a/problems/paint-house-ii/README.md b/problems/paint-house-ii/README.md
deleted file mode 100644
index 79c853a1c..000000000
--- a/problems/paint-house-ii/README.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ugly-number-ii "Ugly Number II")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-permutation "Palindrome Permutation")
-
-## [265. Paint House II (Hard)](https://leetcode.com/problems/paint-house-ii "粉刷房子 II")
-
-<p>There are a row of <i>n</i> houses, each house can be painted with one of the <i>k</i> colors. The cost of painting each house with a certain color is different. You have to paint all the houses such that no two adjacent houses have the same color.</p>
-
-<p>The cost of painting each house with a certain color is represented by a <code><i>n</i> x <i>k</i></code> cost matrix. For example, <code>costs[0][0]</code> is the cost of painting house 0 with color 0; <code>costs[1][2]</code> is the cost of painting house 1 with color 2, and so on... Find the minimum cost to paint all houses.</p>
-
-<p><b>Note:</b><br />
-All costs are positive integers.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> [[1,5,3],[2,9,4]]
-<strong>Output:</strong> 5
-<strong>Explanation: </strong>Paint house 0 into color 0, paint house 1 into color 2. Minimum cost: 1 + 4 = 5; 
-&nbsp;            Or paint house 0 into color 2, paint house 1 into color 0. Minimum cost: 3 + 2 = 5. 
-</pre>
-
-<p><b>Follow up:</b><br />
-Could you solve it in <i>O</i>(<i>nk</i>) runtime?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Product of Array Except Self](../product-of-array-except-self) (Medium)
-  1. [Sliding Window Maximum](../sliding-window-maximum) (Hard)
-  1. [Paint House](../paint-house) (Medium)
-  1. [Paint Fence](../paint-fence) (Medium)
diff --git a/problems/paint-house-ii/paint_house_ii.go b/problems/paint-house-ii/paint_house_ii.go
deleted file mode 100644
index db93cb337..000000000
--- a/problems/paint-house-ii/paint_house_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem265
diff --git a/problems/paint-house-ii/paint_house_ii_test.go b/problems/paint-house-ii/paint_house_ii_test.go
deleted file mode 100644
index db93cb337..000000000
--- a/problems/paint-house-ii/paint_house_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem265
diff --git a/problems/paint-house-iii/README.md b/problems/paint-house-iii/README.md
deleted file mode 100644
index 2edda59c6..000000000
--- a/problems/paint-house-iii/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-browser-history "Design Browser History")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-n-nodes-after-m-nodes-of-a-linked-list "Delete N Nodes After M Nodes of a Linked List")
-
-## [1473. Paint House III (Hard)](https://leetcode.com/problems/paint-house-iii "粉刷房子 III")
-
-<p>There is a row of <code>m</code> houses in a small city, each house must be painted with one of the <code>n</code> colors (labeled from <code>1</code> to <code>n</code>), some houses that have been painted last summer should not be painted again.</p>
-
-<p>A neighborhood is a maximal group of continuous houses that are painted with the same color.</p>
-
-<ul>
-	<li>For example: <code>houses = [1,2,2,3,3,2,1,1]</code> contains <code>5</code> neighborhoods <code>[{1}, {2,2}, {3,3}, {2}, {1,1}]</code>.</li>
-</ul>
-
-<p>Given an array <code>houses</code>, an <code>m x n</code> matrix <code>cost</code> and an integer <code>target</code> where:</p>
-
-<ul>
-	<li><code>houses[i]</code>: is the color of the house <code>i</code>, and <code>0</code> if the house is not painted yet.</li>
-	<li><code>cost[i][j]</code>: is the cost of paint the house <code>i</code> with the color <code>j + 1</code>.</li>
-</ul>
-
-<p>Return <em>the minimum cost of painting all the remaining houses in such a way that there are exactly</em> <code>target</code> <em>neighborhoods</em>. If it is not possible, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> houses = [0,0,0,0,0], cost = [[1,10],[10,1],[10,1],[1,10],[5,1]], m = 5, n = 2, target = 3
-<strong>Output:</strong> 9
-<strong>Explanation:</strong> Paint houses of this way [1,2,2,1,1]
-This array contains target = 3 neighborhoods, [{1}, {2,2}, {1,1}].
-Cost of paint all houses (1 + 1 + 1 + 1 + 5) = 9.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> houses = [0,2,1,2,0], cost = [[1,10],[10,1],[10,1],[1,10],[5,1]], m = 5, n = 2, target = 3
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> Some houses are already painted, Paint the houses of this way [2,2,1,2,2]
-This array contains target = 3 neighborhoods, [{2,2}, {1}, {2,2}]. 
-Cost of paint the first and last house (10 + 1) = 11.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> houses = [3,1,2,3], cost = [[1,1,1],[1,1,1],[1,1,1],[1,1,1]], m = 4, n = 3, target = 3
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> Houses are already painted with a total of 4 neighborhoods [{3},{1},{2},{3}] different of target = 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == houses.length == cost.length</code></li>
-	<li><code>n == cost[i].length</code></li>
-	<li><code>1 &lt;= m &lt;= 100</code></li>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-	<li><code>1 &lt;= target &lt;= m</code></li>
-	<li><code>0 &lt;= houses[i] &lt;= n</code></li>
-	<li><code>1 &lt;= cost[i][j] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use Dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Define dp[i][j][k] as the minimum cost where we have k neighborhoods in the first i houses and the i-th house is painted with the color j.
-</details>
diff --git a/problems/paint-house/README.md b/problems/paint-house/README.md
deleted file mode 100644
index 4c8b8ad64..000000000
--- a/problems/paint-house/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../verify-preorder-sequence-in-binary-search-tree "Verify Preorder Sequence in Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-paths "Binary Tree Paths")
-
-## [256. Paint House (Medium)](https://leetcode.com/problems/paint-house "粉刷房子")
-
-<p>There are a row of <i>n</i> houses, each house can be painted with one of the three colors: red, blue or green. The cost of painting each house with a certain color is different. You have to paint all the houses such that no two adjacent houses have the same color.</p>
-
-<p>The cost of painting each house with a certain color is represented by a <code><i>n</i> x <i>3</i></code> cost matrix. For example, <code>costs[0][0]</code> is the cost of painting house 0 with color red; <code>costs[1][2]</code> is the cost of painting house 1 with color green, and so on... Find the minimum cost to paint all houses.</p>
-
-<p><b>Note:</b><br />
-All costs are positive integers.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> [[17,2,17],[16,16,5],[14,3,19]]
-<strong>Output:</strong> 10
-<strong>Explanation: </strong>Paint house 0 into blue, paint house 1 into green, paint house 2 into blue. 
-&nbsp;            Minimum cost: 2 + 5 + 3 = 10.
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [House Robber](../house-robber) (Medium)
-  1. [House Robber II](../house-robber-ii) (Medium)
-  1. [Paint House II](../paint-house-ii) (Hard)
-  1. [Paint Fence](../paint-fence) (Medium)
diff --git a/problems/paint-house/paint_house.go b/problems/paint-house/paint_house.go
deleted file mode 100644
index ba2cfddf6..000000000
--- a/problems/paint-house/paint_house.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem256
diff --git a/problems/paint-house/paint_house_test.go b/problems/paint-house/paint_house_test.go
deleted file mode 100644
index ba2cfddf6..000000000
--- a/problems/paint-house/paint_house_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem256
diff --git a/problems/painting-a-grid-with-three-different-colors/README.md b/problems/painting-a-grid-with-three-different-colors/README.md
deleted file mode 100644
index 381805838..000000000
--- a/problems/painting-a-grid-with-three-different-colors/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-length-3-palindromic-subsequences "Unique Length-3 Palindromic Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../merge-bsts-to-create-single-bst "Merge BSTs to Create Single BST")
-
-## [1931. Painting a Grid With Three Different Colors (Hard)](https://leetcode.com/problems/painting-a-grid-with-three-different-colors "用三种不同颜色为网格涂色")
-
-<p>You are given two integers <code>m</code> and <code>n</code>. Consider an <code>m x n</code> grid where each cell is initially white. You can paint each cell <strong>red</strong>, <strong>green</strong>, or <strong>blue</strong>. All cells <strong>must</strong> be painted.</p>
-
-<p>Return<em> the number of ways to color the grid with <strong>no two adjacent cells having the same color</strong></em>. Since the answer can be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/22/colorthegrid.png" style="width: 200px; height: 50px;" />
-<pre>
-<strong>Input:</strong> m = 1, n = 1
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The three possible colorings are shown in the image above.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/22/copy-of-colorthegrid.png" style="width: 321px; height: 121px;" />
-<pre>
-<strong>Input:</strong> m = 1, n = 2
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The six possible colorings are shown in the image above.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> m = 5, n = 5
-<strong>Output:</strong> 580986
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m &lt;= 5</code></li>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Represent each colored column by a bitmask based on each cell color.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use bitmasks DP with state (currentCell, prevColumn).
-</details>
diff --git a/problems/pairs-of-songs-with-total-durations-divisible-by-60/README.md b/problems/pairs-of-songs-with-total-durations-divisible-by-60/README.md
deleted file mode 100644
index f2a3f7713..000000000
--- a/problems/pairs-of-songs-with-total-durations-divisible-by-60/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../complement-of-base-10-integer "Complement of Base 10 Integer")
-　　　　　　　　　　　　　　　　
-[Next >](../capacity-to-ship-packages-within-d-days "Capacity To Ship Packages Within D Days")
-
-## [1010. Pairs of Songs With Total Durations Divisible by 60 (Medium)](https://leetcode.com/problems/pairs-of-songs-with-total-durations-divisible-by-60 "总持续时间可被 60 整除的歌曲")
-
-<p>You are given a list of songs where the i<sup>th</sup> song has a duration of <code>time[i]</code> seconds.</p>
-
-<p>Return <em>the number of pairs of songs for which their total duration in seconds is divisible by</em> <code>60</code>. Formally, we want the number of indices <code>i</code>, <code>j</code> such that <code>i &lt; j</code> with <code>(time[i] + time[j]) % 60 == 0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> time = [30,20,150,100,40]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Three pairs have a total duration divisible by 60:
-(time[0] = 30, time[2] = 150): total duration 180
-(time[1] = 20, time[3] = 100): total duration 120
-(time[1] = 20, time[4] = 40): total duration 60
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> time = [60,60,60]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> All three pairs have a total duration of 120, which is divisible by 60.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= time.length &lt;= 6 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= time[i] &lt;= 500</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We only need to consider each song length modulo 60.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can count the number of songs with (length % 60) equal to r, and store that in an array of size 60.
-</details>
diff --git a/problems/pairs-of-songs-with-total-durations-divisible-by-60/pairs_of_songs_with_total_durations_divisible_by_60.go b/problems/pairs-of-songs-with-total-durations-divisible-by-60/pairs_of_songs_with_total_durations_divisible_by_60.go
deleted file mode 100644
index a221e4fc0..000000000
--- a/problems/pairs-of-songs-with-total-durations-divisible-by-60/pairs_of_songs_with_total_durations_divisible_by_60.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem1010
-
-func numPairsDivisibleBy60(time []int) int {
-	ans, m := 0, [60]int{}
-	for _, t := range time {
-		ans += m[(60-t%60)%60]
-		m[t%60]++
-	}
-	return ans
-}
diff --git a/problems/pairs-of-songs-with-total-durations-divisible-by-60/pairs_of_songs_with_total_durations_divisible_by_60_test.go b/problems/pairs-of-songs-with-total-durations-divisible-by-60/pairs_of_songs_with_total_durations_divisible_by_60_test.go
deleted file mode 100644
index 15c675a6d..000000000
--- a/problems/pairs-of-songs-with-total-durations-divisible-by-60/pairs_of_songs_with_total_durations_divisible_by_60_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem1010
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestNumPairsDivisibleBy60(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{30, 20, 150, 100, 40},
-			want: 3,
-		},
-		{
-			in:   []int{60, 60, 60},
-			want: 3,
-		},
-	}
-	for _, tt := range tests {
-		got := numPairsDivisibleBy60(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/palindrome-linked-list/README.md b/problems/palindrome-linked-list/README.md
deleted file mode 100644
index 95753900b..000000000
--- a/problems/palindrome-linked-list/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-digit-one "Number of Digit One")
-　　　　　　　　　　　　　　　　
-[Next >](../lowest-common-ancestor-of-a-binary-search-tree "Lowest Common Ancestor of a Binary Search Tree")
-
-## [234. Palindrome Linked List (Easy)](https://leetcode.com/problems/palindrome-linked-list "回文链表")
-
-<p>Given the <code>head</code> of a singly linked list, return <code>true</code> if it is a palindrome.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/03/pal1linked-list.jpg" style="width: 422px; height: 62px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,2,1]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/03/pal2linked-list.jpg" style="width: 182px; height: 62px;" />
-<pre>
-<strong>Input:</strong> head = [1,2]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 9</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you do it in <code>O(n)</code> time and <code>O(1)</code> space?
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Palindrome Number](../palindrome-number) (Easy)
-  1. [Valid Palindrome](../valid-palindrome) (Easy)
-  1. [Reverse Linked List](../reverse-linked-list) (Easy)
diff --git a/problems/palindrome-linked-list/palindrome_linked_list.go b/problems/palindrome-linked-list/palindrome_linked_list.go
deleted file mode 100644
index 03d22883d..000000000
--- a/problems/palindrome-linked-list/palindrome_linked_list.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem234
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func isPalindrome(head *ListNode) bool {
-	var prev *ListNode
-	slow, fast := head, head
-	for fast != nil && fast.Next != nil {
-		slow, fast = slow.Next, fast.Next.Next
-	}
-	for slow != nil {
-		prev, slow, slow.Next = slow, slow.Next, prev
-	}
-	for head != nil && prev != nil {
-		if head.Val != prev.Val {
-			return false
-		}
-		head, prev = head.Next, prev.Next
-	}
-	return true
-}
diff --git a/problems/palindrome-linked-list/palindrome_linked_list_test.go b/problems/palindrome-linked-list/palindrome_linked_list_test.go
deleted file mode 100644
index 01e9ded68..000000000
--- a/problems/palindrome-linked-list/palindrome_linked_list_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem234
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestIsPalindrome(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2},
-			want: false,
-		},
-		{
-			in:   []int{1, 2, 1},
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 2, 1},
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := isPalindrome(kit.SliceInt2ListNode(tt.in))
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/palindrome-number/README.md b/problems/palindrome-number/README.md
deleted file mode 100644
index 442e51538..000000000
--- a/problems/palindrome-number/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../string-to-integer-atoi "String to Integer (atoi)")
-　　　　　　　　　　　　　　　　
-[Next >](../regular-expression-matching "Regular Expression Matching")
-
-## [9. Palindrome Number (Easy)](https://leetcode.com/problems/palindrome-number "回文数")
-
-<p>Given an integer <code>x</code>, return <code>true</code> if <code>x</code> is palindrome integer.</p>
-
-<p>An integer is a <strong>palindrome</strong> when it reads the same backward as forward. For example, <code>121</code> is palindrome while <code>123</code> is not.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 121
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = -121
-<strong>Output:</strong> false
-<strong>Explanation:</strong> From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 10
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Reads 01 from right to left. Therefore it is not a palindrome.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = -101
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup>&nbsp;&lt;= x &lt;= 2<sup>31</sup>&nbsp;- 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you solve it without converting the integer to a string?
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Palindrome Linked List](../palindrome-linked-list) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Beware of overflow when you reverse the integer.
-</details>
diff --git a/problems/palindrome-number/palindrome_number.go b/problems/palindrome-number/palindrome_number.go
deleted file mode 100644
index cd5492197..000000000
--- a/problems/palindrome-number/palindrome_number.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem9
-
-func isPalindrome(x int) bool {
-	if x < 0 {
-		return false
-	}
-	rx, t := 0, 0
-	n := x
-	for x != 0 {
-		t = rx*10 + x%10
-		rx = t
-		x /= 10
-	}
-	return rx == n
-}
diff --git a/problems/palindrome-number/palindrome_number_test.go b/problems/palindrome-number/palindrome_number_test.go
deleted file mode 100644
index 67de9186b..000000000
--- a/problems/palindrome-number/palindrome_number_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem9
-
-import (
-	"math"
-	"testing"
-)
-
-func TestIsPalindrome(t *testing.T) {
-	tests := map[int]bool{
-		0:             true,
-		121:           true,
-		12321:         true,
-		123321:        true,
-		-121:          false,
-		10:            false,
-		100:           false,
-		12345:         false,
-		math.MaxInt32: false,
-	}
-
-	for in, want := range tests {
-		got := isPalindrome(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/palindrome-pairs/README.md b/problems/palindrome-pairs/README.md
deleted file mode 100644
index 05b89368f..000000000
--- a/problems/palindrome-pairs/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../self-crossing "Self Crossing")
-　　　　　　　　　　　　　　　　
-[Next >](../house-robber-iii "House Robber III")
-
-## [336. Palindrome Pairs (Hard)](https://leetcode.com/problems/palindrome-pairs "回文对")
-
-<p>Given a list of <b>unique</b> words, return all the pairs of the&nbsp;<b><i>distinct</i></b> indices <code>(i, j)</code> in the given list, so that the concatenation of the two words&nbsp;<code>words[i] + words[j]</code> is a palindrome.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;abcd&quot;,&quot;dcba&quot;,&quot;lls&quot;,&quot;s&quot;,&quot;sssll&quot;]
-<strong>Output:</strong> [[0,1],[1,0],[3,2],[2,4]]
-<strong>Explanation:</strong> The palindromes are [&quot;dcbaabcd&quot;,&quot;abcddcba&quot;,&quot;slls&quot;,&quot;llssssll&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;bat&quot;,&quot;tab&quot;,&quot;cat&quot;]
-<strong>Output:</strong> [[0,1],[1,0]]
-<strong>Explanation:</strong> The palindromes are [&quot;battab&quot;,&quot;tabbat&quot;]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;a&quot;,&quot;&quot;]
-<strong>Output:</strong> [[0,1],[1,0]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 5000</code></li>
-	<li><code>0 &lt;= words[i].length &lt;= 300</code></li>
-	<li><code>words[i]</code> consists of lower-case English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Similar Questions
-  1. [Longest Palindromic Substring](../longest-palindromic-substring) (Medium)
-  1. [Shortest Palindrome](../shortest-palindrome) (Hard)
-  1. [Longest Palindrome by Concatenating Two Letter Words](../longest-palindrome-by-concatenating-two-letter-words) (Medium)
diff --git a/problems/palindrome-pairs/palindrome_pairs.go b/problems/palindrome-pairs/palindrome_pairs.go
deleted file mode 100644
index 981d2efd4..000000000
--- a/problems/palindrome-pairs/palindrome_pairs.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem336
diff --git a/problems/palindrome-pairs/palindrome_pairs_test.go b/problems/palindrome-pairs/palindrome_pairs_test.go
deleted file mode 100644
index 981d2efd4..000000000
--- a/problems/palindrome-pairs/palindrome_pairs_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem336
diff --git a/problems/palindrome-partitioning-ii/README.md b/problems/palindrome-partitioning-ii/README.md
deleted file mode 100644
index 2473475be..000000000
--- a/problems/palindrome-partitioning-ii/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-partitioning "Palindrome Partitioning")
-　　　　　　　　　　　　　　　　
-[Next >](../clone-graph "Clone Graph")
-
-## [132. Palindrome Partitioning II (Hard)](https://leetcode.com/problems/palindrome-partitioning-ii "分割回文串 II")
-
-<p>Given a string <code>s</code>, partition <code>s</code> such that every substring of the partition is a palindrome.</p>
-
-<p>Return <em>the minimum cuts needed</em> for a palindrome partitioning of <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aab&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The palindrome partitioning [&quot;aa&quot;,&quot;b&quot;] could be produced using 1 cut.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a&quot;
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ab&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 2000</code></li>
-	<li><code>s</code> consists of lower-case English letters only.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Palindrome Partitioning](../palindrome-partitioning) (Medium)
-  1. [Palindrome Partitioning IV](../palindrome-partitioning-iv) (Hard)
diff --git a/problems/palindrome-partitioning-ii/palindrome_partitioning_ii.go b/problems/palindrome-partitioning-ii/palindrome_partitioning_ii.go
deleted file mode 100644
index 065ac866a..000000000
--- a/problems/palindrome-partitioning-ii/palindrome_partitioning_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem132
diff --git a/problems/palindrome-partitioning-ii/palindrome_partitioning_ii_test.go b/problems/palindrome-partitioning-ii/palindrome_partitioning_ii_test.go
deleted file mode 100644
index 065ac866a..000000000
--- a/problems/palindrome-partitioning-ii/palindrome_partitioning_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem132
diff --git a/problems/palindrome-partitioning-iii/README.md b/problems/palindrome-partitioning-iii/README.md
deleted file mode 100644
index 8116ce7c1..000000000
--- a/problems/palindrome-partitioning-iii/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-square-submatrices-with-all-ones "Count Square Submatrices with All Ones")
-　　　　　　　　　　　　　　　　
-[Next >](../traffic-light-controlled-intersection "Traffic Light Controlled Intersection")
-
-## [1278. Palindrome Partitioning III (Hard)](https://leetcode.com/problems/palindrome-partitioning-iii "分割回文串 III")
-
-<p>You are given a string <code>s</code> containing lowercase letters and an integer <code>k</code>. You need to :</p>
-
-<ul>
-	<li>First, change some characters of <code>s</code> to other lowercase English letters.</li>
-	<li>Then divide <code>s</code> into <code>k</code> non-empty disjoint substrings such that each substring is a palindrome.</li>
-</ul>
-
-<p>Return <em>the minimal number of characters that you need to change to divide the string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;, k = 2
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>&nbsp;You can split the string into &quot;ab&quot; and &quot;c&quot;, and change 1 character in &quot;ab&quot; to make it palindrome.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabbc&quot;, k = 3
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>&nbsp;You can split the string into &quot;aa&quot;, &quot;bb&quot; and &quot;c&quot;, all of them are palindrome.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;, k = 8
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= s.length &lt;= 100</code>.</li>
-	<li><code>s</code> only contains lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Palindrome Partitioning IV](../palindrome-partitioning-iv) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each substring calculate the minimum number of steps to make it palindrome and store it in a table.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Create a dp(pos, cnt) which means the minimum number of characters changed for the suffix of s starting on pos splitting the suffix on cnt chunks.
-</details>
diff --git a/problems/palindrome-partitioning-iv/README.md b/problems/palindrome-partitioning-iv/README.md
deleted file mode 100644
index 360b484e8..000000000
--- a/problems/palindrome-partitioning-iv/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../can-you-eat-your-favorite-candy-on-your-favorite-day "Can You Eat Your Favorite Candy on Your Favorite Day?")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-subarray-sum-after-one-operation "Maximum Subarray Sum After One Operation")
-
-## [1745. Palindrome Partitioning IV (Hard)](https://leetcode.com/problems/palindrome-partitioning-iv "回文串分割 IV")
-
-<p>Given a string <code>s</code>, return <code>true</code> <em>if it is possible to split the string</em> <code>s</code> <em>into three <strong>non-empty</strong> palindromic substrings. Otherwise, return </em><code>false</code>.​​​​​</p>
-
-<p>A string is said to be palindrome if it the same string when reversed.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcbdd&quot;
-<strong>Output:</strong> true
-<strong>Explanation: </strong>&quot;abcbdd&quot; = &quot;a&quot; + &quot;bcb&quot; + &quot;dd&quot;, and all three substrings are palindromes.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bcbddxy&quot;
-<strong>Output:</strong> false
-<strong>Explanation: </strong>s cannot be split into 3 palindromes.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= s.length &lt;= 2000</code></li>
-	<li><code>s</code>​​​​​​ consists only of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Preprocess checking palindromes in O(1)
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Note that one string is a prefix and another one is a suffix you can try brute forcing the rest
-</details>
diff --git a/problems/palindrome-partitioning/README.md b/problems/palindrome-partitioning/README.md
deleted file mode 100644
index 22a3c6719..000000000
--- a/problems/palindrome-partitioning/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../surrounded-regions "Surrounded Regions")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-partitioning-ii "Palindrome Partitioning II")
-
-## [131. Palindrome Partitioning (Medium)](https://leetcode.com/problems/palindrome-partitioning "分割回文串")
-
-<p>Given a string <code>s</code>, partition <code>s</code> such that every substring of the partition is a <strong>palindrome</strong>. Return all possible palindrome partitioning of <code>s</code>.</p>
-
-<p>A <strong>palindrome</strong> string is a string that reads the same backward as forward.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "aab"
-<strong>Output:</strong> [["a","a","b"],["aa","b"]]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "a"
-<strong>Output:</strong> [["a"]]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 16</code></li>
-	<li><code>s</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Palindrome Partitioning II](../palindrome-partitioning-ii) (Hard)
diff --git a/problems/palindrome-partitioning/palindrome_partitioning.go b/problems/palindrome-partitioning/palindrome_partitioning.go
deleted file mode 100644
index 89b272b72..000000000
--- a/problems/palindrome-partitioning/palindrome_partitioning.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem131
diff --git a/problems/palindrome-partitioning/palindrome_partitioning_test.go b/problems/palindrome-partitioning/palindrome_partitioning_test.go
deleted file mode 100644
index 89b272b72..000000000
--- a/problems/palindrome-partitioning/palindrome_partitioning_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem131
diff --git a/problems/palindrome-permutation-ii/README.md b/problems/palindrome-permutation-ii/README.md
deleted file mode 100644
index 8b50ed57e..000000000
--- a/problems/palindrome-permutation-ii/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-permutation "Palindrome Permutation")
-　　　　　　　　　　　　　　　　
-[Next >](../missing-number "Missing Number")
-
-## [267. Palindrome Permutation II (Medium)](https://leetcode.com/problems/palindrome-permutation-ii "回文排列 II")
-
-<p>Given a string <code>s</code>, return all the palindromic permutations (without duplicates) of it. Return an empty list if no palindromic permutation could be form.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre><strong>Input:</strong> <code>&quot;aabb&quot;</code>
-<strong>Output:</strong> <code>[&quot;abba&quot;, &quot;baab&quot;]</code></pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre><strong>Input:</strong> <code>&quot;abc&quot;</code>
-<strong>Output:</strong> <code>[]</code></pre>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Next Permutation](../next-permutation) (Medium)
-  1. [Permutations II](../permutations-ii) (Medium)
-  1. [Palindrome Permutation](../palindrome-permutation) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If a palindromic permutation exists, we just need to generate the first half of the string.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To generate all distinct permutations of a (half of) string, use a similar approach from: <a href="/problems/permutations-ii">Permutations II</a> or <a href="/problems/next-permutation">Next Permutation</a>.
-</details>
diff --git a/problems/palindrome-permutation-ii/palindrome_permutation_ii.go b/problems/palindrome-permutation-ii/palindrome_permutation_ii.go
deleted file mode 100644
index 1f171637f..000000000
--- a/problems/palindrome-permutation-ii/palindrome_permutation_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem267
diff --git a/problems/palindrome-permutation-ii/palindrome_permutation_ii_test.go b/problems/palindrome-permutation-ii/palindrome_permutation_ii_test.go
deleted file mode 100644
index 1f171637f..000000000
--- a/problems/palindrome-permutation-ii/palindrome_permutation_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem267
diff --git a/problems/palindrome-permutation/README.md b/problems/palindrome-permutation/README.md
deleted file mode 100644
index 26442c494..000000000
--- a/problems/palindrome-permutation/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../paint-house-ii "Paint House II")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-permutation-ii "Palindrome Permutation II")
-
-## [266. Palindrome Permutation (Easy)](https://leetcode.com/problems/palindrome-permutation "回文排列")
-
-<p>Given a string, determine if a permutation of the string could form a palindrome.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre><strong>Input:</strong> <code>&quot;code&quot;</code>
-<strong>Output:</strong> false</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre><strong>Input:</strong> <code>&quot;aab&quot;</code>
-<strong>Output:</strong> true</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre><strong>Input:</strong> <code>&quot;carerac&quot;</code>
-<strong>Output:</strong> true</pre>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Longest Palindromic Substring](../longest-palindromic-substring) (Medium)
-  1. [Valid Anagram](../valid-anagram) (Easy)
-  1. [Palindrome Permutation II](../palindrome-permutation-ii) (Medium)
-  1. [Longest Palindrome](../longest-palindrome) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider the palindromes of odd vs even length. What difference do you notice?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Count the frequency of each character.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If each character occurs even number of times, then it must be a palindrome. How about character which occurs odd number of times?
-</details>
diff --git a/problems/palindrome-permutation/palindrome_permutation.go b/problems/palindrome-permutation/palindrome_permutation.go
deleted file mode 100644
index 05c029670..000000000
--- a/problems/palindrome-permutation/palindrome_permutation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem266
diff --git a/problems/palindrome-permutation/palindrome_permutation_test.go b/problems/palindrome-permutation/palindrome_permutation_test.go
deleted file mode 100644
index 05c029670..000000000
--- a/problems/palindrome-permutation/palindrome_permutation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem266
diff --git a/problems/palindrome-removal/README.md b/problems/palindrome-removal/README.md
deleted file mode 100644
index f7b82a429..000000000
--- a/problems/palindrome-removal/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tree-diameter "Tree Diameter")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-swaps-to-make-strings-equal "Minimum Swaps to Make Strings Equal")
-
-## [1246. Palindrome Removal (Hard)](https://leetcode.com/problems/palindrome-removal "删除回文子数组")
-
-<p>Given an integer array&nbsp;<code>arr</code>, in one move you can select a <strong>palindromic</strong>&nbsp;subarray <code>arr[i], arr[i+1], ..., arr[j]</code>&nbsp;where <code>i &lt;= j</code>, and remove that subarray from the given array. Note that after removing a subarray, the elements on the left and on the right of that subarray move to fill the gap left by the removal.</p>
-
-<p>Return the minimum number of moves needed&nbsp;to remove all numbers from the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,3,4,1,5]
-<strong>Output:</strong> 3
-<b>Explanation: </b>Remove [4] then remove [1,3,1] then remove [5].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 100</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 20</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let dp[i][j] be the solution for the sub-array from index i to index j.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Notice that if we have S[i] == S[j] one transition could be just dp(i + 1, j + 1) because in the last turn we would have a palindrome and we can extend this palindrome from both sides, the other transitions are not too difficult to deduce.
-</details>
diff --git a/problems/palindromic-substrings/README.md b/problems/palindromic-substrings/README.md
deleted file mode 100644
index 878a0a02e..000000000
--- a/problems/palindromic-substrings/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-length-of-pair-chain "Maximum Length of Pair Chain")
-　　　　　　　　　　　　　　　　
-[Next >](../replace-words "Replace Words")
-
-## [647. Palindromic Substrings (Medium)](https://leetcode.com/problems/palindromic-substrings "回文子串")
-
-<p>Given a string <code>s</code>, return <em>the number of <strong>palindromic substrings</strong> in it</em>.</p>
-
-<p>A string is a <strong>palindrome</strong> when it reads the same backward as forward.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within the string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Three palindromic strings: &quot;a&quot;, &quot;b&quot;, &quot;c&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaa&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Six palindromic strings: &quot;a&quot;, &quot;a&quot;, &quot;a&quot;, &quot;aa&quot;, &quot;aa&quot;, &quot;aaa&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Longest Palindromic Substring](../longest-palindromic-substring) (Medium)
-  1. [Longest Palindromic Subsequence](../longest-palindromic-subsequence) (Medium)
-  1. [Palindromic Substrings](../palindromic-substrings) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can we reuse a previously computed palindrome to compute a larger palindrome?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If “aba” is a palindrome, is “xabax” and palindrome? Similarly is “xabay” a palindrome?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Complexity based hint:</br>
-If we use brute-force and check whether for every start and end position a substring is a palindrome we have O(n^2) start - end pairs and O(n) palindromic checks. Can we reduce the time for palindromic checks to O(1) by reusing some previous computation?
-</details>
diff --git a/problems/palindromic-substrings/palindromic_substrings.go b/problems/palindromic-substrings/palindromic_substrings.go
deleted file mode 100644
index 79ac502a8..000000000
--- a/problems/palindromic-substrings/palindromic_substrings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem647
diff --git a/problems/palindromic-substrings/palindromic_substrings_test.go b/problems/palindromic-substrings/palindromic_substrings_test.go
deleted file mode 100644
index 79ac502a8..000000000
--- a/problems/palindromic-substrings/palindromic_substrings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem647
diff --git a/problems/pancake-sorting/README.md b/problems/pancake-sorting/README.md
deleted file mode 100644
index 7db0dd175..000000000
--- a/problems/pancake-sorting/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-cameras "Binary Tree Cameras")
-　　　　　　　　　　　　　　　　
-[Next >](../powerful-integers "Powerful Integers")
-
-## [969. Pancake Sorting (Medium)](https://leetcode.com/problems/pancake-sorting "煎饼排序")
-
-<p>Given an array of integers <code>arr</code>, sort the array by performing a series of <strong>pancake flips</strong>.</p>
-
-<p>In one pancake flip we do the following steps:</p>
-
-<ul>
-	<li>Choose an integer <code>k</code> where <code>1 &lt;= k &lt;= arr.length</code>.</li>
-	<li>Reverse the sub-array <code>arr[0...k-1]</code> (<strong>0-indexed</strong>).</li>
-</ul>
-
-<p>For example, if <code>arr = [3,2,1,4]</code> and we performed a pancake flip choosing <code>k = 3</code>, we reverse the sub-array <code>[3,2,1]</code>, so <code>arr = [<u>1</u>,<u>2</u>,<u>3</u>,4]</code> after the pancake flip at <code>k = 3</code>.</p>
-
-<p>Return <em>an array of the </em><code>k</code><em>-values corresponding to a sequence of pancake flips that sort </em><code>arr</code>. Any valid answer that sorts the array within <code>10 * arr.length</code> flips will be judged as correct.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,2,4,1]
-<strong>Output:</strong> [4,2,4,3]
-<strong>Explanation: </strong>
-We perform 4 pancake flips, with k values 4, 2, 4, and 3.
-Starting state: arr = [3, 2, 4, 1]
-After 1st flip (k = 4): arr = [<u>1</u>, <u>4</u>, <u>2</u>, <u>3</u>]
-After 2nd flip (k = 2): arr = [<u>4</u>, <u>1</u>, 2, 3]
-After 3rd flip (k = 4): arr = [<u>3</u>, <u>2</u>, <u>1</u>, <u>4</u>]
-After 4th flip (k = 3): arr = [<u>1</u>, <u>2</u>, <u>3</u>, 4], which is sorted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3]
-<strong>Output:</strong> []
-<strong>Explanation: </strong>The input is already sorted, so there is no need to flip anything.
-Note that other answers, such as [3, 3], would also be accepted.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 100</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= arr.length</code></li>
-	<li>All integers in <code>arr</code> are unique (i.e. <code>arr</code> is a permutation of the integers from <code>1</code> to <code>arr.length</code>).</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/pancake-sorting/pancake_sorting.go b/problems/pancake-sorting/pancake_sorting.go
deleted file mode 100644
index a7846f90f..000000000
--- a/problems/pancake-sorting/pancake_sorting.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem969
diff --git a/problems/parallel-courses-ii/README.md b/problems/parallel-courses-ii/README.md
deleted file mode 100644
index f3ace5883..000000000
--- a/problems/parallel-courses-ii/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-subarray-of-1s-after-deleting-one-element "Longest Subarray of 1's After Deleting One Element")
-　　　　　　　　　　　　　　　　
-[Next >](../friendly-movies-streamed-last-month "Friendly Movies Streamed Last Month")
-
-## [1494. Parallel Courses II (Hard)](https://leetcode.com/problems/parallel-courses-ii "并行课程 II")
-
-<p>You are given an integer <code>n</code>, which indicates that there are <code>n</code> courses labeled from <code>1</code> to <code>n</code>. You are also given an array <code>relations</code> where <code>relations[i] = [prevCourse<sub>i</sub>, nextCourse<sub>i</sub>]</code>, representing a prerequisite relationship between course <code>prevCourse<sub>i</sub></code> and course <code>nextCourse<sub>i</sub></code>: course <code>prevCourse<sub>i</sub></code> has to be taken before course <code>nextCourse<sub>i</sub></code>. Also, you are given the integer <code>k</code>.</p>
-
-<p>In one semester, you can take <strong>at most</strong> <code>k</code> courses as long as you have taken all the prerequisites in the <strong>previous</strong> semester for the courses you are taking.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of semesters needed to take all courses</em>. The testcases will be generated such that it is possible to take every course.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/05/22/leetcode_parallel_courses_1.png" style="width: 300px; height: 164px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, dependencies = [[2,1],[3,1],[1,4]], k = 2
-<strong>Output:</strong> 3 
-<strong>Explanation:</strong> The figure above represents the given graph.
-In the first semester, you can take courses 2 and 3.
-In the second semester, you can take course 1.
-In the third semester, you can take course 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/05/22/leetcode_parallel_courses_2.png" style="width: 300px; height: 234px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, dependencies = [[2,1],[3,1],[4,1],[1,5]], k = 2
-<strong>Output:</strong> 4 
-<strong>Explanation:</strong> The figure above represents the given graph.
-In the first semester, you can take courses 2 and 3 only since you cannot take more than two per semester.
-In the second semester, you can take course 4.
-In the third semester, you can take course 1.
-In the fourth semester, you can take course 5.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 11, dependencies = [], k = 2
-<strong>Output:</strong> 6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 15</code></li>
-	<li><code>1 &lt;= k &lt;= n</code></li>
-	<li><code>0 &lt;= relations.length &lt;= n * (n-1) / 2</code></li>
-	<li><code>relations[i].length == 2</code></li>
-	<li><code>1 &lt;= prevCourse<sub>i</sub>, nextCourse<sub>i</sub> &lt;= n</code></li>
-	<li><code>prevCourse<sub>i</sub> != nextCourse<sub>i</sub></code></li>
-	<li>All the pairs <code>[prevCourse<sub>i</sub>, nextCourse<sub>i</sub>]</code> are <strong>unique</strong>.</li>
-	<li>The given graph is a directed acyclic graph.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use backtracking with states (bitmask, degrees) where bitmask represents the set of courses, if the ith bit is 1 then the ith course was taken, otherwise, you can take the ith course. Degrees represent the degree for each course (nodes in the graph).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Note that you can only take nodes (courses) with degree = 0 and it is optimal at every step in the backtracking take the maximum number of courses limited by k.
-</details>
diff --git a/problems/parallel-courses-iii/README.md b/problems/parallel-courses-iii/README.md
deleted file mode 100644
index ca6fddca5..000000000
--- a/problems/parallel-courses-iii/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-nodes-with-the-highest-score "Count Nodes With the Highest Score")
-　　　　　　　　　　　　　　　　
-[Next >](../the-category-of-each-member-in-the-store "The Category of Each Member in the Store")
-
-## [2050. Parallel Courses III (Hard)](https://leetcode.com/problems/parallel-courses-iii "并行课程 III")
-
-<p>You are given an integer <code>n</code>, which indicates that there are <code>n</code> courses labeled from <code>1</code> to <code>n</code>. You are also given a 2D integer array <code>relations</code> where <code>relations[j] = [prevCourse<sub>j</sub>, nextCourse<sub>j</sub>]</code> denotes that course <code>prevCourse<sub>j</sub></code> has to be completed <strong>before</strong> course <code>nextCourse<sub>j</sub></code> (prerequisite relationship). Furthermore, you are given a <strong>0-indexed</strong> integer array <code>time</code> where <code>time[i]</code> denotes how many <strong>months</strong> it takes to complete the <code>(i+1)<sup>th</sup></code> course.</p>
-
-<p>You must find the <strong>minimum</strong> number of months needed to complete all the courses following these rules:</p>
-
-<ul>
-	<li>You may start taking a course at <strong>any time</strong> if the prerequisites are met.</li>
-	<li><strong>Any number of courses</strong> can be taken at the <strong>same time</strong>.</li>
-</ul>
-
-<p>Return <em>the <strong>minimum</strong> number of months needed to complete all the courses</em>.</p>
-
-<p><strong>Note:</strong> The test cases are generated such that it is possible to complete every course (i.e., the graph is a directed acyclic graph).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<strong><img alt="" src="https://assets.leetcode.com/uploads/2021/10/07/ex1.png" style="width: 392px; height: 232px;" /></strong>
-
-<pre>
-<strong>Input:</strong> n = 3, relations = [[1,3],[2,3]], time = [3,2,5]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> The figure above represents the given graph and the time required to complete each course. 
-We start course 1 and course 2 simultaneously at month 0.
-Course 1 takes 3 months and course 2 takes 2 months to complete respectively.
-Thus, the earliest time we can start course 3 is at month 3, and the total time required is 3 + 5 = 8 months.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<strong><img alt="" src="https://assets.leetcode.com/uploads/2021/10/07/ex2.png" style="width: 500px; height: 365px;" /></strong>
-
-<pre>
-<strong>Input:</strong> n = 5, relations = [[1,5],[2,5],[3,5],[3,4],[4,5]], time = [1,2,3,4,5]
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> The figure above represents the given graph and the time required to complete each course.
-You can start courses 1, 2, and 3 at month 0.
-You can complete them after 1, 2, and 3 months respectively.
-Course 4 can be taken only after course 3 is completed, i.e., after 3 months. It is completed after 3 + 4 = 7 months.
-Course 5 can be taken only after courses 1, 2, 3, and 4 have been completed, i.e., after max(1,2,3,7) = 7 months.
-Thus, the minimum time needed to complete all the courses is 7 + 5 = 12 months.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= relations.length &lt;= min(n * (n - 1) / 2, 5 * 10<sup>4</sup>)</code></li>
-	<li><code>relations[j].length == 2</code></li>
-	<li><code>1 &lt;= prevCourse<sub>j</sub>, nextCourse<sub>j</sub> &lt;= n</code></li>
-	<li><code>prevCourse<sub>j</sub> != nextCourse<sub>j</sub></code></li>
-	<li>All the pairs <code>[prevCourse<sub>j</sub>, nextCourse<sub>j</sub>]</code> are <strong>unique</strong>.</li>
-	<li><code>time.length == n</code></li>
-	<li><code>1 &lt;= time[i] &lt;= 10<sup>4</sup></code></li>
-	<li>The given graph is a directed acyclic graph.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What is the earliest time a course can be taken?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How would you solve the problem if all courses take equal time?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How would you generalize this approach?
-</details>
diff --git a/problems/parallel-courses/README.md b/problems/parallel-courses/README.md
deleted file mode 100644
index ce0d249ab..000000000
--- a/problems/parallel-courses/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../connecting-cities-with-minimum-cost "Connecting Cities With Minimum Cost")
-　　　　　　　　　　　　　　　　
-[Next >](../n-th-tribonacci-number "N-th Tribonacci Number")
-
-## [1136. Parallel Courses (Medium)](https://leetcode.com/problems/parallel-courses "平行课程")
-
-<p>There are <code>N</code> courses, labelled from 1 to <code>N</code>.</p>
-
-<p>We are given&nbsp;<code>relations[i] = [X, Y]</code>, representing a prerequisite relationship between course <code>X</code> and course <code>Y</code>:&nbsp;course <code>X</code>&nbsp;has to be studied before course <code>Y</code>.</p>
-
-<p>In one semester you can study any number of courses as long as you have studied all the prerequisites for the course you are studying.</p>
-
-<p>Return the minimum number of semesters needed to study all courses.&nbsp; If there is no way to study all the courses, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/04/20/1316_ex1.png" style="width: 126px; height: 101px;" /></strong></p>
-
-<pre>
-<strong>Input: </strong>N = <span id="example-input-1-1">3</span>, relations = <span id="example-input-1-2">[[1,3],[2,3]]</span>
-<strong>Output: </strong><span id="example-output-1">2</span>
-<strong>Explanation: </strong>
-In the first semester, courses 1 and 2 are studied. In the second semester, course 3 is studied.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/04/20/1316_ex2.png" style="width: 126px; height: 101px;" /></strong></p>
-
-<pre>
-<strong>Input: </strong>N = <span id="example-input-2-1">3</span>, relations = <span id="example-input-2-2">[[1,2],[2,3],[3,1]]</span>
-<strong>Output: </strong><span id="example-output-2">-1</span>
-<strong>Explanation: </strong>
-No course can be studied because they depend on each other.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong><span>Note:</span></strong></p>
-
-<ol>
-	<li><code>1 &lt;= N &lt;= 5000</code></li>
-	<li><code>1 &lt;= relations.length &lt;= 5000</code></li>
-	<li><code>relations[i][0] != relations[i][1]</code></li>
-	<li>There are no repeated relations in the input.</li>
-</ol>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to think of it as a graph problem. It will be impossible to study all the courses if the graph had a cycle.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The graph is a directed acyclic graph (DAG). The answer is the longes path in this DAG.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can use DP to find the longest path in the DAG.
-</details>
diff --git a/problems/parse-lisp-expression/README.md b/problems/parse-lisp-expression/README.md
deleted file mode 100644
index e75e66ef0..000000000
--- a/problems/parse-lisp-expression/README.md
+++ /dev/null
@@ -1,107 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../asteroid-collision "Asteroid Collision")
-　　　　　　　　　　　　　　　　
-[Next >](../sentence-similarity-ii "Sentence Similarity II")
-
-## [736. Parse Lisp Expression (Hard)](https://leetcode.com/problems/parse-lisp-expression "Lisp 语法解析")
-
-<p>You are given a string expression representing a Lisp-like expression to return the integer value of.</p>
-
-<p>The syntax for these expressions is given as follows.</p>
-
-<ul>
-	<li>An expression is either an integer, let expression, add expression, mult expression, or an assigned variable. Expressions always evaluate to a single integer.</li>
-	<li>(An integer could be positive or negative.)</li>
-	<li>A let expression takes the form <code>&quot;(let v<sub>1</sub> e<sub>1</sub> v<sub>2</sub> e<sub>2</sub> ... v<sub>n</sub> e<sub>n</sub> expr)&quot;</code>, where let is always the string <code>&quot;let&quot;</code>, then there are one or more pairs of alternating variables and expressions, meaning that the first variable <code>v<sub>1</sub></code> is assigned the value of the expression <code>e<sub>1</sub></code>, the second variable <code>v<sub>2</sub></code> is assigned the value of the expression <code>e<sub>2</sub></code>, and so on sequentially; and then the value of this let expression is the value of the expression <code>expr</code>.</li>
-	<li>An add expression takes the form <code>&quot;(add e<sub>1</sub> e<sub>2</sub>)&quot;</code> where add is always the string <code>&quot;add&quot;</code>, there are always two expressions <code>e<sub>1</sub></code>, <code>e<sub>2</sub></code> and the result is the addition of the evaluation of <code>e<sub>1</sub></code> and the evaluation of <code>e<sub>2</sub></code>.</li>
-	<li>A mult expression takes the form <code>&quot;(mult e<sub>1</sub> e<sub>2</sub>)&quot;</code> where mult is always the string <code>&quot;mult&quot;</code>, there are always two expressions <code>e<sub>1</sub></code>, <code>e<sub>2</sub></code> and the result is the multiplication of the evaluation of e1 and the evaluation of e2.</li>
-	<li>For this question, we will use a smaller subset of variable names. A variable starts with a lowercase letter, then zero or more lowercase letters or digits. Additionally, for your convenience, the names <code>&quot;add&quot;</code>, <code>&quot;let&quot;</code>, and <code>&quot;mult&quot;</code> are protected and will never be used as variable names.</li>
-	<li>Finally, there is the concept of scope. When an expression of a variable name is evaluated, within the context of that evaluation, the innermost scope (in terms of parentheses) is checked first for the value of that variable, and then outer scopes are checked sequentially. It is guaranteed that every expression is legal. Please see the examples for more details on the scope.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;(let x 2 (mult x (let x 3 y 4 (add x y))))&quot;
-<strong>Output:</strong> 14
-<strong>Explanation:</strong> In the expression (add x y), when checking for the value of the variable x,
-we check from the innermost scope to the outermost in the context of the variable we are trying to evaluate.
-Since x = 3 is found first, the value of x is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;(let x 3 x 2 x)&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Assignment in let statements is processed sequentially.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;(let x 1 y 2 x (add x y) (add x y))&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The first (add x y) evaluates as 3, and is assigned to x.
-The second (add x y) evaluates as 3+2 = 5.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;(let x 2 (add (let x 3 (let x 4 x)) x))&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Even though (let x 4 x) has a deeper scope, it is outside the context
-of the final x in the add-expression.  That final x will equal 2.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;(let a1 3 b2 (add a1 1) b2)&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Variable names can contain digits after the first character.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= expression.length &lt;= 2000</code></li>
-	<li>There are no leading or trailing spaces in <code>exprssion</code>.</li>
-	<li>All tokens are separated by a single space in <code>expressoin</code>.</li>
-	<li>The answer and all intermediate calculations of that answer are guaranteed to fit in a <strong>32-bit</strong> integer.</li>
-	<li>The expression is guaranteed to be legal and evaluate to an integer.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Ternary Expression Parser](../ternary-expression-parser) (Medium)
-  1. [Number of Atoms](../number-of-atoms) (Hard)
-  1. [Basic Calculator IV](../basic-calculator-iv) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-* If the expression starts with a digit or '-', it's an integer: return it.
-
-* If the expression starts with a letter, it's a variable.  Recall it by checking the current scope in reverse order.
-
-* Otherwise, group the tokens (variables or expressions) within this expression by counting the "balance" `bal` of the occurrences of `'('` minus the number of occurrences of `')'`.  When the balance is zero, we have ended a token.  For example, `(add 1 (add 2 3))` should have tokens `'1'` and `'(add 2 3)'`.
-
-* For add and mult expressions, evaluate each token and return the addition or multiplication of them.
-
-* For let expressions, evaluate each expression sequentially and assign it to the variable in the current scope, then return the evaluation of the final expression.
-</details>
diff --git a/problems/parse-lisp-expression/parse_lisp_expression.go b/problems/parse-lisp-expression/parse_lisp_expression.go
deleted file mode 100644
index 7acc7ad61..000000000
--- a/problems/parse-lisp-expression/parse_lisp_expression.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem736
diff --git a/problems/parse-lisp-expression/parse_lisp_expression_test.go b/problems/parse-lisp-expression/parse_lisp_expression_test.go
deleted file mode 100644
index 7acc7ad61..000000000
--- a/problems/parse-lisp-expression/parse_lisp_expression_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem736
diff --git a/problems/parsing-a-boolean-expression/README.md b/problems/parsing-a-boolean-expression/README.md
deleted file mode 100644
index 9ab927c3f..000000000
--- a/problems/parsing-a-boolean-expression/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../filling-bookcase-shelves "Filling Bookcase Shelves")
-　　　　　　　　　　　　　　　　
-[Next >](../new-users-daily-count "New Users Daily Count")
-
-## [1106. Parsing A Boolean Expression (Hard)](https://leetcode.com/problems/parsing-a-boolean-expression "解析布尔表达式")
-
-<p>Return the result of evaluating a given boolean <code>expression</code>, represented as a string.</p>
-
-<p>An expression can either be:</p>
-
-<ul>
-	<li><code>&quot;t&quot;</code>, evaluating to <code>True</code>;</li>
-	<li><code>&quot;f&quot;</code>, evaluating to <code>False</code>;</li>
-	<li><code>&quot;!(expr)&quot;</code>, evaluating to the logical NOT of the inner expression <code>expr</code>;</li>
-	<li><code>&quot;&amp;(expr1,expr2,...)&quot;</code>, evaluating to the logical AND of 2 or more inner expressions <code>expr1, expr2, ...</code>;</li>
-	<li><code>&quot;|(expr1,expr2,...)&quot;</code>, evaluating to the logical OR of 2 or more inner expressions <code>expr1, expr2, ...</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;!(f)&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;|(f,t)&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;&amp;(t,f)&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> expression = &quot;|(&amp;(t,f,t),!(t))&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= expression.length &lt;= 20000</code></li>
-	<li><code>expression[i]</code>&nbsp;consists of characters in <code>{&#39;(&#39;, &#39;)&#39;, &#39;&amp;&#39;, &#39;|&#39;, &#39;!&#39;, &#39;t&#39;, &#39;f&#39;, &#39;,&#39;}</code>.</li>
-	<li><code>expression</code> is a valid expression representing a boolean, as given in the description.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Write a function "parse" which calls helper functions "parse_or", "parse_and", "parse_not".
-</details>
diff --git a/problems/parsing-a-boolean-expression/parsing_a_boolean_expression.go b/problems/parsing-a-boolean-expression/parsing_a_boolean_expression.go
deleted file mode 100644
index d03249a3f..000000000
--- a/problems/parsing-a-boolean-expression/parsing_a_boolean_expression.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1106
diff --git a/problems/partition-array-according-to-given-pivot/README.md b/problems/partition-array-according-to-given-pivot/README.md
deleted file mode 100644
index c058a818e..000000000
--- a/problems/partition-array-according-to-given-pivot/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-sum-of-four-digit-number-after-splitting-digits "Minimum Sum of Four Digit Number After Splitting Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-set-cooking-time "Minimum Cost to Set Cooking Time")
-
-## [2161. Partition Array According to Given Pivot (Medium)](https://leetcode.com/problems/partition-array-according-to-given-pivot "根据给定数字划分数组")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code> and an integer <code>pivot</code>. Rearrange <code>nums</code> such that the following conditions are satisfied:</p>
-
-<ul>
-	<li>Every element less than <code>pivot</code> appears <strong>before</strong> every element greater than <code>pivot</code>.</li>
-	<li>Every element equal to <code>pivot</code> appears <strong>in between</strong> the elements less than and greater than <code>pivot</code>.</li>
-	<li>The <strong>relative order</strong> of the elements less than <code>pivot</code> and the elements greater than <code>pivot</code> is maintained.
-	<ul>
-		<li>More formally, consider every <code>p<sub>i</sub></code>, <code>p<sub>j</sub></code> where <code>p<sub>i</sub></code> is the new position of the <code>i<sup>th</sup></code> element and <code>p<sub>j</sub></code> is the new position of the <code>j<sup>th</sup></code> element. For elements less than <code>pivot</code>, if <code>i &lt; j</code> and <code>nums[i] &lt; pivot</code> and <code>nums[j] &lt; pivot</code>, then <code>p<sub>i</sub> &lt; p<sub>j</sub></code>. Similarly for elements greater than <code>pivot</code>, if <code>i &lt; j</code> and <code>nums[i] &gt; pivot</code> and <code>nums[j] &gt; pivot</code>, then <code>p<sub>i</sub> &lt; p<sub>j</sub></code>.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <code>nums</code><em> after the rearrangement.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,12,5,10,14,3,10], pivot = 10
-<strong>Output:</strong> [9,5,3,10,10,12,14]
-<strong>Explanation:</strong> 
-The elements 9, 5, and 3 are less than the pivot so they are on the left side of the array.
-The elements 12 and 14 are greater than the pivot so they are on the right side of the array.
-The relative ordering of the elements less than and greater than pivot is also maintained. [9, 5, 3] and [12, 14] are the respective orderings.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-3,4,3,2], pivot = 2
-<strong>Output:</strong> [-3,2,4,3]
-<strong>Explanation:</strong> 
-The element -3 is less than the pivot so it is on the left side of the array.
-The elements 4 and 3 are greater than the pivot so they are on the right side of the array.
-The relative ordering of the elements less than and greater than pivot is also maintained. [-3] and [4, 3] are the respective orderings.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>6</sup> &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>pivot</code> equals to an element of <code>nums</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could you put the elements smaller than the pivot and greater than the pivot in a separate list as in the sequence that they occur?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-With the separate lists generated, could you then generate the result?
-</details>
diff --git a/problems/partition-array-for-maximum-sum/README.md b/problems/partition-array-for-maximum-sum/README.md
deleted file mode 100644
index 0822d49cc..000000000
--- a/problems/partition-array-for-maximum-sum/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flower-planting-with-no-adjacent "Flower Planting With No Adjacent")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-duplicate-substring "Longest Duplicate Substring")
-
-## [1043. Partition Array for Maximum Sum (Medium)](https://leetcode.com/problems/partition-array-for-maximum-sum "分隔数组以得到最大和")
-
-<p>Given an integer array <code>arr</code>, partition the array into (contiguous) subarrays of length <strong>at most</strong> <code>k</code>. After partitioning, each subarray has their values changed to become the maximum value of that subarray.</p>
-
-<p>Return <em>the largest sum of the given array after partitioning. Test cases are generated so that the answer fits in a <strong>32-bit</strong> integer.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,15,7,9,2,5,10], k = 3
-<strong>Output:</strong> 84
-<strong>Explanation:</strong> arr becomes [15,15,15,9,10,10,10]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,4,1,5,7,3,6,1,9,9,3], k = 4
-<strong>Output:</strong> 83
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1], k = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 500</code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= k &lt;= arr.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think dynamic programming:  dp[i] will be the answer for array A[0], ..., A[i-1].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For j = 1 .. k that keeps everything in bounds, dp[i] is the maximum of dp[i-j] + max(A[i-1], ..., A[i-j]) * j .
-</details>
diff --git a/problems/partition-array-for-maximum-sum/partition_array_for_maximum_sum.go b/problems/partition-array-for-maximum-sum/partition_array_for_maximum_sum.go
deleted file mode 100644
index ccff295e8..000000000
--- a/problems/partition-array-for-maximum-sum/partition_array_for_maximum_sum.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem1043
-
-func maxSumAfterPartitioning(A []int, K int) int {
-	n := len(A)
-	dp := make([]int, n+1)
-	// A's length grows up from 1 to n
-	for l := 1; l <= n; l++ {
-		m := 0 // max value of last k items in A[:l]
-		for k := 1; k <= K && 0 <= l-k; k++ {
-			m = max(m, A[l-k])
-			sum := dp[l-k] + m*k
-			dp[l] = max(dp[l], sum)
-		}
-	}
-	return dp[n]
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/partition-array-into-disjoint-intervals/README.md b/problems/partition-array-into-disjoint-intervals/README.md
deleted file mode 100644
index 5a1693ed6..000000000
--- a/problems/partition-array-into-disjoint-intervals/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../x-of-a-kind-in-a-deck-of-cards "X of a Kind in a Deck of Cards")
-　　　　　　　　　　　　　　　　
-[Next >](../word-subsets "Word Subsets")
-
-## [915. Partition Array into Disjoint Intervals (Medium)](https://leetcode.com/problems/partition-array-into-disjoint-intervals "分割数组")
-
-<p>Given an integer array <code>nums</code>, partition it into two (contiguous) subarrays <code>left</code> and <code>right</code> so that:</p>
-
-<ul>
-	<li>Every element in <code>left</code> is less than or equal to every element in <code>right</code>.</li>
-	<li><code>left</code> and <code>right</code> are non-empty.</li>
-	<li><code>left</code> has the smallest possible size.</li>
-</ul>
-
-<p>Return <em>the length of </em><code>left</code><em> after such a partitioning</em>.</p>
-
-<p>Test cases are generated such that partitioning exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,0,3,8,6]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> left = [5,0,3], right = [8,6]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,0,6,12]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> left = [1,1,1,0], right = [6,12]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-	<li>There is at least one valid answer for the given input.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Sum of Beauty in the Array](../sum-of-beauty-in-the-array) (Medium)
diff --git a/problems/partition-array-into-disjoint-intervals/partition_array_into_disjoint_intervals.go b/problems/partition-array-into-disjoint-intervals/partition_array_into_disjoint_intervals.go
deleted file mode 100644
index 57c0c2bef..000000000
--- a/problems/partition-array-into-disjoint-intervals/partition_array_into_disjoint_intervals.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem915
diff --git a/problems/partition-array-into-disjoint-intervals/partition_array_into_disjoint_intervals_test.go b/problems/partition-array-into-disjoint-intervals/partition_array_into_disjoint_intervals_test.go
deleted file mode 100644
index 57c0c2bef..000000000
--- a/problems/partition-array-into-disjoint-intervals/partition_array_into_disjoint_intervals_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem915
diff --git a/problems/partition-array-into-three-parts-with-equal-sum/README.md b/problems/partition-array-into-three-parts-with-equal-sum/README.md
deleted file mode 100644
index 2acd962bb..000000000
--- a/problems/partition-array-into-three-parts-with-equal-sum/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../numbers-with-repeated-digits "Numbers With Repeated Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../best-sightseeing-pair "Best Sightseeing Pair")
-
-## [1013. Partition Array Into Three Parts With Equal Sum (Easy)](https://leetcode.com/problems/partition-array-into-three-parts-with-equal-sum "将数组分成和相等的三个部分")
-
-<p>Given an array of integers <code>arr</code>, return <code>true</code> if we can partition the array into three <strong>non-empty</strong> parts with equal sums.</p>
-
-<p>Formally, we can partition the array if we can find indexes <code>i + 1 &lt; j</code> with <code>(arr[0] + arr[1] + ... + arr[i] == arr[i + 1] + arr[i + 2] + ... + arr[j - 1] == arr[j] + arr[j + 1] + ... + arr[arr.length - 1])</code></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [0,2,1,-6,6,-7,9,1,2,0,1]
-<strong>Output:</strong> true
-<strong>Explanation: </strong>0 + 2 + 1 = -6 + 6 - 7 + 9 + 1 = 2 + 0 + 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [0,2,1,-6,6,7,9,-1,2,0,1]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,3,6,5,-2,2,5,1,-9,4]
-<strong>Output:</strong> true
-<strong>Explanation: </strong>3 + 3 = 6 = 5 - 2 + 2 + 5 + 1 - 9 + 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= arr.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= arr[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If we have three parts with the same sum, what is the sum of each?
-If you can find the first part, can you find the second part?
-</details>
diff --git a/problems/partition-array-into-three-parts-with-equal-sum/partition_array_into_three_parts_with_equal_sum.go b/problems/partition-array-into-three-parts-with-equal-sum/partition_array_into_three_parts_with_equal_sum.go
deleted file mode 100644
index 7e7b08762..000000000
--- a/problems/partition-array-into-three-parts-with-equal-sum/partition_array_into_three_parts_with_equal_sum.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem1013
-
-func canThreePartsEqualSum(A []int) bool {
-	avg, sum := 0, 0
-	for _, v := range A {
-		sum += v
-	}
-	if sum%3 != 0 {
-		return false
-	}
-	avg, sum, count := sum/3, 0, 0
-	for _, v := range A {
-		sum += v
-		if sum == avg {
-			count, sum = count+1, 0
-		}
-	}
-	return count == 3
-}
diff --git a/problems/partition-array-into-three-parts-with-equal-sum/partition_array_into_three_parts_with_equal_sum_test.go b/problems/partition-array-into-three-parts-with-equal-sum/partition_array_into_three_parts_with_equal_sum_test.go
deleted file mode 100644
index ff9546982..000000000
--- a/problems/partition-array-into-three-parts-with-equal-sum/partition_array_into_three_parts_with_equal_sum_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem1013
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestCanThreePartsEqualSum(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{0, 2, 1, -6, 6, -7, 9, 1, 2, 0, 1},
-			want: true,
-		},
-		{
-			in:   []int{0, 2, 1, -6, 6, 7, 9, -1, 2, 0, 1},
-			want: false,
-		},
-		{
-			in:   []int{3, 3, 6, 5, -2, 2, 5, 1, -9, 4},
-			want: true,
-		},
-		{
-			in:   []int{-3, 3, 3, -3},
-			want: false,
-		},
-		{
-			in:   []int{1, 7, 2, 6, 3, 5, 8},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := canThreePartsEqualSum(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/partition-array-into-two-arrays-to-minimize-sum-difference/README.md b/problems/partition-array-into-two-arrays-to-minimize-sum-difference/README.md
deleted file mode 100644
index 2869b4b0e..000000000
--- a/problems/partition-array-into-two-arrays-to-minimize-sum-difference/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stock-price-fluctuation "Stock Price Fluctuation ")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-alternating-subarray-sum "Maximum Alternating Subarray Sum")
-
-## [2035. Partition Array Into Two Arrays to Minimize Sum Difference (Hard)](https://leetcode.com/problems/partition-array-into-two-arrays-to-minimize-sum-difference "将数组分成两个数组并最小化数组和的差")
-
-<p>You are given an integer array <code>nums</code> of <code>2 * n</code> integers. You need to partition <code>nums</code> into <strong>two</strong> arrays of length <code>n</code> to <strong>minimize the absolute difference</strong> of the <strong>sums</strong> of the arrays. To partition <code>nums</code>, put each element of <code>nums</code> into <strong>one</strong> of the two arrays.</p>
-
-<p>Return <em>the <strong>minimum</strong> possible absolute difference</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="example-1" src="https://assets.leetcode.com/uploads/2021/10/02/ex1.png" style="width: 240px; height: 106px;" />
-<pre>
-<strong>Input:</strong> nums = [3,9,7,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> One optimal partition is: [3,9] and [7,3].
-The absolute difference between the sums of the arrays is abs((3 + 9) - (7 + 3)) = 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-36,36]
-<strong>Output:</strong> 72
-<strong>Explanation:</strong> One optimal partition is: [-36] and [36].
-The absolute difference between the sums of the arrays is abs((-36) - (36)) = 72.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="example-3" src="https://assets.leetcode.com/uploads/2021/10/02/ex3.png" style="width: 316px; height: 106px;" />
-<pre>
-<strong>Input:</strong> nums = [2,-1,0,4,-2,-9]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> One optimal partition is: [2,4,-9] and [-1,0,-2].
-The absolute difference between the sums of the arrays is abs((2 + 4 + -9) - (-1 + 0 + -2)) = 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 15</code></li>
-	<li><code>nums.length == 2 * n</code></li>
-	<li><code>-10<sup>7</sup> &lt;= nums[i] &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The target sum for the two partitions is sum(nums) / 2.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Could you reduce the time complexity if you arbitrarily divide nums into two halves (two arrays)? Meet-in-the-Middle?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For both halves, pre-calculate a 2D array where the kth index will store all possible sum values if only k elements from this half are added.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For each sum of k elements in the first half, find the best sum of n-k elements in the second half such that the two sums add up to a value closest to the target sum from hint 1. These two subsets will form one array of the partition.
-</details>
diff --git a/problems/partition-equal-subset-sum/README.md b/problems/partition-equal-subset-sum/README.md
deleted file mode 100644
index 691f51958..000000000
--- a/problems/partition-equal-subset-sum/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-strings "Add Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../pacific-atlantic-water-flow "Pacific Atlantic Water Flow")
-
-## [416. Partition Equal Subset Sum (Medium)](https://leetcode.com/problems/partition-equal-subset-sum "分割等和子集")
-
-<p>Given a <strong>non-empty</strong> array <code>nums</code> containing <strong>only positive integers</strong>, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5,11,5]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The array can be partitioned as [1, 5, 5] and [11].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,5]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The array cannot be partitioned into equal sum subsets.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 200</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Partition to K Equal Sum Subsets](../partition-to-k-equal-sum-subsets) (Medium)
diff --git a/problems/partition-equal-subset-sum/partition_equal_subset_sum.go b/problems/partition-equal-subset-sum/partition_equal_subset_sum.go
deleted file mode 100644
index 0ed830b00..000000000
--- a/problems/partition-equal-subset-sum/partition_equal_subset_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem416
diff --git a/problems/partition-equal-subset-sum/partition_equal_subset_sum_test.go b/problems/partition-equal-subset-sum/partition_equal_subset_sum_test.go
deleted file mode 100644
index 0ed830b00..000000000
--- a/problems/partition-equal-subset-sum/partition_equal_subset_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem416
diff --git a/problems/partition-labels/README.md b/problems/partition-labels/README.md
deleted file mode 100644
index 760ae0cf3..000000000
--- a/problems/partition-labels/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../prime-number-of-set-bits-in-binary-representation "Prime Number of Set Bits in Binary Representation")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-plus-sign "Largest Plus Sign")
-
-## [763. Partition Labels (Medium)](https://leetcode.com/problems/partition-labels "划分字母区间")
-
-<p>You are given a string <code>s</code>. We want to partition the string into as many parts as possible so that each letter appears in at most one part.</p>
-
-<p>Return <em>a list of integers representing the size of these parts</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ababcbacadefegdehijhklij&quot;
-<strong>Output:</strong> [9,7,8]
-<strong>Explanation:</strong>
-The partition is &quot;ababcbaca&quot;, &quot;defegde&quot;, &quot;hijhklij&quot;.
-This is a partition so that each letter appears in at most one part.
-A partition like &quot;ababcbacadefegde&quot;, &quot;hijhklij&quot; is incorrect, because it splits s into less parts.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;eccbbbbdec&quot;
-<strong>Output:</strong> [10]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 500</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Merge Intervals](../merge-intervals) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to greedily choose the smallest partition that includes the first letter.  If you have something like "abaccbdeffed", then you might need to add b.  You can use an map like "last['b'] = 5" to help you expand the width of your partition.
-</details>
diff --git a/problems/partition-labels/partition_labels.go b/problems/partition-labels/partition_labels.go
deleted file mode 100644
index 09f8f05ae..000000000
--- a/problems/partition-labels/partition_labels.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem763
diff --git a/problems/partition-labels/partition_labels_test.go b/problems/partition-labels/partition_labels_test.go
deleted file mode 100644
index 09f8f05ae..000000000
--- a/problems/partition-labels/partition_labels_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem763
diff --git a/problems/partition-list/README.md b/problems/partition-list/README.md
deleted file mode 100644
index e212ee33c..000000000
--- a/problems/partition-list/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximal-rectangle "Maximal Rectangle")
-　　　　　　　　　　　　　　　　
-[Next >](../scramble-string "Scramble String")
-
-## [86. Partition List (Medium)](https://leetcode.com/problems/partition-list "分隔链表")
-
-<p>Given the <code>head</code> of a linked list and a value <code>x</code>, partition it such that all nodes <strong>less than</strong> <code>x</code> come before nodes <strong>greater than or equal</strong> to <code>x</code>.</p>
-
-<p>You should <strong>preserve</strong> the original relative order of the nodes in each of the two partitions.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/partition.jpg" style="width: 662px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,4,3,2,5,2], x = 3
-<strong>Output:</strong> [1,2,2,4,3,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [2,1], x = 2
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[0, 200]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-	<li><code>-200 &lt;= x &lt;= 200</code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
diff --git a/problems/partition-list/partition_list.go b/problems/partition-list/partition_list.go
deleted file mode 100644
index 6c238a137..000000000
--- a/problems/partition-list/partition_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem86
diff --git a/problems/partition-list/partition_list_test.go b/problems/partition-list/partition_list_test.go
deleted file mode 100644
index 6c238a137..000000000
--- a/problems/partition-list/partition_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem86
diff --git a/problems/partition-to-k-equal-sum-subsets/README.md b/problems/partition-to-k-equal-sum-subsets/README.md
deleted file mode 100644
index 3d047fd41..000000000
--- a/problems/partition-to-k-equal-sum-subsets/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../degree-of-an-array "Degree of an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../falling-squares "Falling Squares")
-
-## [698. Partition to K Equal Sum Subsets (Medium)](https://leetcode.com/problems/partition-to-k-equal-sum-subsets "划分为k个相等的子集")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <code>true</code> if it is possible to divide this array into <code>k</code> non-empty subsets whose sums are all equal.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,3,2,3,5,2,1], k = 4
-<strong>Output:</strong> true
-<strong>Explanation:</strong> It&#39;s possible to divide it into 4 subsets (5), (1, 4), (2,3), (2,3) with equal sums.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4], k = 3
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= nums.length &lt;= 16</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li>The frequency of each element is in the range <code>[1, 4]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Similar Questions
-  1. [Partition Equal Subset Sum](../partition-equal-subset-sum) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can figure out what target each subset must sum to.  Then, let's recursively search, where at each call to our function, we choose which of k subsets the next value will join.
-</details>
diff --git a/problems/partition-to-k-equal-sum-subsets/partition_to_k_equal_sum_subsets.go b/problems/partition-to-k-equal-sum-subsets/partition_to_k_equal_sum_subsets.go
deleted file mode 100644
index 8508b90d5..000000000
--- a/problems/partition-to-k-equal-sum-subsets/partition_to_k_equal_sum_subsets.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem698
diff --git a/problems/partition-to-k-equal-sum-subsets/partition_to_k_equal_sum_subsets_test.go b/problems/partition-to-k-equal-sum-subsets/partition_to_k_equal_sum_subsets_test.go
deleted file mode 100644
index 8508b90d5..000000000
--- a/problems/partition-to-k-equal-sum-subsets/partition_to_k_equal_sum_subsets_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem698
diff --git a/problems/partitioning-into-minimum-number-of-deci-binary-numbers/README.md b/problems/partitioning-into-minimum-number-of-deci-binary-numbers/README.md
deleted file mode 100644
index 3b62f1968..000000000
--- a/problems/partitioning-into-minimum-number-of-deci-binary-numbers/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-of-matches-in-tournament "Count of Matches in Tournament")
-　　　　　　　　　　　　　　　　
-[Next >](../stone-game-vii "Stone Game VII")
-
-## [1689. Partitioning Into Minimum Number Of Deci-Binary Numbers (Medium)](https://leetcode.com/problems/partitioning-into-minimum-number-of-deci-binary-numbers "十-二进制数的最少数目")
-
-<p>A decimal number is called <strong>deci-binary</strong> if each of its digits is either <code>0</code> or <code>1</code> without any leading zeros. For example, <code>101</code> and <code>1100</code> are <strong>deci-binary</strong>, while <code>112</code> and <code>3001</code> are not.</p>
-
-<p>Given a string <code>n</code> that represents a positive decimal integer, return <em>the <strong>minimum</strong> number of positive <strong>deci-binary</strong> numbers needed so that they sum up to </em><code>n</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;32&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 10 + 11 + 11 = 32
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;82734&quot;
-<strong>Output:</strong> 8
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;27346209830709182346&quot;
-<strong>Output:</strong> 9
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>n</code> consists of only digits.</li>
-	<li><code>n</code> does not contain any leading zeros and represents a positive integer.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think about if the input was only one digit. Then you need to add up as many ones as the value of this digit.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the input has multiple digits, then you can solve for each digit independently, and merge the answers to form numbers that add up to that input.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Thus the answer is equal to the max digit.
-</details>
diff --git a/problems/pascals-triangle-ii/README.md b/problems/pascals-triangle-ii/README.md
deleted file mode 100644
index 8817e0ce5..000000000
--- a/problems/pascals-triangle-ii/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pascals-triangle "Pascal's Triangle")
-　　　　　　　　　　　　　　　　
-[Next >](../triangle "Triangle")
-
-## [119. Pascal's Triangle II (Easy)](https://leetcode.com/problems/pascals-triangle-ii "杨辉三角 II")
-
-<p>Given an integer <code>rowIndex</code>, return the <code>rowIndex<sup>th</sup></code> (<strong>0-indexed</strong>) row of the <strong>Pascal&#39;s triangle</strong>.</p>
-
-<p>In <strong>Pascal&#39;s triangle</strong>, each number is the sum of the two numbers directly above it as shown:</p>
-<img alt="" src="https://upload.wikimedia.org/wikipedia/commons/0/0d/PascalTriangleAnimated2.gif" style="height:240px; width:260px" />
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> rowIndex = 3
-<strong>Output:</strong> [1,3,3,1]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> rowIndex = 0
-<strong>Output:</strong> [1]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> rowIndex = 1
-<strong>Output:</strong> [1,1]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= rowIndex &lt;= 33</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you optimize your algorithm to use only <code>O(rowIndex)</code> extra space?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Pascal's Triangle](../pascals-triangle) (Easy)
diff --git a/problems/pascals-triangle-ii/pascals_triangle_ii.go b/problems/pascals-triangle-ii/pascals_triangle_ii.go
deleted file mode 100644
index 6e95883bb..000000000
--- a/problems/pascals-triangle-ii/pascals_triangle_ii.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem119
-
-func getRow(rowIndex int) []int {
-	row := make([]int, rowIndex+1)
-	row[0], row[rowIndex] = 1, 1
-	for i := 1; i < rowIndex; i++ {
-		row[i] = row[i-1] * (rowIndex - i + 1) / i
-	}
-	return row
-}
diff --git a/problems/pascals-triangle-ii/pascals_triangle_ii_test.go b/problems/pascals-triangle-ii/pascals_triangle_ii_test.go
deleted file mode 100644
index 1e39cb1eb..000000000
--- a/problems/pascals-triangle-ii/pascals_triangle_ii_test.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package problem119
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   int
-	want []int
-}
-
-func TestGetRow(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   2,
-			want: []int{1, 2, 1},
-		},
-		{
-			in:   3,
-			want: []int{1, 3, 3, 1},
-		},
-		{
-			in:   5,
-			want: []int{1, 5, 10, 10, 5, 1},
-		},
-	}
-	for _, tt := range tests {
-		got := getRow(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/pascals-triangle/README.md b/problems/pascals-triangle/README.md
deleted file mode 100644
index 26b59095c..000000000
--- a/problems/pascals-triangle/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../populating-next-right-pointers-in-each-node-ii "Populating Next Right Pointers in Each Node II")
-　　　　　　　　　　　　　　　　
-[Next >](../pascals-triangle-ii "Pascal's Triangle II")
-
-## [118. Pascal's Triangle (Easy)](https://leetcode.com/problems/pascals-triangle "杨辉三角")
-
-<p>Given an integer <code>numRows</code>, return the first numRows of <strong>Pascal&#39;s triangle</strong>.</p>
-
-<p>In <strong>Pascal&#39;s triangle</strong>, each number is the sum of the two numbers directly above it as shown:</p>
-<img alt="" src="https://upload.wikimedia.org/wikipedia/commons/0/0d/PascalTriangleAnimated2.gif" style="height:240px; width:260px" />
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> numRows = 5
-<strong>Output:</strong> [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> numRows = 1
-<strong>Output:</strong> [[1]]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= numRows &lt;= 30</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Pascal's Triangle II](../pascals-triangle-ii) (Easy)
diff --git a/problems/pascals-triangle/pascals_triangle.go b/problems/pascals-triangle/pascals_triangle.go
deleted file mode 100644
index 5f050843d..000000000
--- a/problems/pascals-triangle/pascals_triangle.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem118
-
-func generate(numRows int) [][]int {
-	ans := make([][]int, numRows)
-	for i := 0; i < numRows; i++ {
-		row := make([]int, i+1)
-		row[0], row[i] = 1, 1
-		for j := 1; j < i; j++ {
-			row[j] = ans[i-1][j-1] + ans[i-1][j]
-		}
-		ans[i] = row
-	}
-	return ans
-}
diff --git a/problems/pascals-triangle/pascals_triangle_test.go b/problems/pascals-triangle/pascals_triangle_test.go
deleted file mode 100644
index 7dc90f988..000000000
--- a/problems/pascals-triangle/pascals_triangle_test.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package problem118
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   int
-	want [][]int
-}
-
-func TestGenerate(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: 5,
-			want: [][]int{
-				{1},
-				{1, 1},
-				{1, 2, 1},
-				{1, 3, 3, 1},
-				{1, 4, 6, 4, 1},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := generate(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/patching-array/README.md b/problems/patching-array/README.md
deleted file mode 100644
index 8bc118c52..000000000
--- a/problems/patching-array/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-increasing-path-in-a-matrix "Longest Increasing Path in a Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../verify-preorder-serialization-of-a-binary-tree "Verify Preorder Serialization of a Binary Tree")
-
-## [330. Patching Array (Hard)](https://leetcode.com/problems/patching-array "按要求补齐数组")
-
-<p>Given a sorted integer array <code>nums</code> and an integer <code>n</code>, add/patch elements to the array such that any number in the range <code>[1, n]</code> inclusive can be formed by the sum of some elements in the array.</p>
-
-<p>Return <em>the minimum number of patches required</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3], n = 6
-<strong>Output:</strong> 1
-Explanation:
-Combinations of nums are [1], [3], [1,3], which form possible sums of: 1, 3, 4.
-Now if we add/patch 2 to nums, the combinations are: [1], [2], [3], [1,3], [2,3], [1,2,3].
-Possible sums are 1, 2, 3, 4, 5, 6, which now covers the range [1, 6].
-So we only need 1 patch.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5,10], n = 20
-<strong>Output:</strong> 2
-Explanation: The two patches can be [2, 4].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,2], n = 5
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>nums</code> is sorted in <strong>ascending order</strong>.</li>
-	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
diff --git a/problems/patching-array/patching_array.go b/problems/patching-array/patching_array.go
deleted file mode 100644
index 129bf58b2..000000000
--- a/problems/patching-array/patching_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem330
diff --git a/problems/patching-array/patching_array_test.go b/problems/patching-array/patching_array_test.go
deleted file mode 100644
index 129bf58b2..000000000
--- a/problems/patching-array/patching_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem330
diff --git a/problems/path-crossing/README.md b/problems/path-crossing/README.md
deleted file mode 100644
index 5c59e8448..000000000
--- a/problems/path-crossing/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../friendly-movies-streamed-last-month "Friendly Movies Streamed Last Month")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-array-pairs-are-divisible-by-k "Check If Array Pairs Are Divisible by k")
-
-## [1496. Path Crossing (Easy)](https://leetcode.com/problems/path-crossing "判断路径是否相交")
-
-<p>Given a string <code>path</code>, where <code>path[i] = &#39;N&#39;</code>, <code>&#39;S&#39;</code>, <code>&#39;E&#39;</code> or <code>&#39;W&#39;</code>, each representing moving one unit north, south, east, or west, respectively. You start at the origin <code>(0, 0)</code> on a 2D plane and walk on the path specified by <code>path</code>.</p>
-
-<p>Return <code>true</code> <em>if the path crosses itself at any point, that is, if at any time you are on a location you have previously visited</em>. Return <code>false</code> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/10/screen-shot-2020-06-10-at-123929-pm.png" style="width: 400px; height: 358px;" />
-<pre>
-<strong>Input:</strong> path = &quot;NES&quot;
-<strong>Output:</strong> false 
-<strong>Explanation:</strong> Notice that the path doesn&#39;t cross any point more than once.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/06/10/screen-shot-2020-06-10-at-123843-pm.png" style="width: 400px; height: 339px;" />
-<pre>
-<strong>Input:</strong> path = &quot;NESWW&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Notice that the path visits the origin twice.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= path.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>path[i]</code> is either <code>&#39;N&#39;</code>, <code>&#39;S&#39;</code>, <code>&#39;E&#39;</code>, or <code>&#39;W&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process while keeping track of visited points.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a set to store previously visited points.
-</details>
diff --git a/problems/path-in-zigzag-labelled-binary-tree/README.md b/problems/path-in-zigzag-labelled-binary-tree/README.md
deleted file mode 100644
index 32eb5c01b..000000000
--- a/problems/path-in-zigzag-labelled-binary-tree/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distribute-candies-to-people "Distribute Candies to People")
-　　　　　　　　　　　　　　　　
-[Next >](../filling-bookcase-shelves "Filling Bookcase Shelves")
-
-## [1104. Path In Zigzag Labelled Binary Tree (Medium)](https://leetcode.com/problems/path-in-zigzag-labelled-binary-tree "二叉树寻路")
-
-<p>In an infinite binary tree where every node has two children, the nodes are labelled in row order.</p>
-
-<p>In the odd numbered rows (ie., the first, third, fifth,...), the labelling is left to right, while in the even numbered rows (second, fourth, sixth,...), the labelling is right to left.</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/06/24/tree.png" style="width: 300px; height: 138px;" /></p>
-
-<p>Given the <code>label</code> of a node in this tree, return the labels in the path from the root of the tree to the&nbsp;node with that <code>label</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> label = 14
-<strong>Output:</strong> [1,3,4,14]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> label = 26
-<strong>Output:</strong> [1,2,6,10,26]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= label &lt;= 10^6</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Based on the label of the current node, find what the label must be for the parent of that node.
-</details>
diff --git a/problems/path-in-zigzag-labelled-binary-tree/path_in_zigzag_labelled_binary_tree.go b/problems/path-in-zigzag-labelled-binary-tree/path_in_zigzag_labelled_binary_tree.go
deleted file mode 100644
index eff4b25ad..000000000
--- a/problems/path-in-zigzag-labelled-binary-tree/path_in_zigzag_labelled_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1104
diff --git a/problems/path-sum-ii/README.md b/problems/path-sum-ii/README.md
deleted file mode 100644
index 50e88d874..000000000
--- a/problems/path-sum-ii/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-sum "Path Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../flatten-binary-tree-to-linked-list "Flatten Binary Tree to Linked List")
-
-## [113. Path Sum II (Medium)](https://leetcode.com/problems/path-sum-ii "路径总和 II")
-
-<p>Given the <code>root</code> of a binary tree and an integer <code>targetSum</code>, return <em>all <strong>root-to-leaf</strong> paths where the sum of the node values in the path equals </em><code>targetSum</code><em>. Each path should be returned as a list of the node <strong>values</strong>, not node references</em>.</p>
-
-<p>A <strong>root-to-leaf</strong> path is a path starting from the root and ending at any leaf node. A <strong>leaf</strong> is a node with no children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/pathsumii1.jpg" style="width: 500px; height: 356px;" />
-<pre>
-<strong>Input:</strong> root = [5,4,8,11,null,13,4,7,2,null,null,5,1], targetSum = 22
-<strong>Output:</strong> [[5,4,11,2],[5,8,4,5]]
-<strong>Explanation:</strong> There are two paths whose sum equals targetSum:
-5 + 4 + 11 + 2 = 22
-5 + 8 + 4 + 5 = 22
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/pathsum2.jpg" style="width: 212px; height: 181px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3], targetSum = 5
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,2], targetSum = 0
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 5000]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-	<li><code>-1000 &lt;= targetSum &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Path Sum](../path-sum) (Easy)
-  1. [Binary Tree Paths](../binary-tree-paths) (Easy)
-  1. [Path Sum III](../path-sum-iii) (Medium)
-  1. [Path Sum IV](../path-sum-iv) (Medium)
diff --git a/problems/path-sum-ii/path_sum_ii.go b/problems/path-sum-ii/path_sum_ii.go
deleted file mode 100644
index b4aada243..000000000
--- a/problems/path-sum-ii/path_sum_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem113
diff --git a/problems/path-sum-ii/path_sum_ii_test.go b/problems/path-sum-ii/path_sum_ii_test.go
deleted file mode 100644
index b4aada243..000000000
--- a/problems/path-sum-ii/path_sum_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem113
diff --git a/problems/path-sum-iii/README.md b/problems/path-sum-iii/README.md
deleted file mode 100644
index 88f5690c5..000000000
--- a/problems/path-sum-iii/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-right-interval "Find Right Interval")
-　　　　　　　　　　　　　　　　
-[Next >](../find-all-anagrams-in-a-string "Find All Anagrams in a String")
-
-## [437. Path Sum III (Medium)](https://leetcode.com/problems/path-sum-iii "路径总和 III")
-
-<p>Given the <code>root</code> of a binary tree and an integer <code>targetSum</code>, return <em>the number of paths where the sum of the values&nbsp;along the path equals</em>&nbsp;<code>targetSum</code>.</p>
-
-<p>The path does not need to start or end at the root or a leaf, but it must go downwards (i.e., traveling only from parent nodes to child nodes).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/09/pathsum3-1-tree.jpg" style="width: 450px; height: 386px;" />
-<pre>
-<strong>Input:</strong> root = [10,5,-3,3,2,null,11,3,-2,null,1], targetSum = 8
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The paths that sum to 8 are shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [5,4,8,11,null,13,4,7,2,null,null,5,1], targetSum = 22
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 1000]</code>.</li>
-	<li><code>-10<sup>9</sup> &lt;= Node.val &lt;= 10<sup>9</sup></code></li>
-	<li><code>-1000 &lt;= targetSum &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Path Sum](../path-sum) (Easy)
-  1. [Path Sum II](../path-sum-ii) (Medium)
-  1. [Path Sum IV](../path-sum-iv) (Medium)
-  1. [Longest Univalue Path](../longest-univalue-path) (Medium)
diff --git a/problems/path-sum-iii/path_sum_iii.go b/problems/path-sum-iii/path_sum_iii.go
deleted file mode 100644
index c096c6c56..000000000
--- a/problems/path-sum-iii/path_sum_iii.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem437
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func pathSum(root *TreeNode, sum int) int {
-	if root == nil {
-		return 0
-	}
-	return findPath(root, sum) + pathSum(root.Left, sum) + pathSum(root.Right, sum)
-}
-
-func findPath(root *TreeNode, sum int) int {
-	r := 0
-	if root == nil {
-		return 0
-	} else if root.Val == sum {
-		r++
-	}
-	r += findPath(root.Left, sum-root.Val)
-	r += findPath(root.Right, sum-root.Val)
-	return r
-}
diff --git a/problems/path-sum-iii/path_sum_iii_test.go b/problems/path-sum-iii/path_sum_iii_test.go
deleted file mode 100644
index 63bfddee1..000000000
--- a/problems/path-sum-iii/path_sum_iii_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem437
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	sum  int
-	want int
-}
-
-func TestPathSum(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{10, 5, -3, 3, 2, kit.NULL, 11, 3, -2, kit.NULL, 1},
-			sum:  8,
-			want: 3,
-		},
-	}
-	for _, tt := range tests {
-		root := kit.SliceInt2TreeNode(tt.in)
-		got := pathSum(root, tt.sum)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/path-sum-iv/README.md b/problems/path-sum-iv/README.md
deleted file mode 100644
index d0052c494..000000000
--- a/problems/path-sum-iv/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../non-decreasing-array "Non-decreasing Array")
-　　　　　　　　　　　　　　　　
-[Next >](../beautiful-arrangement-ii "Beautiful Arrangement II")
-
-## [666. Path Sum IV (Medium)](https://leetcode.com/problems/path-sum-iv "路径总和 IV")
-
-<p>If the depth of a tree is smaller than <code>5</code>, then this tree can be represented by a list of three-digits integers.</p>
-
-<p>For each integer in this list:</p>
-
-<ol>
-	<li>The hundreds digit represents the depth <code>D</code> of this node, <code>1 &lt;= D &lt;= 4.</code></li>
-	<li>The tens digit represents the position <code>P</code> of this node in the level it belongs to, <code>1 &lt;= P &lt;= 8</code>. The position is the same as that in a full binary tree.</li>
-	<li>The units digit represents the value <code>V</code> of this node, <code>0 &lt;= V &lt;= 9.</code></li>
-</ol>
-
-<p>&nbsp;</p>
-
-<p>Given a list of <code>ascending</code> three-digits integers representing a binary tree with the depth smaller than 5, you need to return the sum of all paths from the root towards the leaves.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre><b>Input:</b> [113, 215, 221]
-<b>Output:</b> 12
-<b>Explanation:</b> 
-The tree that the list represents is:
-    3
-   / \
-  5   1
-
-The path sum is (3 + 5) + (3 + 1) = 12.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Example 2:</b></p>
-
-<pre><b>Input:</b> [113, 221]
-<b>Output:</b> 4
-<b>Explanation:</b> 
-The tree that the list represents is: 
-    3
-     \
-      1
-
-The path sum is (3 + 1) = 4.
-</pre>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Path Sum](../path-sum) (Easy)
-  1. [Path Sum II](../path-sum-ii) (Medium)
-  1. [Binary Tree Maximum Path Sum](../binary-tree-maximum-path-sum) (Hard)
-  1. [Path Sum III](../path-sum-iii) (Medium)
diff --git a/problems/path-sum-iv/path_sum_iv.go b/problems/path-sum-iv/path_sum_iv.go
deleted file mode 100644
index 31046a05c..000000000
--- a/problems/path-sum-iv/path_sum_iv.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem666
diff --git a/problems/path-sum-iv/path_sum_iv_test.go b/problems/path-sum-iv/path_sum_iv_test.go
deleted file mode 100644
index 31046a05c..000000000
--- a/problems/path-sum-iv/path_sum_iv_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem666
diff --git a/problems/path-sum/README.md b/problems/path-sum/README.md
deleted file mode 100644
index 71194c380..000000000
--- a/problems/path-sum/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-depth-of-binary-tree "Minimum Depth of Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../path-sum-ii "Path Sum II")
-
-## [112. Path Sum (Easy)](https://leetcode.com/problems/path-sum "路径总和")
-
-<p>Given the <code>root</code> of a binary tree and an integer <code>targetSum</code>, return <code>true</code> if the tree has a <strong>root-to-leaf</strong> path such that adding up all the values along the path equals <code>targetSum</code>.</p>
-
-<p>A <strong>leaf</strong> is a node with no children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/pathsum1.jpg" style="width: 500px; height: 356px;" />
-<pre>
-<strong>Input:</strong> root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The root-to-leaf path with the target sum is shown.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/pathsum2.jpg" />
-<pre>
-<strong>Input:</strong> root = [1,2,3], targetSum = 5
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There two root-to-leaf paths in the tree:
-(1 --&gt; 2): The sum is 3.
-(1 --&gt; 3): The sum is 4.
-There is no root-to-leaf path with sum = 5.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [], targetSum = 0
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Since the tree is empty, there are no root-to-leaf paths.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 5000]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-	<li><code>-1000 &lt;= targetSum &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Path Sum II](../path-sum-ii) (Medium)
-  1. [Binary Tree Maximum Path Sum](../binary-tree-maximum-path-sum) (Hard)
-  1. [Sum Root to Leaf Numbers](../sum-root-to-leaf-numbers) (Medium)
-  1. [Path Sum III](../path-sum-iii) (Medium)
-  1. [Path Sum IV](../path-sum-iv) (Medium)
diff --git a/problems/path-sum/path_sum.go b/problems/path-sum/path_sum.go
deleted file mode 100644
index a8e044bda..000000000
--- a/problems/path-sum/path_sum.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package problem112
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func hasPathSum(root *TreeNode, sum int) bool {
-	if root == nil {
-		return false
-	}
-	if root.Left == nil && root.Right == nil {
-		return root.Val == sum
-	}
-	return hasPathSum(root.Left, sum-root.Val) || hasPathSum(root.Right, sum-root.Val)
-}
diff --git a/problems/path-sum/path_sum_test.go b/problems/path-sum/path_sum_test.go
deleted file mode 100644
index 93325f6fd..000000000
--- a/problems/path-sum/path_sum_test.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package problem112
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	sum  int
-	want bool
-}
-
-func TestHasPathSum(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{5, 4, 8, 11, kit.NULL, 13, 4, 7, 2, kit.NULL, kit.NULL, kit.NULL, 1},
-			sum:  22,
-			want: true,
-		},
-		{
-			in:   []int{5, 8, 4, 4, 13, kit.NULL, 11, 7, 2},
-			sum:  22,
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := hasPathSum(kit.SliceInt2TreeNode(tt.in), tt.sum)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/path-with-maximum-gold/README.md b/problems/path-with-maximum-gold/README.md
deleted file mode 100644
index 7b86e75cc..000000000
--- a/problems/path-with-maximum-gold/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-arithmetic-subsequence-of-given-difference "Longest Arithmetic Subsequence of Given Difference")
-　　　　　　　　　　　　　　　　
-[Next >](../count-vowels-permutation "Count Vowels Permutation")
-
-## [1219. Path with Maximum Gold (Medium)](https://leetcode.com/problems/path-with-maximum-gold "黄金矿工")
-
-<p>In a gold mine <code>grid</code> of size <code>m x n</code>, each cell in this mine has an integer representing the amount of gold in that cell, <code>0</code> if it is empty.</p>
-
-<p>Return the maximum amount of gold you can collect under the conditions:</p>
-
-<ul>
-	<li>Every time you are located in a cell you will collect all the gold in that cell.</li>
-	<li>From your position, you can walk one step to the left, right, up, or down.</li>
-	<li>You can&#39;t visit the same cell more than once.</li>
-	<li>Never visit a cell with <code>0</code> gold.</li>
-	<li>You can start and stop collecting gold from <strong>any </strong>position in the grid that has some gold.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0,6,0],[5,8,7],[0,9,0]]
-<strong>Output:</strong> 24
-<strong>Explanation:</strong>
-[[0,6,0],
- [5,8,7],
- [0,9,0]]
-Path to get the maximum gold, 9 -&gt; 8 -&gt; 7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,0,7],[2,0,6],[3,4,5],[0,3,0],[9,0,20]]
-<strong>Output:</strong> 28
-<strong>Explanation:</strong>
-[[1,0,7],
- [2,0,6],
- [3,4,5],
- [0,3,0],
- [9,0,20]]
-Path to get the maximum gold, 1 -&gt; 2 -&gt; 3 -&gt; 4 -&gt; 5 -&gt; 6 -&gt; 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 15</code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;= 100</code></li>
-	<li>There are at most <strong>25 </strong>cells containing gold.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use recursion to try all such paths and find the one with the maximum value.
-</details>
diff --git a/problems/path-with-maximum-minimum-value/README.md b/problems/path-with-maximum-minimum-value/README.md
deleted file mode 100644
index 023f25b3f..000000000
--- a/problems/path-with-maximum-minimum-value/README.md
+++ /dev/null
@@ -1,90 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-earliest-moment-when-everyone-become-friends "The Earliest Moment When Everyone Become Friends")
-　　　　　　　　　　　　　　　　
-[Next >](../distribute-candies-to-people "Distribute Candies to People")
-
-## [1102. Path With Maximum Minimum Value (Medium)](https://leetcode.com/problems/path-with-maximum-minimum-value "得分最高的路径")
-
-<p>Given a&nbsp;matrix of integers <code>A</code>&nbsp;with&nbsp;<font face="monospace">R</font>&nbsp;rows and <font face="monospace">C</font>&nbsp;columns, find&nbsp;the <strong>maximum</strong>&nbsp;score&nbsp;of a path starting at&nbsp;<code>[0,0]</code>&nbsp;and ending at <code>[R-1,C-1]</code>.</p>
-
-<p>The <em>score</em> of a path is the <strong>minimum</strong> value in that path.&nbsp; For example, the value of the path 8 &rarr;&nbsp; 4 &rarr;&nbsp; 5 &rarr;&nbsp; 9 is 4.</p>
-
-<p>A <em>path</em> moves some number of times from one visited cell to any neighbouring unvisited cell in one of the 4 cardinal directions (north, east, west, south).</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/04/23/1313_ex1.JPG" style="width: 70px; height: 59px;" /></strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[[5,4,5],[1,2,6],[7,4,6]]</span>
-<strong>Output: </strong><span id="example-output-1">4</span>
-<strong>Explanation: </strong>
-The path with the maximum score is highlighted in yellow. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/04/23/1313_ex2.JPG" style="width: 134px; height: 39px;" /></strong></p>
-
-<pre>
-<strong>Input: </strong><span>[[2,2,1,2,2,2],[1,2,2,2,1,2]]</span>
-<strong>Output: 2</strong></pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/04/23/1313_ex3.JPG" /></strong></p>
-
-<pre>
-<strong>Input: </strong><span>[[3,4,6,3,4],[0,2,1,1,7],[8,8,3,2,7],[3,2,4,9,8],[4,1,2,0,0],[4,6,5,4,3]]</span>
-<strong>Output: 3</strong></pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= R, C&nbsp;&lt;= 100</code></li>
-	<li><code>0 &lt;= A[i][j] &lt;= 10^9</code></li>
-</ol>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if we sort each cell of the matrix by the value?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Don't include small values in your path if you can only include large values.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Let's keep adding a possible cell to use in the path incrementally with decreasing values.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-If the start and end cells are connected then we don't need to add more cells.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Use union-find data structure to check connectivity and return as answer the value of the given cell that makes start and end cells connected.
-</details>
diff --git a/problems/path-with-maximum-probability/README.md b/problems/path-with-maximum-probability/README.md
deleted file mode 100644
index 8a74476a7..000000000
--- a/problems/path-with-maximum-probability/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-substrings-with-only-1s "Number of Substrings With Only 1s")
-　　　　　　　　　　　　　　　　
-[Next >](../best-position-for-a-service-centre "Best Position for a Service Centre")
-
-## [1514. Path with Maximum Probability (Medium)](https://leetcode.com/problems/path-with-maximum-probability "概率最大的路径")
-
-<p>You are given an undirected weighted graph of&nbsp;<code>n</code>&nbsp;nodes (0-indexed), represented by an edge list where&nbsp;<code>edges[i] = [a, b]</code>&nbsp;is an undirected edge connecting the nodes&nbsp;<code>a</code>&nbsp;and&nbsp;<code>b</code>&nbsp;with a probability of success of traversing that edge&nbsp;<code>succProb[i]</code>.</p>
-
-<p>Given two nodes&nbsp;<code>start</code>&nbsp;and&nbsp;<code>end</code>, find the path with the maximum probability of success to go from&nbsp;<code>start</code>&nbsp;to&nbsp;<code>end</code>&nbsp;and return its success probability.</p>
-
-<p>If there is no path from&nbsp;<code>start</code>&nbsp;to&nbsp;<code>end</code>, <strong>return&nbsp;0</strong>. Your answer will be accepted if it differs from the correct answer by at most <strong>1e-5</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/09/20/1558_ex1.png" style="width: 187px; height: 186px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, edges = [[0,1],[1,2],[0,2]], succProb = [0.5,0.5,0.2], start = 0, end = 2
-<strong>Output:</strong> 0.25000
-<strong>Explanation:</strong>&nbsp;There are two paths from start to end, one having a probability of success = 0.2 and the other has 0.5 * 0.5 = 0.25.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/09/20/1558_ex2.png" style="width: 189px; height: 186px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, edges = [[0,1],[1,2],[0,2]], succProb = [0.5,0.5,0.3], start = 0, end = 2
-<strong>Output:</strong> 0.30000
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/09/20/1558_ex3.png" style="width: 215px; height: 191px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, edges = [[0,1]], succProb = [0.5], start = 0, end = 2
-<strong>Output:</strong> 0.00000
-<strong>Explanation:</strong>&nbsp;There is no path between 0 and 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10^4</code></li>
-	<li><code>0 &lt;= start, end &lt; n</code></li>
-	<li><code>start != end</code></li>
-	<li><code>0 &lt;= a, b &lt; n</code></li>
-	<li><code>a != b</code></li>
-	<li><code>0 &lt;= succProb.length == edges.length &lt;= 2*10^4</code></li>
-	<li><code>0 &lt;= succProb[i] &lt;= 1</code></li>
-	<li>There is at most one edge between every two nodes.</li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-
-### Similar Questions
-  1. [Number of Ways to Arrive at Destination](../number-of-ways-to-arrive-at-destination) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Multiplying probabilities will result in precision errors.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Take log probabilities to sum up numbers instead of multiplying them.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use Dijkstra's algorithm to find the minimum path between the two nodes after negating all costs.
-</details>
diff --git a/problems/path-with-minimum-effort/README.md b/problems/path-with-minimum-effort/README.md
deleted file mode 100644
index 9cee131df..000000000
--- a/problems/path-with-minimum-effort/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../arithmetic-subarrays "Arithmetic Subarrays")
-　　　　　　　　　　　　　　　　
-[Next >](../rank-transform-of-a-matrix "Rank Transform of a Matrix")
-
-## [1631. Path With Minimum Effort (Medium)](https://leetcode.com/problems/path-with-minimum-effort "最小体力消耗路径")
-
-<p>You are a hiker preparing for an upcoming hike. You are given <code>heights</code>, a 2D array of size <code>rows x columns</code>, where <code>heights[row][col]</code> represents the height of cell <code>(row, col)</code>. You are situated in the top-left cell, <code>(0, 0)</code>, and you hope to travel to the bottom-right cell, <code>(rows-1, columns-1)</code> (i.e.,&nbsp;<strong>0-indexed</strong>). You can move <strong>up</strong>, <strong>down</strong>, <strong>left</strong>, or <strong>right</strong>, and you wish to find a route that requires the minimum <strong>effort</strong>.</p>
-
-<p>A route&#39;s <strong>effort</strong> is the <strong>maximum absolute difference</strong><strong> </strong>in heights between two consecutive cells of the route.</p>
-
-<p>Return <em>the minimum <strong>effort</strong> required to travel from the top-left cell to the bottom-right cell.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/10/04/ex1.png" style="width: 300px; height: 300px;" /></p>
-
-<pre>
-<strong>Input:</strong> heights = [[1,2,2],[3,8,2],[5,3,5]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The route of [1,3,5,3,5] has a maximum absolute difference of 2 in consecutive cells.
-This is better than the route of [1,2,2,2,5], where the maximum absolute difference is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/10/04/ex2.png" style="width: 300px; height: 300px;" /></p>
-
-<pre>
-<strong>Input:</strong> heights = [[1,2,3],[3,8,4],[5,3,5]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The route of [1,2,3,4,5] has a maximum absolute difference of 1 in consecutive cells, which is better than route [1,3,5,3,5].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/04/ex3.png" style="width: 300px; height: 300px;" />
-<pre>
-<strong>Input:</strong> heights = [[1,2,1,1,1],[1,2,1,2,1],[1,2,1,2,1],[1,2,1,2,1],[1,1,1,2,1]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> This route does not require any effort.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>rows == heights.length</code></li>
-	<li><code>columns == heights[i].length</code></li>
-	<li><code>1 &lt;= rows, columns &lt;= 100</code></li>
-	<li><code>1 &lt;= heights[i][j] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider the grid as a graph, where adjacent cells have an edge with cost of the difference between the cells.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you are given threshold k, check if it is possible to go from (0, 0) to (n-1, m-1) using only edges of ≤ k cost.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Binary search the k value.
-</details>
diff --git a/problems/paths-in-maze-that-lead-to-same-room/README.md b/problems/paths-in-maze-that-lead-to-same-room/README.md
deleted file mode 100644
index 40ea18453..000000000
--- a/problems/paths-in-maze-that-lead-to-same-room/README.md
+++ /dev/null
@@ -1,28 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../process-restricted-friend-requests "Process Restricted Friend Requests")
-　　　　　　　　　　　　　　　　
-[Next >](../two-furthest-houses-with-different-colors "Two Furthest Houses With Different Colors")
-
-## [2077. Paths in Maze That Lead to Same Room (Medium)](https://leetcode.com/problems/paths-in-maze-that-lead-to-same-room "")
-
-
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the path starts at room i, what properties must the other two rooms in the cycle have?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The other two rooms must be connected to room i, and must be connected to each other.
-</details>
diff --git a/problems/patients-with-a-condition/README.md b/problems/patients-with-a-condition/README.md
deleted file mode 100644
index 27a1f5cd3..000000000
--- a/problems/patients-with-a-condition/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-increments-on-subarrays-to-form-a-target-array "Minimum Number of Increments on Subarrays to Form a Target Array")
-　　　　　　　　　　　　　　　　
-[Next >](../shuffle-string "Shuffle String")
-
-## [1527. Patients With a Condition (Easy)](https://leetcode.com/problems/patients-with-a-condition "患某种疾病的患者")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/patients-with-a-condition/mysql_schemas.sql b/problems/patients-with-a-condition/mysql_schemas.sql
deleted file mode 100644
index 0faba4460..000000000
--- a/problems/patients-with-a-condition/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Patients (patient_id int, patient_name varchar(30), conditions varchar(100));
-Truncate table Patients;
-insert into Patients (patient_id, patient_name, conditions) values ('1', 'Daniel', 'YFEV COUGH');
-insert into Patients (patient_id, patient_name, conditions) values ('2', 'Alice', '');
-insert into Patients (patient_id, patient_name, conditions) values ('3', 'Bob', 'DIAB100 MYOP');
-insert into Patients (patient_id, patient_name, conditions) values ('4', 'George', 'ACNE DIAB100');
-insert into Patients (patient_id, patient_name, conditions) values ('5', 'Alain', 'DIAB201');
diff --git a/problems/peak-index-in-a-mountain-array/README.md b/problems/peak-index-in-a-mountain-array/README.md
deleted file mode 100644
index 05758a2dc..000000000
--- a/problems/peak-index-in-a-mountain-array/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../loud-and-rich "Loud and Rich")
-　　　　　　　　　　　　　　　　
-[Next >](../car-fleet "Car Fleet")
-
-## [852. Peak Index in a Mountain Array (Easy)](https://leetcode.com/problems/peak-index-in-a-mountain-array "山脉数组的峰顶索引")
-
-<p>Let&#39;s call an array <code>arr</code> a <strong>mountain</strong>&nbsp;if the following properties hold:</p>
-
-<ul>
-	<li><code>arr.length &gt;= 3</code></li>
-	<li>There exists some <code>i</code> with&nbsp;<code>0 &lt; i&nbsp;&lt; arr.length - 1</code>&nbsp;such that:
-	<ul>
-		<li><code>arr[0] &lt; arr[1] &lt; ... arr[i-1] &lt; arr[i] </code></li>
-		<li><code>arr[i] &gt; arr[i+1] &gt; ... &gt; arr[arr.length - 1]</code></li>
-	</ul>
-	</li>
-</ul>
-
-<p>Given an integer array <code>arr</code> that is <strong>guaranteed</strong> to be&nbsp;a mountain, return any&nbsp;<code>i</code>&nbsp;such that&nbsp;<code>arr[0] &lt; arr[1] &lt; ... arr[i - 1] &lt; arr[i] &gt; arr[i + 1] &gt; ... &gt; arr[arr.length - 1]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> arr = [0,1,0]
-<strong>Output:</strong> 1
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> arr = [0,2,1,0]
-<strong>Output:</strong> 1
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> arr = [0,10,5,2]
-<strong>Output:</strong> 1
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> arr = [3,4,5,1]
-<strong>Output:</strong> 2
-</pre><p><strong>Example 5:</strong></p>
-<pre><strong>Input:</strong> arr = [24,69,100,99,79,78,67,36,26,19]
-<strong>Output:</strong> 2
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>arr</code> is <strong>guaranteed</strong> to be a mountain array.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Finding the <code>O(n)</code> is straightforward, could you find an <code>O(log(n))</code> solution?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Find Peak Element](../find-peak-element) (Medium)
diff --git a/problems/peak-index-in-a-mountain-array/peak_index_in_a_mountain_array.go b/problems/peak-index-in-a-mountain-array/peak_index_in_a_mountain_array.go
deleted file mode 100644
index 02a8b917a..000000000
--- a/problems/peak-index-in-a-mountain-array/peak_index_in_a_mountain_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem852
diff --git a/problems/peak-index-in-a-mountain-array/peak_index_in_a_mountain_array_test.go b/problems/peak-index-in-a-mountain-array/peak_index_in_a_mountain_array_test.go
deleted file mode 100644
index 02a8b917a..000000000
--- a/problems/peak-index-in-a-mountain-array/peak_index_in_a_mountain_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem852
diff --git a/problems/peeking-iterator/README.md b/problems/peeking-iterator/README.md
deleted file mode 100644
index c922a69d3..000000000
--- a/problems/peeking-iterator/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../move-zeroes "Move Zeroes")
-　　　　　　　　　　　　　　　　
-[Next >](../inorder-successor-in-bst "Inorder Successor in BST")
-
-## [284. Peeking Iterator (Medium)](https://leetcode.com/problems/peeking-iterator "窥探迭代器")
-
-<p>Design an iterator that supports the <code>peek</code> operation on an existing iterator in addition to the <code>hasNext</code> and the <code>next</code> operations.</p>
-
-<p>Implement the <code>PeekingIterator</code> class:</p>
-
-<ul>
-	<li><code>PeekingIterator(Iterator&lt;int&gt; nums)</code> Initializes the object with the given integer iterator <code>iterator</code>.</li>
-	<li><code>int next()</code> Returns the next element in the array and moves the pointer to the next element.</li>
-	<li><code>boolean hasNext()</code> Returns <code>true</code> if there are still elements in the array.</li>
-	<li><code>int peek()</code> Returns the next element in the array <strong>without</strong> moving the pointer.</li>
-</ul>
-
-<p><strong>Note:</strong> Each language may have a different implementation of the constructor and <code>Iterator</code>, but they all support the <code>int next()</code> and <code>boolean hasNext()</code> functions.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;PeekingIterator&quot;, &quot;next&quot;, &quot;peek&quot;, &quot;next&quot;, &quot;next&quot;, &quot;hasNext&quot;]
-[[[1, 2, 3]], [], [], [], [], []]
-<strong>Output</strong>
-[null, 1, 2, 2, 3, false]
-
-<strong>Explanation</strong>
-PeekingIterator peekingIterator = new PeekingIterator([1, 2, 3]); // [<u><strong>1</strong></u>,2,3]
-peekingIterator.next();    // return 1, the pointer moves to the next element [1,<u><strong>2</strong></u>,3].
-peekingIterator.peek();    // return 2, the pointer does not move [1,<u><strong>2</strong></u>,3].
-peekingIterator.next();    // return 2, the pointer moves to the next element [1,2,<u><strong>3</strong></u>]
-peekingIterator.next();    // return 3, the pointer moves to the next element [1,2,3]
-peekingIterator.hasNext(); // return False
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 1000</code></li>
-	<li>All the calls to <code>next</code> and <code>peek</code> are valid.</li>
-	<li>At most <code>1000</code> calls will be made to <code>next</code>, <code>hasNext</code>, and <code>peek</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> How would you extend your design to be generic and work with all types, not just integer?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Iterator](../../tag/iterator/README.md)]
-
-### Similar Questions
-  1. [Binary Search Tree Iterator](../binary-search-tree-iterator) (Medium)
-  1. [Flatten 2D Vector](../flatten-2d-vector) (Medium)
-  1. [Zigzag Iterator](../zigzag-iterator) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think of "looking ahead". You want to cache the next element.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is one variable sufficient? Why or why not?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Test your design with call order of <code>peek()</code> before <code>next()</code> vs <code>next()</code> before <code>peek()</code>.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For a clean implementation, check out <a href="https://github.com/google/guava/blob/703ef758b8621cfbab16814f01ddcc5324bdea33/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/Iterators.java#L1125" target="_blank">Google's guava library source code</a>.
-</details>
diff --git a/problems/peeking-iterator/peeking_iterator.go b/problems/peeking-iterator/peeking_iterator.go
deleted file mode 100644
index 801bd886d..000000000
--- a/problems/peeking-iterator/peeking_iterator.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem284
diff --git a/problems/peeking-iterator/peeking_iterator.py b/problems/peeking-iterator/peeking_iterator.py
deleted file mode 100755
index 1cbe1b002..000000000
--- a/problems/peeking-iterator/peeking_iterator.py
+++ /dev/null
@@ -1,55 +0,0 @@
-#!/usr/bin/env python
-
-# Below is the interface for Iterator, which is already defined for you.
-#
-# class Iterator:
-#     def __init__(self, nums):
-#         """
-#         Initializes an iterator object to the beginning of a list.
-#         :type nums: List[int]
-#         """
-#
-#     def hasNext(self):
-#         """
-#         Returns true if the iteration has more elements.
-#         :rtype: bool
-#         """
-#
-#     def next(self):
-#         """
-#         Returns the next element in the iteration.
-#         :rtype: int
-#         """
-
-class PeekingIterator:
-    def __init__(self, iterator):
-        """
-        Initialize your data structure here.
-        :type iterator: Iterator
-        """
-        
-
-    def peek(self):
-        """
-        Returns the next element in the iteration without advancing the iterator.
-        :rtype: int
-        """
-        
-
-    def next(self):
-        """
-        :rtype: int
-        """
-        
-
-    def hasNext(self):
-        """
-        :rtype: bool
-        """
-        
-
-# Your PeekingIterator object will be instantiated and called as such:
-# iter = PeekingIterator(Iterator(nums))
-# while iter.hasNext():
-#     val = iter.peek()   # Get the next element but not advance the iterator.
-#     iter.next()         # Should return the same value as [val].
\ No newline at end of file
diff --git a/problems/peeking-iterator/peeking_iterator_test.go b/problems/peeking-iterator/peeking_iterator_test.go
deleted file mode 100644
index 801bd886d..000000000
--- a/problems/peeking-iterator/peeking_iterator_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem284
diff --git a/problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list/README.md b/problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list/README.md
deleted file mode 100644
index 7c32ea78e..000000000
--- a/problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rearrange-words-in-a-sentence "Rearrange Words in a Sentence")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-darts-inside-of-a-circular-dartboard "Maximum Number of Darts Inside of a Circular Dartboard")
-
-## [1452. People Whose List of Favorite Companies Is Not a Subset of Another List (Medium)](https://leetcode.com/problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list "收藏清单")
-
-<p>Given the array <code>favoriteCompanies</code> where <code>favoriteCompanies[i]</code> is the list of favorites companies for the <code>ith</code> person (<strong>indexed from 0</strong>).</p>
-
-<p><em>Return the indices of people whose list of favorite companies is not a <strong>subset</strong> of any other list of favorites companies</em>. You must return the indices in increasing order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> favoriteCompanies = [[&quot;leetcode&quot;,&quot;google&quot;,&quot;facebook&quot;],[&quot;google&quot;,&quot;microsoft&quot;],[&quot;google&quot;,&quot;facebook&quot;],[&quot;google&quot;],[&quot;amazon&quot;]]
-<strong>Output:</strong> [0,1,4] 
-<strong>Explanation:</strong> 
-Person with index=2 has favoriteCompanies[2]=[&quot;google&quot;,&quot;facebook&quot;] which is a subset of favoriteCompanies[0]=[&quot;leetcode&quot;,&quot;google&quot;,&quot;facebook&quot;] corresponding to the person with index 0. 
-Person with index=3 has favoriteCompanies[3]=[&quot;google&quot;] which is a subset of favoriteCompanies[0]=[&quot;leetcode&quot;,&quot;google&quot;,&quot;facebook&quot;] and favoriteCompanies[1]=[&quot;google&quot;,&quot;microsoft&quot;]. 
-Other lists of favorite companies are not a subset of another list, therefore, the answer is [0,1,4].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> favoriteCompanies = [[&quot;leetcode&quot;,&quot;google&quot;,&quot;facebook&quot;],[&quot;leetcode&quot;,&quot;amazon&quot;],[&quot;facebook&quot;,&quot;google&quot;]]
-<strong>Output:</strong> [0,1] 
-<strong>Explanation:</strong> In this case favoriteCompanies[2]=[&quot;facebook&quot;,&quot;google&quot;] is a subset of favoriteCompanies[0]=[&quot;leetcode&quot;,&quot;google&quot;,&quot;facebook&quot;], therefore, the answer is [0,1].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> favoriteCompanies = [[&quot;leetcode&quot;],[&quot;google&quot;],[&quot;facebook&quot;],[&quot;amazon&quot;]]
-<strong>Output:</strong> [0,1,2,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= favoriteCompanies.length &lt;= 100</code></li>
-	<li><code>1 &lt;= favoriteCompanies[i].length &lt;= 500</code></li>
-	<li><code>1 &lt;= favoriteCompanies[i][j].length &lt;= 20</code></li>
-	<li>All strings in <code>favoriteCompanies[i]</code> are <strong>distinct</strong>.</li>
-	<li>All lists of favorite companies are <strong>distinct</strong>, that is, If we sort alphabetically each list then <code>favoriteCompanies[i] != favoriteCompanies[j].</code></li>
-	<li>All strings consist of lowercase English letters only.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use hashing to convert company names in numbers and then for each list check if this is a subset of any other list.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In order to check if a list is a subset of another list, use two pointers technique to get a linear solution for this task. The total complexity will be O(n^2 * m) where n is the number of lists and m is the maximum number of elements in a list.
-</details>
diff --git a/problems/percentage-of-users-attended-a-contest/README.md b/problems/percentage-of-users-attended-a-contest/README.md
deleted file mode 100644
index 7773dffab..000000000
--- a/problems/percentage-of-users-attended-a-contest/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rank-transform-of-a-matrix "Rank Transform of a Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../add-two-polynomials-represented-as-linked-lists "Add Two Polynomials Represented as Linked Lists")
-
-## [1633. Percentage of Users Attended a Contest (Easy)](https://leetcode.com/problems/percentage-of-users-attended-a-contest "各赛事的用户注册率")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/percentage-of-users-attended-a-contest/mysql_schemas.sql b/problems/percentage-of-users-attended-a-contest/mysql_schemas.sql
deleted file mode 100644
index 722f57248..000000000
--- a/problems/percentage-of-users-attended-a-contest/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create table If Not Exists Users (user_id int, user_name varchar(20));
-Create table If Not Exists Register (contest_id int, user_id int);
-Truncate table Users;
-insert into Users (user_id, user_name) values ('6', 'Alice');
-insert into Users (user_id, user_name) values ('2', 'Bob');
-insert into Users (user_id, user_name) values ('7', 'Alex');
-Truncate table Register;
-insert into Register (contest_id, user_id) values ('215', '6');
-insert into Register (contest_id, user_id) values ('209', '2');
-insert into Register (contest_id, user_id) values ('208', '2');
-insert into Register (contest_id, user_id) values ('210', '6');
-insert into Register (contest_id, user_id) values ('208', '6');
-insert into Register (contest_id, user_id) values ('209', '7');
-insert into Register (contest_id, user_id) values ('209', '6');
-insert into Register (contest_id, user_id) values ('215', '7');
-insert into Register (contest_id, user_id) values ('208', '7');
-insert into Register (contest_id, user_id) values ('210', '2');
-insert into Register (contest_id, user_id) values ('207', '2');
-insert into Register (contest_id, user_id) values ('210', '7');
diff --git a/problems/perfect-number/README.md b/problems/perfect-number/README.md
deleted file mode 100644
index 49cdc968c..000000000
--- a/problems/perfect-number/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../relative-ranks "Relative Ranks")
-　　　　　　　　　　　　　　　　
-[Next >](../most-frequent-subtree-sum "Most Frequent Subtree Sum")
-
-## [507. Perfect Number (Easy)](https://leetcode.com/problems/perfect-number "完美数")
-
-<p>A <a href="https://en.wikipedia.org/wiki/Perfect_number" target="_blank"><strong>perfect number</strong></a> is a <strong>positive integer</strong> that is equal to the sum of its <strong>positive divisors</strong>, excluding the number itself. A <strong>divisor</strong> of an integer <code>x</code> is an integer that can divide <code>x</code> evenly.</p>
-
-<p>Given an integer <code>n</code>, return <code>true</code><em> if </em><code>n</code><em> is a perfect number, otherwise return </em><code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 28
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 28 = 1 + 2 + 4 + 7 + 14
-1, 2, 4, 7, and 14 are all divisors of 28.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 6
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 496
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 8128
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 2
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Self Dividing Numbers](../self-dividing-numbers) (Easy)
diff --git a/problems/perfect-number/perfect_number.go b/problems/perfect-number/perfect_number.go
deleted file mode 100644
index 7a53b0d82..000000000
--- a/problems/perfect-number/perfect_number.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem507
-
-// Solution 1
-func checkPerfectNumber(num int) bool {
-	if num < 6 {
-		return false
-	}
-	sum, mid := 1, num
-	for i := 2; i < mid; i++ {
-		if num%i == 0 {
-			n := num / i
-			sum += i + n
-			if mid > n {
-				mid = n
-			}
-		}
-	}
-	return sum == num
-}
-
-// Solution 2
-func checkPerfectNumber2(num int) bool {
-	m := map[int]bool{
-		6:        true,
-		28:       true,
-		496:      true,
-		8128:     true,
-		33550336: true,
-	}
-	return m[num]
-}
diff --git a/problems/perfect-number/perfect_number_test.go b/problems/perfect-number/perfect_number_test.go
deleted file mode 100644
index fff1471b0..000000000
--- a/problems/perfect-number/perfect_number_test.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package problem507
-
-import "testing"
-
-type testType struct {
-	in   int
-	want bool
-}
-
-func TestCheckPerfectNumber(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   28,
-			want: true,
-		},
-		{
-			in:   6,
-			want: true,
-		},
-		{
-			in:   24,
-			want: false,
-		},
-		{
-			in:   1,
-			want: false,
-		},
-		{
-			in:   33550336,
-			want: true,
-		},
-	}
-	// Solution 1
-	for _, tt := range tests {
-		got := checkPerfectNumber(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-	// Solution 2
-	for _, tt := range tests {
-		got := checkPerfectNumber2(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/perfect-rectangle/README.md b/problems/perfect-rectangle/README.md
deleted file mode 100644
index 971198a6f..000000000
--- a/problems/perfect-rectangle/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../elimination-game "Elimination Game")
-　　　　　　　　　　　　　　　　
-[Next >](../is-subsequence "Is Subsequence")
-
-## [391. Perfect Rectangle (Hard)](https://leetcode.com/problems/perfect-rectangle "完美矩形")
-
-<p>Given an array <code>rectangles</code> where <code>rectangles[i] = [x<sub>i</sub>, y<sub>i</sub>, a<sub>i</sub>, b<sub>i</sub>]</code> represents an axis-aligned rectangle. The bottom-left point of the rectangle is <code>(x<sub>i</sub>, y<sub>i</sub>)</code> and the top-right point of it is <code>(a<sub>i</sub>, b<sub>i</sub>)</code>.</p>
-
-<p>Return <code>true</code> <em>if all the rectangles together form an exact cover of a rectangular region</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/27/perectrec1-plane.jpg" style="width: 300px; height: 294px;" />
-<pre>
-<strong>Input:</strong> rectangles = [[1,1,3,3],[3,1,4,2],[3,2,4,4],[1,3,2,4],[2,3,3,4]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> All 5 rectangles together form an exact cover of a rectangular region.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/27/perfectrec2-plane.jpg" style="width: 300px; height: 294px;" />
-<pre>
-<strong>Input:</strong> rectangles = [[1,1,2,3],[1,3,2,4],[3,1,4,2],[3,2,4,4]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Because there is a gap between the two rectangular regions.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/27/perfecrrec4-plane.jpg" style="width: 300px; height: 294px;" />
-<pre>
-<strong>Input:</strong> rectangles = [[1,1,3,3],[3,1,4,2],[1,3,2,4],[2,2,4,4]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Because two of the rectangles overlap with each other.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rectangles.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>rectangles[i].length == 4</code></li>
-	<li><code>-10<sup>5</sup> &lt;= x<sub>i</sub>, y<sub>i</sub>, a<sub>i</sub>, b<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Line Sweep](../../tag/line-sweep/README.md)]
diff --git a/problems/perfect-rectangle/perfect_rectangle.go b/problems/perfect-rectangle/perfect_rectangle.go
deleted file mode 100644
index 290c0233e..000000000
--- a/problems/perfect-rectangle/perfect_rectangle.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem391
diff --git a/problems/perfect-rectangle/perfect_rectangle_test.go b/problems/perfect-rectangle/perfect_rectangle_test.go
deleted file mode 100644
index 290c0233e..000000000
--- a/problems/perfect-rectangle/perfect_rectangle_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem391
diff --git a/problems/perfect-squares/README.md b/problems/perfect-squares/README.md
deleted file mode 100644
index 75653ae8d..000000000
--- a/problems/perfect-squares/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../first-bad-version "First Bad Version")
-　　　　　　　　　　　　　　　　
-[Next >](../wiggle-sort "Wiggle Sort")
-
-## [279. Perfect Squares (Medium)](https://leetcode.com/problems/perfect-squares "完全平方数")
-
-<p>Given an integer <code>n</code>, return <em>the least number of perfect square numbers that sum to</em> <code>n</code>.</p>
-
-<p>A <strong>perfect square</strong> is an integer that is the square of an integer; in other words, it is the product of some integer with itself. For example, <code>1</code>, <code>4</code>, <code>9</code>, and <code>16</code> are perfect squares while <code>3</code> and <code>11</code> are not.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 12
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 12 = 4 + 4 + 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 13
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 13 = 4 + 9.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Count Primes](../count-primes) (Medium)
-  1. [Ugly Number II](../ugly-number-ii) (Medium)
diff --git a/problems/perfect-squares/perfect_squares.go b/problems/perfect-squares/perfect_squares.go
deleted file mode 100644
index 4f4c1a3ef..000000000
--- a/problems/perfect-squares/perfect_squares.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem279
diff --git a/problems/perfect-squares/perfect_squares_test.go b/problems/perfect-squares/perfect_squares_test.go
deleted file mode 100644
index 4f4c1a3ef..000000000
--- a/problems/perfect-squares/perfect_squares_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem279
diff --git a/problems/perform-string-shifts/README.md b/problems/perform-string-shifts/README.md
deleted file mode 100644
index b9c87caf9..000000000
--- a/problems/perform-string-shifts/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../counting-elements "Counting Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../leftmost-column-with-at-least-a-one "Leftmost Column with at Least a One")
-
-## [1427. Perform String Shifts (Easy)](https://leetcode.com/problems/perform-string-shifts "字符串的左右移")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Intuitively performing all shift operations is acceptable due to the constraints.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You may notice that left shift cancels the right shift, so count the total left shift times (may be negative if the final result is right shift), and perform it once.
-</details>
diff --git a/problems/permutation-in-string/README.md b/problems/permutation-in-string/README.md
deleted file mode 100644
index 04f2c828a..000000000
--- a/problems/permutation-in-string/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reshape-the-matrix "Reshape the Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-vacation-days "Maximum Vacation Days")
-
-## [567. Permutation in String (Medium)](https://leetcode.com/problems/permutation-in-string "字符串的排列")
-
-<p>Given two strings <code>s1</code> and <code>s2</code>, return <code>true</code><em> if </em><code>s2</code><em> contains a permutation of </em><code>s1</code><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>In other words, return <code>true</code> if one of <code>s1</code>&#39;s permutations is the substring of <code>s2</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;ab&quot;, s2 = &quot;eidbaooo&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> s2 contains one permutation of s1 (&quot;ba&quot;).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;ab&quot;, s2 = &quot;eidboaoo&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s1.length, s2.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s1</code> and <code>s2</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Minimum Window Substring](../minimum-window-substring) (Hard)
-  1. [Find All Anagrams in a String](../find-all-anagrams-in-a-string) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Obviously, brute force will result in TLE. Think of something else.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How will you check whether one string is a permutation of another string?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-One way is to sort the string and then compare. But, Is there a better way?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-If one string is a permutation of another string then they must one common metric. What is that?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Both strings must have same character frequencies, if  one is permutation of another. Which data structure should be used to store frequencies?
-</details>
-
-<details>
-<summary>Hint 6</summary>
-What about hash table?  An array of size 26?
-</details>
diff --git a/problems/permutation-in-string/permutation_in_string.go b/problems/permutation-in-string/permutation_in_string.go
deleted file mode 100644
index f59655f61..000000000
--- a/problems/permutation-in-string/permutation_in_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem567
diff --git a/problems/permutation-in-string/permutation_in_string_test.go b/problems/permutation-in-string/permutation_in_string_test.go
deleted file mode 100644
index f59655f61..000000000
--- a/problems/permutation-in-string/permutation_in_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem567
diff --git a/problems/permutation-sequence/README.md b/problems/permutation-sequence/README.md
deleted file mode 100644
index 6fd641631..000000000
--- a/problems/permutation-sequence/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../spiral-matrix-ii "Spiral Matrix II")
-　　　　　　　　　　　　　　　　
-[Next >](../rotate-list "Rotate List")
-
-## [60. Permutation Sequence (Hard)](https://leetcode.com/problems/permutation-sequence "排列序列")
-
-<p>The set <code>[1, 2, 3, ...,&nbsp;n]</code> contains a total of <code>n!</code> unique permutations.</p>
-
-<p>By listing and labeling all of the permutations in order, we get the following sequence for <code>n = 3</code>:</p>
-
-<ol>
-	<li><code>&quot;123&quot;</code></li>
-	<li><code>&quot;132&quot;</code></li>
-	<li><code>&quot;213&quot;</code></li>
-	<li><code>&quot;231&quot;</code></li>
-	<li><code>&quot;312&quot;</code></li>
-	<li><code>&quot;321&quot;</code></li>
-</ol>
-
-<p>Given <code>n</code> and <code>k</code>, return the <code>k<sup>th</sup></code> permutation sequence.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 3, k = 3
-<strong>Output:</strong> "213"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 4, k = 9
-<strong>Output:</strong> "2314"
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> n = 3, k = 1
-<strong>Output:</strong> "123"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 9</code></li>
-	<li><code>1 &lt;= k &lt;= n!</code></li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Next Permutation](../next-permutation) (Medium)
-  1. [Permutations](../permutations) (Medium)
diff --git a/problems/permutation-sequence/permutation_sequence.go b/problems/permutation-sequence/permutation_sequence.go
deleted file mode 100644
index ed1f1bc6b..000000000
--- a/problems/permutation-sequence/permutation_sequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem60
diff --git a/problems/permutation-sequence/permutation_sequence_test.go b/problems/permutation-sequence/permutation_sequence_test.go
deleted file mode 100644
index ed1f1bc6b..000000000
--- a/problems/permutation-sequence/permutation_sequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem60
diff --git a/problems/permutations-ii/README.md b/problems/permutations-ii/README.md
deleted file mode 100644
index ec4163911..000000000
--- a/problems/permutations-ii/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../permutations "Permutations")
-　　　　　　　　　　　　　　　　
-[Next >](../rotate-image "Rotate Image")
-
-## [47. Permutations II (Medium)](https://leetcode.com/problems/permutations-ii "全排列 II")
-
-<p>Given a collection of numbers, <code>nums</code>,&nbsp;that might contain duplicates, return <em>all possible unique permutations <strong>in any order</strong>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,2]
-<strong>Output:</strong>
-[[1,1,2],
- [1,2,1],
- [2,1,1]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 8</code></li>
-	<li><code>-10 &lt;= nums[i] &lt;= 10</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Next Permutation](../next-permutation) (Medium)
-  1. [Permutations](../permutations) (Medium)
-  1. [Palindrome Permutation II](../palindrome-permutation-ii) (Medium)
-  1. [Number of Squareful Arrays](../number-of-squareful-arrays) (Hard)
diff --git a/problems/permutations-ii/permutations_ii.go b/problems/permutations-ii/permutations_ii.go
deleted file mode 100644
index 277821276..000000000
--- a/problems/permutations-ii/permutations_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem47
diff --git a/problems/permutations-ii/permutations_ii_test.go b/problems/permutations-ii/permutations_ii_test.go
deleted file mode 100644
index 277821276..000000000
--- a/problems/permutations-ii/permutations_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem47
diff --git a/problems/permutations/README.md b/problems/permutations/README.md
deleted file mode 100644
index 6e8ecca6b..000000000
--- a/problems/permutations/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../jump-game-ii "Jump Game II")
-　　　　　　　　　　　　　　　　
-[Next >](../permutations-ii "Permutations II")
-
-## [46. Permutations (Medium)](https://leetcode.com/problems/permutations "全排列")
-
-<p>Given an array <code>nums</code> of distinct integers, return <em>all the possible permutations</em>. You can return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [0,1]
-<strong>Output:</strong> [[0,1],[1,0]]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [1]
-<strong>Output:</strong> [[1]]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 6</code></li>
-	<li><code>-10 &lt;= nums[i] &lt;= 10</code></li>
-	<li>All the integers of <code>nums</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Next Permutation](../next-permutation) (Medium)
-  1. [Permutations II](../permutations-ii) (Medium)
-  1. [Permutation Sequence](../permutation-sequence) (Hard)
-  1. [Combinations](../combinations) (Medium)
diff --git a/problems/permutations/permutations.go b/problems/permutations/permutations.go
deleted file mode 100644
index b142db5fd..000000000
--- a/problems/permutations/permutations.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem46
diff --git a/problems/permutations/permutations_test.go b/problems/permutations/permutations_test.go
deleted file mode 100644
index b142db5fd..000000000
--- a/problems/permutations/permutations_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem46
diff --git a/problems/pizza-with-3n-slices/README.md b/problems/pizza-with-3n-slices/README.md
deleted file mode 100644
index eb813cd89..000000000
--- a/problems/pizza-with-3n-slices/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-integers-by-the-power-value "Sort Integers by The Power Value")
-　　　　　　　　　　　　　　　　
-[Next >](../create-target-array-in-the-given-order "Create Target Array in the Given Order")
-
-## [1388. Pizza With 3n Slices (Hard)](https://leetcode.com/problems/pizza-with-3n-slices "3n 块披萨")
-
-<p>There is a pizza with <code>3n</code> slices of varying size, you and your friends will take slices of pizza as follows:</p>
-
-<ul>
-	<li>You will pick <strong>any</strong> pizza slice.</li>
-	<li>Your friend Alice will pick the next slice in the anti-clockwise direction of your pick.</li>
-	<li>Your friend Bob will pick the next slice in the clockwise direction of your pick.</li>
-	<li>Repeat until there are no more slices of pizzas.</li>
-</ul>
-
-<p>Given an integer array <code>slices</code> that represent the sizes of the pizza slices in a clockwise direction, return <em>the maximum possible sum of slice sizes that you can pick</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/18/sample_3_1723.png" style="width: 500px; height: 266px;" />
-<pre>
-<strong>Input:</strong> slices = [1,2,3,4,5,6]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> Pick pizza slice of size 4, Alice and Bob will pick slices with size 3 and 5 respectively. Then Pick slices with size 6, finally Alice and Bob will pick slice of size 2 and 1 respectively. Total = 4 + 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/18/sample_4_1723.png" style="width: 500px; height: 299px;" />
-<pre>
-<strong>Input:</strong> slices = [8,9,8,6,1,1]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> Pick pizza slice of size 8 in each turn. If you pick slice with size 9 your partners will pick slices of size 8.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 * n == slices.length</code></li>
-	<li><code>1 &lt;= slices.length &lt;= 500</code></li>
-	<li><code>1 &lt;= slices[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-By studying the pattern of the operations, we can find out that the problem is equivalent to: Given an integer array with size 3N, select N integers with maximum sum and any selected integers are not next to each other in the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The first one in the array is considered next to the last one in the array. Use Dynamic Programming to solve it.
-</details>
diff --git a/problems/plates-between-candles/README.md b/problems/plates-between-candles/README.md
deleted file mode 100644
index ae2f893fb..000000000
--- a/problems/plates-between-candles/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-best-non-overlapping-events "Two Best Non-Overlapping Events")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-valid-move-combinations-on-chessboard "Number of Valid Move Combinations On Chessboard")
-
-## [2055. Plates Between Candles (Medium)](https://leetcode.com/problems/plates-between-candles "蜡烛之间的盘子")
-
-<p>There is a long table with a line of plates and candles arranged on top of it. You are given a <strong>0-indexed</strong> string <code>s</code> consisting of characters <code>&#39;*&#39;</code> and <code>&#39;|&#39;</code> only, where a <code>&#39;*&#39;</code> represents a <strong>plate</strong> and a <code>&#39;|&#39;</code> represents a <strong>candle</strong>.</p>
-
-<p>You are also given a <strong>0-indexed</strong> 2D integer array <code>queries</code> where <code>queries[i] = [left<sub>i</sub>, right<sub>i</sub>]</code> denotes the <strong>substring</strong> <code>s[left<sub>i</sub>...right<sub>i</sub>]</code> (<strong>inclusive</strong>). For each query, you need to find the <strong>number</strong> of plates <strong>between candles</strong> that are <strong>in the substring</strong>. A plate is considered <strong>between candles</strong> if there is at least one candle to its left <strong>and</strong> at least one candle to its right <strong>in the substring</strong>.</p>
-
-<ul>
-	<li>For example, <code>s = &quot;||**||**|*&quot;</code>, and a query <code>[3, 8]</code> denotes the substring <code>&quot;*||<strong><u>**</u></strong>|&quot;</code>. The number of plates between candles in this substring is <code>2</code>, as each of the two plates has at least one candle <strong>in the substring</strong> to its left <strong>and</strong> right.</li>
-</ul>
-
-<p>Return <em>an integer array</em> <code>answer</code> <em>where</em> <code>answer[i]</code> <em>is the answer to the</em> <code>i<sup>th</sup></code> <em>query</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="ex-1" src="https://assets.leetcode.com/uploads/2021/10/04/ex-1.png" style="width: 400px; height: 134px;" />
-<pre>
-<strong>Input:</strong> s = &quot;**|**|***|&quot;, queries = [[2,5],[5,9]]
-<strong>Output:</strong> [2,3]
-<strong>Explanation:</strong>
-- queries[0] has two plates between candles.
-- queries[1] has three plates between candles.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="ex-2" src="https://assets.leetcode.com/uploads/2021/10/04/ex-2.png" style="width: 600px; height: 193px;" />
-<pre>
-<strong>Input:</strong> s = &quot;***|**|*****|**||**|*&quot;, queries = [[1,17],[4,5],[14,17],[5,11],[15,16]]
-<strong>Output:</strong> [9,0,0,0,0]
-<strong>Explanation:</strong>
-- queries[0] has nine plates between candles.
-- The other queries have zero plates between candles.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of <code>&#39;*&#39;</code> and <code>&#39;|&#39;</code> characters.</li>
-	<li><code>1 &lt;= queries.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>queries[i].length == 2</code></li>
-	<li><code>0 &lt;= left<sub>i</sub> &lt;= right<sub>i</sub> &lt; s.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you find the indices of the most left and right candles for a given substring, perhaps by using binary search (or better) over an array of indices of all the bars?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Once the indices of the most left and right bars are determined, how can you efficiently count the number of plates within the range? Prefix sums?
-</details>
diff --git a/problems/play-with-chips/README.md b/problems/play-with-chips/README.md
deleted file mode 100644
index 7c45594d3..000000000
--- a/problems/play-with-chips/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-palindrome-iii "Valid Palindrome III")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-arithmetic-subsequence-of-given-difference "Longest Arithmetic Subsequence of Given Difference")
-
-## [1217. Play with Chips (Easy)](https://leetcode.com/problems/play-with-chips "玩筹码")
-
-<p>There are some chips, and the i-th chip is at position <code>chips[i]</code>.</p>
-
-<p>You can perform any of the two following types of moves <strong>any number of times</strong> (possibly&nbsp;zero) <strong>on any chip</strong>:</p>
-
-<ul>
-	<li>Move the <code>i</code>-th chip&nbsp;by&nbsp;2 units to the left or to the right with a cost of <strong>0</strong>.</li>
-	<li>Move&nbsp;the <code>i</code>-th chip&nbsp;by&nbsp;1 unit to the left or to the right with a cost of&nbsp;<strong>1</strong>.</li>
-</ul>
-
-<p>There can be two or more chips&nbsp;at the same position initially.</p>
-
-<p>Return the&nbsp;minimum cost needed to move all the chips to the same position (any position).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> chips = [1,2,3]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Second chip will be moved to positon 3 with cost 1. First chip will be moved to position 3 with cost 0. Total cost is 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> chips = [2,2,2,3,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Both fourth and fifth chip will be moved to position two with cost 1. Total minimum cost will be 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= chips.length &lt;= 100</code></li>
-	<li><code>1 &lt;= chips[i] &lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The first move keeps the parity of the element as it is.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The second move changes the parity of the element.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Since the first move is free, if all the numbers have the same parity, the answer would be zero.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Find the minimum cost to make all the numbers have the same parity.
-</details>
diff --git a/problems/plus-one-linked-list/README.md b/problems/plus-one-linked-list/README.md
deleted file mode 100644
index ae6a641b4..000000000
--- a/problems/plus-one-linked-list/README.md
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-divisible-subset "Largest Divisible Subset")
-　　　　　　　　　　　　　　　　
-[Next >](../range-addition "Range Addition")
-
-## [369. Plus One Linked List (Medium)](https://leetcode.com/problems/plus-one-linked-list "给单链表加一")
-
-<p>Given a non-negative integer represented as <b>non-empty</b> a singly linked list of digits, plus one to the integer.</p>
-
-<p>You may assume the integer do not contain any leading zero, except the number 0 itself.</p>
-
-<p>The digits are stored such that the most significant digit is at the head of the list.</p>
-
-<div>
-<p><strong>Example :</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[1,2,3]</span>
-<strong>Output: </strong><span id="example-output-1">[1,2,4]</span>
-</pre>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Plus One](../plus-one) (Easy)
diff --git a/problems/plus-one-linked-list/plus_one_linked_list.go b/problems/plus-one-linked-list/plus_one_linked_list.go
deleted file mode 100644
index 97566c22b..000000000
--- a/problems/plus-one-linked-list/plus_one_linked_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem369
diff --git a/problems/plus-one-linked-list/plus_one_linked_list_test.go b/problems/plus-one-linked-list/plus_one_linked_list_test.go
deleted file mode 100644
index 97566c22b..000000000
--- a/problems/plus-one-linked-list/plus_one_linked_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem369
diff --git a/problems/plus-one/README.md b/problems/plus-one/README.md
deleted file mode 100644
index 8e2a7d0b8..000000000
--- a/problems/plus-one/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-number "Valid Number")
-　　　　　　　　　　　　　　　　
-[Next >](../add-binary "Add Binary")
-
-## [66. Plus One (Easy)](https://leetcode.com/problems/plus-one "加一")
-
-<p>You are given a <strong>large integer</strong> represented as an integer array <code>digits</code>, where each <code>digits[i]</code> is the <code>i<sup>th</sup></code> digit of the integer. The digits are ordered from most significant to least significant in left-to-right order. The large integer does not contain any leading <code>0</code>&#39;s.</p>
-
-<p>Increment the large integer by one and return <em>the resulting array of digits</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [1,2,3]
-<strong>Output:</strong> [1,2,4]
-<strong>Explanation:</strong> The array represents the integer 123.
-Incrementing by one gives 123 + 1 = 124.
-Thus, the result should be [1,2,4].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [4,3,2,1]
-<strong>Output:</strong> [4,3,2,2]
-<strong>Explanation:</strong> The array represents the integer 4321.
-Incrementing by one gives 4321 + 1 = 4322.
-Thus, the result should be [4,3,2,2].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [0]
-<strong>Output:</strong> [1]
-<strong>Explanation:</strong> The array represents the integer 0.
-Incrementing by one gives 0 + 1 = 1.
-Thus, the result should be [1].
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> digits = [9]
-<strong>Output:</strong> [1,0]
-<strong>Explanation:</strong> The array represents the integer 9.
-Incrementing by one gives 9 + 1 = 10.
-Thus, the result should be [1,0].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= digits.length &lt;= 100</code></li>
-	<li><code>0 &lt;= digits[i] &lt;= 9</code></li>
-	<li><code>digits</code> does not contain any leading <code>0</code>&#39;s.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Multiply Strings](../multiply-strings) (Medium)
-  1. [Add Binary](../add-binary) (Easy)
-  1. [Plus One Linked List](../plus-one-linked-list) (Medium)
-  1. [Add to Array-Form of Integer](../add-to-array-form-of-integer) (Easy)
diff --git a/problems/plus-one/plus_one.go b/problems/plus-one/plus_one.go
deleted file mode 100644
index 011443bc7..000000000
--- a/problems/plus-one/plus_one.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem66
-
-func plusOne(digits []int) []int {
-	l := len(digits)
-	for i := l - 1; i >= 0; i-- {
-		if digits[i] < 9 {
-			digits[i]++
-			return digits
-		}
-		digits[i] = 0
-	}
-	if digits[0] == 0 {
-		digits = append([]int{1}, digits...)
-	}
-	return digits
-}
diff --git a/problems/plus-one/plus_one_test.go b/problems/plus-one/plus_one_test.go
deleted file mode 100644
index 9f1786863..000000000
--- a/problems/plus-one/plus_one_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem66
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestPlusOne(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3},
-			want: []int{1, 2, 4},
-		},
-		{
-			in:   []int{4, 3, 2, 1},
-			want: []int{4, 3, 2, 2},
-		},
-		{
-			in:   []int{1, 2, 9, 9},
-			want: []int{1, 3, 0, 0},
-		},
-		{
-			in:   []int{9, 9},
-			want: []int{1, 0, 0},
-		},
-	}
-
-	for _, tt := range tests {
-		got := plusOne(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/poor-pigs/README.md b/problems/poor-pigs/README.md
deleted file mode 100644
index ed7c5ff79..000000000
--- a/problems/poor-pigs/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../circular-array-loop "Circular Array Loop")
-　　　　　　　　　　　　　　　　
-[Next >](../repeated-substring-pattern "Repeated Substring Pattern")
-
-## [458. Poor Pigs (Hard)](https://leetcode.com/problems/poor-pigs "可怜的小猪")
-
-<p>There are <code>buckets</code> buckets of liquid, where <strong>exactly one</strong> of the buckets is poisonous. To figure out which one is poisonous, you feed some number of (poor) pigs the liquid to see whether they will die or not. Unfortunately, you only have <code>minutesToTest</code> minutes to determine which bucket is poisonous.</p>
-
-<p>You can feed the pigs according to these steps:</p>
-
-<ol>
-	<li>Choose some live pigs to feed.</li>
-	<li>For each pig, choose which buckets to feed it. The pig will consume all the chosen buckets simultaneously and will take no time.</li>
-	<li>Wait for <code>minutesToDie</code> minutes. You may <strong>not</strong> feed any other pigs during this time.</li>
-	<li>After <code>minutesToDie</code> minutes have passed, any pigs that have been fed the poisonous bucket will die, and all others will survive.</li>
-	<li>Repeat this process until you run out of time.</li>
-</ol>
-
-<p>Given <code>buckets</code>, <code>minutesToDie</code>, and <code>minutesToTest</code>, return <em>the <strong>minimum</strong> number of pigs needed to figure out which bucket is poisonous within the allotted time</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> buckets = 1000, minutesToDie = 15, minutesToTest = 60
-<strong>Output:</strong> 5
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> buckets = 4, minutesToDie = 15, minutesToTest = 15
-<strong>Output:</strong> 2
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> buckets = 4, minutesToDie = 15, minutesToTest = 30
-<strong>Output:</strong> 2
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= buckets &lt;= 1000</code></li>
-	<li><code>1 &lt;=&nbsp;minutesToDie &lt;=&nbsp;minutesToTest &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if you only have one shot? Eg. 4 buckets, 15 mins to die, and 15 mins to test.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How many states can we generate with x pigs and T tests?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Find minimum <code>x</code> such that <code>(T+1)^x >= N</code>
-</details>
diff --git a/problems/poor-pigs/poor_pigs.go b/problems/poor-pigs/poor_pigs.go
deleted file mode 100644
index 9a12f0a11..000000000
--- a/problems/poor-pigs/poor_pigs.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem458
diff --git a/problems/poor-pigs/poor_pigs_test.go b/problems/poor-pigs/poor_pigs_test.go
deleted file mode 100644
index 9a12f0a11..000000000
--- a/problems/poor-pigs/poor_pigs_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem458
diff --git a/problems/populating-next-right-pointers-in-each-node-ii/README.md b/problems/populating-next-right-pointers-in-each-node-ii/README.md
deleted file mode 100644
index 7621d80dc..000000000
--- a/problems/populating-next-right-pointers-in-each-node-ii/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../populating-next-right-pointers-in-each-node "Populating Next Right Pointers in Each Node")
-　　　　　　　　　　　　　　　　
-[Next >](../pascals-triangle "Pascal's Triangle")
-
-## [117. Populating Next Right Pointers in Each Node II (Medium)](https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii "填充每个节点的下一个右侧节点指针 II")
-
-<p>Given a binary tree</p>
-
-<pre>
-struct Node {
-  int val;
-  Node *left;
-  Node *right;
-  Node *next;
-}
-</pre>
-
-<p>Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to <code>NULL</code>.</p>
-
-<p>Initially, all next pointers are set to <code>NULL</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/15/117_sample.png" style="width: 500px; height: 171px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,null,7]
-<strong>Output:</strong> [1,#,2,3,#,4,5,7,#]
-<strong>Explanation: </strong>Given the above binary tree (Figure A), your function should populate each next pointer to point to its next right node, just like in Figure B. The serialized output is in level order as connected by the next pointers, with &#39;#&#39; signifying the end of each level.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 6000]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow-up:</strong></p>
-
-<ul>
-	<li>You may only use constant extra space.</li>
-	<li>The recursive approach is fine. You may assume implicit stack space does not count as extra space for this problem.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Populating Next Right Pointers in Each Node](../populating-next-right-pointers-in-each-node) (Medium)
diff --git a/problems/populating-next-right-pointers-in-each-node-ii/populating_next_right_pointers_in_each_node_ii.go b/problems/populating-next-right-pointers-in-each-node-ii/populating_next_right_pointers_in_each_node_ii.go
deleted file mode 100644
index c150eb655..000000000
--- a/problems/populating-next-right-pointers-in-each-node-ii/populating_next_right_pointers_in_each_node_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem117
diff --git a/problems/populating-next-right-pointers-in-each-node-ii/populating_next_right_pointers_in_each_node_ii.py b/problems/populating-next-right-pointers-in-each-node-ii/populating_next_right_pointers_in_each_node_ii.py
deleted file mode 100755
index 606b74d60..000000000
--- a/problems/populating-next-right-pointers-in-each-node-ii/populating_next_right_pointers_in_each_node_ii.py
+++ /dev/null
@@ -1,14 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a Node.
-class Node:
-    def __init__(self, val, left, right, next):
-        self.val = val
-        self.left = left
-        self.right = right
-        self.next = next
-"""
-class Solution:
-    def connect(self, root: 'Node') -> 'Node':
-        
\ No newline at end of file
diff --git a/problems/populating-next-right-pointers-in-each-node-ii/populating_next_right_pointers_in_each_node_ii_test.go b/problems/populating-next-right-pointers-in-each-node-ii/populating_next_right_pointers_in_each_node_ii_test.go
deleted file mode 100644
index c150eb655..000000000
--- a/problems/populating-next-right-pointers-in-each-node-ii/populating_next_right_pointers_in_each_node_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem117
diff --git a/problems/populating-next-right-pointers-in-each-node/README.md b/problems/populating-next-right-pointers-in-each-node/README.md
deleted file mode 100644
index e81ccb3de..000000000
--- a/problems/populating-next-right-pointers-in-each-node/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distinct-subsequences "Distinct Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../populating-next-right-pointers-in-each-node-ii "Populating Next Right Pointers in Each Node II")
-
-## [116. Populating Next Right Pointers in Each Node (Medium)](https://leetcode.com/problems/populating-next-right-pointers-in-each-node "填充每个节点的下一个右侧节点指针")
-
-<p>You are given a <strong>perfect binary tree</strong> where all leaves are on the same level, and every parent has two children. The binary tree has the following definition:</p>
-
-<pre>
-struct Node {
-  int val;
-  Node *left;
-  Node *right;
-  Node *next;
-}
-</pre>
-
-<p>Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to <code>NULL</code>.</p>
-
-<p>Initially, all next pointers are set to <code>NULL</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/14/116_sample.png" style="width: 500px; height: 171px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,6,7]
-<strong>Output:</strong> [1,#,2,3,#,4,5,6,7,#]
-<strong>Explanation: </strong>Given the above perfect binary tree (Figure A), your function should populate each next pointer to point to its next right node, just like in Figure B. The serialized output is in level order as connected by the next pointers, with &#39;#&#39; signifying the end of each level.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 2<sup>12</sup> - 1]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow-up:</strong></p>
-
-<ul>
-	<li>You may only use constant extra space.</li>
-	<li>The recursive approach is fine. You may assume implicit stack space does not count as extra space for this problem.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Populating Next Right Pointers in Each Node II](../populating-next-right-pointers-in-each-node-ii) (Medium)
-  1. [Binary Tree Right Side View](../binary-tree-right-side-view) (Medium)
diff --git a/problems/populating-next-right-pointers-in-each-node/populating_next_right_pointers_in_each_node.go b/problems/populating-next-right-pointers-in-each-node/populating_next_right_pointers_in_each_node.go
deleted file mode 100644
index 281ca015c..000000000
--- a/problems/populating-next-right-pointers-in-each-node/populating_next_right_pointers_in_each_node.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem116
diff --git a/problems/populating-next-right-pointers-in-each-node/populating_next_right_pointers_in_each_node.py b/problems/populating-next-right-pointers-in-each-node/populating_next_right_pointers_in_each_node.py
deleted file mode 100755
index 606b74d60..000000000
--- a/problems/populating-next-right-pointers-in-each-node/populating_next_right_pointers_in_each_node.py
+++ /dev/null
@@ -1,14 +0,0 @@
-#!/usr/bin/env python
-
-"""
-# Definition for a Node.
-class Node:
-    def __init__(self, val, left, right, next):
-        self.val = val
-        self.left = left
-        self.right = right
-        self.next = next
-"""
-class Solution:
-    def connect(self, root: 'Node') -> 'Node':
-        
\ No newline at end of file
diff --git a/problems/populating-next-right-pointers-in-each-node/populating_next_right_pointers_in_each_node_test.go b/problems/populating-next-right-pointers-in-each-node/populating_next_right_pointers_in_each_node_test.go
deleted file mode 100644
index 281ca015c..000000000
--- a/problems/populating-next-right-pointers-in-each-node/populating_next_right_pointers_in_each_node_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem116
diff --git a/problems/positions-of-large-groups/README.md b/problems/positions-of-large-groups/README.md
deleted file mode 100644
index 6431b0375..000000000
--- a/problems/positions-of-large-groups/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../consecutive-numbers-sum "Consecutive Numbers Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../masking-personal-information "Masking Personal Information")
-
-## [830. Positions of Large Groups (Easy)](https://leetcode.com/problems/positions-of-large-groups "较大分组的位置")
-
-<p>In a string <code><font face="monospace">s</font></code>&nbsp;of lowercase letters, these letters form consecutive groups of the same character.</p>
-
-<p>For example, a string like <code>s = &quot;abbxxxxzyy&quot;</code> has the groups <code>&quot;a&quot;</code>, <code>&quot;bb&quot;</code>, <code>&quot;xxxx&quot;</code>, <code>&quot;z&quot;</code>, and&nbsp;<code>&quot;yy&quot;</code>.</p>
-
-<p>A group is identified by an interval&nbsp;<code>[start, end]</code>, where&nbsp;<code>start</code>&nbsp;and&nbsp;<code>end</code>&nbsp;denote the start and end&nbsp;indices (inclusive) of the group. In the above example,&nbsp;<code>&quot;xxxx&quot;</code>&nbsp;has the interval&nbsp;<code>[3,6]</code>.</p>
-
-<p>A group is considered&nbsp;<strong>large</strong>&nbsp;if it has 3 or more characters.</p>
-
-<p>Return&nbsp;<em>the intervals of every <strong>large</strong> group sorted in&nbsp;<strong>increasing order by start index</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abbxxxxzzy&quot;
-<strong>Output:</strong> [[3,6]]
-<strong>Explanation</strong>: <code>&quot;xxxx&quot; is the only </code>large group with start index 3 and end index 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;
-<strong>Output:</strong> []
-<strong>Explanation</strong>: We have groups &quot;a&quot;, &quot;b&quot;, and &quot;c&quot;, none of which are large groups.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcdddeeeeaabbbcd&quot;
-<strong>Output:</strong> [[3,5],[6,9],[12,14]]
-<strong>Explanation</strong>: The large groups are &quot;ddd&quot;, &quot;eeee&quot;, and &quot;bbb&quot;.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aba&quot;
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> contains lower-case English letters only.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/positions-of-large-groups/positions_of_large_groups.go b/problems/positions-of-large-groups/positions_of_large_groups.go
deleted file mode 100644
index f9b6113aa..000000000
--- a/problems/positions-of-large-groups/positions_of_large_groups.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem830
-
-func largeGroupPositions(S string) [][]int {
-	pre, ans, l := 0, make([][]int, 0), len(S)
-	for i, v := range S {
-		if i == l-1 || v != rune(S[i+1]) {
-			if i-pre >= 2 {
-				ans = append(ans, []int{pre, i})
-			}
-			pre = i + 1
-		}
-	}
-	return ans
-}
diff --git a/problems/positions-of-large-groups/positions_of_large_groups_test.go b/problems/positions-of-large-groups/positions_of_large_groups_test.go
deleted file mode 100644
index 428224777..000000000
--- a/problems/positions-of-large-groups/positions_of_large_groups_test.go
+++ /dev/null
@@ -1,46 +0,0 @@
-package problem830
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   string
-	want [][]int
-}
-
-func TestLargeGroupPositions(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: "abbxxxxzzy",
-			want: [][]int{
-				{3, 6},
-			},
-		},
-		{
-			in:   "abc",
-			want: [][]int{},
-		},
-		{
-			in: "abcdddeeeeaabbbcd",
-			want: [][]int{
-				{3, 5},
-				{6, 9},
-				{12, 14},
-			},
-		},
-		{
-			in: "abcddd",
-			want: [][]int{
-				{3, 5},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := largeGroupPositions(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/possible-bipartition/README.md b/problems/possible-bipartition/README.md
deleted file mode 100644
index d37d11381..000000000
--- a/problems/possible-bipartition/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../spiral-matrix-iii "Spiral Matrix III")
-　　　　　　　　　　　　　　　　
-[Next >](../super-egg-drop "Super Egg Drop")
-
-## [886. Possible Bipartition (Medium)](https://leetcode.com/problems/possible-bipartition "可能的二分法")
-
-<p>We want to split a group of <code>n</code> people (labeled from <code>1</code> to <code>n</code>) into two groups of <strong>any size</strong>. Each person may dislike some other people, and they should not go into the same group.</p>
-
-<p>Given the integer <code>n</code> and the array <code>dislikes</code> where <code>dislikes[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that the person labeled <code>a<sub>i</sub></code> does not like the person labeled <code>b<sub>i</sub></code>, return <code>true</code> <em>if it is possible to split everyone into two groups in this way</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, dislikes = [[1,2],[1,3],[2,4]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> group1 [1,4] and group2 [2,3].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, dislikes = [[1,2],[1,3],[2,3]]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, dislikes = [[1,2],[2,3],[3,4],[4,5],[1,5]]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 2000</code></li>
-	<li><code>0 &lt;= dislikes.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>dislikes[i].length == 2</code></li>
-	<li><code>1 &lt;= dislikes[i][j] &lt;= n</code></li>
-	<li><code>a<sub>i</sub> &lt; b<sub>i</sub></code></li>
-	<li>All the pairs of <code>dislikes</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
diff --git a/problems/possible-bipartition/possible_bipartition.go b/problems/possible-bipartition/possible_bipartition.go
deleted file mode 100644
index 793dca90c..000000000
--- a/problems/possible-bipartition/possible_bipartition.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem886
diff --git a/problems/possible-bipartition/possible_bipartition_test.go b/problems/possible-bipartition/possible_bipartition_test.go
deleted file mode 100644
index 793dca90c..000000000
--- a/problems/possible-bipartition/possible_bipartition_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem886
diff --git a/problems/pour-water-between-buckets-to-make-water-levels-equal/README.md b/problems/pour-water-between-buckets-to-make-water-levels-equal/README.md
deleted file mode 100644
index 3c977e969..000000000
--- a/problems/pour-water-between-buckets-to-make-water-levels-equal/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../earliest-possible-day-of-full-bloom "Earliest Possible Day of Full Bloom")
-　　　　　　　　　　　　　　　　
-[Next >](../divide-a-string-into-groups-of-size-k "Divide a String Into Groups of Size k")
-
-## [2137. Pour Water Between Buckets to Make Water Levels Equal (Medium)](https://leetcode.com/problems/pour-water-between-buckets-to-make-water-levels-equal "")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What is the range that the answer must fall into?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The answer has to be in the range [0, max(buckets)] (inclusive).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For a number x, is there an efficient way to check if it is possible to make the amount of water in each bucket x.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Let in be the total amount of water that needs to be poured into buckets and out be the total amount of water that needs to be poured out of buckets to make the amount of water in each bucket x. If out - (out * loss) >= in, then it is possible.
-</details>
diff --git a/problems/pour-water/README.md b/problems/pour-water/README.md
deleted file mode 100644
index 5cb10675a..000000000
--- a/problems/pour-water/README.md
+++ /dev/null
@@ -1,143 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reach-a-number "Reach a Number")
-　　　　　　　　　　　　　　　　
-[Next >](../pyramid-transition-matrix "Pyramid Transition Matrix")
-
-## [755. Pour Water (Medium)](https://leetcode.com/problems/pour-water "倒水")
-
-<p>
-We are given an elevation map, <code>heights[i]</code> representing the height of the terrain at that index.  The width at each index is 1.  After <code>V</code> units of water fall at index <code>K</code>, how much water is at each index?
-</p><p>
-Water first drops at index <code>K</code> and rests on top of the highest terrain or water at that index.  Then, it flows according to the following rules:
-<li>If the droplet would eventually fall by moving left, then move left.</li>
-<li>Otherwise, if the droplet would eventually fall by moving right, then move right.</li>
-<li>Otherwise, rise at it's current position.</li>
-Here, "eventually fall" means that the droplet will eventually be at a lower level if it moves in that direction.
-Also, "level" means the height of the terrain plus any water in that column.
-</p><p>
-We can assume there's infinitely high terrain on the two sides out of bounds of the array.  Also, there could not be partial water being spread out evenly on more than 1 grid block - each unit of water has to be in exactly one block.
-<p>
-
-<p><b>Example 1:</b><br />
-<pre>
-<b>Input:</b> heights = [2,1,1,2,1,2,2], V = 4, K = 3
-<b>Output:</b> [2,2,2,3,2,2,2]
-<b>Explanation:</b>
-#       #
-#       #
-##  # ###
-#########
- 0123456    <- index
-
-The first drop of water lands at index K = 3:
-
-#       #
-#   w   #
-##  # ###
-#########
- 0123456    
-
-When moving left or right, the water can only move to the same level or a lower level.
-(By level, we mean the total height of the terrain plus any water in that column.)
-Since moving left will eventually make it fall, it moves left.
-(A droplet "made to fall" means go to a lower height than it was at previously.)
-
-#       #
-#       #
-## w# ###
-#########
- 0123456    
-
-Since moving left will not make it fall, it stays in place.  The next droplet falls:
-
-#       #
-#   w   #
-## w# ###
-#########
- 0123456  
-
-Since the new droplet moving left will eventually make it fall, it moves left.
-Notice that the droplet still preferred to move left,
-even though it could move right (and moving right makes it fall quicker.)
-
-#       #
-#  w    #
-## w# ###
-#########
- 0123456  
-
-#       #
-#       #
-##ww# ###
-#########
- 0123456  
-
-After those steps, the third droplet falls.
-Since moving left would not eventually make it fall, it tries to move right.
-Since moving right would eventually make it fall, it moves right.
-
-#       #
-#   w   #
-##ww# ###
-#########
- 0123456  
-
-#       #
-#       #
-##ww#w###
-#########
- 0123456  
-
-Finally, the fourth droplet falls.
-Since moving left would not eventually make it fall, it tries to move right.
-Since moving right would not eventually make it fall, it stays in place:
-
-#       #
-#   w   #
-##ww#w###
-#########
- 0123456  
-
-The final answer is [2,2,2,3,2,2,2]:
-
-    #    
- ####### 
- ####### 
- 0123456 
-</pre>
-</p>
-
-<p><b>Example 2:</b><br />
-<pre>
-<b>Input:</b> heights = [1,2,3,4], V = 2, K = 2
-<b>Output:</b> [2,3,3,4]
-<b>Explanation:</b>
-The last droplet settles at index 1, since moving further left would not cause it to eventually fall to a lower height.
-</pre>
-</p>
-
-<p><b>Example 3:</b><br />
-<pre>
-<b>Input:</b> heights = [3,1,3], V = 5, K = 1
-<b>Output:</b> [4,4,4]
-</pre>
-</p>
-
-<p><b>Note:</b><br><ol>
-<li><code>heights</code> will have length in <code>[1, 100]</code> and contain integers in <code>[0, 99]</code>.</li>
-<li><code>V</code> will be in range <code>[0, 2000]</code>.</li>
-<li><code>K</code> will be in range <code>[0, heights.length - 1]</code>.</li>
-</ol></p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Trapping Rain Water](../trapping-rain-water) (Hard)
diff --git a/problems/pour-water/pour_water.go b/problems/pour-water/pour_water.go
deleted file mode 100644
index 3191853a0..000000000
--- a/problems/pour-water/pour_water.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem755
diff --git a/problems/pour-water/pour_water_test.go b/problems/pour-water/pour_water_test.go
deleted file mode 100644
index 3191853a0..000000000
--- a/problems/pour-water/pour_water_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem755
diff --git a/problems/power-of-four/README.md b/problems/power-of-four/README.md
deleted file mode 100644
index 925cd1c2b..000000000
--- a/problems/power-of-four/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flatten-nested-list-iterator "Flatten Nested List Iterator")
-　　　　　　　　　　　　　　　　
-[Next >](../integer-break "Integer Break")
-
-## [342. Power of Four (Easy)](https://leetcode.com/problems/power-of-four "4的幂")
-
-<p>Given an integer <code>n</code>, return <em><code>true</code> if it is a power of four. Otherwise, return <code>false</code></em>.</p>
-
-<p>An integer <code>n</code> is a power of four, if there exists an integer <code>x</code> such that <code>n == 4<sup>x</sup></code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 16
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 5
-<strong>Output:</strong> false
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> n = 1
-<strong>Output:</strong> true
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you solve it without loops/recursion?
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Power of Two](../power-of-two) (Easy)
-  1. [Power of Three](../power-of-three) (Easy)
diff --git a/problems/power-of-four/power_of_four.go b/problems/power-of-four/power_of_four.go
deleted file mode 100644
index f60b52557..000000000
--- a/problems/power-of-four/power_of_four.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem342
-
-func isPowerOfFour(num int) bool {
-	return num&(num-1) == 0 && num&0x55555555 > 0
-}
diff --git a/problems/power-of-four/power_of_four_test.go b/problems/power-of-four/power_of_four_test.go
deleted file mode 100644
index aaaa15ddf..000000000
--- a/problems/power-of-four/power_of_four_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem342
-
-import "testing"
-
-type testType struct {
-	in   int
-	want bool
-}
-
-func TestIsPowerOfFour(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   16,
-			want: true,
-		},
-		{
-			in:   5,
-			want: false,
-		},
-		{
-			in:   6,
-			want: false,
-		},
-		{
-			in:   12,
-			want: false,
-		},
-		{
-			in:   0,
-			want: false,
-		},
-		{
-			in:   1,
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := isPowerOfFour(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/power-of-three/README.md b/problems/power-of-three/README.md
deleted file mode 100644
index 1f77942fa..000000000
--- a/problems/power-of-three/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-size-subarray-sum-equals-k "Maximum Size Subarray Sum Equals k")
-　　　　　　　　　　　　　　　　
-[Next >](../count-of-range-sum "Count of Range Sum")
-
-## [326. Power of Three (Easy)](https://leetcode.com/problems/power-of-three "3 的幂")
-
-<p>Given an integer <code>n</code>, return <em><code>true</code> if it is a power of three. Otherwise, return <code>false</code></em>.</p>
-
-<p>An integer <code>n</code> is a power of three, if there exists an integer <code>x</code> such that <code>n == 3<sup>x</sup></code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 27
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 0
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 9
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you solve it without loops/recursion?
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Power of Two](../power-of-two) (Easy)
-  1. [Power of Four](../power-of-four) (Easy)
diff --git a/problems/power-of-three/power_of_three.go b/problems/power-of-three/power_of_three.go
deleted file mode 100644
index cd21cd948..000000000
--- a/problems/power-of-three/power_of_three.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem326
-
-func isPowerOfThree(n int) bool {
-	return n > 0 && 1162261467%n == 0
-}
diff --git a/problems/power-of-three/power_of_three_test.go b/problems/power-of-three/power_of_three_test.go
deleted file mode 100644
index b889dfde8..000000000
--- a/problems/power-of-three/power_of_three_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem326
-
-import "testing"
-
-type testType struct {
-	in   int
-	want bool
-}
-
-func TestIsPowerOfThree(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   27,
-			want: true,
-		},
-		{
-			in:   0,
-			want: false,
-		},
-		{
-			in:   1,
-			want: true,
-		},
-		{
-			in:   9,
-			want: true,
-		},
-		{
-			in:   45,
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isPowerOfThree(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/power-of-two/README.md b/problems/power-of-two/README.md
deleted file mode 100644
index 8967dc809..000000000
--- a/problems/power-of-two/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-smallest-element-in-a-bst "Kth Smallest Element in a BST")
-　　　　　　　　　　　　　　　　
-[Next >](../implement-queue-using-stacks "Implement Queue using Stacks")
-
-## [231. Power of Two (Easy)](https://leetcode.com/problems/power-of-two "2 的幂")
-
-<p>Given an integer <code>n</code>, return <em><code>true</code> if it is a power of two. Otherwise, return <code>false</code></em>.</p>
-
-<p>An integer <code>n</code> is a power of two, if there exists an integer <code>x</code> such that <code>n == 2<sup>x</sup></code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> true
-<strong>Explanation: </strong>2<sup>0</sup> = 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 16
-<strong>Output:</strong> true
-<strong>Explanation: </strong>2<sup>4</sup> = 16
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you solve it without loops/recursion?
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Number of 1 Bits](../number-of-1-bits) (Easy)
-  1. [Power of Three](../power-of-three) (Easy)
-  1. [Power of Four](../power-of-four) (Easy)
diff --git a/problems/power-of-two/power_of_two.go b/problems/power-of-two/power_of_two.go
deleted file mode 100644
index a69576fe5..000000000
--- a/problems/power-of-two/power_of_two.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem231
-
-func isPowerOfTwo(n int) bool {
-	return n > 0 && n&(n-1) == 0
-}
diff --git a/problems/power-of-two/power_of_two_test.go b/problems/power-of-two/power_of_two_test.go
deleted file mode 100644
index dce162355..000000000
--- a/problems/power-of-two/power_of_two_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem231
-
-import "testing"
-
-type testType struct {
-	in   int
-	want bool
-}
-
-func TestIsPowerOfTwo(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   0,
-			want: false,
-		},
-		{
-			in:   1,
-			want: true,
-		},
-		{
-			in:   12,
-			want: false,
-		},
-		{
-			in:   16,
-			want: true,
-		},
-		{
-			in:   218,
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isPowerOfTwo(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/powerful-integers/README.md b/problems/powerful-integers/README.md
deleted file mode 100644
index 92b9a3fc2..000000000
--- a/problems/powerful-integers/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pancake-sorting "Pancake Sorting")
-　　　　　　　　　　　　　　　　
-[Next >](../flip-binary-tree-to-match-preorder-traversal "Flip Binary Tree To Match Preorder Traversal")
-
-## [970. Powerful Integers (Medium)](https://leetcode.com/problems/powerful-integers "强整数")
-
-<p>Given three integers <code>x</code>, <code>y</code>, and <code>bound</code>, return <em>a list of all the <strong>powerful integers</strong> that have a value less than or equal to</em> <code>bound</code>.</p>
-
-<p>An integer is <strong>powerful</strong> if it can be represented as <code>x<sup>i</sup> + y<sup>j</sup></code> for some integers <code>i &gt;= 0</code> and <code>j &gt;= 0</code>.</p>
-
-<p>You may return the answer in <strong>any order</strong>. In your answer, each value should occur <strong>at most once</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 2, y = 3, bound = 10
-<strong>Output:</strong> [2,3,4,5,7,9,10]
-<strong>Explanation:</strong>
-2 = 2<sup>0</sup> + 3<sup>0</sup>
-3 = 2<sup>1</sup> + 3<sup>0</sup>
-4 = 2<sup>0</sup> + 3<sup>1</sup>
-5 = 2<sup>1</sup> + 3<sup>1</sup>
-7 = 2<sup>2</sup> + 3<sup>1</sup>
-9 = 2<sup>3</sup> + 3<sup>0</sup>
-10 = 2<sup>0</sup> + 3<sup>2</sup>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 3, y = 5, bound = 15
-<strong>Output:</strong> [2,4,6,8,10,14]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= x, y &lt;= 100</code></li>
-	<li><code>0 &lt;= bound &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/powerful-integers/powerful_integers.go b/problems/powerful-integers/powerful_integers.go
deleted file mode 100644
index c2b631f2a..000000000
--- a/problems/powerful-integers/powerful_integers.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem970
-
-import "math"
-
-func powerfulIntegers(x int, y int, bound int) []int {
-	xFloat, yFloat, boundFloat := float64(x), float64(y), float64(bound)
-	ans, m := make([]int, 0), make(map[float64]bool)
-	for i := 0.0; i < 18 && math.Pow(xFloat, i) <= boundFloat; i++ {
-		for j := 0.0; j < 18 && math.Pow(yFloat, j) <= boundFloat; j++ {
-			if v := math.Pow(xFloat, i) + math.Pow(yFloat, j); v <= boundFloat && !m[v] {
-				ans, m[v] = append(ans, int(v)), true
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/powerful-integers/powerful_integers_test.go b/problems/powerful-integers/powerful_integers_test.go
deleted file mode 100644
index 6fa8ef17c..000000000
--- a/problems/powerful-integers/powerful_integers_test.go
+++ /dev/null
@@ -1,37 +0,0 @@
-package problem970
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	x     int
-	y     int
-	bound int
-	want  []int
-}
-
-func TestPowerfulIntegers(t *testing.T) {
-	tests := [...]testType{
-		{
-			x:     2,
-			y:     3,
-			bound: 10,
-			want:  []int{2, 3, 4, 5, 7, 9, 10},
-		},
-		{
-			x:     3,
-			y:     5,
-			bound: 15,
-			want:  []int{2, 4, 6, 8, 10, 14},
-		},
-	}
-	for _, tt := range tests {
-		got := powerfulIntegers(tt.x, tt.y, tt.bound)
-		if !kit.IsEqualSliceInt(got, tt.want) {
-			t.Fatalf("in: %v %v %v, got: %v, want: %v", tt.x, tt.y, tt.bound, got, tt.want)
-		}
-	}
-}
diff --git a/problems/powx-n/README.md b/problems/powx-n/README.md
deleted file mode 100644
index b16dbab50..000000000
--- a/problems/powx-n/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../group-anagrams "Group Anagrams")
-　　　　　　　　　　　　　　　　
-[Next >](../n-queens "N-Queens")
-
-## [50. Pow(x, n) (Medium)](https://leetcode.com/problems/powx-n "Pow(x, n)")
-
-<p>Implement <a href="http://www.cplusplus.com/reference/valarray/pow/" target="_blank">pow(x, n)</a>, which calculates <code>x</code> raised to the power <code>n</code> (i.e., <code>x<sup>n</sup></code>).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 2.00000, n = 10
-<strong>Output:</strong> 1024.00000
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 2.10000, n = 3
-<strong>Output:</strong> 9.26100
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 2.00000, n = -2
-<strong>Output:</strong> 0.25000
-<strong>Explanation:</strong> 2<sup>-2</sup> = 1/2<sup>2</sup> = 1/4 = 0.25
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-100.0 &lt;&nbsp;x&nbsp;&lt; 100.0</code></li>
-	<li><code>-2<sup>31</sup>&nbsp;&lt;= n &lt;=&nbsp;2<sup>31</sup>-1</code></li>
-	<li><code>-10<sup>4</sup> &lt;= x<sup>n</sup> &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Sqrt(x)](../sqrtx) (Easy)
-  1. [Super Pow](../super-pow) (Medium)
diff --git a/problems/powx-n/powx_n.go b/problems/powx-n/powx_n.go
deleted file mode 100644
index 424d20f56..000000000
--- a/problems/powx-n/powx_n.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem50
-
-func myPow(x float64, n int) float64 {
-	res := 1.0
-	if n < 0 {
-		n = -n
-		x = 1 / x
-	}
-	for ; n > 0; n >>= 1 {
-		if n&1 == 1 {
-			res *= x
-		}
-		x *= x
-	}
-	return res
-}
diff --git a/problems/powx-n/powx_n_test.go b/problems/powx-n/powx_n_test.go
deleted file mode 100644
index 52082d715..000000000
--- a/problems/powx-n/powx_n_test.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package problem50
-
-import (
-	"math"
-	"testing"
-)
-
-type testType struct {
-	x    float64
-	n    int
-	want float64
-}
-
-func TestMyPow(t *testing.T) {
-	tests := [...]testType{
-		{
-			x:    2.00000,
-			n:    10,
-			want: 1024.00000,
-		},
-		{
-			x:    2.10000,
-			n:    3,
-			want: 9.26100,
-		},
-		{
-			x:    2.00000,
-			n:    -2,
-			want: 0.25000,
-		},
-	}
-
-	for _, tt := range tests {
-		got := myPow(tt.x, tt.n)
-		got = math.Trunc(got*1e5) / 1e5
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.x, tt.n, got, tt.want)
-		}
-	}
-}
diff --git a/problems/predict-the-winner/README.md b/problems/predict-the-winner/README.md
deleted file mode 100644
index 4e364f34e..000000000
--- a/problems/predict-the-winner/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-consecutive-ones "Max Consecutive Ones")
-　　　　　　　　　　　　　　　　
-[Next >](../max-consecutive-ones-ii "Max Consecutive Ones II")
-
-## [486. Predict the Winner (Medium)](https://leetcode.com/problems/predict-the-winner "预测赢家")
-
-<p>You are given an integer array <code>nums</code>. Two players are playing a game with this array: player 1 and player 2.</p>
-
-<p>Player 1 and player 2 take turns, with player 1 starting first. Both players start the game with a score of <code>0</code>. At each turn, the player takes one of the numbers from either end of the array (i.e., <code>nums[0]</code> or <code>nums[nums.length - 1]</code>) which reduces the size of the array by <code>1</code>. The player adds the chosen number to their score. The game ends when there are no more elements in the array.</p>
-
-<p>Return <code>true</code> if Player 1 can win the game. If the scores of both players are equal, then player 1 is still the winner, and you should also return <code>true</code>. You may assume that both players are playing optimally.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5,2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Initially, player 1 can choose between 1 and 2. 
-If he chooses 2 (or 1), then player 2 can choose from 1 (or 2) and 5. If player 2 chooses 5, then player 1 will be left with 1 (or 2). 
-So, final score of player 1 is 1 + 2 = 3, and player 2 is 5. 
-Hence, player 1 will never be the winner and you need to return false.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5,233,7]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Player 1 first chooses 1. Then player 2 has to choose between 5 and 7. No matter which number player 2 choose, player 1 can choose 233.
-Finally, player 1 has more score (234) than player 2 (12), so you need to return True representing player1 can win.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 20</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Similar Questions
-  1. [Can I Win](../can-i-win) (Medium)
diff --git a/problems/predict-the-winner/predict_the_winner.go b/problems/predict-the-winner/predict_the_winner.go
deleted file mode 100644
index b0cc37096..000000000
--- a/problems/predict-the-winner/predict_the_winner.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem486
diff --git a/problems/predict-the-winner/predict_the_winner_test.go b/problems/predict-the-winner/predict_the_winner_test.go
deleted file mode 100644
index b0cc37096..000000000
--- a/problems/predict-the-winner/predict_the_winner_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem486
diff --git a/problems/prefix-and-suffix-search/README.md b/problems/prefix-and-suffix-search/README.md
deleted file mode 100644
index e420268da..000000000
--- a/problems/prefix-and-suffix-search/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-smallest-letter-greater-than-target "Find Smallest Letter Greater Than Target")
-　　　　　　　　　　　　　　　　
-[Next >](../min-cost-climbing-stairs "Min Cost Climbing Stairs")
-
-## [745. Prefix and Suffix Search (Hard)](https://leetcode.com/problems/prefix-and-suffix-search "前缀和后缀搜索")
-
-<p>Design a special dictionary with some words that searchs the words in it by a prefix and a suffix.</p>
-
-<p>Implement the <code>WordFilter</code> class:</p>
-
-<ul>
-	<li><code>WordFilter(string[] words)</code> Initializes the object with the <code>words</code> in the dictionary.</li>
-	<li><code>f(string prefix, string suffix)</code> Returns <em>the index of the word in the dictionary,</em> which has the prefix <code>prefix</code> and the suffix <code>suffix</code>. If there is more than one valid index, return <strong>the largest</strong> of them. If there is no such word in the dictionary, return <code>-1</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;WordFilter&quot;, &quot;f&quot;]
-[[[&quot;apple&quot;]], [&quot;a&quot;, &quot;e&quot;]]
-<strong>Output</strong>
-[null, 0]
-
-<strong>Explanation</strong>
-WordFilter wordFilter = new WordFilter([&quot;apple&quot;]);
-wordFilter.f(&quot;a&quot;, &quot;e&quot;); // return 0, because the word at index 0 has prefix = &quot;a&quot; and suffix = &#39;e&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 15000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 10</code></li>
-	<li><code>1 &lt;= prefix.length, suffix.length &lt;= 10</code></li>
-	<li><code>words[i]</code>, <code>prefix</code> and <code>suffix</code> consist of lower-case English letters only.</li>
-	<li>At most <code>15000</code> calls will be made to the function <code>f</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Design Add and Search Words Data Structure](../design-add-and-search-words-data-structure) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For a word like "test", consider "#test", "t#test", "st#test", "est#test", "test#test".  Then if we have a query like prefix = "te", suffix = "t", we can find it by searching for something we've inserted starting with "t#te".
-</details>
diff --git a/problems/prefix-and-suffix-search/prefix_and_suffix_search.go b/problems/prefix-and-suffix-search/prefix_and_suffix_search.go
deleted file mode 100644
index 0e8ee2555..000000000
--- a/problems/prefix-and-suffix-search/prefix_and_suffix_search.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem745
diff --git a/problems/prefix-and-suffix-search/prefix_and_suffix_search_test.go b/problems/prefix-and-suffix-search/prefix_and_suffix_search_test.go
deleted file mode 100644
index 0e8ee2555..000000000
--- a/problems/prefix-and-suffix-search/prefix_and_suffix_search_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem745
diff --git a/problems/preimage-size-of-factorial-zeroes-function/README.md b/problems/preimage-size-of-factorial-zeroes-function/README.md
deleted file mode 100644
index dc4e6827d..000000000
--- a/problems/preimage-size-of-factorial-zeroes-function/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-matching-subsequences "Number of Matching Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-tic-tac-toe-state "Valid Tic-Tac-Toe State")
-
-## [793. Preimage Size of Factorial Zeroes Function (Hard)](https://leetcode.com/problems/preimage-size-of-factorial-zeroes-function "阶乘函数后 K 个零")
-
-<p>Let <code>f(x)</code> be the number of zeroes at the end of <code>x!</code>. Recall that <code>x! = 1 * 2 * 3 * ... * x</code> and by convention, <code>0! = 1</code>.</p>
-
-<ul>
-	<li>For example, <code>f(3) = 0</code> because <code>3! = 6</code> has no zeroes at the end, while <code>f(11) = 2</code> because <code>11! = 39916800</code> has two zeroes at the end.</li>
-</ul>
-
-<p>Given an integer <code>k</code>, return the number of non-negative integers <code>x</code> have the property that <code>f(x) = k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 0
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> 0!, 1!, 2!, 3!, and 4! end with k = 0 zeroes.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 5
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no x such that x! ends in k = 5 zeroes.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3
-<strong>Output:</strong> 5
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= k &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Factorial Trailing Zeroes](../factorial-trailing-zeroes) (Medium)
diff --git a/problems/preimage-size-of-factorial-zeroes-function/preimage_size_of_factorial_zeroes_function.go b/problems/preimage-size-of-factorial-zeroes-function/preimage_size_of_factorial_zeroes_function.go
deleted file mode 100644
index b734faf1a..000000000
--- a/problems/preimage-size-of-factorial-zeroes-function/preimage_size_of_factorial_zeroes_function.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package problem793
-
-func preimageSizeFZF(K int) int {
-	l, r := 0, 5*(K+1)
-	for l <= r {
-		m := l + (r-l)/2
-		km := zeros(m)
-		if km < K {
-			l = m + 1
-		} else if km > K {
-			r = m - 1
-		} else {
-			return 5
-		}
-	}
-	return 0
-}
-
-func zeros(x int) int {
-	r := 0
-	for x > 0 {
-		r += x / 5
-		x /= 5
-	}
-	return r
-}
diff --git a/problems/preimage-size-of-factorial-zeroes-function/preimage_size_of_factorial_zeroes_function_test.go b/problems/preimage-size-of-factorial-zeroes-function/preimage_size_of_factorial_zeroes_function_test.go
deleted file mode 100644
index 713f17821..000000000
--- a/problems/preimage-size-of-factorial-zeroes-function/preimage_size_of_factorial_zeroes_function_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem793
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestPreimageSizeFZF(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   0,
-			want: 5,
-		},
-		{
-			in:   5,
-			want: 0,
-		},
-		{
-			in:   17,
-			want: 0,
-		},
-		{
-			in:   11,
-			want: 0,
-		},
-	}
-	for _, tt := range tests {
-		got := preimageSizeFZF(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/previous-permutation-with-one-swap/README.md b/problems/previous-permutation-with-one-swap/README.md
deleted file mode 100644
index 34691ac25..000000000
--- a/problems/previous-permutation-with-one-swap/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../grumpy-bookstore-owner "Grumpy Bookstore Owner")
-　　　　　　　　　　　　　　　　
-[Next >](../distant-barcodes "Distant Barcodes")
-
-## [1053. Previous Permutation With One Swap (Medium)](https://leetcode.com/problems/previous-permutation-with-one-swap "交换一次的先前排列")
-
-<p>Given an array of positive integers <code>arr</code> (not necessarily distinct), return <em>the lexicographically largest permutation that is smaller than</em> <code>arr</code>, that can be <strong>made with exactly one swap</strong> (A <em>swap</em> exchanges the positions of two numbers <code>arr[i]</code> and <code>arr[j]</code>). If it cannot be done, then return the same array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,2,1]
-<strong>Output:</strong> [3,1,2]
-<strong>Explanation:</strong> Swapping 2 and 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,1,5]
-<strong>Output:</strong> [1,1,5]
-<strong>Explanation:</strong> This is already the smallest permutation.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,9,4,6,7]
-<strong>Output:</strong> [1,7,4,6,9]
-<strong>Explanation:</strong> Swapping 9 and 7.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,1,1,3]
-<strong>Output:</strong> [1,3,1,3]
-<strong>Explanation:</strong> Swapping 1 and 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You need to swap two values, one larger than the other.  Where is the larger one located?
-</details>
diff --git a/problems/previous-permutation-with-one-swap/previous_permutation_with_one_swap.go b/problems/previous-permutation-with-one-swap/previous_permutation_with_one_swap.go
deleted file mode 100644
index 342701569..000000000
--- a/problems/previous-permutation-with-one-swap/previous_permutation_with_one_swap.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem1053
-
-func prevPermOpt1(A []int) []int {
-	n := len(A)
-	stack, top := make([]int, n), 0
-	stack[top] = n - 1
-
-	for i := n - 2; i >= 0; i-- {
-		if A[i] <= A[stack[top]] {
-			top++
-			stack[top] = i
-			continue
-		}
-		for top-1 >= 0 &&
-			A[stack[top]] < A[stack[top-1]] &&
-			A[stack[top-1]] < A[i] {
-			top--
-		}
-		j := stack[top]
-		A[i], A[j] = A[j], A[i]
-		break
-	}
-
-	return A
-}
diff --git a/problems/primary-department-for-each-employee/README.md b/problems/primary-department-for-each-employee/README.md
deleted file mode 100644
index cbceac426..000000000
--- a/problems/primary-department-for-each-employee/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximize-the-beauty-of-the-garden "Maximize the Beauty of the Garden")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-one-string-swap-can-make-strings-equal "Check if One String Swap Can Make Strings Equal")
-
-## [1789. Primary Department for Each Employee (Easy)](https://leetcode.com/problems/primary-department-for-each-employee "员工的直属部门")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/primary-department-for-each-employee/mysql_schemas.sql b/problems/primary-department-for-each-employee/mysql_schemas.sql
deleted file mode 100644
index bae508bb0..000000000
--- a/problems/primary-department-for-each-employee/mysql_schemas.sql
+++ /dev/null
@@ -1,9 +0,0 @@
-Create table If Not Exists Employee (employee_id int, department_id int, primary_flag ENUM('Y','N'));
-Truncate table Employee;
-insert into Employee (employee_id, department_id, primary_flag) values ('1', '1', 'N');
-insert into Employee (employee_id, department_id, primary_flag) values ('2', '1', 'Y');
-insert into Employee (employee_id, department_id, primary_flag) values ('2', '2', 'N');
-insert into Employee (employee_id, department_id, primary_flag) values ('3', '3', 'N');
-insert into Employee (employee_id, department_id, primary_flag) values ('4', '2', 'N');
-insert into Employee (employee_id, department_id, primary_flag) values ('4', '3', 'Y');
-insert into Employee (employee_id, department_id, primary_flag) values ('4', '4', 'N');
diff --git a/problems/prime-arrangements/README.md b/problems/prime-arrangements/README.md
deleted file mode 100644
index bb7caddf2..000000000
--- a/problems/prime-arrangements/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../immediate-food-delivery-ii "Immediate Food Delivery II")
-　　　　　　　　　　　　　　　　
-[Next >](../diet-plan-performance "Diet Plan Performance")
-
-## [1175. Prime Arrangements (Easy)](https://leetcode.com/problems/prime-arrangements "质数排列")
-
-<p>Return the number of permutations of 1 to <code>n</code> so that prime numbers are at prime indices (1-indexed.)</p>
-
-<p><em>(Recall that an integer&nbsp;is prime if and only if it is greater than 1, and cannot be written as a product of two positive integers&nbsp;both smaller than it.)</em></p>
-
-<p>Since the answer may be large, return the answer <strong>modulo <code>10^9 + 7</code></strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> For example [1,2,5,4,3] is a valid permutation, but [5,2,3,4,1] is not because the prime number 5 is at index 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 100
-<strong>Output:</strong> 682289015
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Solve the problem for prime numbers and composite numbers separately.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Multiply the number of permutations of prime numbers over prime indices with the number of permutations of composite numbers over composite indices.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The number of permutations equals the factorial.
-</details>
diff --git a/problems/prime-number-of-set-bits-in-binary-representation/README.md b/problems/prime-number-of-set-bits-in-binary-representation/README.md
deleted file mode 100644
index 8cc15c482..000000000
--- a/problems/prime-number-of-set-bits-in-binary-representation/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../special-binary-string "Special Binary String")
-　　　　　　　　　　　　　　　　
-[Next >](../partition-labels "Partition Labels")
-
-## [762. Prime Number of Set Bits in Binary Representation (Easy)](https://leetcode.com/problems/prime-number-of-set-bits-in-binary-representation "二进制表示中质数个计算置位")
-
-<p>Given two integers <code>left</code> and <code>right</code>, return <em>the <strong>count</strong> of numbers in the <strong>inclusive</strong> range </em><code>[left, right]</code><em> having a <strong>prime number of set bits</strong> in their binary representation</em>.</p>
-
-<p>Recall that the <strong>number of set bits</strong> an integer has is the number of <code>1</code>&#39;s present when written in binary.</p>
-
-<ul>
-	<li>For example, <code>21</code> written in binary is <code>10101</code>, which has <code>3</code> set bits.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = 6, right = 10
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>
-6  -&gt; 110 (2 set bits, 2 is prime)
-7  -&gt; 111 (3 set bits, 3 is prime)
-8  -&gt; 1000 (1 set bit, 1 is not prime)
-9  -&gt; 1001 (2 set bits, 2 is prime)
-10 -&gt; 1010 (2 set bits, 2 is prime)
-4 numbers have a prime number of set bits.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = 10, right = 15
-<strong>Output:</strong> 5
-<strong>Explanation:</strong>
-10 -&gt; 1010 (2 set bits, 2 is prime)
-11 -&gt; 1011 (3 set bits, 3 is prime)
-12 -&gt; 1100 (2 set bits, 2 is prime)
-13 -&gt; 1101 (3 set bits, 3 is prime)
-14 -&gt; 1110 (3 set bits, 3 is prime)
-15 -&gt; 1111 (4 set bits, 4 is not prime)
-5 numbers have a prime number of set bits.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= left &lt;= right &lt;= 10<sup>6</sup></code></li>
-	<li><code>0 &lt;= right - left &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Number of 1 Bits](../number-of-1-bits) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Write a helper function to count the number of set bits in a number, then check whether the number of set bits is 2, 3, 5, 7, 11, 13, 17 or 19.
-</details>
diff --git a/problems/prime-number-of-set-bits-in-binary-representation/prime_number_of_set_bits_in_binary_representation.go b/problems/prime-number-of-set-bits-in-binary-representation/prime_number_of_set_bits_in_binary_representation.go
deleted file mode 100644
index 6e28fe692..000000000
--- a/problems/prime-number-of-set-bits-in-binary-representation/prime_number_of_set_bits_in_binary_representation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem762
diff --git a/problems/prime-number-of-set-bits-in-binary-representation/prime_number_of_set_bits_in_binary_representation_test.go b/problems/prime-number-of-set-bits-in-binary-representation/prime_number_of_set_bits_in_binary_representation_test.go
deleted file mode 100644
index 6e28fe692..000000000
--- a/problems/prime-number-of-set-bits-in-binary-representation/prime_number_of_set_bits_in_binary_representation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem762
diff --git a/problems/prime-palindrome/README.md b/problems/prime-palindrome/README.md
deleted file mode 100644
index 6a821c8e6..000000000
--- a/problems/prime-palindrome/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-subtree-with-all-the-deepest-nodes "Smallest Subtree with all the Deepest Nodes")
-　　　　　　　　　　　　　　　　
-[Next >](../transpose-matrix "Transpose Matrix")
-
-## [866. Prime Palindrome (Medium)](https://leetcode.com/problems/prime-palindrome "回文素数")
-
-<p>Given an integer n, return <em>the smallest <strong>prime palindrome</strong> greater than or equal to </em><code>n</code>.</p>
-
-<p>An integer is <strong>prime</strong> if it has exactly two divisors: <code>1</code> and itself. Note that <code>1</code> is not a prime number.</p>
-
-<ul>
-	<li>For example, <code>2</code>, <code>3</code>, <code>5</code>, <code>7</code>, <code>11</code>, and <code>13</code> are all primes.</li>
-</ul>
-
-<p>An integer is a <strong>palindrome</strong> if it reads the same from left to right as it does from right to left.</p>
-
-<ul>
-	<li>For example, <code>101</code> and <code>12321</code> are palindromes.</li>
-</ul>
-
-<p>The test cases are generated so that the answer always exists and is in the range <code>[2, 2 * 10<sup>8</sup>]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 6
-<strong>Output:</strong> 7
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 8
-<strong>Output:</strong> 11
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> n = 13
-<strong>Output:</strong> 101
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/prime-palindrome/prime_palindrome.go b/problems/prime-palindrome/prime_palindrome.go
deleted file mode 100644
index 06e5ecec7..000000000
--- a/problems/prime-palindrome/prime_palindrome.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem866
diff --git a/problems/prime-palindrome/prime_palindrome_test.go b/problems/prime-palindrome/prime_palindrome_test.go
deleted file mode 100644
index 06e5ecec7..000000000
--- a/problems/prime-palindrome/prime_palindrome_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem866
diff --git a/problems/print-binary-tree/README.md b/problems/print-binary-tree/README.md
deleted file mode 100644
index 1cc4050d4..000000000
--- a/problems/print-binary-tree/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-binary-tree "Maximum Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../coin-path "Coin Path")
-
-## [655. Print Binary Tree (Medium)](https://leetcode.com/problems/print-binary-tree "输出二叉树")
-
-<p>Given the <code>root</code> of a binary tree, construct a <strong>0-indexed</strong> <code>m x n</code> string matrix <code>res</code> that represents a <strong>formatted layout</strong> of the tree. The formatted layout matrix should be constructed using the following rules:</p>
-
-<ul>
-	<li>The <strong>height</strong> of the tree is <code>height</code>&nbsp;and the number of rows <code>m</code> should be equal to <code>height + 1</code>.</li>
-	<li>The number of columns <code>n</code> should be equal to <code>2<sup>height+1</sup> - 1</code>.</li>
-	<li>Place the <strong>root node</strong> in the <strong>middle</strong> of the <strong>top row</strong> (more formally, at location <code>res[0][(n-1)/2]</code>).</li>
-	<li>For each node that has been placed in the matrix at position <code>res[r][c]</code>, place its <strong>left child</strong> at <code>res[r+1][c-2<sup>height-r-1</sup>]</code> and its <strong>right child</strong> at <code>res[r+1][c+2<sup>height-r-1</sup>]</code>.</li>
-	<li>Continue this process until all the nodes in the tree have been placed.</li>
-	<li>Any empty cells should contain the empty string <code>&quot;&quot;</code>.</li>
-</ul>
-
-<p>Return <em>the constructed matrix </em><code>res</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/print1-tree.jpg" style="width: 141px; height: 181px;" />
-<pre>
-<strong>Input:</strong> root = [1,2]
-<strong>Output:</strong> 
-[[&quot;&quot;,&quot;1&quot;,&quot;&quot;],
-&nbsp;[&quot;2&quot;,&quot;&quot;,&quot;&quot;]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/03/print2-tree.jpg" style="width: 207px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,null,4]
-<strong>Output:</strong> 
-[[&quot;&quot;,&quot;&quot;,&quot;&quot;,&quot;1&quot;,&quot;&quot;,&quot;&quot;,&quot;&quot;],
-&nbsp;[&quot;&quot;,&quot;2&quot;,&quot;&quot;,&quot;&quot;,&quot;&quot;,&quot;3&quot;,&quot;&quot;],
-&nbsp;[&quot;&quot;,&quot;&quot;,&quot;4&quot;,&quot;&quot;,&quot;&quot;,&quot;&quot;,&quot;&quot;]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 2<sup>10</sup>]</code>.</li>
-	<li><code>-99 &lt;= Node.val &lt;= 99</code></li>
-	<li>The depth of the tree will be in the range <code>[1, 10]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/print-binary-tree/print_binary_tree.go b/problems/print-binary-tree/print_binary_tree.go
deleted file mode 100644
index f2f85864b..000000000
--- a/problems/print-binary-tree/print_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem655
diff --git a/problems/print-binary-tree/print_binary_tree_test.go b/problems/print-binary-tree/print_binary_tree_test.go
deleted file mode 100644
index f2f85864b..000000000
--- a/problems/print-binary-tree/print_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem655
diff --git a/problems/print-foobar-alternately/README.md b/problems/print-foobar-alternately/README.md
deleted file mode 100644
index f059e20d7..000000000
--- a/problems/print-foobar-alternately/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../print-in-order "Print in Order")
-　　　　　　　　　　　　　　　　
-[Next >](../print-zero-even-odd "Print Zero Even Odd")
-
-## [1115. Print FooBar Alternately (Medium)](https://leetcode.com/problems/print-foobar-alternately "交替打印FooBar")
-
-<p>Suppose you are given the following code:</p>
-
-<pre>
-class FooBar {
-  public void foo() {
-    for (int i = 0; i &lt; n; i++) {
-      print(&quot;foo&quot;);
-    }
-  }
-
-  public void bar() {
-    for (int i = 0; i &lt; n; i++) {
-      print(&quot;bar&quot;);
-    }
-  }
-}
-</pre>
-
-<p>The same instance of <code>FooBar</code> will be passed to two different threads:</p>
-
-<ul>
-	<li>thread <code>A</code> will call <code>foo()</code>, while</li>
-	<li>thread <code>B</code> will call <code>bar()</code>.</li>
-</ul>
-
-<p>Modify the given program to output <code>&quot;foobar&quot;</code> <code>n</code> times.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> &quot;foobar&quot;
-<strong>Explanation:</strong> There are two threads being fired asynchronously. One of them calls foo(), while the other calls bar().
-&quot;foobar&quot; is being output 1 time.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> &quot;foobarfoobar&quot;
-<strong>Explanation:</strong> &quot;foobar&quot; is being output 2 times.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Concurrency](../../tag/concurrency/README.md)]
-
-### Similar Questions
-  1. [Print in Order](../print-in-order) (Easy)
-  1. [Print Zero Even Odd](../print-zero-even-odd) (Medium)
diff --git a/problems/print-foobar-alternately/print_foobar_alternately.py b/problems/print-foobar-alternately/print_foobar_alternately.py
deleted file mode 100755
index 5b00970e5..000000000
--- a/problems/print-foobar-alternately/print_foobar_alternately.py
+++ /dev/null
@@ -1,21 +0,0 @@
-#!/usr/bin/env python
-
-class FooBar:
-    def __init__(self, n):
-        self.n = n
-
-
-    def foo(self, printFoo: 'Callable[[], None]') -> None:
-        
-        for i in range(self.n):
-            
-            # printFoo() outputs "foo". Do not change or remove this line.
-        	printFoo()
-
-
-    def bar(self, printBar: 'Callable[[], None]') -> None:
-        
-        for i in range(self.n):
-            
-            # printBar() outputs "bar". Do not change or remove this line.
-        	printBar()
\ No newline at end of file
diff --git a/problems/print-immutable-linked-list-in-reverse/README.md b/problems/print-immutable-linked-list-in-reverse/README.md
deleted file mode 100644
index 28cd9038f..000000000
--- a/problems/print-immutable-linked-list-in-reverse/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../page-recommendations "Page Recommendations")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-time-visiting-all-points "Minimum Time Visiting All Points")
-
-## [1265. Print Immutable Linked List in Reverse (Medium)](https://leetcode.com/problems/print-immutable-linked-list-in-reverse "逆序打印不可变链表")
-
-You are given an immutable linked list, print out all values of each node in reverse with the help of the following interface:
-
-- ImmutableListNode: An interface of immutable linked list, you are given the head of the list.
-You need to use the following functions to access the linked list (you can't access the ImmutableListNode directly):
-
-- ImmutableListNode.printValue(): Print value of the current node.
-- ImmutableListNode.getNext(): Return the next node.
-The input is only given to initialize the linked list internally. You must solve this problem without modifying the linked list. In other words, you must operate the linked list using only the mentioned APIs.
-
-Follow up:
-
-Could you solve this problem in:
-
-- Constant space complexity?
-- Linear time complexity and less than linear space complexity?
- 
-<p><b>Example 1:</b></p>
-<pre>
-Input: head = [1,2,3,4]
-Output: [4,3,2,1]
-</pre>
-
-<p><b>Example 2:</b></p>
-<pre>
-Input: head = [0,-4,-1,3,-5]
-Output: [-5,3,-1,-4,0]
-</pre>
-
-<p><b>Example 3:</b></p>
-<pre>
-Input: head = [-2,0,6,4,4,-6]
-Output: [-6,4,4,6,0,-2]
-</pre>
- 
-Constraints:
-
-- The length of the linked list is between [1, 1000].
-- The value of each node in the linked list is between [-1000, 1000].
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
diff --git a/problems/print-in-order/README.md b/problems/print-in-order/README.md
deleted file mode 100644
index 2f0675943..000000000
--- a/problems/print-in-order/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reported-posts "Reported Posts")
-　　　　　　　　　　　　　　　　
-[Next >](../print-foobar-alternately "Print FooBar Alternately")
-
-## [1114. Print in Order (Easy)](https://leetcode.com/problems/print-in-order "按序打印")
-
-<p>Suppose we have a class:</p>
-
-<pre>
-public class Foo {
-  public void first() { print(&quot;first&quot;); }
-  public void second() { print(&quot;second&quot;); }
-  public void third() { print(&quot;third&quot;); }
-}
-</pre>
-
-<p>The same instance of <code>Foo</code> will be passed to three different threads. Thread A will call <code>first()</code>, thread B will call <code>second()</code>, and thread C will call <code>third()</code>. Design a mechanism and modify the program to ensure that <code>second()</code> is executed after <code>first()</code>, and <code>third()</code> is executed after <code>second()</code>.</p>
-
-<p><strong>Note:</strong></p>
-
-<p>We do not know how the threads will be scheduled in the operating system, even though the numbers in the input seem to imply the ordering. The input format you see is mainly to ensure our tests&#39; comprehensiveness.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> &quot;firstsecondthird&quot;
-<strong>Explanation:</strong> There are three threads being fired asynchronously. The input [1,2,3] means thread A calls first(), thread B calls second(), and thread C calls third(). &quot;firstsecondthird&quot; is the correct output.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,2]
-<strong>Output:</strong> &quot;firstsecondthird&quot;
-<strong>Explanation:</strong> The input [1,3,2] means thread A calls first(), thread B calls third(), and thread C calls second(). &quot;firstsecondthird&quot; is the correct output.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>nums</code> is a permutation of <code>[1, 2, 3]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Concurrency](../../tag/concurrency/README.md)]
-
-### Similar Questions
-  1. [Print FooBar Alternately](../print-foobar-alternately) (Medium)
diff --git a/problems/print-in-order/print_in_order.py b/problems/print-in-order/print_in_order.py
deleted file mode 100755
index 8cabb5e08..000000000
--- a/problems/print-in-order/print_in_order.py
+++ /dev/null
@@ -1,23 +0,0 @@
-#!/usr/bin/env python
-
-class Foo:
-    def __init__(self):
-        pass
-
-
-    def first(self, printFirst: 'Callable[[], None]') -> None:
-        
-        # printFirst() outputs "first". Do not change or remove this line.
-        printFirst()
-
-
-    def second(self, printSecond: 'Callable[[], None]') -> None:
-        
-        # printSecond() outputs "second". Do not change or remove this line.
-        printSecond()
-
-
-    def third(self, printThird: 'Callable[[], None]') -> None:
-        
-        # printThird() outputs "third". Do not change or remove this line.
-        printThird()
\ No newline at end of file
diff --git a/problems/print-words-vertically/README.md b/problems/print-words-vertically/README.md
deleted file mode 100644
index 76e308fc7..000000000
--- a/problems/print-words-vertically/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-69-number "Maximum 69 Number")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-leaves-with-a-given-value "Delete Leaves With a Given Value")
-
-## [1324. Print Words Vertically (Medium)](https://leetcode.com/problems/print-words-vertically "竖直打印单词")
-
-<p>Given a string <code>s</code>.&nbsp;Return&nbsp;all the words vertically in the same order in which they appear in <code>s</code>.<br />
-Words are returned as a list of strings, complete with&nbsp;spaces when is necessary. (Trailing spaces are not allowed).<br />
-Each word would be put on only one column and that in one column there will be only one word.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;HOW ARE YOU&quot;
-<strong>Output:</strong> [&quot;HAY&quot;,&quot;ORO&quot;,&quot;WEU&quot;]
-<strong>Explanation: </strong>Each word is printed vertically. 
- &quot;HAY&quot;
-&nbsp;&quot;ORO&quot;
-&nbsp;&quot;WEU&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;TO BE OR NOT TO BE&quot;
-<strong>Output:</strong> [&quot;TBONTB&quot;,&quot;OEROOE&quot;,&quot;   T&quot;]
-<strong>Explanation: </strong>Trailing spaces is not allowed. 
-&quot;TBONTB&quot;
-&quot;OEROOE&quot;
-&quot;   T&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;CONTEST IS COMING&quot;
-<strong>Output:</strong> [&quot;CIC&quot;,&quot;OSO&quot;,&quot;N M&quot;,&quot;T I&quot;,&quot;E N&quot;,&quot;S G&quot;,&quot;T&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 200</code></li>
-	<li><code>s</code>&nbsp;contains only upper case English letters.</li>
-	<li>It&#39;s guaranteed that there is only one&nbsp;space between 2 words.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use the maximum length of words to determine the length of the returned answer. However, don't forget to remove trailing spaces.
-</details>
diff --git a/problems/print-zero-even-odd/README.md b/problems/print-zero-even-odd/README.md
deleted file mode 100644
index e053c905b..000000000
--- a/problems/print-zero-even-odd/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../print-foobar-alternately "Print FooBar Alternately")
-　　　　　　　　　　　　　　　　
-[Next >](../building-h2o "Building H2O")
-
-## [1116. Print Zero Even Odd (Medium)](https://leetcode.com/problems/print-zero-even-odd "打印零与奇偶数")
-
-<p>You have a function <code>printNumber</code> that can be called with an integer parameter and prints it to the console.</p>
-
-<ul>
-	<li>For example, calling <code>printNumber(7)</code> prints <code>7</code> to the console.</li>
-</ul>
-
-<p>You are given an instance of the class <code>ZeroEvenOdd</code> that has three functions: <code>zero</code>, <code>even</code>, and <code>odd</code>. The same instance of <code>ZeroEvenOdd</code> will be passed to three different threads:</p>
-
-<ul>
-	<li><strong>Thread A:</strong> calls <code>zero()</code> that should only output <code>0</code>&#39;s.</li>
-	<li><strong>Thread B:</strong> calls <code>even()</code> that should only output even numbers.</li>
-	<li><strong>Thread C:</strong> calls <code>odd()</code> that should only output odd numbers.</li>
-</ul>
-
-<p>Modify the given class to output the series <code>&quot;010203040506...&quot;</code> where the length of the series must be <code>2n</code>.</p>
-
-<p>Implement the <code>ZeroEvenOdd</code> class:</p>
-
-<ul>
-	<li><code>ZeroEvenOdd(int n)</code> Initializes the object with the number <code>n</code> that represents the numbers that should be printed.</li>
-	<li><code>void zero(printNumber)</code> Calls <code>printNumber</code> to output one zero.</li>
-	<li><code>void even(printNumber)</code> Calls <code>printNumber</code> to output one even number.</li>
-	<li><code>void odd(printNumber)</code> Calls <code>printNumber</code> to output one odd number.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> &quot;0102&quot;
-<strong>Explanation:</strong> There are three threads being fired asynchronously.
-One of them calls zero(), the other calls even(), and the last one calls odd().
-&quot;0102&quot; is the correct output.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5
-<strong>Output:</strong> &quot;0102030405&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Concurrency](../../tag/concurrency/README.md)]
-
-### Similar Questions
-  1. [Print FooBar Alternately](../print-foobar-alternately) (Medium)
diff --git a/problems/print-zero-even-odd/print_zero_even_odd.py b/problems/print-zero-even-odd/print_zero_even_odd.py
deleted file mode 100755
index a9951a670..000000000
--- a/problems/print-zero-even-odd/print_zero_even_odd.py
+++ /dev/null
@@ -1,17 +0,0 @@
-#!/usr/bin/env python
-
-class ZeroEvenOdd:
-    def __init__(self, n):
-        self.n = n
-        
-        
-	# printNumber(x) outputs "x", where x is an integer.
-    def zero(self, printNumber: 'Callable[[int], None]') -> None:
-        
-        
-        
-    def even(self, printNumber: 'Callable[[int], None]') -> None:
-        
-        
-        
-    def odd(self, printNumber: 'Callable[[int], None]') -> None:
\ No newline at end of file
diff --git a/problems/prison-cells-after-n-days/README.md b/problems/prison-cells-after-n-days/README.md
deleted file mode 100644
index 1459ec6aa..000000000
--- a/problems/prison-cells-after-n-days/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../tallest-billboard "Tallest Billboard")
-　　　　　　　　　　　　　　　　
-[Next >](../check-completeness-of-a-binary-tree "Check Completeness of a Binary Tree")
-
-## [957. Prison Cells After N Days (Medium)](https://leetcode.com/problems/prison-cells-after-n-days "N 天后的牢房")
-
-<p>There are <code>8</code> prison cells in a row and each cell is either occupied or vacant.</p>
-
-<p>Each day, whether the cell is occupied or vacant changes according to the following rules:</p>
-
-<ul>
-	<li>If a cell has two adjacent neighbors that are both occupied or both vacant, then the cell becomes occupied.</li>
-	<li>Otherwise, it becomes vacant.</li>
-</ul>
-
-<p><strong>Note</strong> that because the prison is a row, the first and the last cells in the row can&#39;t have two adjacent neighbors.</p>
-
-<p>You are given an integer array <code>cells</code> where <code>cells[i] == 1</code> if the <code>i<sup>th</sup></code> cell is occupied and <code>cells[i] == 0</code> if the <code>i<sup>th</sup></code> cell is vacant, and you are given an integer <code>n</code>.</p>
-
-<p>Return the state of the prison after <code>n</code> days (i.e., <code>n</code> such changes described above).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> cells = [0,1,0,1,1,0,0,1], n = 7
-<strong>Output:</strong> [0,0,1,1,0,0,0,0]
-<strong>Explanation:</strong> The following table summarizes the state of the prison on each day:
-Day 0: [0, 1, 0, 1, 1, 0, 0, 1]
-Day 1: [0, 1, 1, 0, 0, 0, 0, 0]
-Day 2: [0, 0, 0, 0, 1, 1, 1, 0]
-Day 3: [0, 1, 1, 0, 0, 1, 0, 0]
-Day 4: [0, 0, 0, 0, 0, 1, 0, 0]
-Day 5: [0, 1, 1, 1, 0, 1, 0, 0]
-Day 6: [0, 0, 1, 0, 1, 1, 0, 0]
-Day 7: [0, 0, 1, 1, 0, 0, 0, 0]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> cells = [1,0,0,1,0,0,1,0], n = 1000000000
-<strong>Output:</strong> [0,0,1,1,1,1,1,0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>cells.length == 8</code></li>
-	<li><code>cells[i]</code>&nbsp;is either <code>0</code> or <code>1</code>.</li>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
diff --git a/problems/prison-cells-after-n-days/prison_cells_after_n_days.go b/problems/prison-cells-after-n-days/prison_cells_after_n_days.go
deleted file mode 100644
index 9b15fd97d..000000000
--- a/problems/prison-cells-after-n-days/prison_cells_after_n_days.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem957
diff --git a/problems/prison-cells-after-n-days/prison_cells_after_n_days_test.go b/problems/prison-cells-after-n-days/prison_cells_after_n_days_test.go
deleted file mode 100644
index 9b15fd97d..000000000
--- a/problems/prison-cells-after-n-days/prison_cells_after_n_days_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem957
diff --git a/problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls/README.md b/problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls/README.md
deleted file mode 100644
index 4e558e1e6..000000000
--- a/problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reorder-routes-to-make-all-paths-lead-to-the-city-zero "Reorder Routes to Make All Paths Lead to the City Zero")
-　　　　　　　　　　　　　　　　
-[Next >](../calculate-salaries "Calculate Salaries")
-
-## [1467. Probability of a Two Boxes Having The Same Number of Distinct Balls (Hard)](https://leetcode.com/problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls "两个盒子中球的颜色数相同的概率")
-
-<p>Given <code>2n</code> balls of <code>k</code> distinct colors. You will be given an integer array <code>balls</code> of size <code>k</code> where <code>balls[i]</code> is the number of balls of color <code>i</code>.</p>
-
-<p>All the balls will be <strong>shuffled uniformly at random</strong>, then we will distribute the first <code>n</code> balls to the first box and the remaining <code>n</code> balls to the other box (Please read the explanation of the second example carefully).</p>
-
-<p>Please note that the two boxes are considered different. For example, if we have two balls of colors <code>a</code> and <code>b</code>, and two boxes <code>[]</code> and <code>()</code>, then the distribution <code>[a] (b)</code> is considered different than the distribution <code>[b] (a) </code>(Please read the explanation of the first example carefully).</p>
-
-<p>Return<em> the probability</em> that the two boxes have the same number of distinct balls. Answers within <code>10<sup>-5</sup></code> of the actual value will be accepted as correct.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> balls = [1,1]
-<strong>Output:</strong> 1.00000
-<strong>Explanation:</strong> Only 2 ways to divide the balls equally:
-- A ball of color 1 to box 1 and a ball of color 2 to box 2
-- A ball of color 2 to box 1 and a ball of color 1 to box 2
-In both ways, the number of distinct colors in each box is equal. The probability is 2/2 = 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> balls = [2,1,1]
-<strong>Output:</strong> 0.66667
-<strong>Explanation:</strong> We have the set of balls [1, 1, 2, 3]
-This set of balls will be shuffled randomly and we may have one of the 12 distinct shuffles with equal probability (i.e. 1/12):
-[1,1 / 2,3], [1,1 / 3,2], [1,2 / 1,3], [1,2 / 3,1], [1,3 / 1,2], [1,3 / 2,1], [2,1 / 1,3], [2,1 / 3,1], [2,3 / 1,1], [3,1 / 1,2], [3,1 / 2,1], [3,2 / 1,1]
-After that, we add the first two balls to the first box and the second two balls to the second box.
-We can see that 8 of these 12 possible random distributions have the same number of distinct colors of balls in each box.
-Probability is 8/12 = 0.66667
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> balls = [1,2,1,2]
-<strong>Output:</strong> 0.60000
-<strong>Explanation:</strong> The set of balls is [1, 2, 2, 3, 4, 4]. It is hard to display all the 180 possible random shuffles of this set but it is easy to check that 108 of them will have the same number of distinct colors in each box.
-Probability = 108 / 180 = 0.6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= balls.length &lt;= 8</code></li>
-	<li><code>1 &lt;= balls[i] &lt;= 6</code></li>
-	<li><code>sum(balls)</code> is even.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-  [[Probability and Statistics](../../tag/probability-and-statistics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check how many ways you can distribute the balls between the boxes.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Consider that one way you will use (x1, x2, x3, ..., xk) where xi is the number of balls from colour i. The probability of achieving this way randomly is ( (ball1 C x1) * (ball2 C x2) * (ball3 C x3) * ... * (ballk C xk)) / (2n C n).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The probability of a draw is the sigma of probabilities of different ways to achieve draw.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Can you use Dynamic programming to solve this problem in a better complexity ?
-</details>
diff --git a/problems/process-restricted-friend-requests/README.md b/problems/process-restricted-friend-requests/README.md
deleted file mode 100644
index cd6c67d9f..000000000
--- a/problems/process-restricted-friend-requests/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decode-the-slanted-ciphertext "Decode the Slanted Ciphertext")
-　　　　　　　　　　　　　　　　
-[Next >](../paths-in-maze-that-lead-to-same-room "Paths in Maze That Lead to Same Room")
-
-## [2076. Process Restricted Friend Requests (Hard)](https://leetcode.com/problems/process-restricted-friend-requests "处理含限制条件的好友请求")
-
-<p>You are given an integer <code>n</code> indicating the number of people in a network. Each person is labeled from <code>0</code> to <code>n - 1</code>.</p>
-
-<p>You are also given a <strong>0-indexed</strong> 2D integer array <code>restrictions</code>, where <code>restrictions[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> means that person <code>x<sub>i</sub></code> and person <code>y<sub>i</sub></code> <strong>cannot </strong>become <strong>friends</strong>,<strong> </strong>either <strong>directly</strong> or <strong>indirectly</strong> through other people.</p>
-
-<p>Initially, no one is friends with each other. You are given a list of friend requests as a <strong>0-indexed</strong> 2D integer array <code>requests</code>, where <code>requests[j] = [u<sub>j</sub>, v<sub>j</sub>]</code> is a friend request between person <code>u<sub>j</sub></code> and person <code>v<sub>j</sub></code>.</p>
-
-<p>A friend request is <strong>successful </strong>if <code>u<sub>j</sub></code> and <code>v<sub>j</sub></code> can be <strong>friends</strong>. Each friend request is processed in the given order (i.e., <code>requests[j]</code> occurs before <code>requests[j + 1]</code>), and upon a successful request, <code>u<sub>j</sub></code> and <code>v<sub>j</sub></code> <strong>become direct friends</strong> for all future friend requests.</p>
-
-<p>Return <em>a <strong>boolean array</strong> </em><code>result</code>,<em> where each </em><code>result[j]</code><em> is </em><code>true</code><em> if the </em><code>j<sup>th</sup></code><em> friend request is <strong>successful</strong> or </em><code>false</code><em> if it is not</em>.</p>
-
-<p><strong>Note:</strong> If <code>u<sub>j</sub></code> and <code>v<sub>j</sub></code> are already direct friends, the request is still <strong>successful</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, restrictions = [[0,1]], requests = [[0,2],[2,1]]
-<strong>Output:</strong> [true,false]
-<strong>Explanation:
-</strong>Request 0: Person 0 and person 2 can be friends, so they become direct friends. 
-Request 1: Person 2 and person 1 cannot be friends since person 0 and person 1 would be indirect friends (1--2--0).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, restrictions = [[0,1]], requests = [[1,2],[0,2]]
-<strong>Output:</strong> [true,false]
-<strong>Explanation:
-</strong>Request 0: Person 1 and person 2 can be friends, so they become direct friends.
-Request 1: Person 0 and person 2 cannot be friends since person 0 and person 1 would be indirect friends (0--2--1).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, restrictions = [[0,1],[1,2],[2,3]], requests = [[0,4],[1,2],[3,1],[3,4]]
-<strong>Output:</strong> [true,false,true,false]
-<strong>Explanation:
-</strong>Request 0: Person 0 and person 4 can be friends, so they become direct friends.
-Request 1: Person 1 and person 2 cannot be friends since they are directly restricted.
-Request 2: Person 3 and person 1 can be friends, so they become direct friends.
-Request 3: Person 3 and person 4 cannot be friends since person 0 and person 1 would be indirect friends (0--4--3--1).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 1000</code></li>
-	<li><code>0 &lt;= restrictions.length &lt;= 1000</code></li>
-	<li><code>restrictions[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>x<sub>i</sub> != y<sub>i</sub></code></li>
-	<li><code>1 &lt;= requests.length &lt;= 1000</code></li>
-	<li><code>requests[j].length == 2</code></li>
-	<li><code>0 &lt;= u<sub>j</sub>, v<sub>j</sub> &lt;= n - 1</code></li>
-	<li><code>u<sub>j</sub> != v<sub>j</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each request, we could loop through all restrictions. Can you think of doing a check-in close to O(1)?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Could you use Union Find?
-</details>
diff --git a/problems/process-tasks-using-servers/README.md b/problems/process-tasks-using-servers/README.md
deleted file mode 100644
index d2523efe7..000000000
--- a/problems/process-tasks-using-servers/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-value-after-insertion "Maximum Value after Insertion")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-skips-to-arrive-at-meeting-on-time "Minimum Skips to Arrive at Meeting On Time")
-
-## [1882. Process Tasks Using Servers (Medium)](https://leetcode.com/problems/process-tasks-using-servers "使用服务器处理任务")
-
-<p>You are given two <strong>0-indexed</strong> integer arrays <code>servers</code> and <code>tasks</code> of lengths <code>n</code>​​​​​​ and <code>m</code>​​​​​​ respectively. <code>servers[i]</code> is the <strong>weight</strong> of the <code>i<sup>​​​​​​th</sup></code>​​​​ server, and <code>tasks[j]</code> is the <strong>time needed</strong> to process the <code>j<sup>​​​​​​th</sup></code>​​​​ task <strong>in seconds</strong>.</p>
-
-<p>Tasks are assigned to the servers using a <strong>task queue</strong>. Initially, all servers are free, and the queue is <strong>empty</strong>.</p>
-
-<p>At second <code>j</code>, the <code>j<sup>th</sup></code> task is <strong>inserted</strong> into the queue (starting with the <code>0<sup>th</sup></code> task being inserted at second <code>0</code>). As long as there are free servers and the queue is not empty, the task in the front of the queue will be assigned to a free server with the <strong>smallest weight</strong>, and in case of a tie, it is assigned to a free server with the <strong>smallest index</strong>.</p>
-
-<p>If there are no free servers and the queue is not empty, we wait until a server becomes free and immediately assign the next task. If multiple servers become free at the same time, then multiple tasks from the queue will be assigned <strong>in order of insertion</strong> following the weight and index priorities above.</p>
-
-<p>A server that is assigned task <code>j</code> at second <code>t</code> will be free again at second <code>t + tasks[j]</code>.</p>
-
-<p>Build an array <code>ans</code>​​​​ of length <code>m</code>, where <code>ans[j]</code> is the <strong>index</strong> of the server the <code>j<sup>​​​​​​th</sup></code> task will be assigned to.</p>
-
-<p>Return <em>the array </em><code>ans</code>​​​​.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> servers = [3,3,2], tasks = [1,2,3,2,1,2]
-<strong>Output:</strong> [2,2,0,2,1,2]
-<strong>Explanation: </strong>Events in chronological order go as follows:
-- At second 0, task 0 is added and processed using server 2 until second 1.
-- At second 1, server 2 becomes free. Task 1 is added and processed using server 2 until second 3.
-- At second 2, task 2 is added and processed using server 0 until second 5.
-- At second 3, server 2 becomes free. Task 3 is added and processed using server 2 until second 5.
-- At second 4, task 4 is added and processed using server 1 until second 5.
-- At second 5, all servers become free. Task 5 is added and processed using server 2 until second 7.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> servers = [5,1,4,3,2], tasks = [2,1,2,4,5,2,1]
-<strong>Output:</strong> [1,4,1,4,1,3,2]
-<strong>Explanation: </strong>Events in chronological order go as follows: 
-- At second 0, task 0 is added and processed using server 1 until second 2.
-- At second 1, task 1 is added and processed using server 4 until second 2.
-- At second 2, servers 1 and 4 become free. Task 2 is added and processed using server 1 until second 4. 
-- At second 3, task 3 is added and processed using server 4 until second 7.
-- At second 4, server 1 becomes free. Task 4 is added and processed using server 1 until second 9. 
-- At second 5, task 5 is added and processed using server 3 until second 7.
-- At second 6, task 6 is added and processed using server 2 until second 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>servers.length == n</code></li>
-	<li><code>tasks.length == m</code></li>
-	<li><code>1 &lt;= n, m &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= servers[i], tasks[j] &lt;= 2 * 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can maintain a Heap of available Servers and a Heap of unavailable servers
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Note that the tasks will be processed in the input order so you just need to find the x-th server that will be available according to the rules
-</details>
diff --git a/problems/product-of-array-except-self/README.md b/problems/product-of-array-except-self/README.md
deleted file mode 100644
index 0b3fe0d47..000000000
--- a/problems/product-of-array-except-self/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-node-in-a-linked-list "Delete Node in a Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../sliding-window-maximum "Sliding Window Maximum")
-
-## [238. Product of Array Except Self (Medium)](https://leetcode.com/problems/product-of-array-except-self "除自身以外数组的乘积")
-
-<p>Given an integer array <code>nums</code>, return <em>an array</em> <code>answer</code> <em>such that</em> <code>answer[i]</code> <em>is equal to the product of all the elements of</em> <code>nums</code> <em>except</em> <code>nums[i]</code>.</p>
-
-<p>The product of any prefix or suffix of <code>nums</code> is <strong>guaranteed</strong> to fit in a <strong>32-bit</strong> integer.</p>
-
-<p>You must write an algorithm that runs in&nbsp;<code>O(n)</code>&nbsp;time and without using the division operation.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> [24,12,8,6]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [-1,1,0,-3,3]
-<strong>Output:</strong> [0,0,9,0,0]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-30 &lt;= nums[i] &lt;= 30</code></li>
-	<li>The product of any prefix or suffix of <code>nums</code> is <strong>guaranteed</strong> to fit in a <strong>32-bit</strong> integer.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong>&nbsp;Can you solve the problem in <code>O(1)&nbsp;</code>extra&nbsp;space complexity? (The output array <strong>does not</strong> count as extra space for space complexity analysis.)</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Trapping Rain Water](../trapping-rain-water) (Hard)
-  1. [Maximum Product Subarray](../maximum-product-subarray) (Medium)
-  1. [Paint House II](../paint-house-ii) (Hard)
diff --git a/problems/product-of-array-except-self/product_of_array_except_self.go b/problems/product-of-array-except-self/product_of_array_except_self.go
deleted file mode 100644
index d62cce022..000000000
--- a/problems/product-of-array-except-self/product_of_array_except_self.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem238
diff --git a/problems/product-of-array-except-self/product_of_array_except_self_test.go b/problems/product-of-array-except-self/product_of_array_except_self_test.go
deleted file mode 100644
index d62cce022..000000000
--- a/problems/product-of-array-except-self/product_of_array_except_self_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem238
diff --git a/problems/product-of-the-last-k-numbers/README.md b/problems/product-of-the-last-k-numbers/README.md
deleted file mode 100644
index f09bf9ba2..000000000
--- a/problems/product-of-the-last-k-numbers/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-negative-numbers-in-a-sorted-matrix "Count Negative Numbers in a Sorted Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-events-that-can-be-attended "Maximum Number of Events That Can Be Attended")
-
-## [1352. Product of the Last K Numbers (Medium)](https://leetcode.com/problems/product-of-the-last-k-numbers "最后 K 个数的乘积")
-
-<p>Design an algorithm that accepts a stream of integers and retrieves the product of the last <code>k</code> integers of the stream.</p>
-
-<p>Implement the <code>ProductOfNumbers</code> class:</p>
-
-<ul>
-	<li><code>ProductOfNumbers()</code> Initializes the object with an empty stream.</li>
-	<li><code>void add(int num)</code> Appends the integer <code>num</code> to the stream.</li>
-	<li><code>int getProduct(int k)</code> Returns the product of the last <code>k</code> numbers in the current list. You can assume that always the current list has at least <code>k</code> numbers.</li>
-</ul>
-
-<p>The test cases are generated so that, at any time, the product of any contiguous sequence of numbers will fit into a single 32-bit integer without overflowing.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;ProductOfNumbers&quot;,&quot;add&quot;,&quot;add&quot;,&quot;add&quot;,&quot;add&quot;,&quot;add&quot;,&quot;getProduct&quot;,&quot;getProduct&quot;,&quot;getProduct&quot;,&quot;add&quot;,&quot;getProduct&quot;]
-[[],[3],[0],[2],[5],[4],[2],[3],[4],[8],[2]]
-
-<strong>Output</strong>
-[null,null,null,null,null,null,20,40,0,null,32]
-
-<strong>Explanation</strong>
-ProductOfNumbers productOfNumbers = new ProductOfNumbers();
-productOfNumbers.add(3);        // [3]
-productOfNumbers.add(0);        // [3,0]
-productOfNumbers.add(2);        // [3,0,2]
-productOfNumbers.add(5);        // [3,0,2,5]
-productOfNumbers.add(4);        // [3,0,2,5,4]
-productOfNumbers.getProduct(2); // return 20. The product of the last 2 numbers is 5 * 4 = 20
-productOfNumbers.getProduct(3); // return 40. The product of the last 3 numbers is 2 * 5 * 4 = 40
-productOfNumbers.getProduct(4); // return 0. The product of the last 4 numbers is 0 * 2 * 5 * 4 = 0
-productOfNumbers.add(8);        // [3,0,2,5,4,8]
-productOfNumbers.getProduct(2); // return 32. The product of the last 2 numbers is 4 * 8 = 32 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= num &lt;= 100</code></li>
-	<li><code>1 &lt;= k &lt;= 4 * 10<sup>4</sup></code></li>
-	<li>At most <code>4 * 10<sup>4</sup></code> calls will be made to <code>add</code> and <code>getProduct</code>.</li>
-	<li>The product of the stream at any point in time will fit in a <strong>32-bit</strong> integer.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep all prefix products of numbers in an array, then calculate the product of last K elements in O(1) complexity.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-When a zero number is added, clean the array of prefix products.
-</details>
diff --git a/problems/product-of-two-run-length-encoded-arrays/README.md b/problems/product-of-two-run-length-encoded-arrays/README.md
deleted file mode 100644
index 60b12f2ad..000000000
--- a/problems/product-of-two-run-length-encoded-arrays/README.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../orders-with-maximum-quantity-above-average "Orders With Maximum Quantity Above Average")
-　　　　　　　　　　　　　　　　
-[Next >](../longer-contiguous-segments-of-ones-than-zeros "Longer Contiguous Segments of Ones than Zeros")
-
-## [1868. Product of Two Run-Length Encoded Arrays (Medium)](https://leetcode.com/problems/product-of-two-run-length-encoded-arrays "两个行程编码数组的积")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep track of the indices on both RLE arrays and join the parts together.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What is the maximum number of segments if we took the minimum number of elements left on both the current segments every time?
-</details>
diff --git a/problems/product-price-at-a-given-date/README.md b/problems/product-price-at-a-given-date/README.md
deleted file mode 100644
index 3a1cd5645..000000000
--- a/problems/product-price-at-a-given-date/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../last-substring-in-lexicographical-order "Last Substring in Lexicographical Order")
-　　　　　　　　　　　　　　　　
-[Next >](../single-row-keyboard "Single-Row Keyboard")
-
-## [1164. Product Price at a Given Date (Medium)](https://leetcode.com/problems/product-price-at-a-given-date "指定日期的产品价格")
-
-<p>Table: <code>Products</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| product_id    | int     |
-| new_price     | int     |
-| change_date   | date    |
-+---------------+---------+
-(product_id, change_date) is the primary key of this table.
-Each row of this table indicates that the price of some product was changed to a new price at some date.</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find the prices of all products on <strong>2019-08-16</strong>. Assume the price of all products before any change is <strong>10</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-<code>Products</code> table:
-+------------+-----------+-------------+
-| product_id | new_price | change_date |
-+------------+-----------+-------------+
-| 1          | 20        | 2019-08-14  |
-| 2          | 50        | 2019-08-14  |
-| 1          | 30        | 2019-08-15  |
-| 1          | 35        | 2019-08-16  |
-| 2          | 65        | 2019-08-17  |
-| 3          | 20        | 2019-08-18  |
-+------------+-----------+-------------+
-
-Result table:
-+------------+-------+
-| product_id | price |
-+------------+-------+
-| 2          | 50    |
-| 1          | 35    |
-| 3          | 10    |
-+------------+-------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/product-price-at-a-given-date/mysql_schemas.sql b/problems/product-price-at-a-given-date/mysql_schemas.sql
deleted file mode 100644
index 65061d821..000000000
--- a/problems/product-price-at-a-given-date/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Products (product_id int, new_price int, change_date date);
-Truncate table Products;
-insert into Products (product_id, new_price, change_date) values ('1', '20', '2019-08-14');
-insert into Products (product_id, new_price, change_date) values ('2', '50', '2019-08-14');
-insert into Products (product_id, new_price, change_date) values ('1', '30', '2019-08-15');
-insert into Products (product_id, new_price, change_date) values ('1', '35', '2019-08-16');
-insert into Products (product_id, new_price, change_date) values ('2', '65', '2019-08-17');
-insert into Products (product_id, new_price, change_date) values ('3', '20', '2019-08-18');
diff --git a/problems/product-sales-analysis-i/README.md b/problems/product-sales-analysis-i/README.md
deleted file mode 100644
index e79cb23de..000000000
--- a/problems/product-sales-analysis-i/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../digit-count-in-range "Digit Count in Range")
-　　　　　　　　　　　　　　　　
-[Next >](../product-sales-analysis-ii "Product Sales Analysis II")
-
-## [1068. Product Sales Analysis I (Easy)](https://leetcode.com/problems/product-sales-analysis-i "产品销售分析 I")
-
-<p>Table:&nbsp;<code>Sales</code></p>
-
-<pre>
-+-------------+-------+
-| Column Name | Type  |
-+-------------+-------+
-| sale_id     | int   |
-| product_id  | int   |
-| year        | int   |
-| quantity    | int   |
-| price       | int   |
-+-------------+-------+
-(sale_id, year) is the primary key of this table.
-product_id is a foreign key to <code>Product</code> table.
-Note that the price is per unit.
-</pre>
-
-<p>Table:&nbsp;<code>Product</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| product_id   | int     |
-| product_name | varchar |
-+--------------+---------+
-product_id is the primary key of this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports all <strong>product names</strong> of the products in the <code>Sales</code> table along with their selling <strong>year</strong> and&nbsp;<strong>price</strong>.</p>
-
-<p>For example:</p>
-
-<pre>
-<code>Sales</code> table:
-+---------+------------+------+----------+-------+
-| sale_id | product_id | year | quantity | price |
-+---------+------------+------+----------+-------+ 
-| 1       | 100        | 2008 | 10       | 5000  |
-| 2       | 100        | 2009 | 12       | 5000  |
-| 7       | 200        | 2011 | 15       | 9000  |
-+---------+------------+------+----------+-------+
-
-Product table:
-+------------+--------------+
-| product_id | product_name |
-+------------+--------------+
-| 100        | Nokia        |
-| 200        | Apple        |
-| 300        | Samsung      |
-+------------+--------------+
-
-Result table:
-+--------------+-------+-------+
-| product_name | year  | price |
-+--------------+-------+-------+
-| Nokia        | 2008  | 5000  |
-| Nokia        | 2009  | 5000  |
-| Apple        | 2011  | 9000  |
-+--------------+-------+-------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/product-sales-analysis-i/mysql_schemas.sql b/problems/product-sales-analysis-i/mysql_schemas.sql
deleted file mode 100644
index 592f4f5a9..000000000
--- a/problems/product-sales-analysis-i/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table Sales (sale_id int, product_id int, year int, quantity int, price int);
-Create table Product (product_id int, product_name varchar(10));
-Truncate table Sales;
-insert into Sales (sale_id, product_id, year, quantity, price) values ('1', '100', '2008', '10', '5000');
-insert into Sales (sale_id, product_id, year, quantity, price) values ('2', '100', '2009', '12', '5000');
-insert into Sales (sale_id, product_id, year, quantity, price) values ('7', '200', '2011', '15', '9000');
-Truncate table Product;
-insert into Product (product_id, product_name) values ('100', 'Nokia');
-insert into Product (product_id, product_name) values ('200', 'Apple');
-insert into Product (product_id, product_name) values ('300', 'Samsung');
diff --git a/problems/product-sales-analysis-i/product_sales_analysis_i.sql b/problems/product-sales-analysis-i/product_sales_analysis_i.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/product-sales-analysis-i/product_sales_analysis_i.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/product-sales-analysis-ii/README.md b/problems/product-sales-analysis-ii/README.md
deleted file mode 100644
index 3e35e1e17..000000000
--- a/problems/product-sales-analysis-ii/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../product-sales-analysis-i "Product Sales Analysis I")
-　　　　　　　　　　　　　　　　
-[Next >](../product-sales-analysis-iii "Product Sales Analysis III")
-
-## [1069. Product Sales Analysis II (Easy)](https://leetcode.com/problems/product-sales-analysis-ii "产品销售分析 II")
-
-<p>Table:&nbsp;<code>Sales</code></p>
-
-<pre>
-+-------------+-------+
-| Column Name | Type  |
-+-------------+-------+
-| sale_id     | int   |
-| product_id  | int   |
-| year        | int   |
-| quantity    | int   |
-| price       | int   |
-+-------------+-------+
-sale_id is the primary key of this table.
-product_id is a foreign key to <code>Product</code> table.
-Note that the price is per unit.
-</pre>
-
-<p>Table:&nbsp;<code>Product</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| product_id   | int     |
-| product_name | varchar |
-+--------------+---------+
-product_id is the primary key of this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the total quantity sold for every product id.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-<code>Sales</code> table:
-+---------+------------+------+----------+-------+
-| sale_id | product_id | year | quantity | price |
-+---------+------------+------+----------+-------+ 
-| 1       | 100        | 2008 | 10       | 5000  |
-| 2       | 100        | 2009 | 12       | 5000  |
-| 7       | 200        | 2011 | 15       | 9000  |
-+---------+------------+------+----------+-------+
-
-Product table:
-+------------+--------------+
-| product_id | product_name |
-+------------+--------------+
-| 100        | Nokia        |
-| 200        | Apple        |
-| 300        | Samsung      |
-+------------+--------------+
-
-Result table:
-+--------------+----------------+
-| product_id   | total_quantity |
-+--------------+----------------+
-| 100          | 22             |
-| 200          | 15             |
-+--------------+----------------+</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Product Sales Analysis I](../product-sales-analysis-i) (Easy)
-  1. [Product Sales Analysis III](../product-sales-analysis-iii) (Medium)
diff --git a/problems/product-sales-analysis-ii/mysql_schemas.sql b/problems/product-sales-analysis-ii/mysql_schemas.sql
deleted file mode 100644
index 2d7632cb2..000000000
--- a/problems/product-sales-analysis-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Sales (sale_id int, product_id int, year int, quantity int, price int);
-Create table If Not Exists Product (product_id int, product_name varchar(10));
-Truncate table Sales;
-insert into Sales (sale_id, product_id, year, quantity, price) values ('1', '100', '2008', '10', '5000');
-insert into Sales (sale_id, product_id, year, quantity, price) values ('2', '100', '2009', '12', '5000');
-insert into Sales (sale_id, product_id, year, quantity, price) values ('7', '200', '2011', '15', '9000');
-Truncate table Product;
-insert into Product (product_id, product_name) values ('100', 'Nokia');
-insert into Product (product_id, product_name) values ('200', 'Apple');
-insert into Product (product_id, product_name) values ('300', 'Samsung');
diff --git a/problems/product-sales-analysis-ii/product_sales_analysis_ii.sql b/problems/product-sales-analysis-ii/product_sales_analysis_ii.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/product-sales-analysis-ii/product_sales_analysis_ii.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/product-sales-analysis-iii/README.md b/problems/product-sales-analysis-iii/README.md
deleted file mode 100644
index ceec81328..000000000
--- a/problems/product-sales-analysis-iii/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../product-sales-analysis-ii "Product Sales Analysis II")
-　　　　　　　　　　　　　　　　
-[Next >](../greatest-common-divisor-of-strings "Greatest Common Divisor of Strings")
-
-## [1070. Product Sales Analysis III (Medium)](https://leetcode.com/problems/product-sales-analysis-iii "产品销售分析 III")
-
-<p>Table:&nbsp;<code>Sales</code></p>
-
-<pre>
-+-------------+-------+
-| Column Name | Type  |
-+-------------+-------+
-| sale_id     | int   |
-| product_id  | int   |
-| year        | int   |
-| quantity    | int   |
-| price       | int   |
-+-------------+-------+
-sale_id is the primary key of this table.
-product_id is a foreign key to <code>Product</code> table.
-Note that the price is per unit.
-</pre>
-
-<p>Table:&nbsp;<code>Product</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| product_id   | int     |
-| product_name | varchar |
-+--------------+---------+
-product_id is the primary key of this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p style="direction: ltr;">Write an SQL query that selects the <strong>product id</strong>, <strong>year</strong>, <strong>quantity</strong>, and <strong>price</strong> for the <strong>first year</strong> of every product sold.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-<code>Sales</code> table:
-+---------+------------+------+----------+-------+
-| sale_id | product_id | year | quantity | price |
-+---------+------------+------+----------+-------+ 
-| 1       | 100        | 2008 | 10       | 5000  |
-| 2       | 100        | 2009 | 12       | 5000  |
-| 7       | 200        | 2011 | 15       | 9000  |
-+---------+------------+------+----------+-------+
-
-Product table:
-+------------+--------------+
-| product_id | product_name |
-+------------+--------------+
-| 100        | Nokia        |
-| 200        | Apple        |
-| 300        | Samsung      |
-+------------+--------------+
-
-Result table:
-+------------+------------+----------+-------+
-| product_id | first_year | quantity | price |
-+------------+------------+----------+-------+ 
-| 100        | 2008       | 10       | 5000  |
-| 200        | 2011       | 15       | 9000  |
-+------------+------------+----------+-------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Product Sales Analysis II](../product-sales-analysis-ii) (Easy)
diff --git a/problems/product-sales-analysis-iii/mysql_schemas.sql b/problems/product-sales-analysis-iii/mysql_schemas.sql
deleted file mode 100644
index 2d7632cb2..000000000
--- a/problems/product-sales-analysis-iii/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Sales (sale_id int, product_id int, year int, quantity int, price int);
-Create table If Not Exists Product (product_id int, product_name varchar(10));
-Truncate table Sales;
-insert into Sales (sale_id, product_id, year, quantity, price) values ('1', '100', '2008', '10', '5000');
-insert into Sales (sale_id, product_id, year, quantity, price) values ('2', '100', '2009', '12', '5000');
-insert into Sales (sale_id, product_id, year, quantity, price) values ('7', '200', '2011', '15', '9000');
-Truncate table Product;
-insert into Product (product_id, product_name) values ('100', 'Nokia');
-insert into Product (product_id, product_name) values ('200', 'Apple');
-insert into Product (product_id, product_name) values ('300', 'Samsung');
diff --git a/problems/product-sales-analysis-iii/product_sales_analysis_iii.sql b/problems/product-sales-analysis-iii/product_sales_analysis_iii.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/product-sales-analysis-iii/product_sales_analysis_iii.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/products-price-for-each-store/README.md b/problems/products-price-for-each-store/README.md
deleted file mode 100644
index ad3e0f768..000000000
--- a/problems/products-price-for-each-store/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../car-fleet-ii "Car Fleet II")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-path-in-a-hidden-grid "Shortest Path in a Hidden Grid")
-
-## [1777. Product's Price for Each Store (Easy)](https://leetcode.com/problems/products-price-for-each-store "每家商店的产品价格")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Rearrange Products Table](../rearrange-products-table) (Easy)
diff --git a/problems/products-price-for-each-store/mysql_schemas.sql b/problems/products-price-for-each-store/mysql_schemas.sql
deleted file mode 100644
index e1187f768..000000000
--- a/problems/products-price-for-each-store/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Products (product_id int, store ENUM('store1', 'store2', 'store3'), price int);
-Truncate table Products;
-insert into Products (product_id, store, price) values ('0', 'store1', '95');
-insert into Products (product_id, store, price) values ('0', 'store3', '105');
-insert into Products (product_id, store, price) values ('0', 'store2', '100');
-insert into Products (product_id, store, price) values ('1', 'store1', '70');
-insert into Products (product_id, store, price) values ('1', 'store3', '80');
diff --git a/problems/products-worth-over-invoices/README.md b/problems/products-worth-over-invoices/README.md
deleted file mode 100644
index a73a4de86..000000000
--- a/problems/products-worth-over-invoices/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lowest-common-ancestor-of-a-binary-tree-iv "Lowest Common Ancestor of a Binary Tree IV")
-　　　　　　　　　　　　　　　　
-[Next >](../goal-parser-interpretation "Goal Parser Interpretation")
-
-## [1677. Product's Worth Over Invoices (Easy)](https://leetcode.com/problems/products-worth-over-invoices "发票中的产品金额")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/products-worth-over-invoices/mysql_schemas.sql b/problems/products-worth-over-invoices/mysql_schemas.sql
deleted file mode 100644
index 42dfdb2b8..000000000
--- a/problems/products-worth-over-invoices/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Product(product_id int, name varchar(15));
-Create table If Not Exists Invoice(invoice_id int,product_id int,rest int, paid int, canceled int, refunded int);
-Truncate table Product;
-insert into Product (product_id, name) values ('0', 'ham');
-insert into Product (product_id, name) values ('1', 'bacon');
-Truncate table Invoice;
-insert into Invoice (invoice_id, product_id, rest, paid, canceled, refunded) values ('23', '0', '2', '0', '5', '0');
-insert into Invoice (invoice_id, product_id, rest, paid, canceled, refunded) values ('12', '0', '0', '4', '0', '3');
-insert into Invoice (invoice_id, product_id, rest, paid, canceled, refunded) values ('1', '1', '1', '1', '0', '1');
-insert into Invoice (invoice_id, product_id, rest, paid, canceled, refunded) values ('2', '1', '1', '0', '1', '1');
-insert into Invoice (invoice_id, product_id, rest, paid, canceled, refunded) values ('3', '1', '0', '1', '1', '1');
-insert into Invoice (invoice_id, product_id, rest, paid, canceled, refunded) values ('4', '1', '1', '1', '1', '0');
diff --git a/problems/profitable-schemes/README.md b/problems/profitable-schemes/README.md
deleted file mode 100644
index f5e1c053b..000000000
--- a/problems/profitable-schemes/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../nth-magical-number "Nth Magical Number")
-　　　　　　　　　　　　　　　　
-[Next >](../decoded-string-at-index "Decoded String at Index")
-
-## [879. Profitable Schemes (Hard)](https://leetcode.com/problems/profitable-schemes "盈利计划")
-
-<p>There is a group of <code>n</code> members, and a list of various crimes they could commit. The <code>i<sup>th</sup></code> crime generates a <code>profit[i]</code> and requires <code>group[i]</code> members to participate in it. If a member participates in one crime, that member can&#39;t participate in another crime.</p>
-
-<p>Let&#39;s call a <strong>profitable scheme</strong> any subset of these crimes that generates at least <code>minProfit</code> profit, and the total number of members participating in that subset of crimes is at most <code>n</code>.</p>
-
-<p>Return the number of schemes that can be chosen. Since the answer may be very large, <strong>return it modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, minProfit = 3, group = [2,2], profit = [2,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> To make a profit of at least 3, the group could either commit crimes 0 and 1, or just crime 1.
-In total, there are 2 schemes.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10, minProfit = 5, group = [2,3,5], profit = [6,7,8]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> To make a profit of at least 5, the group could commit any crimes, as long as they commit one.
-There are 7 possible schemes: (0), (1), (2), (0,1), (0,2), (1,2), and (0,1,2).</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>0 &lt;= minProfit &lt;= 100</code></li>
-	<li><code>1 &lt;= group.length &lt;= 100</code></li>
-	<li><code>1 &lt;= group[i] &lt;= 100</code></li>
-	<li><code>profit.length == group.length</code></li>
-	<li><code>0 &lt;= profit[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/profitable-schemes/profitable_schemes.go b/problems/profitable-schemes/profitable_schemes.go
deleted file mode 100644
index 4e0fcb0d0..000000000
--- a/problems/profitable-schemes/profitable_schemes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem879
diff --git a/problems/profitable-schemes/profitable_schemes_test.go b/problems/profitable-schemes/profitable_schemes_test.go
deleted file mode 100644
index 4e0fcb0d0..000000000
--- a/problems/profitable-schemes/profitable_schemes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem879
diff --git a/problems/project-employees-i/README.md b/problems/project-employees-i/README.md
deleted file mode 100644
index 663cffab8..000000000
--- a/problems/project-employees-i/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-submatrices-that-sum-to-target "Number of Submatrices That Sum to Target")
-　　　　　　　　　　　　　　　　
-[Next >](../project-employees-ii "Project Employees II")
-
-## [1075. Project Employees I (Easy)](https://leetcode.com/problems/project-employees-i "项目员工 I")
-
-<p>Table:&nbsp;<code>Project</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| project_id  | int     |
-| employee_id | int     |
-+-------------+---------+
-(project_id, employee_id) is the primary key of this table.
-employee_id is a foreign key to <code>Employee</code> table.
-</pre>
-
-<p>Table:&nbsp;<code>Employee</code></p>
-
-<pre>
-+------------------+---------+
-| Column Name      | Type    |
-+------------------+---------+
-| employee_id      | int     |
-| name             | varchar |
-| experience_years | int     |
-+------------------+---------+
-employee_id is the primary key of this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the <strong>average</strong>&nbsp;experience years of all the employees for each project, <strong>rounded to 2 digits</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Project table:
-+-------------+-------------+
-| project_id  | employee_id |
-+-------------+-------------+
-| 1           | 1           |
-| 1           | 2           |
-| 1           | 3           |
-| 2           | 1           |
-| 2           | 4           |
-+-------------+-------------+
-
-Employee table:
-+-------------+--------+------------------+
-| employee_id | name   | experience_years |
-+-------------+--------+------------------+
-| 1           | Khaled | 3                |
-| 2           | Ali    | 2                |
-| 3           | John   | 1                |
-| 4           | Doe    | 2                |
-+-------------+--------+------------------+
-
-Result table:
-+-------------+---------------+
-| project_id  | average_years |
-+-------------+---------------+
-| 1           | 2.00          |
-| 2           | 2.50          |
-+-------------+---------------+
-The average experience years for the first project is (3 + 2 + 1) / 3 = 2.00 and for the second project is (3 + 2) / 2 = 2.50
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Project Employees II](../project-employees-ii) (Easy)
diff --git a/problems/project-employees-i/mysql_schemas.sql b/problems/project-employees-i/mysql_schemas.sql
deleted file mode 100644
index 552b78497..000000000
--- a/problems/project-employees-i/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Project (project_id int, employee_id int);
-Create table If Not Exists Employee (employee_id int, name varchar(10), experience_years int);
-Truncate table Project;
-insert into Project (project_id, employee_id) values ('1', '1');
-insert into Project (project_id, employee_id) values ('1', '2');
-insert into Project (project_id, employee_id) values ('1', '3');
-insert into Project (project_id, employee_id) values ('2', '1');
-insert into Project (project_id, employee_id) values ('2', '4');
-Truncate table Employee;
-insert into Employee (employee_id, name, experience_years) values ('1', 'Khaled', '3');
-insert into Employee (employee_id, name, experience_years) values ('2', 'Ali', '2');
-insert into Employee (employee_id, name, experience_years) values ('3', 'John', '1');
-insert into Employee (employee_id, name, experience_years) values ('4', 'Doe', '2');
diff --git a/problems/project-employees-i/project_employees_i.sql b/problems/project-employees-i/project_employees_i.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/project-employees-i/project_employees_i.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/project-employees-ii/README.md b/problems/project-employees-ii/README.md
deleted file mode 100644
index bc5178900..000000000
--- a/problems/project-employees-ii/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../project-employees-i "Project Employees I")
-　　　　　　　　　　　　　　　　
-[Next >](../project-employees-iii "Project Employees III")
-
-## [1076. Project Employees II (Easy)](https://leetcode.com/problems/project-employees-ii "项目员工II")
-
-<p>Table:&nbsp;<code>Project</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| project_id  | int     |
-| employee_id | int     |
-+-------------+---------+
-(project_id, employee_id) is the primary key of this table.
-employee_id is a foreign key to <code>Employee</code> table.
-</pre>
-
-<p>Table:&nbsp;<code>Employee</code></p>
-
-<pre>
-+------------------+---------+
-| Column Name      | Type    |
-+------------------+---------+
-| employee_id      | int     |
-| name             | varchar |
-| experience_years | int     |
-+------------------+---------+
-employee_id is the primary key of this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports all the <strong>projects</strong>&nbsp;that have the most employees.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Project table:
-+-------------+-------------+
-| project_id  | employee_id |
-+-------------+-------------+
-| 1           | 1           |
-| 1           | 2           |
-| 1           | 3           |
-| 2           | 1           |
-| 2           | 4           |
-+-------------+-------------+
-
-Employee table:
-+-------------+--------+------------------+
-| employee_id | name   | experience_years |
-+-------------+--------+------------------+
-| 1           | Khaled | 3                |
-| 2           | Ali    | 2                |
-| 3           | John   | 1                |
-| 4           | Doe    | 2                |
-+-------------+--------+------------------+
-
-Result table:
-+-------------+
-| project_id  |
-+-------------+
-| 1           |
-+-------------+
-The first project has 3 employees while the second one has 2.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/project-employees-ii/mysql_schemas.sql b/problems/project-employees-ii/mysql_schemas.sql
deleted file mode 100644
index 552b78497..000000000
--- a/problems/project-employees-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Project (project_id int, employee_id int);
-Create table If Not Exists Employee (employee_id int, name varchar(10), experience_years int);
-Truncate table Project;
-insert into Project (project_id, employee_id) values ('1', '1');
-insert into Project (project_id, employee_id) values ('1', '2');
-insert into Project (project_id, employee_id) values ('1', '3');
-insert into Project (project_id, employee_id) values ('2', '1');
-insert into Project (project_id, employee_id) values ('2', '4');
-Truncate table Employee;
-insert into Employee (employee_id, name, experience_years) values ('1', 'Khaled', '3');
-insert into Employee (employee_id, name, experience_years) values ('2', 'Ali', '2');
-insert into Employee (employee_id, name, experience_years) values ('3', 'John', '1');
-insert into Employee (employee_id, name, experience_years) values ('4', 'Doe', '2');
diff --git a/problems/project-employees-ii/project_employees_ii.sql b/problems/project-employees-ii/project_employees_ii.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/project-employees-ii/project_employees_ii.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/project-employees-iii/README.md b/problems/project-employees-iii/README.md
deleted file mode 100644
index 6888a3376..000000000
--- a/problems/project-employees-iii/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../project-employees-ii "Project Employees II")
-　　　　　　　　　　　　　　　　
-[Next >](../occurrences-after-bigram "Occurrences After Bigram")
-
-## [1077. Project Employees III (Medium)](https://leetcode.com/problems/project-employees-iii "项目员工 III")
-
-<p>Table:&nbsp;<code>Project</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| project_id  | int     |
-| employee_id | int     |
-+-------------+---------+
-(project_id, employee_id) is the primary key of this table.
-employee_id is a foreign key to <code>Employee</code> table.
-</pre>
-
-<p>Table:&nbsp;<code>Employee</code></p>
-
-<pre>
-+------------------+---------+
-| Column Name      | Type    |
-+------------------+---------+
-| employee_id      | int     |
-| name             | varchar |
-| experience_years | int     |
-+------------------+---------+
-employee_id is the primary key of this table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the <strong>most experienced</strong> employees in each project. In case of a tie, report all employees with the maximum number of experience years.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Project table:
-+-------------+-------------+
-| project_id  | employee_id |
-+-------------+-------------+
-| 1           | 1           |
-| 1           | 2           |
-| 1           | 3           |
-| 2           | 1           |
-| 2           | 4           |
-+-------------+-------------+
-
-Employee table:
-+-------------+--------+------------------+
-| employee_id | name   | experience_years |
-+-------------+--------+------------------+
-| 1           | Khaled | 3                |
-| 2           | Ali    | 2                |
-| 3           | John   | 3                |
-| 4           | Doe    | 2                |
-+-------------+--------+------------------+
-
-Result table:
-+-------------+---------------+
-| project_id  | employee_id   |
-+-------------+---------------+
-| 1           | 1             |
-| 1           | 3             |
-| 2           | 1             |
-+-------------+---------------+
-Both employees with id 1 and 3 have the most experience among the employees of the first project. For the second project, the employee with id 1 has the most experience.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/project-employees-iii/mysql_schemas.sql b/problems/project-employees-iii/mysql_schemas.sql
deleted file mode 100644
index 7e21b2188..000000000
--- a/problems/project-employees-iii/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Project (project_id int, employee_id int);
-Create table If Not Exists Employee (employee_id int, name varchar(10), experience_years int);
-Truncate table Project;
-insert into Project (project_id, employee_id) values ('1', '1');
-insert into Project (project_id, employee_id) values ('1', '2');
-insert into Project (project_id, employee_id) values ('1', '3');
-insert into Project (project_id, employee_id) values ('2', '1');
-insert into Project (project_id, employee_id) values ('2', '4');
-Truncate table Employee;
-insert into Employee (employee_id, name, experience_years) values ('1', 'Khaled', '3');
-insert into Employee (employee_id, name, experience_years) values ('2', 'Ali', '2');
-insert into Employee (employee_id, name, experience_years) values ('3', 'John', '3');
-insert into Employee (employee_id, name, experience_years) values ('4', 'Doe', '2');
diff --git a/problems/project-employees-iii/project_employees_iii.sql b/problems/project-employees-iii/project_employees_iii.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/project-employees-iii/project_employees_iii.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/projection-area-of-3d-shapes/README.md b/problems/projection-area-of-3d-shapes/README.md
deleted file mode 100644
index 645e1c1af..000000000
--- a/problems/projection-area-of-3d-shapes/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reachable-nodes-in-subdivided-graph "Reachable Nodes In Subdivided Graph")
-　　　　　　　　　　　　　　　　
-[Next >](../uncommon-words-from-two-sentences "Uncommon Words from Two Sentences")
-
-## [883. Projection Area of 3D Shapes (Easy)](https://leetcode.com/problems/projection-area-of-3d-shapes "三维形体投影面积")
-
-<p>You are given an <code>n x n</code> <code>grid</code> where we place some <code>1 x 1 x 1</code> cubes that are axis-aligned with the <code>x</code>, <code>y</code>, and <code>z</code> axes.</p>
-
-<p>Each value <code>v = grid[i][j]</code> represents a tower of <code>v</code> cubes placed on top of the cell <code>(i, j)</code>.</p>
-
-<p>We view the projection of these cubes onto the <code>xy</code>, <code>yz</code>, and <code>zx</code> planes.</p>
-
-<p>A <strong>projection</strong> is like a shadow, that maps our <strong>3-dimensional</strong> figure to a <strong>2-dimensional</strong> plane. We are viewing the &quot;shadow&quot; when looking at the cubes from the top, the front, and the side.</p>
-
-<p>Return <em>the total area of all three projections</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/08/02/shadow.png" style="width: 800px; height: 214px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,2],[3,4]]
-<strong>Output:</strong> 17
-<strong>Explanation:</strong> Here are the three projections (&quot;shadows&quot;) of the shape made with each axis-aligned plane.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[2]]
-<strong>Output:</strong> 5
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,0],[0,2]]
-<strong>Output:</strong> 8
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length == grid[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 50</code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;= 50</code></li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/projection-area-of-3d-shapes/projection_area_of_3d_shapes.go b/problems/projection-area-of-3d-shapes/projection_area_of_3d_shapes.go
deleted file mode 100644
index 504f4d7ce..000000000
--- a/problems/projection-area-of-3d-shapes/projection_area_of_3d_shapes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem883
diff --git a/problems/projection-area-of-3d-shapes/projection_area_of_3d_shapes_test.go b/problems/projection-area-of-3d-shapes/projection_area_of_3d_shapes_test.go
deleted file mode 100644
index 504f4d7ce..000000000
--- a/problems/projection-area-of-3d-shapes/projection_area_of_3d_shapes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem883
diff --git a/problems/pseudo-palindromic-paths-in-a-binary-tree/README.md b/problems/pseudo-palindromic-paths-in-a-binary-tree/README.md
deleted file mode 100644
index 80f6d4723..000000000
--- a/problems/pseudo-palindromic-paths-in-a-binary-tree/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-vowels-in-a-substring-of-given-length "Maximum Number of Vowels in a Substring of Given Length")
-　　　　　　　　　　　　　　　　
-[Next >](../max-dot-product-of-two-subsequences "Max Dot Product of Two Subsequences")
-
-## [1457. Pseudo-Palindromic Paths in a Binary Tree (Medium)](https://leetcode.com/problems/pseudo-palindromic-paths-in-a-binary-tree "二叉树中的伪回文路径")
-
-<p>Given a binary tree where node values are digits from 1 to 9. A path in the binary tree is said to be <strong>pseudo-palindromic</strong> if at least one permutation of the node values in the path is a palindrome.</p>
-
-<p><em>Return the number of <strong>pseudo-palindromic</strong> paths going from the root node to leaf nodes.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2020/05/06/palindromic_paths_1.png" style="width: 300px; height: 201px;" /></p>
-
-<pre>
-<strong>Input:</strong> root = [2,3,1,3,1,null,1]
-<strong>Output:</strong> 2 
-<strong>Explanation:</strong> The figure above represents the given binary tree. There are three paths going from the root node to leaf nodes: the red path [2,3,3], the green path [2,1,1], and the path [2,3,1]. Among these paths only red path and green path are pseudo-palindromic paths since the red path [2,3,3] can be rearranged in [3,2,3] (palindrome) and the green path [2,1,1] can be rearranged in [1,2,1] (palindrome).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/05/07/palindromic_paths_2.png" style="width: 300px; height: 314px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> root = [2,1,1,1,3,null,null,null,null,null,1]
-<strong>Output:</strong> 1 
-<strong>Explanation:</strong> The figure above represents the given binary tree. There are three paths going from the root node to leaf nodes: the green path [2,1,1], the path [2,1,3,1], and the path [2,1]. Among these paths only the green path is pseudo-palindromic since [2,1,1] can be rearranged in [1,2,1] (palindrome).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [9]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that the node values of a path form a palindrome if at most one digit has an odd frequency (parity).
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a Depth First Search (DFS) keeping the frequency (parity) of the digits. Once you are in a leaf node check if at most one digit has an odd frequency (parity).
-</details>
diff --git a/problems/push-dominoes/README.md b/problems/push-dominoes/README.md
deleted file mode 100644
index 2d7a28c6f..000000000
--- a/problems/push-dominoes/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../new-21-game "New 21 Game")
-　　　　　　　　　　　　　　　　
-[Next >](../similar-string-groups "Similar String Groups")
-
-## [838. Push Dominoes (Medium)](https://leetcode.com/problems/push-dominoes "推多米诺")
-
-<p>There are <code>n</code> dominoes in a line, and we place each domino vertically upright. In the beginning, we simultaneously push some of the dominoes either to the left or to the right.</p>
-
-<p>After each second, each domino that is falling to the left pushes the adjacent domino on the left. Similarly, the dominoes falling to the right push their adjacent dominoes standing on the right.</p>
-
-<p>When a vertical domino has dominoes falling on it from both sides, it stays still due to the balance of the forces.</p>
-
-<p>For the purposes of this question, we will consider that a falling domino expends no additional force to a falling or already fallen domino.</p>
-
-<p>You are given a string <code>dominoes</code> representing the initial state where:</p>
-
-<ul>
-	<li><code>dominoes[i] = &#39;L&#39;</code>, if the <code>i<sup>th</sup></code> domino has been pushed to the left,</li>
-	<li><code>dominoes[i] = &#39;R&#39;</code>, if the <code>i<sup>th</sup></code> domino has been pushed to the right, and</li>
-	<li><code>dominoes[i] = &#39;.&#39;</code>, if the <code>i<sup>th</sup></code> domino has not been pushed.</li>
-</ul>
-
-<p>Return <em>a string representing the final state</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> dominoes = &quot;RR.L&quot;
-<strong>Output:</strong> &quot;RR.L&quot;
-<strong>Explanation:</strong> The first domino expends no additional force on the second domino.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/05/18/domino.png" style="height: 196px; width: 512px;" />
-<pre>
-<strong>Input:</strong> dominoes = &quot;.L.R...LR..L..&quot;
-<strong>Output:</strong> &quot;LL.RR.LLRRLL..&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == dominoes.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>dominoes[i]</code> is either <code>&#39;L&#39;</code>, <code>&#39;R&#39;</code>, or <code>&#39;.&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/push-dominoes/push_dominoes.go b/problems/push-dominoes/push_dominoes.go
deleted file mode 100644
index ca0edd34a..000000000
--- a/problems/push-dominoes/push_dominoes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem838
diff --git a/problems/push-dominoes/push_dominoes_test.go b/problems/push-dominoes/push_dominoes_test.go
deleted file mode 100644
index ca0edd34a..000000000
--- a/problems/push-dominoes/push_dominoes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem838
diff --git a/problems/put-boxes-into-the-warehouse-i/README.md b/problems/put-boxes-into-the-warehouse-i/README.md
deleted file mode 100644
index a1d6f02d4..000000000
--- a/problems/put-boxes-into-the-warehouse-i/README.md
+++ /dev/null
@@ -1,25 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stone-game-v "Stone Game V")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-orders-and-customers-per-month "Unique Orders and Customers Per Month")
-
-## [1564. Put Boxes Into the Warehouse I (Medium)](https://leetcode.com/problems/put-boxes-into-the-warehouse-i "把箱子放进仓库里 I")
-
-
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the boxes in ascending order, try to process the box with the smallest height first.
-</details>
diff --git a/problems/put-boxes-into-the-warehouse-ii/README.md b/problems/put-boxes-into-the-warehouse-ii/README.md
deleted file mode 100644
index 467663579..000000000
--- a/problems/put-boxes-into-the-warehouse-ii/README.md
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-max-number-of-edges-to-keep-graph-fully-traversable "Remove Max Number of Edges to Keep Graph Fully Traversable")
-　　　　　　　　　　　　　　　　
-[Next >](../customer-who-visited-but-did-not-make-any-transactions "Customer Who Visited but Did Not Make Any Transactions")
-
-## [1580. Put Boxes Into the Warehouse II (Medium)](https://leetcode.com/problems/put-boxes-into-the-warehouse-ii "把箱子放进仓库里 II")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Put Boxes Into the Warehouse I](../put-boxes-into-the-warehouse-i) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to put at least one box in the house pushing it from either side.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Once you put one box to the house, you can solve the problem with the same logic used to solve version I. You have a warehouse open from the left only and a warehouse open from the right only.
-</details>
diff --git a/problems/pyramid-transition-matrix/README.md b/problems/pyramid-transition-matrix/README.md
deleted file mode 100644
index d34c72d79..000000000
--- a/problems/pyramid-transition-matrix/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pour-water "Pour Water")
-　　　　　　　　　　　　　　　　
-[Next >](../set-intersection-size-at-least-two "Set Intersection Size At Least Two")
-
-## [756. Pyramid Transition Matrix (Medium)](https://leetcode.com/problems/pyramid-transition-matrix "金字塔转换矩阵")
-
-<p>We are stacking blocks to form a pyramid. Each block has a color which is a one-letter string.</p>
-
-<p>We are allowed to place any color block <code>C</code> on top of two adjacent blocks of colors <code>A</code> and <code>B</code>, if and only if <code>ABC</code> is an allowed triple.</p>
-
-<p>We start with a bottom row of <code>bottom</code>, represented as a single string. We also start with a list of allowed triples <code>allowed</code>. Each allowed triple is represented as a string of length <code>3</code>.</p>
-
-<p>Return <code>true</code> <em>if we can build the pyramid all the way to the top, otherwise</em> <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/26/pyramid1-grid.jpg" style="width: 600px; height: 232px;" />
-<pre>
-<strong>Input:</strong> bottom = &quot;BCD&quot;, allowed = [&quot;BCC&quot;,&quot;CDE&quot;,&quot;CEA&quot;,&quot;FFF&quot;]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The allowed stacks are shown on the right.
-Starting from the bottom (level 3), we can build &quot;CE&quot; on level 2 and then build &quot;E&quot; on level 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/26/pyramid2-grid.jpg" style="width: 600px; height: 359px;" />
-<pre>
-<strong>Input:</strong> bottom = &quot;AAAA&quot;, allowed = [&quot;AAB&quot;,&quot;AAC&quot;,&quot;BCD&quot;,&quot;BBE&quot;,&quot;DEF&quot;]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The allowed stacks are shown on the right.
-Starting from the bottom (level 4), there are multiple ways to build level 3 but trying all the possibilites, you will get always stuck before building level 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= bottom.length &lt;= 6</code></li>
-	<li><code>0 &lt;= allowed.length &lt;= 216</code></li>
-	<li><code>allowed[i].length == 3</code></li>
-	<li>The letters in all input strings are from the set <code>{&#39;A&#39;, &#39;B&#39;, &#39;C&#39;, &#39;D&#39;, &#39;E&#39;, &#39;F&#39;}</code>.</li>
-	<li>All the values of <code>allowed</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
diff --git a/problems/pyramid-transition-matrix/pyramid_transition_matrix.go b/problems/pyramid-transition-matrix/pyramid_transition_matrix.go
deleted file mode 100644
index a685cb849..000000000
--- a/problems/pyramid-transition-matrix/pyramid_transition_matrix.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem756
diff --git a/problems/pyramid-transition-matrix/pyramid_transition_matrix_test.go b/problems/pyramid-transition-matrix/pyramid_transition_matrix_test.go
deleted file mode 100644
index a685cb849..000000000
--- a/problems/pyramid-transition-matrix/pyramid_transition_matrix_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem756
diff --git a/problems/queens-that-can-attack-the-king/README.md b/problems/queens-that-can-attack-the-king/README.md
deleted file mode 100644
index 9c4914988..000000000
--- a/problems/queens-that-can-attack-the-king/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-a-string-in-balanced-strings "Split a String in Balanced Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../dice-roll-simulation "Dice Roll Simulation")
-
-## [1222. Queens That Can Attack the King (Medium)](https://leetcode.com/problems/queens-that-can-attack-the-king "可以攻击国王的皇后")
-
-<p>On an <strong>8x8</strong> chessboard, there can be multiple Black Queens and one White King.</p>
-
-<p>Given an array of integer coordinates <code>queens</code> that represents the positions of the Black Queens, and a pair of coordinates <code>king</code> that represent the position of the White King, return the coordinates of all the queens (in any order) that can attack the King.</p>
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/01/untitled-diagram.jpg" style="width: 321px; height: 321px;" /></p>
-
-<pre>
-<strong>Input:</strong> queens = [[0,1],[1,0],[4,0],[0,4],[3,3],[2,4]], king = [0,0]
-<strong>Output:</strong> [[0,1],[1,0],[3,3]]
-<strong>Explanation:</strong>&nbsp; 
-The queen at [0,1] can attack the king cause they&#39;re in the same row. 
-The queen at [1,0] can attack the king cause they&#39;re in the same column. 
-The queen at [3,3] can attack the king cause they&#39;re in the same diagnal. 
-The queen at [0,4] can&#39;t attack the king cause it&#39;s blocked by the queen at [0,1]. 
-The queen at [4,0] can&#39;t attack the king cause it&#39;s blocked by the queen at [1,0]. 
-The queen at [2,4] can&#39;t attack the king cause it&#39;s not in the same row/column/diagnal as the king.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/10/01/untitled-diagram-1.jpg" style="width: 321px; height: 321px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> queens = [[0,0],[1,1],[2,2],[3,4],[3,5],[4,4],[4,5]], king = [3,3]
-<strong>Output:</strong> [[2,2],[3,4],[4,4]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/10/01/untitled-diagram-2.jpg" style="width: 321px; height: 321px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> queens = [[5,6],[7,7],[2,1],[0,7],[1,6],[5,1],[3,7],[0,3],[4,0],[1,2],[6,3],[5,0],[0,4],[2,2],[1,1],[6,4],[5,4],[0,0],[2,6],[4,5],[5,2],[1,4],[7,5],[2,3],[0,5],[4,2],[1,0],[2,7],[0,1],[4,6],[6,1],[0,6],[4,3],[1,7]], king = [3,4]
-<strong>Output:</strong> [[2,3],[1,4],[1,6],[3,7],[4,3],[5,4],[4,5]]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= queens.length&nbsp;&lt;= 63</code></li>
-	<li><code>queens[i].length == 2</code></li>
-	<li><code>0 &lt;= queens[i][j] &lt;&nbsp;8</code></li>
-	<li><code>king.length == 2</code></li>
-	<li><code>0 &lt;= king[0], king[1] &lt; 8</code></li>
-	<li>At most one piece is allowed in a cell.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check 8 directions around the King.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the nearest queen in each direction.
-</details>
diff --git a/problems/queries-on-a-permutation-with-key/README.md b/problems/queries-on-a-permutation-with-key/README.md
deleted file mode 100644
index d1f4999c2..000000000
--- a/problems/queries-on-a-permutation-with-key/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../string-matching-in-an-array "String Matching in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../html-entity-parser "HTML Entity Parser")
-
-## [1409. Queries on a Permutation With Key (Medium)](https://leetcode.com/problems/queries-on-a-permutation-with-key "查询带键的排列")
-
-<p>Given the array <code>queries</code> of positive integers between <code>1</code> and <code>m</code>, you have to process all <code>queries[i]</code> (from <code>i=0</code> to <code>i=queries.length-1</code>) according to the following rules:</p>
-
-<ul>
-	<li>In the beginning, you have the permutation <code>P=[1,2,3,...,m]</code>.</li>
-	<li>For the current <code>i</code>, find the position of <code>queries[i]</code> in the permutation <code>P</code> (<strong>indexing from 0</strong>) and then move this at the beginning of the permutation <code>P.</code>&nbsp;Notice that the position of <code>queries[i]</code> in <code>P</code> is the result for <code>queries[i]</code>.</li>
-</ul>
-
-<p>Return an array containing the result for the given <code>queries</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [3,1,2,1], m = 5
-<strong>Output:</strong> [2,1,2,1] 
-<strong>Explanation:</strong> The queries are processed as follow: 
-For i=0: queries[i]=3, P=[1,2,3,4,5], position of 3 in P is <strong>2</strong>, then we move 3 to the beginning of P resulting in P=[3,1,2,4,5]. 
-For i=1: queries[i]=1, P=[3,1,2,4,5], position of 1 in P is <strong>1</strong>, then we move 1 to the beginning of P resulting in P=[1,3,2,4,5]. 
-For i=2: queries[i]=2, P=[1,3,2,4,5], position of 2 in P is <strong>2</strong>, then we move 2 to the beginning of P resulting in P=[2,1,3,4,5]. 
-For i=3: queries[i]=1, P=[2,1,3,4,5], position of 1 in P is <strong>1</strong>, then we move 1 to the beginning of P resulting in P=[1,2,3,4,5]. 
-Therefore, the array containing the result is [2,1,2,1].  
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [4,1,2,2], m = 4
-<strong>Output:</strong> [3,1,2,0]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> queries = [7,5,5,8,3], m = 8
-<strong>Output:</strong> [6,5,0,7,5]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m &lt;= 10^3</code></li>
-	<li><code>1 &lt;= queries.length &lt;= m</code></li>
-	<li><code>1 &lt;= queries[i] &lt;= m</code></li>
-</ul>
-
-### Related Topics
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create the permutation P=[1,2,...,m], it could be a list for example.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each i, find the position of queries[i] with a simple scan over P and then move this to the beginning.
-</details>
diff --git a/problems/queries-on-number-of-points-inside-a-circle/README.md b/problems/queries-on-number-of-points-inside-a-circle/README.md
deleted file mode 100644
index 1ab1e0aab..000000000
--- a/problems/queries-on-number-of-points-inside-a-circle/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-operations-to-make-the-array-increasing "Minimum Operations to Make the Array Increasing")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-xor-for-each-query "Maximum XOR for Each Query")
-
-## [1828. Queries on Number of Points Inside a Circle (Medium)](https://leetcode.com/problems/queries-on-number-of-points-inside-a-circle "统计一个圆中点的数目")
-
-<p>You are given an array <code>points</code> where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> is the coordinates of the <code>i<sup>th</sup></code> point on a 2D plane. Multiple points can have the <strong>same</strong> coordinates.</p>
-
-<p>You are also given an array <code>queries</code> where <code>queries[j] = [x<sub>j</sub>, y<sub>j</sub>, r<sub>j</sub>]</code> describes a circle centered at <code>(x<sub>j</sub>, y<sub>j</sub>)</code> with a radius of <code>r<sub>j</sub></code>.</p>
-
-<p>For each query <code>queries[j]</code>, compute the number of points <strong>inside</strong> the <code>j<sup>th</sup></code> circle. Points <strong>on the border</strong> of the circle are considered <strong>inside</strong>.</p>
-
-<p>Return <em>an array </em><code>answer</code><em>, where </em><code>answer[j]</code><em> is the answer to the </em><code>j<sup>th</sup></code><em> query</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/25/chrome_2021-03-25_22-34-16.png" style="width: 500px; height: 418px;" />
-<pre>
-<strong>Input:</strong> points = [[1,3],[3,3],[5,3],[2,2]], queries = [[2,3,1],[4,3,1],[1,1,2]]
-<strong>Output:</strong> [3,2,2]
-<b>Explanation: </b>The points and circles are shown above.
-queries[0] is the green circle, queries[1] is the red circle, and queries[2] is the blue circle.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/25/chrome_2021-03-25_22-42-07.png" style="width: 500px; height: 390px;" />
-<pre>
-<strong>Input:</strong> points = [[1,1],[2,2],[3,3],[4,4],[5,5]], queries = [[1,2,2],[2,2,2],[4,3,2],[4,3,3]]
-<strong>Output:</strong> [2,3,2,4]
-<b>Explanation: </b>The points and circles are shown above.
-queries[0] is green, queries[1] is red, queries[2] is blue, and queries[3] is purple.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= points.length &lt;= 500</code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>​​​​​​i</sub>, y<sub>​​​​​​i</sub> &lt;= 500</code></li>
-	<li><code>1 &lt;= queries.length &lt;= 500</code></li>
-	<li><code>queries[j].length == 3</code></li>
-	<li><code>0 &lt;= x<sub>j</sub>, y<sub>j</sub> &lt;= 500</code></li>
-	<li><code>1 &lt;= r<sub>j</sub> &lt;= 500</code></li>
-	<li>All coordinates are integers.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you find the answer for each query in better complexity than <code>O(n)</code>?</p>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For a point to be inside a circle, the euclidean distance between it and the circle's center needs to be less than or equal to the radius.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Brute force for each circle and iterate overall points and find those inside it.
-</details>
diff --git a/problems/queries-quality-and-percentage/README.md b/problems/queries-quality-and-percentage/README.md
deleted file mode 100644
index a856dd542..000000000
--- a/problems/queries-quality-and-percentage/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-moves-to-reach-target-with-rotations "Minimum Moves to Reach Target with Rotations")
-　　　　　　　　　　　　　　　　
-[Next >](../team-scores-in-football-tournament "Team Scores in Football Tournament")
-
-## [1211. Queries Quality and Percentage (Easy)](https://leetcode.com/problems/queries-quality-and-percentage "查询结果的质量和占比")
-
-<p>Table: <code>Queries</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| query_name  | varchar |
-| result      | varchar |
-| position    | int     |
-| rating      | int     |
-+-------------+---------+
-There is no primary key for this table, it may have duplicate rows.
-This table contains information collected from some queries on a database.
-The <code>position</code> column has a value from <strong>1</strong> to <strong>500</strong>.
-The <code>rating</code> column has a value from <strong>1</strong> to <strong>5</strong>. Query with <code>rating</code> less than 3 is a poor query.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>We define query <code>quality</code> as:</p>
-
-<blockquote>
-<p>The average of the ratio between query rating and its position.</p>
-</blockquote>
-
-<p>We also define <code>poor query percentage</code> as:</p>
-
-<blockquote>
-<p>The percentage of all queries with rating less than 3.</p>
-</blockquote>
-
-<p>Write an SQL query to find each&nbsp;<code>query_name</code>, the <code>quality</code> and <code>poor_query_percentage</code>.</p>
-
-<p>Both <code>quality</code> and <code>poor_query_percentage</code> should be <strong>rounded to 2 decimal places</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Queries table:
-+------------+-------------------+----------+--------+
-| query_name | result            | position | rating |
-+------------+-------------------+----------+--------+
-| Dog        | Golden Retriever  | 1        | 5      |
-| Dog        | German Shepherd   | 2        | 5      |
-| Dog        | Mule              | 200      | 1      |
-| Cat        | Shirazi           | 5        | 2      |
-| Cat        | Siamese           | 3        | 3      |
-| Cat        | Sphynx            | 7        | 4      |
-+------------+-------------------+----------+--------+
-
-Result table:
-+------------+---------+-----------------------+
-| query_name | quality | poor_query_percentage |
-+------------+---------+-----------------------+
-| Dog        | 2.50    | 33.33                 |
-| Cat        | 0.66    | 33.33                 |
-+------------+---------+-----------------------+
-
-Dog queries quality is ((5 / 1) + (5 / 2) + (1 / 200)) / 3 = 2.50
-Dog queries poor_ query_percentage is (1 / 3) * 100 = 33.33
-
-Cat queries quality equals ((2 / 5) + (3 / 3) + (4 / 7)) / 3 = 0.66
-Cat queries poor_ query_percentage is (1 / 3) * 100 = 33.33
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Percentage of Users Attended a Contest](../percentage-of-users-attended-a-contest) (Easy)
diff --git a/problems/queries-quality-and-percentage/mysql_schemas.sql b/problems/queries-quality-and-percentage/mysql_schemas.sql
deleted file mode 100644
index 01ae2d169..000000000
--- a/problems/queries-quality-and-percentage/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Queries (query_name varchar(30), result varchar(50), position int, rating int);
-Truncate table Queries;
-insert into Queries (query_name, result, position, rating) values ('Dog', 'Golden Retriever', '1', '5');
-insert into Queries (query_name, result, position, rating) values ('Dog', 'German Shepherd', '2', '5');
-insert into Queries (query_name, result, position, rating) values ('Dog', 'Mule', '200', '1');
-insert into Queries (query_name, result, position, rating) values ('Cat', 'Shirazi', '5', '2');
-insert into Queries (query_name, result, position, rating) values ('Cat', 'Siamese', '3', '3');
-insert into Queries (query_name, result, position, rating) values ('Cat', 'Sphynx', '7', '4');
diff --git a/problems/queue-reconstruction-by-height/README.md b/problems/queue-reconstruction-by-height/README.md
deleted file mode 100644
index 7045e7aa1..000000000
--- a/problems/queue-reconstruction-by-height/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-a-number-to-hexadecimal "Convert a Number to Hexadecimal")
-　　　　　　　　　　　　　　　　
-[Next >](../trapping-rain-water-ii "Trapping Rain Water II")
-
-## [406. Queue Reconstruction by Height (Medium)](https://leetcode.com/problems/queue-reconstruction-by-height "根据身高重建队列")
-
-<p>You are given an array of people, <code>people</code>, which are the attributes of some people in a queue (not necessarily in order). Each <code>people[i] = [h<sub>i</sub>, k<sub>i</sub>]</code> represents the <code>i<sup>th</sup></code> person of height <code>h<sub>i</sub></code> with <strong>exactly</strong> <code>k<sub>i</sub></code> other people in front who have a height greater than or equal to <code>h<sub>i</sub></code>.</p>
-
-<p>Reconstruct and return <em>the queue that is represented by the input array </em><code>people</code>. The returned queue should be formatted as an array <code>queue</code>, where <code>queue[j] = [h<sub>j</sub>, k<sub>j</sub>]</code> is the attributes of the <code>j<sup>th</sup></code> person in the queue (<code>queue[0]</code> is the person at the front of the queue).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> people = [[7,0],[4,4],[7,1],[5,0],[6,1],[5,2]]
-<strong>Output:</strong> [[5,0],[7,0],[5,2],[6,1],[4,4],[7,1]]
-<strong>Explanation:</strong>
-Person 0 has height 5 with no other people taller or the same height in front.
-Person 1 has height 7 with no other people taller or the same height in front.
-Person 2 has height 5 with two persons taller or the same height in front, which is person 0 and 1.
-Person 3 has height 6 with one person taller or the same height in front, which is person 1.
-Person 4 has height 4 with four people taller or the same height in front, which are people 0, 1, 2, and 3.
-Person 5 has height 7 with one person taller or the same height in front, which is person 1.
-Hence [[5,0],[7,0],[5,2],[6,1],[4,4],[7,1]] is the reconstructed queue.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> people = [[6,0],[5,0],[4,0],[3,2],[2,2],[1,4]]
-<strong>Output:</strong> [[4,0],[5,0],[2,2],[3,2],[1,4],[6,0]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= people.length &lt;= 2000</code></li>
-	<li><code>0 &lt;= h<sub>i</sub> &lt;= 10<sup>6</sup></code></li>
-	<li><code>0 &lt;= k<sub>i</sub> &lt; people.length</code></li>
-	<li>It is guaranteed that the queue can be reconstructed.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Count of Smaller Numbers After Self](../count-of-smaller-numbers-after-self) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What can you say about the position of the shortest person? </br>
-If the position of the shortest person is <i>i</i>, how many people would be in front of the shortest person?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Once you fix the position of the shortest person, what can you say about the position of the second shortest person?
-</details>
diff --git a/problems/queue-reconstruction-by-height/queue_reconstruction_by_height.go b/problems/queue-reconstruction-by-height/queue_reconstruction_by_height.go
deleted file mode 100644
index 9036961c6..000000000
--- a/problems/queue-reconstruction-by-height/queue_reconstruction_by_height.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem406
diff --git a/problems/queue-reconstruction-by-height/queue_reconstruction_by_height_test.go b/problems/queue-reconstruction-by-height/queue_reconstruction_by_height_test.go
deleted file mode 100644
index 9036961c6..000000000
--- a/problems/queue-reconstruction-by-height/queue_reconstruction_by_height_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem406
diff --git a/problems/rabbits-in-forest/README.md b/problems/rabbits-in-forest/README.md
deleted file mode 100644
index 5e6e5e227..000000000
--- a/problems/rabbits-in-forest/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reaching-points "Reaching Points")
-　　　　　　　　　　　　　　　　
-[Next >](../transform-to-chessboard "Transform to Chessboard")
-
-## [781. Rabbits in Forest (Medium)](https://leetcode.com/problems/rabbits-in-forest "森林中的兔子")
-
-<p>There is a forest with an unknown number of rabbits. We asked n rabbits <strong>&quot;How many rabbits have the same color as you?&quot;</strong> and collected the answers in an integer array <code>answers</code> where <code>answers[i]</code> is the answer of the <code>i<sup>th</sup></code> rabbit.</p>
-
-<p>Given the array <code>answers</code>, return <em>the minimum number of rabbits that could be in the forest</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> answers = [1,1,2]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong>
-The two rabbits that answered &quot;1&quot; could both be the same color, say red.
-The rabbit that answered &quot;2&quot; can&#39;t be red or the answers would be inconsistent.
-Say the rabbit that answered &quot;2&quot; was blue.
-Then there should be 2 other blue rabbits in the forest that didn&#39;t answer into the array.
-The smallest possible number of rabbits in the forest is therefore 5: 3 that answered plus 2 that didn&#39;t.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> answers = [10,10,10]
-<strong>Output:</strong> 11
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= answers.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= answers[i] &lt; 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/rabbits-in-forest/rabbits_in_forest.go b/problems/rabbits-in-forest/rabbits_in_forest.go
deleted file mode 100644
index 80863126c..000000000
--- a/problems/rabbits-in-forest/rabbits_in_forest.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem781
diff --git a/problems/rabbits-in-forest/rabbits_in_forest_test.go b/problems/rabbits-in-forest/rabbits_in_forest_test.go
deleted file mode 100644
index 80863126c..000000000
--- a/problems/rabbits-in-forest/rabbits_in_forest_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem781
diff --git a/problems/race-car/README.md b/problems/race-car/README.md
deleted file mode 100644
index f0097cbbb..000000000
--- a/problems/race-car/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../linked-list-components "Linked List Components")
-　　　　　　　　　　　　　　　　
-[Next >](../most-common-word "Most Common Word")
-
-## [818. Race Car (Hard)](https://leetcode.com/problems/race-car "赛车")
-
-<p>Your car starts at position <code>0</code> and speed <code>+1</code> on an infinite number line. Your car can go into negative positions. Your car drives automatically according to a sequence of instructions <code>&#39;A&#39;</code> (accelerate) and <code>&#39;R&#39;</code> (reverse):</p>
-
-<ul>
-	<li>When you get an instruction <code>&#39;A&#39;</code>, your car does the following:
-	<ul>
-		<li><code>position += speed</code></li>
-		<li><code>speed *= 2</code></li>
-	</ul>
-	</li>
-	<li>When you get an instruction <code>&#39;R&#39;</code>, your car does the following:
-	<ul>
-		<li>If your speed is positive then <code>speed = -1</code></li>
-		<li>otherwise <code>speed = 1</code></li>
-	</ul>
-	Your position stays the same.</li>
-</ul>
-
-<p>For example, after commands <code>&quot;AAR&quot;</code>, your car goes to positions <code>0 --&gt; 1 --&gt; 3 --&gt; 3</code>, and your speed goes to <code>1 --&gt; 2 --&gt; 4 --&gt; -1</code>.</p>
-
-<p>Given a target position <code>target</code>, return <em>the length of the shortest sequence of instructions to get there</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-The shortest instruction sequence is &quot;AA&quot;.
-Your position goes from 0 --&gt; 1 --&gt; 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 6
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> 
-The shortest instruction sequence is &quot;AAARA&quot;.
-Your position goes from 0 --&gt; 1 --&gt; 3 --&gt; 7 --&gt; 7 --&gt; 6.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= target &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/race-car/race_car.go b/problems/race-car/race_car.go
deleted file mode 100644
index 74a669fc3..000000000
--- a/problems/race-car/race_car.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem818
diff --git a/problems/race-car/race_car_test.go b/problems/race-car/race_car_test.go
deleted file mode 100644
index 74a669fc3..000000000
--- a/problems/race-car/race_car_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem818
diff --git a/problems/random-flip-matrix/README.md b/problems/random-flip-matrix/README.md
deleted file mode 100644
index 6af8b4746..000000000
--- a/problems/random-flip-matrix/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../coin-change-2 "Coin Change 2")
-　　　　　　　　　　　　　　　　
-[Next >](../detect-capital "Detect Capital")
-
-## [519. Random Flip Matrix (Medium)](https://leetcode.com/problems/random-flip-matrix "随机翻转矩阵")
-
-<p>There is an <code>m x n</code> binary grid <code>matrix</code> with all the values set <code>0</code> initially. Design an algorithm to randomly pick an index <code>(i, j)</code> where <code>matrix[i][j] == 0</code> and flips it to <code>1</code>. All the indices <code>(i, j)</code> where <code>matrix[i][j] == 0</code> should be equally likely to be returned.</p>
-
-<p>Optimize your algorithm to minimize the number of calls made to the <strong>built-in</strong> random function of your language and optimize the time and space complexity.</p>
-
-<p>Implement the <code>Solution</code> class:</p>
-
-<ul>
-	<li><code>Solution(int m, int n)</code> Initializes the object with the size of the binary matrix <code>m</code> and <code>n</code>.</li>
-	<li><code>int[] flip()</code> Returns a random index <code>[i, j]</code> of the matrix where <code>matrix[i][j] == 0</code> and flips it to <code>1</code>.</li>
-	<li><code>void reset()</code> Resets all the values of the matrix to be <code>0</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Solution&quot;, &quot;flip&quot;, &quot;flip&quot;, &quot;flip&quot;, &quot;reset&quot;, &quot;flip&quot;]
-[[3, 1], [], [], [], [], []]
-<strong>Output</strong>
-[null, [1, 0], [2, 0], [0, 0], null, [2, 0]]
-
-<strong>Explanation</strong>
-Solution solution = new Solution(3, 1);
-solution.flip();  // return [1, 0], [0,0], [1,0], and [2,0] should be equally likely to be returned.
-solution.flip();  // return [2, 0], Since [1,0] was returned, [2,0] and [0,0]
-solution.flip();  // return [0, 0], Based on the previously returned indices, only [0,0] can be returned.
-solution.reset(); // All the values are reset to 0 and can be returned.
-solution.flip();  // return [2, 0], [0,0], [1,0], and [2,0] should be equally likely to be returned.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m, n &lt;= 10<sup>4</sup></code></li>
-	<li>There will be at least one free cell for each call to <code>flip</code>.</li>
-	<li>At most <code>1000</code> calls will be made to <code>flip</code> and <code>reset</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Reservoir Sampling](../../tag/reservoir-sampling/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
diff --git a/problems/random-flip-matrix/random_flip_matrix.go b/problems/random-flip-matrix/random_flip_matrix.go
deleted file mode 100644
index 9bac0023f..000000000
--- a/problems/random-flip-matrix/random_flip_matrix.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem519
diff --git a/problems/random-flip-matrix/random_flip_matrix_test.go b/problems/random-flip-matrix/random_flip_matrix_test.go
deleted file mode 100644
index 9bac0023f..000000000
--- a/problems/random-flip-matrix/random_flip_matrix_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem519
diff --git a/problems/random-pick-index/README.md b/problems/random-pick-index/README.md
deleted file mode 100644
index 8a120eb57..000000000
--- a/problems/random-pick-index/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../integer-replacement "Integer Replacement")
-　　　　　　　　　　　　　　　　
-[Next >](../evaluate-division "Evaluate Division")
-
-## [398. Random Pick Index (Medium)](https://leetcode.com/problems/random-pick-index "随机数索引")
-
-<p>Given an integer array <code>nums</code> with possible <strong>duplicates</strong>, randomly output the index of a given <code>target</code> number. You can assume that the given target number must exist in the array.</p>
-
-<p>Implement the <code>Solution</code> class:</p>
-
-<ul>
-	<li><code>Solution(int[] nums)</code> Initializes the object with the array <code>nums</code>.</li>
-	<li><code>int pick(int target)</code> Picks a random index <code>i</code> from <code>nums</code> where <code>nums[i] == target</code>. If there are multiple valid i&#39;s, then each index should have an equal probability of returning.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Solution&quot;, &quot;pick&quot;, &quot;pick&quot;, &quot;pick&quot;]
-[[[1, 2, 3, 3, 3]], [3], [1], [3]]
-<strong>Output</strong>
-[null, 4, 0, 2]
-
-<strong>Explanation</strong>
-Solution solution = new Solution([1, 2, 3, 3, 3]);
-solution.pick(3); // It should return either index 2, 3, or 4 randomly. Each index should have equal probability of returning.
-solution.pick(1); // It should return 0. Since in the array only nums[0] is equal to 1.
-solution.pick(3); // It should return either index 2, 3, or 4 randomly. Each index should have equal probability of returning.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>target</code> is an integer from <code>nums</code>.</li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>pick</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Reservoir Sampling](../../tag/reservoir-sampling/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Similar Questions
-  1. [Linked List Random Node](../linked-list-random-node) (Medium)
-  1. [Random Pick with Blacklist](../random-pick-with-blacklist) (Hard)
-  1. [Random Pick with Weight](../random-pick-with-weight) (Medium)
diff --git a/problems/random-pick-index/random_pick_index.go b/problems/random-pick-index/random_pick_index.go
deleted file mode 100644
index 09b6a62fb..000000000
--- a/problems/random-pick-index/random_pick_index.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem398
diff --git a/problems/random-pick-index/random_pick_index_test.go b/problems/random-pick-index/random_pick_index_test.go
deleted file mode 100644
index 09b6a62fb..000000000
--- a/problems/random-pick-index/random_pick_index_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem398
diff --git a/problems/random-pick-with-blacklist/README.md b/problems/random-pick-with-blacklist/README.md
deleted file mode 100644
index 3764338a9..000000000
--- a/problems/random-pick-with-blacklist/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../to-lower-case "To Lower Case")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-distinct-islands-ii "Number of Distinct Islands II")
-
-## [710. Random Pick with Blacklist (Hard)](https://leetcode.com/problems/random-pick-with-blacklist "黑名单中的随机数")
-
-<p>You are given an integer <code>n</code> and an array of unique integers <code>blacklist</code>. Design an algorithm to pick a random integer in the range <code>[0, n - 1]</code> that is not in <code>blacklist</code>. Any integer that is in the mentioned range and not in <code>blacklist</code> should be equally likely returned.</p>
-
-<p>Optimize your algorithm such that it minimizes the call to the <strong>built-in</strong> random function of your language.</p>
-
-<p>Implement the <code>Solution</code> class:</p>
-
-<ul>
-	<li><code>Solution(int n, int[] blacklist)</code> Initializes the object with the integer <code>n</code> and the blacklisted integers <code>blacklist</code>.</li>
-	<li><code>int pick()</code> Returns a random integer in the range <code>[0, n - 1]</code> and not in <code>blacklist</code>. All the possible integers should be equally likely returned.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Solution&quot;, &quot;pick&quot;, &quot;pick&quot;, &quot;pick&quot;, &quot;pick&quot;, &quot;pick&quot;, &quot;pick&quot;, &quot;pick&quot;]
-[[7, [2, 3, 5]], [], [], [], [], [], [], []]
-<strong>Output</strong>
-[null, 6, 4, 1, 6, 1, 6, 4]
-
-<strong>Explanation</strong>
-Solution solution = new Solution(7, [2, 3, 5]);
-solution.pick(); // return 6, any integer from [1,4,6] should be ok. Note that for every call of pick, 1, 4, and 6 must be equally likely to be returned (i.e., with probability 1/3).
-solution.pick(); // return 4
-solution.pick(); // return 1
-solution.pick(); // return 6
-solution.pick(); // return 1
-solution.pick(); // return 6
-solution.pick(); // return 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= blacklist.length &lt;- min(10<sup>5</sup>, n - 1)</code></li>
-	<li><code>0 &lt;= blacklist[i] &lt; n</code></li>
-	<li>All the values of <code>blacklist</code> are <strong>unique</strong>.</li>
-	<li>At most <code>2 * 10<sup>4</sup></code> calls will be made to <code>pick</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Similar Questions
-  1. [Random Pick Index](../random-pick-index) (Medium)
-  1. [Random Pick with Weight](../random-pick-with-weight) (Medium)
diff --git a/problems/random-pick-with-blacklist/random_pick_with_blacklist.go b/problems/random-pick-with-blacklist/random_pick_with_blacklist.go
deleted file mode 100644
index d6b081bfd..000000000
--- a/problems/random-pick-with-blacklist/random_pick_with_blacklist.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem710
diff --git a/problems/random-pick-with-blacklist/random_pick_with_blacklist_test.go b/problems/random-pick-with-blacklist/random_pick_with_blacklist_test.go
deleted file mode 100644
index d6b081bfd..000000000
--- a/problems/random-pick-with-blacklist/random_pick_with_blacklist_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem710
diff --git a/problems/random-pick-with-weight/README.md b/problems/random-pick-with-weight/README.md
deleted file mode 100644
index 003bbd478..000000000
--- a/problems/random-pick-with-weight/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-abbreviation "Word Abbreviation")
-　　　　　　　　　　　　　　　　
-[Next >](../minesweeper "Minesweeper")
-
-## [528. Random Pick with Weight (Medium)](https://leetcode.com/problems/random-pick-with-weight "按权重随机选择")
-
-<p>You are given a <strong>0-indexed</strong> array of positive integers <code>w</code> where <code>w[i]</code> describes the <strong>weight</strong> of the <code>i<sup>th</sup></code> index.</p>
-
-<p>You need to implement the function <code>pickIndex()</code>, which <strong>randomly</strong> picks an index in the range <code>[0, w.length - 1]</code> (<strong>inclusive</strong>) and returns it. The <strong>probability</strong> of picking an index <code>i</code> is <code>w[i] / sum(w)</code>.</p>
-
-<ul>
-	<li>For example, if <code>w = [1, 3]</code>, the probability of picking index <code>0</code> is <code>1 / (1 + 3) = 0.25</code> (i.e., <code>25%</code>), and the probability of picking index <code>1</code> is <code>3 / (1 + 3) = 0.75</code> (i.e., <code>75%</code>).</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Solution&quot;,&quot;pickIndex&quot;]
-[[[1]],[]]
-<strong>Output</strong>
-[null,0]
-
-<strong>Explanation</strong>
-Solution solution = new Solution([1]);
-solution.pickIndex(); // return 0. The only option is to return 0 since there is only one element in w.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Solution&quot;,&quot;pickIndex&quot;,&quot;pickIndex&quot;,&quot;pickIndex&quot;,&quot;pickIndex&quot;,&quot;pickIndex&quot;]
-[[[1,3]],[],[],[],[],[]]
-<strong>Output</strong>
-[null,1,1,1,1,0]
-
-<strong>Explanation</strong>
-Solution solution = new Solution([1, 3]);
-solution.pickIndex(); // return 1. It is returning the second element (index = 1) that has a probability of 3/4.
-solution.pickIndex(); // return 1
-solution.pickIndex(); // return 1
-solution.pickIndex(); // return 1
-solution.pickIndex(); // return 0. It is returning the first element (index = 0) that has a probability of 1/4.
-
-Since this is a randomization problem, multiple answers are allowed.
-All of the following outputs can be considered correct:
-[null,1,1,1,1,0]
-[null,1,1,1,1,1]
-[null,1,1,1,0,0]
-[null,1,1,1,0,1]
-[null,1,0,1,0,0]
-......
-and so on.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= w.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= w[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>pickIndex</code> will be called at most <code>10<sup>4</sup></code> times.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Similar Questions
-  1. [Random Pick Index](../random-pick-index) (Medium)
-  1. [Random Pick with Blacklist](../random-pick-with-blacklist) (Hard)
-  1. [Random Point in Non-overlapping Rectangles](../random-point-in-non-overlapping-rectangles) (Medium)
diff --git a/problems/random-pick-with-weight/random_pick_with_weight.go b/problems/random-pick-with-weight/random_pick_with_weight.go
deleted file mode 100644
index b648b1f17..000000000
--- a/problems/random-pick-with-weight/random_pick_with_weight.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem528
diff --git a/problems/random-pick-with-weight/random_pick_with_weight_test.go b/problems/random-pick-with-weight/random_pick_with_weight_test.go
deleted file mode 100644
index b648b1f17..000000000
--- a/problems/random-pick-with-weight/random_pick_with_weight_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem528
diff --git a/problems/random-point-in-non-overlapping-rectangles/README.md b/problems/random-point-in-non-overlapping-rectangles/README.md
deleted file mode 100644
index 3e58d9e56..000000000
--- a/problems/random-point-in-non-overlapping-rectangles/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../next-greater-element-i "Next Greater Element I")
-　　　　　　　　　　　　　　　　
-[Next >](../diagonal-traverse "Diagonal Traverse")
-
-## [497. Random Point in Non-overlapping Rectangles (Medium)](https://leetcode.com/problems/random-point-in-non-overlapping-rectangles "非重叠矩形中的随机点")
-
-<p>You are given an array of non-overlapping axis-aligned rectangles <code>rects</code> where <code>rects[i] = [a<sub>i</sub>, b<sub>i</sub>, x<sub>i</sub>, y<sub>i</sub>]</code> indicates that <code>(a<sub>i</sub>, b<sub>i</sub>)</code> is the bottom-left corner point of the <code>i<sup>th</sup></code> rectangle and <code>(x<sub>i</sub>, y<sub>i</sub>)</code> is the top-right corner point of the <code>i<sup>th</sup></code> rectangle. Design an algorithm to pick a random integer point inside the space covered by one of the given rectangles. A point on the perimeter of a rectangle is included in the space covered by the rectangle.</p>
-
-<p>Any integer point inside the space covered by one of the given rectangles should be equally likely to be returned.</p>
-
-<p><strong>Note</strong> that an integer point is a point that has integer coordinates.</p>
-
-<p>Implement the <code>Solution</code> class:</p>
-
-<ul>
-	<li><code>Solution(int[][] rects)</code> Initializes the object with the given rectangles <code>rects</code>.</li>
-	<li><code>int[] pick()</code> Returns a random integer point <code>[u, v]</code> inside the space covered by one of the given rectangles.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/24/lc-pickrandomrec.jpg" style="width: 419px; height: 539px;" />
-<pre>
-<strong>Input</strong>
-[&quot;Solution&quot;, &quot;pick&quot;, &quot;pick&quot;, &quot;pick&quot;, &quot;pick&quot;, &quot;pick&quot;]
-[[[[-2, -2, 1, 1], [2, 2, 4, 6]]], [], [], [], [], []]
-<strong>Output</strong>
-[null, [1, -2], [1, -1], [-1, -2], [-2, -2], [0, 0]]
-
-<strong>Explanation</strong>
-Solution solution = new Solution([[-2, -2, 1, 1], [2, 2, 4, 6]]);
-solution.pick(); // return [1, -2]
-solution.pick(); // return [1, -1]
-solution.pick(); // return [-1, -2]
-solution.pick(); // return [-2, -2]
-solution.pick(); // return [0, 0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rects.length &lt;= 100</code></li>
-	<li><code>rects[i].length == 4</code></li>
-	<li><code>-10<sup>9</sup> &lt;= a<sub>i</sub> &lt; x<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= b<sub>i</sub> &lt; y<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>x<sub>i</sub> - a<sub>i</sub> &lt;= 2000</code></li>
-	<li><code>y<sub>i</sub> - b<sub>i</sub> &lt;= 2000</code></li>
-	<li>All the rectangles do not overlap.</li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>pick</code>.</li>
-</ul>
-
-### Related Topics
-  [[Reservoir Sampling](../../tag/reservoir-sampling/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Similar Questions
-  1. [Random Pick with Weight](../random-pick-with-weight) (Medium)
-  1. [Generate Random Point in a Circle](../generate-random-point-in-a-circle) (Medium)
diff --git a/problems/random-point-in-non-overlapping-rectangles/random_point_in_non_overlapping_rectangles.go b/problems/random-point-in-non-overlapping-rectangles/random_point_in_non_overlapping_rectangles.go
deleted file mode 100644
index 11aff1db6..000000000
--- a/problems/random-point-in-non-overlapping-rectangles/random_point_in_non_overlapping_rectangles.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem497
diff --git a/problems/random-point-in-non-overlapping-rectangles/random_point_in_non_overlapping_rectangles_test.go b/problems/random-point-in-non-overlapping-rectangles/random_point_in_non_overlapping_rectangles_test.go
deleted file mode 100644
index 11aff1db6..000000000
--- a/problems/random-point-in-non-overlapping-rectangles/random_point_in_non_overlapping_rectangles_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem497
diff --git a/problems/range-addition-ii/README.md b/problems/range-addition-ii/README.md
deleted file mode 100644
index 8ed1babe6..000000000
--- a/problems/range-addition-ii/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../friend-requests-i-overall-acceptance-rate "Friend Requests I: Overall Acceptance Rate")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-index-sum-of-two-lists "Minimum Index Sum of Two Lists")
-
-## [598. Range Addition II (Easy)](https://leetcode.com/problems/range-addition-ii "范围求和 II")
-
-<p>You are given an <code>m x n</code> matrix <code>M</code> initialized with all <code>0</code>&#39;s and an array of operations <code>ops</code>, where <code>ops[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> means <code>M[x][y]</code> should be incremented by one for all <code>0 &lt;= x &lt; a<sub>i</sub></code> and <code>0 &lt;= y &lt; b<sub>i</sub></code>.</p>
-
-<p>Count and return <em>the number of maximum integers in the matrix after performing all the operations</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/02/ex1.jpg" style="width: 750px; height: 176px;" />
-<pre>
-<strong>Input:</strong> m = 3, n = 3, ops = [[2,2],[3,3]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The maximum integer in M is 2, and there are four of it in M. So return 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> m = 3, n = 3, ops = [[2,2],[3,3],[3,3],[3,3],[2,2],[3,3],[3,3],[3,3],[2,2],[3,3],[3,3],[3,3]]
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> m = 3, n = 3, ops = []
-<strong>Output:</strong> 9
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m, n &lt;= 4 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= ops.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>ops[i].length == 2</code></li>
-	<li><code>1 &lt;= a<sub>i</sub> &lt;= m</code></li>
-	<li><code>1 &lt;= b<sub>i</sub> &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Range Addition](../range-addition) (Medium)
diff --git a/problems/range-addition-ii/range_addition_ii.go b/problems/range-addition-ii/range_addition_ii.go
deleted file mode 100644
index 6e802a816..000000000
--- a/problems/range-addition-ii/range_addition_ii.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem598
-
-func maxCount(m int, n int, ops [][]int) int {
-	for _, op := range ops {
-		if m > op[0] {
-			m = op[0]
-		}
-		if n > op[1] {
-			n = op[1]
-		}
-	}
-	return m * n
-}
diff --git a/problems/range-addition-ii/range_addition_ii_test.go b/problems/range-addition-ii/range_addition_ii_test.go
deleted file mode 100644
index aff2a2d6e..000000000
--- a/problems/range-addition-ii/range_addition_ii_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem598
-
-import "testing"
-
-type testType struct {
-	m    int
-	n    int
-	ops  [][]int
-	want int
-}
-
-func TestMaxCount(t *testing.T) {
-	tests := [...]testType{
-		{
-			m: 3,
-			n: 3,
-			ops: [][]int{
-				{2, 2},
-				{3, 3},
-			},
-			want: 4,
-		},
-	}
-	for _, tt := range tests {
-		got := maxCount(tt.m, tt.n, tt.ops)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.m, got, tt.want)
-		}
-	}
-}
diff --git a/problems/range-addition/README.md b/problems/range-addition/README.md
deleted file mode 100644
index 595b65b0a..000000000
--- a/problems/range-addition/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../plus-one-linked-list "Plus One Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-two-integers "Sum of Two Integers")
-
-## [370. Range Addition (Medium)](https://leetcode.com/problems/range-addition "区间加法")
-
-<p>Assume you have an array of length <b><i>n</i></b> initialized with all <b>0</b>&#39;s and are given <b><i>k</i></b> update operations.</p>
-
-<p>Each operation is represented as a triplet: <b>[startIndex, endIndex, inc]</b> which increments each element of subarray <b>A[startIndex ... endIndex]</b> (startIndex and endIndex inclusive) with <b>inc</b>.</p>
-
-<p>Return the modified array after all <b><i>k</i></b> operations were executed.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input: </strong>length = <span id="example-input-1-1">5</span>, updates = <span id="example-input-1-2">[[1,3,2],[2,4,3],[0,2,-2]]</span>
-<strong>Output: </strong><span id="example-output-1">[-2,0,3,5,3]</span>
-</pre>
-
-<p><b>Explanation:</b></p>
-
-<pre>
-Initial state:
-[0,0,0,0,0]
-
-After applying operation [1,3,2]:
-[0,2,2,2,0]
-
-After applying operation [2,4,3]:
-[0,2,5,5,3]
-
-After applying operation [0,2,-2]:
-[-2,0,3,5,3]
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Range Addition II](../range-addition-ii) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Thinking of using advanced data structures? You are thinking it too complicated.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each update operation, do you really need to update all elements between i and j?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Update only the first and end element is sufficient.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The optimal time complexity is O(<b><i>k</i></b> + <b><i>n</i></b>) and uses O(1) extra space.
-</details>
diff --git a/problems/range-addition/range_addition.go b/problems/range-addition/range_addition.go
deleted file mode 100644
index a9f16c943..000000000
--- a/problems/range-addition/range_addition.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem370
diff --git a/problems/range-addition/range_addition_test.go b/problems/range-addition/range_addition_test.go
deleted file mode 100644
index a9f16c943..000000000
--- a/problems/range-addition/range_addition_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem370
diff --git a/problems/range-frequency-queries/README.md b/problems/range-frequency-queries/README.md
deleted file mode 100644
index 01668228f..000000000
--- a/problems/range-frequency-queries/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../watering-plants "Watering Plants")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-k-mirror-numbers "Sum of k-Mirror Numbers")
-
-## [2080. Range Frequency Queries (Medium)](https://leetcode.com/problems/range-frequency-queries "区间内查询数字的频率")
-
-<p>Design a data structure to find the <strong>frequency</strong> of a given value in a given subarray.</p>
-
-<p>The <strong>frequency</strong> of a value in a subarray is the number of occurrences of that value in the subarray.</p>
-
-<p>Implement the <code>RangeFreqQuery</code> class:</p>
-
-<ul>
-	<li><code>RangeFreqQuery(int[] arr)</code> Constructs an instance of the class with the given <strong>0-indexed</strong> integer array <code>arr</code>.</li>
-	<li><code>int query(int left, int right, int value)</code> Returns the <strong>frequency</strong> of <code>value</code> in the subarray <code>arr[left...right]</code>.</li>
-</ul>
-
-<p>A <strong>subarray</strong> is a contiguous sequence of elements within an array. <code>arr[left...right]</code> denotes the subarray that contains the elements of <code>nums</code> between indices <code>left</code> and <code>right</code> (<strong>inclusive</strong>).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;RangeFreqQuery&quot;, &quot;query&quot;, &quot;query&quot;]
-[[[12, 33, 4, 56, 22, 2, 34, 33, 22, 12, 34, 56]], [1, 2, 4], [0, 11, 33]]
-<strong>Output</strong>
-[null, 1, 2]
-
-<strong>Explanation</strong>
-RangeFreqQuery rangeFreqQuery = new RangeFreqQuery([12, 33, 4, 56, 22, 2, 34, 33, 22, 12, 34, 56]);
-rangeFreqQuery.query(1, 2, 4); // return 1. The value 4 occurs 1 time in the subarray [33, 4]
-rangeFreqQuery.query(0, 11, 33); // return 2. The value 33 occurs 2 times in the whole array.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= arr[i], value &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= left &lt;= right &lt; arr.length</code></li>
-	<li>At most <code>10<sup>5</sup></code> calls will be made to <code>query</code></li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The queries must be answered efficiently to avoid time limit exceeded verdict.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Store the elements of the array in a data structure that helps answering the queries efficiently.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use a hash table that stored for each value, the indices where that value appeared.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use binary search over the indices of a value to find its range frequency.
-</details>
diff --git a/problems/range-module/README.md b/problems/range-module/README.md
deleted file mode 100644
index f4f13ff58..000000000
--- a/problems/range-module/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-time-to-buy-and-sell-stock-with-transaction-fee "Best Time to Buy and Sell Stock with Transaction Fee")
-　　　　　　　　　　　　　　　　
-[Next >](../max-stack "Max Stack")
-
-## [715. Range Module (Hard)](https://leetcode.com/problems/range-module "Range 模块")
-
-<p>A Range Module is a module that tracks ranges of numbers. Design a data structure to track the ranges represented as <strong>half-open intervals</strong> and query about them.</p>
-
-<p>A <strong>half-open interval</strong> <code>[left, right)</code> denotes all the real numbers <code>x</code> where <code>left &lt;= x &lt; right</code>.</p>
-
-<p>Implement the <code>RangeModule</code> class:</p>
-
-<ul>
-	<li><code>RangeModule()</code> Initializes the object of the data structure.</li>
-	<li><code>void addRange(int left, int right)</code> Adds the <strong>half-open interval</strong> <code>[left, right)</code>, tracking every real number in that interval. Adding an interval that partially overlaps with currently tracked numbers should add any numbers in the interval <code>[left, right)</code> that are not already tracked.</li>
-	<li><code>boolean queryRange(int left, int right)</code> Returns <code>true</code> if every real number in the interval <code>[left, right)</code> is currently being tracked, and <code>false</code> otherwise.</li>
-	<li><code>void removeRange(int left, int right)</code> Stops tracking every real number currently being tracked in the <strong>half-open interval</strong> <code>[left, right)</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;RangeModule&quot;, &quot;addRange&quot;, &quot;removeRange&quot;, &quot;queryRange&quot;, &quot;queryRange&quot;, &quot;queryRange&quot;]
-[[], [10, 20], [14, 16], [10, 14], [13, 15], [16, 17]]
-<strong>Output</strong>
-[null, null, null, true, false, true]
-
-<strong>Explanation</strong>
-RangeModule rangeModule = new RangeModule();
-rangeModule.addRange(10, 20);
-rangeModule.removeRange(14, 16);
-rangeModule.queryRange(10, 14); // return True,(Every number in [10, 14) is being tracked)
-rangeModule.queryRange(13, 15); // return False,(Numbers like 14, 14.03, 14.17 in [13, 15) are not being tracked)
-rangeModule.queryRange(16, 17); // return True, (The number 16 in [16, 17) is still being tracked, despite the remove operation)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= left &lt; right &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>addRange</code>, <code>queryRange</code>, and <code>removeRange</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [Merge Intervals](../merge-intervals) (Medium)
-  1. [Insert Interval](../insert-interval) (Medium)
-  1. [Data Stream as Disjoint Intervals](../data-stream-as-disjoint-intervals) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Maintain a sorted set of disjoint intervals.  addRange and removeRange can be performed with time complexity linear to the size of this set; queryRange can be performed with time complexity logarithmic to the size of this set.
-</details>
diff --git a/problems/range-module/range_module.go b/problems/range-module/range_module.go
deleted file mode 100644
index 2261a5f8a..000000000
--- a/problems/range-module/range_module.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem715
diff --git a/problems/range-module/range_module_test.go b/problems/range-module/range_module_test.go
deleted file mode 100644
index 2261a5f8a..000000000
--- a/problems/range-module/range_module_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem715
diff --git a/problems/range-sum-of-bst/README.md b/problems/range-sum-of-bst/README.md
deleted file mode 100644
index db95e3008..000000000
--- a/problems/range-sum-of-bst/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reorder-data-in-log-files "Reorder Data in Log Files")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-area-rectangle "Minimum Area Rectangle")
-
-## [938. Range Sum of BST (Easy)](https://leetcode.com/problems/range-sum-of-bst "二叉搜索树的范围和")
-
-<p>Given the <code>root</code> node of a binary search tree and two integers <code>low</code> and <code>high</code>, return <em>the sum of values of all nodes with a value in the <strong>inclusive</strong> range </em><code>[low, high]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/bst1.jpg" style="width: 400px; height: 222px;" />
-<pre>
-<strong>Input:</strong> root = [10,5,15,3,7,null,18], low = 7, high = 15
-<strong>Output:</strong> 32
-<strong>Explanation:</strong> Nodes 7, 10, and 15 are in the range [7, 15]. 7 + 10 + 15 = 32.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/bst2.jpg" style="width: 400px; height: 335px;" />
-<pre>
-<strong>Input:</strong> root = [10,5,15,3,7,13,18,1,null,6], low = 6, high = 10
-<strong>Output:</strong> 23
-<strong>Explanation:</strong> Nodes 6, 7, and 10 are in the range [6, 10]. 6 + 7 + 10 = 23.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 2 * 10<sup>4</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= low &lt;= high &lt;= 10<sup>5</sup></code></li>
-	<li>All <code>Node.val</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/range-sum-of-bst/range_sum_of_bst.go b/problems/range-sum-of-bst/range_sum_of_bst.go
deleted file mode 100644
index 61d87593d..000000000
--- a/problems/range-sum-of-bst/range_sum_of_bst.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package problem938
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func rangeSumBST(root *TreeNode, L int, R int) int {
-	ans := 0
-	if root.Val >= L && root.Val <= R {
-		ans += root.Val
-	}
-	if root.Left != nil && root.Val > L {
-		ans += rangeSumBST(root.Left, L, R)
-	}
-	if root.Right != nil && root.Val < R {
-		ans += rangeSumBST(root.Right, L, R)
-	}
-	return ans
-}
diff --git a/problems/range-sum-of-bst/range_sum_of_bst_test.go b/problems/range-sum-of-bst/range_sum_of_bst_test.go
deleted file mode 100644
index 86b8e1020..000000000
--- a/problems/range-sum-of-bst/range_sum_of_bst_test.go
+++ /dev/null
@@ -1,37 +0,0 @@
-package problem938
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	l    int
-	r    int
-	want int
-}
-
-func TestRangeSumBST(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{10, 5, 15, 3, 7, kit.NULL, 18},
-			l:    7,
-			r:    15,
-			want: 32,
-		},
-		{
-			in:   []int{10, 5, 15, 3, 7, 13, 18, 1, kit.NULL, 6},
-			l:    6,
-			r:    10,
-			want: 23,
-		},
-	}
-	for _, tt := range tests {
-		got := rangeSumBST(kit.SliceInt2TreeNode(tt.in), tt.l, tt.r)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/range-sum-of-sorted-subarray-sums/README.md b/problems/range-sum-of-sorted-subarray-sums/README.md
deleted file mode 100644
index 6cc505677..000000000
--- a/problems/range-sum-of-sorted-subarray-sums/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reformat-date "Reformat Date")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-difference-between-largest-and-smallest-value-in-three-moves "Minimum Difference Between Largest and Smallest Value in Three Moves")
-
-## [1508. Range Sum of Sorted Subarray Sums (Medium)](https://leetcode.com/problems/range-sum-of-sorted-subarray-sums "子数组和排序后的区间和")
-
-<p>You are given the array <code>nums</code> consisting of <code>n</code> positive integers. You computed the sum of all non-empty continuous subarrays from the array and then sorted them in non-decreasing order, creating a new array of <code>n * (n + 1) / 2</code> numbers.</p>
-
-<p><em>Return the sum of the numbers from index </em><code>left</code><em> to index </em><code>right</code> (<strong>indexed from 1</strong>)<em>, inclusive, in the new array. </em>Since the answer can be a huge number return it modulo <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4], n = 4, left = 1, right = 5
-<strong>Output:</strong> 13 
-<strong>Explanation:</strong> All subarray sums are 1, 3, 6, 10, 2, 5, 9, 3, 7, 4. After sorting them in non-decreasing order we have the new array [1, 2, 3, 3, 4, 5, 6, 7, 9, 10]. The sum of the numbers from index le = 1 to ri = 5 is 1 + 2 + 3 + 3 + 4 = 13. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4], n = 4, left = 3, right = 4
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The given array is the same as example 1. We have the new array [1, 2, 3, 3, 4, 5, 6, 7, 9, 10]. The sum of the numbers from index le = 3 to ri = 4 is 3 + 3 = 6.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4], n = 4, left = 1, right = 10
-<strong>Output:</strong> 50
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-	<li><code>1 &lt;= left &lt;= right &lt;= n * (n + 1) / 2</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Compute all sums and save it in array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Then just go from LEFT to RIGHT index and calculate answer modulo 1e9 + 7.
-</details>
diff --git a/problems/range-sum-query-2d-immutable/README.md b/problems/range-sum-query-2d-immutable/README.md
deleted file mode 100644
index 9b87031fe..000000000
--- a/problems/range-sum-query-2d-immutable/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-sum-query-immutable "Range Sum Query - Immutable")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-islands-ii "Number of Islands II")
-
-## [304. Range Sum Query 2D - Immutable (Medium)](https://leetcode.com/problems/range-sum-query-2d-immutable "二维区域和检索 - 矩阵不可变")
-
-<p>Given a 2D matrix <code>matrix</code>, handle multiple queries of the following type:</p>
-
-<ul>
-	<li>Calculate the <strong>sum</strong> of the elements of <code>matrix</code> inside the rectangle defined by its <strong>upper left corner</strong> <code>(row1, col1)</code> and <strong>lower right corner</strong> <code>(row2, col2)</code>.</li>
-</ul>
-
-<p>Implement the NumMatrix class:</p>
-
-<ul>
-	<li><code>NumMatrix(int[][] matrix)</code> Initializes the object with the integer matrix <code>matrix</code>.</li>
-	<li><code>int sumRegion(int row1, int col1, int row2, int col2)</code> Returns the <strong>sum</strong> of the elements of <code>matrix</code> inside the rectangle defined by its <strong>upper left corner</strong> <code>(row1, col1)</code> and <strong>lower right corner</strong> <code>(row2, col2)</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/14/sum-grid.jpg" style="width: 415px; height: 415px;" />
-<pre>
-<strong>Input</strong>
-[&quot;NumMatrix&quot;, &quot;sumRegion&quot;, &quot;sumRegion&quot;, &quot;sumRegion&quot;]
-[[[[3, 0, 1, 4, 2], [5, 6, 3, 2, 1], [1, 2, 0, 1, 5], [4, 1, 0, 1, 7], [1, 0, 3, 0, 5]]], [2, 1, 4, 3], [1, 1, 2, 2], [1, 2, 2, 4]]
-<strong>Output</strong>
-[null, 8, 11, 12]
-
-<strong>Explanation</strong>
-NumMatrix numMatrix = new NumMatrix([[3, 0, 1, 4, 2], [5, 6, 3, 2, 1], [1, 2, 0, 1, 5], [4, 1, 0, 1, 7], [1, 0, 3, 0, 5]]);
-numMatrix.sumRegion(2, 1, 4, 3); // return 8 (i.e sum of the red rectangle)
-numMatrix.sumRegion(1, 1, 2, 2); // return 11 (i.e sum of the green rectangle)
-numMatrix.sumRegion(1, 2, 2, 4); // return 12 (i.e sum of the blue rectangle)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>-10<sup>5</sup> &lt;= matrix[i][j] &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= row1 &lt;= row2 &lt; m</code></li>
-	<li><code>0 &lt;= col1 &lt;= col2 &lt; n</code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>sumRegion</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Range Sum Query - Immutable](../range-sum-query-immutable) (Easy)
-  1. [Range Sum Query 2D - Mutable](../range-sum-query-2d-mutable) (Hard)
diff --git a/problems/range-sum-query-2d-immutable/range_sum_query_2d_immutable.go b/problems/range-sum-query-2d-immutable/range_sum_query_2d_immutable.go
deleted file mode 100644
index 0025cde1f..000000000
--- a/problems/range-sum-query-2d-immutable/range_sum_query_2d_immutable.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem304
diff --git a/problems/range-sum-query-2d-immutable/range_sum_query_2d_immutable_test.go b/problems/range-sum-query-2d-immutable/range_sum_query_2d_immutable_test.go
deleted file mode 100644
index 0025cde1f..000000000
--- a/problems/range-sum-query-2d-immutable/range_sum_query_2d_immutable_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem304
diff --git a/problems/range-sum-query-2d-mutable/README.md b/problems/range-sum-query-2d-mutable/README.md
deleted file mode 100644
index 652e5d210..000000000
--- a/problems/range-sum-query-2d-mutable/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-sum-query-mutable "Range Sum Query - Mutable")
-　　　　　　　　　　　　　　　　
-[Next >](../best-time-to-buy-and-sell-stock-with-cooldown "Best Time to Buy and Sell Stock with Cooldown")
-
-## [308. Range Sum Query 2D - Mutable (Hard)](https://leetcode.com/problems/range-sum-query-2d-mutable "二维区域和检索 - 可变")
-
-<p>Given a 2D matrix <i>matrix</i>, find the sum of the elements inside the rectangle defined by its upper left corner (<i>row</i>1, <i>col</i>1) and lower right corner (<i>row</i>2, <i>col</i>2).</p>
-
-<p>
-<img src="https://assets.leetcode.com/static_assets/public/images/courses/range_sum_query_2d.png" border="0" alt="Range Sum Query 2D" /><br />
-<small>The above rectangle (with the red border) is defined by (row1, col1) = <b>(2, 1)</b> and (row2, col2) = <b>(4, 3)</b>, which contains sum = <b>8</b>.</small>
-</p>
-
-<p><b>Example:</b><br>
-<pre>
-Given matrix = [
-  [3, 0, 1, 4, 2],
-  [5, 6, 3, 2, 1],
-  [1, 2, 0, 1, 5],
-  [4, 1, 0, 1, 7],
-  [1, 0, 3, 0, 5]
-]
-
-sumRegion(2, 1, 4, 3) -> 8
-update(3, 2, 2)
-sumRegion(2, 1, 4, 3) -> 10
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>The matrix is only modifiable by the <i>update</i> function.</li>
-<li>You may assume the number of calls to <i>update</i> and <i>sumRegion</i> function is distributed evenly.</li>
-<li>You may assume that <i>row</i>1 &le; <i>row</i>2 and <i>col</i>1 &le; <i>col</i>2.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Range Sum Query 2D - Immutable](../range-sum-query-2d-immutable) (Medium)
-  1. [Range Sum Query - Mutable](../range-sum-query-mutable) (Medium)
diff --git a/problems/range-sum-query-2d-mutable/range_sum_query_2d_mutable.go b/problems/range-sum-query-2d-mutable/range_sum_query_2d_mutable.go
deleted file mode 100644
index 8c4e842c5..000000000
--- a/problems/range-sum-query-2d-mutable/range_sum_query_2d_mutable.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem308
diff --git a/problems/range-sum-query-2d-mutable/range_sum_query_2d_mutable_test.go b/problems/range-sum-query-2d-mutable/range_sum_query_2d_mutable_test.go
deleted file mode 100644
index 8c4e842c5..000000000
--- a/problems/range-sum-query-2d-mutable/range_sum_query_2d_mutable_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem308
diff --git a/problems/range-sum-query-immutable/README.md b/problems/range-sum-query-immutable/README.md
deleted file mode 100644
index 450493ab6..000000000
--- a/problems/range-sum-query-immutable/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-rectangle-enclosing-black-pixels "Smallest Rectangle Enclosing Black Pixels")
-　　　　　　　　　　　　　　　　
-[Next >](../range-sum-query-2d-immutable "Range Sum Query 2D - Immutable")
-
-## [303. Range Sum Query - Immutable (Easy)](https://leetcode.com/problems/range-sum-query-immutable "区域和检索 - 数组不可变")
-
-<p>Given an integer array <code>nums</code>, handle multiple queries of the following type:</p>
-
-<ol>
-	<li>Calculate the <strong>sum</strong> of the elements of <code>nums</code> between indices <code>left</code> and <code>right</code> <strong>inclusive</strong> where <code>left &lt;= right</code>.</li>
-</ol>
-
-<p>Implement the <code>NumArray</code> class:</p>
-
-<ul>
-	<li><code>NumArray(int[] nums)</code> Initializes the object with the integer array <code>nums</code>.</li>
-	<li><code>int sumRange(int left, int right)</code> Returns the <strong>sum</strong> of the elements of <code>nums</code> between indices <code>left</code> and <code>right</code> <strong>inclusive</strong> (i.e. <code>nums[left] + nums[left + 1] + ... + nums[right]</code>).</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;NumArray&quot;, &quot;sumRange&quot;, &quot;sumRange&quot;, &quot;sumRange&quot;]
-[[[-2, 0, 3, -5, 2, -1]], [0, 2], [2, 5], [0, 5]]
-<strong>Output</strong>
-[null, 1, -1, -3]
-
-<strong>Explanation</strong>
-NumArray numArray = new NumArray([-2, 0, 3, -5, 2, -1]);
-numArray.sumRange(0, 2); // return (-2) + 0 + 3 = 1
-numArray.sumRange(2, 5); // return 3 + (-5) + 2 + (-1) = -1
-numArray.sumRange(0, 5); // return (-2) + 0 + 3 + (-5) + 2 + (-1) = -3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= left &lt;= right &lt; nums.length</code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>sumRange</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Range Sum Query 2D - Immutable](../range-sum-query-2d-immutable) (Medium)
-  1. [Range Sum Query - Mutable](../range-sum-query-mutable) (Medium)
-  1. [Maximum Size Subarray Sum Equals k](../maximum-size-subarray-sum-equals-k) (Medium)
diff --git a/problems/range-sum-query-immutable/range_sum_query_immutable.go b/problems/range-sum-query-immutable/range_sum_query_immutable.go
deleted file mode 100644
index 9b050adcc..000000000
--- a/problems/range-sum-query-immutable/range_sum_query_immutable.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem303
-
-type NumArray struct {
-	sum []int
-}
-
-func Constructor(nums []int) NumArray {
-	sum, na := 0, NumArray{make([]int, len(nums)+1)}
-	na.sum[0] = 0
-	for i, v := range nums {
-		sum += v
-		na.sum[i+1] = sum
-	}
-	return na
-}
-
-func (this *NumArray) SumRange(i int, j int) int {
-	return this.sum[j+1] - this.sum[i]
-}
-
-/**
- * Your NumArray object will be instantiated and called as such:
- * obj := Constructor(nums);
- * param_1 := obj.SumRange(i,j);
- */
diff --git a/problems/range-sum-query-immutable/range_sum_query_immutable_test.go b/problems/range-sum-query-immutable/range_sum_query_immutable_test.go
deleted file mode 100644
index 57c2a2e37..000000000
--- a/problems/range-sum-query-immutable/range_sum_query_immutable_test.go
+++ /dev/null
@@ -1,37 +0,0 @@
-package problem303
-
-import "testing"
-
-type testType struct {
-	i    int
-	j    int
-	want int
-}
-
-func TestConstructor(t *testing.T) {
-	nums := []int{-2, 0, 3, -5, 2, -1}
-	obj := Constructor(nums)
-	tests := [...]testType{
-		{
-			i:    0,
-			j:    2,
-			want: 1,
-		},
-		{
-			i:    2,
-			j:    5,
-			want: -1,
-		},
-		{
-			i:    0,
-			j:    5,
-			want: -3,
-		},
-	}
-	for _, tt := range tests {
-		got := obj.SumRange(tt.i, tt.j)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.i, tt.j, got, tt.want)
-		}
-	}
-}
diff --git a/problems/range-sum-query-mutable/README.md b/problems/range-sum-query-mutable/README.md
deleted file mode 100644
index 9e9b4991a..000000000
--- a/problems/range-sum-query-mutable/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../additive-number "Additive Number")
-　　　　　　　　　　　　　　　　
-[Next >](../range-sum-query-2d-mutable "Range Sum Query 2D - Mutable")
-
-## [307. Range Sum Query - Mutable (Medium)](https://leetcode.com/problems/range-sum-query-mutable "区域和检索 - 数组可修改")
-
-<p>Given an integer array <code>nums</code>, handle multiple queries of the following types:</p>
-
-<ol>
-	<li><strong>Update</strong> the value of an element in <code>nums</code>.</li>
-	<li>Calculate the <strong>sum</strong> of the elements of <code>nums</code> between indices <code>left</code> and <code>right</code> <strong>inclusive</strong> where <code>left &lt;= right</code>.</li>
-</ol>
-
-<p>Implement the <code>NumArray</code> class:</p>
-
-<ul>
-	<li><code>NumArray(int[] nums)</code> Initializes the object with the integer array <code>nums</code>.</li>
-	<li><code>void update(int index, int val)</code> <strong>Updates</strong> the value of <code>nums[index]</code> to be <code>val</code>.</li>
-	<li><code>int sumRange(int left, int right)</code> Returns the <strong>sum</strong> of the elements of <code>nums</code> between indices <code>left</code> and <code>right</code> <strong>inclusive</strong> (i.e. <code>nums[left] + nums[left + 1] + ... + nums[right]</code>).</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;NumArray&quot;, &quot;sumRange&quot;, &quot;update&quot;, &quot;sumRange&quot;]
-[[[1, 3, 5]], [0, 2], [1, 2], [0, 2]]
-<strong>Output</strong>
-[null, 9, null, 8]
-
-<strong>Explanation</strong>
-NumArray numArray = new NumArray([1, 3, 5]);
-numArray.sumRange(0, 2); // return 1 + 3 + 5 = 9
-numArray.update(1, 2);   // nums = [1, 2, 5]
-numArray.sumRange(0, 2); // return 1 + 2 + 5 = 8
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
-	<li><code>0 &lt;= index &lt; nums.length</code></li>
-	<li><code>-100 &lt;= val &lt;= 100</code></li>
-	<li><code>0 &lt;= left &lt;= right &lt; nums.length</code></li>
-	<li>At most <code>3 * 10<sup>4</sup></code> calls will be made to <code>update</code> and <code>sumRange</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-
-### Similar Questions
-  1. [Range Sum Query - Immutable](../range-sum-query-immutable) (Easy)
-  1. [Range Sum Query 2D - Mutable](../range-sum-query-2d-mutable) (Hard)
diff --git a/problems/range-sum-query-mutable/range_sum_query_mutable.go b/problems/range-sum-query-mutable/range_sum_query_mutable.go
deleted file mode 100644
index 9722f8a2c..000000000
--- a/problems/range-sum-query-mutable/range_sum_query_mutable.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem307
diff --git a/problems/range-sum-query-mutable/range_sum_query_mutable_test.go b/problems/range-sum-query-mutable/range_sum_query_mutable_test.go
deleted file mode 100644
index 9722f8a2c..000000000
--- a/problems/range-sum-query-mutable/range_sum_query_mutable_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem307
diff --git a/problems/rank-scores/README.md b/problems/rank-scores/README.md
deleted file mode 100644
index 22dc4120c..000000000
--- a/problems/rank-scores/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../nth-highest-salary "Nth Highest Salary")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-number "Largest Number")
-
-## [178. Rank Scores (Medium)](https://leetcode.com/problems/rank-scores "分数排名")
-
-<p>Table: <code>Scores</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| id          | int     |
-| score       | decimal |
-+-------------+---------+
-id is the primary key for this table.
-Each row of this table contains the score of a game. Score is a floating point value with two decimal places.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to rank the scores. The ranking should be calculated according to the following rules:</p>
-
-<ul>
-	<li>The scores should be ranked from the highest to the lowest.</li>
-	<li>If there is a tie between two scores, both should have the same ranking.</li>
-	<li>After a tie, the next ranking number should be the next consecutive integer value. In other words, there should be no holes between ranks.</li>
-</ul>
-
-<p>Return the result table ordered by <code>score</code> in descending order.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Scores table:
-+----+-------+
-| id | score |
-+----+-------+
-| 1  | 3.50  |
-| 2  | 3.65  |
-| 3  | 4.00  |
-| 4  | 3.85  |
-| 5  | 4.00  |
-| 6  | 3.65  |
-+----+-------+
-<strong>Output:</strong> 
-+-------+------+
-| score | rank |
-+-------+------+
-| 4.00  | 1    |
-| 4.00  | 1    |
-| 3.85  | 2    |
-| 3.65  | 3    |
-| 3.65  | 3    |
-| 3.50  | 4    |
-+-------+------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/rank-scores/mysql_schemas.sql b/problems/rank-scores/mysql_schemas.sql
deleted file mode 100644
index e95d6ffae..000000000
--- a/problems/rank-scores/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Scores (id int, score DECIMAL(3,2));
-Truncate table Scores;
-insert into Scores (id, score) values ('1', '3.5');
-insert into Scores (id, score) values ('2', '3.65');
-insert into Scores (id, score) values ('3', '4.0');
-insert into Scores (id, score) values ('4', '3.85');
-insert into Scores (id, score) values ('5', '4.0');
-insert into Scores (id, score) values ('6', '3.65');
diff --git a/problems/rank-scores/rank_scores.sql b/problems/rank-scores/rank_scores.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/rank-scores/rank_scores.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/rank-teams-by-votes/README.md b/problems/rank-teams-by-votes/README.md
deleted file mode 100644
index 5c2dc2e62..000000000
--- a/problems/rank-teams-by-votes/README.md
+++ /dev/null
@@ -1,101 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../how-many-numbers-are-smaller-than-the-current-number "How Many Numbers Are Smaller Than the Current Number")
-　　　　　　　　　　　　　　　　
-[Next >](../linked-list-in-binary-tree "Linked List in Binary Tree")
-
-## [1366. Rank Teams by Votes (Medium)](https://leetcode.com/problems/rank-teams-by-votes "通过投票对团队排名")
-
-<p>In a special ranking system,&nbsp;each voter gives a rank from highest to lowest to all teams participated in the competition.</p>
-
-<p>The ordering of teams is decided by who received the most position-one votes. If two or more teams tie in the first position, we consider the second position to resolve the conflict, if they tie again, we continue this process until the ties are resolved. If two or more teams are still tied after considering all positions, we rank them alphabetically based on their team letter.</p>
-
-<p>Given an array of strings <code>votes</code> which is the votes of all voters in the ranking systems. Sort all teams according to the ranking system described above.</p>
-
-<p>Return <em>a string of all teams</em> <strong>sorted</strong> by the ranking system.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> votes = [&quot;ABC&quot;,&quot;ACB&quot;,&quot;ABC&quot;,&quot;ACB&quot;,&quot;ACB&quot;]
-<strong>Output:</strong> &quot;ACB&quot;
-<strong>Explanation:</strong> Team A was ranked first place by 5 voters. No other team was voted as first place so team A is the first team.
-Team B was ranked second by 2 voters and was ranked third by 3 voters.
-Team C was ranked second by 3 voters and was ranked third by 2 voters.
-As most of the voters ranked C second, team C is the second team and team B is the third.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> votes = [&quot;WXYZ&quot;,&quot;XYZW&quot;]
-<strong>Output:</strong> &quot;XWYZ&quot;
-<strong>Explanation:</strong> X is the winner due to tie-breaking rule. X has same votes as W for the first position but X has one vote as second position while W doesn&#39;t have any votes as second position. 
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> votes = [&quot;ZMNAGUEDSJYLBOPHRQICWFXTVK&quot;]
-<strong>Output:</strong> &quot;ZMNAGUEDSJYLBOPHRQICWFXTVK&quot;
-<strong>Explanation:</strong> Only one voter so his votes are used for the ranking.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> votes = [&quot;BCA&quot;,&quot;CAB&quot;,&quot;CBA&quot;,&quot;ABC&quot;,&quot;ACB&quot;,&quot;BAC&quot;]
-<strong>Output:</strong> &quot;ABC&quot;
-<strong>Explanation:</strong> 
-Team A was ranked first by 2 voters, second by 2 voters and third by 2 voters.
-Team B was ranked first by 2 voters, second by 2 voters and third by 2 voters.
-Team C was ranked first by 2 voters, second by 2 voters and third by 2 voters.
-There is a tie and we rank teams ascending by their IDs.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> votes = [&quot;M&quot;,&quot;M&quot;,&quot;M&quot;,&quot;M&quot;]
-<strong>Output:</strong> &quot;M&quot;
-<strong>Explanation:</strong> Only team M in the competition so it has the first rank.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= votes.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= votes[i].length &lt;= 26</code></li>
-	<li><code>votes[i].length ==&nbsp;votes[j].length</code> for&nbsp;<code>0 &lt;= i, j &lt; votes.length</code>.</li>
-	<li><code>votes[i][j]</code> is an English <strong>upper-case</strong> letter.</li>
-	<li>All characters of <code>votes[i]</code> are unique.</li>
-	<li>All the characters&nbsp;that occur&nbsp;in <code>votes[0]</code> <strong>also&nbsp;occur</strong>&nbsp;in <code>votes[j]</code> where <code>1 &lt;= j &lt; votes.length</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Online Election](../online-election) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build array rank where rank[i][j] is the number of votes for team i to be the j-th rank.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort the trams by rank array. if rank array is the same for two or more teams, sort them by the ID in ascending order.
-</details>
diff --git a/problems/rank-transform-of-a-matrix/README.md b/problems/rank-transform-of-a-matrix/README.md
deleted file mode 100644
index 50ab56c4c..000000000
--- a/problems/rank-transform-of-a-matrix/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../path-with-minimum-effort "Path With Minimum Effort")
-　　　　　　　　　　　　　　　　
-[Next >](../percentage-of-users-attended-a-contest "Percentage of Users Attended a Contest")
-
-## [1632. Rank Transform of a Matrix (Hard)](https://leetcode.com/problems/rank-transform-of-a-matrix "矩阵转换后的秩")
-
-<p>Given an <code>m x n</code> <code>matrix</code>, return <em>a new matrix </em><code>answer</code><em> where </em><code>answer[row][col]</code><em> is the </em><em><strong>rank</strong> of </em><code>matrix[row][col]</code>.</p>
-
-<p>The <strong>rank</strong> is an <strong>integer</strong> that represents how large an element is compared to other elements. It is calculated using the following rules:</p>
-
-<ul>
-	<li>The rank is an integer starting from <code>1</code>.</li>
-	<li>If two elements <code>p</code> and <code>q</code> are in the <strong>same row or column</strong>, then:
-	<ul>
-		<li>If <code>p &lt; q</code> then <code>rank(p) &lt; rank(q)</code></li>
-		<li>If <code>p == q</code> then <code>rank(p) == rank(q)</code></li>
-		<li>If <code>p &gt; q</code> then <code>rank(p) &gt; rank(q)</code></li>
-	</ul>
-	</li>
-	<li>The <strong>rank</strong> should be as <strong>small</strong> as possible.</li>
-</ul>
-
-<p>The test cases are generated so that <code>answer</code> is unique under the given rules.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/18/rank1.jpg" style="width: 442px; height: 162px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,2],[3,4]]
-<strong>Output:</strong> [[1,2],[2,3]]
-<strong>Explanation:</strong>
-The rank of matrix[0][0] is 1 because it is the smallest integer in its row and column.
-The rank of matrix[0][1] is 2 because matrix[0][1] &gt; matrix[0][0] and matrix[0][0] is rank 1.
-The rank of matrix[1][0] is 2 because matrix[1][0] &gt; matrix[0][0] and matrix[0][0] is rank 1.
-The rank of matrix[1][1] is 3 because matrix[1][1] &gt; matrix[0][1], matrix[1][1] &gt; matrix[1][0], and both matrix[0][1] and matrix[1][0] are rank 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/18/rank2.jpg" style="width: 442px; height: 162px;" />
-<pre>
-<strong>Input:</strong> matrix = [[7,7],[7,7]]
-<strong>Output:</strong> [[1,1],[1,1]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/18/rank3.jpg" style="width: 601px; height: 322px;" />
-<pre>
-<strong>Input:</strong> matrix = [[20,-21,14],[-19,4,19],[22,-47,24],[-19,4,19]]
-<strong>Output:</strong> [[4,2,3],[1,3,4],[5,1,6],[1,3,4]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 500</code></li>
-	<li><code>-10<sup>9</sup> &lt;= matrix[row][col] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the cells by value and process them in increasing order.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The rank of a cell is the maximum rank in its row and column plus one.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Handle the equal cells by treating them as components using a union-find data structure.
-</details>
diff --git a/problems/rank-transform-of-an-array/README.md b/problems/rank-transform-of-an-array/README.md
deleted file mode 100644
index acf600fb2..000000000
--- a/problems/rank-transform-of-an-array/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-subarray-to-maximize-array-value "Reverse Subarray To Maximize Array Value")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-palindromic-subsequences "Remove Palindromic Subsequences")
-
-## [1331. Rank Transform of an Array (Easy)](https://leetcode.com/problems/rank-transform-of-an-array "数组序号转换")
-
-<p>Given an array of integers&nbsp;<code>arr</code>, replace each element with its rank.</p>
-
-<p>The rank represents how large the element is. The rank has the following rules:</p>
-
-<ul>
-	<li>Rank is an integer starting from 1.</li>
-	<li>The larger the element, the larger the rank. If two elements are equal, their rank must be the same.</li>
-	<li>Rank should be as small as possible.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [40,10,20,30]
-<strong>Output:</strong> [4,1,2,3]
-<strong>Explanation</strong>: 40 is the largest element. 10 is the smallest. 20 is the second smallest. 30 is the third smallest.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [100,100,100]
-<strong>Output:</strong> [1,1,1]
-<strong>Explanation</strong>: Same elements share the same rank.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [37,12,28,9,100,56,80,5,12]
-<strong>Output:</strong> [5,3,4,2,8,6,7,1,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup>&nbsp;&lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a temporary array to copy the array and sort it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The rank of each element is the number of elements smaller than it in the sorted array plus one.
-</details>
diff --git a/problems/ransom-note/README.md b/problems/ransom-note/README.md
deleted file mode 100644
index f917eded4..000000000
--- a/problems/ransom-note/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../linked-list-random-node "Linked List Random Node")
-　　　　　　　　　　　　　　　　
-[Next >](../shuffle-an-array "Shuffle an Array")
-
-## [383. Ransom Note (Easy)](https://leetcode.com/problems/ransom-note "赎金信")
-
-<p>Given two stings <code>ransomNote</code> and <code>magazine</code>, return <code>true</code> if <code>ransomNote</code> can be constructed from <code>magazine</code> and <code>false</code> otherwise.</p>
-
-<p>Each letter in <code>magazine</code> can only be used once in <code>ransomNote</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> ransomNote = "a", magazine = "b"
-<strong>Output:</strong> false
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> ransomNote = "aa", magazine = "ab"
-<strong>Output:</strong> false
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> ransomNote = "aa", magazine = "aab"
-<strong>Output:</strong> true
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= ransomNote.length, magazine.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>ransomNote</code> and <code>magazine</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Stickers to Spell Word](../stickers-to-spell-word) (Hard)
diff --git a/problems/ransom-note/ransom_note.go b/problems/ransom-note/ransom_note.go
deleted file mode 100644
index 823741374..000000000
--- a/problems/ransom-note/ransom_note.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem383
-
-func canConstruct(ransomNote string, magazine string) bool {
-	var m [128]int
-	for _, c := range magazine {
-		m[c]++
-	}
-	for _, c := range ransomNote {
-		m[c]--
-		if m[c] < 0 {
-			return false
-		}
-	}
-	return true
-}
diff --git a/problems/ransom-note/ransom_note_test.go b/problems/ransom-note/ransom_note_test.go
deleted file mode 100644
index 32ead09ec..000000000
--- a/problems/ransom-note/ransom_note_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem383
-
-import "testing"
-
-type testType struct {
-	ransom   string
-	magazine string
-	want     bool
-}
-
-func TestCanConstruct(t *testing.T) {
-	tests := [...]testType{
-		{
-			ransom:   "a",
-			magazine: "b",
-			want:     false,
-		},
-		{
-			ransom:   "aa",
-			magazine: "ab",
-			want:     false,
-		},
-		{
-			ransom:   "aa",
-			magazine: "aab",
-			want:     true,
-		},
-	}
-	for _, tt := range tests {
-		got := canConstruct(tt.ransom, tt.magazine)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.ransom, tt.magazine, got, tt.want)
-		}
-	}
-}
diff --git a/problems/reach-a-number/README.md b/problems/reach-a-number/README.md
deleted file mode 100644
index 3d3d442ee..000000000
--- a/problems/reach-a-number/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cracking-the-safe "Cracking the Safe")
-　　　　　　　　　　　　　　　　
-[Next >](../pour-water "Pour Water")
-
-## [754. Reach a Number (Medium)](https://leetcode.com/problems/reach-a-number "到达终点数字")
-
-<p>You are standing at position <code>0</code> on an infinite number line. There is a destination at position <code>target</code>.</p>
-
-<p>You can make some number of moves <code>numMoves</code> so that:</p>
-
-<ul>
-	<li>On each move, you can either go left or right.</li>
-	<li>During the <code>i<sup>th</sup></code> move (starting from <code>i == 1</code> to <code>i == numMoves</code>), you take <code>i</code> steps in the chosen direction.</li>
-</ul>
-
-<p>Given the integer <code>target</code>, return <em>the <strong>minimum</strong> number of moves required (i.e., the minimum </em><code>numMoves</code><em>) to reach the destination</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 2
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-On the 1<sup>st</sup> move, we step from 0 to 1 (1 step).
-On the 2<sup>nd</sup> move, we step from 1 to -1 (2 steps).
-On the 3<sup>rd</sup> move, we step from -1 to 2 (3 steps).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> target = 3
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-On the 1<sup>st</sup> move, we step from 0 to 1 (1 step).
-On the 2<sup>nd</sup> move, we step from 1 to 3 (2 steps).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-10<sup>9</sup> &lt;= target &lt;= 10<sup>9</sup></code></li>
-	<li><code>target != 0</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
diff --git a/problems/reach-a-number/reach_a_number.go b/problems/reach-a-number/reach_a_number.go
deleted file mode 100644
index 3c0a54e16..000000000
--- a/problems/reach-a-number/reach_a_number.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem754
diff --git a/problems/reach-a-number/reach_a_number_test.go b/problems/reach-a-number/reach_a_number_test.go
deleted file mode 100644
index 3c0a54e16..000000000
--- a/problems/reach-a-number/reach_a_number_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem754
diff --git a/problems/reachable-nodes-in-subdivided-graph/README.md b/problems/reachable-nodes-in-subdivided-graph/README.md
deleted file mode 100644
index a47afe276..000000000
--- a/problems/reachable-nodes-in-subdivided-graph/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../boats-to-save-people "Boats to Save People")
-　　　　　　　　　　　　　　　　
-[Next >](../projection-area-of-3d-shapes "Projection Area of 3D Shapes")
-
-## [882. Reachable Nodes In Subdivided Graph (Hard)](https://leetcode.com/problems/reachable-nodes-in-subdivided-graph "细分图中的可到达结点")
-
-<p>You are given an undirected graph (the <strong>&quot;original graph&quot;</strong>) with <code>n</code> nodes labeled from <code>0</code> to <code>n - 1</code>. You decide to <strong>subdivide</strong> each edge in the graph into a chain of nodes, with the number of new nodes varying between each edge.</p>
-
-<p>The graph is given as a 2D array of <code>edges</code> where <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>, cnt<sub>i</sub>]</code> indicates that there is an edge between nodes <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code> in the original graph, and <code>cnt<sub>i</sub></code> is the total number of new nodes that you will <strong>subdivide</strong> the edge into. Note that <code>cnt<sub>i</sub> == 0</code> means you will not subdivide the edge.</p>
-
-<p>To <strong>subdivide</strong> the edge <code>[u<sub>i</sub>, v<sub>i</sub>]</code>, replace it with <code>(cnt<sub>i</sub> + 1)</code> new edges and <code>cnt<sub>i</sub></code> new nodes. The new nodes are <code>x<sub>1</sub></code>, <code>x<sub>2</sub></code>, ..., <code>x<sub>cnt<sub>i</sub></sub></code>, and the new edges are <code>[u<sub>i</sub>, x<sub>1</sub>]</code>, <code>[x<sub>1</sub>, x<sub>2</sub>]</code>, <code>[x<sub>2</sub>, x<sub>3</sub>]</code>, ..., <code>[x<sub>cnt<sub>i</sub>+1</sub>, x<sub>cnt<sub>i</sub></sub>]</code>, <code>[x<sub>cnt<sub>i</sub></sub>, v<sub>i</sub>]</code>.</p>
-
-<p>In this <strong>new graph</strong>, you want to know how many nodes are <strong>reachable</strong> from the node <code>0</code>, where a node is <strong>reachable</strong> if the distance is <code>maxMoves</code> or less.</p>
-
-<p>Given the original graph and <code>maxMoves</code>, return <em>the number of nodes that are <strong>reachable</strong> from node </em><code>0</code><em> in the new graph</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/08/01/origfinal.png" style="width: 600px; height: 247px;" />
-<pre>
-<strong>Input:</strong> edges = [[0,1,10],[0,2,1],[1,2,2]], maxMoves = 6, n = 3
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> The edge subdivisions are shown in the image above.
-The nodes that are reachable are highlighted in yellow.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> edges = [[0,1,4],[1,2,6],[0,2,8],[1,3,1]], maxMoves = 10, n = 4
-<strong>Output:</strong> 23
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> edges = [[1,2,4],[1,4,5],[1,3,1],[2,3,4],[3,4,5]], maxMoves = 17, n = 5
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Node 0 is disconnected from the rest of the graph, so only node 0 is reachable.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= edges.length &lt;= min(n * (n - 1) / 2, 10<sup>4</sup>)</code></li>
-	<li><code>edges[i].length == 3</code></li>
-	<li><code>0 &lt;= u<sub>i</sub> &lt; v<sub>i</sub> &lt; n</code></li>
-	<li>There are <strong>no multiple edges</strong> in the graph.</li>
-	<li><code>0 &lt;= cnt<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= maxMoves &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= n &lt;= 3000</code></li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
diff --git a/problems/reachable-nodes-in-subdivided-graph/reachable_nodes_in_subdivided_graph.go b/problems/reachable-nodes-in-subdivided-graph/reachable_nodes_in_subdivided_graph.go
deleted file mode 100644
index 56e3829da..000000000
--- a/problems/reachable-nodes-in-subdivided-graph/reachable_nodes_in_subdivided_graph.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem882
diff --git a/problems/reachable-nodes-in-subdivided-graph/reachable_nodes_in_subdivided_graph_test.go b/problems/reachable-nodes-in-subdivided-graph/reachable_nodes_in_subdivided_graph_test.go
deleted file mode 100644
index 56e3829da..000000000
--- a/problems/reachable-nodes-in-subdivided-graph/reachable_nodes_in_subdivided_graph_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem882
diff --git a/problems/reaching-points/README.md b/problems/reaching-points/README.md
deleted file mode 100644
index 4ee9f7625..000000000
--- a/problems/reaching-points/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-th-symbol-in-grammar "K-th Symbol in Grammar")
-　　　　　　　　　　　　　　　　
-[Next >](../rabbits-in-forest "Rabbits in Forest")
-
-## [780. Reaching Points (Hard)](https://leetcode.com/problems/reaching-points "到达终点")
-
-<p>Given four integers <code>sx</code>, <code>sy</code>, <code>tx</code>, and <code>ty</code>, return <code>true</code><em> if it is possible to convert the point </em><code>(sx, sy)</code><em> to the point </em><code>(tx, ty)</code> <em>through some operations</em><em>, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>The allowed operation on some point <code>(x, y)</code> is to convert it to either <code>(x, x + y)</code> or <code>(x + y, y)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> sx = 1, sy = 1, tx = 3, ty = 5
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-One series of moves that transforms the starting point to the target is:
-(1, 1) -&gt; (1, 2)
-(1, 2) -&gt; (3, 2)
-(3, 2) -&gt; (3, 5)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> sx = 1, sy = 1, tx = 2, ty = 2
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> sx = 1, sy = 1, tx = 1, ty = 1
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= sx, sy, tx, ty &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/reaching-points/reaching_points.go b/problems/reaching-points/reaching_points.go
deleted file mode 100644
index fd7529475..000000000
--- a/problems/reaching-points/reaching_points.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem780
diff --git a/problems/reaching-points/reaching_points_test.go b/problems/reaching-points/reaching_points_test.go
deleted file mode 100644
index fd7529475..000000000
--- a/problems/reaching-points/reaching_points_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem780
diff --git a/problems/read-n-characters-given-read4-ii-call-multiple-times/README.md b/problems/read-n-characters-given-read4-ii-call-multiple-times/README.md
deleted file mode 100644
index 4ceaafb65..000000000
--- a/problems/read-n-characters-given-read4-ii-call-multiple-times/README.md
+++ /dev/null
@@ -1,102 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../read-n-characters-given-read4 "Read N Characters Given Read4")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-substring-with-at-most-two-distinct-characters "Longest Substring with At Most Two Distinct Characters")
-
-## [158. Read N Characters Given Read4 II - Call multiple times (Hard)](https://leetcode.com/problems/read-n-characters-given-read4-ii-call-multiple-times "用 Read4 读取 N 个字符 II")
-
-<p>Given a file and assume that you can only read the file using a given method&nbsp;<code>read4</code>, implement a method <code>read</code> to read <em>n</em> characters. <strong>Your method <code>read</code> may be called multiple times.</strong></p>
-
-<p>&nbsp;</p>
-
-<p><b>Method read4: </b></p>
-
-<p>The API&nbsp;<code>read4</code> reads 4 consecutive characters from the file, then writes those characters into the buffer array <code>buf</code>.</p>
-
-<p>The return value is the number of actual characters read.</p>
-
-<p>Note that&nbsp;<code>read4()</code> has its own file pointer, much like <code>FILE *fp</code> in C.</p>
-
-<p><b>Definition of read4:</b></p>
-
-<pre>
-    Parameter:  char[] buf
-    Returns:    int
-
-Note: buf[] is destination not source, the results from read4 will be copied to buf[]
-</pre>
-
-<p>Below is a high level example of how <code>read4</code> works:</p>
-
-<pre>
-<code>File file(&quot;abcdefghijk&quot;); // File is &quot;abcdefghijk&quot;, initially file pointer (fp) points to &#39;a&#39;
-char[] buf = new char[4]; // Create buffer with enough space to store characters
-read4(buf); // read4 returns 4. Now buf = &quot;abcd&quot;, fp points to &#39;e&#39;
-read4(buf); // read4 returns 4. Now buf = &quot;efgh&quot;, fp points to &#39;i&#39;
-read4(buf); // read4 returns 3. Now buf = &quot;ijk&quot;, fp points to end of file</code>
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Method read:</strong></p>
-
-<p>By using the <code>read4</code> method, implement the method&nbsp;<code>read</code> that reads <i>n</i> characters from the file and store it in the&nbsp;buffer array&nbsp;<code>buf</code>. Consider that you <strong>cannot</strong> manipulate the file directly.</p>
-
-<p>The return value is the number of actual characters read.</p>
-
-<p><b>Definition of read: </b></p>
-
-<pre>
-    Parameters:	char[] buf, int n
-    Returns:	int
-
-Note: buf[] is destination not source, you will need to write the results to buf[]
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-File file(&quot;abc&quot;);
-Solution sol;
-// Assume buf is allocated and guaranteed to have enough space for storing all characters from the file.
-sol.read(buf, 1); // After calling your read method, buf should contain &quot;a&quot;. We read a total of 1 character from the file, so return 1.
-sol.read(buf, 2); // Now buf should contain &quot;bc&quot;. We read a total of 2 characters from the file, so return 2.
-sol.read(buf, 1); // We have reached the end of file, no more characters can be read. So return 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-File file(&quot;abc&quot;);
-Solution sol;
-sol.read(buf, 4); // After calling your read method, buf should contain &quot;abc&quot;. We read a total of 3 characters from the file, so return 3.
-sol.read(buf, 1); // We have reached the end of file, no more characters can be read. So return 0.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>Consider that you <strong>cannot</strong> manipulate the file directly, the file is only accesible for <code>read4</code> but&nbsp;<strong>not</strong> for <code>read</code>.</li>
-	<li>The <code>read</code> function may be called <strong>multiple times</strong>.</li>
-	<li>Please remember to <b>RESET</b> your class variables declared in Solution, as static/class variables are <b>persisted across multiple test cases</b>. Please see <a href="https://leetcode.com/faq/" target="_blank">here</a> for more details.</li>
-	<li>You may assume the destination buffer array,&nbsp;<code>buf</code>,&nbsp;is guaranteed to have enough&nbsp;space for storing&nbsp;<em>n</em>&nbsp;characters.</li>
-	<li>It is guaranteed that in a given test case the same buffer <code>buf</code> is called by <code>read</code>.</li>
-</ol>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Read N Characters Given Read4](../read-n-characters-given-read4) (Easy)
diff --git a/problems/read-n-characters-given-read4-ii-call-multiple-times/read_n_characters_given_read4_ii_call_multiple_times.go b/problems/read-n-characters-given-read4-ii-call-multiple-times/read_n_characters_given_read4_ii_call_multiple_times.go
deleted file mode 100644
index abd510725..000000000
--- a/problems/read-n-characters-given-read4-ii-call-multiple-times/read_n_characters_given_read4_ii_call_multiple_times.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem158
diff --git a/problems/read-n-characters-given-read4-ii-call-multiple-times/read_n_characters_given_read4_ii_call_multiple_times_test.go b/problems/read-n-characters-given-read4-ii-call-multiple-times/read_n_characters_given_read4_ii_call_multiple_times_test.go
deleted file mode 100644
index abd510725..000000000
--- a/problems/read-n-characters-given-read4-ii-call-multiple-times/read_n_characters_given_read4_ii_call_multiple_times_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem158
diff --git a/problems/read-n-characters-given-read4/README.md b/problems/read-n-characters-given-read4/README.md
deleted file mode 100644
index 9cb75e643..000000000
--- a/problems/read-n-characters-given-read4/README.md
+++ /dev/null
@@ -1,112 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-upside-down "Binary Tree Upside Down")
-　　　　　　　　　　　　　　　　
-[Next >](../read-n-characters-given-read4-ii-call-multiple-times "Read N Characters Given Read4 II - Call multiple times")
-
-## [157. Read N Characters Given Read4 (Easy)](https://leetcode.com/problems/read-n-characters-given-read4 "用 Read4 读取 N 个字符")
-
-<p>Given a file and assume that you can only read the file using a given method&nbsp;<code>read4</code>, implement a method to read <em>n</em> characters.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Method read4: </b></p>
-
-<p>The API&nbsp;<code>read4</code> reads 4 consecutive characters from the file, then writes those characters into the buffer array <code>buf</code>.</p>
-
-<p>The return value is the number of actual characters read.</p>
-
-<p>Note that&nbsp;<code>read4()</code> has its own file pointer, much like <code>FILE *fp</code> in C.</p>
-
-<p><b>Definition of read4:</b></p>
-
-<pre>
-    Parameter:  char[] buf
-    Returns:    int
-
-Note: buf[] is destination not source, the results from read4 will be copied to buf[]
-</pre>
-
-<p>Below is a high level example of how <code>read4</code> works:</p>
-
-<pre>
-<code>File file(&quot;abcdefghijk&quot;); // File is &quot;abcdefghijk&quot;, initially file pointer (fp) points to &#39;a&#39;
-char[] buf = new char[4]; // Create buffer with enough space to store characters
-read4(buf); // read4 returns 4. Now buf = &quot;abcd&quot;, fp points to &#39;e&#39;
-read4(buf); // read4 returns 4. Now buf = &quot;efgh&quot;, fp points to &#39;i&#39;
-read4(buf); // read4 returns 3. Now buf = &quot;ijk&quot;, fp points to end of file</code>
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Method read:</strong></p>
-
-<p>By using the <code>read4</code> method, implement the method&nbsp;<code>read</code> that reads <i>n</i> characters from the file and store it in the&nbsp;buffer array&nbsp;<code>buf</code>. Consider that you <strong>cannot</strong> manipulate the file directly.</p>
-
-<p>The return value is the number of actual characters read.</p>
-
-<p><b>Definition of read: </b></p>
-
-<pre>
-    Parameters:	char[] buf, int n
-    Returns:	int
-
-Note: buf[] is destination not source, you will need to write the results to buf[]
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>file = &quot;abc&quot;, n = 4
-<strong>Output: </strong>3
-<strong>Explanation:</strong>&nbsp;After calling your read method, buf should contain &quot;abc&quot;. We read a total of 3 characters from the file, so return 3. Note that &quot;abc&quot; is the file&#39;s content, not buf. buf is the destination buffer that you will have to write the results to.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>file = &quot;abcde&quot;, n = 5
-<strong>Output: </strong>5
-<strong>Explanation: </strong>After calling your read method, buf should contain &quot;abcde&quot;. We read a total of 5 characters from the file, so return 5.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong>file = &quot;abcdABCD1234&quot;, n = 12
-<strong>Output: </strong>12
-<strong>Explanation: </strong>After calling your read method, buf should contain &quot;abcdABCD1234&quot;. We read a total of 12 characters from the file, so return 12.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input: </strong>file = &quot;leetcode&quot;, n = 5
-<strong>Output: </strong>5
-<strong>Explanation: </strong>After calling your read method, buf should contain &quot;leetc&quot;. We read a total of 5 characters from the file, so return 5.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>Consider that you <strong>cannot</strong> manipulate the file directly, the file is only accesible for <code>read4</code> but&nbsp;<strong>not</strong> for <code>read</code>.</li>
-	<li>The <code>read</code> function will only be called once for each test case.</li>
-	<li>You may assume the destination buffer array,&nbsp;<code>buf</code>,&nbsp;is guaranteed to have enough&nbsp;space for storing&nbsp;<em>n</em>&nbsp;characters.</li>
-</ol>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Read N Characters Given Read4 II - Call multiple times](../read-n-characters-given-read4-ii-call-multiple-times) (Hard)
diff --git a/problems/read-n-characters-given-read4/read_n_characters_given_read4.go b/problems/read-n-characters-given-read4/read_n_characters_given_read4.go
deleted file mode 100644
index 0be8d1def..000000000
--- a/problems/read-n-characters-given-read4/read_n_characters_given_read4.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem157
diff --git a/problems/read-n-characters-given-read4/read_n_characters_given_read4_test.go b/problems/read-n-characters-given-read4/read_n_characters_given_read4_test.go
deleted file mode 100644
index 0be8d1def..000000000
--- a/problems/read-n-characters-given-read4/read_n_characters_given_read4_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem157
diff --git a/problems/rearrange-array-elements-by-sign/README.md b/problems/rearrange-array-elements-by-sign/README.md
deleted file mode 100644
index 42e6a72bd..000000000
--- a/problems/rearrange-array-elements-by-sign/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-elements-with-strictly-smaller-and-greater-elements "Count Elements With Strictly Smaller and Greater Elements ")
-　　　　　　　　　　　　　　　　
-[Next >](../find-all-lonely-numbers-in-the-array "Find All Lonely Numbers in the Array")
-
-## [2149. Rearrange Array Elements by Sign (Medium)](https://leetcode.com/problems/rearrange-array-elements-by-sign "按符号重排数组")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code> of <strong>even</strong> length consisting of an <strong>equal</strong> number of positive and negative integers.</p>
-
-<p>You should <strong>rearrange</strong> the elements of <code>nums</code> such that the modified array follows the given conditions:</p>
-
-<ol>
-	<li>Every <strong>consecutive pair</strong> of integers have <strong>opposite signs</strong>.</li>
-	<li>For all integers with the same sign, the <strong>order</strong> in which they were present in <code>nums</code> is <strong>preserved</strong>.</li>
-	<li>The rearranged array begins with a positive integer.</li>
-</ol>
-
-<p>Return <em>the modified array after rearranging the elements to satisfy the aforementioned conditions</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,-2,-5,2,-4]
-<strong>Output:</strong> [3,-2,1,-5,2,-4]
-<strong>Explanation:</strong>
-The positive integers in nums are [3,1,2]. The negative integers are [-2,-5,-4].
-The only possible way to rearrange them such that they satisfy all conditions is [3,-2,1,-5,2,-4].
-Other ways such as [1,-2,2,-5,3,-4], [3,1,2,-2,-5,-4], [-2,3,-5,1,-4,2] are incorrect because they do not satisfy one or more conditions.  
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,1]
-<strong>Output:</strong> [1,-1]
-<strong>Explanation:</strong>
-1 is the only positive integer and -1 the only negative integer in nums.
-So nums is rearranged to [1,-1].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>nums.length</code> is <strong>even</strong></li>
-	<li><code>1 &lt;= |nums[i]| &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums</code> consists of <strong>equal</strong> number of positive and negative integers.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Divide the array into two parts- one comprising of only positive integers and the other of negative integers.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Merge the two parts to get the resultant array.
-</details>
diff --git a/problems/rearrange-products-table/README.md b/problems/rearrange-products-table/README.md
deleted file mode 100644
index 834046e1b..000000000
--- a/problems/rearrange-products-table/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-pairs-of-equal-substrings-with-minimum-difference "Count Pairs of Equal Substrings With Minimum Difference")
-　　　　　　　　　　　　　　　　
-[Next >](../second-largest-digit-in-a-string "Second Largest Digit in a String")
-
-## [1795. Rearrange Products Table (Easy)](https://leetcode.com/problems/rearrange-products-table "每个产品在不同商店的价格")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/rearrange-products-table/mysql_schemas.sql b/problems/rearrange-products-table/mysql_schemas.sql
deleted file mode 100644
index 80706d663..000000000
--- a/problems/rearrange-products-table/mysql_schemas.sql
+++ /dev/null
@@ -1,4 +0,0 @@
-Create table If Not Exists Products (product_id int, store1 int, store2 int, store3 int);
-Truncate table Products;
-insert into Products (product_id, store1, store2, store3) values ('0', '95', '100', '105');
-insert into Products (product_id, store1, store2, store3) values ('1', '70', 'None', '80');
diff --git a/problems/rearrange-spaces-between-words/README.md b/problems/rearrange-spaces-between-words/README.md
deleted file mode 100644
index 96a5b97d5..000000000
--- a/problems/rearrange-spaces-between-words/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../strange-printer-ii "Strange Printer II")
-　　　　　　　　　　　　　　　　
-[Next >](../split-a-string-into-the-max-number-of-unique-substrings "Split a String Into the Max Number of Unique Substrings")
-
-## [1592. Rearrange Spaces Between Words (Easy)](https://leetcode.com/problems/rearrange-spaces-between-words "重新排列单词间的空格")
-
-<p>You are given a string <code>text</code> of words that are placed among some number of spaces. Each word consists of one or more lowercase English letters and are separated by at least one space. It&#39;s guaranteed that <code>text</code> <strong>contains at least one word</strong>.</p>
-
-<p>Rearrange the spaces so that there is an <strong>equal</strong> number of spaces between every pair of adjacent words and that number is <strong>maximized</strong>. If you cannot redistribute all the spaces equally, place the <strong>extra spaces at the end</strong>, meaning the returned string should be the same length as <code>text</code>.</p>
-
-<p>Return <em>the string after rearranging the spaces</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;  this   is  a sentence &quot;
-<strong>Output:</strong> &quot;this   is   a   sentence&quot;
-<strong>Explanation:</strong> There are a total of 9 spaces and 4 words. We can evenly divide the 9 spaces between the words: 9 / (4-1) = 3 spaces.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot; practice   makes   perfect&quot;
-<strong>Output:</strong> &quot;practice   makes   perfect &quot;
-<strong>Explanation:</strong> There are a total of 7 spaces and 3 words. 7 / (3-1) = 3 spaces plus 1 extra space. We place this extra space at the end of the string.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= text.length &lt;= 100</code></li>
-	<li><code>text</code> consists of lowercase English letters and <code>&#39; &#39;</code>.</li>
-	<li><code>text</code> contains at least one word.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Text Justification](../text-justification) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the total number of spaces and words. Then use the integer division to determine the numbers of spaces to add between each word and at the end.
-</details>
diff --git a/problems/rearrange-string-k-distance-apart/README.md b/problems/rearrange-string-k-distance-apart/README.md
deleted file mode 100644
index 831175238..000000000
--- a/problems/rearrange-string-k-distance-apart/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-numbers-with-unique-digits "Count Numbers with Unique Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../logger-rate-limiter "Logger Rate Limiter")
-
-## [358. Rearrange String k Distance Apart (Hard)](https://leetcode.com/problems/rearrange-string-k-distance-apart "K 距离间隔重排字符串")
-
-<p>Given a non-empty string <b>s</b> and an integer <b>k</b>, rearrange the string such that the same characters are at least distance <b>k</b> from each other.</p>
-
-<p>All input strings are given in lowercase letters. If it is not possible to rearrange the string, return an empty string <code>&quot;&quot;</code>.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<div>
-<pre>
-<strong>Input: </strong>s = <span id="example-input-1-1">&quot;aabbcc&quot;</span>, k = <span id="example-input-1-2">3</span>
-<strong>Output: </strong><span id="example-output-1">&quot;abcabc&quot; 
-<strong>Explanation: </strong></span>The same letters are at least distance 3 from each other.
-</pre>
-
-<div>
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>s = <span id="example-input-2-1">&quot;aaabc&quot;</span>, k = <span id="example-input-2-2">3</span>
-<strong>Output: </strong><span id="example-output-2">&quot;&quot; 
-<strong>Explanation:</strong> </span>It is not possible to rearrange the string.
-</pre>
-
-<div>
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong>s = <span id="example-input-3-1">&quot;aaadbbcc&quot;</span>, k = <span id="example-input-3-2">2</span>
-<strong>Output: </strong><span id="example-output-3">&quot;abacabcd&quot;
-</span><span id="example-output-2"><strong>Explanation:</strong> </span>The same letters are at least distance 2 from each other.
-</pre>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Task Scheduler](../task-scheduler) (Medium)
-  1. [Reorganize String](../reorganize-string) (Medium)
diff --git a/problems/rearrange-string-k-distance-apart/rearrange_string_k_distance_apart.go b/problems/rearrange-string-k-distance-apart/rearrange_string_k_distance_apart.go
deleted file mode 100644
index a8d67bc26..000000000
--- a/problems/rearrange-string-k-distance-apart/rearrange_string_k_distance_apart.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem358
diff --git a/problems/rearrange-string-k-distance-apart/rearrange_string_k_distance_apart_test.go b/problems/rearrange-string-k-distance-apart/rearrange_string_k_distance_apart_test.go
deleted file mode 100644
index a8d67bc26..000000000
--- a/problems/rearrange-string-k-distance-apart/rearrange_string_k_distance_apart_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem358
diff --git a/problems/rearrange-words-in-a-sentence/README.md b/problems/rearrange-words-in-a-sentence/README.md
deleted file mode 100644
index b920aad7d..000000000
--- a/problems/rearrange-words-in-a-sentence/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-students-doing-homework-at-a-given-time "Number of Students Doing Homework at a Given Time")
-　　　　　　　　　　　　　　　　
-[Next >](../people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list "People Whose List of Favorite Companies Is Not a Subset of Another List")
-
-## [1451. Rearrange Words in a Sentence (Medium)](https://leetcode.com/problems/rearrange-words-in-a-sentence "重新排列句子中的单词")
-
-<p>Given a sentence&nbsp;<code>text</code> (A&nbsp;<em>sentence</em>&nbsp;is a string of space-separated words) in the following format:</p>
-
-<ul>
-	<li>First letter is in upper case.</li>
-	<li>Each word in <code>text</code> are separated by a single space.</li>
-</ul>
-
-<p>Your task is to rearrange the words in text such that&nbsp;all words are rearranged in an increasing order of their lengths. If two words have the same length, arrange them in their original order.</p>
-
-<p>Return the new text&nbsp;following the format shown above.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;Leetcode is cool&quot;
-<strong>Output:</strong> &quot;Is cool leetcode&quot;
-<strong>Explanation: </strong>There are 3 words, &quot;Leetcode&quot; of length 8, &quot;is&quot; of length 2 and &quot;cool&quot; of length 4.
-Output is ordered by length and the new first word starts with capital letter.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;Keep calm and code on&quot;
-<strong>Output:</strong> &quot;On and keep calm code&quot;
-<strong>Explanation: </strong>Output is ordered as follows:
-&quot;On&quot; 2 letters.
-&quot;and&quot; 3 letters.
-&quot;keep&quot; 4 letters in case of tie order by position in original text.
-&quot;calm&quot; 4 letters.
-&quot;code&quot; 4 letters.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;To be or not to be&quot;
-<strong>Output:</strong> &quot;To be or to be not&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>text</code> begins with a capital letter and then contains lowercase letters and single space between words.</li>
-	<li><code>1 &lt;= text.length &lt;= 10^5</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Store each word and their relative position. Then, sort them by length of words in case of tie by their original order.
-</details>
diff --git a/problems/reconstruct-a-2-row-binary-matrix/README.md b/problems/reconstruct-a-2-row-binary-matrix/README.md
deleted file mode 100644
index 99fabdd1a..000000000
--- a/problems/reconstruct-a-2-row-binary-matrix/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cells-with-odd-values-in-a-matrix "Cells with Odd Values in a Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-closed-islands "Number of Closed Islands")
-
-## [1253. Reconstruct a 2-Row Binary Matrix (Medium)](https://leetcode.com/problems/reconstruct-a-2-row-binary-matrix "重构 2 行二进制矩阵")
-
-<p>Given the following details of a matrix with <code>n</code> columns and <code>2</code> rows :</p>
-
-<ul>
-	<li>The matrix is a binary matrix, which means each element in the matrix can be <code>0</code> or <code>1</code>.</li>
-	<li>The sum of elements of the 0-th(upper) row is given as <code>upper</code>.</li>
-	<li>The sum of elements of the 1-st(lower) row is given as <code>lower</code>.</li>
-	<li>The sum of elements in the i-th column(0-indexed) is <code>colsum[i]</code>, where <code>colsum</code> is given as an integer array with length <code>n</code>.</li>
-</ul>
-
-<p>Your task is to reconstruct the matrix with <code>upper</code>, <code>lower</code> and <code>colsum</code>.</p>
-
-<p>Return it as a 2-D integer array.</p>
-
-<p>If there are more than one valid solution, any of them will be accepted.</p>
-
-<p>If no valid solution exists, return an empty 2-D array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> upper = 2, lower = 1, colsum = [1,1,1]
-<strong>Output:</strong> [[1,1,0],[0,0,1]]
-<strong>Explanation: </strong>[[1,0,1],[0,1,0]], and [[0,1,1],[1,0,0]] are also correct answers.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> upper = 2, lower = 3, colsum = [2,2,1,1]
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> upper = 5, lower = 5, colsum = [2,1,2,0,1,0,1,2,0,1]
-<strong>Output:</strong> [[1,1,1,0,1,0,0,1,0,0],[1,0,1,0,0,0,1,1,0,1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= colsum.length &lt;= 10^5</code></li>
-	<li><code>0 &lt;= upper, lower &lt;= colsum.length</code></li>
-	<li><code>0 &lt;= colsum[i] &lt;= 2</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Find Valid Matrix Given Row and Column Sums](../find-valid-matrix-given-row-and-column-sums) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You cannot do anything about colsum[i] = 2 case or colsum[i] = 0 case. Then you put colsum[i] = 1 case to the upper row until upper has reached. Then put the rest into lower row.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Fill 0 and 2 first, then fill 1 in the upper row or lower row in turn but be careful about exhausting permitted 1s in each row.
-</details>
diff --git a/problems/reconstruct-itinerary/README.md b/problems/reconstruct-itinerary/README.md
deleted file mode 100644
index 02269425d..000000000
--- a/problems/reconstruct-itinerary/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../verify-preorder-serialization-of-a-binary-tree "Verify Preorder Serialization of a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-bst-subtree "Largest BST Subtree")
-
-## [332. Reconstruct Itinerary (Hard)](https://leetcode.com/problems/reconstruct-itinerary "重新安排行程")
-
-<p>You are given a list of airline <code>tickets</code> where <code>tickets[i] = [from<sub>i</sub>, to<sub>i</sub>]</code> represent the departure and the arrival airports of one flight. Reconstruct the itinerary in order and return it.</p>
-
-<p>All of the tickets belong to a man who departs from <code>&quot;JFK&quot;</code>, thus, the itinerary must begin with <code>&quot;JFK&quot;</code>. If there are multiple valid itineraries, you should return the itinerary that has the smallest lexical order when read as a single string.</p>
-
-<ul>
-	<li>For example, the itinerary <code>[&quot;JFK&quot;, &quot;LGA&quot;]</code> has a smaller lexical order than <code>[&quot;JFK&quot;, &quot;LGB&quot;]</code>.</li>
-</ul>
-
-<p>You may assume all tickets form at least one valid itinerary. You must use all the tickets once and only once.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/14/itinerary1-graph.jpg" style="width: 382px; height: 222px;" />
-<pre>
-<strong>Input:</strong> tickets = [[&quot;MUC&quot;,&quot;LHR&quot;],[&quot;JFK&quot;,&quot;MUC&quot;],[&quot;SFO&quot;,&quot;SJC&quot;],[&quot;LHR&quot;,&quot;SFO&quot;]]
-<strong>Output:</strong> [&quot;JFK&quot;,&quot;MUC&quot;,&quot;LHR&quot;,&quot;SFO&quot;,&quot;SJC&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/14/itinerary2-graph.jpg" style="width: 222px; height: 230px;" />
-<pre>
-<strong>Input:</strong> tickets = [[&quot;JFK&quot;,&quot;SFO&quot;],[&quot;JFK&quot;,&quot;ATL&quot;],[&quot;SFO&quot;,&quot;ATL&quot;],[&quot;ATL&quot;,&quot;JFK&quot;],[&quot;ATL&quot;,&quot;SFO&quot;]]
-<strong>Output:</strong> [&quot;JFK&quot;,&quot;ATL&quot;,&quot;JFK&quot;,&quot;SFO&quot;,&quot;ATL&quot;,&quot;SFO&quot;]
-<strong>Explanation:</strong> Another possible reconstruction is [&quot;JFK&quot;,&quot;SFO&quot;,&quot;ATL&quot;,&quot;JFK&quot;,&quot;ATL&quot;,&quot;SFO&quot;] but it is larger in lexical order.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= tickets.length &lt;= 300</code></li>
-	<li><code>tickets[i].length == 2</code></li>
-	<li><code>from<sub>i</sub>.length == 3</code></li>
-	<li><code>to<sub>i</sub>.length == 3</code></li>
-	<li><code>from<sub>i</sub></code> and <code>to<sub>i</sub></code> consist of uppercase English letters.</li>
-	<li><code>from<sub>i</sub> != to<sub>i</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Eulerian Circuit](../../tag/eulerian-circuit/README.md)]
-
-### Similar Questions
-  1. [Longest Common Subpath](../longest-common-subpath) (Hard)
diff --git a/problems/reconstruct-itinerary/reconstruct_itinerary.go b/problems/reconstruct-itinerary/reconstruct_itinerary.go
deleted file mode 100644
index fac4d61ba..000000000
--- a/problems/reconstruct-itinerary/reconstruct_itinerary.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem332
diff --git a/problems/reconstruct-itinerary/reconstruct_itinerary_test.go b/problems/reconstruct-itinerary/reconstruct_itinerary_test.go
deleted file mode 100644
index fac4d61ba..000000000
--- a/problems/reconstruct-itinerary/reconstruct_itinerary_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem332
diff --git a/problems/reconstruct-original-digits-from-english/README.md b/problems/reconstruct-original-digits-from-english/README.md
deleted file mode 100644
index b2233eee7..000000000
--- a/problems/reconstruct-original-digits-from-english/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-word-square "Valid Word Square")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-repeating-character-replacement "Longest Repeating Character Replacement")
-
-## [423. Reconstruct Original Digits from English (Medium)](https://leetcode.com/problems/reconstruct-original-digits-from-english "从英文中重建数字")
-
-<p>Given a string <code>s</code> containing an out-of-order English representation of digits <code>0-9</code>, return <em>the digits in <strong>ascending</strong> order</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "owoztneoer"
-<strong>Output:</strong> "012"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "fviefuro"
-<strong>Output:</strong> "45"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is one of the characters <code>[&quot;e&quot;,&quot;g&quot;,&quot;f&quot;,&quot;i&quot;,&quot;h&quot;,&quot;o&quot;,&quot;n&quot;,&quot;s&quot;,&quot;r&quot;,&quot;u&quot;,&quot;t&quot;,&quot;w&quot;,&quot;v&quot;,&quot;x&quot;,&quot;z&quot;]</code>.</li>
-	<li><code>s</code> is <strong>guaranteed</strong> to be valid.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/reconstruct-original-digits-from-english/reconstruct_original_digits_from_english.go b/problems/reconstruct-original-digits-from-english/reconstruct_original_digits_from_english.go
deleted file mode 100644
index d1642117b..000000000
--- a/problems/reconstruct-original-digits-from-english/reconstruct_original_digits_from_english.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem423
diff --git a/problems/reconstruct-original-digits-from-english/reconstruct_original_digits_from_english_test.go b/problems/reconstruct-original-digits-from-english/reconstruct_original_digits_from_english_test.go
deleted file mode 100644
index d1642117b..000000000
--- a/problems/reconstruct-original-digits-from-english/reconstruct_original_digits_from_english_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem423
diff --git a/problems/recover-a-tree-from-preorder-traversal/README.md b/problems/recover-a-tree-from-preorder-traversal/README.md
deleted file mode 100644
index 9c1a4fc92..000000000
--- a/problems/recover-a-tree-from-preorder-traversal/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-arithmetic-subsequence "Longest Arithmetic Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../two-city-scheduling "Two City Scheduling")
-
-## [1028. Recover a Tree From Preorder Traversal (Hard)](https://leetcode.com/problems/recover-a-tree-from-preorder-traversal "从先序遍历还原二叉树")
-
-<p>We run a&nbsp;preorder&nbsp;depth-first search (DFS) on the <code>root</code> of a binary tree.</p>
-
-<p>At each node in this traversal, we output <code>D</code> dashes (where <code>D</code> is the depth of this node), then we output the value of this node.&nbsp; If the depth of a node is <code>D</code>, the depth of its immediate child is <code>D + 1</code>.&nbsp; The depth of the <code>root</code> node is <code>0</code>.</p>
-
-<p>If a node has only one child, that child is guaranteed to be <strong>the left child</strong>.</p>
-
-<p>Given the output <code>traversal</code> of this traversal, recover the tree and return <em>its</em> <code>root</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/04/08/recover-a-tree-from-preorder-traversal.png" style="width: 320px; height: 200px;" />
-<pre>
-<strong>Input:</strong> traversal = &quot;1-2--3--4-5--6--7&quot;
-<strong>Output:</strong> [1,2,5,3,4,6,7]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/04/11/screen-shot-2019-04-10-at-114101-pm.png" style="width: 256px; height: 250px;" />
-<pre>
-<strong>Input:</strong> traversal = &quot;1-2--3---4-5--6---7&quot;
-<strong>Output:</strong> [1,2,5,3,null,6,null,4,null,7]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/04/11/screen-shot-2019-04-10-at-114955-pm.png" style="width: 276px; height: 250px;" />
-<pre>
-<strong>Input:</strong> traversal = &quot;1-401--349---90--88&quot;
-<strong>Output:</strong> [1,401,null,349,88,90]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the original tree is in the range <code>[1, 1000]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do an iterative depth first search, parsing dashes from the string to inform you how to link the nodes together.
-</details>
diff --git a/problems/recover-binary-search-tree/README.md b/problems/recover-binary-search-tree/README.md
deleted file mode 100644
index d8cfb5216..000000000
--- a/problems/recover-binary-search-tree/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../validate-binary-search-tree "Validate Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../same-tree "Same Tree")
-
-## [99. Recover Binary Search Tree (Medium)](https://leetcode.com/problems/recover-binary-search-tree "恢复二叉搜索树")
-
-<p>You are given the <code>root</code> of a binary search tree (BST), where the values of <strong>exactly</strong> two nodes of the tree were swapped by mistake. <em>Recover the tree without changing its structure</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/28/recover1.jpg" style="width: 422px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [1,3,null,null,2]
-<strong>Output:</strong> [3,1,null,null,2]
-<strong>Explanation:</strong> 3 cannot be a left child of 1 because 3 &gt; 1. Swapping 1 and 3 makes the BST valid.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/28/recover2.jpg" style="width: 581px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [3,1,4,null,null,2]
-<strong>Output:</strong> [2,1,4,null,null,3]
-<strong>Explanation:</strong> 2 cannot be in the right subtree of 3 because 2 &lt; 3. Swapping 2 and 3 makes the BST valid.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[2, 1000]</code>.</li>
-	<li><code>-2<sup>31</sup> &lt;= Node.val &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> A solution using <code>O(n)</code> space is pretty straight-forward. Could you devise a constant <code>O(1)</code> space solution?
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/recover-binary-search-tree/recover_binary_search_tree.go b/problems/recover-binary-search-tree/recover_binary_search_tree.go
deleted file mode 100644
index b072cd3e6..000000000
--- a/problems/recover-binary-search-tree/recover_binary_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem99
diff --git a/problems/recover-binary-search-tree/recover_binary_search_tree_test.go b/problems/recover-binary-search-tree/recover_binary_search_tree_test.go
deleted file mode 100644
index b072cd3e6..000000000
--- a/problems/recover-binary-search-tree/recover_binary_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem99
diff --git a/problems/recover-the-original-array/README.md b/problems/recover-the-original-array/README.md
deleted file mode 100644
index 31c4a2224..000000000
--- a/problems/recover-the-original-array/README.md
+++ /dev/null
@@ -1,95 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../intervals-between-identical-elements "Intervals Between Identical Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-operations-to-remove-adjacent-ones-in-matrix "Minimum Operations to Remove Adjacent Ones in Matrix")
-
-## [2122. Recover the Original Array (Hard)](https://leetcode.com/problems/recover-the-original-array "还原原数组")
-
-<p>Alice had a <strong>0-indexed</strong> array <code>arr</code> consisting of <code>n</code> <strong>positive</strong> integers. She chose an arbitrary <strong>positive integer</strong> <code>k</code> and created two new <strong>0-indexed</strong> integer arrays <code>lower</code> and <code>higher</code> in the following manner:</p>
-
-<ol>
-	<li><code>lower[i] = arr[i] - k</code>, for every index <code>i</code> where <code>0 &lt;= i &lt; n</code></li>
-	<li><code>higher[i] = arr[i] + k</code>, for every index <code>i</code> where <code>0 &lt;= i &lt; n</code></li>
-</ol>
-
-<p>Unfortunately, Alice lost all three arrays. However, she remembers the integers that were present in the arrays <code>lower</code> and <code>higher</code>, but not the array each integer belonged to. Help Alice and recover the original array.</p>
-
-<p>Given an array <code>nums</code> consisting of <code>2n</code> integers, where <strong>exactly</strong> <code>n</code> of the integers were present in <code>lower</code> and the remaining in <code>higher</code>, return <em>the <strong>original</strong> array</em> <code>arr</code>. In case the answer is not unique, return <em><strong>any</strong> valid array</em>.</p>
-
-<p><strong>Note:</strong> The test cases are generated such that there exists <strong>at least one</strong> valid array <code>arr</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,10,6,4,8,12]
-<strong>Output:</strong> [3,7,11]
-<strong>Explanation:</strong>
-If arr = [3,7,11] and k = 1, we get lower = [2,6,10] and higher = [4,8,12].
-Combining lower and higher gives us [2,6,10,4,8,12], which is a permutation of nums.
-Another valid possibility is that arr = [5,7,9] and k = 3. In that case, lower = [2,4,6] and higher = [8,10,12]. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,3,3]
-<strong>Output:</strong> [2,2]
-<strong>Explanation:</strong>
-If arr = [2,2] and k = 1, we get lower = [1,1] and higher = [3,3].
-Combining lower and higher gives us [1,1,3,3], which is equal to nums.
-Note that arr cannot be [1,3] because in that case, the only possible way to obtain [1,1,3,3] is with k = 0.
-This is invalid since k must be positive.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,435]
-<strong>Output:</strong> [220]
-<strong>Explanation:</strong>
-The only possible combination is arr = [220] and k = 215. Using them, we get lower = [5] and higher = [435].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 * n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li>The test cases are generated such that there exists <strong>at least one</strong> valid array <code>arr</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If we fix the value of k, how can we check if an original array exists for the fixed k?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The smallest value of nums is obtained by subtracting k from the smallest value of the original array. How can we use this to reduce the search space for finding a valid k?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can compute every possible k by using the smallest value of nums (as lower[i]) against every other value in nums (as the corresponding higher[i]).
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For every computed k, greedily pair up the values in nums. This can be done sorting nums, then using a map to store previous values and searching that map for a corresponding lower[i] for the current nums[j] (as higher[i]).
-</details>
diff --git a/problems/rectangle-area-ii/README.md b/problems/rectangle-area-ii/README.md
deleted file mode 100644
index b21a412dc..000000000
--- a/problems/rectangle-area-ii/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximize-distance-to-closest-person "Maximize Distance to Closest Person")
-　　　　　　　　　　　　　　　　
-[Next >](../loud-and-rich "Loud and Rich")
-
-## [850. Rectangle Area II (Hard)](https://leetcode.com/problems/rectangle-area-ii "矩形面积 II")
-
-<p>We are given a list of (axis-aligned) <code>rectangles</code>. Each <code>rectangle[i] = [x<sub>i1</sub>, y<sub>i1</sub>, x<sub>i2</sub>, y<sub>i2</sub>] </code>, where <code>(x<sub>i1</sub>, y<sub>i1</sub>)</code> are the coordinates of the bottom-left corner, and <code>(x<sub>i2</sub>, y<sub>i2</sub>)</code> are the coordinates of the top-right corner of the <code>i<sup>th</sup></code> rectangle.</p>
-
-<p>Find the total area covered by all <code>rectangles</code> in the plane. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/06/06/rectangle_area_ii_pic.png" style="width: 600px; height: 450px;" />
-<pre>
-<strong>Input:</strong> rectangles = [[0,0,2,2],[1,0,2,3],[1,0,3,1]]
-<strong>Output:</strong> 6
-<strong>Explanation: </strong>As illustrated in the picture.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rectangles = [[0,0,1000000000,1000000000]]
-<strong>Output:</strong> 49
-<strong>Explanation: </strong>The answer is 10<sup>18</sup> modulo (10<sup>9</sup> + 7), which is (10<sup>9</sup>)<sup>2</sup> = (-7)<sup>2</sup> = 49.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rectangles.length &lt;= 200</code></li>
-	<li><code><font face="monospace">rectanges[i].length = 4</font></code></li>
-	<li><code>0 &lt;= rectangles[i][j] &lt;= 10<sup>9</sup></code></li>
-	<li>The total area covered by all rectangles will never exceed <code>2<sup>63</sup> - 1</code> and thus will fit in a <strong>64-bit</strong> signed integer.</li>
-</ul>
-
-### Related Topics
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Line Sweep](../../tag/line-sweep/README.md)]
diff --git a/problems/rectangle-area-ii/rectangle_area_ii.go b/problems/rectangle-area-ii/rectangle_area_ii.go
deleted file mode 100644
index d6ebb203c..000000000
--- a/problems/rectangle-area-ii/rectangle_area_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem850
diff --git a/problems/rectangle-area-ii/rectangle_area_ii_test.go b/problems/rectangle-area-ii/rectangle_area_ii_test.go
deleted file mode 100644
index d6ebb203c..000000000
--- a/problems/rectangle-area-ii/rectangle_area_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem850
diff --git a/problems/rectangle-area/README.md b/problems/rectangle-area/README.md
deleted file mode 100644
index 1aad627f3..000000000
--- a/problems/rectangle-area/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-complete-tree-nodes "Count Complete Tree Nodes")
-　　　　　　　　　　　　　　　　
-[Next >](../basic-calculator "Basic Calculator")
-
-## [223. Rectangle Area (Medium)](https://leetcode.com/problems/rectangle-area "矩形面积")
-
-<p>Given the coordinates of two <strong>rectilinear</strong> rectangles in a 2D plane, return <em>the total area covered by the two rectangles</em>.</p>
-
-<p>The first rectangle is defined by its <strong>bottom-left</strong> corner <code>(ax1, ay1)</code> and its <strong>top-right</strong> corner <code>(ax2, ay2)</code>.</p>
-
-<p>The second rectangle is defined by its <strong>bottom-left</strong> corner <code>(bx1, by1)</code> and its <strong>top-right</strong> corner <code>(bx2, by2)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="Rectangle Area" src="https://assets.leetcode.com/uploads/2021/05/08/rectangle-plane.png" style="width: 700px; height: 365px;" />
-<pre>
-<strong>Input:</strong> ax1 = -3, ay1 = 0, ax2 = 3, ay2 = 4, bx1 = 0, by1 = -1, bx2 = 9, by2 = 2
-<strong>Output:</strong> 45
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> ax1 = -2, ay1 = -2, ax2 = 2, ay2 = 2, bx1 = -2, by1 = -2, bx2 = 2, by2 = 2
-<strong>Output:</strong> 16
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-10<sup>4</sup> &lt;= ax1, ay1, ax2, ay2, bx1, by1, bx2, by2 &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Rectangle Overlap](../rectangle-overlap) (Easy)
diff --git a/problems/rectangle-area/rectangle_area.go b/problems/rectangle-area/rectangle_area.go
deleted file mode 100644
index b12e64b6e..000000000
--- a/problems/rectangle-area/rectangle_area.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem223
diff --git a/problems/rectangle-area/rectangle_area_test.go b/problems/rectangle-area/rectangle_area_test.go
deleted file mode 100644
index b12e64b6e..000000000
--- a/problems/rectangle-area/rectangle_area_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem223
diff --git a/problems/rectangle-overlap/README.md b/problems/rectangle-overlap/README.md
deleted file mode 100644
index e5649b1d5..000000000
--- a/problems/rectangle-overlap/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../image-overlap "Image Overlap")
-　　　　　　　　　　　　　　　　
-[Next >](../new-21-game "New 21 Game")
-
-## [836. Rectangle Overlap (Easy)](https://leetcode.com/problems/rectangle-overlap "矩形重叠")
-
-<p>An axis-aligned rectangle is represented as a list <code>[x1, y1, x2, y2]</code>, where <code>(x1, y1)</code> is the coordinate of its bottom-left corner, and <code>(x2, y2)</code> is the coordinate of its top-right corner. Its top and bottom edges are parallel to the X-axis, and its left and right edges are parallel to the Y-axis.</p>
-
-<p>Two rectangles overlap if the area of their intersection is <strong>positive</strong>. To be clear, two rectangles that only touch at the corner or edges do not overlap.</p>
-
-<p>Given two axis-aligned rectangles <code>rec1</code> and <code>rec2</code>, return <code>true</code><em> if they overlap, otherwise return </em><code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> rec1 = [0,0,2,2], rec2 = [1,1,3,3]
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> rec1 = [0,0,1,1], rec2 = [1,0,2,1]
-<strong>Output:</strong> false
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> rec1 = [0,0,1,1], rec2 = [2,2,3,3]
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>rect1.length == 4</code></li>
-	<li><code>rect2.length == 4</code></li>
-	<li><code>-10<sup>9</sup> &lt;= rec1[i], rec2[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>rec1</code> and <code>rec2</code> represent a valid rectangle with a non-zero area.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Geometry](../../tag/geometry/README.md)]
-
-### Similar Questions
-  1. [Rectangle Area](../rectangle-area) (Medium)
diff --git a/problems/rectangle-overlap/rectangle_overlap.go b/problems/rectangle-overlap/rectangle_overlap.go
deleted file mode 100644
index 1304599f8..000000000
--- a/problems/rectangle-overlap/rectangle_overlap.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem836
diff --git a/problems/rectangle-overlap/rectangle_overlap_test.go b/problems/rectangle-overlap/rectangle_overlap_test.go
deleted file mode 100644
index 1304599f8..000000000
--- a/problems/rectangle-overlap/rectangle_overlap_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem836
diff --git a/problems/rectangles-area/README.md b/problems/rectangles-area/README.md
deleted file mode 100644
index f64effc69..000000000
--- a/problems/rectangles-area/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-dot-product-of-two-subsequences "Max Dot Product of Two Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../make-two-arrays-equal-by-reversing-sub-arrays "Make Two Arrays Equal by Reversing Sub-arrays")
-
-## [1459. Rectangles Area (Medium)](https://leetcode.com/problems/rectangles-area "矩形面积")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/rectangles-area/mysql_schemas.sql b/problems/rectangles-area/mysql_schemas.sql
deleted file mode 100644
index 63988bb64..000000000
--- a/problems/rectangles-area/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create table If Not Exists Points (id int, x_value int, y_value int);
-Truncate table Points;
-insert into Points (id, x_value, y_value) values ('1', '2', '7');
-insert into Points (id, x_value, y_value) values ('2', '4', '8');
-insert into Points (id, x_value, y_value) values ('3', '2', '10');
diff --git a/problems/recyclable-and-low-fat-products/README.md b/problems/recyclable-and-low-fat-products/README.md
deleted file mode 100644
index 1bb3bbf66..000000000
--- a/problems/recyclable-and-low-fat-products/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-most-recently-used-queue "Design Most Recently Used Queue")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-changes-to-make-alternating-binary-string "Minimum Changes To Make Alternating Binary String")
-
-## [1757. Recyclable and Low Fat Products (Easy)](https://leetcode.com/problems/recyclable-and-low-fat-products "可回收且低脂的产品")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/recyclable-and-low-fat-products/mysql_schemas.sql b/problems/recyclable-and-low-fat-products/mysql_schemas.sql
deleted file mode 100644
index bffc7a5fb..000000000
--- a/problems/recyclable-and-low-fat-products/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Products (product_id int, low_fats ENUM('Y', 'N'), recyclable ENUM('Y','N'));
-Truncate table Products;
-insert into Products (product_id, low_fats, recyclable) values ('0', 'Y', 'N');
-insert into Products (product_id, low_fats, recyclable) values ('1', 'Y', 'Y');
-insert into Products (product_id, low_fats, recyclable) values ('2', 'N', 'Y');
-insert into Products (product_id, low_fats, recyclable) values ('3', 'Y', 'Y');
-insert into Products (product_id, low_fats, recyclable) values ('4', 'N', 'N');
diff --git a/problems/redistribute-characters-to-make-all-strings-equal/README.md b/problems/redistribute-characters-to-make-all-strings-equal/README.md
deleted file mode 100644
index 267df957b..000000000
--- a/problems/redistribute-characters-to-make-all-strings-equal/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-change-the-final-value-of-expression "Minimum Cost to Change the Final Value of Expression")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-removable-characters "Maximum Number of Removable Characters")
-
-## [1897. Redistribute Characters to Make All Strings Equal (Easy)](https://leetcode.com/problems/redistribute-characters-to-make-all-strings-equal "重新分配字符使所有字符串都相等")
-
-<p>You are given an array of strings <code>words</code> (<strong>0-indexed</strong>).</p>
-
-<p>In one operation, pick two <strong>distinct</strong> indices <code>i</code> and <code>j</code>, where <code>words[i]</code> is a non-empty string, and move <strong>any</strong> character from <code>words[i]</code> to <strong>any</strong> position in <code>words[j]</code>.</p>
-
-<p>Return <code>true</code> <em>if you can make<strong> every</strong> string in </em><code>words</code><em> <strong>equal </strong>using <strong>any</strong> number of operations</em>,<em> and </em><code>false</code> <em>otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;abc&quot;,&quot;aabc&quot;,&quot;bc&quot;]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Move the first &#39;a&#39; in <code>words[1] to the front of words[2],
-to make </code><code>words[1]</code> = &quot;abc&quot; and words[2] = &quot;abc&quot;.
-All the strings are now equal to &quot;abc&quot;, so return <code>true</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;ab&quot;,&quot;a&quot;]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to make all the strings equal using the operation.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 100</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 100</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Characters are independent—only the frequency of characters matters.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-It is possible to distribute characters if all characters can be divided equally among all strings.
-</details>
diff --git a/problems/reduce-array-size-to-the-half/README.md b/problems/reduce-array-size-to-the-half/README.md
deleted file mode 100644
index 7dcae1f59..000000000
--- a/problems/reduce-array-size-to-the-half/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-k-weakest-rows-in-a-matrix "The K Weakest Rows in a Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-product-of-splitted-binary-tree "Maximum Product of Splitted Binary Tree")
-
-## [1338. Reduce Array Size to The Half (Medium)](https://leetcode.com/problems/reduce-array-size-to-the-half "数组大小减半")
-
-<p>You are given an integer array <code>arr</code>. You can choose a set of integers and remove all the occurrences of these integers in the array.</p>
-
-<p>Return <em>the minimum size of the set so that <strong>at least</strong> half of the integers of the array are removed</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,3,3,3,5,5,5,2,2,7]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Choosing {3,7} will make the new array [5,5,5,2,2] which has size 5 (i.e equal to half of the size of the old array).
-Possible sets of size 2 are {3,5},{3,2},{5,2}.
-Choosing set {2,7} is not possible as it will make the new array [3,3,3,3,5,5,5] which has a size greater than half of the size of the old array.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [7,7,7,7,7,7]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only possible set you can choose is {7}. This will make the new array empty.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>arr.length</code> is even.</li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the frequency of each integer in the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Start with an empty set, add to the set the integer with the maximum frequency.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Keep Adding the integer with the max frequency until you remove at least half of the integers.
-</details>
diff --git a/problems/reducing-dishes/README.md b/problems/reducing-dishes/README.md
deleted file mode 100644
index c17b51662..000000000
--- a/problems/reducing-dishes/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../circle-and-rectangle-overlapping "Circle and Rectangle Overlapping")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-subsequence-in-non-increasing-order "Minimum Subsequence in Non-Increasing Order")
-
-## [1402. Reducing Dishes (Hard)](https://leetcode.com/problems/reducing-dishes "做菜顺序")
-
-<p>A chef has collected data on the <code>satisfaction</code> level of his <code>n</code> dishes. Chef can cook any dish in 1 unit of time.</p>
-
-<p><strong>Like-time coefficient</strong> of a dish is defined as the time taken to cook that dish including previous dishes multiplied by its satisfaction level i.e. <code>time[i] * satisfaction[i]</code>.</p>
-
-<p>Return <em>the maximum sum of <strong>like-time coefficient</strong> that the chef can obtain after dishes preparation</em>.</p>
-
-<p>Dishes can be prepared in <strong>any </strong>order and the chef can discard some dishes to get this maximum value.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> satisfaction = [-1,-8,0,5,-9]
-<strong>Output:</strong> 14
-<strong>Explanation:</strong> After Removing the second and last dish, the maximum total <strong>like-time coefficient</strong> will be equal to (-1*1 + 0*2 + 5*3 = 14).
-Each dish is prepared in one unit of time.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> satisfaction = [4,3,2]
-<strong>Output:</strong> 20
-<strong>Explanation:</strong> Dishes can be prepared in any order, (2*1 + 3*2 + 4*3 = 20)
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> satisfaction = [-1,-4,-5]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> People do not like the dishes. No dish is prepared.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == satisfaction.length</code></li>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-	<li><code>-1000 &lt;= satisfaction[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming to find the optimal solution by saving the previous best like-time coefficient and its corresponding element sum.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If adding the current element to the previous best like-time coefficient and its corresponding element sum would increase the best like-time coefficient, then go ahead and add it. Otherwise, keep the previous best like-time coefficient.
-</details>
diff --git a/problems/reduction-operations-to-make-the-array-elements-equal/README.md b/problems/reduction-operations-to-make-the-array-elements-equal/README.md
deleted file mode 100644
index f165aae46..000000000
--- a/problems/reduction-operations-to-make-the-array-elements-equal/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../determine-whether-matrix-can-be-obtained-by-rotation "Determine Whether Matrix Can Be Obtained By Rotation")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-flips-to-make-the-binary-string-alternating "Minimum Number of Flips to Make the Binary String Alternating")
-
-## [1887. Reduction Operations to Make the Array Elements Equal (Medium)](https://leetcode.com/problems/reduction-operations-to-make-the-array-elements-equal "使数组元素相等的减少操作次数")
-
-<p>Given an integer array <code>nums</code>, your goal is to make all elements in <code>nums</code> equal. To complete one operation, follow these steps:</p>
-
-<ol>
-	<li>Find the <strong>largest</strong> value in <code>nums</code>. Let its index be <code>i</code> (<strong>0-indexed</strong>) and its value be <code>largest</code>. If there are multiple elements with the largest value, pick the smallest <code>i</code>.</li>
-	<li>Find the <strong>next largest</strong> value in <code>nums</code> <strong>strictly smaller</strong> than <code>largest</code>. Let its value be <code>nextLargest</code>.</li>
-	<li>Reduce <code>nums[i]</code> to <code>nextLargest</code>.</li>
-</ol>
-
-<p>Return <em>the number of operations to make all elements in </em><code>nums</code><em> equal</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,1,3]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>&nbsp;It takes 3 operations to make all elements in nums equal:
-1. largest = 5 at index 0. nextLargest = 3. Reduce nums[0] to 3. nums = [<u>3</u>,1,3].
-2. largest = 3 at index 0. nextLargest = 1. Reduce nums[0] to 1. nums = [<u>1</u>,1,3].
-3. largest = 3 at index 2. nextLargest = 1. Reduce nums[2] to 1. nums = [1,1,<u>1</u>].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>&nbsp;All elements in nums are already equal.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,2,2,3]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong>&nbsp;It takes 4 operations to make all elements in nums equal:
-1. largest = 3 at index 4. nextLargest = 2. Reduce nums[4] to 2. nums = [1,1,2,2,<u>2</u>].
-2. largest = 2 at index 2. nextLargest = 1. Reduce nums[2] to 1. nums = [1,1,<u>1</u>,2,2].
-3. largest = 2 at index 3. nextLargest = 1. Reduce nums[3] to 1. nums = [1,1,1,<u>1</u>,2].
-4. largest = 2 at index 4. nextLargest = 1. Reduce nums[4] to 1. nums = [1,1,1,1,<u>1</u>].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 5 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try to reduce all elements with maximum value to the next maximum value in one operation.
-</details>
diff --git a/problems/redundant-connection-ii/README.md b/problems/redundant-connection-ii/README.md
deleted file mode 100644
index 5d2839c69..000000000
--- a/problems/redundant-connection-ii/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../redundant-connection "Redundant Connection")
-　　　　　　　　　　　　　　　　
-[Next >](../repeated-string-match "Repeated String Match")
-
-## [685. Redundant Connection II (Hard)](https://leetcode.com/problems/redundant-connection-ii "冗余连接 II")
-
-<p>In this problem, a rooted tree is a <b>directed</b> graph such that, there is exactly one node (the root) for which all other nodes are descendants of this node, plus every node has exactly one parent, except for the root node which has no parents.</p>
-
-<p>The given input is a directed graph that started as a rooted tree with <code>n</code> nodes (with distinct values from <code>1</code> to <code>n</code>), with one additional directed edge added. The added edge has two different vertices chosen from <code>1</code> to <code>n</code>, and was not an edge that already existed.</p>
-
-<p>The resulting graph is given as a 2D-array of <code>edges</code>. Each element of <code>edges</code> is a pair <code>[u<sub>i</sub>, v<sub>i</sub>]</code> that represents a <b>directed</b> edge connecting nodes <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code>, where <code>u<sub>i</sub></code> is a parent of child <code>v<sub>i</sub></code>.</p>
-
-<p>Return <em>an edge that can be removed so that the resulting graph is a rooted tree of</em> <code>n</code> <em>nodes</em>. If there are multiple answers, return the answer that occurs last in the given 2D-array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/20/graph1.jpg" style="width: 222px; height: 222px;" />
-<pre>
-<strong>Input:</strong> edges = [[1,2],[1,3],[2,3]]
-<strong>Output:</strong> [2,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/20/graph2.jpg" style="width: 222px; height: 382px;" />
-<pre>
-<strong>Input:</strong> edges = [[1,2],[2,3],[3,4],[4,1],[1,5]]
-<strong>Output:</strong> [4,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == edges.length</code></li>
-	<li><code>3 &lt;= n &lt;= 1000</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>1 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n</code></li>
-	<li><code>u<sub>i</sub> != v<sub>i</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [Redundant Connection](../redundant-connection) (Medium)
diff --git a/problems/redundant-connection-ii/redundant_connection_ii.go b/problems/redundant-connection-ii/redundant_connection_ii.go
deleted file mode 100644
index 59da76b1a..000000000
--- a/problems/redundant-connection-ii/redundant_connection_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem685
diff --git a/problems/redundant-connection-ii/redundant_connection_ii_test.go b/problems/redundant-connection-ii/redundant_connection_ii_test.go
deleted file mode 100644
index 59da76b1a..000000000
--- a/problems/redundant-connection-ii/redundant_connection_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem685
diff --git a/problems/redundant-connection/README.md b/problems/redundant-connection/README.md
deleted file mode 100644
index 4835b8bf1..000000000
--- a/problems/redundant-connection/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-empty-slots "K Empty Slots")
-　　　　　　　　　　　　　　　　
-[Next >](../redundant-connection-ii "Redundant Connection II")
-
-## [684. Redundant Connection (Medium)](https://leetcode.com/problems/redundant-connection "冗余连接")
-
-<p>In this problem, a tree is an <strong>undirected graph</strong> that is connected and has no cycles.</p>
-
-<p>You are given a graph that started as a tree with <code>n</code> nodes labeled from <code>1</code> to <code>n</code>, with one additional edge added. The added edge has two <strong>different</strong> vertices chosen from <code>1</code> to <code>n</code>, and was not an edge that already existed. The graph is represented as an array <code>edges</code> of length <code>n</code> where <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that there is an edge between nodes <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code> in the graph.</p>
-
-<p>Return <em>an edge that can be removed so that the resulting graph is a tree of </em><code>n</code><em> nodes</em>. If there are multiple answers, return the answer that occurs last in the input.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/02/reduntant1-1-graph.jpg" style="width: 222px; height: 222px;" />
-<pre>
-<strong>Input:</strong> edges = [[1,2],[1,3],[2,3]]
-<strong>Output:</strong> [2,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/02/reduntant1-2-graph.jpg" style="width: 382px; height: 222px;" />
-<pre>
-<strong>Input:</strong> edges = [[1,2],[2,3],[3,4],[1,4],[1,5]]
-<strong>Output:</strong> [1,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == edges.length</code></li>
-	<li><code>3 &lt;= n &lt;= 1000</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>1 &lt;= a<sub>i</sub> &lt; b<sub>i</sub> &lt;= edges.length</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-	<li>There are no repeated edges.</li>
-	<li>The given graph is connected.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [Redundant Connection II](../redundant-connection-ii) (Hard)
-  1. [Accounts Merge](../accounts-merge) (Medium)
diff --git a/problems/redundant-connection/redundant_connection.go b/problems/redundant-connection/redundant_connection.go
deleted file mode 100644
index 46843876d..000000000
--- a/problems/redundant-connection/redundant_connection.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem684
diff --git a/problems/redundant-connection/redundant_connection_test.go b/problems/redundant-connection/redundant_connection_test.go
deleted file mode 100644
index 46843876d..000000000
--- a/problems/redundant-connection/redundant_connection_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem684
diff --git a/problems/reformat-date/README.md b/problems/reformat-date/README.md
deleted file mode 100644
index c75714512..000000000
--- a/problems/reformat-date/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-root-of-n-ary-tree "Find Root of N-Ary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../range-sum-of-sorted-subarray-sums "Range Sum of Sorted Subarray Sums")
-
-## [1507. Reformat Date (Easy)](https://leetcode.com/problems/reformat-date "转变日期格式")
-
-<p>Given a <code>date</code> string in the form&nbsp;<code>Day Month Year</code>, where:</p>
-
-<ul>
-	<li><code>Day</code>&nbsp;is in the set <code>{&quot;1st&quot;, &quot;2nd&quot;, &quot;3rd&quot;, &quot;4th&quot;, ..., &quot;30th&quot;, &quot;31st&quot;}</code>.</li>
-	<li><code>Month</code>&nbsp;is in the set <code>{&quot;Jan&quot;, &quot;Feb&quot;, &quot;Mar&quot;, &quot;Apr&quot;, &quot;May&quot;, &quot;Jun&quot;, &quot;Jul&quot;, &quot;Aug&quot;, &quot;Sep&quot;, &quot;Oct&quot;, &quot;Nov&quot;, &quot;Dec&quot;}</code>.</li>
-	<li><code>Year</code>&nbsp;is in the range <code>[1900, 2100]</code>.</li>
-</ul>
-
-<p>Convert the date string to the format <code>YYYY-MM-DD</code>, where:</p>
-
-<ul>
-	<li><code>YYYY</code> denotes the 4 digit year.</li>
-	<li><code>MM</code> denotes the 2 digit month.</li>
-	<li><code>DD</code> denotes the 2 digit day.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> date = &quot;20th Oct 2052&quot;
-<strong>Output:</strong> &quot;2052-10-20&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> date = &quot;6th Jun 1933&quot;
-<strong>Output:</strong> &quot;1933-06-06&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> date = &quot;26th May 1960&quot;
-<strong>Output:</strong> &quot;1960-05-26&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The given dates are guaranteed to be valid, so no error handling is necessary.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Handle the conversions of day, month and year separately.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Notice that days always have a two-word ending, so if you erase the last two characters of this days you'll get the number.
-</details>
diff --git a/problems/reformat-department-table/README.md b/problems/reformat-department-table/README.md
deleted file mode 100644
index 22185b884..000000000
--- a/problems/reformat-department-table/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-valid-words-for-each-puzzle "Number of Valid Words for Each Puzzle")
-　　　　　　　　　　　　　　　　
-[Next >](../count-substrings-with-only-one-distinct-letter "Count Substrings with Only One Distinct Letter")
-
-## [1179. Reformat Department Table (Easy)](https://leetcode.com/problems/reformat-department-table "重新格式化部门表")
-
-<p>Table: <code>Department</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| id          | int     |
-| revenue     | int     |
-| month       | varchar |
-+-------------+---------+
-(id, month) is the primary key of this table.
-The table has information about the revenue of each department per month.
-The month has values in [&quot;Jan&quot;,&quot;Feb&quot;,&quot;Mar&quot;,&quot;Apr&quot;,&quot;May&quot;,&quot;Jun&quot;,&quot;Jul&quot;,&quot;Aug&quot;,&quot;Sep&quot;,&quot;Oct&quot;,&quot;Nov&quot;,&quot;Dec&quot;].
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to reformat the table such that there is a department id column and a revenue column <strong>for each month</strong>.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Department table:
-+------+---------+-------+
-| id   | revenue | month |
-+------+---------+-------+
-| 1    | 8000    | Jan   |
-| 2    | 9000    | Jan   |
-| 3    | 10000   | Feb   |
-| 1    | 7000    | Feb   |
-| 1    | 6000    | Mar   |
-+------+---------+-------+
-<strong>Output:</strong> 
-+------+-------------+-------------+-------------+-----+-------------+
-| id   | Jan_Revenue | Feb_Revenue | Mar_Revenue | ... | Dec_Revenue |
-+------+-------------+-------------+-------------+-----+-------------+
-| 1    | 8000        | 7000        | 6000        | ... | null        |
-| 2    | 9000        | null        | null        | ... | null        |
-| 3    | null        | 10000       | null        | ... | null        |
-+------+-------------+-------------+-------------+-----+-------------+
-<strong>Explanation:</strong> The revenue from Apr to Dec is null.
-Note that the result table has 13 columns (1 for the department id + 12 for the months).
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/reformat-department-table/mysql_schemas.sql b/problems/reformat-department-table/mysql_schemas.sql
deleted file mode 100644
index 1c652dfcf..000000000
--- a/problems/reformat-department-table/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Department (id int, revenue int, month varchar(5));
-Truncate table Department;
-insert into Department (id, revenue, month) values ('1', '8000', 'Jan');
-insert into Department (id, revenue, month) values ('2', '9000', 'Jan');
-insert into Department (id, revenue, month) values ('3', '10000', 'Feb');
-insert into Department (id, revenue, month) values ('1', '7000', 'Feb');
-insert into Department (id, revenue, month) values ('1', '6000', 'Mar');
diff --git a/problems/reformat-phone-number/README.md b/problems/reformat-phone-number/README.md
deleted file mode 100644
index d4dc85908..000000000
--- a/problems/reformat-phone-number/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../daily-leads-and-partners "Daily Leads and Partners")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-erasure-value "Maximum Erasure Value")
-
-## [1694. Reformat Phone Number (Easy)](https://leetcode.com/problems/reformat-phone-number "重新格式化电话号码")
-
-<p>You are given a phone number as a string <code>number</code>. <code>number</code> consists of digits, spaces <code>&#39; &#39;</code>, and/or dashes <code>&#39;-&#39;</code>.</p>
-
-<p>You would like to reformat the phone number in a certain manner. Firstly, <strong>remove</strong> all spaces and dashes. Then, <strong>group</strong> the digits from left to right into blocks of length 3 <strong>until</strong> there are 4 or fewer digits. The final digits are then grouped as follows:</p>
-
-<ul>
-	<li>2 digits: A single block of length 2.</li>
-	<li>3 digits: A single block of length 3.</li>
-	<li>4 digits: Two blocks of length 2 each.</li>
-</ul>
-
-<p>The blocks are then joined by dashes. Notice that the reformatting process should <strong>never</strong> produce any blocks of length 1 and produce <strong>at most</strong> two blocks of length 2.</p>
-
-<p>Return <em>the phone number after formatting.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> number = &quot;1-23-45 6&quot;
-<strong>Output:</strong> &quot;123-456&quot;
-<strong>Explanation:</strong> The digits are &quot;123456&quot;.
-Step 1: There are more than 4 digits, so group the next 3 digits. The 1st block is &quot;123&quot;.
-Step 2: There are 3 digits remaining, so put them in a single block of length 3. The 2nd block is &quot;456&quot;.
-Joining the blocks gives &quot;123-456&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> number = &quot;123 4-567&quot;
-<strong>Output:</strong> &quot;123-45-67&quot;
-<strong>Explanation: </strong>The digits are &quot;1234567&quot;.
-Step 1: There are more than 4 digits, so group the next 3 digits. The 1st block is &quot;123&quot;.
-Step 2: There are 4 digits left, so split them into two blocks of length 2. The blocks are &quot;45&quot; and &quot;67&quot;.
-Joining the blocks gives &quot;123-45-67&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> number = &quot;123 4-5678&quot;
-<strong>Output:</strong> &quot;123-456-78&quot;
-<strong>Explanation:</strong> The digits are &quot;12345678&quot;.
-Step 1: The 1st block is &quot;123&quot;.
-Step 2: The 2nd block is &quot;456&quot;.
-Step 3: There are 2 digits left, so put them in a single block of length 2. The 3rd block is &quot;78&quot;.
-Joining the blocks gives &quot;123-456-78&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= number.length &lt;= 100</code></li>
-	<li><code>number</code> consists of digits and the characters <code>&#39;-&#39;</code> and <code>&#39; &#39;</code>.</li>
-	<li>There are at least <strong>two</strong> digits in <code>number</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Discard all the spaces and dashes.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a while loop. While the string still has digits, check its length and see which rule to apply.
-</details>
diff --git a/problems/reformat-the-string/README.md b/problems/reformat-the-string/README.md
deleted file mode 100644
index 9b928f238..000000000
--- a/problems/reformat-the-string/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../restore-the-array "Restore The Array")
-　　　　　　　　　　　　　　　　
-[Next >](../display-table-of-food-orders-in-a-restaurant "Display Table of Food Orders in a Restaurant")
-
-## [1417. Reformat The String (Easy)](https://leetcode.com/problems/reformat-the-string "重新格式化字符串")
-
-<p>Given alphanumeric string <code>s</code>. (<strong>Alphanumeric string</strong> is a string consisting of lowercase English letters and digits).</p>
-
-<p>You have to find a permutation of&nbsp;the string where no letter is followed by another letter and no digit is followed by another digit. That is, no two adjacent characters have the same type.</p>
-
-<p>Return <em>the reformatted string</em> or return <strong>an empty string</strong> if it is impossible to reformat the string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a0b1c2&quot;
-<strong>Output:</strong> &quot;0a1b2c&quot;
-<strong>Explanation:</strong> No two adjacent characters have the same type in &quot;0a1b2c&quot;. &quot;a0b1c2&quot;, &quot;0a1b2c&quot;, &quot;0c2a1b&quot; are also valid permutations.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> &quot;leetcode&quot; has only characters so we cannot separate them by digits.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1229857369&quot;
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> &quot;1229857369&quot; has only digits so we cannot separate them by characters.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;covid2019&quot;
-<strong>Output:</strong> &quot;c2o0v1i9d&quot;
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ab123&quot;
-<strong>Output:</strong> &quot;1a2b3&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 500</code></li>
-	<li><code>s</code> consists of only lowercase English letters and/or digits.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the number of letters and digits in the string. if cntLetters - cntDigits has any of the values [-1, 0, 1] we have an answer, otherwise we don't have any answer.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Build the string anyway as you wish. Keep in mind that you need to start with the type that have more characters if cntLetters ≠ cntDigits.
-</details>
diff --git a/problems/reformat-the-string/reformat_the_string.go b/problems/reformat-the-string/reformat_the_string.go
deleted file mode 100644
index 840d70c1d..000000000
--- a/problems/reformat-the-string/reformat_the_string.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package problem1417
-
-func reformat(s string) string {
-	i, j, l := 0, 1, len(s)
-	str := make([]byte, l+1)
-	for _, c := range s {
-		if '0' <= c && c <= '9' {
-			if i > l {
-				return ""
-			}
-			str[i], i = byte(c), i+2
-		} else if j > l {
-			return ""
-		} else {
-			str[j], j = byte(c), j+2
-		}
-	}
-	if i == l || j == l {
-		return string(str[:l])
-	}
-	if i == l-1 {
-		str[i] = str[0]
-		return string(str[1 : l+1])
-	}
-	return ""
-}
diff --git a/problems/reformat-the-string/reformat_the_string_test.go b/problems/reformat-the-string/reformat_the_string_test.go
deleted file mode 100644
index 691a6f023..000000000
--- a/problems/reformat-the-string/reformat_the_string_test.go
+++ /dev/null
@@ -1,63 +0,0 @@
-package problem1417
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestReformat(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "a0b1c2",
-			want: "0a1b2c",
-		},
-		{
-			in:   "leetcode",
-			want: "",
-		},
-		{
-			in:   "1229857369",
-			want: "",
-		},
-		{
-			in:   "covid2019",
-			want: "c0o1v9i2d",
-		},
-		{
-			in:   "ab123",
-			want: "1a2b3",
-		},
-		{
-			in:   "ec",
-			want: "",
-		},
-		{
-			in:   "abcd12345",
-			want: "1a2b3c4d5",
-		},
-		{
-			in:   "12345abcd",
-			want: "1a2b3c4d5",
-		},
-		{
-			in:   "77",
-			want: "",
-		},
-		{
-			in:   "1",
-			want: "1",
-		},
-		{
-			in:   "a",
-			want: "a",
-		},
-	}
-	for _, tt := range tests {
-		got := reformat(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/regions-cut-by-slashes/README.md b/problems/regions-cut-by-slashes/README.md
deleted file mode 100644
index a92996173..000000000
--- a/problems/regions-cut-by-slashes/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-completeness-of-a-binary-tree "Check Completeness of a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-columns-to-make-sorted-iii "Delete Columns to Make Sorted III")
-
-## [959. Regions Cut By Slashes (Medium)](https://leetcode.com/problems/regions-cut-by-slashes "由斜杠划分区域")
-
-<p>An <code>n x n</code> grid is composed of <code>1 x 1</code> squares where each <code>1 x 1</code> square consists of a <code>&#39;/&#39;</code>, <code>&#39;\&#39;</code>, or blank space <code>&#39; &#39;</code>. These characters divide the square into contiguous regions.</p>
-
-<p>Given the grid <code>grid</code> represented as a string array, return <em>the number of regions</em>.</p>
-
-<p>Note that backslash characters are escaped, so a <code>&#39;\&#39;</code> is represented as <code>&#39;\\&#39;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/1.png" style="width: 200px; height: 200px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot; /&quot;,&quot;/ &quot;]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/2.png" style="width: 200px; height: 198px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot; /&quot;,&quot;  &quot;]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/3.png" style="width: 200px; height: 198px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot;\\/&quot;,&quot;/\\&quot;]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>(Recall that because \ characters are escaped, &quot;\\/&quot; refers to \/, and &quot;/\\&quot; refers to /\.)
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/4.png" style="width: 200px; height: 200px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot;/\\&quot;,&quot;\\/&quot;]
-<strong>Output:</strong> 5
-<strong>Explanation: </strong>(Recall that because \ characters are escaped, &quot;\\/&quot; refers to \/, and &quot;/\\&quot; refers to /\.)
-</pre>
-
-<p><strong>Example 5:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/5.png" style="width: 200px; height: 200px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot;//&quot;,&quot;/ &quot;]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 30</code></li>
-	<li><code>grid[i][j]</code> is either <code>&#39;/&#39;</code>, <code>&#39;\&#39;</code>, or <code>&#39; &#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
diff --git a/problems/regions-cut-by-slashes/regions_cut_by_slashes.go b/problems/regions-cut-by-slashes/regions_cut_by_slashes.go
deleted file mode 100644
index bdb76cedb..000000000
--- a/problems/regions-cut-by-slashes/regions_cut_by_slashes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem959
diff --git a/problems/regions-cut-by-slashes/regions_cut_by_slashes_test.go b/problems/regions-cut-by-slashes/regions_cut_by_slashes_test.go
deleted file mode 100644
index bdb76cedb..000000000
--- a/problems/regions-cut-by-slashes/regions_cut_by_slashes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem959
diff --git a/problems/regular-expression-matching/README.md b/problems/regular-expression-matching/README.md
deleted file mode 100644
index 70b91192d..000000000
--- a/problems/regular-expression-matching/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-number "Palindrome Number")
-　　　　　　　　　　　　　　　　
-[Next >](../container-with-most-water "Container With Most Water")
-
-## [10. Regular Expression Matching (Hard)](https://leetcode.com/problems/regular-expression-matching "正则表达式匹配")
-
-<p>Given an input string <code>s</code>&nbsp;and a pattern <code>p</code>, implement regular expression matching with support for <code>&#39;.&#39;</code> and <code>&#39;*&#39;</code> where:</p>
-
-<ul>
-	<li><code>&#39;.&#39;</code> Matches any single character.​​​​</li>
-	<li><code>&#39;*&#39;</code> Matches zero or more of the preceding element.</li>
-</ul>
-
-<p>The matching should cover the <strong>entire</strong> input string (not partial).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aa&quot;, p = &quot;a&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> &quot;a&quot; does not match the entire string &quot;aa&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aa&quot;, p = &quot;a*&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>&nbsp;&#39;*&#39; means zero or more of the preceding&nbsp;element, &#39;a&#39;. Therefore, by repeating &#39;a&#39; once, it becomes &quot;aa&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ab&quot;, p = &quot;.*&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>&nbsp;&quot;.*&quot; means &quot;zero or more (*) of any character (.)&quot;.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aab&quot;, p = &quot;c*a*b&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>&nbsp;c can be repeated 0 times, a can be repeated 1 time. Therefore, it matches &quot;aab&quot;.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;mississippi&quot;, p = &quot;mis*is*p*.&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length&nbsp;&lt;= 20</code></li>
-	<li><code>1 &lt;= p.length&nbsp;&lt;= 30</code></li>
-	<li><code>s</code> contains only lowercase English letters.</li>
-	<li><code>p</code> contains only lowercase English letters, <code>&#39;.&#39;</code>, and&nbsp;<code>&#39;*&#39;</code>.</li>
-	<li>It is guaranteed for each appearance of the character <code>&#39;*&#39;</code>, there will be a previous valid character to match.</li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Wildcard Matching](../wildcard-matching) (Hard)
diff --git a/problems/regular-expression-matching/regular_expression_matching.go b/problems/regular-expression-matching/regular_expression_matching.go
deleted file mode 100644
index 3bd648cda..000000000
--- a/problems/regular-expression-matching/regular_expression_matching.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package problem10
-
-import "regexp"
-
-func isMatch(s string, p string) bool {
-	reg := regexp.MustCompile(p)
-	res := reg.FindAllString(s, 1)
-	return len(res) == 1 && res[0] == s
-}
diff --git a/problems/regular-expression-matching/regular_expression_matching_test.go b/problems/regular-expression-matching/regular_expression_matching_test.go
deleted file mode 100644
index e8d3ca781..000000000
--- a/problems/regular-expression-matching/regular_expression_matching_test.go
+++ /dev/null
@@ -1,50 +0,0 @@
-package problem10
-
-import "testing"
-
-type testType struct {
-	s    string
-	p    string
-	want bool
-}
-
-func TestIsMatch(t *testing.T) {
-	tests := [...]testType{
-		{
-			s:    "aa",
-			p:    "a",
-			want: false,
-		},
-		{
-			s:    "aa",
-			p:    "a*",
-			want: true,
-		},
-		{
-			s:    "ab",
-			p:    ".*",
-			want: true,
-		},
-		{
-			s:    "aab",
-			p:    "c*a*b",
-			want: true,
-		},
-		{
-			s:    "mississippi",
-			p:    "mis*is*p*.",
-			want: false,
-		},
-		{
-			s:    "",
-			p:    ".",
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isMatch(tt.s, tt.p)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.s, tt.p, got, tt.want)
-		}
-	}
-}
diff --git a/problems/relative-ranks/README.md b/problems/relative-ranks/README.md
deleted file mode 100644
index 16519bc3b..000000000
--- a/problems/relative-ranks/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-maze-ii "The Maze II")
-　　　　　　　　　　　　　　　　
-[Next >](../perfect-number "Perfect Number")
-
-## [506. Relative Ranks (Easy)](https://leetcode.com/problems/relative-ranks "相对名次")
-
-<p>You are given an integer array <code>score</code> of size <code>n</code>, where <code>score[i]</code> is the score of the <code>i<sup>th</sup></code> athlete in a competition. All the scores are guaranteed to be <strong>unique</strong>.</p>
-
-<p>The athletes are <strong>placed</strong> based on their scores, where the <code>1<sup>st</sup></code> place athlete has the highest score, the <code>2<sup>nd</sup></code> place athlete has the <code>2<sup>nd</sup></code> highest score, and so on. The placement of each athlete determines their rank:</p>
-
-<ul>
-	<li>The <code>1<sup>st</sup></code> place athlete&#39;s rank is <code>&quot;Gold Medal&quot;</code>.</li>
-	<li>The <code>2<sup>nd</sup></code> place athlete&#39;s rank is <code>&quot;Silver Medal&quot;</code>.</li>
-	<li>The <code>3<sup>rd</sup></code> place athlete&#39;s rank is <code>&quot;Bronze Medal&quot;</code>.</li>
-	<li>For the <code>4<sup>th</sup></code> place to the <code>n<sup>th</sup></code> place athlete, their rank is their placement number (i.e., the <code>x<sup>th</sup></code> place athlete&#39;s rank is <code>&quot;x&quot;</code>).</li>
-</ul>
-
-<p>Return an array <code>answer</code> of size <code>n</code> where <code>answer[i]</code> is the <strong>rank</strong> of the <code>i<sup>th</sup></code> athlete.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> score = [5,4,3,2,1]
-<strong>Output:</strong> [&quot;Gold Medal&quot;,&quot;Silver Medal&quot;,&quot;Bronze Medal&quot;,&quot;4&quot;,&quot;5&quot;]
-<strong>Explanation:</strong> The placements are [1<sup>st</sup>, 2<sup>nd</sup>, 3<sup>rd</sup>, 4<sup>th</sup>, 5<sup>th</sup>].</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> score = [10,3,8,9,4]
-<strong>Output:</strong> [&quot;Gold Medal&quot;,&quot;5&quot;,&quot;Bronze Medal&quot;,&quot;Silver Medal&quot;,&quot;4&quot;]
-<strong>Explanation:</strong> The placements are [1<sup>st</sup>, 5<sup>th</sup>, 3<sup>rd</sup>, 2<sup>nd</sup>, 4<sup>th</sup>].
-
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == score.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= score[i] &lt;= 10<sup>6</sup></code></li>
-	<li>All the values in <code>score</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
diff --git a/problems/relative-ranks/relative_ranks.go b/problems/relative-ranks/relative_ranks.go
deleted file mode 100644
index 522a67eeb..000000000
--- a/problems/relative-ranks/relative_ranks.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem506
diff --git a/problems/relative-ranks/relative_ranks_test.go b/problems/relative-ranks/relative_ranks_test.go
deleted file mode 100644
index 522a67eeb..000000000
--- a/problems/relative-ranks/relative_ranks_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem506
diff --git a/problems/relative-sort-array/README.md b/problems/relative-sort-array/README.md
deleted file mode 100644
index fec67f6ce..000000000
--- a/problems/relative-sort-array/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../divide-array-into-increasing-sequences "Divide Array Into Increasing Sequences")
-　　　　　　　　　　　　　　　　
-[Next >](../lowest-common-ancestor-of-deepest-leaves "Lowest Common Ancestor of Deepest Leaves")
-
-## [1122. Relative Sort Array (Easy)](https://leetcode.com/problems/relative-sort-array "数组的相对排序")
-
-<p>Given two arrays <code>arr1</code> and <code>arr2</code>, the elements of <code>arr2</code> are distinct, and all elements in <code>arr2</code> are also in <code>arr1</code>.</p>
-
-<p>Sort the elements of <code>arr1</code> such that the relative ordering of items in <code>arr1</code> are the same as in <code>arr2</code>. Elements that do not appear in <code>arr2</code> should be placed at the end of <code>arr1</code> in <strong>ascending</strong> order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [2,3,1,3,2,4,6,7,9,2,19], arr2 = [2,1,4,3,9,6]
-<strong>Output:</strong> [2,2,2,1,4,3,3,9,6,7,19]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr1 = [28,6,22,8,44,17], arr2 = [22,28,8,6]
-<strong>Output:</strong> [22,28,8,6,17,44]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr1.length, arr2.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= arr1[i], arr2[i] &lt;= 1000</code></li>
-	<li>All the elements of <code>arr2</code> are <strong>distinct</strong>.</li>
-	<li>Each&nbsp;<code>arr2[i]</code> is in <code>arr1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting Sort](../../tag/counting-sort/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Using a hashmap, we can map the values of arr2 to their position in arr2.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After, we can use a custom sorting function.
-</details>
diff --git a/problems/relative-sort-array/relative_sort_array.go b/problems/relative-sort-array/relative_sort_array.go
deleted file mode 100644
index 0cb3ee66c..000000000
--- a/problems/relative-sort-array/relative_sort_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1122
diff --git a/problems/remove-9/README.md b/problems/remove-9/README.md
deleted file mode 100644
index c186217f6..000000000
--- a/problems/remove-9/README.md
+++ /dev/null
@@ -1,31 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-array-into-consecutive-subsequences "Split Array into Consecutive Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../image-smoother "Image Smoother")
-
-## [660. Remove 9 (Hard)](https://leetcode.com/problems/remove-9 "移除 9")
-
-<p>Start from integer 1, remove any integer that contains 9 such as 9, 19, 29... </p>
-
-<p>So now, you will have a new integer sequence: 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, ...</p>
-
-<p>Given a positive integer <code>n</code>, you need to return the n-th integer after removing. Note that 1 will be the first integer.</p>
-
-<p><b>Example 1:</b><br />
-<pre><b>Input:</b> 9
-<b>Output:</b> 10
-</pre>
-</p>
-
-<p>
-<b> Hint</b>: n will not exceed <code>9 x 10^8</code>.
-</p>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/remove-9/remove_9.go b/problems/remove-9/remove_9.go
deleted file mode 100644
index 11da98995..000000000
--- a/problems/remove-9/remove_9.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem660
diff --git a/problems/remove-9/remove_9_test.go b/problems/remove-9/remove_9_test.go
deleted file mode 100644
index 11da98995..000000000
--- a/problems/remove-9/remove_9_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem660
diff --git a/problems/remove-all-adjacent-duplicates-in-string-ii/README.md b/problems/remove-all-adjacent-duplicates-in-string-ii/README.md
deleted file mode 100644
index cafcb86af..000000000
--- a/problems/remove-all-adjacent-duplicates-in-string-ii/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../get-equal-substrings-within-budget "Get Equal Substrings Within Budget")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-moves-to-reach-target-with-rotations "Minimum Moves to Reach Target with Rotations")
-
-## [1209. Remove All Adjacent Duplicates in String II (Medium)](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string-ii "删除字符串中的所有相邻重复项 II")
-
-<p>You are given a string <code>s</code> and an integer <code>k</code>, a <code>k</code> <strong>duplicate removal</strong> consists of choosing <code>k</code> adjacent and equal letters from <code>s</code> and removing them, causing the left and the right side of the deleted substring to concatenate together.</p>
-
-<p>We repeatedly make <code>k</code> <strong>duplicate removals</strong> on <code>s</code> until we no longer can.</p>
-
-<p>Return the final string after all such duplicate removals have been made. It is guaranteed that the answer is unique.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcd&quot;, k = 2
-<strong>Output:</strong> &quot;abcd&quot;
-<strong>Explanation: </strong>There&#39;s nothing to delete.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;deeedbbcccbdaa&quot;, k = 3
-<strong>Output:</strong> &quot;aa&quot;
-<strong>Explanation: 
-</strong>First delete &quot;eee&quot; and &quot;ccc&quot;, get &quot;ddbbbdaa&quot;
-Then delete &quot;bbb&quot;, get &quot;dddaa&quot;
-Finally delete &quot;ddd&quot;, get &quot;aa&quot;</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;pbbcggttciiippooaais&quot;, k = 2
-<strong>Output:</strong> &quot;ps&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>2 &lt;= k &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> only contains lower case English letters.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a stack to store the characters, when there are k same characters, delete them.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To make it more efficient, use a pair to store the value and the count of each character.
-</details>
diff --git a/problems/remove-all-adjacent-duplicates-in-string/README.md b/problems/remove-all-adjacent-duplicates-in-string/README.md
deleted file mode 100644
index 47d5e9e54..000000000
--- a/problems/remove-all-adjacent-duplicates-in-string/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../last-stone-weight "Last Stone Weight")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-string-chain "Longest String Chain")
-
-## [1047. Remove All Adjacent Duplicates In String (Easy)](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string "删除字符串中的所有相邻重复项")
-
-<p>You are given a string <code>s</code> consisting of lowercase English letters. A <strong>duplicate removal</strong> consists of choosing two <strong>adjacent</strong> and <strong>equal</strong> letters and removing them.</p>
-
-<p>We repeatedly make <strong>duplicate removals</strong> on <code>s</code> until we no longer can.</p>
-
-<p>Return <em>the final string after all such duplicate removals have been made</em>. It can be proven that the answer is <strong>unique</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abbaca&quot;
-<strong>Output:</strong> &quot;ca&quot;
-<strong>Explanation:</strong> 
-For example, in &quot;abbaca&quot; we could remove &quot;bb&quot; since the letters are adjacent and equal, and this is the only possible move.  The result of this move is that the string is &quot;aaca&quot;, of which only &quot;aa&quot; is possible, so the final string is &quot;ca&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;azxxzy&quot;
-<strong>Output:</strong> &quot;ay&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a stack to process everything greedily.
-</details>
diff --git a/problems/remove-all-adjacent-duplicates-in-string/remove_all_adjacent_duplicates_in_string.go b/problems/remove-all-adjacent-duplicates-in-string/remove_all_adjacent_duplicates_in_string.go
deleted file mode 100644
index fc316bbbb..000000000
--- a/problems/remove-all-adjacent-duplicates-in-string/remove_all_adjacent_duplicates_in_string.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem1047
-
-func removeDuplicates(S string) string {
-	ans := make([]byte, 0, len(S))
-	for i := 0; i < len(S); i++ {
-		n := len(ans) - 1
-		if n >= 0 && ans[n] == S[i] {
-			ans = ans[:n]
-		} else {
-			ans = append(ans, S[i])
-		}
-	}
-	return string(ans)
-}
diff --git a/problems/remove-all-adjacent-duplicates-in-string/remove_all_adjacent_duplicates_in_string_test.go b/problems/remove-all-adjacent-duplicates-in-string/remove_all_adjacent_duplicates_in_string_test.go
deleted file mode 100644
index 5ba27ce9d..000000000
--- a/problems/remove-all-adjacent-duplicates-in-string/remove_all_adjacent_duplicates_in_string_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem1047
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestRemoveDuplicates(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "abbaca",
-			want: "ca",
-		},
-		{
-			in:   "aaabaca",
-			want: "abaca",
-		},
-	}
-	for _, tt := range tests {
-		got := removeDuplicates(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/remove-all-occurrences-of-a-substring/README.md b/problems/remove-all-occurrences-of-a-substring/README.md
deleted file mode 100644
index f73fbe00d..000000000
--- a/problems/remove-all-occurrences-of-a-substring/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-one-element-to-make-the-array-strictly-increasing "Remove One Element to Make the Array Strictly Increasing")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-alternating-subsequence-sum "Maximum Alternating Subsequence Sum")
-
-## [1910. Remove All Occurrences of a Substring (Medium)](https://leetcode.com/problems/remove-all-occurrences-of-a-substring "删除一个字符串中所有出现的给定子字符串")
-
-<p>Given two strings <code>s</code> and <code>part</code>, perform the following operation on <code>s</code> until <strong>all</strong> occurrences of the substring <code>part</code> are removed:</p>
-
-<ul>
-	<li>Find the <strong>leftmost</strong> occurrence of the substring <code>part</code> and <strong>remove</strong> it from <code>s</code>.</li>
-</ul>
-
-<p>Return <code>s</code><em> after removing all occurrences of </em><code>part</code>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters in a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;daabcbaabcbc&quot;, part = &quot;abc&quot;
-<strong>Output:</strong> &quot;dab&quot;
-<strong>Explanation</strong>: The following operations are done:
-- s = &quot;da<strong><u>abc</u></strong>baabcbc&quot;, remove &quot;abc&quot; starting at index 2, so s = &quot;dabaabcbc&quot;.
-- s = &quot;daba<strong><u>abc</u></strong>bc&quot;, remove &quot;abc&quot; starting at index 4, so s = &quot;dababc&quot;.
-- s = &quot;dab<strong><u>abc</u></strong>&quot;, remove &quot;abc&quot; starting at index 3, so s = &quot;dab&quot;.
-Now s has no occurrences of &quot;abc&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;axxxxyyyyb&quot;, part = &quot;xy&quot;
-<strong>Output:</strong> &quot;ab&quot;
-<strong>Explanation</strong>: The following operations are done:
-- s = &quot;axxx<strong><u>xy</u></strong>yyyb&quot;, remove &quot;xy&quot; starting at index 4 so s = &quot;axxxyyyb&quot;.
-- s = &quot;axx<strong><u>xy</u></strong>yyb&quot;, remove &quot;xy&quot; starting at index 3 so s = &quot;axxyyb&quot;.
-- s = &quot;ax<strong><u>xy</u></strong>yb&quot;, remove &quot;xy&quot; starting at index 2 so s = &quot;axyb&quot;.
-- s = &quot;a<strong><u>xy</u></strong>b&quot;, remove &quot;xy&quot; starting at index 1 so s = &quot;ab&quot;.
-Now s has no occurrences of &quot;xy&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= part.length &lt;= 1000</code></li>
-	<li><code>s</code>​​​​​​ and <code>part</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that a new occurrence of pattern can appear if you remove an old one, For example, s = "ababcc" and pattern = "abc".
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can maintain a stack of characters and if the last character of the pattern size in the stack match the pattern remove them
-</details>
diff --git a/problems/remove-all-ones-with-row-and-column-flips/README.md b/problems/remove-all-ones-with-row-and-column-flips/README.md
deleted file mode 100644
index f1857a910..000000000
--- a/problems/remove-all-ones-with-row-and-column-flips/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-employees-to-be-invited-to-a-meeting "Maximum Employees to Be Invited to a Meeting")
-　　　　　　　　　　　　　　　　
-[Next >](../capitalize-the-title "Capitalize the Title")
-
-## [2128. Remove All Ones With Row and Column Flips (Medium)](https://leetcode.com/problems/remove-all-ones-with-row-and-column-flips "")
-
-
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Does the order, in which you do the operations, matter?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-No, it does not. An element will keep its original value if the number of operations done on it is even and vice versa. This also means that doing more than 1 operation on the same row or column is unproductive.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Try working backward, start with a matrix of all zeros and try to construct grid using operations.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Start with operations on columns, after doing them what do you notice about each row?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Each row is the exact same. If we then flip some rows, that leaves only two possible arrangements for each row: the same as the original or the opposite.
-</details>
diff --git a/problems/remove-boxes/README.md b/problems/remove-boxes/README.md
deleted file mode 100644
index 30282b6d7..000000000
--- a/problems/remove-boxes/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../boundary-of-binary-tree "Boundary of Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-provinces "Number of Provinces")
-
-## [546. Remove Boxes (Hard)](https://leetcode.com/problems/remove-boxes "移除盒子")
-
-<p>You are given several <code>boxes</code> with different colors represented by different positive numbers.</p>
-
-<p>You may experience several rounds to remove boxes until there is no box left. Each time you can choose some continuous boxes with the same color (i.e., composed of <code>k</code> boxes, <code>k &gt;= 1</code>), remove them and get <code>k * k</code> points.</p>
-
-<p>Return <em>the maximum points you can get</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxes = [1,3,2,2,2,3,4,3,1]
-<strong>Output:</strong> 23
-<strong>Explanation:</strong>
-[1, 3, 2, 2, 2, 3, 4, 3, 1] 
-----&gt; [1, 3, 3, 4, 3, 1] (3*3=9 points) 
-----&gt; [1, 3, 3, 3, 1] (1*1=1 points) 
-----&gt; [1, 1] (3*3=9 points) 
-----&gt; [] (2*2=4 points)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxes = [1,1,1]
-<strong>Output:</strong> 9
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> boxes = [1]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= boxes.length &lt;= 100</code></li>
-	<li><code>1 &lt;= boxes[i]&nbsp;&lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-
-### Similar Questions
-  1. [Strange Printer](../strange-printer) (Hard)
diff --git a/problems/remove-boxes/remove_boxes.go b/problems/remove-boxes/remove_boxes.go
deleted file mode 100644
index d42b0a8c0..000000000
--- a/problems/remove-boxes/remove_boxes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem546
diff --git a/problems/remove-boxes/remove_boxes_test.go b/problems/remove-boxes/remove_boxes_test.go
deleted file mode 100644
index d42b0a8c0..000000000
--- a/problems/remove-boxes/remove_boxes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem546
diff --git a/problems/remove-colored-pieces-if-both-neighbors-are-the-same-color/README.md b/problems/remove-colored-pieces-if-both-neighbors-are-the-same-color/README.md
deleted file mode 100644
index c8b5cd729..000000000
--- a/problems/remove-colored-pieces-if-both-neighbors-are-the-same-color/README.md
+++ /dev/null
@@ -1,100 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-moves-to-seat-everyone "Minimum Number of Moves to Seat Everyone")
-　　　　　　　　　　　　　　　　
-[Next >](../the-time-when-the-network-becomes-idle "The Time When the Network Becomes Idle")
-
-## [2038. Remove Colored Pieces if Both Neighbors are the Same Color (Medium)](https://leetcode.com/problems/remove-colored-pieces-if-both-neighbors-are-the-same-color "如果相邻两个颜色均相同则删除当前颜色")
-
-<p>There are <code>n</code> pieces arranged in a line, and each piece is colored either by <code>&#39;A&#39;</code> or by <code>&#39;B&#39;</code>. You are given a string <code>colors</code> of length <code>n</code> where <code>colors[i]</code> is the color of the <code>i<sup>th</sup></code> piece.</p>
-
-<p>Alice and Bob are playing a game where they take <strong>alternating turns</strong> removing pieces from the line. In this game, Alice moves<strong> first</strong>.</p>
-
-<ul>
-	<li>Alice is only allowed to remove a piece colored <code>&#39;A&#39;</code> if <strong>both its neighbors</strong> are also colored <code>&#39;A&#39;</code>. She is <strong>not allowed</strong> to remove pieces that are colored <code>&#39;B&#39;</code>.</li>
-	<li>Bob is only allowed to remove a piece colored <code>&#39;B&#39;</code> if <strong>both its neighbors</strong> are also colored <code>&#39;B&#39;</code>. He is <strong>not allowed</strong> to remove pieces that are colored <code>&#39;A&#39;</code>.</li>
-	<li>Alice and Bob <strong>cannot</strong> remove pieces from the edge of the line.</li>
-	<li>If a player cannot make a move on their turn, that player <strong>loses</strong> and the other player <strong>wins</strong>.</li>
-</ul>
-
-<p>Assuming Alice and Bob play optimally, return <code>true</code><em> if Alice wins, or return </em><code>false</code><em> if Bob wins</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> colors = &quot;AAABABB&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-A<u>A</u>ABABB -&gt; AABABB
-Alice moves first.
-She removes the second &#39;A&#39; from the left since that is the only &#39;A&#39; whose neighbors are both &#39;A&#39;.
-
-Now it&#39;s Bob&#39;s turn.
-Bob cannot make a move on his turn since there are no &#39;B&#39;s whose neighbors are both &#39;B&#39;.
-Thus, Alice wins, so return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> colors = &quot;AA&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-Alice has her turn first.
-There are only two &#39;A&#39;s and both are on the edge of the line, so she cannot move on her turn.
-Thus, Bob wins, so return false.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> colors = &quot;ABBBBBBBAAA&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-ABBBBBBBA<u>A</u>A -&gt; ABBBBBBBAA
-Alice moves first.
-Her only option is to remove the second to last &#39;A&#39; from the right.
-
-ABBBB<u>B</u>BBAA -&gt; ABBBBBBAA
-Next is Bob&#39;s turn.
-He has many options for which &#39;B&#39; piece to remove. He can pick any.
-
-On Alice&#39;s second turn, she has no more pieces that she can remove.
-Thus, Bob wins, so return false.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;colors.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>colors</code>&nbsp;consists of only the letters&nbsp;<code>&#39;A&#39;</code>&nbsp;and&nbsp;<code>&#39;B&#39;</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Does the number of moves a player can make depend on what the other player does? No
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How many moves can Alice make if colors == "AAAAAA"
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If a group of n consecutive pieces has the same color, the player can take n - 2 of those pieces if n is greater than or equal to 3
-</details>
diff --git a/problems/remove-comments/README.md b/problems/remove-comments/README.md
deleted file mode 100644
index 49f4c74c0..000000000
--- a/problems/remove-comments/README.md
+++ /dev/null
@@ -1,115 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../accounts-merge "Accounts Merge")
-　　　　　　　　　　　　　　　　
-[Next >](../candy-crush "Candy Crush")
-
-## [722. Remove Comments (Medium)](https://leetcode.com/problems/remove-comments "删除注释")
-
-<p>Given a C++ program, remove comments from it. The program source is an array of strings <code>source</code> where <code>source[i]</code> is the <code>i<sup>th</sup></code> line of the source code. This represents the result of splitting the original source code string by the newline character <code>&#39;\n&#39;</code>.</p>
-
-<p>In C++, there are two types of comments, line comments, and block comments.</p>
-
-<ul>
-	<li>The string <code>&quot;//&quot;</code> denotes a line comment, which represents that it and the rest of the characters to the right of it in the same line should be ignored.</li>
-	<li>The string <code>&quot;/*&quot;</code> denotes a block comment, which represents that all characters until the next (non-overlapping) occurrence of <code>&quot;*/&quot;</code> should be ignored. (Here, occurrences happen in reading order: line by line from left to right.) To be clear, the string <code>&quot;/*/&quot;</code> does not yet end the block comment, as the ending would be overlapping the beginning.</li>
-</ul>
-
-<p>The first effective comment takes precedence over others.</p>
-
-<ul>
-	<li>For example, if the string <code>&quot;//&quot;</code> occurs in a block comment, it is ignored.</li>
-	<li>Similarly, if the string <code>&quot;/*&quot;</code> occurs in a line or block comment, it is also ignored.</li>
-</ul>
-
-<p>If a certain line of code is empty after removing comments, you must not output that line: each string in the answer list will be non-empty.</p>
-
-<p>There will be no control characters, single quote, or double quote characters.</p>
-
-<ul>
-	<li>For example, <code>source = &quot;string s = &quot;/* Not a comment. */&quot;;&quot;</code> will not be a test case.</li>
-</ul>
-
-<p>Also, nothing else such as defines or macros will interfere with the comments.</p>
-
-<p>It is guaranteed that every open block comment will eventually be closed, so <code>&quot;/*&quot;</code> outside of a line or block comment always starts a new comment.</p>
-
-<p>Finally, implicit newline characters can be deleted by block comments. Please see the examples below for details.</p>
-
-<p>After removing the comments from the source code, return <em>the source code in the same format</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> source = [&quot;/*Test program */&quot;, &quot;int main()&quot;, &quot;{ &quot;, &quot;  // variable declaration &quot;, &quot;int a, b, c;&quot;, &quot;/* This is a test&quot;, &quot;   multiline  &quot;, &quot;   comment for &quot;, &quot;   testing */&quot;, &quot;a = b + c;&quot;, &quot;}&quot;]
-<strong>Output:</strong> [&quot;int main()&quot;,&quot;{ &quot;,&quot;  &quot;,&quot;int a, b, c;&quot;,&quot;a = b + c;&quot;,&quot;}&quot;]
-<strong>Explanation:</strong> The line by line code is visualized as below:
-/*Test program */
-int main()
-{ 
-  // variable declaration 
-int a, b, c;
-/* This is a test
-   multiline  
-   comment for 
-   testing */
-a = b + c;
-}
-The string /* denotes a block comment, including line 1 and lines 6-9. The string // denotes line 4 as comments.
-The line by line output code is visualized as below:
-int main()
-{ 
-  
-int a, b, c;
-a = b + c;
-}
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> source = [&quot;a/*comment&quot;, &quot;line&quot;, &quot;more_comment*/b&quot;]
-<strong>Output:</strong> [&quot;ab&quot;]
-<strong>Explanation:</strong> The original source string is &quot;a/*comment\nline\nmore_comment*/b&quot;, where we have bolded the newline characters.  After deletion, the implicit newline characters are deleted, leaving the string &quot;ab&quot;, which when delimited by newline characters becomes [&quot;ab&quot;].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= source.length &lt;= 100</code></li>
-	<li><code>0 &lt;= source[i].length &lt;= 80</code></li>
-	<li><code>source[i]</code> consists of printable <strong>ASCII</strong> characters.</li>
-	<li>Every open block comment is eventually closed.</li>
-	<li>There are no single-quote or&nbsp;double-quote in the input.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Mini Parser](../mini-parser) (Medium)
-  1. [Ternary Expression Parser](../ternary-expression-parser) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Carefully parse each line according to the following rules:
-
-* If we start a block comment and we aren't in a block, then we will skip over the next two characters and change our state to be in a block.
-
-* If we end a block comment and we are in a block, then we will skip over the next two characters and change our state to be *not* in a block.
-
-* If we start a line comment and we aren't in a block, then we will ignore the rest of the line.
-
-* If we aren't in a block comment (and it wasn't the start of a comment), we will record the character we are at.
-
-* At the end of each line, if we aren't in a block, we will record the line.
-</details>
diff --git a/problems/remove-comments/remove_comments.go b/problems/remove-comments/remove_comments.go
deleted file mode 100644
index b58fe61e2..000000000
--- a/problems/remove-comments/remove_comments.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem722
diff --git a/problems/remove-comments/remove_comments_test.go b/problems/remove-comments/remove_comments_test.go
deleted file mode 100644
index b58fe61e2..000000000
--- a/problems/remove-comments/remove_comments_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem722
diff --git a/problems/remove-covered-intervals/README.md b/problems/remove-covered-intervals/README.md
deleted file mode 100644
index 22a2a0ad3..000000000
--- a/problems/remove-covered-intervals/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../element-appearing-more-than-25-in-sorted-array "Element Appearing More Than 25% In Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-falling-path-sum-ii "Minimum Falling Path Sum II")
-
-## [1288. Remove Covered Intervals (Medium)](https://leetcode.com/problems/remove-covered-intervals "删除被覆盖区间")
-
-<p>Given an array <code>intervals</code> where <code>intervals[i] = [l<sub>i</sub>, r<sub>i</sub>]</code> represent the interval <code>[l<sub>i</sub>, r<sub>i</sub>)</code>, remove all intervals that are covered by another interval in the list.</p>
-
-<p>The interval <code>[a, b)</code> is covered by the interval <code>[c, d)</code> if and only if <code>c &lt;= a</code> and <code>b &lt;= d</code>.</p>
-
-<p>Return <em>the number of remaining intervals</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,4],[3,6],[2,8]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Interval [3,6] is covered by [2,8], therefore it is removed.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,4],[2,3]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= intervals.length &lt;= 1000</code></li>
-	<li><code>intervals[i].length == 2</code></li>
-	<li><code>0 &lt;= l<sub>i</sub> &lt;= r<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-	<li>All the given intervals are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to check if an interval is covered by another?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Compare each interval to all others and check if it is covered by any interval.
-</details>
diff --git a/problems/remove-duplicate-letters/README.md b/problems/remove-duplicate-letters/README.md
deleted file mode 100644
index e61c74e31..000000000
--- a/problems/remove-duplicate-letters/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-of-smaller-numbers-after-self "Count of Smaller Numbers After Self")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-distance-from-all-buildings "Shortest Distance from All Buildings")
-
-## [316. Remove Duplicate Letters (Medium)](https://leetcode.com/problems/remove-duplicate-letters "去除重复字母")
-
-<p>Given a string <code>s</code>, remove duplicate letters so that every letter appears once and only once. You must make sure your result is <strong>the smallest in lexicographical order</strong> among all possible results.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bcabc&quot;
-<strong>Output:</strong> &quot;abc&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cbacdcbc&quot;
-<strong>Output:</strong> &quot;acdb&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 1081: <a href="https://leetcode.com/problems/smallest-subsequence-of-distinct-characters/" target="_blank">https://leetcode.com/problems/smallest-subsequence-of-distinct-characters/</a></p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Greedily try to add one missing character. How to check if adding some character will not cause problems ? Use bit-masks to check whether you will be able to complete the sub-sequence if you add the character at some index i.
-</details>
diff --git a/problems/remove-duplicate-letters/remove_duplicate_letters.go b/problems/remove-duplicate-letters/remove_duplicate_letters.go
deleted file mode 100644
index 2a0584d9e..000000000
--- a/problems/remove-duplicate-letters/remove_duplicate_letters.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem316
diff --git a/problems/remove-duplicate-letters/remove_duplicate_letters_test.go b/problems/remove-duplicate-letters/remove_duplicate_letters_test.go
deleted file mode 100644
index 2a0584d9e..000000000
--- a/problems/remove-duplicate-letters/remove_duplicate_letters_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem316
diff --git a/problems/remove-duplicates-from-an-unsorted-linked-list/README.md b/problems/remove-duplicates-from-an-unsorted-linked-list/README.md
deleted file mode 100644
index 27ee4a822..000000000
--- a/problems/remove-duplicates-from-an-unsorted-linked-list/README.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-xor-sum-of-all-pairs-bitwise-and "Find XOR Sum of All Pairs Bitwise AND")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-digits-in-base-k "Sum of Digits in Base K")
-
-## [1836. Remove Duplicates From an Unsorted Linked List (Medium)](https://leetcode.com/problems/remove-duplicates-from-an-unsorted-linked-list "从未排序的链表中移除重复元素")
-
-
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is there a way we can know beforehand which nodes to delete?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Count the number of appearances for each number.
-</details>
diff --git a/problems/remove-duplicates-from-sorted-array-ii/README.md b/problems/remove-duplicates-from-sorted-array-ii/README.md
deleted file mode 100644
index 8d14937d8..000000000
--- a/problems/remove-duplicates-from-sorted-array-ii/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-search "Word Search")
-　　　　　　　　　　　　　　　　
-[Next >](../search-in-rotated-sorted-array-ii "Search in Rotated Sorted Array II")
-
-## [80. Remove Duplicates from Sorted Array II (Medium)](https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii "删除有序数组中的重复项 II")
-
-<p>Given an integer array <code>nums</code> sorted in <strong>non-decreasing order</strong>, remove some duplicates <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank"><strong>in-place</strong></a> such that each unique element appears <strong>at most twice</strong>. The <strong>relative order</strong> of the elements should be kept the <strong>same</strong>.</p>
-
-<p>Since it is impossible to change the length of the array in some languages, you must instead have the result be placed in the <strong>first part</strong> of the array <code>nums</code>. More formally, if there are <code>k</code> elements after removing the duplicates, then the first <code>k</code> elements of <code>nums</code>&nbsp;should hold the final result. It does not matter what you leave beyond the first&nbsp;<code>k</code>&nbsp;elements.</p>
-
-<p>Return <code>k</code><em> after placing the final result in the first </em><code>k</code><em> slots of </em><code>nums</code>.</p>
-
-<p>Do <strong>not</strong> allocate extra space for another array. You must do this by <strong>modifying the input array <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank">in-place</a></strong> with O(1) extra memory.</p>
-
-<p><strong>Custom Judge:</strong></p>
-
-<p>The judge will test your solution with the following code:</p>
-
-<pre>
-int[] nums = [...]; // Input array
-int[] expectedNums = [...]; // The expected answer with correct length
-
-int k = removeDuplicates(nums); // Calls your implementation
-
-assert k == expectedNums.length;
-for (int i = 0; i &lt; k; i++) {
-    assert nums[i] == expectedNums[i];
-}
-</pre>
-
-<p>If all assertions pass, then your solution will be <strong>accepted</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,2,2,3]
-<strong>Output:</strong> 5, nums = [1,1,2,2,3,_]
-<strong>Explanation:</strong> Your function should return k = 5, with the first five elements of nums being 1, 1, 2, 2 and 3 respectively.
-It does not matter what you leave beyond the returned k (hence they are underscores).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,1,1,1,1,2,3,3]
-<strong>Output:</strong> 7, nums = [0,0,1,1,2,3,3,_,_]
-<strong>Explanation:</strong> Your function should return k = 7, with the first seven elements of nums being 0, 0, 1, 1, 2, 3 and 3 respectively.
-It does not matter what you leave beyond the returned k (hence they are underscores).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>nums</code> is sorted in <strong>non-decreasing</strong> order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Remove Duplicates from Sorted Array](../remove-duplicates-from-sorted-array) (Easy)
diff --git a/problems/remove-duplicates-from-sorted-array-ii/remove_duplicates_from_sorted_array_ii.go b/problems/remove-duplicates-from-sorted-array-ii/remove_duplicates_from_sorted_array_ii.go
deleted file mode 100644
index 9470ffd79..000000000
--- a/problems/remove-duplicates-from-sorted-array-ii/remove_duplicates_from_sorted_array_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem80
diff --git a/problems/remove-duplicates-from-sorted-array-ii/remove_duplicates_from_sorted_array_ii_test.go b/problems/remove-duplicates-from-sorted-array-ii/remove_duplicates_from_sorted_array_ii_test.go
deleted file mode 100644
index 9470ffd79..000000000
--- a/problems/remove-duplicates-from-sorted-array-ii/remove_duplicates_from_sorted_array_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem80
diff --git a/problems/remove-duplicates-from-sorted-array/README.md b/problems/remove-duplicates-from-sorted-array/README.md
deleted file mode 100644
index 293709445..000000000
--- a/problems/remove-duplicates-from-sorted-array/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-nodes-in-k-group "Reverse Nodes in k-Group")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-element "Remove Element")
-
-## [26. Remove Duplicates from Sorted Array (Easy)](https://leetcode.com/problems/remove-duplicates-from-sorted-array "删除有序数组中的重复项")
-
-<p>Given an integer array <code>nums</code> sorted in <strong>non-decreasing order</strong>, remove the duplicates <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank"><strong>in-place</strong></a> such that each unique element appears only <strong>once</strong>. The <strong>relative order</strong> of the elements should be kept the <strong>same</strong>.</p>
-
-<p>Since it is impossible to change the length of the array in some languages, you must instead have the result be placed in the <strong>first part</strong> of the array <code>nums</code>. More formally, if there are <code>k</code> elements after removing the duplicates, then the first <code>k</code> elements of <code>nums</code>&nbsp;should hold the final result. It does not matter what you leave beyond the first&nbsp;<code>k</code>&nbsp;elements.</p>
-
-<p>Return <code>k</code><em> after placing the final result in the first </em><code>k</code><em> slots of </em><code>nums</code>.</p>
-
-<p>Do <strong>not</strong> allocate extra space for another array. You must do this by <strong>modifying the input array <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank">in-place</a></strong> with O(1) extra memory.</p>
-
-<p><strong>Custom Judge:</strong></p>
-
-<p>The judge will test your solution with the following code:</p>
-
-<pre>
-int[] nums = [...]; // Input array
-int[] expectedNums = [...]; // The expected answer with correct length
-
-int k = removeDuplicates(nums); // Calls your implementation
-
-assert k == expectedNums.length;
-for (int i = 0; i &lt; k; i++) {
-    assert nums[i] == expectedNums[i];
-}
-</pre>
-
-<p>If all assertions pass, then your solution will be <strong>accepted</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,2]
-<strong>Output:</strong> 2, nums = [1,2,_]
-<strong>Explanation:</strong> Your function should return k = 2, with the first two elements of nums being 1 and 2 respectively.
-It does not matter what you leave beyond the returned k (hence they are underscores).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,1,1,1,2,2,3,3,4]
-<strong>Output:</strong> 5, nums = [0,1,2,3,4,_,_,_,_,_]
-<strong>Explanation:</strong> Your function should return k = 5, with the first five elements of nums being 0, 1, 2, 3, and 4 respectively.
-It does not matter what you leave beyond the returned k (hence they are underscores).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
-	<li><code>nums</code> is sorted in <strong>non-decreasing</strong> order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Remove Element](../remove-element) (Easy)
-  1. [Remove Duplicates from Sorted Array II](../remove-duplicates-from-sorted-array-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-In this problem, the key point to focus on is the input array being sorted. As far as duplicate elements are concerned, what is their positioning in the array when the given array is sorted? Look at the image above for the answer. If we know the position of one of the elements, do we also know the positioning of all the duplicate elements?
-
-<br>
-<img src="https://assets.leetcode.com/uploads/2019/10/20/hint_rem_dup.png" width="500"/>
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We need to modify the array in-place and the size of the final array would potentially be smaller than the size of the input array. So, we ought to use a two-pointer approach here. One, that would keep track of the current element in the original array and another one for just the unique elements.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Essentially, once an element is encountered, you simply need to <b>bypass</b> its duplicates and move on to the next unique element.
-</details>
diff --git a/problems/remove-duplicates-from-sorted-array/remove_duplicates_from_sorted_array.go b/problems/remove-duplicates-from-sorted-array/remove_duplicates_from_sorted_array.go
deleted file mode 100644
index 8e56b5d11..000000000
--- a/problems/remove-duplicates-from-sorted-array/remove_duplicates_from_sorted_array.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem26
-
-func removeDuplicates(nums []int) int {
-	top, l := 0, len(nums)
-	if l == 0 {
-		return 0
-	}
-	for i := 1; i < l; i++ {
-		if nums[i] != nums[top] {
-			top++
-			nums[top] = nums[i]
-		}
-	}
-	return top + 1
-}
diff --git a/problems/remove-duplicates-from-sorted-array/remove_duplicates_from_sorted_array_test.go b/problems/remove-duplicates-from-sorted-array/remove_duplicates_from_sorted_array_test.go
deleted file mode 100644
index 5680e875a..000000000
--- a/problems/remove-duplicates-from-sorted-array/remove_duplicates_from_sorted_array_test.go
+++ /dev/null
@@ -1,46 +0,0 @@
-package problem26
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestRemoveDuplicates(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 1, 2},
-			want: []int{1, 2},
-		},
-		{
-			in:   []int{0, 0, 1, 1, 1, 2, 2, 3, 3, 4},
-			want: []int{0, 1, 2, 3, 4},
-		},
-		{
-			in:   []int{1, 2, 3, 4},
-			want: []int{1, 2, 3, 4},
-		},
-		{
-			in:   []int{1, 2, 2, 3, 3, 3, 4, 4, 4, 4},
-			want: []int{1, 2, 3, 4},
-		},
-		{
-			in:   []int{},
-			want: []int{},
-		},
-	}
-
-	for _, tt := range tests {
-		nums := make([]int, len(tt.in))
-		copy(nums, tt.in)
-		l := removeDuplicates(nums)
-		got := nums[:l]
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/remove-duplicates-from-sorted-list-ii/README.md b/problems/remove-duplicates-from-sorted-list-ii/README.md
deleted file mode 100644
index fb75f2c4c..000000000
--- a/problems/remove-duplicates-from-sorted-list-ii/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../search-in-rotated-sorted-array-ii "Search in Rotated Sorted Array II")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-duplicates-from-sorted-list "Remove Duplicates from Sorted List")
-
-## [82. Remove Duplicates from Sorted List II (Medium)](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii "删除排序链表中的重复元素 II")
-
-<p>Given the <code>head</code> of a sorted linked list, <em>delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list</em>. Return <em>the linked list <strong>sorted</strong> as well</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/linkedlist1.jpg" style="width: 500px; height: 142px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,3,4,4,5]
-<strong>Output:</strong> [1,2,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/linkedlist2.jpg" style="width: 500px; height: 205px;" />
-<pre>
-<strong>Input:</strong> head = [1,1,1,2,3]
-<strong>Output:</strong> [2,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[0, 300]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-	<li>The list is guaranteed to be <strong>sorted</strong> in ascending order.</li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Remove Duplicates from Sorted List](../remove-duplicates-from-sorted-list) (Easy)
diff --git a/problems/remove-duplicates-from-sorted-list-ii/remove_duplicates_from_sorted_list_ii.go b/problems/remove-duplicates-from-sorted-list-ii/remove_duplicates_from_sorted_list_ii.go
deleted file mode 100644
index a738caa57..000000000
--- a/problems/remove-duplicates-from-sorted-list-ii/remove_duplicates_from_sorted_list_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem82
diff --git a/problems/remove-duplicates-from-sorted-list-ii/remove_duplicates_from_sorted_list_ii_test.go b/problems/remove-duplicates-from-sorted-list-ii/remove_duplicates_from_sorted_list_ii_test.go
deleted file mode 100644
index a738caa57..000000000
--- a/problems/remove-duplicates-from-sorted-list-ii/remove_duplicates_from_sorted_list_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem82
diff --git a/problems/remove-duplicates-from-sorted-list/README.md b/problems/remove-duplicates-from-sorted-list/README.md
deleted file mode 100644
index 19e592c13..000000000
--- a/problems/remove-duplicates-from-sorted-list/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-duplicates-from-sorted-list-ii "Remove Duplicates from Sorted List II")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-rectangle-in-histogram "Largest Rectangle in Histogram")
-
-## [83. Remove Duplicates from Sorted List (Easy)](https://leetcode.com/problems/remove-duplicates-from-sorted-list "删除排序链表中的重复元素")
-
-<p>Given the <code>head</code> of a sorted linked list, <em>delete all duplicates such that each element appears only once</em>. Return <em>the linked list <strong>sorted</strong> as well</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/list1.jpg" style="width: 302px; height: 242px;" />
-<pre>
-<strong>Input:</strong> head = [1,1,2]
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/list2.jpg" style="width: 542px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,1,2,3,3]
-<strong>Output:</strong> [1,2,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[0, 300]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-	<li>The list is guaranteed to be <strong>sorted</strong> in ascending order.</li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Remove Duplicates from Sorted List II](../remove-duplicates-from-sorted-list-ii) (Medium)
diff --git a/problems/remove-duplicates-from-sorted-list/remove_duplicates_from_sorted_list.go b/problems/remove-duplicates-from-sorted-list/remove_duplicates_from_sorted_list.go
deleted file mode 100644
index 938b18944..000000000
--- a/problems/remove-duplicates-from-sorted-list/remove_duplicates_from_sorted_list.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package problem83
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func deleteDuplicates(head *ListNode) *ListNode {
-	for prev, t := head, head; t != nil; t = t.Next {
-		if prev.Val == t.Val {
-			prev.Next = t.Next
-		} else {
-			prev = t
-		}
-	}
-	return head
-}
diff --git a/problems/remove-duplicates-from-sorted-list/remove_duplicates_from_sorted_list_test.go b/problems/remove-duplicates-from-sorted-list/remove_duplicates_from_sorted_list_test.go
deleted file mode 100644
index 8c040aedc..000000000
--- a/problems/remove-duplicates-from-sorted-list/remove_duplicates_from_sorted_list_test.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package problem83
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestDeleteDuplicates(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 1, 2},
-			want: []int{1, 2},
-		},
-		{
-			in:   []int{1, 1, 2, 3, 3},
-			want: []int{1, 2, 3},
-		},
-		{
-			in:   []int{0, 0, 1, 1, 2, 2},
-			want: []int{0, 1, 2},
-		},
-	}
-	for _, tt := range tests {
-		got := deleteDuplicates(kit.SliceInt2ListNode(tt.in))
-		if !reflect.DeepEqual(kit.ListNode2SliceInt(got), tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/remove-element/README.md b/problems/remove-element/README.md
deleted file mode 100644
index 6a3a4c92d..000000000
--- a/problems/remove-element/README.md
+++ /dev/null
@@ -1,96 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-duplicates-from-sorted-array "Remove Duplicates from Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../implement-strstr "Implement strStr()")
-
-## [27. Remove Element (Easy)](https://leetcode.com/problems/remove-element "移除元素")
-
-<p>Given an integer array <code>nums</code> and an integer <code>val</code>, remove all occurrences of <code>val</code> in <code>nums</code> <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank"><strong>in-place</strong></a>. The relative order of the elements may be changed.</p>
-
-<p>Since it is impossible to change the length of the array in some languages, you must instead have the result be placed in the <strong>first part</strong> of the array <code>nums</code>. More formally, if there are <code>k</code> elements after removing the duplicates, then the first <code>k</code> elements of <code>nums</code> should hold the final result. It does not matter what you leave beyond the first <code>k</code> elements.</p>
-
-<p>Return <code>k</code><em> after placing the final result in the first </em><code>k</code><em> slots of </em><code>nums</code>.</p>
-
-<p>Do <strong>not</strong> allocate extra space for another array. You must do this by <strong>modifying the input array <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank">in-place</a></strong> with O(1) extra memory.</p>
-
-<p><strong>Custom Judge:</strong></p>
-
-<p>The judge will test your solution with the following code:</p>
-
-<pre>
-int[] nums = [...]; // Input array
-int val = ...; // Value to remove
-int[] expectedNums = [...]; // The expected answer with correct length.
-                            // It is sorted with no values equaling val.
-
-int k = removeElement(nums, val); // Calls your implementation
-
-assert k == expectedNums.length;
-sort(nums, 0, k); // Sort the first k elements of nums
-for (int i = 0; i &lt; actualLength; i++) {
-    assert nums[i] == expectedNums[i];
-}
-</pre>
-
-<p>If all assertions pass, then your solution will be <strong>accepted</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,2,3], val = 3
-<strong>Output:</strong> 2, nums = [2,2,_,_]
-<strong>Explanation:</strong> Your function should return k = 2, with the first two elements of nums being 2.
-It does not matter what you leave beyond the returned k (hence they are underscores).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,2,2,3,0,4,2], val = 2
-<strong>Output:</strong> 5, nums = [0,1,4,0,3,_,_,_]
-<strong>Explanation:</strong> Your function should return k = 5, with the first five elements of nums containing 0, 0, 1, 3, and 4.
-Note that the five elements can be returned in any order.
-It does not matter what you leave beyond the returned k (hence they are underscores).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 50</code></li>
-	<li><code>0 &lt;= val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Remove Duplicates from Sorted Array](../remove-duplicates-from-sorted-array) (Easy)
-  1. [Remove Linked List Elements](../remove-linked-list-elements) (Easy)
-  1. [Move Zeroes](../move-zeroes) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The problem statement clearly asks us to modify the array in-place and it also says that the element beyond the new length of the array can be anything. Given an element, we need to remove all the occurrences of it from the array. We don't technically need to <b>remove</b> that element per-say, right?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can move all the occurrences of this element to the end of the array. Use two pointers!
-<br><img src="https://assets.leetcode.com/uploads/2019/10/20/hint_remove_element.png" width="500"/>
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Yet another direction of thought is to consider the elements to be removed as non-existent. In a single pass, if we keep copying the visible elements in-place, that should also solve this problem for us.
-</details>
diff --git a/problems/remove-element/remove_element.go b/problems/remove-element/remove_element.go
deleted file mode 100644
index 582ac0057..000000000
--- a/problems/remove-element/remove_element.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem27
-
-func removeElement(nums []int, val int) int {
-	l := 0
-	for _, v := range nums {
-		if v != val {
-			nums[l] = v
-			l++
-		}
-	}
-	return l
-}
diff --git a/problems/remove-element/remove_element_test.go b/problems/remove-element/remove_element_test.go
deleted file mode 100644
index b7658f30f..000000000
--- a/problems/remove-element/remove_element_test.go
+++ /dev/null
@@ -1,52 +0,0 @@
-package problem27
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	val  int
-	want []int
-}
-
-func TestRemoveElement(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 2, 2, 3},
-			val:  3,
-			want: []int{2, 2},
-		},
-		{
-			in:   []int{0, 1, 2, 2, 3, 0, 4, 2},
-			val:  2,
-			want: []int{0, 1, 3, 0, 4},
-		},
-		{
-			in:   []int{1, 2, 3, 4, 5},
-			val:  6,
-			want: []int{1, 2, 3, 4, 5},
-		},
-		{
-			in:   []int{1, 2, 2, 3, 3, 3, 4, 4, 4, 4},
-			val:  4,
-			want: []int{1, 2, 2, 3, 3, 3},
-		},
-		{
-			in:   []int{},
-			val:  1,
-			want: []int{},
-		},
-	}
-
-	for _, tt := range tests {
-		nums := make([]int, len(tt.in))
-		copy(nums, tt.in)
-		l := removeElement(nums, tt.val)
-		got := nums[:l]
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/remove-interval/README.md b/problems/remove-interval/README.md
deleted file mode 100644
index bce96a0c0..000000000
--- a/problems/remove-interval/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../hexspeak "Hexspeak")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-tree-nodes "Delete Tree Nodes")
-
-## [1272. Remove Interval (Medium)](https://leetcode.com/problems/remove-interval "删除区间")
-
-<p>Given a <strong>sorted</strong> list of disjoint <code>intervals</code>, each interval <code>intervals[i] = [a, b]</code> represents the set of real numbers&nbsp;<code>x</code> such that&nbsp;<code>a &lt;= x &lt; b</code>.</p>
-
-<p>We remove the intersections between any interval in <code>intervals</code> and the interval <code>toBeRemoved</code>.</p>
-
-<p>Return a <strong>sorted</strong>&nbsp;list of <code>intervals</code> after all such removals.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> intervals = [[0,2],[3,4],[5,7]], toBeRemoved = [1,6]
-<strong>Output:</strong> [[0,1],[6,7]]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> intervals = [[0,5]], toBeRemoved = [2,3]
-<strong>Output:</strong> [[0,2],[3,5]]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= intervals.length &lt;= 10^4</code></li>
-	<li><code>-10^9 &lt;= intervals[i][0] &lt; intervals[i][1] &lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Solve the problem for every interval alone.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Divide the problem into cases according to the position of the two intervals.
-</details>
diff --git a/problems/remove-invalid-parentheses/README.md b/problems/remove-invalid-parentheses/README.md
deleted file mode 100644
index 81d23cba2..000000000
--- a/problems/remove-invalid-parentheses/README.md
+++ /dev/null
@@ -1,110 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-increasing-subsequence "Longest Increasing Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-rectangle-enclosing-black-pixels "Smallest Rectangle Enclosing Black Pixels")
-
-## [301. Remove Invalid Parentheses (Hard)](https://leetcode.com/problems/remove-invalid-parentheses "删除无效的括号")
-
-<p>Given a string <code>s</code> that contains parentheses and letters, remove the minimum number of invalid parentheses to make the input string valid.</p>
-
-<p>Return <em>all the possible results</em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;()())()&quot;
-<strong>Output:</strong> [&quot;(())()&quot;,&quot;()()()&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(a)())()&quot;
-<strong>Output:</strong> [&quot;(a())()&quot;,&quot;(a)()()&quot;]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;)(&quot;
-<strong>Output:</strong> [&quot;&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 25</code></li>
-	<li><code>s</code> consists of lowercase English letters and parentheses <code>&#39;(&#39;</code> and <code>&#39;)&#39;</code>.</li>
-	<li>There will be at most <code>20</code> parentheses in <code>s</code>.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Valid Parentheses](../valid-parentheses) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since we don't know which of the brackets can possibly be removed, we try out all the options!
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can use recursion to try out all possibilities for the given expression. For each of the brackets, we have 2 options:
-
-<ol>
-<li> We keep the bracket and add it to the expression that we are building on the fly during recursion.</li>
-<li> OR, we can discard the bracket and move on.
-</ol>
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The one thing all these valid expressions have in common is that they will all be of the same length i.e. as compared to the original expression, all of these expressions will have the same number of characters removed. 
-
-Can we somehow find the number of misplaced parentheses and use it in our solution?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The one thing all these valid expressions have in common is that they will all be of the same length i.e. as compared to the original expression, all of these expressions will have the same number of characters removed. 
-
-Can we somehow find the number of misplaced parentheses and use it in our solution?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-For every left parenthesis, we should have a corresponding right parenthesis. We can make use of two counters which keep track of misplaced left and right parenthesis and in one iteration we can find out these two values. 
-
-<pre>
-0 1 2 3 4 5 6 7
-( ) ) ) ( ( ( )  
-i = 0, left = 1, right = 0
-i = 1, left = 0, right = 0
-i = 2, left = 0, right = 1
-i = 3, left = 0, right = 2
-i = 4, left = 1, right = 2
-i = 5, left = 2, right = 2
-i = 6, left = 3, right = 2
-i = 7, left = 2, right = 2
-</pre>
-
-We have 2 misplaced left and 2 misplaced right parentheses.
-</details>
-
-<details>
-<summary>Hint 6</summary>
-We found out that the exact number of left and right parenthesis that has to be removed to get a valid expression. So, e.g. in a 1000 parentheses string, if there are 2 misplaced left and 2 misplaced right parentheses, after we are done discarding 2 left and 2 right parentheses, we will have only one option per remaining character in the expression i.e. to consider them. We can't discard them.
-</details>
diff --git a/problems/remove-invalid-parentheses/remove_invalid_parentheses.go b/problems/remove-invalid-parentheses/remove_invalid_parentheses.go
deleted file mode 100644
index 28d7ed9df..000000000
--- a/problems/remove-invalid-parentheses/remove_invalid_parentheses.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem301
diff --git a/problems/remove-invalid-parentheses/remove_invalid_parentheses_test.go b/problems/remove-invalid-parentheses/remove_invalid_parentheses_test.go
deleted file mode 100644
index 28d7ed9df..000000000
--- a/problems/remove-invalid-parentheses/remove_invalid_parentheses_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem301
diff --git a/problems/remove-k-digits/README.md b/problems/remove-k-digits/README.md
deleted file mode 100644
index 51f3dea55..000000000
--- a/problems/remove-k-digits/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-watch "Binary Watch")
-　　　　　　　　　　　　　　　　
-[Next >](../frog-jump "Frog Jump")
-
-## [402. Remove K Digits (Medium)](https://leetcode.com/problems/remove-k-digits "移掉 K 位数字")
-
-<p>Given string num representing a non-negative integer <code>num</code>, and an integer <code>k</code>, return <em>the smallest possible integer after removing</em> <code>k</code> <em>digits from</em> <code>num</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;1432219&quot;, k = 3
-<strong>Output:</strong> &quot;1219&quot;
-<strong>Explanation:</strong> Remove the three digits 4, 3, and 2 to form the new number 1219 which is the smallest.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;10200&quot;, k = 1
-<strong>Output:</strong> &quot;200&quot;
-<strong>Explanation:</strong> Remove the leading 1 and the number is 200. Note that the output must not contain leading zeroes.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;10&quot;, k = 2
-<strong>Output:</strong> &quot;0&quot;
-<strong>Explanation:</strong> Remove all the digits from the number and it is left with nothing which is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= num.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>num</code> consists of only digits.</li>
-	<li><code>num</code> does not have any leading zeros except for the zero itself.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Create Maximum Number](../create-maximum-number) (Hard)
-  1. [Monotone Increasing Digits](../monotone-increasing-digits) (Medium)
diff --git a/problems/remove-k-digits/remove_k_digits.go b/problems/remove-k-digits/remove_k_digits.go
deleted file mode 100644
index dbb2c155e..000000000
--- a/problems/remove-k-digits/remove_k_digits.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem402
diff --git a/problems/remove-k-digits/remove_k_digits_test.go b/problems/remove-k-digits/remove_k_digits_test.go
deleted file mode 100644
index dbb2c155e..000000000
--- a/problems/remove-k-digits/remove_k_digits_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem402
diff --git a/problems/remove-linked-list-elements/README.md b/problems/remove-linked-list-elements/README.md
deleted file mode 100644
index dc2467d0b..000000000
--- a/problems/remove-linked-list-elements/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../happy-number "Happy Number")
-　　　　　　　　　　　　　　　　
-[Next >](../count-primes "Count Primes")
-
-## [203. Remove Linked List Elements (Easy)](https://leetcode.com/problems/remove-linked-list-elements "移除链表元素")
-
-<p>Given the <code>head</code> of a linked list and an integer <code>val</code>, remove all the nodes of the linked list that has <code>Node.val == val</code>, and return <em>the new head</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/06/removelinked-list.jpg" style="width: 500px; height: 142px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,6,3,4,5,6], val = 6
-<strong>Output:</strong> [1,2,3,4,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [], val = 1
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [7,7,7,7], val = 7
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 50</code></li>
-	<li><code>0 &lt;= val &lt;= 50</code></li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Remove Element](../remove-element) (Easy)
-  1. [Delete Node in a Linked List](../delete-node-in-a-linked-list) (Easy)
diff --git a/problems/remove-linked-list-elements/remove_linked_list_elements.go b/problems/remove-linked-list-elements/remove_linked_list_elements.go
deleted file mode 100644
index 3a6c5403c..000000000
--- a/problems/remove-linked-list-elements/remove_linked_list_elements.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem203
diff --git a/problems/remove-linked-list-elements/remove_linked_list_elements_test.go b/problems/remove-linked-list-elements/remove_linked_list_elements_test.go
deleted file mode 100644
index 3a6c5403c..000000000
--- a/problems/remove-linked-list-elements/remove_linked_list_elements_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem203
diff --git a/problems/remove-max-number-of-edges-to-keep-graph-fully-traversable/README.md b/problems/remove-max-number-of-edges-to-keep-graph-fully-traversable/README.md
deleted file mode 100644
index 11e59e27d..000000000
--- a/problems/remove-max-number-of-edges-to-keep-graph-fully-traversable/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-time-to-make-rope-colorful "Minimum Time to Make Rope Colorful")
-　　　　　　　　　　　　　　　　
-[Next >](../put-boxes-into-the-warehouse-ii "Put Boxes Into the Warehouse II")
-
-## [1579. Remove Max Number of Edges to Keep Graph Fully Traversable (Hard)](https://leetcode.com/problems/remove-max-number-of-edges-to-keep-graph-fully-traversable "保证图可完全遍历")
-
-<p>Alice and Bob have an undirected graph of&nbsp;<code>n</code>&nbsp;nodes&nbsp;and 3 types of edges:</p>
-
-<ul>
-	<li>Type 1: Can be traversed by Alice only.</li>
-	<li>Type 2: Can be traversed by Bob only.</li>
-	<li>Type 3: Can by traversed by both Alice and Bob.</li>
-</ul>
-
-<p>Given an array&nbsp;<code>edges</code>&nbsp;where&nbsp;<code>edges[i] = [type<sub>i</sub>, u<sub>i</sub>, v<sub>i</sub>]</code>&nbsp;represents a bidirectional edge of type&nbsp;<code>type<sub>i</sub></code>&nbsp;between nodes&nbsp;<code>u<sub>i</sub></code>&nbsp;and&nbsp;<code>v<sub>i</sub></code>, find the maximum number of edges you can remove so that after removing the edges, the graph can still be fully traversed by both Alice and Bob. The graph is fully traversed by Alice and Bob if starting from any node, they can reach all other nodes.</p>
-
-<p>Return <em>the maximum number of edges you can remove, or return</em> <code>-1</code> <em>if it&#39;s impossible for the graph to be fully traversed by Alice and Bob.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/08/19/ex1.png" style="width: 179px; height: 191px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, edges = [[3,1,2],[3,2,3],[1,1,3],[1,2,4],[1,1,2],[2,3,4]]
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>If we remove the 2 edges [1,1,2] and [1,1,3]. The graph will still be fully traversable by Alice and Bob. Removing any additional edge will not make it so. So the maximum number of edges we can remove is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/08/19/ex2.png" style="width: 178px; height: 190px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, edges = [[3,1,2],[3,2,3],[1,1,4],[2,1,4]]
-<strong>Output:</strong> 0
-<strong>Explanation: </strong>Notice that removing any edge will not make the graph fully traversable by Alice and Bob.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/08/19/ex3.png" style="width: 178px; height: 190px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, edges = [[3,2,3],[1,1,2],[2,3,4]]
-<strong>Output:</strong> -1
-<b>Explanation: </b>In the current graph, Alice cannot reach node 4 from the other nodes. Likewise, Bob cannot reach 1. Therefore it&#39;s impossible to make the graph fully traversable.</pre>
-
-<p>&nbsp;</p>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10^5</code></li>
-	<li><code>1 &lt;= edges.length &lt;= min(10^5, 3 * n * (n-1) / 2)</code></li>
-	<li><code>edges[i].length == 3</code></li>
-	<li><code>1 &lt;= edges[i][0] &lt;= 3</code></li>
-	<li><code>1 &lt;= edges[i][1] &lt; edges[i][2] &lt;= n</code></li>
-	<li>All tuples&nbsp;<code>(type<sub>i</sub>, u<sub>i</sub>, v<sub>i</sub>)</code>&nbsp;are distinct.</li>
-</ul>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Build the network instead of removing extra edges.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Suppose you have the final graph (after removing extra edges). Consider the subgraph with only the edges that Alice can traverse. What structure does this subgraph have? How many edges are there?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use disjoint set union data structure for both Alice and Bob.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Always use Type 3 edges first, and connect the still isolated ones using other edges.
-</details>
diff --git a/problems/remove-nth-node-from-end-of-list/README.md b/problems/remove-nth-node-from-end-of-list/README.md
deleted file mode 100644
index 908f284b4..000000000
--- a/problems/remove-nth-node-from-end-of-list/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../4sum "4Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-parentheses "Valid Parentheses")
-
-## [19. Remove Nth Node From End of List (Medium)](https://leetcode.com/problems/remove-nth-node-from-end-of-list "删除链表的倒数第 N 个结点")
-
-<p>Given the <code>head</code> of a linked list, remove the <code>n<sup>th</sup></code> node from the end of the list and return its head.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/remove_ex1.jpg" style="width: 542px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5], n = 2
-<strong>Output:</strong> [1,2,3,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1], n = 1
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1,2], n = 1
-<strong>Output:</strong> [1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is <code>sz</code>.</li>
-	<li><code>1 &lt;= sz &lt;= 30</code></li>
-	<li><code>0 &lt;= Node.val &lt;= 100</code></li>
-	<li><code>1 &lt;= n &lt;= sz</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you do this in one pass?</p>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Maintain two pointers and update one with a delay of n steps.
-</details>
diff --git a/problems/remove-nth-node-from-end-of-list/remove_nth_node_from_end_of_list.go b/problems/remove-nth-node-from-end-of-list/remove_nth_node_from_end_of_list.go
deleted file mode 100644
index 713467b36..000000000
--- a/problems/remove-nth-node-from-end-of-list/remove_nth_node_from_end_of_list.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package problem19
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func removeNthFromEnd(head *ListNode, n int) *ListNode {
-	ans := &ListNode{Next: head}
-	pos := ans
-	for head != nil {
-		head = head.Next
-		if n > 0 {
-			n--
-		} else {
-			pos = pos.Next
-		}
-	}
-	pos.Next = pos.Next.Next
-	return ans.Next
-}
diff --git a/problems/remove-nth-node-from-end-of-list/remove_nth_node_from_end_of_list_test.go b/problems/remove-nth-node-from-end-of-list/remove_nth_node_from_end_of_list_test.go
deleted file mode 100644
index f8dc2cff8..000000000
--- a/problems/remove-nth-node-from-end-of-list/remove_nth_node_from_end_of_list_test.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package problem19
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	n    int
-	want []int
-}
-
-func TestRemoveNthFromEnd(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3, 4, 5},
-			n:    2,
-			want: []int{1, 2, 3, 5},
-		},
-		{
-			in:   []int{1, 2, 3, 4, 5},
-			n:    5,
-			want: []int{2, 3, 4, 5},
-		},
-		{
-			in:   []int{1, 2, 3, 4, 5},
-			n:    1,
-			want: []int{1, 2, 3, 4},
-		},
-	}
-	for _, tt := range tests {
-		got := removeNthFromEnd(kit.SliceInt2ListNode(tt.in), tt.n)
-		if !reflect.DeepEqual(kit.ListNode2SliceInt(got), tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/remove-one-element-to-make-the-array-strictly-increasing/README.md b/problems/remove-one-element-to-make-the-array-strictly-increasing/README.md
deleted file mode 100644
index 2a1183730..000000000
--- a/problems/remove-one-element-to-make-the-array-strictly-increasing/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../game-of-nim "Game of Nim")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-all-occurrences-of-a-substring "Remove All Occurrences of a Substring")
-
-## [1909. Remove One Element to Make the Array Strictly Increasing (Easy)](https://leetcode.com/problems/remove-one-element-to-make-the-array-strictly-increasing "删除一个元素使数组严格递增")
-
-<p>Given a <strong>0-indexed</strong> integer array <code>nums</code>, return <code>true</code> <em>if it can be made <strong>strictly increasing</strong> after removing <strong>exactly one</strong> element, or </em><code>false</code><em> otherwise. If the array is already strictly increasing, return </em><code>true</code>.</p>
-
-<p>The array <code>nums</code> is <strong>strictly increasing</strong> if <code>nums[i - 1] &lt; nums[i]</code> for each index <code>(1 &lt;= i &lt; nums.length).</code></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,<u>10</u>,5,7]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> By removing 10 at index 2 from nums, it becomes [1,2,5,7].
-[1,2,5,7] is strictly increasing, so return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,1,2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-[3,1,2] is the result of removing the element at index 0.
-[2,1,2] is the result of removing the element at index 1.
-[2,3,2] is the result of removing the element at index 2.
-[2,3,1] is the result of removing the element at index 3.
-No resulting array is strictly increasing, so return false.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The result of removing any element is [1,1].
-[1,1] is not strictly increasing, so return false.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each index i in nums remove this index.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the array becomes sorted return true, otherwise revert to the original array and try different index.
-</details>
diff --git a/problems/remove-outermost-parentheses/README.md b/problems/remove-outermost-parentheses/README.md
deleted file mode 100644
index 50cf3f963..000000000
--- a/problems/remove-outermost-parentheses/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-enclaves "Number of Enclaves")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-root-to-leaf-binary-numbers "Sum of Root To Leaf Binary Numbers")
-
-## [1021. Remove Outermost Parentheses (Easy)](https://leetcode.com/problems/remove-outermost-parentheses "删除最外层的括号")
-
-<p>A valid parentheses string is either empty <code>&quot;&quot;</code>, <code>&quot;(&quot; + A + &quot;)&quot;</code>, or <code>A + B</code>, where <code>A</code> and <code>B</code> are valid parentheses strings, and <code>+</code> represents string concatenation.</p>
-
-<ul>
-	<li>For example, <code>&quot;&quot;</code>, <code>&quot;()&quot;</code>, <code>&quot;(())()&quot;</code>, and <code>&quot;(()(()))&quot;</code> are all valid parentheses strings.</li>
-</ul>
-
-<p>A valid parentheses string <code>s</code> is primitive if it is nonempty, and there does not exist a way to split it into <code>s = A + B</code>, with <code>A</code> and <code>B</code> nonempty valid parentheses strings.</p>
-
-<p>Given a valid parentheses string <code>s</code>, consider its primitive decomposition: <code>s = P<sub>1</sub> + P<sub>2</sub> + ... + P<sub>k</sub></code>, where <code>P<sub>i</sub></code> are primitive valid parentheses strings.</p>
-
-<p>Return <code>s</code> <em>after removing the outermost parentheses of every primitive string in the primitive decomposition of </em><code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(()())(())&quot;
-<strong>Output:</strong> &quot;()()()&quot;
-<strong>Explanation:</strong> 
-The input string is &quot;(()())(())&quot;, with primitive decomposition &quot;(()())&quot; + &quot;(())&quot;.
-After removing outer parentheses of each part, this is &quot;()()&quot; + &quot;()&quot; = &quot;()()()&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(()())(())(()(()))&quot;
-<strong>Output:</strong> &quot;()()()()(())&quot;
-<strong>Explanation:</strong> 
-The input string is &quot;(()())(())(()(()))&quot;, with primitive decomposition &quot;(()())&quot; + &quot;(())&quot; + &quot;(()(()))&quot;.
-After removing outer parentheses of each part, this is &quot;()()&quot; + &quot;()&quot; + &quot;()(())&quot; = &quot;()()()()(())&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;()()&quot;
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> 
-The input string is &quot;()()&quot;, with primitive decomposition &quot;()&quot; + &quot;()&quot;.
-After removing outer parentheses of each part, this is &quot;&quot; + &quot;&quot; = &quot;&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;(&#39;</code> or <code>&#39;)&#39;</code>.</li>
-	<li><code>s</code> is a valid parentheses string.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you find the primitive decomposition?  The number of ( and ) characters must be equal.
-</details>
diff --git a/problems/remove-outermost-parentheses/remove_outermost_parentheses.go b/problems/remove-outermost-parentheses/remove_outermost_parentheses.go
deleted file mode 100644
index 0bcef81ef..000000000
--- a/problems/remove-outermost-parentheses/remove_outermost_parentheses.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem1021
-
-func removeOuterParentheses(S string) string {
-	ans, n := make([]rune, 0, len(S)), 0
-	for _, c := range S {
-		if c == '(' {
-			n++
-		} else {
-			n--
-		}
-		if (c == '(' && n != 1) || (c == ')' && n != 0) {
-			ans = append(ans, c)
-		}
-	}
-	return string(ans)
-}
diff --git a/problems/remove-outermost-parentheses/remove_outermost_parentheses_test.go b/problems/remove-outermost-parentheses/remove_outermost_parentheses_test.go
deleted file mode 100644
index a2c1f36ca..000000000
--- a/problems/remove-outermost-parentheses/remove_outermost_parentheses_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem1021
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestRemoveOuterParentheses(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "(()())(())",
-			want: "()()()",
-		},
-		{
-			in:   "(()())(())(()(()))",
-			want: "()()()()(())",
-		},
-		{
-			in:   "()()",
-			want: "",
-		},
-	}
-	for _, tt := range tests {
-		got := removeOuterParentheses(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/remove-palindromic-subsequences/README.md b/problems/remove-palindromic-subsequences/README.md
deleted file mode 100644
index 9127113a0..000000000
--- a/problems/remove-palindromic-subsequences/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rank-transform-of-an-array "Rank Transform of an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../filter-restaurants-by-vegan-friendly-price-and-distance "Filter Restaurants by Vegan-Friendly, Price and Distance")
-
-## [1332. Remove Palindromic Subsequences (Easy)](https://leetcode.com/problems/remove-palindromic-subsequences "删除回文子序列")
-
-<p>You are given a string <code>s</code> consisting <strong>only</strong> of letters <code>&#39;a&#39;</code> and <code>&#39;b&#39;</code>. In a single step you can remove one <strong>palindromic subsequence</strong> from <code>s</code>.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of steps to make the given string empty</em>.</p>
-
-<p>A string is a <strong>subsequence</strong> of a given string if it is generated by deleting some characters of a given string without changing its order. Note that a subsequence does <strong>not</strong> necessarily need to be contiguous.</p>
-
-<p>A string is called <strong>palindrome</strong> if is one that reads the same backward as well as forward.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ababa&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> s is already a palindrome, so its entirety can be removed in a single step.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abb&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> &quot;<u>a</u>bb&quot; -&gt; &quot;<u>bb</u>&quot; -&gt; &quot;&quot;. 
-Remove palindromic subsequence &quot;a&quot; then &quot;bb&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;baabb&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> &quot;<u>baa</u>b<u>b</u>&quot; -&gt; &quot;<u>b</u>&quot; -&gt; &quot;&quot;. 
-Remove palindromic subsequence &quot;baab&quot; then &quot;b&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s[i]</code> is either <code>&#39;a&#39;</code> or <code>&#39;b&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use the fact that string contains only 2 characters.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Are subsequences composed of only one type of letter always palindrome strings ?
-</details>
diff --git a/problems/remove-palindromic-subsequences/remove_palindromic_subsequences.go b/problems/remove-palindromic-subsequences/remove_palindromic_subsequences.go
deleted file mode 100644
index 4b96049a9..000000000
--- a/problems/remove-palindromic-subsequences/remove_palindromic_subsequences.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem1332
-
-func removePalindromeSub(s string) int {
-	if s == "" {
-		return 0
-	}
-	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
-		if s[i] != s[j] {
-			return 2
-		}
-	}
-	return 1
-}
diff --git a/problems/remove-palindromic-subsequences/remove_palindromic_subsequences_test.go b/problems/remove-palindromic-subsequences/remove_palindromic_subsequences_test.go
deleted file mode 100644
index d91a2bfff..000000000
--- a/problems/remove-palindromic-subsequences/remove_palindromic_subsequences_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem1332
-
-import "testing"
-
-type testType struct {
-	in   string
-	want int
-}
-
-func TestRemovePalindromeSub(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "ababa",
-			want: 1,
-		},
-		{
-			in:   "abb",
-			want: 2,
-		},
-		{
-			in:   "baabb",
-			want: 2,
-		},
-		{
-			in:   "",
-			want: 0,
-		},
-		{
-			in:   "aaabbbaaabbb",
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := removePalindromeSub(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/remove-stones-to-minimize-the-total/README.md b/problems/remove-stones-to-minimize-the-total/README.md
deleted file mode 100644
index 64414e15e..000000000
--- a/problems/remove-stones-to-minimize-the-total/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-string-is-a-prefix-of-array "Check If String Is a Prefix of Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-swaps-to-make-the-string-balanced "Minimum Number of Swaps to Make the String Balanced")
-
-## [1962. Remove Stones to Minimize the Total (Medium)](https://leetcode.com/problems/remove-stones-to-minimize-the-total "移除石子使总数最小")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>piles</code>, where <code>piles[i]</code> represents the number of stones in the <code>i<sup>th</sup></code> pile, and an integer <code>k</code>. You should apply the following operation <strong>exactly</strong> <code>k</code> times:</p>
-
-<ul>
-	<li>Choose any <code>piles[i]</code> and <strong>remove</strong> <code>floor(piles[i] / 2)</code> stones from it.</li>
-</ul>
-
-<p><strong>Notice</strong> that you can apply the operation on the <strong>same</strong> pile more than once.</p>
-
-<p>Return <em>the <strong>minimum</strong> possible total number of stones remaining after applying the </em><code>k</code><em> operations</em>.</p>
-
-<p><code>floor(x)</code> is the <b>greatest</b> integer that is <strong>smaller</strong> than or <strong>equal</strong> to <code>x</code> (i.e., rounds <code>x</code> down).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [5,4,9], k = 2
-<strong>Output:</strong> 12
-<strong>Explanation:</strong>&nbsp;Steps of a possible scenario are:
-- Apply the operation on pile 2. The resulting piles are [5,4,<u>5</u>].
-- Apply the operation on pile 0. The resulting piles are [<u>3</u>,4,5].
-The total number of stones in [3,4,5] is 12.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [4,3,6,7], k = 3
-<strong>Output:</strong> 12
-<strong>Explanation:</strong>&nbsp;Steps of a possible scenario are:
-- Apply the operation on pile 2. The resulting piles are [4,3,<u>3</u>,7].
-- Apply the operation on pile 3. The resulting piles are [4,3,3,<u>4</u>].
-- Apply the operation on pile 0. The resulting piles are [<u>2</u>,3,3,4].
-The total number of stones in [2,3,3,4] is 12.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= piles.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= piles[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Choose the pile with the maximum number of stones each time.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a data structure that helps you find the mentioned pile each time efficiently.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-One such data structure is a Priority Queue.
-</details>
diff --git a/problems/remove-sub-folders-from-the-filesystem/README.md b/problems/remove-sub-folders-from-the-filesystem/README.md
deleted file mode 100644
index 18bd119aa..000000000
--- a/problems/remove-sub-folders-from-the-filesystem/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-it-is-a-straight-line "Check If It Is a Straight Line")
-　　　　　　　　　　　　　　　　
-[Next >](../replace-the-substring-for-balanced-string "Replace the Substring for Balanced String")
-
-## [1233. Remove Sub-Folders from the Filesystem (Medium)](https://leetcode.com/problems/remove-sub-folders-from-the-filesystem "删除子文件夹")
-
-<p>Given a list of folders <code>folder</code>, return <em>the folders after removing all <strong>sub-folders</strong> in those folders</em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>If a <code>folder[i]</code> is located within another <code>folder[j]</code>, it is called a <strong>sub-folder</strong> of it.</p>
-
-<p>The format of a path is one or more concatenated strings of the form: <code>&#39;/&#39;</code> followed by one or more lowercase English letters.</p>
-
-<ul>
-	<li>For example, <code>&quot;/leetcode&quot;</code> and <code>&quot;/leetcode/problems&quot;</code> are valid paths while an empty string and <code>&quot;/&quot;</code> are not.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> folder = [&quot;/a&quot;,&quot;/a/b&quot;,&quot;/c/d&quot;,&quot;/c/d/e&quot;,&quot;/c/f&quot;]
-<strong>Output:</strong> [&quot;/a&quot;,&quot;/c/d&quot;,&quot;/c/f&quot;]
-<strong>Explanation:</strong> Folders &quot;/a/b/&quot; is a subfolder of &quot;/a&quot; and &quot;/c/d/e&quot; is inside of folder &quot;/c/d&quot; in our filesystem.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> folder = [&quot;/a&quot;,&quot;/a/b/c&quot;,&quot;/a/b/d&quot;]
-<strong>Output:</strong> [&quot;/a&quot;]
-<strong>Explanation:</strong> Folders &quot;/a/b/c&quot; and &quot;/a/b/d/&quot; will be removed because they are subfolders of &quot;/a&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> folder = [&quot;/a/b/c&quot;,&quot;/a/b/ca&quot;,&quot;/a/b/d&quot;]
-<strong>Output:</strong> [&quot;/a/b/c&quot;,&quot;/a/b/ca&quot;,&quot;/a/b/d&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= folder.length &lt;= 4 * 10<sup>4</sup></code></li>
-	<li><code>2 &lt;= folder[i].length &lt;= 100</code></li>
-	<li><code>folder[i]</code> contains only lowercase letters and <code>&#39;/&#39;</code>.</li>
-	<li><code>folder[i]</code> always starts with the character <code>&#39;/&#39;</code>.</li>
-	<li>Each folder name is <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the folders lexicographically.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Insert the current element in an array and then loop until we get rid of all of their subfolders, repeat this until no element is left.
-</details>
diff --git a/problems/remove-vowels-from-a-string/README.md b/problems/remove-vowels-from-a-string/README.md
deleted file mode 100644
index 35d9277c6..000000000
--- a/problems/remove-vowels-from-a-string/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-days-in-a-month "Number of Days in a Month")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-average-subtree "Maximum Average Subtree")
-
-## [1119. Remove Vowels from a String (Easy)](https://leetcode.com/problems/remove-vowels-from-a-string "删去字符串中的元音")
-
-<p>Given a string <code>S</code>, remove the vowels <code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, and <code>&#39;u&#39;</code> from it, and return the new string.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">&quot;leetcodeisacommunityforcoders&quot;</span>
-<strong>Output: </strong><span id="example-output-1">&quot;ltcdscmmntyfrcdrs&quot;</span>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">&quot;aeiou&quot;</span>
-<strong>Output: </strong><span id="example-output-2">&quot;&quot;</span>
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>S</code> consists of lowercase English letters only.</li>
-	<li><code>1 &lt;= S.length &lt;= 1000</code></li>
-</ol>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Reverse Vowels of a String](../reverse-vowels-of-a-string) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to erase vowels in a string?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop over the string and check every character, if it is a vowel ignore it otherwise add it to the answer.
-</details>
diff --git a/problems/remove-zero-sum-consecutive-nodes-from-linked-list/README.md b/problems/remove-zero-sum-consecutive-nodes-from-linked-list/README.md
deleted file mode 100644
index 674f758f7..000000000
--- a/problems/remove-zero-sum-consecutive-nodes-from-linked-list/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../compare-strings-by-frequency-of-the-smallest-character "Compare Strings by Frequency of the Smallest Character")
-　　　　　　　　　　　　　　　　
-[Next >](../dinner-plate-stacks "Dinner Plate Stacks")
-
-## [1171. Remove Zero Sum Consecutive Nodes from Linked List (Medium)](https://leetcode.com/problems/remove-zero-sum-consecutive-nodes-from-linked-list "从链表中删去总和值为零的连续节点")
-
-<p>Given the <code>head</code> of a linked list, we repeatedly delete consecutive sequences of nodes that sum to <code>0</code> until there are no such sequences.</p>
-
-<p>After doing so, return the head of the final linked list.&nbsp; You may return any such answer.</p>
-
-<p>&nbsp;</p>
-<p>(Note that in the examples below, all sequences are serializations of <code>ListNode</code> objects.)</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1,2,-3,3,1]
-<strong>Output:</strong> [3,1]
-<strong>Note:</strong> The answer [1,2,1] would also be accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1,2,3,-3,4]
-<strong>Output:</strong> [1,2,4]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1,2,3,-3,-2]
-<strong>Output:</strong> [1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The given linked list will contain between <code>1</code> and <code>1000</code> nodes.</li>
-	<li>Each node in the linked list has <code>-1000 &lt;= node.val &lt;= 1000</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Delete N Nodes After M Nodes of a Linked List](../delete-n-nodes-after-m-nodes-of-a-linked-list) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert the linked list into an array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-While you can find a non-empty subarray with sum = 0, erase it.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Convert the array into a linked list.
-</details>
diff --git a/problems/removing-minimum-and-maximum-from-array/README.md b/problems/removing-minimum-and-maximum-from-array/README.md
deleted file mode 100644
index 6a9d08876..000000000
--- a/problems/removing-minimum-and-maximum-from-array/README.md
+++ /dev/null
@@ -1,94 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-radius-subarray-averages "K Radius Subarray Averages")
-　　　　　　　　　　　　　　　　
-[Next >](../find-all-people-with-secret "Find All People With Secret")
-
-## [2091. Removing Minimum and Maximum From Array (Medium)](https://leetcode.com/problems/removing-minimum-and-maximum-from-array "从数组中移除最大值和最小值")
-
-<p>You are given a <strong>0-indexed</strong> array of <strong>distinct</strong> integers <code>nums</code>.</p>
-
-<p>There is an element in <code>nums</code> that has the <strong>lowest</strong> value and an element that has the <strong>highest</strong> value. We call them the <strong>minimum</strong> and <strong>maximum</strong> respectively. Your goal is to remove <strong>both</strong> these elements from the array.</p>
-
-<p>A <strong>deletion</strong> is defined as either removing an element from the <strong>front</strong> of the array or removing an element from the <strong>back</strong> of the array.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of deletions it would take to remove <strong>both</strong> the minimum and maximum element from the array.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,<u><strong>10</strong></u>,7,5,4,<u><strong>1</strong></u>,8,6]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> 
-The minimum element in the array is nums[5], which is 1.
-The maximum element in the array is nums[1], which is 10.
-We can remove both the minimum and maximum by removing 2 elements from the front and 3 elements from the back.
-This results in 2 + 3 = 5 deletions, which is the minimum number possible.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,<u><strong>-4</strong></u>,<u><strong>19</strong></u>,1,8,-2,-3,5]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-The minimum element in the array is nums[1], which is -4.
-The maximum element in the array is nums[2], which is 19.
-We can remove both the minimum and maximum by removing 3 elements from the front.
-This results in only 3 deletions, which is the minimum number possible.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [<u><strong>101</strong></u>]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>  
-There is only one element in the array, which makes it both the minimum and maximum element.
-We can remove it with 1 deletion.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-	<li>The integers in <code>nums</code> are <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There can only be three scenarios for deletions such that both minimum and maximum elements are removed:
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Scenario 1: Both elements are removed by only deleting from the front.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Scenario 2: Both elements are removed by only deleting from the back.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Scenario 3: Delete from the front to remove one of the elements, and delete from the back to remove the other element.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Compare which of the three scenarios results in the minimum number of moves.
-</details>
diff --git a/problems/removing-minimum-number-of-magic-beans/README.md b/problems/removing-minimum-number-of-magic-beans/README.md
deleted file mode 100644
index 0e495bb15..000000000
--- a/problems/removing-minimum-number-of-magic-beans/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-operations-to-make-the-array-alternating "Minimum Operations to Make the Array Alternating")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-and-sum-of-array "Maximum AND Sum of Array")
-
-## [2171. Removing Minimum Number of Magic Beans (Medium)](https://leetcode.com/problems/removing-minimum-number-of-magic-beans "拿出最少数目的魔法豆")
-
-<p>You are given an array of <strong>positive</strong> integers <code>beans</code>, where each integer represents the number of magic beans found in a particular magic bag.</p>
-
-<p><strong>Remove</strong> any number of beans (<strong>possibly none</strong>) from each bag such that the number of beans in each remaining <strong>non-empty</strong> bag (still containing <strong>at least one</strong> bean) is <strong>equal</strong>. Once a bean has been removed from a bag, you are <strong>not</strong> allowed to return it to any of the bags.</p>
-
-<p>Return <em>the <strong>minimum</strong> number of magic beans that you have to remove</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> beans = [4,<u><strong>1</strong></u>,6,5]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> 
-- We remove 1 bean from the bag with only 1 bean.
-  This results in the remaining bags: [4,<b><u>0</u></b>,6,5]
-- Then we remove 2 beans from the bag with 6 beans.
-  This results in the remaining bags: [4,0,<strong><u>4</u></strong>,5]
-- Then we remove 1 bean from the bag with 5 beans.
-  This results in the remaining bags: [4,0,4,<b><u>4</u></b>]
-We removed a total of 1 + 2 + 1 = 4 beans to make the remaining non-empty bags have an equal number of beans.
-There are no other solutions that remove 4 beans or fewer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> beans = [<strong><u>2</u></strong>,10,<u><strong>3</strong></u>,<strong><u>2</u></strong>]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong>
-- We remove 2 beans from one of the bags with 2 beans.
-  This results in the remaining bags: [<u><strong>0</strong></u>,10,3,2]
-- Then we remove 2 beans from the other bag with 2 beans.
-  This results in the remaining bags: [0,10,3,<u><strong>0</strong></u>]
-- Then we remove 3 beans from the bag with 3 beans. 
-  This results in the remaining bags: [0,10,<u><strong>0</strong></u>,0]
-We removed a total of 2 + 2 + 3 = 7 beans to make the remaining non-empty bags have an equal number of beans.
-There are no other solutions that removes 7 beans or fewer.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= beans.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= beans[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Notice that if we choose to make x bags of beans empty, we should choose the x bags with the least amount of beans.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Notice that if the minimum number of beans in a non-empty bag is m, then the best way to make all bags have an equal amount of beans is to reduce all the bags to have m beans.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Can we iterate over how many bags we should remove and choose the one that minimizes the total amount of beans to remove?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Sort the bags of beans first.
-</details>
diff --git a/problems/reorder-data-in-log-files/README.md b/problems/reorder-data-in-log-files/README.md
deleted file mode 100644
index be87a55e4..000000000
--- a/problems/reorder-data-in-log-files/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stamping-the-sequence "Stamping The Sequence")
-　　　　　　　　　　　　　　　　
-[Next >](../range-sum-of-bst "Range Sum of BST")
-
-## [937. Reorder Data in Log Files (Easy)](https://leetcode.com/problems/reorder-data-in-log-files "重新排列日志文件")
-
-<p>You are given an array of <code>logs</code>. Each log is a space-delimited string of words, where the first word is the <strong>identifier</strong>.</p>
-
-<p>There are two types of logs:</p>
-
-<ul>
-	<li><b>Letter-logs</b>: All words (except the identifier) consist of lowercase English letters.</li>
-	<li><strong>Digit-logs</strong>: All words (except the identifier) consist of digits.</li>
-</ul>
-
-<p>Reorder these logs so that:</p>
-
-<ol>
-	<li>The <strong>letter-logs</strong> come before all <strong>digit-logs</strong>.</li>
-	<li>The <strong>letter-logs</strong> are sorted lexicographically by their contents. If their contents are the same, then sort them lexicographically by their identifiers.</li>
-	<li>The <strong>digit-logs</strong> maintain their relative ordering.</li>
-</ol>
-
-<p>Return <em>the final order of the logs</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> logs = [&quot;dig1 8 1 5 1&quot;,&quot;let1 art can&quot;,&quot;dig2 3 6&quot;,&quot;let2 own kit dig&quot;,&quot;let3 art zero&quot;]
-<strong>Output:</strong> [&quot;let1 art can&quot;,&quot;let3 art zero&quot;,&quot;let2 own kit dig&quot;,&quot;dig1 8 1 5 1&quot;,&quot;dig2 3 6&quot;]
-<strong>Explanation:</strong>
-The letter-log contents are all different, so their ordering is &quot;art can&quot;, &quot;art zero&quot;, &quot;own kit dig&quot;.
-The digit-logs have a relative order of &quot;dig1 8 1 5 1&quot;, &quot;dig2 3 6&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> logs = [&quot;a1 9 2 3 1&quot;,&quot;g1 act car&quot;,&quot;zo4 4 7&quot;,&quot;ab1 off key dog&quot;,&quot;a8 act zoo&quot;]
-<strong>Output:</strong> [&quot;g1 act car&quot;,&quot;a8 act zoo&quot;,&quot;ab1 off key dog&quot;,&quot;a1 9 2 3 1&quot;,&quot;zo4 4 7&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= logs.length &lt;= 100</code></li>
-	<li><code>3 &lt;= logs[i].length &lt;= 100</code></li>
-	<li>All the tokens of <code>logs[i]</code> are separated by a <strong>single</strong> space.</li>
-	<li><code>logs[i]</code> is guaranteed to have an identifier and at least one word after the identifier.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/reorder-data-in-log-files/reorder_data_in_log_files.go b/problems/reorder-data-in-log-files/reorder_data_in_log_files.go
deleted file mode 100644
index 96206a662..000000000
--- a/problems/reorder-data-in-log-files/reorder_data_in_log_files.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem937
-
-import (
-	"sort"
-	"strings"
-	"unicode"
-)
-
-func reorderLogFiles(logs []string) []string {
-	sort.SliceStable(logs, func(i, j int) bool {
-		s1 := strings.SplitN(logs[i], " ", 2)
-		s2 := strings.SplitN(logs[j], " ", 2)
-		f1, f2 := "0"+s1[1], "0"+s2[1]
-		if unicode.IsDigit(rune(f1[1])) {
-			f1 = "1"
-		}
-		if unicode.IsDigit(rune(f2[1])) {
-			f2 = "1"
-		}
-		return f1 < f2
-	})
-	return logs
-}
diff --git a/problems/reorder-data-in-log-files/reorder_data_in_log_files_test.go b/problems/reorder-data-in-log-files/reorder_data_in_log_files_test.go
deleted file mode 100644
index 8686e4724..000000000
--- a/problems/reorder-data-in-log-files/reorder_data_in_log_files_test.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package problem937
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []string
-	want []string
-}
-
-func TestReorderLogFiles(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []string{"a1 9 2 3 1", "g1 act car", "zo4 4 7", "ab1 off key dog", "a8 act zoo"},
-			want: []string{"g1 act car", "a8 act zoo", "ab1 off key dog", "a1 9 2 3 1", "zo4 4 7"},
-		},
-		{
-			in:   []string{"8 fj dzz k", "5r 446 6 3", "63 gu psub", "5 ba iedrz", "6s 87979 5", "3r 587 01", "jc 3480612", "bb wsrd kp", "b aq cojj", "r5 6316 71"},
-			want: []string{"b aq cojj", "5 ba iedrz", "8 fj dzz k", "63 gu psub", "bb wsrd kp", "5r 446 6 3", "6s 87979 5", "3r 587 01", "jc 3480612", "r5 6316 71"},
-		},
-		{
-			in:   []string{"qi ir oo i", "cp vnzw i", "0 fkbikbts", "4 j trouka", "gn j q al", "5r w wgqc", "m8 x haje", "fg 28694 6", "i gf mwdoa", "ao 0850716"},
-			want: []string{"0 fkbikbts", "i gf mwdoa", "qi ir oo i", "gn j q al", "4 j trouka", "cp vnzw i", "5r w wgqc", "m8 x haje", "fg 28694 6", "ao 0850716"},
-		},
-	}
-	for _, tt := range tests {
-		got := make([]string, len(tt.in))
-		copy(got, tt.in)
-		got = reorderLogFiles(got)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/reorder-list/README.md b/problems/reorder-list/README.md
deleted file mode 100644
index 7cd75f27e..000000000
--- a/problems/reorder-list/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../linked-list-cycle-ii "Linked List Cycle II")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-preorder-traversal "Binary Tree Preorder Traversal")
-
-## [143. Reorder List (Medium)](https://leetcode.com/problems/reorder-list "重排链表")
-
-<p>You are given the head of a singly linked-list. The list can be represented as:</p>
-
-<pre>
-L<sub>0</sub> &rarr; L<sub>1</sub> &rarr; &hellip; &rarr; L<sub>n - 1</sub> &rarr; L<sub>n</sub>
-</pre>
-
-<p><em>Reorder the list to be on the following form:</em></p>
-
-<pre>
-L<sub>0</sub> &rarr; L<sub>n</sub> &rarr; L<sub>1</sub> &rarr; L<sub>n - 1</sub> &rarr; L<sub>2</sub> &rarr; L<sub>n - 2</sub> &rarr; &hellip;
-</pre>
-
-<p>You may not modify the values in the list&#39;s nodes. Only nodes themselves may be changed.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/04/reorder1linked-list.jpg" style="width: 422px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4]
-<strong>Output:</strong> [1,4,2,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/09/reorder2-linked-list.jpg" style="width: 542px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5]
-<strong>Output:</strong> [1,5,2,4,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[1, 5 * 10<sup>4</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
diff --git a/problems/reorder-list/reorder_list.go b/problems/reorder-list/reorder_list.go
deleted file mode 100644
index d77f3c172..000000000
--- a/problems/reorder-list/reorder_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem143
diff --git a/problems/reorder-list/reorder_list_test.go b/problems/reorder-list/reorder_list_test.go
deleted file mode 100644
index d77f3c172..000000000
--- a/problems/reorder-list/reorder_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem143
diff --git a/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero/README.md b/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero/README.md
deleted file mode 100644
index 6743b154d..000000000
--- a/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts "Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts")
-　　　　　　　　　　　　　　　　
-[Next >](../probability-of-a-two-boxes-having-the-same-number-of-distinct-balls "Probability of a Two Boxes Having The Same Number of Distinct Balls")
-
-## [1466. Reorder Routes to Make All Paths Lead to the City Zero (Medium)](https://leetcode.com/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero "重新规划路线")
-
-<p>There are <code>n</code> cities numbered from <code>0</code> to <code>n - 1</code> and <code>n - 1</code> roads such that there is only one way to travel between two different cities (this network form a tree). Last year, The ministry of transport decided to orient the roads in one direction because they are too narrow.</p>
-
-<p>Roads are represented by <code>connections</code> where <code>connections[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> represents a road from city <code>a<sub>i</sub></code> to city <code>b<sub>i</sub></code>.</p>
-
-<p>This year, there will be a big event in the capital (city <code>0</code>), and many people want to travel to this city.</p>
-
-<p>Your task consists of reorienting some roads such that each city can visit the city <code>0</code>. Return the <strong>minimum</strong> number of edges changed.</p>
-
-<p>It&#39;s <strong>guaranteed</strong> that each city can reach city <code>0</code> after reorder.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/05/13/sample_1_1819.png" style="width: 311px; height: 189px;" />
-<pre>
-<strong>Input:</strong> n = 6, connections = [[0,1],[1,3],[2,3],[4,0],[4,5]]
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>Change the direction of edges show in red such that each node can reach the node 0 (capital).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/05/13/sample_2_1819.png" style="width: 509px; height: 79px;" />
-<pre>
-<strong>Input:</strong> n = 5, connections = [[1,0],[1,2],[3,2],[3,4]]
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>Change the direction of edges show in red such that each node can reach the node 0 (capital).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, connections = [[1,0],[2,0]]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>connections.length == n - 1</code></li>
-	<li><code>connections[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt;= n - 1</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Treat the graph as undirected. Start a dfs from the root, if you come across an edge in the forward direction, you need to reverse the edge.
-</details>
diff --git a/problems/reordered-power-of-2/README.md b/problems/reordered-power-of-2/README.md
deleted file mode 100644
index de7e05839..000000000
--- a/problems/reordered-power-of-2/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-gap "Binary Gap")
-　　　　　　　　　　　　　　　　
-[Next >](../advantage-shuffle "Advantage Shuffle")
-
-## [869. Reordered Power of 2 (Medium)](https://leetcode.com/problems/reordered-power-of-2 "重新排序得到 2 的幂")
-
-<p>You are given an integer <code>n</code>. We reorder the digits in any order (including the original order) such that the leading digit is not zero.</p>
-
-<p>Return <code>true</code> <em>if and only if we can do this so that the resulting number is a power of two</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 16
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 24
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 46
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/reordered-power-of-2/reordered_power_of_2.go b/problems/reordered-power-of-2/reordered_power_of_2.go
deleted file mode 100644
index ebe040ce6..000000000
--- a/problems/reordered-power-of-2/reordered_power_of_2.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem869
diff --git a/problems/reordered-power-of-2/reordered_power_of_2_test.go b/problems/reordered-power-of-2/reordered_power_of_2_test.go
deleted file mode 100644
index ebe040ce6..000000000
--- a/problems/reordered-power-of-2/reordered_power_of_2_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem869
diff --git a/problems/reorganize-string/README.md b/problems/reorganize-string/README.md
deleted file mode 100644
index dbc402d4e..000000000
--- a/problems/reorganize-string/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../toeplitz-matrix "Toeplitz Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../max-chunks-to-make-sorted-ii "Max Chunks To Make Sorted II")
-
-## [767. Reorganize String (Medium)](https://leetcode.com/problems/reorganize-string "重构字符串")
-
-<p>Given a string <code>s</code>, rearrange the characters of <code>s</code> so that any two adjacent characters are not the same.</p>
-
-<p>Return <em>any possible rearrangement of</em> <code>s</code> <em>or return</em> <code>&quot;&quot;</code> <em>if not possible</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "aab"
-<strong>Output:</strong> "aba"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "aaab"
-<strong>Output:</strong> ""
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 500</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Rearrange String k Distance Apart](../rearrange-string-k-distance-apart) (Hard)
-  1. [Task Scheduler](../task-scheduler) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Alternate placing the most common letters.
-</details>
diff --git a/problems/reorganize-string/reorganize_string.go b/problems/reorganize-string/reorganize_string.go
deleted file mode 100644
index fb241f075..000000000
--- a/problems/reorganize-string/reorganize_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem767
diff --git a/problems/reorganize-string/reorganize_string_test.go b/problems/reorganize-string/reorganize_string_test.go
deleted file mode 100644
index fb241f075..000000000
--- a/problems/reorganize-string/reorganize_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem767
diff --git a/problems/repeated-dna-sequences/README.md b/problems/repeated-dna-sequences/README.md
deleted file mode 100644
index 634d93c7f..000000000
--- a/problems/repeated-dna-sequences/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-words-in-a-string-ii "Reverse Words in a String II")
-　　　　　　　　　　　　　　　　
-[Next >](../best-time-to-buy-and-sell-stock-iv "Best Time to Buy and Sell Stock IV")
-
-## [187. Repeated DNA Sequences (Medium)](https://leetcode.com/problems/repeated-dna-sequences "重复的DNA序列")
-
-<p>The <strong>DNA sequence</strong> is composed of a series of nucleotides abbreviated as <code>&#39;A&#39;</code>, <code>&#39;C&#39;</code>, <code>&#39;G&#39;</code>, and <code>&#39;T&#39;</code>.</p>
-
-<ul>
-	<li>For example, <code>&quot;ACGAATTCCG&quot;</code> is a <strong>DNA sequence</strong>.</li>
-</ul>
-
-<p>When studying <strong>DNA</strong>, it is useful to identify repeated sequences within the DNA.</p>
-
-<p>Given a string <code>s</code> that represents a <strong>DNA sequence</strong>, return all the <strong><code>10</code>-letter-long</strong> sequences (substrings) that occur more than once in a DNA molecule. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT"
-<strong>Output:</strong> ["AAAAACCCCC","CCCCCAAAAA"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "AAAAAAAAAAAAA"
-<strong>Output:</strong> ["AAAAAAAAAA"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is either <code>&#39;A&#39;</code>, <code>&#39;C&#39;</code>, <code>&#39;G&#39;</code>, or <code>&#39;T&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
diff --git a/problems/repeated-dna-sequences/repeated_dna_sequences.go b/problems/repeated-dna-sequences/repeated_dna_sequences.go
deleted file mode 100644
index 7e62d9060..000000000
--- a/problems/repeated-dna-sequences/repeated_dna_sequences.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem187
diff --git a/problems/repeated-dna-sequences/repeated_dna_sequences_test.go b/problems/repeated-dna-sequences/repeated_dna_sequences_test.go
deleted file mode 100644
index 7e62d9060..000000000
--- a/problems/repeated-dna-sequences/repeated_dna_sequences_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem187
diff --git a/problems/repeated-string-match/README.md b/problems/repeated-string-match/README.md
deleted file mode 100644
index 49ac83fce..000000000
--- a/problems/repeated-string-match/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../redundant-connection-ii "Redundant Connection II")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-univalue-path "Longest Univalue Path")
-
-## [686. Repeated String Match (Medium)](https://leetcode.com/problems/repeated-string-match "重复叠加字符串匹配")
-
-<p>Given two strings <code>a</code> and <code>b</code>, return <em>the minimum number of times you should repeat string </em><code>a</code><em> so that string</em> <code>b</code> <em>is a substring of it</em>. If it is impossible for <code>b</code>​​​​​​ to be a substring of <code>a</code> after repeating it, return <code>-1</code>.</p>
-
-<p><strong>Notice:</strong> string <code>&quot;abc&quot;</code> repeated 0 times is <code>&quot;&quot;</code>, repeated 1 time is <code>&quot;abc&quot;</code> and repeated 2 times is <code>&quot;abcabc&quot;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;abcd&quot;, b = &quot;cdabcdab&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We return 3 because by repeating a three times &quot;ab<strong>cdabcdab</strong>cd&quot;, b is a substring of it.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;a&quot;, b = &quot;aa&quot;
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= a.length, b.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>a</code> and <code>b</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Similar Questions
-  1. [Repeated Substring Pattern](../repeated-substring-pattern) (Easy)
diff --git a/problems/repeated-string-match/repeated_string_match.go b/problems/repeated-string-match/repeated_string_match.go
deleted file mode 100644
index 4b50a105c..000000000
--- a/problems/repeated-string-match/repeated_string_match.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem686
-
-import "strings"
-
-func repeatedStringMatch(A string, B string) int {
-	count := len(B) / len(A)
-	if len(B)%len(A) > 0 {
-		count++
-	}
-	for times := 0; times < 2; times++ {
-		a := strings.Repeat(A, count)
-		if strings.Index(a, B) != -1 {
-			return count
-		}
-		count++
-	}
-	return -1
-}
diff --git a/problems/repeated-string-match/repeated_string_match_test.go b/problems/repeated-string-match/repeated_string_match_test.go
deleted file mode 100644
index 71f8f6f61..000000000
--- a/problems/repeated-string-match/repeated_string_match_test.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package problem686
-
-import "testing"
-
-type testType struct {
-	a    string
-	b    string
-	want int
-}
-
-func TestRepeatedStringMatch(t *testing.T) {
-	tests := [...]testType{
-		{
-			a:    "abcd",
-			b:    "cdabcdab",
-			want: 3,
-		},
-		{
-			a:    "abcdefg",
-			b:    "cde",
-			want: 1,
-		},
-		{
-			a:    "abc",
-			b:    "abcabc",
-			want: 2,
-		},
-		{
-			a:    "abc",
-			b:    "abcd",
-			want: -1,
-		},
-	}
-	for _, tt := range tests {
-		got := repeatedStringMatch(tt.a, tt.b)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.a, tt.b, got, tt.want)
-		}
-	}
-}
diff --git a/problems/repeated-substring-pattern/README.md b/problems/repeated-substring-pattern/README.md
deleted file mode 100644
index bbed9fa11..000000000
--- a/problems/repeated-substring-pattern/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../poor-pigs "Poor Pigs")
-　　　　　　　　　　　　　　　　
-[Next >](../lfu-cache "LFU Cache")
-
-## [459. Repeated Substring Pattern (Easy)](https://leetcode.com/problems/repeated-substring-pattern "重复的子字符串")
-
-<p>Given a string <code>s</code>, check if it can be constructed by taking a substring of it and appending multiple copies of the substring together.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abab&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> It is the substring &quot;ab&quot; twice.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aba&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcabcabcabc&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> It is the substring &quot;abc&quot; four times or the substring &quot;abcabc&quot; twice.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Similar Questions
-  1. [Implement strStr()](../implement-strstr) (Easy)
-  1. [Repeated String Match](../repeated-string-match) (Medium)
diff --git a/problems/repeated-substring-pattern/repeated_substring_pattern.go b/problems/repeated-substring-pattern/repeated_substring_pattern.go
deleted file mode 100644
index fed94c34e..000000000
--- a/problems/repeated-substring-pattern/repeated_substring_pattern.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem459
-
-import "strings"
-
-func repeatedSubstringPattern(s string) bool {
-	return strings.Contains((s + s)[1:2*len(s)-1], s)
-}
diff --git a/problems/repeated-substring-pattern/repeated_substring_pattern_test.go b/problems/repeated-substring-pattern/repeated_substring_pattern_test.go
deleted file mode 100644
index 9922234ac..000000000
--- a/problems/repeated-substring-pattern/repeated_substring_pattern_test.go
+++ /dev/null
@@ -1,54 +0,0 @@
-package problem459
-
-import "testing"
-
-type testType struct {
-	in   string
-	want bool
-}
-
-func TestRepeatedSubstringPattern(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "a",
-			want: false,
-		},
-		{
-			in:   "abab",
-			want: true,
-		},
-		{
-			in:   "aba",
-			want: false,
-		},
-		{
-			in:   "abaaba",
-			want: true,
-		},
-		{
-			in:   "abcabcabcabc",
-			want: true,
-		},
-		{
-			in:   "abbaabbaabba",
-			want: true,
-		},
-		{
-			in:   "abcabcabcdabcabcabcdabcabcabcd",
-			want: true,
-		},
-		{
-			in:   "abaabaabac",
-			want: false,
-		}, {
-			in:   "babbabbabbabbab",
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := repeatedSubstringPattern(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/replace-all-digits-with-characters/README.md b/problems/replace-all-digits-with-characters/README.md
deleted file mode 100644
index 03ef8a3ed..000000000
--- a/problems/replace-all-digits-with-characters/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../suspicious-bank-accounts "Suspicious Bank Accounts")
-　　　　　　　　　　　　　　　　
-[Next >](../seat-reservation-manager "Seat Reservation Manager")
-
-## [1844. Replace All Digits with Characters (Easy)](https://leetcode.com/problems/replace-all-digits-with-characters "将所有数字用字符替换")
-
-<p>You are given a <strong>0-indexed</strong> string <code>s</code> that has lowercase English letters in its <strong>even</strong> indices and digits in its <strong>odd</strong> indices.</p>
-
-<p>There is a function <code>shift(c, x)</code>, where <code>c</code> is a character and <code>x</code> is a digit, that returns the <code>x<sup>th</sup></code> character after <code>c</code>.</p>
-
-<ul>
-	<li>For example, <code>shift(&#39;a&#39;, 5) = &#39;f&#39;</code> and <code>shift(&#39;x&#39;, 0) = &#39;x&#39;</code>.</li>
-</ul>
-
-<p>For every <strong>odd</strong>&nbsp;index <code>i</code>, you want to replace the digit <code>s[i]</code> with <code>shift(s[i-1], s[i])</code>.</p>
-
-<p>Return <code>s</code><em> after replacing all digits. It is <strong>guaranteed</strong> that </em><code>shift(s[i-1], s[i])</code><em> will never exceed </em><code>&#39;z&#39;</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a1c1e1&quot;
-<strong>Output:</strong> &quot;abcdef&quot;
-<strong>Explanation: </strong>The digits are replaced as follows:
-- s[1] -&gt; shift(&#39;a&#39;,1) = &#39;b&#39;
-- s[3] -&gt; shift(&#39;c&#39;,1) = &#39;d&#39;
-- s[5] -&gt; shift(&#39;e&#39;,1) = &#39;f&#39;</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a1b2c3d4e&quot;
-<strong>Output:</strong> &quot;abbdcfdhe&quot;
-<strong>Explanation: </strong>The digits are replaced as follows:
-- s[1] -&gt; shift(&#39;a&#39;,1) = &#39;b&#39;
-- s[3] -&gt; shift(&#39;b&#39;,2) = &#39;d&#39;
-- s[5] -&gt; shift(&#39;c&#39;,3) = &#39;f&#39;
-- s[7] -&gt; shift(&#39;d&#39;,4) = &#39;h&#39;</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> consists only of lowercase English letters and digits.</li>
-	<li><code>shift(s[i-1], s[i]) &lt;= &#39;z&#39;</code> for all <strong>odd</strong> indices <code>i</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We just need to replace every even positioned character with the character s[i] positions ahead of the character preceding it
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Get the position of the preceeding character in alphabet then advance it s[i] positions and get the character at that position
-</details>
diff --git a/problems/replace-all-s-to-avoid-consecutive-repeating-characters/README.md b/problems/replace-all-s-to-avoid-consecutive-repeating-characters/README.md
deleted file mode 100644
index e9aadef5e..000000000
--- a/problems/replace-all-s-to-avoid-consecutive-repeating-characters/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-all-possible-routes "Count All Possible Routes")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers "Number of Ways Where Square of Number Is Equal to Product of Two Numbers")
-
-## [1576. Replace All ?'s to Avoid Consecutive Repeating Characters (Easy)](https://leetcode.com/problems/replace-all-s-to-avoid-consecutive-repeating-characters "替换所有的问号")
-
-<p>Given a string <code>s</code> containing only lowercase English letters and the <code>&#39;?&#39;</code> character, convert <strong>all </strong>the <code>&#39;?&#39;</code> characters into lowercase letters such that the final string does not contain any <strong>consecutive repeating </strong>characters. You <strong>cannot </strong>modify the non <code>&#39;?&#39;</code> characters.</p>
-
-<p>It is <strong>guaranteed </strong>that there are no consecutive repeating characters in the given string <strong>except </strong>for <code>&#39;?&#39;</code>.</p>
-
-<p>Return <em>the final string after all the conversions (possibly zero) have been made</em>. If there is more than one solution, return <strong>any of them</strong>. It can be shown that an answer is always possible with the given constraints.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;?zs&quot;
-<strong>Output:</strong> &quot;azs&quot;
-<strong>Explanation:</strong> There are 25 solutions for this problem. From &quot;azs&quot; to &quot;yzs&quot;, all are valid. Only &quot;z&quot; is an invalid modification as the string will consist of consecutive repeating characters in &quot;zzs&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ubv?w&quot;
-<strong>Output:</strong> &quot;ubvaw&quot;
-<strong>Explanation:</strong> There are 24 solutions for this problem. Only &quot;v&quot; and &quot;w&quot; are invalid modifications as the strings will consist of consecutive repeating characters in &quot;ubvvw&quot; and &quot;ubvww&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> consist of lowercase English letters and <code>&#39;?&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Processing string from left to right, whenever you get a ‘?’, check left character and right character, and select a character not equal to either of them
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Do take care to compare with replaced occurrence of ‘?’ when checking the left character.
-</details>
diff --git a/problems/replace-elements-with-greatest-element-on-right-side/README.md b/problems/replace-elements-with-greatest-element-on-right-side/README.md
deleted file mode 100644
index 211f24d21..000000000
--- a/problems/replace-elements-with-greatest-element-on-right-side/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-candies-you-can-get-from-boxes "Maximum Candies You Can Get from Boxes")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-mutated-array-closest-to-target "Sum of Mutated Array Closest to Target")
-
-## [1299. Replace Elements with Greatest Element on Right Side (Easy)](https://leetcode.com/problems/replace-elements-with-greatest-element-on-right-side "将每个元素替换为右侧最大元素")
-
-<p>Given an array <code>arr</code>,&nbsp;replace every element in that array with the greatest element among the elements to its&nbsp;right, and replace the last element with <code>-1</code>.</p>
-
-<p>After doing so, return the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [17,18,5,4,6,1]
-<strong>Output:</strong> [18,6,6,6,1,-1]
-<strong>Explanation:</strong> 
-- index 0 --&gt; the greatest element to the right of index 0 is index 1 (18).
-- index 1 --&gt; the greatest element to the right of index 1 is index 4 (6).
-- index 2 --&gt; the greatest element to the right of index 2 is index 4 (6).
-- index 3 --&gt; the greatest element to the right of index 3 is index 4 (6).
-- index 4 --&gt; the greatest element to the right of index 4 is index 5 (1).
-- index 5 --&gt; there are no elements to the right of index 5, so we put -1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [400]
-<strong>Output:</strong> [-1]
-<strong>Explanation:</strong> There are no elements to the right of index 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Two Furthest Houses With Different Colors](../two-furthest-houses-with-different-colors) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Loop through the array starting from the end.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep the maximum value seen so far.
-</details>
diff --git a/problems/replace-employee-id-with-the-unique-identifier/README.md b/problems/replace-employee-id-with-the-unique-identifier/README.md
deleted file mode 100644
index ab56752eb..000000000
--- a/problems/replace-employee-id-with-the-unique-identifier/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../frog-position-after-t-seconds "Frog Position After T Seconds")
-　　　　　　　　　　　　　　　　
-[Next >](../find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree "Find a Corresponding Node of a Binary Tree in a Clone of That Tree")
-
-## [1378. Replace Employee ID With The Unique Identifier (Easy)](https://leetcode.com/problems/replace-employee-id-with-the-unique-identifier "使用唯一标识码替换员工ID")
-
-<p>Table: <code>Employees</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| name          | varchar |
-+---------------+---------+
-id is the primary key for this table.
-Each row of this table contains the id and the name of an employee in a company.
-</pre>
- 
-<p>Table: <code>EmployeeUNI</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| unique_id     | int     |
-+---------------+---------+
-(id, unique_id) is the primary key for this table.
-Each row of this table contains the id and the corresponding unique id of an employee in the company.
-</pre>
- 
-Write an SQL query to show the unique ID of each user, If a user doesn't have a unique ID replace just show null.
-
-Return the result table in any order.
-
-The query result format is in the following example:
-<pre>
-Employees table:
-+----+----------+
-| id | name     |
-+----+----------+
-| 1  | Alice    |
-| 7  | Bob      |
-| 11 | Meir     |
-| 90 | Winston  |
-| 3  | Jonathan |
-+----+----------+
-
-EmployeeUNI table:
-+----+-----------+
-| id | unique_id |
-+----+-----------+
-| 3  | 1         |
-| 11 | 2         |
-| 90 | 3         |
-+----+-----------+
-
-EmployeeUNI table:
-+-----------+----------+
-| unique_id | name     |
-+-----------+----------+
-| null      | Alice    |
-| null      | Bob      |
-| 2         | Meir     |
-| 3         | Winston  |
-| 1         | Jonathan |
-+-----------+----------+
-
-Alice and Bob don't have a unique ID, We will show null instead.
-The unique ID of Meir is 2.
-The unique ID of Winston is 3.
-The unique ID of Jonathan is 1.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/replace-employee-id-with-the-unique-identifier/mysql_schemas.sql b/problems/replace-employee-id-with-the-unique-identifier/mysql_schemas.sql
deleted file mode 100644
index 93fb4473d..000000000
--- a/problems/replace-employee-id-with-the-unique-identifier/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Employees (id int, name varchar(20));
-Create table If Not Exists EmployeeUNI (id int, unique_id int);
-Truncate table Employees;
-insert into Employees (id, name) values ('1', 'Alice');
-insert into Employees (id, name) values ('7', 'Bob');
-insert into Employees (id, name) values ('11', 'Meir');
-insert into Employees (id, name) values ('90', 'Winston');
-insert into Employees (id, name) values ('3', 'Jonathan');
-Truncate table EmployeeUNI;
-insert into EmployeeUNI (id, unique_id) values ('3', '1');
-insert into EmployeeUNI (id, unique_id) values ('11', '2');
-insert into EmployeeUNI (id, unique_id) values ('90', '3');
diff --git a/problems/replace-the-substring-for-balanced-string/README.md b/problems/replace-the-substring-for-balanced-string/README.md
deleted file mode 100644
index dd661d977..000000000
--- a/problems/replace-the-substring-for-balanced-string/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-sub-folders-from-the-filesystem "Remove Sub-Folders from the Filesystem")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-profit-in-job-scheduling "Maximum Profit in Job Scheduling")
-
-## [1234. Replace the Substring for Balanced String (Medium)](https://leetcode.com/problems/replace-the-substring-for-balanced-string "替换子串得到平衡字符串")
-
-<p>You are given a string containing only 4&nbsp;kinds of characters <code>&#39;Q&#39;,</code> <code>&#39;W&#39;, &#39;E&#39;</code> and&nbsp;<code>&#39;R&#39;</code>.</p>
-
-<p>A string is said to be&nbsp;<strong>balanced</strong><em>&nbsp;</em>if each of its characters appears&nbsp;<code>n/4</code> times where <code>n</code> is the length of the string.</p>
-
-<p>Return the minimum length of the substring that can be replaced with <strong>any</strong> other string of the same length to make the original string <code>s</code>&nbsp;<strong>balanced</strong>.</p>
-
-<p>Return 0 if the string is already <strong>balanced</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;QWER&quot;
-<strong>Output:</strong> 0
-<strong>Explanation: </strong>s is already balanced.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;QQWE&quot;
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>We need to replace a &#39;Q&#39; to &#39;R&#39;, so that &quot;RQWE&quot; (or &quot;QRWE&quot;) is balanced.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;QQQW&quot;
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>We can replace the first &quot;QQ&quot; to &quot;ER&quot;. 
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;QQQQ&quot;
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>We can replace the last 3 &#39;Q&#39; to make s = &quot;QWER&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10^5</code></li>
-	<li><code>s.length</code> is a multiple of <code>4</code></li>
-	<li><code>s&nbsp;</code>contains only <code>&#39;Q&#39;</code>, <code>&#39;W&#39;</code>, <code>&#39;E&#39;</code> and&nbsp;<code>&#39;R&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use 2-pointers algorithm to make sure all amount of characters outside the 2 pointers are smaller or equal to n/4.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-That means you need to count the amount of each letter and make sure the amount is enough.
-</details>
diff --git a/problems/replace-words/README.md b/problems/replace-words/README.md
deleted file mode 100644
index d8c027369..000000000
--- a/problems/replace-words/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindromic-substrings "Palindromic Substrings")
-　　　　　　　　　　　　　　　　
-[Next >](../dota2-senate "Dota2 Senate")
-
-## [648. Replace Words (Medium)](https://leetcode.com/problems/replace-words "单词替换")
-
-<p>In English, we have a concept called <strong>root</strong>, which can be followed by some other word&nbsp;to form another longer word - let&#39;s call this word <strong>successor</strong>. For example, when the <strong>root</strong> <code>&quot;an&quot;</code> is&nbsp;followed by the <strong>successor</strong>&nbsp;word&nbsp;<code>&quot;other&quot;</code>, we&nbsp;can form a new word <code>&quot;another&quot;</code>.</p>
-
-<p>Given a <code>dictionary</code> consisting of many <strong>roots</strong> and a <code>sentence</code>&nbsp;consisting of words separated by spaces, replace all the <strong>successors</strong> in the sentence with the <strong>root</strong> forming it. If a <strong>successor</strong> can be replaced by more than one <strong>root</strong>,&nbsp;replace it with the <strong>root</strong> that has&nbsp;<strong>the shortest length</strong>.</p>
-
-<p>Return <em>the <code>sentence</code></em> after the replacement.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> dictionary = ["cat","bat","rat"], sentence = "the cattle was rattled by the battery"
-<strong>Output:</strong> "the cat was rat by the bat"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> dictionary = ["a","b","c"], sentence = "aadsfasf absbs bbab cadsfafs"
-<strong>Output:</strong> "a a b c"
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> dictionary = ["a", "aa", "aaa", "aaaa"], sentence = "a aa a aaaa aaa aaa aaa aaaaaa bbb baba ababa"
-<strong>Output:</strong> "a a a a a a a a bbb baba a"
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> dictionary = ["catt","cat","bat","rat"], sentence = "the cattle was rattled by the battery"
-<strong>Output:</strong> "the cat was rat by the bat"
-</pre><p><strong>Example 5:</strong></p>
-<pre><strong>Input:</strong> dictionary = ["ac","ab"], sentence = "it is abnormal that this solution is accepted"
-<strong>Output:</strong> "it is ab that this solution is ac"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= dictionary.length&nbsp;&lt;= 1000</code></li>
-	<li><code>1 &lt;= dictionary[i].length &lt;= 100</code></li>
-	<li><code>dictionary[i]</code>&nbsp;consists of only lower-case letters.</li>
-	<li><code>1 &lt;= sentence.length &lt;= 10^6</code></li>
-	<li><code>sentence</code>&nbsp;consists of only lower-case letters and spaces.</li>
-	<li>The number of words in&nbsp;<code>sentence</code>&nbsp;is in the range <code>[1, 1000]</code></li>
-	<li>The length of each word in&nbsp;<code>sentence</code>&nbsp;is in the range <code>[1, 1000]</code></li>
-	<li>Each two consecutive words in&nbsp;<code>sentence</code>&nbsp;will be separated by exactly one space.</li>
-	<li><code>sentence</code>&nbsp;does not have leading or trailing spaces.</li>
-</ul>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Implement Trie (Prefix Tree)](../implement-trie-prefix-tree) (Medium)
diff --git a/problems/replace-words/replace_words.go b/problems/replace-words/replace_words.go
deleted file mode 100644
index e57cf65f9..000000000
--- a/problems/replace-words/replace_words.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem648
diff --git a/problems/replace-words/replace_words_test.go b/problems/replace-words/replace_words_test.go
deleted file mode 100644
index e57cf65f9..000000000
--- a/problems/replace-words/replace_words_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem648
diff --git a/problems/report-contiguous-dates/README.md b/problems/report-contiguous-dates/README.md
deleted file mode 100644
index 8653cf4c4..000000000
--- a/problems/report-contiguous-dates/README.md
+++ /dev/null
@@ -1,94 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-equal-frequency "Maximum Equal Frequency")
-　　　　　　　　　　　　　　　　
-[Next >](../the-dining-philosophers "The Dining Philosophers")
-
-## [1225. Report Contiguous Dates (Hard)](https://leetcode.com/problems/report-contiguous-dates "报告系统状态的连续日期")
-
-<p>Table: <code>Failed</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| fail_date    | date    |
-+--------------+---------+
-Primary key for this table is fail_date.
-Failed table contains the days of failed tasks.
-</pre>
-
-<p>Table: <code>Succeeded</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| success_date | date    |
-+--------------+---------+
-Primary key for this table is success_date.
-Succeeded table contains the days of succeeded tasks.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>A system is running one task <strong>every day</strong>. Every task is independent of the previous tasks. The tasks can fail or succeed.</p>
-
-<p>Write an SQL query to generate a report of&nbsp;<code>period_state</code> for each continuous interval of days in the period from&nbsp;<strong>2019-01-01</strong> to <strong>2019-12-31</strong>.</p>
-
-<p><code>period_state</code> is <em>&#39;failed&#39;&nbsp;</em>if tasks in this interval failed or <em>&#39;succeeded&#39;</em>&nbsp;if tasks in this interval succeeded. Interval of days are retrieved as <code>start_date</code> and <code>end_date.</code></p>
-
-<p>Order result by <code>start_date</code>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Failed table:
-+-------------------+
-| fail_date         |
-+-------------------+
-| 2018-12-28        |
-| 2018-12-29        |
-| 2019-01-04        |
-| 2019-01-05        |
-+-------------------+
-
-Succeeded table:
-+-------------------+
-| success_date      |
-+-------------------+
-| 2018-12-30        |
-| 2018-12-31        |
-| 2019-01-01        |
-| 2019-01-02        |
-| 2019-01-03        |
-| 2019-01-06        |
-+-------------------+
-
-
-Result table:
-+--------------+--------------+--------------+
-| period_state | start date   | end date     |
-+--------------+--------------+--------------+
-| present      | 2019-01-01   | 2019-01-03   |
-| missing      | 2019-01-04   | 2019-01-05   |
-| present      | 2019-01-06   | 2019-01-06   |
-+--------------+--------------+--------------+
-
-The report ignored the system state in 2018 as we care about the system in the period 2019-01-01 to 2019-12-31.
-From 2019-01-01 to 2019-01-03 all tasks succeeded and the system state was &quot;present&quot;.
-From 2019-01-04 to 2019-01-05 all tasks failed and system state was &quot;missing&quot;.
-From 2019-01-06 to 2019-01-06 all tasks succeeded and system state was &quot;present&quot;.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Find the Start and End Number of Continuous Ranges](../find-the-start-and-end-number-of-continuous-ranges) (Medium)
-  1. [Find the Missing IDs](../find-the-missing-ids) (Medium)
diff --git a/problems/report-contiguous-dates/mysql_schemas.sql b/problems/report-contiguous-dates/mysql_schemas.sql
deleted file mode 100644
index 10a26648f..000000000
--- a/problems/report-contiguous-dates/mysql_schemas.sql
+++ /dev/null
@@ -1,14 +0,0 @@
-Create table If Not Exists Failed (fail_date date);
-Create table If Not Exists Succeeded (success_date date);
-Truncate table Failed;
-insert into Failed (fail_date) values ('2018-12-28');
-insert into Failed (fail_date) values ('2018-12-29');
-insert into Failed (fail_date) values ('2019-01-04');
-insert into Failed (fail_date) values ('2019-01-05');
-Truncate table Succeeded;
-insert into Succeeded (success_date) values ('2018-12-30');
-insert into Succeeded (success_date) values ('2018-12-31');
-insert into Succeeded (success_date) values ('2019-01-01');
-insert into Succeeded (success_date) values ('2019-01-02');
-insert into Succeeded (success_date) values ('2019-01-03');
-insert into Succeeded (success_date) values ('2019-01-06');
diff --git a/problems/reported-posts-ii/README.md b/problems/reported-posts-ii/README.md
deleted file mode 100644
index bd1a28b4e..000000000
--- a/problems/reported-posts-ii/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-of-absolute-value-expression "Maximum of Absolute Value Expression")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-unique-number "Largest Unique Number")
-
-## [1132. Reported Posts II (Medium)](https://leetcode.com/problems/reported-posts-ii "报告的记录 II")
-
-<p>Table: <code>Actions</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| user_id       | int     |
-| post_id       | int     |
-| action_date   | date    |
-| action        | enum    |
-| extra         | varchar |
-+---------------+---------+
-There is no primary key for this table, it may have duplicate rows.
-The action column is an ENUM type of (&#39;view&#39;, &#39;like&#39;, &#39;reaction&#39;, &#39;comment&#39;, &#39;report&#39;, &#39;share&#39;).
-The extra column has optional information about the action such as a reason for report or a type of reaction. </pre>
-
-<p>Table: <code>Removals</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| post_id       | int     |
-| remove_date   | date    | 
-+---------------+---------+
-post_id is the primary key of this table.
-Each row in this table indicates that some post was removed as a result of being reported or as a result of an admin review.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find the average for daily percentage&nbsp;of posts that got removed after being reported as spam,&nbsp;<strong>rounded to 2 decimal places</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Actions table:
-+---------+---------+-------------+--------+--------+
-| user_id | post_id | action_date | action | extra  |
-+---------+---------+-------------+--------+--------+
-| 1       | 1       | 2019-07-01  | view   | null   |
-| 1       | 1       | 2019-07-01  | like   | null   |
-| 1       | 1       | 2019-07-01  | share  | null   |
-| 2       | 2       | 2019-07-04  | view   | null   |
-| 2       | 2       | 2019-07-04  | report | spam   |
-| 3       | 4       | 2019-07-04  | view   | null   |
-| 3       | 4       | 2019-07-04  | report | spam   |
-| 4       | 3       | 2019-07-02  | view   | null   |
-| 4       | 3       | 2019-07-02  | report | spam   |
-| 5       | 2       | 2019-07-03  | view   | null   |
-| 5       | 2       | 2019-07-03  | report | racism |
-| 5       | 5       | 2019-07-03  | view   | null   |
-| 5       | 5       | 2019-07-03  | report | racism |
-+---------+---------+-------------+--------+--------+
-
-Removals table:
-+---------+-------------+
-| post_id | remove_date |
-+---------+-------------+
-| 2       | 2019-07-20  |
-| 3       | 2019-07-18  |
-+---------+-------------+
-
-Result table:
-+-----------------------+
-| average_daily_percent |
-+-----------------------+
-| 75.00                 |
-+-----------------------+
-The percentage for 2019-07-04 is 50% because only one post of two spam reported posts was removed.
-The percentage for 2019-07-02 is 100% because one post was reported as spam and it was removed.
-The other days had no spam reports so the average is (50 + 100) / 2 = 75%
-Note that the output is only one number and that we do not care about the remove dates.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/reported-posts-ii/mysql_schemas.sql b/problems/reported-posts-ii/mysql_schemas.sql
deleted file mode 100644
index 8b759ca9e..000000000
--- a/problems/reported-posts-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create table If Not Exists Actions (user_id int, post_id int, action_date date, action ENUM('view', 'like', 'reaction', 'comment', 'report', 'share'), extra varchar(10));
-create table if not exists Removals (post_id int, remove_date date);
-Truncate table Actions;
-insert into Actions (user_id, post_id, action_date, action, extra) values ('1', '1', '2019-07-01', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('1', '1', '2019-07-01', 'like', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('1', '1', '2019-07-01', 'share', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('2', '2', '2019-07-04', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('2', '2', '2019-07-04', 'report', 'spam');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('3', '4', '2019-07-04', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('3', '4', '2019-07-04', 'report', 'spam');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('4', '3', '2019-07-02', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('4', '3', '2019-07-02', 'report', 'spam');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('5', '2', '2019-07-03', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('5', '2', '2019-07-03', 'report', 'racism');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('5', '5', '2019-07-03', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('5', '5', '2019-07-03', 'report', 'racism');
-Truncate table Removals;
-insert into Removals (post_id, remove_date) values ('2', '2019-07-20');
-insert into Removals (post_id, remove_date) values ('3', '2019-07-18');
diff --git a/problems/reported-posts/README.md b/problems/reported-posts/README.md
deleted file mode 100644
index df69c7f59..000000000
--- a/problems/reported-posts/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../highest-grade-for-each-student "Highest Grade For Each Student")
-　　　　　　　　　　　　　　　　
-[Next >](../print-in-order "Print in Order")
-
-## [1113. Reported Posts (Easy)](https://leetcode.com/problems/reported-posts "报告的记录")
-
-<p>Table: <code>Actions</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| user_id       | int     |
-| post_id       | int     |
-| action_date   | date    | 
-| action        | enum    |
-| extra         | varchar |
-+---------------+---------+
-There is no primary key for this table, it may have duplicate rows.
-The action column is an ENUM type of (&#39;view&#39;, &#39;like&#39;, &#39;reaction&#39;, &#39;comment&#39;, &#39;report&#39;, &#39;share&#39;).
-The extra column has optional information about the action such as a reason for report or a type of reaction. </pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the number of posts reported yesterday for each report reason. Assume today is <strong>2019-07-05</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Actions table:
-+---------+---------+-------------+--------+--------+
-| user_id | post_id | action_date | action | extra  |
-+---------+---------+-------------+--------+--------+
-| 1       | 1       | 2019-07-01  | view   | null   |
-| 1       | 1       | 2019-07-01  | like   | null   |
-| 1       | 1       | 2019-07-01  | share  | null   |
-| 2       | 4       | 2019-07-04  | view   | null   |
-| 2       | 4       | 2019-07-04  | report | spam   |
-| 3       | 4       | 2019-07-04  | view   | null   |
-| 3       | 4       | 2019-07-04  | report | spam   |
-| 4       | 3       | 2019-07-02  | view   | null   |
-| 4       | 3       | 2019-07-02  | report | spam   |
-| 5       | 2       | 2019-07-04  | view   | null   |
-| 5       | 2       | 2019-07-04  | report | racism |
-| 5       | 5       | 2019-07-04  | view   | null   |
-| 5       | 5       | 2019-07-04  | report | racism |
-+---------+---------+-------------+--------+--------+
-
-Result table:
-+---------------+--------------+
-| report_reason | report_count |
-+---------------+--------------+
-| spam          | 1            |
-| racism        | 2            |
-+---------------+--------------+ 
-Note that we only care about report reasons with non zero number of reports.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/reported-posts/mysql_schemas.sql b/problems/reported-posts/mysql_schemas.sql
deleted file mode 100644
index 25a1cbc12..000000000
--- a/problems/reported-posts/mysql_schemas.sql
+++ /dev/null
@@ -1,15 +0,0 @@
-Create table If Not Exists Actions (user_id int, post_id int, action_date date, action ENUM('view', 'like', 'reaction', 'comment', 'report', 'share'), extra varchar(10));
-Truncate table Actions;
-insert into Actions (user_id, post_id, action_date, action, extra) values ('1', '1', '2019-07-01', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('1', '1', '2019-07-01', 'like', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('1', '1', '2019-07-01', 'share', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('2', '4', '2019-07-04', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('2', '4', '2019-07-04', 'report', 'spam');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('3', '4', '2019-07-04', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('3', '4', '2019-07-04', 'report', 'spam');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('4', '3', '2019-07-02', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('4', '3', '2019-07-02', 'report', 'spam');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('5', '2', '2019-07-04', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('5', '2', '2019-07-04', 'report', 'racism');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('5', '5', '2019-07-04', 'view', 'None');
-insert into Actions (user_id, post_id, action_date, action, extra) values ('5', '5', '2019-07-04', 'report', 'racism');
diff --git a/problems/reported-posts/reported_posts.sql b/problems/reported-posts/reported_posts.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/reported-posts/reported_posts.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/reshape-the-matrix/README.md b/problems/reshape-the-matrix/README.md
deleted file mode 100644
index f453ed4fa..000000000
--- a/problems/reshape-the-matrix/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../array-nesting "Array Nesting")
-　　　　　　　　　　　　　　　　
-[Next >](../permutation-in-string "Permutation in String")
-
-## [566. Reshape the Matrix (Easy)](https://leetcode.com/problems/reshape-the-matrix "重塑矩阵")
-
-<p>In MATLAB, there is a handy function called <code>reshape</code> which can reshape an <code>m x n</code> matrix into a new one with a different size <code>r x c</code> keeping its original data.</p>
-
-<p>You are given an <code>m x n</code> matrix <code>mat</code> and two integers <code>r</code> and <code>c</code> representing the number of rows and the number of columns of the wanted reshaped matrix.</p>
-
-<p>The reshaped matrix should be filled with all the elements of the original matrix in the same row-traversing order as they were.</p>
-
-<p>If the <code>reshape</code> operation with given parameters is possible and legal, output the new reshaped matrix; Otherwise, output the original matrix.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/reshape1-grid.jpg" style="width: 613px; height: 173px;" />
-<pre>
-<strong>Input:</strong> mat = [[1,2],[3,4]], r = 1, c = 4
-<strong>Output:</strong> [[1,2,3,4]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/reshape2-grid.jpg" style="width: 453px; height: 173px;" />
-<pre>
-<strong>Input:</strong> mat = [[1,2],[3,4]], r = 2, c = 4
-<strong>Output:</strong> [[1,2],[3,4]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li><code>-1000 &lt;= mat[i][j] &lt;= 1000</code></li>
-	<li><code>1 &lt;= r, c &lt;= 300</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do you know how 2d matrix is stored in 1d memory? Try to map 2-dimensions into one.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-M[i][j]=M[n*i+j] , where n is the number of cols. 
-This is the one way of converting 2-d indices into one 1-d index.  
-Now, how will you convert 1-d index into 2-d indices?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Try to use division and modulus to convert 1-d index into 2-d indices.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-M[i] =>  M[i/n][i%n] Will it result in right mapping? Take some example and check this formula.
-</details>
diff --git a/problems/reshape-the-matrix/reshape_the_matrix.go b/problems/reshape-the-matrix/reshape_the_matrix.go
deleted file mode 100644
index 1184b8242..000000000
--- a/problems/reshape-the-matrix/reshape_the_matrix.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem566
-
-func matrixReshape(nums [][]int, r int, c int) [][]int {
-	m, n := len(nums), len(nums[0])
-	if m*n != r*c {
-		return nums
-	}
-	ans := make([][]int, r)
-	for i := 0; i < r; i++ {
-		ans[i] = make([]int, c)
-	}
-	i, j := 0, 0
-	for _, row := range nums {
-		for _, v := range row {
-			ans[i][j] = v
-			if j++; j == c {
-				i++
-				j = 0
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/reshape-the-matrix/reshape_the_matrix_test.go b/problems/reshape-the-matrix/reshape_the_matrix_test.go
deleted file mode 100644
index 837868aa6..000000000
--- a/problems/reshape-the-matrix/reshape_the_matrix_test.go
+++ /dev/null
@@ -1,48 +0,0 @@
-package problem566
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	nums [][]int
-	r    int
-	c    int
-	want [][]int
-}
-
-func TestMatrixReshape(t *testing.T) {
-	tests := [...]testType{
-		{
-			nums: [][]int{
-				{1, 2},
-				{3, 4},
-			},
-			r: 1,
-			c: 4,
-			want: [][]int{
-				{1, 2, 3, 4},
-			},
-		},
-		{
-			nums: [][]int{
-				{1, 2},
-				{3, 4},
-			},
-			r: 2,
-			c: 4,
-			want: [][]int{
-				{1, 2},
-				{3, 4},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := matrixReshape(tt.nums, tt.r, tt.c)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.nums, got, tt.want)
-
-		}
-	}
-}
diff --git a/problems/restaurant-growth/README.md b/problems/restaurant-growth/README.md
deleted file mode 100644
index 4375bf834..000000000
--- a/problems/restaurant-growth/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-distance-to-type-a-word-using-two-fingers "Minimum Distance to Type a Word Using Two Fingers")
-　　　　　　　　　　　　　　　　
-[Next >](../ads-performance "Ads Performance")
-
-## [1321. Restaurant Growth (Medium)](https://leetcode.com/problems/restaurant-growth "餐馆营业额变化增长")
-
-<p>Table: <code>Customer</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| customer_id   | int     |
-| name          | varchar |
-| visited_on    | date    |
-| amount        | int     |
-+---------------+---------+
-(customer_id, visited_on) is the primary key for this table.
-This table contains data about customer transactions in a restaurant.
-visited_on is the date on which the customer with ID (customer_id) have visited the restaurant.
-amount is the total paid by a customer.
-</pre>
-
-You are the restaurant owner and you want to analyze a possible expansion (there will be at least one customer every day).
-
-Write an SQL query to compute moving average of how much customer paid in a 7 days window (current day + 6 days before) .
-
-The query result format is in the following example:
-
-Return result table ordered by visited_on.
-
-average_amount should be rounded to 2 decimal places, all dates are in the format ('YYYY-MM-DD').
-
-<pre>
-Customer table:
-+-------------+--------------+--------------+-------------+
-| customer_id | name         | visited_on   | amount      |
-+-------------+--------------+--------------+-------------+
-| 1           | Jhon         | 2019-01-01   | 100         |
-| 2           | Daniel       | 2019-01-02   | 110         |
-| 3           | Jade         | 2019-01-03   | 120         |
-| 4           | Khaled       | 2019-01-04   | 130         |
-| 5           | Winston      | 2019-01-05   | 110         | 
-| 6           | Elvis        | 2019-01-06   | 140         | 
-| 7           | Anna         | 2019-01-07   | 150         |
-| 8           | Maria        | 2019-01-08   | 80          |
-| 9           | Jaze         | 2019-01-09   | 110         | 
-| 1           | Jhon         | 2019-01-10   | 130         | 
-| 3           | Jade         | 2019-01-10   | 150         | 
-+-------------+--------------+--------------+-------------+
-
-Result table:
-+--------------+--------------+----------------+
-| visited_on   | amount       | average_amount |
-+--------------+--------------+----------------+
-| 2019-01-07   | 860          | 122.86         |
-| 2019-01-08   | 840          | 120            |
-| 2019-01-09   | 840          | 120            |
-| 2019-01-10   | 1000         | 142.86         |
-+--------------+--------------+----------------+
-
-1st moving average from 2019-01-01 to 2019-01-07 has an average_amount of (100 + 110 + 120 + 130 + 110 + 140 + 150)/7 = 122.86
-2nd moving average from 2019-01-02 to 2019-01-08 has an average_amount of (110 + 120 + 130 + 110 + 140 + 150 + 80)/7 = 120
-3rd moving average from 2019-01-03 to 2019-01-09 has an average_amount of (120 + 130 + 110 + 140 + 150 + 80 + 110)/7 = 120
-4th moving average from 2019-01-04 to 2019-01-10 has an average_amount of (130 + 110 + 140 + 150 + 80 + 110 + 130 + 150)/7 = 142.86
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/restaurant-growth/mysql_schemas.sql b/problems/restaurant-growth/mysql_schemas.sql
deleted file mode 100644
index 41462f500..000000000
--- a/problems/restaurant-growth/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Customer (customer_id int, name varchar(20), visited_on date, amount int);
-Truncate table Customer;
-insert into Customer (customer_id, name, visited_on, amount) values ('1', 'Jhon', '2019-01-01', '100');
-insert into Customer (customer_id, name, visited_on, amount) values ('2', 'Daniel', '2019-01-02', '110');
-insert into Customer (customer_id, name, visited_on, amount) values ('3', 'Jade', '2019-01-03', '120');
-insert into Customer (customer_id, name, visited_on, amount) values ('4', 'Khaled', '2019-01-04', '130');
-insert into Customer (customer_id, name, visited_on, amount) values ('5', 'Winston', '2019-01-05', '110');
-insert into Customer (customer_id, name, visited_on, amount) values ('6', 'Elvis', '2019-01-06', '140');
-insert into Customer (customer_id, name, visited_on, amount) values ('7', 'Anna', '2019-01-07', '150');
-insert into Customer (customer_id, name, visited_on, amount) values ('8', 'Maria', '2019-01-08', '80');
-insert into Customer (customer_id, name, visited_on, amount) values ('9', 'Jaze', '2019-01-09', '110');
-insert into Customer (customer_id, name, visited_on, amount) values ('1', 'Jhon', '2019-01-10', '130');
-insert into Customer (customer_id, name, visited_on, amount) values ('3', 'Jade', '2019-01-10', '150');
diff --git a/problems/restore-ip-addresses/README.md b/problems/restore-ip-addresses/README.md
deleted file mode 100644
index bb1747346..000000000
--- a/problems/restore-ip-addresses/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-linked-list-ii "Reverse Linked List II")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-inorder-traversal "Binary Tree Inorder Traversal")
-
-## [93. Restore IP Addresses (Medium)](https://leetcode.com/problems/restore-ip-addresses "复原 IP 地址")
-
-<p>A <strong>valid IP address</strong> consists of exactly four integers separated by single dots. Each integer is between <code>0</code> and <code>255</code> (<strong>inclusive</strong>) and cannot have leading zeros.</p>
-
-<ul>
-	<li>For example, <code>&quot;0.1.2.201&quot;</code> and <code>&quot;192.168.1.1&quot;</code> are <strong>valid</strong> IP addresses, but <code>&quot;0.011.255.245&quot;</code>, <code>&quot;192.168.1.312&quot;</code> and <code>&quot;192.168@1.1&quot;</code> are <strong>invalid</strong> IP addresses.</li>
-</ul>
-
-<p>Given a string <code>s</code> containing only digits, return <em>all possible valid IP addresses that can be formed by inserting dots into </em><code>s</code>. You are <strong>not</strong> allowed to reorder or remove any digits in <code>s</code>. You may return the valid IP addresses in <strong>any</strong> order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "25525511135"
-<strong>Output:</strong> ["255.255.11.135","255.255.111.35"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "0000"
-<strong>Output:</strong> ["0.0.0.0"]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s = "1111"
-<strong>Output:</strong> ["1.1.1.1"]
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> s = "010010"
-<strong>Output:</strong> ["0.10.0.10","0.100.1.0"]
-</pre><p><strong>Example 5:</strong></p>
-<pre><strong>Input:</strong> s = "101023"
-<strong>Output:</strong> ["1.0.10.23","1.0.102.3","10.1.0.23","10.10.2.3","101.0.2.3"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length &lt;= 20</code></li>
-	<li><code>s</code> consists of digits only.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [IP to CIDR](../ip-to-cidr) (Medium)
diff --git a/problems/restore-ip-addresses/restore_ip_addresses.go b/problems/restore-ip-addresses/restore_ip_addresses.go
deleted file mode 100644
index abc688137..000000000
--- a/problems/restore-ip-addresses/restore_ip_addresses.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem93
diff --git a/problems/restore-ip-addresses/restore_ip_addresses_test.go b/problems/restore-ip-addresses/restore_ip_addresses_test.go
deleted file mode 100644
index abc688137..000000000
--- a/problems/restore-ip-addresses/restore_ip_addresses_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem93
diff --git a/problems/restore-the-array-from-adjacent-pairs/README.md b/problems/restore-the-array-from-adjacent-pairs/README.md
deleted file mode 100644
index 8569f4741..000000000
--- a/problems/restore-the-array-from-adjacent-pairs/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-balls-in-a-box "Maximum Number of Balls in a Box")
-　　　　　　　　　　　　　　　　
-[Next >](../can-you-eat-your-favorite-candy-on-your-favorite-day "Can You Eat Your Favorite Candy on Your Favorite Day?")
-
-## [1743. Restore the Array From Adjacent Pairs (Medium)](https://leetcode.com/problems/restore-the-array-from-adjacent-pairs "从相邻元素对还原数组")
-
-<p>There is an integer array <code>nums</code> that consists of <code>n</code> <strong>unique </strong>elements, but you have forgotten it. However, you do remember every pair of adjacent elements in <code>nums</code>.</p>
-
-<p>You are given a 2D integer array <code>adjacentPairs</code> of size <code>n - 1</code> where each <code>adjacentPairs[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> indicates that the elements <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code> are adjacent in <code>nums</code>.</p>
-
-<p>It is guaranteed that every adjacent pair of elements <code>nums[i]</code> and <code>nums[i+1]</code> will exist in <code>adjacentPairs</code>, either as <code>[nums[i], nums[i+1]]</code> or <code>[nums[i+1], nums[i]]</code>. The pairs can appear <strong>in any order</strong>.</p>
-
-<p>Return <em>the original array </em><code>nums</code><em>. If there are multiple solutions, return <strong>any of them</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> adjacentPairs = [[2,1],[3,4],[3,2]]
-<strong>Output:</strong> [1,2,3,4]
-<strong>Explanation:</strong> This array has all its adjacent pairs in adjacentPairs.
-Notice that adjacentPairs[i] may not be in left-to-right order.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> adjacentPairs = [[4,-2],[1,4],[-3,1]]
-<strong>Output:</strong> [-2,4,1,-3]
-<strong>Explanation:</strong> There can be negative numbers.
-Another solution is [-3,1,4,-2], which would also be accepted.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> adjacentPairs = [[100000,-100000]]
-<strong>Output:</strong> [100000,-100000]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>nums.length == n</code></li>
-	<li><code>adjacentPairs.length == n - 1</code></li>
-	<li><code>adjacentPairs[i].length == 2</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i], u<sub>i</sub>, v<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-	<li>There exists some <code>nums</code> that has <code>adjacentPairs</code> as its pairs.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the first element of nums - it will only appear once in adjacentPairs.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The adjacent pairs are like edges of a graph. Perform a depth-first search from the first element.
-</details>
diff --git a/problems/restore-the-array/README.md b/problems/restore-the-array/README.md
deleted file mode 100644
index caa50f9a9..000000000
--- a/problems/restore-the-array/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-k-th-lexicographical-string-of-all-happy-strings-of-length-n "The k-th Lexicographical String of All Happy Strings of Length n")
-　　　　　　　　　　　　　　　　
-[Next >](../reformat-the-string "Reformat The String")
-
-## [1416. Restore The Array (Hard)](https://leetcode.com/problems/restore-the-array "恢复数组")
-
-<p>A program was supposed to print an array of integers. The program forgot to print whitespaces and the array is printed as a string of digits <code>s</code> and all we know is that all integers in the array were in the range <code>[1, k]</code> and there are no leading zeros in the array.</p>
-
-<p>Given the string <code>s</code> and the integer <code>k</code>, return <em>the number of the possible arrays that can be printed as </em><code>s</code><em> using the mentioned program</em>. Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1000&quot;, k = 10000
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only possible array is [1000]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1000&quot;, k = 10
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There cannot be an array that was printed this way and has all integer &gt;= 1 and &lt;= 10.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1317&quot;, k = 2000
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> Possible arrays are [1317],[131,7],[13,17],[1,317],[13,1,7],[1,31,7],[1,3,17],[1,3,1,7]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of only digits and does not contain leading zeros.</li>
-	<li><code>1 &lt;= k &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Number of Ways to Separate Numbers](../number-of-ways-to-separate-numbers) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming. Build an array dp where dp[i] is the number of ways you can divide the string starting from index i to the end.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep in mind that the answer is modulo 10^9 + 7 and take the mod for each operation.
-</details>
diff --git a/problems/reveal-cards-in-increasing-order/README.md b/problems/reveal-cards-in-increasing-order/README.md
deleted file mode 100644
index 8250a5d91..000000000
--- a/problems/reveal-cards-in-increasing-order/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-time-for-given-digits "Largest Time for Given Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../flip-equivalent-binary-trees "Flip Equivalent Binary Trees")
-
-## [950. Reveal Cards In Increasing Order (Medium)](https://leetcode.com/problems/reveal-cards-in-increasing-order "按递增顺序显示卡牌")
-
-<p>You are given an integer array <code>deck</code>. There is a deck of cards where every card has a unique integer. The integer on the <code>i<sup>th</sup></code> card is <code>deck[i]</code>.</p>
-
-<p>You can order the deck in any order you want. Initially, all the cards start face down (unrevealed) in one deck.</p>
-
-<p>You will do the following steps repeatedly until all cards are revealed:</p>
-
-<ol>
-	<li>Take the top card of the deck, reveal it, and take it out of the deck.</li>
-	<li>If there are still cards in the deck then put the next top card of the deck at the bottom of the deck.</li>
-	<li>If there are still unrevealed cards, go back to step 1. Otherwise, stop.</li>
-</ol>
-
-<p>Return <em>an ordering of the deck that would reveal the cards in increasing order</em>.</p>
-
-<p><strong>Note</strong> that the first entry in the answer is considered to be the top of the deck.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> deck = [17,13,11,2,3,5,7]
-<strong>Output:</strong> [2,13,3,11,5,17,7]
-<strong>Explanation:</strong> 
-We get the deck in the order [17,13,11,2,3,5,7] (this order does not matter), and reorder it.
-After reordering, the deck starts as [2,13,3,11,5,17,7], where 2 is the top of the deck.
-We reveal 2, and move 13 to the bottom.  The deck is now [3,11,5,17,7,13].
-We reveal 3, and move 11 to the bottom.  The deck is now [5,17,7,13,11].
-We reveal 5, and move 17 to the bottom.  The deck is now [7,13,11,17].
-We reveal 7, and move 13 to the bottom.  The deck is now [11,17,13].
-We reveal 11, and move 17 to the bottom.  The deck is now [13,17].
-We reveal 13, and move 17 to the bottom.  The deck is now [17].
-We reveal 17.
-Since all the cards revealed are in increasing order, the answer is correct.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> deck = [1,1000]
-<strong>Output:</strong> [1,1000]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= deck.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= deck[i] &lt;= 10<sup>6</sup></code></li>
-	<li>All the values of <code>deck</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/reveal-cards-in-increasing-order/reveal_cards_in_increasing_order.go b/problems/reveal-cards-in-increasing-order/reveal_cards_in_increasing_order.go
deleted file mode 100644
index de9e26e17..000000000
--- a/problems/reveal-cards-in-increasing-order/reveal_cards_in_increasing_order.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem950
diff --git a/problems/reveal-cards-in-increasing-order/reveal_cards_in_increasing_order_test.go b/problems/reveal-cards-in-increasing-order/reveal_cards_in_increasing_order_test.go
deleted file mode 100644
index de9e26e17..000000000
--- a/problems/reveal-cards-in-increasing-order/reveal_cards_in_increasing_order_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem950
diff --git a/problems/reverse-bits/README.md b/problems/reverse-bits/README.md
deleted file mode 100644
index 37efcfc69..000000000
--- a/problems/reverse-bits/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rotate-array "Rotate Array")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-1-bits "Number of 1 Bits")
-
-## [190. Reverse Bits (Easy)](https://leetcode.com/problems/reverse-bits "颠倒二进制位")
-
-<p>Reverse bits of a given 32 bits unsigned integer.</p>
-
-<p><strong>Note:</strong></p>
-
-<ul>
-	<li>Note that in some languages, such as Java, there is no unsigned integer type. In this case, both input and output will be given as a signed integer type. They should not affect your implementation, as the integer&#39;s internal binary representation is the same, whether it is signed or unsigned.</li>
-	<li>In Java, the compiler represents the signed integers using <a href="https://en.wikipedia.org/wiki/Two%27s_complement" target="_blank">2&#39;s complement notation</a>. Therefore, in <strong>Example 2</strong> above, the input represents the signed integer <code>-3</code> and the output represents the signed integer <code>-1073741825</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 00000010100101000001111010011100
-<strong>Output:</strong>    964176192 (00111001011110000010100101000000)
-<strong>Explanation: </strong>The input binary string <strong>00000010100101000001111010011100</strong> represents the unsigned integer 43261596, so return 964176192 which its binary representation is <strong>00111001011110000010100101000000</strong>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 11111111111111111111111111111101
-<strong>Output:</strong>   3221225471 (10111111111111111111111111111111)
-<strong>Explanation: </strong>The input binary string <strong>11111111111111111111111111111101</strong> represents the unsigned integer 4294967293, so return 3221225471 which its binary representation is <strong>10111111111111111111111111111111</strong>.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The input must be a <strong>binary string</strong> of length <code>32</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> If this function is called many times, how would you optimize it?</p>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-
-### Similar Questions
-  1. [Reverse Integer](../reverse-integer) (Medium)
-  1. [Number of 1 Bits](../number-of-1-bits) (Easy)
diff --git a/problems/reverse-bits/reverse_bits.go b/problems/reverse-bits/reverse_bits.go
deleted file mode 100644
index 4d3f0f2e3..000000000
--- a/problems/reverse-bits/reverse_bits.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem190
-
-import "math/bits"
-
-func reverseBits(num uint32) uint32 {
-	return bits.Reverse32(num)
-}
diff --git a/problems/reverse-bits/reverse_bits_test.go b/problems/reverse-bits/reverse_bits_test.go
deleted file mode 100644
index 827efc5c6..000000000
--- a/problems/reverse-bits/reverse_bits_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem190
-
-import "testing"
-
-type testType struct {
-	in   uint32
-	want uint32
-}
-
-func TestReverseBits(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   43261596,
-			want: 964176192,
-		},
-		{
-			in:   4294967293,
-			want: 3221225471,
-		},
-	}
-	for _, tt := range tests {
-		got := reverseBits(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/reverse-integer/README.md b/problems/reverse-integer/README.md
deleted file mode 100644
index 6a50b5bed..000000000
--- a/problems/reverse-integer/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../zigzag-conversion "Zigzag Conversion")
-　　　　　　　　　　　　　　　　
-[Next >](../string-to-integer-atoi "String to Integer (atoi)")
-
-## [7. Reverse Integer (Medium)](https://leetcode.com/problems/reverse-integer "整数反转")
-
-<p>Given a signed 32-bit integer <code>x</code>, return <code>x</code><em> with its digits reversed</em>. If reversing <code>x</code> causes the value to go outside the signed 32-bit integer range <code>[-2<sup>31</sup>, 2<sup>31</sup> - 1]</code>, then return <code>0</code>.</p>
-
-<p><strong>Assume the environment does not allow you to store 64-bit integers (signed or unsigned).</strong></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> x = 123
-<strong>Output:</strong> 321
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> x = -123
-<strong>Output:</strong> -321
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> x = 120
-<strong>Output:</strong> 21
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> x = 0
-<strong>Output:</strong> 0
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= x &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [String to Integer (atoi)](../string-to-integer-atoi) (Medium)
-  1. [Reverse Bits](../reverse-bits) (Easy)
diff --git a/problems/reverse-integer/reverse_integer.go b/problems/reverse-integer/reverse_integer.go
deleted file mode 100644
index e624a2578..000000000
--- a/problems/reverse-integer/reverse_integer.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem7
-
-import "math"
-
-func reverse(x int) int {
-	r := 0
-	for x != 0 {
-		r = r*10 + x%10
-		if r > math.MaxInt32 || r < math.MinInt32 {
-			return 0
-		}
-		x /= 10
-	}
-	return r
-}
diff --git a/problems/reverse-integer/reverse_integer_test.go b/problems/reverse-integer/reverse_integer_test.go
deleted file mode 100644
index 1d20103c0..000000000
--- a/problems/reverse-integer/reverse_integer_test.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem7
-
-import (
-	"math"
-	"testing"
-)
-
-func TestReverse(t *testing.T) {
-	tests := map[int]int{
-		123:           321,
-		-123:          -321,
-		120:           21,
-		math.MaxInt32: 0,
-		math.MinInt32: 0,
-	}
-
-	for in, want := range tests {
-		got := reverse(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/reverse-linked-list-ii/README.md b/problems/reverse-linked-list-ii/README.md
deleted file mode 100644
index e348ad947..000000000
--- a/problems/reverse-linked-list-ii/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decode-ways "Decode Ways")
-　　　　　　　　　　　　　　　　
-[Next >](../restore-ip-addresses "Restore IP Addresses")
-
-## [92. Reverse Linked List II (Medium)](https://leetcode.com/problems/reverse-linked-list-ii "反转链表 II")
-
-<p>Given the <code>head</code> of a singly linked list and two integers <code>left</code> and <code>right</code> where <code>left &lt;= right</code>, reverse the nodes of the list from position <code>left</code> to position <code>right</code>, and return <em>the reversed list</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/rev2ex2.jpg" style="width: 542px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5], left = 2, right = 4
-<strong>Output:</strong> [1,4,3,2,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [5], left = 1, right = 1
-<strong>Output:</strong> [5]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is <code>n</code>.</li>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-	<li><code>-500 &lt;= Node.val &lt;= 500</code></li>
-	<li><code>1 &lt;= left &lt;= right &lt;= n</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you do it in one pass?
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Reverse Linked List](../reverse-linked-list) (Easy)
diff --git a/problems/reverse-linked-list-ii/reverse_linked_list_ii.go b/problems/reverse-linked-list-ii/reverse_linked_list_ii.go
deleted file mode 100644
index d62c62485..000000000
--- a/problems/reverse-linked-list-ii/reverse_linked_list_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem92
diff --git a/problems/reverse-linked-list-ii/reverse_linked_list_ii_test.go b/problems/reverse-linked-list-ii/reverse_linked_list_ii_test.go
deleted file mode 100644
index d62c62485..000000000
--- a/problems/reverse-linked-list-ii/reverse_linked_list_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem92
diff --git a/problems/reverse-linked-list/README.md b/problems/reverse-linked-list/README.md
deleted file mode 100644
index be9956cae..000000000
--- a/problems/reverse-linked-list/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../isomorphic-strings "Isomorphic Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../course-schedule "Course Schedule")
-
-## [206. Reverse Linked List (Easy)](https://leetcode.com/problems/reverse-linked-list "反转链表")
-
-<p>Given the <code>head</code> of a singly linked list, reverse the list, and return <em>the reversed list</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/rev1ex1.jpg" style="width: 542px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5]
-<strong>Output:</strong> [5,4,3,2,1]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/rev1ex2.jpg" style="width: 182px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,2]
-<strong>Output:</strong> [2,1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is the range <code>[0, 5000]</code>.</li>
-	<li><code>-5000 &lt;= Node.val &lt;= 5000</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> A linked list can be reversed either iteratively or recursively. Could you implement both?</p>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-
-### Similar Questions
-  1. [Reverse Linked List II](../reverse-linked-list-ii) (Medium)
-  1. [Binary Tree Upside Down](../binary-tree-upside-down) (Medium)
-  1. [Palindrome Linked List](../palindrome-linked-list) (Easy)
-  1. [Reverse Nodes in Even Length Groups](../reverse-nodes-in-even-length-groups) (Medium)
-  1. [Maximum Twin Sum of a Linked List](../maximum-twin-sum-of-a-linked-list) (Medium)
diff --git a/problems/reverse-linked-list/reverse_linked_list.go b/problems/reverse-linked-list/reverse_linked_list.go
deleted file mode 100644
index d46a6bf54..000000000
--- a/problems/reverse-linked-list/reverse_linked_list.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem206
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// ListNode - Definition for singly-linked list.
-type ListNode = kit.ListNode
-
-/**
- * Definition for singly-linked list.
- * type ListNode struct {
- *     Val int
- *     Next *ListNode
- * }
- */
-func reverseList(head *ListNode) *ListNode {
-	var pre *ListNode
-	for head != nil {
-		pre, head, head.Next = head, head.Next, pre
-	}
-	return pre
-}
diff --git a/problems/reverse-linked-list/reverse_linked_list_test.go b/problems/reverse-linked-list/reverse_linked_list_test.go
deleted file mode 100644
index 47f5c2046..000000000
--- a/problems/reverse-linked-list/reverse_linked_list_test.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package problem206
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestReverseList(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3, 4, 5},
-			want: []int{5, 4, 3, 2, 1},
-		},
-	}
-	for _, tt := range tests {
-		got := kit.ListNode2SliceInt(reverseList(kit.SliceInt2ListNode(tt.in)))
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/reverse-nodes-in-even-length-groups/README.md b/problems/reverse-nodes-in-even-length-groups/README.md
deleted file mode 100644
index ff39ee8c6..000000000
--- a/problems/reverse-nodes-in-even-length-groups/README.md
+++ /dev/null
@@ -1,103 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../time-needed-to-buy-tickets "Time Needed to Buy Tickets")
-　　　　　　　　　　　　　　　　
-[Next >](../decode-the-slanted-ciphertext "Decode the Slanted Ciphertext")
-
-## [2074. Reverse Nodes in Even Length Groups (Medium)](https://leetcode.com/problems/reverse-nodes-in-even-length-groups "反转偶数长度组的节点")
-
-<p>You are given the <code>head</code> of a linked list.</p>
-
-<p>The nodes in the linked list are <strong>sequentially</strong> assigned to <strong>non-empty</strong> groups whose lengths form the sequence of the natural numbers (<code>1, 2, 3, 4, ...</code>). The <strong>length</strong> of a group is the number of nodes assigned to it. In other words,</p>
-
-<ul>
-	<li>The <code>1<sup>st</sup></code> node is assigned to the first group.</li>
-	<li>The <code>2<sup>nd</sup></code> and the <code>3<sup>rd</sup></code> nodes are assigned to the second group.</li>
-	<li>The <code>4<sup>th</sup></code>, <code>5<sup>th</sup></code>, and <code>6<sup>th</sup></code> nodes are assigned to the third group, and so on.</li>
-</ul>
-
-<p>Note that the length of the last group may be less than or equal to <code>1 + the length of the second to last group</code>.</p>
-
-<p><strong>Reverse</strong> the nodes in each group with an <strong>even</strong> length, and return <em>the</em> <code>head</code> <em>of the modified linked list</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/25/eg1.png" style="width: 699px; height: 124px;" />
-<pre>
-<strong>Input:</strong> head = [5,2,6,3,9,1,7,3,8,4]
-<strong>Output:</strong> [5,6,2,3,9,1,4,8,3,7]
-<strong>Explanation:</strong>
-- The length of the first group is 1, which is odd, hence no reversal occurs.
-- The length of the second group is 2, which is even, hence the nodes are reversed.
-- The length of the third group is 3, which is odd, hence no reversal occurs.
-- The length of the last group is 4, which is even, hence the nodes are reversed.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/25/eg2.png" style="width: 284px; height: 114px;" />
-<pre>
-<strong>Input:</strong> head = [1,1,0,6]
-<strong>Output:</strong> [1,0,1,6]
-<strong>Explanation:</strong>
-- The length of the first group is 1. No reversal occurs.
-- The length of the second group is 2. The nodes are reversed.
-- The length of the last group is 1. No reversal occurs.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/17/ex3.png" style="width: 348px; height: 114px;" />
-<pre>
-<strong>Input:</strong> head = [1,1,0,6,5]
-<strong>Output:</strong> [1,0,1,5,6]
-<strong>Explanation:</strong>
-- The length of the first group is 1. No reversal occurs.
-- The length of the second group is 2. The nodes are reversed.
-- The length of the last group is 2. The nodes are reversed.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider the list structure ...A → (B → ... → C) → D..., where the nodes between B and C (inclusive) form a group, A is the last node of the previous group, and D is the first node of the next group. How can you utilize this structure?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Suppose you have B → ... → C reversed (because it was of even length) so that it is now C → ... → B. What references do you need to fix so that the transitions between the previous, current, and next groups are correct?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-A.next should be set to C, and B.next should be set to D.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Once the current group is finished being modified, you need to find the new A, B, C, and D nodes for the next group. How can you use the old A, B, C, and D nodes to find the new ones?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-The new A is either the old B or old C depending on if the group was of even or odd length. The new B is always the old D. The new C and D can be found based on the new B and the next group's length.
-</details>
-
-<details>
-<summary>Hint 6</summary>
-You can set the initial values of A, B, C, and D to A = null, B = head, C = head, D = head.next. Repeat the steps from the previous hints until D is null.
-</details>
diff --git a/problems/reverse-nodes-in-k-group/README.md b/problems/reverse-nodes-in-k-group/README.md
deleted file mode 100644
index 7ad436a04..000000000
--- a/problems/reverse-nodes-in-k-group/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../swap-nodes-in-pairs "Swap Nodes in Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-duplicates-from-sorted-array "Remove Duplicates from Sorted Array")
-
-## [25. Reverse Nodes in k-Group (Hard)](https://leetcode.com/problems/reverse-nodes-in-k-group "K 个一组翻转链表")
-
-<p>Given a linked list, reverse the nodes of a linked list <em>k</em> at a time and return its modified list.</p>
-
-<p><em>k</em> is a positive integer and is less than or equal to the length of the linked list. If the number of nodes is not a multiple of <em>k</em> then left-out nodes, in the end, should remain as it is.</p>
-
-<p>You may&nbsp;not alter the values in the list&#39;s nodes, only nodes themselves may be changed.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/reverse_ex1.jpg" style="width: 542px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5], k = 2
-<strong>Output:</strong> [2,1,4,3,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/reverse_ex2.jpg" style="width: 542px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5], k = 3
-<strong>Output:</strong> [3,2,1,4,5]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5], k = 1
-<strong>Output:</strong> [1,2,3,4,5]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1], k = 1
-<strong>Output:</strong> [1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list&nbsp;is in the range <code>sz</code>.</li>
-	<li><code>1 &lt;= sz &lt;= 5000</code></li>
-	<li><code>0 &lt;= Node.val &lt;= 1000</code></li>
-	<li><code>1 &lt;= k &lt;= sz</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow-up:</strong> Can you solve the problem in O(1) extra memory space?
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Swap Nodes in Pairs](../swap-nodes-in-pairs) (Medium)
diff --git a/problems/reverse-nodes-in-k-group/reverse_nodes_in_k_group.go b/problems/reverse-nodes-in-k-group/reverse_nodes_in_k_group.go
deleted file mode 100644
index 32e3b6af1..000000000
--- a/problems/reverse-nodes-in-k-group/reverse_nodes_in_k_group.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem25
diff --git a/problems/reverse-nodes-in-k-group/reverse_nodes_in_k_group_test.go b/problems/reverse-nodes-in-k-group/reverse_nodes_in_k_group_test.go
deleted file mode 100644
index 32e3b6af1..000000000
--- a/problems/reverse-nodes-in-k-group/reverse_nodes_in_k_group_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem25
diff --git a/problems/reverse-only-letters/README.md b/problems/reverse-only-letters/README.md
deleted file mode 100644
index d614140f3..000000000
--- a/problems/reverse-only-letters/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-subsets "Word Subsets")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-sum-circular-subarray "Maximum Sum Circular Subarray")
-
-## [917. Reverse Only Letters (Easy)](https://leetcode.com/problems/reverse-only-letters "仅仅反转字母")
-
-<p>Given a string <code>s</code>, reverse the string according to the following rules:</p>
-
-<ul>
-	<li>All the characters that are not English letters remain in the same position.</li>
-	<li>All the English letters (lowercase or uppercase) should be reversed.</li>
-</ul>
-
-<p>Return <code>s</code><em> after reversing it</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "ab-cd"
-<strong>Output:</strong> "dc-ba"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "a-bC-dEf-ghIj"
-<strong>Output:</strong> "j-Ih-gfE-dCba"
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s = "Test1ng-Leet=code-Q!"
-<strong>Output:</strong> "Qedo1ct-eeLg=ntse-T!"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> consists of characters with ASCII values in the range <code>[33, 122]</code>.</li>
-	<li><code>s</code> does not contain <code>&#39;\&quot;&#39;</code> or <code>&#39;\\&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-This problem is exactly like reversing a normal string except that there are certain characters that we have to simply skip. That should be easy enough to do if you know how to reverse a string using the two-pointer approach.
-</details>
diff --git a/problems/reverse-only-letters/reverse_only_letters.go b/problems/reverse-only-letters/reverse_only_letters.go
deleted file mode 100644
index 8dc50ab80..000000000
--- a/problems/reverse-only-letters/reverse_only_letters.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem917
-
-import "unicode"
-
-func reverseOnlyLetters(S string) string {
-	s := []rune(S)
-	i, j := 0, len(s)-1
-	for i < j {
-		if !unicode.IsLetter(rune(S[i])) {
-			i++
-		} else if !unicode.IsLetter(rune(S[j])) {
-			j--
-		} else {
-			s[i], s[j] = s[j], s[i]
-			i++
-			j--
-		}
-	}
-	return string(s)
-}
diff --git a/problems/reverse-only-letters/reverse_only_letters_test.go b/problems/reverse-only-letters/reverse_only_letters_test.go
deleted file mode 100644
index 467e56dc8..000000000
--- a/problems/reverse-only-letters/reverse_only_letters_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem917
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestReverseOnlyLetters(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "ab-cd",
-			want: "dc-ba",
-		},
-		{
-			in:   "a-bC-dEf-ghIj",
-			want: "j-Ih-gfE-dCba",
-		},
-		{
-			in:   "Test1ng-Leet=code-Q!",
-			want: "Qedo1ct-eeLg=ntse-T!",
-		},
-	}
-	for _, tt := range tests {
-		got := reverseOnlyLetters(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/reverse-pairs/README.md b/problems/reverse-pairs/README.md
deleted file mode 100644
index ad153a41e..000000000
--- a/problems/reverse-pairs/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-the-rectangle "Construct the Rectangle")
-　　　　　　　　　　　　　　　　
-[Next >](../target-sum "Target Sum")
-
-## [493. Reverse Pairs (Hard)](https://leetcode.com/problems/reverse-pairs "翻转对")
-
-<p>Given an integer array <code>nums</code>, return <em>the number of <strong>reverse pairs</strong> in the array</em>.</p>
-
-<p>A reverse pair is a pair <code>(i, j)</code> where <code>0 &lt;= i &lt; j &lt; nums.length</code> and <code>nums[i] &gt; 2 * nums[j]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,3,2,3,1]
-<strong>Output:</strong> 2
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [2,4,3,5,1]
-<strong>Output:</strong> 3
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Merge Sort](../../tag/merge-sort/README.md)]
-
-### Similar Questions
-  1. [Count of Smaller Numbers After Self](../count-of-smaller-numbers-after-self) (Hard)
-  1. [Count of Range Sum](../count-of-range-sum) (Hard)
diff --git a/problems/reverse-pairs/reverse_pairs.go b/problems/reverse-pairs/reverse_pairs.go
deleted file mode 100644
index c85372a6c..000000000
--- a/problems/reverse-pairs/reverse_pairs.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem493
diff --git a/problems/reverse-pairs/reverse_pairs_test.go b/problems/reverse-pairs/reverse_pairs_test.go
deleted file mode 100644
index c85372a6c..000000000
--- a/problems/reverse-pairs/reverse_pairs_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem493
diff --git a/problems/reverse-prefix-of-word/README.md b/problems/reverse-prefix-of-word/README.md
deleted file mode 100644
index 37f9b97e9..000000000
--- a/problems/reverse-prefix-of-word/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-greater-multiple-made-of-two-digits "Smallest Greater Multiple Made of Two Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-pairs-of-interchangeable-rectangles "Number of Pairs of Interchangeable Rectangles")
-
-## [2000. Reverse Prefix of Word (Easy)](https://leetcode.com/problems/reverse-prefix-of-word "反转单词前缀")
-
-<p>Given a <strong>0-indexed</strong> string <code>word</code> and a character <code>ch</code>, <strong>reverse</strong> the segment of <code>word</code> that starts at index <code>0</code> and ends at the index of the <strong>first occurrence</strong> of <code>ch</code> (<strong>inclusive</strong>). If the character <code>ch</code> does not exist in <code>word</code>, do nothing.</p>
-
-<ul>
-	<li>For example, if <code>word = &quot;abcdefd&quot;</code> and <code>ch = &quot;d&quot;</code>, then you should <strong>reverse</strong> the segment that starts at <code>0</code> and ends at <code>3</code> (<strong>inclusive</strong>). The resulting string will be <code>&quot;<u>dcba</u>efd&quot;</code>.</li>
-</ul>
-
-<p>Return <em>the resulting string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;<u>abcd</u>efd&quot;, ch = &quot;d&quot;
-<strong>Output:</strong> &quot;<u>dcba</u>efd&quot;
-<strong>Explanation:</strong>&nbsp;The first occurrence of &quot;d&quot; is at index 3. 
-Reverse the part of word from 0 to 3 (inclusive), the resulting string is &quot;dcbaefd&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;<u>xyxz</u>xe&quot;, ch = &quot;z&quot;
-<strong>Output:</strong> &quot;<u>zxyx</u>xe&quot;
-<strong>Explanation:</strong>&nbsp;The first and only occurrence of &quot;z&quot; is at index 3.
-Reverse the part of word from 0 to 3 (inclusive), the resulting string is &quot;zxyxxe&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;abcd&quot;, ch = &quot;z&quot;
-<strong>Output:</strong> &quot;abcd&quot;
-<strong>Explanation:</strong>&nbsp;&quot;z&quot; does not exist in word.
-You should not do any reverse operation, the resulting string is &quot;abcd&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length &lt;= 250</code></li>
-	<li><code>word</code> consists of lowercase English letters.</li>
-	<li><code>ch</code> is a lowercase English letter.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the first index where ch appears.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find a way to reverse a substring of word.
-</details>
diff --git a/problems/reverse-string-ii/README.md b/problems/reverse-string-ii/README.md
deleted file mode 100644
index 0ae3f3651..000000000
--- a/problems/reverse-string-ii/README.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../single-element-in-a-sorted-array "Single Element in a Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../01-matrix "01 Matrix")
-
-## [541. Reverse String II (Easy)](https://leetcode.com/problems/reverse-string-ii "反转字符串 II")
-
-<p>Given a string <code>s</code> and an integer <code>k</code>, reverse the first <code>k</code> characters for every <code>2k</code> characters counting from the start of the string.</p>
-
-<p>If there are fewer than <code>k</code> characters left, reverse all of them. If there are less than <code>2k</code> but greater than or equal to <code>k</code> characters, then reverse the first <code>k</code> characters and left the other as original.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "abcdefg", k = 2
-<strong>Output:</strong> "bacdfeg"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "abcd", k = 2
-<strong>Output:</strong> "bacd"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-	<li><code>1 &lt;= k &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Reverse String](../reverse-string) (Easy)
-  1. [Reverse Words in a String III](../reverse-words-in-a-string-iii) (Easy)
diff --git a/problems/reverse-string-ii/reverse_string_ii.go b/problems/reverse-string-ii/reverse_string_ii.go
deleted file mode 100644
index 39535fc53..000000000
--- a/problems/reverse-string-ii/reverse_string_ii.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem541
-
-func reverseStr(s string, k int) string {
-	ss, l := []rune(s), len(s)-1
-	for i := 0; i < l; i += 2 * k {
-		for m, n := i, i+k-1; m < n; m, n = m+1, n-1 {
-			if n > l {
-				n = l
-			}
-			ss[m], ss[n] = ss[n], ss[m]
-		}
-	}
-	return string(ss)
-}
diff --git a/problems/reverse-string-ii/reverse_string_ii_test.go b/problems/reverse-string-ii/reverse_string_ii_test.go
deleted file mode 100644
index 5d58a0b8b..000000000
--- a/problems/reverse-string-ii/reverse_string_ii_test.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package problem541
-
-import "testing"
-
-type testType struct {
-	s    string
-	k    int
-	want string
-}
-
-func TestReverseStr(t *testing.T) {
-	tests := [...]testType{
-		{
-			s:    "abcdefg",
-			k:    2,
-			want: "bacdfeg",
-		},
-		{
-			s:    "abcdefg",
-			k:    4,
-			want: "dcbaefg",
-		},
-		{
-			s:    "abcd",
-			k:    4,
-			want: "dcba",
-		},
-		{
-			s:    "abcdefg",
-			k:    8,
-			want: "gfedcba",
-		},
-	}
-	for _, tt := range tests {
-		got := reverseStr(tt.s, tt.k)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.s, tt.k, got, tt.want)
-		}
-	}
-}
diff --git a/problems/reverse-string/README.md b/problems/reverse-string/README.md
deleted file mode 100644
index af5bd5a71..000000000
--- a/problems/reverse-string/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../integer-break "Integer Break")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-vowels-of-a-string "Reverse Vowels of a String")
-
-## [344. Reverse String (Easy)](https://leetcode.com/problems/reverse-string "反转字符串")
-
-<p>Write a function that reverses a string. The input string is given as an array of characters <code>s</code>.</p>
-
-<p>You must do this by modifying the input array <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank">in-place</a> with <code>O(1)</code> extra memory.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = ["h","e","l","l","o"]
-<strong>Output:</strong> ["o","l","l","e","h"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = ["H","a","n","n","a","h"]
-<strong>Output:</strong> ["h","a","n","n","a","H"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s[i]</code> is a <a href="https://en.wikipedia.org/wiki/ASCII#Printable_characters" target="_blank">printable ascii character</a>.</li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Reverse Vowels of a String](../reverse-vowels-of-a-string) (Easy)
-  1. [Reverse String II](../reverse-string-ii) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The entire logic for reversing a string is based on using the opposite directional two-pointer approach!
-</details>
diff --git a/problems/reverse-string/reverse_string.go b/problems/reverse-string/reverse_string.go
deleted file mode 100644
index 6afa50fe7..000000000
--- a/problems/reverse-string/reverse_string.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem344
-
-func reverseString(s []byte) {
-	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
-		s[i], s[j] = s[j], s[i]
-	}
-}
diff --git a/problems/reverse-string/reverse_string_test.go b/problems/reverse-string/reverse_string_test.go
deleted file mode 100644
index 67027e1e0..000000000
--- a/problems/reverse-string/reverse_string_test.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package problem344
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []byte
-	want []byte
-}
-
-func TestReverseString(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []byte{'h', 'e', 'l', 'l', 'o'},
-			want: []byte{'o', 'l', 'l', 'e', 'h'},
-		},
-		{
-			in:   []byte{'H', 'a', 'n', 'n', 'a', 'h'},
-			want: []byte{'h', 'a', 'n', 'n', 'a', 'H'},
-		},
-	}
-	for _, tt := range tests {
-		got := make([]byte, len(tt.in))
-		copy(got, tt.in)
-		reverseString(got)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/reverse-subarray-to-maximize-array-value/README.md b/problems/reverse-subarray-to-maximize-array-value/README.md
deleted file mode 100644
index 3ff6d629e..000000000
--- a/problems/reverse-subarray-to-maximize-array-value/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-the-matrix-diagonally "Sort the Matrix Diagonally")
-　　　　　　　　　　　　　　　　
-[Next >](../rank-transform-of-an-array "Rank Transform of an Array")
-
-## [1330. Reverse Subarray To Maximize Array Value (Hard)](https://leetcode.com/problems/reverse-subarray-to-maximize-array-value "翻转子数组得到最大的数组值")
-
-<p>You are given an integer array <code>nums</code>. The <em>value</em> of this array is defined as the sum of <code>|nums[i] - nums[i + 1]|</code> for all <code>0 &lt;= i &lt; nums.length - 1</code>.</p>
-
-<p>You are allowed to select any subarray of the given array and reverse it. You can perform this operation <strong>only once</strong>.</p>
-
-<p>Find maximum possible value of the final array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,1,5,4]
-<strong>Output:</strong> 10
-<b>Explanation: </b>By reversing the subarray [3,1,5] the array becomes [2,5,1,3,4] whose value is 10.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,4,9,24,2,1,10]
-<strong>Output:</strong> 68
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What's the score after reversing a sub-array [L, R] ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-It's the score without reversing it + abs(a[R] - a[L-1]) + abs(a[L] - a[R+1]) - abs(a[L] - a[L-1]) - abs(a[R] - a[R+1])
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How to maximize that formula given that abs(x - y) = max(x - y, y - x) ?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-This can be written as max(max(a[R] - a[L - 1], a[L - 1] - a[R]) + max(a[R + 1] - a[L], a[L] - a[R + 1]) - value(L) - value(R + 1)) over all L < R where value(i) = abs(a[i] - a[i-1])
-</details>
-
-<details>
-<summary>Hint 5</summary>
-This can be divided into 4 cases.
-</details>
diff --git a/problems/reverse-substrings-between-each-pair-of-parentheses/README.md b/problems/reverse-substrings-between-each-pair-of-parentheses/README.md
deleted file mode 100644
index b9b0748fe..000000000
--- a/problems/reverse-substrings-between-each-pair-of-parentheses/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-balloons "Maximum Number of Balloons")
-　　　　　　　　　　　　　　　　
-[Next >](../k-concatenation-maximum-sum "K-Concatenation Maximum Sum")
-
-## [1190. Reverse Substrings Between Each Pair of Parentheses (Medium)](https://leetcode.com/problems/reverse-substrings-between-each-pair-of-parentheses "反转每对括号间的子串")
-
-<p>You are given a string <code>s</code> that consists of lower case English letters and brackets.&nbsp;</p>
-
-<p>Reverse the strings&nbsp;in each&nbsp;pair of matching parentheses, starting&nbsp;from the innermost one.</p>
-
-<p>Your result should <strong>not</strong> contain any brackets.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(abcd)&quot;
-<strong>Output:</strong> &quot;dcba&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(u(love)i)&quot;
-<strong>Output:</strong> &quot;iloveu&quot;
-<strong>Explanation:</strong>&nbsp;The substring &quot;love&quot; is reversed first, then the whole string is reversed.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(ed(et(oc))el)&quot;
-<strong>Output:</strong> &quot;leetcode&quot;
-<strong>Explanation:</strong>&nbsp;First, we reverse the substring &quot;oc&quot;, then &quot;etco&quot;, and finally, the whole string.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a(bcdefghijkl(mno)p)q&quot;
-<strong>Output:</strong> &quot;apmnolkjihgfedcbq&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length &lt;= 2000</code></li>
-	<li><code>s</code> only contains lower case English characters and parentheses.</li>
-	<li>It&#39;s guaranteed that all parentheses are balanced.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find all brackets in the string.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Does the order of the reverse matter ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The order does not matter.
-</details>
diff --git a/problems/reverse-vowels-of-a-string/README.md b/problems/reverse-vowels-of-a-string/README.md
deleted file mode 100644
index cdc3e5937..000000000
--- a/problems/reverse-vowels-of-a-string/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-string "Reverse String")
-　　　　　　　　　　　　　　　　
-[Next >](../moving-average-from-data-stream "Moving Average from Data Stream")
-
-## [345. Reverse Vowels of a String (Easy)](https://leetcode.com/problems/reverse-vowels-of-a-string "反转字符串中的元音字母")
-
-<p>Given a string <code>s</code>, reverse only all the vowels in the string and return it.</p>
-
-<p>The vowels are <code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, and <code>&#39;u&#39;</code>, and they can appear in both cases.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "hello"
-<strong>Output:</strong> "holle"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "leetcode"
-<strong>Output:</strong> "leotcede"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 3 * 10<sup>5</sup></code></li>
-	<li><code>s</code> consist of <strong>printable ASCII</strong> characters.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Reverse String](../reverse-string) (Easy)
-  1. [Remove Vowels from a String](../remove-vowels-from-a-string) (Easy)
diff --git a/problems/reverse-vowels-of-a-string/reverse_vowels_of_a_string.go b/problems/reverse-vowels-of-a-string/reverse_vowels_of_a_string.go
deleted file mode 100644
index e7ab9cbab..000000000
--- a/problems/reverse-vowels-of-a-string/reverse_vowels_of_a_string.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem345
-
-func reverseVowels(s string) string {
-	i, j, ss := 0, len(s)-1, []byte(s)
-	for i < j {
-		if !isVowel(ss[i]) {
-			i++
-		} else if !isVowel(ss[j]) {
-			j--
-		} else {
-			ss[i], ss[j] = ss[j], ss[i]
-			i++
-			j--
-		}
-	}
-	return string(ss)
-}
-
-func isVowel(r byte) bool {
-	switch r {
-	case 'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U':
-		return true
-	}
-	return false
-}
diff --git a/problems/reverse-vowels-of-a-string/reverse_vowels_of_a_string_test.go b/problems/reverse-vowels-of-a-string/reverse_vowels_of_a_string_test.go
deleted file mode 100644
index 398aa3df7..000000000
--- a/problems/reverse-vowels-of-a-string/reverse_vowels_of_a_string_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem345
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestReverseVowels(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "hello",
-			want: "holle",
-		},
-		{
-			in:   "leetcode",
-			want: "leotcede",
-		},
-	}
-	for _, tt := range tests {
-		got := reverseVowels(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/reverse-words-in-a-string-ii/README.md b/problems/reverse-words-in-a-string-ii/README.md
deleted file mode 100644
index a3f5eff53..000000000
--- a/problems/reverse-words-in-a-string-ii/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../department-top-three-salaries "Department Top Three Salaries")
-　　　　　　　　　　　　　　　　
-[Next >](../repeated-dna-sequences "Repeated DNA Sequences")
-
-## [186. Reverse Words in a String II (Medium)](https://leetcode.com/problems/reverse-words-in-a-string-ii "翻转字符串里的单词 II")
-
-<p>Given an input string<strong><em>&nbsp;</em></strong>, reverse the string word by word.&nbsp;</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:  </strong>[&quot;t&quot;,&quot;h&quot;,&quot;e&quot;,&quot; &quot;,&quot;s&quot;,&quot;k&quot;,&quot;y&quot;,&quot; &quot;,&quot;i&quot;,&quot;s&quot;,&quot; &quot;,&quot;b&quot;,&quot;l&quot;,&quot;u&quot;,&quot;e&quot;]
-<strong>Output: </strong>[&quot;b&quot;,&quot;l&quot;,&quot;u&quot;,&quot;e&quot;,&quot; &quot;,&quot;i&quot;,&quot;s&quot;,&quot; &quot;,&quot;s&quot;,&quot;k&quot;,&quot;y&quot;,&quot; &quot;,&quot;t&quot;,&quot;h&quot;,&quot;e&quot;]</pre>
-
-<p><strong>Note:&nbsp;</strong></p>
-
-<ul>
-	<li>A word is defined as a sequence of non-space characters.</li>
-	<li>The input string does not contain leading or trailing spaces.</li>
-	<li>The words are always separated by a single space.</li>
-</ul>
-
-<p><strong>Follow up:&nbsp;</strong>Could you do it <i>in-place</i> without allocating extra space?</p>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Reverse Words in a String](../reverse-words-in-a-string) (Medium)
-  1. [Rotate Array](../rotate-array) (Medium)
diff --git a/problems/reverse-words-in-a-string-ii/reverse_words_in_a_string_ii.go b/problems/reverse-words-in-a-string-ii/reverse_words_in_a_string_ii.go
deleted file mode 100644
index ebd030477..000000000
--- a/problems/reverse-words-in-a-string-ii/reverse_words_in_a_string_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem186
diff --git a/problems/reverse-words-in-a-string-ii/reverse_words_in_a_string_ii_test.go b/problems/reverse-words-in-a-string-ii/reverse_words_in_a_string_ii_test.go
deleted file mode 100644
index ebd030477..000000000
--- a/problems/reverse-words-in-a-string-ii/reverse_words_in_a_string_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem186
diff --git a/problems/reverse-words-in-a-string-iii/README.md b/problems/reverse-words-in-a-string-iii/README.md
deleted file mode 100644
index 68b40c93c..000000000
--- a/problems/reverse-words-in-a-string-iii/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../next-greater-element-iii "Next Greater Element III")
-　　　　　　　　　　　　　　　　
-[Next >](../logical-or-of-two-binary-grids-represented-as-quad-trees "Logical OR of Two Binary Grids Represented as Quad-Trees")
-
-## [557. Reverse Words in a String III (Easy)](https://leetcode.com/problems/reverse-words-in-a-string-iii "反转字符串中的单词 III")
-
-<p>Given a string <code>s</code>, reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "Let's take LeetCode contest"
-<strong>Output:</strong> "s'teL ekat edoCteeL tsetnoc"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "God Ding"
-<strong>Output:</strong> "doG gniD"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>s</code> contains printable <strong>ASCII</strong> characters.</li>
-	<li><code>s</code> does not contain any leading or trailing spaces.</li>
-	<li>There is <strong>at least one</strong> word in <code>s</code>.</li>
-	<li>All the words in <code>s</code> are separated by a single space.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Reverse String II](../reverse-string-ii) (Easy)
diff --git a/problems/reverse-words-in-a-string-iii/reverse_words_in_a_string_iii.go b/problems/reverse-words-in-a-string-iii/reverse_words_in_a_string_iii.go
deleted file mode 100644
index f32cc2049..000000000
--- a/problems/reverse-words-in-a-string-iii/reverse_words_in_a_string_iii.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem557
-
-func reverseWords(s string) string {
-	ss, pre, l := []byte(s+" "), 0, len(s)
-	for cur, c := range ss {
-		if c == ' ' {
-			for i, j := pre, cur-1; i < j; i, j = i+1, j-1 {
-				ss[i], ss[j] = ss[j], ss[i]
-			}
-			pre = cur + 1
-		}
-	}
-	return string(ss[:l])
-}
diff --git a/problems/reverse-words-in-a-string-iii/reverse_words_in_a_string_iii_test.go b/problems/reverse-words-in-a-string-iii/reverse_words_in_a_string_iii_test.go
deleted file mode 100644
index 374779bab..000000000
--- a/problems/reverse-words-in-a-string-iii/reverse_words_in_a_string_iii_test.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem557
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestReverseWords(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "Let's take LeetCode contest",
-			want: "s'teL ekat edoCteeL tsetnoc",
-		},
-	}
-	for _, tt := range tests {
-		got := reverseWords(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/reverse-words-in-a-string/README.md b/problems/reverse-words-in-a-string/README.md
deleted file mode 100644
index 0a2002fd0..000000000
--- a/problems/reverse-words-in-a-string/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../evaluate-reverse-polish-notation "Evaluate Reverse Polish Notation")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-product-subarray "Maximum Product Subarray")
-
-## [151. Reverse Words in a String (Medium)](https://leetcode.com/problems/reverse-words-in-a-string "翻转字符串里的单词")
-
-<p>Given an input string <code>s</code>, reverse the order of the <strong>words</strong>.</p>
-
-<p>A <strong>word</strong> is defined as a sequence of non-space characters. The <strong>words</strong> in <code>s</code> will be separated by at least one space.</p>
-
-<p>Return <em>a string of the words in reverse order concatenated by a single space.</em></p>
-
-<p><b>Note</b> that <code>s</code> may contain leading or trailing spaces or multiple spaces between two words. The returned string should only have a single space separating the words. Do not include any extra spaces.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;the sky is blue&quot;
-<strong>Output:</strong> &quot;blue is sky the&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;  hello world  &quot;
-<strong>Output:</strong> &quot;world hello&quot;
-<strong>Explanation:</strong> Your reversed string should not contain leading or trailing spaces.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;a good   example&quot;
-<strong>Output:</strong> &quot;example good a&quot;
-<strong>Explanation:</strong> You need to reduce multiple spaces between two words to a single space in the reversed string.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> contains English letters (upper-case and lower-case), digits, and spaces <code>&#39; &#39;</code>.</li>
-	<li>There is <strong>at least one</strong> word in <code>s</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><b data-stringify-type="bold">Follow-up:&nbsp;</b>If the string data type is mutable in your language, can&nbsp;you solve it&nbsp;<b data-stringify-type="bold">in-place</b>&nbsp;with&nbsp;<code data-stringify-type="code">O(1)</code>&nbsp;extra space?</p>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Reverse Words in a String II](../reverse-words-in-a-string-ii) (Medium)
diff --git a/problems/reverse-words-in-a-string/reverse_words_in_a_string.go b/problems/reverse-words-in-a-string/reverse_words_in_a_string.go
deleted file mode 100644
index bc759673f..000000000
--- a/problems/reverse-words-in-a-string/reverse_words_in_a_string.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem151
-
-import (
-	"regexp"
-	"strings"
-)
-
-func reverseWords(s string) string {
-	reg := regexp.MustCompile(`\S+`)
-	words := reg.FindAllString(s, -1)
-	for i, j := 0, len(words)-1; i < j; i, j = i+1, j-1 {
-		words[i], words[j] = words[j], words[i]
-	}
-	return strings.Join(words, " ")
-}
diff --git a/problems/reverse-words-in-a-string/reverse_words_in_a_string_test.go b/problems/reverse-words-in-a-string/reverse_words_in_a_string_test.go
deleted file mode 100644
index a4038c9d2..000000000
--- a/problems/reverse-words-in-a-string/reverse_words_in_a_string_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem151
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestReverseWords(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "the sky is blue",
-			want: "blue is sky the",
-		},
-		{
-			in:   "  hello world!  ",
-			want: "world! hello",
-		},
-		{
-			in:   "a good   example",
-			want: "example good a",
-		},
-	}
-	for _, tt := range tests {
-		got := reverseWords(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/richest-customer-wealth/README.md b/problems/richest-customer-wealth/README.md
deleted file mode 100644
index b977f74c4..000000000
--- a/problems/richest-customer-wealth/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-removals-to-make-mountain-array "Minimum Number of Removals to Make Mountain Array")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-most-competitive-subsequence "Find the Most Competitive Subsequence")
-
-## [1672. Richest Customer Wealth (Easy)](https://leetcode.com/problems/richest-customer-wealth "最富有客户的资产总量")
-
-<p>You are given an <code>m x n</code> integer grid <code>accounts</code> where <code>accounts[i][j]</code> is the amount of money the <code>i​​​​​<sup>​​​​​​th</sup>​​​​</code> customer has in the <code>j​​​​​<sup>​​​​​​th</sup></code>​​​​ bank. Return<em> the <strong>wealth</strong> that the richest customer has.</em></p>
-
-<p>A customer&#39;s <strong>wealth</strong> is the amount of money they have in all their bank accounts. The richest customer is the customer that has the maximum <strong>wealth</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> accounts = [[1,2,3],[3,2,1]]
-<strong>Output:</strong> 6
-<strong>Explanation</strong><strong>:</strong>
-<code>1st customer has wealth = 1 + 2 + 3 = 6
-</code><code>2nd customer has wealth = 3 + 2 + 1 = 6
-</code>Both customers are considered the richest with a wealth of 6 each, so return 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> accounts = [[1,5],[7,3],[3,5]]
-<strong>Output:</strong> 10
-<strong>Explanation</strong>: 
-1st customer has wealth = 6
-2nd customer has wealth = 10 
-3rd customer has wealth = 8
-The 2nd customer is the richest with a wealth of 10.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> accounts = [[2,8,7],[7,1,3],[1,9,5]]
-<strong>Output:</strong> 17
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m ==&nbsp;accounts.length</code></li>
-	<li><code>n ==&nbsp;accounts[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 50</code></li>
-	<li><code>1 &lt;= accounts[i][j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Calculate the wealth of each customer
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the maximum element in array.
-</details>
diff --git a/problems/rings-and-rods/README.md b/problems/rings-and-rods/README.md
deleted file mode 100644
index 3944e5b9c..000000000
--- a/problems/rings-and-rods/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sequentially-ordinal-rank-tracker "Sequentially Ordinal Rank Tracker")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-subarray-ranges "Sum of Subarray Ranges")
-
-## [2103. Rings and Rods (Easy)](https://leetcode.com/problems/rings-and-rods "环和杆")
-
-<p>There are <code>n</code> rings and each ring is either red, green, or blue. The rings are distributed <strong>across ten rods</strong> labeled from <code>0</code> to <code>9</code>.</p>
-
-<p>You are given a string <code>rings</code> of length <code>2n</code> that describes the <code>n</code> rings that are placed onto the rods. Every two characters in <code>rings</code> forms a <strong>color-position pair</strong> that is used to describe each ring where:</p>
-
-<ul>
-	<li>The <strong>first</strong> character of the <code>i<sup>th</sup></code> pair denotes the <code>i<sup>th</sup></code> ring&#39;s <strong>color</strong> (<code>&#39;R&#39;</code>, <code>&#39;G&#39;</code>, <code>&#39;B&#39;</code>).</li>
-	<li>The <strong>second</strong> character of the <code>i<sup>th</sup></code> pair denotes the <strong>rod</strong> that the <code>i<sup>th</sup></code> ring is placed on (<code>&#39;0&#39;</code> to <code>&#39;9&#39;</code>).</li>
-</ul>
-
-<p>For example, <code>&quot;R3G2B1&quot;</code> describes <code>n == 3</code> rings: a red ring placed onto the rod labeled 3, a green ring placed onto the rod labeled 2, and a blue ring placed onto the rod labeled 1.</p>
-
-<p>Return <em>the number of rods that have <strong>all three colors</strong> of rings on them.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/23/ex1final.png" style="width: 258px; height: 130px;" />
-<pre>
-<strong>Input:</strong> rings = &quot;B0B6G0R6R0R6G9&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 
-- The rod labeled 0 holds 3 rings with all colors: red, green, and blue.
-- The rod labeled 6 holds 3 rings, but it only has red and blue.
-- The rod labeled 9 holds only a green ring.
-Thus, the number of rods with all three colors is 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/23/ex2final.png" style="width: 266px; height: 130px;" />
-<pre>
-<strong>Input:</strong> rings = &quot;B0R0G0R9R0B0G0&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 
-- The rod labeled 0 holds 6 rings with all colors: red, green, and blue.
-- The rod labeled 9 holds only a red ring.
-Thus, the number of rods with all three colors is 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> rings = &quot;G4&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> 
-Only one ring is given. Thus, no rods have all three colors.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>rings.length == 2 * n</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>rings[i]</code> where <code>i</code> is <strong>even</strong> is either <code>&#39;R&#39;</code>, <code>&#39;G&#39;</code>, or <code>&#39;B&#39;</code> (<strong>0-indexed</strong>).</li>
-	<li><code>rings[i]</code> where <code>i</code> is <strong>odd</strong> is a digit from <code>&#39;0&#39;</code> to <code>&#39;9&#39;</code> (<strong>0-indexed</strong>).</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For every rod, look through ‘rings’ to see if the rod contains all colors.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Create 3 booleans, 1 for each color, to store if that color is present for the current rod. If all 3 are true after looking through the string, then the rod contains all the colors.
-</details>
diff --git a/problems/rising-temperature/README.md b/problems/rising-temperature/README.md
deleted file mode 100644
index 8ec7df841..000000000
--- a/problems/rising-temperature/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-duplicate-emails "Delete Duplicate Emails")
-　　　　　　　　　　　　　　　　
-[Next >](../house-robber "House Robber")
-
-## [197. Rising Temperature (Easy)](https://leetcode.com/problems/rising-temperature "上升的温度")
-
-<p>Table: <code>Weather</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| recordDate    | date    |
-| temperature   | int     |
-+---------------+---------+
-id is the primary key for this table.
-This table contains information about the temperature in a certain day.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find all dates&#39; <code>id</code>&nbsp;with higher temperature compared to its previous dates (yesterday).</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-<code>Weather</code>
-+----+------------+-------------+
-| id | recordDate | Temperature |
-+----+------------+-------------+
-| 1  | 2015-01-01 | 10          |
-| 2  | 2015-01-02 | 25          |
-| 3  | 2015-01-03 | 20          |
-| 4  | 2015-01-04 | 30          |
-+----+------------+-------------+
-
-Result table:
-+----+
-| id |
-+----+
-| 2  |
-| 4  |
-+----+
-In 2015-01-02, temperature was higher than the previous day (10 -&gt; 25).
-In 2015-01-04, temperature was higher than the previous day (20 -&gt; 30).
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/rising-temperature/mysql_schemas.sql b/problems/rising-temperature/mysql_schemas.sql
deleted file mode 100644
index e6238f798..000000000
--- a/problems/rising-temperature/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Weather (Id int, RecordDate date, Temperature int);
-Truncate table Weather;
-insert into Weather (Id, RecordDate, Temperature) values ('1', '2015-01-01', '10');
-insert into Weather (Id, RecordDate, Temperature) values ('2', '2015-01-02', '25');
-insert into Weather (Id, RecordDate, Temperature) values ('3', '2015-01-03', '20');
-insert into Weather (Id, RecordDate, Temperature) values ('4', '2015-01-04', '30');
diff --git a/problems/rising-temperature/rising_temperature.sql b/problems/rising-temperature/rising_temperature.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/rising-temperature/rising_temperature.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/rle-iterator/README.md b/problems/rle-iterator/README.md
deleted file mode 100644
index 2ebd53cc0..000000000
--- a/problems/rle-iterator/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../orderly-queue "Orderly Queue")
-　　　　　　　　　　　　　　　　
-[Next >](../online-stock-span "Online Stock Span")
-
-## [900. RLE Iterator (Medium)](https://leetcode.com/problems/rle-iterator "RLE 迭代器")
-
-<p>We can use run-length encoding (i.e., <strong>RLE</strong>) to encode a sequence of integers. In a run-length encoded array of even length <code>encoding</code> (<strong>0-indexed</strong>), for all even <code>i</code>, <code>encoding[i]</code> tells us the number of times that the non-negative integer value <code>encoding[i + 1]</code> is repeated in the sequence.</p>
-
-<ul>
-	<li>For example, the sequence <code>arr = [8,8,8,5,5]</code> can be encoded to be <code>encoding = [3,8,2,5]</code>. <code>encoding = [3,8,0,9,2,5]</code> and <code>encoding = [2,8,1,8,2,5]</code> are also valid <strong>RLE</strong> of <code>arr</code>.</li>
-</ul>
-
-<p>Given a run-length encoded array, design an iterator that iterates through it.</p>
-
-<p>Implement the <code>RLEIterator</code> class:</p>
-
-<ul>
-	<li><code>RLEIterator(int[] encoded)</code> Initializes the object with the encoded array <code>encoded</code>.</li>
-	<li><code>int next(int n)</code> Exhausts the next <code>n</code> elements and returns the last element exhausted in this way. If there is no element left to exhaust, return <code>-1</code> instead.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;RLEIterator&quot;, &quot;next&quot;, &quot;next&quot;, &quot;next&quot;, &quot;next&quot;]
-[[[3, 8, 0, 9, 2, 5]], [2], [1], [1], [2]]
-<strong>Output</strong>
-[null, 8, 8, 5, -1]
-
-<strong>Explanation</strong>
-RLEIterator rLEIterator = new RLEIterator([3, 8, 0, 9, 2, 5]); // This maps to the sequence [8,8,8,5,5].
-rLEIterator.next(2); // exhausts 2 terms of the sequence, returning 8. The remaining sequence is now [8, 5, 5].
-rLEIterator.next(1); // exhausts 1 term of the sequence, returning 8. The remaining sequence is now [5, 5].
-rLEIterator.next(1); // exhausts 1 term of the sequence, returning 5. The remaining sequence is now [5].
-rLEIterator.next(2); // exhausts 2 terms, returning -1. This is because the first term exhausted was 5,
-but the second term did not exist. Since the last term exhausted does not exist, we return -1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= encoding.length &lt;= 1000</code></li>
-	<li><code>encoding.length</code> is even.</li>
-	<li><code>0 &lt;= encoding[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>1000</code> calls will be made to <code>next</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Iterator](../../tag/iterator/README.md)]
diff --git a/problems/rle-iterator/rle_iterator.go b/problems/rle-iterator/rle_iterator.go
deleted file mode 100644
index 9c344ef20..000000000
--- a/problems/rle-iterator/rle_iterator.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem900
diff --git a/problems/rle-iterator/rle_iterator_test.go b/problems/rle-iterator/rle_iterator_test.go
deleted file mode 100644
index 9c344ef20..000000000
--- a/problems/rle-iterator/rle_iterator_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem900
diff --git a/problems/robot-bounded-in-circle/README.md b/problems/robot-bounded-in-circle/README.md
deleted file mode 100644
index 7c7c71507..000000000
--- a/problems/robot-bounded-in-circle/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../moving-stones-until-consecutive-ii "Moving Stones Until Consecutive II")
-　　　　　　　　　　　　　　　　
-[Next >](../flower-planting-with-no-adjacent "Flower Planting With No Adjacent")
-
-## [1041. Robot Bounded In Circle (Medium)](https://leetcode.com/problems/robot-bounded-in-circle "困于环中的机器人")
-
-<p>On an infinite plane, a robot initially stands at <code>(0, 0)</code> and faces north. The robot can receive one of three instructions:</p>
-
-<ul>
-	<li><code>&quot;G&quot;</code>: go straight 1 unit;</li>
-	<li><code>&quot;L&quot;</code>: turn 90 degrees to the left;</li>
-	<li><code>&quot;R&quot;</code>: turn 90 degrees to the right.</li>
-</ul>
-
-<p>The robot performs the <code>instructions</code> given in order, and repeats them forever.</p>
-
-<p>Return <code>true</code> if and only if there exists a circle in the plane such that the robot never leaves the circle.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> instructions = &quot;GGLLGG&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The robot moves from (0,0) to (0,2), turns 180 degrees, and then returns to (0,0).
-When repeating these instructions, the robot remains in the circle of radius 2 centered at the origin.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> instructions = &quot;GG&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The robot moves north indefinitely.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> instructions = &quot;GL&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The robot moves from (0, 0) -&gt; (0, 1) -&gt; (-1, 1) -&gt; (-1, 0) -&gt; (0, 0) -&gt; ...</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= instructions.length &lt;= 100</code></li>
-	<li><code>instructions[i]</code> is <code>&#39;G&#39;</code>, <code>&#39;L&#39;</code> or, <code>&#39;R&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Calculate the final vector of how the robot travels after executing all instructions once - it consists of a change in position plus a change in direction.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The robot stays in the circle iff (looking at the final vector) it changes direction (ie. doesn't stay pointing north), or it moves 0.
-</details>
diff --git a/problems/robot-bounded-in-circle/robot_bounded_in_circle.go b/problems/robot-bounded-in-circle/robot_bounded_in_circle.go
deleted file mode 100644
index 4509b82f0..000000000
--- a/problems/robot-bounded-in-circle/robot_bounded_in_circle.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem1041
-
-func isRobotBounded(instructions string) bool {
-	x, y, dx, dy := 0, 0, 0, 1
-	for _, i := range instructions {
-		switch i {
-		case 'G':
-			x, y = x+dx, y+dy
-		case 'L':
-			dx, dy = -dy, dx
-		case 'R':
-			dx, dy = dy, -dx
-		}
-	}
-	return x == 0 && y == 0 || dx != 0 || dy != 1
-}
diff --git a/problems/robot-bounded-in-circle/robot_bounded_in_circle_test.go b/problems/robot-bounded-in-circle/robot_bounded_in_circle_test.go
deleted file mode 100644
index 94cf7a854..000000000
--- a/problems/robot-bounded-in-circle/robot_bounded_in_circle_test.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package problem1041
-
-import "testing"
-
-type testType struct {
-	in   string
-	want bool
-}
-
-func TestIsRobotBounded(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "GGLLGG",
-			want: true,
-		},
-		{
-			in:   "GG",
-			want: false,
-		},
-		{
-			in:   "GL",
-			want: true,
-		},
-		{
-			in:   "GGLLGGGGRRGG",
-			want: true,
-		},
-		{
-			in:   "GGRRGG",
-			want: true,
-		},
-		{
-			in:   "GLRLLGLL",
-			want: true,
-		},
-		{
-			in:   "GLGRGLGLGLGL",
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isRobotBounded(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/robot-return-to-origin/README.md b/problems/robot-return-to-origin/README.md
deleted file mode 100644
index c52e00567..000000000
--- a/problems/robot-return-to-origin/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../coin-path "Coin Path")
-　　　　　　　　　　　　　　　　
-[Next >](../find-k-closest-elements "Find K Closest Elements")
-
-## [657. Robot Return to Origin (Easy)](https://leetcode.com/problems/robot-return-to-origin "机器人能否返回原点")
-
-<p>There is a robot starting at the position <code>(0, 0)</code>, the origin, on a 2D plane. Given a sequence of its moves, judge if this robot <strong>ends up at </strong><code>(0, 0)</code> after it completes its moves.</p>
-
-<p>You are given a string <code>moves</code> that represents the move sequence of the robot where <code>moves[i]</code> represents its <code>i<sup>th</sup></code> move. Valid moves are <code>&#39;R&#39;</code> (right), <code>&#39;L&#39;</code> (left), <code>&#39;U&#39;</code> (up), and <code>&#39;D&#39;</code> (down).</p>
-
-<p>Return <code>true</code><em> if the robot returns to the origin after it finishes all of its moves, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p><strong>Note</strong>: The way that the robot is &quot;facing&quot; is irrelevant. <code>&#39;R&#39;</code> will always make the robot move to the right once, <code>&#39;L&#39;</code> will always make it move left, etc. Also, assume that the magnitude of the robot&#39;s movement is the same for each move.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> moves = &quot;UD&quot;
-<strong>Output:</strong> true
-<strong>Explanation</strong>: The robot moves up once, and then down once. All moves have the same magnitude, so it ended up at the origin where it started. Therefore, we return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> moves = &quot;LL&quot;
-<strong>Output:</strong> false
-<strong>Explanation</strong>: The robot moves left twice. It ends up two &quot;moves&quot; to the left of the origin. We return false because it is not at the origin at the end of its moves.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> moves = &quot;RRDD&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> moves = &quot;LDRRLRUULR&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= moves.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>moves</code> only contains the characters <code>&#39;U&#39;</code>, <code>&#39;D&#39;</code>, <code>&#39;L&#39;</code> and <code>&#39;R&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Number of Provinces](../number-of-provinces) (Medium)
diff --git a/problems/robot-return-to-origin/robot_return_to_origin.go b/problems/robot-return-to-origin/robot_return_to_origin.go
deleted file mode 100644
index a57224ec5..000000000
--- a/problems/robot-return-to-origin/robot_return_to_origin.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem657
-
-func judgeCircle(moves string) bool {
-	x, y := 0, 0
-	for _, move := range moves {
-		switch move {
-		case 'R':
-			x++
-		case 'L':
-			x--
-		case 'U':
-			y++
-		case 'D':
-			y--
-		}
-	}
-	return x == 0 && y == 0
-}
diff --git a/problems/robot-return-to-origin/robot_return_to_origin_test.go b/problems/robot-return-to-origin/robot_return_to_origin_test.go
deleted file mode 100644
index 46a9d5ced..000000000
--- a/problems/robot-return-to-origin/robot_return_to_origin_test.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package problem657
-
-import "testing"
-
-type testType struct {
-	in   string
-	want bool
-}
-
-func TestJudgeCircle(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "UD",
-			want: true,
-		},
-		{
-			in:   "RL",
-			want: true,
-		},
-		{
-			in:   "LL",
-			want: false,
-		},
-		{
-			in:   "UU",
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := judgeCircle(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
-
-func BenchmarkJudgeCircle(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		judgeCircle("RLUDRLUDRLUDRLUDRLUDRLUDRLUDRLUD")
-	}
-}
diff --git a/problems/robot-room-cleaner/README.md b/problems/robot-room-cleaner/README.md
deleted file mode 100644
index 8cdff14fe..000000000
--- a/problems/robot-room-cleaner/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../zuma-game "Zuma Game")
-　　　　　　　　　　　　　　　　
-[Next >](../the-maze "The Maze")
-
-## [489. Robot Room Cleaner (Hard)](https://leetcode.com/problems/robot-room-cleaner "扫地机器人")
-
-<p>Given a robot cleaner in a room modeled as a grid.</p>
-
-<p>Each cell in the grid can be empty or blocked.</p>
-
-<p>The robot cleaner with 4 given APIs can move forward, turn left or turn right. Each turn it made is 90 degrees.</p>
-
-<p>When it tries to move into a blocked cell, its bumper sensor detects the obstacle and it stays on the current cell.</p>
-
-<p>Design an algorithm to clean the entire room using only the 4 given APIs shown below.</p>
-
-<pre>
-interface Robot {
-&nbsp; // returns true if next cell is open and robot moves into the cell.
-&nbsp; // returns false if next cell is obstacle and robot stays on the current cell.
-&nbsp; boolean move();
-
-  // Robot will stay on the same cell after calling turnLeft/turnRight.
-&nbsp; // Each turn will be 90 degrees.
-&nbsp; void turnLeft();
-&nbsp; void turnRight();
-
-  // Clean the current cell.
-  void clean();
-}
-</pre>
-
-<p><strong>Example:</strong></p>
-
-<pre><strong>Input:</strong>
-room = [
-  [1,1,1,1,1,0,1,1],
-  [1,1,1,1,1,0,1,1],
-  [1,0,1,1,1,1,1,1],
-  [0,0,0,1,0,0,0,0],
-  [1,1,1,1,1,1,1,1]
-],
-row = 1,
-col = 3
-
-<strong>Explanation:</strong>
-All grids in the room are marked by either 0 or 1.
-0 means the cell is blocked, while 1 means the cell is accessible.
-The robot initially starts at the position of row=1, col=3.
-From the top left corner, its position is one row below and three columns right.
-</pre>
-
-<p><strong>Notes:</strong></p>
-
-<ol>
-	<li>The input is only given to initialize the room and the robot&#39;s position internally.&nbsp;You must solve this problem &quot;blindfolded&quot;. In other words, you must control the robot using only the mentioned 4 APIs, without knowing the room layout and the initial robot&#39;s position.</li>
-	<li>The robot&#39;s initial position will always be in an accessible cell.</li>
-	<li>The initial direction of the robot will be facing up.</li>
-	<li>All accessible cells are connected, which means the all cells marked as 1 will be accessible by the robot.</li>
-	<li>Assume all four edges of the grid are all surrounded by wall.</li>
-</ol>
-
-### Related Topics
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Similar Questions
-  1. [Walls and Gates](../walls-and-gates) (Medium)
-  1. [Shortest Path in a Hidden Grid](../shortest-path-in-a-hidden-grid) (Medium)
-  1. [Minimum Path Cost in a Hidden Grid](../minimum-path-cost-in-a-hidden-grid) (Medium)
diff --git a/problems/robot-room-cleaner/robot_room_cleaner.go b/problems/robot-room-cleaner/robot_room_cleaner.go
deleted file mode 100644
index c6b621c9d..000000000
--- a/problems/robot-room-cleaner/robot_room_cleaner.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem489
diff --git a/problems/robot-room-cleaner/robot_room_cleaner_test.go b/problems/robot-room-cleaner/robot_room_cleaner_test.go
deleted file mode 100644
index c6b621c9d..000000000
--- a/problems/robot-room-cleaner/robot_room_cleaner_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem489
diff --git a/problems/roman-to-integer/README.md b/problems/roman-to-integer/README.md
deleted file mode 100644
index 16486d247..000000000
--- a/problems/roman-to-integer/README.md
+++ /dev/null
@@ -1,97 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../integer-to-roman "Integer to Roman")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-common-prefix "Longest Common Prefix")
-
-## [13. Roman to Integer (Easy)](https://leetcode.com/problems/roman-to-integer "罗马数字转整数")
-
-<p>Roman numerals are represented by seven different symbols:&nbsp;<code>I</code>, <code>V</code>, <code>X</code>, <code>L</code>, <code>C</code>, <code>D</code> and <code>M</code>.</p>
-
-<pre>
-<strong>Symbol</strong>       <strong>Value</strong>
-I             1
-V             5
-X             10
-L             50
-C             100
-D             500
-M             1000</pre>
-
-<p>For example,&nbsp;<code>2</code> is written as <code>II</code>&nbsp;in Roman numeral, just two one&#39;s added together. <code>12</code> is written as&nbsp;<code>XII</code>, which is simply <code>X + II</code>. The number <code>27</code> is written as <code>XXVII</code>, which is <code>XX + V + II</code>.</p>
-
-<p>Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not <code>IIII</code>. Instead, the number four is written as <code>IV</code>. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as <code>IX</code>. There are six instances where subtraction is used:</p>
-
-<ul>
-	<li><code>I</code> can be placed before <code>V</code> (5) and <code>X</code> (10) to make 4 and 9.&nbsp;</li>
-	<li><code>X</code> can be placed before <code>L</code> (50) and <code>C</code> (100) to make 40 and 90.&nbsp;</li>
-	<li><code>C</code> can be placed before <code>D</code> (500) and <code>M</code> (1000) to make 400 and 900.</li>
-</ul>
-
-<p>Given a roman numeral, convert it to an integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;III&quot;
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;IV&quot;
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;IX&quot;
-<strong>Output:</strong> 9
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;LVIII&quot;
-<strong>Output:</strong> 58
-<strong>Explanation:</strong> L = 50, V= 5, III = 3.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;MCMXCIV&quot;
-<strong>Output:</strong> 1994
-<strong>Explanation:</strong> M = 1000, CM = 900, XC = 90 and IV = 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 15</code></li>
-	<li><code>s</code> contains only&nbsp;the characters <code>(&#39;I&#39;, &#39;V&#39;, &#39;X&#39;, &#39;L&#39;, &#39;C&#39;, &#39;D&#39;, &#39;M&#39;)</code>.</li>
-	<li>It is <strong>guaranteed</strong>&nbsp;that <code>s</code> is a valid roman numeral in the range <code>[1, 3999]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Integer to Roman](../integer-to-roman) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Problem is simpler to solve by working the string from back to front and using a map.
-</details>
diff --git a/problems/roman-to-integer/roman_to_integer.go b/problems/roman-to-integer/roman_to_integer.go
deleted file mode 100644
index a5b020f29..000000000
--- a/problems/roman-to-integer/roman_to_integer.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem13
-
-func romanToInt(s string) int {
-	m := map[byte]int{
-		'I': 1,
-		'V': 5,
-		'X': 10,
-		'L': 50,
-		'C': 100,
-		'D': 500,
-		'M': 1000,
-	}
-	ans, p := 0, 0
-	for i := 0; i < len(s); i++ {
-		k := s[i]
-		if v, ok := m[k]; ok {
-			if v > p {
-				ans -= p * 2
-			}
-			ans += v
-			p = v
-		}
-	}
-	return ans
-}
diff --git a/problems/roman-to-integer/roman_to_integer_test.go b/problems/roman-to-integer/roman_to_integer_test.go
deleted file mode 100644
index 5ccfa1daf..000000000
--- a/problems/roman-to-integer/roman_to_integer_test.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem13
-
-import "testing"
-
-func TestRomanToInt(t *testing.T) {
-	tests := map[string]int{
-		"III":     3,
-		"IV":      4,
-		"IX":      9,
-		"LVIII":   58,
-		"MCMXCIV": 1994,
-	}
-
-	for in, want := range tests {
-		got := romanToInt(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/rotate-array/README.md b/problems/rotate-array/README.md
deleted file mode 100644
index 9b80793b2..000000000
--- a/problems/rotate-array/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-time-to-buy-and-sell-stock-iv "Best Time to Buy and Sell Stock IV")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-bits "Reverse Bits")
-
-## [189. Rotate Array (Medium)](https://leetcode.com/problems/rotate-array "轮转数组")
-
-<p>Given an array, rotate the array to the right by <code>k</code> steps, where <code>k</code> is non-negative.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5,6,7], k = 3
-<strong>Output:</strong> [5,6,7,1,2,3,4]
-<strong>Explanation:</strong>
-rotate 1 steps to the right: [7,1,2,3,4,5,6]
-rotate 2 steps to the right: [6,7,1,2,3,4,5]
-rotate 3 steps to the right: [5,6,7,1,2,3,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,-100,3,99], k = 2
-<strong>Output:</strong> [3,99,-1,-100]
-<strong>Explanation:</strong> 
-rotate 1 steps to the right: [99,-1,-100,3]
-rotate 2 steps to the right: [3,99,-1,-100]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>0 &lt;= k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>Try to come up with as many solutions as you can. There are at least <strong>three</strong> different ways to solve this problem.</li>
-	<li>Could you do it in-place with <code>O(1)</code> extra space?</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Rotate List](../rotate-list) (Medium)
-  1. [Reverse Words in a String II](../reverse-words-in-a-string-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The easiest solution would use additional memory and that is perfectly fine.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The actual trick comes when trying to solve this problem without using any additional memory. This means you need to use the original array somehow to move the elements around. Now, we can place each element in its original location and shift all the elements around it to adjust as that would be too costly and most likely will time out on larger input arrays.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-One line of thought is based on reversing the array (or parts of it) to obtain the desired result. Think about how reversal might potentially help us out by using an example.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-The other line of thought is a tad bit complicated but essentially it builds on the idea of placing each element in its original position while keeping track of the element originally in that position. Basically, at every step, we place an element in its rightful position and keep track of the element already there or the one being overwritten in an additional variable. We can't do this in one linear pass and the idea here is based on <b>cyclic-dependencies</b> between elements.
-</details>
diff --git a/problems/rotate-array/rotate_array.go b/problems/rotate-array/rotate_array.go
deleted file mode 100644
index b468bdaba..000000000
--- a/problems/rotate-array/rotate_array.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem189
-
-func rotate(nums []int, k int) {
-	l := len(nums)
-	k %= l
-	s := make([]int, l)
-	copy(s, nums)
-	for i, v := range s[l-k:] {
-		nums[i] = v
-	}
-	for i, v := range s[:l-k] {
-		nums[k+i] = v
-	}
-}
diff --git a/problems/rotate-array/rotate_array_test.go b/problems/rotate-array/rotate_array_test.go
deleted file mode 100644
index 98283b6bc..000000000
--- a/problems/rotate-array/rotate_array_test.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package problem189
-
-import (
-	"reflect"
-	"testing"
-)
-
-type castType struct {
-	nums []int
-	k    int
-	want []int
-}
-
-func TestRotate(t *testing.T) {
-	tests := [...]castType{
-		{
-			nums: []int{1, 2, 3, 4, 5, 6, 7},
-			k:    3,
-			want: []int{5, 6, 7, 1, 2, 3, 4},
-		},
-		{
-			nums: []int{-1, -100, 3, 99},
-			k:    2,
-			want: []int{3, 99, -1, -100},
-		},
-		{
-			nums: []int{-1},
-			k:    2,
-			want: []int{-1},
-		},
-	}
-
-	for _, tt := range tests {
-		got := make([]int, len(tt.nums))
-		copy(got, tt.nums)
-		rotate(got, tt.k)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.nums, tt.k, got, tt.want)
-		}
-	}
-}
diff --git a/problems/rotate-function/README.md b/problems/rotate-function/README.md
deleted file mode 100644
index 1dd719a63..000000000
--- a/problems/rotate-function/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-substring-with-at-least-k-repeating-characters "Longest Substring with At Least K Repeating Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../integer-replacement "Integer Replacement")
-
-## [396. Rotate Function (Medium)](https://leetcode.com/problems/rotate-function "旋转函数")
-
-<p>You are given an integer array <code>nums</code> of length <code>n</code>.</p>
-
-<p>Assume <code>arr<sub>k</sub></code> to be an array obtained by rotating <code>nums</code> by <code>k</code> positions clock-wise. We define the <strong>rotation function</strong> <code>F</code> on <code>nums</code> as follow:</p>
-
-<ul>
-	<li><code>F(k) = 0 * arr<sub>k</sub>[0] + 1 * arr<sub>k</sub>[1] + ... + (n - 1) * arr<sub>k</sub>[n - 1].</code></li>
-</ul>
-
-<p>Return <em>the maximum value of</em> <code>F(0), F(1), ..., F(n-1)</code>.</p>
-
-<p>The test cases are generated so that the answer fits in a <strong>32-bit</strong> integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,3,2,6]
-<strong>Output:</strong> 26
-<strong>Explanation:</strong>
-F(0) = (0 * 4) + (1 * 3) + (2 * 2) + (3 * 6) = 0 + 3 + 4 + 18 = 25
-F(1) = (0 * 6) + (1 * 4) + (2 * 3) + (3 * 2) = 0 + 4 + 6 + 6 = 16
-F(2) = (0 * 2) + (1 * 6) + (2 * 4) + (3 * 3) = 0 + 6 + 8 + 9 = 23
-F(3) = (0 * 3) + (1 * 2) + (2 * 6) + (3 * 4) = 0 + 2 + 12 + 12 = 26
-So the maximum value of F(0), F(1), F(2), F(3) is F(3) = 26.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [100]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/rotate-function/rotate_function.go b/problems/rotate-function/rotate_function.go
deleted file mode 100644
index 2224c1d19..000000000
--- a/problems/rotate-function/rotate_function.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem396
diff --git a/problems/rotate-function/rotate_function_test.go b/problems/rotate-function/rotate_function_test.go
deleted file mode 100644
index 2224c1d19..000000000
--- a/problems/rotate-function/rotate_function_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem396
diff --git a/problems/rotate-image/README.md b/problems/rotate-image/README.md
deleted file mode 100644
index ad68bc8fe..000000000
--- a/problems/rotate-image/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../permutations-ii "Permutations II")
-　　　　　　　　　　　　　　　　
-[Next >](../group-anagrams "Group Anagrams")
-
-## [48. Rotate Image (Medium)](https://leetcode.com/problems/rotate-image "旋转图像")
-
-<p>You are given an <code>n x n</code> 2D <code>matrix</code> representing an image, rotate the image by <strong>90</strong> degrees (clockwise).</p>
-
-<p>You have to rotate the image <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank"><strong>in-place</strong></a>, which means you have to modify the input 2D matrix directly. <strong>DO NOT</strong> allocate another 2D matrix and do the rotation.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/28/mat1.jpg" style="width: 642px; height: 242px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,2,3],[4,5,6],[7,8,9]]
-<strong>Output:</strong> [[7,4,1],[8,5,2],[9,6,3]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/28/mat2.jpg" style="width: 800px; height: 321px;" />
-<pre>
-<strong>Input:</strong> matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
-<strong>Output:</strong> [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[1]]
-<strong>Output:</strong> [[1]]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[1,2],[3,4]]
-<strong>Output:</strong> [[3,1],[4,2]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>matrix.length == n</code></li>
-	<li><code>matrix[i].length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-	<li><code>-1000 &lt;= matrix[i][j] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/rotate-image/rotate_image.go b/problems/rotate-image/rotate_image.go
deleted file mode 100644
index 9536e5204..000000000
--- a/problems/rotate-image/rotate_image.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem48
-
-func rotate(matrix [][]int) {
-	l := len(matrix)
-	t := make([][]int, l)
-	for i := 0; i < l; i++ {
-		t[i] = make([]int, l)
-		copy(t[i], matrix[i])
-	}
-	for i := 0; i < l; i++ {
-		for j := 0; j < l; j++ {
-			matrix[j][l-1-i] = t[i][j]
-		}
-	}
-}
diff --git a/problems/rotate-image/rotate_image_test.go b/problems/rotate-image/rotate_image_test.go
deleted file mode 100644
index e79d4c3b6..000000000
--- a/problems/rotate-image/rotate_image_test.go
+++ /dev/null
@@ -1,55 +0,0 @@
-package problem48
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   [][]int
-	want [][]int
-}
-
-func TestRotate(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{1, 2, 3},
-				{4, 5, 6},
-				{7, 8, 9},
-			},
-			want: [][]int{
-				{7, 4, 1},
-				{8, 5, 2},
-				{9, 6, 3},
-			},
-		},
-		{
-			in: [][]int{
-				{5, 1, 9, 11},
-				{2, 4, 8, 10},
-				{13, 3, 6, 7},
-				{15, 14, 12, 16},
-			},
-			want: [][]int{
-				{15, 13, 2, 5},
-				{14, 3, 4, 1},
-				{12, 6, 8, 9},
-				{16, 7, 10, 11},
-			},
-		},
-	}
-
-	for _, tt := range tests {
-		l := len(tt.in)
-		got := make([][]int, l)
-		for i := 0; i < l; i++ {
-			got[i] = make([]int, l)
-			copy(got[i], tt.in[i])
-		}
-		rotate(got)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/rotate-list/README.md b/problems/rotate-list/README.md
deleted file mode 100644
index 02544a322..000000000
--- a/problems/rotate-list/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../permutation-sequence "Permutation Sequence")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-paths "Unique Paths")
-
-## [61. Rotate List (Medium)](https://leetcode.com/problems/rotate-list "旋转链表")
-
-<p>Given the <code>head</code> of a linked&nbsp;list, rotate the list to the right by <code>k</code> places.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/rotate1.jpg" style="width: 450px; height: 191px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5], k = 2
-<strong>Output:</strong> [4,5,1,2,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/roate2.jpg" style="width: 305px; height: 350px;" />
-<pre>
-<strong>Input:</strong> head = [0,1,2], k = 4
-<strong>Output:</strong> [2,0,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[0, 500]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-	<li><code>0 &lt;= k &lt;= 2 * 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Rotate Array](../rotate-array) (Medium)
-  1. [Split Linked List in Parts](../split-linked-list-in-parts) (Medium)
diff --git a/problems/rotate-list/rotate_list.go b/problems/rotate-list/rotate_list.go
deleted file mode 100644
index 32bd50fed..000000000
--- a/problems/rotate-list/rotate_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem61
diff --git a/problems/rotate-list/rotate_list_test.go b/problems/rotate-list/rotate_list_test.go
deleted file mode 100644
index 32bd50fed..000000000
--- a/problems/rotate-list/rotate_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem61
diff --git a/problems/rotate-string/README.md b/problems/rotate-string/README.md
deleted file mode 100644
index 239d3dced..000000000
--- a/problems/rotate-string/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-subarrays-with-bounded-maximum "Number of Subarrays with Bounded Maximum")
-　　　　　　　　　　　　　　　　
-[Next >](../all-paths-from-source-to-target "All Paths From Source to Target")
-
-## [796. Rotate String (Easy)](https://leetcode.com/problems/rotate-string "旋转字符串")
-
-<p>Given two strings <code>s</code> and <code>goal</code>, return <code>true</code> <em>if and only if</em> <code>s</code> <em>can become</em> <code>goal</code> <em>after some number of <strong>shifts</strong> on</em> <code>s</code>.</p>
-
-<p>A <strong>shift</strong> on <code>s</code> consists of moving the leftmost character of <code>s</code> to the rightmost position.</p>
-
-<ul>
-	<li>For example, if <code>s = &quot;abcde&quot;</code>, then it will be <code>&quot;bcdea&quot;</code> after one shift.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "abcde", goal = "cdeab"
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "abcde", goal = "abced"
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, goal.length &lt;= 100</code></li>
-	<li><code>s</code> and <code>goal</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
diff --git a/problems/rotate-string/rotate_string.go b/problems/rotate-string/rotate_string.go
deleted file mode 100644
index 1206446a4..000000000
--- a/problems/rotate-string/rotate_string.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package problem796
-
-import "strings"
-
-func rotateString(A string, B string) bool {
-	if len(A) != len(B) {
-		return false
-	}
-	A = strings.Repeat(A, 2)
-	return strings.Contains(A, B)
-}
diff --git a/problems/rotate-string/rotate_string_test.go b/problems/rotate-string/rotate_string_test.go
deleted file mode 100644
index ded3a7430..000000000
--- a/problems/rotate-string/rotate_string_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem796
-
-import "testing"
-
-type testType struct {
-	A    string
-	B    string
-	want bool
-}
-
-func TestRotateString(t *testing.T) {
-	tests := [...]testType{
-		{
-			A:    "abcde",
-			B:    "cdeab",
-			want: true,
-		},
-		{
-			A:    "abcde",
-			B:    "abced",
-			want: false,
-		},
-		{
-			A:    "abcde",
-			B:    "abcdef",
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := rotateString(tt.A, tt.B)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.A, tt.B, got, tt.want)
-		}
-	}
-}
diff --git a/problems/rotated-digits/README.md b/problems/rotated-digits/README.md
deleted file mode 100644
index c4eb7c509..000000000
--- a/problems/rotated-digits/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cheapest-flights-within-k-stops "Cheapest Flights Within K Stops")
-　　　　　　　　　　　　　　　　
-[Next >](../escape-the-ghosts "Escape The Ghosts")
-
-## [788. Rotated Digits (Medium)](https://leetcode.com/problems/rotated-digits "旋转数字")
-
-<p>An integer <code>x</code> is a <strong>good</strong> if after rotating each digit individually by 180 degrees, we get a valid number that is different from <code>x</code>. Each digit must be rotated - we cannot choose to leave it alone.</p>
-
-<p>A number is valid if each digit remains a digit after rotation. For example:</p>
-
-<ul>
-	<li><code>0</code>, <code>1</code>, and <code>8</code> rotate to themselves,</li>
-	<li><code>2</code> and <code>5</code> rotate to each other (in this case they are rotated in a different direction, in other words, <code>2</code> or <code>5</code> gets mirrored),</li>
-	<li><code>6</code> and <code>9</code> rotate to each other, and</li>
-	<li>the rest of the numbers do not rotate to any other number and become invalid.</li>
-</ul>
-
-<p>Given an integer <code>n</code>, return <em>the number of <strong>good</strong> integers in the range </em><code>[1, n]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are four good numbers in the range [1, 10] : 2, 5, 6, 9.
-Note that 1 and 10 are not good numbers, since they remain unchanged after rotating.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/rotated-digits/rotated_digits.go b/problems/rotated-digits/rotated_digits.go
deleted file mode 100644
index 8a0ffe2c3..000000000
--- a/problems/rotated-digits/rotated_digits.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem788
-
-func rotatedDigits(N int) int {
-	count := 0
-	for i := 2; i <= N; i++ {
-		x, ok := i, 0
-		for x != 0 {
-			switch x % 10 {
-			case 2, 5, 6, 9:
-				ok = 1
-			case 3, 4, 7:
-				ok, x = 0, 0
-			}
-			x /= 10
-		}
-		count += ok
-	}
-	return count
-}
diff --git a/problems/rotated-digits/rotated_digits_test.go b/problems/rotated-digits/rotated_digits_test.go
deleted file mode 100644
index e338a914d..000000000
--- a/problems/rotated-digits/rotated_digits_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem788
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestRotatedDigits(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   10,
-			want: 4,
-		},
-		{
-			in:   23,
-			want: 11,
-		},
-		{
-			in:   100,
-			want: 40,
-		},
-		{
-			in:   200,
-			want: 81,
-		},
-	}
-	for _, tt := range tests {
-		got := rotatedDigits(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/rotating-the-box/README.md b/problems/rotating-the-box/README.md
deleted file mode 100644
index c7b5a2d59..000000000
--- a/problems/rotating-the-box/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../incremental-memory-leak "Incremental Memory Leak")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-floored-pairs "Sum of Floored Pairs")
-
-## [1861. Rotating the Box (Medium)](https://leetcode.com/problems/rotating-the-box "旋转盒子")
-
-<p>You are given an <code>m x n</code> matrix of characters <code>box</code> representing a side-view of a box. Each cell of the box is one of the following:</p>
-
-<ul>
-	<li>A stone <code>&#39;#&#39;</code></li>
-	<li>A stationary obstacle <code>&#39;*&#39;</code></li>
-	<li>Empty <code>&#39;.&#39;</code></li>
-</ul>
-
-<p>The box is rotated <strong>90 degrees clockwise</strong>, causing some of the stones to fall due to gravity. Each stone falls down until it lands on an obstacle, another stone, or the bottom of the box. Gravity <strong>does not</strong> affect the obstacles&#39; positions, and the inertia from the box&#39;s rotation <strong>does not </strong>affect the stones&#39; horizontal positions.</p>
-
-<p>It is <strong>guaranteed</strong> that each stone in <code>box</code> rests on an obstacle, another stone, or the bottom of the box.</p>
-
-<p>Return <em>an </em><code>n x m</code><em> matrix representing the box after the rotation described above</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/rotatingtheboxleetcodewithstones.png" style="width: 300px; height: 150px;" /></p>
-
-<pre>
-<strong>Input:</strong> box = [[&quot;#&quot;,&quot;.&quot;,&quot;#&quot;]]
-<strong>Output:</strong> [[&quot;.&quot;],
-&nbsp;        [&quot;#&quot;],
-&nbsp;        [&quot;#&quot;]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/rotatingtheboxleetcode2withstones.png" style="width: 375px; height: 195px;" /></p>
-
-<pre>
-<strong>Input:</strong> box = [[&quot;#&quot;,&quot;.&quot;,&quot;*&quot;,&quot;.&quot;],
-&nbsp;             [&quot;#&quot;,&quot;#&quot;,&quot;*&quot;,&quot;.&quot;]]
-<strong>Output:</strong> [[&quot;#&quot;,&quot;.&quot;],
-&nbsp;        [&quot;#&quot;,&quot;#&quot;],
-&nbsp;        [&quot;*&quot;,&quot;*&quot;],
-&nbsp;        [&quot;.&quot;,&quot;.&quot;]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/rotatingtheboxleetcode3withstone.png" style="width: 400px; height: 218px;" /></p>
-
-<pre>
-<strong>Input:</strong> box = [[&quot;#&quot;,&quot;#&quot;,&quot;*&quot;,&quot;.&quot;,&quot;*&quot;,&quot;.&quot;],
-&nbsp;             [&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;*&quot;,&quot;.&quot;,&quot;.&quot;],
-&nbsp;             [&quot;#&quot;,&quot;#&quot;,&quot;#&quot;,&quot;.&quot;,&quot;#&quot;,&quot;.&quot;]]
-<strong>Output:</strong> [[&quot;.&quot;,&quot;#&quot;,&quot;#&quot;],
-&nbsp;        [&quot;.&quot;,&quot;#&quot;,&quot;#&quot;],
-&nbsp;        [&quot;#&quot;,&quot;#&quot;,&quot;*&quot;],
-&nbsp;        [&quot;#&quot;,&quot;*&quot;,&quot;.&quot;],
-&nbsp;        [&quot;#&quot;,&quot;.&quot;,&quot;*&quot;],
-&nbsp;        [&quot;#&quot;,&quot;.&quot;,&quot;.&quot;]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == box.length</code></li>
-	<li><code>n == box[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 500</code></li>
-	<li><code>box[i][j]</code> is either <code>&#39;#&#39;</code>, <code>&#39;*&#39;</code>, or <code>&#39;.&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Rotate the box using the relation rotatedBox[i][j] = box[m - 1 - j][i].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Start iterating from the bottom of the box and for each empty cell check if there is any stone above it with no obstacles between them.
-</details>
diff --git a/problems/rotting-oranges/README.md b/problems/rotting-oranges/README.md
deleted file mode 100644
index d1b38db31..000000000
--- a/problems/rotting-oranges/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cousins-in-binary-tree "Cousins in Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-k-consecutive-bit-flips "Minimum Number of K Consecutive Bit Flips")
-
-## [994. Rotting Oranges (Medium)](https://leetcode.com/problems/rotting-oranges "腐烂的橘子")
-
-<p>You are given an <code>m x n</code> <code>grid</code> where each cell can have one of three values:</p>
-
-<ul>
-	<li><code>0</code> representing an empty cell,</li>
-	<li><code>1</code> representing a fresh orange, or</li>
-	<li><code>2</code> representing a rotten orange.</li>
-</ul>
-
-<p>Every minute, any fresh orange that is <strong>4-directionally adjacent</strong> to a rotten orange becomes rotten.</p>
-
-<p>Return <em>the minimum number of minutes that must elapse until no cell has a fresh orange</em>. If <em>this is impossible, return</em> <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/16/oranges.png" style="width: 650px; height: 137px;" />
-<pre>
-<strong>Input:</strong> grid = [[2,1,1],[1,1,0],[0,1,1]]
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[2,1,1],[0,1,1],[1,0,1]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> The orange in the bottom left corner (row 2, column 0) is never rotten, because rotting only happens 4-directionally.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0,2]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Since there are already no fresh oranges at minute 0, the answer is just 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 10</code></li>
-	<li><code>grid[i][j]</code> is <code>0</code>, <code>1</code>, or <code>2</code>.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Walls and Gates](../walls-and-gates) (Medium)
diff --git a/problems/rotting-oranges/rotting_oranges.go b/problems/rotting-oranges/rotting_oranges.go
deleted file mode 100644
index c534aa233..000000000
--- a/problems/rotting-oranges/rotting_oranges.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem994
-
-func orangesRotting(grid [][]int) int {
-	r, c, minutes := len(grid), len(grid[0]), 0
-	freshCount, rottens := 0, make([]int, 0)
-	for i := 0; i < r; i++ {
-		for j := 0; j < c; j++ {
-			if grid[i][j] == 1 {
-				freshCount++
-			} else if grid[i][j] == 2 {
-				rottens = append(rottens, i*c+j)
-			}
-		}
-	}
-	for l := len(rottens); l > 0 && freshCount > 0; l = len(rottens) {
-		for _, p := range rottens {
-			for k := 0; k < 4; k++ {
-				i, j := p/c+k-2, p%c+k-1
-				if k == 0 {
-					i += 2
-				} else if k == 3 {
-					j -= 2
-				}
-				if 0 <= i && i < r && 0 <= j && j < c && grid[i][j] == 1 {
-					grid[i][j], freshCount, rottens = 2, freshCount-1, append(rottens, i*c+j)
-				}
-			}
-		}
-		minutes, rottens = minutes+1, rottens[l:]
-	}
-	if freshCount > 0 {
-		return -1
-	}
-	return minutes
-}
diff --git a/problems/rotting-oranges/rotting_oranges_test.go b/problems/rotting-oranges/rotting_oranges_test.go
deleted file mode 100644
index 9ba440447..000000000
--- a/problems/rotting-oranges/rotting_oranges_test.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package problem994
-
-import "testing"
-
-type testType struct {
-	in   [][]int
-	want int
-}
-
-func TestOrangesRotting(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{2, 1, 1},
-				{1, 1, 0},
-				{0, 1, 1},
-			},
-			want: 4,
-		},
-		{
-			in: [][]int{
-				{2, 1, 1},
-				{0, 1, 1},
-				{1, 0, 1},
-			},
-			want: -1,
-		},
-		{
-			in: [][]int{
-				{0, 2},
-			},
-			want: 0,
-		},
-		{
-			in: [][]int{
-				{1, 2},
-			},
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := orangesRotting(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/running-sum-of-1d-array/README.md b/problems/running-sum-of-1d-array/README.md
deleted file mode 100644
index 00ceb6f78..000000000
--- a/problems/running-sum-of-1d-array/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sales-by-day-of-the-week "Sales by Day of the Week")
-　　　　　　　　　　　　　　　　
-[Next >](../least-number-of-unique-integers-after-k-removals "Least Number of Unique Integers after K Removals")
-
-## [1480. Running Sum of 1d Array (Easy)](https://leetcode.com/problems/running-sum-of-1d-array "一维数组的动态和")
-
-<p>Given an array <code>nums</code>. We define a running sum of an array as&nbsp;<code>runningSum[i] = sum(nums[0]&hellip;nums[i])</code>.</p>
-
-<p>Return the running sum of <code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> [1,3,6,10]
-<strong>Explanation:</strong> Running sum is obtained as follows: [1, 1+2, 1+2+3, 1+2+3+4].</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,1,1]
-<strong>Output:</strong> [1,2,3,4,5]
-<strong>Explanation:</strong> Running sum is obtained as follows: [1, 1+1, 1+1+1, 1+1+1+1, 1+1+1+1+1].</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,2,10,1]
-<strong>Output:</strong> [3,4,6,16,17]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>-10^6&nbsp;&lt;= nums[i] &lt;=&nbsp;10^6</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think about how we can calculate the i-th number in the running sum from the (i-1)-th number.
-</details>
diff --git a/problems/running-total-for-different-genders/README.md b/problems/running-total-for-different-genders/README.md
deleted file mode 100644
index 107500405..000000000
--- a/problems/running-total-for-different-genders/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../verbal-arithmetic-puzzle "Verbal Arithmetic Puzzle")
-　　　　　　　　　　　　　　　　
-[Next >](../decrypt-string-from-alphabet-to-integer-mapping "Decrypt String from Alphabet to Integer Mapping")
-
-## [1308. Running Total for Different Genders (Medium)](https://leetcode.com/problems/running-total-for-different-genders "不同性别每日分数总计")
-
-<p>Table: <code>Scores</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| player_name   | varchar |
-| gender        | varchar |
-| day           | date    |
-| score_points  | int     |
-+---------------+---------+
-(gender, day) is the primary key for this table.
-A competition is held between females team and males team.
-Each row of this table indicates that a player_name and with gender has scored score_point in someday.
-Gender is 'F' if the player is in females team and 'M' if the player is in males team.
- </pre>
-
-Write an SQL query to find the total score for each gender at each day.
-
-Order the result table by gender and day
-
-The query result format is in the following example:
-<pre>
-Scores table:
-+-------------+--------+------------+--------------+
-| player_name | gender | day        | score_points |
-+-------------+--------+------------+--------------+
-| Aron        | F      | 2020-01-01 | 17           |
-| Alice       | F      | 2020-01-07 | 23           |
-| Bajrang     | M      | 2020-01-07 | 7            |
-| Khali       | M      | 2019-12-25 | 11           |
-| Slaman      | M      | 2019-12-30 | 13           |
-| Joe         | M      | 2019-12-31 | 3            |
-| Jose        | M      | 2019-12-18 | 2            |
-| Priya       | F      | 2019-12-31 | 23           |
-| Priyanka    | F      | 2019-12-30 | 17           |
-+-------------+--------+------------+--------------+
-Result table:
-+--------+------------+-------+
-| gender | day        | total |
-+--------+------------+-------+
-| F      | 2019-12-30 | 17    |
-| F      | 2019-12-31 | 40    |
-| F      | 2020-01-01 | 57    |
-| F      | 2020-01-07 | 80    |
-| M      | 2019-12-18 | 2     |
-| M      | 2019-12-25 | 13    |
-| M      | 2019-12-30 | 26    |
-| M      | 2019-12-31 | 29    |
-| M      | 2020-01-07 | 36    |
-+--------+------------+-------+
-For females team:
-First day is 2019-12-30, Priyanka scored 17 points and the total score for the team is 17.
-Second day is 2019-12-31, Priya scored 23 points and the total score for the team is 40.
-Third day is 2020-01-01, Aron scored 17 points and the total score for the team is 57.
-Fourth day is 2020-01-07, Alice scored 23 points and the total score for the team is 80.
-For males team:
-First day is 2019-12-18, Jose scored 2 points and the total score for the team is 2.
-Second day is 2019-12-25, Khali scored 11 points and the total score for the team is 13.
-Third day is 2019-12-30, Slaman scored 13 points and the total score for the team is 26.
-Fourth day is 2019-12-31, Joe scored 3 points and the total score for the team is 29.
-Fifth day is 2020-01-07, Bajrang scored 7 points and the total score for the team is 36.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/running-total-for-different-genders/mysql_schemas.sql b/problems/running-total-for-different-genders/mysql_schemas.sql
deleted file mode 100644
index 365fc0407..000000000
--- a/problems/running-total-for-different-genders/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Scores (player_name varchar(20), gender varchar(1), day date, score_points int);
-Truncate table Scores;
-insert into Scores (player_name, gender, day, score_points) values ('Aron', 'F', '2020-01-01', '17');
-insert into Scores (player_name, gender, day, score_points) values ('Alice', 'F', '2020-01-07', '23');
-insert into Scores (player_name, gender, day, score_points) values ('Bajrang', 'M', '2020-01-07', '7');
-insert into Scores (player_name, gender, day, score_points) values ('Khali', 'M', '2019-12-25', '11');
-insert into Scores (player_name, gender, day, score_points) values ('Slaman', 'M', '2019-12-30', '13');
-insert into Scores (player_name, gender, day, score_points) values ('Joe', 'M', '2019-12-31', '3');
-insert into Scores (player_name, gender, day, score_points) values ('Jose', 'M', '2019-12-18', '2');
-insert into Scores (player_name, gender, day, score_points) values ('Priya', 'F', '2019-12-31', '23');
-insert into Scores (player_name, gender, day, score_points) values ('Priyanka', 'F', '2019-12-30', '17');
diff --git a/problems/russian-doll-envelopes/README.md b/problems/russian-doll-envelopes/README.md
deleted file mode 100644
index 96062bae2..000000000
--- a/problems/russian-doll-envelopes/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-snake-game "Design Snake Game")
-　　　　　　　　　　　　　　　　
-[Next >](../design-twitter "Design Twitter")
-
-## [354. Russian Doll Envelopes (Hard)](https://leetcode.com/problems/russian-doll-envelopes "俄罗斯套娃信封问题")
-
-<p>You are given a 2D array of integers <code>envelopes</code> where <code>envelopes[i] = [w<sub>i</sub>, h<sub>i</sub>]</code> represents the width and the height of an envelope.</p>
-
-<p>One envelope can fit into another if and only if both the width and height of one envelope are greater than the other envelope&#39;s width and height.</p>
-
-<p>Return <em>the maximum number of envelopes you can Russian doll (i.e., put one inside the other)</em>.</p>
-
-<p><strong>Note:</strong> You cannot rotate an envelope.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> envelopes = [[5,4],[6,4],[6,7],[2,3]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The maximum number of envelopes you can Russian doll is <code>3</code> ([2,3] =&gt; [5,4] =&gt; [6,7]).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> envelopes = [[1,1],[1,1],[1,1]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= envelopes.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>envelopes[i].length == 2</code></li>
-	<li><code>1 &lt;= w<sub>i</sub>, h<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Longest Increasing Subsequence](../longest-increasing-subsequence) (Medium)
-  1. [The Number of Weak Characters in the Game](../the-number-of-weak-characters-in-the-game) (Medium)
diff --git a/problems/russian-doll-envelopes/russian_doll_envelopes.go b/problems/russian-doll-envelopes/russian_doll_envelopes.go
deleted file mode 100644
index c92ca1c73..000000000
--- a/problems/russian-doll-envelopes/russian_doll_envelopes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem354
diff --git a/problems/russian-doll-envelopes/russian_doll_envelopes_test.go b/problems/russian-doll-envelopes/russian_doll_envelopes_test.go
deleted file mode 100644
index c92ca1c73..000000000
--- a/problems/russian-doll-envelopes/russian_doll_envelopes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem354
diff --git a/problems/sales-analysis-i/README.md b/problems/sales-analysis-i/README.md
deleted file mode 100644
index 7f9b0f947..000000000
--- a/problems/sales-analysis-i/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-subsequence-of-distinct-characters "Smallest Subsequence of Distinct Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../sales-analysis-ii "Sales Analysis II")
-
-## [1082. Sales Analysis I (Easy)](https://leetcode.com/problems/sales-analysis-i "销售分析 I ")
-
-<p>Table:&nbsp;<code>Product</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| product_id   | int     |
-| product_name | varchar |
-| unit_price   | int     |
-+--------------+---------+
-product_id is the primary key of this table.
-</pre>
-
-<p>Table:&nbsp;<code>Sales</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| seller_id   | int     |
-| product_id  | int     |
-| buyer_id    | int     |
-| sale_date   | date    |
-| quantity    | int     |
-| price       | int     |
-+------ ------+---------+
-This table has no primary key, it can have repeated rows.
-product_id is a foreign key to Product table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the best&nbsp;<strong>seller</strong>&nbsp;by total sales price, If there is a tie, report them all.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Product table:
-+------------+--------------+------------+
-| product_id | product_name | unit_price |
-+------------+--------------+------------+
-| 1          | S8           | 1000       |
-| 2          | G4           | 800        |
-| 3          | iPhone       | 1400       |
-+------------+--------------+------------+
-
-<code>Sales </code>table:
-+-----------+------------+----------+------------+----------+-------+
-| seller_id | product_id | buyer_id | sale_date  | quantity | price |
-+-----------+------------+----------+------------+----------+-------+
-| 1         | 1          | 1        | 2019-01-21 | 2        | 2000  |
-| 1         | 2          | 2        | 2019-02-17 | 1        | 800   |
-| 2         | 2          | 3        | 2019-06-02 | 1        | 800   |
-| 3         | 3          | 4        | 2019-05-13 | 2        | 2800  |
-+-----------+------------+----------+------------+----------+-------+
-
-Result table:
-+-------------+
-| seller_id   |
-+-------------+
-| 1           |
-| 3           |
-+-------------+
-Both sellers with id 1 and 3 sold products with the most total price of 2800.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/sales-analysis-i/mysql_schemas.sql b/problems/sales-analysis-i/mysql_schemas.sql
deleted file mode 100644
index 501c5e913..000000000
--- a/problems/sales-analysis-i/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Product (product_id int, product_name varchar(10), unit_price int);
-Create table If Not Exists Sales (seller_id int, product_id int, buyer_id int, sale_date date, quantity int, price int);
-Truncate table Product;
-insert into Product (product_id, product_name, unit_price) values ('1', 'S8', '1000');
-insert into Product (product_id, product_name, unit_price) values ('2', 'G4', '800');
-insert into Product (product_id, product_name, unit_price) values ('3', 'iPhone', '1400');
-Truncate table Sales;
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('1', '1', '1', '2019-01-21', '2', '2000');
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('1', '2', '2', '2019-02-17', '1', '800');
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('2', '2', '3', '2019-06-02', '1', '800');
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('3', '3', '4', '2019-05-13', '2', '2800');
diff --git a/problems/sales-analysis-i/sales_analysis_i.sql b/problems/sales-analysis-i/sales_analysis_i.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/sales-analysis-i/sales_analysis_i.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/sales-analysis-ii/README.md b/problems/sales-analysis-ii/README.md
deleted file mode 100644
index c0995e4d1..000000000
--- a/problems/sales-analysis-ii/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sales-analysis-i "Sales Analysis I")
-　　　　　　　　　　　　　　　　
-[Next >](../sales-analysis-iii "Sales Analysis III")
-
-## [1083. Sales Analysis II (Easy)](https://leetcode.com/problems/sales-analysis-ii "销售分析 II")
-
-<p>Table:&nbsp;<code>Product</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| product_id   | int     |
-| product_name | varchar |
-| unit_price   | int     |
-+--------------+---------+
-product_id is the primary key of this table.
-</pre>
-
-<p>Table:&nbsp;<code>Sales</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| seller_id   | int     |
-| product_id  | int     |
-| buyer_id    | int     |
-| sale_date   | date    |
-| quantity    | int     |
-| price       | int     |
-+------ ------+---------+
-This table has no primary key, it can have repeated rows.
-product_id is a foreign key to Product table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the <strong>buyers</strong> who have bought <em>S8</em> but not <em>iPhone</em>. Note that <em>S8</em> and <em>iPhone</em> are products present in the <code>Product</code> table.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Product table:
-+------------+--------------+------------+
-| product_id | product_name | unit_price |
-+------------+--------------+------------+
-| 1          | S8           | 1000       |
-| 2          | G4           | 800        |
-| 3          | iPhone       | 1400       |
-+------------+--------------+------------+
-
-<code>Sales </code>table:
-+-----------+------------+----------+------------+----------+-------+
-| seller_id | product_id | buyer_id | sale_date  | quantity | price |
-+-----------+------------+----------+------------+----------+-------+
-| 1         | 1          | 1        | 2019-01-21 | 2        | 2000  |
-| 1         | 2          | 2        | 2019-02-17 | 1        | 800   |
-| 2         | 1          | 3        | 2019-06-02 | 1        | 800   |
-| 3         | 3          | 3        | 2019-05-13 | 2        | 2800  |
-+-----------+------------+----------+------------+----------+-------+
-
-Result table:
-+-------------+
-| buyer_id    |
-+-------------+
-| 1           |
-+-------------+
-The buyer with id 1 bought an S8 but didn&#39;t buy an iPhone. The buyer with id 3 bought both.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Sales Analysis I](../sales-analysis-i) (Easy)
-  1. [Sales Analysis III](../sales-analysis-iii) (Easy)
diff --git a/problems/sales-analysis-ii/mysql_schemas.sql b/problems/sales-analysis-ii/mysql_schemas.sql
deleted file mode 100644
index 18cbd6647..000000000
--- a/problems/sales-analysis-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Product (product_id int, product_name varchar(10), unit_price int);
-Create table If Not Exists Sales (seller_id int, product_id int, buyer_id int, sale_date date, quantity int, price int);
-Truncate table Product;
-insert into Product (product_id, product_name, unit_price) values ('1', 'S8', '1000');
-insert into Product (product_id, product_name, unit_price) values ('2', 'G4', '800');
-insert into Product (product_id, product_name, unit_price) values ('3', 'iPhone', '1400');
-Truncate table Sales;
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('1', '1', '1', '2019-01-21', '2', '2000');
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('1', '2', '2', '2019-02-17', '1', '800');
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('2', '1', '3', '2019-06-02', '1', '800');
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('3', '3', '3', '2019-05-13', '2', '2800');
diff --git a/problems/sales-analysis-ii/sales_analysis_ii.sql b/problems/sales-analysis-ii/sales_analysis_ii.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/sales-analysis-ii/sales_analysis_ii.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/sales-analysis-iii/README.md b/problems/sales-analysis-iii/README.md
deleted file mode 100644
index 82d94eef2..000000000
--- a/problems/sales-analysis-iii/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sales-analysis-ii "Sales Analysis II")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-digits-in-the-minimum-number "Sum of Digits in the Minimum Number")
-
-## [1084. Sales Analysis III (Easy)](https://leetcode.com/problems/sales-analysis-iii "销售分析III")
-
-<p>Table:&nbsp;<code>Product</code></p>
-
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| product_id   | int     |
-| product_name | varchar |
-| unit_price   | int     |
-+--------------+---------+
-product_id is the primary key of this table.
-</pre>
-
-<p>Table:&nbsp;<code>Sales</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| seller_id   | int     |
-| product_id  | int     |
-| buyer_id    | int     |
-| sale_date   | date    |
-| quantity    | int     |
-| price       | int     |
-+------ ------+---------+
-This table has no primary key, it can have repeated rows.
-product_id is a foreign key to Product table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the <strong>products</strong>&nbsp;that were <strong>only</strong>&nbsp;sold in spring 2019. That is, between&nbsp;<strong>2019-01-01</strong> and <strong>2019-03-31</strong> inclusive.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Product table:
-+------------+--------------+------------+
-| product_id | product_name | unit_price |
-+------------+--------------+------------+
-| 1          | S8           | 1000       |
-| 2          | G4           | 800        |
-| 3          | iPhone       | 1400       |
-+------------+--------------+------------+
-
-<code>Sales </code>table:
-+-----------+------------+----------+------------+----------+-------+
-| seller_id | product_id | buyer_id | sale_date  | quantity | price |
-+-----------+------------+----------+------------+----------+-------+
-| 1         | 1          | 1        | 2019-01-21 | 2        | 2000  |
-| 1         | 2          | 2        | 2019-02-17 | 1        | 800   |
-| 2         | 2          | 3        | 2019-06-02 | 1        | 800   |
-| 3         | 3          | 4        | 2019-05-13 | 2        | 2800  |
-+-----------+------------+----------+------------+----------+-------+
-
-Result table:
-+-------------+--------------+
-| product_id  | product_name |
-+-------------+--------------+
-| 1           | S8           |
-+-------------+--------------+
-The product with id 1 was only sold in spring 2019 while the other two were sold after.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/sales-analysis-iii/mysql_schemas.sql b/problems/sales-analysis-iii/mysql_schemas.sql
deleted file mode 100644
index 501c5e913..000000000
--- a/problems/sales-analysis-iii/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Product (product_id int, product_name varchar(10), unit_price int);
-Create table If Not Exists Sales (seller_id int, product_id int, buyer_id int, sale_date date, quantity int, price int);
-Truncate table Product;
-insert into Product (product_id, product_name, unit_price) values ('1', 'S8', '1000');
-insert into Product (product_id, product_name, unit_price) values ('2', 'G4', '800');
-insert into Product (product_id, product_name, unit_price) values ('3', 'iPhone', '1400');
-Truncate table Sales;
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('1', '1', '1', '2019-01-21', '2', '2000');
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('1', '2', '2', '2019-02-17', '1', '800');
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('2', '2', '3', '2019-06-02', '1', '800');
-insert into Sales (seller_id, product_id, buyer_id, sale_date, quantity, price) values ('3', '3', '4', '2019-05-13', '2', '2800');
diff --git a/problems/sales-analysis-iii/sales_analysis_iii.sql b/problems/sales-analysis-iii/sales_analysis_iii.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/sales-analysis-iii/sales_analysis_iii.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/sales-by-day-of-the-week/README.md b/problems/sales-by-day-of-the-week/README.md
deleted file mode 100644
index 753d7a48d..000000000
--- a/problems/sales-by-day-of-the-week/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../allocate-mailboxes "Allocate Mailboxes")
-　　　　　　　　　　　　　　　　
-[Next >](../running-sum-of-1d-array "Running Sum of 1d Array")
-
-## [1479. Sales by Day of the Week (Hard)](https://leetcode.com/problems/sales-by-day-of-the-week "周内每天的销售情况")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/sales-by-day-of-the-week/mysql_schemas.sql b/problems/sales-by-day-of-the-week/mysql_schemas.sql
deleted file mode 100644
index 24328670f..000000000
--- a/problems/sales-by-day-of-the-week/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create table If Not Exists Orders (order_id int, customer_id int, order_date date, item_id varchar(30), quantity int);
-Create table If Not Exists Items (item_id varchar(30), item_name varchar(30), item_category varchar(30));
-Truncate table Orders;
-insert into Orders (order_id, customer_id, order_date, item_id, quantity) values ('1', '1', '2020-06-01', '1', '10');
-insert into Orders (order_id, customer_id, order_date, item_id, quantity) values ('2', '1', '2020-06-08', '2', '10');
-insert into Orders (order_id, customer_id, order_date, item_id, quantity) values ('3', '2', '2020-06-02', '1', '5');
-insert into Orders (order_id, customer_id, order_date, item_id, quantity) values ('4', '3', '2020-06-03', '3', '5');
-insert into Orders (order_id, customer_id, order_date, item_id, quantity) values ('5', '4', '2020-06-04', '4', '1');
-insert into Orders (order_id, customer_id, order_date, item_id, quantity) values ('6', '4', '2020-06-05', '5', '5');
-insert into Orders (order_id, customer_id, order_date, item_id, quantity) values ('7', '5', '2020-06-05', '1', '10');
-insert into Orders (order_id, customer_id, order_date, item_id, quantity) values ('8', '5', '2020-06-14', '4', '5');
-insert into Orders (order_id, customer_id, order_date, item_id, quantity) values ('9', '5', '2020-06-21', '3', '5');
-Truncate table Items;
-insert into Items (item_id, item_name, item_category) values ('1', 'LC Alg. Book', 'Book');
-insert into Items (item_id, item_name, item_category) values ('2', 'LC DB. Book', 'Book');
-insert into Items (item_id, item_name, item_category) values ('3', 'LC SmarthPhone', 'Phone');
-insert into Items (item_id, item_name, item_category) values ('4', 'LC Phone 2020', 'Phone');
-insert into Items (item_id, item_name, item_category) values ('5', 'LC SmartGlass', 'Glasses');
-insert into Items (item_id, item_name, item_category) values ('6', 'LC T-Shirt XL', 'T-shirt');
diff --git a/problems/sales-person/README.md b/problems/sales-person/README.md
deleted file mode 100644
index 1c51029ea..000000000
--- a/problems/sales-person/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-string-from-binary-tree "Construct String from Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../tree-node "Tree Node")
-
-## [607. Sales Person (Easy)](https://leetcode.com/problems/sales-person "销售员")
-
-<p><b>Description</b></p>
-
-<p>Given three tables: <code>salesperson</code>, <code>company</code>, <code>orders</code>.<br />
-Output all the <b>names</b> in the table <code>salesperson</code>, who didn&rsquo;t have sales to company &#39;RED&#39;.</p>
-
-<p><b>Example</b><br />
-<b>Input</b></p>
-
-<p>Table: <code>salesperson</code></p>
-
-<pre>
-+----------+------+--------+-----------------+-----------+
-| sales_id | name | salary | commission_rate | hire_date |
-+----------+------+--------+-----------------+-----------+
-|   1      | John | 100000 |     6           | 4/1/2006  |
-|   2      | Amy  | 120000 |     5           | 5/1/2010  |
-|   3      | Mark | 65000  |     12          | 12/25/2008|
-|   4      | Pam  | 25000  |     25          | 1/1/2005  |
-|   5      | Alex | 50000  |     10          | 2/3/2007  |
-+----------+------+--------+-----------------+-----------+
-</pre>
-The table <code>salesperson</code> holds the salesperson information. Every salesperson has a <b>sales_id</b> and a <b>name</b>.
-
-<p>Table: <code>company</code></p>
-
-<pre>
-+---------+--------+------------+
-| com_id  |  name  |    city    |
-+---------+--------+------------+
-|   1     |  RED   |   Boston   |
-|   2     | ORANGE |   New York |
-|   3     | YELLOW |   Boston   |
-|   4     | GREEN  |   Austin   |
-+---------+--------+------------+
-</pre>
-The table <code>company</code> holds the company information. Every company has a <b>com_id</b> and a <b>name</b>.
-
-<p>Table: <code>orders</code></p>
-
-<pre>
-+----------+------------+---------+----------+--------+
-| order_id | order_date | com_id  | sales_id | amount |
-+----------+------------+---------+----------+--------+
-| 1        |   1/1/2014 |    3    |    4     | 100000 |
-| 2        |   2/1/2014 |    4    |    5     | 5000   |
-| 3        |   3/1/2014 |    1    |    1     | 50000  |
-| 4        |   4/1/2014 |    1    |    4     | 25000  |
-+----------+----------+---------+----------+--------+
-</pre>
-The table <code>orders</code> holds the sales record information, salesperson and customer company are represented by <b>sales_id</b> and <b>com_id</b>.
-
-<p><b>output</b></p>
-
-<pre>
-+------+
-| name | 
-+------+
-| Amy  | 
-| Mark | 
-| Alex |
-+------+
-</pre>
-
-<p><b>Explanation</b></p>
-
-<p>According to order &#39;3&#39; and &#39;4&#39; in table <code>orders</code>, it is easy to tell only salesperson &#39;John&#39; and &#39;Alex&#39; have sales to company &#39;RED&#39;,<br />
-so we need to output all the other <b>names</b> in table <code>salesperson</code>.</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You need to query who sold to company 'RED' first, then output the sales person who is not in the first query result.
-</details>
diff --git a/problems/sales-person/mysql_schemas.sql b/problems/sales-person/mysql_schemas.sql
deleted file mode 100644
index b583e9691..000000000
--- a/problems/sales-person/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create table If Not Exists SalesPerson (sales_id int, name varchar(255), salary int, commission_rate int, hire_date date);
-Create table If Not Exists Company (com_id int, name varchar(255), city varchar(255));
-Create table If Not Exists Orders (order_id int, order_date date, com_id int, sales_id int, amount int);
-Truncate table SalesPerson;
-insert into SalesPerson (sales_id, name, salary, commission_rate, hire_date) values ('1', 'John', '100000', '6', '4/1/2006');
-insert into SalesPerson (sales_id, name, salary, commission_rate, hire_date) values ('2', 'Amy', '12000', '5', '5/1/2010');
-insert into SalesPerson (sales_id, name, salary, commission_rate, hire_date) values ('3', 'Mark', '65000', '12', '12/25/2008');
-insert into SalesPerson (sales_id, name, salary, commission_rate, hire_date) values ('4', 'Pam', '25000', '25', '1/1/2005');
-insert into SalesPerson (sales_id, name, salary, commission_rate, hire_date) values ('5', 'Alex', '5000', '10', '2/3/2007');
-Truncate table Company;
-insert into Company (com_id, name, city) values ('1', 'RED', 'Boston');
-insert into Company (com_id, name, city) values ('2', 'ORANGE', 'New York');
-insert into Company (com_id, name, city) values ('3', 'YELLOW', 'Boston');
-insert into Company (com_id, name, city) values ('4', 'GREEN', 'Austin');
-Truncate table Orders;
-insert into Orders (order_id, order_date, com_id, sales_id, amount) values ('1', '1/1/2014', '3', '4', '10000');
-insert into Orders (order_id, order_date, com_id, sales_id, amount) values ('2', '2/1/2014', '4', '5', '5000');
-insert into Orders (order_id, order_date, com_id, sales_id, amount) values ('3', '3/1/2014', '1', '1', '50000');
-insert into Orders (order_id, order_date, com_id, sales_id, amount) values ('4', '4/1/2014', '1', '4', '25000');
diff --git a/problems/sales-person/sales_person.sql b/problems/sales-person/sales_person.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/sales-person/sales_person.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/same-tree/README.md b/problems/same-tree/README.md
deleted file mode 100644
index 9f6006314..000000000
--- a/problems/same-tree/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../recover-binary-search-tree "Recover Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../symmetric-tree "Symmetric Tree")
-
-## [100. Same Tree (Easy)](https://leetcode.com/problems/same-tree "相同的树")
-
-<p>Given the roots of two binary trees <code>p</code> and <code>q</code>, write a function to check if they are the same or not.</p>
-
-<p>Two binary trees are considered the same if they are structurally identical, and the nodes have the same value.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/20/ex1.jpg" style="width: 622px; height: 182px;" />
-<pre>
-<strong>Input:</strong> p = [1,2,3], q = [1,2,3]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/20/ex2.jpg" style="width: 382px; height: 182px;" />
-<pre>
-<strong>Input:</strong> p = [1,2], q = [1,null,2]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/20/ex3.jpg" style="width: 622px; height: 182px;" />
-<pre>
-<strong>Input:</strong> p = [1,2,1], q = [1,1,2]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in both trees is in the range <code>[0, 100]</code>.</li>
-	<li><code>-10<sup>4</sup> &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/same-tree/same_tree.go b/problems/same-tree/same_tree.go
deleted file mode 100644
index d5af0401b..000000000
--- a/problems/same-tree/same_tree.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem100
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func isSameTree(p *TreeNode, q *TreeNode) bool {
-	if p == nil {
-		return q == nil
-	} else if q == nil || p.Val != q.Val {
-		return false
-	}
-	return isSameTree(p.Left, q.Left) && isSameTree(p.Right, q.Right)
-}
diff --git a/problems/same-tree/same_tree_test.go b/problems/same-tree/same_tree_test.go
deleted file mode 100644
index 76493b9d1..000000000
--- a/problems/same-tree/same_tree_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem100
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	p    []int
-	q    []int
-	want bool
-}
-
-func TestIsSameTree(t *testing.T) {
-	tests := [...]testType{
-		{
-			p:    []int{1, 2, 3},
-			q:    []int{1, 2, 3},
-			want: true,
-		},
-		{
-			p:    []int{1, 2},
-			q:    []int{1, kit.NULL, 2},
-			want: false,
-		},
-		{
-			p:    []int{1, 2, 1},
-			q:    []int{1, 1, 2},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isSameTree(kit.SliceInt2TreeNode(tt.p), kit.SliceInt2TreeNode(tt.q))
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.p, tt.q, got, tt.want)
-		}
-	}
-}
diff --git a/problems/satisfiability-of-equality-equations/README.md b/problems/satisfiability-of-equality-equations/README.md
deleted file mode 100644
index a5c93aed6..000000000
--- a/problems/satisfiability-of-equality-equations/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-to-array-form-of-integer "Add to Array-Form of Integer")
-　　　　　　　　　　　　　　　　
-[Next >](../broken-calculator "Broken Calculator")
-
-## [990. Satisfiability of Equality Equations (Medium)](https://leetcode.com/problems/satisfiability-of-equality-equations "等式方程的可满足性")
-
-<p>You are given an array of strings <code>equations</code> that represent relationships between variables where each string <code>equations[i]</code> is of length <code>4</code> and takes one of two different forms: <code>&quot;x<sub>i</sub>==y<sub>i</sub>&quot;</code> or <code>&quot;x<sub>i</sub>!=y<sub>i</sub>&quot;</code>.Here, <code>x<sub>i</sub></code> and <code>y<sub>i</sub></code> are lowercase letters (not necessarily different) that represent one-letter variable names.</p>
-
-<p>Return <code>true</code><em> if it is possible to assign integers to variable names so as to satisfy all the given equations, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> equations = [&quot;a==b&quot;,&quot;b!=a&quot;]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> If we assign say, a = 1 and b = 1, then the first equation is satisfied, but not the second.
-There is no way to assign the variables to satisfy both equations.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> equations = [&quot;b==a&quot;,&quot;a==b&quot;]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We could assign a = 1 and b = 1 to satisfy both equations.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> equations = [&quot;a==b&quot;,&quot;b==c&quot;,&quot;a==c&quot;]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> equations = [&quot;a==b&quot;,&quot;b!=c&quot;,&quot;c==a&quot;]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> equations = [&quot;c==c&quot;,&quot;b==d&quot;,&quot;x!=z&quot;]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= equations.length &lt;= 500</code></li>
-	<li><code>equations[i].length == 4</code></li>
-	<li><code>equations[i][0]</code> is a lowercase letter.</li>
-	<li><code>equations[i][1]</code> is either <code>&#39;=&#39;</code> or <code>&#39;!&#39;</code>.</li>
-	<li><code>equations[i][2]</code> is <code>&#39;=&#39;</code>.</li>
-	<li><code>equations[i][3]</code> is a lowercase letter.</li>
-</ul>
-
-### Related Topics
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/satisfiability-of-equality-equations/satisfiability_of_equality_equations.go b/problems/satisfiability-of-equality-equations/satisfiability_of_equality_equations.go
deleted file mode 100644
index 56ed9ad0f..000000000
--- a/problems/satisfiability-of-equality-equations/satisfiability_of_equality_equations.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem990
diff --git a/problems/score-after-flipping-matrix/README.md b/problems/score-after-flipping-matrix/README.md
deleted file mode 100644
index 4fdce91e4..000000000
--- a/problems/score-after-flipping-matrix/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../lemonade-change "Lemonade Change")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-subarray-with-sum-at-least-k "Shortest Subarray with Sum at Least K")
-
-## [861. Score After Flipping Matrix (Medium)](https://leetcode.com/problems/score-after-flipping-matrix "翻转矩阵后的得分")
-
-<p>You are given an <code>m x n</code> binary matrix <code>grid</code>.</p>
-
-<p>A <strong>move</strong> consists of choosing any row or column and toggling each value in that row or column (i.e., changing all <code>0</code>&#39;s to <code>1</code>&#39;s, and all <code>1</code>&#39;s to <code>0</code>&#39;s).</p>
-
-<p>Every row of the matrix is interpreted as a binary number, and the <strong>score</strong> of the matrix is the sum of these numbers.</p>
-
-<p>Return <em>the highest possible <strong>score</strong> after making any number of <strong>moves</strong> (including zero moves)</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-toogle1.jpg" style="width: 500px; height: 299px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,0,1,1],[1,0,1,0],[1,1,0,0]]
-<strong>Output:</strong> 39
-<strong>Explanation:</strong> 0b1111 + 0b1001 + 0b1111 = 15 + 9 + 15 = 39
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 20</code></li>
-	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/score-after-flipping-matrix/score_after_flipping_matrix.go b/problems/score-after-flipping-matrix/score_after_flipping_matrix.go
deleted file mode 100644
index af95f0df8..000000000
--- a/problems/score-after-flipping-matrix/score_after_flipping_matrix.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem861
diff --git a/problems/score-after-flipping-matrix/score_after_flipping_matrix_test.go b/problems/score-after-flipping-matrix/score_after_flipping_matrix_test.go
deleted file mode 100644
index af95f0df8..000000000
--- a/problems/score-after-flipping-matrix/score_after_flipping_matrix_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem861
diff --git a/problems/score-of-parentheses/README.md b/problems/score-of-parentheses/README.md
deleted file mode 100644
index f03ada8ca..000000000
--- a/problems/score-of-parentheses/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../exam-room "Exam Room")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-hire-k-workers "Minimum Cost to Hire K Workers")
-
-## [856. Score of Parentheses (Medium)](https://leetcode.com/problems/score-of-parentheses "括号的分数")
-
-<p>Given a balanced parentheses string <code>s</code>, return <em>the <strong>score</strong> of the string</em>.</p>
-
-<p>The <strong>score</strong> of a balanced parentheses string is based on the following rule:</p>
-
-<ul>
-	<li><code>&quot;()&quot;</code> has score <code>1</code>.</li>
-	<li><code>AB</code> has score <code>A + B</code>, where <code>A</code> and <code>B</code> are balanced parentheses strings.</li>
-	<li><code>(A)</code> has score <code>2 * A</code>, where <code>A</code> is a balanced parentheses string.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "()"
-<strong>Output:</strong> 1
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "(())"
-<strong>Output:</strong> 2
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s = "()()"
-<strong>Output:</strong> 2
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> s = "(()(()))"
-<strong>Output:</strong> 6
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 50</code></li>
-	<li><code>s</code> consists of only <code>&#39;(&#39;</code> and <code>&#39;)&#39;</code>.</li>
-	<li><code>s</code> is a balanced parentheses string.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/score-of-parentheses/score_of_parentheses.go b/problems/score-of-parentheses/score_of_parentheses.go
deleted file mode 100644
index f8b6dfbf1..000000000
--- a/problems/score-of-parentheses/score_of_parentheses.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem856
diff --git a/problems/score-of-parentheses/score_of_parentheses_test.go b/problems/score-of-parentheses/score_of_parentheses_test.go
deleted file mode 100644
index f8b6dfbf1..000000000
--- a/problems/score-of-parentheses/score_of_parentheses_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem856
diff --git a/problems/scramble-string/README.md b/problems/scramble-string/README.md
deleted file mode 100644
index 3dfafc5ac..000000000
--- a/problems/scramble-string/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partition-list "Partition List")
-　　　　　　　　　　　　　　　　
-[Next >](../merge-sorted-array "Merge Sorted Array")
-
-## [87. Scramble String (Hard)](https://leetcode.com/problems/scramble-string "扰乱字符串")
-
-<p>We can scramble a string s to get a string t using the following algorithm:</p>
-
-<ol>
-	<li>If the length of the string is 1, stop.</li>
-	<li>If the length of the string is &gt; 1, do the following:
-	<ul>
-		<li>Split the string into two non-empty substrings at a random index, i.e., if the string is <code>s</code>, divide it to <code>x</code> and <code>y</code> where <code>s = x + y</code>.</li>
-		<li><strong>Randomly</strong>&nbsp;decide to swap the two substrings or to keep them in the same order. i.e., after this step, <code>s</code> may become <code>s = x + y</code> or <code>s = y + x</code>.</li>
-		<li>Apply step 1 recursively on each of the two substrings <code>x</code> and <code>y</code>.</li>
-	</ul>
-	</li>
-</ol>
-
-<p>Given two strings <code>s1</code> and <code>s2</code> of <strong>the same length</strong>, return <code>true</code> if <code>s2</code> is a scrambled string of <code>s1</code>, otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;great&quot;, s2 = &quot;rgeat&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> One possible scenario applied on s1 is:
-&quot;great&quot; --&gt; &quot;gr/eat&quot; // divide at random index.
-&quot;gr/eat&quot; --&gt; &quot;gr/eat&quot; // random decision is not to swap the two substrings and keep them in order.
-&quot;gr/eat&quot; --&gt; &quot;g/r / e/at&quot; // apply the same algorithm recursively on both substrings. divide at ranom index each of them.
-&quot;g/r / e/at&quot; --&gt; &quot;r/g / e/at&quot; // random decision was to swap the first substring and to keep the second substring in the same order.
-&quot;r/g / e/at&quot; --&gt; &quot;r/g / e/ a/t&quot; // again apply the algorithm recursively, divide &quot;at&quot; to &quot;a/t&quot;.
-&quot;r/g / e/ a/t&quot; --&gt; &quot;r/g / e/ a/t&quot; // random decision is to keep both substrings in the same order.
-The algorithm stops now and the result string is &quot;rgeat&quot; which is s2.
-As there is one possible scenario that led s1 to be scrambled to s2, we return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;abcde&quot;, s2 = &quot;caebd&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s1 = &quot;a&quot;, s2 = &quot;a&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>s1.length == s2.length</code></li>
-	<li><code>1 &lt;= s1.length &lt;= 30</code></li>
-	<li><code>s1</code> and <code>s2</code> consist of lower-case English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/scramble-string/scramble_string.go b/problems/scramble-string/scramble_string.go
deleted file mode 100644
index 3cb29585e..000000000
--- a/problems/scramble-string/scramble_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem87
diff --git a/problems/scramble-string/scramble_string_test.go b/problems/scramble-string/scramble_string_test.go
deleted file mode 100644
index 3cb29585e..000000000
--- a/problems/scramble-string/scramble_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem87
diff --git a/problems/search-a-2d-matrix-ii/README.md b/problems/search-a-2d-matrix-ii/README.md
deleted file mode 100644
index ef44b3d7d..000000000
--- a/problems/search-a-2d-matrix-ii/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sliding-window-maximum "Sliding Window Maximum")
-　　　　　　　　　　　　　　　　
-[Next >](../different-ways-to-add-parentheses "Different Ways to Add Parentheses")
-
-## [240. Search a 2D Matrix II (Medium)](https://leetcode.com/problems/search-a-2d-matrix-ii "搜索二维矩阵 II")
-
-<p>Write an efficient algorithm that searches for a <code>target</code> value in an <code>m x n</code> integer <code>matrix</code>. The <code>matrix</code> has the following properties:</p>
-
-<ul>
-	<li>Integers in each row are sorted in ascending from left to right.</li>
-	<li>Integers in each column are sorted in ascending from top to bottom.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/24/searchgrid2.jpg" style="width: 300px; height: 300px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 5
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/24/searchgrid.jpg" style="width: 300px; height: 300px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 20
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= n, m &lt;= 300</code></li>
-	<li><code>-10<sup>9</sup> &lt;= matrix[i][j] &lt;= 10<sup>9</sup></code></li>
-	<li>All the integers in each row are <strong>sorted</strong> in ascending order.</li>
-	<li>All the integers in each column are <strong>sorted</strong> in ascending order.</li>
-	<li><code>-10<sup>9</sup> &lt;= target &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Search a 2D Matrix](../search-a-2d-matrix) (Medium)
diff --git a/problems/search-a-2d-matrix-ii/search_a_2d_matrix_ii.go b/problems/search-a-2d-matrix-ii/search_a_2d_matrix_ii.go
deleted file mode 100644
index eecf0983f..000000000
--- a/problems/search-a-2d-matrix-ii/search_a_2d_matrix_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem240
diff --git a/problems/search-a-2d-matrix-ii/search_a_2d_matrix_ii_test.go b/problems/search-a-2d-matrix-ii/search_a_2d_matrix_ii_test.go
deleted file mode 100644
index eecf0983f..000000000
--- a/problems/search-a-2d-matrix-ii/search_a_2d_matrix_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem240
diff --git a/problems/search-a-2d-matrix/README.md b/problems/search-a-2d-matrix/README.md
deleted file mode 100644
index 35e2e654e..000000000
--- a/problems/search-a-2d-matrix/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../set-matrix-zeroes "Set Matrix Zeroes")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-colors "Sort Colors")
-
-## [74. Search a 2D Matrix (Medium)](https://leetcode.com/problems/search-a-2d-matrix "搜索二维矩阵")
-
-<p>Write an efficient algorithm that searches for a value in an <code>m x n</code> matrix. This matrix has the following properties:</p>
-
-<ul>
-	<li>Integers in each row are sorted from left to right.</li>
-	<li>The first integer of each row is greater than the last integer of the previous row.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/05/mat.jpg" style="width: 322px; height: 242px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/05/mat2.jpg" style="width: 322px; height: 242px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li><code>-10<sup>4</sup> &lt;= matrix[i][j], target &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Search a 2D Matrix II](../search-a-2d-matrix-ii) (Medium)
diff --git a/problems/search-a-2d-matrix/search_a_2d_matrix.go b/problems/search-a-2d-matrix/search_a_2d_matrix.go
deleted file mode 100644
index a2c0f2c92..000000000
--- a/problems/search-a-2d-matrix/search_a_2d_matrix.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem74
diff --git a/problems/search-a-2d-matrix/search_a_2d_matrix_test.go b/problems/search-a-2d-matrix/search_a_2d_matrix_test.go
deleted file mode 100644
index a2c0f2c92..000000000
--- a/problems/search-a-2d-matrix/search_a_2d_matrix_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem74
diff --git a/problems/search-in-a-binary-search-tree/README.md b/problems/search-in-a-binary-search-tree/README.md
deleted file mode 100644
index 68060b3b2..000000000
--- a/problems/search-in-a-binary-search-tree/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../falling-squares "Falling Squares")
-　　　　　　　　　　　　　　　　
-[Next >](../insert-into-a-binary-search-tree "Insert into a Binary Search Tree")
-
-## [700. Search in a Binary Search Tree (Easy)](https://leetcode.com/problems/search-in-a-binary-search-tree "二叉搜索树中的搜索")
-
-<p>You are given the <code>root</code> of a binary search tree (BST) and an integer <code>val</code>.</p>
-
-<p>Find the node in the BST that the node&#39;s value equals <code>val</code> and return the subtree rooted with that node. If such a node does not exist, return <code>null</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/12/tree1.jpg" style="width: 422px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [4,2,7,1,3], val = 2
-<strong>Output:</strong> [2,1,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/12/tree2.jpg" style="width: 422px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [4,2,7,1,3], val = 5
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 5000]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 10<sup>7</sup></code></li>
-	<li><code>root</code> is a binary search tree.</li>
-	<li><code>1 &lt;= val &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Closest Binary Search Tree Value](../closest-binary-search-tree-value) (Easy)
-  1. [Insert into a Binary Search Tree](../insert-into-a-binary-search-tree) (Medium)
diff --git a/problems/search-in-a-binary-search-tree/search_in_a_binary_search_tree.go b/problems/search-in-a-binary-search-tree/search_in_a_binary_search_tree.go
deleted file mode 100644
index feb9c531c..000000000
--- a/problems/search-in-a-binary-search-tree/search_in_a_binary_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem700
diff --git a/problems/search-in-a-binary-search-tree/search_in_a_binary_search_tree_test.go b/problems/search-in-a-binary-search-tree/search_in_a_binary_search_tree_test.go
deleted file mode 100644
index feb9c531c..000000000
--- a/problems/search-in-a-binary-search-tree/search_in_a_binary_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem700
diff --git a/problems/search-in-a-sorted-array-of-unknown-size/README.md b/problems/search-in-a-sorted-array-of-unknown-size/README.md
deleted file mode 100644
index 871493340..000000000
--- a/problems/search-in-a-sorted-array-of-unknown-size/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../insert-into-a-binary-search-tree "Insert into a Binary Search Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-largest-element-in-a-stream "Kth Largest Element in a Stream")
-
-## [702. Search in a Sorted Array of Unknown Size (Medium)](https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size "搜索长度未知的有序数组")
-
-<p>Given an&nbsp;integer array sorted in ascending order, write a function to search <code>target</code> in <code>nums</code>.&nbsp; If <code>target</code> exists, then return its index, otherwise return <code>-1</code>. <strong>However, the array size is unknown to you</strong>. You may only access the array using an <code>ArrayReader</code>&nbsp;interface, where&nbsp;<code>ArrayReader.get(k)</code> returns the element of the array at index <code>k</code>&nbsp;(0-indexed).</p>
-
-<p>You may assume all integers in the array are less than&nbsp;<code>10000</code>, and if you access the array out of bounds, <code>ArrayReader.get</code> will return <code>2147483647</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre><strong>Input:</strong> <code>array</code> = [-1,0,3,5,9,12], <code>target</code> = 9
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> 9 exists in <code>nums</code> and its index is 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre><strong>Input:</strong> <code>array</code> = [-1,0,3,5,9,12], <code>target</code> = 2
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> 2 does not exist in <code>nums</code> so return -1</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>You may assume that all elements in the array are unique.</li>
-	<li>The value of each element in the array&nbsp;will be in the range <code>[-9999, 9999]</code>.</li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Similar Questions
-  1. [Binary Search](../binary-search) (Easy)
diff --git a/problems/search-in-a-sorted-array-of-unknown-size/search_in_a_sorted_array_of_unknown_size.go b/problems/search-in-a-sorted-array-of-unknown-size/search_in_a_sorted_array_of_unknown_size.go
deleted file mode 100644
index 24689696e..000000000
--- a/problems/search-in-a-sorted-array-of-unknown-size/search_in_a_sorted_array_of_unknown_size.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem702
diff --git a/problems/search-in-a-sorted-array-of-unknown-size/search_in_a_sorted_array_of_unknown_size_test.go b/problems/search-in-a-sorted-array-of-unknown-size/search_in_a_sorted_array_of_unknown_size_test.go
deleted file mode 100644
index 24689696e..000000000
--- a/problems/search-in-a-sorted-array-of-unknown-size/search_in_a_sorted_array_of_unknown_size_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem702
diff --git a/problems/search-in-rotated-sorted-array-ii/README.md b/problems/search-in-rotated-sorted-array-ii/README.md
deleted file mode 100644
index 8bf333932..000000000
--- a/problems/search-in-rotated-sorted-array-ii/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-duplicates-from-sorted-array-ii "Remove Duplicates from Sorted Array II")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-duplicates-from-sorted-list-ii "Remove Duplicates from Sorted List II")
-
-## [81. Search in Rotated Sorted Array II (Medium)](https://leetcode.com/problems/search-in-rotated-sorted-array-ii "搜索旋转排序数组 II")
-
-<p>There is an integer array <code>nums</code> sorted in non-decreasing order (not necessarily with <strong>distinct</strong> values).</p>
-
-<p>Before being passed to your function, <code>nums</code> is <strong>rotated</strong> at an unknown pivot index <code>k</code> (<code>0 &lt;= k &lt; nums.length</code>) such that the resulting array is <code>[nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]]</code> (<strong>0-indexed</strong>). For example, <code>[0,1,2,4,4,4,5,6,6,7]</code> might be rotated at pivot index <code>5</code> and become <code>[4,5,6,6,7,0,1,2,4,4]</code>.</p>
-
-<p>Given the array <code>nums</code> <strong>after</strong> the rotation and an integer <code>target</code>, return <code>true</code><em> if </em><code>target</code><em> is in </em><code>nums</code><em>, or </em><code>false</code><em> if it is not in </em><code>nums</code><em>.</em></p>
-
-<p>You must decrease the overall operation steps as much as possible.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [2,5,6,0,0,1,2], target = 0
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [2,5,6,0,0,1,2], target = 3
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5000</code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>nums</code> is guaranteed to be rotated at some pivot.</li>
-	<li><code>-10<sup>4</sup> &lt;= target &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> This problem is similar to&nbsp;<a href="/problems/search-in-rotated-sorted-array/description/" target="_blank">Search in Rotated Sorted Array</a>, but&nbsp;<code>nums</code> may contain <strong>duplicates</strong>. Would this affect the runtime complexity? How and why?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Search in Rotated Sorted Array](../search-in-rotated-sorted-array) (Medium)
diff --git a/problems/search-in-rotated-sorted-array-ii/search_in_rotated_sorted_array_ii.go b/problems/search-in-rotated-sorted-array-ii/search_in_rotated_sorted_array_ii.go
deleted file mode 100644
index f2c28c443..000000000
--- a/problems/search-in-rotated-sorted-array-ii/search_in_rotated_sorted_array_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem81
diff --git a/problems/search-in-rotated-sorted-array-ii/search_in_rotated_sorted_array_ii_test.go b/problems/search-in-rotated-sorted-array-ii/search_in_rotated_sorted_array_ii_test.go
deleted file mode 100644
index f2c28c443..000000000
--- a/problems/search-in-rotated-sorted-array-ii/search_in_rotated_sorted_array_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem81
diff --git a/problems/search-in-rotated-sorted-array/README.md b/problems/search-in-rotated-sorted-array/README.md
deleted file mode 100644
index 1fe16bcb6..000000000
--- a/problems/search-in-rotated-sorted-array/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-valid-parentheses "Longest Valid Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../find-first-and-last-position-of-element-in-sorted-array "Find First and Last Position of Element in Sorted Array")
-
-## [33. Search in Rotated Sorted Array (Medium)](https://leetcode.com/problems/search-in-rotated-sorted-array "搜索旋转排序数组")
-
-<p>There is an integer array <code>nums</code> sorted in ascending order (with <strong>distinct</strong> values).</p>
-
-<p>Prior to being passed to your function, <code>nums</code> is <strong>rotated</strong> at an unknown pivot index <code>k</code> (<code>0 &lt;= k &lt; nums.length</code>) such that the resulting array is <code>[nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]]</code> (<strong>0-indexed</strong>). For example, <code>[0,1,2,4,5,6,7]</code> might be rotated at pivot index <code>3</code> and become <code>[4,5,6,7,0,1,2]</code>.</p>
-
-<p>Given the array <code>nums</code> <strong>after</strong> the rotation and an integer <code>target</code>, return <em>the index of </em><code>target</code><em> if it is in </em><code>nums</code><em>, or </em><code>-1</code><em> if it is not in </em><code>nums</code>.</p>
-
-<p>You must&nbsp;write an algorithm with&nbsp;<code>O(log n)</code> runtime complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [4,5,6,7,0,1,2], target = 0
-<strong>Output:</strong> 4
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [4,5,6,7,0,1,2], target = 3
-<strong>Output:</strong> -1
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [1], target = 0
-<strong>Output:</strong> -1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5000</code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li>All values of <code>nums</code> are <strong>unique</strong>.</li>
-	<li><code>nums</code> is guaranteed to be rotated at some pivot.</li>
-	<li><code>-10<sup>4</sup> &lt;= target &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Search in Rotated Sorted Array II](../search-in-rotated-sorted-array-ii) (Medium)
-  1. [Find Minimum in Rotated Sorted Array](../find-minimum-in-rotated-sorted-array) (Medium)
diff --git a/problems/search-in-rotated-sorted-array/search_in_rotated_sorted_array.go b/problems/search-in-rotated-sorted-array/search_in_rotated_sorted_array.go
deleted file mode 100644
index d6a1bba56..000000000
--- a/problems/search-in-rotated-sorted-array/search_in_rotated_sorted_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem33
diff --git a/problems/search-in-rotated-sorted-array/search_in_rotated_sorted_array_test.go b/problems/search-in-rotated-sorted-array/search_in_rotated_sorted_array_test.go
deleted file mode 100644
index d6a1bba56..000000000
--- a/problems/search-in-rotated-sorted-array/search_in_rotated_sorted_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem33
diff --git a/problems/search-insert-position/README.md b/problems/search-insert-position/README.md
deleted file mode 100644
index 09a83df93..000000000
--- a/problems/search-insert-position/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-first-and-last-position-of-element-in-sorted-array "Find First and Last Position of Element in Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-sudoku "Valid Sudoku")
-
-## [35. Search Insert Position (Easy)](https://leetcode.com/problems/search-insert-position "搜索插入位置")
-
-<p>Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.</p>
-
-<p>You must&nbsp;write an algorithm with&nbsp;<code>O(log n)</code> runtime complexity.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,5,6], target = 5
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,5,6], target = 2
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,5,6], target = 7
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>nums</code> contains <strong>distinct</strong> values sorted in <strong>ascending</strong> order.</li>
-	<li><code>-10<sup>4</sup> &lt;= target &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [First Bad Version](../first-bad-version) (Easy)
diff --git a/problems/search-insert-position/search_insert_position.go b/problems/search-insert-position/search_insert_position.go
deleted file mode 100644
index 2ddc7fb52..000000000
--- a/problems/search-insert-position/search_insert_position.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem35
-
-func searchInsert(nums []int, target int) int {
-	for i, v := range nums {
-		if target <= v {
-			return i
-		}
-	}
-	return len(nums)
-}
diff --git a/problems/search-insert-position/search_insert_position_test.go b/problems/search-insert-position/search_insert_position_test.go
deleted file mode 100644
index 2f8387a91..000000000
--- a/problems/search-insert-position/search_insert_position_test.go
+++ /dev/null
@@ -1,46 +0,0 @@
-package problem35
-
-import "testing"
-
-type testType struct {
-	nums   []int
-	target int
-	want   int
-}
-
-func TestSearchInsert(t *testing.T) {
-	tests := [...]testType{
-		{
-			nums:   []int{2, 7, 11, 15},
-			target: 5,
-			want:   1,
-		},
-		{
-			nums:   []int{1, 3, 5, 6},
-			target: 2,
-			want:   1,
-		},
-		{
-			nums:   []int{1, 3, 5, 6},
-			target: 7,
-			want:   4,
-		},
-		{
-			nums:   []int{1, 3, 5, 6},
-			target: 7,
-			want:   4,
-		},
-		{
-			nums:   []int{1, 3, 5, 6},
-			target: 0,
-			want:   0,
-		},
-	}
-
-	for _, tt := range tests {
-		got := searchInsert(tt.nums, tt.target)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.nums, got, tt.want)
-		}
-	}
-}
diff --git a/problems/search-suggestions-system/README.md b/problems/search-suggestions-system/README.md
deleted file mode 100644
index be6fd4f4d..000000000
--- a/problems/search-suggestions-system/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-servers-that-communicate "Count Servers that Communicate")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-ways-to-stay-in-the-same-place-after-some-steps "Number of Ways to Stay in the Same Place After Some Steps")
-
-## [1268. Search Suggestions System (Medium)](https://leetcode.com/problems/search-suggestions-system "搜索推荐系统")
-
-<p>You are given an array of strings <code>products</code> and a string <code>searchWord</code>.</p>
-
-<p>Design a system that suggests at most three product names from <code>products</code> after each character of <code>searchWord</code> is typed. Suggested products should have common prefix with <code>searchWord</code>. If there are more than three products with a common prefix return the three lexicographically minimums products.</p>
-
-<p>Return <em>a list of lists of the suggested products after each character of </em><code>searchWord</code><em> is typed</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> products = [&quot;mobile&quot;,&quot;mouse&quot;,&quot;moneypot&quot;,&quot;monitor&quot;,&quot;mousepad&quot;], searchWord = &quot;mouse&quot;
-<strong>Output:</strong> [
-[&quot;mobile&quot;,&quot;moneypot&quot;,&quot;monitor&quot;],
-[&quot;mobile&quot;,&quot;moneypot&quot;,&quot;monitor&quot;],
-[&quot;mouse&quot;,&quot;mousepad&quot;],
-[&quot;mouse&quot;,&quot;mousepad&quot;],
-[&quot;mouse&quot;,&quot;mousepad&quot;]
-]
-<strong>Explanation:</strong> products sorted lexicographically = [&quot;mobile&quot;,&quot;moneypot&quot;,&quot;monitor&quot;,&quot;mouse&quot;,&quot;mousepad&quot;]
-After typing m and mo all products match and we show user [&quot;mobile&quot;,&quot;moneypot&quot;,&quot;monitor&quot;]
-After typing mou, mous and mouse the system suggests [&quot;mouse&quot;,&quot;mousepad&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> products = [&quot;havana&quot;], searchWord = &quot;havana&quot;
-<strong>Output:</strong> [[&quot;havana&quot;],[&quot;havana&quot;],[&quot;havana&quot;],[&quot;havana&quot;],[&quot;havana&quot;],[&quot;havana&quot;]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> products = [&quot;bags&quot;,&quot;baggage&quot;,&quot;banner&quot;,&quot;box&quot;,&quot;cloths&quot;], searchWord = &quot;bags&quot;
-<strong>Output:</strong> [[&quot;baggage&quot;,&quot;bags&quot;,&quot;banner&quot;],[&quot;baggage&quot;,&quot;bags&quot;,&quot;banner&quot;],[&quot;baggage&quot;,&quot;bags&quot;],[&quot;bags&quot;]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= products.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= products[i].length &lt;= 3000</code></li>
-	<li><code>1 &lt;= sum(products[i].length) &lt;= 2 * 10<sup>4</sup></code></li>
-	<li>All the strings of <code>products</code> are <strong>unique</strong>.</li>
-	<li><code>products[i]</code> consists of lowercase English letters.</li>
-	<li><code>1 &lt;= searchWord.length &lt;= 1000</code></li>
-	<li><code>searchWord</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Brute force is a good choice because length of the string is ≤ 1000.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Binary search the answer.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use Trie data structure to store the best three matching. Traverse the Trie.
-</details>
diff --git a/problems/seat-reservation-manager/README.md b/problems/seat-reservation-manager/README.md
deleted file mode 100644
index 83f878644..000000000
--- a/problems/seat-reservation-manager/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../replace-all-digits-with-characters "Replace All Digits with Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-element-after-decreasing-and-rearranging "Maximum Element After Decreasing and Rearranging")
-
-## [1845. Seat Reservation Manager (Medium)](https://leetcode.com/problems/seat-reservation-manager "座位预约管理系统")
-
-<p>Design a system that manages the reservation state of <code>n</code> seats that are numbered from <code>1</code> to <code>n</code>.</p>
-
-<p>Implement the <code>SeatManager</code> class:</p>
-
-<ul>
-	<li><code>SeatManager(int n)</code> Initializes a <code>SeatManager</code> object that will manage <code>n</code> seats numbered from <code>1</code> to <code>n</code>. All seats are initially available.</li>
-	<li><code>int reserve()</code> Fetches the <strong>smallest-numbered</strong> unreserved seat, reserves it, and returns its number.</li>
-	<li><code>void unreserve(int seatNumber)</code> Unreserves the seat with the given <code>seatNumber</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;SeatManager&quot;, &quot;reserve&quot;, &quot;reserve&quot;, &quot;unreserve&quot;, &quot;reserve&quot;, &quot;reserve&quot;, &quot;reserve&quot;, &quot;reserve&quot;, &quot;unreserve&quot;]
-[[5], [], [], [2], [], [], [], [], [5]]
-<strong>Output</strong>
-[null, 1, 2, null, 2, 3, 4, 5, null]
-
-<strong>Explanation</strong>
-SeatManager seatManager = new SeatManager(5); // Initializes a SeatManager with 5 seats.
-seatManager.reserve();    // All seats are available, so return the lowest numbered seat, which is 1.
-seatManager.reserve();    // The available seats are [2,3,4,5], so return the lowest of them, which is 2.
-seatManager.unreserve(2); // Unreserve seat 2, so now the available seats are [2,3,4,5].
-seatManager.reserve();    // The available seats are [2,3,4,5], so return the lowest of them, which is 2.
-seatManager.reserve();    // The available seats are [3,4,5], so return the lowest of them, which is 3.
-seatManager.reserve();    // The available seats are [4,5], so return the lowest of them, which is 4.
-seatManager.reserve();    // The only available seat is seat 5, so return 5.
-seatManager.unreserve(5); // Unreserve seat 5, so now the available seats are [5].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= seatNumber &lt;= n</code></li>
-	<li>For each call to <code>reserve</code>, it is guaranteed that there will be at least one unreserved seat.</li>
-	<li>For each call to <code>unreserve</code>, it is guaranteed that <code>seatNumber</code> will be reserved.</li>
-	<li>At most <code>10<sup>5</sup></code> calls <strong>in total</strong> will be made to <code>reserve</code> and <code>unreserve</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You need a data structure that maintains the states of the seats. This data structure should also allow you to get the first available seat and flip the state of a seat in a reasonable time.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can let the data structure contain the available seats. Then you want to be able to get the lowest element and erase an element, in a reasonable time.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Ordered sets support these operations.
-</details>
diff --git a/problems/second-degree-follower/README.md b/problems/second-degree-follower/README.md
deleted file mode 100644
index da3878fbb..000000000
--- a/problems/second-degree-follower/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-distance-in-a-line "Shortest Distance in a Line")
-　　　　　　　　　　　　　　　　
-[Next >](../average-salary-departments-vs-company "Average Salary: Departments VS Company")
-
-## [614. Second Degree Follower (Medium)](https://leetcode.com/problems/second-degree-follower "二级关注者")
-
-<p>In facebook, there is a <code>follow</code> table with two columns: <b>followee</b>, <b>follower</b>.</p>
-
-<p>Please write a sql query to get the amount of each follower&rsquo;s follower if he/she has one.</p>
-
-<p>For example:</p>
-
-<pre>
-+-------------+------------+
-| followee    | follower   |
-+-------------+------------+
-|     A       |     B      |
-|     B       |     C      |
-|     B       |     D      |
-|     D       |     E      |
-+-------------+------------+
-</pre>
-should output:
-
-<pre>
-+-------------+------------+
-| follower    | num        |
-+-------------+------------+
-|     B       |  2         |
-|     D       |  1         |
-+-------------+------------+
-</pre>
-<b>Explaination:</b><br />
-Both B and D exist in the follower list, when as a followee, B&#39;s follower is C and D, and D&#39;s follower is E. A does not exist in follower list.
-<p>&nbsp;</p>
-
-<p>&nbsp;</p>
-<b>Note:</b><br />
-Followee would not follow himself/herself in all cases.<br />
-Please display the result in follower&#39;s alphabet order.
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/second-degree-follower/mysql_schemas.sql b/problems/second-degree-follower/mysql_schemas.sql
deleted file mode 100644
index 1dbb57626..000000000
--- a/problems/second-degree-follower/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Follow (followee varchar(255), follower varchar(255));
-Truncate table Follow;
-insert into Follow (followee, follower) values ('Alice', 'Bob');
-insert into Follow (followee, follower) values ('Bob', 'Cena');
-insert into Follow (followee, follower) values ('Bob', 'Donald');
-insert into Follow (followee, follower) values ('Donald', 'Edward');
diff --git a/problems/second-degree-follower/second_degree_follower.sql b/problems/second-degree-follower/second_degree_follower.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/second-degree-follower/second_degree_follower.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/second-highest-salary/README.md b/problems/second-highest-salary/README.md
deleted file mode 100644
index 6cb8a3e24..000000000
--- a/problems/second-highest-salary/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../combine-two-tables "Combine Two Tables")
-　　　　　　　　　　　　　　　　
-[Next >](../nth-highest-salary "Nth Highest Salary")
-
-## [176. Second Highest Salary (Medium)](https://leetcode.com/problems/second-highest-salary "第二高的薪水")
-
-<p>Table: <code>Employee</code></p>
-
-<pre>
-+-------------+------+
-| Column Name | Type |
-+-------------+------+
-| id          | int  |
-| salary      | int  |
-+-------------+------+
-id is the primary key column for this table.
-Each row of this table contains information about the salary of an employee.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to report the second highest salary from the <code>Employee</code> table. If there is no second highest salary, the query should report <code>null</code>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Employee table:
-+----+--------+
-| id | salary |
-+----+--------+
-| 1  | 100    |
-| 2  | 200    |
-| 3  | 300    |
-+----+--------+
-<strong>Output:</strong> 
-+---------------------+
-| SecondHighestSalary |
-+---------------------+
-| 200                 |
-+---------------------+
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Employee table:
-+----+--------+
-| id | salary |
-+----+--------+
-| 1  | 100    |
-+----+--------+
-<strong>Output:</strong> 
-+---------------------+
-| SecondHighestSalary |
-+---------------------+
-| null                |
-+---------------------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/second-highest-salary/mysql_schemas.sql b/problems/second-highest-salary/mysql_schemas.sql
deleted file mode 100644
index f98a8511a..000000000
--- a/problems/second-highest-salary/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create table If Not Exists Employee (id int, salary int);
-Truncate table Employee;
-insert into Employee (id, salary) values ('1', '100');
-insert into Employee (id, salary) values ('2', '200');
-insert into Employee (id, salary) values ('3', '300');
diff --git a/problems/second-highest-salary/second_highest_salary.sql b/problems/second-highest-salary/second_highest_salary.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/second-highest-salary/second_highest_salary.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/second-largest-digit-in-a-string/README.md b/problems/second-largest-digit-in-a-string/README.md
deleted file mode 100644
index e50360bbb..000000000
--- a/problems/second-largest-digit-in-a-string/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rearrange-products-table "Rearrange Products Table")
-　　　　　　　　　　　　　　　　
-[Next >](../design-authentication-manager "Design Authentication Manager")
-
-## [1796. Second Largest Digit in a String (Easy)](https://leetcode.com/problems/second-largest-digit-in-a-string "字符串中第二大的数字")
-
-<p>Given an alphanumeric string <code>s</code>, return <em>the <strong>second largest</strong> numerical digit that appears in </em><code>s</code><em>, or </em><code>-1</code><em> if it does not exist</em>.</p>
-
-<p>An <strong>alphanumeric</strong><strong> </strong>string is a string consisting of lowercase English letters and digits.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;dfa12321afd&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The digits that appear in s are [1, 2, 3]. The second largest digit is 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc1111&quot;
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> The digits that appear in s are [1]. There is no second largest digit. 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 500</code></li>
-	<li><code>s</code> consists of only lowercase English letters and/or digits.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First of all, get the distinct characters since we are only interested in those
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let's note that there might not be any digits.
-</details>
diff --git a/problems/second-minimum-node-in-a-binary-tree/README.md b/problems/second-minimum-node-in-a-binary-tree/README.md
deleted file mode 100644
index 3dc88a88f..000000000
--- a/problems/second-minimum-node-in-a-binary-tree/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-swap "Maximum Swap")
-　　　　　　　　　　　　　　　　
-[Next >](../bulb-switcher-ii "Bulb Switcher II")
-
-## [671. Second Minimum Node In a Binary Tree (Easy)](https://leetcode.com/problems/second-minimum-node-in-a-binary-tree "二叉树中第二小的节点")
-
-<p>Given a non-empty special binary tree consisting of nodes with the non-negative value, where each node in this tree has exactly <code>two</code> or <code>zero</code> sub-node. If the node has two sub-nodes, then this node&#39;s value is the smaller value among its two sub-nodes. More formally, the property&nbsp;<code>root.val = min(root.left.val, root.right.val)</code>&nbsp;always holds.</p>
-
-<p>Given such a binary tree, you need to output the <b>second minimum</b> value in the set made of all the nodes&#39; value in the whole tree.</p>
-
-<p>If no such second minimum value exists, output -1 instead.</p>
-
-<p>&nbsp;</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/15/smbt1.jpg" style="width: 431px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [2,2,5,null,null,5,7]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The smallest value is 2, the second smallest value is 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/15/smbt2.jpg" style="width: 321px; height: 182px;" />
-<pre>
-<strong>Input:</strong> root = [2,2,2]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> The smallest value is 2, but there isn&#39;t any second smallest value.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 25]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>root.val == min(root.left.val, root.right.val)</code>&nbsp;for each internal node of the tree.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Kth Smallest Element in a BST](../kth-smallest-element-in-a-bst) (Medium)
diff --git a/problems/second-minimum-node-in-a-binary-tree/second_minimum_node_in_a_binary_tree.go b/problems/second-minimum-node-in-a-binary-tree/second_minimum_node_in_a_binary_tree.go
deleted file mode 100644
index 392972c08..000000000
--- a/problems/second-minimum-node-in-a-binary-tree/second_minimum_node_in_a_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem671
diff --git a/problems/second-minimum-node-in-a-binary-tree/second_minimum_node_in_a_binary_tree_test.go b/problems/second-minimum-node-in-a-binary-tree/second_minimum_node_in_a_binary_tree_test.go
deleted file mode 100644
index 392972c08..000000000
--- a/problems/second-minimum-node-in-a-binary-tree/second_minimum_node_in_a_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem671
diff --git a/problems/second-minimum-time-to-reach-destination/README.md b/problems/second-minimum-time-to-reach-destination/README.md
deleted file mode 100644
index 6511ed733..000000000
--- a/problems/second-minimum-time-to-reach-destination/README.md
+++ /dev/null
@@ -1,94 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-number-of-maximum-bitwise-or-subsets "Count Number of Maximum Bitwise-OR Subsets")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-linked-list-already-sorted-using-absolute-values "Sort Linked List Already Sorted Using Absolute Values")
-
-## [2045. Second Minimum Time to Reach Destination (Hard)](https://leetcode.com/problems/second-minimum-time-to-reach-destination "到达目的地的第二短时间")
-
-<p>A city is represented as a <strong>bi-directional connected</strong> graph with <code>n</code> vertices where each vertex is labeled from <code>1</code> to <code>n</code> (<strong>inclusive</strong>). The edges in the graph are represented as a 2D integer array <code>edges</code>, where each <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> denotes a bi-directional edge between vertex <code>u<sub>i</sub></code> and vertex <code>v<sub>i</sub></code>. Every vertex pair is connected by <strong>at most one</strong> edge, and no vertex has an edge to itself. The time taken to traverse any edge is <code>time</code> minutes.</p>
-
-<p>Each vertex has a traffic signal which changes its color from <strong>green</strong> to <strong>red</strong> and vice versa every&nbsp;<code>change</code> minutes. All signals change <strong>at the same time</strong>. You can enter a vertex at <strong>any time</strong>, but can leave a vertex <strong>only when the signal is green</strong>. You <strong>cannot wait </strong>at a vertex if the signal is <strong>green</strong>.</p>
-
-<p>The <strong>second minimum value</strong> is defined as the smallest value<strong> strictly larger </strong>than the minimum value.</p>
-
-<ul>
-	<li>For example the second minimum value of <code>[2, 3, 4]</code> is <code>3</code>, and the second minimum value of <code>[2, 2, 4]</code> is <code>4</code>.</li>
-</ul>
-
-<p>Given <code>n</code>, <code>edges</code>, <code>time</code>, and <code>change</code>, return <em>the <strong>second minimum time</strong> it will take to go from vertex </em><code>1</code><em> to vertex </em><code>n</code>.</p>
-
-<p><strong>Notes:</strong></p>
-
-<ul>
-	<li>You can go through any vertex <strong>any</strong> number of times, <strong>including</strong> <code>1</code> and <code>n</code>.</li>
-	<li>You can assume that when the journey <strong>starts</strong>, all signals have just turned <strong>green</strong>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/29/e1.png" style="width: 200px; height: 250px;" /> &emsp; &emsp; &emsp; &emsp;<img alt="" src="https://assets.leetcode.com/uploads/2021/09/29/e2.png" style="width: 200px; height: 250px;" />
-<pre>
-<strong>Input:</strong> n = 5, edges = [[1,2],[1,3],[1,4],[3,4],[4,5]], time = 3, change = 5
-<strong>Output:</strong> 13
-<strong>Explanation:</strong>
-The figure on the left shows the given graph.
-The blue path in the figure on the right is the minimum time path.
-The time taken is:
-- Start at 1, time elapsed=0
-- 1 -&gt; 4: 3 minutes, time elapsed=3
-- 4 -&gt; 5: 3 minutes, time elapsed=6
-Hence the minimum time needed is 6 minutes.
-
-The red path shows the path to get the second minimum time.
-- Start at 1, time elapsed=0
-- 1 -&gt; 3: 3 minutes, time elapsed=3
-- 3 -&gt; 4: 3 minutes, time elapsed=6
-- Wait at 4 for 4 minutes, time elapsed=10
-- 4 -&gt; 5: 3 minutes, time elapsed=13
-Hence the second minimum time is 13 minutes.      
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/29/eg2.png" style="width: 225px; height: 50px;" />
-<pre>
-<strong>Input:</strong> n = 2, edges = [[1,2]], time = 3, change = 2
-<strong>Output:</strong> 11
-<strong>Explanation:</strong>
-The minimum time path is 1 -&gt; 2 with time = 3 minutes.
-The second minimum time path is 1 -&gt; 2 -&gt; 1 -&gt; 2 with time = 11 minutes.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>n - 1 &lt;= edges.length &lt;= min(2 * 10<sup>4</sup>, n * (n - 1) / 2)</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>1 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt;= n</code></li>
-	<li><code>u<sub>i</sub> != v<sub>i</sub></code></li>
-	<li>There are no duplicate edges.</li>
-	<li>Each vertex can be reached directly or indirectly from every other vertex.</li>
-	<li><code>1 &lt;= time, change &lt;= 10<sup>3</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How much is change actually necessary while calculating the required path?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How many extra edges do we need to add to the shortest path?
-</details>
diff --git a/problems/self-crossing/README.md b/problems/self-crossing/README.md
deleted file mode 100644
index 39f96b944..000000000
--- a/problems/self-crossing/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../increasing-triplet-subsequence "Increasing Triplet Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-pairs "Palindrome Pairs")
-
-## [335. Self Crossing (Hard)](https://leetcode.com/problems/self-crossing "路径交叉")
-
-<p>You are given an array of integers <code>distance</code>.</p>
-
-<p>You start at point <code>(0,0)</code> on an <strong>X-Y</strong> plane and you move <code>distance[0]</code> meters to the north, then <code>distance[1]</code> meters to the west, <code>distance[2]</code> meters to the south, <code>distance[3]</code> meters to the east, and so on. In other words, after each move, your direction changes counter-clockwise.</p>
-
-<p>Return <code>true</code> if your path crosses itself, and <code>false</code> if it does not.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/14/selfcross1-plane.jpg" style="width: 400px; height: 435px;" />
-<pre>
-<strong>Input:</strong> distance = [2,1,1,2]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/14/selfcross2-plane.jpg" style="width: 400px; height: 435px;" />
-<pre>
-<strong>Input:</strong> distance = [1,2,3,4]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/14/selfcross3-plane.jpg" style="width: 400px; height: 435px;" />
-<pre>
-<strong>Input:</strong> distance = [1,1,1,1]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;=&nbsp;distance.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;=&nbsp;distance[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/self-crossing/self_crossing.go b/problems/self-crossing/self_crossing.go
deleted file mode 100644
index 5f35acb1c..000000000
--- a/problems/self-crossing/self_crossing.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem335
diff --git a/problems/self-crossing/self_crossing_test.go b/problems/self-crossing/self_crossing_test.go
deleted file mode 100644
index 5f35acb1c..000000000
--- a/problems/self-crossing/self_crossing_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem335
diff --git a/problems/self-dividing-numbers/README.md b/problems/self-dividing-numbers/README.md
deleted file mode 100644
index 8f26c17e0..000000000
--- a/problems/self-dividing-numbers/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-window-subsequence "Minimum Window Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../my-calendar-i "My Calendar I")
-
-## [728. Self Dividing Numbers (Easy)](https://leetcode.com/problems/self-dividing-numbers "自除数")
-
-<p>A <strong>self-dividing number</strong> is a number that is divisible by every digit it contains.</p>
-
-<ul>
-	<li>For example, <code>128</code> is <strong>a self-dividing number</strong> because <code>128 % 1 == 0</code>, <code>128 % 2 == 0</code>, and <code>128 % 8 == 0</code>.</li>
-</ul>
-
-<p>A <strong>self-dividing number</strong> is not allowed to contain the digit zero.</p>
-
-<p>Given two integers <code>left</code> and <code>right</code>, return <em>a list of all the <strong>self-dividing numbers</strong> in the range</em> <code>[left, right]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> left = 1, right = 22
-<strong>Output:</strong> [1,2,3,4,5,6,7,8,9,11,12,15,22]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> left = 47, right = 85
-<strong>Output:</strong> [48,55,66,77]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= left &lt;= right &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Perfect Number](../perfect-number) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each number in the range, check whether it is self dividing by converting that number to a character array (or string in Python), then checking that each digit is nonzero and divides the original number.
-</details>
diff --git a/problems/self-dividing-numbers/self_dividing_numbers.go b/problems/self-dividing-numbers/self_dividing_numbers.go
deleted file mode 100644
index 6726dae2e..000000000
--- a/problems/self-dividing-numbers/self_dividing_numbers.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem728
-
-func selfDividingNumbers(left int, right int) []int {
-	ans := make([]int, 0)
-flag:
-	for i := left; i <= right; i++ {
-		for x := i; x > 0; x /= 10 {
-			if d := x % 10; d == 0 || i%d != 0 {
-				continue flag
-			}
-		}
-		ans = append(ans, i)
-	}
-	return ans
-}
diff --git a/problems/self-dividing-numbers/self_dividing_numbers_test.go b/problems/self-dividing-numbers/self_dividing_numbers_test.go
deleted file mode 100644
index afefd547b..000000000
--- a/problems/self-dividing-numbers/self_dividing_numbers_test.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package problem728
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	left  int
-	right int
-	want  []int
-}
-
-func TestSelfDividingNumbers(t *testing.T) {
-	tests := [...]testType{
-		{
-			left:  1,
-			right: 22,
-			want:  []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 15, 22},
-		},
-	}
-	for _, tt := range tests {
-		got := selfDividingNumbers(tt.left, tt.right)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.left, tt.right, got, tt.want)
-		}
-	}
-}
diff --git a/problems/sell-diminishing-valued-colored-balls/README.md b/problems/sell-diminishing-valued-colored-balls/README.md
deleted file mode 100644
index e010dd174..000000000
--- a/problems/sell-diminishing-valued-colored-balls/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-deletions-to-make-character-frequencies-unique "Minimum Deletions to Make Character Frequencies Unique")
-　　　　　　　　　　　　　　　　
-[Next >](../create-sorted-array-through-instructions "Create Sorted Array through Instructions")
-
-## [1648. Sell Diminishing-Valued Colored Balls (Medium)](https://leetcode.com/problems/sell-diminishing-valued-colored-balls "销售价值减少的颜色球")
-
-<p>You have an <code>inventory</code> of different colored balls, and there is a customer that wants <code>orders</code> balls of <strong>any</strong> color.</p>
-
-<p>The customer weirdly values the colored balls. Each colored ball&#39;s value is the number of balls <strong>of that color&nbsp;</strong>you currently have in your <code>inventory</code>. For example, if you own <code>6</code> yellow balls, the customer would pay <code>6</code> for the first yellow ball. After the transaction, there are only <code>5</code> yellow balls left, so the next yellow ball is then valued at <code>5</code> (i.e., the value of the balls decreases as you sell more to the customer).</p>
-
-<p>You are given an integer array, <code>inventory</code>, where <code>inventory[i]</code> represents the number of balls of the <code>i<sup>th</sup></code> color that you initially own. You are also given an integer <code>orders</code>, which represents the total number of balls that the customer wants. You can sell the balls <strong>in any order</strong>.</p>
-
-<p>Return <em>the <strong>maximum</strong> total value that you can attain after selling </em><code>orders</code><em> colored balls</em>. As the answer may be too large, return it <strong>modulo </strong><code>10<sup>9 </sup>+ 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/jj.gif" style="width: 480px; height: 270px;" />
-<pre>
-<strong>Input:</strong> inventory = [2,5], orders = 4
-<strong>Output:</strong> 14
-<strong>Explanation:</strong> Sell the 1st color 1 time (2) and the 2nd color 3 times (5 + 4 + 3).
-The maximum total value is 2 + 5 + 4 + 3 = 14.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> inventory = [3,5], orders = 6
-<strong>Output:</strong> 19
-<strong>Explanation: </strong>Sell the 1st color 2 times (3 + 2) and the 2nd color 4 times (5 + 4 + 3 + 2).
-The maximum total value is 3 + 2 + 5 + 4 + 3 + 2 = 19.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= inventory.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= inventory[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= orders &lt;= min(sum(inventory[i]), 10<sup>9</sup>)</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Greedily sell the most expensive ball.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-There is some value k where all balls of value > k are sold, and some, (maybe 0) of balls of value k are sold.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use binary search to find this value k, and use maths to find the total sum.
-</details>
diff --git a/problems/sellers-with-no-sales/README.md b/problems/sellers-with-no-sales/README.md
deleted file mode 100644
index 3d659cfa6..000000000
--- a/problems/sellers-with-no-sales/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-servers-that-handled-most-number-of-requests "Find Servers That Handled Most Number of Requests")
-　　　　　　　　　　　　　　　　
-[Next >](../special-array-with-x-elements-greater-than-or-equal-x "Special Array With X Elements Greater Than or Equal X")
-
-## [1607. Sellers With No Sales (Easy)](https://leetcode.com/problems/sellers-with-no-sales "没有卖出的卖家")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Customer Who Visited but Did Not Make Any Transactions](../customer-who-visited-but-did-not-make-any-transactions) (Easy)
diff --git a/problems/sellers-with-no-sales/mysql_schemas.sql b/problems/sellers-with-no-sales/mysql_schemas.sql
deleted file mode 100644
index 4e56240ee..000000000
--- a/problems/sellers-with-no-sales/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create table If Not Exists Customer (customer_id int, customer_name varchar(20));
-Create table If Not Exists Orders (order_id int, sale_date date, order_cost int, customer_id int, seller_id int)
-;
-Create table If Not Exists Seller (seller_id int, seller_name varchar(20))
-;
-Truncate table Customer;
-insert into Customer (customer_id, customer_name) values ('101', 'Alice');
-insert into Customer (customer_id, customer_name) values ('102', 'Bob');
-insert into Customer (customer_id, customer_name) values ('103', 'Charlie');
-Truncate table Orders;
-insert into Orders (order_id, sale_date, order_cost, customer_id, seller_id) values ('1', '2020-03-01', '1500', '101', '1');
-insert into Orders (order_id, sale_date, order_cost, customer_id, seller_id) values ('2', '2020-05-25', '2400', '102', '2');
-insert into Orders (order_id, sale_date, order_cost, customer_id, seller_id) values ('3', '2019-05-25', '800', '101', '3');
-insert into Orders (order_id, sale_date, order_cost, customer_id, seller_id) values ('4', '2020-09-13', '1000', '103', '2');
-insert into Orders (order_id, sale_date, order_cost, customer_id, seller_id) values ('5', '2019-02-11', '700', '101', '2');
-Truncate table Seller;
-insert into Seller (seller_id, seller_name) values ('1', 'Daniel');
-insert into Seller (seller_id, seller_name) values ('2', 'Elizabeth');
-insert into Seller (seller_id, seller_name) values ('3', 'Frank');
diff --git a/problems/sentence-screen-fitting/README.md b/problems/sentence-screen-fitting/README.md
deleted file mode 100644
index e23dcefe5..000000000
--- a/problems/sentence-screen-fitting/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pacific-atlantic-water-flow "Pacific Atlantic Water Flow")
-　　　　　　　　　　　　　　　　
-[Next >](../battleships-in-a-board "Battleships in a Board")
-
-## [418. Sentence Screen Fitting (Medium)](https://leetcode.com/problems/sentence-screen-fitting "屏幕可显示句子的数量")
-
-<p>Given a <code>rows x cols</code> screen and a sentence represented by a list of <b>non-empty</b> words, find <b>how many times</b> the given sentence can be fitted on the screen.
-</p>
-
-<p><b>Note:</b>
-<ol>
-<li>A word cannot be split into two lines.</li>
-<li>The order of words in the sentence must remain unchanged.</li>
-<li>Two consecutive words <b>in a line</b> must be separated by a single space.</li>
-<li>Total words in the sentence won't exceed 100.</li>
-<li>Length of each word is greater than 0 and won't exceed 10.</li>
-<li>1 &le; rows, cols &le; 20,000.</li>
-</ol>
-</p>
-
-<p>
-<b>Example 1:</b> 
-<pre>
-<b>Input:</b>
-rows = 2, cols = 8, sentence = ["hello", "world"]
-
-<b>Output:</b> 
-1
-
-<b>Explanation:</b>
-hello---
-world---
-
-The character '-' signifies an empty space on the screen.
-</pre>
-</p>
-
-<p>
-<b>Example 2:</b> 
-<pre>
-<b>Input:</b>
-rows = 3, cols = 6, sentence = ["a", "bcd", "e"]
-
-<b>Output:</b> 
-2
-
-<b>Explanation:</b>
-a-bcd- 
-e-a---
-bcd-e-
-
-The character '-' signifies an empty space on the screen.
-</pre>
-</p>
-
-<p>
-<b>Example 3:</b> 
-<pre>
-<b>Input:</b>
-rows = 4, cols = 5, sentence = ["I", "had", "apple", "pie"]
-
-<b>Output:</b> 
-1
-
-<b>Explanation:</b>
-I-had
-apple
-pie-I
-had--
-
-The character '-' signifies an empty space on the screen.
-</pre>
-</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Minimum Cost to Separate Sentence Into Rows](../minimum-cost-to-separate-sentence-into-rows) (Medium)
diff --git a/problems/sentence-screen-fitting/sentence_screen_fitting.go b/problems/sentence-screen-fitting/sentence_screen_fitting.go
deleted file mode 100644
index 11b66a7b0..000000000
--- a/problems/sentence-screen-fitting/sentence_screen_fitting.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem418
diff --git a/problems/sentence-screen-fitting/sentence_screen_fitting_test.go b/problems/sentence-screen-fitting/sentence_screen_fitting_test.go
deleted file mode 100644
index 11b66a7b0..000000000
--- a/problems/sentence-screen-fitting/sentence_screen_fitting_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem418
diff --git a/problems/sentence-similarity-ii/README.md b/problems/sentence-similarity-ii/README.md
deleted file mode 100644
index ad783e0e6..000000000
--- a/problems/sentence-similarity-ii/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../parse-lisp-expression "Parse Lisp Expression")
-　　　　　　　　　　　　　　　　
-[Next >](../monotone-increasing-digits "Monotone Increasing Digits")
-
-## [737. Sentence Similarity II (Medium)](https://leetcode.com/problems/sentence-similarity-ii "句子相似性 II")
-
-<p>Given two sentences <code>words1, words2</code> (each represented as an array of strings), and a list of similar word pairs <code>pairs</code>, determine if two sentences are similar.</p>
-
-<p>For example, <code>words1 = [&quot;great&quot;, &quot;acting&quot;, &quot;skills&quot;]</code> and <code>words2 = [&quot;fine&quot;, &quot;drama&quot;, &quot;talent&quot;]</code> are similar, if the similar word pairs are <code>pairs = [[&quot;great&quot;, &quot;good&quot;], [&quot;fine&quot;, &quot;good&quot;], [&quot;acting&quot;,&quot;drama&quot;], [&quot;skills&quot;,&quot;talent&quot;]]</code>.</p>
-
-<p>Note that the similarity relation <b>is</b> transitive. For example, if &quot;great&quot; and &quot;good&quot; are similar, and &quot;fine&quot; and &quot;good&quot; are similar, then &quot;great&quot; and &quot;fine&quot; <b>are similar</b>.</p>
-
-<p>Similarity is also symmetric. For example, &quot;great&quot; and &quot;fine&quot; being similar is the same as &quot;fine&quot; and &quot;great&quot; being similar.</p>
-
-<p>Also, a word is always similar with itself. For example, the sentences <code>words1 = [&quot;great&quot;], words2 = [&quot;great&quot;], pairs = []</code> are similar, even though there are no specified similar word pairs.</p>
-
-<p>Finally, sentences can only be similar if they have the same number of words. So a sentence like <code>words1 = [&quot;great&quot;]</code> can never be similar to <code>words2 = [&quot;doubleplus&quot;,&quot;good&quot;]</code>.</p>
-
-<p><b>Note:</b></p>
-
-<ul>
-	<li>The length of <code>words1</code> and <code>words2</code> will not exceed <code>1000</code>.</li>
-	<li>The length of <code>pairs</code> will not exceed <code>2000</code>.</li>
-	<li>The length of each <code>pairs[i]</code> will be <code>2</code>.</li>
-	<li>The length of each <code>words[i]</code> and <code>pairs[i][j]</code> will be in the range <code>[1, 20]</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Number of Provinces](../number-of-provinces) (Medium)
-  1. [Accounts Merge](../accounts-merge) (Medium)
-  1. [Sentence Similarity](../sentence-similarity) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider the graphs where each pair in "pairs" is an edge.  Two words are similar if they are the same, or are in the same connected component of this graph.
-</details>
diff --git a/problems/sentence-similarity-ii/sentence_similarity_ii.go b/problems/sentence-similarity-ii/sentence_similarity_ii.go
deleted file mode 100644
index 85e42bdd4..000000000
--- a/problems/sentence-similarity-ii/sentence_similarity_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem737
diff --git a/problems/sentence-similarity-ii/sentence_similarity_ii_test.go b/problems/sentence-similarity-ii/sentence_similarity_ii_test.go
deleted file mode 100644
index 85e42bdd4..000000000
--- a/problems/sentence-similarity-ii/sentence_similarity_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem737
diff --git a/problems/sentence-similarity-iii/README.md b/problems/sentence-similarity-iii/README.md
deleted file mode 100644
index 45db111c7..000000000
--- a/problems/sentence-similarity-iii/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../determine-color-of-a-chessboard-square "Determine Color of a Chessboard Square")
-　　　　　　　　　　　　　　　　
-[Next >](../count-nice-pairs-in-an-array "Count Nice Pairs in an Array")
-
-## [1813. Sentence Similarity III (Medium)](https://leetcode.com/problems/sentence-similarity-iii "句子相似性 III")
-
-<p>A sentence is a list of words that are separated by a single space with no leading or trailing spaces. For example, <code>&quot;Hello World&quot;</code>, <code>&quot;HELLO&quot;</code>, <code>&quot;hello world hello world&quot;</code> are all sentences. Words consist of <strong>only</strong> uppercase and lowercase English letters.</p>
-
-<p>Two sentences <code>sentence1</code> and <code>sentence2</code> are <strong>similar</strong> if it is possible to insert an arbitrary sentence <strong>(possibly empty)</strong> inside one of these sentences such that the two sentences become equal. For example, <code>sentence1 = &quot;Hello my name is Jane&quot;</code> and <code>sentence2 = &quot;Hello Jane&quot;</code> can be made equal by inserting <code>&quot;my name is&quot;</code> between <code>&quot;Hello&quot;</code> and <code>&quot;Jane&quot;</code> in <code>sentence2</code>.</p>
-
-<p>Given two sentences <code>sentence1</code> and <code>sentence2</code>, return <code>true</code> <em>if </em><code>sentence1</code> <em>and </em><code>sentence2</code> <em>are similar.</em> Otherwise, return <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence1 = &quot;My name is Haley&quot;, sentence2 = &quot;My Haley&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> sentence2 can be turned to sentence1 by inserting &quot;name is&quot; between &quot;My&quot; and &quot;Haley&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence1 = &quot;of&quot;, sentence2 = &quot;A lot of words&quot;
-<strong>Output:</strong> false
-<strong>Explanation: </strong>No single sentence can be inserted inside one of the sentences to make it equal to the other.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> sentence1 = &quot;Eating right now&quot;, sentence2 = &quot;Eating&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> sentence2 can be turned to sentence1 by inserting &quot;right now&quot; at the end of the sentence.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= sentence1.length, sentence2.length &lt;= 100</code></li>
-	<li><code>sentence1</code> and <code>sentence2</code> consist of lowercase and uppercase English letters and spaces.</li>
-	<li>The words in <code>sentence1</code> and <code>sentence2</code> are separated by a single space.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-One way to look at it is to find one sentence as a concatenation of a prefix and suffix from the other sentence.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Get the longest common prefix between them and the longest common suffix.
-</details>
diff --git a/problems/sentence-similarity/README.md b/problems/sentence-similarity/README.md
deleted file mode 100644
index 4c2e329ba..000000000
--- a/problems/sentence-similarity/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flood-fill "Flood Fill")
-　　　　　　　　　　　　　　　　
-[Next >](../asteroid-collision "Asteroid Collision")
-
-## [734. Sentence Similarity (Easy)](https://leetcode.com/problems/sentence-similarity "句子相似性")
-
-<p>Given two sentences <code>words1, words2</code> (each represented as an array of strings), and a list of similar word pairs <code>pairs</code>, determine if two sentences are similar.</p>
-
-<p>For example, &quot;great acting skills&quot; and &quot;fine drama talent&quot; are similar, if the similar word pairs are <code>pairs = [[&quot;great&quot;, &quot;fine&quot;], [&quot;acting&quot;,&quot;drama&quot;], [&quot;skills&quot;,&quot;talent&quot;]]</code>.</p>
-
-<p>Note that the similarity relation is not transitive. For example, if &quot;great&quot; and &quot;fine&quot; are similar, and &quot;fine&quot; and &quot;good&quot; are similar, &quot;great&quot; and &quot;good&quot; are <b>not</b> necessarily similar.</p>
-
-<p>However, similarity is symmetric. For example, &quot;great&quot; and &quot;fine&quot; being similar is the same as &quot;fine&quot; and &quot;great&quot; being similar.</p>
-
-<p>Also, a word is always similar with itself. For example, the sentences <code>words1 = [&quot;great&quot;], words2 = [&quot;great&quot;], pairs = []</code> are similar, even though there are no specified similar word pairs.</p>
-
-<p>Finally, sentences can only be similar if they have the same number of words. So a sentence like <code>words1 = [&quot;great&quot;]</code> can never be similar to <code>words2 = [&quot;doubleplus&quot;,&quot;good&quot;]</code>.</p>
-
-<p><b>Note:</b></p>
-
-<ul>
-	<li>The length of <code>words1</code> and <code>words2</code> will not exceed <code>1000</code>.</li>
-	<li>The length of <code>pairs</code> will not exceed <code>2000</code>.</li>
-	<li>The length of each <code>pairs[i]</code> will be <code>2</code>.</li>
-	<li>The length of each <code>words[i]</code> and <code>pairs[i][j]</code> will be in the range <code>[1, 20]</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Number of Provinces](../number-of-provinces) (Medium)
-  1. [Accounts Merge](../accounts-merge) (Medium)
-  1. [Sentence Similarity II](../sentence-similarity-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Two words w1 and w2 are similar if and only if w1 == w2, (w1, w2) was a pair, or (w2, w1) was a pair.
-</details>
diff --git a/problems/sentence-similarity/sentence_similarity.go b/problems/sentence-similarity/sentence_similarity.go
deleted file mode 100644
index 48ceabac1..000000000
--- a/problems/sentence-similarity/sentence_similarity.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem734
diff --git a/problems/sentence-similarity/sentence_similarity_test.go b/problems/sentence-similarity/sentence_similarity_test.go
deleted file mode 100644
index 48ceabac1..000000000
--- a/problems/sentence-similarity/sentence_similarity_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem734
diff --git a/problems/sequence-reconstruction/README.md b/problems/sequence-reconstruction/README.md
deleted file mode 100644
index fab41cd33..000000000
--- a/problems/sequence-reconstruction/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../string-compression "String Compression")
-　　　　　　　　　　　　　　　　
-[Next >](../add-two-numbers-ii "Add Two Numbers II")
-
-## [444. Sequence Reconstruction (Medium)](https://leetcode.com/problems/sequence-reconstruction "序列重建")
-
-<p>Check whether the original sequence <code>org</code> can be uniquely reconstructed from the sequences in <code>seqs</code>. The <code>org</code> sequence is a permutation of the integers from 1 to n, with 1 &le; n &le; 10<sup>4</sup>. Reconstruction means building a shortest common supersequence of the sequences in <code>seqs</code> (i.e., a shortest sequence so that all sequences in <code>seqs</code> are subsequences of it). Determine whether there is only one sequence that can be reconstructed from <code>seqs</code> and it is the <code>org</code> sequence.</p>
-
-<p><b>Example 1:</b>
-<pre>
-<b>Input:</b>
-org: [1,2,3], seqs: [[1,2],[1,3]]
-
-<b>Output:</b>
-false
-
-<b>Explanation:</b>
-[1,2,3] is not the only one sequence that can be reconstructed, because [1,3,2] is also a valid sequence that can be reconstructed.
-</pre>
-</p>
-
-<p><b>Example 2:</b>
-<pre>
-<b>Input:</b>
-org: [1,2,3], seqs: [[1,2]]
-
-<b>Output:</b>
-false
-
-<b>Explanation:</b>
-The reconstructed sequence can only be [1,2].
-</pre>
-</p>
-
-<p><b>Example 3:</b>
-<pre>
-<b>Input:</b>
-org: [1,2,3], seqs: [[1,2],[1,3],[2,3]]
-
-<b>Output:</b>
-true
-
-<b>Explanation:</b>
-The sequences [1,2], [1,3], and [2,3] can uniquely reconstruct the original sequence [1,2,3].
-</pre>
-</p>
-
-<p><b>Example 4:</b>
-<pre>
-<b>Input:</b>
-org: [4,1,5,2,6,3], seqs: [[5,2,6,3],[4,1,5,2]]
-
-<b>Output:</b>
-true
-</pre>
-</p>
-
-<p>
-<b><font color="red">UPDATE (2017/1/8):</font></b><br />
-The <i>seqs</i> parameter had been changed to a list of list of strings (instead of a 2d array of strings). Please reload the code definition to get the latest changes.
-</p>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Course Schedule II](../course-schedule-ii) (Medium)
diff --git a/problems/sequence-reconstruction/sequence_reconstruction.go b/problems/sequence-reconstruction/sequence_reconstruction.go
deleted file mode 100644
index f14ca7f03..000000000
--- a/problems/sequence-reconstruction/sequence_reconstruction.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem444
diff --git a/problems/sequence-reconstruction/sequence_reconstruction_test.go b/problems/sequence-reconstruction/sequence_reconstruction_test.go
deleted file mode 100644
index f14ca7f03..000000000
--- a/problems/sequence-reconstruction/sequence_reconstruction_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem444
diff --git a/problems/sequential-digits/README.md b/problems/sequential-digits/README.md
deleted file mode 100644
index 9dfeeb487..000000000
--- a/problems/sequential-digits/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../convert-binary-number-in-a-linked-list-to-integer "Convert Binary Number in a Linked List to Integer")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold "Maximum Side Length of a Square with Sum Less than or Equal to Threshold")
-
-## [1291. Sequential Digits (Medium)](https://leetcode.com/problems/sequential-digits "顺次数")
-
-<p>An&nbsp;integer has <em>sequential digits</em> if and only if each digit in the number is one more than the previous digit.</p>
-
-<p>Return a <strong>sorted</strong> list of all the integers&nbsp;in the range <code>[low, high]</code>&nbsp;inclusive that have sequential digits.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> low = 100, high = 300
-<strong>Output:</strong> [123,234]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> low = 1000, high = 13000
-<strong>Output:</strong> [1234,2345,3456,4567,5678,6789,12345]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>10 &lt;= low &lt;= high &lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Generate all numbers with sequential digits and check if they are in the given range.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Fix the starting digit then do a recursion that tries to append all valid digits.
-</details>
diff --git a/problems/sequentially-ordinal-rank-tracker/README.md b/problems/sequentially-ordinal-rank-tracker/README.md
deleted file mode 100644
index 4b1402419..000000000
--- a/problems/sequentially-ordinal-rank-tracker/README.md
+++ /dev/null
@@ -1,113 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../detonate-the-maximum-bombs "Detonate the Maximum Bombs")
-　　　　　　　　　　　　　　　　
-[Next >](../rings-and-rods "Rings and Rods")
-
-## [2102. Sequentially Ordinal Rank Tracker (Hard)](https://leetcode.com/problems/sequentially-ordinal-rank-tracker "序列顺序查询")
-
-<p>A scenic location is represented by its <code>name</code> and attractiveness <code>score</code>, where <code>name</code> is a <strong>unique</strong> string among all locations and <code>score</code> is an integer. Locations can be ranked from the best to the worst. The <strong>higher</strong> the score, the better the location. If the scores of two locations are equal, then the location with the <strong>lexicographically smaller</strong> name is better.</p>
-
-<p>You are building a system that tracks the ranking of locations with the system initially starting with no locations. It supports:</p>
-
-<ul>
-	<li><strong>Adding</strong> scenic locations, <strong>one at a time</strong>.</li>
-	<li><strong>Querying</strong> the <code>i<sup>th</sup></code> <strong>best</strong> location of <strong>all locations already added</strong>, where <code>i</code> is the number of times the system has been queried (including the current query).
-	<ul>
-		<li>For example, when the system is queried for the <code>4<sup>th</sup></code> time, it returns the <code>4<sup>th</sup></code> best location of all locations already added.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Note that the test data are generated so that <strong>at any time</strong>, the number of queries <strong>does not exceed</strong> the number of locations added to the system.</p>
-
-<p>Implement the <code>SORTracker</code> class:</p>
-
-<ul>
-	<li><code>SORTracker()</code> Initializes the tracker system.</li>
-	<li><code>void add(string name, int score)</code> Adds a scenic location with <code>name</code> and <code>score</code> to the system.</li>
-	<li><code>string get()</code> Queries and returns the <code>i<sup>th</sup></code> best location, where <code>i</code> is the number of times this method has been invoked (including this invocation).</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;SORTracker&quot;, &quot;add&quot;, &quot;add&quot;, &quot;get&quot;, &quot;add&quot;, &quot;get&quot;, &quot;add&quot;, &quot;get&quot;, &quot;add&quot;, &quot;get&quot;, &quot;add&quot;, &quot;get&quot;, &quot;get&quot;]
-[[], [&quot;bradford&quot;, 2], [&quot;branford&quot;, 3], [], [&quot;alps&quot;, 2], [], [&quot;orland&quot;, 2], [], [&quot;orlando&quot;, 3], [], [&quot;alpine&quot;, 2], [], []]
-<strong>Output</strong>
-[null, null, null, &quot;branford&quot;, null, &quot;alps&quot;, null, &quot;bradford&quot;, null, &quot;bradford&quot;, null, &quot;bradford&quot;, &quot;orland&quot;]
-
-<strong>Explanation</strong>
-SORTracker tracker = new SORTracker(); // Initialize the tracker system.
-tracker.add(&quot;bradford&quot;, 2); // Add location with name=&quot;bradford&quot; and score=2 to the system.
-tracker.add(&quot;branford&quot;, 3); // Add location with name=&quot;branford&quot; and score=3 to the system.
-tracker.get();              // The sorted locations, from best to worst, are: branford, bradford.
-                            // Note that branford precedes bradford due to its <strong>higher score</strong> (3 &gt; 2).
-                            // This is the 1<sup>st</sup> time get() is called, so return the best location: &quot;branford&quot;.
-tracker.add(&quot;alps&quot;, 2);     // Add location with name=&quot;alps&quot; and score=2 to the system.
-tracker.get();              // Sorted locations: branford, alps, bradford.
-                            // Note that alps precedes bradford even though they have the same score (2).
-                            // This is because &quot;alps&quot; is <strong>lexicographically smaller</strong> than &quot;bradford&quot;.
-                            // Return the 2<sup>nd</sup> best location &quot;alps&quot;, as it is the 2<sup>nd</sup> time get() is called.
-tracker.add(&quot;orland&quot;, 2);   // Add location with name=&quot;orland&quot; and score=2 to the system.
-tracker.get();              // Sorted locations: branford, alps, bradford, orland.
-                            // Return &quot;bradford&quot;, as it is the 3<sup>rd</sup> time get() is called.
-tracker.add(&quot;orlando&quot;, 3);  // Add location with name=&quot;orlando&quot; and score=3 to the system.
-tracker.get();              // Sorted locations: branford, orlando, alps, bradford, orland.
-                            // Return &quot;bradford&quot;.
-tracker.add(&quot;alpine&quot;, 2);   // Add location with name=&quot;alpine&quot; and score=2 to the system.
-tracker.get();              // Sorted locations: branford, orlando, alpine, alps, bradford, orland.
-                            // Return &quot;bradford&quot;.
-tracker.get();              // Sorted locations: branford, orlando, alpine, alps, bradford, orland.
-                            // Return &quot;orland&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>name</code> consists of lowercase English letters, and is unique among all locations.</li>
-	<li><code>1 &lt;= name.length &lt;= 10</code></li>
-	<li><code>1 &lt;= score &lt;= 10<sup>5</sup></code></li>
-	<li>At any time, the number of calls to <code>get</code> does not exceed the number of calls to <code>add</code>.</li>
-	<li>At most <code>4 * 10<sup>4</sup></code> calls <strong>in total</strong> will be made to <code>add</code> and <code>get</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the problem were to find the median of a stream of scenery locations while they are being added, can you solve it?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can use a similar approach as an optimization to avoid repeated sorting.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Employ two heaps: left heap and right heap. The left heap is a max-heap, and the right heap is a min-heap. The size of the left heap is k + 1 (best locations), where k is the number of times the get method was invoked. The other locations are maintained in the right heap.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Every time when add is being called, we add it to the left heap. If the size of the left heap exceeds k + 1, we move the head element to the right heap.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-When the get method is invoked again (the k + 1 time it is invoked), we can return the head element of the left heap. But before returning it, if the right heap is not empty, we maintain the left heap to have the best k + 2 items by moving the best location from the right heap to the left heap.
-</details>
diff --git a/problems/serialize-and-deserialize-binary-tree/README.md b/problems/serialize-and-deserialize-binary-tree/README.md
deleted file mode 100644
index 4160e5f76..000000000
--- a/problems/serialize-and-deserialize-binary-tree/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-meeting-point "Best Meeting Point")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-longest-consecutive-sequence "Binary Tree Longest Consecutive Sequence")
-
-## [297. Serialize and Deserialize Binary Tree (Hard)](https://leetcode.com/problems/serialize-and-deserialize-binary-tree "二叉树的序列化与反序列化")
-
-<p>Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.</p>
-
-<p>Design an algorithm to serialize and deserialize a binary tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary tree can be serialized to a string and this string can be deserialized to the original tree structure.</p>
-
-<p><strong>Clarification:</strong> The input/output format is the same as <a href="/faq/#binary-tree">how LeetCode serializes a binary tree</a>. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/serdeser.jpg" style="width: 442px; height: 324px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,null,null,4,5]
-<strong>Output:</strong> [1,2,3,null,null,4,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,2]
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Encode and Decode Strings](../encode-and-decode-strings) (Medium)
-  1. [Serialize and Deserialize BST](../serialize-and-deserialize-bst) (Medium)
-  1. [Find Duplicate Subtrees](../find-duplicate-subtrees) (Medium)
-  1. [Serialize and Deserialize N-ary Tree](../serialize-and-deserialize-n-ary-tree) (Hard)
diff --git a/problems/serialize-and-deserialize-binary-tree/serialize_and_deserialize_binary_tree.go b/problems/serialize-and-deserialize-binary-tree/serialize_and_deserialize_binary_tree.go
deleted file mode 100644
index 16664e22a..000000000
--- a/problems/serialize-and-deserialize-binary-tree/serialize_and_deserialize_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem297
diff --git a/problems/serialize-and-deserialize-binary-tree/serialize_and_deserialize_binary_tree.py b/problems/serialize-and-deserialize-binary-tree/serialize_and_deserialize_binary_tree.py
deleted file mode 100755
index 2b769700c..000000000
--- a/problems/serialize-and-deserialize-binary-tree/serialize_and_deserialize_binary_tree.py
+++ /dev/null
@@ -1,30 +0,0 @@
-#!/usr/bin/env python
-
-# Definition for a binary tree node.
-# class TreeNode(object):
-#     def __init__(self, x):
-#         self.val = x
-#         self.left = None
-#         self.right = None
-
-class Codec:
-
-    def serialize(self, root):
-        """Encodes a tree to a single string.
-        
-        :type root: TreeNode
-        :rtype: str
-        """
-        
-
-    def deserialize(self, data):
-        """Decodes your encoded data to tree.
-        
-        :type data: str
-        :rtype: TreeNode
-        """
-        
-
-# Your Codec object will be instantiated and called as such:
-# codec = Codec()
-# codec.deserialize(codec.serialize(root))
\ No newline at end of file
diff --git a/problems/serialize-and-deserialize-binary-tree/serialize_and_deserialize_binary_tree_test.go b/problems/serialize-and-deserialize-binary-tree/serialize_and_deserialize_binary_tree_test.go
deleted file mode 100644
index 16664e22a..000000000
--- a/problems/serialize-and-deserialize-binary-tree/serialize_and_deserialize_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem297
diff --git a/problems/serialize-and-deserialize-bst/README.md b/problems/serialize-and-deserialize-bst/README.md
deleted file mode 100644
index 806fb28dd..000000000
--- a/problems/serialize-and-deserialize-bst/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-all-numbers-disappeared-in-an-array "Find All Numbers Disappeared in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-node-in-a-bst "Delete Node in a BST")
-
-## [449. Serialize and Deserialize BST (Medium)](https://leetcode.com/problems/serialize-and-deserialize-bst "序列化和反序列化二叉搜索树")
-
-<p>Serialization is converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.</p>
-
-<p>Design an algorithm to serialize and deserialize a <b>binary search tree</b>. There is no restriction on how your serialization/deserialization algorithm should work. You need to ensure that a binary search tree can be serialized to a string, and this string can be deserialized to the original tree structure.</p>
-
-<p><b>The encoded string should be as compact as possible.</b></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> root = [2,1,3]
-<strong>Output:</strong> [2,1,3]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> root = []
-<strong>Output:</strong> []
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-	<li>The input tree is <strong>guaranteed</strong> to be a binary search tree.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Serialize and Deserialize Binary Tree](../serialize-and-deserialize-binary-tree) (Hard)
-  1. [Find Duplicate Subtrees](../find-duplicate-subtrees) (Medium)
-  1. [Serialize and Deserialize N-ary Tree](../serialize-and-deserialize-n-ary-tree) (Hard)
diff --git a/problems/serialize-and-deserialize-bst/serialize_and_deserialize_bst.go b/problems/serialize-and-deserialize-bst/serialize_and_deserialize_bst.go
deleted file mode 100644
index b46c99fd2..000000000
--- a/problems/serialize-and-deserialize-bst/serialize_and_deserialize_bst.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem449
diff --git a/problems/serialize-and-deserialize-bst/serialize_and_deserialize_bst.py b/problems/serialize-and-deserialize-bst/serialize_and_deserialize_bst.py
deleted file mode 100755
index 2b769700c..000000000
--- a/problems/serialize-and-deserialize-bst/serialize_and_deserialize_bst.py
+++ /dev/null
@@ -1,30 +0,0 @@
-#!/usr/bin/env python
-
-# Definition for a binary tree node.
-# class TreeNode(object):
-#     def __init__(self, x):
-#         self.val = x
-#         self.left = None
-#         self.right = None
-
-class Codec:
-
-    def serialize(self, root):
-        """Encodes a tree to a single string.
-        
-        :type root: TreeNode
-        :rtype: str
-        """
-        
-
-    def deserialize(self, data):
-        """Decodes your encoded data to tree.
-        
-        :type data: str
-        :rtype: TreeNode
-        """
-        
-
-# Your Codec object will be instantiated and called as such:
-# codec = Codec()
-# codec.deserialize(codec.serialize(root))
\ No newline at end of file
diff --git a/problems/serialize-and-deserialize-bst/serialize_and_deserialize_bst_test.go b/problems/serialize-and-deserialize-bst/serialize_and_deserialize_bst_test.go
deleted file mode 100644
index b46c99fd2..000000000
--- a/problems/serialize-and-deserialize-bst/serialize_and_deserialize_bst_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem449
diff --git a/problems/serialize-and-deserialize-n-ary-tree/README.md b/problems/serialize-and-deserialize-n-ary-tree/README.md
deleted file mode 100644
index cacfe9ae5..000000000
--- a/problems/serialize-and-deserialize-n-ary-tree/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../construct-quad-tree "Construct Quad Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../n-ary-tree-level-order-traversal "N-ary Tree Level Order Traversal")
-
-## [428. Serialize and Deserialize N-ary Tree (Hard)](https://leetcode.com/problems/serialize-and-deserialize-n-ary-tree "序列化和反序列化 N 叉树")
-
-<p>Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.</p>
-
-<p>Design an algorithm to serialize and deserialize an N-ary tree. An N-ary tree is a rooted tree in which each node has no more than N children. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that an N-ary tree can be serialized to a string and this string can be deserialized to the original tree structure.</p>
-
-<p>For example, you may serialize the following <code>3-ary</code> tree</p>
-
-<p>&nbsp;</p>
-
-<p><img src="https://assets.leetcode.com/uploads/2018/10/12/narytreeexample.png" style="width: 100%; max-width: 300px;" /></p>
-
-<p>&nbsp;</p>
-
-<p>as <code>[1 [3[5 6] 2 4]]</code>. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>N</code> is in the range of <code> [1, 1000]</code></li>
-	<li>Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.</li>
-</ol>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Serialize and Deserialize Binary Tree](../serialize-and-deserialize-binary-tree) (Hard)
-  1. [Serialize and Deserialize BST](../serialize-and-deserialize-bst) (Medium)
-  1. [Encode N-ary Tree to Binary Tree](../encode-n-ary-tree-to-binary-tree) (Hard)
diff --git a/problems/serialize-and-deserialize-n-ary-tree/serialize_and_deserialize_n_ary_tree.go b/problems/serialize-and-deserialize-n-ary-tree/serialize_and_deserialize_n_ary_tree.go
deleted file mode 100644
index d566dc0e3..000000000
--- a/problems/serialize-and-deserialize-n-ary-tree/serialize_and_deserialize_n_ary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem428
diff --git a/problems/serialize-and-deserialize-n-ary-tree/serialize_and_deserialize_n_ary_tree_test.go b/problems/serialize-and-deserialize-n-ary-tree/serialize_and_deserialize_n_ary_tree_test.go
deleted file mode 100644
index d566dc0e3..000000000
--- a/problems/serialize-and-deserialize-n-ary-tree/serialize_and_deserialize_n_ary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem428
diff --git a/problems/set-intersection-size-at-least-two/README.md b/problems/set-intersection-size-at-least-two/README.md
deleted file mode 100644
index 948d7ff0a..000000000
--- a/problems/set-intersection-size-at-least-two/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pyramid-transition-matrix "Pyramid Transition Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../bold-words-in-string "Bold Words in String")
-
-## [757. Set Intersection Size At Least Two (Hard)](https://leetcode.com/problems/set-intersection-size-at-least-two "设置交集大小至少为2")
-
-<p>An integer interval <code>[a, b]</code> (for integers <code>a &lt; b</code>) is a set of all consecutive integers from <code>a</code> to <code>b</code>, including <code>a</code> and <code>b</code>.</p>
-
-<p>Find the minimum size of a set S such that for every integer interval A in <code>intervals</code>, the intersection of S with A has a size of at least two.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,3],[1,4],[2,5],[3,5]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Consider the set S = {2, 3, 4}.  For each interval, there are at least 2 elements from S in the interval.
-Also, there isn&#39;t a smaller size set that fulfills the above condition.
-Thus, we output the size of this set, which is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> intervals = [[1,2],[2,3],[2,4],[4,5]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> An example of a minimum sized set is {1, 2, 3, 4, 5}.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= intervals.length &lt;= 3000</code></li>
-	<li><code>intervals[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub> &lt;&nbsp;b<sub>i</sub> &lt;= 10<sup>8</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/set-intersection-size-at-least-two/set_intersection_size_at_least_two.go b/problems/set-intersection-size-at-least-two/set_intersection_size_at_least_two.go
deleted file mode 100644
index 23f612d57..000000000
--- a/problems/set-intersection-size-at-least-two/set_intersection_size_at_least_two.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem757
diff --git a/problems/set-intersection-size-at-least-two/set_intersection_size_at_least_two_test.go b/problems/set-intersection-size-at-least-two/set_intersection_size_at_least_two_test.go
deleted file mode 100644
index 23f612d57..000000000
--- a/problems/set-intersection-size-at-least-two/set_intersection_size_at_least_two_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem757
diff --git a/problems/set-matrix-zeroes/README.md b/problems/set-matrix-zeroes/README.md
deleted file mode 100644
index f3c767924..000000000
--- a/problems/set-matrix-zeroes/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../edit-distance "Edit Distance")
-　　　　　　　　　　　　　　　　
-[Next >](../search-a-2d-matrix "Search a 2D Matrix")
-
-## [73. Set Matrix Zeroes (Medium)](https://leetcode.com/problems/set-matrix-zeroes "矩阵置零")
-
-<p>Given an <code>m x n</code> integer matrix <code>matrix</code>, if an element is <code>0</code>, set its entire row and column to <code>0</code>&#39;s.</p>
-
-<p>You must do it <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank">in place</a>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/17/mat1.jpg" style="width: 450px; height: 169px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,1,1],[1,0,1],[1,1,1]]
-<strong>Output:</strong> [[1,0,1],[0,0,0],[1,0,1]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/08/17/mat2.jpg" style="width: 450px; height: 137px;" />
-<pre>
-<strong>Input:</strong> matrix = [[0,1,2,0],[3,4,5,2],[1,3,1,5]]
-<strong>Output:</strong> [[0,0,0,0],[0,4,5,0],[0,3,1,0]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[0].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>-2<sup>31</sup> &lt;= matrix[i][j] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>A straightforward solution using <code>O(mn)</code> space is probably a bad idea.</li>
-	<li>A simple improvement uses <code>O(m + n)</code> space, but still not the best solution.</li>
-	<li>Could you devise a constant space solution?</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Game of Life](../game-of-life) (Medium)
-  1. [Number of Laser Beams in a Bank](../number-of-laser-beams-in-a-bank) (Medium)
-  1. [Minimum Operations to Remove Adjacent Ones in Matrix](../minimum-operations-to-remove-adjacent-ones-in-matrix) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If any cell of the matrix has a zero we can record its row and column number using additional memory.
-But if you don't want to use extra memory then you can manipulate the array instead. i.e. simulating exactly what the question says.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Setting cell values to zero on the fly while iterating might lead to discrepancies. What if you use some other integer value as your marker?
-There is still a better approach for this problem with 0(1) space.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We could have used 2 sets to keep a record of rows/columns which need to be set to zero. But for an O(1) space solution, you can use one of the rows and and one of the columns to keep track of this information.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-We can use the first cell of every row and column as a flag. This flag would determine whether a row or column has been set to zero.
-</details>
diff --git a/problems/set-matrix-zeroes/set_matrix_zeroes.go b/problems/set-matrix-zeroes/set_matrix_zeroes.go
deleted file mode 100644
index 3209e90d8..000000000
--- a/problems/set-matrix-zeroes/set_matrix_zeroes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem73
diff --git a/problems/set-matrix-zeroes/set_matrix_zeroes_test.go b/problems/set-matrix-zeroes/set_matrix_zeroes_test.go
deleted file mode 100644
index 3209e90d8..000000000
--- a/problems/set-matrix-zeroes/set_matrix_zeroes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem73
diff --git a/problems/set-mismatch/README.md b/problems/set-mismatch/README.md
deleted file mode 100644
index afde337fb..000000000
--- a/problems/set-mismatch/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-average-subarray-ii "Maximum Average Subarray II")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-length-of-pair-chain "Maximum Length of Pair Chain")
-
-## [645. Set Mismatch (Easy)](https://leetcode.com/problems/set-mismatch "错误的集合")
-
-<p>You have a set of integers <code>s</code>, which originally contains all the numbers from <code>1</code> to <code>n</code>. Unfortunately, due to some error, one of the numbers in <code>s</code> got duplicated to another number in the set, which results in <strong>repetition of one</strong> number and <strong>loss of another</strong> number.</p>
-
-<p>You are given an integer array <code>nums</code> representing the data status of this set after the error.</p>
-
-<p>Find the number that occurs twice and the number that is missing and return <em>them in the form of an array</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,2,4]
-<strong>Output:</strong> [2,3]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1]
-<strong>Output:</strong> [1,2]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Find the Duplicate Number](../find-the-duplicate-number) (Medium)
diff --git a/problems/set-mismatch/set_mismatch.go b/problems/set-mismatch/set_mismatch.go
deleted file mode 100644
index 65de0ac61..000000000
--- a/problems/set-mismatch/set_mismatch.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem645
diff --git a/problems/set-mismatch/set_mismatch_test.go b/problems/set-mismatch/set_mismatch_test.go
deleted file mode 100644
index 65de0ac61..000000000
--- a/problems/set-mismatch/set_mismatch_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem645
diff --git a/problems/shift-2d-grid/README.md b/problems/shift-2d-grid/README.md
deleted file mode 100644
index 3474f127a..000000000
--- a/problems/shift-2d-grid/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../handshakes-that-dont-cross "Handshakes That Don't Cross")
-　　　　　　　　　　　　　　　　
-[Next >](../find-elements-in-a-contaminated-binary-tree "Find Elements in a Contaminated Binary Tree")
-
-## [1260. Shift 2D Grid (Easy)](https://leetcode.com/problems/shift-2d-grid "二维网格迁移")
-
-<p>Given a 2D <code>grid</code> of size <code>m x n</code>&nbsp;and an integer <code>k</code>. You need to shift the <code>grid</code>&nbsp;<code>k</code> times.</p>
-
-<p>In one shift operation:</p>
-
-<ul>
-	<li>Element at <code>grid[i][j]</code> moves to <code>grid[i][j + 1]</code>.</li>
-	<li>Element at <code>grid[i][n - 1]</code> moves to <code>grid[i + 1][0]</code>.</li>
-	<li>Element at <code>grid[m&nbsp;- 1][n - 1]</code> moves to <code>grid[0][0]</code>.</li>
-</ul>
-
-<p>Return the <em>2D grid</em> after applying shift operation <code>k</code> times.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/05/e1.png" style="width: 400px; height: 178px;" />
-<pre>
-<strong>Input:</strong> <code>grid</code> = [[1,2,3],[4,5,6],[7,8,9]], k = 1
-<strong>Output:</strong> [[9,1,2],[3,4,5],[6,7,8]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/11/05/e2.png" style="width: 400px; height: 166px;" />
-<pre>
-<strong>Input:</strong> <code>grid</code> = [[3,8,1,9],[19,7,2,5],[4,6,11,10],[12,0,21,13]], k = 4
-<strong>Output:</strong> [[12,0,21,13],[3,8,1,9],[19,7,2,5],[4,6,11,10]]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> <code>grid</code> = [[1,2,3],[4,5,6],[7,8,9]], k = 9
-<strong>Output:</strong> [[1,2,3],[4,5,6],[7,8,9]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m ==&nbsp;grid.length</code></li>
-	<li><code>n ==&nbsp;grid[i].length</code></li>
-	<li><code>1 &lt;= m &lt;= 50</code></li>
-	<li><code>1 &lt;= n &lt;= 50</code></li>
-	<li><code>-1000 &lt;= grid[i][j] &lt;= 1000</code></li>
-	<li><code>0 &lt;= k &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate step by step. move grid[i][j] to grid[i][j+1]. handle last column of the grid.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Put the matrix row by row to a vector. take k % vector.length and move last k of the vector to the beginning. put the vector to the matrix back the same way.
-</details>
diff --git a/problems/shifting-letters/README.md b/problems/shifting-letters/README.md
deleted file mode 100644
index 8a9fdbb35..000000000
--- a/problems/shifting-letters/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-path-visiting-all-nodes "Shortest Path Visiting All Nodes")
-　　　　　　　　　　　　　　　　
-[Next >](../maximize-distance-to-closest-person "Maximize Distance to Closest Person")
-
-## [848. Shifting Letters (Medium)](https://leetcode.com/problems/shifting-letters "字母移位")
-
-<p>You are given a string <code>s</code> of lowercase English letters and an integer array <code>shifts</code> of the same length.</p>
-
-<p>Call the <code>shift()</code> of a letter, the next letter in the alphabet, (wrapping around so that <code>&#39;z&#39;</code> becomes <code>&#39;a&#39;</code>).</p>
-
-<ul>
-	<li>For example, <code>shift(&#39;a&#39;) = &#39;b&#39;</code>, <code>shift(&#39;t&#39;) = &#39;u&#39;</code>, and <code>shift(&#39;z&#39;) = &#39;a&#39;</code>.</li>
-</ul>
-
-<p>Now for each <code>shifts[i] = x</code>, we want to shift the first <code>i + 1</code> letters of <code>s</code>, <code>x</code> times.</p>
-
-<p>Return <em>the final string after all such shifts to s are applied</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;, shifts = [3,5,9]
-<strong>Output:</strong> &quot;rpl&quot;
-<strong>Explanation:</strong> We start with &quot;abc&quot;.
-After shifting the first 1 letters of s by 3, we have &quot;dbc&quot;.
-After shifting the first 2 letters of s by 5, we have &quot;igc&quot;.
-After shifting the first 3 letters of s by 9, we have &quot;rpl&quot;, the answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaa&quot;, shifts = [1,2,3]
-<strong>Output:</strong> &quot;gfd&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-	<li><code>shifts.length == s.length</code></li>
-	<li><code>0 &lt;= shifts[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/shifting-letters/shifting_letters.go b/problems/shifting-letters/shifting_letters.go
deleted file mode 100644
index 89808b3f7..000000000
--- a/problems/shifting-letters/shifting_letters.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem848
diff --git a/problems/shifting-letters/shifting_letters_test.go b/problems/shifting-letters/shifting_letters_test.go
deleted file mode 100644
index 89808b3f7..000000000
--- a/problems/shifting-letters/shifting_letters_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem848
diff --git a/problems/shopping-offers/README.md b/problems/shopping-offers/README.md
deleted file mode 100644
index 7203395b5..000000000
--- a/problems/shopping-offers/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../average-of-levels-in-binary-tree "Average of Levels in Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../decode-ways-ii "Decode Ways II")
-
-## [638. Shopping Offers (Medium)](https://leetcode.com/problems/shopping-offers "大礼包")
-
-<p>In LeetCode Store, there are <code>n</code> items to sell. Each item has a price. However, there are some special offers, and a special offer consists of one or more different kinds of items with a sale price.</p>
-
-<p>You are given an integer array <code>price</code> where <code>price[i]</code> is the price of the <code>i<sup>th</sup></code> item, and an integer array <code>needs</code> where <code>needs[i]</code> is the number of pieces of the <code>i<sup>th</sup></code> item you want to buy.</p>
-
-<p>You are also given an array <code>special</code> where <code>special[i]</code> is of size <code>n + 1</code> where <code>special[i][j]</code> is the number of pieces of the <code>j<sup>th</sup></code> item in the <code>i<sup>th</sup></code> offer and <code>special[i][n]</code> (i.e., the last integer in the array) is the price of the <code>i<sup>th</sup></code> offer.</p>
-
-<p>Return <em>the lowest price you have to pay for exactly certain items as given, where you could make optimal use of the special offers</em>. You are not allowed to buy more items than you want, even if that would lower the overall price. You could use any of the special offers as many times as you want.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> price = [2,5], special = [[3,0,5],[1,2,10]], needs = [3,2]
-<strong>Output:</strong> 14
-<strong>Explanation:</strong> There are two kinds of items, A and B. Their prices are $2 and $5 respectively. 
-In special offer 1, you can pay $5 for 3A and 0B
-In special offer 2, you can pay $10 for 1A and 2B. 
-You need to buy 3A and 2B, so you may pay $10 for 1A and 2B (special offer #2), and $4 for 2A.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> price = [2,3,4], special = [[1,1,0,4],[2,2,1,9]], needs = [1,2,1]
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> The price of A is $2, and $3 for B, $4 for C. 
-You may pay $4 for 1A and 1B, and $9 for 2A ,2B and 1C. 
-You need to buy 1A ,2B and 1C, so you may pay $4 for 1A and 1B (special offer #1), and $3 for 1B, $4 for 1C. 
-You cannot add more items, though only $9 for 2A ,2B and 1C.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == price.length</code></li>
-	<li><code>n == needs.length</code></li>
-	<li><code>1 &lt;= n &lt;= 6</code></li>
-	<li><code>0 &lt;= price[i] &lt;= 10</code></li>
-	<li><code>0 &lt;= needs[i] &lt;= 10</code></li>
-	<li><code>1 &lt;= special.length &lt;= 100</code></li>
-	<li><code>special[i].length == n + 1</code></li>
-	<li><code>0 &lt;= special[i][j] &lt;= 50</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
diff --git a/problems/shopping-offers/shopping_offers.go b/problems/shopping-offers/shopping_offers.go
deleted file mode 100644
index d5d53a76e..000000000
--- a/problems/shopping-offers/shopping_offers.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem638
diff --git a/problems/shopping-offers/shopping_offers_test.go b/problems/shopping-offers/shopping_offers_test.go
deleted file mode 100644
index d5d53a76e..000000000
--- a/problems/shopping-offers/shopping_offers_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem638
diff --git a/problems/short-encoding-of-words/README.md b/problems/short-encoding-of-words/README.md
deleted file mode 100644
index 96b3b8a2a..000000000
--- a/problems/short-encoding-of-words/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../most-common-word "Most Common Word")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-distance-to-a-character "Shortest Distance to a Character")
-
-## [820. Short Encoding of Words (Medium)](https://leetcode.com/problems/short-encoding-of-words "单词的压缩编码")
-
-<p>A <strong>valid encoding</strong> of an array of <code>words</code> is any reference string <code>s</code> and array of indices <code>indices</code> such that:</p>
-
-<ul>
-	<li><code>words.length == indices.length</code></li>
-	<li>The reference string <code>s</code> ends with the <code>&#39;#&#39;</code> character.</li>
-	<li>For each index <code>indices[i]</code>, the <strong>substring</strong> of <code>s</code> starting from <code>indices[i]</code> and up to (but not including) the next <code>&#39;#&#39;</code> character is equal to <code>words[i]</code>.</li>
-</ul>
-
-<p>Given an array of <code>words</code>, return <em>the <strong>length of the shortest reference string</strong> </em><code>s</code><em> possible of any <strong>valid encoding</strong> of </em><code>words</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;time&quot;, &quot;me&quot;, &quot;bell&quot;]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> A valid encoding would be s = <code>&quot;time#bell#&quot; and indices = [0, 2, 5</code>].
-words[0] = &quot;time&quot;, the substring of s starting from indices[0] = 0 to the next &#39;#&#39; is underlined in &quot;<u>time</u>#bell#&quot;
-words[1] = &quot;me&quot;, the substring of s starting from indices[1] = 2 to the next &#39;#&#39; is underlined in &quot;ti<u>me</u>#bell#&quot;
-words[2] = &quot;bell&quot;, the substring of s starting from indices[2] = 5 to the next &#39;#&#39; is underlined in &quot;time#<u>bell</u>#&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;t&quot;]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> A valid encoding would be s = &quot;t#&quot; and indices = [0].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 2000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 7</code></li>
-	<li><code>words[i]</code> consists of only lowercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Trie](../../tag/trie/README.md)]
diff --git a/problems/short-encoding-of-words/short_encoding_of_words.go b/problems/short-encoding-of-words/short_encoding_of_words.go
deleted file mode 100644
index 9ac2d4147..000000000
--- a/problems/short-encoding-of-words/short_encoding_of_words.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem820
diff --git a/problems/short-encoding-of-words/short_encoding_of_words_test.go b/problems/short-encoding-of-words/short_encoding_of_words_test.go
deleted file mode 100644
index 9ac2d4147..000000000
--- a/problems/short-encoding-of-words/short_encoding_of_words_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem820
diff --git a/problems/shortest-bridge/README.md b/problems/shortest-bridge/README.md
deleted file mode 100644
index c28bec2ab..000000000
--- a/problems/shortest-bridge/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-recent-calls "Number of Recent Calls")
-　　　　　　　　　　　　　　　　
-[Next >](../knight-dialer "Knight Dialer")
-
-## [934. Shortest Bridge (Medium)](https://leetcode.com/problems/shortest-bridge "最短的桥")
-
-<p>You are given an <code>n x n</code> binary matrix <code>grid</code> where <code>1</code> represents land and <code>0</code> represents water.</p>
-
-<p>An <strong>island</strong> is a 4-directionally connected group of <code>1</code>&#39;s not connected to any other <code>1</code>&#39;s. There are <strong>exactly two islands</strong> in <code>grid</code>.</p>
-
-<p>You may change <code>0</code>&#39;s to <code>1</code>&#39;s to connect the two islands to form <strong>one island</strong>.</p>
-
-<p>Return <em>the smallest number of </em><code>0</code><em>&#39;s you must flip to connect the two islands</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0,1],[1,0]]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[0,1,0],[0,0,0],[0,0,1]]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,1,1,1],[1,0,0,0,1],[1,0,1,0,1],[1,0,0,0,1],[1,1,1,1,1]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length == grid[i].length</code></li>
-	<li><code>2 &lt;= n &lt;= 100</code></li>
-	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-	<li>There are exactly two islands in <code>grid</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/shortest-bridge/shortest_bridge.go b/problems/shortest-bridge/shortest_bridge.go
deleted file mode 100644
index 75dd21f2c..000000000
--- a/problems/shortest-bridge/shortest_bridge.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem934
diff --git a/problems/shortest-bridge/shortest_bridge_test.go b/problems/shortest-bridge/shortest_bridge_test.go
deleted file mode 100644
index 75dd21f2c..000000000
--- a/problems/shortest-bridge/shortest_bridge_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem934
diff --git a/problems/shortest-common-supersequence/README.md b/problems/shortest-common-supersequence/README.md
deleted file mode 100644
index 1a5ac13e8..000000000
--- a/problems/shortest-common-supersequence/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-path-in-binary-matrix "Shortest Path in Binary Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../statistics-from-a-large-sample "Statistics from a Large Sample")
-
-## [1092. Shortest Common Supersequence  (Hard)](https://leetcode.com/problems/shortest-common-supersequence "最短公共超序列")
-
-<p>Given two strings <code>str1</code> and <code>str2</code>, return <em>the shortest string that has both </em><code>str1</code><em> and </em><code>str2</code><em> as <strong>subsequences</strong></em>. If there are multiple valid strings, return <strong>any</strong> of them.</p>
-
-<p>A string <code>s</code> is a <strong>subsequence</strong> of string <code>t</code> if deleting some number of characters from <code>t</code> (possibly <code>0</code>) results in the string <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> str1 = &quot;abac&quot;, str2 = &quot;cab&quot;
-<strong>Output:</strong> &quot;cabac&quot;
-<strong>Explanation:</strong> 
-str1 = &quot;abac&quot; is a subsequence of &quot;cabac&quot; because we can delete the first &quot;c&quot;.
-str2 = &quot;cab&quot; is a subsequence of &quot;cabac&quot; because we can delete the last &quot;ac&quot;.
-The answer provided is the shortest such string that satisfies these properties.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> str1 = &quot;aaaaaaaa&quot;, str2 = &quot;aaaaaaaa&quot;
-<strong>Output:</strong> &quot;aaaaaaaa&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= str1.length, str2.length &lt;= 1000</code></li>
-	<li><code>str1</code> and <code>str2</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can find the length of the longest common subsequence between str1[i:] and str2[j:] (for all (i, j)) by using dynamic programming.  We can use this information to recover the longest common supersequence.
-</details>
diff --git a/problems/shortest-common-supersequence/shortest_common_supersequence.go b/problems/shortest-common-supersequence/shortest_common_supersequence.go
deleted file mode 100644
index 86c6404f4..000000000
--- a/problems/shortest-common-supersequence/shortest_common_supersequence.go
+++ /dev/null
@@ -1,64 +0,0 @@
-package problem1092
-
-import "strings"
-
-func shortestCommonSupersequence(A, B string) string {
-	m, n := len(A), len(B)
-	// 解题思路，
-	//   先求出 A 和 B 的 LCS，
-	//   然后，在 LCS 上添加缺少的字母
-	// 利用 dp 求解 LCS ,
-	// dp[i][j]=k 表示 A[:i] 与 B[:j] 的 LCS 的长度为 k
-	// 在递归过程中，会出现三种情况:
-	//   1. A[i]=B[j]， 则 dp[i][j]= dp[i-1][j-1]+1
-	//   2. A[i]!=B[j] 且 dp[i-1][j] >= dp[i][j-1]，则 dp[i][j]=dp[i-1][j]
-	//   3. A[i]!=B[j] 且 dp[i-1][j] < dp[i][j-1]，则 dp[i][j]=dp[i][j+1]
-
-	dp := [1001][1001]int{}
-	b := [1001][1001]int{} // 记录哪种情况发生了，以便添加字母
-
-	for i := 1; i <= m; i++ {
-		for j := 1; j <= n; j++ {
-			if A[i-1] == B[j-1] {
-				dp[i][j] = dp[i-1][j-1] + 1
-				b[i][j] = 1
-			} else if dp[i-1][j] >= dp[i][j-1] {
-				dp[i][j] = dp[i-1][j]
-				b[i][j] = 2
-			} else {
-				dp[i][j] = dp[i][j-1]
-				b[i][j] = 3
-			}
-		}
-	}
-
-	var sb strings.Builder
-	var dfs func(int, int)
-	dfs = func(i, j int) {
-		if i == 0 {
-			sb.WriteString(B[:j])
-			return
-		}
-
-		if j == 0 {
-			sb.WriteString(A[:i])
-			return
-		}
-
-		switch b[i][j] {
-		case 1:
-			dfs(i-1, j-1)
-			sb.WriteByte(A[i-1])
-		case 2:
-			dfs(i-1, j)
-			sb.WriteByte(A[i-1])
-		case 3:
-			dfs(i, j-1)
-			sb.WriteByte(B[j-1])
-		}
-	}
-
-	dfs(m, n)
-
-	return sb.String()
-}
diff --git a/problems/shortest-completing-word/README.md b/problems/shortest-completing-word/README.md
deleted file mode 100644
index 10eb3e10f..000000000
--- a/problems/shortest-completing-word/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-number-at-least-twice-of-others "Largest Number At Least Twice of Others")
-　　　　　　　　　　　　　　　　
-[Next >](../contain-virus "Contain Virus")
-
-## [748. Shortest Completing Word (Easy)](https://leetcode.com/problems/shortest-completing-word "最短补全词")
-
-<p>Given a string <code>licensePlate</code> and an array of strings <code>words</code>, find the <strong>shortest completing</strong> word in <code>words</code>.</p>
-
-<p>A <strong>completing</strong> word is a word that <strong>contains all the letters</strong> in <code>licensePlate</code>. <strong>Ignore numbers and spaces</strong> in <code>licensePlate</code>, and treat letters as <strong>case insensitive</strong>. If a letter appears more than once in <code>licensePlate</code>, then it must appear in the word the same number of times or more.</p>
-
-<p>For example, if <code>licensePlate</code><code> = &quot;aBc 12c&quot;</code>, then it contains letters <code>&#39;a&#39;</code>, <code>&#39;b&#39;</code> (ignoring case), and <code>&#39;c&#39;</code> twice. Possible <strong>completing</strong> words are <code>&quot;abccdef&quot;</code>, <code>&quot;caaacab&quot;</code>, and <code>&quot;cbca&quot;</code>.</p>
-
-<p>Return <em>the shortest <strong>completing</strong> word in </em><code>words</code><em>.</em> It is guaranteed an answer exists. If there are multiple shortest <strong>completing</strong> words, return the <strong>first</strong> one that occurs in <code>words</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> licensePlate = &quot;1s3 PSt&quot;, words = [&quot;step&quot;,&quot;steps&quot;,&quot;stripe&quot;,&quot;stepple&quot;]
-<strong>Output:</strong> &quot;steps&quot;
-<strong>Explanation:</strong> licensePlate contains letters &#39;s&#39;, &#39;p&#39;, &#39;s&#39; (ignoring case), and &#39;t&#39;.
-&quot;step&quot; contains &#39;t&#39; and &#39;p&#39;, but only contains 1 &#39;s&#39;.
-&quot;steps&quot; contains &#39;t&#39;, &#39;p&#39;, and both &#39;s&#39; characters.
-&quot;stripe&quot; is missing an &#39;s&#39;.
-&quot;stepple&quot; is missing an &#39;s&#39;.
-Since &quot;steps&quot; is the only word containing all the letters, that is the answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> licensePlate = &quot;1s3 456&quot;, words = [&quot;looks&quot;,&quot;pest&quot;,&quot;stew&quot;,&quot;show&quot;]
-<strong>Output:</strong> &quot;pest&quot;
-<strong>Explanation:</strong> licensePlate only contains the letter &#39;s&#39;. All the words contain &#39;s&#39;, but among these &quot;pest&quot;, &quot;stew&quot;, and &quot;show&quot; are shortest. The answer is &quot;pest&quot; because it is the word that appears earliest of the 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= licensePlate.length &lt;= 7</code></li>
-	<li><code>licensePlate</code> contains digits, letters (uppercase or lowercase), or space <code>&#39; &#39;</code>.</li>
-	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 15</code></li>
-	<li><code>words[i]</code> consists of lower case English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count only the letters (possibly converted to lowercase) of each word.  If a word is shorter and the count of each letter is at least the count of that letter in the licensePlate, it is the best answer we've seen yet.
-</details>
diff --git a/problems/shortest-completing-word/shortest_completing_word.go b/problems/shortest-completing-word/shortest_completing_word.go
deleted file mode 100644
index aad7f10d2..000000000
--- a/problems/shortest-completing-word/shortest_completing_word.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem748
diff --git a/problems/shortest-completing-word/shortest_completing_word_test.go b/problems/shortest-completing-word/shortest_completing_word_test.go
deleted file mode 100644
index aad7f10d2..000000000
--- a/problems/shortest-completing-word/shortest_completing_word_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem748
diff --git a/problems/shortest-distance-from-all-buildings/README.md b/problems/shortest-distance-from-all-buildings/README.md
deleted file mode 100644
index d8508700c..000000000
--- a/problems/shortest-distance-from-all-buildings/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-duplicate-letters "Remove Duplicate Letters")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-product-of-word-lengths "Maximum Product of Word Lengths")
-
-## [317. Shortest Distance from All Buildings (Hard)](https://leetcode.com/problems/shortest-distance-from-all-buildings "离建筑物最近的距离")
-
-<p>You want to build a house on an <i>empty</i> land which reaches all buildings in the shortest amount of distance. You can only move up, down, left and right. You are given a 2D grid of values <b>0</b>, <b>1</b> or <b>2</b>, where:</p>
-
-<ul>
-	<li>Each <b>0</b> marks an empty land which you can pass by freely.</li>
-	<li>Each <b>1</b> marks a building which you cannot pass through.</li>
-	<li>Each <b>2</b> marks an obstacle which you cannot pass through.</li>
-</ul>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong> [[1,0,2,0,1],[0,0,0,0,0],[0,0,1,0,0]]
-
-1 - 0 - 2 - 0 - 1
-|   |   |   |   |
-0 - 0 - 0 - 0 - 0
-|   |   |   |   |
-0 - 0 - 1 - 0 - 0
-
-<strong>Output:</strong> 7 
-
-<strong>Explanation:</strong> Given three buildings at <code>(0,0)</code>, <code>(0,4)</code>, <code>(2,2)</code>, and an obstacle at <code>(0,2),
-             t</code>he point <code>(1,2)</code> is an ideal empty land to build a house, as the total 
-&nbsp;            travel distance of 3+3+1=7 is minimal. So return 7.</pre>
-
-<p><b>Note:</b><br />
-There will be at least one building. If it is not possible to build such house according to the above rules, return -1.</p>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Walls and Gates](../walls-and-gates) (Medium)
-  1. [Best Meeting Point](../best-meeting-point) (Hard)
-  1. [As Far from Land as Possible](../as-far-from-land-as-possible) (Medium)
diff --git a/problems/shortest-distance-from-all-buildings/shortest_distance_from_all_buildings.go b/problems/shortest-distance-from-all-buildings/shortest_distance_from_all_buildings.go
deleted file mode 100644
index 5b74b6b4a..000000000
--- a/problems/shortest-distance-from-all-buildings/shortest_distance_from_all_buildings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem317
diff --git a/problems/shortest-distance-from-all-buildings/shortest_distance_from_all_buildings_test.go b/problems/shortest-distance-from-all-buildings/shortest_distance_from_all_buildings_test.go
deleted file mode 100644
index 5b74b6b4a..000000000
--- a/problems/shortest-distance-from-all-buildings/shortest_distance_from_all_buildings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem317
diff --git a/problems/shortest-distance-in-a-line/README.md b/problems/shortest-distance-in-a-line/README.md
deleted file mode 100644
index 1d788e5d0..000000000
--- a/problems/shortest-distance-in-a-line/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-distance-in-a-plane "Shortest Distance in a Plane")
-　　　　　　　　　　　　　　　　
-[Next >](../second-degree-follower "Second Degree Follower")
-
-## [613. Shortest Distance in a Line (Easy)](https://leetcode.com/problems/shortest-distance-in-a-line "直线上的最近距离")
-
-Table <code>point</code> holds the x coordinate of some points on x-axis in a plane, which are all integers.
-<p>&nbsp;</p>
-Write a query to find the shortest distance between two points in these points.
-
-<p>&nbsp;</p>
-
-<pre>
-| x   |
-|-----|
-| -1  |
-| 0   |
-| 2   |
-</pre>
-
-<p>&nbsp;</p>
-The shortest distance is &#39;1&#39; obviously, which is from point &#39;-1&#39; to &#39;0&#39;. So the output is as below:
-
-<p>&nbsp;</p>
-
-<pre>
-| shortest|
-|---------|
-| 1       |
-</pre>
-
-<p>&nbsp;</p>
-<b>Note:</b> Every point is unique, which means there is no duplicates in table <code>point</code>.
-
-<p>&nbsp;</p>
-<b>Follow-up:</b> What if all these points have an id and are arranged from the left most to the right most of x axis?
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/shortest-distance-in-a-line/mysql_schemas.sql b/problems/shortest-distance-in-a-line/mysql_schemas.sql
deleted file mode 100644
index bef5a5599..000000000
--- a/problems/shortest-distance-in-a-line/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create Table If Not Exists Point (x int not null);
-Truncate table Point;
-insert into Point (x) values ('-1');
-insert into Point (x) values ('0');
-insert into Point (x) values ('2');
diff --git a/problems/shortest-distance-in-a-line/shortest_distance_in_a_line.sql b/problems/shortest-distance-in-a-line/shortest_distance_in_a_line.sql
deleted file mode 100644
index 335040c49..000000000
--- a/problems/shortest-distance-in-a-line/shortest_distance_in_a_line.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT MIN(ABS(p1.x - p2.x)) AS shortest
-FROM
-  point p1
-  JOIN
-  point p2 ON p1.x != p2.x;
diff --git a/problems/shortest-distance-in-a-plane/README.md b/problems/shortest-distance-in-a-plane/README.md
deleted file mode 100644
index 3f758e57e..000000000
--- a/problems/shortest-distance-in-a-plane/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-triangle-number "Valid Triangle Number")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-distance-in-a-line "Shortest Distance in a Line")
-
-## [612. Shortest Distance in a Plane (Medium)](https://leetcode.com/problems/shortest-distance-in-a-plane "平面上的最近距离")
-
-Table <code>point_2d</code> holds the coordinates (x,y) of some unique points (more than two) in a plane.
-<p>&nbsp;</p>
-Write a query to find the shortest distance between these points rounded to 2 decimals.
-
-<p>&nbsp;</p>
-
-<pre>
-| x  | y  |
-|----|----|
-| -1 | -1 |
-| 0  | 0  |
-| -1 | -2 |
-</pre>
-
-<p>&nbsp;</p>
-The shortest distance is 1.00 from point (-1,-1) to (-1,2). So the output should be:
-
-<p>&nbsp;</p>
-
-<pre>
-| shortest |
-|----------|
-| 1.00     |
-</pre>
-
-<p>&nbsp;</p>
-<b>Note:</b> The longest distance among all the points are less than 10000.
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/shortest-distance-in-a-plane/mysql_schemas.sql b/problems/shortest-distance-in-a-plane/mysql_schemas.sql
deleted file mode 100644
index fe36290c3..000000000
--- a/problems/shortest-distance-in-a-plane/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create Table If Not Exists Point2D (x int not null, y int not null);
-Truncate table Point2D;
-insert into Point2D (x, y) values ('-1', '-1');
-insert into Point2D (x, y) values ('0', '0');
-insert into Point2D (x, y) values ('-1', '-2');
diff --git a/problems/shortest-distance-in-a-plane/shortest_distance_in_a_plane.sql b/problems/shortest-distance-in-a-plane/shortest_distance_in_a_plane.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/shortest-distance-in-a-plane/shortest_distance_in_a_plane.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/shortest-distance-to-a-character/README.md b/problems/shortest-distance-to-a-character/README.md
deleted file mode 100644
index 1ae107496..000000000
--- a/problems/shortest-distance-to-a-character/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../short-encoding-of-words "Short Encoding of Words")
-　　　　　　　　　　　　　　　　
-[Next >](../card-flipping-game "Card Flipping Game")
-
-## [821. Shortest Distance to a Character (Easy)](https://leetcode.com/problems/shortest-distance-to-a-character "字符的最短距离")
-
-<p>Given a string <code>s</code> and a character <code>c</code> that occurs in <code>s</code>, return <em>an array of integers </em><code>answer</code><em> where </em><code>answer.length == s.length</code><em> and </em><code>answer[i]</code><em> is the <strong>distance</strong> from index </em><code>i</code><em> to the <strong>closest</strong> occurrence of character </em><code>c</code><em> in </em><code>s</code>.</p>
-
-<p>The <strong>distance</strong> between two indices <code>i</code> and <code>j</code> is <code>abs(i - j)</code>, where <code>abs</code> is the absolute value function.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;loveleetcode&quot;, c = &quot;e&quot;
-<strong>Output:</strong> [3,2,1,0,1,0,0,1,2,2,1,0]
-<strong>Explanation:</strong> The character &#39;e&#39; appears at indices 3, 5, 6, and 11 (0-indexed).
-The closest occurrence of &#39;e&#39; for index 0 is at index 3, so the distance is abs(0 - 3) = 3.
-The closest occurrence of &#39;e&#39; for index 1 is at index 3, so the distance is abs(1 - 3) = 2.
-For index 4, there is a tie between the &#39;e&#39; at index 3 and the &#39;e&#39; at index 5, but the distance is still the same: abs(4 - 3) == abs(4 - 5) = 1.
-The closest occurrence of &#39;e&#39; for index 8 is at index 6, so the distance is abs(8 - 6) = 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaab&quot;, c = &quot;b&quot;
-<strong>Output:</strong> [3,2,1,0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s[i]</code> and <code>c</code> are lowercase English letters.</li>
-	<li>It is guaranteed that <code>c</code> occurs at least once in <code>s</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/shortest-distance-to-a-character/shortest_distance_to_a_character.go b/problems/shortest-distance-to-a-character/shortest_distance_to_a_character.go
deleted file mode 100644
index f3928e550..000000000
--- a/problems/shortest-distance-to-a-character/shortest_distance_to_a_character.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem821
diff --git a/problems/shortest-distance-to-a-character/shortest_distance_to_a_character_test.go b/problems/shortest-distance-to-a-character/shortest_distance_to_a_character_test.go
deleted file mode 100644
index f3928e550..000000000
--- a/problems/shortest-distance-to-a-character/shortest_distance_to_a_character_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem821
diff --git a/problems/shortest-distance-to-target-color/README.md b/problems/shortest-distance-to-target-color/README.md
deleted file mode 100644
index e5974c4fa..000000000
--- a/problems/shortest-distance-to-target-color/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../before-and-after-puzzle "Before and After Puzzle")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-ones "Maximum Number of Ones")
-
-## [1182. Shortest Distance to Target Color (Medium)](https://leetcode.com/problems/shortest-distance-to-target-color "与目标颜色间的最短距离")
-
-<p>You are given an array <code>colors</code>, in which there are three colors: <code>1</code>, <code>2</code> and&nbsp;<code>3</code>.</p>
-
-<p>You are also given some queries. Each query consists of two integers <code>i</code>&nbsp;and <code>c</code>, return&nbsp;the shortest distance between the given index&nbsp;<code>i</code> and the target color <code>c</code>. If there is no solution return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> colors = [1,1,2,1,3,2,2,3,3], queries = [[1,3],[2,2],[6,1]]
-<strong>Output:</strong> [3,0,3]
-<strong>Explanation: </strong>
-The nearest 3 from index 1 is at index 4 (3 steps away).
-The nearest 2 from index 2 is at index 2 itself (0 steps away).
-The nearest 1 from index 6 is at index 3 (3 steps away).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> colors = [1,2], queries = [[0,3]]
-<strong>Output:</strong> [-1]
-<strong>Explanation: </strong>There is no 3 in the array.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= colors.length &lt;= 5*10^4</code></li>
-	<li><code>1 &lt;= colors[i] &lt;= 3</code></li>
-	<li><code>1&nbsp;&lt;= queries.length &lt;= 5*10^4</code></li>
-	<li><code>queries[i].length == 2</code></li>
-	<li><code>0 &lt;= queries[i][0] &lt;&nbsp;colors.length</code></li>
-	<li><code>1 &lt;= queries[i][1] &lt;= 3</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Greedy solution is too slow because of the limits.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can you solve this problem offline by doing some pre-processing?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Calculate the answers for all indexes moving to their left and to their right.
-</details>
diff --git a/problems/shortest-palindrome/README.md b/problems/shortest-palindrome/README.md
deleted file mode 100644
index 28f4df0e1..000000000
--- a/problems/shortest-palindrome/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../house-robber-ii "House Robber II")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-largest-element-in-an-array "Kth Largest Element in an Array")
-
-## [214. Shortest Palindrome (Hard)](https://leetcode.com/problems/shortest-palindrome "最短回文串")
-
-<p>You are given a string <code>s</code>. You can convert <code>s</code> to a palindrome by adding characters in front of it.</p>
-
-<p>Return <em>the shortest palindrome you can find by performing this transformation</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "aacecaaa"
-<strong>Output:</strong> "aaacecaaa"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "abcd"
-<strong>Output:</strong> "dcbabcd"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters only.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-
-### Similar Questions
-  1. [Longest Palindromic Substring](../longest-palindromic-substring) (Medium)
-  1. [Implement strStr()](../implement-strstr) (Easy)
-  1. [Palindrome Pairs](../palindrome-pairs) (Hard)
diff --git a/problems/shortest-palindrome/shortest_palindrome.go b/problems/shortest-palindrome/shortest_palindrome.go
deleted file mode 100644
index 54b8dbd28..000000000
--- a/problems/shortest-palindrome/shortest_palindrome.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem214
diff --git a/problems/shortest-palindrome/shortest_palindrome_test.go b/problems/shortest-palindrome/shortest_palindrome_test.go
deleted file mode 100644
index 54b8dbd28..000000000
--- a/problems/shortest-palindrome/shortest_palindrome_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem214
diff --git a/problems/shortest-path-in-a-grid-with-obstacles-elimination/README.md b/problems/shortest-path-in-a-grid-with-obstacles-elimination/README.md
deleted file mode 100644
index 50024922b..000000000
--- a/problems/shortest-path-in-a-grid-with-obstacles-elimination/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold "Maximum Side Length of a Square with Sum Less than or Equal to Threshold")
-　　　　　　　　　　　　　　　　
-[Next >](../weather-type-in-each-country "Weather Type in Each Country")
-
-## [1293. Shortest Path in a Grid with Obstacles Elimination (Hard)](https://leetcode.com/problems/shortest-path-in-a-grid-with-obstacles-elimination "网格中的最短路径")
-
-<p>You are given an <code>m x n</code> integer matrix <code>grid</code> where each cell is either <code>0</code> (empty) or <code>1</code> (obstacle). You can move up, down, left, or right from and to an empty cell in <strong>one step</strong>.</p>
-
-<p>Return <em>the minimum number of <strong>steps</strong> to walk from the upper left corner </em><code>(0, 0)</code><em> to the lower right corner </em><code>(m - 1, n - 1)</code><em> given that you can eliminate <strong>at most</strong> </em><code>k</code><em> obstacles</em>. If it is not possible to find such walk return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/30/short1-grid.jpg" style="width: 244px; height: 405px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,0,0],[1,1,0],[0,0,0],[0,1,1],[0,0,0]], k = 1
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> 
-The shortest path without eliminating any obstacle is 10.
-The shortest path with one obstacle elimination at position (3,2) is 6. Such path is (0,0) -&gt; (0,1) -&gt; (0,2) -&gt; (1,2) -&gt; (2,2) -&gt; <strong>(3,2)</strong> -&gt; (4,2).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/30/short2-grid.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1,1],[1,1,1],[1,0,0]], k = 1
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> We need to eliminate at least two obstacles to find such a walk.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 40</code></li>
-	<li><code>1 &lt;= k &lt;= m * n</code></li>
-	<li><code>grid[i][j]</code> is either <code>0</code> <strong>or</strong> <code>1</code>.</li>
-	<li><code>grid[0][0] == grid[m - 1][n - 1] == 0</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Shortest Path to Get Food](../shortest-path-to-get-food) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use BFS.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-BFS on (x,y,r) x,y is coordinate, r is remain number of obstacles you can remove.
-</details>
diff --git a/problems/shortest-path-in-a-hidden-grid/README.md b/problems/shortest-path-in-a-hidden-grid/README.md
deleted file mode 100644
index c519f5a97..000000000
--- a/problems/shortest-path-in-a-hidden-grid/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../products-price-for-each-store "Product's Price for Each Store")
-　　　　　　　　　　　　　　　　
-[Next >](../find-nearest-point-that-has-the-same-x-or-y-coordinate "Find Nearest Point That Has the Same X or Y Coordinate")
-
-## [1778. Shortest Path in a Hidden Grid (Medium)](https://leetcode.com/problems/shortest-path-in-a-hidden-grid "未知网格中的最短路径")
-
-
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Similar Questions
-  1. [Robot Room Cleaner](../robot-room-cleaner) (Hard)
-  1. [Minimum Path Cost in a Hidden Grid](../minimum-path-cost-in-a-hidden-grid) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The grid is at a maximum 500 x 500, so it is clever to assume that the robot's initial cell is grid[501][501]
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Run a DFS from the robot's position to make sure that you can reach the target, otherwise you should return -1.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Now that you are sure you can reach the target, run BFS to find the shortest path.
-</details>
diff --git a/problems/shortest-path-in-binary-matrix/README.md b/problems/shortest-path-in-binary-matrix/README.md
deleted file mode 100644
index 2922b9f93..000000000
--- a/problems/shortest-path-in-binary-matrix/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-values-from-labels "Largest Values From Labels")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-common-supersequence "Shortest Common Supersequence ")
-
-## [1091. Shortest Path in Binary Matrix (Medium)](https://leetcode.com/problems/shortest-path-in-binary-matrix "二进制矩阵中的最短路径")
-
-<p>Given an <code>n x n</code> binary matrix <code>grid</code>, return <em>the length of the shortest <strong>clear path</strong> in the matrix</em>. If there is no clear path, return <code>-1</code>.</p>
-
-<p>A <strong>clear path</strong> in a binary matrix is a path from the <strong>top-left</strong> cell (i.e., <code>(0, 0)</code>) to the <strong>bottom-right</strong> cell (i.e., <code>(n - 1, n - 1)</code>) such that:</p>
-
-<ul>
-	<li>All the visited cells of the path are <code>0</code>.</li>
-	<li>All the adjacent cells of the path are <strong>8-directionally</strong> connected (i.e., they are different and they share an edge or a corner).</li>
-</ul>
-
-<p>The <strong>length of a clear path</strong> is the number of visited cells of this path.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/example1_1.png" style="width: 500px; height: 234px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1],[1,0]]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/example2_1.png" style="height: 216px; width: 500px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,0,0],[1,1,0],[1,1,0]]
-<strong>Output:</strong> 4
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,0,0],[1,1,0],[1,1,0]]
-<strong>Output:</strong> -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>grid[i][j] is 0 or 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do a breadth first search to find the shortest path.
-</details>
diff --git a/problems/shortest-path-in-binary-matrix/shortest_path_in_binary_matrix.go b/problems/shortest-path-in-binary-matrix/shortest_path_in_binary_matrix.go
deleted file mode 100644
index d74666772..000000000
--- a/problems/shortest-path-in-binary-matrix/shortest_path_in_binary_matrix.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package problem1091
-
-var dx = []int{-1, -1, -1, 0, 1, 1, 1, 0}
-var dy = []int{-1, 0, 1, 1, 1, 0, -1, -1}
-
-func shortestPathBinaryMatrix(grid [][]int) int {
-	if grid[0][0] == 1 {
-		return -1
-	}
-
-	N := len(grid)
-
-	cells := make([][2]int, 1, N*N)
-	grid[0][0] = 1
-	length := 1
-
-	for len(cells) > 0 {
-		size := len(cells)
-		for s := 0; s < size; s++ {
-			c := cells[s]
-			x, y := c[0], c[1]
-			if x == N-1 && y == N-1 {
-				return length
-			}
-			for k := 0; k < 8; k++ {
-				i, j := x+dx[k], y+dy[k]
-				if i < 0 || N <= i ||
-					j < 0 || N <= j ||
-					grid[i][j] == 1 {
-					continue
-				}
-				cells = append(cells, [2]int{i, j})
-				grid[i][j] = 1
-			}
-		}
-		length++
-		cells = cells[size:]
-	}
-
-	return -1
-}
diff --git a/problems/shortest-path-to-get-all-keys/README.md b/problems/shortest-path-to-get-all-keys/README.md
deleted file mode 100644
index 8499f1d63..000000000
--- a/problems/shortest-path-to-get-all-keys/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-nodes-distance-k-in-binary-tree "All Nodes Distance K in Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-subtree-with-all-the-deepest-nodes "Smallest Subtree with all the Deepest Nodes")
-
-## [864. Shortest Path to Get All Keys (Hard)](https://leetcode.com/problems/shortest-path-to-get-all-keys "获取所有钥匙的最短路径")
-
-<p>You are given an <code>m x n</code> grid <code>grid</code> where:</p>
-
-<ul>
-	<li><code>&#39;.&#39;</code> is an empty cell.</li>
-	<li><code>&#39;#&#39;</code> is a wall.</li>
-	<li><code>&#39;@&#39;</code> is the starting point.</li>
-	<li>Lowercase letters represent keys.</li>
-	<li>Uppercase letters represent locks.</li>
-</ul>
-
-<p>You start at the starting point and one move consists of walking one space in one of the four cardinal directions. You cannot walk outside the grid, or walk into a wall.</p>
-
-<p>If you walk over a key, you can pick it up and you cannot walk over a lock unless you have its corresponding key.</p>
-
-<p>For some <code><font face="monospace">1 &lt;= k &lt;= 6</font></code>, there is exactly one lowercase and one uppercase letter of the first <code>k</code> letters of the English alphabet in the grid. This means that there is exactly one key for each lock, and one lock for each key; and also that the letters used to represent the keys and locks were chosen in the same order as the English alphabet.</p>
-
-<p>Return <em>the lowest number of moves to acquire all keys</em>. If it is impossible, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-keys2.jpg" style="width: 404px; height: 245px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot;@.a.#&quot;,&quot;###.#&quot;,&quot;b.A.B&quot;]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> Note that the goal is to obtain all the keys not to open all the locks.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-key2.jpg" style="width: 404px; height: 245px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot;@..aA&quot;,&quot;..B#.&quot;,&quot;....b&quot;]
-<strong>Output:</strong> 6
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-keys3.jpg" style="width: 244px; height: 85px;" />
-<pre>
-<strong>Input:</strong> grid = [&quot;@Aa&quot;]
-<strong>Output:</strong> -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 30</code></li>
-	<li><code>grid[i][j]</code> is either an English letter, <code>&#39;.&#39;</code>, <code>&#39;#&#39;</code>, or <code>&#39;@&#39;</code>.</li>
-	<li>The number of keys in the grid is in the range <code>[1, 6]</code>.</li>
-	<li>Each key in the grid is <strong>unique</strong>.</li>
-	<li>Each key in the grid has a matching lock.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
diff --git a/problems/shortest-path-to-get-all-keys/shortest_path_to_get_all_keys.go b/problems/shortest-path-to-get-all-keys/shortest_path_to_get_all_keys.go
deleted file mode 100644
index 0c0ac7625..000000000
--- a/problems/shortest-path-to-get-all-keys/shortest_path_to_get_all_keys.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem864
diff --git a/problems/shortest-path-to-get-all-keys/shortest_path_to_get_all_keys_test.go b/problems/shortest-path-to-get-all-keys/shortest_path_to_get_all_keys_test.go
deleted file mode 100644
index 0c0ac7625..000000000
--- a/problems/shortest-path-to-get-all-keys/shortest_path_to_get_all_keys_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem864
diff --git a/problems/shortest-path-to-get-food/README.md b/problems/shortest-path-to-get-food/README.md
deleted file mode 100644
index d6251d5c9..000000000
--- a/problems/shortest-path-to-get-food/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-followers-count "Find Followers Count")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-employees-which-report-to-each-employee "The Number of Employees Which Report to Each Employee")
-
-## [1730. Shortest Path to Get Food (Medium)](https://leetcode.com/problems/shortest-path-to-get-food "获取食物的最短路径")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [01 Matrix](../01-matrix) (Medium)
-  1. [Shortest Path in a Grid with Obstacles Elimination](../shortest-path-in-a-grid-with-obstacles-elimination) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Run BFS starting from the '*' position.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep the current number of the steps as a state in the queue.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The first time you reach a food, return the number of steps as the answer.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-In case the queue is empty and you still did not manage to reach a food, return -1.
-</details>
diff --git a/problems/shortest-path-visiting-all-nodes/README.md b/problems/shortest-path-visiting-all-nodes/README.md
deleted file mode 100644
index 77c4a02d2..000000000
--- a/problems/shortest-path-visiting-all-nodes/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../hand-of-straights "Hand of Straights")
-　　　　　　　　　　　　　　　　
-[Next >](../shifting-letters "Shifting Letters")
-
-## [847. Shortest Path Visiting All Nodes (Hard)](https://leetcode.com/problems/shortest-path-visiting-all-nodes "访问所有节点的最短路径")
-
-<p>You have an undirected, connected graph of <code>n</code> nodes labeled from <code>0</code> to <code>n - 1</code>. You are given an array <code>graph</code> where <code>graph[i]</code> is a list of all the nodes connected with node <code>i</code> by an edge.</p>
-
-<p>Return <em>the length of the shortest path that visits every node</em>. You may start and stop at any node, you may revisit nodes multiple times, and you may reuse edges.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/12/shortest1-graph.jpg" style="width: 222px; height: 183px;" />
-<pre>
-<strong>Input:</strong> graph = [[1,2,3],[0],[0],[0]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> One possible path is [1,0,2,0,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/12/shortest2-graph.jpg" style="width: 382px; height: 222px;" />
-<pre>
-<strong>Input:</strong> graph = [[1],[0,2,4],[1,3,4],[2],[1,2]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> One possible path is [0,1,4,2,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == graph.length</code></li>
-	<li><code>1 &lt;= n &lt;= 12</code></li>
-	<li><code>0 &lt;= graph[i].length &lt;&nbsp;n</code></li>
-	<li><code>graph[i]</code> does not contain <code>i</code>.</li>
-	<li>If <code>graph[a]</code> contains <code>b</code>, then <code>graph[b]</code> contains <code>a</code>.</li>
-	<li>The input graph is always connected.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
diff --git a/problems/shortest-path-visiting-all-nodes/shortest_path_visiting_all_nodes.go b/problems/shortest-path-visiting-all-nodes/shortest_path_visiting_all_nodes.go
deleted file mode 100644
index ef11f7e74..000000000
--- a/problems/shortest-path-visiting-all-nodes/shortest_path_visiting_all_nodes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem847
diff --git a/problems/shortest-path-visiting-all-nodes/shortest_path_visiting_all_nodes_test.go b/problems/shortest-path-visiting-all-nodes/shortest_path_visiting_all_nodes_test.go
deleted file mode 100644
index ef11f7e74..000000000
--- a/problems/shortest-path-visiting-all-nodes/shortest_path_visiting_all_nodes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem847
diff --git a/problems/shortest-path-with-alternating-colors/README.md b/problems/shortest-path-with-alternating-colors/README.md
deleted file mode 100644
index 4412b632c..000000000
--- a/problems/shortest-path-with-alternating-colors/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-equivalent-domino-pairs "Number of Equivalent Domino Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-tree-from-leaf-values "Minimum Cost Tree From Leaf Values")
-
-## [1129. Shortest Path with Alternating Colors (Medium)](https://leetcode.com/problems/shortest-path-with-alternating-colors "颜色交替的最短路径")
-
-<p>Consider a directed graph, with nodes labelled <code>0, 1, ..., n-1</code>.&nbsp; In this graph, each edge is either red or blue, and there could&nbsp;be self-edges or parallel edges.</p>
-
-<p>Each <code>[i, j]</code> in <code>red_edges</code> denotes a red directed edge from node <code>i</code> to node <code>j</code>.&nbsp; Similarly, each <code>[i, j]</code> in <code>blue_edges</code> denotes a blue directed edge from node <code>i</code> to node <code>j</code>.</p>
-
-<p>Return an array <code>answer</code>&nbsp;of length <code>n</code>,&nbsp;where each&nbsp;<code>answer[X]</code>&nbsp;is&nbsp;the length of the shortest path from node <code>0</code>&nbsp;to node <code>X</code>&nbsp;such that the edge colors alternate along the path (or <code>-1</code> if such a path doesn&#39;t exist).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> n = 3, red_edges = [[0,1],[1,2]], blue_edges = []
-<strong>Output:</strong> [0,1,-1]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> n = 3, red_edges = [[0,1]], blue_edges = [[2,1]]
-<strong>Output:</strong> [0,1,-1]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> n = 3, red_edges = [[1,0]], blue_edges = [[2,1]]
-<strong>Output:</strong> [0,-1,-1]
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> n = 3, red_edges = [[0,1]], blue_edges = [[1,2]]
-<strong>Output:</strong> [0,1,2]
-</pre><p><strong>Example 5:</strong></p>
-<pre><strong>Input:</strong> n = 3, red_edges = [[0,1],[0,2]], blue_edges = [[1,0]]
-<strong>Output:</strong> [0,1,1]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>red_edges.length &lt;= 400</code></li>
-	<li><code>blue_edges.length &lt;= 400</code></li>
-	<li><code>red_edges[i].length == blue_edges[i].length == 2</code></li>
-	<li><code>0 &lt;= red_edges[i][j], blue_edges[i][j] &lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do a breadth-first search, where the "nodes" are actually (Node, color of last edge taken).
-</details>
diff --git a/problems/shortest-subarray-to-be-removed-to-make-array-sorted/README.md b/problems/shortest-subarray-to-be-removed-to-make-array-sorted/README.md
deleted file mode 100644
index 6af342eff..000000000
--- a/problems/shortest-subarray-to-be-removed-to-make-array-sorted/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-ways-to-split-a-string "Number of Ways to Split a String")
-　　　　　　　　　　　　　　　　
-[Next >](../count-all-possible-routes "Count All Possible Routes")
-
-## [1574. Shortest Subarray to be Removed to Make Array Sorted (Medium)](https://leetcode.com/problems/shortest-subarray-to-be-removed-to-make-array-sorted "删除最短的子数组使剩余数组有序")
-
-<p>Given an integer array <code>arr</code>, remove a subarray (can be empty) from <code>arr</code> such that the remaining elements in <code>arr</code> are <strong>non-decreasing</strong>.</p>
-
-<p>Return <em>the length of the shortest subarray to remove</em>.</p>
-
-<p>A <strong>subarray</strong> is a contiguous subsequence of the array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,10,4,2,3,5]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The shortest subarray we can remove is [10,4,2] of length 3. The remaining elements after that will be [1,2,3,3,5] which are sorted.
-Another correct solution is to remove the subarray [3,10,4].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [5,4,3,2,1]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Since the array is strictly decreasing, we can only keep a single element. Therefore we need to remove a subarray of length 4, either [5,4,3,2] or [4,3,2,1].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The array is already non-decreasing. We do not need to remove any elements.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The key is to find the longest non-decreasing subarray starting with the first element or ending with the last element, respectively.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After removing some subarray, the result is the concatenation of a sorted prefix and a sorted suffix, where the last element of the prefix is smaller than the first element of the suffix.
-</details>
diff --git a/problems/shortest-subarray-with-sum-at-least-k/README.md b/problems/shortest-subarray-with-sum-at-least-k/README.md
deleted file mode 100644
index 73131621a..000000000
--- a/problems/shortest-subarray-with-sum-at-least-k/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../score-after-flipping-matrix "Score After Flipping Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../all-nodes-distance-k-in-binary-tree "All Nodes Distance K in Binary Tree")
-
-## [862. Shortest Subarray with Sum at Least K (Hard)](https://leetcode.com/problems/shortest-subarray-with-sum-at-least-k "和至少为 K 的最短子数组")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the length of the shortest non-empty <strong>subarray</strong> of </em><code>nums</code><em> with a sum of at least </em><code>k</code>. If there is no such <strong>subarray</strong>, return <code>-1</code>.</p>
-
-<p>A <strong>subarray</strong> is a <strong>contiguous</strong> part of an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1], k = 1
-<strong>Output:</strong> 1
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2], k = 4
-<strong>Output:</strong> -1
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [2,-1,2], k = 3
-<strong>Output:</strong> 3
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= k &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Monotonic Queue](../../tag/monotonic-queue/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
diff --git a/problems/shortest-subarray-with-sum-at-least-k/shortest_subarray_with_sum_at_least_k.go b/problems/shortest-subarray-with-sum-at-least-k/shortest_subarray_with_sum_at_least_k.go
deleted file mode 100644
index fec6234d4..000000000
--- a/problems/shortest-subarray-with-sum-at-least-k/shortest_subarray_with_sum_at_least_k.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem862
diff --git a/problems/shortest-subarray-with-sum-at-least-k/shortest_subarray_with_sum_at_least_k_test.go b/problems/shortest-subarray-with-sum-at-least-k/shortest_subarray_with_sum_at_least_k_test.go
deleted file mode 100644
index fec6234d4..000000000
--- a/problems/shortest-subarray-with-sum-at-least-k/shortest_subarray_with_sum_at_least_k_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem862
diff --git a/problems/shortest-unsorted-continuous-subarray/README.md b/problems/shortest-unsorted-continuous-subarray/README.md
deleted file mode 100644
index 4727ed77a..000000000
--- a/problems/shortest-unsorted-continuous-subarray/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-student-number-in-departments "Count Student Number in Departments")
-　　　　　　　　　　　　　　　　
-[Next >](../kill-process "Kill Process")
-
-## [581. Shortest Unsorted Continuous Subarray (Medium)](https://leetcode.com/problems/shortest-unsorted-continuous-subarray "最短无序连续子数组")
-
-<p>Given an integer array <code>nums</code>, you need to find one <b>continuous subarray</b> that if you only sort this subarray in ascending order, then the whole array will be sorted in ascending order.</p>
-
-<p>Return <em>the shortest such subarray and output its length</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,6,4,8,10,9,15]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> You need to sort [6, 4, 8, 10, 9] in ascending order to make the whole array sorted in ascending order.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Can you solve it in <code>O(n)</code> time complexity?
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
diff --git a/problems/shortest-unsorted-continuous-subarray/shortest_unsorted_continuous_subarray.go b/problems/shortest-unsorted-continuous-subarray/shortest_unsorted_continuous_subarray.go
deleted file mode 100644
index eef20a643..000000000
--- a/problems/shortest-unsorted-continuous-subarray/shortest_unsorted_continuous_subarray.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem581
-
-func findUnsortedSubarray(nums []int) int {
-	m, n, l := 0, -1, len(nums)
-	for max, min, i, j := 0, l-1, 1, l-2; i < l; i, j = i+1, j-1 {
-		if nums[i] < nums[max] {
-			n = i
-		} else if nums[i] > nums[max] {
-			max = i
-		}
-		if nums[j] > nums[min] {
-			m = j
-		} else if nums[j] < nums[min] {
-			min = j
-		}
-	}
-	return n - m + 1
-}
diff --git a/problems/shortest-unsorted-continuous-subarray/shortest_unsorted_continuous_subarray_test.go b/problems/shortest-unsorted-continuous-subarray/shortest_unsorted_continuous_subarray_test.go
deleted file mode 100644
index 3a3a4f987..000000000
--- a/problems/shortest-unsorted-continuous-subarray/shortest_unsorted_continuous_subarray_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem581
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestFindUnsortedSubarray(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{2, 6, 4, 8, 10, 9, 15},
-			want: 5,
-		},
-		{
-			in:   []int{1, 2, 3, 4},
-			want: 0,
-		},
-		{
-			in:   []int{1, 2, 4, 5, 3},
-			want: 3,
-		},
-	}
-	for _, tt := range tests {
-		got := findUnsortedSubarray(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/shortest-way-to-form-string/README.md b/problems/shortest-way-to-form-string/README.md
deleted file mode 100644
index 2a8fb3a4b..000000000
--- a/problems/shortest-way-to-form-string/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distant-barcodes "Distant Barcodes")
-　　　　　　　　　　　　　　　　
-[Next >](../confusing-number "Confusing Number")
-
-## [1055. Shortest Way to Form String (Medium)](https://leetcode.com/problems/shortest-way-to-form-string "形成字符串的最短路径")
-
-<p>From any string, we can form a <i>subsequence</i> of that string by deleting some number of characters (possibly no deletions).</p>
-
-<p>Given two strings <code>source</code> and <code>target</code>, return the minimum number of subsequences of <code>source</code> such that their concatenation equals <code>target</code>. If the task is impossible, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>source = <span id="example-input-1-1">&quot;abc&quot;</span>, target = <span id="example-input-1-2">&quot;abcbc&quot;</span>
-<strong>Output: </strong><span id="example-output-1">2</span>
-<strong>Explanation: </strong>The target &quot;abcbc&quot; can be formed by &quot;abc&quot; and &quot;bc&quot;, which are subsequences of source &quot;abc&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>source = <span id="example-input-2-1">&quot;abc&quot;</span>, target = <span id="example-input-2-2">&quot;acdbc&quot;</span>
-<strong>Output: </strong><span id="example-output-2">-1</span>
-<strong>Explanation: </strong>The target string cannot be constructed from the subsequences of source string due to the character &quot;d&quot; in target string.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input: </strong>source = <span id="example-input-3-1">&quot;xyz&quot;</span>, target = <span id="example-input-3-2">&quot;xzyxz&quot;</span>
-<strong>Output: </strong><span id="example-output-3">3</span>
-<strong>Explanation: </strong>The target string can be constructed as follows &quot;xz&quot; + &quot;y&quot; + &quot;xz&quot;.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>Both the <code>source</code> and <code>target</code> strings consist of only lowercase English letters from &quot;a&quot;-&quot;z&quot;.</li>
-	<li>The lengths of <code>source</code> and <code>target</code> string are between <code>1</code> and <code>1000</code>.</li>
-</ol>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Is Subsequence](../is-subsequence) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Which conditions have to been met in order to be impossible to form the target string?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If there exists a character in the target string which doesn't exist in the source string then it will be impossible to form the target string.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Assuming we are in the case which is possible to form the target string, how can we assure the minimum number of used subsequences of source?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For each used subsequence try to match the leftmost character of the current subsequence with the leftmost character of the target string, if they match then erase both character otherwise erase just the subsequence character whenever the current subsequence gets empty, reset it to a new copy of subsequence and increment the count, do this until the target sequence gets empty. Finally return the count.
-</details>
diff --git a/problems/shortest-word-distance-ii/README.md b/problems/shortest-word-distance-ii/README.md
deleted file mode 100644
index d353dc002..000000000
--- a/problems/shortest-word-distance-ii/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-word-distance "Shortest Word Distance")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-word-distance-iii "Shortest Word Distance III")
-
-## [244. Shortest Word Distance II (Medium)](https://leetcode.com/problems/shortest-word-distance-ii "最短单词距离 II")
-
-<p>Design a class which receives a list of words in the constructor, and implements a method that takes two words <em>word1</em> and <em>word2</em> and return the shortest distance between these two words in the list. Your method will be called <em>repeatedly</em> many times with different parameters.&nbsp;</p>
-
-<p><strong>Example:</strong><br />
-Assume that words = <code>[&quot;practice&quot;, &quot;makes&quot;, &quot;perfect&quot;, &quot;coding&quot;, &quot;makes&quot;]</code>.</p>
-
-<pre><b>Input:</b> <em>word1</em> = <code>&ldquo;coding&rdquo;</code>, <em>word2</em> = <code>&ldquo;practice&rdquo;</code>
-<b>Output:</b> 3
-</pre>
-
-<pre><b>Input:</b> <em>word1</em> = <code>&quot;makes&quot;</code>, <em>word2</em> = <code>&quot;coding&quot;</code>
-<b>Output:</b> 1</pre>
-
-<p><strong>Note:</strong><br />
-You may assume that <em>word1</em> <strong>does not equal to</strong> <em>word2</em>, and <em>word1</em> and <em>word2</em> are both in the list.</p>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Merge Two Sorted Lists](../merge-two-sorted-lists) (Easy)
-  1. [Shortest Word Distance](../shortest-word-distance) (Easy)
-  1. [Shortest Word Distance III](../shortest-word-distance-iii) (Medium)
diff --git a/problems/shortest-word-distance-ii/shortest_word_distance_ii.go b/problems/shortest-word-distance-ii/shortest_word_distance_ii.go
deleted file mode 100644
index ee8158beb..000000000
--- a/problems/shortest-word-distance-ii/shortest_word_distance_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem244
diff --git a/problems/shortest-word-distance-ii/shortest_word_distance_ii_test.go b/problems/shortest-word-distance-ii/shortest_word_distance_ii_test.go
deleted file mode 100644
index ee8158beb..000000000
--- a/problems/shortest-word-distance-ii/shortest_word_distance_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem244
diff --git a/problems/shortest-word-distance-iii/README.md b/problems/shortest-word-distance-iii/README.md
deleted file mode 100644
index a3dfa9687..000000000
--- a/problems/shortest-word-distance-iii/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-word-distance-ii "Shortest Word Distance II")
-　　　　　　　　　　　　　　　　
-[Next >](../strobogrammatic-number "Strobogrammatic Number")
-
-## [245. Shortest Word Distance III (Medium)](https://leetcode.com/problems/shortest-word-distance-iii "最短单词距离 III")
-
-<p>Given a list of words and two words <em>word1</em> and <em>word2</em>, return the shortest distance between these two words in the list.</p>
-
-<p><em>word1</em> and <em>word2</em> may be the same and they represent two individual words in the list.</p>
-
-<p><strong>Example:</strong><br />
-Assume that words = <code>[&quot;practice&quot;, &quot;makes&quot;, &quot;perfect&quot;, &quot;coding&quot;, &quot;makes&quot;]</code>.</p>
-
-<pre>
-<b>Input:</b> <em>word1</em> = <code>&ldquo;makes&rdquo;</code>, <em>word2</em> = <code>&ldquo;coding&rdquo;</code>
-<b>Output:</b> 1
-</pre>
-
-<pre>
-<b>Input:</b> <em>word1</em> = <code>&quot;makes&quot;</code>, <em>word2</em> = <code>&quot;makes&quot;</code>
-<b>Output:</b> 3
-</pre>
-
-<p><strong>Note:</strong><br />
-You may assume <em>word1</em> and <em>word2</em> are both in the list.</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Shortest Word Distance](../shortest-word-distance) (Easy)
-  1. [Shortest Word Distance II](../shortest-word-distance-ii) (Medium)
diff --git a/problems/shortest-word-distance-iii/shortest_word_distance_iii.go b/problems/shortest-word-distance-iii/shortest_word_distance_iii.go
deleted file mode 100644
index 528535a3e..000000000
--- a/problems/shortest-word-distance-iii/shortest_word_distance_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem245
diff --git a/problems/shortest-word-distance-iii/shortest_word_distance_iii_test.go b/problems/shortest-word-distance-iii/shortest_word_distance_iii_test.go
deleted file mode 100644
index 528535a3e..000000000
--- a/problems/shortest-word-distance-iii/shortest_word_distance_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem245
diff --git a/problems/shortest-word-distance/README.md b/problems/shortest-word-distance/README.md
deleted file mode 100644
index 13002efde..000000000
--- a/problems/shortest-word-distance/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-anagram "Valid Anagram")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-word-distance-ii "Shortest Word Distance II")
-
-## [243. Shortest Word Distance (Easy)](https://leetcode.com/problems/shortest-word-distance "最短单词距离")
-
-<p>Given a list of words and two words <em>word1</em> and <em>word2</em>, return the shortest distance between these two words in the list.</p>
-
-<p><strong>Example:</strong><br />
-Assume that words = <code>[&quot;practice&quot;, &quot;makes&quot;, &quot;perfect&quot;, &quot;coding&quot;, &quot;makes&quot;]</code>.</p>
-
-<pre>
-<b>Input:</b> <em>word1</em> = <code>&ldquo;coding&rdquo;</code>, <em>word2</em> = <code>&ldquo;practice&rdquo;</code>
-<b>Output:</b> 3
-</pre>
-
-<pre>
-<b>Input:</b> <em>word1</em> = <code>&quot;makes&quot;</code>, <em>word2</em> = <code>&quot;coding&quot;</code>
-<b>Output:</b> 1
-</pre>
-
-<p><strong>Note:</strong><br />
-You may assume that <em>word1</em> <strong>does not equal to</strong> <em>word2</em>, and <em>word1</em> and <em>word2</em> are both in the list.</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Shortest Word Distance II](../shortest-word-distance-ii) (Medium)
-  1. [Shortest Word Distance III](../shortest-word-distance-iii) (Medium)
diff --git a/problems/shortest-word-distance/shortest_word_distance.go b/problems/shortest-word-distance/shortest_word_distance.go
deleted file mode 100644
index a26bbb5f6..000000000
--- a/problems/shortest-word-distance/shortest_word_distance.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem243
diff --git a/problems/shortest-word-distance/shortest_word_distance_test.go b/problems/shortest-word-distance/shortest_word_distance_test.go
deleted file mode 100644
index a26bbb5f6..000000000
--- a/problems/shortest-word-distance/shortest_word_distance_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem243
diff --git a/problems/shuffle-an-array/README.md b/problems/shuffle-an-array/README.md
deleted file mode 100644
index 9ac2b877c..000000000
--- a/problems/shuffle-an-array/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ransom-note "Ransom Note")
-　　　　　　　　　　　　　　　　
-[Next >](../mini-parser "Mini Parser")
-
-## [384. Shuffle an Array (Medium)](https://leetcode.com/problems/shuffle-an-array "打乱数组")
-
-<p>Given an integer array <code>nums</code>, design an algorithm to randomly shuffle the array. All permutations of the array should be <strong>equally likely</strong> as a result of the shuffling.</p>
-
-<p>Implement the <code>Solution</code> class:</p>
-
-<ul>
-	<li><code>Solution(int[] nums)</code> Initializes the object with the integer array <code>nums</code>.</li>
-	<li><code>int[] reset()</code> Resets the array to its original configuration and returns it.</li>
-	<li><code>int[] shuffle()</code> Returns a random shuffling of the array.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Solution&quot;, &quot;shuffle&quot;, &quot;reset&quot;, &quot;shuffle&quot;]
-[[[1, 2, 3]], [], [], []]
-<strong>Output</strong>
-[null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]
-
-<strong>Explanation</strong>
-Solution solution = new Solution([1, 2, 3]);
-solution.shuffle();    // Shuffle the array [1,2,3] and return its result.
-                       // Any permutation of [1,2,3] must be equally likely to be returned.
-                       // Example: return [3, 1, 2]
-solution.reset();      // Resets the array back to its original configuration [1,2,3]. Return [1, 2, 3]
-solution.shuffle();    // Returns the random shuffling of array [1,2,3]. Example: return [1, 3, 2]
-
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 200</code></li>
-	<li><code>-10<sup>6</sup> &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-	<li>All the elements of <code>nums</code> are <strong>unique</strong>.</li>
-	<li>At most <code>5 * 10<sup>4</sup></code> calls <strong>in total</strong> will be made to <code>reset</code> and <code>shuffle</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Randomized](../../tag/randomized/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The solution expects that we always use the original array to shuffle() else some of the test cases fail. (Credits; @snehasingh31)
-</details>
diff --git a/problems/shuffle-an-array/shuffle_an_array.go b/problems/shuffle-an-array/shuffle_an_array.go
deleted file mode 100644
index 39eaeac2e..000000000
--- a/problems/shuffle-an-array/shuffle_an_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem384
diff --git a/problems/shuffle-an-array/shuffle_an_array_test.go b/problems/shuffle-an-array/shuffle_an_array_test.go
deleted file mode 100644
index 39eaeac2e..000000000
--- a/problems/shuffle-an-array/shuffle_an_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem384
diff --git a/problems/shuffle-string/README.md b/problems/shuffle-string/README.md
deleted file mode 100644
index ab3bf2124..000000000
--- a/problems/shuffle-string/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../patients-with-a-condition "Patients With a Condition")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-suffix-flips "Minimum Suffix Flips")
-
-## [1528. Shuffle String (Easy)](https://leetcode.com/problems/shuffle-string "重新排列字符串")
-
-<p>You are given a string <code>s</code> and an integer array <code>indices</code> of the <strong>same length</strong>. The string <code>s</code> will be shuffled such that the character at the <code>i<sup>th</sup></code> position moves to <code>indices[i]</code> in the shuffled string.</p>
-
-<p>Return <em>the shuffled string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/09/q1.jpg" style="width: 321px; height: 243px;" />
-<pre>
-<strong>Input:</strong> s = &quot;codeleet&quot;, <code>indices</code> = [4,5,6,7,0,2,1,3]
-<strong>Output:</strong> &quot;leetcode&quot;
-<strong>Explanation:</strong> As shown, &quot;codeleet&quot; becomes &quot;leetcode&quot; after shuffling.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;, <code>indices</code> = [0,1,2]
-<strong>Output:</strong> &quot;abc&quot;
-<strong>Explanation:</strong> After shuffling, each character remains in its position.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>s.length == indices.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-	<li><code>0 &lt;= indices[i] &lt; n</code></li>
-	<li>All values of <code>indices</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can create an auxiliary string t of length n.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Assign t[indexes[i]] to s[i] for each i from 0 to n-1.
-</details>
diff --git a/problems/shuffle-the-array/README.md b/problems/shuffle-the-array/README.md
deleted file mode 100644
index 9180ca6d1..000000000
--- a/problems/shuffle-the-array/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-all-the-lonely-nodes "Find All The Lonely Nodes")
-　　　　　　　　　　　　　　　　
-[Next >](../the-k-strongest-values-in-an-array "The k Strongest Values in an Array")
-
-## [1470. Shuffle the Array (Easy)](https://leetcode.com/problems/shuffle-the-array "重新排列数组")
-
-<p>Given the array <code>nums</code> consisting of <code>2n</code> elements in the form <code>[x<sub>1</sub>,x<sub>2</sub>,...,x<sub>n</sub>,y<sub>1</sub>,y<sub>2</sub>,...,y<sub>n</sub>]</code>.</p>
-
-<p><em>Return the array in the form</em> <code>[x<sub>1</sub>,y<sub>1</sub>,x<sub>2</sub>,y<sub>2</sub>,...,x<sub>n</sub>,y<sub>n</sub>]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,5,1,3,4,7], n = 3
-<strong>Output:</strong> [2,3,5,4,1,7] 
-<strong>Explanation:</strong> Since x<sub>1</sub>=2, x<sub>2</sub>=5, x<sub>3</sub>=1, y<sub>1</sub>=3, y<sub>2</sub>=4, y<sub>3</sub>=7 then the answer is [2,3,5,4,1,7].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,4,3,2,1], n = 4
-<strong>Output:</strong> [1,4,2,3,3,2,4,1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,2,2], n = 2
-<strong>Output:</strong> [1,2,1,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 500</code></li>
-	<li><code>nums.length == 2n</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10^3</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use two pointers to create the new array of 2n elements. The first starting at the beginning and the other starting at (n+1)th position. Alternate between them and create the new array.
-</details>
diff --git a/problems/sign-of-the-product-of-an-array/README.md b/problems/sign-of-the-product-of-an-array/README.md
deleted file mode 100644
index 2ce92356b..000000000
--- a/problems/sign-of-the-product-of-an-array/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-customers-with-positive-revenue-this-year "Find Customers With Positive Revenue this Year")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-winner-of-the-circular-game "Find the Winner of the Circular Game")
-
-## [1822. Sign of the Product of an Array (Easy)](https://leetcode.com/problems/sign-of-the-product-of-an-array "数组元素积的符号")
-
-<p>There is a function <code>signFunc(x)</code> that returns:</p>
-
-<ul>
-	<li><code>1</code> if <code>x</code> is positive.</li>
-	<li><code>-1</code> if <code>x</code> is negative.</li>
-	<li><code>0</code> if <code>x</code> is equal to <code>0</code>.</li>
-</ul>
-
-<p>You are given an integer array <code>nums</code>. Let <code>product</code> be the product of all values in the array <code>nums</code>.</p>
-
-<p>Return <code>signFunc(product)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,-2,-3,-4,3,2,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The product of all values in the array is 144, and signFunc(144) = 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5,0,2,-3]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The product of all values in the array is 0, and signFunc(0) = 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,1,-1,1,-1]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> The product of all values in the array is -1, and signFunc(-1) = -1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If there is a 0 in the array the answer is 0
-</details>
-
-<details>
-<summary>Hint 2</summary>
-To avoid overflow make all the negative numbers -1 and all positive numbers 1 and calculate the prod
-</details>
diff --git a/problems/similar-rgb-color/README.md b/problems/similar-rgb-color/README.md
deleted file mode 100644
index da973a626..000000000
--- a/problems/similar-rgb-color/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../champagne-tower "Champagne Tower")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-swaps-to-make-sequences-increasing "Minimum Swaps To Make Sequences Increasing")
-
-## [800. Similar RGB Color (Easy)](https://leetcode.com/problems/similar-rgb-color "相似 RGB 颜色")
-
-<p>In the following, every capital letter represents some hexadecimal digit from <code>0</code> to <code>f</code>.</p>
-
-<p>The red-green-blue color <code>&quot;#AABBCC&quot;</code>&nbsp;can be written&nbsp;as&nbsp;<code>&quot;#ABC&quot;</code> in&nbsp;shorthand.&nbsp; For example, <code>&quot;#15c&quot;</code> is shorthand for the color <code>&quot;#1155cc&quot;</code>.</p>
-
-<p>Now, say the similarity between two colors <code>&quot;#ABCDEF&quot;</code> and <code>&quot;#UVWXYZ&quot;</code> is <code>-(AB - UV)^2 -&nbsp;(CD - WX)^2 -&nbsp;(EF - YZ)^2</code>.</p>
-
-<p>Given the color <code>&quot;#ABCDEF&quot;</code>, return a 7 character color&nbsp;that is most similar to <code>#ABCDEF</code>, and has a shorthand (that is, it can be represented as some <code>&quot;#XYZ&quot;</code></p>
-
-<pre>
-<strong>Example 1:</strong>
-<strong>Input:</strong> color = &quot;#09f166&quot;
-<strong>Output:</strong> &quot;#11ee66&quot;
-<strong>Explanation: </strong> 
-The similarity is -(0x09 - 0x11)^2 -(0xf1 - 0xee)^2 - (0x66 - 0x66)^2 = -64 -9 -0 = -73.
-This is the highest among any shorthand color.
-</pre>
-
-<p><strong>Note:</strong></p>
-
-<ul>
-	<li><code>color</code> is a string of length <code>7</code>.</li>
-	<li><code>color</code> is a valid RGB color: for <code>i &gt; 0</code>, <code>color[i]</code> is a hexadecimal digit from <code>0</code> to <code>f</code></li>
-	<li>Any answer which has the same (highest)&nbsp;similarity as the best answer will be accepted.</li>
-	<li>All inputs and outputs should use lowercase letters, and the output is 7 characters.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
diff --git a/problems/similar-rgb-color/similar_rgb_color.go b/problems/similar-rgb-color/similar_rgb_color.go
deleted file mode 100644
index 21fa167d0..000000000
--- a/problems/similar-rgb-color/similar_rgb_color.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem800
diff --git a/problems/similar-rgb-color/similar_rgb_color_test.go b/problems/similar-rgb-color/similar_rgb_color_test.go
deleted file mode 100644
index 21fa167d0..000000000
--- a/problems/similar-rgb-color/similar_rgb_color_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem800
diff --git a/problems/similar-string-groups/README.md b/problems/similar-string-groups/README.md
deleted file mode 100644
index a0c747ba5..000000000
--- a/problems/similar-string-groups/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../push-dominoes "Push Dominoes")
-　　　　　　　　　　　　　　　　
-[Next >](../magic-squares-in-grid "Magic Squares In Grid")
-
-## [839. Similar String Groups (Hard)](https://leetcode.com/problems/similar-string-groups "相似字符串组")
-
-<p>Two strings <code>X</code>&nbsp;and <code>Y</code>&nbsp;are similar if we can swap two letters (in different positions) of <code>X</code>, so that&nbsp;it equals <code>Y</code>. Also two strings <code>X</code> and <code>Y</code> are similar if they are equal.</p>
-
-<p>For example, <code>&quot;tars&quot;</code>&nbsp;and <code>&quot;rats&quot;</code>&nbsp;are similar (swapping at positions <code>0</code> and <code>2</code>), and <code>&quot;rats&quot;</code> and <code>&quot;arts&quot;</code> are similar, but <code>&quot;star&quot;</code> is not similar to <code>&quot;tars&quot;</code>, <code>&quot;rats&quot;</code>, or <code>&quot;arts&quot;</code>.</p>
-
-<p>Together, these form two connected groups by similarity: <code>{&quot;tars&quot;, &quot;rats&quot;, &quot;arts&quot;}</code> and <code>{&quot;star&quot;}</code>.&nbsp; Notice that <code>&quot;tars&quot;</code> and <code>&quot;arts&quot;</code> are in the same group even though they are not similar.&nbsp; Formally, each group is such that a word is in the group if and only if it is similar to at least one other word in the group.</p>
-
-<p>We are given a list <code>strs</code> of strings where every string in <code>strs</code> is an anagram of every other string in <code>strs</code>. How many groups are there?</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;tars&quot;,&quot;rats&quot;,&quot;arts&quot;,&quot;star&quot;]
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> strs = [&quot;omv&quot;,&quot;ovm&quot;]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= strs.length &lt;= 300</code></li>
-	<li><code>1 &lt;= strs[i].length &lt;= 300</code></li>
-	<li><code>strs[i]</code> consists of lowercase letters only.</li>
-	<li>All words in <code>strs</code> have the same length and are anagrams of each other.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/similar-string-groups/similar_string_groups.go b/problems/similar-string-groups/similar_string_groups.go
deleted file mode 100644
index 6cceadfa6..000000000
--- a/problems/similar-string-groups/similar_string_groups.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem839
diff --git a/problems/similar-string-groups/similar_string_groups_test.go b/problems/similar-string-groups/similar_string_groups_test.go
deleted file mode 100644
index 6cceadfa6..000000000
--- a/problems/similar-string-groups/similar_string_groups_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem839
diff --git a/problems/simple-bank-system/README.md b/problems/simple-bank-system/README.md
deleted file mode 100644
index 21519e1c9..000000000
--- a/problems/simple-bank-system/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-numbers-are-ascending-in-a-sentence "Check if Numbers Are Ascending in a Sentence")
-　　　　　　　　　　　　　　　　
-[Next >](../count-number-of-maximum-bitwise-or-subsets "Count Number of Maximum Bitwise-OR Subsets")
-
-## [2043. Simple Bank System (Medium)](https://leetcode.com/problems/simple-bank-system "简易银行系统")
-
-<p>You have been tasked with writing a program for a popular bank that will automate all its incoming transactions (transfer, deposit, and withdraw). The bank has <code>n</code> accounts numbered from <code>1</code> to <code>n</code>. The initial balance of each account is stored in a <strong>0-indexed</strong> integer array <code>balance</code>, with the <code>(i + 1)<sup>th</sup></code> account having an initial balance of <code>balance[i]</code>.</p>
-
-<p>Execute all the <strong>valid</strong> transactions. A transaction is <strong>valid</strong> if:</p>
-
-<ul>
-	<li>The given account number(s) are between <code>1</code> and <code>n</code>, and</li>
-	<li>The amount of money withdrawn or transferred from is <strong>less than or equal</strong> to the balance of the account.</li>
-</ul>
-
-<p>Implement the <code>Bank</code> class:</p>
-
-<ul>
-	<li><code>Bank(long[] balance)</code> Initializes the object with the <strong>0-indexed</strong> integer array <code>balance</code>.</li>
-	<li><code>boolean transfer(int account1, int account2, long money)</code> Transfers <code>money</code> dollars from the account numbered <code>account1</code> to the account numbered <code>account2</code>. Return <code>true</code> if the transaction was successful, <code>false</code> otherwise.</li>
-	<li><code>boolean deposit(int account, long money)</code> Deposit <code>money</code> dollars into the account numbered <code>account</code>. Return <code>true</code> if the transaction was successful, <code>false</code> otherwise.</li>
-	<li><code>boolean withdraw(int account, long money)</code> Withdraw <code>money</code> dollars from the account numbered <code>account</code>. Return <code>true</code> if the transaction was successful, <code>false</code> otherwise.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;Bank&quot;, &quot;withdraw&quot;, &quot;transfer&quot;, &quot;deposit&quot;, &quot;transfer&quot;, &quot;withdraw&quot;]
-[[[10, 100, 20, 50, 30]], [3, 10], [5, 1, 20], [5, 20], [3, 4, 15], [10, 50]]
-<strong>Output</strong>
-[null, true, true, true, false, false]
-
-<strong>Explanation</strong>
-Bank bank = new Bank([10, 100, 20, 50, 30]);
-bank.withdraw(3, 10);    // return true, account 3 has a balance of $20, so it is valid to withdraw $10.
-                         // Account 3 has $20 - $10 = $10.
-bank.transfer(5, 1, 20); // return true, account 5 has a balance of $30, so it is valid to transfer $20.
-                         // Account 5 has $30 - $20 = $10, and account 1 has $10 + $20 = $30.
-bank.deposit(5, 20);     // return true, it is valid to deposit $20 to account 5.
-                         // Account 5 has $10 + $20 = $30.
-bank.transfer(3, 4, 15); // return false, the current balance of account 3 is $10,
-                         // so it is invalid to transfer $15 from it.
-bank.withdraw(10, 50);   // return false, it is invalid because account 10 does not exist.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == balance.length</code></li>
-	<li><code>1 &lt;= n, account, account1, account2 &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= balance[i], money &lt;= 10<sup>12</sup></code></li>
-	<li>At most <code>10<sup>4</sup></code> calls will be made to <strong>each</strong> function <code>transfer</code>, <code>deposit</code>, <code>withdraw</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How do you determine if a transaction will fail?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Simply apply the operations if the transaction is valid.
-</details>
diff --git a/problems/simplified-fractions/README.md b/problems/simplified-fractions/README.md
deleted file mode 100644
index 3b5c60dc4..000000000
--- a/problems/simplified-fractions/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../consecutive-characters "Consecutive Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../count-good-nodes-in-binary-tree "Count Good Nodes in Binary Tree")
-
-## [1447. Simplified Fractions (Medium)](https://leetcode.com/problems/simplified-fractions "最简分数")
-
-<p>Given an integer <code>n</code>, return a list of all <strong>simplified</strong> fractions between <code>0</code> and <code>1</code> (exclusive) such that the denominator is less-than-or-equal-to <code>n</code>. The fractions can be in <strong>any</strong> order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> [&quot;1/2&quot;]
-<strong>Explanation: </strong>&quot;1/2&quot; is the only unique fraction with a denominator less-than-or-equal-to 2.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> [&quot;1/2&quot;,&quot;1/3&quot;,&quot;2/3&quot;]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> [&quot;1/2&quot;,&quot;1/3&quot;,&quot;1/4&quot;,&quot;2/3&quot;,&quot;3/4&quot;]
-<strong>Explanation: </strong>&quot;2/4&quot; is not a simplified fraction because it can be simplified to &quot;1/2&quot;.</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A fraction is fully simplified if there is no integer that divides cleanly into the numerator and denominator.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In other words the greatest common divisor of the numerator and the denominator of a simplified fraction is 1.
-</details>
diff --git a/problems/simplify-path/README.md b/problems/simplify-path/README.md
deleted file mode 100644
index 3e55de4ff..000000000
--- a/problems/simplify-path/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../climbing-stairs "Climbing Stairs")
-　　　　　　　　　　　　　　　　
-[Next >](../edit-distance "Edit Distance")
-
-## [71. Simplify Path (Medium)](https://leetcode.com/problems/simplify-path "简化路径")
-
-<p>Given a string <code>path</code>, which is an <strong>absolute path</strong> (starting with a slash <code>&#39;/&#39;</code>) to a file or directory in a Unix-style file system, convert it to the simplified <strong>canonical path</strong>.</p>
-
-<p>In a Unix-style file system, a period <code>&#39;.&#39;</code> refers to the current directory, a double period <code>&#39;..&#39;</code> refers to the directory up a level, and any multiple consecutive slashes (i.e. <code>&#39;//&#39;</code>) are treated as a single slash <code>&#39;/&#39;</code>. For this problem, any other format of periods such as <code>&#39;...&#39;</code> are treated as file/directory names.</p>
-
-<p>The <strong>canonical path</strong> should have the following format:</p>
-
-<ul>
-	<li>The path starts with a single slash <code>&#39;/&#39;</code>.</li>
-	<li>Any two directories are separated by a single slash <code>&#39;/&#39;</code>.</li>
-	<li>The path does not end with a trailing <code>&#39;/&#39;</code>.</li>
-	<li>The path only contains the directories on the path from the root directory to the target file or directory (i.e., no period <code>&#39;.&#39;</code> or double period <code>&#39;..&#39;</code>)</li>
-</ul>
-
-<p>Return <em>the simplified <strong>canonical path</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> path = &quot;/home/&quot;
-<strong>Output:</strong> &quot;/home&quot;
-<strong>Explanation:</strong> Note that there is no trailing slash after the last directory name.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> path = &quot;/../&quot;
-<strong>Output:</strong> &quot;/&quot;
-<strong>Explanation:</strong> Going one level up from the root directory is a no-op, as the root level is the highest level you can go.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> path = &quot;/home//foo/&quot;
-<strong>Output:</strong> &quot;/home/foo&quot;
-<strong>Explanation:</strong> In the canonical path, multiple consecutive slashes are replaced by a single one.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= path.length &lt;= 3000</code></li>
-	<li><code>path</code> consists of English letters, digits, period <code>&#39;.&#39;</code>, slash <code>&#39;/&#39;</code> or <code>&#39;_&#39;</code>.</li>
-	<li><code>path</code> is a valid absolute Unix path.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
diff --git a/problems/simplify-path/simplify_path.go b/problems/simplify-path/simplify_path.go
deleted file mode 100644
index 085dcd303..000000000
--- a/problems/simplify-path/simplify_path.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem71
-
-import "path/filepath"
-
-func simplifyPath(path string) string {
-	return filepath.Clean(path)
-}
diff --git a/problems/simplify-path/simplify_path_test.go b/problems/simplify-path/simplify_path_test.go
deleted file mode 100644
index 3e3585734..000000000
--- a/problems/simplify-path/simplify_path_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem71
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestSimplifyPath(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "/home/",
-			want: "/home",
-		},
-		{
-			in:   "/../",
-			want: "/",
-		},
-		{
-			in:   "/home//foo/",
-			want: "/home/foo",
-		},
-		{
-			in:   "/a/./b/../../c/",
-			want: "/c",
-		},
-		{
-			in:   "/a/../../b/../c//.//",
-			want: "/c",
-		},
-		{
-			in:   "/a//b////c/d//././/..",
-			want: "/a/b/c",
-		},
-	}
-	for _, tt := range tests {
-		got := simplifyPath(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/single-element-in-a-sorted-array/README.md b/problems/single-element-in-a-sorted-array/README.md
deleted file mode 100644
index 1a2a0ca96..000000000
--- a/problems/single-element-in-a-sorted-array/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-time-difference "Minimum Time Difference")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-string-ii "Reverse String II")
-
-## [540. Single Element in a Sorted Array (Medium)](https://leetcode.com/problems/single-element-in-a-sorted-array "有序数组中的单一元素")
-
-<p>You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once.</p>
-
-<p>Return <em>the single element that appears only once</em>.</p>
-
-<p>Your solution must run in <code>O(log n)</code> time and <code>O(1)</code> space.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1,2,3,3,4,4,8,8]
-<strong>Output:</strong> 2
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [3,3,7,7,10,11,11]
-<strong>Output:</strong> 10
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
diff --git a/problems/single-element-in-a-sorted-array/single_element_in_a_sorted_array.go b/problems/single-element-in-a-sorted-array/single_element_in_a_sorted_array.go
deleted file mode 100644
index abf39daa1..000000000
--- a/problems/single-element-in-a-sorted-array/single_element_in_a_sorted_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem540
diff --git a/problems/single-element-in-a-sorted-array/single_element_in_a_sorted_array_test.go b/problems/single-element-in-a-sorted-array/single_element_in_a_sorted_array_test.go
deleted file mode 100644
index abf39daa1..000000000
--- a/problems/single-element-in-a-sorted-array/single_element_in_a_sorted_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem540
diff --git a/problems/single-number-ii/README.md b/problems/single-number-ii/README.md
deleted file mode 100644
index 61038fb11..000000000
--- a/problems/single-number-ii/README.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../single-number "Single Number")
-　　　　　　　　　　　　　　　　
-[Next >](../copy-list-with-random-pointer "Copy List with Random Pointer")
-
-## [137. Single Number II (Medium)](https://leetcode.com/problems/single-number-ii "只出现一次的数字 II")
-
-<p>Given an integer array <code>nums</code> where&nbsp;every element appears <strong>three times</strong> except for one, which appears <strong>exactly once</strong>. <em>Find the single element and return it</em>.</p>
-
-<p>You must&nbsp;implement a solution with a linear runtime complexity and use&nbsp;only constant&nbsp;extra space.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [2,2,3,2]
-<strong>Output:</strong> 3
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [0,1,0,1,0,1,99]
-<strong>Output:</strong> 99
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li>Each element in <code>nums</code> appears exactly <strong>three times</strong> except for one element which appears <strong>once</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Single Number](../single-number) (Easy)
-  1. [Single Number III](../single-number-iii) (Medium)
diff --git a/problems/single-number-ii/single_number_ii.go b/problems/single-number-ii/single_number_ii.go
deleted file mode 100644
index 768abe746..000000000
--- a/problems/single-number-ii/single_number_ii.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem137
-
-func singleNumber(nums []int) int {
-	ones, twos := 0, 0
-	for _, n := range nums {
-		ones = (ones ^ n) & ^twos
-		twos = (twos ^ n) & ^ones
-	}
-	return ones
-}
diff --git a/problems/single-number-ii/single_number_ii_test.go b/problems/single-number-ii/single_number_ii_test.go
deleted file mode 100644
index 887fd0deb..000000000
--- a/problems/single-number-ii/single_number_ii_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem137
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestSingleNumber(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{2, 2, 3, 2},
-			want: 3,
-		},
-		{
-			in:   []int{0, 1, 0, 1, 0, 1, 99},
-			want: 99,
-		},
-	}
-	for _, tt := range tests {
-		got := singleNumber(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/single-number-iii/README.md b/problems/single-number-iii/README.md
deleted file mode 100644
index e7daefd72..000000000
--- a/problems/single-number-iii/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../3sum-smaller "3Sum Smaller")
-　　　　　　　　　　　　　　　　
-[Next >](../graph-valid-tree "Graph Valid Tree")
-
-## [260. Single Number III (Medium)](https://leetcode.com/problems/single-number-iii "只出现一次的数字 III")
-
-<p>Given an integer array <code>nums</code>, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once. You can return the answer in <strong>any order</strong>.</p>
-
-<p>You must write an&nbsp;algorithm that runs in linear runtime complexity and uses&nbsp;only constant extra space.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1,3,2,5]
-<strong>Output:</strong> [3,5]
-<strong>Explanation: </strong> [5, 3] is also a valid answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,0]
-<strong>Output:</strong> [-1,0]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1]
-<strong>Output:</strong> [1,0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li>Each integer in <code>nums</code> will appear twice, only two integers will appear once.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Single Number](../single-number) (Easy)
-  1. [Single Number II](../single-number-ii) (Medium)
diff --git a/problems/single-number-iii/single_number_iii.go b/problems/single-number-iii/single_number_iii.go
deleted file mode 100644
index 39a9a2ab6..000000000
--- a/problems/single-number-iii/single_number_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem260
diff --git a/problems/single-number-iii/single_number_iii_test.go b/problems/single-number-iii/single_number_iii_test.go
deleted file mode 100644
index 39a9a2ab6..000000000
--- a/problems/single-number-iii/single_number_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem260
diff --git a/problems/single-number/README.md b/problems/single-number/README.md
deleted file mode 100644
index 29a154736..000000000
--- a/problems/single-number/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../candy "Candy")
-　　　　　　　　　　　　　　　　
-[Next >](../single-number-ii "Single Number II")
-
-## [136. Single Number (Easy)](https://leetcode.com/problems/single-number "只出现一次的数字")
-
-<p>Given a <strong>non-empty</strong>&nbsp;array of integers <code>nums</code>, every element appears <em>twice</em> except for one. Find that single one.</p>
-
-<p>You must&nbsp;implement a solution with a linear runtime complexity and use&nbsp;only constant&nbsp;extra space.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [2,2,1]
-<strong>Output:</strong> 1
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [4,1,2,1,2]
-<strong>Output:</strong> 4
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [1]
-<strong>Output:</strong> 1
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-3 * 10<sup>4</sup> &lt;= nums[i] &lt;= 3 * 10<sup>4</sup></code></li>
-	<li>Each element in the array appears twice except for one element which appears only once.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Single Number II](../single-number-ii) (Medium)
-  1. [Single Number III](../single-number-iii) (Medium)
-  1. [Missing Number](../missing-number) (Easy)
-  1. [Find the Duplicate Number](../find-the-duplicate-number) (Medium)
-  1. [Find the Difference](../find-the-difference) (Easy)
diff --git a/problems/single-number/single_number.go b/problems/single-number/single_number.go
deleted file mode 100644
index b5bb309c6..000000000
--- a/problems/single-number/single_number.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package problem136
-
-func singleNumber(nums []int) int {
-	n := 0
-	for _, v := range nums {
-		n ^= v
-	}
-	return n
-}
diff --git a/problems/single-number/single_number_test.go b/problems/single-number/single_number_test.go
deleted file mode 100644
index 559e0d9b7..000000000
--- a/problems/single-number/single_number_test.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package problem136
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestSingleNumber(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{2, 2, 1},
-			want: 1,
-		},
-		{
-			in:   []int{4, 1, 2, 1, 2},
-			want: 4,
-		},
-		{
-			in:   []int{1, 2, 1, 2, 3},
-			want: 3,
-		},
-	}
-
-	for _, tt := range tests {
-		got := singleNumber(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/single-row-keyboard/README.md b/problems/single-row-keyboard/README.md
deleted file mode 100644
index 37330813a..000000000
--- a/problems/single-row-keyboard/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../product-price-at-a-given-date "Product Price at a Given Date")
-　　　　　　　　　　　　　　　　
-[Next >](../design-file-system "Design File System")
-
-## [1165. Single-Row Keyboard (Easy)](https://leetcode.com/problems/single-row-keyboard "单行键盘")
-
-<p>There is a special keyboard with <strong>all keys in a single row</strong>.</p>
-
-<p>Given a string <code>keyboard</code> of length 26 indicating the layout of the keyboard (indexed from 0 to&nbsp;25), initially your finger is at index 0. To type a character, you have to move your finger to the index of the desired character. The time taken to move your finger from index <code>i</code> to index <code>j</code> is <code>|i - j|</code>.</p>
-
-<p>You want to type a string <code>word</code>. Write a function to calculate how much time it takes to type it with one finger.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> keyboard = &quot;abcdefghijklmnopqrstuvwxyz&quot;, word = &quot;cba&quot;
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>The index moves from 0 to 2 to write &#39;c&#39; then to 1 to write &#39;b&#39; then to 0 again to write &#39;a&#39;.
-Total time = 2 + 1 + 1 = 4. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> keyboard = &quot;pqrstuvwxyzabcdefghijklmno&quot;, word = &quot;leetcode&quot;
-<strong>Output:</strong> 73
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>keyboard.length == 26</code></li>
-	<li><code><font face="monospace">keyboard</font></code> contains each&nbsp;English lowercase letter&nbsp;exactly once in some order.</li>
-	<li><code>1 &lt;= word.length &lt;= 10^4</code></li>
-	<li><code>word[i]</code>&nbsp;is an English lowercase letter.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can be the problem divided in parts, so solving each part and sum their solutions it should return the answer? Yes, you only need to divide the problem in finger jumps.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In each finger jump you need to move your finger from one character to another, you need to know its index.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Map each character to it's index.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use a hash table to do that.
-</details>
diff --git a/problems/single-threaded-cpu/README.md b/problems/single-threaded-cpu/README.md
deleted file mode 100644
index 4b61ed447..000000000
--- a/problems/single-threaded-cpu/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-ice-cream-bars "Maximum Ice Cream Bars")
-　　　　　　　　　　　　　　　　
-[Next >](../find-xor-sum-of-all-pairs-bitwise-and "Find XOR Sum of All Pairs Bitwise AND")
-
-## [1834. Single-Threaded CPU (Medium)](https://leetcode.com/problems/single-threaded-cpu "单线程 CPU")
-
-<p>You are given <code>n</code>​​​​​​ tasks labeled from <code>0</code> to <code>n - 1</code> represented by a 2D integer array <code>tasks</code>, where <code>tasks[i] = [enqueueTime<sub>i</sub>, processingTime<sub>i</sub>]</code> means that the <code>i<sup>​​​​​​th</sup></code>​​​​ task will be available to process at <code>enqueueTime<sub>i</sub></code> and will take <code>processingTime<sub>i</sub></code><sub> </sub>to finish processing.</p>
-
-<p>You have a single-threaded CPU that can process <strong>at most one</strong> task at a time and will act in the following way:</p>
-
-<ul>
-	<li>If the CPU is idle and there are no available tasks to process, the CPU remains idle.</li>
-	<li>If the CPU is idle and there are available tasks, the CPU will choose the one with the <strong>shortest processing time</strong>. If multiple tasks have the same shortest processing time, it will choose the task with the smallest index.</li>
-	<li>Once a task is started, the CPU will <strong>process the entire task</strong> without stopping.</li>
-	<li>The CPU can finish a task then start a new one instantly.</li>
-</ul>
-
-<p>Return <em>the order in which the CPU will process the tasks.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [[1,2],[2,4],[3,2],[4,1]]
-<strong>Output:</strong> [0,2,3,1]
-<strong>Explanation: </strong>The events go as follows: 
-- At time = 1, task 0 is available to process. Available tasks = {0}.
-- Also at time = 1, the idle CPU starts processing task 0. Available tasks = {}.
-- At time = 2, task 1 is available to process. Available tasks = {1}.
-- At time = 3, task 2 is available to process. Available tasks = {1, 2}.
-- Also at time = 3, the CPU finishes task 0 and starts processing task 2 as it is the shortest. Available tasks = {1}.
-- At time = 4, task 3 is available to process. Available tasks = {1, 3}.
-- At time = 5, the CPU finishes task 2 and starts processing task 3 as it is the shortest. Available tasks = {1}.
-- At time = 6, the CPU finishes task 3 and starts processing task 1. Available tasks = {}.
-- At time = 10, the CPU finishes task 1 and becomes idle.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [[7,10],[7,12],[7,5],[7,4],[7,2]]
-<strong>Output:</strong> [4,3,2,0,1]
-<strong>Explanation</strong><strong>: </strong>The events go as follows:
-- At time = 7, all the tasks become available. Available tasks = {0,1,2,3,4}.
-- Also at time = 7, the idle CPU starts processing task 4. Available tasks = {0,1,2,3}.
-- At time = 9, the CPU finishes task 4 and starts processing task 3. Available tasks = {0,1,2}.
-- At time = 13, the CPU finishes task 3 and starts processing task 2. Available tasks = {0,1}.
-- At time = 18, the CPU finishes task 2 and starts processing task 0. Available tasks = {1}.
-- At time = 28, the CPU finishes task 0 and starts processing task 1. Available tasks = {}.
-- At time = 40, the CPU finishes task 1 and becomes idle.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>tasks.length == n</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= enqueueTime<sub>i</sub>, processingTime<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-To simulate the problem we first need to note that if at any point in time there are no enqueued tasks we need to wait to the smallest enqueue time of a non-processed element
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We need a data structure like a min-heap to support choosing the task with the smallest processing time from all the enqueued tasks
-</details>
diff --git a/problems/sliding-puzzle/README.md b/problems/sliding-puzzle/README.md
deleted file mode 100644
index 6b0fb4589..000000000
--- a/problems/sliding-puzzle/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../basic-calculator-iii "Basic Calculator III")
-　　　　　　　　　　　　　　　　
-[Next >](../minimize-max-distance-to-gas-station "Minimize Max Distance to Gas Station")
-
-## [773. Sliding Puzzle (Hard)](https://leetcode.com/problems/sliding-puzzle "滑动谜题")
-
-<p>On an <code>2 x 3</code> board, there are five tiles labeled from <code>1</code> to <code>5</code>, and an empty square represented by <code>0</code>. A <strong>move</strong> consists of choosing <code>0</code> and a 4-directionally adjacent number and swapping it.</p>
-
-<p>The state of the board is solved if and only if the board is <code>[[1,2,3],[4,5,0]]</code>.</p>
-
-<p>Given the puzzle board <code>board</code>, return <em>the least number of moves required so that the state of the board is solved</em>. If it is impossible for the state of the board to be solved, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/slide1-grid.jpg" style="width: 244px; height: 165px;" />
-<pre>
-<strong>Input:</strong> board = [[1,2,3],[4,0,5]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Swap the 0 and the 5 in one move.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/slide2-grid.jpg" style="width: 244px; height: 165px;" />
-<pre>
-<strong>Input:</strong> board = [[1,2,3],[5,4,0]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> No number of moves will make the board solved.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/slide3-grid.jpg" style="width: 244px; height: 165px;" />
-<pre>
-<strong>Input:</strong> board = [[4,1,2],[5,0,3]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> 5 is the smallest number of moves that solves the board.
-An example path:
-After move 0: [[4,1,2],[5,0,3]]
-After move 1: [[4,1,2],[0,5,3]]
-After move 2: [[0,1,2],[4,5,3]]
-After move 3: [[1,0,2],[4,5,3]]
-After move 4: [[1,2,0],[4,5,3]]
-After move 5: [[1,2,3],[4,5,0]]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/slide4-grid.jpg" style="width: 244px; height: 165px;" />
-<pre>
-<strong>Input:</strong> board = [[3,2,4],[1,5,0]]
-<strong>Output:</strong> 14
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>board.length == 2</code></li>
-	<li><code>board[i].length == 3</code></li>
-	<li><code>0 &lt;= board[i][j] &lt;= 5</code></li>
-	<li>Each value <code>board[i][j]</code> is <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Perform a breadth-first-search, where the nodes are the puzzle boards and edges are if two puzzle boards can be transformed into one another with one move.
-</details>
diff --git a/problems/sliding-puzzle/sliding_puzzle.go b/problems/sliding-puzzle/sliding_puzzle.go
deleted file mode 100644
index cee74bbaa..000000000
--- a/problems/sliding-puzzle/sliding_puzzle.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem773
diff --git a/problems/sliding-puzzle/sliding_puzzle_test.go b/problems/sliding-puzzle/sliding_puzzle_test.go
deleted file mode 100644
index cee74bbaa..000000000
--- a/problems/sliding-puzzle/sliding_puzzle_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem773
diff --git a/problems/sliding-window-maximum/README.md b/problems/sliding-window-maximum/README.md
deleted file mode 100644
index 9ba626b8d..000000000
--- a/problems/sliding-window-maximum/README.md
+++ /dev/null
@@ -1,100 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../product-of-array-except-self "Product of Array Except Self")
-　　　　　　　　　　　　　　　　
-[Next >](../search-a-2d-matrix-ii "Search a 2D Matrix II")
-
-## [239. Sliding Window Maximum (Hard)](https://leetcode.com/problems/sliding-window-maximum "滑动窗口最大值")
-
-<p>You are given an array of integers&nbsp;<code>nums</code>, there is a sliding window of size <code>k</code> which is moving from the very left of the array to the very right. You can only see the <code>k</code> numbers in the window. Each time the sliding window moves right by one position.</p>
-
-<p>Return <em>the max sliding window</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,-1,-3,5,3,6,7], k = 3
-<strong>Output:</strong> [3,3,5,5,6,7]
-<strong>Explanation:</strong> 
-Window position                Max
----------------               -----
-[1  3  -1] -3  5  3  6  7       <strong>3</strong>
- 1 [3  -1  -3] 5  3  6  7       <strong>3</strong>
- 1  3 [-1  -3  5] 3  6  7      <strong> 5</strong>
- 1  3  -1 [-3  5  3] 6  7       <strong>5</strong>
- 1  3  -1  -3 [5  3  6] 7       <strong>6</strong>
- 1  3  -1  -3  5 [3  6  7]      <strong>7</strong>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1], k = 1
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,-1], k = 1
-<strong>Output:</strong> [1,-1]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [9,11], k = 2
-<strong>Output:</strong> [11]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,-2], k = 2
-<strong>Output:</strong> [4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= k &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Monotonic Queue](../../tag/monotonic-queue/README.md)]
-
-### Similar Questions
-  1. [Minimum Window Substring](../minimum-window-substring) (Hard)
-  1. [Min Stack](../min-stack) (Easy)
-  1. [Longest Substring with At Most Two Distinct Characters](../longest-substring-with-at-most-two-distinct-characters) (Medium)
-  1. [Paint House II](../paint-house-ii) (Hard)
-  1. [Jump Game VI](../jump-game-vi) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How about using a data structure such as deque (double-ended queue)?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The queue size need not be the same as the window’s size.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Remove redundant elements and the queue should store only elements that need to be considered.
-</details>
diff --git a/problems/sliding-window-maximum/sliding_window_maximum.go b/problems/sliding-window-maximum/sliding_window_maximum.go
deleted file mode 100644
index 9fdef387a..000000000
--- a/problems/sliding-window-maximum/sliding_window_maximum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem239
diff --git a/problems/sliding-window-maximum/sliding_window_maximum_test.go b/problems/sliding-window-maximum/sliding_window_maximum_test.go
deleted file mode 100644
index 9fdef387a..000000000
--- a/problems/sliding-window-maximum/sliding_window_maximum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem239
diff --git a/problems/sliding-window-median/README.md b/problems/sliding-window-median/README.md
deleted file mode 100644
index af143bcb9..000000000
--- a/problems/sliding-window-median/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-palindrome-product "Largest Palindrome Product")
-　　　　　　　　　　　　　　　　
-[Next >](../magical-string "Magical String")
-
-## [480. Sliding Window Median (Hard)](https://leetcode.com/problems/sliding-window-median "滑动窗口中位数")
-
-<p>The <strong>median</strong> is the middle value in an ordered integer list. If the size of the list is even, there is no middle value. So the median is the mean of the two middle values.</p>
-
-<ul>
-	<li>For examples, if <code>arr = [2,<u>3</u>,4]</code>, the median is <code>3</code>.</li>
-	<li>For examples, if <code>arr = [1,<u>2,3</u>,4]</code>, the median is <code>(2 + 3) / 2 = 2.5</code>.</li>
-</ul>
-
-<p>You are given an integer array <code>nums</code> and an integer <code>k</code>. There is a sliding window of size <code>k</code> which is moving from the very left of the array to the very right. You can only see the <code>k</code> numbers in the window. Each time the sliding window moves right by one position.</p>
-
-<p>Return <em>the median array for each window in the original array</em>. Answers within <code>10<sup>-5</sup></code> of the actual value will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,-1,-3,5,3,6,7], k = 3
-<strong>Output:</strong> [1.00000,-1.00000,-1.00000,3.00000,5.00000,6.00000]
-<strong>Explanation:</strong> 
-Window position                Median
----------------                -----
-[<strong>1  3  -1</strong>] -3  5  3  6  7        1
- 1 [<strong>3  -1  -3</strong>] 5  3  6  7       -1
- 1  3 [<strong>-1  -3  5</strong>] 3  6  7       -1
- 1  3  -1 [<strong>-3  5  3</strong>] 6  7        3
- 1  3  -1  -3 [<strong>5  3  6</strong>] 7        5
- 1  3  -1  -3  5 [<strong>3  6  7</strong>]       6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,2,3,1,4,2], k = 3
-<strong>Output:</strong> [2.00000,3.00000,3.00000,3.00000,2.00000,3.00000,2.00000]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Find Median from Data Stream](../find-median-from-data-stream) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The simplest of solutions comes from the basic idea of finding the median given a set of numbers. We know that by definition, a median is the center element (or an average of the two center elements). Given an unsorted list of numbers, how do we find the median element? If you know the answer to this question, can we extend this idea to every sliding window that we come across in the array?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Is there a better way to do what we are doing in the above hint? Don't you think there is duplication of calculation being done there? Is there some sort of optimization that we can do to achieve the same result? This approach is merely a modification of the basic approach except that it simply reduces duplication of calculations once done.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The third line of thought is also based on this same idea but achieving the result in a different way. We obviously need the window to be sorted for us to be able to find the median. Is there a data-structure out there that we can use (in one or more quantities) to obtain the median element extremely fast, say O(1) time while having the ability to perform the other operations fairly efficiently as well?
-</details>
diff --git a/problems/sliding-window-median/sliding_window_median.go b/problems/sliding-window-median/sliding_window_median.go
deleted file mode 100644
index fdb8acca6..000000000
--- a/problems/sliding-window-median/sliding_window_median.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem480
diff --git a/problems/sliding-window-median/sliding_window_median_test.go b/problems/sliding-window-median/sliding_window_median_test.go
deleted file mode 100644
index fdb8acca6..000000000
--- a/problems/sliding-window-median/sliding_window_median_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem480
diff --git a/problems/slowest-key/README.md b/problems/slowest-key/README.md
deleted file mode 100644
index 96e1088ff..000000000
--- a/problems/slowest-key/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-an-expression-tree-with-evaluate-function "Design an Expression Tree With Evaluate Function")
-　　　　　　　　　　　　　　　　
-[Next >](../arithmetic-subarrays "Arithmetic Subarrays")
-
-## [1629. Slowest Key (Easy)](https://leetcode.com/problems/slowest-key "按键持续时间最长的键")
-
-<p>A newly designed keypad was tested, where a tester pressed a sequence of <code>n</code> keys, one at a time.</p>
-
-<p>You are given a string <code>keysPressed</code> of length <code>n</code>, where <code>keysPressed[i]</code> was the <code>i<sup>th</sup></code> key pressed in the testing sequence, and a sorted list <code>releaseTimes</code>, where <code>releaseTimes[i]</code> was the time the <code>i<sup>th</sup></code> key was released. Both arrays are <strong>0-indexed</strong>. The <code>0<sup>th</sup></code> key was pressed at the time <code>0</code>,&nbsp;and every subsequent key was pressed at the <strong>exact</strong> time the previous key was released.</p>
-
-<p>The tester wants to know the key of the keypress that had the <strong>longest duration</strong>. The <code>i<sup>th</sup></code><sup> </sup>keypress had a <strong>duration</strong> of <code>releaseTimes[i] - releaseTimes[i - 1]</code>, and the <code>0<sup>th</sup></code> keypress had a duration of <code>releaseTimes[0]</code>.</p>
-
-<p>Note that the same key could have been pressed multiple times during the test, and these multiple presses of the same key <strong>may not</strong> have had the same <strong>duration</strong>.</p>
-
-<p><em>Return the key of the keypress that had the <strong>longest duration</strong>. If there are multiple such keypresses, return the lexicographically largest key of the keypresses.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> releaseTimes = [9,29,49,50], keysPressed = &quot;cbcd&quot;
-<strong>Output:</strong> &quot;c&quot;
-<strong>Explanation:</strong> The keypresses were as follows:
-Keypress for &#39;c&#39; had a duration of 9 (pressed at time 0 and released at time 9).
-Keypress for &#39;b&#39; had a duration of 29 - 9 = 20 (pressed at time 9 right after the release of the previous character and released at time 29).
-Keypress for &#39;c&#39; had a duration of 49 - 29 = 20 (pressed at time 29 right after the release of the previous character and released at time 49).
-Keypress for &#39;d&#39; had a duration of 50 - 49 = 1 (pressed at time 49 right after the release of the previous character and released at time 50).
-The longest of these was the keypress for &#39;b&#39; and the second keypress for &#39;c&#39;, both with duration 20.
-&#39;c&#39; is lexicographically larger than &#39;b&#39;, so the answer is &#39;c&#39;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> releaseTimes = [12,23,36,46,62], keysPressed = &quot;spuda&quot;
-<strong>Output:</strong> &quot;a&quot;
-<strong>Explanation:</strong> The keypresses were as follows:
-Keypress for &#39;s&#39; had a duration of 12.
-Keypress for &#39;p&#39; had a duration of 23 - 12 = 11.
-Keypress for &#39;u&#39; had a duration of 36 - 23 = 13.
-Keypress for &#39;d&#39; had a duration of 46 - 36 = 10.
-Keypress for &#39;a&#39; had a duration of 62 - 46 = 16.
-The longest of these was the keypress for &#39;a&#39; with duration 16.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>releaseTimes.length == n</code></li>
-	<li><code>keysPressed.length == n</code></li>
-	<li><code>2 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= releaseTimes[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>releaseTimes[i] &lt; releaseTimes[i+1]</code></li>
-	<li><code>keysPressed</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Get for each press its key and amount of time taken.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Iterate on the presses, maintaining the answer so far.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The current press will change the answer if and only if its amount of time taken is longer than that of the previous answer, or they are equal but the key is larger than that of the previous answer.
-</details>
diff --git a/problems/smallest-common-region/README.md b/problems/smallest-common-region/README.md
deleted file mode 100644
index 85f65043f..000000000
--- a/problems/smallest-common-region/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../encode-number "Encode Number")
-　　　　　　　　　　　　　　　　
-[Next >](../synonymous-sentences "Synonymous Sentences")
-
-## [1257. Smallest Common Region (Medium)](https://leetcode.com/problems/smallest-common-region "最小公共区域")
-
-<p>You are given some lists of <code>regions</code>&nbsp;where the first region of each list includes all other regions in that list.</p>
-
-<p>Naturally, if a region <code>X</code>&nbsp;contains another region <code>Y</code>&nbsp;then <code>X</code>&nbsp;is bigger than <code>Y</code>.</p>
-
-<p>Given two regions <code>region1</code>, <code>region2</code>, find out the <strong>smallest</strong> region that contains both of them.</p>
-
-<p>If you are given regions <code>r1</code>, <code>r2</code> and <code>r3</code> such that <code>r1</code> includes <code>r3</code>, it is guaranteed there is no <code>r2</code> such that <code>r2</code> includes <code>r3</code>.<br />
-<br />
-It&#39;s guaranteed the smallest region exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:
-</strong>regions = [[&quot;Earth&quot;,&quot;North America&quot;,&quot;South America&quot;],
-[&quot;North America&quot;,&quot;United States&quot;,&quot;Canada&quot;],
-[&quot;United States&quot;,&quot;New York&quot;,&quot;Boston&quot;],
-[&quot;Canada&quot;,&quot;Ontario&quot;,&quot;Quebec&quot;],
-[&quot;South America&quot;,&quot;Brazil&quot;]],
-region1 = &quot;Quebec&quot;,
-region2 = &quot;New York&quot;
-<strong>Output:</strong> &quot;North America&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= regions.length &lt;= 10^4</code></li>
-	<li><code>region1 != region2</code></li>
-	<li>All strings consist of English letters and spaces with at most 20 letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Lowest Common Ancestor of a Binary Search Tree](../lowest-common-ancestor-of-a-binary-search-tree) (Easy)
-  1. [Lowest Common Ancestor of a Binary Tree](../lowest-common-ancestor-of-a-binary-tree) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to model the problem as a graph problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The given graph is a tree.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The problem is reduced to finding the lowest common ancestor of two nodes in a tree.
-</details>
diff --git a/problems/smallest-good-base/README.md b/problems/smallest-good-base/README.md
deleted file mode 100644
index 99e61b3f4..000000000
--- a/problems/smallest-good-base/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../license-key-formatting "License Key Formatting")
-　　　　　　　　　　　　　　　　
-[Next >](../find-permutation "Find Permutation")
-
-## [483. Smallest Good Base (Hard)](https://leetcode.com/problems/smallest-good-base "最小好进制")
-
-<p>Given an integer <code>n</code> represented as a string, return <em>the smallest <strong>good base</strong> of</em> <code>n</code>.</p>
-
-<p>We call <code>k &gt;= 2</code> a <strong>good base</strong> of <code>n</code>, if all digits of <code>n</code> base <code>k</code> are <code>1</code>&#39;s.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;13&quot;
-<strong>Output:</strong> &quot;3&quot;
-<strong>Explanation:</strong> 13 base 3 is 111.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;4681&quot;
-<strong>Output:</strong> &quot;8&quot;
-<strong>Explanation:</strong> 4681 base 8 is 11111.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = &quot;1000000000000000000&quot;
-<strong>Output:</strong> &quot;999999999999999999&quot;
-<strong>Explanation:</strong> 1000000000000000000 base 999999999999999999 is 11.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n</code> is an integer in the range <code>[3, 10<sup>18</sup>]</code>.</li>
-	<li><code>n</code> does not contain any leading zeros.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
diff --git a/problems/smallest-good-base/smallest_good_base.go b/problems/smallest-good-base/smallest_good_base.go
deleted file mode 100644
index 34df7d619..000000000
--- a/problems/smallest-good-base/smallest_good_base.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem483
diff --git a/problems/smallest-good-base/smallest_good_base_test.go b/problems/smallest-good-base/smallest_good_base_test.go
deleted file mode 100644
index 34df7d619..000000000
--- a/problems/smallest-good-base/smallest_good_base_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem483
diff --git a/problems/smallest-greater-multiple-made-of-two-digits/README.md b/problems/smallest-greater-multiple-made-of-two-digits/README.md
deleted file mode 100644
index cd7e4bd7f..000000000
--- a/problems/smallest-greater-multiple-made-of-two-digits/README.md
+++ /dev/null
@@ -1,25 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../gcd-sort-of-an-array "GCD Sort of an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-prefix-of-word "Reverse Prefix of Word")
-
-## [1999. Smallest Greater Multiple Made of Two Digits (Medium)](https://leetcode.com/problems/smallest-greater-multiple-made-of-two-digits "最小的仅由两个数组成的倍数")
-
-
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could you generate all the different numbers comprised of only digit1 and digit2 with the constraints?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Going from least to greatest, check if the number you generated is greater than k and a multiple of k.
-</details>
diff --git a/problems/smallest-index-with-equal-value/README.md b/problems/smallest-index-with-equal-value/README.md
deleted file mode 100644
index 48843d83d..000000000
--- a/problems/smallest-index-with-equal-value/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-valid-move-combinations-on-chessboard "Number of Valid Move Combinations On Chessboard")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-minimum-and-maximum-number-of-nodes-between-critical-points "Find the Minimum and Maximum Number of Nodes Between Critical Points")
-
-## [2057. Smallest Index With Equal Value (Easy)](https://leetcode.com/problems/smallest-index-with-equal-value "值相等的最小索引")
-
-<p>Given a <strong>0-indexed</strong> integer array <code>nums</code>, return <em>the <strong>smallest</strong> index </em><code>i</code><em> of </em><code>nums</code><em> such that </em><code>i mod 10 == nums[i]</code><em>, or </em><code>-1</code><em> if such index does not exist</em>.</p>
-
-<p><code>x mod y</code> denotes the <strong>remainder</strong> when <code>x</code> is divided by <code>y</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,2]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> 
-i=0: 0 mod 10 = 0 == nums[0].
-i=1: 1 mod 10 = 1 == nums[1].
-i=2: 2 mod 10 = 2 == nums[2].
-All indices have i mod 10 == nums[i], so we return the smallest index 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,3,2,1]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-i=0: 0 mod 10 = 0 != nums[0].
-i=1: 1 mod 10 = 1 != nums[1].
-i=2: 2 mod 10 = 2 == nums[2].
-i=3: 3 mod 10 = 3 != nums[3].
-2 is the only index which has i mod 10 == nums[i].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5,6,7,8,9,0]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> No index satisfies i mod 10 == nums[i].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 9</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Starting with i=0, check the condition for each index. The first one you find to be true is the smallest index.
-</details>
diff --git a/problems/smallest-integer-divisible-by-k/README.md b/problems/smallest-integer-divisible-by-k/README.md
deleted file mode 100644
index 295bc573d..000000000
--- a/problems/smallest-integer-divisible-by-k/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../best-sightseeing-pair "Best Sightseeing Pair")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-string-with-substrings-representing-1-to-n "Binary String With Substrings Representing 1 To N")
-
-## [1015. Smallest Integer Divisible by K (Medium)](https://leetcode.com/problems/smallest-integer-divisible-by-k "可被 K 整除的最小整数")
-
-<p>Given a positive integer <code>k</code>, you need to find the <strong>length</strong> of the <strong>smallest</strong> positive integer <code>n</code> such that <code>n</code> is divisible by <code>k</code>, and <code>n</code> only contains the digit <code>1</code>.</p>
-
-<p>Return <em>the <strong>length</strong> of </em><code>n</code>. If there is no such <code>n</code>, return -1.</p>
-
-<p><strong>Note:</strong> <code>n</code> may not fit in a 64-bit signed integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 1
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The smallest answer is n = 1, which has length 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 2
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> There is no such positive integer n divisible by 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The smallest answer is n = 111, which has length 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-11111 = 1111 * 10 + 1
-We only need to store remainders modulo K.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If we never get a remainder of 0, why would that happen, and how would we know that?
-</details>
diff --git a/problems/smallest-integer-divisible-by-k/smallest_integer_divisible_by_k.go b/problems/smallest-integer-divisible-by-k/smallest_integer_divisible_by_k.go
deleted file mode 100644
index 9221f14fa..000000000
--- a/problems/smallest-integer-divisible-by-k/smallest_integer_divisible_by_k.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem1015
-
-func smallestRepunitDivByK(K int) int {
-	if K%2 == 0 || K%5 == 0 {
-		return -1
-	}
-
-	r, length := 1%K, 1
-	for r != 0 && length <= K {
-		r = (r*10 + 1) % K
-		length++
-	}
-
-	return length
-}
diff --git a/problems/smallest-k-length-subsequence-with-occurrences-of-a-letter/README.md b/problems/smallest-k-length-subsequence-with-occurrences-of-a-letter/README.md
deleted file mode 100644
index 172effb70..000000000
--- a/problems/smallest-k-length-subsequence-with-occurrences-of-a-letter/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stone-game-ix "Stone Game IX")
-　　　　　　　　　　　　　　　　
-[Next >](../count-subarrays-with-more-ones-than-zeros "Count Subarrays With More Ones Than Zeros")
-
-## [2030. Smallest K-Length Subsequence With Occurrences of a Letter (Hard)](https://leetcode.com/problems/smallest-k-length-subsequence-with-occurrences-of-a-letter "含特定字母的最小子序列")
-
-<p>You are given a string <code>s</code>, an integer <code>k</code>, a letter <code>letter</code>, and an integer <code>repetition</code>.</p>
-
-<p>Return <em>the <strong>lexicographically smallest</strong> subsequence of</em> <code>s</code><em> of length</em> <code>k</code> <em>that has the letter</em> <code>letter</code> <em>appear <strong>at least</strong></em> <code>repetition</code> <em>times</em>. The test cases are generated so that the <code>letter</code> appears in <code>s</code> <strong>at least</strong> <code>repetition</code> times.</p>
-
-<p>A <strong>subsequence</strong> is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters.</p>
-
-<p>A string <code>a</code> is <strong>lexicographically smaller</strong> than a string <code>b</code> if in the first position where <code>a</code> and <code>b</code> differ, string <code>a</code> has a letter that appears earlier in the alphabet than the corresponding letter in <code>b</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leet&quot;, k = 3, letter = &quot;e&quot;, repetition = 1
-<strong>Output:</strong> &quot;eet&quot;
-<strong>Explanation:</strong> There are four subsequences of length 3 that have the letter &#39;e&#39; appear at least 1 time:
-- &quot;lee&quot; (from &quot;<strong><u>lee</u></strong>t&quot;)
-- &quot;let&quot; (from &quot;<strong><u>le</u></strong>e<u><strong>t</strong></u>&quot;)
-- &quot;let&quot; (from &quot;<u><strong>l</strong></u>e<u><strong>et</strong></u>&quot;)
-- &quot;eet&quot; (from &quot;l<u><strong>eet</strong></u>&quot;)
-The lexicographically smallest subsequence among them is &quot;eet&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="example-2" src="https://assets.leetcode.com/uploads/2021/09/13/smallest-k-length-subsequence.png" style="width: 339px; height: 67px;" />
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;, k = 4, letter = &quot;e&quot;, repetition = 2
-<strong>Output:</strong> &quot;ecde&quot;
-<strong>Explanation:</strong> &quot;ecde&quot; is the lexicographically smallest subsequence of length 4 that has the letter &quot;e&quot; appear at least 2 times.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bb&quot;, k = 2, letter = &quot;b&quot;, repetition = 2
-<strong>Output:</strong> &quot;bb&quot;
-<strong>Explanation:</strong> &quot;bb&quot; is the only subsequence of length 2 that has the letter &quot;b&quot; appear at least 2 times.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= repetition &lt;= k &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-	<li><code>letter</code> is a lowercase English letter, and appears in <code>s</code> at least <code>repetition</code> times.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use stack. For every character to be appended, decide how many character(s) from the stack needs to get popped based on the stack length and the count of the required character.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Pop the extra characters out from the stack and return the characters in the stack (reversed).
-</details>
diff --git a/problems/smallest-missing-genetic-value-in-each-subtree/README.md b/problems/smallest-missing-genetic-value-in-each-subtree/README.md
deleted file mode 100644
index 0a4c2f101..000000000
--- a/problems/smallest-missing-genetic-value-in-each-subtree/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-product-of-the-length-of-two-palindromic-subsequences "Maximum Product of the Length of Two Palindromic Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-seniors-and-juniors-to-join-the-company "The Number of Seniors and Juniors to Join the Company")
-
-## [2003. Smallest Missing Genetic Value in Each Subtree (Hard)](https://leetcode.com/problems/smallest-missing-genetic-value-in-each-subtree "每棵子树内缺失的最小基因值")
-
-<p>There is a <strong>family tree</strong> rooted at <code>0</code> consisting of <code>n</code> nodes numbered <code>0</code> to <code>n - 1</code>. You are given a <strong>0-indexed</strong> integer array <code>parents</code>, where <code>parents[i]</code> is the parent for node <code>i</code>. Since node <code>0</code> is the <strong>root</strong>, <code>parents[0] == -1</code>.</p>
-
-<p>There are <code>10<sup>5</sup></code> genetic values, each represented by an integer in the <strong>inclusive</strong> range <code>[1, 10<sup>5</sup>]</code>. You are given a <strong>0-indexed</strong> integer array <code>nums</code>, where <code>nums[i]</code> is a <strong>distinct </strong>genetic value for node <code>i</code>.</p>
-
-<p>Return <em>an array </em><code>ans</code><em> of length </em><code>n</code><em> where </em><code>ans[i]</code><em> is</em> <em>the <strong>smallest</strong> genetic value that is <strong>missing</strong> from the subtree rooted at node</em> <code>i</code>.</p>
-
-<p>The <strong>subtree</strong> rooted at a node <code>x</code> contains node <code>x</code> and all of its <strong>descendant</strong> nodes.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/23/case-1.png" style="width: 204px; height: 167px;" />
-<pre>
-<strong>Input:</strong> parents = [-1,0,0,2], nums = [1,2,3,4]
-<strong>Output:</strong> [5,1,1,1]
-<strong>Explanation:</strong> The answer for each subtree is calculated as follows:
-- 0: The subtree contains nodes [0,1,2,3] with values [1,2,3,4]. 5 is the smallest missing value.
-- 1: The subtree contains only node 1 with value 2. 1 is the smallest missing value.
-- 2: The subtree contains nodes [2,3] with values [3,4]. 1 is the smallest missing value.
-- 3: The subtree contains only node 3 with value 4. 1 is the smallest missing value.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/23/case-2.png" style="width: 247px; height: 168px;" />
-<pre>
-<strong>Input:</strong> parents = [-1,0,1,0,3,3], nums = [5,4,6,2,1,3]
-<strong>Output:</strong> [7,1,1,4,2,1]
-<strong>Explanation:</strong> The answer for each subtree is calculated as follows:
-- 0: The subtree contains nodes [0,1,2,3,4,5] with values [5,4,6,2,1,3]. 7 is the smallest missing value.
-- 1: The subtree contains nodes [1,2] with values [4,6]. 1 is the smallest missing value.
-- 2: The subtree contains only node 2 with value 6. 1 is the smallest missing value.
-- 3: The subtree contains nodes [3,4,5] with values [2,1,3]. 4 is the smallest missing value.
-- 4: The subtree contains only node 4 with value 1. 2 is the smallest missing value.
-- 5: The subtree contains only node 5 with value 3. 1 is the smallest missing value.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> parents = [-1,2,3,0,2,4,1], nums = [2,3,4,5,6,7,8]
-<strong>Output:</strong> [1,1,1,1,1,1,1]
-<strong>Explanation:</strong> The value 1 is missing from all the subtrees.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == parents.length == nums.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= parents[i] &lt;= n - 1</code> for <code>i != 0</code></li>
-	<li><code>parents[0] == -1</code></li>
-	<li><code>parents</code> represents a valid tree.</li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-	<li>Each <code>nums[i]</code> is distinct.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If the subtree doesn't contain 1, then the missing value will always be 1.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What data structure allows us to dynamically update the values that are currently not present?
-</details>
diff --git a/problems/smallest-range-covering-elements-from-k-lists/README.md b/problems/smallest-range-covering-elements-from-k-lists/README.md
deleted file mode 100644
index 7738b24d9..000000000
--- a/problems/smallest-range-covering-elements-from-k-lists/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-excel-sum-formula "Design Excel Sum Formula")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-square-numbers "Sum of Square Numbers")
-
-## [632. Smallest Range Covering Elements from K Lists (Hard)](https://leetcode.com/problems/smallest-range-covering-elements-from-k-lists "最小区间")
-
-<p>You have <code>k</code> lists of sorted integers in <strong>non-decreasing&nbsp;order</strong>. Find the <b>smallest</b> range that includes at least one number from each of the <code>k</code> lists.</p>
-
-<p>We define the range <code>[a, b]</code> is smaller than range <code>[c, d]</code> if <code>b - a &lt; d - c</code> <strong>or</strong> <code>a &lt; c</code> if <code>b - a == d - c</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [[4,10,15,24,26],[0,9,12,20],[5,18,22,30]]
-<strong>Output:</strong> [20,24]
-<strong>Explanation: </strong>
-List 1: [4, 10, 15, 24,26], 24 is in range [20,24].
-List 2: [0, 9, 12, 20], 20 is in range [20,24].
-List 3: [5, 18, 22, 30], 22 is in range [20,24].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [[1,2,3],[1,2,3],[1,2,3]]
-<strong>Output:</strong> [1,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>nums.length == k</code></li>
-	<li><code>1 &lt;= k &lt;= 3500</code></li>
-	<li><code>1 &lt;= nums[i].length &lt;= 50</code></li>
-	<li><code>-10<sup>5</sup> &lt;= nums[i][j] &lt;= 10<sup>5</sup></code></li>
-	<li><code>nums[i]</code>&nbsp;is sorted in <strong>non-decreasing</strong> order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Minimum Window Substring](../minimum-window-substring) (Hard)
diff --git a/problems/smallest-range-i/README.md b/problems/smallest-range-i/README.md
deleted file mode 100644
index 124e529b4..000000000
--- a/problems/smallest-range-i/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-subarray-minimums "Sum of Subarray Minimums")
-　　　　　　　　　　　　　　　　
-[Next >](../snakes-and-ladders "Snakes and Ladders")
-
-## [908. Smallest Range I (Easy)](https://leetcode.com/problems/smallest-range-i "最小差值 I")
-
-<p>You are given an integer array <code>nums</code> and an integer <code>k</code>.</p>
-
-<p>In one operation, you can choose any index <code>i</code> where <code>0 &lt;= i &lt; nums.length</code> and change <code>nums[i]</code> to <code>nums[i] + x</code> where <code>x</code> is an integer from the range <code>[-k, k]</code>. You can apply this operation <strong>at most once</strong> for each index <code>i</code>.</p>
-
-<p>The <strong>score</strong> of <code>nums</code> is the difference between the maximum and minimum elements in <code>nums</code>.</p>
-
-<p>Return <em>the minimum <strong>score</strong> of </em><code>nums</code><em> after applying the mentioned operation at most once for each index in it</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1], k = 0
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The score is max(nums) - min(nums) = 1 - 1 = 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,10], k = 2
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Change nums to be [2, 8]. The score is max(nums) - min(nums) = 8 - 2 = 6.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,6], k = 3
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Change nums to be [4, 4, 4]. The score is max(nums) - min(nums) = 4 - 4 = 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= k &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/smallest-range-i/smallest_range_i.go b/problems/smallest-range-i/smallest_range_i.go
deleted file mode 100644
index 22631dba4..000000000
--- a/problems/smallest-range-i/smallest_range_i.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem908
-
-func smallestRangeI(A []int, K int) int {
-	min, max := A[0], A[0]
-	for _, v := range A {
-		if v < min {
-			min = v
-		} else if v > max {
-			max = v
-		}
-	}
-	ans := max - min - 2*K
-	if ans < 0 {
-		return 0
-	}
-	return ans
-}
diff --git a/problems/smallest-range-i/smallest_range_i_test.go b/problems/smallest-range-i/smallest_range_i_test.go
deleted file mode 100644
index 69fb1faf8..000000000
--- a/problems/smallest-range-i/smallest_range_i_test.go
+++ /dev/null
@@ -1,45 +0,0 @@
-package problem908
-
-import "testing"
-
-type testType struct {
-	in   []int
-	k    int
-	want int
-}
-
-func TestSmallestRangeI(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1},
-			k:    0,
-			want: 0,
-		},
-		{
-			in:   []int{0, 10},
-			k:    2,
-			want: 6,
-		},
-		{
-			in:   []int{1, 3, 6},
-			k:    3,
-			want: 0,
-		},
-		{
-			in:   []int{1, 3, 5, 7, 9},
-			k:    1,
-			want: 6,
-		},
-		{
-			in:   []int{18, 16, 12, 7, 9, 3, 5},
-			k:    6,
-			want: 3,
-		},
-	}
-	for _, tt := range tests {
-		got := smallestRangeI(tt.in, tt.k)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/smallest-range-ii/README.md b/problems/smallest-range-ii/README.md
deleted file mode 100644
index 8dbed5def..000000000
--- a/problems/smallest-range-ii/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../snakes-and-ladders "Snakes and Ladders")
-　　　　　　　　　　　　　　　　
-[Next >](../online-election "Online Election")
-
-## [910. Smallest Range II (Medium)](https://leetcode.com/problems/smallest-range-ii "最小差值 II")
-
-<p>You are given an integer array <code>nums</code> and an integer <code>k</code>.</p>
-
-<p>For each index <code>i</code> where <code>0 &lt;= i &lt; nums.length</code>, change <code>nums[i]</code> to be either <code>nums[i] + k</code> or <code>nums[i] - k</code>.</p>
-
-<p>The <strong>score</strong> of <code>nums</code> is the difference between the maximum and minimum elements in <code>nums</code>.</p>
-
-<p>Return <em>the minimum <strong>score</strong> of </em><code>nums</code><em> after changing the values at each index</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1], k = 0
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The score is max(nums) - min(nums) = 1 - 1 = 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,10], k = 2
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Change nums to be [2, 8]. The score is max(nums) - min(nums) = 8 - 2 = 6.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,6], k = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Change nums to be [4, 6, 3]. The score is max(nums) - min(nums) = 6 - 3 = 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= k &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/smallest-range-ii/smallest_range_ii.go b/problems/smallest-range-ii/smallest_range_ii.go
deleted file mode 100644
index d1f0c1a54..000000000
--- a/problems/smallest-range-ii/smallest_range_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem910
diff --git a/problems/smallest-range-ii/smallest_range_ii_test.go b/problems/smallest-range-ii/smallest_range_ii_test.go
deleted file mode 100644
index d1f0c1a54..000000000
--- a/problems/smallest-range-ii/smallest_range_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem910
diff --git a/problems/smallest-rectangle-enclosing-black-pixels/README.md b/problems/smallest-rectangle-enclosing-black-pixels/README.md
deleted file mode 100644
index 032a287b9..000000000
--- a/problems/smallest-rectangle-enclosing-black-pixels/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-invalid-parentheses "Remove Invalid Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../range-sum-query-immutable "Range Sum Query - Immutable")
-
-## [302. Smallest Rectangle Enclosing Black Pixels (Hard)](https://leetcode.com/problems/smallest-rectangle-enclosing-black-pixels "包含全部黑色像素的最小矩形")
-
-<p>An image is represented by a binary matrix with <code>0</code> as a white pixel and <code>1</code> as a black pixel. The black pixels are connected, i.e., there is only one black region. Pixels are connected horizontally and vertically. Given the location <code>(x, y)</code> of one of the black pixels, return the area of the smallest (axis-aligned) rectangle that encloses all black pixels.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong>
-[
-  &quot;0010&quot;,
-  &quot;0110&quot;,
-  &quot;0100&quot;
-]
-and <code>x = 0<font face="sans-serif, Arial, Verdana, Trebuchet MS">, </font></code><code>y = 2</code>
-
-<strong>Output:</strong> 6
-</pre>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/smallest-rectangle-enclosing-black-pixels/smallest_rectangle_enclosing_black_pixels.go b/problems/smallest-rectangle-enclosing-black-pixels/smallest_rectangle_enclosing_black_pixels.go
deleted file mode 100644
index 0771bf21e..000000000
--- a/problems/smallest-rectangle-enclosing-black-pixels/smallest_rectangle_enclosing_black_pixels.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem302
diff --git a/problems/smallest-rectangle-enclosing-black-pixels/smallest_rectangle_enclosing_black_pixels_test.go b/problems/smallest-rectangle-enclosing-black-pixels/smallest_rectangle_enclosing_black_pixels_test.go
deleted file mode 100644
index 0771bf21e..000000000
--- a/problems/smallest-rectangle-enclosing-black-pixels/smallest_rectangle_enclosing_black_pixels_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem302
diff --git a/problems/smallest-rotation-with-highest-score/README.md b/problems/smallest-rotation-with-highest-score/README.md
deleted file mode 100644
index 5cc70c886..000000000
--- a/problems/smallest-rotation-with-highest-score/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-paths-from-source-to-target "All Paths From Source to Target")
-　　　　　　　　　　　　　　　　
-[Next >](../champagne-tower "Champagne Tower")
-
-## [798. Smallest Rotation with Highest Score (Hard)](https://leetcode.com/problems/smallest-rotation-with-highest-score "得分最高的最小轮调")
-
-<p>You are given an array <code>nums</code>. You can rotate it by a non-negative integer <code>k</code> so that the array becomes <code>[nums[k], nums[k + 1], ... nums[nums.length - 1], nums[0], nums[1], ..., nums[k-1]]</code>. Afterward, any entries that are less than or equal to their index are worth one point.</p>
-
-<ul>
-	<li>For example, if we have <code>nums = [2,4,1,3,0]</code>, and we rotate by <code>k = 2</code>, it becomes <code>[1,3,0,2,4]</code>. This is worth <code>3</code> points because <code>1 &gt; 0</code> [no points], <code>3 &gt; 1</code> [no points], <code>0 &lt;= 2</code> [one point], <code>2 &lt;= 3</code> [one point], <code>4 &lt;= 4</code> [one point].</li>
-</ul>
-
-<p>Return <em>the rotation index </em><code>k</code><em> that corresponds to the highest score we can achieve if we rotated </em><code>nums</code><em> by it</em>. If there are multiple answers, return the smallest such index <code>k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,1,4,0]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Scores for each k are listed below: 
-k = 0,  nums = [2,3,1,4,0],    score 2
-k = 1,  nums = [3,1,4,0,2],    score 3
-k = 2,  nums = [1,4,0,2,3],    score 3
-k = 3,  nums = [4,0,2,3,1],    score 4
-k = 4,  nums = [0,2,3,1,4],    score 3
-So we should choose k = 3, which has the highest score.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,0,2,4]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> nums will always have 3 points no matter how it shifts.
-So we will choose the smallest k, which is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt; nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
diff --git a/problems/smallest-rotation-with-highest-score/smallest_rotation_with_highest_score.go b/problems/smallest-rotation-with-highest-score/smallest_rotation_with_highest_score.go
deleted file mode 100644
index 548bc784b..000000000
--- a/problems/smallest-rotation-with-highest-score/smallest_rotation_with_highest_score.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem798
diff --git a/problems/smallest-rotation-with-highest-score/smallest_rotation_with_highest_score_test.go b/problems/smallest-rotation-with-highest-score/smallest_rotation_with_highest_score_test.go
deleted file mode 100644
index 548bc784b..000000000
--- a/problems/smallest-rotation-with-highest-score/smallest_rotation_with_highest_score_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem798
diff --git a/problems/smallest-string-starting-from-leaf/README.md b/problems/smallest-string-starting-from-leaf/README.md
deleted file mode 100644
index 9b0831735..000000000
--- a/problems/smallest-string-starting-from-leaf/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../vertical-order-traversal-of-a-binary-tree "Vertical Order Traversal of a Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../add-to-array-form-of-integer "Add to Array-Form of Integer")
-
-## [988. Smallest String Starting From Leaf (Medium)](https://leetcode.com/problems/smallest-string-starting-from-leaf "从叶结点开始的最小字符串")
-
-<p>You are given the <code>root</code> of a binary tree where each node has a value in the range <code>[0, 25]</code> representing the letters <code>&#39;a&#39;</code> to <code>&#39;z&#39;</code>.</p>
-
-<p>Return <em>the <strong>lexicographically smallest</strong> string that starts at a leaf of this tree and ends at the root</em>.</p>
-
-<p>As a reminder, any shorter prefix of a string is <strong>lexicographically smaller</strong>.</p>
-
-<ul>
-	<li>For example, <code>&quot;ab&quot;</code> is lexicographically smaller than <code>&quot;aba&quot;</code>.</li>
-</ul>
-
-<p>A leaf of a node is a node that has no children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/30/tree1.png" style="width: 534px; height: 358px;" />
-<pre>
-<strong>Input:</strong> root = [0,1,2,3,4,3,4]
-<strong>Output:</strong> &quot;dba&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/01/30/tree2.png" style="width: 534px; height: 358px;" />
-<pre>
-<strong>Input:</strong> root = [25,1,3,1,3,0,2]
-<strong>Output:</strong> &quot;adz&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/02/01/tree3.png" style="height: 490px; width: 468px;" />
-<pre>
-<strong>Input:</strong> root = [2,2,1,null,1,0,null,0]
-<strong>Output:</strong> &quot;abc&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 8500]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 25</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Sum Root to Leaf Numbers](../sum-root-to-leaf-numbers) (Medium)
-  1. [Binary Tree Paths](../binary-tree-paths) (Easy)
diff --git a/problems/smallest-string-starting-from-leaf/smallest_string_starting_from_leaf.go b/problems/smallest-string-starting-from-leaf/smallest_string_starting_from_leaf.go
deleted file mode 100644
index 739b75edf..000000000
--- a/problems/smallest-string-starting-from-leaf/smallest_string_starting_from_leaf.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem988
diff --git a/problems/smallest-string-with-a-given-numeric-value/README.md b/problems/smallest-string-with-a-given-numeric-value/README.md
deleted file mode 100644
index 031de599d..000000000
--- a/problems/smallest-string-with-a-given-numeric-value/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-two-string-arrays-are-equivalent "Check If Two String Arrays are Equivalent")
-　　　　　　　　　　　　　　　　
-[Next >](../ways-to-make-a-fair-array "Ways to Make a Fair Array")
-
-## [1663. Smallest String With A Given Numeric Value (Medium)](https://leetcode.com/problems/smallest-string-with-a-given-numeric-value "具有给定数值的最小字符串")
-
-<p>The <strong>numeric value</strong> of a <strong>lowercase character</strong> is defined as its position <code>(1-indexed)</code> in the alphabet, so the numeric value of <code>a</code> is <code>1</code>, the numeric value of <code>b</code> is <code>2</code>, the numeric value of <code>c</code> is <code>3</code>, and so on.</p>
-
-<p>The <strong>numeric value</strong> of a <strong>string</strong> consisting of lowercase characters is defined as the sum of its characters&#39; numeric values. For example, the numeric value of the string <code>&quot;abe&quot;</code> is equal to <code>1 + 2 + 5 = 8</code>.</p>
-
-<p>You are given two integers <code>n</code> and <code>k</code>. Return <em>the <strong>lexicographically smallest string</strong> with <strong>length</strong> equal to <code>n</code> and <strong>numeric value</strong> equal to <code>k</code>.</em></p>
-
-<p>Note that a string <code>x</code> is lexicographically smaller than string <code>y</code> if <code>x</code> comes before <code>y</code> in dictionary order, that is, either <code>x</code> is a prefix of <code>y</code>, or if <code>i</code> is the first position such that <code>x[i] != y[i]</code>, then <code>x[i]</code> comes before <code>y[i]</code> in alphabetic order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 27
-<strong>Output:</strong> &quot;aay&quot;
-<strong>Explanation:</strong> The numeric value of the string is 1 + 1 + 25 = 27, and it is the smallest string with such a value and length equal to 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, k = 73
-<strong>Output:</strong> &quot;aaszz&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>n &lt;= k &lt;= 26 * n</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think greedily.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you build the string from the end to the beginning, it will always be optimal to put the highest possible character at the current index.
-</details>
diff --git a/problems/smallest-string-with-swaps/README.md b/problems/smallest-string-with-swaps/README.md
deleted file mode 100644
index 4275dfbf4..000000000
--- a/problems/smallest-string-with-swaps/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ugly-number-iii "Ugly Number III")
-　　　　　　　　　　　　　　　　
-[Next >](../sort-items-by-groups-respecting-dependencies "Sort Items by Groups Respecting Dependencies")
-
-## [1202. Smallest String With Swaps (Medium)](https://leetcode.com/problems/smallest-string-with-swaps "交换字符串中的元素")
-
-<p>You are given a string <code>s</code>, and an array of pairs of indices in the string&nbsp;<code>pairs</code>&nbsp;where&nbsp;<code>pairs[i] =&nbsp;[a, b]</code>&nbsp;indicates 2 indices(0-indexed) of the string.</p>
-
-<p>You can&nbsp;swap the characters at any pair of indices in the given&nbsp;<code>pairs</code>&nbsp;<strong>any number of times</strong>.</p>
-
-<p>Return the&nbsp;lexicographically smallest string that <code>s</code>&nbsp;can be changed to after using the swaps.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;dcab&quot;, pairs = [[0,3],[1,2]]
-<strong>Output:</strong> &quot;bacd&quot;
-<strong>Explaination:</strong> 
-Swap s[0] and s[3], s = &quot;bcad&quot;
-Swap s[1] and s[2], s = &quot;bacd&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;dcab&quot;, pairs = [[0,3],[1,2],[0,2]]
-<strong>Output:</strong> &quot;abcd&quot;
-<strong>Explaination: </strong>
-Swap s[0] and s[3], s = &quot;bcad&quot;
-Swap s[0] and s[2], s = &quot;acbd&quot;
-Swap s[1] and s[2], s = &quot;abcd&quot;</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cba&quot;, pairs = [[0,1],[1,2]]
-<strong>Output:</strong> &quot;abc&quot;
-<strong>Explaination: </strong>
-Swap s[0] and s[1], s = &quot;bca&quot;
-Swap s[1] and s[2], s = &quot;bac&quot;
-Swap s[0] and s[1], s = &quot;abc&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10^5</code></li>
-	<li><code>0 &lt;= pairs.length &lt;= 10^5</code></li>
-	<li><code>0 &lt;= pairs[i][0], pairs[i][1] &lt;&nbsp;s.length</code></li>
-	<li><code>s</code>&nbsp;only contains lower case English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-
-### Similar Questions
-  1. [Minimize Hamming Distance After Swap Operations](../minimize-hamming-distance-after-swap-operations) (Medium)
-  1. [Process Restricted Friend Requests](../process-restricted-friend-requests) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think of it as a graph problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Consider the pairs as connected nodes in the graph, what can you do with a connected component of indices ?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We can sort each connected component alone to get the lexicographically minimum string.
-</details>
diff --git a/problems/smallest-subsequence-of-distinct-characters/README.md b/problems/smallest-subsequence-of-distinct-characters/README.md
deleted file mode 100644
index 8df56998f..000000000
--- a/problems/smallest-subsequence-of-distinct-characters/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../insufficient-nodes-in-root-to-leaf-paths "Insufficient Nodes in Root to Leaf Paths")
-　　　　　　　　　　　　　　　　
-[Next >](../sales-analysis-i "Sales Analysis I")
-
-## [1081. Smallest Subsequence of Distinct Characters (Medium)](https://leetcode.com/problems/smallest-subsequence-of-distinct-characters "不同字符的最小子序列")
-
-<p>Given a string <code>s</code>, return <em>the lexicographically smallest subsequence of</em> <code>s</code> <em>that contains all the distinct characters of</em> <code>s</code> <em>exactly once</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bcabc&quot;
-<strong>Output:</strong> &quot;abc&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cbacdcbc&quot;
-<strong>Output:</strong> &quot;acdb&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Note:</strong> This question is the same as 316: <a href="https://leetcode.com/problems/remove-duplicate-letters/" target="_blank">https://leetcode.com/problems/remove-duplicate-letters/</a>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Greedily try to add one missing character. How to check if adding some character will not cause problems ? Use bit-masks to check whether you will be able to complete the sub-sequence if you add the character at some index i.
-</details>
diff --git a/problems/smallest-subsequence-of-distinct-characters/smallest_subsequence_of_distinct_characters.go b/problems/smallest-subsequence-of-distinct-characters/smallest_subsequence_of_distinct_characters.go
deleted file mode 100644
index 6be566f4b..000000000
--- a/problems/smallest-subsequence-of-distinct-characters/smallest_subsequence_of_distinct_characters.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem1081
-
-import "strings"
-
-func smallestSubsequence(S string) string {
-	n := len(S)
-
-	last := [26]int{}
-	for i, c := range S {
-		last[c-'a'] = i
-	}
-
-	stack, top := make([]int, n), -1
-	hasSeen := [26]bool{}
-	for i := 0; i < n; i++ {
-		c := int(S[i] - 'a')
-		if hasSeen[c] {
-			continue
-		}
-		for top >= 0 &&
-			stack[top] > c &&
-			i < last[stack[top]] {
-			pop := stack[top]
-			top--
-			hasSeen[pop] = false
-		}
-		top++
-		stack[top] = c
-		hasSeen[c] = true
-	}
-
-	var sb strings.Builder
-	for i := 0; i <= top; i++ {
-		b := byte(stack[i] + 'a')
-		sb.WriteByte(b)
-	}
-
-	return sb.String()
-}
diff --git a/problems/smallest-subtree-with-all-the-deepest-nodes/README.md b/problems/smallest-subtree-with-all-the-deepest-nodes/README.md
deleted file mode 100644
index f7479d7cc..000000000
--- a/problems/smallest-subtree-with-all-the-deepest-nodes/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-path-to-get-all-keys "Shortest Path to Get All Keys")
-　　　　　　　　　　　　　　　　
-[Next >](../prime-palindrome "Prime Palindrome")
-
-## [865. Smallest Subtree with all the Deepest Nodes (Medium)](https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes "具有所有最深节点的最小子树")
-
-<p>Given the <code>root</code> of a binary tree, the depth of each node is <strong>the shortest distance to the root</strong>.</p>
-
-<p>Return <em>the smallest subtree</em> such that it contains <strong>all the deepest nodes</strong> in the original tree.</p>
-
-<p>A node is called <strong>the deepest</strong> if it has the largest depth possible among any node in the entire tree.</p>
-
-<p>The <strong>subtree</strong> of a node is a tree consisting of that node, plus the set of all descendants of that node.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/07/01/sketch1.png" style="width: 600px; height: 510px;" />
-<pre>
-<strong>Input:</strong> root = [3,5,1,6,2,0,8,null,null,7,4]
-<strong>Output:</strong> [2,7,4]
-<strong>Explanation:</strong> We return the node with value 2, colored in yellow in the diagram.
-The nodes coloured in blue are the deepest nodes of the tree.
-Notice that nodes 5, 3 and 2 contain the deepest nodes in the tree but node 2 is the smallest subtree among them, so we return it.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> [1]
-<strong>Explanation:</strong> The root is the deepest node in the tree.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [0,1,3,null,2]
-<strong>Output:</strong> [2]
-<strong>Explanation:</strong> The deepest node in the tree is 2, the valid subtrees are the subtrees of nodes 2, 1 and 0 but the subtree of node 2 is the smallest.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree will be in the range <code>[1, 500]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 500</code></li>
-	<li>The values of the nodes in the tree are <strong>unique</strong>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Note:</strong> This question is the same as 1123: <a href="https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves/" target="_blank">https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves/</a></p>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/smallest-subtree-with-all-the-deepest-nodes/smallest_subtree_with_all_the_deepest_nodes.go b/problems/smallest-subtree-with-all-the-deepest-nodes/smallest_subtree_with_all_the_deepest_nodes.go
deleted file mode 100644
index 526afcb60..000000000
--- a/problems/smallest-subtree-with-all-the-deepest-nodes/smallest_subtree_with_all_the_deepest_nodes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem865
diff --git a/problems/smallest-subtree-with-all-the-deepest-nodes/smallest_subtree_with_all_the_deepest_nodes_test.go b/problems/smallest-subtree-with-all-the-deepest-nodes/smallest_subtree_with_all_the_deepest_nodes_test.go
deleted file mode 100644
index 526afcb60..000000000
--- a/problems/smallest-subtree-with-all-the-deepest-nodes/smallest_subtree_with_all_the_deepest_nodes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem865
diff --git a/problems/smallest-sufficient-team/README.md b/problems/smallest-sufficient-team/README.md
deleted file mode 100644
index eca83514e..000000000
--- a/problems/smallest-sufficient-team/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-well-performing-interval "Longest Well-Performing Interval")
-　　　　　　　　　　　　　　　　
-[Next >](../active-businesses "Active Businesses")
-
-## [1125. Smallest Sufficient Team (Hard)](https://leetcode.com/problems/smallest-sufficient-team "最小的必要团队")
-
-<p>In a project, you have a list of required skills <code>req_skills</code>, and a list of people. The <code>i<sup>th</sup></code> person <code>people[i]</code> contains a list of skills that the person has.</p>
-
-<p>Consider a sufficient team: a set of people such that for every required skill in <code>req_skills</code>, there is at least one person in the team who has that skill. We can represent these teams by the index of each person.</p>
-
-<ul>
-	<li>For example, <code>team = [0, 1, 3]</code> represents the people with skills <code>people[0]</code>, <code>people[1]</code>, and <code>people[3]</code>.</li>
-</ul>
-
-<p>Return <em>any sufficient team of the smallest possible size, represented by the index of each person</em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>It is <strong>guaranteed</strong> an answer exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> req_skills = ["java","nodejs","reactjs"], people = [["java"],["nodejs"],["nodejs","reactjs"]]
-<strong>Output:</strong> [0,2]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> req_skills = ["algorithms","math","java","reactjs","csharp","aws"], people = [["algorithms","math","java"],["algorithms","math","reactjs"],["java","csharp","aws"],["reactjs","csharp"],["csharp","math"],["aws","java"]]
-<strong>Output:</strong> [1,2]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= req_skills.length &lt;= 16</code></li>
-	<li><code>1 &lt;= req_skills[i].length &lt;= 16</code></li>
-	<li><code>req_skills[i]</code> consists of lowercase English letters.</li>
-	<li>All the strings of <code>req_skills</code> are <strong>unique</strong>.</li>
-	<li><code>1 &lt;= people.length &lt;= 60</code></li>
-	<li><code>0 &lt;= people[i].length &lt;= 16</code></li>
-	<li><code>1 &lt;= people[i][j].length &lt;= 16</code></li>
-	<li><code>people[i][j]</code> consists of lowercase English letters.</li>
-	<li>All the strings of <code>people[i]</code> are <strong>unique</strong>.</li>
-	<li>Every skill in <code>people[i]</code> is a skill in <code>req_skills</code>.</li>
-	<li>It is guaranteed a sufficient team exists.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Similar Questions
-  1. [The Number of Good Subsets](../the-number-of-good-subsets) (Hard)
-  1. [Minimum Number of Work Sessions to Finish the Tasks](../minimum-number-of-work-sessions-to-finish-the-tasks) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Do a bitmask DP.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each person, for each set of skills, we can update our understanding of a minimum set of people needed to perform this set of skills.
-</details>
diff --git a/problems/smallest-sufficient-team/smallest_sufficient_team.go b/problems/smallest-sufficient-team/smallest_sufficient_team.go
deleted file mode 100644
index 96a34c17e..000000000
--- a/problems/smallest-sufficient-team/smallest_sufficient_team.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem1125
diff --git a/problems/smallest-value-of-the-rearranged-number/README.md b/problems/smallest-value-of-the-rearranged-number/README.md
deleted file mode 100644
index 3d029d147..000000000
--- a/problems/smallest-value-of-the-rearranged-number/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-even-and-odd-indices-independently "Sort Even and Odd Indices Independently")
-　　　　　　　　　　　　　　　　
-[Next >](../design-bitset "Design Bitset")
-
-## [2165. Smallest Value of the Rearranged Number (Medium)](https://leetcode.com/problems/smallest-value-of-the-rearranged-number "重排数字的最小值")
-
-<p>You are given an integer <code>num.</code> <strong>Rearrange</strong> the digits of <code>num</code> such that its value is <strong>minimized</strong> and it does not contain <strong>any</strong> leading zeros.</p>
-
-<p>Return <em>the rearranged number with minimal value</em>.</p>
-
-<p>Note that the sign of the number does not change after rearranging the digits.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = 310
-<strong>Output:</strong> 103
-<strong>Explanation:</strong> The possible arrangements for the digits of 310 are 013, 031, 103, 130, 301, 310. 
-The arrangement with the smallest value that does not contain any leading zeros is 103.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = -7605
-<strong>Output:</strong> -7650
-<strong>Explanation:</strong> Some possible arrangements for the digits of -7605 are -7650, -6705, -5076, -0567.
-The arrangement with the smallest value that does not contain any leading zeros is -7650.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-10<sup>15</sup> &lt;= num &lt;= 10<sup>15</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For positive numbers, the leading digit should be the smallest nonzero digit. Then the remaining digits follow in ascending order.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For negative numbers, the digits should be arranged in descending order.
-</details>
diff --git a/problems/snakes-and-ladders/README.md b/problems/snakes-and-ladders/README.md
deleted file mode 100644
index ec54e4fac..000000000
--- a/problems/snakes-and-ladders/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-range-i "Smallest Range I")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-range-ii "Smallest Range II")
-
-## [909. Snakes and Ladders (Medium)](https://leetcode.com/problems/snakes-and-ladders "蛇梯棋")
-
-<p>You are given an <code>n x n</code> integer matrix <code>board</code> where the cells are labeled from <code>1</code> to <code>n<sup>2</sup></code> in a <a href="https://en.wikipedia.org/wiki/Boustrophedon" target="_blank"><strong>Boustrophedon style</strong></a> starting from the bottom left of the board (i.e. <code>board[n - 1][0]</code>) and alternating direction each row.</p>
-
-<p>You start on square <code>1</code> of the board. In each move, starting from square <code>curr</code>, do the following:</p>
-
-<ul>
-	<li>Choose a destination square <code>next</code> with a label in the range <code>[curr + 1, min(curr + 6, n<sup>2</sup>)]</code>.
-	<ul>
-		<li>This choice simulates the result of a standard <strong>6-sided die roll</strong>: i.e., there are always at most 6 destinations, regardless of the size of the board.</li>
-	</ul>
-	</li>
-	<li>If <code>next</code> has a snake or ladder, you <strong>must</strong> move to the destination of that snake or ladder. Otherwise, you move to <code>next</code>.</li>
-	<li>The game ends when you reach the square <code>n<sup>2</sup></code>.</li>
-</ul>
-
-<p>A board square on row <code>r</code> and column <code>c</code> has a snake or ladder if <code>board[r][c] != -1</code>. The destination of that snake or ladder is <code>board[r][c]</code>. Squares <code>1</code> and <code>n<sup>2</sup></code> do not have a snake or ladder.</p>
-
-<p>Note that you only take a snake or ladder at most once per move. If the destination to a snake or ladder is the start of another snake or ladder, you do <strong>not</strong> follow the subsequent&nbsp;snake or ladder.</p>
-
-<ul>
-	<li>For example, suppose the board is <code>[[-1,4],[-1,3]]</code>, and on the first move, your destination square is <code>2</code>. You follow the ladder to square <code>3</code>, but do <strong>not</strong> follow the subsequent ladder to <code>4</code>.</li>
-</ul>
-
-<p>Return <em>the least number of moves required to reach the square </em><code>n<sup>2</sup></code><em>. If it is not possible to reach the square, return </em><code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/09/23/snakes.png" style="width: 500px; height: 394px;" />
-<pre>
-<strong>Input:</strong> board = [[-1,-1,-1,-1,-1,-1],[-1,-1,-1,-1,-1,-1],[-1,-1,-1,-1,-1,-1],[-1,35,-1,-1,13,-1],[-1,-1,-1,-1,-1,-1],[-1,15,-1,-1,-1,-1]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> 
-In the beginning, you start at square 1 (at row 5, column 0).
-You decide to move to square 2 and must take the ladder to square 15.
-You then decide to move to square 17 and must take the snake to square 13.
-You then decide to move to square 14 and must take the ladder to square 35.
-You then decide to move to square 36, ending the game.
-This is the lowest possible number of moves to reach the last square, so return 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> board = [[-1,-1],[-1,3]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == board.length == board[i].length</code></li>
-	<li><code>2 &lt;= n &lt;= 20</code></li>
-	<li><code>grid[i][j]</code> is either <code>-1</code> or in the range <code>[1, n<sup>2</sup>]</code>.</li>
-	<li>The squares labeled <code>1</code> and <code>n<sup>2</sup></code> do not have any ladders or snakes.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/snakes-and-ladders/snakes_and_ladders.go b/problems/snakes-and-ladders/snakes_and_ladders.go
deleted file mode 100644
index b0481c894..000000000
--- a/problems/snakes-and-ladders/snakes_and_ladders.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem909
diff --git a/problems/snakes-and-ladders/snakes_and_ladders_test.go b/problems/snakes-and-ladders/snakes_and_ladders_test.go
deleted file mode 100644
index b0481c894..000000000
--- a/problems/snakes-and-ladders/snakes_and_ladders_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem909
diff --git a/problems/snapshot-array/README.md b/problems/snapshot-array/README.md
deleted file mode 100644
index b754c70a6..000000000
--- a/problems/snapshot-array/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-coloring-game "Binary Tree Coloring Game")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-chunked-palindrome-decomposition "Longest Chunked Palindrome Decomposition")
-
-## [1146. Snapshot Array (Medium)](https://leetcode.com/problems/snapshot-array "快照数组")
-
-<p>Implement a SnapshotArray that supports the following interface:</p>
-
-<ul>
-	<li><code>SnapshotArray(int length)</code> initializes an array-like data structure with the given length.&nbsp; <strong>Initially, each element equals 0</strong>.</li>
-	<li><code>void set(index, val)</code> sets the element at the given <code>index</code> to be equal to <code>val</code>.</li>
-	<li><code>int snap()</code>&nbsp;takes a snapshot of the array and returns the <code>snap_id</code>: the total number of times we called <code>snap()</code> minus <code>1</code>.</li>
-	<li><code>int get(index, snap_id)</code>&nbsp;returns the value at the given <code>index</code>, at the time we took the snapshot with the given <code>snap_id</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> [&quot;SnapshotArray&quot;,&quot;set&quot;,&quot;snap&quot;,&quot;set&quot;,&quot;get&quot;]
-[[3],[0,5],[],[0,6],[0,0]]
-<strong>Output:</strong> [null,null,0,null,5]
-<strong>Explanation: </strong>
-SnapshotArray snapshotArr = new SnapshotArray(3); // set the length to be 3
-snapshotArr.set(0,5);  // Set array[0] = 5
-snapshotArr.snap();  // Take a snapshot, return snap_id = 0
-snapshotArr.set(0,6);
-snapshotArr.get(0,0);  // Get the value of array[0] with snap_id = 0, return 5</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= length&nbsp;&lt;= 50000</code></li>
-	<li>At most <code>50000</code>&nbsp;calls will be made to <code>set</code>, <code>snap</code>, and <code>get</code>.</li>
-	<li><code>0 &lt;= index&nbsp;&lt;&nbsp;length</code></li>
-	<li><code>0 &lt;=&nbsp;snap_id &lt;&nbsp;</code>(the total number of times we call <code>snap()</code>)</li>
-	<li><code>0 &lt;=&nbsp;val &lt;= 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a list of lists, adding both the element and the snap_id to each index.
-</details>
diff --git a/problems/solve-the-equation/README.md b/problems/solve-the-equation/README.md
deleted file mode 100644
index b3c314bab..000000000
--- a/problems/solve-the-equation/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decode-ways-ii "Decode Ways II")
-　　　　　　　　　　　　　　　　
-[Next >](../design-circular-deque "Design Circular Deque")
-
-## [640. Solve the Equation (Medium)](https://leetcode.com/problems/solve-the-equation "求解方程")
-
-<p>Solve a given equation and return the value of <code>&#39;x&#39;</code> in the form of a string <code>&quot;x=#value&quot;</code>. The equation contains only <code>&#39;+&#39;</code>, <code>&#39;-&#39;</code> operation, the variable <code>&#39;x&#39;</code> and its coefficient. You should return <code>&quot;No solution&quot;</code> if there is no solution for the equation, or <code>&quot;Infinite solutions&quot;</code> if there are infinite solutions for the equation.</p>
-
-<p>If there is exactly one solution for the equation, we ensure that the value of <code>&#39;x&#39;</code> is an integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> equation = "x+5-3+x=6+x-2"
-<strong>Output:</strong> "x=2"
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> equation = "x=x"
-<strong>Output:</strong> "Infinite solutions"
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> equation = "2x=x"
-<strong>Output:</strong> "x=0"
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> equation = "2x+3x-6x=x+2"
-<strong>Output:</strong> "x=-1"
-</pre><p><strong>Example 5:</strong></p>
-<pre><strong>Input:</strong> equation = "x=x+2"
-<strong>Output:</strong> "No solution"
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= equation.length &lt;= 1000</code></li>
-	<li><code>equation</code> has exactly one <code>&#39;=&#39;</code>.</li>
-	<li><code>equation</code> consists of integers with an absolute value in the range <code>[0, 100]</code> without any leading zeros, and the variable <code>&#39;x&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Fraction Addition and Subtraction](../fraction-addition-and-subtraction) (Medium)
diff --git a/problems/solve-the-equation/solve_the_equation.go b/problems/solve-the-equation/solve_the_equation.go
deleted file mode 100644
index 916229887..000000000
--- a/problems/solve-the-equation/solve_the_equation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem640
diff --git a/problems/solve-the-equation/solve_the_equation_test.go b/problems/solve-the-equation/solve_the_equation_test.go
deleted file mode 100644
index 916229887..000000000
--- a/problems/solve-the-equation/solve_the_equation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem640
diff --git a/problems/solving-questions-with-brainpower/README.md b/problems/solving-questions-with-brainpower/README.md
deleted file mode 100644
index 91656b129..000000000
--- a/problems/solving-questions-with-brainpower/README.md
+++ /dev/null
@@ -1,92 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-moves-to-reach-target-score "Minimum Moves to Reach Target Score")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-running-time-of-n-computers "Maximum Running Time of N Computers")
-
-## [2140. Solving Questions With Brainpower (Medium)](https://leetcode.com/problems/solving-questions-with-brainpower "解决智力问题")
-
-<p>You are given a <strong>0-indexed</strong> 2D integer array <code>questions</code> where <code>questions[i] = [points<sub>i</sub>, brainpower<sub>i</sub>]</code>.</p>
-
-<p>The array describes the questions of an exam, where you have to process the questions <strong>in order</strong> (i.e., starting from question <code>0</code>) and make a decision whether to <strong>solve</strong> or <strong>skip</strong> each question. Solving question <code>i</code> will <strong>earn</strong> you <code>points<sub>i</sub></code> points but you will be <strong>unable</strong> to solve each of the next <code>brainpower<sub>i</sub></code> questions. If you skip question <code>i</code>, you get to make the decision on the next question.</p>
-
-<ul>
-	<li>For example, given <code>questions = [[3, 2], [4, 3], [4, 4], [2, 5]]</code>:
-	<ul>
-		<li>If question <code>0</code> is solved, you will earn <code>3</code> points but you will be unable to solve questions <code>1</code> and <code>2</code>.</li>
-		<li>If instead, question <code>0</code> is skipped and question <code>1</code> is solved, you will earn <code>4</code> points but you will be unable to solve questions <code>2</code> and <code>3</code>.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <em>the <strong>maximum</strong> points you can earn for the exam</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> questions = [[3,2],[4,3],[4,4],[2,5]]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The maximum points can be earned by solving questions 0 and 3.
-- Solve question 0: Earn 3 points, will be unable to solve the next 2 questions
-- Unable to solve questions 1 and 2
-- Solve question 3: Earn 2 points
-Total points earned: 3 + 2 = 5. There is no other way to earn 5 or more points.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> questions = [[1,1],[2,2],[3,3],[4,4],[5,5]]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The maximum points can be earned by solving questions 1 and 4.
-- Skip question 0
-- Solve question 1: Earn 2 points, will be unable to solve the next 2 questions
-- Unable to solve questions 2 and 3
-- Solve question 4: Earn 5 points
-Total points earned: 2 + 5 = 7. There is no other way to earn 7 or more points.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= questions.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>questions[i].length == 2</code></li>
-	<li><code>1 &lt;= points<sub>i</sub>, brainpower<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each question, we can either solve it or skip it. How can we use Dynamic Programming to decide the most optimal option for each problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We store for each question the maximum points we can earn if we started the exam on that question.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If we skip a question, then the answer for it will be the same as the answer for the next question.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-If we solve a question, then the answer for it will be the points of the current question plus the answer for the next solvable question.
-</details>
-
-<details>
-<summary>Hint 5</summary>
-The maximum of these two values will be the answer to the current question.
-</details>
diff --git a/problems/sort-an-array/README.md b/problems/sort-an-array/README.md
deleted file mode 100644
index eade2aa53..000000000
--- a/problems/sort-an-array/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../online-election "Online Election")
-　　　　　　　　　　　　　　　　
-[Next >](../cat-and-mouse "Cat and Mouse")
-
-## [912. Sort an Array (Medium)](https://leetcode.com/problems/sort-an-array "排序数组")
-
-<p>Given an array of integers <code>nums</code>, sort the array in ascending order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [5,2,3,1]
-<strong>Output:</strong> [1,2,3,5]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [5,1,1,2,0,0]
-<strong>Output:</strong> [0,0,1,1,2,5]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>-5 * 10<sup>4</sup> &lt;= nums[i] &lt;= 5 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Merge Sort](../../tag/merge-sort/README.md)]
-  [[Bucket Sort](../../tag/bucket-sort/README.md)]
-  [[Radix Sort](../../tag/radix-sort/README.md)]
-  [[Counting Sort](../../tag/counting-sort/README.md)]
diff --git a/problems/sort-an-array/sort_an_array.go b/problems/sort-an-array/sort_an_array.go
deleted file mode 100644
index 10c569143..000000000
--- a/problems/sort-an-array/sort_an_array.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package problem912
-
-import "sort"
-
-func sortArray(nums []int) []int {
-	sort.Ints(nums)
-	return nums
-}
diff --git a/problems/sort-an-array/sort_an_array_test.go b/problems/sort-an-array/sort_an_array_test.go
deleted file mode 100644
index 92feff02f..000000000
--- a/problems/sort-an-array/sort_an_array_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem912
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestSortArray(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{5, 2, 3, 1},
-			want: []int{1, 2, 3, 5},
-		},
-		{
-			in:   []int{5, 1, 1, 2, 0, 0},
-			want: []int{0, 0, 1, 1, 2, 5},
-		},
-	}
-	for _, tt := range tests {
-		got := sortArray(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/sort-array-by-increasing-frequency/README.md b/problems/sort-array-by-increasing-frequency/README.md
deleted file mode 100644
index e5cbf4b46..000000000
--- a/problems/sort-array-by-increasing-frequency/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../hopper-company-queries-i "Hopper Company Queries I")
-　　　　　　　　　　　　　　　　
-[Next >](../widest-vertical-area-between-two-points-containing-no-points "Widest Vertical Area Between Two Points Containing No Points")
-
-## [1636. Sort Array by Increasing Frequency (Easy)](https://leetcode.com/problems/sort-array-by-increasing-frequency "按照频率将数组升序排序")
-
-<p>Given an array of integers <code>nums</code>, sort the array in <strong>increasing</strong> order based on the frequency of the values. If multiple values have the same frequency, sort them in <strong>decreasing</strong> order.</p>
-
-<p>Return the <em>sorted array</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,2,2,2,3]
-<strong>Output:</strong> [3,1,1,2,2,2]
-<strong>Explanation:</strong> &#39;3&#39; has a frequency of 1, &#39;1&#39; has a frequency of 2, and &#39;2&#39; has a frequency of 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,1,3,2]
-<strong>Output:</strong> [1,3,3,2,2]
-<strong>Explanation:</strong> &#39;2&#39; and &#39;3&#39; both have a frequency of 2, so they are sorted in decreasing order.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1,1,-6,4,5,-6,1,4,1]
-<strong>Output:</strong> [5,-1,4,4,-6,-6,1,1,1]</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the frequency of each value.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use a custom comparator to compare values by their frequency. If two values have the same frequency, compare their values.
-</details>
diff --git a/problems/sort-array-by-parity-ii/README.md b/problems/sort-array-by-parity-ii/README.md
deleted file mode 100644
index 4e89da7b4..000000000
--- a/problems/sort-array-by-parity-ii/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-add-to-make-parentheses-valid "Minimum Add to Make Parentheses Valid")
-　　　　　　　　　　　　　　　　
-[Next >](../3sum-with-multiplicity "3Sum With Multiplicity")
-
-## [922. Sort Array By Parity II (Easy)](https://leetcode.com/problems/sort-array-by-parity-ii "按奇偶排序数组 II")
-
-<p>Given an array of integers <code>nums</code>, half of the integers in <code>nums</code> are <strong>odd</strong>, and the other half are <strong>even</strong>.</p>
-
-<p>Sort the array so that whenever <code>nums[i]</code> is odd, <code>i</code> is <strong>odd</strong>, and whenever <code>nums[i]</code> is even, <code>i</code> is <strong>even</strong>.</p>
-
-<p>Return <em>any answer array that satisfies this condition</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,5,7]
-<strong>Output:</strong> [4,5,2,7]
-<strong>Explanation:</strong> [4,7,2,5], [2,5,4,7], [2,7,4,5] would also have been accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3]
-<strong>Output:</strong> [2,3]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>nums.length</code> is even.</li>
-	<li>Half of the integers in <code>nums</code> are even.</li>
-	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow Up:</strong> Could you solve it in-place?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/sort-array-by-parity-ii/sort_array_by_parity_ii.go b/problems/sort-array-by-parity-ii/sort_array_by_parity_ii.go
deleted file mode 100644
index 35e3dced4..000000000
--- a/problems/sort-array-by-parity-ii/sort_array_by_parity_ii.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem922
-
-func sortArrayByParityII(A []int) []int {
-	i, l := 0, len(A)
-	for j := 1; j < l; j += 2 {
-		if A[j]&1 == 0 {
-			for A[i]&1 == 0 {
-				i += 2
-			}
-			A[i], A[j] = A[j], A[i]
-		}
-	}
-	return A
-}
diff --git a/problems/sort-array-by-parity-ii/sort_array_by_parity_ii_test.go b/problems/sort-array-by-parity-ii/sort_array_by_parity_ii_test.go
deleted file mode 100644
index 847b97493..000000000
--- a/problems/sort-array-by-parity-ii/sort_array_by_parity_ii_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem922
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestSortArrayByParityII(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{4, 2, 5, 7},
-			want: []int{4, 5, 2, 7},
-		},
-		{
-			in:   []int{2, 3, 1, 1, 4, 0, 0, 4, 3, 3},
-			want: []int{2, 3, 0, 1, 4, 1, 0, 3, 4, 3},
-		},
-	}
-	for _, tt := range tests {
-		got := sortArrayByParityII(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/sort-array-by-parity/README.md b/problems/sort-array-by-parity/README.md
deleted file mode 100644
index 62b5fbb01..000000000
--- a/problems/sort-array-by-parity/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fruit-into-baskets "Fruit Into Baskets")
-　　　　　　　　　　　　　　　　
-[Next >](../super-palindromes "Super Palindromes")
-
-## [905. Sort Array By Parity (Easy)](https://leetcode.com/problems/sort-array-by-parity "按奇偶排序数组")
-
-<p>Given an integer array <code>nums</code>, move all the even integers at the beginning of the array followed by all the odd integers.</p>
-
-<p>Return <em><strong>any array</strong> that satisfies this condition</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1,2,4]
-<strong>Output:</strong> [2,4,3,1]
-<strong>Explanation:</strong> The outputs [4,2,3,1], [2,4,1,3], and [4,2,1,3] would also be accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0]
-<strong>Output:</strong> [0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5000</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 5000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/sort-array-by-parity/sort_array_by_parity.go b/problems/sort-array-by-parity/sort_array_by_parity.go
deleted file mode 100644
index 41857ba75..000000000
--- a/problems/sort-array-by-parity/sort_array_by_parity.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package problem905
-
-import "sort"
-
-func sortArrayByParity(A []int) []int {
-	sort.Slice(A, func(i, j int) bool {
-		return A[i]%2 < A[j]%2
-	})
-	return A
-}
diff --git a/problems/sort-array-by-parity/sort_array_by_parity_test.go b/problems/sort-array-by-parity/sort_array_by_parity_test.go
deleted file mode 100644
index cd78c5ed0..000000000
--- a/problems/sort-array-by-parity/sort_array_by_parity_test.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package problem905
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestSortArrayByParity(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{3, 1, 2, 4},
-			want: []int{2, 4, 3, 1},
-		},
-	}
-	for _, tt := range tests {
-		got := sortArrayByParity(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/sort-characters-by-frequency/README.md b/problems/sort-characters-by-frequency/README.md
deleted file mode 100644
index e33d946c7..000000000
--- a/problems/sort-characters-by-frequency/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-node-in-a-bst "Delete Node in a BST")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-arrows-to-burst-balloons "Minimum Number of Arrows to Burst Balloons")
-
-## [451. Sort Characters By Frequency (Medium)](https://leetcode.com/problems/sort-characters-by-frequency "根据字符出现频率排序")
-
-<p>Given a string <code>s</code>, sort it in decreasing order based on the frequency of characters, and return <em>the sorted string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;tree&quot;
-<strong>Output:</strong> &quot;eert&quot;
-<strong>Explanation:</strong> &#39;e&#39; appears twice while &#39;r&#39; and &#39;t&#39; both appear once.
-So &#39;e&#39; must appear before both &#39;r&#39; and &#39;t&#39;. Therefore &quot;eetr&quot; is also a valid answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cccaaa&quot;
-<strong>Output:</strong> &quot;aaaccc&quot;
-<strong>Explanation:</strong> Both &#39;c&#39; and &#39;a&#39; appear three times, so &quot;aaaccc&quot; is also a valid answer.
-Note that &quot;cacaca&quot; is incorrect, as the same characters must be together.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;Aabb&quot;
-<strong>Output:</strong> &quot;bbAa&quot;
-<strong>Explanation:</strong> &quot;bbaA&quot; is also a valid answer, but &quot;Aabb&quot; is incorrect.
-Note that &#39;A&#39; and &#39;a&#39; are treated as two different characters.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 5 * 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of English letters and digits.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Bucket Sort](../../tag/bucket-sort/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Top K Frequent Elements](../top-k-frequent-elements) (Medium)
-  1. [First Unique Character in a String](../first-unique-character-in-a-string) (Easy)
diff --git a/problems/sort-characters-by-frequency/sort_characters_by_frequency.go b/problems/sort-characters-by-frequency/sort_characters_by_frequency.go
deleted file mode 100644
index 2148d9601..000000000
--- a/problems/sort-characters-by-frequency/sort_characters_by_frequency.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem451
diff --git a/problems/sort-characters-by-frequency/sort_characters_by_frequency_test.go b/problems/sort-characters-by-frequency/sort_characters_by_frequency_test.go
deleted file mode 100644
index 2148d9601..000000000
--- a/problems/sort-characters-by-frequency/sort_characters_by_frequency_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem451
diff --git a/problems/sort-colors/README.md b/problems/sort-colors/README.md
deleted file mode 100644
index b5aed8325..000000000
--- a/problems/sort-colors/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../search-a-2d-matrix "Search a 2D Matrix")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-window-substring "Minimum Window Substring")
-
-## [75. Sort Colors (Medium)](https://leetcode.com/problems/sort-colors "颜色分类")
-
-<p>Given an array <code>nums</code> with <code>n</code> objects colored red, white, or blue, sort them <strong><a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank">in-place</a> </strong>so that objects of the same color are adjacent, with the colors in the order red, white, and blue.</p>
-
-<p>We will use the integers <code>0</code>, <code>1</code>, and <code>2</code> to represent the color red, white, and blue, respectively.</p>
-
-<p>You must solve this problem without using the library&#39;s sort function.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [2,0,2,1,1,0]
-<strong>Output:</strong> [0,0,1,1,2,2]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [2,0,1]
-<strong>Output:</strong> [0,1,2]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> nums = [0]
-<strong>Output:</strong> [0]
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> nums = [1]
-<strong>Output:</strong> [1]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == nums.length</code></li>
-	<li><code>1 &lt;= n &lt;= 300</code></li>
-	<li><code>nums[i]</code> is <code>0</code>, <code>1</code>, or <code>2</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong>&nbsp;Could you come up with a one-pass algorithm using only&nbsp;constant extra space?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Sort List](../sort-list) (Medium)
-  1. [Wiggle Sort](../wiggle-sort) (Medium)
-  1. [Wiggle Sort II](../wiggle-sort-ii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A rather straight forward solution is a two-pass algorithm using counting sort.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Iterate the array counting number of 0's, 1's, and 2's.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Overwrite array with the total number of 0's, then 1's and followed by 2's.
-</details>
diff --git a/problems/sort-colors/sort_colors.go b/problems/sort-colors/sort_colors.go
deleted file mode 100644
index 5d1347f5d..000000000
--- a/problems/sort-colors/sort_colors.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem75
diff --git a/problems/sort-colors/sort_colors_test.go b/problems/sort-colors/sort_colors_test.go
deleted file mode 100644
index 5d1347f5d..000000000
--- a/problems/sort-colors/sort_colors_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem75
diff --git a/problems/sort-even-and-odd-indices-independently/README.md b/problems/sort-even-and-odd-indices-independently/README.md
deleted file mode 100644
index 9cf9fc559..000000000
--- a/problems/sort-even-and-odd-indices-independently/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-difference-in-sums-after-removal-of-elements "Minimum Difference in Sums After Removal of Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-value-of-the-rearranged-number "Smallest Value of the Rearranged Number")
-
-## [2164. Sort Even and Odd Indices Independently (Easy)](https://leetcode.com/problems/sort-even-and-odd-indices-independently "对奇偶下标分别排序")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code>. Rearrange the values of <code>nums</code> according to the following rules:</p>
-
-<ol>
-	<li>Sort the values at <strong>odd indices</strong> of <code>nums</code> in <strong>non-increasing</strong> order.
-	<ul>
-		<li>For example, if <code>nums = [4,<strong><u>1</u></strong>,2,<u><strong>3</strong></u>]</code> before this step, it becomes <code>[4,<u><strong>3</strong></u>,2,<strong><u>1</u></strong>]</code> after. The values at odd indices <code>1</code> and <code>3</code> are sorted in non-increasing order.</li>
-	</ul>
-	</li>
-	<li>Sort the values at <strong>even indices</strong> of <code>nums</code> in <strong>non-decreasing</strong> order.
-	<ul>
-		<li>For example, if <code>nums = [<u><strong>4</strong></u>,1,<u><strong>2</strong></u>,3]</code> before this step, it becomes <code>[<u><strong>2</strong></u>,1,<u><strong>4</strong></u>,3]</code> after. The values at even indices <code>0</code> and <code>2</code> are sorted in non-decreasing order.</li>
-	</ul>
-	</li>
-</ol>
-
-<p>Return <em>the array formed after rearranging the values of</em> <code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,1,2,3]
-<strong>Output:</strong> [2,3,4,1]
-<strong>Explanation:</strong> 
-First, we sort the values present at odd indices (1 and 3) in non-increasing order.
-So, nums changes from [4,<strong><u>1</u></strong>,2,<strong><u>3</u></strong>] to [4,<u><strong>3</strong></u>,2,<strong><u>1</u></strong>].
-Next, we sort the values present at even indices (0 and 2) in non-decreasing order.
-So, nums changes from [<u><strong>4</strong></u>,1,<strong><u>2</u></strong>,3] to [<u><strong>2</strong></u>,3,<u><strong>4</strong></u>,1].
-Thus, the array formed after rearranging the values is [2,3,4,1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1]
-<strong>Output:</strong> [2,1]
-<strong>Explanation:</strong> 
-Since there is exactly one odd index and one even index, no rearrangement of values takes place.
-The resultant array formed is [2,1], which is the same as the initial array. 
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to separate the elements at odd indices from the elements at even indices.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort the two groups of elements individually.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Combine them to form the resultant array.
-</details>
diff --git a/problems/sort-features-by-popularity/README.md b/problems/sort-features-by-popularity/README.md
deleted file mode 100644
index 6dd77659d..000000000
--- a/problems/sort-features-by-popularity/README.md
+++ /dev/null
@@ -1,31 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximize-palindrome-length-from-subsequences "Maximize Palindrome Length From Subsequences")
-　　　　　　　　　　　　　　　　
-[Next >](../count-items-matching-a-rule "Count Items Matching a Rule")
-
-## [1772. Sort Features by Popularity (Medium)](https://leetcode.com/problems/sort-features-by-popularity "按受欢迎程度排列功能")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a hash map to count the frequency of each word of each string.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the map for sorting the features.
-</details>
diff --git a/problems/sort-integers-by-the-number-of-1-bits/README.md b/problems/sort-integers-by-the-number-of-1-bits/README.md
deleted file mode 100644
index 9ffba5ff0..000000000
--- a/problems/sort-integers-by-the-number-of-1-bits/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../activity-participants "Activity Participants")
-　　　　　　　　　　　　　　　　
-[Next >](../apply-discount-every-n-orders "Apply Discount Every n Orders")
-
-## [1356. Sort Integers by The Number of 1 Bits (Easy)](https://leetcode.com/problems/sort-integers-by-the-number-of-1-bits "根据数字二进制下 1 的数目排序")
-
-<p>You are given an integer array <code>arr</code>. Sort the integers in the array&nbsp;in ascending order by the number of <code>1</code>&#39;s&nbsp;in their binary representation and in case of two or more integers have the same number of <code>1</code>&#39;s you have to sort them in ascending order.</p>
-
-<p>Return <em>the array after sorting it</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [0,1,2,3,4,5,6,7,8]
-<strong>Output:</strong> [0,1,2,4,8,3,5,6,7]
-<strong>Explantion:</strong> [0] is the only integer with 0 bits.
-[1,2,4,8] all have 1 bit.
-[3,5,6] have 2 bits.
-[7] has 3 bits.
-The sorted array by bits is [0,1,2,4,8,3,5,6,7]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1024,512,256,128,64,32,16,8,4,2,1]
-<strong>Output:</strong> [1,2,4,8,16,32,64,128,256,512,1024]
-<strong>Explantion:</strong> All integers have 1 bit in the binary representation, you should just sort them in ascending order.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 500</code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Find Subsequence of Length K With the Largest Sum](../find-subsequence-of-length-k-with-the-largest-sum) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the problem. Count the number of 1's in the binary representation of each integer.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort by the number of 1's ascending and by the value in case of tie.
-</details>
diff --git a/problems/sort-integers-by-the-power-value/README.md b/problems/sort-integers-by-the-power-value/README.md
deleted file mode 100644
index 7a507f22c..000000000
--- a/problems/sort-integers-by-the-power-value/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cinema-seat-allocation "Cinema Seat Allocation")
-　　　　　　　　　　　　　　　　
-[Next >](../pizza-with-3n-slices "Pizza With 3n Slices")
-
-## [1387. Sort Integers by The Power Value (Medium)](https://leetcode.com/problems/sort-integers-by-the-power-value "将整数按权重排序")
-
-<p>The power of an integer <code>x</code> is defined as the number of steps needed to transform <code>x</code> into <code>1</code> using the following steps:</p>
-
-<ul>
-	<li>if <code>x</code> is even then <code>x = x / 2</code></li>
-	<li>if <code>x</code> is odd then <code>x = 3 * x + 1</code></li>
-</ul>
-
-<p>For example, the power of <code>x = 3</code> is <code>7</code> because <code>3</code> needs <code>7</code> steps to become <code>1</code> (<code>3 --&gt; 10 --&gt; 5 --&gt; 16 --&gt; 8 --&gt; 4 --&gt; 2 --&gt; 1</code>).</p>
-
-<p>Given three integers <code>lo</code>, <code>hi</code> and <code>k</code>. The task is to sort all integers in the interval <code>[lo, hi]</code> by the power value in <strong>ascending order</strong>, if two or more integers have <strong>the same</strong> power value sort them by <strong>ascending order</strong>.</p>
-
-<p>Return the <code>k<sup>th</sup></code> integer in the range <code>[lo, hi]</code> sorted by the power value.</p>
-
-<p>Notice that for any integer <code>x</code> <code>(lo &lt;= x &lt;= hi)</code> it is <strong>guaranteed</strong> that <code>x</code> will transform into <code>1</code> using these steps and that the power of <code>x</code> is will <strong>fit</strong> in a 32-bit signed integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> lo = 12, hi = 15, k = 2
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> The power of 12 is 9 (12 --&gt; 6 --&gt; 3 --&gt; 10 --&gt; 5 --&gt; 16 --&gt; 8 --&gt; 4 --&gt; 2 --&gt; 1)
-The power of 13 is 9
-The power of 14 is 17
-The power of 15 is 17
-The interval sorted by the power value [12,13,14,15]. For k = 2 answer is the second element which is 13.
-Notice that 12 and 13 have the same power value and we sorted them in ascending order. Same for 14 and 15.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> lo = 7, hi = 11, k = 4
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> The power array corresponding to the interval [7, 8, 9, 10, 11] is [16, 3, 19, 6, 14].
-The interval sorted by power is [8, 10, 11, 7, 9].
-The fourth number in the sorted array is 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= lo &lt;= hi &lt;= 1000</code></li>
-	<li><code>1 &lt;= k &lt;= hi - lo + 1</code></li>
-</ul>
-
-### Related Topics
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming to get the power of each integer of the intervals.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort all the integers of the interval by the power value and return the k-th in the sorted list.
-</details>
diff --git a/problems/sort-items-by-groups-respecting-dependencies/README.md b/problems/sort-items-by-groups-respecting-dependencies/README.md
deleted file mode 100644
index f6a849031..000000000
--- a/problems/sort-items-by-groups-respecting-dependencies/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-string-with-swaps "Smallest String With Swaps")
-　　　　　　　　　　　　　　　　
-[Next >](../last-person-to-fit-in-the-bus "Last Person to Fit in the Bus")
-
-## [1203. Sort Items by Groups Respecting Dependencies (Hard)](https://leetcode.com/problems/sort-items-by-groups-respecting-dependencies "项目管理")
-
-<p>There are&nbsp;<code>n</code>&nbsp;items each&nbsp;belonging to zero or one of&nbsp;<code>m</code>&nbsp;groups where <code>group[i]</code>&nbsp;is the group that the <code>i</code>-th item belongs to and it&#39;s equal to <code>-1</code>&nbsp;if the <code>i</code>-th item belongs to no group. The items and the groups are zero indexed. A group can have no item belonging to it.</p>
-
-<p>Return a sorted list of the items such that:</p>
-
-<ul>
-	<li>The items that belong to the same group are next to each other in the sorted list.</li>
-	<li>There are some&nbsp;relations&nbsp;between these items where&nbsp;<code>beforeItems[i]</code>&nbsp;is a list containing all the items that should come before the&nbsp;<code>i</code>-th item in the sorted array (to the left of the&nbsp;<code>i</code>-th item).</li>
-</ul>
-
-<p>Return any solution if there is more than one solution and return an <strong>empty list</strong>&nbsp;if there is no solution.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/09/11/1359_ex1.png" style="width: 191px; height: 181px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> n = 8, m = 2, group = [-1,-1,1,0,0,1,0,-1], beforeItems = [[],[6],[5],[6],[3,6],[],[],[]]
-<strong>Output:</strong> [6,3,4,1,5,2,0,7]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 8, m = 2, group = [-1,-1,1,0,0,1,0,-1], beforeItems = [[],[6],[5],[6],[3],[],[4],[]]
-<strong>Output:</strong> []
-<strong>Explanation:</strong>&nbsp;This is the same as example 1 except that 4 needs to be before 6 in the sorted list.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m &lt;= n &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>group.length == beforeItems.length == n</code></li>
-	<li><code>-1 &lt;= group[i] &lt;= m - 1</code></li>
-	<li><code>0 &lt;= beforeItems[i].length &lt;= n - 1</code></li>
-	<li><code>0 &lt;= beforeItems[i][j] &lt;= n - 1</code></li>
-	<li><code>i != beforeItems[i][j]</code></li>
-	<li><code>beforeItems[i]&nbsp;</code>does not contain&nbsp;duplicates elements.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think of it as a graph problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We need to find a topological order on the dependency graph.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Build two graphs, one for the groups and another for the items.
-</details>
diff --git a/problems/sort-linked-list-already-sorted-using-absolute-values/README.md b/problems/sort-linked-list-already-sorted-using-absolute-values/README.md
deleted file mode 100644
index 452636892..000000000
--- a/problems/sort-linked-list-already-sorted-using-absolute-values/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../second-minimum-time-to-reach-destination "Second Minimum Time to Reach Destination")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-valid-words-in-a-sentence "Number of Valid Words in a Sentence")
-
-## [2046. Sort Linked List Already Sorted Using Absolute Values (Medium)](https://leetcode.com/problems/sort-linked-list-already-sorted-using-absolute-values "给按照绝对值排序的链表排序")
-
-
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The nodes with positive values are already in the correct order.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Nodes with negative values need to be moved to the front.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Nodes with negative values are in reversed order.
-</details>
diff --git a/problems/sort-list/README.md b/problems/sort-list/README.md
deleted file mode 100644
index 123c2e962..000000000
--- a/problems/sort-list/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../insertion-sort-list "Insertion Sort List")
-　　　　　　　　　　　　　　　　
-[Next >](../max-points-on-a-line "Max Points on a Line")
-
-## [148. Sort List (Medium)](https://leetcode.com/problems/sort-list "排序链表")
-
-<p>Given the <code>head</code> of a linked list, return <em>the list after sorting it in <strong>ascending order</strong></em>.</p>
-
-<p><strong>Follow up:</strong> Can you sort the linked list in <code>O(n logn)</code> time and <code>O(1)</code>&nbsp;memory (i.e. constant space)?</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/14/sort_list_1.jpg" style="width: 450px; height: 194px;" />
-<pre>
-<strong>Input:</strong> head = [4,2,1,3]
-<strong>Output:</strong> [1,2,3,4]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/14/sort_list_2.jpg" style="width: 550px; height: 184px;" />
-<pre>
-<strong>Input:</strong> head = [-1,5,3,4,0]
-<strong>Output:</strong> [-1,0,3,4,5]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = []
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[0, 5 * 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Merge Sort](../../tag/merge-sort/README.md)]
-
-### Similar Questions
-  1. [Merge Two Sorted Lists](../merge-two-sorted-lists) (Easy)
-  1. [Sort Colors](../sort-colors) (Medium)
-  1. [Insertion Sort List](../insertion-sort-list) (Medium)
diff --git a/problems/sort-list/sort_list.go b/problems/sort-list/sort_list.go
deleted file mode 100644
index 5d1a575c7..000000000
--- a/problems/sort-list/sort_list.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem148
diff --git a/problems/sort-list/sort_list_test.go b/problems/sort-list/sort_list_test.go
deleted file mode 100644
index 5d1a575c7..000000000
--- a/problems/sort-list/sort_list_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem148
diff --git a/problems/sort-the-matrix-diagonally/README.md b/problems/sort-the-matrix-diagonally/README.md
deleted file mode 100644
index 2105b4213..000000000
--- a/problems/sort-the-matrix-diagonally/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../break-a-palindrome "Break a Palindrome")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-subarray-to-maximize-array-value "Reverse Subarray To Maximize Array Value")
-
-## [1329. Sort the Matrix Diagonally (Medium)](https://leetcode.com/problems/sort-the-matrix-diagonally "将矩阵按对角线排序")
-
-<p>A <strong>matrix diagonal</strong> is a diagonal line of cells starting from some cell in either the topmost row or leftmost column and going in the bottom-right direction until reaching the matrix&#39;s end. For example, the <strong>matrix diagonal</strong> starting from <code>mat[2][0]</code>, where <code>mat</code> is a <code>6 x 3</code> matrix, includes cells <code>mat[2][0]</code>, <code>mat[3][1]</code>, and <code>mat[4][2]</code>.</p>
-
-<p>Given an <code>m x n</code> matrix <code>mat</code> of integers, sort each <strong>matrix diagonal</strong> in ascending order and return <em>the resulting matrix</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/01/21/1482_example_1_2.png" style="width: 500px; height: 198px;" />
-<pre>
-<strong>Input:</strong> mat = [[3,3,1,1],[2,2,1,2],[1,1,1,2]]
-<strong>Output:</strong> [[1,1,1,1],[1,2,2,2],[1,2,3,3]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = [[11,25,66,1,69,7],[23,55,17,45,15,52],[75,31,36,44,58,8],[22,27,33,25,68,4],[84,28,14,11,5,50]]
-<strong>Output:</strong> [[5,17,4,1,52,7],[11,11,25,45,8,69],[14,23,25,44,58,15],[22,27,31,36,50,66],[84,28,75,33,55,68]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li><code>1 &lt;= mat[i][j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a data structure to store all values of each diagonal.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How to index the data structure with the id of the diagonal?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-All cells in the same diagonal (i,j) have the same difference so we can get the diagonal of a cell using the difference i-j.
-</details>
diff --git a/problems/sort-transformed-array/README.md b/problems/sort-transformed-array/README.md
deleted file mode 100644
index 6135d7d68..000000000
--- a/problems/sort-transformed-array/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../logger-rate-limiter "Logger Rate Limiter")
-　　　　　　　　　　　　　　　　
-[Next >](../bomb-enemy "Bomb Enemy")
-
-## [360. Sort Transformed Array (Medium)](https://leetcode.com/problems/sort-transformed-array "有序转化数组")
-
-<p>Given a <b>sorted</b> array of integers <i>nums</i> and integer values <i>a</i>, <i>b</i> and <i>c</i>. Apply a quadratic function of the form f(<i>x</i>) = <i>ax</i><sup>2</sup> + <i>bx</i> + <i>c</i> to each element <i>x</i> in the array.</p>
-
-<p>The returned array must be in <b>sorted order</b>.</p>
-
-<p>Expected time complexity: <b>O(<i>n</i>)</b></p>
-
-<div>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>nums = <span id="example-input-1-1">[-4,-2,2,4]</span>, a = <span id="example-input-1-2">1</span>, b = <span id="example-input-1-3">3</span>, c = <span id="example-input-1-4">5</span>
-<strong>Output: </strong><span id="example-output-1">[3,9,15,33]</span>
-</pre>
-
-<div>
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>nums = <span id="example-input-2-1">[-4,-2,2,4]</span>, a = <span id="example-input-2-2">-1</span>, b = <span id="example-input-2-3">3</span>, c = <span id="example-input-2-4">5</span>
-<strong>Output: </strong><span id="example-output-2">[-23,-5,1,7]</span>
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Squares of a Sorted Array](../squares-of-a-sorted-array) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-x^2 + x  will form a parabola.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Parameter A in:  A * x^2 + B * x + C dictates the shape of the parabola.</br>
-Positive A means the parabola remains concave (high-low-high), but negative A inverts the parabola to be convex (low-high-low).
-</details>
diff --git a/problems/sort-transformed-array/sort_transformed_array.go b/problems/sort-transformed-array/sort_transformed_array.go
deleted file mode 100644
index 66db8b48e..000000000
--- a/problems/sort-transformed-array/sort_transformed_array.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem360
diff --git a/problems/sort-transformed-array/sort_transformed_array_test.go b/problems/sort-transformed-array/sort_transformed_array_test.go
deleted file mode 100644
index 66db8b48e..000000000
--- a/problems/sort-transformed-array/sort_transformed_array_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem360
diff --git a/problems/sorting-the-sentence/README.md b/problems/sorting-the-sentence/README.md
deleted file mode 100644
index 8f696c17d..000000000
--- a/problems/sorting-the-sentence/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-word-with-all-prefixes "Longest Word With All Prefixes")
-　　　　　　　　　　　　　　　　
-[Next >](../incremental-memory-leak "Incremental Memory Leak")
-
-## [1859. Sorting the Sentence (Easy)](https://leetcode.com/problems/sorting-the-sentence "将句子排序")
-
-<p>A <strong>sentence</strong> is a list of words that are separated by a single space with no leading or trailing spaces. Each word consists of lowercase and uppercase English letters.</p>
-
-<p>A sentence can be <strong>shuffled</strong> by appending the <strong>1-indexed word position</strong> to each word then rearranging the words in the sentence.</p>
-
-<ul>
-	<li>For example, the sentence <code>&quot;This is a sentence&quot;</code> can be shuffled as <code>&quot;sentence4 a3 is2 This1&quot;</code> or <code>&quot;is2 sentence4 This1 a3&quot;</code>.</li>
-</ul>
-
-<p>Given a <strong>shuffled sentence</strong> <code>s</code> containing no more than <code>9</code> words, reconstruct and return <em>the original sentence</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;is2 sentence4 This1 a3&quot;
-<strong>Output:</strong> &quot;This is a sentence&quot;
-<strong>Explanation:</strong> Sort the words in s to their original positions &quot;This1 is2 a3 sentence4&quot;, then remove the numbers.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;Myself2 Me1 I4 and3&quot;
-<strong>Output:</strong> &quot;Me Myself and I&quot;
-<strong>Explanation:</strong> Sort the words in s to their original positions &quot;Me1 Myself2 and3 I4&quot;, then remove the numbers.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= s.length &lt;= 200</code></li>
-	<li><code>s</code> consists of lowercase and uppercase English letters, spaces, and digits from <code>1</code> to <code>9</code>.</li>
-	<li>The number of words in <code>s</code> is between <code>1</code> and <code>9</code>.</li>
-	<li>The words in <code>s</code> are separated by a single space.</li>
-	<li><code>s</code> contains no leading or trailing spaces.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Check if Numbers Are Ascending in a Sentence](../check-if-numbers-are-ascending-in-a-sentence) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Divide the string into the words as an array of strings
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort the words by removing the last character from each word and sorting according to it
-</details>
diff --git a/problems/soup-servings/README.md b/problems/soup-servings/README.md
deleted file mode 100644
index f49525fb8..000000000
--- a/problems/soup-servings/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-increase-to-keep-city-skyline "Max Increase to Keep City Skyline")
-　　　　　　　　　　　　　　　　
-[Next >](../expressive-words "Expressive Words")
-
-## [808. Soup Servings (Medium)](https://leetcode.com/problems/soup-servings "分汤")
-
-<p>There are two types of soup: <strong>type A</strong> and <strong>type B</strong>. Initially, we have <code>n</code> ml of each type of soup. There are four kinds of operations:</p>
-
-<ol>
-	<li>Serve <code>100</code> ml of <strong>soup A</strong> and <code>0</code> ml of <strong>soup B</strong>,</li>
-	<li>Serve <code>75</code> ml of <strong>soup A</strong> and <code>25</code> ml of <strong>soup B</strong>,</li>
-	<li>Serve <code>50</code> ml of <strong>soup A</strong> and <code>50</code> ml of <strong>soup B</strong>, and</li>
-	<li>Serve <code>25</code> ml of <strong>soup A</strong> and <code>75</code> ml of <strong>soup B</strong>.</li>
-</ol>
-
-<p>When we serve some soup, we give it to someone, and we no longer have it. Each turn, we will choose from the four operations with an equal probability <code>0.25</code>. If the remaining volume of soup is not enough to complete the operation, we will serve as much as possible. We stop once we no longer have some quantity of both types of soup.</p>
-
-<p><strong>Note</strong> that we do not have an operation where all <code>100</code> ml&#39;s of <strong>soup B</strong> are used first.</p>
-
-<p>Return <em>the probability that <strong>soup A</strong> will be empty first, plus half the probability that <strong>A</strong> and <strong>B</strong> become empty at the same time</em>. Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 50
-<strong>Output:</strong> 0.62500
-<strong>Explanation:</strong> If we choose the first two operations, A will become empty first.
-For the third operation, A and B will become empty at the same time.
-For the fourth operation, B will become empty first.
-So the total probability of A becoming empty first plus half the probability that A and B become empty at the same time, is 0.25 * (1 + 1 + 0.5 + 0) = 0.625.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 100
-<strong>Output:</strong> 0.71875
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Probability and Statistics](../../tag/probability-and-statistics/README.md)]
diff --git a/problems/soup-servings/soup_servings.go b/problems/soup-servings/soup_servings.go
deleted file mode 100644
index e58a62aee..000000000
--- a/problems/soup-servings/soup_servings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem808
diff --git a/problems/soup-servings/soup_servings_test.go b/problems/soup-servings/soup_servings_test.go
deleted file mode 100644
index e58a62aee..000000000
--- a/problems/soup-servings/soup_servings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem808
diff --git a/problems/sparse-matrix-multiplication/README.md b/problems/sparse-matrix-multiplication/README.md
deleted file mode 100644
index 3656b4858..000000000
--- a/problems/sparse-matrix-multiplication/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-height-trees "Minimum Height Trees")
-　　　　　　　　　　　　　　　　
-[Next >](../burst-balloons "Burst Balloons")
-
-## [311. Sparse Matrix Multiplication (Medium)](https://leetcode.com/problems/sparse-matrix-multiplication "稀疏矩阵的乘法")
-
-<p>Given two <a href="https://en.wikipedia.org/wiki/Sparse_matrix" target="_blank">sparse matrices</a> <b>A</b> and <b>B</b>, return the result of <b>AB</b>.</p>
-
-<p>You may assume that <b>A</b>&#39;s column number is equal to <b>B</b>&#39;s row number.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-<b>Input:
-
-</b><strong>A</strong> = [
-  [ 1, 0, 0],
-  [-1, 0, 3]
-]
-
-<strong>B</strong> = [
-  [ 7, 0, 0 ],
-  [ 0, 0, 0 ],
-  [ 0, 0, 1 ]
-]
-
-<strong>Output:</strong>
-
-     |  1 0 0 |   | 7 0 0 |   |  7 0 0 |
-<b>AB</b> = | -1 0 3 | x | 0 0 0 | = | -7 0 3 |
-                  | 0 0 1 |
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/sparse-matrix-multiplication/sparse_matrix_multiplication.go b/problems/sparse-matrix-multiplication/sparse_matrix_multiplication.go
deleted file mode 100644
index 39919fb1e..000000000
--- a/problems/sparse-matrix-multiplication/sparse_matrix_multiplication.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem311
diff --git a/problems/sparse-matrix-multiplication/sparse_matrix_multiplication_test.go b/problems/sparse-matrix-multiplication/sparse_matrix_multiplication_test.go
deleted file mode 100644
index 39919fb1e..000000000
--- a/problems/sparse-matrix-multiplication/sparse_matrix_multiplication_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem311
diff --git a/problems/special-array-with-x-elements-greater-than-or-equal-x/README.md b/problems/special-array-with-x-elements-greater-than-or-equal-x/README.md
deleted file mode 100644
index acdb00777..000000000
--- a/problems/special-array-with-x-elements-greater-than-or-equal-x/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sellers-with-no-sales "Sellers With No Sales")
-　　　　　　　　　　　　　　　　
-[Next >](../even-odd-tree "Even Odd Tree")
-
-## [1608. Special Array With X Elements Greater Than or Equal X (Easy)](https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x "特殊数组的特征值")
-
-<p>You are given an array <code>nums</code> of non-negative integers. <code>nums</code> is considered <strong>special</strong> if there exists a number <code>x</code> such that there are <strong>exactly</strong> <code>x</code> numbers in <code>nums</code> that are <strong>greater than or equal to</strong> <code>x</code>.</p>
-
-<p>Notice that <code>x</code> <strong>does not</strong> have to be an element in <code>nums</code>.</p>
-
-<p>Return <code>x</code> <em>if the array is <strong>special</strong>, otherwise, return </em><code>-1</code>. It can be proven that if <code>nums</code> is special, the value for <code>x</code> is <strong>unique</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,5]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are 2 values (3 and 5) that are greater than or equal to 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> No numbers fit the criteria for x.
-If x = 0, there should be 0 numbers &gt;= x, but there are 2.
-If x = 1, there should be 1 number &gt;= x, but there are 0.
-If x = 2, there should be 2 numbers &gt;= x, but there are 0.
-x cannot be greater since there are only 2 numbers in nums.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,4,3,0,4]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> There are 3 values that are greater than or equal to 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Count the number of elements greater than or equal to x for each x in the range [0, nums.length].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If for any x, the condition satisfies, return that x. Otherwise, there is no answer.
-</details>
diff --git a/problems/special-binary-string/README.md b/problems/special-binary-string/README.md
deleted file mode 100644
index e28a06e4e..000000000
--- a/problems/special-binary-string/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-anagram-mappings "Find Anagram Mappings")
-　　　　　　　　　　　　　　　　
-[Next >](../prime-number-of-set-bits-in-binary-representation "Prime Number of Set Bits in Binary Representation")
-
-## [761. Special Binary String (Hard)](https://leetcode.com/problems/special-binary-string "特殊的二进制序列")
-
-<p><strong>Special binary strings</strong> are binary strings with the following two properties:</p>
-
-<ul>
-	<li>The number of <code>0</code>&#39;s is equal to the number of <code>1</code>&#39;s.</li>
-	<li>Every prefix of the binary string has at least as many <code>1</code>&#39;s as <code>0</code>&#39;s.</li>
-</ul>
-
-<p>You are given a <strong>special binary</strong> string <code>s</code>.</p>
-
-<p>A move consists of choosing two consecutive, non-empty, special substrings of <code>s</code>, and swapping them. Two strings are consecutive if the last character of the first string is exactly one index before the first character of the second string.</p>
-
-<p>Return <em>the lexicographically largest resulting string possible after applying the mentioned operations on the string</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;11011000&quot;
-<strong>Output:</strong> &quot;11100100&quot;
-<strong>Explanation:</strong> The strings &quot;10&quot; [occuring at s[1]] and &quot;1100&quot; [at s[3]] are swapped.
-This is the lexicographically largest string possible after some number of swaps.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;10&quot;
-<strong>Output:</strong> &quot;10&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 50</code></li>
-	<li><code>s[i]</code> is either <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
-	<li><code>s</code> is a special binary string.</li>
-</ul>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Valid Parenthesis String](../valid-parenthesis-string) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Draw a line from (x, y) to (x+1, y+1) if we see a "1", else to (x+1, y-1).
-A special substring is just a line that starts and ends at the same y-coordinate, and that is the lowest y-coordinate reached.
-Call a mountain a special substring with no special prefixes - ie. only at the beginning and end is the lowest y-coordinate reached.
-If F is the answer function, and S has mountain decomposition M1,M2,M3,...,Mk,  then the answer is:
-reverse_sorted(F(M1), F(M2), ..., F(Mk)).
-However, you'll also need to deal with the case that S is a mountain, such as 11011000 -> 11100100.
-</details>
diff --git a/problems/special-binary-string/special_binary_string.go b/problems/special-binary-string/special_binary_string.go
deleted file mode 100644
index 9d5c817d0..000000000
--- a/problems/special-binary-string/special_binary_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem761
diff --git a/problems/special-binary-string/special_binary_string_test.go b/problems/special-binary-string/special_binary_string_test.go
deleted file mode 100644
index 9d5c817d0..000000000
--- a/problems/special-binary-string/special_binary_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem761
diff --git a/problems/special-positions-in-a-binary-matrix/README.md b/problems/special-positions-in-a-binary-matrix/README.md
deleted file mode 100644
index 3f8fe5cdd..000000000
--- a/problems/special-positions-in-a-binary-matrix/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../customer-who-visited-but-did-not-make-any-transactions "Customer Who Visited but Did Not Make Any Transactions")
-　　　　　　　　　　　　　　　　
-[Next >](../count-unhappy-friends "Count Unhappy Friends")
-
-## [1582. Special Positions in a Binary Matrix (Easy)](https://leetcode.com/problems/special-positions-in-a-binary-matrix "二进制矩阵中的特殊位置")
-
-<p>Given an <code>m x n</code> binary matrix <code>mat</code>, return <em>the number of special positions in </em><code>mat</code><em>.</em></p>
-
-<p>A position <code>(i, j)</code> is called <strong>special</strong> if <code>mat[i][j] == 1</code> and all other elements in row <code>i</code> and column <code>j</code> are <code>0</code> (rows and columns are <strong>0-indexed</strong>).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/23/special1.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> mat = [[1,0,0],[0,0,1],[1,0,0]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> (1, 2) is a special position because mat[1][2] == 1 and all other elements in row 1 and column 2 are 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/24/special-grid.jpg" style="width: 244px; height: 245px;" />
-<pre>
-<strong>Input:</strong> mat = [[1,0,0],[0,1,0],[0,0,1]]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> (0, 0), (1, 1) and (2, 2) are special positions.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li><code>mat[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep track of 1s in each row and in each column. Then while iterating over matrix, if the current position is 1 and current row as well as current column contains exactly one occurrence of 1.
-</details>
diff --git a/problems/spiral-matrix-ii/README.md b/problems/spiral-matrix-ii/README.md
deleted file mode 100644
index a9f9ed6c2..000000000
--- a/problems/spiral-matrix-ii/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../length-of-last-word "Length of Last Word")
-　　　　　　　　　　　　　　　　
-[Next >](../permutation-sequence "Permutation Sequence")
-
-## [59. Spiral Matrix II (Medium)](https://leetcode.com/problems/spiral-matrix-ii "螺旋矩阵 II")
-
-<p>Given a positive integer <code>n</code>, generate an <code>n x n</code> <code>matrix</code> filled with elements from <code>1</code> to <code>n<sup>2</sup></code> in spiral order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/spiraln.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> [[1,2,3],[8,9,4],[7,6,5]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> [[1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 20</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Spiral Matrix](../spiral-matrix) (Medium)
diff --git a/problems/spiral-matrix-ii/spiral_matrix_ii.go b/problems/spiral-matrix-ii/spiral_matrix_ii.go
deleted file mode 100644
index 6b46f06b9..000000000
--- a/problems/spiral-matrix-ii/spiral_matrix_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem59
diff --git a/problems/spiral-matrix-ii/spiral_matrix_ii_test.go b/problems/spiral-matrix-ii/spiral_matrix_ii_test.go
deleted file mode 100644
index 6b46f06b9..000000000
--- a/problems/spiral-matrix-ii/spiral_matrix_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem59
diff --git a/problems/spiral-matrix-iii/README.md b/problems/spiral-matrix-iii/README.md
deleted file mode 100644
index 51bdcf795..000000000
--- a/problems/spiral-matrix-iii/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../uncommon-words-from-two-sentences "Uncommon Words from Two Sentences")
-　　　　　　　　　　　　　　　　
-[Next >](../possible-bipartition "Possible Bipartition")
-
-## [885. Spiral Matrix III (Medium)](https://leetcode.com/problems/spiral-matrix-iii "螺旋矩阵 III")
-
-<p>You start at the cell <code>(rStart, cStart)</code> of an <code>rows x cols</code> grid facing east. The northwest corner is at the first row and column in the grid, and the southeast corner is at the last row and column.</p>
-
-<p>You will walk in a clockwise spiral shape to visit every position in this grid. Whenever you move outside the grid&#39;s boundary, we continue our walk outside the grid (but may return to the grid boundary later.). Eventually, we reach all <code>rows * cols</code> spaces of the grid.</p>
-
-<p>Return <em>an array of coordinates representing the positions of the grid in the order you visited them</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/08/24/example_1.png" style="width: 174px; height: 99px;" />
-<pre>
-<strong>Input:</strong> rows = 1, cols = 4, rStart = 0, cStart = 0
-<strong>Output:</strong> [[0,0],[0,1],[0,2],[0,3]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/08/24/example_2.png" style="width: 202px; height: 142px;" />
-<pre>
-<strong>Input:</strong> rows = 5, cols = 6, rStart = 1, cStart = 4
-<strong>Output:</strong> [[1,4],[1,5],[2,5],[2,4],[2,3],[1,3],[0,3],[0,4],[0,5],[3,5],[3,4],[3,3],[3,2],[2,2],[1,2],[0,2],[4,5],[4,4],[4,3],[4,2],[4,1],[3,1],[2,1],[1,1],[0,1],[4,0],[3,0],[2,0],[1,0],[0,0]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rows, cols &lt;= 100</code></li>
-	<li><code>0 &lt;= rStart &lt; rows</code></li>
-	<li><code>0 &lt;= cStart &lt; cols</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/spiral-matrix-iii/spiral_matrix_iii.go b/problems/spiral-matrix-iii/spiral_matrix_iii.go
deleted file mode 100644
index bb7e4bc45..000000000
--- a/problems/spiral-matrix-iii/spiral_matrix_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem885
diff --git a/problems/spiral-matrix-iii/spiral_matrix_iii_test.go b/problems/spiral-matrix-iii/spiral_matrix_iii_test.go
deleted file mode 100644
index bb7e4bc45..000000000
--- a/problems/spiral-matrix-iii/spiral_matrix_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem885
diff --git a/problems/spiral-matrix/README.md b/problems/spiral-matrix/README.md
deleted file mode 100644
index 90e6207f2..000000000
--- a/problems/spiral-matrix/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-subarray "Maximum Subarray")
-　　　　　　　　　　　　　　　　
-[Next >](../jump-game "Jump Game")
-
-## [54. Spiral Matrix (Medium)](https://leetcode.com/problems/spiral-matrix "螺旋矩阵")
-
-<p>Given an <code>m x n</code> <code>matrix</code>, return <em>all elements of the</em> <code>matrix</code> <em>in spiral order</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/spiral1.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,2,3],[4,5,6],[7,8,9]]
-<strong>Output:</strong> [1,2,3,6,9,8,7,4,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/spiral.jpg" style="width: 322px; height: 242px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
-<strong>Output:</strong> [1,2,3,4,8,12,11,10,9,5,6,7]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 10</code></li>
-	<li><code>-100 &lt;= matrix[i][j] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Spiral Matrix II](../spiral-matrix-ii) (Medium)
-  1. [Spiral Matrix III](../spiral-matrix-iii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Well for some problems, the best way really is to come up with some algorithms for simulation. Basically, you need to simulate what the problem asks us to do.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We go boundary by boundary and move inwards. That is the essential operation. First row, last column, last row, first column and then we move inwards by 1 and then repeat. That's all, that is all the simulation that we need.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Think about when you want to switch the progress on one of the indexes. If you progress on <pre>i</pre> out of <pre>[i, j]</pre>, you'd be shifting in the same column. Similarly, by changing values for <pre>j</pre>, you'd be shifting in the same row.
-Also, keep track of the end of a boundary so that you can move inwards and then keep repeating. It's always best to run the simulation on edge cases like a single column or a single row to see if anything breaks or not.
-</details>
diff --git a/problems/spiral-matrix/spiral_matrix.go b/problems/spiral-matrix/spiral_matrix.go
deleted file mode 100644
index 501b6c4d3..000000000
--- a/problems/spiral-matrix/spiral_matrix.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem54
diff --git a/problems/spiral-matrix/spiral_matrix_test.go b/problems/spiral-matrix/spiral_matrix_test.go
deleted file mode 100644
index 501b6c4d3..000000000
--- a/problems/spiral-matrix/spiral_matrix_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem54
diff --git a/problems/split-a-string-in-balanced-strings/README.md b/problems/split-a-string-in-balanced-strings/README.md
deleted file mode 100644
index e2cb832da..000000000
--- a/problems/split-a-string-in-balanced-strings/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-vowels-permutation "Count Vowels Permutation")
-　　　　　　　　　　　　　　　　
-[Next >](../queens-that-can-attack-the-king "Queens That Can Attack the King")
-
-## [1221. Split a String in Balanced Strings (Easy)](https://leetcode.com/problems/split-a-string-in-balanced-strings "分割平衡字符串")
-
-<p><strong>Balanced</strong> strings are those that have an equal quantity of <code>&#39;L&#39;</code> and <code>&#39;R&#39;</code> characters.</p>
-
-<p>Given a <strong>balanced</strong> string <code>s</code>, split it in the maximum amount of balanced strings.</p>
-
-<p>Return <em>the maximum amount of split <strong>balanced</strong> strings</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;RLRRLLRLRL&quot;
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>s can be split into &quot;RL&quot;, &quot;RRLL&quot;, &quot;RL&quot;, &quot;RL&quot;, each substring contains same number of &#39;L&#39; and &#39;R&#39;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;RLLLLRRRLR&quot;
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>s can be split into &quot;RL&quot;, &quot;LLLRRR&quot;, &quot;LR&quot;, each substring contains same number of &#39;L&#39; and &#39;R&#39;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;LLLLRRRR&quot;
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>s can be split into &quot;LLLLRRRR&quot;.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;RLRRRLLRLL&quot;
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>s can be split into &quot;RL&quot;, &quot;RRRLLRLL&quot;, since each substring contains an equal number of &#39;L&#39; and &#39;R&#39;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s[i]</code> is either <code>&#39;L&#39;</code> or <code>&#39;R&#39;</code>.</li>
-	<li><code>s</code> is a <strong>balanced</strong> string.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Loop from left to right maintaining a balance variable when it gets an L increase it by one otherwise decrease it by one.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Whenever the balance variable reaches zero then we increase the answer by one.
-</details>
diff --git a/problems/split-a-string-in-balanced-strings/split_a_string_in_balanced_strings.go b/problems/split-a-string-in-balanced-strings/split_a_string_in_balanced_strings.go
deleted file mode 100644
index 6ab2766b8..000000000
--- a/problems/split-a-string-in-balanced-strings/split_a_string_in_balanced_strings.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem1221
-
-func balancedStringSplit(s string) int {
-	ans, flag := 0, 0
-	for _, b := range s {
-		if b == 'L' {
-			flag--
-		} else {
-			flag++
-		}
-		if flag == 0 {
-			ans++
-		}
-	}
-	return ans
-}
diff --git a/problems/split-a-string-in-balanced-strings/split_a_string_in_balanced_strings_test.go b/problems/split-a-string-in-balanced-strings/split_a_string_in_balanced_strings_test.go
deleted file mode 100644
index 7094dc22e..000000000
--- a/problems/split-a-string-in-balanced-strings/split_a_string_in_balanced_strings_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem1221
-
-import "testing"
-
-type testType struct {
-	in   string
-	want int
-}
-
-func TestBalancedStringSplit(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "RLRRLLRLRL",
-			want: 4,
-		},
-		{
-			in:   "RLLLLRRRLR",
-			want: 3,
-		},
-		{
-			in:   "LLLLRRRR",
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := balancedStringSplit(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/split-a-string-into-the-max-number-of-unique-substrings/README.md b/problems/split-a-string-into-the-max-number-of-unique-substrings/README.md
deleted file mode 100644
index 1bdc20e26..000000000
--- a/problems/split-a-string-into-the-max-number-of-unique-substrings/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rearrange-spaces-between-words "Rearrange Spaces Between Words")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-non-negative-product-in-a-matrix "Maximum Non Negative Product in a Matrix")
-
-## [1593. Split a String Into the Max Number of Unique Substrings (Medium)](https://leetcode.com/problems/split-a-string-into-the-max-number-of-unique-substrings "拆分字符串使唯一子字符串的数目最大")
-
-<p>Given a string&nbsp;<code>s</code><var>,</var>&nbsp;return <em>the maximum&nbsp;number of unique substrings that the given string can be split into</em>.</p>
-
-<p>You can split string&nbsp;<code>s</code> into any list of&nbsp;<strong>non-empty substrings</strong>, where the concatenation of the substrings forms the original string.&nbsp;However, you must split the substrings such that all of them are <strong>unique</strong>.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;ababccc&quot;
-<strong>Output:</strong> 5
-<strong>Explanation</strong>: One way to split maximally is [&#39;a&#39;, &#39;b&#39;, &#39;ab&#39;, &#39;c&#39;, &#39;cc&#39;]. Splitting like [&#39;a&#39;, &#39;b&#39;, &#39;a&#39;, &#39;b&#39;, &#39;c&#39;, &#39;cc&#39;] is not valid as you have &#39;a&#39; and &#39;b&#39; multiple times.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aba&quot;
-<strong>Output:</strong> 2
-<strong>Explanation</strong>: One way to split maximally is [&#39;a&#39;, &#39;ba&#39;].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aa&quot;
-<strong>Output:</strong> 1
-<strong>Explanation</strong>: It is impossible to split the string any further.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>
-	<p><code>1 &lt;= s.length&nbsp;&lt;= 16</code></p>
-	</li>
-	<li>
-	<p><code>s</code> contains&nbsp;only lower case English letters.</p>
-	</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a set to keep track of which substrings have been used already
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try each possible substring at every position and backtrack if a complete split is not possible
-</details>
diff --git a/problems/split-array-into-consecutive-subsequences/README.md b/problems/split-array-into-consecutive-subsequences/README.md
deleted file mode 100644
index 26dc3b3e0..000000000
--- a/problems/split-array-into-consecutive-subsequences/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-k-closest-elements "Find K Closest Elements")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-9 "Remove 9")
-
-## [659. Split Array into Consecutive Subsequences (Medium)](https://leetcode.com/problems/split-array-into-consecutive-subsequences "分割数组为连续子序列")
-
-<p>You are given an integer array <code>nums</code> that is <strong>sorted in non-decreasing order</strong>.</p>
-
-<p>Determine if it is possible to split <code>nums</code> into <strong>one or more subsequences</strong> such that <strong>both</strong> of the following conditions are true:</p>
-
-<ul>
-	<li>Each subsequence is a <strong>consecutive increasing sequence</strong> (i.e. each integer is <strong>exactly one</strong> more than the previous integer).</li>
-	<li>All subsequences have a length of <code>3</code><strong> or more</strong>.</li>
-</ul>
-
-<p>Return <code>true</code><em> if you can split </em><code>nums</code><em> according to the above conditions, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>A <strong>subsequence</strong> of an array is a new array that is formed from the original array by deleting some (can be none) of the elements without disturbing the relative positions of the remaining elements. (i.e., <code>[1,3,5]</code> is a subsequence of <code>[<u>1</u>,2,<u>3</u>,4,<u>5</u>]</code> while <code>[1,3,2]</code> is not).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,3,4,5]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> nums can be split into the following subsequences:
-[<strong><u>1</u></strong>,<strong><u>2</u></strong>,<strong><u>3</u></strong>,3,4,5] --&gt; 1, 2, 3
-[1,2,3,<strong><u>3</u></strong>,<strong><u>4</u></strong>,<strong><u>5</u></strong>] --&gt; 3, 4, 5
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,3,4,4,5,5]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> nums can be split into the following subsequences:
-[<strong><u>1</u></strong>,<strong><u>2</u></strong>,<strong><u>3</u></strong>,3,<strong><u>4</u></strong>,4,<strong><u>5</u></strong>,5] --&gt; 1, 2, 3, 4, 5
-[1,2,3,<strong><u>3</u></strong>,4,<strong><u>4</u></strong>,5,<strong><u>5</u></strong>] --&gt; 3, 4, 5
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,4,5]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to split nums into consecutive increasing subsequences of length 3 or more.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-1000 &lt;= nums[i] &lt;= 1000</code></li>
-	<li><code>nums</code> is sorted in <strong>non-decreasing</strong> order.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Top K Frequent Elements](../top-k-frequent-elements) (Medium)
diff --git a/problems/split-array-into-consecutive-subsequences/split_array_into_consecutive_subsequences.go b/problems/split-array-into-consecutive-subsequences/split_array_into_consecutive_subsequences.go
deleted file mode 100644
index 835ee8c40..000000000
--- a/problems/split-array-into-consecutive-subsequences/split_array_into_consecutive_subsequences.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem659
diff --git a/problems/split-array-into-consecutive-subsequences/split_array_into_consecutive_subsequences_test.go b/problems/split-array-into-consecutive-subsequences/split_array_into_consecutive_subsequences_test.go
deleted file mode 100644
index 835ee8c40..000000000
--- a/problems/split-array-into-consecutive-subsequences/split_array_into_consecutive_subsequences_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem659
diff --git a/problems/split-array-into-fibonacci-sequence/README.md b/problems/split-array-into-fibonacci-sequence/README.md
deleted file mode 100644
index 1d3c593ce..000000000
--- a/problems/split-array-into-fibonacci-sequence/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../keys-and-rooms "Keys and Rooms")
-　　　　　　　　　　　　　　　　
-[Next >](../guess-the-word "Guess the Word")
-
-## [842. Split Array into Fibonacci Sequence (Medium)](https://leetcode.com/problems/split-array-into-fibonacci-sequence "将数组拆分成斐波那契序列")
-
-<p>You are given a string of digits <code>num</code>, such as <code>&quot;123456579&quot;</code>. We can split it into a Fibonacci-like sequence <code>[123, 456, 579]</code>.</p>
-
-<p>Formally, a <strong>Fibonacci-like</strong> sequence is a list <code>f</code> of non-negative integers such that:</p>
-
-<ul>
-	<li><code>0 &lt;= f[i] &lt; 2<sup>31</sup></code>, (that is, each integer fits in a <strong>32-bit</strong> signed integer type),</li>
-	<li><code>f.length &gt;= 3</code>, and</li>
-	<li><code>f[i] + f[i + 1] == f[i + 2]</code> for all <code>0 &lt;= i &lt; f.length - 2</code>.</li>
-</ul>
-
-<p>Note that when splitting the string into pieces, each piece must not have extra leading zeroes, except if the piece is the number <code>0</code> itself.</p>
-
-<p>Return any Fibonacci-like sequence split from <code>num</code>, or return <code>[]</code> if it cannot be done.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;1101111&quot;
-<strong>Output:</strong> [11,0,11,11]
-<strong>Explanation:</strong> The output [110, 1, 111] would also be accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;112358130&quot;
-<strong>Output:</strong> []
-<strong>Explanation:</strong> The task is impossible.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;0123&quot;
-<strong>Output:</strong> []
-<strong>Explanation:</strong> Leading zeroes are not allowed, so &quot;01&quot;, &quot;2&quot;, &quot;3&quot; is not valid.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num.length &lt;= 200</code></li>
-	<li><code>num</code> contains only digits.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Additive Number](../additive-number) (Medium)
-  1. [Fibonacci Number](../fibonacci-number) (Easy)
diff --git a/problems/split-array-into-fibonacci-sequence/split_array_into_fibonacci_sequence.go b/problems/split-array-into-fibonacci-sequence/split_array_into_fibonacci_sequence.go
deleted file mode 100644
index a147eacc5..000000000
--- a/problems/split-array-into-fibonacci-sequence/split_array_into_fibonacci_sequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem842
diff --git a/problems/split-array-into-fibonacci-sequence/split_array_into_fibonacci_sequence_test.go b/problems/split-array-into-fibonacci-sequence/split_array_into_fibonacci_sequence_test.go
deleted file mode 100644
index a147eacc5..000000000
--- a/problems/split-array-into-fibonacci-sequence/split_array_into_fibonacci_sequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem842
diff --git a/problems/split-array-largest-sum/README.md b/problems/split-array-largest-sum/README.md
deleted file mode 100644
index 7a6494418..000000000
--- a/problems/split-array-largest-sum/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-palindrome "Longest Palindrome")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-unique-word-abbreviation "Minimum Unique Word Abbreviation")
-
-## [410. Split Array Largest Sum (Hard)](https://leetcode.com/problems/split-array-largest-sum "分割数组的最大值")
-
-<p>Given an array <code>nums</code> which consists of non-negative integers and an integer <code>m</code>, you can split the array into <code>m</code> non-empty continuous subarrays.</p>
-
-<p>Write an algorithm to minimize the largest sum among these <code>m</code> subarrays.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,2,5,10,8], m = 2
-<strong>Output:</strong> 18
-<strong>Explanation:</strong>
-There are four ways to split nums into two subarrays.
-The best way is to split it into [7,2,5] and [10,8],
-where the largest sum among the two subarrays is only 18.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5], m = 2
-<strong>Output:</strong> 9
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,4,4], m = 3
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= m &lt;= min(50, nums.length)</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/split-array-largest-sum/split_array_largest_sum.go b/problems/split-array-largest-sum/split_array_largest_sum.go
deleted file mode 100644
index 896e3cb7c..000000000
--- a/problems/split-array-largest-sum/split_array_largest_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem410
diff --git a/problems/split-array-largest-sum/split_array_largest_sum_test.go b/problems/split-array-largest-sum/split_array_largest_sum_test.go
deleted file mode 100644
index 896e3cb7c..000000000
--- a/problems/split-array-largest-sum/split_array_largest_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem410
diff --git a/problems/split-array-with-equal-sum/README.md b/problems/split-array-with-equal-sum/README.md
deleted file mode 100644
index e4b219c6f..000000000
--- a/problems/split-array-with-equal-sum/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-provinces "Number of Provinces")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-longest-consecutive-sequence-ii "Binary Tree Longest Consecutive Sequence II")
-
-## [548. Split Array with Equal Sum (Hard)](https://leetcode.com/problems/split-array-with-equal-sum "将数组分割成和相等的子数组")
-
-<p>
-Given an array with n integers, you need to find if there are triplets  (i, j, k) which satisfies following conditions:
-<ol>
-<li> 0 < i, i + 1 < j, j + 1 < k < n - 1 </li>
-<li> Sum of subarrays (0, i - 1), (i + 1, j - 1), (j + 1, k - 1) and (k + 1, n - 1) should be equal. </li>
-</ol>
-where we define that subarray (L, R) represents a slice of the original array starting from the element indexed L to the element indexed R.
-</p>
-
-<p><b>Example:</b><br />
-<pre>
-<b>Input:</b> [1,2,1,2,1,2,1]
-<b>Output:</b> True
-<b>Explanation:</b>
-i = 1, j = 3, k = 5. 
-sum(0, i - 1) = sum(0, 0) = 1
-sum(i + 1, j - 1) = sum(2, 2) = 1
-sum(j + 1, k - 1) = sum(4, 4) = 1
-sum(k + 1, n - 1) = sum(6, 6) = 1
-</pre>
-</p>
-
-<b>Note:</b>
-<ol>
-<li> 1 <= n <= 2000. </li>
-<li> Elements in the given array will be in range [-1,000,000, 1,000,000]. </li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
diff --git a/problems/split-array-with-equal-sum/split_array_with_equal_sum.go b/problems/split-array-with-equal-sum/split_array_with_equal_sum.go
deleted file mode 100644
index 13e95d169..000000000
--- a/problems/split-array-with-equal-sum/split_array_with_equal_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem548
diff --git a/problems/split-array-with-equal-sum/split_array_with_equal_sum_test.go b/problems/split-array-with-equal-sum/split_array_with_equal_sum_test.go
deleted file mode 100644
index 13e95d169..000000000
--- a/problems/split-array-with-equal-sum/split_array_with_equal_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem548
diff --git a/problems/split-array-with-same-average/README.md b/problems/split-array-with-same-average/README.md
deleted file mode 100644
index f7cfa9d69..000000000
--- a/problems/split-array-with-same-average/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-morse-code-words "Unique Morse Code Words")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-lines-to-write-string "Number of Lines To Write String")
-
-## [805. Split Array With Same Average (Hard)](https://leetcode.com/problems/split-array-with-same-average "数组的均值分割")
-
-<p>You are given an integer array <code>nums</code>.</p>
-
-<p>You should move each element of <code>nums</code> into one of the two arrays <code>A</code> and <code>B</code> such that <code>A</code> and <code>B</code> are non-empty, and <code>average(A) == average(B)</code>.</p>
-
-<p>Return <code>true</code> if it is possible to achieve that and <code>false</code> otherwise.</p>
-
-<p><strong>Note</strong> that for an array <code>arr</code>, <code>average(arr)</code> is the sum of all the elements of <code>arr</code> over the length of <code>arr</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5,6,7,8]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We can split the array into [1,4,5,8] and [2,3,6,7], and both of them have an average of 4.5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,1]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 30</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
diff --git a/problems/split-array-with-same-average/split_array_with_same_average.go b/problems/split-array-with-same-average/split_array_with_same_average.go
deleted file mode 100644
index 5d50da878..000000000
--- a/problems/split-array-with-same-average/split_array_with_same_average.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem805
diff --git a/problems/split-array-with-same-average/split_array_with_same_average_test.go b/problems/split-array-with-same-average/split_array_with_same_average_test.go
deleted file mode 100644
index 5d50da878..000000000
--- a/problems/split-array-with-same-average/split_array_with_same_average_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem805
diff --git a/problems/split-bst/README.md b/problems/split-bst/README.md
deleted file mode 100644
index 143d477ad..000000000
--- a/problems/split-bst/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../global-and-local-inversions "Global and Local Inversions")
-　　　　　　　　　　　　　　　　
-[Next >](../swap-adjacent-in-lr-string "Swap Adjacent in LR String")
-
-## [776. Split BST (Medium)](https://leetcode.com/problems/split-bst "拆分二叉搜索树")
-
-<p>Given a Binary Search Tree (BST) with root node <code>root</code>, and a target value <code>V</code>, split the tree into two subtrees&nbsp;where one subtree has nodes that are all smaller or equal to the target value, while the other subtree has all nodes that are greater than the target value.&nbsp; It&#39;s not necessarily the case that the tree contains a node with value <code>V</code>.</p>
-
-<p>Additionally, most of the structure of the original tree should remain.&nbsp; Formally, for any child C with parent P in the original tree, if they are both in the same subtree after the split, then node C should still have the parent P.</p>
-
-<p>You should output the root TreeNode of&nbsp;both subtrees after splitting, in any order.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [4,2,6,1,3,5,7], V = 2
-<strong>Output:</strong> [[2,1],[4,3,6,null,null,5,7]]
-<strong>Explanation:</strong>
-Note that root, output[0], and output[1] are TreeNode objects, not arrays.
-
-The given tree [4,2,6,1,3,5,7] is represented by the following diagram:
-
-          4
-        /   \
-      2      6
-     / \    / \
-    1   3  5   7
-
-while the diagrams for the outputs are:
-
-          4
-        /   \
-      3      6      and    2
-            / \           /
-           5   7         1
-</pre>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>The size of the BST will not exceed <code>50</code>.</li>
-	<li>The BST is always valid and each node&#39;s value is different.</li>
-</ol>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Delete Node in a BST](../delete-node-in-a-bst) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use recursion.  If root.val <= V, you split root.right into two halves, then join it's left half back on root.right.
-</details>
diff --git a/problems/split-bst/split_bst.go b/problems/split-bst/split_bst.go
deleted file mode 100644
index 1f648eaef..000000000
--- a/problems/split-bst/split_bst.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem776
diff --git a/problems/split-bst/split_bst_test.go b/problems/split-bst/split_bst_test.go
deleted file mode 100644
index 1f648eaef..000000000
--- a/problems/split-bst/split_bst_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem776
diff --git a/problems/split-concatenated-strings/README.md b/problems/split-concatenated-strings/README.md
deleted file mode 100644
index ebca547de..000000000
--- a/problems/split-concatenated-strings/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../brick-wall "Brick Wall")
-　　　　　　　　　　　　　　　　
-[Next >](../next-greater-element-iii "Next Greater Element III")
-
-## [555. Split Concatenated Strings (Medium)](https://leetcode.com/problems/split-concatenated-strings "分割连接字符串")
-
-<p>Given a list of strings, you could concatenate these strings together into a loop, where for each string you could choose to reverse it or not. Among all the possible loops, you need to find the lexicographically biggest string after cutting the loop, which will make the looped string into a regular one.</p>
-
-<p>Specifically, to find the lexicographically biggest string, you need to experience two phases: 
-<ol>
-<li>Concatenate all the strings into a loop, where you can reverse some strings or not and connect them in the same order as given.</li>
-<li>Cut and make one breakpoint in any place of the loop, which will make the looped string into a regular one starting from the character at the cutpoint. </li>
-</ol>
-</p>
-
-<p>And your job is to find the lexicographically biggest one among all the possible regular strings.</p>
-
-
-<p><b>Example:</b><br />
-<pre>
-<b>Input:</b> "abc", "xyz"
-<b>Output:</b> "zyxcba"
-<b>Explanation:</b> You can get the looped string "-abcxyz-", "-abczyx-", "-cbaxyz-", "-cbazyx-", <br/>where '-' represents the looped status. <br/>The answer string came from the fourth looped one, <br/>where you could cut from the middle character 'a' and get "zyxcba".
-</pre>
-</p>
-
-<p><b>Note:</b><br>
-<ol>
-<li>The input strings will only contain lowercase letters.</li>
-<li>The total length of all the strings will not over 1,000.</li>
-</ol>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
diff --git a/problems/split-concatenated-strings/split_concatenated_strings.go b/problems/split-concatenated-strings/split_concatenated_strings.go
deleted file mode 100644
index 55812cee8..000000000
--- a/problems/split-concatenated-strings/split_concatenated_strings.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem555
diff --git a/problems/split-concatenated-strings/split_concatenated_strings_test.go b/problems/split-concatenated-strings/split_concatenated_strings_test.go
deleted file mode 100644
index 55812cee8..000000000
--- a/problems/split-concatenated-strings/split_concatenated_strings_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem555
diff --git a/problems/split-linked-list-in-parts/README.md b/problems/split-linked-list-in-parts/README.md
deleted file mode 100644
index ab8deab44..000000000
--- a/problems/split-linked-list-in-parts/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-pivot-index "Find Pivot Index")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-atoms "Number of Atoms")
-
-## [725. Split Linked List in Parts (Medium)](https://leetcode.com/problems/split-linked-list-in-parts "分隔链表")
-
-<p>Given the <code>head</code> of a singly linked list and an integer <code>k</code>, split the linked list into <code>k</code> consecutive linked list parts.</p>
-
-<p>The length of each part should be as equal as possible: no two parts should have a size differing by more than one. This may lead to some parts being null.</p>
-
-<p>The parts should be in the order of occurrence in the input list, and parts occurring earlier should always have a size greater than or equal to parts occurring later.</p>
-
-<p>Return <em>an array of the </em><code>k</code><em> parts</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/13/split1-lc.jpg" style="width: 400px; height: 134px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3], k = 5
-<strong>Output:</strong> [[1],[2],[3],[],[]]
-<strong>Explanation:</strong>
-The first element output[0] has output[0].val = 1, output[0].next = null.
-The last element output[4] is null, but its string representation as a ListNode is [].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/13/split2-lc.jpg" style="width: 600px; height: 60px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5,6,7,8,9,10], k = 3
-<strong>Output:</strong> [[1,2,3,4],[5,6,7],[8,9,10]]
-<strong>Explanation:</strong>
-The input has been split into consecutive parts with size difference at most 1, and earlier parts are a larger size than the later parts.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is in the range <code>[0, 1000]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 1000</code></li>
-	<li><code>1 &lt;= k &lt;= 50</code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-
-### Similar Questions
-  1. [Rotate List](../rotate-list) (Medium)
-  1. [Odd Even Linked List](../odd-even-linked-list) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If there are N nodes in the list, and k parts, then every part has N/k elements, except the first N%k parts have an extra one.
-</details>
diff --git a/problems/split-linked-list-in-parts/split_linked_list_in_parts.go b/problems/split-linked-list-in-parts/split_linked_list_in_parts.go
deleted file mode 100644
index 34ab94c88..000000000
--- a/problems/split-linked-list-in-parts/split_linked_list_in_parts.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem725
diff --git a/problems/split-linked-list-in-parts/split_linked_list_in_parts_test.go b/problems/split-linked-list-in-parts/split_linked_list_in_parts_test.go
deleted file mode 100644
index 34ab94c88..000000000
--- a/problems/split-linked-list-in-parts/split_linked_list_in_parts_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem725
diff --git a/problems/split-two-strings-to-make-palindrome/README.md b/problems/split-two-strings-to-make-palindrome/README.md
deleted file mode 100644
index b8a9ef7b2..000000000
--- a/problems/split-two-strings-to-make-palindrome/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximal-network-rank "Maximal Network Rank")
-　　　　　　　　　　　　　　　　
-[Next >](../count-subtrees-with-max-distance-between-cities "Count Subtrees With Max Distance Between Cities")
-
-## [1616. Split Two Strings to Make Palindrome (Medium)](https://leetcode.com/problems/split-two-strings-to-make-palindrome "分割两个字符串得到回文串")
-
-<p>You are given two strings <code>a</code> and <code>b</code> of the same length. Choose an index and split both strings <strong>at the same index</strong>, splitting <code>a</code> into two strings: <code>a<sub>prefix</sub></code> and <code>a<sub>suffix</sub></code> where <code>a = a<sub>prefix</sub> + a<sub>suffix</sub></code>, and splitting <code>b</code> into two strings: <code>b<sub>prefix</sub></code> and <code>b<sub>suffix</sub></code> where <code>b = b<sub>prefix</sub> + b<sub>suffix</sub></code>. Check if <code>a<sub>prefix</sub> + b<sub>suffix</sub></code> or <code>b<sub>prefix</sub> + a<sub>suffix</sub></code> forms a palindrome.</p>
-
-<p>When you split a string <code>s</code> into <code>s<sub>prefix</sub></code> and <code>s<sub>suffix</sub></code>, either <code>s<sub>suffix</sub></code> or <code>s<sub>prefix</sub></code> is allowed to be empty. For example, if <code>s = &quot;abc&quot;</code>, then <code>&quot;&quot; + &quot;abc&quot;</code>, <code>&quot;a&quot; + &quot;bc&quot;</code>, <code>&quot;ab&quot; + &quot;c&quot;</code> , and <code>&quot;abc&quot; + &quot;&quot;</code> are valid splits.</p>
-
-<p>Return <code>true</code><em> if it is possible to form</em><em> a palindrome string, otherwise return </em><code>false</code>.</p>
-
-<p><strong>Notice</strong> that&nbsp;<code>x + y</code> denotes the concatenation of strings <code>x</code> and <code>y</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;x&quot;, b = &quot;y&quot;
-<strong>Output:</strong> true
-<strong>Explaination:</strong> If either a or b are palindromes the answer is true since you can split in the following way:
-a<sub>prefix</sub> = &quot;&quot;, a<sub>suffix</sub> = &quot;x&quot;
-b<sub>prefix</sub> = &quot;&quot;, b<sub>suffix</sub> = &quot;y&quot;
-Then, a<sub>prefix</sub> + b<sub>suffix</sub> = &quot;&quot; + &quot;y&quot; = &quot;y&quot;, which is a palindrome.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;xbdef&quot;, b = &quot;xecab&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = &quot;ulacfd&quot;, b = &quot;jizalu&quot;
-<strong>Output:</strong> true
-<strong>Explaination:</strong> Split them at index 3:
-a<sub>prefix</sub> = &quot;ula&quot;, a<sub>suffix</sub> = &quot;cfd&quot;
-b<sub>prefix</sub> = &quot;jiz&quot;, b<sub>suffix</sub> = &quot;alu&quot;
-Then, a<sub>prefix</sub> + b<sub>suffix</sub> = &quot;ula&quot; + &quot;alu&quot; = &quot;ulaalu&quot;, which is a palindrome.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= a.length, b.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>a.length == b.length</code></li>
-	<li><code>a</code> and <code>b</code> consist of lowercase English letters</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try finding the largest prefix form a that matches a suffix in b
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try string matching
-</details>
diff --git a/problems/splitting-a-string-into-descending-consecutive-values/README.md b/problems/splitting-a-string-into-descending-consecutive-values/README.md
deleted file mode 100644
index 97aca561b..000000000
--- a/problems/splitting-a-string-into-descending-consecutive-values/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-distance-to-the-target-element "Minimum Distance to the Target Element")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-adjacent-swaps-to-reach-the-kth-smallest-number "Minimum Adjacent Swaps to Reach the Kth Smallest Number")
-
-## [1849. Splitting a String Into Descending Consecutive Values (Medium)](https://leetcode.com/problems/splitting-a-string-into-descending-consecutive-values "将字符串拆分为递减的连续值")
-
-<p>You are given a string <code>s</code> that consists of only digits.</p>
-
-<p>Check if we can split <code>s</code> into <strong>two or more non-empty substrings</strong> such that the <strong>numerical values</strong> of the substrings are in <strong>descending order</strong> and the <strong>difference</strong> between numerical values of every two <strong>adjacent</strong> <strong>substrings</strong> is equal to <code>1</code>.</p>
-
-<ul>
-	<li>For example, the string <code>s = &quot;0090089&quot;</code> can be split into <code>[&quot;0090&quot;, &quot;089&quot;]</code> with numerical values <code>[90,89]</code>. The values are in descending order and adjacent values differ by <code>1</code>, so this way is valid.</li>
-	<li>Another example, the string <code>s = &quot;001&quot;</code> can be split into <code>[&quot;0&quot;, &quot;01&quot;]</code>, <code>[&quot;00&quot;, &quot;1&quot;]</code>, or <code>[&quot;0&quot;, &quot;0&quot;, &quot;1&quot;]</code>. However all the ways are invalid because they have numerical values <code>[0,1]</code>, <code>[0,1]</code>, and <code>[0,0,1]</code> respectively, all of which are not in descending order.</li>
-</ul>
-
-<p>Return <code>true</code> <em>if it is possible to split</em> <code>s</code>​​​​​​ <em>as described above</em><em>, or </em><code>false</code><em> otherwise.</em></p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters in a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;1234&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There is no valid way to split s.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;050043&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> s can be split into [&quot;05&quot;, &quot;004&quot;, &quot;3&quot;] with numerical values [5,4,3].
-The values are in descending order with adjacent values differing by 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;9080701&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There is no valid way to split s.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 20</code></li>
-	<li><code>s</code> only consists of digits.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-One solution is to try all possible splits using backtrack
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Look out for trailing zeros in string
-</details>
diff --git a/problems/sqrtx/README.md b/problems/sqrtx/README.md
deleted file mode 100644
index 6fb4dff4a..000000000
--- a/problems/sqrtx/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../text-justification "Text Justification")
-　　　　　　　　　　　　　　　　
-[Next >](../climbing-stairs "Climbing Stairs")
-
-## [69. Sqrt(x) (Easy)](https://leetcode.com/problems/sqrtx "x 的平方根")
-
-<p>Given a non-negative integer <code>x</code>,&nbsp;compute and return <em>the square root of</em> <code>x</code>.</p>
-
-<p>Since the return type&nbsp;is an integer, the decimal digits are <strong>truncated</strong>, and only <strong>the integer part</strong> of the result&nbsp;is returned.</p>
-
-<p><strong>Note:&nbsp;</strong>You are not allowed to use any built-in exponent function or operator, such as <code>pow(x, 0.5)</code> or&nbsp;<code>x ** 0.5</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 4
-<strong>Output:</strong> 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> x = 8
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The square root of 8 is 2.82842..., and since the decimal part is truncated, 2 is returned.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= x &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Pow(x, n)](../powx-n) (Medium)
-  1. [Valid Perfect Square](../valid-perfect-square) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try exploring all integers. (Credits: @annujoshi)
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use the sorted property of integers to reduced the search space. (Credits: @annujoshi)
-</details>
diff --git a/problems/sqrtx/sqrtx.go b/problems/sqrtx/sqrtx.go
deleted file mode 100644
index b03817773..000000000
--- a/problems/sqrtx/sqrtx.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem69
-
-func mySqrt(x int) int {
-	if x < 2 {
-		return x
-	}
-	r := x / 2
-	for r > x/r {
-		r = (r + x/r) / 2
-	}
-	return r
-}
diff --git a/problems/sqrtx/sqrtx_test.go b/problems/sqrtx/sqrtx_test.go
deleted file mode 100644
index 1df7ab5a6..000000000
--- a/problems/sqrtx/sqrtx_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem69
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestMySqrt(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   4,
-			want: 2,
-		},
-		{
-			in:   8,
-			want: 2,
-		},
-		{
-			in:   0,
-			want: 0,
-		},
-		{
-			in:   1,
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := mySqrt(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/squares-of-a-sorted-array/README.md b/problems/squares-of-a-sorted-array/README.md
deleted file mode 100644
index d4c8ef936..000000000
--- a/problems/squares-of-a-sorted-array/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-perimeter-triangle "Largest Perimeter Triangle")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-turbulent-subarray "Longest Turbulent Subarray")
-
-## [977. Squares of a Sorted Array (Easy)](https://leetcode.com/problems/squares-of-a-sorted-array "有序数组的平方")
-
-<p>Given an integer array <code>nums</code> sorted in <strong>non-decreasing</strong> order, return <em>an array of <strong>the squares of each number</strong> sorted in non-decreasing order</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-4,-1,0,3,10]
-<strong>Output:</strong> [0,1,9,16,100]
-<strong>Explanation:</strong> After squaring, the array becomes [16,1,0,9,100].
-After sorting, it becomes [0,1,9,16,100].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-7,-3,2,3,11]
-<strong>Output:</strong> [4,9,9,49,121]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code><span>1 &lt;= nums.length &lt;= </span>10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>nums</code> is sorted in <strong>non-decreasing</strong> order.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Squaring each element and sorting the new array is very trivial, could you find an <code>O(n)</code> solution using a different approach?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Merge Sorted Array](../merge-sorted-array) (Easy)
-  1. [Sort Transformed Array](../sort-transformed-array) (Medium)
diff --git a/problems/squares-of-a-sorted-array/squares_of_a_sorted_array.go b/problems/squares-of-a-sorted-array/squares_of_a_sorted_array.go
deleted file mode 100644
index 31d94d962..000000000
--- a/problems/squares-of-a-sorted-array/squares_of_a_sorted_array.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem977
-
-import "sort"
-
-func sortedSquares(A []int) []int {
-	ans := make([]int, len(A))
-	for i, v := range A {
-		ans[i] = v * v
-	}
-	sort.Ints(ans)
-	return ans
-}
diff --git a/problems/squares-of-a-sorted-array/squares_of_a_sorted_array_test.go b/problems/squares-of-a-sorted-array/squares_of_a_sorted_array_test.go
deleted file mode 100644
index bdfe20889..000000000
--- a/problems/squares-of-a-sorted-array/squares_of_a_sorted_array_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem977
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []int
-	want []int
-}
-
-func TestSortedSquares(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{-4, -1, 0, 3, 10},
-			want: []int{0, 1, 9, 16, 100},
-		},
-		{
-			in:   []int{-7, -3, 2, 3, 11},
-			want: []int{4, 9, 9, 49, 121},
-		},
-	}
-	for _, tt := range tests {
-		got := sortedSquares(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/squirrel-simulation/README.md b/problems/squirrel-simulation/README.md
deleted file mode 100644
index dcb935bcb..000000000
--- a/problems/squirrel-simulation/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subtree-of-another-tree "Subtree of Another Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../winning-candidate "Winning Candidate")
-
-## [573. Squirrel Simulation (Medium)](https://leetcode.com/problems/squirrel-simulation "松鼠模拟")
-
-There&#39;s a tree, a squirrel, and several nuts. Positions are represented by the cells in a 2D grid. Your goal is to find the <b>minimal</b> distance for the squirrel to collect all the nuts and put them under the tree one by one. The squirrel can only take at most <b>one nut</b> at one time and can move in four directions - up, down, left and right, to the adjacent cell. The distance is represented by the number of moves.
-<p><b>Example 1:</b></p>
-
-<pre><b>Input:</b> 
-Height : 5
-Width : 7
-Tree position : [2,2]
-Squirrel : [4,4]
-Nuts : [[3,0], [2,5]]
-<b>Output:</b> 12
-<b>Explanation:</b>
-<img src="https://assets.leetcode.com/uploads/2018/10/22/squirrel_simulation.png" style="width: 40%;" />​​​​​
-</pre>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>All given positions won&#39;t overlap.</li>
-	<li>The squirrel can take at most one nut at one time.</li>
-	<li>The given positions of nuts have no order.</li>
-	<li>Height and width are positive integers. 3 &lt;= height * width &lt;= 10,000.</li>
-	<li>The given positions contain at least one nut, only one tree and one squirrel.</li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Will Brute force solution works here? What will be its complexity?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Brute force definitely won't work here. Think of some simple solution. Take some example and make some observations.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Will order of nuts traversed by squirrel is important or only first nut traversed by squirrel is important?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Are there some paths which squirrel have to cover in any case? If yes, what are they?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Did you notice only first nut traversed by squirrel matters? Obviously squirrel will choose first nut which will result in minimum distance.
-</details>
diff --git a/problems/squirrel-simulation/squirrel_simulation.go b/problems/squirrel-simulation/squirrel_simulation.go
deleted file mode 100644
index 349983d57..000000000
--- a/problems/squirrel-simulation/squirrel_simulation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem573
diff --git a/problems/squirrel-simulation/squirrel_simulation_test.go b/problems/squirrel-simulation/squirrel_simulation_test.go
deleted file mode 100644
index 349983d57..000000000
--- a/problems/squirrel-simulation/squirrel_simulation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem573
diff --git a/problems/stamping-the-grid/README.md b/problems/stamping-the-grid/README.md
deleted file mode 100644
index e11e22239..000000000
--- a/problems/stamping-the-grid/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-palindrome-by-concatenating-two-letter-words "Longest Palindrome by Concatenating Two Letter Words")
-　　　　　　　　　　　　　　　　
-[Next >](../check-if-every-row-and-column-contains-all-numbers "Check if Every Row and Column Contains All Numbers")
-
-## [2132. Stamping the Grid (Hard)](https://leetcode.com/problems/stamping-the-grid "用邮票贴满网格图")
-
-<p>You are given an <code>m x n</code> binary matrix <code>grid</code> where each cell is either <code>0</code> (empty) or <code>1</code> (occupied).</p>
-
-<p>You are then given stamps of size <code>stampHeight x stampWidth</code>. We want to fit the stamps such that they follow the given <strong>restrictions</strong> and <strong>requirements</strong>:</p>
-
-<ol>
-	<li>Cover all the <strong>empty</strong> cells.</li>
-	<li>Do not cover any of the <strong>occupied</strong> cells.</li>
-	<li>We can put as <strong>many</strong> stamps as we want.</li>
-	<li>Stamps can <strong>overlap</strong> with each other.</li>
-	<li>Stamps are not allowed to be <strong>rotated</strong>.</li>
-	<li>Stamps must stay completely <strong>inside</strong> the grid.</li>
-</ol>
-
-<p>Return <code>true</code> <em>if it is possible to fit the stamps while following the given restrictions and requirements. Otherwise, return</em> <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/03/ex1.png" style="width: 180px; height: 237px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,0,0,0],[1,0,0,0],[1,0,0,0],[1,0,0,0],[1,0,0,0]], stampHeight = 4, stampWidth = 3
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We have two overlapping stamps (labeled 1 and 2 in the image) that are able to cover all the empty cells.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/03/ex2.png" style="width: 170px; height: 179px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,0,0,0],[0,1,0,0],[0,0,1,0],[0,0,0,1]], stampHeight = 2, stampWidth = 2 
-<strong>Output:</strong> false 
-<strong>Explanation:</strong> There is no way to fit the stamps onto all the empty cells without the stamps going outside the grid.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[r].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= m * n &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>grid[r][c]</code> is either <code>0</code> or <code>1</code>.</li>
-	<li><code>1 &lt;= stampHeight, stampWidth &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can check if every empty cell is a part of a consecutive row of empty cells that has a width of at least stampWidth as well as a consecutive column of empty cells that has a height of at least stampHeight.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-We can prove that this condition is sufficient and necessary to fit the stamps while following the given restrictions and requirements.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For each row, find every consecutive row of empty cells, and mark all the cells where the consecutive row is at least stampWidth wide. Do the same for the columns with stampHeight. Then, you can check if every cell is marked twice.
-</details>
diff --git a/problems/stamping-the-sequence/README.md b/problems/stamping-the-sequence/README.md
deleted file mode 100644
index 9b995d25d..000000000
--- a/problems/stamping-the-sequence/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../knight-dialer "Knight Dialer")
-　　　　　　　　　　　　　　　　
-[Next >](../reorder-data-in-log-files "Reorder Data in Log Files")
-
-## [936. Stamping The Sequence (Hard)](https://leetcode.com/problems/stamping-the-sequence "戳印序列")
-
-<p>You are given two strings <code>stamp</code> and <code>target</code>. Initially, there is a string <code>s</code> of length <code>target.length</code> with all <code>s[i] == &#39;?&#39;</code>.</p>
-
-<p>In one turn, you can place <code>stamp</code> over <code>s</code> and replace every letter in the <code>s</code> with the corresponding letter from <code>stamp</code>.</p>
-
-<ul>
-	<li>For example, if <code>stamp = &quot;abc&quot;</code> and <code>target = &quot;abcba&quot;</code>, then <code>s</code> is <code>&quot;?????&quot;</code> initially. In one turn you can:
-	<ul>
-		<li>place <code>stamp</code> at index <code>0</code> of <code>s</code> to obtain <code>&quot;abc??&quot;</code>,</li>
-		<li>place <code>stamp</code> at index <code>1</code> of <code>s</code> to obtain <code>&quot;?abc?&quot;</code>, or</li>
-		<li>place <code>stamp</code> at index <code>2</code> of <code>s</code> to obtain <code>&quot;??abc&quot;</code>.</li>
-	</ul>
-	Note that <code>stamp</code> must be fully contained in the boundaries of <code>s</code> in order to stamp (i.e., you cannot place <code>stamp</code> at index <code>3</code> of <code>s</code>).</li>
-</ul>
-
-<p>We want to convert <code>s</code> to <code>target</code> using <strong>at most</strong> <code>10 * target.length</code> turns.</p>
-
-<p>Return <em>an array of the index of the left-most letter being stamped at each turn</em>. If we cannot obtain <code>target</code> from <code>s</code> within <code>10 * target.length</code> turns, return an empty array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stamp = &quot;abc&quot;, target = &quot;ababc&quot;
-<strong>Output:</strong> [0,2]
-<strong>Explanation:</strong> Initially s = &quot;?????&quot;.
-- Place stamp at index 0 to get &quot;abc??&quot;.
-- Place stamp at index 2 to get &quot;ababc&quot;.
-[1,0,2] would also be accepted as an answer, as well as some other answers.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stamp = &quot;abca&quot;, target = &quot;aabcaca&quot;
-<strong>Output:</strong> [3,0,1]
-<strong>Explanation:</strong> Initially s = &quot;???????&quot;.
-- Place stamp at index 3 to get &quot;???abca&quot;.
-- Place stamp at index 0 to get &quot;abcabca&quot;.
-- Place stamp at index 1 to get &quot;aabcaca&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= stamp.length &lt;= target.length &lt;= 1000</code></li>
-	<li><code>stamp</code> and <code>target</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Queue](../../tag/queue/README.md)]
diff --git a/problems/stamping-the-sequence/stamping_the_sequence.go b/problems/stamping-the-sequence/stamping_the_sequence.go
deleted file mode 100644
index 3e6635b20..000000000
--- a/problems/stamping-the-sequence/stamping_the_sequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem936
diff --git a/problems/stamping-the-sequence/stamping_the_sequence_test.go b/problems/stamping-the-sequence/stamping_the_sequence_test.go
deleted file mode 100644
index 3e6635b20..000000000
--- a/problems/stamping-the-sequence/stamping_the_sequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem936
diff --git a/problems/statistics-from-a-large-sample/README.md b/problems/statistics-from-a-large-sample/README.md
deleted file mode 100644
index bb2f741e1..000000000
--- a/problems/statistics-from-a-large-sample/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-common-supersequence "Shortest Common Supersequence ")
-　　　　　　　　　　　　　　　　
-[Next >](../car-pooling "Car Pooling")
-
-## [1093. Statistics from a Large Sample (Medium)](https://leetcode.com/problems/statistics-from-a-large-sample "大样本统计")
-
-<p>You are given a large sample of integers in the range <code>[0, 255]</code>. Since the sample is so large, it is represented by an array <code>count</code>&nbsp;where <code>count[k]</code> is the <strong>number of times</strong> that <code>k</code> appears in the sample.</p>
-
-<p>Calculate the following statistics:</p>
-
-<ul>
-	<li><code>minimum</code>: The minimum element in the sample.</li>
-	<li><code>maximum</code>: The maximum element in the sample.</li>
-	<li><code>mean</code>: The average of the sample, calculated as the total sum of all elements divided by the total number of elements.</li>
-	<li><code>median</code>:
-	<ul>
-		<li>If the sample has an odd number of elements, then the <code>median</code> is the middle element once the sample is sorted.</li>
-		<li>If the sample has an even number of elements, then the <code>median</code> is the average of the two middle elements once the sample is sorted.</li>
-	</ul>
-	</li>
-	<li><code>mode</code>: The number that appears the most in the sample. It is guaranteed to be <strong>unique</strong>.</li>
-</ul>
-
-<p>Return <em>the statistics of the sample as an array of floating-point numbers </em><code>[minimum, maximum, mean, median, mode]</code><em>. Answers within </em><code>10<sup>-5</sup></code><em> of the actual answer will be accepted.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> count = [0,1,3,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
-<strong>Output:</strong> [1.00000,3.00000,2.37500,2.50000,3.00000]
-<strong>Explanation:</strong> The sample represented by count is [1,2,2,2,3,3,3,3].
-The minimum and maximum are 1 and 3 respectively.
-The mean is (1+2+2+2+3+3+3+3) / 8 = 19 / 8 = 2.375.
-Since the size of the sample is even, the median is the average of the two middle elements 2 and 3, which is 2.5.
-The mode is 3 as it appears the most in the sample.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> count = [0,4,3,2,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
-<strong>Output:</strong> [1.00000,4.00000,2.18182,2.00000,1.00000]
-<strong>Explanation:</strong> The sample represented by count is [1,1,1,1,2,2,2,3,3,4,4].
-The minimum and maximum are 1 and 4 respectively.
-The mean is (1+1+1+1+2+2+2+3+3+4+4) / 11 = 24 / 11 = 2.18181818... (for display purposes, the output shows the rounded number 2.18182).
-Since the size of the sample is odd, the median is the middle element 2.
-The mode is 1 as it appears the most in the sample.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>count.length == 256</code></li>
-	<li><code>0 &lt;= count[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= sum(count) &lt;= 10<sup>9</sup></code></li>
-	<li>The mode of the sample that <code>count</code> represents is <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Probability and Statistics](../../tag/probability-and-statistics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The hard part is the median.  Write a helper function which finds the k-th element from the sample.
-</details>
diff --git a/problems/statistics-from-a-large-sample/statistics_from_a_large_sample.go b/problems/statistics-from-a-large-sample/statistics_from_a_large_sample.go
deleted file mode 100644
index c93b75726..000000000
--- a/problems/statistics-from-a-large-sample/statistics_from_a_large_sample.go
+++ /dev/null
@@ -1,86 +0,0 @@
-package problem1093
-
-import "sort"
-
-func sampleStats(count []int) []float64 {
-	return []float64{
-		minimum(count),
-		maximum(count),
-		mean(count),
-		median(count),
-		mode(count),
-	}
-}
-
-// minimum：最小值
-func minimum(count []int) float64 {
-	i := 0
-	for ; i < len(count); i++ {
-		if count[i] != 0 {
-			break
-		}
-	}
-	return float64(i)
-}
-
-// maximum：最大值
-func maximum(count []int) float64 {
-	i := len(count) - 1
-	for ; i >= 0; i-- {
-		if count[i] != 0 {
-			break
-		}
-	}
-	return float64(i)
-}
-
-// mean   ：平均数
-func mean(count []int) float64 {
-	sum, c := 0, 0
-	for i := 0; i < len(count); i++ {
-		if count[i] == 0 {
-			continue
-		}
-		sum += i * count[i]
-		c += count[i]
-	}
-	return float64(sum) / float64(c)
-}
-
-// median ：中位数，排序后，位于正中间的数。
-func median(count []int) float64 {
-	k := make([]int, 0, 256)
-	c := make([]int, 0, 256)
-	sum := 0
-	for i := 0; i < len(count); i++ {
-		if count[i] == 0 {
-			continue
-		}
-		sum += count[i]
-		k = append(k, i)
-		c = append(c, sum)
-	}
-	if sum%2 == 1 {
-		h := sum/2 + 1
-		i := sort.SearchInts(c, h)
-		return float64(k[i])
-	}
-	h := sum / 2
-	i := sort.SearchInts(c, h)
-	j := sort.SearchInts(c, h+1)
-	return float64(k[i]+k[j]) / 2
-}
-
-// mode   ：出现次数最多的数
-func mode(count []int) float64 {
-	k, c := -1, -1
-	for i := 0; i < len(count); i++ {
-		if count[i] == 0 {
-			continue
-		}
-		if c < count[i] {
-			k, c = i, count[i]
-		}
-	}
-	return float64(k)
-}
diff --git a/problems/step-by-step-directions-from-a-binary-tree-node-to-another/README.md b/problems/step-by-step-directions-from-a-binary-tree-node-to-another/README.md
deleted file mode 100644
index ad7f54d10..000000000
--- a/problems/step-by-step-directions-from-a-binary-tree-node-to-another/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-the-middle-node-of-a-linked-list "Delete the Middle Node of a Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-arrangement-of-pairs "Valid Arrangement of Pairs")
-
-## [2096. Step-By-Step Directions From a Binary Tree Node to Another (Medium)](https://leetcode.com/problems/step-by-step-directions-from-a-binary-tree-node-to-another "从二叉树一个节点到另一个节点每一步的方向")
-
-<p>You are given the <code>root</code> of a <strong>binary tree</strong> with <code>n</code> nodes. Each node is uniquely assigned a value from <code>1</code> to <code>n</code>. You are also given an integer <code>startValue</code> representing the value of the start node <code>s</code>, and a different integer <code>destValue</code> representing the value of the destination node <code>t</code>.</p>
-
-<p>Find the <strong>shortest path</strong> starting from node <code>s</code> and ending at node <code>t</code>. Generate step-by-step directions of such path as a string consisting of only the <strong>uppercase</strong> letters <code>&#39;L&#39;</code>, <code>&#39;R&#39;</code>, and <code>&#39;U&#39;</code>. Each letter indicates a specific direction:</p>
-
-<ul>
-	<li><code>&#39;L&#39;</code> means to go from a node to its <strong>left child</strong> node.</li>
-	<li><code>&#39;R&#39;</code> means to go from a node to its <strong>right child</strong> node.</li>
-	<li><code>&#39;U&#39;</code> means to go from a node to its <strong>parent</strong> node.</li>
-</ul>
-
-<p>Return <em>the step-by-step directions of the <strong>shortest path</strong> from node </em><code>s</code><em> to node</em> <code>t</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/15/eg1.png" style="width: 214px; height: 163px;" />
-<pre>
-<strong>Input:</strong> root = [5,1,2,3,null,6,4], startValue = 3, destValue = 6
-<strong>Output:</strong> &quot;UURL&quot;
-<strong>Explanation:</strong> The shortest path is: 3 &rarr; 1 &rarr; 5 &rarr; 2 &rarr; 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/11/15/eg2.png" style="width: 74px; height: 102px;" />
-<pre>
-<strong>Input:</strong> root = [2,1], startValue = 2, destValue = 1
-<strong>Output:</strong> &quot;L&quot;
-<strong>Explanation:</strong> The shortest path is: 2 &rarr; 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is <code>n</code>.</li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= Node.val &lt;= n</code></li>
-	<li>All the values in the tree are <strong>unique</strong>.</li>
-	<li><code>1 &lt;= startValue, destValue &lt;= n</code></li>
-	<li><code>startValue != destValue</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The shortest path between any two nodes in a tree must pass through their Lowest Common Ancestor (LCA). The path will travel upwards from node s to the LCA and then downwards from the LCA to node t.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find the path strings from root → s, and root → t. Can you use these two strings to prepare the final answer?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Remove the longest common prefix of the two path strings to get the path LCA → s, and LCA → t. Each step in the path of LCA → s should be reversed as 'U'.
-</details>
diff --git a/problems/stepping-numbers/README.md b/problems/stepping-numbers/README.md
deleted file mode 100644
index 015aa8167..000000000
--- a/problems/stepping-numbers/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-sum-bsts "Two Sum BSTs")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-palindrome-iii "Valid Palindrome III")
-
-## [1215. Stepping Numbers (Medium)](https://leetcode.com/problems/stepping-numbers "步进数")
-
-<p>A <em>Stepping Number</em> is&nbsp;an integer&nbsp;such that&nbsp;all of its adjacent digits have an absolute difference of exactly <code>1</code>. For example, <code>321</code> is a Stepping Number while <code>421</code> is not.</p>
-
-<p>Given two integers <code>low</code> and <code>high</code>, find and return a <strong>sorted</strong> list of all the Stepping Numbers in the range <code>[low, high]</code>&nbsp;inclusive.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> low = 0, high = 21
-<strong>Output:</strong> [0,1,2,3,4,5,6,7,8,9,10,12,21]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= low &lt;= high &lt;= 2 * 10^9</code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to generate the numbers using recursion.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-In one step in the recursion, add a valid digit to the right of the current number.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Save the number if it's in the range between low and high.
-</details>
diff --git a/problems/stickers-to-spell-word/README.md b/problems/stickers-to-spell-word/README.md
deleted file mode 100644
index 344c35177..000000000
--- a/problems/stickers-to-spell-word/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../employee-importance "Employee Importance")
-　　　　　　　　　　　　　　　　
-[Next >](../top-k-frequent-words "Top K Frequent Words")
-
-## [691. Stickers to Spell Word (Hard)](https://leetcode.com/problems/stickers-to-spell-word "贴纸拼词")
-
-<p>We are given <code>n</code> different types of <code>stickers</code>. Each sticker has a lowercase English word on it.</p>
-
-<p>You would like to spell out the given string <code>target</code> by cutting individual letters from your collection of stickers and rearranging them. You can use each sticker more than once if you want, and you have infinite quantities of each sticker.</p>
-
-<p>Return <em>the minimum number of stickers that you need to spell out </em><code>target</code>. If the task is impossible, return <code>-1</code>.</p>
-
-<p><strong>Note:</strong> In all test cases, all words were chosen randomly from the <code>1000</code> most common US English words, and <code>target</code> was chosen as a concatenation of two random words.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stickers = [&quot;with&quot;,&quot;example&quot;,&quot;science&quot;], target = &quot;thehat&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-We can use 2 &quot;with&quot; stickers, and 1 &quot;example&quot; sticker.
-After cutting and rearrange the letters of those stickers, we can form the target &quot;thehat&quot;.
-Also, this is the minimum number of stickers necessary to form the target string.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stickers = [&quot;notice&quot;,&quot;possible&quot;], target = &quot;basicbasic&quot;
-<strong>Output:</strong> -1
-Explanation:
-We cannot form the target &quot;basicbasic&quot; from cutting letters from the given stickers.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == stickers.length</code></li>
-	<li><code>1 &lt;= n &lt;= 50</code></li>
-	<li><code>1 &lt;= stickers[i].length &lt;= 10</code></li>
-	<li><code>1 &lt;= target &lt;= 15</code></li>
-	<li><code>stickers[i]</code> and <code>target</code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Similar Questions
-  1. [Ransom Note](../ransom-note) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We want to perform an exhaustive search, but we need to speed it up based on the input data being random.  
-
-For all stickers, we can ignore any letters that are not in the target word.  
-
-When our candidate answer won't be smaller than an answer we have already found, we can stop searching this path.  
-
-When a sticker dominates another, we shouldn't include the dominated sticker in our sticker collection.  [Here, we say a sticker `A` dominates `B` if `A.count(letter) >= B.count(letter)` for all letters.]
-</details>
diff --git a/problems/stickers-to-spell-word/stickers_to_spell_word.go b/problems/stickers-to-spell-word/stickers_to_spell_word.go
deleted file mode 100644
index fa30e1e2c..000000000
--- a/problems/stickers-to-spell-word/stickers_to_spell_word.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem691
diff --git a/problems/stickers-to-spell-word/stickers_to_spell_word_test.go b/problems/stickers-to-spell-word/stickers_to_spell_word_test.go
deleted file mode 100644
index fa30e1e2c..000000000
--- a/problems/stickers-to-spell-word/stickers_to_spell_word_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem691
diff --git a/problems/stock-price-fluctuation/README.md b/problems/stock-price-fluctuation/README.md
deleted file mode 100644
index 993eb2005..000000000
--- a/problems/stock-price-fluctuation/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-operations-to-make-a-uni-value-grid "Minimum Operations to Make a Uni-Value Grid")
-　　　　　　　　　　　　　　　　
-[Next >](../partition-array-into-two-arrays-to-minimize-sum-difference "Partition Array Into Two Arrays to Minimize Sum Difference")
-
-## [2034. Stock Price Fluctuation  (Medium)](https://leetcode.com/problems/stock-price-fluctuation "股票价格波动")
-
-<p>You are given a stream of <strong>records</strong> about a particular stock. Each record contains a <strong>timestamp</strong> and the corresponding <strong>price</strong> of the stock at that timestamp.</p>
-
-<p>Unfortunately due to the volatile nature of the stock market, the records do not come in order. Even worse, some records may be incorrect. Another record with the same timestamp may appear later in the stream <strong>correcting</strong> the price of the previous wrong record.</p>
-
-<p>Design an algorithm that:</p>
-
-<ul>
-	<li><strong>Updates</strong> the price of the stock at a particular timestamp, <strong>correcting</strong> the price from any previous records at the timestamp.</li>
-	<li>Finds the <strong>latest price</strong> of the stock based on the current records. The <strong>latest price</strong> is the price at the latest timestamp recorded.</li>
-	<li>Finds the <strong>maximum price</strong> the stock has been based on the current records.</li>
-	<li>Finds the <strong>minimum price</strong> the stock has been based on the current records.</li>
-</ul>
-
-<p>Implement the <code>StockPrice</code> class:</p>
-
-<ul>
-	<li><code>StockPrice()</code> Initializes the object with no price records.</li>
-	<li><code>void update(int timestamp, int price)</code> Updates the <code>price</code> of the stock at the given <code>timestamp</code>.</li>
-	<li><code>int current()</code> Returns the <strong>latest price</strong> of the stock.</li>
-	<li><code>int maximum()</code> Returns the <strong>maximum price</strong> of the stock.</li>
-	<li><code>int minimum()</code> Returns the <strong>minimum price</strong> of the stock.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;StockPrice&quot;, &quot;update&quot;, &quot;update&quot;, &quot;current&quot;, &quot;maximum&quot;, &quot;update&quot;, &quot;maximum&quot;, &quot;update&quot;, &quot;minimum&quot;]
-[[], [1, 10], [2, 5], [], [], [1, 3], [], [4, 2], []]
-<strong>Output</strong>
-[null, null, null, 5, 10, null, 5, null, 2]
-
-<strong>Explanation</strong>
-StockPrice stockPrice = new StockPrice();
-stockPrice.update(1, 10); // Timestamps are [1] with corresponding prices [10].
-stockPrice.update(2, 5);  // Timestamps are [1,2] with corresponding prices [10,5].
-stockPrice.current();     // return 5, the latest timestamp is 2 with the price being 5.
-stockPrice.maximum();     // return 10, the maximum price is 10 at timestamp 1.
-stockPrice.update(1, 3);  // The previous timestamp 1 had the wrong price, so it is updated to 3.
-                          // Timestamps are [1,2] with corresponding prices [3,5].
-stockPrice.maximum();     // return 5, the maximum price is 5 after the correction.
-stockPrice.update(4, 2);  // Timestamps are [1,2,4] with corresponding prices [3,5,2].
-stockPrice.minimum();     // return 2, the minimum price is 2 at timestamp 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= timestamp, price &lt;= 10<sup>9</sup></code></li>
-	<li>At most <code>10<sup>5</sup></code> calls will be made <strong>in total</strong> to <code>update</code>, <code>current</code>, <code>maximum</code>, and <code>minimum</code>.</li>
-	<li><code>current</code>, <code>maximum</code>, and <code>minimum</code> will be called <strong>only after</strong> <code>update</code> has been called <strong>at least once</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How would you solve the problem for offline queries (all queries given at once)?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think about which data structure can help insert and delete the most optimal way.
-</details>
diff --git a/problems/stone-game-ii/README.md b/problems/stone-game-ii/README.md
deleted file mode 100644
index 7a40acc4c..000000000
--- a/problems/stone-game-ii/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-1-bordered-square "Largest 1-Bordered Square")
-　　　　　　　　　　　　　　　　
-[Next >](../user-activity-for-the-past-30-days-i "User Activity for the Past 30 Days I")
-
-## [1140. Stone Game II (Medium)](https://leetcode.com/problems/stone-game-ii "石子游戏 II")
-
-<p>Alice and Bob continue their&nbsp;games with piles of stones.&nbsp; There are a number of&nbsp;piles&nbsp;<strong>arranged in a row</strong>, and each pile has a positive integer number of stones&nbsp;<code>piles[i]</code>.&nbsp; The objective of the game is to end with the most&nbsp;stones.&nbsp;</p>
-
-<p>Alice&nbsp;and Bob take turns, with Alice starting first.&nbsp; Initially, <code>M = 1</code>.</p>
-
-<p>On each player&#39;s turn, that player&nbsp;can take <strong>all the stones</strong> in the <strong>first</strong> <code>X</code> remaining piles, where <code>1 &lt;= X &lt;= 2M</code>.&nbsp; Then, we set&nbsp;<code>M = max(M, X)</code>.</p>
-
-<p>The game continues until all the stones have been taken.</p>
-
-<p>Assuming Alice and Bob play optimally, return the maximum number of stones Alice&nbsp;can get.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [2,7,9,4,4]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong>  If Alice takes one pile at the beginning, Bob takes two piles, then Alice takes 2 piles again. Alice can get 2 + 4 + 4 = 10 piles in total. If Alice takes two piles at the beginning, then Bob can take all three piles left. In this case, Alice get 2 + 7 = 9 piles in total. So we return 10 since it&#39;s larger. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [1,2,3,4,5,100]
-<strong>Output:</strong> 104
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= piles.length &lt;= 100</code></li>
-	<li><code>1 &lt;= piles[i]&nbsp;&lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming: the states are (i, m) for the answer of piles[i:] and that given m.
-</details>
diff --git a/problems/stone-game-iii/README.md b/problems/stone-game-iii/README.md
deleted file mode 100644
index cb4cc8145..000000000
--- a/problems/stone-game-iii/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-happy-string "Longest Happy String")
-　　　　　　　　　　　　　　　　
-[Next >](../top-travellers "Top Travellers")
-
-## [1406. Stone Game III (Hard)](https://leetcode.com/problems/stone-game-iii "石子游戏 III")
-
-<p>Alice and Bob continue their games with piles of stones. There are several stones <strong>arranged in a row</strong>, and each stone has an associated value which is an integer given in the array <code>stoneValue</code>.</p>
-
-<p>Alice and Bob take turns, with Alice starting first. On each player&#39;s turn, that player can take <code>1</code>, <code>2</code>, or <code>3</code> stones from the <strong>first</strong> remaining stones in the row.</p>
-
-<p>The score of each player is the sum of the values of the stones taken. The score of each player is <code>0</code> initially.</p>
-
-<p>The objective of the game is to end with the highest score, and the winner is the player with the highest score and there could be a tie. The game continues until all the stones have been taken.</p>
-
-<p>Assume Alice and Bob <strong>play optimally</strong>.</p>
-
-<p>Return <code>&quot;Alice&quot;</code><em> if Alice will win, </em><code>&quot;Bob&quot;</code><em> if Bob will win, or </em><code>&quot;Tie&quot;</code><em> if they will end the game with the same score</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> values = [1,2,3,7]
-<strong>Output:</strong> &quot;Bob&quot;
-<strong>Explanation:</strong> Alice will always lose. Her best move will be to take three piles and the score become 6. Now the score of Bob is 7 and Bob wins.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> values = [1,2,3,-9]
-<strong>Output:</strong> &quot;Alice&quot;
-<strong>Explanation:</strong> Alice must choose all the three piles at the first move to win and leave Bob with negative score.
-If Alice chooses one pile her score will be 1 and the next move Bob&#39;s score becomes 5. In the next move, Alice will take the pile with value = -9 and lose.
-If Alice chooses two piles her score will be 3 and the next move Bob&#39;s score becomes 3. In the next move, Alice will take the pile with value = -9 and also lose.
-Remember that both play optimally so here Alice will choose the scenario that makes her win.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> values = [1,2,3,6]
-<strong>Output:</strong> &quot;Tie&quot;
-<strong>Explanation:</strong> Alice cannot win this game. She can end the game in a draw if she decided to choose all the first three piles, otherwise she will lose.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= stoneValue.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>-1000 &lt;= stoneValue[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The game can be mapped to minmax game. Alice tries to maximize the total score and Bob tries to minimize it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use dynamic programming to simulate the game. If the total score was 0 the game is "Tie", and if it has positive value then "Alice" wins, otherwise "Bob" wins.
-</details>
diff --git a/problems/stone-game-iv/README.md b/problems/stone-game-iv/README.md
deleted file mode 100644
index e353d2524..000000000
--- a/problems/stone-game-iv/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-difference-between-largest-and-smallest-value-in-three-moves "Minimum Difference Between Largest and Smallest Value in Three Moves")
-　　　　　　　　　　　　　　　　
-[Next >](../customer-order-frequency "Customer Order Frequency")
-
-## [1510. Stone Game IV (Hard)](https://leetcode.com/problems/stone-game-iv "石子游戏 IV")
-
-<p>Alice and Bob take turns playing a game, with Alice starting first.</p>
-
-<p>Initially, there are <code>n</code> stones in a pile. On each player&#39;s turn, that player makes a <em>move</em> consisting of removing <strong>any</strong> non-zero <strong>square number</strong> of stones in the pile.</p>
-
-<p>Also, if a player cannot make a move, he/she loses the game.</p>
-
-<p>Given a positive integer <code>n</code>, return <code>true</code> if and only if Alice wins the game otherwise return <code>false</code>, assuming both players play optimally.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> true
-<strong>Explanation: </strong>Alice can remove 1 stone winning the game because Bob doesn&#39;t have any moves.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> false
-<strong>Explanation: </strong>Alice can only remove 1 stone, after that Bob removes the last one winning the game (2 -&gt; 1 -&gt; 0).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> true
-<strong>Explanation:</strong> n is already a perfect square, Alice can win with one move, removing 4 stones (4 -&gt; 0).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Similar Questions
-  1. [Stone Game V](../stone-game-v) (Hard)
-  1. [Stone Game VI](../stone-game-vi) (Medium)
-  1. [Stone Game VII](../stone-game-vii) (Medium)
-  1. [Stone Game VIII](../stone-game-viii) (Hard)
-  1. [Stone Game IX](../stone-game-ix) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming to keep track of winning and losing states. Given some number of stones, Alice can win if she can force Bob onto a losing state.
-</details>
diff --git a/problems/stone-game-ix/README.md b/problems/stone-game-ix/README.md
deleted file mode 100644
index d3a199649..000000000
--- a/problems/stone-game-ix/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-missing-observations "Find Missing Observations")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-k-length-subsequence-with-occurrences-of-a-letter "Smallest K-Length Subsequence With Occurrences of a Letter")
-
-## [2029. Stone Game IX (Medium)](https://leetcode.com/problems/stone-game-ix "石子游戏 IX")
-
-<p>Alice and Bob continue their games with stones. There is a row of n stones, and each stone has an associated value. You are given an integer array <code>stones</code>, where <code>stones[i]</code> is the <strong>value</strong> of the <code>i<sup>th</sup></code> stone.</p>
-
-<p>Alice and Bob take turns, with <strong>Alice</strong> starting first. On each turn, the player may remove any stone from <code>stones</code>. The player who removes a stone <strong>loses</strong> if the <strong>sum</strong> of the values of <strong>all removed stones</strong> is divisible by <code>3</code>. Bob will win automatically if there are no remaining stones (even if it is Alice&#39;s turn).</p>
-
-<p>Assuming both players play <strong>optimally</strong>, return <code>true</code> <em>if Alice wins and</em> <code>false</code> <em>if Bob wins</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [2,1]
-<strong>Output:</strong> true
-<strong>Explanation:</strong>&nbsp;The game will be played as follows:
-- Turn 1: Alice can remove either stone.
-- Turn 2: Bob removes the remaining stone. 
-The sum of the removed stones is 1 + 2 = 3 and is divisible by 3. Therefore, Bob loses and Alice wins the game.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong>&nbsp;Alice will remove the only stone, and the sum of the values on the removed stones is 2. 
-Since all the stones are removed and the sum of values is not divisible by 3, Bob wins the game.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [5,1,2,4,3]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Bob will always win. One possible way for Bob to win is shown below:
-- Turn 1: Alice can remove the second stone with value 1. Sum of removed stones = 1.
-- Turn 2: Bob removes the fifth stone with value 3. Sum of removed stones = 1 + 3 = 4.
-- Turn 3: Alices removes the fourth stone with value 4. Sum of removed stones = 1 + 3 + 4 = 8.
-- Turn 4: Bob removes the third stone with value 2. Sum of removed stones = 1 + 3 + 4 + 2 = 10.
-- Turn 5: Alice removes the first stone with value 5. Sum of removed stones = 1 + 3 + 4 + 2 + 5 = 15.
-Alice loses the game because the sum of the removed stones (15) is divisible by 3. Bob wins the game.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= stones.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= stones[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There are limited outcomes given the current sum and the stones remaining.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we greedily simulate starting with taking a stone with remainder 1 or 2 divided by 3?
-</details>
diff --git a/problems/stone-game-v/README.md b/problems/stone-game-v/README.md
deleted file mode 100644
index 79aa9c07c..000000000
--- a/problems/stone-game-v/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-latest-group-of-size-m "Find Latest Group of Size M")
-　　　　　　　　　　　　　　　　
-[Next >](../put-boxes-into-the-warehouse-i "Put Boxes Into the Warehouse I")
-
-## [1563. Stone Game V (Hard)](https://leetcode.com/problems/stone-game-v "石子游戏 V")
-
-<p>There are several stones <strong>arranged in a row</strong>, and each stone has an associated value which is an integer given in the array <code>stoneValue</code>.</p>
-
-<p>In each round of the game, Alice divides the row into <strong>two non-empty rows</strong> (i.e. left row and right row), then Bob calculates the value of each row which is the sum of the values of all the stones in this row. Bob throws away the row which has the maximum value, and Alice&#39;s score increases by the value of the remaining row. If the value of the two rows are equal, Bob lets Alice decide which row will be thrown away. The next round starts with the remaining row.</p>
-
-<p>The game ends when there is only <strong>one stone remaining</strong>. Alice&#39;s is initially <strong>zero</strong>.</p>
-
-<p>Return <i>the maximum score that Alice can obtain</i>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stoneValue = [6,2,3,4,5,5]
-<strong>Output:</strong> 18
-<strong>Explanation:</strong> In the first round, Alice divides the row to [6,2,3], [4,5,5]. The left row has the value 11 and the right row has value 14. Bob throws away the right row and Alice&#39;s score is now 11.
-In the second round Alice divides the row to [6], [2,3]. This time Bob throws away the left row and Alice&#39;s score becomes 16 (11 + 5).
-The last round Alice has only one choice to divide the row which is [2], [3]. Bob throws away the right row and Alice&#39;s score is now 18 (16 + 2). The game ends because only one stone is remaining in the row.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stoneValue = [7,7,7,7,7,7,7]
-<strong>Output:</strong> 28
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> stoneValue = [4]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= stoneValue.length &lt;= 500</code></li>
-	<li><code>1 &lt;= stoneValue[i] &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We need to try all possible divisions for the current row to get the max score.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-As calculating all possible divisions will lead us to calculate some sub-problems more than once, we need to think of dynamic programming.
-</details>
diff --git a/problems/stone-game-vi/README.md b/problems/stone-game-vi/README.md
deleted file mode 100644
index 5d868a7e1..000000000
--- a/problems/stone-game-vi/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-absolute-differences-in-a-sorted-array "Sum of Absolute Differences in a Sorted Array")
-　　　　　　　　　　　　　　　　
-[Next >](../delivering-boxes-from-storage-to-ports "Delivering Boxes from Storage to Ports")
-
-## [1686. Stone Game VI (Medium)](https://leetcode.com/problems/stone-game-vi "石子游戏 VI")
-
-<p>Alice and Bob take turns playing a game, with Alice starting first.</p>
-
-<p>There are <code>n</code> stones in a pile. On each player&#39;s turn, they can <strong>remove</strong> a stone from the pile and receive points based on the stone&#39;s value. Alice and Bob may <strong>value the stones differently</strong>.</p>
-
-<p>You are given two integer arrays of length <code>n</code>, <code>aliceValues</code> and <code>bobValues</code>. Each <code>aliceValues[i]</code> and <code>bobValues[i]</code> represents how Alice and Bob, respectively, value the <code>i<sup>th</sup></code> stone.</p>
-
-<p>The winner is the person with the most points after all the stones are chosen. If both players have the same amount of points, the game results in a draw. Both players will play <strong>optimally</strong>.&nbsp;Both players know the other&#39;s values.</p>
-
-<p>Determine the result of the game, and:</p>
-
-<ul>
-	<li>If Alice wins, return <code>1</code>.</li>
-	<li>If Bob wins, return <code>-1</code>.</li>
-	<li>If the game results in a draw, return <code>0</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> aliceValues = [1,3], bobValues = [2,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-If Alice takes stone 1 (0-indexed) first, Alice will receive 3 points.
-Bob can only choose stone 0, and will only receive 2 points.
-Alice wins.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> aliceValues = [1,2], bobValues = [3,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-If Alice takes stone 0, and Bob takes stone 1, they will both have 1 point.
-Draw.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> aliceValues = [2,4,3], bobValues = [1,6,7]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>
-Regardless of how Alice plays, Bob will be able to have more points than Alice.
-For example, if Alice takes stone 1, Bob can take stone 2, and Alice takes stone 0, Alice will have 6 points to Bob&#39;s 7.
-Bob wins.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == aliceValues.length == bobValues.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= aliceValues[i], bobValues[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-When one takes the stone, they not only get the points, but they take them away from the other player too.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Greedily choose the stone with the maximum aliceValues[i] + bobValues[i].
-</details>
diff --git a/problems/stone-game-vii/README.md b/problems/stone-game-vii/README.md
deleted file mode 100644
index 5d1b5878e..000000000
--- a/problems/stone-game-vii/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partitioning-into-minimum-number-of-deci-binary-numbers "Partitioning Into Minimum Number Of Deci-Binary Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-height-by-stacking-cuboids "Maximum Height by Stacking Cuboids ")
-
-## [1690. Stone Game VII (Medium)](https://leetcode.com/problems/stone-game-vii "石子游戏 VII")
-
-<p>Alice and Bob take turns playing a game, with <strong>Alice starting first</strong>.</p>
-
-<p>There are <code>n</code> stones arranged in a row. On each player&#39;s turn, they can <strong>remove</strong> either the leftmost stone or the rightmost stone from the row and receive points equal to the <strong>sum</strong> of the remaining stones&#39; values in the row. The winner is the one with the higher score when there are no stones left to remove.</p>
-
-<p>Bob found that he will always lose this game (poor Bob, he always loses), so he decided to <strong>minimize the score&#39;s difference</strong>. Alice&#39;s goal is to <strong>maximize the difference</strong> in the score.</p>
-
-<p>Given an array of integers <code>stones</code> where <code>stones[i]</code> represents the value of the <code>i<sup>th</sup></code> stone <strong>from the left</strong>, return <em>the <strong>difference</strong> in Alice and Bob&#39;s score if they both play <strong>optimally</strong>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [5,3,1,4,2]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> 
-- Alice removes 2 and gets 5 + 3 + 1 + 4 = 13 points. Alice = 13, Bob = 0, stones = [5,3,1,4].
-- Bob removes 5 and gets 3 + 1 + 4 = 8 points. Alice = 13, Bob = 8, stones = [3,1,4].
-- Alice removes 3 and gets 1 + 4 = 5 points. Alice = 18, Bob = 8, stones = [1,4].
-- Bob removes 1 and gets 4 points. Alice = 18, Bob = 12, stones = [4].
-- Alice removes 4 and gets 0 points. Alice = 18, Bob = 12, stones = [].
-The score difference is 18 - 12 = 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [7,90,5,1,100,10,10,2]
-<strong>Output:</strong> 122</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == stones.length</code></li>
-	<li><code>2 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= stones[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The constraints are small enough for an N^2 solution.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Try using dynamic programming.
-</details>
diff --git a/problems/stone-game-viii/README.md b/problems/stone-game-viii/README.md
deleted file mode 100644
index 5fa74e2c5..000000000
--- a/problems/stone-game-viii/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../jump-game-vii "Jump Game VII")
-　　　　　　　　　　　　　　　　
-[Next >](../calculate-special-bonus "Calculate Special Bonus")
-
-## [1872. Stone Game VIII (Hard)](https://leetcode.com/problems/stone-game-viii "石子游戏 VIII")
-
-<p>Alice and Bob take turns playing a game, with <strong>Alice starting first</strong>.</p>
-
-<p>There are <code>n</code> stones arranged in a row. On each player&#39;s turn, while the number of stones is <strong>more than one</strong>, they will do the following:</p>
-
-<ol>
-	<li>Choose an integer <code>x &gt; 1</code>, and <strong>remove</strong> the leftmost <code>x</code> stones from the row.</li>
-	<li>Add the <strong>sum</strong> of the <strong>removed</strong> stones&#39; values to the player&#39;s score.</li>
-	<li>Place a <strong>new stone</strong>, whose value is equal to that sum, on the left side of the row.</li>
-</ol>
-
-<p>The game stops when <strong>only</strong> <strong>one</strong> stone is left in the row.</p>
-
-<p>The <strong>score difference</strong> between Alice and Bob is <code>(Alice&#39;s score - Bob&#39;s score)</code>. Alice&#39;s goal is to <strong>maximize</strong> the score difference, and Bob&#39;s goal is the <strong>minimize</strong> the score difference.</p>
-
-<p>Given an integer array <code>stones</code> of length <code>n</code> where <code>stones[i]</code> represents the value of the <code>i<sup>th</sup></code> stone <strong>from the left</strong>, return <em>the <strong>score difference</strong> between Alice and Bob if they both play <strong>optimally</strong>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [-1,2,-3,4,-5]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong>
-- Alice removes the first 4 stones, adds (-1) + 2 + (-3) + 4 = 2 to her score, and places a stone of
-  value 2 on the left. stones = [2,-5].
-- Bob removes the first 2 stones, adds 2 + (-5) = -3 to his score, and places a stone of value -3 on
-  the left. stones = [-3].
-The difference between their scores is 2 - (-3) = 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [7,-6,5,10,5,-2,-6]
-<strong>Output:</strong> 13
-<strong>Explanation:</strong>
-- Alice removes all stones, adds 7 + (-6) + 5 + 10 + 5 + (-2) + (-6) = 13 to her score, and places a
-  stone of value 13 on the left. stones = [13].
-The difference between their scores is 13 - 0 = 13.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> stones = [-10,-12]
-<strong>Output:</strong> -22
-<strong>Explanation:</strong>
-- Alice can only make one move, which is to remove both stones. She adds (-10) + (-12) = -22 to her
-  score and places a stone of value -22 on the left. stones = [-22].
-The difference between their scores is (-22) - 0 = -22.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == stones.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= stones[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Let's note that the only thing that matters is how many stones were removed so we can maintain dp[numberOfRemovedStones]
-</details>
-
-<details>
-<summary>Hint 2</summary>
-dp[x] = max(sum of all elements up to y - dp[y]) for all y > x
-</details>
diff --git a/problems/stone-game/README.md b/problems/stone-game/README.md
deleted file mode 100644
index 111b11a47..000000000
--- a/problems/stone-game/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../middle-of-the-linked-list "Middle of the Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../nth-magical-number "Nth Magical Number")
-
-## [877. Stone Game (Medium)](https://leetcode.com/problems/stone-game "石子游戏")
-
-<p>Alice and Bob play a game with piles of stones. There are an <strong>even</strong> number of piles arranged in a row, and each pile has a <strong>positive</strong> integer number of stones <code>piles[i]</code>.</p>
-
-<p>The objective of the game is to end with the most stones. The <strong>total</strong> number of stones across all the piles is <strong>odd</strong>, so there are no ties.</p>
-
-<p>Alice and Bob take turns, with <strong>Alice starting first</strong>. Each turn, a player takes the entire pile of stones either from the <strong>beginning</strong> or from the <strong>end</strong> of the row. This continues until there are no more piles left, at which point the person with the <strong>most stones wins</strong>.</p>
-
-<p>Assuming Alice and Bob play optimally, return <code>true</code><em> if Alice wins the game, or </em><code>false</code><em> if Bob wins</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [5,3,4,5]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 
-Alice starts first, and can only take the first 5 or the last 5.
-Say she takes the first 5, so that the row becomes [3, 4, 5].
-If Bob takes 3, then the board is [4, 5], and Alice takes 5 to win with 10 points.
-If Bob takes the last 5, then the board is [3, 4], and Alice takes 4 to win with 9 points.
-This demonstrated that taking the first 5 was a winning move for Alice, so we return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> piles = [3,7,2,3]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= piles.length &lt;= 500</code></li>
-	<li><code>piles.length</code> is <strong>even</strong>.</li>
-	<li><code>1 &lt;= piles[i] &lt;= 500</code></li>
-	<li><code>sum(piles[i])</code> is <strong>odd</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
diff --git a/problems/stone-game/stone_game.go b/problems/stone-game/stone_game.go
deleted file mode 100644
index bf6d6690d..000000000
--- a/problems/stone-game/stone_game.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package problem877
-
-func stoneGame(piles []int) bool {
-	return true
-}
diff --git a/problems/stone-game/stone_game_test.go b/problems/stone-game/stone_game_test.go
deleted file mode 100644
index 834473a1c..000000000
--- a/problems/stone-game/stone_game_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem877
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestStoneGame(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{5, 3, 4, 5},
-			want: true,
-		},
-		{
-			in:   []int{2, 5, 7, 3},
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := stoneGame(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/strange-printer-ii/README.md b/problems/strange-printer-ii/README.md
deleted file mode 100644
index 4f5b30e03..000000000
--- a/problems/strange-printer-ii/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../make-sum-divisible-by-p "Make Sum Divisible by P")
-　　　　　　　　　　　　　　　　
-[Next >](../rearrange-spaces-between-words "Rearrange Spaces Between Words")
-
-## [1591. Strange Printer II (Hard)](https://leetcode.com/problems/strange-printer-ii "奇怪的打印机 II")
-
-<p>There is a strange printer with the following two special requirements:</p>
-
-<ul>
-	<li>On each turn, the printer will print a solid rectangular pattern of a single color on the grid. This will cover up the existing colors in the rectangle.</li>
-	<li>Once the printer has used a color for the above operation, <strong>the same color cannot be used again</strong>.</li>
-</ul>
-
-<p>You are given a <code>m x n</code> matrix <code>targetGrid</code>, where <code>targetGrid[row][col]</code> is the color in the position <code>(row, col)</code> of the grid.</p>
-
-<p>Return <code>true</code><em> if it is possible to print the matrix </em><code>targetGrid</code><em>,</em><em> otherwise, return </em><code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/23/print1.jpg" style="width: 600px; height: 175px;" />
-<pre>
-<strong>Input:</strong> targetGrid = [[1,1,1,1],[1,2,2,1],[1,2,2,1],[1,1,1,1]]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/12/23/print2.jpg" style="width: 600px; height: 367px;" />
-<pre>
-<strong>Input:</strong> targetGrid = [[1,1,1,1],[1,1,3,3],[1,1,3,4],[5,5,1,4]]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> targetGrid = [[1,2,1],[2,1,2],[1,2,1]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It is impossible to form targetGrid because it is not allowed to print the same color in different turns.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == targetGrid.length</code></li>
-	<li><code>n == targetGrid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 60</code></li>
-	<li><code>1 &lt;= targetGrid[row][col] &lt;= 60</code></li>
-</ul>
-
-### Related Topics
-  [[Graph](../../tag/graph/README.md)]
-  [[Topological Sort](../../tag/topological-sort/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try thinking in reverse. Given the grid, how can you tell if a colour was painted last?
-</details>
diff --git a/problems/strange-printer/README.md b/problems/strange-printer/README.md
deleted file mode 100644
index c94739d6a..000000000
--- a/problems/strange-printer/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../equal-tree-partition "Equal Tree Partition")
-　　　　　　　　　　　　　　　　
-[Next >](../non-decreasing-array "Non-decreasing Array")
-
-## [664. Strange Printer (Hard)](https://leetcode.com/problems/strange-printer "奇怪的打印机")
-
-<p>There is a strange printer with the following two special properties:</p>
-
-<ul>
-	<li>The printer can only print a sequence of <strong>the same character</strong> each time.</li>
-	<li>At each turn, the printer can print new characters starting from and ending at any place and will cover the original existing characters.</li>
-</ul>
-
-<p>Given a string <code>s</code>, return <em>the minimum number of turns the printer needed to print it</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaabbb&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Print &quot;aaa&quot; first and then print &quot;bbb&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aba&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> Print &quot;aaa&quot; first and then print &quot;b&quot; from the second place of the string, which will cover the existing character &#39;a&#39;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Remove Boxes](../remove-boxes) (Hard)
diff --git a/problems/strange-printer/strange_printer.go b/problems/strange-printer/strange_printer.go
deleted file mode 100644
index 10bce2712..000000000
--- a/problems/strange-printer/strange_printer.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem664
diff --git a/problems/strange-printer/strange_printer_test.go b/problems/strange-printer/strange_printer_test.go
deleted file mode 100644
index 10bce2712..000000000
--- a/problems/strange-printer/strange_printer_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem664
diff --git a/problems/stream-of-characters/README.md b/problems/stream-of-characters/README.md
deleted file mode 100644
index 3f297045a..000000000
--- a/problems/stream-of-characters/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-sum-of-two-non-overlapping-subarrays "Maximum Sum of Two Non-Overlapping Subarrays")
-　　　　　　　　　　　　　　　　
-[Next >](../moving-stones-until-consecutive "Moving Stones Until Consecutive")
-
-## [1032. Stream of Characters (Hard)](https://leetcode.com/problems/stream-of-characters "字符流")
-
-<p>Design an algorithm that accepts a stream of characters and checks if a suffix of these characters is a string of a given array of strings <code>words</code>.</p>
-
-<p>For example, if <code>words = [&quot;abc&quot;, &quot;xyz&quot;]</code>&nbsp;and the stream added the four characters (one by one) <code>&#39;a&#39;</code>, <code>&#39;x&#39;</code>, <code>&#39;y&#39;</code>, and <code>&#39;z&#39;</code>, your algorithm should detect that the suffix <code>&quot;xyz&quot;</code> of the characters <code>&quot;axyz&quot;</code> matches <code>&quot;xyz&quot;</code> from <code>words</code>.</p>
-
-<p>Implement the <code>StreamChecker</code> class:</p>
-
-<ul>
-	<li><code>StreamChecker(String[] words)</code> Initializes the object with the strings array <code>words</code>.</li>
-	<li><code>boolean query(char letter)</code> Accepts a new character from the stream and returns <code>true</code> if any non-empty suffix from the stream forms a word that is in <code>words</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;StreamChecker&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;, &quot;query&quot;]
-[[[&quot;cd&quot;, &quot;f&quot;, &quot;kl&quot;]], [&quot;a&quot;], [&quot;b&quot;], [&quot;c&quot;], [&quot;d&quot;], [&quot;e&quot;], [&quot;f&quot;], [&quot;g&quot;], [&quot;h&quot;], [&quot;i&quot;], [&quot;j&quot;], [&quot;k&quot;], [&quot;l&quot;]]
-<strong>Output</strong>
-[null, false, false, false, true, false, true, false, false, false, false, false, true]
-
-<strong>Explanation</strong>
-StreamChecker streamChecker = new StreamChecker([&quot;cd&quot;, &quot;f&quot;, &quot;kl&quot;]);
-streamChecker.query(&quot;a&quot;); // return False
-streamChecker.query(&quot;b&quot;); // return False
-streamChecker.query(&quot;c&quot;); // return False
-streamChecker.query(&quot;d&quot;); // return True, because &#39;cd&#39; is in the wordlist
-streamChecker.query(&quot;e&quot;); // return False
-streamChecker.query(&quot;f&quot;); // return True, because &#39;f&#39; is in the wordlist
-streamChecker.query(&quot;g&quot;); // return False
-streamChecker.query(&quot;h&quot;); // return False
-streamChecker.query(&quot;i&quot;); // return False
-streamChecker.query(&quot;j&quot;); // return False
-streamChecker.query(&quot;k&quot;); // return False
-streamChecker.query(&quot;l&quot;); // return True, because &#39;kl&#39; is in the wordlist
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 2000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 2000</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters.</li>
-	<li><code>letter</code> is a lowercase English letter.</li>
-	<li>At most <code>4 * 10<sup>4</sup></code> calls will be made to query.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Put the words into a trie, and manage a set of pointers within that trie.
-</details>
diff --git a/problems/stream-of-characters/stream_of_characters.go b/problems/stream-of-characters/stream_of_characters.go
deleted file mode 100644
index 3206e00cb..000000000
--- a/problems/stream-of-characters/stream_of_characters.go
+++ /dev/null
@@ -1,63 +0,0 @@
-package problem1032
-
-// StreamChecker check letters
-type StreamChecker struct {
-	trie   *trie
-	stream []int8
-}
-
-// Constructor returns StreamChecker
-func Constructor(words []string) StreamChecker {
-	m := 0
-	t := &trie{}
-	for _, w := range words {
-		m = max(m, len(w))
-		t.insert(w)
-	}
-	return StreamChecker{
-		trie:   t,
-		stream: make([]int8, 0, 1024),
-	}
-}
-
-// Query returns true if letter in words
-func (sc *StreamChecker) Query(letter byte) bool {
-	sc.stream = append(sc.stream, int8(letter-'a'))
-	n, t := len(sc.stream), sc.trie
-	for i := n - 1; i >= 0; i-- {
-		index := sc.stream[i]
-		if t.next[index] == nil {
-			return false
-		}
-		t = t.next[index]
-		if t.isWord {
-			return true
-		}
-	}
-	return false
-}
-
-type trie struct {
-	next   [26]*trie
-	isWord bool
-}
-
-func (t *trie) insert(word string) {
-	n := len(word)
-	// reversely insert
-	for i := n - 1; i >= 0; i-- {
-		index := int(word[i] - 'a')
-		if t.next[index] == nil {
-			t.next[index] = &trie{}
-		}
-		t = t.next[index]
-	}
-	t.isWord = true
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/string-compression-ii/README.md b/problems/string-compression-ii/README.md
deleted file mode 100644
index 5fb6dc2db..000000000
--- a/problems/string-compression-ii/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-good-leaf-nodes-pairs "Number of Good Leaf Nodes Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../the-most-recent-three-orders "The Most Recent Three Orders")
-
-## [1531. String Compression II (Hard)](https://leetcode.com/problems/string-compression-ii "压缩字符串 II")
-
-<p><a href="http://en.wikipedia.org/wiki/Run-length_encoding">Run-length encoding</a> is a string compression method that works by&nbsp;replacing consecutive identical characters (repeated 2 or more times) with the concatenation of the character and the number marking the count of the characters (length of the run). For example, to compress the string&nbsp;<code>&quot;aabccc&quot;</code>&nbsp;we replace <font face="monospace"><code>&quot;aa&quot;</code></font>&nbsp;by&nbsp;<font face="monospace"><code>&quot;a2&quot;</code></font>&nbsp;and replace <font face="monospace"><code>&quot;ccc&quot;</code></font>&nbsp;by&nbsp;<font face="monospace"><code>&quot;c3&quot;</code></font>. Thus the compressed string becomes <font face="monospace"><code>&quot;a2bc3&quot;</code>.</font></p>
-
-<p>Notice that in this problem, we are not adding&nbsp;<code>&#39;1&#39;</code>&nbsp;after single characters.</p>
-
-<p>Given a&nbsp;string <code>s</code>&nbsp;and an integer <code>k</code>. You need to delete <strong>at most</strong>&nbsp;<code>k</code> characters from&nbsp;<code>s</code>&nbsp;such that the run-length encoded version of <code>s</code>&nbsp;has minimum length.</p>
-
-<p>Find the <em>minimum length of the run-length encoded&nbsp;version of </em><code>s</code><em> after deleting at most </em><code>k</code><em> characters</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaabcccd&quot;, k = 2
-<strong>Output:</strong> 4
-<b>Explanation: </b>Compressing s without deleting anything will give us &quot;a3bc3d&quot; of length 6. Deleting any of the characters &#39;a&#39; or &#39;c&#39; would at most decrease the length of the compressed string to 5, for instance delete 2 &#39;a&#39; then we will have s = &quot;abcccd&quot; which compressed is abc3d. Therefore, the optimal way is to delete &#39;b&#39; and &#39;d&#39;, then the compressed version of s will be &quot;a3c3&quot; of length 4.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabbaa&quot;, k = 2
-<strong>Output:</strong> 2
-<b>Explanation: </b>If we delete both &#39;b&#39; characters, the resulting compressed string would be &quot;a4&quot; of length 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aaaaaaaaaaa&quot;, k = 0
-<strong>Output:</strong> 3
-<strong>Explanation: </strong>Since k is zero, we cannot delete anything. The compressed string is &quot;a11&quot; of length 3.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>0 &lt;= k &lt;= s.length</code></li>
-	<li><code>s</code> contains only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use dynamic programming.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The state of the DP can be the current index and the remaining characters to delete.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Having a prefix sum for each character can help you determine for a certain character c in some specific range, how many characters you need to delete to merge all occurrences of c in that range.
-</details>
diff --git a/problems/string-compression/README.md b/problems/string-compression/README.md
deleted file mode 100644
index 5c788f044..000000000
--- a/problems/string-compression/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-all-duplicates-in-an-array "Find All Duplicates in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../sequence-reconstruction "Sequence Reconstruction")
-
-## [443. String Compression (Medium)](https://leetcode.com/problems/string-compression "压缩字符串")
-
-<p>Given an array of characters <code>chars</code>, compress it using the following algorithm:</p>
-
-<p>Begin with an empty string <code>s</code>. For each group of <strong>consecutive repeating characters</strong> in <code>chars</code>:</p>
-
-<ul>
-	<li>If the group&#39;s length is <code>1</code>, append the character to <code>s</code>.</li>
-	<li>Otherwise, append the character followed by the group&#39;s length.</li>
-</ul>
-
-<p>The compressed string <code>s</code> <strong>should not be returned separately</strong>, but instead, be stored <strong>in the input character array <code>chars</code></strong>. Note that group lengths that are <code>10</code> or longer will be split into multiple characters in <code>chars</code>.</p>
-
-<p>After you are done <b>modifying the input array</b>, return <em>the new length of the array</em>.</p>
-You must write an algorithm that uses only constant extra space.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> chars = [&quot;a&quot;,&quot;a&quot;,&quot;b&quot;,&quot;b&quot;,&quot;c&quot;,&quot;c&quot;,&quot;c&quot;]
-<strong>Output:</strong> Return 6, and the first 6 characters of the input array should be: [&quot;a&quot;,&quot;2&quot;,&quot;b&quot;,&quot;2&quot;,&quot;c&quot;,&quot;3&quot;]
-<strong>Explanation:</strong>&nbsp;The groups are &quot;aa&quot;, &quot;bb&quot;, and &quot;ccc&quot;. This compresses to &quot;a2b2c3&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> chars = [&quot;a&quot;]
-<strong>Output:</strong> Return 1, and the first character of the input array should be: [&quot;a&quot;]
-<strong>Explanation:</strong>&nbsp;The only group is &quot;a&quot;, which remains uncompressed since it&#39;s a single character.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> chars = [&quot;a&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;,&quot;b&quot;]
-<strong>Output:</strong> Return 4, and the first 4 characters of the input array should be: [&quot;a&quot;,&quot;b&quot;,&quot;1&quot;,&quot;2&quot;].
-<strong>Explanation:</strong>&nbsp;The groups are &quot;a&quot; and &quot;bbbbbbbbbbbb&quot;. This compresses to &quot;ab12&quot;.</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> chars = [&quot;a&quot;,&quot;a&quot;,&quot;a&quot;,&quot;b&quot;,&quot;b&quot;,&quot;a&quot;,&quot;a&quot;]
-<strong>Output:</strong> Return 6, and the first 6 characters of the input array should be: [&quot;a&quot;,&quot;3&quot;,&quot;b&quot;,&quot;2&quot;,&quot;a&quot;,&quot;2&quot;].
-<strong>Explanation:</strong>&nbsp;The groups are &quot;aaa&quot;, &quot;bb&quot;, and &quot;aa&quot;. This compresses to &quot;a3b2a2&quot;. Note that each group is independent even if two groups have the same character.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= chars.length &lt;= 2000</code></li>
-	<li><code>chars[i]</code> is a lowercase English letter, uppercase English letter, digit, or symbol.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Count and Say](../count-and-say) (Medium)
-  1. [Encode and Decode Strings](../encode-and-decode-strings) (Medium)
-  1. [Design Compressed String Iterator](../design-compressed-string-iterator) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How do you know if you are at the end of a consecutive group of characters?
-</details>
diff --git a/problems/string-compression/string_compression.go b/problems/string-compression/string_compression.go
deleted file mode 100644
index cc8bfc0eb..000000000
--- a/problems/string-compression/string_compression.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem443
-
-import "strconv"
-
-func compress(chars []byte) int {
-	ans, anchor, l := 0, 0, len(chars)
-	for i, c := range chars {
-		if i == l-1 || c != chars[i+1] {
-			chars[ans] = chars[anchor]
-			ans++
-			if i > anchor {
-				for _, n := range strconv.Itoa(i - anchor + 1) {
-					chars[ans] = byte(n)
-					ans++
-				}
-			}
-			anchor = i + 1
-		}
-	}
-	return ans
-}
diff --git a/problems/string-compression/string_compression_test.go b/problems/string-compression/string_compression_test.go
deleted file mode 100644
index c813ef387..000000000
--- a/problems/string-compression/string_compression_test.go
+++ /dev/null
@@ -1,38 +0,0 @@
-package problem443
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []byte
-	want []byte
-}
-
-func TestCompress(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []byte{'a', 'a', 'b', 'b', 'c', 'c', 'c'},
-			want: []byte{'a', '2', 'b', '2', 'c', '3'},
-		},
-		{
-			in:   []byte{'a'},
-			want: []byte{'a'},
-		},
-		{
-			in:   []byte{'a', 'a'},
-			want: []byte{'a', '2'},
-		},
-		{
-			in:   []byte{'a', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b'},
-			want: []byte{'a', 'b', '1', '2'},
-		},
-	}
-	for _, tt := range tests {
-		l := compress(tt.in)
-		if !reflect.DeepEqual(tt.in[:l], tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, l, tt.want)
-		}
-	}
-}
diff --git a/problems/string-matching-in-an-array/README.md b/problems/string-matching-in-an-array/README.md
deleted file mode 100644
index 0465ce113..000000000
--- a/problems/string-matching-in-an-array/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../top-travellers "Top Travellers")
-　　　　　　　　　　　　　　　　
-[Next >](../queries-on-a-permutation-with-key "Queries on a Permutation With Key")
-
-## [1408. String Matching in an Array (Easy)](https://leetcode.com/problems/string-matching-in-an-array "数组中的字符串匹配")
-
-<p>Given an array of string <code>words</code>. Return all strings in <code>words</code> which is substring of another word in <strong>any</strong> order.&nbsp;</p>
-
-<p>String <code>words[i]</code> is substring of <code>words[j]</code>,&nbsp;if&nbsp;can be obtained removing some characters to left and/or right side of <code>words[j]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;mass&quot;,&quot;as&quot;,&quot;hero&quot;,&quot;superhero&quot;]
-<strong>Output:</strong> [&quot;as&quot;,&quot;hero&quot;]
-<strong>Explanation:</strong> &quot;as&quot; is substring of &quot;mass&quot; and &quot;hero&quot; is substring of &quot;superhero&quot;.
-[&quot;hero&quot;,&quot;as&quot;] is also a valid answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;leetcode&quot;,&quot;et&quot;,&quot;code&quot;]
-<strong>Output:</strong> [&quot;et&quot;,&quot;code&quot;]
-<strong>Explanation:</strong> &quot;et&quot;, &quot;code&quot; are substring of &quot;leetcode&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;blue&quot;,&quot;green&quot;,&quot;bu&quot;]
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 100</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 30</code></li>
-	<li><code>words[i]</code> contains only lowercase English letters.</li>
-	<li>It&#39;s <strong>guaranteed</strong>&nbsp;that <code>words[i]</code>&nbsp;will be unique.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Bruteforce to find if one string is substring of another or use KMP algorithm.
-</details>
diff --git a/problems/string-matching-in-an-array/string_matching_in_an_array.go b/problems/string-matching-in-an-array/string_matching_in_an_array.go
deleted file mode 100644
index c39f42ee7..000000000
--- a/problems/string-matching-in-an-array/string_matching_in_an_array.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package problem1408
-
-import "strings"
-
-func stringMatching(words []string) []string {
-	var ans []string
-	for _, word := range words {
-		for _, val := range words {
-			if val != word && strings.Contains(val, word) {
-				ans = append(ans, word)
-				break
-			}
-		}
-	}
-	return ans
-}
diff --git a/problems/string-matching-in-an-array/string_matching_in_an_array_test.go b/problems/string-matching-in-an-array/string_matching_in_an_array_test.go
deleted file mode 100644
index 00659ab4a..000000000
--- a/problems/string-matching-in-an-array/string_matching_in_an_array_test.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package problem1408
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   []string
-	want []string
-}
-
-func TestStringMatching(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []string{"mass", "as", "hero", "superhero"},
-			want: []string{"as", "hero"},
-		},
-		{
-			in:   []string{"leetcode", "et", "code"},
-			want: []string{"et", "code"},
-		},
-		{
-			in:   []string{"blue", "green", "bu"},
-			want: nil,
-		},
-	}
-	for _, tt := range tests {
-		got := stringMatching(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/string-to-integer-atoi/README.md b/problems/string-to-integer-atoi/README.md
deleted file mode 100644
index fc45cb209..000000000
--- a/problems/string-to-integer-atoi/README.md
+++ /dev/null
@@ -1,97 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-integer "Reverse Integer")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-number "Palindrome Number")
-
-## [8. String to Integer (atoi) (Medium)](https://leetcode.com/problems/string-to-integer-atoi "字符串转换整数 (atoi)")
-
-<p>Implement the <code>myAtoi(string s)</code> function, which converts a string to a 32-bit signed integer (similar to C/C++&#39;s <code>atoi</code> function).</p>
-
-<p>The algorithm for <code>myAtoi(string s)</code> is as follows:</p>
-
-<ol>
-	<li>Read in and ignore any leading whitespace.</li>
-	<li>Check if the next character (if not already at the end of the string) is <code>&#39;-&#39;</code> or <code>&#39;+&#39;</code>. Read this character in if it is either. This determines if the final result is negative or positive respectively. Assume the result is positive if neither is present.</li>
-	<li>Read in next the characters until the next non-digit character or the end of the input is reached. The rest of the string is ignored.</li>
-	<li>Convert these digits into an integer (i.e. <code>&quot;123&quot; -&gt; 123</code>, <code>&quot;0032&quot; -&gt; 32</code>). If no digits were read, then the integer is <code>0</code>. Change the sign as necessary (from step 2).</li>
-	<li>If the integer is out of the 32-bit signed integer range <code>[-2<sup>31</sup>, 2<sup>31</sup> - 1]</code>, then clamp the integer so that it remains in the range. Specifically, integers less than <code>-2<sup>31</sup></code> should be clamped to <code>-2<sup>31</sup></code>, and integers greater than <code>2<sup>31</sup> - 1</code> should be clamped to <code>2<sup>31</sup> - 1</code>.</li>
-	<li>Return the integer as the final result.</li>
-</ol>
-
-<p><strong>Note:</strong></p>
-
-<ul>
-	<li>Only the space character <code>&#39; &#39;</code> is considered a whitespace character.</li>
-	<li><strong>Do not ignore</strong> any characters other than the leading whitespace or the rest of the string after the digits.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;42&quot;
-<strong>Output:</strong> 42
-<strong>Explanation:</strong> The underlined characters are what is read in, the caret is the current reader position.
-Step 1: &quot;42&quot; (no characters read because there is no leading whitespace)
-         ^
-Step 2: &quot;42&quot; (no characters read because there is neither a &#39;-&#39; nor &#39;+&#39;)
-         ^
-Step 3: &quot;<u>42</u>&quot; (&quot;42&quot; is read in)
-           ^
-The parsed integer is 42.
-Since 42 is in the range [-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is 42.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;   -42&quot;
-<strong>Output:</strong> -42
-<strong>Explanation:</strong>
-Step 1: &quot;<u>   </u>-42&quot; (leading whitespace is read and ignored)
-            ^
-Step 2: &quot;   <u>-</u>42&quot; (&#39;-&#39; is read, so the result should be negative)
-             ^
-Step 3: &quot;   -<u>42</u>&quot; (&quot;42&quot; is read in)
-               ^
-The parsed integer is -42.
-Since -42 is in the range [-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is -42.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;4193 with words&quot;
-<strong>Output:</strong> 4193
-<strong>Explanation:</strong>
-Step 1: &quot;4193 with words&quot; (no characters read because there is no leading whitespace)
-         ^
-Step 2: &quot;4193 with words&quot; (no characters read because there is neither a &#39;-&#39; nor &#39;+&#39;)
-         ^
-Step 3: &quot;<u>4193</u> with words&quot; (&quot;4193&quot; is read in; reading stops because the next character is a non-digit)
-             ^
-The parsed integer is 4193.
-Since 4193 is in the range [-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is 4193.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length &lt;= 200</code></li>
-	<li><code>s</code> consists of English letters (lower-case and upper-case), digits (<code>0-9</code>), <code>&#39; &#39;</code>, <code>&#39;+&#39;</code>, <code>&#39;-&#39;</code>, and <code>&#39;.&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Reverse Integer](../reverse-integer) (Medium)
-  1. [Valid Number](../valid-number) (Hard)
-  1. [Check if Numbers Are Ascending in a Sentence](../check-if-numbers-are-ascending-in-a-sentence) (Easy)
diff --git a/problems/string-to-integer-atoi/string_to_integer_atoi.go b/problems/string-to-integer-atoi/string_to_integer_atoi.go
deleted file mode 100644
index 11c397dfb..000000000
--- a/problems/string-to-integer-atoi/string_to_integer_atoi.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem8
-
-import (
-	"math"
-	"strconv"
-	"strings"
-	"unicode"
-)
-
-func myAtoi(str string) int {
-	str = strings.TrimSpace(str)
-	prefix := ""
-	if strings.HasPrefix(str, "-") || strings.HasPrefix(str, "+") {
-		prefix = str[0:1]
-		str = str[1:]
-	}
-	i := strings.IndexFunc(str, func(r rune) bool {
-		return !unicode.IsDigit(r)
-	})
-	if i > -1 {
-		str = str[0:i]
-	}
-	r, _ := strconv.Atoi(prefix + str)
-	if r < math.MinInt32 {
-		r = math.MinInt32
-	} else if r > math.MaxInt32 {
-		r = math.MaxInt32
-	}
-	return r
-}
diff --git a/problems/string-to-integer-atoi/string_to_integer_atoi_test.go b/problems/string-to-integer-atoi/string_to_integer_atoi_test.go
deleted file mode 100644
index 3e37dbd11..000000000
--- a/problems/string-to-integer-atoi/string_to_integer_atoi_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem8
-
-import (
-	"math"
-	"testing"
-)
-
-func TestMyAtoi(t *testing.T) {
-	tests := map[string]int{
-		" ":               0,
-		"42":              42,
-		"+123":            123,
-		"+123 +":          123,
-		"++123":           0,
-		" -42 ":           -42,
-		" -123-":          -123,
-		"--321":           0,
-		"4193 with words": 4193,
-		"words and 987":   0,
-		"-91283472332":    math.MinInt32,
-		"9876543210":      math.MaxInt32,
-	}
-
-	for in, want := range tests {
-		got := myAtoi(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/string-transforms-into-another-string/README.md b/problems/string-transforms-into-another-string/README.md
deleted file mode 100644
index 4e1724a91..000000000
--- a/problems/string-transforms-into-another-string/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../analyze-user-website-visit-pattern "Analyze User Website Visit Pattern")
-　　　　　　　　　　　　　　　　
-[Next >](../day-of-the-year "Day of the Year")
-
-## [1153. String Transforms Into Another String (Hard)](https://leetcode.com/problems/string-transforms-into-another-string "字符串转化")
-
-<p>Given two strings <code>str1</code> and <code>str2</code>&nbsp;of the same length, determine whether you can transform <code>str1</code>&nbsp;into <code>str2</code> by doing <strong>zero or more</strong>&nbsp;<em>conversions</em>.</p>
-
-<p>In one conversion you can convert&nbsp;<strong>all</strong> occurrences of one character in <code>str1</code> to&nbsp;<strong>any</strong> other lowercase English character.</p>
-
-<p>Return <code>true</code>&nbsp;if and only if you can transform <code>str1</code> into <code>str2</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>str1 = <span id="example-input-1-1">&quot;aabcc&quot;</span>, str2 = <span id="example-input-1-2">&quot;ccdee&quot;</span>
-<strong>Output: </strong><span id="example-output-1">true</span>
-<strong>Explanation: </strong>Convert &#39;c&#39; to &#39;e&#39; then &#39;b&#39; to &#39;d&#39; then &#39;a&#39; to &#39;c&#39;. Note that the order of conversions matter.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>str1 = <span id="example-input-2-1">&quot;leetcode&quot;</span>, str2 = <span id="example-input-2-2">&quot;codeleet&quot;</span>
-<strong>Output: </strong><span id="example-output-2">false</span>
-<strong>Explanation: </strong>There is no way to transform str1 to str2.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= str1.length == str2.length &lt;= 10^4</code></li>
-	<li>Both <code>str1</code> and <code>str2</code> contain only lowercase English letters.</li>
-</ol>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Model the problem as a graph problem. Add an edge from one character to another if you need to convert between them.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What if one character needs to be converted into more than one character?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-There would be no solution. Thus, every node can have at most one outgoing edge.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-How to process a linked list?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-How to process a cycle?
-</details>
-
-<details>
-<summary>Hint 6</summary>
-What if there is a character with no outgoing edge? You can use it to break all cycles!
-</details>
diff --git a/problems/string-without-aaa-or-bbb/README.md b/problems/string-without-aaa-or-bbb/README.md
deleted file mode 100644
index 1c7037275..000000000
--- a/problems/string-without-aaa-or-bbb/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-for-tickets "Minimum Cost For Tickets")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-even-numbers-after-queries "Sum of Even Numbers After Queries")
-
-## [984. String Without AAA or BBB (Medium)](https://leetcode.com/problems/string-without-aaa-or-bbb "不含 AAA 或 BBB 的字符串")
-
-<p>Given two integers <code>a</code> and <code>b</code>, return <strong>any</strong> string <code>s</code> such that:</p>
-
-<ul>
-	<li><code>s</code> has length <code>a + b</code> and contains exactly <code>a</code> <code>&#39;a&#39;</code> letters, and exactly <code>b</code> <code>&#39;b&#39;</code> letters,</li>
-	<li>The substring <code>&#39;aaa&#39;</code> does not occur in <code>s</code>, and</li>
-	<li>The substring <code>&#39;bbb&#39;</code> does not occur in <code>s</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 1, b = 2
-<strong>Output:</strong> &quot;abb&quot;
-<strong>Explanation:</strong> &quot;abb&quot;, &quot;bab&quot; and &quot;bba&quot; are all correct answers.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> a = 4, b = 1
-<strong>Output:</strong> &quot;aabaa&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= a, b &lt;= 100</code></li>
-	<li>It is guaranteed such an <code>s</code> exists for the given <code>a</code> and <code>b</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/string-without-aaa-or-bbb/string_without_aaa_or_bbb.go b/problems/string-without-aaa-or-bbb/string_without_aaa_or_bbb.go
deleted file mode 100644
index 67e34b083..000000000
--- a/problems/string-without-aaa-or-bbb/string_without_aaa_or_bbb.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem984
-
-func strWithout3a3b(A int, B int) string {
-	str, ac, bc := "", 0, 0
-	for A > 0 || B > 0 {
-		if A > B && ac < 2 || bc == 2 {
-			str += "a"
-			A, ac, bc = A-1, ac+1, 0
-		} else {
-			str += "b"
-			B, ac, bc = B-1, 0, bc+1
-		}
-	}
-	return str
-}
diff --git a/problems/string-without-aaa-or-bbb/string_without_aaa_or_bbb_test.go b/problems/string-without-aaa-or-bbb/string_without_aaa_or_bbb_test.go
deleted file mode 100644
index ad4625d85..000000000
--- a/problems/string-without-aaa-or-bbb/string_without_aaa_or_bbb_test.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package problem984
-
-import "testing"
-
-type testType struct {
-	a    int
-	b    int
-	want string
-}
-
-func TestStrWithout3a3b(t *testing.T) {
-	tests := [...]testType{
-		{
-			a:    6,
-			b:    2,
-			want: "aabaabaa",
-		},
-		{
-			a:    2,
-			b:    6,
-			want: "bbabbabb",
-		},
-		{
-			a:    1,
-			b:    2,
-			want: "bba",
-		},
-		{
-			a:    4,
-			b:    1,
-			want: "aabaa",
-		},
-	}
-	for _, tt := range tests {
-		got := strWithout3a3b(tt.a, tt.b)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.a, tt.b, got, tt.want)
-		}
-	}
-}
diff --git a/problems/strings-differ-by-one-character/README.md b/problems/strings-differ-by-one-character/README.md
deleted file mode 100644
index 497638a14..000000000
--- a/problems/strings-differ-by-one-character/README.md
+++ /dev/null
@@ -1,31 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-days-to-eat-n-oranges "Minimum Number of Days to Eat N Oranges")
-　　　　　　　　　　　　　　　　
-[Next >](../bank-account-summary "Bank Account Summary")
-
-## [1554. Strings Differ by One Character (Medium)](https://leetcode.com/problems/strings-differ-by-one-character "只有一个不同字符的字符串")
-
-
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-BruteForce, check all pairs and verify if they differ in one character. O(n^2 * m) where n is the number of words and m is the length of each string.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-O(m^2 * n), Use hashset, to insert all possible combinations adding a character "*". For example: If dict[i] = "abc", insert ("*bc", "a*c" and "ab*").
-</details>
diff --git a/problems/strobogrammatic-number-ii/README.md b/problems/strobogrammatic-number-ii/README.md
deleted file mode 100644
index b6bd42690..000000000
--- a/problems/strobogrammatic-number-ii/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../strobogrammatic-number "Strobogrammatic Number")
-　　　　　　　　　　　　　　　　
-[Next >](../strobogrammatic-number-iii "Strobogrammatic Number III")
-
-## [247. Strobogrammatic Number II (Medium)](https://leetcode.com/problems/strobogrammatic-number-ii "中心对称数 II")
-
-<p>A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).</p>
-
-<p>Find all strobogrammatic numbers that are of length = n.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-<b>Input:</b>  n = 2
-<b>Output:</b> <code>[&quot;11&quot;,&quot;69&quot;,&quot;88&quot;,&quot;96&quot;]</code>
-</pre>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-
-### Similar Questions
-  1. [Strobogrammatic Number](../strobogrammatic-number) (Easy)
-  1. [Strobogrammatic Number III](../strobogrammatic-number-iii) (Hard)
-  1. [Sum of k-Mirror Numbers](../sum-of-k-mirror-numbers) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try to use recursion and notice that it should recurse with <i>n</i> - 2 instead of <i>n</i> - 1.
-</details>
diff --git a/problems/strobogrammatic-number-ii/strobogrammatic_number_ii.go b/problems/strobogrammatic-number-ii/strobogrammatic_number_ii.go
deleted file mode 100644
index 26ac73433..000000000
--- a/problems/strobogrammatic-number-ii/strobogrammatic_number_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem247
diff --git a/problems/strobogrammatic-number-ii/strobogrammatic_number_ii_test.go b/problems/strobogrammatic-number-ii/strobogrammatic_number_ii_test.go
deleted file mode 100644
index 26ac73433..000000000
--- a/problems/strobogrammatic-number-ii/strobogrammatic_number_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem247
diff --git a/problems/strobogrammatic-number-iii/README.md b/problems/strobogrammatic-number-iii/README.md
deleted file mode 100644
index 6ba33e54b..000000000
--- a/problems/strobogrammatic-number-iii/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../strobogrammatic-number-ii "Strobogrammatic Number II")
-　　　　　　　　　　　　　　　　
-[Next >](../group-shifted-strings "Group Shifted Strings")
-
-## [248. Strobogrammatic Number III (Hard)](https://leetcode.com/problems/strobogrammatic-number-iii "中心对称数 III")
-
-<p>A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).</p>
-
-<p>Write a function to count the total strobogrammatic numbers that exist in the range of low &lt;= num &lt;= high.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-<b>Input:</b> low = &quot;50&quot;, high = &quot;100&quot;
-<b>Output:</b> 3 
-<strong>Explanation: </strong>69, 88, and 96 are three strobogrammatic numbers.</pre>
-
-<p><strong>Note:</strong><br />
-Because the range might be a large number, the <em>low</em> and <em>high</em> numbers are represented as string.</p>
-
-### Related Topics
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Strobogrammatic Number](../strobogrammatic-number) (Easy)
-  1. [Strobogrammatic Number II](../strobogrammatic-number-ii) (Medium)
diff --git a/problems/strobogrammatic-number-iii/strobogrammatic_number_iii.go b/problems/strobogrammatic-number-iii/strobogrammatic_number_iii.go
deleted file mode 100644
index 9397b2fa9..000000000
--- a/problems/strobogrammatic-number-iii/strobogrammatic_number_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem248
diff --git a/problems/strobogrammatic-number-iii/strobogrammatic_number_iii_test.go b/problems/strobogrammatic-number-iii/strobogrammatic_number_iii_test.go
deleted file mode 100644
index 9397b2fa9..000000000
--- a/problems/strobogrammatic-number-iii/strobogrammatic_number_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem248
diff --git a/problems/strobogrammatic-number/README.md b/problems/strobogrammatic-number/README.md
deleted file mode 100644
index 781c90165..000000000
--- a/problems/strobogrammatic-number/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-word-distance-iii "Shortest Word Distance III")
-　　　　　　　　　　　　　　　　
-[Next >](../strobogrammatic-number-ii "Strobogrammatic Number II")
-
-## [246. Strobogrammatic Number (Easy)](https://leetcode.com/problems/strobogrammatic-number "中心对称数")
-
-<p>A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).</p>
-
-<p>Write a function to determine if a number is strobogrammatic. The number is represented as a string.</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<b>Input:</b>  &quot;69&quot;
-<b>Output:</b> true
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<b>Input:</b>  &quot;88&quot;
-<b>Output:</b> true</pre>
-
-<p><b>Example 3:</b></p>
-
-<pre>
-<b>Input:</b>  &quot;962&quot;
-<b>Output:</b> false</pre>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Strobogrammatic Number II](../strobogrammatic-number-ii) (Medium)
-  1. [Strobogrammatic Number III](../strobogrammatic-number-iii) (Hard)
-  1. [Confusing Number](../confusing-number) (Easy)
diff --git a/problems/strobogrammatic-number/strobogrammatic_number.go b/problems/strobogrammatic-number/strobogrammatic_number.go
deleted file mode 100644
index 17911bb91..000000000
--- a/problems/strobogrammatic-number/strobogrammatic_number.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem246
diff --git a/problems/strobogrammatic-number/strobogrammatic_number_test.go b/problems/strobogrammatic-number/strobogrammatic_number_test.go
deleted file mode 100644
index 17911bb91..000000000
--- a/problems/strobogrammatic-number/strobogrammatic_number_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem246
diff --git a/problems/strong-friendship/README.md b/problems/strong-friendship/README.md
deleted file mode 100644
index 793c73063..000000000
--- a/problems/strong-friendship/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-duplicate-folders-in-system "Delete Duplicate Folders in System")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-of-minimum-values-in-all-subarrays "Maximum of Minimum Values in All Subarrays")
-
-## [1949. Strong Friendship (Medium)](https://leetcode.com/problems/strong-friendship "坚定的友谊")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/strong-friendship/mysql_schemas.sql b/problems/strong-friendship/mysql_schemas.sql
deleted file mode 100644
index e542a265f..000000000
--- a/problems/strong-friendship/mysql_schemas.sql
+++ /dev/null
@@ -1,14 +0,0 @@
-Create table If Not Exists Friendship (user1_id int, user2_id int);
-Truncate table Friendship;
-insert into Friendship (user1_id, user2_id) values ('1', '2');
-insert into Friendship (user1_id, user2_id) values ('1', '3');
-insert into Friendship (user1_id, user2_id) values ('2', '3');
-insert into Friendship (user1_id, user2_id) values ('1', '4');
-insert into Friendship (user1_id, user2_id) values ('2', '4');
-insert into Friendship (user1_id, user2_id) values ('1', '5');
-insert into Friendship (user1_id, user2_id) values ('2', '5');
-insert into Friendship (user1_id, user2_id) values ('1', '7');
-insert into Friendship (user1_id, user2_id) values ('3', '7');
-insert into Friendship (user1_id, user2_id) values ('1', '6');
-insert into Friendship (user1_id, user2_id) values ('3', '6');
-insert into Friendship (user1_id, user2_id) values ('2', '6');
diff --git a/problems/strong-password-checker/README.md b/problems/strong-password-checker/README.md
deleted file mode 100644
index e52efecb5..000000000
--- a/problems/strong-password-checker/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../battleships-in-a-board "Battleships in a Board")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-xor-of-two-numbers-in-an-array "Maximum XOR of Two Numbers in an Array")
-
-## [420. Strong Password Checker (Hard)](https://leetcode.com/problems/strong-password-checker "强密码检验器")
-
-<p>A password is considered strong if the below conditions are all met:</p>
-
-<ul>
-	<li>It has at least <code>6</code> characters and at most <code>20</code> characters.</li>
-	<li>It contains at least <strong>one lowercase</strong> letter, at least <strong>one uppercase</strong> letter, and at least <strong>one digit</strong>.</li>
-	<li>It does&nbsp;not contain three repeating characters in a row (i.e.,&nbsp;<code>&quot;...aaa...&quot;</code> is weak, but <code>&quot;...aa...a...&quot;</code> is strong, assuming other conditions are met).</li>
-</ul>
-
-<p>Given a string <code>password</code>, return <em>the minimum number of steps required to make <code>password</code> strong. if <code>password</code> is already strong, return <code>0</code>.</em></p>
-
-<p>In one step, you can:</p>
-
-<ul>
-	<li>Insert one character to <code>password</code>,</li>
-	<li>Delete one character from <code>password</code>, or</li>
-	<li>Replace&nbsp;one character of <code>password</code> with another character.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> password = "a"
-<strong>Output:</strong> 5
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> password = "aA1"
-<strong>Output:</strong> 3
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> password = "1337C0d3"
-<strong>Output:</strong> 0
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= password.length &lt;= 50</code></li>
-	<li><code>password</code> consists of letters, digits, dot&nbsp;<code>&#39;.&#39;</code> or exclamation mark <code>&#39;!&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
diff --git a/problems/strong-password-checker/strong_password_checker.go b/problems/strong-password-checker/strong_password_checker.go
deleted file mode 100644
index 6564db863..000000000
--- a/problems/strong-password-checker/strong_password_checker.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem420
diff --git a/problems/strong-password-checker/strong_password_checker_test.go b/problems/strong-password-checker/strong_password_checker_test.go
deleted file mode 100644
index 6564db863..000000000
--- a/problems/strong-password-checker/strong_password_checker_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem420
diff --git a/problems/student-attendance-record-i/README.md b/problems/student-attendance-record-i/README.md
deleted file mode 100644
index edbe92853..000000000
--- a/problems/student-attendance-record-i/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../game-play-analysis-iv "Game Play Analysis IV")
-　　　　　　　　　　　　　　　　
-[Next >](../student-attendance-record-ii "Student Attendance Record II")
-
-## [551. Student Attendance Record I (Easy)](https://leetcode.com/problems/student-attendance-record-i "学生出勤记录 I")
-
-<p>You are given a string <code>s</code> representing an attendance record for a student where each character signifies whether the student was absent, late, or present on that day. The record only contains the following three characters:</p>
-
-<ul>
-	<li><code>&#39;A&#39;</code>: Absent.</li>
-	<li><code>&#39;L&#39;</code>: Late.</li>
-	<li><code>&#39;P&#39;</code>: Present.</li>
-</ul>
-
-<p>The student is eligible for an attendance award if they meet <strong>both</strong> of the following criteria:</p>
-
-<ul>
-	<li>The student was absent (<code>&#39;A&#39;</code>) for <strong>strictly</strong> fewer than 2 days <strong>total</strong>.</li>
-	<li>The student was <strong>never</strong> late (<code>&#39;L&#39;</code>) for 3 or more <strong>consecutive</strong> days.</li>
-</ul>
-
-<p>Return <code>true</code><em> if the student is eligible for an attendance award, or </em><code>false</code><em> otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;PPALLP&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The student has fewer than 2 absences and was never late 3 or more consecutive days.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;PPALLL&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The student was late 3 consecutive days in the last 3 days, so is not eligible for the award.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s[i]</code> is either <code>&#39;A&#39;</code>, <code>&#39;L&#39;</code>, or <code>&#39;P&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Student Attendance Record II](../student-attendance-record-ii) (Hard)
diff --git a/problems/student-attendance-record-i/student_attendance_record_i.go b/problems/student-attendance-record-i/student_attendance_record_i.go
deleted file mode 100644
index a8d319751..000000000
--- a/problems/student-attendance-record-i/student_attendance_record_i.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem551
-
-import "strings"
-
-func checkRecord(s string) bool {
-	return !strings.Contains(s, "LLL") && strings.Count(s, "A") <= 1
-}
diff --git a/problems/student-attendance-record-i/student_attendance_record_i_test.go b/problems/student-attendance-record-i/student_attendance_record_i_test.go
deleted file mode 100644
index 76b4f54f4..000000000
--- a/problems/student-attendance-record-i/student_attendance_record_i_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem551
-
-import "testing"
-
-type testType struct {
-	in   string
-	want bool
-}
-
-func TestCheckRecord(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "PPALLP",
-			want: true,
-		},
-		{
-			in:   "PPALLL",
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := checkRecord(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/student-attendance-record-ii/README.md b/problems/student-attendance-record-ii/README.md
deleted file mode 100644
index 6931ce270..000000000
--- a/problems/student-attendance-record-ii/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../student-attendance-record-i "Student Attendance Record I")
-　　　　　　　　　　　　　　　　
-[Next >](../optimal-division "Optimal Division")
-
-## [552. Student Attendance Record II (Hard)](https://leetcode.com/problems/student-attendance-record-ii "学生出勤记录 II")
-
-<p>An attendance record for a student can be represented as a string where each character signifies whether the student was absent, late, or present on that day. The record only contains the following three characters:</p>
-
-<ul>
-	<li><code>&#39;A&#39;</code>: Absent.</li>
-	<li><code>&#39;L&#39;</code>: Late.</li>
-	<li><code>&#39;P&#39;</code>: Present.</li>
-</ul>
-
-<p>Any student is eligible for an attendance award if they meet <strong>both</strong> of the following criteria:</p>
-
-<ul>
-	<li>The student was absent (<code>&#39;A&#39;</code>) for <strong>strictly</strong> fewer than 2 days <strong>total</strong>.</li>
-	<li>The student was <strong>never</strong> late (<code>&#39;L&#39;</code>) for 3 or more <strong>consecutive</strong> days.</li>
-</ul>
-
-<p>Given an integer <code>n</code>, return <em>the <strong>number</strong> of possible attendance records of length</em> <code>n</code><em> that make a student eligible for an attendance award. The answer may be very large, so return it <strong>modulo</strong> </em><code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> There are 8 records with length 2 that are eligible for an award:
-&quot;PP&quot;, &quot;AP&quot;, &quot;PA&quot;, &quot;LP&quot;, &quot;PL&quot;, &quot;AL&quot;, &quot;LA&quot;, &quot;LL&quot;
-Only &quot;AA&quot; is not eligible because there are 2 absences (there need to be fewer than 2).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10101
-<strong>Output:</strong> 183236316
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Student Attendance Record I](../student-attendance-record-i) (Easy)
diff --git a/problems/student-attendance-record-ii/student_attendance_record_ii.go b/problems/student-attendance-record-ii/student_attendance_record_ii.go
deleted file mode 100644
index d11f8ac56..000000000
--- a/problems/student-attendance-record-ii/student_attendance_record_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem552
diff --git a/problems/student-attendance-record-ii/student_attendance_record_ii_test.go b/problems/student-attendance-record-ii/student_attendance_record_ii_test.go
deleted file mode 100644
index d11f8ac56..000000000
--- a/problems/student-attendance-record-ii/student_attendance_record_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem552
diff --git a/problems/students-and-examinations/README.md b/problems/students-and-examinations/README.md
deleted file mode 100644
index e9b327fe4..000000000
--- a/problems/students-and-examinations/README.md
+++ /dev/null
@@ -1,114 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../traffic-light-controlled-intersection "Traffic Light Controlled Intersection")
-　　　　　　　　　　　　　　　　
-[Next >](../subtract-the-product-and-sum-of-digits-of-an-integer "Subtract the Product and Sum of Digits of an Integer")
-
-## [1280. Students and Examinations (Easy)](https://leetcode.com/problems/students-and-examinations "学生们参加各科测试的次数")
-
-<p>Table: <code>Students</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| student_id    | int     |
-| student_name  | varchar |
-+---------------+---------+
-student_id is the primary key for this table.
-Each row of this table contains the ID and the name of one student in the school.
-</pre>
- 
-<p>Table: <code>Subjects</code></p>
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| subject_name | varchar |
-+--------------+---------+
-subject_name is the primary key for this table.
-Each row of this table contains a name of one subject in the school.
-</pre>
- 
-<p>Table: <code>Examinations</code></p>
-<pre>
-+--------------+---------+
-| Column Name  | Type    |
-+--------------+---------+
-| student_id   | int     |
-| subject_name | varchar |
-+--------------+---------+
-There is no primary key for this table. It may contain duplicates.
-Each student from Students table takes every course from Subjects table.
-Each row of this table indicates that a student with ID student_id attended the exam of subject_name.
-</pre>
- 
-Write an SQL query to find the number of times each student attended each exam.
-
-Order the result table by student_id and subject_name.
-
-The query result format is in the following example:
-<pre>
-Students table:
-+------------+--------------+
-| student_id | student_name |
-+------------+--------------+
-| 1          | Alice        |
-| 2          | Bob          |
-| 13         | John         |
-| 6          | Alex         |
-+------------+--------------+
-Subjects table:
-+--------------+
-| subject_name |
-+--------------+
-| Math         |
-| Physics      |
-| Programming  |
-+--------------+
-Examinations table:
-+------------+--------------+
-| student_id | subject_name |
-+------------+--------------+
-| 1          | Math         |
-| 1          | Physics      |
-| 1          | Programming  |
-| 2          | Programming  |
-| 1          | Physics      |
-| 1          | Math         |
-| 13         | Math         |
-| 13         | Programming  |
-| 13         | Physics      |
-| 2          | Math         |
-| 1          | Math         |
-+------------+--------------+
-Result table:
-+------------+--------------+--------------+----------------+
-| student_id | student_name | subject_name | attended_exams |
-+------------+--------------+--------------+----------------+
-| 1          | Alice        | Math         | 3              |
-| 1          | Alice        | Physics      | 2              |
-| 1          | Alice        | Programming  | 1              |
-| 2          | Bob          | Math         | 1              |
-| 2          | Bob          | Physics      | 0              |
-| 2          | Bob          | Programming  | 1              |
-| 6          | Alex         | Math         | 0              |
-| 6          | Alex         | Physics      | 0              |
-| 6          | Alex         | Programming  | 0              |
-| 13         | John         | Math         | 1              |
-| 13         | John         | Physics      | 1              |
-| 13         | John         | Programming  | 1              |
-+------------+--------------+--------------+----------------+
-The result table should contain all students and all subjects.
-Alice attended Math exam 3 times, Physics exam 2 times and Programming exam 1 time.
-Bob attended Math exam 1 time, Programming exam 1 time and didn't attend the Physics exam.
-Alex didn't attend any exam.
-John attended Math exam 1 time, Physics exam 1 time and Programming exam 1 time.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/students-and-examinations/mysql_schemas.sql b/problems/students-and-examinations/mysql_schemas.sql
deleted file mode 100644
index 4664a44c1..000000000
--- a/problems/students-and-examinations/mysql_schemas.sql
+++ /dev/null
@@ -1,24 +0,0 @@
-Create table If Not Exists Students (student_id int, student_name varchar(20));
-Create table If Not Exists Subjects (subject_name varchar(20));
-Create table If Not Exists Examinations (student_id int, subject_name varchar(20));
-Truncate table Students;
-insert into Students (student_id, student_name) values ('1', 'Alice');
-insert into Students (student_id, student_name) values ('2', 'Bob');
-insert into Students (student_id, student_name) values ('13', 'John');
-insert into Students (student_id, student_name) values ('6', 'Alex');
-Truncate table Subjects;
-insert into Subjects (subject_name) values ('Math');
-insert into Subjects (subject_name) values ('Physics');
-insert into Subjects (subject_name) values ('Programming');
-Truncate table Examinations;
-insert into Examinations (student_id, subject_name) values ('1', 'Math');
-insert into Examinations (student_id, subject_name) values ('1', 'Physics');
-insert into Examinations (student_id, subject_name) values ('1', 'Programming');
-insert into Examinations (student_id, subject_name) values ('2', 'Programming');
-insert into Examinations (student_id, subject_name) values ('1', 'Physics');
-insert into Examinations (student_id, subject_name) values ('1', 'Math');
-insert into Examinations (student_id, subject_name) values ('13', 'Math');
-insert into Examinations (student_id, subject_name) values ('13', 'Programming');
-insert into Examinations (student_id, subject_name) values ('13', 'Physics');
-insert into Examinations (student_id, subject_name) values ('2', 'Math');
-insert into Examinations (student_id, subject_name) values ('1', 'Math');
diff --git a/problems/students-report-by-geography/README.md b/problems/students-report-by-geography/README.md
deleted file mode 100644
index 1d661e8f6..000000000
--- a/problems/students-report-by-geography/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../merge-two-binary-trees "Merge Two Binary Trees")
-　　　　　　　　　　　　　　　　
-[Next >](../biggest-single-number "Biggest Single Number")
-
-## [618. Students Report By Geography (Hard)](https://leetcode.com/problems/students-report-by-geography "学生地理信息报告")
-
-A U.S graduate school has students from Asia, Europe and America. The students&#39; location information are stored in table <code>student</code> as below.
-<p>&nbsp;</p>
-
-<pre>
-| name   | continent |
-|--------|-----------|
-| Jack   | America   |
-| Pascal | Europe    |
-| Xi     | Asia      |
-| Jane   | America   |
-</pre>
-
-<p>&nbsp;</p>
-<a href="https://en.wikipedia.org/wiki/Pivot_table"> Pivot</a> the continent column in this table so that each name is sorted alphabetically and displayed underneath its corresponding continent. The output headers should be America, Asia and Europe respectively. It is guaranteed that the student number from America is no less than either Asia or Europe.
-
-<p>&nbsp;</p>
-For the sample input, the output is:
-
-<p>&nbsp;</p>
-
-<pre>
-| America | Asia | Europe |
-|---------|------|--------|
-| Jack    | Xi   | Pascal |
-| Jane    |      |        |
-</pre>
-
-<p>&nbsp;</p>
-<b>Follow-up:</b> If it is unknown which continent has the most students, can you write a query to generate the student report?
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/students-report-by-geography/mysql_schemas.sql b/problems/students-report-by-geography/mysql_schemas.sql
deleted file mode 100644
index 271a37487..000000000
--- a/problems/students-report-by-geography/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Student (name varchar(50), continent varchar(7));
-Truncate table Student;
-insert into Student (name, continent) values ('Jane', 'America');
-insert into Student (name, continent) values ('Pascal', 'Europe');
-insert into Student (name, continent) values ('Xi', 'Asia');
-insert into Student (name, continent) values ('Jack', 'America');
diff --git a/problems/students-report-by-geography/students_report_by_geography.sql b/problems/students-report-by-geography/students_report_by_geography.sql
deleted file mode 100644
index 1c99109b1..000000000
--- a/problems/students-report-by-geography/students_report_by_geography.sql
+++ /dev/null
@@ -1,29 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT
-  America, Asia, Europe
-FROM
-  (SELECT @as:=0, @am:=0, @eu:=0) t,
-  (SELECT
-     @as:=@as + 1 AS asid, name AS Asia
-   FROM
-     student
-   WHERE
-     continent = 'Asia'
-   ORDER BY Asia) AS t1
-  RIGHT JOIN
-  (SELECT
-     @am:=@am + 1 AS amid, name AS America
-   FROM
-     student
-   WHERE
-     continent = 'America'
-   ORDER BY America) AS t2 ON asid = amid
-  LEFT JOIN
-  (SELECT
-     @eu:=@eu + 1 AS euid, name AS Europe
-   FROM
-     student
-   WHERE
-     continent = 'Europe'
-   ORDER BY Europe) AS t3 ON amid = euid;
diff --git a/problems/students-with-invalid-departments/README.md b/problems/students-with-invalid-departments/README.md
deleted file mode 100644
index ea308e0fa..000000000
--- a/problems/students-with-invalid-departments/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-students-taking-exam "Maximum Students Taking Exam")
-　　　　　　　　　　　　　　　　
-[Next >](../count-negative-numbers-in-a-sorted-matrix "Count Negative Numbers in a Sorted Matrix")
-
-## [1350. Students With Invalid Departments (Easy)](https://leetcode.com/problems/students-with-invalid-departments "院系无效的学生")
-
-<p>Table: <code>Departments</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| name          | varchar |
-+---------------+---------+
-id is the primary key of this table.
-The table has information about the id of each department of a university.
-</pre>
- 
-<p>Table: <code>Students</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| name          | varchar |
-| department_id | int     |
-+---------------+---------+
-id is the primary key of this table.
-The table has information about the id of each student at a university and the id of the department he/she studies at.
-</pre>
- 
-Write an SQL query to find the id and the name of all students who are enrolled in departments that no longer exists.
-
-Return the result table in any order.
-
-The query result format is in the following example:
-<pre>
-Departments table:
-+------+--------------------------+
-| id   | name                     |
-+------+--------------------------+
-| 1    | Electrical Engineering   |
-| 7    | Computer Engineering     |
-| 13   | Bussiness Administration |
-+------+--------------------------+
-
-Students table:
-+------+----------+---------------+
-| id   | name     | department_id |
-+------+----------+---------------+
-| 23   | Alice    | 1             |
-| 1    | Bob      | 7             |
-| 5    | Jennifer | 13            |
-| 2    | John     | 14            |
-| 4    | Jasmine  | 77            |
-| 3    | Steve    | 74            |
-| 6    | Luis     | 1             |
-| 8    | Jonathan | 7             |
-| 7    | Daiana   | 33            |
-| 11   | Madelynn | 1             |
-+------+----------+---------------+
-
-Result table:
-+------+----------+
-| id   | name     |
-+------+----------+
-| 2    | John     |
-| 7    | Daiana   |
-| 4    | Jasmine  |
-| 3    | Steve    |
-+------+----------+
-
-John, Daiana, Steve and Jasmine are enrolled in departments 14, 33, 74 and 77 respectively. department 14, 33, 74 and 77 doesn't exist in the Departments table.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/students-with-invalid-departments/mysql_schemas.sql b/problems/students-with-invalid-departments/mysql_schemas.sql
deleted file mode 100644
index 3f3e4af12..000000000
--- a/problems/students-with-invalid-departments/mysql_schemas.sql
+++ /dev/null
@@ -1,17 +0,0 @@
-Create table If Not Exists Departments (id int, name varchar(30));
-Create table If Not Exists Students (id int, name varchar(30), department_id int);
-Truncate table Departments;
-insert into Departments (id, name) values ('1', 'Electrical Engineering');
-insert into Departments (id, name) values ('7', 'Computer Engineering');
-insert into Departments (id, name) values ('13', 'Bussiness Administration');
-Truncate table Students;
-insert into Students (id, name, department_id) values ('23', 'Alice', '1');
-insert into Students (id, name, department_id) values ('1', 'Bob', '7');
-insert into Students (id, name, department_id) values ('5', 'Jennifer', '13');
-insert into Students (id, name, department_id) values ('2', 'John', '14');
-insert into Students (id, name, department_id) values ('4', 'Jasmine', '77');
-insert into Students (id, name, department_id) values ('3', 'Steve', '74');
-insert into Students (id, name, department_id) values ('6', 'Luis', '1');
-insert into Students (id, name, department_id) values ('8', 'Jonathan', '7');
-insert into Students (id, name, department_id) values ('7', 'Daiana', '33');
-insert into Students (id, name, department_id) values ('11', 'Madelynn', '1');
diff --git a/problems/subarray-product-less-than-k/README.md b/problems/subarray-product-less-than-k/README.md
deleted file mode 100644
index 3597aca60..000000000
--- a/problems/subarray-product-less-than-k/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-ascii-delete-sum-for-two-strings "Minimum ASCII Delete Sum for Two Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../best-time-to-buy-and-sell-stock-with-transaction-fee "Best Time to Buy and Sell Stock with Transaction Fee")
-
-## [713. Subarray Product Less Than K (Medium)](https://leetcode.com/problems/subarray-product-less-than-k "乘积小于K的子数组")
-
-<p>Given an array of integers <code>nums</code> and an integer <code>k</code>, return <em>the number of contiguous subarrays where the product of all the elements in the subarray is strictly less than </em><code>k</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [10,5,2,6], k = 100
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> The 8 subarrays that have product less than 100 are:
-[10], [5], [2], [6], [10, 5], [5, 2], [2, 6], [5, 2, 6]
-Note that [10, 5, 2] is not included as the product of 100 is not strictly less than k.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3], k = 0
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 1000</code></li>
-	<li><code>0 &lt;= k &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Maximum Product Subarray](../maximum-product-subarray) (Medium)
-  1. [Maximum Size Subarray Sum Equals k](../maximum-size-subarray-sum-equals-k) (Medium)
-  1. [Subarray Sum Equals K](../subarray-sum-equals-k) (Medium)
-  1. [Two Sum Less Than K](../two-sum-less-than-k) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-For each j, let opt(j) be the smallest i so that nums[i] * nums[i+1] * ... * nums[j] is less than k.  opt is an increasing function.
-</details>
diff --git a/problems/subarray-product-less-than-k/subarray_product_less_than_k.go b/problems/subarray-product-less-than-k/subarray_product_less_than_k.go
deleted file mode 100644
index f7b836b8a..000000000
--- a/problems/subarray-product-less-than-k/subarray_product_less_than_k.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem713
diff --git a/problems/subarray-product-less-than-k/subarray_product_less_than_k_test.go b/problems/subarray-product-less-than-k/subarray_product_less_than_k_test.go
deleted file mode 100644
index f7b836b8a..000000000
--- a/problems/subarray-product-less-than-k/subarray_product_less_than_k_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem713
diff --git a/problems/subarray-sum-equals-k/README.md b/problems/subarray-sum-equals-k/README.md
deleted file mode 100644
index c2756c8bc..000000000
--- a/problems/subarray-sum-equals-k/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-depth-of-n-ary-tree "Maximum Depth of N-ary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../array-partition-i "Array Partition I")
-
-## [560. Subarray Sum Equals K (Medium)](https://leetcode.com/problems/subarray-sum-equals-k "和为 K 的子数组")
-
-<p>Given an array of integers <code>nums</code> and an integer <code>k</code>, return <em>the total number of continuous subarrays whose sum equals to <code>k</code></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1,1], k = 2
-<strong>Output:</strong> 2
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,3], k = 3
-<strong>Output:</strong> 2
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>-1000 &lt;= nums[i] &lt;= 1000</code></li>
-	<li><code>-10<sup>7</sup> &lt;= k &lt;= 10<sup>7</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Two Sum](../two-sum) (Easy)
-  1. [Continuous Subarray Sum](../continuous-subarray-sum) (Medium)
-  1. [Subarray Product Less Than K](../subarray-product-less-than-k) (Medium)
-  1. [Find Pivot Index](../find-pivot-index) (Easy)
-  1. [Subarray Sums Divisible by K](../subarray-sums-divisible-by-k) (Medium)
-  1. [Minimum Operations to Reduce X to Zero](../minimum-operations-to-reduce-x-to-zero) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Will Brute force work here? Try to optimize it.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we optimize it by using some extra space?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What about storing sum frequencies in a hash table? Will it be useful?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-sum(i,j)=sum(0,j)-sum(0,i), where sum(i,j) represents the sum of all the elements from index i to j-1.
-
-Can we use this property to optimize it.
-</details>
diff --git a/problems/subarray-sum-equals-k/subarray_sum_equals_k.go b/problems/subarray-sum-equals-k/subarray_sum_equals_k.go
deleted file mode 100644
index 214094230..000000000
--- a/problems/subarray-sum-equals-k/subarray_sum_equals_k.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem560
diff --git a/problems/subarray-sum-equals-k/subarray_sum_equals_k_test.go b/problems/subarray-sum-equals-k/subarray_sum_equals_k_test.go
deleted file mode 100644
index 214094230..000000000
--- a/problems/subarray-sum-equals-k/subarray_sum_equals_k_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem560
diff --git a/problems/subarray-sums-divisible-by-k/README.md b/problems/subarray-sums-divisible-by-k/README.md
deleted file mode 100644
index 15e7339d0..000000000
--- a/problems/subarray-sums-divisible-by-k/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../k-closest-points-to-origin "K Closest Points to Origin")
-　　　　　　　　　　　　　　　　
-[Next >](../odd-even-jump "Odd Even Jump")
-
-## [974. Subarray Sums Divisible by K (Medium)](https://leetcode.com/problems/subarray-sums-divisible-by-k "和可被 K 整除的子数组")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the number of non-empty <strong>subarrays</strong> that have a sum divisible by </em><code>k</code>.</p>
-
-<p>A <strong>subarray</strong> is a <strong>contiguous</strong> part of an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,5,0,-2,-3,1], k = 5
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> There are 7 subarrays with a sum divisible by k = 5:
-[4, 5, 0, -2, -3, 1], [5], [5, 0], [5, 0, -2, -3], [0], [0, -2, -3], [-2, -3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5], k = 9
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>2 &lt;= k &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Subarray Sum Equals K](../subarray-sum-equals-k) (Medium)
diff --git a/problems/subarray-sums-divisible-by-k/subarray_sums_divisible_by_k.go b/problems/subarray-sums-divisible-by-k/subarray_sums_divisible_by_k.go
deleted file mode 100644
index 876bd9bd4..000000000
--- a/problems/subarray-sums-divisible-by-k/subarray_sums_divisible_by_k.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem974
diff --git a/problems/subarrays-with-k-different-integers/README.md b/problems/subarrays-with-k-different-integers/README.md
deleted file mode 100644
index b3ee2f146..000000000
--- a/problems/subarrays-with-k-different-integers/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../broken-calculator "Broken Calculator")
-　　　　　　　　　　　　　　　　
-[Next >](../cousins-in-binary-tree "Cousins in Binary Tree")
-
-## [992. Subarrays with K Different Integers (Hard)](https://leetcode.com/problems/subarrays-with-k-different-integers "K 个不同整数的子数组")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the number of <strong>good subarrays</strong> of </em><code>nums</code>.</p>
-
-<p>A <strong>good array</strong> is an array where the number of different integers in that array is exactly <code>k</code>.</p>
-
-<ul>
-	<li>For example, <code>[1,2,3,1,2]</code> has <code>3</code> different integers: <code>1</code>, <code>2</code>, and <code>3</code>.</li>
-</ul>
-
-<p>A <strong>subarray</strong> is a <strong>contiguous</strong> part of an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1,2,3], k = 2
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> Subarrays formed with exactly 2 different integers: [1,2], [2,1], [1,2], [2,3], [1,2,1], [2,1,2], [1,2,1,2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,1,3,4], k = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Subarrays formed with exactly 3 different integers: [1,2,1,3], [2,1,3], [1,3,4].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= nums[i], k &lt;= nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Longest Substring Without Repeating Characters](../longest-substring-without-repeating-characters) (Medium)
-  1. [Longest Substring with At Most Two Distinct Characters](../longest-substring-with-at-most-two-distinct-characters) (Medium)
-  1. [Longest Substring with At Most K Distinct Characters](../longest-substring-with-at-most-k-distinct-characters) (Medium)
diff --git a/problems/subarrays-with-k-different-integers/subarrays_with_k_different_integers.go b/problems/subarrays-with-k-different-integers/subarrays_with_k_different_integers.go
deleted file mode 100644
index b69ae9876..000000000
--- a/problems/subarrays-with-k-different-integers/subarrays_with_k_different_integers.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem992
diff --git a/problems/subdomain-visit-count/README.md b/problems/subdomain-visit-count/README.md
deleted file mode 100644
index 700b534f3..000000000
--- a/problems/subdomain-visit-count/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../chalkboard-xor-game "Chalkboard XOR Game")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-triangle-area "Largest Triangle Area")
-
-## [811. Subdomain Visit Count (Medium)](https://leetcode.com/problems/subdomain-visit-count "子域名访问计数")
-
-<p>A website domain <code>&quot;discuss.leetcode.com&quot;</code> consists of various subdomains. At the top level, we have <code>&quot;com&quot;</code>, at the next level, we have <code>&quot;leetcode.com&quot;</code>&nbsp;and at the lowest level, <code>&quot;discuss.leetcode.com&quot;</code>. When we visit a domain like <code>&quot;discuss.leetcode.com&quot;</code>, we will also visit the parent domains <code>&quot;leetcode.com&quot;</code> and <code>&quot;com&quot;</code> implicitly.</p>
-
-<p>A <strong>count-paired domain</strong> is a domain that has one of the two formats <code>&quot;rep d1.d2.d3&quot;</code> or <code>&quot;rep d1.d2&quot;</code> where <code>rep</code> is the number of visits to the domain and <code>d1.d2.d3</code> is the domain itself.</p>
-
-<ul>
-	<li>For example, <code>&quot;9001 discuss.leetcode.com&quot;</code> is a <strong>count-paired domain</strong> that indicates that <code>discuss.leetcode.com</code> was visited <code>9001</code> times.</li>
-</ul>
-
-<p>Given an array of <strong>count-paired domains</strong> <code>cpdomains</code>, return <em>an array of the <strong>count-paired domains</strong> of each subdomain in the input</em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> cpdomains = [&quot;9001 discuss.leetcode.com&quot;]
-<strong>Output:</strong> [&quot;9001 leetcode.com&quot;,&quot;9001 discuss.leetcode.com&quot;,&quot;9001 com&quot;]
-<strong>Explanation:</strong> We only have one website domain: &quot;discuss.leetcode.com&quot;.
-As discussed above, the subdomain &quot;leetcode.com&quot; and &quot;com&quot; will also be visited. So they will all be visited 9001 times.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> cpdomains = [&quot;900 google.mail.com&quot;, &quot;50 yahoo.com&quot;, &quot;1 intel.mail.com&quot;, &quot;5 wiki.org&quot;]
-<strong>Output:</strong> [&quot;901 mail.com&quot;,&quot;50 yahoo.com&quot;,&quot;900 google.mail.com&quot;,&quot;5 wiki.org&quot;,&quot;5 org&quot;,&quot;1 intel.mail.com&quot;,&quot;951 com&quot;]
-<strong>Explanation:</strong> We will visit &quot;google.mail.com&quot; 900 times, &quot;yahoo.com&quot; 50 times, &quot;intel.mail.com&quot; once and &quot;wiki.org&quot; 5 times.
-For the subdomains, we will visit &quot;mail.com&quot; 900 + 1 = 901 times, &quot;com&quot; 900 + 50 + 1 = 951 times, and &quot;org&quot; 5 times.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= cpdomain.length &lt;= 100</code></li>
-	<li><code>1 &lt;= cpdomain[i].length &lt;= 100</code></li>
-	<li><code>cpdomain[i]</code> follows either the <code>&quot;rep<sub>i</sub> d1<sub>i</sub>.d2<sub>i</sub>.d3<sub>i</sub>&quot;</code> format or the <code>&quot;rep<sub>i</sub> d1<sub>i</sub>.d2<sub>i</sub>&quot;</code> format.</li>
-	<li><code>rep<sub>i</sub></code> is an integer in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>d1<sub>i</sub></code>, <code>d2<sub>i</sub></code>, and <code>d3<sub>i</sub></code> consist of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/subdomain-visit-count/subdomain_visit_count.go b/problems/subdomain-visit-count/subdomain_visit_count.go
deleted file mode 100644
index 5c89a4d55..000000000
--- a/problems/subdomain-visit-count/subdomain_visit_count.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem811
diff --git a/problems/subdomain-visit-count/subdomain_visit_count_test.go b/problems/subdomain-visit-count/subdomain_visit_count_test.go
deleted file mode 100644
index 5c89a4d55..000000000
--- a/problems/subdomain-visit-count/subdomain_visit_count_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem811
diff --git a/problems/subrectangle-queries/README.md b/problems/subrectangle-queries/README.md
deleted file mode 100644
index 2f116e489..000000000
--- a/problems/subrectangle-queries/README.md
+++ /dev/null
@@ -1,105 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../final-prices-with-a-special-discount-in-a-shop "Final Prices With a Special Discount in a Shop")
-　　　　　　　　　　　　　　　　
-[Next >](../find-two-non-overlapping-sub-arrays-each-with-target-sum "Find Two Non-overlapping Sub-arrays Each With Target Sum")
-
-## [1476. Subrectangle Queries (Medium)](https://leetcode.com/problems/subrectangle-queries "子矩形查询")
-
-<p>Implement the class <code>SubrectangleQueries</code>&nbsp;which receives a <code>rows x cols</code> rectangle as a matrix of integers in the constructor and supports two methods:</p>
-
-<p>1.<code>&nbsp;updateSubrectangle(int row1, int col1, int row2, int col2, int newValue)</code></p>
-
-<ul>
-	<li>Updates all values with <code>newValue</code> in the subrectangle whose upper left coordinate is <code>(row1,col1)</code> and bottom right coordinate is <code>(row2,col2)</code>.</li>
-</ul>
-
-<p>2.<code>&nbsp;getValue(int row, int col)</code></p>
-
-<ul>
-	<li>Returns the current value of the coordinate <code>(row,col)</code> from&nbsp;the rectangle.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;SubrectangleQueries&quot;,&quot;getValue&quot;,&quot;updateSubrectangle&quot;,&quot;getValue&quot;,&quot;getValue&quot;,&quot;updateSubrectangle&quot;,&quot;getValue&quot;,&quot;getValue&quot;]
-[[[[1,2,1],[4,3,4],[3,2,1],[1,1,1]]],[0,2],[0,0,3,2,5],[0,2],[3,1],[3,0,3,2,10],[3,1],[0,2]]
-<strong>Output</strong>
-[null,1,null,5,5,null,10,5]
-<strong>Explanation</strong>
-SubrectangleQueries subrectangleQueries = new SubrectangleQueries([[1,2,1],[4,3,4],[3,2,1],[1,1,1]]);  
-// The initial rectangle (4x3) looks like:
-// 1 2 1
-// 4 3 4
-// 3 2 1
-// 1 1 1
-subrectangleQueries.getValue(0, 2); // return 1
-subrectangleQueries.updateSubrectangle(0, 0, 3, 2, 5);
-// After this update the rectangle looks like:
-// 5 5 5
-// 5 5 5
-// 5 5 5
-// 5 5 5 
-subrectangleQueries.getValue(0, 2); // return 5
-subrectangleQueries.getValue(3, 1); // return 5
-subrectangleQueries.updateSubrectangle(3, 0, 3, 2, 10);
-// After this update the rectangle looks like:
-// 5   5   5
-// 5   5   5
-// 5   5   5
-// 10  10  10 
-subrectangleQueries.getValue(3, 1); // return 10
-subrectangleQueries.getValue(0, 2); // return 5
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;SubrectangleQueries&quot;,&quot;getValue&quot;,&quot;updateSubrectangle&quot;,&quot;getValue&quot;,&quot;getValue&quot;,&quot;updateSubrectangle&quot;,&quot;getValue&quot;]
-[[[[1,1,1],[2,2,2],[3,3,3]]],[0,0],[0,0,2,2,100],[0,0],[2,2],[1,1,2,2,20],[2,2]]
-<strong>Output</strong>
-[null,1,null,100,100,null,20]
-<strong>Explanation</strong>
-SubrectangleQueries subrectangleQueries = new SubrectangleQueries([[1,1,1],[2,2,2],[3,3,3]]);
-subrectangleQueries.getValue(0, 0); // return 1
-subrectangleQueries.updateSubrectangle(0, 0, 2, 2, 100);
-subrectangleQueries.getValue(0, 0); // return 100
-subrectangleQueries.getValue(2, 2); // return 100
-subrectangleQueries.updateSubrectangle(1, 1, 2, 2, 20);
-subrectangleQueries.getValue(2, 2); // return 20
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>There will be at most <code><font face="monospace">500</font></code>&nbsp;operations considering both methods:&nbsp;<code>updateSubrectangle</code> and <code>getValue</code>.</li>
-	<li><code>1 &lt;= rows, cols &lt;= 100</code></li>
-	<li><code>rows ==&nbsp;rectangle.length</code></li>
-	<li><code>cols == rectangle[i].length</code></li>
-	<li><code>0 &lt;= row1 &lt;= row2 &lt; rows</code></li>
-	<li><code>0 &lt;= col1 &lt;= col2 &lt; cols</code></li>
-	<li><code>1 &lt;= newValue, rectangle[i][j] &lt;= 10^9</code></li>
-	<li><code>0 &lt;= row &lt; rows</code></li>
-	<li><code>0 &lt;= col &lt; cols</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Design](../../tag/design/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use brute force to update a rectangle and, response to the queries in O(1).
-</details>
diff --git a/problems/subsequence-of-size-k-with-the-largest-even-sum/README.md b/problems/subsequence-of-size-k-with-the-largest-even-sum/README.md
deleted file mode 100644
index b37446fc3..000000000
--- a/problems/subsequence-of-size-k-with-the-largest-even-sum/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-arrangement-of-pairs "Valid Arrangement of Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../find-subsequence-of-length-k-with-the-largest-sum "Find Subsequence of Length K With the Largest Sum")
-
-## [2098. Subsequence of Size K With the Largest Even Sum (Medium)](https://leetcode.com/problems/subsequence-of-size-k-with-the-largest-even-sum "")
-
-
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is the sum of two even numbers even or odd? How about two odd numbers? One odd number and one even number?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If there is an even number of odd numbers, the sum will be even and vice versa.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Create an integer array to store all the even numbers in nums and another array to store all the odd numbers in nums. Sort both arrays.
-</details>
diff --git a/problems/subsets-ii/README.md b/problems/subsets-ii/README.md
deleted file mode 100644
index 1f182abfd..000000000
--- a/problems/subsets-ii/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../gray-code "Gray Code")
-　　　　　　　　　　　　　　　　
-[Next >](../decode-ways "Decode Ways")
-
-## [90. Subsets II (Medium)](https://leetcode.com/problems/subsets-ii "子集 II")
-
-<p>Given an integer array <code>nums</code> that may contain duplicates, return <em>all possible subsets (the power set)</em>.</p>
-
-<p>The solution set <strong>must not</strong> contain duplicate subsets. Return the solution in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,2,2]
-<strong>Output:</strong> [[],[1],[1,2],[1,2,2],[2],[2,2]]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [0]
-<strong>Output:</strong> [[],[0]]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10</code></li>
-	<li><code>-10 &lt;= nums[i] &lt;= 10</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Subsets](../subsets) (Medium)
diff --git a/problems/subsets-ii/subsets_ii.go b/problems/subsets-ii/subsets_ii.go
deleted file mode 100644
index d2651e2f4..000000000
--- a/problems/subsets-ii/subsets_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem90
diff --git a/problems/subsets-ii/subsets_ii_test.go b/problems/subsets-ii/subsets_ii_test.go
deleted file mode 100644
index d2651e2f4..000000000
--- a/problems/subsets-ii/subsets_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem90
diff --git a/problems/subsets/README.md b/problems/subsets/README.md
deleted file mode 100644
index 28e5bcd05..000000000
--- a/problems/subsets/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../combinations "Combinations")
-　　　　　　　　　　　　　　　　
-[Next >](../word-search "Word Search")
-
-## [78. Subsets (Medium)](https://leetcode.com/problems/subsets "子集")
-
-<p>Given an integer array <code>nums</code> of <strong>unique</strong> elements, return <em>all possible subsets (the power set)</em>.</p>
-
-<p>The solution set <strong>must not</strong> contain duplicate subsets. Return the solution in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> [[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0]
-<strong>Output:</strong> [[],[0]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10</code></li>
-	<li><code>-10 &lt;= nums[i] &lt;= 10</code></li>
-	<li>All the numbers of&nbsp;<code>nums</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Subsets II](../subsets-ii) (Medium)
-  1. [Generalized Abbreviation](../generalized-abbreviation) (Medium)
-  1. [Letter Case Permutation](../letter-case-permutation) (Medium)
diff --git a/problems/subsets/subsets.go b/problems/subsets/subsets.go
deleted file mode 100644
index 7f10b2d97..000000000
--- a/problems/subsets/subsets.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem78
diff --git a/problems/subsets/subsets_test.go b/problems/subsets/subsets_test.go
deleted file mode 100644
index 7f10b2d97..000000000
--- a/problems/subsets/subsets_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem78
diff --git a/problems/substring-with-concatenation-of-all-words/README.md b/problems/substring-with-concatenation-of-all-words/README.md
deleted file mode 100644
index a24d4771a..000000000
--- a/problems/substring-with-concatenation-of-all-words/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../divide-two-integers "Divide Two Integers")
-　　　　　　　　　　　　　　　　
-[Next >](../next-permutation "Next Permutation")
-
-## [30. Substring with Concatenation of All Words (Hard)](https://leetcode.com/problems/substring-with-concatenation-of-all-words "串联所有单词的子串")
-
-<p>You are given a string <code>s</code> and an array of strings <code>words</code> of <strong>the same length</strong>. Return&nbsp;all starting indices of substring(s) in <code>s</code>&nbsp;that is a concatenation of each word in <code>words</code> <strong>exactly once</strong>, <strong>in any order</strong>,&nbsp;and <strong>without any intervening characters</strong>.</p>
-
-<p>You can return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;barfoothefoobarman&quot;, words = [&quot;foo&quot;,&quot;bar&quot;]
-<strong>Output:</strong> [0,9]
-<strong>Explanation:</strong> Substrings starting at index 0 and 9 are &quot;barfoo&quot; and &quot;foobar&quot; respectively.
-The output order does not matter, returning [9,0] is fine too.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;wordgoodgoodgoodbestword&quot;, words = [&quot;word&quot;,&quot;good&quot;,&quot;best&quot;,&quot;word&quot;]
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;barfoofoobarthefoobarman&quot;, words = [&quot;bar&quot;,&quot;foo&quot;,&quot;the&quot;]
-<strong>Output:</strong> [6,9,12]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of lower-case English letters.</li>
-	<li><code>1 &lt;= words.length &lt;= 5000</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 30</code></li>
-	<li><code>words[i]</code>&nbsp;consists of lower-case English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Similar Questions
-  1. [Minimum Window Substring](../minimum-window-substring) (Hard)
diff --git a/problems/substring-with-concatenation-of-all-words/substring_with_concatenation_of_all_words.go b/problems/substring-with-concatenation-of-all-words/substring_with_concatenation_of_all_words.go
deleted file mode 100644
index 459e51bfa..000000000
--- a/problems/substring-with-concatenation-of-all-words/substring_with_concatenation_of_all_words.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem30
diff --git a/problems/substring-with-concatenation-of-all-words/substring_with_concatenation_of_all_words_test.go b/problems/substring-with-concatenation-of-all-words/substring_with_concatenation_of_all_words_test.go
deleted file mode 100644
index 459e51bfa..000000000
--- a/problems/substring-with-concatenation-of-all-words/substring_with_concatenation_of_all_words_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem30
diff --git a/problems/substrings-of-size-three-with-distinct-characters/README.md b/problems/substrings-of-size-three-with-distinct-characters/README.md
deleted file mode 100644
index eedd2515f..000000000
--- a/problems/substrings-of-size-three-with-distinct-characters/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../group-employees-of-the-same-salary "Group Employees of the Same Salary")
-　　　　　　　　　　　　　　　　
-[Next >](../minimize-maximum-pair-sum-in-array "Minimize Maximum Pair Sum in Array")
-
-## [1876. Substrings of Size Three with Distinct Characters (Easy)](https://leetcode.com/problems/substrings-of-size-three-with-distinct-characters "长度为三且各字符不同的子字符串")
-
-<p>A string is <strong>good</strong> if there are no repeated characters.</p>
-
-<p>Given a string <code>s</code>​​​​​, return <em>the number of <strong>good substrings</strong> of length <strong>three </strong>in </em><code>s</code>​​​​​​.</p>
-
-<p>Note that if there are multiple occurrences of the same substring, every occurrence should be counted.</p>
-
-<p>A <strong>substring</strong> is a contiguous sequence of characters in a string.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;xyzzaz&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> There are 4 substrings of size 3: &quot;xyz&quot;, &quot;yzz&quot;, &quot;zza&quot;, and &quot;zaz&quot;. 
-The only good substring of length 3 is &quot;xyz&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aababcabc&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> There are 7 substrings of size 3: &quot;aab&quot;, &quot;aba&quot;, &quot;bab&quot;, &quot;abc&quot;, &quot;bca&quot;, &quot;cab&quot;, and &quot;abc&quot;.
-The good substrings are &quot;abc&quot;, &quot;bca&quot;, &quot;cab&quot;, and &quot;abc&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code>​​​​​​ consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try using a set to find out the number of distinct characters in a substring.
-</details>
diff --git a/problems/substrings-that-begin-and-end-with-the-same-letter/README.md b/problems/substrings-that-begin-and-end-with-the-same-letter/README.md
deleted file mode 100644
index 0bd2bd07a..000000000
--- a/problems/substrings-that-begin-and-end-with-the-same-letter/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-rich-customers "The Number of Rich Customers")
-　　　　　　　　　　　　　　　　
-[Next >](../drop-type-1-orders-for-customers-with-type-0-orders "Drop Type 1 Orders for Customers With Type 0 Orders")
-
-## [2083. Substrings That Begin and End With the Same Letter (Medium)](https://leetcode.com/problems/substrings-that-begin-and-end-with-the-same-letter "求以相同字母开头和结尾的子串总数")
-
-
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-In the string "abacad", the letter "a" appears 3 times. How many substrings begin with the first "a" and end with any "a"?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-There are 3 substrings ("a", "aba", and "abaca"). How many substrings begin with the second "a" and end with any "a"? How about the third?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-2 substrings begin with the second "a" ("a", and "aca") and 1 substring begins with the third "a" ("a").
-</details>
-
-<details>
-<summary>Hint 4</summary>
-There is a total of 3 + 2 + 1 = 6 substrings that begin and end with "a".
-</details>
-
-<details>
-<summary>Hint 5</summary>
-If a character appears i times in the string, there are i * (i + 1) / 2 substrings that begin and end with that character.
-</details>
diff --git a/problems/subtract-the-product-and-sum-of-digits-of-an-integer/README.md b/problems/subtract-the-product-and-sum-of-digits-of-an-integer/README.md
deleted file mode 100644
index bff43a94f..000000000
--- a/problems/subtract-the-product-and-sum-of-digits-of-an-integer/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../students-and-examinations "Students and Examinations")
-　　　　　　　　　　　　　　　　
-[Next >](../group-the-people-given-the-group-size-they-belong-to "Group the People Given the Group Size They Belong To")
-
-## [1281. Subtract the Product and Sum of Digits of an Integer (Easy)](https://leetcode.com/problems/subtract-the-product-and-sum-of-digits-of-an-integer "整数的各位积和之差")
-
-Given an integer number <code>n</code>, return the difference between the product of its digits and the sum of its digits.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 234
-<strong>Output:</strong> 15 
-<b>Explanation:</b> 
-Product of digits = 2 * 3 * 4 = 24 
-Sum of digits = 2 + 3 + 4 = 9 
-Result = 24 - 9 = 15
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4421
-<strong>Output:</strong> 21
-<b>Explanation: 
-</b>Product of digits = 4 * 4 * 2 * 1 = 32 
-Sum of digits = 4 + 4 + 2 + 1 = 11 
-Result = 32 - 11 = 21
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10^5</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to compute all digits of the number ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use modulus operator (%) to compute the last digit.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Generalise modulus operator idea to compute all digits.
-</details>
diff --git a/problems/subtree-of-another-tree/README.md b/problems/subtree-of-another-tree/README.md
deleted file mode 100644
index 654f1ec17..000000000
--- a/problems/subtree-of-another-tree/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-median-given-frequency-of-numbers "Find Median Given Frequency of Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../squirrel-simulation "Squirrel Simulation")
-
-## [572. Subtree of Another Tree (Easy)](https://leetcode.com/problems/subtree-of-another-tree "另一棵树的子树")
-
-<p>Given the roots of two binary trees <code>root</code> and <code>subRoot</code>, return <code>true</code> if there is a subtree of <code>root</code> with the same structure and node values of<code> subRoot</code> and <code>false</code> otherwise.</p>
-
-<p>A subtree of a binary tree <code>tree</code> is a tree that consists of a node in <code>tree</code> and all of this node&#39;s descendants. The tree <code>tree</code> could also be considered as a subtree of itself.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/28/subtree1-tree.jpg" style="width: 532px; height: 400px;" />
-<pre>
-<strong>Input:</strong> root = [3,4,5,1,2], subRoot = [4,1,2]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/28/subtree2-tree.jpg" style="width: 502px; height: 458px;" />
-<pre>
-<strong>Input:</strong> root = [3,4,5,1,2,null,null,null,null,0], subRoot = [4,1,2]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the <code>root</code> tree is in the range <code>[1, 2000]</code>.</li>
-	<li>The number of nodes in the <code>subRoot</code> tree is in the range <code>[1, 1000]</code>.</li>
-	<li><code>-10<sup>4</sup> &lt;= root.val &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= subRoot.val &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-  [[String Matching](../../tag/string-matching/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-
-### Similar Questions
-  1. [Count Univalue Subtrees](../count-univalue-subtrees) (Medium)
-  1. [Most Frequent Subtree Sum](../most-frequent-subtree-sum) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Which approach is better here- recursive or iterative?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If recursive approach is better, can you write recursive function with its parameters?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Two trees <b>s</b> and <b>t</b> are said to be identical if their root values are same and their left and right subtrees are identical. Can you write this in form of recursive formulae?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Recursive formulae can be: 
-isIdentical(s,t)= s.val==t.val AND isIdentical(s.left,t.left) AND isIdentical(s.right,t.right)
-</details>
diff --git a/problems/subtree-of-another-tree/subtree_of_another_tree.go b/problems/subtree-of-another-tree/subtree_of_another_tree.go
deleted file mode 100644
index f2db60217..000000000
--- a/problems/subtree-of-another-tree/subtree_of_another_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem572
diff --git a/problems/subtree-of-another-tree/subtree_of_another_tree_test.go b/problems/subtree-of-another-tree/subtree_of_another_tree_test.go
deleted file mode 100644
index f2db60217..000000000
--- a/problems/subtree-of-another-tree/subtree_of_another_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem572
diff --git a/problems/subtree-removal-game-with-fibonacci-tree/README.md b/problems/subtree-removal-game-with-fibonacci-tree/README.md
deleted file mode 100644
index 094bb4c14..000000000
--- a/problems/subtree-removal-game-with-fibonacci-tree/README.md
+++ /dev/null
@@ -1,30 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-number-of-seniors-and-juniors-to-join-the-company "The Number of Seniors and Juniors to Join the Company")
-　　　　　　　　　　　　　　　　
-[Next >](../count-number-of-pairs-with-absolute-difference-k "Count Number of Pairs With Absolute Difference K")
-
-## [2005. Subtree Removal Game with Fibonacci Tree (Hard)](https://leetcode.com/problems/subtree-removal-game-with-fibonacci-tree "斐波那契树的移除子树游戏")
-
-
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can game theory help us solve this problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think about the Sprague–Grundy theorem and the Colon Principle
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The Grundy value of a node is the nim sum of the Grundy values of its children.
-</details>
diff --git a/problems/sudoku-solver/README.md b/problems/sudoku-solver/README.md
deleted file mode 100644
index df556e33c..000000000
--- a/problems/sudoku-solver/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-sudoku "Valid Sudoku")
-　　　　　　　　　　　　　　　　
-[Next >](../count-and-say "Count and Say")
-
-## [37. Sudoku Solver (Hard)](https://leetcode.com/problems/sudoku-solver "解数独")
-
-<p>Write a program to solve a Sudoku puzzle by filling the empty cells.</p>
-
-<p>A sudoku solution must satisfy <strong>all of the following rules</strong>:</p>
-
-<ol>
-	<li>Each of the digits <code>1-9</code> must occur exactly once in each row.</li>
-	<li>Each of the digits <code>1-9</code> must occur exactly once in each column.</li>
-	<li>Each of the digits <code>1-9</code> must occur exactly once in each of the 9 <code>3x3</code> sub-boxes of the grid.</li>
-</ol>
-
-<p>The <code>&#39;.&#39;</code> character indicates empty cells.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Sudoku-by-L2G-20050714.svg/250px-Sudoku-by-L2G-20050714.svg.png" style="height:250px; width:250px" />
-<pre>
-<strong>Input:</strong> board = [[&quot;5&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;,&quot;9&quot;,&quot;5&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;9&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;],[&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;3&quot;],[&quot;4&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;],[&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;],[&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;8&quot;,&quot;.&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;4&quot;,&quot;1&quot;,&quot;9&quot;,&quot;.&quot;,&quot;.&quot;,&quot;5&quot;],[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;9&quot;]]
-<strong>Output:</strong> [[&quot;5&quot;,&quot;3&quot;,&quot;4&quot;,&quot;6&quot;,&quot;7&quot;,&quot;8&quot;,&quot;9&quot;,&quot;1&quot;,&quot;2&quot;],[&quot;6&quot;,&quot;7&quot;,&quot;2&quot;,&quot;1&quot;,&quot;9&quot;,&quot;5&quot;,&quot;3&quot;,&quot;4&quot;,&quot;8&quot;],[&quot;1&quot;,&quot;9&quot;,&quot;8&quot;,&quot;3&quot;,&quot;4&quot;,&quot;2&quot;,&quot;5&quot;,&quot;6&quot;,&quot;7&quot;],[&quot;8&quot;,&quot;5&quot;,&quot;9&quot;,&quot;7&quot;,&quot;6&quot;,&quot;1&quot;,&quot;4&quot;,&quot;2&quot;,&quot;3&quot;],[&quot;4&quot;,&quot;2&quot;,&quot;6&quot;,&quot;8&quot;,&quot;5&quot;,&quot;3&quot;,&quot;7&quot;,&quot;9&quot;,&quot;1&quot;],[&quot;7&quot;,&quot;1&quot;,&quot;3&quot;,&quot;9&quot;,&quot;2&quot;,&quot;4&quot;,&quot;8&quot;,&quot;5&quot;,&quot;6&quot;],[&quot;9&quot;,&quot;6&quot;,&quot;1&quot;,&quot;5&quot;,&quot;3&quot;,&quot;7&quot;,&quot;2&quot;,&quot;8&quot;,&quot;4&quot;],[&quot;2&quot;,&quot;8&quot;,&quot;7&quot;,&quot;4&quot;,&quot;1&quot;,&quot;9&quot;,&quot;6&quot;,&quot;3&quot;,&quot;5&quot;],[&quot;3&quot;,&quot;4&quot;,&quot;5&quot;,&quot;2&quot;,&quot;8&quot;,&quot;6&quot;,&quot;1&quot;,&quot;7&quot;,&quot;9&quot;]]
-<strong>Explanation:</strong>&nbsp;The input board is shown above and the only valid solution is shown below:
-
-<img src="https://upload.wikimedia.org/wikipedia/commons/thumb/3/31/Sudoku-by-L2G-20050714_solution.svg/250px-Sudoku-by-L2G-20050714_solution.svg.png" style="height:250px; width:250px" />
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>board.length == 9</code></li>
-	<li><code>board[i].length == 9</code></li>
-	<li><code>board[i][j]</code> is a digit or <code>&#39;.&#39;</code>.</li>
-	<li>It is <strong>guaranteed</strong> that the input board has only one solution.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Valid Sudoku](../valid-sudoku) (Medium)
-  1. [Unique Paths III](../unique-paths-iii) (Hard)
diff --git a/problems/sudoku-solver/sudoku_solver.go b/problems/sudoku-solver/sudoku_solver.go
deleted file mode 100644
index 505c0b445..000000000
--- a/problems/sudoku-solver/sudoku_solver.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem37
diff --git a/problems/sudoku-solver/sudoku_solver_test.go b/problems/sudoku-solver/sudoku_solver_test.go
deleted file mode 100644
index 505c0b445..000000000
--- a/problems/sudoku-solver/sudoku_solver_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem37
diff --git a/problems/sum-game/README.md b/problems/sum-game/README.md
deleted file mode 100644
index 013d6e38e..000000000
--- a/problems/sum-game/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../nearest-exit-from-entrance-in-maze "Nearest Exit from Entrance in Maze")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-reach-destination-in-time "Minimum Cost to Reach Destination in Time")
-
-## [1927. Sum Game (Medium)](https://leetcode.com/problems/sum-game "求和游戏")
-
-<p>Alice and Bob take turns playing a game, with <strong>Alice</strong><strong>&nbsp;starting first</strong>.</p>
-
-<p>You are given a string <code>num</code> of <strong>even length</strong> consisting of digits and <code>&#39;?&#39;</code> characters. On each turn, a player will do the following if there is still at least one <code>&#39;?&#39;</code> in <code>num</code>:</p>
-
-<ol>
-	<li>Choose an index <code>i</code> where <code>num[i] == &#39;?&#39;</code>.</li>
-	<li>Replace <code>num[i]</code> with any digit between <code>&#39;0&#39;</code> and <code>&#39;9&#39;</code>.</li>
-</ol>
-
-<p>The game ends when there are no more <code>&#39;?&#39;</code> characters in <code>num</code>.</p>
-
-<p>For Bob&nbsp;to win, the sum of the digits in the first half of <code>num</code> must be <strong>equal</strong> to the sum of the digits in the second half. For Alice&nbsp;to win, the sums must <strong>not be equal</strong>.</p>
-
-<ul>
-	<li>For example, if the game ended with <code>num = &quot;243801&quot;</code>, then Bob&nbsp;wins because <code>2+4+3 = 8+0+1</code>. If the game ended with <code>num = &quot;243803&quot;</code>, then Alice&nbsp;wins because <code>2+4+3 != 8+0+3</code>.</li>
-</ul>
-
-<p>Assuming Alice and Bob play <strong>optimally</strong>, return <code>true</code> <em>if Alice will win and </em><code>false</code> <em>if Bob will win</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;5023&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> There are no moves to be made.
-The sum of the first half is equal to the sum of the second half: 5 + 0 = 2 + 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;25??&quot;
-<strong>Output:</strong> true
-<strong>Explanation: </strong>Alice can replace one of the &#39;?&#39;s with &#39;9&#39; and it will be impossible for Bob to make the sums equal.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> num = &quot;?3295???&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> It can be proven that Bob will always win. One possible outcome is:
-- Alice replaces the first &#39;?&#39; with &#39;9&#39;. num = &quot;93295???&quot;.
-- Bob replaces one of the &#39;?&#39; in the right half with &#39;9&#39;. num = &quot;932959??&quot;.
-- Alice replaces one of the &#39;?&#39; in the right half with &#39;2&#39;. num = &quot;9329592?&quot;.
-- Bob replaces the last &#39;?&#39; in the right half with &#39;7&#39;. num = &quot;93295927&quot;.
-Bob wins because 9 + 3 + 2 + 9 = 5 + 9 + 2 + 7.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= num.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>num.length</code> is <strong>even</strong>.</li>
-	<li><code>num</code> consists of only digits and <code>&#39;?&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Game Theory](../../tag/game-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Bob can always make the total sum of both sides equal in mod 9.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Why does the difference between the number of question marks on the left and right side matter?
-</details>
diff --git a/problems/sum-of-absolute-differences-in-a-sorted-array/README.md b/problems/sum-of-absolute-differences-in-a-sorted-array/README.md
deleted file mode 100644
index 8d6a3c30c..000000000
--- a/problems/sum-of-absolute-differences-in-a-sorted-array/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-the-number-of-consistent-strings "Count the Number of Consistent Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../stone-game-vi "Stone Game VI")
-
-## [1685. Sum of Absolute Differences in a Sorted Array (Medium)](https://leetcode.com/problems/sum-of-absolute-differences-in-a-sorted-array "有序数组中差绝对值之和")
-
-<p>You are given an integer array <code>nums</code> sorted in <strong>non-decreasing</strong> order.</p>
-
-<p>Build and return <em>an integer array </em><code>result</code><em> with the same length as </em><code>nums</code><em> such that </em><code>result[i]</code><em> is equal to the <strong>summation of absolute differences</strong> between </em><code>nums[i]</code><em> and all the other elements in the array.</em></p>
-
-<p>In other words, <code>result[i]</code> is equal to <code>sum(|nums[i]-nums[j]|)</code> where <code>0 &lt;= j &lt; nums.length</code> and <code>j != i</code> (<strong>0-indexed</strong>).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,5]
-<strong>Output:</strong> [4,3,5]
-<strong>Explanation:</strong> Assuming the arrays are 0-indexed, then
-result[0] = |2-2| + |2-3| + |2-5| = 0 + 1 + 3 = 4,
-result[1] = |3-2| + |3-3| + |3-5| = 1 + 0 + 2 = 3,
-result[2] = |5-2| + |5-3| + |5-5| = 3 + 2 + 0 = 5.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,4,6,8,10]
-<strong>Output:</strong> [24,15,13,15,21]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= nums[i + 1] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Absolute difference is the same as max(a, b) - min(a, b). How can you use this fact with the fact that the array is sorted?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For nums[i], the answer is (nums[i] - nums[0]) + (nums[i] - nums[1]) + ... + (nums[i] - nums[i-1]) + (nums[i+1] - nums[i]) + (nums[i+2] - nums[i]) + ... + (nums[n-1] - nums[i]).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-It can be simplified to (nums[i] * i - (nums[0] + nums[1] + ... + nums[i-1])) + ((nums[i+1] + nums[i+2] + ... + nums[n-1]) - nums[i] * (n-i-1)). One can build prefix and suffix sums to compute  this quickly.
-</details>
diff --git a/problems/sum-of-all-odd-length-subarrays/README.md b/problems/sum-of-all-odd-length-subarrays/README.md
deleted file mode 100644
index 89cc61509..000000000
--- a/problems/sum-of-all-odd-length-subarrays/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bank-account-summary-ii "Bank Account Summary II")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-sum-obtained-of-any-permutation "Maximum Sum Obtained of Any Permutation")
-
-## [1588. Sum of All Odd Length Subarrays (Easy)](https://leetcode.com/problems/sum-of-all-odd-length-subarrays "所有奇数长度子数组的和")
-
-<p>Given an array of positive integers&nbsp;<code>arr</code>, calculate the sum of all possible odd-length subarrays.</p>
-
-<p>A subarray is a contiguous&nbsp;subsequence of the array.</p>
-
-<p>Return&nbsp;<em>the sum of all odd-length subarrays of&nbsp;</em><code>arr</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,4,2,5,3]
-<strong>Output:</strong> 58
-<strong>Explanation: </strong>The odd-length subarrays of arr and their sums are:
-[1] = 1
-[4] = 4
-[2] = 2
-[5] = 5
-[3] = 3
-[1,4,2] = 7
-[4,2,5] = 11
-[2,5,3] = 10
-[1,4,2,5,3] = 15
-If we add all these together we get 1 + 4 + 2 + 5 + 3 + 7 + 11 + 10 + 15 = 58</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2]
-<strong>Output:</strong> 3
-<b>Explanation: </b>There are only 2 subarrays of odd length, [1] and [2]. Their sum is 3.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [10,11,12]
-<strong>Output:</strong> 66
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 100</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can brute force – try every (i,j) pair, and if the length is odd, go through and add the sum to the answer.
-</details>
diff --git a/problems/sum-of-all-subset-xor-totals/README.md b/problems/sum-of-all-subset-xor-totals/README.md
deleted file mode 100644
index 1fa7a407f..000000000
--- a/problems/sum-of-all-subset-xor-totals/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-floored-pairs "Sum of Floored Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-swaps-to-make-the-binary-string-alternating "Minimum Number of Swaps to Make the Binary String Alternating")
-
-## [1863. Sum of All Subset XOR Totals (Easy)](https://leetcode.com/problems/sum-of-all-subset-xor-totals "找出所有子集的异或总和再求和")
-
-<p>The <strong>XOR total</strong> of an array is defined as the bitwise <code>XOR</code> of<strong> all its elements</strong>, or <code>0</code> if the array is<strong> empty</strong>.</p>
-
-<ul>
-	<li>For example, the <strong>XOR total</strong> of the array <code>[2,5,6]</code> is <code>2 XOR 5 XOR 6 = 1</code>.</li>
-</ul>
-
-<p>Given an array <code>nums</code>, return <em>the <strong>sum</strong> of all <strong>XOR totals</strong> for every <strong>subset</strong> of </em><code>nums</code>.&nbsp;</p>
-
-<p><strong>Note:</strong> Subsets with the <strong>same</strong> elements should be counted <strong>multiple</strong> times.</p>
-
-<p>An array <code>a</code> is a <strong>subset</strong> of an array <code>b</code> if <code>a</code> can be obtained from <code>b</code> by deleting some (possibly zero) elements of <code>b</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3]
-<strong>Output:</strong> 6
-<strong>Explanation: </strong>The 4 subsets of [1,3] are:
-- The empty subset has an XOR total of 0.
-- [1] has an XOR total of 1.
-- [3] has an XOR total of 3.
-- [1,3] has an XOR total of 1 XOR 3 = 2.
-0 + 1 + 3 + 2 = 6
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,1,6]
-<strong>Output:</strong> 28
-<strong>Explanation: </strong>The 8 subsets of [5,1,6] are:
-- The empty subset has an XOR total of 0.
-- [5] has an XOR total of 5.
-- [1] has an XOR total of 1.
-- [6] has an XOR total of 6.
-- [5,1] has an XOR total of 5 XOR 1 = 4.
-- [5,6] has an XOR total of 5 XOR 6 = 3.
-- [1,6] has an XOR total of 1 XOR 6 = 7.
-- [5,1,6] has an XOR total of 5 XOR 1 XOR 6 = 2.
-0 + 5 + 1 + 6 + 4 + 3 + 7 + 2 = 28
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,4,5,6,7,8]
-<strong>Output:</strong> 480
-<strong>Explanation:</strong> The sum of all XOR totals for every subset is 480.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 12</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 20</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Is there a way to iterate through all the subsets of the array?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we use recursion to efficiently iterate through all the subsets?
-</details>
diff --git a/problems/sum-of-beauty-in-the-array/README.md b/problems/sum-of-beauty-in-the-array/README.md
deleted file mode 100644
index f6a1c02c1..000000000
--- a/problems/sum-of-beauty-in-the-array/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../final-value-of-variable-after-performing-operations "Final Value of Variable After Performing Operations")
-　　　　　　　　　　　　　　　　
-[Next >](../detect-squares "Detect Squares")
-
-## [2012. Sum of Beauty in the Array (Medium)](https://leetcode.com/problems/sum-of-beauty-in-the-array "数组美丽值求和")
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code>. For each index <code>i</code> (<code>1 &lt;= i &lt;= nums.length - 2</code>) the <strong>beauty</strong> of <code>nums[i]</code> equals:</p>
-
-<ul>
-	<li><code>2</code>, if <code>nums[j] &lt; nums[i] &lt; nums[k]</code>, for <strong>all</strong> <code>0 &lt;= j &lt; i</code> and for <strong>all</strong> <code>i &lt; k &lt;= nums.length - 1</code>.</li>
-	<li><code>1</code>, if <code>nums[i - 1] &lt; nums[i] &lt; nums[i + 1]</code>, and the previous condition is not satisfied.</li>
-	<li><code>0</code>, if none of the previous conditions holds.</li>
-</ul>
-
-<p>Return<em> the <strong>sum of beauty</strong> of all </em><code>nums[i]</code><em> where </em><code>1 &lt;= i &lt;= nums.length - 2</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> For each index i in the range 1 &lt;= i &lt;= 1:
-- The beauty of nums[1] equals 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,4,6,4]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> For each index i in the range 1 &lt;= i &lt;= 2:
-- The beauty of nums[1] equals 1.
-- The beauty of nums[2] equals 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> For each index i in the range 1 &lt;= i &lt;= 1:
-- The beauty of nums[1] equals 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use suffix/prefix arrays.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-prefix[i] records the maximum value in range (0, i - 1) inclusive.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-suffix[i] records the minimum value in range (i + 1, n - 1) inclusive.
-</details>
diff --git a/problems/sum-of-beauty-of-all-substrings/README.md b/problems/sum-of-beauty-of-all-substrings/README.md
deleted file mode 100644
index 8e5cea5de..000000000
--- a/problems/sum-of-beauty-of-all-substrings/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-number-is-a-sum-of-powers-of-three "Check if Number is a Sum of Powers of Three")
-　　　　　　　　　　　　　　　　
-[Next >](../count-pairs-of-nodes "Count Pairs Of Nodes")
-
-## [1781. Sum of Beauty of All Substrings (Medium)](https://leetcode.com/problems/sum-of-beauty-of-all-substrings "所有子字符串美丽值之和")
-
-<p>The <strong>beauty</strong> of a string is the difference in frequencies between the most frequent and least frequent characters.</p>
-
-<ul>
-	<li>For example, the beauty of <code>&quot;abaacc&quot;</code> is <code>3 - 1 = 2</code>.</li>
-</ul>
-
-<p>Given a string <code>s</code>, return <em>the sum of <strong>beauty</strong> of all of its substrings.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabcb&quot;
-<strong>Output:</strong> 5
-<strong>Explanation: </strong>The substrings with non-zero beauty are [&quot;aab&quot;,&quot;aabc&quot;,&quot;aabcb&quot;,&quot;abcb&quot;,&quot;bcb&quot;], each with beauty equal to 1.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabcbaa&quot;
-<strong>Output:</strong> 17
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;=<sup> </sup>500</code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Maintain a prefix sum for the frequencies of characters.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-You can iterate over all substring then iterate over the alphabet and find which character appears most and which appears least using the prefix sum array
-</details>
diff --git a/problems/sum-of-digits-in-base-k/README.md b/problems/sum-of-digits-in-base-k/README.md
deleted file mode 100644
index 8ae9cb78f..000000000
--- a/problems/sum-of-digits-in-base-k/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-duplicates-from-an-unsorted-linked-list "Remove Duplicates From an Unsorted Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../frequency-of-the-most-frequent-element "Frequency of the Most Frequent Element")
-
-## [1837. Sum of Digits in Base K (Easy)](https://leetcode.com/problems/sum-of-digits-in-base-k "K 进制表示下的各位数字总和")
-
-<p>Given an integer <code>n</code> (in base <code>10</code>) and a base <code>k</code>, return <em>the <strong>sum</strong> of the digits of </em><code>n</code><em> <strong>after</strong> converting </em><code>n</code><em> from base </em><code>10</code><em> to base </em><code>k</code>.</p>
-
-<p>After converting, each digit should be interpreted as a base <code>10</code> number, and the sum should be returned in base <code>10</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 34, k = 6
-<strong>Output:</strong> 9
-<strong>Explanation: </strong>34 (base 10) expressed in base 6 is 54. 5 + 4 = 9.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10, k = 10
-<strong>Output:</strong> 1
-<strong>Explanation: </strong>n is already in base 10. 1 + 0 = 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>2 &lt;= k &lt;= 10</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Convert the given number into base k.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use mod-10 to find what each digit is after the conversion and sum the digits.
-</details>
diff --git a/problems/sum-of-digits-in-the-minimum-number/README.md b/problems/sum-of-digits-in-the-minimum-number/README.md
deleted file mode 100644
index c0eb6700d..000000000
--- a/problems/sum-of-digits-in-the-minimum-number/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sales-analysis-iii "Sales Analysis III")
-　　　　　　　　　　　　　　　　
-[Next >](../high-five "High Five")
-
-## [1085. Sum of Digits in the Minimum Number (Easy)](https://leetcode.com/problems/sum-of-digits-in-the-minimum-number "最小元素各数位之和")
-
-<p>Given an array <code>A</code> of positive integers, let <code>S</code> be the sum of the digits of the minimal element of <code>A</code>.</p>
-
-<p>Return 0 if <code>S</code> is odd, otherwise return 1.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-1-1">[34,23,1,24,75,33,54,8]</span>
-<strong>Output: </strong><span id="example-output-1">0</span>
-<strong>Explanation: </strong>
-The minimal element is 1, and the sum of those digits is S = 1 which is odd, so the answer is 0.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong><span id="example-input-2-1">[99,77,33,66,55]</span>
-<strong>Output: </strong><span id="example-output-2">1</span>
-<strong>Explanation: </strong>
-The minimal element is 33, and the sum of those digits is S = 3 + 3 = 6 which is even, so the answer is 1.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= A.length &lt;= 100</code></li>
-	<li><code>1 &lt;= A[i].length &lt;= 100</code></li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Add Digits](../add-digits) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How to find the minimum number in an array?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop over the array and compare each one of the numbers.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How to find the sum of digits?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Divide the number consecutively and get their remainder modulus 10. Sum those remainders and return the answer as the problem asks.
-</details>
diff --git a/problems/sum-of-digits-of-string-after-convert/README.md b/problems/sum-of-digits-of-string-after-convert/README.md
deleted file mode 100644
index a8fba598f..000000000
--- a/problems/sum-of-digits-of-string-after-convert/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-visible-people-in-a-queue "Number of Visible People in a Queue")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-number-after-mutating-substring "Largest Number After Mutating Substring")
-
-## [1945. Sum of Digits of String After Convert (Easy)](https://leetcode.com/problems/sum-of-digits-of-string-after-convert "字符串转化后的各位数字之和")
-
-<p>You are given a string <code>s</code> consisting of lowercase English letters, and an integer <code>k</code>.</p>
-
-<p>First, <strong>convert</strong> <code>s</code> into an integer by replacing each letter with its position in the alphabet (i.e., replace <code>&#39;a&#39;</code> with <code>1</code>, <code>&#39;b&#39;</code> with <code>2</code>, ..., <code>&#39;z&#39;</code> with <code>26</code>). Then, <strong>transform</strong> the integer by replacing it with the <strong>sum of its digits</strong>. Repeat the <strong>transform</strong> operation <code>k</code><strong> times</strong> in total.</p>
-
-<p>For example, if <code>s = &quot;zbax&quot;</code> and <code>k = 2</code>, then the resulting integer would be <code>8</code> by the following operations:</p>
-
-<ul>
-	<li><strong>Convert</strong>: <code>&quot;zbax&quot; ➝ &quot;(26)(2)(1)(24)&quot; ➝ &quot;262124&quot; ➝ 262124</code></li>
-	<li><strong>Transform #1</strong>: <code>262124 ➝ 2 + 6 + 2 + 1 + 2 + 4&nbsp;➝ 17</code></li>
-	<li><strong>Transform #2</strong>: <code>17 ➝ 1 + 7 ➝ 8</code></li>
-</ul>
-
-<p>Return <em>the resulting integer after performing the operations described above</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;iiii&quot;, k = 1
-<strong>Output:</strong> 36
-<strong>Explanation:</strong> The operations are as follows:
-- Convert: &quot;iiii&quot; ➝ &quot;(9)(9)(9)(9)&quot; ➝ &quot;9999&quot; ➝ 9999
-- Transform #1: 9999 ➝ 9 + 9 + 9 + 9 ➝ 36
-Thus the resulting integer is 36.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;, k = 2
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The operations are as follows:
-- Convert: &quot;leetcode&quot; ➝ &quot;(12)(5)(5)(20)(3)(15)(4)(5)&quot; ➝ &quot;12552031545&quot; ➝ 12552031545
-- Transform #1: 12552031545 ➝ 1 + 2 + 5 + 5 + 2 + 0 + 3 + 1 + 5 + 4 + 5 ➝ 33
-- Transform #2: 33 ➝ 3 + 3 ➝ 6
-Thus the resulting integer is 6.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;zbax&quot;, k = 2
-<strong>Output:</strong> 8
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>1 &lt;= k &lt;= 10</code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-First, let's note that after the first transform the value will be at most 100 * 9 which is not much
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After The first transform, we can just do the rest of the transforms by brute force
-</details>
diff --git a/problems/sum-of-distances-in-tree/README.md b/problems/sum-of-distances-in-tree/README.md
deleted file mode 100644
index 470093066..000000000
--- a/problems/sum-of-distances-in-tree/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-and-replace-in-string "Find And Replace in String")
-　　　　　　　　　　　　　　　　
-[Next >](../image-overlap "Image Overlap")
-
-## [834. Sum of Distances in Tree (Hard)](https://leetcode.com/problems/sum-of-distances-in-tree "树中距离之和")
-
-<p>There is an undirected connected tree with <code>n</code> nodes labeled from <code>0</code> to <code>n - 1</code> and <code>n - 1</code> edges.</p>
-
-<p>You are given the integer <code>n</code> and the array <code>edges</code> where <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that there is an edge between nodes <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code> in the tree.</p>
-
-<p>Return an array <code>answer</code> of length <code>n</code> where <code>answer[i]</code> is the sum of the distances between the <code>i<sup>th</sup></code> node in the tree and all other nodes.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-sumdist1.jpg" style="width: 304px; height: 224px;" />
-<pre>
-<strong>Input:</strong> n = 6, edges = [[0,1],[0,2],[2,3],[2,4],[2,5]]
-<strong>Output:</strong> [8,12,6,10,10,10]
-<strong>Explanation:</strong> The tree is shown above.
-We can see that dist(0,1) + dist(0,2) + dist(0,3) + dist(0,4) + dist(0,5)
-equals 1 + 1 + 2 + 2 + 2 = 8.
-Hence, answer[0] = 8, and so on.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-sumdist2.jpg" style="width: 64px; height: 65px;" />
-<pre>
-<strong>Input:</strong> n = 1, edges = []
-<strong>Output:</strong> [0]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-sumdist3.jpg" style="width: 144px; height: 145px;" />
-<pre>
-<strong>Input:</strong> n = 2, edges = [[1,0]]
-<strong>Output:</strong> [1,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>edges.length == n - 1</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt; n</code></li>
-	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
-	<li>The given input represents a valid tree.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Distribute Coins in Binary Tree](../distribute-coins-in-binary-tree) (Medium)
diff --git a/problems/sum-of-distances-in-tree/sum_of_distances_in_tree.go b/problems/sum-of-distances-in-tree/sum_of_distances_in_tree.go
deleted file mode 100644
index 156f05210..000000000
--- a/problems/sum-of-distances-in-tree/sum_of_distances_in_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem834
diff --git a/problems/sum-of-distances-in-tree/sum_of_distances_in_tree_test.go b/problems/sum-of-distances-in-tree/sum_of_distances_in_tree_test.go
deleted file mode 100644
index 156f05210..000000000
--- a/problems/sum-of-distances-in-tree/sum_of_distances_in_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem834
diff --git a/problems/sum-of-even-numbers-after-queries/README.md b/problems/sum-of-even-numbers-after-queries/README.md
deleted file mode 100644
index 392687112..000000000
--- a/problems/sum-of-even-numbers-after-queries/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../string-without-aaa-or-bbb "String Without AAA or BBB")
-　　　　　　　　　　　　　　　　
-[Next >](../interval-list-intersections "Interval List Intersections")
-
-## [985. Sum of Even Numbers After Queries (Medium)](https://leetcode.com/problems/sum-of-even-numbers-after-queries "查询后的偶数和")
-
-<p>You are given an integer array <code>nums</code> and an array <code>queries</code> where <code>queries[i] = [val<sub>i</sub>, index<sub>i</sub>]</code>.</p>
-
-<p>For each query <code>i</code>, first, apply <code>nums[index<sub>i</sub>] = nums[index<sub>i</sub>] + val<sub>i</sub></code>, then print the sum of the even values of <code>nums</code>.</p>
-
-<p>Return <em>an integer array </em><code>answer</code><em> where </em><code>answer[i]</code><em> is the answer to the </em><code>i<sup>th</sup></code><em> query</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4], queries = [[1,0],[-3,1],[-4,0],[2,3]]
-<strong>Output:</strong> [8,6,2,4]
-<strong>Explanation:</strong> At the beginning, the array is [1,2,3,4].
-After adding 1 to nums[0], the array is [2,2,3,4], and the sum of even values is 2 + 2 + 4 = 8.
-After adding -3 to nums[1], the array is [2,-1,3,4], and the sum of even values is 2 + 4 = 6.
-After adding -4 to nums[0], the array is [-2,-1,3,4], and the sum of even values is -2 + 4 = 2.
-After adding 2 to nums[3], the array is [-2,-1,3,6], and the sum of even values is -2 + 6 = 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1], queries = [[4,0]]
-<strong>Output:</strong> [0]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= queries.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>4</sup> &lt;= val<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= index<sub>i</sub> &lt; nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/sum-of-even-numbers-after-queries/sum_of_even_numbers_after_queries.go b/problems/sum-of-even-numbers-after-queries/sum_of_even_numbers_after_queries.go
deleted file mode 100644
index 87dff26b9..000000000
--- a/problems/sum-of-even-numbers-after-queries/sum_of_even_numbers_after_queries.go
+++ /dev/null
@@ -1,22 +0,0 @@
-package problem985
-
-func sumEvenAfterQueries(A []int, queries [][]int) []int {
-	sum, ans := 0, make([]int, 0)
-	for _, v := range A {
-		if v%2 == 0 {
-			sum += v
-		}
-	}
-	for _, q := range queries {
-		v, i := q[0], q[1]
-		if A[i]%2 == 0 {
-			sum -= A[i]
-		}
-		A[i] += v
-		if A[i]%2 == 0 {
-			sum += A[i]
-		}
-		ans = append(ans, sum)
-	}
-	return ans
-}
diff --git a/problems/sum-of-even-numbers-after-queries/sum_of_even_numbers_after_queries_test.go b/problems/sum-of-even-numbers-after-queries/sum_of_even_numbers_after_queries_test.go
deleted file mode 100644
index a6c1791ad..000000000
--- a/problems/sum-of-even-numbers-after-queries/sum_of_even_numbers_after_queries_test.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package problem985
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in      []int
-	queries [][]int
-	want    []int
-}
-
-func TestSumEvenAfterQueries(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:      []int{1, 2, 3, 4},
-			queries: [][]int{{1, 0}, {-3, 1}, {-4, 0}, {2, 3}},
-			want:    []int{8, 6, 2, 4},
-		},
-	}
-	for _, tt := range tests {
-		got := sumEvenAfterQueries(tt.in, tt.queries)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/sum-of-floored-pairs/README.md b/problems/sum-of-floored-pairs/README.md
deleted file mode 100644
index 10d72bc34..000000000
--- a/problems/sum-of-floored-pairs/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rotating-the-box "Rotating the Box")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-all-subset-xor-totals "Sum of All Subset XOR Totals")
-
-## [1862. Sum of Floored Pairs (Hard)](https://leetcode.com/problems/sum-of-floored-pairs "向下取整数对和")
-
-<p>Given an integer array <code>nums</code>, return the sum of <code>floor(nums[i] / nums[j])</code> for all pairs of indices <code>0 &lt;= i, j &lt; nums.length</code> in the array. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>The <code>floor()</code> function returns the integer part of the division.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,5,9]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong>
-floor(2 / 5) = floor(2 / 9) = floor(5 / 9) = 0
-floor(2 / 2) = floor(5 / 5) = floor(9 / 9) = 1
-floor(5 / 2) = 2
-floor(9 / 2) = 4
-floor(9 / 5) = 1
-We calculate the floor of the division for every pair of indices in the array then sum them up.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [7,7,7,7,7,7,7]
-<strong>Output:</strong> 49
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the frequency (number of occurrences) of all elements in the array.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each element, iterate through its multiples and multiply frequencies to find the answer.
-</details>
diff --git a/problems/sum-of-k-mirror-numbers/README.md b/problems/sum-of-k-mirror-numbers/README.md
deleted file mode 100644
index 3d18182e4..000000000
--- a/problems/sum-of-k-mirror-numbers/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-frequency-queries "Range Frequency Queries")
-　　　　　　　　　　　　　　　　
-[Next >](../the-number-of-rich-customers "The Number of Rich Customers")
-
-## [2081. Sum of k-Mirror Numbers (Hard)](https://leetcode.com/problems/sum-of-k-mirror-numbers "k 镜像数字的和")
-
-<p>A <strong>k-mirror number</strong> is a <strong>positive</strong> integer <strong>without leading zeros</strong> that reads the same both forward and backward in base-10 <strong>as well as</strong> in base-k.</p>
-
-<ul>
-	<li>For example, <code>9</code> is a 2-mirror number. The representation of <code>9</code> in base-10 and base-2 are <code>9</code> and <code>1001</code> respectively, which read the same both forward and backward.</li>
-	<li>On the contrary, <code>4</code> is not a 2-mirror number. The representation of <code>4</code> in base-2 is <code>100</code>, which does not read the same both forward and backward.</li>
-</ul>
-
-<p>Given the base <code>k</code> and the number <code>n</code>, return <em>the <strong>sum</strong> of the</em> <code>n</code> <em><strong>smallest</strong> k-mirror numbers</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 2, n = 5
-<strong>Output:</strong> 25
-<strong>Explanation:
-</strong>The 5 smallest 2-mirror numbers and their representations in base-2 are listed as follows:
-  base-10    base-2
-    1          1
-    3          11
-    5          101
-    7          111
-    9          1001
-Their sum = 1 + 3 + 5 + 7 + 9 = 25. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3, n = 7
-<strong>Output:</strong> 499
-<strong>Explanation:
-</strong>The 7 smallest 3-mirror numbers are and their representations in base-3 are listed as follows:
-  base-10    base-3
-    1          1
-    2          2
-    4          11
-    8          22
-    121        11111
-    151        12121
-    212        21212
-Their sum = 1 + 2 + 4 + 8 + 121 + 151 + 212 = 499.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 7, n = 17
-<strong>Output:</strong> 20379000
-<strong>Explanation:</strong> The 17 smallest 7-mirror numbers are:
-1, 2, 3, 4, 5, 6, 8, 121, 171, 242, 292, 16561, 65656, 2137312, 4602064, 6597956, 6958596
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= k &lt;= 9</code></li>
-	<li><code>1 &lt;= n &lt;= 30</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since we need to reduce search space, instead of checking if every number is a palindrome in base-10, can we try to "generate" the palindromic numbers?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you are provided with a d digit number, how can you generate a palindrome with 2*d or 2*d - 1 digit?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Try brute-forcing and checking if the palindrome you generated is a "k-Mirror" number.
-</details>
diff --git a/problems/sum-of-left-leaves/README.md b/problems/sum-of-left-leaves/README.md
deleted file mode 100644
index 232f68a07..000000000
--- a/problems/sum-of-left-leaves/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../frog-jump "Frog Jump")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-a-number-to-hexadecimal "Convert a Number to Hexadecimal")
-
-## [404. Sum of Left Leaves (Easy)](https://leetcode.com/problems/sum-of-left-leaves "左叶子之和")
-
-<p>Given the <code>root</code> of a binary tree, return the sum of all left leaves.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/leftsum-tree.jpg" style="width: 277px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,null,null,15,7]
-<strong>Output:</strong> 24
-<strong>Explanation:</strong> There are two left leaves in the binary tree, with values 9 and 15 respectively.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 1000]</code>.</li>
-	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/sum-of-left-leaves/sum_of_left_leaves.go b/problems/sum-of-left-leaves/sum_of_left_leaves.go
deleted file mode 100644
index 331c9439c..000000000
--- a/problems/sum-of-left-leaves/sum_of_left_leaves.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem404
diff --git a/problems/sum-of-left-leaves/sum_of_left_leaves_test.go b/problems/sum-of-left-leaves/sum_of_left_leaves_test.go
deleted file mode 100644
index 331c9439c..000000000
--- a/problems/sum-of-left-leaves/sum_of_left_leaves_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem404
diff --git a/problems/sum-of-mutated-array-closest-to-target/README.md b/problems/sum-of-mutated-array-closest-to-target/README.md
deleted file mode 100644
index 490eaebb2..000000000
--- a/problems/sum-of-mutated-array-closest-to-target/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../replace-elements-with-greatest-element-on-right-side "Replace Elements with Greatest Element on Right Side")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-paths-with-max-score "Number of Paths with Max Score")
-
-## [1300. Sum of Mutated Array Closest to Target (Medium)](https://leetcode.com/problems/sum-of-mutated-array-closest-to-target "转变数组后最接近目标值的数组和")
-
-<p>Given an integer array <code>arr</code> and a target value <code>target</code>, return the integer <code>value</code> such that when we change all the integers larger than <code>value</code> in the given array to be equal to <code>value</code>, the sum of the array gets as close as possible (in absolute difference) to <code>target</code>.</p>
-
-<p>In case of a tie, return the minimum such integer.</p>
-
-<p>Notice that the answer is not neccesarilly a number from <code>arr</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,9,3], target = 10
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> When using 3 arr converts to [3, 3, 3] which sums 9 and that&#39;s the optimal answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,3,5], target = 10
-<strong>Output:</strong> 5
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [60864,25176,27249,21296,20204], target = 56803
-<strong>Output:</strong> 11361
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= arr[i], target &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-If you draw a graph with the value on one axis and the absolute difference between the target and the array sum, what will you get?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-That graph is uni-modal.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use ternary search on that graph to find the best value.
-</details>
diff --git a/problems/sum-of-nodes-with-even-valued-grandparent/README.md b/problems/sum-of-nodes-with-even-valued-grandparent/README.md
deleted file mode 100644
index fdcf237f6..000000000
--- a/problems/sum-of-nodes-with-even-valued-grandparent/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../matrix-block-sum "Matrix Block Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../distinct-echo-substrings "Distinct Echo Substrings")
-
-## [1315. Sum of Nodes with Even-Valued Grandparent (Medium)](https://leetcode.com/problems/sum-of-nodes-with-even-valued-grandparent "祖父节点值为偶数的节点和")
-
-<p>Given the <code>root</code> of a binary tree, return <em>the sum of values of nodes with an <strong>even-valued grandparent</strong></em>. If there are no nodes with an <strong>even-valued grandparent</strong>, return <code>0</code>.</p>
-
-<p>A <strong>grandparent</strong> of a node is the parent of its parent if it exists.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/10/even1-tree.jpg" style="width: 504px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5]
-<strong>Output:</strong> 18
-<strong>Explanation:</strong> The red nodes are the nodes with even-value grandparent while the blue nodes are the even-value grandparents.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/10/even2-tree.jpg" style="width: 64px; height: 65px;" />
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Traverse the tree keeping the parent and the grandparent.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the grandparent of the current node is even-valued, add the value of this node to the answer.
-</details>
diff --git a/problems/sum-of-root-to-leaf-binary-numbers/README.md b/problems/sum-of-root-to-leaf-binary-numbers/README.md
deleted file mode 100644
index b74243c58..000000000
--- a/problems/sum-of-root-to-leaf-binary-numbers/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-outermost-parentheses "Remove Outermost Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../camelcase-matching "Camelcase Matching")
-
-## [1022. Sum of Root To Leaf Binary Numbers (Easy)](https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers "从根到叶的二进制数之和")
-
-<p>You are given the <code>root</code> of a binary tree where each node has a value <code>0</code>&nbsp;or <code>1</code>.&nbsp; Each root-to-leaf path represents a binary number starting with the most significant bit.&nbsp; For example, if the path is <code>0 -&gt; 1 -&gt; 1 -&gt; 0 -&gt; 1</code>, then this could represent <code>01101</code> in binary, which is <code>13</code>.</p>
-
-<p>For all leaves in the tree, consider the numbers represented by the path&nbsp;from the root to that leaf.</p>
-
-<p>Return <em>the sum of these numbers</em>. The answer is <strong>guaranteed</strong> to fit in a <strong>32-bits</strong> integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/04/04/sum-of-root-to-leaf-binary-numbers.png" style="width: 450px; height: 296px;" />
-<pre>
-<strong>Input:</strong> root = [1,0,1,0,1,0,1]
-<strong>Output:</strong> 22
-<strong>Explanation: </strong>(100) + (101) + (110) + (111) = 4 + 5 + 6 + 7 = 22
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [0]
-<strong>Output:</strong> 0
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1]
-<strong>Output:</strong> 1
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,1]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 1000]</code>.</li>
-	<li><code>Node.val</code> is <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find each path, then transform that path to an integer in base 10.
-</details>
diff --git a/problems/sum-of-root-to-leaf-binary-numbers/sum_of_root_to_leaf_binary_numbers.go b/problems/sum-of-root-to-leaf-binary-numbers/sum_of_root_to_leaf_binary_numbers.go
deleted file mode 100644
index 5ee19e766..000000000
--- a/problems/sum-of-root-to-leaf-binary-numbers/sum_of_root_to_leaf_binary_numbers.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem1022
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func sumRootToLeaf(root *TreeNode) int {
-	if root.Left == nil && root.Right == nil {
-		return root.Val
-	}
-	sum := 0
-	if root.Left != nil {
-		root.Left.Val += root.Val << 1
-		sum += sumRootToLeaf(root.Left)
-	}
-	if root.Right != nil {
-		root.Right.Val += root.Val << 1
-		sum += sumRootToLeaf(root.Right)
-	}
-	return sum
-}
diff --git a/problems/sum-of-root-to-leaf-binary-numbers/sum_of_root_to_leaf_binary_numbers_test.go b/problems/sum-of-root-to-leaf-binary-numbers/sum_of_root_to_leaf_binary_numbers_test.go
deleted file mode 100644
index d75ed8f38..000000000
--- a/problems/sum-of-root-to-leaf-binary-numbers/sum_of_root_to_leaf_binary_numbers_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1022
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestSumRootToLeaf(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 0, 1, 0, 1, 0, 1},
-			want: 22,
-		},
-		{
-			in:   []int{1, 1},
-			want: 3,
-		},
-		{
-			in:   []int{1, kit.NULL, 0},
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := sumRootToLeaf(kit.SliceInt2TreeNode(tt.in))
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/sum-of-special-evenly-spaced-elements-in-array/README.md b/problems/sum-of-special-evenly-spaced-elements-in-array/README.md
deleted file mode 100644
index 0ef13bf98..000000000
--- a/problems/sum-of-special-evenly-spaced-elements-in-array/README.md
+++ /dev/null
@@ -1,34 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-operations-to-make-a-subsequence "Minimum Operations to Make a Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../count-apples-and-oranges "Count Apples and Oranges")
-
-## [1714. Sum Of Special Evenly-Spaced Elements In Array (Hard)](https://leetcode.com/problems/sum-of-special-evenly-spaced-elements-in-array "数组中特殊等间距元素的和")
-
-
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think if y cannot be small. You can solve a query in O(n/y), so if y is large enough, it won't be a problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If y is small, like less than B, you can preprocess the answers for all such ys in O(n * B), then answer each such query in O(1).
-</details>
-
-<details>
-<summary>Hint 3</summary>
-As you might have already guessed, the optimal value for B is ~sqrt(n).
-</details>
diff --git a/problems/sum-of-square-numbers/README.md b/problems/sum-of-square-numbers/README.md
deleted file mode 100644
index bdd0de9dd..000000000
--- a/problems/sum-of-square-numbers/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-range-covering-elements-from-k-lists "Smallest Range Covering Elements from K Lists")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-derangement-of-an-array "Find the Derangement of An Array")
-
-## [633. Sum of Square Numbers (Medium)](https://leetcode.com/problems/sum-of-square-numbers "平方数之和")
-
-<p>Given a non-negative integer <code>c</code>, decide whether there&#39;re two integers <code>a</code> and <code>b</code> such that <code>a<sup>2</sup> + b<sup>2</sup> = c</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> c = 5
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 1 * 1 + 2 * 2 = 5
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> c = 3
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= c &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Valid Perfect Square](../valid-perfect-square) (Easy)
diff --git a/problems/sum-of-square-numbers/sum_of_square_numbers.go b/problems/sum-of-square-numbers/sum_of_square_numbers.go
deleted file mode 100644
index 762b3a260..000000000
--- a/problems/sum-of-square-numbers/sum_of_square_numbers.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem633
diff --git a/problems/sum-of-square-numbers/sum_of_square_numbers_test.go b/problems/sum-of-square-numbers/sum_of_square_numbers_test.go
deleted file mode 100644
index 762b3a260..000000000
--- a/problems/sum-of-square-numbers/sum_of_square_numbers_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem633
diff --git a/problems/sum-of-subarray-minimums/README.md b/problems/sum-of-subarray-minimums/README.md
deleted file mode 100644
index ee1e208f7..000000000
--- a/problems/sum-of-subarray-minimums/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../super-palindromes "Super Palindromes")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-range-i "Smallest Range I")
-
-## [907. Sum of Subarray Minimums (Medium)](https://leetcode.com/problems/sum-of-subarray-minimums "子数组的最小值之和")
-
-<p>Given an array of integers arr, find the sum of <code>min(b)</code>, where <code>b</code> ranges over every (contiguous) subarray of <code>arr</code>. Since the answer may be large, return the answer <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [3,1,2,4]
-<strong>Output:</strong> 17
-<strong>Explanation:</strong> 
-Subarrays are [3], [1], [2], [4], [3,1], [1,2], [2,4], [3,1,2], [1,2,4], [3,1,2,4]. 
-Minimums are 3, 1, 2, 4, 1, 1, 2, 1, 1, 1.
-Sum is 17.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [11,81,94,43,3]
-<strong>Output:</strong> 444
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 3 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
diff --git a/problems/sum-of-subarray-minimums/sum_of_subarray_minimums.go b/problems/sum-of-subarray-minimums/sum_of_subarray_minimums.go
deleted file mode 100644
index 340083963..000000000
--- a/problems/sum-of-subarray-minimums/sum_of_subarray_minimums.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem907
diff --git a/problems/sum-of-subarray-minimums/sum_of_subarray_minimums_test.go b/problems/sum-of-subarray-minimums/sum_of_subarray_minimums_test.go
deleted file mode 100644
index 340083963..000000000
--- a/problems/sum-of-subarray-minimums/sum_of_subarray_minimums_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem907
diff --git a/problems/sum-of-subarray-ranges/README.md b/problems/sum-of-subarray-ranges/README.md
deleted file mode 100644
index 78e5d4cbd..000000000
--- a/problems/sum-of-subarray-ranges/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rings-and-rods "Rings and Rods")
-　　　　　　　　　　　　　　　　
-[Next >](../watering-plants-ii "Watering Plants II")
-
-## [2104. Sum of Subarray Ranges (Medium)](https://leetcode.com/problems/sum-of-subarray-ranges "子数组范围和")
-
-<p>You are given an integer array <code>nums</code>. The <strong>range</strong> of a subarray of <code>nums</code> is the difference between the largest and smallest element in the subarray.</p>
-
-<p>Return <em>the <strong>sum of all</strong> subarray ranges of </em><code>nums</code><em>.</em></p>
-
-<p>A subarray is a contiguous <strong>non-empty</strong> sequence of elements within an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The 6 subarrays of nums are the following:
-[1], range = largest - smallest = 1 - 1 = 0 
-[2], range = 2 - 2 = 0
-[3], range = 3 - 3 = 0
-[1,2], range = 2 - 1 = 1
-[2,3], range = 3 - 2 = 1
-[1,2,3], range = 3 - 1 = 2
-So the sum of all ranges is 0 + 0 + 0 + 1 + 1 + 2 = 4.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,3]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The 6 subarrays of nums are the following:
-[1], range = largest - smallest = 1 - 1 = 0
-[3], range = 3 - 3 = 0
-[3], range = 3 - 3 = 0
-[1,3], range = 3 - 1 = 2
-[3,3], range = 3 - 3 = 0
-[1,3,3], range = 3 - 1 = 2
-So the sum of all ranges is 0 + 0 + 0 + 2 + 0 + 2 = 4.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,-2,-3,4,1]
-<strong>Output:</strong> 59
-<strong>Explanation:</strong> The sum of all subarray ranges of nums is 59.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow-up:</strong> Could you find a solution with <code>O(n)</code> time complexity?</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you get the max/min of a certain subarray by using the max/min of a smaller subarray within it?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Notice that the max of the subarray from index i to j is equal to max of (max of the subarray from index i to j-1) and nums[j].
-</details>
diff --git a/problems/sum-of-subsequence-widths/README.md b/problems/sum-of-subsequence-widths/README.md
deleted file mode 100644
index 237896b1c..000000000
--- a/problems/sum-of-subsequence-widths/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-and-replace-pattern "Find and Replace Pattern")
-　　　　　　　　　　　　　　　　
-[Next >](../surface-area-of-3d-shapes "Surface Area of 3D Shapes")
-
-## [891. Sum of Subsequence Widths (Hard)](https://leetcode.com/problems/sum-of-subsequence-widths "子序列宽度之和")
-
-<p>The <strong>width</strong> of a sequence is the difference between the maximum and minimum elements in the sequence.</p>
-
-<p>Given an array of integers <code>nums</code>, return <em>the sum of the <strong>widths</strong> of all the non-empty <strong>subsequences</strong> of </em><code>nums</code>. Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>A <strong>subsequence</strong> is a sequence that can be derived from an array by deleting some or no elements without changing the order of the remaining elements. For example, <code>[3,6,2,7]</code> is a subsequence of the array <code>[0,3,1,6,2,2,7]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,3]
-<strong>Output:</strong> 6
-Explanation: The subsequences are [1], [2], [3], [2,1], [2,3], [1,3], [2,1,3].
-The corresponding widths are 0, 0, 0, 1, 1, 2, 2.
-The sum of these widths is 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2]
-<strong>Output:</strong> 0
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/sum-of-subsequence-widths/sum_of_subsequence_widths.go b/problems/sum-of-subsequence-widths/sum_of_subsequence_widths.go
deleted file mode 100644
index 7caef272a..000000000
--- a/problems/sum-of-subsequence-widths/sum_of_subsequence_widths.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem891
diff --git a/problems/sum-of-subsequence-widths/sum_of_subsequence_widths_test.go b/problems/sum-of-subsequence-widths/sum_of_subsequence_widths_test.go
deleted file mode 100644
index 7caef272a..000000000
--- a/problems/sum-of-subsequence-widths/sum_of_subsequence_widths_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem891
diff --git a/problems/sum-of-two-integers/README.md b/problems/sum-of-two-integers/README.md
deleted file mode 100644
index e697240ee..000000000
--- a/problems/sum-of-two-integers/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../range-addition "Range Addition")
-　　　　　　　　　　　　　　　　
-[Next >](../super-pow "Super Pow")
-
-## [371. Sum of Two Integers (Medium)](https://leetcode.com/problems/sum-of-two-integers "两整数之和")
-
-<p>Given two integers <code>a</code> and <code>b</code>, return <em>the sum of the two integers without using the operators</em> <code>+</code> <em>and</em> <code>-</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> a = 1, b = 2
-<strong>Output:</strong> 3
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> a = 2, b = 3
-<strong>Output:</strong> 5
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-1000 &lt;= a, b &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Add Two Numbers](../add-two-numbers) (Medium)
diff --git a/problems/sum-of-two-integers/sum_of_two_integers.go b/problems/sum-of-two-integers/sum_of_two_integers.go
deleted file mode 100644
index 7a55321bb..000000000
--- a/problems/sum-of-two-integers/sum_of_two_integers.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package problem371
-
-func getSum(a int, b int) int {
-	for b != 0 {
-		a, b = a^b, (a&b)<<1
-	}
-	return a
-}
diff --git a/problems/sum-of-two-integers/sum_of_two_integers_test.go b/problems/sum-of-two-integers/sum_of_two_integers_test.go
deleted file mode 100644
index 970bc7c1d..000000000
--- a/problems/sum-of-two-integers/sum_of_two_integers_test.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package problem371
-
-import "testing"
-
-type testType struct {
-	a    int
-	b    int
-	want int
-}
-
-func TestGetSum(t *testing.T) {
-	tests := [...]testType{
-		{
-			a:    1,
-			b:    2,
-			want: 3,
-		},
-		{
-			a:    -2,
-			b:    3,
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := getSum(tt.a, tt.b)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.a, tt.b, got, tt.want)
-		}
-	}
-}
diff --git a/problems/sum-of-unique-elements/README.md b/problems/sum-of-unique-elements/README.md
deleted file mode 100644
index b4d997c06..000000000
--- a/problems/sum-of-unique-elements/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../leetflex-banned-accounts "Leetflex Banned Accounts")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-absolute-sum-of-any-subarray "Maximum Absolute Sum of Any Subarray")
-
-## [1748. Sum of Unique Elements (Easy)](https://leetcode.com/problems/sum-of-unique-elements "唯一元素的和")
-
-<p>You are given an integer array <code>nums</code>. The unique elements of an array are the elements that appear <strong>exactly once</strong> in the array.</p>
-
-<p>Return <em>the <strong>sum</strong> of all the unique elements of </em><code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,2]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The unique elements are [1,3], and the sum is 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,1,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no unique elements, and the sum is 0.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5]
-<strong>Output:</strong> 15
-<strong>Explanation:</strong> The unique elements are [1,2,3,4,5], and the sum is 15.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use a dictionary to count the frequency of each number.
-</details>
diff --git a/problems/sum-root-to-leaf-numbers/README.md b/problems/sum-root-to-leaf-numbers/README.md
deleted file mode 100644
index 808108913..000000000
--- a/problems/sum-root-to-leaf-numbers/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-consecutive-sequence "Longest Consecutive Sequence")
-　　　　　　　　　　　　　　　　
-[Next >](../surrounded-regions "Surrounded Regions")
-
-## [129. Sum Root to Leaf Numbers (Medium)](https://leetcode.com/problems/sum-root-to-leaf-numbers "求根节点到叶节点数字之和")
-
-<p>You are given the <code>root</code> of a binary tree containing digits from <code>0</code> to <code>9</code> only.</p>
-
-<p>Each root-to-leaf path in the tree represents a number.</p>
-
-<ul>
-	<li>For example, the root-to-leaf path <code>1 -&gt; 2 -&gt; 3</code> represents the number <code>123</code>.</li>
-</ul>
-
-<p>Return <em>the total sum of all root-to-leaf numbers</em>. Test cases are generated so that the answer will fit in a <strong>32-bit</strong> integer.</p>
-
-<p>A <strong>leaf</strong> node is a node with no children.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/num1tree.jpg" style="width: 212px; height: 182px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3]
-<strong>Output:</strong> 25
-<strong>Explanation:</strong>
-The root-to-leaf path <code>1-&gt;2</code> represents the number <code>12</code>.
-The root-to-leaf path <code>1-&gt;3</code> represents the number <code>13</code>.
-Therefore, sum = 12 + 13 = <code>25</code>.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/num2tree.jpg" style="width: 292px; height: 302px;" />
-<pre>
-<strong>Input:</strong> root = [4,9,0,5,1]
-<strong>Output:</strong> 1026
-<strong>Explanation:</strong>
-The root-to-leaf path <code>4-&gt;9-&gt;5</code> represents the number 495.
-The root-to-leaf path <code>4-&gt;9-&gt;1</code> represents the number 491.
-The root-to-leaf path <code>4-&gt;0</code> represents the number 40.
-Therefore, sum = 495 + 491 + 40 = <code>1026</code>.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 1000]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 9</code></li>
-	<li>The depth of the tree will not exceed <code>10</code>.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Path Sum](../path-sum) (Easy)
-  1. [Binary Tree Maximum Path Sum](../binary-tree-maximum-path-sum) (Hard)
-  1. [Smallest String Starting From Leaf](../smallest-string-starting-from-leaf) (Medium)
diff --git a/problems/sum-root-to-leaf-numbers/sum_root_to_leaf_numbers.go b/problems/sum-root-to-leaf-numbers/sum_root_to_leaf_numbers.go
deleted file mode 100644
index b214f2940..000000000
--- a/problems/sum-root-to-leaf-numbers/sum_root_to_leaf_numbers.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem129
diff --git a/problems/sum-root-to-leaf-numbers/sum_root_to_leaf_numbers_test.go b/problems/sum-root-to-leaf-numbers/sum_root_to_leaf_numbers_test.go
deleted file mode 100644
index b214f2940..000000000
--- a/problems/sum-root-to-leaf-numbers/sum_root_to_leaf_numbers_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem129
diff --git a/problems/summary-ranges/README.md b/problems/summary-ranges/README.md
deleted file mode 100644
index f9d073e35..000000000
--- a/problems/summary-ranges/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../basic-calculator-ii "Basic Calculator II")
-　　　　　　　　　　　　　　　　
-[Next >](../majority-element-ii "Majority Element II")
-
-## [228. Summary Ranges (Easy)](https://leetcode.com/problems/summary-ranges "汇总区间")
-
-<p>You are given a <strong>sorted unique</strong> integer array <code>nums</code>.</p>
-
-<p>Return <em>the <strong>smallest sorted</strong> list of ranges that <strong>cover all the numbers in the array exactly</strong></em>. That is, each element of <code>nums</code> is covered by exactly one of the ranges, and there is no integer <code>x</code> such that <code>x</code> is in one of the ranges but not in <code>nums</code>.</p>
-
-<p>Each range <code>[a,b]</code> in the list should be output as:</p>
-
-<ul>
-	<li><code>&quot;a-&gt;b&quot;</code> if <code>a != b</code></li>
-	<li><code>&quot;a&quot;</code> if <code>a == b</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,1,2,4,5,7]
-<strong>Output:</strong> [&quot;0-&gt;2&quot;,&quot;4-&gt;5&quot;,&quot;7&quot;]
-<strong>Explanation:</strong> The ranges are:
-[0,2] --&gt; &quot;0-&gt;2&quot;
-[4,5] --&gt; &quot;4-&gt;5&quot;
-[7,7] --&gt; &quot;7&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,2,3,4,6,8,9]
-<strong>Output:</strong> [&quot;0&quot;,&quot;2-&gt;4&quot;,&quot;6&quot;,&quot;8-&gt;9&quot;]
-<strong>Explanation:</strong> The ranges are:
-[0,0] --&gt; &quot;0&quot;
-[2,4] --&gt; &quot;2-&gt;4&quot;
-[6,6] --&gt; &quot;6&quot;
-[8,9] --&gt; &quot;8-&gt;9&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [-1]
-<strong>Output:</strong> [&quot;-1&quot;]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0]
-<strong>Output:</strong> [&quot;0&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= nums.length &lt;= 20</code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-	<li>All the values of <code>nums</code> are <strong>unique</strong>.</li>
-	<li><code>nums</code> is sorted in ascending order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Similar Questions
-  1. [Missing Ranges](../missing-ranges) (Easy)
-  1. [Data Stream as Disjoint Intervals](../data-stream-as-disjoint-intervals) (Hard)
diff --git a/problems/summary-ranges/summary_ranges.go b/problems/summary-ranges/summary_ranges.go
deleted file mode 100644
index a7e282f3a..000000000
--- a/problems/summary-ranges/summary_ranges.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem228
diff --git a/problems/summary-ranges/summary_ranges_test.go b/problems/summary-ranges/summary_ranges_test.go
deleted file mode 100644
index a7e282f3a..000000000
--- a/problems/summary-ranges/summary_ranges_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem228
diff --git a/problems/super-egg-drop/README.md b/problems/super-egg-drop/README.md
deleted file mode 100644
index 092bac05e..000000000
--- a/problems/super-egg-drop/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../possible-bipartition "Possible Bipartition")
-　　　　　　　　　　　　　　　　
-[Next >](../fair-candy-swap "Fair Candy Swap")
-
-## [887. Super Egg Drop (Hard)](https://leetcode.com/problems/super-egg-drop "鸡蛋掉落")
-
-<p>You are given <code>k</code> identical eggs and you have access to a building with <code>n</code> floors labeled from <code>1</code> to <code>n</code>.</p>
-
-<p>You know that there exists a floor <code>f</code> where <code>0 &lt;= f &lt;= n</code> such that any egg dropped at a floor <strong>higher</strong> than <code>f</code> will <strong>break</strong>, and any egg dropped <strong>at or below</strong> floor <code>f</code> will <strong>not break</strong>.</p>
-
-<p>Each move, you may take an unbroken egg and drop it from any floor <code>x</code> (where <code>1 &lt;= x &lt;= n</code>). If the egg breaks, you can no longer use it. However, if the egg does not break, you may <strong>reuse</strong> it in future moves.</p>
-
-<p>Return <em>the <strong>minimum number of moves</strong> that you need to determine <strong>with certainty</strong> what the value of </em><code>f</code> is.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 1, n = 2
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>
-Drop the egg from floor 1. If it breaks, we know that f = 0.
-Otherwise, drop the egg from floor 2. If it breaks, we know that f = 1.
-If it does not break, then we know f = 2.
-Hence, we need at minimum 2 moves to determine with certainty what the value of f is.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 2, n = 6
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> k = 3, n = 14
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= 100</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/super-egg-drop/super_egg_drop.go b/problems/super-egg-drop/super_egg_drop.go
deleted file mode 100644
index 52535f5af..000000000
--- a/problems/super-egg-drop/super_egg_drop.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem887
diff --git a/problems/super-egg-drop/super_egg_drop_test.go b/problems/super-egg-drop/super_egg_drop_test.go
deleted file mode 100644
index 52535f5af..000000000
--- a/problems/super-egg-drop/super_egg_drop_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem887
diff --git a/problems/super-palindromes/README.md b/problems/super-palindromes/README.md
deleted file mode 100644
index 85d5a43b7..000000000
--- a/problems/super-palindromes/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-array-by-parity "Sort Array By Parity")
-　　　　　　　　　　　　　　　　
-[Next >](../sum-of-subarray-minimums "Sum of Subarray Minimums")
-
-## [906. Super Palindromes (Hard)](https://leetcode.com/problems/super-palindromes "超级回文数")
-
-<p>Let&#39;s say a positive integer is a <strong>super-palindrome</strong> if it is a palindrome, and it is also the square of a palindrome.</p>
-
-<p>Given two positive integers <code>left</code> and <code>right</code> represented as strings, return <em>the number of <strong>super-palindromes</strong> integers in the inclusive range</em> <code>[left, right]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = &quot;4&quot;, right = &quot;1000&quot;
-<strong>Output:</strong> 4
-<strong>Explanation</strong>: 4, 9, 121, and 484 are superpalindromes.
-Note that 676 is not a superpalindrome: 26 * 26 = 676, but 26 is not a palindrome.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> left = &quot;1&quot;, right = &quot;2&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= left.length, right.length &lt;= 18</code></li>
-	<li><code>left</code> and <code>right</code> consist of only digits.</li>
-	<li><code>left</code> and <code>right</code> cannot have leading zeros.</li>
-	<li><code>left</code> and <code>right</code> represent integers in the range <code>[1, 10<sup>18</sup> - 1]</code>.</li>
-	<li><code>left</code> is less than or equal to <code>right</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Enumeration](../../tag/enumeration/README.md)]
diff --git a/problems/super-palindromes/super_palindromes.go b/problems/super-palindromes/super_palindromes.go
deleted file mode 100644
index fbc9905ee..000000000
--- a/problems/super-palindromes/super_palindromes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem906
diff --git a/problems/super-palindromes/super_palindromes_test.go b/problems/super-palindromes/super_palindromes_test.go
deleted file mode 100644
index fbc9905ee..000000000
--- a/problems/super-palindromes/super_palindromes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem906
diff --git a/problems/super-pow/README.md b/problems/super-pow/README.md
deleted file mode 100644
index 084186323..000000000
--- a/problems/super-pow/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-two-integers "Sum of Two Integers")
-　　　　　　　　　　　　　　　　
-[Next >](../find-k-pairs-with-smallest-sums "Find K Pairs with Smallest Sums")
-
-## [372. Super Pow (Medium)](https://leetcode.com/problems/super-pow "超级次方")
-
-<p>Your task is to calculate <code>a<sup>b</sup></code> mod <code>1337</code> where <code>a</code> is a positive integer and <code>b</code> is an extremely large positive integer given in the form of an array.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> a = 2, b = [3]
-<strong>Output:</strong> 8
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> a = 2, b = [1,0]
-<strong>Output:</strong> 1024
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> a = 1, b = [4,3,3,8,5,2]
-<strong>Output:</strong> 1
-</pre><p><strong>Example 4:</strong></p>
-<pre><strong>Input:</strong> a = 2147483647, b = [2,0,0]
-<strong>Output:</strong> 1198
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= a &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>1 &lt;= b.length &lt;= 2000</code></li>
-	<li><code>0 &lt;= b[i] &lt;= 9</code></li>
-	<li><code>b</code> doesn&#39;t contain leading zeros.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-
-### Similar Questions
-  1. [Pow(x, n)](../powx-n) (Medium)
diff --git a/problems/super-pow/super_pow.go b/problems/super-pow/super_pow.go
deleted file mode 100644
index 95f01b264..000000000
--- a/problems/super-pow/super_pow.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem372
diff --git a/problems/super-pow/super_pow_test.go b/problems/super-pow/super_pow_test.go
deleted file mode 100644
index 95f01b264..000000000
--- a/problems/super-pow/super_pow_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem372
diff --git a/problems/super-ugly-number/README.md b/problems/super-ugly-number/README.md
deleted file mode 100644
index ab12d29e0..000000000
--- a/problems/super-ugly-number/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../burst-balloons "Burst Balloons")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-vertical-order-traversal "Binary Tree Vertical Order Traversal")
-
-## [313. Super Ugly Number (Medium)](https://leetcode.com/problems/super-ugly-number "超级丑数")
-
-<p>A <strong>super ugly number</strong> is a positive integer whose prime factors are in the array <code>primes</code>.</p>
-
-<p>Given an integer <code>n</code> and an array of integers <code>primes</code>, return <em>the</em> <code>n<sup>th</sup></code> <em><strong>super ugly number</strong></em>.</p>
-
-<p>The <code>n<sup>th</sup></code> <strong>super ugly number</strong> is <strong>guaranteed</strong> to fit in a <strong>32-bit</strong> signed integer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 12, primes = [2,7,13,19]
-<strong>Output:</strong> 32
-<strong>Explanation:</strong> [1,2,4,7,8,13,14,16,19,26,28,32] is the sequence of the first 12 super ugly numbers given primes = [2,7,13,19].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, primes = [2,3,5]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 1 has no prime factors, therefore all of its prime factors are in the array primes = [2,3,5].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>6</sup></code></li>
-	<li><code>1 &lt;= primes.length &lt;= 100</code></li>
-	<li><code>2 &lt;= primes[i] &lt;= 1000</code></li>
-	<li><code>primes[i]</code> is <strong>guaranteed</strong> to be a prime number.</li>
-	<li>All the values of <code>primes</code> are <strong>unique</strong> and sorted in <strong>ascending order</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Ugly Number II](../ugly-number-ii) (Medium)
diff --git a/problems/super-ugly-number/super_ugly_number.go b/problems/super-ugly-number/super_ugly_number.go
deleted file mode 100644
index a09fbb362..000000000
--- a/problems/super-ugly-number/super_ugly_number.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem313
diff --git a/problems/super-ugly-number/super_ugly_number_test.go b/problems/super-ugly-number/super_ugly_number_test.go
deleted file mode 100644
index a09fbb362..000000000
--- a/problems/super-ugly-number/super_ugly_number_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem313
diff --git a/problems/super-washing-machines/README.md b/problems/super-washing-machines/README.md
deleted file mode 100644
index 4fcb527d0..000000000
--- a/problems/super-washing-machines/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-palindromic-subsequence "Longest Palindromic Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../coin-change-2 "Coin Change 2")
-
-## [517. Super Washing Machines (Hard)](https://leetcode.com/problems/super-washing-machines "超级洗衣机")
-
-<p>You have <code>n</code> super washing machines on a line. Initially, each washing machine has some dresses or is empty.</p>
-
-<p>For each move, you could choose any <code>m</code> (<code>1 &lt;= m &lt;= n</code>) washing machines, and pass one dress of each washing machine to one of its adjacent washing machines at the same time.</p>
-
-<p>Given an integer array <code>machines</code> representing the number of dresses in each washing machine from left to right on the line, return <em>the minimum number of moves to make all the washing machines have the same number of dresses</em>. If it is not possible to do it, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> machines = [1,0,5]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-1st move:    1     0 &lt;-- 5    =&gt;    1     1     4
-2nd move:    1 &lt;-- 1 &lt;-- 4    =&gt;    2     1     3
-3rd move:    2     1 &lt;-- 3    =&gt;    2     2     2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> machines = [0,3,0]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-1st move:    0 &lt;-- 3     0    =&gt;    1     2     0
-2nd move:    1     2 --&gt; 0    =&gt;    1     1     1
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> machines = [0,2,0]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong>
-It&#39;s impossible to make all three washing machines have the same number of dresses.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == machines.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= machines[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
diff --git a/problems/super-washing-machines/super_washing_machines.go b/problems/super-washing-machines/super_washing_machines.go
deleted file mode 100644
index da8586f6e..000000000
--- a/problems/super-washing-machines/super_washing_machines.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem517
diff --git a/problems/super-washing-machines/super_washing_machines_test.go b/problems/super-washing-machines/super_washing_machines_test.go
deleted file mode 100644
index da8586f6e..000000000
--- a/problems/super-washing-machines/super_washing_machines_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem517
diff --git a/problems/surface-area-of-3d-shapes/README.md b/problems/surface-area-of-3d-shapes/README.md
deleted file mode 100644
index 26186f55f..000000000
--- a/problems/surface-area-of-3d-shapes/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-subsequence-widths "Sum of Subsequence Widths")
-　　　　　　　　　　　　　　　　
-[Next >](../groups-of-special-equivalent-strings "Groups of Special-Equivalent Strings")
-
-## [892. Surface Area of 3D Shapes (Easy)](https://leetcode.com/problems/surface-area-of-3d-shapes "三维形体的表面积")
-
-<p>You are given an <code>n x n</code> <code>grid</code> where you have placed some <code>1 x 1 x 1</code> cubes. Each value <code>v = grid[i][j]</code> represents a tower of <code>v</code> cubes placed on top of cell <code>(i, j)</code>.</p>
-
-<p>After placing these cubes, you have decided to glue any directly adjacent cubes to each other, forming several irregular 3D shapes.</p>
-
-<p>Return <em>the total surface area of the resulting shapes</em>.</p>
-
-<p><strong>Note:</strong> The bottom face of each shape counts toward its surface area.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/08/tmp-grid2.jpg" style="width: 162px; height: 162px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,2],[3,4]]
-<strong>Output:</strong> 34
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/08/tmp-grid4.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,1,1],[1,0,1],[1,1,1]]
-<strong>Output:</strong> 32
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/08/tmp-grid5.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> grid = [[2,2,2],[2,1,2],[2,2,2]]
-<strong>Output:</strong> 46
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length == grid[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 50</code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;= 50</code></li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/surface-area-of-3d-shapes/surface_area_of_3d_shapes.go b/problems/surface-area-of-3d-shapes/surface_area_of_3d_shapes.go
deleted file mode 100644
index b8cae0acf..000000000
--- a/problems/surface-area-of-3d-shapes/surface_area_of_3d_shapes.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem892
diff --git a/problems/surface-area-of-3d-shapes/surface_area_of_3d_shapes_test.go b/problems/surface-area-of-3d-shapes/surface_area_of_3d_shapes_test.go
deleted file mode 100644
index b8cae0acf..000000000
--- a/problems/surface-area-of-3d-shapes/surface_area_of_3d_shapes_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem892
diff --git a/problems/surrounded-regions/README.md b/problems/surrounded-regions/README.md
deleted file mode 100644
index ed9eb8e89..000000000
--- a/problems/surrounded-regions/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-root-to-leaf-numbers "Sum Root to Leaf Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-partitioning "Palindrome Partitioning")
-
-## [130. Surrounded Regions (Medium)](https://leetcode.com/problems/surrounded-regions "被围绕的区域")
-
-<p>Given an <code>m x n</code> matrix <code>board</code> containing <code>&#39;X&#39;</code> and <code>&#39;O&#39;</code>, <em>capture all regions that are 4-directionally&nbsp;surrounded by</em> <code>&#39;X&#39;</code>.</p>
-
-<p>A region is <strong>captured</strong> by flipping all <code>&#39;O&#39;</code>s into <code>&#39;X&#39;</code>s in that surrounded region.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/xogrid.jpg" style="width: 550px; height: 237px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;X&quot;,&quot;X&quot;,&quot;X&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;O&quot;,&quot;O&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;X&quot;,&quot;O&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;O&quot;,&quot;X&quot;,&quot;X&quot;]]
-<strong>Output:</strong> [[&quot;X&quot;,&quot;X&quot;,&quot;X&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;X&quot;,&quot;X&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;X&quot;,&quot;X&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;O&quot;,&quot;X&quot;,&quot;X&quot;]]
-<strong>Explanation:</strong> Surrounded regions should not be on the border, which means that any &#39;O&#39; on the border of the board are not flipped to &#39;X&#39;. Any &#39;O&#39; that is not on the border and it is not connected to an &#39;O&#39; on the border will be flipped to &#39;X&#39;. Two cells are connected if they are adjacent cells connected horizontally or vertically.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> board = [[&quot;X&quot;]]
-<strong>Output:</strong> [[&quot;X&quot;]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == board.length</code></li>
-	<li><code>n == board[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>board[i][j]</code> is <code>&#39;X&#39;</code> or <code>&#39;O&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Number of Islands](../number-of-islands) (Medium)
-  1. [Walls and Gates](../walls-and-gates) (Medium)
diff --git a/problems/surrounded-regions/surrounded_regions.go b/problems/surrounded-regions/surrounded_regions.go
deleted file mode 100644
index f6b247465..000000000
--- a/problems/surrounded-regions/surrounded_regions.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem130
diff --git a/problems/surrounded-regions/surrounded_regions_test.go b/problems/surrounded-regions/surrounded_regions_test.go
deleted file mode 100644
index f6b247465..000000000
--- a/problems/surrounded-regions/surrounded_regions_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem130
diff --git a/problems/suspicious-bank-accounts/README.md b/problems/suspicious-bank-accounts/README.md
deleted file mode 100644
index 10a9cba44..000000000
--- a/problems/suspicious-bank-accounts/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../next-palindrome-using-same-digits "Next Palindrome Using Same Digits")
-　　　　　　　　　　　　　　　　
-[Next >](../replace-all-digits-with-characters "Replace All Digits with Characters")
-
-## [1843. Suspicious Bank Accounts (Medium)](https://leetcode.com/problems/suspicious-bank-accounts "可疑银行账户")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/suspicious-bank-accounts/mysql_schemas.sql b/problems/suspicious-bank-accounts/mysql_schemas.sql
deleted file mode 100644
index d93ddcc38..000000000
--- a/problems/suspicious-bank-accounts/mysql_schemas.sql
+++ /dev/null
@@ -1,16 +0,0 @@
-Create table If Not Exists Accounts (account_id int, max_income int);
-Create table If Not Exists Transactions (transaction_id int, account_id int, type ENUM('creditor', 'debtor'), amount int, day datetime);
-Truncate table Accounts;
-insert into Accounts (account_id, max_income) values ('3', '21000');
-insert into Accounts (account_id, max_income) values ('4', '10400');
-Truncate table Transactions;
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('2', '3', 'Creditor', '107100', '2021-06-02 11:38:14');
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('4', '4', 'Creditor', '10400', '2021-06-20 12:39:18');
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('11', '4', 'Debtor', '58800', '2021-07-23 12:41:55');
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('1', '4', 'Creditor', '49300', '2021-05-03 16:11:04');
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('15', '3', 'Debtor', '75500', '2021-05-23 14:40:20');
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('10', '3', 'Creditor', '102100', '2021-06-15 10:37:16');
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('14', '4', 'Creditor', '56300', '2021-07-21 12:12:25');
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('19', '4', 'Debtor', '101100', '2021-05-09 15:21:49');
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('8', '3', 'Creditor', '64900', '2021-07-26 15:09:56');
-insert into Transactions (transaction_id, account_id, type, amount, day) values ('7', '3', 'Creditor', '90900', '2021-06-14 11:23:07');
diff --git a/problems/swap-adjacent-in-lr-string/README.md b/problems/swap-adjacent-in-lr-string/README.md
deleted file mode 100644
index ccc6e21f8..000000000
--- a/problems/swap-adjacent-in-lr-string/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../split-bst "Split BST")
-　　　　　　　　　　　　　　　　
-[Next >](../swim-in-rising-water "Swim in Rising Water")
-
-## [777. Swap Adjacent in LR String (Medium)](https://leetcode.com/problems/swap-adjacent-in-lr-string "在LR字符串中交换相邻字符")
-
-<p>In a string composed of <code>&#39;L&#39;</code>, <code>&#39;R&#39;</code>, and <code>&#39;X&#39;</code> characters, like <code>&quot;RXXLRXRXL&quot;</code>, a move consists of either replacing one occurrence of <code>&quot;XL&quot;</code> with <code>&quot;LX&quot;</code>, or replacing one occurrence of <code>&quot;RX&quot;</code> with <code>&quot;XR&quot;</code>. Given the starting string <code>start</code> and the ending string <code>end</code>, return <code>True</code> if and only if there exists a sequence of moves to transform one string to the other.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> start = &quot;RXXLRXRXL&quot;, end = &quot;XRLXXRRLX&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We can transform start to end following these steps:
-RXXLRXRXL -&gt;
-XRXLRXRXL -&gt;
-XRLXRXRXL -&gt;
-XRLXXRRXL -&gt;
-XRLXXRRLX
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> start = &quot;X&quot;, end = &quot;L&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= start.length&nbsp;&lt;= 10<sup>4</sup></code></li>
-	<li><code>start.length == end.length</code></li>
-	<li>Both <code>start</code> and <code>end</code> will only consist of characters in <code>&#39;L&#39;</code>, <code>&#39;R&#39;</code>, and&nbsp;<code>&#39;X&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think of the L and R's as people on a horizontal line, where X is a space.  The people can't cross each other, and also you can't go from XRX to RXX.
-</details>
diff --git a/problems/swap-adjacent-in-lr-string/swap_adjacent_in_lr_string.go b/problems/swap-adjacent-in-lr-string/swap_adjacent_in_lr_string.go
deleted file mode 100644
index c28119601..000000000
--- a/problems/swap-adjacent-in-lr-string/swap_adjacent_in_lr_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem777
diff --git a/problems/swap-adjacent-in-lr-string/swap_adjacent_in_lr_string_test.go b/problems/swap-adjacent-in-lr-string/swap_adjacent_in_lr_string_test.go
deleted file mode 100644
index c28119601..000000000
--- a/problems/swap-adjacent-in-lr-string/swap_adjacent_in_lr_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem777
diff --git a/problems/swap-for-longest-repeated-character-substring/README.md b/problems/swap-for-longest-repeated-character-substring/README.md
deleted file mode 100644
index d4f009b32..000000000
--- a/problems/swap-for-longest-repeated-character-substring/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-dice-rolls-with-target-sum "Number of Dice Rolls With Target Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../online-majority-element-in-subarray "Online Majority Element In Subarray")
-
-## [1156. Swap For Longest Repeated Character Substring (Medium)](https://leetcode.com/problems/swap-for-longest-repeated-character-substring "单字符重复子串的最大长度")
-
-<p>You are given a string <code>text</code>. You can swap two of the characters in the <code>text</code>.</p>
-
-<p>Return <em>the length of the longest substring with repeated characters</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;ababa&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We can swap the first &#39;b&#39; with the last &#39;a&#39;, or the last &#39;b&#39; with the first &#39;a&#39;. Then, the longest repeated character substring is &quot;aaa&quot; with length 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;aaabaaa&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> Swap &#39;b&#39; with the last &#39;a&#39; (or the first &#39;a&#39;), and we get longest repeated character substring &quot;aaaaaa&quot; with length 6.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> text = &quot;aaaaa&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> No need to swap, longest repeated character substring is &quot;aaaaa&quot; with length is 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= text.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>text</code> consist of lowercase English characters only.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Sliding Window](../../tag/sliding-window/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-There are two cases:  a block of characters, or two blocks of characters between one different character. 
- By keeping a run-length encoded version of the string, we can easily check these cases.
-</details>
diff --git a/problems/swap-nodes-in-pairs/README.md b/problems/swap-nodes-in-pairs/README.md
deleted file mode 100644
index 25b2d137f..000000000
--- a/problems/swap-nodes-in-pairs/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../merge-k-sorted-lists "Merge k Sorted Lists")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-nodes-in-k-group "Reverse Nodes in k-Group")
-
-## [24. Swap Nodes in Pairs (Medium)](https://leetcode.com/problems/swap-nodes-in-pairs "两两交换链表中的节点")
-
-<p>Given a&nbsp;linked list, swap every two adjacent nodes and return its head. You must solve the problem without&nbsp;modifying the values in the list&#39;s nodes (i.e., only nodes themselves may be changed.)</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/swap_ex1.jpg" style="width: 422px; height: 222px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4]
-<strong>Output:</strong> [2,1,4,3]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = []
-<strong>Output:</strong> []
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [1]
-<strong>Output:</strong> [1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the&nbsp;list&nbsp;is in the range <code>[0, 100]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-
-### Similar Questions
-  1. [Reverse Nodes in k-Group](../reverse-nodes-in-k-group) (Hard)
-  1. [Swapping Nodes in a Linked List](../swapping-nodes-in-a-linked-list) (Medium)
diff --git a/problems/swap-nodes-in-pairs/swap_nodes_in_pairs.go b/problems/swap-nodes-in-pairs/swap_nodes_in_pairs.go
deleted file mode 100644
index 3ffcff0ec..000000000
--- a/problems/swap-nodes-in-pairs/swap_nodes_in_pairs.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem24
diff --git a/problems/swap-nodes-in-pairs/swap_nodes_in_pairs_test.go b/problems/swap-nodes-in-pairs/swap_nodes_in_pairs_test.go
deleted file mode 100644
index 3ffcff0ec..000000000
--- a/problems/swap-nodes-in-pairs/swap_nodes_in_pairs_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem24
diff --git a/problems/swap-salary/README.md b/problems/swap-salary/README.md
deleted file mode 100644
index 3f9a113dc..000000000
--- a/problems/swap-salary/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../exchange-seats "Exchange Seats")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-product-of-three-numbers "Maximum Product of Three Numbers")
-
-## [627. Swap Salary (Easy)](https://leetcode.com/problems/swap-salary "变更性别")
-
-<p>Table: <code>Salary</code></p>
-
-<pre>
-+-------------+----------+
-| Column Name | Type     |
-+-------------+----------+
-| id          | int      |
-| name        | varchar  |
-| sex         | ENUM     |
-| salary      | int      |
-+-------------+----------+
-id is the primary key for this table.
-The sex column is ENUM value of type (&#39;m&#39;, &#39;f&#39;).
-The table contains information about an employee.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to swap all <code>&#39;f&#39;</code> and <code>&#39;m&#39;</code> values (i.e., change all <code>&#39;f&#39;</code> values to <code>&#39;m&#39;</code> and vice versa) with a <strong>single update statement</strong> and no intermediate temporary tables.</p>
-
-<p>Note that you must write a single update statement, <strong>do not</strong> write any select statement for this problem.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Salary table:
-+----+------+-----+--------+
-| id | name | sex | salary |
-+----+------+-----+--------+
-| 1  | A    | m   | 2500   |
-| 2  | B    | f   | 1500   |
-| 3  | C    | m   | 5500   |
-| 4  | D    | f   | 500    |
-+----+------+-----+--------+
-<strong>Output:</strong> 
-+----+------+-----+--------+
-| id | name | sex | salary |
-+----+------+-----+--------+
-| 1  | A    | f   | 2500   |
-| 2  | B    | m   | 1500   |
-| 3  | C    | f   | 5500   |
-| 4  | D    | m   | 500    |
-+----+------+-----+--------+
-<strong>Explanation:</strong> 
-(1, A) and (3, C) were changed from &#39;m&#39; to &#39;f&#39;.
-(2, B) and (4, D) were changed from &#39;f&#39; to &#39;m&#39;.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/swap-salary/mysql_schemas.sql b/problems/swap-salary/mysql_schemas.sql
deleted file mode 100644
index dd8dccfe3..000000000
--- a/problems/swap-salary/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Salary (id int, name varchar(100), sex char(1), salary int);
-Truncate table salary;
-insert into salary (id, name, sex, salary) values ('1', 'A', 'm', '2500');
-insert into salary (id, name, sex, salary) values ('2', 'B', 'f', '1500');
-insert into salary (id, name, sex, salary) values ('3', 'C', 'm', '5500');
-insert into salary (id, name, sex, salary) values ('4', 'D', 'f', '500');
diff --git a/problems/swap-salary/swap_salary.sql b/problems/swap-salary/swap_salary.sql
deleted file mode 100644
index 3225d0023..000000000
--- a/problems/swap-salary/swap_salary.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-# Write your MySQL query statement below
-
-# Method 1
-UPDATE salary
-SET sex = IF(sex = 'm', 'f', 'm');
-
-# Method 2
-UPDATE salary
-SET sex = CASE sex
-          WHEN 'm'
-            THEN 'f'
-          ELSE 'm' END;
diff --git a/problems/swapping-nodes-in-a-linked-list/README.md b/problems/swapping-nodes-in-a-linked-list/README.md
deleted file mode 100644
index 230f24024..000000000
--- a/problems/swapping-nodes-in-a-linked-list/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decode-xored-array "Decode XORed Array")
-　　　　　　　　　　　　　　　　
-[Next >](../minimize-hamming-distance-after-swap-operations "Minimize Hamming Distance After Swap Operations")
-
-## [1721. Swapping Nodes in a Linked List (Medium)](https://leetcode.com/problems/swapping-nodes-in-a-linked-list "交换链表中的节点")
-
-<p>You are given the <code>head</code> of a linked list, and an integer <code>k</code>.</p>
-
-<p>Return <em>the head of the linked list after <strong>swapping</strong> the values of the </em><code>k<sup>th</sup></code> <em>node from the beginning and the </em><code>k<sup>th</sup></code> <em>node from the end (the list is <strong>1-indexed</strong>).</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/linked1.jpg" style="width: 400px; height: 112px;" />
-<pre>
-<strong>Input:</strong> head = [1,2,3,4,5], k = 2
-<strong>Output:</strong> [1,4,3,2,5]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> head = [7,9,6,6,7,8,3,0,9,5], k = 5
-<strong>Output:</strong> [7,9,6,6,8,7,3,0,9,5]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the list is <code>n</code>.</li>
-	<li><code>1 &lt;= k &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Linked List](../../tag/linked-list/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-
-### Similar Questions
-  1. [Remove Nth Node From End of List](../remove-nth-node-from-end-of-list) (Medium)
-  1. [Swap Nodes in Pairs](../swap-nodes-in-pairs) (Medium)
-  1. [Reverse Nodes in k-Group](../reverse-nodes-in-k-group) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We can transform the linked list to an array this should ease things up
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After transforming the linked list to an array it becomes as easy as swapping two integers in an array then rebuilding the linked list
-</details>
diff --git a/problems/swim-in-rising-water/README.md b/problems/swim-in-rising-water/README.md
deleted file mode 100644
index b70685f53..000000000
--- a/problems/swim-in-rising-water/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../swap-adjacent-in-lr-string "Swap Adjacent in LR String")
-　　　　　　　　　　　　　　　　
-[Next >](../k-th-symbol-in-grammar "K-th Symbol in Grammar")
-
-## [778. Swim in Rising Water (Hard)](https://leetcode.com/problems/swim-in-rising-water "水位上升的泳池中游泳")
-
-<p>You are given an <code>n x n</code> integer matrix <code>grid</code> where each value <code>grid[i][j]</code> represents the elevation at that point <code>(i, j)</code>.</p>
-
-<p>The rain starts to fall. At time <code>t</code>, the depth of the water everywhere is <code>t</code>. You can swim from a square to another 4-directionally adjacent square if and only if the elevation of both squares individually are at most <code>t</code>. You can swim infinite distances in zero time. Of course, you must stay within the boundaries of the grid during your swim.</p>
-
-<p>Return <em>the least time until you can reach the bottom right square </em><code>(n - 1, n - 1)</code><em> if you start at the top left square </em><code>(0, 0)</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/swim1-grid.jpg" style="width: 164px; height: 165px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,2],[1,3]]
-<strong>Output:</strong> 3
-Explanation:
-At time 0, you are in grid location (0, 0).
-You cannot go anywhere else because 4-directionally adjacent neighbors have a higher elevation than t = 0.
-You cannot reach point (1, 1) until time 3.
-When the depth of water is 3, we can swim anywhere inside the grid.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/swim2-grid-1.jpg" style="width: 404px; height: 405px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1,2,3,4],[24,23,22,21,5],[12,13,14,15,16],[11,17,18,19,20],[10,9,8,7,6]]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> The final route is shown.
-We need to wait until time 16 so that (0, 0) and (4, 4) are connected.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= n &lt;= 50</code></li>
-	<li><code>0 &lt;= grid[i][j] &lt;&nbsp;n<sup>2</sup></code></li>
-	<li>Each value <code>grid[i][j]</code> is <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Path With Minimum Effort](../path-with-minimum-effort) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use either Dijkstra's, or binary search for the best time T for which you can reach the end if you only step on squares at most T.
-</details>
diff --git a/problems/swim-in-rising-water/swim_in_rising_water.go b/problems/swim-in-rising-water/swim_in_rising_water.go
deleted file mode 100644
index 5cc5d6429..000000000
--- a/problems/swim-in-rising-water/swim_in_rising_water.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem778
diff --git a/problems/swim-in-rising-water/swim_in_rising_water_test.go b/problems/swim-in-rising-water/swim_in_rising_water_test.go
deleted file mode 100644
index 5cc5d6429..000000000
--- a/problems/swim-in-rising-water/swim_in_rising_water_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem778
diff --git a/problems/symmetric-tree/README.md b/problems/symmetric-tree/README.md
deleted file mode 100644
index d5627165a..000000000
--- a/problems/symmetric-tree/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../same-tree "Same Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-tree-level-order-traversal "Binary Tree Level Order Traversal")
-
-## [101. Symmetric Tree (Easy)](https://leetcode.com/problems/symmetric-tree "对称二叉树")
-
-<p>Given the <code>root</code> of a binary tree, <em>check whether it is a mirror of itself</em> (i.e., symmetric around its center).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/symtree1.jpg" style="width: 354px; height: 291px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,2,3,4,4,3]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/symtree2.jpg" style="width: 308px; height: 258px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,2,null,3,null,3]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 1000]</code>.</li>
-	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you solve it both recursively and iteratively?
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/symmetric-tree/symmetric_tree.go b/problems/symmetric-tree/symmetric_tree.go
deleted file mode 100644
index 1b4995c61..000000000
--- a/problems/symmetric-tree/symmetric_tree.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem101
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func isSymmetric(root *TreeNode) bool {
-	return isMirror(root, root)
-}
-
-func isMirror(t1, t2 *TreeNode) bool {
-	if t1 == nil && t2 == nil {
-		return true
-	} else if t1 == nil || t2 == nil {
-		return false
-	}
-	return t1.Val == t2.Val && isMirror(t1.Left, t2.Right) && isMirror(t1.Right, t2.Left)
-}
diff --git a/problems/symmetric-tree/symmetric_tree_test.go b/problems/symmetric-tree/symmetric_tree_test.go
deleted file mode 100644
index f84c9d137..000000000
--- a/problems/symmetric-tree/symmetric_tree_test.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem101
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestIsSymmetric(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 2, 3, 4, 4, 3},
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 2, kit.NULL, 3, kit.NULL, 3},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isSymmetric(kit.SliceInt2TreeNode(tt.in))
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/synonymous-sentences/README.md b/problems/synonymous-sentences/README.md
deleted file mode 100644
index 011fc9ffe..000000000
--- a/problems/synonymous-sentences/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-common-region "Smallest Common Region")
-　　　　　　　　　　　　　　　　
-[Next >](../handshakes-that-dont-cross "Handshakes That Don't Cross")
-
-## [1258. Synonymous Sentences (Medium)](https://leetcode.com/problems/synonymous-sentences "近义词句子")
-
-Given a list of pairs of equivalent words&nbsp;<code>synonyms</code> and a sentence <code>text</code>,&nbsp;Return all possible synonymous sentences <strong>sorted lexicographically</strong>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:
-</strong>synonyms = [[&quot;happy&quot;,&quot;joy&quot;],[&quot;sad&quot;,&quot;sorrow&quot;],[&quot;joy&quot;,&quot;cheerful&quot;]],
-text = &quot;I am happy today but was sad yesterday&quot;
-<strong>Output:
-</strong>[&quot;I am cheerful today but was sad yesterday&quot;,
-​​​​​​​&quot;I am cheerful today but was sorrow yesterday&quot;,
-&quot;I am happy today but was sad yesterday&quot;,
-&quot;I am happy today but was sorrow yesterday&quot;,
-&quot;I am joy today but was sad yesterday&quot;,
-&quot;I am joy today but was sorrow yesterday&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;=&nbsp;synonyms.length &lt;= 10</code></li>
-	<li><code>synonyms[i].length == 2</code></li>
-	<li><code>synonyms[0] != synonyms[1]</code></li>
-	<li>All words consist of at most <code>10</code> English letters only.</li>
-	<li><code>text</code>&nbsp;is a single space separated sentence of at most <code>10</code> words.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find all synonymous groups of words.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use union-find data structure.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-By backtracking, generate all possible statements.
-</details>
diff --git a/problems/tag-validator/README.md b/problems/tag-validator/README.md
deleted file mode 100644
index f210a6fe3..000000000
--- a/problems/tag-validator/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../n-ary-tree-postorder-traversal "N-ary Tree Postorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../fraction-addition-and-subtraction "Fraction Addition and Subtraction")
-
-## [591. Tag Validator (Hard)](https://leetcode.com/problems/tag-validator "标签验证器")
-
-<p>Given a string representing a code snippet, implement a tag validator to parse the code and return whether it is valid.</p>
-
-<p>A code snippet is valid if all the following rules hold:</p>
-
-<ol>
-	<li>The code must be wrapped in a <b>valid closed tag</b>. Otherwise, the code is invalid.</li>
-	<li>A <b>closed tag</b> (not necessarily valid) has exactly the following format : <code>&lt;TAG_NAME&gt;TAG_CONTENT&lt;/TAG_NAME&gt;</code>. Among them, <code>&lt;TAG_NAME&gt;</code> is the start tag, and <code>&lt;/TAG_NAME&gt;</code> is the end tag. The TAG_NAME in start and end tags should be the same. A closed tag is <b>valid</b> if and only if the TAG_NAME and TAG_CONTENT are valid.</li>
-	<li>A <b>valid</b> <code>TAG_NAME</code> only contain <b>upper-case letters</b>, and has length in range [1,9]. Otherwise, the <code>TAG_NAME</code> is <b>invalid</b>.</li>
-	<li>A <b>valid</b> <code>TAG_CONTENT</code> may contain other <b>valid closed tags</b>, <b>cdata</b> and any characters (see note1) <b>EXCEPT</b> unmatched <code>&lt;</code>, unmatched start and end tag, and unmatched or closed tags with invalid TAG_NAME. Otherwise, the <code>TAG_CONTENT</code> is <b>invalid</b>.</li>
-	<li>A start tag is unmatched if no end tag exists with the same TAG_NAME, and vice versa. However, you also need to consider the issue of unbalanced when tags are nested.</li>
-	<li>A <code>&lt;</code> is unmatched if you cannot find a subsequent <code>&gt;</code>. And when you find a <code>&lt;</code> or <code>&lt;/</code>, all the subsequent characters until the next <code>&gt;</code> should be parsed as TAG_NAME (not necessarily valid).</li>
-	<li>The cdata has the following format : <code>&lt;![CDATA[CDATA_CONTENT]]&gt;</code>. The range of <code>CDATA_CONTENT</code> is defined as the characters between <code>&lt;![CDATA[</code> and the <b>first subsequent</b> <code>]]&gt;</code>.</li>
-	<li><code>CDATA_CONTENT</code> may contain <b>any characters</b>. The function of cdata is to forbid the validator to parse <code>CDATA_CONTENT</code>, so even it has some characters that can be parsed as tag (no matter valid or invalid), you should treat it as <b>regular characters</b>.</li>
-</ol>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> code = &quot;&lt;DIV&gt;This is the first line &lt;![CDATA[&lt;div&gt;]]&gt;&lt;/DIV&gt;&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 
-The code is wrapped in a closed tag : &lt;DIV&gt; and &lt;/DIV&gt;. 
-The TAG_NAME is valid, the TAG_CONTENT consists of some characters and cdata. 
-Although CDATA_CONTENT has an unmatched start tag with invalid TAG_NAME, it should be considered as plain text, not parsed as a tag.
-So TAG_CONTENT is valid, and then the code is valid. Thus return true.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> code = &quot;&lt;DIV&gt;&gt;&gt;  ![cdata[]] &lt;![CDATA[&lt;div&gt;]&gt;]]&gt;]]&gt;&gt;]&lt;/DIV&gt;&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-We first separate the code into : start_tag|tag_content|end_tag.
-start_tag -&gt; <b>&quot;&lt;DIV&gt;&quot;</b>
-end_tag -&gt; <b>&quot;&lt;/DIV&gt;&quot;</b>
-tag_content could also be separated into : text1|cdata|text2.
-text1 -&gt; <b>&quot;&gt;&gt;  ![cdata[]] &quot;</b>
-cdata -&gt; <b>&quot;&lt;![CDATA[&lt;div&gt;]&gt;]]&gt;&quot;</b>, where the CDATA_CONTENT is <b>&quot;&lt;div&gt;]&gt;&quot;</b>
-text2 -&gt; <b>&quot;]]&gt;&gt;]&quot;</b>
-The reason why start_tag is NOT <b>&quot;&lt;DIV&gt;&gt;&gt;&quot;</b> is because of the rule 6.
-The reason why cdata is NOT <b>&quot;&lt;![CDATA[&lt;div&gt;]&gt;]]&gt;]]&gt;&quot;</b> is because of the rule 7.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> code = &quot;&lt;A&gt;  &lt;B&gt; &lt;/A&gt;   &lt;/B&gt;&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Unbalanced. If &quot;&lt;A&gt;&quot; is closed, then &quot;&lt;B&gt;&quot; must be unmatched, and vice versa.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> code = &quot;&lt;DIV&gt;  div tag is not closed  &lt;DIV&gt;&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= code.length &lt;= 500</code></li>
-	<li><code>code</code> consists of English letters, digits, <code>&#39;&lt;&#39;</code>, <code>&#39;&gt;&#39;</code>, <code>&#39;/&#39;</code>, <code>&#39;!&#39;</code>, <code>&#39;[&#39;</code>, <code>&#39;]&#39;</code>, <code>&#39;.&#39;</code>, and <code>&#39; &#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Add Bold Tag in String](../add-bold-tag-in-string) (Medium)
diff --git a/problems/tag-validator/tag_validator.go b/problems/tag-validator/tag_validator.go
deleted file mode 100644
index 62b06cd23..000000000
--- a/problems/tag-validator/tag_validator.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem591
diff --git a/problems/tag-validator/tag_validator_test.go b/problems/tag-validator/tag_validator_test.go
deleted file mode 100644
index 62b06cd23..000000000
--- a/problems/tag-validator/tag_validator_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem591
diff --git a/problems/tallest-billboard/README.md b/problems/tallest-billboard/README.md
deleted file mode 100644
index 3d3e7c94a..000000000
--- a/problems/tallest-billboard/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../delete-columns-to-make-sorted-ii "Delete Columns to Make Sorted II")
-　　　　　　　　　　　　　　　　
-[Next >](../prison-cells-after-n-days "Prison Cells After N Days")
-
-## [956. Tallest Billboard (Hard)](https://leetcode.com/problems/tallest-billboard "最高的广告牌")
-
-<p>You are installing a billboard and want it to have the largest height. The billboard will have two steel supports, one on each side. Each steel support must be an equal height.</p>
-
-<p>You are given a collection of <code>rods</code> that can be welded together. For example, if you have rods of lengths <code>1</code>, <code>2</code>, and <code>3</code>, you can weld them together to make a support of length <code>6</code>.</p>
-
-<p>Return <em>the largest possible height of your billboard installation</em>. If you cannot support the billboard, return <code>0</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> rods = [1,2,3,6]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> We have two disjoint subsets {1,2,3} and {6}, which have the same sum = 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> rods = [1,2,3,4,5,6]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> We have two disjoint subsets {2,3,5} and {4,6}, which have the same sum = 10.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> rods = [1,2]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The billboard cannot be supported, so we return 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= rods.length &lt;= 20</code></li>
-	<li><code>1 &lt;= rods[i] &lt;= 1000</code></li>
-	<li><code>sum(rods[i]) &lt;= 5000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/tallest-billboard/tallest_billboard.go b/problems/tallest-billboard/tallest_billboard.go
deleted file mode 100644
index 450983657..000000000
--- a/problems/tallest-billboard/tallest_billboard.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem956
diff --git a/problems/tallest-billboard/tallest_billboard_test.go b/problems/tallest-billboard/tallest_billboard_test.go
deleted file mode 100644
index 450983657..000000000
--- a/problems/tallest-billboard/tallest_billboard_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem956
diff --git a/problems/target-sum/README.md b/problems/target-sum/README.md
deleted file mode 100644
index e1998bc26..000000000
--- a/problems/target-sum/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../reverse-pairs "Reverse Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../teemo-attacking "Teemo Attacking")
-
-## [494. Target Sum (Medium)](https://leetcode.com/problems/target-sum "目标和")
-
-<p>You are given an integer array <code>nums</code> and an integer <code>target</code>.</p>
-
-<p>You want to build an <strong>expression</strong> out of nums by adding one of the symbols <code>&#39;+&#39;</code> and <code>&#39;-&#39;</code> before each integer in nums and then concatenate all the integers.</p>
-
-<ul>
-	<li>For example, if <code>nums = [2, 1]</code>, you can add a <code>&#39;+&#39;</code> before <code>2</code> and a <code>&#39;-&#39;</code> before <code>1</code> and concatenate them to build the expression <code>&quot;+2-1&quot;</code>.</li>
-</ul>
-
-<p>Return the number of different <strong>expressions</strong> that you can build, which evaluates to <code>target</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1,1,1], target = 3
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> There are 5 ways to assign symbols to make the sum of nums be target 3.
--1 + 1 + 1 + 1 + 1 = 3
-+1 - 1 + 1 + 1 + 1 = 3
-+1 + 1 - 1 + 1 + 1 = 3
-+1 + 1 + 1 - 1 + 1 = 3
-+1 + 1 + 1 + 1 - 1 = 3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1], target = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 20</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
-	<li><code>0 &lt;= sum(nums[i]) &lt;= 1000</code></li>
-	<li><code>-1000 &lt;= target &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Expression Add Operators](../expression-add-operators) (Hard)
diff --git a/problems/target-sum/target_sum.go b/problems/target-sum/target_sum.go
deleted file mode 100644
index 2807acc5b..000000000
--- a/problems/target-sum/target_sum.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem494
diff --git a/problems/target-sum/target_sum_test.go b/problems/target-sum/target_sum_test.go
deleted file mode 100644
index 2807acc5b..000000000
--- a/problems/target-sum/target_sum_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem494
diff --git a/problems/task-scheduler/README.md b/problems/task-scheduler/README.md
deleted file mode 100644
index 1b9a40e12..000000000
--- a/problems/task-scheduler/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../not-boring-movies "Not Boring Movies")
-　　　　　　　　　　　　　　　　
-[Next >](../design-circular-queue "Design Circular Queue")
-
-## [621. Task Scheduler (Medium)](https://leetcode.com/problems/task-scheduler "任务调度器")
-
-<p>Given a characters array <code>tasks</code>, representing the tasks a CPU needs to do, where each letter represents a different task. Tasks could be done in any order. Each task is done in one unit of time. For each unit of time, the CPU could complete either one task or just be idle.</p>
-
-<p>However, there is a non-negative integer&nbsp;<code>n</code> that represents the cooldown period between&nbsp;two <b>same tasks</b>&nbsp;(the same letter in the array), that is that there must be at least <code>n</code> units of time between any two same tasks.</p>
-
-<p>Return <em>the least number of units of times that the CPU will take to finish all the given tasks</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [&quot;A&quot;,&quot;A&quot;,&quot;A&quot;,&quot;B&quot;,&quot;B&quot;,&quot;B&quot;], n = 2
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> 
-A -&gt; B -&gt; idle -&gt; A -&gt; B -&gt; idle -&gt; A -&gt; B
-There is at least 2 units of time between any two same tasks.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [&quot;A&quot;,&quot;A&quot;,&quot;A&quot;,&quot;B&quot;,&quot;B&quot;,&quot;B&quot;], n = 0
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> On this case any permutation of size 6 would work since n = 0.
-[&quot;A&quot;,&quot;A&quot;,&quot;A&quot;,&quot;B&quot;,&quot;B&quot;,&quot;B&quot;]
-[&quot;A&quot;,&quot;B&quot;,&quot;A&quot;,&quot;B&quot;,&quot;A&quot;,&quot;B&quot;]
-[&quot;B&quot;,&quot;B&quot;,&quot;B&quot;,&quot;A&quot;,&quot;A&quot;,&quot;A&quot;]
-...
-And so on.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> tasks = [&quot;A&quot;,&quot;A&quot;,&quot;A&quot;,&quot;A&quot;,&quot;A&quot;,&quot;A&quot;,&quot;B&quot;,&quot;C&quot;,&quot;D&quot;,&quot;E&quot;,&quot;F&quot;,&quot;G&quot;], n = 2
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> 
-One possible solution is
-A -&gt; B -&gt; C -&gt; A -&gt; D -&gt; E -&gt; A -&gt; F -&gt; G -&gt; A -&gt; idle -&gt; idle -&gt; A -&gt; idle -&gt; idle -&gt; A
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= task.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>tasks[i]</code> is upper-case English letter.</li>
-	<li>The integer <code>n</code> is in the range <code>[0, 100]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-
-### Similar Questions
-  1. [Rearrange String k Distance Apart](../rearrange-string-k-distance-apart) (Hard)
-  1. [Reorganize String](../reorganize-string) (Medium)
-  1. [Maximum Number of Weeks for Which You Can Work](../maximum-number-of-weeks-for-which-you-can-work) (Medium)
diff --git a/problems/task-scheduler/task_scheduler.go b/problems/task-scheduler/task_scheduler.go
deleted file mode 100644
index e66f99980..000000000
--- a/problems/task-scheduler/task_scheduler.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem621
diff --git a/problems/task-scheduler/task_scheduler_test.go b/problems/task-scheduler/task_scheduler_test.go
deleted file mode 100644
index e66f99980..000000000
--- a/problems/task-scheduler/task_scheduler_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem621
diff --git a/problems/team-scores-in-football-tournament/README.md b/problems/team-scores-in-football-tournament/README.md
deleted file mode 100644
index ea77aa03e..000000000
--- a/problems/team-scores-in-football-tournament/README.md
+++ /dev/null
@@ -1,93 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../queries-quality-and-percentage "Queries Quality and Percentage")
-　　　　　　　　　　　　　　　　
-[Next >](../intersection-of-three-sorted-arrays "Intersection of Three Sorted Arrays")
-
-## [1212. Team Scores in Football Tournament (Medium)](https://leetcode.com/problems/team-scores-in-football-tournament "查询球队积分")
-
-<p>Table: <code>Teams</code></p>
-
-<pre>
-+---------------+----------+
-| Column Name   | Type     |
-+---------------+----------+
-| team_id       | int      |
-| team_name     | varchar  |
-+---------------+----------+
-team_id is the primary key of this table.
-Each row of this table represents a single football team.
-</pre>
-
-<p>Table:&nbsp;<code>Matches</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| match_id      | int     |
-| host_team     | int     |
-| guest_team    | int     | 
-| host_goals    | int     |
-| guest_goals   | int     |
-+---------------+---------+
-match_id is the primary key of this table.
-Each row is a record of a finished match between two different teams. 
-Teams host_team and guest_team are represented by their IDs in the teams table (team_id) and they scored host_goals and guest_goals goals respectively.
-</pre>
-
-<p>&nbsp;</p>
-You would like to compute the scores of all teams after all matches. Points are awarded as follows:
-
-<ul>
-	<li>A team&nbsp;receives three points if they win&nbsp;a match (Score strictly more goals than the opponent team).</li>
-	<li>A team&nbsp;receives one point if they draw a match (Same number of goals as the opponent team).</li>
-	<li>A team&nbsp;receives no points if they lose a match (Score less goals than the opponent team).</li>
-</ul>
-
-<p>Write an SQL query that selects the <strong>team_id</strong>, <strong>team_name</strong> and <strong>num_points</strong> of each team in the tournament after all described matches. Result table should be ordered by <strong>num_points</strong> (decreasing order). In case of a tie, order the records by <strong>team_id</strong> (increasing order).</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-<code>Teams </code>table:
-+-----------+--------------+
-| team_id   | team_name    |
-+-----------+--------------+
-| 10        | Leetcode FC  |
-| 20        | NewYork FC   |
-| 30        | Atlanta FC   |
-| 40        | Chicago FC   |
-| 50        | Toronto FC   |
-+-----------+--------------+
-
-<code>Matches </code>table:
-+------------+--------------+---------------+-------------+--------------+
-| match_id   | host_team    | guest_team    | host_goals  | guest_goals  |
-+------------+--------------+---------------+-------------+--------------+
-| 1          | 10           | 20            | 3           | 0            |
-| 2          | 30           | 10            | 2           | 2            |
-| 3          | 10           | 50            | 5           | 1            |
-| 4          | 20           | 30            | 1           | 0            |
-| 5          | 50           | 30            | 1           | 0            |
-+------------+--------------+---------------+-------------+--------------+
-
-Result table:
-+------------+--------------+---------------+
-| team_id    | team_name    | num_points    |
-+------------+--------------+---------------+
-| 10         | Leetcode FC  | 7             |
-| 20         | NewYork FC   | 3             |
-| 50         | Toronto FC   | 3             |
-| 30         | Atlanta FC   | 1             |
-| 40         | Chicago FC   | 0             |
-+------------+--------------+---------------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/team-scores-in-football-tournament/mysql_schemas.sql b/problems/team-scores-in-football-tournament/mysql_schemas.sql
deleted file mode 100644
index a09fa129d..000000000
--- a/problems/team-scores-in-football-tournament/mysql_schemas.sql
+++ /dev/null
@@ -1,14 +0,0 @@
-Create table If Not Exists Teams (team_id int, team_name varchar(30));
-Create table If Not Exists Matches (match_id int, host_team int, guest_team int, host_goals int, guest_goals int);
-Truncate table Teams;
-insert into Teams (team_id, team_name) values ('10', 'Leetcode FC');
-insert into Teams (team_id, team_name) values ('20', 'NewYork FC');
-insert into Teams (team_id, team_name) values ('30', 'Atlanta FC');
-insert into Teams (team_id, team_name) values ('40', 'Chicago FC');
-insert into Teams (team_id, team_name) values ('50', 'Toronto FC');
-Truncate table Matches;
-insert into Matches (match_id, host_team, guest_team, host_goals, guest_goals) values ('1', '10', '20', '3', '0');
-insert into Matches (match_id, host_team, guest_team, host_goals, guest_goals) values ('2', '30', '10', '2', '2');
-insert into Matches (match_id, host_team, guest_team, host_goals, guest_goals) values ('3', '10', '50', '5', '1');
-insert into Matches (match_id, host_team, guest_team, host_goals, guest_goals) values ('4', '20', '30', '1', '0');
-insert into Matches (match_id, host_team, guest_team, host_goals, guest_goals) values ('5', '50', '30', '1', '0');
diff --git a/problems/teemo-attacking/README.md b/problems/teemo-attacking/README.md
deleted file mode 100644
index 2698808e4..000000000
--- a/problems/teemo-attacking/README.md
+++ /dev/null
@@ -1,58 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../target-sum "Target Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../next-greater-element-i "Next Greater Element I")
-
-## [495. Teemo Attacking (Easy)](https://leetcode.com/problems/teemo-attacking "提莫攻击")
-
-<p>Our hero Teemo is attacking an enemy Ashe with poison attacks! When Teemo attacks Ashe, Ashe gets poisoned for a exactly <code>duration</code> seconds. More formally, an attack at second <code>t</code> will mean Ashe is poisoned during the <strong>inclusive</strong> time interval <code>[t, t + duration - 1]</code>. If Teemo attacks again <strong>before</strong> the poison effect ends, the timer for it is <strong>reset</strong>, and the poison effect will end <code>duration</code> seconds after the new attack.</p>
-
-<p>You are given a <strong>non-decreasing</strong> integer array <code>timeSeries</code>, where <code>timeSeries[i]</code> denotes that Teemo attacks Ashe at second <code>timeSeries[i]</code>, and an integer <code>duration</code>.</p>
-
-<p>Return <em>the <strong>total</strong> number of seconds that Ashe is poisoned</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> timeSeries = [1,4], duration = 2
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> Teemo&#39;s attacks on Ashe go as follows:
-- At second 1, Teemo attacks, and Ashe is poisoned for seconds 1 and 2.
-- At second 4, Teemo attacks, and Ashe is poisoned for seconds 4 and 5.
-Ashe is poisoned for seconds 1, 2, 4, and 5, which is 4 seconds in total.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> timeSeries = [1,2], duration = 2
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Teemo&#39;s attacks on Ashe go as follows:
-- At second 1, Teemo attacks, and Ashe is poisoned for seconds 1 and 2.
-- At second 2 however, Teemo attacks again and resets the poison timer. Ashe is poisoned for seconds 2 and 3.
-Ashe is poisoned for seconds 1, 2, and 3, which is 3 seconds in total.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= timeSeries.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= timeSeries[i], duration &lt;= 10<sup>7</sup></code></li>
-	<li><code>timeSeries</code> is sorted in <strong>non-decreasing</strong> order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Similar Questions
-  1. [Merge Intervals](../merge-intervals) (Medium)
-  1. [Can Place Flowers](../can-place-flowers) (Easy)
-  1. [Dota2 Senate](../dota2-senate) (Medium)
diff --git a/problems/teemo-attacking/teemo_attacking.go b/problems/teemo-attacking/teemo_attacking.go
deleted file mode 100644
index 8f145b0c1..000000000
--- a/problems/teemo-attacking/teemo_attacking.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem495
diff --git a/problems/teemo-attacking/teemo_attacking_test.go b/problems/teemo-attacking/teemo_attacking_test.go
deleted file mode 100644
index 8f145b0c1..000000000
--- a/problems/teemo-attacking/teemo_attacking_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem495
diff --git a/problems/tenth-line/README.md b/problems/tenth-line/README.md
deleted file mode 100644
index 83cca284d..000000000
--- a/problems/tenth-line/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../transpose-file "Transpose File")
-　　　　　　　　　　　　　　　　
-[Next >](../delete-duplicate-emails "Delete Duplicate Emails")
-
-## [195. Tenth Line (Easy)](https://leetcode.com/problems/tenth-line "第十行")
-
-<p>Given a text file&nbsp;<code>file.txt</code>, print&nbsp;just the 10th line of the&nbsp;file.</p>
-
-<p><strong>Example:</strong></p>
-
-<p>Assume that <code>file.txt</code> has the following content:</p>
-
-<pre>
-Line 1
-Line 2
-Line 3
-Line 4
-Line 5
-Line 6
-Line 7
-Line 8
-Line 9
-Line 10
-</pre>
-
-<p>Your script should output the tenth line, which is:</p>
-
-<pre>
-Line 10
-</pre>
-
-<div class="spoilers"><b>Note:</b><br />
-1. If the file contains less than 10 lines, what should you output?<br />
-2. There&#39;s at least three different solutions. Try to explore all possibilities.</div>
-
-### Related Topics
-  [[Shell](../../tag/shell/README.md)]
diff --git a/problems/tenth-line/file.txt b/problems/tenth-line/file.txt
deleted file mode 100644
index 00935f183..000000000
--- a/problems/tenth-line/file.txt
+++ /dev/null
@@ -1,10 +0,0 @@
-Line 1
-Line 2
-Line 3
-Line 4
-Line 5
-Line 6
-Line 7
-Line 8
-Line 9
-Line 10
diff --git a/problems/tenth-line/tenth_line.bash b/problems/tenth-line/tenth_line.bash
deleted file mode 100755
index b8ddf9abb..000000000
--- a/problems/tenth-line/tenth_line.bash
+++ /dev/null
@@ -1,5 +0,0 @@
-#!/usr/bin/env bash
-
-# Read from the file file.txt and output the tenth line to stdout.
-
-sed -n '10p' file.txt
diff --git a/problems/ternary-expression-parser/README.md b/problems/ternary-expression-parser/README.md
deleted file mode 100644
index 9ada653a3..000000000
--- a/problems/ternary-expression-parser/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-all-anagrams-in-a-string "Find All Anagrams in a String")
-　　　　　　　　　　　　　　　　
-[Next >](../k-th-smallest-in-lexicographical-order "K-th Smallest in Lexicographical Order")
-
-## [439. Ternary Expression Parser (Medium)](https://leetcode.com/problems/ternary-expression-parser "三元表达式解析器")
-
-<p>Given a string representing arbitrarily nested ternary expressions, calculate the result of the expression. You can always assume that the given expression is valid and only consists of digits <code>0-9</code>, <code>?</code>, <code>:</code>, <code>T</code> and <code>F</code> (<code>T</code> and <code>F</code> represent True and False respectively).
-
-<p><b>Note:</b>
-<ol>
-<li>The length of the given string is &le; 10000.</li>
-<li>Each number will contain only one digit.</li>
-<li>The conditional expressions group right-to-left (as usual in most languages).</li>
-<li>The condition will always be either <code>T</code> or <code>F</code>. That is, the condition will never be a digit.</li>
-<li>The result of the expression will always evaluate to either a digit <code>0-9</code>, <code>T</code> or <code>F</code>.</li>
-</ol>
-</p>
-
-<p>
-<b>Example 1:</b>
-<pre>
-<b>Input:</b> "T?2:3"
-
-<b>Output:</b> "2"
-
-<b>Explanation:</b> If true, then result is 2; otherwise result is 3.
-</pre>
-</p>
-
-<p>
-<b>Example 2:</b>
-<pre>
-<b>Input:</b> "F?1:T?4:5"
-
-<b>Output:</b> "4"
-
-<b>Explanation:</b> The conditional expressions group right-to-left. Using parenthesis, it is read/evaluated as:
-
-             "(F ? 1 : (T ? 4 : 5))"                   "(F ? 1 : (T ? 4 : 5))"
-          -> "(F ? 1 : 4)"                 or       -> "(T ? 4 : 5)"
-          -> "4"                                    -> "4"
-</pre>
-</p>
-
-<p>
-<b>Example 3:</b>
-<pre>
-<b>Input:</b> "T?T?F:5:3"
-
-<b>Output:</b> "F"
-
-<b>Explanation:</b> The conditional expressions group right-to-left. Using parenthesis, it is read/evaluated as:
-
-             "(T ? (T ? F : 5) : 3)"                   "(T ? (T ? F : 5) : 3)"
-          -> "(T ? F : 3)"                 or       -> "(T ? F : 5)"
-          -> "F"                                    -> "F"
-</pre>
-</p>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-
-### Similar Questions
-  1. [Mini Parser](../mini-parser) (Medium)
-  1. [Remove Comments](../remove-comments) (Medium)
-  1. [Parse Lisp Expression](../parse-lisp-expression) (Hard)
diff --git a/problems/ternary-expression-parser/ternary_expression_parser.go b/problems/ternary-expression-parser/ternary_expression_parser.go
deleted file mode 100644
index 7318f9580..000000000
--- a/problems/ternary-expression-parser/ternary_expression_parser.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem439
diff --git a/problems/ternary-expression-parser/ternary_expression_parser_test.go b/problems/ternary-expression-parser/ternary_expression_parser_test.go
deleted file mode 100644
index 7318f9580..000000000
--- a/problems/ternary-expression-parser/ternary_expression_parser_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem439
diff --git a/problems/text-justification/README.md b/problems/text-justification/README.md
deleted file mode 100644
index be21671e2..000000000
--- a/problems/text-justification/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../add-binary "Add Binary")
-　　　　　　　　　　　　　　　　
-[Next >](../sqrtx "Sqrt(x)")
-
-## [68. Text Justification (Hard)](https://leetcode.com/problems/text-justification "文本左右对齐")
-
-<p>Given an array of strings <code>words</code> and a width <code>maxWidth</code>, format the text such that each line has exactly <code>maxWidth</code> characters and is fully (left and right) justified.</p>
-
-<p>You should pack your words in a greedy approach; that is, pack as many words as you can in each line. Pad extra spaces <code>&#39; &#39;</code> when necessary so that each line has exactly <code>maxWidth</code> characters.</p>
-
-<p>Extra spaces between words should be distributed as evenly as possible. If the number of spaces on a line does not divide evenly between words, the empty slots on the left will be assigned more spaces than the slots on the right.</p>
-
-<p>For the last line of text, it should be left-justified and no extra space is inserted between words.</p>
-
-<p><strong>Note:</strong></p>
-
-<ul>
-	<li>A word is defined as a character sequence consisting of non-space characters only.</li>
-	<li>Each word&#39;s length is guaranteed to be greater than 0 and not exceed maxWidth.</li>
-	<li>The input array <code>words</code> contains at least one word.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;This&quot;, &quot;is&quot;, &quot;an&quot;, &quot;example&quot;, &quot;of&quot;, &quot;text&quot;, &quot;justification.&quot;], maxWidth = 16
-<strong>Output:</strong>
-[
-&nbsp; &nbsp;&quot;This &nbsp; &nbsp;is &nbsp; &nbsp;an&quot;,
-&nbsp; &nbsp;&quot;example &nbsp;of text&quot;,
-&nbsp; &nbsp;&quot;justification. &nbsp;&quot;
-]</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;What&quot;,&quot;must&quot;,&quot;be&quot;,&quot;acknowledgment&quot;,&quot;shall&quot;,&quot;be&quot;], maxWidth = 16
-<strong>Output:</strong>
-[
-&nbsp; &quot;What &nbsp; must &nbsp; be&quot;,
-&nbsp; &quot;acknowledgment &nbsp;&quot;,
-&nbsp; &quot;shall be &nbsp; &nbsp; &nbsp; &nbsp;&quot;
-]
-<strong>Explanation:</strong> Note that the last line is &quot;shall be    &quot; instead of &quot;shall     be&quot;, because the last line must be left-justified instead of fully-justified.
-Note that the second line is also left-justified becase it contains only one word.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;Science&quot;,&quot;is&quot;,&quot;what&quot;,&quot;we&quot;,&quot;understand&quot;,&quot;well&quot;,&quot;enough&quot;,&quot;to&quot;,&quot;explain&quot;,&quot;to&quot;,&quot;a&quot;,&quot;computer.&quot;,&quot;Art&quot;,&quot;is&quot;,&quot;everything&quot;,&quot;else&quot;,&quot;we&quot;,&quot;do&quot;], maxWidth = 20
-<strong>Output:</strong>
-[
-&nbsp; &quot;Science &nbsp;is &nbsp;what we&quot;,
-  &quot;understand &nbsp; &nbsp; &nbsp;well&quot;,
-&nbsp; &quot;enough to explain to&quot;,
-&nbsp; &quot;a &nbsp;computer. &nbsp;Art is&quot;,
-&nbsp; &quot;everything &nbsp;else &nbsp;we&quot;,
-&nbsp; &quot;do &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&quot;
-]</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 300</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 20</code></li>
-	<li><code>words[i]</code> consists of only English letters and symbols.</li>
-	<li><code>1 &lt;= maxWidth &lt;= 100</code></li>
-	<li><code>words[i].length &lt;= maxWidth</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/text-justification/text_justification.go b/problems/text-justification/text_justification.go
deleted file mode 100644
index bb720d604..000000000
--- a/problems/text-justification/text_justification.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem68
diff --git a/problems/text-justification/text_justification_test.go b/problems/text-justification/text_justification_test.go
deleted file mode 100644
index bb720d604..000000000
--- a/problems/text-justification/text_justification_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem68
diff --git a/problems/the-airport-with-the-most-traffic/README.md b/problems/the-airport-with-the-most-traffic/README.md
deleted file mode 100644
index 00c570b75..000000000
--- a/problems/the-airport-with-the-most-traffic/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-operations-to-make-the-array-k-increasing "Minimum Operations to Make the Array K-Increasing")
-　　　　　　　　　　　　　　　　
-[Next >](../elements-in-array-after-removing-and-replacing-elements "Elements in Array After Removing and Replacing Elements")
-
-## [2112. The Airport With the Most Traffic (Medium)](https://leetcode.com/problems/the-airport-with-the-most-traffic "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/the-airport-with-the-most-traffic/mysql_schemas.sql b/problems/the-airport-with-the-most-traffic/mysql_schemas.sql
deleted file mode 100644
index 2c4c276f3..000000000
--- a/problems/the-airport-with-the-most-traffic/mysql_schemas.sql
+++ /dev/null
@@ -1,5 +0,0 @@
-Create table If Not Exists Flights (departure_airport int, arrival_airport int, flights_count int);
-Truncate table Flights;
-insert into Flights (departure_airport, arrival_airport, flights_count) values ('1', '2', '4');
-insert into Flights (departure_airport, arrival_airport, flights_count) values ('2', '1', '5');
-insert into Flights (departure_airport, arrival_airport, flights_count) values ('2', '4', '5');
diff --git a/problems/the-category-of-each-member-in-the-store/README.md b/problems/the-category-of-each-member-in-the-store/README.md
deleted file mode 100644
index 2f2569f3c..000000000
--- a/problems/the-category-of-each-member-in-the-store/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../parallel-courses-iii "Parallel Courses III")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-separate-sentence-into-rows "Minimum Cost to Separate Sentence Into Rows")
-
-## [2051. The Category of Each Member in the Store (Medium)](https://leetcode.com/problems/the-category-of-each-member-in-the-store "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/the-category-of-each-member-in-the-store/mysql_schemas.sql b/problems/the-category-of-each-member-in-the-store/mysql_schemas.sql
deleted file mode 100644
index e5664f6fc..000000000
--- a/problems/the-category-of-each-member-in-the-store/mysql_schemas.sql
+++ /dev/null
@@ -1,21 +0,0 @@
-Create table If Not Exists Members (member_id int, name varchar(30));
-Create table If Not Exists Visits (visit_id int, member_id int, visit_date date);
-Create table If Not Exists Purchases (visit_id int, charged_amount int);
-Truncate table Members;
-insert into Members (member_id, name) values ('9', 'Alice');
-insert into Members (member_id, name) values ('11', 'Bob');
-insert into Members (member_id, name) values ('3', 'Winston');
-insert into Members (member_id, name) values ('8', 'Hercy');
-insert into Members (member_id, name) values ('1', 'Narihan');
-Truncate table Visits;
-insert into Visits (visit_id, member_id, visit_date) values ('22', '11', '2021-10-28');
-insert into Visits (visit_id, member_id, visit_date) values ('16', '11', '2021-01-12');
-insert into Visits (visit_id, member_id, visit_date) values ('18', '9', '2021-12-10');
-insert into Visits (visit_id, member_id, visit_date) values ('19', '3', '2021-10-19');
-insert into Visits (visit_id, member_id, visit_date) values ('12', '11', '2021-03-01');
-insert into Visits (visit_id, member_id, visit_date) values ('17', '8', '2021-05-07');
-insert into Visits (visit_id, member_id, visit_date) values ('21', '9', '2021-05-12');
-Truncate table Purchases;
-insert into Purchases (visit_id, charged_amount) values ('12', '2000');
-insert into Purchases (visit_id, charged_amount) values ('18', '9000');
-insert into Purchases (visit_id, charged_amount) values ('17', '7000');
diff --git a/problems/the-dining-philosophers/README.md b/problems/the-dining-philosophers/README.md
deleted file mode 100644
index 8199b4c4e..000000000
--- a/problems/the-dining-philosophers/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../report-contiguous-dates "Report Contiguous Dates")
-　　　　　　　　　　　　　　　　
-[Next >](../airplane-seat-assignment-probability "Airplane Seat Assignment Probability")
-
-## [1226. The Dining Philosophers (Medium)](https://leetcode.com/problems/the-dining-philosophers "哲学家进餐")
-
-<p>Five silent philosophers&nbsp;sit at a round table with bowls of spaghetti. Forks are placed between each pair of adjacent philosophers.</p>
-
-<p>Each philosopher must alternately think and eat. However, a philosopher can only eat spaghetti when they have both left and right forks. Each fork can be held by only one philosopher and so a philosopher can use the fork only if it is not being used by another philosopher. After an individual philosopher finishes eating, they need to put down both forks so that the forks become available to others. A philosopher can take the fork on their right or the one on their left as they become available, but cannot start eating before getting both forks.</p>
-
-<p>Eating is not limited by the remaining amounts of spaghetti or stomach space; an infinite supply and an infinite demand are assumed.</p>
-
-<p>Design a discipline of behaviour (a concurrent algorithm) such that no philosopher will starve;&nbsp;<i>i.e.</i>, each can forever continue to alternate between eating and thinking, assuming that no philosopher can know when others may want to eat or think.</p>
-
-<p style="text-align: center"><img alt="" src="https://assets.leetcode.com/uploads/2019/09/24/an_illustration_of_the_dining_philosophers_problem.png" style="width: 400px; height: 415px;" /></p>
-
-<p style="text-align: center"><em>The problem statement and the image above are taken from <a href="https://en.wikipedia.org/wiki/Dining_philosophers_problem" target="_blank">wikipedia.org</a></em></p>
-
-<p>&nbsp;</p>
-
-<p>The philosophers&#39; ids are numbered from <strong>0</strong> to <strong>4</strong> in a <strong>clockwise</strong> order. Implement the function&nbsp;<code>void wantsToEat(philosopher, pickLeftFork, pickRightFork, eat, putLeftFork, putRightFork)</code> where:</p>
-
-<ul>
-	<li><code>philosopher</code>&nbsp;is the id of the philosopher who wants to eat.</li>
-	<li><code>pickLeftFork</code>&nbsp;and&nbsp;<code>pickRightFork</code>&nbsp;are functions you can call to pick the corresponding forks of that philosopher.</li>
-	<li><code>eat</code>&nbsp;is a function you can call to let the philosopher eat once he has picked&nbsp;both forks.</li>
-	<li><code>putLeftFork</code>&nbsp;and&nbsp;<code>putRightFork</code>&nbsp;are functions you can call to put down the corresponding forks of that philosopher.</li>
-	<li>The philosophers are assumed to be thinking as long as they are not asking to eat (the function is not being called with their number).</li>
-</ul>
-
-<p>Five threads, each representing a philosopher, will&nbsp;simultaneously use one object of your class to simulate the process. The function may be called for the same philosopher more than once, even before the last call ends.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> [[4,2,1],[4,1,1],[0,1,1],[2,2,1],[2,1,1],[2,0,3],[2,1,2],[2,2,2],[4,0,3],[4,1,2],[0,2,1],[4,2,2],[3,2,1],[3,1,1],[0,0,3],[0,1,2],[0,2,2],[1,2,1],[1,1,1],[3,0,3],[3,1,2],[3,2,2],[1,0,3],[1,1,2],[1,2,2]]
-<strong>Explanation:</strong>
-n is the number of times each philosopher will call the function.
-The output array describes the calls you made to the functions controlling the forks and the eat function, its format is:
-output[i] = [a, b, c] (three integers)
-- a is the id of a philosopher.
-- b specifies the fork: {1 : left, 2 : right}.
-- c specifies the operation: {1 : pick, 2 : put, 3 : eat}.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 60</code></li>
-</ul>
-
-### Related Topics
-  [[Concurrency](../../tag/concurrency/README.md)]
diff --git a/problems/the-earliest-and-latest-rounds-where-players-compete/README.md b/problems/the-earliest-and-latest-rounds-where-players-compete/README.md
deleted file mode 100644
index 21a5d1e92..000000000
--- a/problems/the-earliest-and-latest-rounds-where-players-compete/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../merge-triplets-to-form-target-triplet "Merge Triplets to Form Target Triplet")
-　　　　　　　　　　　　　　　　
-[Next >](../find-a-peak-element-ii "Find a Peak Element II")
-
-## [1900. The Earliest and Latest Rounds Where Players Compete (Hard)](https://leetcode.com/problems/the-earliest-and-latest-rounds-where-players-compete "最佳运动员的比拼回合")
-
-<p>There is a tournament where <code>n</code> players are participating. The players are standing in a single row and are numbered from <code>1</code> to <code>n</code> based on their <strong>initial</strong> standing position (player <code>1</code> is the first player in the row, player <code>2</code> is the second player in the row, etc.).</p>
-
-<p>The tournament consists of multiple rounds (starting from round number <code>1</code>). In each round, the <code>i<sup>th</sup></code> player from the front of the row competes against the <code>i<sup>th</sup></code> player from the end of the row, and the winner advances to the next round. When the number of players is odd for the current round, the player in the middle automatically advances to the next round.</p>
-
-<ul>
-	<li>For example, if the row consists of players <code>1, 2, 4, 6, 7</code>
-	<ul>
-		<li>Player <code>1</code> competes against player <code>7</code>.</li>
-		<li>Player <code>2</code> competes against player <code>6</code>.</li>
-		<li>Player <code>4</code> automatically advances to the next round.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>After each round is over, the winners are lined back up in the row based on the <strong>original ordering</strong> assigned to them initially (ascending order).</p>
-
-<p>The players numbered <code>firstPlayer</code> and <code>secondPlayer</code> are the best in the tournament. They can win against any other player before they compete against each other. If any two other players compete against each other, either of them might win, and thus you may <strong>choose</strong> the outcome of this round.</p>
-
-<p>Given the integers <code>n</code>, <code>firstPlayer</code>, and <code>secondPlayer</code>, return <em>an integer array containing two values, the <strong>earliest</strong> possible round number and the&nbsp;<strong>latest</strong> possible round number in which these two players will compete against each other, respectively</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 11, firstPlayer = 2, secondPlayer = 4
-<strong>Output:</strong> [3,4]
-<strong>Explanation:</strong>
-One possible scenario which leads to the earliest round number:
-First round: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
-Second round: 2, 3, 4, 5, 6, 11
-Third round: 2, 3, 4
-One possible scenario which leads to the latest round number:
-First round: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
-Second round: 1, 2, 3, 4, 5, 6
-Third round: 1, 2, 4
-Fourth round: 2, 4
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, firstPlayer = 1, secondPlayer = 5
-<strong>Output:</strong> [1,1]
-<strong>Explanation:</strong> The players numbered 1 and 5 compete in the first round.
-There is no way to make them compete in any other round.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= n &lt;= 28</code></li>
-	<li><code>1 &lt;= firstPlayer &lt; secondPlayer &lt;= n</code></li>
-</ul>
-
-### Related Topics
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Brute force using bitmasks and simulate the rounds.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Calculate each state one time and save its solution.
-</details>
diff --git a/problems/the-earliest-moment-when-everyone-become-friends/README.md b/problems/the-earliest-moment-when-everyone-become-friends/README.md
deleted file mode 100644
index 97e5581bb..000000000
--- a/problems/the-earliest-moment-when-everyone-become-friends/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-k-length-substrings-with-no-repeated-characters "Find K-Length Substrings With No Repeated Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../path-with-maximum-minimum-value "Path With Maximum Minimum Value")
-
-## [1101. The Earliest Moment When Everyone Become Friends (Medium)](https://leetcode.com/problems/the-earliest-moment-when-everyone-become-friends "彼此熟识的最早时间")
-
-<p>In a social group, there are <code>N</code> people, with unique integer ids from <code>0</code> to <code>N-1</code>.</p>
-
-<p>We have a list of <code>logs</code>, where each <code>logs[i] = [timestamp, id_A, id_B]</code> contains a non-negative&nbsp;integer timestamp, and the ids of two different people.</p>
-
-<p>Each log represents the time in which two different people became friends. &nbsp;Friendship is symmetric: if A is friends with B, then B is friends with A.</p>
-
-<p>Let&#39;s say that person A is acquainted with person B if A is friends with B, or A is a friend of someone acquainted with B.</p>
-
-<p>Return the earliest time for which every person became acquainted with every other person. Return -1 if there is no&nbsp;such&nbsp;earliest time.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>logs = <span id="example-input-1-1">[[20190101,0,1],[20190104,3,4],[20190107,2,3],[20190211,1,5],[20190224,2,4],[20190301,0,3],[20190312,1,2],[20190322,4,5]]</span>, N = <span id="example-input-1-2">6</span>
-<strong>Output: </strong><span id="example-output-1">20190301</span>
-<strong>Explanation: </strong>
-The first event occurs at timestamp = 20190101 and after 0 and 1 become friends we have the following friendship groups [0,1], [2], [3], [4], [5].
-The second event occurs at timestamp = 20190104 and after 3 and 4 become friends we have the following friendship groups [0,1], [2], [3,4], [5].
-The third event occurs at timestamp = 20190107 and after 2 and 3 become friends we have the following friendship groups [0,1], [2,3,4], [5].
-The fourth event occurs at timestamp = 20190211 and after 1 and 5 become friends we have the following friendship groups [0,1,5], [2,3,4].
-The fifth event occurs at timestamp = 20190224 and as 2 and 4 are already friend anything happens.
-The sixth event occurs at timestamp = 20190301 and after 0 and 3 become friends we have that all become friends.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= N &lt;= 100</code></li>
-	<li><code>1 &lt;= logs.length &lt;= 10^4</code></li>
-	<li><code>0 &lt;= logs[i][0] &lt;= 10^9</code></li>
-	<li><code>0 &lt;= logs[i][1], logs[i][2] &lt;= N - 1</code></li>
-	<li>It&#39;s guaranteed that all timestamps in logs[i][0] are different.</li>
-	<li><code>Logs </code>are not necessarily ordered by some criteria.</li>
-	<li><code>logs[i][1] != logs[i][2]</code></li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-
-### Similar Questions
-  1. [Number of Provinces](../number-of-provinces) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the log items by their timestamp.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we model this problem as a graph problem?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Let's use a union-find data structure. At the beginning we have a graph with N nodes but no edges.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Then we loop through the events and if unite each node until the number of connected components reach to 1. Notice that each time two different connected components are united the number of connected components decreases by 1.
-</details>
diff --git a/problems/the-k-strongest-values-in-an-array/README.md b/problems/the-k-strongest-values-in-an-array/README.md
deleted file mode 100644
index d063932a0..000000000
--- a/problems/the-k-strongest-values-in-an-array/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shuffle-the-array "Shuffle the Array")
-　　　　　　　　　　　　　　　　
-[Next >](../design-browser-history "Design Browser History")
-
-## [1471. The k Strongest Values in an Array (Medium)](https://leetcode.com/problems/the-k-strongest-values-in-an-array "数组中的 k 个最强值")
-
-<p>Given an array of integers <code>arr</code> and an integer <code>k</code>.</p>
-
-<p>A value <code>arr[i]</code> is said to be stronger than a value <code>arr[j]</code> if <code>|arr[i] - m| &gt; |arr[j] - m|</code> where <code>m</code> is the <strong>median</strong> of the array.<br />
-If <code>|arr[i] - m| == |arr[j] - m|</code>, then <code>arr[i]</code> is said to be stronger than <code>arr[j]</code> if <code>arr[i] &gt; arr[j]</code>.</p>
-
-<p>Return <em>a list of the strongest <code>k</code></em> values in the array. return the answer <strong>in any arbitrary order</strong>.</p>
-
-<p><strong>Median</strong> is the middle value in an ordered integer list. More formally, if the length of the list is n, the median is the element in position <code>((n - 1) / 2)</code> in the sorted list <strong>(0-indexed)</strong>.</p>
-
-<ul>
-	<li>For <code>arr = [6, -3, 7, 2, 11]</code>, <code>n = 5</code> and the median is obtained by sorting the array <code>arr = [-3, 2, 6, 7, 11]</code> and the median is <code>arr[m]</code> where <code>m = ((5 - 1) / 2) = 2</code>. The median is <code>6</code>.</li>
-	<li>For <code>arr = [-7, 22, 17,&thinsp;3]</code>, <code>n = 4</code> and the median is obtained by sorting the array <code>arr = [-7, 3, 17, 22]</code> and the median is <code>arr[m]</code> where <code>m = ((4 - 1) / 2) = 1</code>. The median is <code>3</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,3,4,5], k = 2
-<strong>Output:</strong> [5,1]
-<strong>Explanation:</strong> Median is 3, the elements of the array sorted by the strongest are [5,1,4,2,3]. The strongest 2 elements are [5, 1]. [1, 5] is also <strong>accepted</strong> answer.
-Please note that although |5 - 3| == |1 - 3| but 5 is stronger than 1 because 5 &gt; 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,1,3,5,5], k = 2
-<strong>Output:</strong> [5,5]
-<strong>Explanation:</strong> Median is 3, the elements of the array sorted by the strongest are [5,5,1,1,3]. The strongest 2 elements are [5, 5].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [6,7,11,7,6,8], k = 5
-<strong>Output:</strong> [11,8,6,6,7]
-<strong>Explanation:</strong> Median is 7, the elements of the array sorted by the strongest are [11,8,6,6,7,7].
-Any permutation of [11,8,6,6,7] is <strong>accepted</strong>.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>5</sup> &lt;= arr[i] &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= k &lt;= arr.length</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Calculate the median of the array as defined in the statement.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use custom sort function to sort values (Strongest first), then slice the first k.
-</details>
diff --git a/problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n/README.md b/problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n/README.md
deleted file mode 100644
index 099a3b76a..000000000
--- a/problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n/README.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k "Find the Minimum Number of Fibonacci Numbers Whose Sum Is K")
-　　　　　　　　　　　　　　　　
-[Next >](../restore-the-array "Restore The Array")
-
-## [1415. The k-th Lexicographical String of All Happy Strings of Length n (Medium)](https://leetcode.com/problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n "长度为 n 的开心字符串中字典序第 k 小的字符串")
-
-<p>A <strong>happy string</strong> is a string that:</p>
-
-<ul>
-	<li>consists only of letters of the set <code>[&#39;a&#39;, &#39;b&#39;, &#39;c&#39;]</code>.</li>
-	<li><code>s[i] != s[i + 1]</code>&nbsp;for all values of <code>i</code> from <code>1</code> to <code>s.length - 1</code> (string is 1-indexed).</li>
-</ul>
-
-<p>For example, strings <strong>&quot;abc&quot;, &quot;ac&quot;, &quot;b&quot;</strong> and <strong>&quot;abcbabcbcb&quot;</strong> are all happy strings and strings <strong>&quot;aa&quot;, &quot;baa&quot;</strong> and&nbsp;<strong>&quot;ababbc&quot;</strong> are not happy strings.</p>
-
-<p>Given two integers <code>n</code> and <code>k</code>, consider a list of all happy strings of length <code>n</code> sorted in lexicographical order.</p>
-
-<p>Return <em>the kth string</em> of this list or return an <strong>empty string</strong>&nbsp;if there are less than <code>k</code> happy strings of length <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, k = 3
-<strong>Output:</strong> &quot;c&quot;
-<strong>Explanation:</strong> The list [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;] contains all happy strings of length 1. The third string is &quot;c&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, k = 4
-<strong>Output:</strong> &quot;&quot;
-<strong>Explanation:</strong> There are only 3 happy strings of length 1.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, k = 9
-<strong>Output:</strong> &quot;cab&quot;
-<strong>Explanation:</strong> There are 12 different happy string of length 3 [&quot;aba&quot;, &quot;abc&quot;, &quot;aca&quot;, &quot;acb&quot;, &quot;bab&quot;, &quot;bac&quot;, &quot;bca&quot;, &quot;bcb&quot;, &quot;cab&quot;, &quot;cac&quot;, &quot;cba&quot;, &quot;cbc&quot;]. You will find the 9th string = &quot;cab&quot;
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2, k = 7
-<strong>Output:</strong> &quot;&quot;
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10, k = 100
-<strong>Output:</strong> &quot;abacbabacb&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10</code></li>
-	<li><code>1 &lt;= k &lt;= 100</code></li>
-</ul>
-
-<div id="vidyowebrtcscreenshare_is_installed">&nbsp;</div>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Generate recursively all the happy strings of length n.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Sort them in lexicographical order and return the kth string if it exists.
-</details>
diff --git a/problems/the-k-weakest-rows-in-a-matrix/README.md b/problems/the-k-weakest-rows-in-a-matrix/README.md
deleted file mode 100644
index 7c502a569..000000000
--- a/problems/the-k-weakest-rows-in-a-matrix/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-transactions-per-visit "Number of Transactions per Visit")
-　　　　　　　　　　　　　　　　
-[Next >](../reduce-array-size-to-the-half "Reduce Array Size to The Half")
-
-## [1337. The K Weakest Rows in a Matrix (Easy)](https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix "矩阵中战斗力最弱的 K 行")
-
-<p>You are given an <code>m x n</code> binary matrix <code>mat</code> of <code>1</code>&#39;s (representing soldiers) and <code>0</code>&#39;s (representing civilians). The soldiers are positioned <strong>in front</strong> of the civilians. That is, all the <code>1</code>&#39;s will appear to the <strong>left</strong> of all the <code>0</code>&#39;s in each row.</p>
-
-<p>A row <code>i</code> is <strong>weaker</strong> than a row <code>j</code> if one of the following is true:</p>
-
-<ul>
-	<li>The number of soldiers in row <code>i</code> is less than the number of soldiers in row <code>j</code>.</li>
-	<li>Both rows have the same number of soldiers and <code>i &lt; j</code>.</li>
-</ul>
-
-<p>Return <em>the indices of the </em><code>k</code><em> <strong>weakest</strong> rows in the matrix ordered from weakest to strongest</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = 
-[[1,1,0,0,0],
- [1,1,1,1,0],
- [1,0,0,0,0],
- [1,1,0,0,0],
- [1,1,1,1,1]], 
-k = 3
-<strong>Output:</strong> [2,0,3]
-<strong>Explanation:</strong> 
-The number of soldiers in each row is: 
-- Row 0: 2 
-- Row 1: 4 
-- Row 2: 1 
-- Row 3: 2 
-- Row 4: 5 
-The rows ordered from weakest to strongest are [2,0,3,1,4].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> mat = 
-[[1,0,0,0],
- [1,1,1,1],
- [1,0,0,0],
- [1,0,0,0]], 
-k = 2
-<strong>Output:</strong> [0,2]
-<strong>Explanation:</strong> 
-The number of soldiers in each row is: 
-- Row 0: 1 
-- Row 1: 4 
-- Row 2: 1 
-- Row 3: 1 
-The rows ordered from weakest to strongest are [0,2,3,1].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == mat.length</code></li>
-	<li><code>n == mat[i].length</code></li>
-	<li><code>2 &lt;= n, m &lt;= 100</code></li>
-	<li><code>1 &lt;= k &lt;= m</code></li>
-	<li><code>matrix[i][j]</code> is either 0 or 1.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the matrix row indexes by the number of soldiers and then row indexes.
-</details>
diff --git a/problems/the-kth-factor-of-n/README.md b/problems/the-kth-factor-of-n/README.md
deleted file mode 100644
index ce9c4a33b..000000000
--- a/problems/the-kth-factor-of-n/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../average-salary-excluding-the-minimum-and-maximum-salary "Average Salary Excluding the Minimum and Maximum Salary")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-subarray-of-1s-after-deleting-one-element "Longest Subarray of 1's After Deleting One Element")
-
-## [1492. The kth Factor of n (Medium)](https://leetcode.com/problems/the-kth-factor-of-n "n 的第 k 个因子")
-
-<p>You are given two positive integers <code>n</code> and <code>k</code>. A factor of an integer <code>n</code> is defined as an integer <code>i</code> where <code>n % i == 0</code>.</p>
-
-<p>Consider a list of all factors of <code>n</code> sorted in <strong>ascending order</strong>, return <em>the </em><code>k<sup>th</sup></code><em> factor</em> in this list or return <code>-1</code> if <code>n</code> has less than <code>k</code> factors.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 12, k = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Factors list is [1, 2, 3, 4, 6, 12], the 3<sup>rd</sup> factor is 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 7, k = 2
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> Factors list is [1, 7], the 2<sup>nd</sup> factor is 7.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, k = 4
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> Factors list is [1, 2, 4], there is only 3 factors. We should return -1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= k &lt;= n &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The factors of n will be always in the range [1, n].
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Keep a list of all factors sorted.  Loop i from 1 to n and add i if n % i == 0. Return the kth factor if it exist in this list.
-</details>
diff --git a/problems/the-latest-login-in-2020/README.md b/problems/the-latest-login-in-2020/README.md
deleted file mode 100644
index 09cab9b9a..000000000
--- a/problems/the-latest-login-in-2020/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-space-wasted-from-packaging "Minimum Space Wasted From Packaging")
-　　　　　　　　　　　　　　　　
-[Next >](../cutting-ribbons "Cutting Ribbons")
-
-## [1890. The Latest Login in 2020 (Easy)](https://leetcode.com/problems/the-latest-login-in-2020 "2020年最后一次登录")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/the-latest-login-in-2020/mysql_schemas.sql b/problems/the-latest-login-in-2020/mysql_schemas.sql
deleted file mode 100644
index feda94477..000000000
--- a/problems/the-latest-login-in-2020/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Logins (user_id int, time_stamp datetime);
-Truncate table Logins;
-insert into Logins (user_id, time_stamp) values ('6', '2020-06-30 15:06:07');
-insert into Logins (user_id, time_stamp) values ('6', '2021-04-21 14:06:06');
-insert into Logins (user_id, time_stamp) values ('6', '2019-03-07 00:18:15');
-insert into Logins (user_id, time_stamp) values ('8', '2020-02-01 05:10:53');
-insert into Logins (user_id, time_stamp) values ('8', '2020-12-30 00:46:50');
-insert into Logins (user_id, time_stamp) values ('2', '2020-01-16 02:49:50');
-insert into Logins (user_id, time_stamp) values ('2', '2019-08-25 07:59:08');
-insert into Logins (user_id, time_stamp) values ('14', '2019-07-14 09:00:00');
-insert into Logins (user_id, time_stamp) values ('14', '2021-01-06 11:59:59');
diff --git a/problems/the-maze-ii/README.md b/problems/the-maze-ii/README.md
deleted file mode 100644
index d9bc886f6..000000000
--- a/problems/the-maze-ii/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../base-7 "Base 7")
-　　　　　　　　　　　　　　　　
-[Next >](../relative-ranks "Relative Ranks")
-
-## [505. The Maze II (Medium)](https://leetcode.com/problems/the-maze-ii "迷宫 II")
-
-<p>There is a <b>ball</b> in a maze with empty spaces and walls. The ball can go through empty spaces by rolling <b>up</b>, <b>down</b>, <b>left</b> or <b>right</b>, but it won&#39;t stop rolling until hitting a wall. When the ball stops, it could choose the next direction.</p>
-
-<p>Given the ball&#39;s <b>start position</b>, the <b>destination</b> and the <b>maze</b>, find the shortest distance for the ball to stop at the destination. The distance is defined by the number of <b>empty spaces</b> traveled by the ball from the start position (excluded) to the destination (included). If the ball cannot stop at the destination, return -1.</p>
-
-<p>The maze is represented by a binary 2D array. 1 means the wall and 0 means the empty space. You may assume that the borders of the maze are all walls. The start and destination coordinates are represented by row and column indexes.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Example 1:</b></p>
-
-<pre><b>Input 1:</b> a maze represented by a 2D array
-
-0 0 1 0 0
-0 0 0 0 0
-0 0 0 1 0
-1 1 0 1 1
-0 0 0 0 0
-
-<b>Input 2:</b> start coordinate (rowStart, colStart) = (0, 4)
-<b>Input 3:</b> destination coordinate (rowDest, colDest) = (4, 4)
-
-<b>Output:</b> 12
-
-<b>Explanation:</b> One shortest way is : left -&gt; down -&gt; left -&gt; down -&gt; right -&gt; down -&gt; right.
-             The total distance is 1 + 1 + 3 + 1 + 2 + 2 + 2 = 12.
-<img src="https://assets.leetcode.com/uploads/2018/10/12/maze_1_example_1.png" style="width: 100%; max-width:350px;" />
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre><b>Input 1:</b> a maze represented by a 2D array
-
-0 0 1 0 0
-0 0 0 0 0
-0 0 0 1 0
-1 1 0 1 1
-0 0 0 0 0
-
-<b>Input 2:</b> start coordinate (rowStart, colStart) = (0, 4)
-<b>Input 3:</b> destination coordinate (rowDest, colDest) = (3, 2)
-
-<b>Output:</b> -1
-
-<b>Explanation:</b> There is no way for the ball to stop at the destination.
-<img src="https://assets.leetcode.com/uploads/2018/10/13/maze_1_example_2.png" style="width: 100%; max-width:350px;" />
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>There is only one ball and one destination in the maze.</li>
-	<li>Both the ball and the destination exist on an empty space, and they will not be at the same position initially.</li>
-	<li>The given maze does not contain border (like the red rectangle in the example pictures), but you could assume the border of the maze are all walls.</li>
-	<li>The maze contains at least 2 empty spaces, and both the width and height of the maze won&#39;t exceed 100.</li>
-</ol>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-
-### Similar Questions
-  1. [The Maze](../the-maze) (Medium)
-  1. [The Maze III](../the-maze-iii) (Hard)
diff --git a/problems/the-maze-ii/the_maze_ii.go b/problems/the-maze-ii/the_maze_ii.go
deleted file mode 100644
index 665a0d4d8..000000000
--- a/problems/the-maze-ii/the_maze_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem505
diff --git a/problems/the-maze-ii/the_maze_ii_test.go b/problems/the-maze-ii/the_maze_ii_test.go
deleted file mode 100644
index 665a0d4d8..000000000
--- a/problems/the-maze-ii/the_maze_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem505
diff --git a/problems/the-maze-iii/README.md b/problems/the-maze-iii/README.md
deleted file mode 100644
index 859b10015..000000000
--- a/problems/the-maze-iii/README.md
+++ /dev/null
@@ -1,85 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../diagonal-traverse "Diagonal Traverse")
-　　　　　　　　　　　　　　　　
-[Next >](../keyboard-row "Keyboard Row")
-
-## [499. The Maze III (Hard)](https://leetcode.com/problems/the-maze-iii "迷宫 III")
-
-<p>There is a <b>ball</b> in a maze with empty spaces and walls. The ball can go through empty spaces by rolling <b>up</b> (u), <b>down</b> (d), <b>left</b> (l) or <b>right</b> (r), but it won&#39;t stop rolling until hitting a wall. When the ball stops, it could choose the next direction. There is also a <b>hole</b> in this maze. The ball will drop into the hole if it rolls on to the hole.</p>
-
-<p>Given the <b>ball position</b>, the <b>hole position</b> and the <b>maze</b>, find out how the ball could drop into the hole by moving the <b>shortest distance</b>. The distance is defined by the number of <b>empty spaces</b> traveled by the ball from the start position (excluded) to the hole (included). Output the moving <b>directions</b> by using &#39;u&#39;, &#39;d&#39;, &#39;l&#39; and &#39;r&#39;. Since there could be several different shortest ways, you should output the <b>lexicographically smallest</b> way. If the ball cannot reach the hole, output &quot;impossible&quot;.</p>
-
-<p>The maze is represented by a binary 2D array. 1 means the wall and 0 means the empty space. You may assume that the borders of the maze are all walls. The ball and the hole coordinates are represented by row and column indexes.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Example 1:</b></p>
-
-<pre>
-<b>Input 1:</b> a maze represented by a 2D array
-
-0 0 0 0 0
-1 1 0 0 1
-0 0 0 0 0
-0 1 0 0 1
-0 1 0 0 0
-
-<b>Input 2:</b> ball coordinate (rowBall, colBall) = (4, 3)
-<b>Input 3:</b> hole coordinate (rowHole, colHole) = (0, 1)
-
-<b>Output:</b> &quot;lul&quot;
-
-<b>Explanation:</b> There are two shortest ways for the ball to drop into the hole.
-The first way is left -&gt; up -&gt; left, represented by &quot;lul&quot;.
-The second way is up -&gt; left, represented by &#39;ul&#39;.
-Both ways have shortest distance 6, but the first way is lexicographically smaller because &#39;l&#39; &lt; &#39;u&#39;. So the output is &quot;lul&quot;.
-<img src="https://assets.leetcode.com/uploads/2018/10/13/maze_2_example_1.png" style="width: 100%; max-width: 350px" />
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre>
-<b>Input 1:</b> a maze represented by a 2D array
-
-0 0 0 0 0
-1 1 0 0 1
-0 0 0 0 0
-0 1 0 0 1
-0 1 0 0 0
-
-<b>Input 2:</b> ball coordinate (rowBall, colBall) = (4, 3)
-<b>Input 3:</b> hole coordinate (rowHole, colHole) = (3, 0)
-
-<b>Output:</b> &quot;impossible&quot;
-
-<b>Explanation:</b> The ball cannot reach the hole.
-<img src="https://assets.leetcode.com/uploads/2018/10/13/maze_2_example_2.png" style="width: 100%; max-width: 350px" />
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>There is only one ball and one hole in the maze.</li>
-	<li>Both the ball and hole exist on an empty space, and they will not be at the same position initially.</li>
-	<li>The given maze does not contain border (like the red rectangle in the example pictures), but you could assume the border of the maze are all walls.</li>
-	<li>The maze contains at least 2 empty spaces, and the width and the height of the maze won&#39;t exceed 30.</li>
-</ol>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Shortest Path](../../tag/shortest-path/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [The Maze](../the-maze) (Medium)
-  1. [The Maze II](../the-maze-ii) (Medium)
diff --git a/problems/the-maze-iii/the_maze_iii.go b/problems/the-maze-iii/the_maze_iii.go
deleted file mode 100644
index f87abd276..000000000
--- a/problems/the-maze-iii/the_maze_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem499
diff --git a/problems/the-maze-iii/the_maze_iii_test.go b/problems/the-maze-iii/the_maze_iii_test.go
deleted file mode 100644
index f87abd276..000000000
--- a/problems/the-maze-iii/the_maze_iii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem499
diff --git a/problems/the-maze/README.md b/problems/the-maze/README.md
deleted file mode 100644
index 3f2eed321..000000000
--- a/problems/the-maze/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../robot-room-cleaner "Robot Room Cleaner")
-　　　　　　　　　　　　　　　　
-[Next >](../increasing-subsequences "Increasing Subsequences")
-
-## [490. The Maze (Medium)](https://leetcode.com/problems/the-maze "迷宫")
-
-<p>There is a <b>ball</b> in a maze with empty spaces and walls. The ball can go through empty spaces by rolling <b>up</b>, <b>down</b>, <b>left</b> or <b>right</b>, but it won&#39;t stop rolling until hitting a wall. When the ball stops, it could choose the next direction.</p>
-
-<p>Given the ball&#39;s <b>start position</b>, the <b>destination</b> and the <b>maze</b>, determine whether the ball could stop at the destination.</p>
-
-<p>The maze is represented by a binary 2D array. 1 means the wall and 0 means the empty space. You may assume that the borders of the maze are all walls. The start and destination coordinates are represented by row and column indexes.</p>
-
-<p>&nbsp;</p>
-
-<p><b>Example 1:</b></p>
-
-<pre><b>Input 1:</b> a maze represented by a 2D array
-
-0 0 1 0 0
-0 0 0 0 0
-0 0 0 1 0
-1 1 0 1 1
-0 0 0 0 0
-
-<b>Input 2:</b> start coordinate (rowStart, colStart) = (0, 4)
-<b>Input 3:</b> destination coordinate (rowDest, colDest) = (4, 4)
-
-<b>Output:</b> true
-
-<b>Explanation:</b> One possible way is : left -&gt; down -&gt; left -&gt; down -&gt; right -&gt; down -&gt; right.
-<img src="https://assets.leetcode.com/uploads/2018/10/12/maze_1_example_1.png" style="width: 100%; max-width:350px;" />
-</pre>
-
-<p><b>Example 2:</b></p>
-
-<pre><b>Input 1:</b> a maze represented by a 2D array
-
-0 0 1 0 0
-0 0 0 0 0
-0 0 0 1 0
-1 1 0 1 1
-0 0 0 0 0
-
-<b>Input 2:</b> start coordinate (rowStart, colStart) = (0, 4)
-<b>Input 3:</b> destination coordinate (rowDest, colDest) = (3, 2)
-
-<b>Output:</b> false
-
-<b>Explanation:</b> There is no way for the ball to stop at the destination.
-<img src="https://assets.leetcode.com/uploads/2018/10/13/maze_1_example_2.png" style="width: 100%; max-width:350px;" />
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Note:</b></p>
-
-<ol>
-	<li>There is only one ball and one destination in the maze.</li>
-	<li>Both the ball and the destination exist on an empty space, and they will not be at the same position initially.</li>
-	<li>The given maze does not contain border (like the red rectangle in the example pictures), but you could assume the border of the maze are all walls.</li>
-	<li>The maze contains at least 2 empty spaces, and both the width and height of the maze won&#39;t exceed 100.</li>
-</ol>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Similar Questions
-  1. [The Maze III](../the-maze-iii) (Hard)
-  1. [The Maze II](../the-maze-ii) (Medium)
diff --git a/problems/the-maze/the_maze.go b/problems/the-maze/the_maze.go
deleted file mode 100644
index dafead1d6..000000000
--- a/problems/the-maze/the_maze.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem490
diff --git a/problems/the-maze/the_maze_test.go b/problems/the-maze/the_maze_test.go
deleted file mode 100644
index dafead1d6..000000000
--- a/problems/the-maze/the_maze_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem490
diff --git a/problems/the-most-frequently-ordered-products-for-each-customer/README.md b/problems/the-most-frequently-ordered-products-for-each-customer/README.md
deleted file mode 100644
index e820d61c9..000000000
--- a/problems/the-most-frequently-ordered-products-for-each-customer/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-connect-two-groups-of-points "Minimum Cost to Connect Two Groups of Points")
-　　　　　　　　　　　　　　　　
-[Next >](../build-binary-expression-tree-from-infix-expression "Build Binary Expression Tree From Infix Expression")
-
-## [1596. The Most Frequently Ordered Products for Each Customer (Medium)](https://leetcode.com/problems/the-most-frequently-ordered-products-for-each-customer "每位顾客最经常订购的商品")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [The Most Recent Orders for Each Product](../the-most-recent-orders-for-each-product) (Medium)
diff --git a/problems/the-most-frequently-ordered-products-for-each-customer/mysql_schemas.sql b/problems/the-most-frequently-ordered-products-for-each-customer/mysql_schemas.sql
deleted file mode 100644
index 7294b609b..000000000
--- a/problems/the-most-frequently-ordered-products-for-each-customer/mysql_schemas.sql
+++ /dev/null
@@ -1,25 +0,0 @@
-Create table If Not Exists Customers (customer_id int, name varchar(10));
-Create table If Not Exists Orders (order_id int, order_date date, customer_id int, product_id int);
-Create table If Not Exists Products (product_id int, product_name varchar(20), price int);
-Truncate table Customers;
-insert into Customers (customer_id, name) values ('1', 'Alice');
-insert into Customers (customer_id, name) values ('2', 'Bob');
-insert into Customers (customer_id, name) values ('3', 'Tom');
-insert into Customers (customer_id, name) values ('4', 'Jerry');
-insert into Customers (customer_id, name) values ('5', 'John');
-Truncate table Orders;
-insert into Orders (order_id, order_date, customer_id, product_id) values ('1', '2020-07-31', '1', '1');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('2', '2020-7-30', '2', '2');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('3', '2020-08-29', '3', '3');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('4', '2020-07-29', '4', '1');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('5', '2020-06-10', '1', '2');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('6', '2020-08-01', '2', '1');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('7', '2020-08-01', '3', '3');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('8', '2020-08-03', '1', '2');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('9', '2020-08-07', '2', '3');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('10', '2020-07-15', '1', '2');
-Truncate table Products;
-insert into Products (product_id, product_name, price) values ('1', 'keyboard', '120');
-insert into Products (product_id, product_name, price) values ('2', 'mouse', '80');
-insert into Products (product_id, product_name, price) values ('3', 'screen', '600');
-insert into Products (product_id, product_name, price) values ('4', 'hard disk', '450');
diff --git a/problems/the-most-recent-orders-for-each-product/README.md b/problems/the-most-recent-orders-for-each-product/README.md
deleted file mode 100644
index 9eb2bee4d..000000000
--- a/problems/the-most-recent-orders-for-each-product/README.md
+++ /dev/null
@@ -1,21 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-most-similar-path-in-a-graph "The Most Similar Path in a Graph")
-　　　　　　　　　　　　　　　　
-[Next >](../three-consecutive-odds "Three Consecutive Odds")
-
-## [1549. The Most Recent Orders for Each Product (Medium)](https://leetcode.com/problems/the-most-recent-orders-for-each-product "每件商品的最新订单")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [The Most Recent Three Orders](../the-most-recent-three-orders) (Medium)
-  1. [The Most Frequently Ordered Products for Each Customer](../the-most-frequently-ordered-products-for-each-customer) (Medium)
diff --git a/problems/the-most-recent-orders-for-each-product/mysql_schemas.sql b/problems/the-most-recent-orders-for-each-product/mysql_schemas.sql
deleted file mode 100644
index 7da4f47bc..000000000
--- a/problems/the-most-recent-orders-for-each-product/mysql_schemas.sql
+++ /dev/null
@@ -1,25 +0,0 @@
-Create table If Not Exists Customers (customer_id int, name varchar(10));
-Create table If Not Exists Orders (order_id int, order_date date, customer_id int, product_id int);
-Create table If Not Exists Products (product_id int, product_name varchar(20), price int);
-Truncate table Customers;
-insert into Customers (customer_id, name) values ('1', 'Winston');
-insert into Customers (customer_id, name) values ('2', 'Jonathan');
-insert into Customers (customer_id, name) values ('3', 'Annabelle');
-insert into Customers (customer_id, name) values ('4', 'Marwan');
-insert into Customers (customer_id, name) values ('5', 'Khaled');
-Truncate table Orders;
-insert into Orders (order_id, order_date, customer_id, product_id) values ('1', '2020-07-31', '1', '1');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('2', '2020-7-30', '2', '2');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('3', '2020-08-29', '3', '3');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('4', '2020-07-29', '4', '1');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('5', '2020-06-10', '1', '2');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('6', '2020-08-01', '2', '1');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('7', '2020-08-01', '3', '1');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('8', '2020-08-03', '1', '2');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('9', '2020-08-07', '2', '3');
-insert into Orders (order_id, order_date, customer_id, product_id) values ('10', '2020-07-15', '1', '2');
-Truncate table Products;
-insert into Products (product_id, product_name, price) values ('1', 'keyboard', '120');
-insert into Products (product_id, product_name, price) values ('2', 'mouse', '80');
-insert into Products (product_id, product_name, price) values ('3', 'screen', '600');
-insert into Products (product_id, product_name, price) values ('4', 'hard disk', '450');
diff --git a/problems/the-most-recent-three-orders/README.md b/problems/the-most-recent-three-orders/README.md
deleted file mode 100644
index 992bd55db..000000000
--- a/problems/the-most-recent-three-orders/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../string-compression-ii "String Compression II")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-index-of-the-large-integer "Find the Index of the Large Integer")
-
-## [1532. The Most Recent Three Orders (Medium)](https://leetcode.com/problems/the-most-recent-three-orders "最近的三笔订单")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [The Most Recent Orders for Each Product](../the-most-recent-orders-for-each-product) (Medium)
diff --git a/problems/the-most-recent-three-orders/mysql_schemas.sql b/problems/the-most-recent-three-orders/mysql_schemas.sql
deleted file mode 100644
index 85541ef76..000000000
--- a/problems/the-most-recent-three-orders/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create table If Not Exists Customers (customer_id int, name varchar(10));
-Create table If Not Exists Orders (order_id int, order_date date, customer_id int, cost int);
-Truncate table Customers;
-insert into Customers (customer_id, name) values ('1', 'Winston');
-insert into Customers (customer_id, name) values ('2', 'Jonathan');
-insert into Customers (customer_id, name) values ('3', 'Annabelle');
-insert into Customers (customer_id, name) values ('4', 'Marwan');
-insert into Customers (customer_id, name) values ('5', 'Khaled');
-Truncate table Orders;
-insert into Orders (order_id, order_date, customer_id, cost) values ('1', '2020-07-31', '1', '30');
-insert into Orders (order_id, order_date, customer_id, cost) values ('2', '2020-7-30', '2', '40');
-insert into Orders (order_id, order_date, customer_id, cost) values ('3', '2020-07-31', '3', '70');
-insert into Orders (order_id, order_date, customer_id, cost) values ('4', '2020-07-29', '4', '100');
-insert into Orders (order_id, order_date, customer_id, cost) values ('5', '2020-06-10', '1', '1010');
-insert into Orders (order_id, order_date, customer_id, cost) values ('6', '2020-08-01', '2', '102');
-insert into Orders (order_id, order_date, customer_id, cost) values ('7', '2020-08-01', '3', '111');
-insert into Orders (order_id, order_date, customer_id, cost) values ('8', '2020-08-03', '1', '99');
-insert into Orders (order_id, order_date, customer_id, cost) values ('9', '2020-08-07', '2', '32');
-insert into Orders (order_id, order_date, customer_id, cost) values ('10', '2020-07-15', '1', '2');
diff --git a/problems/the-most-similar-path-in-a-graph/README.md b/problems/the-most-similar-path-in-a-graph/README.md
deleted file mode 100644
index f1f57b715..000000000
--- a/problems/the-most-similar-path-in-a-graph/README.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-cost-to-cut-a-stick "Minimum Cost to Cut a Stick")
-　　　　　　　　　　　　　　　　
-[Next >](../the-most-recent-orders-for-each-product "The Most Recent Orders for Each Product")
-
-## [1548. The Most Similar Path in a Graph (Hard)](https://leetcode.com/problems/the-most-similar-path-in-a-graph "图中最相似的路径")
-
-
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create an array dp where dp[i][j] is the min edit distance for the path starting at node i and compared to index j of the targetPath.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Traverse the dp array to obtain a valid answer.
-</details>
diff --git a/problems/the-number-of-employees-which-report-to-each-employee/README.md b/problems/the-number-of-employees-which-report-to-each-employee/README.md
deleted file mode 100644
index 8251eb140..000000000
--- a/problems/the-number-of-employees-which-report-to-each-employee/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-path-to-get-food "Shortest Path to Get Food")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-highest-altitude "Find the Highest Altitude")
-
-## [1731. The Number of Employees Which Report to Each Employee (Easy)](https://leetcode.com/problems/the-number-of-employees-which-report-to-each-employee "每位经理的下属员工数量")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/the-number-of-employees-which-report-to-each-employee/mysql_schemas.sql b/problems/the-number-of-employees-which-report-to-each-employee/mysql_schemas.sql
deleted file mode 100644
index a819253b1..000000000
--- a/problems/the-number-of-employees-which-report-to-each-employee/mysql_schemas.sql
+++ /dev/null
@@ -1,6 +0,0 @@
-Create table If Not Exists Employees(employee_id int, name varchar(20), reports_to int, age int);
-Truncate table Employees;
-insert into Employees (employee_id, name, reports_to, age) values ('9', 'Hercy', 'None', '43');
-insert into Employees (employee_id, name, reports_to, age) values ('6', 'Alice', '9', '41');
-insert into Employees (employee_id, name, reports_to, age) values ('4', 'Bob', '9', '36');
-insert into Employees (employee_id, name, reports_to, age) values ('2', 'Winston', 'None', '37');
diff --git a/problems/the-number-of-full-rounds-you-have-played/README.md b/problems/the-number-of-full-rounds-you-have-played/README.md
deleted file mode 100644
index 79d5b74f0..000000000
--- a/problems/the-number-of-full-rounds-you-have-played/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-odd-number-in-string "Largest Odd Number in String")
-　　　　　　　　　　　　　　　　
-[Next >](../count-sub-islands "Count Sub Islands")
-
-## [1904. The Number of Full Rounds You Have Played (Medium)](https://leetcode.com/problems/the-number-of-full-rounds-you-have-played "你完成的完整对局数")
-
-<p>You are participating in an online chess tournament. There is a chess round that starts every <code>15</code> minutes. The first round of the day starts at <code>00:00</code>, and after every <code>15</code> minutes, a new round starts.</p>
-
-<ul>
-	<li>For example, the second round starts at <code>00:15</code>, the fourth round starts at <code>00:45</code>, and the seventh round starts at <code>01:30</code>.</li>
-</ul>
-
-<p>You are given two strings <code>loginTime</code> and <code>logoutTime</code> where:</p>
-
-<ul>
-	<li><code>loginTime</code> is the time you will login to the game, and</li>
-	<li><code>logoutTime</code> is the time you will logout from the game.</li>
-</ul>
-
-<p>If <code>logoutTime</code> is <strong>earlier</strong> than <code>loginTime</code>, this means you have played from <code>loginTime</code> to midnight and from midnight to <code>logoutTime</code>.</p>
-
-<p>Return <em>the number of full chess rounds you have played in the tournament</em>.</p>
-
-<p><strong>Note:</strong>&nbsp;All the given times follow the 24-hour clock. That means the first round of the day starts at <code>00:00</code> and the last round of the day starts at <code>23:45</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> loginTime = &quot;09:31&quot;, logoutTime = &quot;10:14&quot;
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> You played one full round from 09:45 to 10:00.
-You did not play the full round from 09:30 to 09:45 because you logged in at 09:31 after it began.
-You did not play the full round from 10:00 to 10:15 because you logged out at 10:14 before it ended.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> loginTime = &quot;21:30&quot;, logoutTime = &quot;03:00&quot;
-<strong>Output:</strong> 22
-<strong>Explanation:</strong> You played 10 full rounds from 21:30 to 00:00 and 12 full rounds from 00:00 to 03:00.
-10 + 12 = 22.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>loginTime</code> and <code>logoutTime</code> are in the format <code>hh:mm</code>.</li>
-	<li><code>00 &lt;= hh &lt;= 23</code></li>
-	<li><code>00 &lt;= mm &lt;= 59</code></li>
-	<li><code>loginTime</code> and <code>logoutTime</code> are not equal.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider the day as 48 hours instead of 24.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For each round check if you were playing.
-</details>
diff --git a/problems/the-number-of-good-subsets/README.md b/problems/the-number-of-good-subsets/README.md
deleted file mode 100644
index 14eac458b..000000000
--- a/problems/the-number-of-good-subsets/README.md
+++ /dev/null
@@ -1,81 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../operations-on-tree "Operations on Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../count-special-quadruplets "Count Special Quadruplets")
-
-## [1994. The Number of Good Subsets (Hard)](https://leetcode.com/problems/the-number-of-good-subsets "好子集的数目")
-
-<p>You are given an integer array <code>nums</code>. We call a subset of <code>nums</code> <strong>good</strong> if its product can be represented as a product of one or more <strong>distinct prime</strong> numbers.</p>
-
-<ul>
-	<li>For example, if <code>nums = [1, 2, 3, 4]</code>:
-	<ul>
-		<li><code>[2, 3]</code>, <code>[1, 2, 3]</code>, and <code>[1, 3]</code> are <strong>good</strong> subsets with products <code>6 = 2*3</code>, <code>6 = 2*3</code>, and <code>3 = 3</code> respectively.</li>
-		<li><code>[1, 4]</code> and <code>[4]</code> are not <strong>good</strong> subsets with products <code>4 = 2*2</code> and <code>4 = 2*2</code> respectively.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>Return <em>the number of different <strong>good</strong> subsets in </em><code>nums</code><em> <strong>modulo</strong> </em><code>10<sup>9</sup> + 7</code>.</p>
-
-<p>A <strong>subset</strong> of <code>nums</code> is any array that can be obtained by deleting some (possibly none or all) elements from <code>nums</code>. Two subsets are different if and only if the chosen indices to delete are different.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The good subsets are:
-- [1,2]: product is 2, which is the product of distinct prime 2.
-- [1,2,3]: product is 6, which is the product of distinct primes 2 and 3.
-- [1,3]: product is 3, which is the product of distinct prime 3.
-- [2]: product is 2, which is the product of distinct prime 2.
-- [2,3]: product is 6, which is the product of distinct primes 2 and 3.
-- [3]: product is 3, which is the product of distinct prime 3.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,3,15]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The good subsets are:
-- [2]: product is 2, which is the product of distinct prime 2.
-- [2,3]: product is 6, which is the product of distinct primes 2 and 3.
-- [2,15]: product is 30, which is the product of distinct primes 2, 3, and 5.
-- [3]: product is 3, which is the product of distinct prime 3.
-- [15]: product is 15, which is the product of distinct primes 3 and 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 30</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Bitmask](../../tag/bitmask/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Consider only the numbers which have a good prime factorization.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use brute force to find all possible good subsets and then calculate its frequency in nums.
-</details>
diff --git a/problems/the-number-of-passengers-in-each-bus-i/README.md b/problems/the-number-of-passengers-in-each-bus-i/README.md
deleted file mode 100644
index 42c598909..000000000
--- a/problems/the-number-of-passengers-in-each-bus-i/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-running-time-of-n-computers "Maximum Running Time of N Computers")
-　　　　　　　　　　　　　　　　
-[Next >](../choose-numbers-from-two-arrays-in-range "Choose Numbers From Two Arrays in Range")
-
-## [2142. The Number of Passengers in Each Bus I (Medium)](https://leetcode.com/problems/the-number-of-passengers-in-each-bus-i "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/the-number-of-passengers-in-each-bus-i/mysql_schemas.sql b/problems/the-number-of-passengers-in-each-bus-i/mysql_schemas.sql
deleted file mode 100644
index 0fc11eefe..000000000
--- a/problems/the-number-of-passengers-in-each-bus-i/mysql_schemas.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-Create table If Not Exists Buses (bus_id int, arrival_time int);
-Create table If Not Exists Passengers (passenger_id int, arrival_time int);
-Truncate table Buses;
-insert into Buses (bus_id, arrival_time) values ('1', '2');
-insert into Buses (bus_id, arrival_time) values ('2', '4');
-insert into Buses (bus_id, arrival_time) values ('3', '7');
-Truncate table Passengers;
-insert into Passengers (passenger_id, arrival_time) values ('11', '1');
-insert into Passengers (passenger_id, arrival_time) values ('12', '5');
-insert into Passengers (passenger_id, arrival_time) values ('13', '6');
-insert into Passengers (passenger_id, arrival_time) values ('14', '7');
diff --git a/problems/the-number-of-passengers-in-each-bus-ii/README.md b/problems/the-number-of-passengers-in-each-bus-ii/README.md
deleted file mode 100644
index 55bbc3466..000000000
--- a/problems/the-number-of-passengers-in-each-bus-ii/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-lines-to-cover-points "Minimum Number of Lines to Cover Points")
-　　　　　　　　　　　　　　　　
-[Next >](../keep-multiplying-found-values-by-two "Keep Multiplying Found Values by Two")
-
-## [2153. The Number of Passengers in Each Bus II (Hard)](https://leetcode.com/problems/the-number-of-passengers-in-each-bus-ii "")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/the-number-of-passengers-in-each-bus-ii/mysql_schemas.sql b/problems/the-number-of-passengers-in-each-bus-ii/mysql_schemas.sql
deleted file mode 100644
index 58e4a205c..000000000
--- a/problems/the-number-of-passengers-in-each-bus-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Buses (bus_id int, arrival_time int, capacity int);
-Create table If Not Exists Passengers (passenger_id int, arrival_time int);
-Truncate table Buses;
-insert into Buses (bus_id, arrival_time, capacity) values ('1', '2', '1');
-insert into Buses (bus_id, arrival_time, capacity) values ('2', '4', '10');
-insert into Buses (bus_id, arrival_time, capacity) values ('3', '7', '2');
-Truncate table Passengers;
-insert into Passengers (passenger_id, arrival_time) values ('11', '1');
-insert into Passengers (passenger_id, arrival_time) values ('12', '1');
-insert into Passengers (passenger_id, arrival_time) values ('13', '5');
-insert into Passengers (passenger_id, arrival_time) values ('14', '6');
-insert into Passengers (passenger_id, arrival_time) values ('15', '7');
diff --git a/problems/the-number-of-rich-customers/README.md b/problems/the-number-of-rich-customers/README.md
deleted file mode 100644
index 9cde4d167..000000000
--- a/problems/the-number-of-rich-customers/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-k-mirror-numbers "Sum of k-Mirror Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../substrings-that-begin-and-end-with-the-same-letter "Substrings That Begin and End With the Same Letter")
-
-## [2082. The Number of Rich Customers (Easy)](https://leetcode.com/problems/the-number-of-rich-customers "富有客户的数量")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/the-number-of-rich-customers/mysql_schemas.sql b/problems/the-number-of-rich-customers/mysql_schemas.sql
deleted file mode 100644
index 63d1df440..000000000
--- a/problems/the-number-of-rich-customers/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Store (bill_id int, customer_id int, amount int);
-Truncate table Store;
-insert into Store (bill_id, customer_id, amount) values ('6', '1', '549');
-insert into Store (bill_id, customer_id, amount) values ('8', '1', '834');
-insert into Store (bill_id, customer_id, amount) values ('4', '2', '394');
-insert into Store (bill_id, customer_id, amount) values ('11', '3', '657');
-insert into Store (bill_id, customer_id, amount) values ('13', '3', '257');
diff --git a/problems/the-number-of-seniors-and-juniors-to-join-the-company-ii/README.md b/problems/the-number-of-seniors-and-juniors-to-join-the-company-ii/README.md
deleted file mode 100644
index 3ce1b5c42..000000000
--- a/problems/the-number-of-seniors-and-juniors-to-join-the-company-ii/README.md
+++ /dev/null
@@ -1,14 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-operations-to-make-array-continuous "Minimum Number of Operations to Make Array Continuous")
-　　　　　　　　　　　　　　　　
-[Next >](../final-value-of-variable-after-performing-operations "Final Value of Variable After Performing Operations")
-
-## [2010. The Number of Seniors and Juniors to Join the Company II (Hard)](https://leetcode.com/problems/the-number-of-seniors-and-juniors-to-join-the-company-ii "")
-
-
diff --git a/problems/the-number-of-seniors-and-juniors-to-join-the-company-ii/mysql_schemas.sql b/problems/the-number-of-seniors-and-juniors-to-join-the-company-ii/mysql_schemas.sql
deleted file mode 100644
index 998e0268a..000000000
--- a/problems/the-number-of-seniors-and-juniors-to-join-the-company-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Candidates (employee_id int, experience ENUM('Senior', 'Junior'), salary int);
-Truncate table Candidates;
-insert into Candidates (employee_id, experience, salary) values ('1', 'Junior', '10000');
-insert into Candidates (employee_id, experience, salary) values ('9', 'Junior', '15000');
-insert into Candidates (employee_id, experience, salary) values ('2', 'Senior', '20000');
-insert into Candidates (employee_id, experience, salary) values ('11', 'Senior', '16000');
-insert into Candidates (employee_id, experience, salary) values ('13', 'Senior', '50000');
-insert into Candidates (employee_id, experience, salary) values ('4', 'Junior', '40000');
diff --git a/problems/the-number-of-seniors-and-juniors-to-join-the-company/README.md b/problems/the-number-of-seniors-and-juniors-to-join-the-company/README.md
deleted file mode 100644
index b6d5ea3a4..000000000
--- a/problems/the-number-of-seniors-and-juniors-to-join-the-company/README.md
+++ /dev/null
@@ -1,14 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-missing-genetic-value-in-each-subtree "Smallest Missing Genetic Value in Each Subtree")
-　　　　　　　　　　　　　　　　
-[Next >](../subtree-removal-game-with-fibonacci-tree "Subtree Removal Game with Fibonacci Tree")
-
-## [2004. The Number of Seniors and Juniors to Join the Company (Hard)](https://leetcode.com/problems/the-number-of-seniors-and-juniors-to-join-the-company "")
-
-
diff --git a/problems/the-number-of-seniors-and-juniors-to-join-the-company/mysql_schemas.sql b/problems/the-number-of-seniors-and-juniors-to-join-the-company/mysql_schemas.sql
deleted file mode 100644
index a379f18ed..000000000
--- a/problems/the-number-of-seniors-and-juniors-to-join-the-company/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Candidates (employee_id int, experience ENUM('Senior', 'Junior'), salary int);
-Truncate table Candidates;
-insert into Candidates (employee_id, experience, salary) values ('1', 'Junior', '10000');
-insert into Candidates (employee_id, experience, salary) values ('9', 'Junior', '10000');
-insert into Candidates (employee_id, experience, salary) values ('2', 'Senior', '20000');
-insert into Candidates (employee_id, experience, salary) values ('11', 'Senior', '20000');
-insert into Candidates (employee_id, experience, salary) values ('13', 'Senior', '50000');
-insert into Candidates (employee_id, experience, salary) values ('4', 'Junior', '40000');
diff --git a/problems/the-number-of-the-smallest-unoccupied-chair/README.md b/problems/the-number-of-the-smallest-unoccupied-chair/README.md
deleted file mode 100644
index c5e38453c..000000000
--- a/problems/the-number-of-the-smallest-unoccupied-chair/README.md
+++ /dev/null
@@ -1,82 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-all-characters-have-equal-number-of-occurrences "Check if All Characters Have Equal Number of Occurrences")
-　　　　　　　　　　　　　　　　
-[Next >](../describe-the-painting "Describe the Painting")
-
-## [1942. The Number of the Smallest Unoccupied Chair (Medium)](https://leetcode.com/problems/the-number-of-the-smallest-unoccupied-chair "最小未被占据椅子的编号")
-
-<p>There is a party where <code>n</code> friends numbered from <code>0</code> to <code>n - 1</code> are attending. There is an <strong>infinite</strong> number of chairs in this party that are numbered from <code>0</code> to <code>infinity</code>. When a friend arrives at the party, they sit on the unoccupied chair with the <strong>smallest number</strong>.</p>
-
-<ul>
-	<li>For example, if chairs <code>0</code>, <code>1</code>, and <code>5</code> are occupied when a friend comes, they will sit on chair number <code>2</code>.</li>
-</ul>
-
-<p>When a friend leaves the party, their chair becomes unoccupied at the moment they leave. If another friend arrives at that same moment, they can sit in that chair.</p>
-
-<p>You are given a <strong>0-indexed</strong> 2D integer array <code>times</code> where <code>times[i] = [arrival<sub>i</sub>, leaving<sub>i</sub>]</code>, indicating the arrival and leaving times of the <code>i<sup>th</sup></code> friend respectively, and an integer <code>targetFriend</code>. All arrival times are <strong>distinct</strong>.</p>
-
-<p>Return<em> the <strong>chair number</strong> that the friend numbered </em><code>targetFriend</code><em> will sit on</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> times = [[1,4],[2,3],[4,6]], targetFriend = 1
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 
-- Friend 0 arrives at time 1 and sits on chair 0.
-- Friend 1 arrives at time 2 and sits on chair 1.
-- Friend 1 leaves at time 3 and chair 1 becomes empty.
-- Friend 0 leaves at time 4 and chair 0 becomes empty.
-- Friend 2 arrives at time 4 and sits on chair 0.
-Since friend 1 sat on chair 1, we return 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> times = [[3,10],[1,5],[2,6]], targetFriend = 0
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> 
-- Friend 1 arrives at time 1 and sits on chair 0.
-- Friend 2 arrives at time 2 and sits on chair 1.
-- Friend 0 arrives at time 3 and sits on chair 2.
-- Friend 1 leaves at time 5 and chair 0 becomes empty.
-- Friend 2 leaves at time 6 and chair 1 becomes empty.
-- Friend 0 leaves at time 10 and chair 2 becomes empty.
-Since friend 0 sat on chair 2, we return 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == times.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>times[i].length == 2</code></li>
-	<li><code>1 &lt;= arrival<sub>i</sub> &lt; leaving<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= targetFriend &lt;= n - 1</code></li>
-	<li>Each <code>arrival<sub>i</sub></code> time is <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort times by arrival time.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-for each arrival_i find the smallest unoccupied chair and mark it as occupied until leaving_i.
-</details>
diff --git a/problems/the-number-of-weak-characters-in-the-game/README.md b/problems/the-number-of-weak-characters-in-the-game/README.md
deleted file mode 100644
index 86f87d699..000000000
--- a/problems/the-number-of-weak-characters-in-the-game/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-special-quadruplets "Count Special Quadruplets")
-　　　　　　　　　　　　　　　　
-[Next >](../first-day-where-you-have-been-in-all-the-rooms "First Day Where You Have Been in All the Rooms")
-
-## [1996. The Number of Weak Characters in the Game (Medium)](https://leetcode.com/problems/the-number-of-weak-characters-in-the-game "游戏中弱角色的数量")
-
-<p>You are playing a game that contains multiple characters, and each of the characters has <strong>two</strong> main properties: <strong>attack</strong> and <strong>defense</strong>. You are given a 2D integer array <code>properties</code> where <code>properties[i] = [attack<sub>i</sub>, defense<sub>i</sub>]</code> represents the properties of the <code>i<sup>th</sup></code> character in the game.</p>
-
-<p>A character is said to be <strong>weak</strong> if any other character has <strong>both</strong> attack and defense levels <strong>strictly greater</strong> than this character&#39;s attack and defense levels. More formally, a character <code>i</code> is said to be <strong>weak</strong> if there exists another character <code>j</code> where <code>attack<sub>j</sub> &gt; attack<sub>i</sub></code> and <code>defense<sub>j</sub> &gt; defense<sub>i</sub></code>.</p>
-
-<p>Return <em>the number of <strong>weak</strong> characters</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> properties = [[5,5],[6,3],[3,6]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> No character has strictly greater attack and defense than the other.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> properties = [[2,2],[3,3]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The first character is weak because the second character has a strictly greater attack and defense.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> properties = [[1,5],[10,4],[4,3]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The third character is weak because the second character has a strictly greater attack and defense.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= properties.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>properties[i].length == 2</code></li>
-	<li><code>1 &lt;= attack<sub>i</sub>, defense<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Sort the array on the basis of the attack values and group characters with the same attack together. How can you use these groups?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Characters in one group will always have a lesser attack value than the characters of the next group. Hence, we will only need to check if there is a higher defense value present in the next groups.
-</details>
diff --git a/problems/the-score-of-students-solving-math-expression/README.md b/problems/the-score-of-students-solving-math-expression/README.md
deleted file mode 100644
index d6b8d68bc..000000000
--- a/problems/the-score-of-students-solving-math-expression/README.md
+++ /dev/null
@@ -1,99 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-if-word-can-be-placed-in-crossword "Check if Word Can Be Placed In Crossword")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-accounts-that-did-not-stream "Number of Accounts That Did Not Stream")
-
-## [2019. The Score of Students Solving Math Expression (Hard)](https://leetcode.com/problems/the-score-of-students-solving-math-expression "解出数学表达式的学生分数")
-
-<p>You are given a string <code>s</code> that contains digits <code>0-9</code>, addition symbols <code>&#39;+&#39;</code>, and multiplication symbols <code>&#39;*&#39;</code> <strong>only</strong>, representing a <strong>valid</strong> math expression of <strong>single digit numbers</strong> (e.g., <code>3+5*2</code>). This expression was given to <code>n</code> elementary school students. The students were instructed to get the answer of the expression by following this <strong>order of operations</strong>:</p>
-
-<ol>
-	<li>Compute <strong>multiplication</strong>, reading from <strong>left to right</strong>; Then,</li>
-	<li>Compute <strong>addition</strong>, reading from <strong>left to right</strong>.</li>
-</ol>
-
-<p>You are given an integer array <code>answers</code> of length <code>n</code>, which are the submitted answers of the students in no particular order. You are asked to grade the <code>answers</code>, by following these <strong>rules</strong>:</p>
-
-<ul>
-	<li>If an answer <strong>equals</strong> the correct answer of the expression, this student will be rewarded <code>5</code> points;</li>
-	<li>Otherwise, if the answer <strong>could be interpreted</strong> as if the student applied the operators <strong>in the wrong order</strong> but had <strong>correct arithmetic</strong>, this student will be rewarded <code>2</code> points;</li>
-	<li>Otherwise, this student will be rewarded <code>0</code> points.</li>
-</ul>
-
-<p>Return <em>the sum of the points of the students</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/17/student_solving_math.png" style="width: 678px; height: 109px;" />
-<pre>
-<strong>Input:</strong> s = &quot;7+3*1*2&quot;, answers = [20,13,42]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> As illustrated above, the correct answer of the expression is 13, therefore one student is rewarded 5 points: [20,<u><strong>13</strong></u>,42]
-A student might have applied the operators in this wrong order: ((7+3)*1)*2 = 20. Therefore one student is rewarded 2 points: [<u><strong>20</strong></u>,13,42]
-The points for the students are: [2,5,0]. The sum of the points is 2+5+0=7.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;3+5*2&quot;, answers = [13,0,10,13,13,16,16]
-<strong>Output:</strong> 19
-<strong>Explanation:</strong> The correct answer of the expression is 13, therefore three students are rewarded 5 points each: [<strong><u>13</u></strong>,0,10,<strong><u>13</u></strong>,<strong><u>13</u></strong>,16,16]
-A student might have applied the operators in this wrong order: ((3+5)*2 = 16. Therefore two students are rewarded 2 points: [13,0,10,13,13,<strong><u>16</u></strong>,<strong><u>16</u></strong>]
-The points for the students are: [5,0,0,5,5,2,2]. The sum of the points is 5+0+0+5+5+2+2=19.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;6+0*1&quot;, answers = [12,9,6,4,8,6]
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> The correct answer of the expression is 6.
-If a student had incorrectly done (6+0)*1, the answer would also be 6.
-By the rules of grading, the students will still be rewarded 5 points (as they got the correct answer), not 2 points.
-The points for the students are: [0,0,5,0,0,5]. The sum of the points is 10.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= s.length &lt;= 31</code></li>
-	<li><code>s</code> represents a valid expression that contains only digits <code>0-9</code>, <code>&#39;+&#39;</code>, and <code>&#39;*&#39;</code> only.</li>
-	<li>All the integer operands in the expression are in the <strong>inclusive</strong> range <code>[0, 9]</code>.</li>
-	<li><code>1 &lt;=</code> The count of all operators (<code>&#39;+&#39;</code> and <code>&#39;*&#39;</code>) in the math expression <code>&lt;= 15</code></li>
-	<li>Test data are generated such that the correct answer of the expression is in the range of <code>[0, 1000]</code>.</li>
-	<li><code>n == answers.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= answers[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The number of operators in the equation is less. Could you find the right answer then generate all possible answers using different orders of operations?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Divide the equation into blocks separated by the operators, and use memoization on the results of blocks for optimization.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use set and the max limit of the answer for further optimization.
-</details>
diff --git a/problems/the-skyline-problem/README.md b/problems/the-skyline-problem/README.md
deleted file mode 100644
index 769f51184..000000000
--- a/problems/the-skyline-problem/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../contains-duplicate "Contains Duplicate")
-　　　　　　　　　　　　　　　　
-[Next >](../contains-duplicate-ii "Contains Duplicate II")
-
-## [218. The Skyline Problem (Hard)](https://leetcode.com/problems/the-skyline-problem "天际线问题")
-
-<p>A city&#39;s <strong>skyline</strong> is the outer contour of the silhouette formed by all the buildings in that city when viewed from a distance. Given the locations and heights of all the buildings, return <em>the <strong>skyline</strong> formed by these buildings collectively</em>.</p>
-
-<p>The geometric information of each building is given in the array <code>buildings</code> where <code>buildings[i] = [left<sub>i</sub>, right<sub>i</sub>, height<sub>i</sub>]</code>:</p>
-
-<ul>
-	<li><code>left<sub>i</sub></code> is the x coordinate of the left edge of the <code>i<sup>th</sup></code> building.</li>
-	<li><code>right<sub>i</sub></code> is the x coordinate of the right edge of the <code>i<sup>th</sup></code> building.</li>
-	<li><code>height<sub>i</sub></code> is the height of the <code>i<sup>th</sup></code> building.</li>
-</ul>
-
-<p>You may assume all buildings are perfect rectangles grounded on an absolutely flat surface at height <code>0</code>.</p>
-
-<p>The <strong>skyline</strong> should be represented as a list of &quot;key points&quot; <strong>sorted by their x-coordinate</strong> in the form <code>[[x<sub>1</sub>,y<sub>1</sub>],[x<sub>2</sub>,y<sub>2</sub>],...]</code>. Each key point is the left endpoint of some horizontal segment in the skyline except the last point in the list, which always has a y-coordinate <code>0</code> and is used to mark the skyline&#39;s termination where the rightmost building ends. Any ground between the leftmost and rightmost buildings should be part of the skyline&#39;s contour.</p>
-
-<p><b>Note:</b> There must be no consecutive horizontal lines of equal height in the output skyline. For instance, <code>[...,[2 3],[4 5],[7 5],[11 5],[12 7],...]</code> is not acceptable; the three lines of height 5 should be merged into one in the final output as such: <code>[...,[2 3],[4 5],[12 7],...]</code></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/01/merged.jpg" style="width: 800px; height: 331px;" />
-<pre>
-<strong>Input:</strong> buildings = [[2,9,10],[3,7,15],[5,12,12],[15,20,10],[19,24,8]]
-<strong>Output:</strong> [[2,10],[3,15],[7,12],[12,0],[15,10],[20,8],[24,0]]
-<strong>Explanation:</strong>
-Figure A shows the buildings of the input.
-Figure B shows the skyline formed by those buildings. The red points in figure B represent the key points in the output list.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> buildings = [[0,2,3],[2,5,3]]
-<strong>Output:</strong> [[0,3],[5,0]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= buildings.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= left<sub>i</sub> &lt; right<sub>i</sub> &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>1 &lt;= height<sub>i</sub> &lt;= 2<sup>31</sup> - 1</code></li>
-	<li><code>buildings</code> is sorted by <code>left<sub>i</sub></code> in&nbsp;non-decreasing order.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Binary Indexed Tree](../../tag/binary-indexed-tree/README.md)]
-  [[Segment Tree](../../tag/segment-tree/README.md)]
-  [[Line Sweep](../../tag/line-sweep/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-
-### Similar Questions
-  1. [Falling Squares](../falling-squares) (Hard)
diff --git a/problems/the-skyline-problem/the_skyline_problem.go b/problems/the-skyline-problem/the_skyline_problem.go
deleted file mode 100644
index 45fcd259f..000000000
--- a/problems/the-skyline-problem/the_skyline_problem.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem218
diff --git a/problems/the-skyline-problem/the_skyline_problem_test.go b/problems/the-skyline-problem/the_skyline_problem_test.go
deleted file mode 100644
index 45fcd259f..000000000
--- a/problems/the-skyline-problem/the_skyline_problem_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem218
diff --git a/problems/the-time-when-the-network-becomes-idle/README.md b/problems/the-time-when-the-network-becomes-idle/README.md
deleted file mode 100644
index e3b5677b0..000000000
--- a/problems/the-time-when-the-network-becomes-idle/README.md
+++ /dev/null
@@ -1,105 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-colored-pieces-if-both-neighbors-are-the-same-color "Remove Colored Pieces if Both Neighbors are the Same Color")
-　　　　　　　　　　　　　　　　
-[Next >](../kth-smallest-product-of-two-sorted-arrays "Kth Smallest Product of Two Sorted Arrays")
-
-## [2039. The Time When the Network Becomes Idle (Medium)](https://leetcode.com/problems/the-time-when-the-network-becomes-idle "网络空闲的时刻")
-
-<p>There is a network of <code>n</code> servers, labeled from <code>0</code> to <code>n - 1</code>. You are given a 2D integer array <code>edges</code>, where <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> indicates there is a message channel between servers <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code>, and they can pass <strong>any</strong> number of messages to <strong>each other</strong> directly in <strong>one</strong> second. You are also given a <strong>0-indexed</strong> integer array <code>patience</code> of length <code>n</code>.</p>
-
-<p>All servers are <strong>connected</strong>, i.e., a message can be passed from one server to any other server(s) directly or indirectly through the message channels.</p>
-
-<p>The server labeled <code>0</code> is the <strong>master</strong> server. The rest are <strong>data</strong> servers. Each data server needs to send its message to the master server for processing and wait for a reply. Messages move between servers <strong>optimally</strong>, so every message takes the <strong>least amount of time</strong> to arrive at the master server. The master server will process all newly arrived messages <strong>instantly</strong> and send a reply to the originating server via the <strong>reversed path</strong> the message had gone through.</p>
-
-<p>At the beginning of second <code>0</code>, each data server sends its message to be processed. Starting from second <code>1</code>, at the <strong>beginning</strong> of <strong>every</strong> second, each data server will check if it has received a reply to the message it sent (including any newly arrived replies) from the master server:</p>
-
-<ul>
-	<li>If it has not, it will <strong>resend</strong> the message periodically. The data server <code>i</code> will resend the message every <code>patience[i]</code> second(s), i.e., the data server <code>i</code> will resend the message if <code>patience[i]</code> second(s) have <strong>elapsed</strong> since the <strong>last</strong> time the message was sent from this server.</li>
-	<li>Otherwise, <strong>no more resending</strong> will occur from this server.</li>
-</ul>
-
-<p>The network becomes <strong>idle</strong> when there are <strong>no</strong> messages passing between servers or arriving at servers.</p>
-
-<p>Return <em>the <strong>earliest second</strong> starting from which the network becomes <strong>idle</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="example 1" src="https://assets.leetcode.com/uploads/2021/09/22/quiet-place-example1.png" style="width: 750px; height: 384px;" />
-<pre>
-<strong>Input:</strong> edges = [[0,1],[1,2]], patience = [0,2,1]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong>
-At (the beginning of) second 0,
-- Data server 1 sends its message (denoted 1A) to the master server.
-- Data server 2 sends its message (denoted 2A) to the master server.
-
-At second 1,
-- Message 1A arrives at the master server. Master server processes message 1A instantly and sends a reply 1A back.
-- Server 1 has not received any reply. 1 second (1 &lt; patience[1] = 2) elapsed since this server has sent the message, therefore it does not resend the message.
-- Server 2 has not received any reply. 1 second (1 == patience[2] = 1) elapsed since this server has sent the message, therefore it resends the message (denoted 2B).
-
-At second 2,
-- The reply 1A arrives at server 1. No more resending will occur from server 1.
-- Message 2A arrives at the master server. Master server processes message 2A instantly and sends a reply 2A back.
-- Server 2 resends the message (denoted 2C).
-...
-At second 4,
-- The reply 2A arrives at server 2. No more resending will occur from server 2.
-...
-At second 7, reply 2D arrives at server 2.
-
-Starting from the beginning of the second 8, there are no messages passing between servers or arriving at servers.
-This is the time when the network becomes idle.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="example 2" src="https://assets.leetcode.com/uploads/2021/09/04/network_a_quiet_place_2.png" style="width: 100px; height: 85px;" />
-<pre>
-<strong>Input:</strong> edges = [[0,1],[0,2],[1,2]], patience = [0,10,10]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Data servers 1 and 2 receive a reply back at the beginning of second 2.
-From the beginning of the second 3, the network becomes idle.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == patience.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>patience[0] == 0</code></li>
-	<li><code>1 &lt;= patience[i] &lt;= 10<sup>5</sup></code> for <code>1 &lt;= i &lt; n</code></li>
-	<li><code>1 &lt;= edges.length &lt;= min(10<sup>5</sup>, n * (n - 1) / 2)</code></li>
-	<li><code>edges[i].length == 2</code></li>
-	<li><code>0 &lt;= u<sub>i</sub>, v<sub>i</sub> &lt; n</code></li>
-	<li><code>u<sub>i</sub> != v<sub>i</sub></code></li>
-	<li>There are no duplicate edges.</li>
-	<li>Each server can directly or indirectly reach another server.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What method can you use to find the shortest time taken for a message from a data server to reach the master server? How can you use this value and the server's patience value to determine the time at which the server sends its last message?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What is the time when the last message sent from a server gets back to the server?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-For each data server, by the time the server receives the first returned messages, how many messages has the server sent?
-</details>
diff --git a/problems/the-winner-university/README.md b/problems/the-winner-university/README.md
deleted file mode 100644
index 569867b73..000000000
--- a/problems/the-winner-university/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-tasks-you-can-assign "Maximum Number of Tasks You Can Assign")
-　　　　　　　　　　　　　　　　
-[Next >](../time-needed-to-buy-tickets "Time Needed to Buy Tickets")
-
-## [2072. The Winner University (Easy)](https://leetcode.com/problems/the-winner-university "赢得比赛的大学")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/the-winner-university/mysql_schemas.sql b/problems/the-winner-university/mysql_schemas.sql
deleted file mode 100644
index a1aefcc9b..000000000
--- a/problems/the-winner-university/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists NewYork (student_id int, score int);
-Create table If Not Exists California (student_id int, score int);
-Truncate table NewYork;
-insert into NewYork (student_id, score) values ('1', '90');
-insert into NewYork (student_id, score) values ('2', '87');
-Truncate table California;
-insert into California (student_id, score) values ('2', '89');
-insert into California (student_id, score) values ('3', '88');
diff --git a/problems/third-maximum-number/README.md b/problems/third-maximum-number/README.md
deleted file mode 100644
index d7b315550..000000000
--- a/problems/third-maximum-number/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../arithmetic-slices "Arithmetic Slices")
-　　　　　　　　　　　　　　　　
-[Next >](../add-strings "Add Strings")
-
-## [414. Third Maximum Number (Easy)](https://leetcode.com/problems/third-maximum-number "第三大的数")
-
-<p>Given an integer array <code>nums</code>, return <em>the <strong>third distinct maximum</strong> number in this array. If the third maximum does not exist, return the <strong>maximum</strong> number</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-The first distinct maximum is 3.
-The second distinct maximum is 2.
-The third distinct maximum is 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-The first distinct maximum is 2.
-The second distinct maximum is 1.
-The third distinct maximum does not exist, so the maximum (2) is returned instead.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,3,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-The first distinct maximum is 3.
-The second distinct maximum is 2 (both 2&#39;s are counted together since they have the same value).
-The third distinct maximum is 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Can you find an <code>O(n)</code> solution?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Kth Largest Element in an Array](../kth-largest-element-in-an-array) (Medium)
diff --git a/problems/third-maximum-number/third_maximum_number.go b/problems/third-maximum-number/third_maximum_number.go
deleted file mode 100644
index dec9633c1..000000000
--- a/problems/third-maximum-number/third_maximum_number.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package problem414
-
-func thirdMax(nums []int) int {
-	max1, max2, max3 := 0, -1, -1
-	for i, v := range nums {
-		if v > nums[max1] {
-			max1, max2, max3 = i, max1, max2
-		} else if (max2 == -1 || v > nums[max2]) && v != nums[max1] {
-			max2, max3 = i, max2
-		} else if (max3 == -1 || v > nums[max3]) && v != nums[max1] && v != nums[max2] {
-			max3 = i
-		}
-	}
-	if max3 == -1 {
-		return nums[max1]
-	}
-	return nums[max3]
-}
diff --git a/problems/third-maximum-number/third_maximum_number_test.go b/problems/third-maximum-number/third_maximum_number_test.go
deleted file mode 100644
index 86338922d..000000000
--- a/problems/third-maximum-number/third_maximum_number_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem414
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want int
-}
-
-func TestThirdMax(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 2, 5, 3, 5},
-			want: 2,
-		},
-		{
-			in:   []int{1, 2, 2},
-			want: 2,
-		},
-		{
-			in:   []int{1, 1, 2},
-			want: 2,
-		},
-		{
-			in:   []int{3, 2, 1},
-			want: 1,
-		},
-		{
-			in:   []int{1, 2},
-			want: 2,
-		},
-		{
-			in:   []int{2, 2, 3, 1},
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := thirdMax(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/thousand-separator/README.md b/problems/thousand-separator/README.md
deleted file mode 100644
index 87bf7dfd4..000000000
--- a/problems/thousand-separator/README.md
+++ /dev/null
@@ -1,45 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bank-account-summary "Bank Account Summary")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-number-of-vertices-to-reach-all-nodes "Minimum Number of Vertices to Reach All Nodes")
-
-## [1556. Thousand Separator (Easy)](https://leetcode.com/problems/thousand-separator "千位分隔数")
-
-<p>Given an integer <code>n</code>, add a dot (&quot;.&quot;) as the thousands separator and return it in string format.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 987
-<strong>Output:</strong> &quot;987&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1234
-<strong>Output:</strong> &quot;1.234&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Scan from the back of the integer and use dots to connect blocks with length 3 except the last block.
-</details>
diff --git a/problems/three-consecutive-odds/README.md b/problems/three-consecutive-odds/README.md
deleted file mode 100644
index fae398752..000000000
--- a/problems/three-consecutive-odds/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-most-recent-orders-for-each-product "The Most Recent Orders for Each Product")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-operations-to-make-array-equal "Minimum Operations to Make Array Equal")
-
-## [1550. Three Consecutive Odds (Easy)](https://leetcode.com/problems/three-consecutive-odds "存在连续三个奇数的数组")
-
-Given an integer array <code>arr</code>, return <code>true</code>&nbsp;if there are three consecutive odd numbers in the array. Otherwise, return&nbsp;<code>false</code>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [2,6,4,1]
-<strong>Output:</strong> false
-<b>Explanation:</b> There are no three consecutive odds.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,34,3,4,5,7,23,12]
-<strong>Output:</strong> true
-<b>Explanation:</b> [5,7,23] are three consecutive odds.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check every three consecutive numbers in the array for parity.
-</details>
diff --git a/problems/three-divisors/README.md b/problems/three-divisors/README.md
deleted file mode 100644
index cc81d110e..000000000
--- a/problems/three-divisors/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../all-the-pairs-with-the-maximum-number-of-common-followers "All the Pairs With the Maximum Number of Common Followers")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-weeks-for-which-you-can-work "Maximum Number of Weeks for Which You Can Work")
-
-## [1952. Three Divisors (Easy)](https://leetcode.com/problems/three-divisors "三除数")
-
-<p>Given an integer <code>n</code>, return <code>true</code><em> if </em><code>n</code><em> has <strong>exactly three positive divisors</strong>. Otherwise, return </em><code>false</code>.</p>
-
-<p>An integer <code>m</code> is a <strong>divisor</strong> of <code>n</code> if there exists an integer <code>k</code> such that <code>n = k * m</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 2
-<strong>Output:</strong> false
-<strong>Explantion:</strong> 2 has only two divisors: 1 and 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4
-<strong>Output:</strong> true
-<strong>Explantion:</strong> 4 has three divisors: 1, 2, and 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Find Greatest Common Divisor of Array](../find-greatest-common-divisor-of-array) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can count the number of divisors and just check that they are 3
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Beware of the case of n equal 1 as some solutions might fail in it
-</details>
diff --git a/problems/three-equal-parts/README.md b/problems/three-equal-parts/README.md
deleted file mode 100644
index 275dd7810..000000000
--- a/problems/three-equal-parts/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../flip-string-to-monotone-increasing "Flip String to Monotone Increasing")
-　　　　　　　　　　　　　　　　
-[Next >](../minimize-malware-spread-ii "Minimize Malware Spread II")
-
-## [927. Three Equal Parts (Hard)](https://leetcode.com/problems/three-equal-parts "三等分")
-
-<p>You are given an array <code>arr</code> which consists of only zeros and ones, divide the array into <strong>three non-empty parts</strong> such that all of these parts represent the same binary value.</p>
-
-<p>If it is possible, return any <code>[i, j]</code> with <code>i + 1 &lt; j</code>, such that:</p>
-
-<ul>
-	<li><code>arr[0], arr[1], ..., arr[i]</code> is the first part,</li>
-	<li><code>arr[i + 1], arr[i + 2], ..., arr[j - 1]</code> is the second part, and</li>
-	<li><code>arr[j], arr[j + 1], ..., arr[arr.length - 1]</code> is the third part.</li>
-	<li>All three parts have equal binary values.</li>
-</ul>
-
-<p>If it is not possible, return <code>[-1, -1]</code>.</p>
-
-<p>Note that the entire part is used when considering what binary value it represents. For example, <code>[1,1,0]</code> represents <code>6</code> in decimal, not <code>3</code>. Also, leading zeros <strong>are allowed</strong>, so <code>[0,1,1]</code> and <code>[1,1]</code> represent the same value.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> arr = [1,0,1,0,1]
-<strong>Output:</strong> [0,3]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> arr = [1,1,0,1,1]
-<strong>Output:</strong> [-1,-1]
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> arr = [1,1,0,0,1]
-<strong>Output:</strong> [0,2]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= arr.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>arr[i]</code> is <code>0</code> or <code>1</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/three-equal-parts/three_equal_parts.go b/problems/three-equal-parts/three_equal_parts.go
deleted file mode 100644
index 040f36d97..000000000
--- a/problems/three-equal-parts/three_equal_parts.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem927
diff --git a/problems/three-equal-parts/three_equal_parts_test.go b/problems/three-equal-parts/three_equal_parts_test.go
deleted file mode 100644
index 040f36d97..000000000
--- a/problems/three-equal-parts/three_equal_parts_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem927
diff --git a/problems/throne-inheritance/README.md b/problems/throne-inheritance/README.md
deleted file mode 100644
index e33c7ee62..000000000
--- a/problems/throne-inheritance/README.md
+++ /dev/null
@@ -1,106 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-profit-of-operating-a-centennial-wheel "Maximum Profit of Operating a Centennial Wheel")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-number-of-achievable-transfer-requests "Maximum Number of Achievable Transfer Requests")
-
-## [1600. Throne Inheritance (Medium)](https://leetcode.com/problems/throne-inheritance "皇位继承顺序")
-
-<p>A kingdom consists of a king, his children, his grandchildren, and so on. Every once in a while, someone in the family dies or a child is born.</p>
-
-<p>The kingdom has a well-defined order of inheritance that consists of the king as the first member. Let&#39;s define the recursive function <code>Successor(x, curOrder)</code>, which given a person <code>x</code> and the inheritance order so far, returns who should be the next person after <code>x</code> in the order of inheritance.</p>
-
-<pre>
-Successor(x, curOrder):
-    if x has no children or all of x&#39;s children are in curOrder:
-        if x is the king return null
-        else return Successor(x&#39;s parent, curOrder)
-    else return x&#39;s oldest child who&#39;s not in curOrder
-</pre>
-
-<p>For example, assume we have a kingdom that consists of the king, his children Alice and Bob (Alice is older than Bob), and finally Alice&#39;s son Jack.</p>
-
-<ol>
-	<li>In the beginning, <code>curOrder</code> will be <code>[&quot;king&quot;]</code>.</li>
-	<li>Calling <code>Successor(king, curOrder)</code> will return Alice, so we append to <code>curOrder</code> to get <code>[&quot;king&quot;, &quot;Alice&quot;]</code>.</li>
-	<li>Calling <code>Successor(Alice, curOrder)</code> will return Jack, so we append to <code>curOrder</code> to get <code>[&quot;king&quot;, &quot;Alice&quot;, &quot;Jack&quot;]</code>.</li>
-	<li>Calling <code>Successor(Jack, curOrder)</code> will return Bob, so we append to <code>curOrder</code> to get <code>[&quot;king&quot;, &quot;Alice&quot;, &quot;Jack&quot;, &quot;Bob&quot;]</code>.</li>
-	<li>Calling <code>Successor(Bob, curOrder)</code> will return <code>null</code>. Thus the order of inheritance will be <code>[&quot;king&quot;, &quot;Alice&quot;, &quot;Jack&quot;, &quot;Bob&quot;]</code>.</li>
-</ol>
-
-<p>Using the above function, we can always obtain a unique order of inheritance.</p>
-
-<p>Implement the <code>ThroneInheritance</code> class:</p>
-
-<ul>
-	<li><code>ThroneInheritance(string kingName)</code> Initializes an object of the <code>ThroneInheritance</code> class. The name of the king is given as part of the constructor.</li>
-	<li><code>void birth(string parentName, string childName)</code> Indicates that <code>parentName</code> gave birth to <code>childName</code>.</li>
-	<li><code>void death(string name)</code> Indicates the death of <code>name</code>. The death of the person doesn&#39;t affect the <code>Successor</code> function nor the current inheritance order. You can treat it as just marking the person as dead.</li>
-	<li><code>string[] getInheritanceOrder()</code> Returns a list representing the current order of inheritance <strong>excluding</strong> dead people.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;ThroneInheritance&quot;, &quot;birth&quot;, &quot;birth&quot;, &quot;birth&quot;, &quot;birth&quot;, &quot;birth&quot;, &quot;birth&quot;, &quot;getInheritanceOrder&quot;, &quot;death&quot;, &quot;getInheritanceOrder&quot;]
-[[&quot;king&quot;], [&quot;king&quot;, &quot;andy&quot;], [&quot;king&quot;, &quot;bob&quot;], [&quot;king&quot;, &quot;catherine&quot;], [&quot;andy&quot;, &quot;matthew&quot;], [&quot;bob&quot;, &quot;alex&quot;], [&quot;bob&quot;, &quot;asha&quot;], [null], [&quot;bob&quot;], [null]]
-<strong>Output</strong>
-[null, null, null, null, null, null, null, [&quot;king&quot;, &quot;andy&quot;, &quot;matthew&quot;, &quot;bob&quot;, &quot;alex&quot;, &quot;asha&quot;, &quot;catherine&quot;], null, [&quot;king&quot;, &quot;andy&quot;, &quot;matthew&quot;, &quot;alex&quot;, &quot;asha&quot;, &quot;catherine&quot;]]
-
-<strong>Explanation</strong>
-ThroneInheritance t= new ThroneInheritance(&quot;king&quot;); // order: <strong>king</strong>
-t.birth(&quot;king&quot;, &quot;andy&quot;); // order: king &gt; <strong>andy</strong>
-t.birth(&quot;king&quot;, &quot;bob&quot;); // order: king &gt; andy &gt; <strong>bob</strong>
-t.birth(&quot;king&quot;, &quot;catherine&quot;); // order: king &gt; andy &gt; bob &gt; <strong>catherine</strong>
-t.birth(&quot;andy&quot;, &quot;matthew&quot;); // order: king &gt; andy &gt; <strong>matthew</strong> &gt; bob &gt; catherine
-t.birth(&quot;bob&quot;, &quot;alex&quot;); // order: king &gt; andy &gt; matthew &gt; bob &gt; <strong>alex</strong> &gt; catherine
-t.birth(&quot;bob&quot;, &quot;asha&quot;); // order: king &gt; andy &gt; matthew &gt; bob &gt; alex &gt; <strong>asha</strong> &gt; catherine
-t.getInheritanceOrder(); // return [&quot;king&quot;, &quot;andy&quot;, &quot;matthew&quot;, &quot;bob&quot;, &quot;alex&quot;, &quot;asha&quot;, &quot;catherine&quot;]
-t.death(&quot;bob&quot;); // order: king &gt; andy &gt; matthew &gt; <strong><s>bob</s></strong> &gt; alex &gt; asha &gt; catherine
-t.getInheritanceOrder(); // return [&quot;king&quot;, &quot;andy&quot;, &quot;matthew&quot;, &quot;alex&quot;, &quot;asha&quot;, &quot;catherine&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= kingName.length, parentName.length, childName.length, name.length &lt;= 15</code></li>
-	<li><code>kingName</code>, <code>parentName</code>, <code>childName</code>, and <code>name</code> consist of lowercase English letters only.</li>
-	<li>All arguments <code>childName</code> and <code>kingName</code> are <strong>distinct</strong>.</li>
-	<li>All <code>name</code> arguments of <code>death</code> will be passed to either the constructor or as <code>childName</code> to <code>birth</code> first.</li>
-	<li>For each call to&nbsp;<code>birth(parentName, childName)</code>, it is guaranteed that&nbsp;<code>parentName</code> is alive.</li>
-	<li>At most <code>10<sup>5</sup></code> calls will be made to <code>birth</code> and <code>death</code>.</li>
-	<li>At most <code>10</code> calls will be made to <code>getInheritanceOrder</code>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Design](../../tag/design/README.md)]
-
-### Similar Questions
-  1. [Operations on Tree](../operations-on-tree) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create a tree structure of the family.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Without deaths, the order of inheritance is simply a pre-order traversal of the tree.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Mark the dead family members tree nodes and don't include them in the final order.
-</details>
diff --git a/problems/tiling-a-rectangle-with-the-fewest-squares/README.md b/problems/tiling-a-rectangle-with-the-fewest-squares/README.md
deleted file mode 100644
index 1c2d357e2..000000000
--- a/problems/tiling-a-rectangle-with-the-fewest-squares/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-length-of-a-concatenated-string-with-unique-characters "Maximum Length of a Concatenated String with Unique Characters")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-comments-per-post "Number of Comments per Post")
-
-## [1240. Tiling a Rectangle with the Fewest Squares (Hard)](https://leetcode.com/problems/tiling-a-rectangle-with-the-fewest-squares "铺瓷砖")
-
-<p>Given a rectangle of size <code>n</code> x <code>m</code>, return <em>the minimum number of integer-sided squares that tile the rectangle</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/17/sample_11_1592.png" style="width: 154px; height: 106px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 2, m = 3
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> <code>3</code> squares are necessary to cover the rectangle.
-<code>2</code> (squares of <code>1x1</code>)
-<code>1</code> (square of <code>2x2</code>)</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/17/sample_22_1592.png" style="width: 224px; height: 126px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 5, m = 8
-<strong>Output:</strong> 5
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/17/sample_33_1592.png" style="width: 224px; height: 189px;" /></p>
-
-<pre>
-<strong>Input:</strong> n = 11, m = 13
-<strong>Output:</strong> 6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n, m &lt;= 13</code></li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you use backtracking to solve this problem ?.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Suppose you've placed a bunch of squares. Where is the natural spot to place the next square ?.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The maximum number of squares to be placed will be ≤ max(n,m).
-</details>
diff --git a/problems/time-based-key-value-store/README.md b/problems/time-based-key-value-store/README.md
deleted file mode 100644
index 559c1350b..000000000
--- a/problems/time-based-key-value-store/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-paths-iii "Unique Paths III")
-　　　　　　　　　　　　　　　　
-[Next >](../triples-with-bitwise-and-equal-to-zero "Triples with Bitwise AND Equal To Zero")
-
-## [981. Time Based Key-Value Store (Medium)](https://leetcode.com/problems/time-based-key-value-store "基于时间的键值存储")
-
-<p>Design a time-based key-value data structure that can store multiple values for the same key at different time stamps and retrieve the key&#39;s value at a certain timestamp.</p>
-
-<p>Implement the <code>TimeMap</code> class:</p>
-
-<ul>
-	<li><code>TimeMap()</code> Initializes the object of the data structure.</li>
-	<li><code>void set(String key, String value, int timestamp)</code> Stores the key <code>key</code> with the value <code>value </code>at the given time <code>timestamp</code>.</li>
-	<li><code>String get(String key, int timestamp)</code> Returns a value such that <code>set</code> was called previously, with <code>timestamp_prev &lt;= timestamp</code>. If there are multiple such values, it returns the value associated with the largest <code>timestamp_prev</code>. If there are no values, it returns <code>&quot;&quot;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;TimeMap&quot;, &quot;set&quot;, &quot;get&quot;, &quot;get&quot;, &quot;set&quot;, &quot;get&quot;, &quot;get&quot;]
-[[], [&quot;foo&quot;, &quot;bar&quot;, 1], [&quot;foo&quot;, 1], [&quot;foo&quot;, 3], [&quot;foo&quot;, &quot;bar2&quot;, 4], [&quot;foo&quot;, 4], [&quot;foo&quot;, 5]]
-<strong>Output</strong>
-[null, null, &quot;bar&quot;, &quot;bar&quot;, null, &quot;bar2&quot;, &quot;bar2&quot;]
-
-<strong>Explanation</strong>
-TimeMap timeMap = new TimeMap();
-timeMap.set(&quot;foo&quot;, &quot;bar&quot;, 1);  // store the key &quot;foo&quot; and value &quot;bar&quot; along with timestamp = 1.
-timeMap.get(&quot;foo&quot;, 1);         // return &quot;bar&quot;
-timeMap.get(&quot;foo&quot;, 3);         // return &quot;bar&quot;, since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 is &quot;bar&quot;.
-timeMap.set(&quot;foo&quot;, &quot;bar2&quot;, 4); // store the key &quot;foo&quot; and value &quot;bar2&quot; along with timestamp = 4.
-timeMap.get(&quot;foo&quot;, 4);         // return &quot;bar2&quot;
-timeMap.get(&quot;foo&quot;, 5);         // return &quot;bar2&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= key.length, value.length &lt;= 100</code></li>
-	<li><code>key</code> and <code>value</code> consist of lowercase English letters and digits.</li>
-	<li><code>1 &lt;= timestamp &lt;= 10<sup>7</sup></code></li>
-	<li>All the timestamps <code>timestamp</code> of <code>set</code> are strictly increasing.</li>
-	<li>At most <code>2 * 10<sup>5</sup></code> calls will be made to <code>set</code> and <code>get</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
diff --git a/problems/time-based-key-value-store/time_based_key_value_store.go b/problems/time-based-key-value-store/time_based_key_value_store.go
deleted file mode 100644
index 93b2a8775..000000000
--- a/problems/time-based-key-value-store/time_based_key_value_store.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem981
diff --git a/problems/time-needed-to-buy-tickets/README.md b/problems/time-needed-to-buy-tickets/README.md
deleted file mode 100644
index 5fd112421..000000000
--- a/problems/time-needed-to-buy-tickets/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../the-winner-university "The Winner University")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-nodes-in-even-length-groups "Reverse Nodes in Even Length Groups")
-
-## [2073. Time Needed to Buy Tickets (Easy)](https://leetcode.com/problems/time-needed-to-buy-tickets "买票需要的时间")
-
-<p>There are <code>n</code> people in a line queuing to buy tickets, where the <code>0<sup>th</sup></code> person is at the <strong>front</strong> of the line and the <code>(n - 1)<sup>th</sup></code> person is at the <strong>back</strong> of the line.</p>
-
-<p>You are given a <strong>0-indexed</strong> integer array <code>tickets</code> of length <code>n</code> where the number of tickets that the <code>i<sup>th</sup></code> person would like to buy is <code>tickets[i]</code>.</p>
-
-<p>Each person takes <strong>exactly 1 second</strong> to buy a ticket. A person can only buy <strong>1 ticket at a time</strong> and has to go back to <strong>the end</strong> of the line (which happens <strong>instantaneously</strong>) in order to buy more tickets. If a person does not have any tickets left to buy, the person will <strong>leave </strong>the line.</p>
-
-<p>Return <em>the <strong>time taken</strong> for the person at position </em><code>k</code><em>&nbsp;</em><strong><em>(0-indexed)</em>&nbsp;</strong><em>to finish buying tickets</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> tickets = [2,3,2], k = 2
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> 
-- In the first pass, everyone in the line buys a ticket and the line becomes [1, 2, 1].
-- In the second pass, everyone in the line buys a ticket and the line becomes [0, 1, 0].
-The person at&nbsp;position 2 has successfully bought 2 tickets and it took 3 + 3 = 6 seconds.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> tickets = [5,1,1,1], k = 0
-<strong>Output:</strong> 8
-<strong>Explanation:</strong>
-- In the first pass, everyone in the line buys a ticket and the line becomes [4, 0, 0, 0].
-- In the next 4 passes, only the person in position 0 is buying tickets.
-The person at&nbsp;position 0 has successfully bought 5 tickets and it took 4 + 1 + 1 + 1 + 1 = 8 seconds.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == tickets.length</code></li>
-	<li><code>1 &lt;= n &lt;= 100</code></li>
-	<li><code>1 &lt;= tickets[i] &lt;= 100</code></li>
-	<li><code>0 &lt;= k &lt; n</code></li>
-</ul>
-
-### Related Topics
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Loop through the line of people and decrement the number of tickets for each to buy one at a time as if simulating the line moving forward. Keep track of how many tickets have been sold up until person k has no more tickets to buy.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Remember that those who have no more tickets to buy will leave the line.
-</details>
diff --git a/problems/time-needed-to-inform-all-employees/README.md b/problems/time-needed-to-inform-all-employees/README.md
deleted file mode 100644
index af158e624..000000000
--- a/problems/time-needed-to-inform-all-employees/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-times-binary-string-is-prefix-aligned "Number of Times Binary String Is Prefix-Aligned")
-　　　　　　　　　　　　　　　　
-[Next >](../frog-position-after-t-seconds "Frog Position After T Seconds")
-
-## [1376. Time Needed to Inform All Employees (Medium)](https://leetcode.com/problems/time-needed-to-inform-all-employees "通知所有员工所需的时间")
-
-<p>A company has <code>n</code> employees with a unique ID for each employee from <code>0</code> to <code>n - 1</code>. The head of the company is the one with <code>headID</code>.</p>
-
-<p>Each employee has one direct manager given in the <code>manager</code> array where <code>manager[i]</code> is the direct manager of the <code>i-th</code> employee, <code>manager[headID] = -1</code>. Also, it is guaranteed that the subordination relationships have a tree structure.</p>
-
-<p>The head of the company wants to inform all the company employees of an urgent piece of news. He will inform his direct subordinates, and they will inform their subordinates, and so on until all employees know about the urgent news.</p>
-
-<p>The <code>i-th</code> employee needs <code>informTime[i]</code> minutes to inform all of his direct subordinates (i.e., After informTime[i] minutes, all his direct subordinates can start spreading the news).</p>
-
-<p>Return <em>the number of minutes</em> needed to inform all the employees about the urgent news.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1, headID = 0, manager = [-1], informTime = [0]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The head of the company is the only employee in the company.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/02/27/graph.png" style="width: 404px; height: 174px;" />
-<pre>
-<strong>Input:</strong> n = 6, headID = 2, manager = [2,2,-1,2,2,2], informTime = [0,0,1,0,0,0]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The head of the company with id = 2 is the direct manager of all the employees in the company and needs 1 minute to inform them all.
-The tree structure of the employees in the company is shown.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= headID &lt; n</code></li>
-	<li><code>manager.length == n</code></li>
-	<li><code>0 &lt;= manager[i] &lt; n</code></li>
-	<li><code>manager[headID] == -1</code></li>
-	<li><code>informTime.length == n</code></li>
-	<li><code>0 &lt;= informTime[i] &lt;= 1000</code></li>
-	<li><code>informTime[i] == 0</code> if employee <code>i</code> has no subordinates.</li>
-	<li>It is <strong>guaranteed</strong> that all the employees can be informed.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Maximum Depth of Binary Tree](../maximum-depth-of-binary-tree) (Easy)
-  1. [Binary Tree Maximum Path Sum](../binary-tree-maximum-path-sum) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The company can be represented as a tree, headID is always the root.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Store for each node the time needed to be informed of the news.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Answer is the max time a leaf node needs to be informed.
-</details>
diff --git a/problems/to-lower-case/README.md b/problems/to-lower-case/README.md
deleted file mode 100644
index 5b2bc0157..000000000
--- a/problems/to-lower-case/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../insert-into-a-sorted-circular-linked-list "Insert into a Sorted Circular Linked List")
-　　　　　　　　　　　　　　　　
-[Next >](../random-pick-with-blacklist "Random Pick with Blacklist")
-
-## [709. To Lower Case (Easy)](https://leetcode.com/problems/to-lower-case "转换成小写字母")
-
-<p>Given a string <code>s</code>, return <em>the string after replacing every uppercase letter with the same lowercase letter</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;Hello&quot;
-<strong>Output:</strong> &quot;hello&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;here&quot;
-<strong>Output:</strong> &quot;here&quot;
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;LOVELY&quot;
-<strong>Output:</strong> &quot;lovely&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s</code> consists of printable ASCII characters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Most languages support lowercase conversion for a string data type. However, that is certainly not the purpose of the problem. Think about how the implementation of the lowercase function call can be done easily.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-<b>Think ASCII!</b>
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Think about the different capital letters and their ASCII codes and how that relates to their lowercase counterparts. Does there seem to be any pattern there? Any mathematical relationship that we can use?
-</details>
diff --git a/problems/to-lower-case/to_lower_case.go b/problems/to-lower-case/to_lower_case.go
deleted file mode 100644
index 780016c2b..000000000
--- a/problems/to-lower-case/to_lower_case.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package problem709
-
-import "strings"
-
-func toLowerCase(str string) string {
-	return strings.ToLower(str)
-}
diff --git a/problems/to-lower-case/to_lower_case_test.go b/problems/to-lower-case/to_lower_case_test.go
deleted file mode 100644
index 6be8dcd93..000000000
--- a/problems/to-lower-case/to_lower_case_test.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem709
-
-import "testing"
-
-func TestToLowerCase(t *testing.T) {
-	tests := map[string]string{
-		"Hello":  "hello",
-		"here":   "here",
-		"LOVELY": "lovely",
-		"aweSee": "awesee",
-	}
-
-	for in, want := range tests {
-		got := toLowerCase(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
diff --git a/problems/toeplitz-matrix/README.md b/problems/toeplitz-matrix/README.md
deleted file mode 100644
index c9dffec1b..000000000
--- a/problems/toeplitz-matrix/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../couples-holding-hands "Couples Holding Hands")
-　　　　　　　　　　　　　　　　
-[Next >](../reorganize-string "Reorganize String")
-
-## [766. Toeplitz Matrix (Easy)](https://leetcode.com/problems/toeplitz-matrix "托普利茨矩阵")
-
-<p>Given an <code>m x n</code> <code>matrix</code>, return&nbsp;<em><code>true</code>&nbsp;if the matrix is Toeplitz. Otherwise, return <code>false</code>.</em></p>
-
-<p>A matrix is <strong>Toeplitz</strong> if every diagonal from top-left to bottom-right has the same elements.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/04/ex1.jpg" style="width: 322px; height: 242px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,2,3,4],[5,1,2,3],[9,5,1,2]]
-<strong>Output:</strong> true
-<strong>Explanation:</strong>
-In the above grid, the&nbsp;diagonals are:
-&quot;[9]&quot;, &quot;[5, 5]&quot;, &quot;[1, 1, 1]&quot;, &quot;[2, 2, 2]&quot;, &quot;[3, 3]&quot;, &quot;[4]&quot;.
-In each diagonal all elements are the same, so the answer is True.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/04/ex2.jpg" style="width: 162px; height: 162px;" />
-<pre>
-<strong>Input:</strong> matrix = [[1,2],[2,2]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong>
-The diagonal &quot;[1, 2]&quot; has different elements.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 20</code></li>
-	<li><code>0 &lt;= matrix[i][j] &lt;= 99</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong></p>
-
-<ul>
-	<li>What if the <code>matrix</code> is stored on disk, and the memory is limited such that you can only load at most one row of the matrix into the memory at once?</li>
-	<li>What if the <code>matrix</code> is so large that you can only load up a partial row into the memory at once?</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Valid Word Square](../valid-word-square) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Check whether each value is equal to the value of it's top-left neighbor.
-</details>
diff --git a/problems/toeplitz-matrix/toeplitz_matrix.go b/problems/toeplitz-matrix/toeplitz_matrix.go
deleted file mode 100644
index 2a4bec580..000000000
--- a/problems/toeplitz-matrix/toeplitz_matrix.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem766
-
-func isToeplitzMatrix(matrix [][]int) bool {
-	for i, row := range matrix[1:] {
-		for j, v := range row[1:] {
-			if v != matrix[i][j] {
-				return false
-			}
-		}
-	}
-	return true
-}
diff --git a/problems/toeplitz-matrix/toeplitz_matrix_test.go b/problems/toeplitz-matrix/toeplitz_matrix_test.go
deleted file mode 100644
index df54e8b12..000000000
--- a/problems/toeplitz-matrix/toeplitz_matrix_test.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package problem766
-
-import "testing"
-
-type testType struct {
-	in   [][]int
-	want bool
-}
-
-func TestIsToeplitzMatrix(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{1, 2, 3, 4},
-				{5, 1, 2, 3},
-				{9, 5, 1, 2},
-			},
-			want: true,
-		},
-		{
-			in: [][]int{
-				{1, 2},
-				{2, 2},
-			},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isToeplitzMatrix(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/top-k-frequent-elements/README.md b/problems/top-k-frequent-elements/README.md
deleted file mode 100644
index ac17ea0c6..000000000
--- a/problems/top-k-frequent-elements/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../moving-average-from-data-stream "Moving Average from Data Stream")
-　　　　　　　　　　　　　　　　
-[Next >](../design-tic-tac-toe "Design Tic-Tac-Toe")
-
-## [347. Top K Frequent Elements (Medium)](https://leetcode.com/problems/top-k-frequent-elements "前 K 个高频元素")
-
-<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the</em> <code>k</code> <em>most frequent elements</em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> nums = [1,1,1,2,2,3], k = 2
-<strong>Output:</strong> [1,2]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> nums = [1], k = 1
-<strong>Output:</strong> [1]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>k</code> is in the range <code>[1, the number of unique elements in the array]</code>.</li>
-	<li>It is <strong>guaranteed</strong> that the answer is <strong>unique</strong>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Your algorithm&#39;s time complexity must be better than <code>O(n log n)</code>, where n is the array&#39;s size.</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Bucket Sort](../../tag/bucket-sort/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Quickselect](../../tag/quickselect/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Word Frequency](../word-frequency) (Medium)
-  1. [Kth Largest Element in an Array](../kth-largest-element-in-an-array) (Medium)
-  1. [Sort Characters By Frequency](../sort-characters-by-frequency) (Medium)
-  1. [Split Array into Consecutive Subsequences](../split-array-into-consecutive-subsequences) (Medium)
-  1. [Top K Frequent Words](../top-k-frequent-words) (Medium)
-  1. [K Closest Points to Origin](../k-closest-points-to-origin) (Medium)
diff --git a/problems/top-k-frequent-elements/top_k_frequent_elements.go b/problems/top-k-frequent-elements/top_k_frequent_elements.go
deleted file mode 100644
index 4f2b3a269..000000000
--- a/problems/top-k-frequent-elements/top_k_frequent_elements.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem347
diff --git a/problems/top-k-frequent-elements/top_k_frequent_elements_test.go b/problems/top-k-frequent-elements/top_k_frequent_elements_test.go
deleted file mode 100644
index 4f2b3a269..000000000
--- a/problems/top-k-frequent-elements/top_k_frequent_elements_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem347
diff --git a/problems/top-k-frequent-words/README.md b/problems/top-k-frequent-words/README.md
deleted file mode 100644
index 333a0533c..000000000
--- a/problems/top-k-frequent-words/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stickers-to-spell-word "Stickers to Spell Word")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-number-with-alternating-bits "Binary Number with Alternating Bits")
-
-## [692. Top K Frequent Words (Medium)](https://leetcode.com/problems/top-k-frequent-words "前K个高频单词")
-
-<p>Given an array of strings <code>words</code> and an integer <code>k</code>, return <em>the </em><code>k</code><em> most frequent strings</em>.</p>
-
-<p>Return the answer <strong>sorted</strong> by <strong>the frequency</strong> from highest to lowest. Sort the words with the same frequency by their <strong>lexicographical order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;i&quot;,&quot;love&quot;,&quot;leetcode&quot;,&quot;i&quot;,&quot;love&quot;,&quot;coding&quot;], k = 2
-<strong>Output:</strong> [&quot;i&quot;,&quot;love&quot;]
-<strong>Explanation:</strong> &quot;i&quot; and &quot;love&quot; are the two most frequent words.
-Note that &quot;i&quot; comes before &quot;love&quot; due to a lower alphabetical order.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;the&quot;,&quot;day&quot;,&quot;is&quot;,&quot;sunny&quot;,&quot;the&quot;,&quot;the&quot;,&quot;the&quot;,&quot;sunny&quot;,&quot;is&quot;,&quot;is&quot;], k = 4
-<strong>Output:</strong> [&quot;the&quot;,&quot;is&quot;,&quot;sunny&quot;,&quot;day&quot;]
-<strong>Explanation:</strong> &quot;the&quot;, &quot;is&quot;, &quot;sunny&quot; and &quot;day&quot; are the four most frequent words, with the number of occurrence being 4, 3, 2 and 1 respectively.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 500</code></li>
-	<li><code>1 &lt;= words[i] &lt;= 10</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters.</li>
-	<li><code>k</code> is in the range <code>[1, The number of <strong>unique</strong> words[i]]</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow-up:</strong> Could you solve it in <code>O(n log(k))</code> time and <code>O(n)</code> extra space?</p>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Bucket Sort](../../tag/bucket-sort/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Top K Frequent Elements](../top-k-frequent-elements) (Medium)
-  1. [K Closest Points to Origin](../k-closest-points-to-origin) (Medium)
diff --git a/problems/top-k-frequent-words/top_k_frequent_words.go b/problems/top-k-frequent-words/top_k_frequent_words.go
deleted file mode 100644
index 27107370f..000000000
--- a/problems/top-k-frequent-words/top_k_frequent_words.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem692
diff --git a/problems/top-k-frequent-words/top_k_frequent_words_test.go b/problems/top-k-frequent-words/top_k_frequent_words_test.go
deleted file mode 100644
index 27107370f..000000000
--- a/problems/top-k-frequent-words/top_k_frequent_words_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem692
diff --git a/problems/top-travellers/README.md b/problems/top-travellers/README.md
deleted file mode 100644
index 8e18a5b3a..000000000
--- a/problems/top-travellers/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stone-game-iii "Stone Game III")
-　　　　　　　　　　　　　　　　
-[Next >](../string-matching-in-an-array "String Matching in an Array")
-
-## [1407. Top Travellers (Easy)](https://leetcode.com/problems/top-travellers "排名靠前的旅行者")
-
-<p>Table: <code>Users</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| name          | varchar |
-+---------------+---------+
-id is the primary key for this table.
-name is the name of the user.
-</pre>
- 
-<p>Table: <code>Rides</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| id            | int     |
-| user_id       | int     |
-| distance      | int     |
-+---------------+---------+
-id is the primary key for this table.
-city_id is the id of the city who bought the product "product_name".
-</pre>
- 
-Write an SQL query to report the distance travelled by each user.
-
-Return the result table ordered by travelled_distance in descending order, if two or more users travelled the same distance, order them by their name in ascending order.
-
-The query result format is in the following example.
-<pre>
-Users table:
-+------+-----------+
-| id   | name      |
-+------+-----------+
-| 1    | Alice     |
-| 2    | Bob       |
-| 3    | Alex      |
-| 4    | Donald    |
-| 7    | Lee       |
-| 13   | Jonathan  |
-| 19   | Elvis     |
-+------+-----------+
-
-Rides table:
-+------+----------+----------+
-| id   | user_id  | distance |
-+------+----------+----------+
-| 1    | 1        | 120      |
-| 2    | 2        | 317      |
-| 3    | 3        | 222      |
-| 4    | 7        | 100      |
-| 5    | 13       | 312      |
-| 6    | 19       | 50       |
-| 7    | 7        | 120      |
-| 8    | 19       | 400      |
-| 9    | 7        | 230      |
-+------+----------+----------+
-
-Result table:
-+----------+--------------------+
-| name     | travelled_distance |
-+----------+--------------------+
-| Elvis    | 450                |
-| Lee      | 450                |
-| Bob      | 317                |
-| Jonathan | 312                |
-| Alex     | 222                |
-| Alice    | 120                |
-| Donald   | 0                  |
-+----------+--------------------+
-Elvis and Lee travelled 450 miles, Elvis is the top traveller as his name is alphabetically smaller than Lee.
-Bob, Jonathan, Alex and Alice have only one ride and we just order them by the total distances of the ride.
-Donald didn't have any rides, the distance travelled by him is 0.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/top-travellers/mysql_schemas.sql b/problems/top-travellers/mysql_schemas.sql
deleted file mode 100644
index 4d1dbe7da..000000000
--- a/problems/top-travellers/mysql_schemas.sql
+++ /dev/null
@@ -1,20 +0,0 @@
-Create Table If Not Exists Users (id int, name varchar(30));
-Create Table If Not Exists Rides (id int, user_id int, distance int);
-Truncate table Users;
-insert into Users (id, name) values ('1', 'Alice');
-insert into Users (id, name) values ('2', 'Bob');
-insert into Users (id, name) values ('3', 'Alex');
-insert into Users (id, name) values ('4', 'Donald');
-insert into Users (id, name) values ('7', 'Lee');
-insert into Users (id, name) values ('13', 'Jonathan');
-insert into Users (id, name) values ('19', 'Elvis');
-Truncate table Rides;
-insert into Rides (id, user_id, distance) values ('1', '1', '120');
-insert into Rides (id, user_id, distance) values ('2', '2', '317');
-insert into Rides (id, user_id, distance) values ('3', '3', '222');
-insert into Rides (id, user_id, distance) values ('4', '7', '100');
-insert into Rides (id, user_id, distance) values ('5', '13', '312');
-insert into Rides (id, user_id, distance) values ('6', '19', '50');
-insert into Rides (id, user_id, distance) values ('7', '7', '120');
-insert into Rides (id, user_id, distance) values ('8', '19', '400');
-insert into Rides (id, user_id, distance) values ('9', '7', '230');
diff --git a/problems/toss-strange-coins/README.md b/problems/toss-strange-coins/README.md
deleted file mode 100644
index 045ee166b..000000000
--- a/problems/toss-strange-coins/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../meeting-scheduler "Meeting Scheduler")
-　　　　　　　　　　　　　　　　
-[Next >](../divide-chocolate "Divide Chocolate")
-
-## [1230. Toss Strange Coins (Medium)](https://leetcode.com/problems/toss-strange-coins "抛掷硬币")
-
-<p>You have some coins.&nbsp; The <code>i</code>-th&nbsp;coin has a probability&nbsp;<code>prob[i]</code> of facing heads when tossed.</p>
-
-<p>Return the probability that the number of coins facing heads equals <code>target</code> if you toss every coin exactly once.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> prob = [0.4], target = 1
-<strong>Output:</strong> 0.40000
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> prob = [0.5,0.5,0.5,0.5,0.5], target = 0
-<strong>Output:</strong> 0.03125
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= prob.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= prob[i] &lt;= 1</code></li>
-	<li><code>0 &lt;= target&nbsp;</code><code>&lt;= prob.length</code></li>
-	<li>Answers will be accepted as correct if they are within <code>10^-5</code> of the correct answer.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Probability and Statistics](../../tag/probability-and-statistics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What about solving the problem with DP?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Use DP with two states dp[pos][cnt], where pos represents the pos-th coin and cnt is the number of heads seen so far.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-You can do the transitions with a little bit math.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-For the base case, when pos == n return (cnt == target) to filter out the invalid scenarios.
-</details>
diff --git a/problems/total-hamming-distance/README.md b/problems/total-hamming-distance/README.md
deleted file mode 100644
index 6ec41c314..000000000
--- a/problems/total-hamming-distance/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-complement "Number Complement")
-　　　　　　　　　　　　　　　　
-[Next >](../generate-random-point-in-a-circle "Generate Random Point in a Circle")
-
-## [477. Total Hamming Distance (Medium)](https://leetcode.com/problems/total-hamming-distance "汉明距离总和")
-
-<p>The <a href="https://en.wikipedia.org/wiki/Hamming_distance" target="_blank">Hamming distance</a> between two integers is the number of positions at which the corresponding bits are different.</p>
-
-<p>Given an integer array <code>nums</code>, return <em>the sum of <strong>Hamming distances</strong> between all the pairs of the integers in</em> <code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,14,2]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> In binary representation, the 4 is 0100, 14 is 1110, and 2 is 0010 (just
-showing the four bits relevant in this case).
-The answer will be:
-HammingDistance(4, 14) + HammingDistance(4, 2) + HammingDistance(14, 2) = 2 + 2 + 2 = 6.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,14,4]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li>The answer for the given input will fit in a <strong>32-bit</strong> integer.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Similar Questions
-  1. [Hamming Distance](../hamming-distance) (Easy)
diff --git a/problems/total-hamming-distance/total_hamming_distance.go b/problems/total-hamming-distance/total_hamming_distance.go
deleted file mode 100644
index d6463b474..000000000
--- a/problems/total-hamming-distance/total_hamming_distance.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem477
diff --git a/problems/total-hamming-distance/total_hamming_distance_test.go b/problems/total-hamming-distance/total_hamming_distance_test.go
deleted file mode 100644
index d6463b474..000000000
--- a/problems/total-hamming-distance/total_hamming_distance_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem477
diff --git a/problems/total-sales-amount-by-year/README.md b/problems/total-sales-amount-by-year/README.md
deleted file mode 100644
index f2a0dc254..000000000
--- a/problems/total-sales-amount-by-year/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-performance-of-a-team "Maximum Performance of a Team")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-distance-value-between-two-arrays "Find the Distance Value Between Two Arrays")
-
-## [1384. Total Sales Amount by Year (Hard)](https://leetcode.com/problems/total-sales-amount-by-year "按年度列出销售总额")
-
-<p>Table: <code>Product</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| product_id    | int     |
-| product_name  | varchar |
-+---------------+---------+
-product_id is the primary key for this table.
-product_name is the name of the product.
-</pre>
- 
-<p>Table: <code>Sales</code></p>
-<pre>
-+---------------------+---------+
-| Column Name         | Type    |
-+---------------------+---------+
-| product_id          | int     |
-| period_start        | varchar |
-| period_end          | date    |
-| average_daily_sales | int     |
-+---------------------+---------+
-product_id is the primary key for this table. 
-period_start and period_end indicates the start and end date for sales period, both dates are inclusive.
-The average_daily_sales column holds the average daily sales amount of the items for the period.
-</pre>
-
-Write an SQL query to report the Total sales amount of each item for each year, with corresponding product name, product_id, product_name and report_year.
-
-Dates of the sales years are between 2018 to 2020. Return the result table ordered by product_id and report_year.
-
-The query result format is in the following example:
-
-<pre>
-Product table:
-+------------+--------------+
-| product_id | product_name |
-+------------+--------------+
-| 1          | LC Phone     |
-| 2          | LC T-Shirt   |
-| 3          | LC Keychain  |
-+------------+--------------+
-
-Sales table:
-+------------+--------------+-------------+---------------------+
-| product_id | period_start | period_end  | average_daily_sales |
-+------------+--------------+-------------+---------------------+
-| 1          | 2019-01-25   | 2019-02-28  | 100                 |
-| 2          | 2018-12-01   | 2020-01-01  | 10                  |
-| 3          | 2019-12-01   | 2020-01-31  | 1                   |
-+------------+--------------+-------------+---------------------+
-
-Result table:
-+------------+--------------+-------------+--------------+
-| product_id | product_name | report_year | total_amount |
-+------------+--------------+-------------+--------------+
-| 1          | LC Phone     |    2019     | 3500         |
-| 2          | LC T-Shirt   |    2018     | 310          |
-| 2          | LC T-Shirt   |    2019     | 3650         |
-| 2          | LC T-Shirt   |    2020     | 10           |
-| 3          | LC Keychain  |    2019     | 31           |
-| 3          | LC Keychain  |    2020     | 31           |
-+------------+--------------+-------------+--------------+
-LC Phone was sold for the period of 2019-01-25 to 2019-02-28, and there are 35 days for this period. Total amount 35*100 = 3500. 
-LC T-shirt was sold for the period of 2018-12-01 to 2020-01-01, and there are 31, 365, 1 days for years 2018, 2019 and 2020 respectively.
-LC Keychain was sold for the period of 2019-12-01 to 2020-01-31, and there are 31, 31 days for years 2019 and 2020 respectively.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/total-sales-amount-by-year/mysql_schemas.sql b/problems/total-sales-amount-by-year/mysql_schemas.sql
deleted file mode 100644
index 28c6d0ba1..000000000
--- a/problems/total-sales-amount-by-year/mysql_schemas.sql
+++ /dev/null
@@ -1,10 +0,0 @@
-Create table If Not Exists Product (product_id int, product_name varchar(30));
-Create table If Not Exists Sales (product_id varchar(30), period_start date, period_end date, average_daily_sales int);
-Truncate table Product;
-insert into Product (product_id, product_name) values ('1', 'LC Phone ');
-insert into Product (product_id, product_name) values ('2', 'LC T-Shirt');
-insert into Product (product_id, product_name) values ('3', 'LC Keychain');
-Truncate table Sales;
-insert into Sales (product_id, period_start, period_end, average_daily_sales) values ('1', '2019-01-25', '2019-02-28', '100');
-insert into Sales (product_id, period_start, period_end, average_daily_sales) values ('2', '2018-12-01', '2020-01-01', '10');
-insert into Sales (product_id, period_start, period_end, average_daily_sales) values ('3', '2019-12-01', '2020-01-31', '1');
diff --git a/problems/tournament-winners/README.md b/problems/tournament-winners/README.md
deleted file mode 100644
index 0453627de..000000000
--- a/problems/tournament-winners/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../monthly-transactions-i "Monthly Transactions I")
-　　　　　　　　　　　　　　　　
-[Next >](../fizz-buzz-multithreaded "Fizz Buzz Multithreaded")
-
-## [1194. Tournament Winners (Hard)](https://leetcode.com/problems/tournament-winners "锦标赛优胜者")
-
-<p>Table:&nbsp;<code>Players</code></p>
-
-<pre>
-+-------------+-------+
-| Column Name | Type  |
-+-------------+-------+
-| player_id   | int   |
-| group_id    | int   |
-+-------------+-------+
-player_id is the primary key of this table.
-Each row of this table indicates the group of each player.
-</pre>
-
-<p>Table:&nbsp;<code>Matches</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| match_id      | int     |
-| first_player  | int     |
-| second_player | int     | 
-| first_score   | int     |
-| second_score  | int     |
-+---------------+---------+
-match_id is the primary key of this table.
-Each row is a record of a match, first_player and second_player contain the player_id of each match.
-first_score and second_score contain the number of points of the first_player and second_player respectively.
-You may assume that, in each match, players belongs to the same group.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>The winner in each group is the player who scored the maximum total points within the group.&nbsp;In the case of a tie, the <strong>lowest</strong> player_id&nbsp;wins.</p>
-
-<p>Write an SQL query to find the winner in each group.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-<code>Players </code>table:
-+-----------+------------+
-| player_id | group_id   |
-+-----------+------------+
-| 15        | 1          |
-| 25        | 1          |
-| 30        | 1          |
-| 45        | 1          |
-| 10        | 2          |
-| 35        | 2          |
-| 50        | 2          |
-| 20        | 3          |
-| 40        | 3          |
-+-----------+------------+
-
-<code>Matches </code>table:
-+------------+--------------+---------------+-------------+--------------+
-| match_id   | first_player | second_player | first_score | second_score |
-+------------+--------------+---------------+-------------+--------------+
-| 1          | 15           | 45            | 3           | 0            |
-| 2          | 30           | 25            | 1           | 2            |
-| 3          | 30           | 15            | 2           | 0            |
-| 4          | 40           | 20            | 5           | 2            |
-| 5          | 35           | 50            | 1           | 1            |
-+------------+--------------+---------------+-------------+--------------+
-
-Result table:
-+-----------+------------+
-| group_id  | player_id  |
-+-----------+------------+ 
-| 1         | 15         |
-| 2         | 35         |
-| 3         | 40         |
-+-----------+------------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/tournament-winners/mysql_schemas.sql b/problems/tournament-winners/mysql_schemas.sql
deleted file mode 100644
index ab978981b..000000000
--- a/problems/tournament-winners/mysql_schemas.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-Create table If Not Exists Players (player_id int, group_id int);
-Create table If Not Exists Matches (match_id int, first_player int, second_player int, first_score int, second_score int)
-;
-Truncate table Players;
-insert into Players (player_id, group_id) values ('10', '2');
-insert into Players (player_id, group_id) values ('15', '1');
-insert into Players (player_id, group_id) values ('20', '3');
-insert into Players (player_id, group_id) values ('25', '1');
-insert into Players (player_id, group_id) values ('30', '1');
-insert into Players (player_id, group_id) values ('35', '2');
-insert into Players (player_id, group_id) values ('40', '3');
-insert into Players (player_id, group_id) values ('45', '1');
-insert into Players (player_id, group_id) values ('50', '2');
-Truncate table Matches;
-insert into Matches (match_id, first_player, second_player, first_score, second_score) values ('1', '15', '45', '3', '0');
-insert into Matches (match_id, first_player, second_player, first_score, second_score) values ('2', '30', '25', '1', '2');
-insert into Matches (match_id, first_player, second_player, first_score, second_score) values ('3', '30', '15', '2', '0');
-insert into Matches (match_id, first_player, second_player, first_score, second_score) values ('4', '40', '20', '5', '2');
-insert into Matches (match_id, first_player, second_player, first_score, second_score) values ('5', '35', '50', '1', '1');
diff --git a/problems/traffic-light-controlled-intersection/README.md b/problems/traffic-light-controlled-intersection/README.md
deleted file mode 100644
index 818d55bd4..000000000
--- a/problems/traffic-light-controlled-intersection/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../palindrome-partitioning-iii "Palindrome Partitioning III")
-　　　　　　　　　　　　　　　　
-[Next >](../students-and-examinations "Students and Examinations")
-
-## [1279. Traffic Light Controlled Intersection (Easy)](https://leetcode.com/problems/traffic-light-controlled-intersection "红绿灯路口")
-
-There is an intersection of two roads. First road is road A where cars travel from North to South in direction 1 and from South to North in direction 2. Second road is road B where cars travel from West to East in direction 3 and from East to West in direction 4.
-
-There is a traffic light located on each road before the intersection. A traffic light can either be green or red.
-
-1. Green means cars can cross the intersection in both directions of the road.
-- Red means cars in both directions cannot cross the intersection and must wait until the light turns green.
-
-The traffic lights cannot be green on both roads at the same time. That means when the light is green on road A, it is red on road B and when the light is green on road B, it is red on road A.
-
-Initially, the traffic light is green on road A and red on road B. When the light is green on one road, all cars can cross the intersection in both directions until the light becomes green on the other road. No two cars traveling on different roads should cross at the same time.
-
-Design a deadlock-free traffic light controlled system at this intersection.
-
-Implement the function void carArrived(carId, roadId, direction, turnGreen, crossCar) where:
-
-- carId is the id of the car that arrived.
-- roadId is the id of the road that the car travels on.
-- direction is the direction of the car.
-- turnGreen is a function you can call to turn the traffic light to green on the current road.
-- crossCar is a function you can call to let the current car cross the intersection.
-
-Your answer is considered correct if it avoids cars deadlock in the intersection. Turning the light green on a road when it was already green is considered a wrong answer.
- 
-<p><b>Example 1:</b></p>
-<pre>
-Input: cars = [1,3,5,2,4], directions = [2,1,2,4,3], arrivalTimes = [10,20,30,40,50]
-Output: [
-"Car 1 Has Passed Road A In Direction 2",    // Traffic light on road A is green, car 1 can cross the intersection.
-"Car 3 Has Passed Road A In Direction 1",    // Car 3 crosses the intersection as the light is still green.
-"Car 5 Has Passed Road A In Direction 2",    // Car 5 crosses the intersection as the light is still green.
-"Traffic Light On Road B Is Green",          // Car 2 requests green light for road B.
-"Car 2 Has Passed Road B In Direction 4",    // Car 2 crosses as the light is green on road B now.
-"Car 4 Has Passed Road B In Direction 3"     // Car 4 crosses the intersection as the light is still green.
-]
-</pre>
-
-<p><b>Example 2:</b></p>
-<pre>
-Input: cars = [1,2,3,4,5], directions = [2,4,3,3,1], arrivalTimes = [10,20,30,40,40]
-Output: [
-"Car 1 Has Passed Road A In Direction 2",    // Traffic light on road A is green, car 1 can cross the intersection.
-"Traffic Light On Road B Is Green",          // Car 2 requests green light for road B.
-"Car 2 Has Passed Road B In Direction 4",    // Car 2 crosses as the light is green on road B now.
-"Car 3 Has Passed Road B In Direction 3",    // Car 3 crosses as the light is green on road B now.
-"Traffic Light On Road A Is Green",          // Car 5 requests green light for road A.
-"Car 5 Has Passed Road A In Direction 1",    // Car 5 crosses as the light is green on road A now.
-"Traffic Light On Road B Is Green",          // Car 4 requests green light for road B. Car 4 blocked until car 5 crosses and then traffic light is green on road B.
-"Car 4 Has Passed Road B In Direction 3"     // Car 4 crosses as the light is green on road B now.
-]
-Explanation: This is a dead-lock free scenario. Note that the scenario when car 4 crosses before turning light into green on road A and allowing car 5 to pass is also correct and Accepted scenario.
-</pre>
- 
-Constraints:
-
-- 1 <= cars.length <= 20
-- cars.length = directions.length
-- cars.length = arrivalTimes.length
-- All values of cars are unique
-- 1 <= directions[i] <= 4
-- arrivalTimes is non-decreasing
-
-### Related Topics
-  [[Concurrency](../../tag/concurrency/README.md)]
diff --git a/problems/transform-to-chessboard/README.md b/problems/transform-to-chessboard/README.md
deleted file mode 100644
index 4230baade..000000000
--- a/problems/transform-to-chessboard/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rabbits-in-forest "Rabbits in Forest")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-distance-between-bst-nodes "Minimum Distance Between BST Nodes")
-
-## [782. Transform to Chessboard (Hard)](https://leetcode.com/problems/transform-to-chessboard "变为棋盘")
-
-<p>You are given an <code>n x n</code> binary grid <code>board</code>. In each move, you can swap any two rows with each other, or any two columns with each other.</p>
-
-<p>Return <em>the minimum number of moves to transform the board into a <strong>chessboard board</strong></em>. If the task is impossible, return <code>-1</code>.</p>
-
-<p>A <strong>chessboard board</strong> is a board where no <code>0</code>&#39;s and no <code>1</code>&#39;s are 4-directionally adjacent.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/chessboard1-grid.jpg" style="width: 500px; height: 145px;" />
-<pre>
-<strong>Input:</strong> board = [[0,1,1,0],[0,1,1,0],[1,0,0,1],[1,0,0,1]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> One potential sequence of moves is shown.
-The first move swaps the first and second column.
-The second move swaps the second and third row.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/chessboard2-grid.jpg" style="width: 164px; height: 165px;" />
-<pre>
-<strong>Input:</strong> board = [[0,1],[1,0]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> Also note that the board with 0 in the top left corner, is also a valid chessboard.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/chessboard3-grid.jpg" style="width: 164px; height: 165px;" />
-<pre>
-<strong>Input:</strong> board = [[1,0],[1,0]]
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> No matter what sequence of moves you make, you cannot end with a valid chessboard.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == board.length</code></li>
-	<li><code>n == board[i].length</code></li>
-	<li><code>2 &lt;= n &lt;= 30</code></li>
-	<li><code>board[i][j]</code> is either&nbsp;<code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
diff --git a/problems/transform-to-chessboard/transform_to_chessboard.go b/problems/transform-to-chessboard/transform_to_chessboard.go
deleted file mode 100644
index e8a1981ef..000000000
--- a/problems/transform-to-chessboard/transform_to_chessboard.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem782
diff --git a/problems/transform-to-chessboard/transform_to_chessboard_test.go b/problems/transform-to-chessboard/transform_to_chessboard_test.go
deleted file mode 100644
index e8a1981ef..000000000
--- a/problems/transform-to-chessboard/transform_to_chessboard_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem782
diff --git a/problems/transpose-file/README.md b/problems/transpose-file/README.md
deleted file mode 100644
index 4555a5929..000000000
--- a/problems/transpose-file/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-phone-numbers "Valid Phone Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../tenth-line "Tenth Line")
-
-## [194. Transpose File (Medium)](https://leetcode.com/problems/transpose-file "转置文件")
-
-<p>Given a text file <code>file.txt</code>, transpose its content.</p>
-
-<p>You may assume that each row has the same number of columns, and each field is separated by the <code>&#39; &#39;</code> character.</p>
-
-<p><strong>Example:</strong></p>
-
-<p>If <code>file.txt</code> has the following content:</p>
-
-<pre>
-name age
-alice 21
-ryan 30
-</pre>
-
-<p>Output the following:</p>
-
-<pre>
-name alice ryan
-age 21 30
-</pre>
-
-### Related Topics
-  [[Shell](../../tag/shell/README.md)]
diff --git a/problems/transpose-file/file.txt b/problems/transpose-file/file.txt
deleted file mode 100644
index c2d39ae0e..000000000
--- a/problems/transpose-file/file.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-name age
-alice 21
-ryan 30
diff --git a/problems/transpose-file/transpose_file.bash b/problems/transpose-file/transpose_file.bash
deleted file mode 100755
index 4698a11fe..000000000
--- a/problems/transpose-file/transpose_file.bash
+++ /dev/null
@@ -1,19 +0,0 @@
-#!/usr/bin/env bash
-
-# Read from the file file.txt and print its transposed content to stdout.
-
-awk '
-{
-    for (i = 1; i <= NF; i++) {
-        if(NR == 1) {
-            s[i] = $i;
-        } else {
-            s[i] = s[i] " " $i;
-        }
-    }
-}
-END {
-    for (i = 1; s[i] != ""; i++) {
-        print s[i];
-    }
-}' file.txt
diff --git a/problems/transpose-matrix/README.md b/problems/transpose-matrix/README.md
deleted file mode 100644
index df3a7aaa6..000000000
--- a/problems/transpose-matrix/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../prime-palindrome "Prime Palindrome")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-gap "Binary Gap")
-
-## [867. Transpose Matrix (Easy)](https://leetcode.com/problems/transpose-matrix "转置矩阵")
-
-<p>Given a 2D integer array <code>matrix</code>, return <em>the <strong>transpose</strong> of</em> <code>matrix</code>.</p>
-
-<p>The <strong>transpose</strong> of a matrix is the matrix flipped over its main diagonal, switching the matrix&#39;s row and column indices.</p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/02/10/hint_transpose.png" style="width: 600px; height: 197px;" /></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[1,2,3],[4,5,6],[7,8,9]]
-<strong>Output:</strong> [[1,4,7],[2,5,8],[3,6,9]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> matrix = [[1,2,3],[4,5,6]]
-<strong>Output:</strong> [[1,4],[2,5],[3,6]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == matrix.length</code></li>
-	<li><code>n == matrix[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 1000</code></li>
-	<li><code>1 &lt;= m * n &lt;= 10<sup>5</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= matrix[i][j] &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-We don't need any special algorithms to do this. You just need to know what the transpose of a matrix looks like. Rows become columns and vice versa!
-</details>
diff --git a/problems/transpose-matrix/transpose_matrix.go b/problems/transpose-matrix/transpose_matrix.go
deleted file mode 100644
index cb6d21c27..000000000
--- a/problems/transpose-matrix/transpose_matrix.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem867
-
-func transpose(A [][]int) [][]int {
-	m, n := len(A[0]), len(A)
-	B := make([][]int, m)
-	for i := 0; i < m; i++ {
-		B[i] = make([]int, n)
-	}
-	for i, row := range A {
-		for j, v := range row {
-			B[j][i] = v
-		}
-	}
-	return B
-}
diff --git a/problems/transpose-matrix/transpose_matrix_test.go b/problems/transpose-matrix/transpose_matrix_test.go
deleted file mode 100644
index cd12659e8..000000000
--- a/problems/transpose-matrix/transpose_matrix_test.go
+++ /dev/null
@@ -1,45 +0,0 @@
-package problem867
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	in   [][]int
-	want [][]int
-}
-
-func TestTranspose(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{1, 2, 3},
-				{4, 5, 6},
-				{7, 8, 9},
-			},
-			want: [][]int{
-				{1, 4, 7},
-				{2, 5, 8},
-				{3, 6, 9},
-			},
-		},
-		{
-			in: [][]int{
-				{1, 2, 3},
-				{4, 5, 6},
-			},
-			want: [][]int{
-				{1, 4},
-				{2, 5},
-				{3, 6},
-			},
-		},
-	}
-	for _, tt := range tests {
-		got := transpose(tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/trapping-rain-water-ii/README.md b/problems/trapping-rain-water-ii/README.md
deleted file mode 100644
index d7f037184..000000000
--- a/problems/trapping-rain-water-ii/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../queue-reconstruction-by-height "Queue Reconstruction by Height")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-word-abbreviation "Valid Word Abbreviation")
-
-## [407. Trapping Rain Water II (Hard)](https://leetcode.com/problems/trapping-rain-water-ii "接雨水 II")
-
-<p>Given an <code>m x n</code> integer matrix <code>heightMap</code> representing the height of each unit cell in a 2D elevation map, return <em>the volume of water it can trap after raining</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/trap1-3d.jpg" style="width: 361px; height: 321px;" />
-<pre>
-<strong>Input:</strong> heightMap = [[1,4,3,1,3,2],[3,2,1,3,2,4],[2,3,3,2,3,1]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> After the rain, water is trapped between the blocks.
-We have two small ponds 1 and 3 units trapped.
-The total volume of water trapped is 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/trap2-3d.jpg" style="width: 401px; height: 321px;" />
-<pre>
-<strong>Input:</strong> heightMap = [[3,3,3,3,3],[3,2,2,2,3],[3,2,1,2,3],[3,2,2,2,3],[3,3,3,3,3]]
-<strong>Output:</strong> 10
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == heightMap.length</code></li>
-	<li><code>n == heightMap[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 200</code></li>
-	<li><code>0 &lt;= heightMap[i][j] &lt;= 2 * 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Trapping Rain Water](../trapping-rain-water) (Hard)
diff --git a/problems/trapping-rain-water-ii/trapping_rain_water_ii.go b/problems/trapping-rain-water-ii/trapping_rain_water_ii.go
deleted file mode 100644
index e6fe2a7bc..000000000
--- a/problems/trapping-rain-water-ii/trapping_rain_water_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem407
diff --git a/problems/trapping-rain-water-ii/trapping_rain_water_ii_test.go b/problems/trapping-rain-water-ii/trapping_rain_water_ii_test.go
deleted file mode 100644
index e6fe2a7bc..000000000
--- a/problems/trapping-rain-water-ii/trapping_rain_water_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem407
diff --git a/problems/trapping-rain-water/README.md b/problems/trapping-rain-water/README.md
deleted file mode 100644
index 63809ff6f..000000000
--- a/problems/trapping-rain-water/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../first-missing-positive "First Missing Positive")
-　　　　　　　　　　　　　　　　
-[Next >](../multiply-strings "Multiply Strings")
-
-## [42. Trapping Rain Water (Hard)](https://leetcode.com/problems/trapping-rain-water "接雨水")
-
-<p>Given <code>n</code> non-negative integers representing an elevation map where the width of each bar is <code>1</code>, compute how much water it can trap after raining.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://assets.leetcode.com/uploads/2018/10/22/rainwatertrap.png" style="width: 412px; height: 161px;" />
-<pre>
-<strong>Input:</strong> height = [0,1,0,2,1,0,1,3,2,1,2,1]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The above elevation map (black section) is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of rain water (blue section) are being trapped.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> height = [4,2,0,3,2,5]
-<strong>Output:</strong> 9
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == height.length</code></li>
-	<li><code>1 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= height[i] &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-
-### Similar Questions
-  1. [Container With Most Water](../container-with-most-water) (Medium)
-  1. [Product of Array Except Self](../product-of-array-except-self) (Medium)
-  1. [Trapping Rain Water II](../trapping-rain-water-ii) (Hard)
-  1. [Pour Water](../pour-water) (Medium)
diff --git a/problems/trapping-rain-water/trapping_rain_water.go b/problems/trapping-rain-water/trapping_rain_water.go
deleted file mode 100644
index ccf446518..000000000
--- a/problems/trapping-rain-water/trapping_rain_water.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem42
diff --git a/problems/trapping-rain-water/trapping_rain_water_test.go b/problems/trapping-rain-water/trapping_rain_water_test.go
deleted file mode 100644
index ccf446518..000000000
--- a/problems/trapping-rain-water/trapping_rain_water_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem42
diff --git a/problems/tree-diameter/README.md b/problems/tree-diameter/README.md
deleted file mode 100644
index 2deb63430..000000000
--- a/problems/tree-diameter/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-a-leaderboard "Design A Leaderboard")
-　　　　　　　　　　　　　　　　
-[Next >](../palindrome-removal "Palindrome Removal")
-
-## [1245. Tree Diameter (Medium)](https://leetcode.com/problems/tree-diameter "树的直径")
-
-<p>Given an undirected tree, return&nbsp;its diameter: the number of <strong>edges</strong> in a longest path in that tree.</p>
-
-<p>The tree is given as an array&nbsp;of&nbsp;<code>edges</code>&nbsp;where <code>edges[i] = [u, v]</code> is a bidirectional edge between nodes&nbsp;<code>u</code> and <code>v</code>.&nbsp; Each node has&nbsp;labels in the set <code>{0, 1, ..., edges.length}</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/06/14/1397_example_1.PNG" style="width: 226px; height: 233px;" /></p>
-
-<pre>
-<strong>Input:</strong> edges = [[0,1],[0,2]]
-<strong>Output:</strong> 2
-<strong>Explanation: </strong>
-A longest path of the tree is the path 1 - 0 - 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/06/14/1397_example_2.PNG" style="width: 350px; height: 316px;" /></p>
-
-<pre>
-<strong>Input:</strong> edges = [[0,1],[1,2],[2,3],[1,4],[4,5]]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>
-A longest path of the tree is the path 3 - 2 - 1 - 4 - 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= edges.length &lt;&nbsp;10^4</code></li>
-	<li><code>edges[i][0] != edges[i][1]</code></li>
-	<li><code>0 &lt;= edges[i][j] &lt;= edges.length</code></li>
-	<li>The given edges form an undirected tree.</li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Count Subtrees With Max Distance Between Cities](../count-subtrees-with-max-distance-between-cities) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Start at any node A and traverse the tree to find the furthest node from it, let's call it B.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Having found the furthest node B, traverse the tree from B to find the furthest node from it, lets call it C.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The distance between B and C is the tree diameter.
-</details>
diff --git a/problems/tree-node/README.md b/problems/tree-node/README.md
deleted file mode 100644
index fb7de2645..000000000
--- a/problems/tree-node/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sales-person "Sales Person")
-　　　　　　　　　　　　　　　　
-[Next >](../find-duplicate-file-in-system "Find Duplicate File in System")
-
-## [608. Tree Node (Medium)](https://leetcode.com/problems/tree-node "树节点")
-
-<p>Given a table <code>tree</code>, <b>id</b> is identifier of the tree node and <b>p_id</b> is its parent node&#39;s <b>id</b>.</p>
-
-<pre>
-+----+------+
-| id | p_id |
-+----+------+
-| 1  | null |
-| 2  | 1    |
-| 3  | 1    |
-| 4  | 2    |
-| 5  | 2    |
-+----+------+
-</pre>
-Each node in the tree can be one of three types:
-
-<ul>
-	<li>Leaf: if the node is a leaf node.</li>
-	<li>Root: if the node is the root of the tree.</li>
-	<li>Inner: If the node is neither a leaf node nor a root node.</li>
-</ul>
-
-<p>&nbsp;</p>
-Write a query to print the node id and the type of the node. Sort your output by the node id. The result for the above sample is:
-
-<p>&nbsp;</p>
-
-<pre>
-+----+------+
-| id | Type |
-+----+------+
-| 1  | Root |
-| 2  | Inner|
-| 3  | Leaf |
-| 4  | Leaf |
-| 5  | Leaf |
-+----+------+
-</pre>
-
-<p>&nbsp;</p>
-
-<p><b>Explanation</b></p>
-
-<p>&nbsp;</p>
-
-<ul>
-	<li>Node &#39;1&#39; is root node, because its parent node is NULL and it has child node &#39;2&#39; and &#39;3&#39;.</li>
-	<li>Node &#39;2&#39; is inner node, because it has parent node &#39;1&#39; and child node &#39;4&#39; and &#39;5&#39;.</li>
-	<li>Node &#39;3&#39;, &#39;4&#39; and &#39;5&#39; is Leaf node, because they have parent node and they don&#39;t have child node.</li>
-	<br />
-	<li>And here is the image of the sample tree as below:
-	<p>&nbsp;</p>
-	<pre>
-			  1
-			/   \
-                      2       3
-                    /   \
-                  4       5
-</pre>
-	<p><b>Note</b></p>
-	<p>If there is only one node on the tree, you only need to output its root attributes.</p>
-	</li>
-</ul>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You can judge the node type by querying whether the node's id shows up in p_id column and whether the node's p_id is null.
-</details>
diff --git a/problems/tree-node/mysql_schemas.sql b/problems/tree-node/mysql_schemas.sql
deleted file mode 100644
index 85a4aefaa..000000000
--- a/problems/tree-node/mysql_schemas.sql
+++ /dev/null
@@ -1,7 +0,0 @@
-Create table If Not Exists Tree (id int, p_id int);
-Truncate table Tree;
-insert into Tree (id, p_id) values ('1', 'None');
-insert into Tree (id, p_id) values ('2', '1');
-insert into Tree (id, p_id) values ('3', '1');
-insert into Tree (id, p_id) values ('4', '2');
-insert into Tree (id, p_id) values ('5', '2');
diff --git a/problems/tree-node/tree_node.sql b/problems/tree-node/tree_node.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/tree-node/tree_node.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/tree-of-coprimes/README.md b/problems/tree-of-coprimes/README.md
deleted file mode 100644
index 14026bb81..000000000
--- a/problems/tree-of-coprimes/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../map-of-highest-peak "Map of Highest Peak")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-subtasks-that-did-not-execute "Find the Subtasks That Did Not Execute")
-
-## [1766. Tree of Coprimes (Hard)](https://leetcode.com/problems/tree-of-coprimes "互质树")
-
-<p>There is a tree (i.e.,&nbsp;a connected, undirected graph that has no cycles) consisting of <code>n</code> nodes numbered from <code>0</code> to <code>n - 1</code> and exactly <code>n - 1</code> edges. Each node has a value associated with it, and the <strong>root</strong> of the tree is node <code>0</code>.</p>
-
-<p>To represent this tree, you are given an integer array <code>nums</code> and a 2D array <code>edges</code>. Each <code>nums[i]</code> represents the <code>i<sup>th</sup></code> node&#39;s value, and each <code>edges[j] = [u<sub>j</sub>, v<sub>j</sub>]</code> represents an edge between nodes <code>u<sub>j</sub></code> and <code>v<sub>j</sub></code> in the tree.</p>
-
-<p>Two values <code>x</code> and <code>y</code> are <strong>coprime</strong> if <code>gcd(x, y) == 1</code> where <code>gcd(x, y)</code> is the <strong>greatest common divisor</strong> of <code>x</code> and <code>y</code>.</p>
-
-<p>An ancestor of a node <code>i</code> is any other node on the shortest path from node <code>i</code> to the <strong>root</strong>. A node is <strong>not </strong>considered an ancestor of itself.</p>
-
-<p>Return <em>an array </em><code>ans</code><em> of size </em><code>n</code>, <em>where </em><code>ans[i]</code><em> is the closest ancestor to node </em><code>i</code><em> such that </em><code>nums[i]</code> <em>and </em><code>nums[ans[i]]</code> are <strong>coprime</strong>, or <code>-1</code><em> if there is no such ancestor</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2021/01/06/untitled-diagram.png" style="width: 191px; height: 281px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,3,2], edges = [[0,1],[1,2],[1,3]]
-<strong>Output:</strong> [-1,0,0,1]
-<strong>Explanation:</strong> In the above figure, each node&#39;s value is in parentheses.
-- Node 0 has no coprime ancestors.
-- Node 1 has only one ancestor, node 0. Their values are coprime (gcd(2,3) == 1).
-- Node 2 has two ancestors, nodes 1 and 0. Node 1&#39;s value is not coprime (gcd(3,3) == 3), but node 0&#39;s
-  value is (gcd(2,3) == 1), so node 0 is the closest valid ancestor.
-- Node 3 has two ancestors, nodes 1 and 0. It is coprime with node 1 (gcd(3,2) == 1), so node 1 is its
-  closest valid ancestor.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2021/01/06/untitled-diagram1.png" style="width: 441px; height: 291px;" /></p>
-
-<pre>
-<strong>Input:</strong> nums = [5,6,10,2,3,6,15], edges = [[0,1],[0,2],[1,3],[1,4],[2,5],[2,6]]
-<strong>Output:</strong> [-1,0,-1,0,0,0,-1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>nums.length == n</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 50</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>edges.length == n - 1</code></li>
-	<li><code>edges[j].length == 2</code></li>
-	<li><code>0 &lt;= u<sub>j</sub>, v<sub>j</sub> &lt; n</code></li>
-	<li><code>u<sub>j</sub> != v<sub>j</sub></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that for a node, it's not optimal to consider two nodes with the same value.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Note that the values are small enough for you to iterate over them instead of iterating over the parent nodes.
-</details>
diff --git a/problems/triangle-judgement/README.md b/problems/triangle-judgement/README.md
deleted file mode 100644
index c2e4a3e2d..000000000
--- a/problems/triangle-judgement/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-duplicate-file-in-system "Find Duplicate File in System")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-triangle-number "Valid Triangle Number")
-
-## [610. Triangle Judgement (Easy)](https://leetcode.com/problems/triangle-judgement "判断三角形")
-
-A pupil Tim gets homework to identify whether three line segments could possibly form a triangle.
-<p>&nbsp;</p>
-However, this assignment is very heavy because there are hundreds of records to calculate.
-
-<p>&nbsp;</p>
-Could you help Tim by writing a query to judge whether these three sides can form a triangle, assuming table <code>triangle</code> holds the length of the three sides x, y and z.
-
-<p>&nbsp;</p>
-
-<pre>
-| x  | y  | z  |
-|----|----|----|
-| 13 | 15 | 30 |
-| 10 | 20 | 15 |
-</pre>
-For the sample data above, your query should return the follow result:
-
-<pre>
-| x  | y  | z  | triangle |
-|----|----|----|----------|
-| 13 | 15 | 30 | No       |
-| 10 | 20 | 15 | Yes      |
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/triangle-judgement/mysql_schemas.sql b/problems/triangle-judgement/mysql_schemas.sql
deleted file mode 100644
index 3f64d0d37..000000000
--- a/problems/triangle-judgement/mysql_schemas.sql
+++ /dev/null
@@ -1,4 +0,0 @@
-Create table If Not Exists Triangle (x int, y int, z int);
-Truncate table Triangle;
-insert into Triangle (x, y, z) values ('13', '15', '30');
-insert into Triangle (x, y, z) values ('10', '20', '15');
diff --git a/problems/triangle-judgement/triangle_judgement.sql b/problems/triangle-judgement/triangle_judgement.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/triangle-judgement/triangle_judgement.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/triangle/README.md b/problems/triangle/README.md
deleted file mode 100644
index 645657618..000000000
--- a/problems/triangle/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../pascals-triangle-ii "Pascal's Triangle II")
-　　　　　　　　　　　　　　　　
-[Next >](../best-time-to-buy-and-sell-stock "Best Time to Buy and Sell Stock")
-
-## [120. Triangle (Medium)](https://leetcode.com/problems/triangle "三角形最小路径和")
-
-<p>Given a <code>triangle</code> array, return <em>the minimum path sum from top to bottom</em>.</p>
-
-<p>For each step, you may move to an adjacent number of the row below. More formally, if you are on index <code>i</code> on the current row, you may move to either index <code>i</code> or index <code>i + 1</code> on the next row.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> triangle = [[2],[3,4],[6,5,7],[4,1,8,3]]
-<strong>Output:</strong> 11
-<strong>Explanation:</strong> The triangle looks like:
-   <u>2</u>
-  <u>3</u> 4
- 6 <u>5</u> 7
-4 <u>1</u> 8 3
-The minimum path sum from top to bottom is 2 + 3 + 5 + 1 = 11 (underlined above).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> triangle = [[-10]]
-<strong>Output:</strong> -10
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= triangle.length &lt;= 200</code></li>
-	<li><code>triangle[0].length == 1</code></li>
-	<li><code>triangle[i].length == triangle[i - 1].length + 1</code></li>
-	<li><code>-10<sup>4</sup> &lt;= triangle[i][j] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow up:</strong> Could you&nbsp;do this using only <code>O(n)</code> extra space, where <code>n</code> is the total number of rows in the triangle?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/triangle/triangle.go b/problems/triangle/triangle.go
deleted file mode 100644
index b5bc0c64f..000000000
--- a/problems/triangle/triangle.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem120
diff --git a/problems/triangle/triangle_test.go b/problems/triangle/triangle_test.go
deleted file mode 100644
index b5bc0c64f..000000000
--- a/problems/triangle/triangle_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem120
diff --git a/problems/trim-a-binary-search-tree/README.md b/problems/trim-a-binary-search-tree/README.md
deleted file mode 100644
index 1062536dd..000000000
--- a/problems/trim-a-binary-search-tree/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-smallest-number-in-multiplication-table "Kth Smallest Number in Multiplication Table")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-swap "Maximum Swap")
-
-## [669. Trim a Binary Search Tree (Medium)](https://leetcode.com/problems/trim-a-binary-search-tree "修剪二叉搜索树")
-
-<p>Given the <code>root</code> of a binary search tree and the lowest and highest boundaries as <code>low</code> and <code>high</code>, trim the tree so that all its elements lies in <code>[low, high]</code>. Trimming the tree should <strong>not</strong> change the relative structure of the elements that will remain in the tree (i.e., any node&#39;s descendant should remain a descendant). It can be proven that there is a <strong>unique answer</strong>.</p>
-
-<p>Return <em>the root of the trimmed binary search tree</em>. Note that the root may change depending on the given bounds.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/09/trim1.jpg" style="width: 450px; height: 126px;" />
-<pre>
-<strong>Input:</strong> root = [1,0,2], low = 1, high = 2
-<strong>Output:</strong> [1,null,2]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/09/trim2.jpg" style="width: 450px; height: 277px;" />
-<pre>
-<strong>Input:</strong> root = [3,0,4,null,2,null,null,1], low = 1, high = 3
-<strong>Output:</strong> [3,2,null,1]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1], low = 1, high = 2
-<strong>Output:</strong> [1]
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,2], low = 1, high = 3
-<strong>Output:</strong> [1,null,2]
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [1,null,2], low = 2, high = 4
-<strong>Output:</strong> [2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-	<li>The value of each node in the tree is <strong>unique</strong>.</li>
-	<li><code>root</code> is guaranteed to be a valid binary search tree.</li>
-	<li><code>0 &lt;= low &lt;= high &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/trim-a-binary-search-tree/trim_a_binary_search_tree.go b/problems/trim-a-binary-search-tree/trim_a_binary_search_tree.go
deleted file mode 100644
index 6410e4be5..000000000
--- a/problems/trim-a-binary-search-tree/trim_a_binary_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem669
diff --git a/problems/trim-a-binary-search-tree/trim_a_binary_search_tree_test.go b/problems/trim-a-binary-search-tree/trim_a_binary_search_tree_test.go
deleted file mode 100644
index 6410e4be5..000000000
--- a/problems/trim-a-binary-search-tree/trim_a_binary_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem669
diff --git a/problems/triples-with-bitwise-and-equal-to-zero/README.md b/problems/triples-with-bitwise-and-equal-to-zero/README.md
deleted file mode 100644
index 289e966c4..000000000
--- a/problems/triples-with-bitwise-and-equal-to-zero/README.md
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../time-based-key-value-store "Time Based Key-Value Store")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-for-tickets "Minimum Cost For Tickets")
-
-## [982. Triples with Bitwise AND Equal To Zero (Hard)](https://leetcode.com/problems/triples-with-bitwise-and-equal-to-zero "按位与为零的三元组")
-
-<p>Given an integer array nums, return <em>the number of <strong>AND triples</strong></em>.</p>
-
-<p>An <strong>AND triple</strong> is a triple of indices <code>(i, j, k)</code> such that:</p>
-
-<ul>
-	<li><code>0 &lt;= i &lt; nums.length</code></li>
-	<li><code>0 &lt;= j &lt; nums.length</code></li>
-	<li><code>0 &lt;= k &lt; nums.length</code></li>
-	<li><code>nums[i] &amp; nums[j] &amp; nums[k] == 0</code>, where <code>&amp;</code> represents the bitwise-AND operator.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,3]
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> We could choose the following i, j, k triples:
-(i=0, j=0, k=1) : 2 &amp; 2 &amp; 1
-(i=0, j=1, k=0) : 2 &amp; 1 &amp; 2
-(i=0, j=1, k=1) : 2 &amp; 1 &amp; 1
-(i=0, j=1, k=2) : 2 &amp; 1 &amp; 3
-(i=0, j=2, k=1) : 2 &amp; 3 &amp; 1
-(i=1, j=0, k=0) : 1 &amp; 2 &amp; 2
-(i=1, j=0, k=1) : 1 &amp; 2 &amp; 1
-(i=1, j=0, k=2) : 1 &amp; 2 &amp; 3
-(i=1, j=1, k=0) : 1 &amp; 1 &amp; 2
-(i=1, j=2, k=0) : 1 &amp; 3 &amp; 2
-(i=2, j=0, k=1) : 3 &amp; 2 &amp; 1
-(i=2, j=1, k=0) : 3 &amp; 1 &amp; 2
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [0,0,0]
-<strong>Output:</strong> 27
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt; 2<sup>16</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
diff --git a/problems/triples-with-bitwise-and-equal-to-zero/triples_with_bitwise_and_equal_to_zero.go b/problems/triples-with-bitwise-and-equal-to-zero/triples_with_bitwise_and_equal_to_zero.go
deleted file mode 100644
index 1594a1b81..000000000
--- a/problems/triples-with-bitwise-and-equal-to-zero/triples_with_bitwise_and_equal_to_zero.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem982
diff --git a/problems/trips-and-users/README.md b/problems/trips-and-users/README.md
deleted file mode 100644
index 37733ca07..000000000
--- a/problems/trips-and-users/README.md
+++ /dev/null
@@ -1,124 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../graph-valid-tree "Graph Valid Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../ugly-number "Ugly Number")
-
-## [262. Trips and Users (Hard)](https://leetcode.com/problems/trips-and-users "行程和用户")
-
-<p>Table: <code>Trips</code></p>
-
-<pre>
-+-------------+----------+
-| Column Name | Type     |
-+-------------+----------+
-| id          | int      |
-| client_id   | int      |
-| driver_id   | int      |
-| city_id     | int      |
-| status      | enum     |
-| request_at  | date     |     
-+-------------+----------+
-id is the primary key for this table.
-The table holds all taxi trips. Each trip has a unique id, while client_id and driver_id are foreign keys to the users_id at the Users table.
-Status is an ENUM type of (&#39;completed&#39;, &#39;cancelled_by_driver&#39;, &#39;cancelled_by_client&#39;).
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Table: <code>Users</code></p>
-
-<pre>
-+-------------+----------+
-| Column Name | Type     |
-+-------------+----------+
-| users_id    | int      |
-| banned      | enum     |
-| role        | enum     |
-+-------------+----------+
-users_id is the primary key for this table.
-The table holds all users. Each user has a unique users_id, and role is an ENUM type of (&#39;client&#39;, &#39;driver&#39;, &#39;partner&#39;).
-banned is an ENUM type of (&#39;Yes&#39;, &#39;No&#39;).
-</pre>
-
-<p>&nbsp;</p>
-
-<p>The <strong>cancellation rate</strong> is computed by dividing the number of canceled (by client or driver) requests with unbanned users by the total number of requests with unbanned users on that day.</p>
-
-<p>Write a SQL query to find the <strong>cancellation rate</strong> of requests with unbanned users (<strong>both client and driver must not be banned</strong>) each day between <code>&quot;2013-10-01&quot;</code> and <code>&quot;2013-10-03&quot;</code>. Round <code>Cancellation Rate</code> to <strong>two decimal</strong> points.</p>
-
-<p>Return the result table in <strong>any order</strong>.</p>
-
-<p>The query result format is in the following example.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> 
-Trips table:
-+----+-----------+-----------+---------+---------------------+------------+
-| id | client_id | driver_id | city_id | status              | request_at |
-+----+-----------+-----------+---------+---------------------+------------+
-| 1  | 1         | 10        | 1       | completed           | 2013-10-01 |
-| 2  | 2         | 11        | 1       | cancelled_by_driver | 2013-10-01 |
-| 3  | 3         | 12        | 6       | completed           | 2013-10-01 |
-| 4  | 4         | 13        | 6       | cancelled_by_client | 2013-10-01 |
-| 5  | 1         | 10        | 1       | completed           | 2013-10-02 |
-| 6  | 2         | 11        | 6       | completed           | 2013-10-02 |
-| 7  | 3         | 12        | 6       | completed           | 2013-10-02 |
-| 8  | 2         | 12        | 12      | completed           | 2013-10-03 |
-| 9  | 3         | 10        | 12      | completed           | 2013-10-03 |
-| 10 | 4         | 13        | 12      | cancelled_by_driver | 2013-10-03 |
-+----+-----------+-----------+---------+---------------------+------------+
-Users table:
-+----------+--------+--------+
-| users_id | banned | role   |
-+----------+--------+--------+
-| 1        | No     | client |
-| 2        | Yes    | client |
-| 3        | No     | client |
-| 4        | No     | client |
-| 10       | No     | driver |
-| 11       | No     | driver |
-| 12       | No     | driver |
-| 13       | No     | driver |
-+----------+--------+--------+
-<strong>Output:</strong> 
-+------------+-------------------+
-| Day        | Cancellation Rate |
-+------------+-------------------+
-| 2013-10-01 | 0.33              |
-| 2013-10-02 | 0.00              |
-| 2013-10-03 | 0.50              |
-+------------+-------------------+
-<strong>Explanation:</strong> 
-On 2013-10-01:
-  - There were 4 requests in total, 2 of which were canceled.
-  - However, the request with Id=2 was made by a banned client (User_Id=2), so it is ignored in the calculation.
-  - Hence there are 3 unbanned requests in total, 1 of which was canceled.
-  - The Cancellation Rate is (1 / 3) = 0.33
-On 2013-10-02:
-  - There were 3 requests in total, 0 of which were canceled.
-  - The request with Id=6 was made by a banned client, so it is ignored.
-  - Hence there are 2 unbanned requests in total, 0 of which were canceled.
-  - The Cancellation Rate is (0 / 2) = 0.00
-On 2013-10-03:
-  - There were 3 requests in total, 1 of which was canceled.
-  - The request with Id=8 was made by a banned client, so it is ignored.
-  - Hence there are 2 unbanned request in total, 1 of which were canceled.
-  - The Cancellation Rate is (1 / 2) = 0.50
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
-
-### Similar Questions
-  1. [Hopper Company Queries I](../hopper-company-queries-i) (Hard)
-  1. [Hopper Company Queries II](../hopper-company-queries-ii) (Hard)
-  1. [Hopper Company Queries III](../hopper-company-queries-iii) (Hard)
diff --git a/problems/trips-and-users/mysql_schemas.sql b/problems/trips-and-users/mysql_schemas.sql
deleted file mode 100644
index eb8b97370..000000000
--- a/problems/trips-and-users/mysql_schemas.sql
+++ /dev/null
@@ -1,22 +0,0 @@
-Create table If Not Exists Trips (id int, client_id int, driver_id int, city_id int, status ENUM('completed', 'cancelled_by_driver', 'cancelled_by_client'), request_at varchar(50));
-Create table If Not Exists Users (users_id int, banned varchar(50), role ENUM('client', 'driver', 'partner'));
-Truncate table Trips;
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('1', '1', '10', '1', 'completed', '2013-10-01');
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('2', '2', '11', '1', 'cancelled_by_driver', '2013-10-01');
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('3', '3', '12', '6', 'completed', '2013-10-01');
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('4', '4', '13', '6', 'cancelled_by_client', '2013-10-01');
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('5', '1', '10', '1', 'completed', '2013-10-02');
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('6', '2', '11', '6', 'completed', '2013-10-02');
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('7', '3', '12', '6', 'completed', '2013-10-02');
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('8', '2', '12', '12', 'completed', '2013-10-03');
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('9', '3', '10', '12', 'completed', '2013-10-03');
-insert into Trips (id, client_id, driver_id, city_id, status, request_at) values ('10', '4', '13', '12', 'cancelled_by_driver', '2013-10-03');
-Truncate table Users;
-insert into Users (users_id, banned, role) values ('1', 'No', 'client');
-insert into Users (users_id, banned, role) values ('2', 'Yes', 'client');
-insert into Users (users_id, banned, role) values ('3', 'No', 'client');
-insert into Users (users_id, banned, role) values ('4', 'No', 'client');
-insert into Users (users_id, banned, role) values ('10', 'No', 'driver');
-insert into Users (users_id, banned, role) values ('11', 'No', 'driver');
-insert into Users (users_id, banned, role) values ('12', 'No', 'driver');
-insert into Users (users_id, banned, role) values ('13', 'No', 'driver');
diff --git a/problems/trips-and-users/trips_and_users.sql b/problems/trips-and-users/trips_and_users.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/trips-and-users/trips_and_users.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/truncate-sentence/README.md b/problems/truncate-sentence/README.md
deleted file mode 100644
index 80201d24e..000000000
--- a/problems/truncate-sentence/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-groups-getting-fresh-donuts "Maximum Number of Groups Getting Fresh Donuts")
-　　　　　　　　　　　　　　　　
-[Next >](../finding-the-users-active-minutes "Finding the Users Active Minutes")
-
-## [1816. Truncate Sentence (Easy)](https://leetcode.com/problems/truncate-sentence "截断句子")
-
-<p>A <strong>sentence</strong> is a list of words that are separated by a single space with no leading or trailing spaces. Each of the words consists of <strong>only</strong> uppercase and lowercase English letters (no punctuation).</p>
-
-<ul>
-	<li>For example, <code>&quot;Hello World&quot;</code>, <code>&quot;HELLO&quot;</code>, and <code>&quot;hello world hello world&quot;</code> are all sentences.</li>
-</ul>
-
-<p>You are given a sentence <code>s</code>​​​​​​ and an integer <code>k</code>​​​​​​. You want to <strong>truncate</strong> <code>s</code>​​​​​​ such that it contains only the <strong>first</strong> <code>k</code>​​​​​​ words. Return <code>s</code>​​​​<em>​​ after <strong>truncating</strong> it.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;Hello how are you Contestant&quot;, k = 4
-<strong>Output:</strong> &quot;Hello how are you&quot;
-<strong>Explanation:</strong>
-The words in s are [&quot;Hello&quot;, &quot;how&quot; &quot;are&quot;, &quot;you&quot;, &quot;Contestant&quot;].
-The first 4 words are [&quot;Hello&quot;, &quot;how&quot;, &quot;are&quot;, &quot;you&quot;].
-Hence, you should return &quot;Hello how are you&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;What is the solution to this problem&quot;, k = 4
-<strong>Output:</strong> &quot;What is the solution&quot;
-<strong>Explanation:</strong>
-The words in s are [&quot;What&quot;, &quot;is&quot; &quot;the&quot;, &quot;solution&quot;, &quot;to&quot;, &quot;this&quot;, &quot;problem&quot;].
-The first 4 words are [&quot;What&quot;, &quot;is&quot;, &quot;the&quot;, &quot;solution&quot;].
-Hence, you should return &quot;What is the solution&quot;.</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;chopper is not a tanuki&quot;, k = 5
-<strong>Output:</strong> &quot;chopper is not a tanuki&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 500</code></li>
-	<li><code>k</code> is in the range <code>[1, the number of words in s]</code>.</li>
-	<li><code>s</code> consist of only lowercase and uppercase English letters and spaces.</li>
-	<li>The words in <code>s</code> are separated by a single space.</li>
-	<li>There are no leading or trailing spaces.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-It's easier to solve this problem on an array of strings so parse the string to an array of words
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After return the first k words as a sentence
-</details>
diff --git a/problems/tuple-with-same-product/README.md b/problems/tuple-with-same-product/README.md
deleted file mode 100644
index bca35af2d..000000000
--- a/problems/tuple-with-same-product/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-rectangles-that-can-form-the-largest-square "Number Of Rectangles That Can Form The Largest Square")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-submatrix-with-rearrangements "Largest Submatrix With Rearrangements")
-
-## [1726. Tuple with Same Product (Medium)](https://leetcode.com/problems/tuple-with-same-product "同积元组")
-
-<p>Given an array <code>nums</code> of <strong>distinct</strong> positive integers, return <em>the number of tuples </em><code>(a, b, c, d)</code><em> such that </em><code>a * b = c * d</code><em> where </em><code>a</code><em>, </em><code>b</code><em>, </em><code>c</code><em>, and </em><code>d</code><em> are elements of </em><code>nums</code><em>, and </em><code>a != b != c != d</code><em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,3,4,6]
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> There are 8 valid tuples:
-(2,6,3,4) , (2,6,4,3) , (6,2,3,4) , (6,2,4,3)
-(3,4,2,6) , (4,3,2,6) , (3,4,6,2) , (4,3,6,2)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,4,5,10]
-<strong>Output:</strong> 16
-<strong>Explanation:</strong> There are 16 valid tuples:
-(1,10,2,5) , (1,10,5,2) , (10,1,2,5) , (10,1,5,2)
-(2,5,1,10) , (2,5,10,1) , (5,2,1,10) , (5,2,10,1)
-(2,10,4,5) , (2,10,5,4) , (10,2,4,5) , (10,2,5,4)
-(4,5,2,10) , (4,5,10,2) , (5,4,2,10) , (5,4,10,2)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-	<li>All elements in <code>nums</code> are <strong>distinct</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Note that all of the integers are distinct. This means that each time a product is formed it must be formed by two unique integers.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Count the frequency of each product of 2 distinct numbers. Then calculate the permutations formed.
-</details>
diff --git a/problems/tweet-counts-per-frequency/README.md b/problems/tweet-counts-per-frequency/README.md
deleted file mode 100644
index ec49dcb06..000000000
--- a/problems/tweet-counts-per-frequency/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-number-of-steps-to-make-two-strings-anagram "Minimum Number of Steps to Make Two Strings Anagram")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-students-taking-exam "Maximum Students Taking Exam")
-
-## [1348. Tweet Counts Per Frequency (Medium)](https://leetcode.com/problems/tweet-counts-per-frequency "推文计数")
-
-<p>A social media company is trying to monitor activity on their site by analyzing the number of tweets that occur in select periods of time. These periods can be partitioned into smaller <strong>time chunks</strong> based on a certain frequency (every <strong>minute</strong>, <strong>hour</strong>, or <strong>day</strong>).</p>
-
-<p>For example, the period <code>[10, 10000]</code> (in <strong>seconds</strong>) would be partitioned into the following <strong>time chunks</strong> with these frequencies:</p>
-
-<ul>
-	<li>Every <strong>minute</strong> (60-second chunks): <code>[10,69]</code>, <code>[70,129]</code>, <code>[130,189]</code>, <code>...</code>, <code>[9970,10000]</code></li>
-	<li>Every <strong>hour</strong> (3600-second chunks): <code>[10,3609]</code>, <code>[3610,7209]</code>, <code>[7210,10000]</code></li>
-	<li>Every <strong>day</strong> (86400-second chunks): <code>[10,10000]</code></li>
-</ul>
-
-<p>Notice that the last chunk may be shorter than the specified frequency&#39;s chunk size and will always end with the end time of the period (<code>10000</code> in the above example).</p>
-
-<p>Design and implement an API to help the company with their analysis.</p>
-
-<p>Implement the <code>TweetCounts</code> class:</p>
-
-<ul>
-	<li><code>TweetCounts()</code> Initializes the <code>TweetCounts</code> object.</li>
-	<li><code>void recordTweet(String tweetName, int time)</code> Stores the <code>tweetName</code> at the recorded <code>time</code> (in <strong>seconds</strong>).</li>
-	<li><code>List&lt;Integer&gt; getTweetCountsPerFrequency(String freq, String tweetName, int startTime, int endTime)</code> Returns a list of integers representing the number of tweets with <code>tweetName</code> in each <strong>time chunk</strong> for the given period of time <code>[startTime, endTime]</code> (in <strong>seconds</strong>) and frequency <code>freq</code>.
-	<ul>
-		<li><code>freq</code> is one of <code>&quot;minute&quot;</code>, <code>&quot;hour&quot;</code>, or <code>&quot;day&quot;</code> representing a frequency of every <strong>minute</strong>, <strong>hour</strong>, or <strong>day</strong> respectively.</li>
-	</ul>
-	</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input</strong>
-[&quot;TweetCounts&quot;,&quot;recordTweet&quot;,&quot;recordTweet&quot;,&quot;recordTweet&quot;,&quot;getTweetCountsPerFrequency&quot;,&quot;getTweetCountsPerFrequency&quot;,&quot;recordTweet&quot;,&quot;getTweetCountsPerFrequency&quot;]
-[[],[&quot;tweet3&quot;,0],[&quot;tweet3&quot;,60],[&quot;tweet3&quot;,10],[&quot;minute&quot;,&quot;tweet3&quot;,0,59],[&quot;minute&quot;,&quot;tweet3&quot;,0,60],[&quot;tweet3&quot;,120],[&quot;hour&quot;,&quot;tweet3&quot;,0,210]]
-
-<strong>Output</strong>
-[null,null,null,null,[2],[2,1],null,[4]]
-
-<strong>Explanation</strong>
-TweetCounts tweetCounts = new TweetCounts();
-tweetCounts.recordTweet(&quot;tweet3&quot;, 0);                              // New tweet &quot;tweet3&quot; at time 0
-tweetCounts.recordTweet(&quot;tweet3&quot;, 60);                             // New tweet &quot;tweet3&quot; at time 60
-tweetCounts.recordTweet(&quot;tweet3&quot;, 10);                             // New tweet &quot;tweet3&quot; at time 10
-tweetCounts.getTweetCountsPerFrequency(&quot;minute&quot;, &quot;tweet3&quot;, 0, 59); // return [2]; chunk [0,59] had 2 tweets
-tweetCounts.getTweetCountsPerFrequency(&quot;minute&quot;, &quot;tweet3&quot;, 0, 60); // return [2,1]; chunk [0,59] had 2 tweets, chunk [60,60] had 1 tweet
-tweetCounts.recordTweet(&quot;tweet3&quot;, 120);                            // New tweet &quot;tweet3&quot; at time 120
-tweetCounts.getTweetCountsPerFrequency(&quot;hour&quot;, &quot;tweet3&quot;, 0, 210);  // return [4]; chunk [0,210] had 4 tweets
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= time, startTime, endTime &lt;= 10<sup>9</sup></code></li>
-	<li><code>0 &lt;= endTime - startTime &lt;= 10<sup>4</sup></code></li>
-	<li>There will be at most <code>10<sup>4</sup></code> calls <strong>in total</strong> to <code>recordTweet</code> and <code>getTweetCountsPerFrequency</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Ordered Set](../../tag/ordered-set/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/two-best-non-overlapping-events/README.md b/problems/two-best-non-overlapping-events/README.md
deleted file mode 100644
index 4526374a2..000000000
--- a/problems/two-best-non-overlapping-events/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../kth-distinct-string-in-an-array "Kth Distinct String in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../plates-between-candles "Plates Between Candles")
-
-## [2054. Two Best Non-Overlapping Events (Medium)](https://leetcode.com/problems/two-best-non-overlapping-events "两个最好的不重叠活动")
-
-<p>You are given a <strong>0-indexed</strong> 2D integer array of <code>events</code> where <code>events[i] = [startTime<sub>i</sub>, endTime<sub>i</sub>, value<sub>i</sub>]</code>. The <code>i<sup>th</sup></code> event starts at <code>startTime<sub>i</sub></code><sub> </sub>and ends at <code>endTime<sub>i</sub></code>, and if you attend this event, you will receive a value of <code>value<sub>i</sub></code>. You can choose <strong>at most</strong> <strong>two</strong> <strong>non-overlapping</strong> events to attend such that the sum of their values is <strong>maximized</strong>.</p>
-
-<p>Return <em>this <strong>maximum</strong> sum.</em></p>
-
-<p>Note that the start time and end time is <strong>inclusive</strong>: that is, you cannot attend two events where one of them starts and the other ends at the same time. More specifically, if you attend an event with end time <code>t</code>, the next event must start at or after <code>t + 1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/21/picture5.png" style="width: 400px; height: 75px;" />
-<pre>
-<strong>Input:</strong> events = [[1,3,2],[4,5,2],[2,4,3]]
-<strong>Output:</strong> 4
-<strong>Explanation: </strong>Choose the green events, 0 and 1 for a sum of 2 + 2 = 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="Example 1 Diagram" src="https://assets.leetcode.com/uploads/2021/09/21/picture1.png" style="width: 400px; height: 77px;" />
-<pre>
-<strong>Input:</strong> events = [[1,3,2],[4,5,2],[1,5,5]]
-<strong>Output:</strong> 5
-<strong>Explanation: </strong>Choose event 2 for a sum of 5.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/09/21/picture3.png" style="width: 400px; height: 66px;" />
-<pre>
-<strong>Input:</strong> events = [[1,5,3],[1,5,1],[6,6,5]]
-<strong>Output:</strong> 8
-<strong>Explanation: </strong>Choose events 0 and 2 for a sum of 3 + 5 = 8.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= events.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>events[i].length == 3</code></li>
-	<li><code>1 &lt;= startTime<sub>i</sub> &lt;= endTime<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= value<sub>i</sub> &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can sorting the events on the basis of their start times help? How about end times?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we quickly get the maximum score of an interval not intersecting with the interval we chose?
-</details>
diff --git a/problems/two-city-scheduling/README.md b/problems/two-city-scheduling/README.md
deleted file mode 100644
index 854fd250e..000000000
--- a/problems/two-city-scheduling/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../recover-a-tree-from-preorder-traversal "Recover a Tree From Preorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../matrix-cells-in-distance-order "Matrix Cells in Distance Order")
-
-## [1029. Two City Scheduling (Medium)](https://leetcode.com/problems/two-city-scheduling "两地调度")
-
-<p>A company is planning to interview <code>2n</code> people. Given the array <code>costs</code> where <code>costs[i] = [aCost<sub>i</sub>, bCost<sub>i</sub>]</code>,&nbsp;the cost of flying the <code>i<sup>th</sup></code> person to city <code>a</code> is <code>aCost<sub>i</sub></code>, and the cost of flying the <code>i<sup>th</sup></code> person to city <code>b</code> is <code>bCost<sub>i</sub></code>.</p>
-
-<p>Return <em>the minimum cost to fly every person to a city</em> such that exactly <code>n</code> people arrive in each city.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> costs = [[10,20],[30,200],[400,50],[30,20]]
-<strong>Output:</strong> 110
-<strong>Explanation: </strong>
-The first person goes to city A for a cost of 10.
-The second person goes to city A for a cost of 30.
-The third person goes to city B for a cost of 50.
-The fourth person goes to city B for a cost of 20.
-
-The total minimum cost is 10 + 30 + 50 + 20 = 110 to have half the people interviewing in each city.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> costs = [[259,770],[448,54],[926,667],[184,139],[840,118],[577,469]]
-<strong>Output:</strong> 1859
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> costs = [[515,563],[451,713],[537,709],[343,819],[855,779],[457,60],[650,359],[631,42]]
-<strong>Output:</strong> 3086
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 * n == costs.length</code></li>
-	<li><code>2 &lt;= costs.length &lt;= 100</code></li>
-	<li><code>costs.length</code> is even.</li>
-	<li><code>1 &lt;= aCost<sub>i</sub>, bCost<sub>i</sub> &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
diff --git a/problems/two-city-scheduling/two_city_scheduling.go b/problems/two-city-scheduling/two_city_scheduling.go
deleted file mode 100644
index f3848be0f..000000000
--- a/problems/two-city-scheduling/two_city_scheduling.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem1029
-
-import "sort"
-
-func twoCitySchedCost(costs [][]int) int {
-	sort.Slice(costs, func(i, j int) bool {
-		return abs(costs[i][0]-costs[i][1]) > abs(costs[j][0]-costs[j][1])
-	})
-	cost, a, b, n := 0, 0, 0, len(costs)/2
-	for _, c := range costs {
-		if (c[0] < c[1] && a < n) || b == n {
-			cost += c[0]
-			a++
-		} else {
-			cost += c[1]
-			b++
-		}
-	}
-	return cost
-}
-
-func abs(x int) int {
-	if x < 0 {
-		return -x
-	}
-	return x
-}
diff --git a/problems/two-city-scheduling/two_city_scheduling_test.go b/problems/two-city-scheduling/two_city_scheduling_test.go
deleted file mode 100644
index 00ec9619a..000000000
--- a/problems/two-city-scheduling/two_city_scheduling_test.go
+++ /dev/null
@@ -1,58 +0,0 @@
-package problem1029
-
-import "testing"
-
-type testType struct {
-	in   [][]int
-	want int
-}
-
-func TestTwoCitySchedCost(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{10, 20},
-				{30, 200},
-				{400, 50},
-				{30, 20},
-			},
-			want: 110,
-		},
-		{
-			in: [][]int{
-				{259, 770},
-				{448, 54},
-				{926, 667},
-				{184, 139},
-				{840, 118},
-				{577, 469},
-			},
-			want: 1859,
-		},
-		{
-			in: [][]int{
-				{918, 704},
-				{77, 778},
-				{239, 457},
-				{284, 263},
-				{872, 779},
-				{976, 416},
-				{860, 518},
-				{13, 351},
-				{137, 238},
-				{557, 596},
-				{890, 227},
-				{548, 143},
-				{384, 585},
-				{165, 54},
-			},
-			want: 4532,
-		},
-	}
-	for _, tt := range tests {
-		got := twoCitySchedCost(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/two-furthest-houses-with-different-colors/README.md b/problems/two-furthest-houses-with-different-colors/README.md
deleted file mode 100644
index 0cb4b8ae4..000000000
--- a/problems/two-furthest-houses-with-different-colors/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../paths-in-maze-that-lead-to-same-room "Paths in Maze That Lead to Same Room")
-　　　　　　　　　　　　　　　　
-[Next >](../watering-plants "Watering Plants")
-
-## [2078. Two Furthest Houses With Different Colors (Easy)](https://leetcode.com/problems/two-furthest-houses-with-different-colors "两栋颜色不同且距离最远的房子")
-
-<p>There are <code>n</code> houses evenly lined up on the street, and each house is beautifully painted. You are given a <strong>0-indexed</strong> integer array <code>colors</code> of length <code>n</code>, where <code>colors[i]</code> represents the color of the <code>i<sup>th</sup></code> house.</p>
-
-<p>Return <em>the <strong>maximum</strong> distance between <strong>two</strong> houses with <strong>different</strong> colors</em>.</p>
-
-<p>The distance between the <code>i<sup>th</sup></code> and <code>j<sup>th</sup></code> houses is <code>abs(i - j)</code>, where <code>abs(x)</code> is the <strong>absolute value</strong> of <code>x</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/31/eg1.png" style="width: 610px; height: 84px;" />
-<pre>
-<strong>Input:</strong> colors = [<u><strong>1</strong></u>,1,1,<strong><u>6</u></strong>,1,1,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> In the above image, color 1 is blue, and color 6 is red.
-The furthest two houses with different colors are house 0 and house 3.
-House 0 has color 1, and house 3 has color 6. The distance between them is abs(0 - 3) = 3.
-Note that houses 3 and 6 can also produce the optimal answer.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/10/31/eg2.png" style="width: 426px; height: 84px;" />
-<pre>
-<strong>Input:</strong> colors = [<u><strong>1</strong></u>,8,3,8,<u><strong>3</strong></u>]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> In the above image, color 1 is blue, color 8 is yellow, and color 3 is green.
-The furthest two houses with different colors are house 0 and house 4.
-House 0 has color 1, and house 4 has color 3. The distance between them is abs(0 - 4) = 4.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> colors = [<u><strong>0</strong></u>,<strong><u>1</u></strong>]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The furthest two houses with different colors are house 0 and house 1.
-House 0 has color 0, and house 1 has color 1. The distance between them is abs(0 - 1) = 1.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n ==&nbsp;colors.length</code></li>
-	<li><code>2 &lt;= n &lt;= 100</code></li>
-	<li><code>0 &lt;= colors[i] &lt;= 100</code></li>
-	<li>Test data are generated such that <strong>at least</strong> two houses have different colors.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The constraints are small. Can you try the combination of every two houses?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Greedily, the maximum distance will come from either the pair of the leftmost house and possibly some house on the right with a different color, or the pair of the rightmost house and possibly some house on the left with a different color.
-</details>
diff --git a/problems/two-out-of-three/README.md b/problems/two-out-of-three/README.md
deleted file mode 100644
index 176e64f08..000000000
--- a/problems/two-out-of-three/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-subarrays-with-more-ones-than-zeros "Count Subarrays With More Ones Than Zeros")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-operations-to-make-a-uni-value-grid "Minimum Operations to Make a Uni-Value Grid")
-
-## [2032. Two Out of Three (Easy)](https://leetcode.com/problems/two-out-of-three "至少在两个数组中出现的值")
-
-Given three integer arrays <code>nums1</code>, <code>nums2</code>, and <code>nums3</code>, return <em>a <strong>distinct</strong> array containing all the values that are present in <strong>at least two</strong> out of the three arrays. You may return the values in <strong>any</strong> order</em>.
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,1,3,2], nums2 = [2,3], nums3 = [3]
-<strong>Output:</strong> [3,2]
-<strong>Explanation:</strong> The values that are present in at least two arrays are:
-- 3, in all three arrays.
-- 2, in nums1 and nums2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [3,1], nums2 = [2,3], nums3 = [1,2]
-<strong>Output:</strong> [2,3,1]
-<strong>Explanation:</strong> The values that are present in at least two arrays are:
-- 2, in nums2 and nums3.
-- 3, in nums1 and nums2.
-- 1, in nums1 and nums3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,2,2], nums2 = [4,3,3], nums3 = [5]
-<strong>Output:</strong> []
-<strong>Explanation:</strong> No value is present in at least two arrays.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length, nums3.length &lt;= 100</code></li>
-	<li><code>1 &lt;= nums1[i], nums2[j], nums3[k] &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What data structure can we use to help us quickly find whether an element belongs in an array?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can we count the frequencies of the elements in each array?
-</details>
diff --git a/problems/two-sum-bsts/README.md b/problems/two-sum-bsts/README.md
deleted file mode 100644
index a8e816200..000000000
--- a/problems/two-sum-bsts/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../intersection-of-three-sorted-arrays "Intersection of Three Sorted Arrays")
-　　　　　　　　　　　　　　　　
-[Next >](../stepping-numbers "Stepping Numbers")
-
-## [1214. Two Sum BSTs (Medium)](https://leetcode.com/problems/two-sum-bsts "查找两棵二叉搜索树之和")
-
-<p>Given two binary search trees, return <code>True</code>&nbsp;if and only if there is a node in the first tree and a node in the second tree whose values&nbsp;sum up to a given integer&nbsp;<code>target</code>.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/05/31/1368_1_a2.png" style="width: 150px; height: 140px;" /><img alt="" src="https://assets.leetcode.com/uploads/2019/05/31/1368_1_b.png" style="width: 150px; height: 136px;" /></strong></p>
-
-<pre>
-<strong>Input: </strong>root1 = <span id="example-input-1-1">[2,1,4]</span>, root2 = <span id="example-input-1-2">[1,0,3]</span>, target = <span id="example-input-1-3">5</span>
-<strong>Output: </strong><span id="example-output-1">true</span>
-<b>Explanation: </b>2 and 3 sum up to 5.
-</pre>
-
-<div>
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/05/31/1368_2_a.png" style="width: 150px; height: 137px;" /><img alt="" src="https://assets.leetcode.com/uploads/2019/05/31/1368_2_b.png" style="width: 150px; height: 168px;" /></strong></p>
-
-<pre>
-<strong>Input: </strong>root1 = <span id="example-input-2-1">[0,-10,10]</span>, root2 = <span id="example-input-2-2">[5,1,7,0,2]</span>, target = <span id="example-input-2-3">18</span>
-<strong>Output: </strong><span id="example-output-2">false</span></pre>
-</div>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li>Each tree has at most <code>5000</code> nodes.</li>
-	<li><code>-10^9 &lt;= target, node.val &lt;= 10^9</code></li>
-</ol>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Two Sum IV - Input is a BST](../two-sum-iv-input-is-a-bst) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-How can you reduce this problem to the classical Two Sum problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Do an in-order traversal of each tree to convert them to sorted arrays.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Solve the classical Two Sum problem.
-</details>
diff --git a/problems/two-sum-ii-input-array-is-sorted/README.md b/problems/two-sum-ii-input-array-is-sorted/README.md
deleted file mode 100644
index 40afa44a6..000000000
--- a/problems/two-sum-ii-input-array-is-sorted/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fraction-to-recurring-decimal "Fraction to Recurring Decimal")
-　　　　　　　　　　　　　　　　
-[Next >](../excel-sheet-column-title "Excel Sheet Column Title")
-
-## [167. Two Sum II - Input array is sorted (Easy)](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted "两数之和 II - 输入有序数组")
-
-<p>Given an array of integers <code>numbers</code> that is already <strong><em>sorted in non-decreasing order</em></strong>, find two numbers such that they add up to a specific <code>target</code> number.</p>
-
-<p>Return<em> the indices of the two numbers (<strong>1-indexed</strong>) as an integer array </em><code>answer</code><em> of size </em><code>2</code><em>, where </em><code>1 &lt;= answer[0] &lt; answer[1] &lt;= numbers.length</code>.</p>
-
-<p>The tests are generated such that there is <strong>exactly one solution</strong>. You <strong>may not</strong> use the same element twice.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> numbers = [2,7,11,15], target = 9
-<strong>Output:</strong> [1,2]
-<strong>Explanation:</strong> The sum of 2 and 7 is 9. Therefore index1 = 1, index2 = 2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> numbers = [2,3,4], target = 6
-<strong>Output:</strong> [1,3]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> numbers = [-1,0], target = -1
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= numbers.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>-1000 &lt;= numbers[i] &lt;= 1000</code></li>
-	<li><code>numbers</code> is sorted in <strong>non-decreasing order</strong>.</li>
-	<li><code>-1000 &lt;= target &lt;= 1000</code></li>
-	<li>The tests are generated such that there is <strong>exactly one solution</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Two Sum](../two-sum) (Easy)
-  1. [Two Sum IV - Input is a BST](../two-sum-iv-input-is-a-bst) (Easy)
-  1. [Two Sum Less Than K](../two-sum-less-than-k) (Easy)
diff --git a/problems/two-sum-ii-input-array-is-sorted/two_sum_ii_input_array_is_sorted.go b/problems/two-sum-ii-input-array-is-sorted/two_sum_ii_input_array_is_sorted.go
deleted file mode 100644
index 75f571c5a..000000000
--- a/problems/two-sum-ii-input-array-is-sorted/two_sum_ii_input_array_is_sorted.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package problem167
-
-func twoSum(numbers []int, target int) []int {
-	s := 0
-	l := len(numbers) - 1
-	for s < l {
-		r := numbers[s] + numbers[l]
-		if r == target {
-			return []int{s + 1, l + 1}
-		} else if r < target {
-			s++
-		} else {
-			l--
-		}
-	}
-	return nil
-}
diff --git a/problems/two-sum-ii-input-array-is-sorted/two_sum_ii_input_array_is_sorted_test.go b/problems/two-sum-ii-input-array-is-sorted/two_sum_ii_input_array_is_sorted_test.go
deleted file mode 100644
index 432b299db..000000000
--- a/problems/two-sum-ii-input-array-is-sorted/two_sum_ii_input_array_is_sorted_test.go
+++ /dev/null
@@ -1,44 +0,0 @@
-package problem167
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	nums   []int
-	target int
-	want   []int
-}
-
-func TestTwoSum(t *testing.T) {
-	tests := [...]testType{
-		{
-			nums:   []int{2, 7, 11, 15},
-			target: 9,
-			want:   []int{1, 2},
-		},
-		{
-			nums:   []int{2, 7, 11, 15},
-			target: 10,
-			want:   nil,
-		},
-		{
-			nums:   []int{1, 3, 5, 7, 9, 12},
-			target: 16,
-			want:   []int{4, 5},
-		},
-		{
-			nums:   []int{1, 2, 3, 4},
-			target: 6,
-			want:   []int{2, 4},
-		},
-	}
-
-	for _, tt := range tests {
-		got := twoSum(tt.nums, tt.target)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.nums, got, tt.want)
-		}
-	}
-}
diff --git a/problems/two-sum-iii-data-structure-design/README.md b/problems/two-sum-iii-data-structure-design/README.md
deleted file mode 100644
index c212c4fd5..000000000
--- a/problems/two-sum-iii-data-structure-design/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../majority-element "Majority Element")
-　　　　　　　　　　　　　　　　
-[Next >](../excel-sheet-column-number "Excel Sheet Column Number")
-
-## [170. Two Sum III - Data structure design (Easy)](https://leetcode.com/problems/two-sum-iii-data-structure-design "两数之和 III - 数据结构设计")
-
-<p>Design and implement a TwoSum class. It should support the following operations: <code>add</code> and <code>find</code>.</p>
-
-<p><code>add</code> - Add the number to an internal data structure.<br />
-<code>find</code> - Find if there exists any pair of numbers which sum is equal to the value.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-add(1); add(3); add(5);
-find(4) -&gt; true
-find(7) -&gt; false
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-add(3); add(1); add(2);
-find(3) -&gt; true
-find(6) -&gt; false</pre>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Data Stream](../../tag/data-stream/README.md)]
-
-### Similar Questions
-  1. [Two Sum](../two-sum) (Easy)
-  1. [Unique Word Abbreviation](../unique-word-abbreviation) (Medium)
-  1. [Two Sum IV - Input is a BST](../two-sum-iv-input-is-a-bst) (Easy)
diff --git a/problems/two-sum-iii-data-structure-design/two_sum_iii_data_structure_design.go b/problems/two-sum-iii-data-structure-design/two_sum_iii_data_structure_design.go
deleted file mode 100644
index 4aeecf401..000000000
--- a/problems/two-sum-iii-data-structure-design/two_sum_iii_data_structure_design.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem170
diff --git a/problems/two-sum-iii-data-structure-design/two_sum_iii_data_structure_design_test.go b/problems/two-sum-iii-data-structure-design/two_sum_iii_data_structure_design_test.go
deleted file mode 100644
index 4aeecf401..000000000
--- a/problems/two-sum-iii-data-structure-design/two_sum_iii_data_structure_design_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem170
diff --git a/problems/two-sum-iv-input-is-a-bst/README.md b/problems/two-sum-iv-input-is-a-bst/README.md
deleted file mode 100644
index 098f7ab54..000000000
--- a/problems/two-sum-iv-input-is-a-bst/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-duplicate-subtrees "Find Duplicate Subtrees")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-binary-tree "Maximum Binary Tree")
-
-## [653. Two Sum IV - Input is a BST (Easy)](https://leetcode.com/problems/two-sum-iv-input-is-a-bst "两数之和 IV - 输入 BST")
-
-<p>Given the <code>root</code> of a Binary Search Tree and a target number <code>k</code>, return <em><code>true</code> if there exist two elements in the BST such that their sum is equal to the given target</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/sum_tree_1.jpg" style="width: 562px; height: 322px;" />
-<pre>
-<strong>Input:</strong> root = [5,3,6,2,4,null,7], k = 9
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/sum_tree_2.jpg" style="width: 562px; height: 322px;" />
-<pre>
-<strong>Input:</strong> root = [5,3,6,2,4,null,7], k = 28
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [2,1,3], k = 4
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [2,1,3], k = 1
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> root = [2,1,3], k = 3
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-10<sup>4</sup>&nbsp;&lt;= Node.val &lt;= 10<sup>4</sup></code></li>
-	<li><code>root</code> is guaranteed to be a <strong>valid</strong> binary search tree.</li>
-	<li><code>-10<sup>5</sup>&nbsp;&lt;= k &lt;= 10<sup>5</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Two Sum](../two-sum) (Easy)
-  1. [Two Sum II - Input Array Is Sorted](../two-sum-ii-input-array-is-sorted) (Easy)
-  1. [Two Sum III - Data structure design](../two-sum-iii-data-structure-design) (Easy)
-  1. [Two Sum BSTs](../two-sum-bsts) (Medium)
diff --git a/problems/two-sum-iv-input-is-a-bst/two_sum_iv_input_is_a_bst.go b/problems/two-sum-iv-input-is-a-bst/two_sum_iv_input_is_a_bst.go
deleted file mode 100644
index 12abcf428..000000000
--- a/problems/two-sum-iv-input-is-a-bst/two_sum_iv_input_is_a_bst.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem653
diff --git a/problems/two-sum-iv-input-is-a-bst/two_sum_iv_input_is_a_bst_test.go b/problems/two-sum-iv-input-is-a-bst/two_sum_iv_input_is_a_bst_test.go
deleted file mode 100644
index 12abcf428..000000000
--- a/problems/two-sum-iv-input-is-a-bst/two_sum_iv_input_is_a_bst_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem653
diff --git a/problems/two-sum-less-than-k/README.md b/problems/two-sum-less-than-k/README.md
deleted file mode 100644
index 396a01979..000000000
--- a/problems/two-sum-less-than-k/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unpopular-books "Unpopular Books")
-　　　　　　　　　　　　　　　　
-[Next >](../find-k-length-substrings-with-no-repeated-characters "Find K-Length Substrings With No Repeated Characters")
-
-## [1099. Two Sum Less Than K (Easy)](https://leetcode.com/problems/two-sum-less-than-k "小于 K 的两数之和")
-
-<p>Given an array <code>A</code> of integers and&nbsp;integer <code>K</code>, return the maximum <code>S</code> such that there exists <code>i &lt; j</code> with <code>A[i] + A[j] = S</code> and <code>S &lt; K</code>. If no <code>i, j</code> exist satisfying this equation, return -1.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>A = <span id="example-input-1-1">[34,23,1,24,75,33,54,8]</span>, K = <span id="example-input-1-2">60</span>
-<strong>Output: </strong><span id="example-output-1">58</span>
-<strong>Explanation: </strong>
-We can use 34 and 24 to sum 58 which is less than 60.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>A = <span id="example-input-2-1">[10,20,30]</span>, K = <span id="example-input-2-2">15</span>
-<strong>Output: </strong><span id="example-output-2">-1</span>
-<strong>Explanation: </strong>
-In this case it&#39;s not possible to get a pair sum less that 15.
-</pre>
-
-<p>&nbsp;</p>
-
-<p><strong>Note:</strong></p>
-
-<ol>
-	<li><code>1 &lt;= A.length &lt;= 100</code></li>
-	<li><code>1 &lt;= A[i] &lt;= 1000</code></li>
-	<li><code>1 &lt;= K &lt;= 2000</code></li>
-</ol>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Two Sum](../two-sum) (Easy)
-  1. [Two Sum II - Input Array Is Sorted](../two-sum-ii-input-array-is-sorted) (Easy)
-  1. [3Sum Smaller](../3sum-smaller) (Medium)
-  1. [Subarray Product Less Than K](../subarray-product-less-than-k) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if we have the array sorted?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Loop the array and get the value A[i] then we need to find a value A[j] such that A[i] + A[j] < K  which means A[j] < K - A[i]. In order to do that we can find that value with a binary search.
-</details>
diff --git a/problems/two-sum/README.md b/problems/two-sum/README.md
deleted file mode 100644
index aa409a146..000000000
--- a/problems/two-sum/README.md
+++ /dev/null
@@ -1,83 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-< Previous
-　　　　　　　　　　　　　　　　
-[Next >](../add-two-numbers "Add Two Numbers")
-
-## [1. Two Sum (Easy)](https://leetcode.com/problems/two-sum "两数之和")
-
-<p>Given an array of integers <code>nums</code>&nbsp;and an integer <code>target</code>, return <em>indices of the two numbers such that they add up to <code>target</code></em>.</p>
-
-<p>You may assume that each input would have <strong><em>exactly</em> one solution</strong>, and you may not use the <em>same</em> element twice.</p>
-
-<p>You can return the answer in any order.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,7,11,15], target = 9
-<strong>Output:</strong> [0,1]
-<strong>Explanation:</strong> Because nums[0] + nums[1] == 9, we return [0, 1].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,4], target = 6
-<strong>Output:</strong> [1,2]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,3], target = 6
-<strong>Output:</strong> [0,1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>-10<sup>9</sup> &lt;= target &lt;= 10<sup>9</sup></code></li>
-	<li><strong>Only one valid answer exists.</strong></li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow-up:&nbsp;</strong>Can you come up with an algorithm that is less than&nbsp;<code>O(n<sup>2</sup>)&nbsp;</code>time complexity?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Similar Questions
-  1. [3Sum](../3sum) (Medium)
-  1. [4Sum](../4sum) (Medium)
-  1. [Two Sum II - Input Array Is Sorted](../two-sum-ii-input-array-is-sorted) (Medium)
-  1. [Two Sum III - Data structure design](../two-sum-iii-data-structure-design) (Easy)
-  1. [Subarray Sum Equals K](../subarray-sum-equals-k) (Medium)
-  1. [Two Sum IV - Input is a BST](../two-sum-iv-input-is-a-bst) (Easy)
-  1. [Two Sum Less Than K](../two-sum-less-than-k) (Easy)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-A really brute force way would be to search for all possible pairs of numbers but that would be too slow. Again, it's best to try out brute force solutions for just for completeness. It is from these brute force solutions that you can come up with optimizations.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-So, if we fix one of the numbers, say <pre>x</pre>, we have to scan the entire array to find the next number <pre>y</pre> which is <pre>value - x</pre> where value is the input parameter. Can we change our array somehow so that this search becomes faster?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The second train of thought is, without changing the array, can we use additional space somehow? Like maybe a hash map to speed up the search?
-</details>
diff --git a/problems/two-sum/two_sum.go b/problems/two-sum/two_sum.go
deleted file mode 100644
index 0ef6d366e..000000000
--- a/problems/two-sum/two_sum.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem1
-
-func twoSum(nums []int, target int) []int {
-	m := make(map[int]int)
-	for j, v := range nums {
-		if i, ok := m[target-v]; ok {
-			return []int{i, j}
-		}
-		m[v] = j
-	}
-	return nil
-}
diff --git a/problems/two-sum/two_sum_test.go b/problems/two-sum/two_sum_test.go
deleted file mode 100644
index 1236c35d9..000000000
--- a/problems/two-sum/two_sum_test.go
+++ /dev/null
@@ -1,38 +0,0 @@
-package problem1
-
-import (
-	"reflect"
-	"testing"
-)
-
-type testType struct {
-	nums   []int
-	target int
-	want   []int
-}
-
-func TestTwoSum(t *testing.T) {
-	tests := [...]testType{
-		{
-			nums:   []int{2, 7, 11, 15},
-			target: 9,
-			want:   []int{0, 1},
-		},
-		{
-			nums:   []int{2, 7, 11, 15},
-			target: 10,
-			want:   nil,
-		},
-		{
-			nums:   []int{1, 2, 3, 4},
-			target: 5,
-			want:   []int{1, 2},
-		},
-	}
-	for _, tt := range tests {
-		got := twoSum(tt.nums, tt.target)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.nums, got, tt.want)
-		}
-	}
-}
diff --git a/problems/ugly-number-ii/README.md b/problems/ugly-number-ii/README.md
deleted file mode 100644
index 43eeab7b8..000000000
--- a/problems/ugly-number-ii/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../ugly-number "Ugly Number")
-　　　　　　　　　　　　　　　　
-[Next >](../paint-house-ii "Paint House II")
-
-## [264. Ugly Number II (Medium)](https://leetcode.com/problems/ugly-number-ii "丑数 II")
-
-<p>An <strong>ugly number</strong> is a positive integer whose prime factors are limited to <code>2</code>, <code>3</code>, and <code>5</code>.</p>
-
-<p>Given an integer <code>n</code>, return <em>the</em> <code>n<sup>th</sup></code> <em><strong>ugly number</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 10
-<strong>Output:</strong> 12
-<strong>Explanation:</strong> [1, 2, 3, 4, 5, 6, 8, 9, 10, 12] is the sequence of the first 10 ugly numbers.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> 1 has no prime factors, therefore all of its prime factors are limited to 2, 3, and 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1690</code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Heap (Priority Queue)](../../tag/heap-priority-queue/README.md)]
-
-### Similar Questions
-  1. [Merge k Sorted Lists](../merge-k-sorted-lists) (Hard)
-  1. [Count Primes](../count-primes) (Medium)
-  1. [Ugly Number](../ugly-number) (Easy)
-  1. [Perfect Squares](../perfect-squares) (Medium)
-  1. [Super Ugly Number](../super-ugly-number) (Medium)
-  1. [Ugly Number III](../ugly-number-iii) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The naive approach is to call <code>isUgly</code> for every number until you reach the n<sup>th</sup> one. Most numbers are <i>not</i> ugly. Try to focus your effort on generating only the ugly ones.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-An ugly number must be multiplied by either 2, 3, or 5 from a smaller ugly number.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The key is how to maintain the order of the ugly numbers. Try a similar approach of merging from three sorted lists: L<sub>1</sub>, L<sub>2</sub>, and L<sub>3</sub>.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Assume you have U<sub>k</sub>, the k<sup>th</sup> ugly number. Then U<sub>k+1</sub> must be Min(L<sub>1</sub> * 2, L<sub>2</sub> * 3, L<sub>3</sub> * 5).
-</details>
diff --git a/problems/ugly-number-ii/ugly_number_ii.go b/problems/ugly-number-ii/ugly_number_ii.go
deleted file mode 100644
index 652909643..000000000
--- a/problems/ugly-number-ii/ugly_number_ii.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem264
-
-func nthUglyNumber(n int) int {
-	ans, idx := make([]int, n), [3]int{}
-	ans[0] = 1
-	for i := 1; i < n; i++ {
-		for j, n := range [...]int{2, 3, 5} {
-			if ans[idx[j]]*n <= ans[i-1] {
-				idx[j]++
-			}
-			if num := ans[idx[j]] * n; j == 0 {
-				ans[i] = num
-			} else if ans[i] > num {
-				ans[i] = num
-			}
-		}
-	}
-	return ans[n-1]
-}
diff --git a/problems/ugly-number-ii/ugly_number_ii_test.go b/problems/ugly-number-ii/ugly_number_ii_test.go
deleted file mode 100644
index 45cf5fd00..000000000
--- a/problems/ugly-number-ii/ugly_number_ii_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem264
-
-import "testing"
-
-type testType struct {
-	in   int
-	want int
-}
-
-func TestNthUglyNumber(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   10,
-			want: 12,
-		},
-		{
-			in:   9,
-			want: 10,
-		},
-		{
-			in:   60,
-			want: 384,
-		},
-		{
-			in:   90,
-			want: 1152,
-		},
-		{
-			in:   1,
-			want: 1,
-		},
-	}
-	for _, tt := range tests {
-		got := nthUglyNumber(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/ugly-number-iii/README.md b/problems/ugly-number-iii/README.md
deleted file mode 100644
index 0790cc0c7..000000000
--- a/problems/ugly-number-iii/README.md
+++ /dev/null
@@ -1,73 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-absolute-difference "Minimum Absolute Difference")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-string-with-swaps "Smallest String With Swaps")
-
-## [1201. Ugly Number III (Medium)](https://leetcode.com/problems/ugly-number-iii "丑数 III")
-
-<p>An <strong>ugly number</strong> is a positive integer that is divisible by <code>a</code>, <code>b</code>, or <code>c</code>.</p>
-
-<p>Given four integers <code>n</code>, <code>a</code>, <code>b</code>, and <code>c</code>, return the <code>n<sup>th</sup></code> <strong>ugly number</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 3, a = 2, b = 3, c = 5
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The ugly numbers are 2, 3, 4, 5, 6, 8, 9, 10... The 3rd is 4.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, a = 2, b = 3, c = 4
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The ugly numbers are 2, 3, 4, 6, 8, 9, 10, 12... The 4th is 6.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, a = 2, b = 11, c = 13
-<strong>Output:</strong> 10
-<strong>Explanation:</strong> The ugly numbers are 2, 4, 6, 8, 10, 11, 12, 13... The 5th is 10.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1000000000, a = 2, b = 217983653, c = 336916467
-<strong>Output:</strong> 1999999984
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n, a, b, c &lt;= 10<sup>9</sup></code></li>
-	<li><code>1 &lt;= a * b * c &lt;= 10<sup>18</sup></code></li>
-	<li>It is guaranteed that the result will be in range <code>[1, 2 * 10<sup>9</sup>]</code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Number Theory](../../tag/number-theory/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Write a function f(k) to determine how many ugly numbers smaller than k. As f(k) is non-decreasing, try binary search.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Find all ugly numbers in [1, LCM(a, b, c)] (LCM is Least Common Multiple). Use inclusion-exclusion principle to expand the result.
-</details>
diff --git a/problems/ugly-number/README.md b/problems/ugly-number/README.md
deleted file mode 100644
index 1a30c5d48..000000000
--- a/problems/ugly-number/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../trips-and-users "Trips and Users")
-　　　　　　　　　　　　　　　　
-[Next >](../ugly-number-ii "Ugly Number II")
-
-## [263. Ugly Number (Easy)](https://leetcode.com/problems/ugly-number "丑数")
-
-<p>An <strong>ugly number</strong> is a positive integer whose prime factors are limited to <code>2</code>, <code>3</code>, and <code>5</code>.</p>
-
-<p>Given an integer <code>n</code>, return <code>true</code> <em>if</em> <code>n</code> <em>is an <strong>ugly number</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 6
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 6 = 2 &times; 3</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 8
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 8 = 2 &times; 2 &times; 2
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 14
-<strong>Output:</strong> false
-<strong>Explanation:</strong> 14 is not ugly since it includes the prime factor 7.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> true
-<strong>Explanation:</strong> 1 has no prime factors, therefore all of its prime factors are limited to 2, 3, and 5.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>-2<sup>31</sup> &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-
-### Similar Questions
-  1. [Happy Number](../happy-number) (Easy)
-  1. [Count Primes](../count-primes) (Easy)
-  1. [Ugly Number II](../ugly-number-ii) (Medium)
diff --git a/problems/ugly-number/ugly_number.go b/problems/ugly-number/ugly_number.go
deleted file mode 100644
index 670d391cd..000000000
--- a/problems/ugly-number/ugly_number.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package problem263
-
-func isUgly(num int) bool {
-	if num < 1 {
-		return false
-	}
-	for _, n := range [...]int{2, 3, 5} {
-		for num%n == 0 {
-			num /= n
-		}
-	}
-	return num == 1
-}
diff --git a/problems/ugly-number/ugly_number_test.go b/problems/ugly-number/ugly_number_test.go
deleted file mode 100644
index 0d74ba9dc..000000000
--- a/problems/ugly-number/ugly_number_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem263
-
-import "testing"
-
-type testType struct {
-	in   int
-	want bool
-}
-
-func TestIsUgly(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   1,
-			want: true,
-		},
-		{
-			in:   6,
-			want: true,
-		},
-		{
-			in:   8,
-			want: true,
-		},
-		{
-			in:   14,
-			want: false,
-		},
-		{
-			in:   0,
-			want: false,
-		},
-		{
-			in:   -30,
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isUgly(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/uncommon-words-from-two-sentences/README.md b/problems/uncommon-words-from-two-sentences/README.md
deleted file mode 100644
index f4921ce8a..000000000
--- a/problems/uncommon-words-from-two-sentences/README.md
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../projection-area-of-3d-shapes "Projection Area of 3D Shapes")
-　　　　　　　　　　　　　　　　
-[Next >](../spiral-matrix-iii "Spiral Matrix III")
-
-## [884. Uncommon Words from Two Sentences (Easy)](https://leetcode.com/problems/uncommon-words-from-two-sentences "两句话中的不常见单词")
-
-<p>A <strong>sentence</strong> is a string of single-space separated words where each word consists only of lowercase letters.</p>
-
-<p>A word is <strong>uncommon</strong> if it appears exactly once in one of the sentences, and <strong>does not appear</strong> in the other sentence.</p>
-
-<p>Given two <strong>sentences</strong> <code>s1</code> and <code>s2</code>, return <em>a list of all the <strong>uncommon words</strong></em>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s1 = "this apple is sweet", s2 = "this apple is sour"
-<strong>Output:</strong> ["sweet","sour"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s1 = "apple apple", s2 = "banana"
-<strong>Output:</strong> ["banana"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s1.length, s2.length &lt;= 200</code></li>
-	<li><code>s1</code> and <code>s2</code> consist of lowercase English letters and spaces.</li>
-	<li><code>s1</code> and <code>s2</code> do not have leading or trailing spaces.</li>
-	<li>All the words in <code>s1</code> and <code>s2</code> are separated by a single space.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/uncommon-words-from-two-sentences/uncommon_words_from_two_sentences.go b/problems/uncommon-words-from-two-sentences/uncommon_words_from_two_sentences.go
deleted file mode 100644
index ce7023d52..000000000
--- a/problems/uncommon-words-from-two-sentences/uncommon_words_from_two_sentences.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem884
diff --git a/problems/uncommon-words-from-two-sentences/uncommon_words_from_two_sentences_test.go b/problems/uncommon-words-from-two-sentences/uncommon_words_from_two_sentences_test.go
deleted file mode 100644
index ce7023d52..000000000
--- a/problems/uncommon-words-from-two-sentences/uncommon_words_from_two_sentences_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem884
diff --git a/problems/uncrossed-lines/README.md b/problems/uncrossed-lines/README.md
deleted file mode 100644
index f53f4158e..000000000
--- a/problems/uncrossed-lines/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../coloring-a-border "Coloring A Border")
-　　　　　　　　　　　　　　　　
-[Next >](../escape-a-large-maze "Escape a Large Maze")
-
-## [1035. Uncrossed Lines (Medium)](https://leetcode.com/problems/uncrossed-lines "不相交的线")
-
-<p>You are given two integer arrays <code>nums1</code> and <code>nums2</code>. We write the integers of <code>nums1</code> and <code>nums2</code> (in the order they are given) on two separate horizontal lines.</p>
-
-<p>We may draw connecting lines: a straight line connecting two numbers <code>nums1[i]</code> and <code>nums2[j]</code> such that:</p>
-
-<ul>
-	<li><code>nums1[i] == nums2[j]</code>, and</li>
-	<li>the line we draw does not intersect any other connecting (non-horizontal) line.</li>
-</ul>
-
-<p>Note that a connecting line cannot intersect even at the endpoints (i.e., each number can only belong to one connecting line).</p>
-
-<p>Return <em>the maximum number of connecting lines we can draw in this way</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/04/26/142.png" style="width: 400px; height: 286px;" />
-<pre>
-<strong>Input:</strong> nums1 = [1,4,2], nums2 = [1,2,4]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We can draw 2 uncrossed lines as in the diagram.
-We cannot draw 3 uncrossed lines, because the line from nums1[1] = 4 to nums2[2] = 4 will intersect the line from nums1[2]=2 to nums2[1]=2.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [2,5,1,2,5], nums2 = [10,5,2,1,5,2]
-<strong>Output:</strong> 3
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums1 = [1,3,7,1,7,5], nums2 = [1,9,2,5,1]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 500</code></li>
-	<li><code>1 &lt;= nums1[i], nums2[j] &lt;= 2000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Edit Distance](../edit-distance) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Think dynamic programming.  Given an oracle dp(i,j) that tells us how many lines A[i:], B[j:]  [the sequence A[i], A[i+1], ... and B[j], B[j+1], ...] are uncrossed, can we write this as a recursion?
-</details>
diff --git a/problems/uncrossed-lines/uncrossed_lines.go b/problems/uncrossed-lines/uncrossed_lines.go
deleted file mode 100644
index b2fb26c6a..000000000
--- a/problems/uncrossed-lines/uncrossed_lines.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package problem1035
-
-func maxUncrossedLines(A []int, B []int) int {
-	m, n := len(A), len(B)
-	dp := make([][]int, m+1)
-	dp[0] = make([]int, n+1)
-	for i := 1; i <= m; i++ {
-		dp[i] = make([]int, n+1)
-		for j := 1; j <= n; j++ {
-			if A[i-1] == B[j-1] {
-				dp[i][j] = 1 + dp[i-1][j-1]
-			} else {
-				dp[i][j] = max(dp[i][j-1], dp[i-1][j])
-			}
-		}
-	}
-	return dp[m][n]
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/unique-binary-search-trees-ii/README.md b/problems/unique-binary-search-trees-ii/README.md
deleted file mode 100644
index 8fcad49b8..000000000
--- a/problems/unique-binary-search-trees-ii/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-inorder-traversal "Binary Tree Inorder Traversal")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-binary-search-trees "Unique Binary Search Trees")
-
-## [95. Unique Binary Search Trees II (Medium)](https://leetcode.com/problems/unique-binary-search-trees-ii "不同的二叉搜索树 II")
-
-<p>Given an integer <code>n</code>, return <em>all the structurally unique <strong>BST&#39;</strong>s (binary search trees), which has exactly </em><code>n</code><em> nodes of unique values from</em> <code>1</code> <em>to</em> <code>n</code>. Return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/uniquebstn3.jpg" style="width: 600px; height: 148px;" />
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> [[1,null,2,null,3],[1,null,3,2],[2,1,3],[3,1,null,null,2],[3,2,null,1]]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> [[1]]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 8</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Unique Binary Search Trees](../unique-binary-search-trees) (Medium)
-  1. [Different Ways to Add Parentheses](../different-ways-to-add-parentheses) (Medium)
diff --git a/problems/unique-binary-search-trees-ii/unique_binary_search_trees_ii.go b/problems/unique-binary-search-trees-ii/unique_binary_search_trees_ii.go
deleted file mode 100644
index be692e191..000000000
--- a/problems/unique-binary-search-trees-ii/unique_binary_search_trees_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem95
diff --git a/problems/unique-binary-search-trees-ii/unique_binary_search_trees_ii_test.go b/problems/unique-binary-search-trees-ii/unique_binary_search_trees_ii_test.go
deleted file mode 100644
index be692e191..000000000
--- a/problems/unique-binary-search-trees-ii/unique_binary_search_trees_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem95
diff --git a/problems/unique-binary-search-trees/README.md b/problems/unique-binary-search-trees/README.md
deleted file mode 100644
index a4a346d4b..000000000
--- a/problems/unique-binary-search-trees/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-binary-search-trees-ii "Unique Binary Search Trees II")
-　　　　　　　　　　　　　　　　
-[Next >](../interleaving-string "Interleaving String")
-
-## [96. Unique Binary Search Trees (Medium)](https://leetcode.com/problems/unique-binary-search-trees "不同的二叉搜索树")
-
-<p>Given an integer <code>n</code>, return <em>the number of structurally unique <strong>BST&#39;</strong>s (binary search trees) which has exactly </em><code>n</code><em> nodes of unique values from</em> <code>1</code> <em>to</em> <code>n</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/uniquebstn3.jpg" style="width: 600px; height: 148px;" />
-<pre>
-<strong>Input:</strong> n = 3
-<strong>Output:</strong> 5
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 1
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 19</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Unique Binary Search Trees II](../unique-binary-search-trees-ii) (Medium)
diff --git a/problems/unique-binary-search-trees/unique_binary_search_trees.go b/problems/unique-binary-search-trees/unique_binary_search_trees.go
deleted file mode 100644
index 846b407dd..000000000
--- a/problems/unique-binary-search-trees/unique_binary_search_trees.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem96
diff --git a/problems/unique-binary-search-trees/unique_binary_search_trees_test.go b/problems/unique-binary-search-trees/unique_binary_search_trees_test.go
deleted file mode 100644
index 846b407dd..000000000
--- a/problems/unique-binary-search-trees/unique_binary_search_trees_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem96
diff --git a/problems/unique-email-addresses/README.md b/problems/unique-email-addresses/README.md
deleted file mode 100644
index 755ffc50b..000000000
--- a/problems/unique-email-addresses/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimize-malware-spread-ii "Minimize Malware Spread II")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-subarrays-with-sum "Binary Subarrays With Sum")
-
-## [929. Unique Email Addresses (Easy)](https://leetcode.com/problems/unique-email-addresses "独特的电子邮件地址")
-
-<p>Every <strong>valid email</strong> consists of a <strong>local name</strong> and a <strong>domain name</strong>, separated by the <code>&#39;@&#39;</code> sign. Besides lowercase letters, the email may contain one or more <code>&#39;.&#39;</code> or <code>&#39;+&#39;</code>.</p>
-
-<ul>
-	<li>For example, in <code>&quot;alice@leetcode.com&quot;</code>, <code>&quot;alice&quot;</code> is the <strong>local name</strong>, and <code>&quot;leetcode.com&quot;</code> is the <strong>domain name</strong>.</li>
-</ul>
-
-<p>If you add periods <code>&#39;.&#39;</code> between some characters in the <strong>local name</strong> part of an email address, mail sent there will be forwarded to the same address without dots in the local name. Note that this rule <strong>does not apply</strong> to <strong>domain names</strong>.</p>
-
-<ul>
-	<li>For example, <code>&quot;alice.z@leetcode.com&quot;</code> and <code>&quot;alicez@leetcode.com&quot;</code> forward to the same email address.</li>
-</ul>
-
-<p>If you add a plus <code>&#39;+&#39;</code> in the <strong>local name</strong>, everything after the first plus sign <strong>will be ignored</strong>. This allows certain emails to be filtered. Note that this rule <strong>does not apply</strong> to <strong>domain names</strong>.</p>
-
-<ul>
-	<li>For example, <code>&quot;m.y+name@email.com&quot;</code> will be forwarded to <code>&quot;my@email.com&quot;</code>.</li>
-</ul>
-
-<p>It is possible to use both of these rules at the same time.</p>
-
-<p>Given an array of strings <code>emails</code> where we send one email to each <code>email[i]</code>, return <em>the number of different addresses that actually receive mails</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> emails = [&quot;test.email+alex@leetcode.com&quot;,&quot;test.e.mail+bob.cathy@leetcode.com&quot;,&quot;testemail+david@lee.tcode.com&quot;]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> &quot;testemail@leetcode.com&quot; and &quot;testemail@lee.tcode.com&quot; actually receive mails.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> emails = [&quot;a@leetcode.com&quot;,&quot;b@leetcode.com&quot;,&quot;c@leetcode.com&quot;]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= emails.length &lt;= 100</code></li>
-	<li><code>1 &lt;= emails[i].length &lt;= 100</code></li>
-	<li><code>email[i]</code> consist of lowercase English letters, <code>&#39;+&#39;</code>, <code>&#39;.&#39;</code> and <code>&#39;@&#39;</code>.</li>
-	<li>Each <code>emails[i]</code> contains exactly one <code>&#39;@&#39;</code> character.</li>
-	<li>All local and domain names are non-empty.</li>
-	<li>Local names do not start with a <code>&#39;+&#39;</code> character.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/unique-email-addresses/unique_email_addresses.go b/problems/unique-email-addresses/unique_email_addresses.go
deleted file mode 100644
index aaa67407c..000000000
--- a/problems/unique-email-addresses/unique_email_addresses.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem929
-
-import "strings"
-
-func numUniqueEmails(emails []string) int {
-	m := make(map[string]bool)
-	count := 0
-	for _, email := range emails {
-		plusIndex := strings.Index(email, "+")
-		atIndex := strings.Index(email, "@")
-		if plusIndex == -1 {
-			plusIndex = atIndex
-		}
-		email = strings.ReplaceAll(email[0:plusIndex], ".", "") + email[atIndex:]
-		if !m[email] {
-			m[email] = true
-			count++
-		}
-	}
-	return count
-}
diff --git a/problems/unique-email-addresses/unique_email_addresses_test.go b/problems/unique-email-addresses/unique_email_addresses_test.go
deleted file mode 100644
index f9f3af6f2..000000000
--- a/problems/unique-email-addresses/unique_email_addresses_test.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package problem929
-
-import "testing"
-
-type testType struct {
-	in   []string
-	want int
-}
-
-func TestNumUniqueEmails(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []string{"test.email+alex@leetcode.com", "test.e.mail+bob.cathy@leetcode.com", "testemail+david@lee.ttode.com"},
-			want: 2,
-		},
-		{
-			in:   []string{"awesee+wang@awesee.cn", "awesee.wang@awesee.cn", "aweSee+wang@awesee.cn"},
-			want: 3,
-		},
-	}
-
-	for _, tt := range tests {
-		got := numUniqueEmails(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/unique-length-3-palindromic-subsequences/README.md b/problems/unique-length-3-palindromic-subsequences/README.md
deleted file mode 100644
index 842141df7..000000000
--- a/problems/unique-length-3-palindromic-subsequences/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../concatenation-of-array "Concatenation of Array")
-　　　　　　　　　　　　　　　　
-[Next >](../painting-a-grid-with-three-different-colors "Painting a Grid With Three Different Colors")
-
-## [1930. Unique Length-3 Palindromic Subsequences (Medium)](https://leetcode.com/problems/unique-length-3-palindromic-subsequences "长度为 3 的不同回文子序列")
-
-<p>Given a string <code>s</code>, return <em>the number of <strong>unique palindromes of length three</strong> that are a <strong>subsequence</strong> of </em><code>s</code>.</p>
-
-<p>Note that even if there are multiple ways to obtain the same subsequence, it is still only counted <strong>once</strong>.</p>
-
-<p>A <strong>palindrome</strong> is a string that reads the same forwards and backwards.</p>
-
-<p>A <strong>subsequence</strong> of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.</p>
-
-<ul>
-	<li>For example, <code>&quot;ace&quot;</code> is a subsequence of <code>&quot;<u>a</u>b<u>c</u>d<u>e</u>&quot;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aabca&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> The 3 palindromic subsequences of length 3 are:
-- &quot;aba&quot; (subsequence of &quot;<u>a</u>a<u>b</u>c<u>a</u>&quot;)
-- &quot;aaa&quot; (subsequence of &quot;<u>aa</u>bc<u>a</u>&quot;)
-- &quot;aca&quot; (subsequence of &quot;<u>a</u>ab<u>ca</u>&quot;)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;adc&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no palindromic subsequences of length 3 in &quot;adc&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;bbcbaba&quot;
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> The 4 palindromic subsequences of length 3 are:
-- &quot;bbb&quot; (subsequence of &quot;<u>bb</u>c<u>b</u>aba&quot;)
-- &quot;bcb&quot; (subsequence of &quot;<u>b</u>b<u>cb</u>aba&quot;)
-- &quot;bab&quot; (subsequence of &quot;<u>b</u>bcb<u>ab</u>a&quot;)
-- &quot;aba&quot; (subsequence of &quot;bbcb<u>aba</u>&quot;)
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of only lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What is the maximum number of length-3 palindromic strings?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How can we keep track of the characters that appeared to the left of a given position?
-</details>
diff --git a/problems/unique-morse-code-words/README.md b/problems/unique-morse-code-words/README.md
deleted file mode 100644
index cc8a0767d..000000000
--- a/problems/unique-morse-code-words/README.md
+++ /dev/null
@@ -1,68 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../bricks-falling-when-hit "Bricks Falling When Hit")
-　　　　　　　　　　　　　　　　
-[Next >](../split-array-with-same-average "Split Array With Same Average")
-
-## [804. Unique Morse Code Words (Easy)](https://leetcode.com/problems/unique-morse-code-words "唯一摩尔斯密码词")
-
-<p>International Morse Code defines a standard encoding where each letter is mapped to a series of dots and dashes, as follows:</p>
-
-<ul>
-	<li><code>&#39;a&#39;</code> maps to <code>&quot;.-&quot;</code>,</li>
-	<li><code>&#39;b&#39;</code> maps to <code>&quot;-...&quot;</code>,</li>
-	<li><code>&#39;c&#39;</code> maps to <code>&quot;-.-.&quot;</code>, and so on.</li>
-</ul>
-
-<p>For convenience, the full table for the <code>26</code> letters of the English alphabet is given below:</p>
-
-<pre>
-[&quot;.-&quot;,&quot;-...&quot;,&quot;-.-.&quot;,&quot;-..&quot;,&quot;.&quot;,&quot;..-.&quot;,&quot;--.&quot;,&quot;....&quot;,&quot;..&quot;,&quot;.---&quot;,&quot;-.-&quot;,&quot;.-..&quot;,&quot;--&quot;,&quot;-.&quot;,&quot;---&quot;,&quot;.--.&quot;,&quot;--.-&quot;,&quot;.-.&quot;,&quot;...&quot;,&quot;-&quot;,&quot;..-&quot;,&quot;...-&quot;,&quot;.--&quot;,&quot;-..-&quot;,&quot;-.--&quot;,&quot;--..&quot;]</pre>
-
-<p>Given an array of strings <code>words</code> where each word can be written as a concatenation of the Morse code of each letter.</p>
-
-<ul>
-	<li>For example, <code>&quot;cab&quot;</code> can be written as <code>&quot;-.-..--...&quot;</code>, which is the concatenation of <code>&quot;-.-.&quot;</code>, <code>&quot;.-&quot;</code>, and <code>&quot;-...&quot;</code>. We will call such a concatenation the <strong>transformation</strong> of a word.</li>
-</ul>
-
-<p>Return <em>the number of different <strong>transformations</strong> among all words we have</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;gin&quot;,&quot;zen&quot;,&quot;gig&quot;,&quot;msg&quot;]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> The transformation of each word is:
-&quot;gin&quot; -&gt; &quot;--...-.&quot;
-&quot;zen&quot; -&gt; &quot;--...-.&quot;
-&quot;gig&quot; -&gt; &quot;--...--.&quot;
-&quot;msg&quot; -&gt; &quot;--...--.&quot;
-There are 2 different transformations: &quot;--...-.&quot; and &quot;--...--.&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;a&quot;]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 100</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 12</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/unique-morse-code-words/unique_morse_code_words.go b/problems/unique-morse-code-words/unique_morse_code_words.go
deleted file mode 100644
index 54fae0451..000000000
--- a/problems/unique-morse-code-words/unique_morse_code_words.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package problem804
-
-func uniqueMorseRepresentations(words []string) int {
-	list := [...]string{".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."}
-	m := make(map[string]bool)
-	for _, word := range words {
-		k := ""
-		for i := 0; i < len(word); i++ {
-			k += list[word[i]-'a']
-		}
-		m[k] = true
-	}
-	return len(m)
-}
diff --git a/problems/unique-morse-code-words/unique_morse_code_words_test.go b/problems/unique-morse-code-words/unique_morse_code_words_test.go
deleted file mode 100644
index 4abf94755..000000000
--- a/problems/unique-morse-code-words/unique_morse_code_words_test.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem804
-
-import "testing"
-
-type testType struct {
-	in   []string
-	want int
-}
-
-func TestUniqueMorseRepresentations(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []string{"gin", "zen", "gig", "msg"},
-			want: 2,
-		},
-		{
-			in:   []string{"hello", "word"},
-			want: 2,
-		},
-	}
-	for _, tt := range tests {
-		got := uniqueMorseRepresentations(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/unique-number-of-occurrences/README.md b/problems/unique-number-of-occurrences/README.md
deleted file mode 100644
index 9340795c8..000000000
--- a/problems/unique-number-of-occurrences/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-skiplist "Design Skiplist")
-　　　　　　　　　　　　　　　　
-[Next >](../get-equal-substrings-within-budget "Get Equal Substrings Within Budget")
-
-## [1207. Unique Number of Occurrences (Easy)](https://leetcode.com/problems/unique-number-of-occurrences "独一无二的出现次数")
-
-<p>Given an array of integers <code>arr</code>, return <code>true</code> if the number of occurrences of each value in the array is <strong>unique</strong>, or <code>false</code> otherwise.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2,2,1,1,3]
-<strong>Output:</strong> true
-<strong>Explanation:</strong>&nbsp;The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,2]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [-3,0,1,-3,1,1,1,-3,10,0]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length&nbsp;&lt;= 1000</code></li>
-	<li><code>-1000 &lt;= arr[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the number of occurrences of each element in the array using a hash map.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Iterate through the hash map and check if there is a repeated value.
-</details>
diff --git a/problems/unique-orders-and-customers-per-month/README.md b/problems/unique-orders-and-customers-per-month/README.md
deleted file mode 100644
index be33a1b8b..000000000
--- a/problems/unique-orders-and-customers-per-month/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../put-boxes-into-the-warehouse-i "Put Boxes Into the Warehouse I")
-　　　　　　　　　　　　　　　　
-[Next >](../detect-pattern-of-length-m-repeated-k-or-more-times "Detect Pattern of Length M Repeated K or More Times")
-
-## [1565. Unique Orders and Customers Per Month (Easy)](https://leetcode.com/problems/unique-orders-and-customers-per-month "按月统计订单数与顾客数")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/unique-orders-and-customers-per-month/mysql_schemas.sql b/problems/unique-orders-and-customers-per-month/mysql_schemas.sql
deleted file mode 100644
index 6f3b8f4d1..000000000
--- a/problems/unique-orders-and-customers-per-month/mysql_schemas.sql
+++ /dev/null
@@ -1,12 +0,0 @@
-Create table If Not Exists Orders (order_id int, order_date date, customer_id int, invoice int);
-Truncate table Orders;
-insert into Orders (order_id, order_date, customer_id, invoice) values ('1', '2020-09-15', '1', '30');
-insert into Orders (order_id, order_date, customer_id, invoice) values ('2', '2020-09-17', '2', '90');
-insert into Orders (order_id, order_date, customer_id, invoice) values ('3', '2020-10-06', '3', '20');
-insert into Orders (order_id, order_date, customer_id, invoice) values ('4', '2020-10-20', '3', '21');
-insert into Orders (order_id, order_date, customer_id, invoice) values ('5', '2020-11-10', '1', '10');
-insert into Orders (order_id, order_date, customer_id, invoice) values ('6', '2020-11-21', '2', '15');
-insert into Orders (order_id, order_date, customer_id, invoice) values ('7', '2020-12-01', '4', '55');
-insert into Orders (order_id, order_date, customer_id, invoice) values ('8', '2020-12-03', '4', '77');
-insert into Orders (order_id, order_date, customer_id, invoice) values ('9', '2021-01-07', '3', '31');
-insert into Orders (order_id, order_date, customer_id, invoice) values ('10', '2021-01-15', '2', '20');
diff --git a/problems/unique-paths-ii/README.md b/problems/unique-paths-ii/README.md
deleted file mode 100644
index 7ebd71fff..000000000
--- a/problems/unique-paths-ii/README.md
+++ /dev/null
@@ -1,92 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-paths "Unique Paths")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-path-sum "Minimum Path Sum")
-
-## [63. Unique Paths II (Medium)](https://leetcode.com/problems/unique-paths-ii "不同路径 II")
-
-<p>A robot is located at the top-left corner of a <code>m x n</code> grid (marked &#39;Start&#39; in the diagram below).</p>
-
-<p>The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked &#39;Finish&#39; in the diagram below).</p>
-
-<p>Now consider if some obstacles are added to the grids. How many unique paths would there be?</p>
-
-<p>An obstacle and space is marked as <code>1</code> and <code>0</code> respectively in the grid.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/04/robot1.jpg" style="width: 242px; height: 242px;" />
-<pre>
-<strong>Input:</strong> obstacleGrid = [[0,0,0],[0,1,0],[0,0,0]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There is one obstacle in the middle of the 3x3 grid above.
-There are two ways to reach the bottom-right corner:
-1. Right -&gt; Right -&gt; Down -&gt; Down
-2. Down -&gt; Down -&gt; Right -&gt; Right
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/04/robot2.jpg" style="width: 162px; height: 162px;" />
-<pre>
-<strong>Input:</strong> obstacleGrid = [[0,1],[0,0]]
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m ==&nbsp;obstacleGrid.length</code></li>
-	<li><code>n ==&nbsp;obstacleGrid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li><code>obstacleGrid[i][j]</code> is <code>0</code> or <code>1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Unique Paths](../unique-paths) (Medium)
-  1. [Unique Paths III](../unique-paths-iii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The robot can only move either down or right. Hence any cell in the first row can only be reached from the cell left to it. However, if any cell has an obstacle, you don't let that cell contribute to any path. So, for the first row, the number of ways will simply be 
-
-<pre>
-if obstacleGrid[i][j] is not an obstacle
-     obstacleGrid[i,j] = obstacleGrid[i,j - 1] 
-else
-     obstacleGrid[i,j] = 0
-</pre>
-
-You can do a similar processing for finding out the number of ways of reaching the cells in the first column.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-For any other cell, we can find out the number of ways of reaching it, by making use of the number of ways of reaching the cell directly above it and the cell to the left of it in the grid. This is because these are the only two directions from which the robot can come to the current cell.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Since we are making use of pre-computed values along the iteration, this becomes a dynamic programming problem.
-
-<pre>
-if obstacleGrid[i][j] is not an obstacle
-     obstacleGrid[i,j] = obstacleGrid[i,j - 1]  + obstacleGrid[i - 1][j]
-else
-     obstacleGrid[i,j] = 0
-</pre>
-
-</pre>
-</details>
diff --git a/problems/unique-paths-ii/unique_paths_ii.go b/problems/unique-paths-ii/unique_paths_ii.go
deleted file mode 100644
index 239af0f38..000000000
--- a/problems/unique-paths-ii/unique_paths_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem63
diff --git a/problems/unique-paths-ii/unique_paths_ii_test.go b/problems/unique-paths-ii/unique_paths_ii_test.go
deleted file mode 100644
index 239af0f38..000000000
--- a/problems/unique-paths-ii/unique_paths_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem63
diff --git a/problems/unique-paths-iii/README.md b/problems/unique-paths-iii/README.md
deleted file mode 100644
index 23d0cdfc2..000000000
--- a/problems/unique-paths-iii/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distribute-coins-in-binary-tree "Distribute Coins in Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../time-based-key-value-store "Time Based Key-Value Store")
-
-## [980. Unique Paths III (Hard)](https://leetcode.com/problems/unique-paths-iii "不同路径 III")
-
-<p>You are given an <code>m x n</code> integer array <code>grid</code> where <code>grid[i][j]</code> could be:</p>
-
-<ul>
-	<li><code>1</code> representing the starting square. There is exactly one starting square.</li>
-	<li><code>2</code> representing the ending square. There is exactly one ending square.</li>
-	<li><code>0</code> representing empty squares we can walk over.</li>
-	<li><code>-1</code> representing obstacles that we cannot walk over.</li>
-</ul>
-
-<p>Return <em>the number of 4-directional walks from the starting square to the ending square, that walk over every non-obstacle square exactly once</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/02/lc-unique1.jpg" style="width: 324px; height: 245px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,0,0,0],[0,0,0,0],[0,0,2,-1]]
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> We have the following two paths: 
-1. (0,0),(0,1),(0,2),(0,3),(1,3),(1,2),(1,1),(1,0),(2,0),(2,1),(2,2)
-2. (0,0),(1,0),(2,0),(2,1),(1,1),(0,1),(0,2),(0,3),(1,3),(1,2),(2,2)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/02/lc-unique2.jpg" style="width: 324px; height: 245px;" />
-<pre>
-<strong>Input:</strong> grid = [[1,0,0,0],[0,0,0,0],[0,0,0,2]]
-<strong>Output:</strong> 4
-<strong>Explanation:</strong> We have the following four paths: 
-1. (0,0),(0,1),(0,2),(0,3),(1,3),(1,2),(1,1),(1,0),(2,0),(2,1),(2,2),(2,3)
-2. (0,0),(0,1),(1,1),(1,0),(2,0),(2,1),(2,2),(1,2),(0,2),(0,3),(1,3),(2,3)
-3. (0,0),(1,0),(2,0),(2,1),(2,2),(1,2),(1,1),(0,1),(0,2),(0,3),(1,3),(2,3)
-4. (0,0),(1,0),(2,0),(2,1),(1,1),(0,1),(0,2),(0,3),(1,3),(1,2),(2,2),(2,3)
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/08/02/lc-unique3-.jpg" style="width: 164px; height: 165px;" />
-<pre>
-<strong>Input:</strong> grid = [[0,1],[2,0]]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no path that walks over every empty square exactly once.
-Note that the starting and ending square can be anywhere in the grid.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 20</code></li>
-	<li><code>1 &lt;= m * n &lt;= 20</code></li>
-	<li><code>-1 &lt;= grid[i][j] &lt;= 2</code></li>
-	<li>There is exactly one starting cell and one ending cell.</li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Sudoku Solver](../sudoku-solver) (Hard)
-  1. [Unique Paths II](../unique-paths-ii) (Medium)
-  1. [Word Search II](../word-search-ii) (Hard)
diff --git a/problems/unique-paths-iii/unique_paths_iii.go b/problems/unique-paths-iii/unique_paths_iii.go
deleted file mode 100644
index 288241d48..000000000
--- a/problems/unique-paths-iii/unique_paths_iii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem980
diff --git a/problems/unique-paths/README.md b/problems/unique-paths/README.md
deleted file mode 100644
index 8aaef9e07..000000000
--- a/problems/unique-paths/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../rotate-list "Rotate List")
-　　　　　　　　　　　　　　　　
-[Next >](../unique-paths-ii "Unique Paths II")
-
-## [62. Unique Paths (Medium)](https://leetcode.com/problems/unique-paths "不同路径")
-
-<p>A robot is located at the top-left corner of a <code>m x n</code> grid (marked &#39;Start&#39; in the diagram below).</p>
-
-<p>The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked &#39;Finish&#39; in the diagram below).</p>
-
-<p>How many possible unique paths are there?</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://assets.leetcode.com/uploads/2018/10/22/robot_maze.png" style="width: 400px; height: 183px;" />
-<pre>
-<strong>Input:</strong> m = 3, n = 7
-<strong>Output:</strong> 28
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> m = 3, n = 2
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>
-From the top-left corner, there are a total of 3 ways to reach the bottom-right corner:
-1. Right -&gt; Down -&gt; Down
-2. Down -&gt; Down -&gt; Right
-3. Down -&gt; Right -&gt; Down
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> m = 7, n = 3
-<strong>Output:</strong> 28
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> m = 3, n = 3
-<strong>Output:</strong> 6
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li>It&#39;s guaranteed that the answer will be less than or equal to <code>2 * 10<sup>9</sup></code>.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-
-### Similar Questions
-  1. [Unique Paths II](../unique-paths-ii) (Medium)
-  1. [Minimum Path Sum](../minimum-path-sum) (Medium)
-  1. [Dungeon Game](../dungeon-game) (Hard)
diff --git a/problems/unique-paths/unique_paths.go b/problems/unique-paths/unique_paths.go
deleted file mode 100644
index 5a2f3d26f..000000000
--- a/problems/unique-paths/unique_paths.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem62
diff --git a/problems/unique-paths/unique_paths_test.go b/problems/unique-paths/unique_paths_test.go
deleted file mode 100644
index 5a2f3d26f..000000000
--- a/problems/unique-paths/unique_paths_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem62
diff --git a/problems/unique-substrings-in-wraparound-string/README.md b/problems/unique-substrings-in-wraparound-string/README.md
deleted file mode 100644
index e9ff09c60..000000000
--- a/problems/unique-substrings-in-wraparound-string/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-the-repetitions "Count The Repetitions")
-　　　　　　　　　　　　　　　　
-[Next >](../validate-ip-address "Validate IP Address")
-
-## [467. Unique Substrings in Wraparound String (Medium)](https://leetcode.com/problems/unique-substrings-in-wraparound-string "环绕字符串中唯一的子字符串")
-
-<p>We define the string <code>s</code> to be the infinite wraparound string of <code>&quot;abcdefghijklmnopqrstuvwxyz&quot;</code>, so <code>s</code> will look like this:</p>
-
-<ul>
-	<li><code>&quot;...zabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcd....&quot;</code>.</li>
-</ul>
-
-<p>Given a string <code>p</code>, return <em>the number of <strong>unique non-empty substrings</strong> of </em><code>p</code><em> are present in </em><code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> p = &quot;a&quot;
-<strong>Output:</strong> 1
-Explanation: Only the substring &quot;a&quot; of p is in s.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> p = &quot;cac&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> There are two substrings (&quot;a&quot;, &quot;c&quot;) of p in s.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> p = &quot;zab&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> There are six substrings (&quot;z&quot;, &quot;a&quot;, &quot;b&quot;, &quot;za&quot;, &quot;ab&quot;, and &quot;zab&quot;) of p in s.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= p.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>p</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-One possible solution might be to consider allocating an array size of 26 for each character in the alphabet. (Credits to @r2ysxu)
-</details>
diff --git a/problems/unique-substrings-in-wraparound-string/unique_substrings_in_wraparound_string.go b/problems/unique-substrings-in-wraparound-string/unique_substrings_in_wraparound_string.go
deleted file mode 100644
index 2a4720da2..000000000
--- a/problems/unique-substrings-in-wraparound-string/unique_substrings_in_wraparound_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem467
diff --git a/problems/unique-substrings-in-wraparound-string/unique_substrings_in_wraparound_string_test.go b/problems/unique-substrings-in-wraparound-string/unique_substrings_in_wraparound_string_test.go
deleted file mode 100644
index 2a4720da2..000000000
--- a/problems/unique-substrings-in-wraparound-string/unique_substrings_in_wraparound_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem467
diff --git a/problems/unique-substrings-with-equal-digit-frequency/README.md b/problems/unique-substrings-with-equal-digit-frequency/README.md
deleted file mode 100644
index 18b80c84a..000000000
--- a/problems/unique-substrings-with-equal-digit-frequency/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-time-to-remove-all-cars-containing-illegal-goods "Minimum Time to Remove All Cars Containing Illegal Goods")
-　　　　　　　　　　　　　　　　
-[Next >](../count-operations-to-obtain-zero "Count Operations to Obtain Zero")
-
-## [2168. Unique Substrings With Equal Digit Frequency (Medium)](https://leetcode.com/problems/unique-substrings-with-equal-digit-frequency "")
-
-
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Hash Function](../../tag/hash-function/README.md)]
-  [[Rolling Hash](../../tag/rolling-hash/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-With the constraints, could we try every substring?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Yes, checking every substring has runtime O(n^2), which will pass.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-How can we make sure we only count unique substrings?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use a set to store previously counted substrings. Hashing a string s of length m takes O(m) time. Is there a fast way to compute the hash of s if we know the hash of s[0..m - 2]?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-Use a rolling hash.
-</details>
diff --git a/problems/unique-word-abbreviation/README.md b/problems/unique-word-abbreviation/README.md
deleted file mode 100644
index 882609e43..000000000
--- a/problems/unique-word-abbreviation/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-the-duplicate-number "Find the Duplicate Number")
-　　　　　　　　　　　　　　　　
-[Next >](../game-of-life "Game of Life")
-
-## [288. Unique Word Abbreviation (Medium)](https://leetcode.com/problems/unique-word-abbreviation "单词的唯一缩写")
-
-<p>An abbreviation of a word follows the form &lt;first letter&gt;&lt;number&gt;&lt;last letter&gt;. Below are some examples of word abbreviations:</p>
-
-<pre>
-a) it                      --&gt; it    (no abbreviation)
-
-     1
-     &darr;
-b) d|o|g                   --&gt; d1g
-
-              1    1  1
-     1---5----0----5--8
-     &darr;   &darr;    &darr;    &darr;  &darr;    
-c) i|nternationalizatio|n  --&gt; i18n
-
-              1
-     1---5----0
-&nbsp;    &darr;   &darr;    &darr;
-d) l|ocalizatio|n          --&gt; l10n
-</pre>
-
-<p>Assume you have a dictionary and given a word, find whether its abbreviation is unique in the dictionary. A word&#39;s abbreviation is unique if no <i>other</i> word from the dictionary has the same abbreviation.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-Given dictionary = [ &quot;deer&quot;, &quot;door&quot;, &quot;cake&quot;, &quot;card&quot; ]
-
-isUnique(&quot;dear&quot;) -&gt; <code>false</code>
-isUnique(&quot;cart&quot;) -&gt; <code>true</code>
-isUnique(&quot;cane&quot;) -&gt; <code>false</code>
-isUnique(&quot;make&quot;) -&gt; <code>true</code>
-</pre>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Two Sum III - Data structure design](../two-sum-iii-data-structure-design) (Easy)
-  1. [Generalized Abbreviation](../generalized-abbreviation) (Medium)
diff --git a/problems/unique-word-abbreviation/unique_word_abbreviation.go b/problems/unique-word-abbreviation/unique_word_abbreviation.go
deleted file mode 100644
index dd66be77a..000000000
--- a/problems/unique-word-abbreviation/unique_word_abbreviation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem288
diff --git a/problems/unique-word-abbreviation/unique_word_abbreviation_test.go b/problems/unique-word-abbreviation/unique_word_abbreviation_test.go
deleted file mode 100644
index dd66be77a..000000000
--- a/problems/unique-word-abbreviation/unique_word_abbreviation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem288
diff --git a/problems/univalued-binary-tree/README.md b/problems/univalued-binary-tree/README.md
deleted file mode 100644
index 2c9f33f16..000000000
--- a/problems/univalued-binary-tree/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../least-operators-to-express-number "Least Operators to Express Number")
-　　　　　　　　　　　　　　　　
-[Next >](../vowel-spellchecker "Vowel Spellchecker")
-
-## [965. Univalued Binary Tree (Easy)](https://leetcode.com/problems/univalued-binary-tree "单值二叉树")
-
-<p>A binary tree is <strong>uni-valued</strong> if every node in the tree has the same value.</p>
-
-<p>Given the <code>root</code> of a binary tree, return <code>true</code><em> if the given tree is <strong>uni-valued</strong>, or </em><code>false</code><em> otherwise.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/28/unival_bst_1.png" style="width: 265px; height: 172px;" />
-<pre>
-<strong>Input:</strong> root = [1,1,1,1,1,null,1]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2018/12/28/unival_bst_2.png" style="width: 198px; height: 169px;" />
-<pre>
-<strong>Input:</strong> root = [2,2,2,5,2]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 100]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt; 100</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Find All The Lonely Nodes](../find-all-the-lonely-nodes) (Easy)
diff --git a/problems/univalued-binary-tree/univalued_binary_tree.go b/problems/univalued-binary-tree/univalued_binary_tree.go
deleted file mode 100644
index 9a1d09899..000000000
--- a/problems/univalued-binary-tree/univalued_binary_tree.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package problem965
-
-import "github.com/awesee/leetcode/internal/kit"
-
-// TreeNode - Definition for a binary tree node.
-type TreeNode = kit.TreeNode
-
-/**
- * Definition for a binary tree node.
- * type TreeNode struct {
- *     Val int
- *     Left *TreeNode
- *     Right *TreeNode
- * }
- */
-func isUnivalTree(root *TreeNode) bool {
-	if root == nil {
-		return true
-	}
-	if root.Left != nil && root.Left.Val != root.Val {
-		return false
-	}
-	if root.Right != nil && root.Right.Val != root.Val {
-		return false
-	}
-	return isUnivalTree(root.Left) && isUnivalTree(root.Right)
-}
diff --git a/problems/univalued-binary-tree/univalued_binary_tree_test.go b/problems/univalued-binary-tree/univalued_binary_tree_test.go
deleted file mode 100644
index 77d80c2e6..000000000
--- a/problems/univalued-binary-tree/univalued_binary_tree_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem965
-
-import (
-	"testing"
-
-	"github.com/awesee/leetcode/internal/kit"
-)
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestIsUnivalTree(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 1, 1, 1, 1, kit.NULL, 1},
-			want: true,
-		},
-		{
-			in:   []int{2, 2, 2, 5, 2},
-			want: false,
-		},
-		{
-			in:   []int{3, 3, 3, 3, 5},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isUnivalTree(kit.SliceInt2TreeNode(tt.in))
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/unpopular-books/README.md b/problems/unpopular-books/README.md
deleted file mode 100644
index 3eae0fff4..000000000
--- a/problems/unpopular-books/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../game-play-analysis-v "Game Play Analysis V")
-　　　　　　　　　　　　　　　　
-[Next >](../two-sum-less-than-k "Two Sum Less Than K")
-
-## [1098. Unpopular Books (Medium)](https://leetcode.com/problems/unpopular-books "小众书籍")
-
-<p>Table:&nbsp;<code>Books</code></p>
-
-<pre>
-+----------------+---------+
-| Column Name    | Type    |
-+----------------+---------+
-| book_id        | int     |
-| name           | varchar |
-| available_from | date    |
-+----------------+---------+
-book_id is the primary key of this table.
-</pre>
-
-<p>Table:&nbsp;<code>Orders</code></p>
-
-<pre>
-+----------------+---------+
-| Column Name    | Type    |
-+----------------+---------+
-| order_id       | int     |
-| book_id        | int     |
-| quantity       | int     |
-| dispatch_date  | date    |
-+----------------+---------+
-order_id is the primary key of this table.
-book_id is a foreign key to the Books table.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query that reports the&nbsp;<strong>books</strong> that have sold <strong>less than 10</strong> copies in the last year, excluding books that have been available for less than 1 month from today. <strong>Assume today is 2019-06-23</strong>.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Books table:
-+---------+--------------------+----------------+
-| book_id | name               | available_from |
-+---------+--------------------+----------------+
-| 1       | &quot;Kalila And Demna&quot; | 2010-01-01     |
-| 2       | &quot;28 Letters&quot;       | 2012-05-12     |
-| 3       | &quot;The Hobbit&quot;       | 2019-06-10     |
-| 4       | &quot;13 Reasons Why&quot;   | 2019-06-01     |
-| 5       | &quot;The Hunger Games&quot; | 2008-09-21     |
-+---------+--------------------+----------------+
-
-Orders table:
-+----------+---------+----------+---------------+
-| order_id | book_id | quantity | dispatch_date |
-+----------+---------+----------+---------------+
-| 1        | 1       | 2        | 2018-07-26    |
-| 2        | 1       | 1        | 2018-11-05    |
-| 3        | 3       | 8        | 2019-06-11    |
-| 4        | 4       | 6        | 2019-06-05    |
-| 5        | 4       | 5        | 2019-06-20    |
-| 6        | 5       | 9        | 2009-02-02    |
-| 7        | 5       | 8        | 2010-04-13    |
-+----------+---------+----------+---------------+
-
-Result table:
-+-----------+--------------------+
-| book_id   | name               |
-+-----------+--------------------+
-| 1         | &quot;Kalila And Demna&quot; |
-| 2         | &quot;28 Letters&quot;       |
-| 5         | &quot;The Hunger Games&quot; |
-+-----------+--------------------+
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/unpopular-books/mysql_schemas.sql b/problems/unpopular-books/mysql_schemas.sql
deleted file mode 100644
index 171c4e090..000000000
--- a/problems/unpopular-books/mysql_schemas.sql
+++ /dev/null
@@ -1,16 +0,0 @@
-Create table If Not Exists Books (book_id int, name varchar(50), available_from date);
-Create table If Not Exists Orders (order_id int, book_id int, quantity int, dispatch_date date);
-Truncate table Books;
-insert into Books (book_id, name, available_from) values ('1', 'Kalila And Demna', '2010-01-01');
-insert into Books (book_id, name, available_from) values ('2', '28 Letters', '2012-05-12');
-insert into Books (book_id, name, available_from) values ('3', 'The Hobbit', '2019-06-10');
-insert into Books (book_id, name, available_from) values ('4', '13 Reasons Why', '2019-06-01');
-insert into Books (book_id, name, available_from) values ('5', 'The Hunger Games', '2008-09-21');
-Truncate table Orders;
-insert into Orders (order_id, book_id, quantity, dispatch_date) values ('1', '1', '2', '2018-07-26');
-insert into Orders (order_id, book_id, quantity, dispatch_date) values ('2', '1', '1', '2018-11-05');
-insert into Orders (order_id, book_id, quantity, dispatch_date) values ('3', '3', '8', '2019-06-11');
-insert into Orders (order_id, book_id, quantity, dispatch_date) values ('4', '4', '6', '2019-06-05');
-insert into Orders (order_id, book_id, quantity, dispatch_date) values ('5', '4', '5', '2019-06-20');
-insert into Orders (order_id, book_id, quantity, dispatch_date) values ('6', '5', '9', '2009-02-02');
-insert into Orders (order_id, book_id, quantity, dispatch_date) values ('7', '5', '8', '2010-04-13');
diff --git a/problems/unpopular-books/unpopular_books.sql b/problems/unpopular-books/unpopular_books.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/unpopular-books/unpopular_books.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/user-activity-for-the-past-30-days-i/README.md b/problems/user-activity-for-the-past-30-days-i/README.md
deleted file mode 100644
index 123c6b996..000000000
--- a/problems/user-activity-for-the-past-30-days-i/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stone-game-ii "Stone Game II")
-　　　　　　　　　　　　　　　　
-[Next >](../user-activity-for-the-past-30-days-ii "User Activity for the Past 30 Days II")
-
-## [1141. User Activity for the Past 30 Days I (Easy)](https://leetcode.com/problems/user-activity-for-the-past-30-days-i "查询近30天活跃用户数")
-
-<p>Table: <code>Activity</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| user_id       | int     |
-| session_id    | int     |
-| activity_date | date    |
-| activity_type | enum    |
-+---------------+---------+
-There is no primary key for this table, it may have duplicate rows.
-The activity_type column is an ENUM of type (&#39;open_session&#39;, &#39;end_session&#39;, &#39;scroll_down&#39;, &#39;send_message&#39;).
-The table shows the user activities for a social media website. 
-Note that each session belongs to exactly one user.
-</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find the daily active user count for a period of 30 days ending <strong>2019-07-27</strong>&nbsp;inclusively. A user was active on some day if he/she made at least one activity on that day.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Activity table:
-+---------+------------+---------------+---------------+
-| user_id | session_id | activity_date | activity_type |
-+---------+------------+---------------+---------------+
-| 1       | 1          | 2019-07-20    | open_session  |
-| 1       | 1          | 2019-07-20    | scroll_down   |
-| 1       | 1          | 2019-07-20    | end_session   |
-| 2       | 4          | 2019-07-20    | open_session  |
-| 2       | 4          | 2019-07-21    | send_message  |
-| 2       | 4          | 2019-07-21    | end_session   |
-| 3       | 2          | 2019-07-21    | open_session  |
-| 3       | 2          | 2019-07-21    | send_message  |
-| 3       | 2          | 2019-07-21    | end_session   |
-| 4       | 3          | 2019-06-25    | open_session  |
-| 4       | 3          | 2019-06-25    | end_session   |
-+---------+------------+---------------+---------------+
-
-Result table:
-+------------+--------------+ 
-| day        | active_users |
-+------------+--------------+ 
-| 2019-07-20 | 2            |
-| 2019-07-21 | 2            |
-+------------+--------------+ 
-Note that we do not care about days with zero active users.
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/user-activity-for-the-past-30-days-i/mysql_schemas.sql b/problems/user-activity-for-the-past-30-days-i/mysql_schemas.sql
deleted file mode 100644
index 82d002fab..000000000
--- a/problems/user-activity-for-the-past-30-days-i/mysql_schemas.sql
+++ /dev/null
@@ -1,13 +0,0 @@
-Create table If Not Exists Activity (user_id int, session_id int, activity_date date, activity_type ENUM('open_session', 'end_session', 'scroll_down', 'send_message'));
-Truncate table Activity;
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('1', '1', '2019-07-20', 'open_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('1', '1', '2019-07-20', 'scroll_down');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('1', '1', '2019-07-20', 'end_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('2', '4', '2019-07-20', 'open_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('2', '4', '2019-07-21', 'send_message');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('2', '4', '2019-07-21', 'end_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('3', '2', '2019-07-21', 'open_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('3', '2', '2019-07-21', 'send_message');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('3', '2', '2019-07-21', 'end_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('4', '3', '2019-06-25', 'open_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('4', '3', '2019-06-25', 'end_session');
diff --git a/problems/user-activity-for-the-past-30-days-ii/README.md b/problems/user-activity-for-the-past-30-days-ii/README.md
deleted file mode 100644
index 798f30669..000000000
--- a/problems/user-activity-for-the-past-30-days-ii/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../user-activity-for-the-past-30-days-i "User Activity for the Past 30 Days I")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-common-subsequence "Longest Common Subsequence")
-
-## [1142. User Activity for the Past 30 Days II (Easy)](https://leetcode.com/problems/user-activity-for-the-past-30-days-ii "过去30天的用户活动 II")
-
-<p>Table: <code>Activity</code></p>
-
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| user_id       | int     |
-| session_id    | int     |
-| activity_date | date    |
-| activity_type | enum    |
-+---------------+---------+
-There is no primary key for this table, it may have duplicate rows.
-The activity_type column is an ENUM of type (&#39;open_session&#39;, &#39;end_session&#39;, &#39;scroll_down&#39;, &#39;send_message&#39;).
-The table shows the user activities for a social media website.
-Note that each session belongs to exactly one user.</pre>
-
-<p>&nbsp;</p>
-
-<p>Write an SQL query to find the average number of sessions per user for a period of 30 days ending <strong>2019-07-27</strong>&nbsp;inclusively, <strong>rounded to 2 decimal places</strong>. The sessions we want to count for a user are those with at least one activity in that time period.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-Activity table:
-+---------+------------+---------------+---------------+
-| user_id | session_id | activity_date | activity_type |
-+---------+------------+---------------+---------------+
-| 1       | 1          | 2019-07-20    | open_session  |
-| 1       | 1          | 2019-07-20    | scroll_down   |
-| 1       | 1          | 2019-07-20    | end_session   |
-| 2       | 4          | 2019-07-20    | open_session  |
-| 2       | 4          | 2019-07-21    | send_message  |
-| 2       | 4          | 2019-07-21    | end_session   |
-| 3       | 2          | 2019-07-21    | open_session  |
-| 3       | 2          | 2019-07-21    | send_message  |
-| 3       | 2          | 2019-07-21    | end_session   |
-| 3       | 5          | 2019-07-21    | open_session  |
-| 3       | 5          | 2019-07-21    | scroll_down   |
-| 3       | 5          | 2019-07-21    | end_session   |
-| 4       | 3          | 2019-06-25    | open_session  |
-| 4       | 3          | 2019-06-25    | end_session   |
-+---------+------------+---------------+---------------+
-
-Result table:
-+---------------------------+ 
-| average_sessions_per_user |
-+---------------------------+ 
-| 1.33                      |
-+---------------------------+ 
-User 1 and 2 each had 1 session in the past 30 days while user 3 had 2 sessions so the average is (1 + 1 + 2) / 3 = 1.33.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/user-activity-for-the-past-30-days-ii/mysql_schemas.sql b/problems/user-activity-for-the-past-30-days-ii/mysql_schemas.sql
deleted file mode 100644
index fa331255b..000000000
--- a/problems/user-activity-for-the-past-30-days-ii/mysql_schemas.sql
+++ /dev/null
@@ -1,16 +0,0 @@
-Create table If Not Exists Activity (user_id int, session_id int, activity_date date, activity_type ENUM('open_session', 'end_session', 'scroll_down', 'send_message'));
-Truncate table Activity;
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('1', '1', '2019-07-20', 'open_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('1', '1', '2019-07-20', 'scroll_down');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('1', '1', '2019-07-20', 'end_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('2', '4', '2019-07-20', 'open_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('2', '4', '2019-07-21', 'send_message');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('2', '4', '2019-07-21', 'end_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('3', '2', '2019-07-21', 'open_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('3', '2', '2019-07-21', 'send_message');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('3', '2', '2019-07-21', 'end_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('3', '5', '2019-07-21', 'open_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('3', '5', '2019-07-21', 'scroll_down');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('3', '5', '2019-07-21', 'end_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('4', '3', '2019-06-25', 'open_session');
-insert into Activity (user_id, session_id, activity_date, activity_type) values ('4', '3', '2019-06-25', 'end_session');
diff --git a/problems/user-purchase-platform/README.md b/problems/user-purchase-platform/README.md
deleted file mode 100644
index 6fce28e7c..000000000
--- a/problems/user-purchase-platform/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../active-businesses "Active Businesses")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-equivalent-domino-pairs "Number of Equivalent Domino Pairs")
-
-## [1127. User Purchase Platform (Hard)](https://leetcode.com/problems/user-purchase-platform "用户购买平台")
-
-<p>Table: <code>Spending</code></p>
-
-<pre>
-+-------------+---------+
-| Column Name | Type    |
-+-------------+---------+
-| user_id     | int     |
-| spend_date  | date    |
-| platform    | enum    | 
-| amount      | int     |
-+-------------+---------+
-The table logs the spendings history of users that make purchases from an online shopping website which has a desktop and a mobile application.
-(user_id, spend_date, platform) is the primary key of this table.
-The platform column is an ENUM type of (&#39;desktop&#39;, &#39;mobile&#39;).
-</pre>
-
-<p>Write an SQL query to find the total number of users and the total amount spent&nbsp;using mobile <strong>only</strong>, desktop <strong>only</strong> and <strong>both</strong> mobile and desktop together for each date.</p>
-
-<p>The query result format is in the following example:</p>
-
-<pre>
-<code>Spending</code> table:
-+---------+------------+----------+--------+
-| user_id | spend_date | platform | amount |
-+---------+------------+----------+--------+
-| 1       | 2019-07-01 | mobile   | 100    |
-| 1       | 2019-07-01 | desktop  | 100    |
-| 2       | 2019-07-01 | mobile   | 100    |
-| 2       | 2019-07-02 | mobile   | 100    |
-| 3       | 2019-07-01 | desktop  | 100    |
-| 3       | 2019-07-02 | desktop  | 100    |
-+---------+------------+----------+--------+
-
-Result table:
-+------------+----------+--------------+-------------+
-| spend_date | platform | total_amount | total_users |
-+------------+----------+--------------+-------------+
-| 2019-07-01 | desktop  | 100          | 1           |
-| 2019-07-01 | mobile   | 100          | 1           |
-| 2019-07-01 | both     | 200          | 1           |
-| 2019-07-02 | desktop  | 100          | 1           |
-| 2019-07-02 | mobile   | 100          | 1           |
-| 2019-07-02 | both     | 0            | 0           |
-+------------+----------+--------------+-------------+ 
-On 2019-07-01, user 1 purchased using <strong>both</strong> desktop and mobile, user 2 purchased using mobile <strong>only</strong> and user 3 purchased using desktop <strong>only</strong>.
-On 2019-07-02, user 2 purchased using mobile <strong>only</strong>, user 3 purchased using desktop <strong>only</strong> and no one purchased using <strong>both</strong> platforms.</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/user-purchase-platform/mysql_schemas.sql b/problems/user-purchase-platform/mysql_schemas.sql
deleted file mode 100644
index a971b1127..000000000
--- a/problems/user-purchase-platform/mysql_schemas.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-Create table If Not Exists Spending (user_id int, spend_date date, platform ENUM('desktop', 'mobile'), amount int);
-Truncate table Spending;
-insert into Spending (user_id, spend_date, platform, amount) values ('1', '2019-07-01', 'mobile', '100');
-insert into Spending (user_id, spend_date, platform, amount) values ('1', '2019-07-01', 'desktop', '100');
-insert into Spending (user_id, spend_date, platform, amount) values ('2', '2019-07-01', 'mobile', '100');
-insert into Spending (user_id, spend_date, platform, amount) values ('2', '2019-07-02', 'mobile', '100');
-insert into Spending (user_id, spend_date, platform, amount) values ('3', '2019-07-01', 'desktop', '100');
-insert into Spending (user_id, spend_date, platform, amount) values ('3', '2019-07-02', 'desktop', '100');
diff --git a/problems/user-purchase-platform/user_purchase_platform.sql b/problems/user-purchase-platform/user_purchase_platform.sql
deleted file mode 100644
index bae62cf19..000000000
--- a/problems/user-purchase-platform/user_purchase_platform.sql
+++ /dev/null
@@ -1 +0,0 @@
-# Write your MySQL query statement below
diff --git a/problems/users-that-actively-request-confirmation-messages/README.md b/problems/users-that-actively-request-confirmation-messages/README.md
deleted file mode 100644
index d8642a55d..000000000
--- a/problems/users-that-actively-request-confirmation-messages/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-genetic-difference-query "Maximum Genetic Difference Query")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-common-subsequence-between-sorted-arrays "Longest Common Subsequence Between Sorted Arrays")
-
-## [1939. Users That Actively Request Confirmation Messages (Easy)](https://leetcode.com/problems/users-that-actively-request-confirmation-messages "主动请求确认消息的用户")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/users-that-actively-request-confirmation-messages/mysql_schemas.sql b/problems/users-that-actively-request-confirmation-messages/mysql_schemas.sql
deleted file mode 100644
index 53a892c9b..000000000
--- a/problems/users-that-actively-request-confirmation-messages/mysql_schemas.sql
+++ /dev/null
@@ -1,16 +0,0 @@
-Create table If Not Exists Signups (user_id int, time_stamp datetime);
-Create table If Not Exists Confirmations (user_id int, time_stamp datetime, action ENUM('confirmed','timeout'));
-Truncate table Signups;
-insert into Signups (user_id, time_stamp) values ('3', '2020-03-21 10:16:13');
-insert into Signups (user_id, time_stamp) values ('7', '2020-01-04 13:57:59');
-insert into Signups (user_id, time_stamp) values ('2', '2020-07-29 23:09:44');
-insert into Signups (user_id, time_stamp) values ('6', '2020-12-09 10:39:37');
-Truncate table Confirmations;
-insert into Confirmations (user_id, time_stamp, action) values ('3', '2021-01-06 03:30:46', 'timeout');
-insert into Confirmations (user_id, time_stamp, action) values ('3', '2021-01-06 03:37:45', 'timeout');
-insert into Confirmations (user_id, time_stamp, action) values ('7', '2021-06-12 11:57:29', 'confirmed');
-insert into Confirmations (user_id, time_stamp, action) values ('7', '2021-06-13 11:57:30', 'confirmed');
-insert into Confirmations (user_id, time_stamp, action) values ('2', '2021-01-22 00:00:00', 'confirmed');
-insert into Confirmations (user_id, time_stamp, action) values ('2', '2021-01-23 00:00:00', 'timeout');
-insert into Confirmations (user_id, time_stamp, action) values ('6', '2021-10-23 14:14:14', 'confirmed');
-insert into Confirmations (user_id, time_stamp, action) values ('6', '2021-10-24 14:14:13', 'timeout');
diff --git a/problems/utf-8-validation/README.md b/problems/utf-8-validation/README.md
deleted file mode 100644
index fa8e947a3..000000000
--- a/problems/utf-8-validation/README.md
+++ /dev/null
@@ -1,119 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../is-subsequence "Is Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../decode-string "Decode String")
-
-## [393. UTF-8 Validation (Medium)](https://leetcode.com/problems/utf-8-validation "UTF-8 编码验证")
-
-<p>Given an integer array <code>data</code> representing the data, return whether it is a valid <strong>UTF-8</strong> encoding.</p>
-
-<p>A character in <strong>UTF8</strong> can be from <b>1 to 4 bytes</b> long, subjected to the following rules:</p>
-
-<ol>
-	<li>For a <strong>1-byte</strong> character, the first bit is a <code>0</code>, followed by its Unicode code.</li>
-	<li>For an <strong>n-bytes</strong> character, the first <code>n</code> bits are all one&#39;s, the <code>n + 1</code> bit is <code>0</code>, followed by <code>n - 1</code> bytes with the most significant <code>2</code> bits being <code>10</code>.</li>
-</ol>
-
-<p>This is how the UTF-8 encoding would work:</p>
-
-<pre>
-<code>   Char. number range  |        UTF-8 octet sequence
-      (hexadecimal)    |              (binary)
-   --------------------+---------------------------------------------
-   0000 0000-0000 007F | 0xxxxxxx
-   0000 0080-0000 07FF | 110xxxxx 10xxxxxx
-   0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
-   0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx</code>
-</pre>
-
-<p><b>Note: </b>The input is an array of integers. Only the <b>least significant 8 bits</b> of each integer is used to store the data. This means each integer represents only 1 byte of data.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> data = [197,130,1]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> data represents the octet sequence: 11000101 10000010 00000001.
-It is a valid utf-8 encoding for a 2-bytes character followed by a 1-byte character.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> data = [235,140,4]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> data represented the octet sequence: 11101011 10001100 00000100.
-The first 3 bits are all one&#39;s and the 4th bit is 0 means it is a 3-bytes character.
-The next byte is a continuation byte which starts with 10 and that&#39;s correct.
-But the second continuation byte does not start with 10, so it is invalid.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= data.length &lt;= 2 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= data[i] &lt;= 255</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-All you have to do is follow the rules. For a given integer, obtain its binary representation in the string form and work with the rules given in the problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-An integer can either represent the start of a UTF-8 character, or a part of an existing UTF-8 character. There are two separate rules for these two scenarios in the problem.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-If an integer is a part of an existing UTF-8 character, simply check the 2 most significant bits of in the binary representation string. They should be <b>10</b>. If the integer represents the start of a UTF-8 character, then the first few bits would be <b>1</b> followed by a <b>0</b>. The number of initial bits (most significant) bits determines the length of the UTF-8 character. 
-
-<br><br>
-<b>Note:</b> The array can contain multiple valid UTF-8 characters.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-String manipulation will work fine here. But, it is too slow. Can we instead use <b>bit manipulation</b> to do the validations instead of string manipulations?
-</details>
-
-<details>
-<summary>Hint 5</summary>
-We can use bit masking to check how many initial bits are set for a given number. <b>We only need to work with the 8 least significant bits as mentioned in the problem.</b>
-
-<pre>
-mask = 1 << 7
-while mask & num:
-    n_bytes += 1
-    mask = mask >> 1
-</pre>
-
-Can you use bit-masking to perform the second validation as well i.e. checking if the most significant bit is 1 and the second most significant bit a 0?
-</details>
-
-<details>
-<summary>Hint 6</summary>
-To check if the most significant bit is a 1 and the second most significant bit is a 0, we can make use of the following two masks.
-
-<pre>
-mask1 = 1 << 7
-mask2 = 1 << 6
-
-if not (num & mask1 and not (num & mask2)):
-    return False
-</pre>
-</details>
diff --git a/problems/utf-8-validation/utf_8_validation.go b/problems/utf-8-validation/utf_8_validation.go
deleted file mode 100644
index b1a1db819..000000000
--- a/problems/utf-8-validation/utf_8_validation.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem393
-
-func validUtf8(data []int) bool {
-	u := 0
-	for _, v := range data {
-		if u == 0 && v>>7 == 0 { // 0b0
-			u = 0
-		} else if u == 0 && v>>5 == 6 { // 0b110
-			u = 1
-		} else if u == 0 && v>>4 == 14 { // 0b1110
-			u = 2
-		} else if u == 0 && v>>3 == 30 { // 0b11110
-			u = 3
-		} else if u > 0 && v>>6 == 2 { // 0b10
-			u--
-		} else {
-			return false
-		}
-	}
-	return u == 0
-}
diff --git a/problems/utf-8-validation/utf_8_validation_test.go b/problems/utf-8-validation/utf_8_validation_test.go
deleted file mode 100644
index 4588c16d3..000000000
--- a/problems/utf-8-validation/utf_8_validation_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem393
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestValidUtf8(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{197},
-			want: false,
-		},
-		{
-			in:   []int{197, 130, 1},
-			want: true,
-		},
-		{
-			in:   []int{235, 140, 4},
-			want: false,
-		},
-		{
-			in:   []int{248},
-			want: false,
-		},
-		{
-			in:   []int{194, 155, 231, 184, 185, 246, 176, 131, 161, 222, 174, 227, 162, 134, 241, 154, 168, 185, 218, 178, 229, 187, 139, 246, 178, 187, 139, 204, 146, 225, 148, 179, 245, 139, 172, 134, 193, 156, 233, 131, 154, 240, 166, 188, 190, 216, 150, 230, 145, 144, 240, 167, 140, 163, 221, 190, 238, 168, 139, 241, 154, 159, 164, 199, 170, 224, 173, 140, 244, 182, 143, 134, 206, 181, 227, 172, 141, 241, 146, 159, 170, 202, 134, 230, 142, 163, 244, 172, 140, 191},
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := validUtf8(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/valid-anagram/README.md b/problems/valid-anagram/README.md
deleted file mode 100644
index 782c3336d..000000000
--- a/problems/valid-anagram/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../different-ways-to-add-parentheses "Different Ways to Add Parentheses")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-word-distance "Shortest Word Distance")
-
-## [242. Valid Anagram (Easy)](https://leetcode.com/problems/valid-anagram "有效的字母异位词")
-
-<p>Given two strings <code>s</code> and <code>t</code>, return <code>true</code> <em>if</em> <code>t</code> <em>is an anagram of</em> <code>s</code><em>, and</em> <code>false</code> <em>otherwise</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "anagram", t = "nagaram"
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "rat", t = "car"
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length, t.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>s</code> and <code>t</code> consist of lowercase English letters.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> What if the inputs contain Unicode characters? How would you adapt your solution to such a case?</p>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Group Anagrams](../group-anagrams) (Medium)
-  1. [Palindrome Permutation](../palindrome-permutation) (Easy)
-  1. [Find All Anagrams in a String](../find-all-anagrams-in-a-string) (Medium)
diff --git a/problems/valid-anagram/valid_anagram.go b/problems/valid-anagram/valid_anagram.go
deleted file mode 100644
index b4178b134..000000000
--- a/problems/valid-anagram/valid_anagram.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem242
-
-func isAnagram(s string, t string) bool {
-	sl := len(s)
-	tl := len(t)
-	if sl != tl {
-		return false
-	}
-	var sc [256]int
-	for i := 0; i < sl; i++ {
-		sc[s[i]]++
-	}
-	for i := 0; i < tl; i++ {
-		sc[t[i]]--
-		if sc[t[i]] < 0 {
-			return false
-		}
-	}
-	return true
-}
diff --git a/problems/valid-anagram/valid_anagram_test.go b/problems/valid-anagram/valid_anagram_test.go
deleted file mode 100644
index 10899056d..000000000
--- a/problems/valid-anagram/valid_anagram_test.go
+++ /dev/null
@@ -1,46 +0,0 @@
-package problem242
-
-import "testing"
-
-type testType struct {
-	s    string
-	t    string
-	want bool
-}
-
-func TestIsAnagram(t *testing.T) {
-	tests := [...]testType{
-		{
-			s:    "anagram",
-			t:    "nagaram",
-			want: true,
-		},
-		{
-			s:    "hannah",
-			t:    "hanna",
-			want: false,
-		},
-		{
-			s:    "this is string",
-			t:    "this is string long",
-			want: false,
-		},
-		{
-			s:    "this is string",
-			t:    "this as string",
-			want: false,
-		},
-		{
-			s:    "你好，世界",
-			t:    "世界，你好",
-			want: true,
-		},
-	}
-
-	for _, tt := range tests {
-		got := isAnagram(tt.s, tt.t)
-		if got != tt.want {
-			t.Fatalf("in: %v %v, got: %v, want: %v", tt.s, tt.t, got, tt.want)
-		}
-	}
-}
diff --git a/problems/valid-arrangement-of-pairs/README.md b/problems/valid-arrangement-of-pairs/README.md
deleted file mode 100644
index 68c06e545..000000000
--- a/problems/valid-arrangement-of-pairs/README.md
+++ /dev/null
@@ -1,87 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../step-by-step-directions-from-a-binary-tree-node-to-another "Step-By-Step Directions From a Binary Tree Node to Another")
-　　　　　　　　　　　　　　　　
-[Next >](../subsequence-of-size-k-with-the-largest-even-sum "Subsequence of Size K With the Largest Even Sum")
-
-## [2097. Valid Arrangement of Pairs (Hard)](https://leetcode.com/problems/valid-arrangement-of-pairs "合法重新排列数对")
-
-<p>You are given a <strong>0-indexed</strong> 2D integer array <code>pairs</code> where <code>pairs[i] = [start<sub>i</sub>, end<sub>i</sub>]</code>. An arrangement of <code>pairs</code> is <strong>valid</strong> if for every index <code>i</code> where <code>1 &lt;= i &lt; pairs.length</code>, we have <code>end<sub>i-1</sub> == start<sub>i</sub></code>.</p>
-
-<p>Return <em><strong>any</strong> valid arrangement of </em><code>pairs</code>.</p>
-
-<p><strong>Note:</strong> The inputs will be generated such that there exists a valid arrangement of <code>pairs</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> pairs = [[5,1],[4,5],[11,9],[9,4]]
-<strong>Output:</strong> [[11,9],[9,4],[4,5],[5,1]]
-<strong>Explanation:
-</strong>This is a valid arrangement since end<sub>i-1</sub> always equals start<sub>i</sub>.
-end<sub>0</sub> = 9 == 9 = start<sub>1</sub> 
-end<sub>1</sub> = 4 == 4 = start<sub>2</sub>
-end<sub>2</sub> = 5 == 5 = start<sub>3</sub>
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> pairs = [[1,3],[3,2],[2,1]]
-<strong>Output:</strong> [[1,3],[3,2],[2,1]]
-<strong>Explanation:</strong>
-This is a valid arrangement since end<sub>i-1</sub> always equals start<sub>i</sub>.
-end<sub>0</sub> = 3 == 3 = start<sub>1</sub>
-end<sub>1</sub> = 2 == 2 = start<sub>2</sub>
-The arrangements [[2,1],[1,3],[3,2]] and [[3,2],[2,1],[1,3]] are also valid.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> pairs = [[1,2],[1,3],[2,1]]
-<strong>Output:</strong> [[1,2],[2,1],[1,3]]
-<strong>Explanation:</strong>
-This is a valid arrangement since end<sub>i-1</sub> always equals start<sub>i</sub>.
-end<sub>0</sub> = 2 == 2 = start<sub>1</sub>
-end<sub>1</sub> = 1 == 1 = start<sub>2</sub>
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= pairs.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>pairs[i].length == 2</code></li>
-	<li><code>0 &lt;= start<sub>i</sub>, end<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
-	<li><code>start<sub>i</sub> != end<sub>i</sub></code></li>
-	<li>No two pairs are exactly the same.</li>
-	<li>There <strong>exists</strong> a valid arrangement of <code>pairs</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Eulerian Circuit](../../tag/eulerian-circuit/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Could you convert this into a graph problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Consider the pairs as edges and each number as a node.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-We have to find an Eulerian path of this graph. Hierholzer’s algorithm can be used.
-</details>
diff --git a/problems/valid-boomerang/README.md b/problems/valid-boomerang/README.md
deleted file mode 100644
index 5cd0d3c99..000000000
--- a/problems/valid-boomerang/README.md
+++ /dev/null
@@ -1,43 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../escape-a-large-maze "Escape a Large Maze")
-　　　　　　　　　　　　　　　　
-[Next >](../binary-search-tree-to-greater-sum-tree "Binary Search Tree to Greater Sum Tree")
-
-## [1037. Valid Boomerang (Easy)](https://leetcode.com/problems/valid-boomerang "有效的回旋镖")
-
-<p>Given an array <code>points</code> where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> represents a point on the <strong>X-Y</strong> plane, return <code>true</code> <em>if these points are a <strong>boomerang</strong></em>.</p>
-
-<p>A <strong>boomerang</strong> is a set of three points that are <strong>all distinct</strong> and <strong>not in a straight line</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> points = [[1,1],[2,3],[3,2]]
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> points = [[1,1],[2,2],[3,3]]
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>points.length == 3</code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Math](../../tag/math/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-3 points form a boomerang if and only if the triangle formed from them has non-zero area.
-</details>
diff --git a/problems/valid-boomerang/valid_boomerang.go b/problems/valid-boomerang/valid_boomerang.go
deleted file mode 100644
index 857370327..000000000
--- a/problems/valid-boomerang/valid_boomerang.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package problem1037
-
-func isBoomerang(points [][]int) bool {
-	ans := points[0][0] * (points[1][1] - points[2][1])
-	ans += points[1][0] * (points[2][1] - points[0][1])
-	ans += points[2][0] * (points[0][1] - points[1][1])
-	return ans != 0
-}
diff --git a/problems/valid-boomerang/valid_boomerang_test.go b/problems/valid-boomerang/valid_boomerang_test.go
deleted file mode 100644
index b9cc50f73..000000000
--- a/problems/valid-boomerang/valid_boomerang_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem1037
-
-import "testing"
-
-type testType struct {
-	in   [][]int
-	want bool
-}
-
-func TestIsBoomerang(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]int{
-				{1, 1},
-				{2, 3},
-				{3, 2},
-			},
-			want: true,
-		},
-		{
-			in: [][]int{
-				{1, 1},
-				{2, 2},
-				{3, 3},
-			},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isBoomerang(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/valid-mountain-array/README.md b/problems/valid-mountain-array/README.md
deleted file mode 100644
index ce394ccd2..000000000
--- a/problems/valid-mountain-array/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../distinct-subsequences-ii "Distinct Subsequences II")
-　　　　　　　　　　　　　　　　
-[Next >](../di-string-match "DI String Match")
-
-## [941. Valid Mountain Array (Easy)](https://leetcode.com/problems/valid-mountain-array "有效的山脉数组")
-
-<p>Given an array of integers <code>arr</code>, return <em><code>true</code> if and only if it is a valid mountain array</em>.</p>
-
-<p>Recall that arr is a mountain array if and only if:</p>
-
-<ul>
-	<li><code>arr.length &gt;= 3</code></li>
-	<li>There exists some <code>i</code> with <code>0 &lt; i &lt; arr.length - 1</code> such that:
-	<ul>
-		<li><code>arr[0] &lt; arr[1] &lt; ... &lt; arr[i - 1] &lt; arr[i] </code></li>
-		<li><code>arr[i] &gt; arr[i + 1] &gt; ... &gt; arr[arr.length - 1]</code></li>
-	</ul>
-	</li>
-</ul>
-<img src="https://assets.leetcode.com/uploads/2019/10/20/hint_valid_mountain_array.png" width="500" />
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> arr = [2,1]
-<strong>Output:</strong> false
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> arr = [3,5,5]
-<strong>Output:</strong> false
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> arr = [0,3,2,1]
-<strong>Output:</strong> true
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= arr[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-It's very easy to keep track of a monotonically increasing or decreasing ordering of elements. You just need to be able to determine the start of the valley in the mountain and from that point onwards, it should be a valley i.e. no mini-hills after that. Use this information in regards to the values in the array and you will be able to come up with a straightforward solution.
-</details>
diff --git a/problems/valid-mountain-array/valid_mountain_array.go b/problems/valid-mountain-array/valid_mountain_array.go
deleted file mode 100644
index 3c9f1d7db..000000000
--- a/problems/valid-mountain-array/valid_mountain_array.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem941
-
-func validMountainArray(A []int) bool {
-	flag := false
-	if len(A) < 3 {
-		return false
-	}
-	for i, v := range A[1:] {
-		if !flag && v <= A[i] {
-			if flag = true; i == 0 {
-				return false
-			}
-		}
-		if flag && v >= A[i] {
-			return false
-		}
-	}
-	return flag
-}
diff --git a/problems/valid-mountain-array/valid_mountain_array_test.go b/problems/valid-mountain-array/valid_mountain_array_test.go
deleted file mode 100644
index e0d0f2ab6..000000000
--- a/problems/valid-mountain-array/valid_mountain_array_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package problem941
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestValidMountainArray(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{2, 1},
-			want: false,
-		},
-		{
-			in:   []int{3, 5, 5},
-			want: false,
-		},
-		{
-			in:   []int{0, 3, 2, 1},
-			want: true,
-		},
-		{
-			in:   []int{1, 2, 3, 2},
-			want: true,
-		},
-		{
-			in:   []int{9, 8, 7, 6, 5, 4, 3, 2, 1, 0},
-			want: false,
-		},
-		{
-			in:   []int{1, 2, 3, 4, 5},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := validMountainArray(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/valid-number/README.md b/problems/valid-number/README.md
deleted file mode 100644
index 8b6567a68..000000000
--- a/problems/valid-number/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-path-sum "Minimum Path Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../plus-one "Plus One")
-
-## [65. Valid Number (Hard)](https://leetcode.com/problems/valid-number "有效数字")
-
-<p>A <strong>valid number</strong> can be split up into these components (in order):</p>
-
-<ol>
-	<li>A <strong>decimal number</strong> or an <strong>integer</strong>.</li>
-	<li>(Optional) An <code>&#39;e&#39;</code> or <code>&#39;E&#39;</code>, followed by an <strong>integer</strong>.</li>
-</ol>
-
-<p>A <strong>decimal number</strong> can be split up into these components (in order):</p>
-
-<ol>
-	<li>(Optional) A sign character (either <code>&#39;+&#39;</code> or <code>&#39;-&#39;</code>).</li>
-	<li>One of the following formats:
-	<ol>
-		<li>One or more digits, followed by a dot <code>&#39;.&#39;</code>.</li>
-		<li>One or more digits, followed by a dot <code>&#39;.&#39;</code>, followed by one or more digits.</li>
-		<li>A dot <code>&#39;.&#39;</code>, followed by one or more digits.</li>
-	</ol>
-	</li>
-</ol>
-
-<p>An <strong>integer</strong> can be split up into these components (in order):</p>
-
-<ol>
-	<li>(Optional) A sign character (either <code>&#39;+&#39;</code> or <code>&#39;-&#39;</code>).</li>
-	<li>One or more digits.</li>
-</ol>
-
-<p>For example, all the following are valid numbers: <code>[&quot;2&quot;, &quot;0089&quot;, &quot;-0.1&quot;, &quot;+3.14&quot;, &quot;4.&quot;, &quot;-.9&quot;, &quot;2e10&quot;, &quot;-90E3&quot;, &quot;3e+7&quot;, &quot;+6e-1&quot;, &quot;53.5e93&quot;, &quot;-123.456e789&quot;]</code>, while the following are not valid numbers: <code>[&quot;abc&quot;, &quot;1a&quot;, &quot;1e&quot;, &quot;e3&quot;, &quot;99e2.5&quot;, &quot;--6&quot;, &quot;-+3&quot;, &quot;95a54e53&quot;]</code>.</p>
-
-<p>Given a string <code>s</code>, return <code>true</code><em> if </em><code>s</code><em> is a <strong>valid number</strong></em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;0&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;e&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;.&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;.1&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 20</code></li>
-	<li><code>s</code> consists of only English letters (both uppercase and lowercase), digits (<code>0-9</code>), plus <code>&#39;+&#39;</code>, minus <code>&#39;-&#39;</code>, or dot <code>&#39;.&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [String to Integer (atoi)](../string-to-integer-atoi) (Medium)
diff --git a/problems/valid-number/valid_number.go b/problems/valid-number/valid_number.go
deleted file mode 100644
index 8d23f91d2..000000000
--- a/problems/valid-number/valid_number.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package problem65
-
-import (
-	"strconv"
-	"strings"
-)
-
-func isNumber(s string) bool {
-	s = strings.TrimSpace(s)
-	_, err := strconv.ParseFloat(s, 64)
-	return err == nil || err.(*strconv.NumError).Err != strconv.ErrSyntax
-}
diff --git a/problems/valid-number/valid_number_test.go b/problems/valid-number/valid_number_test.go
deleted file mode 100644
index ed8d47f62..000000000
--- a/problems/valid-number/valid_number_test.go
+++ /dev/null
@@ -1,79 +0,0 @@
-package problem65
-
-import "testing"
-
-type testType struct {
-	in   string
-	want bool
-}
-
-func TestIsNumber(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "0",
-			want: true,
-		},
-		{
-			in:   " 0.1",
-			want: true,
-		},
-		{
-			in:   "abc",
-			want: false,
-		},
-		{
-			in:   "1 a",
-			want: false,
-		},
-		{
-			in:   "2e10",
-			want: true,
-		},
-		{
-			in:   " -90e3   ",
-			want: true,
-		},
-		{
-			in:   " 1e",
-			want: false,
-		},
-		{
-			in:   "e3",
-			want: false,
-		},
-		{
-			in:   " 6e-1",
-			want: true,
-		},
-		{
-			in:   " 99e2.5 ",
-			want: false,
-		},
-		{
-			in:   "53.5e93",
-			want: true,
-		},
-		{
-			in:   " --6 ",
-			want: false,
-		},
-		{
-			in:   "-+3",
-			want: false,
-		},
-		{
-			in:   "95a54e53",
-			want: false,
-		},
-		{
-			in:   "078332e437",
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := isNumber(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/valid-palindrome-ii/README.md b/problems/valid-palindrome-ii/README.md
deleted file mode 100644
index 192d58d64..000000000
--- a/problems/valid-palindrome-ii/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../24-game "24 Game")
-　　　　　　　　　　　　　　　　
-[Next >](../next-closest-time "Next Closest Time")
-
-## [680. Valid Palindrome II (Easy)](https://leetcode.com/problems/valid-palindrome-ii "验证回文字符串 Ⅱ")
-
-<p>Given a string <code>s</code>, return <code>true</code> <em>if the </em><code>s</code><em> can be palindrome after deleting <strong>at most one</strong> character from it</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aba&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abca&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> You could delete the character &#39;c&#39;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abc&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Valid Palindrome](../valid-palindrome) (Easy)
diff --git a/problems/valid-palindrome-ii/valid_palindrome_ii.go b/problems/valid-palindrome-ii/valid_palindrome_ii.go
deleted file mode 100644
index 8f94b9f6c..000000000
--- a/problems/valid-palindrome-ii/valid_palindrome_ii.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem680
-
-func validPalindrome(s string) bool {
-	start, end := 0, len(s)-1
-	i, j, times := 0, 0, 0
-	for start < end {
-		if s[start] == s[end] {
-			start++
-			end--
-		} else {
-			times++
-			if times == 1 {
-				i, j = start, end
-				start++
-			} else if times == 2 {
-				start, end = i, j-1
-			} else {
-				return false
-			}
-		}
-	}
-	return true
-}
diff --git a/problems/valid-palindrome-ii/valid_palindrome_ii_test.go b/problems/valid-palindrome-ii/valid_palindrome_ii_test.go
deleted file mode 100644
index 0191af625..000000000
--- a/problems/valid-palindrome-ii/valid_palindrome_ii_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem680
-
-import "testing"
-
-type testType struct {
-	in   string
-	want bool
-}
-
-func TestValidPalindrome(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "aba",
-			want: true,
-		},
-		{
-			in:   "abca",
-			want: true,
-		},
-		{
-			in:   "hello",
-			want: false,
-		},
-		{
-			in:   "abcdcbda",
-			want: true,
-		},
-		{
-			in:   "abcbabbbca",
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := validPalindrome(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/valid-palindrome-iii/README.md b/problems/valid-palindrome-iii/README.md
deleted file mode 100644
index b9c826790..000000000
--- a/problems/valid-palindrome-iii/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../stepping-numbers "Stepping Numbers")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-cost-to-move-chips-to-the-same-position "Minimum Cost to Move Chips to The Same Position")
-
-## [1216. Valid Palindrome III (Hard)](https://leetcode.com/problems/valid-palindrome-iii "验证回文字符串 III")
-
-<p>Given a string <code>s</code>&nbsp;and an integer&nbsp;<code>k</code>, find out if the given string is&nbsp;a&nbsp;<em>K-Palindrome</em> or not.</p>
-
-<p>A string is K-Palindrome if it can be&nbsp;transformed&nbsp;into a palindrome by removing at most <code>k</code> characters from it.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;abcdeca&quot;, k = 2
-<strong>Output:</strong> true
-<strong>Explanation: </strong>Remove &#39;b&#39; and &#39;e&#39; characters.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code>&nbsp;has only lowercase English letters.</li>
-	<li><code>1 &lt;= k&nbsp;&lt;= s.length</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Can you reduce this problem to a classic problem?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-The problem is equivalent to finding any palindromic subsequence of length at least N-K where N is the length of the string.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Try to find the longest palindromic subsequence.
-</details>
-
-<details>
-<summary>Hint 4</summary>
-Use DP to do that.
-</details>
diff --git a/problems/valid-palindrome/README.md b/problems/valid-palindrome/README.md
deleted file mode 100644
index c4df1f022..000000000
--- a/problems/valid-palindrome/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../binary-tree-maximum-path-sum "Binary Tree Maximum Path Sum")
-　　　　　　　　　　　　　　　　
-[Next >](../word-ladder-ii "Word Ladder II")
-
-## [125. Valid Palindrome (Easy)](https://leetcode.com/problems/valid-palindrome "验证回文串")
-
-<p>Given a string <code>s</code>, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;A man, a plan, a canal: Panama&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> &quot;amanaplanacanalpanama&quot; is a palindrome.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;race a car&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> &quot;raceacar&quot; is not a palindrome.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 2 * 10<sup>5</sup></code></li>
-	<li><code>s</code> consists only of printable ASCII characters.</li>
-</ul>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Palindrome Linked List](../palindrome-linked-list) (Easy)
-  1. [Valid Palindrome II](../valid-palindrome-ii) (Easy)
diff --git a/problems/valid-palindrome/valid_palindrome.go b/problems/valid-palindrome/valid_palindrome.go
deleted file mode 100644
index 48bfe3fd8..000000000
--- a/problems/valid-palindrome/valid_palindrome.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package problem125
-
-func isPalindrome(s string) bool {
-	start, end := 0, len(s)-1
-	for start < end {
-		if !isAlphanumeric(s[start]) {
-			start++
-			continue
-		}
-		if !isAlphanumeric(s[end]) {
-			end--
-			continue
-		}
-		x := s[start]
-		if s[start] >= 'a' {
-			x = s[start] + 'A' - 'a'
-		}
-		y := s[end]
-		if s[end] >= 'a' {
-			y = s[end] + 'A' - 'a'
-		}
-		if x != y {
-			return false
-		}
-		start++
-		end--
-	}
-	return true
-}
-
-func isAlphanumeric(b byte) bool {
-	return ('0' <= b && b <= '9') || ('A' <= b && b <= 'Z') || ('a' <= b && b <= 'z')
-}
diff --git a/problems/valid-palindrome/valid_palindrome_test.go b/problems/valid-palindrome/valid_palindrome_test.go
deleted file mode 100644
index ce2d6f7f9..000000000
--- a/problems/valid-palindrome/valid_palindrome_test.go
+++ /dev/null
@@ -1,44 +0,0 @@
-package problem125
-
-import "testing"
-
-type testType struct {
-	in   string
-	want bool
-}
-
-func TestIsPalindrome(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "A man, a plan, a canal: Panama",
-			want: true,
-		},
-		{
-			in:   "",
-			want: true,
-		},
-		{
-			in:   ".",
-			want: true,
-		},
-		{
-			in:   "12321",
-			want: true,
-		},
-		{
-			in:   "race a car",
-			want: false,
-		},
-		{
-			in:   "hello, world",
-			want: false,
-		},
-	}
-
-	for _, tt := range tests {
-		got := isPalindrome(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/valid-parentheses/README.md b/problems/valid-parentheses/README.md
deleted file mode 100644
index b71415bce..000000000
--- a/problems/valid-parentheses/README.md
+++ /dev/null
@@ -1,115 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../remove-nth-node-from-end-of-list "Remove Nth Node From End of List")
-　　　　　　　　　　　　　　　　
-[Next >](../merge-two-sorted-lists "Merge Two Sorted Lists")
-
-## [20. Valid Parentheses (Easy)](https://leetcode.com/problems/valid-parentheses "有效的括号")
-
-<p>Given a string <code>s</code> containing just the characters <code>&#39;(&#39;</code>, <code>&#39;)&#39;</code>, <code>&#39;{&#39;</code>, <code>&#39;}&#39;</code>, <code>&#39;[&#39;</code> and <code>&#39;]&#39;</code>, determine if the input string is valid.</p>
-
-<p>An input string is valid if:</p>
-
-<ol>
-	<li>Open brackets must be closed by the same type of brackets.</li>
-	<li>Open brackets must be closed in the correct order.</li>
-</ol>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;()&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;()[]{}&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;(]&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;([)]&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;{[]}&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>s</code> consists of parentheses only <code>&#39;()[]{}&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Generate Parentheses](../generate-parentheses) (Medium)
-  1. [Longest Valid Parentheses](../longest-valid-parentheses) (Hard)
-  1. [Remove Invalid Parentheses](../remove-invalid-parentheses) (Hard)
-  1. [Check If Word Is Valid After Substitutions](../check-if-word-is-valid-after-substitutions) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-An interesting property about a valid parenthesis expression is that a sub-expression of a valid expression should also be a valid expression. (Not every sub-expression) e.g.
-
-<pre>
-{ { } [ ] [ [ [ ] ] ] } is VALID expression
-          [ [ [ ] ] ]    is VALID sub-expression
-  { } [ ]                is VALID sub-expression
-</pre>
-
-Can we exploit this recursive structure somehow?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-What if whenever we encounter a matching pair of parenthesis in the expression, we simply remove it from the expression? This would keep on shortening the expression. e.g.
-
-<pre>
-{ { ( { } ) } }
-      |_|
-
-{ { (      ) } }
-    |______|
-
-{ {          } }
-  |__________|
-
-{                }
-|________________|
-
-VALID EXPRESSION!
-</pre>
-</details>
-
-<details>
-<summary>Hint 3</summary>
-The <b>stack</b> data structure can come in handy here in representing this recursive structure of the problem. We can't really process this from the inside out because we don't have an idea about the overall structure. But, the stack can help us process this recursively i.e. from outside to inwards.
-</details>
diff --git a/problems/valid-parentheses/valid_parentheses.go b/problems/valid-parentheses/valid_parentheses.go
deleted file mode 100644
index e78e8d809..000000000
--- a/problems/valid-parentheses/valid_parentheses.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package problem20
-
-func isValid(s string) bool {
-	m := map[byte]byte{
-		'(': ')',
-		'[': ']',
-		'{': '}',
-	}
-	l := len(s)
-	stack := make([]byte, l)
-	top := 0
-	for i := 0; i < l; i++ {
-		switch s[i] {
-		case '(', '[', '{':
-			stack[top] = m[s[i]]
-			top++
-		case ')', ']', '}':
-			if top > 0 && stack[top-1] == s[i] {
-				top--
-			} else {
-				return false
-			}
-		}
-	}
-	return top == 0
-}
diff --git a/problems/valid-parentheses/valid_parentheses_test.go b/problems/valid-parentheses/valid_parentheses_test.go
deleted file mode 100644
index 655d91820..000000000
--- a/problems/valid-parentheses/valid_parentheses_test.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package problem20
-
-import "testing"
-
-func TestIsValid(t *testing.T) {
-	tests := map[string]bool{
-		"":       true,
-		"()":     true,
-		"()[]{}": true,
-		"{[]}":   true,
-		"(]":     false,
-		"([)]":   false,
-		"([{)]":  false,
-		"([})]":  false,
-	}
-
-	for in, want := range tests {
-		got := isValid(in)
-		if got != want {
-			t.Fatalf("in: %v, got: %v, want: %v", in, got, want)
-		}
-	}
-}
-
-func BenchmarkIsValid(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		isValid("{[({[({[()]})]})]}")
-	}
-}
diff --git a/problems/valid-parenthesis-string/README.md b/problems/valid-parenthesis-string/README.md
deleted file mode 100644
index 3edabff41..000000000
--- a/problems/valid-parenthesis-string/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../map-sum-pairs "Map Sum Pairs")
-　　　　　　　　　　　　　　　　
-[Next >](../24-game "24 Game")
-
-## [678. Valid Parenthesis String (Medium)](https://leetcode.com/problems/valid-parenthesis-string "有效的括号字符串")
-
-<p>Given a string <code>s</code> containing only three types of characters: <code>&#39;(&#39;</code>, <code>&#39;)&#39;</code> and <code>&#39;*&#39;</code>, return <code>true</code> <em>if</em> <code>s</code> <em>is <strong>valid</strong></em>.</p>
-
-<p>The following rules define a <strong>valid</strong> string:</p>
-
-<ul>
-	<li>Any left parenthesis <code>&#39;(&#39;</code> must have a corresponding right parenthesis <code>&#39;)&#39;</code>.</li>
-	<li>Any right parenthesis <code>&#39;)&#39;</code> must have a corresponding left parenthesis <code>&#39;(&#39;</code>.</li>
-	<li>Left parenthesis <code>&#39;(&#39;</code> must go before the corresponding right parenthesis <code>&#39;)&#39;</code>.</li>
-	<li><code>&#39;*&#39;</code> could be treated as a single right parenthesis <code>&#39;)&#39;</code> or a single left parenthesis <code>&#39;(&#39;</code> or an empty string <code>&quot;&quot;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> s = "()"
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> s = "(*)"
-<strong>Output:</strong> true
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> s = "(*))"
-<strong>Output:</strong> true
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 100</code></li>
-	<li><code>s[i]</code> is <code>&#39;(&#39;</code>, <code>&#39;)&#39;</code> or <code>&#39;*&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Stack](../../tag/stack/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Special Binary String](../special-binary-string) (Hard)
-  1. [Check if a Parentheses String Can Be Valid](../check-if-a-parentheses-string-can-be-valid) (Medium)
diff --git a/problems/valid-parenthesis-string/valid_parenthesis_string.go b/problems/valid-parenthesis-string/valid_parenthesis_string.go
deleted file mode 100644
index 35e922a09..000000000
--- a/problems/valid-parenthesis-string/valid_parenthesis_string.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem678
diff --git a/problems/valid-parenthesis-string/valid_parenthesis_string_test.go b/problems/valid-parenthesis-string/valid_parenthesis_string_test.go
deleted file mode 100644
index 35e922a09..000000000
--- a/problems/valid-parenthesis-string/valid_parenthesis_string_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem678
diff --git a/problems/valid-perfect-square/README.md b/problems/valid-perfect-square/README.md
deleted file mode 100644
index cc1cf1509..000000000
--- a/problems/valid-perfect-square/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-leaves-of-binary-tree "Find Leaves of Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../largest-divisible-subset "Largest Divisible Subset")
-
-## [367. Valid Perfect Square (Easy)](https://leetcode.com/problems/valid-perfect-square "有效的完全平方数")
-
-<p>Given a <strong>positive</strong> integer <i>num</i>, write a function which returns True if <i>num</i> is a perfect square else False.</p>
-
-<p><b>Follow up:</b> <b>Do not</b> use any built-in library function such as <code>sqrt</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> num = 16
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> num = 14
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= num &lt;= 2^31 - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-
-### Similar Questions
-  1. [Sqrt(x)](../sqrtx) (Easy)
-  1. [Sum of Square Numbers](../sum-of-square-numbers) (Medium)
diff --git a/problems/valid-perfect-square/valid_perfect_square.go b/problems/valid-perfect-square/valid_perfect_square.go
deleted file mode 100644
index 7bb0af941..000000000
--- a/problems/valid-perfect-square/valid_perfect_square.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package problem367
-
-func isPerfectSquare(num int) bool {
-	for i := 1; num > 0; i += 2 {
-		num -= i
-	}
-	return num == 0
-}
diff --git a/problems/valid-perfect-square/valid_perfect_square_test.go b/problems/valid-perfect-square/valid_perfect_square_test.go
deleted file mode 100644
index 258f035eb..000000000
--- a/problems/valid-perfect-square/valid_perfect_square_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem367
-
-import "testing"
-
-type testType struct {
-	in   int
-	want bool
-}
-
-func TestIsPerfectSquare(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   16,
-			want: true,
-		},
-		{
-			in:   14,
-			want: false,
-		},
-		{
-			in:   0,
-			want: true,
-		},
-		{
-			in:   1,
-			want: true,
-		},
-		{
-			in:   3,
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		got := isPerfectSquare(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/valid-permutations-for-di-sequence/README.md b/problems/valid-permutations-for-di-sequence/README.md
deleted file mode 100644
index 6fe45763b..000000000
--- a/problems/valid-permutations-for-di-sequence/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../numbers-at-most-n-given-digit-set "Numbers At Most N Given Digit Set")
-　　　　　　　　　　　　　　　　
-[Next >](../fruit-into-baskets "Fruit Into Baskets")
-
-## [903. Valid Permutations for DI Sequence (Hard)](https://leetcode.com/problems/valid-permutations-for-di-sequence "DI 序列的有效排列")
-
-<p>You are given a string <code>s</code> of length <code>n</code> where <code>s[i]</code> is either:</p>
-
-<ul>
-	<li><code>&#39;D&#39;</code> means decreasing, or</li>
-	<li><code>&#39;I&#39;</code> means increasing.</li>
-</ul>
-
-<p>A permutation <code>perm</code> of <code>n + 1</code> integers of all the integers in the range <code>[0, n]</code> is called a <strong>valid permutation</strong> if for all valid <code>i</code>:</p>
-
-<ul>
-	<li>If <code>s[i] == &#39;D&#39;</code>, then <code>perm[i] &gt; perm[i + 1]</code>, and</li>
-	<li>If <code>s[i] == &#39;I&#39;</code>, then <code>perm[i] &lt; perm[i + 1]</code>.</li>
-</ul>
-
-<p>Return <em>the number of <strong>valid permutations</strong> </em><code>perm</code>. Since the answer may be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;DID&quot;
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> The 5 valid permutations of (0, 1, 2, 3) are:
-(1, 0, 3, 2)
-(2, 0, 3, 1)
-(2, 1, 3, 0)
-(3, 0, 2, 1)
-(3, 1, 2, 0)
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;D&quot;
-<strong>Output:</strong> 1
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == s.length</code></li>
-	<li><code>1 &lt;= n &lt;= 200</code></li>
-	<li><code>s[i]</code> is either <code>&#39;I&#39;</code> or <code>&#39;D&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
diff --git a/problems/valid-permutations-for-di-sequence/valid_permutations_for_di_sequence.go b/problems/valid-permutations-for-di-sequence/valid_permutations_for_di_sequence.go
deleted file mode 100644
index df0cf8f43..000000000
--- a/problems/valid-permutations-for-di-sequence/valid_permutations_for_di_sequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem903
diff --git a/problems/valid-permutations-for-di-sequence/valid_permutations_for_di_sequence_test.go b/problems/valid-permutations-for-di-sequence/valid_permutations_for_di_sequence_test.go
deleted file mode 100644
index df0cf8f43..000000000
--- a/problems/valid-permutations-for-di-sequence/valid_permutations_for_di_sequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem903
diff --git a/problems/valid-phone-numbers/README.md b/problems/valid-phone-numbers/README.md
deleted file mode 100644
index 0f7a3f58e..000000000
--- a/problems/valid-phone-numbers/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-frequency "Word Frequency")
-　　　　　　　　　　　　　　　　
-[Next >](../transpose-file "Transpose File")
-
-## [193. Valid Phone Numbers (Easy)](https://leetcode.com/problems/valid-phone-numbers "有效电话号码")
-
-<p>Given a text file <code>file.txt</code> that contains a list of phone numbers (one per line), write a one-liner bash script to print all valid phone numbers.</p>
-
-<p>You may assume that a valid phone number must appear in one of the following two formats: (xxx) xxx-xxxx or xxx-xxx-xxxx. (x means a digit)</p>
-
-<p>You may also assume each line in the text file must not contain leading or trailing white spaces.</p>
-
-<p><strong>Example:</strong></p>
-
-<p>Assume that <code>file.txt</code> has the following content:</p>
-
-<pre>
-987-123-4567
-123 456 7890
-(123) 456-7890
-</pre>
-
-<p>Your script should output the following valid phone numbers:</p>
-
-<pre>
-987-123-4567
-(123) 456-7890
-</pre>
-
-### Related Topics
-  [[Shell](../../tag/shell/README.md)]
diff --git a/problems/valid-phone-numbers/file.txt b/problems/valid-phone-numbers/file.txt
deleted file mode 100644
index ab5499cd4..000000000
--- a/problems/valid-phone-numbers/file.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-987-123-4567
-123 456 7890
-(123) 456-7890
diff --git a/problems/valid-phone-numbers/valid_phone_numbers.bash b/problems/valid-phone-numbers/valid_phone_numbers.bash
deleted file mode 100755
index ebdf6316c..000000000
--- a/problems/valid-phone-numbers/valid_phone_numbers.bash
+++ /dev/null
@@ -1,5 +0,0 @@
-#!/usr/bin/env bash
-
-# Read from the file file.txt and output all valid phone numbers to stdout.
-
-grep -P '^(\d{3}-|\(\d{3}\) )\d{3}-\d{4}$' file.txt
diff --git a/problems/valid-square/README.md b/problems/valid-square/README.md
deleted file mode 100644
index 0d0c4f5cb..000000000
--- a/problems/valid-square/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../fraction-addition-and-subtraction "Fraction Addition and Subtraction")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-harmonious-subsequence "Longest Harmonious Subsequence")
-
-## [593. Valid Square (Medium)](https://leetcode.com/problems/valid-square "有效的正方形")
-
-<p>Given the coordinates of four points in 2D space <code>p1</code>, <code>p2</code>, <code>p3</code> and <code>p4</code>, return <code>true</code> <em>if the four points construct a square</em>.</p>
-
-<p>The coordinate of a point <code>p<sub>i</sub></code> is represented as <code>[x<sub>i</sub>, y<sub>i</sub>]</code>. The input is <strong>not</strong> given in any order.</p>
-
-<p>A <strong>valid square</strong> has four equal sides with positive length and four equal angles (90-degree angles).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> p1 = [0,0], p2 = [1,1], p3 = [1,0], p4 = [0,1]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> p1 = [0,0], p2 = [1,1], p3 = [1,0], p4 = [0,12]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> p1 = [1,0], p2 = [-1,0], p3 = [0,1], p4 = [0,-1]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>p1.length == p2.length == p3.length == p4.length == 2</code></li>
-	<li><code>-10<sup>4</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Geometry](../../tag/geometry/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/valid-square/valid_square.go b/problems/valid-square/valid_square.go
deleted file mode 100644
index a70dcbcb8..000000000
--- a/problems/valid-square/valid_square.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem593
diff --git a/problems/valid-square/valid_square_test.go b/problems/valid-square/valid_square_test.go
deleted file mode 100644
index a70dcbcb8..000000000
--- a/problems/valid-square/valid_square_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem593
diff --git a/problems/valid-sudoku/README.md b/problems/valid-sudoku/README.md
deleted file mode 100644
index 0ede45b13..000000000
--- a/problems/valid-sudoku/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../search-insert-position "Search Insert Position")
-　　　　　　　　　　　　　　　　
-[Next >](../sudoku-solver "Sudoku Solver")
-
-## [36. Valid Sudoku (Medium)](https://leetcode.com/problems/valid-sudoku "有效的数独")
-
-<p>Determine if a&nbsp;<code>9 x 9</code> Sudoku board&nbsp;is valid.&nbsp;Only the filled cells need to be validated&nbsp;<strong>according to the following rules</strong>:</p>
-
-<ol>
-	<li>Each row&nbsp;must contain the&nbsp;digits&nbsp;<code>1-9</code> without repetition.</li>
-	<li>Each column must contain the digits&nbsp;<code>1-9</code>&nbsp;without repetition.</li>
-	<li>Each of the nine&nbsp;<code>3 x 3</code> sub-boxes of the grid must contain the digits&nbsp;<code>1-9</code>&nbsp;without repetition.</li>
-</ol>
-
-<p><strong>Note:</strong></p>
-
-<ul>
-	<li>A Sudoku board (partially filled) could be valid but is not necessarily solvable.</li>
-	<li>Only the filled cells need to be validated according to the mentioned&nbsp;rules.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img src="https://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Sudoku-by-L2G-20050714.svg/250px-Sudoku-by-L2G-20050714.svg.png" style="height:250px; width:250px" />
-<pre>
-<strong>Input:</strong> board = 
-[[&quot;5&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]
-,[&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;,&quot;9&quot;,&quot;5&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]
-,[&quot;.&quot;,&quot;9&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;]
-,[&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;3&quot;]
-,[&quot;4&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;]
-,[&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;]
-,[&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;8&quot;,&quot;.&quot;]
-,[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;4&quot;,&quot;1&quot;,&quot;9&quot;,&quot;.&quot;,&quot;.&quot;,&quot;5&quot;]
-,[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;9&quot;]]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> board = 
-[[&quot;8&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]
-,[&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;,&quot;9&quot;,&quot;5&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]
-,[&quot;.&quot;,&quot;9&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;]
-,[&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;3&quot;]
-,[&quot;4&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;]
-,[&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;]
-,[&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;8&quot;,&quot;.&quot;]
-,[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;4&quot;,&quot;1&quot;,&quot;9&quot;,&quot;.&quot;,&quot;.&quot;,&quot;5&quot;]
-,[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;9&quot;]]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> Same as Example 1, except with the <strong>5</strong> in the top left corner being modified to <strong>8</strong>. Since there are two 8&#39;s in the top left 3x3 sub-box, it is invalid.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>board.length == 9</code></li>
-	<li><code>board[i].length == 9</code></li>
-	<li><code>board[i][j]</code> is a digit <code>1-9</code> or <code>&#39;.&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Sudoku Solver](../sudoku-solver) (Hard)
diff --git a/problems/valid-sudoku/valid_sudoku.go b/problems/valid-sudoku/valid_sudoku.go
deleted file mode 100644
index d97cfea04..000000000
--- a/problems/valid-sudoku/valid_sudoku.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package problem36
-
-func isValidSudoku(board [][]byte) bool {
-	for i := 0; i < 9; i++ {
-		row := make(map[byte]bool)
-		col := make(map[byte]bool)
-		boxes := make(map[byte]bool)
-
-		for j := 0; j < 9; j++ {
-			if board[i][j] != '.' {
-				if row[board[i][j]] {
-					return false
-				}
-				row[board[i][j]] = true
-			}
-			if board[j][i] != '.' {
-				if col[board[j][i]] {
-					return false
-				}
-				col[board[j][i]] = true
-			}
-
-			if board[i/3*3+j/3][i%3*3+j%3] != '.' {
-				if boxes[board[i/3*3+j/3][i%3*3+j%3]] {
-					return false
-				}
-				boxes[board[i/3*3+j/3][i%3*3+j%3]] = true
-			}
-		}
-	}
-	return true
-}
diff --git a/problems/valid-sudoku/valid_sudoku_test.go b/problems/valid-sudoku/valid_sudoku_test.go
deleted file mode 100644
index 9c7b72fec..000000000
--- a/problems/valid-sudoku/valid_sudoku_test.go
+++ /dev/null
@@ -1,90 +0,0 @@
-package problem36
-
-import "testing"
-
-type testType struct {
-	in   [][]byte
-	want bool
-}
-
-func TestIsValidSudoku(t *testing.T) {
-	tests := [...]testType{
-		{
-			in: [][]byte{
-				{'5', '3', '.', '.', '7', '.', '.', '.', '.'},
-				{'6', '.', '.', '1', '9', '5', '.', '.', '.'},
-				{'.', '9', '8', '.', '.', '.', '.', '6', '.'},
-				{'8', '.', '.', '.', '6', '.', '.', '.', '3'},
-				{'4', '.', '.', '8', '.', '3', '.', '.', '1'},
-				{'7', '.', '.', '.', '2', '.', '.', '.', '6'},
-				{'.', '6', '.', '.', '.', '.', '2', '8', '.'},
-				{'.', '.', '.', '4', '1', '9', '.', '.', '5'},
-				{'.', '.', '.', '.', '8', '.', '.', '7', '9'},
-			},
-			want: true,
-		},
-		{
-			in: [][]byte{
-				{'5', '3', '6', '.', '7', '.', '.', '.', '.'},
-				{'6', '.', '.', '1', '9', '5', '.', '.', '.'},
-				{'.', '9', '8', '.', '.', '.', '.', '6', '.'},
-				{'8', '.', '.', '.', '6', '.', '.', '.', '3'},
-				{'4', '.', '.', '8', '.', '3', '.', '.', '1'},
-				{'7', '.', '.', '.', '2', '.', '.', '.', '6'},
-				{'.', '6', '.', '.', '.', '.', '2', '8', '.'},
-				{'.', '.', '.', '4', '1', '9', '.', '.', '5'},
-				{'.', '.', '.', '.', '8', '.', '.', '7', '9'},
-			},
-			want: false,
-		},
-		{
-			in: [][]byte{
-				{'8', '3', '.', '.', '7', '.', '.', '.', '.'},
-				{'6', '.', '.', '1', '9', '5', '.', '.', '.'},
-				{'.', '9', '8', '.', '.', '.', '.', '6', '.'},
-				{'8', '.', '.', '.', '6', '.', '.', '.', '3'},
-				{'4', '.', '.', '8', '.', '3', '.', '.', '1'},
-				{'7', '.', '.', '.', '2', '.', '.', '.', '6'},
-				{'.', '6', '.', '.', '.', '.', '2', '8', '.'},
-				{'.', '.', '.', '4', '1', '9', '.', '.', '5'},
-				{'.', '.', '.', '.', '8', '.', '.', '7', '9'},
-			},
-			want: false,
-		},
-		{
-			in: [][]byte{
-				{'8', '3', '.', '.', '3', '.', '.', '.', '.'},
-				{'6', '.', '.', '1', '9', '5', '.', '.', '.'},
-				{'.', '9', '2', '.', '.', '.', '.', '6', '.'},
-				{'1', '.', '.', '.', '6', '.', '.', '.', '3'},
-				{'4', '.', '.', '8', '.', '3', '.', '.', '1'},
-				{'7', '.', '.', '.', '2', '.', '.', '.', '6'},
-				{'.', '6', '.', '.', '.', '.', '2', '8', '.'},
-				{'.', '.', '.', '4', '1', '9', '.', '.', '5'},
-				{'.', '.', '.', '.', '8', '.', '.', '7', '9'},
-			},
-			want: false,
-		},
-		{
-			in: [][]byte{
-				{'8', '3', '.', '.', '3', '.', '.', '.', '.'},
-				{'6', '.', '.', '1', '9', '5', '.', '.', '.'},
-				{'.', '8', '2', '.', '.', '.', '.', '6', '.'},
-				{'1', '.', '.', '.', '6', '.', '.', '.', '3'},
-				{'4', '.', '.', '8', '.', '3', '.', '.', '1'},
-				{'7', '.', '.', '.', '2', '.', '.', '.', '6'},
-				{'.', '6', '.', '.', '.', '.', '2', '8', '.'},
-				{'.', '.', '.', '4', '1', '9', '.', '.', '5'},
-				{'.', '.', '.', '.', '8', '.', '.', '7', '9'},
-			},
-			want: false,
-		},
-	}
-
-	for _, tt := range tests {
-		got := isValidSudoku(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/valid-tic-tac-toe-state/README.md b/problems/valid-tic-tac-toe-state/README.md
deleted file mode 100644
index fde5d893b..000000000
--- a/problems/valid-tic-tac-toe-state/README.md
+++ /dev/null
@@ -1,74 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../preimage-size-of-factorial-zeroes-function "Preimage Size of Factorial Zeroes Function")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-subarrays-with-bounded-maximum "Number of Subarrays with Bounded Maximum")
-
-## [794. Valid Tic-Tac-Toe State (Medium)](https://leetcode.com/problems/valid-tic-tac-toe-state "有效的井字游戏")
-
-<p>Given a Tic-Tac-Toe board as a string array <code>board</code>, return <code>true</code> if and only if it is possible to reach this board position during the course of a valid tic-tac-toe game.</p>
-
-<p>The board is a <code>3 x 3</code> array that consists of characters <code>&#39; &#39;</code>, <code>&#39;X&#39;</code>, and <code>&#39;O&#39;</code>. The <code>&#39; &#39;</code> character represents an empty square.</p>
-
-<p>Here are the rules of Tic-Tac-Toe:</p>
-
-<ul>
-	<li>Players take turns placing characters into empty squares <code>&#39; &#39;</code>.</li>
-	<li>The first player always places <code>&#39;X&#39;</code> characters, while the second player always places <code>&#39;O&#39;</code> characters.</li>
-	<li><code>&#39;X&#39;</code> and <code>&#39;O&#39;</code> characters are always placed into empty squares, never filled ones.</li>
-	<li>The game ends when there are three of the same (non-empty) character filling any row, column, or diagonal.</li>
-	<li>The game also ends if all squares are non-empty.</li>
-	<li>No more moves can be played if the game is over.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe1-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> board = [&quot;O  &quot;,&quot;   &quot;,&quot;   &quot;]
-<strong>Output:</strong> false
-Explanation: The first player always plays &quot;X&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe2-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> board = [&quot;XOX&quot;,&quot; X &quot;,&quot;   &quot;]
-<strong>Output:</strong> false
-Explanation: Players take turns making moves.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe3-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> board = [&quot;XXX&quot;,&quot;   &quot;,&quot;OOO&quot;]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe4-grid.jpg" style="width: 253px; height: 253px;" />
-<pre>
-<strong>Input:</strong> board = [&quot;XOX&quot;,&quot;O O&quot;,&quot;XOX&quot;]
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>board.length == 3</code></li>
-	<li><code>board[i].length == 3</code></li>
-	<li><code>board[i][j]</code> is either <code>&#39;X&#39;</code>, <code>&#39;O&#39;</code>, or <code>&#39; &#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Design Tic-Tac-Toe](../design-tic-tac-toe) (Medium)
diff --git a/problems/valid-tic-tac-toe-state/valid_tic_tac_toe_state.go b/problems/valid-tic-tac-toe-state/valid_tic_tac_toe_state.go
deleted file mode 100644
index 1ba7472d9..000000000
--- a/problems/valid-tic-tac-toe-state/valid_tic_tac_toe_state.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem794
diff --git a/problems/valid-tic-tac-toe-state/valid_tic_tac_toe_state_test.go b/problems/valid-tic-tac-toe-state/valid_tic_tac_toe_state_test.go
deleted file mode 100644
index 1ba7472d9..000000000
--- a/problems/valid-tic-tac-toe-state/valid_tic_tac_toe_state_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem794
diff --git a/problems/valid-triangle-number/README.md b/problems/valid-triangle-number/README.md
deleted file mode 100644
index abf3295a3..000000000
--- a/problems/valid-triangle-number/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../triangle-judgement "Triangle Judgement")
-　　　　　　　　　　　　　　　　
-[Next >](../shortest-distance-in-a-plane "Shortest Distance in a Plane")
-
-## [611. Valid Triangle Number (Medium)](https://leetcode.com/problems/valid-triangle-number "有效三角形的个数")
-
-<p>Given an integer array <code>nums</code>, return <em>the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,2,3,4]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> Valid combinations are: 
-2,3,4 (using the first 2)
-2,3,4 (using the second 2)
-2,2,3
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [4,2,3,4]
-<strong>Output:</strong> 4
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [3Sum Smaller](../3sum-smaller) (Medium)
diff --git a/problems/valid-triangle-number/valid_triangle_number.go b/problems/valid-triangle-number/valid_triangle_number.go
deleted file mode 100644
index f5ada5238..000000000
--- a/problems/valid-triangle-number/valid_triangle_number.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem611
diff --git a/problems/valid-triangle-number/valid_triangle_number_test.go b/problems/valid-triangle-number/valid_triangle_number_test.go
deleted file mode 100644
index f5ada5238..000000000
--- a/problems/valid-triangle-number/valid_triangle_number_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem611
diff --git a/problems/valid-word-abbreviation/README.md b/problems/valid-word-abbreviation/README.md
deleted file mode 100644
index 63b929eb4..000000000
--- a/problems/valid-word-abbreviation/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../trapping-rain-water-ii "Trapping Rain Water II")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-palindrome "Longest Palindrome")
-
-## [408. Valid Word Abbreviation (Easy)](https://leetcode.com/problems/valid-word-abbreviation "有效单词缩写")
-
-<p>
-Given a <b>non-empty</b> string <code>s</code> and an abbreviation <code>abbr</code>, return whether the string matches with the given abbreviation.
-</p>
-
-<p>A string such as <code>"word"</code> contains only the following valid abbreviations:</p>
-
-<pre>["word", "1ord", "w1rd", "wo1d", "wor1", "2rd", "w2d", "wo2", "1o1d", "1or1", "w1r1", "1o2", "2r1", "3d", "w3", "4"]
-</pre>
-
-<p>Notice that only the above abbreviations are valid abbreviations of the string <code>"word"</code>. Any other string is not a valid abbreviation of <code>"word"</code>.</p>
-
-<p><b>Note:</b><br />
-Assume <code>s</code> contains only lowercase letters and <code>abbr</code> contains only lowercase letters and digits.
-</p>
-
-<p><b>Example 1:</b><br />
-<pre>
-Given <b>s</b> = "internationalization", <b>abbr</b> = "i12iz4n":
-
-Return true.
-</pre>
-</p>
-
-<p><b>Example 2:</b><br />
-<pre>
-Given <b>s</b> = "apple", <b>abbr</b> = "a2e":
-
-Return false.
-</pre>
-</p>
-
-### Related Topics
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Minimum Unique Word Abbreviation](../minimum-unique-word-abbreviation) (Hard)
-  1. [Word Abbreviation](../word-abbreviation) (Hard)
-  1. [Check if an Original String Exists Given Two Encoded Strings](../check-if-an-original-string-exists-given-two-encoded-strings) (Hard)
diff --git a/problems/valid-word-abbreviation/valid_word_abbreviation.go b/problems/valid-word-abbreviation/valid_word_abbreviation.go
deleted file mode 100644
index a77ddb9b4..000000000
--- a/problems/valid-word-abbreviation/valid_word_abbreviation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem408
diff --git a/problems/valid-word-abbreviation/valid_word_abbreviation_test.go b/problems/valid-word-abbreviation/valid_word_abbreviation_test.go
deleted file mode 100644
index a77ddb9b4..000000000
--- a/problems/valid-word-abbreviation/valid_word_abbreviation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem408
diff --git a/problems/valid-word-square/README.md b/problems/valid-word-square/README.md
deleted file mode 100644
index 82c857ad4..000000000
--- a/problems/valid-word-square/README.md
+++ /dev/null
@@ -1,98 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-xor-of-two-numbers-in-an-array "Maximum XOR of Two Numbers in an Array")
-　　　　　　　　　　　　　　　　
-[Next >](../reconstruct-original-digits-from-english "Reconstruct Original Digits from English")
-
-## [422. Valid Word Square (Easy)](https://leetcode.com/problems/valid-word-square "有效的单词方块")
-
-<p>Given a sequence of words, check whether it forms a valid word square.</p>
-
-<p>A sequence of words forms a valid word square if the <i>k</i><sup>th</sup> row and column read the exact same string, where 0 &le; <i>k</i> &lt; max(numRows, numColumns).</p>
-
-<p><b>Note:</b><br />
-<ol>
-<li>The number of words given is at least 1 and does not exceed 500.</li>
-<li>Word length will be at least 1 and does not exceed 500.</li>
-<li>Each word contains only lowercase English alphabet <code>a-z</code>.</li>
-</ol>
-</p>
-
-<p><b>Example 1:</b>
-<pre>
-<b>Input:</b>
-[
-  "abcd",
-  "bnrt",
-  "crmy",
-  "dtye"
-]
-
-<b>Output:</b>
-true
-
-<b>Explanation:</b>
-The first row and first column both read "abcd".
-The second row and second column both read "bnrt".
-The third row and third column both read "crmy".
-The fourth row and fourth column both read "dtye".
-
-Therefore, it is a valid word square.
-</pre>
-</p>
-
-<p><b>Example 2:</b>
-<pre>
-<b>Input:</b>
-[
-  "abcd",
-  "bnrt",
-  "crm",
-  "dt"
-]
-
-<b>Output:</b>
-true
-
-<b>Explanation:</b>
-The first row and first column both read "abcd".
-The second row and second column both read "bnrt".
-The third row and third column both read "crm".
-The fourth row and fourth column both read "dt".
-
-Therefore, it is a valid word square.
-</pre>
-</p>
-
-<p><b>Example 3:</b>
-<pre>
-<b>Input:</b>
-[
-  "ball",
-  "area",
-  "read",
-  "lady"
-]
-
-<b>Output:</b>
-false
-
-<b>Explanation:</b>
-The third row reads "read" while the third column reads "lead".
-
-Therefore, it is <b>NOT</b> a valid word square.
-</pre>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Word Squares](../word-squares) (Hard)
-  1. [Toeplitz Matrix](../toeplitz-matrix) (Easy)
diff --git a/problems/valid-word-square/valid_word_square.go b/problems/valid-word-square/valid_word_square.go
deleted file mode 100644
index 882839128..000000000
--- a/problems/valid-word-square/valid_word_square.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem422
diff --git a/problems/valid-word-square/valid_word_square_test.go b/problems/valid-word-square/valid_word_square_test.go
deleted file mode 100644
index 882839128..000000000
--- a/problems/valid-word-square/valid_word_square_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem422
diff --git a/problems/validate-binary-search-tree/README.md b/problems/validate-binary-search-tree/README.md
deleted file mode 100644
index 889fb70ee..000000000
--- a/problems/validate-binary-search-tree/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../interleaving-string "Interleaving String")
-　　　　　　　　　　　　　　　　
-[Next >](../recover-binary-search-tree "Recover Binary Search Tree")
-
-## [98. Validate Binary Search Tree (Medium)](https://leetcode.com/problems/validate-binary-search-tree "验证二叉搜索树")
-
-<p>Given the <code>root</code> of a binary tree, <em>determine if it is a valid binary search tree (BST)</em>.</p>
-
-<p>A <strong>valid BST</strong> is defined as follows:</p>
-
-<ul>
-	<li>The left subtree of a node contains only nodes with keys <strong>less than</strong> the node&#39;s key.</li>
-	<li>The right subtree of a node contains only nodes with keys <strong>greater than</strong> the node&#39;s key.</li>
-	<li>Both the left and right subtrees must also be binary search trees.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/01/tree1.jpg" style="width: 302px; height: 182px;" />
-<pre>
-<strong>Input:</strong> root = [2,1,3]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/12/01/tree2.jpg" style="width: 422px; height: 292px;" />
-<pre>
-<strong>Input:</strong> root = [5,1,4,null,null,3,6]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> The root node&#39;s value is 5 but its right child&#39;s value is 4.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
-	<li><code>-2<sup>31</sup> &lt;= Node.val &lt;= 2<sup>31</sup> - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Inorder Traversal](../binary-tree-inorder-traversal) (Easy)
-  1. [Find Mode in Binary Search Tree](../find-mode-in-binary-search-tree) (Easy)
diff --git a/problems/validate-binary-search-tree/validate_binary_search_tree.go b/problems/validate-binary-search-tree/validate_binary_search_tree.go
deleted file mode 100644
index 0aa9bf051..000000000
--- a/problems/validate-binary-search-tree/validate_binary_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem98
diff --git a/problems/validate-binary-search-tree/validate_binary_search_tree_test.go b/problems/validate-binary-search-tree/validate_binary_search_tree_test.go
deleted file mode 100644
index 0aa9bf051..000000000
--- a/problems/validate-binary-search-tree/validate_binary_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem98
diff --git a/problems/validate-binary-tree-nodes/README.md b/problems/validate-binary-tree-nodes/README.md
deleted file mode 100644
index a972d39a9..000000000
--- a/problems/validate-binary-tree-nodes/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-days-between-two-dates "Number of Days Between Two Dates")
-　　　　　　　　　　　　　　　　
-[Next >](../closest-divisors "Closest Divisors")
-
-## [1361. Validate Binary Tree Nodes (Medium)](https://leetcode.com/problems/validate-binary-tree-nodes "验证二叉树")
-
-<p>You have <code>n</code> binary tree nodes numbered from <code>0</code> to <code>n - 1</code> where node <code>i</code> has two children <code>leftChild[i]</code> and <code>rightChild[i]</code>, return <code>true</code> if and only if <strong>all</strong> the given nodes form <strong>exactly one</strong> valid binary tree.</p>
-
-<p>If node <code>i</code> has no left child then <code>leftChild[i]</code> will equal <code>-1</code>, similarly for the right child.</p>
-
-<p>Note that the nodes have no values and that we only use the node numbers in this problem.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/08/23/1503_ex1.png" style="width: 195px; height: 287px;" />
-<pre>
-<strong>Input:</strong> n = 4, leftChild = [1,-1,3,-1], rightChild = [2,-1,-1,-1]
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/08/23/1503_ex2.png" style="width: 183px; height: 272px;" />
-<pre>
-<strong>Input:</strong> n = 4, leftChild = [1,-1,3,-1], rightChild = [2,3,-1,-1]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/08/23/1503_ex3.png" style="width: 82px; height: 174px;" />
-<pre>
-<strong>Input:</strong> n = 2, leftChild = [1,0], rightChild = [-1,-1]
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2019/08/23/1503_ex4.png" style="width: 470px; height: 191px;" />
-<pre>
-<strong>Input:</strong> n = 6, leftChild = [1,-1,-1,4,-1,-1], rightChild = [2,-1,-1,5,-1,-1]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
-	<li><code>leftChild.length == rightChild.length == n</code></li>
-	<li><code>-1 &lt;= leftChild[i], rightChild[i] &lt;= n - 1</code></li>
-</ul>
-
-### Related Topics
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Union Find](../../tag/union-find/README.md)]
-  [[Graph](../../tag/graph/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Find the parent of each node.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-A valid tree must have nodes with only one parent and exactly one node with no parent.
-</details>
diff --git a/problems/validate-ip-address/README.md b/problems/validate-ip-address/README.md
deleted file mode 100644
index 9b8f41bc6..000000000
--- a/problems/validate-ip-address/README.md
+++ /dev/null
@@ -1,78 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../unique-substrings-in-wraparound-string "Unique Substrings in Wraparound String")
-　　　　　　　　　　　　　　　　
-[Next >](../convex-polygon "Convex Polygon")
-
-## [468. Validate IP Address (Medium)](https://leetcode.com/problems/validate-ip-address "验证IP地址")
-
-<p>Given a string <code>IP</code>, return <code>&quot;IPv4&quot;</code> if IP is a valid IPv4 address, <code>&quot;IPv6&quot;</code> if IP is a valid IPv6 address or <code>&quot;Neither&quot;</code> if IP is not a correct IP of any type.</p>
-
-<p><strong>A valid IPv4</strong> address is an IP in the form <code>&quot;x<sub>1</sub>.x<sub>2</sub>.x<sub>3</sub>.x<sub>4</sub>&quot;</code> where <code>0 &lt;= x<sub>i</sub> &lt;= 255</code> and <code>x<sub>i</sub></code> <strong>cannot contain</strong> leading zeros. For example, <code>&quot;192.168.1.1&quot;</code> and <code>&quot;192.168.1.0&quot;</code> are valid IPv4 addresses but <code>&quot;192.168.01.1&quot;</code>, while <code>&quot;192.168.1.00&quot;</code> and <code>&quot;192.168@1.1&quot;</code> are invalid IPv4 addresses.</p>
-
-<p><strong>A valid IPv6</strong> address is an IP in the form <code>&quot;x<sub>1</sub>:x<sub>2</sub>:x<sub>3</sub>:x<sub>4</sub>:x<sub>5</sub>:x<sub>6</sub>:x<sub>7</sub>:x<sub>8</sub>&quot;</code> where:</p>
-
-<ul>
-	<li><code>1 &lt;= x<sub>i</sub>.length &lt;= 4</code></li>
-	<li><code>x<sub>i</sub></code> is a <strong>hexadecimal string</strong> which may contain digits, lower-case English letter (<code>&#39;a&#39;</code> to <code>&#39;f&#39;</code>) and upper-case English letters (<code>&#39;A&#39;</code> to <code>&#39;F&#39;</code>).</li>
-	<li>Leading zeros are allowed in <code>x<sub>i</sub></code>.</li>
-</ul>
-
-<p>For example, &quot;<code>2001:0db8:85a3:0000:0000:8a2e:0370:7334&quot;</code> and &quot;<code>2001:db8:85a3:0:0:8A2E:0370:7334&quot;</code> are valid IPv6 addresses, while &quot;<code>2001:0db8:85a3::8A2E:037j:7334&quot;</code> and &quot;<code>02001:0db8:85a3:0000:0000:8a2e:0370:7334&quot;</code> are invalid IPv6 addresses.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> IP = &quot;172.16.254.1&quot;
-<strong>Output:</strong> &quot;IPv4&quot;
-<strong>Explanation:</strong> This is a valid IPv4 address, return &quot;IPv4&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> IP = &quot;2001:0db8:85a3:0:0:8A2E:0370:7334&quot;
-<strong>Output:</strong> &quot;IPv6&quot;
-<strong>Explanation:</strong> This is a valid IPv6 address, return &quot;IPv6&quot;.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> IP = &quot;256.256.256.256&quot;
-<strong>Output:</strong> &quot;Neither&quot;
-<strong>Explanation:</strong> This is neither a IPv4 address nor a IPv6 address.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> IP = &quot;2001:0db8:85a3:0:0:8A2E:0370:7334:&quot;
-<strong>Output:</strong> &quot;Neither&quot;
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> IP = &quot;1e1.4.5.6&quot;
-<strong>Output:</strong> &quot;Neither&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>IP</code> consists only of English letters, digits and the characters <code>&#39;.&#39;</code> and <code>&#39;:&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [IP to CIDR](../ip-to-cidr) (Medium)
diff --git a/problems/validate-ip-address/validate_ip_address.go b/problems/validate-ip-address/validate_ip_address.go
deleted file mode 100644
index 514ff90a4..000000000
--- a/problems/validate-ip-address/validate_ip_address.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package problem468
-
-import (
-	"net"
-	"regexp"
-)
-
-func validIPAddress(IP string) string {
-	if p4 := net.ParseIP(IP).To4(); len(p4) == net.IPv4len && p4.String() == IP {
-		return "IPv4"
-	} else if regexp.MustCompile(`^([0-9A-Fa-f]{1,4}:){7}[0-9A-Fa-f]{1,4}$`).MatchString(IP) {
-		return "IPv6"
-	}
-	return "Neither"
-}
diff --git a/problems/validate-ip-address/validate_ip_address_test.go b/problems/validate-ip-address/validate_ip_address_test.go
deleted file mode 100644
index 3dec640a4..000000000
--- a/problems/validate-ip-address/validate_ip_address_test.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package problem468
-
-import "testing"
-
-type testType struct {
-	in   string
-	want string
-}
-
-func TestValidIPAddress(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   "172.16.254.1",
-			want: "IPv4",
-		},
-		{
-			in:   "172.16.254.01",
-			want: "Neither",
-		},
-		{
-			in:   "256.256.256.256",
-			want: "Neither",
-		},
-		{
-			in:   "2001:0db8:85a3:0000:0000:8a2e:0370:7334",
-			want: "IPv6",
-		},
-		{
-			in:   "2001:db8:85a3:0:0:8A2E:0370:7334",
-			want: "IPv6",
-		},
-		{
-			in:   "2001:0db8:85a3::8A2E:0370:7334",
-			want: "Neither",
-		},
-		{
-			in:   "02001:0db8:85a3:0000:0000:8a2e:0370:7334",
-			want: "Neither",
-		},
-	}
-	for _, tt := range tests {
-		got := validIPAddress(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/validate-stack-sequences/README.md b/problems/validate-stack-sequences/README.md
deleted file mode 100644
index 8d88823e7..000000000
--- a/problems/validate-stack-sequences/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../minimum-increment-to-make-array-unique "Minimum Increment to Make Array Unique")
-　　　　　　　　　　　　　　　　
-[Next >](../most-stones-removed-with-same-row-or-column "Most Stones Removed with Same Row or Column")
-
-## [946. Validate Stack Sequences (Medium)](https://leetcode.com/problems/validate-stack-sequences "验证栈序列")
-
-<p>Given two integer arrays <code>pushed</code> and <code>popped</code> each with distinct values, return <code>true</code><em> if this could have been the result of a sequence of push and pop operations on an initially empty stack, or </em><code>false</code><em> otherwise.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> pushed = [1,2,3,4,5], popped = [4,5,3,2,1]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> We might do the following sequence:
-push(1), push(2), push(3), push(4),
-pop() -&gt; 4,
-push(5),
-pop() -&gt; 5, pop() -&gt; 3, pop() -&gt; 2, pop() -&gt; 1
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> pushed = [1,2,3,4,5], popped = [4,3,5,1,2]
-<strong>Output:</strong> false
-<strong>Explanation:</strong> 1 cannot be popped before 2.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= pushed.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= pushed[i] &lt;= 1000</code></li>
-	<li>All the elements of <code>pushed</code> are <strong>unique</strong>.</li>
-	<li><code>popped.length == pushed.length</code></li>
-	<li><code>popped</code> is a permutation of <code>pushed</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/validate-stack-sequences/validate_stack_sequences.go b/problems/validate-stack-sequences/validate_stack_sequences.go
deleted file mode 100644
index d209658ac..000000000
--- a/problems/validate-stack-sequences/validate_stack_sequences.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem946
diff --git a/problems/validate-stack-sequences/validate_stack_sequences_test.go b/problems/validate-stack-sequences/validate_stack_sequences_test.go
deleted file mode 100644
index d209658ac..000000000
--- a/problems/validate-stack-sequences/validate_stack_sequences_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem946
diff --git a/problems/verbal-arithmetic-puzzle/README.md b/problems/verbal-arithmetic-puzzle/README.md
deleted file mode 100644
index 6068accde..000000000
--- a/problems/verbal-arithmetic-puzzle/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../jump-game-iii "Jump Game III")
-　　　　　　　　　　　　　　　　
-[Next >](../running-total-for-different-genders "Running Total for Different Genders")
-
-## [1307. Verbal Arithmetic Puzzle (Hard)](https://leetcode.com/problems/verbal-arithmetic-puzzle "口算难题")
-
-<p>Given an equation, represented by <code>words</code> on the left side and the <code>result</code> on the right side.</p>
-
-<p>You need to check if the equation is solvable under the following rules:</p>
-
-<ul>
-	<li>Each character is decoded as one digit (0 - 9).</li>
-	<li>Every pair of different characters must map to different digits.</li>
-	<li>Each <code>words[i]</code> and <code>result</code> are decoded as one number <strong>without</strong> leading zeros.</li>
-	<li>Sum of numbers on the left side (<code>words</code>) will equal to the number on the right side (<code>result</code>).</li>
-</ul>
-
-<p>Return <code>true</code> <em>if the equation is solvable, otherwise return</em> <code>false</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;SEND&quot;,&quot;MORE&quot;], result = &quot;MONEY&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Map &#39;S&#39;-&gt; 9, &#39;E&#39;-&gt;5, &#39;N&#39;-&gt;6, &#39;D&#39;-&gt;7, &#39;M&#39;-&gt;1, &#39;O&#39;-&gt;0, &#39;R&#39;-&gt;8, &#39;Y&#39;-&gt;&#39;2&#39;
-Such that: &quot;SEND&quot; + &quot;MORE&quot; = &quot;MONEY&quot; ,  9567 + 1085 = 10652</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;SIX&quot;,&quot;SEVEN&quot;,&quot;SEVEN&quot;], result = &quot;TWENTY&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Map &#39;S&#39;-&gt; 6, &#39;I&#39;-&gt;5, &#39;X&#39;-&gt;0, &#39;E&#39;-&gt;8, &#39;V&#39;-&gt;7, &#39;N&#39;-&gt;2, &#39;T&#39;-&gt;1, &#39;W&#39;-&gt;&#39;3&#39;, &#39;Y&#39;-&gt;4
-Such that: &quot;SIX&quot; + &quot;SEVEN&quot; + &quot;SEVEN&quot; = &quot;TWENTY&quot; ,  650 + 68782 + 68782 = 138214</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;LEET&quot;,&quot;CODE&quot;], result = &quot;POINT&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= words.length &lt;= 5</code></li>
-	<li><code>1 &lt;= words[i].length, result.length &lt;= 7</code></li>
-	<li><code>words[i], result</code> contain only uppercase English letters.</li>
-	<li>The number of different characters used in the expression is at most <code>10</code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use Backtracking and pruning to solve this problem.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If you set the values of some digits (from right to left), the other digits will be constrained.
-</details>
diff --git a/problems/verify-preorder-sequence-in-binary-search-tree/README.md b/problems/verify-preorder-sequence-in-binary-search-tree/README.md
deleted file mode 100644
index 1eabfacad..000000000
--- a/problems/verify-preorder-sequence-in-binary-search-tree/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../factor-combinations "Factor Combinations")
-　　　　　　　　　　　　　　　　
-[Next >](../paint-house "Paint House")
-
-## [255. Verify Preorder Sequence in Binary Search Tree (Medium)](https://leetcode.com/problems/verify-preorder-sequence-in-binary-search-tree "验证前序遍历序列二叉搜索树")
-
-<p>Given an array of numbers, verify whether it is the correct preorder traversal sequence of a binary search tree.</p>
-
-<p>You may assume each number in the sequence is unique.</p>
-
-<p>Consider the following&nbsp;binary search tree:&nbsp;</p>
-
-<pre>
-     5
-    / \
-   2   6
-  / \
- 1   3</pre>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> [5,2,6,1,3]
-<strong>Output:</strong> false</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> [5,2,1,3,6]
-<strong>Output:</strong> true</pre>
-
-<p><b>Follow up:</b><br />
-Could you do it using only constant space complexity?</p>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Binary Search Tree](../../tag/binary-search-tree/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[Monotonic Stack](../../tag/monotonic-stack/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
-
-### Similar Questions
-  1. [Binary Tree Preorder Traversal](../binary-tree-preorder-traversal) (Easy)
diff --git a/problems/verify-preorder-sequence-in-binary-search-tree/verify_preorder_sequence_in_binary_search_tree.go b/problems/verify-preorder-sequence-in-binary-search-tree/verify_preorder_sequence_in_binary_search_tree.go
deleted file mode 100644
index 30756c85b..000000000
--- a/problems/verify-preorder-sequence-in-binary-search-tree/verify_preorder_sequence_in_binary_search_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem255
diff --git a/problems/verify-preorder-sequence-in-binary-search-tree/verify_preorder_sequence_in_binary_search_tree_test.go b/problems/verify-preorder-sequence-in-binary-search-tree/verify_preorder_sequence_in_binary_search_tree_test.go
deleted file mode 100644
index 30756c85b..000000000
--- a/problems/verify-preorder-sequence-in-binary-search-tree/verify_preorder_sequence_in_binary_search_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem255
diff --git a/problems/verify-preorder-serialization-of-a-binary-tree/README.md b/problems/verify-preorder-serialization-of-a-binary-tree/README.md
deleted file mode 100644
index b598c3005..000000000
--- a/problems/verify-preorder-serialization-of-a-binary-tree/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../patching-array "Patching Array")
-　　　　　　　　　　　　　　　　
-[Next >](../reconstruct-itinerary "Reconstruct Itinerary")
-
-## [331. Verify Preorder Serialization of a Binary Tree (Medium)](https://leetcode.com/problems/verify-preorder-serialization-of-a-binary-tree "验证二叉树的前序序列化")
-
-<p>One way to serialize a binary tree is to use <strong>preorder traversal</strong>. When we encounter a non-null node, we record the node&#39;s value. If it is a null node, we record using a sentinel value such as <code>&#39;#&#39;</code>.</p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/03/12/pre-tree.jpg" style="width: 362px; height: 293px;" />
-<p>For example, the above binary tree can be serialized to the string <code>&quot;9,3,4,#,#,1,#,#,2,#,6,#,#&quot;</code>, where <code>&#39;#&#39;</code> represents a null node.</p>
-
-<p>Given a string of comma-separated values <code>preorder</code>, return <code>true</code> if it is a correct preorder traversal serialization of a binary tree.</p>
-
-<p>It is <strong>guaranteed</strong> that each comma-separated value in the string must be either an integer or a character <code>&#39;#&#39;</code> representing null pointer.</p>
-
-<p>You may assume that the input format is always valid.</p>
-
-<ul>
-	<li>For example, it could never contain two consecutive commas, such as <code>&quot;1,,3&quot;</code>.</li>
-</ul>
-
-<p><strong>Note:&nbsp;</strong>You are not allowed to reconstruct the tree.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> preorder = "9,3,4,#,#,1,#,#,2,#,6,#,#"
-<strong>Output:</strong> true
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> preorder = "1,#"
-<strong>Output:</strong> false
-</pre><p><strong>Example 3:</strong></p>
-<pre><strong>Input:</strong> preorder = "9,#,#,1"
-<strong>Output:</strong> false
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= preorder.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>preorder</code> consist of integers in the range <code>[0, 100]</code> and <code>&#39;#&#39;</code> separated by commas <code>&#39;,&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Stack](../../tag/stack/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/verify-preorder-serialization-of-a-binary-tree/verify_preorder_serialization_of_a_binary_tree.go b/problems/verify-preorder-serialization-of-a-binary-tree/verify_preorder_serialization_of_a_binary_tree.go
deleted file mode 100644
index ded360cb7..000000000
--- a/problems/verify-preorder-serialization-of-a-binary-tree/verify_preorder_serialization_of_a_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem331
diff --git a/problems/verify-preorder-serialization-of-a-binary-tree/verify_preorder_serialization_of_a_binary_tree_test.go b/problems/verify-preorder-serialization-of-a-binary-tree/verify_preorder_serialization_of_a_binary_tree_test.go
deleted file mode 100644
index ded360cb7..000000000
--- a/problems/verify-preorder-serialization-of-a-binary-tree/verify_preorder_serialization_of_a_binary_tree_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem331
diff --git a/problems/verifying-an-alien-dictionary/README.md b/problems/verifying-an-alien-dictionary/README.md
deleted file mode 100644
index be804f1c7..000000000
--- a/problems/verifying-an-alien-dictionary/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../largest-component-size-by-common-factor "Largest Component Size by Common Factor")
-　　　　　　　　　　　　　　　　
-[Next >](../array-of-doubled-pairs "Array of Doubled Pairs")
-
-## [953. Verifying an Alien Dictionary (Easy)](https://leetcode.com/problems/verifying-an-alien-dictionary "验证外星语词典")
-
-<p>In an alien language, surprisingly, they also use English lowercase letters, but possibly in a different <code>order</code>. The <code>order</code> of the alphabet is some permutation of lowercase letters.</p>
-
-<p>Given a sequence of <code>words</code> written in the alien language, and the <code>order</code> of the alphabet, return <code>true</code> if and only if the given <code>words</code> are sorted lexicographically in this alien language.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;hello&quot;,&quot;leetcode&quot;], order = &quot;hlabcdefgijkmnopqrstuvwxyz&quot;
-<strong>Output:</strong> true
-<strong>Explanation: </strong>As &#39;h&#39; comes before &#39;l&#39; in this language, then the sequence is sorted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;word&quot;,&quot;world&quot;,&quot;row&quot;], order = &quot;worldabcefghijkmnpqstuvxyz&quot;
-<strong>Output:</strong> false
-<strong>Explanation: </strong>As &#39;d&#39; comes after &#39;l&#39; in this language, then words[0] &gt; words[1], hence the sequence is unsorted.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> words = [&quot;apple&quot;,&quot;app&quot;], order = &quot;abcdefghijklmnopqrstuvwxyz&quot;
-<strong>Output:</strong> false
-<strong>Explanation: </strong>The first three characters &quot;app&quot; match, and the second string is shorter (in size.) According to lexicographical rules &quot;apple&quot; &gt; &quot;app&quot;, because &#39;l&#39; &gt; &#39;&empty;&#39;, where &#39;&empty;&#39; is defined as the blank character which is less than any other character (<a href="https://en.wikipedia.org/wiki/Lexicographical_order" target="_blank">More info</a>).
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words.length &lt;= 100</code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 20</code></li>
-	<li><code>order.length == 26</code></li>
-	<li>All characters in <code>words[i]</code> and <code>order</code> are English lowercase letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/verifying-an-alien-dictionary/verifying_an_alien_dictionary.go b/problems/verifying-an-alien-dictionary/verifying_an_alien_dictionary.go
deleted file mode 100644
index 62345ee09..000000000
--- a/problems/verifying-an-alien-dictionary/verifying_an_alien_dictionary.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package problem953
-
-func isAlienSorted(words []string, order string) bool {
-	m := make(map[byte]int)
-	for i := len(order) - 1; i >= 0; i-- {
-		m[order[i]] = i
-	}
-	if len(words) > 1 {
-		for pre, word := range words[1:] {
-			l, wl := len(words[pre]), len(word)
-			for i := 0; i < l; i++ {
-				if wl <= i || m[words[pre][i]] > m[word[i]] {
-					return false
-				} else if m[words[pre][i]] < m[word[i]] {
-					break
-				}
-			}
-		}
-	}
-	return true
-}
diff --git a/problems/verifying-an-alien-dictionary/verifying_an_alien_dictionary_test.go b/problems/verifying-an-alien-dictionary/verifying_an_alien_dictionary_test.go
deleted file mode 100644
index 60f69fba5..000000000
--- a/problems/verifying-an-alien-dictionary/verifying_an_alien_dictionary_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem953
-
-import "testing"
-
-type testType struct {
-	words []string
-	order string
-	want  bool
-}
-
-func TestIsAlienSorted(t *testing.T) {
-	tests := [...]testType{
-		{
-			words: []string{"hello", "leetcode"},
-			order: "hlabcdefgijkmnopqrstuvwxyz",
-			want:  true,
-		},
-		{
-			words: []string{"word", "world", "row"},
-			order: "worldabcefghijkmnpqstuvxyz",
-			want:  false,
-		},
-		{
-			words: []string{"apple", "app"},
-			order: "abcdefghijklmnopqrstuvwxyz",
-			want:  false,
-		},
-	}
-	for _, tt := range tests {
-		got := isAlienSorted(tt.words, tt.order)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.words, got, tt.want)
-		}
-	}
-}
diff --git a/problems/vertical-order-traversal-of-a-binary-tree/README.md b/problems/vertical-order-traversal-of-a-binary-tree/README.md
deleted file mode 100644
index b82b15314..000000000
--- a/problems/vertical-order-traversal-of-a-binary-tree/README.md
+++ /dev/null
@@ -1,72 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../interval-list-intersections "Interval List Intersections")
-　　　　　　　　　　　　　　　　
-[Next >](../smallest-string-starting-from-leaf "Smallest String Starting From Leaf")
-
-## [987. Vertical Order Traversal of a Binary Tree (Hard)](https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree "二叉树的垂序遍历")
-
-<p>Given the <code>root</code> of a binary tree, calculate the <strong>vertical order traversal</strong> of the binary tree.</p>
-
-<p>For each node at position <code>(row, col)</code>, its left and right children will be at positions <code>(row + 1, col - 1)</code> and <code>(row + 1, col + 1)</code> respectively. The root of the tree is at <code>(0, 0)</code>.</p>
-
-<p>The <strong>vertical order traversal</strong> of a binary tree is a list of top-to-bottom orderings for each column index starting from the leftmost column and ending on the rightmost column. There may be multiple nodes in the same row and same column. In such a case, sort these nodes by their values.</p>
-
-<p>Return <em>the <strong>vertical order traversal</strong> of the binary tree</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/29/vtree1.jpg" style="width: 431px; height: 304px;" />
-<pre>
-<strong>Input:</strong> root = [3,9,20,null,null,15,7]
-<strong>Output:</strong> [[9],[3,15],[20],[7]]
-<strong>Explanation:</strong>
-Column -1: Only node 9 is in this column.
-Column 0: Nodes 3 and 15 are in this column in that order from top to bottom.
-Column 1: Only node 20 is in this column.
-Column 2: Only node 7 is in this column.</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/29/vtree2.jpg" style="width: 512px; height: 304px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,5,6,7]
-<strong>Output:</strong> [[4],[2],[1,5,6],[3],[7]]
-<strong>Explanation:</strong>
-Column -2: Only node 4 is in this column.
-Column -1: Only node 2 is in this column.
-Column 0: Nodes 1, 5, and 6 are in this column.
-          1 is at the top, so it comes first.
-          5 and 6 are at the same position (2, 0), so we order them by their value, 5 before 6.
-Column 1: Only node 3 is in this column.
-Column 2: Only node 7 is in this column.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2021/01/29/vtree3.jpg" style="width: 512px; height: 304px;" />
-<pre>
-<strong>Input:</strong> root = [1,2,3,4,6,5,7]
-<strong>Output:</strong> [[4],[2],[1,5,6],[3],[7]]
-<strong>Explanation:</strong>
-This case is the exact same as example 2, but with nodes 5 and 6 swapped.
-Note that the solution remains the same since 5 and 6 are in the same location and should be ordered by their values.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li>The number of nodes in the tree is in the range <code>[1, 1000]</code>.</li>
-	<li><code>0 &lt;= Node.val &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Tree](../../tag/tree/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Binary Tree](../../tag/binary-tree/README.md)]
diff --git a/problems/vertical-order-traversal-of-a-binary-tree/vertical_order_traversal_of_a_binary_tree.go b/problems/vertical-order-traversal-of-a-binary-tree/vertical_order_traversal_of_a_binary_tree.go
deleted file mode 100644
index 5f009a048..000000000
--- a/problems/vertical-order-traversal-of-a-binary-tree/vertical_order_traversal_of_a_binary_tree.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem987
diff --git a/problems/video-stitching/README.md b/problems/video-stitching/README.md
deleted file mode 100644
index bc7031855..000000000
--- a/problems/video-stitching/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../camelcase-matching "Camelcase Matching")
-　　　　　　　　　　　　　　　　
-[Next >](../divisor-game "Divisor Game")
-
-## [1024. Video Stitching (Medium)](https://leetcode.com/problems/video-stitching "视频拼接")
-
-<p>You are given a series of video clips from a sporting event that lasted <code>time</code> seconds. These video clips can be overlapping with each other and have varying lengths.</p>
-
-<p>Each video clip is described by an array <code>clips</code> where <code>clips[i] = [start<sub>i</sub>, end<sub>i</sub>]</code> indicates that the ith clip started at <code>start<sub>i</sub></code> and ended at <code>end<sub>i</sub></code>.</p>
-
-<p>We can cut these clips into segments freely.</p>
-
-<ul>
-	<li>For example, a clip <code>[0, 7]</code> can be cut into segments <code>[0, 1] + [1, 3] + [3, 7]</code>.</li>
-</ul>
-
-<p>Return <em>the minimum number of clips needed so that we can cut the clips into segments that cover the entire sporting event</em> <code>[0, time]</code>. If the task is impossible, return <code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> clips = [[0,2],[4,6],[8,10],[1,9],[1,5],[5,9]], time = 10
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We take the clips [0,2], [8,10], [1,9]; a total of 3 clips.
-Then, we can reconstruct the sporting event as follows:
-We cut [1,9] into segments [1,2] + [2,8] + [8,9].
-Now we have segments [0,2] + [2,8] + [8,10] which cover the sporting event [0, 10].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> clips = [[0,1],[1,2]], time = 5
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> We cannot cover [0,5] with only [0,1] and [1,2].
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> clips = [[0,1],[6,8],[0,2],[5,6],[0,4],[0,3],[6,7],[1,3],[4,7],[1,4],[2,5],[2,6],[3,4],[4,5],[5,7],[6,9]], time = 9
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> We can take clips [0,4], [4,7], and [6,9].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= clips.length &lt;= 100</code></li>
-	<li><code>0 &lt;= start<sub>i</sub> &lt;= end<sub>i</sub> &lt;= 100</code></li>
-	<li><code>1 &lt;= time &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What if we sort the intervals?  Considering the sorted intervals, how can we solve the problem with dynamic programming?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Let's consider a DP(pos, limit) where pos represents the position of the current interval we are gonna take the decision and limit is the current covered area from [0 - limit]. This DP returns the minimum number of taken intervals or infinite if it's not possible to cover the [0 - T] section.
-</details>
diff --git a/problems/video-stitching/video_stitching.go b/problems/video-stitching/video_stitching.go
deleted file mode 100644
index 2c1da3f0f..000000000
--- a/problems/video-stitching/video_stitching.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package problem1024
-
-import "sort"
-
-func videoStitching(clips [][]int, T int) int {
-	sort.Slice(clips, func(i int, j int) bool {
-		return clips[i][0] < clips[j][0]
-	})
-
-	res := 0
-
-	for i, start, end := 0, 0, 0; start < T; start = end {
-		for i < len(clips) && clips[i][0] <= start {
-			end = max(end, clips[i][1])
-			i++
-		}
-		if start == end {
-			return -1
-		}
-		res++
-	}
-
-	return res
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/problems/vowel-spellchecker/README.md b/problems/vowel-spellchecker/README.md
deleted file mode 100644
index b63489799..000000000
--- a/problems/vowel-spellchecker/README.md
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../univalued-binary-tree "Univalued Binary Tree")
-　　　　　　　　　　　　　　　　
-[Next >](../numbers-with-same-consecutive-differences "Numbers With Same Consecutive Differences")
-
-## [966. Vowel Spellchecker (Medium)](https://leetcode.com/problems/vowel-spellchecker "元音拼写检查器")
-
-<p>Given a <code>wordlist</code>, we want to implement a spellchecker that converts a query word into a correct word.</p>
-
-<p>For a given <code>query</code> word, the spell checker handles two categories of spelling mistakes:</p>
-
-<ul>
-	<li>Capitalization: If the query matches a word in the wordlist (<strong>case-insensitive</strong>), then the query word is returned with the same case as the case in the wordlist.
-	<ul>
-		<li>Example: <code>wordlist = [&quot;yellow&quot;]</code>, <code>query = &quot;YellOw&quot;</code>: <code>correct = &quot;yellow&quot;</code></li>
-		<li>Example: <code>wordlist = [&quot;Yellow&quot;]</code>, <code>query = &quot;yellow&quot;</code>: <code>correct = &quot;Yellow&quot;</code></li>
-		<li>Example: <code>wordlist = [&quot;yellow&quot;]</code>, <code>query = &quot;yellow&quot;</code>: <code>correct = &quot;yellow&quot;</code></li>
-	</ul>
-	</li>
-	<li>Vowel Errors: If after replacing the vowels <code>(&#39;a&#39;, &#39;e&#39;, &#39;i&#39;, &#39;o&#39;, &#39;u&#39;)</code> of the query word with any vowel individually, it matches a word in the wordlist (<strong>case-insensitive</strong>), then the query word is returned with the same case as the match in the wordlist.
-	<ul>
-		<li>Example: <code>wordlist = [&quot;YellOw&quot;]</code>, <code>query = &quot;yollow&quot;</code>: <code>correct = &quot;YellOw&quot;</code></li>
-		<li>Example: <code>wordlist = [&quot;YellOw&quot;]</code>, <code>query = &quot;yeellow&quot;</code>: <code>correct = &quot;&quot;</code> (no match)</li>
-		<li>Example: <code>wordlist = [&quot;YellOw&quot;]</code>, <code>query = &quot;yllw&quot;</code>: <code>correct = &quot;&quot;</code> (no match)</li>
-	</ul>
-	</li>
-</ul>
-
-<p>In addition, the spell checker operates under the following precedence rules:</p>
-
-<ul>
-	<li>When the query exactly matches a word in the wordlist (<strong>case-sensitive</strong>), you should return the same word back.</li>
-	<li>When the query matches a word up to capitlization, you should return the first such match in the wordlist.</li>
-	<li>When the query matches a word up to vowel errors, you should return the first such match in the wordlist.</li>
-	<li>If the query has no matches in the wordlist, you should return the empty string.</li>
-</ul>
-
-<p>Given some <code>queries</code>, return a list of words <code>answer</code>, where <code>answer[i]</code> is the correct word for <code>query = queries[i]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<pre><strong>Input:</strong> wordlist = ["KiTe","kite","hare","Hare"], queries = ["kite","Kite","KiTe","Hare","HARE","Hear","hear","keti","keet","keto"]
-<strong>Output:</strong> ["kite","KiTe","KiTe","Hare","hare","","","KiTe","","KiTe"]
-</pre><p><strong>Example 2:</strong></p>
-<pre><strong>Input:</strong> wordlist = ["yellow"], queries = ["YellOw"]
-<strong>Output:</strong> ["yellow"]
-</pre>
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= wordlist.length, queries.length &lt;= 5000</code></li>
-	<li><code>1 &lt;= wordlist[i].length, queries[i].length &lt;= 7</code></li>
-	<li><code>wordlist[i]</code> and <code>queries[i]</code> consist only of only English letters.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/vowel-spellchecker/vowel_spellchecker.go b/problems/vowel-spellchecker/vowel_spellchecker.go
deleted file mode 100644
index a6f485bae..000000000
--- a/problems/vowel-spellchecker/vowel_spellchecker.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem966
diff --git a/problems/vowels-of-all-substrings/README.md b/problems/vowels-of-all-substrings/README.md
deleted file mode 100644
index a508e72c8..000000000
--- a/problems/vowels-of-all-substrings/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-vowel-substrings-of-a-string "Count Vowel Substrings of a String")
-　　　　　　　　　　　　　　　　
-[Next >](../minimized-maximum-of-products-distributed-to-any-store "Minimized Maximum of Products Distributed to Any Store")
-
-## [2063. Vowels of All Substrings (Medium)](https://leetcode.com/problems/vowels-of-all-substrings "所有子字符串中的元音")
-
-<p>Given a string <code>word</code>, return <em>the <strong>sum of the number of vowels</strong> (</em><code>&#39;a&#39;</code>, <code>&#39;e&#39;</code><em>,</em> <code>&#39;i&#39;</code><em>,</em> <code>&#39;o&#39;</code><em>, and</em> <code>&#39;u&#39;</code><em>)</em> <em>in every substring of </em><code>word</code>.</p>
-
-<p>A <strong>substring</strong> is a contiguous (non-empty) sequence of characters within a string.</p>
-
-<p><strong>Note:</strong> Due to the large constraints, the answer may not fit in a signed 32-bit integer. Please be careful during the calculations.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;aba&quot;
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> 
-All possible substrings are: &quot;a&quot;, &quot;ab&quot;, &quot;aba&quot;, &quot;b&quot;, &quot;ba&quot;, and &quot;a&quot;.
-- &quot;b&quot; has 0 vowels in it
-- &quot;a&quot;, &quot;ab&quot;, &quot;ba&quot;, and &quot;a&quot; have 1 vowel each
-- &quot;aba&quot; has 2 vowels in it
-Hence, the total sum of vowels = 0 + 1 + 1 + 1 + 1 + 2 = 6. 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;abc&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> 
-All possible substrings are: &quot;a&quot;, &quot;ab&quot;, &quot;abc&quot;, &quot;b&quot;, &quot;bc&quot;, and &quot;c&quot;.
-- &quot;a&quot;, &quot;ab&quot;, and &quot;abc&quot; have 1 vowel each
-- &quot;b&quot;, &quot;bc&quot;, and &quot;c&quot; have 0 vowels each
-Hence, the total sum of vowels = 1 + 1 + 1 + 0 + 0 + 0 = 3.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> word = &quot;ltcd&quot;
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There are no vowels in any substring of &quot;ltcd&quot;.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= word.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>word</code> consists of lowercase English letters.</li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Combinatorics](../../tag/combinatorics/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Since generating substrings is not an option, can we count the number of substrings a vowel appears in?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-How much does each vowel contribute to the total sum?
-</details>
diff --git a/problems/walking-robot-simulation-ii/README.md b/problems/walking-robot-simulation-ii/README.md
deleted file mode 100644
index 89f18a29f..000000000
--- a/problems/walking-robot-simulation-ii/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../check-whether-two-strings-are-almost-equivalent "Check Whether Two Strings are Almost Equivalent")
-　　　　　　　　　　　　　　　　
-[Next >](../most-beautiful-item-for-each-query "Most Beautiful Item for Each Query")
-
-## [2069. Walking Robot Simulation II (Medium)](https://leetcode.com/problems/walking-robot-simulation-ii "模拟行走机器人 II")
-
-<p>A <code>width x height</code> grid is on an XY-plane with the <strong>bottom-left</strong> cell at <code>(0, 0)</code> and the <strong>top-right</strong> cell at <code>(width - 1, height - 1)</code>. The grid is aligned with the four cardinal directions (<code>&quot;North&quot;</code>, <code>&quot;East&quot;</code>, <code>&quot;South&quot;</code>, and <code>&quot;West&quot;</code>). A robot is <strong>initially</strong> at cell <code>(0, 0)</code> facing direction <code>&quot;East&quot;</code>.</p>
-
-<p>The robot can be instructed to move for a specific number of <strong>steps</strong>. For each step, it does the following.</p>
-
-<ol>
-	<li>Attempts to move <strong>forward one</strong> cell in the direction it is facing.</li>
-	<li>If the cell the robot is <strong>moving to</strong> is <strong>out of bounds</strong>, the robot instead <strong>turns</strong> 90 degrees <strong>counterclockwise</strong> and retries the step.</li>
-</ol>
-
-<p>After the robot finishes moving the number of steps required, it stops and awaits the next instruction.</p>
-
-<p>Implement the <code>Robot</code> class:</p>
-
-<ul>
-	<li><code>Robot(int width, int height)</code> Initializes the <code>width x height</code> grid with the robot at <code>(0, 0)</code> facing <code>&quot;East&quot;</code>.</li>
-	<li><code>void step(int num)</code> Instructs the robot to move forward <code>num</code> steps.</li>
-	<li><code>int[] getPos()</code> Returns the current cell the robot is at, as an array of length 2, <code>[x, y]</code>.</li>
-	<li><code>String getDir()</code> Returns the current direction of the robot, <code>&quot;North&quot;</code>, <code>&quot;East&quot;</code>, <code>&quot;South&quot;</code>, or <code>&quot;West&quot;</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="example-1" src="https://assets.leetcode.com/uploads/2021/10/09/example-1.png" style="width: 498px; height: 268px;" />
-<pre>
-<strong>Input</strong>
-[&quot;Robot&quot;, &quot;move&quot;, &quot;move&quot;, &quot;getPos&quot;, &quot;getDir&quot;, &quot;move&quot;, &quot;move&quot;, &quot;move&quot;, &quot;getPos&quot;, &quot;getDir&quot;]
-[[6, 3], [2], [2], [], [], [2], [1], [4], [], []]
-<strong>Output</strong>
-[null, null, null, [4, 0], &quot;East&quot;, null, null, null, [1, 2], &quot;West&quot;]
-
-<strong>Explanation</strong>
-Robot robot = new Robot(6, 3); // Initialize the grid and the robot at (0, 0) facing East.
-robot.move(2);  // It moves two steps East to (2, 0), and faces East.
-robot.move(2);  // It moves two steps East to (4, 0), and faces East.
-robot.getPos(); // return [4, 0]
-robot.getDir(); // return &quot;East&quot;
-robot.move(2);  // It moves one step East to (5, 0), and faces East.
-                // Moving the next step East would be out of bounds, so it turns and faces North.
-                // Then, it moves one step North to (5, 1), and faces North.
-robot.move(1);  // It moves one step North to (5, 2), and faces <strong>North</strong> (not West).
-robot.move(4);  // Moving the next step North would be out of bounds, so it turns and faces West.
-                // Then, it moves four steps West to (1, 2), and faces West.
-robot.getPos(); // return [1, 2]
-robot.getDir(); // return &quot;West&quot;
-
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>2 &lt;= width, height &lt;= 100</code></li>
-	<li><code>1 &lt;= num &lt;= 10<sup>5</sup></code></li>
-	<li>At most <code>10<sup>4</sup></code> calls <strong>in total</strong> will be made to <code>step</code>, <code>getPos</code>, and <code>getDir</code>.</li>
-</ul>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The robot only moves along the perimeter of the grid. Can you think if modulus can help you quickly compute which cell it stops at?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-After the robot moves one time, whenever the robot stops at some cell, it will always face a specific direction. i.e., The direction it faces is determined by the cell it stops at.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Can you precompute what direction it faces when it stops at each cell along the perimeter, and reuse the results?
-</details>
diff --git a/problems/walking-robot-simulation/README.md b/problems/walking-robot-simulation/README.md
deleted file mode 100644
index d73a44053..000000000
--- a/problems/walking-robot-simulation/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../length-of-longest-fibonacci-subsequence "Length of Longest Fibonacci Subsequence")
-　　　　　　　　　　　　　　　　
-[Next >](../koko-eating-bananas "Koko Eating Bananas")
-
-## [874. Walking Robot Simulation (Easy)](https://leetcode.com/problems/walking-robot-simulation "模拟行走机器人")
-
-<p>A robot on an infinite XY-plane starts at point <code>(0, 0)</code> and faces north. The robot can receive one of three possible types of <code>commands</code>:</p>
-
-<ul>
-	<li><code>-2</code>: turn left <code>90</code> degrees,</li>
-	<li><code>-1</code>: turn right <code>90</code> degrees, or</li>
-	<li><code>1 &lt;= k &lt;= 9</code>: move forward <code>k</code> units.</li>
-</ul>
-
-<p>Some of the grid squares are <code>obstacles</code>. The <code>i<sup>th</sup></code> obstacle is at grid point <code>obstacles[i] = (x<sub>i</sub>, y<sub>i</sub>)</code>.</p>
-
-<p>If the robot would try to move onto them, the robot stays on the previous grid square instead (but still continues following the rest of the route.)</p>
-
-<p>Return <em>the maximum Euclidean distance that the robot will be from the origin <strong>squared</strong> (i.e. if the distance is </em><code>5</code><em>, return </em><code>25</code><em>)</em>.</p>
-
-<p><strong>Note:</strong></p>
-
-<ul>
-	<li>North means +Y direction.</li>
-	<li>East means +X direction.</li>
-	<li>South means -Y direction.</li>
-	<li>West means -X direction.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> commands = [4,-1,3], obstacles = []
-<strong>Output:</strong> 25
-<strong>Explanation:</strong> The robot starts at (0, 0):
-1. Move north 4 units to (0, 4).
-2. Turn right.
-3. Move east 3 units to (3, 4).
-The furthest point away from the origin is (3, 4), which is 3<sup>2</sup> + 4<sup>2</sup> = 25 units away.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> commands = [4,-1,4,-2,4], obstacles = [[2,4]]
-<strong>Output:</strong> 65
-<strong>Explanation:</strong> The robot starts at (0, 0):
-1. Move north 4 units to (0, 4).
-2. Turn right.
-3. Move east 1 unit and get blocked by the obstacle at (2, 4), robot is at (1, 4).
-4. Turn left.
-5. Move north 4 units to (1, 8).
-The furthest point away from the origin is (1, 8), which is 1<sup>2</sup> + 8<sup>2</sup> = 65 units away.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= commands.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>commands[i]</code> is one of the values in the list <code>[-2,-1,1,2,3,4,5,6,7,8,9]</code>.</li>
-	<li><code>0 &lt;= obstacles.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>-3 * 10<sup>4</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 3 * 10<sup>4</sup></code></li>
-	<li>The answer is guaranteed to be less than <code>2<sup>31</sup></code>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
diff --git a/problems/walking-robot-simulation/walking_robot_simulation.go b/problems/walking-robot-simulation/walking_robot_simulation.go
deleted file mode 100644
index c642a1015..000000000
--- a/problems/walking-robot-simulation/walking_robot_simulation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem874
diff --git a/problems/walking-robot-simulation/walking_robot_simulation_test.go b/problems/walking-robot-simulation/walking_robot_simulation_test.go
deleted file mode 100644
index c642a1015..000000000
--- a/problems/walking-robot-simulation/walking_robot_simulation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem874
diff --git a/problems/walls-and-gates/README.md b/problems/walls-and-gates/README.md
deleted file mode 100644
index 520654f7a..000000000
--- a/problems/walls-and-gates/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../inorder-successor-in-bst "Inorder Successor in BST")
-　　　　　　　　　　　　　　　　
-[Next >](../find-the-duplicate-number "Find the Duplicate Number")
-
-## [286. Walls and Gates (Medium)](https://leetcode.com/problems/walls-and-gates "墙与门")
-
-<p>You are given a <i>m x n</i> 2D grid initialized with these three possible values.</p>
-
-<ol>
-	<li><code>-1</code> - A wall or an obstacle.</li>
-	<li><code>0</code> - A gate.</li>
-	<li><code>INF</code> - Infinity means an empty room. We use the value <code>2<sup>31</sup> - 1 = 2147483647</code> to represent <code>INF</code> as you may assume that the distance to a gate is less than <code>2147483647</code>.</li>
-</ol>
-
-<p>Fill each empty room with the distance to its <i>nearest</i> gate. If it is impossible to reach a gate, it should be filled with <code>INF</code>.</p>
-
-<p><strong>Example:&nbsp;</strong></p>
-
-<p>Given the 2D grid:</p>
-
-<pre>
-INF  -1  0  INF
-INF INF INF  -1
-INF  -1 INF  -1
-  0  -1 INF INF
-</pre>
-
-<p>After running your function, the 2D grid should be:</p>
-
-<pre>
-  3  -1   0   1
-  2   2   1  -1
-  1  -1   2  -1
-  0  -1   3   4
-</pre>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Surrounded Regions](../surrounded-regions) (Medium)
-  1. [Number of Islands](../number-of-islands) (Medium)
-  1. [Shortest Distance from All Buildings](../shortest-distance-from-all-buildings) (Hard)
-  1. [Robot Room Cleaner](../robot-room-cleaner) (Hard)
-  1. [Rotting Oranges](../rotting-oranges) (Medium)
diff --git a/problems/walls-and-gates/walls_and_gates.go b/problems/walls-and-gates/walls_and_gates.go
deleted file mode 100644
index 351d5d720..000000000
--- a/problems/walls-and-gates/walls_and_gates.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem286
diff --git a/problems/walls-and-gates/walls_and_gates_test.go b/problems/walls-and-gates/walls_and_gates_test.go
deleted file mode 100644
index 351d5d720..000000000
--- a/problems/walls-and-gates/walls_and_gates_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem286
diff --git a/problems/warehouse-manager/README.md b/problems/warehouse-manager/README.md
deleted file mode 100644
index 1bd5e33f8..000000000
--- a/problems/warehouse-manager/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../dot-product-of-two-sparse-vectors "Dot Product of Two Sparse Vectors")
-　　　　　　　　　　　　　　　　
-[Next >](../matrix-diagonal-sum "Matrix Diagonal Sum")
-
-## [1571. Warehouse Manager (Easy)](https://leetcode.com/problems/warehouse-manager "仓库经理")
-
-
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/warehouse-manager/mysql_schemas.sql b/problems/warehouse-manager/mysql_schemas.sql
deleted file mode 100644
index 6f0007cf0..000000000
--- a/problems/warehouse-manager/mysql_schemas.sql
+++ /dev/null
@@ -1,15 +0,0 @@
-Create table If Not Exists Warehouse (name varchar(50), product_id int, units int)
-;
-Create table If Not Exists Products (product_id int, product_name varchar(50), Width int,Length int,Height int);
-Truncate table Warehouse;
-insert into Warehouse (name, product_id, units) values ('LCHouse1', '1', '1');
-insert into Warehouse (name, product_id, units) values ('LCHouse1', '2', '10');
-insert into Warehouse (name, product_id, units) values ('LCHouse1', '3', '5');
-insert into Warehouse (name, product_id, units) values ('LCHouse2', '1', '2');
-insert into Warehouse (name, product_id, units) values ('LCHouse2', '2', '2');
-insert into Warehouse (name, product_id, units) values ('LCHouse3', '4', '1');
-Truncate table Products;
-insert into Products (product_id, product_name, Width, Length, Height) values ('1', 'LC-TV', '5', '50', '40');
-insert into Products (product_id, product_name, Width, Length, Height) values ('2', 'LC-KeyChain', '5', '5', '5');
-insert into Products (product_id, product_name, Width, Length, Height) values ('3', 'LC-Phone', '2', '10', '10');
-insert into Products (product_id, product_name, Width, Length, Height) values ('4', 'LC-T-Shirt', '4', '10', '20');
diff --git a/problems/water-and-jug-problem/README.md b/problems/water-and-jug-problem/README.md
deleted file mode 100644
index c9fd6768f..000000000
--- a/problems/water-and-jug-problem/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../nested-list-weight-sum-ii "Nested List Weight Sum II")
-　　　　　　　　　　　　　　　　
-[Next >](../find-leaves-of-binary-tree "Find Leaves of Binary Tree")
-
-## [365. Water and Jug Problem (Medium)](https://leetcode.com/problems/water-and-jug-problem "水壶问题")
-
-<p>You are given two jugs with capacities <code>jug1Capacity</code> and <code>jug2Capacity</code> liters. There is an infinite amount of water supply available. Determine whether it is possible to measure exactly <code>targetCapacity</code> liters using these two jugs.</p>
-
-<p>If <code>targetCapacity</code> liters of water are measurable, you must have <code>targetCapacity</code> liters of water contained <strong>within one or both buckets</strong> by the end.</p>
-
-<p>Operations allowed:</p>
-
-<ul>
-	<li>Fill any of the jugs with water.</li>
-	<li>Empty any of the jugs.</li>
-	<li>Pour water from one jug into another till the other jug is completely full, or the first jug itself is empty.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> jug1Capacity = 3, jug2Capacity = 5, targetCapacity = 4
-<strong>Output:</strong> true
-<strong>Explanation:</strong> The famous <a href="https://www.youtube.com/watch?v=BVtQNK_ZUJg&amp;ab_channel=notnek01" target="_blank">Die Hard</a> example 
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> jug1Capacity = 2, jug2Capacity = 6, targetCapacity = 5
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> jug1Capacity = 1, jug2Capacity = 2, targetCapacity = 3
-<strong>Output:</strong> true
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= jug1Capacity, jug2Capacity, targetCapacity &lt;= 10<sup>6</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Math](../../tag/math/README.md)]
diff --git a/problems/water-and-jug-problem/water_and_jug_problem.go b/problems/water-and-jug-problem/water_and_jug_problem.go
deleted file mode 100644
index 860a790a1..000000000
--- a/problems/water-and-jug-problem/water_and_jug_problem.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem365
diff --git a/problems/water-and-jug-problem/water_and_jug_problem_test.go b/problems/water-and-jug-problem/water_and_jug_problem_test.go
deleted file mode 100644
index 860a790a1..000000000
--- a/problems/water-and-jug-problem/water_and_jug_problem_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem365
diff --git a/problems/water-bottles/README.md b/problems/water-bottles/README.md
deleted file mode 100644
index b299bdd88..000000000
--- a/problems/water-bottles/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-users-with-valid-e-mails "Find Users With Valid E-Mails")
-　　　　　　　　　　　　　　　　
-[Next >](../number-of-nodes-in-the-sub-tree-with-the-same-label "Number of Nodes in the Sub-Tree With the Same Label")
-
-## [1518. Water Bottles (Easy)](https://leetcode.com/problems/water-bottles "换酒问题")
-
-<p>There are <code>numBottles</code> water bottles that are initially full of water. You can exchange <code>numExchange</code> empty water bottles from the market with one full water bottle.</p>
-
-<p>The operation of drinking a full water bottle turns it into an empty bottle.</p>
-
-<p>Given the two integers <code>numBottles</code> and <code>numExchange</code>, return <em>the <strong>maximum</strong> number of water bottles you can drink</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/01/sample_1_1875.png" style="width: 500px; height: 245px;" />
-<pre>
-<strong>Input:</strong> numBottles = 9, numExchange = 3
-<strong>Output:</strong> 13
-<strong>Explanation:</strong> You can exchange 3 empty bottles to get 1 full water bottle.
-Number of water bottles you can drink: 9 + 3 + 1 = 13.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/07/01/sample_2_1875.png" style="width: 500px; height: 183px;" />
-<pre>
-<strong>Input:</strong> numBottles = 15, numExchange = 4
-<strong>Output:</strong> 19
-<strong>Explanation:</strong> You can exchange 4 empty bottles to get 1 full water bottle. 
-Number of water bottles you can drink: 15 + 3 + 1 = 19.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= numBottles &lt;= 100</code></li>
-	<li><code>2 &lt;= numExchange &lt;= 100</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process until there are not enough empty bottles for even one full bottle of water.
-</details>
diff --git a/problems/watering-plants-ii/README.md b/problems/watering-plants-ii/README.md
deleted file mode 100644
index 1d68c1646..000000000
--- a/problems/watering-plants-ii/README.md
+++ /dev/null
@@ -1,94 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sum-of-subarray-ranges "Sum of Subarray Ranges")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-fruits-harvested-after-at-most-k-steps "Maximum Fruits Harvested After at Most K Steps")
-
-## [2105. Watering Plants II (Medium)](https://leetcode.com/problems/watering-plants-ii "给植物浇水 II")
-
-<p>Alice and Bob want to water <code>n</code> plants in their garden. The plants are arranged in a row and are labeled from <code>0</code> to <code>n - 1</code> from left to right where the <code>i<sup>th</sup></code> plant is located at <code>x = i</code>.</p>
-
-<p>Each plant needs a specific amount of water. Alice and Bob have a watering can each, <strong>initially full</strong>. They water the plants in the following way:</p>
-
-<ul>
-	<li>Alice waters the plants in order from <strong>left to right</strong>, starting from the <code>0<sup>th</sup></code> plant. Bob waters the plants in order from <strong>right to left</strong>, starting from the <code>(n - 1)<sup>th</sup></code> plant. They begin watering the plants <strong>simultaneously</strong>.</li>
-	<li>It takes the same amount of time to water each plant regardless of how much water it needs.</li>
-	<li>Alice/Bob <strong>must</strong> water the plant if they have enough in their can to <strong>fully</strong> water it. Otherwise, they <strong>first</strong> refill their can (instantaneously) then water the plant.</li>
-	<li>In case both Alice and Bob reach the same plant, the one with <strong>more</strong> water currently in his/her watering can should water this plant. If they have the same amount of water, then Alice should water this plant.</li>
-</ul>
-
-<p>Given a <strong>0-indexed</strong> integer array <code>plants</code> of <code>n</code> integers, where <code>plants[i]</code> is the amount of water the <code>i<sup>th</sup></code> plant needs, and two integers <code>capacityA</code> and <code>capacityB</code> representing the capacities of Alice&#39;s and Bob&#39;s watering cans respectively, return <em>the <strong>number of times</strong> they have to refill to water all the plants</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> plants = [2,2,3,3], capacityA = 5, capacityB = 5
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-- Initially, Alice and Bob have 5 units of water each in their watering cans.
-- Alice waters plant 0, Bob waters plant 3.
-- Alice and Bob now have 3 units and 2 units of water respectively.
-- Alice has enough water for plant 1, so she waters it. Bob does not have enough water for plant 2, so he refills his can then waters it.
-So, the total number of times they have to refill to water all the plants is 0 + 0 + 1 + 0 = 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> plants = [2,2,3,3], capacityA = 3, capacityB = 4
-<strong>Output:</strong> 2
-<strong>Explanation:</strong>
-- Initially, Alice and Bob have 3 units and 4 units of water in their watering cans respectively.
-- Alice waters plant 0, Bob waters plant 3.
-- Alice and Bob now have 1 unit of water each, and need to water plants 1 and 2 respectively.
-- Since neither of them have enough water for their current plants, they refill their cans and then water the plants.
-So, the total number of times they have to refill to water all the plants is 0 + 1 + 1 + 0 = 2.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> plants = [5], capacityA = 10, capacityB = 8
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>
-- There is only one plant.
-- Alice&#39;s watering can has 10 units of water, whereas Bob&#39;s can has 8 units. Since Alice has more water in her can, she waters this plant.
-So, the total number of times they have to refill is 0.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == plants.length</code></li>
-	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= plants[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>max(plants[i]) &lt;= capacityA, capacityB &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try "simulating" the process.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Since watering each plant takes the same amount of time, where will Alice and Bob meet if they start watering the plants simultaneously? How can you use this to optimize your solution?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What will you do when both Alice and Bob have to water the same plant?
-</details>
diff --git a/problems/watering-plants/README.md b/problems/watering-plants/README.md
deleted file mode 100644
index a130195d4..000000000
--- a/problems/watering-plants/README.md
+++ /dev/null
@@ -1,88 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../two-furthest-houses-with-different-colors "Two Furthest Houses With Different Colors")
-　　　　　　　　　　　　　　　　
-[Next >](../range-frequency-queries "Range Frequency Queries")
-
-## [2079. Watering Plants (Medium)](https://leetcode.com/problems/watering-plants "给植物浇水")
-
-<p>You want to water <code>n</code> plants in your garden with a watering can. The plants are arranged in a row and are labeled from <code>0</code> to <code>n - 1</code> from left to right where the <code>i<sup>th</sup></code> plant is located at <code>x = i</code>. There is a river at <code>x = -1</code> that you can refill your watering can at.</p>
-
-<p>Each plant needs a specific amount of water. You will water the plants in the following way:</p>
-
-<ul>
-	<li>Water the plants in order from left to right.</li>
-	<li>After watering the current plant, if you do not have enough water to <strong>completely</strong> water the next plant, return to the river to fully refill the watering can.</li>
-	<li>You <strong>cannot</strong> refill the watering can early.</li>
-</ul>
-
-<p>You are initially at the river (i.e., <code>x = -1</code>). It takes <strong>one step</strong> to move <strong>one unit</strong> on the x-axis.</p>
-
-<p>Given a <strong>0-indexed</strong> integer array <code>plants</code> of <code>n</code> integers, where <code>plants[i]</code> is the amount of water the <code>i<sup>th</sup></code> plant needs, and an integer <code>capacity</code> representing the watering can capacity, return <em>the <strong>number of steps</strong> needed to water all the plants</em>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> plants = [2,2,3,3], capacity = 5
-<strong>Output:</strong> 14
-<strong>Explanation:</strong> Start at the river with a full watering can:
-- Walk to plant 0 (1 step) and water it. Watering can has 3 units of water.
-- Walk to plant 1 (1 step) and water it. Watering can has 1 unit of water.
-- Since you cannot completely water plant 2, walk back to the river to refill (2 steps).
-- Walk to plant 2 (3 steps) and water it. Watering can has 2 units of water.
-- Since you cannot completely water plant 3, walk back to the river to refill (3 steps).
-- Walk to plant 3 (4 steps) and water it.
-Steps needed = 1 + 1 + 2 + 3 + 3 + 4 = 14.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> plants = [1,1,1,4,2,3], capacity = 4
-<strong>Output:</strong> 30
-<strong>Explanation:</strong> Start at the river with a full watering can:
-- Water plants 0, 1, and 2 (3 steps). Return to river (3 steps).
-- Water plant 3 (4 steps). Return to river (4 steps).
-- Water plant 4 (5 steps). Return to river (5 steps).
-- Water plant 5 (6 steps).
-Steps needed = 3 + 3 + 4 + 4 + 5 + 5 + 6 = 30.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> plants = [7,7,7,7,7,7,7], capacity = 8
-<strong>Output:</strong> 49
-<strong>Explanation:</strong> You have to refill before watering each plant.
-Steps needed = 1 + 1 + 2 + 2 + 3 + 3 + 4 + 4 + 5 + 5 + 6 + 6 + 7 = 49.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == plants.length</code></li>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>1 &lt;= plants[i] &lt;= 10<sup>6</sup></code></li>
-	<li><code>max(plants[i]) &lt;= capacity &lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Return to refill the container once you meet a plant that needs more water than you have.
-</details>
diff --git a/problems/ways-to-make-a-fair-array/README.md b/problems/ways-to-make-a-fair-array/README.md
deleted file mode 100644
index b09a128d7..000000000
--- a/problems/ways-to-make-a-fair-array/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../smallest-string-with-a-given-numeric-value "Smallest String With A Given Numeric Value")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-initial-energy-to-finish-tasks "Minimum Initial Energy to Finish Tasks")
-
-## [1664. Ways to Make a Fair Array (Medium)](https://leetcode.com/problems/ways-to-make-a-fair-array "生成平衡数组的方案数")
-
-<p>You are given an integer array&nbsp;<code>nums</code>. You can choose <strong>exactly one</strong> index (<strong>0-indexed</strong>) and remove the element. Notice that the index of the elements may change after the removal.</p>
-
-<p>For example, if <code>nums = [6,1,7,4,1]</code>:</p>
-
-<ul>
-	<li>Choosing to remove index <code>1</code> results in <code>nums = [6,7,4,1]</code>.</li>
-	<li>Choosing to remove index <code>2</code> results in <code>nums = [6,1,4,1]</code>.</li>
-	<li>Choosing to remove index <code>4</code> results in <code>nums = [6,1,7,4]</code>.</li>
-</ul>
-
-<p>An array is <strong>fair</strong> if the sum of the odd-indexed values equals the sum of the even-indexed values.</p>
-
-<p>Return the <em><strong>number</strong> of indices that you could choose such that after the removal, </em><code>nums</code><em> </em><em>is <strong>fair</strong>. </em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [2,1,6,4]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong>
-Remove index 0: [1,6,4] -&gt; Even sum: 1 + 4 = 5. Odd sum: 6. Not fair.
-Remove index 1: [2,6,4] -&gt; Even sum: 2 + 4 = 6. Odd sum: 6. Fair.
-Remove index 2: [2,1,4] -&gt; Even sum: 2 + 4 = 6. Odd sum: 1. Not fair.
-Remove index 3: [2,1,6] -&gt; Even sum: 2 + 6 = 8. Odd sum: 1. Not fair.
-There is 1 index that you can remove to make nums fair.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong>&nbsp;You can remove any index and the remaining array is fair.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong>&nbsp;You cannot make a fair array after removing any index.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-The parity of the indices after the removed element changes.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Calculate prefix sums for even and odd indices separately to calculate for each index in O(1).
-</details>
diff --git a/problems/ways-to-split-array-into-three-subarrays/README.md b/problems/ways-to-split-array-into-three-subarrays/README.md
deleted file mode 100644
index f9621b2da..000000000
--- a/problems/ways-to-split-array-into-three-subarrays/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../count-good-meals "Count Good Meals")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-operations-to-make-a-subsequence "Minimum Operations to Make a Subsequence")
-
-## [1712. Ways to Split Array Into Three Subarrays (Medium)](https://leetcode.com/problems/ways-to-split-array-into-three-subarrays "将数组分成三个子数组的方案数")
-
-<p>A split of an integer array is <strong>good</strong> if:</p>
-
-<ul>
-	<li>The array is split into three <strong>non-empty</strong> contiguous subarrays - named <code>left</code>, <code>mid</code>, <code>right</code> respectively from left to right.</li>
-	<li>The sum of the elements in <code>left</code> is less than or equal to the sum of the elements in <code>mid</code>, and the sum of the elements in <code>mid</code> is less than or equal to the sum of the elements in <code>right</code>.</li>
-</ul>
-
-<p>Given <code>nums</code>, an array of <strong>non-negative</strong> integers, return <em>the number of <strong>good</strong> ways to split</em> <code>nums</code>. As the number may be too large, return it <strong>modulo</strong> <code>10<sup>9 </sup>+ 7</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,1,1]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> The only good way to split nums is [1] [1] [1].</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,2,2,5,0]
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> There are three good ways of splitting nums:
-[1] [2] [2,2,5,0]
-[1] [2,2] [2,5,0]
-[1,2] [2,2] [5,0]
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [3,2,1]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> There is no good way to split nums.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>3 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Two Pointers](../../tag/two-pointers/README.md)]
-  [[Binary Search](../../tag/binary-search/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Similar Questions
-  1. [Number of Ways to Divide a Long Corridor](../number-of-ways-to-divide-a-long-corridor) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Create a prefix array to efficiently find the sum of subarrays.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-As we are dividing the array into three subarrays, there are two "walls". Iterate over the right wall positions and find where the left wall could be for each right wall position.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Use binary search to find the left-most position and right-most position the left wall could be.
-</details>
diff --git a/problems/weather-type-in-each-country/README.md b/problems/weather-type-in-each-country/README.md
deleted file mode 100644
index a58e2ea24..000000000
--- a/problems/weather-type-in-each-country/README.md
+++ /dev/null
@@ -1,99 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../shortest-path-in-a-grid-with-obstacles-elimination "Shortest Path in a Grid with Obstacles Elimination")
-　　　　　　　　　　　　　　　　
-[Next >](../find-numbers-with-even-number-of-digits "Find Numbers with Even Number of Digits")
-
-## [1294. Weather Type in Each Country (Easy)](https://leetcode.com/problems/weather-type-in-each-country "不同国家的天气类型")
-
-<p>Table: <code>Countries</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| country_id    | int     |
-| country_name  | varchar |
-+---------------+---------+
-country_id is the primary key for this table.
-Each row of this table contains the ID and the name of one country.
-</pre>
- 
-<p>Table: <code>Weather</code></p>
-<pre>
-+---------------+---------+
-| Column Name   | Type    |
-+---------------+---------+
-| country_id    | int     |
-| weather_state | varchar |
-| day           | date    |
-+---------------+---------+
-(country_id, day) is the primary key for this table.
-Each row of this table indicates the weather state in a country for one day.
-</pre>
- 
-Write an SQL query to find the type of weather in each country for November 2019.
-
-The type of weather is Cold if the average weather_state is less than or equal 15, Hot if the average weather_state is greater than or equal 25 and Warm otherwise.
-
-Return result table in any order.
-
-The query result format is in the following example:
-<pre>
-Countries table:
-+------------+--------------+
-| country_id | country_name |
-+------------+--------------+
-| 2          | USA          |
-| 3          | Australia    |
-| 7          | Peru         |
-| 5          | China        |
-| 8          | Morocco      |
-| 9          | Spain        |
-+------------+--------------+
-Weather table:
-+------------+---------------+------------+
-| country_id | weather_state | day        |
-+------------+---------------+------------+
-| 2          | 15            | 2019-11-01 |
-| 2          | 12            | 2019-10-28 |
-| 2          | 12            | 2019-10-27 |
-| 3          | -2            | 2019-11-10 |
-| 3          | 0             | 2019-11-11 |
-| 3          | 3             | 2019-11-12 |
-| 5          | 16            | 2019-11-07 |
-| 5          | 18            | 2019-11-09 |
-| 5          | 21            | 2019-11-23 |
-| 7          | 25            | 2019-11-28 |
-| 7          | 22            | 2019-12-01 |
-| 7          | 20            | 2019-12-02 |
-| 8          | 25            | 2019-11-05 |
-| 8          | 27            | 2019-11-15 |
-| 8          | 31            | 2019-11-25 |
-| 9          | 7             | 2019-10-23 |
-| 9          | 3             | 2019-12-23 |
-+------------+---------------+------------+
-Result table:
-+--------------+--------------+
-| country_name | weather_type |
-+--------------+--------------+
-| USA          | Cold         |
-| Austraila    | Cold         |
-| Peru         | Hot          |
-| China        | Warm         |
-| Morocco      | Hot          |
-+--------------+--------------+
-Average weather_state in USA in November is (15) / 1 = 15 so weather type is Cold.
-Average weather_state in Austraila in November is (-2 + 0 + 3) / 3 = 0.333 so weather type is Cold.
-Average weather_state in Peru in November is (25) / 1 = 25 so weather type is Hot.
-Average weather_state in China in November is (16 + 18 + 21) / 3 = 18.333 so weather type is Warm.
-Average weather_state in Morocco in November is (25 + 27 + 31) / 3 = 27.667 so weather type is Hot.
-We know nothing about average weather_state in Spain in November so we don't include it in the result table. 
-</pre>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/weather-type-in-each-country/mysql_schemas.sql b/problems/weather-type-in-each-country/mysql_schemas.sql
deleted file mode 100644
index 047159d79..000000000
--- a/problems/weather-type-in-each-country/mysql_schemas.sql
+++ /dev/null
@@ -1,27 +0,0 @@
-Create table If Not Exists Countries (country_id int, country_name varchar(20));
-Create table If Not Exists Weather (country_id int, weather_state int, day date);
-Truncate table Countries;
-insert into Countries (country_id, country_name) values ('2', 'USA');
-insert into Countries (country_id, country_name) values ('3', 'Australia');
-insert into Countries (country_id, country_name) values ('7', 'Peru');
-insert into Countries (country_id, country_name) values ('5', 'China');
-insert into Countries (country_id, country_name) values ('8', 'Morocco');
-insert into Countries (country_id, country_name) values ('9', 'Spain');
-Truncate table Weather;
-insert into Weather (country_id, weather_state, day) values ('2', '15', '2019-11-01');
-insert into Weather (country_id, weather_state, day) values ('2', '12', '2019-10-28');
-insert into Weather (country_id, weather_state, day) values ('2', '12', '2019-10-27');
-insert into Weather (country_id, weather_state, day) values ('3', '-2', '2019-11-10');
-insert into Weather (country_id, weather_state, day) values ('3', '0', '2019-11-11');
-insert into Weather (country_id, weather_state, day) values ('3', '3', '2019-11-12');
-insert into Weather (country_id, weather_state, day) values ('5', '16', '2019-11-07');
-insert into Weather (country_id, weather_state, day) values ('5', '18', '2019-11-09');
-insert into Weather (country_id, weather_state, day) values ('5', '21', '2019-11-23');
-insert into Weather (country_id, weather_state, day) values ('7', '25', '2019-11-28');
-insert into Weather (country_id, weather_state, day) values ('7', '22', '2019-12-01');
-insert into Weather (country_id, weather_state, day) values ('7', '20', '2019-12-02');
-insert into Weather (country_id, weather_state, day) values ('8', '25', '2019-11-05');
-insert into Weather (country_id, weather_state, day) values ('8', '27', '2019-11-15');
-insert into Weather (country_id, weather_state, day) values ('8', '31', '2019-11-25');
-insert into Weather (country_id, weather_state, day) values ('9', '7', '2019-10-23');
-insert into Weather (country_id, weather_state, day) values ('9', '3', '2019-12-23');
diff --git a/problems/weather-type-in-each-country/weather_type_in_each_country.sql b/problems/weather-type-in-each-country/weather_type_in_each_country.sql
deleted file mode 100644
index 01fa68ac9..000000000
--- a/problems/weather-type-in-each-country/weather_type_in_each_country.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT country_name,
-       CASE
-           WHEN avg(weather_state) <= 15 THEN "Cold"
-           WHEN avg(weather_state) >= 25 THEN "Hot"
-           ELSE "Warm" END AS weather_type
-FROM Countries
-         INNER JOIN Weather ON Countries.country_id = Weather.country_id
-WHERE LEFT(DAY, 7) = '2019-11'
-GROUP BY country_name
diff --git a/problems/web-crawler-multithreaded/README.md b/problems/web-crawler-multithreaded/README.md
deleted file mode 100644
index 40b986e48..000000000
--- a/problems/web-crawler-multithreaded/README.md
+++ /dev/null
@@ -1,114 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-comments-per-post "Number of Comments per Post")
-　　　　　　　　　　　　　　　　
-[Next >](../array-transformation "Array Transformation")
-
-## [1242. Web Crawler Multithreaded (Medium)](https://leetcode.com/problems/web-crawler-multithreaded "多线程网页爬虫")
-
-<p>Given a url <code>startUrl</code> and an interface <code>HtmlParser</code>, implement <strong>a Multi-threaded web&nbsp;crawler</strong> to crawl all links that are under the&nbsp;<strong>same hostname</strong> as&nbsp;<code>startUrl</code>.&nbsp;</p>
-
-<p>Return&nbsp;all urls obtained by your web crawler in <strong>any</strong> order.</p>
-
-<p>Your crawler should:</p>
-
-<ul>
-	<li>Start from the page: <code>startUrl</code></li>
-	<li>Call <code>HtmlParser.getUrls(url)</code> to get all urls from a webpage of given url.</li>
-	<li>Do not crawl the same link twice.</li>
-	<li>Explore only the links that are under the <strong>same hostname</strong> as <code>startUrl</code>.</li>
-</ul>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/08/13/urlhostname.png" style="width: 600px; height: 164px;" /></p>
-
-<p>As shown in the example url above, the hostname is <code>example.org</code>. For simplicity sake, you may assume all&nbsp;urls use <strong>http protocol</strong> without any&nbsp;<strong>port</strong> specified. For example, the urls&nbsp;<code>http://leetcode.com/problems</code> and&nbsp;<code>http://leetcode.com/contest</code> are under the same hostname, while urls <code>http://example.org/test</code> and <code>http://example.com/abc</code> are not under the same hostname.</p>
-
-<p>The <code>HtmlParser</code> interface is defined as such:&nbsp;</p>
-
-<pre>
-interface HtmlParser {
-  // Return a list of all urls from a webpage of given <em>url</em>.
-  // This is a blocking call, that means it will do HTTP request and return when this request is finished.
-  public List&lt;String&gt; getUrls(String url);
-}</pre>
-
-<p>Note that&nbsp;<code>getUrls(String url)</code>&nbsp;simulates performing a&nbsp;HTTP request. You can treat it as a blocking function call which waits for a&nbsp;HTTP request to finish. It is guaranteed that&nbsp;<code>getUrls(String url)</code> will return the urls within <strong>15ms.&nbsp;</strong> Single-threaded solutions will exceed the time limit so, can your multi-threaded web crawler do better?</p>
-
-<p>Below&nbsp;are two examples explaining the functionality of the problem, for custom testing purposes you&#39;ll have three&nbsp;variables&nbsp;<code data-stringify-type="code">urls</code>,&nbsp;<code data-stringify-type="code">edges</code>&nbsp;and&nbsp;<code data-stringify-type="code">startUrl</code>. Notice that you will only have access to&nbsp;<code data-stringify-type="code">startUrl</code>&nbsp;in your code, while&nbsp;<code data-stringify-type="code">urls</code>&nbsp;and&nbsp;<code data-stringify-type="code">edges</code>&nbsp;are not directly accessible to you in code.</p>
-
-<p>&nbsp;</p>
-
-<p><strong>Follow up:</strong></p>
-
-<ol>
-	<li>Assume we have 10,000 nodes and 1 billion URLs to crawl.&nbsp;We will deploy the same software onto each node.&nbsp;The software can know about all the nodes. We have to minimize communication between machines and make sure each node does equal amount of work. How would your web crawler design change?</li>
-	<li>What if one node fails or does not work?</li>
-	<li>How do you know when the crawler is done?</li>
-</ol>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/23/sample_2_1497.png" style="width: 610px; height: 300px;" /></p>
-
-<pre>
-<strong>Input:
-</strong>urls = [
-&nbsp; &quot;http://news.yahoo.com&quot;,
-&nbsp; &quot;http://news.yahoo.com/news&quot;,
-&nbsp; &quot;http://news.yahoo.com/news/topics/&quot;,
-&nbsp; &quot;http://news.google.com&quot;,
-&nbsp; &quot;http://news.yahoo.com/us&quot;
-]
-edges = [[2,0],[2,1],[3,2],[3,1],[0,4]]
-startUrl = &quot;http://news.yahoo.com/news/topics/&quot;
-<strong>Output:</strong> [
-&nbsp; &quot;http://news.yahoo.com&quot;,
-&nbsp; &quot;http://news.yahoo.com/news&quot;,
-&nbsp; &quot;http://news.yahoo.com/news/topics/&quot;,
-&nbsp; &quot;http://news.yahoo.com/us&quot;
-]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/10/23/sample_3_1497.png" style="width: 540px; height: 270px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> 
-urls = [
-&nbsp; &quot;http://news.yahoo.com&quot;,
-&nbsp; &quot;http://news.yahoo.com/news&quot;,
-&nbsp; &quot;http://news.yahoo.com/news/topics/&quot;,
-&nbsp; &quot;http://news.google.com&quot;
-]
-edges = [[0,2],[2,1],[3,2],[3,1],[3,0]]
-startUrl = &quot;http://news.google.com&quot;
-<strong>Output:</strong> [&quot;http://news.google.com&quot;]
-<strong>Explanation: </strong>The startUrl links to all other pages that do not share the same hostname.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= urls.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= urls[i].length &lt;= 300</code></li>
-	<li><code>startUrl</code>&nbsp;is one of the <code>urls</code>.</li>
-	<li>Hostname label must be from 1 to 63 characters long, including the dots, may contain only the ASCII letters from &#39;a&#39; to&nbsp;&#39;z&#39;, digits from &#39;0&#39; to &#39;9&#39; and the&nbsp;hyphen-minus&nbsp;character (&#39;-&#39;).</li>
-	<li>The hostname may not start or end with&nbsp;the hyphen-minus character (&#39;-&#39;).&nbsp;</li>
-	<li>See:&nbsp;&nbsp;<a href="https://en.wikipedia.org/wiki/Hostname#Restrictions_on_valid_hostnames">https://en.wikipedia.org/wiki/Hostname#Restrictions_on_valid_hostnames</a></li>
-	<li>You may assume there&#39;re&nbsp;no duplicates in url library.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Concurrency](../../tag/concurrency/README.md)]
-
-### Similar Questions
-  1. [Web Crawler](../web-crawler) (Medium)
diff --git a/problems/web-crawler/README.md b/problems/web-crawler/README.md
deleted file mode 100644
index e6bd65041..000000000
--- a/problems/web-crawler/README.md
+++ /dev/null
@@ -1,108 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-profit-in-job-scheduling "Maximum Profit in Job Scheduling")
-　　　　　　　　　　　　　　　　
-[Next >](../find-positive-integer-solution-for-a-given-equation "Find Positive Integer Solution for a Given Equation")
-
-## [1236. Web Crawler (Medium)](https://leetcode.com/problems/web-crawler "网络爬虫")
-
-<p>Given a url <code>startUrl</code> and an interface <code>HtmlParser</code>, implement a web&nbsp;crawler to crawl all links that are under the&nbsp;<strong>same hostname</strong> as&nbsp;<code>startUrl</code>.&nbsp;</p>
-
-<p>Return&nbsp;all urls obtained by your web crawler in <strong>any</strong> order.</p>
-
-<p>Your crawler should:</p>
-
-<ul>
-	<li>Start from the page: <code>startUrl</code></li>
-	<li>Call <code>HtmlParser.getUrls(url)</code> to get all urls from a webpage of given url.</li>
-	<li>Do not crawl the same link twice.</li>
-	<li>Explore only the links that are under the <strong>same hostname</strong> as <code>startUrl</code>.</li>
-</ul>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/08/13/urlhostname.png" style="width: 600px; height: 164px;" /></p>
-
-<p>As shown in the example url above, the hostname is <code>example.org</code>. For simplicity sake, you may assume all&nbsp;urls use <strong>http protocol</strong> without any&nbsp;<strong>port</strong> specified. For example, the urls&nbsp;<code>http://leetcode.com/problems</code> and&nbsp;<code>http://leetcode.com/contest</code> are under the same hostname, while urls <code>http://example.org/test</code> and <code>http://example.com/abc</code> are not under the same hostname.</p>
-
-<p>The <code>HtmlParser</code> interface is defined as such:&nbsp;</p>
-
-<pre>
-interface HtmlParser {
-  // Return a list of all urls from a webpage of given <em>url</em>.
-  public List&lt;String&gt; getUrls(String url);
-}</pre>
-
-<p>Below&nbsp;are two examples explaining the functionality of the problem, for custom testing purposes you&#39;ll have three&nbsp;variables&nbsp;<code data-stringify-type="code">urls</code>,&nbsp;<code data-stringify-type="code">edges</code>&nbsp;and&nbsp;<code data-stringify-type="code">startUrl</code>. Notice that you will only have access to&nbsp;<code data-stringify-type="code">startUrl</code>&nbsp;in your code, while&nbsp;<code data-stringify-type="code">urls</code>&nbsp;and&nbsp;<code data-stringify-type="code">edges</code>&nbsp;are not directly accessible to you in code.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/23/sample_2_1497.png" style="width: 610px; height: 300px;" /></p>
-
-<pre>
-<strong>Input:
-</strong>urls = [
-&nbsp; &quot;http://news.yahoo.com&quot;,
-&nbsp; &quot;http://news.yahoo.com/news&quot;,
-&nbsp; &quot;http://news.yahoo.com/news/topics/&quot;,
-&nbsp; &quot;http://news.google.com&quot;,
-&nbsp; &quot;http://news.yahoo.com/us&quot;
-]
-edges = [[2,0],[2,1],[3,2],[3,1],[0,4]]
-startUrl = &quot;http://news.yahoo.com/news/topics/&quot;
-<strong>Output:</strong> [
-&nbsp; &quot;http://news.yahoo.com&quot;,
-&nbsp; &quot;http://news.yahoo.com/news&quot;,
-&nbsp; &quot;http://news.yahoo.com/news/topics/&quot;,
-&nbsp; &quot;http://news.yahoo.com/us&quot;
-]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/10/23/sample_3_1497.png" style="width: 540px; height: 270px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> 
-urls = [
-&nbsp; &quot;http://news.yahoo.com&quot;,
-&nbsp; &quot;http://news.yahoo.com/news&quot;,
-&nbsp; &quot;http://news.yahoo.com/news/topics/&quot;,
-&nbsp; &quot;http://news.google.com&quot;
-]
-edges = [[0,2],[2,1],[3,2],[3,1],[3,0]]
-startUrl = &quot;http://news.google.com&quot;
-<strong>Output:</strong> [&quot;http://news.google.com&quot;]
-<strong>Explanation: </strong>The startUrl links to all other pages that do not share the same hostname.</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= urls.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= urls[i].length &lt;= 300</code></li>
-	<li><code>startUrl</code>&nbsp;is one of the <code>urls</code>.</li>
-	<li>Hostname label must be from 1 to 63 characters long, including the dots, may contain only the ASCII letters from &#39;a&#39; to&nbsp;&#39;z&#39;, digits&nbsp; from &#39;0&#39; to &#39;9&#39; and the&nbsp;hyphen-minus&nbsp;character (&#39;-&#39;).</li>
-	<li>The hostname may not start or end with&nbsp;the hyphen-minus character (&#39;-&#39;).&nbsp;</li>
-	<li>See:&nbsp;&nbsp;<a href="https://en.wikipedia.org/wiki/Hostname#Restrictions_on_valid_hostnames">https://en.wikipedia.org/wiki/Hostname#Restrictions_on_valid_hostnames</a></li>
-	<li>You may assume there&#39;re&nbsp;no duplicates in url library.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Interactive](../../tag/interactive/README.md)]
-
-### Similar Questions
-  1. [Web Crawler Multithreaded](../web-crawler-multithreaded) (Medium)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use DFS/BFS to search start from the startURL. Remember to get rid of duplicate URLs.
-</details>
diff --git a/problems/where-will-the-ball-fall/README.md b/problems/where-will-the-ball-fall/README.md
deleted file mode 100644
index 5d79d418e..000000000
--- a/problems/where-will-the-ball-fall/README.md
+++ /dev/null
@@ -1,84 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../maximum-number-of-eaten-apples "Maximum Number of Eaten Apples")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-xor-with-an-element-from-array "Maximum XOR With an Element From Array")
-
-## [1706. Where Will the Ball Fall (Medium)](https://leetcode.com/problems/where-will-the-ball-fall "球会落何处")
-
-<p>You have a 2-D <code>grid</code> of size <code>m x n</code> representing a box, and you have <code>n</code> balls. The box is open on the top and bottom sides.</p>
-
-<p>Each cell in the box has a diagonal board spanning two corners of the cell that can redirect a ball to the right or to the left.</p>
-
-<ul>
-	<li>A board that redirects the ball to the right spans the top-left corner to the bottom-right corner and is represented in the grid as <code>1</code>.</li>
-	<li>A board that redirects the ball to the left spans the top-right corner to the bottom-left corner and is represented in the grid as <code>-1</code>.</li>
-</ul>
-
-<p>We drop one ball at the top of each column of the box. Each ball can get stuck in the box or fall out of the bottom. A ball gets stuck if it hits a &quot;V&quot; shaped pattern between two boards or if a board redirects the ball into either wall of the box.</p>
-
-<p>Return <em>an array </em><code>answer</code><em> of size </em><code>n</code><em> where </em><code>answer[i]</code><em> is the column that the ball falls out of at the bottom after dropping the ball from the </em><code>i<sup>th</sup></code><em> column at the top, or <code>-1</code><em> if the ball gets stuck in the box</em>.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/09/26/ball.jpg" style="width: 500px; height: 385px;" /></strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,1,-1,-1],[1,1,1,-1,-1],[-1,-1,-1,1,1],[1,1,1,1,-1],[-1,-1,-1,-1,-1]]
-<strong>Output:</strong> [1,-1,-1,-1,-1]
-<strong>Explanation:</strong> This example is shown in the photo.
-Ball b0 is dropped at column 0 and falls out of the box at column 1.
-Ball b1 is dropped at column 1 and will get stuck in the box between column 2 and 3 and row 1.
-Ball b2 is dropped at column 2 and will get stuck on the box between column 2 and 3 and row 0.
-Ball b3 is dropped at column 3 and will get stuck on the box between column 2 and 3 and row 0.
-Ball b4 is dropped at column 4 and will get stuck on the box between column 2 and 3 and row 1.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[-1]]
-<strong>Output:</strong> [-1]
-<strong>Explanation:</strong> The ball gets stuck against the left wall.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> grid = [[1,1,1,1,1,1],[-1,-1,-1,-1,-1,-1],[1,1,1,1,1,1],[-1,-1,-1,-1,-1,-1]]
-<strong>Output:</strong> [0,1,2,3,4,-1]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == grid.length</code></li>
-	<li><code>n == grid[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 100</code></li>
-	<li><code>grid[i][j]</code> is <code>1</code> or <code>-1</code>.</li>
-</ul>
-
-### Related Topics
-  [[Depth-First Search](../../tag/depth-first-search/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-  [[Simulation](../../tag/simulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Use DFS.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Traverse the path of the ball downwards until you reach the bottom or get stuck.
-</details>
diff --git a/problems/widest-pair-of-indices-with-equal-range-sum/README.md b/problems/widest-pair-of-indices-with-equal-range-sum/README.md
deleted file mode 100644
index 03bb08145..000000000
--- a/problems/widest-pair-of-indices-with-equal-range-sum/README.md
+++ /dev/null
@@ -1,35 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../find-array-given-subset-sums "Find Array Given Subset Sums")
-　　　　　　　　　　　　　　　　
-[Next >](../minimum-difference-between-highest-and-lowest-of-k-scores "Minimum Difference Between Highest and Lowest of K Scores")
-
-## [1983. Widest Pair of Indices With Equal Range Sum (Medium)](https://leetcode.com/problems/widest-pair-of-indices-with-equal-range-sum "")
-
-
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Keep prefix sums of both arrays.
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Can the difference between the prefix sums at an index help us?
-</details>
-
-<details>
-<summary>Hint 3</summary>
-What happens if the difference between the two prefix sums at an index a is x, and x again at a different index b?
-</details>
-
-<details>
-<summary>Hint 4</summary>
-This means that the sum of nums1 from index a + 1 to index b is equal to the sum of nums2 from index a + 1 to index b.
-</details>
diff --git a/problems/widest-vertical-area-between-two-points-containing-no-points/README.md b/problems/widest-vertical-area-between-two-points-containing-no-points/README.md
deleted file mode 100644
index 9e0d052f3..000000000
--- a/problems/widest-vertical-area-between-two-points-containing-no-points/README.md
+++ /dev/null
@@ -1,59 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../sort-array-by-increasing-frequency "Sort Array by Increasing Frequency")
-　　　　　　　　　　　　　　　　
-[Next >](../count-substrings-that-differ-by-one-character "Count Substrings That Differ by One Character")
-
-## [1637. Widest Vertical Area Between Two Points Containing No Points (Medium)](https://leetcode.com/problems/widest-vertical-area-between-two-points-containing-no-points "两点之间不包含任何点的最宽垂直面积")
-
-<p>Given <code>n</code> <code>points</code> on a 2D plane where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>, Return<em>&nbsp;the <strong>widest vertical area</strong> between two points such that no points are inside the area.</em></p>
-
-<p>A <strong>vertical area</strong> is an area of fixed-width extending infinitely along the y-axis (i.e., infinite height). The <strong>widest vertical area</strong> is the one with the maximum width.</p>
-
-<p>Note that points <strong>on the edge</strong> of a vertical area <strong>are not</strong> considered included in the area.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/09/19/points3.png" style="width: 276px; height: 371px;" />​
-<pre>
-<strong>Input:</strong> points = [[8,7],[9,9],[7,4],[9,7]]
-<strong>Output:</strong> 1
-<strong>Explanation:</strong> Both the red and the blue area are optimal.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> points = [[3,1],[9,0],[1,0],[1,4],[5,3],[8,8]]
-<strong>Output:</strong> 3
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>n == points.length</code></li>
-	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
-	<li><code>points[i].length == 2</code></li>
-	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub>&nbsp;&lt;= 10<sup>9</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Try sorting the points
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Think is the y-axis of a point relevant
-</details>
diff --git a/problems/wiggle-sort-ii/README.md b/problems/wiggle-sort-ii/README.md
deleted file mode 100644
index b38cdbed6..000000000
--- a/problems/wiggle-sort-ii/README.md
+++ /dev/null
@@ -1,56 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-connected-components-in-an-undirected-graph "Number of Connected Components in an Undirected Graph")
-　　　　　　　　　　　　　　　　
-[Next >](../maximum-size-subarray-sum-equals-k "Maximum Size Subarray Sum Equals k")
-
-## [324. Wiggle Sort II (Medium)](https://leetcode.com/problems/wiggle-sort-ii "摆动排序 II")
-
-<p>Given an integer array <code>nums</code>, reorder it such that <code>nums[0] &lt; nums[1] &gt; nums[2] &lt; nums[3]...</code>.</p>
-
-<p>You may assume the input array always has a valid answer.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,5,1,1,6,4]
-<strong>Output:</strong> [1,6,1,5,1,4]
-<strong>Explanation:</strong> [1,4,1,5,1,6] is also accepted.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,3,2,2,3,1]
-<strong>Output:</strong> [2,3,1,3,1,2]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 5000</code></li>
-	<li>It is guaranteed that there will be an answer for the given input <code>nums</code>.</li>
-</ul>
-
-<p>&nbsp;</p>
-<strong>Follow Up:</strong> Can you do it in <code>O(n)</code> time and/or <strong>in-place</strong> with <code>O(1)</code> extra space?
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Divide and Conquer](../../tag/divide-and-conquer/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-  [[Quickselect](../../tag/quickselect/README.md)]
-
-### Similar Questions
-  1. [Sort Colors](../sort-colors) (Medium)
-  1. [Kth Largest Element in an Array](../kth-largest-element-in-an-array) (Medium)
-  1. [Wiggle Sort](../wiggle-sort) (Medium)
-  1. [Array With Elements Not Equal to Average of Neighbors](../array-with-elements-not-equal-to-average-of-neighbors) (Medium)
diff --git a/problems/wiggle-sort-ii/wiggle_sort_ii.go b/problems/wiggle-sort-ii/wiggle_sort_ii.go
deleted file mode 100644
index fb18dd407..000000000
--- a/problems/wiggle-sort-ii/wiggle_sort_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem324
diff --git a/problems/wiggle-sort-ii/wiggle_sort_ii_test.go b/problems/wiggle-sort-ii/wiggle_sort_ii_test.go
deleted file mode 100644
index fb18dd407..000000000
--- a/problems/wiggle-sort-ii/wiggle_sort_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem324
diff --git a/problems/wiggle-sort/README.md b/problems/wiggle-sort/README.md
deleted file mode 100644
index f8361134c..000000000
--- a/problems/wiggle-sort/README.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../perfect-squares "Perfect Squares")
-　　　　　　　　　　　　　　　　
-[Next >](../zigzag-iterator "Zigzag Iterator")
-
-## [280. Wiggle Sort (Medium)](https://leetcode.com/problems/wiggle-sort "摆动排序")
-
-<p>Given an unsorted array <code>nums</code>, reorder it <b>in-place</b> such that <code>nums[0] &lt;= nums[1] &gt;= nums[2] &lt;= nums[3]...</code>.</p>
-
-<p><b>Example:</b></p>
-
-<pre>
-<b>Input:</b> <code>nums = [3,5,2,1,6,4]</code>
-<b>Output:</b> One possible answer is [3,5,1,6,2,4]</pre>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Sort Colors](../sort-colors) (Medium)
-  1. [Wiggle Sort II](../wiggle-sort-ii) (Medium)
diff --git a/problems/wiggle-sort/wiggle_sort.go b/problems/wiggle-sort/wiggle_sort.go
deleted file mode 100644
index 9e38b1ccb..000000000
--- a/problems/wiggle-sort/wiggle_sort.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem280
diff --git a/problems/wiggle-sort/wiggle_sort_test.go b/problems/wiggle-sort/wiggle_sort_test.go
deleted file mode 100644
index 9e38b1ccb..000000000
--- a/problems/wiggle-sort/wiggle_sort_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem280
diff --git a/problems/wiggle-subsequence/README.md b/problems/wiggle-subsequence/README.md
deleted file mode 100644
index 238eb4b28..000000000
--- a/problems/wiggle-subsequence/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../guess-number-higher-or-lower-ii "Guess Number Higher or Lower II")
-　　　　　　　　　　　　　　　　
-[Next >](../combination-sum-iv "Combination Sum IV")
-
-## [376. Wiggle Subsequence (Medium)](https://leetcode.com/problems/wiggle-subsequence "摆动序列")
-
-<p>A <strong>wiggle sequence</strong> is a sequence where the differences between successive numbers strictly alternate between positive and negative. The first difference (if one exists) may be either positive or negative. A sequence with one element and a sequence with two non-equal elements are trivially wiggle sequences.</p>
-
-<ul>
-	<li>For example, <code>[1, 7, 4, 9, 2, 5]</code> is a <strong>wiggle sequence</strong> because the differences <code>(6, -3, 5, -7, 3)</code> alternate between positive and negative.</li>
-	<li>In contrast, <code>[1, 4, 7, 2, 5]</code> and <code>[1, 7, 4, 5, 5]</code> are not wiggle sequences. The first is not because its first two differences are positive, and the second is not because its last difference is zero.</li>
-</ul>
-
-<p>A <strong>subsequence</strong> is obtained by deleting some elements (possibly zero) from the original sequence, leaving the remaining elements in their original order.</p>
-
-<p>Given an integer array <code>nums</code>, return <em>the length of the longest <strong>wiggle subsequence</strong> of </em><code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,7,4,9,2,5]
-<strong>Output:</strong> 6
-<strong>Explanation:</strong> The entire sequence is a wiggle sequence with differences (6, -3, 5, -7, 3).
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,17,5,10,13,15,10,5,16,8]
-<strong>Output:</strong> 7
-<strong>Explanation:</strong> There are several subsequences that achieve this length.
-One is [1, 17, 10, 13, 10, 16, 8] with differences (16, -7, 3, -3, 6, -8).
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> nums = [1,2,3,4,5,6,7,8,9]
-<strong>Output:</strong> 2
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
-	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you solve this in <code>O(n)</code> time?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Greedy](../../tag/greedy/README.md)]
-
-### Similar Questions
-  1. [Rearrange Array Elements by Sign](../rearrange-array-elements-by-sign) (Medium)
diff --git a/problems/wiggle-subsequence/wiggle_subsequence.go b/problems/wiggle-subsequence/wiggle_subsequence.go
deleted file mode 100644
index 54117e796..000000000
--- a/problems/wiggle-subsequence/wiggle_subsequence.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem376
diff --git a/problems/wiggle-subsequence/wiggle_subsequence_test.go b/problems/wiggle-subsequence/wiggle_subsequence_test.go
deleted file mode 100644
index 54117e796..000000000
--- a/problems/wiggle-subsequence/wiggle_subsequence_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem376
diff --git a/problems/wildcard-matching/README.md b/problems/wildcard-matching/README.md
deleted file mode 100644
index 1230d3ff7..000000000
--- a/problems/wildcard-matching/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../multiply-strings "Multiply Strings")
-　　　　　　　　　　　　　　　　
-[Next >](../jump-game-ii "Jump Game II")
-
-## [44. Wildcard Matching (Hard)](https://leetcode.com/problems/wildcard-matching "通配符匹配")
-
-<p>Given an input string (<code>s</code>) and a pattern (<code>p</code>), implement wildcard pattern matching with support for <code>&#39;?&#39;</code> and <code>&#39;*&#39;</code> where:</p>
-
-<ul>
-	<li><code>&#39;?&#39;</code> Matches any single character.</li>
-	<li><code>&#39;*&#39;</code> Matches any sequence of characters (including the empty sequence).</li>
-</ul>
-
-<p>The matching should cover the <strong>entire</strong> input string (not partial).</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aa&quot;, p = &quot;a&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong> &quot;a&quot; does not match the entire string &quot;aa&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;aa&quot;, p = &quot;*&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>&nbsp;&#39;*&#39; matches any sequence.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;cb&quot;, p = &quot;?a&quot;
-<strong>Output:</strong> false
-<strong>Explanation:</strong>&nbsp;&#39;?&#39; matches &#39;c&#39;, but the second letter is &#39;a&#39;, which does not match &#39;b&#39;.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;adceb&quot;, p = &quot;*a*b&quot;
-<strong>Output:</strong> true
-<strong>Explanation:</strong>&nbsp;The first &#39;*&#39; matches the empty sequence, while the second &#39;*&#39; matches the substring &quot;dce&quot;.
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;acdcb&quot;, p = &quot;a*c?b&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>0 &lt;= s.length, p.length &lt;= 2000</code></li>
-	<li><code>s</code> contains only lowercase English letters.</li>
-	<li><code>p</code> contains only lowercase English letters, <code>&#39;?&#39;</code> or <code>&#39;*&#39;</code>.</li>
-</ul>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Recursion](../../tag/recursion/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Regular Expression Matching](../regular-expression-matching) (Hard)
diff --git a/problems/wildcard-matching/wildcard_matching.go b/problems/wildcard-matching/wildcard_matching.go
deleted file mode 100644
index 1a0acc80c..000000000
--- a/problems/wildcard-matching/wildcard_matching.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem44
diff --git a/problems/wildcard-matching/wildcard_matching_test.go b/problems/wildcard-matching/wildcard_matching_test.go
deleted file mode 100644
index 1a0acc80c..000000000
--- a/problems/wildcard-matching/wildcard_matching_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem44
diff --git a/problems/winning-candidate/README.md b/problems/winning-candidate/README.md
deleted file mode 100644
index d5fb85d36..000000000
--- a/problems/winning-candidate/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../squirrel-simulation "Squirrel Simulation")
-　　　　　　　　　　　　　　　　
-[Next >](../distribute-candies "Distribute Candies")
-
-## [574. Winning Candidate (Medium)](https://leetcode.com/problems/winning-candidate "当选者")
-
-<p>Table: <code>Candidate</code></p>
-
-<pre>
-+-----+---------+
-| id  | Name    |
-+-----+---------+
-| 1   | A       |
-| 2   | B       |
-| 3   | C       |
-| 4   | D       |
-| 5   | E       |
-+-----+---------+  
-</pre>
-
-<p>Table: <code>Vote</code></p>
-
-<pre>
-+-----+--------------+
-| id  | CandidateId  |
-+-----+--------------+
-| 1   |     2        |
-| 2   |     4        |
-| 3   |     3        |
-| 4   |     2        |
-| 5   |     5        |
-+-----+--------------+
-id is the auto-increment primary key,
-CandidateId is the id appeared in Candidate table.
-</pre>
-
-<p>Write a sql to find the name of the winning candidate, the above example will return the winner <code>B</code>.</p>
-
-<pre>
-+------+
-| Name |
-+------+
-| B    |
-+------+
-</pre>
-
-<p><b>Notes:</b></p>
-
-<ol>
-	<li>You may assume <b>there is no tie</b>, in other words there will be <b>only one</b> winning candidate.</li>
-</ol>
-
-<p>&nbsp;</p>
-
-### Related Topics
-  [[Database](../../tag/database/README.md)]
diff --git a/problems/winning-candidate/mysql_schemas.sql b/problems/winning-candidate/mysql_schemas.sql
deleted file mode 100644
index 38b3cc5f1..000000000
--- a/problems/winning-candidate/mysql_schemas.sql
+++ /dev/null
@@ -1,14 +0,0 @@
-Create table If Not Exists Candidate (id int, Name varchar(255));
-Create table If Not Exists Vote (id int, CandidateId int);
-Truncate table Candidate;
-insert into Candidate (id, Name) values ('1', 'A');
-insert into Candidate (id, Name) values ('2', 'B');
-insert into Candidate (id, Name) values ('3', 'C');
-insert into Candidate (id, Name) values ('4', 'D');
-insert into Candidate (id, Name) values ('5', 'E');
-Truncate table Vote;
-insert into Vote (id, CandidateId) values ('1', '2');
-insert into Vote (id, CandidateId) values ('2', '4');
-insert into Vote (id, CandidateId) values ('3', '3');
-insert into Vote (id, CandidateId) values ('4', '2');
-insert into Vote (id, CandidateId) values ('5', '5');
diff --git a/problems/winning-candidate/winning_candidate.sql b/problems/winning-candidate/winning_candidate.sql
deleted file mode 100644
index 5cf961c52..000000000
--- a/problems/winning-candidate/winning_candidate.sql
+++ /dev/null
@@ -1,17 +0,0 @@
-# Write your MySQL query statement below
-
-SELECT `name` AS 'Name'
-FROM
-  Candidate
-  JOIN (
-         SELECT Candidateid
-         FROM
-           Vote
-         GROUP BY
-           Candidateid
-         ORDER BY
-           COUNT(*) DESC
-         LIMIT 1
-       ) AS winner
-WHERE
-  Candidate.id = winner.Candidateid;
diff --git a/problems/word-abbreviation/README.md b/problems/word-abbreviation/README.md
deleted file mode 100644
index 7fd9f8a67..000000000
--- a/problems/word-abbreviation/README.md
+++ /dev/null
@@ -1,47 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../beautiful-arrangement "Beautiful Arrangement")
-　　　　　　　　　　　　　　　　
-[Next >](../random-pick-with-weight "Random Pick with Weight")
-
-## [527. Word Abbreviation (Hard)](https://leetcode.com/problems/word-abbreviation "单词缩写")
-
-<p>Given an array of n distinct non-empty strings, you need to generate <b>minimal</b> possible abbreviations for every word following rules below.</p>
-
-<ol>
-<li>Begin with the first character and then the number of characters abbreviated, which followed by the last character.</li>
-<li>If there are any conflict, that is more than one words share the same abbreviation, a longer prefix is used instead of only the first character until making the map from word to abbreviation become unique. In other words, a final abbreviation cannot map to more than one original words.</li>
-<li> If the abbreviation doesn't make the word shorter, then keep it as original.</li>
-</ol>
-
-<p><b>Example:</b><br />
-<pre>
-<b>Input:</b> ["like", "god", "internal", "me", "internet", "interval", "intension", "face", "intrusion"]
-<b>Output:</b> ["l2e","god","internal","me","i6t","interval","inte4n","f2e","intr4n"]
-</pre>
-</p>
-
-
-<b>Note:</b> 
-<ol>
-<li> Both n and the length of each word will not exceed 400.</li>
-<li> The length of each word is greater than 1.</li>
-<li> The words consist of lowercase English letters only.</li>
-<li> The return answers should be <b>in the same order</b> as the original array.</li>
-</ol>
-
-### Related Topics
-  [[Greedy](../../tag/greedy/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Sorting](../../tag/sorting/README.md)]
-
-### Similar Questions
-  1. [Valid Word Abbreviation](../valid-word-abbreviation) (Easy)
-  1. [Minimum Unique Word Abbreviation](../minimum-unique-word-abbreviation) (Hard)
diff --git a/problems/word-abbreviation/word_abbreviation.go b/problems/word-abbreviation/word_abbreviation.go
deleted file mode 100644
index 4c7506599..000000000
--- a/problems/word-abbreviation/word_abbreviation.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem527
diff --git a/problems/word-abbreviation/word_abbreviation_test.go b/problems/word-abbreviation/word_abbreviation_test.go
deleted file mode 100644
index 4c7506599..000000000
--- a/problems/word-abbreviation/word_abbreviation_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem527
diff --git a/problems/word-break-ii/README.md b/problems/word-break-ii/README.md
deleted file mode 100644
index 2442e9ffc..000000000
--- a/problems/word-break-ii/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-break "Word Break")
-　　　　　　　　　　　　　　　　
-[Next >](../linked-list-cycle "Linked List Cycle")
-
-## [140. Word Break II (Hard)](https://leetcode.com/problems/word-break-ii "单词拆分 II")
-
-<p>Given a string <code>s</code> and a dictionary of strings <code>wordDict</code>, add spaces in <code>s</code> to construct a sentence where each word is a valid dictionary word. Return all such possible sentences in <strong>any order</strong>.</p>
-
-<p><strong>Note</strong> that the same word in the dictionary may be reused multiple times in the segmentation.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;catsanddog&quot;, wordDict = [&quot;cat&quot;,&quot;cats&quot;,&quot;and&quot;,&quot;sand&quot;,&quot;dog&quot;]
-<strong>Output:</strong> [&quot;cats and dog&quot;,&quot;cat sand dog&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;pineapplepenapple&quot;, wordDict = [&quot;apple&quot;,&quot;pen&quot;,&quot;applepen&quot;,&quot;pine&quot;,&quot;pineapple&quot;]
-<strong>Output:</strong> [&quot;pine apple pen apple&quot;,&quot;pineapple pen apple&quot;,&quot;pine applepen apple&quot;]
-<strong>Explanation:</strong> Note that you are allowed to reuse a dictionary word.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;catsandog&quot;, wordDict = [&quot;cats&quot;,&quot;dog&quot;,&quot;sand&quot;,&quot;and&quot;,&quot;cat&quot;]
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 20</code></li>
-	<li><code>1 &lt;= wordDict.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= wordDict[i].length &lt;= 10</code></li>
-	<li><code>s</code> and <code>wordDict[i]</code> consist of only lowercase English letters.</li>
-	<li>All the strings of <code>wordDict</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-
-### Similar Questions
-  1. [Word Break](../word-break) (Medium)
-  1. [Concatenated Words](../concatenated-words) (Hard)
diff --git a/problems/word-break-ii/word_break_ii.go b/problems/word-break-ii/word_break_ii.go
deleted file mode 100644
index 98e85ad6b..000000000
--- a/problems/word-break-ii/word_break_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem140
diff --git a/problems/word-break-ii/word_break_ii_test.go b/problems/word-break-ii/word_break_ii_test.go
deleted file mode 100644
index 98e85ad6b..000000000
--- a/problems/word-break-ii/word_break_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem140
diff --git a/problems/word-break/README.md b/problems/word-break/README.md
deleted file mode 100644
index 13cb790a8..000000000
--- a/problems/word-break/README.md
+++ /dev/null
@@ -1,62 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../copy-list-with-random-pointer "Copy List with Random Pointer")
-　　　　　　　　　　　　　　　　
-[Next >](../word-break-ii "Word Break II")
-
-## [139. Word Break (Medium)](https://leetcode.com/problems/word-break "单词拆分")
-
-<p>Given a string <code>s</code> and a dictionary of strings <code>wordDict</code>, return <code>true</code> if <code>s</code> can be segmented into a space-separated sequence of one or more dictionary words.</p>
-
-<p><strong>Note</strong> that the same word in the dictionary may be reused multiple times in the segmentation.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;leetcode&quot;, wordDict = [&quot;leet&quot;,&quot;code&quot;]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Return true because &quot;leetcode&quot; can be segmented as &quot;leet code&quot;.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;applepenapple&quot;, wordDict = [&quot;apple&quot;,&quot;pen&quot;]
-<strong>Output:</strong> true
-<strong>Explanation:</strong> Return true because &quot;applepenapple&quot; can be segmented as &quot;apple pen apple&quot;.
-Note that you are allowed to reuse a dictionary word.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;catsandog&quot;, wordDict = [&quot;cats&quot;,&quot;dog&quot;,&quot;sand&quot;,&quot;and&quot;,&quot;cat&quot;]
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 300</code></li>
-	<li><code>1 &lt;= wordDict.length &lt;= 1000</code></li>
-	<li><code>1 &lt;= wordDict[i].length &lt;= 20</code></li>
-	<li><code>s</code> and <code>wordDict[i]</code> consist of only lowercase English letters.</li>
-	<li>All the strings of <code>wordDict</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Trie](../../tag/trie/README.md)]
-  [[Memoization](../../tag/memoization/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
-
-### Similar Questions
-  1. [Word Break II](../word-break-ii) (Hard)
diff --git a/problems/word-break/word_break.go b/problems/word-break/word_break.go
deleted file mode 100644
index 59cf66b39..000000000
--- a/problems/word-break/word_break.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package problem139
-
-func wordBreak(s string, wordDict []string) bool {
-	wm, l := make(map[string]bool), len(s)
-	for _, w := range wordDict {
-		wm[w] = true
-	}
-	dp := make([]bool, l+1)
-	dp[0] = true
-	for i := 1; i <= l; i++ {
-		for j := 0; j < i; j++ {
-			if dp[j] && wm[s[j:i]] {
-				dp[i] = true
-				break
-			}
-		}
-	}
-	return dp[l]
-}
diff --git a/problems/word-break/word_break_test.go b/problems/word-break/word_break_test.go
deleted file mode 100644
index a314c3d00..000000000
--- a/problems/word-break/word_break_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem139
-
-import "testing"
-
-type testType struct {
-	in       string
-	wordDict []string
-	want     bool
-}
-
-func TestWordBreak(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:       "leetcode",
-			wordDict: []string{"leet", "code"},
-			want:     true,
-		},
-		{
-			in:       "applepenapple",
-			wordDict: []string{"apple", "pen"},
-			want:     true,
-		},
-		{
-			in:       "catsandog",
-			wordDict: []string{"cats", "dog", "sand", "and", "cat"},
-			want:     false,
-		},
-	}
-	for _, tt := range tests {
-		got := wordBreak(tt.in, tt.wordDict)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/word-frequency/README.md b/problems/word-frequency/README.md
deleted file mode 100644
index 6948c18ae..000000000
--- a/problems/word-frequency/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../number-of-1-bits "Number of 1 Bits")
-　　　　　　　　　　　　　　　　
-[Next >](../valid-phone-numbers "Valid Phone Numbers")
-
-## [192. Word Frequency (Medium)](https://leetcode.com/problems/word-frequency "统计词频")
-
-<p>Write a bash script to calculate the frequency of each word in a text file <code>words.txt</code>.</p>
-
-<p>For simplicity sake, you may assume:</p>
-
-<ul>
-	<li><code>words.txt</code> contains only lowercase characters and space <code>&#39; &#39;</code> characters.</li>
-	<li>Each word must consist of lowercase characters only.</li>
-	<li>Words are separated by one or more whitespace characters.</li>
-</ul>
-
-<p><strong>Example:</strong></p>
-
-<p>Assume that <code>words.txt</code> has the following content:</p>
-
-<pre>
-the day is sunny the the
-the sunny is is
-</pre>
-
-<p>Your script should output the following, sorted by descending frequency:</p>
-
-<pre>
-the 4
-is 3
-sunny 2
-day 1
-</pre>
-
-<p><b>Note:</b></p>
-
-<ul>
-	<li>Don&#39;t worry about handling ties, it is guaranteed that each word&#39;s frequency count is unique.</li>
-	<li>Could you write it in one-line using <a href="http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-4.html">Unix pipes</a>?</li>
-</ul>
-
-### Related Topics
-  [[Shell](../../tag/shell/README.md)]
-
-### Similar Questions
-  1. [Top K Frequent Elements](../top-k-frequent-elements) (Medium)
diff --git a/problems/word-frequency/word_frequency.bash b/problems/word-frequency/word_frequency.bash
deleted file mode 100755
index fe817eebd..000000000
--- a/problems/word-frequency/word_frequency.bash
+++ /dev/null
@@ -1,5 +0,0 @@
-#!/usr/bin/env bash
-
-# Read from the file words.txt and output the word frequency list to stdout.
-
-awk '{for(i=1;i<=NF;i++) a[$i]++} END {for(k in a) print k,a[k]}' words.txt | sort -k2 -nr
diff --git a/problems/word-frequency/words.txt b/problems/word-frequency/words.txt
deleted file mode 100644
index 18d52475f..000000000
--- a/problems/word-frequency/words.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-the day is sunny the the
-the sunny is is
diff --git a/problems/word-ladder-ii/README.md b/problems/word-ladder-ii/README.md
deleted file mode 100644
index fd36368df..000000000
--- a/problems/word-ladder-ii/README.md
+++ /dev/null
@@ -1,63 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../valid-palindrome "Valid Palindrome")
-　　　　　　　　　　　　　　　　
-[Next >](../word-ladder "Word Ladder")
-
-## [126. Word Ladder II (Hard)](https://leetcode.com/problems/word-ladder-ii "单词接龙 II")
-
-<p>A <strong>transformation sequence</strong> from word <code>beginWord</code> to word <code>endWord</code> using a dictionary <code>wordList</code> is a sequence of words <code>beginWord -&gt; s<sub>1</sub> -&gt; s<sub>2</sub> -&gt; ... -&gt; s<sub>k</sub></code> such that:</p>
-
-<ul>
-	<li>Every adjacent pair of words differs by a single letter.</li>
-	<li>Every <code>s<sub>i</sub></code> for <code>1 &lt;= i &lt;= k</code> is in <code>wordList</code>. Note that <code>beginWord</code> does not need to be in <code>wordList</code>.</li>
-	<li><code>s<sub>k</sub> == endWord</code></li>
-</ul>
-
-<p>Given two words, <code>beginWord</code> and <code>endWord</code>, and a dictionary <code>wordList</code>, return <em>all the <strong>shortest transformation sequences</strong> from</em> <code>beginWord</code> <em>to</em> <code>endWord</code><em>, or an empty list if no such sequence exists. Each sequence should be returned as a list of the words </em><code>[beginWord, s<sub>1</sub>, s<sub>2</sub>, ..., s<sub>k</sub>]</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> beginWord = &quot;hit&quot;, endWord = &quot;cog&quot;, wordList = [&quot;hot&quot;,&quot;dot&quot;,&quot;dog&quot;,&quot;lot&quot;,&quot;log&quot;,&quot;cog&quot;]
-<strong>Output:</strong> [[&quot;hit&quot;,&quot;hot&quot;,&quot;dot&quot;,&quot;dog&quot;,&quot;cog&quot;],[&quot;hit&quot;,&quot;hot&quot;,&quot;lot&quot;,&quot;log&quot;,&quot;cog&quot;]]
-<strong>Explanation:</strong>&nbsp;There are 2 shortest transformation sequences:
-&quot;hit&quot; -&gt; &quot;hot&quot; -&gt; &quot;dot&quot; -&gt; &quot;dog&quot; -&gt; &quot;cog&quot;
-&quot;hit&quot; -&gt; &quot;hot&quot; -&gt; &quot;lot&quot; -&gt; &quot;log&quot; -&gt; &quot;cog&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> beginWord = &quot;hit&quot;, endWord = &quot;cog&quot;, wordList = [&quot;hot&quot;,&quot;dot&quot;,&quot;dog&quot;,&quot;lot&quot;,&quot;log&quot;]
-<strong>Output:</strong> []
-<strong>Explanation:</strong> The endWord &quot;cog&quot; is not in wordList, therefore there is no valid transformation sequence.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= beginWord.length &lt;= 5</code></li>
-	<li><code>endWord.length == beginWord.length</code></li>
-	<li><code>1 &lt;= wordList.length &lt;= 1000</code></li>
-	<li><code>wordList[i].length == beginWord.length</code></li>
-	<li><code>beginWord</code>, <code>endWord</code>, and <code>wordList[i]</code> consist of lowercase English letters.</li>
-	<li><code>beginWord != endWord</code></li>
-	<li>All the words in <code>wordList</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Word Ladder](../word-ladder) (Hard)
diff --git a/problems/word-ladder-ii/word_ladder_ii.go b/problems/word-ladder-ii/word_ladder_ii.go
deleted file mode 100644
index 695cdef91..000000000
--- a/problems/word-ladder-ii/word_ladder_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem126
diff --git a/problems/word-ladder-ii/word_ladder_ii_test.go b/problems/word-ladder-ii/word_ladder_ii_test.go
deleted file mode 100644
index 695cdef91..000000000
--- a/problems/word-ladder-ii/word_ladder_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem126
diff --git a/problems/word-ladder/README.md b/problems/word-ladder/README.md
deleted file mode 100644
index 8a73d975c..000000000
--- a/problems/word-ladder/README.md
+++ /dev/null
@@ -1,61 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-ladder-ii "Word Ladder II")
-　　　　　　　　　　　　　　　　
-[Next >](../longest-consecutive-sequence "Longest Consecutive Sequence")
-
-## [127. Word Ladder (Hard)](https://leetcode.com/problems/word-ladder "单词接龙")
-
-<p>A <strong>transformation sequence</strong> from word <code>beginWord</code> to word <code>endWord</code> using a dictionary <code>wordList</code> is a sequence of words <code>beginWord -&gt; s<sub>1</sub> -&gt; s<sub>2</sub> -&gt; ... -&gt; s<sub>k</sub></code> such that:</p>
-
-<ul>
-	<li>Every adjacent pair of words differs by a single letter.</li>
-	<li>Every <code>s<sub>i</sub></code> for <code>1 &lt;= i &lt;= k</code> is in <code>wordList</code>. Note that <code>beginWord</code> does not need to be in <code>wordList</code>.</li>
-	<li><code>s<sub>k</sub> == endWord</code></li>
-</ul>
-
-<p>Given two words, <code>beginWord</code> and <code>endWord</code>, and a dictionary <code>wordList</code>, return <em>the <strong>number of words</strong> in the <strong>shortest transformation sequence</strong> from</em> <code>beginWord</code> <em>to</em> <code>endWord</code><em>, or </em><code>0</code><em> if no such sequence exists.</em></p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> beginWord = &quot;hit&quot;, endWord = &quot;cog&quot;, wordList = [&quot;hot&quot;,&quot;dot&quot;,&quot;dog&quot;,&quot;lot&quot;,&quot;log&quot;,&quot;cog&quot;]
-<strong>Output:</strong> 5
-<strong>Explanation:</strong> One shortest transformation sequence is &quot;hit&quot; -&gt; &quot;hot&quot; -&gt; &quot;dot&quot; -&gt; &quot;dog&quot; -&gt; cog&quot;, which is 5 words long.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> beginWord = &quot;hit&quot;, endWord = &quot;cog&quot;, wordList = [&quot;hot&quot;,&quot;dot&quot;,&quot;dog&quot;,&quot;lot&quot;,&quot;log&quot;]
-<strong>Output:</strong> 0
-<strong>Explanation:</strong> The endWord &quot;cog&quot; is not in wordList, therefore there is no valid transformation sequence.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= beginWord.length &lt;= 10</code></li>
-	<li><code>endWord.length == beginWord.length</code></li>
-	<li><code>1 &lt;= wordList.length &lt;= 5000</code></li>
-	<li><code>wordList[i].length == beginWord.length</code></li>
-	<li><code>beginWord</code>, <code>endWord</code>, and <code>wordList[i]</code> consist of lowercase English letters.</li>
-	<li><code>beginWord != endWord</code></li>
-	<li>All the words in <code>wordList</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Breadth-First Search](../../tag/breadth-first-search/README.md)]
-
-### Similar Questions
-  1. [Word Ladder II](../word-ladder-ii) (Hard)
-  1. [Minimum Genetic Mutation](../minimum-genetic-mutation) (Medium)
diff --git a/problems/word-ladder/word_ladder.go b/problems/word-ladder/word_ladder.go
deleted file mode 100644
index 51c2f7758..000000000
--- a/problems/word-ladder/word_ladder.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem127
diff --git a/problems/word-ladder/word_ladder_test.go b/problems/word-ladder/word_ladder_test.go
deleted file mode 100644
index 51c2f7758..000000000
--- a/problems/word-ladder/word_ladder_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem127
diff --git a/problems/word-pattern-ii/README.md b/problems/word-pattern-ii/README.md
deleted file mode 100644
index b7e543f01..000000000
--- a/problems/word-pattern-ii/README.md
+++ /dev/null
@@ -1,46 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../word-pattern "Word Pattern")
-　　　　　　　　　　　　　　　　
-[Next >](../nim-game "Nim Game")
-
-## [291. Word Pattern II (Medium)](https://leetcode.com/problems/word-pattern-ii "单词规律 II")
-
-<p>Given a <code>pattern</code> and a string <code>str</code>, find if <code>str</code> follows the same pattern.</p>
-
-<p>Here <b>follow</b> means a full match, such that there is a bijection between a letter in <code>pattern</code> and a <b>non-empty</b> substring in <code>str</code>.</p>
-
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input: </strong>pattern = <code>&quot;abab&quot;</code>, str = <code>&quot;redblueredblue&quot;</code>
-<strong>Output:</strong> true</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input: </strong>pattern = pattern = <code>&quot;aaaa&quot;</code>, str = <code>&quot;asdasdasdasd&quot;</code>
-<strong>Output:</strong> true</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> pattern = <code>&quot;aabb&quot;</code>, str = <code>&quot;xyzabcxzyabc&quot;</code>
-<strong>Output:</strong> false
-</pre>
-
-<p><b>Notes:</b><br />
-You may assume both <code>pattern</code> and <code>str</code> contains only lowercase letters.</p>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-
-### Similar Questions
-  1. [Word Pattern](../word-pattern) (Easy)
diff --git a/problems/word-pattern-ii/word_pattern_ii.go b/problems/word-pattern-ii/word_pattern_ii.go
deleted file mode 100644
index d31ac2bb8..000000000
--- a/problems/word-pattern-ii/word_pattern_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem291
diff --git a/problems/word-pattern-ii/word_pattern_ii_test.go b/problems/word-pattern-ii/word_pattern_ii_test.go
deleted file mode 100644
index d31ac2bb8..000000000
--- a/problems/word-pattern-ii/word_pattern_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem291
diff --git a/problems/word-pattern/README.md b/problems/word-pattern/README.md
deleted file mode 100644
index 9a39a81df..000000000
--- a/problems/word-pattern/README.md
+++ /dev/null
@@ -1,65 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../game-of-life "Game of Life")
-　　　　　　　　　　　　　　　　
-[Next >](../word-pattern-ii "Word Pattern II")
-
-## [290. Word Pattern (Easy)](https://leetcode.com/problems/word-pattern "单词规律")
-
-<p>Given a <code>pattern</code> and a string <code>s</code>, find if <code>s</code>&nbsp;follows the same pattern.</p>
-
-<p>Here <b>follow</b> means a full match, such that there is a bijection between a letter in <code>pattern</code> and a <b>non-empty</b> word in <code>s</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> pattern = &quot;abba&quot;, s = &quot;dog cat cat dog&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> pattern = &quot;abba&quot;, s = &quot;dog cat cat fish&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> pattern = &quot;aaaa&quot;, s = &quot;dog cat cat dog&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> pattern = &quot;abba&quot;, s = &quot;dog dog dog dog&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= pattern.length &lt;= 300</code></li>
-	<li><code>pattern</code> contains only lower-case English letters.</li>
-	<li><code>1 &lt;= s.length &lt;= 3000</code></li>
-	<li><code>s</code> contains only lower-case English letters and spaces <code>&#39; &#39;</code>.</li>
-	<li><code>s</code> <strong>does not contain</strong> any leading or trailing spaces.</li>
-	<li>All the words in <code>s</code> are separated by a <strong>single space</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
-
-### Similar Questions
-  1. [Isomorphic Strings](../isomorphic-strings) (Easy)
-  1. [Word Pattern II](../word-pattern-ii) (Medium)
diff --git a/problems/word-pattern/word_pattern.go b/problems/word-pattern/word_pattern.go
deleted file mode 100644
index 36a529d18..000000000
--- a/problems/word-pattern/word_pattern.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package problem290
-
-import "strings"
-
-func wordPattern(pattern string, str string) bool {
-	ss, l := strings.Split(str, " "), len(pattern)
-	m, e := make(map[byte]string), make(map[string]bool)
-	if len(ss) != l {
-		return false
-	}
-	for i := 0; i < l; i++ {
-		if s, ok := m[pattern[i]]; ok {
-			if ss[i] != s {
-				return false
-			}
-		} else if e[ss[i]] {
-			return false
-		} else {
-			m[pattern[i]], e[ss[i]] = ss[i], true
-		}
-	}
-	return true
-}
diff --git a/problems/word-pattern/word_pattern_test.go b/problems/word-pattern/word_pattern_test.go
deleted file mode 100644
index 4df4e38b2..000000000
--- a/problems/word-pattern/word_pattern_test.go
+++ /dev/null
@@ -1,55 +0,0 @@
-package problem290
-
-import "testing"
-
-type testType struct {
-	pattern string
-	str     string
-	want    bool
-}
-
-func TestWordPattern(t *testing.T) {
-	tests := [...]testType{
-		{
-			pattern: "abba",
-			str:     "dog cat cat dog",
-			want:    true,
-		},
-		{
-			pattern: "abba",
-			str:     "dog cat cat fish",
-			want:    false,
-		},
-		{
-			pattern: "aaaa",
-			str:     "dog cat cat dog",
-			want:    false,
-		},
-		{
-			pattern: "abba",
-			str:     "dog dog dog dog",
-			want:    false,
-		},
-		{
-			pattern: "abba",
-			str:     "dog cat cat dog fish",
-			want:    false,
-		},
-		{
-			pattern: "abba",
-			str:     "b a a b",
-			want:    true,
-		},
-		{
-			pattern: "abba",
-			str:     "b c c b",
-			want:    true,
-		},
-	}
-	for _, tt := range tests {
-		got := wordPattern(tt.pattern, tt.str)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.pattern, got, tt.want)
-		}
-	}
-}
diff --git a/problems/word-search-ii/README.md b/problems/word-search-ii/README.md
deleted file mode 100644
index 65fb04542..000000000
--- a/problems/word-search-ii/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../design-add-and-search-words-data-structure "Design Add and Search Words Data Structure")
-　　　　　　　　　　　　　　　　
-[Next >](../house-robber-ii "House Robber II")
-
-## [212. Word Search II (Hard)](https://leetcode.com/problems/word-search-ii "单词搜索 II")
-
-<p>Given an <code>m x n</code> <code>board</code>&nbsp;of characters and a list of strings <code>words</code>, return <em>all words on the board</em>.</p>
-
-<p>Each word must be constructed from letters of sequentially adjacent cells, where <strong>adjacent cells</strong> are horizontally or vertically neighboring. The same letter cell may not be used more than once in a word.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/07/search1.jpg" style="width: 322px; height: 322px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;o&quot;,&quot;a&quot;,&quot;a&quot;,&quot;n&quot;],[&quot;e&quot;,&quot;t&quot;,&quot;a&quot;,&quot;e&quot;],[&quot;i&quot;,&quot;h&quot;,&quot;k&quot;,&quot;r&quot;],[&quot;i&quot;,&quot;f&quot;,&quot;l&quot;,&quot;v&quot;]], words = [&quot;oath&quot;,&quot;pea&quot;,&quot;eat&quot;,&quot;rain&quot;]
-<strong>Output:</strong> [&quot;eat&quot;,&quot;oath&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/07/search2.jpg" style="width: 162px; height: 162px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;a&quot;,&quot;b&quot;],[&quot;c&quot;,&quot;d&quot;]], words = [&quot;abcb&quot;]
-<strong>Output:</strong> []
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == board.length</code></li>
-	<li><code>n == board[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 12</code></li>
-	<li><code>board[i][j]</code> is a lowercase English letter.</li>
-	<li><code>1 &lt;= words.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= words[i].length &lt;= 10</code></li>
-	<li><code>words[i]</code> consists of lowercase English letters.</li>
-	<li>All the strings of <code>words</code> are unique.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Word Search](../word-search) (Medium)
-  1. [Unique Paths III](../unique-paths-iii) (Hard)
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-You would need to optimize your backtracking to pass the larger test. Could you stop backtracking earlier?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-If the current candidate does not exist in all words&#39; prefix, you could stop backtracking immediately. What kind of data structure could answer such query efficiently? Does a hash table work? Why or why not? How about a Trie? If you would like to learn how to implement a basic trie, please work on this problem: <a href="https://leetcode.com/problems/implement-trie-prefix-tree/">Implement Trie (Prefix Tree)</a> first.
-</details>
diff --git a/problems/word-search-ii/word_search_ii.go b/problems/word-search-ii/word_search_ii.go
deleted file mode 100644
index ea2d31176..000000000
--- a/problems/word-search-ii/word_search_ii.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem212
diff --git a/problems/word-search-ii/word_search_ii_test.go b/problems/word-search-ii/word_search_ii_test.go
deleted file mode 100644
index ea2d31176..000000000
--- a/problems/word-search-ii/word_search_ii_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem212
diff --git a/problems/word-search/README.md b/problems/word-search/README.md
deleted file mode 100644
index 743c2ff89..000000000
--- a/problems/word-search/README.md
+++ /dev/null
@@ -1,60 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../subsets "Subsets")
-　　　　　　　　　　　　　　　　
-[Next >](../remove-duplicates-from-sorted-array-ii "Remove Duplicates from Sorted Array II")
-
-## [79. Word Search (Medium)](https://leetcode.com/problems/word-search "单词搜索")
-
-<p>Given an <code>m x n</code> grid of characters <code>board</code> and a string <code>word</code>, return <code>true</code> <em>if</em> <code>word</code> <em>exists in the grid</em>.</p>
-
-<p>The word can be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or vertically neighboring. The same letter cell may not be used more than once.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/04/word2.jpg" style="width: 322px; height: 242px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;A&quot;,&quot;B&quot;,&quot;C&quot;,&quot;E&quot;],[&quot;S&quot;,&quot;F&quot;,&quot;C&quot;,&quot;S&quot;],[&quot;A&quot;,&quot;D&quot;,&quot;E&quot;,&quot;E&quot;]], word = &quot;ABCCED&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 2:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/04/word-1.jpg" style="width: 322px; height: 242px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;A&quot;,&quot;B&quot;,&quot;C&quot;,&quot;E&quot;],[&quot;S&quot;,&quot;F&quot;,&quot;C&quot;,&quot;S&quot;],[&quot;A&quot;,&quot;D&quot;,&quot;E&quot;,&quot;E&quot;]], word = &quot;SEE&quot;
-<strong>Output:</strong> true
-</pre>
-
-<p><strong>Example 3:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/10/15/word3.jpg" style="width: 322px; height: 242px;" />
-<pre>
-<strong>Input:</strong> board = [[&quot;A&quot;,&quot;B&quot;,&quot;C&quot;,&quot;E&quot;],[&quot;S&quot;,&quot;F&quot;,&quot;C&quot;,&quot;S&quot;],[&quot;A&quot;,&quot;D&quot;,&quot;E&quot;,&quot;E&quot;]], word = &quot;ABCB&quot;
-<strong>Output:</strong> false
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>m == board.length</code></li>
-	<li><code>n = board[i].length</code></li>
-	<li><code>1 &lt;= m, n &lt;= 6</code></li>
-	<li><code>1 &lt;= word.length &lt;= 15</code></li>
-	<li><code>board</code> and <code>word</code> consists of only lowercase and uppercase English letters.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Follow up:</strong> Could you use search pruning to make your solution faster with a larger <code>board</code>?</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Matrix](../../tag/matrix/README.md)]
-
-### Similar Questions
-  1. [Word Search II](../word-search-ii) (Hard)
diff --git a/problems/word-search/word_search.go b/problems/word-search/word_search.go
deleted file mode 100644
index 36c4101f2..000000000
--- a/problems/word-search/word_search.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem79
diff --git a/problems/word-search/word_search_test.go b/problems/word-search/word_search_test.go
deleted file mode 100644
index 36c4101f2..000000000
--- a/problems/word-search/word_search_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem79
diff --git a/problems/word-squares/README.md b/problems/word-squares/README.md
deleted file mode 100644
index 49634a077..000000000
--- a/problems/word-squares/README.md
+++ /dev/null
@@ -1,91 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-repeating-character-replacement "Longest Repeating Character Replacement")
-　　　　　　　　　　　　　　　　
-[Next >](../convert-binary-search-tree-to-sorted-doubly-linked-list "Convert Binary Search Tree to Sorted Doubly Linked List")
-
-## [425. Word Squares (Hard)](https://leetcode.com/problems/word-squares "单词方块")
-
-<p>Given a set of words <b>(without duplicates)</b>, find all <a href="https://en.wikipedia.org/wiki/Word_square" target="_blank">word squares</a> you can build from them.</p>
-
-<p>A sequence of words forms a valid word square if the <i>k</i><sup>th</sup> row and column read the exact same string, where 0 &le; <i>k</i> &lt; max(numRows, numColumns).</p>
-
-<p>For example, the word sequence <code>["ball","area","lead","lady"]</code> forms a word square because each word reads the same both horizontally and vertically.</p>
-
-<pre>
-b a l l
-a r e a
-l e a d
-l a d y
-</pre>
-
-<p><b>Note:</b><br />
-<ol>
-<li>There are at least 1 and at most 1000 words.</li>
-<li>All words will have the exact same length.</li>
-<li>Word length is at least 1 and at most 5.</li>
-<li>Each word contains only lowercase English alphabet <code>a-z</code>.</li>
-</ol>
-</p>
-
-<p><b>Example 1:</b>
-<pre>
-<b>Input:</b>
-["area","lead","wall","lady","ball"]
-
-<b>Output:</b>
-[
-  [ "wall",
-    "area",
-    "lead",
-    "lady"
-  ],
-  [ "ball",
-    "area",
-    "lead",
-    "lady"
-  ]
-]
-
-<b>Explanation:</b>
-The output consists of two word squares. The order of output does not matter (just the order of words in each word square matters).
-</pre>
-</p>
-
-<p><b>Example 2:</b>
-<pre>
-<b>Input:</b>
-["abat","baba","atan","atal"]
-
-<b>Output:</b>
-[
-  [ "baba",
-    "abat",
-    "baba",
-    "atan"
-  ],
-  [ "baba",
-    "abat",
-    "baba",
-    "atal"
-  ]
-]
-
-<b>Explanation:</b>
-The output consists of two word squares. The order of output does not matter (just the order of words in each word square matters).
-</pre>
-</p>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
-  [[Trie](../../tag/trie/README.md)]
-
-### Similar Questions
-  1. [Valid Word Square](../valid-word-square) (Easy)
diff --git a/problems/word-squares/word_squares.go b/problems/word-squares/word_squares.go
deleted file mode 100644
index 9d15a1a7f..000000000
--- a/problems/word-squares/word_squares.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem425
diff --git a/problems/word-squares/word_squares_test.go b/problems/word-squares/word_squares_test.go
deleted file mode 100644
index 9d15a1a7f..000000000
--- a/problems/word-squares/word_squares_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem425
diff --git a/problems/word-subsets/README.md b/problems/word-subsets/README.md
deleted file mode 100644
index 67b953a6f..000000000
--- a/problems/word-subsets/README.md
+++ /dev/null
@@ -1,54 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../partition-array-into-disjoint-intervals "Partition Array into Disjoint Intervals")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-only-letters "Reverse Only Letters")
-
-## [916. Word Subsets (Medium)](https://leetcode.com/problems/word-subsets "单词子集")
-
-<p>You are given two string arrays <code>words1</code> and <code>words2</code>.</p>
-
-<p>A string <code>b</code> is a <strong>subset</strong> of string <code>a</code> if every letter in <code>b</code> occurs in <code>a</code> including multiplicity.</p>
-
-<ul>
-	<li>For example, <code>&quot;wrr&quot;</code> is a subset of <code>&quot;warrior&quot;</code> but is not a subset of <code>&quot;world&quot;</code>.</li>
-</ul>
-
-<p>A string <code>a</code> from <code>words1</code> is <strong>universal</strong> if for every string <code>b</code> in <code>words2</code>, <code>b</code> is a subset of <code>a</code>.</p>
-
-<p>Return an array of all the <strong>universal</strong> strings in <code>words1</code>. You may return the answer in <strong>any order</strong>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> words1 = [&quot;amazon&quot;,&quot;apple&quot;,&quot;facebook&quot;,&quot;google&quot;,&quot;leetcode&quot;], words2 = [&quot;e&quot;,&quot;o&quot;]
-<strong>Output:</strong> [&quot;facebook&quot;,&quot;google&quot;,&quot;leetcode&quot;]
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> words1 = [&quot;amazon&quot;,&quot;apple&quot;,&quot;facebook&quot;,&quot;google&quot;,&quot;leetcode&quot;], words2 = [&quot;l&quot;,&quot;e&quot;]
-<strong>Output:</strong> [&quot;apple&quot;,&quot;google&quot;,&quot;leetcode&quot;]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= words1.length, words2.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= words1[i].length, words2[i].length &lt;= 10</code></li>
-	<li><code>words1[i]</code> and <code>words2[i]</code> consist only of lowercase English letters.</li>
-	<li>All the strings of <code>words1</code> are <strong>unique</strong>.</li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[String](../../tag/string/README.md)]
diff --git a/problems/word-subsets/word_subsets.go b/problems/word-subsets/word_subsets.go
deleted file mode 100644
index 58e896cb8..000000000
--- a/problems/word-subsets/word_subsets.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem916
diff --git a/problems/word-subsets/word_subsets_test.go b/problems/word-subsets/word_subsets_test.go
deleted file mode 100644
index 58e896cb8..000000000
--- a/problems/word-subsets/word_subsets_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem916
diff --git a/problems/x-of-a-kind-in-a-deck-of-cards/README.md b/problems/x-of-a-kind-in-a-deck-of-cards/README.md
deleted file mode 100644
index 153a9b56a..000000000
--- a/problems/x-of-a-kind-in-a-deck-of-cards/README.md
+++ /dev/null
@@ -1,77 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../cat-and-mouse "Cat and Mouse")
-　　　　　　　　　　　　　　　　
-[Next >](../partition-array-into-disjoint-intervals "Partition Array into Disjoint Intervals")
-
-## [914. X of a Kind in a Deck of Cards (Easy)](https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards "卡牌分组")
-
-<p>In a deck of cards, each card has an integer written on it.</p>
-
-<p>Return <code>true</code> if and only if you can choose <code>X &gt;= 2</code> such that it is possible to split the entire deck into 1 or more groups of cards, where:</p>
-
-<ul>
-	<li>Each group has exactly <code>X</code> cards.</li>
-	<li>All the cards in each group have the same integer.</li>
-</ul>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> deck = [1,2,3,4,4,3,2,1]
-<strong>Output:</strong> true
-<strong>Explanation</strong>: Possible partition [1,1],[2,2],[3,3],[4,4].
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> deck = [1,1,1,2,2,2,3,3]
-<strong>Output:</strong> false
-<strong>Explanation</strong>: No possible partition.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> deck = [1]
-<strong>Output:</strong> false
-<strong>Explanation</strong>: No possible partition.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> deck = [1,1]
-<strong>Output:</strong> true
-<strong>Explanation</strong>: Possible partition [1,1].
-</pre>
-
-<p><strong>Example 5:</strong></p>
-
-<pre>
-<strong>Input:</strong> deck = [1,1,2,2,2,2]
-<strong>Output:</strong> true
-<strong>Explanation</strong>: Possible partition [1,1],[2,2],[2,2].
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= deck.length &lt;= 10<sup>4</sup></code></li>
-	<li><code>0 &lt;= deck[i] &lt; 10<sup>4</sup></code></li>
-</ul>
-
-### Related Topics
-  [[Array](../../tag/array/README.md)]
-  [[Hash Table](../../tag/hash-table/README.md)]
-  [[Math](../../tag/math/README.md)]
-  [[Counting](../../tag/counting/README.md)]
-  [[Number Theory](../../tag/number-theory/README.md)]
diff --git a/problems/x-of-a-kind-in-a-deck-of-cards/x_of_a_kind_in_a_deck_of_cards.go b/problems/x-of-a-kind-in-a-deck-of-cards/x_of_a_kind_in_a_deck_of_cards.go
deleted file mode 100644
index c81f89708..000000000
--- a/problems/x-of-a-kind-in-a-deck-of-cards/x_of_a_kind_in_a_deck_of_cards.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem914
-
-func hasGroupsSizeX(deck []int) bool {
-	m, l := make(map[int]int), len(deck)
-	for _, v := range deck {
-		m[v]++
-	}
-flag:
-	for x := 2; x <= l; x++ {
-		if l%x == 0 {
-			for _, v := range m {
-				if v%x != 0 {
-					continue flag
-				}
-			}
-			return true
-		}
-	}
-	return false
-}
diff --git a/problems/x-of-a-kind-in-a-deck-of-cards/x_of_a_kind_in_a_deck_of_cards_test.go b/problems/x-of-a-kind-in-a-deck-of-cards/x_of_a_kind_in_a_deck_of_cards_test.go
deleted file mode 100644
index ef2ea13d4..000000000
--- a/problems/x-of-a-kind-in-a-deck-of-cards/x_of_a_kind_in_a_deck_of_cards_test.go
+++ /dev/null
@@ -1,39 +0,0 @@
-package problem914
-
-import "testing"
-
-type testType struct {
-	in   []int
-	want bool
-}
-
-func TestHasGroupsSizeX(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:   []int{1, 2, 3, 4, 4, 3, 2, 1},
-			want: true,
-		},
-		{
-			in:   []int{1, 1, 1, 2, 2, 2, 3, 3},
-			want: false,
-		},
-		{
-			in:   []int{1},
-			want: false,
-		},
-		{
-			in:   []int{1, 1},
-			want: true,
-		},
-		{
-			in:   []int{1, 1, 2, 2, 2, 2},
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		got := hasGroupsSizeX(tt.in)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/xor-operation-in-an-array/README.md b/problems/xor-operation-in-an-array/README.md
deleted file mode 100644
index 89580d8aa..000000000
--- a/problems/xor-operation-in-an-array/README.md
+++ /dev/null
@@ -1,55 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../clone-binary-tree-with-random-pointer "Clone Binary Tree With Random Pointer")
-　　　　　　　　　　　　　　　　
-[Next >](../making-file-names-unique "Making File Names Unique")
-
-## [1486. XOR Operation in an Array (Easy)](https://leetcode.com/problems/xor-operation-in-an-array "数组异或操作")
-
-<p>You are given an integer <code>n</code> and an integer <code>start</code>.</p>
-
-<p>Define an array <code>nums</code> where <code>nums[i] = start + 2 * i</code> (<strong>0-indexed</strong>) and <code>n == nums.length</code>.</p>
-
-<p>Return <em>the bitwise XOR of all elements of</em> <code>nums</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 5, start = 0
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> Array nums is equal to [0, 2, 4, 6, 8] where (0 ^ 2 ^ 4 ^ 6 ^ 8) = 8.
-Where &quot;^&quot; corresponds to bitwise XOR operator.
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> n = 4, start = 3
-<strong>Output:</strong> 8
-<strong>Explanation:</strong> Array nums is equal to [3, 5, 7, 9] where (3 ^ 5 ^ 7 ^ 9) = 8.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= n &lt;= 1000</code></li>
-	<li><code>0 &lt;= start &lt;= 1000</code></li>
-	<li><code>n == nums.length</code></li>
-</ul>
-
-### Related Topics
-  [[Math](../../tag/math/README.md)]
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-Simulate the process, create an array nums and return the Bitwise XOR of all elements of it.
-</details>
diff --git a/problems/xor-queries-of-a-subarray/README.md b/problems/xor-queries-of-a-subarray/README.md
deleted file mode 100644
index 86c7462b0..000000000
--- a/problems/xor-queries-of-a-subarray/README.md
+++ /dev/null
@@ -1,75 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../decrypt-string-from-alphabet-to-integer-mapping "Decrypt String from Alphabet to Integer Mapping")
-　　　　　　　　　　　　　　　　
-[Next >](../get-watched-videos-by-your-friends "Get Watched Videos by Your Friends")
-
-## [1310. XOR Queries of a Subarray (Medium)](https://leetcode.com/problems/xor-queries-of-a-subarray "子数组异或查询")
-
-<p>You are given an array <code>arr</code> of positive integers. You are also given the array <code>queries</code> where <code>queries[i] = [left<sub>i, </sub>right<sub>i</sub>]</code>.</p>
-
-<p>For each query <code>i</code> compute the <strong>XOR</strong> of elements from <code>left<sub>i</sub></code> to <code>right<sub>i</sub></code> (that is, <code>arr[left<sub>i</sub>] XOR arr[left<sub>i</sub> + 1] XOR ... XOR arr[right<sub>i</sub>]</code> ).</p>
-
-<p>Return an array <code>answer</code> where <code>answer[i]</code> is the answer to the <code>i<sup>th</sup></code> query.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [1,3,4,8], queries = [[0,1],[1,2],[0,3],[3,3]]
-<strong>Output:</strong> [2,7,14,8] 
-<strong>Explanation:</strong> 
-The binary representation of the elements in the array are:
-1 = 0001 
-3 = 0011 
-4 = 0100 
-8 = 1000 
-The XOR values for queries are:
-[0,1] = 1 xor 3 = 2 
-[1,2] = 3 xor 4 = 7 
-[0,3] = 1 xor 3 xor 4 xor 8 = 14 
-[3,3] = 8
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> arr = [4,8,2,10], queries = [[2,3],[1,3],[0,0],[0,3]]
-<strong>Output:</strong> [8,0,4,4]
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= arr.length, queries.length &lt;= 3 * 10<sup>4</sup></code></li>
-	<li><code>1 &lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
-	<li><code>queries[i].length == 2</code></li>
-	<li><code>0 &lt;= left<sub>i</sub> &lt;= right<sub>i</sub> &lt; arr.length</code></li>
-</ul>
-
-### Related Topics
-  [[Bit Manipulation](../../tag/bit-manipulation/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Prefix Sum](../../tag/prefix-sum/README.md)]
-
-### Hints
-<details>
-<summary>Hint 1</summary>
-What is the result of x ^ y ^ x ?
-</details>
-
-<details>
-<summary>Hint 2</summary>
-Compute the prefix sum for XOR.
-</details>
-
-<details>
-<summary>Hint 3</summary>
-Process the queries with the prefix sum values.
-</details>
diff --git a/problems/zigzag-conversion/README.md b/problems/zigzag-conversion/README.md
deleted file mode 100644
index 2307a86c4..000000000
--- a/problems/zigzag-conversion/README.md
+++ /dev/null
@@ -1,67 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../longest-palindromic-substring "Longest Palindromic Substring")
-　　　　　　　　　　　　　　　　
-[Next >](../reverse-integer "Reverse Integer")
-
-## [6. Zigzag Conversion (Medium)](https://leetcode.com/problems/zigzag-conversion "Z 字形变换")
-
-<p>The string <code>&quot;PAYPALISHIRING&quot;</code> is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)</p>
-
-<pre>
-P   A   H   N
-A P L S I I G
-Y   I   R
-</pre>
-
-<p>And then read line by line: <code>&quot;PAHNAPLSIIGYIR&quot;</code></p>
-
-<p>Write the code that will take a string and make this conversion given a number of rows:</p>
-
-<pre>
-string convert(string s, int numRows);
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;PAYPALISHIRING&quot;, numRows = 3
-<strong>Output:</strong> &quot;PAHNAPLSIIGYIR&quot;
-</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;PAYPALISHIRING&quot;, numRows = 4
-<strong>Output:</strong> &quot;PINALSIGYAHRPI&quot;
-<strong>Explanation:</strong>
-P     I    N
-A   L S  I G
-Y A   H R
-P     I
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> s = &quot;A&quot;, numRows = 1
-<strong>Output:</strong> &quot;A&quot;
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
-	<li><code>s</code> consists of English letters (lower-case and upper-case), <code>&#39;,&#39;</code> and <code>&#39;.&#39;</code>.</li>
-	<li><code>1 &lt;= numRows &lt;= 1000</code></li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
diff --git a/problems/zigzag-conversion/zigzag_conversion.go b/problems/zigzag-conversion/zigzag_conversion.go
deleted file mode 100644
index 9df2bdd1c..000000000
--- a/problems/zigzag-conversion/zigzag_conversion.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package problem6
-
-func convert(s string, numRows int) string {
-	l := len(s)
-	if l <= numRows || numRows < 2 {
-		return s
-	}
-	ans, col := make([]byte, 0, l), (l-1)/(numRows-1)
-	for r := 0; r < numRows; r++ {
-		for c := 0; c <= col; c++ {
-			if c&1 == 0 || r > 0 && r < numRows-1 {
-				k := (numRows-1)*(c+c&1) + r*(1-c&1*2)
-				if k < l {
-					ans = append(ans, s[k])
-				}
-			}
-		}
-	}
-	return string(ans)
-}
diff --git a/problems/zigzag-conversion/zigzag_conversion_test.go b/problems/zigzag-conversion/zigzag_conversion_test.go
deleted file mode 100644
index b23fa2c22..000000000
--- a/problems/zigzag-conversion/zigzag_conversion_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package problem6
-
-import "testing"
-
-type testType struct {
-	in      string
-	numRows int
-	want    string
-}
-
-func TestConvert(t *testing.T) {
-	tests := [...]testType{
-		{
-			in:      "PAYPALISHIRING",
-			numRows: 3,
-			want:    "PAHNAPLSIIGYIR",
-		},
-		{
-			in:      "PAYPALISHIRING",
-			numRows: 4,
-			want:    "PINALSIGYAHRPI",
-		},
-		{
-			in:      "AB",
-			numRows: 1,
-			want:    "AB",
-		},
-	}
-	for _, tt := range tests {
-		got := convert(tt.in, tt.numRows)
-		if got != tt.want {
-			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
-		}
-	}
-}
diff --git a/problems/zigzag-iterator/README.md b/problems/zigzag-iterator/README.md
deleted file mode 100644
index 9c3ae3609..000000000
--- a/problems/zigzag-iterator/README.md
+++ /dev/null
@@ -1,52 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../wiggle-sort "Wiggle Sort")
-　　　　　　　　　　　　　　　　
-[Next >](../expression-add-operators "Expression Add Operators")
-
-## [281. Zigzag Iterator (Medium)](https://leetcode.com/problems/zigzag-iterator "锯齿迭代器")
-
-<p>Given two 1d vectors, implement an iterator to return their elements alternately.</p>
-
-<p><strong>Example:</strong></p>
-
-<pre>
-<strong>Input:</strong>
-v1 = [1,2]
-v2 = [3,4,5,6] 
-
-<strong>Output:</strong> <code>[1,3,2,4,5,6]
-
-<strong>Explanation:</strong></code>&nbsp;By calling <i>next</i> repeatedly until <i>hasNext</i> returns <code>false</code>, 
-&nbsp;            the order of elements returned by <i>next</i> should be: <code>[1,3,2,4,5,6]</code>.</pre>
-
-<p><b>Follow up</b>: What if you are given <code>k</code> 1d vectors? How well can your code be extended to such cases?</p>
-
-<p><strong>Clarification </strong><b>for the follow up question</b><strong>:</strong><br />
-The &quot;Zigzag&quot; order is not clearly defined and is ambiguous for <code>k &gt; 2</code> cases. If &quot;Zigzag&quot; does not look right to you, replace &quot;Zigzag&quot; with &quot;Cyclic&quot;. For example:</p>
-
-<pre>
-<strong>Input:</strong>
-[1,2,3]
-[4,5,6,7]
-[8,9]
-
-<strong>Output: </strong><code>[1,4,8,2,5,9,3,6,7]</code>.
-</pre>
-
-### Related Topics
-  [[Design](../../tag/design/README.md)]
-  [[Queue](../../tag/queue/README.md)]
-  [[Array](../../tag/array/README.md)]
-  [[Iterator](../../tag/iterator/README.md)]
-
-### Similar Questions
-  1. [Binary Search Tree Iterator](../binary-search-tree-iterator) (Medium)
-  1. [Flatten 2D Vector](../flatten-2d-vector) (Medium)
-  1. [Peeking Iterator](../peeking-iterator) (Medium)
-  1. [Flatten Nested List Iterator](../flatten-nested-list-iterator) (Medium)
diff --git a/problems/zigzag-iterator/zigzag_iterator.go b/problems/zigzag-iterator/zigzag_iterator.go
deleted file mode 100644
index 05b4eff34..000000000
--- a/problems/zigzag-iterator/zigzag_iterator.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem281
diff --git a/problems/zigzag-iterator/zigzag_iterator_test.go b/problems/zigzag-iterator/zigzag_iterator_test.go
deleted file mode 100644
index 05b4eff34..000000000
--- a/problems/zigzag-iterator/zigzag_iterator_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem281
diff --git a/problems/zuma-game/README.md b/problems/zuma-game/README.md
deleted file mode 100644
index d05daca25..000000000
--- a/problems/zuma-game/README.md
+++ /dev/null
@@ -1,90 +0,0 @@
-<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-[< Previous](../max-consecutive-ones-ii "Max Consecutive Ones II")
-　　　　　　　　　　　　　　　　
-[Next >](../robot-room-cleaner "Robot Room Cleaner")
-
-## [488. Zuma Game (Hard)](https://leetcode.com/problems/zuma-game "祖玛游戏")
-
-<p>You are playing a variation of the game Zuma.</p>
-
-<p>In this variation of Zuma, there is a <strong>single row</strong> of colored balls on a board, where each ball can be colored red <code>&#39;R&#39;</code>, yellow <code>&#39;Y&#39;</code>, blue <code>&#39;B&#39;</code>, green <code>&#39;G&#39;</code>, or white <code>&#39;W&#39;</code>. You also have several colored balls in your hand.</p>
-
-<p>Your goal is to <strong>clear all</strong> of the balls from the board. On each turn:</p>
-
-<ul>
-	<li>Pick <strong>any</strong> ball from your hand and insert it in between two balls in the row or on either end of the row.</li>
-	<li>If there is a group of <strong>three or more consecutive balls</strong> of the <strong>same color</strong>, remove the group of balls from the board.
-	<ul>
-		<li>If this removal causes more groups of three or more of the same color to form, then continue removing each group until there are none left.</li>
-	</ul>
-	</li>
-	<li>If there are no more balls on the board, then you win the game.</li>
-	<li>Repeat this process until you either win or do not have any more balls in your hand.</li>
-</ul>
-
-<p>Given a string <code>board</code>, representing the row of balls on the board, and a string <code>hand</code>, representing the balls in your hand, return <em>the <strong>minimum</strong> number of balls you have to insert to clear all the balls from the board. If you cannot clear all the balls from the board using the balls in your hand, return </em><code>-1</code>.</p>
-
-<p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
-
-<pre>
-<strong>Input:</strong> board = &quot;WRRBBW&quot;, hand = &quot;RB&quot;
-<strong>Output:</strong> -1
-<strong>Explanation:</strong> It is impossible to clear all the balls. The best you can do is:
-- Insert &#39;R&#39; so the board becomes WRR<u>R</u>BBW. W<u>RRR</u>BBW -&gt; WBBW.
-- Insert &#39;B&#39; so the board becomes WBB<u>B</u>W. W<u>BBB</u>W -&gt; WW.
-There are still balls remaining on the board, and you are out of balls to insert.</pre>
-
-<p><strong>Example 2:</strong></p>
-
-<pre>
-<strong>Input:</strong> board = &quot;WWRRBBWW&quot;, hand = &quot;WRBRW&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> To make the board empty:
-- Insert &#39;R&#39; so the board becomes WWRR<u>R</u>BBWW. WW<u>RRR</u>BBWW -&gt; WWBBWW.
-- Insert &#39;B&#39; so the board becomes WWBB<u>B</u>WW. WW<u>BBB</u>WW -&gt; <u>WWWW</u> -&gt; empty.
-2 balls from your hand were needed to clear the board.
-</pre>
-
-<p><strong>Example 3:</strong></p>
-
-<pre>
-<strong>Input:</strong> board = &quot;G&quot;, hand = &quot;GGGGG&quot;
-<strong>Output:</strong> 2
-<strong>Explanation:</strong> To make the board empty:
-- Insert &#39;G&#39; so the board becomes G<u>G</u>.
-- Insert &#39;G&#39; so the board becomes GG<u>G</u>. <u>GGG</u> -&gt; empty.
-2 balls from your hand were needed to clear the board.
-</pre>
-
-<p><strong>Example 4:</strong></p>
-
-<pre>
-<strong>Input:</strong> board = &quot;RBYYBBRRB&quot;, hand = &quot;YRBGB&quot;
-<strong>Output:</strong> 3
-<strong>Explanation:</strong> To make the board empty:
-- Insert &#39;Y&#39; so the board becomes RBYY<u>Y</u>BBRRB. RB<u>YYY</u>BBRRB -&gt; R<u>BBB</u>RRB -&gt; <u>RRR</u>B -&gt; B.
-- Insert &#39;B&#39; so the board becomes B<u>B</u>.
-- Insert &#39;B&#39; so the board becomes BB<u>B</u>. <u>BBB</u> -&gt; empty.
-3 balls from your hand were needed to clear the board.
-</pre>
-
-<p>&nbsp;</p>
-<p><strong>Constraints:</strong></p>
-
-<ul>
-	<li><code>1 &lt;= board.length &lt;= 16</code></li>
-	<li><code>1 &lt;= hand.length &lt;= 5</code></li>
-	<li><code>board</code> and <code>hand</code> consist of the characters <code>&#39;R&#39;</code>, <code>&#39;Y&#39;</code>, <code>&#39;B&#39;</code>, <code>&#39;G&#39;</code>, and <code>&#39;W&#39;</code>.</li>
-	<li>The initial row of balls on the board will <strong>not</strong> have any groups of three or more consecutive balls of the same color.</li>
-</ul>
-
-### Related Topics
-  [[String](../../tag/string/README.md)]
-  [[Backtracking](../../tag/backtracking/README.md)]
diff --git a/problems/zuma-game/zuma_game.go b/problems/zuma-game/zuma_game.go
deleted file mode 100644
index 6202ce734..000000000
--- a/problems/zuma-game/zuma_game.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem488
diff --git a/problems/zuma-game/zuma_game_test.go b/problems/zuma-game/zuma_game_test.go
deleted file mode 100644
index 6202ce734..000000000
--- a/problems/zuma-game/zuma_game_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package problem488
diff --git a/readme/1-300.md b/readme/1-300.md
deleted file mode 100644
index 4bb184fe2..000000000
--- a/readme/1-300.md
+++ /dev/null
@@ -1,388 +0,0 @@
-<!--|This file generated by command(leetcode readme); DO NOT EDIT.         |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-# [LeetCode](https://awesee.github.io/leetcode)
-LeetCode Problems' Solutions
-[[力扣](https://awesee.github.io/categories/leetcode/) ∙ [话题分类](https://github.com/awesee/leetcode/blob/master/tag/README.md)]
-
-[![Go](https://github.com/awesee/leetcode/workflows/Go/badge.svg)](https://github.com/awesee/leetcode/actions)
-[![codecov](https://codecov.io/gh/awesee/leetcode/branch/master/graph/badge.svg)](https://codecov.io/gh/awesee/leetcode)
-[![Go Report Card](https://goreportcard.com/badge/github.com/awesee/leetcode)](https://goreportcard.com/report/github.com/awesee/leetcode)
-[![GitHub contributors](https://img.shields.io/github/contributors/awesee/leetcode.svg)](https://github.com/awesee/leetcode/graphs/contributors)
-[![license](https://img.shields.io/github/license/awesee/leetcode.svg)](https://github.com/awesee/leetcode/blob/master/LICENSE)
-[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fawesee%2Fleetcode.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fawesee%2Fleetcode?ref=badge_shield)
-[![Join the chat](https://badges.gitter.im/awesee/leetcode.svg)](https://gitter.im/awesee/leetcode?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-
-<table><thead>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#1">[1-50]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#51">[51-100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#101">[101-150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#151">[151-200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#201">[201-250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#251">[251-300]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#301">[301-350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#351">[351-400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#401">[401-450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#451">[451-500]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#501">[501-550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#551">[551-600]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#601">[601-650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#651">[651-700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#701">[701-750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#751">[751-800]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#801">[801-850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#851">[851-900]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#901">[901-950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#951">[951-1000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1001">[1001-1050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1051">[1051-1100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1101">[1101-1150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1151">[1151-1200]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1201">[1201-1250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1251">[1251-1300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1301">[1301-1350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1351">[1351-1400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1401">[1401-1450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1451">[1451-1500]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1501">[1501-1550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1551">[1551-1600]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1601">[1601-1650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1651">[1651-1700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1701">[1701-1750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1751">[1751-1800]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1850">[1801-1850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1900">[1851-1900]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1950">[1901-1950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2000">[1951-2000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2050">[2001-2050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2100">[2051-2100]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2150">[2101-2150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2200">[2151-2200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2250">[2201-2250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2300">[2251-2300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2350">[2301-2350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2400">[2351-2400]</a></th>
-</tr>
-</thead></table>
-
-| # | Title | Solution | Difficulty |
-| :-: | - | - | :-: |
-| <span id="1">1</span> | [Two Sum](https://leetcode.com/problems/two-sum "两数之和") | [Go](../problems/two-sum) | Easy |
-| <span id="2">2</span> | [Add Two Numbers](https://leetcode.com/problems/add-two-numbers "两数相加") | [Go](../problems/add-two-numbers) | Medium |
-| <span id="3">3</span> | [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters "无重复字符的最长子串") | [Go](../problems/longest-substring-without-repeating-characters) | Medium |
-| <span id="4">4</span> | [Median of Two Sorted Arrays](https://leetcode.com/problems/median-of-two-sorted-arrays "寻找两个正序数组的中位数") | [Go](../problems/median-of-two-sorted-arrays) | Hard |
-| <span id="5">5</span> | [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring "最长回文子串") | [Go](../problems/longest-palindromic-substring) | Medium |
-| <span id="6">6</span> | [Zigzag Conversion](https://leetcode.com/problems/zigzag-conversion "Z 字形变换") | [Go](../problems/zigzag-conversion) | Medium |
-| <span id="7">7</span> | [Reverse Integer](https://leetcode.com/problems/reverse-integer "整数反转") | [Go](../problems/reverse-integer) | Medium |
-| <span id="8">8</span> | [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi "字符串转换整数 (atoi)") | [Go](../problems/string-to-integer-atoi) | Medium |
-| <span id="9">9</span> | [Palindrome Number](https://leetcode.com/problems/palindrome-number "回文数") | [Go](../problems/palindrome-number) | Easy |
-| <span id="10">10</span> | [Regular Expression Matching](https://leetcode.com/problems/regular-expression-matching "正则表达式匹配") | [Go](../problems/regular-expression-matching) | Hard |
-| <span id="11">11</span> | [Container With Most Water](https://leetcode.com/problems/container-with-most-water "盛最多水的容器") | [Go](../problems/container-with-most-water) | Medium |
-| <span id="12">12</span> | [Integer to Roman](https://leetcode.com/problems/integer-to-roman "整数转罗马数字") | [Go](../problems/integer-to-roman) | Medium |
-| <span id="13">13</span> | [Roman to Integer](https://leetcode.com/problems/roman-to-integer "罗马数字转整数") | [Go](../problems/roman-to-integer) | Easy |
-| <span id="14">14</span> | [Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix "最长公共前缀") | [Go](../problems/longest-common-prefix) | Easy |
-| <span id="15">15</span> | [3Sum](https://leetcode.com/problems/3sum "三数之和") | [Go](../problems/3sum) | Medium |
-| <span id="16">16</span> | [3Sum Closest](https://leetcode.com/problems/3sum-closest "最接近的三数之和") | [Go](../problems/3sum-closest) | Medium |
-| <span id="17">17</span> | [Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number "电话号码的字母组合") | [Go](../problems/letter-combinations-of-a-phone-number) | Medium |
-| <span id="18">18</span> | [4Sum](https://leetcode.com/problems/4sum "四数之和") | [Go](../problems/4sum) | Medium |
-| <span id="19">19</span> | [Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list "删除链表的倒数第 N 个结点") | [Go](../problems/remove-nth-node-from-end-of-list) | Medium |
-| <span id="20">20</span> | [Valid Parentheses](https://leetcode.com/problems/valid-parentheses "有效的括号") | [Go](../problems/valid-parentheses) | Easy |
-| <span id="21">21</span> | [Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists "合并两个有序链表") | [Go](../problems/merge-two-sorted-lists) | Easy |
-| <span id="22">22</span> | [Generate Parentheses](https://leetcode.com/problems/generate-parentheses "括号生成") | [Go](../problems/generate-parentheses) | Medium |
-| <span id="23">23</span> | [Merge k Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists "合并K个升序链表") | [Go](../problems/merge-k-sorted-lists) | Hard |
-| <span id="24">24</span> | [Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs "两两交换链表中的节点") | [Go](../problems/swap-nodes-in-pairs) | Medium |
-| <span id="25">25</span> | [Reverse Nodes in k-Group](https://leetcode.com/problems/reverse-nodes-in-k-group "K 个一组翻转链表") | [Go](../problems/reverse-nodes-in-k-group) | Hard |
-| <span id="26">26</span> | [Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array "删除有序数组中的重复项") | [Go](../problems/remove-duplicates-from-sorted-array) | Easy |
-| <span id="27">27</span> | [Remove Element](https://leetcode.com/problems/remove-element "移除元素") | [Go](../problems/remove-element) | Easy |
-| <span id="28">28</span> | [Implement strStr()](https://leetcode.com/problems/implement-strstr "实现 strStr()") | [Go](../problems/implement-strstr) | Easy |
-| <span id="29">29</span> | [Divide Two Integers](https://leetcode.com/problems/divide-two-integers "两数相除") | [Go](../problems/divide-two-integers) | Medium |
-| <span id="30">30</span> | [Substring with Concatenation of All Words](https://leetcode.com/problems/substring-with-concatenation-of-all-words "串联所有单词的子串") | [Go](../problems/substring-with-concatenation-of-all-words) | Hard |
-| <span id="31">31</span> | [Next Permutation](https://leetcode.com/problems/next-permutation "下一个排列") | [Go](../problems/next-permutation) | Medium |
-| <span id="32">32</span> | [Longest Valid Parentheses](https://leetcode.com/problems/longest-valid-parentheses "最长有效括号") | [Go](../problems/longest-valid-parentheses) | Hard |
-| <span id="33">33</span> | [Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array "搜索旋转排序数组") | [Go](../problems/search-in-rotated-sorted-array) | Medium |
-| <span id="34">34</span> | [Find First and Last Position of Element in Sorted Array](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array "在排序数组中查找元素的第一个和最后一个位置") | [Go](../problems/find-first-and-last-position-of-element-in-sorted-array) | Medium |
-| <span id="35">35</span> | [Search Insert Position](https://leetcode.com/problems/search-insert-position "搜索插入位置") | [Go](../problems/search-insert-position) | Easy |
-| <span id="36">36</span> | [Valid Sudoku](https://leetcode.com/problems/valid-sudoku "有效的数独") | [Go](../problems/valid-sudoku) | Medium |
-| <span id="37">37</span> | [Sudoku Solver](https://leetcode.com/problems/sudoku-solver "解数独") | [Go](../problems/sudoku-solver) | Hard |
-| <span id="38">38</span> | [Count and Say](https://leetcode.com/problems/count-and-say "外观数列") | [Go](../problems/count-and-say) | Medium |
-| <span id="39">39</span> | [Combination Sum](https://leetcode.com/problems/combination-sum "组合总和") | [Go](../problems/combination-sum) | Medium |
-| <span id="40">40</span> | [Combination Sum II](https://leetcode.com/problems/combination-sum-ii "组合总和 II") | [Go](../problems/combination-sum-ii) | Medium |
-| <span id="41">41</span> | [First Missing Positive](https://leetcode.com/problems/first-missing-positive "缺失的第一个正数") | [Go](../problems/first-missing-positive) | Hard |
-| <span id="42">42</span> | [Trapping Rain Water](https://leetcode.com/problems/trapping-rain-water "接雨水") | [Go](../problems/trapping-rain-water) | Hard |
-| <span id="43">43</span> | [Multiply Strings](https://leetcode.com/problems/multiply-strings "字符串相乘") | [Go](../problems/multiply-strings) | Medium |
-| <span id="44">44</span> | [Wildcard Matching](https://leetcode.com/problems/wildcard-matching "通配符匹配") | [Go](../problems/wildcard-matching) | Hard |
-| <span id="45">45</span> | [Jump Game II](https://leetcode.com/problems/jump-game-ii "跳跃游戏 II") | [Go](../problems/jump-game-ii) | Medium |
-| <span id="46">46</span> | [Permutations](https://leetcode.com/problems/permutations "全排列") | [Go](../problems/permutations) | Medium |
-| <span id="47">47</span> | [Permutations II](https://leetcode.com/problems/permutations-ii "全排列 II") | [Go](../problems/permutations-ii) | Medium |
-| <span id="48">48</span> | [Rotate Image](https://leetcode.com/problems/rotate-image "旋转图像") | [Go](../problems/rotate-image) | Medium |
-| <span id="49">49</span> | [Group Anagrams](https://leetcode.com/problems/group-anagrams "字母异位词分组") | [Go](../problems/group-anagrams) | Medium |
-| <span id="50">50</span> | [Pow(x, n)](https://leetcode.com/problems/powx-n "Pow(x, n)") | [Go](../problems/powx-n) | Medium |
-| <span id="51">51</span> | [N-Queens](https://leetcode.com/problems/n-queens "N 皇后") | [Go](../problems/n-queens) | Hard |
-| <span id="52">52</span> | [N-Queens II](https://leetcode.com/problems/n-queens-ii "N皇后 II") | [Go](../problems/n-queens-ii) | Hard |
-| <span id="53">53</span> | [Maximum Subarray](https://leetcode.com/problems/maximum-subarray "最大子数组和") | [Go](../problems/maximum-subarray) | Easy |
-| <span id="54">54</span> | [Spiral Matrix](https://leetcode.com/problems/spiral-matrix "螺旋矩阵") | [Go](../problems/spiral-matrix) | Medium |
-| <span id="55">55</span> | [Jump Game](https://leetcode.com/problems/jump-game "跳跃游戏") | [Go](../problems/jump-game) | Medium |
-| <span id="56">56</span> | [Merge Intervals](https://leetcode.com/problems/merge-intervals "合并区间") | [Go](../problems/merge-intervals) | Medium |
-| <span id="57">57</span> | [Insert Interval](https://leetcode.com/problems/insert-interval "插入区间") | [Go](../problems/insert-interval) | Medium |
-| <span id="58">58</span> | [Length of Last Word](https://leetcode.com/problems/length-of-last-word "最后一个单词的长度") | [Go](../problems/length-of-last-word) | Easy |
-| <span id="59">59</span> | [Spiral Matrix II](https://leetcode.com/problems/spiral-matrix-ii "螺旋矩阵 II") | [Go](../problems/spiral-matrix-ii) | Medium |
-| <span id="60">60</span> | [Permutation Sequence](https://leetcode.com/problems/permutation-sequence "排列序列") | [Go](../problems/permutation-sequence) | Hard |
-| <span id="61">61</span> | [Rotate List](https://leetcode.com/problems/rotate-list "旋转链表") | [Go](../problems/rotate-list) | Medium |
-| <span id="62">62</span> | [Unique Paths](https://leetcode.com/problems/unique-paths "不同路径") | [Go](../problems/unique-paths) | Medium |
-| <span id="63">63</span> | [Unique Paths II](https://leetcode.com/problems/unique-paths-ii "不同路径 II") | [Go](../problems/unique-paths-ii) | Medium |
-| <span id="64">64</span> | [Minimum Path Sum](https://leetcode.com/problems/minimum-path-sum "最小路径和") | [Go](../problems/minimum-path-sum) | Medium |
-| <span id="65">65</span> | [Valid Number](https://leetcode.com/problems/valid-number "有效数字") | [Go](../problems/valid-number) | Hard |
-| <span id="66">66</span> | [Plus One](https://leetcode.com/problems/plus-one "加一") | [Go](../problems/plus-one) | Easy |
-| <span id="67">67</span> | [Add Binary](https://leetcode.com/problems/add-binary "二进制求和") | [Go](../problems/add-binary) | Easy |
-| <span id="68">68</span> | [Text Justification](https://leetcode.com/problems/text-justification "文本左右对齐") | [Go](../problems/text-justification) | Hard |
-| <span id="69">69</span> | [Sqrt(x)](https://leetcode.com/problems/sqrtx "x 的平方根 ") | [Go](../problems/sqrtx) | Easy |
-| <span id="70">70</span> | [Climbing Stairs](https://leetcode.com/problems/climbing-stairs "爬楼梯") | [Go](../problems/climbing-stairs) | Easy |
-| <span id="71">71</span> | [Simplify Path](https://leetcode.com/problems/simplify-path "简化路径") | [Go](../problems/simplify-path) | Medium |
-| <span id="72">72</span> | [Edit Distance](https://leetcode.com/problems/edit-distance "编辑距离") | [Go](../problems/edit-distance) | Hard |
-| <span id="73">73</span> | [Set Matrix Zeroes](https://leetcode.com/problems/set-matrix-zeroes "矩阵置零") | [Go](../problems/set-matrix-zeroes) | Medium |
-| <span id="74">74</span> | [Search a 2D Matrix](https://leetcode.com/problems/search-a-2d-matrix "搜索二维矩阵") | [Go](../problems/search-a-2d-matrix) | Medium |
-| <span id="75">75</span> | [Sort Colors](https://leetcode.com/problems/sort-colors "颜色分类") | [Go](../problems/sort-colors) | Medium |
-| <span id="76">76</span> | [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring "最小覆盖子串") | [Go](../problems/minimum-window-substring) | Hard |
-| <span id="77">77</span> | [Combinations](https://leetcode.com/problems/combinations "组合") | [Go](../problems/combinations) | Medium |
-| <span id="78">78</span> | [Subsets](https://leetcode.com/problems/subsets "子集") | [Go](../problems/subsets) | Medium |
-| <span id="79">79</span> | [Word Search](https://leetcode.com/problems/word-search "单词搜索") | [Go](../problems/word-search) | Medium |
-| <span id="80">80</span> | [Remove Duplicates from Sorted Array II](https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii "删除有序数组中的重复项 II") | [Go](../problems/remove-duplicates-from-sorted-array-ii) | Medium |
-| <span id="81">81</span> | [Search in Rotated Sorted Array II](https://leetcode.com/problems/search-in-rotated-sorted-array-ii "搜索旋转排序数组 II") | [Go](../problems/search-in-rotated-sorted-array-ii) | Medium |
-| <span id="82">82</span> | [Remove Duplicates from Sorted List II](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii "删除排序链表中的重复元素 II") | [Go](../problems/remove-duplicates-from-sorted-list-ii) | Medium |
-| <span id="83">83</span> | [Remove Duplicates from Sorted List](https://leetcode.com/problems/remove-duplicates-from-sorted-list "删除排序链表中的重复元素") | [Go](../problems/remove-duplicates-from-sorted-list) | Easy |
-| <span id="84">84</span> | [Largest Rectangle in Histogram](https://leetcode.com/problems/largest-rectangle-in-histogram "柱状图中最大的矩形") | [Go](../problems/largest-rectangle-in-histogram) | Hard |
-| <span id="85">85</span> | [Maximal Rectangle](https://leetcode.com/problems/maximal-rectangle "最大矩形") | [Go](../problems/maximal-rectangle) | Hard |
-| <span id="86">86</span> | [Partition List](https://leetcode.com/problems/partition-list "分隔链表") | [Go](../problems/partition-list) | Medium |
-| <span id="87">87</span> | [Scramble String](https://leetcode.com/problems/scramble-string "扰乱字符串") | [Go](../problems/scramble-string) | Hard |
-| <span id="88">88</span> | [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array "合并两个有序数组") | [Go](../problems/merge-sorted-array) | Easy |
-| <span id="89">89</span> | [Gray Code](https://leetcode.com/problems/gray-code "格雷编码") | [Go](../problems/gray-code) | Medium |
-| <span id="90">90</span> | [Subsets II](https://leetcode.com/problems/subsets-ii "子集 II") | [Go](../problems/subsets-ii) | Medium |
-| <span id="91">91</span> | [Decode Ways](https://leetcode.com/problems/decode-ways "解码方法") | [Go](../problems/decode-ways) | Medium |
-| <span id="92">92</span> | [Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii "反转链表 II") | [Go](../problems/reverse-linked-list-ii) | Medium |
-| <span id="93">93</span> | [Restore IP Addresses](https://leetcode.com/problems/restore-ip-addresses "复原 IP 地址") | [Go](../problems/restore-ip-addresses) | Medium |
-| <span id="94">94</span> | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal "二叉树的中序遍历") | [Go](../problems/binary-tree-inorder-traversal) | Easy |
-| <span id="95">95</span> | [Unique Binary Search Trees II](https://leetcode.com/problems/unique-binary-search-trees-ii "不同的二叉搜索树 II") | [Go](../problems/unique-binary-search-trees-ii) | Medium |
-| <span id="96">96</span> | [Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees "不同的二叉搜索树") | [Go](../problems/unique-binary-search-trees) | Medium |
-| <span id="97">97</span> | [Interleaving String](https://leetcode.com/problems/interleaving-string "交错字符串") | [Go](../problems/interleaving-string) | Medium |
-| <span id="98">98</span> | [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree "验证二叉搜索树") | [Go](../problems/validate-binary-search-tree) | Medium |
-| <span id="99">99</span> | [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree "恢复二叉搜索树") | [Go](../problems/recover-binary-search-tree) | Medium |
-| <span id="100">100</span> | [Same Tree](https://leetcode.com/problems/same-tree "相同的树") | [Go](../problems/same-tree) | Easy |
-| <span id="101">101</span> | [Symmetric Tree](https://leetcode.com/problems/symmetric-tree "对称二叉树") | [Go](../problems/symmetric-tree) | Easy |
-| <span id="102">102</span> | [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal "二叉树的层序遍历") | [Go](../problems/binary-tree-level-order-traversal) | Medium |
-| <span id="103">103</span> | [Binary Tree Zigzag Level Order Traversal](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal "二叉树的锯齿形层序遍历") | [Go](../problems/binary-tree-zigzag-level-order-traversal) | Medium |
-| <span id="104">104</span> | [Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree "二叉树的最大深度") | [Go](../problems/maximum-depth-of-binary-tree) | Easy |
-| <span id="105">105</span> | [Construct Binary Tree from Preorder and Inorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal "从前序与中序遍历序列构造二叉树") | [Go](../problems/construct-binary-tree-from-preorder-and-inorder-traversal) | Medium |
-| <span id="106">106</span> | [Construct Binary Tree from Inorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal "从中序与后序遍历序列构造二叉树") | [Go](../problems/construct-binary-tree-from-inorder-and-postorder-traversal) | Medium |
-| <span id="107">107</span> | [Binary Tree Level Order Traversal II](https://leetcode.com/problems/binary-tree-level-order-traversal-ii "二叉树的层序遍历 II") | [Go](../problems/binary-tree-level-order-traversal-ii) | Medium |
-| <span id="108">108</span> | [Convert Sorted Array to Binary Search Tree](https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree "将有序数组转换为二叉搜索树") | [Go](../problems/convert-sorted-array-to-binary-search-tree) | Easy |
-| <span id="109">109</span> | [Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree "有序链表转换二叉搜索树") | [Go](../problems/convert-sorted-list-to-binary-search-tree) | Medium |
-| <span id="110">110</span> | [Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree "平衡二叉树") | [Go](../problems/balanced-binary-tree) | Easy |
-| <span id="111">111</span> | [Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree "二叉树的最小深度") | [Go](../problems/minimum-depth-of-binary-tree) | Easy |
-| <span id="112">112</span> | [Path Sum](https://leetcode.com/problems/path-sum "路径总和") | [Go](../problems/path-sum) | Easy |
-| <span id="113">113</span> | [Path Sum II](https://leetcode.com/problems/path-sum-ii "路径总和 II") | [Go](../problems/path-sum-ii) | Medium |
-| <span id="114">114</span> | [Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list "二叉树展开为链表") | [Go](../problems/flatten-binary-tree-to-linked-list) | Medium |
-| <span id="115">115</span> | [Distinct Subsequences](https://leetcode.com/problems/distinct-subsequences "不同的子序列") | [Go](../problems/distinct-subsequences) | Hard |
-| <span id="116">116</span> | [Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node "填充每个节点的下一个右侧节点指针") | [Go](../problems/populating-next-right-pointers-in-each-node) | Medium |
-| <span id="117">117</span> | [Populating Next Right Pointers in Each Node II](https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii "填充每个节点的下一个右侧节点指针 II") | [Go](../problems/populating-next-right-pointers-in-each-node-ii) | Medium |
-| <span id="118">118</span> | [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle "杨辉三角") | [Go](../problems/pascals-triangle) | Easy |
-| <span id="119">119</span> | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii "杨辉三角 II") | [Go](../problems/pascals-triangle-ii) | Easy |
-| <span id="120">120</span> | [Triangle](https://leetcode.com/problems/triangle "三角形最小路径和") | [Go](../problems/triangle) | Medium |
-| <span id="121">121</span> | [Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock "买卖股票的最佳时机") | [Go](../problems/best-time-to-buy-and-sell-stock) | Easy |
-| <span id="122">122</span> | [Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii "买卖股票的最佳时机 II") | [Go](../problems/best-time-to-buy-and-sell-stock-ii) | Medium |
-| <span id="123">123</span> | [Best Time to Buy and Sell Stock III](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii "买卖股票的最佳时机 III") | [Go](../problems/best-time-to-buy-and-sell-stock-iii) | Hard |
-| <span id="124">124</span> | [Binary Tree Maximum Path Sum](https://leetcode.com/problems/binary-tree-maximum-path-sum "二叉树中的最大路径和") | [Go](../problems/binary-tree-maximum-path-sum) | Hard |
-| <span id="125">125</span> | [Valid Palindrome](https://leetcode.com/problems/valid-palindrome "验证回文串") | [Go](../problems/valid-palindrome) | Easy |
-| <span id="126">126</span> | [Word Ladder II](https://leetcode.com/problems/word-ladder-ii "单词接龙 II") | [Go](../problems/word-ladder-ii) | Hard |
-| <span id="127">127</span> | [Word Ladder](https://leetcode.com/problems/word-ladder "单词接龙") | [Go](../problems/word-ladder) | Hard |
-| <span id="128">128</span> | [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence "最长连续序列") | [Go](../problems/longest-consecutive-sequence) | Medium |
-| <span id="129">129</span> | [Sum Root to Leaf Numbers](https://leetcode.com/problems/sum-root-to-leaf-numbers "求根节点到叶节点数字之和") | [Go](../problems/sum-root-to-leaf-numbers) | Medium |
-| <span id="130">130</span> | [Surrounded Regions](https://leetcode.com/problems/surrounded-regions "被围绕的区域") | [Go](../problems/surrounded-regions) | Medium |
-| <span id="131">131</span> | [Palindrome Partitioning](https://leetcode.com/problems/palindrome-partitioning "分割回文串") | [Go](../problems/palindrome-partitioning) | Medium |
-| <span id="132">132</span> | [Palindrome Partitioning II](https://leetcode.com/problems/palindrome-partitioning-ii "分割回文串 II") | [Go](../problems/palindrome-partitioning-ii) | Hard |
-| <span id="133">133</span> | [Clone Graph](https://leetcode.com/problems/clone-graph "克隆图") | [Go](../problems/clone-graph) | Medium |
-| <span id="134">134</span> | [Gas Station](https://leetcode.com/problems/gas-station "加油站") | [Go](../problems/gas-station) | Medium |
-| <span id="135">135</span> | [Candy](https://leetcode.com/problems/candy "分发糖果") | [Go](../problems/candy) | Hard |
-| <span id="136">136</span> | [Single Number](https://leetcode.com/problems/single-number "只出现一次的数字") | [Go](../problems/single-number) | Easy |
-| <span id="137">137</span> | [Single Number II](https://leetcode.com/problems/single-number-ii "只出现一次的数字 II") | [Go](../problems/single-number-ii) | Medium |
-| <span id="138">138</span> | [Copy List with Random Pointer](https://leetcode.com/problems/copy-list-with-random-pointer "复制带随机指针的链表") | [Go](../problems/copy-list-with-random-pointer) | Medium |
-| <span id="139">139</span> | [Word Break](https://leetcode.com/problems/word-break "单词拆分") | [Go](../problems/word-break) | Medium |
-| <span id="140">140</span> | [Word Break II](https://leetcode.com/problems/word-break-ii "单词拆分 II") | [Go](../problems/word-break-ii) | Hard |
-| <span id="141">141</span> | [Linked List Cycle](https://leetcode.com/problems/linked-list-cycle "环形链表") | [Go](../problems/linked-list-cycle) | Easy |
-| <span id="142">142</span> | [Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii "环形链表 II") | [Go](../problems/linked-list-cycle-ii) | Medium |
-| <span id="143">143</span> | [Reorder List](https://leetcode.com/problems/reorder-list "重排链表") | [Go](../problems/reorder-list) | Medium |
-| <span id="144">144</span> | [Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal "二叉树的前序遍历") | [Go](../problems/binary-tree-preorder-traversal) | Easy |
-| <span id="145">145</span> | [Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal "二叉树的后序遍历") | [Go](../problems/binary-tree-postorder-traversal) | Easy |
-| <span id="146">146</span> | [LRU Cache](https://leetcode.com/problems/lru-cache "LRU 缓存") | [Go](../problems/lru-cache) | Medium |
-| <span id="147">147</span> | [Insertion Sort List](https://leetcode.com/problems/insertion-sort-list "对链表进行插入排序") | [Go](../problems/insertion-sort-list) | Medium |
-| <span id="148">148</span> | [Sort List](https://leetcode.com/problems/sort-list "排序链表") | [Go](../problems/sort-list) | Medium |
-| <span id="149">149</span> | [Max Points on a Line](https://leetcode.com/problems/max-points-on-a-line "直线上最多的点数") | [Go](../problems/max-points-on-a-line) | Hard |
-| <span id="150">150</span> | [Evaluate Reverse Polish Notation](https://leetcode.com/problems/evaluate-reverse-polish-notation "逆波兰表达式求值") | [Go](../problems/evaluate-reverse-polish-notation) | Medium |
-| <span id="151">151</span> | [Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string "翻转字符串里的单词") | [Go](../problems/reverse-words-in-a-string) | Medium |
-| <span id="152">152</span> | [Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray "乘积最大子数组") | [Go](../problems/maximum-product-subarray) | Medium |
-| <span id="153">153</span> | [Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array "寻找旋转排序数组中的最小值") | [Go](../problems/find-minimum-in-rotated-sorted-array) | Medium |
-| <span id="154">154</span> | [Find Minimum in Rotated Sorted Array II](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii "寻找旋转排序数组中的最小值 II") | [Go](../problems/find-minimum-in-rotated-sorted-array-ii) | Hard |
-| <span id="155">155</span> | [Min Stack](https://leetcode.com/problems/min-stack "最小栈") | [Go](../problems/min-stack) | Easy |
-| <span id="156">156</span> | [Binary Tree Upside Down](https://leetcode.com/problems/binary-tree-upside-down "上下翻转二叉树") 🔒 | [Go](../problems/binary-tree-upside-down) | Medium |
-| <span id="157">157</span> | [Read N Characters Given Read4](https://leetcode.com/problems/read-n-characters-given-read4 "用 Read4 读取 N 个字符") 🔒 | [Go](../problems/read-n-characters-given-read4) | Easy |
-| <span id="158">158</span> | [Read N Characters Given read4 II - Call Multiple Times](https://leetcode.com/problems/read-n-characters-given-read4-ii-call-multiple-times "用 Read4 读取 N 个字符 II") 🔒 | [Go](../problems/read-n-characters-given-read4-ii-call-multiple-times) | Hard |
-| <span id="159">159</span> | [Longest Substring with At Most Two Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters "至多包含两个不同字符的最长子串") 🔒 | [Go](../problems/longest-substring-with-at-most-two-distinct-characters) | Medium |
-| <span id="160">160</span> | [Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists "相交链表") | [Go](../problems/intersection-of-two-linked-lists) | Easy |
-| <span id="161">161</span> | [One Edit Distance](https://leetcode.com/problems/one-edit-distance "相隔为 1 的编辑距离") 🔒 | [Go](../problems/one-edit-distance) | Medium |
-| <span id="162">162</span> | [Find Peak Element](https://leetcode.com/problems/find-peak-element "寻找峰值") | [Go](../problems/find-peak-element) | Medium |
-| <span id="163">163</span> | [Missing Ranges](https://leetcode.com/problems/missing-ranges "缺失的区间") 🔒 | [Go](../problems/missing-ranges) | Easy |
-| <span id="164">164</span> | [Maximum Gap](https://leetcode.com/problems/maximum-gap "最大间距") | [Go](../problems/maximum-gap) | Hard |
-| <span id="165">165</span> | [Compare Version Numbers](https://leetcode.com/problems/compare-version-numbers "比较版本号") | [Go](../problems/compare-version-numbers) | Medium |
-| <span id="166">166</span> | [Fraction to Recurring Decimal](https://leetcode.com/problems/fraction-to-recurring-decimal "分数到小数") | [Go](../problems/fraction-to-recurring-decimal) | Medium |
-| <span id="167">167</span> | [Two Sum II - Input Array Is Sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted "两数之和 II - 输入有序数组") | [Go](../problems/two-sum-ii-input-array-is-sorted) | Medium |
-| <span id="168">168</span> | [Excel Sheet Column Title](https://leetcode.com/problems/excel-sheet-column-title "Excel表列名称") | [Go](../problems/excel-sheet-column-title) | Easy |
-| <span id="169">169</span> | [Majority Element](https://leetcode.com/problems/majority-element "多数元素") | [Go](../problems/majority-element) | Easy |
-| <span id="170">170</span> | [Two Sum III - Data structure design](https://leetcode.com/problems/two-sum-iii-data-structure-design "两数之和 III - 数据结构设计") 🔒 | [Go](../problems/two-sum-iii-data-structure-design) | Easy |
-| <span id="171">171</span> | [Excel Sheet Column Number](https://leetcode.com/problems/excel-sheet-column-number "Excel 表列序号") | [Go](../problems/excel-sheet-column-number) | Easy |
-| <span id="172">172</span> | [Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes "阶乘后的零") | [Go](../problems/factorial-trailing-zeroes) | Medium |
-| <span id="173">173</span> | [Binary Search Tree Iterator](https://leetcode.com/problems/binary-search-tree-iterator "二叉搜索树迭代器") | [Go](../problems/binary-search-tree-iterator) | Medium |
-| <span id="174">174</span> | [Dungeon Game](https://leetcode.com/problems/dungeon-game "地下城游戏") | [Go](../problems/dungeon-game) | Hard |
-| <span id="175">175</span> | [Combine Two Tables](https://leetcode.com/problems/combine-two-tables "组合两个表") | [MySQL](../problems/combine-two-tables) | Easy |
-| <span id="176">176</span> | [Second Highest Salary](https://leetcode.com/problems/second-highest-salary "第二高的薪水") | [MySQL](../problems/second-highest-salary) | Medium |
-| <span id="177">177</span> | [Nth Highest Salary](https://leetcode.com/problems/nth-highest-salary "第N高的薪水") | [MySQL](../problems/nth-highest-salary) | Medium |
-| <span id="178">178</span> | [Rank Scores](https://leetcode.com/problems/rank-scores "分数排名") | [MySQL](../problems/rank-scores) | Medium |
-| <span id="179">179</span> | [Largest Number](https://leetcode.com/problems/largest-number "最大数") | [Go](../problems/largest-number) | Medium |
-| <span id="180">180</span> | [Consecutive Numbers](https://leetcode.com/problems/consecutive-numbers "连续出现的数字") | [MySQL](../problems/consecutive-numbers) | Medium |
-| <span id="181">181</span> | [Employees Earning More Than Their Managers](https://leetcode.com/problems/employees-earning-more-than-their-managers "超过经理收入的员工") | [MySQL](../problems/employees-earning-more-than-their-managers) | Easy |
-| <span id="182">182</span> | [Duplicate Emails](https://leetcode.com/problems/duplicate-emails "查找重复的电子邮箱") | [MySQL](../problems/duplicate-emails) | Easy |
-| <span id="183">183</span> | [Customers Who Never Order](https://leetcode.com/problems/customers-who-never-order "从不订购的客户") | [MySQL](../problems/customers-who-never-order) | Easy |
-| <span id="184">184</span> | [Department Highest Salary](https://leetcode.com/problems/department-highest-salary "部门工资最高的员工") | [MySQL](../problems/department-highest-salary) | Medium |
-| <span id="185">185</span> | [Department Top Three Salaries](https://leetcode.com/problems/department-top-three-salaries "部门工资前三高的所有员工") | [MySQL](../problems/department-top-three-salaries) | Hard |
-| <span id="186">186</span> | [Reverse Words in a String II](https://leetcode.com/problems/reverse-words-in-a-string-ii "翻转字符串里的单词 II") 🔒 | [Go](../problems/reverse-words-in-a-string-ii) | Medium |
-| <span id="187">187</span> | [Repeated DNA Sequences](https://leetcode.com/problems/repeated-dna-sequences "重复的DNA序列") | [Go](../problems/repeated-dna-sequences) | Medium |
-| <span id="188">188</span> | [Best Time to Buy and Sell Stock IV](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv "买卖股票的最佳时机 IV") | [Go](../problems/best-time-to-buy-and-sell-stock-iv) | Hard |
-| <span id="189">189</span> | [Rotate Array](https://leetcode.com/problems/rotate-array "轮转数组") | [Go](../problems/rotate-array) | Medium |
-| <span id="190">190</span> | [Reverse Bits](https://leetcode.com/problems/reverse-bits "颠倒二进制位") | [Go](../problems/reverse-bits) | Easy |
-| <span id="191">191</span> | [Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits "位1的个数") | [Go](../problems/number-of-1-bits) | Easy |
-| <span id="192">192</span> | [Word Frequency](https://leetcode.com/problems/word-frequency "统计词频") | [Bash](../problems/word-frequency) | Medium |
-| <span id="193">193</span> | [Valid Phone Numbers](https://leetcode.com/problems/valid-phone-numbers "有效电话号码") | [Bash](../problems/valid-phone-numbers) | Easy |
-| <span id="194">194</span> | [Transpose File](https://leetcode.com/problems/transpose-file "转置文件") | [Bash](../problems/transpose-file) | Medium |
-| <span id="195">195</span> | [Tenth Line](https://leetcode.com/problems/tenth-line "第十行") | [Bash](../problems/tenth-line) | Easy |
-| <span id="196">196</span> | [Delete Duplicate Emails](https://leetcode.com/problems/delete-duplicate-emails "删除重复的电子邮箱") | [MySQL](../problems/delete-duplicate-emails) | Easy |
-| <span id="197">197</span> | [Rising Temperature](https://leetcode.com/problems/rising-temperature "上升的温度") | [MySQL](../problems/rising-temperature) | Easy |
-| <span id="198">198</span> | [House Robber](https://leetcode.com/problems/house-robber "打家劫舍") | [Go](../problems/house-robber) | Medium |
-| <span id="199">199</span> | [Binary Tree Right Side View](https://leetcode.com/problems/binary-tree-right-side-view "二叉树的右视图") | [Go](../problems/binary-tree-right-side-view) | Medium |
-| <span id="200">200</span> | [Number of Islands](https://leetcode.com/problems/number-of-islands "岛屿数量") | [Go](../problems/number-of-islands) | Medium |
-| <span id="201">201</span> | [Bitwise AND of Numbers Range](https://leetcode.com/problems/bitwise-and-of-numbers-range "数字范围按位与") | [Go](../problems/bitwise-and-of-numbers-range) | Medium |
-| <span id="202">202</span> | [Happy Number](https://leetcode.com/problems/happy-number "快乐数") | [Go](../problems/happy-number) | Easy |
-| <span id="203">203</span> | [Remove Linked List Elements](https://leetcode.com/problems/remove-linked-list-elements "移除链表元素") | [Go](../problems/remove-linked-list-elements) | Easy |
-| <span id="204">204</span> | [Count Primes](https://leetcode.com/problems/count-primes "计数质数") | [Go](../problems/count-primes) | Medium |
-| <span id="205">205</span> | [Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings "同构字符串") | [Go](../problems/isomorphic-strings) | Easy |
-| <span id="206">206</span> | [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list "反转链表") | [Go](../problems/reverse-linked-list) | Easy |
-| <span id="207">207</span> | [Course Schedule](https://leetcode.com/problems/course-schedule "课程表") | [Go](../problems/course-schedule) | Medium |
-| <span id="208">208</span> | [Implement Trie (Prefix Tree)](https://leetcode.com/problems/implement-trie-prefix-tree "实现 Trie (前缀树)") | [Go](../problems/implement-trie-prefix-tree) | Medium |
-| <span id="209">209</span> | [Minimum Size Subarray Sum](https://leetcode.com/problems/minimum-size-subarray-sum "长度最小的子数组") | [Go](../problems/minimum-size-subarray-sum) | Medium |
-| <span id="210">210</span> | [Course Schedule II](https://leetcode.com/problems/course-schedule-ii "课程表 II") | [Go](../problems/course-schedule-ii) | Medium |
-| <span id="211">211</span> | [Design Add and Search Words Data Structure](https://leetcode.com/problems/design-add-and-search-words-data-structure "添加与搜索单词 - 数据结构设计") | [Go](../problems/design-add-and-search-words-data-structure) | Medium |
-| <span id="212">212</span> | [Word Search II](https://leetcode.com/problems/word-search-ii "单词搜索 II") | [Go](../problems/word-search-ii) | Hard |
-| <span id="213">213</span> | [House Robber II](https://leetcode.com/problems/house-robber-ii "打家劫舍 II") | [Go](../problems/house-robber-ii) | Medium |
-| <span id="214">214</span> | [Shortest Palindrome](https://leetcode.com/problems/shortest-palindrome "最短回文串") | [Go](../problems/shortest-palindrome) | Hard |
-| <span id="215">215</span> | [Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array "数组中的第K个最大元素") | [Go](../problems/kth-largest-element-in-an-array) | Medium |
-| <span id="216">216</span> | [Combination Sum III](https://leetcode.com/problems/combination-sum-iii "组合总和 III") | [Go](../problems/combination-sum-iii) | Medium |
-| <span id="217">217</span> | [Contains Duplicate](https://leetcode.com/problems/contains-duplicate "存在重复元素") | [Go](../problems/contains-duplicate) | Easy |
-| <span id="218">218</span> | [The Skyline Problem](https://leetcode.com/problems/the-skyline-problem "天际线问题") | [Go](../problems/the-skyline-problem) | Hard |
-| <span id="219">219</span> | [Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii "存在重复元素 II") | [Go](../problems/contains-duplicate-ii) | Easy |
-| <span id="220">220</span> | [Contains Duplicate III](https://leetcode.com/problems/contains-duplicate-iii "存在重复元素 III") | [Go](../problems/contains-duplicate-iii) | Medium |
-| <span id="221">221</span> | [Maximal Square](https://leetcode.com/problems/maximal-square "最大正方形") | [Go](../problems/maximal-square) | Medium |
-| <span id="222">222</span> | [Count Complete Tree Nodes](https://leetcode.com/problems/count-complete-tree-nodes "完全二叉树的节点个数") | [Go](../problems/count-complete-tree-nodes) | Medium |
-| <span id="223">223</span> | [Rectangle Area](https://leetcode.com/problems/rectangle-area "矩形面积") | [Go](../problems/rectangle-area) | Medium |
-| <span id="224">224</span> | [Basic Calculator](https://leetcode.com/problems/basic-calculator "基本计算器") | [Go](../problems/basic-calculator) | Hard |
-| <span id="225">225</span> | [Implement Stack using Queues](https://leetcode.com/problems/implement-stack-using-queues "用队列实现栈") | [Go](../problems/implement-stack-using-queues) | Easy |
-| <span id="226">226</span> | [Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree "翻转二叉树") | [Go](../problems/invert-binary-tree) | Easy |
-| <span id="227">227</span> | [Basic Calculator II](https://leetcode.com/problems/basic-calculator-ii "基本计算器 II") | [Go](../problems/basic-calculator-ii) | Medium |
-| <span id="228">228</span> | [Summary Ranges](https://leetcode.com/problems/summary-ranges "汇总区间") | [Go](../problems/summary-ranges) | Easy |
-| <span id="229">229</span> | [Majority Element II](https://leetcode.com/problems/majority-element-ii "求众数 II") | [Go](../problems/majority-element-ii) | Medium |
-| <span id="230">230</span> | [Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst "二叉搜索树中第K小的元素") | [Go](../problems/kth-smallest-element-in-a-bst) | Medium |
-| <span id="231">231</span> | [Power of Two](https://leetcode.com/problems/power-of-two "2 的幂") | [Go](../problems/power-of-two) | Easy |
-| <span id="232">232</span> | [Implement Queue using Stacks](https://leetcode.com/problems/implement-queue-using-stacks "用栈实现队列") | [Go](../problems/implement-queue-using-stacks) | Easy |
-| <span id="233">233</span> | [Number of Digit One](https://leetcode.com/problems/number-of-digit-one "数字 1 的个数") | [Go](../problems/number-of-digit-one) | Hard |
-| <span id="234">234</span> | [Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list "回文链表") | [Go](../problems/palindrome-linked-list) | Easy |
-| <span id="235">235</span> | [Lowest Common Ancestor of a Binary Search Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree "二叉搜索树的最近公共祖先") | [Go](../problems/lowest-common-ancestor-of-a-binary-search-tree) | Easy |
-| <span id="236">236</span> | [Lowest Common Ancestor of a Binary Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree "二叉树的最近公共祖先") | [Go](../problems/lowest-common-ancestor-of-a-binary-tree) | Medium |
-| <span id="237">237</span> | [Delete Node in a Linked List](https://leetcode.com/problems/delete-node-in-a-linked-list "删除链表中的节点") | [Go](../problems/delete-node-in-a-linked-list) | Easy |
-| <span id="238">238</span> | [Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self "除自身以外数组的乘积") | [Go](../problems/product-of-array-except-self) | Medium |
-| <span id="239">239</span> | [Sliding Window Maximum](https://leetcode.com/problems/sliding-window-maximum "滑动窗口最大值") | [Go](../problems/sliding-window-maximum) | Hard |
-| <span id="240">240</span> | [Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii "搜索二维矩阵 II") | [Go](../problems/search-a-2d-matrix-ii) | Medium |
-| <span id="241">241</span> | [Different Ways to Add Parentheses](https://leetcode.com/problems/different-ways-to-add-parentheses "为运算表达式设计优先级") | [Go](../problems/different-ways-to-add-parentheses) | Medium |
-| <span id="242">242</span> | [Valid Anagram](https://leetcode.com/problems/valid-anagram "有效的字母异位词") | [Go](../problems/valid-anagram) | Easy |
-| <span id="243">243</span> | [Shortest Word Distance](https://leetcode.com/problems/shortest-word-distance "最短单词距离") 🔒 | [Go](../problems/shortest-word-distance) | Easy |
-| <span id="244">244</span> | [Shortest Word Distance II](https://leetcode.com/problems/shortest-word-distance-ii "最短单词距离 II") 🔒 | [Go](../problems/shortest-word-distance-ii) | Medium |
-| <span id="245">245</span> | [Shortest Word Distance III](https://leetcode.com/problems/shortest-word-distance-iii "最短单词距离 III") 🔒 | [Go](../problems/shortest-word-distance-iii) | Medium |
-| <span id="246">246</span> | [Strobogrammatic Number](https://leetcode.com/problems/strobogrammatic-number "中心对称数") 🔒 | [Go](../problems/strobogrammatic-number) | Easy |
-| <span id="247">247</span> | [Strobogrammatic Number II](https://leetcode.com/problems/strobogrammatic-number-ii "中心对称数 II") 🔒 | [Go](../problems/strobogrammatic-number-ii) | Medium |
-| <span id="248">248</span> | [Strobogrammatic Number III](https://leetcode.com/problems/strobogrammatic-number-iii "中心对称数 III") 🔒 | [Go](../problems/strobogrammatic-number-iii) | Hard |
-| <span id="249">249</span> | [Group Shifted Strings](https://leetcode.com/problems/group-shifted-strings "移位字符串分组") 🔒 | [Go](../problems/group-shifted-strings) | Medium |
-| <span id="250">250</span> | [Count Univalue Subtrees](https://leetcode.com/problems/count-univalue-subtrees "统计同值子树") 🔒 | [Go](../problems/count-univalue-subtrees) | Medium |
-| <span id="251">251</span> | [Flatten 2D Vector](https://leetcode.com/problems/flatten-2d-vector "展开二维向量") 🔒 | [Go](../problems/flatten-2d-vector) | Medium |
-| <span id="252">252</span> | [Meeting Rooms](https://leetcode.com/problems/meeting-rooms "会议室") 🔒 | [Go](../problems/meeting-rooms) | Easy |
-| <span id="253">253</span> | [Meeting Rooms II](https://leetcode.com/problems/meeting-rooms-ii "会议室 II") 🔒 | [Go](../problems/meeting-rooms-ii) | Medium |
-| <span id="254">254</span> | [Factor Combinations](https://leetcode.com/problems/factor-combinations "因子的组合") 🔒 | [Go](../problems/factor-combinations) | Medium |
-| <span id="255">255</span> | [Verify Preorder Sequence in Binary Search Tree](https://leetcode.com/problems/verify-preorder-sequence-in-binary-search-tree "验证前序遍历序列二叉搜索树") 🔒 | [Go](../problems/verify-preorder-sequence-in-binary-search-tree) | Medium |
-| <span id="256">256</span> | [Paint House](https://leetcode.com/problems/paint-house "粉刷房子") 🔒 | [Go](../problems/paint-house) | Medium |
-| <span id="257">257</span> | [Binary Tree Paths](https://leetcode.com/problems/binary-tree-paths "二叉树的所有路径") | [Go](../problems/binary-tree-paths) | Easy |
-| <span id="258">258</span> | [Add Digits](https://leetcode.com/problems/add-digits "各位相加") | [Go](../problems/add-digits) | Easy |
-| <span id="259">259</span> | [3Sum Smaller](https://leetcode.com/problems/3sum-smaller "较小的三数之和") 🔒 | [Go](../problems/3sum-smaller) | Medium |
-| <span id="260">260</span> | [Single Number III](https://leetcode.com/problems/single-number-iii "只出现一次的数字 III") | [Go](../problems/single-number-iii) | Medium |
-| <span id="261">261</span> | [Graph Valid Tree](https://leetcode.com/problems/graph-valid-tree "以图判树") 🔒 | [Go](../problems/graph-valid-tree) | Medium |
-| <span id="262">262</span> | [Trips and Users](https://leetcode.com/problems/trips-and-users "行程和用户") | [MySQL](../problems/trips-and-users) | Hard |
-| <span id="263">263</span> | [Ugly Number](https://leetcode.com/problems/ugly-number "丑数") | [Go](../problems/ugly-number) | Easy |
-| <span id="264">264</span> | [Ugly Number II](https://leetcode.com/problems/ugly-number-ii "丑数 II") | [Go](../problems/ugly-number-ii) | Medium |
-| <span id="265">265</span> | [Paint House II](https://leetcode.com/problems/paint-house-ii "粉刷房子 II") 🔒 | [Go](../problems/paint-house-ii) | Hard |
-| <span id="266">266</span> | [Palindrome Permutation](https://leetcode.com/problems/palindrome-permutation "回文排列") 🔒 | [Go](../problems/palindrome-permutation) | Easy |
-| <span id="267">267</span> | [Palindrome Permutation II](https://leetcode.com/problems/palindrome-permutation-ii "回文排列 II") 🔒 | [Go](../problems/palindrome-permutation-ii) | Medium |
-| <span id="268">268</span> | [Missing Number](https://leetcode.com/problems/missing-number "丢失的数字") | [Go](../problems/missing-number) | Easy |
-| <span id="269">269</span> | [Alien Dictionary](https://leetcode.com/problems/alien-dictionary "火星词典") 🔒 | [Go](../problems/alien-dictionary) | Hard |
-| <span id="270">270</span> | [Closest Binary Search Tree Value](https://leetcode.com/problems/closest-binary-search-tree-value "最接近的二叉搜索树值") 🔒 | [Go](../problems/closest-binary-search-tree-value) | Easy |
-| <span id="271">271</span> | [Encode and Decode Strings](https://leetcode.com/problems/encode-and-decode-strings "字符串的编码与解码") 🔒 | [Go](../problems/encode-and-decode-strings) | Medium |
-| <span id="272">272</span> | [Closest Binary Search Tree Value II](https://leetcode.com/problems/closest-binary-search-tree-value-ii "最接近的二叉搜索树值 II") 🔒 | [Go](../problems/closest-binary-search-tree-value-ii) | Hard |
-| <span id="273">273</span> | [Integer to English Words](https://leetcode.com/problems/integer-to-english-words "整数转换英文表示") | [Go](../problems/integer-to-english-words) | Hard |
-| <span id="274">274</span> | [H-Index](https://leetcode.com/problems/h-index "H 指数") | [Go](../problems/h-index) | Medium |
-| <span id="275">275</span> | [H-Index II](https://leetcode.com/problems/h-index-ii "H 指数 II") | [Go](../problems/h-index-ii) | Medium |
-| <span id="276">276</span> | [Paint Fence](https://leetcode.com/problems/paint-fence "栅栏涂色") 🔒 | [Go](../problems/paint-fence) | Medium |
-| <span id="277">277</span> | [Find the Celebrity](https://leetcode.com/problems/find-the-celebrity "搜寻名人") 🔒 | [Go](../problems/find-the-celebrity) | Medium |
-| <span id="278">278</span> | [First Bad Version](https://leetcode.com/problems/first-bad-version "第一个错误的版本") | [Go](../problems/first-bad-version) | Easy |
-| <span id="279">279</span> | [Perfect Squares](https://leetcode.com/problems/perfect-squares "完全平方数") | [Go](../problems/perfect-squares) | Medium |
-| <span id="280">280</span> | [Wiggle Sort](https://leetcode.com/problems/wiggle-sort "摆动排序") 🔒 | [Go](../problems/wiggle-sort) | Medium |
-| <span id="281">281</span> | [Zigzag Iterator](https://leetcode.com/problems/zigzag-iterator "锯齿迭代器") 🔒 | [Go](../problems/zigzag-iterator) | Medium |
-| <span id="282">282</span> | [Expression Add Operators](https://leetcode.com/problems/expression-add-operators "给表达式添加运算符") | [Go](../problems/expression-add-operators) | Hard |
-| <span id="283">283</span> | [Move Zeroes](https://leetcode.com/problems/move-zeroes "移动零") | [Go](../problems/move-zeroes) | Easy |
-| <span id="284">284</span> | [Peeking Iterator](https://leetcode.com/problems/peeking-iterator "顶端迭代器") | [Go](../problems/peeking-iterator) | Medium |
-| <span id="285">285</span> | [Inorder Successor in BST](https://leetcode.com/problems/inorder-successor-in-bst "二叉搜索树中的中序后继") 🔒 | [Go](../problems/inorder-successor-in-bst) | Medium |
-| <span id="286">286</span> | [Walls and Gates](https://leetcode.com/problems/walls-and-gates "墙与门") 🔒 | [Go](../problems/walls-and-gates) | Medium |
-| <span id="287">287</span> | [Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number "寻找重复数") | [Go](../problems/find-the-duplicate-number) | Medium |
-| <span id="288">288</span> | [Unique Word Abbreviation](https://leetcode.com/problems/unique-word-abbreviation "单词的唯一缩写") 🔒 | [Go](../problems/unique-word-abbreviation) | Medium |
-| <span id="289">289</span> | [Game of Life](https://leetcode.com/problems/game-of-life "生命游戏") | [Go](../problems/game-of-life) | Medium |
-| <span id="290">290</span> | [Word Pattern](https://leetcode.com/problems/word-pattern "单词规律") | [Go](../problems/word-pattern) | Easy |
-| <span id="291">291</span> | [Word Pattern II](https://leetcode.com/problems/word-pattern-ii "单词规律 II") 🔒 | [Go](../problems/word-pattern-ii) | Medium |
-| <span id="292">292</span> | [Nim Game](https://leetcode.com/problems/nim-game "Nim 游戏") | [Go](../problems/nim-game) | Easy |
-| <span id="293">293</span> | [Flip Game](https://leetcode.com/problems/flip-game "翻转游戏") 🔒 | [Go](../problems/flip-game) | Easy |
-| <span id="294">294</span> | [Flip Game II](https://leetcode.com/problems/flip-game-ii "翻转游戏 II") 🔒 | [Go](../problems/flip-game-ii) | Medium |
-| <span id="295">295</span> | [Find Median from Data Stream](https://leetcode.com/problems/find-median-from-data-stream "数据流的中位数") | [Go](../problems/find-median-from-data-stream) | Hard |
-| <span id="296">296</span> | [Best Meeting Point](https://leetcode.com/problems/best-meeting-point "最佳的碰头地点") 🔒 | [Go](../problems/best-meeting-point) | Hard |
-| <span id="297">297</span> | [Serialize and Deserialize Binary Tree](https://leetcode.com/problems/serialize-and-deserialize-binary-tree "二叉树的序列化与反序列化") | [Go](../problems/serialize-and-deserialize-binary-tree) | Hard |
-| <span id="298">298</span> | [Binary Tree Longest Consecutive Sequence](https://leetcode.com/problems/binary-tree-longest-consecutive-sequence "二叉树最长连续序列") 🔒 | [Go](../problems/binary-tree-longest-consecutive-sequence) | Medium |
-| <span id="299">299</span> | [Bulls and Cows](https://leetcode.com/problems/bulls-and-cows "猜数字游戏") | [Go](../problems/bulls-and-cows) | Medium |
-| <span id="300">300</span> | [Longest Increasing Subsequence](https://leetcode.com/problems/longest-increasing-subsequence "最长递增子序列") | [Go](../problems/longest-increasing-subsequence) | Medium |
diff --git a/readme/1201-1500.md b/readme/1201-1500.md
deleted file mode 100644
index cd9ca1be8..000000000
--- a/readme/1201-1500.md
+++ /dev/null
@@ -1,388 +0,0 @@
-<!--|This file generated by command(leetcode readme); DO NOT EDIT.         |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-# [LeetCode](https://awesee.github.io/leetcode)
-LeetCode Problems' Solutions
-[[力扣](https://awesee.github.io/categories/leetcode/) ∙ [话题分类](https://github.com/awesee/leetcode/blob/master/tag/README.md)]
-
-[![Go](https://github.com/awesee/leetcode/workflows/Go/badge.svg)](https://github.com/awesee/leetcode/actions)
-[![codecov](https://codecov.io/gh/awesee/leetcode/branch/master/graph/badge.svg)](https://codecov.io/gh/awesee/leetcode)
-[![Go Report Card](https://goreportcard.com/badge/github.com/awesee/leetcode)](https://goreportcard.com/report/github.com/awesee/leetcode)
-[![GitHub contributors](https://img.shields.io/github/contributors/awesee/leetcode.svg)](https://github.com/awesee/leetcode/graphs/contributors)
-[![license](https://img.shields.io/github/license/awesee/leetcode.svg)](https://github.com/awesee/leetcode/blob/master/LICENSE)
-[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fawesee%2Fleetcode.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fawesee%2Fleetcode?ref=badge_shield)
-[![Join the chat](https://badges.gitter.im/awesee/leetcode.svg)](https://gitter.im/awesee/leetcode?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-
-<table><thead>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#1">[1-50]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#51">[51-100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#101">[101-150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#151">[151-200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#201">[201-250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#251">[251-300]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#301">[301-350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#351">[351-400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#401">[401-450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#451">[451-500]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#501">[501-550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#551">[551-600]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#601">[601-650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#651">[651-700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#701">[701-750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#751">[751-800]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#801">[801-850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#851">[851-900]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#901">[901-950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#951">[951-1000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1001">[1001-1050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1051">[1051-1100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1101">[1101-1150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1151">[1151-1200]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1201">[1201-1250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1251">[1251-1300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1301">[1301-1350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1351">[1351-1400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1401">[1401-1450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1451">[1451-1500]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1501">[1501-1550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1551">[1551-1600]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1601">[1601-1650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1651">[1651-1700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1701">[1701-1750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1751">[1751-1800]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1850">[1801-1850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1900">[1851-1900]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1950">[1901-1950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2000">[1951-2000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2050">[2001-2050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2100">[2051-2100]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2150">[2101-2150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2200">[2151-2200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2250">[2201-2250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2300">[2251-2300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2350">[2301-2350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2400">[2351-2400]</a></th>
-</tr>
-</thead></table>
-
-| # | Title | Solution | Difficulty |
-| :-: | - | - | :-: |
-| <span id="1201">1201</span> | [Ugly Number III](https://leetcode.com/problems/ugly-number-iii "丑数 III") | [Go](../problems/ugly-number-iii) | Medium |
-| <span id="1202">1202</span> | [Smallest String With Swaps](https://leetcode.com/problems/smallest-string-with-swaps "交换字符串中的元素") | [Go](../problems/smallest-string-with-swaps) | Medium |
-| <span id="1203">1203</span> | [Sort Items by Groups Respecting Dependencies](https://leetcode.com/problems/sort-items-by-groups-respecting-dependencies "项目管理") | [Go](../problems/sort-items-by-groups-respecting-dependencies) | Hard |
-| <span id="1204">1204</span> | [Last Person to Fit in the Bus](https://leetcode.com/problems/last-person-to-fit-in-the-bus "最后一个能进入电梯的人") 🔒 | [MySQL](../problems/last-person-to-fit-in-the-bus) | Medium |
-| <span id="1205">1205</span> | [Monthly Transactions II](https://leetcode.com/problems/monthly-transactions-ii "每月交易II") 🔒 | [MySQL](../problems/monthly-transactions-ii) | Medium |
-| <span id="1206">1206</span> | [Design Skiplist](https://leetcode.com/problems/design-skiplist "设计跳表") | [Go](../problems/design-skiplist) | Hard |
-| <span id="1207">1207</span> | [Unique Number of Occurrences](https://leetcode.com/problems/unique-number-of-occurrences "独一无二的出现次数") | [Go](../problems/unique-number-of-occurrences) | Easy |
-| <span id="1208">1208</span> | [Get Equal Substrings Within Budget](https://leetcode.com/problems/get-equal-substrings-within-budget "尽可能使字符串相等") | [Go](../problems/get-equal-substrings-within-budget) | Medium |
-| <span id="1209">1209</span> | [Remove All Adjacent Duplicates in String II](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string-ii "删除字符串中的所有相邻重复项 II") | [Go](../problems/remove-all-adjacent-duplicates-in-string-ii) | Medium |
-| <span id="1210">1210</span> | [Minimum Moves to Reach Target with Rotations](https://leetcode.com/problems/minimum-moves-to-reach-target-with-rotations "穿过迷宫的最少移动次数") | [Go](../problems/minimum-moves-to-reach-target-with-rotations) | Hard |
-| <span id="1211">1211</span> | [Queries Quality and Percentage](https://leetcode.com/problems/queries-quality-and-percentage "查询结果的质量和占比") 🔒 | [MySQL](../problems/queries-quality-and-percentage) | Easy |
-| <span id="1212">1212</span> | [Team Scores in Football Tournament](https://leetcode.com/problems/team-scores-in-football-tournament "查询球队积分") 🔒 | [MySQL](../problems/team-scores-in-football-tournament) | Medium |
-| <span id="1213">1213</span> | [Intersection of Three Sorted Arrays](https://leetcode.com/problems/intersection-of-three-sorted-arrays "三个有序数组的交集") 🔒 | [Go](../problems/intersection-of-three-sorted-arrays) | Easy |
-| <span id="1214">1214</span> | [Two Sum BSTs](https://leetcode.com/problems/two-sum-bsts "查找两棵二叉搜索树之和") 🔒 | [Go](../problems/two-sum-bsts) | Medium |
-| <span id="1215">1215</span> | [Stepping Numbers](https://leetcode.com/problems/stepping-numbers "步进数") 🔒 | [Go](../problems/stepping-numbers) | Medium |
-| <span id="1216">1216</span> | [Valid Palindrome III](https://leetcode.com/problems/valid-palindrome-iii "验证回文字符串 III") 🔒 | [Go](../problems/valid-palindrome-iii) | Hard |
-| <span id="1217">1217</span> | [Minimum Cost to Move Chips to The Same Position](https://leetcode.com/problems/minimum-cost-to-move-chips-to-the-same-position "玩筹码") | [Go](../problems/minimum-cost-to-move-chips-to-the-same-position) | Easy |
-| <span id="1218">1218</span> | [Longest Arithmetic Subsequence of Given Difference](https://leetcode.com/problems/longest-arithmetic-subsequence-of-given-difference "最长定差子序列") | [Go](../problems/longest-arithmetic-subsequence-of-given-difference) | Medium |
-| <span id="1219">1219</span> | [Path with Maximum Gold](https://leetcode.com/problems/path-with-maximum-gold "黄金矿工") | [Go](../problems/path-with-maximum-gold) | Medium |
-| <span id="1220">1220</span> | [Count Vowels Permutation](https://leetcode.com/problems/count-vowels-permutation "统计元音字母序列的数目") | [Go](../problems/count-vowels-permutation) | Hard |
-| <span id="1221">1221</span> | [Split a String in Balanced Strings](https://leetcode.com/problems/split-a-string-in-balanced-strings "分割平衡字符串") | [Go](../problems/split-a-string-in-balanced-strings) | Easy |
-| <span id="1222">1222</span> | [Queens That Can Attack the King](https://leetcode.com/problems/queens-that-can-attack-the-king "可以攻击国王的皇后") | [Go](../problems/queens-that-can-attack-the-king) | Medium |
-| <span id="1223">1223</span> | [Dice Roll Simulation](https://leetcode.com/problems/dice-roll-simulation "掷骰子模拟") | [Go](../problems/dice-roll-simulation) | Hard |
-| <span id="1224">1224</span> | [Maximum Equal Frequency](https://leetcode.com/problems/maximum-equal-frequency "最大相等频率") | [Go](../problems/maximum-equal-frequency) | Hard |
-| <span id="1225">1225</span> | [Report Contiguous Dates](https://leetcode.com/problems/report-contiguous-dates "报告系统状态的连续日期") 🔒 | [MySQL](../problems/report-contiguous-dates) | Hard |
-| <span id="1226">1226</span> | [The Dining Philosophers](https://leetcode.com/problems/the-dining-philosophers "哲学家进餐") | [Go](../problems/the-dining-philosophers) | Medium |
-| <span id="1227">1227</span> | [Airplane Seat Assignment Probability](https://leetcode.com/problems/airplane-seat-assignment-probability "飞机座位分配概率") | [Go](../problems/airplane-seat-assignment-probability) | Medium |
-| <span id="1228">1228</span> | [Missing Number In Arithmetic Progression](https://leetcode.com/problems/missing-number-in-arithmetic-progression "等差数列中缺失的数字") 🔒 | [Go](../problems/missing-number-in-arithmetic-progression) | Easy |
-| <span id="1229">1229</span> | [Meeting Scheduler](https://leetcode.com/problems/meeting-scheduler "安排会议日程") 🔒 | [Go](../problems/meeting-scheduler) | Medium |
-| <span id="1230">1230</span> | [Toss Strange Coins](https://leetcode.com/problems/toss-strange-coins "抛掷硬币") 🔒 | [Go](../problems/toss-strange-coins) | Medium |
-| <span id="1231">1231</span> | [Divide Chocolate](https://leetcode.com/problems/divide-chocolate "分享巧克力") 🔒 | [Go](../problems/divide-chocolate) | Hard |
-| <span id="1232">1232</span> | [Check If It Is a Straight Line](https://leetcode.com/problems/check-if-it-is-a-straight-line "缀点成线") | [Go](../problems/check-if-it-is-a-straight-line) | Easy |
-| <span id="1233">1233</span> | [Remove Sub-Folders from the Filesystem](https://leetcode.com/problems/remove-sub-folders-from-the-filesystem "删除子文件夹") | [Go](../problems/remove-sub-folders-from-the-filesystem) | Medium |
-| <span id="1234">1234</span> | [Replace the Substring for Balanced String](https://leetcode.com/problems/replace-the-substring-for-balanced-string "替换子串得到平衡字符串") | [Go](../problems/replace-the-substring-for-balanced-string) | Medium |
-| <span id="1235">1235</span> | [Maximum Profit in Job Scheduling](https://leetcode.com/problems/maximum-profit-in-job-scheduling "规划兼职工作") | [Go](../problems/maximum-profit-in-job-scheduling) | Hard |
-| <span id="1236">1236</span> | [Web Crawler](https://leetcode.com/problems/web-crawler "网络爬虫") 🔒 | [Go](../problems/web-crawler) | Medium |
-| <span id="1237">1237</span> | [Find Positive Integer Solution for a Given Equation](https://leetcode.com/problems/find-positive-integer-solution-for-a-given-equation "找出给定方程的正整数解") | [Go](../problems/find-positive-integer-solution-for-a-given-equation) | Medium |
-| <span id="1238">1238</span> | [Circular Permutation in Binary Representation](https://leetcode.com/problems/circular-permutation-in-binary-representation "循环码排列") | [Go](../problems/circular-permutation-in-binary-representation) | Medium |
-| <span id="1239">1239</span> | [Maximum Length of a Concatenated String with Unique Characters](https://leetcode.com/problems/maximum-length-of-a-concatenated-string-with-unique-characters "串联字符串的最大长度") | [Go](../problems/maximum-length-of-a-concatenated-string-with-unique-characters) | Medium |
-| <span id="1240">1240</span> | [Tiling a Rectangle with the Fewest Squares](https://leetcode.com/problems/tiling-a-rectangle-with-the-fewest-squares "铺瓷砖") | [Go](../problems/tiling-a-rectangle-with-the-fewest-squares) | Hard |
-| <span id="1241">1241</span> | [Number of Comments per Post](https://leetcode.com/problems/number-of-comments-per-post "每个帖子的评论数") 🔒 | [MySQL](../problems/number-of-comments-per-post) | Easy |
-| <span id="1242">1242</span> | [Web Crawler Multithreaded](https://leetcode.com/problems/web-crawler-multithreaded "多线程网页爬虫") 🔒 | [Go](../problems/web-crawler-multithreaded) | Medium |
-| <span id="1243">1243</span> | [Array Transformation](https://leetcode.com/problems/array-transformation "数组变换") 🔒 | [Go](../problems/array-transformation) | Easy |
-| <span id="1244">1244</span> | [Design A Leaderboard](https://leetcode.com/problems/design-a-leaderboard "力扣排行榜") 🔒 | [Go](../problems/design-a-leaderboard) | Medium |
-| <span id="1245">1245</span> | [Tree Diameter](https://leetcode.com/problems/tree-diameter "树的直径") 🔒 | [Go](../problems/tree-diameter) | Medium |
-| <span id="1246">1246</span> | [Palindrome Removal](https://leetcode.com/problems/palindrome-removal "删除回文子数组") 🔒 | [Go](../problems/palindrome-removal) | Hard |
-| <span id="1247">1247</span> | [Minimum Swaps to Make Strings Equal](https://leetcode.com/problems/minimum-swaps-to-make-strings-equal "交换字符使得字符串相同") | [Go](../problems/minimum-swaps-to-make-strings-equal) | Medium |
-| <span id="1248">1248</span> | [Count Number of Nice Subarrays](https://leetcode.com/problems/count-number-of-nice-subarrays "统计「优美子数组」") | [Go](../problems/count-number-of-nice-subarrays) | Medium |
-| <span id="1249">1249</span> | [Minimum Remove to Make Valid Parentheses](https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses "移除无效的括号") | [Go](../problems/minimum-remove-to-make-valid-parentheses) | Medium |
-| <span id="1250">1250</span> | [Check If It Is a Good Array](https://leetcode.com/problems/check-if-it-is-a-good-array "检查「好数组」") | [Go](../problems/check-if-it-is-a-good-array) | Hard |
-| <span id="1251">1251</span> | [Average Selling Price](https://leetcode.com/problems/average-selling-price "平均售价") 🔒 | [MySQL](../problems/average-selling-price) | Easy |
-| <span id="1252">1252</span> | [Cells with Odd Values in a Matrix](https://leetcode.com/problems/cells-with-odd-values-in-a-matrix "奇数值单元格的数目") | [Go](../problems/cells-with-odd-values-in-a-matrix) | Easy |
-| <span id="1253">1253</span> | [Reconstruct a 2-Row Binary Matrix](https://leetcode.com/problems/reconstruct-a-2-row-binary-matrix "重构 2 行二进制矩阵") | [Go](../problems/reconstruct-a-2-row-binary-matrix) | Medium |
-| <span id="1254">1254</span> | [Number of Closed Islands](https://leetcode.com/problems/number-of-closed-islands "统计封闭岛屿的数目") | [Go](../problems/number-of-closed-islands) | Medium |
-| <span id="1255">1255</span> | [Maximum Score Words Formed by Letters](https://leetcode.com/problems/maximum-score-words-formed-by-letters "得分最高的单词集合") | [Go](../problems/maximum-score-words-formed-by-letters) | Hard |
-| <span id="1256">1256</span> | [Encode Number](https://leetcode.com/problems/encode-number "加密数字") 🔒 | [Go](../problems/encode-number) | Medium |
-| <span id="1257">1257</span> | [Smallest Common Region](https://leetcode.com/problems/smallest-common-region "最小公共区域") 🔒 | [Go](../problems/smallest-common-region) | Medium |
-| <span id="1258">1258</span> | [Synonymous Sentences](https://leetcode.com/problems/synonymous-sentences "近义词句子") 🔒 | [Go](../problems/synonymous-sentences) | Medium |
-| <span id="1259">1259</span> | [Handshakes That Don't Cross](https://leetcode.com/problems/handshakes-that-dont-cross "不相交的握手") 🔒 | [Go](../problems/handshakes-that-dont-cross) | Hard |
-| <span id="1260">1260</span> | [Shift 2D Grid](https://leetcode.com/problems/shift-2d-grid "二维网格迁移") | [Go](../problems/shift-2d-grid) | Easy |
-| <span id="1261">1261</span> | [Find Elements in a Contaminated Binary Tree](https://leetcode.com/problems/find-elements-in-a-contaminated-binary-tree "在受污染的二叉树中查找元素") | [Go](../problems/find-elements-in-a-contaminated-binary-tree) | Medium |
-| <span id="1262">1262</span> | [Greatest Sum Divisible by Three](https://leetcode.com/problems/greatest-sum-divisible-by-three "可被三整除的最大和") | [Go](../problems/greatest-sum-divisible-by-three) | Medium |
-| <span id="1263">1263</span> | [Minimum Moves to Move a Box to Their Target Location](https://leetcode.com/problems/minimum-moves-to-move-a-box-to-their-target-location "推箱子") | [Go](../problems/minimum-moves-to-move-a-box-to-their-target-location) | Hard |
-| <span id="1264">1264</span> | [Page Recommendations](https://leetcode.com/problems/page-recommendations "页面推荐") 🔒 | [MySQL](../problems/page-recommendations) | Medium |
-| <span id="1265">1265</span> | [Print Immutable Linked List in Reverse](https://leetcode.com/problems/print-immutable-linked-list-in-reverse "逆序打印不可变链表") 🔒 | [Go](../problems/print-immutable-linked-list-in-reverse) | Medium |
-| <span id="1266">1266</span> | [Minimum Time Visiting All Points](https://leetcode.com/problems/minimum-time-visiting-all-points "访问所有点的最小时间") | [Go](../problems/minimum-time-visiting-all-points) | Easy |
-| <span id="1267">1267</span> | [Count Servers that Communicate](https://leetcode.com/problems/count-servers-that-communicate "统计参与通信的服务器") | [Go](../problems/count-servers-that-communicate) | Medium |
-| <span id="1268">1268</span> | [Search Suggestions System](https://leetcode.com/problems/search-suggestions-system "搜索推荐系统") | [Go](../problems/search-suggestions-system) | Medium |
-| <span id="1269">1269</span> | [Number of Ways to Stay in the Same Place After Some Steps](https://leetcode.com/problems/number-of-ways-to-stay-in-the-same-place-after-some-steps "停在原地的方案数") | [Go](../problems/number-of-ways-to-stay-in-the-same-place-after-some-steps) | Hard |
-| <span id="1270">1270</span> | [All People Report to the Given Manager](https://leetcode.com/problems/all-people-report-to-the-given-manager "向公司CEO汇报工作的所有人") 🔒 | [MySQL](../problems/all-people-report-to-the-given-manager) | Medium |
-| <span id="1271">1271</span> | [Hexspeak](https://leetcode.com/problems/hexspeak "十六进制魔术数字") 🔒 | [Go](../problems/hexspeak) | Easy |
-| <span id="1272">1272</span> | [Remove Interval](https://leetcode.com/problems/remove-interval "删除区间") 🔒 | [Go](../problems/remove-interval) | Medium |
-| <span id="1273">1273</span> | [Delete Tree Nodes](https://leetcode.com/problems/delete-tree-nodes "删除树节点") 🔒 | [Go](../problems/delete-tree-nodes) | Medium |
-| <span id="1274">1274</span> | [Number of Ships in a Rectangle](https://leetcode.com/problems/number-of-ships-in-a-rectangle "矩形内船只的数目") 🔒 | [Go](../problems/number-of-ships-in-a-rectangle) | Hard |
-| <span id="1275">1275</span> | [Find Winner on a Tic Tac Toe Game](https://leetcode.com/problems/find-winner-on-a-tic-tac-toe-game "找出井字棋的获胜者") | [Go](../problems/find-winner-on-a-tic-tac-toe-game) | Easy |
-| <span id="1276">1276</span> | [Number of Burgers with No Waste of Ingredients](https://leetcode.com/problems/number-of-burgers-with-no-waste-of-ingredients "不浪费原料的汉堡制作方案") | [Go](../problems/number-of-burgers-with-no-waste-of-ingredients) | Medium |
-| <span id="1277">1277</span> | [Count Square Submatrices with All Ones](https://leetcode.com/problems/count-square-submatrices-with-all-ones "统计全为 1 的正方形子矩阵") | [Go](../problems/count-square-submatrices-with-all-ones) | Medium |
-| <span id="1278">1278</span> | [Palindrome Partitioning III](https://leetcode.com/problems/palindrome-partitioning-iii "分割回文串 III") | [Go](../problems/palindrome-partitioning-iii) | Hard |
-| <span id="1279">1279</span> | [Traffic Light Controlled Intersection](https://leetcode.com/problems/traffic-light-controlled-intersection "红绿灯路口") 🔒 | [Go](../problems/traffic-light-controlled-intersection) | Easy |
-| <span id="1280">1280</span> | [Students and Examinations](https://leetcode.com/problems/students-and-examinations "学生们参加各科测试的次数") 🔒 | [MySQL](../problems/students-and-examinations) | Easy |
-| <span id="1281">1281</span> | [Subtract the Product and Sum of Digits of an Integer](https://leetcode.com/problems/subtract-the-product-and-sum-of-digits-of-an-integer "整数的各位积和之差") | [Go](../problems/subtract-the-product-and-sum-of-digits-of-an-integer) | Easy |
-| <span id="1282">1282</span> | [Group the People Given the Group Size They Belong To](https://leetcode.com/problems/group-the-people-given-the-group-size-they-belong-to "用户分组") | [Go](../problems/group-the-people-given-the-group-size-they-belong-to) | Medium |
-| <span id="1283">1283</span> | [Find the Smallest Divisor Given a Threshold](https://leetcode.com/problems/find-the-smallest-divisor-given-a-threshold "使结果不超过阈值的最小除数") | [Go](../problems/find-the-smallest-divisor-given-a-threshold) | Medium |
-| <span id="1284">1284</span> | [Minimum Number of Flips to Convert Binary Matrix to Zero Matrix](https://leetcode.com/problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix "转化为全零矩阵的最少反转次数") | [Go](../problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix) | Hard |
-| <span id="1285">1285</span> | [Find the Start and End Number of Continuous Ranges](https://leetcode.com/problems/find-the-start-and-end-number-of-continuous-ranges "找到连续区间的开始和结束数字") 🔒 | [MySQL](../problems/find-the-start-and-end-number-of-continuous-ranges) | Medium |
-| <span id="1286">1286</span> | [Iterator for Combination](https://leetcode.com/problems/iterator-for-combination "字母组合迭代器") | [Go](../problems/iterator-for-combination) | Medium |
-| <span id="1287">1287</span> | [Element Appearing More Than 25% In Sorted Array](https://leetcode.com/problems/element-appearing-more-than-25-in-sorted-array "有序数组中出现次数超过25%的元素") | [Go](../problems/element-appearing-more-than-25-in-sorted-array) | Easy |
-| <span id="1288">1288</span> | [Remove Covered Intervals](https://leetcode.com/problems/remove-covered-intervals "删除被覆盖区间") | [Go](../problems/remove-covered-intervals) | Medium |
-| <span id="1289">1289</span> | [Minimum Falling Path Sum II](https://leetcode.com/problems/minimum-falling-path-sum-ii "下降路径最小和  II") | [Go](../problems/minimum-falling-path-sum-ii) | Hard |
-| <span id="1290">1290</span> | [Convert Binary Number in a Linked List to Integer](https://leetcode.com/problems/convert-binary-number-in-a-linked-list-to-integer "二进制链表转整数") | [Go](../problems/convert-binary-number-in-a-linked-list-to-integer) | Easy |
-| <span id="1291">1291</span> | [Sequential Digits](https://leetcode.com/problems/sequential-digits "顺次数") | [Go](../problems/sequential-digits) | Medium |
-| <span id="1292">1292</span> | [Maximum Side Length of a Square with Sum Less than or Equal to Threshold](https://leetcode.com/problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold "元素和小于等于阈值的正方形的最大边长") | [Go](../problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold) | Medium |
-| <span id="1293">1293</span> | [Shortest Path in a Grid with Obstacles Elimination](https://leetcode.com/problems/shortest-path-in-a-grid-with-obstacles-elimination "网格中的最短路径") | [Go](../problems/shortest-path-in-a-grid-with-obstacles-elimination) | Hard |
-| <span id="1294">1294</span> | [Weather Type in Each Country](https://leetcode.com/problems/weather-type-in-each-country "不同国家的天气类型") 🔒 | [MySQL](../problems/weather-type-in-each-country) | Easy |
-| <span id="1295">1295</span> | [Find Numbers with Even Number of Digits](https://leetcode.com/problems/find-numbers-with-even-number-of-digits "统计位数为偶数的数字") | [Go](../problems/find-numbers-with-even-number-of-digits) | Easy |
-| <span id="1296">1296</span> | [Divide Array in Sets of K Consecutive Numbers](https://leetcode.com/problems/divide-array-in-sets-of-k-consecutive-numbers "划分数组为连续数字的集合") | [Go](../problems/divide-array-in-sets-of-k-consecutive-numbers) | Medium |
-| <span id="1297">1297</span> | [Maximum Number of Occurrences of a Substring](https://leetcode.com/problems/maximum-number-of-occurrences-of-a-substring "子串的最大出现次数") | [Go](../problems/maximum-number-of-occurrences-of-a-substring) | Medium |
-| <span id="1298">1298</span> | [Maximum Candies You Can Get from Boxes](https://leetcode.com/problems/maximum-candies-you-can-get-from-boxes "你能从盒子里获得的最大糖果数") | [Go](../problems/maximum-candies-you-can-get-from-boxes) | Hard |
-| <span id="1299">1299</span> | [Replace Elements with Greatest Element on Right Side](https://leetcode.com/problems/replace-elements-with-greatest-element-on-right-side "将每个元素替换为右侧最大元素") | [Go](../problems/replace-elements-with-greatest-element-on-right-side) | Easy |
-| <span id="1300">1300</span> | [Sum of Mutated Array Closest to Target](https://leetcode.com/problems/sum-of-mutated-array-closest-to-target "转变数组后最接近目标值的数组和") | [Go](../problems/sum-of-mutated-array-closest-to-target) | Medium |
-| <span id="1301">1301</span> | [Number of Paths with Max Score](https://leetcode.com/problems/number-of-paths-with-max-score "最大得分的路径数目") | [Go](../problems/number-of-paths-with-max-score) | Hard |
-| <span id="1302">1302</span> | [Deepest Leaves Sum](https://leetcode.com/problems/deepest-leaves-sum "层数最深叶子节点的和") | [Go](../problems/deepest-leaves-sum) | Medium |
-| <span id="1303">1303</span> | [Find the Team Size](https://leetcode.com/problems/find-the-team-size "求团队人数") 🔒 | [MySQL](../problems/find-the-team-size) | Easy |
-| <span id="1304">1304</span> | [Find N Unique Integers Sum up to Zero](https://leetcode.com/problems/find-n-unique-integers-sum-up-to-zero "和为零的N个唯一整数") | [Go](../problems/find-n-unique-integers-sum-up-to-zero) | Easy |
-| <span id="1305">1305</span> | [All Elements in Two Binary Search Trees](https://leetcode.com/problems/all-elements-in-two-binary-search-trees "两棵二叉搜索树中的所有元素") | [Go](../problems/all-elements-in-two-binary-search-trees) | Medium |
-| <span id="1306">1306</span> | [Jump Game III](https://leetcode.com/problems/jump-game-iii "跳跃游戏 III") | [Go](../problems/jump-game-iii) | Medium |
-| <span id="1307">1307</span> | [Verbal Arithmetic Puzzle](https://leetcode.com/problems/verbal-arithmetic-puzzle "口算难题") | [Go](../problems/verbal-arithmetic-puzzle) | Hard |
-| <span id="1308">1308</span> | [Running Total for Different Genders](https://leetcode.com/problems/running-total-for-different-genders "不同性别每日分数总计") 🔒 | [MySQL](../problems/running-total-for-different-genders) | Medium |
-| <span id="1309">1309</span> | [Decrypt String from Alphabet to Integer Mapping](https://leetcode.com/problems/decrypt-string-from-alphabet-to-integer-mapping "解码字母到整数映射") | [Go](../problems/decrypt-string-from-alphabet-to-integer-mapping) | Easy |
-| <span id="1310">1310</span> | [XOR Queries of a Subarray](https://leetcode.com/problems/xor-queries-of-a-subarray "子数组异或查询") | [Go](../problems/xor-queries-of-a-subarray) | Medium |
-| <span id="1311">1311</span> | [Get Watched Videos by Your Friends](https://leetcode.com/problems/get-watched-videos-by-your-friends "获取你好友已观看的视频") | [Go](../problems/get-watched-videos-by-your-friends) | Medium |
-| <span id="1312">1312</span> | [Minimum Insertion Steps to Make a String Palindrome](https://leetcode.com/problems/minimum-insertion-steps-to-make-a-string-palindrome "让字符串成为回文串的最少插入次数") | [Go](../problems/minimum-insertion-steps-to-make-a-string-palindrome) | Hard |
-| <span id="1313">1313</span> | [Decompress Run-Length Encoded List](https://leetcode.com/problems/decompress-run-length-encoded-list "解压缩编码列表") | [Go](../problems/decompress-run-length-encoded-list) | Easy |
-| <span id="1314">1314</span> | [Matrix Block Sum](https://leetcode.com/problems/matrix-block-sum "矩阵区域和") | [Go](../problems/matrix-block-sum) | Medium |
-| <span id="1315">1315</span> | [Sum of Nodes with Even-Valued Grandparent](https://leetcode.com/problems/sum-of-nodes-with-even-valued-grandparent "祖父节点值为偶数的节点和") | [Go](../problems/sum-of-nodes-with-even-valued-grandparent) | Medium |
-| <span id="1316">1316</span> | [Distinct Echo Substrings](https://leetcode.com/problems/distinct-echo-substrings "不同的循环子字符串") | [Go](../problems/distinct-echo-substrings) | Hard |
-| <span id="1317">1317</span> | [Convert Integer to the Sum of Two No-Zero Integers](https://leetcode.com/problems/convert-integer-to-the-sum-of-two-no-zero-integers "将整数转换为两个无零整数的和") | [Go](../problems/convert-integer-to-the-sum-of-two-no-zero-integers) | Easy |
-| <span id="1318">1318</span> | [Minimum Flips to Make a OR b Equal to c](https://leetcode.com/problems/minimum-flips-to-make-a-or-b-equal-to-c "或运算的最小翻转次数") | [Go](../problems/minimum-flips-to-make-a-or-b-equal-to-c) | Medium |
-| <span id="1319">1319</span> | [Number of Operations to Make Network Connected](https://leetcode.com/problems/number-of-operations-to-make-network-connected "连通网络的操作次数") | [Go](../problems/number-of-operations-to-make-network-connected) | Medium |
-| <span id="1320">1320</span> | [Minimum Distance to Type a Word Using Two Fingers](https://leetcode.com/problems/minimum-distance-to-type-a-word-using-two-fingers "二指输入的的最小距离") | [Go](../problems/minimum-distance-to-type-a-word-using-two-fingers) | Hard |
-| <span id="1321">1321</span> | [Restaurant Growth](https://leetcode.com/problems/restaurant-growth "餐馆营业额变化增长") 🔒 | [MySQL](../problems/restaurant-growth) | Medium |
-| <span id="1322">1322</span> | [Ads Performance](https://leetcode.com/problems/ads-performance "广告效果") 🔒 | [MySQL](../problems/ads-performance) | Easy |
-| <span id="1323">1323</span> | [Maximum 69 Number](https://leetcode.com/problems/maximum-69-number "6 和 9 组成的最大数字") | [Go](../problems/maximum-69-number) | Easy |
-| <span id="1324">1324</span> | [Print Words Vertically](https://leetcode.com/problems/print-words-vertically "竖直打印单词") | [Go](../problems/print-words-vertically) | Medium |
-| <span id="1325">1325</span> | [Delete Leaves With a Given Value](https://leetcode.com/problems/delete-leaves-with-a-given-value "删除给定值的叶子节点") | [Go](../problems/delete-leaves-with-a-given-value) | Medium |
-| <span id="1326">1326</span> | [Minimum Number of Taps to Open to Water a Garden](https://leetcode.com/problems/minimum-number-of-taps-to-open-to-water-a-garden "灌溉花园的最少水龙头数目") | [Go](../problems/minimum-number-of-taps-to-open-to-water-a-garden) | Hard |
-| <span id="1327">1327</span> | [List the Products Ordered in a Period](https://leetcode.com/problems/list-the-products-ordered-in-a-period "列出指定时间段内所有的下单产品") 🔒 | [MySQL](../problems/list-the-products-ordered-in-a-period) | Easy |
-| <span id="1328">1328</span> | [Break a Palindrome](https://leetcode.com/problems/break-a-palindrome "破坏回文串") | [Go](../problems/break-a-palindrome) | Medium |
-| <span id="1329">1329</span> | [Sort the Matrix Diagonally](https://leetcode.com/problems/sort-the-matrix-diagonally "将矩阵按对角线排序") | [Go](../problems/sort-the-matrix-diagonally) | Medium |
-| <span id="1330">1330</span> | [Reverse Subarray To Maximize Array Value](https://leetcode.com/problems/reverse-subarray-to-maximize-array-value "翻转子数组得到最大的数组值") | [Go](../problems/reverse-subarray-to-maximize-array-value) | Hard |
-| <span id="1331">1331</span> | [Rank Transform of an Array](https://leetcode.com/problems/rank-transform-of-an-array "数组序号转换") | [Go](../problems/rank-transform-of-an-array) | Easy |
-| <span id="1332">1332</span> | [Remove Palindromic Subsequences](https://leetcode.com/problems/remove-palindromic-subsequences "删除回文子序列") | [Go](../problems/remove-palindromic-subsequences) | Easy |
-| <span id="1333">1333</span> | [Filter Restaurants by Vegan-Friendly, Price and Distance](https://leetcode.com/problems/filter-restaurants-by-vegan-friendly-price-and-distance "餐厅过滤器") | [Go](../problems/filter-restaurants-by-vegan-friendly-price-and-distance) | Medium |
-| <span id="1334">1334</span> | [Find the City With the Smallest Number of Neighbors at a Threshold Distance](https://leetcode.com/problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance "阈值距离内邻居最少的城市") | [Go](../problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance) | Medium |
-| <span id="1335">1335</span> | [Minimum Difficulty of a Job Schedule](https://leetcode.com/problems/minimum-difficulty-of-a-job-schedule "工作计划的最低难度") | [Go](../problems/minimum-difficulty-of-a-job-schedule) | Hard |
-| <span id="1336">1336</span> | [Number of Transactions per Visit](https://leetcode.com/problems/number-of-transactions-per-visit "每次访问的交易次数") 🔒 | [MySQL](../problems/number-of-transactions-per-visit) | Hard |
-| <span id="1337">1337</span> | [The K Weakest Rows in a Matrix](https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix "矩阵中战斗力最弱的 K 行") | [Go](../problems/the-k-weakest-rows-in-a-matrix) | Easy |
-| <span id="1338">1338</span> | [Reduce Array Size to The Half](https://leetcode.com/problems/reduce-array-size-to-the-half "数组大小减半") | [Go](../problems/reduce-array-size-to-the-half) | Medium |
-| <span id="1339">1339</span> | [Maximum Product of Splitted Binary Tree](https://leetcode.com/problems/maximum-product-of-splitted-binary-tree "分裂二叉树的最大乘积") | [Go](../problems/maximum-product-of-splitted-binary-tree) | Medium |
-| <span id="1340">1340</span> | [Jump Game V](https://leetcode.com/problems/jump-game-v "跳跃游戏 V") | [Go](../problems/jump-game-v) | Hard |
-| <span id="1341">1341</span> | [Movie Rating](https://leetcode.com/problems/movie-rating "电影评分") 🔒 | [MySQL](../problems/movie-rating) | Medium |
-| <span id="1342">1342</span> | [Number of Steps to Reduce a Number to Zero](https://leetcode.com/problems/number-of-steps-to-reduce-a-number-to-zero "将数字变成 0 的操作次数") | [Go](../problems/number-of-steps-to-reduce-a-number-to-zero) | Easy |
-| <span id="1343">1343</span> | [Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold](https://leetcode.com/problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold "大小为 K 且平均值大于等于阈值的子数组数目") | [Go](../problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold) | Medium |
-| <span id="1344">1344</span> | [Angle Between Hands of a Clock](https://leetcode.com/problems/angle-between-hands-of-a-clock "时钟指针的夹角") | [Go](../problems/angle-between-hands-of-a-clock) | Medium |
-| <span id="1345">1345</span> | [Jump Game IV](https://leetcode.com/problems/jump-game-iv "跳跃游戏 IV") | [Go](../problems/jump-game-iv) | Hard |
-| <span id="1346">1346</span> | [Check If N and Its Double Exist](https://leetcode.com/problems/check-if-n-and-its-double-exist "检查整数及其两倍数是否存在") | [Go](../problems/check-if-n-and-its-double-exist) | Easy |
-| <span id="1347">1347</span> | [Minimum Number of Steps to Make Two Strings Anagram](https://leetcode.com/problems/minimum-number-of-steps-to-make-two-strings-anagram "制造字母异位词的最小步骤数") | [Go](../problems/minimum-number-of-steps-to-make-two-strings-anagram) | Medium |
-| <span id="1348">1348</span> | [Tweet Counts Per Frequency](https://leetcode.com/problems/tweet-counts-per-frequency "推文计数") | [Go](../problems/tweet-counts-per-frequency) | Medium |
-| <span id="1349">1349</span> | [Maximum Students Taking Exam](https://leetcode.com/problems/maximum-students-taking-exam "参加考试的最大学生数") | [Go](../problems/maximum-students-taking-exam) | Hard |
-| <span id="1350">1350</span> | [Students With Invalid Departments](https://leetcode.com/problems/students-with-invalid-departments "院系无效的学生") 🔒 | [MySQL](../problems/students-with-invalid-departments) | Easy |
-| <span id="1351">1351</span> | [Count Negative Numbers in a Sorted Matrix](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix "统计有序矩阵中的负数") | [Go](../problems/count-negative-numbers-in-a-sorted-matrix) | Easy |
-| <span id="1352">1352</span> | [Product of the Last K Numbers](https://leetcode.com/problems/product-of-the-last-k-numbers "最后 K 个数的乘积") | [Go](../problems/product-of-the-last-k-numbers) | Medium |
-| <span id="1353">1353</span> | [Maximum Number of Events That Can Be Attended](https://leetcode.com/problems/maximum-number-of-events-that-can-be-attended "最多可以参加的会议数目") | [Go](../problems/maximum-number-of-events-that-can-be-attended) | Medium |
-| <span id="1354">1354</span> | [Construct Target Array With Multiple Sums](https://leetcode.com/problems/construct-target-array-with-multiple-sums "多次求和构造目标数组") | [Go](../problems/construct-target-array-with-multiple-sums) | Hard |
-| <span id="1355">1355</span> | [Activity Participants](https://leetcode.com/problems/activity-participants "活动参与者") 🔒 | [MySQL](../problems/activity-participants) | Medium |
-| <span id="1356">1356</span> | [Sort Integers by The Number of 1 Bits](https://leetcode.com/problems/sort-integers-by-the-number-of-1-bits "根据数字二进制下 1 的数目排序") | [Go](../problems/sort-integers-by-the-number-of-1-bits) | Easy |
-| <span id="1357">1357</span> | [Apply Discount Every n Orders](https://leetcode.com/problems/apply-discount-every-n-orders "每隔 n 个顾客打折") | [Go](../problems/apply-discount-every-n-orders) | Medium |
-| <span id="1358">1358</span> | [Number of Substrings Containing All Three Characters](https://leetcode.com/problems/number-of-substrings-containing-all-three-characters "包含所有三种字符的子字符串数目") | [Go](../problems/number-of-substrings-containing-all-three-characters) | Medium |
-| <span id="1359">1359</span> | [Count All Valid Pickup and Delivery Options](https://leetcode.com/problems/count-all-valid-pickup-and-delivery-options "有效的快递序列数目") | [Go](../problems/count-all-valid-pickup-and-delivery-options) | Hard |
-| <span id="1360">1360</span> | [Number of Days Between Two Dates](https://leetcode.com/problems/number-of-days-between-two-dates "日期之间隔几天") | [Go](../problems/number-of-days-between-two-dates) | Easy |
-| <span id="1361">1361</span> | [Validate Binary Tree Nodes](https://leetcode.com/problems/validate-binary-tree-nodes "验证二叉树") | [Go](../problems/validate-binary-tree-nodes) | Medium |
-| <span id="1362">1362</span> | [Closest Divisors](https://leetcode.com/problems/closest-divisors "最接近的因数") | [Go](../problems/closest-divisors) | Medium |
-| <span id="1363">1363</span> | [Largest Multiple of Three](https://leetcode.com/problems/largest-multiple-of-three "形成三的最大倍数") | [Go](../problems/largest-multiple-of-three) | Hard |
-| <span id="1364">1364</span> | [Number of Trusted Contacts of a Customer](https://leetcode.com/problems/number-of-trusted-contacts-of-a-customer "顾客的可信联系人数量") 🔒 | [MySQL](../problems/number-of-trusted-contacts-of-a-customer) | Medium |
-| <span id="1365">1365</span> | [How Many Numbers Are Smaller Than the Current Number](https://leetcode.com/problems/how-many-numbers-are-smaller-than-the-current-number "有多少小于当前数字的数字") | [Go](../problems/how-many-numbers-are-smaller-than-the-current-number) | Easy |
-| <span id="1366">1366</span> | [Rank Teams by Votes](https://leetcode.com/problems/rank-teams-by-votes "通过投票对团队排名") | [Go](../problems/rank-teams-by-votes) | Medium |
-| <span id="1367">1367</span> | [Linked List in Binary Tree](https://leetcode.com/problems/linked-list-in-binary-tree "二叉树中的列表") | [Go](../problems/linked-list-in-binary-tree) | Medium |
-| <span id="1368">1368</span> | [Minimum Cost to Make at Least One Valid Path in a Grid](https://leetcode.com/problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid "使网格图至少有一条有效路径的最小代价") | [Go](../problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid) | Hard |
-| <span id="1369">1369</span> | [Get the Second Most Recent Activity](https://leetcode.com/problems/get-the-second-most-recent-activity "获取最近第二次的活动") 🔒 | [MySQL](../problems/get-the-second-most-recent-activity) | Hard |
-| <span id="1370">1370</span> | [Increasing Decreasing String](https://leetcode.com/problems/increasing-decreasing-string "上升下降字符串") | [Go](../problems/increasing-decreasing-string) | Easy |
-| <span id="1371">1371</span> | [Find the Longest Substring Containing Vowels in Even Counts](https://leetcode.com/problems/find-the-longest-substring-containing-vowels-in-even-counts "每个元音包含偶数次的最长子字符串") | [Go](../problems/find-the-longest-substring-containing-vowels-in-even-counts) | Medium |
-| <span id="1372">1372</span> | [Longest ZigZag Path in a Binary Tree](https://leetcode.com/problems/longest-zigzag-path-in-a-binary-tree "二叉树中的最长交错路径") | [Go](../problems/longest-zigzag-path-in-a-binary-tree) | Medium |
-| <span id="1373">1373</span> | [Maximum Sum BST in Binary Tree](https://leetcode.com/problems/maximum-sum-bst-in-binary-tree "二叉搜索子树的最大键值和") | [Go](../problems/maximum-sum-bst-in-binary-tree) | Hard |
-| <span id="1374">1374</span> | [Generate a String With Characters That Have Odd Counts](https://leetcode.com/problems/generate-a-string-with-characters-that-have-odd-counts "生成每种字符都是奇数个的字符串") | [Go](../problems/generate-a-string-with-characters-that-have-odd-counts) | Easy |
-| <span id="1375">1375</span> | [Number of Times Binary String Is Prefix-Aligned](https://leetcode.com/problems/number-of-times-binary-string-is-prefix-aligned "二进制字符串前缀一致的次数") | [Go](../problems/number-of-times-binary-string-is-prefix-aligned) | Medium |
-| <span id="1376">1376</span> | [Time Needed to Inform All Employees](https://leetcode.com/problems/time-needed-to-inform-all-employees "通知所有员工所需的时间") | [Go](../problems/time-needed-to-inform-all-employees) | Medium |
-| <span id="1377">1377</span> | [Frog Position After T Seconds](https://leetcode.com/problems/frog-position-after-t-seconds "T 秒后青蛙的位置") | [Go](../problems/frog-position-after-t-seconds) | Hard |
-| <span id="1378">1378</span> | [Replace Employee ID With The Unique Identifier](https://leetcode.com/problems/replace-employee-id-with-the-unique-identifier "使用唯一标识码替换员工ID") 🔒 | [MySQL](../problems/replace-employee-id-with-the-unique-identifier) | Easy |
-| <span id="1379">1379</span> | [Find a Corresponding Node of a Binary Tree in a Clone of That Tree](https://leetcode.com/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree "找出克隆二叉树中的相同节点") | [Go](../problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree) | Medium |
-| <span id="1380">1380</span> | [Lucky Numbers in a Matrix](https://leetcode.com/problems/lucky-numbers-in-a-matrix "矩阵中的幸运数") | [Go](../problems/lucky-numbers-in-a-matrix) | Easy |
-| <span id="1381">1381</span> | [Design a Stack With Increment Operation](https://leetcode.com/problems/design-a-stack-with-increment-operation "设计一个支持增量操作的栈") | [Go](../problems/design-a-stack-with-increment-operation) | Medium |
-| <span id="1382">1382</span> | [Balance a Binary Search Tree](https://leetcode.com/problems/balance-a-binary-search-tree "将二叉搜索树变平衡") | [Go](../problems/balance-a-binary-search-tree) | Medium |
-| <span id="1383">1383</span> | [Maximum Performance of a Team](https://leetcode.com/problems/maximum-performance-of-a-team "最大的团队表现值") | [Go](../problems/maximum-performance-of-a-team) | Hard |
-| <span id="1384">1384</span> | [Total Sales Amount by Year](https://leetcode.com/problems/total-sales-amount-by-year "按年度列出销售总额") 🔒 | [MySQL](../problems/total-sales-amount-by-year) | Hard |
-| <span id="1385">1385</span> | [Find the Distance Value Between Two Arrays](https://leetcode.com/problems/find-the-distance-value-between-two-arrays "两个数组间的距离值") | [Go](../problems/find-the-distance-value-between-two-arrays) | Easy |
-| <span id="1386">1386</span> | [Cinema Seat Allocation](https://leetcode.com/problems/cinema-seat-allocation "安排电影院座位") | [Go](../problems/cinema-seat-allocation) | Medium |
-| <span id="1387">1387</span> | [Sort Integers by The Power Value](https://leetcode.com/problems/sort-integers-by-the-power-value "将整数按权重排序") | [Go](../problems/sort-integers-by-the-power-value) | Medium |
-| <span id="1388">1388</span> | [Pizza With 3n Slices](https://leetcode.com/problems/pizza-with-3n-slices "3n 块披萨") | [Go](../problems/pizza-with-3n-slices) | Hard |
-| <span id="1389">1389</span> | [Create Target Array in the Given Order](https://leetcode.com/problems/create-target-array-in-the-given-order "按既定顺序创建目标数组") | [Go](../problems/create-target-array-in-the-given-order) | Easy |
-| <span id="1390">1390</span> | [Four Divisors](https://leetcode.com/problems/four-divisors "四因数") | [Go](../problems/four-divisors) | Medium |
-| <span id="1391">1391</span> | [Check if There is a Valid Path in a Grid](https://leetcode.com/problems/check-if-there-is-a-valid-path-in-a-grid "检查网格中是否存在有效路径") | [Go](../problems/check-if-there-is-a-valid-path-in-a-grid) | Medium |
-| <span id="1392">1392</span> | [Longest Happy Prefix](https://leetcode.com/problems/longest-happy-prefix "最长快乐前缀") | [Go](../problems/longest-happy-prefix) | Hard |
-| <span id="1393">1393</span> | [Capital Gain/Loss](https://leetcode.com/problems/capital-gainloss "股票的资本损益") 🔒 | [MySQL](../problems/capital-gainloss) | Medium |
-| <span id="1394">1394</span> | [Find Lucky Integer in an Array](https://leetcode.com/problems/find-lucky-integer-in-an-array "找出数组中的幸运数") | [Go](../problems/find-lucky-integer-in-an-array) | Easy |
-| <span id="1395">1395</span> | [Count Number of Teams](https://leetcode.com/problems/count-number-of-teams "统计作战单位数") | [Go](../problems/count-number-of-teams) | Medium |
-| <span id="1396">1396</span> | [Design Underground System](https://leetcode.com/problems/design-underground-system "设计地铁系统") | [Go](../problems/design-underground-system) | Medium |
-| <span id="1397">1397</span> | [Find All Good Strings](https://leetcode.com/problems/find-all-good-strings "找到所有好字符串") | [Go](../problems/find-all-good-strings) | Hard |
-| <span id="1398">1398</span> | [Customers Who Bought Products A and B but Not C](https://leetcode.com/problems/customers-who-bought-products-a-and-b-but-not-c "购买了产品 A 和产品 B 却没有购买产品 C 的顾客") 🔒 | [MySQL](../problems/customers-who-bought-products-a-and-b-but-not-c) | Medium |
-| <span id="1399">1399</span> | [Count Largest Group](https://leetcode.com/problems/count-largest-group "统计最大组的数目") | [Go](../problems/count-largest-group) | Easy |
-| <span id="1400">1400</span> | [Construct K Palindrome Strings](https://leetcode.com/problems/construct-k-palindrome-strings "构造 K 个回文字符串") | [Go](../problems/construct-k-palindrome-strings) | Medium |
-| <span id="1401">1401</span> | [Circle and Rectangle Overlapping](https://leetcode.com/problems/circle-and-rectangle-overlapping "圆和矩形是否有重叠") | [Go](../problems/circle-and-rectangle-overlapping) | Medium |
-| <span id="1402">1402</span> | [Reducing Dishes](https://leetcode.com/problems/reducing-dishes "做菜顺序") | [Go](../problems/reducing-dishes) | Hard |
-| <span id="1403">1403</span> | [Minimum Subsequence in Non-Increasing Order](https://leetcode.com/problems/minimum-subsequence-in-non-increasing-order "非递增顺序的最小子序列") | [Go](../problems/minimum-subsequence-in-non-increasing-order) | Easy |
-| <span id="1404">1404</span> | [Number of Steps to Reduce a Number in Binary Representation to One](https://leetcode.com/problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one "将二进制表示减到 1 的步骤数") | [Go](../problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one) | Medium |
-| <span id="1405">1405</span> | [Longest Happy String](https://leetcode.com/problems/longest-happy-string "最长快乐字符串") | [Go](../problems/longest-happy-string) | Medium |
-| <span id="1406">1406</span> | [Stone Game III](https://leetcode.com/problems/stone-game-iii "石子游戏 III") | [Go](../problems/stone-game-iii) | Hard |
-| <span id="1407">1407</span> | [Top Travellers](https://leetcode.com/problems/top-travellers "排名靠前的旅行者") 🔒 | [MySQL](../problems/top-travellers) | Easy |
-| <span id="1408">1408</span> | [String Matching in an Array](https://leetcode.com/problems/string-matching-in-an-array "数组中的字符串匹配") | [Go](../problems/string-matching-in-an-array) | Easy |
-| <span id="1409">1409</span> | [Queries on a Permutation With Key](https://leetcode.com/problems/queries-on-a-permutation-with-key "查询带键的排列") | [Go](../problems/queries-on-a-permutation-with-key) | Medium |
-| <span id="1410">1410</span> | [HTML Entity Parser](https://leetcode.com/problems/html-entity-parser "HTML 实体解析器") | [Go](../problems/html-entity-parser) | Medium |
-| <span id="1411">1411</span> | [Number of Ways to Paint N × 3 Grid](https://leetcode.com/problems/number-of-ways-to-paint-n-3-grid "给 N x 3 网格图涂色的方案数") | [Go](../problems/number-of-ways-to-paint-n-3-grid) | Hard |
-| <span id="1412">1412</span> | [Find the Quiet Students in All Exams](https://leetcode.com/problems/find-the-quiet-students-in-all-exams "查找成绩处于中游的学生") 🔒 | [MySQL](../problems/find-the-quiet-students-in-all-exams) | Hard |
-| <span id="1413">1413</span> | [Minimum Value to Get Positive Step by Step Sum](https://leetcode.com/problems/minimum-value-to-get-positive-step-by-step-sum "逐步求和得到正数的最小值") | [Go](../problems/minimum-value-to-get-positive-step-by-step-sum) | Easy |
-| <span id="1414">1414</span> | [Find the Minimum Number of Fibonacci Numbers Whose Sum Is K](https://leetcode.com/problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k "和为 K 的最少斐波那契数字数目") | [Go](../problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k) | Medium |
-| <span id="1415">1415</span> | [The k-th Lexicographical String of All Happy Strings of Length n](https://leetcode.com/problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n "长度为 n 的开心字符串中字典序第 k 小的字符串") | [Go](../problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n) | Medium |
-| <span id="1416">1416</span> | [Restore The Array](https://leetcode.com/problems/restore-the-array "恢复数组") | [Go](../problems/restore-the-array) | Hard |
-| <span id="1417">1417</span> | [Reformat The String](https://leetcode.com/problems/reformat-the-string "重新格式化字符串") | [Go](../problems/reformat-the-string) | Easy |
-| <span id="1418">1418</span> | [Display Table of Food Orders in a Restaurant](https://leetcode.com/problems/display-table-of-food-orders-in-a-restaurant "点菜展示表") | [Go](../problems/display-table-of-food-orders-in-a-restaurant) | Medium |
-| <span id="1419">1419</span> | [Minimum Number of Frogs Croaking](https://leetcode.com/problems/minimum-number-of-frogs-croaking "数青蛙") | [Go](../problems/minimum-number-of-frogs-croaking) | Medium |
-| <span id="1420">1420</span> | [Build Array Where You Can Find The Maximum Exactly K Comparisons](https://leetcode.com/problems/build-array-where-you-can-find-the-maximum-exactly-k-comparisons "生成数组") | [Go](../problems/build-array-where-you-can-find-the-maximum-exactly-k-comparisons) | Hard |
-| <span id="1421">1421</span> | [NPV Queries](https://leetcode.com/problems/npv-queries "净现值查询") 🔒 | [MySQL](../problems/npv-queries) | Easy |
-| <span id="1422">1422</span> | [Maximum Score After Splitting a String](https://leetcode.com/problems/maximum-score-after-splitting-a-string "分割字符串的最大得分") | [Go](../problems/maximum-score-after-splitting-a-string) | Easy |
-| <span id="1423">1423</span> | [Maximum Points You Can Obtain from Cards](https://leetcode.com/problems/maximum-points-you-can-obtain-from-cards "可获得的最大点数") | [Go](../problems/maximum-points-you-can-obtain-from-cards) | Medium |
-| <span id="1424">1424</span> | [Diagonal Traverse II](https://leetcode.com/problems/diagonal-traverse-ii "对角线遍历 II") | [Go](../problems/diagonal-traverse-ii) | Medium |
-| <span id="1425">1425</span> | [Constrained Subsequence Sum](https://leetcode.com/problems/constrained-subsequence-sum "带限制的子序列和") | [Go](../problems/constrained-subsequence-sum) | Hard |
-| <span id="1426">1426</span> | [Counting Elements](https://leetcode.com/problems/counting-elements "数元素") 🔒 | [Go](../problems/counting-elements) | Easy |
-| <span id="1427">1427</span> | [Perform String Shifts](https://leetcode.com/problems/perform-string-shifts "字符串的左右移") 🔒 | [Go](../problems/perform-string-shifts) | Easy |
-| <span id="1428">1428</span> | [Leftmost Column with at Least a One](https://leetcode.com/problems/leftmost-column-with-at-least-a-one "至少有一个 1 的最左端列") 🔒 | [Go](../problems/leftmost-column-with-at-least-a-one) | Medium |
-| <span id="1429">1429</span> | [First Unique Number](https://leetcode.com/problems/first-unique-number "第一个唯一数字") 🔒 | [Go](../problems/first-unique-number) | Medium |
-| <span id="1430">1430</span> | [Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree](https://leetcode.com/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree "判断给定的序列是否是二叉树从根到叶的路径") 🔒 | [Go](../problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree) | Medium |
-| <span id="1431">1431</span> | [Kids With the Greatest Number of Candies](https://leetcode.com/problems/kids-with-the-greatest-number-of-candies "拥有最多糖果的孩子") | [Go](../problems/kids-with-the-greatest-number-of-candies) | Easy |
-| <span id="1432">1432</span> | [Max Difference You Can Get From Changing an Integer](https://leetcode.com/problems/max-difference-you-can-get-from-changing-an-integer "改变一个整数能得到的最大差值") | [Go](../problems/max-difference-you-can-get-from-changing-an-integer) | Medium |
-| <span id="1433">1433</span> | [Check If a String Can Break Another String](https://leetcode.com/problems/check-if-a-string-can-break-another-string "检查一个字符串是否可以打破另一个字符串") | [Go](../problems/check-if-a-string-can-break-another-string) | Medium |
-| <span id="1434">1434</span> | [Number of Ways to Wear Different Hats to Each Other](https://leetcode.com/problems/number-of-ways-to-wear-different-hats-to-each-other "每个人戴不同帽子的方案数") | [Go](../problems/number-of-ways-to-wear-different-hats-to-each-other) | Hard |
-| <span id="1435">1435</span> | [Create a Session Bar Chart](https://leetcode.com/problems/create-a-session-bar-chart "制作会话柱状图") 🔒 | [MySQL](../problems/create-a-session-bar-chart) | Easy |
-| <span id="1436">1436</span> | [Destination City](https://leetcode.com/problems/destination-city "旅行终点站") | [Go](../problems/destination-city) | Easy |
-| <span id="1437">1437</span> | [Check If All 1's Are at Least Length K Places Away](https://leetcode.com/problems/check-if-all-1s-are-at-least-length-k-places-away "是否所有 1 都至少相隔 k 个元素") | [Go](../problems/check-if-all-1s-are-at-least-length-k-places-away) | Easy |
-| <span id="1438">1438</span> | [Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit](https://leetcode.com/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit "绝对差不超过限制的最长连续子数组") | [Go](../problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit) | Medium |
-| <span id="1439">1439</span> | [Find the Kth Smallest Sum of a Matrix With Sorted Rows](https://leetcode.com/problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows "有序矩阵中的第 k 个最小数组和") | [Go](../problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows) | Hard |
-| <span id="1440">1440</span> | [Evaluate Boolean Expression](https://leetcode.com/problems/evaluate-boolean-expression "计算布尔表达式的值") 🔒 | [MySQL](../problems/evaluate-boolean-expression) | Medium |
-| <span id="1441">1441</span> | [Build an Array With Stack Operations](https://leetcode.com/problems/build-an-array-with-stack-operations "用栈操作构建数组") | [Go](../problems/build-an-array-with-stack-operations) | Easy |
-| <span id="1442">1442</span> | [Count Triplets That Can Form Two Arrays of Equal XOR](https://leetcode.com/problems/count-triplets-that-can-form-two-arrays-of-equal-xor "形成两个异或相等数组的三元组数目") | [Go](../problems/count-triplets-that-can-form-two-arrays-of-equal-xor) | Medium |
-| <span id="1443">1443</span> | [Minimum Time to Collect All Apples in a Tree](https://leetcode.com/problems/minimum-time-to-collect-all-apples-in-a-tree "收集树上所有苹果的最少时间") | [Go](../problems/minimum-time-to-collect-all-apples-in-a-tree) | Medium |
-| <span id="1444">1444</span> | [Number of Ways of Cutting a Pizza](https://leetcode.com/problems/number-of-ways-of-cutting-a-pizza "切披萨的方案数") | [Go](../problems/number-of-ways-of-cutting-a-pizza) | Hard |
-| <span id="1445">1445</span> | [Apples & Oranges](https://leetcode.com/problems/apples-oranges "苹果和桔子") 🔒 | [MySQL](../problems/apples-oranges) | Medium |
-| <span id="1446">1446</span> | [Consecutive Characters](https://leetcode.com/problems/consecutive-characters "连续字符") | [Go](../problems/consecutive-characters) | Easy |
-| <span id="1447">1447</span> | [Simplified Fractions](https://leetcode.com/problems/simplified-fractions "最简分数") | [Go](../problems/simplified-fractions) | Medium |
-| <span id="1448">1448</span> | [Count Good Nodes in Binary Tree](https://leetcode.com/problems/count-good-nodes-in-binary-tree "统计二叉树中好节点的数目") | [Go](../problems/count-good-nodes-in-binary-tree) | Medium |
-| <span id="1449">1449</span> | [Form Largest Integer With Digits That Add up to Target](https://leetcode.com/problems/form-largest-integer-with-digits-that-add-up-to-target "数位成本和为目标值的最大数字") | [Go](../problems/form-largest-integer-with-digits-that-add-up-to-target) | Hard |
-| <span id="1450">1450</span> | [Number of Students Doing Homework at a Given Time](https://leetcode.com/problems/number-of-students-doing-homework-at-a-given-time "在既定时间做作业的学生人数") | [Go](../problems/number-of-students-doing-homework-at-a-given-time) | Easy |
-| <span id="1451">1451</span> | [Rearrange Words in a Sentence](https://leetcode.com/problems/rearrange-words-in-a-sentence "重新排列句子中的单词") | [Go](../problems/rearrange-words-in-a-sentence) | Medium |
-| <span id="1452">1452</span> | [People Whose List of Favorite Companies Is Not a Subset of Another List](https://leetcode.com/problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list "收藏清单") | [Go](../problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list) | Medium |
-| <span id="1453">1453</span> | [Maximum Number of Darts Inside of a Circular Dartboard](https://leetcode.com/problems/maximum-number-of-darts-inside-of-a-circular-dartboard "圆形靶内的最大飞镖数量") | [Go](../problems/maximum-number-of-darts-inside-of-a-circular-dartboard) | Hard |
-| <span id="1454">1454</span> | [Active Users](https://leetcode.com/problems/active-users "活跃用户") 🔒 | [MySQL](../problems/active-users) | Medium |
-| <span id="1455">1455</span> | [Check If a Word Occurs As a Prefix of Any Word in a Sentence](https://leetcode.com/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence "检查单词是否为句中其他单词的前缀") | [Go](../problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence) | Easy |
-| <span id="1456">1456</span> | [Maximum Number of Vowels in a Substring of Given Length](https://leetcode.com/problems/maximum-number-of-vowels-in-a-substring-of-given-length "定长子串中元音的最大数目") | [Go](../problems/maximum-number-of-vowels-in-a-substring-of-given-length) | Medium |
-| <span id="1457">1457</span> | [Pseudo-Palindromic Paths in a Binary Tree](https://leetcode.com/problems/pseudo-palindromic-paths-in-a-binary-tree "二叉树中的伪回文路径") | [Go](../problems/pseudo-palindromic-paths-in-a-binary-tree) | Medium |
-| <span id="1458">1458</span> | [Max Dot Product of Two Subsequences](https://leetcode.com/problems/max-dot-product-of-two-subsequences "两个子序列的最大点积") | [Go](../problems/max-dot-product-of-two-subsequences) | Hard |
-| <span id="1459">1459</span> | [Rectangles Area](https://leetcode.com/problems/rectangles-area "矩形面积") 🔒 | [MySQL](../problems/rectangles-area) | Medium |
-| <span id="1460">1460</span> | [Make Two Arrays Equal by Reversing Sub-arrays](https://leetcode.com/problems/make-two-arrays-equal-by-reversing-sub-arrays "通过翻转子数组使两个数组相等") | [Go](../problems/make-two-arrays-equal-by-reversing-sub-arrays) | Easy |
-| <span id="1461">1461</span> | [Check If a String Contains All Binary Codes of Size K](https://leetcode.com/problems/check-if-a-string-contains-all-binary-codes-of-size-k "检查一个字符串是否包含所有长度为 K 的二进制子串") | [Go](../problems/check-if-a-string-contains-all-binary-codes-of-size-k) | Medium |
-| <span id="1462">1462</span> | [Course Schedule IV](https://leetcode.com/problems/course-schedule-iv "课程表 IV") | [Go](../problems/course-schedule-iv) | Medium |
-| <span id="1463">1463</span> | [Cherry Pickup II](https://leetcode.com/problems/cherry-pickup-ii "摘樱桃 II") | [Go](../problems/cherry-pickup-ii) | Hard |
-| <span id="1464">1464</span> | [Maximum Product of Two Elements in an Array](https://leetcode.com/problems/maximum-product-of-two-elements-in-an-array "数组中两元素的最大乘积") | [Go](../problems/maximum-product-of-two-elements-in-an-array) | Easy |
-| <span id="1465">1465</span> | [Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts](https://leetcode.com/problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts "切割后面积最大的蛋糕") | [Go](../problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts) | Medium |
-| <span id="1466">1466</span> | [Reorder Routes to Make All Paths Lead to the City Zero](https://leetcode.com/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero "重新规划路线") | [Go](../problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero) | Medium |
-| <span id="1467">1467</span> | [Probability of a Two Boxes Having The Same Number of Distinct Balls](https://leetcode.com/problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls "两个盒子中球的颜色数相同的概率") | [Go](../problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls) | Hard |
-| <span id="1468">1468</span> | [Calculate Salaries](https://leetcode.com/problems/calculate-salaries "计算税后工资") 🔒 | [MySQL](../problems/calculate-salaries) | Medium |
-| <span id="1469">1469</span> | [Find All The Lonely Nodes](https://leetcode.com/problems/find-all-the-lonely-nodes "寻找所有的独生节点") 🔒 | [Go](../problems/find-all-the-lonely-nodes) | Easy |
-| <span id="1470">1470</span> | [Shuffle the Array](https://leetcode.com/problems/shuffle-the-array "重新排列数组") | [Go](../problems/shuffle-the-array) | Easy |
-| <span id="1471">1471</span> | [The k Strongest Values in an Array](https://leetcode.com/problems/the-k-strongest-values-in-an-array "数组中的 k 个最强值") | [Go](../problems/the-k-strongest-values-in-an-array) | Medium |
-| <span id="1472">1472</span> | [Design Browser History](https://leetcode.com/problems/design-browser-history "设计浏览器历史记录") | [Go](../problems/design-browser-history) | Medium |
-| <span id="1473">1473</span> | [Paint House III](https://leetcode.com/problems/paint-house-iii "粉刷房子 III") | [Go](../problems/paint-house-iii) | Hard |
-| <span id="1474">1474</span> | [Delete N Nodes After M Nodes of a Linked List](https://leetcode.com/problems/delete-n-nodes-after-m-nodes-of-a-linked-list "删除链表 M 个节点之后的 N 个节点") 🔒 | [Go](../problems/delete-n-nodes-after-m-nodes-of-a-linked-list) | Easy |
-| <span id="1475">1475</span> | [Final Prices With a Special Discount in a Shop](https://leetcode.com/problems/final-prices-with-a-special-discount-in-a-shop "商品折扣后的最终价格") | [Go](../problems/final-prices-with-a-special-discount-in-a-shop) | Easy |
-| <span id="1476">1476</span> | [Subrectangle Queries](https://leetcode.com/problems/subrectangle-queries "子矩形查询") | [Go](../problems/subrectangle-queries) | Medium |
-| <span id="1477">1477</span> | [Find Two Non-overlapping Sub-arrays Each With Target Sum](https://leetcode.com/problems/find-two-non-overlapping-sub-arrays-each-with-target-sum "找两个和为目标值且不重叠的子数组") | [Go](../problems/find-two-non-overlapping-sub-arrays-each-with-target-sum) | Medium |
-| <span id="1478">1478</span> | [Allocate Mailboxes](https://leetcode.com/problems/allocate-mailboxes "安排邮筒") | [Go](../problems/allocate-mailboxes) | Hard |
-| <span id="1479">1479</span> | [Sales by Day of the Week](https://leetcode.com/problems/sales-by-day-of-the-week "周内每天的销售情况") 🔒 | [MySQL](../problems/sales-by-day-of-the-week) | Hard |
-| <span id="1480">1480</span> | [Running Sum of 1d Array](https://leetcode.com/problems/running-sum-of-1d-array "一维数组的动态和") | [Go](../problems/running-sum-of-1d-array) | Easy |
-| <span id="1481">1481</span> | [Least Number of Unique Integers after K Removals](https://leetcode.com/problems/least-number-of-unique-integers-after-k-removals "不同整数的最少数目") | [Go](../problems/least-number-of-unique-integers-after-k-removals) | Medium |
-| <span id="1482">1482</span> | [Minimum Number of Days to Make m Bouquets](https://leetcode.com/problems/minimum-number-of-days-to-make-m-bouquets "制作 m 束花所需的最少天数") | [Go](../problems/minimum-number-of-days-to-make-m-bouquets) | Medium |
-| <span id="1483">1483</span> | [Kth Ancestor of a Tree Node](https://leetcode.com/problems/kth-ancestor-of-a-tree-node "树节点的第 K 个祖先") | [Go](../problems/kth-ancestor-of-a-tree-node) | Hard |
-| <span id="1484">1484</span> | [Group Sold Products By The Date](https://leetcode.com/problems/group-sold-products-by-the-date "按日期分组销售产品") 🔒 | [MySQL](../problems/group-sold-products-by-the-date) | Easy |
-| <span id="1485">1485</span> | [Clone Binary Tree With Random Pointer](https://leetcode.com/problems/clone-binary-tree-with-random-pointer "克隆含随机指针的二叉树") 🔒 | [Go](../problems/clone-binary-tree-with-random-pointer) | Medium |
-| <span id="1486">1486</span> | [XOR Operation in an Array](https://leetcode.com/problems/xor-operation-in-an-array "数组异或操作") | [Go](../problems/xor-operation-in-an-array) | Easy |
-| <span id="1487">1487</span> | [Making File Names Unique](https://leetcode.com/problems/making-file-names-unique "保证文件名唯一") | [Go](../problems/making-file-names-unique) | Medium |
-| <span id="1488">1488</span> | [Avoid Flood in The City](https://leetcode.com/problems/avoid-flood-in-the-city "避免洪水泛滥") | [Go](../problems/avoid-flood-in-the-city) | Medium |
-| <span id="1489">1489</span> | [Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree](https://leetcode.com/problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree "找到最小生成树里的关键边和伪关键边") | [Go](../problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree) | Hard |
-| <span id="1490">1490</span> | [Clone N-ary Tree](https://leetcode.com/problems/clone-n-ary-tree "克隆 N 叉树") 🔒 | [Go](../problems/clone-n-ary-tree) | Medium |
-| <span id="1491">1491</span> | [Average Salary Excluding the Minimum and Maximum Salary](https://leetcode.com/problems/average-salary-excluding-the-minimum-and-maximum-salary "去掉最低工资和最高工资后的工资平均值") | [Go](../problems/average-salary-excluding-the-minimum-and-maximum-salary) | Easy |
-| <span id="1492">1492</span> | [The kth Factor of n](https://leetcode.com/problems/the-kth-factor-of-n "n 的第 k 个因子") | [Go](../problems/the-kth-factor-of-n) | Medium |
-| <span id="1493">1493</span> | [Longest Subarray of 1's After Deleting One Element](https://leetcode.com/problems/longest-subarray-of-1s-after-deleting-one-element "删掉一个元素以后全为 1 的最长子数组") | [Go](../problems/longest-subarray-of-1s-after-deleting-one-element) | Medium |
-| <span id="1494">1494</span> | [Parallel Courses II](https://leetcode.com/problems/parallel-courses-ii "并行课程 II") | [Go](../problems/parallel-courses-ii) | Hard |
-| <span id="1495">1495</span> | [Friendly Movies Streamed Last Month](https://leetcode.com/problems/friendly-movies-streamed-last-month "上月播放的儿童适宜电影") 🔒 | [MySQL](../problems/friendly-movies-streamed-last-month) | Easy |
-| <span id="1496">1496</span> | [Path Crossing](https://leetcode.com/problems/path-crossing "判断路径是否相交") | [Go](../problems/path-crossing) | Easy |
-| <span id="1497">1497</span> | [Check If Array Pairs Are Divisible by k](https://leetcode.com/problems/check-if-array-pairs-are-divisible-by-k "检查数组对是否可以被 k 整除") | [Go](../problems/check-if-array-pairs-are-divisible-by-k) | Medium |
-| <span id="1498">1498</span> | [Number of Subsequences That Satisfy the Given Sum Condition](https://leetcode.com/problems/number-of-subsequences-that-satisfy-the-given-sum-condition "满足条件的子序列数目") | [Go](../problems/number-of-subsequences-that-satisfy-the-given-sum-condition) | Medium |
-| <span id="1499">1499</span> | [Max Value of Equation](https://leetcode.com/problems/max-value-of-equation "满足不等式的最大值") | [Go](../problems/max-value-of-equation) | Hard |
-| <span id="1500">1500</span> | [Design a File Sharing System](https://leetcode.com/problems/design-a-file-sharing-system "设计文件分享系统") 🔒 | [Go](../problems/design-a-file-sharing-system) | Medium |
diff --git a/readme/1501-1800.md b/readme/1501-1800.md
deleted file mode 100644
index 85463f503..000000000
--- a/readme/1501-1800.md
+++ /dev/null
@@ -1,388 +0,0 @@
-<!--|This file generated by command(leetcode readme); DO NOT EDIT.         |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-# [LeetCode](https://awesee.github.io/leetcode)
-LeetCode Problems' Solutions
-[[力扣](https://awesee.github.io/categories/leetcode/) ∙ [话题分类](https://github.com/awesee/leetcode/blob/master/tag/README.md)]
-
-[![Go](https://github.com/awesee/leetcode/workflows/Go/badge.svg)](https://github.com/awesee/leetcode/actions)
-[![codecov](https://codecov.io/gh/awesee/leetcode/branch/master/graph/badge.svg)](https://codecov.io/gh/awesee/leetcode)
-[![Go Report Card](https://goreportcard.com/badge/github.com/awesee/leetcode)](https://goreportcard.com/report/github.com/awesee/leetcode)
-[![GitHub contributors](https://img.shields.io/github/contributors/awesee/leetcode.svg)](https://github.com/awesee/leetcode/graphs/contributors)
-[![license](https://img.shields.io/github/license/awesee/leetcode.svg)](https://github.com/awesee/leetcode/blob/master/LICENSE)
-[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fawesee%2Fleetcode.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fawesee%2Fleetcode?ref=badge_shield)
-[![Join the chat](https://badges.gitter.im/awesee/leetcode.svg)](https://gitter.im/awesee/leetcode?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-
-<table><thead>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#1">[1-50]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#51">[51-100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#101">[101-150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#151">[151-200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#201">[201-250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#251">[251-300]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#301">[301-350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#351">[351-400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#401">[401-450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#451">[451-500]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#501">[501-550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#551">[551-600]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#601">[601-650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#651">[651-700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#701">[701-750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#751">[751-800]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#801">[801-850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#851">[851-900]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#901">[901-950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#951">[951-1000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1001">[1001-1050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1051">[1051-1100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1101">[1101-1150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1151">[1151-1200]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1201">[1201-1250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1251">[1251-1300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1301">[1301-1350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1351">[1351-1400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1401">[1401-1450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1451">[1451-1500]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1501">[1501-1550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1551">[1551-1600]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1601">[1601-1650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1651">[1651-1700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1701">[1701-1750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1751">[1751-1800]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1850">[1801-1850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1900">[1851-1900]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1950">[1901-1950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2000">[1951-2000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2050">[2001-2050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2100">[2051-2100]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2150">[2101-2150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2200">[2151-2200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2250">[2201-2250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2300">[2251-2300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2350">[2301-2350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2400">[2351-2400]</a></th>
-</tr>
-</thead></table>
-
-| # | Title | Solution | Difficulty |
-| :-: | - | - | :-: |
-| <span id="1501">1501</span> | [Countries You Can Safely Invest In](https://leetcode.com/problems/countries-you-can-safely-invest-in "可以放心投资的国家") 🔒 | [MySQL](../problems/countries-you-can-safely-invest-in) | Medium |
-| <span id="1502">1502</span> | [Can Make Arithmetic Progression From Sequence](https://leetcode.com/problems/can-make-arithmetic-progression-from-sequence "判断能否形成等差数列") | [Go](../problems/can-make-arithmetic-progression-from-sequence) | Easy |
-| <span id="1503">1503</span> | [Last Moment Before All Ants Fall Out of a Plank](https://leetcode.com/problems/last-moment-before-all-ants-fall-out-of-a-plank "所有蚂蚁掉下来前的最后一刻") | [Go](../problems/last-moment-before-all-ants-fall-out-of-a-plank) | Medium |
-| <span id="1504">1504</span> | [Count Submatrices With All Ones](https://leetcode.com/problems/count-submatrices-with-all-ones "统计全 1 子矩形") | [Go](../problems/count-submatrices-with-all-ones) | Medium |
-| <span id="1505">1505</span> | [Minimum Possible Integer After at Most K Adjacent Swaps On Digits](https://leetcode.com/problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits "最多 K 次交换相邻数位后得到的最小整数") | [Go](../problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits) | Hard |
-| <span id="1506">1506</span> | [Find Root of N-Ary Tree](https://leetcode.com/problems/find-root-of-n-ary-tree "找到 N 叉树的根节点") 🔒 | [Go](../problems/find-root-of-n-ary-tree) | Medium |
-| <span id="1507">1507</span> | [Reformat Date](https://leetcode.com/problems/reformat-date "转变日期格式") | [Go](../problems/reformat-date) | Easy |
-| <span id="1508">1508</span> | [Range Sum of Sorted Subarray Sums](https://leetcode.com/problems/range-sum-of-sorted-subarray-sums "子数组和排序后的区间和") | [Go](../problems/range-sum-of-sorted-subarray-sums) | Medium |
-| <span id="1509">1509</span> | [Minimum Difference Between Largest and Smallest Value in Three Moves](https://leetcode.com/problems/minimum-difference-between-largest-and-smallest-value-in-three-moves "三次操作后最大值与最小值的最小差") | [Go](../problems/minimum-difference-between-largest-and-smallest-value-in-three-moves) | Medium |
-| <span id="1510">1510</span> | [Stone Game IV](https://leetcode.com/problems/stone-game-iv "石子游戏 IV") | [Go](../problems/stone-game-iv) | Hard |
-| <span id="1511">1511</span> | [Customer Order Frequency](https://leetcode.com/problems/customer-order-frequency "消费者下单频率") 🔒 | [MySQL](../problems/customer-order-frequency) | Easy |
-| <span id="1512">1512</span> | [Number of Good Pairs](https://leetcode.com/problems/number-of-good-pairs "好数对的数目") | [Go](../problems/number-of-good-pairs) | Easy |
-| <span id="1513">1513</span> | [Number of Substrings With Only 1s](https://leetcode.com/problems/number-of-substrings-with-only-1s "仅含 1 的子串数") | [Go](../problems/number-of-substrings-with-only-1s) | Medium |
-| <span id="1514">1514</span> | [Path with Maximum Probability](https://leetcode.com/problems/path-with-maximum-probability "概率最大的路径") | [Go](../problems/path-with-maximum-probability) | Medium |
-| <span id="1515">1515</span> | [Best Position for a Service Centre](https://leetcode.com/problems/best-position-for-a-service-centre "服务中心的最佳位置") | [Go](../problems/best-position-for-a-service-centre) | Hard |
-| <span id="1516">1516</span> | [Move Sub-Tree of N-Ary Tree](https://leetcode.com/problems/move-sub-tree-of-n-ary-tree "移动 N 叉树的子树") 🔒 | [Go](../problems/move-sub-tree-of-n-ary-tree) | Hard |
-| <span id="1517">1517</span> | [Find Users With Valid E-Mails](https://leetcode.com/problems/find-users-with-valid-e-mails "查找拥有有效邮箱的用户") 🔒 | [MySQL](../problems/find-users-with-valid-e-mails) | Easy |
-| <span id="1518">1518</span> | [Water Bottles](https://leetcode.com/problems/water-bottles "换酒问题") | [Go](../problems/water-bottles) | Easy |
-| <span id="1519">1519</span> | [Number of Nodes in the Sub-Tree With the Same Label](https://leetcode.com/problems/number-of-nodes-in-the-sub-tree-with-the-same-label "子树中标签相同的节点数") | [Go](../problems/number-of-nodes-in-the-sub-tree-with-the-same-label) | Medium |
-| <span id="1520">1520</span> | [Maximum Number of Non-Overlapping Substrings](https://leetcode.com/problems/maximum-number-of-non-overlapping-substrings "最多的不重叠子字符串") | [Go](../problems/maximum-number-of-non-overlapping-substrings) | Hard |
-| <span id="1521">1521</span> | [Find a Value of a Mysterious Function Closest to Target](https://leetcode.com/problems/find-a-value-of-a-mysterious-function-closest-to-target "找到最接近目标值的函数值") | [Go](../problems/find-a-value-of-a-mysterious-function-closest-to-target) | Hard |
-| <span id="1522">1522</span> | [Diameter of N-Ary Tree](https://leetcode.com/problems/diameter-of-n-ary-tree "N 叉树的直径") 🔒 | [Go](../problems/diameter-of-n-ary-tree) | Medium |
-| <span id="1523">1523</span> | [Count Odd Numbers in an Interval Range](https://leetcode.com/problems/count-odd-numbers-in-an-interval-range "在区间范围内统计奇数数目") | [Go](../problems/count-odd-numbers-in-an-interval-range) | Easy |
-| <span id="1524">1524</span> | [Number of Sub-arrays With Odd Sum](https://leetcode.com/problems/number-of-sub-arrays-with-odd-sum "和为奇数的子数组数目") | [Go](../problems/number-of-sub-arrays-with-odd-sum) | Medium |
-| <span id="1525">1525</span> | [Number of Good Ways to Split a String](https://leetcode.com/problems/number-of-good-ways-to-split-a-string "字符串的好分割数目") | [Go](../problems/number-of-good-ways-to-split-a-string) | Medium |
-| <span id="1526">1526</span> | [Minimum Number of Increments on Subarrays to Form a Target Array](https://leetcode.com/problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array "形成目标数组的子数组最少增加次数") | [Go](../problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array) | Hard |
-| <span id="1527">1527</span> | [Patients With a Condition](https://leetcode.com/problems/patients-with-a-condition "患某种疾病的患者") 🔒 | [MySQL](../problems/patients-with-a-condition) | Easy |
-| <span id="1528">1528</span> | [Shuffle String](https://leetcode.com/problems/shuffle-string "重新排列字符串") | [Go](../problems/shuffle-string) | Easy |
-| <span id="1529">1529</span> | [Minimum Suffix Flips](https://leetcode.com/problems/minimum-suffix-flips "最少的后缀翻转次数") | [Go](../problems/minimum-suffix-flips) | Medium |
-| <span id="1530">1530</span> | [Number of Good Leaf Nodes Pairs](https://leetcode.com/problems/number-of-good-leaf-nodes-pairs "好叶子节点对的数量") | [Go](../problems/number-of-good-leaf-nodes-pairs) | Medium |
-| <span id="1531">1531</span> | [String Compression II](https://leetcode.com/problems/string-compression-ii "压缩字符串 II") | [Go](../problems/string-compression-ii) | Hard |
-| <span id="1532">1532</span> | [The Most Recent Three Orders](https://leetcode.com/problems/the-most-recent-three-orders "最近的三笔订单") 🔒 | [MySQL](../problems/the-most-recent-three-orders) | Medium |
-| <span id="1533">1533</span> | [Find the Index of the Large Integer](https://leetcode.com/problems/find-the-index-of-the-large-integer "找到最大整数的索引") 🔒 | [Go](../problems/find-the-index-of-the-large-integer) | Medium |
-| <span id="1534">1534</span> | [Count Good Triplets](https://leetcode.com/problems/count-good-triplets "统计好三元组") | [Go](../problems/count-good-triplets) | Easy |
-| <span id="1535">1535</span> | [Find the Winner of an Array Game](https://leetcode.com/problems/find-the-winner-of-an-array-game "找出数组游戏的赢家") | [Go](../problems/find-the-winner-of-an-array-game) | Medium |
-| <span id="1536">1536</span> | [Minimum Swaps to Arrange a Binary Grid](https://leetcode.com/problems/minimum-swaps-to-arrange-a-binary-grid "排布二进制网格的最少交换次数") | [Go](../problems/minimum-swaps-to-arrange-a-binary-grid) | Medium |
-| <span id="1537">1537</span> | [Get the Maximum Score](https://leetcode.com/problems/get-the-maximum-score "最大得分") | [Go](../problems/get-the-maximum-score) | Hard |
-| <span id="1538">1538</span> | [Guess the Majority in a Hidden Array](https://leetcode.com/problems/guess-the-majority-in-a-hidden-array "找出隐藏数组中出现次数最多的元素") 🔒 | [Go](../problems/guess-the-majority-in-a-hidden-array) | Medium |
-| <span id="1539">1539</span> | [Kth Missing Positive Number](https://leetcode.com/problems/kth-missing-positive-number "第 k 个缺失的正整数") | [Go](../problems/kth-missing-positive-number) | Easy |
-| <span id="1540">1540</span> | [Can Convert String in K Moves](https://leetcode.com/problems/can-convert-string-in-k-moves "K 次操作转变字符串") | [Go](../problems/can-convert-string-in-k-moves) | Medium |
-| <span id="1541">1541</span> | [Minimum Insertions to Balance a Parentheses String](https://leetcode.com/problems/minimum-insertions-to-balance-a-parentheses-string "平衡括号字符串的最少插入次数") | [Go](../problems/minimum-insertions-to-balance-a-parentheses-string) | Medium |
-| <span id="1542">1542</span> | [Find Longest Awesome Substring](https://leetcode.com/problems/find-longest-awesome-substring "找出最长的超赞子字符串") | [Go](../problems/find-longest-awesome-substring) | Hard |
-| <span id="1543">1543</span> | [Fix Product Name Format](https://leetcode.com/problems/fix-product-name-format "产品名称格式修复") 🔒 | [MySQL](../problems/fix-product-name-format) | Easy |
-| <span id="1544">1544</span> | [Make The String Great](https://leetcode.com/problems/make-the-string-great "整理字符串") | [Go](../problems/make-the-string-great) | Easy |
-| <span id="1545">1545</span> | [Find Kth Bit in Nth Binary String](https://leetcode.com/problems/find-kth-bit-in-nth-binary-string "找出第 N 个二进制字符串中的第 K 位") | [Go](../problems/find-kth-bit-in-nth-binary-string) | Medium |
-| <span id="1546">1546</span> | [Maximum Number of Non-Overlapping Subarrays With Sum Equals Target](https://leetcode.com/problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target "和为目标值且不重叠的非空子数组的最大数目") | [Go](../problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target) | Medium |
-| <span id="1547">1547</span> | [Minimum Cost to Cut a Stick](https://leetcode.com/problems/minimum-cost-to-cut-a-stick "切棍子的最小成本") | [Go](../problems/minimum-cost-to-cut-a-stick) | Hard |
-| <span id="1548">1548</span> | [The Most Similar Path in a Graph](https://leetcode.com/problems/the-most-similar-path-in-a-graph "图中最相似的路径") 🔒 | [Go](../problems/the-most-similar-path-in-a-graph) | Hard |
-| <span id="1549">1549</span> | [The Most Recent Orders for Each Product](https://leetcode.com/problems/the-most-recent-orders-for-each-product "每件商品的最新订单") 🔒 | [MySQL](../problems/the-most-recent-orders-for-each-product) | Medium |
-| <span id="1550">1550</span> | [Three Consecutive Odds](https://leetcode.com/problems/three-consecutive-odds "存在连续三个奇数的数组") | [Go](../problems/three-consecutive-odds) | Easy |
-| <span id="1551">1551</span> | [Minimum Operations to Make Array Equal](https://leetcode.com/problems/minimum-operations-to-make-array-equal "使数组中所有元素相等的最小操作数") | [Go](../problems/minimum-operations-to-make-array-equal) | Medium |
-| <span id="1552">1552</span> | [Magnetic Force Between Two Balls](https://leetcode.com/problems/magnetic-force-between-two-balls "两球之间的磁力") | [Go](../problems/magnetic-force-between-two-balls) | Medium |
-| <span id="1553">1553</span> | [Minimum Number of Days to Eat N Oranges](https://leetcode.com/problems/minimum-number-of-days-to-eat-n-oranges "吃掉 N 个橘子的最少天数") | [Go](../problems/minimum-number-of-days-to-eat-n-oranges) | Hard |
-| <span id="1554">1554</span> | [Strings Differ by One Character](https://leetcode.com/problems/strings-differ-by-one-character "只有一个不同字符的字符串") 🔒 | [Go](../problems/strings-differ-by-one-character) | Medium |
-| <span id="1555">1555</span> | [Bank Account Summary](https://leetcode.com/problems/bank-account-summary "银行账户概要") 🔒 | [MySQL](../problems/bank-account-summary) | Medium |
-| <span id="1556">1556</span> | [Thousand Separator](https://leetcode.com/problems/thousand-separator "千位分隔数") | [Go](../problems/thousand-separator) | Easy |
-| <span id="1557">1557</span> | [Minimum Number of Vertices to Reach All Nodes](https://leetcode.com/problems/minimum-number-of-vertices-to-reach-all-nodes "可以到达所有点的最少点数目") | [Go](../problems/minimum-number-of-vertices-to-reach-all-nodes) | Medium |
-| <span id="1558">1558</span> | [Minimum Numbers of Function Calls to Make Target Array](https://leetcode.com/problems/minimum-numbers-of-function-calls-to-make-target-array "得到目标数组的最少函数调用次数") | [Go](../problems/minimum-numbers-of-function-calls-to-make-target-array) | Medium |
-| <span id="1559">1559</span> | [Detect Cycles in 2D Grid](https://leetcode.com/problems/detect-cycles-in-2d-grid "二维网格图中探测环") | [Go](../problems/detect-cycles-in-2d-grid) | Medium |
-| <span id="1560">1560</span> | [Most Visited Sector in  a Circular Track](https://leetcode.com/problems/most-visited-sector-in-a-circular-track "圆形赛道上经过次数最多的扇区") | [Go](../problems/most-visited-sector-in-a-circular-track) | Easy |
-| <span id="1561">1561</span> | [Maximum Number of Coins You Can Get](https://leetcode.com/problems/maximum-number-of-coins-you-can-get "你可以获得的最大硬币数目") | [Go](../problems/maximum-number-of-coins-you-can-get) | Medium |
-| <span id="1562">1562</span> | [Find Latest Group of Size M](https://leetcode.com/problems/find-latest-group-of-size-m "查找大小为 M 的最新分组") | [Go](../problems/find-latest-group-of-size-m) | Medium |
-| <span id="1563">1563</span> | [Stone Game V](https://leetcode.com/problems/stone-game-v "石子游戏 V") | [Go](../problems/stone-game-v) | Hard |
-| <span id="1564">1564</span> | [Put Boxes Into the Warehouse I](https://leetcode.com/problems/put-boxes-into-the-warehouse-i "把箱子放进仓库里 I") 🔒 | [Go](../problems/put-boxes-into-the-warehouse-i) | Medium |
-| <span id="1565">1565</span> | [Unique Orders and Customers Per Month](https://leetcode.com/problems/unique-orders-and-customers-per-month "按月统计订单数与顾客数") 🔒 | [MySQL](../problems/unique-orders-and-customers-per-month) | Easy |
-| <span id="1566">1566</span> | [Detect Pattern of Length M Repeated K or More Times](https://leetcode.com/problems/detect-pattern-of-length-m-repeated-k-or-more-times "重复至少 K 次且长度为 M 的模式") | [Go](../problems/detect-pattern-of-length-m-repeated-k-or-more-times) | Easy |
-| <span id="1567">1567</span> | [Maximum Length of Subarray With Positive Product](https://leetcode.com/problems/maximum-length-of-subarray-with-positive-product "乘积为正数的最长子数组长度") | [Go](../problems/maximum-length-of-subarray-with-positive-product) | Medium |
-| <span id="1568">1568</span> | [Minimum Number of Days to Disconnect Island](https://leetcode.com/problems/minimum-number-of-days-to-disconnect-island "使陆地分离的最少天数") | [Go](../problems/minimum-number-of-days-to-disconnect-island) | Hard |
-| <span id="1569">1569</span> | [Number of Ways to Reorder Array to Get Same BST](https://leetcode.com/problems/number-of-ways-to-reorder-array-to-get-same-bst "将子数组重新排序得到同一个二叉查找树的方案数") | [Go](../problems/number-of-ways-to-reorder-array-to-get-same-bst) | Hard |
-| <span id="1570">1570</span> | [Dot Product of Two Sparse Vectors](https://leetcode.com/problems/dot-product-of-two-sparse-vectors "两个稀疏向量的点积") 🔒 | [Go](../problems/dot-product-of-two-sparse-vectors) | Medium |
-| <span id="1571">1571</span> | [Warehouse Manager](https://leetcode.com/problems/warehouse-manager "仓库经理") 🔒 | [MySQL](../problems/warehouse-manager) | Easy |
-| <span id="1572">1572</span> | [Matrix Diagonal Sum](https://leetcode.com/problems/matrix-diagonal-sum "矩阵对角线元素的和") | [Go](../problems/matrix-diagonal-sum) | Easy |
-| <span id="1573">1573</span> | [Number of Ways to Split a String](https://leetcode.com/problems/number-of-ways-to-split-a-string "分割字符串的方案数") | [Go](../problems/number-of-ways-to-split-a-string) | Medium |
-| <span id="1574">1574</span> | [Shortest Subarray to be Removed to Make Array Sorted](https://leetcode.com/problems/shortest-subarray-to-be-removed-to-make-array-sorted "删除最短的子数组使剩余数组有序") | [Go](../problems/shortest-subarray-to-be-removed-to-make-array-sorted) | Medium |
-| <span id="1575">1575</span> | [Count All Possible Routes](https://leetcode.com/problems/count-all-possible-routes "统计所有可行路径") | [Go](../problems/count-all-possible-routes) | Hard |
-| <span id="1576">1576</span> | [Replace All ?'s to Avoid Consecutive Repeating Characters](https://leetcode.com/problems/replace-all-s-to-avoid-consecutive-repeating-characters "替换所有的问号") | [Go](../problems/replace-all-s-to-avoid-consecutive-repeating-characters) | Easy |
-| <span id="1577">1577</span> | [Number of Ways Where Square of Number Is Equal to Product of Two Numbers](https://leetcode.com/problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers "数的平方等于两数乘积的方法数") | [Go](../problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers) | Medium |
-| <span id="1578">1578</span> | [Minimum Time to Make Rope Colorful](https://leetcode.com/problems/minimum-time-to-make-rope-colorful "使绳子变成彩色的最短时间") | [Go](../problems/minimum-time-to-make-rope-colorful) | Medium |
-| <span id="1579">1579</span> | [Remove Max Number of Edges to Keep Graph Fully Traversable](https://leetcode.com/problems/remove-max-number-of-edges-to-keep-graph-fully-traversable "保证图可完全遍历") | [Go](../problems/remove-max-number-of-edges-to-keep-graph-fully-traversable) | Hard |
-| <span id="1580">1580</span> | [Put Boxes Into the Warehouse II](https://leetcode.com/problems/put-boxes-into-the-warehouse-ii "把箱子放进仓库里 II") 🔒 | [Go](../problems/put-boxes-into-the-warehouse-ii) | Medium |
-| <span id="1581">1581</span> | [Customer Who Visited but Did Not Make Any Transactions](https://leetcode.com/problems/customer-who-visited-but-did-not-make-any-transactions "进店却未进行过交易的顾客") 🔒 | [MySQL](../problems/customer-who-visited-but-did-not-make-any-transactions) | Easy |
-| <span id="1582">1582</span> | [Special Positions in a Binary Matrix](https://leetcode.com/problems/special-positions-in-a-binary-matrix "二进制矩阵中的特殊位置") | [Go](../problems/special-positions-in-a-binary-matrix) | Easy |
-| <span id="1583">1583</span> | [Count Unhappy Friends](https://leetcode.com/problems/count-unhappy-friends "统计不开心的朋友") | [Go](../problems/count-unhappy-friends) | Medium |
-| <span id="1584">1584</span> | [Min Cost to Connect All Points](https://leetcode.com/problems/min-cost-to-connect-all-points "连接所有点的最小费用") | [Go](../problems/min-cost-to-connect-all-points) | Medium |
-| <span id="1585">1585</span> | [Check If String Is Transformable With Substring Sort Operations](https://leetcode.com/problems/check-if-string-is-transformable-with-substring-sort-operations "检查字符串是否可以通过排序子字符串得到另一个字符串") | [Go](../problems/check-if-string-is-transformable-with-substring-sort-operations) | Hard |
-| <span id="1586">1586</span> | [Binary Search Tree Iterator II](https://leetcode.com/problems/binary-search-tree-iterator-ii "二叉搜索树迭代器 II") 🔒 | [Go](../problems/binary-search-tree-iterator-ii) | Medium |
-| <span id="1587">1587</span> | [Bank Account Summary II](https://leetcode.com/problems/bank-account-summary-ii "银行账户概要 II") 🔒 | [MySQL](../problems/bank-account-summary-ii) | Easy |
-| <span id="1588">1588</span> | [Sum of All Odd Length Subarrays](https://leetcode.com/problems/sum-of-all-odd-length-subarrays "所有奇数长度子数组的和") | [Go](../problems/sum-of-all-odd-length-subarrays) | Easy |
-| <span id="1589">1589</span> | [Maximum Sum Obtained of Any Permutation](https://leetcode.com/problems/maximum-sum-obtained-of-any-permutation "所有排列中的最大和") | [Go](../problems/maximum-sum-obtained-of-any-permutation) | Medium |
-| <span id="1590">1590</span> | [Make Sum Divisible by P](https://leetcode.com/problems/make-sum-divisible-by-p "使数组和能被 P 整除") | [Go](../problems/make-sum-divisible-by-p) | Medium |
-| <span id="1591">1591</span> | [Strange Printer II](https://leetcode.com/problems/strange-printer-ii "奇怪的打印机 II") | [Go](../problems/strange-printer-ii) | Hard |
-| <span id="1592">1592</span> | [Rearrange Spaces Between Words](https://leetcode.com/problems/rearrange-spaces-between-words "重新排列单词间的空格") | [Go](../problems/rearrange-spaces-between-words) | Easy |
-| <span id="1593">1593</span> | [Split a String Into the Max Number of Unique Substrings](https://leetcode.com/problems/split-a-string-into-the-max-number-of-unique-substrings "拆分字符串使唯一子字符串的数目最大") | [Go](../problems/split-a-string-into-the-max-number-of-unique-substrings) | Medium |
-| <span id="1594">1594</span> | [Maximum Non Negative Product in a Matrix](https://leetcode.com/problems/maximum-non-negative-product-in-a-matrix "矩阵的最大非负积") | [Go](../problems/maximum-non-negative-product-in-a-matrix) | Medium |
-| <span id="1595">1595</span> | [Minimum Cost to Connect Two Groups of Points](https://leetcode.com/problems/minimum-cost-to-connect-two-groups-of-points "连通两组点的最小成本") | [Go](../problems/minimum-cost-to-connect-two-groups-of-points) | Hard |
-| <span id="1596">1596</span> | [The Most Frequently Ordered Products for Each Customer](https://leetcode.com/problems/the-most-frequently-ordered-products-for-each-customer "每位顾客最经常订购的商品") 🔒 | [MySQL](../problems/the-most-frequently-ordered-products-for-each-customer) | Medium |
-| <span id="1597">1597</span> | [Build Binary Expression Tree From Infix Expression](https://leetcode.com/problems/build-binary-expression-tree-from-infix-expression "根据中缀表达式构造二叉表达式树") 🔒 | [Go](../problems/build-binary-expression-tree-from-infix-expression) | Hard |
-| <span id="1598">1598</span> | [Crawler Log Folder](https://leetcode.com/problems/crawler-log-folder "文件夹操作日志搜集器") | [Go](../problems/crawler-log-folder) | Easy |
-| <span id="1599">1599</span> | [Maximum Profit of Operating a Centennial Wheel](https://leetcode.com/problems/maximum-profit-of-operating-a-centennial-wheel "经营摩天轮的最大利润") | [Go](../problems/maximum-profit-of-operating-a-centennial-wheel) | Medium |
-| <span id="1600">1600</span> | [Throne Inheritance](https://leetcode.com/problems/throne-inheritance "皇位继承顺序") | [Go](../problems/throne-inheritance) | Medium |
-| <span id="1601">1601</span> | [Maximum Number of Achievable Transfer Requests](https://leetcode.com/problems/maximum-number-of-achievable-transfer-requests "最多可达成的换楼请求数目") | [Go](../problems/maximum-number-of-achievable-transfer-requests) | Hard |
-| <span id="1602">1602</span> | [Find Nearest Right Node in Binary Tree](https://leetcode.com/problems/find-nearest-right-node-in-binary-tree "找到二叉树中最近的右侧节点") 🔒 | [Go](../problems/find-nearest-right-node-in-binary-tree) | Medium |
-| <span id="1603">1603</span> | [Design Parking System](https://leetcode.com/problems/design-parking-system "设计停车系统") | [Go](../problems/design-parking-system) | Easy |
-| <span id="1604">1604</span> | [Alert Using Same Key-Card Three or More Times in a One Hour Period](https://leetcode.com/problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period "警告一小时内使用相同员工卡大于等于三次的人") | [Go](../problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period) | Medium |
-| <span id="1605">1605</span> | [Find Valid Matrix Given Row and Column Sums](https://leetcode.com/problems/find-valid-matrix-given-row-and-column-sums "给定行和列的和求可行矩阵") | [Go](../problems/find-valid-matrix-given-row-and-column-sums) | Medium |
-| <span id="1606">1606</span> | [Find Servers That Handled Most Number of Requests](https://leetcode.com/problems/find-servers-that-handled-most-number-of-requests "找到处理最多请求的服务器") | [Go](../problems/find-servers-that-handled-most-number-of-requests) | Hard |
-| <span id="1607">1607</span> | [Sellers With No Sales](https://leetcode.com/problems/sellers-with-no-sales "没有卖出的卖家") 🔒 | [MySQL](../problems/sellers-with-no-sales) | Easy |
-| <span id="1608">1608</span> | [Special Array With X Elements Greater Than or Equal X](https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x "特殊数组的特征值") | [Go](../problems/special-array-with-x-elements-greater-than-or-equal-x) | Easy |
-| <span id="1609">1609</span> | [Even Odd Tree](https://leetcode.com/problems/even-odd-tree "奇偶树") | [Go](../problems/even-odd-tree) | Medium |
-| <span id="1610">1610</span> | [Maximum Number of Visible Points](https://leetcode.com/problems/maximum-number-of-visible-points "可见点的最大数目") | [Go](../problems/maximum-number-of-visible-points) | Hard |
-| <span id="1611">1611</span> | [Minimum One Bit Operations to Make Integers Zero](https://leetcode.com/problems/minimum-one-bit-operations-to-make-integers-zero "使整数变为 0 的最少操作次数") | [Go](../problems/minimum-one-bit-operations-to-make-integers-zero) | Hard |
-| <span id="1612">1612</span> | [Check If Two Expression Trees are Equivalent](https://leetcode.com/problems/check-if-two-expression-trees-are-equivalent "检查两棵二叉表达式树是否等价") 🔒 | [Go](../problems/check-if-two-expression-trees-are-equivalent) | Medium |
-| <span id="1613">1613</span> | [Find the Missing IDs](https://leetcode.com/problems/find-the-missing-ids "找到遗失的ID") 🔒 | [MySQL](../problems/find-the-missing-ids) | Medium |
-| <span id="1614">1614</span> | [Maximum Nesting Depth of the Parentheses](https://leetcode.com/problems/maximum-nesting-depth-of-the-parentheses "括号的最大嵌套深度") | [Go](../problems/maximum-nesting-depth-of-the-parentheses) | Easy |
-| <span id="1615">1615</span> | [Maximal Network Rank](https://leetcode.com/problems/maximal-network-rank "最大网络秩") | [Go](../problems/maximal-network-rank) | Medium |
-| <span id="1616">1616</span> | [Split Two Strings to Make Palindrome](https://leetcode.com/problems/split-two-strings-to-make-palindrome "分割两个字符串得到回文串") | [Go](../problems/split-two-strings-to-make-palindrome) | Medium |
-| <span id="1617">1617</span> | [Count Subtrees With Max Distance Between Cities](https://leetcode.com/problems/count-subtrees-with-max-distance-between-cities "统计子树中城市之间最大距离") | [Go](../problems/count-subtrees-with-max-distance-between-cities) | Hard |
-| <span id="1618">1618</span> | [Maximum Font to Fit a Sentence in a Screen](https://leetcode.com/problems/maximum-font-to-fit-a-sentence-in-a-screen "找出适应屏幕的最大字号") 🔒 | [Go](../problems/maximum-font-to-fit-a-sentence-in-a-screen) | Medium |
-| <span id="1619">1619</span> | [Mean of Array After Removing Some Elements](https://leetcode.com/problems/mean-of-array-after-removing-some-elements "删除某些元素后的数组均值") | [Go](../problems/mean-of-array-after-removing-some-elements) | Easy |
-| <span id="1620">1620</span> | [Coordinate With Maximum Network Quality](https://leetcode.com/problems/coordinate-with-maximum-network-quality "网络信号最好的坐标") | [Go](../problems/coordinate-with-maximum-network-quality) | Medium |
-| <span id="1621">1621</span> | [Number of Sets of K Non-Overlapping Line Segments](https://leetcode.com/problems/number-of-sets-of-k-non-overlapping-line-segments "大小为 K 的不重叠线段的数目") | [Go](../problems/number-of-sets-of-k-non-overlapping-line-segments) | Medium |
-| <span id="1622">1622</span> | [Fancy Sequence](https://leetcode.com/problems/fancy-sequence "奇妙序列") | [Go](../problems/fancy-sequence) | Hard |
-| <span id="1623">1623</span> | [All Valid Triplets That Can Represent a Country](https://leetcode.com/problems/all-valid-triplets-that-can-represent-a-country "三人国家代表队") 🔒 | [MySQL](../problems/all-valid-triplets-that-can-represent-a-country) | Easy |
-| <span id="1624">1624</span> | [Largest Substring Between Two Equal Characters](https://leetcode.com/problems/largest-substring-between-two-equal-characters "两个相同字符之间的最长子字符串") | [Go](../problems/largest-substring-between-two-equal-characters) | Easy |
-| <span id="1625">1625</span> | [Lexicographically Smallest String After Applying Operations](https://leetcode.com/problems/lexicographically-smallest-string-after-applying-operations "执行操作后字典序最小的字符串") | [Go](../problems/lexicographically-smallest-string-after-applying-operations) | Medium |
-| <span id="1626">1626</span> | [Best Team With No Conflicts](https://leetcode.com/problems/best-team-with-no-conflicts "无矛盾的最佳球队") | [Go](../problems/best-team-with-no-conflicts) | Medium |
-| <span id="1627">1627</span> | [Graph Connectivity With Threshold](https://leetcode.com/problems/graph-connectivity-with-threshold "带阈值的图连通性") | [Go](../problems/graph-connectivity-with-threshold) | Hard |
-| <span id="1628">1628</span> | [Design an Expression Tree With Evaluate Function](https://leetcode.com/problems/design-an-expression-tree-with-evaluate-function "设计带解析函数的表达式树") 🔒 | [Go](../problems/design-an-expression-tree-with-evaluate-function) | Medium |
-| <span id="1629">1629</span> | [Slowest Key](https://leetcode.com/problems/slowest-key "按键持续时间最长的键") | [Go](../problems/slowest-key) | Easy |
-| <span id="1630">1630</span> | [Arithmetic Subarrays](https://leetcode.com/problems/arithmetic-subarrays "等差子数组") | [Go](../problems/arithmetic-subarrays) | Medium |
-| <span id="1631">1631</span> | [Path With Minimum Effort](https://leetcode.com/problems/path-with-minimum-effort "最小体力消耗路径") | [Go](../problems/path-with-minimum-effort) | Medium |
-| <span id="1632">1632</span> | [Rank Transform of a Matrix](https://leetcode.com/problems/rank-transform-of-a-matrix "矩阵转换后的秩") | [Go](../problems/rank-transform-of-a-matrix) | Hard |
-| <span id="1633">1633</span> | [Percentage of Users Attended a Contest](https://leetcode.com/problems/percentage-of-users-attended-a-contest "各赛事的用户注册率") 🔒 | [MySQL](../problems/percentage-of-users-attended-a-contest) | Easy |
-| <span id="1634">1634</span> | [Add Two Polynomials Represented as Linked Lists](https://leetcode.com/problems/add-two-polynomials-represented-as-linked-lists "求两个多项式链表的和") 🔒 | [Go](../problems/add-two-polynomials-represented-as-linked-lists) | Medium |
-| <span id="1635">1635</span> | [Hopper Company Queries I](https://leetcode.com/problems/hopper-company-queries-i "Hopper 公司查询 I") 🔒 | [MySQL](../problems/hopper-company-queries-i) | Hard |
-| <span id="1636">1636</span> | [Sort Array by Increasing Frequency](https://leetcode.com/problems/sort-array-by-increasing-frequency "按照频率将数组升序排序") | [Go](../problems/sort-array-by-increasing-frequency) | Easy |
-| <span id="1637">1637</span> | [Widest Vertical Area Between Two Points Containing No Points](https://leetcode.com/problems/widest-vertical-area-between-two-points-containing-no-points "两点之间不包含任何点的最宽垂直面积") | [Go](../problems/widest-vertical-area-between-two-points-containing-no-points) | Medium |
-| <span id="1638">1638</span> | [Count Substrings That Differ by One Character](https://leetcode.com/problems/count-substrings-that-differ-by-one-character "统计只差一个字符的子串数目") | [Go](../problems/count-substrings-that-differ-by-one-character) | Medium |
-| <span id="1639">1639</span> | [Number of Ways to Form a Target String Given a Dictionary](https://leetcode.com/problems/number-of-ways-to-form-a-target-string-given-a-dictionary "通过给定词典构造目标字符串的方案数") | [Go](../problems/number-of-ways-to-form-a-target-string-given-a-dictionary) | Hard |
-| <span id="1640">1640</span> | [Check Array Formation Through Concatenation](https://leetcode.com/problems/check-array-formation-through-concatenation "能否连接形成数组") | [Go](../problems/check-array-formation-through-concatenation) | Easy |
-| <span id="1641">1641</span> | [Count Sorted Vowel Strings](https://leetcode.com/problems/count-sorted-vowel-strings "统计字典序元音字符串的数目") | [Go](../problems/count-sorted-vowel-strings) | Medium |
-| <span id="1642">1642</span> | [Furthest Building You Can Reach](https://leetcode.com/problems/furthest-building-you-can-reach "可以到达的最远建筑") | [Go](../problems/furthest-building-you-can-reach) | Medium |
-| <span id="1643">1643</span> | [Kth Smallest Instructions](https://leetcode.com/problems/kth-smallest-instructions "第 K 条最小指令") | [Go](../problems/kth-smallest-instructions) | Hard |
-| <span id="1644">1644</span> | [Lowest Common Ancestor of a Binary Tree II](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-ii "二叉树的最近公共祖先 II") 🔒 | [Go](../problems/lowest-common-ancestor-of-a-binary-tree-ii) | Medium |
-| <span id="1645">1645</span> | [Hopper Company Queries II](https://leetcode.com/problems/hopper-company-queries-ii) 🔒 | [MySQL](../problems/hopper-company-queries-ii) | Hard |
-| <span id="1646">1646</span> | [Get Maximum in Generated Array](https://leetcode.com/problems/get-maximum-in-generated-array "获取生成数组中的最大值") | [Go](../problems/get-maximum-in-generated-array) | Easy |
-| <span id="1647">1647</span> | [Minimum Deletions to Make Character Frequencies Unique](https://leetcode.com/problems/minimum-deletions-to-make-character-frequencies-unique "字符频次唯一的最小删除次数") | [Go](../problems/minimum-deletions-to-make-character-frequencies-unique) | Medium |
-| <span id="1648">1648</span> | [Sell Diminishing-Valued Colored Balls](https://leetcode.com/problems/sell-diminishing-valued-colored-balls "销售价值减少的颜色球") | [Go](../problems/sell-diminishing-valued-colored-balls) | Medium |
-| <span id="1649">1649</span> | [Create Sorted Array through Instructions](https://leetcode.com/problems/create-sorted-array-through-instructions "通过指令创建有序数组") | [Go](../problems/create-sorted-array-through-instructions) | Hard |
-| <span id="1650">1650</span> | [Lowest Common Ancestor of a Binary Tree III](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-iii "二叉树的最近公共祖先 III") 🔒 | [Go](../problems/lowest-common-ancestor-of-a-binary-tree-iii) | Medium |
-| <span id="1651">1651</span> | [Hopper Company Queries III](https://leetcode.com/problems/hopper-company-queries-iii) 🔒 | [MySQL](../problems/hopper-company-queries-iii) | Hard |
-| <span id="1652">1652</span> | [Defuse the Bomb](https://leetcode.com/problems/defuse-the-bomb "拆炸弹") | [Go](../problems/defuse-the-bomb) | Easy |
-| <span id="1653">1653</span> | [Minimum Deletions to Make String Balanced](https://leetcode.com/problems/minimum-deletions-to-make-string-balanced "使字符串平衡的最少删除次数") | [Go](../problems/minimum-deletions-to-make-string-balanced) | Medium |
-| <span id="1654">1654</span> | [Minimum Jumps to Reach Home](https://leetcode.com/problems/minimum-jumps-to-reach-home "到家的最少跳跃次数") | [Go](../problems/minimum-jumps-to-reach-home) | Medium |
-| <span id="1655">1655</span> | [Distribute Repeating Integers](https://leetcode.com/problems/distribute-repeating-integers "分配重复整数") | [Go](../problems/distribute-repeating-integers) | Hard |
-| <span id="1656">1656</span> | [Design an Ordered Stream](https://leetcode.com/problems/design-an-ordered-stream "设计有序流") | [Go](../problems/design-an-ordered-stream) | Easy |
-| <span id="1657">1657</span> | [Determine if Two Strings Are Close](https://leetcode.com/problems/determine-if-two-strings-are-close "确定两个字符串是否接近") | [Go](../problems/determine-if-two-strings-are-close) | Medium |
-| <span id="1658">1658</span> | [Minimum Operations to Reduce X to Zero](https://leetcode.com/problems/minimum-operations-to-reduce-x-to-zero "将 x 减到 0 的最小操作数") | [Go](../problems/minimum-operations-to-reduce-x-to-zero) | Medium |
-| <span id="1659">1659</span> | [Maximize Grid Happiness](https://leetcode.com/problems/maximize-grid-happiness "最大化网格幸福感") | [Go](../problems/maximize-grid-happiness) | Hard |
-| <span id="1660">1660</span> | [Correct a Binary Tree](https://leetcode.com/problems/correct-a-binary-tree "纠正二叉树") 🔒 | [Go](../problems/correct-a-binary-tree) | Medium |
-| <span id="1661">1661</span> | [Average Time of Process per Machine](https://leetcode.com/problems/average-time-of-process-per-machine "每台机器的进程平均运行时间") 🔒 | [MySQL](../problems/average-time-of-process-per-machine) | Easy |
-| <span id="1662">1662</span> | [Check If Two String Arrays are Equivalent](https://leetcode.com/problems/check-if-two-string-arrays-are-equivalent "检查两个字符串数组是否相等") | [Go](../problems/check-if-two-string-arrays-are-equivalent) | Easy |
-| <span id="1663">1663</span> | [Smallest String With A Given Numeric Value](https://leetcode.com/problems/smallest-string-with-a-given-numeric-value "具有给定数值的最小字符串") | [Go](../problems/smallest-string-with-a-given-numeric-value) | Medium |
-| <span id="1664">1664</span> | [Ways to Make a Fair Array](https://leetcode.com/problems/ways-to-make-a-fair-array "生成平衡数组的方案数") | [Go](../problems/ways-to-make-a-fair-array) | Medium |
-| <span id="1665">1665</span> | [Minimum Initial Energy to Finish Tasks](https://leetcode.com/problems/minimum-initial-energy-to-finish-tasks "完成所有任务的最少初始能量") | [Go](../problems/minimum-initial-energy-to-finish-tasks) | Hard |
-| <span id="1666">1666</span> | [Change the Root of a Binary Tree](https://leetcode.com/problems/change-the-root-of-a-binary-tree "改变二叉树的根节点") 🔒 | [Go](../problems/change-the-root-of-a-binary-tree) | Medium |
-| <span id="1667">1667</span> | [Fix Names in a Table](https://leetcode.com/problems/fix-names-in-a-table "修复表中的名字") 🔒 | [MySQL](../problems/fix-names-in-a-table) | Easy |
-| <span id="1668">1668</span> | [Maximum Repeating Substring](https://leetcode.com/problems/maximum-repeating-substring "最大重复子字符串") | [Go](../problems/maximum-repeating-substring) | Easy |
-| <span id="1669">1669</span> | [Merge In Between Linked Lists](https://leetcode.com/problems/merge-in-between-linked-lists "合并两个链表") | [Go](../problems/merge-in-between-linked-lists) | Medium |
-| <span id="1670">1670</span> | [Design Front Middle Back Queue](https://leetcode.com/problems/design-front-middle-back-queue "设计前中后队列") | [Go](../problems/design-front-middle-back-queue) | Medium |
-| <span id="1671">1671</span> | [Minimum Number of Removals to Make Mountain Array](https://leetcode.com/problems/minimum-number-of-removals-to-make-mountain-array "得到山形数组的最少删除次数") | [Go](../problems/minimum-number-of-removals-to-make-mountain-array) | Hard |
-| <span id="1672">1672</span> | [Richest Customer Wealth](https://leetcode.com/problems/richest-customer-wealth "最富有客户的资产总量") | [Go](../problems/richest-customer-wealth) | Easy |
-| <span id="1673">1673</span> | [Find the Most Competitive Subsequence](https://leetcode.com/problems/find-the-most-competitive-subsequence "找出最具竞争力的子序列") | [Go](../problems/find-the-most-competitive-subsequence) | Medium |
-| <span id="1674">1674</span> | [Minimum Moves to Make Array Complementary](https://leetcode.com/problems/minimum-moves-to-make-array-complementary "使数组互补的最少操作次数") | [Go](../problems/minimum-moves-to-make-array-complementary) | Medium |
-| <span id="1675">1675</span> | [Minimize Deviation in Array](https://leetcode.com/problems/minimize-deviation-in-array "数组的最小偏移量") | [Go](../problems/minimize-deviation-in-array) | Hard |
-| <span id="1676">1676</span> | [Lowest Common Ancestor of a Binary Tree IV](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-iv "二叉树的最近公共祖先 IV") 🔒 | [Go](../problems/lowest-common-ancestor-of-a-binary-tree-iv) | Medium |
-| <span id="1677">1677</span> | [Product's Worth Over Invoices](https://leetcode.com/problems/products-worth-over-invoices "发票中的产品金额") 🔒 | [MySQL](../problems/products-worth-over-invoices) | Easy |
-| <span id="1678">1678</span> | [Goal Parser Interpretation](https://leetcode.com/problems/goal-parser-interpretation "设计 Goal 解析器") | [Go](../problems/goal-parser-interpretation) | Easy |
-| <span id="1679">1679</span> | [Max Number of K-Sum Pairs](https://leetcode.com/problems/max-number-of-k-sum-pairs "K 和数对的最大数目") | [Go](../problems/max-number-of-k-sum-pairs) | Medium |
-| <span id="1680">1680</span> | [Concatenation of Consecutive Binary Numbers](https://leetcode.com/problems/concatenation-of-consecutive-binary-numbers "连接连续二进制数字") | [Go](../problems/concatenation-of-consecutive-binary-numbers) | Medium |
-| <span id="1681">1681</span> | [Minimum Incompatibility](https://leetcode.com/problems/minimum-incompatibility "最小不兼容性") | [Go](../problems/minimum-incompatibility) | Hard |
-| <span id="1682">1682</span> | [Longest Palindromic Subsequence II](https://leetcode.com/problems/longest-palindromic-subsequence-ii "最长回文子序列 II") 🔒 | [Go](../problems/longest-palindromic-subsequence-ii) | Medium |
-| <span id="1683">1683</span> | [Invalid Tweets](https://leetcode.com/problems/invalid-tweets "无效的推文") 🔒 | [MySQL](../problems/invalid-tweets) | Easy |
-| <span id="1684">1684</span> | [Count the Number of Consistent Strings](https://leetcode.com/problems/count-the-number-of-consistent-strings "统计一致字符串的数目") | [Go](../problems/count-the-number-of-consistent-strings) | Easy |
-| <span id="1685">1685</span> | [Sum of Absolute Differences in a Sorted Array](https://leetcode.com/problems/sum-of-absolute-differences-in-a-sorted-array "有序数组中差绝对值之和") | [Go](../problems/sum-of-absolute-differences-in-a-sorted-array) | Medium |
-| <span id="1686">1686</span> | [Stone Game VI](https://leetcode.com/problems/stone-game-vi "石子游戏 VI") | [Go](../problems/stone-game-vi) | Medium |
-| <span id="1687">1687</span> | [Delivering Boxes from Storage to Ports](https://leetcode.com/problems/delivering-boxes-from-storage-to-ports "从仓库到码头运输箱子") | [Go](../problems/delivering-boxes-from-storage-to-ports) | Hard |
-| <span id="1688">1688</span> | [Count of Matches in Tournament](https://leetcode.com/problems/count-of-matches-in-tournament "比赛中的配对次数") | [Go](../problems/count-of-matches-in-tournament) | Easy |
-| <span id="1689">1689</span> | [Partitioning Into Minimum Number Of Deci-Binary Numbers](https://leetcode.com/problems/partitioning-into-minimum-number-of-deci-binary-numbers "十-二进制数的最少数目") | [Go](../problems/partitioning-into-minimum-number-of-deci-binary-numbers) | Medium |
-| <span id="1690">1690</span> | [Stone Game VII](https://leetcode.com/problems/stone-game-vii "石子游戏 VII") | [Go](../problems/stone-game-vii) | Medium |
-| <span id="1691">1691</span> | [Maximum Height by Stacking Cuboids](https://leetcode.com/problems/maximum-height-by-stacking-cuboids "堆叠长方体的最大高度") | [Go](../problems/maximum-height-by-stacking-cuboids) | Hard |
-| <span id="1692">1692</span> | [Count Ways to Distribute Candies](https://leetcode.com/problems/count-ways-to-distribute-candies "计算分配糖果的不同方式") 🔒 | [Go](../problems/count-ways-to-distribute-candies) | Hard |
-| <span id="1693">1693</span> | [Daily Leads and Partners](https://leetcode.com/problems/daily-leads-and-partners "每天的领导和合伙人") 🔒 | [MySQL](../problems/daily-leads-and-partners) | Easy |
-| <span id="1694">1694</span> | [Reformat Phone Number](https://leetcode.com/problems/reformat-phone-number "重新格式化电话号码") | [Go](../problems/reformat-phone-number) | Easy |
-| <span id="1695">1695</span> | [Maximum Erasure Value](https://leetcode.com/problems/maximum-erasure-value "删除子数组的最大得分") | [Go](../problems/maximum-erasure-value) | Medium |
-| <span id="1696">1696</span> | [Jump Game VI](https://leetcode.com/problems/jump-game-vi "跳跃游戏 VI") | [Go](../problems/jump-game-vi) | Medium |
-| <span id="1697">1697</span> | [Checking Existence of Edge Length Limited Paths](https://leetcode.com/problems/checking-existence-of-edge-length-limited-paths "检查边长度限制的路径是否存在") | [Go](../problems/checking-existence-of-edge-length-limited-paths) | Hard |
-| <span id="1698">1698</span> | [Number of Distinct Substrings in a String](https://leetcode.com/problems/number-of-distinct-substrings-in-a-string "字符串的不同子字符串个数") 🔒 | [Go](../problems/number-of-distinct-substrings-in-a-string) | Medium |
-| <span id="1699">1699</span> | [Number of Calls Between Two Persons](https://leetcode.com/problems/number-of-calls-between-two-persons "两人之间的通话次数") 🔒 | [MySQL](../problems/number-of-calls-between-two-persons) | Medium |
-| <span id="1700">1700</span> | [Number of Students Unable to Eat Lunch](https://leetcode.com/problems/number-of-students-unable-to-eat-lunch "无法吃午餐的学生数量") | [Go](../problems/number-of-students-unable-to-eat-lunch) | Easy |
-| <span id="1701">1701</span> | [Average Waiting Time](https://leetcode.com/problems/average-waiting-time "平均等待时间") | [Go](../problems/average-waiting-time) | Medium |
-| <span id="1702">1702</span> | [Maximum Binary String After Change](https://leetcode.com/problems/maximum-binary-string-after-change "修改后的最大二进制字符串") | [Go](../problems/maximum-binary-string-after-change) | Medium |
-| <span id="1703">1703</span> | [Minimum Adjacent Swaps for K Consecutive Ones](https://leetcode.com/problems/minimum-adjacent-swaps-for-k-consecutive-ones "得到连续 K 个 1 的最少相邻交换次数") | [Go](../problems/minimum-adjacent-swaps-for-k-consecutive-ones) | Hard |
-| <span id="1704">1704</span> | [Determine if String Halves Are Alike](https://leetcode.com/problems/determine-if-string-halves-are-alike "判断字符串的两半是否相似") | [Go](../problems/determine-if-string-halves-are-alike) | Easy |
-| <span id="1705">1705</span> | [Maximum Number of Eaten Apples](https://leetcode.com/problems/maximum-number-of-eaten-apples "吃苹果的最大数目") | [Go](../problems/maximum-number-of-eaten-apples) | Medium |
-| <span id="1706">1706</span> | [Where Will the Ball Fall](https://leetcode.com/problems/where-will-the-ball-fall "球会落何处") | [Go](../problems/where-will-the-ball-fall) | Medium |
-| <span id="1707">1707</span> | [Maximum XOR With an Element From Array](https://leetcode.com/problems/maximum-xor-with-an-element-from-array "与数组中元素的最大异或值") | [Go](../problems/maximum-xor-with-an-element-from-array) | Hard |
-| <span id="1708">1708</span> | [Largest Subarray Length K](https://leetcode.com/problems/largest-subarray-length-k "长度为 K 的最大子数组") 🔒 | [Go](../problems/largest-subarray-length-k) | Easy |
-| <span id="1709">1709</span> | [Biggest Window Between Visits](https://leetcode.com/problems/biggest-window-between-visits "访问日期之间最大的空档期") 🔒 | [MySQL](../problems/biggest-window-between-visits) | Medium |
-| <span id="1710">1710</span> | [Maximum Units on a Truck](https://leetcode.com/problems/maximum-units-on-a-truck "卡车上的最大单元数") | [Go](../problems/maximum-units-on-a-truck) | Easy |
-| <span id="1711">1711</span> | [Count Good Meals](https://leetcode.com/problems/count-good-meals "大餐计数") | [Go](../problems/count-good-meals) | Medium |
-| <span id="1712">1712</span> | [Ways to Split Array Into Three Subarrays](https://leetcode.com/problems/ways-to-split-array-into-three-subarrays "将数组分成三个子数组的方案数") | [Go](../problems/ways-to-split-array-into-three-subarrays) | Medium |
-| <span id="1713">1713</span> | [Minimum Operations to Make a Subsequence](https://leetcode.com/problems/minimum-operations-to-make-a-subsequence "得到子序列的最少操作次数") | [Go](../problems/minimum-operations-to-make-a-subsequence) | Hard |
-| <span id="1714">1714</span> | [Sum Of Special Evenly-Spaced Elements In Array](https://leetcode.com/problems/sum-of-special-evenly-spaced-elements-in-array "数组中特殊等间距元素的和") 🔒 | [Go](../problems/sum-of-special-evenly-spaced-elements-in-array) | Hard |
-| <span id="1715">1715</span> | [Count Apples and Oranges](https://leetcode.com/problems/count-apples-and-oranges "苹果和橘子的个数") 🔒 | [MySQL](../problems/count-apples-and-oranges) | Medium |
-| <span id="1716">1716</span> | [Calculate Money in Leetcode Bank](https://leetcode.com/problems/calculate-money-in-leetcode-bank "计算力扣银行的钱") | [Go](../problems/calculate-money-in-leetcode-bank) | Easy |
-| <span id="1717">1717</span> | [Maximum Score From Removing Substrings](https://leetcode.com/problems/maximum-score-from-removing-substrings "删除子字符串的最大得分") | [Go](../problems/maximum-score-from-removing-substrings) | Medium |
-| <span id="1718">1718</span> | [Construct the Lexicographically Largest Valid Sequence](https://leetcode.com/problems/construct-the-lexicographically-largest-valid-sequence "构建字典序最大的可行序列") | [Go](../problems/construct-the-lexicographically-largest-valid-sequence) | Medium |
-| <span id="1719">1719</span> | [Number Of Ways To Reconstruct A Tree](https://leetcode.com/problems/number-of-ways-to-reconstruct-a-tree "重构一棵树的方案数") | [Go](../problems/number-of-ways-to-reconstruct-a-tree) | Hard |
-| <span id="1720">1720</span> | [Decode XORed Array](https://leetcode.com/problems/decode-xored-array "解码异或后的数组") | [Go](../problems/decode-xored-array) | Easy |
-| <span id="1721">1721</span> | [Swapping Nodes in a Linked List](https://leetcode.com/problems/swapping-nodes-in-a-linked-list "交换链表中的节点") | [Go](../problems/swapping-nodes-in-a-linked-list) | Medium |
-| <span id="1722">1722</span> | [Minimize Hamming Distance After Swap Operations](https://leetcode.com/problems/minimize-hamming-distance-after-swap-operations "执行交换操作后的最小汉明距离") | [Go](../problems/minimize-hamming-distance-after-swap-operations) | Medium |
-| <span id="1723">1723</span> | [Find Minimum Time to Finish All Jobs](https://leetcode.com/problems/find-minimum-time-to-finish-all-jobs "完成所有工作的最短时间") | [Go](../problems/find-minimum-time-to-finish-all-jobs) | Hard |
-| <span id="1724">1724</span> | [Checking Existence of Edge Length Limited Paths II](https://leetcode.com/problems/checking-existence-of-edge-length-limited-paths-ii "检查边长度限制的路径是否存在 II") 🔒 | [Go](../problems/checking-existence-of-edge-length-limited-paths-ii) | Hard |
-| <span id="1725">1725</span> | [Number Of Rectangles That Can Form The Largest Square](https://leetcode.com/problems/number-of-rectangles-that-can-form-the-largest-square "可以形成最大正方形的矩形数目") | [Go](../problems/number-of-rectangles-that-can-form-the-largest-square) | Easy |
-| <span id="1726">1726</span> | [Tuple with Same Product](https://leetcode.com/problems/tuple-with-same-product "同积元组") | [Go](../problems/tuple-with-same-product) | Medium |
-| <span id="1727">1727</span> | [Largest Submatrix With Rearrangements](https://leetcode.com/problems/largest-submatrix-with-rearrangements "重新排列后的最大子矩阵") | [Go](../problems/largest-submatrix-with-rearrangements) | Medium |
-| <span id="1728">1728</span> | [Cat and Mouse II](https://leetcode.com/problems/cat-and-mouse-ii "猫和老鼠 II") | [Go](../problems/cat-and-mouse-ii) | Hard |
-| <span id="1729">1729</span> | [Find Followers Count](https://leetcode.com/problems/find-followers-count "求关注者的数量") 🔒 | [MySQL](../problems/find-followers-count) | Easy |
-| <span id="1730">1730</span> | [Shortest Path to Get Food](https://leetcode.com/problems/shortest-path-to-get-food "获取食物的最短路径") 🔒 | [Go](../problems/shortest-path-to-get-food) | Medium |
-| <span id="1731">1731</span> | [The Number of Employees Which Report to Each Employee](https://leetcode.com/problems/the-number-of-employees-which-report-to-each-employee "每位经理的下属员工数量") 🔒 | [MySQL](../problems/the-number-of-employees-which-report-to-each-employee) | Easy |
-| <span id="1732">1732</span> | [Find the Highest Altitude](https://leetcode.com/problems/find-the-highest-altitude "找到最高海拔") | [Go](../problems/find-the-highest-altitude) | Easy |
-| <span id="1733">1733</span> | [Minimum Number of People to Teach](https://leetcode.com/problems/minimum-number-of-people-to-teach "需要教语言的最少人数") | [Go](../problems/minimum-number-of-people-to-teach) | Medium |
-| <span id="1734">1734</span> | [Decode XORed Permutation](https://leetcode.com/problems/decode-xored-permutation "解码异或后的排列") | [Go](../problems/decode-xored-permutation) | Medium |
-| <span id="1735">1735</span> | [Count Ways to Make Array With Product](https://leetcode.com/problems/count-ways-to-make-array-with-product "生成乘积数组的方案数") | [Go](../problems/count-ways-to-make-array-with-product) | Hard |
-| <span id="1736">1736</span> | [Latest Time by Replacing Hidden Digits](https://leetcode.com/problems/latest-time-by-replacing-hidden-digits "替换隐藏数字得到的最晚时间") | [Go](../problems/latest-time-by-replacing-hidden-digits) | Easy |
-| <span id="1737">1737</span> | [Change Minimum Characters to Satisfy One of Three Conditions](https://leetcode.com/problems/change-minimum-characters-to-satisfy-one-of-three-conditions "满足三条件之一需改变的最少字符数") | [Go](../problems/change-minimum-characters-to-satisfy-one-of-three-conditions) | Medium |
-| <span id="1738">1738</span> | [Find Kth Largest XOR Coordinate Value](https://leetcode.com/problems/find-kth-largest-xor-coordinate-value "找出第 K 大的异或坐标值") | [Go](../problems/find-kth-largest-xor-coordinate-value) | Medium |
-| <span id="1739">1739</span> | [Building Boxes](https://leetcode.com/problems/building-boxes "放置盒子") | [Go](../problems/building-boxes) | Hard |
-| <span id="1740">1740</span> | [Find Distance in a Binary Tree](https://leetcode.com/problems/find-distance-in-a-binary-tree "找到二叉树中的距离") 🔒 | [Go](../problems/find-distance-in-a-binary-tree) | Medium |
-| <span id="1741">1741</span> | [Find Total Time Spent by Each Employee](https://leetcode.com/problems/find-total-time-spent-by-each-employee "查找每个员工花费的总时间") 🔒 | [MySQL](../problems/find-total-time-spent-by-each-employee) | Easy |
-| <span id="1742">1742</span> | [Maximum Number of Balls in a Box](https://leetcode.com/problems/maximum-number-of-balls-in-a-box "盒子中小球的最大数量") | [Go](../problems/maximum-number-of-balls-in-a-box) | Easy |
-| <span id="1743">1743</span> | [Restore the Array From Adjacent Pairs](https://leetcode.com/problems/restore-the-array-from-adjacent-pairs "从相邻元素对还原数组") | [Go](../problems/restore-the-array-from-adjacent-pairs) | Medium |
-| <span id="1744">1744</span> | [Can You Eat Your Favorite Candy on Your Favorite Day?](https://leetcode.com/problems/can-you-eat-your-favorite-candy-on-your-favorite-day "你能在你最喜欢的那天吃到你最喜欢的糖果吗？") | [Go](../problems/can-you-eat-your-favorite-candy-on-your-favorite-day) | Medium |
-| <span id="1745">1745</span> | [Palindrome Partitioning IV](https://leetcode.com/problems/palindrome-partitioning-iv "回文串分割 IV") | [Go](../problems/palindrome-partitioning-iv) | Hard |
-| <span id="1746">1746</span> | [Maximum Subarray Sum After One Operation](https://leetcode.com/problems/maximum-subarray-sum-after-one-operation "经过一次操作后的最大子数组和") 🔒 | [Go](../problems/maximum-subarray-sum-after-one-operation) | Medium |
-| <span id="1747">1747</span> | [Leetflex Banned Accounts](https://leetcode.com/problems/leetflex-banned-accounts "应该被禁止的Leetflex账户") 🔒 | [MySQL](../problems/leetflex-banned-accounts) | Medium |
-| <span id="1748">1748</span> | [Sum of Unique Elements](https://leetcode.com/problems/sum-of-unique-elements "唯一元素的和") | [Go](../problems/sum-of-unique-elements) | Easy |
-| <span id="1749">1749</span> | [Maximum Absolute Sum of Any Subarray](https://leetcode.com/problems/maximum-absolute-sum-of-any-subarray "任意子数组和的绝对值的最大值") | [Go](../problems/maximum-absolute-sum-of-any-subarray) | Medium |
-| <span id="1750">1750</span> | [Minimum Length of String After Deleting Similar Ends](https://leetcode.com/problems/minimum-length-of-string-after-deleting-similar-ends "删除字符串两端相同字符后的最短长度") | [Go](../problems/minimum-length-of-string-after-deleting-similar-ends) | Medium |
-| <span id="1751">1751</span> | [Maximum Number of Events That Can Be Attended II](https://leetcode.com/problems/maximum-number-of-events-that-can-be-attended-ii "最多可以参加的会议数目 II") | [Go](../problems/maximum-number-of-events-that-can-be-attended-ii) | Hard |
-| <span id="1752">1752</span> | [Check if Array Is Sorted and Rotated](https://leetcode.com/problems/check-if-array-is-sorted-and-rotated "检查数组是否经排序和轮转得到") | [Go](../problems/check-if-array-is-sorted-and-rotated) | Easy |
-| <span id="1753">1753</span> | [Maximum Score From Removing Stones](https://leetcode.com/problems/maximum-score-from-removing-stones "移除石子的最大得分") | [Go](../problems/maximum-score-from-removing-stones) | Medium |
-| <span id="1754">1754</span> | [Largest Merge Of Two Strings](https://leetcode.com/problems/largest-merge-of-two-strings "构造字典序最大的合并字符串") | [Go](../problems/largest-merge-of-two-strings) | Medium |
-| <span id="1755">1755</span> | [Closest Subsequence Sum](https://leetcode.com/problems/closest-subsequence-sum "最接近目标值的子序列和") | [Go](../problems/closest-subsequence-sum) | Hard |
-| <span id="1756">1756</span> | [Design Most Recently Used Queue](https://leetcode.com/problems/design-most-recently-used-queue "设计最近使用（MRU）队列") 🔒 | [Go](../problems/design-most-recently-used-queue) | Medium |
-| <span id="1757">1757</span> | [Recyclable and Low Fat Products](https://leetcode.com/problems/recyclable-and-low-fat-products "可回收且低脂的产品") 🔒 | [MySQL](../problems/recyclable-and-low-fat-products) | Easy |
-| <span id="1758">1758</span> | [Minimum Changes To Make Alternating Binary String](https://leetcode.com/problems/minimum-changes-to-make-alternating-binary-string "生成交替二进制字符串的最少操作数") | [Go](../problems/minimum-changes-to-make-alternating-binary-string) | Easy |
-| <span id="1759">1759</span> | [Count Number of Homogenous Substrings](https://leetcode.com/problems/count-number-of-homogenous-substrings "统计同构子字符串的数目") | [Go](../problems/count-number-of-homogenous-substrings) | Medium |
-| <span id="1760">1760</span> | [Minimum Limit of Balls in a Bag](https://leetcode.com/problems/minimum-limit-of-balls-in-a-bag "袋子里最少数目的球") | [Go](../problems/minimum-limit-of-balls-in-a-bag) | Medium |
-| <span id="1761">1761</span> | [Minimum Degree of a Connected Trio in a Graph](https://leetcode.com/problems/minimum-degree-of-a-connected-trio-in-a-graph "一个图中连通三元组的最小度数") | [Go](../problems/minimum-degree-of-a-connected-trio-in-a-graph) | Hard |
-| <span id="1762">1762</span> | [Buildings With an Ocean View](https://leetcode.com/problems/buildings-with-an-ocean-view "能看到海景的建筑物") 🔒 | [Go](../problems/buildings-with-an-ocean-view) | Medium |
-| <span id="1763">1763</span> | [Longest Nice Substring](https://leetcode.com/problems/longest-nice-substring "最长的美好子字符串") | [Go](../problems/longest-nice-substring) | Easy |
-| <span id="1764">1764</span> | [Form Array by Concatenating Subarrays of Another Array](https://leetcode.com/problems/form-array-by-concatenating-subarrays-of-another-array "通过连接另一个数组的子数组得到一个数组") | [Go](../problems/form-array-by-concatenating-subarrays-of-another-array) | Medium |
-| <span id="1765">1765</span> | [Map of Highest Peak](https://leetcode.com/problems/map-of-highest-peak "地图中的最高点") | [Go](../problems/map-of-highest-peak) | Medium |
-| <span id="1766">1766</span> | [Tree of Coprimes](https://leetcode.com/problems/tree-of-coprimes "互质树") | [Go](../problems/tree-of-coprimes) | Hard |
-| <span id="1767">1767</span> | [Find the Subtasks That Did Not Execute](https://leetcode.com/problems/find-the-subtasks-that-did-not-execute "寻找没有被执行的任务对") 🔒 | [MySQL](../problems/find-the-subtasks-that-did-not-execute) | Hard |
-| <span id="1768">1768</span> | [Merge Strings Alternately](https://leetcode.com/problems/merge-strings-alternately "交替合并字符串") | [Go](../problems/merge-strings-alternately) | Easy |
-| <span id="1769">1769</span> | [Minimum Number of Operations to Move All Balls to Each Box](https://leetcode.com/problems/minimum-number-of-operations-to-move-all-balls-to-each-box "移动所有球到每个盒子所需的最小操作数") | [Go](../problems/minimum-number-of-operations-to-move-all-balls-to-each-box) | Medium |
-| <span id="1770">1770</span> | [Maximum Score from Performing Multiplication Operations](https://leetcode.com/problems/maximum-score-from-performing-multiplication-operations "执行乘法运算的最大分数") | [Go](../problems/maximum-score-from-performing-multiplication-operations) | Medium |
-| <span id="1771">1771</span> | [Maximize Palindrome Length From Subsequences](https://leetcode.com/problems/maximize-palindrome-length-from-subsequences "由子序列构造的最长回文串的长度") | [Go](../problems/maximize-palindrome-length-from-subsequences) | Hard |
-| <span id="1772">1772</span> | [Sort Features by Popularity](https://leetcode.com/problems/sort-features-by-popularity "按受欢迎程度排列功能") 🔒 | [Go](../problems/sort-features-by-popularity) | Medium |
-| <span id="1773">1773</span> | [Count Items Matching a Rule](https://leetcode.com/problems/count-items-matching-a-rule "统计匹配检索规则的物品数量") | [Go](../problems/count-items-matching-a-rule) | Easy |
-| <span id="1774">1774</span> | [Closest Dessert Cost](https://leetcode.com/problems/closest-dessert-cost "最接近目标价格的甜点成本") | [Go](../problems/closest-dessert-cost) | Medium |
-| <span id="1775">1775</span> | [Equal Sum Arrays With Minimum Number of Operations](https://leetcode.com/problems/equal-sum-arrays-with-minimum-number-of-operations "通过最少操作次数使数组的和相等") | [Go](../problems/equal-sum-arrays-with-minimum-number-of-operations) | Medium |
-| <span id="1776">1776</span> | [Car Fleet II](https://leetcode.com/problems/car-fleet-ii "车队 II") | [Go](../problems/car-fleet-ii) | Hard |
-| <span id="1777">1777</span> | [Product's Price for Each Store](https://leetcode.com/problems/products-price-for-each-store "每家商店的产品价格") 🔒 | [MySQL](../problems/products-price-for-each-store) | Easy |
-| <span id="1778">1778</span> | [Shortest Path in a Hidden Grid](https://leetcode.com/problems/shortest-path-in-a-hidden-grid "未知网格中的最短路径") 🔒 | [Go](../problems/shortest-path-in-a-hidden-grid) | Medium |
-| <span id="1779">1779</span> | [Find Nearest Point That Has the Same X or Y Coordinate](https://leetcode.com/problems/find-nearest-point-that-has-the-same-x-or-y-coordinate "找到最近的有相同 X 或 Y 坐标的点") | [Go](../problems/find-nearest-point-that-has-the-same-x-or-y-coordinate) | Easy |
-| <span id="1780">1780</span> | [Check if Number is a Sum of Powers of Three](https://leetcode.com/problems/check-if-number-is-a-sum-of-powers-of-three "判断一个数字是否可以表示成三的幂的和") | [Go](../problems/check-if-number-is-a-sum-of-powers-of-three) | Medium |
-| <span id="1781">1781</span> | [Sum of Beauty of All Substrings](https://leetcode.com/problems/sum-of-beauty-of-all-substrings "所有子字符串美丽值之和") | [Go](../problems/sum-of-beauty-of-all-substrings) | Medium |
-| <span id="1782">1782</span> | [Count Pairs Of Nodes](https://leetcode.com/problems/count-pairs-of-nodes "统计点对的数目") | [Go](../problems/count-pairs-of-nodes) | Hard |
-| <span id="1783">1783</span> | [Grand Slam Titles](https://leetcode.com/problems/grand-slam-titles "大满贯数量") 🔒 | [MySQL](../problems/grand-slam-titles) | Medium |
-| <span id="1784">1784</span> | [Check if Binary String Has at Most One Segment of Ones](https://leetcode.com/problems/check-if-binary-string-has-at-most-one-segment-of-ones "检查二进制字符串字段") | [Go](../problems/check-if-binary-string-has-at-most-one-segment-of-ones) | Easy |
-| <span id="1785">1785</span> | [Minimum Elements to Add to Form a Given Sum](https://leetcode.com/problems/minimum-elements-to-add-to-form-a-given-sum "构成特定和需要添加的最少元素") | [Go](../problems/minimum-elements-to-add-to-form-a-given-sum) | Medium |
-| <span id="1786">1786</span> | [Number of Restricted Paths From First to Last Node](https://leetcode.com/problems/number-of-restricted-paths-from-first-to-last-node "从第一个节点出发到最后一个节点的受限路径数") | [Go](../problems/number-of-restricted-paths-from-first-to-last-node) | Medium |
-| <span id="1787">1787</span> | [Make the XOR of All Segments Equal to Zero](https://leetcode.com/problems/make-the-xor-of-all-segments-equal-to-zero "使所有区间的异或结果为零") | [Go](../problems/make-the-xor-of-all-segments-equal-to-zero) | Hard |
-| <span id="1788">1788</span> | [Maximize the Beauty of the Garden](https://leetcode.com/problems/maximize-the-beauty-of-the-garden "最大化花园的美观度") 🔒 | [Go](../problems/maximize-the-beauty-of-the-garden) | Hard |
-| <span id="1789">1789</span> | [Primary Department for Each Employee](https://leetcode.com/problems/primary-department-for-each-employee "员工的直属部门") 🔒 | [MySQL](../problems/primary-department-for-each-employee) | Easy |
-| <span id="1790">1790</span> | [Check if One String Swap Can Make Strings Equal](https://leetcode.com/problems/check-if-one-string-swap-can-make-strings-equal "仅执行一次字符串交换能否使两个字符串相等") | [Go](../problems/check-if-one-string-swap-can-make-strings-equal) | Easy |
-| <span id="1791">1791</span> | [Find Center of Star Graph](https://leetcode.com/problems/find-center-of-star-graph "找出星型图的中心节点") | [Go](../problems/find-center-of-star-graph) | Easy |
-| <span id="1792">1792</span> | [Maximum Average Pass Ratio](https://leetcode.com/problems/maximum-average-pass-ratio "最大平均通过率") | [Go](../problems/maximum-average-pass-ratio) | Medium |
-| <span id="1793">1793</span> | [Maximum Score of a Good Subarray](https://leetcode.com/problems/maximum-score-of-a-good-subarray "好子数组的最大分数") | [Go](../problems/maximum-score-of-a-good-subarray) | Hard |
-| <span id="1794">1794</span> | [Count Pairs of Equal Substrings With Minimum Difference](https://leetcode.com/problems/count-pairs-of-equal-substrings-with-minimum-difference "统计距离最小的子串对个数") 🔒 | [Go](../problems/count-pairs-of-equal-substrings-with-minimum-difference) | Medium |
-| <span id="1795">1795</span> | [Rearrange Products Table](https://leetcode.com/problems/rearrange-products-table "每个产品在不同商店的价格") 🔒 | [MySQL](../problems/rearrange-products-table) | Easy |
-| <span id="1796">1796</span> | [Second Largest Digit in a String](https://leetcode.com/problems/second-largest-digit-in-a-string "字符串中第二大的数字") | [Go](../problems/second-largest-digit-in-a-string) | Easy |
-| <span id="1797">1797</span> | [Design Authentication Manager](https://leetcode.com/problems/design-authentication-manager "设计一个验证系统") | [Go](../problems/design-authentication-manager) | Medium |
-| <span id="1798">1798</span> | [Maximum Number of Consecutive Values You Can Make](https://leetcode.com/problems/maximum-number-of-consecutive-values-you-can-make "你能构造出连续值的最大数目") | [Go](../problems/maximum-number-of-consecutive-values-you-can-make) | Medium |
-| <span id="1799">1799</span> | [Maximize Score After N Operations](https://leetcode.com/problems/maximize-score-after-n-operations "N 次操作后的最大分数和") | [Go](../problems/maximize-score-after-n-operations) | Hard |
-| <span id="1800">1800</span> | [Maximum Ascending Subarray Sum](https://leetcode.com/problems/maximum-ascending-subarray-sum "最大升序子数组和") | [Go](../problems/maximum-ascending-subarray-sum) | Easy |
diff --git a/readme/301-600.md b/readme/301-600.md
deleted file mode 100644
index 1a0e6f251..000000000
--- a/readme/301-600.md
+++ /dev/null
@@ -1,388 +0,0 @@
-<!--|This file generated by command(leetcode readme); DO NOT EDIT.         |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-# [LeetCode](https://awesee.github.io/leetcode)
-LeetCode Problems' Solutions
-[[力扣](https://awesee.github.io/categories/leetcode/) ∙ [话题分类](https://github.com/awesee/leetcode/blob/master/tag/README.md)]
-
-[![Go](https://github.com/awesee/leetcode/workflows/Go/badge.svg)](https://github.com/awesee/leetcode/actions)
-[![codecov](https://codecov.io/gh/awesee/leetcode/branch/master/graph/badge.svg)](https://codecov.io/gh/awesee/leetcode)
-[![Go Report Card](https://goreportcard.com/badge/github.com/awesee/leetcode)](https://goreportcard.com/report/github.com/awesee/leetcode)
-[![GitHub contributors](https://img.shields.io/github/contributors/awesee/leetcode.svg)](https://github.com/awesee/leetcode/graphs/contributors)
-[![license](https://img.shields.io/github/license/awesee/leetcode.svg)](https://github.com/awesee/leetcode/blob/master/LICENSE)
-[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fawesee%2Fleetcode.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fawesee%2Fleetcode?ref=badge_shield)
-[![Join the chat](https://badges.gitter.im/awesee/leetcode.svg)](https://gitter.im/awesee/leetcode?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-
-<table><thead>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#1">[1-50]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#51">[51-100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#101">[101-150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#151">[151-200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#201">[201-250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#251">[251-300]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#301">[301-350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#351">[351-400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#401">[401-450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#451">[451-500]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#501">[501-550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#551">[551-600]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#601">[601-650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#651">[651-700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#701">[701-750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#751">[751-800]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#801">[801-850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#851">[851-900]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#901">[901-950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#951">[951-1000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1001">[1001-1050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1051">[1051-1100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1101">[1101-1150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1151">[1151-1200]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1201">[1201-1250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1251">[1251-1300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1301">[1301-1350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1351">[1351-1400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1401">[1401-1450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1451">[1451-1500]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1501">[1501-1550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1551">[1551-1600]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1601">[1601-1650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1651">[1651-1700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1701">[1701-1750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1751">[1751-1800]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1850">[1801-1850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1900">[1851-1900]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1950">[1901-1950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2000">[1951-2000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2050">[2001-2050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2100">[2051-2100]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2150">[2101-2150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2200">[2151-2200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2250">[2201-2250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2300">[2251-2300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2350">[2301-2350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2400">[2351-2400]</a></th>
-</tr>
-</thead></table>
-
-| # | Title | Solution | Difficulty |
-| :-: | - | - | :-: |
-| <span id="301">301</span> | [Remove Invalid Parentheses](https://leetcode.com/problems/remove-invalid-parentheses "删除无效的括号") | [Go](../problems/remove-invalid-parentheses) | Hard |
-| <span id="302">302</span> | [Smallest Rectangle Enclosing Black Pixels](https://leetcode.com/problems/smallest-rectangle-enclosing-black-pixels "包含全部黑色像素的最小矩形") 🔒 | [Go](../problems/smallest-rectangle-enclosing-black-pixels) | Hard |
-| <span id="303">303</span> | [Range Sum Query - Immutable](https://leetcode.com/problems/range-sum-query-immutable "区域和检索 - 数组不可变") | [Go](../problems/range-sum-query-immutable) | Easy |
-| <span id="304">304</span> | [Range Sum Query 2D - Immutable](https://leetcode.com/problems/range-sum-query-2d-immutable "二维区域和检索 - 矩阵不可变") | [Go](../problems/range-sum-query-2d-immutable) | Medium |
-| <span id="305">305</span> | [Number of Islands II](https://leetcode.com/problems/number-of-islands-ii "岛屿数量 II") 🔒 | [Go](../problems/number-of-islands-ii) | Hard |
-| <span id="306">306</span> | [Additive Number](https://leetcode.com/problems/additive-number "累加数") | [Go](../problems/additive-number) | Medium |
-| <span id="307">307</span> | [Range Sum Query - Mutable](https://leetcode.com/problems/range-sum-query-mutable "区域和检索 - 数组可修改") | [Go](../problems/range-sum-query-mutable) | Medium |
-| <span id="308">308</span> | [Range Sum Query 2D - Mutable](https://leetcode.com/problems/range-sum-query-2d-mutable "二维区域和检索 - 可变") 🔒 | [Go](../problems/range-sum-query-2d-mutable) | Hard |
-| <span id="309">309</span> | [Best Time to Buy and Sell Stock with Cooldown](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown "最佳买卖股票时机含冷冻期") | [Go](../problems/best-time-to-buy-and-sell-stock-with-cooldown) | Medium |
-| <span id="310">310</span> | [Minimum Height Trees](https://leetcode.com/problems/minimum-height-trees "最小高度树") | [Go](../problems/minimum-height-trees) | Medium |
-| <span id="311">311</span> | [Sparse Matrix Multiplication](https://leetcode.com/problems/sparse-matrix-multiplication "稀疏矩阵的乘法") 🔒 | [Go](../problems/sparse-matrix-multiplication) | Medium |
-| <span id="312">312</span> | [Burst Balloons](https://leetcode.com/problems/burst-balloons "戳气球") | [Go](../problems/burst-balloons) | Hard |
-| <span id="313">313</span> | [Super Ugly Number](https://leetcode.com/problems/super-ugly-number "超级丑数") | [Go](../problems/super-ugly-number) | Medium |
-| <span id="314">314</span> | [Binary Tree Vertical Order Traversal](https://leetcode.com/problems/binary-tree-vertical-order-traversal "二叉树的垂直遍历") 🔒 | [Go](../problems/binary-tree-vertical-order-traversal) | Medium |
-| <span id="315">315</span> | [Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self "计算右侧小于当前元素的个数") | [Go](../problems/count-of-smaller-numbers-after-self) | Hard |
-| <span id="316">316</span> | [Remove Duplicate Letters](https://leetcode.com/problems/remove-duplicate-letters "去除重复字母") | [Go](../problems/remove-duplicate-letters) | Medium |
-| <span id="317">317</span> | [Shortest Distance from All Buildings](https://leetcode.com/problems/shortest-distance-from-all-buildings "离建筑物最近的距离") 🔒 | [Go](../problems/shortest-distance-from-all-buildings) | Hard |
-| <span id="318">318</span> | [Maximum Product of Word Lengths](https://leetcode.com/problems/maximum-product-of-word-lengths "最大单词长度乘积") | [Go](../problems/maximum-product-of-word-lengths) | Medium |
-| <span id="319">319</span> | [Bulb Switcher](https://leetcode.com/problems/bulb-switcher "灯泡开关") | [Go](../problems/bulb-switcher) | Medium |
-| <span id="320">320</span> | [Generalized Abbreviation](https://leetcode.com/problems/generalized-abbreviation "列举单词的全部缩写") 🔒 | [Go](../problems/generalized-abbreviation) | Medium |
-| <span id="321">321</span> | [Create Maximum Number](https://leetcode.com/problems/create-maximum-number "拼接最大数") | [Go](../problems/create-maximum-number) | Hard |
-| <span id="322">322</span> | [Coin Change](https://leetcode.com/problems/coin-change "零钱兑换") | [Go](../problems/coin-change) | Medium |
-| <span id="323">323</span> | [Number of Connected Components in an Undirected Graph](https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph "无向图中连通分量的数目") 🔒 | [Go](../problems/number-of-connected-components-in-an-undirected-graph) | Medium |
-| <span id="324">324</span> | [Wiggle Sort II](https://leetcode.com/problems/wiggle-sort-ii "摆动排序 II") | [Go](../problems/wiggle-sort-ii) | Medium |
-| <span id="325">325</span> | [Maximum Size Subarray Sum Equals k](https://leetcode.com/problems/maximum-size-subarray-sum-equals-k "和等于 k 的最长子数组长度") 🔒 | [Go](../problems/maximum-size-subarray-sum-equals-k) | Medium |
-| <span id="326">326</span> | [Power of Three](https://leetcode.com/problems/power-of-three "3 的幂") | [Go](../problems/power-of-three) | Easy |
-| <span id="327">327</span> | [Count of Range Sum](https://leetcode.com/problems/count-of-range-sum "区间和的个数") | [Go](../problems/count-of-range-sum) | Hard |
-| <span id="328">328</span> | [Odd Even Linked List](https://leetcode.com/problems/odd-even-linked-list "奇偶链表") | [Go](../problems/odd-even-linked-list) | Medium |
-| <span id="329">329</span> | [Longest Increasing Path in a Matrix](https://leetcode.com/problems/longest-increasing-path-in-a-matrix "矩阵中的最长递增路径") | [Go](../problems/longest-increasing-path-in-a-matrix) | Hard |
-| <span id="330">330</span> | [Patching Array](https://leetcode.com/problems/patching-array "按要求补齐数组") | [Go](../problems/patching-array) | Hard |
-| <span id="331">331</span> | [Verify Preorder Serialization of a Binary Tree](https://leetcode.com/problems/verify-preorder-serialization-of-a-binary-tree "验证二叉树的前序序列化") | [Go](../problems/verify-preorder-serialization-of-a-binary-tree) | Medium |
-| <span id="332">332</span> | [Reconstruct Itinerary](https://leetcode.com/problems/reconstruct-itinerary "重新安排行程") | [Go](../problems/reconstruct-itinerary) | Hard |
-| <span id="333">333</span> | [Largest BST Subtree](https://leetcode.com/problems/largest-bst-subtree "最大 BST 子树") 🔒 | [Go](../problems/largest-bst-subtree) | Medium |
-| <span id="334">334</span> | [Increasing Triplet Subsequence](https://leetcode.com/problems/increasing-triplet-subsequence "递增的三元子序列") | [Go](../problems/increasing-triplet-subsequence) | Medium |
-| <span id="335">335</span> | [Self Crossing](https://leetcode.com/problems/self-crossing "路径交叉") | [Go](../problems/self-crossing) | Hard |
-| <span id="336">336</span> | [Palindrome Pairs](https://leetcode.com/problems/palindrome-pairs "回文对") | [Go](../problems/palindrome-pairs) | Hard |
-| <span id="337">337</span> | [House Robber III](https://leetcode.com/problems/house-robber-iii "打家劫舍 III") | [Go](../problems/house-robber-iii) | Medium |
-| <span id="338">338</span> | [Counting Bits](https://leetcode.com/problems/counting-bits "比特位计数") | [Go](../problems/counting-bits) | Easy |
-| <span id="339">339</span> | [Nested List Weight Sum](https://leetcode.com/problems/nested-list-weight-sum "嵌套列表权重和") 🔒 | [Go](../problems/nested-list-weight-sum) | Medium |
-| <span id="340">340</span> | [Longest Substring with At Most K Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters "至多包含 K 个不同字符的最长子串") 🔒 | [Go](../problems/longest-substring-with-at-most-k-distinct-characters) | Medium |
-| <span id="341">341</span> | [Flatten Nested List Iterator](https://leetcode.com/problems/flatten-nested-list-iterator "扁平化嵌套列表迭代器") | [Go](../problems/flatten-nested-list-iterator) | Medium |
-| <span id="342">342</span> | [Power of Four](https://leetcode.com/problems/power-of-four "4的幂") | [Go](../problems/power-of-four) | Easy |
-| <span id="343">343</span> | [Integer Break](https://leetcode.com/problems/integer-break "整数拆分") | [Go](../problems/integer-break) | Medium |
-| <span id="344">344</span> | [Reverse String](https://leetcode.com/problems/reverse-string "反转字符串") | [Go](../problems/reverse-string) | Easy |
-| <span id="345">345</span> | [Reverse Vowels of a String](https://leetcode.com/problems/reverse-vowels-of-a-string "反转字符串中的元音字母") | [Go](../problems/reverse-vowels-of-a-string) | Easy |
-| <span id="346">346</span> | [Moving Average from Data Stream](https://leetcode.com/problems/moving-average-from-data-stream "数据流中的移动平均值") 🔒 | [Go](../problems/moving-average-from-data-stream) | Easy |
-| <span id="347">347</span> | [Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements "前 K 个高频元素") | [Go](../problems/top-k-frequent-elements) | Medium |
-| <span id="348">348</span> | [Design Tic-Tac-Toe](https://leetcode.com/problems/design-tic-tac-toe "设计井字棋") 🔒 | [Go](../problems/design-tic-tac-toe) | Medium |
-| <span id="349">349</span> | [Intersection of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays "两个数组的交集") | [Go](../problems/intersection-of-two-arrays) | Easy |
-| <span id="350">350</span> | [Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii "两个数组的交集 II") | [Go](../problems/intersection-of-two-arrays-ii) | Easy |
-| <span id="351">351</span> | [Android Unlock Patterns](https://leetcode.com/problems/android-unlock-patterns "安卓系统手势解锁") 🔒 | [Go](../problems/android-unlock-patterns) | Medium |
-| <span id="352">352</span> | [Data Stream as Disjoint Intervals](https://leetcode.com/problems/data-stream-as-disjoint-intervals "将数据流变为多个不相交区间") | [Go](../problems/data-stream-as-disjoint-intervals) | Hard |
-| <span id="353">353</span> | [Design Snake Game](https://leetcode.com/problems/design-snake-game "贪吃蛇") 🔒 | [Go](../problems/design-snake-game) | Medium |
-| <span id="354">354</span> | [Russian Doll Envelopes](https://leetcode.com/problems/russian-doll-envelopes "俄罗斯套娃信封问题") | [Go](../problems/russian-doll-envelopes) | Hard |
-| <span id="355">355</span> | [Design Twitter](https://leetcode.com/problems/design-twitter "设计推特") | [Go](../problems/design-twitter) | Medium |
-| <span id="356">356</span> | [Line Reflection](https://leetcode.com/problems/line-reflection "直线镜像") 🔒 | [Go](../problems/line-reflection) | Medium |
-| <span id="357">357</span> | [Count Numbers with Unique Digits](https://leetcode.com/problems/count-numbers-with-unique-digits "计算各个位数不同的数字个数") | [Go](../problems/count-numbers-with-unique-digits) | Medium |
-| <span id="358">358</span> | [Rearrange String k Distance Apart](https://leetcode.com/problems/rearrange-string-k-distance-apart "K 距离间隔重排字符串") 🔒 | [Go](../problems/rearrange-string-k-distance-apart) | Hard |
-| <span id="359">359</span> | [Logger Rate Limiter](https://leetcode.com/problems/logger-rate-limiter "日志速率限制器") 🔒 | [Go](../problems/logger-rate-limiter) | Easy |
-| <span id="360">360</span> | [Sort Transformed Array](https://leetcode.com/problems/sort-transformed-array "有序转化数组") 🔒 | [Go](../problems/sort-transformed-array) | Medium |
-| <span id="361">361</span> | [Bomb Enemy](https://leetcode.com/problems/bomb-enemy "轰炸敌人") 🔒 | [Go](../problems/bomb-enemy) | Medium |
-| <span id="362">362</span> | [Design Hit Counter](https://leetcode.com/problems/design-hit-counter "敲击计数器") 🔒 | [Go](../problems/design-hit-counter) | Medium |
-| <span id="363">363</span> | [Max Sum of Rectangle No Larger Than K](https://leetcode.com/problems/max-sum-of-rectangle-no-larger-than-k "矩形区域不超过 K 的最大数值和") | [Go](../problems/max-sum-of-rectangle-no-larger-than-k) | Hard |
-| <span id="364">364</span> | [Nested List Weight Sum II](https://leetcode.com/problems/nested-list-weight-sum-ii "加权嵌套序列和 II") 🔒 | [Go](../problems/nested-list-weight-sum-ii) | Medium |
-| <span id="365">365</span> | [Water and Jug Problem](https://leetcode.com/problems/water-and-jug-problem "水壶问题") | [Go](../problems/water-and-jug-problem) | Medium |
-| <span id="366">366</span> | [Find Leaves of Binary Tree](https://leetcode.com/problems/find-leaves-of-binary-tree "寻找二叉树的叶子节点") 🔒 | [Go](../problems/find-leaves-of-binary-tree) | Medium |
-| <span id="367">367</span> | [Valid Perfect Square](https://leetcode.com/problems/valid-perfect-square "有效的完全平方数") | [Go](../problems/valid-perfect-square) | Easy |
-| <span id="368">368</span> | [Largest Divisible Subset](https://leetcode.com/problems/largest-divisible-subset "最大整除子集") | [Go](../problems/largest-divisible-subset) | Medium |
-| <span id="369">369</span> | [Plus One Linked List](https://leetcode.com/problems/plus-one-linked-list "给单链表加一") 🔒 | [Go](../problems/plus-one-linked-list) | Medium |
-| <span id="370">370</span> | [Range Addition](https://leetcode.com/problems/range-addition "区间加法") 🔒 | [Go](../problems/range-addition) | Medium |
-| <span id="371">371</span> | [Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers "两整数之和") | [Go](../problems/sum-of-two-integers) | Medium |
-| <span id="372">372</span> | [Super Pow](https://leetcode.com/problems/super-pow "超级次方") | [Go](../problems/super-pow) | Medium |
-| <span id="373">373</span> | [Find K Pairs with Smallest Sums](https://leetcode.com/problems/find-k-pairs-with-smallest-sums "查找和最小的 K 对数字") | [Go](../problems/find-k-pairs-with-smallest-sums) | Medium |
-| <span id="374">374</span> | [Guess Number Higher or Lower](https://leetcode.com/problems/guess-number-higher-or-lower "猜数字大小") | [Go](../problems/guess-number-higher-or-lower) | Easy |
-| <span id="375">375</span> | [Guess Number Higher or Lower II](https://leetcode.com/problems/guess-number-higher-or-lower-ii "猜数字大小 II") | [Go](../problems/guess-number-higher-or-lower-ii) | Medium |
-| <span id="376">376</span> | [Wiggle Subsequence](https://leetcode.com/problems/wiggle-subsequence "摆动序列") | [Go](../problems/wiggle-subsequence) | Medium |
-| <span id="377">377</span> | [Combination Sum IV](https://leetcode.com/problems/combination-sum-iv "组合总和 Ⅳ") | [Go](../problems/combination-sum-iv) | Medium |
-| <span id="378">378</span> | [Kth Smallest Element in a Sorted Matrix](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix "有序矩阵中第 K 小的元素") | [Go](../problems/kth-smallest-element-in-a-sorted-matrix) | Medium |
-| <span id="379">379</span> | [Design Phone Directory](https://leetcode.com/problems/design-phone-directory "电话目录管理系统") 🔒 | [Go](../problems/design-phone-directory) | Medium |
-| <span id="380">380</span> | [Insert Delete GetRandom O(1)](https://leetcode.com/problems/insert-delete-getrandom-o1 "O(1) 时间插入、删除和获取随机元素") | [Go](../problems/insert-delete-getrandom-o1) | Medium |
-| <span id="381">381</span> | [Insert Delete GetRandom O(1) - Duplicates allowed](https://leetcode.com/problems/insert-delete-getrandom-o1-duplicates-allowed "O(1) 时间插入、删除和获取随机元素 - 允许重复") | [Go](../problems/insert-delete-getrandom-o1-duplicates-allowed) | Hard |
-| <span id="382">382</span> | [Linked List Random Node](https://leetcode.com/problems/linked-list-random-node "链表随机节点") | [Go](../problems/linked-list-random-node) | Medium |
-| <span id="383">383</span> | [Ransom Note](https://leetcode.com/problems/ransom-note "赎金信") | [Go](../problems/ransom-note) | Easy |
-| <span id="384">384</span> | [Shuffle an Array](https://leetcode.com/problems/shuffle-an-array "打乱数组") | [Go](../problems/shuffle-an-array) | Medium |
-| <span id="385">385</span> | [Mini Parser](https://leetcode.com/problems/mini-parser "迷你语法分析器") | [Go](../problems/mini-parser) | Medium |
-| <span id="386">386</span> | [Lexicographical Numbers](https://leetcode.com/problems/lexicographical-numbers "字典序排数") | [Go](../problems/lexicographical-numbers) | Medium |
-| <span id="387">387</span> | [First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string "字符串中的第一个唯一字符") | [Go](../problems/first-unique-character-in-a-string) | Easy |
-| <span id="388">388</span> | [Longest Absolute File Path](https://leetcode.com/problems/longest-absolute-file-path "文件的最长绝对路径") | [Go](../problems/longest-absolute-file-path) | Medium |
-| <span id="389">389</span> | [Find the Difference](https://leetcode.com/problems/find-the-difference "找不同") | [Go](../problems/find-the-difference) | Easy |
-| <span id="390">390</span> | [Elimination Game](https://leetcode.com/problems/elimination-game "消除游戏") | [Go](../problems/elimination-game) | Medium |
-| <span id="391">391</span> | [Perfect Rectangle](https://leetcode.com/problems/perfect-rectangle "完美矩形") | [Go](../problems/perfect-rectangle) | Hard |
-| <span id="392">392</span> | [Is Subsequence](https://leetcode.com/problems/is-subsequence "判断子序列") | [Go](../problems/is-subsequence) | Easy |
-| <span id="393">393</span> | [UTF-8 Validation](https://leetcode.com/problems/utf-8-validation "UTF-8 编码验证") | [Go](../problems/utf-8-validation) | Medium |
-| <span id="394">394</span> | [Decode String](https://leetcode.com/problems/decode-string "字符串解码") | [Go](../problems/decode-string) | Medium |
-| <span id="395">395</span> | [Longest Substring with At Least K Repeating Characters](https://leetcode.com/problems/longest-substring-with-at-least-k-repeating-characters "至少有 K 个重复字符的最长子串") | [Go](../problems/longest-substring-with-at-least-k-repeating-characters) | Medium |
-| <span id="396">396</span> | [Rotate Function](https://leetcode.com/problems/rotate-function "旋转函数") | [Go](../problems/rotate-function) | Medium |
-| <span id="397">397</span> | [Integer Replacement](https://leetcode.com/problems/integer-replacement "整数替换") | [Go](../problems/integer-replacement) | Medium |
-| <span id="398">398</span> | [Random Pick Index](https://leetcode.com/problems/random-pick-index "随机数索引") | [Go](../problems/random-pick-index) | Medium |
-| <span id="399">399</span> | [Evaluate Division](https://leetcode.com/problems/evaluate-division "除法求值") | [Go](../problems/evaluate-division) | Medium |
-| <span id="400">400</span> | [Nth Digit](https://leetcode.com/problems/nth-digit "第 N 位数字") | [Go](../problems/nth-digit) | Medium |
-| <span id="401">401</span> | [Binary Watch](https://leetcode.com/problems/binary-watch "二进制手表") | [Go](../problems/binary-watch) | Easy |
-| <span id="402">402</span> | [Remove K Digits](https://leetcode.com/problems/remove-k-digits "移掉 K 位数字") | [Go](../problems/remove-k-digits) | Medium |
-| <span id="403">403</span> | [Frog Jump](https://leetcode.com/problems/frog-jump "青蛙过河") | [Go](../problems/frog-jump) | Hard |
-| <span id="404">404</span> | [Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves "左叶子之和") | [Go](../problems/sum-of-left-leaves) | Easy |
-| <span id="405">405</span> | [Convert a Number to Hexadecimal](https://leetcode.com/problems/convert-a-number-to-hexadecimal "数字转换为十六进制数") | [Go](../problems/convert-a-number-to-hexadecimal) | Easy |
-| <span id="406">406</span> | [Queue Reconstruction by Height](https://leetcode.com/problems/queue-reconstruction-by-height "根据身高重建队列") | [Go](../problems/queue-reconstruction-by-height) | Medium |
-| <span id="407">407</span> | [Trapping Rain Water II](https://leetcode.com/problems/trapping-rain-water-ii "接雨水 II") | [Go](../problems/trapping-rain-water-ii) | Hard |
-| <span id="408">408</span> | [Valid Word Abbreviation](https://leetcode.com/problems/valid-word-abbreviation "有效单词缩写") 🔒 | [Go](../problems/valid-word-abbreviation) | Easy |
-| <span id="409">409</span> | [Longest Palindrome](https://leetcode.com/problems/longest-palindrome "最长回文串") | [Go](../problems/longest-palindrome) | Easy |
-| <span id="410">410</span> | [Split Array Largest Sum](https://leetcode.com/problems/split-array-largest-sum "分割数组的最大值") | [Go](../problems/split-array-largest-sum) | Hard |
-| <span id="411">411</span> | [Minimum Unique Word Abbreviation](https://leetcode.com/problems/minimum-unique-word-abbreviation "最短独占单词缩写") 🔒 | [Go](../problems/minimum-unique-word-abbreviation) | Hard |
-| <span id="412">412</span> | [Fizz Buzz](https://leetcode.com/problems/fizz-buzz "Fizz Buzz") | [Go](../problems/fizz-buzz) | Easy |
-| <span id="413">413</span> | [Arithmetic Slices](https://leetcode.com/problems/arithmetic-slices "等差数列划分") | [Go](../problems/arithmetic-slices) | Medium |
-| <span id="414">414</span> | [Third Maximum Number](https://leetcode.com/problems/third-maximum-number "第三大的数") | [Go](../problems/third-maximum-number) | Easy |
-| <span id="415">415</span> | [Add Strings](https://leetcode.com/problems/add-strings "字符串相加") | [Go](../problems/add-strings) | Easy |
-| <span id="416">416</span> | [Partition Equal Subset Sum](https://leetcode.com/problems/partition-equal-subset-sum "分割等和子集") | [Go](../problems/partition-equal-subset-sum) | Medium |
-| <span id="417">417</span> | [Pacific Atlantic Water Flow](https://leetcode.com/problems/pacific-atlantic-water-flow "太平洋大西洋水流问题") | [Go](../problems/pacific-atlantic-water-flow) | Medium |
-| <span id="418">418</span> | [Sentence Screen Fitting](https://leetcode.com/problems/sentence-screen-fitting "屏幕可显示句子的数量") 🔒 | [Go](../problems/sentence-screen-fitting) | Medium |
-| <span id="419">419</span> | [Battleships in a Board](https://leetcode.com/problems/battleships-in-a-board "甲板上的战舰") | [Go](../problems/battleships-in-a-board) | Medium |
-| <span id="420">420</span> | [Strong Password Checker](https://leetcode.com/problems/strong-password-checker "强密码检验器") | [Go](../problems/strong-password-checker) | Hard |
-| <span id="421">421</span> | [Maximum XOR of Two Numbers in an Array](https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array "数组中两个数的最大异或值") | [Go](../problems/maximum-xor-of-two-numbers-in-an-array) | Medium |
-| <span id="422">422</span> | [Valid Word Square](https://leetcode.com/problems/valid-word-square "有效的单词方块") 🔒 | [Go](../problems/valid-word-square) | Easy |
-| <span id="423">423</span> | [Reconstruct Original Digits from English](https://leetcode.com/problems/reconstruct-original-digits-from-english "从英文中重建数字") | [Go](../problems/reconstruct-original-digits-from-english) | Medium |
-| <span id="424">424</span> | [Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement "替换后的最长重复字符") | [Go](../problems/longest-repeating-character-replacement) | Medium |
-| <span id="425">425</span> | [Word Squares](https://leetcode.com/problems/word-squares "单词方块") 🔒 | [Go](../problems/word-squares) | Hard |
-| <span id="426">426</span> | [Convert Binary Search Tree to Sorted Doubly Linked List](https://leetcode.com/problems/convert-binary-search-tree-to-sorted-doubly-linked-list "将二叉搜索树转化为排序的双向链表") 🔒 | [Go](../problems/convert-binary-search-tree-to-sorted-doubly-linked-list) | Medium |
-| <span id="427">427</span> | [Construct Quad Tree](https://leetcode.com/problems/construct-quad-tree "建立四叉树") | [Go](../problems/construct-quad-tree) | Medium |
-| <span id="428">428</span> | [Serialize and Deserialize N-ary Tree](https://leetcode.com/problems/serialize-and-deserialize-n-ary-tree "序列化和反序列化 N 叉树") 🔒 | [Go](../problems/serialize-and-deserialize-n-ary-tree) | Hard |
-| <span id="429">429</span> | [N-ary Tree Level Order Traversal](https://leetcode.com/problems/n-ary-tree-level-order-traversal "N 叉树的层序遍历") | [Go](../problems/n-ary-tree-level-order-traversal) | Medium |
-| <span id="430">430</span> | [Flatten a Multilevel Doubly Linked List](https://leetcode.com/problems/flatten-a-multilevel-doubly-linked-list "扁平化多级双向链表") | [Go](../problems/flatten-a-multilevel-doubly-linked-list) | Medium |
-| <span id="431">431</span> | [Encode N-ary Tree to Binary Tree](https://leetcode.com/problems/encode-n-ary-tree-to-binary-tree "将 N 叉树编码为二叉树") 🔒 | [Go](../problems/encode-n-ary-tree-to-binary-tree) | Hard |
-| <span id="432">432</span> | [All O`one Data Structure](https://leetcode.com/problems/all-oone-data-structure "全 O(1) 的数据结构") | [Go](../problems/all-oone-data-structure) | Hard |
-| <span id="433">433</span> | [Minimum Genetic Mutation](https://leetcode.com/problems/minimum-genetic-mutation "最小基因变化") | [Go](../problems/minimum-genetic-mutation) | Medium |
-| <span id="434">434</span> | [Number of Segments in a String](https://leetcode.com/problems/number-of-segments-in-a-string "字符串中的单词数") | [Go](../problems/number-of-segments-in-a-string) | Easy |
-| <span id="435">435</span> | [Non-overlapping Intervals](https://leetcode.com/problems/non-overlapping-intervals "无重叠区间") | [Go](../problems/non-overlapping-intervals) | Medium |
-| <span id="436">436</span> | [Find Right Interval](https://leetcode.com/problems/find-right-interval "寻找右区间") | [Go](../problems/find-right-interval) | Medium |
-| <span id="437">437</span> | [Path Sum III](https://leetcode.com/problems/path-sum-iii "路径总和 III") | [Go](../problems/path-sum-iii) | Medium |
-| <span id="438">438</span> | [Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string "找到字符串中所有字母异位词") | [Go](../problems/find-all-anagrams-in-a-string) | Medium |
-| <span id="439">439</span> | [Ternary Expression Parser](https://leetcode.com/problems/ternary-expression-parser "三元表达式解析器") 🔒 | [Go](../problems/ternary-expression-parser) | Medium |
-| <span id="440">440</span> | [K-th Smallest in Lexicographical Order](https://leetcode.com/problems/k-th-smallest-in-lexicographical-order "字典序的第K小数字") | [Go](../problems/k-th-smallest-in-lexicographical-order) | Hard |
-| <span id="441">441</span> | [Arranging Coins](https://leetcode.com/problems/arranging-coins "排列硬币") | [Go](../problems/arranging-coins) | Easy |
-| <span id="442">442</span> | [Find All Duplicates in an Array](https://leetcode.com/problems/find-all-duplicates-in-an-array "数组中重复的数据") | [Go](../problems/find-all-duplicates-in-an-array) | Medium |
-| <span id="443">443</span> | [String Compression](https://leetcode.com/problems/string-compression "压缩字符串") | [Go](../problems/string-compression) | Medium |
-| <span id="444">444</span> | [Sequence Reconstruction](https://leetcode.com/problems/sequence-reconstruction "序列重建") 🔒 | [Go](../problems/sequence-reconstruction) | Medium |
-| <span id="445">445</span> | [Add Two Numbers II](https://leetcode.com/problems/add-two-numbers-ii "两数相加 II") | [Go](../problems/add-two-numbers-ii) | Medium |
-| <span id="446">446</span> | [Arithmetic Slices II - Subsequence](https://leetcode.com/problems/arithmetic-slices-ii-subsequence "等差数列划分 II - 子序列") | [Go](../problems/arithmetic-slices-ii-subsequence) | Hard |
-| <span id="447">447</span> | [Number of Boomerangs](https://leetcode.com/problems/number-of-boomerangs "回旋镖的数量") | [Go](../problems/number-of-boomerangs) | Medium |
-| <span id="448">448</span> | [Find All Numbers Disappeared in an Array](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array "找到所有数组中消失的数字") | [Go](../problems/find-all-numbers-disappeared-in-an-array) | Easy |
-| <span id="449">449</span> | [Serialize and Deserialize BST](https://leetcode.com/problems/serialize-and-deserialize-bst "序列化和反序列化二叉搜索树") | [Go](../problems/serialize-and-deserialize-bst) | Medium |
-| <span id="450">450</span> | [Delete Node in a BST](https://leetcode.com/problems/delete-node-in-a-bst "删除二叉搜索树中的节点") | [Go](../problems/delete-node-in-a-bst) | Medium |
-| <span id="451">451</span> | [Sort Characters By Frequency](https://leetcode.com/problems/sort-characters-by-frequency "根据字符出现频率排序") | [Go](../problems/sort-characters-by-frequency) | Medium |
-| <span id="452">452</span> | [Minimum Number of Arrows to Burst Balloons](https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons "用最少数量的箭引爆气球") | [Go](../problems/minimum-number-of-arrows-to-burst-balloons) | Medium |
-| <span id="453">453</span> | [Minimum Moves to Equal Array Elements](https://leetcode.com/problems/minimum-moves-to-equal-array-elements "最小操作次数使数组元素相等") | [Go](../problems/minimum-moves-to-equal-array-elements) | Medium |
-| <span id="454">454</span> | [4Sum II](https://leetcode.com/problems/4sum-ii "四数相加 II") | [Go](../problems/4sum-ii) | Medium |
-| <span id="455">455</span> | [Assign Cookies](https://leetcode.com/problems/assign-cookies "分发饼干") | [Go](../problems/assign-cookies) | Easy |
-| <span id="456">456</span> | [132 Pattern](https://leetcode.com/problems/132-pattern "132 模式") | [Go](../problems/132-pattern) | Medium |
-| <span id="457">457</span> | [Circular Array Loop](https://leetcode.com/problems/circular-array-loop "环形数组是否存在循环") | [Go](../problems/circular-array-loop) | Medium |
-| <span id="458">458</span> | [Poor Pigs](https://leetcode.com/problems/poor-pigs "可怜的小猪") | [Go](../problems/poor-pigs) | Hard |
-| <span id="459">459</span> | [Repeated Substring Pattern](https://leetcode.com/problems/repeated-substring-pattern "重复的子字符串") | [Go](../problems/repeated-substring-pattern) | Easy |
-| <span id="460">460</span> | [LFU Cache](https://leetcode.com/problems/lfu-cache "LFU 缓存") | [Go](../problems/lfu-cache) | Hard |
-| <span id="461">461</span> | [Hamming Distance](https://leetcode.com/problems/hamming-distance "汉明距离") | [Go](../problems/hamming-distance) | Easy |
-| <span id="462">462</span> | [Minimum Moves to Equal Array Elements II](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii "最少移动次数使数组元素相等 II") | [Go](../problems/minimum-moves-to-equal-array-elements-ii) | Medium |
-| <span id="463">463</span> | [Island Perimeter](https://leetcode.com/problems/island-perimeter "岛屿的周长") | [Go](../problems/island-perimeter) | Easy |
-| <span id="464">464</span> | [Can I Win](https://leetcode.com/problems/can-i-win "我能赢吗") | [Go](../problems/can-i-win) | Medium |
-| <span id="465">465</span> | [Optimal Account Balancing](https://leetcode.com/problems/optimal-account-balancing "最优账单平衡") 🔒 | [Go](../problems/optimal-account-balancing) | Hard |
-| <span id="466">466</span> | [Count The Repetitions](https://leetcode.com/problems/count-the-repetitions "统计重复个数") | [Go](../problems/count-the-repetitions) | Hard |
-| <span id="467">467</span> | [Unique Substrings in Wraparound String](https://leetcode.com/problems/unique-substrings-in-wraparound-string "环绕字符串中唯一的子字符串") | [Go](../problems/unique-substrings-in-wraparound-string) | Medium |
-| <span id="468">468</span> | [Validate IP Address](https://leetcode.com/problems/validate-ip-address "验证IP地址") | [Go](../problems/validate-ip-address) | Medium |
-| <span id="469">469</span> | [Convex Polygon](https://leetcode.com/problems/convex-polygon "凸多边形") 🔒 | [Go](../problems/convex-polygon) | Medium |
-| <span id="470">470</span> | [Implement Rand10() Using Rand7()](https://leetcode.com/problems/implement-rand10-using-rand7 "用 Rand7() 实现 Rand10()") | [Go](../problems/implement-rand10-using-rand7) | Medium |
-| <span id="471">471</span> | [Encode String with Shortest Length](https://leetcode.com/problems/encode-string-with-shortest-length "编码最短长度的字符串") 🔒 | [Go](../problems/encode-string-with-shortest-length) | Hard |
-| <span id="472">472</span> | [Concatenated Words](https://leetcode.com/problems/concatenated-words "连接词") | [Go](../problems/concatenated-words) | Hard |
-| <span id="473">473</span> | [Matchsticks to Square](https://leetcode.com/problems/matchsticks-to-square "火柴拼正方形") | [Go](../problems/matchsticks-to-square) | Medium |
-| <span id="474">474</span> | [Ones and Zeroes](https://leetcode.com/problems/ones-and-zeroes "一和零") | [Go](../problems/ones-and-zeroes) | Medium |
-| <span id="475">475</span> | [Heaters](https://leetcode.com/problems/heaters "供暖器") | [Go](../problems/heaters) | Medium |
-| <span id="476">476</span> | [Number Complement](https://leetcode.com/problems/number-complement "数字的补数") | [Go](../problems/number-complement) | Easy |
-| <span id="477">477</span> | [Total Hamming Distance](https://leetcode.com/problems/total-hamming-distance "汉明距离总和") | [Go](../problems/total-hamming-distance) | Medium |
-| <span id="478">478</span> | [Generate Random Point in a Circle](https://leetcode.com/problems/generate-random-point-in-a-circle "在圆内随机生成点") | [Go](../problems/generate-random-point-in-a-circle) | Medium |
-| <span id="479">479</span> | [Largest Palindrome Product](https://leetcode.com/problems/largest-palindrome-product "最大回文数乘积") | [Go](../problems/largest-palindrome-product) | Hard |
-| <span id="480">480</span> | [Sliding Window Median](https://leetcode.com/problems/sliding-window-median "滑动窗口中位数") | [Go](../problems/sliding-window-median) | Hard |
-| <span id="481">481</span> | [Magical String](https://leetcode.com/problems/magical-string "神奇字符串") | [Go](../problems/magical-string) | Medium |
-| <span id="482">482</span> | [License Key Formatting](https://leetcode.com/problems/license-key-formatting "密钥格式化") | [Go](../problems/license-key-formatting) | Easy |
-| <span id="483">483</span> | [Smallest Good Base](https://leetcode.com/problems/smallest-good-base "最小好进制") | [Go](../problems/smallest-good-base) | Hard |
-| <span id="484">484</span> | [Find Permutation](https://leetcode.com/problems/find-permutation "寻找排列") 🔒 | [Go](../problems/find-permutation) | Medium |
-| <span id="485">485</span> | [Max Consecutive Ones](https://leetcode.com/problems/max-consecutive-ones "最大连续 1 的个数") | [Go](../problems/max-consecutive-ones) | Easy |
-| <span id="486">486</span> | [Predict the Winner](https://leetcode.com/problems/predict-the-winner "预测赢家") | [Go](../problems/predict-the-winner) | Medium |
-| <span id="487">487</span> | [Max Consecutive Ones II](https://leetcode.com/problems/max-consecutive-ones-ii "最大连续1的个数 II") 🔒 | [Go](../problems/max-consecutive-ones-ii) | Medium |
-| <span id="488">488</span> | [Zuma Game](https://leetcode.com/problems/zuma-game "祖玛游戏") | [Go](../problems/zuma-game) | Hard |
-| <span id="489">489</span> | [Robot Room Cleaner](https://leetcode.com/problems/robot-room-cleaner "扫地机器人") 🔒 | [Go](../problems/robot-room-cleaner) | Hard |
-| <span id="490">490</span> | [The Maze](https://leetcode.com/problems/the-maze "迷宫") 🔒 | [Go](../problems/the-maze) | Medium |
-| <span id="491">491</span> | [Increasing Subsequences](https://leetcode.com/problems/increasing-subsequences "递增子序列") | [Go](../problems/increasing-subsequences) | Medium |
-| <span id="492">492</span> | [Construct the Rectangle](https://leetcode.com/problems/construct-the-rectangle "构造矩形") | [Go](../problems/construct-the-rectangle) | Easy |
-| <span id="493">493</span> | [Reverse Pairs](https://leetcode.com/problems/reverse-pairs "翻转对") | [Go](../problems/reverse-pairs) | Hard |
-| <span id="494">494</span> | [Target Sum](https://leetcode.com/problems/target-sum "目标和") | [Go](../problems/target-sum) | Medium |
-| <span id="495">495</span> | [Teemo Attacking](https://leetcode.com/problems/teemo-attacking "提莫攻击") | [Go](../problems/teemo-attacking) | Easy |
-| <span id="496">496</span> | [Next Greater Element I](https://leetcode.com/problems/next-greater-element-i "下一个更大元素 I") | [Go](../problems/next-greater-element-i) | Easy |
-| <span id="497">497</span> | [Random Point in Non-overlapping Rectangles](https://leetcode.com/problems/random-point-in-non-overlapping-rectangles "非重叠矩形中的随机点") | [Go](../problems/random-point-in-non-overlapping-rectangles) | Medium |
-| <span id="498">498</span> | [Diagonal Traverse](https://leetcode.com/problems/diagonal-traverse "对角线遍历") | [Go](../problems/diagonal-traverse) | Medium |
-| <span id="499">499</span> | [The Maze III](https://leetcode.com/problems/the-maze-iii "迷宫 III") 🔒 | [Go](../problems/the-maze-iii) | Hard |
-| <span id="500">500</span> | [Keyboard Row](https://leetcode.com/problems/keyboard-row "键盘行") | [Go](../problems/keyboard-row) | Easy |
-| <span id="501">501</span> | [Find Mode in Binary Search Tree](https://leetcode.com/problems/find-mode-in-binary-search-tree "二叉搜索树中的众数") | [Go](../problems/find-mode-in-binary-search-tree) | Easy |
-| <span id="502">502</span> | [IPO](https://leetcode.com/problems/ipo "IPO") | [Go](../problems/ipo) | Hard |
-| <span id="503">503</span> | [Next Greater Element II](https://leetcode.com/problems/next-greater-element-ii "下一个更大元素 II") | [Go](../problems/next-greater-element-ii) | Medium |
-| <span id="504">504</span> | [Base 7](https://leetcode.com/problems/base-7 "七进制数") | [Go](../problems/base-7) | Easy |
-| <span id="505">505</span> | [The Maze II](https://leetcode.com/problems/the-maze-ii "迷宫 II") 🔒 | [Go](../problems/the-maze-ii) | Medium |
-| <span id="506">506</span> | [Relative Ranks](https://leetcode.com/problems/relative-ranks "相对名次") | [Go](../problems/relative-ranks) | Easy |
-| <span id="507">507</span> | [Perfect Number](https://leetcode.com/problems/perfect-number "完美数") | [Go](../problems/perfect-number) | Easy |
-| <span id="508">508</span> | [Most Frequent Subtree Sum](https://leetcode.com/problems/most-frequent-subtree-sum "出现次数最多的子树元素和") | [Go](../problems/most-frequent-subtree-sum) | Medium |
-| <span id="509">509</span> | [Fibonacci Number](https://leetcode.com/problems/fibonacci-number "斐波那契数") | [Go](../problems/fibonacci-number) | Easy |
-| <span id="510">510</span> | [Inorder Successor in BST II](https://leetcode.com/problems/inorder-successor-in-bst-ii "二叉搜索树中的中序后继 II") 🔒 | [Go](../problems/inorder-successor-in-bst-ii) | Medium |
-| <span id="511">511</span> | [Game Play Analysis I](https://leetcode.com/problems/game-play-analysis-i "游戏玩法分析 I") 🔒 | [MySQL](../problems/game-play-analysis-i) | Easy |
-| <span id="512">512</span> | [Game Play Analysis II](https://leetcode.com/problems/game-play-analysis-ii "游戏玩法分析 II") 🔒 | [MySQL](../problems/game-play-analysis-ii) | Easy |
-| <span id="513">513</span> | [Find Bottom Left Tree Value](https://leetcode.com/problems/find-bottom-left-tree-value "找树左下角的值") | [Go](../problems/find-bottom-left-tree-value) | Medium |
-| <span id="514">514</span> | [Freedom Trail](https://leetcode.com/problems/freedom-trail "自由之路") | [Go](../problems/freedom-trail) | Hard |
-| <span id="515">515</span> | [Find Largest Value in Each Tree Row](https://leetcode.com/problems/find-largest-value-in-each-tree-row "在每个树行中找最大值") | [Go](../problems/find-largest-value-in-each-tree-row) | Medium |
-| <span id="516">516</span> | [Longest Palindromic Subsequence](https://leetcode.com/problems/longest-palindromic-subsequence "最长回文子序列") | [Go](../problems/longest-palindromic-subsequence) | Medium |
-| <span id="517">517</span> | [Super Washing Machines](https://leetcode.com/problems/super-washing-machines "超级洗衣机") | [Go](../problems/super-washing-machines) | Hard |
-| <span id="518">518</span> | [Coin Change 2](https://leetcode.com/problems/coin-change-2 "零钱兑换 II") | [Go](../problems/coin-change-2) | Medium |
-| <span id="519">519</span> | [Random Flip Matrix](https://leetcode.com/problems/random-flip-matrix "随机翻转矩阵") | [Go](../problems/random-flip-matrix) | Medium |
-| <span id="520">520</span> | [Detect Capital](https://leetcode.com/problems/detect-capital "检测大写字母") | [Go](../problems/detect-capital) | Easy |
-| <span id="521">521</span> | [Longest Uncommon Subsequence I](https://leetcode.com/problems/longest-uncommon-subsequence-i "最长特殊序列 Ⅰ") | [Go](../problems/longest-uncommon-subsequence-i) | Easy |
-| <span id="522">522</span> | [Longest Uncommon Subsequence II](https://leetcode.com/problems/longest-uncommon-subsequence-ii "最长特殊序列 II") | [Go](../problems/longest-uncommon-subsequence-ii) | Medium |
-| <span id="523">523</span> | [Continuous Subarray Sum](https://leetcode.com/problems/continuous-subarray-sum "连续的子数组和") | [Go](../problems/continuous-subarray-sum) | Medium |
-| <span id="524">524</span> | [Longest Word in Dictionary through Deleting](https://leetcode.com/problems/longest-word-in-dictionary-through-deleting "通过删除字母匹配到字典里最长单词") | [Go](../problems/longest-word-in-dictionary-through-deleting) | Medium |
-| <span id="525">525</span> | [Contiguous Array](https://leetcode.com/problems/contiguous-array "连续数组") | [Go](../problems/contiguous-array) | Medium |
-| <span id="526">526</span> | [Beautiful Arrangement](https://leetcode.com/problems/beautiful-arrangement "优美的排列") | [Go](../problems/beautiful-arrangement) | Medium |
-| <span id="527">527</span> | [Word Abbreviation](https://leetcode.com/problems/word-abbreviation "单词缩写") 🔒 | [Go](../problems/word-abbreviation) | Hard |
-| <span id="528">528</span> | [Random Pick with Weight](https://leetcode.com/problems/random-pick-with-weight "按权重随机选择") | [Go](../problems/random-pick-with-weight) | Medium |
-| <span id="529">529</span> | [Minesweeper](https://leetcode.com/problems/minesweeper "扫雷游戏") | [Go](../problems/minesweeper) | Medium |
-| <span id="530">530</span> | [Minimum Absolute Difference in BST](https://leetcode.com/problems/minimum-absolute-difference-in-bst "二叉搜索树的最小绝对差") | [Go](../problems/minimum-absolute-difference-in-bst) | Easy |
-| <span id="531">531</span> | [Lonely Pixel I](https://leetcode.com/problems/lonely-pixel-i "孤独像素 I") 🔒 | [Go](../problems/lonely-pixel-i) | Medium |
-| <span id="532">532</span> | [K-diff Pairs in an Array](https://leetcode.com/problems/k-diff-pairs-in-an-array "数组中的 k-diff 数对") | [Go](../problems/k-diff-pairs-in-an-array) | Medium |
-| <span id="533">533</span> | [Lonely Pixel II](https://leetcode.com/problems/lonely-pixel-ii "孤独像素 II") 🔒 | [Go](../problems/lonely-pixel-ii) | Medium |
-| <span id="534">534</span> | [Game Play Analysis III](https://leetcode.com/problems/game-play-analysis-iii "游戏玩法分析 III") 🔒 | [MySQL](../problems/game-play-analysis-iii) | Medium |
-| <span id="535">535</span> | [Encode and Decode TinyURL](https://leetcode.com/problems/encode-and-decode-tinyurl "TinyURL 的加密与解密") | [Go](../problems/encode-and-decode-tinyurl) | Medium |
-| <span id="536">536</span> | [Construct Binary Tree from String](https://leetcode.com/problems/construct-binary-tree-from-string "从字符串生成二叉树") 🔒 | [Go](../problems/construct-binary-tree-from-string) | Medium |
-| <span id="537">537</span> | [Complex Number Multiplication](https://leetcode.com/problems/complex-number-multiplication "复数乘法") | [Go](../problems/complex-number-multiplication) | Medium |
-| <span id="538">538</span> | [Convert BST to Greater Tree](https://leetcode.com/problems/convert-bst-to-greater-tree "把二叉搜索树转换为累加树") | [Go](../problems/convert-bst-to-greater-tree) | Medium |
-| <span id="539">539</span> | [Minimum Time Difference](https://leetcode.com/problems/minimum-time-difference "最小时间差") | [Go](../problems/minimum-time-difference) | Medium |
-| <span id="540">540</span> | [Single Element in a Sorted Array](https://leetcode.com/problems/single-element-in-a-sorted-array "有序数组中的单一元素") | [Go](../problems/single-element-in-a-sorted-array) | Medium |
-| <span id="541">541</span> | [Reverse String II](https://leetcode.com/problems/reverse-string-ii "反转字符串 II") | [Go](../problems/reverse-string-ii) | Easy |
-| <span id="542">542</span> | [01 Matrix](https://leetcode.com/problems/01-matrix "01 矩阵") | [Go](../problems/01-matrix) | Medium |
-| <span id="543">543</span> | [Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree "二叉树的直径") | [Go](../problems/diameter-of-binary-tree) | Easy |
-| <span id="544">544</span> | [Output Contest Matches](https://leetcode.com/problems/output-contest-matches "输出比赛匹配对") 🔒 | [Go](../problems/output-contest-matches) | Medium |
-| <span id="545">545</span> | [Boundary of Binary Tree](https://leetcode.com/problems/boundary-of-binary-tree "二叉树的边界") 🔒 | [Go](../problems/boundary-of-binary-tree) | Medium |
-| <span id="546">546</span> | [Remove Boxes](https://leetcode.com/problems/remove-boxes "移除盒子") | [Go](../problems/remove-boxes) | Hard |
-| <span id="547">547</span> | [Number of Provinces](https://leetcode.com/problems/number-of-provinces "省份数量") | [Go](../problems/number-of-provinces) | Medium |
-| <span id="548">548</span> | [Split Array with Equal Sum](https://leetcode.com/problems/split-array-with-equal-sum "将数组分割成和相等的子数组") 🔒 | [Go](../problems/split-array-with-equal-sum) | Hard |
-| <span id="549">549</span> | [Binary Tree Longest Consecutive Sequence II](https://leetcode.com/problems/binary-tree-longest-consecutive-sequence-ii "二叉树中最长的连续序列") 🔒 | [Go](../problems/binary-tree-longest-consecutive-sequence-ii) | Medium |
-| <span id="550">550</span> | [Game Play Analysis IV](https://leetcode.com/problems/game-play-analysis-iv "游戏玩法分析 IV") 🔒 | [MySQL](../problems/game-play-analysis-iv) | Medium |
-| <span id="551">551</span> | [Student Attendance Record I](https://leetcode.com/problems/student-attendance-record-i "学生出勤记录 I") | [Go](../problems/student-attendance-record-i) | Easy |
-| <span id="552">552</span> | [Student Attendance Record II](https://leetcode.com/problems/student-attendance-record-ii "学生出勤记录 II") | [Go](../problems/student-attendance-record-ii) | Hard |
-| <span id="553">553</span> | [Optimal Division](https://leetcode.com/problems/optimal-division "最优除法") | [Go](../problems/optimal-division) | Medium |
-| <span id="554">554</span> | [Brick Wall](https://leetcode.com/problems/brick-wall "砖墙") | [Go](../problems/brick-wall) | Medium |
-| <span id="555">555</span> | [Split Concatenated Strings](https://leetcode.com/problems/split-concatenated-strings "分割连接字符串") 🔒 | [Go](../problems/split-concatenated-strings) | Medium |
-| <span id="556">556</span> | [Next Greater Element III](https://leetcode.com/problems/next-greater-element-iii "下一个更大元素 III") | [Go](../problems/next-greater-element-iii) | Medium |
-| <span id="557">557</span> | [Reverse Words in a String III](https://leetcode.com/problems/reverse-words-in-a-string-iii "反转字符串中的单词 III") | [Go](../problems/reverse-words-in-a-string-iii) | Easy |
-| <span id="558">558</span> | [Logical OR of Two Binary Grids Represented as Quad-Trees](https://leetcode.com/problems/logical-or-of-two-binary-grids-represented-as-quad-trees "四叉树交集") | [Go](../problems/logical-or-of-two-binary-grids-represented-as-quad-trees) | Medium |
-| <span id="559">559</span> | [Maximum Depth of N-ary Tree](https://leetcode.com/problems/maximum-depth-of-n-ary-tree "N 叉树的最大深度") | [Go](../problems/maximum-depth-of-n-ary-tree) | Easy |
-| <span id="560">560</span> | [Subarray Sum Equals K](https://leetcode.com/problems/subarray-sum-equals-k "和为 K 的子数组") | [Go](../problems/subarray-sum-equals-k) | Medium |
-| <span id="561">561</span> | [Array Partition I](https://leetcode.com/problems/array-partition-i "数组拆分 I") | [Go](../problems/array-partition-i) | Easy |
-| <span id="562">562</span> | [Longest Line of Consecutive One in Matrix](https://leetcode.com/problems/longest-line-of-consecutive-one-in-matrix "矩阵中最长的连续1线段") 🔒 | [Go](../problems/longest-line-of-consecutive-one-in-matrix) | Medium |
-| <span id="563">563</span> | [Binary Tree Tilt](https://leetcode.com/problems/binary-tree-tilt "二叉树的坡度") | [Go](../problems/binary-tree-tilt) | Easy |
-| <span id="564">564</span> | [Find the Closest Palindrome](https://leetcode.com/problems/find-the-closest-palindrome "寻找最近的回文数") | [Go](../problems/find-the-closest-palindrome) | Hard |
-| <span id="565">565</span> | [Array Nesting](https://leetcode.com/problems/array-nesting "数组嵌套") | [Go](../problems/array-nesting) | Medium |
-| <span id="566">566</span> | [Reshape the Matrix](https://leetcode.com/problems/reshape-the-matrix "重塑矩阵") | [Go](../problems/reshape-the-matrix) | Easy |
-| <span id="567">567</span> | [Permutation in String](https://leetcode.com/problems/permutation-in-string "字符串的排列") | [Go](../problems/permutation-in-string) | Medium |
-| <span id="568">568</span> | [Maximum Vacation Days](https://leetcode.com/problems/maximum-vacation-days "最大休假天数") 🔒 | [Go](../problems/maximum-vacation-days) | Hard |
-| <span id="569">569</span> | [Median Employee Salary](https://leetcode.com/problems/median-employee-salary "员工薪水中位数") 🔒 | [MySQL](../problems/median-employee-salary) | Hard |
-| <span id="570">570</span> | [Managers with at Least 5 Direct Reports](https://leetcode.com/problems/managers-with-at-least-5-direct-reports "至少有5名直接下属的经理") 🔒 | [MySQL](../problems/managers-with-at-least-5-direct-reports) | Medium |
-| <span id="571">571</span> | [Find Median Given Frequency of Numbers](https://leetcode.com/problems/find-median-given-frequency-of-numbers "给定数字的频率查询中位数") 🔒 | [MySQL](../problems/find-median-given-frequency-of-numbers) | Hard |
-| <span id="572">572</span> | [Subtree of Another Tree](https://leetcode.com/problems/subtree-of-another-tree "另一棵树的子树") | [Go](../problems/subtree-of-another-tree) | Easy |
-| <span id="573">573</span> | [Squirrel Simulation](https://leetcode.com/problems/squirrel-simulation "松鼠模拟") 🔒 | [Go](../problems/squirrel-simulation) | Medium |
-| <span id="574">574</span> | [Winning Candidate](https://leetcode.com/problems/winning-candidate "当选者") 🔒 | [MySQL](../problems/winning-candidate) | Medium |
-| <span id="575">575</span> | [Distribute Candies](https://leetcode.com/problems/distribute-candies "分糖果") | [Go](../problems/distribute-candies) | Easy |
-| <span id="576">576</span> | [Out of Boundary Paths](https://leetcode.com/problems/out-of-boundary-paths "出界的路径数") | [Go](../problems/out-of-boundary-paths) | Medium |
-| <span id="577">577</span> | [Employee Bonus](https://leetcode.com/problems/employee-bonus "员工奖金") 🔒 | [MySQL](../problems/employee-bonus) | Easy |
-| <span id="578">578</span> | [Get Highest Answer Rate Question](https://leetcode.com/problems/get-highest-answer-rate-question "查询回答率最高的问题") 🔒 | [MySQL](../problems/get-highest-answer-rate-question) | Medium |
-| <span id="579">579</span> | [Find Cumulative Salary of an Employee](https://leetcode.com/problems/find-cumulative-salary-of-an-employee "查询员工的累计薪水") 🔒 | [MySQL](../problems/find-cumulative-salary-of-an-employee) | Hard |
-| <span id="580">580</span> | [Count Student Number in Departments](https://leetcode.com/problems/count-student-number-in-departments "统计各专业学生人数") 🔒 | [MySQL](../problems/count-student-number-in-departments) | Medium |
-| <span id="581">581</span> | [Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/shortest-unsorted-continuous-subarray "最短无序连续子数组") | [Go](../problems/shortest-unsorted-continuous-subarray) | Medium |
-| <span id="582">582</span> | [Kill Process](https://leetcode.com/problems/kill-process "杀掉进程") 🔒 | [Go](../problems/kill-process) | Medium |
-| <span id="583">583</span> | [Delete Operation for Two Strings](https://leetcode.com/problems/delete-operation-for-two-strings "两个字符串的删除操作") | [Go](../problems/delete-operation-for-two-strings) | Medium |
-| <span id="584">584</span> | [Find Customer Referee](https://leetcode.com/problems/find-customer-referee "寻找用户推荐人") 🔒 | [MySQL](../problems/find-customer-referee) | Easy |
-| <span id="585">585</span> | [Investments in 2016](https://leetcode.com/problems/investments-in-2016 "2016年的投资") 🔒 | [MySQL](../problems/investments-in-2016) | Medium |
-| <span id="586">586</span> | [Customer Placing the Largest Number of Orders](https://leetcode.com/problems/customer-placing-the-largest-number-of-orders "订单最多的客户") 🔒 | [MySQL](../problems/customer-placing-the-largest-number-of-orders) | Easy |
-| <span id="587">587</span> | [Erect the Fence](https://leetcode.com/problems/erect-the-fence "安装栅栏") | [Go](../problems/erect-the-fence) | Hard |
-| <span id="588">588</span> | [Design In-Memory File System](https://leetcode.com/problems/design-in-memory-file-system "设计内存文件系统") 🔒 | [Go](../problems/design-in-memory-file-system) | Hard |
-| <span id="589">589</span> | [N-ary Tree Preorder Traversal](https://leetcode.com/problems/n-ary-tree-preorder-traversal "N 叉树的前序遍历") | [Go](../problems/n-ary-tree-preorder-traversal) | Easy |
-| <span id="590">590</span> | [N-ary Tree Postorder Traversal](https://leetcode.com/problems/n-ary-tree-postorder-traversal "N 叉树的后序遍历") | [Go](../problems/n-ary-tree-postorder-traversal) | Easy |
-| <span id="591">591</span> | [Tag Validator](https://leetcode.com/problems/tag-validator "标签验证器") | [Go](../problems/tag-validator) | Hard |
-| <span id="592">592</span> | [Fraction Addition and Subtraction](https://leetcode.com/problems/fraction-addition-and-subtraction "分数加减运算") | [Go](../problems/fraction-addition-and-subtraction) | Medium |
-| <span id="593">593</span> | [Valid Square](https://leetcode.com/problems/valid-square "有效的正方形") | [Go](../problems/valid-square) | Medium |
-| <span id="594">594</span> | [Longest Harmonious Subsequence](https://leetcode.com/problems/longest-harmonious-subsequence "最长和谐子序列") | [Go](../problems/longest-harmonious-subsequence) | Easy |
-| <span id="595">595</span> | [Big Countries](https://leetcode.com/problems/big-countries "大的国家") | [MySQL](../problems/big-countries) | Easy |
-| <span id="596">596</span> | [Classes More Than 5 Students](https://leetcode.com/problems/classes-more-than-5-students "超过5名学生的课") | [MySQL](../problems/classes-more-than-5-students) | Easy |
-| <span id="597">597</span> | [Friend Requests I: Overall Acceptance Rate](https://leetcode.com/problems/friend-requests-i-overall-acceptance-rate "好友申请 I：总体通过率") 🔒 | [MySQL](../problems/friend-requests-i-overall-acceptance-rate) | Easy |
-| <span id="598">598</span> | [Range Addition II](https://leetcode.com/problems/range-addition-ii "范围求和 II") | [Go](../problems/range-addition-ii) | Easy |
-| <span id="599">599</span> | [Minimum Index Sum of Two Lists](https://leetcode.com/problems/minimum-index-sum-of-two-lists "两个列表的最小索引总和") | [Go](../problems/minimum-index-sum-of-two-lists) | Easy |
-| <span id="600">600</span> | [Non-negative Integers without Consecutive Ones](https://leetcode.com/problems/non-negative-integers-without-consecutive-ones "不含连续1的非负整数") | [Go](../problems/non-negative-integers-without-consecutive-ones) | Hard |
diff --git a/readme/601-900.md b/readme/601-900.md
deleted file mode 100644
index 91d593fbe..000000000
--- a/readme/601-900.md
+++ /dev/null
@@ -1,388 +0,0 @@
-<!--|This file generated by command(leetcode readme); DO NOT EDIT.         |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-# [LeetCode](https://awesee.github.io/leetcode)
-LeetCode Problems' Solutions
-[[力扣](https://awesee.github.io/categories/leetcode/) ∙ [话题分类](https://github.com/awesee/leetcode/blob/master/tag/README.md)]
-
-[![Go](https://github.com/awesee/leetcode/workflows/Go/badge.svg)](https://github.com/awesee/leetcode/actions)
-[![codecov](https://codecov.io/gh/awesee/leetcode/branch/master/graph/badge.svg)](https://codecov.io/gh/awesee/leetcode)
-[![Go Report Card](https://goreportcard.com/badge/github.com/awesee/leetcode)](https://goreportcard.com/report/github.com/awesee/leetcode)
-[![GitHub contributors](https://img.shields.io/github/contributors/awesee/leetcode.svg)](https://github.com/awesee/leetcode/graphs/contributors)
-[![license](https://img.shields.io/github/license/awesee/leetcode.svg)](https://github.com/awesee/leetcode/blob/master/LICENSE)
-[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fawesee%2Fleetcode.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fawesee%2Fleetcode?ref=badge_shield)
-[![Join the chat](https://badges.gitter.im/awesee/leetcode.svg)](https://gitter.im/awesee/leetcode?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-
-<table><thead>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#1">[1-50]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#51">[51-100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#101">[101-150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#151">[151-200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#201">[201-250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#251">[251-300]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#301">[301-350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#351">[351-400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#401">[401-450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#451">[451-500]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#501">[501-550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#551">[551-600]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#601">[601-650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#651">[651-700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#701">[701-750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#751">[751-800]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#801">[801-850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#851">[851-900]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#901">[901-950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#951">[951-1000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1001">[1001-1050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1051">[1051-1100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1101">[1101-1150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1151">[1151-1200]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1201">[1201-1250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1251">[1251-1300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1301">[1301-1350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1351">[1351-1400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1401">[1401-1450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1451">[1451-1500]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1501">[1501-1550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1551">[1551-1600]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1601">[1601-1650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1651">[1651-1700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1701">[1701-1750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1751">[1751-1800]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1850">[1801-1850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1900">[1851-1900]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1950">[1901-1950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2000">[1951-2000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2050">[2001-2050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2100">[2051-2100]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2150">[2101-2150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2200">[2151-2200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2250">[2201-2250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2300">[2251-2300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2350">[2301-2350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2400">[2351-2400]</a></th>
-</tr>
-</thead></table>
-
-| # | Title | Solution | Difficulty |
-| :-: | - | - | :-: |
-| <span id="601">601</span> | [Human Traffic of Stadium](https://leetcode.com/problems/human-traffic-of-stadium "体育馆的人流量") | [MySQL](../problems/human-traffic-of-stadium) | Hard |
-| <span id="602">602</span> | [Friend Requests II: Who Has the Most Friends](https://leetcode.com/problems/friend-requests-ii-who-has-the-most-friends "好友申请 II ：谁有最多的好友") 🔒 | [MySQL](../problems/friend-requests-ii-who-has-the-most-friends) | Medium |
-| <span id="603">603</span> | [Consecutive Available Seats](https://leetcode.com/problems/consecutive-available-seats "连续空余座位") 🔒 | [MySQL](../problems/consecutive-available-seats) | Easy |
-| <span id="604">604</span> | [Design Compressed String Iterator](https://leetcode.com/problems/design-compressed-string-iterator "迭代压缩字符串") 🔒 | [Go](../problems/design-compressed-string-iterator) | Easy |
-| <span id="605">605</span> | [Can Place Flowers](https://leetcode.com/problems/can-place-flowers "种花问题") | [Go](../problems/can-place-flowers) | Easy |
-| <span id="606">606</span> | [Construct String from Binary Tree](https://leetcode.com/problems/construct-string-from-binary-tree "根据二叉树创建字符串") | [Go](../problems/construct-string-from-binary-tree) | Easy |
-| <span id="607">607</span> | [Sales Person](https://leetcode.com/problems/sales-person "销售员") 🔒 | [MySQL](../problems/sales-person) | Easy |
-| <span id="608">608</span> | [Tree Node](https://leetcode.com/problems/tree-node "树节点") 🔒 | [MySQL](../problems/tree-node) | Medium |
-| <span id="609">609</span> | [Find Duplicate File in System](https://leetcode.com/problems/find-duplicate-file-in-system "在系统中查找重复文件") | [Go](../problems/find-duplicate-file-in-system) | Medium |
-| <span id="610">610</span> | [Triangle Judgement](https://leetcode.com/problems/triangle-judgement "判断三角形") 🔒 | [MySQL](../problems/triangle-judgement) | Easy |
-| <span id="611">611</span> | [Valid Triangle Number](https://leetcode.com/problems/valid-triangle-number "有效三角形的个数") | [Go](../problems/valid-triangle-number) | Medium |
-| <span id="612">612</span> | [Shortest Distance in a Plane](https://leetcode.com/problems/shortest-distance-in-a-plane "平面上的最近距离") 🔒 | [MySQL](../problems/shortest-distance-in-a-plane) | Medium |
-| <span id="613">613</span> | [Shortest Distance in a Line](https://leetcode.com/problems/shortest-distance-in-a-line "直线上的最近距离") 🔒 | [MySQL](../problems/shortest-distance-in-a-line) | Easy |
-| <span id="614">614</span> | [Second Degree Follower](https://leetcode.com/problems/second-degree-follower "二级关注者") 🔒 | [MySQL](../problems/second-degree-follower) | Medium |
-| <span id="615">615</span> | [Average Salary: Departments VS Company](https://leetcode.com/problems/average-salary-departments-vs-company "平均工资：部门与公司比较") 🔒 | [MySQL](../problems/average-salary-departments-vs-company) | Hard |
-| <span id="616">616</span> | [Add Bold Tag in String](https://leetcode.com/problems/add-bold-tag-in-string "给字符串添加加粗标签") 🔒 | [Go](../problems/add-bold-tag-in-string) | Medium |
-| <span id="617">617</span> | [Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees "合并二叉树") | [Go](../problems/merge-two-binary-trees) | Easy |
-| <span id="618">618</span> | [Students Report By Geography](https://leetcode.com/problems/students-report-by-geography "学生地理信息报告") 🔒 | [MySQL](../problems/students-report-by-geography) | Hard |
-| <span id="619">619</span> | [Biggest Single Number](https://leetcode.com/problems/biggest-single-number "只出现一次的最大数字") 🔒 | [MySQL](../problems/biggest-single-number) | Easy |
-| <span id="620">620</span> | [Not Boring Movies](https://leetcode.com/problems/not-boring-movies "有趣的电影") | [MySQL](../problems/not-boring-movies) | Easy |
-| <span id="621">621</span> | [Task Scheduler](https://leetcode.com/problems/task-scheduler "任务调度器") | [Go](../problems/task-scheduler) | Medium |
-| <span id="622">622</span> | [Design Circular Queue](https://leetcode.com/problems/design-circular-queue "设计循环队列") | [Go](../problems/design-circular-queue) | Medium |
-| <span id="623">623</span> | [Add One Row to Tree](https://leetcode.com/problems/add-one-row-to-tree "在二叉树中增加一行") | [Go](../problems/add-one-row-to-tree) | Medium |
-| <span id="624">624</span> | [Maximum Distance in Arrays](https://leetcode.com/problems/maximum-distance-in-arrays "数组列表中的最大距离") 🔒 | [Go](../problems/maximum-distance-in-arrays) | Medium |
-| <span id="625">625</span> | [Minimum Factorization](https://leetcode.com/problems/minimum-factorization "最小因式分解") 🔒 | [Go](../problems/minimum-factorization) | Medium |
-| <span id="626">626</span> | [Exchange Seats](https://leetcode.com/problems/exchange-seats "换座位") | [MySQL](../problems/exchange-seats) | Medium |
-| <span id="627">627</span> | [Swap Salary](https://leetcode.com/problems/swap-salary "变更性别") | [MySQL](../problems/swap-salary) | Easy |
-| <span id="628">628</span> | [Maximum Product of Three Numbers](https://leetcode.com/problems/maximum-product-of-three-numbers "三个数的最大乘积") | [Go](../problems/maximum-product-of-three-numbers) | Easy |
-| <span id="629">629</span> | [K Inverse Pairs Array](https://leetcode.com/problems/k-inverse-pairs-array "K个逆序对数组") | [Go](../problems/k-inverse-pairs-array) | Hard |
-| <span id="630">630</span> | [Course Schedule III](https://leetcode.com/problems/course-schedule-iii "课程表 III") | [Go](../problems/course-schedule-iii) | Hard |
-| <span id="631">631</span> | [Design Excel Sum Formula](https://leetcode.com/problems/design-excel-sum-formula "设计 Excel 求和公式") 🔒 | [Go](../problems/design-excel-sum-formula) | Hard |
-| <span id="632">632</span> | [Smallest Range Covering Elements from K Lists](https://leetcode.com/problems/smallest-range-covering-elements-from-k-lists "最小区间") | [Go](../problems/smallest-range-covering-elements-from-k-lists) | Hard |
-| <span id="633">633</span> | [Sum of Square Numbers](https://leetcode.com/problems/sum-of-square-numbers "平方数之和") | [Go](../problems/sum-of-square-numbers) | Medium |
-| <span id="634">634</span> | [Find the Derangement of An Array](https://leetcode.com/problems/find-the-derangement-of-an-array "寻找数组的错位排列") 🔒 | [Go](../problems/find-the-derangement-of-an-array) | Medium |
-| <span id="635">635</span> | [Design Log Storage System](https://leetcode.com/problems/design-log-storage-system "设计日志存储系统") 🔒 | [Go](../problems/design-log-storage-system) | Medium |
-| <span id="636">636</span> | [Exclusive Time of Functions](https://leetcode.com/problems/exclusive-time-of-functions "函数的独占时间") | [Go](../problems/exclusive-time-of-functions) | Medium |
-| <span id="637">637</span> | [Average of Levels in Binary Tree](https://leetcode.com/problems/average-of-levels-in-binary-tree "二叉树的层平均值") | [Go](../problems/average-of-levels-in-binary-tree) | Easy |
-| <span id="638">638</span> | [Shopping Offers](https://leetcode.com/problems/shopping-offers "大礼包") | [Go](../problems/shopping-offers) | Medium |
-| <span id="639">639</span> | [Decode Ways II](https://leetcode.com/problems/decode-ways-ii "解码方法 II") | [Go](../problems/decode-ways-ii) | Hard |
-| <span id="640">640</span> | [Solve the Equation](https://leetcode.com/problems/solve-the-equation "求解方程") | [Go](../problems/solve-the-equation) | Medium |
-| <span id="641">641</span> | [Design Circular Deque](https://leetcode.com/problems/design-circular-deque "设计循环双端队列") | [Go](../problems/design-circular-deque) | Medium |
-| <span id="642">642</span> | [Design Search Autocomplete System](https://leetcode.com/problems/design-search-autocomplete-system "设计搜索自动补全系统") 🔒 | [Go](../problems/design-search-autocomplete-system) | Hard |
-| <span id="643">643</span> | [Maximum Average Subarray I](https://leetcode.com/problems/maximum-average-subarray-i "子数组最大平均数 I") | [Go](../problems/maximum-average-subarray-i) | Easy |
-| <span id="644">644</span> | [Maximum Average Subarray II](https://leetcode.com/problems/maximum-average-subarray-ii "子数组最大平均数 II") 🔒 | [Go](../problems/maximum-average-subarray-ii) | Hard |
-| <span id="645">645</span> | [Set Mismatch](https://leetcode.com/problems/set-mismatch "错误的集合") | [Go](../problems/set-mismatch) | Easy |
-| <span id="646">646</span> | [Maximum Length of Pair Chain](https://leetcode.com/problems/maximum-length-of-pair-chain "最长数对链") | [Go](../problems/maximum-length-of-pair-chain) | Medium |
-| <span id="647">647</span> | [Palindromic Substrings](https://leetcode.com/problems/palindromic-substrings "回文子串") | [Go](../problems/palindromic-substrings) | Medium |
-| <span id="648">648</span> | [Replace Words](https://leetcode.com/problems/replace-words "单词替换") | [Go](../problems/replace-words) | Medium |
-| <span id="649">649</span> | [Dota2 Senate](https://leetcode.com/problems/dota2-senate "Dota2 参议院") | [Go](../problems/dota2-senate) | Medium |
-| <span id="650">650</span> | [2 Keys Keyboard](https://leetcode.com/problems/2-keys-keyboard "只有两个键的键盘") | [Go](../problems/2-keys-keyboard) | Medium |
-| <span id="651">651</span> | [4 Keys Keyboard](https://leetcode.com/problems/4-keys-keyboard "4键键盘") 🔒 | [Go](../problems/4-keys-keyboard) | Medium |
-| <span id="652">652</span> | [Find Duplicate Subtrees](https://leetcode.com/problems/find-duplicate-subtrees "寻找重复的子树") | [Go](../problems/find-duplicate-subtrees) | Medium |
-| <span id="653">653</span> | [Two Sum IV - Input is a BST](https://leetcode.com/problems/two-sum-iv-input-is-a-bst "两数之和 IV - 输入 BST") | [Go](../problems/two-sum-iv-input-is-a-bst) | Easy |
-| <span id="654">654</span> | [Maximum Binary Tree](https://leetcode.com/problems/maximum-binary-tree "最大二叉树") | [Go](../problems/maximum-binary-tree) | Medium |
-| <span id="655">655</span> | [Print Binary Tree](https://leetcode.com/problems/print-binary-tree "输出二叉树") | [Go](../problems/print-binary-tree) | Medium |
-| <span id="656">656</span> | [Coin Path](https://leetcode.com/problems/coin-path "金币路径") 🔒 | [Go](../problems/coin-path) | Hard |
-| <span id="657">657</span> | [Robot Return to Origin](https://leetcode.com/problems/robot-return-to-origin "机器人能否返回原点") | [Go](../problems/robot-return-to-origin) | Easy |
-| <span id="658">658</span> | [Find K Closest Elements](https://leetcode.com/problems/find-k-closest-elements "找到 K 个最接近的元素") | [Go](../problems/find-k-closest-elements) | Medium |
-| <span id="659">659</span> | [Split Array into Consecutive Subsequences](https://leetcode.com/problems/split-array-into-consecutive-subsequences "分割数组为连续子序列") | [Go](../problems/split-array-into-consecutive-subsequences) | Medium |
-| <span id="660">660</span> | [Remove 9](https://leetcode.com/problems/remove-9 "移除 9") 🔒 | [Go](../problems/remove-9) | Hard |
-| <span id="661">661</span> | [Image Smoother](https://leetcode.com/problems/image-smoother "图片平滑器") | [Go](../problems/image-smoother) | Easy |
-| <span id="662">662</span> | [Maximum Width of Binary Tree](https://leetcode.com/problems/maximum-width-of-binary-tree "二叉树最大宽度") | [Go](../problems/maximum-width-of-binary-tree) | Medium |
-| <span id="663">663</span> | [Equal Tree Partition](https://leetcode.com/problems/equal-tree-partition "均匀树划分") 🔒 | [Go](../problems/equal-tree-partition) | Medium |
-| <span id="664">664</span> | [Strange Printer](https://leetcode.com/problems/strange-printer "奇怪的打印机") | [Go](../problems/strange-printer) | Hard |
-| <span id="665">665</span> | [Non-decreasing Array](https://leetcode.com/problems/non-decreasing-array "非递减数列") | [Go](../problems/non-decreasing-array) | Medium |
-| <span id="666">666</span> | [Path Sum IV](https://leetcode.com/problems/path-sum-iv "路径总和 IV") 🔒 | [Go](../problems/path-sum-iv) | Medium |
-| <span id="667">667</span> | [Beautiful Arrangement II](https://leetcode.com/problems/beautiful-arrangement-ii "优美的排列 II") | [Go](../problems/beautiful-arrangement-ii) | Medium |
-| <span id="668">668</span> | [Kth Smallest Number in Multiplication Table](https://leetcode.com/problems/kth-smallest-number-in-multiplication-table "乘法表中第k小的数") | [Go](../problems/kth-smallest-number-in-multiplication-table) | Hard |
-| <span id="669">669</span> | [Trim a Binary Search Tree](https://leetcode.com/problems/trim-a-binary-search-tree "修剪二叉搜索树") | [Go](../problems/trim-a-binary-search-tree) | Medium |
-| <span id="670">670</span> | [Maximum Swap](https://leetcode.com/problems/maximum-swap "最大交换") | [Go](../problems/maximum-swap) | Medium |
-| <span id="671">671</span> | [Second Minimum Node In a Binary Tree](https://leetcode.com/problems/second-minimum-node-in-a-binary-tree "二叉树中第二小的节点") | [Go](../problems/second-minimum-node-in-a-binary-tree) | Easy |
-| <span id="672">672</span> | [Bulb Switcher II](https://leetcode.com/problems/bulb-switcher-ii "灯泡开关 Ⅱ") | [Go](../problems/bulb-switcher-ii) | Medium |
-| <span id="673">673</span> | [Number of Longest Increasing Subsequence](https://leetcode.com/problems/number-of-longest-increasing-subsequence "最长递增子序列的个数") | [Go](../problems/number-of-longest-increasing-subsequence) | Medium |
-| <span id="674">674</span> | [Longest Continuous Increasing Subsequence](https://leetcode.com/problems/longest-continuous-increasing-subsequence "最长连续递增序列") | [Go](../problems/longest-continuous-increasing-subsequence) | Easy |
-| <span id="675">675</span> | [Cut Off Trees for Golf Event](https://leetcode.com/problems/cut-off-trees-for-golf-event "为高尔夫比赛砍树") | [Go](../problems/cut-off-trees-for-golf-event) | Hard |
-| <span id="676">676</span> | [Implement Magic Dictionary](https://leetcode.com/problems/implement-magic-dictionary "实现一个魔法字典") | [Go](../problems/implement-magic-dictionary) | Medium |
-| <span id="677">677</span> | [Map Sum Pairs](https://leetcode.com/problems/map-sum-pairs "键值映射") | [Go](../problems/map-sum-pairs) | Medium |
-| <span id="678">678</span> | [Valid Parenthesis String](https://leetcode.com/problems/valid-parenthesis-string "有效的括号字符串") | [Go](../problems/valid-parenthesis-string) | Medium |
-| <span id="679">679</span> | [24 Game](https://leetcode.com/problems/24-game "24 点游戏") | [Go](../problems/24-game) | Hard |
-| <span id="680">680</span> | [Valid Palindrome II](https://leetcode.com/problems/valid-palindrome-ii "验证回文字符串 Ⅱ") | [Go](../problems/valid-palindrome-ii) | Easy |
-| <span id="681">681</span> | [Next Closest Time](https://leetcode.com/problems/next-closest-time "最近时刻") 🔒 | [Go](../problems/next-closest-time) | Medium |
-| <span id="682">682</span> | [Baseball Game](https://leetcode.com/problems/baseball-game "棒球比赛") | [Go](../problems/baseball-game) | Easy |
-| <span id="683">683</span> | [K Empty Slots](https://leetcode.com/problems/k-empty-slots "K 个关闭的灯泡") 🔒 | [Go](../problems/k-empty-slots) | Hard |
-| <span id="684">684</span> | [Redundant Connection](https://leetcode.com/problems/redundant-connection "冗余连接") | [Go](../problems/redundant-connection) | Medium |
-| <span id="685">685</span> | [Redundant Connection II](https://leetcode.com/problems/redundant-connection-ii "冗余连接 II") | [Go](../problems/redundant-connection-ii) | Hard |
-| <span id="686">686</span> | [Repeated String Match](https://leetcode.com/problems/repeated-string-match "重复叠加字符串匹配") | [Go](../problems/repeated-string-match) | Medium |
-| <span id="687">687</span> | [Longest Univalue Path](https://leetcode.com/problems/longest-univalue-path "最长同值路径") | [Go](../problems/longest-univalue-path) | Medium |
-| <span id="688">688</span> | [Knight Probability in Chessboard](https://leetcode.com/problems/knight-probability-in-chessboard "骑士在棋盘上的概率") | [Go](../problems/knight-probability-in-chessboard) | Medium |
-| <span id="689">689</span> | [Maximum Sum of 3 Non-Overlapping Subarrays](https://leetcode.com/problems/maximum-sum-of-3-non-overlapping-subarrays "三个无重叠子数组的最大和") | [Go](../problems/maximum-sum-of-3-non-overlapping-subarrays) | Hard |
-| <span id="690">690</span> | [Employee Importance](https://leetcode.com/problems/employee-importance "员工的重要性") | [Go](../problems/employee-importance) | Medium |
-| <span id="691">691</span> | [Stickers to Spell Word](https://leetcode.com/problems/stickers-to-spell-word "贴纸拼词") | [Go](../problems/stickers-to-spell-word) | Hard |
-| <span id="692">692</span> | [Top K Frequent Words](https://leetcode.com/problems/top-k-frequent-words "前K个高频单词") | [Go](../problems/top-k-frequent-words) | Medium |
-| <span id="693">693</span> | [Binary Number with Alternating Bits](https://leetcode.com/problems/binary-number-with-alternating-bits "交替位二进制数") | [Go](../problems/binary-number-with-alternating-bits) | Easy |
-| <span id="694">694</span> | [Number of Distinct Islands](https://leetcode.com/problems/number-of-distinct-islands "不同岛屿的数量") 🔒 | [Go](../problems/number-of-distinct-islands) | Medium |
-| <span id="695">695</span> | [Max Area of Island](https://leetcode.com/problems/max-area-of-island "岛屿的最大面积") | [Go](../problems/max-area-of-island) | Medium |
-| <span id="696">696</span> | [Count Binary Substrings](https://leetcode.com/problems/count-binary-substrings "计数二进制子串") | [Go](../problems/count-binary-substrings) | Easy |
-| <span id="697">697</span> | [Degree of an Array](https://leetcode.com/problems/degree-of-an-array "数组的度") | [Go](../problems/degree-of-an-array) | Easy |
-| <span id="698">698</span> | [Partition to K Equal Sum Subsets](https://leetcode.com/problems/partition-to-k-equal-sum-subsets "划分为k个相等的子集") | [Go](../problems/partition-to-k-equal-sum-subsets) | Medium |
-| <span id="699">699</span> | [Falling Squares](https://leetcode.com/problems/falling-squares "掉落的方块") | [Go](../problems/falling-squares) | Hard |
-| <span id="700">700</span> | [Search in a Binary Search Tree](https://leetcode.com/problems/search-in-a-binary-search-tree "二叉搜索树中的搜索") | [Go](../problems/search-in-a-binary-search-tree) | Easy |
-| <span id="701">701</span> | [Insert into a Binary Search Tree](https://leetcode.com/problems/insert-into-a-binary-search-tree "二叉搜索树中的插入操作") | [Go](../problems/insert-into-a-binary-search-tree) | Medium |
-| <span id="702">702</span> | [Search in a Sorted Array of Unknown Size](https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size "搜索长度未知的有序数组") 🔒 | [Go](../problems/search-in-a-sorted-array-of-unknown-size) | Medium |
-| <span id="703">703</span> | [Kth Largest Element in a Stream](https://leetcode.com/problems/kth-largest-element-in-a-stream "数据流中的第 K 大元素") | [Go](../problems/kth-largest-element-in-a-stream) | Easy |
-| <span id="704">704</span> | [Binary Search](https://leetcode.com/problems/binary-search "二分查找") | [Go](../problems/binary-search) | Easy |
-| <span id="705">705</span> | [Design HashSet](https://leetcode.com/problems/design-hashset "设计哈希集合") | [Go](../problems/design-hashset) | Easy |
-| <span id="706">706</span> | [Design HashMap](https://leetcode.com/problems/design-hashmap "设计哈希映射") | [Go](../problems/design-hashmap) | Easy |
-| <span id="707">707</span> | [Design Linked List](https://leetcode.com/problems/design-linked-list "设计链表") | [Go](../problems/design-linked-list) | Medium |
-| <span id="708">708</span> | [Insert into a Sorted Circular Linked List](https://leetcode.com/problems/insert-into-a-sorted-circular-linked-list "循环有序列表的插入") 🔒 | [Go](../problems/insert-into-a-sorted-circular-linked-list) | Medium |
-| <span id="709">709</span> | [To Lower Case](https://leetcode.com/problems/to-lower-case "转换成小写字母") | [Go](../problems/to-lower-case) | Easy |
-| <span id="710">710</span> | [Random Pick with Blacklist](https://leetcode.com/problems/random-pick-with-blacklist "黑名单中的随机数") | [Go](../problems/random-pick-with-blacklist) | Hard |
-| <span id="711">711</span> | [Number of Distinct Islands II](https://leetcode.com/problems/number-of-distinct-islands-ii "不同岛屿的数量 II") 🔒 | [Go](../problems/number-of-distinct-islands-ii) | Hard |
-| <span id="712">712</span> | [Minimum ASCII Delete Sum for Two Strings](https://leetcode.com/problems/minimum-ascii-delete-sum-for-two-strings "两个字符串的最小ASCII删除和") | [Go](../problems/minimum-ascii-delete-sum-for-two-strings) | Medium |
-| <span id="713">713</span> | [Subarray Product Less Than K](https://leetcode.com/problems/subarray-product-less-than-k "乘积小于K的子数组") | [Go](../problems/subarray-product-less-than-k) | Medium |
-| <span id="714">714</span> | [Best Time to Buy and Sell Stock with Transaction Fee](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-transaction-fee "买卖股票的最佳时机含手续费") | [Go](../problems/best-time-to-buy-and-sell-stock-with-transaction-fee) | Medium |
-| <span id="715">715</span> | [Range Module](https://leetcode.com/problems/range-module "Range 模块") | [Go](../problems/range-module) | Hard |
-| <span id="716">716</span> | [Max Stack](https://leetcode.com/problems/max-stack "最大栈") 🔒 | [Go](../problems/max-stack) | Easy |
-| <span id="717">717</span> | [1-bit and 2-bit Characters](https://leetcode.com/problems/1-bit-and-2-bit-characters "1比特与2比特字符") | [Go](../problems/1-bit-and-2-bit-characters) | Easy |
-| <span id="718">718</span> | [Maximum Length of Repeated Subarray](https://leetcode.com/problems/maximum-length-of-repeated-subarray "最长重复子数组") | [Go](../problems/maximum-length-of-repeated-subarray) | Medium |
-| <span id="719">719</span> | [Find K-th Smallest Pair Distance](https://leetcode.com/problems/find-k-th-smallest-pair-distance "找出第 k 小的距离对") | [Go](../problems/find-k-th-smallest-pair-distance) | Hard |
-| <span id="720">720</span> | [Longest Word in Dictionary](https://leetcode.com/problems/longest-word-in-dictionary "词典中最长的单词") | [Go](../problems/longest-word-in-dictionary) | Medium |
-| <span id="721">721</span> | [Accounts Merge](https://leetcode.com/problems/accounts-merge "账户合并") | [Go](../problems/accounts-merge) | Medium |
-| <span id="722">722</span> | [Remove Comments](https://leetcode.com/problems/remove-comments "删除注释") | [Go](../problems/remove-comments) | Medium |
-| <span id="723">723</span> | [Candy Crush](https://leetcode.com/problems/candy-crush "粉碎糖果") 🔒 | [Go](../problems/candy-crush) | Medium |
-| <span id="724">724</span> | [Find Pivot Index](https://leetcode.com/problems/find-pivot-index "寻找数组的中心下标") | [Go](../problems/find-pivot-index) | Easy |
-| <span id="725">725</span> | [Split Linked List in Parts](https://leetcode.com/problems/split-linked-list-in-parts "分隔链表") | [Go](../problems/split-linked-list-in-parts) | Medium |
-| <span id="726">726</span> | [Number of Atoms](https://leetcode.com/problems/number-of-atoms "原子的数量") | [Go](../problems/number-of-atoms) | Hard |
-| <span id="727">727</span> | [Minimum Window Subsequence](https://leetcode.com/problems/minimum-window-subsequence "最小窗口子序列") 🔒 | [Go](../problems/minimum-window-subsequence) | Hard |
-| <span id="728">728</span> | [Self Dividing Numbers](https://leetcode.com/problems/self-dividing-numbers "自除数") | [Go](../problems/self-dividing-numbers) | Easy |
-| <span id="729">729</span> | [My Calendar I](https://leetcode.com/problems/my-calendar-i "我的日程安排表 I") | [Go](../problems/my-calendar-i) | Medium |
-| <span id="730">730</span> | [Count Different Palindromic Subsequences](https://leetcode.com/problems/count-different-palindromic-subsequences "统计不同回文子序列") | [Go](../problems/count-different-palindromic-subsequences) | Hard |
-| <span id="731">731</span> | [My Calendar II](https://leetcode.com/problems/my-calendar-ii "我的日程安排表 II") | [Go](../problems/my-calendar-ii) | Medium |
-| <span id="732">732</span> | [My Calendar III](https://leetcode.com/problems/my-calendar-iii "我的日程安排表 III") | [Go](../problems/my-calendar-iii) | Hard |
-| <span id="733">733</span> | [Flood Fill](https://leetcode.com/problems/flood-fill "图像渲染") | [Go](../problems/flood-fill) | Easy |
-| <span id="734">734</span> | [Sentence Similarity](https://leetcode.com/problems/sentence-similarity "句子相似性") 🔒 | [Go](../problems/sentence-similarity) | Easy |
-| <span id="735">735</span> | [Asteroid Collision](https://leetcode.com/problems/asteroid-collision "行星碰撞") | [Go](../problems/asteroid-collision) | Medium |
-| <span id="736">736</span> | [Parse Lisp Expression](https://leetcode.com/problems/parse-lisp-expression "Lisp 语法解析") | [Go](../problems/parse-lisp-expression) | Hard |
-| <span id="737">737</span> | [Sentence Similarity II](https://leetcode.com/problems/sentence-similarity-ii "句子相似性 II") 🔒 | [Go](../problems/sentence-similarity-ii) | Medium |
-| <span id="738">738</span> | [Monotone Increasing Digits](https://leetcode.com/problems/monotone-increasing-digits "单调递增的数字") | [Go](../problems/monotone-increasing-digits) | Medium |
-| <span id="739">739</span> | [Daily Temperatures](https://leetcode.com/problems/daily-temperatures "每日温度") | [Go](../problems/daily-temperatures) | Medium |
-| <span id="740">740</span> | [Delete and Earn](https://leetcode.com/problems/delete-and-earn "删除并获得点数") | [Go](../problems/delete-and-earn) | Medium |
-| <span id="741">741</span> | [Cherry Pickup](https://leetcode.com/problems/cherry-pickup "摘樱桃") | [Go](../problems/cherry-pickup) | Hard |
-| <span id="742">742</span> | [Closest Leaf in a Binary Tree](https://leetcode.com/problems/closest-leaf-in-a-binary-tree "二叉树最近的叶节点") 🔒 | [Go](../problems/closest-leaf-in-a-binary-tree) | Medium |
-| <span id="743">743</span> | [Network Delay Time](https://leetcode.com/problems/network-delay-time "网络延迟时间") | [Go](../problems/network-delay-time) | Medium |
-| <span id="744">744</span> | [Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target "寻找比目标字母大的最小字母") | [Go](../problems/find-smallest-letter-greater-than-target) | Easy |
-| <span id="745">745</span> | [Prefix and Suffix Search](https://leetcode.com/problems/prefix-and-suffix-search "前缀和后缀搜索") | [Go](../problems/prefix-and-suffix-search) | Hard |
-| <span id="746">746</span> | [Min Cost Climbing Stairs](https://leetcode.com/problems/min-cost-climbing-stairs "使用最小花费爬楼梯") | [Go](../problems/min-cost-climbing-stairs) | Easy |
-| <span id="747">747</span> | [Largest Number At Least Twice of Others](https://leetcode.com/problems/largest-number-at-least-twice-of-others "至少是其他数字两倍的最大数") | [Go](../problems/largest-number-at-least-twice-of-others) | Easy |
-| <span id="748">748</span> | [Shortest Completing Word](https://leetcode.com/problems/shortest-completing-word "最短补全词") | [Go](../problems/shortest-completing-word) | Easy |
-| <span id="749">749</span> | [Contain Virus](https://leetcode.com/problems/contain-virus "隔离病毒") | [Go](../problems/contain-virus) | Hard |
-| <span id="750">750</span> | [Number Of Corner Rectangles](https://leetcode.com/problems/number-of-corner-rectangles "角矩形的数量") 🔒 | [Go](../problems/number-of-corner-rectangles) | Medium |
-| <span id="751">751</span> | [IP to CIDR](https://leetcode.com/problems/ip-to-cidr "IP 到 CIDR") 🔒 | [Go](../problems/ip-to-cidr) | Medium |
-| <span id="752">752</span> | [Open the Lock](https://leetcode.com/problems/open-the-lock "打开转盘锁") | [Go](../problems/open-the-lock) | Medium |
-| <span id="753">753</span> | [Cracking the Safe](https://leetcode.com/problems/cracking-the-safe "破解保险箱") | [Go](../problems/cracking-the-safe) | Hard |
-| <span id="754">754</span> | [Reach a Number](https://leetcode.com/problems/reach-a-number "到达终点数字") | [Go](../problems/reach-a-number) | Medium |
-| <span id="755">755</span> | [Pour Water](https://leetcode.com/problems/pour-water "倒水") 🔒 | [Go](../problems/pour-water) | Medium |
-| <span id="756">756</span> | [Pyramid Transition Matrix](https://leetcode.com/problems/pyramid-transition-matrix "金字塔转换矩阵") | [Go](../problems/pyramid-transition-matrix) | Medium |
-| <span id="757">757</span> | [Set Intersection Size At Least Two](https://leetcode.com/problems/set-intersection-size-at-least-two "设置交集大小至少为2") | [Go](../problems/set-intersection-size-at-least-two) | Hard |
-| <span id="758">758</span> | [Bold Words in String](https://leetcode.com/problems/bold-words-in-string "字符串中的加粗单词") 🔒 | [Go](../problems/bold-words-in-string) | Medium |
-| <span id="759">759</span> | [Employee Free Time](https://leetcode.com/problems/employee-free-time "员工空闲时间") 🔒 | [Go](../problems/employee-free-time) | Hard |
-| <span id="760">760</span> | [Find Anagram Mappings](https://leetcode.com/problems/find-anagram-mappings "找出变位映射") 🔒 | [Go](../problems/find-anagram-mappings) | Easy |
-| <span id="761">761</span> | [Special Binary String](https://leetcode.com/problems/special-binary-string "特殊的二进制序列") | [Go](../problems/special-binary-string) | Hard |
-| <span id="762">762</span> | [Prime Number of Set Bits in Binary Representation](https://leetcode.com/problems/prime-number-of-set-bits-in-binary-representation "二进制表示中质数个计算置位") | [Go](../problems/prime-number-of-set-bits-in-binary-representation) | Easy |
-| <span id="763">763</span> | [Partition Labels](https://leetcode.com/problems/partition-labels "划分字母区间") | [Go](../problems/partition-labels) | Medium |
-| <span id="764">764</span> | [Largest Plus Sign](https://leetcode.com/problems/largest-plus-sign "最大加号标志") | [Go](../problems/largest-plus-sign) | Medium |
-| <span id="765">765</span> | [Couples Holding Hands](https://leetcode.com/problems/couples-holding-hands "情侣牵手") | [Go](../problems/couples-holding-hands) | Hard |
-| <span id="766">766</span> | [Toeplitz Matrix](https://leetcode.com/problems/toeplitz-matrix "托普利茨矩阵") | [Go](../problems/toeplitz-matrix) | Easy |
-| <span id="767">767</span> | [Reorganize String](https://leetcode.com/problems/reorganize-string "重构字符串") | [Go](../problems/reorganize-string) | Medium |
-| <span id="768">768</span> | [Max Chunks To Make Sorted II](https://leetcode.com/problems/max-chunks-to-make-sorted-ii "最多能完成排序的块 II") | [Go](../problems/max-chunks-to-make-sorted-ii) | Hard |
-| <span id="769">769</span> | [Max Chunks To Make Sorted](https://leetcode.com/problems/max-chunks-to-make-sorted "最多能完成排序的块") | [Go](../problems/max-chunks-to-make-sorted) | Medium |
-| <span id="770">770</span> | [Basic Calculator IV](https://leetcode.com/problems/basic-calculator-iv "基本计算器 IV") | [Go](../problems/basic-calculator-iv) | Hard |
-| <span id="771">771</span> | [Jewels and Stones](https://leetcode.com/problems/jewels-and-stones "宝石与石头") | [Go](../problems/jewels-and-stones) | Easy |
-| <span id="772">772</span> | [Basic Calculator III](https://leetcode.com/problems/basic-calculator-iii "基本计算器 III") 🔒 | [Go](../problems/basic-calculator-iii) | Hard |
-| <span id="773">773</span> | [Sliding Puzzle](https://leetcode.com/problems/sliding-puzzle "滑动谜题") | [Go](../problems/sliding-puzzle) | Hard |
-| <span id="774">774</span> | [Minimize Max Distance to Gas Station](https://leetcode.com/problems/minimize-max-distance-to-gas-station "最小化去加油站的最大距离") 🔒 | [Go](../problems/minimize-max-distance-to-gas-station) | Hard |
-| <span id="775">775</span> | [Global and Local Inversions](https://leetcode.com/problems/global-and-local-inversions "全局倒置与局部倒置") | [Go](../problems/global-and-local-inversions) | Medium |
-| <span id="776">776</span> | [Split BST](https://leetcode.com/problems/split-bst "拆分二叉搜索树") 🔒 | [Go](../problems/split-bst) | Medium |
-| <span id="777">777</span> | [Swap Adjacent in LR String](https://leetcode.com/problems/swap-adjacent-in-lr-string "在LR字符串中交换相邻字符") | [Go](../problems/swap-adjacent-in-lr-string) | Medium |
-| <span id="778">778</span> | [Swim in Rising Water](https://leetcode.com/problems/swim-in-rising-water "水位上升的泳池中游泳") | [Go](../problems/swim-in-rising-water) | Hard |
-| <span id="779">779</span> | [K-th Symbol in Grammar](https://leetcode.com/problems/k-th-symbol-in-grammar "第K个语法符号") | [Go](../problems/k-th-symbol-in-grammar) | Medium |
-| <span id="780">780</span> | [Reaching Points](https://leetcode.com/problems/reaching-points "到达终点") | [Go](../problems/reaching-points) | Hard |
-| <span id="781">781</span> | [Rabbits in Forest](https://leetcode.com/problems/rabbits-in-forest "森林中的兔子") | [Go](../problems/rabbits-in-forest) | Medium |
-| <span id="782">782</span> | [Transform to Chessboard](https://leetcode.com/problems/transform-to-chessboard "变为棋盘") | [Go](../problems/transform-to-chessboard) | Hard |
-| <span id="783">783</span> | [Minimum Distance Between BST Nodes](https://leetcode.com/problems/minimum-distance-between-bst-nodes "二叉搜索树节点最小距离") | [Go](../problems/minimum-distance-between-bst-nodes) | Easy |
-| <span id="784">784</span> | [Letter Case Permutation](https://leetcode.com/problems/letter-case-permutation "字母大小写全排列") | [Go](../problems/letter-case-permutation) | Medium |
-| <span id="785">785</span> | [Is Graph Bipartite?](https://leetcode.com/problems/is-graph-bipartite "判断二分图") | [Go](../problems/is-graph-bipartite) | Medium |
-| <span id="786">786</span> | [K-th Smallest Prime Fraction](https://leetcode.com/problems/k-th-smallest-prime-fraction "第 K 个最小的素数分数") | [Go](../problems/k-th-smallest-prime-fraction) | Hard |
-| <span id="787">787</span> | [Cheapest Flights Within K Stops](https://leetcode.com/problems/cheapest-flights-within-k-stops "K 站中转内最便宜的航班") | [Go](../problems/cheapest-flights-within-k-stops) | Medium |
-| <span id="788">788</span> | [Rotated Digits](https://leetcode.com/problems/rotated-digits "旋转数字") | [Go](../problems/rotated-digits) | Medium |
-| <span id="789">789</span> | [Escape The Ghosts](https://leetcode.com/problems/escape-the-ghosts "逃脱阻碍者") | [Go](../problems/escape-the-ghosts) | Medium |
-| <span id="790">790</span> | [Domino and Tromino Tiling](https://leetcode.com/problems/domino-and-tromino-tiling "多米诺和托米诺平铺") | [Go](../problems/domino-and-tromino-tiling) | Medium |
-| <span id="791">791</span> | [Custom Sort String](https://leetcode.com/problems/custom-sort-string "自定义字符串排序") | [Go](../problems/custom-sort-string) | Medium |
-| <span id="792">792</span> | [Number of Matching Subsequences](https://leetcode.com/problems/number-of-matching-subsequences "匹配子序列的单词数") | [Go](../problems/number-of-matching-subsequences) | Medium |
-| <span id="793">793</span> | [Preimage Size of Factorial Zeroes Function](https://leetcode.com/problems/preimage-size-of-factorial-zeroes-function "阶乘函数后 K 个零") | [Go](../problems/preimage-size-of-factorial-zeroes-function) | Hard |
-| <span id="794">794</span> | [Valid Tic-Tac-Toe State](https://leetcode.com/problems/valid-tic-tac-toe-state "有效的井字游戏") | [Go](../problems/valid-tic-tac-toe-state) | Medium |
-| <span id="795">795</span> | [Number of Subarrays with Bounded Maximum](https://leetcode.com/problems/number-of-subarrays-with-bounded-maximum "区间子数组个数") | [Go](../problems/number-of-subarrays-with-bounded-maximum) | Medium |
-| <span id="796">796</span> | [Rotate String](https://leetcode.com/problems/rotate-string "旋转字符串") | [Go](../problems/rotate-string) | Easy |
-| <span id="797">797</span> | [All Paths From Source to Target](https://leetcode.com/problems/all-paths-from-source-to-target "所有可能的路径") | [Go](../problems/all-paths-from-source-to-target) | Medium |
-| <span id="798">798</span> | [Smallest Rotation with Highest Score](https://leetcode.com/problems/smallest-rotation-with-highest-score "得分最高的最小轮调") | [Go](../problems/smallest-rotation-with-highest-score) | Hard |
-| <span id="799">799</span> | [Champagne Tower](https://leetcode.com/problems/champagne-tower "香槟塔") | [Go](../problems/champagne-tower) | Medium |
-| <span id="800">800</span> | [Similar RGB Color](https://leetcode.com/problems/similar-rgb-color "相似 RGB 颜色") 🔒 | [Go](../problems/similar-rgb-color) | Easy |
-| <span id="801">801</span> | [Minimum Swaps To Make Sequences Increasing](https://leetcode.com/problems/minimum-swaps-to-make-sequences-increasing "使序列递增的最小交换次数") | [Go](../problems/minimum-swaps-to-make-sequences-increasing) | Hard |
-| <span id="802">802</span> | [Find Eventual Safe States](https://leetcode.com/problems/find-eventual-safe-states "找到最终的安全状态") | [Go](../problems/find-eventual-safe-states) | Medium |
-| <span id="803">803</span> | [Bricks Falling When Hit](https://leetcode.com/problems/bricks-falling-when-hit "打砖块") | [Go](../problems/bricks-falling-when-hit) | Hard |
-| <span id="804">804</span> | [Unique Morse Code Words](https://leetcode.com/problems/unique-morse-code-words "唯一摩尔斯密码词") | [Go](../problems/unique-morse-code-words) | Easy |
-| <span id="805">805</span> | [Split Array With Same Average](https://leetcode.com/problems/split-array-with-same-average "数组的均值分割") | [Go](../problems/split-array-with-same-average) | Hard |
-| <span id="806">806</span> | [Number of Lines To Write String](https://leetcode.com/problems/number-of-lines-to-write-string "写字符串需要的行数") | [Go](../problems/number-of-lines-to-write-string) | Easy |
-| <span id="807">807</span> | [Max Increase to Keep City Skyline](https://leetcode.com/problems/max-increase-to-keep-city-skyline "保持城市天际线") | [Go](../problems/max-increase-to-keep-city-skyline) | Medium |
-| <span id="808">808</span> | [Soup Servings](https://leetcode.com/problems/soup-servings "分汤") | [Go](../problems/soup-servings) | Medium |
-| <span id="809">809</span> | [Expressive Words](https://leetcode.com/problems/expressive-words "情感丰富的文字") | [Go](../problems/expressive-words) | Medium |
-| <span id="810">810</span> | [Chalkboard XOR Game](https://leetcode.com/problems/chalkboard-xor-game "黑板异或游戏") | [Go](../problems/chalkboard-xor-game) | Hard |
-| <span id="811">811</span> | [Subdomain Visit Count](https://leetcode.com/problems/subdomain-visit-count "子域名访问计数") | [Go](../problems/subdomain-visit-count) | Medium |
-| <span id="812">812</span> | [Largest Triangle Area](https://leetcode.com/problems/largest-triangle-area "最大三角形面积") | [Go](../problems/largest-triangle-area) | Easy |
-| <span id="813">813</span> | [Largest Sum of Averages](https://leetcode.com/problems/largest-sum-of-averages "最大平均值和的分组") | [Go](../problems/largest-sum-of-averages) | Medium |
-| <span id="814">814</span> | [Binary Tree Pruning](https://leetcode.com/problems/binary-tree-pruning "二叉树剪枝") | [Go](../problems/binary-tree-pruning) | Medium |
-| <span id="815">815</span> | [Bus Routes](https://leetcode.com/problems/bus-routes "公交路线") | [Go](../problems/bus-routes) | Hard |
-| <span id="816">816</span> | [Ambiguous Coordinates](https://leetcode.com/problems/ambiguous-coordinates "模糊坐标") | [Go](../problems/ambiguous-coordinates) | Medium |
-| <span id="817">817</span> | [Linked List Components](https://leetcode.com/problems/linked-list-components "链表组件") | [Go](../problems/linked-list-components) | Medium |
-| <span id="818">818</span> | [Race Car](https://leetcode.com/problems/race-car "赛车") | [Go](../problems/race-car) | Hard |
-| <span id="819">819</span> | [Most Common Word](https://leetcode.com/problems/most-common-word "最常见的单词") | [Go](../problems/most-common-word) | Easy |
-| <span id="820">820</span> | [Short Encoding of Words](https://leetcode.com/problems/short-encoding-of-words "单词的压缩编码") | [Go](../problems/short-encoding-of-words) | Medium |
-| <span id="821">821</span> | [Shortest Distance to a Character](https://leetcode.com/problems/shortest-distance-to-a-character "字符的最短距离") | [Go](../problems/shortest-distance-to-a-character) | Easy |
-| <span id="822">822</span> | [Card Flipping Game](https://leetcode.com/problems/card-flipping-game "翻转卡片游戏") | [Go](../problems/card-flipping-game) | Medium |
-| <span id="823">823</span> | [Binary Trees With Factors](https://leetcode.com/problems/binary-trees-with-factors "带因子的二叉树") | [Go](../problems/binary-trees-with-factors) | Medium |
-| <span id="824">824</span> | [Goat Latin](https://leetcode.com/problems/goat-latin "山羊拉丁文") | [Go](../problems/goat-latin) | Easy |
-| <span id="825">825</span> | [Friends Of Appropriate Ages](https://leetcode.com/problems/friends-of-appropriate-ages "适龄的朋友") | [Go](../problems/friends-of-appropriate-ages) | Medium |
-| <span id="826">826</span> | [Most Profit Assigning Work](https://leetcode.com/problems/most-profit-assigning-work "安排工作以达到最大收益") | [Go](../problems/most-profit-assigning-work) | Medium |
-| <span id="827">827</span> | [Making A Large Island](https://leetcode.com/problems/making-a-large-island "最大人工岛") | [Go](../problems/making-a-large-island) | Hard |
-| <span id="828">828</span> | [Count Unique Characters of All Substrings of a Given String](https://leetcode.com/problems/count-unique-characters-of-all-substrings-of-a-given-string "统计子串中的唯一字符") | [Go](../problems/count-unique-characters-of-all-substrings-of-a-given-string) | Hard |
-| <span id="829">829</span> | [Consecutive Numbers Sum](https://leetcode.com/problems/consecutive-numbers-sum "连续整数求和") | [Go](../problems/consecutive-numbers-sum) | Hard |
-| <span id="830">830</span> | [Positions of Large Groups](https://leetcode.com/problems/positions-of-large-groups "较大分组的位置") | [Go](../problems/positions-of-large-groups) | Easy |
-| <span id="831">831</span> | [Masking Personal Information](https://leetcode.com/problems/masking-personal-information "隐藏个人信息") | [Go](../problems/masking-personal-information) | Medium |
-| <span id="832">832</span> | [Flipping an Image](https://leetcode.com/problems/flipping-an-image "翻转图像") | [Go](../problems/flipping-an-image) | Easy |
-| <span id="833">833</span> | [Find And Replace in String](https://leetcode.com/problems/find-and-replace-in-string "字符串中的查找与替换") | [Go](../problems/find-and-replace-in-string) | Medium |
-| <span id="834">834</span> | [Sum of Distances in Tree](https://leetcode.com/problems/sum-of-distances-in-tree "树中距离之和") | [Go](../problems/sum-of-distances-in-tree) | Hard |
-| <span id="835">835</span> | [Image Overlap](https://leetcode.com/problems/image-overlap "图像重叠") | [Go](../problems/image-overlap) | Medium |
-| <span id="836">836</span> | [Rectangle Overlap](https://leetcode.com/problems/rectangle-overlap "矩形重叠") | [Go](../problems/rectangle-overlap) | Easy |
-| <span id="837">837</span> | [New 21 Game](https://leetcode.com/problems/new-21-game "新 21 点") | [Go](../problems/new-21-game) | Medium |
-| <span id="838">838</span> | [Push Dominoes](https://leetcode.com/problems/push-dominoes "推多米诺") | [Go](../problems/push-dominoes) | Medium |
-| <span id="839">839</span> | [Similar String Groups](https://leetcode.com/problems/similar-string-groups "相似字符串组") | [Go](../problems/similar-string-groups) | Hard |
-| <span id="840">840</span> | [Magic Squares In Grid](https://leetcode.com/problems/magic-squares-in-grid "矩阵中的幻方") | [Go](../problems/magic-squares-in-grid) | Medium |
-| <span id="841">841</span> | [Keys and Rooms](https://leetcode.com/problems/keys-and-rooms "钥匙和房间") | [Go](../problems/keys-and-rooms) | Medium |
-| <span id="842">842</span> | [Split Array into Fibonacci Sequence](https://leetcode.com/problems/split-array-into-fibonacci-sequence "将数组拆分成斐波那契序列") | [Go](../problems/split-array-into-fibonacci-sequence) | Medium |
-| <span id="843">843</span> | [Guess the Word](https://leetcode.com/problems/guess-the-word "猜猜这个单词") | [Go](../problems/guess-the-word) | Hard |
-| <span id="844">844</span> | [Backspace String Compare](https://leetcode.com/problems/backspace-string-compare "比较含退格的字符串") | [Go](../problems/backspace-string-compare) | Easy |
-| <span id="845">845</span> | [Longest Mountain in Array](https://leetcode.com/problems/longest-mountain-in-array "数组中的最长山脉") | [Go](../problems/longest-mountain-in-array) | Medium |
-| <span id="846">846</span> | [Hand of Straights](https://leetcode.com/problems/hand-of-straights "一手顺子") | [Go](../problems/hand-of-straights) | Medium |
-| <span id="847">847</span> | [Shortest Path Visiting All Nodes](https://leetcode.com/problems/shortest-path-visiting-all-nodes "访问所有节点的最短路径") | [Go](../problems/shortest-path-visiting-all-nodes) | Hard |
-| <span id="848">848</span> | [Shifting Letters](https://leetcode.com/problems/shifting-letters "字母移位") | [Go](../problems/shifting-letters) | Medium |
-| <span id="849">849</span> | [Maximize Distance to Closest Person](https://leetcode.com/problems/maximize-distance-to-closest-person "到最近的人的最大距离") | [Go](../problems/maximize-distance-to-closest-person) | Medium |
-| <span id="850">850</span> | [Rectangle Area II](https://leetcode.com/problems/rectangle-area-ii "矩形面积 II") | [Go](../problems/rectangle-area-ii) | Hard |
-| <span id="851">851</span> | [Loud and Rich](https://leetcode.com/problems/loud-and-rich "喧闹和富有") | [Go](../problems/loud-and-rich) | Medium |
-| <span id="852">852</span> | [Peak Index in a Mountain Array](https://leetcode.com/problems/peak-index-in-a-mountain-array "山脉数组的峰顶索引") | [Go](../problems/peak-index-in-a-mountain-array) | Easy |
-| <span id="853">853</span> | [Car Fleet](https://leetcode.com/problems/car-fleet "车队") | [Go](../problems/car-fleet) | Medium |
-| <span id="854">854</span> | [K-Similar Strings](https://leetcode.com/problems/k-similar-strings "相似度为 K 的字符串") | [Go](../problems/k-similar-strings) | Hard |
-| <span id="855">855</span> | [Exam Room](https://leetcode.com/problems/exam-room "考场就座") | [Go](../problems/exam-room) | Medium |
-| <span id="856">856</span> | [Score of Parentheses](https://leetcode.com/problems/score-of-parentheses "括号的分数") | [Go](../problems/score-of-parentheses) | Medium |
-| <span id="857">857</span> | [Minimum Cost to Hire K Workers](https://leetcode.com/problems/minimum-cost-to-hire-k-workers "雇佣 K 名工人的最低成本") | [Go](../problems/minimum-cost-to-hire-k-workers) | Hard |
-| <span id="858">858</span> | [Mirror Reflection](https://leetcode.com/problems/mirror-reflection "镜面反射") | [Go](../problems/mirror-reflection) | Medium |
-| <span id="859">859</span> | [Buddy Strings](https://leetcode.com/problems/buddy-strings "亲密字符串") | [Go](../problems/buddy-strings) | Easy |
-| <span id="860">860</span> | [Lemonade Change](https://leetcode.com/problems/lemonade-change "柠檬水找零") | [Go](../problems/lemonade-change) | Easy |
-| <span id="861">861</span> | [Score After Flipping Matrix](https://leetcode.com/problems/score-after-flipping-matrix "翻转矩阵后的得分") | [Go](../problems/score-after-flipping-matrix) | Medium |
-| <span id="862">862</span> | [Shortest Subarray with Sum at Least K](https://leetcode.com/problems/shortest-subarray-with-sum-at-least-k "和至少为 K 的最短子数组") | [Go](../problems/shortest-subarray-with-sum-at-least-k) | Hard |
-| <span id="863">863</span> | [All Nodes Distance K in Binary Tree](https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree "二叉树中所有距离为 K 的结点") | [Go](../problems/all-nodes-distance-k-in-binary-tree) | Medium |
-| <span id="864">864</span> | [Shortest Path to Get All Keys](https://leetcode.com/problems/shortest-path-to-get-all-keys "获取所有钥匙的最短路径") | [Go](../problems/shortest-path-to-get-all-keys) | Hard |
-| <span id="865">865</span> | [Smallest Subtree with all the Deepest Nodes](https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes "具有所有最深节点的最小子树") | [Go](../problems/smallest-subtree-with-all-the-deepest-nodes) | Medium |
-| <span id="866">866</span> | [Prime Palindrome](https://leetcode.com/problems/prime-palindrome "回文素数") | [Go](../problems/prime-palindrome) | Medium |
-| <span id="867">867</span> | [Transpose Matrix](https://leetcode.com/problems/transpose-matrix "转置矩阵") | [Go](../problems/transpose-matrix) | Easy |
-| <span id="868">868</span> | [Binary Gap](https://leetcode.com/problems/binary-gap "二进制间距") | [Go](../problems/binary-gap) | Easy |
-| <span id="869">869</span> | [Reordered Power of 2](https://leetcode.com/problems/reordered-power-of-2 "重新排序得到 2 的幂") | [Go](../problems/reordered-power-of-2) | Medium |
-| <span id="870">870</span> | [Advantage Shuffle](https://leetcode.com/problems/advantage-shuffle "优势洗牌") | [Go](../problems/advantage-shuffle) | Medium |
-| <span id="871">871</span> | [Minimum Number of Refueling Stops](https://leetcode.com/problems/minimum-number-of-refueling-stops "最低加油次数") | [Go](../problems/minimum-number-of-refueling-stops) | Hard |
-| <span id="872">872</span> | [Leaf-Similar Trees](https://leetcode.com/problems/leaf-similar-trees "叶子相似的树") | [Go](../problems/leaf-similar-trees) | Easy |
-| <span id="873">873</span> | [Length of Longest Fibonacci Subsequence](https://leetcode.com/problems/length-of-longest-fibonacci-subsequence "最长的斐波那契子序列的长度") | [Go](../problems/length-of-longest-fibonacci-subsequence) | Medium |
-| <span id="874">874</span> | [Walking Robot Simulation](https://leetcode.com/problems/walking-robot-simulation "模拟行走机器人") | [Go](../problems/walking-robot-simulation) | Medium |
-| <span id="875">875</span> | [Koko Eating Bananas](https://leetcode.com/problems/koko-eating-bananas "爱吃香蕉的珂珂") | [Go](../problems/koko-eating-bananas) | Medium |
-| <span id="876">876</span> | [Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list "链表的中间结点") | [Go](../problems/middle-of-the-linked-list) | Easy |
-| <span id="877">877</span> | [Stone Game](https://leetcode.com/problems/stone-game "石子游戏") | [Go](../problems/stone-game) | Medium |
-| <span id="878">878</span> | [Nth Magical Number](https://leetcode.com/problems/nth-magical-number "第 N 个神奇数字") | [Go](../problems/nth-magical-number) | Hard |
-| <span id="879">879</span> | [Profitable Schemes](https://leetcode.com/problems/profitable-schemes "盈利计划") | [Go](../problems/profitable-schemes) | Hard |
-| <span id="880">880</span> | [Decoded String at Index](https://leetcode.com/problems/decoded-string-at-index "索引处的解码字符串") | [Go](../problems/decoded-string-at-index) | Medium |
-| <span id="881">881</span> | [Boats to Save People](https://leetcode.com/problems/boats-to-save-people "救生艇") | [Go](../problems/boats-to-save-people) | Medium |
-| <span id="882">882</span> | [Reachable Nodes In Subdivided Graph](https://leetcode.com/problems/reachable-nodes-in-subdivided-graph "细分图中的可到达结点") | [Go](../problems/reachable-nodes-in-subdivided-graph) | Hard |
-| <span id="883">883</span> | [Projection Area of 3D Shapes](https://leetcode.com/problems/projection-area-of-3d-shapes "三维形体投影面积") | [Go](../problems/projection-area-of-3d-shapes) | Easy |
-| <span id="884">884</span> | [Uncommon Words from Two Sentences](https://leetcode.com/problems/uncommon-words-from-two-sentences "两句话中的不常见单词") | [Go](../problems/uncommon-words-from-two-sentences) | Easy |
-| <span id="885">885</span> | [Spiral Matrix III](https://leetcode.com/problems/spiral-matrix-iii "螺旋矩阵 III") | [Go](../problems/spiral-matrix-iii) | Medium |
-| <span id="886">886</span> | [Possible Bipartition](https://leetcode.com/problems/possible-bipartition "可能的二分法") | [Go](../problems/possible-bipartition) | Medium |
-| <span id="887">887</span> | [Super Egg Drop](https://leetcode.com/problems/super-egg-drop "鸡蛋掉落") | [Go](../problems/super-egg-drop) | Hard |
-| <span id="888">888</span> | [Fair Candy Swap](https://leetcode.com/problems/fair-candy-swap "公平的糖果交换") | [Go](../problems/fair-candy-swap) | Easy |
-| <span id="889">889</span> | [Construct Binary Tree from Preorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-postorder-traversal "根据前序和后序遍历构造二叉树") | [Go](../problems/construct-binary-tree-from-preorder-and-postorder-traversal) | Medium |
-| <span id="890">890</span> | [Find and Replace Pattern](https://leetcode.com/problems/find-and-replace-pattern "查找和替换模式") | [Go](../problems/find-and-replace-pattern) | Medium |
-| <span id="891">891</span> | [Sum of Subsequence Widths](https://leetcode.com/problems/sum-of-subsequence-widths "子序列宽度之和") | [Go](../problems/sum-of-subsequence-widths) | Hard |
-| <span id="892">892</span> | [Surface Area of 3D Shapes](https://leetcode.com/problems/surface-area-of-3d-shapes "三维形体的表面积") | [Go](../problems/surface-area-of-3d-shapes) | Easy |
-| <span id="893">893</span> | [Groups of Special-Equivalent Strings](https://leetcode.com/problems/groups-of-special-equivalent-strings "特殊等价字符串组") | [Go](../problems/groups-of-special-equivalent-strings) | Medium |
-| <span id="894">894</span> | [All Possible Full Binary Trees](https://leetcode.com/problems/all-possible-full-binary-trees "所有可能的满二叉树") | [Go](../problems/all-possible-full-binary-trees) | Medium |
-| <span id="895">895</span> | [Maximum Frequency Stack](https://leetcode.com/problems/maximum-frequency-stack "最大频率栈") | [Go](../problems/maximum-frequency-stack) | Hard |
-| <span id="896">896</span> | [Monotonic Array](https://leetcode.com/problems/monotonic-array "单调数列") | [Go](../problems/monotonic-array) | Easy |
-| <span id="897">897</span> | [Increasing Order Search Tree](https://leetcode.com/problems/increasing-order-search-tree "递增顺序搜索树") | [Go](../problems/increasing-order-search-tree) | Easy |
-| <span id="898">898</span> | [Bitwise ORs of Subarrays](https://leetcode.com/problems/bitwise-ors-of-subarrays "子数组按位或操作") | [Go](../problems/bitwise-ors-of-subarrays) | Medium |
-| <span id="899">899</span> | [Orderly Queue](https://leetcode.com/problems/orderly-queue "有序队列") | [Go](../problems/orderly-queue) | Hard |
-| <span id="900">900</span> | [RLE Iterator](https://leetcode.com/problems/rle-iterator "RLE 迭代器") | [Go](../problems/rle-iterator) | Medium |
diff --git a/readme/901-1200.md b/readme/901-1200.md
deleted file mode 100644
index d782e4e6a..000000000
--- a/readme/901-1200.md
+++ /dev/null
@@ -1,388 +0,0 @@
-<!--|This file generated by command(leetcode readme); DO NOT EDIT.         |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-# [LeetCode](https://awesee.github.io/leetcode)
-LeetCode Problems' Solutions
-[[力扣](https://awesee.github.io/categories/leetcode/) ∙ [话题分类](https://github.com/awesee/leetcode/blob/master/tag/README.md)]
-
-[![Go](https://github.com/awesee/leetcode/workflows/Go/badge.svg)](https://github.com/awesee/leetcode/actions)
-[![codecov](https://codecov.io/gh/awesee/leetcode/branch/master/graph/badge.svg)](https://codecov.io/gh/awesee/leetcode)
-[![Go Report Card](https://goreportcard.com/badge/github.com/awesee/leetcode)](https://goreportcard.com/report/github.com/awesee/leetcode)
-[![GitHub contributors](https://img.shields.io/github/contributors/awesee/leetcode.svg)](https://github.com/awesee/leetcode/graphs/contributors)
-[![license](https://img.shields.io/github/license/awesee/leetcode.svg)](https://github.com/awesee/leetcode/blob/master/LICENSE)
-[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fawesee%2Fleetcode.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fawesee%2Fleetcode?ref=badge_shield)
-[![Join the chat](https://badges.gitter.im/awesee/leetcode.svg)](https://gitter.im/awesee/leetcode?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-
-<table><thead>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#1">[1-50]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#51">[51-100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#101">[101-150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#151">[151-200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#201">[201-250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1-300.md#251">[251-300]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#301">[301-350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#351">[351-400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#401">[401-450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#451">[451-500]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#501">[501-550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/301-600.md#551">[551-600]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#601">[601-650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#651">[651-700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#701">[701-750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#751">[751-800]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#801">[801-850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/601-900.md#851">[851-900]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#901">[901-950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#951">[951-1000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1001">[1001-1050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1051">[1051-1100]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1101">[1101-1150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/901-1200.md#1151">[1151-1200]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1201">[1201-1250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1251">[1251-1300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1301">[1301-1350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1351">[1351-1400]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1401">[1401-1450]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1201-1500.md#1451">[1451-1500]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1501">[1501-1550]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1551">[1551-1600]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1601">[1601-1650]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1651">[1651-1700]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1701">[1701-1750]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/readme/1501-1800.md#1751">[1751-1800]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1850">[1801-1850]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1900">[1851-1900]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#1950">[1901-1950]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2000">[1951-2000]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2050">[2001-2050]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2100">[2051-2100]</a></th>
-</tr>
-<tr>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2150">[2101-2150]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2200">[2151-2200]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2250">[2201-2250]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2300">[2251-2300]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2350">[2301-2350]</a></th>
-	<th align="center"><a href="https://github.com/awesee/leetcode/tree/main/README.md#2400">[2351-2400]</a></th>
-</tr>
-</thead></table>
-
-| # | Title | Solution | Difficulty |
-| :-: | - | - | :-: |
-| <span id="901">901</span> | [Online Stock Span](https://leetcode.com/problems/online-stock-span "股票价格跨度") | [Go](../problems/online-stock-span) | Medium |
-| <span id="902">902</span> | [Numbers At Most N Given Digit Set](https://leetcode.com/problems/numbers-at-most-n-given-digit-set "最大为 N 的数字组合") | [Go](../problems/numbers-at-most-n-given-digit-set) | Hard |
-| <span id="903">903</span> | [Valid Permutations for DI Sequence](https://leetcode.com/problems/valid-permutations-for-di-sequence "DI 序列的有效排列") | [Go](../problems/valid-permutations-for-di-sequence) | Hard |
-| <span id="904">904</span> | [Fruit Into Baskets](https://leetcode.com/problems/fruit-into-baskets "水果成篮") | [Go](../problems/fruit-into-baskets) | Medium |
-| <span id="905">905</span> | [Sort Array By Parity](https://leetcode.com/problems/sort-array-by-parity "按奇偶排序数组") | [Go](../problems/sort-array-by-parity) | Easy |
-| <span id="906">906</span> | [Super Palindromes](https://leetcode.com/problems/super-palindromes "超级回文数") | [Go](../problems/super-palindromes) | Hard |
-| <span id="907">907</span> | [Sum of Subarray Minimums](https://leetcode.com/problems/sum-of-subarray-minimums "子数组的最小值之和") | [Go](../problems/sum-of-subarray-minimums) | Medium |
-| <span id="908">908</span> | [Smallest Range I](https://leetcode.com/problems/smallest-range-i "最小差值 I") | [Go](../problems/smallest-range-i) | Easy |
-| <span id="909">909</span> | [Snakes and Ladders](https://leetcode.com/problems/snakes-and-ladders "蛇梯棋") | [Go](../problems/snakes-and-ladders) | Medium |
-| <span id="910">910</span> | [Smallest Range II](https://leetcode.com/problems/smallest-range-ii "最小差值 II") | [Go](../problems/smallest-range-ii) | Medium |
-| <span id="911">911</span> | [Online Election](https://leetcode.com/problems/online-election "在线选举") | [Go](../problems/online-election) | Medium |
-| <span id="912">912</span> | [Sort an Array](https://leetcode.com/problems/sort-an-array "排序数组") | [Go](../problems/sort-an-array) | Medium |
-| <span id="913">913</span> | [Cat and Mouse](https://leetcode.com/problems/cat-and-mouse "猫和老鼠") | [Go](../problems/cat-and-mouse) | Hard |
-| <span id="914">914</span> | [X of a Kind in a Deck of Cards](https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards "卡牌分组") | [Go](../problems/x-of-a-kind-in-a-deck-of-cards) | Easy |
-| <span id="915">915</span> | [Partition Array into Disjoint Intervals](https://leetcode.com/problems/partition-array-into-disjoint-intervals "分割数组") | [Go](../problems/partition-array-into-disjoint-intervals) | Medium |
-| <span id="916">916</span> | [Word Subsets](https://leetcode.com/problems/word-subsets "单词子集") | [Go](../problems/word-subsets) | Medium |
-| <span id="917">917</span> | [Reverse Only Letters](https://leetcode.com/problems/reverse-only-letters "仅仅反转字母") | [Go](../problems/reverse-only-letters) | Easy |
-| <span id="918">918</span> | [Maximum Sum Circular Subarray](https://leetcode.com/problems/maximum-sum-circular-subarray "环形子数组的最大和") | [Go](../problems/maximum-sum-circular-subarray) | Medium |
-| <span id="919">919</span> | [Complete Binary Tree Inserter](https://leetcode.com/problems/complete-binary-tree-inserter "完全二叉树插入器") | [Go](../problems/complete-binary-tree-inserter) | Medium |
-| <span id="920">920</span> | [Number of Music Playlists](https://leetcode.com/problems/number-of-music-playlists "播放列表的数量") | [Go](../problems/number-of-music-playlists) | Hard |
-| <span id="921">921</span> | [Minimum Add to Make Parentheses Valid](https://leetcode.com/problems/minimum-add-to-make-parentheses-valid "使括号有效的最少添加") | [Go](../problems/minimum-add-to-make-parentheses-valid) | Medium |
-| <span id="922">922</span> | [Sort Array By Parity II](https://leetcode.com/problems/sort-array-by-parity-ii "按奇偶排序数组 II") | [Go](../problems/sort-array-by-parity-ii) | Easy |
-| <span id="923">923</span> | [3Sum With Multiplicity](https://leetcode.com/problems/3sum-with-multiplicity "三数之和的多种可能") | [Go](../problems/3sum-with-multiplicity) | Medium |
-| <span id="924">924</span> | [Minimize Malware Spread](https://leetcode.com/problems/minimize-malware-spread "尽量减少恶意软件的传播") | [Go](../problems/minimize-malware-spread) | Hard |
-| <span id="925">925</span> | [Long Pressed Name](https://leetcode.com/problems/long-pressed-name "长按键入") | [Go](../problems/long-pressed-name) | Easy |
-| <span id="926">926</span> | [Flip String to Monotone Increasing](https://leetcode.com/problems/flip-string-to-monotone-increasing "将字符串翻转到单调递增") | [Go](../problems/flip-string-to-monotone-increasing) | Medium |
-| <span id="927">927</span> | [Three Equal Parts](https://leetcode.com/problems/three-equal-parts "三等分") | [Go](../problems/three-equal-parts) | Hard |
-| <span id="928">928</span> | [Minimize Malware Spread II](https://leetcode.com/problems/minimize-malware-spread-ii "尽量减少恶意软件的传播 II") | [Go](../problems/minimize-malware-spread-ii) | Hard |
-| <span id="929">929</span> | [Unique Email Addresses](https://leetcode.com/problems/unique-email-addresses "独特的电子邮件地址") | [Go](../problems/unique-email-addresses) | Easy |
-| <span id="930">930</span> | [Binary Subarrays With Sum](https://leetcode.com/problems/binary-subarrays-with-sum "和相同的二元子数组") | [Go](../problems/binary-subarrays-with-sum) | Medium |
-| <span id="931">931</span> | [Minimum Falling Path Sum](https://leetcode.com/problems/minimum-falling-path-sum "下降路径最小和") | [Go](../problems/minimum-falling-path-sum) | Medium |
-| <span id="932">932</span> | [Beautiful Array](https://leetcode.com/problems/beautiful-array "漂亮数组") | [Go](../problems/beautiful-array) | Medium |
-| <span id="933">933</span> | [Number of Recent Calls](https://leetcode.com/problems/number-of-recent-calls "最近的请求次数") | [Go](../problems/number-of-recent-calls) | Easy |
-| <span id="934">934</span> | [Shortest Bridge](https://leetcode.com/problems/shortest-bridge "最短的桥") | [Go](../problems/shortest-bridge) | Medium |
-| <span id="935">935</span> | [Knight Dialer](https://leetcode.com/problems/knight-dialer "骑士拨号器") | [Go](../problems/knight-dialer) | Medium |
-| <span id="936">936</span> | [Stamping The Sequence](https://leetcode.com/problems/stamping-the-sequence "戳印序列") | [Go](../problems/stamping-the-sequence) | Hard |
-| <span id="937">937</span> | [Reorder Data in Log Files](https://leetcode.com/problems/reorder-data-in-log-files "重新排列日志文件") | [Go](../problems/reorder-data-in-log-files) | Easy |
-| <span id="938">938</span> | [Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst "二叉搜索树的范围和") | [Go](../problems/range-sum-of-bst) | Easy |
-| <span id="939">939</span> | [Minimum Area Rectangle](https://leetcode.com/problems/minimum-area-rectangle "最小面积矩形") | [Go](../problems/minimum-area-rectangle) | Medium |
-| <span id="940">940</span> | [Distinct Subsequences II](https://leetcode.com/problems/distinct-subsequences-ii "不同的子序列 II") | [Go](../problems/distinct-subsequences-ii) | Hard |
-| <span id="941">941</span> | [Valid Mountain Array](https://leetcode.com/problems/valid-mountain-array "有效的山脉数组") | [Go](../problems/valid-mountain-array) | Easy |
-| <span id="942">942</span> | [DI String Match](https://leetcode.com/problems/di-string-match "增减字符串匹配") | [Go](../problems/di-string-match) | Easy |
-| <span id="943">943</span> | [Find the Shortest Superstring](https://leetcode.com/problems/find-the-shortest-superstring "最短超级串") | [Go](../problems/find-the-shortest-superstring) | Hard |
-| <span id="944">944</span> | [Delete Columns to Make Sorted](https://leetcode.com/problems/delete-columns-to-make-sorted "删列造序") | [Go](../problems/delete-columns-to-make-sorted) | Easy |
-| <span id="945">945</span> | [Minimum Increment to Make Array Unique](https://leetcode.com/problems/minimum-increment-to-make-array-unique "使数组唯一的最小增量") | [Go](../problems/minimum-increment-to-make-array-unique) | Medium |
-| <span id="946">946</span> | [Validate Stack Sequences](https://leetcode.com/problems/validate-stack-sequences "验证栈序列") | [Go](../problems/validate-stack-sequences) | Medium |
-| <span id="947">947</span> | [Most Stones Removed with Same Row or Column](https://leetcode.com/problems/most-stones-removed-with-same-row-or-column "移除最多的同行或同列石头") | [Go](../problems/most-stones-removed-with-same-row-or-column) | Medium |
-| <span id="948">948</span> | [Bag of Tokens](https://leetcode.com/problems/bag-of-tokens "令牌放置") | [Go](../problems/bag-of-tokens) | Medium |
-| <span id="949">949</span> | [Largest Time for Given Digits](https://leetcode.com/problems/largest-time-for-given-digits "给定数字能组成的最大时间") | [Go](../problems/largest-time-for-given-digits) | Medium |
-| <span id="950">950</span> | [Reveal Cards In Increasing Order](https://leetcode.com/problems/reveal-cards-in-increasing-order "按递增顺序显示卡牌") | [Go](../problems/reveal-cards-in-increasing-order) | Medium |
-| <span id="951">951</span> | [Flip Equivalent Binary Trees](https://leetcode.com/problems/flip-equivalent-binary-trees "翻转等价二叉树") | [Go](../problems/flip-equivalent-binary-trees) | Medium |
-| <span id="952">952</span> | [Largest Component Size by Common Factor](https://leetcode.com/problems/largest-component-size-by-common-factor "按公因数计算最大组件大小") | [Go](../problems/largest-component-size-by-common-factor) | Hard |
-| <span id="953">953</span> | [Verifying an Alien Dictionary](https://leetcode.com/problems/verifying-an-alien-dictionary "验证外星语词典") | [Go](../problems/verifying-an-alien-dictionary) | Easy |
-| <span id="954">954</span> | [Array of Doubled Pairs](https://leetcode.com/problems/array-of-doubled-pairs "二倍数对数组") | [Go](../problems/array-of-doubled-pairs) | Medium |
-| <span id="955">955</span> | [Delete Columns to Make Sorted II](https://leetcode.com/problems/delete-columns-to-make-sorted-ii "删列造序 II") | [Go](../problems/delete-columns-to-make-sorted-ii) | Medium |
-| <span id="956">956</span> | [Tallest Billboard](https://leetcode.com/problems/tallest-billboard "最高的广告牌") | [Go](../problems/tallest-billboard) | Hard |
-| <span id="957">957</span> | [Prison Cells After N Days](https://leetcode.com/problems/prison-cells-after-n-days "N 天后的牢房") | [Go](../problems/prison-cells-after-n-days) | Medium |
-| <span id="958">958</span> | [Check Completeness of a Binary Tree](https://leetcode.com/problems/check-completeness-of-a-binary-tree "二叉树的完全性检验") | [Go](../problems/check-completeness-of-a-binary-tree) | Medium |
-| <span id="959">959</span> | [Regions Cut By Slashes](https://leetcode.com/problems/regions-cut-by-slashes "由斜杠划分区域") | [Go](../problems/regions-cut-by-slashes) | Medium |
-| <span id="960">960</span> | [Delete Columns to Make Sorted III](https://leetcode.com/problems/delete-columns-to-make-sorted-iii "删列造序 III") | [Go](../problems/delete-columns-to-make-sorted-iii) | Hard |
-| <span id="961">961</span> | [N-Repeated Element in Size 2N Array](https://leetcode.com/problems/n-repeated-element-in-size-2n-array "在长度 2N 的数组中找出重复 N 次的元素") | [Go](../problems/n-repeated-element-in-size-2n-array) | Easy |
-| <span id="962">962</span> | [Maximum Width Ramp](https://leetcode.com/problems/maximum-width-ramp "最大宽度坡") | [Go](../problems/maximum-width-ramp) | Medium |
-| <span id="963">963</span> | [Minimum Area Rectangle II](https://leetcode.com/problems/minimum-area-rectangle-ii "最小面积矩形 II") | [Go](../problems/minimum-area-rectangle-ii) | Medium |
-| <span id="964">964</span> | [Least Operators to Express Number](https://leetcode.com/problems/least-operators-to-express-number "表示数字的最少运算符") | [Go](../problems/least-operators-to-express-number) | Hard |
-| <span id="965">965</span> | [Univalued Binary Tree](https://leetcode.com/problems/univalued-binary-tree "单值二叉树") | [Go](../problems/univalued-binary-tree) | Easy |
-| <span id="966">966</span> | [Vowel Spellchecker](https://leetcode.com/problems/vowel-spellchecker "元音拼写检查器") | [Go](../problems/vowel-spellchecker) | Medium |
-| <span id="967">967</span> | [Numbers With Same Consecutive Differences](https://leetcode.com/problems/numbers-with-same-consecutive-differences "连续差相同的数字") | [Go](../problems/numbers-with-same-consecutive-differences) | Medium |
-| <span id="968">968</span> | [Binary Tree Cameras](https://leetcode.com/problems/binary-tree-cameras "监控二叉树") | [Go](../problems/binary-tree-cameras) | Hard |
-| <span id="969">969</span> | [Pancake Sorting](https://leetcode.com/problems/pancake-sorting "煎饼排序") | [Go](../problems/pancake-sorting) | Medium |
-| <span id="970">970</span> | [Powerful Integers](https://leetcode.com/problems/powerful-integers "强整数") | [Go](../problems/powerful-integers) | Medium |
-| <span id="971">971</span> | [Flip Binary Tree To Match Preorder Traversal](https://leetcode.com/problems/flip-binary-tree-to-match-preorder-traversal "翻转二叉树以匹配先序遍历") | [Go](../problems/flip-binary-tree-to-match-preorder-traversal) | Medium |
-| <span id="972">972</span> | [Equal Rational Numbers](https://leetcode.com/problems/equal-rational-numbers "相等的有理数") | [Go](../problems/equal-rational-numbers) | Hard |
-| <span id="973">973</span> | [K Closest Points to Origin](https://leetcode.com/problems/k-closest-points-to-origin "最接近原点的 K 个点") | [Go](../problems/k-closest-points-to-origin) | Medium |
-| <span id="974">974</span> | [Subarray Sums Divisible by K](https://leetcode.com/problems/subarray-sums-divisible-by-k "和可被 K 整除的子数组") | [Go](../problems/subarray-sums-divisible-by-k) | Medium |
-| <span id="975">975</span> | [Odd Even Jump](https://leetcode.com/problems/odd-even-jump "奇偶跳") | [Go](../problems/odd-even-jump) | Hard |
-| <span id="976">976</span> | [Largest Perimeter Triangle](https://leetcode.com/problems/largest-perimeter-triangle "三角形的最大周长") | [Go](../problems/largest-perimeter-triangle) | Easy |
-| <span id="977">977</span> | [Squares of a Sorted Array](https://leetcode.com/problems/squares-of-a-sorted-array "有序数组的平方") | [Go](../problems/squares-of-a-sorted-array) | Easy |
-| <span id="978">978</span> | [Longest Turbulent Subarray](https://leetcode.com/problems/longest-turbulent-subarray "最长湍流子数组") | [Go](../problems/longest-turbulent-subarray) | Medium |
-| <span id="979">979</span> | [Distribute Coins in Binary Tree](https://leetcode.com/problems/distribute-coins-in-binary-tree "在二叉树中分配硬币") | [Go](../problems/distribute-coins-in-binary-tree) | Medium |
-| <span id="980">980</span> | [Unique Paths III](https://leetcode.com/problems/unique-paths-iii "不同路径 III") | [Go](../problems/unique-paths-iii) | Hard |
-| <span id="981">981</span> | [Time Based Key-Value Store](https://leetcode.com/problems/time-based-key-value-store "基于时间的键值存储") | [Go](../problems/time-based-key-value-store) | Medium |
-| <span id="982">982</span> | [Triples with Bitwise AND Equal To Zero](https://leetcode.com/problems/triples-with-bitwise-and-equal-to-zero "按位与为零的三元组") | [Go](../problems/triples-with-bitwise-and-equal-to-zero) | Hard |
-| <span id="983">983</span> | [Minimum Cost For Tickets](https://leetcode.com/problems/minimum-cost-for-tickets "最低票价") | [Go](../problems/minimum-cost-for-tickets) | Medium |
-| <span id="984">984</span> | [String Without AAA or BBB](https://leetcode.com/problems/string-without-aaa-or-bbb "不含 AAA 或 BBB 的字符串") | [Go](../problems/string-without-aaa-or-bbb) | Medium |
-| <span id="985">985</span> | [Sum of Even Numbers After Queries](https://leetcode.com/problems/sum-of-even-numbers-after-queries "查询后的偶数和") | [Go](../problems/sum-of-even-numbers-after-queries) | Medium |
-| <span id="986">986</span> | [Interval List Intersections](https://leetcode.com/problems/interval-list-intersections "区间列表的交集") | [Go](../problems/interval-list-intersections) | Medium |
-| <span id="987">987</span> | [Vertical Order Traversal of a Binary Tree](https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree "二叉树的垂序遍历") | [Go](../problems/vertical-order-traversal-of-a-binary-tree) | Hard |
-| <span id="988">988</span> | [Smallest String Starting From Leaf](https://leetcode.com/problems/smallest-string-starting-from-leaf "从叶结点开始的最小字符串") | [Go](../problems/smallest-string-starting-from-leaf) | Medium |
-| <span id="989">989</span> | [Add to Array-Form of Integer](https://leetcode.com/problems/add-to-array-form-of-integer "数组形式的整数加法") | [Go](../problems/add-to-array-form-of-integer) | Easy |
-| <span id="990">990</span> | [Satisfiability of Equality Equations](https://leetcode.com/problems/satisfiability-of-equality-equations "等式方程的可满足性") | [Go](../problems/satisfiability-of-equality-equations) | Medium |
-| <span id="991">991</span> | [Broken Calculator](https://leetcode.com/problems/broken-calculator "坏了的计算器") | [Go](../problems/broken-calculator) | Medium |
-| <span id="992">992</span> | [Subarrays with K Different Integers](https://leetcode.com/problems/subarrays-with-k-different-integers "K 个不同整数的子数组") | [Go](../problems/subarrays-with-k-different-integers) | Hard |
-| <span id="993">993</span> | [Cousins in Binary Tree](https://leetcode.com/problems/cousins-in-binary-tree "二叉树的堂兄弟节点") | [Go](../problems/cousins-in-binary-tree) | Easy |
-| <span id="994">994</span> | [Rotting Oranges](https://leetcode.com/problems/rotting-oranges "腐烂的橘子") | [Go](../problems/rotting-oranges) | Medium |
-| <span id="995">995</span> | [Minimum Number of K Consecutive Bit Flips](https://leetcode.com/problems/minimum-number-of-k-consecutive-bit-flips "K 连续位的最小翻转次数") | [Go](../problems/minimum-number-of-k-consecutive-bit-flips) | Hard |
-| <span id="996">996</span> | [Number of Squareful Arrays](https://leetcode.com/problems/number-of-squareful-arrays "正方形数组的数目") | [Go](../problems/number-of-squareful-arrays) | Hard |
-| <span id="997">997</span> | [Find the Town Judge](https://leetcode.com/problems/find-the-town-judge "找到小镇的法官") | [Go](../problems/find-the-town-judge) | Easy |
-| <span id="998">998</span> | [Maximum Binary Tree II](https://leetcode.com/problems/maximum-binary-tree-ii "最大二叉树 II") | [Go](../problems/maximum-binary-tree-ii) | Medium |
-| <span id="999">999</span> | [Available Captures for Rook](https://leetcode.com/problems/available-captures-for-rook "可以被一步捕获的棋子数") | [Go](../problems/available-captures-for-rook) | Easy |
-| <span id="1000">1000</span> | [Minimum Cost to Merge Stones](https://leetcode.com/problems/minimum-cost-to-merge-stones "合并石头的最低成本") | [Go](../problems/minimum-cost-to-merge-stones) | Hard |
-| <span id="1001">1001</span> | [Grid Illumination](https://leetcode.com/problems/grid-illumination "网格照明") | [Go](../problems/grid-illumination) | Hard |
-| <span id="1002">1002</span> | [Find Common Characters](https://leetcode.com/problems/find-common-characters "查找共用字符") | [Go](../problems/find-common-characters) | Easy |
-| <span id="1003">1003</span> | [Check If Word Is Valid After Substitutions](https://leetcode.com/problems/check-if-word-is-valid-after-substitutions "检查替换后的词是否有效") | [Go](../problems/check-if-word-is-valid-after-substitutions) | Medium |
-| <span id="1004">1004</span> | [Max Consecutive Ones III](https://leetcode.com/problems/max-consecutive-ones-iii "最大连续1的个数 III") | [Go](../problems/max-consecutive-ones-iii) | Medium |
-| <span id="1005">1005</span> | [Maximize Sum Of Array After K Negations](https://leetcode.com/problems/maximize-sum-of-array-after-k-negations "K 次取反后最大化的数组和") | [Go](../problems/maximize-sum-of-array-after-k-negations) | Easy |
-| <span id="1006">1006</span> | [Clumsy Factorial](https://leetcode.com/problems/clumsy-factorial "笨阶乘") | [Go](../problems/clumsy-factorial) | Medium |
-| <span id="1007">1007</span> | [Minimum Domino Rotations For Equal Row](https://leetcode.com/problems/minimum-domino-rotations-for-equal-row "行相等的最少多米诺旋转") | [Go](../problems/minimum-domino-rotations-for-equal-row) | Medium |
-| <span id="1008">1008</span> | [Construct Binary Search Tree from Preorder Traversal](https://leetcode.com/problems/construct-binary-search-tree-from-preorder-traversal "前序遍历构造二叉搜索树") | [Go](../problems/construct-binary-search-tree-from-preorder-traversal) | Medium |
-| <span id="1009">1009</span> | [Complement of Base 10 Integer](https://leetcode.com/problems/complement-of-base-10-integer "十进制整数的反码") | [Go](../problems/complement-of-base-10-integer) | Easy |
-| <span id="1010">1010</span> | [Pairs of Songs With Total Durations Divisible by 60](https://leetcode.com/problems/pairs-of-songs-with-total-durations-divisible-by-60 "总持续时间可被 60 整除的歌曲") | [Go](../problems/pairs-of-songs-with-total-durations-divisible-by-60) | Medium |
-| <span id="1011">1011</span> | [Capacity To Ship Packages Within D Days](https://leetcode.com/problems/capacity-to-ship-packages-within-d-days "在 D 天内送达包裹的能力") | [Go](../problems/capacity-to-ship-packages-within-d-days) | Medium |
-| <span id="1012">1012</span> | [Numbers With Repeated Digits](https://leetcode.com/problems/numbers-with-repeated-digits "至少有 1 位重复的数字") | [Go](../problems/numbers-with-repeated-digits) | Hard |
-| <span id="1013">1013</span> | [Partition Array Into Three Parts With Equal Sum](https://leetcode.com/problems/partition-array-into-three-parts-with-equal-sum "将数组分成和相等的三个部分") | [Go](../problems/partition-array-into-three-parts-with-equal-sum) | Easy |
-| <span id="1014">1014</span> | [Best Sightseeing Pair](https://leetcode.com/problems/best-sightseeing-pair "最佳观光组合") | [Go](../problems/best-sightseeing-pair) | Medium |
-| <span id="1015">1015</span> | [Smallest Integer Divisible by K](https://leetcode.com/problems/smallest-integer-divisible-by-k "可被 K 整除的最小整数") | [Go](../problems/smallest-integer-divisible-by-k) | Medium |
-| <span id="1016">1016</span> | [Binary String With Substrings Representing 1 To N](https://leetcode.com/problems/binary-string-with-substrings-representing-1-to-n "子串能表示从 1 到 N 数字的二进制串") | [Go](../problems/binary-string-with-substrings-representing-1-to-n) | Medium |
-| <span id="1017">1017</span> | [Convert to Base -2](https://leetcode.com/problems/convert-to-base-2 "负二进制转换") | [Go](../problems/convert-to-base-2) | Medium |
-| <span id="1018">1018</span> | [Binary Prefix Divisible By 5](https://leetcode.com/problems/binary-prefix-divisible-by-5 "可被 5 整除的二进制前缀") | [Go](../problems/binary-prefix-divisible-by-5) | Easy |
-| <span id="1019">1019</span> | [Next Greater Node In Linked List](https://leetcode.com/problems/next-greater-node-in-linked-list "链表中的下一个更大节点") | [Go](../problems/next-greater-node-in-linked-list) | Medium |
-| <span id="1020">1020</span> | [Number of Enclaves](https://leetcode.com/problems/number-of-enclaves "飞地的数量") | [Go](../problems/number-of-enclaves) | Medium |
-| <span id="1021">1021</span> | [Remove Outermost Parentheses](https://leetcode.com/problems/remove-outermost-parentheses "删除最外层的括号") | [Go](../problems/remove-outermost-parentheses) | Easy |
-| <span id="1022">1022</span> | [Sum of Root To Leaf Binary Numbers](https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers "从根到叶的二进制数之和") | [Go](../problems/sum-of-root-to-leaf-binary-numbers) | Easy |
-| <span id="1023">1023</span> | [Camelcase Matching](https://leetcode.com/problems/camelcase-matching "驼峰式匹配") | [Go](../problems/camelcase-matching) | Medium |
-| <span id="1024">1024</span> | [Video Stitching](https://leetcode.com/problems/video-stitching "视频拼接") | [Go](../problems/video-stitching) | Medium |
-| <span id="1025">1025</span> | [Divisor Game](https://leetcode.com/problems/divisor-game "除数博弈") | [Go](../problems/divisor-game) | Easy |
-| <span id="1026">1026</span> | [Maximum Difference Between Node and Ancestor](https://leetcode.com/problems/maximum-difference-between-node-and-ancestor "节点与其祖先之间的最大差值") | [Go](../problems/maximum-difference-between-node-and-ancestor) | Medium |
-| <span id="1027">1027</span> | [Longest Arithmetic Subsequence](https://leetcode.com/problems/longest-arithmetic-subsequence "最长等差数列") | [Go](../problems/longest-arithmetic-subsequence) | Medium |
-| <span id="1028">1028</span> | [Recover a Tree From Preorder Traversal](https://leetcode.com/problems/recover-a-tree-from-preorder-traversal "从先序遍历还原二叉树") | [Go](../problems/recover-a-tree-from-preorder-traversal) | Hard |
-| <span id="1029">1029</span> | [Two City Scheduling](https://leetcode.com/problems/two-city-scheduling "两地调度") | [Go](../problems/two-city-scheduling) | Medium |
-| <span id="1030">1030</span> | [Matrix Cells in Distance Order](https://leetcode.com/problems/matrix-cells-in-distance-order "距离顺序排列矩阵单元格") | [Go](../problems/matrix-cells-in-distance-order) | Easy |
-| <span id="1031">1031</span> | [Maximum Sum of Two Non-Overlapping Subarrays](https://leetcode.com/problems/maximum-sum-of-two-non-overlapping-subarrays "两个非重叠子数组的最大和") | [Go](../problems/maximum-sum-of-two-non-overlapping-subarrays) | Medium |
-| <span id="1032">1032</span> | [Stream of Characters](https://leetcode.com/problems/stream-of-characters "字符流") | [Go](../problems/stream-of-characters) | Hard |
-| <span id="1033">1033</span> | [Moving Stones Until Consecutive](https://leetcode.com/problems/moving-stones-until-consecutive "移动石子直到连续") | [Go](../problems/moving-stones-until-consecutive) | Medium |
-| <span id="1034">1034</span> | [Coloring A Border](https://leetcode.com/problems/coloring-a-border "边界着色") | [Go](../problems/coloring-a-border) | Medium |
-| <span id="1035">1035</span> | [Uncrossed Lines](https://leetcode.com/problems/uncrossed-lines "不相交的线") | [Go](../problems/uncrossed-lines) | Medium |
-| <span id="1036">1036</span> | [Escape a Large Maze](https://leetcode.com/problems/escape-a-large-maze "逃离大迷宫") | [Go](../problems/escape-a-large-maze) | Hard |
-| <span id="1037">1037</span> | [Valid Boomerang](https://leetcode.com/problems/valid-boomerang "有效的回旋镖") | [Go](../problems/valid-boomerang) | Easy |
-| <span id="1038">1038</span> | [Binary Search Tree to Greater Sum Tree](https://leetcode.com/problems/binary-search-tree-to-greater-sum-tree "把二叉搜索树转换为累加树") | [Go](../problems/binary-search-tree-to-greater-sum-tree) | Medium |
-| <span id="1039">1039</span> | [Minimum Score Triangulation of Polygon](https://leetcode.com/problems/minimum-score-triangulation-of-polygon "多边形三角剖分的最低得分") | [Go](../problems/minimum-score-triangulation-of-polygon) | Medium |
-| <span id="1040">1040</span> | [Moving Stones Until Consecutive II](https://leetcode.com/problems/moving-stones-until-consecutive-ii "移动石子直到连续 II") | [Go](../problems/moving-stones-until-consecutive-ii) | Medium |
-| <span id="1041">1041</span> | [Robot Bounded In Circle](https://leetcode.com/problems/robot-bounded-in-circle "困于环中的机器人") | [Go](../problems/robot-bounded-in-circle) | Medium |
-| <span id="1042">1042</span> | [Flower Planting With No Adjacent](https://leetcode.com/problems/flower-planting-with-no-adjacent "不邻接植花") | [Go](../problems/flower-planting-with-no-adjacent) | Medium |
-| <span id="1043">1043</span> | [Partition Array for Maximum Sum](https://leetcode.com/problems/partition-array-for-maximum-sum "分隔数组以得到最大和") | [Go](../problems/partition-array-for-maximum-sum) | Medium |
-| <span id="1044">1044</span> | [Longest Duplicate Substring](https://leetcode.com/problems/longest-duplicate-substring "最长重复子串") | [Go](../problems/longest-duplicate-substring) | Hard |
-| <span id="1045">1045</span> | [Customers Who Bought All Products](https://leetcode.com/problems/customers-who-bought-all-products "买下所有产品的客户") 🔒 | [MySQL](../problems/customers-who-bought-all-products) | Medium |
-| <span id="1046">1046</span> | [Last Stone Weight](https://leetcode.com/problems/last-stone-weight "最后一块石头的重量") | [Go](../problems/last-stone-weight) | Easy |
-| <span id="1047">1047</span> | [Remove All Adjacent Duplicates In String](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string "删除字符串中的所有相邻重复项") | [Go](../problems/remove-all-adjacent-duplicates-in-string) | Easy |
-| <span id="1048">1048</span> | [Longest String Chain](https://leetcode.com/problems/longest-string-chain "最长字符串链") | [Go](../problems/longest-string-chain) | Medium |
-| <span id="1049">1049</span> | [Last Stone Weight II](https://leetcode.com/problems/last-stone-weight-ii "最后一块石头的重量 II") | [Go](../problems/last-stone-weight-ii) | Medium |
-| <span id="1050">1050</span> | [Actors and Directors Who Cooperated At Least Three Times](https://leetcode.com/problems/actors-and-directors-who-cooperated-at-least-three-times "合作过至少三次的演员和导演") 🔒 | [MySQL](../problems/actors-and-directors-who-cooperated-at-least-three-times) | Easy |
-| <span id="1051">1051</span> | [Height Checker](https://leetcode.com/problems/height-checker "高度检查器") | [Go](../problems/height-checker) | Easy |
-| <span id="1052">1052</span> | [Grumpy Bookstore Owner](https://leetcode.com/problems/grumpy-bookstore-owner "爱生气的书店老板") | [Go](../problems/grumpy-bookstore-owner) | Medium |
-| <span id="1053">1053</span> | [Previous Permutation With One Swap](https://leetcode.com/problems/previous-permutation-with-one-swap "交换一次的先前排列") | [Go](../problems/previous-permutation-with-one-swap) | Medium |
-| <span id="1054">1054</span> | [Distant Barcodes](https://leetcode.com/problems/distant-barcodes "距离相等的条形码") | [Go](../problems/distant-barcodes) | Medium |
-| <span id="1055">1055</span> | [Shortest Way to Form String](https://leetcode.com/problems/shortest-way-to-form-string "形成字符串的最短路径") 🔒 | [Go](../problems/shortest-way-to-form-string) | Medium |
-| <span id="1056">1056</span> | [Confusing Number](https://leetcode.com/problems/confusing-number "易混淆数") 🔒 | [Go](../problems/confusing-number) | Easy |
-| <span id="1057">1057</span> | [Campus Bikes](https://leetcode.com/problems/campus-bikes "校园自行车分配") 🔒 | [Go](../problems/campus-bikes) | Medium |
-| <span id="1058">1058</span> | [Minimize Rounding Error to Meet Target](https://leetcode.com/problems/minimize-rounding-error-to-meet-target "最小化舍入误差以满足目标") 🔒 | [Go](../problems/minimize-rounding-error-to-meet-target) | Medium |
-| <span id="1059">1059</span> | [All Paths from Source Lead to Destination](https://leetcode.com/problems/all-paths-from-source-lead-to-destination "从始点到终点的所有路径") 🔒 | [Go](../problems/all-paths-from-source-lead-to-destination) | Medium |
-| <span id="1060">1060</span> | [Missing Element in Sorted Array](https://leetcode.com/problems/missing-element-in-sorted-array "有序数组中的缺失元素") 🔒 | [Go](../problems/missing-element-in-sorted-array) | Medium |
-| <span id="1061">1061</span> | [Lexicographically Smallest Equivalent String](https://leetcode.com/problems/lexicographically-smallest-equivalent-string "按字典序排列最小的等效字符串") 🔒 | [Go](../problems/lexicographically-smallest-equivalent-string) | Medium |
-| <span id="1062">1062</span> | [Longest Repeating Substring](https://leetcode.com/problems/longest-repeating-substring "最长重复子串") 🔒 | [Go](../problems/longest-repeating-substring) | Medium |
-| <span id="1063">1063</span> | [Number of Valid Subarrays](https://leetcode.com/problems/number-of-valid-subarrays "有效子数组的数目") 🔒 | [Go](../problems/number-of-valid-subarrays) | Hard |
-| <span id="1064">1064</span> | [Fixed Point](https://leetcode.com/problems/fixed-point "不动点") 🔒 | [Go](../problems/fixed-point) | Easy |
-| <span id="1065">1065</span> | [Index Pairs of a String](https://leetcode.com/problems/index-pairs-of-a-string "字符串的索引对") 🔒 | [Go](../problems/index-pairs-of-a-string) | Easy |
-| <span id="1066">1066</span> | [Campus Bikes II](https://leetcode.com/problems/campus-bikes-ii "校园自行车分配 II") 🔒 | [Go](../problems/campus-bikes-ii) | Medium |
-| <span id="1067">1067</span> | [Digit Count in Range](https://leetcode.com/problems/digit-count-in-range "范围内的数字计数") 🔒 | [Go](../problems/digit-count-in-range) | Hard |
-| <span id="1068">1068</span> | [Product Sales Analysis I](https://leetcode.com/problems/product-sales-analysis-i "产品销售分析 I") 🔒 | [MySQL](../problems/product-sales-analysis-i) | Easy |
-| <span id="1069">1069</span> | [Product Sales Analysis II](https://leetcode.com/problems/product-sales-analysis-ii "产品销售分析 II") 🔒 | [MySQL](../problems/product-sales-analysis-ii) | Easy |
-| <span id="1070">1070</span> | [Product Sales Analysis III](https://leetcode.com/problems/product-sales-analysis-iii "产品销售分析 III") 🔒 | [MySQL](../problems/product-sales-analysis-iii) | Medium |
-| <span id="1071">1071</span> | [Greatest Common Divisor of Strings](https://leetcode.com/problems/greatest-common-divisor-of-strings "字符串的最大公因子") | [Go](../problems/greatest-common-divisor-of-strings) | Easy |
-| <span id="1072">1072</span> | [Flip Columns For Maximum Number of Equal Rows](https://leetcode.com/problems/flip-columns-for-maximum-number-of-equal-rows "按列翻转得到最大值等行数") | [Go](../problems/flip-columns-for-maximum-number-of-equal-rows) | Medium |
-| <span id="1073">1073</span> | [Adding Two Negabinary Numbers](https://leetcode.com/problems/adding-two-negabinary-numbers "负二进制数相加") | [Go](../problems/adding-two-negabinary-numbers) | Medium |
-| <span id="1074">1074</span> | [Number of Submatrices That Sum to Target](https://leetcode.com/problems/number-of-submatrices-that-sum-to-target "元素和为目标值的子矩阵数量") | [Go](../problems/number-of-submatrices-that-sum-to-target) | Hard |
-| <span id="1075">1075</span> | [Project Employees I](https://leetcode.com/problems/project-employees-i "项目员工 I") 🔒 | [MySQL](../problems/project-employees-i) | Easy |
-| <span id="1076">1076</span> | [Project Employees II](https://leetcode.com/problems/project-employees-ii "项目员工II") 🔒 | [MySQL](../problems/project-employees-ii) | Easy |
-| <span id="1077">1077</span> | [Project Employees III](https://leetcode.com/problems/project-employees-iii "项目员工 III") 🔒 | [MySQL](../problems/project-employees-iii) | Medium |
-| <span id="1078">1078</span> | [Occurrences After Bigram](https://leetcode.com/problems/occurrences-after-bigram "Bigram 分词") | [Go](../problems/occurrences-after-bigram) | Easy |
-| <span id="1079">1079</span> | [Letter Tile Possibilities](https://leetcode.com/problems/letter-tile-possibilities "活字印刷") | [Go](../problems/letter-tile-possibilities) | Medium |
-| <span id="1080">1080</span> | [Insufficient Nodes in Root to Leaf Paths](https://leetcode.com/problems/insufficient-nodes-in-root-to-leaf-paths "根到叶路径上的不足节点") | [Go](../problems/insufficient-nodes-in-root-to-leaf-paths) | Medium |
-| <span id="1081">1081</span> | [Smallest Subsequence of Distinct Characters](https://leetcode.com/problems/smallest-subsequence-of-distinct-characters "不同字符的最小子序列") | [Go](../problems/smallest-subsequence-of-distinct-characters) | Medium |
-| <span id="1082">1082</span> | [Sales Analysis I](https://leetcode.com/problems/sales-analysis-i "销售分析 I ") 🔒 | [MySQL](../problems/sales-analysis-i) | Easy |
-| <span id="1083">1083</span> | [Sales Analysis II](https://leetcode.com/problems/sales-analysis-ii "销售分析 II") 🔒 | [MySQL](../problems/sales-analysis-ii) | Easy |
-| <span id="1084">1084</span> | [Sales Analysis III](https://leetcode.com/problems/sales-analysis-iii "销售分析III") 🔒 | [MySQL](../problems/sales-analysis-iii) | Easy |
-| <span id="1085">1085</span> | [Sum of Digits in the Minimum Number](https://leetcode.com/problems/sum-of-digits-in-the-minimum-number "最小元素各数位之和") 🔒 | [Go](../problems/sum-of-digits-in-the-minimum-number) | Easy |
-| <span id="1086">1086</span> | [High Five](https://leetcode.com/problems/high-five "前五科的均分") 🔒 | [Go](../problems/high-five) | Easy |
-| <span id="1087">1087</span> | [Brace Expansion](https://leetcode.com/problems/brace-expansion "花括号展开") 🔒 | [Go](../problems/brace-expansion) | Medium |
-| <span id="1088">1088</span> | [Confusing Number II](https://leetcode.com/problems/confusing-number-ii "易混淆数 II") 🔒 | [Go](../problems/confusing-number-ii) | Hard |
-| <span id="1089">1089</span> | [Duplicate Zeros](https://leetcode.com/problems/duplicate-zeros "复写零") | [Go](../problems/duplicate-zeros) | Easy |
-| <span id="1090">1090</span> | [Largest Values From Labels](https://leetcode.com/problems/largest-values-from-labels "受标签影响的最大值") | [Go](../problems/largest-values-from-labels) | Medium |
-| <span id="1091">1091</span> | [Shortest Path in Binary Matrix](https://leetcode.com/problems/shortest-path-in-binary-matrix "二进制矩阵中的最短路径") | [Go](../problems/shortest-path-in-binary-matrix) | Medium |
-| <span id="1092">1092</span> | [Shortest Common Supersequence](https://leetcode.com/problems/shortest-common-supersequence "最短公共超序列") | [Go](../problems/shortest-common-supersequence) | Hard |
-| <span id="1093">1093</span> | [Statistics from a Large Sample](https://leetcode.com/problems/statistics-from-a-large-sample "大样本统计") | [Go](../problems/statistics-from-a-large-sample) | Medium |
-| <span id="1094">1094</span> | [Car Pooling](https://leetcode.com/problems/car-pooling "拼车") | [Go](../problems/car-pooling) | Medium |
-| <span id="1095">1095</span> | [Find in Mountain Array](https://leetcode.com/problems/find-in-mountain-array "山脉数组中查找目标值") | [Go](../problems/find-in-mountain-array) | Hard |
-| <span id="1096">1096</span> | [Brace Expansion II](https://leetcode.com/problems/brace-expansion-ii "花括号展开 II") | [Go](../problems/brace-expansion-ii) | Hard |
-| <span id="1097">1097</span> | [Game Play Analysis V](https://leetcode.com/problems/game-play-analysis-v "游戏玩法分析 V") 🔒 | [MySQL](../problems/game-play-analysis-v) | Hard |
-| <span id="1098">1098</span> | [Unpopular Books](https://leetcode.com/problems/unpopular-books "小众书籍") 🔒 | [MySQL](../problems/unpopular-books) | Medium |
-| <span id="1099">1099</span> | [Two Sum Less Than K](https://leetcode.com/problems/two-sum-less-than-k "小于 K 的两数之和") 🔒 | [Go](../problems/two-sum-less-than-k) | Easy |
-| <span id="1100">1100</span> | [Find K-Length Substrings With No Repeated Characters](https://leetcode.com/problems/find-k-length-substrings-with-no-repeated-characters "长度为 K 的无重复字符子串") 🔒 | [Go](../problems/find-k-length-substrings-with-no-repeated-characters) | Medium |
-| <span id="1101">1101</span> | [The Earliest Moment When Everyone Become Friends](https://leetcode.com/problems/the-earliest-moment-when-everyone-become-friends "彼此熟识的最早时间") 🔒 | [Go](../problems/the-earliest-moment-when-everyone-become-friends) | Medium |
-| <span id="1102">1102</span> | [Path With Maximum Minimum Value](https://leetcode.com/problems/path-with-maximum-minimum-value "得分最高的路径") 🔒 | [Go](../problems/path-with-maximum-minimum-value) | Medium |
-| <span id="1103">1103</span> | [Distribute Candies to People](https://leetcode.com/problems/distribute-candies-to-people "分糖果 II") | [Go](../problems/distribute-candies-to-people) | Easy |
-| <span id="1104">1104</span> | [Path In Zigzag Labelled Binary Tree](https://leetcode.com/problems/path-in-zigzag-labelled-binary-tree "二叉树寻路") | [Go](../problems/path-in-zigzag-labelled-binary-tree) | Medium |
-| <span id="1105">1105</span> | [Filling Bookcase Shelves](https://leetcode.com/problems/filling-bookcase-shelves "填充书架") | [Go](../problems/filling-bookcase-shelves) | Medium |
-| <span id="1106">1106</span> | [Parsing A Boolean Expression](https://leetcode.com/problems/parsing-a-boolean-expression "解析布尔表达式") | [Go](../problems/parsing-a-boolean-expression) | Hard |
-| <span id="1107">1107</span> | [New Users Daily Count](https://leetcode.com/problems/new-users-daily-count "每日新用户统计") 🔒 | [MySQL](../problems/new-users-daily-count) | Medium |
-| <span id="1108">1108</span> | [Defanging an IP Address](https://leetcode.com/problems/defanging-an-ip-address "IP 地址无效化") | [Go](../problems/defanging-an-ip-address) | Easy |
-| <span id="1109">1109</span> | [Corporate Flight Bookings](https://leetcode.com/problems/corporate-flight-bookings "航班预订统计") | [Go](../problems/corporate-flight-bookings) | Medium |
-| <span id="1110">1110</span> | [Delete Nodes And Return Forest](https://leetcode.com/problems/delete-nodes-and-return-forest "删点成林") | [Go](../problems/delete-nodes-and-return-forest) | Medium |
-| <span id="1111">1111</span> | [Maximum Nesting Depth of Two Valid Parentheses Strings](https://leetcode.com/problems/maximum-nesting-depth-of-two-valid-parentheses-strings "有效括号的嵌套深度") | [Go](../problems/maximum-nesting-depth-of-two-valid-parentheses-strings) | Medium |
-| <span id="1112">1112</span> | [Highest Grade For Each Student](https://leetcode.com/problems/highest-grade-for-each-student "每位学生的最高成绩") 🔒 | [MySQL](../problems/highest-grade-for-each-student) | Medium |
-| <span id="1113">1113</span> | [Reported Posts](https://leetcode.com/problems/reported-posts "报告的记录") 🔒 | [MySQL](../problems/reported-posts) | Easy |
-| <span id="1114">1114</span> | [Print in Order](https://leetcode.com/problems/print-in-order "按序打印") | [Go](../problems/print-in-order) | Easy |
-| <span id="1115">1115</span> | [Print FooBar Alternately](https://leetcode.com/problems/print-foobar-alternately "交替打印 FooBar") | [Go](../problems/print-foobar-alternately) | Medium |
-| <span id="1116">1116</span> | [Print Zero Even Odd](https://leetcode.com/problems/print-zero-even-odd "打印零与奇偶数") | [Go](../problems/print-zero-even-odd) | Medium |
-| <span id="1117">1117</span> | [Building H2O](https://leetcode.com/problems/building-h2o "H2O 生成") | [Go](../problems/building-h2o) | Medium |
-| <span id="1118">1118</span> | [Number of Days in a Month](https://leetcode.com/problems/number-of-days-in-a-month "一月有多少天") 🔒 | [Go](../problems/number-of-days-in-a-month) | Easy |
-| <span id="1119">1119</span> | [Remove Vowels from a String](https://leetcode.com/problems/remove-vowels-from-a-string "删去字符串中的元音") 🔒 | [Go](../problems/remove-vowels-from-a-string) | Easy |
-| <span id="1120">1120</span> | [Maximum Average Subtree](https://leetcode.com/problems/maximum-average-subtree "子树的最大平均值") 🔒 | [Go](../problems/maximum-average-subtree) | Medium |
-| <span id="1121">1121</span> | [Divide Array Into Increasing Sequences](https://leetcode.com/problems/divide-array-into-increasing-sequences "将数组分成几个递增序列") 🔒 | [Go](../problems/divide-array-into-increasing-sequences) | Hard |
-| <span id="1122">1122</span> | [Relative Sort Array](https://leetcode.com/problems/relative-sort-array "数组的相对排序") | [Go](../problems/relative-sort-array) | Easy |
-| <span id="1123">1123</span> | [Lowest Common Ancestor of Deepest Leaves](https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves "最深叶节点的最近公共祖先") | [Go](../problems/lowest-common-ancestor-of-deepest-leaves) | Medium |
-| <span id="1124">1124</span> | [Longest Well-Performing Interval](https://leetcode.com/problems/longest-well-performing-interval "表现良好的最长时间段") | [Go](../problems/longest-well-performing-interval) | Medium |
-| <span id="1125">1125</span> | [Smallest Sufficient Team](https://leetcode.com/problems/smallest-sufficient-team "最小的必要团队") | [Go](../problems/smallest-sufficient-team) | Hard |
-| <span id="1126">1126</span> | [Active Businesses](https://leetcode.com/problems/active-businesses "查询活跃业务") 🔒 | [MySQL](../problems/active-businesses) | Medium |
-| <span id="1127">1127</span> | [User Purchase Platform](https://leetcode.com/problems/user-purchase-platform "用户购买平台") 🔒 | [MySQL](../problems/user-purchase-platform) | Hard |
-| <span id="1128">1128</span> | [Number of Equivalent Domino Pairs](https://leetcode.com/problems/number-of-equivalent-domino-pairs "等价多米诺骨牌对的数量") | [Go](../problems/number-of-equivalent-domino-pairs) | Easy |
-| <span id="1129">1129</span> | [Shortest Path with Alternating Colors](https://leetcode.com/problems/shortest-path-with-alternating-colors "颜色交替的最短路径") | [Go](../problems/shortest-path-with-alternating-colors) | Medium |
-| <span id="1130">1130</span> | [Minimum Cost Tree From Leaf Values](https://leetcode.com/problems/minimum-cost-tree-from-leaf-values "叶值的最小代价生成树") | [Go](../problems/minimum-cost-tree-from-leaf-values) | Medium |
-| <span id="1131">1131</span> | [Maximum of Absolute Value Expression](https://leetcode.com/problems/maximum-of-absolute-value-expression "绝对值表达式的最大值") | [Go](../problems/maximum-of-absolute-value-expression) | Medium |
-| <span id="1132">1132</span> | [Reported Posts II](https://leetcode.com/problems/reported-posts-ii "报告的记录 II") 🔒 | [MySQL](../problems/reported-posts-ii) | Medium |
-| <span id="1133">1133</span> | [Largest Unique Number](https://leetcode.com/problems/largest-unique-number "最大唯一数") 🔒 | [Go](../problems/largest-unique-number) | Easy |
-| <span id="1134">1134</span> | [Armstrong Number](https://leetcode.com/problems/armstrong-number "阿姆斯特朗数") 🔒 | [Go](../problems/armstrong-number) | Easy |
-| <span id="1135">1135</span> | [Connecting Cities With Minimum Cost](https://leetcode.com/problems/connecting-cities-with-minimum-cost "最低成本联通所有城市") 🔒 | [Go](../problems/connecting-cities-with-minimum-cost) | Medium |
-| <span id="1136">1136</span> | [Parallel Courses](https://leetcode.com/problems/parallel-courses "平行课程") 🔒 | [Go](../problems/parallel-courses) | Medium |
-| <span id="1137">1137</span> | [N-th Tribonacci Number](https://leetcode.com/problems/n-th-tribonacci-number "第 N 个泰波那契数") | [Go](../problems/n-th-tribonacci-number) | Easy |
-| <span id="1138">1138</span> | [Alphabet Board Path](https://leetcode.com/problems/alphabet-board-path "字母板上的路径") | [Go](../problems/alphabet-board-path) | Medium |
-| <span id="1139">1139</span> | [Largest 1-Bordered Square](https://leetcode.com/problems/largest-1-bordered-square "最大的以 1 为边界的正方形") | [Go](../problems/largest-1-bordered-square) | Medium |
-| <span id="1140">1140</span> | [Stone Game II](https://leetcode.com/problems/stone-game-ii "石子游戏 II") | [Go](../problems/stone-game-ii) | Medium |
-| <span id="1141">1141</span> | [User Activity for the Past 30 Days I](https://leetcode.com/problems/user-activity-for-the-past-30-days-i "查询近30天活跃用户数") 🔒 | [MySQL](../problems/user-activity-for-the-past-30-days-i) | Easy |
-| <span id="1142">1142</span> | [User Activity for the Past 30 Days II](https://leetcode.com/problems/user-activity-for-the-past-30-days-ii "过去30天的用户活动 II") 🔒 | [MySQL](../problems/user-activity-for-the-past-30-days-ii) | Easy |
-| <span id="1143">1143</span> | [Longest Common Subsequence](https://leetcode.com/problems/longest-common-subsequence "最长公共子序列") | [Go](../problems/longest-common-subsequence) | Medium |
-| <span id="1144">1144</span> | [Decrease Elements To Make Array Zigzag](https://leetcode.com/problems/decrease-elements-to-make-array-zigzag "递减元素使数组呈锯齿状") | [Go](../problems/decrease-elements-to-make-array-zigzag) | Medium |
-| <span id="1145">1145</span> | [Binary Tree Coloring Game](https://leetcode.com/problems/binary-tree-coloring-game "二叉树着色游戏") | [Go](../problems/binary-tree-coloring-game) | Medium |
-| <span id="1146">1146</span> | [Snapshot Array](https://leetcode.com/problems/snapshot-array "快照数组") | [Go](../problems/snapshot-array) | Medium |
-| <span id="1147">1147</span> | [Longest Chunked Palindrome Decomposition](https://leetcode.com/problems/longest-chunked-palindrome-decomposition "段式回文") | [Go](../problems/longest-chunked-palindrome-decomposition) | Hard |
-| <span id="1148">1148</span> | [Article Views I](https://leetcode.com/problems/article-views-i "文章浏览 I") 🔒 | [MySQL](../problems/article-views-i) | Easy |
-| <span id="1149">1149</span> | [Article Views II](https://leetcode.com/problems/article-views-ii "文章浏览 II") 🔒 | [MySQL](../problems/article-views-ii) | Medium |
-| <span id="1150">1150</span> | [Check If a Number Is Majority Element in a Sorted Array](https://leetcode.com/problems/check-if-a-number-is-majority-element-in-a-sorted-array "检查一个数是否在数组中占绝大多数") 🔒 | [Go](../problems/check-if-a-number-is-majority-element-in-a-sorted-array) | Easy |
-| <span id="1151">1151</span> | [Minimum Swaps to Group All 1's Together](https://leetcode.com/problems/minimum-swaps-to-group-all-1s-together "最少交换次数来组合所有的 1") 🔒 | [Go](../problems/minimum-swaps-to-group-all-1s-together) | Medium |
-| <span id="1152">1152</span> | [Analyze User Website Visit Pattern](https://leetcode.com/problems/analyze-user-website-visit-pattern "用户网站访问行为分析") 🔒 | [Go](../problems/analyze-user-website-visit-pattern) | Medium |
-| <span id="1153">1153</span> | [String Transforms Into Another String](https://leetcode.com/problems/string-transforms-into-another-string "字符串转化") 🔒 | [Go](../problems/string-transforms-into-another-string) | Hard |
-| <span id="1154">1154</span> | [Day of the Year](https://leetcode.com/problems/day-of-the-year "一年中的第几天") | [Go](../problems/day-of-the-year) | Easy |
-| <span id="1155">1155</span> | [Number of Dice Rolls With Target Sum](https://leetcode.com/problems/number-of-dice-rolls-with-target-sum "掷骰子的N种方法") | [Go](../problems/number-of-dice-rolls-with-target-sum) | Medium |
-| <span id="1156">1156</span> | [Swap For Longest Repeated Character Substring](https://leetcode.com/problems/swap-for-longest-repeated-character-substring "单字符重复子串的最大长度") | [Go](../problems/swap-for-longest-repeated-character-substring) | Medium |
-| <span id="1157">1157</span> | [Online Majority Element In Subarray](https://leetcode.com/problems/online-majority-element-in-subarray "子数组中占绝大多数的元素") | [Go](../problems/online-majority-element-in-subarray) | Hard |
-| <span id="1158">1158</span> | [Market Analysis I](https://leetcode.com/problems/market-analysis-i "市场分析 I") 🔒 | [MySQL](../problems/market-analysis-i) | Medium |
-| <span id="1159">1159</span> | [Market Analysis II](https://leetcode.com/problems/market-analysis-ii "市场分析 II") 🔒 | [MySQL](../problems/market-analysis-ii) | Hard |
-| <span id="1160">1160</span> | [Find Words That Can Be Formed by Characters](https://leetcode.com/problems/find-words-that-can-be-formed-by-characters "拼写单词") | [Go](../problems/find-words-that-can-be-formed-by-characters) | Easy |
-| <span id="1161">1161</span> | [Maximum Level Sum of a Binary Tree](https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree "最大层内元素和") | [Go](../problems/maximum-level-sum-of-a-binary-tree) | Medium |
-| <span id="1162">1162</span> | [As Far from Land as Possible](https://leetcode.com/problems/as-far-from-land-as-possible "地图分析") | [Go](../problems/as-far-from-land-as-possible) | Medium |
-| <span id="1163">1163</span> | [Last Substring in Lexicographical Order](https://leetcode.com/problems/last-substring-in-lexicographical-order "按字典序排在最后的子串") | [Go](../problems/last-substring-in-lexicographical-order) | Hard |
-| <span id="1164">1164</span> | [Product Price at a Given Date](https://leetcode.com/problems/product-price-at-a-given-date "指定日期的产品价格") 🔒 | [MySQL](../problems/product-price-at-a-given-date) | Medium |
-| <span id="1165">1165</span> | [Single-Row Keyboard](https://leetcode.com/problems/single-row-keyboard "单行键盘") 🔒 | [Go](../problems/single-row-keyboard) | Easy |
-| <span id="1166">1166</span> | [Design File System](https://leetcode.com/problems/design-file-system "设计文件系统") 🔒 | [Go](../problems/design-file-system) | Medium |
-| <span id="1167">1167</span> | [Minimum Cost to Connect Sticks](https://leetcode.com/problems/minimum-cost-to-connect-sticks "连接棒材的最低费用") 🔒 | [Go](../problems/minimum-cost-to-connect-sticks) | Medium |
-| <span id="1168">1168</span> | [Optimize Water Distribution in a Village](https://leetcode.com/problems/optimize-water-distribution-in-a-village "水资源分配优化") 🔒 | [Go](../problems/optimize-water-distribution-in-a-village) | Hard |
-| <span id="1169">1169</span> | [Invalid Transactions](https://leetcode.com/problems/invalid-transactions "查询无效交易") | [Go](../problems/invalid-transactions) | Medium |
-| <span id="1170">1170</span> | [Compare Strings by Frequency of the Smallest Character](https://leetcode.com/problems/compare-strings-by-frequency-of-the-smallest-character "比较字符串最小字母出现频次") | [Go](../problems/compare-strings-by-frequency-of-the-smallest-character) | Medium |
-| <span id="1171">1171</span> | [Remove Zero Sum Consecutive Nodes from Linked List](https://leetcode.com/problems/remove-zero-sum-consecutive-nodes-from-linked-list "从链表中删去总和值为零的连续节点") | [Go](../problems/remove-zero-sum-consecutive-nodes-from-linked-list) | Medium |
-| <span id="1172">1172</span> | [Dinner Plate Stacks](https://leetcode.com/problems/dinner-plate-stacks "餐盘栈") | [Go](../problems/dinner-plate-stacks) | Hard |
-| <span id="1173">1173</span> | [Immediate Food Delivery I](https://leetcode.com/problems/immediate-food-delivery-i "即时食物配送 I") 🔒 | [MySQL](../problems/immediate-food-delivery-i) | Easy |
-| <span id="1174">1174</span> | [Immediate Food Delivery II](https://leetcode.com/problems/immediate-food-delivery-ii "即时食物配送 II") 🔒 | [MySQL](../problems/immediate-food-delivery-ii) | Medium |
-| <span id="1175">1175</span> | [Prime Arrangements](https://leetcode.com/problems/prime-arrangements "质数排列") | [Go](../problems/prime-arrangements) | Easy |
-| <span id="1176">1176</span> | [Diet Plan Performance](https://leetcode.com/problems/diet-plan-performance "健身计划评估") 🔒 | [Go](../problems/diet-plan-performance) | Easy |
-| <span id="1177">1177</span> | [Can Make Palindrome from Substring](https://leetcode.com/problems/can-make-palindrome-from-substring "构建回文串检测") | [Go](../problems/can-make-palindrome-from-substring) | Medium |
-| <span id="1178">1178</span> | [Number of Valid Words for Each Puzzle](https://leetcode.com/problems/number-of-valid-words-for-each-puzzle "猜字谜") | [Go](../problems/number-of-valid-words-for-each-puzzle) | Hard |
-| <span id="1179">1179</span> | [Reformat Department Table](https://leetcode.com/problems/reformat-department-table "重新格式化部门表") | [MySQL](../problems/reformat-department-table) | Easy |
-| <span id="1180">1180</span> | [Count Substrings with Only One Distinct Letter](https://leetcode.com/problems/count-substrings-with-only-one-distinct-letter "统计只含单一字母的子串") 🔒 | [Go](../problems/count-substrings-with-only-one-distinct-letter) | Easy |
-| <span id="1181">1181</span> | [Before and After Puzzle](https://leetcode.com/problems/before-and-after-puzzle "前后拼接") 🔒 | [Go](../problems/before-and-after-puzzle) | Medium |
-| <span id="1182">1182</span> | [Shortest Distance to Target Color](https://leetcode.com/problems/shortest-distance-to-target-color "与目标颜色间的最短距离") 🔒 | [Go](../problems/shortest-distance-to-target-color) | Medium |
-| <span id="1183">1183</span> | [Maximum Number of Ones](https://leetcode.com/problems/maximum-number-of-ones "矩阵中 1 的最大数量") 🔒 | [Go](../problems/maximum-number-of-ones) | Hard |
-| <span id="1184">1184</span> | [Distance Between Bus Stops](https://leetcode.com/problems/distance-between-bus-stops "公交站间的距离") | [Go](../problems/distance-between-bus-stops) | Easy |
-| <span id="1185">1185</span> | [Day of the Week](https://leetcode.com/problems/day-of-the-week "一周中的第几天") | [Go](../problems/day-of-the-week) | Easy |
-| <span id="1186">1186</span> | [Maximum Subarray Sum with One Deletion](https://leetcode.com/problems/maximum-subarray-sum-with-one-deletion "删除一次得到子数组最大和") | [Go](../problems/maximum-subarray-sum-with-one-deletion) | Medium |
-| <span id="1187">1187</span> | [Make Array Strictly Increasing](https://leetcode.com/problems/make-array-strictly-increasing "使数组严格递增") | [Go](../problems/make-array-strictly-increasing) | Hard |
-| <span id="1188">1188</span> | [Design Bounded Blocking Queue](https://leetcode.com/problems/design-bounded-blocking-queue "设计有限阻塞队列") 🔒 | [Go](../problems/design-bounded-blocking-queue) | Medium |
-| <span id="1189">1189</span> | [Maximum Number of Balloons](https://leetcode.com/problems/maximum-number-of-balloons "“气球” 的最大数量") | [Go](../problems/maximum-number-of-balloons) | Easy |
-| <span id="1190">1190</span> | [Reverse Substrings Between Each Pair of Parentheses](https://leetcode.com/problems/reverse-substrings-between-each-pair-of-parentheses "反转每对括号间的子串") | [Go](../problems/reverse-substrings-between-each-pair-of-parentheses) | Medium |
-| <span id="1191">1191</span> | [K-Concatenation Maximum Sum](https://leetcode.com/problems/k-concatenation-maximum-sum "K 次串联后最大子数组之和") | [Go](../problems/k-concatenation-maximum-sum) | Medium |
-| <span id="1192">1192</span> | [Critical Connections in a Network](https://leetcode.com/problems/critical-connections-in-a-network "查找集群内的「关键连接」") | [Go](../problems/critical-connections-in-a-network) | Hard |
-| <span id="1193">1193</span> | [Monthly Transactions I](https://leetcode.com/problems/monthly-transactions-i "每月交易 I") 🔒 | [MySQL](../problems/monthly-transactions-i) | Medium |
-| <span id="1194">1194</span> | [Tournament Winners](https://leetcode.com/problems/tournament-winners "锦标赛优胜者") 🔒 | [MySQL](../problems/tournament-winners) | Hard |
-| <span id="1195">1195</span> | [Fizz Buzz Multithreaded](https://leetcode.com/problems/fizz-buzz-multithreaded "交替打印字符串") | [Go](../problems/fizz-buzz-multithreaded) | Medium |
-| <span id="1196">1196</span> | [How Many Apples Can You Put into the Basket](https://leetcode.com/problems/how-many-apples-can-you-put-into-the-basket "最多可以买到的苹果数量") 🔒 | [Go](../problems/how-many-apples-can-you-put-into-the-basket) | Easy |
-| <span id="1197">1197</span> | [Minimum Knight Moves](https://leetcode.com/problems/minimum-knight-moves "进击的骑士") 🔒 | [Go](../problems/minimum-knight-moves) | Medium |
-| <span id="1198">1198</span> | [Find Smallest Common Element in All Rows](https://leetcode.com/problems/find-smallest-common-element-in-all-rows "找出所有行中最小公共元素") 🔒 | [Go](../problems/find-smallest-common-element-in-all-rows) | Medium |
-| <span id="1199">1199</span> | [Minimum Time to Build Blocks](https://leetcode.com/problems/minimum-time-to-build-blocks "建造街区的最短时间") 🔒 | [Go](../problems/minimum-time-to-build-blocks) | Hard |
-| <span id="1200">1200</span> | [Minimum Absolute Difference](https://leetcode.com/problems/minimum-absolute-difference "最小绝对差") | [Go](../problems/minimum-absolute-difference) | Easy |
diff --git a/tag/README.md b/tag/README.md
deleted file mode 100644
index a260ae4a8..000000000
--- a/tag/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## 话题分类
-
-| # | Topic | 话题 | | # | Topic | 话题 |
-| :-: | - | :-: | - | :-: | - | :-: |
-| 1 | [Array](array/README.md) | [数组](https://awesee.github.io/tags/array/) | | 2 | [Dynamic Programming](dynamic-programming/README.md) | [动态规划](https://awesee.github.io/tags/dynamic-programming/) | 
-| 3 | [String](string/README.md) | [字符串](https://awesee.github.io/tags/string/) | | 4 | [Math](math/README.md) | [数学](https://awesee.github.io/tags/math/) | 
-| 5 | [Greedy](greedy/README.md) | [贪心](https://awesee.github.io/tags/greedy/) | | 6 | [Depth-First Search](depth-first-search/README.md) | [深度优先搜索](https://awesee.github.io/tags/depth-first-search/) | 
-| 7 | [Tree](tree/README.md) | [树](https://awesee.github.io/tags/tree/) | | 8 | [Hash Table](hash-table/README.md) | [哈希表](https://awesee.github.io/tags/hash-table/) | 
-| 9 | [Binary Search](binary-search/README.md) | [二分查找](https://awesee.github.io/tags/binary-search/) | | 10 | [Breadth-First Search](breadth-first-search/README.md) | [广度优先搜索](https://awesee.github.io/tags/breadth-first-search/) | 
-| 11 | [Sort](sort/README.md) | [排序](https://awesee.github.io/tags/sort/) | | 12 | [Two Pointers](two-pointers/README.md) | [双指针](https://awesee.github.io/tags/two-pointers/) | 
-| 13 | [Backtracking](backtracking/README.md) | [回溯](https://awesee.github.io/tags/backtracking/) | | 14 | [Design](design/README.md) | [设计](https://awesee.github.io/tags/design/) | 
-| 15 | [Stack](stack/README.md) | [栈](https://awesee.github.io/tags/stack/) | | 16 | [Bit Manipulation](bit-manipulation/README.md) | [位运算](https://awesee.github.io/tags/bit-manipulation/) | 
-| 17 | [Graph](graph/README.md) | [图](https://awesee.github.io/tags/graph/) | | 18 | [Heap](heap/README.md) | [堆](https://awesee.github.io/tags/heap/) | 
-| 19 | [Linked List](linked-list/README.md) | [链表](https://awesee.github.io/tags/linked-list/) | | 20 | [Recursion](recursion/README.md) | [递归](https://awesee.github.io/tags/recursion/) | 
-| 21 | [Union Find](union-find/README.md) | [并查集](https://awesee.github.io/tags/union-find/) | | 22 | [Sliding Window](sliding-window/README.md) | [滑动窗口](https://awesee.github.io/tags/sliding-window/) | 
-| 23 | [Trie](trie/README.md) | [字典树](https://awesee.github.io/tags/trie/) | | 24 | [Divide and Conquer](divide-and-conquer/README.md) | [分治](https://awesee.github.io/tags/divide-and-conquer/) | 
-| 25 | [Ordered Map](ordered-map/README.md) | [Ordered Map](https://awesee.github.io/tags/ordered-map/) | | 26 | [Segment Tree](segment-tree/README.md) | [线段树](https://awesee.github.io/tags/segment-tree/) | 
-| 27 | [Queue](queue/README.md) | [队列](https://awesee.github.io/tags/queue/) | | 28 | [Geometry](geometry/README.md) | [几何](https://awesee.github.io/tags/geometry/) | 
-| 29 | [Line Sweep](line-sweep/README.md) | [扫描线](https://awesee.github.io/tags/line-sweep/) | | 30 | [Binary Indexed Tree](binary-indexed-tree/README.md) | [树状数组](https://awesee.github.io/tags/binary-indexed-tree/) | 
-| 31 | [Minimax](minimax/README.md) | [极小化极大](https://awesee.github.io/tags/minimax/) | | 32 | [Brainteaser](brainteaser/README.md) | [脑筋急转弯](https://awesee.github.io/tags/brainteaser/) | 
-| 33 | [Topological Sort](topological-sort/README.md) | [拓扑排序](https://awesee.github.io/tags/topological-sort/) | | 34 | [Dequeue](dequeue/README.md) | [Dequeue](https://awesee.github.io/tags/dequeue/) | 
-| 35 | [Random](random/README.md) | [Random](https://awesee.github.io/tags/random/) | | 36 | [Binary Search Tree](binary-search-tree/README.md) | [二叉搜索树](https://awesee.github.io/tags/binary-search-tree/) | 
-| 37 | [Rolling Hash](rolling-hash/README.md) | [滚动哈希](https://awesee.github.io/tags/rolling-hash/) | | 38 | [Suffix Array](suffix-array/README.md) | [后缀数组](https://awesee.github.io/tags/suffix-array/) | 
-| 39 | [Rejection Sampling](rejection-sampling/README.md) | [拒绝采样](https://awesee.github.io/tags/rejection-sampling/) | | 40 | [Reservoir Sampling](reservoir-sampling/README.md) | [水塘抽样](https://awesee.github.io/tags/reservoir-sampling/) | 
-| 41 | [Meet In The Middle](meet-in-the-middle/README.md) | [Meet In The Middle](https://awesee.github.io/tags/meet-in-the-middle/) | | 42 | [Memoization](memoization/README.md) | [记忆化搜索](https://awesee.github.io/tags/memoization/) | 
-| 43 | [OOP](oop/README.md) | [OOP](https://awesee.github.io/tags/oop/) | | 44 | [Sorting](sorting/README.md) | [排序](https://awesee.github.io/tags/sorting/) | 
-| 45 | [Heap (Priority Queue)](heap-priority-queue/README.md) | [堆（优先队列）](https://awesee.github.io/tags/heap-priority-queue/) | | 46 | [Ordered Set](ordered-set/README.md) | [有序集合](https://awesee.github.io/tags/ordered-set/) | 
-| 47 | [Hash Function](hash-function/README.md) | [哈希函数](https://awesee.github.io/tags/hash-function/) | | 48 | [String Matching](string-matching/README.md) | [字符串匹配](https://awesee.github.io/tags/string-matching/) | 
-| 49 | [Randomized](randomized/README.md) | [随机化](https://awesee.github.io/tags/randomized/) | | 50 | [Prefix Sum](prefix-sum/README.md) | [前缀和](https://awesee.github.io/tags/prefix-sum/) | 
-| 51 | [Probability and Statistics](probability-and-statistics/README.md) | [概率与统计](https://awesee.github.io/tags/probability-and-statistics/) | | 52 | [Simulation](simulation/README.md) | [模拟](https://awesee.github.io/tags/simulation/) | 
-| 53 | [Monotonic Queue](monotonic-queue/README.md) | [单调队列](https://awesee.github.io/tags/monotonic-queue/) | | 54 | [Data Stream](data-stream/README.md) | [数据流](https://awesee.github.io/tags/data-stream/) | 
-| 55 | [Counting](counting/README.md) | [计数](https://awesee.github.io/tags/counting/) | | 56 | [Matrix](matrix/README.md) | [矩阵](https://awesee.github.io/tags/matrix/) | 
-| 57 | [Iterator](iterator/README.md) | [迭代器](https://awesee.github.io/tags/iterator/) | | 58 | [Quickselect](quickselect/README.md) | [快速选择](https://awesee.github.io/tags/quickselect/) | 
-| 59 | [Merge Sort](merge-sort/README.md) | [归并排序](https://awesee.github.io/tags/merge-sort/) | | 60 | [Binary Tree](binary-tree/README.md) | [二叉树](https://awesee.github.io/tags/binary-tree/) | 
-| 61 | [Combinatorics](combinatorics/README.md) | [组合数学](https://awesee.github.io/tags/combinatorics/) | | 62 | [Shortest Path](shortest-path/README.md) | [最短路](https://awesee.github.io/tags/shortest-path/) | 
-| 63 | [Interactive](interactive/README.md) | [交互](https://awesee.github.io/tags/interactive/) | | 64 | [Bucket Sort](bucket-sort/README.md) | [桶排序](https://awesee.github.io/tags/bucket-sort/) | 
-| 65 | [Counting Sort](counting-sort/README.md) | [计数排序](https://awesee.github.io/tags/counting-sort/) | | 66 | [Radix Sort](radix-sort/README.md) | [基数排序](https://awesee.github.io/tags/radix-sort/) | 
-| 67 | [Monotonic Stack](monotonic-stack/README.md) | [单调栈](https://awesee.github.io/tags/monotonic-stack/) | | 68 | [Minimum Spanning Tree](minimum-spanning-tree/README.md) | [最小生成树](https://awesee.github.io/tags/minimum-spanning-tree/) | 
-| 69 | [Strongly Connected Component](strongly-connected-component/README.md) | [强连通分量](https://awesee.github.io/tags/strongly-connected-component/) | | 70 | [Game Theory](game-theory/README.md) | [博弈](https://awesee.github.io/tags/game-theory/) | 
-| 71 | [Bitmask](bitmask/README.md) | [状态压缩](https://awesee.github.io/tags/bitmask/) | | 72 | [Concurrency](concurrency/README.md) | [多线程](https://awesee.github.io/tags/concurrency/) | 
-| 73 | [Doubly-Linked List](doubly-linked-list/README.md) | [双向链表](https://awesee.github.io/tags/doubly-linked-list/) | | 74 | [Enumeration](enumeration/README.md) | [枚举](https://awesee.github.io/tags/enumeration/) | 
-| 75 | [Number Theory](number-theory/README.md) | [数论](https://awesee.github.io/tags/number-theory/) | | 76 | [Biconnected Component](biconnected-component/README.md) | [双连通分量](https://awesee.github.io/tags/biconnected-component/) | 
-| 77 | [Eulerian Circuit](eulerian-circuit/README.md) | [欧拉回路](https://awesee.github.io/tags/eulerian-circuit/) | 
\ No newline at end of file
diff --git a/tag/array/README.md b/tag/array/README.md
deleted file mode 100644
index ef5f632f3..000000000
--- a/tag/array/README.md
+++ /dev/null
@@ -1,1052 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 数组
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2172 | [数组的最大与和](../../problems/maximum-and-sum-of-array) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 2171 | [拿出最少数目的魔法豆](../../problems/removing-minimum-number-of-magic-beans) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2170 | [使数组变成交替数组的最少操作数](../../problems/minimum-operations-to-make-the-array-alternating) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2166 | [设计位集](../../problems/design-bitset) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 2164 | [对奇偶下标分别排序](../../problems/sort-even-and-odd-indices-independently) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2163 | [删除元素后和的最小差值](../../problems/minimum-difference-in-sums-after-removal-of-elements) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 2161 | [根据给定数字划分数组](../../problems/partition-array-according-to-given-pivot) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2158 | [Amount of New Area Painted Each Day](../../problems/amount-of-new-area-painted-each-day) 🔒 | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2155 | [分组得分最高的所有下标](../../problems/all-divisions-with-the-highest-score-of-a-binary-array) | [[数组](../array/README.md)]  | Medium |
-| 2154 | [将找到的值乘以 2](../../problems/keep-multiplying-found-values-by-two) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2152 | [Minimum Number of Lines to Cover Points](../../problems/minimum-number-of-lines-to-cover-points) 🔒 | [[位运算](../bit-manipulation/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 2151 | [基于陈述统计最多好人数](../../problems/maximum-good-people-based-on-statements) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2150 | [找出数组中的所有孤独数字](../../problems/find-all-lonely-numbers-in-the-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2149 | [按符号重排数组](../../problems/rearrange-array-elements-by-sign) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2148 | [元素计数](../../problems/count-elements-with-strictly-smaller-and-greater-elements) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2146 | [价格范围内最高排名的 K 样物品](../../problems/k-highest-ranked-items-within-a-price-range) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2145 | [统计隐藏数组数目](../../problems/count-the-hidden-sequences) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2144 | [打折购买糖果的最小开销](../../problems/minimum-cost-of-buying-candies-with-discount) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2143 | [Choose Numbers From Two Arrays in Range](../../problems/choose-numbers-from-two-arrays-in-range) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2141 | [同时运行 N 台电脑的最长时间](../../problems/maximum-running-time-of-n-computers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2140 | [解决智力问题](../../problems/solving-questions-with-brainpower) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2137 | [Pour Water Between Buckets to Make Water Levels Equal](../../problems/pour-water-between-buckets-to-make-water-levels-equal) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 2136 | [全部开花的最早一天](../../problems/earliest-possible-day-of-full-bloom) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2135 | [统计追加字母可以获得的单词数](../../problems/count-words-obtained-after-adding-a-letter) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2134 | [最少交换次数来组合所有的 1 II](../../problems/minimum-swaps-to-group-all-1s-together-ii) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2133 | [检查是否每一行每一列都包含全部整数](../../problems/check-if-every-row-and-column-contains-all-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 2132 | [用邮票贴满网格图](../../problems/stamping-the-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 2131 | [连接两字母单词得到的最长回文串](../../problems/longest-palindrome-by-concatenating-two-letter-words) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2128 | [Remove All Ones With Row and Column Flips](../../problems/remove-all-ones-with-row-and-column-flips) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2126 | [摧毁小行星](../../problems/destroying-asteroids) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2125 | [银行中的激光束数量](../../problems/number-of-laser-beams-in-a-bank) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2123 | [Minimum Operations to Remove Adjacent Ones in Matrix](../../problems/minimum-operations-to-remove-adjacent-ones-in-matrix) 🔒 | [[图](../graph/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 2122 | [还原原数组](../../problems/recover-the-original-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2121 | [相同元素的间隔之和](../../problems/intervals-between-identical-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2115 | [从给定原材料中找到所有可以做出的菜](../../problems/find-all-possible-recipes-from-given-supplies) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2114 | [句子中的最多单词数](../../problems/maximum-number-of-words-found-in-sentences) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2113 | [Elements in Array After Removing and Replacing Elements](../../problems/elements-in-array-after-removing-and-replacing-elements) 🔒 | [[数组](../array/README.md)]  | Medium |
-| 2111 | [使数组 K 递增的最少操作次数](../../problems/minimum-operations-to-make-the-array-k-increasing) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 2110 | [股票平滑下跌阶段的数目](../../problems/number-of-smooth-descent-periods-of-a-stock) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2109 | [向字符串添加空格](../../problems/adding-spaces-to-a-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2108 | [找出数组中的第一个回文字符串](../../problems/find-first-palindromic-string-in-the-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2107 | [Number of Unique Flavors After Sharing K Candies](../../problems/number-of-unique-flavors-after-sharing-k-candies) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2106 | [摘水果](../../problems/maximum-fruits-harvested-after-at-most-k-steps) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 2105 | [给植物浇水 II](../../problems/watering-plants-ii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2104 | [子数组范围和](../../problems/sum-of-subarray-ranges) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 2101 | [引爆最多的炸弹](../../problems/detonate-the-maximum-bombs) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 2100 | [适合打劫银行的日子](../../problems/find-good-days-to-rob-the-bank) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2099 | [找到和最大的长度为 K 的子序列](../../problems/find-subsequence-of-length-k-with-the-largest-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 2098 | [Subsequence of Size K With the Largest Even Sum](../../problems/subsequence-of-size-k-with-the-largest-even-sum) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2094 | [找出 3 位偶数](../../problems/finding-3-digit-even-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2091 | [从数组中移除最大值和最小值](../../problems/removing-minimum-and-maximum-from-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 2090 | [半径为 k 的子数组平均值](../../problems/k-radius-subarray-averages) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2089 | [找出数组排序后的目标下标](../../problems/find-target-indices-after-sorting-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2088 | [统计农场中肥沃金字塔的数目](../../problems/count-fertile-pyramids-in-a-land) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 2087 | [网格图中机器人回家的最小代价](../../problems/minimum-cost-homecoming-of-a-robot-in-a-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2085 | [统计出现过一次的公共字符串](../../problems/count-common-words-with-one-occurrence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2080 | [区间内查询数字的频率](../../problems/range-frequency-queries) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 2079 | [给植物浇水](../../problems/watering-plants) | [[数组](../array/README.md)]  | Medium |
-| 2078 | [两栋颜色不同且距离最远的房子](../../problems/two-furthest-houses-with-different-colors) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 2073 | [买票需要的时间](../../problems/time-needed-to-buy-tickets) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2071 | [你可以安排的最多任务数目](../../problems/maximum-number-of-tasks-you-can-assign) | [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Hard |
-| 2070 | [每一个查询的最大美丽值](../../problems/most-beautiful-item-for-each-query) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2065 | [最大化一张图中的路径价值](../../problems/maximum-path-quality-of-a-graph) | [[图](../graph/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 2064 | [分配给商店的最多商品的最小值](../../problems/minimized-maximum-of-products-distributed-to-any-store) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 2061 | [扫地机器人清扫过的空间个数](../../problems/number-of-spaces-cleaning-robot-cleaned) 🔒 | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2059 | [转化数字的最小运算数](../../problems/minimum-operations-to-convert-number) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)]  | Medium |
-| 2057 | [值相等的最小索引](../../problems/smallest-index-with-equal-value) | [[数组](../array/README.md)]  | Easy |
-| 2056 | [棋盘上有效移动组合的数目](../../problems/number-of-valid-move-combinations-on-chessboard) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 2055 | [蜡烛之间的盘子](../../problems/plates-between-candles) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2054 | [两个最好的不重叠活动](../../problems/two-best-non-overlapping-events) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2053 | [数组中第 K 个独一无二的字符串](../../problems/kth-distinct-string-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2052 | [将句子分隔成行的最低成本](../../problems/minimum-cost-to-separate-sentence-into-rows) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2049 | [统计最高分的节点数目](../../problems/count-nodes-with-the-highest-score) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 2044 | [统计按位或能得到最大值的子集数目](../../problems/count-number-of-maximum-bitwise-or-subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 2043 | [简易银行系统](../../problems/simple-bank-system) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2040 | [两个有序数组的第 K 小乘积](../../problems/kth-smallest-product-of-two-sorted-arrays) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 2039 | [网络空闲的时刻](../../problems/the-time-when-the-network-becomes-idle) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)]  | Medium |
-| 2037 | [使每位学生都有座位的最少移动次数](../../problems/minimum-number-of-moves-to-seat-everyone) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2036 | [最大交替子数组和](../../problems/maximum-alternating-subarray-sum) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2035 | [将数组分成两个数组并最小化数组和的差](../../problems/partition-array-into-two-arrays-to-minimize-sum-difference) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2033 | [获取单值网格的最小操作数](../../problems/minimum-operations-to-make-a-uni-value-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2032 | [至少在两个数组中出现的值](../../problems/two-out-of-three) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 2031 | [1 比 0 多的子数组个数](../../problems/count-subarrays-with-more-ones-than-zeros) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 2029 | [石子游戏 IX](../../problems/stone-game-ix) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 2028 | [找出缺失的观测数据](../../problems/find-missing-observations) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2025 | [分割数组的最多方案数](../../problems/maximum-number-of-ways-to-partition-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 2023 | [连接后等于目标字符串的字符串对](../../problems/number-of-pairs-of-strings-with-concatenation-equal-to-target) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2022 | [将一维数组转变成二维数组](../../problems/convert-1d-array-into-2d-array) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2021 | [街上最亮的位置](../../problems/brightest-position-on-street) 🔒 | [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2019 | [解出数学表达式的学生分数](../../problems/the-score-of-students-solving-math-expression) | [[栈](../stack/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2018 | [判断单词是否能放入填字游戏内](../../problems/check-if-word-can-be-placed-in-crossword) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2017 | [网格游戏](../../problems/grid-game) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2016 | [增量元素之间的最大差值](../../problems/maximum-difference-between-increasing-elements) | [[数组](../array/README.md)]  | Easy |
-| 2015 | [Average Height of Buildings in Each Segment](../../problems/average-height-of-buildings-in-each-segment) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2013 | [检测正方形](../../problems/detect-squares) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2012 | [数组美丽值求和](../../problems/sum-of-beauty-in-the-array) | [[数组](../array/README.md)]  | Medium |
-| 2011 | [执行操作后的变量值](../../problems/final-value-of-variable-after-performing-operations) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2009 | [使数组连续的最少操作数](../../problems/minimum-number-of-operations-to-make-array-continuous) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 2008 | [出租车的最大盈利](../../problems/maximum-earnings-from-taxi) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2007 | [从双倍数组中还原原数组](../../problems/find-original-array-from-doubled-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2006 | [差的绝对值为 K 的数对数目](../../problems/count-number-of-pairs-with-absolute-difference-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2001 | [可互换矩形的组数](../../problems/number-of-pairs-of-interchangeable-rectangles) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1998 | [数组的最大公因数排序](../../problems/gcd-sort-of-an-array) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1997 | [访问完所有房间的第一天](../../problems/first-day-where-you-have-been-in-all-the-rooms) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1996 | [游戏中弱角色的数量](../../problems/the-number-of-weak-characters-in-the-game) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1995 | [统计特殊四元组](../../problems/count-special-quadruplets) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 1994 | [好子集的数目](../../problems/the-number-of-good-subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1992 | [找到所有的农场组](../../problems/find-all-groups-of-farmland) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1991 | [找到数组的中间位置](../../problems/find-the-middle-index-in-array) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1986 | [完成任务的最少工作时间段](../../problems/minimum-number-of-work-sessions-to-finish-the-tasks) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1985 | [找出数组中的第 K 大整数](../../problems/find-the-kth-largest-integer-in-the-array) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1984 | [学生分数的最小差值](../../problems/minimum-difference-between-highest-and-lowest-of-k-scores) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1982 | [从子集的和还原数组](../../problems/find-array-given-subset-sums) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)]  | Hard |
-| 1981 | [最小化目标值与所选元素的差](../../problems/minimize-the-difference-between-target-and-chosen-elements) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1980 | [找出不同的二进制字符串](../../problems/find-unique-binary-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1979 | [找出数组的最大公约数](../../problems/find-greatest-common-divisor-of-array) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1975 | [最大方阵和](../../problems/maximum-matrix-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1970 | [你能穿过矩阵的最后一天](../../problems/last-day-where-you-can-still-cross) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1968 | [构造元素不等于两相邻元素平均值的数组](../../problems/array-with-elements-not-equal-to-average-of-neighbors) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1964 | [找出到每个位置为止最长的有效障碍赛跑路线](../../problems/find-the-longest-valid-obstacle-course-at-each-position) | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1962 | [移除石子使总数最小](../../problems/remove-stones-to-minimize-the-total) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1961 | [检查字符串是否为数组前缀](../../problems/check-if-string-is-a-prefix-of-array) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1959 | [K 次调整数组大小浪费的最小总空间](../../problems/minimum-total-space-wasted-with-k-resizing-operations) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1958 | [检查操作是否合法](../../problems/check-if-move-is-legal) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1956 | [感染 K 种病毒所需的最短时间](../../problems/minimum-time-for-k-virus-variants-to-spread) 🔒 | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1955 | [统计特殊子序列的数目](../../problems/count-number-of-special-subsequences) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1953 | [你可以工作的最大周数](../../problems/maximum-number-of-weeks-for-which-you-can-work) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1950 | [所有子数组最小值中的最大值](../../problems/maximum-of-minimum-values-in-all-subarrays) 🔒 | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1948 | [删除系统中的重复文件夹](../../problems/delete-duplicate-folders-in-system) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 1947 | [最大兼容性评分和](../../problems/maximum-compatibility-score-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1946 | [子字符串突变后可能得到的最大整数](../../problems/largest-number-after-mutating-substring) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1944 | [队列中可以看到的人数](../../problems/number-of-visible-people-in-a-queue) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1943 | [描述绘画结果](../../problems/describe-the-painting) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1942 | [最小未被占据椅子的编号](../../problems/the-number-of-the-smallest-unoccupied-chair) | [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1940 | [排序数组之间的最长公共子序列](../../problems/longest-common-subsequence-between-sorted-arrays) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1936 | [新增的最少台阶数](../../problems/add-minimum-number-of-rungs) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1929 | [数组串联](../../problems/concatenation-of-array) | [[数组](../array/README.md)]  | Easy |
-| 1926 | [迷宫中离入口最近的出口](../../problems/nearest-exit-from-entrance-in-maze) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1924 | [安装栅栏 II](../../problems/erect-the-fence-ii) 🔒 | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1923 | [最长公共子路径](../../problems/longest-common-subpath) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1921 | [消灭怪物的最大数量](../../problems/eliminate-maximum-number-of-monsters) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1920 | [基于排列构建数组](../../problems/build-array-from-permutation) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1918 | [第 K 小的子数组和·](../../problems/kth-smallest-subarray-sum) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1914 | [循环轮转矩阵](../../problems/cyclically-rotating-a-grid) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1913 | [两个数对之间的最大乘积差](../../problems/maximum-product-difference-between-two-pairs) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1912 | [设计电影租借系统](../../problems/design-movie-rental-system) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1911 | [最大子序列交替和](../../problems/maximum-alternating-subsequence-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1909 | [删除一个元素使数组严格递增](../../problems/remove-one-element-to-make-the-array-strictly-increasing) | [[数组](../array/README.md)]  | Easy |
-| 1908 | [Nim 游戏 II](../../problems/game-of-nim) 🔒 | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1906 | [查询差绝对值的最小值](../../problems/minimum-absolute-difference-queries) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1905 | [统计子岛屿](../../problems/count-sub-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1901 | [找出顶峰元素 II](../../problems/find-a-peak-element-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1899 | [合并若干三元组以形成目标三元组](../../problems/merge-triplets-to-form-target-triplet) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1898 | [可移除字符的最大数目](../../problems/maximum-number-of-removable-characters) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1895 | [最大的幻方](../../problems/largest-magic-square) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1894 | [找到需要补充粉笔的学生编号](../../problems/find-the-student-that-will-replace-the-chalk) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1893 | [检查是否区域内所有整数都被覆盖](../../problems/check-if-all-the-integers-in-a-range-are-covered) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1891 | [割绳子](../../problems/cutting-ribbons) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1889 | [装包裹的最小浪费空间](../../problems/minimum-space-wasted-from-packaging) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1887 | [使数组元素相等的减少操作次数](../../problems/reduction-operations-to-make-the-array-elements-equal) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1886 | [判断矩阵经轮转后是否一致](../../problems/determine-whether-matrix-can-be-obtained-by-rotation) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1885 | [统计数对](../../problems/count-pairs-in-two-arrays) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1883 | [准时抵达会议现场的最小跳过休息次数](../../problems/minimum-skips-to-arrive-at-meeting-on-time) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1882 | [使用服务器处理任务](../../problems/process-tasks-using-servers) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1879 | [两个数组最小的异或值之和](../../problems/minimum-xor-sum-of-two-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1878 | [矩阵中最大的三个菱形和](../../problems/get-biggest-three-rhombus-sums-in-a-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1877 | [数组中最大数对和的最小值](../../problems/minimize-maximum-pair-sum-in-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1874 | [两个数组的最小乘积和](../../problems/minimize-product-sum-of-two-arrays) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1872 | [石子游戏 VIII](../../problems/stone-game-viii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1870 | [准时到达的列车最小时速](../../problems/minimum-speed-to-arrive-on-time) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1868 | [两个行程编码数组的积](../../problems/product-of-two-run-length-encoded-arrays) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1865 | [找出和为指定值的下标对](../../problems/finding-pairs-with-a-certain-sum) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1863 | [找出所有子集的异或总和再求和](../../problems/sum-of-all-subset-xor-totals) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)]  | Easy |
-| 1862 | [向下取整数对和](../../problems/sum-of-floored-pairs) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1861 | [旋转盒子](../../problems/rotating-the-box) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1856 | [子数组最小乘积的最大值](../../problems/maximum-subarray-min-product) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1855 | [下标对中的最大距离](../../problems/maximum-distance-between-a-pair-of-values) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1854 | [人口最多的年份](../../problems/maximum-population-year) | [[数组](../array/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1852 | [每个子数组的数字种类数](../../problems/distinct-numbers-in-each-subarray) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1851 | [包含每个查询的最小区间](../../problems/minimum-interval-to-include-each-query) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1848 | [到目标元素的最小距离](../../problems/minimum-distance-to-the-target-element) | [[数组](../array/README.md)]  | Easy |
-| 1847 | [最近的房间](../../problems/closest-room) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1846 | [减小和重新排列数组后的最大元素](../../problems/maximum-element-after-decreasing-and-rearranging) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1840 | [最高建筑高度](../../problems/maximum-building-height) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1838 | [最高频元素的频数](../../problems/frequency-of-the-most-frequent-element) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1835 | [所有数对按位与结果的异或和](../../problems/find-xor-sum-of-all-pairs-bitwise-and) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1834 | [单线程 CPU](../../problems/single-threaded-cpu) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1833 | [雪糕的最大数量](../../problems/maximum-ice-cream-bars) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1829 | [每个查询的最大异或值](../../problems/maximum-xor-for-each-query) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1828 | [统计一个圆中点的数目](../../problems/queries-on-number-of-points-inside-a-circle) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1827 | [最少操作使数组递增](../../problems/minimum-operations-to-make-the-array-increasing) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 1826 | [有缺陷的传感器](../../problems/faulty-sensor) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 1824 | [最少侧跳次数](../../problems/minimum-sideway-jumps) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1823 | [找出游戏的获胜者](../../problems/find-the-winner-of-the-circular-game) | [[递归](../recursion/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1822 | [数组元素积的符号](../../problems/sign-of-the-product-of-an-array) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1820 | [最多邀请的个数](../../problems/maximum-number-of-accepted-invitations) 🔒 | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1819 | [序列中不同最大公约数的数目](../../problems/number-of-different-subsequences-gcds) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1818 | [绝对差值和](../../problems/minimum-absolute-sum-difference) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1817 | [查找用户活跃分钟数](../../problems/finding-the-users-active-minutes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1816 | [截断句子](../../problems/truncate-sentence) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1815 | [得到新鲜甜甜圈的最多组数](../../problems/maximum-number-of-groups-getting-fresh-donuts) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1814 | [统计一个数组中好对子的数目](../../problems/count-nice-pairs-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1813 | [句子相似性 III](../../problems/sentence-similarity-iii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1807 | [替换字符串中的括号内容](../../problems/evaluate-the-bracket-pairs-of-a-string) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1806 | [还原排列的最少操作步数](../../problems/minimum-number-of-operations-to-reinitialize-a-permutation) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1803 | [统计异或值在范围内的数对有多少](../../problems/count-pairs-with-xor-in-a-range) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1801 | [积压订单中的订单总数](../../problems/number-of-orders-in-the-backlog) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1800 | [最大升序子数组和](../../problems/maximum-ascending-subarray-sum) | [[数组](../array/README.md)]  | Easy |
-| 1799 | [N 次操作后的最大分数和](../../problems/maximize-score-after-n-operations) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1798 | [你能构造出连续值的最大数目](../../problems/maximum-number-of-consecutive-values-you-can-make) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1793 | [好子数组的最大分数](../../problems/maximum-score-of-a-good-subarray) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1792 | [最大平均通过率](../../problems/maximum-average-pass-ratio) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1788 | [最大化花园的美观度](../../problems/maximize-the-beauty-of-the-garden) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1787 | [使所有区间的异或结果为零](../../problems/make-the-xor-of-all-segments-equal-to-zero) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1785 | [构成特定和需要添加的最少元素](../../problems/minimum-elements-to-add-to-form-a-given-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1779 | [找到最近的有相同 X 或 Y 坐标的点](../../problems/find-nearest-point-that-has-the-same-x-or-y-coordinate) | [[数组](../array/README.md)]  | Easy |
-| 1776 | [车队 II](../../problems/car-fleet-ii) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[单调栈](../monotonic-stack/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1775 | [通过最少操作次数使数组的和相等](../../problems/equal-sum-arrays-with-minimum-number-of-operations) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1774 | [最接近目标价格的甜点成本](../../problems/closest-dessert-cost) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1773 | [统计匹配检索规则的物品数量](../../problems/count-items-matching-a-rule) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1772 | [按受欢迎程度排列功能](../../problems/sort-features-by-popularity) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1770 | [执行乘法运算的最大分数](../../problems/maximum-score-from-performing-multiplication-operations) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1769 | [移动所有球到每个盒子所需的最小操作数](../../problems/minimum-number-of-operations-to-move-all-balls-to-each-box) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1765 | [地图中的最高点](../../problems/map-of-highest-peak) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1764 | [通过连接另一个数组的子数组得到一个数组](../../problems/form-array-by-concatenating-subarrays-of-another-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 1762 | [能看到海景的建筑物](../../problems/buildings-with-an-ocean-view) 🔒 | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1760 | [袋子里最少数目的球](../../problems/minimum-limit-of-balls-in-a-bag) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1756 | [设计最近使用（MRU）队列](../../problems/design-most-recently-used-queue) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1755 | [最接近目标值的子序列和](../../problems/closest-subsequence-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1752 | [检查数组是否经排序和轮转得到](../../problems/check-if-array-is-sorted-and-rotated) | [[数组](../array/README.md)]  | Easy |
-| 1751 | [最多可以参加的会议数目 II](../../problems/maximum-number-of-events-that-can-be-attended-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1749 | [任意子数组和的绝对值的最大值](../../problems/maximum-absolute-sum-of-any-subarray) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1748 | [唯一元素的和](../../problems/sum-of-unique-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1746 | [经过一次操作后的最大子数组和](../../problems/maximum-subarray-sum-after-one-operation) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1744 | [你能在你最喜欢的那天吃到你最喜欢的糖果吗？](../../problems/can-you-eat-your-favorite-candy-on-your-favorite-day) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1743 | [从相邻元素对还原数组](../../problems/restore-the-array-from-adjacent-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1738 | [找出第 K 大的异或坐标值](../../problems/find-kth-largest-xor-coordinate-value) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[快速选择](../quickselect/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1735 | [生成乘积数组的方案数](../../problems/count-ways-to-make-array-with-product) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1734 | [解码异或后的排列](../../problems/decode-xored-permutation) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1733 | [需要教语言的最少人数](../../problems/minimum-number-of-people-to-teach) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1732 | [找到最高海拔](../../problems/find-the-highest-altitude) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1730 | [获取食物的最短路径](../../problems/shortest-path-to-get-food) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1727 | [重新排列后的最大子矩阵](../../problems/largest-submatrix-with-rearrangements) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1726 | [同积元组](../../problems/tuple-with-same-product) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1725 | [可以形成最大正方形的矩形数目](../../problems/number-of-rectangles-that-can-form-the-largest-square) | [[数组](../array/README.md)]  | Easy |
-| 1723 | [完成所有工作的最短时间](../../problems/find-minimum-time-to-finish-all-jobs) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1722 | [执行交换操作后的最小汉明距离](../../problems/minimize-hamming-distance-after-swap-operations) | [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1720 | [解码异或后的数组](../../problems/decode-xored-array) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Easy |
-| 1718 | [构建字典序最大的可行序列](../../problems/construct-the-lexicographically-largest-valid-sequence) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1714 | [数组中特殊等间距元素的和](../../problems/sum-of-special-evenly-spaced-elements-in-array) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1713 | [得到子序列的最少操作次数](../../problems/minimum-operations-to-make-a-subsequence) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1712 | [将数组分成三个子数组的方案数](../../problems/ways-to-split-array-into-three-subarrays) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1711 | [大餐计数](../../problems/count-good-meals) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1710 | [卡车上的最大单元数](../../problems/maximum-units-on-a-truck) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1708 | [长度为 K 的最大子数组](../../problems/largest-subarray-length-k) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 1707 | [与数组中元素的最大异或值](../../problems/maximum-xor-with-an-element-from-array) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1706 | [球会落何处](../../problems/where-will-the-ball-fall) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1705 | [吃苹果的最大数目](../../problems/maximum-number-of-eaten-apples) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1703 | [得到连续 K 个 1 的最少相邻交换次数](../../problems/minimum-adjacent-swaps-for-k-consecutive-ones) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 1701 | [平均等待时间](../../problems/average-waiting-time) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1700 | [无法吃午餐的学生数量](../../problems/number-of-students-unable-to-eat-lunch) | [[栈](../stack/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1697 | [检查边长度限制的路径是否存在](../../problems/checking-existence-of-edge-length-limited-paths) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1696 | [跳跃游戏 VI](../../problems/jump-game-vi) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1695 | [删除子数组的最大得分](../../problems/maximum-erasure-value) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1691 | [堆叠长方体的最大高度](../../problems/maximum-height-by-stacking-cuboids) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1690 | [石子游戏 VII](../../problems/stone-game-vii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1687 | [从仓库到码头运输箱子](../../problems/delivering-boxes-from-storage-to-ports) | [[线段树](../segment-tree/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1686 | [石子游戏 VI](../../problems/stone-game-vi) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1685 | [有序数组中差绝对值之和](../../problems/sum-of-absolute-differences-in-a-sorted-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1684 | [统计一致字符串的数目](../../problems/count-the-number-of-consistent-strings) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1681 | [最小不兼容性](../../problems/minimum-incompatibility) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1679 | [K 和数对的最大数目](../../problems/max-number-of-k-sum-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1675 | [数组的最小偏移量](../../problems/minimize-deviation-in-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1674 | [使数组互补的最少操作次数](../../problems/minimum-moves-to-make-array-complementary) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1673 | [找出最具竞争力的子序列](../../problems/find-the-most-competitive-subsequence) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1672 | [最富有客户的资产总量](../../problems/richest-customer-wealth) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1671 | [得到山形数组的最少删除次数](../../problems/minimum-number-of-removals-to-make-mountain-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1670 | [设计前中后队列](../../problems/design-front-middle-back-queue) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1665 | [完成所有任务的最少初始能量](../../problems/minimum-initial-energy-to-finish-tasks) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1664 | [生成平衡数组的方案数](../../problems/ways-to-make-a-fair-array) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1662 | [检查两个字符串数组是否相等](../../problems/check-if-two-string-arrays-are-equivalent) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1658 | [将 x 减到 0 的最小操作数](../../problems/minimum-operations-to-reduce-x-to-zero) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1656 | [设计有序流](../../problems/design-an-ordered-stream) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 1655 | [分配重复整数](../../problems/distribute-repeating-integers) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1654 | [到家的最少跳跃次数](../../problems/minimum-jumps-to-reach-home) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1652 | [拆炸弹](../../problems/defuse-the-bomb) | [[数组](../array/README.md)]  | Easy |
-| 1649 | [通过指令创建有序数组](../../problems/create-sorted-array-through-instructions) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 1648 | [销售价值减少的颜色球](../../problems/sell-diminishing-valued-colored-balls) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1646 | [获取生成数组中的最大值](../../problems/get-maximum-in-generated-array) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1643 | [第 K 条最小指令](../../problems/kth-smallest-instructions) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1642 | [可以到达的最远建筑](../../problems/furthest-building-you-can-reach) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1640 | [能否连接形成数组](../../problems/check-array-formation-through-concatenation) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 1639 | [通过给定词典构造目标字符串的方案数](../../problems/number-of-ways-to-form-a-target-string-given-a-dictionary) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1637 | [两点之间不包含任何点的最宽垂直面积](../../problems/widest-vertical-area-between-two-points-containing-no-points) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1636 | [按照频率将数组升序排序](../../problems/sort-array-by-increasing-frequency) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1632 | [矩阵转换后的秩](../../problems/rank-transform-of-a-matrix) | [[贪心](../greedy/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1631 | [最小体力消耗路径](../../problems/path-with-minimum-effort) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1630 | [等差子数组](../../problems/arithmetic-subarrays) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1629 | [按键持续时间最长的键](../../problems/slowest-key) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1627 | [带阈值的图连通性](../../problems/graph-connectivity-with-threshold) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1626 | [无矛盾的最佳球队](../../problems/best-team-with-no-conflicts) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1620 | [网络信号最好的坐标](../../problems/coordinate-with-maximum-network-quality) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 1619 | [删除某些元素后的数组均值](../../problems/mean-of-array-after-removing-some-elements) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1618 | [找出适应屏幕的最大字号](../../problems/maximum-font-to-fit-a-sentence-in-a-screen) 🔒 | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1610 | [可见点的最大数目](../../problems/maximum-number-of-visible-points) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 1608 | [特殊数组的特征值](../../problems/special-array-with-x-elements-greater-than-or-equal-x) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1606 | [找到处理最多请求的服务器](../../problems/find-servers-that-handled-most-number-of-requests) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1605 | [给定行和列的和求可行矩阵](../../problems/find-valid-matrix-given-row-and-column-sums) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1604 | [警告一小时内使用相同员工卡大于等于三次的人](../../problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1601 | [最多可达成的换楼请求数目](../../problems/maximum-number-of-achievable-transfer-requests) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1599 | [经营摩天轮的最大利润](../../problems/maximum-profit-of-operating-a-centennial-wheel) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1598 | [文件夹操作日志搜集器](../../problems/crawler-log-folder) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1595 | [连通两组点的最小成本](../../problems/minimum-cost-to-connect-two-groups-of-points) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1594 | [矩阵的最大非负积](../../problems/maximum-non-negative-product-in-a-matrix) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1591 | [奇怪的打印机 II](../../problems/strange-printer-ii) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1590 | [使数组和能被 P 整除](../../problems/make-sum-divisible-by-p) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1589 | [所有排列中的最大和](../../problems/maximum-sum-obtained-of-any-permutation) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1588 | [所有奇数长度子数组的和](../../problems/sum-of-all-odd-length-subarrays) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1584 | [连接所有点的最小费用](../../problems/min-cost-to-connect-all-points) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)]  | Medium |
-| 1583 | [统计不开心的朋友](../../problems/count-unhappy-friends) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1582 | [二进制矩阵中的特殊位置](../../problems/special-positions-in-a-binary-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1580 | [把箱子放进仓库里 II](../../problems/put-boxes-into-the-warehouse-ii) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1578 | [使绳子变成彩色的最短时间](../../problems/minimum-time-to-make-rope-colorful) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1577 | [数的平方等于两数乘积的方法数](../../problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1575 | [统计所有可行路径](../../problems/count-all-possible-routes) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1574 | [删除最短的子数组使剩余数组有序](../../problems/shortest-subarray-to-be-removed-to-make-array-sorted) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1572 | [矩阵对角线元素的和](../../problems/matrix-diagonal-sum) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1570 | [两个稀疏向量的点积](../../problems/dot-product-of-two-sparse-vectors) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1568 | [使陆地分离的最少天数](../../problems/minimum-number-of-days-to-disconnect-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
-| 1567 | [乘积为正数的最长子数组长度](../../problems/maximum-length-of-subarray-with-positive-product) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1566 | [重复至少 K 次且长度为 M 的模式](../../problems/detect-pattern-of-length-m-repeated-k-or-more-times) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 1564 | [把箱子放进仓库里 I](../../problems/put-boxes-into-the-warehouse-i) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1563 | [石子游戏 V](../../problems/stone-game-v) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1562 | [查找大小为 M 的最新分组](../../problems/find-latest-group-of-size-m) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1561 | [你可以获得的最大硬币数目](../../problems/maximum-number-of-coins-you-can-get) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1560 | [圆形赛道上经过次数最多的扇区](../../problems/most-visited-sector-in-a-circular-track) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1559 | [二维网格图中探测环](../../problems/detect-cycles-in-2d-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1558 | [得到目标数组的最少函数调用次数](../../problems/minimum-numbers-of-function-calls-to-make-target-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1552 | [两球之间的磁力](../../problems/magnetic-force-between-two-balls) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1550 | [存在连续三个奇数的数组](../../problems/three-consecutive-odds) | [[数组](../array/README.md)]  | Easy |
-| 1547 | [切棍子的最小成本](../../problems/minimum-cost-to-cut-a-stick) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1546 | [和为目标值且不重叠的非空子数组的最大数目](../../problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1539 | [第 k 个缺失的正整数](../../problems/kth-missing-positive-number) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 1538 | [找出隐藏数组中出现次数最多的元素](../../problems/guess-the-majority-in-a-hidden-array) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1537 | [最大得分](../../problems/get-the-maximum-score) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1536 | [排布二进制网格的最少交换次数](../../problems/minimum-swaps-to-arrange-a-binary-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1535 | [找出数组游戏的赢家](../../problems/find-the-winner-of-an-array-game) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1534 | [统计好三元组](../../problems/count-good-triplets) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 1533 | [找到最大整数的索引](../../problems/find-the-index-of-the-large-integer) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1528 | [重新排列字符串](../../problems/shuffle-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1526 | [形成目标数组的子数组最少增加次数](../../problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1524 | [和为奇数的子数组数目](../../problems/number-of-sub-arrays-with-odd-sum) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1521 | [找到最接近目标值的函数值](../../problems/find-a-value-of-a-mysterious-function-closest-to-target) | [[位运算](../bit-manipulation/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1512 | [好数对的数目](../../problems/number-of-good-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1509 | [三次操作后最大值与最小值的最小差](../../problems/minimum-difference-between-largest-and-smallest-value-in-three-moves) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1508 | [子数组和排序后的区间和](../../problems/range-sum-of-sorted-subarray-sums) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1504 | [统计全 1 子矩形](../../problems/count-submatrices-with-all-ones) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1503 | [所有蚂蚁掉下来前的最后一刻](../../problems/last-moment-before-all-ants-fall-out-of-a-plank) | [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1502 | [判断能否形成等差数列](../../problems/can-make-arithmetic-progression-from-sequence) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1499 | [满足不等式的最大值](../../problems/max-value-of-equation) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1498 | [满足条件的子序列数目](../../problems/number-of-subsequences-that-satisfy-the-given-sum-condition) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1497 | [检查数组对是否可以被 k 整除](../../problems/check-if-array-pairs-are-divisible-by-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1491 | [去掉最低工资和最高工资后的工资平均值](../../problems/average-salary-excluding-the-minimum-and-maximum-salary) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1488 | [避免洪水泛滥](../../problems/avoid-flood-in-the-city) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1487 | [保证文件名唯一](../../problems/making-file-names-unique) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1482 | [制作 m 束花所需的最少天数](../../problems/minimum-number-of-days-to-make-m-bouquets) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1481 | [不同整数的最少数目](../../problems/least-number-of-unique-integers-after-k-removals) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1480 | [一维数组的动态和](../../problems/running-sum-of-1d-array) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1478 | [安排邮筒](../../problems/allocate-mailboxes) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1477 | [找两个和为目标值且不重叠的子数组](../../problems/find-two-non-overlapping-sub-arrays-each-with-target-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1476 | [子矩形查询](../../problems/subrectangle-queries) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1475 | [商品折扣后的最终价格](../../problems/final-prices-with-a-special-discount-in-a-shop) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Easy |
-| 1473 | [粉刷房子 III](../../problems/paint-house-iii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1472 | [设计浏览器历史记录](../../problems/design-browser-history) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 1471 | [数组中的 k 个最强值](../../problems/the-k-strongest-values-in-an-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1470 | [重新排列数组](../../problems/shuffle-the-array) | [[数组](../array/README.md)]  | Easy |
-| 1465 | [切割后面积最大的蛋糕](../../problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1464 | [数组中两元素的最大乘积](../../problems/maximum-product-of-two-elements-in-an-array) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 1463 | [摘樱桃 II](../../problems/cherry-pickup-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1460 | [通过翻转子数组使两个数组相等](../../problems/make-two-arrays-equal-by-reversing-sub-arrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1458 | [两个子序列的最大点积](../../problems/max-dot-product-of-two-subsequences) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1453 | [圆形靶内的最大飞镖数量](../../problems/maximum-number-of-darts-inside-of-a-circular-dartboard) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1452 | [收藏清单](../../problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1450 | [在既定时间做作业的学生人数](../../problems/number-of-students-doing-homework-at-a-given-time) | [[数组](../array/README.md)]  | Easy |
-| 1449 | [数位成本和为目标值的最大数字](../../problems/form-largest-integer-with-digits-that-add-up-to-target) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1444 | [切披萨的方案数](../../problems/number-of-ways-of-cutting-a-pizza) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1442 | [形成两个异或相等数组的三元组数目](../../problems/count-triplets-that-can-form-two-arrays-of-equal-xor) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1441 | [用栈操作构建数组](../../problems/build-an-array-with-stack-operations) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1439 | [有序矩阵中的第 k 个最小数组和](../../problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1438 | [绝对差不超过限制的最长连续子数组](../../problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1437 | [是否所有 1 都至少相隔 k 个元素](../../problems/check-if-all-1s-are-at-least-length-k-places-away) | [[数组](../array/README.md)]  | Easy |
-| 1434 | [每个人戴不同帽子的方案数](../../problems/number-of-ways-to-wear-different-hats-to-each-other) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1431 | [拥有最多糖果的孩子](../../problems/kids-with-the-greatest-number-of-candies) | [[数组](../array/README.md)]  | Easy |
-| 1429 | [第一个唯一数字](../../problems/first-unique-number) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1428 | [至少有一个 1 的最左端列](../../problems/leftmost-column-with-at-least-a-one) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1427 | [字符串的左右移](../../problems/perform-string-shifts) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1426 | [数元素](../../problems/counting-elements) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 1425 | [带限制的子序列和](../../problems/constrained-subsequence-sum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1424 | [对角线遍历 II](../../problems/diagonal-traverse-ii) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1423 | [可获得的最大点数](../../problems/maximum-points-you-can-obtain-from-cards) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1418 | [点菜展示表](../../problems/display-table-of-food-orders-in-a-restaurant) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1413 | [逐步求和得到正数的最小值](../../problems/minimum-value-to-get-positive-step-by-step-sum) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1409 | [查询带键的排列](../../problems/queries-on-a-permutation-with-key) | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1406 | [石子游戏 III](../../problems/stone-game-iii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1403 | [非递增顺序的最小子序列](../../problems/minimum-subsequence-in-non-increasing-order) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1402 | [做菜顺序](../../problems/reducing-dishes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1395 | [统计作战单位数](../../problems/count-number-of-teams) | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1394 | [找出数组中的幸运数](../../problems/find-lucky-integer-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1391 | [检查网格中是否存在有效路径](../../problems/check-if-there-is-a-valid-path-in-a-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1390 | [四因数](../../problems/four-divisors) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1389 | [按既定顺序创建目标数组](../../problems/create-target-array-in-the-given-order) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1388 | [3n 块披萨](../../problems/pizza-with-3n-slices) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1386 | [安排电影院座位](../../problems/cinema-seat-allocation) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1385 | [两个数组间的距离值](../../problems/find-the-distance-value-between-two-arrays) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1383 | [最大的团队表现值](../../problems/maximum-performance-of-a-team) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1381 | [设计一个支持增量操作的栈](../../problems/design-a-stack-with-increment-operation) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1380 | [矩阵中的幸运数](../../problems/lucky-numbers-in-a-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1375 | [二进制字符串前缀一致的次数](../../problems/number-of-times-binary-string-is-prefix-aligned) | [[数组](../array/README.md)]  | Medium |
-| 1368 | [使网格图至少有一条有效路径的最小代价](../../problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1366 | [通过投票对团队排名](../../problems/rank-teams-by-votes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1365 | [有多少小于当前数字的数字](../../problems/how-many-numbers-are-smaller-than-the-current-number) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1363 | [形成三的最大倍数](../../problems/largest-multiple-of-three) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1357 | [每隔 n 个顾客打折](../../problems/apply-discount-every-n-orders) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1356 | [根据数字二进制下 1 的数目排序](../../problems/sort-integers-by-the-number-of-1-bits) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1354 | [多次求和构造目标数组](../../problems/construct-target-array-with-multiple-sums) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1353 | [最多可以参加的会议数目](../../problems/maximum-number-of-events-that-can-be-attended) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1352 | [最后 K 个数的乘积](../../problems/product-of-the-last-k-numbers) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1351 | [统计有序矩阵中的负数](../../problems/count-negative-numbers-in-a-sorted-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1349 | [参加考试的最大学生数](../../problems/maximum-students-taking-exam) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1346 | [检查整数及其两倍数是否存在](../../problems/check-if-n-and-its-double-exist) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1345 | [跳跃游戏 IV](../../problems/jump-game-iv) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1343 | [大小为 K 且平均值大于等于阈值的子数组数目](../../problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1340 | [跳跃游戏 V](../../problems/jump-game-v) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1338 | [数组大小减半](../../problems/reduce-array-size-to-the-half) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1337 | [矩阵中战斗力最弱的 K 行](../../problems/the-k-weakest-rows-in-a-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 1335 | [工作计划的最低难度](../../problems/minimum-difficulty-of-a-job-schedule) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1333 | [餐厅过滤器](../../problems/filter-restaurants-by-vegan-friendly-price-and-distance) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1331 | [数组序号转换](../../problems/rank-transform-of-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1330 | [翻转子数组得到最大的数组值](../../problems/reverse-subarray-to-maximize-array-value) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1329 | [将矩阵按对角线排序](../../problems/sort-the-matrix-diagonally) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1326 | [灌溉花园的最少水龙头数目](../../problems/minimum-number-of-taps-to-open-to-water-a-garden) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1324 | [竖直打印单词](../../problems/print-words-vertically) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1314 | [矩阵区域和](../../problems/matrix-block-sum) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1313 | [解压缩编码列表](../../problems/decompress-run-length-encoded-list) | [[数组](../array/README.md)]  | Easy |
-| 1311 | [获取你好友已观看的视频](../../problems/get-watched-videos-by-your-friends) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1310 | [子数组异或查询](../../problems/xor-queries-of-a-subarray) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1307 | [口算难题](../../problems/verbal-arithmetic-puzzle) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1306 | [跳跃游戏 III](../../problems/jump-game-iii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1304 | [和为零的N个唯一整数](../../problems/find-n-unique-integers-sum-up-to-zero) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1301 | [最大得分的路径数目](../../problems/number-of-paths-with-max-score) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1300 | [转变数组后最接近目标值的数组和](../../problems/sum-of-mutated-array-closest-to-target) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1299 | [将每个元素替换为右侧最大元素](../../problems/replace-elements-with-greatest-element-on-right-side) | [[数组](../array/README.md)]  | Easy |
-| 1298 | [你能从盒子里获得的最大糖果数](../../problems/maximum-candies-you-can-get-from-boxes) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1296 | [划分数组为连续数字的集合](../../problems/divide-array-in-sets-of-k-consecutive-numbers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1295 | [统计位数为偶数的数字](../../problems/find-numbers-with-even-number-of-digits) | [[数组](../array/README.md)]  | Easy |
-| 1293 | [网格中的最短路径](../../problems/shortest-path-in-a-grid-with-obstacles-elimination) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1292 | [元素和小于等于阈值的正方形的最大边长](../../problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1289 | [下降路径最小和  II](../../problems/minimum-falling-path-sum-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1288 | [删除被覆盖区间](../../problems/remove-covered-intervals) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1287 | [有序数组中出现次数超过25%的元素](../../problems/element-appearing-more-than-25-in-sorted-array) | [[数组](../array/README.md)]  | Easy |
-| 1284 | [转化为全零矩阵的最少反转次数](../../problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1283 | [使结果不超过阈值的最小除数](../../problems/find-the-smallest-divisor-given-a-threshold) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1282 | [用户分组](../../problems/group-the-people-given-the-group-size-they-belong-to) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1277 | [统计全为 1 的正方形子矩阵](../../problems/count-square-submatrices-with-all-ones) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1275 | [找出井字棋的获胜者](../../problems/find-winner-on-a-tic-tac-toe-game) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1274 | [矩形内船只的数目](../../problems/number-of-ships-in-a-rectangle) 🔒 | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 1272 | [删除区间](../../problems/remove-interval) 🔒 | [[数组](../array/README.md)]  | Medium |
-| 1268 | [搜索推荐系统](../../problems/search-suggestions-system) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1267 | [统计参与通信的服务器](../../problems/count-servers-that-communicate) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1266 | [访问所有点的最小时间](../../problems/minimum-time-visiting-all-points) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1263 | [推箱子](../../problems/minimum-moves-to-move-a-box-to-their-target-location) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1262 | [可被三整除的最大和](../../problems/greatest-sum-divisible-by-three) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1260 | [二维网格迁移](../../problems/shift-2d-grid) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1258 | [近义词句子](../../problems/synonymous-sentences) 🔒 | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1257 | [最小公共区域](../../problems/smallest-common-region) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1255 | [得分最高的单词集合](../../problems/maximum-score-words-formed-by-letters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1254 | [统计封闭岛屿的数目](../../problems/number-of-closed-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1253 | [重构 2 行二进制矩阵](../../problems/reconstruct-a-2-row-binary-matrix) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1252 | [奇数值单元格的数目](../../problems/cells-with-odd-values-in-a-matrix) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1250 | [检查「好数组」](../../problems/check-if-it-is-a-good-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1248 | [统计「优美子数组」](../../problems/count-number-of-nice-subarrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1246 | [删除回文子数组](../../problems/palindrome-removal) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1243 | [数组变换](../../problems/array-transformation) 🔒 | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1239 | [串联字符串的最大长度](../../problems/maximum-length-of-a-concatenated-string-with-unique-characters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1235 | [规划兼职工作](../../problems/maximum-profit-in-job-scheduling) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1233 | [删除子文件夹](../../problems/remove-sub-folders-from-the-filesystem) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1232 | [缀点成线](../../problems/check-if-it-is-a-straight-line) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1231 | [分享巧克力](../../problems/divide-chocolate) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1229 | [安排会议日程](../../problems/meeting-scheduler) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1228 | [等差数列中缺失的数字](../../problems/missing-number-in-arithmetic-progression) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1224 | [最大相等频率](../../problems/maximum-equal-frequency) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1223 | [掷骰子模拟](../../problems/dice-roll-simulation) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1222 | [可以攻击国王的皇后](../../problems/queens-that-can-attack-the-king) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1219 | [黄金矿工](../../problems/path-with-maximum-gold) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1218 | [最长定差子序列](../../problems/longest-arithmetic-subsequence-of-given-difference) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1217 | [玩筹码](../../problems/minimum-cost-to-move-chips-to-the-same-position) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1213 | [三个有序数组的交集](../../problems/intersection-of-three-sorted-arrays) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1210 | [穿过迷宫的最少移动次数](../../problems/minimum-moves-to-reach-target-with-rotations) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1207 | [独一无二的出现次数](../../problems/unique-number-of-occurrences) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 1200 | [最小绝对差](../../problems/minimum-absolute-difference) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1198 | [找出所有行中最小公共元素](../../problems/find-smallest-common-element-in-all-rows) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1196 | [最多可以买到的苹果数量](../../problems/how-many-apples-can-you-put-into-the-basket) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1191 | [K 次串联后最大子数组之和](../../problems/k-concatenation-maximum-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1187 | [使数组严格递增](../../problems/make-array-strictly-increasing) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1186 | [删除一次得到子数组最大和](../../problems/maximum-subarray-sum-with-one-deletion) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1184 | [公交站间的距离](../../problems/distance-between-bus-stops) | [[数组](../array/README.md)]  | Easy |
-| 1182 | [与目标颜色间的最短距离](../../problems/shortest-distance-to-target-color) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1181 | [前后拼接](../../problems/before-and-after-puzzle) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1178 | [猜字谜](../../problems/number-of-valid-words-for-each-puzzle) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1176 | [健身计划评估](../../problems/diet-plan-performance) 🔒 | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1170 | [比较字符串最小字母出现频次](../../problems/compare-strings-by-frequency-of-the-smallest-character) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1169 | [查询无效交易](../../problems/invalid-transactions) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1167 | [连接棒材的最低费用](../../problems/minimum-cost-to-connect-sticks) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1162 | [地图分析](../../problems/as-far-from-land-as-possible) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1160 | [拼写单词](../../problems/find-words-that-can-be-formed-by-characters) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1157 | [子数组中占绝大多数的元素](../../problems/online-majority-element-in-subarray) | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1152 | [用户网站访问行为分析](../../problems/analyze-user-website-visit-pattern) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1151 | [最少交换次数来组合所有的 1](../../problems/minimum-swaps-to-group-all-1s-together) 🔒 | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1150 | [检查一个数是否在数组中占绝大多数](../../problems/check-if-a-number-is-majority-element-in-a-sorted-array) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 1146 | [快照数组](../../problems/snapshot-array) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1144 | [递减元素使数组呈锯齿状](../../problems/decrease-elements-to-make-array-zigzag) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1140 | [石子游戏 II](../../problems/stone-game-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1139 | [最大的以 1 为边界的正方形](../../problems/largest-1-bordered-square) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1133 | [最大唯一数](../../problems/largest-unique-number) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1131 | [绝对值表达式的最大值](../../problems/maximum-of-absolute-value-expression) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1128 | [等价多米诺骨牌对的数量](../../problems/number-of-equivalent-domino-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1125 | [最小的必要团队](../../problems/smallest-sufficient-team) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1124 | [表现良好的最长时间段](../../problems/longest-well-performing-interval) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1122 | [数组的相对排序](../../problems/relative-sort-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1121 | [将数组分成几个递增序列](../../problems/divide-array-into-increasing-sequences) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1109 | [航班预订统计](../../problems/corporate-flight-bookings) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1105 | [填充书架](../../problems/filling-bookcase-shelves) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1102 | [得分最高的路径](../../problems/path-with-maximum-minimum-value) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1101 | [彼此熟识的最早时间](../../problems/the-earliest-moment-when-everyone-become-friends) 🔒 | [[并查集](../union-find/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1099 | [小于 K 的两数之和](../../problems/two-sum-less-than-k) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1095 | [山脉数组中查找目标值](../../problems/find-in-mountain-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 1094 | [拼车](../../problems/car-pooling) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1091 | [二进制矩阵中的最短路径](../../problems/shortest-path-in-binary-matrix) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1090 | [受标签影响的最大值](../../problems/largest-values-from-labels) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1089 | [复写零](../../problems/duplicate-zeros) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 1086 | [前五科的均分](../../problems/high-five) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1085 | [最小元素各数位之和](../../problems/sum-of-digits-in-the-minimum-number) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1074 | [元素和为目标值的子矩阵数量](../../problems/number-of-submatrices-that-sum-to-target) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1073 | [负二进制数相加](../../problems/adding-two-negabinary-numbers) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1072 | [按列翻转得到最大值等行数](../../problems/flip-columns-for-maximum-number-of-equal-rows) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1066 | [校园自行车分配 II](../../problems/campus-bikes-ii) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1065 | [字符串的索引对](../../problems/index-pairs-of-a-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1064 | [不动点](../../problems/fixed-point) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 1063 | [有效子数组的数目](../../problems/number-of-valid-subarrays) 🔒 | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1060 | [有序数组中的缺失元素](../../problems/missing-element-in-sorted-array) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1058 | [最小化舍入误差以满足目标](../../problems/minimize-rounding-error-to-meet-target) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1057 | [校园自行车分配](../../problems/campus-bikes) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1054 | [距离相等的条形码](../../problems/distant-barcodes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1053 | [交换一次的先前排列](../../problems/previous-permutation-with-one-swap) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1052 | [爱生气的书店老板](../../problems/grumpy-bookstore-owner) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1051 | [高度检查器](../../problems/height-checker) | [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1049 | [最后一块石头的重量 II](../../problems/last-stone-weight-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1048 | [最长字符串链](../../problems/longest-string-chain) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1046 | [最后一块石头的重量](../../problems/last-stone-weight) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 1043 | [分隔数组以得到最大和](../../problems/partition-array-for-maximum-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1040 | [移动石子直到连续 II](../../problems/moving-stones-until-consecutive-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1039 | [多边形三角剖分的最低得分](../../problems/minimum-score-triangulation-of-polygon) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1036 | [逃离大迷宫](../../problems/escape-a-large-maze) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1035 | [不相交的线](../../problems/uncrossed-lines) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1034 | [边界着色](../../problems/coloring-a-border) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1032 | [字符流](../../problems/stream-of-characters) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[数据流](../data-stream/README.md)]  | Hard |
-| 1031 | [两个非重叠子数组的最大和](../../problems/maximum-sum-of-two-non-overlapping-subarrays) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1030 | [距离顺序排列矩阵单元格](../../problems/matrix-cells-in-distance-order) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1029 | [两地调度](../../problems/two-city-scheduling) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1027 | [最长等差数列](../../problems/longest-arithmetic-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1024 | [视频拼接](../../problems/video-stitching) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1020 | [飞地的数量](../../problems/number-of-enclaves) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1019 | [链表中的下一个更大节点](../../problems/next-greater-node-in-linked-list) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1018 | [可被 5 整除的二进制前缀](../../problems/binary-prefix-divisible-by-5) | [[数组](../array/README.md)]  | Easy |
-| 1014 | [最佳观光组合](../../problems/best-sightseeing-pair) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1013 | [将数组分成和相等的三个部分](../../problems/partition-array-into-three-parts-with-equal-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 1011 | [在 D 天内送达包裹的能力](../../problems/capacity-to-ship-packages-within-d-days) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1010 | [总持续时间可被 60 整除的歌曲](../../problems/pairs-of-songs-with-total-durations-divisible-by-60) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1008 | [前序遍历构造二叉搜索树](../../problems/construct-binary-search-tree-from-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1007 | [行相等的最少多米诺旋转](../../problems/minimum-domino-rotations-for-equal-row) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1005 | [K 次取反后最大化的数组和](../../problems/maximize-sum-of-array-after-k-negations) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1004 | [最大连续1的个数 III](../../problems/max-consecutive-ones-iii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1002 | [查找共用字符](../../problems/find-common-characters) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1001 | [网格照明](../../problems/grid-illumination) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1000 | [合并石头的最低成本](../../problems/minimum-cost-to-merge-stones) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 999 | [可以被一步捕获的棋子数](../../problems/available-captures-for-rook) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 997 | [找到小镇的法官](../../problems/find-the-town-judge) | [[图](../graph/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 996 | [正方形数组的数目](../../problems/number-of-squareful-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 995 | [K 连续位的最小翻转次数](../../problems/minimum-number-of-k-consecutive-bit-flips) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 994 | [腐烂的橘子](../../problems/rotting-oranges) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 992 | [K 个不同整数的子数组](../../problems/subarrays-with-k-different-integers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 990 | [等式方程的可满足性](../../problems/satisfiability-of-equality-equations) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 989 | [数组形式的整数加法](../../problems/add-to-array-form-of-integer) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 986 | [区间列表的交集](../../problems/interval-list-intersections) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 985 | [查询后的偶数和](../../problems/sum-of-even-numbers-after-queries) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 983 | [最低票价](../../problems/minimum-cost-for-tickets) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 982 | [按位与为零的三元组](../../problems/triples-with-bitwise-and-equal-to-zero) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 980 | [不同路径 III](../../problems/unique-paths-iii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 978 | [最长湍流子数组](../../problems/longest-turbulent-subarray) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 977 | [有序数组的平方](../../problems/squares-of-a-sorted-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 976 | [三角形的最大周长](../../problems/largest-perimeter-triangle) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 975 | [奇偶跳](../../problems/odd-even-jump) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 974 | [和可被 K 整除的子数组](../../problems/subarray-sums-divisible-by-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 973 | [最接近原点的 K 个点](../../problems/k-closest-points-to-origin) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 969 | [煎饼排序](../../problems/pancake-sorting) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 966 | [元音拼写检查器](../../problems/vowel-spellchecker) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 963 | [最小面积矩形 II](../../problems/minimum-area-rectangle-ii) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 962 | [最大宽度坡](../../problems/maximum-width-ramp) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 961 | [在长度 2N 的数组中找出重复 N 次的元素](../../problems/n-repeated-element-in-size-2n-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 960 | [删列造序 III](../../problems/delete-columns-to-make-sorted-iii) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 957 | [N 天后的牢房](../../problems/prison-cells-after-n-days) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 956 | [最高的广告牌](../../problems/tallest-billboard) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 955 | [删列造序 II](../../problems/delete-columns-to-make-sorted-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 954 | [二倍数对数组](../../problems/array-of-doubled-pairs) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 953 | [验证外星语词典](../../problems/verifying-an-alien-dictionary) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 952 | [按公因数计算最大组件大小](../../problems/largest-component-size-by-common-factor) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 950 | [按递增顺序显示卡牌](../../problems/reveal-cards-in-increasing-order) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 948 | [令牌放置](../../problems/bag-of-tokens) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 946 | [验证栈序列](../../problems/validate-stack-sequences) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 945 | [使数组唯一的最小增量](../../problems/minimum-increment-to-make-array-unique) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 944 | [删列造序](../../problems/delete-columns-to-make-sorted) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 943 | [最短超级串](../../problems/find-the-shortest-superstring) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 942 | [增减字符串匹配](../../problems/di-string-match) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 941 | [有效的山脉数组](../../problems/valid-mountain-array) | [[数组](../array/README.md)]  | Easy |
-| 939 | [最小面积矩形](../../problems/minimum-area-rectangle) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 937 | [重新排列日志文件](../../problems/reorder-data-in-log-files) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 934 | [最短的桥](../../problems/shortest-bridge) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 932 | [漂亮数组](../../problems/beautiful-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)]  | Medium |
-| 931 | [下降路径最小和](../../problems/minimum-falling-path-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 930 | [和相同的二元子数组](../../problems/binary-subarrays-with-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 929 | [独特的电子邮件地址](../../problems/unique-email-addresses) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 928 | [尽量减少恶意软件的传播 II](../../problems/minimize-malware-spread-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 927 | [三等分](../../problems/three-equal-parts) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 924 | [尽量减少恶意软件的传播](../../problems/minimize-malware-spread) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 923 | [三数之和的多种可能](../../problems/3sum-with-multiplicity) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 922 | [按奇偶排序数组 II](../../problems/sort-array-by-parity-ii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 918 | [环形子数组的最大和](../../problems/maximum-sum-circular-subarray) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Medium |
-| 916 | [单词子集](../../problems/word-subsets) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 915 | [分割数组](../../problems/partition-array-into-disjoint-intervals) | [[数组](../array/README.md)]  | Medium |
-| 914 | [卡牌分组](../../problems/x-of-a-kind-in-a-deck-of-cards) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Easy |
-| 912 | [排序数组](../../problems/sort-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数排序](../counting-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 911 | [在线选举](../../problems/online-election) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 910 | [最小差值 II](../../problems/smallest-range-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 909 | [蛇梯棋](../../problems/snakes-and-ladders) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 908 | [最小差值 I](../../problems/smallest-range-i) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 907 | [子数组的最小值之和](../../problems/sum-of-subarray-minimums) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 905 | [按奇偶排序数组](../../problems/sort-array-by-parity) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 904 | [水果成篮](../../problems/fruit-into-baskets) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 902 | [最大为 N 的数字组合](../../problems/numbers-at-most-n-given-digit-set) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 900 | [RLE 迭代器](../../problems/rle-iterator) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 898 | [子数组按位或操作](../../problems/bitwise-ors-of-subarrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 896 | [单调数列](../../problems/monotonic-array) | [[数组](../array/README.md)]  | Easy |
-| 893 | [特殊等价字符串组](../../problems/groups-of-special-equivalent-strings) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 892 | [三维形体的表面积](../../problems/surface-area-of-3d-shapes) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 891 | [子序列宽度之和](../../problems/sum-of-subsequence-widths) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 890 | [查找和替换模式](../../problems/find-and-replace-pattern) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 889 | [根据前序和后序遍历构造二叉树](../../problems/construct-binary-tree-from-preorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 888 | [公平的糖果交换](../../problems/fair-candy-swap) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 885 | [螺旋矩阵 III](../../problems/spiral-matrix-iii) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 883 | [三维形体投影面积](../../problems/projection-area-of-3d-shapes) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 881 | [救生艇](../../problems/boats-to-save-people) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 879 | [盈利计划](../../problems/profitable-schemes) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 877 | [石子游戏](../../problems/stone-game) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 875 | [爱吃香蕉的珂珂](../../problems/koko-eating-bananas) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 874 | [模拟行走机器人](../../problems/walking-robot-simulation) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 873 | [最长的斐波那契子序列的长度](../../problems/length-of-longest-fibonacci-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 871 | [最低加油次数](../../problems/minimum-number-of-refueling-stops) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 870 | [优势洗牌](../../problems/advantage-shuffle) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 867 | [转置矩阵](../../problems/transpose-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 862 | [和至少为 K 的最短子数组](../../problems/shortest-subarray-with-sum-at-least-k) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 861 | [翻转矩阵后的得分](../../problems/score-after-flipping-matrix) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 860 | [柠檬水找零](../../problems/lemonade-change) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 857 | [雇佣 K 名工人的最低成本](../../problems/minimum-cost-to-hire-k-workers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 853 | [车队](../../problems/car-fleet) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 852 | [山脉数组的峰顶索引](../../problems/peak-index-in-a-mountain-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 851 | [喧闹和富有](../../problems/loud-and-rich) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)]  | Medium |
-| 850 | [矩形面积 II](../../problems/rectangle-area-ii) | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)]  | Hard |
-| 849 | [到最近的人的最大距离](../../problems/maximize-distance-to-closest-person) | [[数组](../array/README.md)]  | Medium |
-| 848 | [字母移位](../../problems/shifting-letters) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 846 | [一手顺子](../../problems/hand-of-straights) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 845 | [数组中的最长山脉](../../problems/longest-mountain-in-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 843 | [猜猜这个单词](../../problems/guess-the-word) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[博弈](../game-theory/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 840 | [矩阵中的幻方](../../problems/magic-squares-in-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 835 | [图像重叠](../../problems/image-overlap) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 833 | [字符串中的查找与替换](../../problems/find-and-replace-in-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 832 | [翻转图像](../../problems/flipping-an-image) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 827 | [最大人工岛](../../problems/making-a-large-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 826 | [安排工作以达到最大收益](../../problems/most-profit-assigning-work) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 825 | [适龄的朋友](../../problems/friends-of-appropriate-ages) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 823 | [带因子的二叉树](../../problems/binary-trees-with-factors) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 822 | [翻转卡片游戏](../../problems/card-flipping-game) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 821 | [字符的最短距离](../../problems/shortest-distance-to-a-character) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 820 | [单词的压缩编码](../../problems/short-encoding-of-words) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 815 | [公交路线](../../problems/bus-routes) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 813 | [最大平均值和的分组](../../problems/largest-sum-of-averages) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 812 | [最大三角形面积](../../problems/largest-triangle-area) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 811 | [子域名访问计数](../../problems/subdomain-visit-count) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 810 | [黑板异或游戏](../../problems/chalkboard-xor-game) | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 809 | [情感丰富的文字](../../problems/expressive-words) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 807 | [保持城市天际线](../../problems/max-increase-to-keep-city-skyline) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 806 | [写字符串需要的行数](../../problems/number-of-lines-to-write-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 805 | [数组的均值分割](../../problems/split-array-with-same-average) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 804 | [唯一摩尔斯密码词](../../problems/unique-morse-code-words) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 803 | [打砖块](../../problems/bricks-falling-when-hit) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 801 | [使序列递增的最小交换次数](../../problems/minimum-swaps-to-make-sequences-increasing) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 798 | [得分最高的最小轮调](../../problems/smallest-rotation-with-highest-score) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 795 | [区间子数组个数](../../problems/number-of-subarrays-with-bounded-maximum) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 794 | [有效的井字游戏](../../problems/valid-tic-tac-toe-state) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 789 | [逃脱阻碍者](../../problems/escape-the-ghosts) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 786 | [第 K 个最小的素数分数](../../problems/k-th-smallest-prime-fraction) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 782 | [变为棋盘](../../problems/transform-to-chessboard) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 781 | [森林中的兔子](../../problems/rabbits-in-forest) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 778 | [水位上升的泳池中游泳](../../problems/swim-in-rising-water) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 775 | [全局倒置与局部倒置](../../problems/global-and-local-inversions) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 774 | [最小化去加油站的最大距离](../../problems/minimize-max-distance-to-gas-station) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 773 | [滑动谜题](../../problems/sliding-puzzle) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 769 | [最多能完成排序的块](../../problems/max-chunks-to-make-sorted) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 768 | [最多能完成排序的块 II](../../problems/max-chunks-to-make-sorted-ii) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 766 | [托普利茨矩阵](../../problems/toeplitz-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 764 | [最大加号标志](../../problems/largest-plus-sign) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 760 | [找出变位映射](../../problems/find-anagram-mappings) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 759 | [员工空闲时间](../../problems/employee-free-time) 🔒 | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 758 | [字符串中的加粗单词](../../problems/bold-words-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 757 | [设置交集大小至少为2](../../problems/set-intersection-size-at-least-two) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 755 | [倒水](../../problems/pour-water) 🔒 | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 752 | [打开转盘锁](../../problems/open-the-lock) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 750 | [角矩形的数量](../../problems/number-of-corner-rectangles) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 749 | [隔离病毒](../../problems/contain-virus) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 748 | [最短补全词](../../problems/shortest-completing-word) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 747 | [至少是其他数字两倍的最大数](../../problems/largest-number-at-least-twice-of-others) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 746 | [使用最小花费爬楼梯](../../problems/min-cost-climbing-stairs) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 744 | [寻找比目标字母大的最小字母](../../problems/find-smallest-letter-greater-than-target) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 741 | [摘樱桃](../../problems/cherry-pickup) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 740 | [删除并获得点数](../../problems/delete-and-earn) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 739 | [每日温度](../../problems/daily-temperatures) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 737 | [句子相似性 II](../../problems/sentence-similarity-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 735 | [行星碰撞](../../problems/asteroid-collision) | [[栈](../stack/README.md)] [[数组](../array/README.md)]  | Medium |
-| 734 | [句子相似性](../../problems/sentence-similarity) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 733 | [图像渲染](../../problems/flood-fill) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 724 | [寻找数组的中心下标](../../problems/find-pivot-index) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 723 | [粉碎糖果](../../problems/candy-crush) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 722 | [删除注释](../../problems/remove-comments) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 721 | [账户合并](../../problems/accounts-merge) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 720 | [词典中最长的单词](../../problems/longest-word-in-dictionary) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 719 | [找出第 k 小的距离对](../../problems/find-k-th-smallest-pair-distance) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 718 | [最长重复子数组](../../problems/maximum-length-of-repeated-subarray) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 717 | [1比特与2比特字符](../../problems/1-bit-and-2-bit-characters) | [[数组](../array/README.md)]  | Easy |
-| 714 | [买卖股票的最佳时机含手续费](../../problems/best-time-to-buy-and-sell-stock-with-transaction-fee) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 713 | [乘积小于K的子数组](../../problems/subarray-product-less-than-k) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 706 | [设计哈希映射](../../problems/design-hashmap) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 705 | [设计哈希集合](../../problems/design-hashset) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 704 | [二分查找](../../problems/binary-search) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 702 | [搜索长度未知的有序数组](../../problems/search-in-a-sorted-array-of-unknown-size) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 699 | [掉落的方块](../../problems/falling-squares) | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 698 | [划分为k个相等的子集](../../problems/partition-to-k-equal-sum-subsets) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 697 | [数组的度](../../problems/degree-of-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 695 | [岛屿的最大面积](../../problems/max-area-of-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 689 | [三个无重叠子数组的最大和](../../problems/maximum-sum-of-3-non-overlapping-subarrays) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 683 | [K 个关闭的灯泡](../../problems/k-empty-slots) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 682 | [棒球比赛](../../problems/baseball-game) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 679 | [24 点游戏](../../problems/24-game) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 675 | [为高尔夫比赛砍树](../../problems/cut-off-trees-for-golf-event) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 674 | [最长连续递增序列](../../problems/longest-continuous-increasing-subsequence) | [[数组](../array/README.md)]  | Easy |
-| 673 | [最长递增子序列的个数](../../problems/number-of-longest-increasing-subsequence) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 667 | [优美的排列 II](../../problems/beautiful-arrangement-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 666 | [路径总和 IV](../../problems/path-sum-iv) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 665 | [非递减数列](../../problems/non-decreasing-array) | [[数组](../array/README.md)]  | Medium |
-| 661 | [图片平滑器](../../problems/image-smoother) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 659 | [分割数组为连续子序列](../../problems/split-array-into-consecutive-subsequences) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 658 | [找到 K 个最接近的元素](../../problems/find-k-closest-elements) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 656 | [金币路径](../../problems/coin-path) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 654 | [最大二叉树](../../problems/maximum-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 648 | [单词替换](../../problems/replace-words) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 646 | [最长数对链](../../problems/maximum-length-of-pair-chain) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 645 | [错误的集合](../../problems/set-mismatch) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 644 | [子数组最大平均数 II](../../problems/maximum-average-subarray-ii) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 643 | [子数组最大平均数 I](../../problems/maximum-average-subarray-i) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 641 | [设计循环双端队列](../../problems/design-circular-deque) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 638 | [大礼包](../../problems/shopping-offers) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 636 | [函数的独占时间](../../problems/exclusive-time-of-functions) | [[栈](../stack/README.md)] [[数组](../array/README.md)]  | Medium |
-| 632 | [最小区间](../../problems/smallest-range-covering-elements-from-k-lists) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 630 | [课程表 III](../../problems/course-schedule-iii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 628 | [三个数的最大乘积](../../problems/maximum-product-of-three-numbers) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 624 | [数组列表中的最大距离](../../problems/maximum-distance-in-arrays) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 622 | [设计循环队列](../../problems/design-circular-queue) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 621 | [任务调度器](../../problems/task-scheduler) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 616 | [给字符串添加加粗标签](../../problems/add-bold-tag-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 611 | [有效三角形的个数](../../problems/valid-triangle-number) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 609 | [在系统中查找重复文件](../../problems/find-duplicate-file-in-system) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 605 | [种花问题](../../problems/can-place-flowers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 604 | [迭代压缩字符串](../../problems/design-compressed-string-iterator) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[迭代器](../iterator/README.md)]  | Easy |
-| 599 | [两个列表的最小索引总和](../../problems/minimum-index-sum-of-two-lists) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 598 | [范围求和 II](../../problems/range-addition-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 594 | [最长和谐子序列](../../problems/longest-harmonious-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 587 | [安装栅栏](../../problems/erect-the-fence) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 582 | [杀掉进程](../../problems/kill-process) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 581 | [最短无序连续子数组](../../problems/shortest-unsorted-continuous-subarray) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 575 | [分糖果](../../problems/distribute-candies) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 573 | [松鼠模拟](../../problems/squirrel-simulation) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 568 | [最大休假天数](../../problems/maximum-vacation-days) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 566 | [重塑矩阵](../../problems/reshape-the-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 565 | [数组嵌套](../../problems/array-nesting) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)]  | Medium |
-| 562 | [矩阵中最长的连续1线段](../../problems/longest-line-of-consecutive-one-in-matrix) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 561 | [数组拆分 I](../../problems/array-partition-i) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 560 | [和为 K 的子数组](../../problems/subarray-sum-equals-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 555 | [分割连接字符串](../../problems/split-concatenated-strings) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 554 | [砖墙](../../problems/brick-wall) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 553 | [最优除法](../../problems/optimal-division) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 548 | [将数组分割成和相等的子数组](../../problems/split-array-with-equal-sum) 🔒 | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 546 | [移除盒子](../../problems/remove-boxes) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 542 | [01 矩阵](../../problems/01-matrix) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 540 | [有序数组中的单一元素](../../problems/single-element-in-a-sorted-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 539 | [最小时间差](../../problems/minimum-time-difference) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 533 | [孤独像素 II](../../problems/lonely-pixel-ii) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 532 | [数组中的 k-diff 数对](../../problems/k-diff-pairs-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 531 | [孤独像素 I](../../problems/lonely-pixel-i) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 529 | [扫雷游戏](../../problems/minesweeper) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 527 | [单词缩写](../../problems/word-abbreviation) 🔒 | [[贪心](../greedy/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 526 | [优美的排列](../../problems/beautiful-arrangement) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 525 | [连续数组](../../problems/contiguous-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 524 | [通过删除字母匹配到字典里最长单词](../../problems/longest-word-in-dictionary-through-deleting) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 523 | [连续的子数组和](../../problems/continuous-subarray-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 522 | [最长特殊序列 II](../../problems/longest-uncommon-subsequence-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 518 | [零钱兑换 II](../../problems/coin-change-2) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 517 | [超级洗衣机](../../problems/super-washing-machines) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Hard |
-| 506 | [相对名次](../../problems/relative-ranks) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 503 | [下一个更大元素 II](../../problems/next-greater-element-ii) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 502 | [IPO](../../problems/ipo) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 500 | [键盘行](../../problems/keyboard-row) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 498 | [对角线遍历](../../problems/diagonal-traverse) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 496 | [下一个更大元素 I](../../problems/next-greater-element-i) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Easy |
-| 495 | [提莫攻击](../../problems/teemo-attacking) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 494 | [目标和](../../problems/target-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 493 | [翻转对](../../problems/reverse-pairs) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 491 | [递增子序列](../../problems/increasing-subsequences) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 487 | [最大连续1的个数 II](../../problems/max-consecutive-ones-ii) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 486 | [预测赢家](../../problems/predict-the-winner) | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 485 | [最大连续 1 的个数](../../problems/max-consecutive-ones) | [[数组](../array/README.md)]  | Easy |
-| 484 | [寻找排列](../../problems/find-permutation) 🔒 | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 480 | [滑动窗口中位数](../../problems/sliding-window-median) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 477 | [汉明距离总和](../../problems/total-hamming-distance) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 475 | [供暖器](../../problems/heaters) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 474 | [一和零](../../problems/ones-and-zeroes) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 473 | [火柴拼正方形](../../problems/matchsticks-to-square) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 472 | [连接词](../../problems/concatenated-words) | [[深度优先搜索](../depth-first-search/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 465 | [最优账单平衡](../../problems/optimal-account-balancing) 🔒 | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 463 | [岛屿的周长](../../problems/island-perimeter) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 462 | [最少移动次数使数组元素相等 II](../../problems/minimum-moves-to-equal-array-elements-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 457 | [环形数组是否存在循环](../../problems/circular-array-loop) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 456 | [132 模式](../../problems/132-pattern) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 455 | [分发饼干](../../problems/assign-cookies) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 454 | [四数相加 II](../../problems/4sum-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 453 | [最小操作次数使数组元素相等](../../problems/minimum-moves-to-equal-array-elements) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 452 | [用最少数量的箭引爆气球](../../problems/minimum-number-of-arrows-to-burst-balloons) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 448 | [找到所有数组中消失的数字](../../problems/find-all-numbers-disappeared-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 447 | [回旋镖的数量](../../problems/number-of-boomerangs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 446 | [等差数列划分 II - 子序列](../../problems/arithmetic-slices-ii-subsequence) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 444 | [序列重建](../../problems/sequence-reconstruction) 🔒 | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)]  | Medium |
-| 442 | [数组中重复的数据](../../problems/find-all-duplicates-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 436 | [寻找右区间](../../problems/find-right-interval) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 435 | [无重叠区间](../../problems/non-overlapping-intervals) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 427 | [建立四叉树](../../problems/construct-quad-tree) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 425 | [单词方块](../../problems/word-squares) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 422 | [有效的单词方块](../../problems/valid-word-square) 🔒 | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 421 | [数组中两个数的最大异或值](../../problems/maximum-xor-of-two-numbers-in-an-array) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 419 | [甲板上的战舰](../../problems/battleships-in-a-board) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 417 | [太平洋大西洋水流问题](../../problems/pacific-atlantic-water-flow) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 416 | [分割等和子集](../../problems/partition-equal-subset-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 414 | [第三大的数](../../problems/third-maximum-number) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 413 | [等差数列划分](../../problems/arithmetic-slices) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 410 | [分割数组的最大值](../../problems/split-array-largest-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 407 | [接雨水 II](../../problems/trapping-rain-water-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 406 | [根据身高重建队列](../../problems/queue-reconstruction-by-height) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 403 | [青蛙过河](../../problems/frog-jump) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 399 | [除法求值](../../problems/evaluate-division) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 393 | [UTF-8 编码验证](../../problems/utf-8-validation) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Medium |
-| 391 | [完美矩形](../../problems/perfect-rectangle) | [[数组](../array/README.md)] [[扫描线](../line-sweep/README.md)]  | Hard |
-| 384 | [打乱数组](../../problems/shuffle-an-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 381 | [O(1) 时间插入、删除和获取随机元素 - 允许重复](../../problems/insert-delete-getrandom-o1-duplicates-allowed) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 380 | [O(1) 时间插入、删除和获取随机元素](../../problems/insert-delete-getrandom-o1) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 379 | [电话目录管理系统](../../problems/design-phone-directory) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 378 | [有序矩阵中第 K 小的元素](../../problems/kth-smallest-element-in-a-sorted-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 377 | [组合总和 Ⅳ](../../problems/combination-sum-iv) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 376 | [摆动序列](../../problems/wiggle-subsequence) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 373 | [查找和最小的 K 对数字](../../problems/find-k-pairs-with-smallest-sums) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 370 | [区间加法](../../problems/range-addition) 🔒 | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 368 | [最大整除子集](../../problems/largest-divisible-subset) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 363 | [矩形区域不超过 K 的最大数值和](../../problems/max-sum-of-rectangle-no-larger-than-k) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 362 | [敲击计数器](../../problems/design-hit-counter) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 361 | [轰炸敌人](../../problems/bomb-enemy) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 360 | [有序转化数组](../../problems/sort-transformed-array) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 356 | [直线镜像](../../problems/line-reflection) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 354 | [俄罗斯套娃信封问题](../../problems/russian-doll-envelopes) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 353 | [贪吃蛇](../../problems/design-snake-game) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 350 | [两个数组的交集 II](../../problems/intersection-of-two-arrays-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 349 | [两个数组的交集](../../problems/intersection-of-two-arrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 348 | [设计井字棋](../../problems/design-tic-tac-toe) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 347 | [前 K 个高频元素](../../problems/top-k-frequent-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 346 | [数据流中的移动平均值](../../problems/moving-average-from-data-stream) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 336 | [回文对](../../problems/palindrome-pairs) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 335 | [路径交叉](../../problems/self-crossing) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 334 | [递增的三元子序列](../../problems/increasing-triplet-subsequence) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 330 | [按要求补齐数组](../../problems/patching-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Hard |
-| 327 | [区间和的个数](../../problems/count-of-range-sum) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 325 | [和等于 k 的最长子数组长度](../../problems/maximum-size-subarray-sum-equals-k) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 324 | [摆动排序 II](../../problems/wiggle-sort-ii) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 322 | [零钱兑换](../../problems/coin-change) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 318 | [最大单词长度乘积](../../problems/maximum-product-of-word-lengths) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 317 | [离建筑物最近的距离](../../problems/shortest-distance-from-all-buildings) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 315 | [计算右侧小于当前元素的个数](../../problems/count-of-smaller-numbers-after-self) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 313 | [超级丑数](../../problems/super-ugly-number) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 312 | [戳气球](../../problems/burst-balloons) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 311 | [稀疏矩阵的乘法](../../problems/sparse-matrix-multiplication) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 309 | [最佳买卖股票时机含冷冻期](../../problems/best-time-to-buy-and-sell-stock-with-cooldown) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 308 | [二维区域和检索 - 可变](../../problems/range-sum-query-2d-mutable) 🔒 | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 307 | [区域和检索 - 数组可修改](../../problems/range-sum-query-mutable) | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)]  | Medium |
-| 305 | [岛屿数量 II](../../problems/number-of-islands-ii) 🔒 | [[并查集](../union-find/README.md)] [[数组](../array/README.md)]  | Hard |
-| 304 | [二维区域和检索 - 矩阵不可变](../../problems/range-sum-query-2d-immutable) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 303 | [区域和检索 - 数组不可变](../../problems/range-sum-query-immutable) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 302 | [包含全部黑色像素的最小矩形](../../problems/smallest-rectangle-enclosing-black-pixels) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 300 | [最长递增子序列](../../problems/longest-increasing-subsequence) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 296 | [最佳的碰头地点](../../problems/best-meeting-point) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 289 | [生命游戏](../../problems/game-of-life) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 288 | [单词的唯一缩写](../../problems/unique-word-abbreviation) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 287 | [寻找重复数](../../problems/find-the-duplicate-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 286 | [墙与门](../../problems/walls-and-gates) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 284 | [顶端迭代器](../../problems/peeking-iterator) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 283 | [移动零](../../problems/move-zeroes) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 281 | [锯齿迭代器](../../problems/zigzag-iterator) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 280 | [摆动排序](../../problems/wiggle-sort) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 275 | [H 指数 II](../../problems/h-index-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 274 | [H 指数](../../problems/h-index) | [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 271 | [字符串的编码与解码](../../problems/encode-and-decode-strings) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 269 | [火星词典](../../problems/alien-dictionary) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 268 | [丢失的数字](../../problems/missing-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 265 | [粉刷房子 II](../../problems/paint-house-ii) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 260 | [只出现一次的数字 III](../../problems/single-number-iii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Medium |
-| 259 | [较小的三数之和](../../problems/3sum-smaller) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 256 | [粉刷房子](../../problems/paint-house) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 254 | [因子的组合](../../problems/factor-combinations) 🔒 | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 253 | [会议室 II](../../problems/meeting-rooms-ii) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 252 | [会议室](../../problems/meeting-rooms) 🔒 | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 251 | [展开二维向量](../../problems/flatten-2d-vector) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 249 | [移位字符串分组](../../problems/group-shifted-strings) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 248 | [中心对称数 III](../../problems/strobogrammatic-number-iii) 🔒 | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 247 | [中心对称数 II](../../problems/strobogrammatic-number-ii) 🔒 | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 245 | [最短单词距离 III](../../problems/shortest-word-distance-iii) 🔒 | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 244 | [最短单词距离 II](../../problems/shortest-word-distance-ii) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 243 | [最短单词距离](../../problems/shortest-word-distance) 🔒 | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 240 | [搜索二维矩阵 II](../../problems/search-a-2d-matrix-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 239 | [滑动窗口最大值](../../problems/sliding-window-maximum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 238 | [除自身以外数组的乘积](../../problems/product-of-array-except-self) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 229 | [求众数 II](../../problems/majority-element-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 228 | [汇总区间](../../problems/summary-ranges) | [[数组](../array/README.md)]  | Easy |
-| 221 | [最大正方形](../../problems/maximal-square) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 220 | [存在重复元素 III](../../problems/contains-duplicate-iii) | [[数组](../array/README.md)] [[桶排序](../bucket-sort/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 219 | [存在重复元素 II](../../problems/contains-duplicate-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 218 | [天际线问题](../../problems/the-skyline-problem) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 217 | [存在重复元素](../../problems/contains-duplicate) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 216 | [组合总和 III](../../problems/combination-sum-iii) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 215 | [数组中的第K个最大元素](../../problems/kth-largest-element-in-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 213 | [打家劫舍 II](../../problems/house-robber-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 212 | [单词搜索 II](../../problems/word-search-ii) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 209 | [长度最小的子数组](../../problems/minimum-size-subarray-sum) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 204 | [计数质数](../../problems/count-primes) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[枚举](../enumeration/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 200 | [岛屿数量](../../problems/number-of-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 198 | [打家劫舍](../../problems/house-robber) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 189 | [轮转数组](../../problems/rotate-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 188 | [买卖股票的最佳时机 IV](../../problems/best-time-to-buy-and-sell-stock-iv) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 174 | [地下城游戏](../../problems/dungeon-game) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 170 | [两数之和 III - 数据结构设计](../../problems/two-sum-iii-data-structure-design) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 169 | [多数元素](../../problems/majority-element) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 167 | [两数之和 II - 输入有序数组](../../problems/two-sum-ii-input-array-is-sorted) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 164 | [最大间距](../../problems/maximum-gap) | [[数组](../array/README.md)] [[桶排序](../bucket-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 163 | [缺失的区间](../../problems/missing-ranges) 🔒 | [[数组](../array/README.md)]  | Easy |
-| 162 | [寻找峰值](../../problems/find-peak-element) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 154 | [寻找旋转排序数组中的最小值 II](../../problems/find-minimum-in-rotated-sorted-array-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 153 | [寻找旋转排序数组中的最小值](../../problems/find-minimum-in-rotated-sorted-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 152 | [乘积最大子数组](../../problems/maximum-product-subarray) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 150 | [逆波兰表达式求值](../../problems/evaluate-reverse-polish-notation) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 149 | [直线上最多的点数](../../problems/max-points-on-a-line) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Hard |
-| 137 | [只出现一次的数字 II](../../problems/single-number-ii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Medium |
-| 136 | [只出现一次的数字](../../problems/single-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Easy |
-| 135 | [分发糖果](../../problems/candy) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Hard |
-| 134 | [加油站](../../problems/gas-station) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 130 | [被围绕的区域](../../problems/surrounded-regions) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 128 | [最长连续序列](../../problems/longest-consecutive-sequence) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 123 | [买卖股票的最佳时机 III](../../problems/best-time-to-buy-and-sell-stock-iii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 122 | [买卖股票的最佳时机 II](../../problems/best-time-to-buy-and-sell-stock-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 121 | [买卖股票的最佳时机](../../problems/best-time-to-buy-and-sell-stock) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 120 | [三角形最小路径和](../../problems/triangle) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 119 | [杨辉三角 II](../../problems/pascals-triangle-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 118 | [杨辉三角](../../problems/pascals-triangle) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 108 | [将有序数组转换为二叉搜索树](../../problems/convert-sorted-array-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 106 | [从中序与后序遍历序列构造二叉树](../../problems/construct-binary-tree-from-inorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 105 | [从前序与中序遍历序列构造二叉树](../../problems/construct-binary-tree-from-preorder-and-inorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 90 | [子集 II](../../problems/subsets-ii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 88 | [合并两个有序数组](../../problems/merge-sorted-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 85 | [最大矩形](../../problems/maximal-rectangle) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 84 | [柱状图中最大的矩形](../../problems/largest-rectangle-in-histogram) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 81 | [搜索旋转排序数组 II](../../problems/search-in-rotated-sorted-array-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 80 | [删除有序数组中的重复项 II](../../problems/remove-duplicates-from-sorted-array-ii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 79 | [单词搜索](../../problems/word-search) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 78 | [子集](../../problems/subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 77 | [组合](../../problems/combinations) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 75 | [颜色分类](../../problems/sort-colors) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 74 | [搜索二维矩阵](../../problems/search-a-2d-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 73 | [矩阵置零](../../problems/set-matrix-zeroes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 66 | [加一](../../problems/plus-one) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 64 | [最小路径和](../../problems/minimum-path-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 63 | [不同路径 II](../../problems/unique-paths-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 59 | [螺旋矩阵 II](../../problems/spiral-matrix-ii) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 57 | [插入区间](../../problems/insert-interval) | [[数组](../array/README.md)]  | Medium |
-| 56 | [合并区间](../../problems/merge-intervals) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 55 | [跳跃游戏](../../problems/jump-game) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 54 | [螺旋矩阵](../../problems/spiral-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 53 | [最大子数组和](../../problems/maximum-subarray) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 51 | [N 皇后](../../problems/n-queens) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 48 | [旋转图像](../../problems/rotate-image) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 47 | [全排列 II](../../problems/permutations-ii) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 46 | [全排列](../../problems/permutations) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 45 | [跳跃游戏 II](../../problems/jump-game-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 42 | [接雨水](../../problems/trapping-rain-water) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 41 | [缺失的第一个正数](../../problems/first-missing-positive) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 40 | [组合总和 II](../../problems/combination-sum-ii) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 39 | [组合总和](../../problems/combination-sum) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 37 | [解数独](../../problems/sudoku-solver) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 36 | [有效的数独](../../problems/valid-sudoku) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 35 | [搜索插入位置](../../problems/search-insert-position) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 34 | [在排序数组中查找元素的第一个和最后一个位置](../../problems/find-first-and-last-position-of-element-in-sorted-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 33 | [搜索旋转排序数组](../../problems/search-in-rotated-sorted-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 31 | [下一个排列](../../problems/next-permutation) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 27 | [移除元素](../../problems/remove-element) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 26 | [删除有序数组中的重复项](../../problems/remove-duplicates-from-sorted-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 18 | [四数之和](../../problems/4sum) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 16 | [最接近的三数之和](../../problems/3sum-closest) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 15 | [三数之和](../../problems/3sum) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 11 | [盛最多水的容器](../../problems/container-with-most-water) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 4 | [寻找两个正序数组的中位数](../../problems/median-of-two-sorted-arrays) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)]  | Hard |
-| 1 | [两数之和](../../problems/two-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
diff --git a/tag/backtracking/README.md b/tag/backtracking/README.md
deleted file mode 100644
index 88a033751..000000000
--- a/tag/backtracking/README.md
+++ /dev/null
@@ -1,101 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 回溯
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2152 | [Minimum Number of Lines to Cover Points](../../problems/minimum-number-of-lines-to-cover-points) 🔒 | [[位运算](../bit-manipulation/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 2151 | [基于陈述统计最多好人数](../../problems/maximum-good-people-based-on-statements) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2065 | [最大化一张图中的路径价值](../../problems/maximum-path-quality-of-a-graph) | [[图](../graph/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 2056 | [棋盘上有效移动组合的数目](../../problems/number-of-valid-move-combinations-on-chessboard) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 2048 | [下一个更大的数值平衡数](../../problems/next-greater-numerically-balanced-number) | [[数学](../math/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 2044 | [统计按位或能得到最大值的子集数目](../../problems/count-number-of-maximum-bitwise-or-subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 2014 | [重复 K 次的最长子序列](../../problems/longest-subsequence-repeated-k-times) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2002 | [两个回文子序列长度的最大乘积](../../problems/maximum-product-of-the-length-of-two-palindromic-subsequences) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1986 | [完成任务的最少工作时间段](../../problems/minimum-number-of-work-sessions-to-finish-the-tasks) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1980 | [找出不同的二进制字符串](../../problems/find-unique-binary-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1947 | [最大兼容性评分和](../../problems/maximum-compatibility-score-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1863 | [找出所有子集的异或总和再求和](../../problems/sum-of-all-subset-xor-totals) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)]  | Easy |
-| 1849 | [将字符串拆分为递减的连续值](../../problems/splitting-a-string-into-descending-consecutive-values) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1820 | [最多邀请的个数](../../problems/maximum-number-of-accepted-invitations) 🔒 | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1799 | [N 次操作后的最大分数和](../../problems/maximize-score-after-n-operations) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1774 | [最接近目标价格的甜点成本](../../problems/closest-dessert-cost) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1723 | [完成所有工作的最短时间](../../problems/find-minimum-time-to-finish-all-jobs) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1718 | [构建字典序最大的可行序列](../../problems/construct-the-lexicographically-largest-valid-sequence) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1655 | [分配重复整数](../../problems/distribute-repeating-integers) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1601 | [最多可达成的换楼请求数目](../../problems/maximum-number-of-achievable-transfer-requests) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1593 | [拆分字符串使唯一子字符串的数目最大](../../problems/split-a-string-into-the-max-number-of-unique-substrings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1467 | [两个盒子中球的颜色数相同的概率](../../problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Hard |
-| 1415 | [长度为 n 的开心字符串中字典序第 k 小的字符串](../../problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1307 | [口算难题](../../problems/verbal-arithmetic-puzzle) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1286 | [字母组合迭代器](../../problems/iterator-for-combination) | [[设计](../design/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 1258 | [近义词句子](../../problems/synonymous-sentences) 🔒 | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1255 | [得分最高的单词集合](../../problems/maximum-score-words-formed-by-letters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1240 | [铺瓷砖](../../problems/tiling-a-rectangle-with-the-fewest-squares) | [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1239 | [串联字符串的最大长度](../../problems/maximum-length-of-a-concatenated-string-with-unique-characters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1238 | [循环码排列](../../problems/circular-permutation-in-binary-representation) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1219 | [黄金矿工](../../problems/path-with-maximum-gold) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1215 | [步进数](../../problems/stepping-numbers) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1096 | [花括号展开 II](../../problems/brace-expansion-ii) | [[栈](../stack/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1088 | [易混淆数 II](../../problems/confusing-number-ii) 🔒 | [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1087 | [花括号展开](../../problems/brace-expansion) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1079 | [活字印刷](../../problems/letter-tile-possibilities) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1066 | [校园自行车分配 II](../../problems/campus-bikes-ii) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 996 | [正方形数组的数目](../../problems/number-of-squareful-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 980 | [不同路径 III](../../problems/unique-paths-iii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 967 | [连续差相同的数字](../../problems/numbers-with-same-consecutive-differences) | [[广度优先搜索](../breadth-first-search/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 842 | [将数组拆分成斐波那契序列](../../problems/split-array-into-fibonacci-sequence) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 816 | [模糊坐标](../../problems/ambiguous-coordinates) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 797 | [所有可能的路径](../../problems/all-paths-from-source-to-target) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 784 | [字母大小写全排列](../../problems/letter-case-permutation) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 698 | [划分为k个相等的子集](../../problems/partition-to-k-equal-sum-subsets) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 691 | [贴纸拼词](../../problems/stickers-to-spell-word) | [[位运算](../bit-manipulation/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 679 | [24 点游戏](../../problems/24-game) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 638 | [大礼包](../../problems/shopping-offers) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 526 | [优美的排列](../../problems/beautiful-arrangement) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 494 | [目标和](../../problems/target-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 491 | [递增子序列](../../problems/increasing-subsequences) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 489 | [扫地机器人](../../problems/robot-room-cleaner) 🔒 | [[回溯](../backtracking/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 473 | [火柴拼正方形](../../problems/matchsticks-to-square) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 465 | [最优账单平衡](../../problems/optimal-account-balancing) 🔒 | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 425 | [单词方块](../../problems/word-squares) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 411 | [最短独占单词缩写](../../problems/minimum-unique-word-abbreviation) 🔒 | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 401 | [二进制手表](../../problems/binary-watch) | [[位运算](../bit-manipulation/README.md)] [[回溯](../backtracking/README.md)]  | Easy |
-| 357 | [计算各个位数不同的数字个数](../../problems/count-numbers-with-unique-digits) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 351 | [安卓系统手势解锁](../../problems/android-unlock-patterns) 🔒 | [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 320 | [列举单词的全部缩写](../../problems/generalized-abbreviation) 🔒 | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 306 | [累加数](../../problems/additive-number) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 301 | [删除无效的括号](../../problems/remove-invalid-parentheses) | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 294 | [翻转游戏 II](../../problems/flip-game-ii) 🔒 | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 291 | [单词规律 II](../../problems/word-pattern-ii) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 282 | [给表达式添加运算符](../../problems/expression-add-operators) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 267 | [回文排列 II](../../problems/palindrome-permutation-ii) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 257 | [二叉树的所有路径](../../problems/binary-tree-paths) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 254 | [因子的组合](../../problems/factor-combinations) 🔒 | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 216 | [组合总和 III](../../problems/combination-sum-iii) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 212 | [单词搜索 II](../../problems/word-search-ii) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 140 | [单词拆分 II](../../problems/word-break-ii) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 131 | [分割回文串](../../problems/palindrome-partitioning) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 126 | [单词接龙 II](../../problems/word-ladder-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 113 | [路径总和 II](../../problems/path-sum-ii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 95 | [不同的二叉搜索树 II](../../problems/unique-binary-search-trees-ii) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 93 | [复原 IP 地址](../../problems/restore-ip-addresses) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 90 | [子集 II](../../problems/subsets-ii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 89 | [格雷编码](../../problems/gray-code) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 79 | [单词搜索](../../problems/word-search) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 78 | [子集](../../problems/subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 77 | [组合](../../problems/combinations) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 52 | [N皇后 II](../../problems/n-queens-ii) | [[回溯](../backtracking/README.md)]  | Hard |
-| 51 | [N 皇后](../../problems/n-queens) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 47 | [全排列 II](../../problems/permutations-ii) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 46 | [全排列](../../problems/permutations) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 40 | [组合总和 II](../../problems/combination-sum-ii) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 39 | [组合总和](../../problems/combination-sum) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 37 | [解数独](../../problems/sudoku-solver) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 22 | [括号生成](../../problems/generate-parentheses) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 17 | [电话号码的字母组合](../../problems/letter-combinations-of-a-phone-number) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
diff --git a/tag/biconnected-component/README.md b/tag/biconnected-component/README.md
deleted file mode 100644
index 04440ac7e..000000000
--- a/tag/biconnected-component/README.md
+++ /dev/null
@@ -1,12 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 双连通分量
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1192 | [查找集群内的「关键连接」](../../problems/critical-connections-in-a-network) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[双连通分量](../biconnected-component/README.md)]  | Hard |
diff --git a/tag/binary-indexed-tree/README.md b/tag/binary-indexed-tree/README.md
deleted file mode 100644
index efb68694d..000000000
--- a/tag/binary-indexed-tree/README.md
+++ /dev/null
@@ -1,27 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 树状数组
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2031 | [1 比 0 多的子数组个数](../../problems/count-subarrays-with-more-ones-than-zeros) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 1964 | [找出到每个位置为止最长的有效障碍赛跑路线](../../problems/find-the-longest-valid-obstacle-course-at-each-position) | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1756 | [设计最近使用（MRU）队列](../../problems/design-most-recently-used-queue) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1649 | [通过指令创建有序数组](../../problems/create-sorted-array-through-instructions) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 1505 | [最多 K 次交换相邻数位后得到的最小整数](../../problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits) | [[贪心](../greedy/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1409 | [查询带键的排列](../../problems/queries-on-a-permutation-with-key) | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1395 | [统计作战单位数](../../problems/count-number-of-teams) | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1157 | [子数组中占绝大多数的元素](../../problems/online-majority-element-in-subarray) | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 683 | [K 个关闭的灯泡](../../problems/k-empty-slots) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 673 | [最长递增子序列的个数](../../problems/number-of-longest-increasing-subsequence) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 493 | [翻转对](../../problems/reverse-pairs) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 327 | [区间和的个数](../../problems/count-of-range-sum) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 315 | [计算右侧小于当前元素的个数](../../problems/count-of-smaller-numbers-after-self) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 308 | [二维区域和检索 - 可变](../../problems/range-sum-query-2d-mutable) 🔒 | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 307 | [区域和检索 - 数组可修改](../../problems/range-sum-query-mutable) | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)]  | Medium |
-| 218 | [天际线问题](../../problems/the-skyline-problem) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
diff --git a/tag/binary-search-tree/README.md b/tag/binary-search-tree/README.md
deleted file mode 100644
index a52f03e70..000000000
--- a/tag/binary-search-tree/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 二叉搜索树
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1902 | [给定二叉搜索树的插入顺序求深度](../../problems/depth-of-bst-given-insertion-order) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1586 | [二叉搜索树迭代器 II](../../problems/binary-search-tree-iterator-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1382 | [将二叉搜索树变平衡](../../problems/balance-a-binary-search-tree) | [[贪心](../greedy/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1373 | [二叉搜索子树的最大键值和](../../problems/maximum-sum-bst-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1305 | [两棵二叉搜索树中的所有元素](../../problems/all-elements-in-two-binary-search-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1214 | [查找两棵二叉搜索树之和](../../problems/two-sum-bsts) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1038 | [把二叉搜索树转换为累加树](../../problems/binary-search-tree-to-greater-sum-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1008 | [前序遍历构造二叉搜索树](../../problems/construct-binary-search-tree-from-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 938 | [二叉搜索树的范围和](../../problems/range-sum-of-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 897 | [递增顺序搜索树](../../problems/increasing-order-search-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 783 | [二叉搜索树节点最小距离](../../problems/minimum-distance-between-bst-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 776 | [拆分二叉搜索树](../../problems/split-bst) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 703 | [数据流中的第 K 大元素](../../problems/kth-largest-element-in-a-stream) | [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 701 | [二叉搜索树中的插入操作](../../problems/insert-into-a-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 700 | [二叉搜索树中的搜索](../../problems/search-in-a-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 669 | [修剪二叉搜索树](../../problems/trim-a-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 653 | [两数之和 IV - 输入 BST](../../problems/two-sum-iv-input-is-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 538 | [把二叉搜索树转换为累加树](../../problems/convert-bst-to-greater-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 530 | [二叉搜索树的最小绝对差](../../problems/minimum-absolute-difference-in-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 510 | [二叉搜索树中的中序后继 II](../../problems/inorder-successor-in-bst-ii) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 501 | [二叉搜索树中的众数](../../problems/find-mode-in-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 450 | [删除二叉搜索树中的节点](../../problems/delete-node-in-a-bst) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 449 | [序列化和反序列化二叉搜索树](../../problems/serialize-and-deserialize-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 426 | [将二叉搜索树转化为排序的双向链表](../../problems/convert-binary-search-tree-to-sorted-doubly-linked-list) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 333 | [最大 BST 子树](../../problems/largest-bst-subtree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 285 | [二叉搜索树中的中序后继](../../problems/inorder-successor-in-bst) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 272 | [最接近的二叉搜索树值 II](../../problems/closest-binary-search-tree-value-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 270 | [最接近的二叉搜索树值](../../problems/closest-binary-search-tree-value) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 255 | [验证前序遍历序列二叉搜索树](../../problems/verify-preorder-sequence-in-binary-search-tree) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 235 | [二叉搜索树的最近公共祖先](../../problems/lowest-common-ancestor-of-a-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 230 | [二叉搜索树中第K小的元素](../../problems/kth-smallest-element-in-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 173 | [二叉搜索树迭代器](../../problems/binary-search-tree-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 109 | [有序链表转换二叉搜索树](../../problems/convert-sorted-list-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 108 | [将有序数组转换为二叉搜索树](../../problems/convert-sorted-array-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 99 | [恢复二叉搜索树](../../problems/recover-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 98 | [验证二叉搜索树](../../problems/validate-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 96 | [不同的二叉搜索树](../../problems/unique-binary-search-trees) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 95 | [不同的二叉搜索树 II](../../problems/unique-binary-search-trees-ii) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
diff --git a/tag/binary-search/README.md b/tag/binary-search/README.md
deleted file mode 100644
index 9b634cc8e..000000000
--- a/tag/binary-search/README.md
+++ /dev/null
@@ -1,179 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 二分查找
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2141 | [同时运行 N 台电脑的最长时间](../../problems/maximum-running-time-of-n-computers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2137 | [Pour Water Between Buckets to Make Water Levels Equal](../../problems/pour-water-between-buckets-to-make-water-levels-equal) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 2111 | [使数组 K 递增的最少操作次数](../../problems/minimum-operations-to-make-the-array-k-increasing) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 2106 | [摘水果](../../problems/maximum-fruits-harvested-after-at-most-k-steps) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 2089 | [找出数组排序后的目标下标](../../problems/find-target-indices-after-sorting-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2080 | [区间内查询数字的频率](../../problems/range-frequency-queries) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 2071 | [你可以安排的最多任务数目](../../problems/maximum-number-of-tasks-you-can-assign) | [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Hard |
-| 2070 | [每一个查询的最大美丽值](../../problems/most-beautiful-item-for-each-query) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2064 | [分配给商店的最多商品的最小值](../../problems/minimized-maximum-of-products-distributed-to-any-store) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 2055 | [蜡烛之间的盘子](../../problems/plates-between-candles) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2054 | [两个最好的不重叠活动](../../problems/two-best-non-overlapping-events) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2040 | [两个有序数组的第 K 小乘积](../../problems/kth-smallest-product-of-two-sorted-arrays) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 2035 | [将数组分成两个数组并最小化数组和的差](../../problems/partition-array-into-two-arrays-to-minimize-sum-difference) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2031 | [1 比 0 多的子数组个数](../../problems/count-subarrays-with-more-ones-than-zeros) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 2024 | [考试的最大困扰度](../../problems/maximize-the-confusion-of-an-exam) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2009 | [使数组连续的最少操作数](../../problems/minimum-number-of-operations-to-make-array-continuous) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 2008 | [出租车的最大盈利](../../problems/maximum-earnings-from-taxi) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1970 | [你能穿过矩阵的最后一天](../../problems/last-day-where-you-can-still-cross) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1964 | [找出到每个位置为止最长的有效障碍赛跑路线](../../problems/find-the-longest-valid-obstacle-course-at-each-position) | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1956 | [感染 K 种病毒所需的最短时间](../../problems/minimum-time-for-k-virus-variants-to-spread) 🔒 | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1954 | [收集足够苹果的最小花园周长](../../problems/minimum-garden-perimeter-to-collect-enough-apples) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1932 | [合并多棵二叉搜索树](../../problems/merge-bsts-to-create-single-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1923 | [最长公共子路径](../../problems/longest-common-subpath) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1918 | [第 K 小的子数组和·](../../problems/kth-smallest-subarray-sum) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1901 | [找出顶峰元素 II](../../problems/find-a-peak-element-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1898 | [可移除字符的最大数目](../../problems/maximum-number-of-removable-characters) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1894 | [找到需要补充粉笔的学生编号](../../problems/find-the-student-that-will-replace-the-chalk) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1891 | [割绳子](../../problems/cutting-ribbons) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1889 | [装包裹的最小浪费空间](../../problems/minimum-space-wasted-from-packaging) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1885 | [统计数对](../../problems/count-pairs-in-two-arrays) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1870 | [准时到达的列车最小时速](../../problems/minimum-speed-to-arrive-on-time) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1862 | [向下取整数对和](../../problems/sum-of-floored-pairs) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1855 | [下标对中的最大距离](../../problems/maximum-distance-between-a-pair-of-values) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1851 | [包含每个查询的最小区间](../../problems/minimum-interval-to-include-each-query) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1847 | [最近的房间](../../problems/closest-room) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1838 | [最高频元素的频数](../../problems/frequency-of-the-most-frequent-element) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1818 | [绝对差值和](../../problems/minimum-absolute-sum-difference) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1802 | [有界数组中指定下标处的最大值](../../problems/maximum-value-at-a-given-index-in-a-bounded-array) | [[贪心](../greedy/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1793 | [好子数组的最大分数](../../problems/maximum-score-of-a-good-subarray) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1782 | [统计点对的数目](../../problems/count-pairs-of-nodes) | [[图](../graph/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1760 | [袋子里最少数目的球](../../problems/minimum-limit-of-balls-in-a-bag) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1751 | [最多可以参加的会议数目 II](../../problems/maximum-number-of-events-that-can-be-attended-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1739 | [放置盒子](../../problems/building-boxes) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1713 | [得到子序列的最少操作次数](../../problems/minimum-operations-to-make-a-subsequence) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1712 | [将数组分成三个子数组的方案数](../../problems/ways-to-split-array-into-three-subarrays) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1671 | [得到山形数组的最少删除次数](../../problems/minimum-number-of-removals-to-make-mountain-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1658 | [将 x 减到 0 的最小操作数](../../problems/minimum-operations-to-reduce-x-to-zero) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1649 | [通过指令创建有序数组](../../problems/create-sorted-array-through-instructions) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 1648 | [销售价值减少的颜色球](../../problems/sell-diminishing-valued-colored-balls) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1631 | [最小体力消耗路径](../../problems/path-with-minimum-effort) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1618 | [找出适应屏幕的最大字号](../../problems/maximum-font-to-fit-a-sentence-in-a-screen) 🔒 | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1608 | [特殊数组的特征值](../../problems/special-array-with-x-elements-greater-than-or-equal-x) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1574 | [删除最短的子数组使剩余数组有序](../../problems/shortest-subarray-to-be-removed-to-make-array-sorted) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1562 | [查找大小为 M 的最新分组](../../problems/find-latest-group-of-size-m) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1552 | [两球之间的磁力](../../problems/magnetic-force-between-two-balls) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1539 | [第 k 个缺失的正整数](../../problems/kth-missing-positive-number) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 1533 | [找到最大整数的索引](../../problems/find-the-index-of-the-large-integer) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1521 | [找到最接近目标值的函数值](../../problems/find-a-value-of-a-mysterious-function-closest-to-target) | [[位运算](../bit-manipulation/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1508 | [子数组和排序后的区间和](../../problems/range-sum-of-sorted-subarray-sums) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1498 | [满足条件的子序列数目](../../problems/number-of-subsequences-that-satisfy-the-given-sum-condition) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1488 | [避免洪水泛滥](../../problems/avoid-flood-in-the-city) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1483 | [树节点的第 K 个祖先](../../problems/kth-ancestor-of-a-tree-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1482 | [制作 m 束花所需的最少天数](../../problems/minimum-number-of-days-to-make-m-bouquets) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1477 | [找两个和为目标值且不重叠的子数组](../../problems/find-two-non-overlapping-sub-arrays-each-with-target-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1439 | [有序矩阵中的第 k 个最小数组和](../../problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1428 | [至少有一个 1 的最左端列](../../problems/leftmost-column-with-at-least-a-one) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1385 | [两个数组间的距离值](../../problems/find-the-distance-value-between-two-arrays) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1351 | [统计有序矩阵中的负数](../../problems/count-negative-numbers-in-a-sorted-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1348 | [推文计数](../../problems/tweet-counts-per-frequency) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1346 | [检查整数及其两倍数是否存在](../../problems/check-if-n-and-its-double-exist) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1337 | [矩阵中战斗力最弱的 K 行](../../problems/the-k-weakest-rows-in-a-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 1300 | [转变数组后最接近目标值的数组和](../../problems/sum-of-mutated-array-closest-to-target) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1292 | [元素和小于等于阈值的正方形的最大边长](../../problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1283 | [使结果不超过阈值的最小除数](../../problems/find-the-smallest-divisor-given-a-threshold) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1237 | [找出给定方程的正整数解](../../problems/find-positive-integer-solution-for-a-given-equation) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1235 | [规划兼职工作](../../problems/maximum-profit-in-job-scheduling) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1231 | [分享巧克力](../../problems/divide-chocolate) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1214 | [查找两棵二叉搜索树之和](../../problems/two-sum-bsts) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1213 | [三个有序数组的交集](../../problems/intersection-of-three-sorted-arrays) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1208 | [尽可能使字符串相等](../../problems/get-equal-substrings-within-budget) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1201 | [丑数 III](../../problems/ugly-number-iii) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1198 | [找出所有行中最小公共元素](../../problems/find-smallest-common-element-in-all-rows) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1187 | [使数组严格递增](../../problems/make-array-strictly-increasing) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1182 | [与目标颜色间的最短距离](../../problems/shortest-distance-to-target-color) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1170 | [比较字符串最小字母出现频次](../../problems/compare-strings-by-frequency-of-the-smallest-character) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1157 | [子数组中占绝大多数的元素](../../problems/online-majority-element-in-subarray) | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1150 | [检查一个数是否在数组中占绝大多数](../../problems/check-if-a-number-is-majority-element-in-a-sorted-array) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 1146 | [快照数组](../../problems/snapshot-array) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1099 | [小于 K 的两数之和](../../problems/two-sum-less-than-k) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1095 | [山脉数组中查找目标值](../../problems/find-in-mountain-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 1064 | [不动点](../../problems/fixed-point) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 1062 | [最长重复子串](../../problems/longest-repeating-substring) 🔒 | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1060 | [有序数组中的缺失元素](../../problems/missing-element-in-sorted-array) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1044 | [最长重复子串](../../problems/longest-duplicate-substring) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1027 | [最长等差数列](../../problems/longest-arithmetic-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1011 | [在 D 天内送达包裹的能力](../../problems/capacity-to-ship-packages-within-d-days) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1004 | [最大连续1的个数 III](../../problems/max-consecutive-ones-iii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 981 | [基于时间的键值存储](../../problems/time-based-key-value-store) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 911 | [在线选举](../../problems/online-election) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 902 | [最大为 N 的数字组合](../../problems/numbers-at-most-n-given-digit-set) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 888 | [公平的糖果交换](../../problems/fair-candy-swap) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 887 | [鸡蛋掉落](../../problems/super-egg-drop) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 878 | [第 N 个神奇数字](../../problems/nth-magical-number) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 875 | [爱吃香蕉的珂珂](../../problems/koko-eating-bananas) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 862 | [和至少为 K 的最短子数组](../../problems/shortest-subarray-with-sum-at-least-k) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 852 | [山脉数组的峰顶索引](../../problems/peak-index-in-a-mountain-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 826 | [安排工作以达到最大收益](../../problems/most-profit-assigning-work) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 825 | [适龄的朋友](../../problems/friends-of-appropriate-ages) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 793 | [阶乘函数后 K 个零](../../problems/preimage-size-of-factorial-zeroes-function) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 786 | [第 K 个最小的素数分数](../../problems/k-th-smallest-prime-fraction) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 778 | [水位上升的泳池中游泳](../../problems/swim-in-rising-water) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 774 | [最小化去加油站的最大距离](../../problems/minimize-max-distance-to-gas-station) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 754 | [到达终点数字](../../problems/reach-a-number) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 744 | [寻找比目标字母大的最小字母](../../problems/find-smallest-letter-greater-than-target) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 719 | [找出第 k 小的距离对](../../problems/find-k-th-smallest-pair-distance) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 718 | [最长重复子数组](../../problems/maximum-length-of-repeated-subarray) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 710 | [黑名单中的随机数](../../problems/random-pick-with-blacklist) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 704 | [二分查找](../../problems/binary-search) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 702 | [搜索长度未知的有序数组](../../problems/search-in-a-sorted-array-of-unknown-size) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 668 | [乘法表中第k小的数](../../problems/kth-smallest-number-in-multiplication-table) | [[二分查找](../binary-search/README.md)]  | Hard |
-| 658 | [找到 K 个最接近的元素](../../problems/find-k-closest-elements) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 644 | [子数组最大平均数 II](../../problems/maximum-average-subarray-ii) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 633 | [平方数之和](../../problems/sum-of-square-numbers) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 611 | [有效三角形的个数](../../problems/valid-triangle-number) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 540 | [有序数组中的单一元素](../../problems/single-element-in-a-sorted-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 532 | [数组中的 k-diff 数对](../../problems/k-diff-pairs-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 528 | [按权重随机选择](../../problems/random-pick-with-weight) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 497 | [非重叠矩形中的随机点](../../problems/random-point-in-non-overlapping-rectangles) | [[水塘抽样](../reservoir-sampling/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 493 | [翻转对](../../problems/reverse-pairs) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 483 | [最小好进制](../../problems/smallest-good-base) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 475 | [供暖器](../../problems/heaters) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 456 | [132 模式](../../problems/132-pattern) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 441 | [排列硬币](../../problems/arranging-coins) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 436 | [寻找右区间](../../problems/find-right-interval) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 410 | [分割数组的最大值](../../problems/split-array-largest-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 400 | [第 N 位数字](../../problems/nth-digit) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 378 | [有序矩阵中第 K 小的元素](../../problems/kth-smallest-element-in-a-sorted-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 374 | [猜数字大小](../../problems/guess-number-higher-or-lower) | [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Easy |
-| 367 | [有效的完全平方数](../../problems/valid-perfect-square) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 363 | [矩形区域不超过 K 的最大数值和](../../problems/max-sum-of-rectangle-no-larger-than-k) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 362 | [敲击计数器](../../problems/design-hit-counter) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 354 | [俄罗斯套娃信封问题](../../problems/russian-doll-envelopes) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 352 | [将数据流变为多个不相交区间](../../problems/data-stream-as-disjoint-intervals) | [[设计](../design/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 350 | [两个数组的交集 II](../../problems/intersection-of-two-arrays-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 349 | [两个数组的交集](../../problems/intersection-of-two-arrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 327 | [区间和的个数](../../problems/count-of-range-sum) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 315 | [计算右侧小于当前元素的个数](../../problems/count-of-smaller-numbers-after-self) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 302 | [包含全部黑色像素的最小矩形](../../problems/smallest-rectangle-enclosing-black-pixels) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 300 | [最长递增子序列](../../problems/longest-increasing-subsequence) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 287 | [寻找重复数](../../problems/find-the-duplicate-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 278 | [第一个错误的版本](../../problems/first-bad-version) | [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Easy |
-| 275 | [H 指数 II](../../problems/h-index-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 270 | [最接近的二叉搜索树值](../../problems/closest-binary-search-tree-value) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 259 | [较小的三数之和](../../problems/3sum-smaller) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 240 | [搜索二维矩阵 II](../../problems/search-a-2d-matrix-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 222 | [完全二叉树的节点个数](../../problems/count-complete-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 209 | [长度最小的子数组](../../problems/minimum-size-subarray-sum) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 167 | [两数之和 II - 输入有序数组](../../problems/two-sum-ii-input-array-is-sorted) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 162 | [寻找峰值](../../problems/find-peak-element) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 154 | [寻找旋转排序数组中的最小值 II](../../problems/find-minimum-in-rotated-sorted-array-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 153 | [寻找旋转排序数组中的最小值](../../problems/find-minimum-in-rotated-sorted-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 81 | [搜索旋转排序数组 II](../../problems/search-in-rotated-sorted-array-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 74 | [搜索二维矩阵](../../problems/search-a-2d-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 69 | [x 的平方根 ](../../problems/sqrtx) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 35 | [搜索插入位置](../../problems/search-insert-position) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 34 | [在排序数组中查找元素的第一个和最后一个位置](../../problems/find-first-and-last-position-of-element-in-sorted-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 33 | [搜索旋转排序数组](../../problems/search-in-rotated-sorted-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 4 | [寻找两个正序数组的中位数](../../problems/median-of-two-sorted-arrays) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)]  | Hard |
diff --git a/tag/binary-tree/README.md b/tag/binary-tree/README.md
deleted file mode 100644
index 3fa30ffc7..000000000
--- a/tag/binary-tree/README.md
+++ /dev/null
@@ -1,164 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 二叉树
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2096 | [从二叉树一个节点到另一个节点每一步的方向](../../problems/step-by-step-directions-from-a-binary-tree-node-to-another) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 2049 | [统计最高分的节点数目](../../problems/count-nodes-with-the-highest-score) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1932 | [合并多棵二叉搜索树](../../problems/merge-bsts-to-create-single-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1902 | [给定二叉搜索树的插入顺序求深度](../../problems/depth-of-bst-given-insertion-order) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1740 | [找到二叉树中的距离](../../problems/find-distance-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1676 | [二叉树的最近公共祖先 IV](../../problems/lowest-common-ancestor-of-a-binary-tree-iv) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1666 | [改变二叉树的根节点](../../problems/change-the-root-of-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1660 | [纠正二叉树](../../problems/correct-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1650 | [二叉树的最近公共祖先 III](../../problems/lowest-common-ancestor-of-a-binary-tree-iii) 🔒 | [[树](../tree/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1644 | [二叉树的最近公共祖先 II](../../problems/lowest-common-ancestor-of-a-binary-tree-ii) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1628 | [设计带解析函数的表达式树](../../problems/design-an-expression-tree-with-evaluate-function) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[数学](../math/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1612 | [检查两棵二叉表达式树是否等价](../../problems/check-if-two-expression-trees-are-equivalent) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1609 | [奇偶树](../../problems/even-odd-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1602 | [找到二叉树中最近的右侧节点](../../problems/find-nearest-right-node-in-binary-tree) 🔒 | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1597 | [根据中缀表达式构造二叉表达式树](../../problems/build-binary-expression-tree-from-infix-expression) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1586 | [二叉搜索树迭代器 II](../../problems/binary-search-tree-iterator-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1530 | [好叶子节点对的数量](../../problems/number-of-good-leaf-nodes-pairs) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1485 | [克隆含随机指针的二叉树](../../problems/clone-binary-tree-with-random-pointer) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1469 | [寻找所有的独生节点](../../problems/find-all-the-lonely-nodes) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 1457 | [二叉树中的伪回文路径](../../problems/pseudo-palindromic-paths-in-a-binary-tree) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1448 | [统计二叉树中好节点的数目](../../problems/count-good-nodes-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1430 | [判断给定的序列是否是二叉树从根到叶的路径](../../problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1382 | [将二叉搜索树变平衡](../../problems/balance-a-binary-search-tree) | [[贪心](../greedy/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1379 | [找出克隆二叉树中的相同节点](../../problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1373 | [二叉搜索子树的最大键值和](../../problems/maximum-sum-bst-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1372 | [二叉树中的最长交错路径](../../problems/longest-zigzag-path-in-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1367 | [二叉树中的列表](../../problems/linked-list-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1361 | [验证二叉树](../../problems/validate-binary-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1339 | [分裂二叉树的最大乘积](../../problems/maximum-product-of-splitted-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1325 | [删除给定值的叶子节点](../../problems/delete-leaves-with-a-given-value) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1315 | [祖父节点值为偶数的节点和](../../problems/sum-of-nodes-with-even-valued-grandparent) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1305 | [两棵二叉搜索树中的所有元素](../../problems/all-elements-in-two-binary-search-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1302 | [层数最深叶子节点的和](../../problems/deepest-leaves-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1261 | [在受污染的二叉树中查找元素](../../problems/find-elements-in-a-contaminated-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1214 | [查找两棵二叉搜索树之和](../../problems/two-sum-bsts) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1161 | [最大层内元素和](../../problems/maximum-level-sum-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1145 | [二叉树着色游戏](../../problems/binary-tree-coloring-game) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1123 | [最深叶节点的最近公共祖先](../../problems/lowest-common-ancestor-of-deepest-leaves) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1120 | [子树的最大平均值](../../problems/maximum-average-subtree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1110 | [删点成林](../../problems/delete-nodes-and-return-forest) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1104 | [二叉树寻路](../../problems/path-in-zigzag-labelled-binary-tree) | [[树](../tree/README.md)] [[数学](../math/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1080 | [根到叶路径上的不足节点](../../problems/insufficient-nodes-in-root-to-leaf-paths) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1038 | [把二叉搜索树转换为累加树](../../problems/binary-search-tree-to-greater-sum-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1028 | [从先序遍历还原二叉树](../../problems/recover-a-tree-from-preorder-traversal) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1026 | [节点与其祖先之间的最大差值](../../problems/maximum-difference-between-node-and-ancestor) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1022 | [从根到叶的二进制数之和](../../problems/sum-of-root-to-leaf-binary-numbers) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 1008 | [前序遍历构造二叉搜索树](../../problems/construct-binary-search-tree-from-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 998 | [最大二叉树 II](../../problems/maximum-binary-tree-ii) | [[树](../tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 993 | [二叉树的堂兄弟节点](../../problems/cousins-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 988 | [从叶结点开始的最小字符串](../../problems/smallest-string-starting-from-leaf) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 987 | [二叉树的垂序遍历](../../problems/vertical-order-traversal-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 979 | [在二叉树中分配硬币](../../problems/distribute-coins-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 971 | [翻转二叉树以匹配先序遍历](../../problems/flip-binary-tree-to-match-preorder-traversal) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 968 | [监控二叉树](../../problems/binary-tree-cameras) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 965 | [单值二叉树](../../problems/univalued-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 958 | [二叉树的完全性检验](../../problems/check-completeness-of-a-binary-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 951 | [翻转等价二叉树](../../problems/flip-equivalent-binary-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 938 | [二叉搜索树的范围和](../../problems/range-sum-of-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 919 | [完全二叉树插入器](../../problems/complete-binary-tree-inserter) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 897 | [递增顺序搜索树](../../problems/increasing-order-search-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 894 | [所有可能的满二叉树](../../problems/all-possible-full-binary-trees) | [[树](../tree/README.md)] [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 889 | [根据前序和后序遍历构造二叉树](../../problems/construct-binary-tree-from-preorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 872 | [叶子相似的树](../../problems/leaf-similar-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 865 | [具有所有最深节点的最小子树](../../problems/smallest-subtree-with-all-the-deepest-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 863 | [二叉树中所有距离为 K 的结点](../../problems/all-nodes-distance-k-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 814 | [二叉树剪枝](../../problems/binary-tree-pruning) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 783 | [二叉搜索树节点最小距离](../../problems/minimum-distance-between-bst-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 776 | [拆分二叉搜索树](../../problems/split-bst) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 742 | [二叉树最近的叶节点](../../problems/closest-leaf-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 703 | [数据流中的第 K 大元素](../../problems/kth-largest-element-in-a-stream) | [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 701 | [二叉搜索树中的插入操作](../../problems/insert-into-a-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 700 | [二叉搜索树中的搜索](../../problems/search-in-a-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 687 | [最长同值路径](../../problems/longest-univalue-path) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 671 | [二叉树中第二小的节点](../../problems/second-minimum-node-in-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 669 | [修剪二叉搜索树](../../problems/trim-a-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 666 | [路径总和 IV](../../problems/path-sum-iv) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 663 | [均匀树划分](../../problems/equal-tree-partition) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 662 | [二叉树最大宽度](../../problems/maximum-width-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 655 | [输出二叉树](../../problems/print-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 654 | [最大二叉树](../../problems/maximum-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 653 | [两数之和 IV - 输入 BST](../../problems/two-sum-iv-input-is-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 652 | [寻找重复的子树](../../problems/find-duplicate-subtrees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 637 | [二叉树的层平均值](../../problems/average-of-levels-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 623 | [在二叉树中增加一行](../../problems/add-one-row-to-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 617 | [合并二叉树](../../problems/merge-two-binary-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 606 | [根据二叉树创建字符串](../../problems/construct-string-from-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 572 | [另一棵树的子树](../../problems/subtree-of-another-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 563 | [二叉树的坡度](../../problems/binary-tree-tilt) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 549 | [二叉树中最长的连续序列](../../problems/binary-tree-longest-consecutive-sequence-ii) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 545 | [二叉树的边界](../../problems/boundary-of-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 543 | [二叉树的直径](../../problems/diameter-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 538 | [把二叉搜索树转换为累加树](../../problems/convert-bst-to-greater-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 536 | [从字符串生成二叉树](../../problems/construct-binary-tree-from-string) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 530 | [二叉搜索树的最小绝对差](../../problems/minimum-absolute-difference-in-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 515 | [在每个树行中找最大值](../../problems/find-largest-value-in-each-tree-row) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 513 | [找树左下角的值](../../problems/find-bottom-left-tree-value) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 510 | [二叉搜索树中的中序后继 II](../../problems/inorder-successor-in-bst-ii) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 508 | [出现次数最多的子树元素和](../../problems/most-frequent-subtree-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 501 | [二叉搜索树中的众数](../../problems/find-mode-in-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 450 | [删除二叉搜索树中的节点](../../problems/delete-node-in-a-bst) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 449 | [序列化和反序列化二叉搜索树](../../problems/serialize-and-deserialize-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 437 | [路径总和 III](../../problems/path-sum-iii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 431 | [将 N 叉树编码为二叉树](../../problems/encode-n-ary-tree-to-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 426 | [将二叉搜索树转化为排序的双向链表](../../problems/convert-binary-search-tree-to-sorted-doubly-linked-list) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 404 | [左叶子之和](../../problems/sum-of-left-leaves) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 366 | [寻找二叉树的叶子节点](../../problems/find-leaves-of-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 337 | [打家劫舍 III](../../problems/house-robber-iii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 333 | [最大 BST 子树](../../problems/largest-bst-subtree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 331 | [验证二叉树的前序序列化](../../problems/verify-preorder-serialization-of-a-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 314 | [二叉树的垂直遍历](../../problems/binary-tree-vertical-order-traversal) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 298 | [二叉树最长连续序列](../../problems/binary-tree-longest-consecutive-sequence) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 297 | [二叉树的序列化与反序列化](../../problems/serialize-and-deserialize-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 285 | [二叉搜索树中的中序后继](../../problems/inorder-successor-in-bst) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 272 | [最接近的二叉搜索树值 II](../../problems/closest-binary-search-tree-value-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 270 | [最接近的二叉搜索树值](../../problems/closest-binary-search-tree-value) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 257 | [二叉树的所有路径](../../problems/binary-tree-paths) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 255 | [验证前序遍历序列二叉搜索树](../../problems/verify-preorder-sequence-in-binary-search-tree) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 250 | [统计同值子树](../../problems/count-univalue-subtrees) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 236 | [二叉树的最近公共祖先](../../problems/lowest-common-ancestor-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 235 | [二叉搜索树的最近公共祖先](../../problems/lowest-common-ancestor-of-a-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 230 | [二叉搜索树中第K小的元素](../../problems/kth-smallest-element-in-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 226 | [翻转二叉树](../../problems/invert-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 222 | [完全二叉树的节点个数](../../problems/count-complete-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 199 | [二叉树的右视图](../../problems/binary-tree-right-side-view) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 173 | [二叉搜索树迭代器](../../problems/binary-search-tree-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 156 | [上下翻转二叉树](../../problems/binary-tree-upside-down) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 145 | [二叉树的后序遍历](../../problems/binary-tree-postorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 144 | [二叉树的前序遍历](../../problems/binary-tree-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 129 | [求根节点到叶节点数字之和](../../problems/sum-root-to-leaf-numbers) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 124 | [二叉树中的最大路径和](../../problems/binary-tree-maximum-path-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 117 | [填充每个节点的下一个右侧节点指针 II](../../problems/populating-next-right-pointers-in-each-node-ii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 116 | [填充每个节点的下一个右侧节点指针](../../problems/populating-next-right-pointers-in-each-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 114 | [二叉树展开为链表](../../problems/flatten-binary-tree-to-linked-list) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 113 | [路径总和 II](../../problems/path-sum-ii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 112 | [路径总和](../../problems/path-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 111 | [二叉树的最小深度](../../problems/minimum-depth-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 110 | [平衡二叉树](../../problems/balanced-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 109 | [有序链表转换二叉搜索树](../../problems/convert-sorted-list-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 108 | [将有序数组转换为二叉搜索树](../../problems/convert-sorted-array-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 107 | [二叉树的层序遍历 II](../../problems/binary-tree-level-order-traversal-ii) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 106 | [从中序与后序遍历序列构造二叉树](../../problems/construct-binary-tree-from-inorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 105 | [从前序与中序遍历序列构造二叉树](../../problems/construct-binary-tree-from-preorder-and-inorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 104 | [二叉树的最大深度](../../problems/maximum-depth-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 103 | [二叉树的锯齿形层序遍历](../../problems/binary-tree-zigzag-level-order-traversal) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 102 | [二叉树的层序遍历](../../problems/binary-tree-level-order-traversal) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 101 | [对称二叉树](../../problems/symmetric-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 100 | [相同的树](../../problems/same-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 99 | [恢复二叉搜索树](../../problems/recover-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 98 | [验证二叉搜索树](../../problems/validate-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 96 | [不同的二叉搜索树](../../problems/unique-binary-search-trees) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 95 | [不同的二叉搜索树 II](../../problems/unique-binary-search-trees-ii) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 94 | [二叉树的中序遍历](../../problems/binary-tree-inorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
diff --git a/tag/bit-manipulation/README.md b/tag/bit-manipulation/README.md
deleted file mode 100644
index aef205ab6..000000000
--- a/tag/bit-manipulation/README.md
+++ /dev/null
@@ -1,137 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 位运算
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2172 | [数组的最大与和](../../problems/maximum-and-sum-of-array) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 2157 | [字符串分组](../../problems/groups-of-strings) | [[位运算](../bit-manipulation/README.md)] [[并查集](../union-find/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 2152 | [Minimum Number of Lines to Cover Points](../../problems/minimum-number-of-lines-to-cover-points) 🔒 | [[位运算](../bit-manipulation/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 2151 | [基于陈述统计最多好人数](../../problems/maximum-good-people-based-on-statements) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2135 | [统计追加字母可以获得的单词数](../../problems/count-words-obtained-after-adding-a-letter) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2128 | [Remove All Ones With Row and Column Flips](../../problems/remove-all-ones-with-row-and-column-flips) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2044 | [统计按位或能得到最大值的子集数目](../../problems/count-number-of-maximum-bitwise-or-subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 2035 | [将数组分成两个数组并最小化数组和的差](../../problems/partition-array-into-two-arrays-to-minimize-sum-difference) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2002 | [两个回文子序列长度的最大乘积](../../problems/maximum-product-of-the-length-of-two-palindromic-subsequences) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1994 | [好子集的数目](../../problems/the-number-of-good-subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1986 | [完成任务的最少工作时间段](../../problems/minimum-number-of-work-sessions-to-finish-the-tasks) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1947 | [最大兼容性评分和](../../problems/maximum-compatibility-score-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1915 | [最美子字符串的数目](../../problems/number-of-wonderful-substrings) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1908 | [Nim 游戏 II](../../problems/game-of-nim) 🔒 | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1879 | [两个数组最小的异或值之和](../../problems/minimum-xor-sum-of-two-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1863 | [找出所有子集的异或总和再求和](../../problems/sum-of-all-subset-xor-totals) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)]  | Easy |
-| 1835 | [所有数对按位与结果的异或和](../../problems/find-xor-sum-of-all-pairs-bitwise-and) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1829 | [每个查询的最大异或值](../../problems/maximum-xor-for-each-query) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1815 | [得到新鲜甜甜圈的最多组数](../../problems/maximum-number-of-groups-getting-fresh-donuts) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1803 | [统计异或值在范围内的数对有多少](../../problems/count-pairs-with-xor-in-a-range) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1799 | [N 次操作后的最大分数和](../../problems/maximize-score-after-n-operations) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1787 | [使所有区间的异或结果为零](../../problems/make-the-xor-of-all-segments-equal-to-zero) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1763 | [最长的美好子字符串](../../problems/longest-nice-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1755 | [最接近目标值的子序列和](../../problems/closest-subsequence-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1738 | [找出第 K 大的异或坐标值](../../problems/find-kth-largest-xor-coordinate-value) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[快速选择](../quickselect/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1734 | [解码异或后的排列](../../problems/decode-xored-permutation) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1723 | [完成所有工作的最短时间](../../problems/find-minimum-time-to-finish-all-jobs) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1720 | [解码异或后的数组](../../problems/decode-xored-array) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Easy |
-| 1707 | [与数组中元素的最大异或值](../../problems/maximum-xor-with-an-element-from-array) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1684 | [统计一致字符串的数目](../../problems/count-the-number-of-consistent-strings) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1681 | [最小不兼容性](../../problems/minimum-incompatibility) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1680 | [连接连续二进制数字](../../problems/concatenation-of-consecutive-binary-numbers) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1659 | [最大化网格幸福感](../../problems/maximize-grid-happiness) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1655 | [分配重复整数](../../problems/distribute-repeating-integers) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1617 | [统计子树中城市之间最大距离](../../problems/count-subtrees-with-max-distance-between-cities) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1611 | [使整数变为 0 的最少操作次数](../../problems/minimum-one-bit-operations-to-make-integers-zero) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1601 | [最多可达成的换楼请求数目](../../problems/maximum-number-of-achievable-transfer-requests) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1595 | [连通两组点的最小成本](../../problems/minimum-cost-to-connect-two-groups-of-points) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1542 | [找出最长的超赞子字符串](../../problems/find-longest-awesome-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1525 | [字符串的好分割数目](../../problems/number-of-good-ways-to-split-a-string) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1521 | [找到最接近目标值的函数值](../../problems/find-a-value-of-a-mysterious-function-closest-to-target) | [[位运算](../bit-manipulation/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1506 | [找到 N 叉树的根节点](../../problems/find-root-of-n-ary-tree) 🔒 | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1494 | [并行课程 II](../../problems/parallel-courses-ii) | [[位运算](../bit-manipulation/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1486 | [数组异或操作](../../problems/xor-operation-in-an-array) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1461 | [检查一个字符串是否包含所有长度为 K 的二进制子串](../../problems/check-if-a-string-contains-all-binary-codes-of-size-k) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1457 | [二叉树中的伪回文路径](../../problems/pseudo-palindromic-paths-in-a-binary-tree) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1442 | [形成两个异或相等数组的三元组数目](../../problems/count-triplets-that-can-form-two-arrays-of-equal-xor) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1434 | [每个人戴不同帽子的方案数](../../problems/number-of-ways-to-wear-different-hats-to-each-other) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1404 | [将二进制表示减到 1 的步骤数](../../problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1386 | [安排电影院座位](../../problems/cinema-seat-allocation) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1371 | [每个元音包含偶数次的最长子字符串](../../problems/find-the-longest-substring-containing-vowels-in-even-counts) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1356 | [根据数字二进制下 1 的数目排序](../../problems/sort-integers-by-the-number-of-1-bits) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1349 | [参加考试的最大学生数](../../problems/maximum-students-taking-exam) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1342 | [将数字变成 0 的操作次数](../../problems/number-of-steps-to-reduce-a-number-to-zero) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1318 | [或运算的最小翻转次数](../../problems/minimum-flips-to-make-a-or-b-equal-to-c) | [[位运算](../bit-manipulation/README.md)]  | Medium |
-| 1310 | [子数组异或查询](../../problems/xor-queries-of-a-subarray) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1284 | [转化为全零矩阵的最少反转次数](../../problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1256 | [加密数字](../../problems/encode-number) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1255 | [得分最高的单词集合](../../problems/maximum-score-words-formed-by-letters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1239 | [串联字符串的最大长度](../../problems/maximum-length-of-a-concatenated-string-with-unique-characters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1238 | [循环码排列](../../problems/circular-permutation-in-binary-representation) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1178 | [猜字谜](../../problems/number-of-valid-words-for-each-puzzle) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1177 | [构建回文串检测](../../problems/can-make-palindrome-from-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1125 | [最小的必要团队](../../problems/smallest-sufficient-team) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1066 | [校园自行车分配 II](../../problems/campus-bikes-ii) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1009 | [十进制整数的反码](../../problems/complement-of-base-10-integer) | [[位运算](../bit-manipulation/README.md)]  | Easy |
-| 996 | [正方形数组的数目](../../problems/number-of-squareful-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 995 | [K 连续位的最小翻转次数](../../problems/minimum-number-of-k-consecutive-bit-flips) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 982 | [按位与为零的三元组](../../problems/triples-with-bitwise-and-equal-to-zero) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 980 | [不同路径 III](../../problems/unique-paths-iii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 957 | [N 天后的牢房](../../problems/prison-cells-after-n-days) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 943 | [最短超级串](../../problems/find-the-shortest-superstring) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 898 | [子数组按位或操作](../../problems/bitwise-ors-of-subarrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 868 | [二进制间距](../../problems/binary-gap) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 864 | [获取所有钥匙的最短路径](../../problems/shortest-path-to-get-all-keys) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Hard |
-| 861 | [翻转矩阵后的得分](../../problems/score-after-flipping-matrix) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 847 | [访问所有节点的最短路径](../../problems/shortest-path-visiting-all-nodes) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 810 | [黑板异或游戏](../../problems/chalkboard-xor-game) | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 805 | [数组的均值分割](../../problems/split-array-with-same-average) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 784 | [字母大小写全排列](../../problems/letter-case-permutation) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 782 | [变为棋盘](../../problems/transform-to-chessboard) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 779 | [第K个语法符号](../../problems/k-th-symbol-in-grammar) | [[位运算](../bit-manipulation/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 762 | [二进制表示中质数个计算置位](../../problems/prime-number-of-set-bits-in-binary-representation) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 756 | [金字塔转换矩阵](../../problems/pyramid-transition-matrix) | [[位运算](../bit-manipulation/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 751 | [IP 到 CIDR](../../problems/ip-to-cidr) 🔒 | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 698 | [划分为k个相等的子集](../../problems/partition-to-k-equal-sum-subsets) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 693 | [交替位二进制数](../../problems/binary-number-with-alternating-bits) | [[位运算](../bit-manipulation/README.md)]  | Easy |
-| 691 | [贴纸拼词](../../problems/stickers-to-spell-word) | [[位运算](../bit-manipulation/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 672 | [灯泡开关 Ⅱ](../../problems/bulb-switcher-ii) | [[位运算](../bit-manipulation/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Medium |
-| 645 | [错误的集合](../../problems/set-mismatch) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 638 | [大礼包](../../problems/shopping-offers) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 526 | [优美的排列](../../problems/beautiful-arrangement) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 491 | [递增子序列](../../problems/increasing-subsequences) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 477 | [汉明距离总和](../../problems/total-hamming-distance) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 476 | [数字的补数](../../problems/number-complement) | [[位运算](../bit-manipulation/README.md)]  | Easy |
-| 473 | [火柴拼正方形](../../problems/matchsticks-to-square) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 464 | [我能赢吗](../../problems/can-i-win) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 461 | [汉明距离](../../problems/hamming-distance) | [[位运算](../bit-manipulation/README.md)]  | Easy |
-| 421 | [数组中两个数的最大异或值](../../problems/maximum-xor-of-two-numbers-in-an-array) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 411 | [最短独占单词缩写](../../problems/minimum-unique-word-abbreviation) 🔒 | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 405 | [数字转换为十六进制数](../../problems/convert-a-number-to-hexadecimal) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 401 | [二进制手表](../../problems/binary-watch) | [[位运算](../bit-manipulation/README.md)] [[回溯](../backtracking/README.md)]  | Easy |
-| 397 | [整数替换](../../problems/integer-replacement) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 393 | [UTF-8 编码验证](../../problems/utf-8-validation) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Medium |
-| 389 | [找不同](../../problems/find-the-difference) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 371 | [两整数之和](../../problems/sum-of-two-integers) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Medium |
-| 342 | [4的幂](../../problems/power-of-four) | [[位运算](../bit-manipulation/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Easy |
-| 338 | [比特位计数](../../problems/counting-bits) | [[位运算](../bit-manipulation/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 320 | [列举单词的全部缩写](../../problems/generalized-abbreviation) 🔒 | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 318 | [最大单词长度乘积](../../problems/maximum-product-of-word-lengths) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 287 | [寻找重复数](../../problems/find-the-duplicate-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 268 | [丢失的数字](../../problems/missing-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 266 | [回文排列](../../problems/palindrome-permutation) 🔒 | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 260 | [只出现一次的数字 III](../../problems/single-number-iii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Medium |
-| 231 | [2 的幂](../../problems/power-of-two) | [[位运算](../bit-manipulation/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Easy |
-| 201 | [数字范围按位与](../../problems/bitwise-and-of-numbers-range) | [[位运算](../bit-manipulation/README.md)]  | Medium |
-| 191 | [位1的个数](../../problems/number-of-1-bits) | [[位运算](../bit-manipulation/README.md)]  | Easy |
-| 190 | [颠倒二进制位](../../problems/reverse-bits) | [[位运算](../bit-manipulation/README.md)] [[分治](../divide-and-conquer/README.md)]  | Easy |
-| 187 | [重复的DNA序列](../../problems/repeated-dna-sequences) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 137 | [只出现一次的数字 II](../../problems/single-number-ii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Medium |
-| 136 | [只出现一次的数字](../../problems/single-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)]  | Easy |
-| 90 | [子集 II](../../problems/subsets-ii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 89 | [格雷编码](../../problems/gray-code) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 78 | [子集](../../problems/subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 67 | [二进制求和](../../problems/add-binary) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 29 | [两数相除](../../problems/divide-two-integers) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Medium |
diff --git a/tag/bitmask/README.md b/tag/bitmask/README.md
deleted file mode 100644
index c13f4838e..000000000
--- a/tag/bitmask/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 状态压缩
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2172 | [数组的最大与和](../../problems/maximum-and-sum-of-array) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 2152 | [Minimum Number of Lines to Cover Points](../../problems/minimum-number-of-lines-to-cover-points) 🔒 | [[位运算](../bit-manipulation/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 2035 | [将数组分成两个数组并最小化数组和的差](../../problems/partition-array-into-two-arrays-to-minimize-sum-difference) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2002 | [两个回文子序列长度的最大乘积](../../problems/maximum-product-of-the-length-of-two-palindromic-subsequences) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1994 | [好子集的数目](../../problems/the-number-of-good-subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1986 | [完成任务的最少工作时间段](../../problems/minimum-number-of-work-sessions-to-finish-the-tasks) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1947 | [最大兼容性评分和](../../problems/maximum-compatibility-score-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1879 | [两个数组最小的异或值之和](../../problems/minimum-xor-sum-of-two-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1815 | [得到新鲜甜甜圈的最多组数](../../problems/maximum-number-of-groups-getting-fresh-donuts) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1799 | [N 次操作后的最大分数和](../../problems/maximize-score-after-n-operations) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1755 | [最接近目标值的子序列和](../../problems/closest-subsequence-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1723 | [完成所有工作的最短时间](../../problems/find-minimum-time-to-finish-all-jobs) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1681 | [最小不兼容性](../../problems/minimum-incompatibility) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1659 | [最大化网格幸福感](../../problems/maximize-grid-happiness) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1655 | [分配重复整数](../../problems/distribute-repeating-integers) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1617 | [统计子树中城市之间最大距离](../../problems/count-subtrees-with-max-distance-between-cities) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1595 | [连通两组点的最小成本](../../problems/minimum-cost-to-connect-two-groups-of-points) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1494 | [并行课程 II](../../problems/parallel-courses-ii) | [[位运算](../bit-manipulation/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1434 | [每个人戴不同帽子的方案数](../../problems/number-of-ways-to-wear-different-hats-to-each-other) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1349 | [参加考试的最大学生数](../../problems/maximum-students-taking-exam) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1255 | [得分最高的单词集合](../../problems/maximum-score-words-formed-by-letters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1125 | [最小的必要团队](../../problems/smallest-sufficient-team) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1066 | [校园自行车分配 II](../../problems/campus-bikes-ii) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 996 | [正方形数组的数目](../../problems/number-of-squareful-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 943 | [最短超级串](../../problems/find-the-shortest-superstring) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 847 | [访问所有节点的最短路径](../../problems/shortest-path-visiting-all-nodes) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 805 | [数组的均值分割](../../problems/split-array-with-same-average) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 698 | [划分为k个相等的子集](../../problems/partition-to-k-equal-sum-subsets) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 691 | [贴纸拼词](../../problems/stickers-to-spell-word) | [[位运算](../bit-manipulation/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 638 | [大礼包](../../problems/shopping-offers) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 526 | [优美的排列](../../problems/beautiful-arrangement) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 473 | [火柴拼正方形](../../problems/matchsticks-to-square) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 464 | [我能赢吗](../../problems/can-i-win) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
diff --git a/tag/brainteaser/README.md b/tag/brainteaser/README.md
deleted file mode 100644
index c19f7f1e2..000000000
--- a/tag/brainteaser/README.md
+++ /dev/null
@@ -1,19 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 脑筋急转弯
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1908 | [Nim 游戏 II](../../problems/game-of-nim) 🔒 | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1503 | [所有蚂蚁掉下来前的最后一刻](../../problems/last-moment-before-all-ants-fall-out-of-a-plank) | [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1227 | [飞机座位分配概率](../../problems/airplane-seat-assignment-probability) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 1033 | [移动石子直到连续](../../problems/moving-stones-until-consecutive) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1025 | [除数博弈](../../problems/divisor-game) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Easy |
-| 810 | [黑板异或游戏](../../problems/chalkboard-xor-game) | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 319 | [灯泡开关](../../problems/bulb-switcher) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)]  | Medium |
-| 292 | [Nim 游戏](../../problems/nim-game) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Easy |
diff --git a/tag/breadth-first-search/README.md b/tag/breadth-first-search/README.md
deleted file mode 100644
index 4e9f76243..000000000
--- a/tag/breadth-first-search/README.md
+++ /dev/null
@@ -1,204 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 广度优先搜索
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2146 | [价格范围内最高排名的 K 样物品](../../problems/k-highest-ranked-items-within-a-price-range) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2101 | [引爆最多的炸弹](../../problems/detonate-the-maximum-bombs) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 2092 | [找出知晓秘密的所有专家](../../problems/find-all-people-with-secret) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2059 | [转化数字的最小运算数](../../problems/minimum-operations-to-convert-number) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)]  | Medium |
-| 2045 | [到达目的地的第二短时间](../../problems/second-minimum-time-to-reach-destination) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)]  | Hard |
-| 2039 | [网络空闲的时刻](../../problems/the-time-when-the-network-becomes-idle) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1993 | [树上的操作](../../problems/operations-on-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1992 | [找到所有的农场组](../../problems/find-all-groups-of-farmland) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1971 | [寻找图中是否存在路径](../../problems/find-if-path-exists-in-graph) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Easy |
-| 1970 | [你能穿过矩阵的最后一天](../../problems/last-day-where-you-can-still-cross) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1926 | [迷宫中离入口最近的出口](../../problems/nearest-exit-from-entrance-in-maze) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1905 | [统计子岛屿](../../problems/count-sub-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1810 | [隐藏网格下的最小消耗路径](../../problems/minimum-path-cost-in-a-hidden-grid) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[交互](../interactive/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1778 | [未知网格中的最短路径](../../problems/shortest-path-in-a-hidden-grid) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1766 | [互质树](../../problems/tree-of-coprimes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1765 | [地图中的最高点](../../problems/map-of-highest-peak) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1740 | [找到二叉树中的距离](../../problems/find-distance-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1730 | [获取食物的最短路径](../../problems/shortest-path-to-get-food) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1728 | [猫和老鼠 II](../../problems/cat-and-mouse-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1660 | [纠正二叉树](../../problems/correct-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1654 | [到家的最少跳跃次数](../../problems/minimum-jumps-to-reach-home) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1631 | [最小体力消耗路径](../../problems/path-with-minimum-effort) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1625 | [执行操作后字典序最小的字符串](../../problems/lexicographically-smallest-string-after-applying-operations) | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1609 | [奇偶树](../../problems/even-odd-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1602 | [找到二叉树中最近的右侧节点](../../problems/find-nearest-right-node-in-binary-tree) 🔒 | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1568 | [使陆地分离的最少天数](../../problems/minimum-number-of-days-to-disconnect-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
-| 1559 | [二维网格图中探测环](../../problems/detect-cycles-in-2d-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1519 | [子树中标签相同的节点数](../../problems/number-of-nodes-in-the-sub-tree-with-the-same-label) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1490 | [克隆 N 叉树](../../problems/clone-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1485 | [克隆含随机指针的二叉树](../../problems/clone-binary-tree-with-random-pointer) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1483 | [树节点的第 K 个祖先](../../problems/kth-ancestor-of-a-tree-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1469 | [寻找所有的独生节点](../../problems/find-all-the-lonely-nodes) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 1466 | [重新规划路线](../../problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1462 | [课程表 IV](../../problems/course-schedule-iv) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 1457 | [二叉树中的伪回文路径](../../problems/pseudo-palindromic-paths-in-a-binary-tree) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1448 | [统计二叉树中好节点的数目](../../problems/count-good-nodes-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1443 | [收集树上所有苹果的最少时间](../../problems/minimum-time-to-collect-all-apples-in-a-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1430 | [判断给定的序列是否是二叉树从根到叶的路径](../../problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1391 | [检查网格中是否存在有效路径](../../problems/check-if-there-is-a-valid-path-in-a-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1379 | [找出克隆二叉树中的相同节点](../../problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1377 | [T 秒后青蛙的位置](../../problems/frog-position-after-t-seconds) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Hard |
-| 1376 | [通知所有员工所需的时间](../../problems/time-needed-to-inform-all-employees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1368 | [使网格图至少有一条有效路径的最小代价](../../problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1367 | [二叉树中的列表](../../problems/linked-list-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1361 | [验证二叉树](../../problems/validate-binary-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1345 | [跳跃游戏 IV](../../problems/jump-game-iv) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1325 | [删除给定值的叶子节点](../../problems/delete-leaves-with-a-given-value) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1319 | [连通网络的操作次数](../../problems/number-of-operations-to-make-network-connected) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1315 | [祖父节点值为偶数的节点和](../../problems/sum-of-nodes-with-even-valued-grandparent) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1311 | [获取你好友已观看的视频](../../problems/get-watched-videos-by-your-friends) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1306 | [跳跃游戏 III](../../problems/jump-game-iii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1302 | [层数最深叶子节点的和](../../problems/deepest-leaves-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1298 | [你能从盒子里获得的最大糖果数](../../problems/maximum-candies-you-can-get-from-boxes) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1293 | [网格中的最短路径](../../problems/shortest-path-in-a-grid-with-obstacles-elimination) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1284 | [转化为全零矩阵的最少反转次数](../../problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1273 | [删除树节点](../../problems/delete-tree-nodes) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1267 | [统计参与通信的服务器](../../problems/count-servers-that-communicate) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1263 | [推箱子](../../problems/minimum-moves-to-move-a-box-to-their-target-location) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1261 | [在受污染的二叉树中查找元素](../../problems/find-elements-in-a-contaminated-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1257 | [最小公共区域](../../problems/smallest-common-region) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1254 | [统计封闭岛屿的数目](../../problems/number-of-closed-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1245 | [树的直径](../../problems/tree-diameter) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1242 | [多线程网页爬虫](../../problems/web-crawler-multithreaded) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[多线程](../concurrency/README.md)]  | Medium |
-| 1236 | [网络爬虫](../../problems/web-crawler) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1215 | [步进数](../../problems/stepping-numbers) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1210 | [穿过迷宫的最少移动次数](../../problems/minimum-moves-to-reach-target-with-rotations) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1203 | [项目管理](../../problems/sort-items-by-groups-respecting-dependencies) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 1202 | [交换字符串中的元素](../../problems/smallest-string-with-swaps) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1197 | [进击的骑士](../../problems/minimum-knight-moves) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1162 | [地图分析](../../problems/as-far-from-land-as-possible) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1161 | [最大层内元素和](../../problems/maximum-level-sum-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1129 | [颜色交替的最短路径](../../problems/shortest-path-with-alternating-colors) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1123 | [最深叶节点的最近公共祖先](../../problems/lowest-common-ancestor-of-deepest-leaves) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1102 | [得分最高的路径](../../problems/path-with-maximum-minimum-value) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1096 | [花括号展开 II](../../problems/brace-expansion-ii) | [[栈](../stack/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1091 | [二进制矩阵中的最短路径](../../problems/shortest-path-in-binary-matrix) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1087 | [花括号展开](../../problems/brace-expansion) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1042 | [不邻接植花](../../problems/flower-planting-with-no-adjacent) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1036 | [逃离大迷宫](../../problems/escape-a-large-maze) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1034 | [边界着色](../../problems/coloring-a-border) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1020 | [飞地的数量](../../problems/number-of-enclaves) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 994 | [腐烂的橘子](../../problems/rotting-oranges) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 993 | [二叉树的堂兄弟节点](../../problems/cousins-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 987 | [二叉树的垂序遍历](../../problems/vertical-order-traversal-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 967 | [连续差相同的数字](../../problems/numbers-with-same-consecutive-differences) | [[广度优先搜索](../breadth-first-search/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 965 | [单值二叉树](../../problems/univalued-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 959 | [由斜杠划分区域](../../problems/regions-cut-by-slashes) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 958 | [二叉树的完全性检验](../../problems/check-completeness-of-a-binary-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 934 | [最短的桥](../../problems/shortest-bridge) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 928 | [尽量减少恶意软件的传播 II](../../problems/minimize-malware-spread-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 924 | [尽量减少恶意软件的传播](../../problems/minimize-malware-spread) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 919 | [完全二叉树插入器](../../problems/complete-binary-tree-inserter) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 913 | [猫和老鼠](../../problems/cat-and-mouse) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 909 | [蛇梯棋](../../problems/snakes-and-ladders) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 886 | [可能的二分法](../../problems/possible-bipartition) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 865 | [具有所有最深节点的最小子树](../../problems/smallest-subtree-with-all-the-deepest-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 864 | [获取所有钥匙的最短路径](../../problems/shortest-path-to-get-all-keys) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Hard |
-| 863 | [二叉树中所有距离为 K 的结点](../../problems/all-nodes-distance-k-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 854 | [相似度为 K 的字符串](../../problems/k-similar-strings) | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 847 | [访问所有节点的最短路径](../../problems/shortest-path-visiting-all-nodes) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 841 | [钥匙和房间](../../problems/keys-and-rooms) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 839 | [相似字符串组](../../problems/similar-string-groups) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 827 | [最大人工岛](../../problems/making-a-large-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 815 | [公交路线](../../problems/bus-routes) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 802 | [找到最终的安全状态](../../problems/find-eventual-safe-states) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 797 | [所有可能的路径](../../problems/all-paths-from-source-to-target) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 787 | [K 站中转内最便宜的航班](../../problems/cheapest-flights-within-k-stops) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 785 | [判断二分图](../../problems/is-graph-bipartite) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 783 | [二叉搜索树节点最小距离](../../problems/minimum-distance-between-bst-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 778 | [水位上升的泳池中游泳](../../problems/swim-in-rising-water) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 773 | [滑动谜题](../../problems/sliding-puzzle) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 765 | [情侣牵手](../../problems/couples-holding-hands) | [[贪心](../greedy/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 756 | [金字塔转换矩阵](../../problems/pyramid-transition-matrix) | [[位运算](../bit-manipulation/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 752 | [打开转盘锁](../../problems/open-the-lock) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 749 | [隔离病毒](../../problems/contain-virus) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 743 | [网络延迟时间](../../problems/network-delay-time) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 742 | [二叉树最近的叶节点](../../problems/closest-leaf-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 737 | [句子相似性 II](../../problems/sentence-similarity-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 733 | [图像渲染](../../problems/flood-fill) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 721 | [账户合并](../../problems/accounts-merge) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 711 | [不同岛屿的数量 II](../../problems/number-of-distinct-islands-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 695 | [岛屿的最大面积](../../problems/max-area-of-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 694 | [不同岛屿的数量](../../problems/number-of-distinct-islands) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Medium |
-| 690 | [员工的重要性](../../problems/employee-importance) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 685 | [冗余连接 II](../../problems/redundant-connection-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 684 | [冗余连接](../../problems/redundant-connection) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 675 | [为高尔夫比赛砍树](../../problems/cut-off-trees-for-golf-event) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 672 | [灯泡开关 Ⅱ](../../problems/bulb-switcher-ii) | [[位运算](../bit-manipulation/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Medium |
-| 662 | [二叉树最大宽度](../../problems/maximum-width-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 655 | [输出二叉树](../../problems/print-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 653 | [两数之和 IV - 输入 BST](../../problems/two-sum-iv-input-is-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 652 | [寻找重复的子树](../../problems/find-duplicate-subtrees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 637 | [二叉树的层平均值](../../problems/average-of-levels-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 623 | [在二叉树中增加一行](../../problems/add-one-row-to-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 617 | [合并二叉树](../../problems/merge-two-binary-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 582 | [杀掉进程](../../problems/kill-process) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 559 | [N 叉树的最大深度](../../problems/maximum-depth-of-n-ary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Easy |
-| 547 | [省份数量](../../problems/number-of-provinces) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 542 | [01 矩阵](../../problems/01-matrix) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 530 | [二叉搜索树的最小绝对差](../../problems/minimum-absolute-difference-in-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 529 | [扫雷游戏](../../problems/minesweeper) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 515 | [在每个树行中找最大值](../../problems/find-largest-value-in-each-tree-row) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 514 | [自由之路](../../problems/freedom-trail) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 513 | [找树左下角的值](../../problems/find-bottom-left-tree-value) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 505 | [迷宫 II](../../problems/the-maze-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 499 | [迷宫 III](../../problems/the-maze-iii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 490 | [迷宫](../../problems/the-maze) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 488 | [祖玛游戏](../../problems/zuma-game) | [[广度优先搜索](../breadth-first-search/README.md)] [[记忆化搜索](../memoization/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 463 | [岛屿的周长](../../problems/island-perimeter) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 449 | [序列化和反序列化二叉搜索树](../../problems/serialize-and-deserialize-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 433 | [最小基因变化](../../problems/minimum-genetic-mutation) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 431 | [将 N 叉树编码为二叉树](../../problems/encode-n-ary-tree-to-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 429 | [N 叉树的层序遍历](../../problems/n-ary-tree-level-order-traversal) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 428 | [序列化和反序列化 N 叉树](../../problems/serialize-and-deserialize-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 417 | [太平洋大西洋水流问题](../../problems/pacific-atlantic-water-flow) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 407 | [接雨水 II](../../problems/trapping-rain-water-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 404 | [左叶子之和](../../problems/sum-of-left-leaves) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 399 | [除法求值](../../problems/evaluate-division) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 365 | [水壶问题](../../problems/water-and-jug-problem) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Medium |
-| 364 | [加权嵌套序列和 II](../../problems/nested-list-weight-sum-ii) 🔒 | [[栈](../stack/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 339 | [嵌套列表权重和](../../problems/nested-list-weight-sum) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 329 | [矩阵中的最长递增路径](../../problems/longest-increasing-path-in-a-matrix) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 323 | [无向图中连通分量的数目](../../problems/number-of-connected-components-in-an-undirected-graph) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 322 | [零钱兑换](../../problems/coin-change) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 317 | [离建筑物最近的距离](../../problems/shortest-distance-from-all-buildings) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 314 | [二叉树的垂直遍历](../../problems/binary-tree-vertical-order-traversal) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 310 | [最小高度树](../../problems/minimum-height-trees) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 302 | [包含全部黑色像素的最小矩形](../../problems/smallest-rectangle-enclosing-black-pixels) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 301 | [删除无效的括号](../../problems/remove-invalid-parentheses) | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 297 | [二叉树的序列化与反序列化](../../problems/serialize-and-deserialize-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 286 | [墙与门](../../problems/walls-and-gates) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 279 | [完全平方数](../../problems/perfect-squares) | [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 269 | [火星词典](../../problems/alien-dictionary) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 261 | [以图判树](../../problems/graph-valid-tree) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 226 | [翻转二叉树](../../problems/invert-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 210 | [课程表 II](../../problems/course-schedule-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 207 | [课程表](../../problems/course-schedule) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 200 | [岛屿数量](../../problems/number-of-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 199 | [二叉树的右视图](../../problems/binary-tree-right-side-view) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 133 | [克隆图](../../problems/clone-graph) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 130 | [被围绕的区域](../../problems/surrounded-regions) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 127 | [单词接龙](../../problems/word-ladder) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 126 | [单词接龙 II](../../problems/word-ladder-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 117 | [填充每个节点的下一个右侧节点指针 II](../../problems/populating-next-right-pointers-in-each-node-ii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 116 | [填充每个节点的下一个右侧节点指针](../../problems/populating-next-right-pointers-in-each-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 112 | [路径总和](../../problems/path-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 111 | [二叉树的最小深度](../../problems/minimum-depth-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 107 | [二叉树的层序遍历 II](../../problems/binary-tree-level-order-traversal-ii) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 104 | [二叉树的最大深度](../../problems/maximum-depth-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 103 | [二叉树的锯齿形层序遍历](../../problems/binary-tree-zigzag-level-order-traversal) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 102 | [二叉树的层序遍历](../../problems/binary-tree-level-order-traversal) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 101 | [对称二叉树](../../problems/symmetric-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 100 | [相同的树](../../problems/same-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
diff --git a/tag/bucket-sort/README.md b/tag/bucket-sort/README.md
deleted file mode 100644
index 57c6c0ff4..000000000
--- a/tag/bucket-sort/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 桶排序
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 912 | [排序数组](../../problems/sort-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数排序](../counting-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 692 | [前K个高频单词](../../problems/top-k-frequent-words) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 451 | [根据字符出现频率排序](../../problems/sort-characters-by-frequency) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 347 | [前 K 个高频元素](../../problems/top-k-frequent-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 220 | [存在重复元素 III](../../problems/contains-duplicate-iii) | [[数组](../array/README.md)] [[桶排序](../bucket-sort/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 164 | [最大间距](../../problems/maximum-gap) | [[数组](../array/README.md)] [[桶排序](../bucket-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)]  | Hard |
diff --git a/tag/combinatorics/README.md b/tag/combinatorics/README.md
deleted file mode 100644
index c3322fa15..000000000
--- a/tag/combinatorics/README.md
+++ /dev/null
@@ -1,23 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 组合数学
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2063 | [所有子字符串中的元音](../../problems/vowels-of-all-substrings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Medium |
-| 1916 | [统计为蚁群构筑房间的不同顺序](../../problems/count-ways-to-build-rooms-in-an-ant-colony) | [[树](../tree/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1866 | [恰有 K 根木棍可以看到的排列数目](../../problems/number-of-ways-to-rearrange-sticks-with-k-sticks-visible) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1863 | [找出所有子集的异或总和再求和](../../problems/sum-of-all-subset-xor-totals) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)]  | Easy |
-| 1830 | [使字符串有序的最少操作次数](../../problems/minimum-number-of-operations-to-make-string-sorted) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1643 | [第 K 条最小指令](../../problems/kth-smallest-instructions) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1467 | [两个盒子中球的颜色数相同的概率](../../problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Hard |
-| 1359 | [有效的快递序列数目](../../problems/count-all-valid-pickup-and-delivery-options) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 920 | [播放列表的数量](../../problems/number-of-music-playlists) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 458 | [可怜的小猪](../../problems/poor-pigs) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 62 | [不同路径](../../problems/unique-paths) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Medium |
diff --git a/tag/concurrency/README.md b/tag/concurrency/README.md
deleted file mode 100644
index 2155bbd8d..000000000
--- a/tag/concurrency/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 多线程
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1279 | [红绿灯路口](../../problems/traffic-light-controlled-intersection) 🔒 | [[多线程](../concurrency/README.md)]  | Easy |
-| 1242 | [多线程网页爬虫](../../problems/web-crawler-multithreaded) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[多线程](../concurrency/README.md)]  | Medium |
-| 1226 | [哲学家进餐](../../problems/the-dining-philosophers) | [[多线程](../concurrency/README.md)]  | Medium |
-| 1195 | [交替打印字符串](../../problems/fizz-buzz-multithreaded) | [[多线程](../concurrency/README.md)]  | Medium |
-| 1188 | [设计有限阻塞队列](../../problems/design-bounded-blocking-queue) 🔒 | [[多线程](../concurrency/README.md)]  | Medium |
-| 1117 | [H2O 生成](../../problems/building-h2o) | [[多线程](../concurrency/README.md)]  | Medium |
-| 1116 | [打印零与奇偶数](../../problems/print-zero-even-odd) | [[多线程](../concurrency/README.md)]  | Medium |
-| 1115 | [交替打印 FooBar](../../problems/print-foobar-alternately) | [[多线程](../concurrency/README.md)]  | Medium |
-| 1114 | [按序打印](../../problems/print-in-order) | [[多线程](../concurrency/README.md)]  | Easy |
diff --git a/tag/counting-sort/README.md b/tag/counting-sort/README.md
deleted file mode 100644
index 80437a981..000000000
--- a/tag/counting-sort/README.md
+++ /dev/null
@@ -1,16 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 计数排序
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1122 | [数组的相对排序](../../problems/relative-sort-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1051 | [高度检查器](../../problems/height-checker) | [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 912 | [排序数组](../../problems/sort-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数排序](../counting-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 561 | [数组拆分 I](../../problems/array-partition-i) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 274 | [H 指数](../../problems/h-index) | [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Medium |
diff --git a/tag/counting/README.md b/tag/counting/README.md
deleted file mode 100644
index c1807c731..000000000
--- a/tag/counting/README.md
+++ /dev/null
@@ -1,79 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 计数
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2170 | [使数组变成交替数组的最少操作数](../../problems/minimum-operations-to-make-the-array-alternating) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2168 | [Unique Substrings With Equal Digit Frequency](../../problems/unique-substrings-with-equal-digit-frequency) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 2150 | [找出数组中的所有孤独数字](../../problems/find-all-lonely-numbers-in-the-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2131 | [连接两字母单词得到的最长回文串](../../problems/longest-palindrome-by-concatenating-two-letter-words) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2085 | [统计出现过一次的公共字符串](../../problems/count-common-words-with-one-occurrence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2083 | [求以相同字母开头和结尾的子串总数](../../problems/substrings-that-begin-and-end-with-the-same-letter) 🔒 | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2068 | [检查两个字符串是否几乎相等](../../problems/check-whether-two-strings-are-almost-equivalent) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2067 | [Number of Equal Count Substrings](../../problems/number-of-equal-count-substrings) 🔒 | [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2053 | [数组中第 K 个独一无二的字符串](../../problems/kth-distinct-string-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2029 | [石子游戏 IX](../../problems/stone-game-ix) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 2025 | [分割数组的最多方案数](../../problems/maximum-number-of-ways-to-partition-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 2014 | [重复 K 次的最长子序列](../../problems/longest-subsequence-repeated-k-times) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2013 | [检测正方形](../../problems/detect-squares) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2006 | [差的绝对值为 K 的数对数目](../../problems/count-number-of-pairs-with-absolute-difference-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2001 | [可互换矩形的组数](../../problems/number-of-pairs-of-interchangeable-rectangles) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1941 | [检查是否所有字符出现次数相同](../../problems/check-if-all-characters-have-equal-number-of-occurrences) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1940 | [排序数组之间的最长公共子序列](../../problems/longest-common-subsequence-between-sorted-arrays) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1897 | [重新分配字符使所有字符串都相等](../../problems/redistribute-characters-to-make-all-strings-equal) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1876 | [长度为三且各字符不同的子字符串](../../problems/substrings-of-size-three-with-distinct-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1857 | [有向图中最大颜色值](../../problems/largest-color-value-in-a-directed-graph) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)] [[计数](../counting/README.md)]  | Hard |
-| 1854 | [人口最多的年份](../../problems/maximum-population-year) | [[数组](../array/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1819 | [序列中不同最大公约数的数目](../../problems/number-of-different-subsequences-gcds) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1814 | [统计一个数组中好对子的数目](../../problems/count-nice-pairs-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1790 | [仅执行一次字符串交换能否使两个字符串相等](../../problems/check-if-one-string-swap-can-make-strings-equal) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1781 | [所有子字符串美丽值之和](../../problems/sum-of-beauty-of-all-substrings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1775 | [通过最少操作次数使数组的和相等](../../problems/equal-sum-arrays-with-minimum-number-of-operations) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1748 | [唯一元素的和](../../problems/sum-of-unique-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1742 | [盒子中小球的最大数量](../../problems/maximum-number-of-balls-in-a-box) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1737 | [满足三条件之一需改变的最少字符数](../../problems/change-minimum-characters-to-satisfy-one-of-three-conditions) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1704 | [判断字符串的两半是否相似](../../problems/determine-if-string-halves-are-alike) | [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1603 | [设计停车系统](../../problems/design-parking-system) | [[设计](../design/README.md)] [[计数](../counting/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1512 | [好数对的数目](../../problems/number-of-good-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1497 | [检查数组对是否可以被 k 整除](../../problems/check-if-array-pairs-are-divisible-by-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1481 | [不同整数的最少数目](../../problems/least-number-of-unique-integers-after-k-removals) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1419 | [数青蛙](../../problems/minimum-number-of-frogs-croaking) | [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1400 | [构造 K 个回文字符串](../../problems/construct-k-palindrome-strings) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1394 | [找出数组中的幸运数](../../problems/find-lucky-integer-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1370 | [上升下降字符串](../../problems/increasing-decreasing-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1366 | [通过投票对团队排名](../../problems/rank-teams-by-votes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1365 | [有多少小于当前数字的数字](../../problems/how-many-numbers-are-smaller-than-the-current-number) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1356 | [根据数字二进制下 1 的数目排序](../../problems/sort-integers-by-the-number-of-1-bits) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1267 | [统计参与通信的服务器](../../problems/count-servers-that-communicate) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1221 | [分割平衡字符串](../../problems/split-a-string-in-balanced-strings) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1213 | [三个有序数组的交集](../../problems/intersection-of-three-sorted-arrays) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1198 | [找出所有行中最小公共元素](../../problems/find-smallest-common-element-in-all-rows) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1189 | [“气球” 的最大数量](../../problems/maximum-number-of-balloons) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1128 | [等价多米诺骨牌对的数量](../../problems/number-of-equivalent-domino-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1090 | [受标签影响的最大值](../../problems/largest-values-from-labels) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1054 | [距离相等的条形码](../../problems/distant-barcodes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1010 | [总持续时间可被 60 整除的歌曲](../../problems/pairs-of-songs-with-total-durations-divisible-by-60) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 992 | [K 个不同整数的子数组](../../problems/subarrays-with-k-different-integers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 945 | [使数组唯一的最小增量](../../problems/minimum-increment-to-make-array-unique) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 923 | [三数之和的多种可能](../../problems/3sum-with-multiplicity) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 914 | [卡牌分组](../../problems/x-of-a-kind-in-a-deck-of-cards) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Easy |
-| 900 | [RLE 迭代器](../../problems/rle-iterator) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 869 | [重新排序得到 2 的幂](../../problems/reordered-power-of-2) | [[数学](../math/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 811 | [子域名访问计数](../../problems/subdomain-visit-count) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 767 | [重构字符串](../../problems/reorganize-string) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 692 | [前K个高频单词](../../problems/top-k-frequent-words) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 621 | [任务调度器](../../problems/task-scheduler) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 451 | [根据字符出现频率排序](../../problems/sort-characters-by-frequency) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 387 | [字符串中的第一个唯一字符](../../problems/first-unique-character-in-a-string) | [[队列](../queue/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 383 | [赎金信](../../problems/ransom-note) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 358 | [K 距离间隔重排字符串](../../problems/rearrange-string-k-distance-apart) 🔒 | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 347 | [前 K 个高频元素](../../problems/top-k-frequent-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 299 | [猜数字游戏](../../problems/bulls-and-cows) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 229 | [求众数 II](../../problems/majority-element-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 169 | [多数元素](../../problems/majority-element) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
diff --git a/tag/data-stream/README.md b/tag/data-stream/README.md
deleted file mode 100644
index c7bd52e2a..000000000
--- a/tag/data-stream/README.md
+++ /dev/null
@@ -1,27 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 数据流
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2102 | [序列顺序查询](../../problems/sequentially-ordinal-rank-tracker) | [[设计](../design/README.md)] [[数据流](../data-stream/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 2034 | [股票价格波动](../../problems/stock-price-fluctuation) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1670 | [设计前中后队列](../../problems/design-front-middle-back-queue) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1656 | [设计有序流](../../problems/design-an-ordered-stream) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 1500 | [设计文件分享系统](../../problems/design-a-file-sharing-system) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1472 | [设计浏览器历史记录](../../problems/design-browser-history) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 1429 | [第一个唯一数字](../../problems/first-unique-number) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1352 | [最后 K 个数的乘积](../../problems/product-of-the-last-k-numbers) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1032 | [字符流](../../problems/stream-of-characters) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[数据流](../data-stream/README.md)]  | Hard |
-| 933 | [最近的请求次数](../../problems/number-of-recent-calls) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 901 | [股票价格跨度](../../problems/online-stock-span) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数据流](../data-stream/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 703 | [数据流中的第 K 大元素](../../problems/kth-largest-element-in-a-stream) | [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 642 | [设计搜索自动补全系统](../../problems/design-search-autocomplete-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[数据流](../data-stream/README.md)]  | Hard |
-| 346 | [数据流中的移动平均值](../../problems/moving-average-from-data-stream) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 295 | [数据流的中位数](../../problems/find-median-from-data-stream) | [[设计](../design/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 170 | [两数之和 III - 数据结构设计](../../problems/two-sum-iii-data-structure-design) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
diff --git a/tag/depth-first-search/README.md b/tag/depth-first-search/README.md
deleted file mode 100644
index 025044f79..000000000
--- a/tag/depth-first-search/README.md
+++ /dev/null
@@ -1,248 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 深度优先搜索
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2127 | [参加会议的最多员工数](../../problems/maximum-employees-to-be-invited-to-a-meeting) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 2101 | [引爆最多的炸弹](../../problems/detonate-the-maximum-bombs) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 2097 | [合法重新排列数对](../../problems/valid-arrangement-of-pairs) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[欧拉回路](../eulerian-circuit/README.md)]  | Hard |
-| 2096 | [从二叉树一个节点到另一个节点每一步的方向](../../problems/step-by-step-directions-from-a-binary-tree-node-to-another) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 2092 | [找出知晓秘密的所有专家](../../problems/find-all-people-with-secret) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2049 | [统计最高分的节点数目](../../problems/count-nodes-with-the-highest-score) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 2003 | [每棵子树内缺失的最小基因值](../../problems/smallest-missing-genetic-value-in-each-subtree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1992 | [找到所有的农场组](../../problems/find-all-groups-of-farmland) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1971 | [寻找图中是否存在路径](../../problems/find-if-path-exists-in-graph) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Easy |
-| 1970 | [你能穿过矩阵的最后一天](../../problems/last-day-where-you-can-still-cross) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1932 | [合并多棵二叉搜索树](../../problems/merge-bsts-to-create-single-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1905 | [统计子岛屿](../../problems/count-sub-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1858 | [包含所有前缀的最长单词](../../problems/longest-word-with-all-prefixes) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[字典树](../trie/README.md)]  | Medium |
-| 1810 | [隐藏网格下的最小消耗路径](../../problems/minimum-path-cost-in-a-hidden-grid) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[交互](../interactive/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1778 | [未知网格中的最短路径](../../problems/shortest-path-in-a-hidden-grid) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1766 | [互质树](../../problems/tree-of-coprimes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1740 | [找到二叉树中的距离](../../problems/find-distance-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1722 | [执行交换操作后的最小汉明距离](../../problems/minimize-hamming-distance-after-swap-operations) | [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1706 | [球会落何处](../../problems/where-will-the-ball-fall) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1676 | [二叉树的最近公共祖先 IV](../../problems/lowest-common-ancestor-of-a-binary-tree-iv) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1666 | [改变二叉树的根节点](../../problems/change-the-root-of-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1660 | [纠正二叉树](../../problems/correct-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1644 | [二叉树的最近公共祖先 II](../../problems/lowest-common-ancestor-of-a-binary-tree-ii) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1631 | [最小体力消耗路径](../../problems/path-with-minimum-effort) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1612 | [检查两棵二叉表达式树是否等价](../../problems/check-if-two-expression-trees-are-equivalent) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1600 | [皇位继承顺序](../../problems/throne-inheritance) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1568 | [使陆地分离的最少天数](../../problems/minimum-number-of-days-to-disconnect-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
-| 1559 | [二维网格图中探测环](../../problems/detect-cycles-in-2d-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1530 | [好叶子节点对的数量](../../problems/number-of-good-leaf-nodes-pairs) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1522 | [N 叉树的直径](../../problems/diameter-of-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Medium |
-| 1519 | [子树中标签相同的节点数](../../problems/number-of-nodes-in-the-sub-tree-with-the-same-label) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1516 | [移动 N 叉树的子树](../../problems/move-sub-tree-of-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Hard |
-| 1506 | [找到 N 叉树的根节点](../../problems/find-root-of-n-ary-tree) 🔒 | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1490 | [克隆 N 叉树](../../problems/clone-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1485 | [克隆含随机指针的二叉树](../../problems/clone-binary-tree-with-random-pointer) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1483 | [树节点的第 K 个祖先](../../problems/kth-ancestor-of-a-tree-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1469 | [寻找所有的独生节点](../../problems/find-all-the-lonely-nodes) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 1466 | [重新规划路线](../../problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1462 | [课程表 IV](../../problems/course-schedule-iv) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 1457 | [二叉树中的伪回文路径](../../problems/pseudo-palindromic-paths-in-a-binary-tree) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1448 | [统计二叉树中好节点的数目](../../problems/count-good-nodes-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1443 | [收集树上所有苹果的最少时间](../../problems/minimum-time-to-collect-all-apples-in-a-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1430 | [判断给定的序列是否是二叉树从根到叶的路径](../../problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1391 | [检查网格中是否存在有效路径](../../problems/check-if-there-is-a-valid-path-in-a-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1382 | [将二叉搜索树变平衡](../../problems/balance-a-binary-search-tree) | [[贪心](../greedy/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1379 | [找出克隆二叉树中的相同节点](../../problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1377 | [T 秒后青蛙的位置](../../problems/frog-position-after-t-seconds) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Hard |
-| 1376 | [通知所有员工所需的时间](../../problems/time-needed-to-inform-all-employees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1373 | [二叉搜索子树的最大键值和](../../problems/maximum-sum-bst-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1372 | [二叉树中的最长交错路径](../../problems/longest-zigzag-path-in-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1367 | [二叉树中的列表](../../problems/linked-list-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1361 | [验证二叉树](../../problems/validate-binary-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1339 | [分裂二叉树的最大乘积](../../problems/maximum-product-of-splitted-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1325 | [删除给定值的叶子节点](../../problems/delete-leaves-with-a-given-value) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1319 | [连通网络的操作次数](../../problems/number-of-operations-to-make-network-connected) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1315 | [祖父节点值为偶数的节点和](../../problems/sum-of-nodes-with-even-valued-grandparent) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1306 | [跳跃游戏 III](../../problems/jump-game-iii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1305 | [两棵二叉搜索树中的所有元素](../../problems/all-elements-in-two-binary-search-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1302 | [层数最深叶子节点的和](../../problems/deepest-leaves-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1273 | [删除树节点](../../problems/delete-tree-nodes) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1267 | [统计参与通信的服务器](../../problems/count-servers-that-communicate) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1261 | [在受污染的二叉树中查找元素](../../problems/find-elements-in-a-contaminated-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1257 | [最小公共区域](../../problems/smallest-common-region) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1254 | [统计封闭岛屿的数目](../../problems/number-of-closed-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1245 | [树的直径](../../problems/tree-diameter) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1242 | [多线程网页爬虫](../../problems/web-crawler-multithreaded) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[多线程](../concurrency/README.md)]  | Medium |
-| 1236 | [网络爬虫](../../problems/web-crawler) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1214 | [查找两棵二叉搜索树之和](../../problems/two-sum-bsts) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1203 | [项目管理](../../problems/sort-items-by-groups-respecting-dependencies) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 1202 | [交换字符串中的元素](../../problems/smallest-string-with-swaps) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1192 | [查找集群内的「关键连接」](../../problems/critical-connections-in-a-network) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[双连通分量](../biconnected-component/README.md)]  | Hard |
-| 1161 | [最大层内元素和](../../problems/maximum-level-sum-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1145 | [二叉树着色游戏](../../problems/binary-tree-coloring-game) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1123 | [最深叶节点的最近公共祖先](../../problems/lowest-common-ancestor-of-deepest-leaves) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1120 | [子树的最大平均值](../../problems/maximum-average-subtree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1110 | [删点成林](../../problems/delete-nodes-and-return-forest) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1102 | [得分最高的路径](../../problems/path-with-maximum-minimum-value) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1080 | [根到叶路径上的不足节点](../../problems/insufficient-nodes-in-root-to-leaf-paths) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1059 | [从始点到终点的所有路径](../../problems/all-paths-from-source-lead-to-destination) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1042 | [不邻接植花](../../problems/flower-planting-with-no-adjacent) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1038 | [把二叉搜索树转换为累加树](../../problems/binary-search-tree-to-greater-sum-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1036 | [逃离大迷宫](../../problems/escape-a-large-maze) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1034 | [边界着色](../../problems/coloring-a-border) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1028 | [从先序遍历还原二叉树](../../problems/recover-a-tree-from-preorder-traversal) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1026 | [节点与其祖先之间的最大差值](../../problems/maximum-difference-between-node-and-ancestor) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1022 | [从根到叶的二进制数之和](../../problems/sum-of-root-to-leaf-binary-numbers) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 1020 | [飞地的数量](../../problems/number-of-enclaves) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 993 | [二叉树的堂兄弟节点](../../problems/cousins-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 988 | [从叶结点开始的最小字符串](../../problems/smallest-string-starting-from-leaf) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 987 | [二叉树的垂序遍历](../../problems/vertical-order-traversal-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 979 | [在二叉树中分配硬币](../../problems/distribute-coins-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 971 | [翻转二叉树以匹配先序遍历](../../problems/flip-binary-tree-to-match-preorder-traversal) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 968 | [监控二叉树](../../problems/binary-tree-cameras) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 965 | [单值二叉树](../../problems/univalued-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 959 | [由斜杠划分区域](../../problems/regions-cut-by-slashes) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 951 | [翻转等价二叉树](../../problems/flip-equivalent-binary-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 947 | [移除最多的同行或同列石头](../../problems/most-stones-removed-with-same-row-or-column) | [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 938 | [二叉搜索树的范围和](../../problems/range-sum-of-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 934 | [最短的桥](../../problems/shortest-bridge) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 928 | [尽量减少恶意软件的传播 II](../../problems/minimize-malware-spread-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 924 | [尽量减少恶意软件的传播](../../problems/minimize-malware-spread) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 897 | [递增顺序搜索树](../../problems/increasing-order-search-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 886 | [可能的二分法](../../problems/possible-bipartition) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 872 | [叶子相似的树](../../problems/leaf-similar-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 865 | [具有所有最深节点的最小子树](../../problems/smallest-subtree-with-all-the-deepest-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 863 | [二叉树中所有距离为 K 的结点](../../problems/all-nodes-distance-k-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 851 | [喧闹和富有](../../problems/loud-and-rich) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)]  | Medium |
-| 841 | [钥匙和房间](../../problems/keys-and-rooms) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 839 | [相似字符串组](../../problems/similar-string-groups) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 834 | [树中距离之和](../../problems/sum-of-distances-in-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 827 | [最大人工岛](../../problems/making-a-large-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 814 | [二叉树剪枝](../../problems/binary-tree-pruning) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 802 | [找到最终的安全状态](../../problems/find-eventual-safe-states) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 797 | [所有可能的路径](../../problems/all-paths-from-source-to-target) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 787 | [K 站中转内最便宜的航班](../../problems/cheapest-flights-within-k-stops) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 785 | [判断二分图](../../problems/is-graph-bipartite) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 783 | [二叉搜索树节点最小距离](../../problems/minimum-distance-between-bst-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 778 | [水位上升的泳池中游泳](../../problems/swim-in-rising-water) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 765 | [情侣牵手](../../problems/couples-holding-hands) | [[贪心](../greedy/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 756 | [金字塔转换矩阵](../../problems/pyramid-transition-matrix) | [[位运算](../bit-manipulation/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 753 | [破解保险箱](../../problems/cracking-the-safe) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[欧拉回路](../eulerian-circuit/README.md)]  | Hard |
-| 749 | [隔离病毒](../../problems/contain-virus) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 743 | [网络延迟时间](../../problems/network-delay-time) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 742 | [二叉树最近的叶节点](../../problems/closest-leaf-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 737 | [句子相似性 II](../../problems/sentence-similarity-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 733 | [图像渲染](../../problems/flood-fill) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 721 | [账户合并](../../problems/accounts-merge) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 711 | [不同岛屿的数量 II](../../problems/number-of-distinct-islands-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 695 | [岛屿的最大面积](../../problems/max-area-of-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 694 | [不同岛屿的数量](../../problems/number-of-distinct-islands) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Medium |
-| 690 | [员工的重要性](../../problems/employee-importance) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 687 | [最长同值路径](../../problems/longest-univalue-path) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 685 | [冗余连接 II](../../problems/redundant-connection-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 684 | [冗余连接](../../problems/redundant-connection) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 672 | [灯泡开关 Ⅱ](../../problems/bulb-switcher-ii) | [[位运算](../bit-manipulation/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Medium |
-| 671 | [二叉树中第二小的节点](../../problems/second-minimum-node-in-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 669 | [修剪二叉搜索树](../../problems/trim-a-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 666 | [路径总和 IV](../../problems/path-sum-iv) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 663 | [均匀树划分](../../problems/equal-tree-partition) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 662 | [二叉树最大宽度](../../problems/maximum-width-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 655 | [输出二叉树](../../problems/print-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 653 | [两数之和 IV - 输入 BST](../../problems/two-sum-iv-input-is-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 652 | [寻找重复的子树](../../problems/find-duplicate-subtrees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 637 | [二叉树的层平均值](../../problems/average-of-levels-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 623 | [在二叉树中增加一行](../../problems/add-one-row-to-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 617 | [合并二叉树](../../problems/merge-two-binary-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 606 | [根据二叉树创建字符串](../../problems/construct-string-from-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 590 | [N 叉树的后序遍历](../../problems/n-ary-tree-postorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Easy |
-| 589 | [N 叉树的前序遍历](../../problems/n-ary-tree-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Easy |
-| 582 | [杀掉进程](../../problems/kill-process) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 572 | [另一棵树的子树](../../problems/subtree-of-another-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 565 | [数组嵌套](../../problems/array-nesting) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)]  | Medium |
-| 563 | [二叉树的坡度](../../problems/binary-tree-tilt) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 559 | [N 叉树的最大深度](../../problems/maximum-depth-of-n-ary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Easy |
-| 549 | [二叉树中最长的连续序列](../../problems/binary-tree-longest-consecutive-sequence-ii) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 547 | [省份数量](../../problems/number-of-provinces) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 545 | [二叉树的边界](../../problems/boundary-of-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 543 | [二叉树的直径](../../problems/diameter-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 538 | [把二叉搜索树转换为累加树](../../problems/convert-bst-to-greater-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 536 | [从字符串生成二叉树](../../problems/construct-binary-tree-from-string) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 530 | [二叉搜索树的最小绝对差](../../problems/minimum-absolute-difference-in-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 529 | [扫雷游戏](../../problems/minesweeper) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 515 | [在每个树行中找最大值](../../problems/find-largest-value-in-each-tree-row) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 514 | [自由之路](../../problems/freedom-trail) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 513 | [找树左下角的值](../../problems/find-bottom-left-tree-value) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 508 | [出现次数最多的子树元素和](../../problems/most-frequent-subtree-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 505 | [迷宫 II](../../problems/the-maze-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 501 | [二叉搜索树中的众数](../../problems/find-mode-in-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 499 | [迷宫 III](../../problems/the-maze-iii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 490 | [迷宫](../../problems/the-maze) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 472 | [连接词](../../problems/concatenated-words) | [[深度优先搜索](../depth-first-search/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 463 | [岛屿的周长](../../problems/island-perimeter) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 449 | [序列化和反序列化二叉搜索树](../../problems/serialize-and-deserialize-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 437 | [路径总和 III](../../problems/path-sum-iii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 431 | [将 N 叉树编码为二叉树](../../problems/encode-n-ary-tree-to-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 430 | [扁平化多级双向链表](../../problems/flatten-a-multilevel-doubly-linked-list) | [[深度优先搜索](../depth-first-search/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 428 | [序列化和反序列化 N 叉树](../../problems/serialize-and-deserialize-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 426 | [将二叉搜索树转化为排序的双向链表](../../problems/convert-binary-search-tree-to-sorted-doubly-linked-list) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 419 | [甲板上的战舰](../../problems/battleships-in-a-board) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 417 | [太平洋大西洋水流问题](../../problems/pacific-atlantic-water-flow) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 404 | [左叶子之和](../../problems/sum-of-left-leaves) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 399 | [除法求值](../../problems/evaluate-division) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 388 | [文件的最长绝对路径](../../problems/longest-absolute-file-path) | [[栈](../stack/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 386 | [字典序排数](../../problems/lexicographical-numbers) | [[深度优先搜索](../depth-first-search/README.md)] [[字典树](../trie/README.md)]  | Medium |
-| 385 | [迷你语法分析器](../../problems/mini-parser) | [[栈](../stack/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 366 | [寻找二叉树的叶子节点](../../problems/find-leaves-of-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 365 | [水壶问题](../../problems/water-and-jug-problem) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Medium |
-| 364 | [加权嵌套序列和 II](../../problems/nested-list-weight-sum-ii) 🔒 | [[栈](../stack/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 341 | [扁平化嵌套列表迭代器](../../problems/flatten-nested-list-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 339 | [嵌套列表权重和](../../problems/nested-list-weight-sum) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 337 | [打家劫舍 III](../../problems/house-robber-iii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 333 | [最大 BST 子树](../../problems/largest-bst-subtree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 332 | [重新安排行程](../../problems/reconstruct-itinerary) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[欧拉回路](../eulerian-circuit/README.md)]  | Hard |
-| 329 | [矩阵中的最长递增路径](../../problems/longest-increasing-path-in-a-matrix) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 323 | [无向图中连通分量的数目](../../problems/number-of-connected-components-in-an-undirected-graph) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 314 | [二叉树的垂直遍历](../../problems/binary-tree-vertical-order-traversal) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 310 | [最小高度树](../../problems/minimum-height-trees) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 302 | [包含全部黑色像素的最小矩形](../../problems/smallest-rectangle-enclosing-black-pixels) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 298 | [二叉树最长连续序列](../../problems/binary-tree-longest-consecutive-sequence) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 297 | [二叉树的序列化与反序列化](../../problems/serialize-and-deserialize-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 285 | [二叉搜索树中的中序后继](../../problems/inorder-successor-in-bst) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 272 | [最接近的二叉搜索树值 II](../../problems/closest-binary-search-tree-value-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 270 | [最接近的二叉搜索树值](../../problems/closest-binary-search-tree-value) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 269 | [火星词典](../../problems/alien-dictionary) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 261 | [以图判树](../../problems/graph-valid-tree) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 257 | [二叉树的所有路径](../../problems/binary-tree-paths) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 250 | [统计同值子树](../../problems/count-univalue-subtrees) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 236 | [二叉树的最近公共祖先](../../problems/lowest-common-ancestor-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 235 | [二叉搜索树的最近公共祖先](../../problems/lowest-common-ancestor-of-a-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 230 | [二叉搜索树中第K小的元素](../../problems/kth-smallest-element-in-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 226 | [翻转二叉树](../../problems/invert-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 222 | [完全二叉树的节点个数](../../problems/count-complete-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 211 | [添加与搜索单词 - 数据结构设计](../../problems/design-add-and-search-words-data-structure) | [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 210 | [课程表 II](../../problems/course-schedule-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 207 | [课程表](../../problems/course-schedule) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 200 | [岛屿数量](../../problems/number-of-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 199 | [二叉树的右视图](../../problems/binary-tree-right-side-view) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 156 | [上下翻转二叉树](../../problems/binary-tree-upside-down) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 145 | [二叉树的后序遍历](../../problems/binary-tree-postorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 144 | [二叉树的前序遍历](../../problems/binary-tree-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 133 | [克隆图](../../problems/clone-graph) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 130 | [被围绕的区域](../../problems/surrounded-regions) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 129 | [求根节点到叶节点数字之和](../../problems/sum-root-to-leaf-numbers) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 124 | [二叉树中的最大路径和](../../problems/binary-tree-maximum-path-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 117 | [填充每个节点的下一个右侧节点指针 II](../../problems/populating-next-right-pointers-in-each-node-ii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 116 | [填充每个节点的下一个右侧节点指针](../../problems/populating-next-right-pointers-in-each-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 114 | [二叉树展开为链表](../../problems/flatten-binary-tree-to-linked-list) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 113 | [路径总和 II](../../problems/path-sum-ii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 112 | [路径总和](../../problems/path-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 111 | [二叉树的最小深度](../../problems/minimum-depth-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 110 | [平衡二叉树](../../problems/balanced-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 104 | [二叉树的最大深度](../../problems/maximum-depth-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 101 | [对称二叉树](../../problems/symmetric-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 100 | [相同的树](../../problems/same-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 99 | [恢复二叉搜索树](../../problems/recover-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 98 | [验证二叉搜索树](../../problems/validate-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 94 | [二叉树的中序遍历](../../problems/binary-tree-inorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
diff --git a/tag/dequeue/README.md b/tag/dequeue/README.md
deleted file mode 100644
index f86e5c7c7..000000000
--- a/tag/dequeue/README.md
+++ /dev/null
@@ -1,11 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > Dequeue
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
diff --git a/tag/design/README.md b/tag/design/README.md
deleted file mode 100644
index 2dc5e63d6..000000000
--- a/tag/design/README.md
+++ /dev/null
@@ -1,116 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 设计
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2166 | [设计位集](../../problems/design-bitset) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 2102 | [序列顺序查询](../../problems/sequentially-ordinal-rank-tracker) | [[设计](../design/README.md)] [[数据流](../data-stream/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 2080 | [区间内查询数字的频率](../../problems/range-frequency-queries) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 2069 | [模拟行走机器人 II](../../problems/walking-robot-simulation-ii) | [[设计](../design/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2043 | [简易银行系统](../../problems/simple-bank-system) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2034 | [股票价格波动](../../problems/stock-price-fluctuation) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2013 | [检测正方形](../../problems/detect-squares) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1993 | [树上的操作](../../problems/operations-on-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1912 | [设计电影租借系统](../../problems/design-movie-rental-system) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1865 | [找出和为指定值的下标对](../../problems/finding-pairs-with-a-certain-sum) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1845 | [座位预约管理系统](../../problems/seat-reservation-manager) | [[设计](../design/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1825 | [求出 MK 平均值](../../problems/finding-mk-average) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1804 | [实现 Trie （前缀树） II](../../problems/implement-trie-ii-prefix-tree) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1797 | [设计一个验证系统](../../problems/design-authentication-manager) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1756 | [设计最近使用（MRU）队列](../../problems/design-most-recently-used-queue) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1670 | [设计前中后队列](../../problems/design-front-middle-back-queue) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1656 | [设计有序流](../../problems/design-an-ordered-stream) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 1628 | [设计带解析函数的表达式树](../../problems/design-an-expression-tree-with-evaluate-function) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[数学](../math/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1622 | [奇妙序列](../../problems/fancy-sequence) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1603 | [设计停车系统](../../problems/design-parking-system) | [[设计](../design/README.md)] [[计数](../counting/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1600 | [皇位继承顺序](../../problems/throne-inheritance) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1586 | [二叉搜索树迭代器 II](../../problems/binary-search-tree-iterator-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 1570 | [两个稀疏向量的点积](../../problems/dot-product-of-two-sparse-vectors) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1500 | [设计文件分享系统](../../problems/design-a-file-sharing-system) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1483 | [树节点的第 K 个祖先](../../problems/kth-ancestor-of-a-tree-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1476 | [子矩形查询](../../problems/subrectangle-queries) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1472 | [设计浏览器历史记录](../../problems/design-browser-history) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 1429 | [第一个唯一数字](../../problems/first-unique-number) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1396 | [设计地铁系统](../../problems/design-underground-system) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1381 | [设计一个支持增量操作的栈](../../problems/design-a-stack-with-increment-operation) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1357 | [每隔 n 个顾客打折](../../problems/apply-discount-every-n-orders) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1352 | [最后 K 个数的乘积](../../problems/product-of-the-last-k-numbers) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1348 | [推文计数](../../problems/tweet-counts-per-frequency) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1286 | [字母组合迭代器](../../problems/iterator-for-combination) | [[设计](../design/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 1261 | [在受污染的二叉树中查找元素](../../problems/find-elements-in-a-contaminated-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1244 | [力扣排行榜](../../problems/design-a-leaderboard) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1206 | [设计跳表](../../problems/design-skiplist) | [[设计](../design/README.md)] [[链表](../linked-list/README.md)]  | Hard |
-| 1172 | [餐盘栈](../../problems/dinner-plate-stacks) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1166 | [设计文件系统](../../problems/design-file-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1157 | [子数组中占绝大多数的元素](../../problems/online-majority-element-in-subarray) | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1146 | [快照数组](../../problems/snapshot-array) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1032 | [字符流](../../problems/stream-of-characters) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[数据流](../data-stream/README.md)]  | Hard |
-| 981 | [基于时间的键值存储](../../problems/time-based-key-value-store) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 933 | [最近的请求次数](../../problems/number-of-recent-calls) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 919 | [完全二叉树插入器](../../problems/complete-binary-tree-inserter) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 911 | [在线选举](../../problems/online-election) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 901 | [股票价格跨度](../../problems/online-stock-span) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数据流](../data-stream/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 900 | [RLE 迭代器](../../problems/rle-iterator) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 895 | [最大频率栈](../../problems/maximum-frequency-stack) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 855 | [考场就座](../../problems/exam-room) | [[设计](../design/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 745 | [前缀和后缀搜索](../../problems/prefix-and-suffix-search) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 732 | [我的日程安排表 III](../../problems/my-calendar-iii) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 731 | [我的日程安排表 II](../../problems/my-calendar-ii) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 729 | [我的日程安排表 I](../../problems/my-calendar-i) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 716 | [最大栈](../../problems/max-stack) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)] [[有序集合](../ordered-set/README.md)]  | Easy |
-| 715 | [Range 模块](../../problems/range-module) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 707 | [设计链表](../../problems/design-linked-list) | [[设计](../design/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 706 | [设计哈希映射](../../problems/design-hashmap) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 705 | [设计哈希集合](../../problems/design-hashset) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 703 | [数据流中的第 K 大元素](../../problems/kth-largest-element-in-a-stream) | [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 677 | [键值映射](../../problems/map-sum-pairs) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 676 | [实现一个魔法字典](../../problems/implement-magic-dictionary) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 642 | [设计搜索自动补全系统](../../problems/design-search-autocomplete-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[数据流](../data-stream/README.md)]  | Hard |
-| 641 | [设计循环双端队列](../../problems/design-circular-deque) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 635 | [设计日志存储系统](../../problems/design-log-storage-system) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 631 | [设计 Excel 求和公式](../../problems/design-excel-sum-formula) 🔒 | [[图](../graph/README.md)] [[设计](../design/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 622 | [设计循环队列](../../problems/design-circular-queue) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 604 | [迭代压缩字符串](../../problems/design-compressed-string-iterator) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[迭代器](../iterator/README.md)]  | Easy |
-| 588 | [设计内存文件系统](../../problems/design-in-memory-file-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 535 | [TinyURL 的加密与解密](../../problems/encode-and-decode-tinyurl) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)]  | Medium |
-| 460 | [LFU 缓存](../../problems/lfu-cache) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Hard |
-| 449 | [序列化和反序列化二叉搜索树](../../problems/serialize-and-deserialize-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 432 | [全 O(1) 的数据结构](../../problems/all-oone-data-structure) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Hard |
-| 431 | [将 N 叉树编码为二叉树](../../problems/encode-n-ary-tree-to-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 381 | [O(1) 时间插入、删除和获取随机元素 - 允许重复](../../problems/insert-delete-getrandom-o1-duplicates-allowed) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 380 | [O(1) 时间插入、删除和获取随机元素](../../problems/insert-delete-getrandom-o1) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 379 | [电话目录管理系统](../../problems/design-phone-directory) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 362 | [敲击计数器](../../problems/design-hit-counter) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 359 | [日志速率限制器](../../problems/logger-rate-limiter) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 355 | [设计推特](../../problems/design-twitter) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 353 | [贪吃蛇](../../problems/design-snake-game) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 352 | [将数据流变为多个不相交区间](../../problems/data-stream-as-disjoint-intervals) | [[设计](../design/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 348 | [设计井字棋](../../problems/design-tic-tac-toe) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 346 | [数据流中的移动平均值](../../problems/moving-average-from-data-stream) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 341 | [扁平化嵌套列表迭代器](../../problems/flatten-nested-list-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 308 | [二维区域和检索 - 可变](../../problems/range-sum-query-2d-mutable) 🔒 | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 307 | [区域和检索 - 数组可修改](../../problems/range-sum-query-mutable) | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)]  | Medium |
-| 304 | [二维区域和检索 - 矩阵不可变](../../problems/range-sum-query-2d-immutable) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 303 | [区域和检索 - 数组不可变](../../problems/range-sum-query-immutable) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 297 | [二叉树的序列化与反序列化](../../problems/serialize-and-deserialize-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 295 | [数据流的中位数](../../problems/find-median-from-data-stream) | [[设计](../design/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 288 | [单词的唯一缩写](../../problems/unique-word-abbreviation) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 284 | [顶端迭代器](../../problems/peeking-iterator) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 281 | [锯齿迭代器](../../problems/zigzag-iterator) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 271 | [字符串的编码与解码](../../problems/encode-and-decode-strings) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 251 | [展开二维向量](../../problems/flatten-2d-vector) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 244 | [最短单词距离 II](../../problems/shortest-word-distance-ii) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 232 | [用栈实现队列](../../problems/implement-queue-using-stacks) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)]  | Easy |
-| 225 | [用队列实现栈](../../problems/implement-stack-using-queues) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)]  | Easy |
-| 211 | [添加与搜索单词 - 数据结构设计](../../problems/design-add-and-search-words-data-structure) | [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 208 | [实现 Trie (前缀树)](../../problems/implement-trie-prefix-tree) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 173 | [二叉搜索树迭代器](../../problems/binary-search-tree-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 170 | [两数之和 III - 数据结构设计](../../problems/two-sum-iii-data-structure-design) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 155 | [最小栈](../../problems/min-stack) | [[栈](../stack/README.md)] [[设计](../design/README.md)]  | Easy |
-| 146 | [LRU 缓存](../../problems/lru-cache) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
diff --git a/tag/divide-and-conquer/README.md b/tag/divide-and-conquer/README.md
deleted file mode 100644
index e8c6de06d..000000000
--- a/tag/divide-and-conquer/README.md
+++ /dev/null
@@ -1,48 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 分治
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2031 | [1 比 0 多的子数组个数](../../problems/count-subarrays-with-more-ones-than-zeros) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 1985 | [找出数组中的第 K 大整数](../../problems/find-the-kth-largest-integer-in-the-array) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1982 | [从子集的和还原数组](../../problems/find-array-given-subset-sums) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)]  | Hard |
-| 1901 | [找出顶峰元素 II](../../problems/find-a-peak-element-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1738 | [找出第 K 大的异或坐标值](../../problems/find-kth-largest-xor-coordinate-value) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[快速选择](../quickselect/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1649 | [通过指令创建有序数组](../../problems/create-sorted-array-through-instructions) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1382 | [将二叉搜索树变平衡](../../problems/balance-a-binary-search-tree) | [[贪心](../greedy/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1274 | [矩形内船只的数目](../../problems/number-of-ships-in-a-rectangle) 🔒 | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 973 | [最接近原点的 K 个点](../../problems/k-closest-points-to-origin) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 932 | [漂亮数组](../../problems/beautiful-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)]  | Medium |
-| 918 | [环形子数组的最大和](../../problems/maximum-sum-circular-subarray) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Medium |
-| 912 | [排序数组](../../problems/sort-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数排序](../counting-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 889 | [根据前序和后序遍历构造二叉树](../../problems/construct-binary-tree-from-preorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 654 | [最大二叉树](../../problems/maximum-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 558 | [四叉树交集](../../problems/logical-or-of-two-binary-grids-represented-as-quad-trees) | [[树](../tree/README.md)] [[分治](../divide-and-conquer/README.md)]  | Medium |
-| 493 | [翻转对](../../problems/reverse-pairs) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 427 | [建立四叉树](../../problems/construct-quad-tree) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 395 | [至少有 K 个重复字符的最长子串](../../problems/longest-substring-with-at-least-k-repeating-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 372 | [超级次方](../../problems/super-pow) | [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)]  | Medium |
-| 347 | [前 K 个高频元素](../../problems/top-k-frequent-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 327 | [区间和的个数](../../problems/count-of-range-sum) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 324 | [摆动排序 II](../../problems/wiggle-sort-ii) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 315 | [计算右侧小于当前元素的个数](../../problems/count-of-smaller-numbers-after-self) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 240 | [搜索二维矩阵 II](../../problems/search-a-2d-matrix-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 218 | [天际线问题](../../problems/the-skyline-problem) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 215 | [数组中的第K个最大元素](../../problems/kth-largest-element-in-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 190 | [颠倒二进制位](../../problems/reverse-bits) | [[位运算](../bit-manipulation/README.md)] [[分治](../divide-and-conquer/README.md)]  | Easy |
-| 169 | [多数元素](../../problems/majority-element) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 148 | [排序链表](../../problems/sort-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)] [[分治](../divide-and-conquer/README.md)] [[排序](../sorting/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 109 | [有序链表转换二叉搜索树](../../problems/convert-sorted-list-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 108 | [将有序数组转换为二叉搜索树](../../problems/convert-sorted-array-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 106 | [从中序与后序遍历序列构造二叉树](../../problems/construct-binary-tree-from-inorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 105 | [从前序与中序遍历序列构造二叉树](../../problems/construct-binary-tree-from-preorder-and-inorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 53 | [最大子数组和](../../problems/maximum-subarray) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 23 | [合并K个升序链表](../../problems/merge-k-sorted-lists) | [[链表](../linked-list/README.md)] [[分治](../divide-and-conquer/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 4 | [寻找两个正序数组的中位数](../../problems/median-of-two-sorted-arrays) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)]  | Hard |
diff --git a/tag/doubly-linked-list/README.md b/tag/doubly-linked-list/README.md
deleted file mode 100644
index 2e57a2202..000000000
--- a/tag/doubly-linked-list/README.md
+++ /dev/null
@@ -1,18 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 双向链表
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1472 | [设计浏览器历史记录](../../problems/design-browser-history) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 716 | [最大栈](../../problems/max-stack) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)] [[有序集合](../ordered-set/README.md)]  | Easy |
-| 460 | [LFU 缓存](../../problems/lfu-cache) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Hard |
-| 432 | [全 O(1) 的数据结构](../../problems/all-oone-data-structure) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Hard |
-| 430 | [扁平化多级双向链表](../../problems/flatten-a-multilevel-doubly-linked-list) | [[深度优先搜索](../depth-first-search/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 426 | [将二叉搜索树转化为排序的双向链表](../../problems/convert-binary-search-tree-to-sorted-doubly-linked-list) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 146 | [LRU 缓存](../../problems/lru-cache) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
diff --git a/tag/dynamic-programming/README.md b/tag/dynamic-programming/README.md
deleted file mode 100644
index 3e539a824..000000000
--- a/tag/dynamic-programming/README.md
+++ /dev/null
@@ -1,364 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 动态规划
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2172 | [数组的最大与和](../../problems/maximum-and-sum-of-array) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 2167 | [移除所有载有违禁货物车厢所需的最少时间](../../problems/minimum-time-to-remove-all-cars-containing-illegal-goods) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2163 | [删除元素后和的最小差值](../../problems/minimum-difference-in-sums-after-removal-of-elements) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 2152 | [Minimum Number of Lines to Cover Points](../../problems/minimum-number-of-lines-to-cover-points) 🔒 | [[位运算](../bit-manipulation/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 2147 | [分隔长廊的方案数](../../problems/number-of-ways-to-divide-a-long-corridor) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2143 | [Choose Numbers From Two Arrays in Range](../../problems/choose-numbers-from-two-arrays-in-range) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2140 | [解决智力问题](../../problems/solving-questions-with-brainpower) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2110 | [股票平滑下跌阶段的数目](../../problems/number-of-smooth-descent-periods-of-a-stock) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2100 | [适合打劫银行的日子](../../problems/find-good-days-to-rob-the-bank) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2088 | [统计农场中肥沃金字塔的数目](../../problems/count-fertile-pyramids-in-a-land) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 2086 | [从房屋收集雨水需要的最少水桶数](../../problems/minimum-number-of-buckets-required-to-collect-rainwater-from-houses) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2063 | [所有子字符串中的元音](../../problems/vowels-of-all-substrings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Medium |
-| 2060 | [同源字符串检测](../../problems/check-if-an-original-string-exists-given-two-encoded-strings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2054 | [两个最好的不重叠活动](../../problems/two-best-non-overlapping-events) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2052 | [将句子分隔成行的最低成本](../../problems/minimum-cost-to-separate-sentence-into-rows) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2050 | [并行课程 III](../../problems/parallel-courses-iii) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2036 | [最大交替子数组和](../../problems/maximum-alternating-subarray-sum) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2035 | [将数组分成两个数组并最小化数组和的差](../../problems/partition-array-into-two-arrays-to-minimize-sum-difference) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2019 | [解出数学表达式的学生分数](../../problems/the-score-of-students-solving-math-expression) | [[栈](../stack/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2008 | [出租车的最大盈利](../../problems/maximum-earnings-from-taxi) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2003 | [每棵子树内缺失的最小基因值](../../problems/smallest-missing-genetic-value-in-each-subtree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2002 | [两个回文子序列长度的最大乘积](../../problems/maximum-product-of-the-length-of-two-palindromic-subsequences) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1997 | [访问完所有房间的第一天](../../problems/first-day-where-you-have-been-in-all-the-rooms) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1994 | [好子集的数目](../../problems/the-number-of-good-subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1987 | [不同的好子序列数目](../../problems/number-of-unique-good-subsequences) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1986 | [完成任务的最少工作时间段](../../problems/minimum-number-of-work-sessions-to-finish-the-tasks) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1981 | [最小化目标值与所选元素的差](../../problems/minimize-the-difference-between-target-and-chosen-elements) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1977 | [划分数字的方案数](../../problems/number-of-ways-to-separate-numbers) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[后缀数组](../suffix-array/README.md)]  | Hard |
-| 1976 | [到达目的地的方案数](../../problems/number-of-ways-to-arrive-at-destination) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 1959 | [K 次调整数组大小浪费的最小总空间](../../problems/minimum-total-space-wasted-with-k-resizing-operations) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1955 | [统计特殊子序列的数目](../../problems/count-number-of-special-subsequences) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1947 | [最大兼容性评分和](../../problems/maximum-compatibility-score-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1931 | [用三种不同颜色为网格涂色](../../problems/painting-a-grid-with-three-different-colors) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1928 | [规定时间内到达终点的最小花费](../../problems/minimum-cost-to-reach-destination-in-time) | [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1916 | [统计为蚁群构筑房间的不同顺序](../../problems/count-ways-to-build-rooms-in-an-ant-colony) | [[树](../tree/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1911 | [最大子序列交替和](../../problems/maximum-alternating-subsequence-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1908 | [Nim 游戏 II](../../problems/game-of-nim) 🔒 | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1900 | [最佳运动员的比拼回合](../../problems/the-earliest-and-latest-rounds-where-players-compete) | [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1896 | [反转表达式值的最少操作次数](../../problems/minimum-cost-to-change-the-final-value-of-expression) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1884 | [鸡蛋掉落-两枚鸡蛋](../../problems/egg-drop-with-2-eggs-and-n-floors) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1883 | [准时抵达会议现场的最小跳过休息次数](../../problems/minimum-skips-to-arrive-at-meeting-on-time) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1879 | [两个数组最小的异或值之和](../../problems/minimum-xor-sum-of-two-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1872 | [石子游戏 VIII](../../problems/stone-game-viii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1866 | [恰有 K 根木棍可以看到的排列数目](../../problems/number-of-ways-to-rearrange-sticks-with-k-sticks-visible) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1857 | [有向图中最大颜色值](../../problems/largest-color-value-in-a-directed-graph) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)] [[计数](../counting/README.md)]  | Hard |
-| 1824 | [最少侧跳次数](../../problems/minimum-sideway-jumps) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1815 | [得到新鲜甜甜圈的最多组数](../../problems/maximum-number-of-groups-getting-fresh-donuts) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1799 | [N 次操作后的最大分数和](../../problems/maximize-score-after-n-operations) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1787 | [使所有区间的异或结果为零](../../problems/make-the-xor-of-all-segments-equal-to-zero) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1786 | [从第一个节点出发到最后一个节点的受限路径数](../../problems/number-of-restricted-paths-from-first-to-last-node) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1774 | [最接近目标价格的甜点成本](../../problems/closest-dessert-cost) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1771 | [由子序列构造的最长回文串的长度](../../problems/maximize-palindrome-length-from-subsequences) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1770 | [执行乘法运算的最大分数](../../problems/maximum-score-from-performing-multiplication-operations) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1755 | [最接近目标值的子序列和](../../problems/closest-subsequence-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1751 | [最多可以参加的会议数目 II](../../problems/maximum-number-of-events-that-can-be-attended-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1749 | [任意子数组和的绝对值的最大值](../../problems/maximum-absolute-sum-of-any-subarray) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1746 | [经过一次操作后的最大子数组和](../../problems/maximum-subarray-sum-after-one-operation) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1745 | [回文串分割 IV](../../problems/palindrome-partitioning-iv) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1735 | [生成乘积数组的方案数](../../problems/count-ways-to-make-array-with-product) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1728 | [猫和老鼠 II](../../problems/cat-and-mouse-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1723 | [完成所有工作的最短时间](../../problems/find-minimum-time-to-finish-all-jobs) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1714 | [数组中特殊等间距元素的和](../../problems/sum-of-special-evenly-spaced-elements-in-array) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1706 | [球会落何处](../../problems/where-will-the-ball-fall) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1696 | [跳跃游戏 VI](../../problems/jump-game-vi) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1692 | [计算分配糖果的不同方式](../../problems/count-ways-to-distribute-candies) 🔒 | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1691 | [堆叠长方体的最大高度](../../problems/maximum-height-by-stacking-cuboids) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1690 | [石子游戏 VII](../../problems/stone-game-vii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1687 | [从仓库到码头运输箱子](../../problems/delivering-boxes-from-storage-to-ports) | [[线段树](../segment-tree/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1682 | [最长回文子序列 II](../../problems/longest-palindromic-subsequence-ii) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1681 | [最小不兼容性](../../problems/minimum-incompatibility) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1671 | [得到山形数组的最少删除次数](../../problems/minimum-number-of-removals-to-make-mountain-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1664 | [生成平衡数组的方案数](../../problems/ways-to-make-a-fair-array) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1659 | [最大化网格幸福感](../../problems/maximize-grid-happiness) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1655 | [分配重复整数](../../problems/distribute-repeating-integers) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1654 | [到家的最少跳跃次数](../../problems/minimum-jumps-to-reach-home) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1653 | [使字符串平衡的最少删除次数](../../problems/minimum-deletions-to-make-string-balanced) | [[栈](../stack/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1646 | [获取生成数组中的最大值](../../problems/get-maximum-in-generated-array) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1643 | [第 K 条最小指令](../../problems/kth-smallest-instructions) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1641 | [统计字典序元音字符串的数目](../../problems/count-sorted-vowel-strings) | [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1639 | [通过给定词典构造目标字符串的方案数](../../problems/number-of-ways-to-form-a-target-string-given-a-dictionary) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1638 | [统计只差一个字符的子串数目](../../problems/count-substrings-that-differ-by-one-character) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1626 | [无矛盾的最佳球队](../../problems/best-team-with-no-conflicts) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1621 | [大小为 K 的不重叠线段的数目](../../problems/number-of-sets-of-k-non-overlapping-line-segments) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1617 | [统计子树中城市之间最大距离](../../problems/count-subtrees-with-max-distance-between-cities) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1611 | [使整数变为 0 的最少操作次数](../../problems/minimum-one-bit-operations-to-make-integers-zero) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1595 | [连通两组点的最小成本](../../problems/minimum-cost-to-connect-two-groups-of-points) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1594 | [矩阵的最大非负积](../../problems/maximum-non-negative-product-in-a-matrix) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1578 | [使绳子变成彩色的最短时间](../../problems/minimum-time-to-make-rope-colorful) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1575 | [统计所有可行路径](../../problems/count-all-possible-routes) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1567 | [乘积为正数的最长子数组长度](../../problems/maximum-length-of-subarray-with-positive-product) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1563 | [石子游戏 V](../../problems/stone-game-v) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1553 | [吃掉 N 个橘子的最少天数](../../problems/minimum-number-of-days-to-eat-n-oranges) | [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1548 | [图中最相似的路径](../../problems/the-most-similar-path-in-a-graph) 🔒 | [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1547 | [切棍子的最小成本](../../problems/minimum-cost-to-cut-a-stick) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1537 | [最大得分](../../problems/get-the-maximum-score) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1531 | [压缩字符串 II](../../problems/string-compression-ii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1526 | [形成目标数组的子数组最少增加次数](../../problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1525 | [字符串的好分割数目](../../problems/number-of-good-ways-to-split-a-string) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1524 | [和为奇数的子数组数目](../../problems/number-of-sub-arrays-with-odd-sum) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1510 | [石子游戏 IV](../../problems/stone-game-iv) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1504 | [统计全 1 子矩形](../../problems/count-submatrices-with-all-ones) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1494 | [并行课程 II](../../problems/parallel-courses-ii) | [[位运算](../bit-manipulation/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1493 | [删掉一个元素以后全为 1 的最长子数组](../../problems/longest-subarray-of-1s-after-deleting-one-element) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1483 | [树节点的第 K 个祖先](../../problems/kth-ancestor-of-a-tree-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1478 | [安排邮筒](../../problems/allocate-mailboxes) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1477 | [找两个和为目标值且不重叠的子数组](../../problems/find-two-non-overlapping-sub-arrays-each-with-target-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1473 | [粉刷房子 III](../../problems/paint-house-iii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1467 | [两个盒子中球的颜色数相同的概率](../../problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Hard |
-| 1463 | [摘樱桃 II](../../problems/cherry-pickup-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1458 | [两个子序列的最大点积](../../problems/max-dot-product-of-two-subsequences) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1449 | [数位成本和为目标值的最大数字](../../problems/form-largest-integer-with-digits-that-add-up-to-target) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1444 | [切披萨的方案数](../../problems/number-of-ways-of-cutting-a-pizza) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1434 | [每个人戴不同帽子的方案数](../../problems/number-of-ways-to-wear-different-hats-to-each-other) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1425 | [带限制的子序列和](../../problems/constrained-subsequence-sum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1420 | [生成数组](../../problems/build-array-where-you-can-find-the-maximum-exactly-k-comparisons) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1416 | [恢复数组](../../problems/restore-the-array) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1411 | [给 N x 3 网格图涂色的方案数](../../problems/number-of-ways-to-paint-n-3-grid) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1406 | [石子游戏 III](../../problems/stone-game-iii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1402 | [做菜顺序](../../problems/reducing-dishes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1397 | [找到所有好字符串](../../problems/find-all-good-strings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[字符串匹配](../string-matching/README.md)]  | Hard |
-| 1395 | [统计作战单位数](../../problems/count-number-of-teams) | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1388 | [3n 块披萨](../../problems/pizza-with-3n-slices) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1387 | [将整数按权重排序](../../problems/sort-integers-by-the-power-value) | [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1373 | [二叉搜索子树的最大键值和](../../problems/maximum-sum-bst-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1372 | [二叉树中的最长交错路径](../../problems/longest-zigzag-path-in-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1363 | [形成三的最大倍数](../../problems/largest-multiple-of-three) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1359 | [有效的快递序列数目](../../problems/count-all-valid-pickup-and-delivery-options) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1349 | [参加考试的最大学生数](../../problems/maximum-students-taking-exam) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1340 | [跳跃游戏 V](../../problems/jump-game-v) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1335 | [工作计划的最低难度](../../problems/minimum-difficulty-of-a-job-schedule) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1334 | [阈值距离内邻居最少的城市](../../problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance) | [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 1326 | [灌溉花园的最少水龙头数目](../../problems/minimum-number-of-taps-to-open-to-water-a-garden) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1320 | [二指输入的的最小距离](../../problems/minimum-distance-to-type-a-word-using-two-fingers) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1316 | [不同的循环子字符串](../../problems/distinct-echo-substrings) | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1312 | [让字符串成为回文串的最少插入次数](../../problems/minimum-insertion-steps-to-make-a-string-palindrome) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1301 | [最大得分的路径数目](../../problems/number-of-paths-with-max-score) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1289 | [下降路径最小和  II](../../problems/minimum-falling-path-sum-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1278 | [分割回文串 III](../../problems/palindrome-partitioning-iii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1277 | [统计全为 1 的正方形子矩阵](../../problems/count-square-submatrices-with-all-ones) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1269 | [停在原地的方案数](../../problems/number-of-ways-to-stay-in-the-same-place-after-some-steps) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1262 | [可被三整除的最大和](../../problems/greatest-sum-divisible-by-three) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1259 | [不相交的握手](../../problems/handshakes-that-dont-cross) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1255 | [得分最高的单词集合](../../problems/maximum-score-words-formed-by-letters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1246 | [删除回文子数组](../../problems/palindrome-removal) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1240 | [铺瓷砖](../../problems/tiling-a-rectangle-with-the-fewest-squares) | [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1235 | [规划兼职工作](../../problems/maximum-profit-in-job-scheduling) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1230 | [抛掷硬币](../../problems/toss-strange-coins) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 1227 | [飞机座位分配概率](../../problems/airplane-seat-assignment-probability) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 1223 | [掷骰子模拟](../../problems/dice-roll-simulation) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1220 | [统计元音字母序列的数目](../../problems/count-vowels-permutation) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1218 | [最长定差子序列](../../problems/longest-arithmetic-subsequence-of-given-difference) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1216 | [验证回文字符串 III](../../problems/valid-palindrome-iii) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1191 | [K 次串联后最大子数组之和](../../problems/k-concatenation-maximum-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1187 | [使数组严格递增](../../problems/make-array-strictly-increasing) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1186 | [删除一次得到子数组最大和](../../problems/maximum-subarray-sum-with-one-deletion) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1182 | [与目标颜色间的最短距离](../../problems/shortest-distance-to-target-color) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1162 | [地图分析](../../problems/as-far-from-land-as-possible) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1155 | [掷骰子的N种方法](../../problems/number-of-dice-rolls-with-target-sum) | [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1147 | [段式回文](../../problems/longest-chunked-palindrome-decomposition) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1143 | [最长公共子序列](../../problems/longest-common-subsequence) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1140 | [石子游戏 II](../../problems/stone-game-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1139 | [最大的以 1 为边界的正方形](../../problems/largest-1-bordered-square) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1137 | [第 N 个泰波那契数](../../problems/n-th-tribonacci-number) | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 1130 | [叶值的最小代价生成树](../../problems/minimum-cost-tree-from-leaf-values) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1125 | [最小的必要团队](../../problems/smallest-sufficient-team) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1105 | [填充书架](../../problems/filling-bookcase-shelves) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1092 | [最短公共超序列](../../problems/shortest-common-supersequence) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1067 | [范围内的数字计数](../../problems/digit-count-in-range) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1066 | [校园自行车分配 II](../../problems/campus-bikes-ii) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 1062 | [最长重复子串](../../problems/longest-repeating-substring) 🔒 | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1055 | [形成字符串的最短路径](../../problems/shortest-way-to-form-string) 🔒 | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1049 | [最后一块石头的重量 II](../../problems/last-stone-weight-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1048 | [最长字符串链](../../problems/longest-string-chain) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1043 | [分隔数组以得到最大和](../../problems/partition-array-for-maximum-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1039 | [多边形三角剖分的最低得分](../../problems/minimum-score-triangulation-of-polygon) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1035 | [不相交的线](../../problems/uncrossed-lines) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1031 | [两个非重叠子数组的最大和](../../problems/maximum-sum-of-two-non-overlapping-subarrays) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1027 | [最长等差数列](../../problems/longest-arithmetic-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1025 | [除数博弈](../../problems/divisor-game) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Easy |
-| 1024 | [视频拼接](../../problems/video-stitching) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1014 | [最佳观光组合](../../problems/best-sightseeing-pair) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1012 | [至少有 1 位重复的数字](../../problems/numbers-with-repeated-digits) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1000 | [合并石头的最低成本](../../problems/minimum-cost-to-merge-stones) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 996 | [正方形数组的数目](../../problems/number-of-squareful-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 983 | [最低票价](../../problems/minimum-cost-for-tickets) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 978 | [最长湍流子数组](../../problems/longest-turbulent-subarray) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 975 | [奇偶跳](../../problems/odd-even-jump) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 968 | [监控二叉树](../../problems/binary-tree-cameras) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 964 | [表示数字的最少运算符](../../problems/least-operators-to-express-number) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 960 | [删列造序 III](../../problems/delete-columns-to-make-sorted-iii) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 956 | [最高的广告牌](../../problems/tallest-billboard) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 943 | [最短超级串](../../problems/find-the-shortest-superstring) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 940 | [不同的子序列 II](../../problems/distinct-subsequences-ii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 935 | [骑士拨号器](../../problems/knight-dialer) | [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 931 | [下降路径最小和](../../problems/minimum-falling-path-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 926 | [将字符串翻转到单调递增](../../problems/flip-string-to-monotone-increasing) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 920 | [播放列表的数量](../../problems/number-of-music-playlists) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 918 | [环形子数组的最大和](../../problems/maximum-sum-circular-subarray) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Medium |
-| 913 | [猫和老鼠](../../problems/cat-and-mouse) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 907 | [子数组的最小值之和](../../problems/sum-of-subarray-minimums) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 903 | [DI 序列的有效排列](../../problems/valid-permutations-for-di-sequence) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 902 | [最大为 N 的数字组合](../../problems/numbers-at-most-n-given-digit-set) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 898 | [子数组按位或操作](../../problems/bitwise-ors-of-subarrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 894 | [所有可能的满二叉树](../../problems/all-possible-full-binary-trees) | [[树](../tree/README.md)] [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 887 | [鸡蛋掉落](../../problems/super-egg-drop) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 879 | [盈利计划](../../problems/profitable-schemes) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 877 | [石子游戏](../../problems/stone-game) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 873 | [最长的斐波那契子序列的长度](../../problems/length-of-longest-fibonacci-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 871 | [最低加油次数](../../problems/minimum-number-of-refueling-stops) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 847 | [访问所有节点的最短路径](../../problems/shortest-path-visiting-all-nodes) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 845 | [数组中的最长山脉](../../problems/longest-mountain-in-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 838 | [推多米诺](../../problems/push-dominoes) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 837 | [新 21 点](../../problems/new-21-game) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 834 | [树中距离之和](../../problems/sum-of-distances-in-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 828 | [统计子串中的唯一字符](../../problems/count-unique-characters-of-all-substrings-of-a-given-string) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 823 | [带因子的二叉树](../../problems/binary-trees-with-factors) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 818 | [赛车](../../problems/race-car) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 813 | [最大平均值和的分组](../../problems/largest-sum-of-averages) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 808 | [分汤](../../problems/soup-servings) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 805 | [数组的均值分割](../../problems/split-array-with-same-average) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 801 | [使序列递增的最小交换次数](../../problems/minimum-swaps-to-make-sequences-increasing) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 799 | [香槟塔](../../problems/champagne-tower) | [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 790 | [多米诺和托米诺平铺](../../problems/domino-and-tromino-tiling) | [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 788 | [旋转数字](../../problems/rotated-digits) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 787 | [K 站中转内最便宜的航班](../../problems/cheapest-flights-within-k-stops) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 764 | [最大加号标志](../../problems/largest-plus-sign) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 750 | [角矩形的数量](../../problems/number-of-corner-rectangles) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 746 | [使用最小花费爬楼梯](../../problems/min-cost-climbing-stairs) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 741 | [摘樱桃](../../problems/cherry-pickup) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 740 | [删除并获得点数](../../problems/delete-and-earn) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 730 | [统计不同回文子序列](../../problems/count-different-palindromic-subsequences) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 727 | [最小窗口子序列](../../problems/minimum-window-subsequence) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 718 | [最长重复子数组](../../problems/maximum-length-of-repeated-subarray) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 714 | [买卖股票的最佳时机含手续费](../../problems/best-time-to-buy-and-sell-stock-with-transaction-fee) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 712 | [两个字符串的最小ASCII删除和](../../problems/minimum-ascii-delete-sum-for-two-strings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 698 | [划分为k个相等的子集](../../problems/partition-to-k-equal-sum-subsets) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 691 | [贴纸拼词](../../problems/stickers-to-spell-word) | [[位运算](../bit-manipulation/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 689 | [三个无重叠子数组的最大和](../../problems/maximum-sum-of-3-non-overlapping-subarrays) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 688 | [骑士在棋盘上的概率](../../problems/knight-probability-in-chessboard) | [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 678 | [有效的括号字符串](../../problems/valid-parenthesis-string) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 673 | [最长递增子序列的个数](../../problems/number-of-longest-increasing-subsequence) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 664 | [奇怪的打印机](../../problems/strange-printer) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 656 | [金币路径](../../problems/coin-path) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 651 | [4键键盘](../../problems/4-keys-keyboard) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 650 | [只有两个键的键盘](../../problems/2-keys-keyboard) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 647 | [回文子串](../../problems/palindromic-substrings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 646 | [最长数对链](../../problems/maximum-length-of-pair-chain) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 639 | [解码方法 II](../../problems/decode-ways-ii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 638 | [大礼包](../../problems/shopping-offers) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 634 | [寻找数组的错位排列](../../problems/find-the-derangement-of-an-array) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 629 | [K个逆序对数组](../../problems/k-inverse-pairs-array) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 600 | [不含连续1的非负整数](../../problems/non-negative-integers-without-consecutive-ones) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 583 | [两个字符串的删除操作](../../problems/delete-operation-for-two-strings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 576 | [出界的路径数](../../problems/out-of-boundary-paths) | [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 568 | [最大休假天数](../../problems/maximum-vacation-days) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 562 | [矩阵中最长的连续1线段](../../problems/longest-line-of-consecutive-one-in-matrix) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 553 | [最优除法](../../problems/optimal-division) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 552 | [学生出勤记录 II](../../problems/student-attendance-record-ii) | [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 546 | [移除盒子](../../problems/remove-boxes) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 542 | [01 矩阵](../../problems/01-matrix) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 526 | [优美的排列](../../problems/beautiful-arrangement) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 518 | [零钱兑换 II](../../problems/coin-change-2) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 516 | [最长回文子序列](../../problems/longest-palindromic-subsequence) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 514 | [自由之路](../../problems/freedom-trail) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 509 | [斐波那契数](../../problems/fibonacci-number) | [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 494 | [目标和](../../problems/target-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 488 | [祖玛游戏](../../problems/zuma-game) | [[广度优先搜索](../breadth-first-search/README.md)] [[记忆化搜索](../memoization/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 487 | [最大连续1的个数 II](../../problems/max-consecutive-ones-ii) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 486 | [预测赢家](../../problems/predict-the-winner) | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 474 | [一和零](../../problems/ones-and-zeroes) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 473 | [火柴拼正方形](../../problems/matchsticks-to-square) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 472 | [连接词](../../problems/concatenated-words) | [[深度优先搜索](../depth-first-search/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 471 | [编码最短长度的字符串](../../problems/encode-string-with-shortest-length) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 467 | [环绕字符串中唯一的子字符串](../../problems/unique-substrings-in-wraparound-string) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 466 | [统计重复个数](../../problems/count-the-repetitions) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 464 | [我能赢吗](../../problems/can-i-win) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 458 | [可怜的小猪](../../problems/poor-pigs) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 446 | [等差数列划分 II - 子序列](../../problems/arithmetic-slices-ii-subsequence) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 435 | [无重叠区间](../../problems/non-overlapping-intervals) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 418 | [屏幕可显示句子的数量](../../problems/sentence-screen-fitting) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 416 | [分割等和子集](../../problems/partition-equal-subset-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 413 | [等差数列划分](../../problems/arithmetic-slices) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 410 | [分割数组的最大值](../../problems/split-array-largest-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 403 | [青蛙过河](../../problems/frog-jump) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 397 | [整数替换](../../problems/integer-replacement) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 396 | [旋转函数](../../problems/rotate-function) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 392 | [判断子序列](../../problems/is-subsequence) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 377 | [组合总和 Ⅳ](../../problems/combination-sum-iv) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 376 | [摆动序列](../../problems/wiggle-subsequence) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 375 | [猜数字大小 II](../../problems/guess-number-higher-or-lower-ii) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 368 | [最大整除子集](../../problems/largest-divisible-subset) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 363 | [矩形区域不超过 K 的最大数值和](../../problems/max-sum-of-rectangle-no-larger-than-k) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 361 | [轰炸敌人](../../problems/bomb-enemy) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 357 | [计算各个位数不同的数字个数](../../problems/count-numbers-with-unique-digits) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 354 | [俄罗斯套娃信封问题](../../problems/russian-doll-envelopes) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 351 | [安卓系统手势解锁](../../problems/android-unlock-patterns) 🔒 | [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 343 | [整数拆分](../../problems/integer-break) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 338 | [比特位计数](../../problems/counting-bits) | [[位运算](../bit-manipulation/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 337 | [打家劫舍 III](../../problems/house-robber-iii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 333 | [最大 BST 子树](../../problems/largest-bst-subtree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 329 | [矩阵中的最长递增路径](../../problems/longest-increasing-path-in-a-matrix) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 322 | [零钱兑换](../../problems/coin-change) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 313 | [超级丑数](../../problems/super-ugly-number) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 312 | [戳气球](../../problems/burst-balloons) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 309 | [最佳买卖股票时机含冷冻期](../../problems/best-time-to-buy-and-sell-stock-with-cooldown) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 300 | [最长递增子序列](../../problems/longest-increasing-subsequence) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 294 | [翻转游戏 II](../../problems/flip-game-ii) 🔒 | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 279 | [完全平方数](../../problems/perfect-squares) | [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 276 | [栅栏涂色](../../problems/paint-fence) 🔒 | [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 265 | [粉刷房子 II](../../problems/paint-house-ii) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 264 | [丑数 II](../../problems/ugly-number-ii) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 256 | [粉刷房子](../../problems/paint-house) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 241 | [为运算表达式设计优先级](../../problems/different-ways-to-add-parentheses) | [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 233 | [数字 1 的个数](../../problems/number-of-digit-one) | [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 221 | [最大正方形](../../problems/maximal-square) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 213 | [打家劫舍 II](../../problems/house-robber-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 198 | [打家劫舍](../../problems/house-robber) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 188 | [买卖股票的最佳时机 IV](../../problems/best-time-to-buy-and-sell-stock-iv) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 174 | [地下城游戏](../../problems/dungeon-game) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 152 | [乘积最大子数组](../../problems/maximum-product-subarray) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 140 | [单词拆分 II](../../problems/word-break-ii) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 139 | [单词拆分](../../problems/word-break) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 132 | [分割回文串 II](../../problems/palindrome-partitioning-ii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 131 | [分割回文串](../../problems/palindrome-partitioning) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 124 | [二叉树中的最大路径和](../../problems/binary-tree-maximum-path-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 123 | [买卖股票的最佳时机 III](../../problems/best-time-to-buy-and-sell-stock-iii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 122 | [买卖股票的最佳时机 II](../../problems/best-time-to-buy-and-sell-stock-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 121 | [买卖股票的最佳时机](../../problems/best-time-to-buy-and-sell-stock) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 120 | [三角形最小路径和](../../problems/triangle) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 119 | [杨辉三角 II](../../problems/pascals-triangle-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 118 | [杨辉三角](../../problems/pascals-triangle) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 115 | [不同的子序列](../../problems/distinct-subsequences) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 97 | [交错字符串](../../problems/interleaving-string) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 96 | [不同的二叉搜索树](../../problems/unique-binary-search-trees) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 95 | [不同的二叉搜索树 II](../../problems/unique-binary-search-trees-ii) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 91 | [解码方法](../../problems/decode-ways) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 87 | [扰乱字符串](../../problems/scramble-string) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 85 | [最大矩形](../../problems/maximal-rectangle) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 72 | [编辑距离](../../problems/edit-distance) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 70 | [爬楼梯](../../problems/climbing-stairs) | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 64 | [最小路径和](../../problems/minimum-path-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 63 | [不同路径 II](../../problems/unique-paths-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 62 | [不同路径](../../problems/unique-paths) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Medium |
-| 55 | [跳跃游戏](../../problems/jump-game) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 53 | [最大子数组和](../../problems/maximum-subarray) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 45 | [跳跃游戏 II](../../problems/jump-game-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 44 | [通配符匹配](../../problems/wildcard-matching) | [[贪心](../greedy/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 42 | [接雨水](../../problems/trapping-rain-water) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 32 | [最长有效括号](../../problems/longest-valid-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 22 | [括号生成](../../problems/generate-parentheses) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 10 | [正则表达式匹配](../../problems/regular-expression-matching) | [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 5 | [最长回文子串](../../problems/longest-palindromic-substring) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
diff --git a/tag/enumeration/README.md b/tag/enumeration/README.md
deleted file mode 100644
index ff12a4344..000000000
--- a/tag/enumeration/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 枚举
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2162 | [设置时间的最少代价](../../problems/minimum-cost-to-set-cooking-time) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 2151 | [基于陈述统计最多好人数](../../problems/maximum-good-people-based-on-statements) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2122 | [还原原数组](../../problems/recover-the-original-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2094 | [找出 3 位偶数](../../problems/finding-3-digit-even-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2081 | [k 镜像数字的和](../../problems/sum-of-k-mirror-numbers) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2048 | [下一个更大的数值平衡数](../../problems/next-greater-numerically-balanced-number) | [[数学](../math/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 2025 | [分割数组的最多方案数](../../problems/maximum-number-of-ways-to-partition-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 2018 | [判断单词是否能放入填字游戏内](../../problems/check-if-word-can-be-placed-in-crossword) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2014 | [重复 K 次的最长子序列](../../problems/longest-subsequence-repeated-k-times) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1995 | [统计特殊四元组](../../problems/count-special-quadruplets) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 1958 | [检查操作是否合法](../../problems/check-if-move-is-legal) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1956 | [感染 K 种病毒所需的最短时间](../../problems/minimum-time-for-k-virus-variants-to-spread) 🔒 | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1925 | [统计平方和三元组的数目](../../problems/count-square-sum-triples) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 1620 | [网络信号最好的坐标](../../problems/coordinate-with-maximum-network-quality) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 1617 | [统计子树中城市之间最大距离](../../problems/count-subtrees-with-max-distance-between-cities) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1601 | [最多可达成的换楼请求数目](../../problems/maximum-number-of-achievable-transfer-requests) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1566 | [重复至少 K 次且长度为 M 的模式](../../problems/detect-pattern-of-length-m-repeated-k-or-more-times) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 1534 | [统计好三元组](../../problems/count-good-triplets) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 1291 | [顺次数](../../problems/sequential-digits) | [[枚举](../enumeration/README.md)]  | Medium |
-| 949 | [给定数字能组成的最大时间](../../problems/largest-time-for-given-digits) | [[字符串](../string/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 906 | [超级回文数](../../problems/super-palindromes) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 869 | [重新排序得到 2 的幂](../../problems/reordered-power-of-2) | [[数学](../math/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 845 | [数组中的最长山脉](../../problems/longest-mountain-in-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 829 | [连续整数求和](../../problems/consecutive-numbers-sum) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 800 | [相似 RGB 颜色](../../problems/similar-rgb-color) 🔒 | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 681 | [最近时刻](../../problems/next-closest-time) 🔒 | [[字符串](../string/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 204 | [计数质数](../../problems/count-primes) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[枚举](../enumeration/README.md)] [[数论](../number-theory/README.md)]  | Medium |
diff --git a/tag/eulerian-circuit/README.md b/tag/eulerian-circuit/README.md
deleted file mode 100644
index a616dce95..000000000
--- a/tag/eulerian-circuit/README.md
+++ /dev/null
@@ -1,14 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 欧拉回路
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2097 | [合法重新排列数对](../../problems/valid-arrangement-of-pairs) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[欧拉回路](../eulerian-circuit/README.md)]  | Hard |
-| 753 | [破解保险箱](../../problems/cracking-the-safe) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[欧拉回路](../eulerian-circuit/README.md)]  | Hard |
-| 332 | [重新安排行程](../../problems/reconstruct-itinerary) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[欧拉回路](../eulerian-circuit/README.md)]  | Hard |
diff --git a/tag/game-theory/README.md b/tag/game-theory/README.md
deleted file mode 100644
index 50c4354cf..000000000
--- a/tag/game-theory/README.md
+++ /dev/null
@@ -1,34 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 博弈
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2038 | [如果相邻两个颜色均相同则删除当前颜色](../../problems/remove-colored-pieces-if-both-neighbors-are-the-same-color) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 2029 | [石子游戏 IX](../../problems/stone-game-ix) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1927 | [求和游戏](../../problems/sum-game) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1908 | [Nim 游戏 II](../../problems/game-of-nim) 🔒 | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1872 | [石子游戏 VIII](../../problems/stone-game-viii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1728 | [猫和老鼠 II](../../problems/cat-and-mouse-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1690 | [石子游戏 VII](../../problems/stone-game-vii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1686 | [石子游戏 VI](../../problems/stone-game-vi) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1563 | [石子游戏 V](../../problems/stone-game-v) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1561 | [你可以获得的最大硬币数目](../../problems/maximum-number-of-coins-you-can-get) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1510 | [石子游戏 IV](../../problems/stone-game-iv) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1406 | [石子游戏 III](../../problems/stone-game-iii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1140 | [石子游戏 II](../../problems/stone-game-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1025 | [除数博弈](../../problems/divisor-game) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Easy |
-| 913 | [猫和老鼠](../../problems/cat-and-mouse) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 877 | [石子游戏](../../problems/stone-game) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 843 | [猜猜这个单词](../../problems/guess-the-word) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[博弈](../game-theory/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 810 | [黑板异或游戏](../../problems/chalkboard-xor-game) | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 486 | [预测赢家](../../problems/predict-the-winner) | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 464 | [我能赢吗](../../problems/can-i-win) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 375 | [猜数字大小 II](../../problems/guess-number-higher-or-lower-ii) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 294 | [翻转游戏 II](../../problems/flip-game-ii) 🔒 | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 292 | [Nim 游戏](../../problems/nim-game) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Easy |
diff --git a/tag/geometry/README.md b/tag/geometry/README.md
deleted file mode 100644
index e2465ee41..000000000
--- a/tag/geometry/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 几何
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2152 | [Minimum Number of Lines to Cover Points](../../problems/minimum-number-of-lines-to-cover-points) 🔒 | [[位运算](../bit-manipulation/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 2101 | [引爆最多的炸弹](../../problems/detonate-the-maximum-bombs) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1956 | [感染 K 种病毒所需的最短时间](../../problems/minimum-time-for-k-virus-variants-to-spread) 🔒 | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1924 | [安装栅栏 II](../../problems/erect-the-fence-ii) 🔒 | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1828 | [统计一个圆中点的数目](../../problems/queries-on-number-of-points-inside-a-circle) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1610 | [可见点的最大数目](../../problems/maximum-number-of-visible-points) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 1515 | [服务中心的最佳位置](../../problems/best-position-for-a-service-centre) | [[几何](../geometry/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 1453 | [圆形靶内的最大飞镖数量](../../problems/maximum-number-of-darts-inside-of-a-circular-dartboard) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1401 | [圆和矩形是否有重叠](../../problems/circle-and-rectangle-overlapping) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1266 | [访问所有点的最小时间](../../problems/minimum-time-visiting-all-points) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1232 | [缀点成线](../../problems/check-if-it-is-a-straight-line) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1037 | [有效的回旋镖](../../problems/valid-boomerang) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1030 | [距离顺序排列矩阵单元格](../../problems/matrix-cells-in-distance-order) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 973 | [最接近原点的 K 个点](../../problems/k-closest-points-to-origin) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 963 | [最小面积矩形 II](../../problems/minimum-area-rectangle-ii) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 939 | [最小面积矩形](../../problems/minimum-area-rectangle) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 892 | [三维形体的表面积](../../problems/surface-area-of-3d-shapes) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 883 | [三维形体投影面积](../../problems/projection-area-of-3d-shapes) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 858 | [镜面反射](../../problems/mirror-reflection) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 836 | [矩形重叠](../../problems/rectangle-overlap) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Easy |
-| 812 | [最大三角形面积](../../problems/largest-triangle-area) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 593 | [有效的正方形](../../problems/valid-square) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 587 | [安装栅栏](../../problems/erect-the-fence) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 478 | [在圆内随机生成点](../../problems/generate-random-point-in-a-circle) | [[几何](../geometry/README.md)] [[数学](../math/README.md)] [[拒绝采样](../rejection-sampling/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 469 | [凸多边形](../../problems/convex-polygon) 🔒 | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 335 | [路径交叉](../../problems/self-crossing) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 223 | [矩形面积](../../problems/rectangle-area) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 149 | [直线上最多的点数](../../problems/max-points-on-a-line) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Hard |
diff --git a/tag/graph/README.md b/tag/graph/README.md
deleted file mode 100644
index 7fb9edbc3..000000000
--- a/tag/graph/README.md
+++ /dev/null
@@ -1,100 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 图
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2127 | [参加会议的最多员工数](../../problems/maximum-employees-to-be-invited-to-a-meeting) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 2123 | [Minimum Operations to Remove Adjacent Ones in Matrix](../../problems/minimum-operations-to-remove-adjacent-ones-in-matrix) 🔒 | [[图](../graph/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 2115 | [从给定原材料中找到所有可以做出的菜](../../problems/find-all-possible-recipes-from-given-supplies) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2101 | [引爆最多的炸弹](../../problems/detonate-the-maximum-bombs) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 2097 | [合法重新排列数对](../../problems/valid-arrangement-of-pairs) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[欧拉回路](../eulerian-circuit/README.md)]  | Hard |
-| 2093 | [Minimum Cost to Reach City With Discounts](../../problems/minimum-cost-to-reach-city-with-discounts) 🔒 | [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 2092 | [找出知晓秘密的所有专家](../../problems/find-all-people-with-secret) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2077 | [Paths in Maze That Lead to Same Room](../../problems/paths-in-maze-that-lead-to-same-room) 🔒 | [[图](../graph/README.md)]  | Medium |
-| 2076 | [处理含限制条件的好友请求](../../problems/process-restricted-friend-requests) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 2065 | [最大化一张图中的路径价值](../../problems/maximum-path-quality-of-a-graph) | [[图](../graph/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 2050 | [并行课程 III](../../problems/parallel-courses-iii) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2045 | [到达目的地的第二短时间](../../problems/second-minimum-time-to-reach-destination) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)]  | Hard |
-| 2039 | [网络空闲的时刻](../../problems/the-time-when-the-network-becomes-idle) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1976 | [到达目的地的方案数](../../problems/number-of-ways-to-arrive-at-destination) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 1971 | [寻找图中是否存在路径](../../problems/find-if-path-exists-in-graph) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Easy |
-| 1928 | [规定时间内到达终点的最小花费](../../problems/minimum-cost-to-reach-destination-in-time) | [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1916 | [统计为蚁群构筑房间的不同顺序](../../problems/count-ways-to-build-rooms-in-an-ant-colony) | [[树](../tree/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1857 | [有向图中最大颜色值](../../problems/largest-color-value-in-a-directed-graph) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)] [[计数](../counting/README.md)]  | Hard |
-| 1810 | [隐藏网格下的最小消耗路径](../../problems/minimum-path-cost-in-a-hidden-grid) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[交互](../interactive/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1791 | [找出星型图的中心节点](../../problems/find-center-of-star-graph) | [[图](../graph/README.md)]  | Easy |
-| 1786 | [从第一个节点出发到最后一个节点的受限路径数](../../problems/number-of-restricted-paths-from-first-to-last-node) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1782 | [统计点对的数目](../../problems/count-pairs-of-nodes) | [[图](../graph/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1778 | [未知网格中的最短路径](../../problems/shortest-path-in-a-hidden-grid) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1761 | [一个图中连通三元组的最小度数](../../problems/minimum-degree-of-a-connected-trio-in-a-graph) | [[图](../graph/README.md)]  | Hard |
-| 1728 | [猫和老鼠 II](../../problems/cat-and-mouse-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1724 | [检查边长度限制的路径是否存在 II](../../problems/checking-existence-of-edge-length-limited-paths-ii) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)]  | Hard |
-| 1719 | [重构一棵树的方案数](../../problems/number-of-ways-to-reconstruct-a-tree) | [[树](../tree/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 1697 | [检查边长度限制的路径是否存在](../../problems/checking-existence-of-edge-length-limited-paths) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1632 | [矩阵转换后的秩](../../problems/rank-transform-of-a-matrix) | [[贪心](../greedy/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1615 | [最大网络秩](../../problems/maximal-network-rank) | [[图](../graph/README.md)]  | Medium |
-| 1591 | [奇怪的打印机 II](../../problems/strange-printer-ii) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1579 | [保证图可完全遍历](../../problems/remove-max-number-of-edges-to-keep-graph-fully-traversable) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 1557 | [可以到达所有点的最少点数目](../../problems/minimum-number-of-vertices-to-reach-all-nodes) | [[图](../graph/README.md)]  | Medium |
-| 1548 | [图中最相似的路径](../../problems/the-most-similar-path-in-a-graph) 🔒 | [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1514 | [概率最大的路径](../../problems/path-with-maximum-probability) | [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1494 | [并行课程 II](../../problems/parallel-courses-ii) | [[位运算](../bit-manipulation/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1489 | [找到最小生成树里的关键边和伪关键边](../../problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)] [[排序](../sorting/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
-| 1466 | [重新规划路线](../../problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1462 | [课程表 IV](../../problems/course-schedule-iv) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 1377 | [T 秒后青蛙的位置](../../problems/frog-position-after-t-seconds) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Hard |
-| 1368 | [使网格图至少有一条有效路径的最小代价](../../problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1361 | [验证二叉树](../../problems/validate-binary-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1334 | [阈值距离内邻居最少的城市](../../problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance) | [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 1319 | [连通网络的操作次数](../../problems/number-of-operations-to-make-network-connected) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1203 | [项目管理](../../problems/sort-items-by-groups-respecting-dependencies) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 1192 | [查找集群内的「关键连接」](../../problems/critical-connections-in-a-network) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[双连通分量](../biconnected-component/README.md)]  | Hard |
-| 1168 | [水资源分配优化](../../problems/optimize-water-distribution-in-a-village) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)]  | Hard |
-| 1136 | [平行课程](../../problems/parallel-courses) 🔒 | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 1135 | [最低成本联通所有城市](../../problems/connecting-cities-with-minimum-cost) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1129 | [颜色交替的最短路径](../../problems/shortest-path-with-alternating-colors) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1059 | [从始点到终点的所有路径](../../problems/all-paths-from-source-lead-to-destination) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1042 | [不邻接植花](../../problems/flower-planting-with-no-adjacent) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 997 | [找到小镇的法官](../../problems/find-the-town-judge) | [[图](../graph/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 990 | [等式方程的可满足性](../../problems/satisfiability-of-equality-equations) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 959 | [由斜杠划分区域](../../problems/regions-cut-by-slashes) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 947 | [移除最多的同行或同列石头](../../problems/most-stones-removed-with-same-row-or-column) | [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 913 | [猫和老鼠](../../problems/cat-and-mouse) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 886 | [可能的二分法](../../problems/possible-bipartition) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 882 | [细分图中的可到达结点](../../problems/reachable-nodes-in-subdivided-graph) | [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 851 | [喧闹和富有](../../problems/loud-and-rich) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)]  | Medium |
-| 847 | [访问所有节点的最短路径](../../problems/shortest-path-visiting-all-nodes) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 841 | [钥匙和房间](../../problems/keys-and-rooms) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 834 | [树中距离之和](../../problems/sum-of-distances-in-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 802 | [找到最终的安全状态](../../problems/find-eventual-safe-states) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 797 | [所有可能的路径](../../problems/all-paths-from-source-to-target) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 787 | [K 站中转内最便宜的航班](../../problems/cheapest-flights-within-k-stops) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 785 | [判断二分图](../../problems/is-graph-bipartite) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 765 | [情侣牵手](../../problems/couples-holding-hands) | [[贪心](../greedy/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 753 | [破解保险箱](../../problems/cracking-the-safe) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[欧拉回路](../eulerian-circuit/README.md)]  | Hard |
-| 743 | [网络延迟时间](../../problems/network-delay-time) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 685 | [冗余连接 II](../../problems/redundant-connection-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 684 | [冗余连接](../../problems/redundant-connection) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 631 | [设计 Excel 求和公式](../../problems/design-excel-sum-formula) 🔒 | [[图](../graph/README.md)] [[设计](../design/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 547 | [省份数量](../../problems/number-of-provinces) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 505 | [迷宫 II](../../problems/the-maze-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 499 | [迷宫 III](../../problems/the-maze-iii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 490 | [迷宫](../../problems/the-maze) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Medium |
-| 444 | [序列重建](../../problems/sequence-reconstruction) 🔒 | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)]  | Medium |
-| 399 | [除法求值](../../problems/evaluate-division) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 332 | [重新安排行程](../../problems/reconstruct-itinerary) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[欧拉回路](../eulerian-circuit/README.md)]  | Hard |
-| 329 | [矩阵中的最长递增路径](../../problems/longest-increasing-path-in-a-matrix) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 323 | [无向图中连通分量的数目](../../problems/number-of-connected-components-in-an-undirected-graph) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 310 | [最小高度树](../../problems/minimum-height-trees) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 277 | [搜寻名人](../../problems/find-the-celebrity) 🔒 | [[贪心](../greedy/README.md)] [[图](../graph/README.md)] [[双指针](../two-pointers/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 269 | [火星词典](../../problems/alien-dictionary) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 261 | [以图判树](../../problems/graph-valid-tree) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 210 | [课程表 II](../../problems/course-schedule-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 207 | [课程表](../../problems/course-schedule) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 133 | [克隆图](../../problems/clone-graph) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
diff --git a/tag/greedy/README.md b/tag/greedy/README.md
deleted file mode 100644
index 273b006ac..000000000
--- a/tag/greedy/README.md
+++ /dev/null
@@ -1,233 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 贪心
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2170 | [使数组变成交替数组的最少操作数](../../problems/minimum-operations-to-make-the-array-alternating) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2160 | [拆分数位后四位数字的最小和](../../problems/minimum-sum-of-four-digit-number-after-splitting-digits) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2144 | [打折购买糖果的最小开销](../../problems/minimum-cost-of-buying-candies-with-discount) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2141 | [同时运行 N 台电脑的最长时间](../../problems/maximum-running-time-of-n-computers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2139 | [得到目标值的最少行动次数](../../problems/minimum-moves-to-reach-target-score) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 2136 | [全部开花的最早一天](../../problems/earliest-possible-day-of-full-bloom) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2132 | [用邮票贴满网格图](../../problems/stamping-the-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 2131 | [连接两字母单词得到的最长回文串](../../problems/longest-palindrome-by-concatenating-two-letter-words) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2126 | [摧毁小行星](../../problems/destroying-asteroids) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2116 | [判断一个括号字符串是否有效](../../problems/check-if-a-parentheses-string-can-be-valid) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2098 | [Subsequence of Size K With the Largest Even Sum](../../problems/subsequence-of-size-k-with-the-largest-even-sum) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2091 | [从数组中移除最大值和最小值](../../problems/removing-minimum-and-maximum-from-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 2087 | [网格图中机器人回家的最小代价](../../problems/minimum-cost-homecoming-of-a-robot-in-a-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2086 | [从房屋收集雨水需要的最少水桶数](../../problems/minimum-number-of-buckets-required-to-collect-rainwater-from-houses) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2078 | [两栋颜色不同且距离最远的房子](../../problems/two-furthest-houses-with-different-colors) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 2071 | [你可以安排的最多任务数目](../../problems/maximum-number-of-tasks-you-can-assign) | [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Hard |
-| 2038 | [如果相邻两个颜色均相同则删除当前颜色](../../problems/remove-colored-pieces-if-both-neighbors-are-the-same-color) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 2030 | [含特定字母的最小子序列](../../problems/smallest-k-length-subsequence-with-occurrences-of-a-letter) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 2029 | [石子游戏 IX](../../problems/stone-game-ix) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 2027 | [转换字符串的最少操作次数](../../problems/minimum-moves-to-convert-string) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2015 | [Average Height of Buildings in Each Segment](../../problems/average-height-of-buildings-in-each-segment) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2014 | [重复 K 次的最长子序列](../../problems/longest-subsequence-repeated-k-times) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2007 | [从双倍数组中还原原数组](../../problems/find-original-array-from-doubled-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1996 | [游戏中弱角色的数量](../../problems/the-number-of-weak-characters-in-the-game) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1975 | [最大方阵和](../../problems/maximum-matrix-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1974 | [使用特殊打字机键入单词的最少时间](../../problems/minimum-time-to-type-word-using-special-typewriter) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1969 | [数组元素的最小非零乘积](../../problems/minimum-non-zero-product-of-the-array-elements) | [[贪心](../greedy/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1968 | [构造元素不等于两相邻元素平均值的数组](../../problems/array-with-elements-not-equal-to-average-of-neighbors) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1963 | [使字符串平衡的最小交换次数](../../problems/minimum-number-of-swaps-to-make-the-string-balanced) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1953 | [你可以工作的最大周数](../../problems/maximum-number-of-weeks-for-which-you-can-work) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1946 | [子字符串突变后可能得到的最大整数](../../problems/largest-number-after-mutating-substring) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1936 | [新增的最少台阶数](../../problems/add-minimum-number-of-rungs) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1927 | [求和游戏](../../problems/sum-game) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1921 | [消灭怪物的最大数量](../../problems/eliminate-maximum-number-of-monsters) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1903 | [字符串中的最大奇数](../../problems/largest-odd-number-in-string) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1899 | [合并若干三元组以形成目标三元组](../../problems/merge-triplets-to-form-target-triplet) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1888 | [使二进制字符串字符交替的最少反转次数](../../problems/minimum-number-of-flips-to-make-the-binary-string-alternating) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1881 | [插入后的最大值](../../problems/maximum-value-after-insertion) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1877 | [数组中最大数对和的最小值](../../problems/minimize-maximum-pair-sum-in-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1874 | [两个数组的最小乘积和](../../problems/minimize-product-sum-of-two-arrays) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1864 | [构成交替字符串需要的最小交换次数](../../problems/minimum-number-of-swaps-to-make-the-binary-string-alternating) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1855 | [下标对中的最大距离](../../problems/maximum-distance-between-a-pair-of-values) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1850 | [邻位交换的最小次数](../../problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1846 | [减小和重新排列数组后的最大元素](../../problems/maximum-element-after-decreasing-and-rearranging) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1833 | [雪糕的最大数量](../../problems/maximum-ice-cream-bars) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1827 | [最少操作使数组递增](../../problems/minimum-operations-to-make-the-array-increasing) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 1824 | [最少侧跳次数](../../problems/minimum-sideway-jumps) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1802 | [有界数组中指定下标处的最大值](../../problems/maximum-value-at-a-given-index-in-a-bounded-array) | [[贪心](../greedy/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1798 | [你能构造出连续值的最大数目](../../problems/maximum-number-of-consecutive-values-you-can-make) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1794 | [统计距离最小的子串对个数](../../problems/count-pairs-of-equal-substrings-with-minimum-difference) 🔒 | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1792 | [最大平均通过率](../../problems/maximum-average-pass-ratio) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1788 | [最大化花园的美观度](../../problems/maximize-the-beauty-of-the-garden) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1785 | [构成特定和需要添加的最少元素](../../problems/minimum-elements-to-add-to-form-a-given-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1775 | [通过最少操作次数使数组的和相等](../../problems/equal-sum-arrays-with-minimum-number-of-operations) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1764 | [通过连接另一个数组的子数组得到一个数组](../../problems/form-array-by-concatenating-subarrays-of-another-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 1754 | [构造字典序最大的合并字符串](../../problems/largest-merge-of-two-strings) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1753 | [移除石子的最大得分](../../problems/maximum-score-from-removing-stones) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1739 | [放置盒子](../../problems/building-boxes) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1733 | [需要教语言的最少人数](../../problems/minimum-number-of-people-to-teach) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1727 | [重新排列后的最大子矩阵](../../problems/largest-submatrix-with-rearrangements) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1717 | [删除子字符串的最大得分](../../problems/maximum-score-from-removing-substrings) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1713 | [得到子序列的最少操作次数](../../problems/minimum-operations-to-make-a-subsequence) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1710 | [卡车上的最大单元数](../../problems/maximum-units-on-a-truck) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1708 | [长度为 K 的最大子数组](../../problems/largest-subarray-length-k) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 1705 | [吃苹果的最大数目](../../problems/maximum-number-of-eaten-apples) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1703 | [得到连续 K 个 1 的最少相邻交换次数](../../problems/minimum-adjacent-swaps-for-k-consecutive-ones) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 1702 | [修改后的最大二进制字符串](../../problems/maximum-binary-string-after-change) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1689 | [十-二进制数的最少数目](../../problems/partitioning-into-minimum-number-of-deci-binary-numbers) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1686 | [石子游戏 VI](../../problems/stone-game-vi) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1675 | [数组的最小偏移量](../../problems/minimize-deviation-in-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1673 | [找出最具竞争力的子序列](../../problems/find-the-most-competitive-subsequence) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1671 | [得到山形数组的最少删除次数](../../problems/minimum-number-of-removals-to-make-mountain-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1665 | [完成所有任务的最少初始能量](../../problems/minimum-initial-energy-to-finish-tasks) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1663 | [具有给定数值的最小字符串](../../problems/smallest-string-with-a-given-numeric-value) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1648 | [销售价值减少的颜色球](../../problems/sell-diminishing-valued-colored-balls) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1647 | [字符频次唯一的最小删除次数](../../problems/minimum-deletions-to-make-character-frequencies-unique) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1642 | [可以到达的最远建筑](../../problems/furthest-building-you-can-reach) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1632 | [矩阵转换后的秩](../../problems/rank-transform-of-a-matrix) | [[贪心](../greedy/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1616 | [分割两个字符串得到回文串](../../problems/split-two-strings-to-make-palindrome) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1606 | [找到处理最多请求的服务器](../../problems/find-servers-that-handled-most-number-of-requests) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1605 | [给定行和列的和求可行矩阵](../../problems/find-valid-matrix-given-row-and-column-sums) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1589 | [所有排列中的最大和](../../problems/maximum-sum-obtained-of-any-permutation) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1585 | [检查字符串是否可以通过排序子字符串得到另一个字符串](../../problems/check-if-string-is-transformable-with-substring-sort-operations) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1580 | [把箱子放进仓库里 II](../../problems/put-boxes-into-the-warehouse-ii) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1578 | [使绳子变成彩色的最短时间](../../problems/minimum-time-to-make-rope-colorful) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1567 | [乘积为正数的最长子数组长度](../../problems/maximum-length-of-subarray-with-positive-product) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1564 | [把箱子放进仓库里 I](../../problems/put-boxes-into-the-warehouse-i) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1561 | [你可以获得的最大硬币数目](../../problems/maximum-number-of-coins-you-can-get) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1558 | [得到目标数组的最少函数调用次数](../../problems/minimum-numbers-of-function-calls-to-make-target-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1546 | [和为目标值且不重叠的非空子数组的最大数目](../../problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1541 | [平衡括号字符串的最少插入次数](../../problems/minimum-insertions-to-balance-a-parentheses-string) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1537 | [最大得分](../../problems/get-the-maximum-score) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1536 | [排布二进制网格的最少交换次数](../../problems/minimum-swaps-to-arrange-a-binary-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1529 | [最少的后缀翻转次数](../../problems/minimum-suffix-flips) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1526 | [形成目标数组的子数组最少增加次数](../../problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1520 | [最多的不重叠子字符串](../../problems/maximum-number-of-non-overlapping-substrings) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1509 | [三次操作后最大值与最小值的最小差](../../problems/minimum-difference-between-largest-and-smallest-value-in-three-moves) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1505 | [最多 K 次交换相邻数位后得到的最小整数](../../problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits) | [[贪心](../greedy/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1488 | [避免洪水泛滥](../../problems/avoid-flood-in-the-city) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1481 | [不同整数的最少数目](../../problems/least-number-of-unique-integers-after-k-removals) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1465 | [切割后面积最大的蛋糕](../../problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1433 | [检查一个字符串是否可以打破另一个字符串](../../problems/check-if-a-string-can-break-another-string) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1432 | [改变一个整数能得到的最大差值](../../problems/max-difference-you-can-get-from-changing-an-integer) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1414 | [和为 K 的最少斐波那契数字数目](../../problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k) | [[贪心](../greedy/README.md)]  | Medium |
-| 1405 | [最长快乐字符串](../../problems/longest-happy-string) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1403 | [非递增顺序的最小子序列](../../problems/minimum-subsequence-in-non-increasing-order) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1402 | [做菜顺序](../../problems/reducing-dishes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1400 | [构造 K 个回文字符串](../../problems/construct-k-palindrome-strings) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1388 | [3n 块披萨](../../problems/pizza-with-3n-slices) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1386 | [安排电影院座位](../../problems/cinema-seat-allocation) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1383 | [最大的团队表现值](../../problems/maximum-performance-of-a-team) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1382 | [将二叉搜索树变平衡](../../problems/balance-a-binary-search-tree) | [[贪心](../greedy/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1363 | [形成三的最大倍数](../../problems/largest-multiple-of-three) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1353 | [最多可以参加的会议数目](../../problems/maximum-number-of-events-that-can-be-attended) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1338 | [数组大小减半](../../problems/reduce-array-size-to-the-half) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1330 | [翻转子数组得到最大的数组值](../../problems/reverse-subarray-to-maximize-array-value) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1328 | [破坏回文串](../../problems/break-a-palindrome) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1326 | [灌溉花园的最少水龙头数目](../../problems/minimum-number-of-taps-to-open-to-water-a-garden) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1323 | [6 和 9 组成的最大数字](../../problems/maximum-69-number) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1296 | [划分数组为连续数字的集合](../../problems/divide-array-in-sets-of-k-consecutive-numbers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1262 | [可被三整除的最大和](../../problems/greatest-sum-divisible-by-three) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1253 | [重构 2 行二进制矩阵](../../problems/reconstruct-a-2-row-binary-matrix) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1247 | [交换字符使得字符串相同](../../problems/minimum-swaps-to-make-strings-equal) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1221 | [分割平衡字符串](../../problems/split-a-string-in-balanced-strings) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1217 | [玩筹码](../../problems/minimum-cost-to-move-chips-to-the-same-position) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1199 | [建造街区的最短时间](../../problems/minimum-time-to-build-blocks) 🔒 | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1196 | [最多可以买到的苹果数量](../../problems/how-many-apples-can-you-put-into-the-basket) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1183 | [矩阵中 1 的最大数量](../../problems/maximum-number-of-ones) 🔒 | [[贪心](../greedy/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1167 | [连接棒材的最低费用](../../problems/minimum-cost-to-connect-sticks) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1147 | [段式回文](../../problems/longest-chunked-palindrome-decomposition) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1144 | [递减元素使数组呈锯齿状](../../problems/decrease-elements-to-make-array-zigzag) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1130 | [叶值的最小代价生成树](../../problems/minimum-cost-tree-from-leaf-values) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1121 | [将数组分成几个递增序列](../../problems/divide-array-into-increasing-sequences) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1090 | [受标签影响的最大值](../../problems/largest-values-from-labels) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1081 | [不同字符的最小子序列](../../problems/smallest-subsequence-of-distinct-characters) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1058 | [最小化舍入误差以满足目标](../../problems/minimize-rounding-error-to-meet-target) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1057 | [校园自行车分配](../../problems/campus-bikes) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1055 | [形成字符串的最短路径](../../problems/shortest-way-to-form-string) 🔒 | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1054 | [距离相等的条形码](../../problems/distant-barcodes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1053 | [交换一次的先前排列](../../problems/previous-permutation-with-one-swap) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1029 | [两地调度](../../problems/two-city-scheduling) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1024 | [视频拼接](../../problems/video-stitching) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1013 | [将数组分成和相等的三个部分](../../problems/partition-array-into-three-parts-with-equal-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 1011 | [在 D 天内送达包裹的能力](../../problems/capacity-to-ship-packages-within-d-days) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1007 | [行相等的最少多米诺旋转](../../problems/minimum-domino-rotations-for-equal-row) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1005 | [K 次取反后最大化的数组和](../../problems/maximize-sum-of-array-after-k-negations) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 991 | [坏了的计算器](../../problems/broken-calculator) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 984 | [不含 AAA 或 BBB 的字符串](../../problems/string-without-aaa-or-bbb) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 976 | [三角形的最大周长](../../problems/largest-perimeter-triangle) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 969 | [煎饼排序](../../problems/pancake-sorting) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 955 | [删列造序 II](../../problems/delete-columns-to-make-sorted-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 954 | [二倍数对数组](../../problems/array-of-doubled-pairs) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 948 | [令牌放置](../../problems/bag-of-tokens) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 945 | [使数组唯一的最小增量](../../problems/minimum-increment-to-make-array-unique) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 942 | [增减字符串匹配](../../problems/di-string-match) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 936 | [戳印序列](../../problems/stamping-the-sequence) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 921 | [使括号有效的最少添加](../../problems/minimum-add-to-make-parentheses-valid) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 910 | [最小差值 II](../../problems/smallest-range-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 881 | [救生艇](../../problems/boats-to-save-people) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 871 | [最低加油次数](../../problems/minimum-number-of-refueling-stops) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 870 | [优势洗牌](../../problems/advantage-shuffle) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 861 | [翻转矩阵后的得分](../../problems/score-after-flipping-matrix) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 860 | [柠檬水找零](../../problems/lemonade-change) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 857 | [雇佣 K 名工人的最低成本](../../problems/minimum-cost-to-hire-k-workers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 846 | [一手顺子](../../problems/hand-of-straights) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 826 | [安排工作以达到最大收益](../../problems/most-profit-assigning-work) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 807 | [保持城市天际线](../../problems/max-increase-to-keep-city-skyline) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 781 | [森林中的兔子](../../problems/rabbits-in-forest) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 769 | [最多能完成排序的块](../../problems/max-chunks-to-make-sorted) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 768 | [最多能完成排序的块 II](../../problems/max-chunks-to-make-sorted-ii) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 767 | [重构字符串](../../problems/reorganize-string) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 765 | [情侣牵手](../../problems/couples-holding-hands) | [[贪心](../greedy/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 763 | [划分字母区间](../../problems/partition-labels) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 757 | [设置交集大小至少为2](../../problems/set-intersection-size-at-least-two) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 738 | [单调递增的数字](../../problems/monotone-increasing-digits) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 714 | [买卖股票的最佳时机含手续费](../../problems/best-time-to-buy-and-sell-stock-with-transaction-fee) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 680 | [验证回文字符串 Ⅱ](../../problems/valid-palindrome-ii) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 678 | [有效的括号字符串](../../problems/valid-parenthesis-string) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 670 | [最大交换](../../problems/maximum-swap) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 659 | [分割数组为连续子序列](../../problems/split-array-into-consecutive-subsequences) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 649 | [Dota2 参议院](../../problems/dota2-senate) | [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 646 | [最长数对链](../../problems/maximum-length-of-pair-chain) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 632 | [最小区间](../../problems/smallest-range-covering-elements-from-k-lists) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 630 | [课程表 III](../../problems/course-schedule-iii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 625 | [最小因式分解](../../problems/minimum-factorization) 🔒 | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 624 | [数组列表中的最大距离](../../problems/maximum-distance-in-arrays) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 621 | [任务调度器](../../problems/task-scheduler) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 611 | [有效三角形的个数](../../problems/valid-triangle-number) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 605 | [种花问题](../../problems/can-place-flowers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Easy |
-| 581 | [最短无序连续子数组](../../problems/shortest-unsorted-continuous-subarray) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 561 | [数组拆分 I](../../problems/array-partition-i) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 555 | [分割连接字符串](../../problems/split-concatenated-strings) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 527 | [单词缩写](../../problems/word-abbreviation) 🔒 | [[贪心](../greedy/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 517 | [超级洗衣机](../../problems/super-washing-machines) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Hard |
-| 502 | [IPO](../../problems/ipo) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 484 | [寻找排列](../../problems/find-permutation) 🔒 | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 455 | [分发饼干](../../problems/assign-cookies) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 452 | [用最少数量的箭引爆气球](../../problems/minimum-number-of-arrows-to-burst-balloons) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 435 | [无重叠区间](../../problems/non-overlapping-intervals) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 420 | [强密码检验器](../../problems/strong-password-checker) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 410 | [分割数组的最大值](../../problems/split-array-largest-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 409 | [最长回文串](../../problems/longest-palindrome) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 406 | [根据身高重建队列](../../problems/queue-reconstruction-by-height) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 402 | [移掉 K 位数字](../../problems/remove-k-digits) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 397 | [整数替换](../../problems/integer-replacement) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 376 | [摆动序列](../../problems/wiggle-subsequence) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 358 | [K 距离间隔重排字符串](../../problems/rearrange-string-k-distance-apart) 🔒 | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 334 | [递增的三元子序列](../../problems/increasing-triplet-subsequence) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 330 | [按要求补齐数组](../../problems/patching-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Hard |
-| 321 | [拼接最大数](../../problems/create-maximum-number) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 316 | [去除重复字母](../../problems/remove-duplicate-letters) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 280 | [摆动排序](../../problems/wiggle-sort) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 277 | [搜寻名人](../../problems/find-the-celebrity) 🔒 | [[贪心](../greedy/README.md)] [[图](../graph/README.md)] [[双指针](../two-pointers/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 253 | [会议室 II](../../problems/meeting-rooms-ii) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 179 | [最大数](../../problems/largest-number) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 135 | [分发糖果](../../problems/candy) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Hard |
-| 134 | [加油站](../../problems/gas-station) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 122 | [买卖股票的最佳时机 II](../../problems/best-time-to-buy-and-sell-stock-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 55 | [跳跃游戏](../../problems/jump-game) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 45 | [跳跃游戏 II](../../problems/jump-game-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 44 | [通配符匹配](../../problems/wildcard-matching) | [[贪心](../greedy/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 11 | [盛最多水的容器](../../problems/container-with-most-water) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
diff --git a/tag/hash-function/README.md b/tag/hash-function/README.md
deleted file mode 100644
index 15abea6e7..000000000
--- a/tag/hash-function/README.md
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 哈希函数
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2168 | [Unique Substrings With Equal Digit Frequency](../../problems/unique-substrings-with-equal-digit-frequency) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 2156 | [查找给定哈希值的子串](../../problems/find-substring-with-given-hash-value) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1960 | [两个回文子字符串长度的最大乘积](../../problems/maximum-product-of-the-length-of-two-palindromic-substrings) | [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1948 | [删除系统中的重复文件夹](../../problems/delete-duplicate-folders-in-system) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 1923 | [最长公共子路径](../../problems/longest-common-subpath) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1698 | [字符串的不同子字符串个数](../../problems/number-of-distinct-substrings-in-a-string) 🔒 | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1554 | [只有一个不同字符的字符串](../../problems/strings-differ-by-one-character) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1461 | [检查一个字符串是否包含所有长度为 K 的二进制子串](../../problems/check-if-a-string-contains-all-binary-codes-of-size-k) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1392 | [最长快乐前缀](../../problems/longest-happy-prefix) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1316 | [不同的循环子字符串](../../problems/distinct-echo-substrings) | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1147 | [段式回文](../../problems/longest-chunked-palindrome-decomposition) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1062 | [最长重复子串](../../problems/longest-repeating-substring) 🔒 | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1044 | [最长重复子串](../../problems/longest-duplicate-substring) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 718 | [最长重复子数组](../../problems/maximum-length-of-repeated-subarray) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 711 | [不同岛屿的数量 II](../../problems/number-of-distinct-islands-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 706 | [设计哈希映射](../../problems/design-hashmap) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 705 | [设计哈希集合](../../problems/design-hashset) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 694 | [不同岛屿的数量](../../problems/number-of-distinct-islands) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Medium |
-| 572 | [另一棵树的子树](../../problems/subtree-of-another-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 535 | [TinyURL 的加密与解密](../../problems/encode-and-decode-tinyurl) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)]  | Medium |
-| 214 | [最短回文串](../../problems/shortest-palindrome) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 187 | [重复的DNA序列](../../problems/repeated-dna-sequences) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
diff --git a/tag/hash-table/README.md b/tag/hash-table/README.md
deleted file mode 100644
index d0645f16b..000000000
--- a/tag/hash-table/README.md
+++ /dev/null
@@ -1,372 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 哈希表
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2170 | [使数组变成交替数组的最少操作数](../../problems/minimum-operations-to-make-the-array-alternating) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2168 | [Unique Substrings With Equal Digit Frequency](../../problems/unique-substrings-with-equal-digit-frequency) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 2166 | [设计位集](../../problems/design-bitset) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 2154 | [将找到的值乘以 2](../../problems/keep-multiplying-found-values-by-two) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2152 | [Minimum Number of Lines to Cover Points](../../problems/minimum-number-of-lines-to-cover-points) 🔒 | [[位运算](../bit-manipulation/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 2150 | [找出数组中的所有孤独数字](../../problems/find-all-lonely-numbers-in-the-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2135 | [统计追加字母可以获得的单词数](../../problems/count-words-obtained-after-adding-a-letter) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2133 | [检查是否每一行每一列都包含全部整数](../../problems/check-if-every-row-and-column-contains-all-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 2131 | [连接两字母单词得到的最长回文串](../../problems/longest-palindrome-by-concatenating-two-letter-words) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2122 | [还原原数组](../../problems/recover-the-original-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2121 | [相同元素的间隔之和](../../problems/intervals-between-identical-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2115 | [从给定原材料中找到所有可以做出的菜](../../problems/find-all-possible-recipes-from-given-supplies) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2107 | [Number of Unique Flavors After Sharing K Candies](../../problems/number-of-unique-flavors-after-sharing-k-candies) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2103 | [环和杆](../../problems/rings-and-rods) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2099 | [找到和最大的长度为 K 的子序列](../../problems/find-subsequence-of-length-k-with-the-largest-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 2094 | [找出 3 位偶数](../../problems/finding-3-digit-even-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2085 | [统计出现过一次的公共字符串](../../problems/count-common-words-with-one-occurrence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2083 | [求以相同字母开头和结尾的子串总数](../../problems/substrings-that-begin-and-end-with-the-same-letter) 🔒 | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2080 | [区间内查询数字的频率](../../problems/range-frequency-queries) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 2068 | [检查两个字符串是否几乎相等](../../problems/check-whether-two-strings-are-almost-equivalent) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2062 | [统计字符串中的元音子字符串](../../problems/count-vowel-substrings-of-a-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2053 | [数组中第 K 个独一无二的字符串](../../problems/kth-distinct-string-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2043 | [简易银行系统](../../problems/simple-bank-system) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2034 | [股票价格波动](../../problems/stock-price-fluctuation) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2032 | [至少在两个数组中出现的值](../../problems/two-out-of-three) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 2025 | [分割数组的最多方案数](../../problems/maximum-number-of-ways-to-partition-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 2013 | [检测正方形](../../problems/detect-squares) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2007 | [从双倍数组中还原原数组](../../problems/find-original-array-from-doubled-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2006 | [差的绝对值为 K 的数对数目](../../problems/count-number-of-pairs-with-absolute-difference-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2001 | [可互换矩形的组数](../../problems/number-of-pairs-of-interchangeable-rectangles) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1993 | [树上的操作](../../problems/operations-on-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1948 | [删除系统中的重复文件夹](../../problems/delete-duplicate-folders-in-system) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 1941 | [检查是否所有字符出现次数相同](../../problems/check-if-all-characters-have-equal-number-of-occurrences) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1940 | [排序数组之间的最长公共子序列](../../problems/longest-common-subsequence-between-sorted-arrays) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1935 | [可以输入的最大单词数](../../problems/maximum-number-of-words-you-can-type) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1932 | [合并多棵二叉搜索树](../../problems/merge-bsts-to-create-single-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1930 | [长度为 3 的不同回文子序列](../../problems/unique-length-3-palindromic-subsequences) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1915 | [最美子字符串的数目](../../problems/number-of-wonderful-substrings) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1912 | [设计电影租借系统](../../problems/design-movie-rental-system) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1906 | [查询差绝对值的最小值](../../problems/minimum-absolute-difference-queries) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1897 | [重新分配字符使所有字符串都相等](../../problems/redistribute-characters-to-make-all-strings-equal) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1893 | [检查是否区域内所有整数都被覆盖](../../problems/check-if-all-the-integers-in-a-range-are-covered) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1876 | [长度为三且各字符不同的子字符串](../../problems/substrings-of-size-three-with-distinct-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1865 | [找出和为指定值的下标对](../../problems/finding-pairs-with-a-certain-sum) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1857 | [有向图中最大颜色值](../../problems/largest-color-value-in-a-directed-graph) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)] [[计数](../counting/README.md)]  | Hard |
-| 1852 | [每个子数组的数字种类数](../../problems/distinct-numbers-in-each-subarray) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1836 | [从未排序的链表中移除重复元素](../../problems/remove-duplicates-from-an-unsorted-linked-list) 🔒 | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 1832 | [判断句子是否为全字母句](../../problems/check-if-the-sentence-is-pangram) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1817 | [查找用户活跃分钟数](../../problems/finding-the-users-active-minutes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1814 | [统计一个数组中好对子的数目](../../problems/count-nice-pairs-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1807 | [替换字符串中的括号内容](../../problems/evaluate-the-bracket-pairs-of-a-string) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1805 | [字符串中不同整数的数目](../../problems/number-of-different-integers-in-a-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1804 | [实现 Trie （前缀树） II](../../problems/implement-trie-ii-prefix-tree) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1797 | [设计一个验证系统](../../problems/design-authentication-manager) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1796 | [字符串中第二大的数字](../../problems/second-largest-digit-in-a-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1794 | [统计距离最小的子串对个数](../../problems/count-pairs-of-equal-substrings-with-minimum-difference) 🔒 | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1790 | [仅执行一次字符串交换能否使两个字符串相等](../../problems/check-if-one-string-swap-can-make-strings-equal) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1781 | [所有子字符串美丽值之和](../../problems/sum-of-beauty-of-all-substrings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1775 | [通过最少操作次数使数组的和相等](../../problems/equal-sum-arrays-with-minimum-number-of-operations) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1772 | [按受欢迎程度排列功能](../../problems/sort-features-by-popularity) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1763 | [最长的美好子字符串](../../problems/longest-nice-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1756 | [设计最近使用（MRU）队列](../../problems/design-most-recently-used-queue) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1748 | [唯一元素的和](../../problems/sum-of-unique-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1743 | [从相邻元素对还原数组](../../problems/restore-the-array-from-adjacent-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1742 | [盒子中小球的最大数量](../../problems/maximum-number-of-balls-in-a-box) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1740 | [找到二叉树中的距离](../../problems/find-distance-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1737 | [满足三条件之一需改变的最少字符数](../../problems/change-minimum-characters-to-satisfy-one-of-three-conditions) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1726 | [同积元组](../../problems/tuple-with-same-product) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1713 | [得到子序列的最少操作次数](../../problems/minimum-operations-to-make-a-subsequence) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1711 | [大餐计数](../../problems/count-good-meals) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1695 | [删除子数组的最大得分](../../problems/maximum-erasure-value) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1684 | [统计一致字符串的数目](../../problems/count-the-number-of-consistent-strings) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1679 | [K 和数对的最大数目](../../problems/max-number-of-k-sum-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1674 | [使数组互补的最少操作次数](../../problems/minimum-moves-to-make-array-complementary) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1660 | [纠正二叉树](../../problems/correct-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1658 | [将 x 减到 0 的最小操作数](../../problems/minimum-operations-to-reduce-x-to-zero) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1657 | [确定两个字符串是否接近](../../problems/determine-if-two-strings-are-close) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1656 | [设计有序流](../../problems/design-an-ordered-stream) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 1650 | [二叉树的最近公共祖先 III](../../problems/lowest-common-ancestor-of-a-binary-tree-iii) 🔒 | [[树](../tree/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1640 | [能否连接形成数组](../../problems/check-array-formation-through-concatenation) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 1638 | [统计只差一个字符的子串数目](../../problems/count-substrings-that-differ-by-one-character) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1636 | [按照频率将数组升序排序](../../problems/sort-array-by-increasing-frequency) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1624 | [两个相同字符之间的最长子字符串](../../problems/largest-substring-between-two-equal-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1604 | [警告一小时内使用相同员工卡大于等于三次的人](../../problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1600 | [皇位继承顺序](../../problems/throne-inheritance) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1593 | [拆分字符串使唯一子字符串的数目最大](../../problems/split-a-string-into-the-max-number-of-unique-substrings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1590 | [使数组和能被 P 整除](../../problems/make-sum-divisible-by-p) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1577 | [数的平方等于两数乘积的方法数](../../problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1570 | [两个稀疏向量的点积](../../problems/dot-product-of-two-sparse-vectors) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1554 | [只有一个不同字符的字符串](../../problems/strings-differ-by-one-character) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1546 | [和为目标值且不重叠的非空子数组的最大数目](../../problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1542 | [找出最长的超赞子字符串](../../problems/find-longest-awesome-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1540 | [K 次操作转变字符串](../../problems/can-convert-string-in-k-moves) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1512 | [好数对的数目](../../problems/number-of-good-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1506 | [找到 N 叉树的根节点](../../problems/find-root-of-n-ary-tree) 🔒 | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1500 | [设计文件分享系统](../../problems/design-a-file-sharing-system) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1497 | [检查数组对是否可以被 k 整除](../../problems/check-if-array-pairs-are-divisible-by-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1496 | [判断路径是否相交](../../problems/path-crossing) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1490 | [克隆 N 叉树](../../problems/clone-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1488 | [避免洪水泛滥](../../problems/avoid-flood-in-the-city) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1487 | [保证文件名唯一](../../problems/making-file-names-unique) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1485 | [克隆含随机指针的二叉树](../../problems/clone-binary-tree-with-random-pointer) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1481 | [不同整数的最少数目](../../problems/least-number-of-unique-integers-after-k-removals) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1477 | [找两个和为目标值且不重叠的子数组](../../problems/find-two-non-overlapping-sub-arrays-each-with-target-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1461 | [检查一个字符串是否包含所有长度为 K 的二进制子串](../../problems/check-if-a-string-contains-all-binary-codes-of-size-k) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1460 | [通过翻转子数组使两个数组相等](../../problems/make-two-arrays-equal-by-reversing-sub-arrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1452 | [收藏清单](../../problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1443 | [收集树上所有苹果的最少时间](../../problems/minimum-time-to-collect-all-apples-in-a-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1442 | [形成两个异或相等数组的三元组数目](../../problems/count-triplets-that-can-form-two-arrays-of-equal-xor) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1436 | [旅行终点站](../../problems/destination-city) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1429 | [第一个唯一数字](../../problems/first-unique-number) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1426 | [数元素](../../problems/counting-elements) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 1418 | [点菜展示表](../../problems/display-table-of-food-orders-in-a-restaurant) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1410 | [HTML 实体解析器](../../problems/html-entity-parser) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1400 | [构造 K 个回文字符串](../../problems/construct-k-palindrome-strings) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1399 | [统计最大组的数目](../../problems/count-largest-group) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1396 | [设计地铁系统](../../problems/design-underground-system) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1394 | [找出数组中的幸运数](../../problems/find-lucky-integer-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1386 | [安排电影院座位](../../problems/cinema-seat-allocation) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1371 | [每个元音包含偶数次的最长子字符串](../../problems/find-the-longest-substring-containing-vowels-in-even-counts) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1370 | [上升下降字符串](../../problems/increasing-decreasing-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1366 | [通过投票对团队排名](../../problems/rank-teams-by-votes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1365 | [有多少小于当前数字的数字](../../problems/how-many-numbers-are-smaller-than-the-current-number) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1358 | [包含所有三种字符的子字符串数目](../../problems/number-of-substrings-containing-all-three-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1357 | [每隔 n 个顾客打折](../../problems/apply-discount-every-n-orders) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1348 | [推文计数](../../problems/tweet-counts-per-frequency) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1347 | [制造字母异位词的最小步骤数](../../problems/minimum-number-of-steps-to-make-two-strings-anagram) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1346 | [检查整数及其两倍数是否存在](../../problems/check-if-n-and-its-double-exist) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1345 | [跳跃游戏 IV](../../problems/jump-game-iv) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1338 | [数组大小减半](../../problems/reduce-array-size-to-the-half) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1331 | [数组序号转换](../../problems/rank-transform-of-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1325 | [删除给定值的叶子节点](../../problems/delete-leaves-with-a-given-value) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1311 | [获取你好友已观看的视频](../../problems/get-watched-videos-by-your-friends) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1297 | [子串的最大出现次数](../../problems/maximum-number-of-occurrences-of-a-substring) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1296 | [划分数组为连续数字的集合](../../problems/divide-array-in-sets-of-k-consecutive-numbers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1282 | [用户分组](../../problems/group-the-people-given-the-group-size-they-belong-to) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1275 | [找出井字棋的获胜者](../../problems/find-winner-on-a-tic-tac-toe-game) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1258 | [近义词句子](../../problems/synonymous-sentences) 🔒 | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1257 | [最小公共区域](../../problems/smallest-common-region) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1248 | [统计「优美子数组」](../../problems/count-number-of-nice-subarrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1244 | [力扣排行榜](../../problems/design-a-leaderboard) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1224 | [最大相等频率](../../problems/maximum-equal-frequency) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1218 | [最长定差子序列](../../problems/longest-arithmetic-subsequence-of-given-difference) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1213 | [三个有序数组的交集](../../problems/intersection-of-three-sorted-arrays) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1207 | [独一无二的出现次数](../../problems/unique-number-of-occurrences) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 1202 | [交换字符串中的元素](../../problems/smallest-string-with-swaps) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1198 | [找出所有行中最小公共元素](../../problems/find-smallest-common-element-in-all-rows) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1189 | [“气球” 的最大数量](../../problems/maximum-number-of-balloons) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1181 | [前后拼接](../../problems/before-and-after-puzzle) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1178 | [猜字谜](../../problems/number-of-valid-words-for-each-puzzle) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1177 | [构建回文串检测](../../problems/can-make-palindrome-from-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1172 | [餐盘栈](../../problems/dinner-plate-stacks) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1171 | [从链表中删去总和值为零的连续节点](../../problems/remove-zero-sum-consecutive-nodes-from-linked-list) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 1170 | [比较字符串最小字母出现频次](../../problems/compare-strings-by-frequency-of-the-smallest-character) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1169 | [查询无效交易](../../problems/invalid-transactions) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1166 | [设计文件系统](../../problems/design-file-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1165 | [单行键盘](../../problems/single-row-keyboard) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1160 | [拼写单词](../../problems/find-words-that-can-be-formed-by-characters) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1153 | [字符串转化](../../problems/string-transforms-into-another-string) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1152 | [用户网站访问行为分析](../../problems/analyze-user-website-visit-pattern) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1146 | [快照数组](../../problems/snapshot-array) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1138 | [字母板上的路径](../../problems/alphabet-board-path) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1133 | [最大唯一数](../../problems/largest-unique-number) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1128 | [等价多米诺骨牌对的数量](../../problems/number-of-equivalent-domino-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1124 | [表现良好的最长时间段](../../problems/longest-well-performing-interval) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1123 | [最深叶节点的最近公共祖先](../../problems/lowest-common-ancestor-of-deepest-leaves) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1122 | [数组的相对排序](../../problems/relative-sort-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1100 | [长度为 K 的无重复字符子串](../../problems/find-k-length-substrings-with-no-repeated-characters) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1090 | [受标签影响的最大值](../../problems/largest-values-from-labels) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1086 | [前五科的均分](../../problems/high-five) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1074 | [元素和为目标值的子矩阵数量](../../problems/number-of-submatrices-that-sum-to-target) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1072 | [按列翻转得到最大值等行数](../../problems/flip-columns-for-maximum-number-of-equal-rows) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1054 | [距离相等的条形码](../../problems/distant-barcodes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1048 | [最长字符串链](../../problems/longest-string-chain) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1036 | [逃离大迷宫](../../problems/escape-a-large-maze) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 1027 | [最长等差数列](../../problems/longest-arithmetic-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1015 | [可被 K 整除的最小整数](../../problems/smallest-integer-divisible-by-k) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1010 | [总持续时间可被 60 整除的歌曲](../../problems/pairs-of-songs-with-total-durations-divisible-by-60) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1002 | [查找共用字符](../../problems/find-common-characters) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1001 | [网格照明](../../problems/grid-illumination) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 997 | [找到小镇的法官](../../problems/find-the-town-judge) | [[图](../graph/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 992 | [K 个不同整数的子数组](../../problems/subarrays-with-k-different-integers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 987 | [二叉树的垂序遍历](../../problems/vertical-order-traversal-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 982 | [按位与为零的三元组](../../problems/triples-with-bitwise-and-equal-to-zero) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 981 | [基于时间的键值存储](../../problems/time-based-key-value-store) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 974 | [和可被 K 整除的子数组](../../problems/subarray-sums-divisible-by-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 970 | [强整数](../../problems/powerful-integers) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 966 | [元音拼写检查器](../../problems/vowel-spellchecker) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 961 | [在长度 2N 的数组中找出重复 N 次的元素](../../problems/n-repeated-element-in-size-2n-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 957 | [N 天后的牢房](../../problems/prison-cells-after-n-days) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 954 | [二倍数对数组](../../problems/array-of-doubled-pairs) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 953 | [验证外星语词典](../../problems/verifying-an-alien-dictionary) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 939 | [最小面积矩形](../../problems/minimum-area-rectangle) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 930 | [和相同的二元子数组](../../problems/binary-subarrays-with-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 929 | [独特的电子邮件地址](../../problems/unique-email-addresses) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 923 | [三数之和的多种可能](../../problems/3sum-with-multiplicity) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 916 | [单词子集](../../problems/word-subsets) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 914 | [卡牌分组](../../problems/x-of-a-kind-in-a-deck-of-cards) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Easy |
-| 911 | [在线选举](../../problems/online-election) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 904 | [水果成篮](../../problems/fruit-into-baskets) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 895 | [最大频率栈](../../problems/maximum-frequency-stack) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 893 | [特殊等价字符串组](../../problems/groups-of-special-equivalent-strings) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 890 | [查找和替换模式](../../problems/find-and-replace-pattern) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 889 | [根据前序和后序遍历构造二叉树](../../problems/construct-binary-tree-from-preorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 888 | [公平的糖果交换](../../problems/fair-candy-swap) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 884 | [两句话中的不常见单词](../../problems/uncommon-words-from-two-sentences) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 873 | [最长的斐波那契子序列的长度](../../problems/length-of-longest-fibonacci-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 865 | [具有所有最深节点的最小子树](../../problems/smallest-subtree-with-all-the-deepest-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 859 | [亲密字符串](../../problems/buddy-strings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 846 | [一手顺子](../../problems/hand-of-straights) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 823 | [带因子的二叉树](../../problems/binary-trees-with-factors) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 822 | [翻转卡片游戏](../../problems/card-flipping-game) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 820 | [单词的压缩编码](../../problems/short-encoding-of-words) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 819 | [最常见的单词](../../problems/most-common-word) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 817 | [链表组件](../../problems/linked-list-components) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 815 | [公交路线](../../problems/bus-routes) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 811 | [子域名访问计数](../../problems/subdomain-visit-count) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 804 | [唯一摩尔斯密码词](../../problems/unique-morse-code-words) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 792 | [匹配子序列的单词数](../../problems/number-of-matching-subsequences) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 791 | [自定义字符串排序](../../problems/custom-sort-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 781 | [森林中的兔子](../../problems/rabbits-in-forest) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 771 | [宝石与石头](../../problems/jewels-and-stones) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 770 | [基本计算器 IV](../../problems/basic-calculator-iv) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 767 | [重构字符串](../../problems/reorganize-string) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 763 | [划分字母区间](../../problems/partition-labels) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 760 | [找出变位映射](../../problems/find-anagram-mappings) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 758 | [字符串中的加粗单词](../../problems/bold-words-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 752 | [打开转盘锁](../../problems/open-the-lock) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 748 | [最短补全词](../../problems/shortest-completing-word) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 740 | [删除并获得点数](../../problems/delete-and-earn) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 737 | [句子相似性 II](../../problems/sentence-similarity-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 736 | [Lisp 语法解析](../../problems/parse-lisp-expression) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 734 | [句子相似性](../../problems/sentence-similarity) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 726 | [原子的数量](../../problems/number-of-atoms) | [[栈](../stack/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 720 | [词典中最长的单词](../../problems/longest-word-in-dictionary) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 711 | [不同岛屿的数量 II](../../problems/number-of-distinct-islands-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 710 | [黑名单中的随机数](../../problems/random-pick-with-blacklist) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 706 | [设计哈希映射](../../problems/design-hashmap) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 705 | [设计哈希集合](../../problems/design-hashset) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 697 | [数组的度](../../problems/degree-of-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 694 | [不同岛屿的数量](../../problems/number-of-distinct-islands) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Medium |
-| 692 | [前K个高频单词](../../problems/top-k-frequent-words) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 690 | [员工的重要性](../../problems/employee-importance) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 677 | [键值映射](../../problems/map-sum-pairs) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 676 | [实现一个魔法字典](../../problems/implement-magic-dictionary) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 659 | [分割数组为连续子序列](../../problems/split-array-into-consecutive-subsequences) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 653 | [两数之和 IV - 输入 BST](../../problems/two-sum-iv-input-is-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 648 | [单词替换](../../problems/replace-words) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 645 | [错误的集合](../../problems/set-mismatch) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 635 | [设计日志存储系统](../../problems/design-log-storage-system) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 632 | [最小区间](../../problems/smallest-range-covering-elements-from-k-lists) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 621 | [任务调度器](../../problems/task-scheduler) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 616 | [给字符串添加加粗标签](../../problems/add-bold-tag-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 609 | [在系统中查找重复文件](../../problems/find-duplicate-file-in-system) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 604 | [迭代压缩字符串](../../problems/design-compressed-string-iterator) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[迭代器](../iterator/README.md)]  | Easy |
-| 599 | [两个列表的最小索引总和](../../problems/minimum-index-sum-of-two-lists) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 594 | [最长和谐子序列](../../problems/longest-harmonious-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 588 | [设计内存文件系统](../../problems/design-in-memory-file-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 582 | [杀掉进程](../../problems/kill-process) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 575 | [分糖果](../../problems/distribute-candies) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 567 | [字符串的排列](../../problems/permutation-in-string) | [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 560 | [和为 K 的子数组](../../problems/subarray-sum-equals-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 554 | [砖墙](../../problems/brick-wall) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 535 | [TinyURL 的加密与解密](../../problems/encode-and-decode-tinyurl) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)]  | Medium |
-| 533 | [孤独像素 II](../../problems/lonely-pixel-ii) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 532 | [数组中的 k-diff 数对](../../problems/k-diff-pairs-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 531 | [孤独像素 I](../../problems/lonely-pixel-i) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 525 | [连续数组](../../problems/contiguous-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 523 | [连续的子数组和](../../problems/continuous-subarray-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 522 | [最长特殊序列 II](../../problems/longest-uncommon-subsequence-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 519 | [随机翻转矩阵](../../problems/random-flip-matrix) | [[水塘抽样](../reservoir-sampling/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 508 | [出现次数最多的子树元素和](../../problems/most-frequent-subtree-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 500 | [键盘行](../../problems/keyboard-row) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 496 | [下一个更大元素 I](../../problems/next-greater-element-i) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Easy |
-| 491 | [递增子序列](../../problems/increasing-subsequences) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 480 | [滑动窗口中位数](../../problems/sliding-window-median) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 460 | [LFU 缓存](../../problems/lfu-cache) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Hard |
-| 457 | [环形数组是否存在循环](../../problems/circular-array-loop) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 454 | [四数相加 II](../../problems/4sum-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 451 | [根据字符出现频率排序](../../problems/sort-characters-by-frequency) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 448 | [找到所有数组中消失的数字](../../problems/find-all-numbers-disappeared-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 447 | [回旋镖的数量](../../problems/number-of-boomerangs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 442 | [数组中重复的数据](../../problems/find-all-duplicates-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 438 | [找到字符串中所有字母异位词](../../problems/find-all-anagrams-in-a-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 433 | [最小基因变化](../../problems/minimum-genetic-mutation) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 432 | [全 O(1) 的数据结构](../../problems/all-oone-data-structure) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Hard |
-| 424 | [替换后的最长重复字符](../../problems/longest-repeating-character-replacement) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 423 | [从英文中重建数字](../../problems/reconstruct-original-digits-from-english) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 421 | [数组中两个数的最大异或值](../../problems/maximum-xor-of-two-numbers-in-an-array) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 409 | [最长回文串](../../problems/longest-palindrome) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 398 | [随机数索引](../../problems/random-pick-index) | [[水塘抽样](../reservoir-sampling/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 395 | [至少有 K 个重复字符的最长子串](../../problems/longest-substring-with-at-least-k-repeating-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 389 | [找不同](../../problems/find-the-difference) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 387 | [字符串中的第一个唯一字符](../../problems/first-unique-character-in-a-string) | [[队列](../queue/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 383 | [赎金信](../../problems/ransom-note) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 381 | [O(1) 时间插入、删除和获取随机元素 - 允许重复](../../problems/insert-delete-getrandom-o1-duplicates-allowed) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 380 | [O(1) 时间插入、删除和获取随机元素](../../problems/insert-delete-getrandom-o1) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 379 | [电话目录管理系统](../../problems/design-phone-directory) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 362 | [敲击计数器](../../problems/design-hit-counter) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 359 | [日志速率限制器](../../problems/logger-rate-limiter) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
-| 358 | [K 距离间隔重排字符串](../../problems/rearrange-string-k-distance-apart) 🔒 | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 356 | [直线镜像](../../problems/line-reflection) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 355 | [设计推特](../../problems/design-twitter) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 350 | [两个数组的交集 II](../../problems/intersection-of-two-arrays-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 349 | [两个数组的交集](../../problems/intersection-of-two-arrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 348 | [设计井字棋](../../problems/design-tic-tac-toe) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 347 | [前 K 个高频元素](../../problems/top-k-frequent-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 340 | [至多包含 K 个不同字符的最长子串](../../problems/longest-substring-with-at-most-k-distinct-characters) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 336 | [回文对](../../problems/palindrome-pairs) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 325 | [和等于 k 的最长子数组长度](../../problems/maximum-size-subarray-sum-equals-k) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 314 | [二叉树的垂直遍历](../../problems/binary-tree-vertical-order-traversal) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 313 | [超级丑数](../../problems/super-ugly-number) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 311 | [稀疏矩阵的乘法](../../problems/sparse-matrix-multiplication) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 299 | [猜数字游戏](../../problems/bulls-and-cows) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 291 | [单词规律 II](../../problems/word-pattern-ii) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 290 | [单词规律](../../problems/word-pattern) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 288 | [单词的唯一缩写](../../problems/unique-word-abbreviation) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 268 | [丢失的数字](../../problems/missing-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 267 | [回文排列 II](../../problems/palindrome-permutation-ii) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 266 | [回文排列](../../problems/palindrome-permutation) 🔒 | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 264 | [丑数 II](../../problems/ugly-number-ii) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 249 | [移位字符串分组](../../problems/group-shifted-strings) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 246 | [中心对称数](../../problems/strobogrammatic-number) 🔒 | [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 244 | [最短单词距离 II](../../problems/shortest-word-distance-ii) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 242 | [有效的字母异位词](../../problems/valid-anagram) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 229 | [求众数 II](../../problems/majority-element-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 219 | [存在重复元素 II](../../problems/contains-duplicate-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 217 | [存在重复元素](../../problems/contains-duplicate) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 208 | [实现 Trie (前缀树)](../../problems/implement-trie-prefix-tree) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 205 | [同构字符串](../../problems/isomorphic-strings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 202 | [快乐数](../../problems/happy-number) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 187 | [重复的DNA序列](../../problems/repeated-dna-sequences) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 170 | [两数之和 III - 数据结构设计](../../problems/two-sum-iii-data-structure-design) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 169 | [多数元素](../../problems/majority-element) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 166 | [分数到小数](../../problems/fraction-to-recurring-decimal) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 160 | [相交链表](../../problems/intersection-of-two-linked-lists) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 159 | [至多包含两个不同字符的最长子串](../../problems/longest-substring-with-at-most-two-distinct-characters) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 149 | [直线上最多的点数](../../problems/max-points-on-a-line) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Hard |
-| 146 | [LRU 缓存](../../problems/lru-cache) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 142 | [环形链表 II](../../problems/linked-list-cycle-ii) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 141 | [环形链表](../../problems/linked-list-cycle) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 140 | [单词拆分 II](../../problems/word-break-ii) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 139 | [单词拆分](../../problems/word-break) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 138 | [复制带随机指针的链表](../../problems/copy-list-with-random-pointer) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 133 | [克隆图](../../problems/clone-graph) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 128 | [最长连续序列](../../problems/longest-consecutive-sequence) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 127 | [单词接龙](../../problems/word-ladder) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 126 | [单词接龙 II](../../problems/word-ladder-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 106 | [从中序与后序遍历序列构造二叉树](../../problems/construct-binary-tree-from-inorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 105 | [从前序与中序遍历序列构造二叉树](../../problems/construct-binary-tree-from-preorder-and-inorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 76 | [最小覆盖子串](../../problems/minimum-window-substring) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 73 | [矩阵置零](../../problems/set-matrix-zeroes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 49 | [字母异位词分组](../../problems/group-anagrams) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 41 | [缺失的第一个正数](../../problems/first-missing-positive) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Hard |
-| 36 | [有效的数独](../../problems/valid-sudoku) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 30 | [串联所有单词的子串](../../problems/substring-with-concatenation-of-all-words) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 17 | [电话号码的字母组合](../../problems/letter-combinations-of-a-phone-number) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 13 | [罗马数字转整数](../../problems/roman-to-integer) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 12 | [整数转罗马数字](../../problems/integer-to-roman) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 3 | [无重复字符的最长子串](../../problems/longest-substring-without-repeating-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1 | [两数之和](../../problems/two-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Easy |
diff --git a/tag/heap-priority-queue/README.md b/tag/heap-priority-queue/README.md
deleted file mode 100644
index 04cdd71aa..000000000
--- a/tag/heap-priority-queue/README.md
+++ /dev/null
@@ -1,113 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 堆（优先队列）
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2163 | [删除元素后和的最小差值](../../problems/minimum-difference-in-sums-after-removal-of-elements) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 2146 | [价格范围内最高排名的 K 样物品](../../problems/k-highest-ranked-items-within-a-price-range) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2102 | [序列顺序查询](../../problems/sequentially-ordinal-rank-tracker) | [[设计](../design/README.md)] [[数据流](../data-stream/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 2099 | [找到和最大的长度为 K 的子序列](../../problems/find-subsequence-of-length-k-with-the-largest-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 2054 | [两个最好的不重叠活动](../../problems/two-best-non-overlapping-events) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2034 | [股票价格波动](../../problems/stock-price-fluctuation) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2015 | [Average Height of Buildings in Each Segment](../../problems/average-height-of-buildings-in-each-segment) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1985 | [找出数组中的第 K 大整数](../../problems/find-the-kth-largest-integer-in-the-array) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1962 | [移除石子使总数最小](../../problems/remove-stones-to-minimize-the-total) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1942 | [最小未被占据椅子的编号](../../problems/the-number-of-the-smallest-unoccupied-chair) | [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1912 | [设计电影租借系统](../../problems/design-movie-rental-system) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1882 | [使用服务器处理任务](../../problems/process-tasks-using-servers) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1878 | [矩阵中最大的三个菱形和](../../problems/get-biggest-three-rhombus-sums-in-a-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1851 | [包含每个查询的最小区间](../../problems/minimum-interval-to-include-each-query) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1845 | [座位预约管理系统](../../problems/seat-reservation-manager) | [[设计](../design/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1834 | [单线程 CPU](../../problems/single-threaded-cpu) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1825 | [求出 MK 平均值](../../problems/finding-mk-average) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1810 | [隐藏网格下的最小消耗路径](../../problems/minimum-path-cost-in-a-hidden-grid) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[交互](../interactive/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1801 | [积压订单中的订单总数](../../problems/number-of-orders-in-the-backlog) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1792 | [最大平均通过率](../../problems/maximum-average-pass-ratio) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1786 | [从第一个节点出发到最后一个节点的受限路径数](../../problems/number-of-restricted-paths-from-first-to-last-node) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1776 | [车队 II](../../problems/car-fleet-ii) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[单调栈](../monotonic-stack/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1753 | [移除石子的最大得分](../../problems/maximum-score-from-removing-stones) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1738 | [找出第 K 大的异或坐标值](../../problems/find-kth-largest-xor-coordinate-value) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[快速选择](../quickselect/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1705 | [吃苹果的最大数目](../../problems/maximum-number-of-eaten-apples) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1696 | [跳跃游戏 VI](../../problems/jump-game-vi) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1687 | [从仓库到码头运输箱子](../../problems/delivering-boxes-from-storage-to-ports) | [[线段树](../segment-tree/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1686 | [石子游戏 VI](../../problems/stone-game-vi) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1675 | [数组的最小偏移量](../../problems/minimize-deviation-in-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1648 | [销售价值减少的颜色球](../../problems/sell-diminishing-valued-colored-balls) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1642 | [可以到达的最远建筑](../../problems/furthest-building-you-can-reach) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1631 | [最小体力消耗路径](../../problems/path-with-minimum-effort) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1606 | [找到处理最多请求的服务器](../../problems/find-servers-that-handled-most-number-of-requests) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1514 | [概率最大的路径](../../problems/path-with-maximum-probability) | [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1500 | [设计文件分享系统](../../problems/design-a-file-sharing-system) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1499 | [满足不等式的最大值](../../problems/max-value-of-equation) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1488 | [避免洪水泛滥](../../problems/avoid-flood-in-the-city) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1464 | [数组中两元素的最大乘积](../../problems/maximum-product-of-two-elements-in-an-array) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 1439 | [有序矩阵中的第 k 个最小数组和](../../problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1438 | [绝对差不超过限制的最长连续子数组](../../problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1425 | [带限制的子序列和](../../problems/constrained-subsequence-sum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1424 | [对角线遍历 II](../../problems/diagonal-traverse-ii) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1405 | [最长快乐字符串](../../problems/longest-happy-string) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1388 | [3n 块披萨](../../problems/pizza-with-3n-slices) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1383 | [最大的团队表现值](../../problems/maximum-performance-of-a-team) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1368 | [使网格图至少有一条有效路径的最小代价](../../problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1354 | [多次求和构造目标数组](../../problems/construct-target-array-with-multiple-sums) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1353 | [最多可以参加的会议数目](../../problems/maximum-number-of-events-that-can-be-attended) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1338 | [数组大小减半](../../problems/reduce-array-size-to-the-half) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1337 | [矩阵中战斗力最弱的 K 行](../../problems/the-k-weakest-rows-in-a-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 1263 | [推箱子](../../problems/minimum-moves-to-move-a-box-to-their-target-location) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1199 | [建造街区的最短时间](../../problems/minimum-time-to-build-blocks) 🔒 | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1183 | [矩阵中 1 的最大数量](../../problems/maximum-number-of-ones) 🔒 | [[贪心](../greedy/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1172 | [餐盘栈](../../problems/dinner-plate-stacks) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1167 | [连接棒材的最低费用](../../problems/minimum-cost-to-connect-sticks) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1135 | [最低成本联通所有城市](../../problems/connecting-cities-with-minimum-cost) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1102 | [得分最高的路径](../../problems/path-with-maximum-minimum-value) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1094 | [拼车](../../problems/car-pooling) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1054 | [距离相等的条形码](../../problems/distant-barcodes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1046 | [最后一块石头的重量](../../problems/last-stone-weight) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 973 | [最接近原点的 K 个点](../../problems/k-closest-points-to-origin) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 912 | [排序数组](../../problems/sort-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数排序](../counting-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 882 | [细分图中的可到达结点](../../problems/reachable-nodes-in-subdivided-graph) | [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 871 | [最低加油次数](../../problems/minimum-number-of-refueling-stops) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 862 | [和至少为 K 的最短子数组](../../problems/shortest-subarray-with-sum-at-least-k) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 857 | [雇佣 K 名工人的最低成本](../../problems/minimum-cost-to-hire-k-workers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 787 | [K 站中转内最便宜的航班](../../problems/cheapest-flights-within-k-stops) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 786 | [第 K 个最小的素数分数](../../problems/k-th-smallest-prime-fraction) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 778 | [水位上升的泳池中游泳](../../problems/swim-in-rising-water) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 767 | [重构字符串](../../problems/reorganize-string) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 759 | [员工空闲时间](../../problems/employee-free-time) 🔒 | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 743 | [网络延迟时间](../../problems/network-delay-time) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 703 | [数据流中的第 K 大元素](../../problems/kth-largest-element-in-a-stream) | [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 692 | [前K个高频单词](../../problems/top-k-frequent-words) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 675 | [为高尔夫比赛砍树](../../problems/cut-off-trees-for-golf-event) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 659 | [分割数组为连续子序列](../../problems/split-array-into-consecutive-subsequences) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 658 | [找到 K 个最接近的元素](../../problems/find-k-closest-elements) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 632 | [最小区间](../../problems/smallest-range-covering-elements-from-k-lists) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 630 | [课程表 III](../../problems/course-schedule-iii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 621 | [任务调度器](../../problems/task-scheduler) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 506 | [相对名次](../../problems/relative-ranks) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 505 | [迷宫 II](../../problems/the-maze-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 502 | [IPO](../../problems/ipo) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 499 | [迷宫 III](../../problems/the-maze-iii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 480 | [滑动窗口中位数](../../problems/sliding-window-median) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 451 | [根据字符出现频率排序](../../problems/sort-characters-by-frequency) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 420 | [强密码检验器](../../problems/strong-password-checker) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 407 | [接雨水 II](../../problems/trapping-rain-water-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 378 | [有序矩阵中第 K 小的元素](../../problems/kth-smallest-element-in-a-sorted-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 373 | [查找和最小的 K 对数字](../../problems/find-k-pairs-with-smallest-sums) | [[数组](../array/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 358 | [K 距离间隔重排字符串](../../problems/rearrange-string-k-distance-apart) 🔒 | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 355 | [设计推特](../../problems/design-twitter) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 347 | [前 K 个高频元素](../../problems/top-k-frequent-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 313 | [超级丑数](../../problems/super-ugly-number) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 295 | [数据流的中位数](../../problems/find-median-from-data-stream) | [[设计](../design/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 272 | [最接近的二叉搜索树值 II](../../problems/closest-binary-search-tree-value-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 264 | [丑数 II](../../problems/ugly-number-ii) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 253 | [会议室 II](../../problems/meeting-rooms-ii) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 239 | [滑动窗口最大值](../../problems/sliding-window-maximum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 218 | [天际线问题](../../problems/the-skyline-problem) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 215 | [数组中的第K个最大元素](../../problems/kth-largest-element-in-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 23 | [合并K个升序链表](../../problems/merge-k-sorted-lists) | [[链表](../linked-list/README.md)] [[分治](../divide-and-conquer/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
diff --git a/tag/heap/README.md b/tag/heap/README.md
deleted file mode 100644
index 48c257e6f..000000000
--- a/tag/heap/README.md
+++ /dev/null
@@ -1,11 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 堆
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
diff --git a/tag/interactive/README.md b/tag/interactive/README.md
deleted file mode 100644
index 542b0fb48..000000000
--- a/tag/interactive/README.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 交互
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1810 | [隐藏网格下的最小消耗路径](../../problems/minimum-path-cost-in-a-hidden-grid) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[交互](../interactive/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1778 | [未知网格中的最短路径](../../problems/shortest-path-in-a-hidden-grid) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1618 | [找出适应屏幕的最大字号](../../problems/maximum-font-to-fit-a-sentence-in-a-screen) 🔒 | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1538 | [找出隐藏数组中出现次数最多的元素](../../problems/guess-the-majority-in-a-hidden-array) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1533 | [找到最大整数的索引](../../problems/find-the-index-of-the-large-integer) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1428 | [至少有一个 1 的最左端列](../../problems/leftmost-column-with-at-least-a-one) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1274 | [矩形内船只的数目](../../problems/number-of-ships-in-a-rectangle) 🔒 | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 1237 | [找出给定方程的正整数解](../../problems/find-positive-integer-solution-for-a-given-equation) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1236 | [网络爬虫](../../problems/web-crawler) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1095 | [山脉数组中查找目标值](../../problems/find-in-mountain-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 843 | [猜猜这个单词](../../problems/guess-the-word) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[博弈](../game-theory/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 702 | [搜索长度未知的有序数组](../../problems/search-in-a-sorted-array-of-unknown-size) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 489 | [扫地机器人](../../problems/robot-room-cleaner) 🔒 | [[回溯](../backtracking/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 374 | [猜数字大小](../../problems/guess-number-higher-or-lower) | [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Easy |
-| 278 | [第一个错误的版本](../../problems/first-bad-version) | [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Easy |
-| 277 | [搜寻名人](../../problems/find-the-celebrity) 🔒 | [[贪心](../greedy/README.md)] [[图](../graph/README.md)] [[双指针](../two-pointers/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 158 | [用 Read4 读取 N 个字符 II](../../problems/read-n-characters-given-read4-ii-call-multiple-times) 🔒 | [[字符串](../string/README.md)] [[交互](../interactive/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 157 | [用 Read4 读取 N 个字符](../../problems/read-n-characters-given-read4) 🔒 | [[字符串](../string/README.md)] [[交互](../interactive/README.md)] [[模拟](../simulation/README.md)]  | Easy |
diff --git a/tag/iterator/README.md b/tag/iterator/README.md
deleted file mode 100644
index 0b206b29a..000000000
--- a/tag/iterator/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 迭代器
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1586 | [二叉搜索树迭代器 II](../../problems/binary-search-tree-iterator-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 1286 | [字母组合迭代器](../../problems/iterator-for-combination) | [[设计](../design/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 900 | [RLE 迭代器](../../problems/rle-iterator) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 604 | [迭代压缩字符串](../../problems/design-compressed-string-iterator) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[迭代器](../iterator/README.md)]  | Easy |
-| 341 | [扁平化嵌套列表迭代器](../../problems/flatten-nested-list-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 284 | [顶端迭代器](../../problems/peeking-iterator) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 281 | [锯齿迭代器](../../problems/zigzag-iterator) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 251 | [展开二维向量](../../problems/flatten-2d-vector) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 173 | [二叉搜索树迭代器](../../problems/binary-search-tree-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
diff --git a/tag/line-sweep/README.md b/tag/line-sweep/README.md
deleted file mode 100644
index 8cd80d13e..000000000
--- a/tag/line-sweep/README.md
+++ /dev/null
@@ -1,15 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 扫描线
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1851 | [包含每个查询的最小区间](../../problems/minimum-interval-to-include-each-query) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 850 | [矩形面积 II](../../problems/rectangle-area-ii) | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)]  | Hard |
-| 391 | [完美矩形](../../problems/perfect-rectangle) | [[数组](../array/README.md)] [[扫描线](../line-sweep/README.md)]  | Hard |
-| 218 | [天际线问题](../../problems/the-skyline-problem) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
diff --git a/tag/linked-list/README.md b/tag/linked-list/README.md
deleted file mode 100644
index 9a8521393..000000000
--- a/tag/linked-list/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 链表
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2130 | [链表最大孪生和](../../problems/maximum-twin-sum-of-a-linked-list) | [[栈](../stack/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 2095 | [删除链表的中间节点](../../problems/delete-the-middle-node-of-a-linked-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 2074 | [反转偶数长度组的节点](../../problems/reverse-nodes-in-even-length-groups) | [[链表](../linked-list/README.md)]  | Medium |
-| 2058 | [找出临界点之间的最小和最大距离](../../problems/find-the-minimum-and-maximum-number-of-nodes-between-critical-points) | [[链表](../linked-list/README.md)]  | Medium |
-| 2046 | [给按照绝对值排序的链表排序](../../problems/sort-linked-list-already-sorted-using-absolute-values) 🔒 | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1836 | [从未排序的链表中移除重复元素](../../problems/remove-duplicates-from-an-unsorted-linked-list) 🔒 | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 1721 | [交换链表中的节点](../../problems/swapping-nodes-in-a-linked-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1670 | [设计前中后队列](../../problems/design-front-middle-back-queue) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1669 | [合并两个链表](../../problems/merge-in-between-linked-lists) | [[链表](../linked-list/README.md)]  | Medium |
-| 1634 | [求两个多项式链表的和](../../problems/add-two-polynomials-represented-as-linked-lists) 🔒 | [[链表](../linked-list/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1474 | [删除链表 M 个节点之后的 N 个节点](../../problems/delete-n-nodes-after-m-nodes-of-a-linked-list) 🔒 | [[链表](../linked-list/README.md)]  | Easy |
-| 1472 | [设计浏览器历史记录](../../problems/design-browser-history) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 1367 | [二叉树中的列表](../../problems/linked-list-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1290 | [二进制链表转整数](../../problems/convert-binary-number-in-a-linked-list-to-integer) | [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1265 | [逆序打印不可变链表](../../problems/print-immutable-linked-list-in-reverse) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1206 | [设计跳表](../../problems/design-skiplist) | [[设计](../design/README.md)] [[链表](../linked-list/README.md)]  | Hard |
-| 1171 | [从链表中删去总和值为零的连续节点](../../problems/remove-zero-sum-consecutive-nodes-from-linked-list) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 1019 | [链表中的下一个更大节点](../../problems/next-greater-node-in-linked-list) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 876 | [链表的中间结点](../../problems/middle-of-the-linked-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 817 | [链表组件](../../problems/linked-list-components) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 725 | [分隔链表](../../problems/split-linked-list-in-parts) | [[链表](../linked-list/README.md)]  | Medium |
-| 716 | [最大栈](../../problems/max-stack) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)] [[有序集合](../ordered-set/README.md)]  | Easy |
-| 708 | [循环有序列表的插入](../../problems/insert-into-a-sorted-circular-linked-list) 🔒 | [[链表](../linked-list/README.md)]  | Medium |
-| 707 | [设计链表](../../problems/design-linked-list) | [[设计](../design/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 706 | [设计哈希映射](../../problems/design-hashmap) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 705 | [设计哈希集合](../../problems/design-hashset) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 641 | [设计循环双端队列](../../problems/design-circular-deque) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 622 | [设计循环队列](../../problems/design-circular-queue) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 460 | [LFU 缓存](../../problems/lfu-cache) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Hard |
-| 445 | [两数相加 II](../../problems/add-two-numbers-ii) | [[栈](../stack/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Medium |
-| 432 | [全 O(1) 的数据结构](../../problems/all-oone-data-structure) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Hard |
-| 430 | [扁平化多级双向链表](../../problems/flatten-a-multilevel-doubly-linked-list) | [[深度优先搜索](../depth-first-search/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 426 | [将二叉搜索树转化为排序的双向链表](../../problems/convert-binary-search-tree-to-sorted-doubly-linked-list) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 382 | [链表随机节点](../../problems/linked-list-random-node) | [[水塘抽样](../reservoir-sampling/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 379 | [电话目录管理系统](../../problems/design-phone-directory) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 369 | [给单链表加一](../../problems/plus-one-linked-list) 🔒 | [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Medium |
-| 355 | [设计推特](../../problems/design-twitter) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 328 | [奇偶链表](../../problems/odd-even-linked-list) | [[链表](../linked-list/README.md)]  | Medium |
-| 237 | [删除链表中的节点](../../problems/delete-node-in-a-linked-list) | [[链表](../linked-list/README.md)]  | Easy |
-| 234 | [回文链表](../../problems/palindrome-linked-list) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 206 | [反转链表](../../problems/reverse-linked-list) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Easy |
-| 203 | [移除链表元素](../../problems/remove-linked-list-elements) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Easy |
-| 160 | [相交链表](../../problems/intersection-of-two-linked-lists) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 148 | [排序链表](../../problems/sort-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)] [[分治](../divide-and-conquer/README.md)] [[排序](../sorting/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 147 | [对链表进行插入排序](../../problems/insertion-sort-list) | [[链表](../linked-list/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 146 | [LRU 缓存](../../problems/lru-cache) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 143 | [重排链表](../../problems/reorder-list) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 142 | [环形链表 II](../../problems/linked-list-cycle-ii) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 141 | [环形链表](../../problems/linked-list-cycle) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 138 | [复制带随机指针的链表](../../problems/copy-list-with-random-pointer) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 117 | [填充每个节点的下一个右侧节点指针 II](../../problems/populating-next-right-pointers-in-each-node-ii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 116 | [填充每个节点的下一个右侧节点指针](../../problems/populating-next-right-pointers-in-each-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 114 | [二叉树展开为链表](../../problems/flatten-binary-tree-to-linked-list) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 109 | [有序链表转换二叉搜索树](../../problems/convert-sorted-list-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 92 | [反转链表 II](../../problems/reverse-linked-list-ii) | [[链表](../linked-list/README.md)]  | Medium |
-| 86 | [分隔链表](../../problems/partition-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 83 | [删除排序链表中的重复元素](../../problems/remove-duplicates-from-sorted-list) | [[链表](../linked-list/README.md)]  | Easy |
-| 82 | [删除排序链表中的重复元素 II](../../problems/remove-duplicates-from-sorted-list-ii) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 61 | [旋转链表](../../problems/rotate-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 25 | [K 个一组翻转链表](../../problems/reverse-nodes-in-k-group) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Hard |
-| 24 | [两两交换链表中的节点](../../problems/swap-nodes-in-pairs) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 23 | [合并K个升序链表](../../problems/merge-k-sorted-lists) | [[链表](../linked-list/README.md)] [[分治](../divide-and-conquer/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 21 | [合并两个有序链表](../../problems/merge-two-sorted-lists) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Easy |
-| 19 | [删除链表的倒数第 N 个结点](../../problems/remove-nth-node-from-end-of-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 2 | [两数相加](../../problems/add-two-numbers) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Medium |
diff --git a/tag/map/README.md b/tag/map/README.md
deleted file mode 100644
index b8fa322dc..000000000
--- a/tag/map/README.md
+++ /dev/null
@@ -1,13 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    openset <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/openset                                 |-->
-<!--|@home      https://github.com/openset/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](https://github.com/openset/leetcode/blob/master/tag/README.md) > Map
-
-| # | 题名 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 855 | [考场就座](https://github.com/openset/leetcode/tree/master/problems/exam-room) | [[Map](https://github.com/openset/leetcode/tree/master/tag/map/README.md)]  | Medium |
-| 846 | [一手顺子](https://github.com/openset/leetcode/tree/master/problems/hand-of-straights) | [[Map](https://github.com/openset/leetcode/tree/master/tag/map/README.md)]  | Medium |
diff --git a/tag/math/README.md b/tag/math/README.md
deleted file mode 100644
index da2c17d3e..000000000
--- a/tag/math/README.md
+++ /dev/null
@@ -1,354 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 数学
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2169 | [得到 0 的操作数](../../problems/count-operations-to-obtain-zero) | [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2165 | [重排数字的最小值](../../problems/smallest-value-of-the-rearranged-number) | [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2162 | [设置时间的最少代价](../../problems/minimum-cost-to-set-cooking-time) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 2160 | [拆分数位后四位数字的最小和](../../problems/minimum-sum-of-four-digit-number-after-splitting-digits) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2152 | [Minimum Number of Lines to Cover Points](../../problems/minimum-number-of-lines-to-cover-points) 🔒 | [[位运算](../bit-manipulation/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 2147 | [分隔长廊的方案数](../../problems/number-of-ways-to-divide-a-long-corridor) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2139 | [得到目标值的最少行动次数](../../problems/minimum-moves-to-reach-target-score) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 2128 | [Remove All Ones With Row and Column Flips](../../problems/remove-all-ones-with-row-and-column-flips) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2125 | [银行中的激光束数量](../../problems/number-of-laser-beams-in-a-bank) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2119 | [反转两次的数字](../../problems/a-number-after-a-double-reversal) | [[数学](../math/README.md)]  | Easy |
-| 2117 | [一个区间内所有数乘积的缩写](../../problems/abbreviating-the-product-of-a-range) | [[数学](../math/README.md)]  | Hard |
-| 2110 | [股票平滑下跌阶段的数目](../../problems/number-of-smooth-descent-periods-of-a-stock) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2101 | [引爆最多的炸弹](../../problems/detonate-the-maximum-bombs) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 2083 | [求以相同字母开头和结尾的子串总数](../../problems/substrings-that-begin-and-end-with-the-same-letter) 🔒 | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2081 | [k 镜像数字的和](../../problems/sum-of-k-mirror-numbers) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2063 | [所有子字符串中的元音](../../problems/vowels-of-all-substrings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Medium |
-| 2048 | [下一个更大的数值平衡数](../../problems/next-greater-numerically-balanced-number) | [[数学](../math/README.md)] [[回溯](../backtracking/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 2038 | [如果相邻两个颜色均相同则删除当前颜色](../../problems/remove-colored-pieces-if-both-neighbors-are-the-same-color) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 2033 | [获取单值网格的最小操作数](../../problems/minimum-operations-to-make-a-uni-value-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2029 | [石子游戏 IX](../../problems/stone-game-ix) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 2028 | [找出缺失的观测数据](../../problems/find-missing-observations) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2019 | [解出数学表达式的学生分数](../../problems/the-score-of-students-solving-math-expression) | [[栈](../stack/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2001 | [可互换矩形的组数](../../problems/number-of-pairs-of-interchangeable-rectangles) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1998 | [数组的最大公因数排序](../../problems/gcd-sort-of-an-array) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1994 | [好子集的数目](../../problems/the-number-of-good-subsets) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1979 | [找出数组的最大公约数](../../problems/find-greatest-common-divisor-of-array) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1969 | [数组元素的最小非零乘积](../../problems/minimum-non-zero-product-of-the-array-elements) | [[贪心](../greedy/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1956 | [感染 K 种病毒所需的最短时间](../../problems/minimum-time-for-k-virus-variants-to-spread) 🔒 | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1954 | [收集足够苹果的最小花园周长](../../problems/minimum-garden-perimeter-to-collect-enough-apples) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1952 | [三除数](../../problems/three-divisors) | [[数学](../math/README.md)]  | Easy |
-| 1927 | [求和游戏](../../problems/sum-game) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1925 | [统计平方和三元组的数目](../../problems/count-square-sum-triples) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 1924 | [安装栅栏 II](../../problems/erect-the-fence-ii) 🔒 | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1922 | [统计好数字的数目](../../problems/count-good-numbers) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1916 | [统计为蚁群构筑房间的不同顺序](../../problems/count-ways-to-build-rooms-in-an-ant-colony) | [[树](../tree/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1908 | [Nim 游戏 II](../../problems/game-of-nim) 🔒 | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1904 | [你完成的完整对局数](../../problems/the-number-of-full-rounds-you-have-played) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1903 | [字符串中的最大奇数](../../problems/largest-odd-number-in-string) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1896 | [反转表达式值的最少操作次数](../../problems/minimum-cost-to-change-the-final-value-of-expression) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1884 | [鸡蛋掉落-两枚鸡蛋](../../problems/egg-drop-with-2-eggs-and-n-floors) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1878 | [矩阵中最大的三个菱形和](../../problems/get-biggest-three-rhombus-sums-in-a-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1872 | [石子游戏 VIII](../../problems/stone-game-viii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1866 | [恰有 K 根木棍可以看到的排列数目](../../problems/number-of-ways-to-rearrange-sticks-with-k-sticks-visible) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1863 | [找出所有子集的异或总和再求和](../../problems/sum-of-all-subset-xor-totals) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)]  | Easy |
-| 1862 | [向下取整数对和](../../problems/sum-of-floored-pairs) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1840 | [最高建筑高度](../../problems/maximum-building-height) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1837 | [K 进制表示下的各位数字总和](../../problems/sum-of-digits-in-base-k) | [[数学](../math/README.md)]  | Easy |
-| 1835 | [所有数对按位与结果的异或和](../../problems/find-xor-sum-of-all-pairs-bitwise-and) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1830 | [使字符串有序的最少操作次数](../../problems/minimum-number-of-operations-to-make-string-sorted) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1828 | [统计一个圆中点的数目](../../problems/queries-on-number-of-points-inside-a-circle) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1823 | [找出游戏的获胜者](../../problems/find-the-winner-of-the-circular-game) | [[递归](../recursion/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1822 | [数组元素积的符号](../../problems/sign-of-the-product-of-an-array) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1819 | [序列中不同最大公约数的数目](../../problems/number-of-different-subsequences-gcds) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1814 | [统计一个数组中好对子的数目](../../problems/count-nice-pairs-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1812 | [判断国际象棋棋盘中一个格子的颜色](../../problems/determine-color-of-a-chessboard-square) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1808 | [好因子的最大数目](../../problems/maximize-number-of-nice-divisors) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1806 | [还原排列的最少操作步数](../../problems/minimum-number-of-operations-to-reinitialize-a-permutation) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1799 | [N 次操作后的最大分数和](../../problems/maximize-score-after-n-operations) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1780 | [判断一个数字是否可以表示成三的幂的和](../../problems/check-if-number-is-a-sum-of-powers-of-three) | [[数学](../math/README.md)]  | Medium |
-| 1776 | [车队 II](../../problems/car-fleet-ii) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[单调栈](../monotonic-stack/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1766 | [互质树](../../problems/tree-of-coprimes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1759 | [统计同构子字符串的数目](../../problems/count-number-of-homogenous-substrings) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1753 | [移除石子的最大得分](../../problems/maximum-score-from-removing-stones) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1742 | [盒子中小球的最大数量](../../problems/maximum-number-of-balls-in-a-box) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1739 | [放置盒子](../../problems/building-boxes) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1735 | [生成乘积数组的方案数](../../problems/count-ways-to-make-array-with-product) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1728 | [猫和老鼠 II](../../problems/cat-and-mouse-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1716 | [计算力扣银行的钱](../../problems/calculate-money-in-leetcode-bank) | [[数学](../math/README.md)]  | Easy |
-| 1690 | [石子游戏 VII](../../problems/stone-game-vii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1688 | [比赛中的配对次数](../../problems/count-of-matches-in-tournament) | [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1686 | [石子游戏 VI](../../problems/stone-game-vi) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1685 | [有序数组中差绝对值之和](../../problems/sum-of-absolute-differences-in-a-sorted-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1680 | [连接连续二进制数字](../../problems/concatenation-of-consecutive-binary-numbers) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1648 | [销售价值减少的颜色球](../../problems/sell-diminishing-valued-colored-balls) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1643 | [第 K 条最小指令](../../problems/kth-smallest-instructions) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1634 | [求两个多项式链表的和](../../problems/add-two-polynomials-represented-as-linked-lists) 🔒 | [[链表](../linked-list/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1628 | [设计带解析函数的表达式树](../../problems/design-an-expression-tree-with-evaluate-function) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[数学](../math/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1627 | [带阈值的图连通性](../../problems/graph-connectivity-with-threshold) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1622 | [奇妙序列](../../problems/fancy-sequence) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1621 | [大小为 K 的不重叠线段的数目](../../problems/number-of-sets-of-k-non-overlapping-line-segments) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1610 | [可见点的最大数目](../../problems/maximum-number-of-visible-points) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 1588 | [所有奇数长度子数组的和](../../problems/sum-of-all-odd-length-subarrays) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1577 | [数的平方等于两数乘积的方法数](../../problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1573 | [分割字符串的方案数](../../problems/number-of-ways-to-split-a-string) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1563 | [石子游戏 V](../../problems/stone-game-v) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1561 | [你可以获得的最大硬币数目](../../problems/maximum-number-of-coins-you-can-get) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1551 | [使数组中所有元素相等的最小操作数](../../problems/minimum-operations-to-make-array-equal) | [[数学](../math/README.md)]  | Medium |
-| 1538 | [找出隐藏数组中出现次数最多的元素](../../problems/guess-the-majority-in-a-hidden-array) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1524 | [和为奇数的子数组数目](../../problems/number-of-sub-arrays-with-odd-sum) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1523 | [在区间范围内统计奇数数目](../../problems/count-odd-numbers-in-an-interval-range) | [[数学](../math/README.md)]  | Easy |
-| 1518 | [换酒问题](../../problems/water-bottles) | [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1515 | [服务中心的最佳位置](../../problems/best-position-for-a-service-centre) | [[几何](../geometry/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 1513 | [仅含 1 的子串数](../../problems/number-of-substrings-with-only-1s) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1512 | [好数对的数目](../../problems/number-of-good-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1510 | [石子游戏 IV](../../problems/stone-game-iv) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1493 | [删掉一个元素以后全为 1 的最长子数组](../../problems/longest-subarray-of-1s-after-deleting-one-element) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1492 | [n 的第 k 个因子](../../problems/the-kth-factor-of-n) | [[数学](../math/README.md)]  | Medium |
-| 1486 | [数组异或操作](../../problems/xor-operation-in-an-array) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1478 | [安排邮筒](../../problems/allocate-mailboxes) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1467 | [两个盒子中球的颜色数相同的概率](../../problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Hard |
-| 1453 | [圆形靶内的最大飞镖数量](../../problems/maximum-number-of-darts-inside-of-a-circular-dartboard) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1447 | [最简分数](../../problems/simplified-fractions) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1442 | [形成两个异或相等数组的三元组数目](../../problems/count-triplets-that-can-form-two-arrays-of-equal-xor) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1432 | [改变一个整数能得到的最大差值](../../problems/max-difference-you-can-get-from-changing-an-integer) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1427 | [字符串的左右移](../../problems/perform-string-shifts) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1406 | [石子游戏 III](../../problems/stone-game-iii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1401 | [圆和矩形是否有重叠](../../problems/circle-and-rectangle-overlapping) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1399 | [统计最大组的数目](../../problems/count-largest-group) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1390 | [四因数](../../problems/four-divisors) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1362 | [最接近的因数](../../problems/closest-divisors) | [[数学](../math/README.md)]  | Medium |
-| 1360 | [日期之间隔几天](../../problems/number-of-days-between-two-dates) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1359 | [有效的快递序列数目](../../problems/count-all-valid-pickup-and-delivery-options) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1352 | [最后 K 个数的乘积](../../problems/product-of-the-last-k-numbers) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1344 | [时钟指针的夹角](../../problems/angle-between-hands-of-a-clock) | [[数学](../math/README.md)]  | Medium |
-| 1342 | [将数字变成 0 的操作次数](../../problems/number-of-steps-to-reduce-a-number-to-zero) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1330 | [翻转子数组得到最大的数组值](../../problems/reverse-subarray-to-maximize-array-value) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1323 | [6 和 9 组成的最大数字](../../problems/maximum-69-number) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1317 | [将整数转换为两个无零整数的和](../../problems/convert-integer-to-the-sum-of-two-no-zero-integers) | [[数学](../math/README.md)]  | Easy |
-| 1307 | [口算难题](../../problems/verbal-arithmetic-puzzle) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1304 | [和为零的N个唯一整数](../../problems/find-n-unique-integers-sum-up-to-zero) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1290 | [二进制链表转整数](../../problems/convert-binary-number-in-a-linked-list-to-integer) | [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1281 | [整数的各位积和之差](../../problems/subtract-the-product-and-sum-of-digits-of-an-integer) | [[数学](../math/README.md)]  | Easy |
-| 1276 | [不浪费原料的汉堡制作方案](../../problems/number-of-burgers-with-no-waste-of-ingredients) | [[数学](../math/README.md)]  | Medium |
-| 1271 | [十六进制魔术数字](../../problems/hexspeak) 🔒 | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1266 | [访问所有点的最小时间](../../problems/minimum-time-visiting-all-points) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1259 | [不相交的握手](../../problems/handshakes-that-dont-cross) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1256 | [加密数字](../../problems/encode-number) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1252 | [奇数值单元格的数目](../../problems/cells-with-odd-values-in-a-matrix) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1250 | [检查「好数组」](../../problems/check-if-it-is-a-good-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1248 | [统计「优美子数组」](../../problems/count-number-of-nice-subarrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1247 | [交换字符使得字符串相同](../../problems/minimum-swaps-to-make-strings-equal) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1238 | [循环码排列](../../problems/circular-permutation-in-binary-representation) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1237 | [找出给定方程的正整数解](../../problems/find-positive-integer-solution-for-a-given-equation) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1232 | [缀点成线](../../problems/check-if-it-is-a-straight-line) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1230 | [抛掷硬币](../../problems/toss-strange-coins) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 1228 | [等差数列中缺失的数字](../../problems/missing-number-in-arithmetic-progression) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1227 | [飞机座位分配概率](../../problems/airplane-seat-assignment-probability) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 1217 | [玩筹码](../../problems/minimum-cost-to-move-chips-to-the-same-position) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1201 | [丑数 III](../../problems/ugly-number-iii) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1199 | [建造街区的最短时间](../../problems/minimum-time-to-build-blocks) 🔒 | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1185 | [一周中的第几天](../../problems/day-of-the-week) | [[数学](../math/README.md)]  | Easy |
-| 1180 | [统计只含单一字母的子串](../../problems/count-substrings-with-only-one-distinct-letter) 🔒 | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1175 | [质数排列](../../problems/prime-arrangements) | [[数学](../math/README.md)]  | Easy |
-| 1154 | [一年中的第几天](../../problems/day-of-the-year) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1140 | [石子游戏 II](../../problems/stone-game-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 1137 | [第 N 个泰波那契数](../../problems/n-th-tribonacci-number) | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 1134 | [阿姆斯特朗数](../../problems/armstrong-number) 🔒 | [[数学](../math/README.md)]  | Easy |
-| 1131 | [绝对值表达式的最大值](../../problems/maximum-of-absolute-value-expression) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1118 | [一月有多少天](../../problems/number-of-days-in-a-month) 🔒 | [[数学](../math/README.md)]  | Easy |
-| 1104 | [二叉树寻路](../../problems/path-in-zigzag-labelled-binary-tree) | [[树](../tree/README.md)] [[数学](../math/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1103 | [分糖果 II](../../problems/distribute-candies-to-people) | [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1093 | [大样本统计](../../problems/statistics-from-a-large-sample) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 1088 | [易混淆数 II](../../problems/confusing-number-ii) 🔒 | [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1085 | [最小元素各数位之和](../../problems/sum-of-digits-in-the-minimum-number) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1073 | [负二进制数相加](../../problems/adding-two-negabinary-numbers) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1071 | [字符串的最大公因子](../../problems/greatest-common-divisor-of-strings) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1067 | [范围内的数字计数](../../problems/digit-count-in-range) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1058 | [最小化舍入误差以满足目标](../../problems/minimize-rounding-error-to-meet-target) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1056 | [易混淆数](../../problems/confusing-number) 🔒 | [[数学](../math/README.md)]  | Easy |
-| 1041 | [困于环中的机器人](../../problems/robot-bounded-in-circle) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1040 | [移动石子直到连续 II](../../problems/moving-stones-until-consecutive-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1037 | [有效的回旋镖](../../problems/valid-boomerang) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Easy |
-| 1033 | [移动石子直到连续](../../problems/moving-stones-until-consecutive) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1030 | [距离顺序排列矩阵单元格](../../problems/matrix-cells-in-distance-order) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1025 | [除数博弈](../../problems/divisor-game) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Easy |
-| 1017 | [负二进制转换](../../problems/convert-to-base-2) | [[数学](../math/README.md)]  | Medium |
-| 1015 | [可被 K 整除的最小整数](../../problems/smallest-integer-divisible-by-k) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1012 | [至少有 1 位重复的数字](../../problems/numbers-with-repeated-digits) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1006 | [笨阶乘](../../problems/clumsy-factorial) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 996 | [正方形数组的数目](../../problems/number-of-squareful-arrays) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 991 | [坏了的计算器](../../problems/broken-calculator) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 989 | [数组形式的整数加法](../../problems/add-to-array-form-of-integer) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 976 | [三角形的最大周长](../../problems/largest-perimeter-triangle) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 973 | [最接近原点的 K 个点](../../problems/k-closest-points-to-origin) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 972 | [相等的有理数](../../problems/equal-rational-numbers) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 970 | [强整数](../../problems/powerful-integers) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 964 | [表示数字的最少运算符](../../problems/least-operators-to-express-number) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 963 | [最小面积矩形 II](../../problems/minimum-area-rectangle-ii) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 957 | [N 天后的牢房](../../problems/prison-cells-after-n-days) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 952 | [按公因数计算最大组件大小](../../problems/largest-component-size-by-common-factor) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 942 | [增减字符串匹配](../../problems/di-string-match) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 939 | [最小面积矩形](../../problems/minimum-area-rectangle) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 932 | [漂亮数组](../../problems/beautiful-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)]  | Medium |
-| 927 | [三等分](../../problems/three-equal-parts) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 920 | [播放列表的数量](../../problems/number-of-music-playlists) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 914 | [卡牌分组](../../problems/x-of-a-kind-in-a-deck-of-cards) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Easy |
-| 913 | [猫和老鼠](../../problems/cat-and-mouse) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 910 | [最小差值 II](../../problems/smallest-range-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 908 | [最小差值 I](../../problems/smallest-range-i) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 906 | [超级回文数](../../problems/super-palindromes) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 902 | [最大为 N 的数字组合](../../problems/numbers-at-most-n-given-digit-set) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 899 | [有序队列](../../problems/orderly-queue) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 892 | [三维形体的表面积](../../problems/surface-area-of-3d-shapes) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 891 | [子序列宽度之和](../../problems/sum-of-subsequence-widths) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 887 | [鸡蛋掉落](../../problems/super-egg-drop) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 883 | [三维形体投影面积](../../problems/projection-area-of-3d-shapes) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 878 | [第 N 个神奇数字](../../problems/nth-magical-number) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 877 | [石子游戏](../../problems/stone-game) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 869 | [重新排序得到 2 的幂](../../problems/reordered-power-of-2) | [[数学](../math/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 868 | [二进制间距](../../problems/binary-gap) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 866 | [回文素数](../../problems/prime-palindrome) | [[数学](../math/README.md)]  | Medium |
-| 858 | [镜面反射](../../problems/mirror-reflection) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 843 | [猜猜这个单词](../../problems/guess-the-word) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[博弈](../game-theory/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 840 | [矩阵中的幻方](../../problems/magic-squares-in-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 837 | [新 21 点](../../problems/new-21-game) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 836 | [矩形重叠](../../problems/rectangle-overlap) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Easy |
-| 829 | [连续整数求和](../../problems/consecutive-numbers-sum) | [[数学](../math/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 812 | [最大三角形面积](../../problems/largest-triangle-area) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 810 | [黑板异或游戏](../../problems/chalkboard-xor-game) | [[位运算](../bit-manipulation/README.md)] [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 808 | [分汤](../../problems/soup-servings) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 805 | [数组的均值分割](../../problems/split-array-with-same-average) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 800 | [相似 RGB 颜色](../../problems/similar-rgb-color) 🔒 | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 793 | [阶乘函数后 K 个零](../../problems/preimage-size-of-factorial-zeroes-function) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 789 | [逃脱阻碍者](../../problems/escape-the-ghosts) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 788 | [旋转数字](../../problems/rotated-digits) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 782 | [变为棋盘](../../problems/transform-to-chessboard) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 781 | [森林中的兔子](../../problems/rabbits-in-forest) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 780 | [到达终点](../../problems/reaching-points) | [[数学](../math/README.md)]  | Hard |
-| 779 | [第K个语法符号](../../problems/k-th-symbol-in-grammar) | [[位运算](../bit-manipulation/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 775 | [全局倒置与局部倒置](../../problems/global-and-local-inversions) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 772 | [基本计算器 III](../../problems/basic-calculator-iii) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 770 | [基本计算器 IV](../../problems/basic-calculator-iv) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 762 | [二进制表示中质数个计算置位](../../problems/prime-number-of-set-bits-in-binary-representation) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 754 | [到达终点数字](../../problems/reach-a-number) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 750 | [角矩形的数量](../../problems/number-of-corner-rectangles) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 738 | [单调递增的数字](../../problems/monotone-increasing-digits) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 728 | [自除数](../../problems/self-dividing-numbers) | [[数学](../math/README.md)]  | Easy |
-| 710 | [黑名单中的随机数](../../problems/random-pick-with-blacklist) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 679 | [24 点游戏](../../problems/24-game) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 672 | [灯泡开关 Ⅱ](../../problems/bulb-switcher-ii) | [[位运算](../bit-manipulation/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Medium |
-| 670 | [最大交换](../../problems/maximum-swap) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 667 | [优美的排列 II](../../problems/beautiful-arrangement-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 660 | [移除 9](../../problems/remove-9) 🔒 | [[数学](../math/README.md)]  | Hard |
-| 651 | [4键键盘](../../problems/4-keys-keyboard) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 650 | [只有两个键的键盘](../../problems/2-keys-keyboard) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 640 | [求解方程](../../problems/solve-the-equation) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 634 | [寻找数组的错位排列](../../problems/find-the-derangement-of-an-array) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 633 | [平方数之和](../../problems/sum-of-square-numbers) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 628 | [三个数的最大乘积](../../problems/maximum-product-of-three-numbers) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 625 | [最小因式分解](../../problems/minimum-factorization) 🔒 | [[贪心](../greedy/README.md)] [[数学](../math/README.md)]  | Medium |
-| 598 | [范围求和 II](../../problems/range-addition-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 593 | [有效的正方形](../../problems/valid-square) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 592 | [分数加减运算](../../problems/fraction-addition-and-subtraction) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 587 | [安装栅栏](../../problems/erect-the-fence) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 573 | [松鼠模拟](../../problems/squirrel-simulation) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 564 | [寻找最近的回文数](../../problems/find-the-closest-palindrome) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 556 | [下一个更大元素 III](../../problems/next-greater-element-iii) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 553 | [最优除法](../../problems/optimal-division) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 539 | [最小时间差](../../problems/minimum-time-difference) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 537 | [复数乘法](../../problems/complex-number-multiplication) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 528 | [按权重随机选择](../../problems/random-pick-with-weight) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 523 | [连续的子数组和](../../problems/continuous-subarray-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 519 | [随机翻转矩阵](../../problems/random-flip-matrix) | [[水塘抽样](../reservoir-sampling/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 509 | [斐波那契数](../../problems/fibonacci-number) | [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 507 | [完美数](../../problems/perfect-number) | [[数学](../math/README.md)]  | Easy |
-| 504 | [七进制数](../../problems/base-7) | [[数学](../math/README.md)]  | Easy |
-| 497 | [非重叠矩形中的随机点](../../problems/random-point-in-non-overlapping-rectangles) | [[水塘抽样](../reservoir-sampling/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 492 | [构造矩形](../../problems/construct-the-rectangle) | [[数学](../math/README.md)]  | Easy |
-| 486 | [预测赢家](../../problems/predict-the-winner) | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 483 | [最小好进制](../../problems/smallest-good-base) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 479 | [最大回文数乘积](../../problems/largest-palindrome-product) | [[数学](../math/README.md)]  | Hard |
-| 478 | [在圆内随机生成点](../../problems/generate-random-point-in-a-circle) | [[几何](../geometry/README.md)] [[数学](../math/README.md)] [[拒绝采样](../rejection-sampling/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 477 | [汉明距离总和](../../problems/total-hamming-distance) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 470 | [用 Rand7() 实现 Rand10()](../../problems/implement-rand10-using-rand7) | [[数学](../math/README.md)] [[拒绝采样](../rejection-sampling/README.md)] [[概率与统计](../probability-and-statistics/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 469 | [凸多边形](../../problems/convex-polygon) 🔒 | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 464 | [我能赢吗](../../problems/can-i-win) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 462 | [最少移动次数使数组元素相等 II](../../problems/minimum-moves-to-equal-array-elements-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 458 | [可怜的小猪](../../problems/poor-pigs) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 453 | [最小操作次数使数组元素相等](../../problems/minimum-moves-to-equal-array-elements) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 447 | [回旋镖的数量](../../problems/number-of-boomerangs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 445 | [两数相加 II](../../problems/add-two-numbers-ii) | [[栈](../stack/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Medium |
-| 441 | [排列硬币](../../problems/arranging-coins) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 423 | [从英文中重建数字](../../problems/reconstruct-original-digits-from-english) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 415 | [字符串相加](../../problems/add-strings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 412 | [Fizz Buzz](../../problems/fizz-buzz) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 405 | [数字转换为十六进制数](../../problems/convert-a-number-to-hexadecimal) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Easy |
-| 400 | [第 N 位数字](../../problems/nth-digit) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 398 | [随机数索引](../../problems/random-pick-index) | [[水塘抽样](../reservoir-sampling/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 396 | [旋转函数](../../problems/rotate-function) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 390 | [消除游戏](../../problems/elimination-game) | [[数学](../math/README.md)]  | Medium |
-| 384 | [打乱数组](../../problems/shuffle-an-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 382 | [链表随机节点](../../problems/linked-list-random-node) | [[水塘抽样](../reservoir-sampling/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 381 | [O(1) 时间插入、删除和获取随机元素 - 允许重复](../../problems/insert-delete-getrandom-o1-duplicates-allowed) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 380 | [O(1) 时间插入、删除和获取随机元素](../../problems/insert-delete-getrandom-o1) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 375 | [猜数字大小 II](../../problems/guess-number-higher-or-lower-ii) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 372 | [超级次方](../../problems/super-pow) | [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)]  | Medium |
-| 371 | [两整数之和](../../problems/sum-of-two-integers) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Medium |
-| 369 | [给单链表加一](../../problems/plus-one-linked-list) 🔒 | [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Medium |
-| 368 | [最大整除子集](../../problems/largest-divisible-subset) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 367 | [有效的完全平方数](../../problems/valid-perfect-square) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 365 | [水壶问题](../../problems/water-and-jug-problem) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Medium |
-| 360 | [有序转化数组](../../problems/sort-transformed-array) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 357 | [计算各个位数不同的数字个数](../../problems/count-numbers-with-unique-digits) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 356 | [直线镜像](../../problems/line-reflection) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Medium |
-| 343 | [整数拆分](../../problems/integer-break) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 342 | [4的幂](../../problems/power-of-four) | [[位运算](../bit-manipulation/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Easy |
-| 335 | [路径交叉](../../problems/self-crossing) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 326 | [3 的幂](../../problems/power-of-three) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Easy |
-| 319 | [灯泡开关](../../problems/bulb-switcher) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)]  | Medium |
-| 313 | [超级丑数](../../problems/super-ugly-number) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 296 | [最佳的碰头地点](../../problems/best-meeting-point) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 294 | [翻转游戏 II](../../problems/flip-game-ii) 🔒 | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 292 | [Nim 游戏](../../problems/nim-game) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)]  | Easy |
-| 282 | [给表达式添加运算符](../../problems/expression-add-operators) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 279 | [完全平方数](../../problems/perfect-squares) | [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 273 | [整数转换英文表示](../../problems/integer-to-english-words) | [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 268 | [丢失的数字](../../problems/missing-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 264 | [丑数 II](../../problems/ugly-number-ii) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 263 | [丑数](../../problems/ugly-number) | [[数学](../math/README.md)]  | Easy |
-| 258 | [各位相加](../../problems/add-digits) | [[数学](../math/README.md)] [[数论](../number-theory/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 241 | [为运算表达式设计优先级](../../problems/different-ways-to-add-parentheses) | [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 233 | [数字 1 的个数](../../problems/number-of-digit-one) | [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 231 | [2 的幂](../../problems/power-of-two) | [[位运算](../bit-manipulation/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Easy |
-| 227 | [基本计算器 II](../../problems/basic-calculator-ii) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 224 | [基本计算器](../../problems/basic-calculator) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 223 | [矩形面积](../../problems/rectangle-area) | [[几何](../geometry/README.md)] [[数学](../math/README.md)]  | Medium |
-| 204 | [计数质数](../../problems/count-primes) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[枚举](../enumeration/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 202 | [快乐数](../../problems/happy-number) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 189 | [轮转数组](../../problems/rotate-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 172 | [阶乘后的零](../../problems/factorial-trailing-zeroes) | [[数学](../math/README.md)]  | Medium |
-| 171 | [Excel 表列序号](../../problems/excel-sheet-column-number) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 168 | [Excel表列名称](../../problems/excel-sheet-column-title) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 166 | [分数到小数](../../problems/fraction-to-recurring-decimal) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 150 | [逆波兰表达式求值](../../problems/evaluate-reverse-polish-notation) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 149 | [直线上最多的点数](../../problems/max-points-on-a-line) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)]  | Hard |
-| 96 | [不同的二叉搜索树](../../problems/unique-binary-search-trees) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 89 | [格雷编码](../../problems/gray-code) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 70 | [爬楼梯](../../problems/climbing-stairs) | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 69 | [x 的平方根 ](../../problems/sqrtx) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)]  | Easy |
-| 67 | [二进制求和](../../problems/add-binary) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 66 | [加一](../../problems/plus-one) | [[数组](../array/README.md)] [[数学](../math/README.md)]  | Easy |
-| 62 | [不同路径](../../problems/unique-paths) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Medium |
-| 60 | [排列序列](../../problems/permutation-sequence) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Hard |
-| 50 | [Pow(x, n)](../../problems/powx-n) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 48 | [旋转图像](../../problems/rotate-image) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 43 | [字符串相乘](../../problems/multiply-strings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 29 | [两数相除](../../problems/divide-two-integers) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)]  | Medium |
-| 13 | [罗马数字转整数](../../problems/roman-to-integer) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 12 | [整数转罗马数字](../../problems/integer-to-roman) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 9 | [回文数](../../problems/palindrome-number) | [[数学](../math/README.md)]  | Easy |
-| 7 | [整数反转](../../problems/reverse-integer) | [[数学](../math/README.md)]  | Medium |
-| 2 | [两数相加](../../problems/add-two-numbers) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Medium |
diff --git a/tag/matrix/README.md b/tag/matrix/README.md
deleted file mode 100644
index 8b27d5128..000000000
--- a/tag/matrix/README.md
+++ /dev/null
@@ -1,169 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 矩阵
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2146 | [价格范围内最高排名的 K 样物品](../../problems/k-highest-ranked-items-within-a-price-range) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2133 | [检查是否每一行每一列都包含全部整数](../../problems/check-if-every-row-and-column-contains-all-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 2132 | [用邮票贴满网格图](../../problems/stamping-the-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 2128 | [Remove All Ones With Row and Column Flips](../../problems/remove-all-ones-with-row-and-column-flips) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2125 | [银行中的激光束数量](../../problems/number-of-laser-beams-in-a-bank) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2123 | [Minimum Operations to Remove Adjacent Ones in Matrix](../../problems/minimum-operations-to-remove-adjacent-ones-in-matrix) 🔒 | [[图](../graph/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 2088 | [统计农场中肥沃金字塔的数目](../../problems/count-fertile-pyramids-in-a-land) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 2087 | [网格图中机器人回家的最小代价](../../problems/minimum-cost-homecoming-of-a-robot-in-a-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2061 | [扫地机器人清扫过的空间个数](../../problems/number-of-spaces-cleaning-robot-cleaned) 🔒 | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2033 | [获取单值网格的最小操作数](../../problems/minimum-operations-to-make-a-uni-value-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2022 | [将一维数组转变成二维数组](../../problems/convert-1d-array-into-2d-array) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2018 | [判断单词是否能放入填字游戏内](../../problems/check-if-word-can-be-placed-in-crossword) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2017 | [网格游戏](../../problems/grid-game) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1992 | [找到所有的农场组](../../problems/find-all-groups-of-farmland) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1981 | [最小化目标值与所选元素的差](../../problems/minimize-the-difference-between-target-and-chosen-elements) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1975 | [最大方阵和](../../problems/maximum-matrix-sum) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1970 | [你能穿过矩阵的最后一天](../../problems/last-day-where-you-can-still-cross) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1958 | [检查操作是否合法](../../problems/check-if-move-is-legal) | [[数组](../array/README.md)] [[枚举](../enumeration/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1926 | [迷宫中离入口最近的出口](../../problems/nearest-exit-from-entrance-in-maze) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1914 | [循环轮转矩阵](../../problems/cyclically-rotating-a-grid) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1905 | [统计子岛屿](../../problems/count-sub-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1901 | [找出顶峰元素 II](../../problems/find-a-peak-element-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1895 | [最大的幻方](../../problems/largest-magic-square) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1886 | [判断矩阵经轮转后是否一致](../../problems/determine-whether-matrix-can-be-obtained-by-rotation) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1878 | [矩阵中最大的三个菱形和](../../problems/get-biggest-three-rhombus-sums-in-a-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1861 | [旋转盒子](../../problems/rotating-the-box) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1820 | [最多邀请的个数](../../problems/maximum-number-of-accepted-invitations) 🔒 | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1765 | [地图中的最高点](../../problems/map-of-highest-peak) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1738 | [找出第 K 大的异或坐标值](../../problems/find-kth-largest-xor-coordinate-value) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[快速选择](../quickselect/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1730 | [获取食物的最短路径](../../problems/shortest-path-to-get-food) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1727 | [重新排列后的最大子矩阵](../../problems/largest-submatrix-with-rearrangements) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1706 | [球会落何处](../../problems/where-will-the-ball-fall) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1672 | [最富有客户的资产总量](../../problems/richest-customer-wealth) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1632 | [矩阵转换后的秩](../../problems/rank-transform-of-a-matrix) | [[贪心](../greedy/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1631 | [最小体力消耗路径](../../problems/path-with-minimum-effort) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1605 | [给定行和列的和求可行矩阵](../../problems/find-valid-matrix-given-row-and-column-sums) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1595 | [连通两组点的最小成本](../../problems/minimum-cost-to-connect-two-groups-of-points) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1594 | [矩阵的最大非负积](../../problems/maximum-non-negative-product-in-a-matrix) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1591 | [奇怪的打印机 II](../../problems/strange-printer-ii) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1582 | [二进制矩阵中的特殊位置](../../problems/special-positions-in-a-binary-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1572 | [矩阵对角线元素的和](../../problems/matrix-diagonal-sum) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1568 | [使陆地分离的最少天数](../../problems/minimum-number-of-days-to-disconnect-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
-| 1559 | [二维网格图中探测环](../../problems/detect-cycles-in-2d-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1536 | [排布二进制网格的最少交换次数](../../problems/minimum-swaps-to-arrange-a-binary-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1504 | [统计全 1 子矩形](../../problems/count-submatrices-with-all-ones) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1476 | [子矩形查询](../../problems/subrectangle-queries) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1463 | [摘樱桃 II](../../problems/cherry-pickup-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1444 | [切披萨的方案数](../../problems/number-of-ways-of-cutting-a-pizza) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1439 | [有序矩阵中的第 k 个最小数组和](../../problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1428 | [至少有一个 1 的最左端列](../../problems/leftmost-column-with-at-least-a-one) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1391 | [检查网格中是否存在有效路径](../../problems/check-if-there-is-a-valid-path-in-a-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1380 | [矩阵中的幸运数](../../problems/lucky-numbers-in-a-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1368 | [使网格图至少有一条有效路径的最小代价](../../problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1351 | [统计有序矩阵中的负数](../../problems/count-negative-numbers-in-a-sorted-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 1349 | [参加考试的最大学生数](../../problems/maximum-students-taking-exam) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1337 | [矩阵中战斗力最弱的 K 行](../../problems/the-k-weakest-rows-in-a-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 1329 | [将矩阵按对角线排序](../../problems/sort-the-matrix-diagonally) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1314 | [矩阵区域和](../../problems/matrix-block-sum) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1301 | [最大得分的路径数目](../../problems/number-of-paths-with-max-score) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1293 | [网格中的最短路径](../../problems/shortest-path-in-a-grid-with-obstacles-elimination) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1292 | [元素和小于等于阈值的正方形的最大边长](../../problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1289 | [下降路径最小和  II](../../problems/minimum-falling-path-sum-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1284 | [转化为全零矩阵的最少反转次数](../../problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix) | [[位运算](../bit-manipulation/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1277 | [统计全为 1 的正方形子矩阵](../../problems/count-square-submatrices-with-all-ones) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1275 | [找出井字棋的获胜者](../../problems/find-winner-on-a-tic-tac-toe-game) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1267 | [统计参与通信的服务器](../../problems/count-servers-that-communicate) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1263 | [推箱子](../../problems/minimum-moves-to-move-a-box-to-their-target-location) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1260 | [二维网格迁移](../../problems/shift-2d-grid) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1254 | [统计封闭岛屿的数目](../../problems/number-of-closed-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1253 | [重构 2 行二进制矩阵](../../problems/reconstruct-a-2-row-binary-matrix) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1222 | [可以攻击国王的皇后](../../problems/queens-that-can-attack-the-king) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1219 | [黄金矿工](../../problems/path-with-maximum-gold) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1210 | [穿过迷宫的最少移动次数](../../problems/minimum-moves-to-reach-target-with-rotations) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1198 | [找出所有行中最小公共元素](../../problems/find-smallest-common-element-in-all-rows) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1162 | [地图分析](../../problems/as-far-from-land-as-possible) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1139 | [最大的以 1 为边界的正方形](../../problems/largest-1-bordered-square) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1102 | [得分最高的路径](../../problems/path-with-maximum-minimum-value) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1091 | [二进制矩阵中的最短路径](../../problems/shortest-path-in-binary-matrix) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1074 | [元素和为目标值的子矩阵数量](../../problems/number-of-submatrices-that-sum-to-target) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1072 | [按列翻转得到最大值等行数](../../problems/flip-columns-for-maximum-number-of-equal-rows) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1034 | [边界着色](../../problems/coloring-a-border) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1030 | [距离顺序排列矩阵单元格](../../problems/matrix-cells-in-distance-order) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1020 | [飞地的数量](../../problems/number-of-enclaves) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 999 | [可以被一步捕获的棋子数](../../problems/available-captures-for-rook) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 994 | [腐烂的橘子](../../problems/rotting-oranges) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 980 | [不同路径 III](../../problems/unique-paths-iii) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 934 | [最短的桥](../../problems/shortest-bridge) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 931 | [下降路径最小和](../../problems/minimum-falling-path-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 928 | [尽量减少恶意软件的传播 II](../../problems/minimize-malware-spread-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 924 | [尽量减少恶意软件的传播](../../problems/minimize-malware-spread) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 909 | [蛇梯棋](../../problems/snakes-and-ladders) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 892 | [三维形体的表面积](../../problems/surface-area-of-3d-shapes) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 885 | [螺旋矩阵 III](../../problems/spiral-matrix-iii) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 883 | [三维形体投影面积](../../problems/projection-area-of-3d-shapes) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 867 | [转置矩阵](../../problems/transpose-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 861 | [翻转矩阵后的得分](../../problems/score-after-flipping-matrix) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 840 | [矩阵中的幻方](../../problems/magic-squares-in-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 835 | [图像重叠](../../problems/image-overlap) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 832 | [翻转图像](../../problems/flipping-an-image) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 827 | [最大人工岛](../../problems/making-a-large-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 807 | [保持城市天际线](../../problems/max-increase-to-keep-city-skyline) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 803 | [打砖块](../../problems/bricks-falling-when-hit) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 782 | [变为棋盘](../../problems/transform-to-chessboard) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 778 | [水位上升的泳池中游泳](../../problems/swim-in-rising-water) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 773 | [滑动谜题](../../problems/sliding-puzzle) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 766 | [托普利茨矩阵](../../problems/toeplitz-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 750 | [角矩形的数量](../../problems/number-of-corner-rectangles) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 749 | [隔离病毒](../../problems/contain-virus) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 741 | [摘樱桃](../../problems/cherry-pickup) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 733 | [图像渲染](../../problems/flood-fill) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 723 | [粉碎糖果](../../problems/candy-crush) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 695 | [岛屿的最大面积](../../problems/max-area-of-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 675 | [为高尔夫比赛砍树](../../problems/cut-off-trees-for-golf-event) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 661 | [图片平滑器](../../problems/image-smoother) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 568 | [最大休假天数](../../problems/maximum-vacation-days) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 566 | [重塑矩阵](../../problems/reshape-the-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 562 | [矩阵中最长的连续1线段](../../problems/longest-line-of-consecutive-one-in-matrix) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 542 | [01 矩阵](../../problems/01-matrix) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 533 | [孤独像素 II](../../problems/lonely-pixel-ii) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 531 | [孤独像素 I](../../problems/lonely-pixel-i) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 529 | [扫雷游戏](../../problems/minesweeper) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 498 | [对角线遍历](../../problems/diagonal-traverse) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 463 | [岛屿的周长](../../problems/island-perimeter) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 427 | [建立四叉树](../../problems/construct-quad-tree) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 422 | [有效的单词方块](../../problems/valid-word-square) 🔒 | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Easy |
-| 419 | [甲板上的战舰](../../problems/battleships-in-a-board) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 417 | [太平洋大西洋水流问题](../../problems/pacific-atlantic-water-flow) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 407 | [接雨水 II](../../problems/trapping-rain-water-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 378 | [有序矩阵中第 K 小的元素](../../problems/kth-smallest-element-in-a-sorted-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 363 | [矩形区域不超过 K 的最大数值和](../../problems/max-sum-of-rectangle-no-larger-than-k) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 361 | [轰炸敌人](../../problems/bomb-enemy) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 353 | [贪吃蛇](../../problems/design-snake-game) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 348 | [设计井字棋](../../problems/design-tic-tac-toe) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 317 | [离建筑物最近的距离](../../problems/shortest-distance-from-all-buildings) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 311 | [稀疏矩阵的乘法](../../problems/sparse-matrix-multiplication) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 308 | [二维区域和检索 - 可变](../../problems/range-sum-query-2d-mutable) 🔒 | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 304 | [二维区域和检索 - 矩阵不可变](../../problems/range-sum-query-2d-immutable) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 302 | [包含全部黑色像素的最小矩形](../../problems/smallest-rectangle-enclosing-black-pixels) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 296 | [最佳的碰头地点](../../problems/best-meeting-point) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 289 | [生命游戏](../../problems/game-of-life) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 286 | [墙与门](../../problems/walls-and-gates) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 240 | [搜索二维矩阵 II](../../problems/search-a-2d-matrix-ii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 221 | [最大正方形](../../problems/maximal-square) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 212 | [单词搜索 II](../../problems/word-search-ii) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 200 | [岛屿数量](../../problems/number-of-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 174 | [地下城游戏](../../problems/dungeon-game) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 130 | [被围绕的区域](../../problems/surrounded-regions) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 85 | [最大矩形](../../problems/maximal-rectangle) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 79 | [单词搜索](../../problems/word-search) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 74 | [搜索二维矩阵](../../problems/search-a-2d-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 73 | [矩阵置零](../../problems/set-matrix-zeroes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 64 | [最小路径和](../../problems/minimum-path-sum) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 63 | [不同路径 II](../../problems/unique-paths-ii) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 59 | [螺旋矩阵 II](../../problems/spiral-matrix-ii) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 54 | [螺旋矩阵](../../problems/spiral-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 48 | [旋转图像](../../problems/rotate-image) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 37 | [解数独](../../problems/sudoku-solver) | [[数组](../array/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 36 | [有效的数独](../../problems/valid-sudoku) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
diff --git a/tag/meet-in-the-middle/README.md b/tag/meet-in-the-middle/README.md
deleted file mode 100644
index 0b779f115..000000000
--- a/tag/meet-in-the-middle/README.md
+++ /dev/null
@@ -1,11 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > Meet In The Middle
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
diff --git a/tag/memoization/README.md b/tag/memoization/README.md
deleted file mode 100644
index 377f20f06..000000000
--- a/tag/memoization/README.md
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 记忆化搜索
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2019 | [解出数学表达式的学生分数](../../problems/the-score-of-students-solving-math-expression) | [[栈](../stack/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1900 | [最佳运动员的比拼回合](../../problems/the-earliest-and-latest-rounds-where-players-compete) | [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1857 | [有向图中最大颜色值](../../problems/largest-color-value-in-a-directed-graph) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)] [[计数](../counting/README.md)]  | Hard |
-| 1815 | [得到新鲜甜甜圈的最多组数](../../problems/maximum-number-of-groups-getting-fresh-donuts) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1728 | [猫和老鼠 II](../../problems/cat-and-mouse-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 1659 | [最大化网格幸福感](../../problems/maximize-grid-happiness) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1611 | [使整数变为 0 的最少操作次数](../../problems/minimum-one-bit-operations-to-make-integers-zero) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1575 | [统计所有可行路径](../../problems/count-all-possible-routes) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1553 | [吃掉 N 个橘子的最少天数](../../problems/minimum-number-of-days-to-eat-n-oranges) | [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1444 | [切披萨的方案数](../../problems/number-of-ways-of-cutting-a-pizza) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1387 | [将整数按权重排序](../../problems/sort-integers-by-the-power-value) | [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1137 | [第 N 个泰波那契数](../../problems/n-th-tribonacci-number) | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 913 | [猫和老鼠](../../problems/cat-and-mouse) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Hard |
-| 894 | [所有可能的满二叉树](../../problems/all-possible-full-binary-trees) | [[树](../tree/README.md)] [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 698 | [划分为k个相等的子集](../../problems/partition-to-k-equal-sum-subsets) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 638 | [大礼包](../../problems/shopping-offers) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 546 | [移除盒子](../../problems/remove-boxes) | [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 509 | [斐波那契数](../../problems/fibonacci-number) | [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 488 | [祖玛游戏](../../problems/zuma-game) | [[广度优先搜索](../breadth-first-search/README.md)] [[记忆化搜索](../memoization/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 464 | [我能赢吗](../../problems/can-i-win) | [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 397 | [整数替换](../../problems/integer-replacement) | [[贪心](../greedy/README.md)] [[位运算](../bit-manipulation/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 329 | [矩阵中的最长递增路径](../../problems/longest-increasing-path-in-a-matrix) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 294 | [翻转游戏 II](../../problems/flip-game-ii) 🔒 | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 241 | [为运算表达式设计优先级](../../problems/different-ways-to-add-parentheses) | [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 140 | [单词拆分 II](../../problems/word-break-ii) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 139 | [单词拆分](../../problems/word-break) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 70 | [爬楼梯](../../problems/climbing-stairs) | [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
diff --git a/tag/merge-sort/README.md b/tag/merge-sort/README.md
deleted file mode 100644
index 81df28808..000000000
--- a/tag/merge-sort/README.md
+++ /dev/null
@@ -1,19 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 归并排序
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2031 | [1 比 0 多的子数组个数](../../problems/count-subarrays-with-more-ones-than-zeros) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 1649 | [通过指令创建有序数组](../../problems/create-sorted-array-through-instructions) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 912 | [排序数组](../../problems/sort-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数排序](../counting-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 493 | [翻转对](../../problems/reverse-pairs) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 327 | [区间和的个数](../../problems/count-of-range-sum) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 315 | [计算右侧小于当前元素的个数](../../problems/count-of-smaller-numbers-after-self) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 148 | [排序链表](../../problems/sort-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)] [[分治](../divide-and-conquer/README.md)] [[排序](../sorting/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 23 | [合并K个升序链表](../../problems/merge-k-sorted-lists) | [[链表](../linked-list/README.md)] [[分治](../divide-and-conquer/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
diff --git a/tag/minimax/README.md b/tag/minimax/README.md
deleted file mode 100644
index 2b0194212..000000000
--- a/tag/minimax/README.md
+++ /dev/null
@@ -1,11 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 极小化极大
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
diff --git a/tag/minimum-spanning-tree/README.md b/tag/minimum-spanning-tree/README.md
deleted file mode 100644
index 8fcbd0882..000000000
--- a/tag/minimum-spanning-tree/README.md
+++ /dev/null
@@ -1,16 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 最小生成树
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1724 | [检查边长度限制的路径是否存在 II](../../problems/checking-existence-of-edge-length-limited-paths-ii) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)]  | Hard |
-| 1584 | [连接所有点的最小费用](../../problems/min-cost-to-connect-all-points) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)]  | Medium |
-| 1489 | [找到最小生成树里的关键边和伪关键边](../../problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)] [[排序](../sorting/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
-| 1168 | [水资源分配优化](../../problems/optimize-water-distribution-in-a-village) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)]  | Hard |
-| 1135 | [最低成本联通所有城市](../../problems/connecting-cities-with-minimum-cost) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
diff --git a/tag/monotonic-queue/README.md b/tag/monotonic-queue/README.md
deleted file mode 100644
index 79f7a4226..000000000
--- a/tag/monotonic-queue/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 单调队列
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2071 | [你可以安排的最多任务数目](../../problems/maximum-number-of-tasks-you-can-assign) | [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Hard |
-| 1696 | [跳跃游戏 VI](../../problems/jump-game-vi) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1687 | [从仓库到码头运输箱子](../../problems/delivering-boxes-from-storage-to-ports) | [[线段树](../segment-tree/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1499 | [满足不等式的最大值](../../problems/max-value-of-equation) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1438 | [绝对差不超过限制的最长连续子数组](../../problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1425 | [带限制的子序列和](../../problems/constrained-subsequence-sum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 918 | [环形子数组的最大和](../../problems/maximum-sum-circular-subarray) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Medium |
-| 862 | [和至少为 K 的最短子数组](../../problems/shortest-subarray-with-sum-at-least-k) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 239 | [滑动窗口最大值](../../problems/sliding-window-maximum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
diff --git a/tag/monotonic-stack/README.md b/tag/monotonic-stack/README.md
deleted file mode 100644
index b609198b4..000000000
--- a/tag/monotonic-stack/README.md
+++ /dev/null
@@ -1,51 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 单调栈
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2104 | [子数组范围和](../../problems/sum-of-subarray-ranges) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 2030 | [含特定字母的最小子序列](../../problems/smallest-k-length-subsequence-with-occurrences-of-a-letter) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1996 | [游戏中弱角色的数量](../../problems/the-number-of-weak-characters-in-the-game) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1950 | [所有子数组最小值中的最大值](../../problems/maximum-of-minimum-values-in-all-subarrays) 🔒 | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1944 | [队列中可以看到的人数](../../problems/number-of-visible-people-in-a-queue) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1856 | [子数组最小乘积的最大值](../../problems/maximum-subarray-min-product) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1793 | [好子数组的最大分数](../../problems/maximum-score-of-a-good-subarray) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1776 | [车队 II](../../problems/car-fleet-ii) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[单调栈](../monotonic-stack/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1762 | [能看到海景的建筑物](../../problems/buildings-with-an-ocean-view) 🔒 | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1673 | [找出最具竞争力的子序列](../../problems/find-the-most-competitive-subsequence) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1574 | [删除最短的子数组使剩余数组有序](../../problems/shortest-subarray-to-be-removed-to-make-array-sorted) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1526 | [形成目标数组的子数组最少增加次数](../../problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1504 | [统计全 1 子矩形](../../problems/count-submatrices-with-all-ones) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1475 | [商品折扣后的最终价格](../../problems/final-prices-with-a-special-discount-in-a-shop) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Easy |
-| 1130 | [叶值的最小代价生成树](../../problems/minimum-cost-tree-from-leaf-values) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1124 | [表现良好的最长时间段](../../problems/longest-well-performing-interval) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1081 | [不同字符的最小子序列](../../problems/smallest-subsequence-of-distinct-characters) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1063 | [有效子数组的数目](../../problems/number-of-valid-subarrays) 🔒 | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1019 | [链表中的下一个更大节点](../../problems/next-greater-node-in-linked-list) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1008 | [前序遍历构造二叉搜索树](../../problems/construct-binary-search-tree-from-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 975 | [奇偶跳](../../problems/odd-even-jump) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 962 | [最大宽度坡](../../problems/maximum-width-ramp) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 907 | [子数组的最小值之和](../../problems/sum-of-subarray-minimums) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 901 | [股票价格跨度](../../problems/online-stock-span) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数据流](../data-stream/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 853 | [车队](../../problems/car-fleet) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 769 | [最多能完成排序的块](../../problems/max-chunks-to-make-sorted) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 768 | [最多能完成排序的块 II](../../problems/max-chunks-to-make-sorted-ii) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 739 | [每日温度](../../problems/daily-temperatures) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 654 | [最大二叉树](../../problems/maximum-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 581 | [最短无序连续子数组](../../problems/shortest-unsorted-continuous-subarray) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 503 | [下一个更大元素 II](../../problems/next-greater-element-ii) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 496 | [下一个更大元素 I](../../problems/next-greater-element-i) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Easy |
-| 456 | [132 模式](../../problems/132-pattern) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 402 | [移掉 K 位数字](../../problems/remove-k-digits) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 321 | [拼接最大数](../../problems/create-maximum-number) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 316 | [去除重复字母](../../problems/remove-duplicate-letters) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 255 | [验证前序遍历序列二叉搜索树](../../problems/verify-preorder-sequence-in-binary-search-tree) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 85 | [最大矩形](../../problems/maximal-rectangle) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 84 | [柱状图中最大的矩形](../../problems/largest-rectangle-in-histogram) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 42 | [接雨水](../../problems/trapping-rain-water) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
diff --git a/tag/number-theory/README.md b/tag/number-theory/README.md
deleted file mode 100644
index 07cf48872..000000000
--- a/tag/number-theory/README.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 数论
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2001 | [可互换矩形的组数](../../problems/number-of-pairs-of-interchangeable-rectangles) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1819 | [序列中不同最大公约数的数目](../../problems/number-of-different-subsequences-gcds) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1799 | [N 次操作后的最大分数和](../../problems/maximize-score-after-n-operations) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1447 | [最简分数](../../problems/simplified-fractions) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1250 | [检查「好数组」](../../problems/check-if-it-is-a-good-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[数论](../number-theory/README.md)]  | Hard |
-| 1201 | [丑数 III](../../problems/ugly-number-iii) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 914 | [卡牌分组](../../problems/x-of-a-kind-in-a-deck-of-cards) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[计数](../counting/README.md)] [[数论](../number-theory/README.md)]  | Easy |
-| 258 | [各位相加](../../problems/add-digits) | [[数学](../math/README.md)] [[数论](../number-theory/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 204 | [计数质数](../../problems/count-primes) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[枚举](../enumeration/README.md)] [[数论](../number-theory/README.md)]  | Medium |
diff --git a/tag/oop/README.md b/tag/oop/README.md
deleted file mode 100644
index 4920fb050..000000000
--- a/tag/oop/README.md
+++ /dev/null
@@ -1,11 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > OOP
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
diff --git a/tag/ordered-map/README.md b/tag/ordered-map/README.md
deleted file mode 100644
index bce1a6995..000000000
--- a/tag/ordered-map/README.md
+++ /dev/null
@@ -1,11 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > Ordered Map
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
diff --git a/tag/ordered-set/README.md b/tag/ordered-set/README.md
deleted file mode 100644
index 45db4a2aa..000000000
--- a/tag/ordered-set/README.md
+++ /dev/null
@@ -1,50 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 有序集合
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2158 | [Amount of New Area Painted Each Day](../../problems/amount-of-new-area-painted-each-day) 🔒 | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2102 | [序列顺序查询](../../problems/sequentially-ordinal-rank-tracker) | [[设计](../design/README.md)] [[数据流](../data-stream/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 2035 | [将数组分成两个数组并最小化数组和的差](../../problems/partition-array-into-two-arrays-to-minimize-sum-difference) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2034 | [股票价格波动](../../problems/stock-price-fluctuation) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2031 | [1 比 0 多的子数组个数](../../problems/count-subarrays-with-more-ones-than-zeros) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 2021 | [街上最亮的位置](../../problems/brightest-position-on-street) 🔒 | [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1942 | [最小未被占据椅子的编号](../../problems/the-number-of-the-smallest-unoccupied-chair) | [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1912 | [设计电影租借系统](../../problems/design-movie-rental-system) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1902 | [给定二叉搜索树的插入顺序求深度](../../problems/depth-of-bst-given-insertion-order) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1825 | [求出 MK 平均值](../../problems/finding-mk-average) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1818 | [绝对差值和](../../problems/minimum-absolute-sum-difference) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1756 | [设计最近使用（MRU）队列](../../problems/design-most-recently-used-queue) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1675 | [数组的最小偏移量](../../problems/minimize-deviation-in-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1649 | [通过指令创建有序数组](../../problems/create-sorted-array-through-instructions) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 1606 | [找到处理最多请求的服务器](../../problems/find-servers-that-handled-most-number-of-requests) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1438 | [绝对差不超过限制的最长连续子数组](../../problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1418 | [点菜展示表](../../problems/display-table-of-food-orders-in-a-restaurant) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1348 | [推文计数](../../problems/tweet-counts-per-frequency) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 975 | [奇偶跳](../../problems/odd-even-jump) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 895 | [最大频率栈](../../problems/maximum-frequency-stack) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 855 | [考场就座](../../problems/exam-room) | [[设计](../design/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 850 | [矩形面积 II](../../problems/rectangle-area-ii) | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)]  | Hard |
-| 732 | [我的日程安排表 III](../../problems/my-calendar-iii) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 731 | [我的日程安排表 II](../../problems/my-calendar-ii) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 729 | [我的日程安排表 I](../../problems/my-calendar-i) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 716 | [最大栈](../../problems/max-stack) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)] [[有序集合](../ordered-set/README.md)]  | Easy |
-| 715 | [Range 模块](../../problems/range-module) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 699 | [掉落的方块](../../problems/falling-squares) | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 683 | [K 个关闭的灯泡](../../problems/k-empty-slots) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 635 | [设计日志存储系统](../../problems/design-log-storage-system) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 497 | [非重叠矩形中的随机点](../../problems/random-point-in-non-overlapping-rectangles) | [[水塘抽样](../reservoir-sampling/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 493 | [翻转对](../../problems/reverse-pairs) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 456 | [132 模式](../../problems/132-pattern) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 363 | [矩形区域不超过 K 的最大数值和](../../problems/max-sum-of-rectangle-no-larger-than-k) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 352 | [将数据流变为多个不相交区间](../../problems/data-stream-as-disjoint-intervals) | [[设计](../design/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 327 | [区间和的个数](../../problems/count-of-range-sum) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 315 | [计算右侧小于当前元素的个数](../../problems/count-of-smaller-numbers-after-self) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 220 | [存在重复元素 III](../../problems/contains-duplicate-iii) | [[数组](../array/README.md)] [[桶排序](../bucket-sort/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 218 | [天际线问题](../../problems/the-skyline-problem) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
diff --git a/tag/prefix-sum/README.md b/tag/prefix-sum/README.md
deleted file mode 100644
index 07ca36a90..000000000
--- a/tag/prefix-sum/README.md
+++ /dev/null
@@ -1,86 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 前缀和
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2171 | [拿出最少数目的魔法豆](../../problems/removing-minimum-number-of-magic-beans) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2145 | [统计隐藏数组数目](../../problems/count-the-hidden-sequences) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2132 | [用邮票贴满网格图](../../problems/stamping-the-grid) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 2121 | [相同元素的间隔之和](../../problems/intervals-between-identical-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2106 | [摘水果](../../problems/maximum-fruits-harvested-after-at-most-k-steps) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 2100 | [适合打劫银行的日子](../../problems/find-good-days-to-rob-the-bank) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2083 | [求以相同字母开头和结尾的子串总数](../../problems/substrings-that-begin-and-end-with-the-same-letter) 🔒 | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2067 | [Number of Equal Count Substrings](../../problems/number-of-equal-count-substrings) 🔒 | [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2055 | [蜡烛之间的盘子](../../problems/plates-between-candles) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2025 | [分割数组的最多方案数](../../problems/maximum-number-of-ways-to-partition-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 2024 | [考试的最大困扰度](../../problems/maximize-the-confusion-of-an-exam) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2021 | [街上最亮的位置](../../problems/brightest-position-on-street) 🔒 | [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2017 | [网格游戏](../../problems/grid-game) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1991 | [找到数组的中间位置](../../problems/find-the-middle-index-in-array) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1943 | [描述绘画结果](../../problems/describe-the-painting) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1930 | [长度为 3 的不同回文子序列](../../problems/unique-length-3-palindromic-subsequences) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1915 | [最美子字符串的数目](../../problems/number-of-wonderful-substrings) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1895 | [最大的幻方](../../problems/largest-magic-square) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1894 | [找到需要补充粉笔的学生编号](../../problems/find-the-student-that-will-replace-the-chalk) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1893 | [检查是否区域内所有整数都被覆盖](../../problems/check-if-all-the-integers-in-a-range-are-covered) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1889 | [装包裹的最小浪费空间](../../problems/minimum-space-wasted-from-packaging) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1878 | [矩阵中最大的三个菱形和](../../problems/get-biggest-three-rhombus-sums-in-a-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1872 | [石子游戏 VIII](../../problems/stone-game-viii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1871 | [跳跃游戏 VII](../../problems/jump-game-vii) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1862 | [向下取整数对和](../../problems/sum-of-floored-pairs) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1856 | [子数组最小乘积的最大值](../../problems/maximum-subarray-min-product) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1838 | [最高频元素的频数](../../problems/frequency-of-the-most-frequent-element) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1829 | [每个查询的最大异或值](../../problems/maximum-xor-for-each-query) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1788 | [最大化花园的美观度](../../problems/maximize-the-beauty-of-the-garden) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1744 | [你能在你最喜欢的那天吃到你最喜欢的糖果吗？](../../problems/can-you-eat-your-favorite-candy-on-your-favorite-day) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1738 | [找出第 K 大的异或坐标值](../../problems/find-kth-largest-xor-coordinate-value) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[快速选择](../quickselect/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1737 | [满足三条件之一需改变的最少字符数](../../problems/change-minimum-characters-to-satisfy-one-of-three-conditions) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1732 | [找到最高海拔](../../problems/find-the-highest-altitude) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1712 | [将数组分成三个子数组的方案数](../../problems/ways-to-split-array-into-three-subarrays) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1703 | [得到连续 K 个 1 的最少相邻交换次数](../../problems/minimum-adjacent-swaps-for-k-consecutive-ones) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 1685 | [有序数组中差绝对值之和](../../problems/sum-of-absolute-differences-in-a-sorted-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1674 | [使数组互补的最少操作次数](../../problems/minimum-moves-to-make-array-complementary) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1658 | [将 x 减到 0 的最小操作数](../../problems/minimum-operations-to-reduce-x-to-zero) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1590 | [使数组和能被 P 整除](../../problems/make-sum-divisible-by-p) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1589 | [所有排列中的最大和](../../problems/maximum-sum-obtained-of-any-permutation) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1588 | [所有奇数长度子数组的和](../../problems/sum-of-all-odd-length-subarrays) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1546 | [和为目标值且不重叠的非空子数组的最大数目](../../problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1524 | [和为奇数的子数组数目](../../problems/number-of-sub-arrays-with-odd-sum) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1480 | [一维数组的动态和](../../problems/running-sum-of-1d-array) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1442 | [形成两个异或相等数组的三元组数目](../../problems/count-triplets-that-can-form-two-arrays-of-equal-xor) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1423 | [可获得的最大点数](../../problems/maximum-points-you-can-obtain-from-cards) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1413 | [逐步求和得到正数的最小值](../../problems/minimum-value-to-get-positive-step-by-step-sum) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 1371 | [每个元音包含偶数次的最长子字符串](../../problems/find-the-longest-substring-containing-vowels-in-even-counts) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1314 | [矩阵区域和](../../problems/matrix-block-sum) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1310 | [子数组异或查询](../../problems/xor-queries-of-a-subarray) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1292 | [元素和小于等于阈值的正方形的最大边长](../../problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1208 | [尽可能使字符串相等](../../problems/get-equal-substrings-within-budget) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1177 | [构建回文串检测](../../problems/can-make-palindrome-from-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1124 | [表现良好的最长时间段](../../problems/longest-well-performing-interval) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1109 | [航班预订统计](../../problems/corporate-flight-bookings) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1094 | [拼车](../../problems/car-pooling) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1074 | [元素和为目标值的子矩阵数量](../../problems/number-of-submatrices-that-sum-to-target) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 1004 | [最大连续1的个数 III](../../problems/max-consecutive-ones-iii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 995 | [K 连续位的最小翻转次数](../../problems/minimum-number-of-k-consecutive-bit-flips) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 974 | [和可被 K 整除的子数组](../../problems/subarray-sums-divisible-by-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 930 | [和相同的二元子数组](../../problems/binary-subarrays-with-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 862 | [和至少为 K 的最短子数组](../../problems/shortest-subarray-with-sum-at-least-k) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 798 | [得分最高的最小轮调](../../problems/smallest-rotation-with-highest-score) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 724 | [寻找数组的中心下标](../../problems/find-pivot-index) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 560 | [和为 K 的子数组](../../problems/subarray-sum-equals-k) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 548 | [将数组分割成和相等的子数组](../../problems/split-array-with-equal-sum) 🔒 | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Hard |
-| 528 | [按权重随机选择](../../problems/random-pick-with-weight) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 525 | [连续数组](../../problems/contiguous-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 523 | [连续的子数组和](../../problems/continuous-subarray-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 497 | [非重叠矩形中的随机点](../../problems/random-point-in-non-overlapping-rectangles) | [[水塘抽样](../reservoir-sampling/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 370 | [区间加法](../../problems/range-addition) 🔒 | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 304 | [二维区域和检索 - 矩阵不可变](../../problems/range-sum-query-2d-immutable) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 303 | [区域和检索 - 数组不可变](../../problems/range-sum-query-immutable) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Easy |
-| 238 | [除自身以外数组的乘积](../../problems/product-of-array-except-self) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 209 | [长度最小的子数组](../../problems/minimum-size-subarray-sum) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
diff --git a/tag/probability-and-statistics/README.md b/tag/probability-and-statistics/README.md
deleted file mode 100644
index e96a3f6ad..000000000
--- a/tag/probability-and-statistics/README.md
+++ /dev/null
@@ -1,18 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 概率与统计
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1467 | [两个盒子中球的颜色数相同的概率](../../problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[组合数学](../combinatorics/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Hard |
-| 1230 | [抛掷硬币](../../problems/toss-strange-coins) 🔒 | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 1227 | [飞机座位分配概率](../../problems/airplane-seat-assignment-probability) | [[脑筋急转弯](../brainteaser/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 1093 | [大样本统计](../../problems/statistics-from-a-large-sample) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 837 | [新 21 点](../../problems/new-21-game) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 808 | [分汤](../../problems/soup-servings) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 470 | [用 Rand7() 实现 Rand10()](../../problems/implement-rand10-using-rand7) | [[数学](../math/README.md)] [[拒绝采样](../rejection-sampling/README.md)] [[概率与统计](../probability-and-statistics/README.md)] [[随机化](../randomized/README.md)]  | Medium |
diff --git a/tag/queue/README.md b/tag/queue/README.md
deleted file mode 100644
index 2db4c7d3d..000000000
--- a/tag/queue/README.md
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 队列
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2073 | [买票需要的时间](../../problems/time-needed-to-buy-tickets) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2071 | [你可以安排的最多任务数目](../../problems/maximum-number-of-tasks-you-can-assign) | [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Hard |
-| 1825 | [求出 MK 平均值](../../problems/finding-mk-average) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[有序集合](../ordered-set/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1823 | [找出游戏的获胜者](../../problems/find-the-winner-of-the-circular-game) | [[递归](../recursion/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1700 | [无法吃午餐的学生数量](../../problems/number-of-students-unable-to-eat-lunch) | [[栈](../stack/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1696 | [跳跃游戏 VI](../../problems/jump-game-vi) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1687 | [从仓库到码头运输箱子](../../problems/delivering-boxes-from-storage-to-ports) | [[线段树](../segment-tree/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1670 | [设计前中后队列](../../problems/design-front-middle-back-queue) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1499 | [满足不等式的最大值](../../problems/max-value-of-equation) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1438 | [绝对差不超过限制的最长连续子数组](../../problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1429 | [第一个唯一数字](../../problems/first-unique-number) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 1425 | [带限制的子序列和](../../problems/constrained-subsequence-sum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1352 | [最后 K 个数的乘积](../../problems/product-of-the-last-k-numbers) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[数据流](../data-stream/README.md)]  | Medium |
-| 950 | [按递增顺序显示卡牌](../../problems/reveal-cards-in-increasing-order) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 936 | [戳印序列](../../problems/stamping-the-sequence) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 933 | [最近的请求次数](../../problems/number-of-recent-calls) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 918 | [环形子数组的最大和](../../problems/maximum-sum-circular-subarray) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Medium |
-| 862 | [和至少为 K 的最短子数组](../../problems/shortest-subarray-with-sum-at-least-k) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 649 | [Dota2 参议院](../../problems/dota2-senate) | [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 641 | [设计循环双端队列](../../problems/design-circular-deque) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 622 | [设计循环队列](../../problems/design-circular-queue) | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 387 | [字符串中的第一个唯一字符](../../problems/first-unique-character-in-a-string) | [[队列](../queue/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 379 | [电话目录管理系统](../../problems/design-phone-directory) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 362 | [敲击计数器](../../problems/design-hit-counter) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 353 | [贪吃蛇](../../problems/design-snake-game) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 346 | [数据流中的移动平均值](../../problems/moving-average-from-data-stream) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 341 | [扁平化嵌套列表迭代器](../../problems/flatten-nested-list-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 281 | [锯齿迭代器](../../problems/zigzag-iterator) 🔒 | [[设计](../design/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 239 | [滑动窗口最大值](../../problems/sliding-window-maximum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 232 | [用栈实现队列](../../problems/implement-queue-using-stacks) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)]  | Easy |
-| 225 | [用队列实现栈](../../problems/implement-stack-using-queues) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)]  | Easy |
diff --git a/tag/quickselect/README.md b/tag/quickselect/README.md
deleted file mode 100644
index 758e2f111..000000000
--- a/tag/quickselect/README.md
+++ /dev/null
@@ -1,17 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 快速选择
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1985 | [找出数组中的第 K 大整数](../../problems/find-the-kth-largest-integer-in-the-array) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1738 | [找出第 K 大的异或坐标值](../../problems/find-kth-largest-xor-coordinate-value) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[快速选择](../quickselect/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 973 | [最接近原点的 K 个点](../../problems/k-closest-points-to-origin) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 347 | [前 K 个高频元素](../../problems/top-k-frequent-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 324 | [摆动排序 II](../../problems/wiggle-sort-ii) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 215 | [数组中的第K个最大元素](../../problems/kth-largest-element-in-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
diff --git a/tag/radix-sort/README.md b/tag/radix-sort/README.md
deleted file mode 100644
index 859147d07..000000000
--- a/tag/radix-sort/README.md
+++ /dev/null
@@ -1,13 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 基数排序
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 912 | [排序数组](../../problems/sort-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数排序](../counting-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 164 | [最大间距](../../problems/maximum-gap) | [[数组](../array/README.md)] [[桶排序](../bucket-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)]  | Hard |
diff --git a/tag/random/README.md b/tag/random/README.md
deleted file mode 100644
index 66c8e79c0..000000000
--- a/tag/random/README.md
+++ /dev/null
@@ -1,11 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > Random
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
diff --git a/tag/randomized/README.md b/tag/randomized/README.md
deleted file mode 100644
index c991c6b5f..000000000
--- a/tag/randomized/README.md
+++ /dev/null
@@ -1,23 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 随机化
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1515 | [服务中心的最佳位置](../../problems/best-position-for-a-service-centre) | [[几何](../geometry/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 710 | [黑名单中的随机数](../../problems/random-pick-with-blacklist) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 528 | [按权重随机选择](../../problems/random-pick-with-weight) | [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 519 | [随机翻转矩阵](../../problems/random-flip-matrix) | [[水塘抽样](../reservoir-sampling/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 497 | [非重叠矩形中的随机点](../../problems/random-point-in-non-overlapping-rectangles) | [[水塘抽样](../reservoir-sampling/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 478 | [在圆内随机生成点](../../problems/generate-random-point-in-a-circle) | [[几何](../geometry/README.md)] [[数学](../math/README.md)] [[拒绝采样](../rejection-sampling/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 470 | [用 Rand7() 实现 Rand10()](../../problems/implement-rand10-using-rand7) | [[数学](../math/README.md)] [[拒绝采样](../rejection-sampling/README.md)] [[概率与统计](../probability-and-statistics/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 398 | [随机数索引](../../problems/random-pick-index) | [[水塘抽样](../reservoir-sampling/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 384 | [打乱数组](../../problems/shuffle-an-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 382 | [链表随机节点](../../problems/linked-list-random-node) | [[水塘抽样](../reservoir-sampling/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 381 | [O(1) 时间插入、删除和获取随机元素 - 允许重复](../../problems/insert-delete-getrandom-o1-duplicates-allowed) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 380 | [O(1) 时间插入、删除和获取随机元素](../../problems/insert-delete-getrandom-o1) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
diff --git a/tag/recursion/README.md b/tag/recursion/README.md
deleted file mode 100644
index c6113caa1..000000000
--- a/tag/recursion/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 递归
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1969 | [数组元素的最小非零乘积](../../problems/minimum-non-zero-product-of-the-array-elements) | [[贪心](../greedy/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1922 | [统计好数字的数目](../../problems/count-good-numbers) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 1823 | [找出游戏的获胜者](../../problems/find-the-winner-of-the-circular-game) | [[递归](../recursion/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1808 | [好因子的最大数目](../../problems/maximize-number-of-nice-divisors) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1545 | [找出第 N 个二进制字符串中的第 K 位](../../problems/find-kth-bit-in-nth-binary-string) | [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1265 | [逆序打印不可变链表](../../problems/print-immutable-linked-list-in-reverse) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1106 | [解析布尔表达式](../../problems/parsing-a-boolean-expression) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 894 | [所有可能的满二叉树](../../problems/all-possible-full-binary-trees) | [[树](../tree/README.md)] [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 779 | [第K个语法符号](../../problems/k-th-symbol-in-grammar) | [[位运算](../bit-manipulation/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 776 | [拆分二叉搜索树](../../problems/split-bst) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 772 | [基本计算器 III](../../problems/basic-calculator-iii) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 770 | [基本计算器 IV](../../problems/basic-calculator-iv) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 761 | [特殊的二进制序列](../../problems/special-binary-string) | [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 736 | [Lisp 语法解析](../../problems/parse-lisp-expression) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 544 | [输出比赛匹配对](../../problems/output-contest-matches) 🔒 | [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 509 | [斐波那契数](../../problems/fibonacci-number) | [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 486 | [预测赢家](../../problems/predict-the-winner) | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 439 | [三元表达式解析器](../../problems/ternary-expression-parser) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 394 | [字符串解码](../../problems/decode-string) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 344 | [反转字符串](../../problems/reverse-string) | [[递归](../recursion/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 342 | [4的幂](../../problems/power-of-four) | [[位运算](../bit-manipulation/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Easy |
-| 326 | [3 的幂](../../problems/power-of-three) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Easy |
-| 273 | [整数转换英文表示](../../problems/integer-to-english-words) | [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 255 | [验证前序遍历序列二叉搜索树](../../problems/verify-preorder-sequence-in-binary-search-tree) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 248 | [中心对称数 III](../../problems/strobogrammatic-number-iii) 🔒 | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 247 | [中心对称数 II](../../problems/strobogrammatic-number-ii) 🔒 | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 241 | [为运算表达式设计优先级](../../problems/different-ways-to-add-parentheses) | [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 234 | [回文链表](../../problems/palindrome-linked-list) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 233 | [数字 1 的个数](../../problems/number-of-digit-one) | [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 231 | [2 的幂](../../problems/power-of-two) | [[位运算](../bit-manipulation/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Easy |
-| 224 | [基本计算器](../../problems/basic-calculator) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 206 | [反转链表](../../problems/reverse-linked-list) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Easy |
-| 203 | [移除链表元素](../../problems/remove-linked-list-elements) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Easy |
-| 143 | [重排链表](../../problems/reorder-list) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 60 | [排列序列](../../problems/permutation-sequence) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Hard |
-| 50 | [Pow(x, n)](../../problems/powx-n) | [[递归](../recursion/README.md)] [[数学](../math/README.md)]  | Medium |
-| 44 | [通配符匹配](../../problems/wildcard-matching) | [[贪心](../greedy/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 25 | [K 个一组翻转链表](../../problems/reverse-nodes-in-k-group) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Hard |
-| 24 | [两两交换链表中的节点](../../problems/swap-nodes-in-pairs) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Medium |
-| 21 | [合并两个有序链表](../../problems/merge-two-sorted-lists) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)]  | Easy |
-| 10 | [正则表达式匹配](../../problems/regular-expression-matching) | [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2 | [两数相加](../../problems/add-two-numbers) | [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Medium |
diff --git a/tag/rejection-sampling/README.md b/tag/rejection-sampling/README.md
deleted file mode 100644
index 7dda478a0..000000000
--- a/tag/rejection-sampling/README.md
+++ /dev/null
@@ -1,13 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 拒绝采样
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 478 | [在圆内随机生成点](../../problems/generate-random-point-in-a-circle) | [[几何](../geometry/README.md)] [[数学](../math/README.md)] [[拒绝采样](../rejection-sampling/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 470 | [用 Rand7() 实现 Rand10()](../../problems/implement-rand10-using-rand7) | [[数学](../math/README.md)] [[拒绝采样](../rejection-sampling/README.md)] [[概率与统计](../probability-and-statistics/README.md)] [[随机化](../randomized/README.md)]  | Medium |
diff --git a/tag/reservoir-sampling/README.md b/tag/reservoir-sampling/README.md
deleted file mode 100644
index 719ab9946..000000000
--- a/tag/reservoir-sampling/README.md
+++ /dev/null
@@ -1,15 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 水塘抽样
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 519 | [随机翻转矩阵](../../problems/random-flip-matrix) | [[水塘抽样](../reservoir-sampling/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 497 | [非重叠矩形中的随机点](../../problems/random-point-in-non-overlapping-rectangles) | [[水塘抽样](../reservoir-sampling/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[前缀和](../prefix-sum/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 398 | [随机数索引](../../problems/random-pick-index) | [[水塘抽样](../reservoir-sampling/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
-| 382 | [链表随机节点](../../problems/linked-list-random-node) | [[水塘抽样](../reservoir-sampling/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)] [[随机化](../randomized/README.md)]  | Medium |
diff --git a/tag/rolling-hash/README.md b/tag/rolling-hash/README.md
deleted file mode 100644
index 929c4e240..000000000
--- a/tag/rolling-hash/README.md
+++ /dev/null
@@ -1,26 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 滚动哈希
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2168 | [Unique Substrings With Equal Digit Frequency](../../problems/unique-substrings-with-equal-digit-frequency) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 2156 | [查找给定哈希值的子串](../../problems/find-substring-with-given-hash-value) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1960 | [两个回文子字符串长度的最大乘积](../../problems/maximum-product-of-the-length-of-two-palindromic-substrings) | [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1923 | [最长公共子路径](../../problems/longest-common-subpath) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1698 | [字符串的不同子字符串个数](../../problems/number-of-distinct-substrings-in-a-string) 🔒 | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1554 | [只有一个不同字符的字符串](../../problems/strings-differ-by-one-character) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1461 | [检查一个字符串是否包含所有长度为 K 的二进制子串](../../problems/check-if-a-string-contains-all-binary-codes-of-size-k) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1392 | [最长快乐前缀](../../problems/longest-happy-prefix) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1316 | [不同的循环子字符串](../../problems/distinct-echo-substrings) | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1147 | [段式回文](../../problems/longest-chunked-palindrome-decomposition) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1062 | [最长重复子串](../../problems/longest-repeating-substring) 🔒 | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1044 | [最长重复子串](../../problems/longest-duplicate-substring) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 718 | [最长重复子数组](../../problems/maximum-length-of-repeated-subarray) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 214 | [最短回文串](../../problems/shortest-palindrome) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 187 | [重复的DNA序列](../../problems/repeated-dna-sequences) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
diff --git a/tag/segment-tree/README.md b/tag/segment-tree/README.md
deleted file mode 100644
index d15fa7dfa..000000000
--- a/tag/segment-tree/README.md
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 线段树
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2158 | [Amount of New Area Painted Each Day](../../problems/amount-of-new-area-painted-each-day) 🔒 | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2080 | [区间内查询数字的频率](../../problems/range-frequency-queries) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 2031 | [1 比 0 多的子数组个数](../../problems/count-subarrays-with-more-ones-than-zeros) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 1687 | [从仓库到码头运输箱子](../../problems/delivering-boxes-from-storage-to-ports) | [[线段树](../segment-tree/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1649 | [通过指令创建有序数组](../../problems/create-sorted-array-through-instructions) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 1622 | [奇妙序列](../../problems/fancy-sequence) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1521 | [找到最接近目标值的函数值](../../problems/find-a-value-of-a-mysterious-function-closest-to-target) | [[位运算](../bit-manipulation/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1505 | [最多 K 次交换相邻数位后得到的最小整数](../../problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits) | [[贪心](../greedy/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1157 | [子数组中占绝大多数的元素](../../problems/online-majority-element-in-subarray) | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 850 | [矩形面积 II](../../problems/rectangle-area-ii) | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)]  | Hard |
-| 732 | [我的日程安排表 III](../../problems/my-calendar-iii) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 731 | [我的日程安排表 II](../../problems/my-calendar-ii) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 729 | [我的日程安排表 I](../../problems/my-calendar-i) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 715 | [Range 模块](../../problems/range-module) | [[设计](../design/README.md)] [[线段树](../segment-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 699 | [掉落的方块](../../problems/falling-squares) | [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 673 | [最长递增子序列的个数](../../problems/number-of-longest-increasing-subsequence) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 493 | [翻转对](../../problems/reverse-pairs) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 327 | [区间和的个数](../../problems/count-of-range-sum) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 315 | [计算右侧小于当前元素的个数](../../problems/count-of-smaller-numbers-after-self) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[归并排序](../merge-sort/README.md)]  | Hard |
-| 308 | [二维区域和检索 - 可变](../../problems/range-sum-query-2d-mutable) 🔒 | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 307 | [区域和检索 - 数组可修改](../../problems/range-sum-query-mutable) | [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)]  | Medium |
-| 218 | [天际线问题](../../problems/the-skyline-problem) | [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[有序集合](../ordered-set/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
diff --git a/tag/shortest-path/README.md b/tag/shortest-path/README.md
deleted file mode 100644
index 09e0f7c25..000000000
--- a/tag/shortest-path/README.md
+++ /dev/null
@@ -1,24 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 最短路
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2093 | [Minimum Cost to Reach City With Discounts](../../problems/minimum-cost-to-reach-city-with-discounts) 🔒 | [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 2045 | [到达目的地的第二短时间](../../problems/second-minimum-time-to-reach-destination) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)]  | Hard |
-| 1976 | [到达目的地的方案数](../../problems/number-of-ways-to-arrive-at-destination) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 1786 | [从第一个节点出发到最后一个节点的受限路径数](../../problems/number-of-restricted-paths-from-first-to-last-node) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1514 | [概率最大的路径](../../problems/path-with-maximum-probability) | [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1368 | [使网格图至少有一条有效路径的最小代价](../../problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid) | [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1334 | [阈值距离内邻居最少的城市](../../problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance) | [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 882 | [细分图中的可到达结点](../../problems/reachable-nodes-in-subdivided-graph) | [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 787 | [K 站中转内最便宜的航班](../../problems/cheapest-flights-within-k-stops) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 743 | [网络延迟时间](../../problems/network-delay-time) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 505 | [迷宫 II](../../problems/the-maze-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 499 | [迷宫 III](../../problems/the-maze-iii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 399 | [除法求值](../../problems/evaluate-division) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
diff --git a/tag/simulation/README.md b/tag/simulation/README.md
deleted file mode 100644
index 06983fe1f..000000000
--- a/tag/simulation/README.md
+++ /dev/null
@@ -1,96 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 模拟
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2169 | [得到 0 的操作数](../../problems/count-operations-to-obtain-zero) | [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2161 | [根据给定数字划分数组](../../problems/partition-array-according-to-given-pivot) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2154 | [将找到的值乘以 2](../../problems/keep-multiplying-found-values-by-two) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2149 | [按符号重排数组](../../problems/rearrange-array-elements-by-sign) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2138 | [将字符串拆分为若干长度为 k 的组](../../problems/divide-a-string-into-groups-of-size-k) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2120 | [执行所有后缀指令](../../problems/execution-of-all-suffix-instructions-staying-in-a-grid) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2109 | [向字符串添加空格](../../problems/adding-spaces-to-a-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2105 | [给植物浇水 II](../../problems/watering-plants-ii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2075 | [解码斜向换位密码](../../problems/decode-the-slanted-ciphertext) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2073 | [买票需要的时间](../../problems/time-needed-to-buy-tickets) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2069 | [模拟行走机器人 II](../../problems/walking-robot-simulation-ii) | [[设计](../design/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2061 | [扫地机器人清扫过的空间个数](../../problems/number-of-spaces-cleaning-robot-cleaned) 🔒 | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2056 | [棋盘上有效移动组合的数目](../../problems/number-of-valid-move-combinations-on-chessboard) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 2043 | [简易银行系统](../../problems/simple-bank-system) | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2028 | [找出缺失的观测数据](../../problems/find-missing-observations) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2022 | [将一维数组转变成二维数组](../../problems/convert-1d-array-into-2d-array) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2011 | [执行操作后的变量值](../../problems/final-value-of-variable-after-performing-operations) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1945 | [字符串转化后的各位数字之和](../../problems/sum-of-digits-of-string-after-convert) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1920 | [基于排列构建数组](../../problems/build-array-from-permutation) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1914 | [循环轮转矩阵](../../problems/cyclically-rotating-a-grid) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1894 | [找到需要补充粉笔的学生编号](../../problems/find-the-student-that-will-replace-the-chalk) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1860 | [增长的内存泄露](../../problems/incremental-memory-leak) | [[模拟](../simulation/README.md)]  | Medium |
-| 1823 | [找出游戏的获胜者](../../problems/find-the-winner-of-the-circular-game) | [[递归](../recursion/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1806 | [还原排列的最少操作步数](../../problems/minimum-number-of-operations-to-reinitialize-a-permutation) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1801 | [积压订单中的订单总数](../../problems/number-of-orders-in-the-backlog) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1706 | [球会落何处](../../problems/where-will-the-ball-fall) | [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1701 | [平均等待时间](../../problems/average-waiting-time) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1700 | [无法吃午餐的学生数量](../../problems/number-of-students-unable-to-eat-lunch) | [[栈](../stack/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1688 | [比赛中的配对次数](../../problems/count-of-matches-in-tournament) | [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1680 | [连接连续二进制数字](../../problems/concatenation-of-consecutive-binary-numbers) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1646 | [获取生成数组中的最大值](../../problems/get-maximum-in-generated-array) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1603 | [设计停车系统](../../problems/design-parking-system) | [[设计](../design/README.md)] [[计数](../counting/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1599 | [经营摩天轮的最大利润](../../problems/maximum-profit-of-operating-a-centennial-wheel) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1583 | [统计不开心的朋友](../../problems/count-unhappy-friends) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1562 | [查找大小为 M 的最新分组](../../problems/find-latest-group-of-size-m) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1560 | [圆形赛道上经过次数最多的扇区](../../problems/most-visited-sector-in-a-circular-track) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1535 | [找出数组游戏的赢家](../../problems/find-the-winner-of-an-array-game) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1518 | [换酒问题](../../problems/water-bottles) | [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1503 | [所有蚂蚁掉下来前的最后一刻](../../problems/last-moment-before-all-ants-fall-out-of-a-plank) | [[脑筋急转弯](../brainteaser/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1441 | [用栈操作构建数组](../../problems/build-an-array-with-stack-operations) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1409 | [查询带键的排列](../../problems/queries-on-a-permutation-with-key) | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1389 | [按既定顺序创建目标数组](../../problems/create-target-array-in-the-given-order) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1324 | [竖直打印单词](../../problems/print-words-vertically) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1275 | [找出井字棋的获胜者](../../problems/find-winner-on-a-tic-tac-toe-game) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1260 | [二维网格迁移](../../problems/shift-2d-grid) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1252 | [奇数值单元格的数目](../../problems/cells-with-odd-values-in-a-matrix) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1243 | [数组变换](../../problems/array-transformation) 🔒 | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1222 | [可以攻击国王的皇后](../../problems/queens-that-can-attack-the-king) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1103 | [分糖果 II](../../problems/distribute-candies-to-people) | [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1094 | [拼车](../../problems/car-pooling) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1041 | [困于环中的机器人](../../problems/robot-bounded-in-circle) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1006 | [笨阶乘](../../problems/clumsy-factorial) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 999 | [可以被一步捕获的棋子数](../../problems/available-captures-for-rook) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 985 | [查询后的偶数和](../../problems/sum-of-even-numbers-after-queries) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 950 | [按递增顺序显示卡牌](../../problems/reveal-cards-in-increasing-order) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 946 | [验证栈序列](../../problems/validate-stack-sequences) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 885 | [螺旋矩阵 III](../../problems/spiral-matrix-iii) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 874 | [模拟行走机器人](../../problems/walking-robot-simulation) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 867 | [转置矩阵](../../problems/transpose-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 844 | [比较含退格的字符串](../../problems/backspace-string-compare) | [[栈](../stack/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 832 | [翻转图像](../../problems/flipping-an-image) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 755 | [倒水](../../problems/pour-water) 🔒 | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 749 | [隔离病毒](../../problems/contain-virus) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 723 | [粉碎糖果](../../problems/candy-crush) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 682 | [棒球比赛](../../problems/baseball-game) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 657 | [机器人能否返回原点](../../problems/robot-return-to-origin) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 640 | [求解方程](../../problems/solve-the-equation) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 592 | [分数加减运算](../../problems/fraction-addition-and-subtraction) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 566 | [重塑矩阵](../../problems/reshape-the-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 544 | [输出比赛匹配对](../../problems/output-contest-matches) 🔒 | [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 537 | [复数乘法](../../problems/complex-number-multiplication) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 498 | [对角线遍历](../../problems/diagonal-traverse) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 495 | [提莫攻击](../../problems/teemo-attacking) | [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 418 | [屏幕可显示句子的数量](../../problems/sentence-screen-fitting) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 415 | [字符串相加](../../problems/add-strings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 412 | [Fizz Buzz](../../problems/fizz-buzz) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 289 | [生命游戏](../../problems/game-of-life) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 258 | [各位相加](../../problems/add-digits) | [[数学](../math/README.md)] [[数论](../number-theory/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 158 | [用 Read4 读取 N 个字符 II](../../problems/read-n-characters-given-read4-ii-call-multiple-times) 🔒 | [[字符串](../string/README.md)] [[交互](../interactive/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 157 | [用 Read4 读取 N 个字符](../../problems/read-n-characters-given-read4) 🔒 | [[字符串](../string/README.md)] [[交互](../interactive/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 68 | [文本左右对齐](../../problems/text-justification) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 67 | [二进制求和](../../problems/add-binary) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 59 | [螺旋矩阵 II](../../problems/spiral-matrix-ii) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 54 | [螺旋矩阵](../../problems/spiral-matrix) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 43 | [字符串相乘](../../problems/multiply-strings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
diff --git a/tag/sliding-window/README.md b/tag/sliding-window/README.md
deleted file mode 100644
index c77329490..000000000
--- a/tag/sliding-window/README.md
+++ /dev/null
@@ -1,80 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 滑动窗口
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2156 | [查找给定哈希值的子串](../../problems/find-substring-with-given-hash-value) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 2134 | [最少交换次数来组合所有的 1 II](../../problems/minimum-swaps-to-group-all-1s-together-ii) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2107 | [Number of Unique Flavors After Sharing K Candies](../../problems/number-of-unique-flavors-after-sharing-k-candies) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2106 | [摘水果](../../problems/maximum-fruits-harvested-after-at-most-k-steps) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 2090 | [半径为 k 的子数组平均值](../../problems/k-radius-subarray-averages) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2024 | [考试的最大困扰度](../../problems/maximize-the-confusion-of-an-exam) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1984 | [学生分数的最小差值](../../problems/minimum-difference-between-highest-and-lowest-of-k-scores) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1918 | [第 K 小的子数组和·](../../problems/kth-smallest-subarray-sum) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1876 | [长度为三且各字符不同的子字符串](../../problems/substrings-of-size-three-with-distinct-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1852 | [每个子数组的数字种类数](../../problems/distinct-numbers-in-each-subarray) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1839 | [所有元音按顺序排布的最长子字符串](../../problems/longest-substring-of-all-vowels-in-order) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1838 | [最高频元素的频数](../../problems/frequency-of-the-most-frequent-element) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1763 | [最长的美好子字符串](../../problems/longest-nice-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1703 | [得到连续 K 个 1 的最少相邻交换次数](../../problems/minimum-adjacent-swaps-for-k-consecutive-ones) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 1696 | [跳跃游戏 VI](../../problems/jump-game-vi) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1695 | [删除子数组的最大得分](../../problems/maximum-erasure-value) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1658 | [将 x 减到 0 的最小操作数](../../problems/minimum-operations-to-reduce-x-to-zero) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1610 | [可见点的最大数目](../../problems/maximum-number-of-visible-points) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 1499 | [满足不等式的最大值](../../problems/max-value-of-equation) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1493 | [删掉一个元素以后全为 1 的最长子数组](../../problems/longest-subarray-of-1s-after-deleting-one-element) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1477 | [找两个和为目标值且不重叠的子数组](../../problems/find-two-non-overlapping-sub-arrays-each-with-target-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1456 | [定长子串中元音的最大数目](../../problems/maximum-number-of-vowels-in-a-substring-of-given-length) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1438 | [绝对差不超过限制的最长连续子数组](../../problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1425 | [带限制的子序列和](../../problems/constrained-subsequence-sum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1423 | [可获得的最大点数](../../problems/maximum-points-you-can-obtain-from-cards) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1358 | [包含所有三种字符的子字符串数目](../../problems/number-of-substrings-containing-all-three-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1343 | [大小为 K 且平均值大于等于阈值的子数组数目](../../problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1316 | [不同的循环子字符串](../../problems/distinct-echo-substrings) | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1297 | [子串的最大出现次数](../../problems/maximum-number-of-occurrences-of-a-substring) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1248 | [统计「优美子数组」](../../problems/count-number-of-nice-subarrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1234 | [替换子串得到平衡字符串](../../problems/replace-the-substring-for-balanced-string) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1208 | [尽可能使字符串相等](../../problems/get-equal-substrings-within-budget) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1176 | [健身计划评估](../../problems/diet-plan-performance) 🔒 | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1156 | [单字符重复子串的最大长度](../../problems/swap-for-longest-repeated-character-substring) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1151 | [最少交换次数来组合所有的 1](../../problems/minimum-swaps-to-group-all-1s-together) 🔒 | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1100 | [长度为 K 的无重复字符子串](../../problems/find-k-length-substrings-with-no-repeated-characters) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1052 | [爱生气的书店老板](../../problems/grumpy-bookstore-owner) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1044 | [最长重复子串](../../problems/longest-duplicate-substring) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1031 | [两个非重叠子数组的最大和](../../problems/maximum-sum-of-two-non-overlapping-subarrays) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1004 | [最大连续1的个数 III](../../problems/max-consecutive-ones-iii) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 995 | [K 连续位的最小翻转次数](../../problems/minimum-number-of-k-consecutive-bit-flips) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 992 | [K 个不同整数的子数组](../../problems/subarrays-with-k-different-integers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 978 | [最长湍流子数组](../../problems/longest-turbulent-subarray) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 930 | [和相同的二元子数组](../../problems/binary-subarrays-with-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 904 | [水果成篮](../../problems/fruit-into-baskets) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 862 | [和至少为 K 的最短子数组](../../problems/shortest-subarray-with-sum-at-least-k) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 837 | [新 21 点](../../problems/new-21-game) | [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 727 | [最小窗口子序列](../../problems/minimum-window-subsequence) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 718 | [最长重复子数组](../../problems/maximum-length-of-repeated-subarray) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 713 | [乘积小于K的子数组](../../problems/subarray-product-less-than-k) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 683 | [K 个关闭的灯泡](../../problems/k-empty-slots) 🔒 | [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[有序集合](../ordered-set/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 643 | [子数组最大平均数 I](../../problems/maximum-average-subarray-i) | [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 632 | [最小区间](../../problems/smallest-range-covering-elements-from-k-lists) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 567 | [字符串的排列](../../problems/permutation-in-string) | [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 487 | [最大连续1的个数 II](../../problems/max-consecutive-ones-ii) 🔒 | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 480 | [滑动窗口中位数](../../problems/sliding-window-median) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 438 | [找到字符串中所有字母异位词](../../problems/find-all-anagrams-in-a-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 424 | [替换后的最长重复字符](../../problems/longest-repeating-character-replacement) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 395 | [至少有 K 个重复字符的最长子串](../../problems/longest-substring-with-at-least-k-repeating-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 340 | [至多包含 K 个不同字符的最长子串](../../problems/longest-substring-with-at-most-k-distinct-characters) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 239 | [滑动窗口最大值](../../problems/sliding-window-maximum) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[单调队列](../monotonic-queue/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 220 | [存在重复元素 III](../../problems/contains-duplicate-iii) | [[数组](../array/README.md)] [[桶排序](../bucket-sort/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 219 | [存在重复元素 II](../../problems/contains-duplicate-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 209 | [长度最小的子数组](../../problems/minimum-size-subarray-sum) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 187 | [重复的DNA序列](../../problems/repeated-dna-sequences) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 159 | [至多包含两个不同字符的最长子串](../../problems/longest-substring-with-at-most-two-distinct-characters) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 76 | [最小覆盖子串](../../problems/minimum-window-substring) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 30 | [串联所有单词的子串](../../problems/substring-with-concatenation-of-all-words) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 3 | [无重复字符的最长子串](../../problems/longest-substring-without-repeating-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
diff --git a/tag/sort/README.md b/tag/sort/README.md
deleted file mode 100644
index 420418d41..000000000
--- a/tag/sort/README.md
+++ /dev/null
@@ -1,11 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 排序
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
diff --git a/tag/sorting/README.md b/tag/sorting/README.md
deleted file mode 100644
index 0ac1e9083..000000000
--- a/tag/sorting/README.md
+++ /dev/null
@@ -1,244 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 排序
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2171 | [拿出最少数目的魔法豆](../../problems/removing-minimum-number-of-magic-beans) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2165 | [重排数字的最小值](../../problems/smallest-value-of-the-rearranged-number) | [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2164 | [对奇偶下标分别排序](../../problems/sort-even-and-odd-indices-independently) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2160 | [拆分数位后四位数字的最小和](../../problems/minimum-sum-of-four-digit-number-after-splitting-digits) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2154 | [将找到的值乘以 2](../../problems/keep-multiplying-found-values-by-two) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2148 | [元素计数](../../problems/count-elements-with-strictly-smaller-and-greater-elements) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2146 | [价格范围内最高排名的 K 样物品](../../problems/k-highest-ranked-items-within-a-price-range) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2144 | [打折购买糖果的最小开销](../../problems/minimum-cost-of-buying-candies-with-discount) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2141 | [同时运行 N 台电脑的最长时间](../../problems/maximum-running-time-of-n-computers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2136 | [全部开花的最早一天](../../problems/earliest-possible-day-of-full-bloom) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2135 | [统计追加字母可以获得的单词数](../../problems/count-words-obtained-after-adding-a-letter) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2126 | [摧毁小行星](../../problems/destroying-asteroids) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2122 | [还原原数组](../../problems/recover-the-original-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2099 | [找到和最大的长度为 K 的子序列](../../problems/find-subsequence-of-length-k-with-the-largest-sum) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 2098 | [Subsequence of Size K With the Largest Even Sum](../../problems/subsequence-of-size-k-with-the-largest-even-sum) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2094 | [找出 3 位偶数](../../problems/finding-3-digit-even-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2092 | [找出知晓秘密的所有专家](../../problems/find-all-people-with-secret) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2089 | [找出数组排序后的目标下标](../../problems/find-target-indices-after-sorting-array) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2071 | [你可以安排的最多任务数目](../../problems/maximum-number-of-tasks-you-can-assign) | [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[单调队列](../monotonic-queue/README.md)]  | Hard |
-| 2070 | [每一个查询的最大美丽值](../../problems/most-beautiful-item-for-each-query) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2054 | [两个最好的不重叠活动](../../problems/two-best-non-overlapping-events) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2046 | [给按照绝对值排序的链表排序](../../problems/sort-linked-list-already-sorted-using-absolute-values) 🔒 | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2037 | [使每位学生都有座位的最少移动次数](../../problems/minimum-number-of-moves-to-seat-everyone) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 2033 | [获取单值网格的最小操作数](../../problems/minimum-operations-to-make-a-uni-value-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2015 | [Average Height of Buildings in Each Segment](../../problems/average-height-of-buildings-in-each-segment) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 2008 | [出租车的最大盈利](../../problems/maximum-earnings-from-taxi) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2007 | [从双倍数组中还原原数组](../../problems/find-original-array-from-doubled-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1998 | [数组的最大公因数排序](../../problems/gcd-sort-of-an-array) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1996 | [游戏中弱角色的数量](../../problems/the-number-of-weak-characters-in-the-game) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1985 | [找出数组中的第 K 大整数](../../problems/find-the-kth-largest-integer-in-the-array) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1984 | [学生分数的最小差值](../../problems/minimum-difference-between-highest-and-lowest-of-k-scores) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1968 | [构造元素不等于两相邻元素平均值的数组](../../problems/array-with-elements-not-equal-to-average-of-neighbors) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1921 | [消灭怪物的最大数量](../../problems/eliminate-maximum-number-of-monsters) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1913 | [两个数对之间的最大乘积差](../../problems/maximum-product-difference-between-two-pairs) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1889 | [装包裹的最小浪费空间](../../problems/minimum-space-wasted-from-packaging) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1887 | [使数组元素相等的减少操作次数](../../problems/reduction-operations-to-make-the-array-elements-equal) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1885 | [统计数对](../../problems/count-pairs-in-two-arrays) 🔒 | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1878 | [矩阵中最大的三个菱形和](../../problems/get-biggest-three-rhombus-sums-in-a-grid) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1877 | [数组中最大数对和的最小值](../../problems/minimize-maximum-pair-sum-in-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1874 | [两个数组的最小乘积和](../../problems/minimize-product-sum-of-two-arrays) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1859 | [将句子排序](../../problems/sorting-the-sentence) | [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1851 | [包含每个查询的最小区间](../../problems/minimum-interval-to-include-each-query) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[扫描线](../line-sweep/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1847 | [最近的房间](../../problems/closest-room) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1846 | [减小和重新排列数组后的最大元素](../../problems/maximum-element-after-decreasing-and-rearranging) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1834 | [单线程 CPU](../../problems/single-threaded-cpu) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1833 | [雪糕的最大数量](../../problems/maximum-ice-cream-bars) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1818 | [绝对差值和](../../problems/minimum-absolute-sum-difference) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1772 | [按受欢迎程度排列功能](../../problems/sort-features-by-popularity) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1727 | [重新排列后的最大子矩阵](../../problems/largest-submatrix-with-rearrangements) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1710 | [卡车上的最大单元数](../../problems/maximum-units-on-a-truck) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1697 | [检查边长度限制的路径是否存在](../../problems/checking-existence-of-edge-length-limited-paths) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1691 | [堆叠长方体的最大高度](../../problems/maximum-height-by-stacking-cuboids) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1686 | [石子游戏 VI](../../problems/stone-game-vi) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1679 | [K 和数对的最大数目](../../problems/max-number-of-k-sum-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1665 | [完成所有任务的最少初始能量](../../problems/minimum-initial-energy-to-finish-tasks) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1657 | [确定两个字符串是否接近](../../problems/determine-if-two-strings-are-close) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1648 | [销售价值减少的颜色球](../../problems/sell-diminishing-valued-colored-balls) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1647 | [字符频次唯一的最小删除次数](../../problems/minimum-deletions-to-make-character-frequencies-unique) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1637 | [两点之间不包含任何点的最宽垂直面积](../../problems/widest-vertical-area-between-two-points-containing-no-points) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1636 | [按照频率将数组升序排序](../../problems/sort-array-by-increasing-frequency) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1630 | [等差子数组](../../problems/arithmetic-subarrays) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1626 | [无矛盾的最佳球队](../../problems/best-team-with-no-conflicts) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1619 | [删除某些元素后的数组均值](../../problems/mean-of-array-after-removing-some-elements) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1610 | [可见点的最大数目](../../problems/maximum-number-of-visible-points) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 1608 | [特殊数组的特征值](../../problems/special-array-with-x-elements-greater-than-or-equal-x) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1604 | [警告一小时内使用相同员工卡大于等于三次的人](../../problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1589 | [所有排列中的最大和](../../problems/maximum-sum-obtained-of-any-permutation) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1585 | [检查字符串是否可以通过排序子字符串得到另一个字符串](../../problems/check-if-string-is-transformable-with-substring-sort-operations) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1580 | [把箱子放进仓库里 II](../../problems/put-boxes-into-the-warehouse-ii) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1564 | [把箱子放进仓库里 I](../../problems/put-boxes-into-the-warehouse-i) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1561 | [你可以获得的最大硬币数目](../../problems/maximum-number-of-coins-you-can-get) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[博弈](../game-theory/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1552 | [两球之间的磁力](../../problems/magnetic-force-between-two-balls) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1509 | [三次操作后最大值与最小值的最小差](../../problems/minimum-difference-between-largest-and-smallest-value-in-three-moves) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1508 | [子数组和排序后的区间和](../../problems/range-sum-of-sorted-subarray-sums) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1502 | [判断能否形成等差数列](../../problems/can-make-arithmetic-progression-from-sequence) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1498 | [满足条件的子序列数目](../../problems/number-of-subsequences-that-satisfy-the-given-sum-condition) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1491 | [去掉最低工资和最高工资后的工资平均值](../../problems/average-salary-excluding-the-minimum-and-maximum-salary) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1489 | [找到最小生成树里的关键边和伪关键边](../../problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)] [[排序](../sorting/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
-| 1481 | [不同整数的最少数目](../../problems/least-number-of-unique-integers-after-k-removals) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1478 | [安排邮筒](../../problems/allocate-mailboxes) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1471 | [数组中的 k 个最强值](../../problems/the-k-strongest-values-in-an-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1465 | [切割后面积最大的蛋糕](../../problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1464 | [数组中两元素的最大乘积](../../problems/maximum-product-of-two-elements-in-an-array) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 1460 | [通过翻转子数组使两个数组相等](../../problems/make-two-arrays-equal-by-reversing-sub-arrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1451 | [重新排列句子中的单词](../../problems/rearrange-words-in-a-sentence) | [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1433 | [检查一个字符串是否可以打破另一个字符串](../../problems/check-if-a-string-can-break-another-string) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1424 | [对角线遍历 II](../../problems/diagonal-traverse-ii) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1418 | [点菜展示表](../../problems/display-table-of-food-orders-in-a-restaurant) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1403 | [非递增顺序的最小子序列](../../problems/minimum-subsequence-in-non-increasing-order) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1402 | [做菜顺序](../../problems/reducing-dishes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1387 | [将整数按权重排序](../../problems/sort-integers-by-the-power-value) | [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1385 | [两个数组间的距离值](../../problems/find-the-distance-value-between-two-arrays) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1383 | [最大的团队表现值](../../problems/maximum-performance-of-a-team) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1366 | [通过投票对团队排名](../../problems/rank-teams-by-votes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1365 | [有多少小于当前数字的数字](../../problems/how-many-numbers-are-smaller-than-the-current-number) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1356 | [根据数字二进制下 1 的数目排序](../../problems/sort-integers-by-the-number-of-1-bits) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1348 | [推文计数](../../problems/tweet-counts-per-frequency) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1346 | [检查整数及其两倍数是否存在](../../problems/check-if-n-and-its-double-exist) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1340 | [跳跃游戏 V](../../problems/jump-game-v) | [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1338 | [数组大小减半](../../problems/reduce-array-size-to-the-half) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1337 | [矩阵中战斗力最弱的 K 行](../../problems/the-k-weakest-rows-in-a-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 1333 | [餐厅过滤器](../../problems/filter-restaurants-by-vegan-friendly-price-and-distance) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1331 | [数组序号转换](../../problems/rank-transform-of-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1329 | [将矩阵按对角线排序](../../problems/sort-the-matrix-diagonally) | [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1311 | [获取你好友已观看的视频](../../problems/get-watched-videos-by-your-friends) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1305 | [两棵二叉搜索树中的所有元素](../../problems/all-elements-in-two-binary-search-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1300 | [转变数组后最接近目标值的数组和](../../problems/sum-of-mutated-array-closest-to-target) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1296 | [划分数组为连续数字的集合](../../problems/divide-array-in-sets-of-k-consecutive-numbers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1288 | [删除被覆盖区间](../../problems/remove-covered-intervals) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1244 | [力扣排行榜](../../problems/design-a-leaderboard) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1235 | [规划兼职工作](../../problems/maximum-profit-in-job-scheduling) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1229 | [安排会议日程](../../problems/meeting-scheduler) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1200 | [最小绝对差](../../problems/minimum-absolute-difference) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1196 | [最多可以买到的苹果数量](../../problems/how-many-apples-can-you-put-into-the-basket) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1181 | [前后拼接](../../problems/before-and-after-puzzle) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1170 | [比较字符串最小字母出现频次](../../problems/compare-strings-by-frequency-of-the-smallest-character) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1169 | [查询无效交易](../../problems/invalid-transactions) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1152 | [用户网站访问行为分析](../../problems/analyze-user-website-visit-pattern) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1133 | [最大唯一数](../../problems/largest-unique-number) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1122 | [数组的相对排序](../../problems/relative-sort-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1099 | [小于 K 的两数之和](../../problems/two-sum-less-than-k) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1094 | [拼车](../../problems/car-pooling) | [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1090 | [受标签影响的最大值](../../problems/largest-values-from-labels) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1086 | [前五科的均分](../../problems/high-five) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1065 | [字符串的索引对](../../problems/index-pairs-of-a-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1057 | [校园自行车分配](../../problems/campus-bikes) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1054 | [距离相等的条形码](../../problems/distant-barcodes) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1051 | [高度检查器](../../problems/height-checker) | [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1040 | [移动石子直到连续 II](../../problems/moving-stones-until-consecutive-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1030 | [距离顺序排列矩阵单元格](../../problems/matrix-cells-in-distance-order) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1029 | [两地调度](../../problems/two-city-scheduling) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1005 | [K 次取反后最大化的数组和](../../problems/maximize-sum-of-array-after-k-negations) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 977 | [有序数组的平方](../../problems/squares-of-a-sorted-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 976 | [三角形的最大周长](../../problems/largest-perimeter-triangle) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 973 | [最接近原点的 K 个点](../../problems/k-closest-points-to-origin) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 969 | [煎饼排序](../../problems/pancake-sorting) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 954 | [二倍数对数组](../../problems/array-of-doubled-pairs) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 950 | [按递增顺序显示卡牌](../../problems/reveal-cards-in-increasing-order) | [[队列](../queue/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 948 | [令牌放置](../../problems/bag-of-tokens) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 945 | [使数组唯一的最小增量](../../problems/minimum-increment-to-make-array-unique) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 939 | [最小面积矩形](../../problems/minimum-area-rectangle) | [[几何](../geometry/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 937 | [重新排列日志文件](../../problems/reorder-data-in-log-files) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 923 | [三数之和的多种可能](../../problems/3sum-with-multiplicity) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 922 | [按奇偶排序数组 II](../../problems/sort-array-by-parity-ii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 912 | [排序数组](../../problems/sort-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数排序](../counting-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 910 | [最小差值 II](../../problems/smallest-range-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 905 | [按奇偶排序数组](../../problems/sort-array-by-parity) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 899 | [有序队列](../../problems/orderly-queue) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 891 | [子序列宽度之和](../../problems/sum-of-subsequence-widths) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 888 | [公平的糖果交换](../../problems/fair-candy-swap) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 881 | [救生艇](../../problems/boats-to-save-people) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 870 | [优势洗牌](../../problems/advantage-shuffle) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 869 | [重新排序得到 2 的幂](../../problems/reordered-power-of-2) | [[数学](../math/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 857 | [雇佣 K 名工人的最低成本](../../problems/minimum-cost-to-hire-k-workers) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 853 | [车队](../../problems/car-fleet) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 846 | [一手顺子](../../problems/hand-of-straights) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 833 | [字符串中的查找与替换](../../problems/find-and-replace-in-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 826 | [安排工作以达到最大收益](../../problems/most-profit-assigning-work) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 825 | [适龄的朋友](../../problems/friends-of-appropriate-ages) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 792 | [匹配子序列的单词数](../../problems/number-of-matching-subsequences) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 791 | [自定义字符串排序](../../problems/custom-sort-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 769 | [最多能完成排序的块](../../problems/max-chunks-to-make-sorted) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 768 | [最多能完成排序的块 II](../../problems/max-chunks-to-make-sorted-ii) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 767 | [重构字符串](../../problems/reorganize-string) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 759 | [员工空闲时间](../../problems/employee-free-time) 🔒 | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 757 | [设置交集大小至少为2](../../problems/set-intersection-size-at-least-two) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 747 | [至少是其他数字两倍的最大数](../../problems/largest-number-at-least-twice-of-others) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 726 | [原子的数量](../../problems/number-of-atoms) | [[栈](../stack/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 720 | [词典中最长的单词](../../problems/longest-word-in-dictionary) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 719 | [找出第 k 小的距离对](../../problems/find-k-th-smallest-pair-distance) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 710 | [黑名单中的随机数](../../problems/random-pick-with-blacklist) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[随机化](../randomized/README.md)]  | Hard |
-| 692 | [前K个高频单词](../../problems/top-k-frequent-words) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 658 | [找到 K 个最接近的元素](../../problems/find-k-closest-elements) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 646 | [最长数对链](../../problems/maximum-length-of-pair-chain) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 645 | [错误的集合](../../problems/set-mismatch) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 632 | [最小区间](../../problems/smallest-range-covering-elements-from-k-lists) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 628 | [三个数的最大乘积](../../problems/maximum-product-of-three-numbers) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 621 | [任务调度器](../../problems/task-scheduler) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 611 | [有效三角形的个数](../../problems/valid-triangle-number) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 594 | [最长和谐子序列](../../problems/longest-harmonious-subsequence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 581 | [最短无序连续子数组](../../problems/shortest-unsorted-continuous-subarray) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 561 | [数组拆分 I](../../problems/array-partition-i) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 539 | [最小时间差](../../problems/minimum-time-difference) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 532 | [数组中的 k-diff 数对](../../problems/k-diff-pairs-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 527 | [单词缩写](../../problems/word-abbreviation) 🔒 | [[贪心](../greedy/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 524 | [通过删除字母匹配到字典里最长单词](../../problems/longest-word-in-dictionary-through-deleting) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 522 | [最长特殊序列 II](../../problems/longest-uncommon-subsequence-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 506 | [相对名次](../../problems/relative-ranks) | [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 502 | [IPO](../../problems/ipo) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 475 | [供暖器](../../problems/heaters) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 462 | [最少移动次数使数组元素相等 II](../../problems/minimum-moves-to-equal-array-elements-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 455 | [分发饼干](../../problems/assign-cookies) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 452 | [用最少数量的箭引爆气球](../../problems/minimum-number-of-arrows-to-burst-balloons) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 451 | [根据字符出现频率排序](../../problems/sort-characters-by-frequency) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 436 | [寻找右区间](../../problems/find-right-interval) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 435 | [无重叠区间](../../problems/non-overlapping-intervals) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 414 | [第三大的数](../../problems/third-maximum-number) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 406 | [根据身高重建队列](../../problems/queue-reconstruction-by-height) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 389 | [找不同](../../problems/find-the-difference) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 378 | [有序矩阵中第 K 小的元素](../../problems/kth-smallest-element-in-a-sorted-matrix) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 368 | [最大整除子集](../../problems/largest-divisible-subset) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 360 | [有序转化数组](../../problems/sort-transformed-array) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 358 | [K 距离间隔重排字符串](../../problems/rearrange-string-k-distance-apart) 🔒 | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 354 | [俄罗斯套娃信封问题](../../problems/russian-doll-envelopes) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 350 | [两个数组的交集 II](../../problems/intersection-of-two-arrays-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 349 | [两个数组的交集](../../problems/intersection-of-two-arrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 347 | [前 K 个高频元素](../../problems/top-k-frequent-elements) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 324 | [摆动排序 II](../../problems/wiggle-sort-ii) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 296 | [最佳的碰头地点](../../problems/best-meeting-point) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[矩阵](../matrix/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 295 | [数据流的中位数](../../problems/find-median-from-data-stream) | [[设计](../design/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 280 | [摆动排序](../../problems/wiggle-sort) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 274 | [H 指数](../../problems/h-index) | [[数组](../array/README.md)] [[计数排序](../counting-sort/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 268 | [丢失的数字](../../problems/missing-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 259 | [较小的三数之和](../../problems/3sum-smaller) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 253 | [会议室 II](../../problems/meeting-rooms-ii) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 252 | [会议室](../../problems/meeting-rooms) 🔒 | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 242 | [有效的字母异位词](../../problems/valid-anagram) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 229 | [求众数 II](../../problems/majority-element-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 220 | [存在重复元素 III](../../problems/contains-duplicate-iii) | [[数组](../array/README.md)] [[桶排序](../bucket-sort/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 217 | [存在重复元素](../../problems/contains-duplicate) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 215 | [数组中的第K个最大元素](../../problems/kth-largest-element-in-an-array) | [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 179 | [最大数](../../problems/largest-number) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 169 | [多数元素](../../problems/majority-element) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 164 | [最大间距](../../problems/maximum-gap) | [[数组](../array/README.md)] [[桶排序](../bucket-sort/README.md)] [[基数排序](../radix-sort/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 148 | [排序链表](../../problems/sort-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)] [[分治](../divide-and-conquer/README.md)] [[排序](../sorting/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 147 | [对链表进行插入排序](../../problems/insertion-sort-list) | [[链表](../linked-list/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 88 | [合并两个有序数组](../../problems/merge-sorted-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 75 | [颜色分类](../../problems/sort-colors) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 56 | [合并区间](../../problems/merge-intervals) | [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 49 | [字母异位词分组](../../problems/group-anagrams) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 18 | [四数之和](../../problems/4sum) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 16 | [最接近的三数之和](../../problems/3sum-closest) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 15 | [三数之和](../../problems/3sum) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
diff --git a/tag/stack/README.md b/tag/stack/README.md
deleted file mode 100644
index fa5f7a7cd..000000000
--- a/tag/stack/README.md
+++ /dev/null
@@ -1,130 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 栈
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2130 | [链表最大孪生和](../../problems/maximum-twin-sum-of-a-linked-list) | [[栈](../stack/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 2116 | [判断一个括号字符串是否有效](../../problems/check-if-a-parentheses-string-can-be-valid) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2104 | [子数组范围和](../../problems/sum-of-subarray-ranges) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 2030 | [含特定字母的最小子序列](../../problems/smallest-k-length-subsequence-with-occurrences-of-a-letter) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 2019 | [解出数学表达式的学生分数](../../problems/the-score-of-students-solving-math-expression) | [[栈](../stack/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1996 | [游戏中弱角色的数量](../../problems/the-number-of-weak-characters-in-the-game) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1963 | [使字符串平衡的最小交换次数](../../problems/minimum-number-of-swaps-to-make-the-string-balanced) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1950 | [所有子数组最小值中的最大值](../../problems/maximum-of-minimum-values-in-all-subarrays) 🔒 | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1944 | [队列中可以看到的人数](../../problems/number-of-visible-people-in-a-queue) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1896 | [反转表达式值的最少操作次数](../../problems/minimum-cost-to-change-the-final-value-of-expression) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1856 | [子数组最小乘积的最大值](../../problems/maximum-subarray-min-product) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[前缀和](../prefix-sum/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1793 | [好子数组的最大分数](../../problems/maximum-score-of-a-good-subarray) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1776 | [车队 II](../../problems/car-fleet-ii) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[单调栈](../monotonic-stack/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1762 | [能看到海景的建筑物](../../problems/buildings-with-an-ocean-view) 🔒 | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1756 | [设计最近使用（MRU）队列](../../problems/design-most-recently-used-queue) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1717 | [删除子字符串的最大得分](../../problems/maximum-score-from-removing-substrings) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1700 | [无法吃午餐的学生数量](../../problems/number-of-students-unable-to-eat-lunch) | [[栈](../stack/README.md)] [[队列](../queue/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1673 | [找出最具竞争力的子序列](../../problems/find-the-most-competitive-subsequence) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1653 | [使字符串平衡的最少删除次数](../../problems/minimum-deletions-to-make-string-balanced) | [[栈](../stack/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1628 | [设计带解析函数的表达式树](../../problems/design-an-expression-tree-with-evaluate-function) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[数学](../math/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1614 | [括号的最大嵌套深度](../../problems/maximum-nesting-depth-of-the-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1598 | [文件夹操作日志搜集器](../../problems/crawler-log-folder) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1597 | [根据中缀表达式构造二叉表达式树](../../problems/build-binary-expression-tree-from-infix-expression) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1586 | [二叉搜索树迭代器 II](../../problems/binary-search-tree-iterator-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 1574 | [删除最短的子数组使剩余数组有序](../../problems/shortest-subarray-to-be-removed-to-make-array-sorted) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1544 | [整理字符串](../../problems/make-the-string-great) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1541 | [平衡括号字符串的最少插入次数](../../problems/minimum-insertions-to-balance-a-parentheses-string) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1526 | [形成目标数组的子数组最少增加次数](../../problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1504 | [统计全 1 子矩形](../../problems/count-submatrices-with-all-ones) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1475 | [商品折扣后的最终价格](../../problems/final-prices-with-a-special-discount-in-a-shop) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Easy |
-| 1472 | [设计浏览器历史记录](../../problems/design-browser-history) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[数据流](../data-stream/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 1441 | [用栈操作构建数组](../../problems/build-an-array-with-stack-operations) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1381 | [设计一个支持增量操作的栈](../../problems/design-a-stack-with-increment-operation) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1265 | [逆序打印不可变链表](../../problems/print-immutable-linked-list-in-reverse) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1249 | [移除无效的括号](../../problems/minimum-remove-to-make-valid-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1214 | [查找两棵二叉搜索树之和](../../problems/two-sum-bsts) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1209 | [删除字符串中的所有相邻重复项 II](../../problems/remove-all-adjacent-duplicates-in-string-ii) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1190 | [反转每对括号间的子串](../../problems/reverse-substrings-between-each-pair-of-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1172 | [餐盘栈](../../problems/dinner-plate-stacks) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 1130 | [叶值的最小代价生成树](../../problems/minimum-cost-tree-from-leaf-values) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1124 | [表现良好的最长时间段](../../problems/longest-well-performing-interval) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[前缀和](../prefix-sum/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1111 | [有效括号的嵌套深度](../../problems/maximum-nesting-depth-of-two-valid-parentheses-strings) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1106 | [解析布尔表达式](../../problems/parsing-a-boolean-expression) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1096 | [花括号展开 II](../../problems/brace-expansion-ii) | [[栈](../stack/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1081 | [不同字符的最小子序列](../../problems/smallest-subsequence-of-distinct-characters) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1063 | [有效子数组的数目](../../problems/number-of-valid-subarrays) 🔒 | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1047 | [删除字符串中的所有相邻重复项](../../problems/remove-all-adjacent-duplicates-in-string) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1021 | [删除最外层的括号](../../problems/remove-outermost-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1019 | [链表中的下一个更大节点](../../problems/next-greater-node-in-linked-list) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[链表](../linked-list/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1008 | [前序遍历构造二叉搜索树](../../problems/construct-binary-search-tree-from-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1006 | [笨阶乘](../../problems/clumsy-factorial) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1003 | [检查替换后的词是否有效](../../problems/check-if-word-is-valid-after-substitutions) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 975 | [奇偶跳](../../problems/odd-even-jump) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 962 | [最大宽度坡](../../problems/maximum-width-ramp) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 946 | [验证栈序列](../../problems/validate-stack-sequences) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 936 | [戳印序列](../../problems/stamping-the-sequence) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 921 | [使括号有效的最少添加](../../problems/minimum-add-to-make-parentheses-valid) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 907 | [子数组的最小值之和](../../problems/sum-of-subarray-minimums) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 901 | [股票价格跨度](../../problems/online-stock-span) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[数据流](../data-stream/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 897 | [递增顺序搜索树](../../problems/increasing-order-search-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 895 | [最大频率栈](../../problems/maximum-frequency-stack) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 880 | [索引处的解码字符串](../../problems/decoded-string-at-index) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 856 | [括号的分数](../../problems/score-of-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 853 | [车队](../../problems/car-fleet) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 844 | [比较含退格的字符串](../../problems/backspace-string-compare) | [[栈](../stack/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 772 | [基本计算器 III](../../problems/basic-calculator-iii) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 770 | [基本计算器 IV](../../problems/basic-calculator-iv) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 769 | [最多能完成排序的块](../../problems/max-chunks-to-make-sorted) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 768 | [最多能完成排序的块 II](../../problems/max-chunks-to-make-sorted-ii) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 739 | [每日温度](../../problems/daily-temperatures) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 736 | [Lisp 语法解析](../../problems/parse-lisp-expression) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 735 | [行星碰撞](../../problems/asteroid-collision) | [[栈](../stack/README.md)] [[数组](../array/README.md)]  | Medium |
-| 726 | [原子的数量](../../problems/number-of-atoms) | [[栈](../stack/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 716 | [最大栈](../../problems/max-stack) 🔒 | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[链表](../linked-list/README.md)] [[双向链表](../doubly-linked-list/README.md)] [[有序集合](../ordered-set/README.md)]  | Easy |
-| 682 | [棒球比赛](../../problems/baseball-game) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 678 | [有效的括号字符串](../../problems/valid-parenthesis-string) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 654 | [最大二叉树](../../problems/maximum-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 636 | [函数的独占时间](../../problems/exclusive-time-of-functions) | [[栈](../stack/README.md)] [[数组](../array/README.md)]  | Medium |
-| 591 | [标签验证器](../../problems/tag-validator) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 590 | [N 叉树的后序遍历](../../problems/n-ary-tree-postorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Easy |
-| 589 | [N 叉树的前序遍历](../../problems/n-ary-tree-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Easy |
-| 581 | [最短无序连续子数组](../../problems/shortest-unsorted-continuous-subarray) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 503 | [下一个更大元素 II](../../problems/next-greater-element-ii) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 496 | [下一个更大元素 I](../../problems/next-greater-element-i) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Easy |
-| 484 | [寻找排列](../../problems/find-permutation) 🔒 | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)]  | Medium |
-| 456 | [132 模式](../../problems/132-pattern) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[有序集合](../ordered-set/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 445 | [两数相加 II](../../problems/add-two-numbers-ii) | [[栈](../stack/README.md)] [[链表](../linked-list/README.md)] [[数学](../math/README.md)]  | Medium |
-| 439 | [三元表达式解析器](../../problems/ternary-expression-parser) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 426 | [将二叉搜索树转化为排序的双向链表](../../problems/convert-binary-search-tree-to-sorted-doubly-linked-list) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 402 | [移掉 K 位数字](../../problems/remove-k-digits) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 394 | [字符串解码](../../problems/decode-string) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 388 | [文件的最长绝对路径](../../problems/longest-absolute-file-path) | [[栈](../stack/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 385 | [迷你语法分析器](../../problems/mini-parser) | [[栈](../stack/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 364 | [加权嵌套序列和 II](../../problems/nested-list-weight-sum-ii) 🔒 | [[栈](../stack/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 341 | [扁平化嵌套列表迭代器](../../problems/flatten-nested-list-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 331 | [验证二叉树的前序序列化](../../problems/verify-preorder-serialization-of-a-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 321 | [拼接最大数](../../problems/create-maximum-number) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 316 | [去除重复字母](../../problems/remove-duplicate-letters) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 272 | [最接近的二叉搜索树值 II](../../problems/closest-binary-search-tree-value-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 255 | [验证前序遍历序列二叉搜索树](../../problems/verify-preorder-sequence-in-binary-search-tree) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 234 | [回文链表](../../problems/palindrome-linked-list) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 232 | [用栈实现队列](../../problems/implement-queue-using-stacks) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)]  | Easy |
-| 227 | [基本计算器 II](../../problems/basic-calculator-ii) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 225 | [用队列实现栈](../../problems/implement-stack-using-queues) | [[栈](../stack/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)]  | Easy |
-| 224 | [基本计算器](../../problems/basic-calculator) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 173 | [二叉搜索树迭代器](../../problems/binary-search-tree-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 155 | [最小栈](../../problems/min-stack) | [[栈](../stack/README.md)] [[设计](../design/README.md)]  | Easy |
-| 150 | [逆波兰表达式求值](../../problems/evaluate-reverse-polish-notation) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Medium |
-| 145 | [二叉树的后序遍历](../../problems/binary-tree-postorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 144 | [二叉树的前序遍历](../../problems/binary-tree-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 143 | [重排链表](../../problems/reorder-list) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 114 | [二叉树展开为链表](../../problems/flatten-binary-tree-to-linked-list) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 94 | [二叉树的中序遍历](../../problems/binary-tree-inorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 85 | [最大矩形](../../problems/maximal-rectangle) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[动态规划](../dynamic-programming/README.md)] [[矩阵](../matrix/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 84 | [柱状图中最大的矩形](../../problems/largest-rectangle-in-histogram) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 71 | [简化路径](../../problems/simplify-path) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 42 | [接雨水](../../problems/trapping-rain-water) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 32 | [最长有效括号](../../problems/longest-valid-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 20 | [有效的括号](../../problems/valid-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
diff --git a/tag/string-matching/README.md b/tag/string-matching/README.md
deleted file mode 100644
index 304b8dd22..000000000
--- a/tag/string-matching/README.md
+++ /dev/null
@@ -1,26 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 字符串匹配
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1764 | [通过连接另一个数组的子数组得到一个数组](../../problems/form-array-by-concatenating-subarrays-of-another-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 1668 | [最大重复子字符串](../../problems/maximum-repeating-substring) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 1455 | [检查单词是否为句中其他单词的前缀](../../problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 1408 | [数组中的字符串匹配](../../problems/string-matching-in-an-array) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 1397 | [找到所有好字符串](../../problems/find-all-good-strings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[字符串匹配](../string-matching/README.md)]  | Hard |
-| 1392 | [最长快乐前缀](../../problems/longest-happy-prefix) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1023 | [驼峰式匹配](../../problems/camelcase-matching) | [[字典树](../trie/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 796 | [旋转字符串](../../problems/rotate-string) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 758 | [字符串中的加粗单词](../../problems/bold-words-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 686 | [重复叠加字符串匹配](../../problems/repeated-string-match) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 616 | [给字符串添加加粗标签](../../problems/add-bold-tag-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 572 | [另一棵树的子树](../../problems/subtree-of-another-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 459 | [重复的子字符串](../../problems/repeated-substring-pattern) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 214 | [最短回文串](../../problems/shortest-palindrome) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 28 | [实现 strStr()](../../problems/implement-strstr) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
diff --git a/tag/string/README.md b/tag/string/README.md
deleted file mode 100644
index 0a015eeb0..000000000
--- a/tag/string/README.md
+++ /dev/null
@@ -1,521 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 字符串
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2168 | [Unique Substrings With Equal Digit Frequency](../../problems/unique-substrings-with-equal-digit-frequency) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 2167 | [移除所有载有违禁货物车厢所需的最少时间](../../problems/minimum-time-to-remove-all-cars-containing-illegal-goods) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2157 | [字符串分组](../../problems/groups-of-strings) | [[位运算](../bit-manipulation/README.md)] [[并查集](../union-find/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 2156 | [查找给定哈希值的子串](../../problems/find-substring-with-given-hash-value) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 2147 | [分隔长廊的方案数](../../problems/number-of-ways-to-divide-a-long-corridor) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2138 | [将字符串拆分为若干长度为 k 的组](../../problems/divide-a-string-into-groups-of-size-k) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2135 | [统计追加字母可以获得的单词数](../../problems/count-words-obtained-after-adding-a-letter) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2131 | [连接两字母单词得到的最长回文串](../../problems/longest-palindrome-by-concatenating-two-letter-words) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 2129 | [将标题首字母大写](../../problems/capitalize-the-title) | [[字符串](../string/README.md)]  | Easy |
-| 2125 | [银行中的激光束数量](../../problems/number-of-laser-beams-in-a-bank) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 2124 | [检查是否所有 A 都在 B 之前](../../problems/check-if-all-as-appears-before-all-bs) | [[字符串](../string/README.md)]  | Easy |
-| 2120 | [执行所有后缀指令](../../problems/execution-of-all-suffix-instructions-staying-in-a-grid) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2116 | [判断一个括号字符串是否有效](../../problems/check-if-a-parentheses-string-can-be-valid) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2115 | [从给定原材料中找到所有可以做出的菜](../../problems/find-all-possible-recipes-from-given-supplies) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2114 | [句子中的最多单词数](../../problems/maximum-number-of-words-found-in-sentences) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2109 | [向字符串添加空格](../../problems/adding-spaces-to-a-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2108 | [找出数组中的第一个回文字符串](../../problems/find-first-palindromic-string-in-the-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2103 | [环和杆](../../problems/rings-and-rods) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2096 | [从二叉树一个节点到另一个节点每一步的方向](../../problems/step-by-step-directions-from-a-binary-tree-node-to-another) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 2086 | [从房屋收集雨水需要的最少水桶数](../../problems/minimum-number-of-buckets-required-to-collect-rainwater-from-houses) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 2085 | [统计出现过一次的公共字符串](../../problems/count-common-words-with-one-occurrence) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2083 | [求以相同字母开头和结尾的子串总数](../../problems/substrings-that-begin-and-end-with-the-same-letter) 🔒 | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2075 | [解码斜向换位密码](../../problems/decode-the-slanted-ciphertext) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2068 | [检查两个字符串是否几乎相等](../../problems/check-whether-two-strings-are-almost-equivalent) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2067 | [Number of Equal Count Substrings](../../problems/number-of-equal-count-substrings) 🔒 | [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2063 | [所有子字符串中的元音](../../problems/vowels-of-all-substrings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Medium |
-| 2062 | [统计字符串中的元音子字符串](../../problems/count-vowel-substrings-of-a-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2060 | [同源字符串检测](../../problems/check-if-an-original-string-exists-given-two-encoded-strings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2056 | [棋盘上有效移动组合的数目](../../problems/number-of-valid-move-combinations-on-chessboard) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 2055 | [蜡烛之间的盘子](../../problems/plates-between-candles) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 2053 | [数组中第 K 个独一无二的字符串](../../problems/kth-distinct-string-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 2047 | [句子中的有效单词数](../../problems/number-of-valid-words-in-a-sentence) | [[字符串](../string/README.md)]  | Easy |
-| 2042 | [检查句子中的数字是否递增](../../problems/check-if-numbers-are-ascending-in-a-sentence) | [[字符串](../string/README.md)]  | Easy |
-| 2038 | [如果相邻两个颜色均相同则删除当前颜色](../../problems/remove-colored-pieces-if-both-neighbors-are-the-same-color) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[博弈](../game-theory/README.md)]  | Medium |
-| 2030 | [含特定字母的最小子序列](../../problems/smallest-k-length-subsequence-with-occurrences-of-a-letter) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 2027 | [转换字符串的最少操作次数](../../problems/minimum-moves-to-convert-string) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2024 | [考试的最大困扰度](../../problems/maximize-the-confusion-of-an-exam) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 2023 | [连接后等于目标字符串的字符串对](../../problems/number-of-pairs-of-strings-with-concatenation-equal-to-target) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2019 | [解出数学表达式的学生分数](../../problems/the-score-of-students-solving-math-expression) | [[栈](../stack/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 2014 | [重复 K 次的最长子序列](../../problems/longest-subsequence-repeated-k-times) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[计数](../counting/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 2011 | [执行操作后的变量值](../../problems/final-value-of-variable-after-performing-operations) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 2002 | [两个回文子序列长度的最大乘积](../../problems/maximum-product-of-the-length-of-two-palindromic-subsequences) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Medium |
-| 2000 | [反转单词前缀](../../problems/reverse-prefix-of-word) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1987 | [不同的好子序列数目](../../problems/number-of-unique-good-subsequences) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1985 | [找出数组中的第 K 大整数](../../problems/find-the-kth-largest-integer-in-the-array) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[快速选择](../quickselect/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1980 | [找出不同的二进制字符串](../../problems/find-unique-binary-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1977 | [划分数字的方案数](../../problems/number-of-ways-to-separate-numbers) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[后缀数组](../suffix-array/README.md)]  | Hard |
-| 1974 | [使用特殊打字机键入单词的最少时间](../../problems/minimum-time-to-type-word-using-special-typewriter) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1967 | [作为子字符串出现在单词中的字符串数目](../../problems/number-of-strings-that-appear-as-substrings-in-word) | [[字符串](../string/README.md)]  | Easy |
-| 1963 | [使字符串平衡的最小交换次数](../../problems/minimum-number-of-swaps-to-make-the-string-balanced) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1961 | [检查字符串是否为数组前缀](../../problems/check-if-string-is-a-prefix-of-array) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1960 | [两个回文子字符串长度的最大乘积](../../problems/maximum-product-of-the-length-of-two-palindromic-substrings) | [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1957 | [删除字符使字符串变好](../../problems/delete-characters-to-make-fancy-string) | [[字符串](../string/README.md)]  | Easy |
-| 1948 | [删除系统中的重复文件夹](../../problems/delete-duplicate-folders-in-system) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 1946 | [子字符串突变后可能得到的最大整数](../../problems/largest-number-after-mutating-substring) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1945 | [字符串转化后的各位数字之和](../../problems/sum-of-digits-of-string-after-convert) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 1941 | [检查是否所有字符出现次数相同](../../problems/check-if-all-characters-have-equal-number-of-occurrences) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1935 | [可以输入的最大单词数](../../problems/maximum-number-of-words-you-can-type) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1933 | [判断字符串是否可分解为值均等的子串](../../problems/check-if-string-is-decomposable-into-value-equal-substrings) 🔒 | [[字符串](../string/README.md)]  | Easy |
-| 1930 | [长度为 3 的不同回文子序列](../../problems/unique-length-3-palindromic-subsequences) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1915 | [最美子字符串的数目](../../problems/number-of-wonderful-substrings) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1910 | [删除一个字符串中所有出现的给定子字符串](../../problems/remove-all-occurrences-of-a-substring) | [[字符串](../string/README.md)]  | Medium |
-| 1904 | [你完成的完整对局数](../../problems/the-number-of-full-rounds-you-have-played) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1903 | [字符串中的最大奇数](../../problems/largest-odd-number-in-string) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1898 | [可移除字符的最大数目](../../problems/maximum-number-of-removable-characters) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1897 | [重新分配字符使所有字符串都相等](../../problems/redistribute-characters-to-make-all-strings-equal) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1896 | [反转表达式值的最少操作次数](../../problems/minimum-cost-to-change-the-final-value-of-expression) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1888 | [使二进制字符串字符交替的最少反转次数](../../problems/minimum-number-of-flips-to-make-the-binary-string-alternating) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1881 | [插入后的最大值](../../problems/maximum-value-after-insertion) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1880 | [检查某单词是否等于两单词之和](../../problems/check-if-word-equals-summation-of-two-words) | [[字符串](../string/README.md)]  | Easy |
-| 1876 | [长度为三且各字符不同的子字符串](../../problems/substrings-of-size-three-with-distinct-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1871 | [跳跃游戏 VII](../../problems/jump-game-vii) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1869 | [哪种连续子字符串更长](../../problems/longer-contiguous-segments-of-ones-than-zeros) | [[字符串](../string/README.md)]  | Easy |
-| 1864 | [构成交替字符串需要的最小交换次数](../../problems/minimum-number-of-swaps-to-make-the-binary-string-alternating) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1859 | [将句子排序](../../problems/sorting-the-sentence) | [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1850 | [邻位交换的最小次数](../../problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1849 | [将字符串拆分为递减的连续值](../../problems/splitting-a-string-into-descending-consecutive-values) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1844 | [将所有数字用字符替换](../../problems/replace-all-digits-with-characters) | [[字符串](../string/README.md)]  | Easy |
-| 1842 | [下个由相同数字构成的回文串](../../problems/next-palindrome-using-same-digits) 🔒 | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1839 | [所有元音按顺序排布的最长子字符串](../../problems/longest-substring-of-all-vowels-in-order) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1832 | [判断句子是否为全字母句](../../problems/check-if-the-sentence-is-pangram) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1830 | [使字符串有序的最少操作次数](../../problems/minimum-number-of-operations-to-make-string-sorted) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1816 | [截断句子](../../problems/truncate-sentence) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1813 | [句子相似性 III](../../problems/sentence-similarity-iii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1812 | [判断国际象棋棋盘中一个格子的颜色](../../problems/determine-color-of-a-chessboard-square) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1807 | [替换字符串中的括号内容](../../problems/evaluate-the-bracket-pairs-of-a-string) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1805 | [字符串中不同整数的数目](../../problems/number-of-different-integers-in-a-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1804 | [实现 Trie （前缀树） II](../../problems/implement-trie-ii-prefix-tree) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1796 | [字符串中第二大的数字](../../problems/second-largest-digit-in-a-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1794 | [统计距离最小的子串对个数](../../problems/count-pairs-of-equal-substrings-with-minimum-difference) 🔒 | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1790 | [仅执行一次字符串交换能否使两个字符串相等](../../problems/check-if-one-string-swap-can-make-strings-equal) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1784 | [检查二进制字符串字段](../../problems/check-if-binary-string-has-at-most-one-segment-of-ones) | [[字符串](../string/README.md)]  | Easy |
-| 1781 | [所有子字符串美丽值之和](../../problems/sum-of-beauty-of-all-substrings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1773 | [统计匹配检索规则的物品数量](../../problems/count-items-matching-a-rule) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1772 | [按受欢迎程度排列功能](../../problems/sort-features-by-popularity) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1771 | [由子序列构造的最长回文串的长度](../../problems/maximize-palindrome-length-from-subsequences) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1769 | [移动所有球到每个盒子所需的最小操作数](../../problems/minimum-number-of-operations-to-move-all-balls-to-each-box) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1768 | [交替合并字符串](../../problems/merge-strings-alternately) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1763 | [最长的美好子字符串](../../problems/longest-nice-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Easy |
-| 1759 | [统计同构子字符串的数目](../../problems/count-number-of-homogenous-substrings) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1758 | [生成交替二进制字符串的最少操作数](../../problems/minimum-changes-to-make-alternating-binary-string) | [[字符串](../string/README.md)]  | Easy |
-| 1754 | [构造字典序最大的合并字符串](../../problems/largest-merge-of-two-strings) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1750 | [删除字符串两端相同字符后的最短长度](../../problems/minimum-length-of-string-after-deleting-similar-ends) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1745 | [回文串分割 IV](../../problems/palindrome-partitioning-iv) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1737 | [满足三条件之一需改变的最少字符数](../../problems/change-minimum-characters-to-satisfy-one-of-three-conditions) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1736 | [替换隐藏数字得到的最晚时间](../../problems/latest-time-by-replacing-hidden-digits) | [[字符串](../string/README.md)]  | Easy |
-| 1717 | [删除子字符串的最大得分](../../problems/maximum-score-from-removing-substrings) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1704 | [判断字符串的两半是否相似](../../problems/determine-if-string-halves-are-alike) | [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1702 | [修改后的最大二进制字符串](../../problems/maximum-binary-string-after-change) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1698 | [字符串的不同子字符串个数](../../problems/number-of-distinct-substrings-in-a-string) 🔒 | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1694 | [重新格式化电话号码](../../problems/reformat-phone-number) | [[字符串](../string/README.md)]  | Easy |
-| 1689 | [十-二进制数的最少数目](../../problems/partitioning-into-minimum-number-of-deci-binary-numbers) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1684 | [统计一致字符串的数目](../../problems/count-the-number-of-consistent-strings) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1682 | [最长回文子序列 II](../../problems/longest-palindromic-subsequence-ii) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1678 | [设计 Goal 解析器](../../problems/goal-parser-interpretation) | [[字符串](../string/README.md)]  | Easy |
-| 1668 | [最大重复子字符串](../../problems/maximum-repeating-substring) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 1663 | [具有给定数值的最小字符串](../../problems/smallest-string-with-a-given-numeric-value) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1662 | [检查两个字符串数组是否相等](../../problems/check-if-two-string-arrays-are-equivalent) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1657 | [确定两个字符串是否接近](../../problems/determine-if-two-strings-are-close) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1653 | [使字符串平衡的最少删除次数](../../problems/minimum-deletions-to-make-string-balanced) | [[栈](../stack/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1647 | [字符频次唯一的最小删除次数](../../problems/minimum-deletions-to-make-character-frequencies-unique) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1639 | [通过给定词典构造目标字符串的方案数](../../problems/number-of-ways-to-form-a-target-string-given-a-dictionary) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1638 | [统计只差一个字符的子串数目](../../problems/count-substrings-that-differ-by-one-character) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1629 | [按键持续时间最长的键](../../problems/slowest-key) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1625 | [执行操作后字典序最小的字符串](../../problems/lexicographically-smallest-string-after-applying-operations) | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1624 | [两个相同字符之间的最长子字符串](../../problems/largest-substring-between-two-equal-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1618 | [找出适应屏幕的最大字号](../../problems/maximum-font-to-fit-a-sentence-in-a-screen) 🔒 | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1616 | [分割两个字符串得到回文串](../../problems/split-two-strings-to-make-palindrome) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1614 | [括号的最大嵌套深度](../../problems/maximum-nesting-depth-of-the-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1604 | [警告一小时内使用相同员工卡大于等于三次的人](../../problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1598 | [文件夹操作日志搜集器](../../problems/crawler-log-folder) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1597 | [根据中缀表达式构造二叉表达式树](../../problems/build-binary-expression-tree-from-infix-expression) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1593 | [拆分字符串使唯一子字符串的数目最大](../../problems/split-a-string-into-the-max-number-of-unique-substrings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1592 | [重新排列单词间的空格](../../problems/rearrange-spaces-between-words) | [[字符串](../string/README.md)]  | Easy |
-| 1585 | [检查字符串是否可以通过排序子字符串得到另一个字符串](../../problems/check-if-string-is-transformable-with-substring-sort-operations) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1578 | [使绳子变成彩色的最短时间](../../problems/minimum-time-to-make-rope-colorful) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1576 | [替换所有的问号](../../problems/replace-all-s-to-avoid-consecutive-repeating-characters) | [[字符串](../string/README.md)]  | Easy |
-| 1573 | [分割字符串的方案数](../../problems/number-of-ways-to-split-a-string) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1556 | [千位分隔数](../../problems/thousand-separator) | [[字符串](../string/README.md)]  | Easy |
-| 1554 | [只有一个不同字符的字符串](../../problems/strings-differ-by-one-character) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1545 | [找出第 N 个二进制字符串中的第 K 位](../../problems/find-kth-bit-in-nth-binary-string) | [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1544 | [整理字符串](../../problems/make-the-string-great) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1542 | [找出最长的超赞子字符串](../../problems/find-longest-awesome-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1541 | [平衡括号字符串的最少插入次数](../../problems/minimum-insertions-to-balance-a-parentheses-string) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1540 | [K 次操作转变字符串](../../problems/can-convert-string-in-k-moves) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1531 | [压缩字符串 II](../../problems/string-compression-ii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1529 | [最少的后缀翻转次数](../../problems/minimum-suffix-flips) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1528 | [重新排列字符串](../../problems/shuffle-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1525 | [字符串的好分割数目](../../problems/number-of-good-ways-to-split-a-string) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1520 | [最多的不重叠子字符串](../../problems/maximum-number-of-non-overlapping-substrings) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1513 | [仅含 1 的子串数](../../problems/number-of-substrings-with-only-1s) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1507 | [转变日期格式](../../problems/reformat-date) | [[字符串](../string/README.md)]  | Easy |
-| 1505 | [最多 K 次交换相邻数位后得到的最小整数](../../problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits) | [[贪心](../greedy/README.md)] [[树状数组](../binary-indexed-tree/README.md)] [[线段树](../segment-tree/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1496 | [判断路径是否相交](../../problems/path-crossing) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1487 | [保证文件名唯一](../../problems/making-file-names-unique) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1461 | [检查一个字符串是否包含所有长度为 K 的二进制子串](../../problems/check-if-a-string-contains-all-binary-codes-of-size-k) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1456 | [定长子串中元音的最大数目](../../problems/maximum-number-of-vowels-in-a-substring-of-given-length) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1455 | [检查单词是否为句中其他单词的前缀](../../problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 1452 | [收藏清单](../../problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1451 | [重新排列句子中的单词](../../problems/rearrange-words-in-a-sentence) | [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1447 | [最简分数](../../problems/simplified-fractions) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[数论](../number-theory/README.md)]  | Medium |
-| 1446 | [连续字符](../../problems/consecutive-characters) | [[字符串](../string/README.md)]  | Easy |
-| 1436 | [旅行终点站](../../problems/destination-city) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1433 | [检查一个字符串是否可以打破另一个字符串](../../problems/check-if-a-string-can-break-another-string) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1427 | [字符串的左右移](../../problems/perform-string-shifts) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1422 | [分割字符串的最大得分](../../problems/maximum-score-after-splitting-a-string) | [[字符串](../string/README.md)]  | Easy |
-| 1419 | [数青蛙](../../problems/minimum-number-of-frogs-croaking) | [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1418 | [点菜展示表](../../problems/display-table-of-food-orders-in-a-restaurant) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[有序集合](../ordered-set/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1417 | [重新格式化字符串](../../problems/reformat-the-string) | [[字符串](../string/README.md)]  | Easy |
-| 1416 | [恢复数组](../../problems/restore-the-array) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1415 | [长度为 n 的开心字符串中字典序第 k 小的字符串](../../problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1410 | [HTML 实体解析器](../../problems/html-entity-parser) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1408 | [数组中的字符串匹配](../../problems/string-matching-in-an-array) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 1405 | [最长快乐字符串](../../problems/longest-happy-string) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1404 | [将二进制表示减到 1 的步骤数](../../problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1400 | [构造 K 个回文字符串](../../problems/construct-k-palindrome-strings) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 1397 | [找到所有好字符串](../../problems/find-all-good-strings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[字符串匹配](../string-matching/README.md)]  | Hard |
-| 1396 | [设计地铁系统](../../problems/design-underground-system) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1392 | [最长快乐前缀](../../problems/longest-happy-prefix) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1374 | [生成每种字符都是奇数个的字符串](../../problems/generate-a-string-with-characters-that-have-odd-counts) | [[字符串](../string/README.md)]  | Easy |
-| 1371 | [每个元音包含偶数次的最长子字符串](../../problems/find-the-longest-substring-containing-vowels-in-even-counts) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1370 | [上升下降字符串](../../problems/increasing-decreasing-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1366 | [通过投票对团队排名](../../problems/rank-teams-by-votes) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1360 | [日期之间隔几天](../../problems/number-of-days-between-two-dates) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1358 | [包含所有三种字符的子字符串数目](../../problems/number-of-substrings-containing-all-three-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1347 | [制造字母异位词的最小步骤数](../../problems/minimum-number-of-steps-to-make-two-strings-anagram) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1332 | [删除回文子序列](../../problems/remove-palindromic-subsequences) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1328 | [破坏回文串](../../problems/break-a-palindrome) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1324 | [竖直打印单词](../../problems/print-words-vertically) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1320 | [二指输入的的最小距离](../../problems/minimum-distance-to-type-a-word-using-two-fingers) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1316 | [不同的循环子字符串](../../problems/distinct-echo-substrings) | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1312 | [让字符串成为回文串的最少插入次数](../../problems/minimum-insertion-steps-to-make-a-string-palindrome) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1309 | [解码字母到整数映射](../../problems/decrypt-string-from-alphabet-to-integer-mapping) | [[字符串](../string/README.md)]  | Easy |
-| 1307 | [口算难题](../../problems/verbal-arithmetic-puzzle) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1297 | [子串的最大出现次数](../../problems/maximum-number-of-occurrences-of-a-substring) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1286 | [字母组合迭代器](../../problems/iterator-for-combination) | [[设计](../design/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 1278 | [分割回文串 III](../../problems/palindrome-partitioning-iii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1271 | [十六进制魔术数字](../../problems/hexspeak) 🔒 | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1268 | [搜索推荐系统](../../problems/search-suggestions-system) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1258 | [近义词句子](../../problems/synonymous-sentences) 🔒 | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1257 | [最小公共区域](../../problems/smallest-common-region) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1256 | [加密数字](../../problems/encode-number) 🔒 | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1255 | [得分最高的单词集合](../../problems/maximum-score-words-formed-by-letters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1249 | [移除无效的括号](../../problems/minimum-remove-to-make-valid-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1247 | [交换字符使得字符串相同](../../problems/minimum-swaps-to-make-strings-equal) | [[贪心](../greedy/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1239 | [串联字符串的最大长度](../../problems/maximum-length-of-a-concatenated-string-with-unique-characters) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1236 | [网络爬虫](../../problems/web-crawler) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1234 | [替换子串得到平衡字符串](../../problems/replace-the-substring-for-balanced-string) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1233 | [删除子文件夹](../../problems/remove-sub-folders-from-the-filesystem) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1221 | [分割平衡字符串](../../problems/split-a-string-in-balanced-strings) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1216 | [验证回文字符串 III](../../problems/valid-palindrome-iii) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1209 | [删除字符串中的所有相邻重复项 II](../../problems/remove-all-adjacent-duplicates-in-string-ii) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1208 | [尽可能使字符串相等](../../problems/get-equal-substrings-within-budget) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1202 | [交换字符串中的元素](../../problems/smallest-string-with-swaps) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1190 | [反转每对括号间的子串](../../problems/reverse-substrings-between-each-pair-of-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1189 | [“气球” 的最大数量](../../problems/maximum-number-of-balloons) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 1181 | [前后拼接](../../problems/before-and-after-puzzle) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1180 | [统计只含单一字母的子串](../../problems/count-substrings-with-only-one-distinct-letter) 🔒 | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1178 | [猜字谜](../../problems/number-of-valid-words-for-each-puzzle) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1177 | [构建回文串检测](../../problems/can-make-palindrome-from-substring) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1170 | [比较字符串最小字母出现频次](../../problems/compare-strings-by-frequency-of-the-smallest-character) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1169 | [查询无效交易](../../problems/invalid-transactions) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1166 | [设计文件系统](../../problems/design-file-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1165 | [单行键盘](../../problems/single-row-keyboard) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1163 | [按字典序排在最后的子串](../../problems/last-substring-in-lexicographical-order) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1160 | [拼写单词](../../problems/find-words-that-can-be-formed-by-characters) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1156 | [单字符重复子串的最大长度](../../problems/swap-for-longest-repeated-character-substring) | [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1154 | [一年中的第几天](../../problems/day-of-the-year) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1153 | [字符串转化](../../problems/string-transforms-into-another-string) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1147 | [段式回文](../../problems/longest-chunked-palindrome-decomposition) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1143 | [最长公共子序列](../../problems/longest-common-subsequence) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1138 | [字母板上的路径](../../problems/alphabet-board-path) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1119 | [删去字符串中的元音](../../problems/remove-vowels-from-a-string) 🔒 | [[字符串](../string/README.md)]  | Easy |
-| 1111 | [有效括号的嵌套深度](../../problems/maximum-nesting-depth-of-two-valid-parentheses-strings) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1108 | [IP 地址无效化](../../problems/defanging-an-ip-address) | [[字符串](../string/README.md)]  | Easy |
-| 1106 | [解析布尔表达式](../../problems/parsing-a-boolean-expression) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1100 | [长度为 K 的无重复字符子串](../../problems/find-k-length-substrings-with-no-repeated-characters) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 1096 | [花括号展开 II](../../problems/brace-expansion-ii) | [[栈](../stack/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 1092 | [最短公共超序列](../../problems/shortest-common-supersequence) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1087 | [花括号展开](../../problems/brace-expansion) 🔒 | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1081 | [不同字符的最小子序列](../../problems/smallest-subsequence-of-distinct-characters) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1079 | [活字印刷](../../problems/letter-tile-possibilities) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1078 | [Bigram 分词](../../problems/occurrences-after-bigram) | [[字符串](../string/README.md)]  | Easy |
-| 1071 | [字符串的最大公因子](../../problems/greatest-common-divisor-of-strings) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1065 | [字符串的索引对](../../problems/index-pairs-of-a-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1062 | [最长重复子串](../../problems/longest-repeating-substring) 🔒 | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1061 | [按字典序排列最小的等效字符串](../../problems/lexicographically-smallest-equivalent-string) 🔒 | [[并查集](../union-find/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1058 | [最小化舍入误差以满足目标](../../problems/minimize-rounding-error-to-meet-target) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1055 | [形成字符串的最短路径](../../problems/shortest-way-to-form-string) 🔒 | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1048 | [最长字符串链](../../problems/longest-string-chain) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1047 | [删除字符串中的所有相邻重复项](../../problems/remove-all-adjacent-duplicates-in-string) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1044 | [最长重复子串](../../problems/longest-duplicate-substring) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1041 | [困于环中的机器人](../../problems/robot-bounded-in-circle) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 1032 | [字符流](../../problems/stream-of-characters) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[数据流](../data-stream/README.md)]  | Hard |
-| 1028 | [从先序遍历还原二叉树](../../problems/recover-a-tree-from-preorder-traversal) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1023 | [驼峰式匹配](../../problems/camelcase-matching) | [[字典树](../trie/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 1021 | [删除最外层的括号](../../problems/remove-outermost-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1016 | [子串能表示从 1 到 N 数字的二进制串](../../problems/binary-string-with-substrings-representing-1-to-n) | [[字符串](../string/README.md)]  | Medium |
-| 1003 | [检查替换后的词是否有效](../../problems/check-if-word-is-valid-after-substitutions) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1002 | [查找共用字符](../../problems/find-common-characters) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 990 | [等式方程的可满足性](../../problems/satisfiability-of-equality-equations) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 988 | [从叶结点开始的最小字符串](../../problems/smallest-string-starting-from-leaf) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 984 | [不含 AAA 或 BBB 的字符串](../../problems/string-without-aaa-or-bbb) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 981 | [基于时间的键值存储](../../problems/time-based-key-value-store) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 972 | [相等的有理数](../../problems/equal-rational-numbers) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 966 | [元音拼写检查器](../../problems/vowel-spellchecker) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 960 | [删列造序 III](../../problems/delete-columns-to-make-sorted-iii) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 955 | [删列造序 II](../../problems/delete-columns-to-make-sorted-ii) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 953 | [验证外星语词典](../../problems/verifying-an-alien-dictionary) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 949 | [给定数字能组成的最大时间](../../problems/largest-time-for-given-digits) | [[字符串](../string/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 944 | [删列造序](../../problems/delete-columns-to-make-sorted) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 943 | [最短超级串](../../problems/find-the-shortest-superstring) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 942 | [增减字符串匹配](../../problems/di-string-match) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 940 | [不同的子序列 II](../../problems/distinct-subsequences-ii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 937 | [重新排列日志文件](../../problems/reorder-data-in-log-files) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 936 | [戳印序列](../../problems/stamping-the-sequence) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 929 | [独特的电子邮件地址](../../problems/unique-email-addresses) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 926 | [将字符串翻转到单调递增](../../problems/flip-string-to-monotone-increasing) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 925 | [长按键入](../../problems/long-pressed-name) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 921 | [使括号有效的最少添加](../../problems/minimum-add-to-make-parentheses-valid) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 917 | [仅仅反转字母](../../problems/reverse-only-letters) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 916 | [单词子集](../../problems/word-subsets) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 899 | [有序队列](../../problems/orderly-queue) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 893 | [特殊等价字符串组](../../problems/groups-of-special-equivalent-strings) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 890 | [查找和替换模式](../../problems/find-and-replace-pattern) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 884 | [两句话中的不常见单词](../../problems/uncommon-words-from-two-sentences) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 880 | [索引处的解码字符串](../../problems/decoded-string-at-index) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 859 | [亲密字符串](../../problems/buddy-strings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 856 | [括号的分数](../../problems/score-of-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 854 | [相似度为 K 的字符串](../../problems/k-similar-strings) | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 848 | [字母移位](../../problems/shifting-letters) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 844 | [比较含退格的字符串](../../problems/backspace-string-compare) | [[栈](../stack/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 843 | [猜猜这个单词](../../problems/guess-the-word) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[博弈](../game-theory/README.md)] [[交互](../interactive/README.md)]  | Hard |
-| 842 | [将数组拆分成斐波那契序列](../../problems/split-array-into-fibonacci-sequence) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 839 | [相似字符串组](../../problems/similar-string-groups) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 838 | [推多米诺](../../problems/push-dominoes) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 833 | [字符串中的查找与替换](../../problems/find-and-replace-in-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 831 | [隐藏个人信息](../../problems/masking-personal-information) | [[字符串](../string/README.md)]  | Medium |
-| 830 | [较大分组的位置](../../problems/positions-of-large-groups) | [[字符串](../string/README.md)]  | Easy |
-| 828 | [统计子串中的唯一字符](../../problems/count-unique-characters-of-all-substrings-of-a-given-string) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 824 | [山羊拉丁文](../../problems/goat-latin) | [[字符串](../string/README.md)]  | Easy |
-| 821 | [字符的最短距离](../../problems/shortest-distance-to-a-character) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 820 | [单词的压缩编码](../../problems/short-encoding-of-words) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 819 | [最常见的单词](../../problems/most-common-word) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 816 | [模糊坐标](../../problems/ambiguous-coordinates) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 811 | [子域名访问计数](../../problems/subdomain-visit-count) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 809 | [情感丰富的文字](../../problems/expressive-words) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 806 | [写字符串需要的行数](../../problems/number-of-lines-to-write-string) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 804 | [唯一摩尔斯密码词](../../problems/unique-morse-code-words) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 800 | [相似 RGB 颜色](../../problems/similar-rgb-color) 🔒 | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[枚举](../enumeration/README.md)]  | Easy |
-| 796 | [旋转字符串](../../problems/rotate-string) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 794 | [有效的井字游戏](../../problems/valid-tic-tac-toe-state) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 792 | [匹配子序列的单词数](../../problems/number-of-matching-subsequences) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 791 | [自定义字符串排序](../../problems/custom-sort-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 784 | [字母大小写全排列](../../problems/letter-case-permutation) | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 777 | [在LR字符串中交换相邻字符](../../problems/swap-adjacent-in-lr-string) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 772 | [基本计算器 III](../../problems/basic-calculator-iii) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 771 | [宝石与石头](../../problems/jewels-and-stones) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 770 | [基本计算器 IV](../../problems/basic-calculator-iv) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 767 | [重构字符串](../../problems/reorganize-string) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 763 | [划分字母区间](../../problems/partition-labels) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 761 | [特殊的二进制序列](../../problems/special-binary-string) | [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 758 | [字符串中的加粗单词](../../problems/bold-words-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 752 | [打开转盘锁](../../problems/open-the-lock) | [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 751 | [IP 到 CIDR](../../problems/ip-to-cidr) 🔒 | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 748 | [最短补全词](../../problems/shortest-completing-word) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 745 | [前缀和后缀搜索](../../problems/prefix-and-suffix-search) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 737 | [句子相似性 II](../../problems/sentence-similarity-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 736 | [Lisp 语法解析](../../problems/parse-lisp-expression) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 734 | [句子相似性](../../problems/sentence-similarity) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 730 | [统计不同回文子序列](../../problems/count-different-palindromic-subsequences) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 727 | [最小窗口子序列](../../problems/minimum-window-subsequence) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 726 | [原子的数量](../../problems/number-of-atoms) | [[栈](../stack/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 722 | [删除注释](../../problems/remove-comments) | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 721 | [账户合并](../../problems/accounts-merge) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 720 | [词典中最长的单词](../../problems/longest-word-in-dictionary) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 712 | [两个字符串的最小ASCII删除和](../../problems/minimum-ascii-delete-sum-for-two-strings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 709 | [转换成小写字母](../../problems/to-lower-case) | [[字符串](../string/README.md)]  | Easy |
-| 696 | [计数二进制子串](../../problems/count-binary-substrings) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 692 | [前K个高频单词](../../problems/top-k-frequent-words) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 686 | [重复叠加字符串匹配](../../problems/repeated-string-match) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 681 | [最近时刻](../../problems/next-closest-time) 🔒 | [[字符串](../string/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 680 | [验证回文字符串 Ⅱ](../../problems/valid-palindrome-ii) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 678 | [有效的括号字符串](../../problems/valid-parenthesis-string) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 677 | [键值映射](../../problems/map-sum-pairs) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 676 | [实现一个魔法字典](../../problems/implement-magic-dictionary) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 664 | [奇怪的打印机](../../problems/strange-printer) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 657 | [机器人能否返回原点](../../problems/robot-return-to-origin) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 649 | [Dota2 参议院](../../problems/dota2-senate) | [[贪心](../greedy/README.md)] [[队列](../queue/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 648 | [单词替换](../../problems/replace-words) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 647 | [回文子串](../../problems/palindromic-substrings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 642 | [设计搜索自动补全系统](../../problems/design-search-autocomplete-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[数据流](../data-stream/README.md)]  | Hard |
-| 640 | [求解方程](../../problems/solve-the-equation) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 639 | [解码方法 II](../../problems/decode-ways-ii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 635 | [设计日志存储系统](../../problems/design-log-storage-system) 🔒 | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 616 | [给字符串添加加粗标签](../../problems/add-bold-tag-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 609 | [在系统中查找重复文件](../../problems/find-duplicate-file-in-system) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 606 | [根据二叉树创建字符串](../../problems/construct-string-from-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 604 | [迭代压缩字符串](../../problems/design-compressed-string-iterator) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[迭代器](../iterator/README.md)]  | Easy |
-| 599 | [两个列表的最小索引总和](../../problems/minimum-index-sum-of-two-lists) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 592 | [分数加减运算](../../problems/fraction-addition-and-subtraction) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 591 | [标签验证器](../../problems/tag-validator) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 588 | [设计内存文件系统](../../problems/design-in-memory-file-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 583 | [两个字符串的删除操作](../../problems/delete-operation-for-two-strings) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 567 | [字符串的排列](../../problems/permutation-in-string) | [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 564 | [寻找最近的回文数](../../problems/find-the-closest-palindrome) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 557 | [反转字符串中的单词 III](../../problems/reverse-words-in-a-string-iii) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 556 | [下一个更大元素 III](../../problems/next-greater-element-iii) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 555 | [分割连接字符串](../../problems/split-concatenated-strings) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 551 | [学生出勤记录 I](../../problems/student-attendance-record-i) | [[字符串](../string/README.md)]  | Easy |
-| 544 | [输出比赛匹配对](../../problems/output-contest-matches) 🔒 | [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 541 | [反转字符串 II](../../problems/reverse-string-ii) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 539 | [最小时间差](../../problems/minimum-time-difference) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 537 | [复数乘法](../../problems/complex-number-multiplication) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 536 | [从字符串生成二叉树](../../problems/construct-binary-tree-from-string) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 535 | [TinyURL 的加密与解密](../../problems/encode-and-decode-tinyurl) | [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)]  | Medium |
-| 527 | [单词缩写](../../problems/word-abbreviation) 🔒 | [[贪心](../greedy/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 524 | [通过删除字母匹配到字典里最长单词](../../problems/longest-word-in-dictionary-through-deleting) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 522 | [最长特殊序列 II](../../problems/longest-uncommon-subsequence-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 521 | [最长特殊序列 Ⅰ](../../problems/longest-uncommon-subsequence-i) | [[字符串](../string/README.md)]  | Easy |
-| 520 | [检测大写字母](../../problems/detect-capital) | [[字符串](../string/README.md)]  | Easy |
-| 516 | [最长回文子序列](../../problems/longest-palindromic-subsequence) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 514 | [自由之路](../../problems/freedom-trail) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 500 | [键盘行](../../problems/keyboard-row) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 488 | [祖玛游戏](../../problems/zuma-game) | [[广度优先搜索](../breadth-first-search/README.md)] [[记忆化搜索](../memoization/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 482 | [密钥格式化](../../problems/license-key-formatting) | [[字符串](../string/README.md)]  | Easy |
-| 481 | [神奇字符串](../../problems/magical-string) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 474 | [一和零](../../problems/ones-and-zeroes) | [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 472 | [连接词](../../problems/concatenated-words) | [[深度优先搜索](../depth-first-search/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 471 | [编码最短长度的字符串](../../problems/encode-string-with-shortest-length) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 468 | [验证IP地址](../../problems/validate-ip-address) | [[字符串](../string/README.md)]  | Medium |
-| 467 | [环绕字符串中唯一的子字符串](../../problems/unique-substrings-in-wraparound-string) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 466 | [统计重复个数](../../problems/count-the-repetitions) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 459 | [重复的子字符串](../../problems/repeated-substring-pattern) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 451 | [根据字符出现频率排序](../../problems/sort-characters-by-frequency) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 449 | [序列化和反序列化二叉搜索树](../../problems/serialize-and-deserialize-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 443 | [压缩字符串](../../problems/string-compression) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 439 | [三元表达式解析器](../../problems/ternary-expression-parser) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 438 | [找到字符串中所有字母异位词](../../problems/find-all-anagrams-in-a-string) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 434 | [字符串中的单词数](../../problems/number-of-segments-in-a-string) | [[字符串](../string/README.md)]  | Easy |
-| 433 | [最小基因变化](../../problems/minimum-genetic-mutation) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 428 | [序列化和反序列化 N 叉树](../../problems/serialize-and-deserialize-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 425 | [单词方块](../../problems/word-squares) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 424 | [替换后的最长重复字符](../../problems/longest-repeating-character-replacement) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 423 | [从英文中重建数字](../../problems/reconstruct-original-digits-from-english) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 420 | [强密码检验器](../../problems/strong-password-checker) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 418 | [屏幕可显示句子的数量](../../problems/sentence-screen-fitting) 🔒 | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 415 | [字符串相加](../../problems/add-strings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 412 | [Fizz Buzz](../../problems/fizz-buzz) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 411 | [最短独占单词缩写](../../problems/minimum-unique-word-abbreviation) 🔒 | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 409 | [最长回文串](../../problems/longest-palindrome) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 408 | [有效单词缩写](../../problems/valid-word-abbreviation) 🔒 | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 402 | [移掉 K 位数字](../../problems/remove-k-digits) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 395 | [至少有 K 个重复字符的最长子串](../../problems/longest-substring-with-at-least-k-repeating-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[分治](../divide-and-conquer/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 394 | [字符串解码](../../problems/decode-string) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 392 | [判断子序列](../../problems/is-subsequence) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 389 | [找不同](../../problems/find-the-difference) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 388 | [文件的最长绝对路径](../../problems/longest-absolute-file-path) | [[栈](../stack/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 387 | [字符串中的第一个唯一字符](../../problems/first-unique-character-in-a-string) | [[队列](../queue/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 385 | [迷你语法分析器](../../problems/mini-parser) | [[栈](../stack/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 383 | [赎金信](../../problems/ransom-note) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Easy |
-| 358 | [K 距离间隔重排字符串](../../problems/rearrange-string-k-distance-apart) 🔒 | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 345 | [反转字符串中的元音字母](../../problems/reverse-vowels-of-a-string) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 344 | [反转字符串](../../problems/reverse-string) | [[递归](../recursion/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 340 | [至多包含 K 个不同字符的最长子串](../../problems/longest-substring-with-at-most-k-distinct-characters) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 336 | [回文对](../../problems/palindrome-pairs) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 331 | [验证二叉树的前序序列化](../../problems/verify-preorder-serialization-of-a-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 320 | [列举单词的全部缩写](../../problems/generalized-abbreviation) 🔒 | [[位运算](../bit-manipulation/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 318 | [最大单词长度乘积](../../problems/maximum-product-of-word-lengths) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 316 | [去除重复字母](../../problems/remove-duplicate-letters) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 306 | [累加数](../../problems/additive-number) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 301 | [删除无效的括号](../../problems/remove-invalid-parentheses) | [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 299 | [猜数字游戏](../../problems/bulls-and-cows) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[计数](../counting/README.md)]  | Medium |
-| 297 | [二叉树的序列化与反序列化](../../problems/serialize-and-deserialize-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 293 | [翻转游戏](../../problems/flip-game) 🔒 | [[字符串](../string/README.md)]  | Easy |
-| 291 | [单词规律 II](../../problems/word-pattern-ii) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 290 | [单词规律](../../problems/word-pattern) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 288 | [单词的唯一缩写](../../problems/unique-word-abbreviation) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 282 | [给表达式添加运算符](../../problems/expression-add-operators) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 273 | [整数转换英文表示](../../problems/integer-to-english-words) | [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 271 | [字符串的编码与解码](../../problems/encode-and-decode-strings) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 269 | [火星词典](../../problems/alien-dictionary) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 267 | [回文排列 II](../../problems/palindrome-permutation-ii) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 266 | [回文排列](../../problems/palindrome-permutation) 🔒 | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 257 | [二叉树的所有路径](../../problems/binary-tree-paths) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 249 | [移位字符串分组](../../problems/group-shifted-strings) 🔒 | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 248 | [中心对称数 III](../../problems/strobogrammatic-number-iii) 🔒 | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 247 | [中心对称数 II](../../problems/strobogrammatic-number-ii) 🔒 | [[递归](../recursion/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 246 | [中心对称数](../../problems/strobogrammatic-number) 🔒 | [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 245 | [最短单词距离 III](../../problems/shortest-word-distance-iii) 🔒 | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 244 | [最短单词距离 II](../../problems/shortest-word-distance-ii) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 243 | [最短单词距离](../../problems/shortest-word-distance) 🔒 | [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 242 | [有效的字母异位词](../../problems/valid-anagram) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 241 | [为运算表达式设计优先级](../../problems/different-ways-to-add-parentheses) | [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 227 | [基本计算器 II](../../problems/basic-calculator-ii) | [[栈](../stack/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 224 | [基本计算器](../../problems/basic-calculator) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 214 | [最短回文串](../../problems/shortest-palindrome) | [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 212 | [单词搜索 II](../../problems/word-search-ii) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 211 | [添加与搜索单词 - 数据结构设计](../../problems/design-add-and-search-words-data-structure) | [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 208 | [实现 Trie (前缀树)](../../problems/implement-trie-prefix-tree) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 205 | [同构字符串](../../problems/isomorphic-strings) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 187 | [重复的DNA序列](../../problems/repeated-dna-sequences) | [[位运算](../bit-manipulation/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 186 | [翻转字符串里的单词 II](../../problems/reverse-words-in-a-string-ii) 🔒 | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 179 | [最大数](../../problems/largest-number) | [[贪心](../greedy/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 171 | [Excel 表列序号](../../problems/excel-sheet-column-number) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 168 | [Excel表列名称](../../problems/excel-sheet-column-title) | [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 166 | [分数到小数](../../problems/fraction-to-recurring-decimal) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 165 | [比较版本号](../../problems/compare-version-numbers) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 161 | [相隔为 1 的编辑距离](../../problems/one-edit-distance) 🔒 | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 159 | [至多包含两个不同字符的最长子串](../../problems/longest-substring-with-at-most-two-distinct-characters) 🔒 | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 158 | [用 Read4 读取 N 个字符 II](../../problems/read-n-characters-given-read4-ii-call-multiple-times) 🔒 | [[字符串](../string/README.md)] [[交互](../interactive/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 157 | [用 Read4 读取 N 个字符](../../problems/read-n-characters-given-read4) 🔒 | [[字符串](../string/README.md)] [[交互](../interactive/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 151 | [翻转字符串里的单词](../../problems/reverse-words-in-a-string) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 140 | [单词拆分 II](../../problems/word-break-ii) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 139 | [单词拆分](../../problems/word-break) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 132 | [分割回文串 II](../../problems/palindrome-partitioning-ii) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 131 | [分割回文串](../../problems/palindrome-partitioning) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 127 | [单词接龙](../../problems/word-ladder) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 126 | [单词接龙 II](../../problems/word-ladder-ii) | [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 125 | [验证回文串](../../problems/valid-palindrome) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 115 | [不同的子序列](../../problems/distinct-subsequences) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 97 | [交错字符串](../../problems/interleaving-string) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 93 | [复原 IP 地址](../../problems/restore-ip-addresses) | [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 91 | [解码方法](../../problems/decode-ways) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 87 | [扰乱字符串](../../problems/scramble-string) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 76 | [最小覆盖子串](../../problems/minimum-window-substring) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 72 | [编辑距离](../../problems/edit-distance) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 71 | [简化路径](../../problems/simplify-path) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 68 | [文本左右对齐](../../problems/text-justification) | [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Hard |
-| 67 | [二进制求和](../../problems/add-binary) | [[位运算](../bit-manipulation/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 65 | [有效数字](../../problems/valid-number) | [[字符串](../string/README.md)]  | Hard |
-| 58 | [最后一个单词的长度](../../problems/length-of-last-word) | [[字符串](../string/README.md)]  | Easy |
-| 49 | [字母异位词分组](../../problems/group-anagrams) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 44 | [通配符匹配](../../problems/wildcard-matching) | [[贪心](../greedy/README.md)] [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 43 | [字符串相乘](../../problems/multiply-strings) | [[数学](../math/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 38 | [外观数列](../../problems/count-and-say) | [[字符串](../string/README.md)]  | Medium |
-| 32 | [最长有效括号](../../problems/longest-valid-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 30 | [串联所有单词的子串](../../problems/substring-with-concatenation-of-all-words) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Hard |
-| 28 | [实现 strStr()](../../problems/implement-strstr) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 22 | [括号生成](../../problems/generate-parentheses) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 20 | [有效的括号](../../problems/valid-parentheses) | [[栈](../stack/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 17 | [电话号码的字母组合](../../problems/letter-combinations-of-a-phone-number) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 14 | [最长公共前缀](../../problems/longest-common-prefix) | [[字符串](../string/README.md)]  | Easy |
-| 13 | [罗马数字转整数](../../problems/roman-to-integer) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 12 | [整数转罗马数字](../../problems/integer-to-roman) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 10 | [正则表达式匹配](../../problems/regular-expression-matching) | [[递归](../recursion/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 8 | [字符串转换整数 (atoi)](../../problems/string-to-integer-atoi) | [[字符串](../string/README.md)]  | Medium |
-| 6 | [Z 字形变换](../../problems/zigzag-conversion) | [[字符串](../string/README.md)]  | Medium |
-| 5 | [最长回文子串](../../problems/longest-palindromic-substring) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 3 | [无重复字符的最长子串](../../problems/longest-substring-without-repeating-characters) | [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
diff --git a/tag/strongly-connected-component/README.md b/tag/strongly-connected-component/README.md
deleted file mode 100644
index 10e0277ac..000000000
--- a/tag/strongly-connected-component/README.md
+++ /dev/null
@@ -1,13 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 强连通分量
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1568 | [使陆地分离的最少天数](../../problems/minimum-number-of-days-to-disconnect-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
-| 1489 | [找到最小生成树里的关键边和伪关键边](../../problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)] [[排序](../sorting/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
diff --git a/tag/suffix-array/README.md b/tag/suffix-array/README.md
deleted file mode 100644
index de556bab0..000000000
--- a/tag/suffix-array/README.md
+++ /dev/null
@@ -1,16 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 后缀数组
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1977 | [划分数字的方案数](../../problems/number-of-ways-to-separate-numbers) | [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[后缀数组](../suffix-array/README.md)]  | Hard |
-| 1923 | [最长公共子路径](../../problems/longest-common-subpath) | [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1698 | [字符串的不同子字符串个数](../../problems/number-of-distinct-substrings-in-a-string) 🔒 | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1062 | [最长重复子串](../../problems/longest-repeating-substring) 🔒 | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1044 | [最长重复子串](../../problems/longest-duplicate-substring) | [[字符串](../string/README.md)] [[二分查找](../binary-search/README.md)] [[后缀数组](../suffix-array/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
diff --git a/tag/tags.js b/tag/tags.js
deleted file mode 100644
index f5c8f0b77..000000000
--- a/tag/tags.js
+++ /dev/null
@@ -1,11 +0,0 @@
-tags = [];
-document.querySelectorAll('#all-topic-tags>a').forEach(function (e) {
-    tags.push({
-        "Name": e.title || e.firstElementChild.innerText.trim(),
-        "Slug": /tag\/(\S+?)\//.exec(e.href)[1],
-        "TranslatedName": e.innerText.trim().replace(/\n/g, ''),
-    });
-});
-newWindow = window.open('', 'frame_name');
-newWindow.document.write(JSON.stringify(tags));
-newWindow.document.close();
diff --git a/tag/tags.json b/tag/tags.json
deleted file mode 100644
index a05a8218f..000000000
--- a/tag/tags.json
+++ /dev/null
@@ -1,387 +0,0 @@
-[
-	{
-		"Name": "Array",
-		"Slug": "array",
-		"TranslatedName": "数组"
-	},
-	{
-		"Name": "Dynamic Programming",
-		"Slug": "dynamic-programming",
-		"TranslatedName": "动态规划"
-	},
-	{
-		"Name": "String",
-		"Slug": "string",
-		"TranslatedName": "字符串"
-	},
-	{
-		"Name": "Math",
-		"Slug": "math",
-		"TranslatedName": "数学"
-	},
-	{
-		"Name": "Greedy",
-		"Slug": "greedy",
-		"TranslatedName": "贪心"
-	},
-	{
-		"Name": "Depth-First Search",
-		"Slug": "depth-first-search",
-		"TranslatedName": "深度优先搜索"
-	},
-	{
-		"Name": "Tree",
-		"Slug": "tree",
-		"TranslatedName": "树"
-	},
-	{
-		"Name": "Hash Table",
-		"Slug": "hash-table",
-		"TranslatedName": "哈希表"
-	},
-	{
-		"Name": "Binary Search",
-		"Slug": "binary-search",
-		"TranslatedName": "二分查找"
-	},
-	{
-		"Name": "Breadth-First Search",
-		"Slug": "breadth-first-search",
-		"TranslatedName": "广度优先搜索"
-	},
-	{
-		"Name": "Sort",
-		"Slug": "sort",
-		"TranslatedName": "排序"
-	},
-	{
-		"Name": "Two Pointers",
-		"Slug": "two-pointers",
-		"TranslatedName": "双指针"
-	},
-	{
-		"Name": "Backtracking",
-		"Slug": "backtracking",
-		"TranslatedName": "回溯"
-	},
-	{
-		"Name": "Design",
-		"Slug": "design",
-		"TranslatedName": "设计"
-	},
-	{
-		"Name": "Stack",
-		"Slug": "stack",
-		"TranslatedName": "栈"
-	},
-	{
-		"Name": "Bit Manipulation",
-		"Slug": "bit-manipulation",
-		"TranslatedName": "位运算"
-	},
-	{
-		"Name": "Graph",
-		"Slug": "graph",
-		"TranslatedName": "图"
-	},
-	{
-		"Name": "Heap",
-		"Slug": "heap",
-		"TranslatedName": "堆"
-	},
-	{
-		"Name": "Linked List",
-		"Slug": "linked-list",
-		"TranslatedName": "链表"
-	},
-	{
-		"Name": "Recursion",
-		"Slug": "recursion",
-		"TranslatedName": "递归"
-	},
-	{
-		"Name": "Union Find",
-		"Slug": "union-find",
-		"TranslatedName": "并查集"
-	},
-	{
-		"Name": "Sliding Window",
-		"Slug": "sliding-window",
-		"TranslatedName": "滑动窗口"
-	},
-	{
-		"Name": "Trie",
-		"Slug": "trie",
-		"TranslatedName": "字典树"
-	},
-	{
-		"Name": "Divide and Conquer",
-		"Slug": "divide-and-conquer",
-		"TranslatedName": "分治"
-	},
-	{
-		"Name": "Ordered Map",
-		"Slug": "ordered-map",
-		"TranslatedName": "Ordered Map"
-	},
-	{
-		"Name": "Segment Tree",
-		"Slug": "segment-tree",
-		"TranslatedName": "线段树"
-	},
-	{
-		"Name": "Queue",
-		"Slug": "queue",
-		"TranslatedName": "队列"
-	},
-	{
-		"Name": "Geometry",
-		"Slug": "geometry",
-		"TranslatedName": "几何"
-	},
-	{
-		"Name": "Line Sweep",
-		"Slug": "line-sweep",
-		"TranslatedName": "扫描线"
-	},
-	{
-		"Name": "Binary Indexed Tree",
-		"Slug": "binary-indexed-tree",
-		"TranslatedName": "树状数组"
-	},
-	{
-		"Name": "Minimax",
-		"Slug": "minimax",
-		"TranslatedName": "极小化极大"
-	},
-	{
-		"Name": "Brainteaser",
-		"Slug": "brainteaser",
-		"TranslatedName": "脑筋急转弯"
-	},
-	{
-		"Name": "Topological Sort",
-		"Slug": "topological-sort",
-		"TranslatedName": "拓扑排序"
-	},
-	{
-		"Name": "Dequeue",
-		"Slug": "dequeue",
-		"TranslatedName": "Dequeue"
-	},
-	{
-		"Name": "Random",
-		"Slug": "random",
-		"TranslatedName": "Random"
-	},
-	{
-		"Name": "Binary Search Tree",
-		"Slug": "binary-search-tree",
-		"TranslatedName": "二叉搜索树"
-	},
-	{
-		"Name": "Rolling Hash",
-		"Slug": "rolling-hash",
-		"TranslatedName": "滚动哈希"
-	},
-	{
-		"Name": "Suffix Array",
-		"Slug": "suffix-array",
-		"TranslatedName": "后缀数组"
-	},
-	{
-		"Name": "Rejection Sampling",
-		"Slug": "rejection-sampling",
-		"TranslatedName": "拒绝采样"
-	},
-	{
-		"Name": "Reservoir Sampling",
-		"Slug": "reservoir-sampling",
-		"TranslatedName": "水塘抽样"
-	},
-	{
-		"Name": "Meet In The Middle",
-		"Slug": "meet-in-the-middle",
-		"TranslatedName": "Meet In The Middle"
-	},
-	{
-		"Name": "Memoization",
-		"Slug": "memoization",
-		"TranslatedName": "记忆化搜索"
-	},
-	{
-		"Name": "OOP",
-		"Slug": "oop",
-		"TranslatedName": "OOP"
-	},
-	{
-		"Name": "Sorting",
-		"Slug": "sorting",
-		"TranslatedName": "排序"
-	},
-	{
-		"Name": "Heap (Priority Queue)",
-		"Slug": "heap-priority-queue",
-		"TranslatedName": "堆（优先队列）"
-	},
-	{
-		"Name": "Ordered Set",
-		"Slug": "ordered-set",
-		"TranslatedName": "有序集合"
-	},
-	{
-		"Name": "Hash Function",
-		"Slug": "hash-function",
-		"TranslatedName": "哈希函数"
-	},
-	{
-		"Name": "String Matching",
-		"Slug": "string-matching",
-		"TranslatedName": "字符串匹配"
-	},
-	{
-		"Name": "Randomized",
-		"Slug": "randomized",
-		"TranslatedName": "随机化"
-	},
-	{
-		"Name": "Prefix Sum",
-		"Slug": "prefix-sum",
-		"TranslatedName": "前缀和"
-	},
-	{
-		"Name": "Probability and Statistics",
-		"Slug": "probability-and-statistics",
-		"TranslatedName": "概率与统计"
-	},
-	{
-		"Name": "Simulation",
-		"Slug": "simulation",
-		"TranslatedName": "模拟"
-	},
-	{
-		"Name": "Monotonic Queue",
-		"Slug": "monotonic-queue",
-		"TranslatedName": "单调队列"
-	},
-	{
-		"Name": "Data Stream",
-		"Slug": "data-stream",
-		"TranslatedName": "数据流"
-	},
-	{
-		"Name": "Counting",
-		"Slug": "counting",
-		"TranslatedName": "计数"
-	},
-	{
-		"Name": "Matrix",
-		"Slug": "matrix",
-		"TranslatedName": "矩阵"
-	},
-	{
-		"Name": "Iterator",
-		"Slug": "iterator",
-		"TranslatedName": "迭代器"
-	},
-	{
-		"Name": "Quickselect",
-		"Slug": "quickselect",
-		"TranslatedName": "快速选择"
-	},
-	{
-		"Name": "Merge Sort",
-		"Slug": "merge-sort",
-		"TranslatedName": "归并排序"
-	},
-	{
-		"Name": "Binary Tree",
-		"Slug": "binary-tree",
-		"TranslatedName": "二叉树"
-	},
-	{
-		"Name": "Combinatorics",
-		"Slug": "combinatorics",
-		"TranslatedName": "组合数学"
-	},
-	{
-		"Name": "Shortest Path",
-		"Slug": "shortest-path",
-		"TranslatedName": "最短路"
-	},
-	{
-		"Name": "Interactive",
-		"Slug": "interactive",
-		"TranslatedName": "交互"
-	},
-	{
-		"Name": "Bucket Sort",
-		"Slug": "bucket-sort",
-		"TranslatedName": "桶排序"
-	},
-	{
-		"Name": "Counting Sort",
-		"Slug": "counting-sort",
-		"TranslatedName": "计数排序"
-	},
-	{
-		"Name": "Radix Sort",
-		"Slug": "radix-sort",
-		"TranslatedName": "基数排序"
-	},
-	{
-		"Name": "Monotonic Stack",
-		"Slug": "monotonic-stack",
-		"TranslatedName": "单调栈"
-	},
-	{
-		"Name": "Minimum Spanning Tree",
-		"Slug": "minimum-spanning-tree",
-		"TranslatedName": "最小生成树"
-	},
-	{
-		"Name": "Strongly Connected Component",
-		"Slug": "strongly-connected-component",
-		"TranslatedName": "强连通分量"
-	},
-	{
-		"Name": "Game Theory",
-		"Slug": "game-theory",
-		"TranslatedName": "博弈"
-	},
-	{
-		"Name": "Bitmask",
-		"Slug": "bitmask",
-		"TranslatedName": "状态压缩"
-	},
-	{
-		"Name": "Concurrency",
-		"Slug": "concurrency",
-		"TranslatedName": "多线程"
-	},
-	{
-		"Name": "Doubly-Linked List",
-		"Slug": "doubly-linked-list",
-		"TranslatedName": "双向链表"
-	},
-	{
-		"Name": "Enumeration",
-		"Slug": "enumeration",
-		"TranslatedName": "枚举"
-	},
-	{
-		"Name": "Number Theory",
-		"Slug": "number-theory",
-		"TranslatedName": "数论"
-	},
-	{
-		"Name": "Biconnected Component",
-		"Slug": "biconnected-component",
-		"TranslatedName": "双连通分量"
-	},
-	{
-		"Name": "Eulerian Circuit",
-		"Slug": "eulerian-circuit",
-		"TranslatedName": "欧拉回路"
-	}
-]
\ No newline at end of file
diff --git a/tag/topological-sort/README.md b/tag/topological-sort/README.md
deleted file mode 100644
index eddfb8658..000000000
--- a/tag/topological-sort/README.md
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 拓扑排序
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2127 | [参加会议的最多员工数](../../problems/maximum-employees-to-be-invited-to-a-meeting) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 2115 | [从给定原材料中找到所有可以做出的菜](../../problems/find-all-possible-recipes-from-given-supplies) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 2050 | [并行课程 III](../../problems/parallel-courses-iii) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1976 | [到达目的地的方案数](../../problems/number-of-ways-to-arrive-at-destination) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 1916 | [统计为蚁群构筑房间的不同顺序](../../problems/count-ways-to-build-rooms-in-an-ant-colony) | [[树](../tree/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1857 | [有向图中最大颜色值](../../problems/largest-color-value-in-a-directed-graph) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[动态规划](../dynamic-programming/README.md)] [[计数](../counting/README.md)]  | Hard |
-| 1786 | [从第一个节点出发到最后一个节点的受限路径数](../../problems/number-of-restricted-paths-from-first-to-last-node) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[动态规划](../dynamic-programming/README.md)] [[最短路](../shortest-path/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1719 | [重构一棵树的方案数](../../problems/number-of-ways-to-reconstruct-a-tree) | [[树](../tree/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 1632 | [矩阵转换后的秩](../../problems/rank-transform-of-a-matrix) | [[贪心](../greedy/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1591 | [奇怪的打印机 II](../../problems/strange-printer-ii) | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1462 | [课程表 IV](../../problems/course-schedule-iv) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 1203 | [项目管理](../../problems/sort-items-by-groups-respecting-dependencies) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 1136 | [平行课程](../../problems/parallel-courses) 🔒 | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 851 | [喧闹和富有](../../problems/loud-and-rich) | [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)]  | Medium |
-| 802 | [找到最终的安全状态](../../problems/find-eventual-safe-states) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 631 | [设计 Excel 求和公式](../../problems/design-excel-sum-formula) 🔒 | [[图](../graph/README.md)] [[设计](../design/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 444 | [序列重建](../../problems/sequence-reconstruction) 🔒 | [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)]  | Medium |
-| 329 | [矩阵中的最长递增路径](../../problems/longest-increasing-path-in-a-matrix) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 310 | [最小高度树](../../problems/minimum-height-trees) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 269 | [火星词典](../../problems/alien-dictionary) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 210 | [课程表 II](../../problems/course-schedule-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
-| 207 | [课程表](../../problems/course-schedule) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Medium |
diff --git a/tag/tree/README.md b/tag/tree/README.md
deleted file mode 100644
index 6db216719..000000000
--- a/tag/tree/README.md
+++ /dev/null
@@ -1,193 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 树
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2096 | [从二叉树一个节点到另一个节点每一步的方向](../../problems/step-by-step-directions-from-a-binary-tree-node-to-another) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 2049 | [统计最高分的节点数目](../../problems/count-nodes-with-the-highest-score) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 2003 | [每棵子树内缺失的最小基因值](../../problems/smallest-missing-genetic-value-in-each-subtree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1993 | [树上的操作](../../problems/operations-on-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1932 | [合并多棵二叉搜索树](../../problems/merge-bsts-to-create-single-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1916 | [统计为蚁群构筑房间的不同顺序](../../problems/count-ways-to-build-rooms-in-an-ant-colony) | [[树](../tree/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1902 | [给定二叉搜索树的插入顺序求深度](../../problems/depth-of-bst-given-insertion-order) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[有序集合](../ordered-set/README.md)]  | Medium |
-| 1766 | [互质树](../../problems/tree-of-coprimes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1740 | [找到二叉树中的距离](../../problems/find-distance-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1719 | [重构一棵树的方案数](../../problems/number-of-ways-to-reconstruct-a-tree) | [[树](../tree/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)]  | Hard |
-| 1676 | [二叉树的最近公共祖先 IV](../../problems/lowest-common-ancestor-of-a-binary-tree-iv) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1666 | [改变二叉树的根节点](../../problems/change-the-root-of-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1660 | [纠正二叉树](../../problems/correct-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1650 | [二叉树的最近公共祖先 III](../../problems/lowest-common-ancestor-of-a-binary-tree-iii) 🔒 | [[树](../tree/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1644 | [二叉树的最近公共祖先 II](../../problems/lowest-common-ancestor-of-a-binary-tree-ii) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1628 | [设计带解析函数的表达式树](../../problems/design-an-expression-tree-with-evaluate-function) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[数学](../math/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1617 | [统计子树中城市之间最大距离](../../problems/count-subtrees-with-max-distance-between-cities) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[枚举](../enumeration/README.md)]  | Hard |
-| 1612 | [检查两棵二叉表达式树是否等价](../../problems/check-if-two-expression-trees-are-equivalent) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1609 | [奇偶树](../../problems/even-odd-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1602 | [找到二叉树中最近的右侧节点](../../problems/find-nearest-right-node-in-binary-tree) 🔒 | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1600 | [皇位继承顺序](../../problems/throne-inheritance) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1597 | [根据中缀表达式构造二叉表达式树](../../problems/build-binary-expression-tree-from-infix-expression) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1586 | [二叉搜索树迭代器 II](../../problems/binary-search-tree-iterator-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1530 | [好叶子节点对的数量](../../problems/number-of-good-leaf-nodes-pairs) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1522 | [N 叉树的直径](../../problems/diameter-of-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Medium |
-| 1519 | [子树中标签相同的节点数](../../problems/number-of-nodes-in-the-sub-tree-with-the-same-label) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1516 | [移动 N 叉树的子树](../../problems/move-sub-tree-of-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Hard |
-| 1506 | [找到 N 叉树的根节点](../../problems/find-root-of-n-ary-tree) 🔒 | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1490 | [克隆 N 叉树](../../problems/clone-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1485 | [克隆含随机指针的二叉树](../../problems/clone-binary-tree-with-random-pointer) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1483 | [树节点的第 K 个祖先](../../problems/kth-ancestor-of-a-tree-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1469 | [寻找所有的独生节点](../../problems/find-all-the-lonely-nodes) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 1457 | [二叉树中的伪回文路径](../../problems/pseudo-palindromic-paths-in-a-binary-tree) | [[位运算](../bit-manipulation/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1448 | [统计二叉树中好节点的数目](../../problems/count-good-nodes-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1443 | [收集树上所有苹果的最少时间](../../problems/minimum-time-to-collect-all-apples-in-a-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 1430 | [判断给定的序列是否是二叉树从根到叶的路径](../../problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1382 | [将二叉搜索树变平衡](../../problems/balance-a-binary-search-tree) | [[贪心](../greedy/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1379 | [找出克隆二叉树中的相同节点](../../problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1377 | [T 秒后青蛙的位置](../../problems/frog-position-after-t-seconds) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[图](../graph/README.md)]  | Hard |
-| 1376 | [通知所有员工所需的时间](../../problems/time-needed-to-inform-all-employees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1373 | [二叉搜索子树的最大键值和](../../problems/maximum-sum-bst-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1372 | [二叉树中的最长交错路径](../../problems/longest-zigzag-path-in-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1367 | [二叉树中的列表](../../problems/linked-list-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1361 | [验证二叉树](../../problems/validate-binary-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1339 | [分裂二叉树的最大乘积](../../problems/maximum-product-of-splitted-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1325 | [删除给定值的叶子节点](../../problems/delete-leaves-with-a-given-value) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1315 | [祖父节点值为偶数的节点和](../../problems/sum-of-nodes-with-even-valued-grandparent) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1305 | [两棵二叉搜索树中的所有元素](../../problems/all-elements-in-two-binary-search-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1302 | [层数最深叶子节点的和](../../problems/deepest-leaves-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1273 | [删除树节点](../../problems/delete-tree-nodes) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1261 | [在受污染的二叉树中查找元素](../../problems/find-elements-in-a-contaminated-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1257 | [最小公共区域](../../problems/smallest-common-region) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1245 | [树的直径](../../problems/tree-diameter) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 1214 | [查找两棵二叉搜索树之和](../../problems/two-sum-bsts) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1161 | [最大层内元素和](../../problems/maximum-level-sum-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1145 | [二叉树着色游戏](../../problems/binary-tree-coloring-game) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1123 | [最深叶节点的最近公共祖先](../../problems/lowest-common-ancestor-of-deepest-leaves) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1120 | [子树的最大平均值](../../problems/maximum-average-subtree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1110 | [删点成林](../../problems/delete-nodes-and-return-forest) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1104 | [二叉树寻路](../../problems/path-in-zigzag-labelled-binary-tree) | [[树](../tree/README.md)] [[数学](../math/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1080 | [根到叶路径上的不足节点](../../problems/insufficient-nodes-in-root-to-leaf-paths) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1038 | [把二叉搜索树转换为累加树](../../problems/binary-search-tree-to-greater-sum-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1028 | [从先序遍历还原二叉树](../../problems/recover-a-tree-from-preorder-traversal) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 1026 | [节点与其祖先之间的最大差值](../../problems/maximum-difference-between-node-and-ancestor) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1022 | [从根到叶的二进制数之和](../../problems/sum-of-root-to-leaf-binary-numbers) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 1008 | [前序遍历构造二叉搜索树](../../problems/construct-binary-search-tree-from-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 998 | [最大二叉树 II](../../problems/maximum-binary-tree-ii) | [[树](../tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 993 | [二叉树的堂兄弟节点](../../problems/cousins-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 988 | [从叶结点开始的最小字符串](../../problems/smallest-string-starting-from-leaf) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 987 | [二叉树的垂序遍历](../../problems/vertical-order-traversal-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 979 | [在二叉树中分配硬币](../../problems/distribute-coins-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 971 | [翻转二叉树以匹配先序遍历](../../problems/flip-binary-tree-to-match-preorder-traversal) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 968 | [监控二叉树](../../problems/binary-tree-cameras) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 965 | [单值二叉树](../../problems/univalued-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 958 | [二叉树的完全性检验](../../problems/check-completeness-of-a-binary-tree) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 951 | [翻转等价二叉树](../../problems/flip-equivalent-binary-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 938 | [二叉搜索树的范围和](../../problems/range-sum-of-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 919 | [完全二叉树插入器](../../problems/complete-binary-tree-inserter) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 897 | [递增顺序搜索树](../../problems/increasing-order-search-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 894 | [所有可能的满二叉树](../../problems/all-possible-full-binary-trees) | [[树](../tree/README.md)] [[递归](../recursion/README.md)] [[记忆化搜索](../memoization/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 889 | [根据前序和后序遍历构造二叉树](../../problems/construct-binary-tree-from-preorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 872 | [叶子相似的树](../../problems/leaf-similar-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 865 | [具有所有最深节点的最小子树](../../problems/smallest-subtree-with-all-the-deepest-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 863 | [二叉树中所有距离为 K 的结点](../../problems/all-nodes-distance-k-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 834 | [树中距离之和](../../problems/sum-of-distances-in-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[图](../graph/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 814 | [二叉树剪枝](../../problems/binary-tree-pruning) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 783 | [二叉搜索树节点最小距离](../../problems/minimum-distance-between-bst-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 776 | [拆分二叉搜索树](../../problems/split-bst) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 742 | [二叉树最近的叶节点](../../problems/closest-leaf-in-a-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 703 | [数据流中的第 K 大元素](../../problems/kth-largest-element-in-a-stream) | [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[数据流](../data-stream/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Easy |
-| 701 | [二叉搜索树中的插入操作](../../problems/insert-into-a-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 700 | [二叉搜索树中的搜索](../../problems/search-in-a-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 687 | [最长同值路径](../../problems/longest-univalue-path) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 671 | [二叉树中第二小的节点](../../problems/second-minimum-node-in-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 669 | [修剪二叉搜索树](../../problems/trim-a-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 666 | [路径总和 IV](../../problems/path-sum-iv) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[数组](../array/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 663 | [均匀树划分](../../problems/equal-tree-partition) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 662 | [二叉树最大宽度](../../problems/maximum-width-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 655 | [输出二叉树](../../problems/print-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 654 | [最大二叉树](../../problems/maximum-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 653 | [两数之和 IV - 输入 BST](../../problems/two-sum-iv-input-is-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 652 | [寻找重复的子树](../../problems/find-duplicate-subtrees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 637 | [二叉树的层平均值](../../problems/average-of-levels-in-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 623 | [在二叉树中增加一行](../../problems/add-one-row-to-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 617 | [合并二叉树](../../problems/merge-two-binary-trees) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 606 | [根据二叉树创建字符串](../../problems/construct-string-from-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 590 | [N 叉树的后序遍历](../../problems/n-ary-tree-postorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Easy |
-| 589 | [N 叉树的前序遍历](../../problems/n-ary-tree-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)]  | Easy |
-| 582 | [杀掉进程](../../problems/kill-process) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 572 | [另一棵树的子树](../../problems/subtree-of-another-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)] [[字符串匹配](../string-matching/README.md)] [[哈希函数](../hash-function/README.md)]  | Easy |
-| 563 | [二叉树的坡度](../../problems/binary-tree-tilt) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 559 | [N 叉树的最大深度](../../problems/maximum-depth-of-n-ary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Easy |
-| 558 | [四叉树交集](../../problems/logical-or-of-two-binary-grids-represented-as-quad-trees) | [[树](../tree/README.md)] [[分治](../divide-and-conquer/README.md)]  | Medium |
-| 549 | [二叉树中最长的连续序列](../../problems/binary-tree-longest-consecutive-sequence-ii) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 545 | [二叉树的边界](../../problems/boundary-of-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 543 | [二叉树的直径](../../problems/diameter-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 538 | [把二叉搜索树转换为累加树](../../problems/convert-bst-to-greater-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 536 | [从字符串生成二叉树](../../problems/construct-binary-tree-from-string) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 530 | [二叉搜索树的最小绝对差](../../problems/minimum-absolute-difference-in-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 515 | [在每个树行中找最大值](../../problems/find-largest-value-in-each-tree-row) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 513 | [找树左下角的值](../../problems/find-bottom-left-tree-value) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 510 | [二叉搜索树中的中序后继 II](../../problems/inorder-successor-in-bst-ii) 🔒 | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 508 | [出现次数最多的子树元素和](../../problems/most-frequent-subtree-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 501 | [二叉搜索树中的众数](../../problems/find-mode-in-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 450 | [删除二叉搜索树中的节点](../../problems/delete-node-in-a-bst) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 449 | [序列化和反序列化二叉搜索树](../../problems/serialize-and-deserialize-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 437 | [路径总和 III](../../problems/path-sum-iii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 431 | [将 N 叉树编码为二叉树](../../problems/encode-n-ary-tree-to-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 429 | [N 叉树的层序遍历](../../problems/n-ary-tree-level-order-traversal) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)]  | Medium |
-| 428 | [序列化和反序列化 N 叉树](../../problems/serialize-and-deserialize-n-ary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 427 | [建立四叉树](../../problems/construct-quad-tree) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 426 | [将二叉搜索树转化为排序的双向链表](../../problems/convert-binary-search-tree-to-sorted-doubly-linked-list) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)] [[双向链表](../doubly-linked-list/README.md)]  | Medium |
-| 404 | [左叶子之和](../../problems/sum-of-left-leaves) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 366 | [寻找二叉树的叶子节点](../../problems/find-leaves-of-binary-tree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 341 | [扁平化嵌套列表迭代器](../../problems/flatten-nested-list-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[队列](../queue/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 337 | [打家劫舍 III](../../problems/house-robber-iii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 333 | [最大 BST 子树](../../problems/largest-bst-subtree) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 331 | [验证二叉树的前序序列化](../../problems/verify-preorder-serialization-of-a-binary-tree) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 314 | [二叉树的垂直遍历](../../problems/binary-tree-vertical-order-traversal) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[哈希表](../hash-table/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 298 | [二叉树最长连续序列](../../problems/binary-tree-longest-consecutive-sequence) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 297 | [二叉树的序列化与反序列化](../../problems/serialize-and-deserialize-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[设计](../design/README.md)] [[字符串](../string/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 285 | [二叉搜索树中的中序后继](../../problems/inorder-successor-in-bst) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 272 | [最接近的二叉搜索树值 II](../../problems/closest-binary-search-tree-value-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 270 | [最接近的二叉搜索树值](../../problems/closest-binary-search-tree-value) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 257 | [二叉树的所有路径](../../problems/binary-tree-paths) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 255 | [验证前序遍历序列二叉搜索树](../../problems/verify-preorder-sequence-in-binary-search-tree) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[递归](../recursion/README.md)] [[二叉树](../binary-tree/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 250 | [统计同值子树](../../problems/count-univalue-subtrees) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 236 | [二叉树的最近公共祖先](../../problems/lowest-common-ancestor-of-a-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 235 | [二叉搜索树的最近公共祖先](../../problems/lowest-common-ancestor-of-a-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 230 | [二叉搜索树中第K小的元素](../../problems/kth-smallest-element-in-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 226 | [翻转二叉树](../../problems/invert-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 222 | [完全二叉树的节点个数](../../problems/count-complete-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 199 | [二叉树的右视图](../../problems/binary-tree-right-side-view) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 173 | [二叉搜索树迭代器](../../problems/binary-search-tree-iterator) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[设计](../design/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 156 | [上下翻转二叉树](../../problems/binary-tree-upside-down) 🔒 | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 145 | [二叉树的后序遍历](../../problems/binary-tree-postorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 144 | [二叉树的前序遍历](../../problems/binary-tree-preorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 129 | [求根节点到叶节点数字之和](../../problems/sum-root-to-leaf-numbers) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 124 | [二叉树中的最大路径和](../../problems/binary-tree-maximum-path-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Hard |
-| 117 | [填充每个节点的下一个右侧节点指针 II](../../problems/populating-next-right-pointers-in-each-node-ii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 116 | [填充每个节点的下一个右侧节点指针](../../problems/populating-next-right-pointers-in-each-node) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 114 | [二叉树展开为链表](../../problems/flatten-binary-tree-to-linked-list) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[链表](../linked-list/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 113 | [路径总和 II](../../problems/path-sum-ii) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 112 | [路径总和](../../problems/path-sum) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 111 | [二叉树的最小深度](../../problems/minimum-depth-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 110 | [平衡二叉树](../../problems/balanced-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 109 | [有序链表转换二叉搜索树](../../problems/convert-sorted-list-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[链表](../linked-list/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 108 | [将有序数组转换为二叉搜索树](../../problems/convert-sorted-array-to-binary-search-tree) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数组](../array/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 107 | [二叉树的层序遍历 II](../../problems/binary-tree-level-order-traversal-ii) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 106 | [从中序与后序遍历序列构造二叉树](../../problems/construct-binary-tree-from-inorder-and-postorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 105 | [从前序与中序遍历序列构造二叉树](../../problems/construct-binary-tree-from-preorder-and-inorder-traversal) | [[树](../tree/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[分治](../divide-and-conquer/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 104 | [二叉树的最大深度](../../problems/maximum-depth-of-binary-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 103 | [二叉树的锯齿形层序遍历](../../problems/binary-tree-zigzag-level-order-traversal) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 102 | [二叉树的层序遍历](../../problems/binary-tree-level-order-traversal) | [[树](../tree/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 101 | [对称二叉树](../../problems/symmetric-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 100 | [相同的树](../../problems/same-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 99 | [恢复二叉搜索树](../../problems/recover-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 98 | [验证二叉搜索树](../../problems/validate-binary-search-tree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 96 | [不同的二叉搜索树](../../problems/unique-binary-search-trees) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[数学](../math/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 95 | [不同的二叉搜索树 II](../../problems/unique-binary-search-trees-ii) | [[树](../tree/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 94 | [二叉树的中序遍历](../../problems/binary-tree-inorder-traversal) | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
diff --git a/tag/trie/README.md b/tag/trie/README.md
deleted file mode 100644
index 1b00eff9c..000000000
--- a/tag/trie/README.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 字典树
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 1948 | [删除系统中的重复文件夹](../../problems/delete-duplicate-folders-in-system) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 1858 | [包含所有前缀的最长单词](../../problems/longest-word-with-all-prefixes) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[字典树](../trie/README.md)]  | Medium |
-| 1804 | [实现 Trie （前缀树） II](../../problems/implement-trie-ii-prefix-tree) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1803 | [统计异或值在范围内的数对有多少](../../problems/count-pairs-with-xor-in-a-range) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1707 | [与数组中元素的最大异或值](../../problems/maximum-xor-with-an-element-from-array) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)]  | Hard |
-| 1698 | [字符串的不同子字符串个数](../../problems/number-of-distinct-substrings-in-a-string) 🔒 | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[后缀数组](../suffix-array/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Medium |
-| 1316 | [不同的循环子字符串](../../problems/distinct-echo-substrings) | [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[滑动窗口](../sliding-window/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1268 | [搜索推荐系统](../../problems/search-suggestions-system) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1233 | [删除子文件夹](../../problems/remove-sub-folders-from-the-filesystem) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1178 | [猜字谜](../../problems/number-of-valid-words-for-each-puzzle) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1166 | [设计文件系统](../../problems/design-file-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1065 | [字符串的索引对](../../problems/index-pairs-of-a-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1032 | [字符流](../../problems/stream-of-characters) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[数据流](../data-stream/README.md)]  | Hard |
-| 1023 | [驼峰式匹配](../../problems/camelcase-matching) | [[字典树](../trie/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 820 | [单词的压缩编码](../../problems/short-encoding-of-words) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 792 | [匹配子序列的单词数](../../problems/number-of-matching-subsequences) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 758 | [字符串中的加粗单词](../../problems/bold-words-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 745 | [前缀和后缀搜索](../../problems/prefix-and-suffix-search) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 720 | [词典中最长的单词](../../problems/longest-word-in-dictionary) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 692 | [前K个高频单词](../../problems/top-k-frequent-words) | [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[桶排序](../bucket-sort/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 677 | [键值映射](../../problems/map-sum-pairs) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 676 | [实现一个魔法字典](../../problems/implement-magic-dictionary) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 648 | [单词替换](../../problems/replace-words) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 642 | [设计搜索自动补全系统](../../problems/design-search-autocomplete-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)] [[数据流](../data-stream/README.md)]  | Hard |
-| 616 | [给字符串添加加粗标签](../../problems/add-bold-tag-in-string) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 588 | [设计内存文件系统](../../problems/design-in-memory-file-system) 🔒 | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 527 | [单词缩写](../../problems/word-abbreviation) 🔒 | [[贪心](../greedy/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 472 | [连接词](../../problems/concatenated-words) | [[深度优先搜索](../depth-first-search/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 440 | [字典序的第K小数字](../../problems/k-th-smallest-in-lexicographical-order) | [[字典树](../trie/README.md)]  | Hard |
-| 425 | [单词方块](../../problems/word-squares) 🔒 | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 421 | [数组中两个数的最大异或值](../../problems/maximum-xor-of-two-numbers-in-an-array) | [[位运算](../bit-manipulation/README.md)] [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |
-| 386 | [字典序排数](../../problems/lexicographical-numbers) | [[深度优先搜索](../depth-first-search/README.md)] [[字典树](../trie/README.md)]  | Medium |
-| 336 | [回文对](../../problems/palindrome-pairs) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 212 | [单词搜索 II](../../problems/word-search-ii) | [[字典树](../trie/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 211 | [添加与搜索单词 - 数据结构设计](../../problems/design-add-and-search-words-data-structure) | [[深度优先搜索](../depth-first-search/README.md)] [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 208 | [实现 Trie (前缀树)](../../problems/implement-trie-prefix-tree) | [[设计](../design/README.md)] [[字典树](../trie/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 140 | [单词拆分 II](../../problems/word-break-ii) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[回溯](../backtracking/README.md)]  | Hard |
-| 139 | [单词拆分](../../problems/word-break) | [[字典树](../trie/README.md)] [[记忆化搜索](../memoization/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
diff --git a/tag/two-pointers/README.md b/tag/two-pointers/README.md
deleted file mode 100644
index bb35f10de..000000000
--- a/tag/two-pointers/README.md
+++ /dev/null
@@ -1,154 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 双指针
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2161 | [根据给定数字划分数组](../../problems/partition-array-according-to-given-pivot) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2149 | [按符号重排数组](../../problems/rearrange-array-elements-by-sign) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2130 | [链表最大孪生和](../../problems/maximum-twin-sum-of-a-linked-list) | [[栈](../stack/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 2108 | [找出数组中的第一个回文字符串](../../problems/find-first-palindromic-string-in-the-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 2105 | [给植物浇水 II](../../problems/watering-plants-ii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 2095 | [删除链表的中间节点](../../problems/delete-the-middle-node-of-a-linked-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 2046 | [给按照绝对值排序的链表排序](../../problems/sort-linked-list-already-sorted-using-absolute-values) 🔒 | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 2035 | [将数组分成两个数组并最小化数组和的差](../../problems/partition-array-into-two-arrays-to-minimize-sum-difference) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)] [[有序集合](../ordered-set/README.md)]  | Hard |
-| 2000 | [反转单词前缀](../../problems/reverse-prefix-of-word) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1963 | [使字符串平衡的最小交换次数](../../problems/minimum-number-of-swaps-to-make-the-string-balanced) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1877 | [数组中最大数对和的最小值](../../problems/minimize-maximum-pair-sum-in-array) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1871 | [跳跃游戏 VII](../../problems/jump-game-vii) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1868 | [两个行程编码数组的积](../../problems/product-of-two-run-length-encoded-arrays) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1861 | [旋转盒子](../../problems/rotating-the-box) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1855 | [下标对中的最大距离](../../problems/maximum-distance-between-a-pair-of-values) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 1850 | [邻位交换的最小次数](../../problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1842 | [下个由相同数字构成的回文串](../../problems/next-palindrome-using-same-digits) 🔒 | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1826 | [有缺陷的传感器](../../problems/faulty-sensor) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 1813 | [句子相似性 III](../../problems/sentence-similarity-iii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1793 | [好子数组的最大分数](../../problems/maximum-score-of-a-good-subarray) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 1782 | [统计点对的数目](../../problems/count-pairs-of-nodes) | [[图](../graph/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Hard |
-| 1768 | [交替合并字符串](../../problems/merge-strings-alternately) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1755 | [最接近目标值的子序列和](../../problems/closest-subsequence-sum) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[状态压缩](../bitmask/README.md)]  | Hard |
-| 1754 | [构造字典序最大的合并字符串](../../problems/largest-merge-of-two-strings) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1750 | [删除字符串两端相同字符后的最短长度](../../problems/minimum-length-of-string-after-deleting-similar-ends) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1721 | [交换链表中的节点](../../problems/swapping-nodes-in-a-linked-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1712 | [将数组分成三个子数组的方案数](../../problems/ways-to-split-array-into-three-subarrays) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[前缀和](../prefix-sum/README.md)]  | Medium |
-| 1679 | [K 和数对的最大数目](../../problems/max-number-of-k-sum-pairs) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1634 | [求两个多项式链表的和](../../problems/add-two-polynomials-represented-as-linked-lists) 🔒 | [[链表](../linked-list/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1616 | [分割两个字符串得到回文串](../../problems/split-two-strings-to-make-palindrome) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1577 | [数的平方等于两数乘积的方法数](../../problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1574 | [删除最短的子数组使剩余数组有序](../../problems/shortest-subarray-to-be-removed-to-make-array-sorted) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 1570 | [两个稀疏向量的点积](../../problems/dot-product-of-two-sparse-vectors) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1537 | [最大得分](../../problems/get-the-maximum-score) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1508 | [子数组和排序后的区间和](../../problems/range-sum-of-sorted-subarray-sums) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1498 | [满足条件的子序列数目](../../problems/number-of-subsequences-that-satisfy-the-given-sum-condition) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1471 | [数组中的 k 个最强值](../../problems/the-k-strongest-values-in-an-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1385 | [两个数组间的距离值](../../problems/find-the-distance-value-between-two-arrays) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1346 | [检查整数及其两倍数是否存在](../../problems/check-if-n-and-its-double-exist) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1332 | [删除回文子序列](../../problems/remove-palindromic-subsequences) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 1265 | [逆序打印不可变链表](../../problems/print-immutable-linked-list-in-reverse) 🔒 | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 1237 | [找出给定方程的正整数解](../../problems/find-positive-integer-solution-for-a-given-equation) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 1229 | [安排会议日程](../../problems/meeting-scheduler) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1214 | [查找两棵二叉搜索树之和](../../problems/two-sum-bsts) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1163 | [按字典序排在最后的子串](../../problems/last-substring-in-lexicographical-order) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 1147 | [段式回文](../../problems/longest-chunked-palindrome-decomposition) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)] [[哈希函数](../hash-function/README.md)] [[滚动哈希](../rolling-hash/README.md)]  | Hard |
-| 1099 | [小于 K 的两数之和](../../problems/two-sum-less-than-k) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 1093 | [大样本统计](../../problems/statistics-from-a-large-sample) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[概率与统计](../probability-and-statistics/README.md)]  | Medium |
-| 1089 | [复写零](../../problems/duplicate-zeros) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 1048 | [最长字符串链](../../problems/longest-string-chain) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 1040 | [移动石子直到连续 II](../../problems/moving-stones-until-consecutive-ii) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 1023 | [驼峰式匹配](../../problems/camelcase-matching) | [[字典树](../trie/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Medium |
-| 986 | [区间列表的交集](../../problems/interval-list-intersections) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 977 | [有序数组的平方](../../problems/squares-of-a-sorted-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 969 | [煎饼排序](../../problems/pancake-sorting) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 948 | [令牌放置](../../problems/bag-of-tokens) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 942 | [增减字符串匹配](../../problems/di-string-match) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 925 | [长按键入](../../problems/long-pressed-name) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 923 | [三数之和的多种可能](../../problems/3sum-with-multiplicity) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[计数](../counting/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 922 | [按奇偶排序数组 II](../../problems/sort-array-by-parity-ii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 917 | [仅仅反转字母](../../problems/reverse-only-letters) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 905 | [按奇偶排序数组](../../problems/sort-array-by-parity) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 881 | [救生艇](../../problems/boats-to-save-people) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 876 | [链表的中间结点](../../problems/middle-of-the-linked-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 845 | [数组中的最长山脉](../../problems/longest-mountain-in-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[枚举](../enumeration/README.md)]  | Medium |
-| 844 | [比较含退格的字符串](../../problems/backspace-string-compare) | [[栈](../stack/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 838 | [推多米诺](../../problems/push-dominoes) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Medium |
-| 832 | [翻转图像](../../problems/flipping-an-image) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Easy |
-| 826 | [安排工作以达到最大收益](../../problems/most-profit-assigning-work) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 825 | [适龄的朋友](../../problems/friends-of-appropriate-ages) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 821 | [字符的最短距离](../../problems/shortest-distance-to-a-character) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 809 | [情感丰富的文字](../../problems/expressive-words) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 795 | [区间子数组个数](../../problems/number-of-subarrays-with-bounded-maximum) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 777 | [在LR字符串中交换相邻字符](../../problems/swap-adjacent-in-lr-string) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 763 | [划分字母区间](../../problems/partition-labels) | [[贪心](../greedy/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 723 | [粉碎糖果](../../problems/candy-crush) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[矩阵](../matrix/README.md)] [[模拟](../simulation/README.md)]  | Medium |
-| 719 | [找出第 k 小的距离对](../../problems/find-k-th-smallest-pair-distance) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 696 | [计数二进制子串](../../problems/count-binary-substrings) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 680 | [验证回文字符串 Ⅱ](../../problems/valid-palindrome-ii) | [[贪心](../greedy/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 658 | [找到 K 个最接近的元素](../../problems/find-k-closest-elements) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 653 | [两数之和 IV - 输入 BST](../../problems/two-sum-iv-input-is-a-bst) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)]  | Easy |
-| 633 | [平方数之和](../../problems/sum-of-square-numbers) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 611 | [有效三角形的个数](../../problems/valid-triangle-number) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 581 | [最短无序连续子数组](../../problems/shortest-unsorted-continuous-subarray) | [[栈](../stack/README.md)] [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Medium |
-| 567 | [字符串的排列](../../problems/permutation-in-string) | [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[滑动窗口](../sliding-window/README.md)]  | Medium |
-| 557 | [反转字符串中的单词 III](../../problems/reverse-words-in-a-string-iii) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 556 | [下一个更大元素 III](../../problems/next-greater-element-iii) | [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 541 | [反转字符串 II](../../problems/reverse-string-ii) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 532 | [数组中的 k-diff 数对](../../problems/k-diff-pairs-in-an-array) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 524 | [通过删除字母匹配到字典里最长单词](../../problems/longest-word-in-dictionary-through-deleting) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 522 | [最长特殊序列 II](../../problems/longest-uncommon-subsequence-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 481 | [神奇字符串](../../problems/magical-string) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 475 | [供暖器](../../problems/heaters) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 457 | [环形数组是否存在循环](../../problems/circular-array-loop) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 443 | [压缩字符串](../../problems/string-compression) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 408 | [有效单词缩写](../../problems/valid-word-abbreviation) 🔒 | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 392 | [判断子序列](../../problems/is-subsequence) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Easy |
-| 360 | [有序转化数组](../../problems/sort-transformed-array) 🔒 | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 350 | [两个数组的交集 II](../../problems/intersection-of-two-arrays-ii) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 349 | [两个数组的交集](../../problems/intersection-of-two-arrays) | [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 345 | [反转字符串中的元音字母](../../problems/reverse-vowels-of-a-string) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 344 | [反转字符串](../../problems/reverse-string) | [[递归](../recursion/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 295 | [数据流的中位数](../../problems/find-median-from-data-stream) | [[设计](../design/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 287 | [寻找重复数](../../problems/find-the-duplicate-number) | [[位运算](../bit-manipulation/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 283 | [移动零](../../problems/move-zeroes) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 277 | [搜寻名人](../../problems/find-the-celebrity) 🔒 | [[贪心](../greedy/README.md)] [[图](../graph/README.md)] [[双指针](../two-pointers/README.md)] [[交互](../interactive/README.md)]  | Medium |
-| 272 | [最接近的二叉搜索树值 II](../../problems/closest-binary-search-tree-value-ii) 🔒 | [[栈](../stack/README.md)] [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[双指针](../two-pointers/README.md)] [[二叉树](../binary-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 259 | [较小的三数之和](../../problems/3sum-smaller) 🔒 | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 253 | [会议室 II](../../problems/meeting-rooms-ii) 🔒 | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 251 | [展开二维向量](../../problems/flatten-2d-vector) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[迭代器](../iterator/README.md)]  | Medium |
-| 246 | [中心对称数](../../problems/strobogrammatic-number) 🔒 | [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 244 | [最短单词距离 II](../../problems/shortest-word-distance-ii) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 234 | [回文链表](../../problems/palindrome-linked-list) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 202 | [快乐数](../../problems/happy-number) | [[哈希表](../hash-table/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 189 | [轮转数组](../../problems/rotate-array) | [[数组](../array/README.md)] [[数学](../math/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 186 | [翻转字符串里的单词 II](../../problems/reverse-words-in-a-string-ii) 🔒 | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 170 | [两数之和 III - 数据结构设计](../../problems/two-sum-iii-data-structure-design) 🔒 | [[设计](../design/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[双指针](../two-pointers/README.md)] [[数据流](../data-stream/README.md)]  | Easy |
-| 167 | [两数之和 II - 输入有序数组](../../problems/two-sum-ii-input-array-is-sorted) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[二分查找](../binary-search/README.md)]  | Medium |
-| 165 | [比较版本号](../../problems/compare-version-numbers) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 161 | [相隔为 1 的编辑距离](../../problems/one-edit-distance) 🔒 | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 160 | [相交链表](../../problems/intersection-of-two-linked-lists) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 151 | [翻转字符串里的单词](../../problems/reverse-words-in-a-string) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 148 | [排序链表](../../problems/sort-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)] [[分治](../divide-and-conquer/README.md)] [[排序](../sorting/README.md)] [[归并排序](../merge-sort/README.md)]  | Medium |
-| 143 | [重排链表](../../problems/reorder-list) | [[栈](../stack/README.md)] [[递归](../recursion/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 142 | [环形链表 II](../../problems/linked-list-cycle-ii) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 141 | [环形链表](../../problems/linked-list-cycle) | [[哈希表](../hash-table/README.md)] [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 125 | [验证回文串](../../problems/valid-palindrome) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)]  | Easy |
-| 88 | [合并两个有序数组](../../problems/merge-sorted-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Easy |
-| 86 | [分隔链表](../../problems/partition-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 82 | [删除排序链表中的重复元素 II](../../problems/remove-duplicates-from-sorted-list-ii) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 80 | [删除有序数组中的重复项 II](../../problems/remove-duplicates-from-sorted-array-ii) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 75 | [颜色分类](../../problems/sort-colors) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 61 | [旋转链表](../../problems/rotate-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 42 | [接雨水](../../problems/trapping-rain-water) | [[栈](../stack/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[动态规划](../dynamic-programming/README.md)] [[单调栈](../monotonic-stack/README.md)]  | Hard |
-| 31 | [下一个排列](../../problems/next-permutation) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 28 | [实现 strStr()](../../problems/implement-strstr) | [[双指针](../two-pointers/README.md)] [[字符串](../string/README.md)] [[字符串匹配](../string-matching/README.md)]  | Easy |
-| 27 | [移除元素](../../problems/remove-element) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 26 | [删除有序数组中的重复项](../../problems/remove-duplicates-from-sorted-array) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Easy |
-| 19 | [删除链表的倒数第 N 个结点](../../problems/remove-nth-node-from-end-of-list) | [[链表](../linked-list/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
-| 18 | [四数之和](../../problems/4sum) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 16 | [最接近的三数之和](../../problems/3sum-closest) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 15 | [三数之和](../../problems/3sum) | [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)] [[排序](../sorting/README.md)]  | Medium |
-| 11 | [盛最多水的容器](../../problems/container-with-most-water) | [[贪心](../greedy/README.md)] [[数组](../array/README.md)] [[双指针](../two-pointers/README.md)]  | Medium |
diff --git a/tag/union-find/README.md b/tag/union-find/README.md
deleted file mode 100644
index 7ac700ad6..000000000
--- a/tag/union-find/README.md
+++ /dev/null
@@ -1,70 +0,0 @@
-<!--|This file generated by command(leetcode tag); DO NOT EDIT.            |-->
-<!--+----------------------------------------------------------------------+-->
-<!--|@author    awesee <openset.wang@gmail.com>                           |-->
-<!--|@link      https://github.com/awesee                                 |-->
-<!--|@home      https://github.com/awesee/leetcode                        |-->
-<!--+----------------------------------------------------------------------+-->
-
-## [话题分类](../README.md) > 并查集
-
-| # | 题目 | 标签 | 难度 |
-| :-: | - | - | :-: |
-| 2157 | [字符串分组](../../problems/groups-of-strings) | [[位运算](../bit-manipulation/README.md)] [[并查集](../union-find/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 2092 | [找出知晓秘密的所有专家](../../problems/find-all-people-with-secret) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 2076 | [处理含限制条件的好友请求](../../problems/process-restricted-friend-requests) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 2003 | [每棵子树内缺失的最小基因值](../../problems/smallest-missing-genetic-value-in-each-subtree) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[动态规划](../dynamic-programming/README.md)]  | Hard |
-| 1998 | [数组的最大公因数排序](../../problems/gcd-sort-of-an-array) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1970 | [你能穿过矩阵的最后一天](../../problems/last-day-where-you-can-still-cross) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1905 | [统计子岛屿](../../problems/count-sub-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1724 | [检查边长度限制的路径是否存在 II](../../problems/checking-existence-of-edge-length-limited-paths-ii) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)]  | Hard |
-| 1722 | [执行交换操作后的最小汉明距离](../../problems/minimize-hamming-distance-after-swap-operations) | [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1697 | [检查边长度限制的路径是否存在](../../problems/checking-existence-of-edge-length-limited-paths) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[排序](../sorting/README.md)]  | Hard |
-| 1632 | [矩阵转换后的秩](../../problems/rank-transform-of-a-matrix) | [[贪心](../greedy/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[拓扑排序](../topological-sort/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 1631 | [最小体力消耗路径](../../problems/path-with-minimum-effort) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1627 | [带阈值的图连通性](../../problems/graph-connectivity-with-threshold) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 1584 | [连接所有点的最小费用](../../problems/min-cost-to-connect-all-points) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)]  | Medium |
-| 1579 | [保证图可完全遍历](../../problems/remove-max-number-of-edges-to-keep-graph-fully-traversable) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 1569 | [将子数组重新排序得到同一个二叉查找树的方案数](../../problems/number-of-ways-to-reorder-array-to-get-same-bst) | [[树](../tree/README.md)] [[并查集](../union-find/README.md)] [[二叉搜索树](../binary-search-tree/README.md)] [[记忆化搜索](../memoization/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)] [[分治](../divide-and-conquer/README.md)] [[动态规划](../dynamic-programming/README.md)] [[二叉树](../binary-tree/README.md)] [[组合数学](../combinatorics/README.md)]  | Hard |
-| 1559 | [二维网格图中探测环](../../problems/detect-cycles-in-2d-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1489 | [找到最小生成树里的关键边和伪关键边](../../problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)] [[排序](../sorting/README.md)] [[强连通分量](../strongly-connected-component/README.md)]  | Hard |
-| 1391 | [检查网格中是否存在有效路径](../../problems/check-if-there-is-a-valid-path-in-a-grid) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1361 | [验证二叉树](../../problems/validate-binary-tree-nodes) | [[树](../tree/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[二叉树](../binary-tree/README.md)]  | Medium |
-| 1319 | [连通网络的操作次数](../../problems/number-of-operations-to-make-network-connected) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 1267 | [统计参与通信的服务器](../../problems/count-servers-that-communicate) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[计数](../counting/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1258 | [近义词句子](../../problems/synonymous-sentences) 🔒 | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)] [[回溯](../backtracking/README.md)]  | Medium |
-| 1254 | [统计封闭岛屿的数目](../../problems/number-of-closed-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 1202 | [交换字符串中的元素](../../problems/smallest-string-with-swaps) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1168 | [水资源分配优化](../../problems/optimize-water-distribution-in-a-village) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)]  | Hard |
-| 1135 | [最低成本联通所有城市](../../problems/connecting-cities-with-minimum-cost) 🔒 | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[最小生成树](../minimum-spanning-tree/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1102 | [得分最高的路径](../../problems/path-with-maximum-minimum-value) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Medium |
-| 1101 | [彼此熟识的最早时间](../../problems/the-earliest-moment-when-everyone-become-friends) 🔒 | [[并查集](../union-find/README.md)] [[数组](../array/README.md)]  | Medium |
-| 1061 | [按字典序排列最小的等效字符串](../../problems/lexicographically-smallest-equivalent-string) 🔒 | [[并查集](../union-find/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 1020 | [飞地的数量](../../problems/number-of-enclaves) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 990 | [等式方程的可满足性](../../problems/satisfiability-of-equality-equations) | [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 959 | [由斜杠划分区域](../../problems/regions-cut-by-slashes) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 952 | [按公因数计算最大组件大小](../../problems/largest-component-size-by-common-factor) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[数学](../math/README.md)]  | Hard |
-| 947 | [移除最多的同行或同列石头](../../problems/most-stones-removed-with-same-row-or-column) | [[深度优先搜索](../depth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 928 | [尽量减少恶意软件的传播 II](../../problems/minimize-malware-spread-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 924 | [尽量减少恶意软件的传播](../../problems/minimize-malware-spread) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 886 | [可能的二分法](../../problems/possible-bipartition) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 839 | [相似字符串组](../../problems/similar-string-groups) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[字符串](../string/README.md)]  | Hard |
-| 827 | [最大人工岛](../../problems/making-a-large-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 803 | [打砖块](../../problems/bricks-falling-when-hit) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Hard |
-| 785 | [判断二分图](../../problems/is-graph-bipartite) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 778 | [水位上升的泳池中游泳](../../problems/swim-in-rising-water) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[二分查找](../binary-search/README.md)] [[矩阵](../matrix/README.md)] [[堆（优先队列）](../heap-priority-queue/README.md)]  | Hard |
-| 765 | [情侣牵手](../../problems/couples-holding-hands) | [[贪心](../greedy/README.md)] [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 737 | [句子相似性 II](../../problems/sentence-similarity-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 721 | [账户合并](../../problems/accounts-merge) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[字符串](../string/README.md)]  | Medium |
-| 711 | [不同岛屿的数量 II](../../problems/number-of-distinct-islands-ii) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Hard |
-| 695 | [岛屿的最大面积](../../problems/max-area-of-island) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 694 | [不同岛屿的数量](../../problems/number-of-distinct-islands) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[哈希表](../hash-table/README.md)] [[哈希函数](../hash-function/README.md)]  | Medium |
-| 685 | [冗余连接 II](../../problems/redundant-connection-ii) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Hard |
-| 684 | [冗余连接](../../problems/redundant-connection) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 547 | [省份数量](../../problems/number-of-provinces) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 399 | [除法求值](../../problems/evaluate-division) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)] [[数组](../array/README.md)] [[最短路](../shortest-path/README.md)]  | Medium |
-| 323 | [无向图中连通分量的数目](../../problems/number-of-connected-components-in-an-undirected-graph) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 305 | [岛屿数量 II](../../problems/number-of-islands-ii) 🔒 | [[并查集](../union-find/README.md)] [[数组](../array/README.md)]  | Hard |
-| 261 | [以图判树](../../problems/graph-valid-tree) 🔒 | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[图](../graph/README.md)]  | Medium |
-| 200 | [岛屿数量](../../problems/number-of-islands) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 130 | [被围绕的区域](../../problems/surrounded-regions) | [[深度优先搜索](../depth-first-search/README.md)] [[广度优先搜索](../breadth-first-search/README.md)] [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[矩阵](../matrix/README.md)]  | Medium |
-| 128 | [最长连续序列](../../problems/longest-consecutive-sequence) | [[并查集](../union-find/README.md)] [[数组](../array/README.md)] [[哈希表](../hash-table/README.md)]  | Medium |